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ELEMENTS OF PHYSIOLOGY.
&
LONDON: PRINTED BY SAMUEL BENTLEY, Dorset-Street, Fleet-Street.
ELEMENTS OF PHYSIOLOGY.
BY J. MULLER, M.D.
PROFESSOR OF ANATOMY AND PHYSIOLOGY IN THE UNIVERSITY OF BERLIN, ETC.
TRANSLATED FROM THE GERMAN, WITH NOTES.
BY WILLIAM BALY, M.D.
GRADUATE OF THE UNIVERSITY OF BERLIN, AND PHYSICIAN TO THE ST. PANCRAS INFIRMARY.
ILLUSTRATED WITH STEEL PLATES, AND NUMEROUS WOOD ENGRAVINGS.
VOL. I.
CONTAINING GENERAL PHYSIOLOGY, THE BLOOD AND CIRCULATING SYSTEM, THE LYMPH AND LYMPHATIC SYSTEM, RESPIRATION, NUTRITION, GROWTH AND REPRODUCTION, SECRETION, DIGESTION, FUNCTIONS OF THE GLANDS WITHOUT EFFERENT DUCTS, EXCRETION,
i AND THE NERVOUS SYSTEM.
LONDON: | PRINTED FOR TAYLOR AND WALTON,
BOOKSELLERS AND PUBLISHERS TO UNIVERSITY COLLEGE, 28, UPPER GOWER STREET.
1838.
CRT SOE Library, sit from
LONDON: PRINTED BY SAMUEL BENTLEY, Dorset Street, Fleet Street.
TRANSLATOR’S PREFACE.
Tue Translator feels that no other apology is necessary for introducing the present work to the British student of medicine than is afforded by the reputation of its Author as a physiologist, and the high character which the work has acquired, not only in Germany, but throughout Europe. Its translation was suggested to him by Dr. George Burrows, to whom he has on several occa- sions been indebted for advice always given with the greatest readiness.
To render a faithful version of the original has been the Trans- lator’s chief care; but at the same time he has found, that, to make it fitted to the wants of the student, something more was re- quired. In some instances the order in which the facts, and in- ductions from them, are stated, has been altered, that their con- nection might be easier of comprehension. In other cases it has been deemed advisable to omit from the text, and to place in the form of notes, discussions on subjects which, though interesting in themselves, did not appear to come within the limits of what is necessary or desirable in a text-book on Human physiology, parti- cularly when they formed a digression which tended to interfere with the course of the student’s reading ; some few paragraphs have been entirely omitted, chiefly with the view of avoiding un- necessary repetition. To facilitate the labours of the student, like- wise, the paragraph where a new topic commences has been headed with a short statement of this in italics. Steel plates and wood- cuts, which, the Translator hopes, will be found useful, have also
been added.*
The additions made by the Translator consist almost entirely
of newly-discovered facts, and are consequently, on account of the
* The subjects for the woodcuts were drawn on the wood by Mr. W. Bagg, and engraved under his direction.
vi TRANSLATOR'S PREFACE.
completeness of the original work at the time of its publication in
1835, few in number; they are distinguished by being included in brackets.
In reducing the numbers from the French to the English?stand-
ard of measurement, an English inch has been regarded as 43 of a French inch; an English cubic inch as +}{ of a French cubic inch.
The Translator cannot too strongly express his grateful acknow- ledgements for the very kind and valuable assistance that he has received from Dr. Sharpey, Dr. R. Willis, and Mr. Quain : their advice has mainly guided him in the execution of his task, and he has derived confidence from the consciousness of having such friends willing to aid him.
He avails himself, also, with much pleasure, of this opportunity of acknowledging the many marks of kindness and friendship which he has experienced at the hands of Dr. P. M. Latham, and for which he must always retain a sense of gratitude.
56, Devonshire Street.
CONTENTS.
PROLEGOMENA ON GENERAL PHYSIOLOGY.
Definition of Physiology - Organic matter ; its elementary composition i characters that distinguish it from inorganic matter its decomposition .. 38 k state in which the mineral Epa exist in it
its simplest forms 50 . ..
its source, —its production by plants
m equivocal generation 5
- Of organism and life a bo Organised bodies,—their depngiging eens The organic force ee i sa Vital stimuli T zi ove Ee — their mode of action .. oe ————— distinguished from other stimuli of not all equally necessary to the infant and adult Death .. AG ae sees a s its cause .. = +. Decay and renovation of the organic mater a ae cause Sources of the new matter, and renovation of the organic force ..
. Of the organism and life of animals Animals as distinguished from plants Functions of animals ; their classification Organic attraction Animal excitability,—its — Exhaustion attended with material change Effect of exercise Reaction,—its laws Stimuli,—their mode of action Medicinal agents,—their classification, and shite of action Brunonian theory > as a Theory of the contra- S e
- The properties common to organic and inorganic bodies
. Electricity ; its sources generally, , electric fishes
~ electric phenomena in frogs sa electricity in the human body ..
2. Developement of heat ie ae in warm-blooded animals at different ages os
viii CONTENTS.
Effects of external cold on warm-blooded animals,—hybernation of external heat .. a
Developement of caloric in cold- flodi vertebrata
in invertebrate animals
Source of animal heat me in respiration .. in organic processes in nervous influence Cause of hybernation es os
3. Developement of light in animals Phosphorescence of the sea a . Luminous insects t a or Developement of light in ‘hu higher animals ., Note on the temperature of insects .. Seay
SPECIAL PHYSIOLOGY.
ree ee
BOOK I.
Of the circulating fluids, their motion, and the vascular system.
SECTION I.
Of the blood.
Its general properties CHAPTER 1.— Microscopic and mechanical examination of the blood Of the red particles
their form
their size Chyle globules in the blood Action of water on the red particles Nuclei of the red particles Effect of different substances on the oh par ticles Historical account of the red particles Of the liquor sanguinis 1. Of the fibrin Ss p °. Its state in the blood Its proportion to the other oela in arterial and venous blood Coagulation of the blood in inflammation Cause of the buffy coat
2. Of the serum ne z Ae a its composition es Ee ———__—— in different sexes, ages, and temperaments
CONTENTS.
CHAPTER 11.—Chemical analysis of the blood 1. Of the red particles Ag : The nuclei,—the red colouring matter State in which the iron exists in the blood 2. Of the fibrin = oe 3. Of the serum Ss 5 4. The fatty matter of the blood CHAPTER 111.—Analysis of the blood by galvanism Dutrochet’s hypothesis refuted iia
No electric currents in the blood Bellingeri’s experiments
oe
CHAPTER 1v.—Of the organic properties and relations of the blood
a. The vivifying influence of the blood Ns Necessity for arterial blood was Transfusion
b. Evidences of life in the blood itself .. Automatic movements of the red particles Motions in coagulating blood Bs a The organic fluids as well as the solids have life
c. Formation of the blood Eo In the adult In the embryo .. .
Influence of respiration on the PE A of ne blood excretion
SECTION II. Of the circulation of the blood and the vascular system.
CHAPTER 1.—Of the forms of the vascular system in the animal king- dom a Sc oe
Circular currents in fie lower animals
Vascular system in the avertebrate classes
—in fishes ., BE i
in reptiles = ar
Metamorphosis of the circulating organs in the stinkin
Aortic arches in the embryo of the higher vertebrata st
Various forms of the circulating system compared with reference to the greater and lesser circulation a
Portal circulation a8
Essential characters of the Niat =
CHAPTER 11.—Of the general phenomena of the circulation . The heart’s action,—its frequency Order of its contractions .. Cause of the impulse 5 Sounds of the heart, —their cause
oe ee
a. The lesser or pulmonary circulation .. a ae Course of the blood through the right cavities of the heart Capillary network of the lungs u en
X CONTENTS.
b. Greater or systemic circulation we ia wile Course of the blood through the left cavities of the heart Circumstances that influence the motion of the blood in the arteries Anastomoses >—retia mirabilia Collateral circulation Capillary system of the T a
c. Portal circulation T i Communications between de venous systems of the poi and cava = Rate of the blood’s motion .. += ex -s ey a es
CHAPTER 111.—Of the heart considered as the cause of the circulation of
the blood .. na 3% Pa se oe Cause of its action eo a es = aa A
1. Influence of the respiration on the heart’s action
2. Influence of the nerves on the hearts action Nerves of the heart,—experiments of Humboldt, Budai and vien Influence of the brain and spinal cord on the heart Circulation in acephalous monsters .. oe aa Influence of the sympathetic nerve on the action of the heart ..
CHAPTER IV.—Of the individual parts of the vascular system
Of the arteries .. s
Their elasticity, —the pulse
Arteries not muscular 6s
Vital contractility of arteries
Force and rate of the blood’s motion in the arteries
Influence of respiration and of anastomoses on the motion of the fant in the arteries .. On
Of the capillaries
, Structure of the capillaries Capillaries defined rè their size . Form of the capillary network ae Vascularity of different parts Have the minute vessels open mouths ?— serous Se Parts in which the existence of blood-vessels is doubtful Have the capillaries membranous parietes? .. . Circulation in the capillaries T so As viewed by the microscope . T a a Degree of resistance offered to, and rate of the blood’s motion in the ane. laries ‘ oe <s ia ae re
The heart’s action ‘ie ioe moving power ar AF ss The red particles themselves are passive, and are not arrested in the in
laries zë K$ . ac a Vital turgescence ws ae vs ES Erection - . a Contractility of Je a y Effects of the application of different S T to them Inflammation .. bc Sc Influence of the nerves on a capita circulation Of the veins
CONTENTS.
Auxiliaries of the venous circulation,—the valves,—the heart Influence of respiration on the venous circulation State of the vessels after death ar 5 ee oe ee CHAPTER v.—Of the action of the blood- aici in the processes of ab- sorption and exudation
. Of absorption .. oe aie oe oe Proofs of absorption independent of the lymphatics sell logical ae Experiments of Magendie, Emmert, Tiedemann, and others Imbibition T Endosmose
oo oo oe
eo ee eo ee
ee oe oe eo oe oe
Time required for absorption by imbibition into the capillaries Mode of action of poisons .. ee Bie 2 Passage of ingesta into the secretions Matters absorbed must be in solution 3 The laws of endosmosis modified in the animal body Absorption by organic attraction - .. as Absorption aided by the action of the heart .. Influence of galvanism, of the nerves, and of ana on 1 imbibition Changes produced by the vessels on the matters absorbed Cutaneous absorption ae Interstitial absorption oe
oe ee
Of exhalation and exudation 3h
Exudation and exhalation from physical causes The process during life modified by organic law Exudation of secretions .. ae
SECTION III.
Of the lymph and the lymphatic vessels.
CHAPTER 1.—Of the lymph Physical and chemical properties of lymph Human lymph,—its microscopic characters Lymph of the frog : Globules of the lymph and whet
CHAPTER 11.—Of the mode of origin and structure of the lymphatic vessels sa
Reticulated and cellular o S Have the lacteals open mouths ? Structure of the intestinal villi intestinal mucous membrane The absorbent glands $ ws oe Structure of the absorbent vessels .. ies mt Communication of the absorbents with the secreting canals of assis Communication of the absorbents with small veins Terminations of the absorbents Lymphatic hearts ve
ee ee
ee ee oe
CHAPTER 111.—Of the functions of the absorbents Source of the lymph i A
1. Of the absorption by the lymphatics and lacteals
xii CONTENTS.
Proofs tbat these vessels absorb a a Peculiarities of the lymphatic and lacteal absorption Power by which they absorb Ar
2. Change effected by the lymphatic and lacteal vessels on their contents
. Motion of the lymph and chyle T E = E The moving power oe T are Rate of motion of the ‘ying and chyle Si os
BOOK II.
Of the chemical changes produced in the organic fluids and organised textures under the influence of the vital laws.
Purely chemical processes .. . = . p ` 287 Organic chemical processes—assimilation ne 5 3 289
SECTION I. Of respiration.
CHAPTER 1.—Of respiration in general .. The atmosphere, —respirable and ner Aep gases Aquatic respiration ae
The respiratory movements, —yvolume of air respired .. Necessity of respiration to different animals ..
CHAPTER 11.—Of the respiratory apparatus
Different forms of the respiratory apparatus ..
In avertebrate animals F P<
In vertebrate animals CHAPTER 111,—Of the respiration of man and animals
. Of respiration in the air
Changes produced in the air Be miy of car TE a ponerse
Amount of oxygen consumed ce T : se
Changes produced in the proportion of the aris in the air = respira- INOS ase on oe oe . ae
Respiration of JE Ban SmE á ; ai Comparison of the products of the EA of sal and warm-blooded
animals or = ee
. Of respiration in the water ee ee
Changes produced in the water by the respiration of thes
Respiration of fishes by the skin,—in the air 3. Of the respiration of the embryo of animals
Respiration of the embryos of birds and insects of mammalia Blood of the foetus a << \. The liquor amnios oe va s .
CHAPTER 1v.—Of the changes which the blood undergoes in the lungs Differences between arterial and venous blood. . oe . .
ee ~~ nn
CONTENTS.
a. Experiments on arterial blood b. Experiments on venous blood
CHAPTER v.—Of the chemical process of respiration Conditions on which the process depends The different theories to explain the process .. Products of respiration in hydrogen and nitrogen = Source of the carbonic acid evolved during respiration ..
oe
CHAPTER v1.—Of the respiratory movements and the respiratory nerves a. The movements of respiration Movements of the thorax .. of the larynx and fauces Contractility of the lungs and bronchi
eo ee
b. Of the influence of the nerves on the function of respiration Source of the nervous influence for the respiratory movements Sir C. Bell’s views a ‘es Ae a Sympathetic affections of the respiratory muscles,—coughing, vomiting, &c. Cause of the respiratory movements ,.
Cause of the first respiration ae Effects of division of the vagus nerves
oe ee
eo oe
ee oe
SECTION II.
Of nutrition, growth, and reproduction.
CHAPTER 1.—Of nutrition
a. Of the nutritive process
Nature of the process; relation of the red particles of the blood to the process Source of the new material for the tissues
Modification of nutrition by certain agents
Nutrition dependent on the original creative power
Renewal of material in the fluids of the body ..
in the solids of the body..
ù. Chemical composition of the organised tissues .. 1. The brain, spinal marrow, and nerves
2. Muscle
3. The bones
4, Cartilage k
5. The glands es T
6. The different membranes ..
eo ee ee
c. Influence of the nerves on nutrition
CHAPTER 11.—Of growth
eo
a. Of the growth of organised parts by interstitial deposition Bone,—its structure ome ae — its mode of growth .. Growth of muscles and nerves
b. Of the growth of unorganised non-vascular parts by the successive deposition
of new layers me ve se ‘ os 1. Growth and structure of the horny tissues bs a, Epidermis and epithelium .. oe
CONTENTS.
. Nails, claws, and hoofs
so) Hans.. es ee
-Horis .. s :
. Growth and structure of the teeth
of the crystalline lens
. Of the laws of growth and changes of form Limits to growth and change of form Law of developement from a uniform type
CHAPTER 111.—Of reproduction .. Laws of reproduction 1 Reproduction of polypes .. a Production of double monsters Reproduction of planariæ and annelides
— in mollusca and articulata in amphibia .. P Influence of the nerves on reproduction Reproduction of the tissues 6
. Reproduction unaccompanied by inflammation of organised tissues of unorganised tissues ,, — The horny structures The teeth
—— The crystalline lens ..
. Reproduction attended with inflammation —_——-——. with adhesive inflammation Formation of new vessels in fibrin .. Reunion of divided parts .. ve
of cartilage and fibrous tissues of bone,—callus .. ou of serous membranes,—skin .. of mucous membranes, —glands of nerves,—experiments thereon of brain and spinal cord Ot
. Reproduction with suppurative inflammation The process of granulation .. - go Reproduction of the skin by granulation
— of bones after necrosis ..
CONTENTS.
SECTION III.
Of secretion.
CHAPTER 1.—Of the secretions in general. Distinction of secretions and excretions a The secretions divided into two kinds ee Secreting apparatus.—Secreting cells ` ss The cellular and adipose tissue = oe The fat—Secreting membranes—Serous membranes The mucous membranes .. oe $s Mucus... So “
The skin,—its n iR Glands = ee ve
CHAPTER 11,—Of the internal structure of the glands. Former opinions regarding their structure Their simplest form a cecal tube or a follicle Compound glands formed of ramified cecal canals The lachrymal gland Se x The mammary—the salivary glands The pancreas... 7 . .. The liver A T Glands formed of tubular, a rami ified canals The kidneys ir . . The testes General results relative to the str = of Ri Measurements of secreting canals, &¢. a
CHAPTER 111.— Of the process of secretion.
1. Of the causes of secretion s ta £i General conditions:of a secreting organ iS zè = Seat of the secreting process,—mode in which the fluid is effused Why secretions differ from each other A pt The process considered chemically , ® a Microscopic globules of the secretions ke =
2. Of the influence of the nerves on secretion
3. Of the changes of which secretions are susceptible Antagonism of the secretions
A. Of the discharge of the secretions ss Structure of the ducts,—their contractility
SECTION IV.
Of digestion, chylification, and the excretion of the decomposed effete matters.
CHAPTER 1.—Of digestion in general. The food ss = si 4 477 Most simple nutritive substances, aiae er siniil if 25 ‘78 Nutritive principle of food a € d she 479 Azotised and unazotised aliments Gs 3 : : 480 Necessity of a varied diet ee : E +e ws - 482 Dr. Prout’s classification of alimentary substances Z ‘ 8 463
Xvi CONTENTS,
Sensations connected with digestion, appetite and satiety, &c. Hunger and thirst oe i as a Effects of long fasting .. z
CHAPTER 11.—Of the digestive organs,
a. Of the different forms of the alimentary canal In the invertebrata TE: In the vertebrata tie E a ce Influence of the nature of the food on the organisation
b. Of the coats of the alimentary canal ` The mucous membranes,—its glands The muscular coat,—the serous coat
ee eo
ee ee oo eo
CHAPTER 111.—Of the movements of the alimentary canal. How far subject to the will VAs The sucking of new-born children 1. Deglutition,—its three stages ee Influence of the epiglottis in deglutition 2, Movements of the esophagus %
3. stomach during digestion 4, Ruminating 5. Vomiting re Ag Mode of action of emetics 6. Motions of the intestines
CHAPTER 1v.—Of the secretions poured into the digestive canal. The saliva,—its chemical composition The gastric juice = Fe Its analysis .. ee oF The bile—biliary canals of insects “ime re Is the bile secreted from venous or from arterial blood ? Its properties and chemical composition .. Bile of serpents, fishes, &c.—discharge of the bile The pancreatic juice,—its composition Ey Secretion of the intestines F: Fi
CHAPTER v.—Of the changes which the food undergoes in the alimentary canal,
a. Change effected by the saliva ve we ue b. Change effected in the stomach—action of the gastric juice Dr. Beaumont’s observations Fà = sè ee Table showing the time required for ee digestion of draen kinds of food Gas of the stomach Fs S Composition of the chyme B: Digestion in ruminants—in birds zi Theory of digestion, —theory of fermentation Theory of Schultz y as : 1. Is there a gastric juice ? ee š ri x : 537 2. Is the gastric juice a solvent for food out of the body ? s E 537 Experiments of Spallanzani, Tiedemann, and Gmelin, Dr. Berana and others 537 3. Are the solvent principlesin the gastric juice acids, or other unknown substances? 540 Experiments of Tiedemann and Gmelin, and Beaumont iu Mueller mi = Researches of Eberle, Mueller, and Schwann
CONTENTS.
Artificial digestive fluid 55 ae we
Nature of the digestive process .. ae A
Chemical properties of the digestive principle or “ pepsin”
Its action on casein im ne mA er
Substances not dissolved by the “pepsin?” .. | oe
Influence of the nerves and of electricity on digestion
Of the changes which the chyme undergoes in the small intestine
Influence of the bile on the chyme oa 5 a
Effects of ligature of the bile duct : 56 oe d. Changes which the ingesta undergo in the AA intestine An
Gaseous matters in the intestines
The fæces KA
CHAPTER vi.— Of chylification.
Absorption of the chyle . oe a : Properties of the chyle .. +. . 36 Differences in the chyle, arising koia variety of food oo The chyle ee eee of the white colour of the chyle .. Its red colour .. : oe
The fibrin of the Hie, source ahs
The serum,—its composition : s
Comparison of the chyle with ERR —with blood
Effect of ligature of the thoracic duct a a Re,
CHAPTER vir.—Of the function of the spleen, the supra-renal capsules, the thyroid, and the thymus glands.
a. The spleen,—its structure ee Function of the spleen .. oe b. The supra-renal capsules,—their structure Function of the supra-renal capsules 3 c. The thyroid body, —its structure 7 d. The thymus gland,—its structure ct Function of the thymus ae CHAPTER vitr.—Of the elimination of the effete decomposed matters. Cause of excretion,—relative quantity of the excretions =. Excretion of foreign matters = a 56 A 1. Cutaneous exhalation and perspiration sa P Their quantity under different circumstances D Their composition = An m Object of the cutaneous secretion x 2, The secretion of urine Properties of the urine . a. Essential constituents of the ur ine i 1. Urea .. si i ži _— its composition, —its artificial production _—-— present in the blood —— its source The urine in diabetes T Lony , Uric acid ,—its composition In the urine, —its red colour Relation of uric acid to urea Urine of different animals
xviii CONTENTS.
Urine in diseases,—source of the uric acid ..
. Hippuric acid, its propertiesand composition
. Lactic acid ka a RE yk
. Salts of the urine a ee ae ms Proportion of solid matter of urine under Sees circumstances
. Accidental constituents of the urine ea s
. Matters which are not excreted with the urine R
excreted with the urine, but in an altered wk
unchanged
Diuretics i a8 A m
Office of the renal excretion a zs a oe
Action of alkaline carbonates, and the salts of vegetable acids on the urine Time which elapses before ingesta reach the urine «o = Discharge of the urine S x ee ig
BOOK III.
Physiology of the nerves»
SECTION. I.
Of the properties of the nerves generally.
CHAPTER 1.—Of the structure of the nerves. a, Of the principal forms of the nervous system Type of the radiata ws s3 mollusca s ar articulata .. = 3
. Of the minute structure of the nervous substance Primitive fibres of the nerves si Primitive fibres of the brain Grey fasciculi in the nerves m Course and arrangement of the nervous fibres : Mode of termination of the nervous fibres oe Grey substance of the brain and spinal cord, and ganglia Ganglia,—their classification fs CHAPTER 11.—Of the excitability of the nerves , Action of stimuli on the nerves... F mechanical stimuli s ~———— temperature > chemical stimuli ——_—— electric stimuli
CONTENTS,
2. Of the changes produced in the excitability of the nerves by stimuli 1. Renovating stimuli ..
2. Alterant stimuli oy
Mode of action of narcotic poisons
Dependence of the nerves on the brain and spinal cord
CHAPTER 111.—Of the active principle of the nerves Comparison with electricity oe 35 Do electric currents exist in the nerves? ..
SECTION IL.
Of the nerves of sensation, the nerves of motion, and the organic nerves.
CHAPTER 1.—Of the sensitive and motor roots of the spinal nerves 640 Experiments demonstrating their properties a E A 642
CHAPTER 11.—Of the sensitive and motor properties of cerebral nerves 646 The fifth pair sz re se F; 647
- The glosso-pharyngeal .. . ; : 650 The vagus and spinal accessory .. = ot 7 652 The ninth pair ; p z & 3 657 The third, fourth, and sixth nerves na i ae F 658 The facial nerve ne ig os a Ne ar 659
CHAPTER 111,—Of the sensitive and motor properties of the ganglionic or sympathetic nerve = 5 Se gf ie! 661 Sensitive properties of the sympathetic fer ae 661 Motor properties of the sympathetic y 7 ade 3 663 Composition of the sympathetic .. oe == 664
CHAPTER tv.—Of the system of grey or organic fibres, and its properties 667
ae = E 668 - Grey fibres in the ganglionic or sympathetic nerves .. Se a 672
. Functions of the grey or organic fibres ahs Be 2 ee 673
. Grey fibres in cerebro-spinal nerves es
CHAPTER v.—Of motor, sensitive, and organic nerves in the nervous system of invertebrata. Z ‘is i Se = 675
SECTION III. Of the mode of propagation of nervous action in different nerves.
Theories of nervous action Rate of nervous action M. Nicolai’s observations
CHAPTER 1.—Of the laws of action of motor nerves a. Of the laws of the transmission of nervous influence in motor nerves b. Of the associate or consensual movements... es = Motions of the iris iv Theory of the consensual movements
CONTENTS.
CHAPTER 11.—Of the laws of action of sensitive nerves
. Of the laws of transmission of nervous influence in sensitive nerves Theory of sensation .. : ee The sensations referred to amputated Fate Pg Transposition of sensations pi &
. Of the radiation of sensations si i Of the coincidence of sensations vi Distinctness of sensations in different parts Single vision with the two eyes .. +
CHAPTER 111,—Of the reflected motions Different explanations of them ., be Dependent on the spinal cord A ; State of irritability of spinal cord, —how mikaa
. Local reflected motions E z Eki =
. Reflected motions of systems of — x
. Reflected motions of muscies of entire trunk from aane of mucous membranes
3 from irritation of nerves Dr. Hall’s observations ve The reflected motions attended with ee iigh not neea Paths of transmission of the influence from the sensitive to the motor
nerves Ge ar ot ar ae Theory of the reflected motions X 3
CHAPTER Iv.—Cause of the different action of the sensitive and motor nerves Ri one go e u = A CHAPTER v.—Of the laws of action of the sympathetic . Of the actions of the sympathetic in involuntary motions
Reflex actions of the sympathetic Influence of the ganglia sy
. Of the sensitive functions of the sympathetic Influence of the ganglia a 4
. Of the organic functions of the sympathetic Influence of the ganglia i CHAPTER VI.—Of the sympathies i I. Sympathies of the different parts of a tissue re II. Sympathies between different tissues 2i °° III. Sympathies of individual tissues with entire or gans IV. Sympathies between different organs 5 x: V. Sympathies of the nerves ake . ee
CONTENTS.
SECTION IV. Of the peculiar properties of individual nerves.
eo ee
CHAPTER 1.—Of the nerves of special sense Nature of sensation
The nerves of the different senses cannot jara shes ones of each other The fifth the nerve of taste
Influence of the fifth on the other senses
CHAFTER 11.—Of the peculiar properties of other nerves Of the motor nerves of the eye and iris ae Movements of the iris dependant on the third nerve ar
Comparative anatomy of the motor nerves of the eye and of the lenticular ganglion
Of the fifth nerve si Its communications with the EEE with the lenticular ganglion
with the spheno-palatine ganglion
: with the otic ganglion
Comparative anatomy of the fifth nerve
' Of the facial nerve TA a
Its comparative anatomy ; oe Connection of the facial with the Fanti hia tympani Of the glosso-pharyngeal nerve ..
Its comparative anatomy
Of the vagus S
Its comparative anatomy
Of the spinal accessory
Of the ninth pair AS
Its comparative anatomy .
Arrangement of the cerebral nerves into pr ine and derwative Of the sympathetic nerve x Z
Its peculiarities in different animals
SECTION V.
Of the central organs of the nervous system.
CHAPTER 1.—The central organs of the nervous system considered generally ae ss ae Ag ka z Functions of the nervous centres Ac oe = 5 Formation of the nervous centres 2s ee > Functions of the nervous centres in the lower animals Relative size of the nervous centres in different vertebrata
CHAPTER 11.—Of the spinal cord Ss
Its structure .. = n . The spinal cord a conductor of nervous action
Mode of origin of the spinal nerves
Relation of the spinal cord to the nerves.
xxii CONTENTS.
Properties of the anterior and posterior columns of the cord ., Properties of the white and grey substances of the cord a Resemblances between the spinal cord and nerves ., a
2. The spinal cord as a part of the central organs of the nervous system The spinal cord a reflector of centripetal impressions upon motor nerves
does not perceive sensations P Fe D
a source of motor power
propagates any change in its state very readily
is the source of the force of our movements
is the source of the sexual power
has an influence over organic processes
CHAPTER 111.—Of the brain .,. an
1, Comparative anatomy of the brain
2. Of the powers of the brain and the mental oe generally Relative size of the brain in different animals and man The brain, and no other organ, the organ of the mind Influence of the passions on the different viscera The mental principle not confined to the brain ae oe Latent state of the mind in the generative fluids and germ ae In idiotcy and insanity, &c. the brain only, not the mind, affected Is the mind identical with the vital principle ? i oe The doctrine of materialism ie . : oe Source of the multiplication of the mental ete in Se ein
3. The medulla oblongata Its structure Its functions .. ae
4. The corpora quadrigemina Their functions
5. The cerebellum Its functions Its relation to the necks instinct
6. The cerebral hemispheres Their functions a z Gall’s doctrine of cranioscopy or raio :
7. Propagation of nervous action in the brain and spinal cord, Sources of paralytic affections and of convulsions = a a Parts which influence the opposite and those which influence the same side
of the body Varieties of paralysis ed voniai
A.l. Paralysis from lesion of the spinal cord 2. the brain z
B. 1. Convulsions from affections of nerves 2. of the spinal cord 3. of the brain sige Pa Rotatory motions of animals from lesions of certain parts of the brain Rotatory sensations—Vertigo—Purkinje’s experiments =
an gant) Boe
MTE Pie
sone “Tee
Pee
Fg. 16.
Tondon:Taylor & Walton, Upper Gower Stre et,1837.
EXPLANATION OF THE PLATE.
[Fig. 1 to 6 represent the particles from the blood of different animals, all magnified about four hundred diameters.
Fig. 1; see page 99 to 109. Red particles of human blood, after Wagner.
Fig. 2. Red particles of the blood of the common fowl, a, Ordinary appearance when the flat surface is turned towards the eye ; b, appearance which is sometimes presented by the particle when in the same position, and which suggests the idea of a furrow surrounding the central nucleus ; c, d, different appearances of the particles when seen edgeways.
Fig. 3. Red particle of the frog.
Fig. 4. ———-— of the squalus squatina, after Wagner.
Fig. 5. — of the lophius piscatorius, after Wagner.
Fig. 6. Particles from the blood of the scorpion, also copied from the figure given by Wagner, who has erroneously asserted. (as cited at page 109) that the particles of the blood of all invertebrate animals are roundish, while in the larve of several insects— the dytiscus, libellula, and ephemera, for example—the particles circulating in them can be distinctly seen to be much elongated and flattened. In other transparent larve in which the action of the heart and its valves are very easily distinguished, no par- ticles are visible.
Fig. 7. Lymphatics of the glans penis and prepuce, after Breschet. a, Superficial layer of lymphatics on the glans; b, the same on the prepuce; c, deep layer on the glans ; d, large lymphatics surrounding the base of the glans. (See page 264.)
Fig. 8. Lymphatics of the mucous membrane of the stomach, after Breschet. a, Superficial layer ; b, deep layer.
Fig. 9. One of the intestinal villi, with the commencement of a lacteal after Krause. (See page 269.)
Fig. 10. Lamina of the cartilage of bone cut from a transverse section of a cylindrical bone of the human subject, as viewed with the microscope, copied from Miescher’s figure. a, One of the canals of Havers surrounded with concentric lamelle ; 6, com- munication between two of the canals ; c, lamelle that form larger circles around the medullary cavity. (See page 378.)
Fig. 11. A longitudinal section of the cartilage of bone, after Miescher. a, One of the canals of Havers cut longitudinally ; 6, a similar canal more deeply seated in the lamina of cartilage.
Fig. 12. A transverse section of one of the canals of Havers, with its concentric jamelle more highly magnified, (about three hundred times, ) showing the radiated ap- pearance produced by the short lines that partly traverse the substance of each lamella.
Fig. 13. Osseous ‘corpuscules, very much magnified, with the ramifying lines that issue from them, after Muller, in a paper appended to Miescher’s dissertation, De in- flam. oss. eorumque anat, (See page 379.)
Fig. 14. Thin lamina from the ossifying epiphysis of the humerus of a foetal calf, taken from a section made perpendicularly to the ossifying surface, as shown in the outline sketch of the bone, and highly magnified. æ, Uniform granular cartilage ; b, cartilage nearer to the ossifying surface, the corpuscules aggregated into cells or columns ; ¢, bone shooting into the cartilage.
Fig. 15. Thin lamina from a transverse or slightly oblique section of the ossifying surface. (See the figure of the bone.) a, Cartilage with the corpuscules in groups ; b, the bone enclosing cells or tubes. This and the preceding figure are copied from draw- ings lent to the Translator by Dr. Sharpey. (See page 382.)
Fig. 16 represents the appearance in thin lamine of the cartilage of the epiphysis taken from near the ossifying surface, and magnified, but less highly than the two preceding figures, a, a, Sections of the canals in which blood-vessels run ; 6, commu- nication between two of these canals; the corpuscules are seen to be collected into groups which are arranged in a radiated manner around the canals, (See page 383.) ]
CORRIGENDA ET ADDENDA.
Page 110, in the note, for “ Dr. Gordon, also, in his Syllabus of Lectures on Ana- tomy,” read, “ Dr. Gordon, also, in his Outlines of Lectures on Human Physiology, published in 1817, page 60.” (‘The paragraph in Dr. Gordon’s Outlines referred to in the note is the following : Venous blood “is discovered by the microscope to consist of two parts ; a transparent fluid, and red particles. a, The transparent fluid begins to suffer a species of decomposition called coagulation the moment it escapes from the veins of the living body, and therefore cannot be examined in its natural state. Its properties judged of by an examination of the products of this decomposition. These products are serum and fibrin.’’)
Page 160. Fig. 5. The vessels distinguished by the cypher 8 are veins which return the blood from the muscles of the back, and pour it into the afferent renal vein (9).
Page 252. Heading of page ; for ‘ Absorption of the skin,” read “ Absorption by the skin.”
CORRIGENDA.
Page 87, line 4, for “ Dr, Marshall Hall,” read “ Dr, E. Hale.”
Page 212, the paragraph at line 28, ‘« This can be seen distinctly in the water sala- mander.”’ to precede, instead of following, the paragraph, “ At the extremity of each of the villi,” &c. at line 26,
Page 477, lines 14 and 16, for “ Nova Scotia,” read “« New Caledonia.”
Page 486,-line 27, for “ animals are best able,” read “ animals are least able.”
Page 526, line 3, for “ goat,” read “ horse.”
PROLEGOMENA
ON GENERAL PHYSIOLOGY.
PuystoLoey is the science which treats of the properties of organic bodies, animal and vegetable, of the phenomena they present, and of the laws which govern their actions. Inorganic substances are the ob- jects of other sciences, — physics and chemistry.
In entering upon the study of physiology, the first point to be ascer- tained regards the distinctions between these two great classes of bodies—the organic and the inorganic,—and the following questions suggest themselves for discussion. Do organic and inorganic sub- Stances differ in their material composition? and since the phenomena presented by these two classes are obviously so different, are the forces or principles on which they depend, also different; or are the forces which give rise to the phenomena of the organic kingdom merely modifications of those which produce physical and chemical actions?
1. Of Organic Matter.
Nothing analogous to sensation, nutrition, or generation, is presented by inorganic bodies, and nevertheless the matter which composes or- ganic bodies consists of precisely the same elements as inorganic matter. In examining the composition of organised bodies, it is true, we meet with substances—the proximate principles, or principes immediats—which are peculiar to organic bodies, and cannot be produced artificially by any chemical process; such are fibrin, albumen, gelatin, &c. But all these substances may be reduced by chemical analysis to the same simple elements which constitute minerals. Of these simple substances, all en- tering into the composition of inorganic bodies, there are fifty-two. In organic bodies there have been discovered but eighteen.
The elementary substances which are met with in plants are :
. Carbon,
. Oxygen, their most essential components. . Hydrogen,
. Nitrogen, found less frequently.
. Phosphorus, 2 . . principally in vegetable albumen and gums, especially . Sulphur, $ in the tetradynamia, combined with nitrogen,
- Potassium, . _. almost universally. . Sodium, . . principally in marine plants.
ORGANIC MATTER.
9. Calcium, found almost universally. 10. Aluminium, wes rarely
11. Silicium.
12. Magnesium, occurring rarely.
13. Iron, ? 14, Manganese, §
15. Chlorine.
16. Iodine, 17. Bromine,
frequently.
« in marine plants.
The same substances, with the exception of aluminium, are met with likewise in the animal kingdom. Here sodium is more frequent, the potassium less frequent than in plants; iodine and bromine occur in some marine animals.
In man and the higher animals the components are :
. Oxygen. . Hydrogen. . Carbon. . Nitrogen. . Sulphur, met with principally in the hair, albumen, and brain. . Phosphorus, í a > . in the bones, teeth, and brain, . Chlorine, . Fluor, . Potassium, 10. Sodium, 11. Calcium, 12. Magnesium, I es ? found in the hair.
15. Iron, . . in the blood, pigmentum nigrum, and crystalline lens.
in the teeth and bones.
[Copper is also numbered among the substances which sometimes enter into the composition of organic bodies. Beecher asserts that he has found gold also in the ashes of tamarinds.* ]
The number of the elements which enter into their composition, consti- tutes, then, the first difference between organic and inorganic bodies. All the elementary substances found in the inorganic kingdom do not enter into the composition of organic bodies; some are even inimical to their life.
The mode in which the elements are combined forms a second dis- tinguishing character; and the peculiarity of organic matter depends probably on the following circumstances, first pointed out by Berzelius and Fourcroy.
1. In mineral substances the elements are always combined in a binary manner; thus, two elementary substances unite together, and this binary compound unites again with another simple substance, or with another binary compound. For example, carbonate of ammonia is
* Tiedemann’s Physiology, translated, with notes, by Drs. James Manby Gulley, and J. Hunter Lane, p. 6.
PECULIARITIES OF ITS COMPOSITION. 3
constituted of carbon, oxygen, hydrogen, and nitrogen, combined as fol- lows : aes ? unite to form carbonic acid, eee ammonia Nitrogen, $ R E T 5
which again unite to form carbonate of ammonia.
In minerals the elementary substances are never observed to combine three or four together, so as to form a compound in which each element is equally united with all the others. This, however, is universally the case in organic bodies. Oxygen, hydrogen, carbon, and nitrogen, the same elements which by binary combination formed inorganic substances, unite together, each with all the others, and form the peculiar proxi- mate principles of organic beings. These compounds are termed ternary, or quaternary, according to the number of elements composing them. Vegetable mucus, starch, and adipose matter are ternary compounds of oxygen, carbon, and hydrogen: gum, albumen, fibrin, animal mucus, and resin are quaternary compounds, their fourth ingredient being nitrogen.
‘A doubt has recently been thrown upon this theory of the composi- tion of organic substances, especially with respect to some particular products, such as alcohol; but there is still great probability in its favour, and more particularly in reference to the higher organic com- pounds, such as albumen, fibrin, &c.*
It must at any rate be admitted, that the mode in which the ultimate
elements are combined in organic bodies, as well as the energies by which the combination is effected, are very peculiar ; for, although they
may be by analysis reduced to their ultimate elements, they cannot be regenerated by any chemical process.
* Berard, Proust, Dobereiner, and Hatchett believe that they have succeeded in producing organic compounds by artificial processes; but their results have not been sufficiently confirmed. Woehler’s experiments afford the only trustworthy instances of the artificial formation of these substances. Woehler discovered that a watery solution of ammonia, after being saturated with cyanogen, contained a considerable quantity of oxalic acid, Again, in the preparation of potassium from charcoal and carbonate of potash, a black mass passes over with the metal, which, when treated with water, yields a large proportion of oxalic acid. Oxalic acid, however, is now regarded as a binary compound of carbon and oxygen ; the fact that it undergoes decomposition when its water of crystallization is extracted, is no proof to the contrary, for nitric acid also is decomposed by the extraction of the last portion of its water. See Mitscherlich’s Chemie, p. 416. Woehler also finds, that urea is obtained in place of cyanite of ammonia, when a solution of chloride of ammonia is poured over freshly precipitated cyanite of silver, chloride of silver being formed at the same time. Urea is also form- ed in the decomposition of cyanite of lead by solution of ammonia. The solution at first contains cyanite of ammonia; but, by evaporation of the fluid, this salt is convert- ed into urea. In the same way, also, when cyanous acid is mixed with water or liquid ammonia, cyanite of ammonia is first formed, and thence urea. — Gmelin’s Chemie, vol. iii. p. 6; Berzelius, Thierchemie, p. 356. Urea, however, can be scarcely considered as organic matter, being rather an excretion than a component of the animal body. It has not perhaps the characteristic properties of organic products.
ee
ORGANIC MATTER.—PUTREFACTION.
2. Another essential distinction pointed out by Berzelius is, that in organic products the combining proportions of their elements do not ob- serve a simple arithmetical ratio. Thus, for example, there is a large number of different kinds of fatty matters which Chevreul has examined, and many of which, according to his experiments, differ only by frac- tional parts in the numerical proportions of their atoms.
3. Organic bodies consist chiefly of combustible matter, which, both in animals and vegetables, is constituted (the acids excepted) of carbon and hydrogen, combined with oxygen in quantity not sufficient to saturate the other elements.*
Tendency to decomposition —The matter forming organic bodies has a constant tendency to undergo decomposition ; it is only the continuance of life which preserves it. But even during life the balance, which maintains its elements in their peculiar combination, may be destroyed by the agency of certain simple inorganic bodies, or binary compounds of these, as we witness in the burning of parts of the living body. At some period or other this change necessarily ensues spontaneously in every living being ; the state or influence which maintains the elements in their peculiar combinations becomes more and more feeble, and is, at length, no longer able to counteract the tendency of these elements to form binary compounds among themselves, and with other simple sub- stances in the atmosphere around them. Organic matter is thus anni- hilated, and with it the organised being of which it formed part. And in ceasing to present the phenomena of life, it falls under the influence of the laws which govern the formation of chemical com- pounds, presenting the phenomena of fermentation and putrefaction, a foul smell being produced when the substance contained much nitrogen.
/ Chemical compounds, we know, are regulated by the intrinsic properties
| and the elective affinity of the substances uniting to form them; in
| organic bodies, on the contrary, the power which induces and maintains
\ the combination of their elements does not consist in the intrinsic pro- perties of these elements, but is something else, which not only coun- teracts these affinities, but effects combinations in direct opposition to
them, and conformably to the laws of its own operation. Light, heat, and electricity, it is true, influence the compositions and decompositions going on in organic bodies, as they do those in inorganic bodies; but nothing justifies us in regarding without further inquiry any one of the imponderables,—namely, heat, light, and electricity, —as the final cause of vital actions.
After the cessation of life, organic substances always undergo decom- position, if the conditions necessary for the exertion of chemical affinity
* These distinctive characters of organic matter will be found more fully detailed in
the classical text-books, of chemistry by Berzelius and Gmelin, and of anatomy by Weber in his fourth edition of Hildebrandt’s Anatomie des Menschen, vol. i.
MINERAL COMPONENTS OF ORGANIC BODIES. 5
are present. The products of this decomposition are nitrogen and hydro- gen, (which partly escape in a free state,) water, carbonic acid, carburet- ted hydrogen, olefiant gas, ammonia, cyanogen, prussic acid, phosphuret- ted hydrogen, and hydrosulphuric acid ; while in some cases the elements reunite in different proportions so as to form a new organic compound, as , in the production of sugar from starch in the saccharine fermentation. Sometimes from one organic substance two new compounds are gene- | rated,—one organic, the other inorganic,—as in vinous fermentation, | during which carbonic acid and alcohol are formed from sugar. Decom-/ position does not commence in the bodies of animals and plants immedi- ately after their death. This Gmelin explains by supposing that the conditions necessary for the exertion of elective affinity are not then
present, just as several inorganic substances require a certain tempera-
ture for their decomposition.*
The conditions more or less necessary for the spontaneous decomposition of organic matter, are moisture, the access of atmospheric air, and a cer- tain temperature. ‘The first is absolutely necessary ; organic substances when perfectly dry do not undergo decomposition at the ordinary tem- perature of the atmosphere. Air is also often necessary, but not always; moist animal tissues suffer decomposition even when atmo- spheric air is excluded, although the presence of air facilitates putre- faction in the highest degree, even more than oxygen. A certain tem- perature is always necessary.
The gaseous products of the decomposition of animal matter, and of the human body in particular, are carbonic acid, sometimes nitrogen, hydrogen, sulphuretted hydrogen, phosphuretted hydrogen, and ammonia. Acetic acid is also formed, and sometimes nitric acid. The solid matter that remains, consists of the carbonaceous matters, which decompose more slowly, and the fixed mineral ingredients, earths, oxides, and salts, which with the carbonaceous matters form the soil (humus). Several parts of the bodies of man and animals immersed in water, or buried in certain situations, even without the access of water, undergo a peculiar change, being converted into a substance, named adipocire. Berzelius is of opinion, that the fibrin, albumen, and colouring matter of the blood, as well as the adipose matter, may be converted into this sub- stance; while Gay Lussac and Chevreul state that the fat, which can be extracted from fresh animal textures by chemical processes, equals in quantity the adipocire generated by putrefaction in water, and infer, therefore, that the fat merely is converted into adipocire, while the other tissues are destroyed.
State in which mineral components exist in organic bodies—The pro- portions in which the oxygen, hydrogen, carbon, and nitrogen are com- bined, seem to constitute the chief differences in the composition of
* Gmelin’s Chemie, vol. iii. p. 9. + See Weber loc. cit. vol. i. p. 70.
6 SALTS AND OXIDES IN ORGANIC BODIES.
organic substances. The organic compounds of these elements especi- ally, are ternary and quaternary, not binary. In what state the less abundant mineral ingredients exist in organic bodies,—whether they like- wise enter into the formation of ternary or quaternary compounds, or are merely mingled with them in the binary form,—is an important ques- tion which cannot at present be determined. Engelhardt has ascer- tained that the mineral ingredients can be separated from a watery so- lution of the colouring matter of the blood, and other animal matters, by means of chlorine. From this fact, and from the iron not being extract- ed by acids, Berzelius infers it to be probable that the iron in the blood is in the metallic state, not in that of oxide; for chlorine has a very strong affinity for metals, and not for oxides, for which acids on the other hand have a great affinity. Professor Henry Rose adduced some experiments which seemed to show that the iron was combined as an oxide with the animal matter, thus as an albuminate of the oxide; but Berzelius again rejects this idea, for in that case the oxide ought to be extracted by acids from the blood as it is from artificially formed albuminate of iron.*
Berzelius cannot decide in what form sulphur and phosphorus exist in animals; whether united with other simple substances to multiple. organic compounds, or combined with the ternary compounds of other simple substances so as to form secondary binary compounds, or
whether each of these substances, already in a binary form, is again combined with other substances. Vauquelin, by burning the fatty mat- ter of the brain, obtained a cindery mass, which contained so much phosphoric acid, that this latter substance by preventing the access of air arrested the combustion ; on removing the phosphoric acid by means of water, the mass again burned for a time, until more acid was form- ed upon the surface. From this circumstance we see, says Berzelius,+ that this cinder contains phosphorus in a fixed, not volatile state,—in a state hitherto unknown in inorganic nature.
Many circumstances, however, render it probable that several mineral substances in the binary form, as salts or oxides, exist in the animal body, either mixed or chemically combined with the animal matter. These circumstances are: 1. the appearance of minute micro- scopic crystals in the animal fluids simply evaporated; 2. the facility with which the mineral substances contained in plants vary with their situation, which could not be the case if the mineral elements existed in them merely as elements of the organic compounds ; 3. the facility with which salts, which enter the blood accidentally, are separated from
* [The arguments of Rose, Engelhardt, and Berzelius, on this point, are stated fully in the section on the Chemical analysis of the blood ; the translator, therefore, considered it unnecessary to give them here at length.]
+ Thierchemie, p. 16,
FORMS OF ORGANIG MATTER. rp
it in the urine; 4. that chloride of sodium can, as Autenrieth remarks, be separated from solid animal matter by mere washing; 5. the state of the phosphate of lime in the bones. Professor E. H. Weber shows clearly, that the phosphate of lime of the bones does not exist in them as phosphorus, oxygen, and calcium; but that itis in the state of a salt combined—perhaps only mechanically mixed—with the cartilagin- ous substance, since madder (rubia tinctorum), which has a strong afli- nity for phosphate of lime, but none for lime or calcium, is attracted, during the process of nutrition, by the bones from the blood of an ani- mal fed upon it; and, moreover, several acids decompose the salt of lime contained in the bones, and extract it without altering the form or com- position of the cartilaginous framework.*
Excluding from consideration the substances which in individual cases may be educt or product of chemical analysis, we may with Professor Weber regard those matters, which appear to be mixed in the animal body with the more essential proximate principles, as divisible in two classes.
The first class may consist of binary compounds of mineral substances only; such as phosphate of soda, phosphate of lime, phosphate of magnesia, carbonate of soda, carbonate of lime, muriate of potash, muriate of soda, fluoride of calcium, silica, oxide of manganese, oxide of iron, and soda.
In the second class are included binary compounds of organic with mineral or inorganic substances; such as the compound which the albumen is supposed to form with soda in the blood—albuminate of soda—and the salts of lactic acid—lactates of potash and soda.
The simplest forms in which organic matter appears, have now to be considered.
The first form is that of complete solution. ‘There are many fluids containing organic matter, in which no visible molecules can be discover- ed; such, for instance, is the serum of blood, until it is subjected to the influence of heat, galvanism, or different chemical agents. A part of the animal matter of the lymph and chyle is also in the state of solution.
The second form is the state of softness which the solid organised tissues present, and which is peculiar to organic beings. The tissues derive their properties of extensibility and flexibility from the water, which constitutes four-fifths of their weight; although they cannot be said to be wet, and do not impart their water to other substances so as to moisten them. This water appears, as Berzelius remarks, not to be chemically combined in them; for it is gradually given off by evaporation, and can be extracted at once by strong pressure between blotting-paper. When deprived of its water, animal matter becomes wholly insusceptible of vitality ; except in the case of some of the lower animals, which, as well as some plants, revive when again moistened.t
* Weber, loc. cit. p. 318, 340. + Berzelius, Thierchemie, p. 7.
8 ORGANIC MOLECULES.
According to Chevreul, pure water alone can reduce organised sub- stances to this state of softness; although salt water, alcohol, ether, and oil are also imbibed by dry animal textures. Moist animal tissues, by virtue of their porosity, allow soluble matters, which come into contact with them, to be dissolved by the water which they contain, and which fills their pores ; if the matters are already in solution, they are impart- ed by their solutions to the water of the tissues. Gaseous substances are taken up in the same way. Matters, also, which are contained in solution in one tissue, are rapidly imparted to other tissues which can dissolve them. The laws of the attraction of substances in solution and mixture, ‘the laws governing the uniform distribution of miscible fluids, are therefore also applicable in the case of moist animal tissues.*
Organic substances are during life never crystallized, and the excreted matters of animals which are crystallizable, viz. urea, lithic acid, and some fatty matters, are never found crystallized in the living tissues, although crystallized mineral substances are sometimes observed in the cells of plants.
The organic matter frequently appears in the form of microscopic molecules. ‘These organic molecules are observed partly in fluids : such are the red particles of the blood which in man measure from 370 tO zogo Of an inch, the globules of the chyle which measure aiyp of an inch according to Prevost and Dumas, and those of the saliva, which measure 37475 of an inch, according to Weber. The globules of coagulated albumen and fibrin are less distinct. Many even of the tissues of organised bodies, particularly of animals, appear to consist of molecules aggregated in the form of fibres, lamella, and membranes. These molecules are most distinct in the brain, and in the embryo, for instance, in the germinal membrane of the ovum; in other tissues, it is by no means certain that the appearance of mole- cules, observed under the microscope, is not an illusion produced merely by inequalities of the surface. The opaque part of the germinal membrane in the ovum of the bird is evidently composed of globules of considerable size, which are visible with a simple lens and are perfectly similar to the globules of the yolk: but the vessels which are already distributed through the germinal membrane are, according to my observations, formed of an incomparably finer matter; as are also the central transparent part of the germinal membrane, the area pellucida, and the embryo itself. It appears, indeed, that the germinal membrane is formed by the attraction and aggregation of the globules of the yolk; but all the parts developed in this germinal membrane are produced by solution of these globules, and conversion of them into a matter in which no elementary particles can be distinctly recognised, and of which the molecules must at any rate be beyond comparison more minute than the globules of the yolk and germinal membrane.
* See the observations on imbibition in the section on Absorption by the capillaries.
SOURCES OF ORGANIC MATTER. 9
The ultimate muscular fibre in the frog is five or eight times more minute than the red particles of its blood, and more minute even than the nuclei of these red particles; the thickness of the muscular fibre in the frog and in mammalia is nearly the same, while the size of the red particles of the blood in the two is very different. The diameter of the ultimate nervous fibre in mammalia is, according to my observation, twice or three times less than that of their blood corpuscules, and is greater than that of the nuclei of the blood corpuscules. In the frog, the primitive nervous fibre has only 4th the diameter of its blood cor- puscules, and is therefore much smaller than the nucleus of the blood corpuscule. I have not been able to satisfy myself that the nervous fibrils consist of globules arranged in a linear form. They certainly present successive inequalities, but these inequalities are not regular. In fine, this theory of the composition of tissues by the aggregation of glo- bules, which are supposed to be more than 5,1,5 of a line in diameter, is rendered exceedingly improbable by the discovery of Ehrenberg, that monads, which themselves do not measure more than p4p of a line, have compound organs. On account of the difficulty of distinguishing by the microscope between inequalities and globules, this theory still remains a mere hypothesis. At any rate, the organic molecules are merely the most minute forms in which the compound organic matter appears ;
they are not the atoms of the organic combination.
Source of organic matter.—It is only in organic bodies themselves, that the peculiar force which animates them is observed. It is manifested only in the organic compounds produced in these bodies; the mere accidental coming together of the elementary components is not capable of producing organic matter. Fray, it is true, asserts that
he has observed the formation of microscopic infusoria in pure water ; and Gruithuisen says, that he has seen a gelatinous membrane form in infusions of granite, chalk, and marble, and infusory animalcules sub- sequently appear in this membrane. The fact observed by Retzius* is also remarkable; namely, that a peculiar kind of conferva was gene- rated in a solution of muriate of barytes in distilled water, which had been kept half a year in a bottle closed with a glass stopper. But, in these remarkable cases, it is certain that either the vessels, or the water, contained organic matter, in however small quantity; and, according to the experiments of Schultze, the most minute particles of organic mat- ter are sufficient under favourable circumstances to produce the pheno- mena which have been regarded as instances of equivocal generation. Even animals themselves have not the power of generating organic ` matter out of simple inorganic elements or binary compounds; they grow by the assumption of matter already organised, whether animal or vege- table ; they have the power of preserving organic compounds and of con- verting one into another, but they cannot produce them, Plants, on
* Froriep’s Notizen, v. p. 56,
10 EQUIVOCAL GENERATION.
the contrary, seem to be able not merely to assimilate the organic matter of animals and plants, but also to generate them from simple elementary bodies and compounds of these, such as carbonic acid and water, although the presence of some organic matter in the soil, in which plants grow, is necessary. It seems impossible to deny this production of organic mat- ter from inorganic matter by plants; for, unless such were the case, the nutriment on the earth would be constantly decreasing, since animal and vegetable matters are being incessantly converted by combustion, putrefaction, &c. into binary compounds.
The organic matter formed by plants, or that contained in plants and animals and modified by them, is capable of again forming a part of other living beings, when taken into them and subjected to their vital forces. In this manner all the organic matter which is spread over the surface of the earth, originates in living beings: death, that is, the ex- tinction of the power which produces and maintains organic compounds, annihilates the individual; while the organic matter which formed this individual, while it is not reduced to binary compounds, is still capable of receiving new life, or, in other words, of nourishing other living bodies.
Equivocal generation.—The ordinary mode of production of organic beings is from others of the same species, by ova or shoots. But it must be inquired, whether the organic matter left after the destruction of one living body can, under certain circumstances, generate living bodies of another kind; whether it is capable, not only of nourishing bodies already living, but also of continuing its own life in a modified form ; whether, in fact, under certain conditions,—namely, under the influence of atmospheric air, water, and light,—small microscopic animals, the infusoria, and under other conditions the simplest plants, forming mould, are generated from this apparently dead organic matter.
In a more extended sense the ancients, especially Aristotle, had admitted this equivocal generation, this spontaneous formation of animals; for they had an old tradition, that the lower animals, insects and worms, were generated during putrefaction. This opinion was still maintained among the other superstitions of natural his- tory and medicine even in the seventeenth century. At that period Redi wrote his “Experimenta circa generationem insectorum,” in which he proved that all the instances of equivocal generation, which the ancients had adduced, were erroneous; that all these worms and insects were produced from ova which had been previously deposited. His proofs were convincing, and from that time no well-informed natu- ralist believed in the fable of generation by putrefaction; so that the proverb “ Omne vivum ex ovo,” retained its force. Subsequently, how- ever, Needham* pointed out, that although no insects are produced by putrefaction, yet that, during that process, minute microscopic animals till then unknown are generated. If water is poured over animal or
* Nouv. Observ. Microscop. and “ New Microscopic Discoveries,” London 1745.
EXPERIMENTS OF VARIOUS ENQUIRERS. ll
vegetable substances, and the infusion exposed to air and light at the usual temperature of summer, after a few days the organic matter will have undergone partial decomposition, being in part converted into other organic matters, partly reduced to globules, and in part dissolved; and there will appear in it either mould, or those microscopic animals, in which Ehrenberg has discovered a very complicated organisation.
Since the time of Needham, our knowledge of this subject has been extended by the observations of Wrisberg, O. F. Müller, Ingenhouss, G- R. Treviranus, Gruithuisen, and Schultze.
Wrisberg* observed, that no animalcules are produced when atmospheric air is excluded, for instance, when the surface of the infusion is covered with olive oil, They are generated by an infusion of any animal or vegetable matter which contains nothing acrid or acid, and nothing which would prevent putrefaction. The development of infusoria com- mences as soon as a certain degree of decomposition with escape of gas has taken place. , From this time a large number of microscopic mole- cules are seen in the infusion ; these molecules are sometimes diffused in it, sometimes form a kind of membrane at its surface, and are produced. by the dissolution of the organic matter. Fray and Burdach+ state, that infusory animalcules are also generated in an atmosphere of hydrogen and nitrogen.
Spallanzani and several other physiologists attacked this theory of the equivocal generation of animalcules. Spallanzani{ explained the pro- duction of these animals by supposing ova to have been present in the fluid, and to be developed by the influence of warmth, water, air, and light. This physiologist’s own experiments, however, show that organic substances do not lose their property of producing animalcules by being boiled, and that distilled water is as well adapted for making the infusion as other water. Besides, Spallanzani’s experiments merely prove that atmospheric air is necessary for the development of these animalcules ; and that, when bottles filled with infusions, and hermetically closed, were exposed for an hour to boiling heat in vessels filled with water, no ani- malcules were afterwards discoverable in these infusions. Spallanzani also found that the animalcules differ according to the nature of the infusion. From experiments with the seeds of the water-melon, gourd, hemp, and millet, it resulted that the number of the infusoria is greater when the germ is in the progress of growth, than when the seed is just germinating, and that the number diminishes as the seed decays. The smaller kinds of animalcules were succeeded by larger, until, after a certain time, the power of developing them seemed to be lost. The infusory animalcules from uninjured seeds were said to be larger than those from pulverized seeds. They were generated from flour quite as well as from seeds merely bruised. If, however, the starch of the flour was separated from the
* Observ. de Anim, Infus. + Burdach, Physiologie, t. i. į Physical. und Mathem. Abhandl.
12 EQUIVOCAL GENERATION.—EXPERIMENTS ON.
gluten, and an infusion made of each of these substances separately, very few animalcules, or none at all, were developed in the infusion of starch, while in that of the gluten a host of living animals were seen. In infusions of barley, Indian wheat, beans, lupin-seeds, rice, and linseed, no animalcules were developed.* But since the genera and species of infu- soria are as determinate as those of higher classes of animals, and since Spallanzani has not particularized the differences of form of his infusoria, since moreover the forms of the infusoria in the different stages of their development are not known, Spallanzani’s experiments lose much of their weight in reference to his discovery of perfectly different animal- cules in the infusions of the gourd, chamomile, sorrel, corn, and spelt.
Treviranus+ has, by his numerous and more accurate experiments, given a much greater importance to the hypothesis of equivocal genera- tion. The following are the grounds of his arguments:
1. Infusions, with the same water, of different organic substances,—for instance, cress-seeds and rye,—give rise to different animalcules.
2. Light has a very great influence on the process of equivocal generation. Thus, the green matter of Priestley, which is remarkable for its property of exhaling oxygen, is produced only under the influ- ence of light; when water, particularly spring-water, is exposed to the sun in transparent vessels, whether open or close, this matter appears in the form of a greenish crust consisting of round or elliptic granules, in which crust at first -the slight motions of single molecules are discover- ed, and afterwards transparent threads moving irregularly. These changes have been most fully observed by Ingenhouss.{ According to Professor R. Wagner, the green matter of Priestley consists of the remains of green animalcules, the euglena viridis and others, which have died. In that case the moving threads would be independent beings, distinct from the green matter, and Ingenhouss would have committed the error of regarding different kinds of simple beings as different states of the same molecules.
3. The entozoa and the spermatozoa, bodies with tails and spontaneous motions, which are seen by the microscope in the seminal fluid, even of invertebrate animals, seem to afford arguments for the spontaneous origin of living beings in organic matter.
4. 'Treviranus found in his own experiments that, under circumstances otherwise similar, different organic beings, namely infusoria or mould, are formed in different infusions; and he found that these differences did not depend on the water, but on the substances infused in it.
5. Treviranus observed that in one and the same infusion, under different accidental conditions, different animalcules were developed ; thus, from an infusion of the leaves of the iris with fresh spring-water, in a long vessel covered with linen, and exposed to the sun, infusory ani-
* Treviranus, Biologie, ii. pp. 279, 280. + Biologie, ii. p. 264—406. + Vermischte Schriften phys. medic, Inhalts. i
REMARKS ON THESE EXPERIMENTS. 13
malcules were generated; in another vessel, placed in another situation, the green matter of Priestley was formed. Thus also the products in the same infusion of rye with spring-water were different, when Treviranus placed a bar of iron in one of the vessels. This result seems to agree with that of Gleditsch, who found that in separate portions of melon covered with muslin, and placed at different heights, the various living organic sub- stances, namely mould, byssus, and tremelle, were produced in different proportions. To this might be added, that Gruithuisen states that he has found perfectly different animalcules in infusions of pus and mucus.
From all these facts Treviranus has inferred, that throughout all nature there exists an absolutely indecomposible, indestructible (?) organic matter which is constantly active; which gives life to every thing living, from the byssus to the palm, and from the point-like infusory animalcule to the monsters of the deep; and which, in its essence un- changeable, is constantly changing its form: that this matter has itself no proper form, but is capable of assuming every form of life ; that it receives a determinate form only under the influence of external causes, retains this form only during the continuance of these causes, and takes another form as soon as other causes act upon it. According to Wrisberg and others, the animalcules are formed from particles which separate from the substance infused, and which gradually begin to move; while Gruithuisen* says, that they appear first in the solution of extractive matter obtained by the action of the water on the infused substance. Professor Schultze + says, “I have never seen a globule of blood, or of milk, or of cerebral substance, begin to move about in their several infusions, as a monad, or become changed into one. Every single globule, by its solution, affords matter for the production of several hundred monads.” This last observation, however, does not agree with the results of measurement ; for Ehrenberg estimates the smallest visible monad at about -ypy of a line, that is =z455 of an inch; while the corpuscules of human blood are only 3455 — xs/yp of an inch in diameter, and the globules of the milk are still smaller. Schultze states that he has observed the conversion of dust-like particles of organic matter into infusoria; these particles in the water become, he says, in a few hours Surrounded by a turbid ring which extends until the particle is quite dissolved ; this ring separates into monads.
Equivocal generation not proved by these observations.—If we criticise the observations of these observers, we shall find that the mode in which the experiments have been performed do not leave the results free from doubt.
1. In the experiments made with boiled organic matter, in the air, it is not certain that the infusoria or mould did not arise from the dust of * Gruithuisen, Beiträge zur Physiognosie und Eautognosie. München, 1812, 8vo.
+ C. A. S. Schultze, Microscop. Untersuchungen über R. Brown’s Entdeckung le- bend. Theilchen in allen Körpern, und über Erzeugung der Monaden. Carlsruhe, 1824.
14 EQUIVOCAL GENERATION.
desiccated animalcules, or their germs, floating in the air. Perhaps, as Humboldt remarks,* when waters on the surface are dried up, the winds take up the germs of the simplest organic beings, which, being received by other water in the form of dust, are revivified, as in the well known and attested fact of the revivification of the wheel-animalcule, first observed by Spallanzani. The fact of the dust which floats throughout the air containing particles which swell when moistened, has very recently been applied by Schultze to explain the production of infusoria; he regards these particles as monads which have been dried, and which when moistened recover life. Schultze, however, does not consider this very frequent source of infusoria as the only one; he admits the conversion of organic substance into protozoa.
_ 2. The equivocal generation of infusoria is not better proved by the experiments in which boiled organic substances and common water were used; for the water may have contained the ova of infusoria, or animal- cules themselves, which have afterwards multiplied very rapidly at the expense of the organic matter in the infusion. The use of perfectly pure distilled water can scarcely be presupposed, for even water distilled five times may still contain organic particles.
3. Those who have experimented with fresh organic substances and distilled water, or even artificially prepared gases, cannot prove that the ova of animalcules, or animalcules themselves, were not in some way contained in the organic substance: the microscopic animalcules which © are known to exist in living tissues are indeed few, and the common globules of the organic fluids, such as those of the blood, have certainly no individual life; but mucus itself contains microscopic animals; the intestinal mucus of the frog, as well as the semen, contains animalcules, Baer has seen microscopic particles moving spontaneously at different spots in the muscles.+| The grain of wheat, and some varieties of agros- tis, often contain vibriones, which even after being dried recover their active life if moistened. Some animalcules also which are met with in other animals, but especially the epizoa, will continue to live when placed in water.
4. Lastly, although some experimenters should have employed organic substances long boiled, with distilled water and artificially prepared air at the same time, still the accuracy necessary for a sure result is neither probable nor generally possible, since every instrument used for changing the water ought to be absolutely free from particles of organic matter, and every cleansing is a source of errors.
Ethrenberg’s observations are opposed to the theory.—These remarks do not disprove the existence of the equivocal generation ; they merely show that it is scarcely possible to prove it by direct experiment. The inves- tigations of Ehrenberg, however, relative to the organisation of these
* In his Ansichten der Natur. t See Nov. Act. Nat. Cur. 13. 2. p. 594,
K EHRENBERG’S OBSERVATIONS. 15
animals and plants, which are supposed to be generated in this equivocal manner, have thrown new doubt upon the theory. In the first place Ehrenberg discovered the real germs of the fungi and mould.* The propagation of these organic bodies was thus established; it was shown that, by means of the germs or seeds of the mould, new mould can be produced, which rendered it probable that the cases of the unexpected production of mould arose merely from seeds, which had been diffused in the atmosphere or water, having then found the situation required for their development. With regard to the infusory animalcules, their com- plicated structure was first discovered by Ehrenberg; he found that the smallest monad dyp of a line in diameter has a complicated stomach, and organs of motion, in the form of cilia. In others he observed the ova, and the propagation by ova. This excited the greatest doubt with regard to those earlier observations, in which, the complicated structure of these animalcules being unknown, they were said to have been seen to ori- ginate in particles of the organic substance of the infusion. Ehrenberg has never succeeded in obtaining determinate forms of infusoria, accord- ing to the nature of the infusion ; and even by the most similar modes of performing the experiment, sometimes one, sometimes another set of animalcules were obtained. Ehrenberg believes that there are certain forms, of which the number is limited, which are most widely diffused ; the ova or individuals of these forms may exist in all waters, even in Some parts of plants, but perhaps only in the noxious parts ; and of these
forms different kinds may be much multiplied, according to the kinds of ova or individuals which were in the water, or were introduced into it. The increase of these animals appears to be extraordinarily rapid. A single wheel-animalcule, Hydatina Senta, which was watched for more than eighteen days, and which lives still longer, is capable of a four-fold in- crease in twenty-four or thirty hours. This rate of increase affords in ten days a million of beings. This, in some measure, explains the extraordi- nary number of infusoria in a drop of an infusion. Ehrenberg never ob- Served any animalcules in dew or rain; but he has found some in Africa and Asia as well as in Europe, in sea water as well as in river water, in the depths of the earth and at its surface. During their de- velopment, however, these animals seem to present many forms, and the forms dependent on the different stages of development of one animal- cule may be easily mistaken for examples of different species. . From these observations Ehrenberg concludes, that all infusoria are, like other animals, propagated from ova,—omne vivum ex ovo,—and leaves it un- decided whether the ova are, or are not, in part really the product of a generatio primitiva. t
x Nov. Act. Nat. Cur. t,x. See also Ness. v. Esenbeck Schilling in Kastner's Archiv. x. p. 429.
+ Ehrenberg in Poggendorf’s Annal. 1832. 1. 1832,
» Flora, 1826, p. 531; and
See also Wagner in the Isis for Wagener regards as certain, the transformation of infusoria into the green
16 EQUIVOCAL GENERATION.
Facets relating to Entozoa, favourable to equivocal generation.—The primitive formation of certain animals from animal matter, till then un- organised, is still best supported by the facts regarding the entozoa. A complete series of arguments in favour of equivocal generation rests upon the impossibility of explaining the first production of entozoa, without supposing a spontaneous generation. l. The immense majority of the intestinal worms are quite distinct in their organisation from all the beings which are met with out of the animal body. The similarity of some distomata to the planariz of fresh and salt water is only apparent. 2. A small number only of intestinal worms occur in different genera of animals. Thus the Tzenia of man is peculiar to him ; on the contrary, the Distoma Hepaticum, the hydatid of the liver, seems to be common to man, the hare, cow, camel, deer, horse, and hog; the thread-worm, Ascaris Lumbricoides, is common to man, the hog, ox, and horse. Most animals have their peculiar intestinal worms, differing specifically from those of others. 3. Many of these entozoa occur only in par- ticular organs. 4. Intestinal worms generally die when removed from the animal body. 5. They have been observed even in the embryo. 6. The fact of animals, which feed on vegetables solely, having never- theless their own peculiar entozoa, proves that these entozoa, or their germs, cannot be introduced with the food. In carnivorous animals this introduction of the entozoa from without can be admitted in very few cases only; such are the facts of the Echinorhynchus of the field-mouse having been sometimes found in the falcon, the worms of the frog in ser- pents, the Ligula of fishes, the Bothriocephalus solidus of the stickleback, in the intestines of wading and swimming birds. But many other ento- zoa are met with in other parts than the intestinal canal, and beyond the reach of matters introduced from without.*
Ehrenberg endeavours to set aside the equivocal generation of the entozoa, inclining to the old opinion that the ova of these animals cir- culate with the fluids in all parts of the body. He assumes that, since the generative organs of the entozoa contain a great number of ova, these ova are carried by the circulation into all parts of the body; so that all the fluids are, as it were, infected with the ova of the entozoa, which are seated in particular organs. The milk with which other individuals of the same species are nourished, may itself contain the ova of these worms. The embryo of mammalia in which entozoa already exist, may receive the ova from the fluids of the mother. Entozoa have been found in the eggs of birds. Eschscholz found them in hen’s eggs.t It
matter of Priestley, as many persons have described. This green matter, however, is nothing more than the remains of dead infusoria, the euglena viridis. The conver- sion of this green matter into conferve, ulve, tremelle, or even mosses, is doubted by Wagner, and with justice.
* Bremser, Ueber lebenden Wiirmer im lebenden Menschen. Wien, 1819.
+ Burdach’s Physiologie, i. p. 22.
"r ENTOZOA.—~ORIGIN OF ORGANIC MATTER. 17
is possible that they may have originally found their way thither from the fluids of the mother; but, in fact, the suppositions on which the equi- vocal generation is here sought to be refuted, are as improbable as that theory itself. The ova of the entozoa are evidently too large to enter the lymphatics of the organ in which the worms live; they are much too large to circulate in capillary blood-vessels, of which the diameter is only zo!
E000 of an inch, or in fine to pass into the secretions,—the milk, or yolk of the
egg, for example : the explanation of the occurrence of entozoa in herbi- vorous animals, by transmission from mother to young, is consequently completely opposed to the known data afforded by the micrometer, un- less it be admitted, that the smallest particle of the germinal matter formed by entozoa already existing is as capable of propagating them as an entire ovum. With regard to the spermatozoa, Ehrenberg assumes that every animal receives them at the time of fecundation.
M. Von Baer * has observed many other extraordinary circumstances
in the generation of the entozoa. The animals which he names Buce-
phalus, are generated in thread-like ovistocks, which are found in mus- cles; and Bojanus and Baer have described a worm, found in the lym- næus stagnalis, which again contains numerous animals of a perfectly different form,—the cercaria. Nordmannt has seen monads in the body of living intestinal worms, namely, diplostomata; and has seen infusory ani- malcules produced in the interior of the putrefying ova of lernae. On the other hand, the changes which certain entozoa undergo deserve atten- tion; for example, the ligula and bothriocephalus solidus of fishes have no distinct genital organs until they are received into the intestines of water birds: some young distomata have at first a different form from that which they afterwards present; thus the distoma nodulosum of the perch has, according to Nordmann, at first no sucker, and is, then, pro- vided with a trace of an eye and with cilia, as if to swim in water. The infusoria and entozoa of living plants still require investigation. It is important to know, that the diseased grain of agrostis or bent-grass, phalaris or canary-grass, and wheat, contain, according to Steinbuch{ and Bauer,§ vibriones; that Bauer, having inserted vibriones into the stem of the young wheat, found them again in the ‘grain; and that the worms of the dried seeds, according to the same observers, if placed in water after several years, will again present all the phenomena of life.
Origin of organic matter and of the organic force—-In the production of infusoria tl
here is no new formation of organic matter ; the previous existence of organic beings is presupposed. Organic matter is never produced spontaneously. Plants alone seem to have the power of ge- nerating ternary or organic compounds from binary or inorganic com- pounds; while animals are nourished only by organic matter, which
* Nov. Act. Cur. x1tt. 2.
t Microgr. Beitrage. Berlin, 1832. + Analecten. 1802.
$ Philos. Trans, 1823, c
18 ORGANISM AND LIFE.
they cannot generate from binary compounds, and consequently their existence presupposes that of the vegetable kingdom. How organic beings were originally produced, and how organic matter became en- dowed with a force which is absolutely necessary to the formation and preservation of this organic matter, but which is manifested only in it, it is beyond the compass of our experience and knowledge to determine. The difficulty is not removed by saying that the organic force has re- sided in the organic matter from eternity, as if organic force and organic matter were only different ways of regarding the same object: for, in fact, the organic phenomena are presented only by a certain combina- tion of the elements ; and even organic. matter, itself susceptible of life, is reduced to inorganic compounds as soon as the cause of the vital phe- nomena, namely, the vital force, ceases to exist. This problem, however, is not a subject of experimental physiology, but of philosophy. Conviction in philosophy and in natural science has entirely different bases; the first suggestion here, therefore, is, not to be led away from the field of rational experiment. We must be content to know that the forces which give life to organic bodies are peculiar, and then examine more closely their properties.
2. Of Organism and Life.
Organised beings are composed of a number of essential and mutually dependent parts—The manner in which their elements are combined is not the only difference between organic and inorganic bodies; there is in living organic matter a principle constantly in action, the operations of which are in accordance with a rational plan, so that the individual parts, which it creates in the body, are adapted to the design of the whole ; and this it is which distinguishes organism. Kant says, “ The cause of the particular mode of existence of each part of a living body resides in the whole, while in dead masses each part contains this cause within itself.” ‘This explains why a mere part separated from an organ- ised whole generally does not continue to live; why, in fact, an organ- ised body appears to be one and indivisible. And since the different parts of an organised body are heterogeneous members of one whole, and essential to its perfect state, the trunk cannot live after the loss of one of these parts.
It is only in very simple animals or plants which possess a certain number of similar parts, or when the dissimilar parts are repeated in each successive segment of the individual, that the body can be divided, and the two portions, still possessing all the essential parts of the whole, though in smaller number, continue to live. Branches of plants separated from the trunk, being planted, form new individuals. The different parts of plants are so similar, that they are convertible one
INDIVISIBILITY OF ORGANIC BODIES. 19
into another, branches into roots, and stamens into petals.* This is the case also with some simple polypes. The experiments of Trembley, Roesel, and others, prove that portions of a divided polype will continue to grow until each half becomes a perfect animal. In the same way some worms, as the naides, in which each segment contains nearly the same essential parts,—the intestine, nerves, and blood-vessels,—have been ob- Served to propagate by spontaneous division. Bonnet states, that he has seen this new growth and reproduction in the portions of a divided earthworm ; but this animal, when thus divided, could not continue to live, for neither portion would contain all the parts Fae to the
whole. ZEA mark wh dgrrhþece iG In the higher animals, and in man, there are certain organs, —that is, parts differing in their properties and functions, —which cannot be removed without destruction of life, and of our idea of the whole; and such organs also only occur singly, as brain, spinal marrow, lungs, heart, and intestinal canal. Other parts, on the contrary, which are not mem- bers essentially necessary to our conceived idea of the whole, or which are several in number, may be removed with impunity : no part, how- ever, of one of the higher animals can continue to live when separated from the body, for no one part contains all the organs essential to the ; whole. The ovum, the germ itself, alone possesses this power ; for, at the time of its separation from the parent animal, the vital force has not formed in the germ the essential parts of the whole; and yet, when separated from the original being, it forms a new integr
is then in the organism a unity of the whole, out of dissimilar parts.
al being. There which governs its formation From the facts we have Stated, however, it appears that organised bodies are not absolutely indivisible ; they may indeed always be divided, and still retain their properties, if each portion contains the essential heterogeneous members of the whole, and in the generation even of the highest animals and plants a division takes place.
The parts of inorganic bodies are homogeneous and independent of each other.—Inorganic bodies are divisible in a much more extended sense, without the parts losing the chemical properties of the whole: they may be divided (to use the common expression) ad infinitum,—that is, ac- cording to the atomic theory, into the ultimate atoms which, on account of their minuteness, elude the senses; and in chemical compounds into molecules which are formed of the different component atoms, and which are likewise not recognisable by the senses.
There are, however, even among inorganic bodies, some which cannot be reduced by division to their ultimate particles without losing some of their properties; I mean the crystals. These bodies can be di- vided with facility only in certain directions, and the portions thus ob-
* Goethe, Metamorphose der Pflanzen. 3 c2 == =e kK brjeded pak . Abus j, fees $ kos
Acer. cleve . a Man Aa jon A Moy feo far mes =
90 ADAPTATION OF ORGANS.
tained are often different in form from the whole; for which reason some persons regard crystals also as “individuals,” which exist from the continuance of the force which formed them, and cease to exist when external, chemical (atmospheric), or mechanical influences overcome their force of crystallisation or hardness.* But even if crystals are re- garded as individuals in this sense, there is still this great distinction be- tween them and organised bodies,—that the molecules of crystals are homogeneous throughout, and that crystals are divisible, at least, into homogeneous aggregates; while organised bodies are composed of per- fectly different members of one whole, such as tissues endowed with peculiar properties. Organic combinations, moreover, never occur in a state of crystallisation in organised bodies during life. Again, in an in- organic body which is composed of heterogeneous substances aggregated together, these parts have no reference to the design and existence of the whole.
Adaptation displayed in organised bodies. — Organised bodies being composed of a certain number of dissimilar essential parts all adapted to the plan of the whole, it necessarily follows that the external and internal comformation of themselves and of their organs are such as to distinguish them entirely from inorganic bodies. That which we admire in the whole animal is not merely the manifestation of the ruling forces, as crystallisation is the consequence and manifestation of a certain force in a binary compound; but the form of the animals and of their organs evidences also an arrangement rationally adapted to the exercise of the forces, a most excellent harmony of the organisation with the faculties intended to be exercised. Crystals, on the contrary, present no adap- tation of form to an intended action of the whole, because the whole crystal is not a body composed of a number of dissimilar adapted tissues, but is produced merely by the aggregation of similar elements or for- mative particles, all subject to the same laws of crystalline attraction. Crystals, therefore, increase by the aggregation of new particles on the external surface of the parts already formed; while in the organised body the formation of the parts situated side by side, each having a different organisation, is for the most part contemporaneous ; so that the growth of organised bodies takes place in all particles of their substance at the same time, while the increase of the mass in inorganic bodies is produced by external apposition.t C tk, “(fe sh wasps bidanda
This law of organic conformation,—adaptation, to an-end, — regulates the form, not only of entire organs, but also of the simplest elementary tissues. Thus it will in a future page be shown, that the manifold
* See Mohs, Grundriss der Mineralogie, i. Vorrede, p. 6.
+ Professor E. H. Weber has made some other very interesting comparisons be- tween organisation and crystallisation in his General Anatomy. Hildebrandt’s Anat. ister Band.
€ ORGANIC SYMMETRY. 21
forms of secreting glandular structures depend simply on the various modes in which a large secreting surface can be realised in à small space. The fibrous structure of muscles is necessary to enable these organs to shorten themselves in a determined direction by the zigzag flexure of the fibres. Thus also in treating of the Physiology of the Nerves it will be shown, that unless the: nerves had been divided into a certain number of primitive fibres, which do not communicate one with another, their local action,—local circumscribed sensation,—would be impossible. The same adaptation is seen to be equally necessary in the organisation of plants. The organs of plants are less héterogeneous, and, in place of being so much enclosed in the interior, arë expanded on the surface,— the reciprocal actions with the external world being effected by the whole surface rather than by particular points; hence the general character of the conformation of plants is a surface increasing in perfect conformity with the intended purpose, this surface being presented in the manifold forms of the leaves; the individual forms in which the increase of surface is effected are more numerous than the most lively fancy can imagine, and a great part of terminology is only an attempt to form logically, a plan conformable’ to nature, of the possible varieties in the increase of surface obtained by variations of the leaves, and of their relation to pe- dicle, twig, branch, and stem.
Organic symmetry as distinguished from inorganic.—The only character that can be possibly compared in organic and inorganic bodies, is the mode in which symmetry is realised in each. Crystals have symmetrical and asymmetrical surfaces, angles and corners. Animals have also sym- metrical and asymmetrical parts, and the laws of symmetrical and asym- metrical conformation in organised bodies present similar manifold variations. The original form of the animal germ, for example, is a roundish flat disk,—the cicatricula (germinal disk, blastoderma) in the bird’s egg; this germinal disk, while in the ovary, appears, from the
researches of Purkinje and Baer, to be a vesicle. The germ is also
disk-shaped in invertebrate animals, as I have seen in the planaria. The form of the ovum and yolk must not be confounded with that of the
germ. The forms developed from the germ, however, are very various. For instance, we recognise first a radiate symmetrical type in the radiata, similar parts being arranged around a common point; the anterior and posterior surfaces of the body being the only asymmetrical parts. Secondly, we distinguish.the, symmetry of similar parts in an arborescent type, as presented by the leaves and flowers in plants, and by the polypes on the branched stem in polypiferous animals. Thirdly, we distinguish the suc- cessive symmetry in the succession of similar parts from before backwards in worms, in which the only want of symmetry is between the dorsal and ventral surfaces. Fourthly and lastly, we recognise the lateral symmetry in the repetition of similar parts on each side, in man and the higher
20 ORGANIC FORCE,
animals ; here the want of symmetry is seen in the organs taken from before backwards, and in the dissimilarity of the dorsal and ventral sur- faces. In many animals the lateral symmetry is in part combined with the successive symmetry, which is seen in the vertebre of the higher animals. In addition to the circumstance that the symmetry and asym- metry of crystallised inorganic bodies are always represented by plane surfaces and straight lines, the reverse of which is the case in organised bodies, there is also this great difference, that the symmetrical and asym- metrical parts of crystals have a simple composition, while the symme- trical parts of organised bodies are themselves in the first place formed of heterogeneous tissues. The causes which give rise to the different types of organic symmetry, just mentioned, and which first determine in the germ the position of the axis for the symmetrical developement, are as difficult to imagine as the causes of the symmetry of form in crystals.
The elementary particles of the organised body are, moreover, never crystalline ; for although some kinds of fatty matter are crystalline in the pure state, it is only when they are subjected to external influences and withdrawn from that of life. The same is the case with sugar, urea, and lithic acid. Most of the organic substances and fluids do not crys- tallise even when removed from the living body. The spinal canal and the cranial cavity of the frog have, surrounding the central parts of the nervous system, a layer of white pulpy matter which, according to Eh- renberg and Huschke, consists of microscopic crystals of carbonate of lime. In the peritoneum of fishes, and in the tapetum of the choroid of the same animals, Ehrenberg* has also discovered microscopic crys- tals of organic matter.
[Professor Schoenlein t has discovered, in the intestinal excretions, and in the yellow crusts covering the excrescences of the mucous membrane in typhus abdominalis, which are supposed to be Peyer’s follicles, a great number of small crystals, which consist chiefly of phosphate of lime, some sulphate of lime, and a salt of soda. In other kinds of fevers and of diarrhoea, and in healthy persons, the fæces contained no crystals.
Dr. Valentin has observed an imperfect crystallisation of the calca- reous matter which forms the shell of the egg of the lacerta viridis. ]
The organic force is also creative-—Hitherto I have examined merely that peculiarity of organised bodies which consists in their being systems of dissimilar organs, the existence of each of which has its source, not in itself, but in the entire system, as Kant expressed it. Zhe organic force, which resides in the whole, and on which the existence of each part depends, has however also the property of generating from organic matter the individual organs necessary to the whole. Some have believed that life,—the active phenomena of organised bodies,—is only the result of
* Miller’s Archiv. für Anat. und Physiolog. 1834, p. 158. + Ibid. 1836, p. 258. + Ibid. p. 256.
ORGANIC FORCE. 23
the harmony of the different parts—of the mutual action, as it were, of the wheels of the machine,—and that death is the consequence of a dis- turbance of this harmony. This reciprocal action of parts on each other, evidently exists; for respiration in the lungs is the cause of the acti- vity of the heart, and the motion of the heart at every moment sends blood, prepared by respiration, to the brain, which thus acquires the’ power of animating all other organs, and again gives occasion to the respiratory movements. The external impulse to the whole machinery is the atmospheric air in respiration. Any injury to one of the principal moving powers in the mechanism, every considerable lesion of the lungs, heart, or brain, may be the cause of death; hence these organs have been named the atria mortis. But the harmonious action of the essential parts of the individual subsists only by the influence of a force, the operation of which is extended to all parts of the body, and which does not depend on any single parts; this force exists before the harmonizing parts, which are, in fact, formed by it during the developement of the embryo. A complicated piece of machinery, constructed in adaptation to an end,—for example, a watch,—may present an action resulting from the co-opera- tion of individual parts, and originating in one cause: but organic beings do not merely subsist by virtue of an accidental combination of elements; the vital force inherent in them itself generates from organic matter the essential organs which constitute the whole being. This rational creative
force is exerted in every animal strictly in accordance with what the nature of each requires.
The creative force exists already in the germ, and creates in it the essen- tial parts of the future animal.—The germ is “ potentially” the whole animal; during the developement of the germ, the essential parts which constitute the “actual” whole are produced. The developement of the separate parts out of the simple mass is observable in the incubated egg, All the parts of the egg, except the germinal membrane or blastoder- ma, are destined for the nutrition of the germ; the entire vital principle of the egg resides in the germinal disk alone, and since the external influences which act on the germs of the most different organic beings are the same, we must regard the simple germinal disk, consisting of | granular amorphous matter, as the “ potential” whole of the future animal, endowed with the essential and specific force or principle of the future being, and. capable of increasing the very small amount of this specific force and matter which it already possesses, by the assimilation of new matter. The germ expands to form the germinal membrane, which grows so as to surround the yolk; and by transformation of this germ the organs of the future animal are produced, the elements merely of the nervous and vascular systems, and of the intestinal canal, being first formed, and from these elements the details of the organisation afterwards more fully de- veloped; so that the first trace of the central parts of the nervous system
sassssssiceadiessisiiimenaaessaecouniesies ee net ene ee so emes ma MAR TOA
ppe pa p bid, wt mat tuppa Wn ee Dere ape a a Re 24
ORGANIC. FORCE,
must be regarded neither as brain nor as spinal marrow, but as the still ‘ potential” whole of the central parts of the nervous system. In the same manner the different parts of the heart are seen to be developed from a uniform tube; and the first trace of the intestinal tube when there are no salivary glands and liver, is more than the mere intestinal tube; it is the “ potential” whole,—the representative of the entire digestive ap- paratus ; for, as Baer first discovered, liver, salivary glands, and pancreas are in the further progress of the vegetative process really developed from that which appears to be merely the rudiment of the intestinal canal. It can no longer be doubted that the germ is not the miniature of the future being with all its organs, as Bonnet and Haller believed, but is merely “ potentially,” this being, with the specific vital force of which it is endued, and which it becomes “ actually” by developement, and by the production of the organs essential to the active state of the “actual” being. For the germ itself is formed merely of amorphous matter, and a high magnifying power is not necessary to distinguish the first rudiments of the separate organs, which from their first appearance are distinct and pretty large, but simple; so that the later complicated state of a particular organ can be seen to arise by transformation from its simple rudiment. These remarks are now no longer mere opinions, but facts; and nothing is more distinct than the developement of glands from the intestinal tube, and of the intestinal tube itself from a portion of the germinal membrane. i The creative organic force is not, like the mind, connected with one special organ—If Ernst Stahl had been acquainted with the above facts, he would have been still more confirmed in his famous theory, that the rational soul itself is the primum movens of organisation; that it is the ultimate and sole cause of organic activity ; that the soul constructs con- formably to design, and preserves its body in accordance with the laws of its operation; and that by its organic action the cure of diseases is effected. Stahl’s contemporaries and followers have partly misunderstood this great man, in believing that, according to his view, the soul, which forms mental conceptions, also conducts with consciousness, and design- edly, the organisation of the body. The soul (anima) spoken of by Stahl is the organising power or principle which manifests itselfin conformity with a rational law. But Stahl has gone too far in placing the manifestations of soul, combined with consciousness, on a level with the organising principle; the operations of which, though in accordance with design, obey a blind necessity. J The organising principle, which according to an eter W creates the different essential organs of the body, and animates them, is not itself seated in one particular organ; it continues in opera- tion up to the time of birth in_anencephalous monsters; it modifies the already existing nervous sjale iaeiiai a organs in the larvæ of insects, during their transformation, causing the disappearance of several of the ganglia of the nervous cord, and the union of others;
Ne
x ORIGIN OF GENERA AND SPECIES. 25
by its operation during the transformation of the tadpole to the frog, the Spinal marrow is shortened in proportion as the tail becomes atrophied, and the nerves of the extremities are formed. This principle, thus acting conformably to design, but without consciousness, is also manifested in the phenomena of instinct. There is great beauty and truth in the saying of Cuvier, that animals acting from instinct are, as it were, possessed by an innate idea, by a dream. But that which excites this dream can be nothing else than the oiesieing principle, the “ final cause” of the being. D cm fantem a9
The existence of the organic principle in the germ, and its apparent independence of any special organ in the adult, as well as the fact that it is manifested in plants, in which both nervous system and consciousness are wanting, prove that this principle cannot be compared with mental consciousness, which is an after product of developement, and has its seat in one particular organ. Mind can generate no organic products, it can merely form conceptions; our ideas of the organised being aré mere Conscious conceptions of the mind. The formative or organising princi- ple, on the contrary, is a creative power modifying matter, blindly and unconsciously, according to the laws of adaptation.
Origin of genera and species.—Organism, or the organised state, is the result of the union of the organic creative power and organic matter. Whether. the two have ever been separate, whether the creative arche- types, the eternal ideas of Plato, as he taught in his “ Timzeus,” have at some former period been infused into matter, and from that time for- ward are perpetuated in each animal and plant, is not an object of science, but of the fables and traditions which cannot be proved, and which distinctly indicate to us the limits of our mere consciousness. All that is known is, that each form of animal or plant is continued un- changed in its products, and that, in a roughly calculated number of many thousand species of animals and plants, there are no true trans- itions of one species to another, or of one genus to another; family of plants and animals, each genus, and each species,
with certain physical conditions of its existence, perature,
it is, as it
each is connected with a certain tem- and with determinate physico-geographical relations, for which were, created. In this endless variety of creatures, in this re- gularity of the natural classes, families, one common creative principle,
world depends.
genera, and species, is manifested on which life generally throughout the But all these varieties of organism, all these animals, which are as it were so many modes in which the surrounding world may be enjoyed by means of sensation and reaction, are, from the mo- ment of their creation, independent. The species perishes when the pro- ductive individuals are all destroyed; the genus is no longer capable of generating the species, nor the family of restoring the genus. In the Course of the earth’s history, species of animals have perished by the
26 ORGANIC FORCE.
revolutions of its surface, and have been buried in the ruins; these belong partly to extinct genera, partly to genera still existing.
The study of the successive strata of the earth, in which the remains of organic beings occur, seems to prove that the beings, which have thus left their remains on the earth, have not all existed at the same time, that the simplest creatures have first inhabited the earth; while the remains of the higher animals, and particularly those of man, are not met with except in the most superficial of the deposits which
| contain organic remains. But no fact justifies us in speculations con-
cerning the original, or subsequent origin of living beings; no fact
/ indicates the possibility of explaining all these varieties by transformation,
| for all creatures maintain unchanged the forms which they originally re- | ceived,
Nature of the organic force.—The unity resulting from the combination of the organising force with organic matter could be better conceived, if it could be proved that the organising force and the phenomena of life are the result, manifestation, or property of a certain combination of elements. The difference of animate and inanimate organic matter would then consist, in that state of combination of the elements, which is neces- sary to life, having in the latter undergone some change. Reil has stated this bold theory in his famous treatise on the “ vital energy,”* which some physiologists, —Rudolphi, for example, —regard as a masterpiece, on which the principles of physiology must be founded.
Reil refers the organic phenomena to original difference in the ele- mentary combination and form of the organic bodies. Differences in the mode of combination of the elements and in form, are, according to his theory, the cause of all the variety in organised bodies, and in their endowments. But if these two principles be admitted, still the problem remains unsolved; it may still be asked, how the elementary combina- tion acquired its form, and how the form acquired its elementary com- bination. That the form of the organic matter does not determine originally the mode of its action, is proved indisputably by the fact, that the matter from which all animal forms are produced is at first almost without form. The germ in all vertebrata, and probably also in the invertebrata, from what is known of a few species, and from what I have observed in the planaria, is a round disk of simple matter; here is no diference of form corresponding to the difference of the animals. On the other hand, the form of inorganic bodies is always determined by their elements, or by the combination of their elements. And this Reil himself admits ; for he says: “ Form of matter is itself a phenomenon, which depends on another phenomenon, namely, the elective affinity of the elements and their products.” Hence it would follow, that if the elementary combination were alone the cause of the organic forces, this
* Reil’s Archiv. fur Physiologie, i. Bd.
ITS NATURE. 27
elementary combination itself would be at the same time the formative principle. Now, since in organised bodies immediately after death the elementary combination does not appear to be different from that of bodies still living, Reil must admit the existence of other more sub- tile matters not recognisable by chemical analysis, which are present in the living body, but are wanting after death. Into the composition of the organic matter of the living body there must enter an unknown (according to Reil’s theory, subtile material) principle, or the organic matter must maintain its properties by the operation of some unknown forces. Whether this principle is to be regarded as an imponderable matter, or as a force or energy, is just as uncertain as the same ques- tion is in reference to several important phenomena in physics ; phy- siology in this case is not behind the other natural sciences, for the properties of this principle in the functions of the nerves are nearly as well known as those of light, caloric, and electricity, in physics.
At all events, the mobility of this principle is certain. Its motion is evident in innumerable vital phenomena. Parts frozen, stiff, and deprived of sensation and motion, are observed gradually to recover animation, which extends into them from the borders of the living parts. This passage of the vital principle from one part to another, is seen still more clearly on the removal of pressure from a nerve, after that state has been produced in which the limb is said to be « asleep.” The fibrin effused in inflammation on the surface of an organ, is observed to be- come endowed with life and organisation, This organic principle exerts its influence even beyond the surface of an organ, as is shown by the changes produced in the animal matter contained in the vessels, for instance, in the lymph and chyle, which latter fluid during its progress through the lacteals acquires new properties; from the coats of the blood-vessels, again, the organic principle exerts an influence on thé blood, maintaining
its fluidity, for out of the vessels the blood coagulates under almost all circumstances,
I may with Au of which vital again imparted to them, I do not think that it i an unincubated egg pres Hunter remarks; but it bidly collected fluid, e from putrefaction lon
unless it has undergone some chemical change. Lastly, tenrieth adduce that property of animal tissues, energy is at one time withdrawn from them, and then
by virtue
and is often quickly accumulated in one organ. s the influence of the vital energy which in erves the yolk and white from putrefaction, as is certain that an extravasated, enclosed, or mor- ven morbid animal matter, as pus, is preserved
ger in the living body than out of it; which does not arise merely from the exclusion of air, since, when the vital
powers are low, blood and pus rapidly undergo decomposition even in the body.* From all these facts the existence of a force which is often rapid in its action, and which moves through space, or of an imponderable
* Autenrieth, Physiologie, i.
28 EXTERNAL CONDITIONS NECESSARY FOR LIFE.
matter, is evident; nevertheless we are by no means justified in regard- ing it as identical with the known imponderable matters, or general physical forces,—caloric, light, and electricity, a comparison which is refuted by any close examination. The researches on the so-called animal magnetism at. first promised to throw some light on this enig- matical principle, or imponderable matter. It was thought that, by one person laying his hand upon, or passing it along the surface of another, and by other procedures, remarkable effects were produced, arising from the overflow of the animal magnetic fluid; some indeed have imagined that by certain operations they could produce accumulation of this hypothetic fluid. These tales, however, are a lamentable tissue of false- hood, deception, and credulity; and from them we have only learned how incapable most medical men are of instituting an experimental in- vestigation, how little idea they have of a logical criticism, which in other natural sciences has become a universal method. There is no single fact relating to this doctrine which is free from doubt, except the cer- tainty of endless deceptions; and in the practice of medicine there is also no fact which can be connected with these wonders, except the often repeated, but still unconfirmed accounts of the cure of para- lysis by investing the limbs with the bodies of animals just killed, and the willingly credited fables of the restoral of youth to the old and diseased by their being in the proximity and exposed to the exhalation of healthy children, and vice versa.
We have thus seen that organic bodies consist of matters which pre- sent a peculiar combination of their component elements, a combination of three, four, or more to form one compound, which is observed only in organic bodies, and in them only during life. Organised bodies more- over are constituted of organs,—that is, of essential members of one whole,—each member having a separate function, and each deriving its existence from the whole; and they not merely consist of these organs, but by virtue of an innate power they form them within themselves. “Life, therefore, is not simply the result of the harmony and reciprocal action of these parts ; but is first manifested in a principle or impondera- ble matter which is in action in the substance of the germ, enters into the composition of the matter of this germ, and imparts to organic com- binations properties which cease at death.
Conditions necessary for the manifestation of life.— Vital stimuli.—The action of the vital or organic force is, however, not independent of cer- tain conditions. The necessary elementary combination and the vital principle itself may be present, and yet not manifest themselves by the phenomena of life. This quiescent state of the vital principle, as it is seen in the impregnated germ of the egg before incubation, or in the seed of plants before germination, must not be confounded with the state of
(LA eo rnga ae 4 g ken prha d &
VITAL STIMULI, 29
death; it is also not life, but a specific state of “ capability of living.” Life itself, namely, the manifestation of the organic or vital force, begins under the influence of certain necessary conditions: these are warmth, atmospheric air, (in ova which are hatched in water, the air diffused through the water), and the supply of moist nutritive matters,—that is to say, of nutriment and water; and these conditions do not cease to be necessary for the continued manifestation of life.
The ovum of animals and plants remains in the state of germ only so long as it is maintained perfectly quiescent and beyond the influence of external agencies: it then remains capable of developement, and retains the creative force of the germ, but this force is in a quiescent state. The ova of animals will retain for a long period their capability of develope- ment, while withdrawn from the influence of the atmosphere. Thus the productive power of the germ of the ova of many insects is preserved through the winter, and the ova of insects of transatlantic countries are hatched in the botanic gardens of Europe, an instance of which has fallen under my observation. In the same way the germinating power of the seeds of many phanerogamic plants is said to be preserved under water for twenty years, and in the ground beyond the influence of the atmo- spheric air for one hundred years.* Treviranus adduces the observations of Van Swieten that the seeds of the mimosa have germinated at the end of twenty years, and beans after two hundred years; and cites another observation, according to which an onion taken from the hand of an Egyptian mummy, perhaps two thousand years old, had been made to
grow.t As soon, however, as it is subjected to the external influences
above mentioned, the germ, when capable of developement, becomes
developed, or it undergoes putrefaction ; while the already developed or- ganism, when the conditions necessary for its further growth fail, either falls into a state of apparent death, as in hybernation, or it dies. The quiescent vital force of the germ required no external stimuli for the maintenance of its passive existence; but these stimuli are very neces- sary for the developed and active life.
Action of the vital stimuli—The external conditions which are neces- sary to life,—caloric, water, atmospheric air, and nutriment, at the same time that they maintain life, induce constant changes in the composition of the organised body; themselves combining with the body, while certain old components are again decomposed and cast off. These external agencies have been called vital stimuli; they must, however, be carefully distinguished from many other accidental stimuli
which are not essential to life; and it must always be remember-
ed, that these vital stimuli produce the phenomena of life by effecting
* Ann. d. Sc. Nat. t. v. 380. + Treviranus, Erschein. i Gesetz des Organ. Lebens, p. 47.
30 ACTION OF VITAL STIMULI.
material changes, by producing an interchange of ponderable and im- ponderable matters. The essential elementary combination of the fluids, for example the blood, is by their agency constantly maintained, and the blood having suffered the necessary change by the action of the vital sti- muli, in its turn stimulates all the organs of the body,—that is, produces in them organic changes of composition, essential to the manifestation of life, by the interchange of ponderable and imponderable matters, the old components of the organs being at the same time in part decom- posed and cast off. In animals the nerves also effect important material changes in the organs ; and their active force, probably an impondera- ble agent, is an important internal vital stimulus. The property of or- ganised bodies of suffering constantly, by the action of the vital stimuli, certain material modifications necessary to the manifestation of life, has been termed incitabilitas, excitability (Reitzbarkeit). The stimuli are as it were the external force which sets in motion the wheels of the whole machine ; and although the comparison of the animal body with a machine may not be very apt, yet the organic principle which in the organised body creates the mechanism necessary to life, is incapable of activity without this external impulse, and without the constant mate- rial changes effected by the aid of the external vital stimuli. Riche- rand has, therefore, not unaptly compared the manifestation of life with the phenomenon of combustion and flame. The appearance of fire en- dures only as long as the combinations and decompositions essential to combustion take place; the oxygen unites with the burning body, caloric is developed, and so long as oxygen and the combustible mat- 8" are supplied, the phenomena of fire continue. I am very far from | making life dependent on combustion; I merely say, that, in both, cer- Í tain essential combinations and decompositions are constantly going on, which in the one produce the phenomena of combustion and light, in < the other those of life ; that the vital stimuli are for the organised body, ! what the oxygen of the atmosphere and the combustible matter are for the phenomena of combustion ; in which case, however, the oxygen is ' not called the stimulus of the flame: and I further say, that the name stimulus, vital stimulus, gives an empty and indeed false notion, un- less the material changes,—the constant new combinations and decom- position of ponderable and imponderable matters—induced by it be at the same time remembered. It is, however, necessary always to recollect, that in the material changes effected by the vital stimuli, although inorganic substances come into play in them, binary com- pounds are not generated for the organism, but only cast off as the result of the decomposition of the old matter ; such a product is carbonic acid: while the oxygen, which in the process of respiration partly enters into combination witly the blood, produces a certain change in this fluid, which in its turn must produce in the organs endowed with the
y% = T yell ro cople = jus al ree cee few E å, U T vO, eh Ye yt Gay `
NECESSITY OF VITAL STIMULI. 3l
vital principle, material changes very different from those that would be expected in a dead body.
These general essentials of life, the vital stimuli, or renovating (inte- grirende) stimuli, are common to plants and animals: for plants, light is also an indispensable vivifying stimulus; for animals, although the want of its influence renders the body scrofulous and rickety, it is not immediately necessary, as is proved by the life of many animals, particu- larly the entozoa, and its absence is only so far injurious as it modifies the other essential vital stimuli. As an essential for animal life must be reckoned not merely the assumption of new matter, matter already organised; while plants take up as nutriment organised matters partly converted into binary compounds, and change these binary into ternary compounds. The necessity of new matter, caloric, water, and atmospheric air for the developement, subsistence, and growth of organised bodies, is quite indispensable.
A great error has been committed in classing the vivifying stimuli with other stimuli, which do not essentially enter into the composition of orga- nic bodies, and do not renovate their powers. A mechanical stimulus, which modifies the condition of a membrane endowed with sensibility,— for example, pressure,—excites, it is true, a vital phenomenon—sensation, but does not vivify, does not invigorate the organic forces; while, on the contrary, the essential vital stimuli really contribute to the formation of is not merely a sti- body ; it is itself susceptible of life, it is a stimulus in the healthy state, can a week without fatal con- ny weeks without it; rep- have been known to fast for months,—this has been chiefly observed in Serpents and tortoises. Water, whether it enters as such into the composition of the organic matters, or contributes its elements to their composition, is also absolutely essential in its un- combined state to the manifestation of life, since the animal tissues, un- less they are moist with water, are incapable of living. Atmospheric air
is so essential for the manifestation of the vital phenomena, that in the
higher animals life does not subsist a moment without respiration, with-
out the changes in the blood effected by respiration, and without the influence of blood so changed upon the organs. The supply of nutriment, and the assumption of new matter from the blood into the organs, may be suspended for a considerable time, particularly in reptiles; but this other change, which the blood effects in the organs by virtue of its aera- tion in the lungs, can be suspended in reptiles but for a short time, in
Man only for a few seconds. Caloric, lastly, which is
s especially important at the time when the animal system is itself yet unable to generate any
heat, but is indispensable for all organic beings, plants and animals, seems
but more especially of
the organic matter. The nutriment, in the first place, mulus of the organic which vivifies, and can itself be vivified. Man, scarcely dispense with food for longer than Sequences ; the higher brutes do not live ma tiles, on the contrary,
82 VITAL STIMULI.
also to enter into the composition of the organic system. For the organic processes require in every animal and plant a certain temperature ; and it is also known, that in chemical processes among binary compounds, while a certain temperature is required, a determinate quantity of caloric be- comes latent, or is absorbed for the formation of new compounds. Under the influence of the vital stimuli,—nutriment, water, air and caloric,—the organic being is developed spontaneously from the germ, while the organic matter present in it is constantly undergoing decomposition, and the phe- nomena of life are themselves the results of the constant union of new and the separation of old elements of the organised matter. Whether electricity also is necessary to the developement of life is at present quite uncertain.
There is, however, an evident difference in the degree in which living beings are dependent on different vital stimuli. M. Edwards has observed, that newly-born warm-blooded animals have most need of external ~ warmth, and without it cannot live; while they can live under water, without breathing, much longer than adult animals. The time that they can remain in the water is longer in proportion as the temperature of
the water rises from 32° to 68° Fahr.; remains the same when the water is between 68° and 86° Fahr.; and becomes shorter between 86° and 104° Fahr.* The adult animal has, according to the vital relations of its species and genus, a certain temperature, and consequently a certain
geographical tract, assigned to it in which to live.
The duration of irritability without the application of the vital stimuli, is generally in the inverse ratio of the perfection of the organisation. The simplest animals can longest dispense with these stimuli. Mol- lusca and insects, as well as the scorpion, have been kept for months without food t Serpents and tortoises also live for months without food, while man in the healthy state can scarcely survive a week. Several insects will live for days in mephitic gases; the larvee of the estrus, for example, according to the experiments of Van der Kolk, live for a long period in irrespirable gases. Molluscous animals have been kept during 24 hours under the air-pump. Reptiles live a very long time without respiring ; in water deprived of its air some few hours, according to Spal- anzani and Edwards, and in water still containing air, from 10 to 20 hours: frogs, the lungs of which I had extirpated, lived 30 hours. The numerous accounts, however, of toads, &c. having been found living in blocks of marble, and in trees, are to be regarded as instances of decep- tion and credulity, although Herissaut and Edwards kept reptiles alive for some little time enclosed in gypsum. But Edwards is convinced that gypsum is permeable to atmospheric air; when the reptiles were _* Edwards, De l'influence des agens physiques sur la vie. Froriep’s Notiz. 150, 151. See also Legallois, Exper. sur le principe de la vie.
+ See my paper on the Scorpion, in Meckel’s Archiv. 1828.
DEATH OF ORGANISED BODIES, 33
surrounded both by gypsum and mercury, they died as quickly as if under water.* The greater complication of the organisation increases the state of dependence of the organs on each other. Simple ani- mals therefore live longer after injuries, than animals higher in the scale. Revival from the state of apparent death is much more easy in the lower animals, Spallanzani and F ontana saw wheel-animalcules, which had suf. fered desiccation, recover the appearance of life on being moistened with water. Ehrenberg, however, denies that this could occur. Steinbuch and Bauer have observed the same fact with regard to the vibriones of dis- eased wheat and of an agrostis ; they revived when the grain was moisten- ed, after an interval of years. After the most severe injuries, reptiles
me ; and the long persistance of irritability in the muscles and nerves of these animals is well known. The signs of life continue for a longer period in young animals also, probably on ac- count of the greater simplicity of their structure. In the embryos of rabbits, I have seen the muscular irritability continue longer after death than in adult rabbits ; and a foetal rabbit removed from the uterus retained its life for fifteen minutes under the air-pump. On this point, Legallois has made some interesting experiments, the result of which is, that on kill- ing rabbits by immersion in water, excision of the heart, or opening the thorax, on the first, fifth, tenth, and so on every fifth day until the thirtieth day after birth, it is found that the duration of sensibility is less every fifth day; so that, while on the first day it continued fifteen minutes, on the thirtieth day it endured only two and a half minutes. Legallois observed the same relation with regard to the persistance of the circu- lation after the spinal cord was destroyed, and the head cut off. All) these facts are fully explained by the law, that the more developed the | individual parts of a whole are, the more dependent they must be one | upon the other.
Organised bodies are subject to death.—While life is continued, with an’ appearance of immortality, from one individual to another, the individuals themselves perish; but if adi the individuals of a Species are destroyed, the species itself, whether of animals or plants, becomes extinct, as the history of the earth proves. The vital or organie Jorce flows, as it were, in a stream from the producing parts into those ever newly produced, while the old parts perish. This is well described by Autenrieth:?
“ Those organised bodies only,” he says, “ which constantly strike fresh —
roots,—as the creeping plants, for example, by means of runners; or, as |
many trees, by means of descending branches, — do not die. Tn all these cases the new Sprout forms, at one period, a part of the old individual, at the same time that it is a new and independent being. But even in these plants the old stem always perishes, and the vital force
* Edwards, in Meckel’s Archiv. iii. p. 617.
34 ORGANISED BODIES.—DEATH.
continues active only in the new offset, which in its turn continues to extend itself on the one side, while it dies on the other. What here takes place connectedly,—namely, the decay on the one side, and the for- mation of a new living body on the other,—is effected in an interrupted manner in man and the more perfect animals. The young is separated from the parent as a new living body, before the old being perishes; and the original individual dies, while the species seems to be im- mortal.” *
Cause of death.—Why organised bodies perish, and why the organic force is transferred from the producing parts of organic beings to the young living products, while the old producing parts perish, is one of the most difficult problems of general physiology. We cannot solve it, but can only describe the phenomena in their connection. It would not be sufficient to say that inorganic influences gradually destroy life ; for in that case the vital force would begin to diminish from the very com- mencement of existence ; and it is well known that at the time of virility the vital force is in such a state of perfection that it multiplies itself by the formation of germs. There must then be some other more occult cause, which induces the death of the individuals, while it ensures the propagation of the vital force from one individual to another, and in this way secures it from perishing. It might be asserted that the in- creasing fragility of organic bodies in old age arises from the increasing accumulation in them of certain products of the decomposition of the organic substance, the chemical affinity of which matters at last balances the vital or organic force; but in that case, also, the vital force must diminish from the very commencement of life; and there is besides no proof of such accumulation taking place. All that can be done, therefore, is to show the connection of these phenomena with developement. If the germ of an organic being is compared with its state in extreme age, it is seen that, at the latter period, the whole, on which, according to Kant, the existence of the individual parts depends, subsists almost solely by the reciprocal action of the individual parts and of their forces, like the working of a piece of machinery, which is maintained solely by the reci- procal action of the parts of the machine on each other ; in the germ, on the contrary, the force, in which is seated the producing cause of all the parts of the future body, is still undivided. The organic principle in the germ is, as it were, in the state of the greatest concentration. The capabi- lity of developement is at its highest degree, developement itself at its lowest. When the operation of this principle has endured for a certain time, when the period of youth is passed, this state of simplicity, in which the whole force is undivided, no longer exists; there is then a state of complication, in which the force is divided among the different parts.
* Autenrieth, Physiol. i. 112.
=>
€ CHANGE OF MATERIAL. 35
But the more the single organic force of the body becomes divided, and the less of this force remains unapplied, so much the more does the organism seem to lose the property of becoming vivified by the influence of the general vital stimuli ; and the less strong becomes, as it were, the affinity between the organised substance and the stimuli, which seem to nourish the flame of life. Therefore, when developement is complete, if the immortality of the vital force is to be secured, the formation of a germ is necessary. The germ, containing the vital principle in an un- divided state, also possesses the greatest affinity for the vital stimuli, and this affinity again diminishes in proportion as the organism is deve- loped. This has the appearance of explaining the pħenomena, but is in reality merely a statement of their connection, and it is not even certain that the statement is correct.
Why organic matter perishes—The cause of the constant destruction of the matter of organic bodies during life, and of the necessity for its being replaced by new organic matter, is the second point to be investi- gated. In plants this change of material is less remarkable, and is seen, to a great extent at least, only in the gradual death of the old leaves: in plants, as Tiedemann remarks, what is once formed, is for a long time subject to no change of material, but retains, for a certain period, its first composition. In animals, on the contrary, there is a constant renewal of the component matter. This difference between animals and plants, Tiedemann explains, by supposing that in animals there are certain functions, the performance of which induce changes in the material composition of the organs, as seems to be the case in the action of the nerves.*
M. Sniadecki’s theory—M. Sniadecki, who has endeavoured to solve this problem,t calls the substances which are capable of nourishing or- ganised bodies, matters susceptible of animation. The susceptibility of animation with which these matters are endowed, is however quite general ; they are capable of taking any form as long as they are not Subjected to special influences, and for that reason are without special form. Organic matter then has, as M. Sniadecki expresses it, a general tendency to life and organisation. But as soon as any part of it comes within the influence of any individual being, the vital force of the indi- vidual gives a special direction to this general tendency; hence the in- dividual and local conformation, and the different modes of life. Every special form of organisation is thus, according to M. Sniadecki, the result of two tendencies ; one general, which resides in the matter itself, and by virtue of which certain substances strive towards life and organisation generally; and a second special tendency, which exists in the individual, and this latter determines the mode in which the life shall be manifested,
* Physiol. i. p. 376, + Theorie der organischen Wesen, aus dem Polnischen. Nürnberg, 1821,
Dee,
36 ORGANISED BODIES.
and the form in which the organisation shall be effected. This particle of vivifiable matter, therefore, which has been subjected wholly or in part to the influence of the vital principle of a certain individual, has acquired a proportional degree of vitality ; but, as it has not ceased to be susceptible of life, it must, in virtue of this susceptibility, still tend towards further life, and to the assumption of all the other forms of organisation, —that which it already possesses being alone excepted. If this particle of matter is now compared with the organic matter, which is as yet quite unorganised, and which has an equal tendency to assume all forms, it is evident that it must possess less susceptibility of life than the latter. The diminution of its susceptibility of animation must be commensurate with the tendency which it had to take the particular form in which it exists, this tendency being already satisfied.
From this reasoning M. Sniadecki concludes, that the capacity of the matter in organised individuals for life, is in the inverse ratio of the vital force to which it has already been subjected ; or, in other words, the matter which is taken into organised bodies loses just as much of its capacity for life as it gains of individual power; consequently, in the same proportion as it assumes a given form, it loses its faculty of assum- ing that form. As soon, then, as it is completely organised, and has undergone the whole vivifying power of the individual, it loses all suscep- tibility of organisation in reference to this individual. The vital force of the individual then loses all power over it; and this matter will, in the midst of the living body, be incapable of living and inert, and con- sequently only fit to be discharged from the body. In this way Snia- decki explains the constant change of organisable matters in organised bodies.
If this explanation is adopted, the general processes in organised bodies can certainly be further explained, as has been done by M. Snia- decki with admirable simplicity and clearness. Strong objections, how- ever, may be urged against it. According to M. Sniadecki’s doctrine, the only essential part of organised bodies is, not the organised matter, but the organic force. The force manifests itself as long as its organising action is continued ; that is, as long as matter susceptible of organisa- tion is present: the organised matter itself possesses no organic force, and is excreted from the body as being useless. But, according to this view, the excrementitious matters ought to bear the character of com- plete organisation, and should be susceptible of immediate organisation by other beings. ‘This is not the case. The excrementitious matters of most general occurrence are the urine, and the carbonic acid which is exhaled in respiration. But these substances are not susceptible of organisation by other animals; they are the products of the decomposi- tion of animal matters.
Author's views.—It is much more consonant with facts to suppose that
CHANGE OF MATERIAL.—EXCRETIONS. 37
the matter assimilated by an organised body becomes endowed with the organising power at the moment that it is organised. The organising force itself is in many simple organic beings divisible, by division of the organised matter. We are thus led to the very opposite conclusion to that of M. Sniadecki. He maintains that the matter loses its capacity for life in proportion as it is endowed with life. We say, matter becomes vivi- fied in proportion as it has experienced the vivifying force ; it acquires the power of imparting life to other matter in proportion as it is itself vivified ; and it exercises this power while acted on by certain vital stimuli, which, while they unite with the organised tissues, cause the separation and excretion of other substances. Certain vital stimuli entering the blood, as in the process of respiration, and then exerting their influence on the organised tissues, cause the affinity between certain elements of the organised matter and the blood to become greater than that between the different elements of the organised matter itself. The vivification of the organised matter by the vital stimuli, in a manner which is attended with excretion, renders it capable of receiving nutriment ; but, in proportion as a portion of matter has life imparted to it, it acquires the faculty of giving life and organisation to other matters: it does not become excrementitious ; on the contrary, it participates in the organis- ing force of the original body.
The cause why organic substances are being constantly decomposed and cast off from the animal body, might at first sight be thought to lie in the following circumstance :—In the conversion of the food into matters proper for the nutrition of the body, some substances, from containing an excess of useless elements, may be necessarily ejected again. Thus plants, in forming ternary vegetable compounds from car- bonic acid and water, give out the superfluous oxygen. In animals the only excrementitious matters of any consequence, which are quite useless in the organic system, are the carbonic acid and the urine. The excretions of animals, it is true, nearly equal in quantity the matter taken into the body; but in part they are purely useless excreta : many are destined for particular purposes, or are evacuated acciden- tally, as the mucus of the intestines, and perhaps also the bile. - The fæces consist partly of substances taken as food; whereas the urine and carbonic acid are separated from organised tissues, and are per- fectly useless to the system. The urine certainly varies in its compo- sition according to the nature of the food, and therefore evidently con- tains also useless components of the yet unorganised food. But the Composition of the urine remains unaltered in animals which live without food even for months, as many rèptiles, serpents, and tortoises will do. The urine, therefore, it is certain, must be a means of carrying out of the
System parts of the organised components which have become useless; and it is evident that the vital actions themselves are attended with decomposi-
88 ORGANISED BODIES.
tion of organic matter. Thus even the pup of insects at the period of their transformation, when they take no nourishment, afford excremen- titious matter by means of the Malpighian vessels ; and Wurzer, Brugna- telli, and M. Chevreul have shown us that these vessels secrete lithic acid. The embryo of the higher animals, also, forms a peculiar excretion by means of the Wolffian bodies, even before the kidneys have assumed their function.
It is remarkable, also, that urea and lithic acid are excreted by many invertebrate animals as well as by the vertebrate; thus insects, as we have said, secrete lithic acid by the Malpighian vessels, and M. Jacob- son has discovered lithic acid in a special excretory organ in molluscous animals. We have not the most distant conception of the cause which renders the reciprocal action of the atmospheric air with the living body so necessary to life ; but the hypothesis that respiration supplies the ele- ments still required for the formation of animal matter, or removes the elements superfluous to this compound, is refuted by the facts that most animals take the animal matter ready formed, and that reptiles continue to respire, to consume the oxygen of the air, and to exhale carbonic acid, when they take no food for months.
The excretions which are being constantly formed by the vital process even without food being taken, namely, carbonic acid and urea, (and lithic acid,) are incapable of nourishing other animals. Carbonic acid is a binary compound formed by the decomposition of animal matter: urea is very analogous to a binary compound, and is perhaps really one; at
all events, Woehler has shown that it is produced from cyanite of ammonia with extreme ease.
As these excretions are constant, even when the supply of nutriment is stopped, it necessarily follows that a constant decomposition of the substance of the body is essentially con-
nected with life. It cannot indeed be otherwise, if it be true, as it has already been proved to be, that the vital force is manifested in an animal only while certain vital stimuli produce in the living tissues constant -material changes, of which the phenomena of life are merely the exter- nal signs, just as flame is the appearance resulting from the material changes effected in combustion. The impulse to these material changes is given by respiration; the blood, undergoing a constant change by respiratory process, again effects constant material changes in the organs to which it is distributed: from the former components of the tissues are formed the general products of decomposition,—carbonic acid, and the substances so rich in nitrogen which are found in the urine, urea and lithic acid;—and this decomposition of the materials of the body, which constantly attends the vital process, in its turn renders necessary the supply of new nutritive matters, which are subjected to the organising force. An organised part presents vital phenomena, and organises new matter, only while excited by the constant exertion of organic affinity
SOURCES OF NEW MATERIAL AND VITAL FORCE. 39
between the blood and the components of the tissues ; by the exertion of which affinity certain components of the organs are decomposed, their place being again supplied by new nutritive matter acted on by the or- ganic force.
Sources of new organised matter.—The nutriment of animals consists of organic matters, animal and vegetable ; the nutriment of plants consists partly of vegetable and animal matters not wholly decomposed, and partly of binary compounds, namely, carbonic acid and water. It has been imagined that plants can nourish themselves from carbonic acid and water alone; the experiments of Hassenfratz, M. de Saussure, Giobert, and Link, have proved however that plants under these circumstances, if they grow at all, do so very imperfectly, and seldom flower and bear fruit.* It appears, therefore, that it is only when they are at the same time nourished by organic compounds in solution, which have not wholly ‘undergone decomposition, that plants generate organic matter from binary compounds.
The power of generating organic from mineral compounds cannot, however, be entirely denied to plants; for, were it not for this power, the vegetable and animal kingdoms would soon perish. The unceas- ing destruction of organic bodies presupposes the formation by plants of new organic matter from binary compounds and elementary sub- stances.
The organic force also is increased during the organisation of new matter. —Now, by the growth and propagation of organised bodies, the organic force seems to be multiplied ; for from one being many others are pro- duced, and from these in their turn many more ; while, on the other hand, with the death of organised bodies the organic force also seems to perish. But the organic force is not merely transmitted, as it were, from one individual to another,—on the contrary, a plant, after producing yearly the germs of very many productive individuals, may still remain capable of the same production,—the source of the increase of the organic or vital force seems therefore also to lie in the organisation of new matter ; and, this being admitted, it must be allowed that plants, while they form new organic matter from inorganic substances under the influence of light and caloric, are also endowed with the power of increasing the organic force from unknown external sources, while animals also in their turn would generate the organic force from their nutriment under the influence of the vital Stimuli, and distribute it to the germs during propa- gation. Whether during life the organic force, as well as the organic matter, is constantly suffering destruction, is quite unknown. Thus much however seems certain, that, at the death of organic bodies, the vital force is resolved into its general natural causes, from which it appears to be generated anew by plants. If this increase of the vital principle
* Tiedemann’s Physiolog. i. 218, Translation, p, 83.
40 DIFFERENCES OF PLANTS AND ANIMALS.
in existing organised bodies from unknown sources in the external world be not admitted, it must be supposed that the apparently endless mul- tiplication of the vital force in the process of growth and in propagation is merely an evolution of germs encased one within another, or it must be admitted that the division of the organic force which takes place in propagation does not weaken its intensity ; a supposition which appears absurd. But the fact would still remain, that, by the death of organised
bodies, organic force is constantly becoming inert, or resolved into its general physical causes.
8. Of the Organism and Life of Animals.
Differences of plants and animals.— Developement, growth, excita- bility, propagation, and decay, are the general phenomena and pro- perties of all organised bodies, and are the results of organisation ; but there are other properties peculiar to animals, which may therefore be termed animal in contradistinction to the general’ organic proper- ties. Sensation and voluntary motion are the more remarkable animal properties.
Motions of plants. — Plants, it is true, are not wholly without motion, for their organisation is attended with internal motions, namely, the cir- culation of the sap; moreover, they turn spontaneously towards the light, their roots extend in the direction of the most nutritious soil: some plants climb along the surface of bodies which offer them means of attachment, and their stamens incline towards the pistil at the time of impregnation; many plants indeed, particularly those of the genus mimosa, possess in their leafstalks a power of motion which can be ex- cited by various irritants, whether mechanical, galvanic, or chemical— such as alcohol, mineral acids, æther, and ammonia,—as well as by change of temperature or light; thus affording another instance of the general law, that the specific excitable properties of organic bodies do not vary in the mode of their manifestation according to the nature of the stimulus which excites them, but are manifested each in its peculiar manner on the application of the most different stimuli.* Lastly, in the hedysa- rum gyrans there is, besides the general influence of light on the motion of the larger middle leaflet, an incessant rising and falling of the two
lateral leaflets, independent of external stimuli; and some of the lower
vegetables—the oscillatoria, for example,—present a constant vibratory
motion. The twining of certain plants is supposed by Palm+ to be de- pendent on their mode of growth causing the extremity of the branches to describe circles, thus enabling them to lay hold on near objects: but, however this may be, the fact that the cuscuta twines only around living plants, seems to show that, in it, this motion is in some measure
* Treviranus, Biologie, v. 201. 229. + Palm uber das Winden der Pflanzen, p. 48.
MOTIONS OF PLANTS AND ANIMALS. 4]
dependent on organic attraction; and the motions of stamens and leafstalks have too much resemblance to the irritability of muscles, not to be compared with it. Dutrochet* has discovered, that in the mimosa the irritability resides in the cortical part of a swelling situated at the articulation ôf the leafstalks. When this swelling, which exists in those mimosze only which possess this irritability, was removed, nomotion could be excited; when the upper half only was cut away, the leaf was elevated, but not depressed again. Hence Dutrochet infers that the elevation and depression of the leaf and leaflets arise from incurvation of the opposite sides of the swelling; elevation being produced by the lower part of the swelling becoming convex, depression by a similar incurva- tion of the upper part. Slices taken from the cortical part of either the upper or under half of the swelling, when placed in water, are seen to become curved. Other physiologists, Lindsay, Ritter, and Mayo, have observed a change of colour at the time of the movement, so that the phenomena might be attributed to an aflux of sap to either side of the swelling.+ Motions of animals.—There are then, in plants, organs which, by their motions, resemble either the muscles or the erectile parts of animals; but there is this difference, that the motions of animals are not merely | the result of the action of a stimulus on irritable parts, but are produced | by the internal operation of parts not endowed with motion, namely, the ` ` nerves, on those which have motion. Dutrochet, it is true, has ob- served that, when he directed the focus of a burning-glass on a single leaf of the mimosa, the impression was propagated gradually to the other leaves; and he considers the false trachez, or ducts, to be the organs which transmit this influence. But, as Treviranus justly remarks, this is merely an hypothesis; for other observers have perceived only the local effect of concentrated light, and, besides, the shock produced by the local motion may be sufficient to excite motions throughout the whole plant. | Another remarkable character of a part of the motions of animals is, that they are excited, not merely in accordance with the harmonious action, — of the whole organism, but by the voluntary operation of a single organ,| namely, the organ of the mental faculties. These motions are voluntary. Irritability again must not be confounded with sensibility. Plants are | Irritable, but not sensible; the muscles also when separated from the \ animal body are stijl irritable, but they are not sensible. Plants cannot y | be affirmed to possess sensibility, unless they manifest consciousness. | | Manifestations of sensation and voluntary motion are the sole charac- teristic mark of the simplest animals. Compound animals have often a
* Recherches Anat. et Physiol. sur la structure intime des animaux et des vegetaux.
+ Tiedemann’s Physiologie, i. 623. G. R. Treviranus, Erscheinungen und Gesetze des organ, Lebens.
A Lo”
42 DIFFERENCES OF PLANTS AND ANIMALS.
ramified and vegetable form, and are fixed by a stem to the ground; the individual faculties of the single polypes,—the voluntary motion of each polype,— indicate however, that they have an animal organisation (orga- nisatio animalis multiplicata ), and by no means that of vegetables. The movements of infusoria are free and voluntary. If, therefore, it is still a matter of doubt whether certain simple organised beings, such as the sponges and several so called alcyonia, are animal or vegetable, the absence of all voluntary motion in these bodies, whether of the whole or of indivi- dual parts of it, must determine the question, and they must more properly be numbered among the vegetable marine structures. It may certainly be said that the embryo of sponges, as Dr. Grant* has shown, like the embryo of polypes and corals, moves by means of cilia; but the distinc- tive marks between the embryo of sponges and marine infusoria are by no means certain, and similar motions have been many times observed in the embryo of true vegetables,—of the alge, for example-- The movements of the ova of zoophytes by means of cilia, are not to be regarded as voluntary; the vibrations of cilia on the branchize of some
of the lower animals are a similar phenomenon. It would appear from
the researches of Nitzscht, that some vegetable and animal products of infusions are very closely allied to each other. Thus the bacillaria pectinalis, and other species of this genus, would seem to have completely the characters of plants; while other species again have the characters of animals. Ehrenberg, however, seems not to admit the existence of such a relation between the two kingdoms; he remarks also that the active movements of alge should not be regarded as proofs of animal life, for he has never seen the moving sporules of alge take the slightest solid nutriment; and thus, according to M. Ehrenberg, the alge scattering their ova or sporules differ from monads, as a tree differs from a bird. §
* Edinb. Philos. Journ. vol. xiii. p. 382.
+ This has been observed by Trentepoil with respect to the conferva dilatata, g, Roth, or ectosperma clavata, Vauch., and by G. R. Treviranus with respect to the conferva limosa, Dillw. See Treviranus, Biologie, t. iv. p. 634. Recently Unger has repeated these observations, in watching all the transformations in the conferva dilatata;
and it appears, as Treviranus also maintains in opposition to Vaucher’s supposition, that the presence of infusoria had given rise to error, that these originally moving gemmules are again converted into alge from which they were produced. See Unger
in Nova Act. Acad. Nat, Cur. t. xiii. p. 2, p. 789, and Treviranus in the Biologie, t. iv. and in Erschein. und Gesetz. des organ. Lebens, p. 51 and 183.
‘ : This motion of the embryo of vegetables is also instanced in the Zoocarpées of Bory St. Vincent, which,
themselves jointed threads, emit germinal granules, which move about like infusoria, and then again assume the vegetable form; these he places together with the whole
tribe of arthrodiées, in a class intermediate between the animal and vegetable king- dom.
+ Beiträge zur infusorienkunde, Halle, 1817. § Poggendorf’s Annal, 1832. 1.
NERVOUS SYSTEM. 43
Professor R. Wagner is led by his own observations to adopt the same opinion; he remarks, that the motions of these germinal granules cannot be regarded as an animal act, although it appears more wonderful than the regular motions of some of the lower vegetables, namely, the oscillatoria.
Animals have a nervous system.—The sensations and other incitements to voluntary motion,—the true animal functions, in fact,—are dependent on the nervous system. The organs of animals manifest as great a depend-! ence on the nerves as the plants on light. Nerves were known to exist in| all vertebrate animals, but they had been discovered in a part only of: the invertebrata; and the opinion was very general, that the lower animals have no nerves, all the functions of sensation, motion, and di- gestion being performed by the same particles of their simple substance. The great divisibility of the lower animals seemed indeed to justify, in Some measure, this conclusion. The nerves were not known to exist in the infusoria, polypifera, acalepha, and most of the entozoa. But Otto had already described the nervous system of the strongylus gigas, a worm of the kidney. In the round worm, the nervous cord between the two vascular trunks is very evident. Mehlis has described the nervous System of the distoma hepaticum, Nordmann that of the pentastoma and diplozoa. There is no doubt but it exists in all the intestinal worms.
Tiedemann discovered the nervous system of the echinodermat that of the asterias.
complex structure in
a; at least, Lastly, Ehrenberg* has shewn the existence of a the lowest animals, the infusoria.
infusory animalcules Ehrenberg has discovered a mouth stomach; in others, mouth, intestine, and arms. rototoria, and in some infusoria, Ehrenberg has even described, and re- presented very distinctly, a kind of teeth in the mouth, male and female organs of generation, muscles, ligaments, a trace of vessels and nerves, and eye-points. These points, which Ehrenberg believes to be real eyes, are of especial importance for the question of the existence of a nervous system in the simplest animals. On the head of planariz, in which no nervous system has hitherto been discovered, exactly the same eye- dots have been seen as exist in many annelides, which are known to have a nervous system ; from which circumstance, and from the fact that the eye-dots of some nereides are really formed of an enlargement of the optic nerve, with a cup-like covering of black pigment, it is very probable
that the planarize also, and indeed all the lower animals which have such eye-dots,
In the simplest and compound In the more perfect
really possess optic nerves, and consequently a nervous System.+ It becomes indeed more and more probable that all animals,
* Organisation der Infusionsthierchen. Berlin, 1830. + If Gruithuisen believes that every dark spot of the skin has a certain relation to
the function of vision, his reasoning is quite inexact; for the first condition for
vision
l |
ES LS EEE
44 DIFFERENCES OF PLANTS AND ANIMALS.
without distinction, have a nervous system. The difficulty of distinguishing the nerves of the asterias, and of several mollusca, teaches us that we must not attribute too much importance to the fact that even in larger animals, such as the actinia and medusa, there are no distinct traces of this system. [Ehrenberg + has recently discovered a nervous system in the medusz, with red points, which he believes to be eyes. | Digestive apparatus.—Animals are distinguished from plants, however, not merely by sensation and voluntary motion. These attributes neces- sarily modify the other functions which animals possess in common with plants. This is very beautifully set forth by Cuvier. Vegetables, fixed to the surface on which they grow, absorb immediately, by their roots, the nutritive particles of the fluids which permeate them; animals, on the contrary, which generally are not fixed to one spot, but either wholly change their situation, or at least, as polypes of a solid stem, seize their food, must have the means of carrying about with them the store of fluids necessary for their nutrition. By far the greater number have an internal cavity, into which they introduce the matters intended for their nourish- ment, and in the parietes of which arise the absorbent vessels, which, as Boerhaave aptly remarked, are true internal roots.{ In some animals there is no anus, in others the existence of an intestine is doubtful. Nevertheless Mehlis states, in opposition to the common belief, that in the teenia there is a vessel-like intestine, commencing at the narrow oral orifice and soon becoming bifurcated. A well-known narrow bifurcated canal in the echinorhynchus is supposed to be the intestine. There is another cause than that above mentioned, for the necessity of a special cavity for the first process of assimilation in animals; the food of animals requires to be dissolved. The nutriment of plants is already in solution, and consists partly of water holding carbonic acid in solution, and partly of the dissolved organic matters of the soil, humus. The food of animals, consisting of compounds already organised, requires to be prepared, com- minuted, and dissolved ; hence digestion is a preparatory assimilation of the food, peculiar to animals. The circulation in plants is much more simple than in animals, and is in no case provided with a special organ for the distribution of the
is, that the optic nerve shall have a special sensibility for light, and not be a mere nerve of sensation. Those lower animals which, without having eyes, are sensible of the influence of light, can be so only by reason of the warmth accompanying the light. Hence the annelides,—for example, some nereides,—without having a transparent optic apparatus for distinguishing different objects, nevertheless have nerves for the mere general perception of light and darkness ; and the mere existence of optic nerves for the general perception of light in an animal which, from the absence of optic apparatus, can distinguish no definite object, is a strong proof that the perception of light is always
connected with special nerves. See my Observations on the structure of the eye of the Nereides,—Annal. des Sciences Nat. t, xxii, p. 19.
t Miller’s Archiv. 1834, p. 571. + Cuvier, Anatomie Comparée, t. i.
z CIRCULATION. —RESPIRATION. ; 45
fluid, namely, a heart. In some simple plants there is a rotatory motion of the sap in the interior of internodia and in cells. Corti discovered this motion in the chara, and his observation has been confirmed by Fontana, by G. R. and L. C. Treviranus, Amici, C. H. Schultz, Agardh, and Raspail; Meyen has discovered a similar motion in the cells of the vallisneria spiralis, and in the hairs of the radicle fibres of hydrocharis morsus rane. In the higher vascular plants Professor Schultz* has discovered a continuous motion of the sap, which according to Schultz, is a true circulation, ascending in one vessel, and descending in the other; the two streams, however, communicating by cross branches between the different vessels. In fine sections of the leafstalk of many plants it may also be distinctly observed that the course of the sap is different in different vessels; and this I have seen very distinctly even in fine sections of the leafstalk of fig-leaves. Whether the section, whether the division of the vessels, has not some share in determining the direction of the currents, can be ascertained only by observing the different currents in uninjured leaves. In leaves of the chelido- nium which were still in connection with the living stem, I have cer- tainly seen currents in opposite directions. The circumstance observed by Dutrochet, that an ascending and descending rotatory motion is produced in a perpendicular thin glass vessel filled with water, when it is heated differently at different parts, cannot be applied to explain the motion of the sap in plants; for in that case the sole cause of the rotatory motion is the ascent of the heated and expanded molecules of water. It appears, therefore, that the motion of the sap in plants is effected, in some manner at present not understood, by attraction and repulsion, exerted in the leaves on the one hand, and in the roots on the other. It is certain, however, that light exerts an attraction upon the Sap, since it evidently determines the growth of the whole plant.
The circulation in animals, on the contrary, derives its impelling force, hot from external influences, but from the contraction of a central organ, the heart. It is still uncertain whether a perfect circulation is an absolute predicate of animals; at all events, in many simple animals neither heart nor vessels have at present been discovered.
T he respiration of animals and plants affords a very important dis- tinctive character. In plants, and in the most simple animals, respiration is performed by the entire surface ; but in the more perfect animals the surface is not sufficient for the necessary aeration of the fluids, and an ee is required, which in a small space shall afford an immense super- ficies for contact with the atmosphere. But the products of respiration in the vegetable and the animal kingdom are also different. In plants the
* Ueber den Kreislauf des Saftes im Schéllkraut. Berlin, 1822.—Die Natur der lebendigen Pflanze. Berlin, 1823.—Annal. des Sc. Nat. t. xxii. p. 75, 79.
46 PROPAGATION OF PLANTS AND ANIMALS.
assimilation of nutriment consists partly in the conversion of binary compounds, carbonic acid and water, into ternary compounds of the elements of these substances—into vegetable matter, in fact. In this process an excess of oxygen remains, which is then exhaled by means of the leaves. The leaves also absorb carbonic acid from the atmo- sphere, as has been proved by the researches of Priestley, Scheele, Ingenhouss, Spallanzani, Sennebier, Humboldt, and De Saussure. By the action of the leaves, the carbonic acid contained in the atmo- sphere is decomposed ; the carbon and a part of the oxygen combine with the plant, while the greatest part of the oxygen is restored to the air. During the night, and in the shade, as well as in an unhealthy or fading condition, plants absorb a part of the oxygen of the atmosphere and exhale carbonic acid ; but the quantity of carbonic acid thus ex- haled is less than that which they ordinarily absorb during the day.* Respiration, then, in plants appears merely to serve for the correction of the assimilating process. The respiration of plants also removes from the atmosphere a part of the carbonic acid formed by animals, and yields to it an abundance of oxygen. Animals are nourished by organic matter only, not by inorganic matter; and besides carbon, oxygen, and hydrogen, nitrogen also, which in many plants is quite wanting and in others exists in very small quantity, enters into the composition of animal matter. From the circumstance that a large quantity of animal matter is constantly undergoing putrefaction, and is thus converted into binary compounds, while animals are quite incapa- ble of generating new organic matter from simple elementary bodies or binary compounds, it is evident that plants, which have the latter power, are absolutely necessary to animals, just as animals on the other hand are indispensable for the existence of plants; for animals exhale that which plants inhale, namely, carbonic acid, and inhale that which is exhaled by plants, namely, oxygen. Hence, without the existence of the vegetable world, the atmosphere would become irrespirable for animals; while, by the reciprocal action of plants and animals, the com- position of the atmosphere is preserved nearly absolutely unchanged. Propagation by shoots and by division in plants.—Plants, having only one mode of manifesting life, namely, by vegetation, do not require mani- fold organs in addition to their roots, stem, and leaves ; and, with the ex- ception of the organs of fructification, present merely a repetition of perfectly similar parts, in all of which the simple relation of branches to leaves is the same; and even the sexual organs are evidently allied to the leaves, and in some cases are transformed into them. Moreover, a consequence of plants thus presenting before fructification merely a re- petition of similar parts united by one stem is, that each of these parts
* Tiedemann’s Physiology, Translation, p. 118. Gilby, Edinb. Phil. Journ. 1821, 7.
48 : FUNCTIONS OF ANIMALS.
phenomena comprehends the processes which lead to the formation of new germs in an individual, and to the separation and developement of these germs; and consequently have for their object the preservation of the species, while the individuals perish.
The above mode of classification has its advantages, but may give rise to misconceptions. The force which determines the developement of the germ is identical with that which is the source of the constant preser- vation and renovation of the individual. The primary forces of the animal body would, therefore, appear to be the vegetative, the motor, and the sensitive forces; but it is again a question whether even this is not an artificial division.
It can be conceived that the essential principle of vegetable life,— the vegetative force, — may be combined in animals with other forces, namely, with the sensitive and motor, or with the nervous power, if the contractile power of the muscles is regarded as derived from the nerves, and not inherent in themselves. It may be imagined that these forces are united in the germ, and that, from the period of developement, they manifest themselves in the different systems of organs, which react on each other; so that the vegetative, directed by the nervous force, re- produces and constantly preserves the organs of nervous life as well as other parts, while the nerves again give sensibility to the parts organised by the vegetative force. If, however, this theory be reconsidered, it will be seen to involve contradictions.
It is much more probable that these apparently distinct forces are merely different modes of action of one and the same ‘vis essentialis’ resident in the animal, which modes of action are determined by the different composition of the organs. There is indeed an absurdity in the very idea that the nutritive force forms the nerves, and that the action of these nerves, when formed, results from a force distinct from that which formed them. The vital force creates in animals all the essential parts, and generates in them that combination of elements, the result of which in the nerves is the power of motion and sensation, or the power of conveying impressions to a central part, and reflex actions from it. / The organs endowed with the power of assimilating matters which are | destined for the use of the indivisible whole, the organs of motion, and the organs by means of which a central organ receives impressions from all the other organs and transmits its reflex actions, are only the differ- ent products of this first and sole principle of animal existence,—the primum movens, which produces and reproduces all parts of the body. The first set are the organs subservient to the renovation of the body, the second the muscles, the third the nerves. - Then there are also parts which receive from the creative organic force merely the physical pro- perties of hardness, elasticity, toughness, &c. —for example, the bones, cartilages, ligaments, and tendons.
CLASSIFICATION OF FUNCTIONS. 49
The glands, for example, by nutrition and reproduction, acquire the Property of attracting certain parts of the blood, combining them anew, and separating them from that fluid. By the same process of nutrition and renovation, the muscles acquire the property of contracting on the
—a property which is the result of nutrition, iple distinct from the organic creative force. rves receive the power of manifesting their n are merely the results of nutrition,
Systems of the animal body may b
l. Organs which change the chemical composition of the fluids for the purposes of the general System; such are the secreting organs, the blood-vessels and lymphatics, and the lungs. The peculiar function performed by these organs is not nutrition, for this is performed in all
the organs of the body, but the change of the organic combination of the elements in fluids which are in contact with th
em, by exerting an organic affinity.
2. Muscular organs, fluences, their fibres be where a change of their has named the propert influence of mechanic
irritability has been an irritability in the nerves, irritability, at another their sensibility, could undergo a change. In the living body the action of the muscles always determined by their nerves, and Composition of the nerves, although but as it were, of the nervous force,
is every cause which changes the slightly, produces a discharge, and, as the result of this, a contraction of the muscles. Hence the study of muscular motions, and of spasmodic and paralytic affections generally, leads to the investigation of the laws which regulate the action of the nerves. Motion accompanies all changes of composition ; rocesses of formation, nutrition, and
xerted between the blood and the
; t in this manner, although not essen- ti power from muscular substance, particularly intermixed with their tissue ; such parts are
the efferent which are distinctly contractile,
E
`
FUNCTIONS OF ANIMALS, \ 47
has the power of becoming in its turn an independent living body when separated from the rest of the plant; for, besides the generation by seed, there is here a generation by shoots. The seed also is an inde- pendent part; the only essential point in which it differs from a shoot being, that in the seed the vegetative power is great, while vegetative action is very imperfect, or even does not exist.
In animals, on the contrary, the reciprocal action of circulation, res- piration, and the nervous system, is actually necessary to life. The respi- ratory movements are dependent on nervous influence : do not exert this influence unless supplied with blood aerated in the lungs; and the blood again is not sent organs, and therefore not to the nerves, heart are performed; while the heart in fluence of arterial blood
but the nerves which has been to the different without the contractions of the its turn is dependent on the in- and of the nerves. The brain, heart, and lungs are therefore, as it were, the main wheels of the animal machine ; which ‘wheels react one on the other, and are set in motion, as it were, by the change of material which takes place in respiration. The growth of ani- | mals also is not effected by an external protrusion of new parts, but ge- nerally by enlargement of the whole animal—by increase in size of each original part internal as well as external. The compound polypiferous animals afford the only example in the animal kingdom of the mode of. growth by new shoots. Most animals, and especially the more perfect, do not constitute an aggregate of similar parts united by one trunk; on the contrary, they contain parts of very different vital properties; and this circumstance renders propagation by division in them impossible, unless, as in the case of polypes and some annelides,—as the nereides and naides,— each of the separated portions still contains the essential parts of the whole. The object of the entire of the foregoin to show how the possession of new propert even those functions which are common t
Classification of the Junctions of animals —The comparison of animals
with plants suggested to the earlier physiologists their the functions of animals,
The functions whi have been called org and maintenance of
g comparison has been merely ies by animals modifies in them o them and plants.
mode of arranging
ch plants and animals appear to possess in common, ante or vital ; they have for their end the production all the separate parts in the self-existing whole. They ions of organic affinity in the operations of the organic The functions which especially distinguish animal beings,
Sensation, motion, thought, &c. appear to be the end of animal
existence; these functions it is which would characterize the animal, although it exis
ted only a moment. The ancients named them animal, in contradistinction to the former, organic functions. A third series of
or vital force, namely,
50 ORGANIC ATTRACTION.
3. The nerves are in part motor, in part sensitive. The motor nerves are those which, under the influence of changes in their condition so slight as to elude the perception of the observer, excite motions in the muscles: the sensitive nerves are those which have the faculty of com- municating every change which they suffer to the brain, the central organ, from which again certain influences are transmitted to all the other organs of the body. Many nerves, arising from the brain and spinal marrow, are, while in connection with these organs, voluntary excitors of motion in the muscles; while, under the influence of a change in their condition they may become excitors of involuntary muscular contractions, whether the connection between them and the brain and spinal cord is still maintained, or not. Those parts, on the contrary, which are endowed with motion, and are dependent on the sympathetic nerve, are withdrawn from the power of the will, and are only, in a certain degree, dependent on the brain and spinal marrow, through the medium of the connection of the sympathetic nerve with cerebral and spinal nerves. It is in the nerves that the mobility of the organic forces, without motion of the ponderable masses, is most manifest ; their operation is necessary for the exercise of all the functions of the body, since all parts of the system, through the - medium of changes produced in the nerves, react on the brain and spinal marrow, and receive from these organs certain influences necessary for their peculiar actions. ;
These systems of organs are interwoven in different manners one with another. The sensibility of any part is solely owing to the nerves which enter into its composition: the organs which serve to produce chemical changes in the fluids, if contractile, are so only by virtue of the muscular fibres which they contain; and when there is a secretion of fluids in a part endowed with other peculiar vital properties, there is always a peculiar tissue for this purpose; such, for example, is the case in the organs of sense, in which fluids are secreted by special tissues.
Organic attraction: —The reciprocal action of these systems of organs, and their nutrition from the blood, cannot take place without the mani- festation of affinity in the ponderable and imponderable matters, toge- ther with organic attraction. A knowledge of the laws of this attrac- tion would be of the greatest importance; but the facts relating to it which we are acquainted with, although remarkable, are very few in num- ber; such are the attraction of the blood into parts which are capable of erection and which are at the time in a state of excitement, and that remarkable mode of union of germs by which a part of the double mon- sters are to be explained. Such a union of the germs could not have taken place without an attraction having been exerted between similar parts; for in almost all cases the monsters are united by their corre- sponding parts, face with face, snout with snout either by the anterior or lateral surface, occiput with occiput either by the middle or side,
ANIMAL EXCITABILITY. 51
neck with neck, breast with breast, or merely belly with belly, or side with side, or merely buttock with buttock; the uniting parts of the two embryos, in these cases, always becoming single, while the cavities of the two are double. A single actual observation of this organic at- traction between minute parts would be of the greatest importance. But all my endeavours to obtain this desideratum by experiment have been fruitless: I placed the nerve ofa frog exposed and dissected out under the microscope, and watched the end of the nerve while sur- rounded by blood-globules; again I placed some semen of the frog with portions of the unimpregnated ovum under the microscope; but in neither case could I perceive anything like organic attraction.
Animal excitability The laws of the excitability of organic beings generally, have been investigated in the former section; the relations which the vital stimuli bear to the manifestations of life have been there determined. The laws of the excitability of animals will be here more particularly set forth, although in the present state of science it is scarcely possible to throw any light upon this difficult problem, a know- ledge of which however is so desirable, since it is here that practical medicine has much to expect from physiology.
Whether the vital principle or organic force is the result of the combi- .- nation of ponderable and imponderable matters, or itself determines and maintains the peculiar composition of organic matter, it is an observed fact, that under certain circumstances this force becomes strengthened in particular organs, of which in this case the action becomes greater and more continued, as is observed in the genital organs during preg- nancy and the sexual ardour. Thus also the organic force is observed to become less in the antlers of the stag just before they fall off, and to be again increased when they are reproduced in an organised state. An accumulation of organic force in a part is accompanied by an in- creased afflux of blood, and a more abundant conversion of blood into Organised matter. Tiedemann remarks, that an organ in an excited State undergoes more rapid changes in its material composition, and therefore attracts more quickly and in larger quantity the blood, which alone is able to render an organ capable of increased vital action.” When, on the other hand, any organised part has suffered a lesion from change in its material composition, in that case also if the destruction of Organised texture has not been too great, increased action ensues for the Purpose of restoring the healthy state.. Organised beings have the power of preserving in all parts the composition necessary for the life of the Whole. When the composition is disturbed, the curative effect of this Power is manifested. This is a necessary consequence of the law, that in organic bodies there is a constant striving to counteract chemical affinities. Hence the increased flow of blood to an injured part arises
F Flode TE bal * Tiedemann’s Physiologie, i. p. 326.
BQ
52 ANIMAL EXCITABILITY.—EXHAUSTION.
from the organic action in it being increased. The reciprocal action of the increased organic process, and of the commencing tendency to decomposition in the part, on each other, is seen in inflammation. In- flammation is not essentially a state of increased action, but is com- pounded of the phenomena of the local injury, a tendency to decom- position in the part and increased vital action striving to balance the destructive tendency. When the degree of change of composition in the animal tissues is greater, reaction does not ensue, and inflammation is not produced; such is the case in death by narcotic poisons. When inflammation does occur, the change produced by the injury may soon become so great that the organic reaction is not able to counterbalance it, and local death ensues.
Exhaustion. —These and many other cases, even the fatigue and ex- haustion which follow great exertions, show that the organic force is consumed as it were by the exercise of the functions. This circum- stance is evident even after death ; for if we take two similar portions of muscle of an animal just killed, and excite in the one slight contractions with a knife, while the other is left unirritated, the first portion will lose its irritability sooner than the other, and the difference will be proportionate to the number of contractions which have been excited in it.* In the same way every impression of light deadens the power of vision in some degree, and an equal stimulus immediately afterwards does not produce an equal reaction; the eye requires rest.
This might be explained by supposing that a part of the organic force is exhausted in balancing the material changes produced by the sti- mulus. But exhaustion also ensues when the action of an organ is in- creased without any external stimulus, if the organic force is not increased at the same time. It appears, therefore, that the very action of organs produces a change in their composition. It may be that the constant change which is produced in the organic substance by the action of the arterial blood, and which is as necessary to life as the decomposition of the burning matter is to the phenomenon of combustion, is accelerated or increased by the action of the organ, while the renovation from new nutritive matter does not take place with proportionate rapidity, and can only be effected gradually during rest. Generally, however, the more exertion a man uses, the more active seems to be the decomposition of the matters in his body, and the more need has he for nutriment. Both men and brutes that have died after very violent exertion, as in the instance of a stag hunted to death, undergo putrefaction much sooner than animals bled to death. Autenrieth,+ who makes this remark, also instances, that a muscle taken from an animal before irritability had ceased, putrefies much sooner if stimulated to frequent contractions,
* Autenrieth’s Physiol. i. 63.
t Physiol, i. 115. See also Humboldt über die gereiate Muskel und Nerven-faser.
EFFECTS OF EXERCISE. 53
than if left at rest. In the functions of the nervous system especially, rest is so necessary, that even a life the most tranquil requires sleep, Which comes on even while the causes which excite the nervous system to action, namely, the external stimuli, are in Operation ; the nervous system being rendered insensible to these impressions by reason of the change induced in it by its state of activity.
The constant reanimation of the tissues by the general vital stimuli ordinarily renders them capable of a proportionate exercise of their func- tions; but if their action is increased and accelerated, subsequent rest is necessary to restore as much power for new action as has been thus consumed.
Exercise.— Generally, in the healthy state, just as much power ig generated in a certain space of time as has been exhausted by the exer- cise of the functions ; but there are cases in which the nutrition of the organ becomes gradually increased while the state of action is either equal and regular, or alternating with rest. This is the case, for instance, in youth, because the affinity of the tissues for the vital stimuli seems, for reasons already stated, to be greater when the developement is less complete: indeed, ceteris paribus, the power of an organ is always in- creased by exercise, not carried too far, and alternating with rest ; while mere rest often weakens an organ. This alternation of exercise and rest is the means by which a gradual increase of strength is to be acquired. Life generally is attended with decomposition of organic matter; in the same way, perhaps, the action of an organ is attended with decomposition of a part of its material, while another part be- Comes more intimately combined, so that, although an organ really loses matter by its state of action, still the same action renders it more capable of attracting new material and of strengthening itself. But when the action is repeated too frequently and violently, the renovation of material-is even less, and exhaustion ensues. This is the case when the vital force is consumed, or rendered inert, by in- creased action, more quickly than renovation can be effected. “ie exhaustion is so much the greater, the more numerous and the more im- Portant the parts of which the action is thus frequent and violent, as, for example, in coitus, in which nearly the whole nervous system is thrown into a state of activity, attended with consumption of vital force; and the more the action of the organ is attended with a loss of Something which it imparts to another part, as seems to be the case in the action of the nerves; and, lastly, the more the action of the part IS attended with a real loss to the whole System, as in the case of increased secretions, for example, of the milk. The momentary ies of inertness of the vital force after action, and its gradual restoration, 1s seen even in parts of frogs separated = eee a i gee bility being restored probably by the action of the blood still con-
nnne : Sm Sc eae
ae
5A » ANIMAL EXCITABILITY, —REACTION.
tained in the part, as well as by that of the air on the tissues. Thus the repeated application of galvanism to the leg of a frog separated from the animal exhausts its irritability, which is again restored after a certain interval of rest. l
If an organ is very rarely called into action, its power is not restored by rest in the same degree as when it is subjected to more frequent exercise. The eye, for example, requires rest after being in action ; but by alternating exercise and rest it is strengthened. If the eye is kept long in complete rest, it will have acquired great sensibility ; but the vital force will have become weaker in proportion to the time that it has been left without exercise; and a strong impression of light will be sufficient even to blind an eye which has thus been kept long in darkness. Muscles lose much of their motor power by want of exercise; the power of the muscles of the ear, for instance, is lost for want of being exer- cised.* ;
Reaction—Hitherto change in the organic activity of animals has been considered merely in a general manner. The operation of external in- fluences in producing change in this property of animals shall now be investigated. The external “ vital stimuli” are not the only agents which give rise to vital actions; everything which disturbs the elementary composition of organs, and the balance in the distribution of impondera- ble matters in the organic tissues, may also modify the action of the organism and of the separate organs. Such a modification when consi- derable is called reaction ; the influence which produces this reaction in the organism is called irritation ; and the cause exciting this irri- tation, the stimulus or irritant. The reaction is always a vital pheno- menon, a manifestation of an organic property of the animal system. The property of reaction, of being excited to the manifestation of some inherent power on the application of an external influence, is not con- fined to organic beings, and still less to animals. Light or warmth are developed from many inorganic bodies, under certain circumstances, for example, by a blow. In these cases it is probable that the light and caloric existed in the bodies in a combined state, and are set free by the action of the external influence. A still better instance is afforded by elastic bodies, the minute particles of which have such an attraction for each other, that an attempt to displace a portion of them acts upon the whole; and by the power of attraction between them a restitutio in integrum ensues, accompanied with the phenomena of elasticity or sono- rous vibrations. But no inorganic bodies are so uniform in their mode of reaction as the organised bodies, which, under disturbing influences, however various, always manifest the same phenomenon,—that, namely, with the capability for which each organ is endued by life. The uni- formity in the mode of reaction of organised bodies arises probably from
a e
|
* Autenrieth, Physiol. i. 104.
EFFECTS OF EXCITEMENT. 55
that fundamental property resident in them, of counterbalancing disturb- ances in their composition, by a force which, in the healthy state of the body, is much stronger than the disturbing cause. The force which restores the balance in the composition of the tissues after such a dis- turbance, is identical with that which preserves all the properties of a part during the constant process of nutrition and renovation of material. The phenomenon which ensues on the restoration of the balance, is con- stituted partly by the change produced by the external cause, and partly by the effort exerted to restore the balance. Dutrochet* maintains that all stimulants produce the same change in the organism,—that they modify the state of oxidation of the organic matter on which they act ; the stimulant, he says, acts simultaneously on the oxygen and the organic matter, causing them to unite. Ingenious as this theory is, it is at pre- sent a mere hypothesis ; as is also the conclusion that Dutrochet comes to, namely, that excitability is really a state of susceptibility of oxida- tion.
Irritation ofan organ must always be attended with some material change in it. Such a change indeed must be presupposed even in the effect of the stimulus of light upon the eye. Light appears to enter into the com- Position of many bodies, and produces chemical changes, which are evident in several chemical preparations, and even in plants, in which light causes the developement of oxygen. The immediate effect which
a stimulus produces, varies with the nature of the stimulus and of the body irritated; thus, it may be compression or a chemical change. But the secondary effect—the effort to counteract the former—is quite independent of the nature of the stimulus, is not mechanical or aie. mical, but is a manifestation of the vital property of the organ, such as sensation, manifested by pain, or inflammation, or spasm. Caloric, electr icity, and light are imparted to organised beings according to the general laws of physics; but in the “ restitutio in integrum” there always arises, at the same time, a vital action, which differs in its kind accord- ing to the part that has undergone the change; and the phenomena observed, until the part is restored to its natural state, are compounded of the operation of the stimulus and the reaction which it has excited, Chemical substances also produce a change in organic bodies, and have à tendency to form binary compounds with their elements. If this Ccurs,—if the organic affinity is not able to counteract the chemical agéncy,—a chemical product is formed, at the same time that the life of the part is destroyed, as is observed in the case of burns, and of the application of mineral acids or a caustic alkali. But the organised struc- ture, thus acted upon by a chemical agent, while it retains its life, and. on the boundaries of the part after its death, manifests the organic pro- Perties peculiar to it, such as sensation, motion, or inflammation.
* Froriep’s Notizen. 724. Séances de l'Acad. d, Sc. Jan, 30, 1832.
ee Sa meet
| f
56 REACTION.—SYMPTOMS,
The reaction of animal bodies on the application of external stimuli is peculiar, not merely in being manifested by vital properties, but these vital properties are frequently different, according to the nature of the organ and of its composition. Thus, for example, mechanical, chemical, or electrical stimuli applied to a muscle, all produce in it the same mode of reaction, namely, motion. So, also, all the different stimuli applied to a sentient nerve, excite sensation merely; and the kind of sensation is very different in different nerves, when the exciting cause is the same, and the sensation produced in the same nerve is always the same, although the exciting causes be different. Thus, for example, mechanical and electric stimuli excite, in the optic nerve, the perception of light, which is the pe- culiar property of this nerve, and seem to excite no pain; while pain, and not the perception of light, is the constant result of irritation of a sentient nerve. In the same way, mechanical and electric stimuli produce in the auditory nerve the perception of sound, and electricity excites in the olfactory nerve the sensation of smell. The anterior roots of the spinal nerves when irritated mechanically or by galvanism, give rise to no sen- sations, but to muscular contractions; while the posterior roots of the same nerves, under similar circumstances, excite sensations only, no contraction of muscles. By knowing the mode of reaction peculiar to all parts of the body, physiology acquires an empirical knowledge as certain as any possessed by the other natural sciences.
In perfectly different diseased states of the same organ the symptoms are often very similar; for in a state of excited action, as well as ina state of irritation with diminished power, the organ will manifest the vital properties peculiar to it. There are certain groups of cerebral symptoms, and of symptoms of cardiac disease, which occur in very different morbid conditions of each of these organs respectively. We may here remark upon the folly of the homceopathists, who imagine that they can cure dis- eases by means of substances which shall produce states of the system re- sembling the diseases; while they either do nothing whatever, or nature applies the remedies otherwise than the homeeopathist imagines. The fact of two substances producing similar symptoms in one organ does not prove that these substances produce exactly the same effects, but merely that they act