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NUNQUAM ALIUD NATURA, ALIUD SAPIENTIA DICIT. 


CONTRIBUTORS. 


J. S. EDKINS, M.B., Lecturer on Practical Physiology in St. Barthol- 
omew’s Hospital Medical School, London. 


ARTHUR GAMGEE, M.D., F.R.S., Emeritus Professor of Physiology 
in Owens College, Manchester. 


W. H. GASKELL, M‘D., LL.D., F.R.S., Lecturer on Physiology im the 
University of Cambridge. 

FRANCIS GOTCH, B.Sc., F.R.S., Waynflete Professor of Physiology 
in the University of Oxford. 

ALBERT A. GRAY, M.D., University of Glasgow. 


W. D. HALLIBURTON, M.D., F.R.S., Professor of Physiology in King’s 
College, London. 


J. BERRY HAYCRAFT, D.Sc, M.D., Professor of Physiology in 
University College, Cardiff. ; 


LEONARD HILL, M.B., Lecturer on Physiology in the London Hospital 
Medical School, ender: 


F. GOWLAND HOPKINS, B.Sc., M.B., Demonstrator of Chemical 
Physiology in Guy’s Hospital Medical School, London. 


. N. LANGLEY, D.Sc., F.R.S., Lecturer on Physiology in the Universit 
Me 


f Bigitized ny th Internet Archive 
1 eles Ae Uadlleeine te tf futidirigy fro rte °" of Physiology in 


B. MOORE, a fa University 


College, London. 


D. NOEL PATON, M.D., Lecturer on Physiology in the School of 
Medicine, Edinburgh. 


M. S. PEMBREY, M.D., Lecturer on Physiology in Chanes Cross 
Hospital Medical Echool, London. 


E. WAYMOUTH REID, M.B., Professor of Physiology in University 


College, Dundee. 


W. H. R. RIVERS, M.D., Lecturer on Physiological Psychology in the 
University of Cambridge and in University College, London. 


J. BURDON SANDERSON, M.D., D.C.L., F.R.S., Regius Professor 
of Medicine in the University of Oxford. 


E. A. SCHAFER, LL.D., F.R.S., Jodrell Professor of Physiology in 
University College, London. 


C. S. SHERRINGTON, M.D., F.R.S., Holt Professor of Physiology in 
University College, Liverpool. 


E. H. STARLING, M.D., Joint-Lecturer on Physiology in Guy’s 
Hospital Medical School, London. é 


http://www.archive.org/details/textoookofphysio01 sharuoft 


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IFRy 
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PERT BOOK <\'% 


OF 


PHYSIOLOGY 


) EDITED BY 
i 


(.S,) E* AY SCHAFER, LL.D. ERS. 


JODRELL PROFESSOR OF PHYSIOLOGY, UNIVERSITY COLLEGE, LONDON. 


VOLUME FIRST. 


EDINBURGH & LONDON: 
WOU BiG aa be Ne eA ND. 
1898. 


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38 WEST 8} LD, LONDON, E.C., BY MORRIS "AND 
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PREFACE. 


——_>— 


THE want of a text-book in the English language to which students 
could turn for information beyond that contained in the ordinary 
manuals has long been felt by teachers of physiology in this country. 
The most extensive of the existing text-books do not aim at giving 
the full and precise information nor the references to original 
authorities which are required by the advanced student. It has 
hitherto been necessary for those who seek such information to consult 
original articles—an operation which frequently involves a familiar 
acquaintance with foreign languages and an expenditure of time rarely 
at the disposal of the student. The present work is not intended 
altogether to supersede this consultation of original papers, but will, 
it is hoped, reduce the need of it to more reasonable limits, and will, 
moreover, by the references to literature which throughout form an 
important feature of each article, facilitate such study where it is still 
necessary. 

A book of this character, from the enormous amount of literary 
labour which is involved in its production, and from the progressive 
character of the science with which it deals, could hardly be undertaken 
by one person. The editor has been fortunate enough to secure the 
co-operation of many of the leading physiologists in this country, each 
of whom deals with some branch of the subject to which he has given 
special attention. Accordingly the reader will find in each article, in 
addition to information as to the present state of knowledge as com- 
plete as it has been possible to make it, many original observations 
upon the matter to which it relates. 

The subjects of generation and reproduction have been omitted in 
this text-book, because, although strictly speaking appertaining to 
physiology, they are studied almost entirely by morphological methods, 
and are more conveniently treated in connection with morphology. It 
has therefore been decided that it would be better not to swell the bulk 
of these volumes, which have already grown beyond the limits originally 
intended, by the introduction of subjects such as these, which possess 
an enormous recent literature, and are exhaustively dealt with in 
special works accessible to every student. The same remark will apply 
to the general physiology of the cell, a branch of biology which has 


= PREFACE. 


of late attained so great an extent and importance as to necessitate 
text-books devoted to itself alone, and which it is usual to study rather 
as an introduction to, than as a part of, animal physiology. 

Of the two volumes of which it is intended this book shall consist, 
the articles in the first volume deal mainly with the chemical constitu- 
tion and the chemical processes of the animal body, and with those 
physical and chemical phenomena which are connected with the pro- 
duction and elaboration of the secretions and other fluids of the 
body. The articles in the second volume include the mechanics of the 
circulation and respiration, and of special muscular movements; the 
general physiology of muscle and nerve; the special senses ; and the 
functions of the central nervous system. 

It is nearly twenty years since the publication in six volumes of the 
important “ Handbuch der Physiologie,” under the editorship of Pro- 
fessor L. Hermann. The articles in that book, as in this, were under- 
taken by physiologists who were specially conversant with the particular 
branches of the science with which they severally dealt ; and since most 
of the articles in it are prefaced by short historical introductions, 
and interspersed with abundant references to the literature of the 
subject, the whole work constitutes a storehouse of information, 
which has proved of great value to teachers and investigators. But 
the size of the work, and the fact that it is written in the German 
language, have limited its utility to students in this country ; moreover, 
in the course of the twenty years that have elapsed since its appearance, 
rapid progress has been made in every branch of physiology, so that 
several of the articles in it have been long out of date. Nevertheless 
its publication served both to lay a firm foundation for the exposition of 
the science in its modern aspect, and also to clear the ground for all 
future publications of a similar character. It has thus been a marked 
advantage, in preparing many of the articles for the present book, to have 
had the work of Hermann and his coadjutors to refer to; and although 
due acknowledgment is made both of this and of other sources of infor- 
mation in the articles themselves, it has seemed right specially to 
mention the “ Handbuch” in this preface. 


University CoLLece, Lonpon, 
February 1898. 


CONTENTS OF VOLUME FIRST. 


THE CHEMICAL CONSTITUENTS OF THE BODY 
AND FOOD. 


By W. D. HALLIBURTON. 


The Carbohydrates—The Fats—Lecithin—Cholesterin—The Proteids—Decom- 
position Products of Proteids—Synthesis of Proteids—Theories of Proteid 
Constitution—General Properties and Reactions of Proteids—Classification 
of Proteids—Vegetable Proteids—Poisonous Proteids—Compound Proteids 
—The Albuminoids—Inorganie Compounds. , : : ; page 1 


THE CHEMISTRY OF THE TISSUES AND ORGANS. 
By W. D. HALLIBURTON. 


Cells and Protoplasm—Liver—Spleen—Thymus—Thyroid—Suprarenals—Pancreas 
—Kidneys—Testis—Muscle—Skeletal Tissues—Nervous Tissues—The Eye— 
Milk . : : ; é : : ; ‘ : : ; . page 80 


THE BLOOD. 
By E. A. SCHAFER. 


General Properties—Amount—Colour—Specific Gravity—Reaction—Coagulation— 
Relative Amounts of Plasma and Corpuscles—Number of Corpuscles—General 
Composition of Blood—Composition of Blood Corpnscles—Composition of 
Plasma—Proteids of Plasma—Theories of Coagulation—Causes of Coagulation 
—Lymph and Allied Fluids. : ; : : : : . page 141 


HAMOGLOBIN: ITS COMPOUNDS AND THE PRINCIPAL 
PRODUCTS OF ITS DECOMPOSITION. 


By ARTHUR GAMGEE. 


Distribution in the Animal Kingdom—Relations to other Constituents of Red 
Corpuscles (Arterin and Phlebin)—Oxyhemoglobin—Methods of Obtaining 
—Composition of—Crystalline Form—Action of Reagents on—Spectrum— 
Spectrophotometry—Photographie Spectrum—Hzemoglobin—Preparation of— 
Colour and Spectrum—Compounds with Gases—Derivatives and Products of 
Decomposition . : A : P : : : E : . page 185 


Xil CONTENTS. 


A GENERAL ACCOUNT OF THE PROCESSES OF DIFFUSION, 
OSMOSIS, AND FILTRATION. 


By E. WAYMOUTH REID. 
Diffusion—Osmosis— Filtration ; : : : : : ; . page 261 


THE PRODUCTION AND ABSORPTION OF LYMPH. 
By ERNEST H. STARLING. 


The Production of Lymph—The Physical Forces concerned in the Movement of 
Lymph—The Absorption of Lymph from the Connective Tissues—On the 
Functions of the Lymph in the Nutrition of the Tissues . < » page 285 


CHEMISTRY OF THE DIGESTIVE PROCESSES. 
By B. MOORE. 


Digestive Ferments—Chemical Composition of Digestive Juices—Saliva—Gastrie 
Juice—Pancreatic Juice—Intestinal Juice—Bile—Digestion of Carbohydrates 
—Digestion of Proteids—Absorption of Carbohydrates and Proteids— 
Digestion and Absorption of Fats—Bacterial Digestion—Composition of 
Feeces : ; < 2 : : : . : : : . page 312 


THE SALIVARY GLANDS. 
By J. N. LANGLEY. 


Anatomical Characters—Histological Characters—Origin and Course of Nerves— 
Changes during Secretion—Reflex Secretion—The Dyspneiec Secretion— 
Stimulation of the Cranial Nerve—Stimulation of the Sympathetic Nerve— 
The Augmented Secretion—Effect of Protracted Stimulation on the Amount 
and Percentage Composition of Saliva—Relation of the Rate of Secretion to 
the Percentage Composition of Saliva—Some General Characters of Saliva— 
Substances secreted in Saliva—Effects of the Cranial and Sympathetic Nerves 
upon the Blood Flow—Mutual Effects of the Cranial and Sympathetic Nerves 
upon Secretion—Effect of Variations in the Amount and Quality of the Blood 
supplied to a Gland—Relation of Secretion to the Flow of Lymph—The 
Secretory Pressure—Reflex Inhibition of Saliva—The Action of Alkaloids— 
Formation of Heat—Electrical Changes—Section of Glandular Nerves—The 
Paralytic Secretion—Secretion due to Reflex Action of Peripheral Ganglia 
—Direct Irritability of Gland Cells—Extirpation of the Glands—Injection 
into the Blood of Saliva and of Gland Extracts—General Considerations— 
Theories of the Mode of Action of Secretory Nerves. é . page 475 


MECHANISM OF SECRETION OF GASTRIC, PANCREATIC, 
AND INTESTINAL JUICES. 


By J. 8. EDKINS. 


Histological Appearances accompanying Secretory Conditions of Stomach—Functions 
of the Cells and Regions of the Stomach—Methods of obtaining Gastric Juice— 
Influence of the Nervous System on Gastric Secretion—Conditions which 
provoke Secretion—Formation of the Ferments of Gastric Juice—Formation 
of Rennin—Variations in Gastric Juice during Digestion—Histological Appear- 
ances of the Secretory Conditions of the Pancreas—Influence of the Nervous 
System upon Pancreatic Secretion—Conditions which provoke the Flow of 
Pancreatic Juice—Ferments of the Pancreatic Juice and their Antecedents— 
Variations in Pancreatic Juice during Digestion—Evidence of Secretion in the 
Intestine . ‘ : : é : : : : : ‘ . page 531 


CONTENTS. Xili 


MECHANISM OF BILE SECRETION. 
By D. NOEL PATON. 


Mode of Formation of Bile Constituents—Water— Inorganic Salts—Nucleo- 
Proteid—Bile Acids—Bile Pigments—-Cholesterin—Lecithin, ete.—Influence 
of Various Factors on the Secretion of Bile—Flow of Blood—Food— 
Pressure of other Organs—Nerves—Chemical Substances — General Con- 
clusions . : : : ; . : . : ; . . page 559 


THE CHEMISTRY OF THE URINE. 
By F. GOWLAND HOPKINS. 


Introductory—Quantitative Composition of Urine—Variations in its Amount and 
Specific Gravity—Its Chemical Reaction—The Nitrogenous Constituents : 
Total Nitrogen; Urea; Ammonia; Uric Acid; Xanthin Bases; Creatinin : 
Hippuric Acid; Amido-Acids—Proteids—The Aromatic Substances—The 
Carbohydrates—Glycuronic Acid and its Conjugated Compounds—Oxalie Acid 
—Acids and Oxyacids of the Fatty Series—Colour of the Urine and the 
Chemistry of its Pigments: The Preformed Pigments of Normal Urine; 
Chromogenic Substances ; The Pigmentation of Pathological Urine—The In- 
organic Constituents—General Characteristics of the Organic Urinary Com- 
pounds—Comparative Chemistry of the Urine : : : . page 570 


THE MECHANISM OF THE SECRETION OF URINE. 
By ERNEST H. STARLING. 
Theories of Urinary Secretion—Theory of Bowman—Theory of Ludwig—Secretion 
of Water—Methods—The Concentration of the Urine—Heidenhain’s Criticism 
of the Theory of Ludwig—Experiments of Nussbaum—Experiments of Ribbert 


—Experiments of Bradford—The Influence of the Nervous System on the 
Secretion of Urine . ; ; : , 4 : F : . page 639 


THE MECHANISM OF THE SECRETION OF MILK. 
By E. A. SCHAFER. 


General Considerations—Influence of the Nervous System—Action of Pilocarpine 
and Atropine—Influence of Diet—Place of Formation of the Organic Con- 


Mechanism of the Discharge of Milk : i ; : ; . page 662 


SECRETION AND ABSORPTION BY THE SKIN. 
By E. WAYMOUTH REID. 
Chemical Nature of Skin Secretions—The Secretion of Sweat—Electro-Motive 


Phenomena in Skin ai me by the Skin of Man—Of Lower 
Mammals—Of the Frog . : : : ; . page 669 


Xiv CONTENTS. 


CHEMISTRY OF RESPIRATION. 
By M. S. PEMBREY. 


Historical—Respiratory Changes in Air—Methods—Conditions affecting Respiratory 
Exchange—Cold - Blooded Animals—Fishes—Warm - Blooded Animals—In- 
fluence of External Temperature—Of Muscular Activity—Of Food—Of 
Size of Animal—Of Time of Day—Of Age— Respiration by Skin 
in Amphibia—In Mammals—Efiects of Varnishing Skin—Respiration in 
Alimentary Canal—Respiration of Fotus—Of Embryo—The Respiration of 
Different Gases—The Respiration of Vitiated Air—Asphyxia—Exchange of 
Gases between Blood and Air—Frequency of Respiration in Man—In Animals 
—Changes in Composition of Air—Effect of Respiration on Blood—Gases of 
Blood— Methods—Arterial and Venous Blood—Condition of Gases in Blood— - 
Causes of Gaseous Exchange between Blood and Air—Exchange of Gases 
between Blood and Tissues—Causes of such Exchange . : . page 692 


ANIMAL HEAT. 
By M. S. PEMBREY. 


Thermometry—Warm and Cold Blooded Animals—Temperature of Man and other 
Warm-Blooded Animals—Hibernation—Influence of Various Conditions upon 
Temperature—Time of Day—Age—Muscular Work—Mental Work—Food— 
Sleep—Seasons—Race—Menstruation and Pregnancy—Individual Peculiarities 
—Temperature of Surroundings—Extreme Heat and Cold—Baths—Drugs— 
Temperature of Different Parts of Body—Of Arterial and Venous Blood—Of 
the Skin—Regulation of Temperature—Heat Production—Historical—Relation 
to Chemical Changes—Specific Heat of Body—Seats of Heat Production— 
Measurement of Heat Production—Calorimetry—Respiratory Exchange as 
Measure of Heat Production—Heat Production in, Cold-Blooded Animals 
—Regulation of Heat Loss—Influence of Size of Body—Influence of Nervous 
System—Development of Power of Regulation—Temperature of Body after 
Death : : : ‘ : . : : : : : . page 785 


METABOLISM. 
By E. A. SCHAFER. 


Introductory—Balance of Nutrition—Composition of Foodstuffs — Heat Value of 
Foodstuffs — Necessary Amount of Proteid—Special Constituents of Diet— 
Their Effect on Metabolism—Gelatin—Carbohydrates—Fats—Inorganie Sub- 
stances—Metabolism in Inanition—With purely Proteid Diet—Relative Meta- 
bolic Activity of Tissues—Nitrogenous Metabolism—In Muscle—In the Liver 
__Effect of Muscular Activity on Proteid Metabolism—Metabolism of Carbo- 
hydrates—Glycogen Formation—Phloridzin Diabetes—Glycogenesis— Puncture 
Diabetes—Influence of Pancreas on Carbohydrate Metabolism—Metabolism of 
Fat—Source and Formation of Fat—Action of Liver on Metabolism of 
Fat . ; : . : . : : : : : : . page 868 


THE INFLUENCE OF THE DUCTLESS GLANDS UPON 
METABOLISM—INTERNAL SECRETIONS. 


By E. A. SCHAFER. 


Introductory—The Thyroid Gland—The Pituitary Body—-The Suprarenal Bodies 
—Influence of the Spleen on Metabolism . : : page 937 


INDEX OF SUBJECTS . ; - : : : ; : : ; . page 963 


InpEX oF AUTHORS ‘ : : . : : . page 999 


PLATES 


\é 


LIST OF ILLUSTRATIONS. 


I. PLATES. 


I., 11.—Spectra of haemoglobin, its compounds and derivatives (modified from 


Preyer, “ Die Blutkrystalle”). 


111.—Spectra of various colouring matters (from MacMunn, “ The Spectroscope 


in Medicine”). 
Solar spectrum, with Frauenhofer’s lines and millimetre scale. 
Fresh human bile. 


. Alcoholic extract of human bile. 
. Diluted solution of human bile treated with hydrochloric acid. 
. Bile treated with nitric acid, and the precipitate dissolved in boiling 


absolute alcohol. 


. Pig’s bile. 
. Ox or sheep bile. 
. Ox or sheep bile treated with nitric acid, and the precipitate dissolved 


in boiling alcohol. 


. Ox bile treated with hydrochloric acid, and the precipitate dissolved in 


boiling alcohol. 


. Guinea-pig’s bile. 

. Rabbit’s bile. 

. Mouse’s bile. 

. Crow’s bile. 

. Pettenkofer’s test on human bile salts. 


- pig’s bile salts. 


” 
. Band of urobilin in normal human urine. 
. Bands in urine of rheumatic fever; the urine treated with nitric acid. 


» 9) 3, With albuminuria; the urine treated with nitric acid. 


. Urine of same case treated with caustic potash. 
. Bands of hematin from ovarian cyst. 

. The same treated with a reducing agent. 

2. Spectrum of O2, after twenty-four hours. 


of ,, lutein, from peritoneal fluid. 
5 as ,, trom serum of dog’s blood. 


XVi 


by 


OMmAIKHDOR WN eS 


TEAST IOR ALL OSTRATIONS. 


II. FIGURES IN TEXT. 


. Crystals of phenylglucosazone 


Ss »» phenylmaltosazone 


. Lactose crystals (Frey) 

. Crystals of phenyllactosazone 

. Inosite crystals (Frey) 

. Cholesterin crystals (Frey) . 

. Leucine crystals (Kiihne) 

. Tyrosine crystals (Frey) 

. Crystals of egg albumin 

. Proteid erystals from human urine (eal and tocl Paton) 
. Crystallised vitellin of the oat kernel (Osborne) 

. Charcot’s crystals ‘ : 

. Creatine crystals (Kuhne) 

. Creatinine crystals (Kiihne) . ; 

. Creatine-zine chloride crystals (Kuhne) 

. Spherical compound of mercury and creatine (G. S. J dares 

. Compounds of xanthine and hypoxanthine, by means of which these aie 


stances may be isolated and identified (Kiihne) . 


. Zine sarcolactate (Kiihne) 

. Calcium sarcolactate (Kiihne) 

. Absorption spectra of retinal pigments (Kiihne) , 
. Oliver’s apparatus for estimating the number of blood pepe 


»  hemoglobinometer . 


- The eater raeber : 
. The heematoscope 
. Graphic representation of the ppecteats of Peeptegecl: ead ieee 


globin (Rollett) 


: Teanie slit employed in Vierordt’s poem of epechroiage aan y 
. Glass troughs for containing the liquids to be examined by the methods 


of “peinonas nae (Kriss) 


28. Trough mounted on stand, as used in spectro phabareeer (ce 

. Section of glass trough (ines) : 

. Spectrophotometer with absorption trough al ae 

. Hiifner’s spectrophotometer . 

2. Schematic representation of the ae8 ie ed by the rays bi light béfore 


entering the sht of the collimator of Hiifner’s spectrophotometer 
(Kriiss) 


3. The photographic spectrum aE eraeara ain om oxy viminoglates : 
. Graphic representation of the spectra of oxyhzemogloblin and hemoglobin 


(Rollett) 
5. The photographie spectrum of spaupadiah ots oad of CO- hsnosloene 
% ~ 5 oxyhemoglobin and methemoglobin 
Fo , hemin 
a _ 5 oxygenised lesthoelieeeeaeae and of peer 
chromogen 


. The photographic spectrum of emo perphy rin 
. Diagram to show the dilution of the blood produced in ae by the 


injection of dextrose (Leathes) 


. Diagram to show the influence of the ee enous cajectiaa of dextrose 


on the blood pressure in the abdominal viscera . 


. Diagram to show the effect of injecting dextrose after a prose 


Bleeding 


FIG. 
. Diagram to show effects of the injection of a lymphagogue of the first 


LIST OF ILLUSTRATIONS. 


class on the blood pressures in the abdominal organs 


. Diagram to indicate variations in pepsin after food (Griitzner) 
; Chart showing acidity of gastric juice after feeding with ee 


food 


. Chart of the course of secretion of pariereatic juice 

. Chart of the percentage composition of the flow of pancreatic juide 
. Showing influence of various foodstuffs upon the secretion of bile 
. Urea nitrate and oxalate crystals 

. Uric acid crystals 


” ” 


. Ammonium and aia urate 

. Creatinin and hippuric acid 

. Leucine and tyrosine 

. Cystine 

. Calcium oxalate : 

. Chart of spectra of urinary sslenneiiis 

. Stellar phosphates ; triple ee 

. Roy’s oncometer 

. Diagrammatic section canes Roy’s s sperm. 

. Roy’s oncograph : 

. Regnault and Reiset’s respiration pepeetas 

. Voit’s respiration apparatus 

. The respiration apparatus in the Physiological Daceatory, Oxford 
. Haldane’s respiration ae . 

. Lowy’s 


” 


. Fredericq’s curve of daily v. ae in the ayeaeian of — gen 
. Hutchinson’s spirometer 


. Pfliiger’s blood-pump : 

. Leonard Hill’s blood-pump . 

. Pfliiger’s lung catheter 

; Curves of dissociation of oxyhzemoglebin 
. Pfliiger’s aérotonometer 

. Fredericq’s 


. Bohr’s hemataérometer 
. Chart showing daily variation in temperature observed by Ringer and 


of} 


Stewart 


. Chart showing daily ae in “eye ebeeered by Ogle, 


Clifford Allbutt, Casey and Rattray, and Crombie 


. Chart showing daily variation in temperature observed by Ji ceeencen a 


Liebermeister 


. Curve of daily variation in the lenpamens of the urine . 
. Chart showing daily variations in temperature observed during U. Moxa’: s 


experiments 


. Diagram of ice calorimeter . 

; eee of Dulong’s water calorimeter 

. Diagram of air genes (Haldane, Hale White, ad iieetiboare) 

3 Monkey deprived of thyroid (Horsley) 

. Effect upon the blood pressure in the dog of ie ‘hteaar ore aeaten 


of decoction of thyroid 


. Tracing showing effect of pituitary ne upon heart: Bee and blood: 


pressure in the dog 


. Tracing showing effect of siedesel exec oe muscle contraction in 


the frog 
b 


XVill 


FIG. 


88. 


89. 
90. 


91. 


92. 


Tracing showing effect of suprarenal extra 


LIST OF ILLUSTRATIONS. 


ct upon heart-beats and blood- 


pressure in the dog; one vagus only cut 


The same with both vagi cut 


. . . 


Tracing showing effect of suprarenal extract upon heart, limbs, spleen, 
and blood-pressure, after section of cord and vagi : : 
Tracing showing effect of suprarenal extract upon blood-pressure and 


limb-volume : , 


A, Ergograph tracing of a person suffering from Addison’s disease. 5B, 


Tracing made from the same person a 
suprarenal extract (Langlois) 


fter six weeks’ treatment with 


PAGE 


952 
953 


954 


956 


958 


ties BOOK “OF PHYSIOLOGY. 


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TEXT-BOOK OF PHYSIOLOGY. 


THE CHEMICAL CONSTITUENTS OF THE BODY 
AND FOOD. 


By W. D. HALLrBuRTON. 


Contents :—The Carbohydrates, p. 2—The Fats, p. 17—Lecithin, p. 21—Choles- 
terin, p. 22—The Proteids, p. 24—Decomposition Products of Proteids, p, 28— 
Synthesis of Proteids, p. 35—Theories of Proteid Constitution, p. 383—General 
Properties and Reactions of Proteids, p. 39—Classification of Proteids, p. 49 — 
Vegetable Proteids, p. 51—Poisonous Proteids, p. 55 —Compound Proteids, p. 61 
—The Albuminoids, p. 69—Inorganic Compounds, p. 76. 


THE chemical constituents of the body are very numerous, and the 
majority of them are compounds of complicated structure. In the 
following article I propose to treat of these compounds, first in classes, 
and then individually, and in a subsequent chapter to discuss the various 
tissues and organs in their chemico-physiological aspects. 


In order to classify the chemical constituents of the body, one might 
proceed upon a purely chemical basis, beginning with the simplest and ending 
with the most complex compounds; or a purely physiological basis might be 
adopted, in which the compounds would be described in the order of their im- 
portance in the vital processes of the organism. But a compromise between these 
two exclusive methods is found to be that which is of most practical usefulness. 


We may, in the first place, divide the compounds found in the body 
into those of inorganic, or mineral nature; and those which are termed 
organic, or carbon compounds. 

The inorganic compounds present are water; various acids, such as 
the hydrochloric acid of the gastric juice; and numerous salts, such as 
calcium phosphate in bone, and sodium chloride in blood, urine, ete. 

The organic compounds are more numerous, and these we may 
conveniently group as follows :— 


( Proteids, e.g. albumin, myosin. 
Nirrocenous . + Albuminoids, e.g. gelatin, keratin. 
Simpler nitrogenous substances, e.g. lecithin, creatine. 
Fats. 
Non-NiTROGENOvs 4 Carbohydrates, e.g. sugar, starch. 
| Simpler organic substances, ¢.g. alcohols, lactic acid, 
VOL. IL—1I 


2 CHEMICAL CONSTITUENTS OF BODY AND OCP: 


The most useful classification of the more complex organic com- 
pounds is the time-honoured one, into proteids, carbohydrates, and 
fats. Taking this as our starting-point, we shall find that the other 
substances present may be described either in subsidiary classes to 
these, or as decomposition products of the more complex substances. 

The elements found in these compounds are carbon, hydrogen, 
nitrogen, oxygen, sulphur, phosphorus, chlorine, iodine, fluorine, silicon, 
sodium, potassium, calcium, magnesium, lithium, iron, and occasionally 
manganese, copper, and lead. 

It will be on the whole most convenient to study the organic 
compounds first, in the following order :-— 


1. Carbohydrates ; 
Fats, with which we shall study the lecithins and cholesterins ; 
3. Proteids and albuminoids. 


NS) 


In following out this plan we shall discuss some of the chemical 
constituents of the food as well as those of the body. 


THE CARBOHYDRATES. 


The carbohydrates are found chiefly in vegetable tissues, and many 
of them form important foods. Some, however, are found in or formed 
by the animal organism, such as glycogen or animal starch, dextrose, and 
lactose or milk-sugar. The carbohydrates may be conveniently but 
loosely defined as “compounds of carbon, hydrogen, and oxygen, the 
two last-named elements being in the proportion in which ‘they 
occur in water. But this definition, if pushed, would include several 
substances like inosite, acetic acid, and lactic acid, which are not 
carbohydrates. 

The work of Fischer Tollens? and many other cheinists has, 
moreover, shown that carbohydrates are not, as their name would 
imply, simply compounds of carbon with water, but their constitutional 
formula has been in many cases thoroughly worked out, and their 
composition shown to be much more complex. This work has culminated 
in the synthetical production of many of the sugars. 

From the chemical standpoint, the sugars (which are the simplest 
of the carbohydrates) may be divided into two classes— 

1. Those which, when digested with dilute acids, do not yield any 
other sugar or sugars; this class includes the elucoses ; and 

2. Those which, when so treated, do yield some other sugar or sugars ; 
this class includes the members of the cane- -sugar group. 

Further, the sugars are designated according to the number of 
carbon atoms they contain; thus we have trioses (e.g. glycerose), tetroses 
(eg. erythrose), pentoses (e.g. arabinose, xylose, rhamnose), hexoses (¢.9. 
glucose, mannose), heptoses, octoses, and nonoses, according as they 
contain, three, four, five, six, seven, eight, and nine atoms of carbon 
respectively in their molecules. 

The great majority of these sugars possess, however, but little 


' See especially E. Fischer, Ber. d. deutsch. chem. Geselisch., Berlin, Bd. xxiii. S. 2114. 
* Tollens, ‘‘ Kurzes Handbuch der Kohlenhydrate,” Breslau. 


THE CARBOHYDRATES. z 


physiological interest, and their chemical relationships and reactions 
will be found described in works on chemistry.! 

Those which are of physiological importance are the hexoses and 
their derivatives. Nearly all the carbohydrates with which we have 
to deal in the animal body contain either six carbon atoms, or some 
multiple of six. The same is true of those which are used as food. The 
remainder are either synthetical products of the chemical laboratory, or 
more or less rare products of the vegetable world. 


But to this rule there is one exception; the pentoses do possess some 
physiological importance. When Hammarsten? was investigating the nucleo- 
proteid material he separated from the pancreas, he found that by boiling it 
with dilute mineral acid he obtained a reducing substance. This formation 
of a reducing sugar-like substance from nuclein is not unique, as Kossel * and 
his pupils have obtained a similar product from yeast-nuclein. The sugar, 
however, does not ferment with yeast, but, like the pentoses, gives a red 
coloration with phloroglucinol and hydrochloric acid, and by distillation with 
hydrochloric acid yields furfuraldehyde. An osazone is obtainable from it 
in the form of fine rosettes of crystals, melting at 158° to 160° C., and these 
appear to be identical with those prepared from pentoses by E. Salkowski 
and M. Jastrowitz.+ 

The physiological action of pentoses was investigated by W. Ebstein.® 
When xylose or arabinose, dissolved in water or coffee, are taken with the 
food, they rapidly appear in the urine; they are not assimilated. The use of 
fruits, such as pears, that contain pentosanes, the mother substances of pentoses, 
may lead to the appearance of the latter substances in the urine. It is 
of course important not to confound such a temporary condition with diabetes. 

Max Cremer ® has investigated the physiological action of some of the rare 
sugars, especially their influence on the formation of glycogen. He found that 
in rabbits mannose increases the hepatic glycogen, and that, though the 
pentoses readily pass into the urine, a small quantity is assimilated as glycogen. 
Lindeman and May? have confirmed Cremer’s results. 

Salkowski® has investigated a large number of diabetic urines, but was 
unable to find pentose in any of them. Nevertheless, he found pentose in 
various other morbid conditions in the urine, in which their presence could 
not be attributed to diet. He suggests that in these cases they originate in 
the body from such nucleo-proteids as Hammarsten found in the pancreas, the 
processes of oxidation being lessened so that they were not broken up into 
simpler materials. 


We can now proceed to the study of the carbohydrates concerning 
which we have more accurate physiological knowledge; and these may 
be classified into the following three groups :— 


1 See article ‘‘ Sugars,’’ Watts’s ‘‘ Dictionary of Chemistry,” London, 1894, vol. iv. 

2 Zischr. f. physiol. Chem., Strassburg, Bd. xix. S. 19. 

° Kossel and Neumann, Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. xxvii. S. 2215. 

4 Centralbl. f.d. med. Wissensch., Berlin, 1892. Nos. 19 and 32. Blumenthal (Berl. Klin. 
Wehnschr., 1897, Bd. xxxiv. S. 245) has obtained pentoses from numerous other nucleo- 
proteids. 

5 Virchow’s Archiv, Bde. exxix. S. 401; exxxii. S. 368; exxxiy. S. 361. 

6 Ztschr. f. Biol., Miinchen, Bd. xxix. S. 484. 

7 Chem, Centr.-Bl., Leipzig, 1896, Bd. i. S. 932. 

8 Berl. klin. Wehnsehr., Bd. xxxii. S. 364. See also Kiilz and Vogel (Ztschr. f. Biol., 
Miinchen, 1895, Bd. xxxii. S. 185). These observers found pentoses in only four out of 
sixty-four cases of human diabetes. But they are generally found in the severe forms of 
diabetes produced in dogs by the extirpation of the pancreas or by administration of 


phloridzin. 


4 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


1, Monosaccharides (C,;H,,0,).—The most important members of this 
group are: 
Dextrose. Galactose. 
Levulose. Mannose. 
2. Disaecharides (C,,H,,0,,).—The most important members of this 
group are: 
Cane Sugar. Maltose. 
Lactose. Isomaltose. 
3. Polysaccharides (C,H, 0;),—The most important members of this 
group are: 


Starch. | Cellulose. 

Glycogen. Tunicin. 

Dextrins. Gums. 
Inulin. 


The monosaccharides.—When an alcohol is oxidised, the first 
stage in oxidation is the formation of an aldehyde, or a ketone; if 
oxidation of the aldehyde is continued, an acid is formed. 

When more complicated alcohols are oxidised, similar products result. 
The monosaccharides are the first oxidation products of the hexatomic 
alcohols (CH,.OH—(CH.OH),—CH,OH). 

Of the hexatomic alcohols, three are known, namely sorbite, mannite, 
and dulcite. 

Dextrose is the aldehyde of sorbite.’ 
Mannose _,, : mannite. 
Galactose _,, . duleite. 

Levulose ,, ketone of mannite. 


Sugars of the monosaccharide group may thus be either aldehydes, 
when they are called aldoses; or ketones, when they are called ketoses, 

Dextrose, mannose, and galactose are aldoses, and have the structure 
represented by the following formula :— 


CH,.OH—(CHOH),—CHO 


They differ from one another in their stereochemical formule. 
Levulose is a ketose, and has the structure represented by— 


CH, 0H—(CH.0.),—CO=Cai0m 


The difference between the aldoses and ketoses is shown by oxidation, 
levulose, like all ketoses, yielding acids which are poorer in carbon. 

If chlorine or bromine water is used as the oxidising agent, the 
aldoses (dextrose, mannose, and galactose) give isomeric monobasic acids 


of the formula— 
CH,.0H—(CH.OH),—COOH ; 


and then, by further oxidation by means of nitrie acid, yield dibasic 
acids of the formula— 


COOH—(CH.OH),—COOH 


Both sets of acids are stereo-isomerides. 


Monobasic acid. Dibasic acid. 
From Dextrose . . Gluconie acid Saccharie acid. 
» Mannose . . Mannoniec acid Manosaccharic acid. 
», Galactose . . Galactonic acid Mucie acid. 


‘Meunier, Compt. rend. Acad. d. sc., Paris, tome cxi. p. 49; Vincent and Delachanal, 
ibid., p. 51. 


THE MONOSACCHARIDES 5 


Glycuronie acid.—-If saccharic acid is heated five or six hours in the 
water bath, it is changed into saccharo-lactonie acid, C,H,O;. If this is 
reduced by means of sodium amalgam, one obtains glycwronie acid ;* this 
substance is of considerable interest because it is sometimes found in the 
body, and when it passes into the urine is apt to be mistaken for sugar, 
many of the tests for which it gives. 

Its composition is— 


COOH—(CH.OH),—CHO = C,H,,0, 


It is soluble in water and alcohol, is dextro-rotatory, reduces alkaline 
solutions of metallic salts, and yields saccharic acid on oxidation with 
bromine. It does not undergo the alcoholic fermentation. Though 
related in its composition so nearly to the carbohydrates, it yields with 
urea decomposition products which are aromatic, such as orthonitro- 
benzyl alcohol (Jaffe).2 It occurs in the urine in the form of the 
potassium salt (C,;H,O,K) after the administration of chloral and 
butylehloral,? nitrobenzol,t orthonitrotoluol? camphor,’ ete. — It also 
occurs in the urine after chloroform narcosis, and in the paralytic 
secretion that takes place on section of the renal nerves.’ Occasion- 
ally it is found without any apparent cause, as a result of disordered 
metabolism. 

Levulose on oxidation always yields acids containing less carbon 
atoms than itself, namely, trioxybutyrie (CH,OH(CH.OH),COOH), 
formic (H.COOH), and glycollic (CH,OH.COOH) acids. But different 
acids are yielded by different methods of oxidation; thus chlorine or 
bromine and silver oxide oxidise levulose to glycollic acid;* nitric acid 
yields oxalic, tartaric, glycollic, acetic, and other acids.’ 


Synthesis of sugars.—The first step towards the synthesis of the sugars 
was made by Butlerow.'? He obtained a sugar-like substance by adding lime 
water to a solution of dioxymethylene; this he termed methylenitan, 
and gave its formula as C-H,,0; Loew! next obtained a condensation 
product of formaldehyde (CH,O) by means of lime water; to this substance 
he attributed the formula (C,H,,0,), and called it formose. 

Neither methylenitan nor formose ferment with yeast. Fischer” 
investigated these substances, and found that they were mixtures of two 
sugars, one of which is formose (C,H,,0,), and another a-acrose #8 (C;H,,0,), 
both of which yield crystalline osazones. 

From the osazone which is yielded by a-acrose the sugar can be again 


1H. Thierfelder, Ztschr. f. physiol. Chem., Strassburg, 1887, Bd. xi. S. 388; 1891, Bd. xv. 
S. 71; Ber. d. deutsch. chem. Gesellsch., Berlin, 1886, Bd. xix. S. 8148; E. Fischer and 
O. Piloty, ibid., 1891, Bd. xxiv. S. 521. 

2 Zischr. f. physiol. Chem., Strassburg, Bd. ii. S. 47. 

3 Musculus and y. Mering, Arch. f. d. ges. Physiol., Bonn, Bd. xx. 8. 64. 

+y. Mering, Centralbl. f. d. med. Wissensch., Berlin, 1875, No. 55. 

° Jaffe, Zoc. cit. 

§ Schmiedeberg and Meyer, Ztschr. f. physiol. Chem., Strassburg, Bd. iii. S. 422. 

7 Ashdown, Brit. Med. Journ., London, 1890, vol. i. p. 171. 
f eaaawet and Habermann, Ann. d. Chem., Leipzig, Bd. elv. ; Kiliani, iid., Bd. 
celv. S. 175. 

9 Kiliani, ibid., S. 162; Hornemann. Journ. f. prakt. Chem., Leipzig, Bd. Ixxxix. S. 283. 

1 Ann. d. Chem., Leipzig, Bd. exx. S. 295 ; Compt. rend. Acad. d. sc., Paris, tome lii. 
p- 145. 

U Journ. f. prakt. Chem., Leipzig, Bd. xxxiii. 8. 321. 

2 Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. xix. 8. 2133. 

13 Acrose is a sugar obtained by Fischer, ibid., Bd. xx. S. 1093 and 2566, by acting on 
acrolein bromide with bases (2C,H,OBr,+(2Ba(OH),=C,H,,0,+2BaBr,; two isomeric 
sugars, «- aud £-acrose are thus produced, 


6 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


obtained by reduction through the intermediate osone (see p. 9). The sugar 
obtained is identical with levulose or fructose, except that it is optically inactive. 
If this inactive levulose (7-levulose) is submitted to the action of yeast, the 
levorotatory constituent (d-levulose) ferments, and the residue is dextro- 
rotatory. This is /-levulose,! but it is not the natural sugar. The natural 
sugar was formed in the following way :—a-acrose was reduced to the corre- 
sponding alcohol, a-acrite, which is identical with 7-mannite; from this the 
sugar 7-mannose was obtained, which was fermented, and /-mannose alone 
remained. By further oxidation ¢-mannose yields ¢mannonic acid. By 
fractional crystallisation of the morphine or strychnine salt of this acid, it can 
be separated into its two active (@ and /) constituents, and from these the 
corresponding sugars (mannoses) are obtained by reduction, and these by 
means of the ozones into the corresponding levuloses, the d-levulose being 
the levorotatory natural sugar. 

In order to get dextrose, the d- and /-mannonic acids are heated with 
quinoline ; this partly decomposes these acids, yielding d- and /-gluconie acids, 
and by reduction of these acids the sugars d-glucose (or dextrose) and /-glucose 
are obtained. 


Of the numerous sugars in the monosaccharide group, dextrose, 
levulose, and galactose possess special physiological interest. 

Dextrose is found widely distributed in nature in grapes, and many 
other fruits; also in seeds and roots, and in honey. It is generally 
mixed with levulose. In the animal body it is the final result of the 
digestion of starch, and occurs in small quantities in the blood and 
lymph; traces only occur in normal urine. The quantity both in the 
blood and urine is increased in diabetes. It erystallises either in fine 
needles, free from water of crystallisation, or with 1 molecule of water of 
crystallisation in small plates; these melt at 100° and lose their water 
at 110° C. The water-free crystals melt at 146° and at 170° C. lose 
water, the residue being glucosane (C,H,,O;). By higher temperatures 
it is converted into caramel. 

Dextrose is readily soluble in water; the solution is not so sweet as 
one of cane-sugar; it is dextrorotatory. The specific rotation? varies 
with temperature and concentration, but at 20° C. averages +52°°6. 
A freshly-made solution may have nearly double this rotatory power, 
but on standing for some time, or on heating the solution, the rotation 
becomes normal. Dextrose is slightly soluble in cold, very soluble in 
hot alcohol. It is insoluble in ether. 

Levulose is found with dextrose in the vegetable kingdom, and in 
honey. It is formed by the hydrolytic splitting of cane-sugar and other 
carbohydrates, but is obtainable with special ease from inulin. It is 
occasionally found in diabetic urine.* In many cases of diabetes it may 
be used with impunity in the food. 


1 The /, 7, and d are prefixes primarily attached to isomeric sugars, to indicate their action 
on polarised light, which is due to the presence and position of an asymmetric carbon atom. 
The terms were introduced by Fischer to denote this character, but they have been extended 
to comprise derivatives of the original sugar, which derivatives may have the opposite 
rotatory power, as is seen in the above example, where a d sugar is levo- and an Z sugar is 
dextrorotatory. 

* The specific rotation (z)p of any substance is the amount of rotation in degrees of a 
circle of the plane of polarised light, produced by 1 grm. of the substance dissolved in 
lc.e. of liquid, examined in a tube 1 decimetre long. It is measured for yellow (sodium) 
light. 

3 Leo (Virchow’s Archiv, 1887, Bd. evii. S. 108) has found as an occasional constituent 
of diabetic urine, a levorotatory sugar which is not levulose. Its reducing power is small, 


REACTIONS OF THE MONOSACCHARIDES. 7 


Its crystals, which are difficult to obtain, are partly water-free 
(C,H,.0,) and partly contain water of crystallisation (2C,H,,0,.H,O). 
Levulose is different in chemical constitution from the other sugars we 
have studied in this group. It, however, gives the same general tests ; 
but its specific rotatory power has not been satisfactorily determined. 

Galactose is obtained by the hydrolytic decomposition of lactose or 
milk-sugar, and from many other carbohydrates, especially gums and 
mucilages. It is obtained by the decomposition of a glucoside occurring 
in the brain called cerebrin.! It crystallises in needles or plates, which 
melt at 168° C. It is somewhat more difficult of solution in water than 
dextrose, and more strongly dextrorotatory. 


Mannose or seminose is another monosaccharide which is of scientific 
interest, as it is the aldehyde of the alcohol (mannite) of which levulose is the 
corresponding ketone. 

It does not occur free in nature. It is obtained from mannite by 
oxidation,” and also by the action of dilute sulphuric acid on the so-called 
reserve cellulose.* 


Reactions of the monosaccharides.—(a) Fermentation—They are 
directly fermentable by yeast into alcohol and carbonic acid (C,H,,0, 
= 2C,H;.0H+2CO,); and by the Bacterium lactis into lactic acid (C,H,,0, 
= 2CH,—CH.OH.—COOH). But this property of fermentation is only 
possessed by those which occur in nature. 

(b) Reducing power.—Being aldehydes or ketones, they are easily 
oxidisable, and reduce metallic oxides in alkaline media. 


They cause a deposition of metallic silver in an ammoniacal silver solution 
containing some caustic soda; and of metallic bismuth from basic bismuth 
‘nitrate suspended in soda (Bottcher’s test) ; and of the red cuprous oxide (Cu,0), 
or of the yellow cuprous hydrate Cu(OH,), from an alkaline solution of cupric 
oxide, as in Trommer’s and Fehling’s tests.* 


(c) When heated in the dry state, before they char, they yield a 
brownish product called caramel. A similar substance is formed by 
boiling with alkalies (Moore's test)? In the brown substance formed, 
among other bodies is levulinic acid, CH,—CO—CH,—CH,—COOH. 


its rotatory power weak («p-26); it forms an osazone. Neubauer and Vogel 
(‘‘ Anleitung zur qualitativen und quantitativen Analyse des Harns,” 1890) suggest the name 
*“laiose”’ for it. 

1 Thierfelder, Zitschr. f. physiol. Chem., Strassburg, Bd. xiv. S. 209; Brown and 
Morris, Proc. Chem. Soc., London, 1889, p. 167. 

? Fischer and Hirschberger, Ber. d. deutsch. chem. Gesellsch., Berlin, Bde. xxi. S. 1805 ; 
‘xxii. §. 1155 and 3218. 3 Reiss, thid., Bd. xxii. S. 909 and 3218. 

4In Allihn’s method (Journ. f. prakt. Chem., Leipzig, Bd. xxii. S. 55) of estimating 
the reducing power of a sugar, the cuprous oxide obtained by Fehling’s method is collected 
and weighed as metallic copper. Pifliiger (Arch. f. d. ges. Physiol., Bonn, 1877, Bd. lxvi.) 
recommends that the cuprous oxide should be dried at 120° and weighed. O'Sullivan and 
Stern (Journ. Chem. Soc., London, 1896, p. 1691), who have recently prepared dextrose 
from several sources, have found that 1 gr. of CuO is reduced by 0°4535 gr. of dextrose 
(1 gr. Cu,O=0°5045 gr. dextrose). On the relation between reducing power and specific 
rotation see a series of papers by H. T. Brown, G. H. Harris, and J. H. Millar (Proc. 
Chem. Soc., London, 1896, pp. 241-244). If the reducing power of dextrose is taken as 
100, that of levulose is 92 to 94 (ibid., 1897, p. 4). 

°F. Framm (Arch. f. d. ges. Physiol., Bonn, 1896, Bd. Ixiv. S. 575) has found that 
Moore’s test is accompanied by the formation of products of oxidation, namely aldehyde 
and formic acid. 


8 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


(d) Phenylhydrazine test—This is carried out in the following 
way :— 


To 5c.c. of a solution of sugar (which should not be stronger than 0°5 per 
cent.) 1 decigramme of phenylhydrazine hydrochloride and 2 decigrammes of 
sodium acetate are added, and the mixture heated on the water bath for 
half an hour. On cooling, if not before, a crystalline or amorphous pre- 
cipitate separates out. If amorphous it may be dissolved in hot aleohol, 
the mixture diluted with water, and boiled to expel the alcohol, whereupon 


Fic. 1—Crystals of phenylglucosazone. 


the compound or osazone separates out in yellow crystals. It is important. 
that there should be an excess of phenylhydrazine. 


Dextrose gives a precipitate of phenylglucosazone (C,,H..N,0,), 
which crystallises in yellow needles (melting-point 205° C.). Levulose 
and mannose yield osazones identical with this. 

Galactose yields a very similar osazone (phenylgalactosazone). It 
differs from phenylglucosazone by melting at 190—193° C., and in being 
optically inactive when dissolved in glacial acetic acid. 

The chemistry of the reaction is represented in the following 
equations :— 


THE DISACCHARIDES. 9 


1. CH,OH[CH(OH) },CH(OH)COH + H,N.NH(C,H,) 
(dextrose) (phenylhydrazine) 
poe JOH[CH(OH)], CH(OH)CH 
+H,0 
N—NH(C,H;) 
(hydrazone) (water) 
2. CH,OH[CH(OH)],CH(OH)CH 
I + C,H, NH—NH, 


—_NH(C,H,) 
(hydrazone) (phenylhydrazine) 
CH,OH[CH(OH) }|,C—CH 
- ll | +H, +H,0 
C,H,NH—N N—NH.C,H, 
(osazone) (hydrogen) (water) 


The hydrogen seen in the second equation is not really set free, but 
it is used to split up a further molecule of phenylhydrazine into aniline and 
ammonia (NH,—NH.C,H, + H, =NH,C,H, + NH,). 


In order to obtain the sugar from the osazone again, it is first 
treated with fuming hydrochloric acid.t This gives rise to phenylhy- 
drazine and a so-called osone. An osone is a substance which, besides 
the ketone group, contains an aldehyde group as well: CH,OH—(CH.OH), 
—CO—COH. 


By means of zinc and acetic acid the osone is easily reduced to sugar. 


Glucosamine.—A derivative of glucose which is of some physiological 
interest is amido-glucose or glucosamine, C,H,,0;.NH,. This is obtained on 
the decomposition of chitin and chondroitin. By treatment with nitrous acid 
it passes into dextrose— 


C,H,,0;-NH, +NOOH=C,H,,0,+N,+H,0 


Glucosamine can also be obtained by treating phenylglucosazone directly with 
reducing agents— 
C,H,,0,-(N,H.C,H.).+ H,O+ H, = C,H,,0,.NH,+ 
(phenylglucosazone) (glucosamine) 


NH,—NH.C,H, + NH,C,H, 
(phenylhydrazine) (aniline) 


This shows us another way of regenerating the sugars from their osazones.? 
Further particulars about glucosamine will be found in connection with chitin 
and cartilage. 


The disaccharides.—A disaccharide is a condensation product of 
two molecules of the simple sugars or monosaccharides, the change being 
attended with the loss of a molecule of water :— 


C5H,,05 + C5H,,05= C,,H,0;, + HO 
Thus— 
Cane-sugar is derivable from dextrose and levulose ; 
Milk-sugar, or lactose, from dextrose and galactose ; 
Maltose, from dextrose and dextrose. 


The general properties of these sugars are like those of the monosac- 


1K. Fischer, Ber. d. deutsch. chem. Gesellsch., Berlin, 1888, Bd. xxi. S. 2631; 1889, 
Bd. xxii. S. 87; 1890, Bad. xxiii. S. 2118. 

2 E. Fischer, ibid., Berlin, Bd. xix. S. 1920; Fischer and J. Tafel, ibid., Bad. 
xx. S. 2569. 


1eo CHEMICAL CONSTITUENTS OF BODY AND FOOD: 


charides; their solubilities are similar; they are optically active, 
erystallisable, diffusible, and sweet. Heated dry, they give rise to 
caramel. Further, they (with the exception of cane-sugar) reduce 
alkaline solutions of metallic oxides like Fehling’s solution, and (again 
with the exception of cane-sugar) form cr ystalline osazones. 

By hydrolysing agencies they take up water, and split into the simple 
sugars of which they are made up. Thus— 


Cane-sugar + water = dextrose + levulose. 
Maltose + water = dextrose + dextrose. 
Lactose + water = dextrose + galactose. 


Among the agents capable of producing this decomposition the 
inverting ferment of the small intestine must be particularly mentioned. 
The term inversion arose from the fact that, if cane-sugar is the sub- 
stance acted on, the previously dextrorotatory solution becomes levo- 
rotatory, because the levorotatory power of the levulose is greater than 
the dextrorotatory power of the dextrose formed. The term inversion 
has, however, been extended to include the similar decompositions of 
lactose and maltose. The reverse action by which the monosaccharides 
are united to form disaccharides is called reversion. 

Cane-sugar is generally distributed throughout the vegetable 
kingdom in the juices of plants and fruits, especially the sugar-cane, 
beetroot, mallow, and sugar-maple. As a food it is of high value. After 
abundant ingestion of cane-sugar, traces may be found in the blood and 
urine; but “the greater part undergoes inversion in the alimentary 
canal. 

It is readily soluble in water (100 parts of saturated solution contain 
67 of sugar)! but soluble with difficulty im alcohol. It forms large, 
colourless monoclinic crystals. It is strongly dextrorotatory, and 
the amount of rotation does not vary so much with concentration 
and temperature as do most of the other sugars. The average value 
of (a), =+66°5. 

Cane-sugar does not give many of the sugar tests; thus, it does not 
give Moore’s test; with Trommer’s test, it gives a blue solution, but no 
reduction occurs on heating. It does not react with phenylhydrazine, 
and it is not directly fermentable by yeast; the yeast, however, secretes 
an inverting ferment, and after inversion the glucoses formed are con- 
verted into alcohol and carbonic acid. 

By boiling with concentrated hydrochloric acid a deep red solution 
is formed. Dextrose, maltose, and lactose do not give this reaction. 

Maltose is one of the end products of the action of malt diastase on 
starch. It is also the chief sugar formed from starch by the diastatic 
ferments contained in the saliva and pancreatic juice. It is an inter- 
mediate product in the action of sulphuric acid on starch. It erystallises 
with one molecule of water of crystallisation in fine white needles. It 
is easily soluble in water and in alcohol; insoluble in ether. It is 
dextrorotatory; but its rotatory power decreases with concentration 
. (relatively) and with rise of temperature. 

For a 20 per cent. solution at 15° C. («),=+139°3. The amount 
of rotation is about 18° less for a freshly prepared solution than for one 
which has stood for some hours.” 


1 Scheibler, see Tollen’s ‘‘ Handbuch.” 
* Brown, Morris, and Millar (Proc. Chem. Soc., London, 1896, p. 244) give (z)p= +188". 


THE DISACCHARIDES. II 


Maltose reduces copper, bismuth, and other metallic salts in alkaline 
solutions, but its reducing power as measured by Fehling’s solution is 
about one-third less than that of dextrose.! It does not reduce Barfoed’s 
reagent? as dextrose does. It ferments readily with yeast. With 
phenylhydrazine, phenylmaltosazone is formed (C,,H,,N,O,); this erystal- 
lises in yellow needles much broader than those yielded by dextrose or 
lactose; it melts at 206° C. Unlike phenylglucosazone, it dissolves 
in seventy-five parts of boiling water, and is still more soluble in hot 
alcohol (Fig. 2). 


Fic. 2.—Crystals of phenylmaltosazone. 


Tsomaltose*® is a sugar formed at the same time as maltose by the 
action of either diastase, ptyalin, or amylopsin# on starch. It is also an 


1 Ten c.c. of Fehling solution corresponds to 0°05 grmns. of dextrose, levulose, or galactose, 
and to 0:07196 of maltose. 

213°3 grms. of cupric acetate are dissolved in 200 c.c. of water; to this solution, 
6 c.c. of acetic acid containing 38 per cent. of glacial acetic acid are added (Barfoed, 
**Organic Analysis,” p. 254). 

? Originally described by Fischer, Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. xxiii. 
S. 3687. Fischer’s observations, which have been called in question by some chemists, have 
been very generally confirmed. In his most recent paper on the subject, ibid., 1896, Bd. 
xxvii. S. 3024, he shows that isomaltose is not directly fermentable by yeast, and so may be 
separated from maltose. Its osazone is soluble in four parts of hot water, while that from 
maltose requires seventy-five parts. 

4 Kiilz and Vogel, Ztschr. f. Biol., Miinchen, Bd. xxxi. 


12, CHEMICAL CONSTITUENTS OF BODY AND FOOD: 


intermediate product in the formation of dextrose by mineral acids from 
starch. An amylolytic ferment in blood serum, capable of forming 
dextrose from starch, acts similarly.t A small quantity occurs in 
normal urine.2 It is readily soluble in water, is very sweet, and 
ferments slowly with yeast. Its general characters are like those of 
maltose, but its osazone forms fine yellow needles which melt at 150° C. 

Lactose or milk-sugar occurs only in milk, and occasionally in the 
first days of lactation in the ure in small quantities. 

It crystallises in rhombic prisms, which contain one molecule of water 
of crystallisation (Fig. 3). It is soluble in six 
parts of cold, and two and a half parts of hot 
water; it is therefore less soluble than the 
other sugars. It has only a faint sweet 
taste. Aqueous solutions are dextro-rotatory 
(a), = 59°3 (Hesse)* and +52°°5 for the 
hydrate at 20° C. (Schmoger).> Its reducing 
power as tested by Fehling’s solution is 

Ve intermediate between that of dextrose and 

maltose. Lactose is very resistant to the 

Fic. 3.—Lactose crystals.—After jnverting ferment of yeast, and so undergoes 

saeys the alcoholic fermentation very slowly. It 

is, however, rapidly inverted by the Kephir fungus, and of all the 

sugars is that most readily affected by the B. lactis; the lactic acid 
fermentation occurs in two stages, as follow :— 


1. 'C),H,,0;, +H,0 =4C, 2G: 


(lactose) (lactic acid) 


2. 20,H,0, = C,H.G,*-2C0,--9me 
(lactic acid) (butyric acid) 


With phenylhydrazine, lactose yields phenyl-lactosazone, which readily 
crystallises in needles (Fig 4). It is soluble in eighty to ninety parts 
of boiling water. Its melting point is 200° C. 


Among the rarer disaccharides must be mentioned frehalose (from certain 
fungi), and melebiose, a saccharose which with d-fructose (levulose) is obtained 
from raftinose. afinose™ is an interesting sugar found in Eucalyptus manna, 
cotton seeds, and barley. It is a trisaccharide, consisting of a combination 
of dextrose, levulose, and galactose. 


The polysaccharides.—To this group belong a large number of 
carbohydrates of high molecular weight, and with the formula (C,H,,0;),- 
Their molecular weights differ a good deal, but have not yet been 
determined directly by chemical methods.8 They are not crystalline, 
are indiffusible, and, as a rule, insoluble in cold water. In hot water 
they partially dissolve, forming opalescent solutions. Like the proteids, 


1 Rohmann, Centralbl. f. d. med. Wissensch., Berlin, 1893, 8. 849. 

* Lemaire, Ztschr. f. physiol. Chem., Strassburg, 1896, Bd. xxi. S. 442. 

* The most recent observations on lactose in the urine of women after childbirth are by 
Lemaire, Zéschr. f. physiol. Chem., Strassburg, 1896, Bd. xxi. 8. 442. Pavy, Lancet, London, 
1897, vol. i. p.1075. See also Hofmeister, Ztschr. f. physiol. Chem., Strassburg, Bd. i. S. 101. 

4 Ann. d. Chem., Leipzig, 1875, Bd. elxxvi. 8. 98. ’ 

> Ber. d. deutsch. chem. Geselisch., Berlin, 1880, Bd. xiii. S. 1922. 

° Ten c.c. of Fehling’s solution=0°06334 lactose ; see footnote 1, p. 11. 

‘ Loiseau, Compt. rend. Acad. d. sc., Paris, 1876, tome lxxxii. p- 1058 ; Ber. d. deutsch. 
chem. Gesellsch., Berlin, Bd. ix. S. 732; Scheibler, ibid., 1886, Bd. xix. S. 2868. 

® By Raoult’s method of determining the lowering of the freezing point in very dilute 
solutions, Brown and Motris (Journ. Chem. Soc., London, 1888, p- 610), have provisionally 


THE POLYSACCHARIDES. 13 


they are precipitated from their solutions by saturation with certain 
neutral salts, such as ammonium sulphate.! 


Fic. 4.—Crystals of phenyl-lactosazone. 


By hydrolysis they are finally split up into simple sugars; various 
dextrins and disaccharides being intermediate products. The dextrins 
are of various kinds, and are differently named by different observers. 
The reaction cannot be represented by equations with certainty as long 
as the molecular weights of the members of the group are unknown. 


Brown and Morris suggest the following series, indicating the successive 
steps of the hydrolysis, in the case of starch under the influence of diastatic 
ferments :— 


(C,H,)9;), + H,O = (Cy, Hossa + Crate n 


(starch) (dextrin) (maltose) 
(C, 5H,,0; ronan lel O=(C, pH )05)n—4 + C,,H,.01, 
(dextrin) (dextrin) (maltose) 
(C,H,,05)n—4 + HO = (C,H, ,0;)n_¢ + Cy2H2.01, 
(dextrin) (dextrin) (maltose) 


assigned to dextrin and soluble starch the formule (C,H,,0;),. and (C,H,,0;)5, re- 
spectively. The same method applied to starch, though not so satisfactorily, points toa 
molecular weight of between 20,000 and 30,000 ; that i is, “about three times greater than that 
of soluble starch. Sabanejeff, Chem. Centr.-Bl.. , Leipzig, 1891, 8S. 10 ; Journ. Russian Chem. 
Soc., vol. xxi. p. 515, by the same method assigns to glycogen the formula (Oe AO ame 

Y Pohl, Ztschr. f. phi ystol. Chem., Strassburg, Bd. xiv. S. 151; Young, ‘‘ Proc. Physiol. 
Soc.,” Feb. 13, 1897, in Journ. Physiol., Cambridge and London, vol, xxi. 


14 CHEMICAL CONSTITUENTS OF BODY AND HOOD, 


and so on, until at last we get to 


(C5H)995)4 + H20 = (CoH, 05)2 + CygHo,0y, 


(dextrin) (dextrin) (maltose) 
and finally 
(C,H, )9;)2 + H,O = C,.H..0,, . 
(dextrin) (maltose) 


The principal sub-groups of the polysaccharides are the starch 
group, the gum group, and the cellulose group. The starch group 
includes starch, inulin, lichenin, and glycogen. The gum group includes 
the dextrins, the plant gums and mucilages, and animal gum. The 
cellulose group includes cellulose, the hemicelluloses, and tunicin. 

Starch is one of the most widely distributed carbohydrates in the: 
vegetable kingdom. It occurs in nature in granules, which consist of 
two principal ‘substances, : starch-granulose and starch-cellulose ; of these 
the former only is dissolved by the digestive juices. Erythrogranulose, 
which gives a red colour with iodine, is present in small quantities 
(Briicke). 

Starch is insoluble in cold water, in alcohol, and in ether. With 
hot water it swells, forming an opalescent solution or starch paste. 
This, if concentrated, celatinises on cooling. On hydrolysis it forms 
first soluble starch (also called amylodextrin or amidulin), then other 
dextrins, and finally maltose and dextrose. 

The most characteristic reaction of starch is the blue compound it 
forms with iodine! It does not give Trommer’s test or Moore’s 
test, nor does it ferment with yeast. The specific rotatory power? 
of soluble starch for concentrations of 2°5 to 45 per cent. at 15°°5 C., 
(«)p = + 202°. 

Inulin is found in the roots of many composites. It is usually 
prepared from dahlias. It is the only polysaccharide which can be 
obtained in a crystallised form, namely, as sphero-crystals which 
polarise light. It is readily soluble in warm water; by cooling the 
solution it 1s precipitated. By hy drolysis its final product i is levulose. 

Lichenin is a polysaccharide occurring in Iceland moss, and certain 
alge. It is insoluble in cold water, soluble in hot water, gives a yellow 
colour with iodine, is converted into glucose by hot dilute mineral acids, 
but is not affected by saliva or pancreatic juice.* 

Glycogen.—This is a small but constant constituent of protoplasm, 
and of animal tissues generally. It is found in white blood corpuscles, 
and in pus,® occasionally in diabetic urine,’ but is specially abundant in 


1. Zander finds that the iodine reaction given by polysaccharides and by chitin varies 
considerably with the solvent used (Arch. fi d. ges. Physiol., Bonn, 1897, Bd. Ixvi. 
S. 545). 

2 Brown, Morris, and Millar, doc. cit. 

3 Kulz, ‘‘ Beitr. z. Path. des Diabetes,’ _ Marburg, 1894, S. 130. ; Worm-Miiller, Arch. 
f. d. ges. Physiol., Bonn, 1884, Bd. xxxiv. 8. 576 ; 1885, Bd. xxxvi. S. 12s Hofmeister, 
Arch. f. exper. Path. u. Pharmakol., Leipzig, 1889, Bd. xxv. S. 240. On “Inulin as a 
Precursor of Glycogen,” see Miura, Zschr. is Biol., Miinchen, Bd. xxxii.; he obtained 
very inconstant results. : 

+ Nilson, Upsala Liékaref. Forh., vol. xxviii., quoted by Hammarsten, in ‘‘ Physiol. 
Chem.,” 3rd German edition, S. 67. 

5 Salomon, Deutsche med. Wehnschr., Leipzig, 1877, Nos. 8 and 35; Centralbl. f. 
Physiol., Leipzig, Bd. vi. S. 512; Huppert, Centralbl. f. Physiol., Leipzig, Bd. vi 
S. 394. 

6 Salomon, Joc. cit. 

7 Leube, Virchow’s Archiv, Bd. exiii. S. 391. 


THE POL VSACCHARIDES. 15 


liver and muscle} in embryonic tissues generally? and in the bodies of 
molluses.2 It has been described in pathological growths,* and in 
the vegetable kingdom in many fungi’ (truffles, mucor, yeast, 
myxomycetes). 

It may be dissolved out with boiling water (Briicke),® 2 per cent. 
potash (Kiilz),’ or by trichloracetic acid,* from the tissues in which it 
occurs. The extraction with this acid is, however, incomplete, and the 
product is impure.® Huizinga!’ recommends that glycogen should be 
extracted from the liver by a mixture of equal parts of saturated 
solution of mercuric chloride, and Esbach’s reagent (10 grms. of picric 
and 20 of citric acid in a litre of water). From this solution, 


which is proteid free, glycogen is precipitable by alcohol. 


The pure material is a white tasteless powder, soluble in water, forming 
a strongly opalescent solution. It is imsoluble in alcohol and in ether. 
It is strongly dextrorotatory ;" («), =+196°63. With Trommer’s test 
it gives a blue solution, but no reduction occurs on boiling. 

With iodine it gives a port-wine red colour, which easily distin- 
guishes it from starch. Its precipitability by basic lead acetate dis- 
tinguishes it from dextrin. 

Prolonged boiling with water or boiling with dilute mineral acids 
converts it into sugar. The diastatic ferments act similarly. 


Max Cremer ? investigated the action of dilute acids on glycogen ; he 
found glucose and isomaltose (identified by their osazones), but no maltose. 
Kiilz and Vogel }* investigated the action of diastatic ferments ; parotid saliva 
produced isomaltose and maltose in the proportion of 1 to 2 from liver-glycogen, 
and isomaltose with small amounts of maltose and dextrose from muscle- 
glycogen ; pancreatic juice and malt diastase produced practically the same 
result. The ferment in the liver which acts on glycogen produces dextrose. 

The physiological relationships of glycogen will be treated elsewhere. 
There is much controversy on the subject of the origin and fate of glycogen. 
There is, however, little doubt that it is chiefly a storage product from the 
carbohydrates of the food, and that after death it is transformed into dextrose ; 
the principal controversies of recent years have centred round the question 
whether glycogen normally leaves the liver in the hepatic blood as sugar (as 


1 Claude Bernard, Compt. rend. Acad. d. sc., Paris, 1857, tome xliv. pp. 578 and 1325 ; 
xlviii. pp. 77, 683, 763 and 784; Hensen, Virchow’s Archiv, 1857, Bd. xi. S. 395; O. 
Nasse, Arch. f. d. ges. Physiol., Bonn, 1869, Bd. ii. S. 97. 

2 Claude Bernard, ‘‘ Physiologie expér.,” 1855, tome i. p. 241; iv. p. 44; Salomon, 
Centralbl. f. d. med. Wissensch., Berlin, 1874, S. 738 ; Moriggia, ibid., 1875, S. 186; v. 
Wittich, Hermann’s ‘‘ Handbuch,” 1883. 

3 Bizio, Ztschr. f. Chem., Leipzig, 1866, S. 222; Bernard, ‘‘ Lecons sur les phénoménes 
de la vie,” 1879, tome ii. ; Krukenberg, ‘‘ Vergl. physiol. Studien,” 1880, Bd. ii. S. 52. 

4Kiihne, Virchow’s Archiv, Bd. xxxii. S. 536; Sotnitschewski, Ztschr. f. physiol. 
Chem., Strassburg, 1880, Bd. iv. S. 220. 

5 Kiihne, ‘‘ Lehrbuch der physiol. Chem.,” 1868, S. 334; Reinke and Rodewald, 
“Studien ueber das Protoplasma,” Berlin, 1881, S. 34, 54, and 169; Errera, Bull. Acad. 
roy. de méd. de Belg., Bruxelles, Bd. iv. 8. 451. 

8 Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1871, Bd. Ixiii. S. 214. 

7 Ztschr. f. Biol., Miinchen, 1886, Bd. iv. S. 191. 

8 Frankel, Arch. f. d. ges. Physiol., Bonn, Bde. lii. 8. 125; lv. S. 378. 

® Weidenbaum, zbid., Bde. liv. S. 319; lv. S. 380. 

Arch. f. d. ges. Physiol., Bonn, Bd. 1xi. 

U Huppert, Ztschr. f. physiol. Chem., Strassburg, Bd. xviii. S, 137. 

P Ztschr. f. Biol., Miinchen, 1894, Bd. xxxi. S. 181. 13 Tbid., S. 108. 

14 According to Voit and his pupils (Zéschr. f. Biol., Miinchen, Bd. xxviii. S. 245), the 
liver forms glycogen only from dextrose and levulose, or from those carbohydrates which 
are converted into these sugars before they reach the liver. 


16 CHEMICAL CONSTITUENTS OF BODY AND FOOD: 


Bernard originally taught), or is employed in the synthesis of fat and proteid 
(as Pavy holds). 


Dextrin is the name given to a number of intermediate substances 
formed during the hydrolysis of starch; the principal varieties are 
erythrodextrin, which gives a red colour with iodine; achroddextrin, which 
does not; and maltodextrin, which has a lower molecular weight than 
these! The dextrins are dextrorotatory (maltodextrin has an («), =+ 
174°°5). They are soluble in water, and insoluble in alcohol and ether. 
They give a blue solution with Trommer’s test, but no reduction occurs 
on boiling. 


Animal gum was discovered by Landwehr,” and resembles achroédextrin 
and glycogen in some of its properties. It is a decomposition product of 
mucin. When boiled with dilute sulphuric acid it yields a reducing but 
unfermentable sugar. Animal gum, like the vegetable gums, gives gelatinous 
precipitates with copper and iron salts. 

Animal dextran is a gummy material, secreted by the Schizoneura 
lanuginosa, a gall-producing louse that attacks elms.* 

Vegetable gums and mucilages include such substances as gum arabic, 
wood gum, etc., which are of subordinate physiological interest. 


Cellulose is the name given to a number of carbohydrates which form 
the chief constituent of vegetable cell walls. In old cells, where it 
becomes very insoluble, it is called lignin. The celluloses are insoluble 
in eold and hot water, in aleohol, ether, and dilute acids and alkalies. 
A specific reagent for dissolving them is Schweitzer’s reagent (a solution 
of cupric hydrate in ammonia). 

With iodine and concentrated sulphuric acid they are turned blue; 
with nitric acid they yield nitroso-compounds of an explosive nature. 
Prolonged treatment with strong mineral acids leads to the formation of 
sugars; in some cases glucose, in others mannose, is formed. Schulze’s 
mannoso-cellulose,t found in coffee and other seeds, is not a hemicellu- 
lose (see next paragraph). The celluloses are not acted upon by the 
digestive ferments proper; but they may be broken up in the intestine 
by bacteria into carbonic acid and methane. 


Hemicelluloses are those varieties of cellulose which differ from the others 
by yielding monosaccharides by treatment with ddlute mineral acids. The 
hemicellulose of yellow lupins yields galactose and arabinose ; that of rye and 
wheat, arabinose and xylose ; that of certain nuts, mannose.® 

Tunicin is animal cellulose. It is the chief constituent of the test or outer 
investment of the tunicates.°® 

Cellulose has also been found in the animal kingdom in the skin of the 
silkworm,’ and in the zoocytium of Ophrydium versatile.§ 


Inosite.—Inosite is a substance found in muscle and other animal 
tissues, and in many vegetables also. Its crystalline form is shown 


1 Recent papers on dextrin will be found in Ber. d. deutsch. chem. Gesellsch., Berlin, 
Bde. xxiii. S. 3060; xxvi. S. 2930 (by Scheibler and Mittelmeier), and Bd. xxvi. 5. 
2533 (by Leubner and Doll). 

2 Zischr. f. physiol. Chem., Strassburg, Bd. viii. S. 119, 124. 

3 Liebermann, Arch. f. d. ges. Physiol., Bonn, Bd. xl. S. 454. 

4 Ztschr. f. physiol. Chem., Strassburg, Bd. xvi. 

5 See Schulze, Joc. cit. ; and Reiss, Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. xxii. 

6 Schafer, Ann. d. Chem., Leipzig, Bd. ccx. S. 312; Berthelot, Ann. de chim., Paris, 
Sér. 3, tome lvi. p. 153. 

7 De Lucca, Compt. rend. Acad. d. sc., Paris, tome lii. p. 102; lvil. p. 48. 

8 Halliburton, Quart. Journ. Micr. Sc., London, July 1885. 


THE FATS. | 


in Fig. 5. For many years it was regarded as a carbohydrate, though an 
exceptional one. It is sweet to the taste, but it gives none of the 
characteristic reactions of sugar. As the chemical constitution of the 
sugars was revealed, it became more and more evident that inosite is 
not a sugar. Its constitution was 
worked out by Maquenne! from a 
study of its nitro-substitution and 
other products. It belongs to the 
substances which have a_ closed 
earbon chain, and its graphic formula 
may be written thus :— 


CHOH 
Fae 
CHOHY \CHOH 


et) SH0n 


CHOH 


Fic. 5.—Inosite crystals.—After Frey. 


THE Farts. 


Fat is found in most of the animal tissues. The following table from 
Gorup-Besanez gives the percentage in the organs and fluids of the body :— 


Sweat . : ; 0-001 Cartilage 1:3 
Vitreous humour . 0-002 Bone . ; 1-4 
Saliva . ; t 0-02 Crystalline lens 2°0 
Lymph . : : 0-05 Liver . 2-4 
Synovia : ; 0:06 Muscles 3°3 
Liquor amnii : 0:06 Hair . 42 
Chyle ; 0-2 Brain -., 8:0 
Mucus . : ; 0°3 as. LG 
Blood . ‘ ; 0-4 Nerves : | 
Bile” ..| 1. . : 1-4 Adipose tissue . 82°71 
Milk . : ‘ 4°3 Marrow ig GO 


The fats are usually extracted from the finely divided tissue by 
means of ether in a Soxhlet’s apparatus, but in the case of many organs 
the extraction is incomplete. Dormeyer therefore recommends that 
the tissue should be subjected to artificial gastric digestion before the 
extraction with ether;* when this was done, flesh was found to yield an 
additional 0°75 per cent. of fat. 


The fats are compounds of fatty acids with glycerin, and are termed 
glycerides or glyceric ethers. The fatty acids form a series of acids derived 
from the monatomic alcohols by oxidation ; thus— 


From methyl alcohol (CH,HO) formic acid (H.COOH) is obtained. 
From ethyl] alcohol (C,H;HO) acetic acid (CH,COOH) is obtained, and so on. 


1 Compt. rend. Acad. d. sc., Paris, 1887, tome civ. pp. 225, 297, 1719, 1858. For colour 
reactions of inosite, see Scherer, dnn. d. Chem., Leipzig, 1852, Bd. lxxxi. S. 375 ; Gaulois, 
Ztschr. f. anal. Chem., Wiesbaden, 1865, Bd. iv. S. 264; Seidel, Ber. d. deutsch. chem. 
Gesellsch., Berlin, 1887, Bd. xx. S. 320. 

2 Arch. f. d. ges. Physiol., Bonn, 1895, Bd. Ixi. S. 341; 1896, Bd. lxv. S. 90; F. N. 
Schulze (tbid., Bd. Ixv. S. 299; 1897, Ixx1i. S. 145) has used the same method for the 
extraction of the fat of blood, and numerous organs. 


NOE 2 


18° CHEMICAL CONSTITUENTS OF BODY AND FOOD, 


Or, in general terms 

From the alcohol with formula C,H,,,,.HO the acid with formula 
C,_,H,,-;-CO.OH is obtained. The sixteenth term of this series has the 
formula C,;H,,.CO.OH, and is called palmitic acid ; the eighteenth has the 
formula C,-H,..CO.OH, and is called stearic acid. Each acid, as will be seen, 
consists of a radicle, C,,_,H,, ,CO, united to hydroxyl (HO). 

Oleic acid, however, is not a member of this series, but belongs to a some- 
what similar series of acids known as the acrylic series,! of which the general 
formula is C,_,H,,,COOH. It is the eighteenth term of the series, and 
its formula is C,-H,..CO.OH. 

Glycerin or glycerol is a triatomic alcohol, C,H,(OH).—7.e. three atoms of 
hydroxyl united to a radicle glyceryl (C.,H,). 

The hydrogen in the hydroxy] atoms is replaceable by other organic radicles. 

As an example, take the radicle of acetic acid, called acetyl (CH,.CO). The 
following formule represent the derivatives that can be obtained by replacing 
one, two, or all three hydroxyl hydrogen atoms in this way :— 


(ou (OH (OH 0.CH,.CO 

C,H,JOH C,H,/ 0H C,H,,0.CH,CO C,H,/0.CH,.CO 

[OH | 0.CH,.CO | 0.CH..CO 0.CH,.CO 
(glycerin) (monoacetin) (diacetin) (triacetin) 


The contents of the fat cells of adipose tissue in man are fluid during 
life, the normal body temperature being higher than the melting point 
of the mixture of fats found there; but this is not the case in all 
(even warm-blooded) animals, for beet fat melts at about 45° C., and 
mutton fat at a still higher temperature. Human fat consists of 
the three glycerides—palmitin, stearin, and olein. They differ in 
chemical composition, melting point, and solubilities. Olein melts at 
—5° C., palmitin at 45° C., and stearin at 53° to 66° C. It is thus olein 
which holds the other two dissolved at the body temperature. All are 
soluble in hot alcohol, ether, and chloroform, but insoluble in water. 

The proportion in which these fats are mixed differs in different 
anunals; in cold-blooded animals olein is much more abundant than in 
warm-blooded animals. Human fat contains from 67 to 80 per cent. 
of olein. Mixed with these neutral fats, there is generally a small 
amount of free fatty acids. 

Fats are also found in the vegetable kingdom, especially in seeds and 
fruits, but in many cases in the roots also. 


Stearin, palmitin, and olein ought more properly to be called tristearin, 
tripalmitin, and trioiein respectively. Each consists of glycerin, in which the 
three atoms of hydrogen in the hydroxyls are replaced by radicles of the fatty 
acid. This is represented in the following formule :— 


Acid. | Radicle. Fat. 


| Palmitic acid C,,H,,.COOH | Palmityl C,,H,,.CO| Palmitin C,H,(OC,,H,,.CO), 
| Stearic acid . C,,H,,.COOH | Stearyl . C,,H,;.CO | Stearin . C,H,(OC,,H;;.CO), 
Lee acid . C,,H,,-COOH | Oleyl .C,,H,,.CO|Olen ~. C,H,(OC,,H,,:€0), 


1 Acrylic acid itself (C,;H,O,) is obtained by the oxidation of acrolein (C,H,O), the 
aldehyde of allyl alcohol. 


——e ee ee 


a 


Pid eee 


THE FATS. 19 


Under the influence of superheated steam, mineral acids, and in the 
body by means of certain ferments (for instance, the fat- splitting 
ferment of the pancreatic juice), a fat combines with water and _ splits 
into glycerin and the fatty acid. The following equation represents 
what occurs in a fat, taking tripalmitin as an example :-— 


O3H,(0.0y F100) s+ 3H0 = C.11( O11) + 30,100.01 
(palmitin—a fat) (s i cerin) (palmitic acid —a 
fatty acid) 


Saponification.—In the process of saponification much the same sort 
of reaction occurs, the final products being glycerin and a compound of 
the base with the fatty acid, which is called a soap. 

Suppose, for stance, that potassium hydrate is used, we get— 


oe (OCH, CO),+ 3K HO— Ch (OH), +-3C,,H,,CO.0K 

(palmitin—a fat) (glycerin) (potassium palmitate 
—a soap) 
To separate the neutral fats from one another, they have always to be 
saponified; this can be accomplished by potassium hydrate, or still 
better by sodium alcoholate (Kossel, Obermiiller, and Kriiger)2 On 
evaporation of the alcohol, the soaps are dissolved in water, and pre- 
cipitated by sugar of lead; the lead compound of oleic acid is soluble in 
ether; the remaining soaps are treated with soda on the water bath, 
dried, dissolved in alcohol, and separated by fractional precipitation with 
barium acetate or barium chloride. 

In the decomposition of fat, propionic, acetic, and formic acids may 
be found, which are absent from the fat in the fresh condition. This 
occurs when the fat becomes rancid, and is also produced by putre- 
factive organisms in the alimentary canal. The process is one of 
oxidation, and the way in which lower terms of the series are produced 
may be illustrated by the following equations :— 


C,H,0,+-0,=C,H,0,+-C0,+ H,0. 


(propionic acid) (acetic acid) 
C,H,0,+0,=CH,0,+C0,+H,0. 
(acetic acid) (formic acid) 


2CH,0,+0,—200,4 2H,0. 


(formic acid) 


Emulsification—Another change that fats undergo in the body is very 
different from saponification. It is a physical rather than a chemical 
change; the fat is broken up into very small globules, such as is seen in 
the natural emulsion—milk. 

The fats of mk resemble in a general way those of adipose tissue, 
but there is a considerable admixture of glycerides lower in the series 
(see “ Milk ”). 

The fats of marrow are also like those of adipose tissue. As will be 
noticed in the table on p. 17, bone marrow is the tissue which is richest 
of all in fat. 


Eylert? described a new fatty acid in the marrow of ox-bone which he 
called medullic acid, but this was shown by Mohr® to be only stearic acid. 


1 Numerous papers in vols. xiv., xv., and xvi. of Zéschr. f. physiol. Chem., Strassburg. 
2 Vrtljschr. f. prakt. Pharmakol., Bd. ix. S. 330. 
3 Zischr. f. physiol. Chem. , Strassburg, 1890, Bd. xiv. S. 390. 


20 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


Mohr gives the proportion of the acids in marrow fat as—palmitic acid, 22 ; 
stearic acid, 10; and oleic acid, 63 per cent. 

Among the exceptional forms of fat are the following :— 

Spermaceti, obtained from the sperm whale. This fat sets into a solid, 
white crystalline mass, melting at from 30° to 50°C. _ Its chief constituent 
is the palmitate of cetyl alcohol, or ethal (C,,H,;0H). This alcohol is the 
one from which palmitic acid is derived in the same way as acetic acid 
is derived from ethyl alcohol. Spermaceti contains also small quanti- 
ties of compounds of lauristic, myristic, and stearic acids, with the 
radicles of the alcohols lethal (C,,H,,OH), methal (C,,H,,OH), and 
stethal (C,,H,,OH). 

Beeswax contains three chief constituents :— 

(1) Myricin; this is its principal constituent; it is the palmitate of 
myricyl alcohol (C,,H,,OH) ; (2) Cerotic acid (C,,H,,0,); and (3) Cerolein, 
which is probably a mixture of several substances. 

Chinese wax is chiefly the cerotic acid compound of cerotyl alcohol 
(C,,H,,0H).? 

Adipocere is the name given to a waxy substance which replaces the 
muscular tissue in corpses buried in damp soil, or which have been 
allowed to remain in water some time after death. It consists chiefly 
of the calcium soaps of palmitic and stearic acids, and in some cases of 
acid ammonium soaps also. Hoppe-Seyler? considered that the change 
is the result of a ferment action. 


LIPOCHROMES, LECITHIN, CHOLESTERIN. 


Lipochromes.—This name is given to the pigments which occur in 
fat and fatty tissues. They are mostly yellow or yellowish red. They 
include the pigment of the blood serum (serum lutein) and of the corpus 
luteum ; the chromophanes or coloured oil globules of the retinal cones ; 
the yellowish pigment in butter, adipose tissue, and egg-yolk; tetronery- 
thrin, a reddish pigment, found in many invertebrates; and several 
vegetable pigments, such as carrotin, which is found in carrots and 
tomatoes. The lipochromes have been separated by their various 
solubilities after saponification; they give various colour reactions, such 
as a greenish-blue colour with iodine and sulphuric acid, and a green 
colour with nitric acid; they show absorption-bands towards the 
violet end of the spectrum, and especially in the region of the F line. 

Nothing is known about their chemical constitution ; carrotin, which 
has been examined more fully than the others, has been assigned the 
formula C,,H,,0 by Husemann, and C,,H,, by Arnaud.* 


1 On these rarer forms of fat and wax, see Liebermann, Ber. d. deutsch. chem. Gesellsch., 
Berlin, 1885, Bd. xviii. S. 1975. 

* Quain, Med.-Chir. Trans., Bonden, 1850, p. 141; Virchow, Verhandl. d. phys.-med. 
Geselisch. in Wiirzburg, Bd. iii. ; Wetherill, Journ. f. prakt. Chem., Leipzig, Bd. Ixviii. S. 

kK. B. Lehmann, Ce ontralbl. f Agric. Chem., Leipzig, 1889, S. 66. 

8 “ Physiol. Chem.,” Strassburg, S. 119. According to some authors, its formation is 
brought about by micro-organisms s (Jacobsthal, Arch. }. d. ges. Physiol., Bonn, 1893, Bd. 
liv. S. 499. 

‘The principal papers on lipochromes are the following :—On lutein—Thudichum, 
Centralbl. f. d. med. Wissensch., Berlin, 1869, Bd. vii. S.1. On colour reactions of 
luteins—Thudichum, Joc. cit. ; Piccolo and Lieben, Gior. de sc. nat. ed. econ., Palermo, 
vol. ii. p. 258; Caprarnica, Arch. f. Physiol., Leipzig, 1877, S. 283.; Schwalbe, 
‘*Handb. d. ges. Augenheilkunde,” Leipzig, 1874, Bd. i. S. 414. On chromophanes 
—Kiihne and Ayres, Journ. Physiol., Cambridge and London, 1878, vol. i. 
p. 109; Untersuch. a. d. physiol. Inst. d. Univ. Heidelberg, Bd. i. Heft 4. On 


LECITUALIN: 21 


Lecithin is a complex fat of wide distribution. It is a constant 
constituent of protoplasm, and is found both in the animal and 
vegetable! world. In the animal tissues, it is found principally in 
the brain and nervous tissues, where it is probably a decomposition 
product of a more complex substance originally called protagon by 
Liebreich? (see section on “Chemistry of Nervous Tissues”); in yolk 
of egg;* and in blood corpuscles. Lecithin is found in all organs 
composed of cells, and also in certain secretions, namely, semen, bile, 
and milk. 

Lecithin is a yellowish white, waxy, hygroscopic solid, soluble in 
ether and in alcohol; it swells and forms a kind of emulsion with 
water. When ignited it burns and leaves a residue of metaphosphoric 
acid. Its most important compounds are those of its hydrochloride 
with platinum chloride (C,,H,NPO,Cl),+PtCl,, and with cadmium 
chloride which has a corresponding formula.? 

Montgomery ° showed that when water, glycerin, and other reagents 
were added on a microscopic slide to impure lecithin (or protagon, as he 
termed it), prepared from egg-yolk, snake-like forms shoot out, bending 
and curling and even simulating nerve fibres or nerve cells. On 
cooling a solution of lecithin in alcohol, it separates out in erystal- 
line clumps. On decomposition by alkalis, it yields glycero-phosphoric 
acid, a fatty acid, and an alkaloid choline. 

Choline is an ammonium base, and has the following constitution :— 


(teins Seer 
i Bal iis C,H,,NO, 


It is therefore trimethyl-oxyethyl-ammonium hydroxide; its name 
is derived from the fact that it was first separated from the lecithin of 
the bile. Its synthesis was accomplished by Wurtz? from ethylene 


tetronerythrin—Wurm, Zischr. f. wissensch. Zool., Leipzig, 1871, Bd. xxxi. 8. 535; 
Merejkowski, Compt. rend. Acad. d. sc., Paris, 1881, tome xcili. p. 1029; MacMunn, Proc. 
Birmingham Phil. Soc., vol. iii. p. 351; Proce. Roy. Soc. London, 1883, No. 226, p. 17 ; 
Halliburton, Journ. Physiol., Cambridge and London, 1884, vol. vi. p. 324; Krukenberg, 
Centralbl. f. d. med. Wissensch., Berlin, 1879, Bd. ix. S. 705. On serum lutein— 
Krukenberg, Sitzungsb. d. Jenaisch. Cresellsch. f. Med. u. Naturw., 1885; Halliburton, Journ. 
Physiol., Cambridge and London, 18835, vol. vii. p. 324. On saponification of lipochromes 
—Kiihne, Joc. cit. ; Maly, Monatsh. d. Chem., Wien, 1881, Bd. ii. S. 351; Bein, Ber. d. 
deutsch. chem. Gesellsch., Berlin, 1890, Bd. xxiii. S. 204. On carrotin—Husemann, Ann. d. 
chem., Leipzig, Bd. exvii. S. 200; Arnaud, Compt. rend. Acad. d. sc., Paris, tome cil, 
p- 119; civ. 1293. Newbiggin, ‘‘On Crustacean Pigments,” Journ. Physiol., Cambridge 
and London, 1897, vol. xxi. p. 237. 

10n the subject of lecithin and choline in vegetable oils, etc., see Heckel and 
Schlagdenhauffen, Compt. vend. Acad. d. se., Paris, tome cili. p. 188; Jacobson, Ztschr. f. 
physiol. Chem., Strassburg, Bd. xxiii. S. 33; Schulze, ibid., Bde. xi. S. 365; xii. S. 441; 
xvii. S. 204; J. Stoklasa, Ber. d. deutsch. chem. Gesellsch., Berlin, 1896, Bd. xxix. 8. 2761. 

2 Ann. d. Chem., Leipzig, Bd. exxxiv. S. 29. 

3Gobley, Journ. de pharm. et chim., Paris, tomes xi., xii., xvil., xvili. ; Parke, 
Hoppe-Seyler’s “‘ Med. Chem. Untersuch.,” Berlin, Heft 2, S. 213 ; Hoppe-Seyler, ibid., S. 
215 ; Diaconow, ibid., S. 221; Centralbl. f. d. med. Wissensch., Berlin, 1868, S. 2. 

4Gobley, Journ. de pharm. et chim., Paris, tome xxi. p. 250; Hermann, Arch. 
f. Anat. wu. Physiol., Leipzig, 1866, S. 33; Hoppe-Seyler, ‘‘ Med. Chem. Untersuch.,” Berlin, 
Heft 1, S. 140; Jiidell, ibid., Heft 3, 8. 386. 

5 The formation of these compounds enables one to prepare lecithin in a pure form, the 
metal being subsequently got rid of by sulphuretted hydrogen. 

6 <*On the Formation of So-called Cells,” London, 1867. 

7 Ann. d. Chem., Leipzig, 1868, Supplement, Bd. vi, 8. 116 and 197 ; see also Bayer, 
ibid., Bd. exl. S, 306, 


22 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


oxide (C,H,O), trimethylamine N(CH,),, and water. It was at one time 
thought to be identical with the base neurine, which Liebreich separated 
from nervous tissues, and the two are closely related; empirically 
choline (C;H,,;NO,) is neurine (C;H,,NO), plus water. In constitution 
neurine is trimethylvinylammonium hydroxide. 

tlycero-phosphorie acid is glycerin, in which one of the hydroxyl 
hydrogens is replaced by phosphoric acid, less hydroxyl; thus— 


HO OH 
C,H,HO (H,P0,)HO C,H,OH 

HO O—PO,H, 
(glycerin) (phosphoric acid) (gly cero- Heesnbena acid) 


If the other two hydroxyl hydrogens are replaced by the radicle of 
stearic acid, we obtain 

CH,.O—C,,H,,CO 

CH .O—C,,H,,CO 

ets (OH 

CH,O—P0) 64 
which is distearyl-glycero-phosphoric acid. This is then united to 
choline (less hy droxyl), and we obtain lecithin, or distearyl lecithin, as 
it should be more properly termed; for other lecithins exist in which 
palmityl, oleyl, or other fatty acid radicles take the place of stearyl. 


The exact manner of the union of the acid with choline is a matter of 
controversy, for up to the present lecithin has not been prepared synthetically. 
Hundeshagen ! prepared artificially a choline salt of distearyl-glycero-phosphorie 
acid, which is isomeric with lecithin, but which possesses none of its 
characteristic properties. 

The constitution of lecithin is not therefore that of a salt in which choline 
plays a part of the base, as Diaconow? first suggested, but more probably it 
is an ether-like combination, the choline radicle being united to the acid by 
means of the oxygen of the hydroxyl; the formula for distearyl-lecithin 
would therefore be (Strecker) ?— 


CH,.O—C,-H,,CO 

CH. 0—C, “H,CO 

CH, Oe POL50: Caen ale 
| (CH, ys 
OH 7H@. alee 


The following equation represents the decomposition of lecithin, such 
as occurs on boiling it with alkaline solutions :— 
CuH,,.N.PO-3H,0 = 2C,,H,,0,4CH, BO eee 


(lecithin) (stearic acid) — (glycero- (choline) 
phosphoric acid) 


Cholesterin.—Cholesterin is contained in small quantities in all proto- 
plasmic structures ; it is also found in blood corpuscles and in bile. It is a 
large constituent of sebum and similar oily secretions of the skin. In 
nervous tissues it 1s an especially abundant constituent of the white sub- 
stance of the medullary sheath. It may be prepared by making a hot 


1 Journ. f. prakt. Chem., Leipzig, 1883, Bd. xxviii. S. 219 ; see also E. Gilson, Zéschr. f. 
physiol. Chem., Strassburg, Bd. xii. S. 585. 
2 Centralbl. f. d. med. Wissensch., Berlin, 1868. 
3 Ann. d, Chem., Leipzig, 1868, Bd. exlviii. S. 77. 


CHOLESTE RIN. 23 


alcoholic extract of the brain or spinal cord; on cooling, the cholesterin, to- 
gether with protagon and cerebrin, separates out. From this mixture the 
cholesterin is dissolved out with ether, and the ether distilled off. To 
get rid of traces of lecithin it is heated for an hour with alcoholic potash ; 
this decomposes the lecithin, and the residue obtained by evaporating to 
dryness is dissolved ina mixture of alcohol and ether; from this solution, 
cholesterin crystallises out as its solvents evaporate off. 

Cholesterin is readily obtained from gall stones by simply extracting 
them with boiling alcohol, and treating with alcoholic potash to free it 
from extraneous matter. 

Like the fats, cholesterin is insoluble in water, but freely soluble 
in hot or cold ether, glycerme, benzol, hot alcohol, and chloro- 
form. From anhydrous ether or chloro- 
form it separates in the form of needles, 
containing no water of crystallisation ; 
from alcohol, or ether containing water, 
it separates in the form of rhombic, 
bright tables, which contain a mole- 
cule of water of crystallisation, and 
are easily identified by the microscope 
(Fig. 6). 

Dry cholesterin melts at 145°, distils in 
vacuo at 360° C.; its specific rotatory power 
is (z),=— 31°°6. It may be recognised by Fc. 6.— Cholesterin crystals.— 
the following colour tests :— After Frey. 

1. With iodine and concentrated sulphuric acid the crystals give a 
play of red, green, and blue. 

2. Salkowski’s reaction..—The cholesterin is dissolved in chloroform 
and an equal volume of concentrated sulphuric acid added; the solution 
becomes first red and then purplish, while the sulphuric acid is dark red 
with a green fluorescence. On pouring off the chloroformic solution, it 
becomes green and finally yellow. 

3. Liebermann-Burchard’s reaction.2—This is a very delicate test, and 
is stated to be capable of detecting one part of cholesterin in 20,000 of 
solvent. The cholesterin is dissolved in 2 ¢.c. of chloroform, and ten 
drops of acetic anhydride are added, and then concentrated sulphuric 
acid drop by drop. The mixture becomes first red, then blue, and 
finally green. 

Cholesterin is a monatomic alcohol, the formula of which has been 
given as C,,H,OH and C,,H,OH. The second formula was first 
ascribed to the substance by Reinitzer,? and it is probably the correct 
one, as it has been confirmed by the careful work of Obermiiller.4 These 
observers have prepared a large number of compounds and derivatives 
of cholesterin, but its constitution still remains unknown. 


The subject is complicated by the circumstance that there are several 
isomeric cholesterins. 


1 Arch. f. d. ges. Physiol., Bonn. Bd. vi. 

2 Liebermann, Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. xviii. S. 1804; Burchard, 
** Beitrage zur Kenntniss der Cholesterine,” Rostock, 1889. 

3 Reinitzer, Monatsh. f. Chem., Wien, 1888, Bd. ix. s. 421. 

4 Arch. f. Physiol., Leipzig, 1889; Ztschr. f. physiol. Chem., Strassburg, 1889, Bde. 
Meo hs xvi. oO. 143, 152. 


24 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


It forms, like glycerine, compounds often called esters, with fatty acids ; 
and these compounds, which are found in the fatty secretions of the skin, 
especially in the fat of sheep’s wool (lanoline), are very resistant to bacterial 
action ; as a protection to the skin lanoline is therefore admirable. 

In lanoline there are two cholesterins at least; one is levorotatory, the 
other (isocholesterin) is dextrorotatory. Isocholesterin was first described 
by Schultze,! and does not give Salkowski’s reaction. 

Cholesterins of various kinds are present in vegetable tissues.” 

The cholesterin of the blood is in combination with oleic and palmitic 
acids.® 

In man the cholesterin of the bile passes: away in the feces as koprosterin 
(C,-H,.O) ; in the horse as hippokoprosterin (C,-H,,0 or C,-H.,O) ; in the dog 
it is unchanged. 


THE PROTEIDSs.® 


The proteids are the most important substances present im animal 
and vegetable organisms; none of the phenomena of life occur without 
their presence ; they are constant decomposition products of, and therefore 
probable constituents of, protoplasm. 

“They are highly complex and, for the most part, uncrystallisable 
compounds of carbon, hydrogen, oxygen, nitrogen, and sulphur,’ occurring 
in a solid, viscous condition, or in solution in nearly all the solids and 
liquids of the organism. The different members of the group present 
differences in physical, and to a certain extent even in chemical 
properties. They all possess, however, certain common chemical reactions, 
and are united by a close genetic relationship ” (Gamgee).7 


The following table from Gorup-Besanez® exhibits the percentage of 
proteids contained in the liquids and solids of the body :— 


Cerebro-spinal fluid. 0:09 Chyle 4:09 
Aqueous humour. : 0-14 Blood : ; 8°56 
Liquor amnii 4 : 0-70 Spinal cord . : 7:49 
Intestinal juice. : 0-95 Brain . : E 8°63 
Pericardial fluid . : 2°36 | Liver . : : 11-64 
Lymph : ‘ : 2°46 Thymus : : 12°29 
Pancreatic juice . : 3°33 Muscle : ‘ 16°18 
Synovia. : ; 39] Tunica media of arteries 27°33 
Milk . : : 3°94 | Crystalline lens . 38°30 


1 Ber, d. deutsch. chem. Gesellsch., Berlin, Bd. vi. ; Journ. f. prakt. Chem., Leipzig, 
N.F., Bd. xxv. S. 458; Ztschr. f. physiol. Chem., Strassburg, Bd. xiv. S. 522. On 
isocholesterin in vernix caseosa see Rappel, ibid., Bd. xxi. S. 122. 

> Beneke, Jahresb. ii. d. Leistung. ... . d. ges. Med., Berlin, 1862; Hesse, Ann. d. 
Chem., Leipzig, Bd. excii. S. 177; Bd. ecx., S. 283; Reinke and Rodewald, zbid., Bd. 
eevii. S. 232 ; Schulze and Barbieri, Journ. f. prakt. Chem., Leipzig, N.F., Bd. xxv. S. 
159, 458 ; Heckel and Schlagdenhauffen, Compt. rend. Acad. d. sc., Paris, 1886, tome cii. 
p. 1317 ; Arnaud, zbid., p. 1319. See also Jacobson’s paper on ‘‘ Vegetable Oils,” Zéschr. 
J. physiol. Chem., Strassburg, Bd. xiii. 8. 32. 

°K. Hiirthle, Zschr. f. physiol. Chem., Strassburg, 1896, Bd. xxi. S. 331. 

*St. Bondzynski and V. Humnicki, Zschr. f. physiol. Chem., Strassburg, 1896, Bd. 
xxii. S. 396. 

° In the preparation of this section I have derived special assistance from the articles 
“* Kiweisskorper,” in Beilstein’s ‘‘ Handbuch der org. Chemie,” and in Ladenburg’s 
‘*Handworterbuch d. Chemie,” 1885, Bd. iii. S. 534 (article by E. Drechsel) ; and from 
an article by T. G. Brodie in Science Progress, London, 1895, vol. iv. p. 62. 

6 In some cases phosphorus also is present. 

7 “ Physiological Chemistry,” London, vol. i. p. 4. 

8 “Lehrbuch,” S, 128. 


Ss eT CC ee Tr 


COMPOSITION OF THE PROTEIDS. 25 


The proteid constituents of the animal body are derived from 
vegetables either directly, or indirectly through the body of another 
animal. Synthetie processes do occur in the “animal body,! but to a 
much greater extent in vegetables; here the proteids are built up from 
simpler compounds, derived ultimately from the soil and atmosphere. 
In animals, the proteids are converted during digestion into hydrated 
products, called peptones; these are re-converted into proteids, 
similar, in a general sense, to those originally ingested, and these are 
assimilated to become part of the living organism. In time, they 
become subjected to katabolic processes, and give rise to carbonic acid, 
sulphuric acid, water, and certain not fully oxidised products (urea, uric 
acid, ete.) which contain the nitrogen of the original proteid. 

Composition of the proteids.—Various proteids differ a good deal 
in elementary composition, as is seen by the following percentages :— 


From From 
Hoppe- Seyler.” Drechsel.® 
C 51°5 to 54°5 50:0 to 55:0 
H 6-9 ph Oa, to 
N Toe2 ae 15°4 ,, 18-2 
O 20-9 ,, 23°D 22°8 ,, 24:1 
S area O40 250 


In addition to the above constituents, many proteids or proteid-like 
substances contain small quantities of phosphorus; and practically all 
proteids leave on ignition a variable amount of ash. In the case of egg- 
albumin the chief substances in the ash are chlorides of potassium and 
sodium, and smaller quantities of phosphoric, sulphuric, and carbonic 
acids, in combination with sodium, potassium, calcium, magnesium, and 
iron. There may also be a trace of silica.* The ash of serum pro- 
teids contains an excess of sodium chloride, and that of muscle proteids 
a preponderance of potassium and phosphoric acid. 


Whether these mineral substances are integral constituents of the proteid 
molecule, or closely adherent impurities, is a matter of doubt; the latter 
supposition is the more probable, as there are certain methods of obtaining 
proteids practically free from ash. The best of these is Harnack’s,® in which 
he precipitates the proteid as a copper albuminate ; this is dissolved in sodium 
hydrate, and the proteid is precipitated from this solution by hydrochloric acid. 
The so-called ash-free albumin obtained earlier by Aronstein and Schmidt ® by 
means of dialysis, was shown by later observers (Heynsius, Winogradoff) to be 
poor in ash, but not free from ash, and, moreover, that its incoagulability by 
heat and other characteristic properties were due to the use of alkali in its 
preparation. Nevertheless, Harnack’s ash-free albumin is also not coagulable 
by heat, and more closely resembles acid albumin in its properties than any 
other known proteid.” 


1 A very suggestive article by Pfliiger on this subject will be found in Arch. f. d. ges. 
Physiol., Bonn, Bd. xlii. S. 144. 

2 «Handbuch d. physiol. path. chem. Anal.,” 1885, 5th edition, S. 258. 

3 Loc. cit. Kiihne and Chittenden’s analyses of peptones, which they give with reserve, 
lie considerably outside these limits, Zschr. f. Biol., Miinchen, 1886, Bd. xxii. S. 452. 

+ Gmelin, ‘‘ Handb. d. org. Chem.,” Bd. viii. S. 285. 
5 > Ber. d. deutsch. chem. Geselisch., Berlin, Bd. xxii. S. 3046; Bd. xxiii. S. 3745 ; Bd. xxv. 

. 204. ; 

6 Arch. f. d. ges. Physiol., Bonn, 1875, S. 1. 

7 Werigo, ibid., Bd. xlviii. S. 127. Harnack denies that his material is acid-albumin, 
in spite of the acid used in its precipitation. 


26 CHEMICAL CONSTITUENTS OF BODY AND FOOD: 


Globin prepared from hemoglobin is stated to be free from ash. It is 
perhaps hardly correct to say that the ash is an impurity, because it is 
extremely probable that in their native condition the actual proteid molecules 
are combined more or less loosely with inorganic substances. 

The process of incinerating has its drawbacks in determining the amount 
of ash in a proteid ; for in the heating, some of the sulphur of the proteid, and 
when phosphorus is present the phosphorus also, will be oxidised and form 
sulphuric and phosphoric acids respectively. H. Schulz! has recently shown 
that sulphates are formed in tissues as a result of drying them at 110° C. ; this 
would occur to a greater extent still at the temperature necessary for ignition. 


The sulphur in proteids is in the body normally burnt off as 
sulphuric acid, which leaves the body in the urme as sulphates. The 
ethereal hydrogen sulphates of the urine originate in the intestine, as a 
result of putrefactive changes in proteids,” and when putrefaction is 
hindered by the administration of large doses of iodoform in dogs, these 
products do not appear in the urine. 3 Kriiger* has shown that a part 
of the sulphur in proteids is present in a condition of stable combination, 
a part loosely combined; the latter is removed by boiling with alkalis, 
the former is not; the proportions of the two differ in different proteids. 
Among the primary decomposition products of proteid, thio-acids, of 
which thioglycollic acid is probably the most abundant, are obtained.® 


From the elementary analyses which have been made of proteids, various 
observers have attempted to construct an empirical formula for certain typical 
proteids, egg-albumin being the one usually selected. Thus Lieberkiihn 
assigned iS alana the formula Crabbe Ny s0..8 ; Loew® gives the same 
formula ; Harnack” gives C,9,HsooN oO ggSo 5 Schiitzenberger,8 aig Hane ees 
S,; and ‘there have been others. The great divergence between these numbers 
requires no comment. 

Equally conflicting results have been obtained in attempts to ascertain the 
molecular weight of albumin. Lieberkiihn, in 1852, attempted to establish it 
by analysing the copper compound of egg-albumin; more recently, Harnack 
has done similar work. But very little importance can be attached to 
such work at present, for Chittenden and Whitehouse® find there is no 
definite copper albuminate, but that there are several in the mixture; and 
equally variable results are obtained with other metals both with egg albumin 
and myosin. 


Such researches lead to the same conclusion as dialysis, namely, that 
YSIS, y> 

the molecules of proteid are extremely large, but leave us quite im the 

dark as to their exact magnitude.!° It is possible that in the future the 


1 Arch. f. d. ges. Physiol., Bonn, 1894, Bd. lvi. S. 203. See also Halliburton and Brodie, 
Journ. Physiol., Cambridge ‘and London, 1894-95, al Xvi. p. 154. 

; Daumann, “Sischr. Ff. physiol. Chem., Strassburg, Bd. x. S. 123. 

3 Morax, ibid., S. 318. See also more recently ‘Nuttall and Thierfelder on ‘Animal 
Life without Bacteria in the Alimentary Canal,” dbid., vol. xxi. p. 109; xxii. p. 62. In this 


paper it is shown that healthy animal life is possible without micro-organisms in the 
alimentary canal. 


4 Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xliii. S. 244. 

°F. Suter, Zischr. f. physiol. Chen., Strassburg, 1895, Bd. xx. S. 564; E. Baumann, 
tbid., S. 583, and Virchow’s Archiv, 1894, Bd. exxxviii. S. 560 ; E. Salkowski, ibid., S. 562. 

§ Loew and Bokorny, ‘* Die chemische Kraftquelle im lebenden Protoplasma,” Munich, 
1882. 

7 Ztschr. f. physiol. Chem., Strassburg, Bd. y. S. 207. 

8 Bull. Soc. chim., Paris, Sér. 5, tomes xxiii. and xxiv. See also Schmiedeberg, Arch. f. 
exper. Path. u. Pharmakol., Leipzig, 1897, Bd. xxxix. S. 1. 

® Stud. Lab. Physiol. Chem., New Haven, vol. ii. p. 94. 

” The large size of the proteid molecule can be very strikingly demonstrated by the fact 


naa 


COMPOSITION OF THE PROTEIDS. 27 


result will be achieved, when proteids obtainable in a crystalline form 
have been thoroughly investigated. 

Vegetable proteids have been prepared in a crystalline form? in 
combination with magnesia; Drechsel? found in one preparation 1°4 per 
cent. of magnesia (MgO); in another, prepared by an improved method, 
1-43 per cent. From this the molecular weight 2 may be calculated as 
follows :— 

z 100-143. 
AQ OR 

From the similar examination of the sodium compound the mole- 
cular weight of albumin was found to be 1496. Other vegetable pro- 
teids examined by Griibler® also gave high but variable molecular 
weights. 

Hemoglobin belongs to the proteid compounds capable of crystallisa- 
tion; Zinoffsky * prepared hemoglobin crystals from the blood of the 
horse in a very pure state, and the formula calculated for hemoglobin 
from his elementary analyses would be— 


CreHzo.N Ons Fes, 


If a molecule of hematin, C,,H,,N,O,Fe, is subtracted, the formula for 
proteid left is— 


ard 


CesoHrosgN 10520201 
Jaquet’s® formula for pure hemoglobin of dog’s blood would give the 
proteid molecule a formula — 


1 NT ‘e! 
CrosHiaN 192930 v4 


So that here again there are great discrepancies. 

Such a summary of the principal analyses made, is quite sufficient to 
give point to Drechsel’s conclusion, that while divergences of analysis 
exist, even though they are due to extremely small errors, it is futile 
to attempt to measure accurately the size of the proteid molecule. 
Drechsel points out that in so large a molecule an analytical error of 
0-01 per cent. would have the same importance as one of 01 per cent. in 
ordinary analyses. 

It should be added, in conclusion, that some few investigators have 
used the eryoscopic method in attempting the solution of this problem ; 
the molecular weight of egg-albumin by this method is 14,000 
(Sabanejeff),® of albumoses 1200-2100, and of antipepton much less 
(Paal).7 

Equally ineonelusive, though much more interesting, have been the 
attempts to discover the rational formula for the proteid molecule. The 


that proteids in solution will not pass through a membrane of gelatin or silicic acid, when 
filtered under pressure. The products of proteolysis (proteoses and peptones) will, 
however, pass such a membrane ; the smaller size of their molecules has also been demon- 
strated by the cryoscopic method. Crystalloids pass through such membranes at the same 
rate as water, and can thus be easily separated from colloids in a solution containing both 
(C. J. Martin, Journ. Physiol., Cambridge and London, 1896, vol. xx. p. 364). 

1 The subject of vegetable and crystalline proteids will be treated at length in a later 
section of this chapter. 

2 Journ. f. prakt. Chem., Leipzig, 1879, N.¥., Bd. xix. S. 331. 

3 [bid., 1881, Bd. xxiii. S. 97. 

4 Zischr. f. physiol. Chem., Strassburg, 1885, Bd. x. S. 16. *Inaug. Diss., Basel, 1889. 

8 Ber. d. deutsch. chem. Gesellsch., Berlin, 1891, Bd. xxiv. Ref. 558. 

7 Thid., 1894, Bd. xxvii. S. 1827. For Siegfried’s work on the identity of antipeptone 
hee a simple compound, which he has called carnic acid, see under ‘‘ Chemistry of Muscle,” 
p- 103, 


28 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


usual method which a chemist follows in attempting to unravel the 
constitution of any substance, is first to discover the way in which it decom- 
poses (analysis), and then to build up the original material once more from 
the sinrple compounds so obtained (synthesis). In the case of the proteids 
there have been many observations on the analytical side, but synthesis 
has not yet been successful. We will first consider the results of 
analysis, next the attempts at synthesis, and finally state some of the 
theories founded on these observations. 

The decomposition products of proteids.—The experiments which 

have been performed fall into two 

—-, main groups: the first, designed with 
a view to determine the series of 
changes a proteid undergoes in its 
passage through the body; the second, 
with the object of investigating the 
chemical substances obtaimed as 
cleavage products by artificial means 
in the laboratory. In the first group 
the progress which has been made 
is shght, great and obvious difficulties 
being encountered at nearly every 
step; the end _ products, carbonic 
anhydride, water, urea, uric acid, 
ammonia, ete., are known, but the 
intermediate substances, resulting 
— from metabolic changes within the 

Fic. 7.—Leucine erystals.—After Kihne. cells and tissues, are still in the 

region of conjecture. 

In the alimentary canal itself there are, however, changes which are 
within the grasp of the investi- 
gator, and the proteoses, al- 
buminates, and peptones there 
formed will be treated under 
the head of “ Digestion.” Here, 
too, under the prolonged action 
of the pancreatic juice, simpler 
nitrogenous substances, such 
as leucine, tyrosine, aspartic 
acid, and ammonia, are formed 
in small quantities. Leucine 
(C,H,,N,0) is empirically 
amido-caproic acid, but of the 
numerous possible isomerides 
which could be included under 
that name, leucine has 
been shown to be a-amido- 
isobutylacetic acid, (CH,),CH. 
CH, CH, (NH,) COOH. The 
leucine obtained on pancreatic 
digestion is  dextrorotatory. 
Levorotatory and optically in- 
Fic. 8,—Tyrosine erystals.—After Frey. active varieties of leucine exist, 

and some of them haye been 


irc 


a 


THE DECOMPOSITION PRODUCTS OF PROTEIDS. 29 


prepared synthetically.!. Tyrosine (C,H,,NO,) is oxyphenyl amidopropionic 
acid, HO.C,H,.C,H,(NH,).COOH. This substance has also been made 
synthetically 2 2 The crystalline for ms of these two substances are seen in 
the accompanying figures (Figs. 7 and 8). Aspartic or asparaginic acid ® 
(C,H,NO,) is amido-succinic Shae C,H.(NH,)(COOH),. That ammonia 
is produced in prolonged pancreatic digestion, under conditions preclud- 
ing the possibility of putrefaction, was shown by Stadelmann.4 

To this list must be added lysine, lysatinine, arginine® (see p. 
33), glutaminic acid, and proteinchromogen, a substance of un- 
certain nature which gives a reddish-violet product with chlorine or 
bromine water. 

Within the intestine many changes occur which are due to bacterial 
action. The products which have just been enumerated arise first, 
and then by different changes other substances are formed; of these 
the following may be mentioned :—indol, skatol, skatol-carbonic acid, 
oxyphenyl propionic acid, phenylpropionie, and phenylacetic acids, 
parakresol, and phenol, and simpler bodies like carbonic anhydride, 
water, ammonia, hydrogen, and sulphuretted hydrogen, amido-fatty acids, 
and fatty acids themselves.’ The most interesting point to note here 
is the large number of derivatives containing the benzene nucleus. The 
indol group has never been obtained from the proteid molecule by any 
other method than that of bacterial decomposition.® 

We can now pass to the second category of investigations, namely, 
those carried out i vitro. 

The first action produced by most reagents, especially if they bring 
about hydrolysis, is the formation of proteoses and peptones; these are 
then broken up into more simple substances. The subject may be most 
conveniently treated of under the heads of the different methods employed. 

1. Treatment with alkalis—Maulder® treated albumin with caustic 
potash, and obtained the substance which we now call alkali-albumin ; 
this material is free from most of the sulphur present in the original 
proteid, namely, that which is present in loose combination; the firmly 
combined sulphur, however, remains undisturbed.!® 

Mulder thought that by this method he had obtained the base of 
all albuminous material, and called it “protein”; he described many 


1 For recent literature on leucine, see Schulze and Likiernik, Ztschr. f. physiol. Chem. 
Strassburg, Bd. xviii.; Gmelin, ibid., Bd. xviii.; Hiifner, ‘‘ Synthesis of Leucine,” Journ. f. 
prakt. Chem., Leipzig, N. F., Bd. 1.5 E. Schulze, Barbieri and Bosshard, Ztschr. J. physiol. 
Chem., Strassburg, Bde. ix. and x. : Cohn, ibid., Bd. xx. 

? Erlenmeyer and Lipp, Ber. d. deutsch. chem. Geselisch., Berlin, Bd. xy. S. 1544. 

* For chemistry and preparation, see Hlasiwetz and Habermann, Ann. d. Chem., 
Leipzig, Bd. clxix. S. 160; E. Schulze, Ztschr. f. physiol. Chem., Strassburg, Bd. ix. 

4 Zischr. f. Biol., Miimchen, 1888, Bd. xxiv. 8S. 261. See also Hirschler, Zéschr. f. 
physiol. Chem., Strassburg, Bd. x. 8. 302. 

° Hedin, Arch. f. Physiol., Leipzig, 1891, S. 273. 

§Stadelmann, Zschr. f. Biol., Miinchen, Bd. xxvi. S. 491. Neumeister suggests the 
name tryptophan. for this substance, ibid., S. 324 ; ; Nencki, Ber. d. deutsch. chem. ‘Gesellsch.., 
Berlin, Bd. xxviii. S. 560. 

7 Salkowski, ibid., Bd. xii. S. 648; Tappeiner, Zéschr. f. Biol., Miinchen, Bd. xxii. 
8. 236. 

8 For recent work on the mycological processes in the intestines, see V. D. Harris, 
Journ. Path. and Bacteriol., Edin. and London, 1895, vol. iii. p. 310. On the putrefaction 
of pure proteids see O. Emmerling (Ber. d. deutsch. chem. Gresellsch., Berlin, 1896, Bd. xxix. 
S. 2721) ; in addition to the substances enumerated above he finds betaine. 

® Journ. f. prakt. Chem., Leipzig, Bd. xvi. S. 129; Bd. xvii. S. 312; Ann. d. Chem., 
Leipzig, Bd. xxxi. S. 129. 

_  Kriiger, Arch. f. d. ges. Physiol., Bonn, Bd. xliii. S. 244. 


30 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


compounds of this substance, but, as Liebig’ was the first to show, 
this work was full of fallacies, and the only remnant of it is the survival 
of the word proteid. 

Pavy? has used caustic potash in his researches on proteids, and 
shown that the action of the alkali is to split off a substance of an amylose 
nature which, on further treatment with mineral acids, yields a reducing 
but non-fermentable sugar, C,H,,0,, which gives a crystalline osazone 
with phenylhydrazine. Pavy, however, himself points out that he is 
not the first to obtain this result. Schiitzenberger* many years ago 
obtained from proteid a dextrin-like substance by the prolonged use 
of baryta water, which, after treatment with sulphuric acid, reduces 
Fehling’s solution, and “appears to be glucose, or an analogous substance.” 
From his own and Schiitzenberger’s work, he draws the conclusion that 
proteid matter has the constitution of a glucoside. These experiments 
will be Sou referred to under the gluco-proteids. 

O. Nasse * discovered that by boiling proteids with a strong solution 
of barium hydrate some of their nitrogen was disengaged as ammonia, 
but this only accounted for a small percentage of the total nitrogen. 
He concluded that the nitrogen which is readily liberated is in the form 
of an amide, that some is combined similarly to that of creatine, but that 
the major part which is unaffected by this treatment is in the form of 
an amido-acid. 

Schiitzenberger® has elaborated the baryta method. He obtained dif- 
ferent results by varying the conditions of temperature and pressure, of 
the time of treatment, and of the amount of barium hydrate employed. In 
his earlier researches he employed coagulated egg-w ‘hite, which had been 
thoroughly washed with water, alcohol, and ether ; weighed amounts of 
it were treated with from two to six times their weight of crystallised 
barium hydrate and with water, the whole being heated in a closed iron 
vessel to temperatures ranging from 100° to 250° C., and for periods of 
time varying from 8 to 120 ‘hours. He found that nitrogen to the extent 
of about one per cent. of the total weight of albumin is given off as 
ammonia at atmospheric pressure, by boiling for half an hour; a second 
one per cent. comes off slowly by continued boiling for 120 hours (this 
result is, however, more easily obtamed by treating with three parts of 
barium hydrate at 120° C. for six to eight hours); a third one per cent. is 
given off by treating with two parts of barium hydrate at 150° C., and a 
fourth one per cent. by heating with excess of barium hydrate at 260° C. 

He next found that accompanyig these four stages there were 
different cleavage products obtamed. First, some insoluble barium salts, 
namely, oxalate, carbonate, phosphate, and sulphate. On calculating 
the quantities of oxalate and carbonate formed, he arrived at the 
interesting result that they were present in proportions to support the 
hypothesis that, with the ammonia set free, they had existed in the pro- 
teid molecule as a urea and oxamide radicle. The barium carbonate 
and oxalate, moreover, were formed at different stages of ammonia 


1 Ann. d. Chem., Leipzig, Bd. lxii. 8. 132. 

2 «Physiology of the Carbohydrates,” London, 1894, p. 28; Proc. Roy. Soe. 
London, 1893, vol. liv. p. 53 ; Rep. Brit. Ass. Adv. Se., London, 1896. 

3 Bull. Sov. chim., Paris, 1875, Sér. 5, tome xxiii. p. 161. 

4 Chem. Centr.-Bl. Leipzig, 1873, S. 137; Arch. f. d. ges. Physiol., Bonn, Bde. vi. S. 
589 ; vii. S. 139 ; vili. s. 381. 

5 Ann. de chim., Paris, Sér. 5, tome xvi. p. 289 ; Compt. rend. Acad. d. sc., Paris, tome ci. 
ps L267 sicis p: 289 ; cvi. p. 1407 ; ; CXli. p. 189; Bull. Soc. chim., Paris, Sér. 5, tome xxiv. 


THE DECOMPOSITION PRODUCTS OF PROTEIDS. 31 
elimination, in such a way that the first amount of ammonia might be 
considered to come from one of the amide radicles of the oxamide, while 
the second corresponded to the urea, and the third to the remaining 
nitrogen of the oxamide, then present as oxamic acid. 

After precipitating the barium with carbonic anhydride and sulphuric 
acid, he obtained, by distillation in a partial vacuum, a small quantity of 
acetic acid, traces of formic acid, and an essential volatile oil which he 
indentified as pyrrol contaminated with smaller quantities of methyl- 
pyrrol and ethyl-pyrrol. The remainder, which did not volatilise 
nor sublime at a low temperature, he termed résidu fixe. By con- 
trasting the composition of this with that of the original albumin, 
and taking into account the substances already enumerated, he found 
that the essential action of the barium ‘hy drate was that of 
hydrolysis. By repeated crystallisations from water, alcohol, and 
ether, he separated the constituents of his résidu fixe and found 
they were amido-acids of two classes, which we may term 4 and B. 

A. These oagersed over 80 per cent. of the total weight; in them 
the proportion N:0=1:2. They consisted of— 

1. Amido-acids of the series C aseeriee 

These he called leucines. They included alanine (C=3) in small 
quantities, propalanine or amidobutyric acid (C=4), butalanine or 
amidovaleric acid (C=5), both in considerable amount, and leucine or 
amidocaproic acid (C=6), in very large quantities. Glycocine or amido- 
acetic acid (C= 2) was not found. 

2. Amido-acids of the series C,,H,,,_,N.O. 

These are amido-acids of the acrylic series, and were called leucéines. 
Here, too, the term which was most abundant is that in which C=6, but 
bodies corresponding to C=4 or 5 were also found. 

3. Amido-acids of the series C,H,,N,O,, or some multiple of this. 
To these substances he gave the name of gluco-proteins, on account 
of their sweet taste. The most abundant of these were those in which 
C=9 or 7, or some multiple of these numbers; but others in which 
C=8, 10, and 11 were also isolated. 

b. These comprised about 16 per cent. of the total weight; in them 
the proportion N:O = 1:5, or 1:4, or 2:5. In this class were found— 

1. Tyrosine; the amount of this was about 3-5 per cent. 

2. Tyroleucine, C,H,,NO,, in about the same quantity. 

3. Very small quantities of glutaminic acid, C,H,NO, This is an 
optically imactive amido-derivative of one of the pyrotartaric acids 
(glutaric). 

Of these substances, Schiitzenberger found varying quantities, 
according to the degree to which the hydrolytic decomposition had been 
carried out. The more thorough the hydrolysation, the more leucines 
and leucéines were found; but in earlier stages gluco-proteins were 
in excess. 

With other proteids he obtained corresponding results. Gelatin 
gave the same substances, with the addition of amido-acetic acid or 
glycocine ; 20 to 25 per cent. of this substance was obtained. 

He concluded that the albumin molecule, under the action of barium 
hydrate, loses ammonia, carbonic anhydride, acetic and oxalic acid, and, 
becoming hydrated, forms in the first instance gluco-proteins, mainly 
those in which C=9, or some multiple of this, and that on further action 
these are changed into leucines and leucéines. 


32 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


2. Treatment with acids—Prolonged heating of proteids with dilute 
acids results in their hydration and the formation of proteoses and 
peptone.! Strong acids produce the same effect at the ordinary tempera- 
ture in the course of a few days. This method has the disadvantage 
that strongly coloured materials make their appearance, and to avoid 
this Hlasiwetz and Habermann ® introduced the important modification 
of heating with strong hydrochloric acid and stannous chloride, by which 
pale yellow solutions were obtained without a trace of charrmg. <A 
certain amount of reduction occurred during the operations, leading to 
the formation of stannic chloride. These methods yielded the following 
substances :— 

(1) Ammonia; (2) an amido-acid of the acetic series, namely, leucine ; 
(3) two amido-acids of the acrylic series, namely, asparagiic acid 
(C,H.NO,, amido-succinic acid), and glutaminie acid (C;H,NO,, amido- 
pyrotartaric acid), both in considerable amount; (4) tyrosine or 
oxyphenylalanine. 


Ritthausen * was the first to separate glutaminic acid and asparaginic acids 
from proteids. He and Kreusler suggested that glutaminic acid was a typical 
product of vegetable proteid ; but Hlasiwetz and Habermann ® obtained it from 
casein, albumin, and other animal proteids. The glutaminic acid they isolated 
was levorotatory, while that obtained by Schiitzenberger was only found in 
small quantities and was optically inactive. By boiling the active form with 
barium hydrate, however, it is converted into the inactive form, and further, 
the inactive form if allowed to ferment under the action of the mould 
Penicillium glaucum, is transformed into the optically active modification.® 

Employing the same method, Horbaczewski’ obtained leucine, glutaminicacid, 
and glycocine from gelatin, but no asparaginic acid or tyrosine. Hofmeister,§ 
however, obtained small quantities of asparaginic acid. 

From elastin were obtained ammonia, leucine, tyrosine, glycocine, butalanine 
(C;H,,NO,, amido-valeric acid), but no glutaminic or asparaginic acids.® 

From reticulin (a substance separated from reticular tissue) were obtained 
ammonia, sulphuretted hydrogen, and amido-valeric acid, but no tyrosine or 
glutaminic acid (Siegfried). : 


By the employment of the same method, Drechsel?® has discovered two 
new substances, which are of special interest. He began by studying 
the quantities of nitrogenous bodies which other observers had obtained ; 
and if he assumed that only one-half of these had been isolated there 
still remained about 30 per cent. of the nitrogen of the proteid to be 
accounted for. He pointed out also that Schiitzenberger obtamed 
carbonic anhydride by his method, and that Hlasiwetz and Habermann 
did not by theirs. He argued from this that there should be some other 


1 Neumeister, Zéschr. f. Biol., Miinchen, Bd. xxiii. 8. 381. 

2 See Brodie, Science Progress, London, 1895, vol. iv. p. 67. 

3 Ann. d. Chem., Leipzig, 1873, Bd. clxix. 8. 150. In a paper published previous to 
this by the same observers (zbid., Bd. clix. S. 304), they sought unsuccessfully to establish a 
definite relationship between proteids and carbohydrates. 

4 Journ. f. prakt. Chem., Leipzig, Bde. xcix. S. 454 ; evii. S. 218. 

5 Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1872, Bd. ix. S. 114. 

6 Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. xvii. S. 388. Similar changes in the 
optical varieties of leucine and other substances are similarly produced. 

7 Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1880, Abth. 2, Bd. xxx. S. 101. 

8 Zitschr. f. physiol. Chem., Strassburg, Bd. ii. S. 299. 

9 Horbaczewski, Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1886, Abth. 2, Bd. xcii. 
S. 657. 

10 «Der Abbau d. Eiweissstoffe,” Arch. f. Physiol., Leipzig, 1891, S. 248. 


———<x«—<= Srl swt 


THE DECOMPOSITION PRODUCTS OF PROTEIDS. 33 


substance produced by the latter method, which should yield carbonic 
anhydride on treatment with an alkali. As he considered it probable 
that this substance might be basic, he endeavoured to isolate it as a 
precipitate by means of phosphotungstic acid, a reagent which is of 
great value as a precipitant of basic or alkaloidal bodies. By this means 
he succeeded in isolating not one but two bases, which he named /ysine 
and lysatinine. 

Lysine has the formula C,H,,N,O,, and is homologous with Jaffe’s? 
ornithin (C,;H,,N,O,, probably diamidovalerianic acid). Lysine is pro- 
bably diamidocaproic acid. On heating it to 120°-130° with barium 
hydrate, barium carbonate is formed. It will therefore account for some 
of Schiitzenberger’s carbonic anhydride. 

Lysatine or lysatinine, the second base, is even more interesting. 
Its formula is either C,H,,N,O, or C,H,,N,O, and is a homologue of 
either creatine (C,H,N,O,) or creatinine (C,H,N,O), according as the first 
or second formula is taken. 

It can be obtained pure as a double salt of its nitrate with silver 
nitrate, and this when boiled with barium hydrate for twenty-five 
minutes yields urea; this is a decomposition exactly analogous to that of 
creatinine under the same circumstances. From 10 grms. of the 
double salt Drechsel obtained about 1 grm. of urea; which is a large 
quantity when one considers that under the conditions urea is quickly 
broken up into ammonia and carbonic anhydride. 


This is the first time that urea has been obtained from proteid in laboratory 
experiments. Many years ago, Béchamp? stated that he had obtained urea 
from egg-white by the oxidising action of potassium permanganate. Lossen ® 
found that the substance Béchamp took for urea was guanidine, which 
probably came from small quantities of xanthine, present in the egg-white as 
an impurity, or, as Drechsel* points out, from lysatinine. Drechsel’s method, 
it is important to notice, is one of hydration; not, like Béchamp’s, one of 
oxidation.°® 

It should be added that Drechsel’s work was carried out in the first 
instance with casein, but his pupils have discovered lysine and lysatinine 
among the cleavage products of other proteids and proteid-like substances,® 
and further that the same substances are formed during pancreatic digestion.’ 

Hedin ® has more recently arrived at the conclusion that lysatinine is not 
a chemical individual, but a mixture of lysine with another base called 
arginine. Arginine (C,H,,N,O,) was originally separated from vegetable 
tissues by Schulze and Steiger,? and subsequently it was found by Hedin !° 


1 Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. x. 8. 1925. 

2 Ann. d. Chem., Leipzig, 1856, Bd. 100, S. 247. 

3 [bid., 1880, Bd. 201, S. 369. Between Béchamp’s and Lossen’s time the question was in- 
vestigated by Stiideler, Journ. f. prakt. Chem., Leipzig, 1857, Bd. Ixxii. S. 251; Loew, iid., 
1871, N.F., Bd. iii. S. 289 ; Tappeiner, ibid., 1871, Bd. civ. S. 408 ; and Ritter, Compt. 
rend. Acad. d. sc., Paris, tome lxxiii. p. 1219 ; all of whom except Ritter failed to confirm 
Béchamp’s results. 

4 Loc. cit. 

5 On the formation of urea by oxidation from many organic substances, see F, Hofmeister, 
Arch. f. exper. Path. u. Pharmakol., Leipzig, 1897, Bd. xxxvii. S. 426. 

6 Fischer (from gelatin), Inaug. Diss., Leipzig, 1890; Arch. f. Anat. u. Physiol., Leipzig, 
1891, S. 205. Siegfried (from conglutin), Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. xxiv. 
S. 418 ; (from reticulin), ‘‘ Ueber d. chem. Eigeuschaften des retic. Gewebes,” Habilitation- 
schrift, Leipzig, 1892. Siegfried also obtained from conglutin a sweet substance 
(C,H,,N.O,), corresponding to one of Schittzenberger’s gluco-proteins. 

7 Hedin, Joc. cit. 8 Ztschr. f. physiol. Chem., Strassburg, 1896, Bd. xxi. S. 297. 

9 Ibid., Bd. xi. S. 43; Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. xxiv. S. 2707 ; 1896, 
Baexxix S352. 

W Zischr. f. physiol. Chem., Strassburg, Bd. xx. S. 186; xxi. S. 155; xxii. $.191. 

VOL. I.—3 


34 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


to be a constant decomposition product of proteids and albuminoids. It 
yields urea on treatment of its silver salt with barium hydrate. 

Other recently published work on the decomposition of proteids by 
hydrochloric acid is by R. Cohn.! He used concentrated acid, and no 
stannous chloride. From 1000 parts of casei he recovered 916°75 of 
products ; these consisted of fatty acids, 34°25 ; tyrosine, 35; leucine, 321; an 
oily product containing an acid, C,H,.N.O,, 180; pyridine derivatives, 3°65 ; 
other substances, including cystin, cystein, thiolactic acid, and Drechsel’s bases, 
the remainder. 


3. Treatment with oxidising agents. — Treatment of proteids with 
nitric acid yields, first, an insoluble yellow substance of uncertain 
composition, called xanthoproteic acid; this dissolves gradually, and 
finally paraoxybenzoic acid (probably from the oxidation of tyrosine), 
oxalic, fumaric, and saccharic acids are formed. 

Oxidation by manganese dioxide or potassium bichromate, with 
sulphuric acid, has yielded —(1) Fatty acids, from formic up to caprylic 
(G20): and their aldehydes; (2) nitrates of acetic, propionic, valerie, 
butyric, and hydrocyanie acids; (5 benzoic acid and benzoic aldehyde. 
Oxidation with chlorine water has yielded, among other products, fumaric 
acid, oxalic acid, and chlorazol. Oxidation with bromine water at high 
temperatures in a sealed tube has yielded carbonic anhydride, oxalic 
acid, ammonia, bromanil (C,Br,O,), bromoform (CHBr,), monobrom- 
benzoic acid, mono- and dibromacetic acids, tribromamidobenzoie acid 
(C,HBr. (NH)COOH), asparaginic and malaminic acids, leucine and 
leucimide (C,;H,,NO). No tyrosine was obtained.* 

4. Treatment by action of heat.—Dry distillation leads to the forma- 
tion of a complex oily material, called “ Dippel’s oil,” which contains 
a large number of substances: among these are hydrocarbons of the 
fatty series, ammonium salts of fatty acids, nitrates and ketones of the 
same series, carbonic anhydride, ammonia, amines of fatty acid radicles, 
hydrocarbons and amines of the benzene series, aniline and its 
homologues, phenol and its homologues, members of the pyridine 
group of bases, namely, Py ridine (C,; ILN.), picoline (C,H,N), lutidine 
(C,H,N), and collidine (O,H,,N), and lastly, pyrrol. 


Some of the substances last mentioned will also be found in our list of the 
animal alkaloids (p. 59); here we have direct proof that proteid substances 
have within them, or are capable of forming by intramolecular rearrangement, 
basic bodies of this nature. The pyridine bases have, moreover, been shown 
to take a part in the formation of the vegetable alkaloids, piperidine, 
cinchonine, ete. 


It is extremely probable that proteids contain within their molecule 
a radicle of the closed ring series, but even if they do not, there still 
remains the possibility that by the action of heat, substances with 
open carbon chains may be transformed into those with closed rings. 
The following example is selected by Brodie 4:— 


1 Ztschr. f. physiol. Chem., Strassburg, 1896, Bd. xxii. 8. 153. 

2? Baumann, Ber, d. deutsch. chem. Gesellsch. , Berlin, Bd. xii. 8S. 1453. 

3 Hlasiwetz and Habermann, Ann. d. Chem., Leipzig, 1871, Bd. clix. S. 304. Blennard, 
Compt. rend. Acad. d. sc. , Paris, tome xe. p. 612; xcii. p. 458. This latter observer also 
obtained gluco-proteins. 

4 Loe. cit. 


a 


THE ATTEMPTED SYNTHESIS OF PROTEIDS. 35 


At 190° dry glutaminie acid is converted into pyroglutaminic acid, 
Jd ; ee Gee) 
and at a higher temperature this, in turn, is converted into pyrrol. 


COOH OOH CH:CH 
vs A Hi 

CH,——CH.NH, CH,—CH ‘NH 
| ; 

CH,—COOH. | ‘NH |  CH:CH | 
4 | | 
| Za 

(glutaminic acid) © CO (pyrrol) 


(pyroglutaminic acid) | 


The attempted synthesis of proteids.—Since Wohler in 1828 
succeeded in making urea artificially from its elements, the strides 
that organic chemistry has made have been prodigious. Complex 
substances, previously made only in the living laboratory of plants 
and animals, are now manufactured daily in the test tubes and retorts 
of the chemist. The substances of most importance to vital processes, 
the carbohydrates and the proteids, have been among the last to yield 
before this advance, but we have seen how sugar has given way to 
Fischer; and there are signs that the last conquest of organic chemistry, 
the synthesis of proteids, cannot be far distant. I propose to sketch one 
or two of the principal attempts that have been made in the manu- 
facture of albuminous from simpler substances. 

Schiitzenberger’s experiments.—We have already seen that the pro- 
ducts of decomposition of a proteid are extremely numerous, but briefly 
they fall into two principal groups, the fatty compounds (generally con- 
taining an amidogen radicle) and the aromatic compounds or derivatives 
of benzene. To Schiitzenberger 2 2 belongs the credit of an attempt to 
build up from some of the compounds he had shown could be obtained 
from albumin, something like the original proteid. 

In order to effect the synthesis of proteid material, he considered it 
necessary to combine a molecule of a leucine (7.e. an amido-fatty acid) 
with a molecule of a leucéine (an amido-acid of the acrylic series), with 
elimination of water, and then to combine this complex group with one 
or more molecules of urea and oxamide, also with the elimination of 
water. We have already seen that the method he had adopted for the 
breaking up of proteids ith alkali—leads to hydrolysis; so in 
any attempt at synthesis he recognised as a sine qua non the necessity 
of some method of dehydration. 

The provisional formula he gives is the following :— 


HCO 2 NEL 38Cs be NO io, Cal... NO} 
with elimination of eight molecules of water. This would give 
Ca aellin, aN Oa, a 1g — 28. 


the percentage composition calculated from the formula agrees closely 
with that of albumin. 


1 Bernheimer, Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. xv. S. 1222 
2 Compt. rend. Acad. d. sc., Paris, tome evi. p. 1407 ; exii. p. 198, 


36 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


Accordingly, amido-compounds, leucines (C,,H;,,,,;NO.), and leucéines 
(C,H,,_;NO.), were mixed with about 10 per cent. of urea, and finely 
powdered. The mixture was dried at 110° C., intimately mixed with 15 
times its weight of phosphoric anhydride, and heated in an oil bath. At 
120° C. there is no change; at 125° dehydration takes place rapidly, and 
the mixture becomes pasty, but solidifies to a compact solid mass without any 
darkening. This is dissolved in water, the solution mixed with excess of 
alcohol, and the pasty precipitate so produced washed with alcohol and 
re-dissolved in water. Phosphoric acid is removed by baryta, and the filtered 
liquid when concentrated yields an amorphous product soluble in water, but 
precipitated in a curdy form on the addition of alcohol. 

Aqueous solutions of this product are precipitable by most of the other preci- 
pitants of proteids ; it gives the biuret and the xanthoproteic reactions. When 
burnt it gives the characteristic odour of burning nitrogenous animal matter. 


The product he obtained does not give all the proteid reactions; 
it is, for instance, not precipitable by acetic acid and ferrocyanide of 
potassium ; and the evidence as to its proteid nature is otherwise hardly 
conclusive, because the colour tests for proteids are given by many of 
the decomposition products of albuminous matter. The partial success 
obtained will, however, point the way for future attempts, and so far 
as it goes, is in favour of Schiitzenberger’s ureide theory of proteid 
constitution. Complete success could hardly have been anticipated 
from such an experiment, because no means were taken to ensure the 
presence of sulphur, an element present in all proteids. Moreover, 
in the synthesis, no aromatic substance was introduced; this, how- 
ever, is not absolutely necessary, as the formation of aromatic from 
fatty compounds by heat is a familiar chemical change (see p. 34). 

Grimaux’s experiments.—Some years previous to Schiitzenberger’s 
work, Grimaux! had obtained, by somewhat simpler processes, substances 
which even more resembled proteids in their reactions than Schiitzen- 
berger's. He was engaged in studying the properties of certain sub- 
stances, inorganic and organic, which he termed “ colloides,” and of those 
which he prepared the three which especially bear on the present 
question are the following :— 

(4) Colloide amidobenzoique-—This is made by heating, to 125° C., 
meta-amidobenzoic acid in a sealed tube, with one and a half times its 
weight of phosphorus pentachloride, for ninety minutes. The product is 
a white friable powder; this is washed repeatedly with boiling water to 
remove all phosphoric acid. The remaining substance Grimaux supposes 
to be an intramolecular anhydride, formed by the union of several mole- 
cules of meta-amidobenzoic acid, with the elimination of water. When 
ammonia is added, it dissolves slowly in the cold, but rapidly on heating. 
The solution obtained is evaporated in vacuo, at a low temperature, and 
the resulting solid is a transparent jelly which dries into translucent, 
yellowish plates, which in their physical properties resemble dried 
serum albumin. 

(b) A colloid which is similarly prepared, except that the temperature 
in the sealed tube is allowed to rise to 135° C. 

(c) Colloide aspartique—This is made by the action of a current of 
gaseous ammonia on solid aspartic anhydride, heated to 170° C. The 


, Compt. rend. Acad. d. sc., Paris, tome xciii. p. 771; xevii. pp. 231, 1336, 1434, 1485, 
1540, 1578; Rev, scient., Paris, April 18, 1886; this article gives a summary of the other 
papers, 


SS Se ws - -”--~-~—-—— 


THE ATTEMPTED SYNTHESIS OF PROTEIDS. 37 


product is washed with water, and after evaporation im vacuo yields a 
substance similar in appearance to the colloid (@). 

In all three cases, heavy molecules were formed; and in all, the 
result was a colloidal substance, exhibiting many of the properties of 
proteids. In the case of the first two colloids, there was present not 
only the amidogen, but also the aromatic radicle. Although the result 
is not albumin, the resemblance between the physical properties and 
chemical reactions of proteids and of these synthesised colloids is 
remarkably close. Pickering! has fully confirmed Grimaux’s results, and 
has added new facts illustrating the points of similarity between them 
and proteids. 

The chief of these are as follows :— 

1. All give the xanthoproteic reaction. 

2. With copper sulphate and caustic potash, « gives a blue-violet ; 
b, nil; c, a typical violet coloration, like that given by albumin. 

3. Their solutions do not coagulate on heating in the absence of salt ; 
if, however, a trace of a soluble barium, strontium, or calcium salt is 
present, opalescence occurs at 56°, and coagulation at 75° C. 

4. The colloids are removed from solution (rising to the surface of 
the fluid) by saturation with magnesium sulphate, sodium chloride or 
ammoniun sulphate. Here they especially resemble the class of 
proteids called globulins. 

5, Another resemblance to globulins is seen in their behaviour to a 
stream of carbonic anhydride, which, in the presence of salts, causes 
precipitation. The passage of a current of air through the mixture 
redissolves the precipitate. 

6. The colloid 6 is not digested by pepsin-hydrochloric acid; @ is 
slightly digested ; ¢ is easily digested, and the solution gives the ty pica] 
peptone colour, pink, on the addition of copper sulphate and caustic 
potash. 

7. Any one of the three colloids, when intravenously injected into 
animals (rabbits, cats, dogs, rats, guinea-pigs) causes extensive intra- 
vascular coagulation. In a typical experiment death is due to respiratory 
failure. In this property of the proteid-like colloids, which was dis- 
covered by Pickering, they closely resemble the nucleo-proteids (see 
p. 67). The resemblance to the action of the nucleo-proteids extends 
even to minor points; for instance, neither cause intravascular clotting 
in albino rabbits ;? and in dogs very minute doses indeed, cause a slowing 
of the rate of coagulation (We ooldridge’s negative phase). 

The artificial colloids do not resemble nucleo- -proteids in promoting 
the formation of fibrin in solutions of fibrinogen. 

If nucleo-proteids and these colloids both produce the same effect in 
the same way, their physiological activity is probably connected with 
the presence of some radicle common to both. The colloidal condi- 
tion will not explain the action, simce most colloids do not act thus. 

1 Pickering, J. W., Journ. Physiol., Cambridge and London, vol. xiv. p. 347 ; xviii. 
p. 54; Pickering and Halliburton, zbid., vol. xviii. p. 285. More recently Pickering has 
succeeded in making several new proteid-like colloids (Proc. Roy. Soc. London, 1896, 
vol. lx. p. 337). 

2 This point has been worked out by Pickering also in the case of the Arctic hare. 
During the albino stage of the animal, neither nucleo-proteids nor synthesised colloids cause 
intravascular coagulation, but during their pigmented stage intravascular coagulation is 
produced in the usual way. The change i in the external appearance of the animal is thus 


associated with other changes in its constitution (Journ. Physiol., Cambridge and London, 
1896, vol. xx. p. 310). 


38 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


The active radicle cannot be one which contains phosphorus, since the 
synthesized colloids are free from that element. It may possibly be the 
amido- -fatty radicle in a high state of condensation. 


Lilienfeld and Wolkowicz,! by the condensation of amido-acid compounds, 
have obtained substances which resemble proteoses in their reactions. 


Theories of proteid constitution.—The views of Schiitzenberger 
on this subject will have been gathered from the preceding section. 
There now remain to be mentioned some other theories on the subject, 
which are in part deductions from the work of others, and partake 
more of the nature of speculation than of hypotheses that have been 
tested by experiment. 

Pjfliiger’s theory.—The distinction between non-living proteids and 
living protoplasm was noted as early as 1821 by Rudolphi,? who 
wrote: “The components of the dead and living body do not exist under 
the same chemical conditions.” A few years later the distinction 
between living and non-living proteids was emphasised by John 
Fletcher.® Piliiger’ s theory * was, however, the first intelligible one to 
explain such differences. The non- -living proteids, such as are contained 
in white of egg, are stable and indifferent to neutral oxygen; but when 
such proteids are assimilated—that is, become part of a living cell—the 
molecules live by breathing oxygen. The assimilation of a proteid is 
probably due to the formation of ether-like combinations between 
the molecules of living proteid and the isomeric molecules of the food 
proteid, water being eliminated ; this process of polymerisation produces 
large and heavy but still simple molecules; and during its occurrence 
the. nitrogen of the non-living proteid leaves the hydrogen with which it 
is combined in the form of amidogen (NH,), and enters into combination 
with carbon to form the much more unstable substance cyanogen (CN). 
We thus find uric acid, creatine, guanine, etc., as products of proteid 
metabolism, while none of such cyanogen-containing molecules are 
obtainable from non-living proteid. 


Pfluger’s theory was put forward in 1876; but in the light of Drechsel’s 
later work, the part involving exchange of nitrogen between cyanogen and 
amidogen is rendered unlikely, and with that the wholetheory must probably fall. 


Loew's theory.—The researches of Loew and Bokorny® have taken 
the same direction as those of Pfliiger, in that they are attempts to 
explain the distinction between living and dead protoplasm. Living 
protoplasm or proteid (in the cells of various algee) has the property of 
reducing silver from a weak alkaline solution of silver nitrate; dead 
proteid has no such effect; animal protoplasm is so quickly killed by 
silver nitrate, that it does not give the reaction. The conclusion 
formed is, that something of the nature of an aldehyde occurs in living 
protoplasm. Formic aldehyde i is probably formed in plants by the union 
of carbon and water; if this is united to ammonia, aspartic aldehyde is 
formed, thus :— 


1 Arch. f. Anat. u. Physiol., Leipzig, 1894, Physiol. Abth. S. 383 and 555. 

2 “*Grundriss der Physiologie,” 1821. 

° «Rudiments of Physiology,” Edinburgh, 1837 

4 Arch. f. d. ges. Physiol., Bonn, Bd. x. S. 251. 

5 «Die chem. Kraftquelle im lebenden Protoplasma,” Munich, 1882. Loew’s most 
recent views on this subject will be found in a recently published pamphlet, ‘“‘ The Energy 
of Living Protoplasm,” London, 1896. 


GENERAL PROPERTIES AND REACTIONS OF PROTEIDS. 39 
4CHOH+NH,= NH,.CH.COH+2H,0 


| 
CH,.COH 
By polymerisation of aspartic aldehyde we have— 
(NH..CH.COH) 
3 | P = Ce N,O.7 20.0 
| — cx,con| 


and by further polymerisation in the presence of a sulphur compound 
and hydrogen we get 


6C,,H,,N,0,+H,S+6H, = C.,H,.N .80»+2H,0 


which represents the composition of ordinary albumin. If such an 
aldehyde does exist in “living proteid” its instability is explicable, 
because molecular movements would be constantly occurring in the 
aldehyde group. 


The theory is ingenious, but an obvious objection to it is that it assumes 
the empirical formula above given for albumin to be the correct one. The 
theory has been adversely criticised by Baumaun! who points out that alde- 
hydes are not the only substances that reduce alkaline solutions of silver 
nitrate, but that many organic substances, such as pyrogallol, resorcin, hydro- 
chinon, pyrocatechuic acid, alloxan, and morphine do so also. It is stated, 
moreover, by Kretzschmar? and Griffiths,’ that both living and dead proto- 
plasm give the reaction. 


Latham’s theory.A—This is to some extent a combination of the two 
just described. Latham considers living proteid to be composed to a 
chain of cyanalcohols or cyanhydrins, as they are often called, united to 
a benzene nucleus. 

A cyanalcohol is a substance obtained by the union of an aldehyde 
with hydrocyanic acid; for instance— 

CH,.COH+HCN=CH,.CH(CN)OH 
(ethaldehyde) (hydro- (cyanethylic alcohol) 
cyanic acid) 

Other alcohols are formed from other aldehydes, and these are all 
united to one another and to benzene to form a proteid. 

Latham shows that the various products of the disintegration of 
albumin can also be obtained by the condensation and intramolecular 
changes that these cyanalcohols, which are exceedingly unstable 
substances, undergo. Instability and proneness to undergo intra- 
molecular changes are two properties common to “living proteids” and 
to cyanalcohols. 

General properties and reactions of proteids.—=Solubilities.— 
All proteids are insoluble in alcohol and ether. Some are soluble in 
water, others insoluble. Many of the latter are soluble in weak saline 
solutions. Some are insoluble, others soluble in concentrated saline 
solutions. It is on these varying solubilities that proteids are classified. 

All proteids are soluble with the aid of heat in concentrated mineral 
acids, in glacial acetic acid, and in caustic alkalis. Such treatment, how- 


1 Arch. f. d. ges. Physiol., Bonn, 1882, Bd. xxix. S. 400. 

* Centralbl. f. agric. Chem., Leipzig, 1882, p. 830. 

3 Chem. News, London, vol. xlviii. p. 179. 

4 Brit. Med. Jowrn., London, 1886, vol. i. p. 629 ; Lancet, London, 1888, vol. ii. p. 751. 


40 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


ever, decomposes as well as dissolves the proteid. Proteids are also soluble 
in gastric and pancreatic juices, but here again they undergo a change, 
being converted into the hydrated varieties of proteid known as proteoses 
and peptones. Solutions of the proteids are precipitated by a large 
number of reagents, but the proteoses and peptones furnish many ex- 
ceptions to this statement. 

The principal precipitants of proteids are :— 

1. Strong mineral acids, especially nitric, metaphosphoric, and 
phosphotungstic acids. 

2. Acetic acid with potassium ferrocyanide. 

}. Acetic or oxalic acid, with excess of certain neutral salts, such 
as sodium sulphate, sodium chloride, or magnesium sulphate. 

4. Salts of the heavy metals; basic lead acetate, mercuric chloride, 
silver nitrate, copper sulphate, ferric chloride or acetate, potassio- 
mercuric iodide, sodium tungstate, etc. The precipitates consist of 
the proteid in combination with variable amounts of the metal, in 
the form of albuminates. On the removal of the metal by a stream 
of sulphuretted hydrogen, the proteid is recoverable in an unchanged 
form. 

5. Tannin; or tannin and sodium chloride together. 

6. Saturation with ammonium sulphate or sodiomagnesium sulphate, 
or potassium acetate or carbonate. These precipitates are soluble on 
ern the solution of salt in which they are suspended. 

Picric acid. 

8. Salicylsulphonie acid. 

9. Trichloracetic acid. 

10. Alcohol, except in the presence of free alkali, when the proteids 
are slightly soluble in hot alcohol. 

The precipitate given by the proteoses is in many cases (as with 
nitric, trichloracetic, and salicylsulphonic acid, or with acetic acid and 
potassium ferrocyanide) soluble on heating, but re-appears when the 
solution cools. The greater number of the reagents mentioned do 
not precipitate peptone. It is precipitated completely by alcohol, 
tannin, and potassio-mercuric iodide, and incompletely by phospho- 
tungstic and phosphomolybdie acids. 

The following are the methods used to remove all proteid from a 
solution :— 


1. Briicke’s method} consists in the alternate addition of hydrochloric acid 
and potassio-mercuric iodide. 

Girgensohn’s method * consists in the addition of sodium chloride and 
tannin. 

3. Devoto’s method.»—This consists in boiling an acidulated solution 
of the proteid with excess of ammonium sulphate crystals; all proteids are 
precipitated by this means except peptone. Proteoses, if present, are 
precipitated but not coagulated, and can be extracted from the precipitate 
by water. 

4. By trichloracetic acid.—This method consists in adding to the solution an 
equal volume of a 10 per cent. solution of trichloracetic acid, boiling and filtering 
hot. The filtrate contains the proteoses and peptone, if these are present, and 
the precipitate contains the other proteids. This is by far the most rapid and 


1 Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1871. 
2 N. Repert. f. Pharm., Miinchen, Bd. xxii. S. 557. 
3 Ztschr. f. physiol. Chem., Strassburg, Bd. xv. 


GENERAL PROPERTIES AND REACTIONS OF PROTEIDS. 41 


simple method of separating the two classes of proteids.! If boiling is omitted, 
the proteoses are in part precipitated also (C. J. Martin). 

5. The alcohol method.—The solution is rendered faintly acid with acetic acid, 
and several times its volume of absolute alcohol are added. After twenty-four 
hours it is boiled and filtered ; the filtrate is proteid-free.?_ The action of alcohol 
on proteids is peculiar ; it precipitates proteids in the cold ; and the precipitate, 
if washed free from alcohol, is found to be readily soluble in suitable reagents 
such as saline solution. But if the precipitate is left in contact with the alcohol 
for days or weeks, the solubility of the precipitate is lost ; the precipitate has 
been converted into a coagulum. This loss of solubility, however, does not 
occur with proteoses and peptone, and thus this is another very good though 
tedious method of separating native proteids from products of proteolysis.® 

6. Salicylsulphonic-acid method.—This is recommended by Mc William.* 
The reagent precipitates albumins and globulins ; on heating, the precipitate is 
coagulated. The same reagent precipitates proteoses ; on heating, the precipitate 
dissolves, and re-appears on cooling. The reagent does not precipitate 
peptones. 

7. By boiling.—In some cases the proteids are precipitated or more properly 
coagulated by boiling after faintly acidulating the solution. This is the case 
with the albumins and globulins, and with the proteids which are usually 
found in morbid urines. For the separation of native proteids from proteoses 
and peptones, the method is not to be recommended, because boiling with even 
dilute acids leads to the formation of small quantities of these products of 
proteolysis. The use of this method has thus produced many mistakes ; it led 
Struve, Schmidt-Miilheim, and others, to the conclusion that a peptone-like 
substance exists in milk and in blood ; and more recently Chabrié,® by the use of 
the same method, has described a new proteose-like constituent of blood 
serum, to which he has given the name “albumone.” Chabrié’s mistake has 
been amply demonstrated by R. Brunner.® It should be added that Devoto’s 
method is not wholly free from the same objection.” 


For quantitative purposes the precipitate produced by these several 
methods may be collected, washed, dried, and weighed, then incinerated, 
and the ash deducted. Other methods that have been devised are 
densimetric methods, in which, after removal of the proteid, the loss of 
specific gravity is multiplied by a constant factor,’ and methods in which, 
by Kjeldahl’s process, a nitrogen estimation is made in the precipitate 
produced by some precipitant. Sebelien® recommends tannin for this 
purpose. 

Precipitation by neutral salts (German, Aussalzung).—There are a 
number of organic substances which can be precipitated from their 


1Obermayer, Med. Jahrb., Wien, 1888, S. 375-381; Starling, Journ. Physiol., 
Cambridge and London, vol. xiv. p. 131; C. J. Martin, ibid., vol. xv. p. 375 ; Halliburton 
and Brodie, ibid., vol. xvii. p. 169 ; Halliburton and Colls, Journ. Path. and Bacteriol., 
Edin. and London, 1895, vol. iii. p. 295. 

* Hoppe-Seyler, ‘‘ Handbuch,” S. 312; Schmidt, Arch. f. d. ges. Physiol., Bonn, Bd. 
xi. S. 10; Hoffman, Virchow’s Archiv, 1879, November, S. 255. 

3S. Martin, Goulstonian Lectures, Brit. Med. Journ., London, 1892, vol. i.; Gourlay, 
Journ. Physiol., Cambridge and London, 1894, vol. xvi. p. 32. 

4 Brit. Med. Journ., London, 1891, vol. i. p. 837; 1892, i. p. 115. The reaction was 
previously described by Roch, Pharm. Centr.-Bil., Leipzig, 1889, S. 549. 

> Compt. rend. Acad. d. sc., Paris, tome exiii. p. 557. 

§ Inaug. Diss., Bern, 1894. 
7M. Matthes, Berl. klin. Wehnschr., Bd. xxxi. S. 351; Halliburton and Colls, 
oc. cit. 

® Bornhardt, Ztschr. f. anal. Chem., Wiesbaden, 1870, S. 149; 1877, S.124; Huppert 
and Zahor, Zischr. f. physiol. Chem., Strassburg, Bd. xii. S. 467, 484. 

8 Jbid., Bd. xiii. S. 135 ; Konig and Kisch, Ztschr. f. anal. Chem., Wiesbaden, Bd. 
xxvil. S. 191. 


42 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


aqueous solutions, by the addition of certain neutral salts in large 
quantities ; in some cases complete saturation is necessary. In some in- 
stances, as in the precipitation of urates by ammonium chloride,’ or 
ammonium sulphate, the formation of an insoluble compound with the 
base of the salt used will explain the phenomenon. In other cases, 
especially in the case of colloidal substances, the water-attracting power 
of the salt is more probably the explanation.? The solutions used 
should not be too concentrated, or the thick precipitate obtained is 
difficult of filtration. 

The phenomenon is not confined to substances of a colloidal nature ; 
thus, picric acid is precipitable by this means; so are soaps, especially 
potassium soaps by sodium chloride. But it is in connection with non- 
diffusible substances,* and especially with proteids, that the method is 
most used. 

Proteids differ from one another a good deal in the readiness by 
which they are precipitated in this way. Ammonium sulphate added to 
saturation, precipitates all proteids except peptones® and certain forms 
of deuteroalbumose.® Half saturation with the same salt is sufficient to 
precipitate globulins,’ acid and alkali albumun and casemogen. Speaking 
generally, the globulins and nucleo-proteids are more readily precipitable 
by neutral salts than the albumins. Thus, globulins are precipitated by 
magnesium sulphate and sodium chloride, whereas albumuns are not, and 
some globulins, like fibrinogen, are precipitated by half-saturation with 
sodium chloride. If the operations are carried out at the temperature 
of the air, the precipitated proteids are not coagulated, but are 
soluble in suitable liquids; and they then again show their characteristic 
properties.® 

Heat coagulation —The albumins, globulins, and some nucleo-proteids 
are coagulated at different temperatures, by heating their solutions. 
The temperature varies with the reaction of the solution,® the quantity 
and nature of the salts present? (minute quantities of calcium salts 
favour heat coagulation as they do ferment coagulation)“ and 
under certain circumstances, especially in an alkaline solution, with its 
concentration.” 


1F. G. Hopkins, Journ. Path. and Bacleriol., Edinburgh and London, 1893, vol. i. p. 
451. 

2 A. Edmunds, Journ. Physiol., Cambridge and London, 1894-5, vol. xvii. p. 451. 

30. Nasse, Arch. f. d. ges. Physiol., Bonn, Bd. xli. 8. 504; F. Hofmeister and S. 
Lewith, Arch. f. exper. Path. u. Pharmakol., Leipzig, 1888, Bd. xx. S. 247; xxv. 
S21; 

+ On the precipitation of colloid carbohydrates by salts, see Pohl, Zéschr. f. physiol. 
Chem., Strassburg, Bd. xiv. 8. 151; R. A. Young, ‘‘ Proc. Physiol. Soc.,” 1896-97, p. xvi. in 
Journ. Physiol., Cambridge and London, 1897, vol. xxi. 

° Wenz, Zischr. f. Biol., Miimchen, Bd. xxii. S. 1. 

6 Kithne, ibid., Bd. xxiv. S. 1 and 308; Chittenden, Journ. Physiol., Cambridge and 
London, vol. xvii. p. 48. 

* Kander, Arch. f. exper. Path. u. Pharmakol., Leipzig, Bd. xx. 8. 411. 

8 On the precipitation of proteids by numerous salts, see Denis, ‘‘ Mémoire sur le 
sang,” p. 39; Schiifer, Journ. Physiol., Cambridge and London, vol. iii. p. 181; 
Halliburton, ibid., vol. v. p. 177; vii. p. 321; Hammarsten, Arch. f. d. ges. Physiol., 
Bonn, 1878, Bd. xvii. S. 424. 

® Traces of acid lower, of alkali raise, the temperature of coagulation ; more than 
traces convert the proteid into acid or alkali-albumin respectively, and these substances do 
not coagulate by heat.—Halliburton, Journ. Physiol., Cambridge and London, vol. 
y. p. 165. 

 Limbourg, Zschr. f. physiol. Chem., Strassburg, Bd. xiii. S. 450. 

1 Ringer and Sainsbury, Journ. Physiol., Cambridge and London, 1891, vol. xii. p. 170. 

2 Haycraft, Brit. Med. Jowrn., London, 1890, vol. i. p. 167. 


GENERAL PROPERTIES AND REACTIONS OF PROTEIDS. 43 


The temperature of heat coagulation of some of the principal proteids 
may be approximately stated as follows :— 


_ALBUMINS. GLOBULINS. 

Egg albumin 73° C. | Cell globulin . t 48°-50° C. 
Serum albumin (a) 73° ,, | Fibrinogen : 3 ; 5Brig, 
5 (2) 77° ,, | Serum globulin | 3 (ise) 

33 Gi) ear ; 84°, | Myosinogen . ; i 2) 
Muscle albumin f3%5 vihpeeklne *,. ; P ; (ayer 
Lact-albumin 77°,, | Crystallin : ’ , 133.35 
| Hemocyanin . ‘ : GSc.s 


With regard to the separation of proteids by the use of the method 
of fractional heat-coagulation, the opinion has been expressed by Haycraft 
that the results obtained are not trustworthy. It is probable, nevertheless, 
that the method is trustworthy, since the proteids so separated can be shown 
to possess other differences.! 


Mechanical precipitation of proteids—By mechanical means, such as 
shaking with sand, or even pouring from one test tube to another, a solution 
of exe-white deposits threads of insoluble proteid, reminding one of fibrin 
filaments, which also they resemble in their difficulty of solubility. BY 
prolonged shaking, 96 per cent. of the proteid present may be 
deposited. Other “proteids behave similarly, but as a rule less markedly, 
namely, egg globulin, vitellin, the proteids of blood plasma, myosinogen, 
potato proteid, plant vitellin, alkali albumin, and some specimens of 
caseimogen (Ramsden).? 

Indiffusibilit y.—The proteids belong to the class of substances called 
colloids by Thomas Graham; that is, ‘they pass with difficulty or not 
at all through animal membranes, or vegetable parchment, the substance 
usually employed in the construction of dialysers. Proteids may thus be 
separated trom diffusible (crystalloid) substances, like sugar and salts. 
If a mixture of albumin and globulin, dissolved in a saline medium as 
in blood serum, is placed in a dialyser, with distilled water outside, the 
salts and extractives pass through the membrane into the water, and 
water passes in; the proteids remain within; the albumin in solution, but 
the globulin, which is insoluble in water containing no salts, pr ecipitated. 

The term colloid does not necessarily imply that the indiffusible 
substances are not capable of crystallisation; for many of the pro- 
teids have now been crystallised; this is particularly the case with 
the vegetable proteids (p. 52), with hemoglobin (p. 61), with egg 
albumin, and with serum albumin. F. Hofmeister® was the first to 
crystallise egg albumin; a solution of egg white is mixed with an equal 
volume of saturated solution of ammonium sulphate, and the globulin so 


1 The following are the principal papers on this question :—Halliburton on ‘‘ Proteids 
of Serum,”’ Journ. Physiol. Cambridge and London, vol. v. p. 159; xi. 456; Corin and 
Berard, “Boe White,” Bull. Acad. roy. de méd. de Belg., Bruxelles, 1888, tome xv. p. 4: 
Colin and Ansiaux, ibid. 1891, tome xxi. p. 83; Haycraft ‘and Duggan, Brit. Med. Journ., 
London, 1890, vol. . p. 167 ; Proc. Roy. Soe. "Edin. 1889, p. 351; Centralbl. f. Physicl., 
Leipzig, Bd. iv. S. i : Fredericq, zbid., Bd. iii. S. 601. 3 Chittenden and Osborne on ““Corn- 
Proteids,” Am. Chem. Journ., Baltimore, vol. xiii. pp. 7 and 8; xiv. p. 1; Hewlett, 
Journ. Physiol., Cambridge and London, 1892, vol. xiii. p. 512; Ramsden, Proc. Physiol. 
Soc., London, 1892, p- 23 : A. di Frassineto, Sperimentale, Firenze, 1895, tome xlix. All 
the above except Hay craft and Ramsden defend the method. 

* Arch. f. Physiol., Leipzig, 1894, S. 517. 

STiscur: f. physiol. Chem.., Strassburg, Bd. xiv. S. 165; 1892, xvi. S. 187; see also 
Gabriel, cbid., 1891, Bd. xv. S. 456. 


44. CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


precipitated is filtered off. The filtrate is allowed to stand at the 
temperature of the air, and as it gets concentrated minute spheroidal 
globules of varying size, and finally minute needles, either aggregated or 
separate, make their appearance (Fig. 9). On examining these crystals, 
they are found to consist of egg albumin, with a variable (but usually 
small) admixture of ammonium sulphate. Serum albumin has similarly 
been obtained by Giirber and Michel in a crystalline form, from the 
blood serum of horses and rabbits. More recently still, caseinogen has 
been crystallised. When a solution of this substance is mixed with 


a Seek 


Fic 9.— Crystals of egg albumin. 


ammoniacal magnesia mixture, it proceeds after some days to deposit 
spheroliths, and ultimately aggregations of needle-like crystals. They 
contain 45 per cent. of ash, and 14°98 per cent. of nitrogen. Nuclein 
also yields a crystalline deposit with ammoniacal magnesia mixture 
(v. Moraczewski).? 

Byrom Bramwell and Noél Paton® have described a case of album- 


1 Sitzungsb. d. phys.-med. Gesellsch. zu Wiirzburg, 1894. Michel (ibid., No. 3, Bd. 
xxix.; Centralbl. f. d. med. Wissensch., Berlin, 1896, S. 152) gives full details of the method 
employed. The crystals are hexagonal prisms with the following percentage composi- 
tion :—C, 53'1; H. 7:1; N, 15:9; S, 1:9; O, 22:0; ash, only 0°22. They coagulate at 
51°-—53° C. («)p = — 61°. 

° Zischr. f. physiol. Chem., Strassburg, Bd. xxi. S. 71. 

3 Rep. Lab. Roy. Coll. Phys., Edinburgh, 1892, vol. iv. p. 47. 


——— 


GENERAL PROPERTIES AND REACTIONS OF PROTEIDS. 45 


inuria, in which the urine on standing deposited the proteid matter in a 
erystalline form (see Fig. 10). They considered it to be of the nature of 
a globulin. Huppert! has questioned this conclusion, and thinks it pro- 
bable that the proteid was heteroalbumose. 

It is not, therefore, upon the non-crystalline character of proteid, but 
upon the enormous size of the proteid molecules, whether crystalline 
or non-crystalline, that the difficulty of diffusion depends. It thus 
becomes interesting to inquire into the diffusibility of the proteids of 
lower molecular weight, namely, the proteoses and peptones. Peptones 
are diffusible; this has long been known; they are highly diffusible 
compared to albumin, but of low diffusibility as compared with salt, 


Fic. 10.—Proteid crystals from human urine.—After Byrom Bramwell and Noél Paton. 


The diffusibility of the proteoses has long been inferred, but it is only 
quite recently that it has been accurately made out that they are inter- 
mediate in this character between peptones and albumins. The work 
in this direction was done independently by Kiihne? and Chittenden,’ 
and both arrived at the same results. A curious fact found was, that 


_deuteroproteose (generally regarded as intermediate between the other 


proteoses and peptones) is less diffusible than protoproteose. But this 


1 Zischr. f. physiol. Chem., Strassburg, 1896, Bd. xxii. S. 500. 
* Ztschr. f. Biol., Miinchen, Bd. xxix. S. 1. 
° Journ. Physiol., Cambridge and London, vol. xiv. p. 483. 


46 CHEMICAL CONSTITUENTS OF BODY AND, FOOD, 


is quite in accordance with Sabanejeff’s? cryoscopic determination of the 
molecular weights of these substances; he gives the molecular weight 
of protoproteose as 2467 to 2640, of deuteroproteose as 5200, and of 
peptone as 400 or less. The diffusion power of the different sub- 
stances investigated by Kiihne was as follows:—Heteroproteose is 
the least diffusible of the proteoses; in neutral saline solutions it is 
precipitated as the salt passes out, and none goes through the dialyser ; 
dissolved in ammonia it loses 5°22 per cent. Deuteroproteose comes 
next (loss, 241 per cent.); then protoproteose (loss, 28°35 per cent.) ; 
while peptone loses 51 to 51°83 per cent. Hach experiment lasted 
_ twenty-four hours. 

Action on polarised light.—All the proteids are levorotatory. The 
specific rotatory power of some of the principal members of the group 
is as follows :— 


Proteids. Observer. Value of («)p. 

Serum albumin . : : 3 : : eee ae ey 

e : Hoppe-Seyler = 3b as5 
Egg albumin : : ‘ : . ; wae 4 at ee _ 39°-98 
Lact-albumin : : : F : . | Sebelien® — 36°-37° 
Serum glebulin . : ; : : ie eles —59°°75 
Fibrinogen . é : : 6 A ; Herrman ® — 43° 
Alkali albumin. j : ; ; : Haas — 62°°2 
Syntonin (prepared from myosin) . ‘ : Hoppe-Seyler —72° 
Casein (dissolved in MgSO, solution) . : Hoppe-Seyler — 80° 
Various proteoses . ; 5 : 5 . | Ktihne and Chittenden” | —70°-80° 


Colour reactions.—These are numerous, and doubtless depend for their 
occurrence on the various radicles which, as we have seen, are probably 
present in the proteid molecules. Many of them are given by certain of 
the decomposition products of the proteids; and by a careful comparison 
of these simpler substances, conclusions have been reached concerning the 
particular groups in the proteid molecule to which each reaction is due. 

The majority of the colour tests are due to the presence of the 
aromatic radicle; it will, therefore, be well to preface the description of 
the reactions themselves by a classification of the aromatic substances 
derived from proteids by putrefaction. Salkowski® arranges them into 
three groups; whether all these groups exist pre-formed in the proteid 
molecule, or are derived, as Maly considered, from only one aromatic 
group, matters but little in the question under investigation. The 
groups are as follows :— 

First group—The phenol group.—tThis includes tyrosine, the aromatic 
hydroxy acids, phenol, and cresol. 

Second group—The phenyl group—This includes phenylacetic and 
phenylpropionic acids. 

1 Ber. d. deutsch. chem. Gesellsch., Berlin, Bd, xxvi. 8. 385. _ 

2 Zischr. f. Chem., Leipzig, 1864, S. 737. 

3 Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, Bd. xi. S. 17. 

4 Arch. f. d. ges. Physiol., Bonn, Bd. xii. S. 378; Chem. Centr.-bl., Leipzig, 1876, 
295, 811, 824. 

5 Jahresb. i. d. Fortschr. d. Thier-Chem., Wiesbaden, Bd. xv. 8. 184. 

6 Ztschr. f. physiol. Chem., Strassburg, Bd. xi. S. 508, 

7 Zischr. f. Biol., Miinchen, Bd. xx, 8. 51. 

8 Ztschr. f. physiol. Chem., Strassburg, Bd, xii, S, 215, 


TR 


* 
i> 


GENERAL PROPERTIES AND REACTIONS OF PROTEIDS. 47 


Third group—The indol group, of which indol, skatol, and skatol- 
carbonic acid are the most important members. 

We can now proceed to the consideration of the proteid colour 
reactions. 

1. The xanthoproteic reaction.—This is characterised by the yellow 
colour given by boiling with nitric acid, turned orange by ammonia. 
O. Loew! considered that the yellow material was a mixture of oxynitro-, 
trinitro-, and hexanitro- albumin ; but these substances are ver y doubtful 
as chemical individuals. Salkowski found the reaction to be given by all 
the members of his first and third groups of aromatic substances. 
Pickering? found that salicylic acid, and salicylsulphonic acid, cholesterin, 
cholalie acid, and taurocholic acid also give the test. A large number 
of other organic substances which were tested did not give the same 
result. It was noticed that bodies with a benzene nucleus with one 
hydrogen replaced by hydroxyl, give the xanthoproteic reaction, whereas 
substances which contain a benzene nucleus without the hydroxyl, as 
phenylacetic and benzoic acids, do not. 

Millon’s reaction.—A. brick-red coloration occurs when proteid matter 
is boiled with Millon’s reagent (a mixture of the nitrates of mercury 
with excess of nitric acid); the reaction was thought by Kiihne® to 
be due to tyrosine. Salkowski also took this view, as the reaction is 
given by the substances in his first group, the most prominent member 
of which is tyrosme. Those in the second and third groups do not give 
the test. Nasse,* however, demonstrated that Millon’s reaction is due 
to benzene derivatives, in which one hydrogen atom has been replaced 
by hydroxyl (hydroxybenzene nucleus) and not to tyrosine. That 
Nasse’s view is correct is shown by the following considerations :— 
Kiibne and Chittenden® have found that certain anti-products of diges- 
tion, which yield neither leucine nor tyrosine on further digestion, or on 
decomposition with sulphuric acid, do not give the reaction. Schiitzen- 
berger © found that tyrosine is absent from the putrefaction products of 
gelatin. Now, Salkowski stated that gelatin does not react with Millon’s 
reagent. But Chittenden and Solley’ have found that the products of 
gelatin digestion give a characteristic reaction, and Pickering that pure 
gelatin and gelatinoses give it in a marked manner; thus confirming the 
statement made by Millon® in his original memoir. Gelatin, therefore, 
owes this property to something which is not tyrosine, but which, like 
tyrosine, contains a hydroxybenzene nucleus. 

Adamkiewicz reaction®—If glacial acetic acid in excess and then 
concentrated sulphuric acid are added to proteid, a violet colour with 
feeble fluorescence is produced. The test is by no means a certain one, 
and is given by proteoses and peptones in concentrated solutions only. 
It is not given by gelatin (Hammarsten). 

This test is only given by the aromatic substances of Salkowski’s 
third (indol) group. The strong reagents added are likely to produce 

1 Journ. f. prakt. Chem., Leipzig, N.F., Bd. iii. S. 180. 


2 Journ. Physiol., Cambridge and London, 1893, vol. xiv. p. 372. 

3 Zischr. f. d. ges. Naturw., Halle, Bd. xxix. S, 506 : Virchow’s Archiv, Bd. xxxix. 8. 180. 

4 Chem. Centr.-B1., Leipzig, 1879, Bd. x. 

> Ztschr. f. Biol., Miinchen, Bd. xxii, S. 423. 

6 Article in Wurtz’ “ Dict. de chim.,” 1886, Suppl. 1 A, p. 58. 

7 Journ. Physiol., Cambridge and Tae ‘vol. xii. p- 28. 

8 Compt. rend. Acad. d. se. , Paris, tome xxvill. p. 40. 

° Ber. d. deutsch. chem. Gesellsch. , Berlin, Bd. viii. S. 761, See also Wurster, Chem. 
Ztg., Cothen, Bd. xi. S. 187. 


48 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


considerable change in the proteid molecule; indol and skatol can 
hardly be considered to be simple cleavage products of the proteid 
molecule (see p. 29). 

Liebermann’s test! is performed by precipitating the proteid by 
alcohol, and then heating the washed precipitate with strong hydrochloric 
acid. The result is a violet-blue colour. The reaction is not given by pure 
peptone.” It is also not given by any of the aromatic putrefactive products 
of proteid, nor by a large number of other cleavage products of proteid 
which Pickering worked with. Its cause is therefore at present unknown. 

Krasser’s reaction.,—Alloxan in solution stains proteid matter a 
briliant red. It reacts in the same way with asparagin, aspartic acid, 
and tyrosine. The reaction is probably connected with the presence 
of amido groups. 

Piotrowski’s reaction.t—lf a few drops of dilute copper sulphate 
solution are added, and then excess of strong solution of caustic soda 
and potash, a violet solution is the result. If ammonia is used instead, 
a blue solution is formed. 

In the case of the proteoses and peptones, the result is a rose-red solu- 
tion with potash® and a reddish violet with ammonia. As the same colour 
is given by the decomposition product of urea called biuret,® the test 
is often called the biuret reaction (2CON,H, — NH,=C,0,N,H;). Biuret 
yields, on decomposition, compounds which contain cyanogen; for instance, 
by heat it is split into ammonia and cyanuric acid, (CN ),H, O; Biuret, 
cyanuric acid, xanthine, hypoxanthine, sarcosine, hydrocyanie acid, all give 
similar reactions to the proteids. Gnezda‘ considered it probable that the 
biuret reaction was due to a cyanogen radicle, and that the cyanogen in 
albumin and peptone is differently combined, corresponding to the sumilar 
differences in cyanuric and hydrocyanie acid respectively. Pickering,* 
however, concludes, that the radicle in question is not CN but CONH. 


The related metals, nickel (Gnezda) and cobalt (Pickering) give correspond- 
ing colour reactions, which may be summarised in the following table :-— 


Copper Sul- | Copper Sul- | Nickel Sul- | Nickel Sul- | Cobalt Sul-| Cobalt Sul- 
Proteid. phate and phate and phate and phate and phate and phate and 
Ammonia, Potash. Ammonia. Potash. Ammonia. Potash. 


Native proteids ) 
(albumin s, 


| : 6 
globulins, and }| Blue Violet Nil Yellow Nil ee ce 
nucleo-pro- | pune 
teids) J 

Products of ie 
(ES eta Violet Rose-red | Yellow Orange Nil | Red-brown 


teosesand ep | 
tones) 


Pickering found that when a cobalt salt has entered into the proteid 


1 Jahresb. ti. d. Fortschr. d. Thier-Chem., Wiesbaden, Bd. xvii. 8. 8 ; Chem. Centr.-B?., 
Leipzig, 1887, Nos. 18 and 25. 

* Le Nobel, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, Bd. xvii. S. 3. 

3 Monatsh. d. Chem., Wien, Bd. vii. S. 673. 

4 Sitzungsb. d. k. Akad. d. Wissensch., Wien, Bd. xxiv. S. 335. 

® Briicke, Monatsh. d. Chem., Wien, Bd. iv. 

6 Wiedemann, Ann. d. Phys. u. Chem., Leipzig, Bd. xxiv. S. 67. 

7 Proc. Roy. Soc. London, 1889, vol. selva: p-. 202. 

8 Journ. Physiol., Cambridge and London, 1893, vol. xiv. p. 347. 


CLASSIFICATION OF PROTEIDS. 49 


molecule, it can be easily displaced by a nickel salt, and then in turn by a 
copper salt, each yielding its characteristic colour reaction. He examined 
these and other reactions in connection with various albuminoids as well; the 
addition of cobalt sulphate and potash to gelatin he found to produce a play 
of colours in the order of those of the spectrum, commencing with violet. 

Drechsel! has drawn attention to an old observation of Krukenberg’s, that 
at the boiling temperature there is in the so-called biuret reaction a reduction 
of the cupric to cuprous oxide; the latter, however, remains in solution. 
Drechsel shows that the reduction also occurs at the ordinary temperature. 
C. J. Martin? is also of opinion that the biuret reaction is a reduction. 
He finds that alkali albumin dissolves cuprous oxide and forms a pink solution, 
never violet or purple ; these latter colours, when the.test is ordinarily performed 
with copper sulphate, are due to admixture with cupric hydrate, held in solu- 
tion by the proteid and not reduced. The most powerful reducing proteids are 
proteoses and peptone, hence the pink biuret reaction; whereas the native 
proteids have a smaller reducing power, and the pink colour is mixed with the 
blue cupric hydrate, and so the colour obtained is a violet. 


From the preceding study of the properties and reactions of the 
proteids, it will be gathered that since many other substances give the 
same tests, a proteid can only be identified by employing a large 
number of its reactions. Winternitz? recommends a combination of a 
precipitant and colour reactions. The precipitant he has chiefly used 
in cases of albuminuria is acetic acid and potassium ferrocyanide. The 
precipitate so obtained gives the colour reactions well. This is also the 
case with the precipitate produced by several other reagents, among 
which may be mentioned salicylsulphonic acid,* and the halogens.° 


CLASSIFICATION OF PROTEIDS. 


It will be seen from the preceding description of the proteids, that 
I have used the term proteids throughout as an equivalent for albuminous 
substances (German, Hiweisskérper); certain other substances (such as 
hemoglobin, mucin, nucleo-proteids) named proteids, by Hammarsten, 
Neumeister, and other continental writers, will be treated separately 
as compound proteids. 

The proteids may be divided into those of animal and those of 
vegetable origin. There does not appear to be any essential difference 
between these two classes, and each can be subdivided in the same 
manner into sub-groups, but the distinction is a convenient one in practice. 

Animal proteids.—Class 1. Albumins——These are proteids which 
are soluble in water, in dilute saline solutions, and in saturated solutions 
of sodium chloride and magnesium sulphate. They are, however, pre- 
cipitated by saturating their solutions with ammonium sulphate. Their 
solutions are coagulated by heat, usually at 70°-73° C. Serum albumin, 
egg albumin, lact-albumin are examples. 

Class 2. Globulins.—These are proteids which are insoluble in water, 
soluble in dilute saline solutions, and insoluble in saturated solutions of 
sodium chloride, magnesium sulphate, and in half-saturated solution of 


1 Ztschr. f. physiol. Chem., Strassburg, 1895, Bd. xxi. S. 68. 
2 Private communication to author. ‘ 
3 Ztschr. f. physiol. Chem., Strassburg, Bd. xy. 8. 187; xvi. S. 489. 
* Pickering, Joc. cit., p. 377. 
°F. G. Hopkins, Proc. Physiol. Soc., June 12, 1897. 
VOL. I.—4 


50 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


ammonium sulphate. Their solutions are coagulated by heat, the 
temperature of heat coagulation varying considerably. Fibrinogen, 
serum globulin, globin, paramyosinogen, and myosinogen, crystallin, 
vitellin,’ egg globulin are examples. 


The differences in solubility of these two important classes of native 
proteids may be stated in tabular form as follows :— 


Reagent. Albumin. | Globulin. 

Water. ! ; : ; : ‘ : Soluble Insoluble 
Dilute saline solution 2 % : : : a Soluble 
Saturated solution of magnesium sulphate or 

sodium chloride. : E é : : i Insoluble 
Half-saturated solution of ammonium sulphate 35 “5 
Saturated solution of ammonium sulphate - Insoluble - 

' 


Class 3. Albuminates—These are proteids derived from either 
albumins or globulins by the action of weak acids or alkalis. The term 
has been extended to include metallic compounds of the proteids, but 
restricting it here to acid albumin or syntonin, and alkali albumin, the 
class may be defined as consisting of proteids which are insoluble in 
water, and in neutral solutions containing no salt. They are soluble in 
acid or alkaline solutions, and in weak saline solutions. They are 
precipitated by neutralisation, and resemble globulins in their behaviour 
to neutral salts. Their solutions are not coagulated by heat. 

A less soluble variety of these proteids, called Lieberkiihn’s jelly, 
is formed by adding strong acid or alkali respectively to undiluted 
white of ege. 

Caseinogen, formerly regarded as a member of this group, will be 
studied with nucleo-proteids and with milk. 

After egg albumin is treated with formaldehyde it remains soluble 
in water, but is not coagulable on heating? 

Class 4. Products of proteolysis ; proteoses and peptones. —These will 
be studied in detail in connection with digestion. They can, however, 
be formed by other hydrolysing agencies than digestive juices, such as 
treatment with mineral acids, or superheated steam. The term proteose 
for the intermediate products of hydration is a convenient general name, 
which includes not only albumoses, but also vitelloses, globuloses, caseoses, 
myosinoses, and the like. 

Class 5. Coagulated proteids—This class includes the proteids in 
which coagulation has been produced by heat, and those in which coagu- 
lation has been induced by ferment action, such as fibrin, myosin, casein, 
and anti-albumid, an insoluble by-product formed in gastric digestion. 

Since the individual members of these groups have either been 
described in preceding sections, or will be discussed elsewhere under 
other heads, such as blood, milk, etc., they need not be further considered 
in this place. 

? Vitellin, unlike other globulins, is not precipitated by sodium chloride. Some regard 
it as a nucleo-proteid. It will be more fully discussed later. 

> Blum, Zéschr. f. physiol. Chem., Strassburg, 1896, Bd. xxii. S. 127; Berl. klin. 
Wehnschr., 1897, Bd. xxxiii. S. 1043. 

* On ‘‘ Atmid-albumoses ” (that is, those formed by superheated steam) see Neumeister, 


Ztschr. f. Biol., Mimchen, Bd. xxvi. S. 57; Chittenden and Meara, Journ. Physiol., 
Cambridge and London, 1894, vol. xy. p. 501. 


VEGETABLE PROTEIDS. 51 


Vegetable proteids.—The amount of proteid matter in plants, 
especially in those which are full grown, is less than in animals. It occurs 
dissolved in their juices, or in their protoplasm, or deposited in the form 
of granules called aleuron grains. Plant proteids have frequently been 
obtained in a crystalline form. They may be divided into the same 
classes as the animal proteids. 

Class 1. Albumins.—Small quantities of true albumin have been 
described by S. Martin! in the juice of the papaw fruit, and by Green? 
in the latex of several caoutchouc-yielding plants of the natural orders 
Apocyne and Sapotace. 

Class 2. Globulins.—These are by far the most abundant natural 
proteids present in plants. This view, which was taken by Hoppe- 
Seyler,? is contrary to that of Ritthausen,t who regarded vegetable 
proteids as consisting chiefly of legumin and allied substances.° 

Class 3. Albuminates—Acid and alkali albumin are formed readily 
from vegetable proteids, especially from plant myosin. Legumin or 
vegetable casein was used synonymously with vegetable proteid by some 
of the earlier investigators,® but it is now usually regarded as alkali 
albumin, formed artificially in the extraction of the globulins by alkah. 
The name conglutin was introduced by Ritthausen’ for the more 
glutinous product obtained from almonds and lupins. 

Class 4. Proteoses and peptones—Proteoses have been described in 
latex, in papaw juice, and flours of different kinds. True peptones are 
not found in the circulating juices of plants. Probably the circulating 
proteids in plant life are proteoses, hemialbumoses (Vines), though amido- 
acids (leucine, tyrosine, asparagine, adenine, etc.)® also occur. These 
substances are formed by proteolytic ferments during germination. The 
best known of these ferments, papain, has been investigated by Wurtz, 
Martin, and others. Such ferments, as well as malting ferments, which 
convert the insoluble starch of the seed into the soluble sugar, are probably 
almost ubiquitous.’ In carnivorous plants, another ferment is met with 
of a somewhat different character. 

Class 5. Coagulated proteids—Vegetable albumin and globulin, like 
those of animal origin, are converted at a high temperature into an 
insoluble heat coagulun. 


With regard to the value of vegetable proteids as food, it may be stated that 
as a rule they are not nearly so readily digested as animal proteids. Prausnitz '? 


i Journ. Piysiol., Cambridge and London, vol. vi. p. 336. 

* Proc. Roy. Soe. London, vol. xl. p. 28. 

3 “* Physiol. Chem.,” S. 75. 

4 Ztschr. f. Chem., Leipzig, Ser. 2, Bd. iv. S. 528,541; vi. 126; Journ. f. prakt. Chem., 
Leipzig, Bd. ciii. S. 65, 78, 193, 273. 

®° Ritthausen defends his view in Chem. Ceutr.-Bl., Leipzig, 1877, S. 567, 57 

6 Hinhof, Neue allg. Journ. d. Chem., v. A. Gehlen, 1805, Bd. vi. S. 126, 5 
and Cahours, Liebig, and others also examined this substance. 

” Tbid., Ser. 2, Bd. xxvi. S. 440. 

8 E. Schulze and E. Kisser, Landw. Versuchs Stat., Berlin, Bd. xxxvi. S. 1 ; E. Schulze, 
numerous papers in Ztschr. f. physiol. Chem., Strassburg. See especially Bd. xii. 8. 405. 

2 Gorup-Besanez, Ber. d. deutsch. chem. Gesellsch., Berlin, 1874, S. 1478; Krauch, 
Journ. Chem. Soc., London, 1878, Abst. p. 996; Green, Proc. Roy. Soc. London, vol. 
xli. p. 466; Thiselton Dyer’s Presidential Address, Sect. D, Brit. Assoc., 1888; Hansen, 
Bot. Ztg., 1886, S. 137 ; Ellenberger and Hofmeister, Centralbl. f. agric. Chem., Leipzig, 
1888, S. 319. The subject of enzymes and reserve materials in plants, however, is now 
a very large one, and it will be found discussed, with bibliography, in a series of articles by 
J. Reynolds Green, in Science Progress, London, vol. i. p. 342; ii. p. 109; iii. pp. 68, 376 ; 
v. p. 60. 

” Zitschr. f. Biol., Miinchen, Bd. xxiv. S. 227. 


52 CHEMICAL CONSTITUENTS OF BODY AND FOOP, 


experimented with beans; he found the feces contained as much as 30°3 of the 
nitrogen of the beans in an undigested condition. Beans thus compare 
unfavourably with lentils and bread, but even here there is a considerable 
undigested residue. The investigations of Rutgers! point to the fact that this 
is due rather to the admixture of vegetable proteids with cellulose and other 
indigestible materials than to any peculiarity in the proteids themselves. 

The foregoing brief account of the vegetable proteids may be amplified by 
further consideration of some of the points raised :— 


Researches on crystallised vegetable proteids.—In 1855, Hartig pointed out 
the existence of crystallised proteid matter in seeds. Four years later, Maschke® 
obtained hexagonal plates of proteid matter by extracting Brazil nuts with 
water at 40°-50° C., and evaporating the filtered extract at 40°. Nageli* de- 
signated such crystals as crystalloids. Weyl? identified the erystals as vitellin. 
Sachsse,® by Maschke’s method, and also by precipitating the aqueous extract 
by astream of carbonic anhydride, obtained several preparations of proteid from 
Brazil nut which he analysed. The precipitate consisted of small dises, 
not crystals. Schmiedeberg’ obtained crystalline products from the car- 
bonic anhydride precipitate by digesting it with magnesia solution at 35° C., and 
evaporating at the same temperature. Drechsel® obtained hexagonal crystals, 
by submitting the solution containing Schmiedeberg’s magnesia compound to 
dialysis against alcohol, and also by the slow evaporation of a warm sodium 
chloride solution of the proteid.? At Drechsel’s suggestion, Griibler !° applied 
this method with some modifications to the proteids of squash seed, from which 
he obtained octahedral crystals ; he obtained lime as well as magnesia crystalline 
compounds. Ritthausen,!! by similar methods, obtained octahedra and rhombic 
dodecahedra from expressed hemp cake, castor-oil seeds, and seeds of Sesamum 
mmdicum. Molisch™ has separated by the use of ammonium sulphate a 
crystalline proteid (phycocyanin) from the alga, Oscillaria leptotricha. 
Vines!’ found that the natural crystalloids, embedded in the ground 
substance of the aleuron grains, were hexagonal rhombohedra in some plants, 
and regular tetrahedra in others. 

Some of the details of Vines’ work are as follows :— 

The aleuron grains of the peony contain an albumose and vegetable 
myosin ; of the castor-oil plant, an albumose, a myosin, and vitellin ; of blue 
lupin, chiefly crystalloid vitellin. He classified aleuron grains into— 

1. Those soluble in water, albumose. 

2. Those soluble in 10 per cent. sodium chloride solution— 

(a) Without crystalloids, soluble in saturated sodium chloride solution, 
vitellin. 

(b) With crystalloids, insoluble in saturated sodium chloride solution, myosin. 

3. Those partially soluble in 10 per cent. sodium chloride solution. Some of 
these are crystalloid, some insoluble, some soluble in saturated salt solution. 

Vitellin is the principal constituent of egg yolk, and occurs there in the 
form of semicrystalline spherules, corresponding to the crystalloid aleuron 
grains of plants. The proteids described by Valenciennes and Fremy ' in the 


1 Ztschr, f. Biol., Miinchen, Bd. xxiv. S. 251. 2 Bot. Ztg., 1855, 8. 881. 
3 Journ. f. prakt. Chem., Leipzig, Bd. Ixxiv. S. 436. 
4 Bot. Mitth., Miinchen, 1863, Bd. i. 
° Arch. f. d. ges. Physiol., Bonn, Bd. xii. S. 635; Zéschr. f. physiol. Chem., Strassburg, 
Bd. i. S. 72. 
® “Die Farbstoffe, Kohlenhydrate und Proteinsubstanz,” Leipzig, 1877, S. 315. 
” Ztschr. f. physiol. Chem., Strassburg, Bd. i. S. 205. 
8 Journ. f. prakt. Chem., Leipzig, Bd. xix. S. 331. 
* See Griibler, zbid., Bd. xxiii. 8. 100. 10 Thid., Bd. xxiii. S. 97. 
1 [bid., Bd. xxiii. S. 481. 22 Bot. Zig., 1895, Bd. i. 8. 131. 
8 Proc. Roy. Soc. London, vol. xxviii. p. 218 ; xxx. p. 887 3 xxxi. p. 62. 
4 Ann. dechim., Paris, Sér. 8, tome 1. p. 129; Ann. d. Chem., Leipzig, Bd. exxvii. S. 188. 


VEGETABLE PROTEIDS. 53 


yolks of fishes’ eggs, and termed by them ichthin, ichthulin, and emydin, are 
regarded by Hoppe-Seyler as doubtful chemical units, and are probably mixtures 
of vitellin with nuclein and lecithin. Whether vitellin contains phosphorus in 
its molecule or not is a moot point. Some regard it as a nucleo-proteid rather 
than a globulin; others look upon the phosphorus generally found in it as 
belonging to either nuclein or lecithin, adherent to it as an impurity. The 
same question arises in connection with phytovitellin (vegetable vitellin). 
Recent analyses by Osborne! show that it contains no phosphorus, though 
Sachsse, one of the earlier workers, described the presence of this element. 

Proteids of flours.—Sidney Martin? found the principal proteids in wheat 
flour to be (1) a vegetable myosin, and (2) a soluble proteose, which he 
called phytalbumose. 

Gluten is a mixture of two substances— 

(a) Gluten fibrin, which is insoluble in alcohol, and formed from the 
myosin ; and 

(6) A proteose insoluble in water, formed from the phytalbumose. This 


Fic. 11.—Crystallised vitellin of the oat kernel.—After Osborne. 


insoluble proteose is, however, soluble in strong alcohol, and gives the sticky 
consistency to gluten; it corresponds to the two substances called gliadin and 
mucedin by Ritthausen.* 

- The existence of proteids soluble in strong, though probably not in abso- 
lute, alcohol, is a remarkable occurrence, and is not unique in vegetable 
physiology. 

Martin considered that gluten does not pre-exist in wheat-flour, but is 
formed on the addition of water by a ferment action.- This is supported by 
the fact that washing flour with water at a low temperature (2° C.) does not 
lead to the formation of gluten. The ferment, however, has not been 
separated, and Johannsen has advanced certain facts that tell against the 
ferment theory and in favour of the pre-existence of gluten in the flour. 


1 Am. Chem. Journ., Baltimore, vol. xiv. No. 8. 

2 Brit. Med. Journ., London, 1886, vol. ii. p. 104. 

3 Journ. f. prakt. Chem., Leipzig, Bd. Ixxiv. S. 193, 384. For other observations on 
gluten, see Bouchardat, Compt. rend. Acad. d. se., Paris, tome xiv. p. 962; Taddei, Gior. 
fisica di Brugnatelli, vol. xii. p. 860; Gunsberg, Journ. f. prakt. Chem., Leipzig, Bd, 
Ixxxv. S.-213. 

4 Ann. agronomiques, Paris, tome xiv. p. 420, 


54 CHEMICAL CONSTITUENTS OF BODY AND FOOD: 


Osborne! investigated the proteids of the cat and analysed three primary 
oat proteids, one soluble in alcohol, the second a globulin, and the third a 
proteid soluble in alkali only. From these, secondary proteids are obtained 
by mixing the ground oats with water; he regards the change as one pro- 
duced by ferment activity. 

In conjunction with Chittenden,? he worked out in a similar way the 
proteids of maize, and found there two globulins, one or more albumins, and a 
proteid soluble in alcohol. These differ in solubilities, coagulating points, and 
elementary composition ; one of the globulins is a vitellin, the other a myosin. 
A small amount of proteose also present was regarded as artificially produced 
in the processes of analysis. The proteid soluble in alcohol is called zein ; 
and it, like the globulins, is converted into an insoluble modification on ad- 
mixture of the flour with water. 

The proteids of flax seed* he found to be chiefly globulin, with smaller 
quantities of albumin, proteose, and peptone. 

In wheat Osborne and Voorhees+ describe five proteids :— 

1. Ghadin; a proteid soluble in alcohol, and like gelatin in some of its 
other properties. 

2. Glutenin ; a proteid soluble only in alkalis. 

3. Edestin ; a globulin of the vitellin class. 

4. Leucosin; an albumin, which Martin described as a myosin. 

5. Proteoses. 

They do not agree with Martin’s ferment theory of gluten formation. 
O’Brien °® has arrived at a similar conclusion; he regards gluten formation as 
due to hydration, though not produced by a ferment. The proteids in the 
flour he describes as globulins of the myosin and vitellin type, and a 
proteose which he regards as the mother substance of gluten. 

Other vegetable proteids investigated by Osborne are those of the kidney 
bean ® (two globulins called phaseolin and phaselin, and proteose); of the 
cotton seed (almost altogether proteose, with small amounts of edestin and 
insoluble proteid); of rye (gliadin, leucosin, edestin, and proteose); and of 
barley 7 (leucosin, proteose, edestin, and hordein, an insoluble proteid, 
corresponding to Ritthausen’s mucedin). He also investigated the chemical 
nature of diastase, and considers it is closely related to the albumin he has 
named leucosin. 

. Researches on proteolytic ferments in plants.—-Those in the papaw plant 
and in pine-apple juice are the best known, or most fully worked out. 

Papain was the name given by Wurtz to the proteolytic ferment in the 
juice of the papaw plant.. The close similarity of its action to that of 
trypsin was shown by 8. Martin.? The proteids in the juice are a globulin 
very like serum globulin, small quantities of an albumin, and proteoses of 
two kinds, with one of which the ferment appears to be closely associated 
(Martin).1¥ 

Bromelin.—This is the proteolytic ferment in pine-apple juice. Its 
existence was first noted by Marcano of Venezuela. It is made use of 
extensively in South America for the preparation of artificially digested 


1 Am. Chem. Journ., Baltimore, vol. xiv. No. 3. 

2 Ibid., vol. xii. Nos. 7, 8, and 9 ; vol. xiv. No. 1. 3 Tbid., vol. xiv. No. 8. 

4 Ibid., vol. xv. No. 6; ‘‘Seventeenth Ann. Rep. Connecticut Agric. Expt. Station,” 
Newhaven, 1893. 

> Ann. Botany, Oxford, 1895, vol. ix. pp. 171, 503. 

6 Journ. Am. Chem. Soc., N. Y., 1894, vol. xvi. p. 633. 

* [bid., 1895, vol. xvii. p. 5389. See also Oshorne and Campbell on proteids of potato 
on conglutin and vitellin, on legumin and other proteids of the pea and vetch, 7bid., 1896 
vol. xviii. No. 7. 

8 Compt. rend. Acad. d. sc., Paris, 1879, p. 425; 1880, p. 1379. 

® Journ. Physiol., Cambridge and London, vol. v. p. 213. 


a 


0 Tbid., vol. vi. p. 336, 


PROTEIDS AS POISONS. 55 


foods.!' Its action has been studied by Chittenden? and his pupils. It is a 
ferment of intense activity, and acts well in neutral, acid, and alkaline 
solutions, especially at 60° C. The ferment itself is associated or identical 
with a proteose-like substance in the juice. The products of its action 
(proteoses and peptone) are like those of other proteolytic ferments. 

I have alluded to these two ferments because they have formed the basis 
of very thorough investigations, not because they are in any way exceptional 
occurrences in the vegetable kingdom; as already stated, such ferments 
probably play an important part in all plants, by converting the insoluble 
proteid of the seed into the soluble nitrogenous substances of the sap.* 


PROTEIDS AS POISONS. 


The line between food and poison is easily crossed. When, a few 
years ago, the idea was first mooted that proteids may act as poisons, it 
was received with incredulity in many quarters; but there can now be 
no doubt that it is a fact. 

The best known of the vegetable proteid poisons are :— 

1. Those contained in the seeds of jequirity (Abrus precatorius). 
Warden and Waddell® named the poisonous substance abrin. S. Martin ® 
separated the two proteids—a globulin and a proteose—of which it is 
composed. The material is used as a drug to produce conjunctivitis. 

2. The proteid associated with or identical with papain (S. Martin). 

3. Licin, the poisonous proteid in castor-oil beans.’ 

4. Lupino-toxin from Lupinus luteus. 

The most important of the animal proteid poisons are— 

1. Snake poison. 

2. Proteids in the serum of certain fishes (conger eel, murzena, etc.).° 

3. Proteid poisons found in certain spiders,!’ and in the stinging 
apparatus of many insects. 

4. Ordinary peptones and proteoses; 0°35 gr. of commercial peptone 
per kilog. of body weight is in dogs usually fatal, when injected into 
the blood. ' 

5. Nucleo - proteids—These were called tissue  fibrinogens — by: 
Wooldridge, and cause intravascular clotting when injected into the 
blood (see “ Coagulation of Blood ”). 

6. Poisonous proteids produced by bacterial action. This subject 
has recently received much attention, and opens up the whole subject 
of toxins and antitoxins. To go into this matter thoroughly would 


1 Bull. Pharm., Detroit, 1891, vol. v. p. 77. 

2 Trans. Connect. Acad. Arts and Sce., New Haven, 1891, vol. viii. ; Journ. Physiol., Cam- 
bridge and London, vol. xv. p. 249. 

3 See further Green’s papers already quoted; also J. R. Green, ‘‘ On the presence of 
vegetable trypsin in the fruit of Cucumis utilis and other plants,” Ann. agronomiques, 
Paris, tome xix. p. 508 ; Neumeister, Zschr. f. Biol., Miinchen, Bd. xxx. Another recent 
paper on the subject (J. Hjort, Centralbl. 7. Physiol., Leipzig, 1896, Bd. x. S. 192) shows 
that there are similar ferments in fungi. 

+ Nencki’s opinion that poisonous proteids are more labile than other proteids can 
hardly be considered an explanation of this fact (‘‘ Ueber die labile Eiweissstoffe,” JV chnsehr. 
f. Pharm., 1891, No. 29). 

* “Non-Bacillar Nature of Abrus Poison,” Calcutta, 1884. 

6 Brit. Med. Journ., London, 1889, vol. ii. p. 184. 

7 Stillmark, Pharm. Centr.-Bl., Leipzig, 1890, Bd. xxx. S. 650. 

8 Schmidt's Jahrb., Leipzig, 1888, Bd. cciv. S. 10. 

9 Mosso, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, Bd. xviii. S. 92. 

 Kobert, Sitzungsb. d. Dorpater naturforsch. Gesellsch., 1888; Centralbl. f. d. med. 
Wissensch., Berlin, 1888, S. 544. 


56 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


lead us too far into pathological regions. The exact nature of the 
toxalbumoses and their antitoxins is by no means settled, but has 
already been followed by important practical results in the way of 
treatment. 

Snake poison.—The first group of proteid poisons in the foregoing 
list will furnish us with a typical example of the class, and it appears 
probable that, as the nature of the poison has been more thoroughly 
worked out in this than in most of the other cases, this will also form 
an important field of research in furnishing the key to the question of 
the nature of antitoxins; for protective imoculation has here been 
followed with considerable success (Calmette,’ Fraser ? ). 

The first investigation into the chemistry of snake poison of any 
importance was by Prince Lucien Buonaparte, on the poison of an adder, 
in 1843.2 He found that the activity of the poison was associated with 
the portion precipitable by alcohol; and he gave the name viperine to 
this precipitate. 

About 1860, Weir Mitchell * turned his attention to the subject, and 
he was the first to recognise that the toxic principle of the venom is 
albuminous in nature. He termed it crotalin in the ease of the rattle- 
snake. From that time till 1886 (in conjunction with Reichert) he 
continued his work, and confirmed his general conclusion in the case 
of the North American snakes. About 1871 the Indian snakes received 
their share of attention, and the names of Sir Joseph Fayrer® and 
Lauder Brunton ® are associated with valuable researches concerning 
the venom of the cobra, krait, and Indian viper. These*observers dealt, 
however, with the object mainly from the pomt of view of the physio- 
logical action of the venom. 

In 1883 Wall? in 1886 Wolfenden’ and in 1892 Kanthack,® 
published important contributions to our knowledge of cobra poison, 
the improved methods of chemical physiology enabling them not only 
to identify the poison as a proteid, but to show that the variety of 
proteid present is principally proteose. Two observers have described 
poisons other than proteid in snake venom, viz. Gautier, who regarded 

‘the venomous principle as alkaloidal; and Wynter Blyth, who gave the 
name cobric acid to a crystalline substance which he separated from 
cobra venom, and which he asserted to be highly poisonous. Recent 
work has failed to substantiate these results, and such alkaloids as are 
present (and they are generally absent) are non-poisonous ones. 

In their researches on the venom of the Australian black snake, C. 
J. Martin and M‘G. Smith” determined positively the nature of the 

1 ‘Te Venin des Serpents,” Paris, 1896. 

2 Brit. Med. Journ., London, 1895, vol. i. p. 1309. The name given to the antitoxin 
contained in the serum of immunised animals is antivenine. 

3 See Sir J. Fayrer, Proc. Med. Soc. London, 1884. 

4 N. Am. Med.-Chir. Rev., vol. v. p. 269 ; Med. News, Philadelphia, 1883 ; ‘‘ Researches 
upon the Venoms of Poisonous Serpents,” Smithsonian Contributions to Knowledge, 1886, 

5 Rep. on san. improvements in India, London, 1873, 1874. 

6 Rep. on san. measures in India, London, 1874; Proc. Roy. Soc. London, 1872-3, 
1873-4, 1875 and 1878; Sir J. Fayrer, ‘‘Thanatophidia of India,” London, 1872, and 


numerous papers by same author in Edin. Med. Journ., and Indian Med. G'az., Caleutta, 
between 1868 and 1874. 


7 «* Indian Snake Poisons, their Nature and Effects.” 

8 Journ. Physiol., Cambridge and London, vol. vii. pp. 827, 357, 365. 

*bid., VOl. sill. p: S12: 0 Bull. Acad. de méd., Paris, 1881. 

N Analyst, London, 1876, vol. i. 

2 Proc. Roy. Soc. New South Wales, Sydney, July 3, Aug. 3, 1892; Journ. Physiol., 
Cambridge and London, 1893, vol. xv. p. 380, 


a 


SNAKE POISON. 57 


venom. By appropriate experiments they excluded micro-organisms, 
ferments, ailtealoids, ptomaines, and crystalline acids.t They next showed 
that there are three proteids in the secretion; one, an albumin, is not 
irulent; but the other two, which are proteoses (proto- and hetero-pro- 
teose), are extremely poisonous. Their action is the same as that of the 
venom itself. They, like the venom, can be momentarily boiled without 
impairing their activity, but prolonged boiling for days destroys their 
virulence. 

The action of the poison is local and general. The most marked 
local effect is oedema; the general symptoms in non-lethal doses consist 
of twitching and conv ulsions. A fatal dose kills within a few seconds 
or minutes. There is also a peculiar effect on the blood. More than a 
century ago, the Abbé Fontana? noticed that the blood of animals 
killed by viper bite remained fluid. Brainard,* writing more than forty 
years ago, states that when death occurs immediately, in animals bitten by 
rattlesnakes, the blood is found at the post-mortem examination to be 
clotted; but if some time elapses before the animal succumbs, the blood 
remains fluid in the vessels. The continued fluidity of the blood has 
since then been noted by numerous observers in the case of various 
snakes. These observations are explained by C. J. Martin’s researches. 
He found that different doses produce different results. Immediately after 
the introduction of the venom, the coagulability of the blood increases, 
and this increase in the case of moderate or large doses (more than 
00001 grm. per kilog. of body weight) culminates in intravascular 
clottmg of greater or less extent. The injection of smaller doses 
produces a transient phase of increased coagulability, but after two 
minutes this is succeeded by a negative phase; the blood when drawn 
either fails to clot at all, or does so only after the lapse of several hours. 
The thrombosis occurs more readily in venous than arterial blood, and is 
frequently confined to the portal area. These results show a great 
resemblance between the action of the venom and that of nucleo-proteid. 
The effect of diminished coagulability is not unexpected, seeing that the 
principal substance in the venom is proteose, but the minuteness of the 
dose necessary is very striking and distinctive. The smallness of the dose 
suggests that the injected material does not itself contribute to fibrin- 
formation. It probably acts by producing disintegration of the cells of 
the endothelium of the blood vessels, or, according to Martin’s later 
observations, of the red corpuscles; in either ease the result would be 
liberation of nucleo-proteid material. 

With regard to the question of how these poisonous proteoses are 
formed, Martin puts forward the following hypothesis: the cells of 
the venom gland exercise a hydrolysing agency on the albumins supplied 
them by the blood, the results of which influence are the poisonous 
proteoses found in the venom. A difference between the process and 
digestion by pepsin, or by anthrax bacilli, is that the hydration stops 
short at the proteose stage, and is not continued so as to form peptone, 
or simpler nitrogenous materials, like leucine, tyrosine, or alkaloids. 
Gland epithelium is certainly capable of exercising such a hydrolysing 
influence; the conversion of glycogen into sugar in the liver cells is 
one of the best known examples. 


! A questionable trace of organic acid found did not possess toxic properties. 
2 Fontana, ‘‘ Poisons,” Trans. by J. Skinner, London, 1787. 
> Rep. Smithson. I nst., Washington, 1854. 


53 CHEMICAL CONSTITUENTS OF BODY AND FOG 


The following table, somewhat altered from Sidney Martin,! illustrates 


the analogy between various hydrolysing processes, proteid being in all cases 
the material acted on. 


PRopbUCTS. 


PRIMARY AGENTS. FERMENT. 


| 
i] 
| | Albuminous. 


Nitrogenous but not 
Albuminous. 
| a — 
1, Epithelial cell of gastric Pepsin. Proteoses, peptone. | Brieger’s _ pepto- 
gland toxin; a very 
doubtful basic 
| substance. 
2. Epithelial cell of pancreas | Trypsin. | Proteoses, peptone, | Leucine, tyrosine, 
lysine, arginine, 
: aspartic —_ acid, 
ammonia. 
3. Bacillus anthracis. .|None yet) Proteoses, peptone. | Leucine, tyrosine, 
found. | and an anthrax 
alkaloid. 
4. B. diphtherie . . .| Ferment not Proteoses. Organic acid of 
named, | doubtful nature. 
5. Epithelial cell of snake’s| None yet) Proteoses. Trace of organic 
venom-gland found. acid. 


Calmette? has worked out a table of the relative toxicity of venoms, as 
Roux and Vaillard have done for tetanus toxins, based on the ratio of 
lethal dose weight, subcutaneously injected, to body weight. He found the 
toxic value to be represented by the following numbers :— 


Cobra : : ‘ : ‘ : ‘ 3 4,000,000 
Hoplocephalus curtus ; ; : ‘ ‘ 3,450,000 
Pseudechis ; ; : : ; : . 800,000 
Pelias berus F : : : ; : : 250,000 
Martin places the toxic power of the two Australian venoms at— 
Hoplocephalus . : : : : ; . ° 4,000,000 
Pseudecis . : : : 2,000,000 


This is a very high virulence; put in another way, it means that 0°00025 
gr. of the one, and 0:0005 er. of the other poison is sufficient to kill a rabbit 
weighing a kilogramme. The virulence of snake poison much exceeds that of 
most of the poisonous proteids of zymotic diseases, though it is about the 
same as the diphtheria toxin of Roux and Yersin.* The following table also 
gives the toxic value of anthrax toxin,# and toxopeptone® from cholera 
cultures calculated in the same way :— 


Diphtheria toxin » ; : ; : : 4,000,000 (about) 
Anthrax albumoses : : : ; : 80 
Toxo-peptone é , , : : 3,000 


ANIMAL ALKALOIDS. 


Ptomaines and leucomaines.—The word ptomaine was. originally 
employed to designate those putrefactive products of animal substances which 
give the reactions of vegetable alkaloids, and which are more or less 
poisonous. The similar substances formed by metabolic activity, either 
from lecithin or proteids,® are called lewcomaines. 


1 Published in Brit. Med. Journ., London, March 1892. 

2 Ann. del’ Inst. Pastewr, Paris, 1894, tome vii. 

3 Quoted by Sims Woodhead, ‘‘ Bacteria and their Products,” p. 307. 

4 Sidney Martin, Rep. Med. Off. Local Gov. Bd., London, 1890-91. 

5 Petri, quoted by Vaughan and Novy, ‘‘ Ptomaines and Leucomaines,” p, 109. 

6 A discussion of the chemistry of the origin of alkaloids from proteids will be found 
in a paper by Latham, Lancet, London, 1888, vol. ii. p. 751. 


ii i a 


PTOMAINES AND LEUCOMAINES. 59 


The importance of the animal alkaloids was first brought into prominence 
in courts of law; the defence urged in certain notorious trials for murder, was 
that the alkaloid alleged to have been administered to the victim, or found in 
his stomach, really arose as the result of putrefactive changes occurring after 
death. It has, moreover, been demonstrated that alkaloids existing in 
different forms of putrefying food, produce poisonous symptoms. Sausages 
made with bad meat, certain fours of stale milk and cheese,! mussels and 
other shell fish,” at certain seasons of the year, produce serious symptoms 
in those who partake of them. 

It has further been supposed that, in many cases of disease, the poison 
formed by bacteria in the body, and which produces the symptoms of the 
disease, is of an alkaloidal nature. The probability that cholera is caused by 
an alkaloid was first pointed out by Lauder Brunton,* from the similarity of 
the symptoms to those produced by muscarine poisoning. Two alkaloids at 
least have, in fact, been discovered in cholera, and in cultures of Koch’s 
comma bacillus, and have been named cadaverine and putrescine, but they 
cannot be the actual poisons in cholera, because they are not markedly 
toxic. The same two alkaloids are found in the urine and feces in 
totally different pathological conditions, namely, cystinuria,t and pernicious 
anemia.” 

Alkaloids in animal tissues were first described by Dupré and Bence 
Jones ;° the substance they separated they called “animal quinoidine” ; 
about the same time, Marquardt’ obtained an alkaloid from a corpse, and 
named it “‘septicine.” Schmidt* and Panum’ obtained a substance they 
named sepsine from septic fluids, and they considered that it was the cause of 
septicemia. Later, prominent workers at the subject have been, Selmi,” 
Gautier, and Brieger;' to Brieger we owe the best methods of obtaining 
these substances in a state of purity. Brieger separated some alkaloids with 
such powerfully toxic properties, that he named them toxins; these include 
typhotoxine (from cases of typhoid fever), and tetanine™ (from cases of 
tetanus). 

All poisons produced by bacteria are, beworen not necessarily ptomaines. 
In fact, many of the toxins and antitoxins have been shown to owe their 
power, at one time ascribed to ptomaines, to the tox-albumoses or poisonous 
proteids (see “‘ Proteids as Poisons,” p. 55). 

A few details concerning the principal animal alkaloids may be added. 

Parvoline (C,H,.,N).—This was first separated from the putrid flesh of the 
mackerel and horse. It is an oily base, but its chloroaurate and chloro- 
platinate are crystalline (Gautier). 

Hydrocollidine (C,H,,N, boiling point 210° C.), and 

Collidine (C,H,,N) one been obtained from flesh, from putrid ox pancreas, 
and from gelatin. Nencki considers collidine to be isophenylethylamine, 


C, H. Be ol ‘, These three bases are all highly toxic. 


1 Vaughan separated an alkaloid, which he named tyrotoxicon, from certain forms of 
bad cheese, Zischr. f. physiol. Chem., Strassburg, Bd. x. S. 146. 

2 My tilotoxin is the alkaloid separated from mussels by Brieger. 

3 Rep. Brit. Ass. Adv. Sc., London, 1873. 

4 Baumann and Udranszky, Ztschr. f. physiol. Chem., Strassburg, Bad. xiii. S. 562. 

° Hunter, Lancet, London, 1888, vol. ii. p. 654. 

® Proc. Roy. Soc. London, vol. xv. p. 73; Ztschr. i Chem. 1866, S. 348. 

7 Schuchardt in Maschka’s ‘‘ Handb. f. ger. Med.,” Bd. ii. S. 60. 

8 Inaug. Diss., Dorpat, 1869. 

9 Virchow's Archiv, Bde. xxvii., xxviii., and xxix. 

10 Ber. d. deutsch. chem. Gesellsch.. Berlin, Bd. xi. 8. 808. 

11 Numerous papers ; see especially Bull. Soc. chim., Paris, tome xi. p. 6. 

12 Brieger, ‘‘ Die Ptomaine,” 1885, part i. ; 1885, part ii. ; 1886, part ii. 

z Brieger, Berl. klin, Wehnschr., 1888, No. Wie 14 Loe., cit. 


60 CHEMICAL CONSTITUENTS OF BODY AND FOOD: 


Neuridine (C,H,,N,) is a constant product of putrefaction of proteids. It 
is broken up by sodium hydrate into dimethylamine and trimethylamine 
(Brieger). Isomeric with this, though differing from it in the solubility of its 
salts, 1s saprine. 

Cadaverine, a third isomeride, belongs to the diamine group, and in consti- 
tution is pentamethylenediamine (Ladenberg).' 

Putrescine (C,H,,N,) is also a diamine, being tetramethylenediamine. It 
usually accompanies cadaverine, but as a rule makes its appearance later.” 

All the above are free from oxygen ; the remainder are oxygenated. 

Neurine (C,H,,NO) and choline (C,H,,NO,) are constant products of 
cadaveric putrefaction, and their constitution has been described on p. 21. 
They are toxic, and derive additional interest from their close relationship to 
muscarine (C; H,,NO,), the alkaloid of the poisonous mushroom, Agaricus 
muscarius.® Muscarine was discovered by Schmiedeberg and Koppe.* 
Schmiedeberg and Harnack ® obtained it also by oxidising choline with nitric 
acid. Brieger found it in putrid fish, and it occurs in several vegetables.® 

The natural alkaloid is probably not identical, but isomeric with that 
prepared by the oxidation of choline ;7 more recently an alkaloid, with all the 
properties of the muscarine of plants, has been prepared artificially from mono- 
chloracetal and trimethylamine.* The constitutional formula of muscarine 
is— 

(CH,), 
H 
N CH,—Co 
OH 


and it is the aldehyde of the non-toxic betaine (trimethylglycocine).® 
Choline, neurine, and muscarine are all toxic; and are antagonistic to 
atropine, so far as relates to their action on the heart and glandular system.!? 
Gadinine (C,H,,NO,) is a less toxic alkaloid, which is mixed with the 
muscarine obtained by Brieger from putrefying cod-fish. 
Mytilotoxine (C;H,,NO, 5) is the active agent in mussel poisoning. 
Typhotoxine (C- i iN O,) is obtained from cultures of the typhoid bacillus, 
and was regarded by Brieger as the chemical poison in typhoid fever. 


Tetanine (Crp Ele, N 0,) is, or was supposed to be, the toxin in cases of 
tetanus (Brieger). 


Gautier completes his list of animal alkaloids by including a number of 
substances of the urie acid group (adenine, guanine, xanthine, hypoxanthine, 
etc.), and of the creatinine group (creatinine itself, and certain sub- 
stances separated from muscle, which are termed xanthocreatinine, C;H,)N,0, 


1 Ber, d. deutsch. chem. Geselisch., Berlin, Bd. xix. S. 2585. 

> Brieger, Berl. klin. Wehnschr., 1887, No. 44; Boeklisch, Ber. d. deutsch. chem. 
Geselisch., Berlin, Bd. xx. S. 1441; Baumann and Udranszky, ibid. Bd. xxi. S. 29388 ; 
Ztschr. f. "physiol. Chem., Strassburg, Bd. xiii. S. 562; Brieger and Stadthagen, Virchow’s 
Archiv, Bd. exv. Heft 3. 

3’ The Agaricus muscarius also contains a considerable amount of a non-toxic alkaloid, 
amanitine, Neumeister, ‘‘ Physiol. Chem.,” Pd. i. S. 71. 4 ‘‘ Das Muscearin,” Leipzig, 1869. 

° Arch. f. exper. Path. vu. Pharmakol., Leipzig, 1876, Bd. vi. S. 101. 

6 Such as Beta vulgaris, and the seeds of vetches and cotton. E, Schulze, Zschr. f. 
physiol. Chem., Strassburg, 1891, Bd. xv. S. 140; and 1892, Bd. xvi. S. 205. 

7 Boehm, Arch. f. exper. Path. u. Pharmakol., Leipzig, 1885, Bd. xix. 8. 87. 

8 Berlinerblau, Ber. d. deutsch. chem. Glesellsch., Berlin, 1884, Bd. xvii. S. 1139. 

9 Found in Beta vulgaris; betaine has been also synthetically prepared from mono- 

chloracetic acid and trimethylamine :— 
a3 )s 
CH,Cl.COOH + N(CH,), +H,O=N H, COOH + HCl. 
OH 

1 The fall of blood pressure produced by choline and neurine is of cardiac origin 
(Mott and Halliburton, ‘‘ Proc, Physiol. Soc,,” Feb. 1897, p. xvill., in Journ. Physiol., 
Cambridge and London, vol. xxi.). 


: Rea: ——————— 


COMPOUND PROTEIDS. 61 


crusocreatinine, C.H,N,O, and amphicreatinine, C,H,,N-O,). These leuco- 
maines are regarded by Gautier, Bouchard, Pouchet, and others, as feebly toxic 
products of metabolism, from which the organism is normally freed by excretion, 
or by destructive oxidation; it has been suggested that their retention in 
the body may be the cause of certain obscure pathological conditions. The 
poisonous properties of normal urine are regarded by some as due to 
alkaloids of this nature, while others (Stadthagen) look upon the inorganic, 
especially the potassium, salts of urine, as the toxic agents,! 


COMPOUND PROTEIDS. 


The compound proteids are compounds of albuminous substances 
with other materials, which are as a rule also of a complex nature. 

They may be divided into the following groups :— 

1. Respiratory pigments. — The most important of these are 
hemoglobin and its compounds, chloroeruorin? (found in the blood 
of certain worms), and hemocyanin® (found in the blood of many 
molluscs and crustacea). Hemoglobin and chlorocruorin are compounds 
of proteids, with an iron-containing pigment. Hemocyanin contains 
copper in its molecule. TZwracin, the red pigment in the feathers of 
certain birds (plantain-eaters), also contains copper, and though not 
respiratory in function, should probably be included in the same group 
of substances. Hemoglobin with its derivatives and allies will be 
considered in a separate article. 

2. Gluco- proteids—Compounds of proteids with members of the 
carbohydrate group. This class includes mucins, mucoids, hyalogens 
and phospho-gluco-proteids. 

3. Nuclein—-Compounds of proteid with phosphoric acid, or with 
nucleic acid. 

4, Nucleo-proteids—Compounds of proteid with nuclein. 

5. Lecith-albumins.—Compounds of proteid with lecithin. 

We may consider the last four groups in detail. 

The gluco-proteids.—The gluco-proteids are mostly free from 
phosphorus (mucins, mucoids, and hyalogens), but some contain phos- 
phorus (phospho-gluco-proteids). 

Mucins.—The mucins are colloid, viscous substances of acid nature, 
soluble in alkalis, but precipitable from such solution by* acetic acid. 
On boiling with dilute mineral acid they yield a substance which 
reduces Fehling’s solution. They are found in the secretion of mucous 
glands, including the mucous salivary glands, and of slimy animals like 

1 For the principal papers on alkaloidal substances in urine, see Baumann and 
Udranszky, Zischr. f. physiol. Chem., Strassburg, Bd. xiii. S. 562 ; Stadthagen and Brieger, 
Virchow’s Archiv, Bd. exv.; Stadthagen, Zschr. f. klin. Med., Berlin, 1889, Bd. xv. Hefte 
5 and 6; Pouchet, Compt. rend. Acad. d. sc., Paris, tome xcviii. p. 1360 ; Bouchard, ibid., 
tome cii. pp. 669, 727, 1127 ; Griffiths, zbid., tomes exiii., exiv., and cxv. ; Gautier, Bull. 
Acad. de méd., Paris, 1886, tome xix. A very complete bibliography will be found in 
Huppert-Neubauer’s ‘‘ Analyse des Harns,” 9th edition, p. 241. 

* Quatrefages, see Gamgee, ‘‘ Physiological Chemistry,” vol. i. p. 131; Krukenberg, 
*‘Vergl. physiol. Studien,” 2te Reihe. Abth. 1, S. 87; Lankester, Journ. Anat. and 
Physiol., London, vol. ii. p. 114 ; vol. iii. p. 119.; MacMunn, Quart. Journ. Micr. Sc., 


London, Oct. 1885. 


3 Fredericq, Bull. Acad. roy. de méd. de Belg., Bruxelles, 1878, Sér. 2, tome xlvi. No. 
11; Halliburton, Journ. Physiol., Cambridge and London, vol. vi. p. 300. In the latter 
paper numerous references to other writers will be found. 

4 A. H. Church, Proc. Roy. Soc. London, 1869, vol. xvii. p. 486 ; Phil. Trans., London, 
1869, vol. clix. p. 627 ; 1892, vol. clxxxiii; p. 511; A. Gamgee, Proc. Roy. Soc. London, 
1896, vol. lix. p. 339. 


0 


62 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


snails! A mucinogen is found in the investment around frogs’ eggs; 
it is also the most “important constituent of the intercellular or nee 
substance of connective tissues, and has been especially investigated 
in the jelly-like connective tissues (vitreous humour, Whartonian 
jelly * ), and in tendon.® 


Elementary analysis of different mucins has given different results, as will 
be seen from the following table :— 


I 


Snalt Muciy. | TENDON MUCIN. | SUBMAXILLARY Mucirn. 

| | Hammarsten.6!  Loebisch.7 | Chittenden. | Hammarsten.9 Obolensky.10 
| Cm aye 50°32 48°3 48°26 i 48°84 52°31 

H . : 6°84 6-44 6°49 6°80 1°22 
| INF. : 13°65 | Te 7/53 tio 12°32 11°84 
| | 
| 8 DS Pel city (0 Shee tle hee 0°84 
| Orr* : 27°44 32°70 | 31°43 31°20 28°63 

| 


The mucins thus contain less carbon, and considerably less nitrogen, 
than proteids. ; 

Decomposition products of mucin.—By the action of superheated 
steam, a carbohydrate is split off from mucin, which was called anunal 
gum by Landwehr.'' He assigns to it the formula (C,H,,0;).. By 
the action of dilute mineral acids this is converted into a reducing but 
non-fermentable sugar or gummose (C;H,,0,). The gum-like substance 
obtained from submaxillar y mucin contains nitrogen. 2 The sugar 
obtained from tendon mucin by Chittenden yielded an osazone melting 
at 160°, and resembled that obtaimed from pentoses. F. Miiller?® has 
investigated the mucin of sputum. He found it yielded as much as 
25 to 52 per cent. of a reducing substance; this is not a pentose, but is 
probably glucosamine. 

1 Kichwald, Ann. d. Chem., Leipzig, Bd. exxxiv. 

* Giacosa, Zischr. f. physiol. Chem., Strassburg, Bd. vii. S. 40; Hammarsten, Arch. f. 
d. ges. Physiol., Bonn, Bd. xxxvi. ; Wolfenden, Journ. Physiol. , Cambridge and London, 
VOL. Vv. ‘p. 91. 

3R. A. Young, Journ. Plhysiol., Cambridge and London, 1894, vol. xvi. p. 325; C. Th. 
Morner, Ztschi. f. physiol. Chem., Strassburg, 1893, Bd. xviii. S. 245. References to previous 
literature will be found in these papers. Young arrived at the conclusion that the principal 
substance in vitreous humour is mucinogen, not mucin. 

4 Jernstroém, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1889, Bd. x. 8. 34. 
Young, Joc. cit., separated two mucins from the Whartonian jelly, one soluble, the other 
insoluble in excess of acetic acid. 

5 Rollett, Sitzungsb. d. k. Akad. d. Wissensch., Wien, Bd. xxxix. 8. 308, Stricker’s 
** Handbuch,” Bd. i. S. 72. Loebisch, Zschr. 7. physiol. Chem., Strassburg, Bd. x. 8. 40; 
Chittenden and Gies, Journ. Exper. Med., Baltimore, 1896, vol. i. p. 188. 


6 Arch. f. d. ges. Physiol., Boun, Bd. xxxvi. " Loc. cit. 
8 Loc. cit. The high percentage of sulphur found is attributed by Chittenden to proteid 
impurities. 


® Zischr. f. physiol. Cheim., Strassburg, Bd. xii. 

W Arch. f. d. ges. Physiol., Bonn, Bd. iv. S. 336. Probably Obolensky’s preparation 
was not so pure as Hammarsten’s. 

 Ztschr. f. physiol. Chem., Strassburg, 1881, Bd. viii. S. 124, 199; Arch. f. d. ges. 
Physiol., Bonn, Bde. xxxix. and xl. 

12 Hammarsten, ‘‘ Physiol. Chem.,” 3rd German edition, p. 39. 

8 Centralbl. f. Physiol., Leipzig, 1896, Bd. x. S. 480; Sitzwngsb. d. Gesellsch. z. Beford. 
d. ges. Naturw. zu Marburg, 1896, No. 6. 


THE GLUCO-PROTEIDS. 63 


By the action of dilute mineral acids on mucin, this reducing sub- 
stance, whatever its exact nature is, is also obtained, together with syntonin 
and proteose-like materials, from the proteid part of the mucin molecule. 
Strong acids lead to the formation of leucine, tyrosine, and levulinie acid 
(Landwehr). Strong alkalis lead to the formation of similar produets ; 
but weak alkalis, like lime water, have no effect on tendon mucin, though 
they readily break up submaxillary mucin (Loebisch). There is a good 
deal of difference among the mucins in their solubilities in acid and 
alkaline solutions. Obolensky obtamed pyrocatechin by boiling sub- 
maxillary mucin with caustic soda; but I have not succeeded in getting 
it from connective tissue mucin.} 

The putrefactive products of mucin are similar to those obtained 
from proteids. 


Mucoids or mucinoids.—These are mucin-like substances, which differ 
from the true mucins either in being non-precipitable from alkaline solu- 
tions by acetic acid, or in being readily soluble in excess of acetic acid. The 
designation was originally given to this class by Hammarsten, and includes 
the following substances :— 

1. The mucin from vitreous humour. 

2. The mucin from cartilage—chondro-mucoid (see ‘ Cartilage ”). 

3. The mucin from cornea—cornea-micoid.” 

4. Pseudo-mucin ; the colloid-like substance often found in ovarian fluids, 
and previously known as paralbumin and metalbumin.° 

5. A similar mucoid, sometimes found in ascitic fluid. 

6. Ovomucoid, a mucoid found in white of egg. This was first studied 
by Neumeister, who called it pseudo-peptone, then by Salkowski,® and finally 
by C. T. Mérner,’ who identified it as a mucoid. 

7. Paramucin, a substance found sometimes in ovarian cysts, differing 
from pseudomucin in reducing Fehling’s solution without previous treatment 
with acids (K. Mitjukoff).* Leathes,? who has worked at this substance under 
Drechsel’s supervision, finds that the reducing substance yields no osazone ; 
that on decomposition it yields sulphuric acid, and thus resembles chondro- 
mucoid; and on treatment with hydrochloric acid it gives off carbonic anhydride. 
Its nature is still uncertain. 

Hyalogens.—The term hyalin was originally applied to the principal 
constituent of the wall of hydatid cysts.!° Krukenberg!! extended the 
name to allied substances obtainable from other animal structures. In the 
natural state these substances are insoluble, and are termed hyalogens ; by the 
action of alkalis or superheated water they are converted into the soluble 
hyalins. Neossidin is the hyalin obtained from neossin,! the chief con- 
stituent of the edible bird’s nest. Chondrosidin and chondrosin are the hyalin 
and hyalogen respectively obtained from the sponge, Chondrosia reniformis, 


1 See also Young, Joc. cit. 

2C. T. Morner, Ztschr. f. physiol. Chem., Strassburg, Bd. xviii. S. 213. 

3 Hammarsten, ‘* Lehrbuch d. physiol. Chem.,”’ 3rd German edition, S. 366. See also 
Hammarsten, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, Bd. xi. S. 11; Land- 
wehr, Zischr. f. physiol. Chem., Strassburg, Bd. vii. S. 118. 

+ Hammarsten, ibid., 1891, Bd. xv. S. 202. 

> Ztschr. f. Biol., Miinchen, Bd. xxvii. 8S. 309. 

6 Centralbl. f. d. med. Wissensch., Berlin, 1893, Nos. 31 and 43. 

” Ztschr. f. physiol. Chem., Strassburg, Bd. xviii. S. 525. 

8 Inaug. Diss., Berlin, 1895. 

* Communication to Physiological Society, London, Oct. 17, 1896 (not published), 

W Liicke, Virchow’s Archiv, Bd. xix. 8.189. 

U Zischr. f. Biol., Miinchen, Bd. xxii. S. 261. 

2 The word ‘‘neossin” is Mulder’s, Bull. des sc. phys. in Nederlande, 1838, 8. 172; 
Green, Journ. Physiol., Cambridge and London, vol. vi. p. 40, pointed out the resemblance 
of the nest substance to mucin. 


64 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


spirographidin and spirographin from the skeletal tissues of the worm Spiro- 
graphis. Krukenberg obtained a hyalogen also from the tubes of Onuphis 
tubicola, another from the membrane of Descemet and lens capsule (membranin, 
C. T. Morner),! and another from hyaline cartilage (now called chondroitin- 
sulphuric acid, see “ Cartilage”). These substances are all, like the mucins and 
mucoids, decomposed by acids with the formation of a reducing substance. 
They differ from the mucins in some of their solubilities, but it is doubtful 
whether they should be classed apart from the mucoids. 

Phospho-gluco-proteids.—These substances not only yield a _ reducing 
carbohydrate or carbohydrate-like body, like the mucins and mucoids, but on 
gastric digestion they leave a residue of pseudo-nuclein, a substance which, 
like nuclein, contains phosphorus. Pseudo-nuclein does not, however, yield 
bodies of the xanthine group, on further decomposition, as do true nucleins. 
Among these substances are the following :— 

(a) Ichthulin, a substance separated from the eggs of the carp by Walter,? 
and at first supposed to be identical with vitellin. 

(6) Helico-proteid, secreted by the glands of the snail (Helix pomatia), and 
separated by Hammarsten.* By the action of alkalis a levorotatory carbohydrate 
(animal sinistrin) is split off; a dextrorotatory reducing sugar is obtained by the 
use of dilute mineral acids. 

(c) The principal constituent of the cells of the pancreas is a complex 
nucleo-proteid which Hammarsten* considers to be identical with trypsin ; 
by boiling this, it is split into coagulated proteid and a phospho-gluco-proteid. 
The sugar which this substance gives, on treatment with dilute acids, is 
probably a pentose (see p. 3). 

Kossel and his pupils have also obtained reducing sugar-like substances 
from yeast nuclein. 

In concluding the subject of the gluco-proteids, it may again be mentioned 
that Pavy regards all the common proteids (casein excepted) as having a 
glucoside constitution (see p. 30). Whether this be so or not, the fact insisted 
upon by Pavy that a carbohydrate may be obtained by hydrolytic decompo- 


sition of proteids has been confirmed by other observers. Thus K. Moérner™ 


obtained from serum globulin a reducing substance on treatment with 
hydrochloric acid, which, like Pavy’s, is optically inactive; but failed to get 
such a substance from purified myosin, vitellin, crystallin, serum albumin, and 
egg albumin. He got it from fibrin, but considered that it was due to carbo- 
hydrate in entangled blood corpuscles.® I myself was at one time of opinion 
that Pavy’s results, which were principally obtained with egg-white, were due 
to the admixture of the pure albumin with a mucoid (ovomucoid, which 
exists to the extent of 10 per cent. in egg-white) ; but I learn from Dr. Pavy 
that his method of preparing coagulated egg-white would exclude any large 
admixture of this kind. Pavy’s work, moreover, has been recently confirmed 
by N. Krawkow.® He found egg-white difficult to obtain free from ovomucoid, 
but the purest products he obtained always yielded a reducing substance, 
which gave a crystalline osazone (melting at 183° to 185° C.; Pavy gives 
189° C.). This reducing substance he regards as a carbohydrate, though he 
does not commit himself as to its identity. He, however, never found pen- 
toses, nor did he find that the gastric digestion of egg albumin yielded any 
carbohydrate. The same carbohydrate was obtained from acid albumin, 
alkali albumin, albumose, peptone, fibrin, serum albumin, serum globulin, 
and lact-albumin. Casein, vitellin, gelatin, and nucleo-proteid from peas 
gave a negative result. Albumin from peas yielded an osazone rather 


1 Zischr. f. physiol. Chem., Strassburg, Bd. xviii. S. 213. 2 Ibid. Bd. xv. 
3 Arch. f. d. ges. Physiol., Bonn, Bd. xxxvi. 

4 Zischr. f. physiol. Chem., Strassburg, Bd. xix. S, 19. 

> Centralbl. f. Physiol., Leipzig, Bd. vii. S. 581. 

6 Arch. f. d. ges. Physiol., Bonn, 1896, Bd. lxv. 8. 281. 


j 
g 
a 
a 
1 
q 


THE NUCLEINS. 65 


different in its characters from the one just described. H. Weydemann! has 
also confirmed Pavy’s work; he considers that the material in the proteid 
that yields the reducing substance is identical with Landwehr’s animal gum. 

The nucleins.—Lauder Brunton? described the nuclei of the red 
corpuscles of birds as consisting of a mucin-like substance. Plosz,3 
however, found that, though the material in question resembled mucin 
in its solubility in alkalis, and precipitability by acids, it was not mucin, 
as it contains a high percentage of phosphorus. About the same time 
Miescher * separated a similar phosphorus-rich substance from the nuclei 
of pus corpuscles; the pus was subjected to gastric digestion, and the 
nuclein alone remained undissolved. Later, Miescher° prepared a similar 
substance from the spermatozoa of different animals, and from egg-yolk ; 
Hoppe-Seyler® Kossel,’ and Loew® from yeast, Plosz® from the liver, 
Jaksch ?? and Geoghegan" from brain, Lubavin ” from cows’ milk, and 
Worm-Miiller from ¢ ego-yolk., 

Tt was soon surmised that nuclein is not a single substance, because 
the different nucleins vary in their solubilities, and even in their compo- 
sition. Miescher’s nuclein from spermatozoa, for instance, contained no 
sulphur. Of recent years our knowledge of the nucleins has been con- 
siderably advanced by Kossel, Liebermann, and others. 

It has long been known that metaphosphoric acid is a precipitant 
of albumin. Liebermann! examined this precipitate and found that it 
gave many of the reactions of nuclein. He therefore came to the con- 
clusion that nuclein is simply a compound of albumin with phosphoric 
acid. Malfatti1® carried this idea still further, for he found that, by 
fractional precipitation with different amounts of phosphoric acid, he 
was able to obtain a chain of nucleins with different amounts of 
phosphorus in each, and with varying solubilities, corresponding closely 
with those obtainable from nuclei. 

Pohl” however, very soon showed that Liebermann’s precipitate 
differs from true nuclein (7c. the nuclein from nuclei) in the fact that 
substances of the xanthine group are not obtainable from it on 
decomposition, and Kossel !8 has contested Liebermann’s and Malfatti's 
views chiefly on the same grounds. 

Kossel divides the nucleins into two groups. The first is that of 
the true nucleins. These are obtainable from nuclei; they yield on 
decomposition the xanthine bases—hypoxanthine, adenine, and other sub- 
stances of the same group. The second class of nucleins may be called 
pseudo-nucleins, and include those obtainable from milk, egg-yolk, 


* Inaug. Diss., Marburg, 1896 ; Centralbl. f. Physiol., Leipzig, 1897, Bd. x. S. 749. 

2 Journ. Anat. and Physiol., London, 2nd series, vol. ili. p. 91. 

3 Hoppe-Seyler, ‘‘ Med. Chem. Untersuch., ” 1871, Heft 4, S. 460. 4 Tbid., S. 441. 

° Verhandl. d. naturf. Gesellsch. in Basel, 1874, Heft i. 

6 “ Med. Chem. Untersuch.,” Bd. iv. S. 500. 

7 Zischr. f. physiol. Chem., Strassburg, Bde, iii. and iy. 

® Arch. f. d. ges. Physiol., Bonn, 1880, Bd. xxii. 9 Thid., Bd. vii. 

0 Tbid., Bd. xiii. 1 Ztschr. f. physiol. Chem., Strassburg, Bd-vi. 

2 Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. x. S. 2237. 

13 Arch. f. d. ges. Physiol., Bonn, 1873, Bd. viii. S. 190. 

4 Zischr. f. physiol. Chem., Strassburg. Numerous papers from Bd, viii. to present time. 

Ber. d. deutsch. chem. Gesellsch. , Berlin, Bd. xxi. 8. 598. 

16 Ber. d. naturw.-med. Ver. in Innsbruck, 1891-92, Bd. xx.; Zschr. J. physiol. Chem., 
Strassburg, Bd. xvi. S. 69; xvii. S. 8. 

7 Ztschr. f. physiol. Chem. , Strassburg, Bd. xiii. S. 292. 

AB ain d. physiol. Gesellsch., Berlin, Oct. 21, 1892 (in Arch. f. Physiol., Leipzig, 
1892 


VOL. 1.—5 


66 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


and Liebermann’s artificial nuclein. Altmann! showed that the 
nitrogenous bases just alluded to originate from a complex organic acid, 
which he termed nueleic acid, and that the true nucleins differ from one 
another in the relative quantities of proteid and nucleic acid which they 
contain. Nucleic acid is free from sulphur, and is in fact identical with 
Miescher’s nuclein from spermatozoa. Miescher’s formula for this 
sulphur-free material was C,,H,N,P,0,, Kossel’s is C,,H,,N,P,0,,. 
More recent investigations by Miescher,? which were not published 
until quite recently (after his death), by Schmiedeberg, led him to adopt 
the formula O,,H;,N,,0,,(?.0,), for nucleic acid. He further considered 
that in the spermatozoa, this acid is united to protamine. An exami- 
nation of a preparation of nucleic acid, made from yeast by Altmann, 
showed that here the formula was C,,H;)N,,0.(P,0;), (see further 
under “Spermatozoa ”). Nucleic acid does not give the proteid reactions. 
The relative amount of nucleic acid in different nucleins can be roughly 
determined by micro-chemical reactions with aniline dyes, nucleic acid 
having a great affinity for basic dyes like methyl-green.$ 

Hoppe- -Seyler’s classification of nucleins is the ‘following : == 

1. Nucleis like those found in spermatozoa, which contain no proteid, 
but consist only of nucleic acid. 

2. The true nucleins, those found in cell nuclei. They yield proteid, 
xanthine or alloxuric bases (hypoxanthine, xanthine, guanine, adenine), 
and phosphoric acid. Those richest in nucleic acid oceur in the chro- 
matic fibres of the nucleus; poorer in nucleic acid are the nucleims which 
occur in the nucleoli (e.g. pyrenin), and which constitute the chief bulk 
of the substance called plastin by histologists; these are comparatively 
insoluble in alkalis. They form numerous links in a chain which passes 
insensibly into the group of the nucleo-proteids. 

The para-nuclems (or pseudo-nucleins); these are the nucleins 
obtaimable from nucleo-proteids (casemogen, vitellin, cell nucleo-proteids). 
They yield (like Liebermann’s artificial nuclein) no nitrogenous bases, 
but only proteid and phosphoric acid on boiling with water or dilute 
acid. The nucleo-proteids of cell protoplasm can only be provisionally 
included in this group; they contain so little nuclein, that even if 
xanthine bases were obtained from these (and the point does not seem 
to have been thoroughly investigated yet) the small yield might escape 
detection. The nucleo-proteid from muscle yields some of these bases 
(see “ Chemistry of Muscle ”). 


There are at least four nucleic acids. They are compounds of an acid with 
various bases, such as adenine, hypoxanthine, guanine, and xanthine. They 
differ in the amount and character of the bases, and in the acid with 
which these bases are combined. That from the thymus is called adenylic 
acid (from the fact that its chief base is adenine). This, when heated with 
sulphuric acid, yields a crystalline substance called thymin* (C,H,N,O,), 
cytosine, ammonia, levulinic acid, formic acid, and phosphoric acid. The 
yield of cytosine, a new crystalline base (C,,H.)N,,0,+5H,O) amounts to 
about 2 per cent. of the nucleic acid employed. The presence of levul- 
inic acid among the products of decomposition is significant, and shows 
that adenylic acid contains a carbohydrate group. This agrees with previous 

1 Arch. f. Physiol., Leipzig, 1889, S. 524. See also Kossel, ib2d., 1891. 

2 Arch. f. exper. Path. u. Pharmakol. , Leipzig, 1896, Bd. xxxvii. S. 100. 

3 For a criticism of these microchemical methods, see Heine, Ztschr. f. physiol. Chem., 


Strassburg, Bd. xxi. S. 494. 
4 Kossel and Neumann, Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. xxvi. 8, 2753. 


THE NUCLEO-PROTEIDS. 67 


researches of Kossel, who obtained a carbohydrate from the nucleic acid of 
yeast.! 

Kossel and Neumann? have further shown that adenylic acid yields also 
a new acid called thymic acid, precipitable as a barium salt (C,,H,,N.,P,0,,Ba). 
The acid is readily soluble in cold water, and differs from nucleic acid in not 
being precipitated by mineral acids.* 


Researches such as these show how complicated the subject is, and 
how much yet remains to be discovered, especially regarding the nuclei 
acids. The nuclein bases are comparatively simple, and the principal 
ones may be arranged in two groups :— 

Adenine has the formula C,H,N,; on heating it with sulphuric acid, 
NH is replaced by O, and hypoxanthine is formed :— 

CEN ,.NH-+ HO "G71. N.0 > NA, 
(adenine) (water) (hypoxanthine) (ammonia) 

Both substances contain a radicle, C,H,N,, which Kossel terms adeny ; 
adenine is its imide, hypoxanthine its oxide. The following equation 
shows a similar relationship between guanine and xanthine -— 

©.HN,O.N.H ft Bi creo ME, 
(guanine) (water) (xanthine) (ammonia) 

On comparing the formule of hypoxanthine and xanthine with uric 
acid (C,H,N,O,), we see their close relationship. Leaving aside other 
possible ways in which uric acid is undoubtedly formed in the organism, 
we have here a way in which uric acid may arise by oxidation 
from the nuclein bases, and thus ultimately from the nuclei of cells.* 
The name “alloxuric bases” for these substances was suggested by 
Kriiger and Wulff.® They are often spoken of as the “ xanthine bases.” 

The nucleo-proteids,—These are compounds of nuclein with pro- 
teids. The amount of proteid matter is large, and the substances in 
question give the reactions of proteids, and in their solubilities approach 
very nearly to the globulins. On gastric digestion the nuclein they con- 
tain is left as an insoluble residue, but on pancreatic digestion a good 
deal of the nuclein is dissolved, and presumably, when this occurs in the 
body, is absorbed.® 

Hammarsten divides the nucleo-proteids into two classes ; the first, to 
which he restricts that name, yields true nuclein on gastric digestion; 
the other class he calls nucleo-albumins; these yield pseudo-nuclein on 
gastric digestion, and include caseinogen and vitellin. In addition to 
these, there are the phospho-gluco-proteids, which have already been 
described (p. 64). 

Nucleo-proteids, using the term in the widest sense, are obtain- 


1 Kossel and Neumann, Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. xxvii. S. 2215. 

* Zischr. f. physiol. Chem., Strassburg, Bd. xxii. S. 74. 

* It was later obtained from spermatozoa nuclein (Kossel, ibid., p. 188). Milroy (ibid., 
1896, Bd. xxii. S. 307) states that the precipitate formed on adding nucleic acid to a solu- 
tion of albumin resembles true nuclein in its characters ; whereas the precipitate produced 
by thymic acid is somewhat similar to para-nuclein or pseudo-nuclein. 

4 This subject has been specially taken up by Horbaczewski (Sitzungsb. d. k. Akad. d. 
Wissensch., Wien, Bd. c.), who has pointed out the close relationship between uric acid 
formation and leucocytosis. Diet increases uric acid formation by leading to an increase 
of leucocytes, or possibly, as some recent investigators think, the increase is chiefly due 
to the nuclein in the food (Weintrand, Chem. Centr.-Bl., Leipzig, 1895, Bd. ii. S. 54, 
234, 310). See also Umber, Zschr. f. klin. Med., Berlin, 1896, Bd. xxix. S. 174; Camerer, 
Ztschr. f. Biol., Miinchen, 1896, Bd. xxxiii. S. 139. 

° Ztschr. f. physiol. Chem., Strassburg, 1894, Bd. xx. S. 176. 

§ Popoff, Zischr. f. physiol. Chem., Strassburg, Bd. xviii. S. 533; Gumlich, idid., 8. 508. 


68 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


able from the nuclei and protoplasm of cells. They appear to be the 
most abundant of the proteid materials obtainable from cells. Nucleo- 
histon is the name of one of these separated from the thymus by Kossel 
and Lilienfeld+ The latter gives its percentage composition as 
C, 48:46; H, 7; N, 16°86; P, 3-025; 8°07; 0, 23-95) ieee 
percentage of phosphorus given here has never been obtained by me, 
from the numerous nucleo-proteids I have prepared and examined from 
the thymus and other organs. Details of these will be given under the 
heads of the various organs in question. In my own analyses, the 
amount of phosphorus rarely has exceeded 1 per cent. 


Nucleo-histon appears to be identical with the tissue fibrinogen of 
Wooldridge, but this included a variable amount of lecithin. Other 
forms of the same substance have been called cytoglobin and preglobin by 
A. Schmidt.” Wooldridge prepared his tissue fibrinogens from cellular 
structures, such as thymus and testis. The gland is finely minced and 
extracted with water for twenty-four hours. Weak acetic acid is then added 
to the decanted extract, and after some hours the precipitated nucleo-proteid 
falls to the bottom of the vessel. This is the method used by Lilienfeld in 
the manufacture of nucleo-histon. Another method, which I have largely 
used, is to grind up the finely minced organ with about an equal volume of 
sodium chloride in a mortar. The resulting viscous mass (originally called 
hyaline substance by Rovida) is poured into excess of distilled water. The 
nucleo-proteid rises in strings to the surface of the water, where it may be 
skimmed off. 

Prepared by either method, the nucleo-proteid may be dissolved in 1 per 
cent. sodium carbonate solution. This solution injected intravascularly in 
small doses in dogs produces a hindering of the coagulation of the blood 
(Wooldridge’s negative phase). In larger doses it produces intravascular 
coagulation.® 

The lecithin found associated with Wooldridge’s tissue fibrinogens is 
variable in quantity, and does not appear to be organically united to them. 
After its removal the nucleo-proteids continue to exercise their most distinctive 
physiological characteristic, in producing intravascular clotting.? 


In connection with nucleins and nucleo-proteids, it should be men- 
tioned that many of them contain iron, and, according to Bunge, con- 
stitute in foods the normal supply of iron to the body; in this sense he 
has called them hematogens. The composition of hematogen from egg- 
yolk he gives in percentages, which may be compared with the com- 
position of nuclein from yeast, as follows :— 


Hematogen. Nuclein from Yeast. 

C 42°11 40°81 
H 6-08 5°38 
N 14°73 15°98 
O 31°05 31°26 
S 0°55 0°38 
iP , : : 5°19 6°19 
Fe é : . 0-29 et. 


1 Zischr. f. physiol. Chem., Strassburg, Bde. xviii. and xx. 

* “* Weitere Beitr. z. Blutlehre,”” Wiesbaden, 1895. 

* Details with reference to the influence of nucleo-proteids on blood coagulation are 
given in the article dealing with that subject. 

‘Halliburton and Brodie, Journ. Physiol., Cambridge and London, 1894, vol. 
Xvii, p. 135. 

° Ztschr. f. physiol. Chem., Strassburg, 1884, Bd. ix. S. 49. 


THE ALBUMINOIDS. 69 
If the iron is, as it appears to be, in organic union, the nucleins that 
contain it must be among the most complex of known organic compounds, 
consisting of seven elements. 
The exact method in which the iron is combined is however, like the 
constitution of nuclein, still unknown. 


Zaleski! has succeeded in separating from the liver one of these iron-con- 
taining nucleins, which he terms hepatin. The subject has been largely worked 
by microchemical methods for the detection of iron; and the terms “ firmly 
combined” and “loosely combined” iron are often used, according as the com- 
pounds which contain that element give the reactions with difficulty or ease. 
Macallum? finds that the chromatin of nuclei contains iron; he regards 
it as the mother substance of hemoglobin, both in embryological develop- 
ment and during nutrition in extra-uterine life. He finds similar hematogens 
in plants, as did also Bunge. 


Lecith - albumins.—Liebermann* has given the name lecith-albu- 
mins to certain compounds of lecithin and proteid which he obtained from 
the kidney, gastric mucous membrane, lungs, spleen, and liver. The 
lecithin is not removable from these compounds by simple extraction 
with alcohol and ether. These, however, can hardly be considered to 
be immediate constituents of the cells, as they are obtained after sub- 
jecting them to a very severe process, namely, artificial gastric digestion. 
They yield no phosphoric acid and no xanthine bases on decomposition. 
According to their discoverer, they play an important part (in virtue of 
the acidity which they possess in common with nuclein compounds) in 
the separation of the hydrochloric acid of the gastric juice, and in decom- 
posing the alkaline salts of the blood plasma, so as to yield the acid 
salts of the urine. Much more extended investigations are needed, 
however, before important functions like these can be safely attributed 
to them. 

We have already seen that vitellin is a proteid which by some is 
regarded as a globulin, by others as a nucleo-proteid. Hoppe-Seyler * was 
inclined to regard the phosphorus found in it as due to a combination 
with lecithin, whereas Hammarsten looks upon some forms of vitellin as 
phospho-gluco-proteids. No doubt, vitellin is a name which covers a 
number of different substances; the substance Hoppe-Seyler worked 
with contained as much as 25 per cent. of lecithin. In those cases 
where the phosphorus is present as a nuclein, the nuclein obtained by 
gastric digestion is of the pseudo-nuclein variety. 


THE ALBUMINOIDS. 


The albuminoids form a heterogeneous group of substances allied to 
the proteids, but differing from them by certain marked characteristics. 
As a rule, they are found in skeletal and epidermal structures, and 
usually they are remarkable for their resistance to reagents. They 


1 Zischr. f. physiol. Chem., Strassburg, Bd. x. S. 453; xiv. S. 274; Chem. Centr.-B1., 
Leipzig, 1888, S. 759. See also Quincke, Deutsches Arch. f. klin. Med., Leipzig, Bd. xxv. 
S. 567; xxvii. S. 202; xxxiii. S. 23; Peters, ibid., Bd. xxxii. S. 182. 

* Macallum’s most recent papers are in Journ. Physiol., Cambridge and London, 1894, 
vol. xvi. p. 268; Proc. Roy. Soc. London, 1895, vol. lvii. p. 261; 1. 277; Quart. Journ. 
Mier. Sc., London, 1896, vol. xxxviii. p. 175; Rep. Brit. Assoc. Adv. Sc., London, 1896. 

3 Arch. f. d. ges. Physiol., Bonn, Bde. 1. and liv. 
faa. ‘Med. chem, Untersuch.,” 1868; Zéschr. f. physiol. Chem., Strassburg, Bd, xiii. S, 


jo CHEMICAL CONSTITUENTS OF BODY AND FOGP: 


include keratin, elastin, collagen, gelatin, reticulin, amyloid substance, 
and a group of materials called skeletins. 

Collagen.—Collagen is the mother substance of gelatin. It is the 
material of which the white fibres of connective tissue are made, and is 
the principal constituent of which the organic substratum of bone is 
composed ; it is there called ossein. In cartilage the material called 
chondrigen is collagen mixed with the mucinoid materials of the earti- 
laginous matrix, Collagen has also been obtained from the flesh of 
cephalopods. 

By boiling with water, especially if it is faintly acidified, collagen is 
converted into gelatin ; and gelatin is reconverted into collagen by 
heating it to 130° C. Hence collagen is regarded as the anhydride of 
gelatin (Hofmeister) ;? the reaction may be represented by the equation— 

Cyo2Hy5:N 3, 0x9—H, O= Cro Hy sgN 31005 

(gelatin) (collagen) 
The above formule, however, cannot be regarded as more than provisional, 
for we are as ignorant of the molecular constitution of the albuminoids 
as of the proteids. Schiitzenberger attributes the formula C,,H,.,N2,0s9 
to gelatin, and regards the sulphur described by other investigators as 
due to admixture with proteid impurities. Hammarsten,? on the other 
hand, regards the sulphur, of which there is 0°6 per cent., as an integral 
part of collagen and gelatin. 

Collagen is insoluble in water, alcohol, salt solutions, and dilute acids, 
and alkalis. It swells with dilute acids. Its decomposition products 
are the same as those of gelatin. 

Gelatin. Gelatin is a colourless, amorphous, and translucent sub- 
stance; it swells but does not dissolve in cold water; it readily dissolves 
in hot water, and on cooling the solution, if its concentration is greater 
than 1 per cent., it sets into a jelly. It contains a considerable amount 
of ash, the removal of which lessens its power of gelatinising.* 

Gelatin is precipitated by saturating its solution with neutral salts, 
like magnesium sulphate and ammonium sulphate. This is also true for 
gelatin which has been altered by the action of hot water so as to be no 
longer or only partially gelatinisable. 

Gelatin is not precipitated by acetic acid, nor by acetic acid and ferro- 
cyanide of potassium, nor by most of the heavy metallic salts that precipi- 
tate proteids. It gives a violet colour with copper sulphate and caustic 
potash ; it gives Millon’s reaction, but only a faint xanthoproteic reaction. 

It is precipitated by mercuric chloride, and also, as in the process of 
tanning, by tannic acid. Gelatin is levorotatory.’ 

Derivatives of gelatin——The prolonged action (twenty-four hours) of 
boiling water, or the shorter action of water heated above the boiling 
point, destroys the gelatinising power of gelatin. Gelatin, in fact, under- 
goes hydrolysis, being converted into the so-called gelatin peptones. 
Similar substances are formed duri ing digestion. Hofmeister distinguished 

1 Hoppe-Seyler, ‘‘ Physiol. Chem.,” S. 97. 

 Ztschr. f. physiol. Chem, Strassburg, Bd. ii. S. 315. 

8 “Physiol. Chem.,” 3rd German edition, S. 46. Analyses of gelatin were made in addi- 
tion to those quoted above by Mulder, Ann. d. Chem., Leipzig, Bad. xlv. ; ; Fremy, Jahresb. 
d. Chem., 1854; and Paal, Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. XXV. S. 1208. 

+ Nasse and Kriiger, Jahres. ti. d. Fortschr. d. Thier-Chem., Wiesbaden, Bd. xix) 29: 

° Nasse, Arch. f. d. ges. Physiol., Bonn, Bd. xli. S. 504. 

6 Salkowski, Ztschr. f. physiol. Chem. 55 Strassburg, Bd. xii. S. 215 ; Berl. klin. Wehnschr., 


1885, No. 2. 
7 "Hoppe- Seyler gives («)p——130°at 30°C, Nasse and Kriiger give («)p= — 136° to — 167°5°, 


THE ALBUMINOIDS. 71 


two of these substances, which he named semiglutin and hemicollin. 
Chittenden and Solley! distinguish between proto- and deuterogelatose, 
and true gelatin-peptone. Paal? has obtained similar substances by the 
use of hydrochloric acid. By the use of Raoult’s method, he gives the 
molecular weight of gelatin as 878 to 960, and of gelatin-peptone as 352. 

Strong reagents like sulphuric acid, on putrefaction, decompose 
gelatin with the formation of glycocine,* leucine, various fatty acids, 
glutaminie acid, carbon dioxide and ammonia. The absence of tyrosine 
should be noted. Schiitzenberger,t who has worked with gelatin by the 
same methods as he used with ‘proteids, considers that gelatin, like 
proteid, is a compound of urea with certain amido-acids. 

The importance of gelatin as a proteid-sparing food, though it will 
not replace proteid entirely ina diet, will be considered under “ Nutrition.” 

Chondrin is the name given to the impure gelatin obtained from 
cartilage (which see). 

Hlastin.—Elastin is a material yielded by the yellow fibres of con- 
nective tissue. It offers great resistance to reagents, and may be pre- 
pared from the ligamentum nuchee by extracting the finely divided 
tissue successively With re agents in which it is insoluble, and in which 
adherent fatty, collagenous, and Btba matters dissolve (boiling water, 
1 per cent. potassium hydroxide, 5 per cent. hydrochloric acid, alcohol 
and ether). By this means a substance free from sulphur is obtained. 
Chittenden and Hart,> in some of their preparations, omitted the 
extraction with potash, and in these a small percentage of sulphur (0°3) 
was obtained ; this may be due to proteid impurities, or it may be loosely 
combined in the elastin molecule. Schwartz ® has also prepared a sulphur- 
containing elastin from the aorta. 


The following table shows the results of elementary analyses in _per- 
centages :— 


Miiller.7 | Tilanus.8 Horbaczewski.9 paittenden | Schwartz. 
©. ./| 55-09-55-7 | 549-5565 | 54-32 5404 | 58-05 
H 7-11-7°67 7:25-7:41 | 6-99 7 2ual el 7:03 
N. | 1571-16-52 | 1752-17-74 | 16-75 16-7 | 16°67 
0 20°7-21'15 | 19°5-20°33 21-94 21-69 | 21:97 
8 a | 03 | 0:38 


Derivatives of elastin.—Klastin is gradually and slowly dissolved by 


1 Journ. Phystol., Cambridge and London, vol. xii. p. 25. 

2 Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. xxv. 

3 On the preparation and estimation of glycocine from gelatin, see C. S. Fischer, Zéschr. 
Ff. physiol. Chem., Strassburg, Bd. xix. 8. 164; and Gonnermann, Arch. f. d. ges. 
Physiol., Bonn, Bd. lix. 8. 42. 

+ Compt. rend. Acad. d. sc., Paris, tome cii. p. 1296. See also Buchner and Curtius, 
Ber. d. deutsch. chem. Geselisch., Berlin, Bd. xix. S. 850. 

° Ztschr. f. Biol., Miinchen, Bd. xxv. 8. 368; Stud. Lab. Physiol. Chem., New Haven, 
vol. iii. p. 19. 

6 Zischr. f. physiol. Chem., Strassburg, Bd. xviii. 

" Zischr. f. rat. Med., Leipzig, Dritte Reihe, Bd. x. pt. 2. 

8 Gorup-Besanez, “ Physiol. Chem.,” Aufl. 3, s. ee 

® Ztschr. f. physiol. Chem., Strassburg, Bd. vi. S. 


72 CHEMICAL CONSTITUENTS OF BODY AND FOOD: 


pepsin or trypsin.! Horbaczewski named the two products of digestion he 
obtained, hemielastin and elastin-peptone. Chittenden and Hart, using 
Kiihne’s methods and nomenclature, have shown that hemielastin is 
protoelastose, and elastin-peptone is deuteroelastose. 

On more complete decomposition elastin yields products very like those 
obtained from proteids, except that glycocine is obtained, but no aspartic 
or glutamic acid, and very little tyrosine.? Lysatinine but no lysine was 
obtained.? By fusing with potash, indol, skatol, phenol, benzene, but no 
methylmercaptan, were yielded (Schwartz). 


feticulin.—The fibres of reticular tissue, though histologically not 
distinguishable from those of areolar tissue, were first stated to be 
chemically different from them by Mall.* He asserted that no gelatin 
was obtainable from them, a statement corrected by R. A. Young? 
and subsequently by Siegfried.6 Siegfried, however, confirmed Mall's 
idea that the fibres contained something special, and separated from 
them a material he called reticulin. Reticulin has the following per- 
centage composition :—C, 52°88; H, 6:97; N, 1563; S, 188; P, 034; 
ash, 2-27. By decomposition it yields sulphuretted hydrogen, ammonia, 
lysine, lysatinine, and amidovalerianic acid, but no tyrosine and no glu- 
taminic acid. It gives the proteid reactions with the exception of Millon’s. 

Siegfried prepared reticulin from the mucous membrane of the 
intestine by digestion with trypsin and alkali. The residue was washed 
and extracted with ether, again subjected to tryptic digestion, and 
extracted with alcohol and ether; the collagen was removed by hot water. 

If glutaminic acid is absent, as Siegfried states, from the decomposi- 
tion products of reticulin, and it is certainly very abundant in the 
decomposition products of collagen and gelatin, there is distinct evidence 
that reticulin is a new material. 

We are therefore confronted with the difficulty, that the fibres of 
reticular tissue are anatomically continuous with and histologically 
identical with the white fibres of connective tissue, and yet they con- 
tain chemically this new material. The answer to the problem is pro- 
bably that reticulin is not specially characteristic of reticular fibres, 
but 1s present in all white connective tissue fibres. 

Keratin.—Keratin is the horny material of which the horny layer of 
the epidermis, hair, wool, nails, hoofs, horns, feathers, ete., are composed. 

It is prepared by successively boiling the tissue with ether, alcohol, 
water, and dilute acid; the insoluble residue is keratin. A variety of 
keratin called neurokeratin is found in neuroglia, and has also been 
described in the medullary sheath of nerve fibres; though here no doubt 
some of the histological appearances described may be artificially pro- 
duced by reagents. It resembles keratin in its general properties, but 
is less easily soluble in boiling solutions of caustic potash.’ 


1 Kiihne and Ewald, ‘‘ Die Verdauung als histol. Methode,” Verhandl. d. naturh.-med. 
Ver. zu Heidelberg, 1877, N. F., Bd. i. S. 451; Etzinger, Zéschr. f. Biol., Miinchen, Bd. x. 
S. 84; Horbaczewski, Joc. cit. ; Morochewetz, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wies- 
baden, 1886, S. 271; Chittenden and Hart, Joc. cit. 

* Drechsel, Ladenburg’s ‘‘ Handworterbuch,” Bd. iii.; see also Horbaezewski, Monatsh. 
d. Chem., Wien, Bd. vi. 

3 See, however, Hedin’s recent work referred to on p. 33 of this article. 

4 Anat. Anz., Jena, 1888, Bd. iii. No. 14; Abhandl. d. math.-phys. Cl. d. k. stichs. 
Geselisch. d. Wissensch., 1887, Bd. xiv. No. 3; xvii. No. 14. 

° Journ. Physiol., Cambridge and London, vol. xiii. p. 332. 

6 «* Habilitationschrift,” Leipzig, 1892. 

7 Ewald and Kiihne, Verhandl. d. naturh.-med. Ver. zu Heidelberg, N.¥., Bd. i. 
Heft 5; Kiihne and Chittenden, Zschr. f. Biol., Miimchen, Bd. xxvi. S. 291. 


ier 


THE ALBUMINOIDS. 73 


The following are some elementary analyses that have been made of 
keratin from different sources :— 


TISSUE . 3 From Hair. Nail. | Neurokeratin. | Horn. | 

ANALYST : V. Laar.1 Mulder.? Kiihne.* Horbaczewski.4 | 

C - | 50°60 | 51°00 56°1-58°4 50°86 

Ft . : 6°36 6°94 | 7°2-8:°0 6°94 

N 17°14 17°51 11°5-14°3 | 

©) | 20°85 | 21°75 
A SP in 2°80 16-22 | Sc eimai 


The main feature in the above analyses is the high percentage of 
sulphur,? which is in part in loose combination, and can be removed by 
alkalis or even by boiling water. 

An albuminoid obtainable from tracheal cartilage by C. T. Morner,’ 
and further investigated by Hedenius,’ is included by Hammarsten ° 
among the keratins, or as a substance intermediate between keratin and 
coagulated proteid. It contains only 1 per cent. of sulphur. Keratin 
gives the proteid reactions. 

Derivatives of keratin.—Keratin is not digestible by either gastric 
or pancreatic juice. By heating with water to 150°—200° C. it dissolves, 
forming a turbid solution. It dissolves more readily in alkalis; the 
solution contains alkaline sulphides, and substances of the proteose class, 
called keratinoses by Krukenberg.® 

The decomposition products of keratin obtained by the use of acids 
are like those of the proteids, and include leucine, a good deal of tyrosine 
(1-5 per cent.), aspartic acid,!° glutaminic acid, ammonia, and sul- 
phuretted hydrogen, lysine,” lysatinine,” and a sulphur-containing sub- 
stance * which forms a compound with hydrochloric acid, with the 
formula C,,H,.N,O,SCl,. Drechsel 1° considers that some of the oxygen 
of the keratin is united to sulphur, and a part to amido-acid radicles. 

The close chemical relationship of keratin to proteid coincides with 
what is known as to its formation within the protoplasm of cells, for 
instance in the epidermis. The e/ecdin granules of the stratum granuloswin 
probably represent an intermediate stage in the transformation. 


1 Ann. d. Chem., Leipzig, Bd. xlv. 

2 “ Versuch. einer allgem. physiol. Chem.,” Braunschweig, 1844-51. 

° Kiihne and Chittenden, Joc. cit. 

4See Drechsel, Ladenburg’s ‘‘ Handworterbuch,” Bd. iii. Other analyses of horn have 
been made by Tilanus, Hoppe-Seyler’s ‘‘ Physiol. Chem.,” S. 90 ; Lindvall, Jahresb. wi. d. 
Fortschr. d. Thier-Chem., Wiesbaden, 1881. 

> A large number of estimations of sulphur in keratins from different sources will be 
found in a paper by Mohr, Ztschr. f. physiol. Chem., Strassburg, 1895, Bd. xx. S. 403. 
The percentage varies from 2°6 to 5°3. Diiring (ibid., 1896, Bd. xxii. S. 281) obtained very 
similar results. 

5 Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, Bd. xviii. S. 217. 

* Skandin. Arch. f. Physiol., Leipzig, Bd. iii. ~ 

8 “Physiol. Chem.,” 3rd German edition, S. 44. 

* Sitzungsb. d. Jenaisch. Gesellsch. f. Med. u. Naturw:., 1886. 

1” Kreusler, Journ. f. prakt. Chem., Leipzig, Bd. evii. 

1 Horbaczewski, Sitzwngsb. d. k. Akad. d. Wissensch., Wien, Bd. |xxx. 

2 Hedin, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1893, Bd. xxii, 

3 Loc. cit. 


74 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


Amyloid Substance.-—This material, also called Jardacein, occurs in 
disease in the form of degeneration, called waxy, albuminoid, amyloid, or 
lardaceous. It principally affects small blood vessels, but it may involve 
the tissue elements of organs. The degeneration occurs specially in 
cases of chronic pus formation, and is frequently a sequela of syphilis. 
The name amyloid was given to it, because the substance is coloured 
brownish red by iodine, and was supposed by Virchow to be of 
carbohydrate nature. Friedrich and Kekule! were the first to show 
that it 1s nitrogenous, and gave as its percentage composition, C, 53°6 ; 
H,7; N, 15; O, 244. It also contains 1:3 per cent. of sulphur.” 
On decomposition it yields leucine, tyrosine, and the other products 
usually obtamed from albuminous matter, but no sugar or other 
reducing substance. By boiling with alkali a chitin-lke residue is left.’ 
It is slowly soluble in gastric juice.* 

Skeletins.—This term is applied: by Krukenberg® to a number of 
nitrogenous substances found in the skeletal tissues of invertebrates. 
They are characterised by great insolubility, and are probably all 
amido-derivatives of carbohydrates. Under the term are included 
chitin, conchiolin, spongin, cornein, fibroin, and sericin. 

Chitin.—This substance forms the chief constituent of the ectodermal 
skeletal tissues of invertebrate animals, especially of arthropods.© In 
erustacea it is often impregnated with calcareous matter, and in the 
odontophore of molluses with silica. According to Krawkow,! it is in 
union with a proteid-lke substance. Gibson,$ Winterstein,® and 
Escombe !° have found chitin instead of cellulose in several fungi. 

It is prepared from the wing-cases of beetles by boiling them with 
caustic soda. The chitin remains insoluble; it may be dissolved in cold 
concentrated hydrochloric acid, and precipitated unchanged from this 
solution by the addition of water. It is colourless, amorphous, insoluble 
in water, aleohol, ether, acetic acid, dilute mineral acids, and concen- 
trated solutions of the alkalis. It is soluble in concentrated mineral acids. 

The formula and constitution of chitin are differently given by 
different observers. Ledderhose™ gave it the formula C,,H,,N,O,p. 
Berthelot * stated that it yields a fermentable sugar on boiling with 
sulphuric acid. Sundwik ® gave it the formula “CorHiooNs O.,+nH,O 
(x varying from 1 to 4), and considered it to be an amine derivative of 
a carbohydrate with the formula (C,,H,,0,)), Kyvawkow ™ considers 


1 Virchow’s Archiv, Bd. xvi. S. 58. 2 Kiihne and Rudneff, zbid., Bd. xxxiil. 

3 Krawkow, Centralbl. f. d. med. Wissensch., Berlin, 1892. The resemblance to chitin is 
supported only by its behaviour to staining agents like iodine. There is no true chemical 
resemblance between the two substances. Amyloid substance, for instance, yields no gluco- 
samine (Cohn, Ztschr. f. physiol. Chem.. Strassburg, 1896, Bd. xxii. S. 153). 

4 Kostiurin, Wien. med. Jahrb., 1886, 8. 181. See also Tschermak, Ztschr. f. physiol. 
Chem., Strassburg, 1895, Bd. xx. S. 343. 

5 Ztschr. f. Biol., Miinchen, Bd. xxii. 8S. 241; ‘“‘Grundziige einer vergl. Physiol. d. 
thier. Geriistsubstanz,”” Heidelberg, 1885. 

6 Gamgee (‘‘ Physiol. Chem.,” vol. i. p. 299) gives a list of the situations where chitin 
has been described or inferred to exist. To these must be added the pen of cuttle-fishes 
(Krukenberg, Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. xviii. S. 989) ; and the cartilages 
and other mesoblastic structures of the sepia and king crab (Halliburton, Proc. Roy. Soc. 
London, vol. xxxviii. p. 75). 

7 Ztschr. f. Biol., Miinchen, Bd. xxix. 8 Compt. rend. Acad. d. se., Paris, tome cxx. 

® Ber. d. deutsch. chem. Geselisch., Berlin, 1894 and 1895. 

 Ztschr. f. physiol. Chem., Strassburg, 1896, Bd. xxii. S. 288 

Ml Toid., Bas iS. 21373 ives. se: 

Compt. rend. Acad. d. sc., Paris, tome xlvii. p. 227. 

8 Ztschr. f. physiol. Chem., Strassburg, Bd. v. 14 Toc. Gite 


Ee 


SKELETINS. 75 


that there are a number of chitins, amine derivatives of different 
carbohydrates (dextrose, glycogen, dextrin, etc.); they give different 
colour reactions with iodine! Ledderhose? was the first to show that 
the reducing substance obtained by the action of mineral acids in 
chitin is not sugar but glucosamine (see p. 9). The equation re- 
presenting its decomposition he gives as follows :— 


2C.;H;,N,O,, + 6H,0 =4C,H,,NO,+30,H,0, 


(chitin) (water) (glucosamine) (acetic acid) 


Glucosamine is an amido-derivative of glucose ; it forms crystalline 
salts, of which the hydrochloride is readily prepared by boiling chitin 
with hydrochloric acid; this is soluble in water, and is dextrorotatory 
(«),—=+70°6. The base is prepared by the action of baryta on the 
sulphate. It is crystalline and not fermentable with yeast. 

Schmiedeberg* looks upon chitin as an acetyl derivate of glucosamine, 
and as he has also obtained the latter substance from the chondroitin- 
sulphuric acid of cartilage, he regards it as indicating a connection 
between the skeletal tissues of vertebrate and invertebrate animals. 

By heating chitin with ten times its weight of caustic alkali at 180°, 
Hoppe-Seyler and Araki* obtained a substance which possesses the 
original form of the pieces of chitin, but differs from chitin in being 
very soluble in dilute acids such as acetic acid ; from such solutions it is 
precipitable by alkalis. This substance is called chitosan, and its forma- 
tion from chitin is shown in the following equation :— 


C,3H5)N,0,5 al 2H,0 —— C,,HoN.010 +2 C,H,0O, 


(chitin) (water) (chitosan) (acetic acid) 


Chitosan in dilute acetic acid is levorotatory ; («),=—17°7 to 17°°9. 
By heating it with acetic acid in sealed tubes to 155°, a substance 
very like chitin is regenerated; it, however, contains three, whereas 
true chitin only contains two acetyl groups. 

By boiling with concentrated hydrochloric acid, chitosan yields 
hydrochloride of glucosamine, formic and acetic acids. 


Neurochitin.—In crustacea, chitin has been said to take the place of neuro- 
keratin as a support to the nerve fibres.? 

Conchiolin (C)H,,N,O0,,) forms the organic basis of the shells of mussels 
and snails. On decomposition it yields leucine, perhaps glycocine, but no 
tyrosine or reducing substance. It does not give the xanthoproteic, Millon’s, 
nor the Adamkiewicz reactions. The byssus of molluscs is similar. The 
cementing substance between the eggs of various molluscs contains a substance 
more like keratin. Cornein, from corals (C,,H,,N,O.;), differs from conchiolin 
by giving a red colour with Millon’s test ; on decomposition it yields leucine 
and a crystalline material called cornicrystallin. 

Spongin, the organic basis of the common sponge, yields as decomposition 
products, leucine and glycocine (Stideler), but no tyrosine.’ It does not give 
the colour reactions just mentioned; it resembles conchiolin by yielding 

1H. Zander (Arch. f. d. ges. Physiol., Bonn, 1897, Bd. lxvi. S. 545) also finds that 
chitin gives a colour with iodine very like that given by glycogen. 

2 Zischr. f. physiol. Chem., Strassburg, Bd. ii. S. 213; iv. S. 137. 

3 Arch. f. exper. Path. u. Pharmakol., Leipzig, Bd. xxviii. 

4 Ber. d. deutsch. chem. Gesellsch., Berlin, 1894, Bd. xxvii. S. 3329 ; 1895, Bd. xxviii. S. 
82; Ztschr. f. physiol. Chem., Strassburg, 1895, Bd. xx. S. 498. 

> Griffiths, Compt. rend. Acad. d. sc., Paris, tome exv. 

6 Zalocostas (ibid., tome cvii. p. 252), however, obtained tyrosine, butalanine, and 
glucalanine (C;H,,N.0,). 


76 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


peptone-like materials on digestion, which differ from true peptones and 
proteoses by not giving the colour reactions in question. 

Fibroin is the substance of which spiders’ webs are composed. It 
is insoluble except in concentrated mineral acids and alkalis. It yields on 
decomposition glycocine, leucine, and tyrosine, and gives the proteid colour 
reactions. This substance and sericin, a similar material (which, however, 
gives no glycocine on decomposition), are found together in silk.!_ _Hammarsten # 
gives the following table of percentage compositions :— 


C H N Ss O 

Conchiolin . 50°92 6°88 17°86 0°31 24°34 Krukenberg.® 
Spongin . 46°5 6:3 16-2 0-5 27-5 Crookewitt.* 

5 . 48°75 6°35 16-4 de chs Possell.® 
Cornein . 48°96 5:9 16°81 is 28°33 Krukenberg. 
Fibron =. 48°23 6:27 18:31 {hess 27°19 Cramer.® 

- . 48:3 6°5 19-20 al 26:0  Vignon.7 
Sericin . 44°32 618 18-30 a 30°2 Cramer. 


INORGANIC COMPOUNDS. 


Water forms about 585 per cent. of the weight of the body ; 
in infants it is 66-4 per cent. An adult takes in food 2,500 ec. of 
water daily, and excretes rather more, as some is formed in the body 
by the oxidation of hydrogen. 

Hydrogen peroxide is stated by Wiirster® to be given off in various 
situations; he uses tetramethyl-paraphenylenediamine papers to detect 
it. 

Hydrogen sulphide occurs in small quantities as the result of putre- 
factive changes in the alimentary canal. 

Ammonia is also formed in putrefactive processes, and in pancreatic 
digestion. A small quantity occurs in fresh urine, and increases when 
the urine putrefies. 

Hydrochloric acid occurs in gastric juice. 

Carbonic acid occurs in the blood, lymph, and secretions. 

The acids found in the body are, however, usually in combination as 
salts. 

Salts.—The chief salts found are the chlorides of sodium and potassium, 
the sulphates of the same metals, phosphates of sodium, potassium, 
calcium, and magnesium, carbonates of sodium and calcium. Bone, 
dentine, and enamel are chiefly rich in calcium salts, especially the 
phosphate. Other solid tissues are especially rich in potassium salts. 
In the fluids (milk excepted) the most abundant salt is sodium chloride. 


A fuller consideration of the various saline constituents will be taken with 
the individual tissues and secretions. The following general tables may be, 
however, quoted here;* the figures give percentage quantities of mineral 
matters in the ash :— 


1 Weyl, Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. xxi. S. 1407, 1529. 

2 “« Physiol. Chem.,” 3rd German edition, S. 49. 

3 Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. xvii. 

4 Ann. d. Chem., Leipzig, Bd. xlviii. 5 Ibid., Bd. xly. 
5 Journ. f. prakt. Chem., Leipzig, Bd. xevi. 

* Compt. rend. Acad. d. sc., Paris, tome exy. 

8 Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. xix. S. 3195 ; xx. S. 263, 1033. 

* From Beaunis, ‘* Physiologie humaine.” 


_—————- 


INORGANIC COMPOUNDS. 77 


TISSUE . - acl Bone. Calf-muscles. Brain. Liver. Lungs. Spleen. | 
ANALYST Heintz. Staffel. Breed. Oidtmann C. Schinidt. | Oidtmann. 
Sodium chloride. 10°59 4°74 ob 13°0 vee 
Soda . 2°75) 10°69 LAr 5 Te A lee 1925 44°33 
Potash ; Bae 34°40 34°42 Zoe. | 1°3 9°60 
Lime . : Ll ee BERT 1°99 0°72 Sie ole S18 7°48 
Magnesia : : 1°22 1°45 1-23 0°20 1°9 0°49 
Ferric oxide : i a4 ot: 2°74 3°2 7°28 
Chlorine . : ve te - 2°58 a 0°54 
Fluorine su 1°66 | ses es ae im 
Phosphoric acid. | 53°31 48°13 48°17 50°18 48°5 27° 10 
| Sulphuric acid. | 52 “ | 0°75 0°92 Avy cr) ltgy, 2204 
Carbonic acid . | 5°47 i i Se 
Silicie acid . : he 0°81 aly 0°27 0-17 
FLUID . - : Blood. | Serum. Blas. Lymph. | Urine. | Milk. Bile. | ees 
ANALYST % . | Verdeil. | Weber. | Weber. Datine Porter. | "stein. | Rose. | Porter. 
Sodium chloride 5881 | 72°88 | 17°36 74°48 | 67°26 | 10°73 | 27°70 4°33 
Potassium ,, , ei na) MBS! 237) Pe Au 2O6S3i iil GT ees 
Soda . 4°15 12°93 3nd 10°35 | 1°33 Fe. 36573 |, 5:07 
Potash 11°97 2°95 22°36 3°25 | 13°64 | 21:44 | 4°80 | 6°10 
Lime . 1°76 2°28 2°58 0°97 Vb | 18°78 1°43 | 26°40 
Magnesia 1°12 0°27 0°53 0°26 | 1°34 | 0°87 | 0°53 | 10°54 
Ferric oxide : 8°37 0°26 10°43 0°05 i O10.) 0°23 2°50 
Phosphoric acid . | 10°23 uly /B3 10°64 ¥:09 | 11°21 | 19°00 | 10°45 | 36°03 
Sulphuric acid 1°67 2°10 0:09 ef 2°64 | 6°39 
Carbonic acid lei 4°40 | 2°17 | =8°20 ia | 11°26 Sv 
Silicic acid . 0°20 0°42 0°42 4°06 036 | 313 


Sodium and potassium salts.— Probably 200 grms. may be taken 
as an average amount of sodium chloride (common salt) in the adult 
human body. It is a most important food, and about 16 grms. are 
daily excreted in the urine, and smaller amounts in the sweat and 
feces. If potassium chloride be substituted in the food for the sodium 
salt, disturbances arise from deficiency of the latter. The tissues, how- 
ever, retain common salt very tenaciously, so that during a dietary 
devoid of salt it disappears slowly from the urine. 

During its passage through the body, it facilitates the absorption of 
proteid food, and increases tissue metabolism. The following table? gives 
the probable relative amounts of sodium and potassium chlorides in 
parts per thousand :— 


NaCl KCl NaCl KCl 
Blood ' ‘ 2°70 2:05 | Pancreatic juice 
Blood corpuscles 2 oom (from tempo- 
Plasma. : 5°54 0°35 rary fistula) 7°35. 0:02 
Lymph . : 567) -eitGastime juice; jo. 1:45 0°55 
Chyle : : 584... | Bile . : : 5:33 0:28 
Pancreatic juice Milk . ; : 0-87 2°13 
(from perman- Urine , . 11:00 4°50 
ent fistula) 2°50 0°93 


Bunge found that the soda salts are more abundant in embryonic 


1 Vierordt’s ‘‘ Daten u. Tabellen,” 1893, Aufl. 2, S. 122. 
2 From M‘Kendrick’s ‘‘ Text-book of Physiology,’”’ Glasgow, 1888, vol. i. p. 39. 


78 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 


and early life than in adult life. This is illustrated by the following 
table :— 


4 


MaRMY LE: Ort | Na,O K,O 
Rabbit’s embryo. 2°183 2°605 Cat 29 days old 2:292 2°684 
Rabbit 14 daysold 1:630 2-967 Dog 4. Sevier 27589 2°667 
Kitten] day ,, 2°666 2-691 Adult mouse. . 1°700 3-280 
Cat 19 days ,, 2°285 2°790 


This fact is probably due to the larger amount of cartilage (rich in 
soda salts) and the smaller amount of muscle (rich in potash salts) in 
early life as compared with the adult condition. 

Various phosphates of sodium and potassium are found in the blood, 
lymph, urine, and other secretions. 

Sodium carbonate and bicarbonate occur in the food, and originate 
in the body from the salts of vegetable acids (tartaric, citric, etc.). 

Sodium and potassium sulphate exist in smaller quantities in the 
body. Only minute quantities of these salts are introduced with the 
food; they are chiefly formed by the oxidation of proteids and other 
organic substances containing sulphur. 

Ammonium salts—Minute traces of ammonium chloride are found in 
the urme. The urine of reptiles and birds is largely composed of 
ammonium urate. Small quantities of this salt, and also of ammonio- 
magnesic phosphate, are found in human urme. Ammonium carbonate 
is formed from urea in decomposing urine. 

Calcium salts—About three-quarters of the total mineral solids in 
the body consist of calcium phosphate, Ca,(PO,),; this is because of the 
great preponderance of this salt in bone. Other calcium salts occurring 
in bone, dentine, and enamel are the carbonate, sulphate, and fluoride. 
Calcium phosphate, urate, and oxalate, are found in the urine. Most 
tissues contain small quantities of the phosphate and carbonate. Egg 
shells, the shells of crustacea, coral, and otoliths consist chiefly of 
carbonate of lime.? 

Magnesium salts—Magnesium phosphate (Mg,(PO,),) occurs in the 
tissues along with the calcium phosphates (Ca,(PO,), and CaH,(PO,),) 
but in smaller amount. It occurs also in the urine. Ammonio- -magnesium 
or triple phosphate (NH,MgPO,+6H,0) is also often found in “decom- 
posing urine. Magnesium palmitate and stearate are found in the feces. 

Tron is an important constituent of the blood pigment. The blood 
of an adult contains 3 grms. of iron. Small quantities are found in 
other liquids of the body (chyle, lymph, bile, milk, urine, gastric juice) ; 
it is also contained in the black pigment of the skin and hair, and of 
melanotic sarcomata. A small quantity of ferric sulphide is found in 
the feces, and small quantities of iron are found in both liver and 
spleen.’ It is present in the tissues in organic combination with nuclein 
(see p. 68). 

Copper is found in two proximate principles, hemocyanin, the blue pig- 
ment of the blood of many invertebrates (crustacea, cuttle-fishes, scorpions, 
ete.), and in the pigment, turacin, of birds’ feathers. Small quantities of this 
metal, and also of aluminium, manganese and lead, may occur accidentally in 

1 Bunge, Ztschr. f. physiol. Chem., Strassburg, Bd. xiii. 8. 899. 
: € On excretion and absorption of lime see Rey, Chem. Centr.-Bi., Leipzig, 1895, Bd. ii. 
i Thor tithe concerning the amount of iron in foods, see Stockman, Journ. Physiol., 


Cambridge and London, 1895, vol. xviii. p. 484; 1897, vol. xxi. p. 55. An ordinary 
daily diet contains 9-10 mgrins. of iron. 


INORGANIC COMPOUNDS. 79 


other parts, being taken in with the food,! and not excreted at once with the 
feeces, but deposited in some tissue or organ. Drugs and poisons (mercury, 
arsenic) may be similarly deposited. 


Silica.—A minute quantity of silica exists in the blood, urine, bones, 
hair, and other parts. 

Phosphates—The amount of phosphoric acid given in analyses of 
the ash of animal structures is not always correct, since a certain 
quantity is obtained during the process of incineration, from the decom- 
position of organic compounds, which, like lecithin, contain phosphorus. 

The phosphoric acid which occurs in mineral compounds in the body 
is derived in part directly from the food, and in part from the metabolism 
of lecithin and nuclein. It unites with soda, potash, lime, and magnesia 
to form the various phosphates already alluded to. An adult man 
eliminates by the kidneys 2°5 to 3°5 grms. of phosphoric acid daily. 
Carnivora eliminate phosphates chiefly by the kidneys, herbivora chiefly 
with the feces. 

Carbonates.—The presence of carbonates in the ash of animal matters 
is partly derived from the decomposition of organic compounds. 
Alkaline carbonates and bicarbonates are, however, found in blood, 
urine, lymph, saliva, etc. 

Sulphates—These also may be partly formed during the process of 
incineration, from proteids and other organic compounds containing 
sulphur. The sulphuric acid in the urine is in part combined as ordinary 
sulphates, in part as ethereal sulphates. It is derived to a small extent 
from the food, but chiefly from the metabolism of proteids, the amounts 
of sulphuric acid and urea in the urine running parallel. 


1 Karl B. Lehmann (Arch. f. Hyg., Miinchen u. Leipzig, Bd. xxiv. S. 1, 18, 72) 
states that in an ordinary diet we take 20 mgrms. of copper daily, and if preserves are much 
used, it may rise to over 300 mgrms. per diem ; more than 120 mgrms. appears to be harmful. 


THE CHEMISTRY OF THE TISSUES AND ORGANS. 
By W. D. HALLIBURTON. 


ContEents.—Cells and Protoplasm, p. 80; Liver, p. 85; Spleen, p. 87; Thymus, 
p- 88; Thyroid, p. 88; Suprarenals, p. 90; Pancreas, p. 92; Kidneys, p. 
92; Testis, p. 92; Muscle, p. 95; Skeletal Tissues, p. 111; Nervous Tissues, 
p. 115; The Eye, p. 121; Milk, p. 125. 


THE preceding article contains an account of the principal proximate 
principles occurring in the body and in food. 

In the present article I propose to present the subject from another 
standpoint, and to discuss the chemical composition of the various 
animal tissues and organs. ‘This will in great measure be complemental 
to what has been already done, and will give the opportunity of describ- 
ing some substances which have only been treated incidentally in the 
foregoing chapter. 

In describing the chemistry of the organs, I shall endeavour to avoid 
discussions as to their metabolic functions, and shall omit all considera- 
tion of their secretions, since these are treated elsewhere in this work ; 
an exception, however, will be made in the case of milk. 

Protoplasm and cells.—The chemical structure of living substance 
is still beyond our knowledge. All that chemists are able to do is to 
examine the disintegration products of the substance which they un- 
avoidably kill by the use of reagents. 

Some authors speak of living substance as if it were merely proteid 
in composition, and have adopted the phrase “ living proteid ” (see p. 38). 
But it is doubtful if the use of such a term is justifiable, for proto- 
plasm even in its simplest condition invariably contains, or yields on 
disintegration, substances other than proteid, though proteids and 
compound proteids like nucleo-proteid are by far the most abundant of 
these disintegration products. Among the other solid substances con- 
stantly present in protoplasm are lecithin, cholesterin, and inorganic 
salts (especially phosphates and chlorides of calcium, sodium, and 
potassium); and frequently fat and carbohydrate material, such as 
glycogen, are also to be found. Water occurs to the extent of 75 per 
cent. or more. Whether these substances are all present in the free 
state, or, as is much more probable, are linked together in intimate 
union, to form the complex protoplasmic molecule, it is at present 
impossible to say with certainty. Living cells are alkaline; after death 
they become acid. 

The simplest form of protoplasm known is that found in the 
plasmodium of the myxomycetous fungus, Athalium septicum. It has 


OF Serre aS 


Cae 


Sea 


PROTOPLASM AND CELLS. 81 


been analysed by Reinke! and Krukenberg,” and their observations con- 
firm what has just been stated. 

The nucleus of cells, the study of which began with the work of 
Brunton, Plosz, and Miescher, has of recent years been very thoroughly 
worked at by Hoppe-Seyler, Kossel, and numerous other physiological 
chemists ; the result will be gathered from the section in the preceding 
chapter on nuclein, and, as will be there seen, there are yet many gaps 
in our knowledge which require to be filled up. 

The proteids obtained from the cell protoplasm have been examined 
in simple cells such as those of lymphoid tissue, and in the more special- 
ised cells of secreting organs, such as the liver, kidneys, testis, and so forth. 
The main result is the same in all, though there are minor differences 
between individual cases. 

The proteid contained in greatest abundance is nucleo-proteid ; small 
quantities of globulin usually coagulating at the low temperature of 
50° C. or even “lower, and minute traces of. an albumin are also found. 

The nucleo-proteids from different cells differ in the amount of 
nuclein (as evidenced by the percentage of phosphorus) they contain.* 


The nucleo-proteid from the thymus contains 0°8 per cent. of phosphorus. 
” ” kidney ” 0°37 ” ” 
” ” liver ” 1-45 ” ” 
- a brain FS 05 As 3 
a 43 red marrow ,, 1°6 ¥ ; 
,, red corpuscles ,, 0°68 , $5 
Schmidt’s fibrin ferment 1:25 


+B) 


In my early work‘ on the proteids of cell protoplasm, I selected the 
cells of lymphatic glands, because one can obtain from these structures 
an abundant supply of comparatively simple cells; later, | found that 
the cells of thymus® gave similar results. At first I described the pro- 
teids obtained as four in number, namely nucleo-proteid, cell globulin-«, 
cell globulin-8, and cell albumin. The nucleo- proteid can be obtained 
either by Wooldridge’s acetic acid method or by the sodium chloride 
process (p. 68). 

The material obtained by both methods is the same, though they 
differ in their physical condition; that obtained by the sodium chloride 
process being more viscous than that b by Wooldridge’s method. That 
they are the same is shown by the facts that both give the same re- 
actions, which closely resemble those of elobulins ; both contain 
practically the same amount of phosphorus, and both produce intra- 
vascular coagulation.® 

The term cell globulin was originally introduced by me as a con- 
venient designation for the proteids which are coagulable by heat in 
sodium sulphate extracts of the cells. The nucleo- proteid just men- 
tioned is viscid when extracted by sodium chloride and magnesium 
sulphate, but an extract with sodium sulphate solution does not exhibit 


1 «¢Studien ueber das Protoplasma,” Berlin, 1881. 

2 Untersuch. a. d. physiol. Inst. d. Univ. Heidelberg, 1882, Bd. ii. S. 273. 

3 Halliburton, Journ. Physiol., Cambridge and London, 1895, vol. xviii. p. 306. 

4 Proc. Roy. ‘Soe. London, 1888, vol. xliv. p- 255; Journ. ’ Physiol. Cambridge and 


London, 1888, vol. ix. p. 229. 5 Ibid., vol. xviii. p. 306. 
6 Halliburton and Brodie, zbid., 1894, vol. xvii. p. 135. 
VOL. 1.—6 


82 THE CHEMISTRY OF THE TISSCES AND ORGANS: 


viscidity, and it was the absence of this character which led me to the 
erroneous conclusion that no nucleo-proteid had gone into solution. 

The sodium sulphate extract contains two proteids, one which co- 
agulates at 48°-50° C., the other at 75° C. The first, which I called cell 
elobulin- a,is really a elobulin ; it yields no nuclein on gastric digestion ; + 
but the second, which I called cell globulin-8, though like a globulin i in its 
solubilities, is really the same nucleo-proteid which ‘by: treatment with 
other salts is rendered viscid.2 That this substance is related to, if not 
identical with, the fibrin ferment or its zymogen (Pekelharing) has been 
rendered probable by the researches of Pekelharing and myself. 

The albumin is only present in minute quantities ; its properties are 
like those of serum albumin, and it may partly arise from blood or 
lymph imperfectly washed away from the cells. 

Proteoses and peptone, when present, are the result of post-mortem 
changes, or of manipulations during the processes employed in separating 
the other proteids. 

Myosin is absent. 

Lilienfeld® has carried out a similar research on the chemistry of 
cells which he obtained from the thymus, by the usual means of pressure 
and the centrifuge. He found a proteid corresponding to cell globulin-« 
coagulating at 48° C., and another corresponding to cell albumin 
coagulating at 73—75° C. The nucleo- ee oteid which he obtained by my 
sodium chloride process contained C, 55-46; H, 7-64; N, 15°57, and P, 
0-453 per cent. The alcoholic extract of the cells contained protagon, 
Benito aleric acid, inosite, and monopotassium phosphate. 

By Wooldridge’ s method he obtained the nucleo-proteid he has 

ealled “nucleo-histon ” (see p. 68), and he considers that this, in part at 
any rate, is derived from the nuclei. Its percentage composition is C, 
48-46; H, 7:0; N,16°86; P,3:025; and S,0°701. The action of artificial 
gastric juice, or of 0:8 per cent. hydrochloric acid, on this, is to separate 
the nuclein from the proteid, which goes into solution as peptone. The 
nuclein contains 4991 per cent., and the nucleic acid prepared from 
this 9°94 per cent., of phosphorus. 

In the following table he gives the quantitative composition of 
leucocytes :— 


Water . , 4 2 : 4 : : . 88:dik 
Solids . ; F , : ; . , Be te 


One hundred parts of the solids contain— 


Total phosphorus . : : : ‘ ; mv 0! 
Total nitrogen. , : ; : d . (T6038 
Proteid ‘ ‘ : ; : ‘ : . pleas 
Nuclein ; . 68°78 
Histon (i.e. proteid part of the nucleo- proteid) .| Ise 
Lecithin. : : : : ; f - Se 
Fat 7. ; ; : ; ; ; . 4:02 
Cholesterin . : : § : i : . 4:40 
Glycogen. : : : : : : »  O6G 


1 Halliburton, Journ. Physiol., Cambridge and London, 1892, vol. xiii. p. 806. 
2 Ibid., 1895, vol. xviii. p. 312. Pekelhari ing showed this also to be the case, 
3 Zischr. f. physiol. Chem., Strassburg, Bd, xviii. 8. 473. 


PROTOPLASM AND CELLS. 83 


The high percentage of phosphorus in the nucleo-proteid obtained by this 
method is certainly not in accord with the observations of Brodie and myself. 


We are justified in concluding from this work that the colourless 
corpuscles of the blood which originate from lymphoid structures have a 
similar composition. It is, however, impossible to investigate the actual 
colourless blood corpuscles by macrochemical methods. Microchemically 
they can be shown sometimes to contain fat and glycogen.* 

Pus cells are colourless corpuscles, which show a considerable amount 
of fatty degeneration and are generally dead; these have been the subject 
of several researches. The nuclei consist of nuclein, which is historically 
interesting, because this was the first preparation made by the method of 
gastric digestion (Miescher).” 

The protoplasm consists of proteids chiefly, but it also yields ex- 
tractives and inorganic salts. Hoppe-Seyler’s analysis of two samples of 
dried pus cells give the following percentage results :— 


iE Te 
Proteids ee il sero | 
Nuclein : : oA i OOO 67°369 
Insoluble substances 20566 j 
Lecithin | es { 7-564 
Fats | eee | 7500 
Cholesterin . , 2 7-400 7-283 
Cerebrin } : : 5199 
eemicavecus i Lan 1-433 yee 

Inorganic constituents in one hundred parts of dried pus corpuscles— 

PEO eybel)i0)- .0unndi OBB BOs ator wa O96 
Ca.,(PO,). : . 0:205 Na . ‘ . 0-068 
Mg,(PQ,), ‘ » OL DBs i Key) 3 : . traces. 
BE(EO,) 5 — | 0106 


Proteids of pus.—Boedecker? asserted that pus occasionally contains 
gelatin and chondrin in addition to proteids, and a crystalline acid he 
termed chlorrhodinic acid, but Miescher was unable to confirm these 
results; Miescher was also unable to find any myosin, a substance pre- 
viously supposed to exist in the cell protoplasm. 

My own observations coincide with those of Miescher on this point, 
and also show that the most abundant proteid is nucleo-proteid. In 
fact, the proteids obtained from pus are practically the same as those from 
the thymus and other lymphoid structures. 

Fibrin ferment was prepared from pus by Rauschenbach.* Consider- 
able quantities of proteoses and peptone are generally found in pus, and 
are doubtless produced during the retrogressive metamorphosis of the 
corpuscles. The original statement that pus contains peptone was made 
by Eichwald® and Hofmeister.6 Though the method they employed 
was not perfectly trustworthy, S. Martin? showed that they were right 
in their conclusions. He placed pus under alcohol for many weeks, 

1 Schafer, ‘‘ Course of Practical Histology,” London, 1876, p. 39. 

* Hoppe-Seyler’s ‘‘ Med. Chem. Untersuch.,” 1871, Heft 4, S. 497. 

° Zischr. f. rat. Med., Leipzig, N.F., Bd. vi. 

4 Inaug. Diss., Dorpat, 1883 ; Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden Bd. 
xiii. S. 134. 

3 Verhandl. d. phys-med. Geselisch. zu Wiirzburg, 1864, 8. 335. 

6 Zischr. f. physiol. Chem., Strassburg, 1864, Bd. ii. S. 295. 

* Brit. Med. Jovrn., London, 1890, vol. ii. p. 234. 


84. THE CHEMISTRY OF THE TISSUES AND ORGANS. 


and then dried it and extracted it with water. Proteoses and peptone 
went into solution, the other proteids having been coagulated. It is pro- 
bable that some of the symptoms which accompany the suppurative pro- 
cess is produced by the entrance of these substances into the cireulation.t 

There is little to add concerning the other constituents of pus cells. 
The large increase of fat, lecithin, and cholesterin confirms the fact of 
fatty degeneration, evident to the microscope; free fatty acids may even 
be found in old pus, forming crystalline deposits. 

Glycogen can often be demonstrated in pus corpuscles micro- 
chemically by the use of iodine;? Salomon? separated it from the cells 
in appreciable quantities. 

Pigments (pyocyanin, pyoxanthose) are frequently found in pus, and 
are produced by chromogenic bacteria (Fordos, Liicke, Fitz, Kunz, 
Babes). 

The proteids of red marrow cells——In the lymphatic glands and 
thymus the cells are non-eosinophile ; in the red marrow the cells are 
mostly eosinophile. Sherrington® showed that the eosinophile granules 
give microchemically the reaction for phosphorus, introduced by Lilienfeld 
and Monti;® the cells themselves were investigated macrochemically by 
J. R. Forrest.’ The marrow used was obtained from the interior of 
rabbits’ femora and horses’ ribs. 

His results were very like those obtained from other cellular 
structures. Two proteids only were obtainable in any quantity, these 
were a cell globulin, coagulating at 47°-50°, and a nucleo-proteid. The 
latter contaims a high percentage of phosphorus,’ namely, 1°6. Heemo- 
globin is present in small quantities, and proteose and peptone are absent. 

Epithelium.—Our knowledge of the tissues included under the 
heading epithelium is principally histological. There is no reason to 
suppose that the proteid constituents of the protoplasm and nucleus are 
in any way different from that found in cells generally. 

Mucin is formed in many situations, both in the cells of mucous 
glands and in goblet cells. It is also the principal constituent of the 
cementing material between the cells. 


Mucus is the name given to the secretion which owes its sliminess to. 
mucin. Mucus also contains epithelial cells, more or less disintegrated, and a 
few leucocytes. It has an alkaline reaction, and contains a certain small pro- 
portion of proteids, extractives, and salts, similar to those of the blood. In 
some cases, the mucinoid material in secretions is really a nucleo-proteid. 
Thus, in the bile of some animals like the ox, there is very little true mucin, 
but the viscidity is almost entirely due to nucleo-proteid ;* in human bile, on 
the other hand, the viscid material is mucin, very little nucleo-proteid being 


1 Ott and Collmar, Journ. Physiol., Cambridge and London, vol. viii. p. 218 ; Krehl 
and Matthes, Deutsches Arch. f. klin. Med., Leipzig, 1896, Bd. liv. S. 501; Arch. f. exper. 
Path. u. Pharmakol., Leipzig, 1896, Bd. xxxvi. S. 487. 

2 Ranvier, Progrés méd., Paris, 1877, p. 422. 

° Deutsche. med. Wehnschr., Leipzig, 1877, No. 35. 

4 Compt. rend. Acad. d._sc., Paris, 1860, tome li. p. 215; Arch. f. klin. Chir., 
Berlin, 1862, Bd. iii. S. 125; Quart. Journ. Micr. Se., London, Jan. 1880, p. 106; 
Monatsh. d. Chem., Wien, Bd. ix. S. 361; Compt. rend. Soc. de biol., Paris, 1889, 
9. 438. 

76 Proc. Roy. Soc. London, 1894, Bd. lv. p. 161. 

5 Zischr. f. physiol. Chem., Strassburg, 1893, Bd. xvii. S. 410. 

7 Journ. Physiol., Cambridge and London, 1894, vol. xvii. p. 174. 

8 Halliburton, 2bid., 1895, vol. xviii. p. 307. 

® Paijkull, Zéschr. f. physiol. Chem., Strassburg, Bd. xii. S. 196. 


GLANDULAR ORGANS. 85 


present.! The mucus of urine has also been stated to be nucleo-proteid in 
nature.” _K. A. H. Morner® investigated healthy human urine ; each experiment 
necessitated the use of 80-90 litres. He found proteid or proteid-like materials 
partly in suspension in the ordinary mucous cloud or nubecula, and partly in 
solution. From the nubecula he separated a specific member of the mucin 
group, which he calls urine mucoid. This probably originates from the mucous 
membrane of the urinary passages. It contains C 49:4, N 12°74, and 
S 2°3 per cent.; and in its general properties agrees with ovo-mucoid pretty 
closely (see p. 63). The soluble proteid in urine, which is present in the 
merest traces, is chiefly serum albumin, but some is precipitable by acetic 
acid, and this part consists of a nucleo-proteid; precipitated with it was 
found a small quantity of chondroitin sulphuric acid (see “ Cartilage” ). 

The mucin of the respiratory passages has been investigated by F. Muller.* 
He finds it is true mucin, not nucleo-proteid. It yields from 25 to 32 per cent. 
of reducing substance. This is a nitrogenous derivative of a hexose, and is 
probably glucosamine. 

Keratin and the skeletins are epithelial products which have already been 
described (p. 72). The enamel of teeth, although epithelial in origin, will 
be taken with the skeletal tissues. The epithelium of secreting glands will 
be studied with those glands and their secretions. 


GLANDULAR ORGANS. 


The liver.—The fresh liver is alkaline in reaction, but after death 
soon becomes acid from the development of sarcolactic acid. 

The number of organic substances in the liver is very numerous. 
There are proteids and nuclein from the hepatic cells; there are 
substances like glycogen, sugar, and fat, stored up within the cells, or 
produced from stored-up substances. Gelatin and mucin are obtainable 
from the connective tissue framework. There are also extractives like 
xanthine, hypoxanthine, and uric acid; lastly, a small proportion of 
inorganic constituents. 

The proportion of water is about 75 per cent. v. Bibra® gives the 
following numbers :— 


Water . . 76°17 percent. | Gelatin 3°37 per cent 
Insoluble tissues 9°44 ,, |  Extractives . 2°40 ,, 
Proteids . GAD. 1 af hy eats DBO! = | by. 


Proteids of the liver cells—These were first investigated by P. Plosz.° 
He found that, accompanying the onset of acidity after death, the 
liver became harder and less transparent; he therefore compared the 
condition to the rigor mortis of muscle, and sought for myosin by the 
methods Kiihne had introduced for separating muscle plasma. He did 
not, however, find any myosin. He extracted the proteids by means of 
saline solutions of various strengths, and found— 

(1) A proteid coagulating at 45° C., wholly soluble in gastric digestion ; 
(2) a nucleo-proteid, coagulating at 70° C., yielding an insoluble residue of 


1 Hammarsten, Kon. Ges. der Wiss., Upsala, 1893 (Scparat-abzug) ; Baginsky and Somer- 
feld, Verhandl. d. physiol. Geselisch., Berlin, 1894-5, Nos. 13, 14, 15 in Arch. f. Physiol., 
Leipzig, 1895, S. 362. 

2 Lonnberg, Upsala Likaref. Férh., vol. xxv.; K. Morner, Hygiea, Stockholm, 1892, 
vol. lii; Obermayer, Centralbl. f. klin. Med., Bonn, Bd. xii. 

® Skandin. Arch. f. Physiol. Leipzig, 1895, S. 332. 

+ Sitzungsb. a. Gesellsch. z. Beférd. d. ges. Naturw. zu Marburg, 1896, No. 6. 

> y. Bibra, ‘‘Chemische Fragmente ueber die Leber,” 1849. 

6 Arch. f. ‘d. ges. Physiol., Bonn, Bd. vii. S. 371 


86 THE CHEMISTRY OF THE TISSUES AND ORGANS. 


nuclein on gastric digestion; (5) a globulin coagulating at 75° C.; and 
(4) alkali albumin. 

A good many years later, I repeated these experiments; and, like 
Plosz, failed to find myosin. Myosin appears to be a specific constituent 
of muscle, and has not been found anywhere else. The hardening that 
occurs in the liver after death, and which is very slight, is possibly due 
to the solidification of the fat in the cells; though it is ‘also quite possible, 
as Plosz suggests, that if coagulation does occur in the cells with the 
formation of a myosin-like clot, this takes place so rapidly that our 
present methods do not enable us to separate its precursor from the cells. 

The proteids I obtained by the use of saline solutions were four in 
number :— 

1. A globulin (cell-globulin) coagulating at 45°-50° C. 

2. A nucleo- -proteid which coag lates at about 60° C., and is identical 
with that obtaimable by Wooldridge’ s acetic acid method from the cells. 
It contains 1-45 per cent. of phosphorus. It does not become viscous on 
admixture with neutral salts, and the sodium chloride method of 
preparing nucleo-proteids is not applicable to it. It produces intra- 
vascular coagulation. 

3. A globulin coagulating at 70° C. 

4. An albumin in mere traces, which coagulates at about the same 
temperature. 

Other organic constituents of the liver cells—Urea, uric acid (especially 
in birds), xanthine, and hypoxanthine, are found in the liver; leucine 
and tyrosine are found in cases of acute yellow atrophy, and in 
phosphorus poisoning.’ Various other substances have been described 
as occasional constituents.* 

A substance called jecorin, containing phosphorus (C,);Hy.3N;SP,0,;), 
was separated from the liver ‘by Drechsel.» In its properties 1t some- 
what resembles lecithin; it, however, reduces Fehling’s solution, which 
lecithin does not. According to Baldi,° it occurs in many other organs— 
spleen, muscle, brain, ete. 

The question of the iron-conti uning nucleins of the liver (Zaleski’s 
hepatin, Schmiedeberg’s ferratin,’ ete.) is alluded to on p. 69. The 
iron in the liver is increased in diseases, like pernicious anemia, which 
lead to increased destruction of red blood corpuscles; it is normally 
greater in young (especially new-born) animals than in older ones. 
Animals appear to enter the world with a store of iron in the liver, and 
to a less degree in the spleen, which lasts them until they are able to 
take foods other than milk, which is poor in iron.§ 


1 Journ. Physiol., Cambridge and London, 1892, vol. xiii. p. 806. 

2 Scherer, Ann. d. Chem., Leipzig, Bd. evii. S. 314 ; Cloetta, ibid., Bd. xevii. S. 282. 

® Sotnitschewsky, Ztschr. f. physiol. Chem., Strassburg, Bd. iii. 8. 391; see also 
Rohmann, Berl. klin. Wehnsehr., 1888, 8. 43 and 44. 

4 Guanine, inosite, scyllite (Frerichs and Stiideler, MWitth. d. Ziirich. natur. Gesellsch. 
1858) ; cystine (Hoppe-Seyler, ‘‘ Physiol. Chem.,”’ S. 718) ; sarcolactic acid, probably formed 
after death. 

ee f. prakt. Chem., Leipzig, Bd. xxxiii. S. 435. 

6 Arch. f. Physiol., Leipzig, 1887, Suppl., S. 100. 

7 For recent work in ferratin and iron in the liver, and absorption of iron compounds 
as food, see F. Vay, Zischr. f. physiol. Chem., Strassburg, Bd. xx. S. 377; Woltering, 
ibid., 3d. xxi. St 186); Hallieren7- Physiol. Leipzig, 1896, S. 49, 142; Cloétta, 
Arch. f. exper. Path. u. Pharmakol., Leipzig, 1896, Bd. xxxiii. S. 6; Hochhaus and 
Quincke, zbid., S. 152; Quincke, zbid., S. 182. 

8 Meyer and Pernou, Zéschr. f. Biol., Mimmchen, Bd. xxvii. S. 439; Lapicque, Compt. 
rend. Soc. de biol., Paris, tome xli. p. 435. 


ee 


THE SPLERN. 87 


Inorganic constituents of the liver—Oidtmann! found 11 per cent. of 
inorganic material in the liver, of which potassium phosphate, as in 
many other organs, is the most abundant. His numbers per cent. are :— 


Potash 25°17 Phosphoric acid. 43°37 
Soda 14°17 | Sulphuric acid 4 0-9 
Lime 3°62 |  Silicic acid : 0-27 
Magnesia 0-19 Chlorine ; 2 2°5 
Tron, oxide 2°75 Manganese, lead, copper traces. 


F. Kriiger and Lenz? found that the liver cells of the calf contain about 
70 per cent. more calcium than in the ox. During the fcetal period there are 
two maxima and two minima in the amount of calcium, which varies inversely 
with that of iron. In the liver cells of adult men, Kriiger and his assistants ° 
found 2°38 of sulphur, 1:28 of phosphorus, and 0°77 of iron percent. In new- 


~ 


born children the three numbers are respectively 5°56, 1°54, and 0°314. 


The spleen.—The percentage of water in the adult human 
spleen varies from 69-4 to 77-5, the solids, from 31°6 to 22°5, of which 
30-1 to 21-6 consist of organic,and from 1-1 to 0-9 of inorganic, matters.* 

During life the spleen is alkaline. Acidity sets in after death, due 
to the formation of sarcolactic acid? 

The organic constituents of the spleen are proteids and hemoglobin, 
xanthine,® hypoxanthine, uric acid,’ glycogen,’ inosite,® scyllite,"° cerebrin,!! 
cholesterin, lecithin, and jecorin.” Various fatty acids (formic, acetic, 
butyric) described by Scherer ® are, no doubt, derived during the process 
of distillation from the proteids. Leucine and tyrosine, which are 
absent from the fresh organ, are often found as a result of putrefactive 
changes (Hoppe-Seyler). The inorganic constituents are very like those 
found in the liver, except that sodium are more abundant than 
potassium salts.! 

The proteids of the spleen.—Gourlay ® found that the proteids which 
can be extracted from fresh spleen resemble those found in lymphoid 
structures; the most important of these are a cell globulin coagulating 
at 49°-50° C., and a nucleo-proteid coagulating at 57-60° C.  Bottazzi 
confirms these observations in the main. The nucleo-proteid can be pre- 
pared either by Wooldridge’s or the sodium chloride method, and, like that 
obtained from other cellular organs, produces intravascular coagulation. 

1 «Die anorg. Bestandtheile der Leber,” Linnich, 1858. 

2 Zischr. f. Biol., Miinchen, 1895, Bd. xxxi. S. 392. 3 Thid., S. 400. 

4 Oidtmann, Joe. cit. 

> Hirschler, Zischr. f. physiol. Chem., Strassburg, Bd. xi. S. 41. 

§ Scherer, Ann. d. Chem., Leipzig, Bd. evii. S. 314; Stideler, ibid., Bd. exvi. S. 102 ; 
Neubauer, Ztschr. f. anal. Chem., Wiesbaden, Bd. vi. S. 33; Gorup-Besanez, Ann. d. 
Chem., Leipzig, Bd. xeviii. S. 1; Cloétta, ibid., Bd. xcix. S. 289. 

7 Scherer, Gorup-Besanez, Cloétta. 

8 Hoppe-Seyler, ‘‘Med. Chem. Untersuch.,” Bd. iv. S. 495; Abeles, Centralbl. f. d. 
med. Wissensch., Berlin, 1876, No. 5. 

® Cloétta, Scherer. : 

10 Frerichs and Stiideler, MWitth. d. Zurich. natur. Gesellsch., 1855. 

1 Hoppe-Seyler. 22 Baldi, Arch. f. Physiol., Leipzig, Suppl., 1887, S. 100. 

8 Verhandl. d. phys.-med. Gesellsch. zu Wurzburg, Bd. ii. 8. 323. 

M4 Qidtmann gives the following percentages:—Soda, 35-45; phosphoric acid, 18-30 ; 
sulphuric acid, 1°5-2°5; potash, 9-17; oxide of iron, 7-16; silica, 0°2-0°7; lime, 7 ; 
chlorine, 0°5-1°3 ; manganese, copper, lead, traces. For a comparison of the percentage of 
sulphur and phosphorus in the hepatic and splenic cells at different ages, see F. Kruger, 
Zischr. f. Biol., Miinchen, 1895, Bd. xxxi. S. 400. 


9 Journ. Physiol., Cambridge and London, 1894, vol. xvi. p. 23. 
16 Ann. di chim. e di farm., 1895, vol. xxi. 


88 THE CHEMISTRY OF THE TISSUES AND ORGANS. 


Another point in connection with the spleen relates to the question 
whether or not proteoses or peptones are obtainable from it; this is im- 
portant, because Sidney Martin’ has found that the proteoses of diseases 
(diphtheria, tetanus, etc.) accumulate in the spleen. v. Jaksch? states 
that normal spleen contains “ peptone”; but the careful work of Gourlay, 
in which he used Devoto’s ammonium sulphate method and the alcohol 
method failed to detect any. 

Lymphatic glands.—The capsule yields gelatin and mucin lke 
connective tissue structures generally. The reticular tissue yields 
reticulin (see p. 72) and gelatin (see p. 70). The chemistry of the cells 
has been already described (p. 81). 

In a lymphatic gland, about two-thirds are water, the remainder 
solids. The tissue is alkaline during life, and turns acid, due to the 
development of sarcolactic acid, after death.* 

Thymus.—This is also principally lymphoid tissue, and the above 
remarks apply equally well to it. Nothing special is known of the 
chemistry of the concentric corpuscles. The presence of extractives 
like xanthine and hypoxanthine has been noted by Scherer, Gorup- 
Besanez, Frerichs, Stiideler, etc., whose writings have been already 
referred to. Schindler* has estimated the “nuclein or alloxuric bases” 
(see p. 67) obtainable from the thymus of the calf, with the following 
results :— 


Percentage in | Adenine. Hypoxanthine. | Guanine. Xanthine. 
| | 
Fresh tissue. ‘ 0179 0:0023 | 0°0075 0°038 
| | j 
Dry tissue ; | 1°919 0218 | 0°071 0°360 


The high percentage of adenine is noteworthy. Like the other 
organs already described, the reaction, alkaline during life, becomes 
rapidly acid after death. The acid is sarcolactic acid.® 

The thyroid.—This organ is also alkaline during life, but becomes 
acid after death; this is due to sarcolactic acid (Moscatelli). 

Various extractives (fatty acids, xanthine, hypoxanthine, ete.) have 
been found in it by Gorup-Besanez, Scherer, Frerichs, and Stiéideler. 
Inosite has been found by Frinkell® and by Tambach.? The main 
constituents of the thyroid, however, are proteids, and a proteid-like 
substance from the colloid material in the acini. 

Oidtmann found in the adult thyroid, 82:24 water, 17-66 organic and 
0-1 inorganic material per cent. In an infant’s thyroid the numbers 
were 77°21, 22°35, and 0-44 respectively. 

The importance of the chemistry of the thyroid arises from the fact that 
the administration of thyroid extracts has been attended with curative 
results im cases where the thyroid is absent, or no longer forms the 
internal secretion which is believed to be necessary for the nutrition of 
the nervous system. 


1 Goulstonian Lectures, Brit. Med. Journ., London, March 1892. 
? Ztschr. f. physiol. Chem., Strassburg, 1892, Bd. xvi. S. 243. 

3 Hirschler, Zbid., Bd. xi. S. 41. 

4 Tbid., Bd. xiii. S. 438. 

5 Moscatelli, dbid., Bd. xii. S. 416. 

6 Wien. med. Bl., 1895, No. 48 ; 1896, Nos. 13, 14, 15. 

* Pharm. Cenir.-Bl., Leipzig, 1896, Bd. iv. S. 119. 


THE THYROID. 89 


Various attempts have been made to discover the active principle in 
the thyroid which is responsible for its curative properties. Notkin! 
attributes the activity of the gland to its proteid constituents, especially 
to the one called thyreoproteid by Bubnow,? which acts after the 
manner of an enzyme. 

Gourlay* made a thorough investigation of the proteids obtainable 
from the organ. His conclusions were as follows :— 

1. The only proteid that can be obtained in any quantity from the 
thyroid is a nucleo-proteid.4 This may be prepared by either the acetic 
acid or sodium chloride method, and when intravascularly injected 
causes thrombosis. 

2. This is derived, at any rate partly, from the colloid matter in the 
acini; it yields no sugar on treatment with dilute mineral acid, and 
is therefore not a mucin or mucoid. Moreover, the microchemical 
method of Lilienfeld and Monti shows that it contains phosphorus. 
The absence of mucin is confirmed by Frankel and by Hutchison. 

5. Small quantities of albumin are also obtainable. 

A year later Frankel® separated from the gland a crystalline 
material, with the formula C,H,,N,0;, which he called thyreo-antitoxin, 
though the experimental and clinical evidence quoted hardly seem to 
justify the name. 

Roos and Baumann ® have discovered an iodine-containing material, 
which occurs chiefly in combination with the proteid of the organ, but 
partly free. It is remarkable in being insoluble in 10 per cent. hydro- 
chloric acid, a reagent which dissolves all the other substances present. 
It was previously known that the active substance was very stable. 
Thyroid feeding is followed by as good results as injection of thyroid 
extracts ; the active substance therefore resists the action of digestive 
ferments. The substance was named by its discoverers thyro-iodin, or 
todo-thyrin ; it contains 9°3 per cent. of iodine, and 0°56 per cent. of phos- 
phorus. It is not probably a derivation of nuclein, but its constitution is 
not yet known. The amount of iodine per gramme of the organ in human 
adults varies from 0°35 to 0:9. 

Whether this substance is really the important proximate principle in 
thyroid extracts and by inference in the normal internal secretion of the 
organ, must still be left to the future. For, though Roos and Baumann 
state that it acts in every way like thyroid extracts, Gottlieb? has been 
unable to confirm the statement, though possibly, as Auerbach § suggests, 
this is to be attributed to his having used preparations very poor in iodine. 
Weak points in the theory appear to be the absence of the substance 
in the thyroids of children, and in some animals like dogs unless they 
are put on a particular diet (dog biscuits). Small quantities of iodine 
are found also in the thymus. 

1 Wien. med. Wehnschr., 1895, Nos. 19 and 20; Virchow’s Archiv, 1896, Bd. exliv. 
S. 224. The ferment theory was also urged by White and Davies, Brit. Med. Journ., London, 
1892, vol. ii. p. 966. 

2 Zischr. f. physiol. Chem., Strassburg, Bd. viii. S. 1. 

> Journ. Physiol., Cambridge and London, 1894, vol. xvi. p. 23. 

4Morkotun (Vrach, St. Petersburg, 1895, No. 37) gives the composition of this 
nucleo-proteid as—C, 51°46 ; N, 15°56 ; P, 0°32; H, 6°94; S, 1:5; O, 24°22 per cent. 

5 Wien. med. Bl., 1895, No. 48; 1896, Nos, 13, 14, and 15. 

8 Zischr. f. physiol. Chem., Strassburg, Bd. xxi. S. 19, 319, 481; xxii. S. 1, 18. 

” Deutsche med. Wehnschr., Leipzig, Bd. xxii. S. 235, 

8 Centralbl. f. Physiol., Leipzig, 1896, Bd. x. S. 133. For various other references 


to clinical work on this question, see ibid., No. 6. For the influence of iodo-thyrin on 
metabolism, see F. Voit, Ztschr. f. Biol , Miinchen, 1897, Bd. xxxy. S. 116. 


go LAE CHEMISTRVIOL THE TISSUES AND ORGANS. 


This discovery of a compound containing iodine in the animal body 
is a very remarkable one, but is not unique. Almost simultaneously with 
Baumann’s announcement, Drechsel! published a research on the horny 
skeleton of Gorgonia cavolinii. Here he found iodine in organic com- 
bination, and on decomposition the skeleton yielded a crystalline amido- 
acid (iodo-gorgonic acid) of uncertain constitution, and with the formula 
C,H,NIO,. Drechsel has also found iodine in the hair of a syphilitic 
patient, taking iodide of potassium. With reference to the thyroid, he 
suggests the very reasonable hypothesis that this organ produces more 
than one active substance, and that the different substances have 
different actions. He has confirmed the existence both of Baumann’s 
iodo-thyrin and of Frinkel’s thyreo-antitoxin, and has further separ- 
ated out a second crystalline base. Hutchison, however, finds that 
the proteid-free extracts which contain these bases are physiologically 
inactive. He finds that the activity is connected with the 1odine-con- 
taining colloid substance. He distinguishes between the colloid of the 
acini and the nucleo-proteid of the epithelium lining them. The former 
is the active constituent, and is by gastric digestion decomposed into 
two parts. One part is proteid; it contains a little iodine, and has 
feeble physiological powers. The other part is not proteid, and not 
nuclein. It is more active, and contains the greater part of the iodine 
and all the phosphorus of the original colloid. 

The suprarenal body.—In this gland, in addition to proteids and 
the usual extractives and salts (among which potassium phosphate is 
the most abundant), various other substances have been described, such 
as hippuric and taurocholic acid,? benzoic acid, taurine,* and inosite.® 

The chemistry of the suprarenal is of especial interest because of the 
work of Schafer and Oliver® on the action of extracts obtained from 
it. It is now generally beleved that the function of the gland is 
secretory, and that the fatal effects of its removal in animals, or 
disease in man (Addison’s disease), is due to the removal of an internal 
secretion, and not to auto-intoxication from the non-removal of waste 
products.’ The active principle is obtained from extracts of the 
medulla of the healthy gland; it is absent in advanced cases of Addi- 
son’s disease. 

The earlier observers* were inclined to attribute the toxic 
results of suprarenal injections to neurine. This is not so. Neurine 


1 Ztschr. f. Biol., Miinchen, 1896, Bd. xxxili. S. 83; Centralbl. f. Physiol., Leipzig, 
Bd. ix. 8. 704. 

2 Brit. Med. Journ., London, 1896, vol. i. p. ; 1897, vol. i. p. 4; Journ. Physiol., 
Cambridge and London, 1896, vol. Xx. p. 474. 

3 Cloez and Vulpian, Compt. rend. Acad. d. sc., Paris, 1857, tome ii. p. 10; Gaz. méd. 
de Paris, 1858, No. 24. 

4 Seligsohn, Diss., Berlin, 1858; Holm, Journ. f. prakt. Chem., Leipzig, Bd. ec. S. 150. 
Stadelmann could not confirm these statements, Ztschr. f. physiol. Chem., Sneha Bd. 
xvill. Possibly these substances are absorbed from the neighbouring gall bladder and 
kidney. 

5 Kiilz, Sitzwngsb. d. Geselisch. z. Befird. d. ges. Naturw. zw Marburg, 1876, No. 4. 

6 Journ. Physiol., Cambridge and London, 1895, vol. xviii. p. 230. Some speculations 
as to the function of the cortex by Auld will be found, Brit. Med. Jowrn., London, July 
4, 1896; Manasse, Virchow’s Archiv, Bd. exxxy. 8S. 263. 

7 The discovery of heemochromogen in the medulla of the organ by MacMunn (Proc. Roy. 
Soc. London, Bd. xxxix. 8. 248) appeared to favour the removal hypothesis. 

8 Pellacani, Arch. per le sc. med., Torino, 1874, vol. iii. ; Foa, dbid., 1884, vol. viii. ; 
Marino-Zucco, Chem. Centr.-Bl., Leipzig, 1888; Untersuch. x Naturl. d. Mensch. u. d. 
Thier, Bd. xiv.; Arch. ital. de biol., Turin, vol. x. 


THE SUPRARENAL BODY. gt 


can be obtained from the gland, it is true, but the symptoms 
of neurine poisoning are different. The active principle has not 
yet been satisfactorily identified, although its solubilities and many 
of its reactions have been worked out by Moore,! who at first thought 
it identical with a powerfully reducing substance found only in the 
medulla of the gland, and first described by Vulpian.2_ The solubilities 
of this reducing substance are nearly identical with those of the active 
physiological principle. It gives a dark green or blue colour with 
ferric chloride, passing through purple to a dark red on the addition of 
ammonia or sodium carbonate. With chlorine, bromine, or iodine water, 
peroxide of hydrogen, or alkalis in the presence of oxygen, it gives a 
rose-red colour, discharged by sulphide of hydrogen or ammonium sul- 
phide. It is insoluble in alcohol, ether, or benzene; it is soluble in 
water, aleohol plus water, and dilute acids. It dialyses freely through 
vegetable parchment. It is not a proteid, nor a carbohydrate, nor a 
fat, nor is it affected by gastric digestion. 

Manasse,> who investigated the composition of the organ without 
any special reference to the question of its physiological action. or the 
work of Schiifer and his colleagues, states that a reducing substance 
is present, similar in many of its properties to jecorin (see p. 86). It 
is, however, not jecorin; the two substances are alike in some of their 
solubilities, but the material from the suprarenal does not reduce 
Fehling’s solution until after prolonged boiling with sulphuric acid; 
the sugar formed appears to be dextrose. Moore has, however, been un- 
able to obtain from the suprarenal any substance that reduces Fehling’s 
solution. If one, moreover, compares the percentage composition of 
Manasse’s material with jecorin, the difference is seen to be striking, as 
in the following table :— 


! 
SUBSTANCE FROM | 


JECORIN. | SUPRARENALS. 

Drechsel. Baldi. | Manasse. 
Gr 51°32-51°64 4688-46-89 41°43 | 
“u” | 8-11- 8°25 7°81— 8:09 716 
N. | 2°86 4°36— 4°88 0°3 
Ss. | 1°42-1°47 | 2°14— 2°70 1°8 
ie 22 3% DGS POT 4°44 
Na 12, 5°72 RA 
0" 30°10 | 


S. Frankel + has also made an attempt to identify the active substance, 
but with no better success than Moore; according to him, the material 
obtained by Manasse is inactive. Nabarro® has investigated the pro- 
teids of the organ and found them similar to those of other glandular 
structures, namely, cell globulin and nucleo-proteid. They appear to be 
physiologically inactive. In his later work Moore® criticises Frankel’s 

1<¢ Proc. Physiol. Soc.,” London, March 1894 (Journ. Physiol., Cambridge and London, 
vol. xvi. p. i); ibid., March 1895 (Journ. Physiol., Cambridge and London, vol. xvii. p. 
ix.) ; Journ. Physiol., Cambridge and London, vol. xvii. p. 230. 

2 Compt. rend. Acad. d. sc., Paris, tomes xlili. and xly. 

3 Zischr. f. physiol. Chem., Strassburg, 1895, Bd. xx. 8. 478. 

* Wien. ined. Bl., 1896, Nos. 14, 15, and 16. 


5 “Proc. Physiol. Soc.,” London, 1895, Journ. Physiol., Cambridge and London, vol. xvii. 
§ Journ. Physiol., Cambridge and London, 1897, vol. xxi. p. 382. 


92 THE CHEMISTRY OF THE TISSUES:AND ORGANS. 


methods and results. He finds that absolute alcohol, which Frankel 
used for extracting the active substance from the gland, only dissolves 
it in traces; and that the prolonged action of alcohol, especially 
if heat is employed, renders the material physiologically inactive, 
though it still continues to give the colour reactions enumerated 
above. He is inclined to consider the substance to be a derivative 
of piperidine, not of pyrocatechin, as Frankel supposes. Piperidine 
certainly produces a marked rise of blood pressure, like suprarenal 
extract.t 

Pancreas.—This organ is alkaline during life, and rapidly becomes 
acid after death. The solids are like those usually obtamed from cellular 
organs, namely, proteids (for the phospho-gluco-proteid Seyanatas from 
the cland by ‘Hammarsten, see p. 64); extractives (guanine,? xanthine, 
hy poxanthine, leucine? tyrosine, uric acid, lactic acid, mosite), and a 
small proportion of inorganic salts. 

Salivary glands.—The submaxillary gland yields proteids, of which 
the most abundant is a nucleo-proteid ;* the cells also contain mucinogen, 
which passes as mucin into the saliva. The parotid cells contain no 
mucin. A small amount of mucin is, with gelatin, obtainable from the 
investing connective tissue. 

The kidneys.—During life the reaction of renal tissue is alkaline; 
after death it rapidly becomes acid, especially the medulla.’ 

Gottwalt® gives the following table relating to the percentage 
composition of kidney tissue freed from blood :— 


Proteids . ; : : : . 11:185 to 12°217 per cent. 
Gelatin . } ’ : ; . 0996 ,, 13849 a 
Mucin . : ‘ i : . | Traces. 


The following extractives have been obtained by various observers :— 
xanthine, hypoxanthine, creatine, taurine, leucine, cystin, urea, uric acid, 
glycogen, and inosite. 

The kidney also contains a small proportion of inorganic salts (0-1 
to 0°7, Oidtmann). 


The proteids of kidney tissue.—These are very like the proteids of 
other glands, and consist of cell globulin, coagulable by heat at 52° C., 
and a nucleo-proteid. This is far the more abundant ; it coagulates at 
65° C.; it may be prepared by either the acetic acid or sodium chloride 
method. It contains 0°37 per cent. of phosphorus, and produces, like 
other nucleo-proteids, intravascular coagulation. 

The lungs.—The chemical constituents of these organs call for no 
special notice.® 


The testis.—Chemically, the testis is mainly composed of proteids, 


i This was shown independently by Tunnicliffe, Centralbl. f. Physiol., Leipzig, 1897, 
Bd. x. 8. 777. 

* Scherer, Ann. d. Chem., Leipzig, Bd. exii. S. 276. 

Y Virchow, Frerichs, and Stideler, see Hoppe-Seyler, ‘‘ Physiol. Chem.,” S. 260. These 
substances are present in the fresh organ, and are not, as in the spleen, the result of putre- 
faction. 

* Hammarsten, Ztschr. f. physiol. Chem., Strassburg. Bd. xii. S. 163. 

® Halliburton, Journ. Physiol., Cambridge and London, 1892, vol. xiii. p. 806. 
Liebermann ee that the normal reaction of kidney tissue is acid, Arch. f. d. ges. Physiol., 
Bonn, Rd. 1. S. 55. 

6 Ztschr. = ae Chem., Strassburg, Bd. iv. S. 431. 

” Halliburton. loc. cit. 

; he On Lecithin in Lungs and Sputum,” see Zoja, Gazz. med. di Torino, 1894, 
vol. xly. 


bok 


ee 


THE TESTTS. 93 


or substances allied to proteids; of the latter, nuclein and nucleo- 
proteids are the most abundant. 

As in other cases, the fresh gland is alkaline ;! the acidity noted by 
Treskin? was probably the result of post-mortem changes. The extract- 
ives which have been found are leucine and tyrosine (these are probably 
post-mortem products); lecithin, cholesterin, and fat (Treskin); creatine ;# 
inosite ;* adenine, xanthine, hypoxanthine, guanine,*® and other derivat- 
ives of nuclein.® 

The salts present are chiefly chlorides of sodium and potassium 
(Treskin). 

Semen.—The chief chemical constituent of the spermatozoa is nuclein 
(Miescher, see p. 66). Miescher also prepared a base which he called 
protamine, and to which Piccard’ ascribed the formula C,,H.,N,O,. 
Another organic substance, akin to a proteid, and containing 4 per cent. 
of sulphur, was also described by Miescher. 


Kossel§ has examined the protamine from the testis of salmon and stur- 
geons ; he calls it salmine or sturine, according to its origin. He prepared 
from it various crystalline salts, and a new base, C,H,N,0O,, he terms 
histidine. ° 

Among other substances he prepared from fishes’ spermatozoa, was thymin, 
the substance he had previously got from the nucleic acid of the thymus 
(see p. 66). 


Lecithin, next to nuclein and proteids, is the chief organic substance 
in spermatozoa.!? Cholesterin and fat are also fairly abundant. Miescher 
gives the following percentage for the salmon’s spermatozoa :— 


Nuclein . . 46°68 per cent. | Lecithin . . 7:47 per cent. 
Protamine 5 PAT ae | Cholesterin 2 ae 
Proteids . elOiaae 7 | Fat . : ee 5, 


Miescher continued to work at this subject (salmon’s spermatozoa) 
throughout his life. He, however, never published much beyond his 
early papers. After his death, Schmiedeberg published an article! 
compiled from his numerous notes. This paper relates to the quantitat- 
ive composition of the spermatozoa, and gives analyses of the principal 
substances obtained from them, especially nuclein and protamine. He 
considers these are in chemical union, thus: 


ji Cy H5N401(P05). 1+ CigH NO, 


(nucleic acid) (protamine) 


The heads of the spermatozoa contain 60°73 per cent. of nucleic acid 
and 19°78 per cent. of protamine. The tails (which are soluble in 


1 Sertoli, Gazz. med.-vet., Milano, 1872, Anno ii. 

2 Arch. f. d. ges. Physiol., Bonn, Bd. vy. S. 122. 

* Schottin, see Hoppe-Seyler, ‘‘ Physiol. Chem.,” S. 773. 

*Schottin, Kiilz, Sitzwngsb. d. Geselisch. z. Befird. d. ges. Naturw. zu Marburg, 1876, 
No. 4. 
° Schindler, Ztschr. f. physiol. Chem., Stvassburg, Bd. xiii. S. 438. 
6 Kossel, ibid., 1896, Bd. xxii. S. 172, 188; Hedin, zbid., S. 191. 
7 Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. vii. S. 1714. 
8 Loc. cit. 
® Hedin (Joe. cit.) believes histidine is identical with a base he had previously obtained 
his work on the decomposition products of proteids. 
10 Diaconow ; see Hoppe-Seyler’s ‘‘ Med. Chem. Untersuch.,” Bd. ii. S. 221 ; iii. S. 405. 
" Arch. f. exper. Path. u. Pharmakol., Leipzig, 1896, Bd. xxxvii. S. 100. 


i 


=) 


94 THE CHEMISTRY OF THE TISSUES AND ORGANS. 


saline solutions) contain, proteid, 41:9; lecithin, 31°75; fat and choles- 
terin, 26°27 per cent. In young spermatozoa some interest attaches 
to the presence of a proteose which is regarded as the mother 
substance of protamine. Proteose and protamine both give the biuret 
reaction. 

Charcot’s erystals.—These can be obtained from semen on evaporation.! 
They are frequently found in sputum, in the blood, and in other situa- 
tions, in leucocythzemia. Schreiner? considered that they consist of the 
phosphate of a base he called spermine, C,H,N. Ladenburg and Abel ? 


Fie, 12.—Charcot’s crystals. 


thought they were identical with ethylenimine, which can be prepared 
artificially from ethylenediamine-hydrochloride. This identity, however, 
is denied by Majert and A. Schmidt* and by Poehl.® Poehl gives the 
formula C,H,,N, to the base. He states that it is a normal constituent of 
the testis, ovary, and blood, and that, used as a drug, it has a tonic effect. 
Ovary.—The connective tissue element is large, and yields chiefly 

gelatin and mucin. Proteids and nuclein are derived from the ova and 

1 Bottger, Virchow's Archiv, Bd. xxxil. S. 525, 

2 Ann. d. Chem., Leipzig, Bd. cxciv. S. 68. 

3 Ber. d, deutsch. chem. Gesellsch., Berlin, Bd. xxi. 8. 758. 


4 Compt. rend. Acad. d. sc., Paris, tome cxv. 
5 Berl. klin. Wehnschr., 18938, No. 36. 


MUSCLE. 95 


other cells present. The corpora lutea are coloured by lutein. This is a 
lipochrome (see p. 20). Thudichum?! was the first to point out that it 
is distinct from hematoidin, which is also generally present. 

The constituents of eggs are described with the various proteids, 
ete., of which they are made up. 


MUSCLE. 


Skeletal muscle.—A muscle contains, besides the muscular fibres, 
supporting connective tissue with fat. Each fibre consists of two parts, 
the sheath or sarcolemma, and the contractile substance which it 
encloses. The sarcolemma resembles elastin very closely in its 
solubilities.” 

The contractile substance is of soft consistency, and contains a large 
percentage of proteids, and smaller quantities of various extractives and 
salts. By the use of a press a juice can be squeezed out of perfectly 
fresh muscles, which is called the muscle plasma. Like blood plasma, 
this coagulates, and the proteid clot is called myosin; this occurring 
within the body after death is the cause of rigor mortis. 

Living muscle is alkaline; but after extreme activity, and after 
death, the reaction becomes acid: this is due in part to the development 
of sarcolactic acid. 

The percentage of water in muscle varies in different animals: ?— 


Man . 72to 74 percent. | Birds . 70 to 76 per cent. 
Gx: eel. 7 | aaa (Ads ee 
Pig.  &8 = _ Fishes VS Seat 3 7 ae 
Cat... ae hs a | Crab eee) a 
Boxe. 74 i" febecied 79,80)". 


In young animals, and during inanition, the percentage of water is 
greater. 


Human muscle has the following average percentage composition :— 


Water . ‘ : : . : ; . 73°5 per cent. 
Solids. i 26°5 


Proteids, including sarcolemma, proteids of con- 


bP) 


nective tissue, vessels, and pigments 18-07), 
Gelatin . je ae 
Fat : ri} me 
Extractives (creatine, lactic acid, glycogen, etc.) 0 ee ee 
Inorganic salts ; 3°12 


2 


This may be compared with the muscle of a molluse (Pecten) : 4— 


Water. ; 4 : . 79°60 to 80°25 per cent. 
Solids. : ‘ : 5 Pena 0, Wg bil. 
Proteids . : : : , ertihbe - 2 Omar” 2 
Glycogen. : : : : ees an EOD! gue ys 
Glycocine ; z ; ; eT Liem Oaasely Gs 
Ethereal extractives . ; F SN HOSS) 3s, VOI J: 
Inorganic salts . : , call a ana te ae 


1 Centralbl. f. d. med. Wissensch., Berlin, 1869, Bd. vii. S. 1. 
2 Ewald, Zischr. f. Biol., Miinchen, Bd. xxvi. 8. 1. 
3 Schlossberger, “Chem. der Gewebe, ” Leipzig and Heidelberg, 1856, S. 169; Gorup- 
Besanez, ‘‘ Lehrbuch,” 1878, S. 676; Hoppe- Seyler, ‘‘ Physiol. Chem. 28 636. 
4 Chittenden, Ann. d. Chem., Leipzig, Bd. elxxviii. S. 266. 


96 THE CHEMISTRY OF THE TISSUES AND ORGANS 


Muscle considered as meat is the most concentrated and most easily 
assunilable of the animal nitrogenous foods. It forms our chief source 
of nitrogen. In 100 parts of nitrogen from beef, 77-4 come from proteid 
insoluble in water, 10°08 from soluble proteid, and 12°52 from extract- 
ives! In addition to the proteids, extractives, and salts contained in 
muscle, the flesh used as food contains a certain variable percentage of 
fat, even though all visible adipose tissue is cleaned off. In estimating 
the amount of fat, Dormeyer? recommends that the meat should be 
subjected to artificial digestion before extraction with ether; flesh then 
yields an additional 0°75 per cent. of fat. 


The following table® gives the chief substances in some of the principal 
meats used as food :— 


Constituents. | Ox. Calf. Pig. Horse. Fowl. Pike. 
Watery: é : : : 76°7 75°6 72°6 74:3 70°8 79°3 
Solids. > é : : 23°3 24°4 274 Da 29°2 20°7 
Proteids and gelatin : . | 200 19°4 19°9 21°6 22°7 18°3 
Fat : : : ° : 1°5 2°9 6°2 2°5 4-1 07 
Carbohydrate . F ; ’ 0°6 Os8h We WOs6 0°6 ilies 0:9 
Salts inen tad Weak t | eller) | as | Lt joo || ai 


The flesh of young animals is richer in gelatin than that of old ones; 
thus 1000 parts of beef yield 6, of veal 50, parts of gelatin (Liebig). 


Meat contains four times the amount of proteid present in an equal 
weight of milk. 

The process of cooking meat (after it has been kept to allow rigor 
mortis to pass off) renders the investing connective tissues looser, 
separates the muscular fibres, and destroys parasitic growths. The 
muscular fibres themselves, especially if boiled, are rendered more 
difficult of digestion. 

The muscle plasma and the muscle serwm.—Kiihne* was the first to 
obtain muscle plasma; he used frogs’ muscle. The fresh blood-free 
muscle is frozen and subjected to strong pressure, the expressed fluid 
(muscle plasma) is filtered ; it is found to be syrupy in consistence, and 
faintly alkaline. As the temperature of the plasma rises to that of the 
air, it clots, and the myosin, so formed, contracts to a slight extent, 
squeezing out muscle serum. Kiihne found this latter fluid to contain— 

(1) A proteid coagulating at 45° C.; (2) an alkali albumin ;° (3) a 
small quantity of albumin; (4) extractives and salts. 

A good many years later, I was successful in repeating these ex- 
periments with mammalian muscle,’ and showed, moreover, that not only 

1 Salkowski, Centralbl. f. d. med. Wissensch., Berlin, 1894. 

2 Arch. f. d. ges. Physiol., Bonn, 1895, Bd. lxi. S. 341 ; 1896, Bd. Ixv. S. 90; Schulze, 
ibid., S. 299; 1897, Bd. Ixxii. S. 145. 

3 Munk’s ‘‘ Physiologie,” Aufl. 4, 8. 280. 

4 Tehrbuch d. physiol. Chem.,” S. 272; ‘‘Untersuch. ii. das Protoplasma,” Leipzig, 


1864. 
5 The natural alkali albumins described by older workers are no doubt all globulins. 
6 Halliburton, Journ. Physiol., Cambridge and London, vol. viii. pp, 133-202. 


SKELETAL MUSCLE. 97 


does cold prevent the coagulation of muscle plasma, but, as in the case of 
blood plasma, admixture with solutions of neutral salts has the same 
effect. Addition of water to the salted muscle plasma brings about 
coagulation (an acid reaction making its appearance simulté meously), 
especially at 40° C., and still more rapidly if solution of “myosin 
ferment” is added. The myosin ferment was prepared from muscle 
in the same way as fibrin ferment from blood serum. 

Saline extracts of muscle which has undergone rigor mortis, resemble 
salted muscle plasma very closely ; after dilution they undergo coagula- 
tion; this may be a re-coagulation of the redissoly ed myosin, for the 
acidity of the saline extract is increased by re- -coagulation. Some 
observers, however, regard this phenomenon not as a true re-coagulation, 
but as a simple precipitation of the myosin by dilution with w ater. 

Myosin may be most readily extracted from muscle by means of 
ammonium chloride solution, and may be precipitated in a gelatinous 
form by dialysing away the salt.t Elementary analysis ? ees the 
following results :—C, 52°79; H, 7:12; N, 16°86; 58, 1 26; Oo22 oF 

Recent research has shown that calcium salts are essential for the 
effective coagulation of milk and blood. The facts are not so positive 
in the case of muscle, but there is some evidence pointing to the 
existence of an analogy in the three cases.” 

By fractional heat coagulation, and by their varying solubilities in 
different salts, I was able to separate four different proteids in the 
muscle plasma. 

(1) A globulin precipitable by heat at 47° C. This is analogous to 
the cell globulin found in most protoplasmic structures. It is termed 
musculin by Hammarsten. I gave it the name paramyosinogen. 

(2) A globulin precipitated by heat at 56° C. This is the proteid 
which is especially acted on by the myosin ferment, and is converted 
into myosin. I termed it myosinogen: both it and paramyosinogen 
contribute to the muscle clot. 

(3) A third globulin precipitated at 63° C. (myoglobulin) is con- 
tained in the muscle serum. 

(4) Small quantities of an albumin (myoalbwmin), similar in its 
properties to serum albumin, are also present. 

In addition to this, in the case of red muscles, there is hemoglobin; 
and if the muscle has been kept warm, and acidity developed, small 
quantities of proteoses and peptone, which are formed by a process of 
self-digestion. Briicke showed, many years ago, that muscle contains 
small quantities of pepsin, doubtless absorbed from the gastric mucous 
membrane; this becomes active on the onset of acidity. The action of 
such a ferment within the body will perhaps explain the phenomenon 
called the disappearance of rigor mortis; it is es to suppose 
that this is always due to putrefactive organisms,* since rigor often dis- 
appears before putrefaction sets in. Perfectly fresh muscle contains no 
proteose or peptone.® 

Whitfield also investigated the question whether myosin or its precursors are 


1 Kiihne and Chittenden, Zéschr. f. Biol., Miinchen, Bd. xxv. S. 358. 

2 Chittenden, ibid. See also Stud. Lab. Physiol. Chem., New Haven, 1889, vol. iii. 
p. 116. 

3 Locke, Journ. Physiol., Cambridge and London, vol. xvii. p. 293 ; other references will 
be found in this paper. 

+ Cossar Ewart, Proc. Physiol. Soc., London, 1887, p. xxv. 

° Whitfield, Journ. Physiol., Cambridge and London, 1894, vol. xvi. p. 487. 


VOL, 1.—7 


98 THE CHEMISTRY OF THE TISSUES AND ORGANS. 


of the nature of nucleo-proteids. He found that they are not. He was indeed 
able to obtain no nucleo-proteid at all from muscle. Pekelharing! has taken 
up the latter question, and by an improved method discovered that muscular 
tissue does contain a small amount of nucleo-proteid. He points out that on 
gastric digestion small quantities of nuclein are soluble, if the amount of 
hydrochloric acid preseut exceeds 071 per cent. Whitfield used water as an ex- 
tracting agent for any possible nucleo-proteid. _Pekelharing points out that the 
water will soon become acid from sarcolactic acid, and uses dilute (0°15 per cent.) 
sodium carbonate solution instead. From such an extract the nucleo-proteid 
can be precipitated by acetic acid. From 543 grms. of flesh he obtained 2 grms. 
of nucleo-proteid. This substance produces intravascular clotting, and contains 
0:7 of phosphorus. The nuclein split off from it contains 3°5 per cent. of 
phosphorus, and on decomposition yields alloxuric bases, especially xanthine 
and guanine. Hypoxanthine and adenine were not found. Kossel? also failed 
to get adenine from muscle. 


An important research on muscle plasma and its proteids has lately 
been published by v. Fiirth.? He obtained the plasma from blood-free 
muscles by extracting them with physiological saline solution. This 
extract coagulates spontaneously, and the clotted proteid formed he calls 
myogen fibrin or myosin fibrin. The proteids in the muscle plasma he re- 
duces to three, namely, paramyosinogen, 17 to 22 per cent. of the total pro- 
teid ; myosinogen or myogen, 77 to 83 per cent., and traces of an albumin.+* 

My work is confirmed in its main point, namely, that there are two 
proteids in the muscle plasma, paramyosinogen and myosinogen, which 
enter into the formation of the muscle clot; the action of a specific 
ferment to bring about this change was not specially investigated. The 
principal new fact made out is, that paramyosinogen passes into the 
condition of myosin fibrin directly ; whilst i the passage of myosinogen 
into the state of myogen fibrin, there is an intermediate soluble stage 
coagulable by heat, at the remarkably low temperature of 40° C.° 


Paramyosinogen is described as a typical globulin, and is regarded as 
identical with Kiihne’s myosin which he obtained by dropping muscle plasma 
into water. Myosinogen is described as differing from a globulin in some 
particulars, and is spoken of as a proteid swé generis. Myoglobulin is not 
regarded as a separate proteid, but as part of the myosinogen which has 
escaped coagulation. The phenomenon regarded by Chittenden and myself as 
re-coagulation of myosin is considered to be a simple re-precipitation of globulin. 
Whitfield’s work on the absence of peptones and proteoses is confirmed. 

The muscle plasma from fishes’ and crabs’ muscle contains another proteid, 
called myo-proteid. It gives the usual proteid reactions, and is readily digested 
by gastric juice; though precipitated by a removal of the salts by dialysis, it 
is not coagulable by heat. It is precipitable by acetic acid, but is neither a 
mucin nor a nucleo-proteid. 

In his second paper, v. Furth treats of (1) the properties (solubilities, 

1 Ztschr. f. physiol. Chem., Strassburg, 1896, Bd. xxii. S. 245. 

2 Ibid., 1886, Bd. x. S. 248. 

3 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1895, Bd. xxxvi. S. 231; also ¢bid., 
1896, Bd. xxxvii. S. 389. 

4J. H. Milroy (Arch. f. Hyg., Miinchen u. Leipzig,1896, Bd. xxv. S. 154) has also made 
quantitative estimations of the various muscle proteids coagulable at different temperatures. 

° If the reader refers to my memoir on ‘‘ Muscle Plasma,” he will find, on p. 186, that I 
accidentally noted this fact, though I failed to appreciate its meaning. In frogs’ muscle 
plasma there is a considerable amount of this soluble myogen fibrin in a “ preformed” 
condition (v. Fiirth). The separation of the muscle proteids by fractional heat coagulation 
fits in exactly with Brodie and Richardson’s work on heat rigor; as the temperature of a 


muscle is raised, successive shortenings occur at the coagulation temperature of each 
proteid (Proc. Roy. Soc. London, 1897, vol. 1xi. p. 77). 


SKELETAL MUSCLE. 99 


effect of numerous reagents, etc.) of myosinogen and paramyosinogen; (2) the 
influence of blood serum in hindering the coagulation of the muscle plasma ; 
and (3) the action of various chemical substances on living muscle. 

Involuntary muscle—Our chemical knowledge of involuntary muscle 
is of afragmentary nature. Like voluntary muscle, the heart becomes 
rapidly rigid after death, and simultaneously acid, from the formation of 
sarcolactic acid. Both paramyosinogen and myosinogen are present in 
the muscle cells of the heart, and myosin is the result of coagulation. 
In the stomach and uterus, rigor has been observed, but in other forms 
of plain muscle it is difficult to recognise. A proteid coagulating at 
56° C., has been obtained from all kinds of unstriped muscle. In a 
muscular tumour of the uterus, Kossel? found the one coagulating at 
45° C. (paramyosinogen) to be absent. 

The reaction of unstriped muscle is normally alkaline. Lehmann # 
found small quantities of lactic acid in the muscular substance of the 
stomach after death. There is, however, no marked change in the 
reaction after death, as in striated muscle. Du Bois-Reymond® observed 
in the stomach and intestines of birds that after death the muscular 
walls were still alkaline. 

Myohematin—Though hemoglobin is the pigment of the red 
muscles, MacMunn® considers that the specific pigment of ordinary 
muscle is myohematin, one of the most widely distributed of the colour- 
ing matters which he has described under the name /istohematins. The 
histohematins have only been observed by the spectroscope; they have 
not been separated out by chemical processes. They often occur in 
animals that possess no hemoglobin. As they undergo changes in their 
absorption bands, by oxygenation and reduction, it is believed that they 
are respiratory in function. The spectrum of these substances is some- 
what like that of heemochromogen; and Levy, working under Hoppe- 
Seyler,’ has gone so far as to say that myohzematin is hemochromogen 
produced by the methods used to render the muscle transparent. The 
resemblance is not absolute, but is specially close in what MacMunn calls 
modified myohematin. This is produced by artificial gastric digestion ; 
or it can be obtained in the following way:—The muscle is chopped finely 
and covered with ether for some days. A yellow lipochrome derived from 
the fat between the muscular fibres® passes into solution, and below this 
floats a red juice, which on filtration gives the spectrum in question. 

Until myohematin and the other histohematins are examined 
by methods other than spectroscopic, it is impossible to pronounce 
positively on the point of dispute between MacMunn and Levy. The 
fact that in the last experiment described, the muscles, even if they are 
full of blood, yield no longer any hemoglobin, poimts to hemoglobin 
as the source of the myohematin; whether this substance can be pro- 
duced in the muscles intra vitam must be left to the future to decide.® 

The extractives of muscle.—These are—(a) Nitrogenous, namely, 


1 Boruttau, Ztschr. f. physiol. Chem., Strassburg, Bd. xviii. S. 513. 

2 Quoted by Hoppe-Seyler, ‘‘ Physiol. Chem.,” S. 669. 

* Bernstein (Kiihne’s ‘‘ Lehrbuch,” S. 332) found the actively contracting muscles of 
Anodon acid. 4 << Lehrbuch,” Bd. iii. S. 73. 

° Monatsh. d. k. preuss. Akad. d. Wissensch. zu Berlin, 1859, 8. 312. 

§ Phil. Trans., London, 1886 ; Journ. Physiol., Cambridge and London, vol. vii. 

* Ztschr. f. physiol. Chem. , Strassburg, Bd. xiii. MacMunn’s replyis inthe same vol., S. 497. 

8 Halliburton, Journ. Physiol., Cambridge and London, vol. vii. p. 325. 

* K. Morner (Nord. med. Ark., Stockholm, Festband, 1897) states that muscle pigment is 
hemoglobin which spectroscopically shows slight differences from that obtained from blood. 


too THE CHEMISTRY OF THE TISSUES AND ORGANS. 


creatine, creatinine, xanthine, hypoxanthine, carnine, carnic acid, uric 
acid, urea, taurine, and inosinic acid. (b) Non-nitrogenous, namely, fats, 
glycogen, inosite, dextrose, and lactic acids. 

Creatine and creatinine. —Creatine can be crystallised out by 
evaporating aqueous extracts 
of meat from which proteids 
and salts have been previously 
removed; on heating it with 
mineral acids it is converted 
into creatinine. The relation- 
ship of these two substances 
is shown by the following 
equation :— 

C,H,N,O,—H,O = C,H,N,O 
(creatine) (creatinine) 
According to Voit, the 

quantity of creatine in the 
voluntary muscles varies from 
0-2 to 03 per cent. 7 ime 
increases during — starvation.? 
Involuntary (cardiac and plain) contains less than voluntary muscle.* 

The compound with zine chloride which creatinine forms (Fig. 15) has 
been generally used for isolating it from urine, and other places where it 
occurs. My own experience with 
this method has shown that for 
quantitative purposes it is most 
uncertain; and this no doubt ac- 
counts for the different results 
obtained by different observers. 
Thus Neubauer denies the exist- 
ence of creatine in muscle 
altogether; Voit, Sarokin,* and 
Monari® say that it increases 
during muscular activity, while 
Nawrocki® states that it does 
not. Much more certain results 
are obtained by the use of G. 5. 
Johnson’s method, in which he 
precipitates the creatinine as a 
compound of mercury.’ This 
method, which has received the 
powerful recommendation of Hoppe-Seyler$ may be used to identify 
creatinine when it is present in very small quantities, as in the blood.® 
The microscopic appearance of the precipitate is shown in Fig. 16. By 


Fic. 13.—Creatine crystals. —A fter Kiihne. 


Fic. 14,—Creatinine crystals.—After Kiihne. 


1 Ztschr. f. Biol., Miinchen, Bd. iv. S. 77. 

* Demant, Zischr. f. physiol. Chem., Strassburg, Bd. iii. S. 387. 

3 Voit, Joc. cit. ; Lehmann, ‘‘ Lehrbuch,” Bd. iii. S. 73. 

4 Virchow’s Archiv, Bd. xxvii. > Gazz. chim. ital., vol. xvii. p. 367. 

§ Centralbl. f. d. med. Wissensch., Berlin, 1865, S. 417. 

7 Proc. Roy. Soc. London, vol. xlii. p. 365; xlii. p. 493; 1 p. 28. Johnson 
here points out that there are several isomeric varieties of creatinine, differing in reducing 
power, ete. In his process he is careful to employ no heat; otherwise the creatinine is 
transformed into a non-reducing variety, or even may be changed into creatine. 

8 “Handbuch. d. physiol. chem. Analyse,” 1893, 7th edition, S. 142. 

* Colls, Journ. Physiol., Cambridge and London, 1896, vol. xx. p. 107. 


THE EXTRACTIVES OF MUSCLE. 101 


this means Johnson showed that creatinine (a different creatinine from 
urinary creatinine) is more abundant in muscle than creatine, which 
is usually almost entirely absent. This unexpected result has been 
confirmed by Kemmerich.t Creatinine is readily changed into creatine 
by the action of putrefactive micro-organisms. 

Xanthocreatinine (C,H,,N,O), erusocreatinine (C,H.N,O), amphierea- 
tine (C,H,,N;O,), and pseudoranthine (CjH;N;O) are leucomaines stated 
by Gautier? to be present in small quantities. 

Xanthine, hypoxanthine, and urve acid are found in small quantities 
only; the numbers given are as follows :—xanthine, 0:0026 per cent.;? 
hypoxanthine, 0:022-0-026;4 uric acid, traces.6 Uric acid is more 
abundant in the muscles of reptiles (alligators). The crystalline forms 
of some of the compounds of xanthine 
and hypoxanthine are given in Fig. 17. 

Carnine is a erystalline base 
(C,H,N,O,+H,0), originally found by 
Weidel® in large quantities (1 per 
cent.) in American meat extracts, but 
since found in the flesh of many 
animals.’? It is probably closely re- 
lated to the members of the uric acid 
group just mentioned. 

Urea.—lt is generally stated that 
muscle contains little or no urea. 
This statement is chiefly due to the 
fact that it was until recently a R ae 
memeeaeror edificulty to. -weparater ane ae chloride crystals- 
urea, when only present in small . 
quantities, from other nitrogenous bases. In some animals, however, 
the muscular tissue contains a fairly large amount of urea. This is 
the case with the muscles of arthropods.$ Stiideler and Frerichs® 
were the first to discover that the organs, including the muscles, 
of Selachian fishes are rich in urea. This was confirmed in the case 
of Selachian embryos by Krukenberg, and more recently in the 
adult animals by Schroder4 In two varieties of dog-fish, the 
mean percentage of urea in the blood was 2°61, in muscle 1°95, and 
in liver 1:56. Schroeder explains this by the fact that the kidneys are 
sluggish in these animals. By a new method, Schéndorff” has been 
able to satisfactorily establish the existence of a small quantity of 
urea in the muscles of mammals; Kaufmann? gives the percentage 


1 Kemmerich, Ztschr. f. physiol. Chem., Strassburg, 1894, Bd. xviii. S. 409. 

2 Jahresb. it. d. Fortschr. d. Thier-Chem., Wiesbaden, Bd. xxii. S. 335. 

® Scherer, Ann. d. Chem., Leipzig, Bd. evii. S. 314. 

+ Neubauer, Ztschr. f. anal. Chem., Wiesbaden, Bd. vi. S. 33. 

® Meissner, Zischr. f. rat. Med., Leipzig, Bd. xxxi. p. 144. 

6 Ann. d. Chem., Leipzig, Bd. clviii. S. 353. 

7 Krukenberg and Wagner, Sitzungsb. d. phys.-med. Gesellsch. zu Wiirzburg, 1883, No. 4. 
See also Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, Bd. xi. S. 340. 

8 Krukenberg, Untersuch. a. d. physiol. Inst. d. Univ. Heidelberg, 1881, Bd. iv. S. 33; 
*‘ Vergleich. physiol. Vortrige,” 1886, S. 313. 

® Journ. f. prakt. Chem., Leipzig, 1858, Bd. xxiii. S. 48 ; ibid., Bd. lxxvi. S. 58. 

10 «* Vergleich. physiol. Vortrage,” 1886, S. 314. 

U Ztschr. f. physiol. Chem., Strassburg, 1890, Bd. xiv. 8. 576; Krukenberg, Centralbl. 
jf. d. med. Wissensch.. Berlin, 1887, No. 25. 

2 Arch. f.d. ges. Physiol. , Bonn, 1895, Bd.1xii.S.332. Forthe methodemployed, see 7bid.,S.1. 

3B Arch. de physiol. norm. et path., Paris, Sér. 5, tome vi. 


102 THE CHEMISTRY OF EFHE TISSUES AND ORGANG. 


as 0°027 to 0°07. On the other hand, it must be stated that such 
an experienced chemist as Nencki! is still unable to discover any 
urea in muscle. 

Taurine is found in the muscles of horses, fishes, and molluses. In 
fishes Limpricht? found 1:06 per cent. 

Glycocine is found to the extent of 0°39 to 0°71 per cent. in the non- 
striated muscles of molluses.* 

Protie acid is an acid of doubtful nature, described by Limpricht in 
fishes’ muscles. 

Inosinic acid (C,H,,N,0,,) was first described by Liebig, and 


Frc. 16.—Spherical compound of mercury and creatine.— 
After G. S. Johnson. 


estimated (0:005 to 0-02 per cent.) by Creite4 According to Frankel, 
it is closely related to carnic acid, to be immediately described. 

Lecithin and its decomposition products are present in small 
quantities, and are probably ‘derived from the nerves supplying the 
muscle. Small quantities of cholesterin are found as well. 

Carnie acid (Fleischséure) is the name given by Siegfried? to a con- 
stituent of muscle, the discovery of which is of great importance. He 
first prepared it from muscle extracts by means of ferric chloride; the 
compound so obtained is called carniferrin; this contains phosphorus as 


' Nencki and Kowaski, Arch. f. exper. Path. uv. Pharmakol., Leipzig, 1895, Bd. xxxvi. 
S. 395. 

2 Ann. d. Chem., Leipzig, Bd. exxvii. S. 185; exxxiii. 8. 300. 

® Chittenden, ibid., Bd. elxxviii. S. 266. 

4 Ztschr. f. rat. Med., Leipzig, Bd. xxxvi. S. 195. 

» ** Zur Kenntniss der Zerfallproducte des Eiweisses,” Wien, 1896. 

6 Hoppe-Seyler, ‘‘ Physiol. Chem.,” S. 647. 

” Ber. d. deutsch. chem. Geseilsch., Berlin, 1894, Bd. xxvii. S. 2762; Ztschr. f. physiol. 
Chem., Strassburg, Bd. xxi. S. 360. 


THE EXTRACTIVES OF MUSCLE. 103 


well as iron. By means of baryta water, carnic acid (C,,H,,;N,0;) was 
separated out from it. In muscle, this acid is combined with phosphorus 
as phospho-carnic acid. Carnie acid itself is identical with antipeptone. 
This discovery itself shows that our views concerning the hemi- and 
anti-products of digestive proteolysis will need revision. Carnic acid 
is a comparatively “simple substance, of low molecular weight, and of 


5 
acid reaction. It is free from sulphur, and gives most of the proteid 


Pome 


=e a en —— 


Fic. 17.—Compounds of xanthine and hypoxanthine, by means of which these substances 
may be isolated and identified.—After Kiihne. 


a. Hypoxanthine silver nitrate, C;H,N,0.AgNO,. 
6. Hypoxanthine nitrate, C. H. NEO} HNO,. 
c. Hypoxanthine hydrochloride, é. lab dy] yO; HCl. 
* Xanthine silver nitrate, C,H,N Ou “AgNO,. 
Xanthine nitrate, C, HH, 'N, Oss HNO,. 
Xanthine hy drochloride, é. H ANOS, HCl. 


tests; it does not give Millon’s reaction. This discovery will no doubt 
form an important clue in the problem of proteid constitution. This 
announcement of Siegfried’s has been fully confirmed by Balke,! 
who has prepared many compounds and derivatives (oxycarnic acid, 
C.5H,,N,O,,;; oxylic acid, C,,H,,.N,O,; and various crystalline metallic 
salts of these acids), and has devised a method for its estimation.2 It 


1 Ztschr. f. physiol. Chem., Strassburg, 1896, Bd. xxii. S. 248, 
2 Balke and Ide, zbid., Bd. xxi. S. 380. 


104 ZLHE CHEMISTRY OF THE TISSUES. AND ORGANS. 


has been further confirmed by Frinkel,t who finds that pure ampho- 
peptone is also sulphur-free. 

Phosphocarnic acid has a complicated molecule; it yields on 
decomposition carnic acid, carbonic anhydride, succinic acid, sarcolactic 
acid, and a strongly reducing carbohydrate. Siegfried compares it to 
nuclein; but nucleins yield proteid on decomposition; phosphocarnic 
acid yields carnic acid (antipeptone) instead; he suggests the term 
nucleon for it. The percentage of this substance in human muscle is 
0-1-0°2.. In new-born children the muscles contain less (0 to 0:06 per 
cent.” 

A phosphocarnic acid is also found in milk, but differs from that in 
muscle by yielding fermentation lactic acid instead of sarcolactic acid 
on decomposition.® 

Kriiger * has found that on hydrolysis and simultaneous oxidation by 
means of ferric chloride, phosphocarnic acid gives off carbonic anhydride ; 
no other substance in muscle extracts does this. He therefore looks 
upon it as the material in muscle which during muscular activity gives 
off carbonic anhydride without using up oxygen. This is a conclusion 
that requires serious consideration and renewed research before it can 
be accepted, but it is another indication of the importance of Siegfried’s 
work. 

We now pass to the non-nitrogenous extractives :— 

Glycogen.—This substance may be extracted from muscle by hot 
water®; or by dilute potash®; the latter reagent effects a much more 
thorough extraction. Cramer using Kiilz’s method, found that different 
groups of muscles contain varying amounts of elycogen, but that corre- 
sponding muscles of the two sides of the body contain the same amount. 
In the heart, glycogen is unequally distributed in the different regions 


(Cramer). The average percentage of glycogen in fresh heart muscle 


is, however, about the same as in voluntary muscle, though it dis- 
appears after death (being converted into sugar as in the liver) more 
rapidly than in skeletal muscle.S Glycogen also occurs in other 
involuntary muscles.® 

The glycogen in muscle during life varies in quantity. The following 
are the principal causes of variation :— 

1. Starvation.—The muscle glycogen disappears during inanition, but 
much more slowly than the hepatic glycogen.?  Luchsinger? stated 
that the glycogen of the heart muscle disappears still less quickly, but 
Aldehoff (using Kiilz’s method) could not confirm this. 


1 Loc. cit. 

2M. Miiller, Zschr. f. physiol. Chem., Strassburg, 1897, Bd. xxii. S. 561. 

* K. Wittmaack (zbid., S. 567) gives the perce entage of nucleon in human milk as 07124 ; 
in cows’ milk, 0°056, and in goats’ "milk, 0-11. Blumenthal (Virchow’s Archiv, Bd. exlvi. 
8. 65) gives the pere entage in cows’ milk as 0-05. 

4 Zischr. F. physiol. Chem. , Strassburg, 1896, Bd. xxii. S. 95. 

5 Briicke, Sitz ungsb. d. k. Akad. d. VV 7issensch. , Wien, 1871, Bd. lxiii. Abth. 2, 8. 214; 
Nasse, Arch. f. d. ges. Physiol., Bonn, Bad. ii. S. 97. 

6 Abeles, Med. Jahrb., Wien, 1877, S. 551; Kiilz, Ztschr. f. Biol., Miinchen, Bd. xxii. 
S. 161. See also Schmelz, zbid., Bd. xxy. S. 180. 

7 Ibid., Bd. xxiv. S. 67. 

8 Boruttau, Ztschr. f. physiol. Chem., Strassburg, Bd. xviii. S. 518. 

*In the stomach, Briicke, Joc. cit. ; in the plain muscles of gastropods, Chittenden, 
Ann. d. Chem., Leipzig, Bd. clxxviii. S. 266 ; Bizio, Atti. r. Ist. Veneto di sc., lett. et arti, 
1866, Sér. 3, tome i. 

10 Weiss, Sitzungsh. d. k. Akad. d. Wissensch., Wien, Bd. lxiv. ; Aldehoff, Zéschr. f. 
Biol., Miinchen, Ba. xxv. S. 137. 

11 Dissertation, Zurich, 1875. 


THE EXTRACTIVES OF MUSCLE. 105 


Work.—During work the glycogen disappears, being perhaps 
ei into sugar and the products of its combustion, of which 
lactic acid may be an intermediate one! (Weiss, Manché, Monari). 
This loss of glycogen is shown by numerous analyses, of which the 
following from Manché will serve as a type :— 


Percentage of Glycogen in | 


z ge loss of Glycogen 
opposite Limb, which was made | Percentage loss of Glyc 


Percentage of Glycogen in 
in Tetanised Limb. 


Limb at rest. 


to contract for 23-65 minutes. 


1 0°1277 0°114 12°76 
2 0°2287 0°1942 15:09 
3 0°2267 0°1917 15°44 


3. Removal of liver.—Minkowski, Laves,? and Schmelz# find that 
after removal of the liver the muscle glycogen rapidly diminishes. Some 
observers,? however, consider that the muscles have a glycogenic 
function apart from that of the liver. 

4, Cutting the nerve of a muscle causes an accumulation of glycogen 
in the muscle so paralysed.® 

5. Cutting the tendon of a muscle produces the same effect.’ 

6. Ligature of the artery of a muscle leads to a decrease in its 
glycogen, especially if cedema follows the operation, the accumulated 
lymph leading to saccharification (Chandelon, Manche). 

Sugar—During life the sugar in muscle is at a minimum; it 
increases after death as the glycogen disappears. The sugar is not 
maltose, as Nasse® supposed, but dextrose, as Meissner? suggested ; the 
work of Panormoff!° with the phenylhy drazine reaction has “placed this 
beyond doubt. Small quantities of dextrin are found as an intermediate 
product. 

Inosite—The occurrence of this substance in voluntary muscle 
has been noted by Scherer}? and Limpricht; in unstriated muscle by 
Lehmann; and in heart muscle, where it is more abundant than in 
skeletal muscle, by Boruttau.™ 

Fat.—This is always obtained from muscle, though whether any 
occurs in the true muscular substance apart from the entangled 
adipose tissue, it is difficult to say. Dormeyer * finds that after muscle 
has been subjected to preliminary gastric digestion, ether extracts 8°5 


1 Weiss, Joc. cit. ; Manché, Zischr. f. Biol., Miinchen, Bd. xxv. S. 163 ; Monari, Chem. 
Centr.-Bl., Leipzig, 1889, Bd. ii. S. 372. 

2 Arch. J. exper. Path. uv. Pharmakol. , Leipzig, Bd. xxiii. S. 139. 

3 Inaug. Diss., Konigsberg, 1886. 

4 Zischr. f. Biol., Miimchen, Bd. xxv. S. 180. 

> Prausnitz, [bid., Bd. xxvi. S. 377 ; Schmelz, Zoc. cit. 

® Chandelon, Arch. 7. d. ges. Physiol., Bonn, Bd. xiii. S. 626 ; Manché, Joc. cit. 

7K. Krauss, Virchow’s Archiv, Bd. exiii. S. 315. 

8 Zur. Anat. u. Physiol. der quergestreiften Muskel,” Leipzig, 1882. 
a ee v. d. k. Geselisch. d. Wissensch. u. d. Georg- Aug.- -Univ., Gottingen, 1861, S. 206 ; 

62 157. 

0 Zeschr. S. ph ysiol. Chem., Strassburg, Bd. xvii. 

1 Nasse, loc. cit. ; Limpricht, loc. cit. 

2 Ann. d. Chem. , Leipzig, Bd. Ixxvii. 8. 322. 

3 Zischr. f. physiol Chem., Strassburg, Bd. xviii. S. 513. 

4 Arch. f. d. ges. Physiol., Bonn, 1896, Bd. Ixy. S. 90. 


106 THE CHEMISTRY OF THE TISSUES AND ORGANS. 


per cent. more of the total fat obtainable; without such preliminary 
digestion, extraction with ether is useless for quantitative purposes.  E. 
Bogdanow ! believes that the fat which is thus soluble in ether with 
difficulty is a real constituent of the muscle plasma, and states that it is 
richer in volatile fatty acids than that from the surrounding connective 
tissues. For “ Adipocere,” see p. 20. 

Lactic acids—Among the oxypropionic acids with the empirical 
formula C,H,O,, one called hydracrylic acid, or ethylene lactic acid, CH, 
(OH).CH,.COOH, is not found in the body. Small quantities of this 
inaterial were formerly described? as occurring in muscle extracts, but 
this is not the case; the acid mistaken for it was acetyl-lactic acid 
H,CH(C,H,0,)COOH.? 

The remaining lactic acids are stereochemical isomerides of 
ethylidene lactic acid. They are three in number, and differ in optical 
activity, and in the solubility, optical activity, and amount of crystallisa- 
tion water in their zine, calcium, and lithium salts.* 

Their formula is CH,.CH(OH).COOH. The differences between 
them are due, according to the theory of Bel and Van’t Hoff, and as the 
expression stereochemical imples, to the space relationships of the atoms. 

The three isomerides are— 

(a) The optically inactive acid. This is the ordinary fermentation 
lactic acid, which occurs in milk when it turns sour; it has been found 
in small quantities in muscle,> in the grey matter of the brain, and in 
some cases of diabetic urine. Its most characteristic salts are— 


Zine lactate Zn(C,H.O,),+3H,O; soluble in fifty-three parts of water 
at 15°; in six parts at 100° C.; almost insoluble in alcohol. 

Calcium lactate, Ca(C,H;O,),+5H,O; soluble in 9°5 of cold, and in 
all proportions in boiling water. Insoluble in cold alcohol. 


(6) Dextrorotatory lactic acid.—This is paralactic, or sarcolactic 
acid. This is the lactic acid par excellence of muscle. It is found in 
the blood’ particularly after muscular activity.® It is found in the 
urine after muscular activity,° during diminution of oxidation processes," 
in phosphorus poisoning, and after extirpation of the liver.” It is found 
as noted when we considered them, in many organs and tissues after 
death. Its best known salts are— 


Zine sarcolactate, Zn(C,H;O.),+2H,O. Soluble in 17°5 parts of water at 
15° C., and in 96:4 parts of boiling 98 per cent. alcohol. 


1 Arch. f. d. ges. Physiol., Bonn, Bd. lxv. S. 81. 

? Wislicenus, dnn. d. Chem. Leipzig, 1873, Bd. clxvii. S. 302. 

8 Siegfried, Ber. d. deutsch. chem. Gesellsch., Berlin, 1889, 8. 2711. 

+ On lithium lactates, see Hoppe-Seyler and Araki, Zéschr. f. physiol. Chem., Strassburg, 
1895, Bd. xx. S. 365. 

® Heintz, Ann. d. Chem., Leipzig, 1871, Bd. elvii. S. 314. 

® Gschleidlen, Arch. 7. d. ges. Physiol., Bonn, 1873-4, Bd. viii. S. 71. 

7 Liebig, dnn. d. Chem., Leipzig, 1847, Bd. lxii. 8. 326 ; Wislicenus, zbid., S. 302. 

8 Gaglio, Arch. f. Physiol., Leipzig, 1886, S. 400; Irisawa, Zéschr. f. physiol. Chem., 
Strassburg, Bd. xvi. S. 340. 

* Spiro, Ztschr. f. physiol. Chem., Strassburg, 1877, Bd. i. S. 111: v. Frey, Arch. f. 
Physiol., Leipzig, 1885, 8. 557. 

W Colasanti and Moscatelli, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1887, 
S. 212; Marcus, Arch. f. d. ges. Physiol., Bonn, 1886, Bd. xxxix. 8. 425. 

N Araki, Zischr. f. physiol. Chem., Strassburg, Bde. xv., xvi., xvil., and xix. 

12 Minkowski, Centralbl. f. d. med. Wissensch., Berlin, 1885, No.2; Arch. f. exper. Path. 
u. Pharmakol., Leipzig, 1886, Bd. xxi. 8. 40; Marcuse, oc. cit.; Nebelthau, Zéschr. f. Biol., 
Miinchen, 1889, Bd. xxv. S. 123. 


a 


THE EXTRACTIVES OF MUSCLE. 107 


Calcium sarcolactate, Ca(C,H,O.),+4 or 44 H,O. Soluble in 12:4 parts 
of cold water and in all proportions of boiling water or alcohol. 
These salts are levorotatory, though the free acid is dextrorotatory. 


(c) Levorotatory lactic acid. This is produced by the fermentation 
of cane-sugar by means of a 
special kind of bacillus, and 
is also found in cultures of 
Gaffky’s typhoid bacillus in 
a solution of sugar and pep- 
tone.2 Very little is known 
about it yet. 

In all cases where three 
isomerides exist, as in the 
present case—one optically 
inactive, one levorotatory, 
and the third dextroro- 
tatory—it should be under- 
stood that strictly speaking 
there are only two isomer- 
ides, one dextro- the other 
levorotatory, the third or 
inactive variety being a com- 
pound of the other two. Fic. 18.—Zine sarcolactate.—After Kiihne. 
This was first shown by 
Pasteur ® in connection with racemic acid, which is optically inactive. 
By appropriate methods of crystallisation it can be separated into two 
varieties of tartaric acid, one dextrorotatory, the other levorotatory. 

Another method of separating 
an optically inactive material into” Ff PREY 1 Ta 
its optically active coniponsary ! j | 
has been alluded to on p. 52, in 
connection with glutaminic acid 
and leucine. It consists in allow- 
ing moulds, lke Penicillium 
glaucum, to grow in a solution of 
the inactive compound ; one only 
of its active components is des- 
troyed by the mould, and the 
other remains untouched. In the 
case of optically inactive lactic 
acid, the question has been 
attacked by the method of = . ! 
crystallisation of various of it Fic. 19.—Calcium sarcolactate.—After Kiihne. 
compounds, particularly of those 
with strychnine, and also of zinc ammonium lactate.* 

The mode of formation of lactic acid in muscles has been the subject 
of numerous researches. That the acid is sarcolactic acid has een 


1 Schardinger, Monatsh. f. Chem., Wien, Bd. xi. 
* Blachstein, Arch. de sc. biol., St. Petersbourg, tome i. p. 199. 
3 Ann. de. chim, Paris, Sér. 2, tome xxiv. p. 442; xxviii. p. 56; Compt. rend. Acad. 
d. sc., Paris, tome xxxvi. p. 26; xxxvii. p. 162; Ann. d. Phys. u. Chem., Leipzig, Bd. 
Ixxx. S. 127 ; xc. S. 498, 504. 
4 Purdie and Walker, 7’rans. Chem. Soc. London, 1892, p. 754; 1893, p. 1143. 


108) THE CHEMISTRY OF THE TISSUES AND ORGANS. 


stated by Berzelius Du Bois-Reymond,? Kiihne,® and Heidenhain.4 It 
may be readily detected in an ethereal extract by Uffelmann’s reaction.® 

Lactic acid is formed, not only after death, but also on activity 
during life; it is doubtless one of the acid products the accumulation 
of which produces fatigue,’ though the possibilities of basie products 
being also produced and causing fatigue by their influence on the 
central nervous system should not be overlooked." 


A number of recent researches have, however, thrown doubt on the ques- 
tion whether any free lactic acid is actually formed under these circumstances. 
In determining this question, it is very important to know the indicator 
employed in the investigation ; but even with the same indicator the results 
obtained by different workers are sometimes discordant. One of the best 
indicators for detecting weak acids is phenolphtalein. 

Moleschott and Battistini® found a rise of acidity during rigor, while 
Blome® did not. Warren! finds in fatigue that the acidity is increased, 
but that the number of acid molecules is diminished. This is explained by 
supposing that in resting muscle the anhydride, and in contracting muscle 
the free acid, is present, which latter combines with twice as much base as 
the anhydride. 

Gleiss |! agrees with the generally accepted view, that the acidity of contract- 
ing muscle is due to lactie acid, and finds that the slowly contracting red 
muscles of the rabbit, or the very slowly contracting muscles of the tortoise, 
become acid less rapidly than ordinary voluntary muscles. 

Weyl and Seitler !* were the first to point out that the increase of acidity 
may be at least in part due to acid potassium phosphate, produced from the 
alkaline phosphate by the development of new phosphoric acid from organic 
compounds, like lecithin and nuclein. Irisawa!® takes a similar view in 
reference to the acidity of dead organs like the liver and pancreas. The 
most careful work in this direction, however, is that of Réhmann.“ He used 
lacmoid and turmeric as indicators, and found that fresh muscle is alkaline to 
lacmoid, and neutral or weakly acid to turmeric. During tetanus and rigor, 
the alkalinity to lacmoid decreases, and the acidity to turmeric increases. He 
attributes the acid reaction to monopotassium phosphate (KH,PO,), and 
the alkaline reaction to dipotassium phosphate (K,HPO,), and to sodium 
bicarbonate. If lactic acid is formed, none is free. He admits that ether 
will extract lactic acid from muscle, but it will do so from alkaline muscle, 
and is produced by monopotassium phosphate turning it out of combination 
during the process of extraction. 


With regard to the origin of lactie acid, O. Nasse believes it comes 
from the glycogen. This is the simplest view of the matter to take, 
and it is supported by some work of Ekunina.” Many facts, however, 
do not fit in with this explanation; and the view very generally held 


‘“Lehrbuch d. Chem.,” vol. vi. p. 557. 
‘“*Gesammelte Abhandl. zur allgemein. Muskel und Nerven Physik,” Leipzig, 1877. 
‘““Untersuch. ii. das Protoplasma,” Leipzig, 1864. 
‘“Mechanische Leistung,” Leipzig, 1864, S. 143. 
A dilute solution of ferric chloride and earbolic acid, which is violet, is turned yellow 
by a trace (1 in 10,000) of lactic acid (Ztschr. f. klin. Med., Berlin, Bd. viii. S. 392). 

* Ranke, ‘‘Tetanus,” Leipzig, 1865, p. 350. 
A. Mosso, Trans. Internat. Med. Cong., Berlin, 1890. 

8 Arch. ital. de. biol., Turin, vol. viii. p. 90. 

° Arch. f. exper. Path. u. Pharmakol., Leipzig, 1890, Bd. xxviii. S. 113. Blome’s 
results have been much criticised by Réhmann ; Arch. f. d. ges. Physiol., Bonn, 1892, Bd. 
1. S. 84, zbid., 1898, Bd. lv. S. 589. 


ao. WW we 


-I 


1 Arch. f. d. ges. Physiol., Bonn, Bd. xxiv. 8. 391. 1 Ibid., Bd. xli. S. 69. 
2 Zischr. f. physiol. Chem., Strassburg, Bd. vi. S. 557. 13 Tbid., Bd. xvii. 8. 340. 
te W700. Cle. 9 Journ. f. prakt. Chem., Leipzig, N.F., Bd. xx. 


INORGANIC CONSTITUENTS OF MUSCLE. 109 


is that the acid arises from the decomposition of complex molecules, 
of which proteid forms a part. It is quite possible that the lactic acid 
may originate in both ways. 

The idea that the acid has a proteid origin was mooted by Kiihne ! 
in some of his earliest observations. He showed that not only is the 
acid formed during rigor mortis, but also during the heat-coagulation of 
myosin. Bohm? supported the proteid origin of lactic acid, and his view 
was endorsed by Hoppe-Seyler.? Some of my own experiments showing 
the development of acid during the coagulation of pure myosin,t and 
Latham’s theoretical views® on the constitution of the proteid mole- 
cule, tend in the same direction. Araki® found that diminution of 
oxidation in the body, such as is produced by the inhalation of carbonic 
oxide, leads to the appearance of lactic acid (and sometimes albumin 
and sugar) in the urine. This is accompanied by increase in proteid 
katabolism; and this again, as Hammarsten’ points out, is in favour of 
the same view. 

Inorganic constituents of muscle.—The total ash is from 1 to 1:5 
per cent. In it may be noted the predominance of potash among the 
bases, and of phosphoric acid among the acids. The following analyses 


are by Bunge :°— 
In parts per 1000. 
I I 


1 6 gat 4-160 
Nao .°- . bimorge 0-811 
B2Oiul yo!) aNOrORb 0-072 
MeOwy su. iovebuifem Ga 0:381 
FeO. ais) anol ahO-O57 ne 
MOaidtin vccu sete 458 
Cl re 0-70 
SO, 3: 0-10 


More recent work on this question is by J. Katz.® The flesh of a 
large number of animals was investigated. The following figures give the 
minimum and maximum in 1000 parts of fresh flesh —:K, 2:4 to 46; Na, 0°3 
to 15; Fe, 0-04 to 0°25; Ca, 0°02 to 0°39; Mg, 0°18 to 0°37; P (from 
phosphates), 1°22 to 2-04 ; (from lecithin), 0°13 to 0°48 ; (from nuclein), 0-09 to 
032; Cl, 0°32 to 0°8. 


Chemical changes accompanying the contraction of muscle — 
The physiology of muscular contraction, the influence of muscular 
work in metabolism, the gases of muscle, and other problems, will be 
studied in other portions of this work. It may not be inappropriate here, 
however, to conclude this section by stating briefly the main facts, 
haying a chemical bearing, relating to changes accompanying muscular 
contraction. The changes are in kind similar to those which occur in 


1 Arch. f. Anat. u. Physiol., Leipzig, 1859, 8. 795 ; ‘‘ Myologische Untersuch.,”’ Leipzig, 
1860, p. 184. 

= fa f. d. ges. Physiol., Bonn, Bd. xxiii. S. 44. Ina later paper (ibid., 1890, Bd. xlvi. 
S. 265) Bohm reaffirms his position in reference to some criticisms of Werther (ibid., S. 53). 

3 << Physiol. Chem.,” S. 666, 667. 

4 Journ. Physiol., Cambridge and London, 1887, vol. viii. p. 154. These results, how- 
ever, are criticised by v. Fiirth. 

° Brit. Med. Jowrn., London, 1886, vol. i. p. 630. 

6 Loe. cit. (Note 11, p. 106). 

7 «* Physiol. Chem,” 3rd German edition, S. 332. 

8 Zischr. f. physiol. Chem., Strassburg, Bd. ix. S. 60. 

® Arch. f. d. ges. Physiol., Bonn, 1896, Bd. xiii. 8. 1-85. 


110 THE CHEMISTRY OF THE TISSUES AND ORGANS. 


muscles during so-called rest; there is an exaggeration of the normal 
“chemical tone” of the tissue, and an explosive liberation of energy. 

1. Change in reaction.—The muscle becomes acid; this is generally 
believed to be due to the production of sarcolactic acid. The views 
of Rdhmann and others in relation to this question (see p. 108) deserve, 
however, careful consideration. 

2. Changes in the proteid—There is no marked and immediate 
increase of urea in muscular activity, though recent work tends to show 
that proteid katabolism is increased, and that the increase in urea 
leaves the body the next day or the day after. The main work, 
however, appears to fall on the non-nitrogenous part of the muscle, as 
evidenced by the immediate and large increase in the amount of 
carbonic anhydride that leaves the muscle. Hermann’s theory of 
muscular contraction assumes that the change is similar in kind to that 
which occurs on death, though less in degree. On death, he assumes 
that the hypothetical molecule he terms znogen’ is split mto carbonic 
anhydride, sarcolactic acid, and myosin. But anything like the 
formation of a clot of myosin has never been observed in living con- 
tracting muscle. 

3. Changes in the extractives—During tetanus the extractives 
soluble in water decrease, and those soluble in alcohol increase.” 
This appears to be chiefly explicable by the disappearance of glycogen, 
and appearance of sugar and lactic acid. 

A. Changes in the gases—Hermann’s theory just referred to was 
largely the outcome of his failure to discover oxygen among the gases 
of muscle. The oxygen used in the formation of carbonic anhydride 
must therefore be held in complex union within the muscle. On 
contraction, as on the occurrence of rigor mortis, the amount of 
carbonic anhydride given off is increased. The amount of oxygen 
absorbed from the blood is also raised, but not in proportion; hence the 
fraction ee eorbe a rises. (See more fully “ Respiration ”)- 

5. Production of reducing substances—Resting muscle oxidises 
pyrogallic acid ; tetanised muscle does not. A solution of nitrites 
passed through contracting muscle is changed into one of nitrates, and 
the colour of solutions of indigo sulphate is altered in the same 
way as by reducing agents* A. Schmidt* arrived at the same 
conclusion from the examination of the venous blood of tetanised 
muscle, but what the reducing substances are that are produced is 
quite unknown. 

Electrical organs.—From the torpedo organ, Weyl? extracted, 
probably from the mucous fluid between the plates, a “torpedo mucin.” 
This, however, yields no reducing sugar. A small quantity of gelatin 
and a globulin (coagulated by heat at 55°-60°) were also obtained.® 
The tissues like muscle, becomes acid and less transparent after 


1 The nearest approach to Hermann’s theoretical substance, inogen, is Siegfried’s phospho- 
carnic acid (see p. 103). 

2 Helmholtz, Arch. f. Anat. u. Physiol., Leipzig, 1845, S. 72; Ranke, ‘‘ Tetanus,” 
Leipzig, 1868; Heidenhain, Arch. f. d. ges. Physiol., Bonn, Bd. ii. 8. 574. 

3 Griitzner, ibid., Bd. vii. S. 255; Gscheidlen, ibid., Bd. viii. S. 506. 

4 Sitzungsb. d. k. Akad. d. Wissensch., Wien, Bd. xx. 

> Ztschr. f. physiol. Chem., Strassburg, Bd. vi. S. 525. 

6 Kriikenberg was unable to obtain myosin (‘‘ Weitere Untersuch. zur vergleich. 
Muskelchem.” Vergleich. physiol. Studien, 2 Reihe, Abth. 1, S. 143-7). 


THE SKELETAL TISSCES. POE 


death. Weyl? found the percentage of water in the muscles of 
torpedo to be 77:5; in the electrical organ, 89. He was also able to 
separate a number of organic substances from the organ, similar to 
those occurring in muscle and nerve, such as creatine, xanthine, 
lecithin, fat, cholesterin, fatty acids, and inosite. Frerichs and 
Stiideler found urea. In another research, Weyl? found that excitation 
of the organ produced an increased formation of phosphoric acid in it. 


THE SKELETAL TISSUES. 


Most of the chemical substances occurring in the connective tissues 
(collagen, elastin, mucin, fat) have been already described (see pp. 69-72). 
There are still a few to be discussed, which will be most conveniently 
done under the heads—Bone, Tooth, Cartilage, and Notochord. 

Bone.—Bone differs from most other tissues in its high percentage of 
mineral matter. It contains 46°7 per cent. of water,t of which Aeby ® 
considers 11 or 12 are in a state of loose chemical combination, 
analogous to water of crystallisation. 

The composition of undried bone without separation of marrow or 
blood is given by Hoppe-Seyler thus : — 


Water, 50°00 per cent. | Ossein, 11-40 per cent. 
ah Ab 75! 5 | Bone earth, 21°85 


3) 


Zalesky’s analyses of dried macerated bone are as follows :— 


Human Bone. Bone of Ox. Bone of Guinea-Pig. 
Organic constituents . : 34°56 32°02 34°70 


Inorganic : E 65°44 67°98 | 65°30 


Fossil bones analysed by Fremy® show a smaller percentage of 
organic matter. 

The organic constituents of bone are ossein or collagen, small quantities 
of elastin from the lining of the lacune and canaliculi,’ proteids, and 
nuclei from the cells,and a small quantity of fat even after the removal 
of all the marrow. The absence of mucin in compact bone is noteworthy, 
showing that the ground substance is entirely replaced by calcareous 
matter. Marrow, however, yields mucin. The inorganic constituents 
of bone are calcium phosphate, calcium carbonate, calcium chloride, 
calcium fluoride, magnesium phosphate, and small quantities of sulphates 
and other chlorides. 

1 Boll, Arch. f. Anat. u. Physiol., Leipzig, 1893, S. 99; Du Bois-Reymond found 
that the electrical organ of Malapterurus also becomes acid on activity. 

2 Monatsh. d. k. Akad. d. Wissensch., Berlin, April 1881. 

3 Arch. f. Anat. u. Physiol., Leipzig, 1884, Physiol. Abth., S. 316. 

4 Lukjanow, Ztschr. 7. physiol. Chem., Strassburg, Bd. xiii. S. 339. 

> Centralbl. f. d. med. Wissensch., Berlin, 1871, No. 14. 

6 Ann. de chim., Paris, Sér. 3, tome xliii. p. 47. 

7 This substance is not keratin, as Brosicke supposed. See H. E. Smith, Ztschr. f. 
Biol, , Miimchen, Bd. xix. S. 469. 


SR. A. Young, Journ. Physiol., Cambridge and London, 1892, vol. xiii. p. 803. 
® Rustiksky, Centralbl. f. d. med. Wissensch., Berlin, 1872, S. 562. 


12 THE CHEMISTRY OF THE TISSUES AND ORGANS. 


From a large number of analyses, Hoppe-Seyler gives the following 
figures representing percentages of the total ash :— 
Ca. PO,. CO,. Fl. Me. Cl. 
38°49 54°46 6°24 1:28 0-44 0-19 


From his own numbers, Zalesky has calculated the probable composition 
of the mineral constituents of bone as follows :— 


Caleium phosphate : : 2 83°889 
5 carbonate ; ’ , 13:032 
Calcium in combination with fluorine, 
chlorine, ete. . : : ; 0-350 
Fluorine ‘ . : : : 0:229 
Chlorine ; 3 3 : é 0183 


Hoppe-Seyler considered that the characteristic inorganic ingredient of 
bone, dentine, and enamel is one analogous to apatite. Apatite has the 
formula Ca,,FI,(PO,),, or Ca,,Cl,(PO,),. Very small quantities of these 
substances, however, occur in bone; the chief compound is one in which CO, 
takes the place of the Fl, or Cl,, namely, Ca,,CO,(PO,),. See, however, 
Gabriel’s researches below. 


Tooth.—The calcareous tissues of tooth are dentine, enamel, and 
crusta petrosa. The last named is bone; dentine is chemically similar 
to bone. Enamel, though epithelial in origin, may be conveniently 
taken here. 

Dentine—This consists of water 10 per cent., and solids 90 per cent. 
The solids are organic and inorganic. The organic solids are less 
abundant than in bone. They consist of collagen and elastin; the latter 
form the lining of the dentinal tubules. From Aeby’s analyses, Hoppe- 
Seyler gives the following table: 


Ca,,CO(PO,), . . 72°06 per cent. 
MeH(PO,) . : : ag. iA eae ee 
Organic substances ; vin, RMD 


Enamel.—This is the hardest tissue in the body. Hoppe-Seyler’s 
quantitative analyses give the following mean result :— 


Ge OOH (iO) A . 96-00 per cent. 
iv vole & 0 aa d ! Yee s@5 es 
Organic substances 3 th 6d be 


Various other investigators give numbers varying from 2 to 10 per 
cent. of organic matter. This they estimate by loss on ignition. Tomes,’ 
however, has recently shown that this loss is chiefly if not wholly due 
to water. On attempting to estimate the organic matter directly, 
none was found, or a quantity too small to be weighed. 

Gabriel? has recently worked at the question of the constitution of 
the mineral matter of bones and teeth. Some of his conclusions do 
not accord with the older work of Hoppe-Seyler. He finds that the 
constituents are water, lime, magnesia, potash, soda, phosphoric acid, 
carbonic anhydride, chlorine, and fluorime. The quantities of lime 
and phosphoric acid, which are the most abundant constituents, vary 

1 Journ. Physiol., Cambridge and London, 1896, vol. xix. p. 217; Trans. Odont. Soc. 


Gr. Brit., London, 1896. p. 114. 
2 Ztschr. f. physiol. Chem., Strassburg, Bd. xviii. S. 257. 


—_o 


CARTILAGE. 113 


but little, and are proportional to each other; the amounts of magnesia 
and carbonic anhydride are also proportional the one to the other. 
The amount of potash is greater than that of soda. The amount of 
chlorine is very small, and is greater in the teeth (0-21 per cent.) than 
in bone. Fluorine is a minimal constituent of both!; as a rule, not 
more than 0-05 per cent. is present. 

Water is present in two forms; one part passing off at 300°-350° C. 
is similar to water of crystallisation; the other part is only expelled by 
fusion with silicic acid, and is an expression of the basicity of the 
phosphate, and is called water of constitution or acidic water. 

The composition of the ash finds its simplest expression in the 
formula, Ca,(PO,),-Ca;HP,O,,+Aq, in which 2 to 5 per cent. of 
the lime is replaced by magnesia, potash, and soda, and 4 to 6 per cent. 
of the phosphoric acid by carbonic anhydride, chlorine, and fluorine. 
The limit of variation is, however, small, and the differences between 
bone ash and tooth ash are not greater than those between the ash of 
different bones. 

The notochord.—Sternber g? found that neither gelatin nor chondrin 
is obtainable from the notochord, and Neumann® that the cells stain 
with iodine as though they contained glycogen. Kossel* obtained a con- 
siderable supply of material from large lampreys, and found that it 
contains 95—96 per cent. of water ; this contrasts strongly with cartilage, 
and corresponds with what one finds in other embryonic tissues. The 
amount of ash is 0°85 per cent. The amount of glycogen constitutes 
from 12 to 15 per cent. of the solids present; the high percentage of 
this substance is another feature common to embryonic structures. 
There is not much more than a trace of proteid matter soluble in water. 
Gelatin, collagen, and mucin are all absent; the bulk of the solid matter 
is an insoluble proteid easily digested by artificial gastric juice; it yields 
no sugar on treatment with mineral acids. 

Cartilage. —The following analyses by Hoppe-Seyler exhibit the 
relative proportions of the ‘chemical constituents of human hyaline 


cartilage. In 1000 parts— 
Costal Cartilage. | Articular Cartilage. 


Water . ; : : : 676°6 735°9 
Solids . . : 323°3 264:1 

Organic solids ; : 301°3 248°7 

Inorganic solids. ; 22°0 15°4 
Potassium sulphate (in a hundred parts of ash) . 26°66 
Sodium sulphate " i . 44°81 
Sodium chloride As 4 . Sb Galil 
Sodium phosphate k, xs 8°42 
Calcium phosphate es % 788 
Magnesium phosphate 73 x 4°55 


The organic solids consist in small part of those in the cells, 
which are of the usual proteid nature, together with small quantities 
of fat and glycogen, demonstrable by micro-chemical means; but the 


1 For recent estimations of fluorine in bone and teeth by Carnot’s method (Compt. rend. 
Acad. d. sc., Paris, tome exiv. p. 750), see Gabriel, Ztschr. f. anal. Chem., Wiesbaden, 
Bd. xxxi. S. "522; and Waampelmeyer, ibid., Bd. xxxii. 8. 550. 

2 Arch. f. Physiol., Leipzig, 1881, S. 105. 

3 Arch. f. mikr. Anat., Bonn, Bd. xiv. S. 54. 

+ Ztschr. f. physiol. Chem., ; Strassburg, Bd. xv. S. 331. 


VOL. I1.—8 


114 ZHE CHEMISTRY OF THE TISSUES AND ORGANS. 


great bulk of the organic solids is derived from the matrix of the 
cartilage. 

In fibrocartilage, the hyaline matrix is‘ pervaded either by white 
fibres (white fibrocartilage), or by yellow fibres (yellow or elastic fibro- 
cartilage). 

In contrast with true bone, the analysis (by Frémy) of the calcified 
cartilage of the ray may be here given :— 


Ash per cent. . : . 30°00 | Calcium carbonate . ye) es 
Calcium phosphate . SST Magnesium phosphate, traces. 


The matriz of hyaline cartilage-—The organic basis of the matrix was 

formerly described as chondrigen; and just. as gelatin is obtained from 
collagen on boiling, so chondrin is obtained by boiling chondrigen. 
Chondrin, like gelatin, gelatinises on cooling a solution of it made with 
warm water, but in many of its reactions it differs from gelatin. 

Elementary analyses of chondrin, however, showed very great dis- 
crepancies, and Morochowetz! arrived at the conclusion that chondrin is 
not a chemical unit but a mixture of gelatin and mucin. This conclusion 
has been more recently amplified by “C. T. Mérner2 who worked under 
the superintendence of Hammarsten. 

The matrix contains four substances—(1) collagen, (2) an albuminoid, 
(5) chondromucoid, and (4) chondroitin- -sulphuric acid. Of these con- 
stituents the last two, with perhaps a little collagen, lie around the cells, 
forming what Mérner calls chondrin balls; they correspond to the mucin 
of Morochow etz, or hyalogen of Krukenberg, and are coloured blue by 
methyl-violet. They lie in the meshes of a network composed of collagen 
and mucoid, which is stainable by tropzolin. 

These four constituents may be separated as follows. The mucoid 
and chondroitin-sulphuric acid are dissolved out with 0-2 to 0°5 per 
cent. solution of potash; the collagen is dissolved out by hot water, being 
converted into gelatin in the process; the albuminoid remains undissolved. 

(1) Zhe colle gen (differs from ordinary collagen in only containing 
16-4 per cent. of nitrogen. 

(2) The albuminoid, which is found only in late adult life, is a proteid- 
like substance of an insoluble nature. It contains loosely combined 
sulphur. It differs from elastin in its high percentage of sulphur (see p.73). 

(5) Chondromucoid. — This substance has the following percentage 
composition :—C, 47°35; H, 642; N, 12°58; 8, 2-42; O, 31:28 (Morner). 
The sulphur is loosely combined. Chondromucoid gives the ordinary 
proteid reactions. On decomposition, it yields the usual decomposition 
products of proteids, with chondroitin-sulphurie acid in addition; this 
latter substance is, on further decomposition, broken up into sulphuric 
acid and a reducing substance. Schmiedeberg* regards chondromucoid 
as a union of proteid with chondroitin-sulphurie acid, 

(4) Chondroitin-sulphuric acid.—This substance was called chondroitic 
acid by Bédeker* and Krukenberg® (who classed it among his hyalins, 


1 Verhandl. d. naturh.-med. Ver. zu Heidelberg, Part 5, Bd. i. 
2 Zischr. f. physiol. Chem., Strassburg, Bd. xii. 8. 396; Skandin. Arch. f. Physiol., 
Leipzig, Bd. i. S. 210! 
® Arch. f. exper. Path. u. Pharmakol. , Leipzig, 1891, Bd. xxviii. 8. 355. 
4 Ann. d. Chem., Leipzig, 1861, Bd. exvii. S. 111. 
5 Ztschr. f. Biol., , Munchen, Bd. xx. S. 307. 


"ae 


—or 
; 


NERVOUS TISSCUES. 115 


see p. 64). It was first prepared in a pure condition by Morner, and 
its constitution made out by that observer and by Schmiedeberg. It is 
partly found as such in the cartilaginous matrix, but most originates 
from the decomposition of chondromucoid. 

Morner found that the sulphur in it was all in the form of ethereal 
hydrogen sulphate; hence the name chondroitin-sulphuric acid. It is 
almost, but not quite, characteristic of cartilage. Mérner? separated it 
from twenty different varieties of cartilage, from cartilagmous tumours, 
and also from the tunica intima of the aorta,? but from no other tissue 
or organ of the body.’ 

Schmiedeberg ascribes to it the formula C,,.H,,NSO,,.. On decom- 
position, the first products are sulphuric acid, and a nitrogenous sub- 
stance chondroitin. 


C,,H,,NSO,,+H,0 =H,80,+C,,H,,NO,, 
(chondroitin-sul- (water) (sulphuric (chondroitin) 
phurie acid) acid) 


Chondroitin is a gummy material, and a monobasic acid. On 
hydration it yields acetic acid, and a new nitrogenous body called 
chondrosin. 

C,;H,,NO,,1+3H,0 = C,H,0,7C,,H,,NO,, 


(chondroitin) (water) (acetic acid) (chondrosin) 


Chondrosin is also gummy, and a monobasic acid. It reduces 
Fehling’s solution even more strongly than dextrose; it is dextro- 
rotatory, and is the reducing substance which so many previous chemists 
have obtained in an impure form from cartilage. On further decomposi- 
tion it yields glycuronic acid (see p. 5) and glucosamine (see pp. 9 and 75). 


Nervous TISSUES. 


General composition.—The amount of water varies. It is present 
in larger amount in the grey than in the white matter, in early 
than in adult life, in the brain than in the spinal cord, in the spinal 
cord than in nerves. These facts are illustrated by the following 

a table>— 


PORTION or Nervous | PERCENTAGES OF WATER. 


SYSTEM. 

: ~ oO © 2 | on | | } 
mw) ny | Ag a, (B.) P.) | AL) | (R.) | 
| | | 
Grey matter ain core 83 84 | 85 81) f\--86— 
White _,, a UN ye Or ey ee io 

Spinal cord pee 3. | ate | 73-76 68 
Nerves . He 64-72 | 57 | 


1 Zischr. f. physiol. Chem., Strassburg, 1895, Bd. xx. S. 357. 

* Upsala Likaref. Férh., Bd. xxix. 

3 Oddi (Arch. f. exper. Path. u. Pharmakol., Leipzig, Bd. xxxiii.) states he has obtained 
it from livers which had undergone amyloid degeneration. 

4 In the above table, (W.) refers to Weisbach (Hofmann’s ‘‘ Lehrbuch d. Zoochemie,” Wien 
1876, S. 121); (B.) to Bernhart (Gamgee’s ‘‘ Physiol. Chem.,” vol. i. p. 446); (P.) to 
Petrowsky (Arch. f. d. ges. Physiol., Bonn, Bd. vii. S. 367); (M.) to Moleschott (Charles, 
** Physiol. Chem.,” p. 335); and (R.) to de Regibus (Jahresb. ii. d. Fortschr. d. Thier- 
Chem., Wiesbaden, Bd. xiv. 8. 346). 


116 LHE CHEMISTRY OF THE TISSUES AND ORGANS. 


Solids. —The solids may be divided into the following classes :— 

(a) Proteids.—These comprise a very considerable percentage of the 
solids, especially in the grey matter (over 50 per cent.). 

(>) Neurokeratin and nuclein. 

(c) Phosphorised constituents ; especially protagon and lecithin. 

(7) Cerebrins.—Nitrogenous substances of unknown constitution. 

(¢) Cholesterm.—Especially abundant in white matter. 

(f) Extractives.—Creatine,! xanthine,? hypoxanthine? inosite,? lactie 
acid,® leucine,® uric acid,? and urea. 

(7) Gelatin and Fat.—From the adherent connective tissue. 

(1) Inorganic salts—The total mineral matter varies according to 
different writers from 0-1 to 1 per cent. 
, Geoghegan * gives the following figures in parts per thousand of 

rain :— 


Total ash 29.“ todel Chlorine . , : 0-4 to 12 
Potassium. ‘ 0-6 ad Mey PO, ; 2 : 0:9. 28 
Sodium : : O-4 falat CO, ‘ : : O25 On 
Magnesium O70. 5907 Oe : : 0: Babee 
Calcium 0:005 ,, 0:02 | Fe(PO,), é ; 0:01, 0005 


The grey matter is stated by Schlossberger to be richer in total ash 
than the white, but poorer in phosphates; Petrowsky, on the other hand, 
found more phosphates in grey than in white matter. 

The following table gives some typical quantitative analyses which 
have been made of the proportion in which the principal solids eccur in 
different nervous structures :— 


F es ; Other 
Portion of Nervous penta. ill qe Sag Cholesterin my ba ee Neuro- ane {ore 
System. Proteids. | Lecithin. andewate Cerebrins. inarinih ona Salts. 
atters. 
| Pe Be a Se 
| Grey matter of ox | 55°37 17°24 18°68 | 0°53 671 145 
brain ? | 
| White matter of | 24°72 9°90 51-91. | 99555 3°34 0°57 
| ox brain? 
| es = — ee ES ee 
| Spinal cord& . | 23°8 fod ll 
| 
Gea ss 7 
Human - sciatic | 36°8 32°57 NQEAD 11°30 3°07 | 4°0 
nerve * | | 


The quantitative work I§ have done on this question may be sum- 


1 Miiller, Ann. d. Chem., Leipzig, Bd. ciii. S. 141; Stiideler, Journ. f. prakt. Chem., 
Leipzig, Bd. Ixxii. 8. 256. 
: *Stadeler, Ann. d. Chem., Leipzig, Bd. exvi. S. 102; Scherer, zbid., Bd. evil. 

. 314. 

3 Miller, Zoc. cit. ; see also Strecker, Ann. d. Chem., Leipzig, Bd. ev. S. 316. 

4 Ztschr. f. physiol. Chem., Strassburg, Bd. i. S. 330. 

° Petrowsky, loc. cit. 

§ Moleschott, Zoc. cit. 

7 Josephine Chevalier, Ztschr. f. physiol. Chem., Strassburg, Bd. x. S. 97. 

® Halliburton, Journ. Physiol., Cambridge and London, 1893, vol. xv. p. 90. 


PROTEIDS OF NERVOUS TISSUES. 117 


marised in the following table of mean analyses. The organs were from 
adult human beings, dogs, cats, and monkeys :— 


Water. Solids, | eRBeataiie 
in Solids. 

Grey matter of cerebrum . 5 83°467 | 16°533 | 51 

| White s! of ..| 69912 | 30-088 | 3s | 
Cerebellum. : ; 79°809 | 20°191 | 42 
Spinal cord asa whole. 3 71°641 28°359 | 31 
Cervical cord . : : : 72°529 27-471 | 31 
Dorsal cord. : ) , 69°755 30°245 28 
Lumbar cord . 3 : ; 72°639 27°631 | 33 
Siitieratiea!sl.. 4 oi oblate ei-suen lnd8-e84 post Boa aici] 

| 


This table illustrates the fact that the amount of grey matter, of 
water, and the percentage of proteid in the solids, vary directly the one 
with the other. This is very well seen in the different regions of the 
spinal cord. The percentage of proteid in the white matter of the 
brain is a little higher than in the spinal cord; this exception is 
perhaps to be explained by the high percentage of neurokeratin! in 
white matter, which, according to the methods used, would be included 
with the proteids. 

Reaction of nervous tissues.—Heidenhain? and Gscheidlen? state that 
the normal reaction of the axis cylinder is alkaline; on death or on 
long-continued activity the reaction becomes acid. They further state 
that the grey matter is acid even during life. O. Langendorff* found 
the reaction of the central nervous system alkaline during life; the 
alkalinity rapidly diminishes after death, or on stoppage of the circula- 
tion. §. Moleschott and Battistini® found both central and peripheral 
portions of the nervous system acid, especially the grey matter; this was 
increased by activity. 

In my own work | found in animals that the fresh tissues were 
invariably alkaline, but they became rapidly acid, especially the grey 
matter. Inthe human brains I received from the post-mortem room the 
reaction of the grey matter was always, of the white matter often, acid. 
This I put down to changes after death, for at least twenty-four hours 
had always elapsed since death. 

The acidity is due to lactic acid; but, according to Miiller and 
Gscheidlen, it is not sarcolactic acid but the fermentation lactic acid 
(optically inactive ethylidene-lactic acid). Miiller also obtained traces 
of formic acid. 

Proteids of nervous tissues.—The large quantity of these, especi- 


1 The percentage of neurokeratin is in grey matter, 0°3; in white matter, 2°2 to 2°9; and 
in nerve, 0°3 to 0°6 (Kiihne and Chittenden, Zéschr. f. Biol., Miinchen, Bd. xxvi. S. 291), 
2 Centralbl. f. d. med. Wissensch., Berlin, 1868, S. 833. 
3 Arch. f. d. ges. Physiol., Bonn, Bd. viii. S. 171. 
4 Neurol. Centralbl., Leipzig, 1885, No. 14; Centralbl. f. d. med. Wissensch., Berlin, 
1886, No. 25. 
° Arch. ital. de biol., Turin, vol. viii. p. 90; Chem. Centr.-B7., Leipzig, 1887, S. 1224. 


138 THE CHEMISTRY OF THE TISSUES AND ORGAMWS. 


ally in the grey matter, has been already alluded to. Petrowsky, in 
the investigation just mentioned, describes a globulin somewhat 
resembling myosin, and an albumin especially abundant in grey matter 
which is coagulated at a temperature of 75° C. Baumstark," in a more 
recent research, speaks of the chief proteid matter in nervous tissue as 
resembling casein; this is so, for it is a nucleo-proteid. My own con- 
clusions? on the subject are as follows :— 

The proteids present are three in number. The first is a globulin, 
coagulated by heat at 47° C., and analogous to the cell globulin deriy- 
able from nearly all cellular tissues. The second and most abundant is 
nucleo-proteid. Ina saline extract of nervous tissues it is mixed with 
the other proteids; attempts to prepare it by the sodium-chloride 
method failed. It may, however, be prepared in large quantities by 
precipitating an aqueous extract of brain by weak acetic acid (Wool- 
dridge’s method). The supply obtainable from white matter is small. It 
is coagulated at 56°-60° C.; it contains 0°5 per cent. of phosphorus, and 
gives the general reactions of nucleo-proteids, production of intravascular 
coagulation included. The third proteid is a globulin, coagulated by 
heat at 70°—75° C., and analogous to a similar globulin separable from 
liver cells (see p. 86). Peptone, proteose, myosin, and albumin are not 
obtainable. 

Protagon.—In the year 1865, Liebreich* separated from the brain 
a material he called protagon ; he further found that, when decomposed 
by baryta water, it yielded two acids—stearic acid and glycero-phosphorie 
acid—and a base choline. 

Hoppe-Seyler, and Diaconow * working under Hoppe-Seyler’s direc- 
tion, denied the existence of this substance, and considered that it was a 
mere mechanical mixture of lecithin with a nitrogenous non-phosphor- 
ised substance called cerebrin. Diaconow’s analyses were, however, far 
from convincing. 

The subject was taken up in this country by Gamgee and 
Blankenhorn, who showed that protagon is a_ perfectly definite 
erystalline substance of constant elementary composition. They also 
showed that even prolonged treatment with alcohol and ether will not 
extract lecithin from protagon, as alleged by Diaconow. When protagon 
is digested with alkalis it yields cerebrin or cerebrins, and the decom- 
position products of lecithin. This work has been confirmed by 
3aumstark,® Ruppel,’ and Kossel and Freytag.® 

Protagon is prepared as follows :—The brain is digested with alcohol 
at 45° C.; the extract is filtered warm, and cooled to 0° C. It then 
deposits a white precipitate of protagon mixed with cholesterin, which 
is dissolved out by means of ether. The protagon is dried, redissolved 
in warm alcohol, and erystallises out on cooling. The empirical formula, 
calculated from their analytical results, is given as C,,,H..N;,PO.; by 
Gameee and Blankenhorn. 


1 Ztschr. f. physiol. Chem., Strassburg, Bd. ix. 8. 145. 

2 Journ. Physiol., Cambridge and London, 1893, vol. xv. p. 100. 

3 Ann. d. Chem., Leipzig, Bd. exxxiv. S. 29. 

4 Centralbl. f. d. med. Wissensch., Berlin, 1868, S. 97. 

5 Journ. Physiol., Cambridge and London, vol. ii. p. 118 ; Gamgee’s ‘‘ Physiol. Chem.,” 
vol. i. p. 427. 

6 Zischr. f. physiol. Chem., Strassburg, Bd. ix. 8. 329. 

7 Ztschr. f. Biol., Miinchen, Bd. xxxi. 8. 86. 

8 Ztschr. f. physiol. Chem., Strassburg, Bd. xvii. 8, 431, 


THE CEREBRINS OR CEREBROSIDES. 119 


The percentage composition is seen in the following table :— 


| 
[tats 2 so ee 2UPPEL. Vier LATED | 
ELEMENTS. |LIEBREICH.! Branco BAUMSTARK. KOSSEL. | 7 FROM 
ORMULA. 
Ox. Human. 
| | 
C Hp 66274. 66°39 | 66°48 66°25 66°29 | 66°51 | 66°45 
H 11°74 TO-GS" > pera 1113 | 10°75 | 10°88 | 10-66 
N : 2°80 | 2°39 2°35 325 2°32 255. | 2°42 
IP eo 1:068 1°02 0°97 en) alse 1:07 
Ss ; 0°51 0°096 | 
O ; ~ Peg" eee so x) i 1940 | 
| } 


An elaborate research by Thudichum ! led him to the conclusion that 
there are three groups of phosphorised substances in the brain, which he 
termed kephalines (very soluble in ether), myelines (less soluble in 
ether), and lecithins (characterised by their extreme instability). In 
each of these ill-defined groups several members with their empirical 
formule are described. Thudichum’s work has been so far confirmed 
by that of Kossel, in that he has shown that protagon is not a single 
substance, but that there is more than one protagon. They yield either 
one or two or perhaps three derivatives (cerebrosides), called cere- 
brin, kerasin or homocerebrin, and encephalin; and, further, probably 
several lecithins are obtainable from the different protagons. The 
constitution of lecithin is discussed on p. 22, and there it will be seen 
that the existence of several lecithins (7.e. containing different fatty acid 
radicles) is mooted. The protagons, according to Kossel, resemble each 
other in the following points :— 

1. They contain carbon, hydrogen, nitrogen, oxygen, and phosphorus. 
Elementary analysis gives practically the same results as those obtained 
by other observers. But the existence of sulphur in some varieties of 
protagon is a new point. 

2. By oxidation with nitric acid they yield higher fatty acids (palmitic 
and stearic). 

3. By the action of boiling sulphuric or hydrochloric acid a reducing 
carbohydrate is formed. 

4. By the action of alkalis they yield cerebrosides (formerly called 
cerebrins). 

5. The cerebrosides are the source of the reducing carbohydrate 
mentioned above. 

6. The carbohydrate formed is galactose. 

7. Other decomposition products of the cerebrosides are ammonia, and 
a complex material which on fusion with potash yields higher fatty acids. 

The cerebrins or cerebrosides.—These substances, the glucoside 
constitution of which has just been alluded to, form a group of ill- 
defined, nitrogenous substances, existing especially in the white sub- 
stance of nervous tissue, and also in the yolk of egg, pus corpuscles, 
and spleen cells.” 


1 Rep. Med. Off. Privy Council, London, 1874, p. 113 ef seq. 
* Hoppe-Seyler, ‘‘ Physiol. Chem.,” 8. 720, 788. 


120° THE CHEMISTRY OF THE TISSUES AND ORGANS. 


Miiller! obtained cerebrin by rubbing brain up with baryta water, 
so as to form a milky fluid; this is boiled, and the resulting coagulum 
extracted with boiling aleohol; on cooling, the alcoholic solution deposits 
cerebrin and cholesterin. The latter is removed by ether, and the former 
is purified by repeated crystallisation from boiling alcohol. According to 
Miller, its formula is C,,H,,NO,; according to Parcus? C,)H4.N,0;;- 
Parcus also obtained two other similar substances (homocerebrin and 
encephalin) with different formule. Adopting a slightly different modus 
operandi, Geoghegan* obtained a substance with the formula CoE Se 
Thudichum 4 separated three cerebrins, which he named cerebrin 
(C.,H,g.N,O,), phrenosine® (C,,H,,NO,), and kerasine (C,H,,NO,). 
Gamgee® found that, while protagon cannot be separated by the simple 
action of solvents into lecithin and cerebrin, yet such non-phosphorised 
substances do exist by its side in the brain, and one which he called 
pseudo-cerebrin (C,,H,,NO,) can be obtained from protagon by the 
action of caustic baryta. 

The fact that the cerebrins are glucosides was known to Liebreich,’ 
Diaconow, Otto’ Geoghegan,® and Thudichum,” but it was only within 
quite recent years that the sugar was identified as galactose, almost 
simultaneously in this country and in Germany." 

The most recent work on the subject is that by Kossel and Freytag,” 
who adopt the very appropriate name of cerebrosides for these bodies. 
They find that these substances are constituents of the medullary 
sheaths rather than of the axis cylinders. They have especially worked 
at two, which they obtained by the decomposition of protagon crystals, 
namely, cerebrin and kerasin. The analyses of these agree very well 
with those previously published by Thudichum, Parcus, and others. 
Their molecular weight was investigated by Beckmann’s boiling method, 
and by the examination of their barium and bromine compounds. By 
treatment with nitric acid they yield not only galactose but also a 
fatty acid recognised as neurostearic acid by Thudichum, and correctly 
analysed but not identified by Miiller. It is, in fact, stearic acid, three 
molecules of which are formed from cerebrin for every two atoms of 
nitrogen. From all these considerations, the formula given to cere- 
brin is C.,H,,,.N.O,,, and to kerasin (the homocerebrin of Pareus), 
Cie NOs, 

Similar substances occur in other parts of the body; thus two 
separated from pus are named pyosin, C,-H,,)N.O,;,, or CgHyN,0,;, 
and pyogenin, CyH4.N.0,, These bodies and similar ones separated 
from testicular cells are components of the cell protoplasm, not of the 
nucleus (Kossel and Freytag). 


* Ann. d. Chem., Leipzig, Bd. ciii. 8. 131; ev. S. 361. 
2 Journ. f. prakt. Chem., Leipzig, Bd. exxxii. S. _ 
3 Zischr. f. physiol. Chem. , Strassburg, Bd. iii. S. 

+ Loc. cit. 

° For recent papers on phrenosine, see Thudichum, Journ. f. prakt. Chem., Leipzig, 
Bd. liii. S. 49 ; Kossel, ibid., 1896, Bd. liv. S. 215. 

6 Loc. cit. 

* Virchow's Archiv, Bd. xxxix. S. 183. 

Solid ee BU exe. 272 

® Geoghegan stated that the reducing substance had the formula C,,H,,;0, ; he termed 
it cetylid ; ; cetylid was no doubt a mixture of galactose and fatty acids. 

W Journ. f. prakt. Chem., Leipzig, Bd. xxv. S. 23. 

1 Thierfelder, Zischr. f. physiol. Chem., Strassburg, Bd. xiv. S. 209; Brown and 
Morris, Proc. Chem. Soc. London, 1889, p- 167. 

? Ztschr. f. physiol. Chem., Strassburg, Bd. xvii. S. 431. 


I SN PIPIE DS ‘Tem 


THe EYE. 


The cornea.—A thousand parts of corneal tissue contain 242 of 
solids, of which 204 consist of collagen, 28 of other organic matters, and 
10 of ash.t 

The erroneous idea that the cornea, like cartilage, contains a specific 
substance called chondrin (Miiller), was first combated by Morochowetz,? 
who showed that chondrin here as elsewhere is a mixture of gelatin and 
a mucinoid material. This latter substance is named by C. ii Morner, 
cornea-mucoid; its percentage composition is C, 50:16; H, 697; N, 
12°79; S, 2°07; O, 28°01. It resembles other mucoids very closely in 
its properties (see p. 63). The gelatin obtained from the collagen 
resembles that found elsewhere. The same mucoid and collagen are 
present in the sclerotic. 

Descemet’s membrane is resistant to reagents. Morner terms its 
chief constituent membranin. It belongs tothe mucoid group. The lens 
capsule has a similar chemical structure. 

The choroid and iris are principally of chemical interest from con- 
taining the black pigment which is identical with or nearly related to 
that in the pigment layer of the retina. 

The retina.—Cahn* gives the following table of the quantitative 
composition of the retinse of geese :— 


Water . ; ‘ é : : . 86 to 89 per cent. 
Solids . 3 ; : [4 ak = 
Proteids (globulin coagulating at 50° C., 


albumin and mucin (2)) : 4,, 6 n 
Gelatin ’ : : : ; : 1s igre! We a 
Cholesterin . : , , : : Oars be 
Lecithin. : : : : : EOS 29 E. 
Wai) . : : ! : : HT OORT O-Babe! 
Salts . ; : ; E : O-7 BUD f. 


The pigments of the retina—The black pigment of the retinal 
epithelium is called fuscin. In some animals the epithelium is free from 
pigment in part ; this constitutes the tapetwm lucidum. In some fish this 
contains crystals of guanine; in the ox and sheep it does not.* 

Fuscin is one of the group of black pigments, termed melanins. It 
was investigated by Berzelius, and by Heintz, who found it contained a 
small quantity of iron, by Scherer, who found no iron, and also by Rosow 
and Sieber. The percentage composition obtained by the various 
observers shows great discrepancies, and this, taken into account with their 
methods of preparing the pigment, renders it probable they were dealing 
with impure substances. The failure to find iron was due to the fact 
that hydrochloric acid was employed at one stage of the operations, 
and this dissolves out nine-tenths of the iron.® 


1 His, quoted by Gamgee, ‘‘ Physiological Chemistry,” vol. i. p. 451. 

2 Verhandl. d. naturh.. anell: Ver. zu Heidelberg, pes, BaF 1: 

3 Zischr. f. ph ysiol. Chem., Strassburg, Bd. xviii. S. 213. 

4 Hoppe-Seyler, ‘‘ Physiol. Chem.,” S. 699. 

> Kiihne and Sewall, Verhandl. d. naturh.-med. Ver. zu Heidelberg, N. ¥., Bd. ii 
Heft 5. 

6K. A. H. Morner, %schr. f. physiol. Chem., Strassburg, Bd. xi. S. 66. The pigment 
in the skin of negroes, and in melanotic sarcomata, is closely allied to fuscin. It appears 
to contain iron. In melanotic sarcomata, Berdez and Nencki named the pigment phyma- 
torusin ; in those of horses, hippomelanin. The subject of melanin in the urine has been 


122 THE CHEMISTRY OF THE TISSUES AND ORGANS: 


May’s method! of preparing fuscin is to boil retine in alcohol, then in 
ether, lastly in water. The residue is then subjected to tryptic digestion. 
Three things remain undigested ; of these nuclein is got rid of by tritura- 
tion with alkali; the second, neurokeratin, must be picked out with 
forceps ; the third is the pigment. 

Fuscin is slowly bleached in the air; it dissolves by boiling it a long 
time with concentrated sulphuric acid, or caustic alkalis. 

There is a considerable doubt, as in the ease of other melanins, 
such as those in the skin, whether or not it is derived from 
hemoglobin? Kriikenberg considers it is more closely related to 
the lipochromes. It is, however, undoubtedly nitrogenous. It is 
certainly not a member of the group of pigments occurrmg in 
plants named humous substances by Hoppe-Seyler,> since on fusing 
with alkali it yields no pyrocatechin or protocatechnic acid.t The 
chief interest of fuscin is not, however, chemical but physiological. 
Such problems as its varying distribution under the influence of hight 
and its relationship to the visual purple of the rods will be treated 
under “ Vision.’ 

Visual purple or rhodopsin.—We possess very little chemical 
knowledge of visual purple. Kiihne found it to be soluble in certain 
reagents such as solutions of bile salts, that in the process of bleaching it 
passes through a yellow stage, that the bleaching occurs at different 
rates at different temperatures and in different “eoloured lights, and 
that spectroscopically it cuts out a very considerable portion of the 
spectrum. It is destroyed by alcohol, ether, chloroform, and strong 
alkalis and acids, but not by most oxidising agents. It is perhaps 
related to the lipochromes. The green, yellow, and red pigments 
(chromophanes) of the oil droplets in ‘the cones of birds are undoubtedly 
lipochromes (see p. 20). 

The aqueous humour is lymph.’ In parts per 1000 it contains: 
water, 986°87 ; solids, 13°13; proteids, 1-22 ; extractives, 4:21 ; morganic 
salts, 7°70; sodium chloride, 6°89.6 It does not clot spontaneously, but 
does so on addition of serum. The proteids in it are fibrinogen, serum 
globulin, and serum albumin? Kiihne® found a reducing substance 
among the extractives. This is not sugar. Urea and sarcolactie acid 
are also present in small quantities.® 

The vitreous humour.—The membranes of the vitreous humour 


worked at especially by v. Jaksch. The following are references to the principal papers 
on the subject :—Morner, Zoe. cit., also ibid., Bd. xii. S. 229; Nencki, Arch. f. exper. 
Path. uw. Pharmakol., Leipzig, Bd. xxiv. S. 17, 27; Chem. Centr.-Bl., Leipzig, 1888, 
S. 587; Brandl and Pfeiffer, Ztschr. f. Biol., Miinchen, Bd. xxvi. S. 348; v. Jaksch, 
Ztschr. f. physiol. Chem., Strassburg, Bd. xiii.; Abel and Davis, Journ. Kaper. Med.. 
Baltimore, 1896, No. 3, vol. i.; Schmiedeberg, Arch. f. exper. Path. u. Pharmakol., 
Leipzig, S9/5 Bde xxxie Sele 
1 Untersuch. a. d. physiol. Inst. d. Univ. Heidelberg, Bd. ii. 8. 324. 

2 Delépine has even suggested that, in the case of the skin pigment, hemoglobin is derived 
from it (Proc. Physiol. Soc., London, Dee. 13, 1890, p. xxvii.). Abel and Davies (doc. cit. ) 
have recently studied the pigment of the negro’s skin. The granules contain inorganic 
matter as well as pigment. The latter contains the merest trace of iron. They conclude 
that it originates not from hemoglobin, but from the proteids of the tissue juice. 

° Zischr. f. physiol. Chem., Strass! urg, Bd. xiii. S. 66. 

4 Hirschfeld, ibid., Bd. xiii. S. 407. 

5 Chavvas, Arch. f. d. ges. Physiol., Bonn, Bd. xvi. S. 143. 

5 Lohmeyer. See Gorup-Besanez, ‘‘ Lehrbuch,” 4th edition, 1878, S. 401. 

7 Friend and Halliburton, Rep. Brit. Ass. Adv. Sc., London, 1889, p. 130. 

8 Arch. f. d. ges. Physiol., Bonn, Bd. xii. S. 200. 

® Grinhagen, ibid., Bd. xliii. S. 377; Pautz, Ztschr. f. Biol., Mtinchen, Bd. xxxi. 


aa 


THE LENS. £23 


yield gelatin. Its chief constituent is mucin, or mucinogen (Young), 
ealled mucoid by C. T. Mérner. According to the latter, this mucoid con- 
tains 12:27 nitrogen, and 1:19 sulphur, per cent. There are also small 
quantities of proteid. References to the papers of Young and Morner, 
the most recent workers on this subject, will be found on p. 62. 

The lens.—The following are the results of Laptschinsky’s 4 
analyses :— r 


Water . . 63°50 per cent. Cholesterin ? 0:22 per cent. 
Solids . ATBEHHO) 4 Fats . os YO201) ae 
Proteids 31OS4-93) ve Salts O:68" ms: 
Lecithin fur OLBS | lire | 


Fic. 20.—Absorption spectra of retinal pigments.—1, of visual purple ; 2, of visual yellow ; 
3, of xanthophane in ether; 4, of rhodophane in turpentine; 5, of chlorophane in 
ether. This diagrammatic way of representing absorption spectra indicates the thick- 
ness of the absorption-bands in solutions of different strengths; the top of each 
spectrum shows the thickness of the bands in a dilute solution; as the concentra- 
tion of the solution increases, the bands become wider, as in the lower part of each 
diagram.—After Kiiline. 


The proteid matter is thus very abundant; it is chiefly a globulin, to 
which Berzelius gave the name of crystallin. It has also been the 
subject of researches by Hoppe-Seyler, Laptschinsky, Kiihne, and C. T. 
Mérner.* According to the last-named investigator, about 52 per cent. 
of the proteid matter of the lens is insoluble in water and_ saline 
solutions. The insoluble proteid residue is an albuiminoid, and it is 


1 Arch. f. d. ges. Physiol., Bonn, Bd. xiii. S. 631. ; 

2 The cholesterin increases greatly in cataract (Cahn, Hoppe-Seyler’s ‘‘ Physiol. Chem.,” 
S. 692). 

3 Ztschr. f. physiol, Chem., Strassburg, Bd. xviii. S. 61. 


124 THE CHEMISTRY OF THE TISSUES AND ORGANS. 


most abundant in the inner denser portions of the lens. It yields 
no nuclein on gastric digestion; the small amount of phosphorus it 
contains is due to inorganic phosphates. The soluble proteids of the 
lens are also not nuclein compounds. About one per cent. of the 
soluble proteid is albumin; the rest is globulin. The globulin is 
precipitated by saturation with magnesium sulphate, but not with 
sodium chloride; in this it resembles vitellin. The globulin consists 
of two proteids, «-crystallin and $—crystallin. 

a—Crystallin is completely precipitable by saturation with magnesium 
sulphate or with sodium sulphate at 30° C., by the addition of one and a 
half times its volume of saturated ammonium sulphate solution, by a 
stream of carbonic anhydride, and by very dilute acetic or hy drochlorie 
acids. It coagulates at 7 72°C. It contains: N, 16°68; 8, 0°56; C, 52°83; 
and H, 6:94 per cent. ee oa: oe 

B- Crystallin differs from this in its coagulation temperature (64° ©.) 
and specific rotatory power («),—-49°. It contains 17-04 nitrogen and 
1:27 sulphur per cent. 

«-Crystallin is more abundant in the outer, 6-crystallin in the inner, 
portions of the lens; the albumin is equally distributed. The lens 
contains no keratin. The proportion between the four proteids in the 
lens as a whole is as follows :— 


Total Proteids. Soluble Proteids. In Fresh Lens. 
[ee eee = 
Albuminoid . . | 48:0 per cent. ad 17:0 per cent. 
a-Crystallin . rile OED) sae 37 per cent. OSs ee 
B-Crystallin . el) 250) tee 62h 4. | el 0) ee 
Albumin ; : 0°5 a 1 7 0:2 ae 


THE MAMMARY GLANDS. 


The chemical constituents of the mammary gland have not been 
much studied. The principal proteid constituent of the cells is nucleo- 
proteid, which swells with dilute alkali, and yields, by boiling with 
mineral acid, a reducing substance. That a reducing substance (sugar) 
can be obtained from the gland was first noted by Bert,! and confirmed 
by Landwehr, who considered its mother substance to be animal-gum ; 
it is considered by Thierfelder*® to be the mother-substance of lactose. 
It is possible that the nucleo-proteid just mentioned may be the precursor 
of caseinogen. The lactalbumin of milk is not identical with serum 
albumin, so that its presence in milk cannot be explained by a simple 
transudation from the blood. 

The extractives of the mammary gland contain not unimportant 
quantities of hypoxanthine ;* they have not been further investigated. 


1 Gaz. hebd. de méd., Paris, 1879, No. 2; Compt. rend. Acad. d. sc., Paris, tome xeviil. 

2 Arch. f. d. ges. Physiol., Bonn, Bd. xl. 8. 21. Thierfelder had previously (ibid., Bd. 
xxxii. S. 619) recognised that the substance is not glycogen. 

3 Loc. cit. 

4+ Hammarsten, ‘‘ Physiol. Chem.,” 8S, 378. 


———— 


MILE. 125 


MILK. 


General properties and composition.—Miulk consists of fluid (milk 
plasma) in which are suspended innumerable minute globules of fat.' It 
is therefore an emulsion, and its white colour is produced, as in other 
emulsions, by reflection from the surface of the numerous globules. 
The specific gravity of cow’s and of human milk is about the same, 
namely, 1028 to 10342 It is increased by the removal of the lightest 
constituent, the cream. Among the milk globules are smaller particles 
of proteid matter (caseinogen or nuclein 7). 3 

The statement is still often made that each fat globule in milk is 
surrounded by a thin membrane of casemogen—the so-called haptogen 
membrane,t and it was considered that it was the rupture of these 
membranes during the process of churning that enabled the fat globules 
to run together to form butter. The evidence on which this idea has 
rested is of a threefold nature :-— 

1. If the milk is filtered through a cell of porous earthenware, the 
filtrate is free, not only from fat, but also from caseiogen. 

2. The mass of milk globules, after having been well washed within 
the filter, gives the reactions for caselogen.° 

3. If ether is added to the milk, without previous addition of 
caustic potash or acetic acid (these were supposed to dissolve or 
break up the proteid envelope), the fat is dissolved out with great 
difficulty. 

But it is now generally held with Quincke,® who made experiments 
with oil and mucilage, that each fat globule by molecular attraction 
is surrounded by a more closely adherent layer of caseinogen solution 
(or rather milk plasma), and not by a membrane. How then can 
one explain the three facts just adduced in favour of the membrane 
theory ? 

1. If milk is filtered through porous earthenware, it is naturally free 
from caseinogen; blood serum filtered in the same way is proteid free. 
The molecules of proteid are too big to go through the pores of the filter ; 
there is no necessity, therefore, to suppose that the casemogen is in a 
solid condition in the milk. 

_ 2. For the same reason, no amount of washing would wash the 
caselnogen through, and so naturally the milk globules would give the 
reactions of the proteid with which they are contaminated. Further, 
Hoppe-Seyler? has shown that cream yields the same percentage of 
casein as the layers of milk below it. 

5. The addition of reagents such as acetic acid (and rennet) enables 
the fat to pass into solution more easily, not because they are solvents 


‘of proteid, for they are not, but because they alter the relations 


between the surface tensions of fat globules and milk plasma, and so 


1 For the measurement and examination of the fat globules, see Fleischmann, ‘‘ Das 
Molkereiwesen,” Braunschweig, 1876-9, S. 206; F. W. Woll, ‘‘ Wisconsin Exper. Stat. 
Agric. Sc.,” 1892, vol. vi. 

* For observations on the specific gravity of human milk, see Monti, Arch. f. Kinderh., 
Stuttgart, Bd. xiii. 

3 Kehrer, Arch. f. Gynack., Berlin, Bd. ii. S.1; D. F. Harris, Proc. Roy. Soc. Edin., 
1896, p. 72. 

een: Arch. f. Anat. u. Physiol., Leipzig, 1840, S. 53. 

> Radenhausen and Danilewsky, Forsch. a. d. Geb. d. V "iehhaltung, Bremen, 1880, Heft 9. 

6 Arch. f. d. ges. Physiol., Bonn, 1879, Bd. xix. S. 129. 

7“ Physiol. Chem.,” S. 728. 


106 THE CHEMISTRY OF THE TISSUES AND ORGANS. 


enable the ether to attack the fat more easily. Moreover, Hoppe-Seyler 
states that it is not so difficult to remove the fat simply with ether; 
the fluid still remains cloudy, it is true, but solutions of casemogen 
are always opalescent, and this is increased by the presence in the 
milk of particles of proteid or proteid-like substances, as described by 
Kehrer. 

The reaction of milk.—Milk readily turns sour from the fermentation 
of lactose and formation of lactic acid. In carnivora fresh milk has an 
acid reaction, but in most animals it gives either an alkaline or, more 
frequently, an amphoteric reaction; the acid phosphates in the milk 
turn neutral litmus red, and the alkaline phosphates turn it blue. The 
proportion between these salts varies very considerably in different 
animals, in the same animal at different stages of lactation, and even 
between the first and last portions of the same milking (Thorner, 
Sebelien,? Courant *). 

Courant estimated the alkaline constituent by titration with 
decinormal sulphuric acid, with blue lackmoid as indicator, and the acid 
constituent with decinormal soda with phenolphthalemm as indicator. 
He found as a mean for the first and last portions of the milking of 
twenty cows, that the alkalinity of 100 c.c. of the milk was equal to 
41 ee, and the acidity equal to 19°5 e.c. of the respective solutions 
used. In human milk the proportional alkalinity is higher; the average 
of the numbers was 10°8 and 3:6 ¢.c. respectively. 

Constituents of milk.—These are water, three proteids (caseimogen, 
lactalbumin, lacto-globulin), two carbohydrates (lactose, animal gum 7), 
fats, extractives (traces of urea, creatine, creatinine, hypoxanthine, 
lecithin, cholesterin, citric acid+), salts and gases. Most of these de- 
mand separate discussion. 

Effect of boiling milk.—When milk is heated to, or near to, the 
boiling point, a scum forms on the surface; on the removal of this skin 
it is rapidly renewed, and this can be repeated over and over again. 
This is probably in part produced by the coagulation of the lact- 
albumin; this carries to the surface some casemogen and fat.? Contact 
with air appears to be the chief influence in causing the solidification 
which results in the formation of the scum; evaporation is rapid from 
the surface exposed to the atmosphere, and thus partial drying occurs 
there. 

The boiling of milk before it is used as a food is advantageous in 
two ways—(1) all micro-organisms are destroyed ; (2) the gastric juice, mn 
virtue of its rennet, causes a flocculent and not a bulky precipitate. 
These quite outweigh any slight diminution of digestibility alleged to 
occur.6 The reason that boiled milk curdles with rennet with greater 


difficulty than fresh milk appears to be that, by boiling, a part of the: 


dissolved calcium salt is precipitated as tricalcium phosphate. 
As milk turns sour, it is possible to get a bulky heat coagulum by 
boiling.” 


1 Chem. Ztg., Cothen, Bd. xvi. S. 1469. 287G1a, Ss DOs 

® Inaug. Diss., Bonn, 1891; and Arch. f. d. ges. Physiol., Bonn, Bd. 1. 

4 Soldner, Zandw. Versuchs. Stat., Berlin, Bd. xxxy. 

® See D. F. Harris, Journ. Anat. and Physiol., London, 1894, vol. xxix. p. 188. 

6 Raudnitz, Ztschr. f. physiol. Chem., Strassburg, Bd. xiv. S. 1. 

7 Recent work on this question will be found in a paper by Cazeneuve and Haddon, 
Compt. rend. Acad. d. sc., Paris, 1895, tome exx. p. 1272. See also influence of boiling on 
the proteids of cows’ milk, Centralbl. i d. med. Wissensch., Berlin, Bd. xxxiv. 8S. 145. 


HUMAN MILK. 1277 


Under the influence of extracts of the pancreas, the caseinogen, 
before it is clotted by the milk-curdling ferment of the gland, passes 
through a stage in which it coagulates by heat. This was termed 
the “ metacasein” reaction by its discoverer, Sir William Roberts.’ It 
does not appear to be due to the simultaneous development of acid 
produced by the fat-splitting ferment of the pancreas, but rather to 
the action of trypsin. Edkins* showed that Kiihne’s purified trypsin 
also produces “metacasein” in an early stage of its action, though it 
does not produce coagulation of milk. 

The composition of milk varies in different animals; human milk 
and cows’ milk are those which have been most investigated. There 
are also variations due to constitution, state of nutrition, and age. 

Human milk.—The mammary glands of new-born animals of both 
sexes often secrete a small quantity of milk for a few days. It is 
popularly termed “witches milk.” tis alkaline.* Analyses by Schloss- 
berger and Hauff,t Gubler and Quevenne,? and Genser,’ show that the 
milk of new-born children contains from 1:05 to 2°8 proteid, 0°82 to 
1-46 fat, 0°9 to 6-4 sugar, and 0°8 salts per cent. 

Colostrum.—This liquid is yellower and more alkaline than fully- 
formed milk. It contains colostrum corpuscles, rather more solids than 
milk, and coagulates on heating. It contains little or no caseinogen, 
but a mixture of lacto-globulin and lactalbumin.’ The globulin is only 
present in traces in fully-formed milk. The following analyses are by 
Clemm,’ with the exception of the last, which is by Tidy.® 


| 
} 


Four Weeks before } } 

i Delivery. Seventeen | Nine Days} Twenty- | Two Days 

Constituents. Days before before | four Hours after | 

aa.) j= Te |) Delivery, tie Delixery: after Delivery. | 

IE. Il. Delivery. 

Water . | 94:52 | 85-2 | 85-17 | 85-85 | 84-38 | 86-79 | 84-08 
Solids. .| 548/148 | 14:83 | 14-15 aie 1321 | 15-92 

Casein : es a wt a af 2-18) | 
Albumin and | 2°88 | 69 | 7-48 | 8-07 |... af ee 

globulin | 
Wale. : 0-71 4°] 3°02 2°35 ath 4°86 | 5-78 
Peinse | 1-73) 3-9) | 37 | Seo) ce) 610 | 651 
Salts . a O44. 0-44 | 0-45 054 | O51 ee tee trad 


1 Proc. Roy. Soc. London, 1879, 1891. 

* Journ. Physiol., Cambridge and London, 1891, vol. xii. p. 203. 

3 Witches’ milk obtained from foals by Ammon (Jahresb. ii. d. Fortschr. d. Thier-Chem., 
Wiesbaden, 1876, S. i118) was acid, but this was probably due to fermentation having set in. 

4 Ann. d. Chem., Leipzig, Bd. xcvi. S. 68. 

> Gaz. méd. de Paris, 1856, p. 15. 

8 Jahrb. f. Kinderh., Leipzig, N. F., Bd. ix. S. 60. 

7 J. Sebelien, Ztschr. f. physiol. Chem., Strassburg, Bd. xili. S. 135. 

8 Wagner’s ‘‘ Handworterbuch d. Physiol,” Bd. ii. S. 464. ; 

9 Lond. Hosp. Rep., 1867-8, p. 77. See also Woodward (Journ. Exper. Med., Baltimore, 
1897, vol. ii. p. 217), for recent analyses of human colostrum. Colostrum corpuscles are 
not constantly present. 


128 THE CHEMISTRY OF THE TISSUES AND ORGANS. 


Normal human milk—The following table gives some of the 
principal analyses that have been published :— 


| | 
| Salts. Remarks. Observers. 


Water. _Case- Albu- Fat. | Sugar. 
inogen.| min. | 
88°58 3°69 3°53| 4:3 | 0°17] 9 days after delivery. !) 
90°58 2°91 3°34] 3:15| 019]12 ,, 55 , |p Clemm. 
86°27 2°95 eal Dolo: Ora2.| > eee eee Tidy. 
86°3 (2°6 Heo || O23 | 
to ;| 1°68 to 3°15 |; to to to pace Biel.! 
sss | \5-4 | 6-6 | 0-34 J 
a 1-28 | 0°34 | 2°56) 5°6 ae | Tolmatscheff.? 
89-1 1°79 353} 5-4 0°42 | Gerber.* 
87°24 1°9 4°3 5-9 0°28 443 Christenn.* 
89°29 1°6 3°2 5:8 0°16 Women 20-30 years old! f,,.. . 
89-06 172 oo | 6:0 | Oe te 30-40° | Ue eeitfer.° ! 
Sian) 253 | eoe9 Be 0°25 | Mendus de Leon.® 
( 1°8 07 | 
be ule ito COM | mace ~ - | ba Makris.7 
\| 4:3 | 1-7) 
97°6 1°52 3°28] 6°50) 0°27) oe Soldner & Camerer.® 
Sern ete? |) 1055.|* 3°30 )| 6:0) | nee} veh Lehmann & Hempel.® 


The most constant feature in these analyses is the relatively low 
percentage of proteids and high percentage of sugar. 

Among other constituents of human milk are, 0°32 per cent. of 
cholesterin (Tolmatscheff), 0°05 of citric acid, and 0-78" of unknown 
extractives; the last are more abundant in the colostrum, and less 
abundant in cows’ milk (Sdldner and Camerer). 

Variations in the composition of the milk occur with the stages of lactation,” 
in the milk from the two breasts and between the first and last portions of 
the milking, with the complexion ' (Vernois and Becquerel—questioned 
by Tolmatscheff), with the age of the individual (Pfeiffer), and with menstrua- 
tion (Vernois and Becquerel). The nature and quality of the food have a 
considerable influence on the quality of the milk.” 


The salts of human milk are thus given by Bunge '* in parts per 1000.— 


A. B. | A. B. 
K,O .. -. 0780 0°703| FeO, «= 0:002niiaae 
NaO . . 0-232. 0257] P.O, &) |. O47aqaiee 
C20...  . 0328- ~0:343 |.Cl..) As |. .0438uate 
MgO .  . 0:064 0-065 | 


1 Jahresb. it. d. Fortschr. d. Thier-Chem., Wiesbaden, 1874, S. 168. 
2 <*Med. Chem. Untersuch.,” Bd. ii. 8S. 272. 


3 Bull. soc. chim., Paris, tome xxiil. 4 Diss., Erlangen, 1877. 
3 Jahrb. f. Kinderh., Leipzig, Bd. xx. 6 Diss., Heidelberg, 1881. 
7 Diss., Strassburg, 1876. 8 Zischr. f. Biol., Miinchen, 1896, Bd. xxxiii. 8. 43. 


9 Arch. f. d. ges. Physiol., Bonn, Bd. lvi. 8. 558. 

10 The presence of citric acid has also been noticed by Scheibe, Landw. Versuchs. Stat., 
Berlin, Bd. xxxix. 

NJ. Munk (Virchow’s Archiv, Bd. cxxxiv. S. 501) gives the proportion of extractive 
nitrogen to total nitrogen as 1:11 in human and 1:16 in cows’ milk. 

12 Pfeiffer, Zoc. cit.; Vernois and Becquerel, Compt. rend. Acad. d. sc,, Paris, tome xxxvi. 

. 188. 
: 18 Sourdat, ibid., tome Ixxi.; Brummer, Arch. f. d. ges. Physiol., Bown, Bd. vii. 

14 )’Heritier, ‘‘Traité de chim. pathol.,” Paris, 1842. 

15 Decaisne, Gaz. méd. de Paris, 1871, p. 317. These are very interesting observations 
made during the siege of Paris. Other work on the influence of food on milk is that by 
Szubotin, Centralbl. f. d. med. Wissensch., Berlin, 1866, S. 337, and by Commaille, quoted 
by Konig, ‘‘ Chem. d. menschl. Nihrungs. u. Genussmittel,” Bd. ii. S. 235. The question 
of the influence of diseases and drugs will be found discussed in works on Therapeutics 
and Pathology. 16 Zischr. f. Biol., Miinchen, Bd. x. 


COWS? MILK. 129 


The gases of human milk.—In five experiments, L100 cc. of milk 
yielded 1:07 to 1:44 c.c. of oxygen, 2°35 to 2°87 c.c. of carbonic anhydride, 
and 3°37 and 3°81 ¢.c. of nitrogen. The method of collecting the milk 
could not have obviated admixture with small quantities of air; hence, 
no doubt, the higher percentage of oxygen and nitrogen than previous 
observers have found in the milk of lower animals." 

Cows’ milk.—Colostrwm.—This has a high specific gravity (1046- 
1080). Its fat hasa higher melting point than that of normal milk, 
being poorer in the lower fatty acids.2 It contains more lecithin, 
cholesterin, and proteid coagulable by heat than normal milk.? The 
following are some analyses that have been made :— 


; Seti Vaudin.6 : Vaudin.6 
Fleischmann.# Konig. Just after delivery. Bars soma 

Water 78°7 14:7 Tyee 85°63 
Solids Dis 25°3 DD A974 14°37 
Casein ; 5 : {<3} 4°04) ’ 4 ae 
Albumin and globulin “Ala 13°6. f Meek eh ie 
Fat : 4-0 3°6 2°42-6°3 5°18 
Lactose 1°5 Di 1°02-2°86 4:07 
Salts . 1:0 1°6 111-2 0°16 


Normal cows’ mill.—The followmg are averages of numerous 
analyses, in the first column of those collected by Gorup-Besanez,’ in the 
second, by Hoppe-Seyler.s 


I Il. 
Water 84:28 85-86 
Solids 15°72 15-18 
Caseinogen . : ; 3°57 3-4 
Albumin 0-75 0:3—-0°5 
Fat é : ! : 6°47 4 
Lactose . ; 3 : 4°34 4°5—5 
SaltSi pes: F ; : 0°63 


Hammarsten® gives the following tables (from Konig) of normal 
milk and the averages of various preparations from milk as follows :— 


Milk. Skimmed Milk. Cream. Butter Milk. Whey. 
Water SOL 90°66 65°51 90°27 93°24 
Solids 12°83 9°34 34°49 9°73 6'76 
Caseinogen . 3°02) : ; i “gr 
iltanviin 0°53 3°11 3°61 4°06 0°85 
Fat 3°69 0°74 26°75 0°93 0°23 
Sugar. 4°88 4°75 3°52 . 373 4°7 
Salts . F 0-71 0°74 0°61 0°67 0°65 
Lactic acid. : a3 se sah 0°34 0°33 

| 


Tatlock !° gives the average composition of skimmed milk as.follows—(1) 


1K. Kiilz, Ztschr. f. Biol., Miinchen, 1895, Bd. xxxii. S. 180. 
2 Nilson, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, Bd. xvii. 8S. 169. 
3 Toid., Bd. xviii. S. 102. 


4 ** Das Molkereiwesen,” S. 39. > Chem. d. Mensch. Nihrungsmittel.” 
6 Journ. de pharm. et chim., Paris, 1894, Sér. 5, tome xxx. p. 337. 
7 “*Tehrbuch,” 1878, S. 424. 8 «* Physiol. Chem.” 


® «Physiol. Chem.,” 3rd German edition, S. 388, 390. : 
W “Produce of the Dairy,” Glasgow, 1888. Numerous milk analyses will be found in 
this book. 


VOL. I.—9 


130 THE CHEMISTRY OF THE TISSUES AND ORGANS. 


By repose and skimming—fat, 1; proteid, 3°44; lactose, 5-1; ash, 0°75; 
water, 89°67. (2) By separator—fat, 0-2; proteids, 3°4; lactose, 5°01; ash, 
0°75; and water, 90°64. 

The presence of citric acid in milk was first shown by Soxhlet. Vaudin? 
considers that this is not from the food, but produced in the mammary gland. 

The variations in the milk with feeding, species of animal, time of day, 
etc., are described by Struckmann and Bodeker,? Fleischmann,’ Tatlock,? 
Kiihne and Fleischer,* and others. 


Salts of cows’ milk.—Soldner® gives the following percentages :— 


KO": j : : : : : 0-172 
Na,O : 3 ; : ; , 0-051 
CaO . : : : ; ‘ 07198 
MgO. : : : ‘ 0:020 
P.O, (after correction for pseudo-nuclein) 0°182 
Ol ee 0-098 


Of the total phosphoric acid, from 36 to 56 per cent., and of the lime from 
53 to 72 per cent., is not simply dissolved in the fluid, but is united more or 
less firmly to the caseinogen. The excess of bases over mineral acids is united 
to organic acids, such as citric. Bunge found 0:00035 per cent. of iron. 


The gases of cows’ milk have been analysed by Setchenow® and Pfiiiger.’ 
There are small quantities of oxygen and nitrogen, and from 5 to 10 per 
cent. of carbonic anhydride. 

In comparing the composition of cows’ milk with that of human milk, 
the main difference consists in the high percentage of proteids, fats, and 
salts, and the low percentage of sugar in cows’ milk as compared with 
human milk. Qualitative differences will be noted under the headings 
“ Proteids” and “ Fats.” 

The milk of other animals.—Some of the principal analyses are 
collected into the following table :-— 


| 
Reference 


Animal. Water. | Caseinogen. | Albumin. Fat. Lactose. Salts. to Notes 
| below. 

Dog. 75°4 9°91 9°57 3°19 0°73 8 
Cat é , 81°6 9-08 3°33 4°91 0°58 8 
Goat. elle CORO 3°69 4:09 4°45 0°86 9 
Goat. : So) | eines: 3°64 5:35 3°60 0°66 10 
Sheep | 83°5 5°74 6°14 3°96 0°66 il 
Sheep 82-84 4°7 4-8 3-4°6 | 0°6 | 12 

1 Journ. de pharm. et chim., Paris, tome xxx, p. 464. 

2 Ann. d. Chem., Leipzig, Bd. xevii. S. 150. 3 Lae, tt. 

4 Landw. Versuchs. Stat., Berlin, Bd. xii. S. 405. > Loc. cit. 


6 Zischr. f. rat. Med., Bd. x. S. 285. 

7 Arch. f. d. ges. Physiol., Bonn, Bd. ii. S. 166. 

8 Taken from Kénig’s analyses. The milk is acid, rich in proteids and calcium. The 
lactose is increased by starchy, and lessened though not abolished by a flesh diet (Bensch, 
Ann. d. Chem., Leipzig, Bd. lxi. S. 221; Poggiale, Gaz. méd. de Paris, Sé. 3, 
tome x. p. 259). See also Simon, ‘‘Die Frauenmilch,” Berlin, 1838; Dumas, Compi. 
rend. Acad. d. sc., Paris, tome xxi. p. 707 ; Kemmerich, Centralbi. f. d. med. Wissensch., 
Berlin, 1866, No. 30; Szubotin, zbid., No. 22. 

® Taken from Konig. 

10 From Pizzi’s analyses (Staz. Sper. Agrav., 1894, Bd. xxvi. S. 615; Abstract in Journ. 
Chem. Soc., London, 1896, vol. ii. p. 120). Goats’ milk differs from cows’ milk in smell 
and taste, and in containing more insoluble volatile fatty acids. In reindeer’s milk these 
acids are less abundant (Solberg, Centralbl. f. agric. Chem., Leipzig, 1896, S. 15). 

From Konig. 

2 From Vernois and Becquerel, Union méd., Paris, 1867, p. 78. 


THE MILK OF OTHER ANIMALS. 13% 


The milk of other animals—continued. 


Reference 

Animal. Water. | Caseinogen. | Albumin, Fat. | Lactose. | Salts. to Notes 

| below. 

‘eae 

Sheep : : 80°42 | 4:44 9°66 4-4 isi 1 
Mare ‘ , 90°06 1°89 1:09 6°65 0°31 2 
$ : ‘ 90 1°8 0°3 1°3 Bebe i NOpe 3 
"5 ‘ : 92°5 1°3 | 0°3 0°6 4°7 0°3 4 
sp : : 91-0 1°05 1°3 Bi 0°3 5 
ASS: : : 90:0 2°1 1°3 6°3 0°3 6 
eee, 1), 90°5 ig! Tae! 6°40 7 
Ass . ; : 89-0 3°5 1°8 a0) 0°5 8 
feemeaeae ). |? 82°37 6-09 6-4 4°04 1:06 9 
Rig: : 3 83:0 7°0 C0) 1) 1°05 10 
Biss. : q 81°8 53 6:00) [16:0 0:08 10 
Mule. : : 89°3 2°6 1°9 6°03 0°53 idl 
Hippopotamus . 90:0 | Be 45 3; 0-1 12 
Camel - : 86°3 BeLi 29 58 0°6 13 
Elephant . : 67°85 3°09 1°95 8°84 0°65 14 
Dolphin . ; 48°67 | - ae 43°76 ae 0°46 15 
Dalialoys):\\%1.| 82°20 | 413 BOD 4 4575 0°97 16 
Rabbit. { 69°50 15°54 10°4 USE 2°56 17 


Salts of dogs’ and mares’ milk.—These may be compared in the 
following table of Bunge’s '8 with those we have already studied :— 


HUMAN. Doe. 
Cow. Mare. 
I II Le II 

K,O 0°78 Of sal 1°68 1:76 1:04 
Na,O 0°23 0°26 | 0°80 0°69 nSilal 0°14 
CaO 0°33 0:34 | 4:53 4°28 59 S75} 
MgO 0°06 0706 | 0°19 0°21 0°21 0°12 
Fe,0, 0°003 0:006 | 0:02 0°01 0°003 0°015 
POR 0°47 0°47 4°93 4°67 1:97 1°31 
C1. . iz 3 0°43 0°44 1°62 1°8 1°69 0°31 
Total ash per 1000 . Pp? 2°18 Shey 12°96 7°97 4°17, 


1 From Pizzi. Sheep’s milk contains a high percentage of fat. 

2 From Konig. 

° From Biel, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1864, 8. 171. 

4 From Soxhlet, zbid., 1878, S. 152. 

5 From Weiske and Schrodt, bid., 1878, S.151. The caseinogen of mares’ milk is more 
like that of human than of cows’ milk. This is the milk originally used in the preparation 
of koumiss and similar fermented liquors in Russia. 

6 From Konig. 

7 From Gubler and Quevenne, Gmelin’s ‘‘ Handbuch,” Bd. viii. S. 267. 

8 From Vernois and Becquerel. Asses’ milk is much used by invalids. 

® From Konig. 

10 From Leutner, in Gorup-Besanez, ‘‘ Lehrbuch,” S. 424. 

1 From Aubert and Colby, Chem. News, London, vol. lxviii. p. 168. 

2 From Chem. Centr.-Bi., Leipzig, 1871, 8. 149. 

18 From Dragendorf, ibid., 1867, S. 78. See also Vernois and Becquerel for analyses of 
camels’ milk. 

4 From Konig. 

% From Frankland, Chem. News, London, 1890, vol. lxi. Note the enormous percentage 
of fat. 

16 From Pizzi. For buffaloes’ milk, see also Pappel and Richmond, Journ. Chem. Soc., 
London, 1894, p. 754. : 

@ From Pizzi. 

18 Diss., Dorpat., 1874 ; Zischr. f. physiol. Chem., Strassburg, Bd. xiii. S. 399. 


132 THE CHEMISTRY OF THE TISSUES AND ORGAWS. 


The chief acid present throughout is phosphoric acid; the chief base 
in human milk is potash; but this in most other mamials is second to 
lime ; in dogs’ milk the lime is especially high. 

In connection with the iron in the milk it is to be noticed, that 
although the other mineral constituents of the milk are present in the 
propor ‘tion in which they are contained in the foetal tissues, the quantity 
of iron in milk is less. 


One hundred parts by weight of ash contain— 


In New-born Dog. In Dogs’ Milk, 
K,O . , 11:42 : : 14:98 
Na,O ‘ . 10°64 : : 8°80 
CaO » op | 2958) eee 
MgO : , 1°82 ; : 154 
Fe,0, : : 0:72 : 4 0-12 
iPS O, . : 39°42 : : 34°22 
Cl ; : : 8°35 : ; 16°90 


The slightly different proportion in soda and potash is easily ex- 
plained by the fact that in the young ammal the potash-rich muscle is 
increasing, and the soda-rich cartilage is diminishing. The high per- 
centage of chlorine in the milk is also explicable, on the hypothesis that 
the chlorides serve not only to build up tissues, but also largely as 
solvents in removing waste products. But the percentage of iron 
in the milk is only one-sixth of that in the foetal tissues. The foetus 
obtains its supply of iron before birth through the placenta, and stores 
it in the liver (see p. 86). As the young animal grows, a kilogram of 
body weight contains less and less iron. 

Iron appears to pass to the offspring through the placenta rather 
than by the milk, because of the difficulties of absorbing iron by the 
alimentary canal, and the danger that hematogenous (ze. nuclein) 
compounds may there become the prey of bacteria. Bunge further 
regards it as probable that the large amount of iron which passes to the 
foetus is not all derived from the mother’s food during the relatively 
short period of pregnancy, but that a storage of iron occurs in the 
maternal organs even before the first conception ; and this may explain 
the occurrence of chlorosis at the age of puberty. 

The carbohydrates of milk.—The most important carbohydrate 
in milk is lactose, or milk-sugar, the properties of which are described 
on page 12. It is found in varying quantities in the milk of all 
animals; the only exception to this rule hitherto noted is that of 
the Egyptian buffalo (Los bubalus), where it is replaced by another 
sugar christened tewfikose' by Pappel and Richmond;? it yields dex- 
trose only on hydrolysis. 

Though lactose is not fermented by yeast, yet it undergoes the 
alcoholic fermentation under the influence of other schizomycetes, as 
in the preparation of koumiss and kephir. 


Ritthausen * found in milk another carbohydrate which is soluble in water, 
and is not crystallisable ; its reducing power is low, and increased after boiling 


1 After the Khedive of Egypt. 
2 Journ. Chem. Soc., London, 1894, p. 754. 
3 Journ. f. prakt. Chem. , Leipzig, N. Epo BG Ve 


THE FATS OF MILK. £33 


with acid. Landwehr! identified it as animal gum, Béchamp? as dextrin. 
J. Herz* found granules in milk, which behave towards iodine like starch ; 
he called them “animal amyloid.” 


The fats of milk.—Milk fat has a specific gravity of from 949 
to 996.* It consists of palmitin, stearin, and olein, with small quantities 
of triglycerides of butyric, caproic, caprylic, capric, myristic, and arachie 
acids in addition.® It also contains small quantities of lecithin, choles- 
terin, and a yellow lipochrome. 

The amount of fat in cream varies from 14 to 44 per cent. In butter, 
besides fat, there are small quantities of caseinogen and lactose. The 
fats of cows’ butter consist of 68 per cent. of palmitin and stearin, 30 
per cent. of olein, and 2 per cent. of the specific butter fats. Their 
melting point is 51° to 54°C. The volatile fatty acids in cows’ milk, accord- 
ing to Duclaux, amount to 7 per cent., of which 3°7 to 5-1 is buty ric, and 
2-0 to 33 is caproic acid. Some analysts give still higher percentages. 

By exposure to the air butter becomes rancid; this is partly due to 
the production of lower fatty acids from the higher fats (see p. 19), 
partly to the formation of acrolein from glycerine, and partly, and 
according to Hagemann chiefly, to the formation of lactic acid from the 
entangled lactose. 


The composition of butter is very variable. Thus, in Finland butter, 
Koefoed* found two fatty acids of the acrylic series in addition to oleic 
acid; 100 parts of the fatty acid contained 66 of these acids, 28 of 
palmitic, 22 of myristic, 8 of lauric, 1-5 of butyric, 2 of caproic, 2 of capric, 
and 0°5 of caprylic acid. According to Wanklyn,° there is no true palmitic 
acid in butter ; the acid is aldepalmitic acid (C,,H,,0,). 


The fats of human milk are somewhat different from those of cows’ 
milk. They have been the subject of two recent researches—one by 
Ruppel,” the other by Laves." 

Their melting point is 34° C., and solidifying point 20°-2 C. Their 
specific gravity at 15° C. is 966. The fatty acids found are butyric, 
caproic, capric, myristic, palmitic, stearic, and oleic acids, all combined 
with glycerine. The presence of formic acid !2 is also inferred from its 
reducing action, but not by any further tests. Human milk is poor in 
volatile acids (Ruppel). 

Laves confirms this work, and gives some quantitative results. The 
fat contains 1-4 per cent. of volatile acids, 1-9 of acids soluble in water, 
and 49-4 (a very high percentage) of unsaturated acids. The volatile 


1 Arch. f. d. ges. Physiol., Bonn, Bde. xxxix. and xl. 

2 Bull. Soc. chim., Paris, Sér. 3, tome vi. 

3 Chem. Ztg., Cothen, Bd. xvi. S. 1594. 

4 Bohr, Jahresb. it. d. Fortschr. d. Thier-Chem., Wiesbaden, Bd. x. S. 182. 

> Grunzweig, Ann. d. Chem., Leipzig, Bd. clxii. S. 215; E. Wein, Diss., Erlangen, 
1876; Chevreul, ‘‘ Recherches sur le corps gras,” Paris, 1823 ; Lerch, Ann. d. Chem., 
Leipzig, Bad. xlix. S. 212; Heintz, zbid., Bd. lxxxyiii. S. 300. 

® Bromeis, ibid., 1842, Bd. xiii. S. 46. 

7 Compt. rend. Acad. d. sc., Paris, tome civ. 

8 Overs. 0. d. k. Danske Vidensk. Selsk. Forh., Kjobenhavn, 1891. 

° Chem. News, London, vol. 1xiii. 

Y Ztschr. f. Biol., Miinchen, Bd. xxxi. S. 1. 

Ut Zischr. f. physiol. Chem., ‘Strassburg, Bd. xix. S. 369. 

2 Duclaux (loc. cit.) found formic acid in cows’ butter which had bach exposed to 
sunlight. 


134 THE CHEMISTRY OF THE TISSUES AND ORGANS. 


acids contain equal quantities of caproic, caprylic, and capric acids, and 
the merest traces of butyric acid. The principal acids present, as is 
usual in animal fat, are palmitic, stearic, and oleic acids, and one or 
more acids of lower molecular weight, including myristic acid. The 
melting point of the mixture of acids is 37° to 39° , and of the fat itself 
50 reroll: MC: 

The proteids of milk.—-The proteids which occur in milk are 
three in number. The most abundant and most important of these is 
caseinogen. It is this proteid which is acted upon by rennet, and 
converted into casein or cheese.1 The other two proteids are only 
present in small quantities; they are called lactoglobulin and _ lact- 
albumin. Proteoses and peptone were described in milk by many of 
the older workers. This was due to the use of faulty methods of 
analysis (see p. 41).? 

Coagulation of milk.—When milk is allowed to stand at the 
ordinary temperature exposed to the air, the chief change it undergoes 
is the lactic acid fermentation. The acid formed precipitates a part of 
the caseinogen, but this is a different thimg from the conversion of 
caselmogen into casein. Sometimes, however, certain aérobie bacterial 
growths act like rennet in causing a true curd. Certain of the higher 
plants (Ficus, ete.) also curdle milk. 

The agency by which the clot is most readily formed is that of 
rennet. This isa ferment secreted by the stomach, and is usually obtained 
from the stomach of sucking animals, like the calf. The pancreatic 
juice also has a curdling action on milk (see p. 137), and extracts of 
many tissues (such as testis, liver, lung, muscle) have a feeble action of 
the same nature.* 

Hammarsten* and, later, Friedberg® showed conclusively that the 
active principle of rennet is not pepsin; that it requires for its efficient 
action the presence of calcium salts, of which the phosphate is the one 
which is mostly present in the milk, and that it will act in a weakly 
acid, neutral, or alkaline solution. It acts most readily at 40° C., and 
is destroyed at 70° C. The ferment itself in the rennet extracts is 
termed chymosin by Friedberg, and rennin by Foster.® 

When rennet is added to cows’ milk the result is a coherent clot or 
curd, which expresses a clear yellowish fluid, the whey. The curd 
contains the fat entangled with the casein; the whey contains the other 
proteids, sugar, and salts of the milk. In human milk the curd is 
usually composed of smaller floceuli, and a similar flocculent coagulation 
can be produced in cows’ milk by previously boiling it, or by diluting it. 
Lime water, soda water, or barley water are generally used as diluents 
for this purpose. 

The coagulation of milk is somewhat analogous to that of blood, 
and the analogy is accentuated by the fact that in both cases caleium 


1 The utility of this nomenclature is at once apparent when casein and caseinogen are 
contrasted with fibrin and fibrinogen, myosin and myosinogen, even although the analogy 
is not complete in details. Hammarsten, however, prefers to call the proteid in milk, 
casein; while the coagulated proteid he terms, after Schulze and Réose (Landw. 
Versuchs. Stat., Berlin, Bd. xxxi.), paracasein. 

2 Fora critical article on the estimation of the various proteids in milk, see Schie 
Ztschr. f. physiol. Chem., Strassburg, 1896, Bd. xxii. S. 197. 

3 Edmunds, Journ. Physiol., Cambridge and London, 1896, vol. xix. p. 465, 

4 Jahresb. ii. d. Fortschr. d. Thier- Chem., W iesbaden, 1874, S, 135, 

5 Journ. Am. Chem. Soc., N. Y., 1888, D. aly 

8 «°Text-book,” 5th edition, p- 519, 


bad 


— 


THE PROTEIDS OF MILK. 135 


salts appear necessary, and that coagulation can be delayed or prevented 
by decalcifying the fluid. This is most readily done by adding a small 
quantity of a soluble oxalate. Peptone has, as with blood, a retarding 
effect on coagulation.” 

Green* has suggested that there is a definite relationship between 
the ferment and the calcium salt, resembling that which exists between 
pepsin and hydrochloric acid. Hammarsten * and, later, Ringer® showed 
what this relationship is. The formation of casein from caseinogen is, in 
fact, a double process: the first action is that of the ferment which 
converts the caseinogen into what we may call “soluble casein”; the 
second action is that of the calcium salt which precipitates the casein 
as curd, which is probably caseate of lime. This may be shown by 
taking a solution of caseinogen and adding rennet; if the mixture is 
warmed to 40° C., no visible change occurs; but nevertheless soluble 
casein, and not caseinogen, is now present. If the mixture is now boiled 
to destroy the ferment, cooled, and a drop of 2 per cent. calcium chloride 
added, the formation of a curd takes place. 

Casein and caseinogen differ in several of their properties. The 
curd of caseinogen precipitated by acetic acid is not nearly so coherent 
as the curd of casein produced by rennet. The precipitability of 
caseinogen by acid is not prevented by the addition of an oxalate, 
and there is 13 per cent. more calcium phosphate used up in rennet 
coagulation than in acid precipitation.’ 

The action of rennin upon caseinogen is not a simple conversion of 
that proteid into one of a more insoluble kind; but just as the fibrin 
ferment splits the molecule of fibrinogen into an insoluble proteid, fibrin, 
and a soluble globulin which passes into the serum, so rennin splits 
the caseinogen molecule into two parts: one part is the curd or casein; 
the other is a soluble proteid which passes into the whey, and is termed 
“whey proteid” by Hammarsten. This is the equivalent of the lacto- 
protein of other investigators. Some of these state it is like a proteose 
or peptone. It is certainly not coagulated by heat; it is precipitable by 
saturating with magnesium sulphate; rennet has no further action on 
it. It does not, however, give the pink biuret reaction. It contains 
C., 50°3; and N., 13-2 per cent.? 

Caseinogen.—This proteid may be precipitated from milk by the 
addition of acids like acetic, or by saturation with salts like sodium 
chloride and magnesium sulphate, or by half-saturation with ammonium 
sulphate. In all cases the fat of the milk is entangled with the 
precipitate. Caseinogen may be most readily prepared free from fat 
by first half-saturating the milk with ammonium sulphate; the precipi- 
tate is collected, well washed with half-saturated solution of the same 

1 Arthur and Pages, Arch. de physiol. norm. et path., Paris, Sér. 5, tome ii.; Compt. 
rend. Soc. de biol., Paris, tome xliii, The addition of oxalates does not absolutely decalcify 
blood or milk ; the calcium in close combination with the proteid remains uuprecipitated. 
See Schafer (Proc. Physiol. Soc., 1895, p. xviii); Hammarsten (Zischr. f. physiol. Chem., 
Strassburg, 1896, Bd. xxii. S. 333), and also the article in this book on Blood. 

* Edmunds, loc. cit. 3 Journ. Physiol., Cambridge and London, vol. viii. p. 371. 

4 *< Zur Kenntniss des Kaseins,” Nova Acta Reg. Soc. Scient., Upsala, 1877. Festschrift. 

® Journ. Physiol., Cambridge and London, vol. xi. p. 464. 

6 Here the analogy of casein and fibrin breaks down. In blood coagulation the cal- 
cium salts assist in the génesis of the fibrin ferment rather than in the formation of 
fibrin from fibrinogen (Hammarsten, /oc. cit.) ; 

7D. F. Harris, Journ. Anat. and Physiol., London, 1894, vol. xxix. p. 188. 


8 Halliburton, Journ. Physiol., Cambridge and London, vol. xi. p. 462. 
® Koster, Jahresb. it. d. Fortschr. d. Thier-Chem., Bd. xi. S. 14. 


136 THE CHEMISTRY OF THE TISSUES AND ORGANS. 


salt, and then distilled water is added. This, in virtue of the salt adhering 
to the precipitate, dissolves out the caseinogen, and carries it through 
the filter, the greater part of the fat being left behind. From this 
solution the casemogen is precipitated by acetic acid; it is collected, 
thoroughly washed, and dissolved in. dilute alkali like lime water, and 
purified by repeated precipitation with acid and re-solution in alkali. 

Ringer’s method of obtaining casemogen is a slight modification of 
that of Hammarsten: he precipitates caseinogen with acetic acid, collects 
and washes the precipitate, and grinds it up in a mortar with calcium 
carbonate; the mixture is thrown into excess of distilled water; the fat 
rises to the top; the chalk falls to the bottom, and the intermediate 
opalescent fluid is a solution of casemogen. The separation into the 
three layers may be hastened by the use of the centrifuge. 

In both cases, the caseinogen, if it has been thoroughly washed from 
soluble calcium salts, will not clot with rennet; the lime water in the one 
case and the calcium carbonate in the other not being sufficient to 
cause the separation of the curd: this, however, occurs immediately on 
the addition of a soluble salt of lime like the phosphate or chloride. 

Solutions of caseinogen are not coagulated by heat. By prolonged 
heating they become opalescent; this often disappears on cooling. In 
some cases a scum forms on the surface, as in milk. 

Caseimogen is not a globulin; still less is it an alkali albumin: it is 
a nucleo-albumin. 

Analyses by Chittenden? gave the following result —C, 53°3 ; H, 7-07; 
N, 15°91; 8,082; O, 22:04. The amount of phosphorus was not 
estimated. Danilewsky? considered it to be a mixture of two proteids, 
but this, as Hammarsten * showed, was due to faulty methods of prepara- 
tion. Chittenden made a study of the caseoses and proteoses obtainable 
from it by digestion. Sebelien,> who also prepared casein peptone, 
states it is optically inactive—a most exceptional occurrence among pro- 
teids. The most interesting fact about its digestion by gastric juice, 
however, is, that it yields a precipitate of nuclein, or rather of pseudo- 
nuclein © (see pp. 65, 66). 

The amount of and varieties of calcium phosphate in union with 
caseinogen and casein has been investigated by Soxhlet and Séldner? 
and by Courant.§ Sdéldner describes two caleium compounds of 
caseinogen, containing respectively 1:55 and 2°36 per cent. of CaO; these 
are called dicalcium casein and tricalcium casein. Moraczewski ® finds 
that the yield of pseudo-nuclein varies from 1:3 to 21:1 per cent. 
of the caseinogen employed; he finds that the amount of phos- 
phorus in the pseudo-nuclein varies from 0°88 to 6°86 per cent. The 
whole phosphorus of the casein is not in the nuclein; the quantity 
in the nuclein is given as from 6 to 60 per cent. of the whole. This has 
been confirmed by Salkowski and Hahn.!° These observers also find that 


1 Stud. Lab. Physiol. Chem., New Haven, vol. ii. p. 156); 11. p. 66: 

® Zischr. f. physiol. Chem., Strassburg, Bd. vii. S. 433. 

8 Tbid., Bd. vii. S. 227. 

+ On peptonised milk see also Horton-Smith, Journ. Physiol., Cambridge and London, 
1891, vol. xii. p. 42. 

° Centralbl. f. agric. Chem., Leipzig, 1889, S. 717. 

§ Moraczewski, Zischr. f. physiol. Chem., Strassburg, Bd. xx. 

7 Loc. cit. Celica cits 

* Ztschr. f. physiol. Chem., Strassburg, 1894, Bd. xx. S. 28. 

1° Arch. f. d. ges. Physiol., Bonn, Bad. lix. 


THE PROTEIDS OF MILK. 137 


the pseudo-nuclein is partly soluble in gastric juice;1 it is by far the 
most soluble of the nucleins? though the majority are partly soluble 
after pancreatic digestion.® 

Casein.—This name should be restricted to the proteid formed by 
the action of rennin, or of ferments that act like rennin. As a general 
rule, it is more insoluble than caseinogen ; it is, however, readily soluble 
in dilute alkalis such as lime water. From these solutions it is readily 
precipitable by traces of calcium chloride; and also by sodium chloride 
(Hammarsten). The precipitate with calcium chloride increases on 
heating, but, like many calcium compounds, partially redissolves on 
cooling (Ringer). 

The main distinction between casein and caseinogen is, however, 
that which was first insisted on by Hammarsten, namely, that caseinogen 
can be curdled by rennet, casein cannot. Some recent work by D. F. 
Harris ‘+ and Peters ® appeared to cast doubt upon this essential distinction, 
and to suggest the possibility of recoagulation of casein, analogous to 
that of myosin. The fallacies into which these observers were drawn 
have been pointed out independently by Edmunds, Hammarsten,’ and 
R. Benjamin.’ Peters, for instance, used a preparation of rennet, rich in 
sodium chloride and calcium salts; the precipitate he obtained by adding 
this to a solution of casein was due to these salts, not to the ferment. 

Panereatie casein.—An interesting variety of casein is that formed 
by the action of pancreatic juice on milk, which has been recently 
investigated by Brodie and myself.® 

Kiihne!” was the first to point out that extracts made from the 
pancreas of the dog cause milk to coagulate; this action was described 
in some detail by Sir William Roberts! Various conditions which 
influence the clotting were observed by Edkins, and the occurrence of 
the action in pancreatic extracts from a number of animals determined by 
Harris and Gow.'* 

Our attention was drawn to the subject by a sentence in Prof. 
Gamgee’s “ Physiological Chemistry,” in which he points out that it does 
not necessarily follow that because extracts of the organ have a clotting 
action, the pancreatic juice possesses it also. 

We accordingly performed experiments with the actual pancreatic 
secretion, obtained from temporary fistulee in dogs, and our conclusions 
are summarised as follows :— 

1. The pancreatic juice obtained from temporary pancreatic fistule, 
from dogs, produces a change in the casemogen of milk. 


1 The nutritive value of casein is given by Marcuse (Arch. f. d. ges. Physiol., Bonn, Bd. 
lxii. S. 223) as equal to that of meat proteids. 

2B. Salkowski (Virchow’s Archiv, Bd. exliv.) states that caseinogen, if not coagulated in 
the process of preparation, is completely digested by gastric juice, if a sufficient volume of 
the latter is employed, e.g. 500 parts of gastric juice to 1 of caseinogen. 

3 Sebelien, Zischr. f. physiol. Chem., Strassburg, Bd. xx. ; Popoff, ibid., Bd. xviii. ; 
Gumlich, ibid., Bd. xviii. ; Weintrand, Verhandl. d. physiol. Gesellsch., Arch. f. physiol., 
Berlin, 1895; Clara Willdenow, Inaug. Diss., Bern, 1893; W. Sandmeyer, Zéschr. f. 
physiol. Chem., Strassburg, 1895, Bd. xxi. S. 87. = OCC 

> Preisschrift, Rostock, 1894. § Loe. cit. 

7 Ztschr. f. physiol. Chem., Strassburg, 1896, Bd. xxii. S. 103. 

8 Virchow’s Archiv, 1896, Bd. exlv. 8. 30. 

9 Journ. Physiol., Cambridge and London, 1896, vol. xx. S. 97. 

W Verhandl. d. naturh.-med. Ver. zw Heidelberg, N. ¥., Bad. iii. S. 3. - 

U Proc. Roy. Soc. London, 1879 and 1881. 

2 Journ. Physiol., Cambridge and London, 1891, vol. xii. p. 193. 

13 Tbid., 1892, vol. xiii. p. 469. 4 Vol. ii. p. 446. 


138 THE CHEMISTRY OF THE TISSUES AND ORGANS. 
2. This action differs from the action of rennet in the following 
particulars :— 

(a) The precipitate of casein occurs in the warm bath (35°—40° C.) 
in the form of a finely granular precipitate, the milk to the naked eye 
undergoing no change in its fluidity. On cooling this to the temperature 
of the air, it sets into a coherent curd which contracts to only a small 
extent, and is again broken up into fine granules by warming to 35° C., 
‘the milk to the naked eye becoming again fluid. This may be repeated 
a great number of times. 

(b) This phenomenon is not prevented, but only slightly hindered, by 
such an addition of potassium oxalate as completely inhibits the activity 
of rennet. 

3. The experiments performed with extracts of the gland lead to 
similar results, which may be masked if the action of the tryptic ferment 
is very energetic. 

4. The precipitate produced may be provisionally termed pancreatic 
casein. By the action of rennet it can be converted into true casein. 
Its solubilities, as summarised in the following table, are partly like 
those of caseinogen, partly like those of casein. It is probably some- 
thing intermediate between the two. 


(a) Caseinogen. (b) Casein. (c) Pancreatic Casein. 
(az) In water + CaCO,| Soluble. Insoluble. Insoluble. 
(6) In lime water Soluble ; precipitable | Soluble ; precipitable | Soluble ; precipitable 
with difficulty by | witheasebyCaCl,;} with ease by CaCl, ; 
CaCl,. precipitate pro- | precipitate pro- 


(c) The precipitate 
produced by add- 
ing CaCl, to (b) 

(d) Lime water solu- 
tion. 


(e) In 0°5 sodium 
bicarbonate solu- 
tion. 


Soluble in 5 per cent. 
NaCl. . 


Converted into casein 
by trace of phos- 
phoric acid and 
rennet. 


Soluble ; precipitable 
with ease by CaCl, ; 
precipitate pro- 
duced by trace of 
CaCl, at 40°, dis- | 
solves on cooling. 


duced by trace of 
CaCl, at 40°, soluble 
on cooling. 

Insoluble in 5 per 
cent. NaCl. 


Soreadily precipitable 
by trace of calcium 
salts that theaction 
of rennet could not 
be properly tested. 

Soluble ; precipitable 
with difficulty by 
CaCl,. 


duced by trace of 
CaCl, at 40°, not 
soluble on cooling. 
Slightly soluble in 5 
per cent. NaCl. 


Behaves like casein- 
ogen, 


Soluble ; precipitable 
with ease by CaCl, ; 
precipitate —_ pro- 
duced by trace of 
CaCl, at 40°C., not 
soluble on cooling. 


The casein and caseinogen of human milk.—The facts described up 
to the present point are derived from experiments on cows milk. 
There are very important differences between this and the principal 
proteid of human milk. A large number of investigators! have noted 
such differences as a more finely subdivided and more easily digestible 
clot formed by rennet, but the difference between the two proteids goes 
deeper than that. Human caseinogen is more difficult to precipitate by 
acids (and is easily soluble in excess) and by salts; it often will not 


1 Bredert and Schroter, Centralbl. f. agric. Chem., Leipzig, 1888; Biedert, ‘‘ Untersuch. 
ii. d. chem. Unterschiede der Menschen und Kuhmilch,” Stuttgart, 1884; Langgaard, 
Virchow’s Archiv, Bd. lxv. ; Makris, Inaug. Diss., Strassburg, 1876. 


THE PROTEIDS OF MILK. 139 


clot with rennet at all; when it does so, the clot is a flocculent 
precipitate, which frequently redissolves rapidly in excess of gastric 
juice. According to Szontagh,! human caseiogen yields no pseudo-nuclein 
on gastric digestion; this was confirmed by Wroblewski,? who found 
also that human caseinogen has the following percentage composition— 
eon 249°H)'7°31 5° N, 149; Py 06838; L117; 0; 23°66. This; it will 
be seen, is different from the composition of the caseimogen of cows’ milk. 
Human caseinogen contains phosphorus, but not in the form of pseudo- 
nuclein, as in cows’ milk. 


Wroblewski finds that human milk contains small quantities of lact-albumin, 
and of another proteid very rich in sulphur (4°7 per cent.) and poor in carbon 
(45:01 per cent.). Lehmann and Hempel? find that the caseinogen of cows’ 
milk contains 7:2 per cent. of ash; this consists of CaO, 49°5; MgO, 2°4; 
P,O,, 47:0; and SO, 1:06 per cent. The elementary composition of the 
proteid is given as C, 50°86; H, 6°72; N, 14°63; P, 0°81; S, 0°72; ash, 6°47 
per cent. The caseinogen of woman’s milk contains more sulphur, 1:09, and 
less ash, 3°2 per cent. Some of the differences between the two caseinogens 
are doubtless dependent on the amount and nature of the ash with which they 
are associated. 

The occurrence of nucleon (phospho-carnic acid) in milk has already been 
mentioned on p. 104. Siegfried + states that the nucleon accounts for 41°5 per 
cent. of the phosphorus in human milk, but for only 6 per cent. of that in 
cows’ milk. Practically all the phosphorus in human milk is in organic com- 
bination (nucleon and caseinogen). 


Lact-albumin.—After the precipitation of casemogen and _lacto- 
globulin by half-saturation with ammonium sulphate, lact-albumium re- 
mains in solution. It can be incompletely precipitated from this solution 
by saturation with sodium sulphate. It is completely precipitated with 
the other proteids when milk is saturated with ammonium sulphate. It 
coagulates between 70° and 80° C.; in cows’ milk at 77° C. It is not 
separable, like serum albumin and egg albumin, into several proteids by 
fractional heat coagulation. It, moreover, is coagulated by heat very 
slowly; the solution must be kept some hours at 77° C., before it is 
completely precipitated. Its specific rotatory power® «p= —36", 2... less 
than that of serum albumin; it has the followimg percentage composi- 
Gomer o219; WH, 7-18; N, toi77 8, iio; 0, 2313. The high 
percentage of sulphur is another distinction between it and serum 
albumin. 

Lactoglobulin.—A trace of globulin is obtained from cows’ milk by 
saturating it with magnesium sulphate, after the removal of the 
caseinogen by saturation with sodium chloride (Sebelien). Its 
characters are like those of serum globulin. The amount of globulin in 
colostrum is considerable, but in fully-formed milk it is present in so small 
an amount that for a long time I was unable to confirm Sebelien’s state- 
ment. Hewlett,? however, who worked with me, confirmed its presence. 


1 Ungar. Arch. f. Med., Wiesbaden, Bd. i. S. 192; Jahresb. ii. d. Fortschr. d. Thier- 
Chem., Wiesbaden, Bd. xxii. S. 168. 

2 Tnaug. Diss., Bern, 1894. See also Moraczewski, Ztschr. f. physiol. Chem., Strassburg, 
1894, Bd. xx. S. 28. 

3 Arch. f. d. ges. Physiol., Bonn, Bd. lvi. S. 558. 

4 Zischr. f. physiol. Chem., Strassburg, 1897, Bd. xxii. S. 575. : 

5 Sebelien, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, Bd. xv. S. 184. 

6 Journ. Physiol., Cambridge and London, 1892, vol. xiii. p. 798. See also Arthus, Arch. 
de physiol. norm. et path., Paris, 1893, p. 673. 


140 THE CHEMISTRY OF THE TISSUES AND ORGANS. 


Kemmerich! stated that casein (7.e. caseinogen) is formed at the cost of 
the albumin of milk after secretion. He estimated the caseinogen by pre- 
cipitating it with dilute acetic acid, the precipitate being subsequently freed 
from fat by ether, dried and weighed. He estimated the albumin by weighing 
the heat coagulum after separating out the acetic acid precipitate, and he found 
that, after the milk is allowed to stand some hours at the body temperature, 
the caseinogen increases in quantity, and the albumin diminishes. Dahnhardt? 
claimed to have separated out from the cells of the mammary gland a ferment 
soluble in glycerine which hastens this process.* 

These experiments are quoted with approval by Heidenhain,* but do not 
seem to have been followed up recently by the more precise methods of 
modern milk analysis. The differences noted by Kemmerich are usually small, 
and might be well within the limits of experimental error.® They date from a 
time when lact-albumin was considered to be identical with serum-albumin, 
and when caseinogen was looked upon as nothing more than alkali-albumin. 
Among other statements made by Kemmerich is the one that lact-albumin is 
converted into casein by boiling—an assertion which is quite sufficient to show 
the somewhat crude notions prevalent at the time concerning the proteids of 
milk. The dominant idea of these workers appears to be to account for the 
milk-proteids as simple derivatives of the blood proteids. 


In the foregoing account of milk, no description of analytical processes has 
been given. For the numerous methods which may be used in this highly 
technical branch of analytical chemistry, the reader is referred to text-books 
on that science. 


1 Arch. f. d. ges. Physiol., Bonn, 1869, Bd. ii. 8. 401. 

2 Thid., 1870, Bd. iii. S. 586. 

° J. ©. Lehmann considered that caseinogen is formed from albumin by weak alkali 
(Centralbl. f. d. med. Wissensch., Berlin, 1864, S. 530). 

4 Hermann’s ‘‘ Handbuch,” 1883, Bd. v. S. 395. 

5 That this explanation is probably correct, is shown by some experiments of Schmidt- 
Miilheim (Arch. f. d. ges. Physiol., Bonn, 1882, Bd. xxviii. S. 243) and Thierfelder (cbid., 
1883, Bd. xxxii. S. 619), who, by using the same methods, found a slight diminution of the 
casein after milk had stood some hours at the body temperature. Schmidt-Miiheim sup- 
posed that on standing some of the casein is converted into peptone. 


THE BLOOD. 
By E. A. SCHAFER. 


ConTEnts :—-General Properties, p. 141—Amount, p. 141—Colour, p. 142—Specifie 
Gravity, p. 143—Reaction, p. 144—Coagulation, p. 145—Relative Amounts of 
Plasma and Corpuscles, p. 147—-Number of Corpuscles, p. 149—General Com- 
position of Blood, p. 153—Composition of Blood Corpuscles, p. 155—Composi- 
tion of Plasma, p. 156—Proteids of Plasma, p. 161—Theories of Coagulation, 
p- 168—Causes of Coagulation, p. 178—Lymph and allied Fluids, p. 181. 


THE blood is a red fluid of alkaline reaction; in man its specific gravity 
is about 1:060. It has an odour which is different in different species 
of animals, and is brought out by the addition of sulphurie acid. It 
sets more or less rapidly into a solid clot or coagulum after death, or on 
removal from the living blood vessels. It consists of a clear, yellowish 
liquid, the plasma or liquor sanguinis, and of microscopic particles or 
corpuscles of two kinds: the one kind, less numerous, termed the white, 
or colourless, or lymph corpuscles (leucocytes); the other kind, by far 
the most numerous, the red, or coloured corpuscles (erythrocytes), 
which give the blood its characteristic tint. In addition to these, a 
variable number of much finer discoid colourless particles (elemen- 
tary particles, blood-platelets) are apparent in a microscopic preparation 
of drawn blood. 

Amount.—The amount of blood in the body was determined in the 
following manner by Welcker:1—A measured sample of blood is drawn, 
and, after being defibrinated, portions of it are diluted to different degrees 
to serve as samples of comparison. The rest of the blood is then collected 
and defibrinated, and the vessels are washed out with salt solution until 
the washings are colourless: they are all added to the defibrinated blood, 
which is now diluted with water until it corresponds in tint with one of 
the above samples, the dilution of which is accurately known. The total 
quantity of blood in the vessels can then be calculated. In order to 
obtain every trace of blood, Welcker further minced up the whole 
animal and extracted the tissues with water, adding this to the mass 
of blood. Some hemoglobin would thereby, however, be yielded by the 
muscles (Kiihne). 

The amount has also been determined during life by the method 
of Gréhant and Quinquaud,? who allowed an animal to inspire a 


1 Ztschr. f. rat. Med., 1858, Ser. 3, Bd. iv. S. 147. Welcker’s method is improved 
by combining the hemoglobin with carbonic oxide gas (Gescheidlen). 

2 Compt. rend. Acad. d. sc., Paris, 1882, tome xciy. p. 1450; Journ. de Uanat. et 
physiol. etc., Paris, 1882, No. 6, p. 564. 


142 THE BLOOD. 


measured amount of carbonic oxide (mixed with oxygen); then drew 
off a measured quantity of blood, and determined the amount of carbonic 
oxide this contained; the amount in the whole of the blood in the body 
would be in the same proportion, and the quantity of blood could thus 
be calculated. The result arrived at by these two methods is that the 
blood is equal to one-eleventh to one-fourteenth of the body weight 
(about 53 kilos. in a man of 70 kilos.). 

_ Colour : laking of blood.—The colour of the blood varies in different 
parts of the vascular system. The differences are dependent upon the 
amount of oxygen in combination with the hemoglobin. The colour 
also becomes altered by any reagent or circumstance which tends to 
cause the hemoglobin to pass out from the corpuscles into the cireum- 
jacent fluid. When this is brought about, the blood loses its opaque 
appearance and becomes transparent and of a laky tint. Such “laky” 
blood is readily produced by the addition of distilled water, and also by 
water holding neutral salts in solution up to a certain percentage ; which 
percentage varies for different salts, and also, with the same salts, for the 
blood of different animals. A solution containing just such a percentage 
of salt as suffices to keep the corpuscles unaltered in form, and without 
removal of any of their hemoglobin, is “isotonic” ;+ solutions below and 
above such strength are respectively “ hypisotonic ” and “ hyperisotonic.” 2 
For human blood, a solution of common salt is isotonic with a percentage of 
0-9 ; for defibrinated ox blood, with 0°6, and about the same for frog’s blood. 
Very slight differences of external condition will tend to alter the per- 
meability of the blood corpuscles both for hemoglobin and for other 
substances. A minute diminution in the alkalinity, such as is produced 
by the addition of 0-003 per cent. HCl, so alters the permeability as to 
cause proteid to pass from the corpuscles into the serum, and chlorides or 
phosphates to pass into the corpuscles from the serum ; a minute increase 
of alkalinity has the opposite effect. The passing of oxygen and carbonic 
acid respectively through blood produces like physical changes, and it has 
been suggested that these changes may come into operation in connection 
with the metabolic exchanges in the capillaries? These osmotic effects 
alter the total volume of the corpuscles as compared with the plasma; 
the proportional alterations are determined by centrifugalising blood, 
and then measuring the respective amounts of subsided corpuscles and 
superjacent plasma. Laky blood is produced not only by water and 
dilute solutions of neutral salts, but also by many other reagents or con- 
ditions, such as crushing of the corpuscles, freezmg and thawing the 
blood, and also by the action of acids, of alkalies, of bile salts, of ether and 
chloroform, of heat and electricity. In all cases the permeability of 
the envelope of the red corpuscle (see p. 154) becomes altered either by 
mechanical means or by the solution of one or more of its constituents, 


1 Having the same osmotic pressure (de Vries, Zéschr. f. physikal. Chem., Leipzig, 1888, 
Bd. ii. S. 415). 

* Hamburger, Arch. f. Physiol., Leipzig, 1886, S. 476; Ztschr. 7. Biol., Miinchen, 1890, 
Bd. xxvi. S. 414. 

®° Hamburger, Zischr. f. Biol., Miimchen, 1892, Bd. xxviii. S. 405; Arch. f. Physiol., 
Leipzig, 1892, S. 513; 1893, Suppl. Heft, S. 153 ; and Verhandel. d. k. Akad. v. Wetensh. 
te Amsterdam, 1897, S. 368. 

4 Koeppe, Arch. f. Physiol., Leipzig, 1895, S. 154; Hedin, Skandin. Arch. f. Physiol., 
Leipzig, 1895, Bd. v. S. 207 and 238. 

> For literature of this, see Rollett in Hermann’s ‘‘ Handbuch der Physiologie,” Bd. iv. 
8. 14. 


SPE CIPIGIGRAVIT Y. 143 


and the hemoglobin is thereby permitted to diffuse into the circumjacent 
fluid. 

Specific gravity.—The specific gravity of the blood varies in health 
within small limits, namely, for men, 1057 to 1066; for women, 1054 to 
1061.1 According to Lloyd Jones,” it is lower than this in women, averaging 
1051°5 between the ages of 35 and 45, whereas in men of the same age it 
averages 1058°5. It falls a little when much fluid is injected, and is raised 
a little by profuse perspiration, but the changes thus produced are very 
small? It is slightly less in children than in adults, but it is higher in 
the fcetus than in the mother; and it is highest in the child at term, in 
which it is 1066, the specific gravity of the maternal blood being then 
only about 1050.4 The diurnal variations are normally so small as to be 
almost negligeable. Passive congestion of the part from which the speci- 
men exanuned is taken increases the specific gravity, whereas active con- 
gestion lowers it. It varies also according to the part of the body from 
which it is taken, such variation being probably due to accidental admix- 
ture with lymph. Thus Lloyd Jones found a difference of as much as 
three or four per 1000 between blood from the finger (lower) and blood 
from the skin over the shin (higher). Of the animals examined, it has 
been found higher in birds than mammals, and to vary somewhat in these 
animals in different species. The variations in age and sex are closely 
related to variations in the amount of hemoglobin. Saline solution 
(NaCl, 0°75 per cent.) injected in quantity into the blood only depresses 
the specific gravity for a short time. The specific gravity of blood from 
a vein is practically the same as that from the corresponding artery, if 
care be taken to avoid venous congestion.® 

The specific gravity of the blood falls after the removal of blood, 
doubtless from absorption of the specifically lighter lymph from the 
tissues. It subsequently (in about six hours) not only returns to 
normal, but even rises above normal; after about twelve hours it has 
permanently recovered its normal specific gravity.® 

Almost any operation performed upon an animal, especially one 
involving exposure or uritation of a serous membrane, will produce an 
increased percentage of corpuscles (polycythemia), or a corresponding 
diminution of plasma. This is due, not to increased formation of cor- 
puscles, but to exudation of plasma in the inflamed or irritated part.’ 


1Hammerschlag, Zischr. f. klin. Med., Berlin, 1892, Bd. xx. S. 444. The results of 
other workers will be found in this paper. For the older literature, see Rollett, op. cit., S. 
134. The numbers given by Peiper (Centralbl. f. klin. Med., Bonn, 1891, Bd. xii. S. 217) 
are 1°055 as the average for men, and 1°053 for women. 

2 Journ. Physiol., Cambridge and London, 1888, vol. viii. p. 1. 

3 Schmaltz, Arch. f. klin. Med., Berlin, 1891, Bd. xlvii. S. 145; Grawitz, Zétschr. 7. 
klin. Med., Berlin, Bd. xxi. 8. 459, and Bd. xxii. S. 411. 

4 Lloyd Jones, op. cit. 

®>Cohnheim and Zuntz, Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xlii. S. 3038. 
For the effects of varying conditions of health and disease upon the specific gravity 
of the blood consult Lloyd Jones, Journ. Physiol., Cambridge and London, 1891, vol. xii. 
p- 299, where a large number of observations are accumulated. Lloyd Jones worked by 
Roy’s method. Scholkoff (Diss., Bern, 1892), working by a different method (pycnometer), 
has obtained very similar results. Both observers agree in the important fact that the 
specific gravity varies as a rule pari passw with the richness in hemoglobin. For the 
specific gravity in different animals, and for variations experimentally induced, see Sher- 
rington and Copeman, Journ. Physiol., Cambridge and London, 1893, vol. xiv. p. 52. 

8 Ziegelroth, Virchow’s Archiv, 1895, Bd. elxi. S. 395. 

7 See on this subject, Lowit, ‘‘Studien z. Phys. u. Path. d. Blutes,” Jena, 1892; W. 
Hunter, Journ. Physiol., Cambridge and London, 1890, vol. xi. S. 115; Sherrington and 
Copeman, /oc. cit.; Sherrington, Proc. Roy. Soc. London, 1893, vol. lv. p. 161. 


aa 9 THE. BLOOD. 


The methods which have been used for determining the specific gravity of 
the blood are—(1) that of directly weighing a sample (pycnometer), and (2) 
Roy’s method. The latter is by far the readiest, and, for small quantities of 
blood, the more accurate. It consists in transferring minute drops of blood to 
glycerine and water, mixed in varying proportions, and forming a graduated 
series of liquids of different and known specific gravities, and in observing in 
which mixture the drop tends neither to rise nor to fall. The method has been 
modified by the use of benzene and chloroform mixtures instead of glycerine and 
-water, and also by placing the drop of blood in such a mixture, and adding benzene 
or chloroform, as the case may be, until the drop remains exactly suspended, 
tending neither to rise nor fall; the specific gravity of the mixture is then 
taken (Hammerschlag). It may be doubted, however, whether these modifica- 
tions are more readily applied, or more accurate than Roy’s method. 


Reaction.—The alkaline reaction of the blood is easily recognised, in 
spite of its red colour, by applying a drop of blood to the surface of a piece 
of glazed litmus paper, and after half a minute wiping away the blood 
with a piece of clean linen, wetted with distilled water or with neutral 
salt solution. The part of the paper which was covered by the blood 
will show a blue patch.) A comparison may be made between different 
samples of blood, by using a series of litmus papers which have been 
reddened by standard acid of different strengths.” For estimating the 
amount of its alkalinity the blood is mixed in small measured quantity 
with a solution of sulphate of soda, containing a definite amount of 
tartaric acid, titrated against sodium hydroxide, and the mixture found 
which is exactly neutral to glazed litmus paper. Tested by this method, 
the alkalinity of human blood is found to be equal to about 0-200 
grms. of sodium hydroxide per 100 cc. blood® There appears to be 
a diurnal variation, the alkalinity being lowest in the morning, and 
gradually rising in the afternoon, becoming less again in the evening. It 
rises during digestion.6 It is diminished by muscular work, especially 
with a diet containing little or no proteid.7 On the other hand, with a 
diet rich in proteids, it undergoes very little alteration. In accordance 
with this, it is found that carnivora resist an artificial diminution of the 
normal blood alkalinity (such as would be caused by giving dilute mineral 


1 Schafer, Journ. Physiol., Cambridge and London, 1881, vol. iii. p. 292. 

2 Haycraft and Williamson, Proc. Roy. Soc. Edin., 1888, vol. xv. p. 396. For fallacies 
in the Clinical application of this method, see Hutchison, Lancet, London, 1896, vol. i. 
». 616. 
ie: Lassar, Arch. f. d. ges. Physiol., Bonn, 1874, Bd. ix. S. 44; Drouin (These, Paris, 
1892) used oxalic acid. 

4The principle of the method is due to Zuntz, who, however, used phosphoric acid 
(Centralbl. f. d. med. Wéissensch., Berlin, 1867, S. 801); but the details were greatly 
improved by Landois (‘‘ Real-Encyklopidie,” Aufl. 2, Bd. iii., article ‘*Blut”). For other 
methods of estimating the alkalinity, see v. Limbeck, Wien. med. Bi., 1895, S. 295 ; and 
Schutz-Schultzerstein, Centralbl. f. d. med. Wissensch., Berlin, 1894, Bd. xxxii. 8. 801. 
According to Mayer (Arch. f. exper. Path. wu. Pharmakol., Leipzig, 1883, Bd. xvii. S. 304), 
all titration methods are unreliable with blood, but his conclusions have not been accepted 
by most physiologists. 

5 Freudberg, Virchow’s Archiv, 1891, Bd. cxxv. S. 566, gives an average alkalinity in 
health of 0-200 to 0:240 grm. NaHO per cent. Jeffries (Boston Med. and S. Journ., 1889) 
obtained about 0'200 as the average, and Drouin about 0°206. v. Jaksch. (Zétschr. f. klin. 
Med., Berlin, 1888, Bd. xiii. S. 353) found the alkalinity of normal human blood as high 
as 0°260 to 0°300.; Loewy (Arch. f. d. ges. Physiol., Bonn, 1894, Bd. lviiii. 8. 498), working 
with ‘‘laked” blood, found its alkalinity=0°449 grms. NaHO ; and Berend (Zéschr. /. 
Heilk., Berlin, 1896, S. 351) obtained an alkalinity from “ laked” blood of 0°450 to 0°500. 

6 Peiper, Virchow’s Archiv, 1889, Bd. exvi. 8. 337. 

7 Cohnstein, Virchow’s Archiv, 1892, Bd. exxx. S. 332. See also Geppert u. Zuntz, 
Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xlii. S. 233, and Peiper, Joc. cit. 


‘ 


COAGULATION. 145 


acids by the mouth), whereas herbivora show no such resistance.’ The 
result appears to be due to the fact that ammonia becomes split off from 
the superabundant proteid in place of urea, and serves to unite with 
and neutralise the excess of acid. 


Kraus found the alkalinity to be diminished by laking the blood, ze. the 
blood to become more acid after the corpuscles are broken up, but Loewy and 
others have found it to be very high under these conditions ; alkaline substances 
in the corpuscles coming also into estimation.? It is diminished after with- 
drawal, and during the process of coagulation (Zuntz) ;? when this is completed, 
it is about ‘04 grm. NaHO less. The alkalinity is also diminished in fever and 
in many diseases. In diabetic coma‘ and in the cold stage of cholera’ an 
acid reaction has even been detected. The diminution of alkalinity is accom- 
panied by a diminished amount of carbonic acid in the blood. 


The alkalinity is usually stated to be due to carbonate and phosphate 
of soda. This may be true for the alkalinity of the plasma, but it is 
insufficient to account for that of the corpuscles as well, and in them is 
probably largely due to the presence of organic substances of weak basic 
nature. Thus it was found by Zuntz and Lehmann,® that whereas a 
sample of calcined blood showed an alkalinity equivalent to 0°240, and 
the estimation of the alkalinity of the same blood by the amount of 
carbonic acid it would combine with gave an alkalinity equal to 0:276, 
the estimation by titration of the same blood after laking gave a result 
as high as 0°832. Saturation of blood with carbonic acid causes the 
corpuscles to become less and the serum more alkaline.’ 

Although the blood is alkaline in reaction to litmus, it contains salts 
(hydrodisodie phosphate and sodic bicarbonate) which are theoretically 
acid’ having the power both of fixing bases and of turning other acids 
out of combination (Rollett). In this sense the “acidity” as well as the 
“alkalinity” of the blood can be spoken of. According to Kraus ® it is 
normally equivalent in venous blood to from 0°162 to 0-232 grm. NaHO per 
100 grms. blood ; being increased in conditions of fever to 0-272 grm., and 
in diabetic coma to 0°547 germ. 

Coagulation.—The blood begins to coagulate three or four 
minutes after it is drawn, and the process is completed in seven 
or eight minutes.° The process is hastened by warmth, by agita- 

1 Walter, Arch. f. exper. Path. u. Pharmakol., Leipzig, 1877, Bd. vii. S. 148. 

2 Kraus, Ztschr. f. Heilk., 1890, Bd. x. 8.106; Arch. f. exper. Path. u. Pharmakol., 
Leipzig, 1889, Bd. xxvi. S. 186 ; Winternitz, Zischr. f. physiol. Chem., Strassburg, 1891, 
Bd. xv. S. 505 ; Loewy, Arch. f. d. ges. Physiol., Bonn, 1894, Bd. viii. S. 462; also Loewy 
and Zuntz, ibid., S. 511, and Lehmann, ibid., S. 428. See note on p. 144. 

° See also Loewy and Zuntz, Arch. f. d. ges. Physiol., Bonn, 1894, Bd. lvili. S. 507. 

4 Minkowski, Arch. 7. exper. Path. u. Pharmakol., Leipzig, Bd. xix. S. 209; Mitth. 
a. d. med. Klin. z. Kénigsberg, Leipzig, 1888, S. 174. 

5 ©. Schmidt, ‘“Charakt. d. epid. Cholera,” Leipzig, 1850 ; Straus, Roux, Thuiller et 
Nocard, Compt. rend. Soc. d. biol., Paris, 1883, S. 569. 

6 Arch. f. Physiol., Leipzig, 1893, S. 556. 

7 Zuntz in Hermann’s ‘‘ Handbuch,” 1880, Bd. iv. Th. 2, S. 77. 

8 Maly, Sitzwngsb. d. k. Akad. d. Wissensch., Wien, 1878, Bd. lxxvi. Abth. 2, S. 21 ; 
and ibid., 1882, Bd. Ixxxv. Abth. 3, S. 314. 

° Op. cit. 

10 Hewson, ‘‘ Properties of the Blood,” 1772. In ‘‘ Works,” edited by G. Gulliver for 


the Sydenham Society, p. 24. Blood from the hepatic veins coagulates rather more 
slowly than blood from other parts of the vascular system. Paulesco (Arch. d. physiol. 


- norm. et path., Paris, 1897, p. 21) states that blood from the portal vein from animals in full 


digestion of proteid food may take as long as fifty minutes to coagulate, but otherwise there 
is little difference in blood from different vessels. For a method of accurately estimating 
the time of commencing coagulation, see Brodie, Journ. Physiol., Cambridge and London, 
1897, vol. xxi. p. 403. 

VOL. I.—I10 


146 THE BLOOD. 


tion, by contact with foreign matter, by moderate dilution with water, 
by addition of calcium salts, and by fibrin ferment and nucleo-proteids. 
It is delayed by cold, by dilution with solutions of neutral salts 
or of sugar, by intravenous injection of albumose, and of various 
other organic substances, such as diastatic ferments; also by prevention 
of contact with foreign matter, as by drawing it into oil. It is also 
prevented if the soluble lime salts are precipitated by soluble oxalates, 
“by fluorides, or by soap. A temperature of 56° C. prevents coagulation 
by precipitating ‘the fibrinogen upon which the coagulation depends. 
It remains fluid for an indefinite time within the living blood vessels, 
even in a portion of vessel which has been isolated by ligatures. But if 
the imner surface of any blood vessel is injured, the ‘blood tends to 
deposit a coagulum upon the injured part. And if a foreign substance 
is introduced into a blood vessel a clot forms wpon it. 

It also coagulates within the vessels of a living animal if a solution 
of nucleo-proteids is injected in a certain amount into the veins (Wool- 
dridge) ;1 but if the amount injected is too small to cause coagulation, the 
opposite effect is obtained, the coagulability being temporarily destroyed 
(negative phase, Wooldridge). These effects are not peculiar to nucleo- 
proteids, but have been shown to be also produced by intravenous injection 
of artificially prepared “ colloids”? (see p. 37), and by snake-venom.® 

If the coagulation is prevented by any of the above means, the cor- 
puscles, which are heavier than the plasma, tend to fall to the bottom of 
the vessel, and to leave the upper layers of plasma clear. At the junction 
between the mass of subsided red corpuscles and the plasma is a “ buffy ” 
layer containing most of the white corpuscles. The subsidence may be 
accelerated by centrifugalisme the blood. If cold be used to delay the. 
coagulation, or if the blood be contained in a ligatured vein, carefully 
removed from an animal immediately after death, and suspended in a glass 
vessel, pure plasma may be drawn off from the upper layer completely free 
from red corpuscles, but usually containing a few leucocytes. The experi- 
ment is best performed with horse’s blood, the corpuscles being relatively 
heavier in this as compared with that of other animals. This plasma 
clots on being placed in a glass vessel at the temperature of the air, but 
much more slowly than a sample of the original blood, and the more 
slowly the fewer the blood platelets and leucocytes it contains. Ifa 
sample be taken from the buffy layer—containing, therefore, many leuco- 
cytes and many blood platelets—the clotting is speedy and firm. IH 
bird’s blood is rapidly and repeatedly centr ifugalised, plasma is obtainable 
almost entirely free from corpuscles, and no clotting occurs in it for 
days on standing in a glass vessel. It appears, ther efore, that the 
coagulation is independent of the red corpuscles, and is dependent 
upon the plasma and white corpuscles, and perhaps also upon the 
blood platelets. It is also dependent upon the presence of calcium 
salts. The exact relations which these factors bear to one another in 
the phenomenon of coagulation will be discussed later in considering the 
properties of fibrinogen. 

The delay of coagulation produced by neutral salts is best obtained 


1 Proc. Roy. Soc. London, 1886, vol. xviii. p. 186; Arch. f. Physiol., Leipzig, 1886, 
S. 397. 

* Pickering, Journ. Physiol., Cambridge and London, 1895, vol. xvii. (Proc. Physiol. 
Soc., p. Vv); and Halliburton and Pickering, ibid., 1895, vol. xviii. p- 285. 


°C. J. Martin, Journ. and Proc. Roy. Soe. New South Wales, Sydney, 1895. 
+ Delezenne, Compt. rend. Soc. de. biol., Paris, 1896, p. 782. 


RELATIVE AMOUNT OF PLASMA AND CORPUSCLES. 147 


by allowing the blood as it flows from a cut artery to mix with an equal 
volume of saturated solution of sulphate of soda or with a 10 per cent. 
solution of sodium chloride, or with one-third its bulk of a saturated 
solution of sulphate of magnesia. The plasma obtained after subsidence 
of the corpuscles is in these cases diluted with the salt solution (salted 
plasma), and may remain indefinitely uncoagulated. But, on diluting it 
with a sufficient amount of water, coagulation will usually occur. The 
delay produced by albumoses (commercial “peptone” is generally used) 
is obtained by injecting these, in the proportion of 03 grm. per kilog. of 
body weight into the circulating blood of a dog or cat.1_ The effect is 
not got in the rabbit.2, Malt diastase and emulsin in somewhat larger 
quantity have a similar effect. The blood of such a “ peptonised ” 
animal does not clot on being drawn, but it coagulates on passing 
carbonic anhydride through it, or on diluting it with water. Extract of 
leech-heads,* which contains an albumose,’ and also extract of crayfish 
muscle(Heidenhain),act similarly in preventing coagulation, but in smaller 
doses. Leech extract does not, however, act exactly in the same manner as 
albumose, for the latter does not arrest coagulation if added in moderate 
quantity to drawn blood, whereas leech extract does arrest it (Haycraft). 

To hinder coagulation by removal of lime salts, the blood is mixed as it 
flows from the vessels with a small amount of solution of sodium oxalate ; 
1 part of the salt to 1000 parts of blood is suffiaent.6 The corpuscles 
usually subside very readily in oxalated blood, and a clear plasma, nearly 
but not quite free from soluble lime salts, is easily got from it, coagulating 
quickly on the addition of chloride of calcium. It is not, however, the 
case that, as Arthus has asserted, oxalated blood or plasma always 
remains indefinitely uncoagulated without the addition of lime salts, 
for on allowing it to stand a few days a clot is frequently found in it.’ 

All the above methods yield plasma, either pure or in a somewhat 
modified condition. To obtain the blood corpuscles free from plasma it 
is necessary, after drawing off the superjacent fluid from them, to mix 
them with a further quantity of the salt solution used to prevent 
coagulation (e.g. 10 per cent. NaCl), and again to centrifugalise. Or 
the blood may be mixed as soon as drawn with a sufficient quantity of 
isotonic salt solution to delay its coagulation, and centrifugalised. By 
repeating the process several times the corpuscles may be got free from 
plasma, and may thus be analysed separately from the liquor sanguinis. 
But it is by no means certain that they have not undergone some altera- 
tion in composition by diffusion. Hitherto no means has been devised 
for meeting this objection. 

Relative amount of plasma and corpuscles.—The relative amounts 
of plasma or serum and corpuscles can therefore only be found approxi- 
mately by weighing the corpuscles obtained by this method from a 
given amount of blood. Indirectly, it has been arrived at for defibrin- 
ated blood by Hoppe-Seyler, by determining the percentage amount of 

1 Schmidt-Miilheim, Arch. f. Physiol., Leipzig, 1880, S. 33. 

2 Fano, ibid., 1881, S. 276. 

8 Salvioli, Arch. per le se. med., Torino, 1888, vol. xii. p. 245. 

4 Haycraft, Proc. Roy. Soc. London, 1884, vol. xxxvi. p. 478. Haycraft showed that leech 
extract acts by destroying fibrin ferment. 

> Dickinson, Journ. Physiol., Cambridge and London, 1890, vol. xi. p. 566. 

6 Arthus et Pagés, Arch. de physiol. norm. et path., Paris, 1890, p. 739. 

7 This is certainly so with the plasma obtained from oxalated dog’s blood and sheep’s 
blood (Schafer, Proc. Physiol. Soc., Journ. Physiol., Cambridge and London, 1895, vol. 
XVll. p. XX). 


148 THE BLOOD. 


proteids in the serum, and of proteids and hemoglobin in the subsided 
corpuscles, and in the whole blood respectively; and, calculating from 
the results obtained, the amount of plasma and of corpuscles respectively 
in 100 grms.*. An earlier method consisted in determining the amount 
of fibrin in a given quantity of the whole blood, and of the plasma 
respectively, and from this calculating the percentage amount of plasma 
in the sample of blood.?, Bunge determined the proportions in a similar 
manner by estimating the sodium in a sample of blood, and also in 
plasma of the same blood. This method is only applicable to certain 
animals (horse, pig) which have no sodium in their blood corpuscles. 


The following example of the application of these methods is given by 
Bunge :°— 

(A) By Hoppe-Seyler’s method :— 

In 100 germs. of defibrinated pig’s blood were found— 

(a) 18-92 Aha sited, 
(b) 18°88 { ; 
In the blood corpuscles of 100 grms. of the same blood— 
(a) 15-04 
(d) 1513 mean: 15°07 grms. proteids + hemoglobin. 
(c) 15°05 
In the serum of 100 germs. of blood were— 
18:90 — 15:07 =3°83 grms. proteids. 

In 100 grms. of serum— 

(a) 6-74 | 
(b) 6°79 J 

From this the amount of serum in 100 germs. of the defibrinated blood 
may be computed— 

6-77 : 3°83 :: 100 : 5655. 

Therefore 100 grms. blood contained 56°5 parts serum and 43°5 corpuscles. 
(B) By estimation of sodium— 

In 100 grms. of the whole blood of the same pig was found— 

ee mean : 0:2406 grms. Na,O. 

(b) 0°:2409 3 2 
In 100 grms. of serum— 

© ee mean : 0°4272 grms. Na,O. 

0:4272 : 02406 :: 100: 56:3. 

Therefore, by this method, 100 grms. blood contained 56°3 parts serum 
and 43:7 corpuscles—a result which agrees closely with that obtained by Hoppe- 
Seyler’s method. 

Similarly, in horse’s blood, Bunge found by Hoppe-Seyler’s method 46°5 per 
cent. serum, and 53:5 corpuscles, and by the sodium method 46°9 serum and 
53°1 corpuscles. 


18:90 grms. proteids + hemoglobin. 


mean: 6°77 proteids. 


A rapid approximate determination may be made by Blix’s method 
(hematocrit). The blood is mixed with a definite amount of 23 
per cent. potassium bichromate, and centrifugalised. The corpuscles 
rapidly accumulate at the bottom in an almost solid mass, and their 


1 “ Handb. d. physiol. chem. Analyse,” Aufl. 2, Berlin, 1865. 

* Hoppe, Virchow’s Archiv, 1857, Bd. xii. S. 483. 

3 «Physiol. and Pathol. Chemistry,” trans. by Wooldridge, 1890, pp. 243, 244. 

* Hedin, Skandin. Arch. f. Physiol., Leipzig, 1890, Bd. ii, S, 134. Gaertner, Berl. med. 
Wehnschr., 1892, No. 36, p. 890. 


THE NUMBER OF CORPUSCLES. 149 


collective volume can be directly read off The estimation can be made 
with a small quantity of blood, and is therefore capable of being used for 
clinical purposes. The average percentage of corpuscles in human 
blood, as obtained by 
these several methods, 
is about 48, or very 
nearly one-half of the 
entire amount of blood. 
In the horse it is 53 
per cent., in the pig 
43°5 per cent., in the 
dog 35°7 per cent., 
and in the ox 32 per 
cent. Hedin obtained 
in himself an average 
percentage total cor- 
puscular volume of 51, 
the greatest differences 
in his own blood being 
54-4 and 48 per cent. ; 
but the average for a 
large number of adult 
males was 48 and of 
females 43:3. In chil- 
dren of 6 to 13 years 
the amount was 45 per 
cent. 

Number of corpus- 
cles.—The number of 
red corpuscles in a 
cubic millimetre of 
blood was determined 
by Vierordt and Wel- 
cker to be about 
5,000,000 in adult 
men. There are rather 
fewer in women (about 
4,500,000). Vierordt’s = 
method consisted in Fic. 21.—Oliver’s apparatus for estimating the number of 
diluting the blood with blood. corpuscles. a, measuring pipette ; 6, dropper to 
Pier etcmnount, of | cette areata ne a ae abe ete 
fluid which would pre- must be done in a dark room.) at, b, and are natural size. 
serve the corpuscles, 
and counting the number ina measured amount of the mixture. The same 


method is still in use, but its application has been greatly simplified in the 


i 


; 


— 
NS) 
=) 


uy 


HT 


=) 
S 


HI 


69 


LIJHN 
=) 
S 


HHT 


I 


NS) 
S 


Ta 


1 An indirect method, based on the principle of centrifugalising blood with varying 
amounts of salt solution, and determining the organic nitrogen in the supernatant fluid, has 
been introduced by M. and L. Bleibtreu (Arch. f. d. ges. Physiol., Bonn, 1891, Bd. li. 8. 151), 
who claim to be able to estimate by its aid, not only the total corpuscular volume, but even 
the average volume and weight of a single blood corpuscle. The method has, however, 
been sharply criticised. (Hamburger, Centraibl. f. Physiol., Leipzig, 1893, Bd. vii. S. 161; 
and Virchow’s Archiv, 1895, Bd. exli. 8S. 230; Eyckmann, Arch. f. d. ges. Physiol., Bonn, 
1895, Bd. Ix. S. 340; and Hedin, zbid., S. 360). See further, on the same subject, Lange, 
ibid., 1892, Bd. lii. S. 427, and Bleibtreu, ibid., Bd. lx. S. 405. 


150 PHEVELOCD. 


blood-counting apparatus (hemacytometer) of Gowers and of Thoma. 
The hematocrit can also be employed, since it has been determined (by 
exact enumeration) that each volume per cent. shown by that instrument 
represents 97,000 corpuscles. <A still readier mode of rapidly estimat- 
ing the number of red corpuscles in a sample of blood is that of G. 
Oliver.? Oliver takes a small measured quantity of blood and mixes it 
in a graduated glass tube with Hayem’s fluid,* until the flame of a candle 
‘placed at a certain distance behind becomes apparent through the mix- 
ture. With 5,000,000 corpuscles per cent. the mixture will now be 
found to fill the tube to a certain point. This point is taken as the 
normal (or 100 per cent.), and above or below it the tube is graduated 
in percentages. The fine flutings which are produced in drawing out 
the tube enable the point at which the flame first becomes visible to be 
determined with great accuracy, for they cause it to appear as a trans- 
verse luminous line, and it is in this factor that Oliver’s application of the 
method is superior to previous attempts that have been made to apply it. 
The following results have been obtained by Oliver and others :— 
There is a diurnal variation in the percentage of corpuscles, which 
falls somewhat during the daytime and rises at night. This variation 
amounts to between 4 and 5 per cent. of the normal number. Food 
usually produces a fall in the number of red corpuscles, independent of 
the amount of water taken with the meals. The posture of a limb has 
a considerable influence on the number of corpuscles obtained from it 
by a prick, probably in keeping with alterations in the intracapillary 
pressure, which governs the production of lymph. Muscular exercise, 
whether active or passive (voluntary movements, electrical stimulation, 
massage, passive movement of limbs), causes an increase in the per- 
centage of the corpuscles, which is sometimes very marked. This may 
also be due to a difference in the production and flow of lymph in 
the part. The number is increased in the case of residents in high 
altitudes (to as much as 8,000,000! per emm.).° This appears to be 
due, partly to increased evaporation from the general surface, and loss 
of water from the blood; partly to increased arterial tension, which 
increases the amount of lymph formed; probably not to increased 
formation of red corpuscles.6 It is also increased in certain diseased 
conditions (¢.g. gout), but more commonly it is diminished in disease. 


* Lancet, London, 1877, vol. ii. p. 797 ; Virchow’s Archiv, 1882, Bd. lxxxvii. 8. 201. The 
older literature is given by Rollett in Hermann’s ‘‘ Handbuch,” 1880, Bd. iv. Th. 1, S. 27-31. 

? G. Oliver, Croonian Lectures, Lancet, London, 1896, vol. i. 

* Distilled water, 200 c.c.; sulphate soda, 5 grms.; common salt, 1 grm.; corrosive 
sublimate, 0°5 grm. See Hayem (‘‘Du Sang,” Paris, 1889), where will be found an 
extended series of observations upon the microscopical characters of the blood. 

* Noted also by Malassez, Compt. rend. Soc. d. biol., Paris, séance du 31 Oct. 1874, Gaz. 
méd. de Paris, 1874, p. 573. For numerous other observations by this author consult ‘‘ De 
la numeration des globules rouges du sang,” Paris, 1873, and papers in Arch. de physiol. 
norm. et path., Paris, 1874, et seq. 

° Viault, Compt. rend. Acad. d. sc., Paris, 1890, tome exi. p. 917 ; and 1891, tome exii. 
p: 295. Oliver (Croonian Lectures, Lancet, London, 1896, vol. i. p. 1782) gives a useful 
epitome of what is known at present on this subject, together with many original observa- 
tions. 

° Grawitz, Berl. klin. Wehnsehr., 1895, S. 713 and 740. Cf. also A. Fick, Arch. f. d. 
ges. Physiol., Bonn, 1895, Bd. lx. S. 589. Grawitz points out that at altitudes below 
16,000 feet there is no need for a compensatory increase in number of red corpuscles, since 
the experiments of Friinkel and Geppert have shown that in dogs subjected to an atmo- 
spheric pressure, equal to that at this altitude, there is just as much oxygen taken up by 
the blood as at the ordinary pressure. Miintz found relatively more iron in the blood 
of rabbits and sheep from near the top of the Pic du Midi than in others living in the 


THE AMOUNT OF HAMOGLOBIN. 151 


Stierlin! found individual variations in healthy men, amounting 
to 1,650,000, and in healthy women to 2,230,000 per c.mm.  E. Schiff? 
obtained more than 5,500,000 per cmm. in new-born children: as 
development progresses, the number suman i 
gradually sinks to about 5,000,000. 

There is normally no difference 
between the number of corpuscles in 
corresponding arteries and veins, pro- 
vided there exists no congestion of 
the part due to venous obstruction. 
In such a case the exudation of 
lymph from the capillaries increases 
the number of corpuscles per cent. 
in the blood of the vem. Capillary 
blood is poorer in corpuscles than 
that of the trunks, but the proportion 
varies with their width-and the rate 
of the blood stream.* 

Equally important for clinical pur- 
poses, with the determination of the 
number of red blood corpusclesas com- 
pared with the normal, is the estima- 
tion of the amount of hemoglobin, 


a 
Fic. 22.—Oliver’s hemoglobinometer. e, glass cell for receiving the blood from the 
pipette: the dilution is effected within the cell itself. a, standard graduations 
made of tinted glass. To avoid multiplying these unduly they are furnished in tens 
per cent., the intermediate divisions of the scale being obtained by superposing tinted 
glass riders in a graduated series from 1 to 9. (These riders are not represented in 
the figure). The apparatus is shown of the natural size. 
§ Pl 
and the consequent determination of the proportionate amount of heemo- 
slobin per blood corpuscle. This may be expressed as a quotient thus :— 
5 
percentage amount of hemoglobin _ 100 : 
- o—________s___ ——_ =| or normal 
percentage nuniber of corpuscles 100 
at least theoretically: practically it is found to vary in health from 


plains (Compt. rend. Acad. d. sc., Paris, 1891, tome exii. p. 298). Weiss, who kept rabbits 
at high altitudes for about four weeks, and compared them with control animals at lower levels, 
found an increase of corpuscles to the extent of 12 to 24 per cent., but no absolute increase of 
hemoglobin in the whole body (Ztschr. f. physiol. Chem., Strassburg, 1897, Bd. xxii. 8. 526). 

1 Deutsches Arch. f. klin. Med., Leipzig, 1889, Bd. xlv., S. 75 and 256. 

2 Zischr. f. Heilk., 1890, Bd. xi. 

3 Cohnstein and Zuntz, Arch. f. d. ges. Physiol., Bonn, Bd. xlii. 8. 303. 


152 THE BLOOD. 


0°95 to 1:05 in men, and from ‘9 to 1 in women. This “blood 
quotient ” has been also termed “ the worth” of a corpuscle.* 


The more exact methods for the determination of the amount of hemo- 
globin in blood are dealt with elsewhere (see article on Hemoglobin). For 
clinical purposes a comparison with a standard colour of the colour of the 
blood diluted to a known amount is found to give sufficiently accurate results. 
The chief methods used have been—(1) That of Gowers,*? who employs picro- 
carmine gelatin as a standard; (2) that of F. Hoppe-Seyler,t who combines 
the hemoglobin with carbonic oxide, and compares it with a standard solution 
of CO hemoglobin ; and (3) that of v. Fleischl, who used a wedge of tinted 
glass as a comparison. The method of v. Fleisch] is by far the most con- 
venient. It has been greatly improved by Oliver, who has adapted to it 
the principle of Lovibond’s tintometer.®° Thus modified it takes the form of 
a series of tinted glasses, one of which represents accurately the colour of a 
measured amount of normal blood diluted with water and placed in a flat 
glass cell of a certain size, whilst the others represent percentages of hamo- 
globin below and above the normal (Fig. 22). The blood is measured ina 
pipette similar to that shown in Fig. 21, a.® 


The number of white corpuscles in a cubic millimetre of blood is 
usually stated as 10,000, but it varies greatly even in health. By far 
the larger proportion (70 to 90 per cent.) are of the finely granular 
oxyphil variety.’ Of the rest less than 5 per cent. are coarsely granular 
oxyphil cells, while the remainder, except a few which are hyaline, 
contain basophil granules. 

Injection of many substances (peptones, nuclein, leech extract) into 
the vessels causes an immediate and marked diminution in the number 
of the leucocytes, chiefly affecting the finely granular kind (leucocytopente 
phase, Lowit) ;8 it is followed by an increase in their number (leucocytotie 
phase). Acute local inflammation causes similar changes, but the 
diminution in the number of leucocytes also largely affects the coarsely 
granular cells, whereas the after increase is mainly in the finely 
granular. Hankin noticed that the blood clots more readily when the 
coarsely granular cell is scanty; this may explain the more ready 
clotting of blood in inflammatory conditions. 


The blood possesses, in the presence of free oxygen, a certain power of 
producing oxidation in readily oxidisable substances, which may be added to 
it, such as salicylaldehyde.® This property it shares with some of the 
tissues (spleen, liver, lung, thyroid, kidney, thymus), while other tissues 
show no such tendency (muscle, brain, pancreas). The oxidation power is 
greater in young subjects than in the adult.!° On the other hand, the blood 
contains a substance or substances (“reducing substances” of Pfliiger) which 
greedily appropriate any free oxygen which may be present in the plasma, 


1 Oliver, Zoc. cit., p. 1705. 

? Garrod, Med.-Chir. Trans., London, vol. lxxv. p. 191. 

8 Lancet, London, 1878, vol. ii. p. 822. 

4 Zischr. f. physiol. Chem., Strassburg, Bd. xvi. S. 505. See also G. Hoppe-Seyler, 
ibid., 1896, Bd. xxi. S. 461, and Winternitz, ibid., S. 468. 

® Lovibond, ‘‘ Measurement of Light and Colour Sensations.” 

§ For more complete details of the method see Oliver, Joc. cit., pp. 1699-1703. 

7 Sherrington, Proc. Roy. Soc. London, 1894, vol. lv. ; Kanthack and Hardy, Journ. 
Physiol., Cambridge and London, 1894, vol. xvii. p. 81. The earlier literature is given by 
Sherrington. 

8 “Studien z. Phys. u. Path. d. Blutes,” Jena, 1892. 

® Salkowski, Zischr. f. physiol. Chem., Strassburg, 1882, Bd. vii. S. 115 ; Centradbl. f. 
d. med. Wissensch., Berlin, 1892, Bd. xxx. S. 489. 

1 Abelous and Biarnes, Arch. de physiol. norm. et path., Paris, 1895, pp. 195 and 239. 


GENERAL COMPOSITION. 153 


and are even capable of abstracting the oxygen which is combined with 
hemoglobin, so that arterial blood rapidly becomes converted into venous 
blood, when it is not exposed to the access of fresh oxygen. It is not known 
upon what substance or substances these properties depend, but it is prob- 
able that it is a function of the protoplasm of cells, and, in the case of the 
blood, it may be due to the protoplasm of the white corpuscles. 


General composition.—The general composition of blood and the 
relative distribution of its constituents in the corpuscles and plasma 
respectively is illustrated in the accompanying tables from C. Schmidt ! 
and Bunge. ? 


Venous Blood of a Man, et. 25, sp. gr. 1:0599 (C. Schmidt). 
In 1000 grms. blood corpuscles (sp. gr. 1-0886)— 


Water : : ; ‘ :; : : 681°63 
Substances not vaporising at 120° C, : : ‘ 318°37 
Hemoglobin and other proteid substances : ; 311°09 
Inorganic substances— 
Chlorine : : ' ; 1-750 
Sulphuric acid. ; ; : 0-061 
Phosphoric acid . ; : ‘ 1°355 
Potassium : ‘ : : 3091 
Sodium ; : : ; 0-470 
Phosph. ime. : : d 0-094 
Phosphate magnesia : ; : 0-060 
Oxygen . 3 : ; : 0-401 
Total of inorganic constituents (exclusive of iron) ——— 7282 
In 1000 grms. plasma (sp. gr. 1°0312)— 
Water : : : . : : : 901°51 
Substances not vaporising at 120° C. : : ; 98°49 
Fibrin . : : : : : : 8-06 
Other proteids and organic substances . i : 81:92 
Inorganic substances— 
Chlorine f : ; 2 3°D36 
Sulphuric acid . é : ; 0-129 
Phosphoric acid . : ; : 0-145 
Potassium : . : ‘ 0-314 
Sodium . , : : ; 3°410 
Phosphate lime . : : ; 0:298 
Phosphate magnesia : : , 0.218 
Oxygen . : ; 0-455 


8505 


Total of inorganic constituents — 


In this estimation the phosphoric acid is probably too high, being 
increased in the process of calciming by the phosphorus in the lecithin. 
Sertoli? by eliminating this error, obtained only 0:025 grm. phosphoric 
acid per 1000 grms. ox serum, equivalent to only 0-005 per cent. hydro- 
disodic phosphate (Na,HPO,). 

It is clear from the following table that there are considerable 
differences in the composition of the whole blood and of its parts in 


1 “¢Charakter. der epid. Cholera,” Leipzig, 1850. 

2 Ztschr. f. Biol., Miinchen, 1876, Bd. xii. S. 191; and ‘‘Physiol. and Pathol. 
Chemistry,” trans. by Wooldridge, 1890, p. 245. 

3 Sertoli in Hoppe-Seyler’s Med. Chem. Untersuch.. Berlin, 1868, 8. 352. See also 
Miroczkowski, Centralbl. f. d. med. Wéissensch., Berlin, 1878, S. 353, who obtained in calf 
serum, 0°018 ; in sheep serum, 0.0092 and 0:0064 ; and in dog serum, 0°0083 parts 
Na, HPO, per 100 serum. 


154 THE BLOOD. 


different species of animals. In most animals the blood corpuscles have 
a relatively large proportion of potash salts and phosphates, whereas 
the preponderating salt in the serum is sodium chloride. In the bullock, 
however, this salt also oceurs in large amount in the corpuscles. 


Defibrinated Blood of Pig, Horse, and Bullock (Bunge). 


In 1000 GrMs. CORPUSCLES. In 1000 Gros. SERUM. 

Pig. Horse. | Bullock. Pig. Horse. | Bullock.’ 
Water . : é ! a Mots) 608°9 599°9 919°6 896°6 913°3 
Solids. ; : : . | 367°9 391°1 400°1 80°4 103°4 86°7 
Proteids, including hemoglobin | 347°1 Bi 3 387°8 67°7 nee 73°2 
Other organic substances eee 20 (5) 5 5°6 
Inorganic substances. é 89 sa 4°8 et Sab 78) 
ie 5543 4-92 0°747 0°273 0°27 0-254 
Na,O 27092 4°272 4°43 4°351 
CaO me 0°136 0°126 
MgO 0°158 0°017 0°038 0°045, 
Fe,0, oo onan i Ae Jf Si ies 0-011 
Cl : ; ‘ ; ; 1°504 1°93 1°635 3°611 3°75 3°717 
Ee Oe : : : sss) OGM | eo 0°703 07188 ae 0°266 


In the pig’s blood analysed, there were, in 1000 parts, 436°8 corpuscles, and 
563°2 serum. 

In the horse’s blood analysed, there were, in 1000 parts, 531°5 corpuscles, 
and 468°5 serum. 

In the bullock’s blood analysed, there were, in 1000 parts, 318°7 corpuscles, 
and 681°3 serum. 


A. Schmidt, in conjunction with his pupils,! got the following results 
from analyses of human blood obtained by venesection. 


ere ick Amount of Na, K, and Cl, in 
mou ; 7 
Percentage Specific | Dry Besiane ‘LOD guia: ( Waxeaaca 
Amount. Gravity. | “in 100 
SEES, Na. K. Cl. 
= =| ee ee | 
Serum ; ‘ - | 52°120 1028°3 9-709 0344 0°02 0°353 
Corpuscles : : 47-880 ae 35°458 0°282 0°307 
Total blood : | et 1060°7 lee Za 971 0°185 0:182 0°259 


Gases of the blood.—Arterial blood of the dog contains from 15 to 
25 vols. per cent. oxygen (at 0° C. and 760 mm. pressure), 25 to 40 car- 
bonie anhydride, and about 1°8 vols. per cent. nitrogen. Venous blood 
of the same animal contains from 5 to 15 vols. per cent. oxygen, 38 to 
52 carbonic anhydride, and also about 1°8 vols. per cent. nitrogen.” The 
proportions of these gases and the manner in which they are combined 
with constituents of the corpuscles and plasma is discussed elsewhere.* 


! Arronet, Diss., Dorpat, 1887 ; Warnach, Diss., Dorpat, 1888. 

2 Schoffer, Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1860, Bd. xli. S. 589; 
Sezelkow, zbid., 1862, Bd. xlv. S. 171; Pfliiger, Arch. f. d. ges. Physiol., Bonn, 1868, Bd. 
i. S./ 275: 

3 See ‘‘ Chemistry of Respiration.” 


ota enadin le be OD EE 


COMPOSITION OF RED CORPUSCLES. 155 


The red corpuscles.—These consist of a delicate external envelope 
enclosing coloured fluid contents. In all vertebrates below mammals 
they contain a nucleus, the chief chemical constituent of which is 
nuclein (see p. 65). 

The organic matter in one hundred parts of dried red corpuscles . 
consists of :2— 


HuMAN BLoop. | 
Doc's Bioop. Goose's BuLoop. 
Il. I | 
Proteids and | 
nuclein . - | 12°24 5°10 255 36°11 
Hemoglobin. 86°79 94°30 | 86°50 | 62°65 
lecithin . . 0°72 0°35 0°59 0°46 
| | 
Cholesterin ai 0°25 0°25 | 0°36 0.48 


| 


Goose’s blood was taken as an instance of one in which nucleated 
red corpuscles are present; the higher percentage of proteids apparent 
in this is due to the included nuclein. 

The mineral constituents of the red corpuscles vary greatly in 
relative quantity in different species of animals. Thus potassium con- 
stitutes 40°89 per cent. of the total ash of human red corpuscles, and 
sodium only 9°71, whereas in the dog the percentage of potassium is 
6:07, and of sodium 36:17 (C. Schmidt). 

The remarkable excess of potassium over sodium salts is the opposite to 
their relative proportion in plasma. 

The chief organic constituent of the corpuscles, hemoglobin, will be 
considered in a separate article. The other organic constituents consist 
of nucleo-proteid, lecithin, and cholesterin. 

The nucleo-proteid of the red corpusele—W ooldridge’s* method for 
obtaining the nucleo-proteid consists in centrifugalising defibrinated 
blood repeatedly with a 1 per cent. sodium chloride solution until all 
the serum is washed away. The red corpuscles are then laked by 
the addition of water, and the mixture is shaken with a little ether, 
to assist the solution; the white corpuscles are allowed to settle, 
or removed by the centrifuge. To the clear but highly coloured 
decanted fluid a little 1 per cent. solution of acid sodium sulphate is 
added. This causes a considerable precipitate of nucleo-proteid, which 
is chiefly derived from the red corpuscles, but a small part of which 
may come from the white corpuscles and blood platelets. 

The material thus obtained was shown by Kiihne,* who used a rather 
different method of separating it, to possess fibrino-plastic properties. It 
was further examined by Halliburton and Friend,’ who found that it was 


1 Schiifer in Quain’s ‘‘ Anatomy,” 10th edition, 1893, vol. i. pt. 2, p. 210. 

2 Hoppe- -Seyler and Jiidell, Med. Chem. Untersuch., ” Berlin, 1866, Heft 3. Manasse, 
Zischr. f. physiol. Chem., Strassburg, Bd. xiv. S. 452, gives the following percentages— 
Lecithin, 1-687; Cholesterin, 0°151. 

8 Arch, I: Physiol., Leipzig, 1881, S. 387. 

4“ Tehrbuch,” S. 193. 

5 Journ. Physiol., Cambridge and London, 1886, vol. x. p. 532. 


156 THE BLOOD. 


identical in properties with what had been called by Halliburton cell 
globulin-8 (see p. 82). When cell globulin-8 was discovered to be a 
nucleo-proteid, this also was found to be of the same nature.t It can 
also be prepared from the red corpuscles by Wooldridge’s acetic-acid 
method, or, provided the corpuscles are well caked together by the action 
of an efficient centrifuge, by the sodium-chloride method of Halliburton. 
In these experiments the colourless corpuscles may be got rid of by a 
‘previous injection of commercial peptone. 

In cats the percentage of phosphorus in the corpuscular nucleo-proteid 
is 0°68. It produces intravascular coagulation when a solution in 1 per 
cent. sodium carbonate is injected intravenously (Halliburton). 

The lecithin and cholesterin.— L. Hermann? and Hoppe-Seyler® 
described the phosphorus-containing organic constituent of the cor- 
puscle as protagon, a substance got in large quantities from medullated 
nerves, but subsequently it was recognised by Hoppe-Seyler* to be in 
reality lecithin, which is a decomposition product of protagon (see p. 83). 
Both lecithin and cholesterin are extracted from the corpuscles by ether, 
and are therefore either free or, at most, in very loose combination 
with the nucleo-proteid. 

The chemical composition of the white corpuscles has been 
already dealt with (p. 83). 

The blood platelets.—In spite of the large amount of research from 
the histological standpoint which has been carried out in relation to the 
blood platelets (Llutplattchen of Bizzozero), very little is known about 
their function or their chemical composition. According to Lowit,? 
they consist chiefly of a globulin, and play an important part in 
fibrin formation. As the result of microchemical work, Lilienfeld ® 
considers that they consist of nucleo-proteid. 

Lowit states that they are not to be seen in the circulating blood,’ 
and regards them as being produced partly from the white corpuscles, 
partly from globulins of the plasma, after withdrawal of the blood. 
They can, however, be seen within capillary blood vessels which have just 
been removed from animals, and in which the blood is still fluid. 
Mosen failed to find them in lymph.® 

Their number in the blood has been variously estimated at from 
180,000 to over 600,000 per c.mm.!° 


BLoop PLASMA. 


The methods of obtaining plasma from blood, by preventing coagula- 
tion and allowing the corpuscles to subside, have already been given. 
Obtained thus from a suspended vein or from a cooled vessel, plasma 


1 Halliburton, Journ. Physiol., Cambridge and London, 1895, vol. xviii. p. 306. 

2 Arch. f. Anat. u. Physiol., Leipzig, 1866, S. 83. 

3 Med. Chem. Untersuch., Berlin, Heft 1, S. 140. 

4 Tbid., Heft 3. 

> Arch. f. exper. Path. u. Pharmakol., Leipzig, 1888, Bd. xxiv. S. 188. 

6 Arch. f. Physiol., Leipzig, 1892, S. 115. 

? Virchow’s Archiv, 1889, Bd. exvii. S. 545; and ‘“‘Studien z. Phys. u. Path. d. Blutes 
u. d. Lymphe,” Jena, 1892. 

8 Osler, Proc. Roy. Soc. London, 1874, No. 183. This observation I can entirely confirm. 
9 Arch. f. Physiol., Leipzig, 1893, 8S. 352. See also Druebin, 1892, ibid., Suppl., S. 
Zales 

10 See on this subject, Muir, Journ. Anat. and Physiol., London, 1891, vol. xxi. ; also 
Brodie and Russell, Jowrn. Physiol., 1897, vol. xxi. p. 390, who give reasons for regarding 
the higher number as more correct. Probably, however, the number varies greatly. 


INORGANIC SUBSTANCES. 157 


is a clear yellowish liquid of alkaline reaction and sp. gr. about 1027-1031. 
It contains about 90 per cent. of water, holding various organic and 
inorganic substances in solution. With the exception of certain proteids, 
the constituents of plasma are identical with those of serum, in which 


‘ they are more readily studied. 


Inorganic substances.—Plasma consists to about 90 per cent. of 
water. The inorganic salts occur to the amount of about 0°8 per cent. 
The principal is chloride of sodium. This can be crystallised out from 
plasma after inspissation. According to the analyses of C. Schmidt, it 
is present to the extent of 0°55 per cent. Carbonate of soda is probably 
the next most abundant salt, although its exact amount cannot be stated. 
It is to this salt that plasma mainly owes its alkalinity and its power of 
absorbing carbonic acid. Although it is not possible to state definitely 
in what manner the acids and bases of the plasma are distributed, it 
appears probable that, besides these two salts, chloride of potassium, 
sulphate of potassium, phosphate of calcium, phosphate of sodium, and 
phosphate of magnesium, and probably chloride of calcium, occur ! in 
small amounts. ‘Traces of a fluoride have also been found.’ 

Gases.—The gases of plasma have not been satisfactorily investi- 
gated. They are probably not very different from those of serum, 
which in the dog consist of from 43 to 57 vols. of carbonic anhydride, 
2°25 of nitrogen, and 0°25 of oxygen. The oxygen and nitrogen are 
probably simply dissolved in the plasma, but the carbonic anhydride 
is present in far too great an amount for this to be the case, since 
not more than 2 or 5 vols. per cent. of this gas could be dissolved. The 
remaining amount must therefore be in chemical combination. This can 
only be with soda, as carbonate and bicarbonate; for other bases are 
present in too small amount in plasma to be taken into serious considera- 
tion. This statement is also true for alkaline phosphates, although in 
the corpuscles, in which they are present in considerable quantity, they 
may play an important part in fixing CO, (Bunge), as shown by the. 
following equation :— 


Na,HPO,+H,CO,=H,PO,+NaHCo,, 


Some of the CO, may be combined with proteid,* but this can only be 
very little. As a matter of fact, Bunge calculates that, after allowing 
for the amount of soda required to saturate the only strong mineral acid 
of the plasma (hydrochloric), there is enough left to fix 63 vols. per cent. 
of CO, as carbonate, and an equal additional amount as bicarbonate, 
which is far more than the amount of CO, actually present.? 

Organic constituents of blood plasma.—The organic constituents 
of plasma may be divided into proteids and non-proteids, and the latter 
into nitrogenous and non-nitrogenous. 

Non-nitrogenous organic substances found in plasma.—These 
consist of carbohydrates and fats; and, in addition, there are present 
small quantities of a lipochrome, of cholesterin, and probably of sarco- 
lactic acid. 

Carbohydrates of plasma—Three carbohydrates have been described 

1 Pribram, Abhandl. d. math.-phys. Cl. d. k. Sachs. Gesellsch. d. Wissensch., Math.-phys. 
Klasse, 1871, Bd. xxiii. S. 279 ; and in Arb. a. d. physiol. Anst. zu Leipzig, 1871, p. 63. 

?Tammann, Ztschr. f. physiol. Chem., Strassburg, 1888, Bd. xii. S. 325. 

° Bunge, op. cit., S. 286. 

4 Sertoli, Hoppe-Seyler's Med. Chem. Untersuch., Berlin, 1868, Heft 3, S. 350. 

5 Op. cit., S. 286. 


158 THE BLOOD. 


in plasma, namely—(1) glycogen; (2) an animal gum; (5) dextrose or 
Eee sugar. 

Gly Glycogen.—Vhere seeins to be no doubt that traces of glycogen can 
be Baie from fresh blood. Some is said to occur free in plasma, but 
if so it is probably derived from intermixed or disintegrated leucocytes, 
which can be shown by histochemical reaction to contain it.1 Kaufmann 
finds the amount of glycogen in blood to be greatly increased (from 0°025 

‘to 0°59 per litre) by removal of the pancreas.” 

2. Animal gum. —Freund® has obtained from blood a carbohydrate 
substance, resembling that described by Landwehr under the above name, 
It has the formula (C,H,,O,),, and is converted by boiling with dilute 
mineral acids into a substance (sugar) which reduces Fehling’s solution, 
but is not fermentable, nor is it rotatory for polarised ight. Four litres of 
ox blood yielded 0:82 grins. of the gum, giving a percentage amount of 0:02. 

3. Dextrose.—This is a constant constituent of plasma, whatever the 
nature of the diet, and even in starving animals.* It occurs in man to 
the amount of about 0°12 per cent. of the blood, in the dog from 0:11 
to 0-15 per cent. (or a little over 1 per 1000).2 It is present in 
nearly equal amount in blood from all parts, except in the blood of the 
portal vein, during digestion of carbohydrate-containing foods, where 
it is markedly increased. In the blood of the hepatic veins, in the 
intervals of digestion, the amount was stated by Bernard to be some- 
what greater than in the portal vein, or in the blood of the general cir- 
culation ; but this difference has not been found by Pavy and most other 
observers, although the statement has of late been reaftirmed by Seegen.® 

Bernard’ obtained a larger amount of sugar from arterial than from 
venous blood, and Seegen has in some instances obtained a similar 
result. Chauveau,$ and Chauveau and Kaufmann,® have also published 
analyses, which seem to show a disappearance of sugar after passing 
the capillaries. But the differences observed have not been constant, 
and are in any case so small as to lie within the range of experimental 
error. As the result of eleven experiments, Pavy finds the sugar in 
arterial blood to exceed that in venous by only 0:005 parts per 1000; 
and he concludes that no appreciable difference exists between the two.!® 

1H. A. Schafer, ‘‘A Course of Practical Histology,’ London, 1876, p. 39; Salomon, 
Deutsche med. Wehnschr., Leipzig, 1877, S. 92 and 421; Arch. f. Physiol., Leipzig, 1878 ; 
Centralbl. f. Physiol., Leipzig u. Wien, 1892, Bd. vi. S. 512; Ehrlich, Ztschr. f. klin. Med., 
Berlin, 1883, Bd. vi. S. 40 ; Gabritschewsky, Arch. f. exper. Path. u. Pharmakol., Leipzig, 
1891, Bd. xxviii. 8. 272; Huppert, Centralbl. f. Physiol., Leipzig u. Wien, 1892, No. 
14, 8S. 394 (Huppert found more in dog’s blood than in the blood of herbivora) ; Hoppe- 
Seyler, Ztschr. f. physiol. Chem., Strassburg, 1894, Bd. xviii. S. 144. 

2 Compt. rend. Acad. d. sc., Paris, 1895, tome cxx. p. 567. 

3 Centralbl. f. Physiol., Leipzig u. Wien, 1892, Bd. vi. S. 345. 

4 Cl. Bernard, Arch. gén. de méd., Paris, 1848, tome xviii. p. 303; Pavy, Phil. Trans., 
London, 1860; v. Mering, Arch. 7. Physiol., Leipzig, 1877, 8. 379; Otto, Arch. f. d. ges. 
Physiol., Bonn, 1885, Bd. xxxv. S. 467; Pickardt, Zéschr. f. ph pee Chem., Strassburg, 
Bd. xvii. S. 217 ; Miura, Zischr. f. Biol., Miinchen, Bd. xxxii. 8. 25 

5 Pavy, ‘‘ Physiology of the Carbohydrates, 5 1894, p- 161. 

6 Arch. f. d. ges. Physiol., Bonn, 1884, Bd. xxxiv. S. 388, and 1885, Bd. xxxvii. S. 
348; Centralbl. f. Physiol., Leipzig u. Wien, 1893, No. 12; “ Zuckerbildung im Thier- 
korper,” 1890. 

* Compt. rend. Acad. d. sc., Paris, tome 1xxxiii. p. 373, and ‘‘ Lecons sur le Diabete,” 1877. 

8 Tbid., 1856, tome xliii. p. 1008. 

9 Tbid., 1886, tome cil. p. 974. 

10 Pavy, Proc. Roy. Soc. London, 1877, vol. xxvi. p. 346; ‘On Certain Points connected 
with Diabetes,” London, 1878 " Physiolog y of the Carbohydrates,” pp- 170-171. This 
is also apparently admitted he Seegen (‘‘ La Glycogenie Animale,” Paris, 1890, p. 100), 


although his theory of the production of energy requires that there should be a diminution 
in the amount of sugar in venous blood, 


NON-NITROGENOUS SUBSTANCES IN PLASMA. 159 


Apart from these somewhat doubtful differences in blood from different 
parts, the amount in the blood remains almost constant, whatever the char- 
acter of the food, and even during starvation. The amount is somewhat in- 
creased as the result of heemorrhage,a result due either to accession of lymph 
(which contains a larger proportion of sugar than does blood), or to the 
operation, through the agency of the nervous system, causing an increased 
production of sugar from the liver-glycogen. If the amount of dextrose in 
the blood be artificially increased to more than about 0°25 per cent. the excess 
passes off by the urine. The amount is increased in diabetes, whether this be 
the result of the sugar puncture, of removal of pancreas, or of disease! 
but even under these circumstances does not rise above 0°48 per cent. 

Fats.—These are present in plasma in small but variable quantity 
(0-2 to 05 or even | per cent.)? being most abundant after a meal 
containing much fat. The plasma or serum may then be milky from 
admixture with the fat-containing chyle. They are composed of the 
usual glycerides of fatty acids (palmitin, stearin, and olein). A small 
amount, 0°05—0'1 per cent., is in the form of soap.? It has been stated 4 
that there is a greater amount of fat (ether extract) in arterial than in 
venous blood, but this result is shown by Rohmann and Miihsam® to 
have been probably due to an error brought about by venous congestion, 
which affects the proportion of all the solids of blood as compared with 
the water. The fatty acids appear also to be partly in combination with 
cholesterin, forming cholesterin-esters, of which two have been separated 
by Hiirthle® in a crystalline form, namely, the olein and palmitin com- 
pounds, to the extent in horse serum of 0°08 and 0-06 per cent. respec- 
tively. Hiirthle further found that in the dog they were increased 
during inanition. The amount of cholesterm in serum or plasma is 
stated by Hoppe-Seyler to be about 0:05 gr. per 100 c.c. blood,’ and is 
probably mainly in the form of the fatty acid combinations just referred 
to, and not, as was formerly supposed, in the free condition (Hiirthle). 

Lipochrome.—The yellow-colouring matter of serum is a lipochrome 
soluble in amyl and also in ethylic alcohol, but insoluble in turpentine. 
Its absorption spectrum shows two ill-defined bands,° one at the F and 
the other between the F and G Frauenhofer lines (Plate un, Fig. 
24). It resembles the luteim of Kiihne. 

Lactic acid—The presence of sarcolactic acid as a regular con- 
stituent of normal blood plasma has been affirmed (0:017—0-054 per cent. 
in dogs).2 Salomon could only find it in blood from the dead body, not 
in that drawn during life,!° but Irisawa confirms its existence in fresh 
blood (dog), and states that it is present to some extent in the cor- 
puscles as well as in the plasma."t It is increased in blood which has 


1 Pavy, ‘‘On Certain Points connected with Diabetes’; Seegen, Wien. med. Wehnsehr., 
1886, S. 1561 and 1595. 

2 Rohrig, Abhandl. d. math.-phys. Cl. d. k. Sachs. Geselisch. d. Wissensch., 1874, S. 1, 
and Arb. a. d. physiol. Anst. zw Leipzig. 

3 Hoppe-Seyler, Zschr. f. physiol. Chem., Strassburg, Bd. viii. S. 503. 

4 Bornstein, Diss.. Breslau, 1887. 

5 Arch. f. d. ges. Physiol., Bonn, 1889, Bd. xlvi. S. 383. 

6 Zischr. f. physiol. Chem., Strassburg, 1896, Bd. xxi. S. 331. 

7 Med. Chem. Uniersuch., Berlin, 1866, S. 145. 

8 Krukenberg, Sitzwngsb.d. Jenaisch. Gesellsch.f. Med.u. Naturw., 1885, Suppl. Bd.xix.S. 25. 

* Gaglio (with Drechsel), Arch. f. Physiol., Leipzig, 1886, S. 400; Spiro, Zschr. f. 
physiol. Chem., Strassburg, 1887, Bd. i. S. 110; Berlinerblau (with Nencki), Arch. /f. 
exper. Path. u. Pharmakol., Leipzig, 1887, Bd. xxiii. 8. 333. ; 

0 Virchow’s Archiv, 1888, Bd. exiii. S. 356. 

1 Ztschr. f. physiol. Chem., Strassburg, 1893, Bd. xvii. S. 340. 


160 THE BLOOD. 


been perfused through the still living kidneys or lungs, or through the 
muscles of the lower limb, especially if inosit or glycogen or dextrose 
be added to the blood used for perfusion (Gaglio, Berlinerblau). It is 
also increased by intravenous injection of dextrose in blood circulating 
normally through the body. It appears to enter into combination with 
sodium hydrate, driving out CO,,? 

Non-proteid nitrogenous constituents of plasma.—The most im- 

‘portant of these are urea? (0°02-0-°05 per cent.), kreatin, kreatinine? 
and uric acid,* and occasionally hippuric acid.® Xanthine and hypo- 
xanthine are stated to be also present. Gréhant and Quinquand found 
the amount of urea in blood drawn from the splenic, portal, and hepatic 
veins to be slightly greater than im that taken from the carotid.? 
Lecithin occurs in small amount in plasma’ According to Marino- 
Zucco, neurine and glycero-phosphoric acid are also present in traces in 
the free state. There has also been described as a constant constituent, 
jecorin ®—a substance which reduces Fehling’s solution, but is soluble 
in ether and is not fermentable. It is stated to occur in considerably 
larger amount in venous than in arterial blood.! 

Ferments—Three ferments have been described as occurring in blood, 
namely— 

1. A diastatic ferment, producing the conversion of amyloids to sugar. 

2. A glycolytic ferment, producing the disappearance of sugar. 

3. A fat-splitting ferment (lipase)." 

4. A fibrin ferment (thrombin), or its precursor (prothrombin), pro- 
ducing the formation of fibrin from fibrmogen. The last will be con- 
sidered in connection with coagulation. 

Diastatie action—A ferment action, converting starch into dextrin 
and maltose, and ultimately into dextrose, has been obtaimed with 
blood and lymph by Rohmann ” and bial,’ and also by Hamburger,“ by 


1 Vaughan Harley, Arch. f. Physiol., Leipzig, 1894, S. 451. 

2Simon, Arch. f. Anat. u. Physiol., Leipzig, 1841, S. 454; I. Munk, Arch. f. d. ges. 
Physiol., Bonn, 1875, Bd. xi. S. 105; Schroder, Arch. f. exper. Path. u. Pharmakol., 
Leipzig, 1882, Bd. xv. S. 364; and 1885, Bd. xix. S. 373. Picard (Journ. de V'anat. et 
physiol. etc., Paris, 1881, p. 530) found the percentage of urea rather higher than this in 
the dog (0°09 to 0°13). 

3 Verdeil and Marcet found both kreatin and kreatinine (Journ. de pharm. et chim., 
Paris, 1851, tome xx. p. 89); Voit (Ztschr. f. Biol., Miinchen, 1868, S. 93) could find no 
kreatinine ; but Colls (Jowrn. Physiol., Cambridge and London, 1896, vol. xx. p. 107) 
obtained a small but definite quantity. 

4 Scherer and Strecker, quoted by Hoppe-Seyler (‘‘ Physiol. Chem.”’); Garrod, Med.- 
Chir. Trans., London, 1848, vol. xxxv. p. 83, and 1854, vol. xxxvii. p. 49. See also 
‘‘Nature and Treatment of Gout,” 1861; Abeles, Med. Jahrb., Wien, 1887, S. 479. On 
the other hand, v. Jaksch (Zischr. f. Heilk., 1890, Bd. xi. S. 415) could find no uric 
acid in the blood of healthy individuals (nine cases). 

5 Verdeil and Goldfuss, Compt. rend. Soc. de biol., Paris, 1850, tome il. p. 79. Meissner and 
Shepard (‘‘ Untersuch. ii. d. Ensteh. d. Hippurs.,” Hannover, 1866) were unable to find it. 

6 Halliburton, ‘‘Chem. Physiol.,” p. 251. 

7 Journ. de Vanat. et physiol. etc., Paris, 1884, p. 317. 

8 Hoppe-Seyler, Med. Chem. Untersuch., Berlin, 1869, 8. 551. 

® Baldi, Arch. f. Physiol., Leipzig, 1887, Suppl. Heft, S. 100; Henriques, Zéschr. f. 
physiol. Chem., Strassburg, Bd. xxiii. S. 244. 

10 Jacobsen, Centralbl. 7. Physiol., Leipzig u. Wien, 1892, S. 368. 

 Hanriot, Compt. rend. Soc. de biol., Paris, 1896, p. 925. 

LP Arch. f. d. ges. Physiol., Bonn, 1892, Bd. lii. 8. 157. 

13 Tbid., 1892, Bd. lii. S. 137; and Bd. liii. S. 156; Rohmann and Bial, Arch. f. 
d. ges. Physiol., Bonn, 1898, Bd. liv. S. 72; Bd. lv. S. 469. According to Lépine and 
Barral (Compt. rend. Acad. d. sc., Paris, 1893, tome exiii., pp. 118, 729, 1014, and exv. 
p- 304) sugar may be formed in blood on standing, at the expense of added peptone, as 
well as starch or glycogen ; but this was not confirmed by Bial. 

14 Thid., 1895, Bd. lx. S. 543. 


PROTEIDS OF PLASMA. 161 


mixing blood or serum with starch or glycogen solution, and keeping it 
at body temperature. Réhmann has shown that the diastatic change may 
occur in lymph within the vessels as well as im vitro. Cavazzani 
obtained most effect in blood taken from the portal vein! Tscherevkoff 
finds that the diastatic ferment is precipitated by excess of alcohol, and 
that its action is not destroyed by long standing under alcohol, nor by 
sodium oxalate.” 

Glycolytie action—It was noticed by Bernard*® that the sugar of 
blood diminished on standing in vitro. Pavy found that both the normal 
sugar and added sugar diminishes in blood on standing.* In any case, 
and without standing, it is difficult to recover the full amount from 
blood or serum, apparently owing to the fact that, in coagulating the 
proteids with a view to their removal, a part of the sugar is mechanically 
carried down or retained by them;® this fact may lead to very con- 
siderable experimental errors.6 Allowing, however, for such errors, it 
appears clear that there is some actual loss of sugar on standing both 
in blood? and in lymph or chyle.8 According to Seegen, the glycolytic 
action is active in the presence of chloroform, and is destroyed by a 
temperature of more than 54° C., in these respects resembling an enzyme. 
Lépine states that it is absent or diminished in activity in diabetes,® 
whether the result of disease or operation (removal of pancreas), and 
that a very active glycolysis occurs in perfusing blood through various 
organs (kidney, lower limbs).!° Arthus, on the other hand, denies the 
pre-existence of a glycolytic ferment in blood. He finds no glycolysis 
in oxalated blood, and thinks it probable that the ferment is formed 
from leucocytes during coagulation." Kraus finds that the glycolysis 
which occurs in blood on standing is accompanied by a splitting off of 
CO,, and is probably due therefore to oxidation.” 

Proteids of plasma.—The proteids of plasma are— 

1. One or more closely allied albumins (serum albumins). 

2. Two globulins, termed respectively serum globulin and fibrinogen. 

3. A nucleo-proteid or nucleo-proteids. 

Blood contains normally neither albumose nor peptones.!* All the 
proteids are completely precipitated by saturating plasma with ammo- 


1 Arch. per le sc. med., Torino, 1893, vol. xvii. p. 105. 

2 Arch. de physiol. norm. et path., Paris, 1895, p. 628. 

3 Compt. rend. Acad. d. sc., Paris, 1876, p. 1406. 

4 Proc. Roy. Soc. London, 1877, vol. xxvi. p. 346; and 1879, vol. xxvii. p. 520. See 
also ‘‘ Physiol. of Carbohydrates,” pp. 171-179. 

*>Rohmann, Centralbl. f. Physiol., Liepzig u. Wien, 1890, No.1; V. Harley, Journ. 
Physiol., Cambridge and London, 1891, vol. xii. p. 391; Pavy, Brit. Med. Journ., London, 
1896, vol. i. p. 453. 

6 Schenck, Arch. f. d. ges. Physiol., Bonn, 1890, Bd. xlvi. S. 607 ; 1891, Bd. xlvii. 
S. 621. For a method whereby such errors may be largely avoided see E. Waymouth 
Reid, Journ. Physiol., Cambridge and London, 1896, vol. xx. p. 316. 

7 Rohmann, Joc. cit. ; Harley, loc. cit. ; Seegen, Wien. klin. Wehnschr., 1892, Nos. 14 
and 15. 

8 Lépine, Compt. rend. Acad. d. sc., Paris, 1890, tome cx. p. 742; Lépine and Barral, 
tbid., 1890, tome cx. p. 134; ibid., 1891, tome exii. pp. 411, 604, 1185, 1414; and 
tome exiii. p. 118. 

® Lépine and Metroz, ibid., 1893, tome exvii. p. 154. 

10 Lépine and Barral, Joc. cit. 

Arch. de physiol. norm. et path., Paris, 1892, p. 337 ; Compt. rend. Acad. d. sc., 
Paris, 1892, tome exiv. p. 605. : 

2 Zischr. f. klin. Med., Berlin, 1892, Bd. xxi. S. 315. See also R6hmann and Spitzer, 
Ber. d. deutsch. chem. Geselisch., Berlin, Bd. xxviii.; and Spitzer, Arch. f. d. ges. Physiol., 
Bonn, 1895, Bd. lx. 

18 Halliburton and Colls, Journ. Path. and Bacteriol., Edin. and London, 1895, p. 295. 


VOL. 1.——FL 


162 THE BLOOD. 


nium sulphate. The globulins and nucleo-proteids are completely pre- 
cipitated by half-saturation with ammonium sulphate, or by complete 
saturation with magnesium sulphate; whilst fibrinogen is precipitated - 
by half-saturating plasma with chloride of sodium (probably some nucleo- 
proteid is carried down with it). Upon these differences of solubility in 
solutions of neutral salts the separation of the blood-proteids one from 
. another depends. 

The proportion of globulin to albumin globulin is known as the “ proteid 

albumin 

quotient” ; it varies in different animals and in the same species of animal 
under different conditions.!_ For the same individual it is almost constant in 
the blood serum, lymph, and serous transudations, although the absolute 
amount of proteid in these may vary greatly.” 

The annexed table * shows the total and relative amounts of the proteids 
in the serum of different animals. The numbers are taken from different 
sources ; the first four from Hammarsten.* 

They are obtained—(a) the total proteids, by weighing the alcohol 
precipitate; (b) the globulin, by separating off the magnesium sulphate 
precipitate, re-dissolving this and weighing its alcohol precipitate; (c) the 
albumins, by taking the difference between these two results. (b) includes, 
besides serum globulin, a globulin formed from fibrinogen in coagulation, and 
also the nucleo-proteids of plasma, but both of these are in very small amount. 


|(a) Total Proteids| (%) Globulins (c) Albumins 

} per Cent. per Cent. per Cent. 
Man 7°62 | 3°10 4°52 
Horse 7°25 4°56 2.69 
Ox. 7°50 4°17 3:33 
Rabbit 6°22 179 4°43 
Pigeon 5°01 1°32 3°69 
Hen 4°14 2°90 1°24 
Tortoise 4°76 2°82 1°94 
Lizard : : : : 5°16 3°33 1°83 
Terrapin . : : au | 5°35 4°66 0°69 
Snake : : : , 5°32 4°95 0:37 
Frog . : : : j 2°54 2°18 0°36 
Toad. : : : EM B22 1°82 | 1°40 
Newt : : : ‘ Sy! 3°31 | 0°43 
Eel . ; , : 6°73 5°28 1°45 
Dog-fish_ . : : ; 1°62 1-17 | 0°45 

| 


The most noteworthy feature shown in these figures is the relatively 
small amount of albumins present in the serum of cold-blooded animals 
as compared with the globulins. It has been stated that the albumins 
proportionately diminish in starved animals,> but other investigators 
have failed to confirm this conclusion.® 


1 Compare Frassineto, Arch. ital. de biol., Turin, 1895, vol. xxiv. p. 457; Paulesco, 
Arch. de physiol. norm. et path., Paris, 1897, p. 21; W. Engel, Arch. f. Hyg., Miinchen 
u. Leipzig (4), Bd. xxviii. S. 334. 

2 Salvioli, Arch. f. Physiol., Leipzig, 1881, S. 269; Hoffmann, Arch. f. exper. Path. u. 
Pharmakol., Leipzig, 1882, Bd. xvi. 8S. 133. 

3 Halliburton, Jowrn. Physiol., Cambridge and London, 1878, vol. vii. p. 321. 

4 Arch. f. d. ges. Physiol., Bonn, 1878, Bd. xvii. S. 413. 

> Tiegel, zbid., 1880, Bd. xxiii. S. 278 ; Burckhardt, Arch. f. exper. Path. u. Pharmakol., 
Leipzig, 1883, Bd. xvi. S. 322. 

§ Salvioli, Arch. f. Physiol., Leipzig, 1881, S. 269; Howell, John Hopkins Univ. 
Stud. biol. lab., Baltimore, vol. iii. p. 49; Rubbrecht, 7rav. du lab. de L. Fredericg 
tome v. p. 121. 


PROTEIDS OF PLASMA. 163 


Albumins of blood plasma.—The albumins of plasma are also found 
in the serum after coagulation of blood, and hence they have been 
termed serum albumins. They remain in plasma or serum after half- 
saturating it with ammonium sulphate, 7.e. by mixing it with an equal 
amount of saturated ammonium sulphate solution, or after entirely 
saturating it with magnesium sulphate. 

The precipitated clobulins and nucleo-proteid are removed by filtra- 
tion, and the filtrate dialys sed to remove the salts. The solution which 
remains contains only the albumins; they can be precipitated from it by 
saturation with ammonium sulphate or by sodio-magnesium sulphate. 
According to Giirber, they can be obtained in a erystalline form by 
adding ammonium sulph ate just sufficient to produce precipitation and 
allowing the fluid to stand exposed to the air. 

The material obtained in these ways constitutes what has usually 
been called serum albumin (serine), but, as Halliburton has shown? it is 
really a mixture of three separate albumins, which he has termed 
respectively «, (3, y. These differ from one another in their temperature 
Cp heat coagulation ; g-albumin coagulates at 72°-75° C.; 6-albumin at 

Se on and y-albumin at 83° “86° C. In the plasma. of horse, ox, 
a oe blood, «-albumin is absent, but the other two are present; in 
man, and all other mammals and birds investigated by Halliburton, all 
three were present; but in reptiles, amphibia, and fishes investigated, 
#-albumin was usually the only one found. 


The crystals of serum albumin which were obtained by Giirber from the 
serum of horse’s blood were hexagonal prisms with one pyramidal end, 
and were doubly refracting; some of them were as much as 1 em. long. 
Their elementary composition was C, 53:1; H, 71; N, 15:9; S, 1:9, 
0-22; and ash, 0°22 per cent. Dissolved in water and the excess of 
ammonium sulphate removed by dialysis, the solution had a heat coagulation 
temperature of 51° to 53°, and a specific rotation for yellow light of —61°.4 


The globulins of blood plasma.—The globulins of blood plasma con- 
sist of serum globulin and fibrinogen. Serum globulin (paraglobulin, 
Kiihne; fibrino-plastic substance, A. Schmidt) has a heat coagulation 
temperature of 75° C., which is almost constant in all animals in 
which it has been examined. The amount to which it is contained 
in plasma is represented by the figures in the second column of the 
table on p.162. It will be seen from this, that in man it constitutes about 
three parts per cent. of the total serum. It is precipitated from serum by 
half-saturation with ammonium sulphate,’ and also by complete saturation 
with magnesium sulphate, sodium chloride, and some other neutral salts 
which do not precipitate the albumins; also, but less completely, by dilut- 
ing the serum with water (fifteen times) and passing CO, through it, or by 


1 Sitzungsb. d. phys.-med. Gesellsch. zu Wiirzburg, 1894, S. 143. 

2 Journ. Physiol., Cambridge and London, vol. v. p. 152. 

3 Tn the slider terrapin (Howell, John Hopkins Univ. Stud. biol. lab., Baltimore, vol. 
iii. p. 49) the albumin present is apparently of the f# variety, coagulating at 77° to 80°, 
and in the eel and dog-fish this variety was also found by Halliburton (Journ. Phu ysiol., 
Cambridge and London, vol. vil. p. 320). 

4 Michel (with Giirber), Verhandl. d. phys.-med. Geselisch. zu Wiirzburg, 1895, N. F., 
Bd) xxix. No: 3: 

5 Kauder (Arch. f. exper. Path. u. Pharmakol., Leipzig, 1886, Bd. xx. S. 411) found 
that solutions of ammonium sulphate stronger than 24 per cent. completely precipitated 
serum globulin; above 33°5 per cent. some of the serum albumin also comes down. 
half-saturated solution contains about 26 per cent. 


164 THE BLOOD. 


diluting with water and neutralising it with dilute acetic acid (in excess 
of which it easily dissolves). Like other globulins, it requires the 
presence of a certain amount of salts, or weak alkah, to be dissolved in 
water; it 1s therefore precipitated by dialysis or by sufficient dilution 
of its solutions in salts or in serum, even without the addition of an 
acid. 

Fibrinogen.—This is the substance to which the plasma of the blood 
especially owes its property of so-called spontaneous coagulability ; which 
led to the term “ coagulable lymph” being applied to it by older writers.t 
It is precipitated from plasma along with serum globulin, by saturation 
with magnesium sulphate or sodium chloride; the precipitation of 
mixed globulins so obtained (the plasmine of Denis) forms a coagulable 
liquid, on dissolving it in a more dilute solution of salt. Fibrinogen is 
entirely precipitated from plasma, or any other fluid containing it, by 
half-saturation with sodium chloride;? it can be re-dissolved in water 
with the aid of the salt adhering to it, reprecipitated by half-saturation, 
and so on until it is obtained in a condition which may be regarded as 
approaching purity. But in contact with the salt solution it oradually 
loses its solubility, and every time that it is precipitated less of the 
precipitate redissolves on adding water; the material which forms and 
which remains undissolved in the dilute solution of salt resembles 
fibrin in many physical and chemical characters, but is not similarly 

rapidly swollen by dilute acids; it may be termed para-fibrinogen or 
pseudo-fibrin. Fibrinogen dissolves also in dilute alkali, even in the 
absence of neutral salts» its alkaline solutions are clear, but its solutions 
in neutral salt solutions are opalescent. It is precipitated from the 
solution in weak alkali by careful neutralisation with acetic acid, and from 
solutions in neutral salt solutions by slightly acidulating with the same 
acid, but it is readily soluble in excess of the acid. The temperature o 
heat coagulation of fibrinc gen in salt solution is between 52° and 55°; 
but the whole of the dissolved proteid is not thrown down at ti 
temperature ; a small amount remains in solution, and is not coagulated 
until the temperature of 65° C. is attained. According to Hammarsten,* 
this is due to the splitting of the fibrinogen, under the influence of 
heat, into coagulated fibrinogen and a elobulin, which is coagulated at 
the higher temperature. If. fibrinogen which has been obtaimed from 
blood plasma by the above method of half-saturation with NaCl, and 
purified by repeated re-solution and re-precipitation with acetic acid, be 
dissolved in water rendered faintly alkaline by NaHO, it gives a 
coagulum-like precipitate (if sufficiently concentrated) a short time after 
the addition of a lime salt. The coagulum resembles fibrin in many 
_ respects, but, according to Hammarsten, it is not true fibrin, but a 
combination of fibrinogen with lime.® 


' Houlston, Diss. Med. Inaug., ‘‘ de Inflammatione,” pp. 11, 12, 14, Lugd. Bat., 1767. 
See Hewson’s Works, Introduction, p. xxxvii, edited by G. Gulliver, London, printed for 
the Sydenham Society, 1846. 

? Hammarsten, Arch. f. d. ges. Physiol., Bonn, 1879, Bd. xix. S. 563. 

2 Hammarsten, tbid., 1880, Bd. xxii. S. 431. 

4 [bid., 1879, Bd. xix. S. 568. 

° Hammarsten, Ztschr. f. physiol. Chem., Strassburg, 1896, Bd. xxii. S. 333. It is 
unnecessary to add any ferment or nucleo- proteid to the solution to produce the result, but 
there is no doubt that nucleo-proteid may be present along with the fibrinogen. It was 
shown by Lilienfeld (Ztschr. f. physiol. Chem., Strassburg, 1895, Bd. xx. S. 89) that 
fibrinogen prepared by Hammarsten’s method contains nuclein ; from this he inferred that 
it is anucleo-proteid, and not a globulin. But the amount of nuclein present is not sufficient 


io 


PROTEIDS OF PLASMA. 165 


As just stated, fibrinogen is precipitated from plasma, and from 
its solutions in neutral salt solution, or dilute alkalies, by the addition of 
dilute acetic acid, even in slight excess. This precipitate has been 
termed “thrombosin ” by Lilienfeld,! who regards it as due to a splitting 
of the fibrinogen under the influence of the acid into this substance and 
an albumose, but it has not been shown that it possesses any properties 
differing from fibrinogen. 


From what has been stated, it will be seen that it is improbable that the 
material which is obtained from plasma, under the name of fibrinogen, is a 
simple substance. It is probably either a mixture, or a loose combination, of 
at least three substances, namely— 

1. Fibrinogen proper, coagulating at 56° C. 

2. The globulin described by Hammarsten, and termed jibrino-globulin, 
coagulating at 65° C. 

3. A nucleo-proteid. 


The nucleo-proteid of plasma.—Beyond the fact of its presence, and 
that it appears to be one of the essential factors in the formation of 
fibrin, very little is known regarding the nucleo-proteid of blood plasma. 
It is doubtful if it exists in the plasma of circulating blood; it is 
thought by many that in this it is confined to the white corpuscles and 
blood platelets—a very little being also present in the red corpuscles— 
and that it is shed out by these as soon as the blood is drawn. The 
reasons for this belief are— 

1. White blood corpuscles and similar cells (lymph cells, thymus 
cells, etc.) always contain a considerable amount of nucleo-proteid. 

2. In plasma obtained by subsidence of the corpuscles there is most 
nucleo-proteid in the lower layers, which contain most leucocytes; and 
least in the upper, which contain very few. 

3. Fluids which collect in the serous cavities of the body (peri- 
cardial fluid, hydrocele fluid, ascitic fluid) frequently contain no 
leucocytes. When this is the case they are also devoid of nucleo- 
proteid and of the property of spontaneous coagulability, although they 
contain fibrinogen. 

The nucleo-proteid is precipitated from oxalate plasma, by allowing 
it to stand for twenty-four hours at 0° C. The addition of acetic acid 
in slight excess also throws it down, but not in a pure form, for fibrin- 
ogen is carried down along with it. Its solutions are coagulated at 65° C. ; 
at a temperature of 60° C.,in presence of free alkali, it is split into 
nuclein anda proteid. This is stated by Pekelharing to be a proteose,? 
but its proteose character is denied by Martin.t Halliburton and Brodie 
could also find no proteose in blood after the injection of nucleo- 
albumin.® In the presence of soluble salts of lime, it forms a 


to justify this inference, and its presence is probably due to the fact that some or all of 
the nucleo-proteid present in the plasma is precipitated along with the fibrinogen, and 
clings to it in the subsequent processes of purification (Schiffer, Proc. Physiol. Soc., Journ. 
Physiol., Cambridge and London, 1895, p. xviii). See later, p. 172. 

1 Loc. cit. 

2 Schafer, Proc. Physiol. Soc., Journ. Physiol., Cambridge and London, 1895, vol. xvii. 
p. xx; Hammarsten, Zéschr. f. physiol. Chem., Strassburg, Bd. xxii. S. 384; Cramer, ibid., 
1897, Bd. xxiii. S.74. According to Hammarsten, this coagulum, like that produced in a solu- 
tion of the original fibrinogen, is not fibrin, but a fibrin-like combination of lime and fibrin- 
ogen. To me, however, it has often appeared difficult to distinguish from fibrin. 

’ Pekelharing, ‘‘ Untersuch. ti. d. Fibrin-Ferment,”” Amsterdam, 1892. 

+ Journ. Physiol., Cambridge and London, 1894, vol. xv. p. 375. 

5 Thid., 1894-5, vol. xvii. p. 159. 


= 


166 THE BLOOD, 


substance which possesses the property of converting fibrinogen into 
fibrin, and is, according to Pekelharing, a combination of the nucleo- 
proteid with lime, and identical with the fibrin ferment of A. Schmidt. 
The fibrin ferment is sometimes spoken of as “thrombin,’ and the 
nucleo-proteid material in the plasma from which it is produced is then 
termed “ prothrombin.” 

Wooldridge? found that, on subjecting peptone plasma to cold, he 
obtained a finely granular deposit, which had the property of producing 
clotting in fibrinogenous fluids, which are not themselves spontaneously 
coagulable, and of accelerating the process of clotting in coagulable fluids. 
To the material thus obtained, and which he described as having, under 
the microscope, an appearance similar to masses of blood platelets, he 
gave the name “ A-fibrinogen,” because he found that on adding it to 
peptone plasma it produced fibrin, and that the amount of coagulation 
was more or less proportional to the amount of A-fibrinogen added. It 
is not fibrinogen as the term is ordinarily used, but is probably either a 
nucleo-proteid, or a mixture of nucleo-proteid with globulin. A similar 
deposit occurs, as already stated, in oxalate plasma, on standing in the 
cold. A precipitate containing the same substance is also produced by 
adding magnesium sulphate solution in considerable amount to blood, and 
in both plasma and serum of certain animals on acidulation with acetic 
acid, but in both cases it is lable to be mixed with serum globulin. 
It also occasionally occurs in serum, on standing, even without the 
application of cold. Halliburton has suggested that the deposit in 
peptone plasma may be a part of the proteoses, which were injected into 
the blood, for he found that solutions of albumose were liable to give a 
similar deposit on cooling by means of ice, but there is not enough proteose 
present in peptone plasma to account for such deposit, and the fact that ib 
occurs under other conditions in plasma also negatives this supposition. 
These experiments of Wooldridge, and the behaviour of the body termed 
by him A-fibrinogen, will be again referred to in a subsequent section. 

Fibrin.Fibrin is the chief substance formed from fibrmogen in the 
coagulation of blood plasma, and it is also produced in the coagulation of 
lymph and other fibrinogen-containing fluids. It is usually got by whipping 
blood as it flows from the blood vessels with a bundle of wires or glass 
rods before it has had time to coagulate into a solid mass. The coagulum 
then forms upon the wires or rods, and can be washed free from adherent 
red corpuscles by putting it under a stream of water for a few hours. 
But to obtain pure fibrin it is necessary first to prepare fibrmogen from 
blood plasma by precipitation with NaCl (half-saturated), to purify this 
by re-solution and re-precipitation, and finally to cause the coagulation of 
the fibrinogen solution by fibrin ferment. The clot thus obtained, which 
must be thor oughly washed, is composed of nearly pure fibrin. 

When obtained by whipping blood, fibrin is a white stringy substance 
when wet, drying to a glue-like mass. The threads of which it is com- 
posed, and which, as may be seen in a microscopic preparation of blood, 
interlace with one another and form a network of the finest possible 
filaments, entangling the blood corpuscles in its meshes, have a strong 
tendency to retract or shorten when formed; this is the reason why a 
clot shrinks and expresses serum from its interior. Fibrin is slowly 
soluble in 5 to 10 per cent. solutions of certain salts, such as sodium 
chloride, sodium sulphate, potassium nitrate, magnesium sulphate, and 


1 Wright, Lancet, London, 1892, vol. i. pp. 457, 515. 


PROTEIDS OF PLASMA. 167 


ammonium sulphate, and also in iodides and fluorides, and in solutions 
of urea.t It is also very slowly dissolved to some extent by normal salt 
solution ; the solution is in all cases assisted by moderate warmth. Fibrin 
obtained from venous blood is slightly more soluble in salt solutions than 
that yielded by arterial blood. The proteid material which is found dis- 
solved after solution of fibrin in the above salts is composed of two 
globulins,” having heat coagulation temperatures of 55° and 75° respec- 
tively. The latter, according to Halliburton, is reduced to 60°-65° in 
sodium chloride solutions, being 73°-75° in magnesium sulphate solutions 
only. Albumoses are also present in the fluid (Limbourg, Dastre). This 
solution of fibrin in neutral salts occurs in the entire absence of putre- 
factive decomposition (Green, Dastre). Fibrin swells in dilute acid (such 
as 0°2 per cent. HCl) into a clear jelly, which very slowly undergoes 
solution with the formation of acid albumin and proteoses. Stronger acids 
and, with the aid of heat, weak acids, effect the conversion more readily. 
The addition of pepsin to the acids employed greatly accelerates the con- 
version, the fibrin first splitting into two globulins, one coagulating at 56° 
and the other at 75°,and then becoming transformed into acid-albumin, pro- 
teoses, and peptones.* Trypsin in alkaline solutions has a similar action.* 

Blood yields from -2 to ‘4 per cent. of its weight of dry fibrin. Ham- 
marsten° gives the following as the elementary composition of fibrin :— 


SO eS te 1-10 
ee. |i G83, |. Oud wees meee 
ae ea 


It is, however, never free from ash, and the ash invariably contains 
lime,® but not more than other proteids,’ nor does it contain more 
lime than the fibrimogen from which it is formed. Thus in one 
experiment Hammarsten found that a sample of fibrin, obtained by 
the action of ferment prepared from oxalated serum, upon fibrinogen 
prepared by precipitation from oxalated plasma by acetic acid, yielded 
exactly the same amount of lime as a sample of the fibrinogen itself, 
namely, 0-055 per cent. This fact completely disposes of the theories of 
coagulation which assume that fibrin is merely a combination of 
fibrinogen with lime, such as those of Freund, Arthus, Pekelharing, and 
Lilienfeld. Fibrin obtained by whipping blood leaves a considerable 
phosphorus-containing residue (nuclein) after subjection to peptic 
digestion ; this is probably largely derived from the nucleo-proteids of the 
entangled leucocytes. But even fibrin obtained from solution of purified 
fibrinogen in dilute salt solution yields a certain amount of such residue.® 
It is possible that this may be an accidental impurity, but, on the other 
hand, it may be an integral constituent of the fibrin. 


1 Dastre, Arch. de physiol. norm. et path., Paris, 1895, p. 408; Compt. rend. Acad. d. 
sc., Paris, 1895, tome cxx. p. 589. See also on the solubility of fibrin in neutral salts, 
Holzmann, Arch. f. Physiol., Leipzig, 1884, S. 210; and Arthus, ‘‘Coag. des liquides 
organiques,” Paris, 1894, pp. 105 e¢ seq. 

2 Green, Journ. Physiol., Cambridge and London, 1887, vol. viii. p. 372. 

° Hasebrock, Ztschr. f. physiol. Chem., Strassburg, Bd. xi. S. 348. 

4A. Herrmann, ibid., Bd. xi. S. 508. The other literature on this subject will be 
found in Halliburton, ‘‘ Text-Book of Physiol. and Path. Chemistry.” 

5 Arch. f. d. ges. Physiol., Bonn, Bd. xxii. 8. 484. 

© Frederikse, Ztschr. f. physiol. Chem., Strassburg, 1894, Bd. xix. S. 143. 

7 Hammarsten, ibid., Bd. xxii. S. 392. ; 

8 Schafer, Proc. Physiol. Soc., Journ. Physiol., Cambridge and London, 1895, vol. 
Xvii. p. Xx. 


168 THE BLOOD. 


THEORIES OF COAGULATION. 


That the coagulation of the blood is due to the formation of an 
insoluble substance (fibrin) in the plasma, was proved by Hewson,! who 
showed that a coagulable plasma can be obtained by skimming, after 
allowing the corpuscles to subside, in blood the coagulation of which 
1s delayed in any way, as by cold, by neutral salts, or by its retention 
within a living vein. The old theories which ascribed the coagulation to 
the cooling of “the blood, to its coming to rest, to the running together 
of the corpuscles into youleaux, were all effectually disproved by the 
same careful observer. Hewson also showed that fibrinogen (“ coagul- 
able lymph”) is precipitable and removable from plasma by a tempera- 
ture of a little over 50° C.2. Many of Hewson’s observations upon 
coagulation were forgotten, and the facts rediscovered by subsequent 
observers, but their accuracy was such that until comparatively modern 
times no addition of any permanent value to the knowledge of the 
subject was made. The most important of such additions (which was 
also overlooked for many years)? was the observation of Andrew 
Buchanan, that a substance could be extracted by water and solutions of 
salt from lymphatic glands, from blood clot (especially the buffy coat), 
and from various tissues, which had the property of producing the 
coagulation of serous fluids, not themselves spontaneously coagulable, 
such as hydrocele and pericardial fluid; such action being comparable 
to that of a ferment. But it is only quite recently that the active sub- 
stance extracted by Buchanan has been examined, and found to belong 
to the class of bodies known as nucleo-proteids. 

Schmidt's theory.—A theory of coagulation, which was long accepted, 
was that of Alexander Schmidt. Schmidt noticed that fluids which 
contained fibrinogen but were not spontaneously coagulable, such 
as pericardial or hydrocele fluid, coagulated on the addition of serum. 
He ascribed the fibrin formation which resulted to the action (fibrino- 
plastic action) of the globulin in the serum upon the fibrinogen of the 
pericardial fluid. Since, however, the same globulin is already present 
in abundance in pericardial and hydrocele fluid, it became clear that 
this explanation of the action of serum was insufficient. It was, how- 
ever, shown by Schmidt that a substance is extracted by water from the 
alcohol precipitate of blood or serum, which possesses the property of 
causing coagulation in these fibrinogenous liquids, or of causing coagula- 
tion in plasma, the coagulation of which has been prevented by the 
addition of neutral salts. To this substance the name of fibrin ferment 
was applied, on account of its action resembling in general that of the 
unorganised ferments or enzymes. Thus it was found to have its 
activity accelerated by warmth, and destroyed by a high tempera- 
ture (65° C.), and also to be capable of producing the coagulation of a 
relatively large amount of fibrinogen. It was still held by ‘Schmidt that 
the globulin of serum takes an important share in the formation of fibrin. 

Hammarsten’s earlier researches—Hammarsten showed that serum 


OneCtt. 

* For the history of this see Schiifer, Journ. Physiol., Cambridge and London, 1880, 
vol. ili. p. 185. 

* Of. Gamgee, ‘‘ Physiol. Chemistry,” 1880, vol. i., where will also be found an excellent 
account of the earlier history of the subject of blood coagulation. See also Arthus, ‘‘ Coag. 
des liquides organiques,” Paris, 1894, for a good epitome of the history of the subject up 
to that date. 


THEORIES OF COAGULATION. 169 


globulin does not take part in forming fibrin. By precipitating fibrin- 
ogen by half-saturating plasma with sodium chloride, he obtained it 
free from serum globulin, and found that its solution in dilute salt 
solution was coagulated by the addition of Schmidt’s extract—the so- 
ealled fibrin ferment—alone. Hammarsten proved that coagulation 
consists in a conversion of fibrinogen into fibrin; the change being 
accompanied by a splitting of the fibrinogen, and not by a combination 
of it with the serum globulin, as was supposed by Schmidt. 

Influence of lime salts— Theories of Freund and of Arthus and Pages. 
—The more recent researches since these of Hammarsten have been 
in the direction of elucidating the true nature of the substances 
contained in Schmidt’s extract. Green! found the extract to contain 
sulphate of lime, and that if lime were removed from plasma by 
dialysis its coagulability became lost, but was restored by the addition 
of sulphate of lime. Ringer and Sainsbury? showed that other salts of 
lime, such as calcium chloride, might replace the sulphate, and that the 
calcium might be replaced by barium and by strontium, although the 
salts of these metals are not so efficacious as the corresponding salts 
of calcium. 

Freund ° also drew special attention to the important part played by 
lime salts in promoting the formation of fibrm. He supposed the 
original cause of the deposition of fibrin in fibrinogenous liquids to be 
the formation of insoluble tribasic phosphate of lime, by the interaction 
of soluble phosphates (which he supposed to be shed out from the 
corpuscles whenever they come in contact with and adhere to foreign 
surfaces) with soluble lime salts contained in the plasma; the lime 
phosphate combining at the moment of formation with fibrmogen, and 
forming fibrin, and no other agency in the shape of a special ferment 
being necessary. This inference has not, however, been confirmed by 
subsequent observers. Freund supposed neutral salts, peptone, etc., to 
act in preventing coagulation, by keeping phosphate of lime in solution, 
and the walls of the blood vessels to act in preventing coagulation 
because the corpuscles do not adhere to them. Freund based his theory, 
partly upon the fact that if blood is drawn from an artery through a 
tube smeared with oil or vaseline into a vessel similarly prepared, the 
blood remains fluid for a long time, presumably because the adhesion of 
the corpuscles to the walls does not occur. Similar experiments with 
blood kept surrounded by paraffin or oil were performed by Haycraft 
with like result.4 

Arthus and Pages® mixed blood as it flowed from the vessels with a 
small quantity of a soluble oxalate ® (0:‘07-0-1 parts per 100 of blood) 
sufficient to precipitate the lime salts dissolved in the plasma. They 
found that blood thus treated did not coagulate, however long it might 
be kept,’ but that coagulability of its plasma is immediately restored on 
again adding a soluble lime salt, such as calcium chloride. They 

1 Journ. Physiol., Cambridge and London, 1887, vol. viii. p. 354. 

2 Thid., 1890, vol. xi. p. 369. 3 Med. Jahrb., Wein, 1888, S. 259. 

4 Journ. Anat. and Physiol., London, 1888, p. 172 ; Hayeraft and Carlier, ibid., p. 582. 

5 Arch. de physiol. norm. et path., Paris, 1890, p. 739; Arthus, Thése de Paris, 1892. 

§ Solutions of soap (0°5 parts per 100 of blood) or of soluble fluorides (0°2 parts per 100 
of blood) act similarly to those of oxalate. 

7 Hammarsten makes a similar statement for horse’s blood, but it is certainly not 
correct for all kinds of blood. Oxalate plasma, obtained from dog’s or sheep’s blood, does 


undergo coagulation on standing; coagulability is therefore not abolished by precipita- 
tion of the lime by oxalate, but merely deferred. We shall return to this point immediately. 


7° THE BLOOD 


inferred that the presence of a soluble salt of lime is necessary to the . 
formation of fibrin, which, according to them, is produced by a combina- 
tion, under the influence of fibrin ferment, of a part of the fibrinogen 
with lime, the remainder of the fibrinogen—which is assumed to split 


into two parts—forming a globulin coagulating at 64° C. (Hammarsten’s 
fibrino-globulin).2 


. Whilst it would appear from these researches that soluble lime salts are 
necessary to the formation of fibrin,? it has been shown by Horne that the 
presence of a slight excess of these salts and also those of barium and strontium 
will hinder or, in great amount, entirely prevent its formation; their action 
being far more marked in this respect than that of other neutral salts, which 
require to be mixed in much greater amount with blood to prevent its co- 
agulation.? The reason for this is probably to be found in the fact that fibrin 
is soluble to some extent in neutral salts of a certain strength (including salts 
of calcium, barium, and strontium). 


Influence of nucleo-proteid.— Theory of Pekelharing—Halliburton * and 
Pekelharing ® both obtained from Schmidt’s extract a body giving proteid 
reactions, and resembling in many particulars the globulins, to which 
class of proteids they at first regarded it as belonging.® They showed 
that the ferment action of Schmidt’s extract is intimately dependent 
upon the presence of this substance, which could also, as Halliburton 
showed, be obtained from lymphatic glands. Halliburton termed it 
cell globulin; subsequently both observers recognised the fact that the 
substance in question was not a true globulin but a nucleo-proteid.7 
According to Pekelharing, it possesses the property of combining with 
lime, which it does not yield to distilled water by dialysis, nor is the 
combination broken up by soluble oxalates, although these, if present 
from the first, may prevent the original combination. The albumose in 
commercial peptone also prevents such combination, the albumose itself 
combining with the lime salts present ;§ if these are in excess, “ peptone ” 
does not prevent coagulation from taking place. The lime combination 
of nucleo-proteid is, according to Pekelharing, the body which has been 
known as fibrin ferment (thrombin). It can be formed not only from 
the nucleo-proteids contained in plasma or serum, but also from nucleo- 
proteids in the cells of the thymus, testicle, and other glands, by 


* Arthus and Pagés found that strontium can replace lime in this reaction, but that 
barium and magnesium cannot. Ringer and Sainsbury have, however, shown that barium 
may take the place of lime in promoting coagulation, although it is less powerful (Journ. 
Physiol., Cambridge and London, 1890, vol. xi. p. 369). They also found that the salts*of 
sodium and potassium act antagonistically to those of lime, barium, and strontium. 4 

* A. Schmidt, even in his last communication upon the subject (‘‘ Weitere Beitr. z. 
Blutlehre,” Wiesbaden, 1895), denied altogether that lime salts have any specific action 
or differed from other neutral salts, aud considered that the addition of a soluble oxalate to 
blood acts either by preventing the formation of fibrin ferment or by hindering the action 
of ferment, if present, on fibrinogen. Cf., however, Arthus, Arch. de physiol. norm. ct 
path., Paris, 1896, and Hammarsten, Zoe. cit. 

* Journ. Physiol., Cambridge and London, 1896, vol. xix. p. 356. Wright also noticed 
the fact that considerable excess of calcium added to oxalate blood prevents coagulation, 
Journ. Path. and Bacteriol., Edin. and London, 1893, vol. i. p. 434. 

4 Proc. Roy. Soc. London, 1888, vol. xliv. p. 255. 

> Festschr. Rudolf Virchow, Berlin, 1891, S. 435. 

° Lilienfeld has recently repeated this error, Ztschr. f. physiol. Chem., Strassburg, 
1BYols Sox 

 Pekelharing, ‘‘Untersuch. ii. d. Fibrin-ferment,” Amsterdam, 1892; Halliburton, 
Journ. Physiol., Cambridge and London, 1895, vol. xviii. p. 312. 

8 Pekelharing. Cf., however, C. J. Martin, ‘‘Venom of Australian Black Snake,” 
pp. 36-40, Journ. and Proc. Roy. Soc. New South Wales, Sydney, July 3, 1895. 


=e 


ee 


oe” 


THEORIES OF COAGULATION. ws 


digesting these with calcium chloride, the excess of calcium salt being 
afterwards dialysed off. Pekelharing supposes that the ferment action 
consists in the transference of lime from its nucleo-proteid combination 
to fibrinogen, the lime-compound of this being the insoluble fibrin,’ and 
that if there is more lime salt in the solution the nucleo-proteid can 
recombine with lime, and thus become reconstituted as an agent for the 
conversion of fibrinogen into fibrin. As already pointed out (p. 166), 
however, it is not possible to accept this theory in view of the analyses 
of fibrin and fibrinogen given by Hammarsten. Pekelharing has himself 
shown that even: in the entire absence of free lime salts, or in the 
presence of soluble oxalates, the transformation of fibrinogen into fibrin 
may be produced, provided that the ferment is present.? This has also 
been shown to be the case by A. Schmidt? and by myself, and more 
recently in a series of carefully conducted experiments by Hammarsten. 
Hammarsten precipitated fibrinogen by oxalated solution of salt, and, 
after purifying it by repeated re-solution and re-precipitation, added to 
its solution a fibrin ferment obtained from oxalated serum, and obtained 
as the result a typical fibrin.® 


Exception has been taken to the inference drawn by Pekelharing that 
Schmidt’s ferment is a compound of nucleo-proteid and lime, on the ground 
that the ferment contained in Schmidt’s extract differs from nucleo-proteids 
in the effect of alcohol upon its solubility in water, and in the fact that 
nucleo-proteids cause coagulation in intravascular plasma, which Schmidt’s 
extract does not, whereas the latter causes coagulation in extravascular (salted) 
plasma, and nucleo-proteids do not.6 The differences may, however, depend, 
in part at least, upon the relative amounts of nucleo-proteid and lime. Thus 
in Schmidt’s extract the amount of nucleo-proteid is small and the amount of 
lime large ; in extracts of thymus and the like the amount of nucleo-proteid 
is large and the amount of lime small. In part also they depend upon other 
circumstances, such as the influence of the magnesium sulphate of the salted 
plasma in antagonising the effect of lime.’ 

The origin of the nucleo-proteid of plasma and serum is probably the white 
corpuscles. It would appear that many of the latter disintegrate after removal 
of blood from the body. Giirber® found that in coagulated blood the number 
of white corpuscles was reduced to one-half, the difference being chiefly in the 
number of polynuclear cells. This disappearance has not, however, been 
found by all observers, and is not fully admitted. Nevertheless, without 
actually disintegrating, the white corpuscles may shed out or secrete nucleo- 
proteid into the plasma. This may occur normally in mere traces, but on with- 


1 Centralbl. f. Physiol., Leipzig u. Wien, 1895, No. 3. 

2 It would appear that a soluble oxalate does not throw down all the lime from a proteid- 
containing fluid, and that a trace of lime is still held in solution so that an oxalate plasma 
is not lime-free, as was supposed by Arthus and Pages. This is well illustrated by an 
observation by Ringer upon the frog’s heart, who finds that a normal saline solution, 
to which a little CaCl, has been added, will exhibit the physiological effect of lime, 
even after the addition to the fluid of a slight excess of a soluble oxalate. It may be 
inferred from this that a trace of lime may be held in solution even in a fluid destitute of 
proteid. 

3 “* Weitere Beitr. z. Blutlehre,’” Wiesbaden, 1895. 

4 Proc. Physiol. Soc., Journ. Physiol., Cambridge and London, 1895, vol. xvii. 
p. xviii. 

® Ztschr. f. physiol. Chem., Strassburg, Bd. xxii. 

§ Halliburton and Brodie, Journ. Physiol., Cambridge and London, 1894, vol. xvii. p. 143. 

7 Pekelharing, Centralbl. f. Physiol., Leipzig u. Wien, 1895, Bd. ix. S. 102. Halliburton 
in a recent paper (Journ. Physiol., Cambridge and London, 1895, vol, xviii.) comes to a 
similar conclusion, namely, that Schmidt’s fibrin ferment is a weak solution of nucleo- 
proteid. It produces Wooldridge’s negative phase when intravenously injected. 

8 Sitzungsb. d. phys.-med. Gresellsch. zu Wiirzburg, 1892, No. 6. 


172 THE BLOOD. 


drawal from the body in larger amount. It is noteworthy in this connection 
that certain forms of lymph, such as the aqueous humour, which contain no 
cells, contain also no nucleo-proteid, and are only coagulable on the addition of 
nucleo-proteid. 


Theory of Lilienfeld.—Lilienfeld; like Arthus and Pekelharing, con- 
siders that fibrin is formed by a combination of fibrinogen with lime, any 
soluble lime salt being equally effectual to produce the combination. 
Lilienfeld differs, however, from them in denying the necessity for the 
intervention of a ferment in the ordinary sense of the word. He considers 
that what the nucleo-proteid effects is not the combination of fibrmogen 
with lime, but a transformation or splitting of the fibrmogen into a sub- 
stance which he terms “ thrombosin,” and a globulin ; the thrombosin then 
combines with lime, if any be present, to form fibrin. The nucleo-proteid 
only acts, according to Lilienfeld, by reason of the acid qualities of the 
nucleic acid it contains. Any other weak acid, e.g. acetic, will answer 
equally well. Thus, if a solution of fibrmogen in NaCl (prepared 
according to Hammarsten’s method) is precipitated by acetic acid, the 
precipitate (thrombosin), if dissolved in weak sodium carbonate, instantly 
forms a coagulum (fibrin), on the addition of calcium chloride. The 
formation of the thrombosin by the action of an acid upon fibrinogen 
is, according to Lilienfeld, a precursor to the production of fibrin, and 
is analogous to the change in caseinogen by the action of rennin, which 
will occur in the absence of lime salts, although the latter are necessary 
for the formation of the casein clot (see p. 135). 

I have elsewhere shown ? that this theory is untenable; for a solution 
of fibrinogen in dilute salt solution, prepared by Hammarsten’s method, 
will, if sufficiently strong, coagulate, on the addition of calcium chloride, 
equally well with a solution of the acetic acid precipitate—the so-called 
thrombosin—although somewhat less rapidly.* The difference in rapidity 
depends, no doubt, upon the fact that sodium chloride in a certain 
amount retards the formation of the clot, or even may prevent it 
altogether. This, as Hammarsten has pointed out, is the reason why 
Lilienfeld obtained no coagulum on the addition of calcium chloride 
to his fibrinogen solution, although he got a coagulum with his 
so-called thrombosin solution, for the former was dissolved by aid 
of sodium chloride, and the latter by dilute alkali As already 
stated,t Hammarsten holds that in neither case is the coagulum pro- 
duced a true fibrin, but in both eases it is a fibrin-like combination 
of fibriogen with lime. The influence of nucleo-proteid is, however, 
not eliminated? for, as has been already insisted on, fibrinogen pre- 
pared by Hammarsten’s method always contains some nucleo-proteid. 
This is clear both from my own experiments and from the analyses 
of Lilenfeld, who indeed—but as it would appear without sufficient 
cause—supposes fibrinogen itself to be a nucleo-proteid. The amount 
of nuclein or phosphorus which can be obtained from it certainly does 
not warrant the assumption; nevertheless there is always a distinct 


1 Zischr. f. physiol. Chem., Strassburg, 1895, Bd. xx. 

2 Proc. Physiol. Soc., Jour nm. Ph ysiol., Cambridge and London, 1895, vol. xvii. 
p- Xvili. 

3 Cf. Cramer, Ztschr. f. physiol. Chem., Strassburg, 1897, Bd. xxiii. S. 74, who has 
fully confirmed the conclusion that the so-called “thrombosin ” is merely fibrinogen. 

4 See note 5, p. 165. 

® Cf. Wistinghausen, Diss., Dorpat, 1894. 


> 


THEORIES OF COAGULATION. E73 


residue after gastric digestion of its solution, showing that it at least, 
as above stated, contains some nucleo-proteid. Probably this is an 
accidental contamination. 

Production of intravascular coagulation of blood and of uncoagulable 
blood.—It was discovered by Edelberg! that intravenous injection of 
Schmidt's fibrin ferment may produce thrombosis in the venz cave, 
the right side of the heart, and the pulmonary arteries. Foa and 
Pellacani? showed that the same will occur with extracts of various 
organs. The same fact was independently noticed by Wooldridge? 
who found that a substance or substances obtainable from saline extract 
of lymphatic glands, thymus, testicle, and other glandular organs, tend to 
produce, when injected rapidly in sufficient amount into the veins of 
animals, instant coagulation of the blood whilst still within the blood 
vessels. On the other hand, if injected more slowly, or in insufficient 
amount to produce intravascular coagulation, the coagulability of the 
blood in vitro becomes abolished; this condition was termed by Wool- 
dridge the “ negative phase.” When the negative phase is once obtained, 
a very large dose of the material fails to produce intravascular clotting. 
Wooldridge gave the name “ tissue fibrinogens” to the substances thus 
extracted, and more extended knowledge has led to the general recog- 
nition of the fact that they belong to the class of nucleo-albumins or 
nucleo-proteids. The coagulation when it occurs is found, first, in the 
portal venous system ; then in the general venous system, and pulmonary 
arteries and in the right side of the heart; and finally, when the effect 
is most pronounced, in the general arterial system; but rarely in the 
pulmonary veins. Its occurrence is assisted by an excess of CO, in the 
blood.® Albino rabbits and the Norway hare in its albino condition are 
immune to these effects (Pickering). 

It has been supposed by Lilienfeld ® that this action of the nucleo- 
proteid in causing coagulation is due to the nuclein or nucleic acid 
which it contains, and that, when the negative phase is obtained, this 
result is due to the action of the proteid part of the molecule of 
nucleo-proteid in preventing coagulation. ‘This hypothesis is rendered 
improbable by the observations of Halliburton and Pickering,’ who 
found that intravascular coagulation can be readily obtained in rabbits 
by intravenous injection of artificial colloids (containing no nucleic 
acid).8 These colloids likewise yield the negative phase (retardation of 
coagulation), if injected in quantity insufficient to produce coagulation ; 
and, as with solution of nucleo-proteids, they are without action upon 
albino rabbits. | Nevertheless, like solutions of nucleo-proteid, they 
hasten the coagulation of the blood of other animals, if mixed with it 
im vitro. These observers also found that the retarding influence of 

1 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1880, Bd. xii. S. 283. 

2 Riv. clin. di. Bologna, 1880, p. 241. 

® Proc. Roy. Soc. London, 1886. See also ‘‘Die Gerinnung des Blutes,” Leipzig, 1891. 

4 Wooldridge, Arch. f. Physiol., Leipzig, 1888. 

5 Wright, Journ. Physiol., Cambridge and London, vol. xii. 6 Loc cit. 

7 Jowrn. Physiol., Cambridge and London, 1895, vol. xviii. pp. 54 and 285 ; Pickering, 
Proc. Roy. Soc. London, 1896, vol. 1x. p. 337. 

8 The artificial colloids investigated were prepared by Grimaux’s methods (Compt. rend. 
Soc. de biol., Paris, 1881, tome xcili. p. 771; 1884, xeviii. pp. 105, 1434, and 1578). 
Their chemical properties and mode of preparation have already been described by Professor 
Halliburton in a previous article (p. 36). It is possible that they may act, not directly, 
but by setting free nucleo-proteid from the white corpuscles. Their solutions do not, 


however, cause disintegration either of the red or white corpuscles, nor any apparent 
change in the epithelium of the vessels. 


174 THE ELOOD: 


intravascular injections of soap, peptone, and potassium oxalate on the 
coagulation of blood is antagonised by previous intravascular injection of 
the colloid. The action of the colloids in promoting coagulation is 
assisted, like that of nucleo-proteid, by accumulation of CO, in the 
blood. The same effects are produced by snake venom,! which contains 
no nucleo-proteid, and the active principles of which consist of albumoses. 
This produces, although in far more minute doses, effects which are in 
every way comparable with those produced by Wooldridge’s “tissue 
fibrinogen.” In doses of 000001 to 0:00002 grm. per kilog. body weight, 
the venom of the Australian black snake (Pseudechis porphyriaca) causes 
the blood, after a brief interval of increased coagulability (positive 
phase), to lose its tendency to clot (negative phase), and much larger 
doses of the poison will now not restore its coagulability. On the other 
hand, moderate and large doses (more than 0:0001 grm. per kilog.) 
produce instantaneous clotting within the vessels. But any blood 
which has not undergone the intravascular coagulation is found to be 
incoagulable in vitro, and in this point also there is an exact resemblance 
to the phenomena produced by nucleo-proteids and by artificial colloids. 

Solutions of certain other chemical substances, such as ether, tannic 
acid, arsenic,” glycerin, toluylenediamin,? are also found when injected 
into the circulation to produce thrombosis. But, to produce the effect, 
these all require doses large enough to cause disintegration of the 
blood corpuscles, thereby setting free the nucleo-proteids which the 
corpuscles contain, so that their action is probably a secondary one. It 
is possible that snake venom may also operate in this way,* since it does 
produce to a certain extent such disintegration, but the rapidity of the 
production of the intravascular clotting, and the small amount of such 
disintegration which normally occurs, render such an_ explanation 
unprobable. 

Peptone plasma.—Researches of Wooldridge.-—Other substances, such 
as commercial peptone, the action of which is due to the albumoses which 
it contains, and leech extract, produce a diminution or loss of coagulability 
when injected into the blood vessels, without, in any dose, tending to cause 
intravascular coagulation. The incoagulable blood or plasma obtained 
by their employment resembles very closely that obtained in the negative 
phase, produced by Wooldridge’s tissue fibrmogen, by colloids and by 
snake venom. Peptone plasma can be made to coagulate by 


Addition of lymph cells. 

Addition of nucleo-proteids. 

Addition of calcium chloride. 

Dilution with water, or 0°5 per cent. salt solution. 
A stream of CO,. 

Neutralisation with acetic acid. 


ou 29 bo 


But if an excess of the reagents employed to prevent coagulation 
(or to produce the negative phase), whether peptones or slowly 


1C. J. Martin, Journ. Physiol., Cambridge and London, 1893, vol. xv. p. 380; and 
Journ. and Proc. Roy. Soc. New South Wales, Sydney, July 3, 1895. These papers contain 
full references to the previous literature of the subject. 

2 The administration of arsenic and phosphorus by the mouth diminishes the coagulability 
of the blood (cf. Gley and Pachon, Arch. de physiol. norm. et path., Paris, 1896, p. 716). 

3 Silbermann, Virchow’s Archiv, 1889, Bd. exyii. S. 288. 

40. J. Martin, op. cit., Journ. and Proc. Roy. Soc. New South Wales, Sydney, pp. 45-47 
of reprint. 


THEORIES OF COAGULATION. 175 


administered nucleo-proteids or snake venom be employed, then these 
additions do not produce coagulationt In view of the fact that 
calcium chloride will not, under these circumstances, produce coagula- 
tion, the hypothesis of Freund and Pekelharing, that “peptones” 
deprive blood of its coagulability by combining with its calcium salts, 
loses probability. 


Peptone injected intravenously rapidly disappears from the blood.2 The 
action of peptone differs from that of leech extract, in that a second dose, 
given soon after the action of the first dose has passed off, fails to produce an 
effect on coagulability. Moreover, the blood of a “peptonised” dog confers 
immunity from the action of peptone, if injected intravenously into a second 
animal.® 


The properties of peptone plasma, and the effects of leucocytes and 
their saline extracts upon the coagulability of blood, were carefully 
studied by Wooldridge. This observer found, as already stated, that if 
peptone plasma be kept for a time at 0° a precipitate forms, which takes 
the form, under the microscope, of minute discoid particles, almost exactly 
similar to blood platelets. The substance thus precipitated was termed 
“ A-fibrinogen” by Wooldridge, while he named the substance precipit- 
able by half-saturation with NaCl “B-fibrinogen”; this is the same 
thing as fibrinogen as ordinarily understood. After the removal of the 
A-fibrinogen, the coagulability of peptone plasma by CO, and other 
conditions is greatly diminished or altogether lost, but is restored on 
dissolving the A-fibrinogen again with the aid of warmth. 


Wooldridge’s A-fibrinogen is also obtainable, as Wright has shown, by 
cooling oxalate plasma, and it is probably composed mainly, if not entirely, 
of nucleo-proteid. It has been shown by Hammarsten that if by prolonged 
cooling and filtration it is removed as much as possible from oxalated plasma, 
the plasma will not coagulate on the addition of sufficient lime salts to more 
than balance the excess of oxalic acid, but that, if the precipitate be collected 
and treated with lime salts, it furnishes, on subsequently removing the 
lime by oxalate, a powerful thrombin or fibrin ferment. Hammarsten 
accordingly terms the substance in question, which is precipitated by cold 
from plasma, prothrombin, and considers that it can only be converted into 
thrombin by the action upon it of lime salts. Pekelharing regards the 
precipitate in question as composed of nucleo-proteid, and considers that the 
lime acts by combining with it to form fibrin ferment. 


The addition of lymph cells (washed with 0°6 per cent. NaCl solution) 
to peptone plasma causes its coagulation outside the body, and also acceler- 
ates the coagulation of ordinary blood in vitro, whereas the intravenous 
injection of salt solution holding these washed lymph cells in suspension 
produces an incoagulable condition (negative phase) of blood, which 
does not then coagulate, even on withdrawal. But on addition of some 
of this fluid, holding cells in suspension, to such blood after withdrawal, 
coagulation is rapidly produced. The loss of coagulability of peptone 
plasma is not due, as was supposed by A. Schmidt, to the disappearance 
and disintegration of leucocytes, for, as Wooldridge showed, the addition 


1¢. J. Martin, op. cit., pp. 35-40. According to Dastre and Floresco, the chief cause of 
the lack of coagulation in peptone plasma is its high alkalinity (Arch. de physiol. norm. et 
path., Paris, 1897, p. 216). 

2 Schmidt-Mulheim, Joc. cit. 

° Contejean, Arch. de physiol. norm. et path., Paris, 1895. 


176 THE BLOOD. 


of leucocytes to the circulating blood does not increase its coagulability, 
but the COMIaEy and, moreover, peptone plasma contains man 

leucocytes! These several facts were explained by Wooldridge by 
the supposition that coagulation is produced or prevented in the 
absence of leucocytes by the action of one substance in the plasma upon 
another, or in the presence of leucocytes by the action of a substance 
within the plasma upon these cells, or material yielded by them; the 
kind of interaction being different under different circumstances, and 
producing, respectively, “the phase of incoagulability or coagulation 
(negative or positive phase) according to such circumstances. All such 
substances, which by their interaction tended to produce fibrin, were 
termed by Wooldridge “ fibrinmogens”; but the progress of research has 
since rendered it probable that Wooldridge’s “ A-fibriogen” obtained 
from plasma, his “serum fibrinogen ” obtained from dog's serum, and 
the “tissue fibrinogens,” which he obtained from various organs, all 
owe their action to the nucleo-proteid which they contain. Translating, 
then, the phraseology employed by Wooldridge, the alterations in 
blood plasma, which come under the various conditions above noticed, are 
due to the interaction of nucleo-proteids and fibrmogen. And it would 
appear that, when in the interaction the nucleo-proteids are present in 
relatively small amount, the negative phase is the result; when in 
large amount, the positive phase. Also that, when added to the 
circulating blood, leucocytes yield but little of their nucleo-proteid to 
plasma, and hence a negative phase is the result; but, on the other 
hand, when added to plasma in vitro, a larger amount is yielded, and 
coagulation results. A remarkable observation, and one very difficult to 
explain, is the fact that, if the negative phase is once established by the 
intravascular injection of a small amount of nucleo- -proteid, artificial 
colloid, or snake venom, a large excess of the same will then not only 
fail to produce the positive phase, but will even strengthen the negative 
phase. It is, therefore, only the initial change which is influenced by 
the relative amounts of interacting material; and, when once this change 
is established, it does not again become modified. 

Wright's experiments. —Wooldridge further found that under some cir- 
cumstances the amount of fibrin pr oduced was dependent upon the amount 
of tissue fibrinogen or A-fibrinogen (nucleo- proteid) added to plasma. He 
therefore came to the conclusion, since the extent of action was not in all 
cases independent of the amount of these substances, that the action could 
not be looked upon as that of a ferment, although under some cir- 
cumstances the extent of action did appear to be independent of the 
amount of these substances. Wooldridge offered no explanation of the 
different effects obtained with large and small doses respectively, his 
work upon the subject having been cut short by his untimely death. 
It has, however, been continued on the same lines by Wright,? who, 
whilst confirming most of Wooldridge’s observations, has added 
materially to our knowledge of the conditions under which “ tissue 
fibrinogen” or nucleo-proteids produce the negative and positive phase 
of coagulability. Wright states that the extracts of glands containing 


1 Wright found, however, that the number of leucocytes in peptone blood was extremely 
reduced, much more so than is the case in oxalate or magnesium-sulphate blood, and that 
it contains a correspondingly larger amount of nucleo- albumins, Proc. Roy. Soe. London, 
10th Feb. 1898. 

2 Proc. Roy. Irish Acad., Dublin, 1891, 3rd series, vol. ii. p. 117. 


THEORIES OF COAGULATION. ts 


these substances readily yield, under the influence of certain reagents 
and conditions, a body or bodies giving albumose reactions; and he Peas 
that such a body is also present in the blood after their injection, and 
rapidly appears in the urine.1 Wright considers it probable, therefore, 
that the contrary effects of large and rapid, or small and gradual, 
administration of these extracts is due in the one case to the immediate 
action of the nucleo-proteids in effecting the conversion of the fibrinogen 
into fibrin before there has been time for the formation of albumose; 
and in the other case, where there has been time for such formation, to 
the action of the albumose thus formed in preventing coagulation (as 
in the case of directly injecting albumose into the blood vessels). If 
any albumose is formed, the action of this would, by delaying coagula- 
tion, give time for the formation of more, when a second dose of 
nucleo-proteids is injected. Hence, a dose of nucleo-proteid, which would, 
if administered rapidly, produce instantaneous coagulation throughout 
the vascular system, may, if administered oradually, tend altogether to 
prevent coagulation. But, as Halliburton points out, the explanation of 
the action of “peptone” in producing a negative form of coagulation 
may be that it liberates small quantities of nucleo- -proteid, rather than 
that it removes calcium: and if this is so, the explanation offered by 
Wright (and Pekelharing) of the action of nucleo-proteids falls to the 
ground. Moreover, it cannot be accepted as proven that a “peptone” 
moiety is split off from nucleo-proteid. “ Peptone” (7.e. “albumose”)- 
blood is characterised by extreme diminution of the amount of CO, 
which it contains, and by diminished alkalinity,®? and the reason for 
the uncoagulability of such blood is apparently connected with its 
deficiency in CO, ‘tension, since it coagulates on passing a stream of 
CO, throughout it. For the occurrence of intravascular coagulation, 
alter injection of nucleo-proteid and similarly acting substances, is 
largely influenced by the amount of CO, in the blood, ‘and it is due to 
its richness in CO, that the blood coagulates under these circumstances, 
first in the systematic veins, and of these most readily in the portal 
venous system.° 

From what has been before said as to the influence of lime, it will be 
understood that the lime-salts of the plasma play an essential part in the 
interaction between the nucleo-proteid and the fibrinogen. This parti- 
cipation of lime in the reaction had not yet been ‘recognised when 
Wooldridge’s researches were made, but is freely admitted by Wright, 
whose views upon the subject of the combined action of nucleo- proteid 
and lime in producing coagulation seem to be in close agreement with 
those of Pekelharing (see p- 171). It is, however, still by no means 
clear why in “peptone” plasma, where all the necessary factors for the 
formation of fibrin are present, coagulation, nevertheless, does not occur, 


1 This has been also shown independently by Pekelharing (‘‘ Untersuch. u. d. Fibrin- 

ferment,” Amsterdam, 1892), who offers a similar explanation of the phenomenon of 
negative and positive coagulation. Halliburton and Pickering, on the other hand, con- 

sider that, in the case of colloids, the negative phase cannot be regarded as a subsidiary 
phenomenon, due to disintegration of the material intravenously injected, but is rather a 
result characteristic of the action of small doses, and is comparable to the inhibitory action 
of small doses of certain drugs, which act contrary to the action of larger doses (such as the 
physiological immunity produced by small doses of ene) 

? Lahousse, Arch. f. Physiol., Leipzig, 1889, S. 

8 Salvioli, Arch. ital. de biol., Turin, 1892, vol. at. PwlSD: 

4 Wright, Joc. cit., and Journ. Path. and Bacteriol., Edin. and London, 1893, vol. i. p. 434. 

®* Wright, Journ. Physiol., Cambridge and London, 1891, vol. xii. 


VOL ls —— 5 2 


2 


178 THE BLOOD. 


although it speedily occurs on further addition of lime or on passing 
CO,. "W. right ! assumes that the nucleo-proteid acting as a weak acid 
has ousted CO, from the bases of the plasma, and that the action of CO, 
is to set the nucleo-proteid free again. But this would not account for 
the effect of addition of calcium chloride. It may, on the other hand, be 
that the lime which is present in the plasma is unable to act upon the 
nucleo-proteid also present, owing to the former having entered into some 
combination from which it is set free by CO,. It must be admitted 
that the subject is still, in spite of much research, enveloped largely in 
obscurity. 


Influence of the liver and lungs upon blood coagulability.—It was shown by 
Pawlow? that if blood be allowed to circulate through the heart and lungs 
only, and be cut off from the rest of the body, it gradually loses its 
coagulability, and the same observation was made independently by Newell 
Martin. Bohr‘ obtained a similar result, on preventing the blood from 
reaching the portal circulation by occluding the thoracic aorta. The blood 
lost its coagulability in a quarter of an hour, nor was it restored for twenty-four 
hours after readmission to the abdominal viscera. This was in the dog. Ina 
rabbit, ligature of the cceliac axis and mesenteric arteries produced a similar 
but rather less pronounced effect. Delezenne has shown that artificial 
perfusion of “ peptone-blood” through the liver restores its coagulability, but 
that other organs do not produce the same result.? 

Gley and Pachon® find, in confirmation of Contejean,’ that every cause 
which diminishes or suppresses the functional activity of the liver diminishes 
or suspends the anti-coagulating action of “peptone.” They thus explain the 
experiments of Contejean, who noticed that after extirpation of the cceliac 
ganglia the action of “ pers ” is not obtained.® 

Hédon and Delezenne® also found that after the establishment of an Eck’s 
fistula (communication between portal vein and vena cava) I in the dog, and the 
subsequent removal of the liver, injection of “ peptone,” although it ‘produces 
a great fall of blood pressure, no longer removes the coagulability of the blood. 


These experiments appear to show that the liver has a special function in ~ 


connection with the maintenance of the coagulability of the blood, and that in 
passing through the lungs an effect of an opposite character is produced, but 
in what way exactly these organs exert their influence has not as yet been 
ascertained. 

Blood or plasma can be temporarily made uncoagulable in the living vessels 
by removing the fibrin. Dastre found that, if a large quantity of blood be 
drawn from an animal, and this be whipped and filtered and returned to the 
blood vessels, and the process repeated two or three times, all the fibrin can 
be temporarily removed ; and it is only gradually that the blood resumes its 
coagulability, which is not completely restored until the lapse of some 
hours. 


Conclusions regarding the causes of coagulation.—At least three 
factors appear necessary to effect the formation of fibrin, namely, 


1 Journ. Path. and Bacteriol., Edin. ee eats 1893, vol. i. p. 434. 

2 Arch. f. Physiol., Leipzig, 1887, S S. 

’ Quoted by Gad, Verhandl. d. Berl. ae Gesellsch., Arch. f. Physiol., Leipzig, 1887, 
S. 584. 

4 Centralbl. f. Physiol., Leipzig u. Wien, 1888, S. 261. 

> Compt. rend. Acad. d. sc., Paris, 11 Mai, 1896, p. 1072. 

6 Arch. de physiol. norm. et path., Paris, 1895, p. 711. 7 Thid. p. 245. 

8 Tbid., 1896, p. 159. 

® Compt. rend. Soc. de. biol,, Paris, 1896, p. 633. 


THE CAUSE OF THE COAGULATION OF BLOOD. 179 


fibrinogen, nucleo-proteid (prothrombin), and lime, and it would 
appear probable from Pekelharing’s researches that the two latter act 
in combination, and in fact represent the body which was termed by 
Schmidt the fibrin ferment (thrombin). The reason why in the healthy 
living vessels the blood does not coagulate, is, in all probability, that the 
nucleo-proteid and lime have not entered into the necessary combina- 
tion or interaction which enables them to act as a ferment upon the 
fibrinogen.? 

Of the three factors above mentioned, it is certain that fibrimogen and 
lime are both present in the plasma of circulating blood, and the problem 
therefore resolves itself into the question whether nucleo-proteid is 
present or not, or whether, if present, it is im a different condition from 
that necessary to promote fibrin formation. We may consider the latter 
question first, and in doing so it will be convenient to assume, as 
the experiments of Pekelharing seem to have proved, that the fibrin 
ferment of Schmidt is a product of the interaction of nucleo-proteid with 
lime. This conclusion of Pekelharing’s has, in fact, been confirmed by 
the researches of Hammarsten, who has shown that the nucleo-proteid 
(or prothrombin) which is obtainable from plasma is inactive as a ferment, 
except in the presence of or after it has been exposed to the action of 
soluble lime salts. It is not, however, equally clear that the fibrin 
ferment is a compound of the prothrombin with lime, as Pekelharing 
supposed it to be. 

Is fibrin ferment present in the plasma of circulating blood? As is 
well known, Schmidt’s fibrin ferment is ordinarily obtained from clotted 
blood or from serum, and the ferment-like substance used by A. 
Buchanan was also obtained by him from blood clot, and especially 
from buffy coat, 7c. the portion containing most white corpuscles. 
Schmidt found that if blood were drawn from the vessels direct into 
alcohol, no ferment could be obtained from it.2~ He came, therefore, to 
the conclusion that the blood does not coagulate in the living vessels 
owing to the absence of fibrin ferment, and that this is only formed or 
set free when the blood is drawn. Since fibrin ferment could be obtained 
in greatest abundance from the layer of the clot where leucocytes are 
most abundant, and from other tissues and organs rich in similar cells, it 
appeared probable that it is derived in drawn blood from the white 
corpuscles, and, as Schmidt believed, from their disintegration. Such 
disintegration of leucocytes was in fact described by Schmidt in drawn 
blood, but the observation has not been generally confirmed. It is not, 
however, necessary to suppose disintegration of the corpuscles, for they 
may shed out the ferment without actually undergoing disintegration. 
Now, conditions which render the blood incoagulable, such as injections 
of “peptones,” of snake venom, and nucleo-proteids in small amount, 
greatly diminish the number of leucocytes in the blood. This they do, 
however, not by causing the solution and disintegration of the corpuscles, 


1 Hammarsten, Zschr. f. physiol. Chem., Strassburg, 1896, Bd. xxii. We may dismiss 
the hypothesis of Astley Cooper (Thackrah, ‘‘ An Essay on the Cause of the Coagulation 
of the Blood,” MJed.-Chir. Rev., London, 1807, p. 191), which was revived by Briicke, 
(Brit. and For. Med.-Chir. Rev., London, 1857, and Virchow’s Archiv, 1857, Bd. xii.), that 
the living vascular walls exercise by their presence a restraining action upon coagulation, 
as having been sufficiently disproved by Lister (‘‘On the Coagulation’ of the Blood,” 
Proc. Roy. Soc. London, 1863) 

* Subsequent researches conducted in his laboratory have shown that a very small 
amount is obtainable even under these conditions. 


180 THE BLOOD. 


as supposed by Lowit! and by Wright,? but by causing their accumula- 
tion within the tissues (? capillary blood vessels). For a very short 
time after their almost complete disappearance from the blood they 
begin gradually to reappear, and in one experiment C. J. Martin found 
that the full number had reappeared within as short a time as fifteen 
minutes.? Moreover, if such disintegration really took place one would 
expect the coagulability of the blood to be visibly increased, from the 
setting free of their nucleo- proteids, whereas it is actually diminished 
or abolished. Nevertheless, those substances, such as snake venom, 
nucleo-proteids, and colloids, which in larger doses produce intravas- 
cular coagulation, may in part act by causing disintegration, if not of 
leucocytes at least of red corpuscles which also contain nucleo-proteids. 
That this occurs to some extent is shown by the fact that the serum is 
usually tinged by hemoglobin. And even without actual disintegration 
the permeability of the corpuscles may become altered, and nucleo- 
proteid shed out. 

But there is another tissue upon which the reagent in question may 
act, namely, the epithelial cells of the blood vessels. These are in all 
probability composed of living protoplasm, and the reagents may either 
cause them to shed out nucleo-proteid and so produce fibrin ferment, 
or, by deleteriously affecting them, may cause them to react upon the 
leucocytes which are passing along in contact with their inner surface, 
and effect a discharge of nucleo- -_proteid from these cells. That snake 
venom affects the blood vessels deleteriously is shown by the capillary 
hemorrhages which are so frequently seen after poisoning by it, and 
by the rapid effect it produces on the blood circulating in the mesentery, 
if a little be applied to the surface of that membrane.t The same does 
not, however, obtain with artificial colloids, nor with nucleo-proteids ; 
although, with partial blocking of the portal vein, after injection of a 
small dose, capillary hemorrhages have been found to occur in the liver.® 

The evidence which we have had before us points to the following 
conclusions regarding coagulation :— 

1. That the coagulation of blood, ze. the transformation of fibrmogen 
into fibrin, requires for its consummation the interaction of a nucleo- 
proteid (prothroml in) and soluble lime salts, and the consequent produe- 
tron of a ferment (thrombin). 

That either nucleo-proteid is not present in appreciable amount 
in the plasma of circulating blood, or that the interaction in question is 
prevented from occurring within the blood vessels by some means at 
present not understood. 

3. That the nucleo-proteid (prothrombin) appears and the interaction 
occurs, as soon as the blood is drawn and is allowed to come into contact 
with a foreign surface, the source of the nucleo-proteid being in all 
probability mainly the leucocytes (and blood-platelets 7). 

4. That, under certain circumstances and conditions, either the 
nucleo-proteid does not appear in the plasma of drawn blood, or it 
appears, but the interaction between it and the lime salts is prevented 
or delayed. 

1 “Stud. z. Physiol. u. Path. d. Blutes,” Jena, 1892. 

2 Proc. Roy. Soc. London, 1893. vol. lii. 

3 Loc. cit. 

4 Weir Mitchell and Reichert, ‘‘ Researches upon the Venoms of Poisonous Serpents,” 


Smithson. Contrib. Knowl.. W ashington, vol. xxvi. 
> Wooldridge, Trans, Path. Soc. “London, 1888, p. 421. 


: 
} 
| 
] 


CONCLUSIONS REGARDING COAGULATION. 181 


5. That the nucleo-proteid (prothrombin) appears in the plasma of 
circulating blood under certain conditions, being in all probability shed 
out from the white corpuscles and blood platelets, or in some cases even 
from the red corpuscles ; and that when shed out under these conditions 
from the corpuscles, or when artificially imjected into the vessels, it 
tends at once to interact with the lime salts of the plasma and to 
form fibrin ferment (thrombin), intravascular coagulation being the 
result. 

6. That, under other conditions, either the shedding out of nucleo- 
proteid from the corpuscles, or its interaction with the lime salts of the 
plasma, may be altogether prevented and the blood rendered incoagulable, 
unless nucleo-proteid be artificially added, or unless a modification of 
the conditions is introduced which will permit of the interaction of 
the nucleo-proteid with lime to form ferment. 

7. That the nucleo-proteid (prothrombin) is incompetent, in the 
entire absence of lime salts, to promote the transformation of 
fibrinogen into fibrin; but, as a result of its interaction with lime 
salts, it becomes transformed into a ferment (thrombin), which, 
under suitable conditions of temperature and the like, produces 
fibrin. 

8. That either the place of nucleo-proteid in coagulation may 
be taken by certain albumoses, such as those found in snake venom, 
and by certain artificial colloidal substances, such as those prepared 
by Grimaux, or that such substances may act by setting free nucleo- 
proteid from the leucocytes and other elements in the blood, or 
from the cells of the blood vessels, and thus indirectly promote 
coagulation. 


If the former supposition is the correct one, in all probability these three 
substances (nucleo-proteid, snake venom, albumose, and colloid of Grimaux) 
contain the same active molecular group.? 


LympuH, CHYLE, SEROUS FLUIDS, CEREBRO-SPINAL FLUID, SYNOVIA. 


Lymph, which is obtainable from the lymphatic vessels of the limbs, 
from the thoracic duct, and from the lacteals in the intervals of absorp- 
tion of digestive products, or from the serous cavities—although only 
occurring “normally in sufficient amount for purposes of analysis and 
experiment in the pericardial cavity—resembles generally in the char- 
acter of its constituents, but not in their relative amount, the plasma of 
the blood. Nor are the proportions of its constituents so constant as are 
those of blood plasma, for there is reason to believe that the lymph from 
different organs presents very considerable differences in their relative 
amounts. 

Lymph has generally been obtained for analysis from accidental 
lymphatic fistulee in man, from experimental fistulz in large animals, 
such as the horse, or from the thoracic duct of fasting animals (dog). 
The amount flowing along the thoracic duct is about 64 cc. per kilog. 
body weight per diem.” 


1 Halliburton and Pickering, op. cit. 
2. Heidenhain, Arch. f. d. ges. Physiol., Bonn, 1891, Bd. xlix. S. 216; Noel Paton, 
Journ. Physiol., Cambridge and London, 1890, vol. xl. p. 109. 


182 LYMPH AND ALLIED FLUIDS. E 


The following analysis is given by J. Munk and Rosenstein from a 
case of fistula of the thoracic duct in man :*— 


In 100 parts lymph— 


Total solids : 5 : 3°1=5°5 

Proteids . : : : 3°4—4-] 

Substances soluble in ether ; 0:046-0°13 

Sugar. : : : 0-1 

Salts ; ; , ; 0-8-0°9 
Nacl : F 0:55-0°58 
Na,CO, : . 0-24 


Hensen and Diinhardt2 found the following inorganic constituents :-— 
In 100 parts lymph— 


NaCl ; : ; 0-614 
Na,O : : . 0:057 
K,O ; - . 0-049 
CaO ‘ . : 0-013 
FCO: } f E ; Traces 
CO, : ; : 0-0815 
SOs || : 
P40, | 0:033 


They obtained only 0:1 per cent. of fibrin (as compared with 0-4 per 
cent. in blood plasma). This is perhaps the reason why the intravenous 
injection of peptone in small amount or ata slow rate may, as noticed 
by L. E. Shore,’ prevent the clotting of the lymph but not that of the 
plood.: The experiments of Spiro and Ellinger* seem, however, to 
indicate that, under the influence of peptone, an anti-coagulating 
substance is formed in lymph, and from this passes into the blood. 
The other proteids are also present in much less amount, but the relative 


proportion of albumin to globulin is almost exactly maintained. As. 


already stated (p. 162), the present proteid quotient is fairly constant in 
the same individual, both for blood serum, lymph serum, and serous 
effusions.» Lymph generally contains more urea than does the blood of 
the same individual. Thus in a dog Wurtz found— 


In the blood, 0°009 parts per cent. of urea. 
In the lymph, 0°016 ,, i 


The amount of sugar in lymph is about the same as in blood plasma, 
although, if dextrose be injected into the blood vessels, it soon appears 
greater proportion in the lymph than in the blood.6 Lymph contams 
a distinct amount of glycogen, but this substance is wholly contained in 
the corpuscles, and none exists in the plasma.’ 

The aqueous humour is a form of lymph, and contains the same pro- 
teid substances as lymph, namely, fibrinogen, serum globulin, serum 
albumin, and similar extractives and salts.8 It contains no corpuscles, 

1 Arch. f. Physiol., Leipzig, 1890, 8. 376 ; Virchow’s Archiv, 1891, Bd. exxiii. S. 230 
(contains a historical account of other cases). 

2 Virchow’s Archiv, 1866, Bd. xxxvii. 

3 Journ. Physiol., Cambridge and London, 1890, vol. xl. p. 561. 

4 Ztschr. f. physiol. Chem., Strassburg, 1897, Bd. xxiii. 8. 121. 

5 Salvioli, Arch. f. Physiol., Leipzig, 1881, 8. 269; Hofmann, Arch. f. exper. Path. 
u. Pharmakol., Leipzig, 1882, Bd. xvi. S. 135. 

6 The reasons for this will be considered in the article on ‘‘ Lymph Production.” 


7 Dastre, Compt. rend. Acad. d. sc., Paris, 1895, tome cxx. 
8 Halliburton and Friend, Rep. Brit. Ass. Adv. Sc., London, 1889. 


” 


CH YLE—CEREBRO-SPINAL FLUID. 183 
and does not clot spontaneously, but only on addition of fibrin ferment, 
such as is contained in serum. ‘Traces of urea are present but no sugar, 
although a slight reduction of Fehling’s solution is sometimes obtainable. 
This is probably due to paralactic acid.) 

The following analysis of aqueous humour is by Lohmeyer :?— 

In 1000 parts— 


Water 986°87 
Proteids 1,22 
Extractives 4°21 
NaCl 6°89 
Other salts 0-81 


Pericardial fiuid is a form of lymph which is found in small 
quantity within the sac of the pericardium. Peritoneal and pleural 
fluids, and the fluid of the tunica vaginalis, are not normally present in 
sufficient quantity to be collected and analysed. Pericardial fluid 
contains rather less proteid than ordimary lymph (2°28—2°55 per cent.). 

Pericardial fluid, as obtained from the horse or ox, is a yellowish 
fluid, resembling serum in appearance and in its general composition, 
but it contains fibrinogen It usually has no leucocytes, nor is it 
spontaneously coagulable, but it coagulates on the addition of ferment or 
of nucleo-proteid. 

Chyle has nearly the same composition as lymph, but it contains 
more solid matter, the increase being chiefly in fats, but also in proteids. 
The following table from Hoppe-Seyler gives its general composition in 
the dog and a comparison with the serum of the same animal. 


Chyle of Serum of 
Dog. same Dog. 
Water 90°67 93°60 
Fibrin , O-11 fe 
Albumin and globulin 2°10 4°52 
Fat, lecithin, cholesterin 6°48 0°68 
Other organic substances 0:23 0-29 
Salts 0-79 0°87 


The ether extract of chyle was found by Hoppe-Seyler to contain, 
per cent. :— 


Cholesterin 14:09 
Lecithin 8°84 
Fats TOF 


There is also, according to Hoppe-Seyler, a small amount of soap in 
chyle. The amount of urea and of sugar is about the same as in lymph. 

The cerebro-spinal fluid, although resembling lymph in its appear- 
ance, and probably in being formed by transudation from the blood 
vessels, differs from lymph chemically in certain important details. 
Although cerebro-spinal fluid is not obtainable normally in sufficient 
amount for analysis, the fluid of a meningocele appears to be nothing 
but an accumulation of the normal fluid, and has been frequently 
analysed, and the fluid of hydrocephalus has also been used for this 
purpose. Cerebro-spinal fluid as thus obtained is a clear, colourless 

1 Kuhn, Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xi. S. 200 ; Griinhagen, zbid., 8. 377. 

2 Gorup-Besanez, ‘‘ Lehrbuch,” 1878, 8S. 401. 

3 Hoppe-Seyler, ‘‘ Physiol. Chem.,” 1881, 8. 605. é 

4 For analyses of pericardial fluid from the horse, and also for the analysis of various 


dropsical fluids which tend to accumulate in the serous cavities of man, see Halliburton, 
“‘Chem. Physiol.,”’ pp. 338 and 339, and Brit. Med. Jowrn., London, 1890. 


184 LYMPH AND ALLIED FLOTDS:. 


liquid of specific gravity about 1007-8, and of a faintly alkaline reaction. 
It contains only about 1 per cent. of solids, chiefly inorganic salts, of 
which the greater part is sodium chloride, the other salts being potas- 
sium chloride, phosphates of lime and magnesia, and traces of iron and 
sulphates.1 There is, as a rule, not more than 1 part per 1000 of 
proteids. These consist almost entirely of proteoses; chiefly in the form 
of protoalbumose, which is precipitable by saturation with sodium 
‘chloride or magnesium sulphate. There is also a very small amount of 
serum elobulin, but no serum albumin or fibrinogen, nor is there any 
nucleo-proteid or fibrin ferment. Rarely peptone occurs. 

In addition to proteids and traces of nitrogenous extractives, there is 
present in cerebro-spinal fluid a non-nitrogenous substance peculiar to it, 
which has the property of reducing copper salts when heated with them 
in an alkaline solution. This was thought by Claude Bernard to be 
sugar. The substance, however, is not sugar, being non-fermentable, 
non-rotatory, and incapable of combining with pheny Ihydrazin to form 
a crystalline compound. According to Halliburton, it is pyrocatechin, 
and has the formula C;H,(OH),, being probably one of the decomposi- 
tion products of proteids ; it occurs in traces in the urine. In tapped 
cases of hydrocephalus and meningocele the amount of this substance 
increases after the first tapping? 


The presence of proteoses, and occasionally of peptones, in the cerebro-spinal 
fluid, although these substances do not oceur in blood or lymph, is of interest 
in connection with the theory of Gaskell, which supposes the central nervous 
system of vertebrates to have become developed in connection with a dorsal 
alimentary canal, such as is found in arthropods. No digestive ferment 
(pepsin, trypsin) has, however, been detected in cerebro-spinal fluid. 


Synovia differs from lymph in containing a larger amount of solids 
and also a mucin-like substance. Mucin, according to Landwehr,‘ yields 
a reducing sugar on boiling with mineral acids, but, according to Ham-_ 
marsten,? this mucin-like substance of synovia does not yield such 
reducing sugar, and is of the nature of nucleo-albumin (containing 5 per 
cent. of phosphorus). But the mucin-like material obtained by 
Salkowski? from synovia neither yielded phosphorus nor did it give 
any reducing sugar. 

Salkowski gives the following as the composition of the synovia 
analysed by hin :— 


In 100 grms.—Water . E . 93 °084, 
if Mucin-like Sie e . :, (OSTaNe 5-199 
cr Other proteids : | Aba ite 
‘ Fat : 5 ; : "282 
% Lecithin . # ; : 0-017 
as Cholesterin : . . > O:5 68% 
a Inorganic salts. : . 0°849 (Nacl 0°772) 


1 Yvon, quoted by Halliburton. 

2 For further details consult Halliburton, ‘‘ Chem. Physiol.,” p. 355; also ‘‘ Report 
of Spina Bifida Committee,” Zrans. Clin. Soc. London, vol. xviii. ; and Journ. Physiol., 
Cambridge and London, vol. x. p. 232, where the previous literature will be found. 

3 Address to the Section of Physiology, Rep. Brit. Ass. Adv. Sc., London, 1896. 

4 Arch. f. d. ges. Physiol., Bonn, Bd. 2OOOb eyes Ise 

5 Juhresb. ii. d. Fortschr. d. Thier- Chem., Wiesbaden, Bd. xii. S. 484. 

6 For analysis of synovia by different observers, see Halliburton, ‘‘Chem. Physiol.,”’ 
p- 351. 

7 Virchow’s Archiv, Bd. exxxi. S. 304. 

8 This is unquestionably abnormally high. The fluid was from a case of chronic coxitis. 


HASMOGLOBIN : ITS COMPOUNDS AND THE 
PRINCIPAL PRODUCTS OF ITS DECOMPOSITION. 


By ARTHUR GAMGEE. 


ContENts.—Distribution in the Animal Kingdom, p. 186—Relations to other Con- 
stituents of Red Corpuscles, p. 188—Arterin? and Phlebin? p, 190—Oxyhe- 
moglobin, p. 193 Methods of obtaining, p. 194—Composition of, p. 197— 
Crystalline form, p. 2 ~Action of Reagents on, p. 207—Spectrum, p. 208— 
Spectrophotometry, a Photographic spectrum, p. 225—Hzemoglobin, p. 
229— Preparation of, p- 232 Colour and Spectrum, p. 233—Compounds with 
Gases, p. 237—Derivatives and Products of Decomposition, p. 243. 


By the term hemoglobin! is designated the highly complex, iron-con- 
taining, crystalline colouring matter, which forms the most important 
constituent of the coloured “corpuscles of the blood? and in virtue of 
which they perform their function as the oxygen-carriers of the 
organism. This body possesses the remarkable property of linking 
to” itself a molecule of oxygen, so as to form an_ easily dissociated 
compound, which is termed oxyhwmoglobin, to distinguish it specifically 
from the colouring matter which has parted with its dissociable 
oxygen; for the latter some retain the name hemoglobin, though 
it is commonly, and by English writers usually, distinguished by 
the term reduced hemoglobin. 

Both oxyhemoglobin and reduced hemoglobin invariably (Hiifner) 
exist side by side in varying proportions in the living blood; the 
former being most abundant in arterial, the latter in venous, blood. 
In the present chapter the term hemoglobin will be generally employed 
when speaking of the blood-colouring matter, without specific reference 
to its relation to oxygen; the term reduced hemoglobin being invariably 
employed when reference is made to the colouring matter, deprived of 
its dissociable, or, as we may term it, in consideration of the part which 
it plays in the organism, its respiratory oxygen. 

Should we speak of “hemoglobin” or “the hemoglobins,” of 
“oxyhemoglobin” or “the oxyhemoglobins?”—In a subsequent 
section, it will be shown that the blood-colourmg matter is by no 
means absolutely identical in all animals, but that it exhibits con- 
siderable variations in certain physical characters, and in chemical 

1 Hoppe-Seyler, to whom we owe a great part of our knowledge of the blood-colouring 
matter, first suggested this term. ‘‘Um Verwechselungen zu vermeiden nenne ich das 
Blutfarbstott ‘Hemoglobulin oder Hemoglobin,’ ” Virehow's Archiv,.1864, Bd. xxix. 8. 

2 Hemoglobin constitutes about 40°4 per cent. of the weight of the moist corpuscles, 
and about 95°5 per cent. of all the organic substances contained in them. 


186 HAEMOGLOBIN. 


composition, according to the species of animal from which it has 
been derived. Based upon these facts, or perhaps in order to emphasise 
them, it is now customary with German writers, following the example 
of Hoppe-Seyler, to speak, not of “oxyhemoglobin,” but of “the 
oxyhemoglobins,” of “the heemoglobins” and not of “ hemoglobin.” 
This appears to me to be an unnecessary and misleading attempt to 
attain accuracy in scientific terminology, at the expense of true and 
philosophical conceptions. As will be shown in the sequel, the 
proportion in which iron, the characteristic element in the blood- 
colouring matter, occurs, is absolutely the same in many animals, the 
weight of the molecule being probably identical in these cases. There 
is further abundant evidence in favour of the view that the typical 
nucleus, upon which the optical and physiological properties of hgemo- 
globin depend, is absolutely identical in all animals. The grounds 
for this assertion will be given in the sequel, when it will be shown 
that the opinion advanced of recent years, as to the existence of 
several hemoglobins, not only varying in composition, but possessed 
of different powers of combining with oxygen, rests upon undoubted 
fallacies. 


DISTRIBUTION OF H&MOGLOBIN THROUGHOUT THE ANIMAL KINGDOM. 


After the discovery by Hoppe-Seyler! of the characteristic spectrum of 
hemoglobin had enabled him definitely to prove that this substance is the 
true blood-colouring matter, Kiihne ? showed that the same body is the cause 
of the red colour of the voluntary muscles of vertebrates. Hunefeld? and 
Rollett * had shown that the blood of the earth-worm and of Chironmous 
yielded crystals identical with the blood crystals obtained from other animals ; 
and Ray Lankester® and Nawrocki® simultaneously established the fact that 
these crystals consisted of hemoglobin, by examining their spectroscopic — 
characters. 

In a series of researches, which extended from 1867 to 1872, Lankester 
investigated the distribution of hemoglobin throughout the animal kingdom, 
and comparatively few facts have since been added to those which he 
published in 1872.‘ 

The following are among the principal facts hitherto ascertained in rela- 
tion to the distribution of hemoglobin.® 

Hemoglobin occurs :— 

1. In special corpuscles— 

(a) In the blood of all vertebrates, excepting Leptocephalus and Amphioxus. 


1 Felix Hoppe in Tiibingen, ‘‘Ueber das Verhalten des Blutfarbstoffes im Spectrum 
des Sonnenlichtes,” Virchow'’s Archiv, 1862, Bd. xxiii. S. 446-449 ; ‘‘ Ueber die chemi- 
schen u. optischen Eigenschaften des Blutfarbstoffs,”’ Virchow’s Archiv, 1864, Bd. xxix. 
S. 233-245. 

2 “*Ueber den Farbstoff der Muskeln,” Virchow’s Archiv, 1865, Bd. xxxiii. S. 79; 
Kiihne, ‘‘ Lehrbuch d. phys. Chemie,” 1868, S. 288. 

3“ Das Blut der Regenwiirmer,” Journ. f. prakt. Chem., Leipzig, 1839, Bd. xvi. S. 152. 

4“ Zir Kenntniss der Verbreitung des Hematins,” Sitzwngsb. d. k. Akad. d. Wissensch., 
Wien, 1861, Bd. xliy. S. 615-630. 

°** Observations with the Spectroscope,” Journ. Anat. and Physiol., London, 1867, 
S. 114. 

6 ** Optische Eigenschaften des Blutfarbstotfs,” Centralbl. f. d. med. Wissensch., Berlin, 
1867, S. 196. 

7 <*A Contribution to the Knowledge of Hemoglobin,” Proc. Roy. Soc. London, 1872, 
vol. xxi. pp. 70-81. 

8 The student is advised to read the interesting chapter, entitled ‘‘The Blood of 
Invertebrate Animals,” in Halliburton’s Text-Book, see pp. 316-330. 


HAMOGLOBIN IN THE ANIMAL KINGDOM. 187 


(In Amphioxus Lankester failed to obtain spectroscopic evidence of the pre- 
sence of hemoglobin, though Wilhelm Miiller of Jena had described the 
corpuscles of this vertebrate as of a pale red colour.) : 

(b) In the perivisceral fluid of some species of the vermian genera, 
Glycera, Capitilla, and Phoronis : 

(c) In the lamellibranchiate molluses Solen and Arca. 

2. Diffused in a vascular or ambient liquid— 

(a) In the peculiar vascular system of the chetopodous annelids, very 
generally, but with apparently arbitrary exceptions : 

(b) In the vascular system (which represents a reduced perivisceral cavity) 
of certain leeches (Nephelis, Hirudo), but not of all: 

(c) In the vascular system of certain turbellarians, as in Polia sanguirubra : 

(d) Ina special vascular system (distinct from the general blood system) 
of a marine parasitic crustacean (undescribed), observed by Professor Edouard 
van Beneden : 

(e) In the general blood system of the larva of the dipterous insect 
Chironomus ; and in Musca domestica :} 

(7) In the general blood system of the pulmonate molluse Planorbis. Mr. 
H. C. Sorby expressed the opinion that probably the colouring matter found in 
_ the blood of Planorbis is not identical with hemoglobin. I have shown, how- 
ever, that the position of the absorption-bands of the colouring matter of the 
blood of Planorbis coincides exactly with that of the hemoglobin bands :” 

(g) In the general blood system of the crustaceans Daphnia and 
Cheirocephalus (Lankester) ; also in Apus and Cypris.* 

3. Diffused in the substance of muscular tissue— 

(a) In the voluntary muscles generally of Mammalia, and probably of 
birds, and in some muscles of reptiles: 

(6) In the muscles of the dorsal fin of the fish Hippocampus, being 
generally absent from the voluntary muscular tissue of fish : 

(c) In the muscular tissue of the heart of Vertebrata generally : 

(d) In the unstriped muscular tissue of the rectum of man, being absent 
from the unstriped muscular tissue of the alimentary canal generally : 

(e) In the muscles of the pharynx and odontophore of the gastropodous 
molluscs (observed in Lymneus, Paludina, Littorina, Patella, Chiton, 
Aplysia), and of the pharyngeal gizzard of Aplysia, being entirely absent from 
the rest of the muscular and other tissues and the blood of these molluscs : 

J) In the muscular tissue of the pharyngeal tube of Aphrodite aculeata 
(Lankester), being absent from the rest of the muscular tissue, and from the 
blood in this animal, and absent from the muscular tissue generally in all 
other annelids, as far as yet examined. 

4, Diffused in the substance of nervous tissue— 

(a) In the chain of nerve ganglia of Aphrodite aculeata (Lankester). In 
this annelid the chain of nerve ganglia possesses a bright crimson colour. The 
colour is most intense in the supra-cesophageal ganglion, which has as intense 
a colour as a drop of fresh human blood. The colour impregnates the nerve 
itself, and is not contained in a liquid bathing the tissue : 

(6) An exactly similar observation has been made by Hubrecht, who found 
hemoglobin in the red-coloured cerebral ganglia of certain Nemertine worms, 
which possess no coloured blood corpuscles.* 


1MacMunn, ‘‘ Animal Chromatology,” Proc. Birmingham Phil. Soc., vol. iii. p. 
130 (quoted at second-hand). 

2 Gamgee, ‘‘A Text-Book of the Physiological Chemistry of the Animal Body,’ vol.i. p. 131. 

3 Regnard et Blanchard, ‘‘ Note sur la présence de l’hémoglobine dans le sang des 
crustacés branchiopodes,” Compt. rend. Soc. de biol., Paris, 1883, pp. 197-200. 

4A. A. W. Hubrecht, ‘‘ Untersuch. ueber Nemertinen aus dem Golf von Neapel,” 
Niederland. Arch. f. Zoologie, 1876, Heft 3, Abstract in Jahresb. ii. d. Fortschr. d. Theer- 
Chem., Wiesbaden, Bd. vi. S. 92. 


188 HAMOGLOBIN. 


THE PROBABLE RELATIONS OF THE BLOOD-COLOURING MATTER TO 
THE OTHER CONSTITUENTS OF THE COLOURED CORPUSCLES. 


Without encroaching upon the domain of histology, reference must 
be made to the two principal views which have been advanced in 
reference to the structure of the coloured corpuscles. 

According to the first,! which dates from the time of Bidloo,? Wells,’ 
and Hewson, * and which was strongly advocated by Schwann, the 
coloured corpuscles of the blood are vesicular bodies, possessmg an 
external envelope enclosing fluid contents. 

This view has been revived and strongly insisted upon by Schiifer,® 
who briefly describes the structure of the red corpuscle in the following 
sentence :—“ Each red corpuscle is formed of two parts, a coloured and 
a colourless, the former being a solution of hemoglobin; the latter, the 
so-called stroma, which is in by far the smaller quantity, being composed 
of various substances, chief among these being lecithin and cholesterin, 
together with a small amount of cell globulin.’ 6 

According to the second view, w hich, i in its present form, we owe to 
Rollett 7 and Briicke,S and which for many years found general favour, the 
coloured blood corpuscle is not considered as vesicular, but as a viscous 
solid mass composed of a colourless, highly elastic framework, the stroma 
(Rollett) denser at the periphery than at the centre, in the interstices 
or trabecule of which hemoglobin and the other constituents of the 
corpuscles are contained. 

Without attempting to decide which of these views, if either, is the 
correct one, it is expedient to consider some questions bearing upon 
them, and towards the solution of which we possess important facts. 

Making for the moment the assumption which, as will be shown in 
the sequel, is denied by Hoppe-Seyler, that oxyhwemoglobin exists as 
such in the coloured blood corpuscles, the question arises, in what 
physical state does it occur? Is it simply dissolved in the liquid 
contents of the corpuscles, or is it dissolved in virtue of its bemg in com- 
bination with other constituents? Is it ina solid condition? and if so, 
is there any evidence as to whether its structure is crystalline or 
amorphous ? 

That the colour of the blood does not depend upon a simple aqueous 
solution of hemoglobin, is evident when we consider that the blood 
corpuscles are among the soft parts of the body which contain the least 
water :® and that not only is the water which the coloured corpuscles 
contain altogether insufficient to hold the hemoglobin in solution, but im 
some animals, the hemoglobin of which is more sparingly soluble than 


1A yveference to and discussion of the earlier literature relating to this view will be 
found in Gamgee’s ‘‘ Physiological Chemistry,” vol. i. p. 72. 
2 Anatomia humani corporis, 1685,” “quoted by Milne-Edwards, ‘‘Lecons, etc.,” 
tome 1. p. 66. 

3 **On the Colour of the Blood,” Phil. Trans., London, 1797, p. 429. 

* Hewson’s Works, Syd. Soc. 

> “* Quain’s Anatomy,” 1891, vol. i. pt. 2, p. 210. 

6 Halliburton and Friend ; since shown iS be a nucleo-proteid. Pace 

 Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1862, Bd. xlvi. Abth. 2, S. 73. 
. 8 Briicke applied the term Oekoid to the stroma, ibid., Wien, 1867, "Bd. Ivi. Abth. 2 
nee 

® According to Bunge, ‘‘Zur quantitativen Analyse des Blutes,” Zischr. f. Biol., 
Miinchen, 1876, Bd. xii. S. 191, the blood corpuscles contain 36°7 parts of solids, and 63° 3 
parts of water ; muscular tissue contains about 25 per cent. of conde and 75 per cent. of 
water ; nerves contain about 22 per cent. of solids, and 78 per cent. of water. 


> 


CONDITION OF H4A:AMOGLOBIN IN CORPUSCLES. 189 


is generally the case, the whole of the water contained in the blood would 
not suffice to dissolve the hemoglobin stored up in the coloured 
corpuscles. 

That the hemoglobin is not contained in the blood corpuscles in the 
form of infinitely minute crystals, is proved by examining the corpuscles 
between crossed Nicols, when they are found not to be doubly refract- 
ing ; whilst crystals of haemoglobin, even when reduced to a state of most 
minute subdivision, are so.4 

Furthermore, no crystalline or granular structure can be discovered 
when the coloured corpuscles are examined with the highest powers of 
the microscope. 


The assumption was made by Preyer,? that hemoglobin exists in the 
corpuscles in combination with potassium, alkaline solutions possessing the 
property of dissolving much larger quantities of hemoglobin than pure water, 
and potassium being the most abundant of the mineral constituents of the 
coloured corpuscles of man, though by no means of all animals? But, as a 
matter of fact, the coloured blood corpuscles do not behave as if they contained 
free hemoglobin in a solid condition, or in solution, or a solution of an alkaline 
compound of hemoglobin. Only one proof of this statement need be given in 
this place, others being adduced when discussing the remarkable, and, as it 
appears to me, untenable proposition of Hoppe-Seyler, that the blood-colouring 
matter, as it exists in the living corpuscles, differs remarkably in properties from 
hemoglobin, so that it should be distinguished by a separate name or names. 
The one proof to which reference is made is furnished by the fact that the 
colouring matter of the red corpuscles is not extracted from them by the plasma, 
or serum, or by fairly concentrated solution of neutral salts, as would be the 
ease if they contained free hemoglobin, or an alkaline compound of that 
substance.* To explain the fact that hemoglobin is retained by the corpuscles, 
Hoppe-Seyler advanced the plausible hypothesis, that it exists in them in 
combination with some constituent of the stroma, and he expressed the opinion 
that this constituent is lecithin. There are absolutely no grounds for the 
latter assumption ; and it has indeed yet to be proved that the phosphorus-con- 
taining principle of the stroma of the coloured corpuscles is lecithin and not 
protagon, as had been very positively asserted by Hermann.° 


Without attempting to speculate beyond the facts which we possess, 
it may, however, be assumed that hemoglobin exists in the blood 
corpuscles in the form of a compound with a yet unknown constituent 
of the corpuscle. This compound, the existence of which we are forced 
to assume, is characterised by remarkable instability, for it is decomposed, 
setting free the hemoglobin, which then passes into solution—(1) when 
the blood plasma or serum, in which the corpuscles are suspended, is 
diluted; (2) when certain substances act upon the corpuscles (ether, 
chloroform, salts of the bile acids, certain products of putrefaction) ; 
(3) by the action of heat ; by alternate freezing and thawing ; by induction 
shocks, ete. 


1 W. Preyer, ‘‘ Die Blutkrystalle,” Jena, 1871, S. 28. 

* [bid., 8. 30-33. 

°G. Bunge, ‘‘ Zur quantitativen Analyse des Blutes,” Zéschr. f. Biol., Miinchen, 1876, 
Ba. x1. 8. 191. 

4 This is no real proof that hemoglobin is not in solution ; it is merely a statement of 
the fact that it is indiffusible through the unaltered envelope of the corpuscle. It is, 
moreover, capable of proof that the contents of the red corpuscles are completely fluid 
during life. Cf. p. 193, lines 9 to 12.—Eniror. 

5 Arch. f. Anat. wu. Physiol., Leipzig, 1866, S. 33. 


190 HA MOGLOBIN. 


Hypothesis of Hoppe-Seyler, that the coloured substance of the 
corpuscles possesses properties which differ from those of hemo- 
globin—Arterin (?), and Phlebin (?).—It has been shown that we are 
forced to assume the existence in the coloured corpuscles of a very unstable 
compound of hemoglobin. Hoppe-Seyler, as far back as 1877,' expressed the 
opinion that whilst the compound or compounds of hemoglobin existing in the 
blood corpuscles absorb the rays of the spectrum precisely as solutions of 
hemoglobin, in other respects very remarkable differences can be detected, 
certain of these differences being, in his opinion, of great physiological 
importance. 

Subsequently,? Hoppe-Seyler, returning to this subject, endeavoured to 
prove by a variety of arguments that such are the differences between the 
properties of the colouring matter as it exists in the coloured corpuscles and 
pure hemoglobin, that we cannot logically assert that they are identical. He 
examined in detail the differences in behaviour which had been observed by 
himself and by others, between the blood-colouring matter as it exists in the 
corpuscles and solutions of pure oxy- or reduced hemoglobin. He referred to 
the undoubted fact that the colouring matter, as it exists in the coloured 
corpuscles, is not dissolved out by serum, liquor sanguinis, or saline solutions, 
of a certain strength. It does not, he alleged, crystallise, nor readily yield 
its dissociable oxygen when heated in vacuo; it readily decomposes peroxide 
of hydrogen (H,O,), setting free ordinary inactive oxygen, and is not oxidised 
during the process; a solution of potassium ferricyanide does not for a long 
time attack the blood corpuscles, or convert their colouring matter into 
methemoglobin. 

On the other hand, a solution of oxyhemoglobin (or, as Hoppe-Seyler 
preferred to express it, of the oxyhcemoglobins, so as to recall the fact of the 
minor differences presented by the hemoglobin of different species of animals) 
is soluble in serum or in blood plasma, or in solutions of the neutral salts ; 


it crystallises with greater or less facility, according to the animal whence 


the blood is obtained. When thoroughly pure, it has scarcely any power 
of decomposing H,O,, but under the influence of this body it is readily 
oxidised. 

Solutions of crystallised oxyhemoglobin, Hoppe-Seyler maintained, give 
up their dissociable oxygen with difficulty and incompletely, when heated 
in vacuo. When blood is saturated with CO, this gas can subsequently be 
entirely removed, by passing a stream of hydrogen gas through it for some 
hours, or by long-continued boiling 7m vacuo. On the other hand, when a 
solution of oxyhemoglobin is saturated with CO, and the solution is heated 
in vacuo, the poisonous gas is, Hoppe-Seyler stated, given off with great 
difficulty and incompletely. 

Lastly, highly dilute solutions of potassium ferricyanide readily convert the 
oxyhemoglobins into methemoglobin. 

The evidence by which Hoppe-Seyler endeavoured to prove that the 
properties of the blood-colouring matter, as it exists in the corpuscles, differ so 
greatly from those of hemoglobin, that we cannot with truth say that this 
body exists in them, is, on every single point, of so unsatisfactory a character 
as not to stand a moment’s investigation, and would lead us to reject his 
hypothesis, even if we had not been placed in possession of some remarkable 
facts bearing on this subject, which have been ascertained by the method of 
spectrophotometry. The non-crystallisation of the colouring matter as it 
exists in the coloured corpuscles might, were it really true, well be explained 
by the fact that hemoglobin does not exist in a free state, but is combined 


1 “¢ Physiologische Chemie,” Berlin, 1877, Th. 1, S. 381. 
2 <¢Beitrage zur Kenntniss des Blutfarbstoffes,”” Zéschr. f. physiol. Chem., Strassburg, 
1889, Bd. xiii. S. 477. 


“ARTERIN” (?) AND “PHLEBIN” (?). IQI 


with another constituent of the corpuscle; but the statement itself, as made 
by Hoppe-Seyler, is incorrect. Although the fact has been denied by some 
writers, there can be no question whatever, on the evidence of so eminent 
an observer as Kiihne,! as well as of Funke,? Brisegger and Bruch,* Bottcher, 
Kolliker, L. Beale,t Owsjannikow,? Richardson," and Klebs, that what Preyer 
terms ‘ intraglobular crystallisation” can and does occur, 7.e. a single crystal 
forms in the interior of a coloured blood corpuscle. The process is most easily 
followed in the blood corpuscles of certain fishes,’ though it has also been 
observed in those of the dog (Kiihne) and of the rat.§ The most remarkable 
fact with regard to intraglobular crystallisation is, that when water is added 
to a preparation exhibiting it, the crystal at once disappears, and the cor- 
puscles resume their original appearance.” 

Again, at first sight, the difference in behaviour of the blood corpuscles 
and of hemoglobin towards peroxide of hydrogen appears thoroughly in 
favour of Hoppe-Seyler’s hypothesis. It was, however, shown by Bergengruen, 
who first discovered the facts in reference to H. Os that the decomposing 
action exerted by the blood corpuscles on. H,O, depends upon their stroma. 
Solutions of perfectly pure crystals of oxyhemoglobin have no action what- 
ever on peroxide of hydrogen, whilst the stroma of the coloured blood 
corpuscles exerts an intense action.® All forms of protoplasm (splenic 
cells, colourless corpuscles, yeast cells), decompose H,O,, though the stroma 
of the coloured corpuscles acts most powerfully. The fact of the decom- 
posing action being exerted by the stroma, and the stroma only, explains 
why the blood corpuscles are not oxidised whilst oxyhemoglobin is so, the 
colouring matter in the corpuscles not coming in contact with the unde- 
composed H,O,. 

The greater readiness, as compared with pure hemoglobin, with which, 
according to Hoppe-Seyler, the blood corpuscles give up either the oxygen or 
the carbonic oxide which may be combined with their colouring matter (if the 
facts were true, which we are not prepared to admit), would be much more 
probably due to a katalytic action, exerted by some other constituent of the 
corpuscle, than to any radical difference between the colouring matter of the 
corpuscles and hemoglobin. 

The one point of difference between the colouring matter of the corpuscles 
and oxyhemoglobin, which at first sight appears most difficult to explain, is 
the action of solution of potassium ferricyanide. As von eee showed, if 
fresh defibrinated blood be mixed with solutions containing 24, 5, and 10 per 
cent. of the ferricyanide, the mixture assumes a scarlet colour, and even after 
twenty-four hours contains the blood-colouring matter unaltered. On adding, 
however, the same solution of the ferricyanide, in the same proportions, to 
solutions of pure oxyhemoglobin, they assume almost instantaneously the 
colour, and exhibit the spectrum of methemoglobin. 


IW. Kiihne, Virechow's Archiv, Bd. xxxiv. 8S. 423. 

2 «Ueber Blutkrystallisation,” Ztschr. f. rat. Med., 1852, N.F., Bd. i. S. 288-292. 

3 «<Blutkrystalle, und organische Krystalle ueberhaupt” (15th Sept. and 15th Oct. 
1852), Verhandl. d. naturf. Gesellsch. in Basel, 1854-1857, Bd. i. S. 173-185. 

4<*QObservations upon the Nature of the Red Blood Corpuseles.” Quart. Journ. Mier. 
Sc., London, 1864, pp. 32-43. 

5 “Zur Histologie der Blutkirperchem,” Bull. Acad. d. se. de St. Pétersbourg, vol. viii. 
p- 561-572 (describes intraglobular crystallisation in Osmerus eperlanus). 

® “Structure of the Red Blood Corpuscles,” Philadelphia, 1870 (describes intraglobular 
erystallisation in Menobranchus). 

7 Kiihne, see W. Preyer, ‘‘ Die Blutkrystalle, ” Jena, 1871, S. 2 and 3. See also Funke’s 
** Atlas of Physiological Chemistry” (London, printed for the Cavendish Society, 1853), 
Plate x. fig. 5, and the description at p. 17 of the “ Description of the Plates.” 

8 Paul “Bergengruen, ‘* Ueber die Wechselwirkung zwischen Wasserstoffsuperoxyd und 
verschiedenen ‘Protoplasmaformen,” Inaug. Diss. , Dorpat, 1888. 

9 “Ueber die Wirkung des ferricyan. Kalium auf Blut,” Ztschr. f. physiol. Chem., 
Strassburg, 1883, Bd. viii. S. 186, 189. 


192 HEMOGLOBIN. 


The extraordinary difference in the result predisposes one at first to 
conclude that it must be due to a radical difference betwen the colouring 
matter of the corpuscles and oxyhzmoglobin, such as Hoppe-Seyler believed to 
exist. If, however, instead of the solutions mentioned above, solutions ten 
times more dilute (containing 0°25, 0°5 and 1 per cent.) be mixed with 
defibrinated blood in the same proportions as before, the mixture assumes 
instantly the colour, and exhibits the spectrum of methemoglobin. In this 
case the dilute solution extracts, in the first instance, the blood-colouring 
matter from the corpuscle, and then the ferricyanide acts upon the solution, 
exactly as it does when brought in contact with a solution of crystals of 
oxyhemoglobin. The fact that the strong solution of potassium ferricyanide 
does not act upon the colouring matter of the blood corpuscles, is due to its 
incapacity to reach, in the first instance, the oxyhemoglobin of the corpuscles. 
In this case also, it appears that the difference (supposed) between the colour- 
ing matter, as it exists in the intact blood corpuscles and solutions of heemo- 
globin, is only an apparent one. 

Though closely connected with the subject which has been discussed in 
this section, the views of Bohr! (who believes that he has succeeded in 
establishing, in addition to the already known oxyhemoglobin, the existence of 
at least three additional compounds of oxygen with hemoglobin, all possessing 
the spectrum of oxyhemoglobin, but differing in elementary composition and 
in their capacity to combine with oxygen), will be referred to under the heading 
of “Oxyhemoglobin.” There can be no question, however, that these views 
have been completely disproved by Hiifner,” the supposed individual oxyhemo- 
globins of Bohr being mechanical mixtures of pure oxyhemoglobin with 
products of its decomposition,—the necessary results of the methods of pre- 
paration followed by the Scandinavian observer. 

We have shown that even admitting, for the sake of argument, the 
correctness of al! Hoppe-Seyler’s statements, these when carefully analysed 
afford no evidence whatever in support of his bold hypothesis. Whilst such 
is the case, the splendid investigations of Hiifner? have conclusively proved 
that, in respect of its power of combining with oxygen, the blood-colouring 
matter, as it exists in the coloured blood corpuscles, behaves precisely as a 
solution of pure hemoglobin of the same concentration. Further, by the 
method of spectrophotometry, Hiifner has shown, as could be done by no 
other method, that the colouring matter of the blood 7s one—hemoglobin— 
and that in every specimen of living blood, this colouring matter exists, partly 
as oxyhemoglobin and partly as reduced hemoglobin. 

The discussion which has preceded will have prepared the reader for the 
conclusion, which appears to be the only one which can legitimately be based 
upon the facts in our possession—to wit, that whilst oxyhemoglobin and 
reduced hemoglobin exist in the coloured blood corpuscles in the form of 
loose or unstable combinations with some other constituent of the corpuscle, 
evidence is altogether wanting in support of Hoppe-Seyler’s contention that 
the blood-colouring matter, as it exists in the corpuscles, possesses properties 
so different from those of oxyhemoglobin and of reduced hemoglobin, as to 
warrant its being looked upon as a distinct substance, to be distinguished by 
a different name. Hoppe-Seyler suggested,* indeed, that the colouring matter 
of arterial blood should be called Arterin, to distinguish it from oxyhemo- 
globin, whilst that contained in venous blood should be named Phlebin, to 


1 « Ueber die Verbindungen des Hamoglobins mit Sauerstoff,” ‘‘ Ueber die specifische 
Sauerstoffmenge des Blutes und die Bedeutung derselben fiir den respiratorischen Stoff- 
wechsel,” Centralbl. f. Physiol., Leipzig u. Wien, 1890, Bd. iv. 8. 242, 254. 

2 In this place it is only necessary to refer to one of Hiifner’s papers. See G. Hiifner, 
‘‘Neue Versuche zur Bestimmung der Sauerstoffcapacitit des Blutfarbstoffs,’ Arch. f. 
Physiol., Leipzig, 1894, S. 130, 176. Refer particularly to pp. 180, 134, 175, 176. 

3 Ztschr. f. physiol. Chem., Strassburg, 1889, Bd. xiii. S, 495. 


OX VHAZMOGLOBIN. 193 


distinguish it from reduced hemoglobin! The only distinction which Hoppe- 
Seyler found to exist between “arterin” and “ phlebin ” consisted in the alleged 
greater ease with which the hypothetical constituent of arterial blood yielded 
its dissociable oxygen, when boiled in vacuo, as compared with the hypo- 
thetical constituent of venous blood. To establish this alleged difference 
between arterial and venous blood would require a body of experimental facts, 
such as does not exist. Even were the difference shown to be a real one, it 
would in no way support the hypothesis of a radical difference between the 
colouring matter of arterial and venous blood. But the investigations of 
Hiifner, which have proved with mathematical accuracy that the colouring 
matter of the blood behaves, both in so far as its optical characters and 
its relations to oxygen are concerned, precisely as a solution of hemoglobin, 
and is the only coloured constituent of the corpuscles, complete the demonstra- 
tion of the erroneous nature of the hypothesis advanced by Hoppe-Seyler 
on this subject. 


 OXYHAMOGLOBIN. 
METHODS OF PREPARATION. 


Introductory remarks.—It has already been stated that the blood- 
colouring matter of different species of animals is not, in all particulars, 
absolutely identical. Although behaving in the same manner in refer- 
ence to the gases with which it can combine to form more or less 
easily dissociated compounds, and whilst possessing identical powers of 
absorbing the rays of the spectrum, the hemoglobin of different animals 
exhibits differences (1) in crystalline form, (2) in solubility, (8) in the 
quantity of water of crystallisation, (4) in percentage composition. 
These differences will be carefully examined in the sequel, but attention 
is drawn to them in this place, in relation to another point of difference, 
namely, the variation in the facility of separating hemoglobin in a 
crystalline form. From the blood of certain animals, crystals of heemo- 
globin can most readily be prepared, whilst in other cases the task 
is one of very considerable difficulty. Among the conditions which 
influence the result, the degree of solubility of the blood-colouring 
matter is the chief. Thus the blood of the rat, the guinea-pig, and 
the squirrel, which contains the least soluble hemoglobin, yields crystals 
with great facility: whilst the blood of man, and that of the domestic 
herbivorous animals, which possess hemoglobin of remarkable solu- 
bility, yields crystals with extraordinary difficulty. It is impossible 
to state with accuracy the relative facility of crystallisation of the 
hemoglobin of different animals, but the following statements are pro- 
bably correct. The blood of the rat, the guinea-pig, and the squirrel 
erystallises most readily: next comes the blood of the cat, the dog, and 
the horse; the blood of man and the pig follow, whilst that of the 
rabbit, the sheep, the ox, and the frog erystallise with the greatest 
difficulty. 

The principle upon which the majority of the methods for the 
separation of hemoglobin in a crystalline form are based is the 
following :—To effect the solution of the hemoglobin of the coloured 
corpuscles in the serum, or in water, added to the previously separated 
corpuscles; and thereafter, by the addition of alcohol, or of ether, or 
by the agency of cold, or of both cold and alcohol or ether conjointly, 
sometimes aided by the process of evaporation, to cause the hemoglobin, 

VOL. I.—13 


194 HEMOGLOBIN. 


which is sparingly soluble in dilute alcohol, especially at low tempera- 
tures, to crystallise. In the case of animals, the hemoglobin of whose 
blood is very sparingly soluble, the addition of alcohol or ether is often 
dispensed with. We shall, in the first place, describe those methods 
which readily furnish hemoglobin crystals for the purposes of micro- 
scopical research, and then the methods which are employed for the 
preparation and purification of lar ge quantities of hemoglobin. 

Methods employed in preparing small quantities of hemoglobin 
for microscopic examination.—1. Funke’s method..—From the blood of 
those animals whose blood crystallises readily, but especially in the 
case of the rat, oxyhemoglobin can be obtained for microscopic exami- 
nation in three or four minutes, by receiving a drop of blood on a 
glass slide, adding a drop of distilled water, mixing the two liquids 
by means of a needle, and spreading the mixture over the central part 
of the slide. When the edges of the liquid commence to dry, cover 
with a microscopic covering glass. Crystals of hemoglobin form at 
once. 

2. Rollett’s method?—A platinum capsule is placed in a freezing 
mixture, and freshly defibrinated blood is poured into it, so as to convert 
it into a lump of red ice. After being in the freezing mixture for half 
an hour the blood is allowed to thaw gradually, and the contents of the 
capsule are poured into a glass vessel of such dimensions that the 
bottom is covered by the lake-coloured blood to a depth of 15 mm.; 
the glass vessel is then set aside in a cool place. In a short time, 
the blood of rats, of guinea-pigs, and of squirrels, treated by this method, 
furnishes well-formed crystals. 

Gscheidlen’s method.’—Defibrinated blood, which has been exposed 
to the air for a period of twenty-four hours, is sealed in narrow glass 
tubes (vaccine tubes answer well), and these tubes are then placed in 
the incubator and kept a temperature of about 37° C. for some days. 
On opening the tubes and emptying their contents into a watch glass or 
on a glass slide, and allowing some time for evaporation to take place, 
erystals of extraordinary size are obtained. 

4. Max Schultze’s method.—Defibrinated blood is heated (on a warm 
stage, in the case of a microscopic preparation) to a temperature of 60° F., 
when the corpuscles dissolve and the blood becomes lake-coloured ; it 
is then allowed slowly to cool and to evaporate. This method may be 
employed with large quantities of blood, and Preyer® found that by no 
other method did he obtain as fine and as large crystals from horse’s 
blood. 

In addition to the four methods which have been above described as 
most conveniently yielding crystals of oxyhzemoglobin, when these are 
desired on a small scale, there are many others which have been employed, 
and which occasionally give good results. 

Thus Rollett © found that when induction shocks were passed through 
blood, it became lake-coloured and yielded crystals of hemoglobin, and 


1 Ztschr. f. rat. Med., 1851, S. 185. 


2 «“Versuche und Beobachtungen am Blute,” Sitzwngsb. d. k. Akad. d. Wissensch., 
Wien, 1863, Bd. xlvi. S. 77. 

Spach f. d. ges. Physiol., Bonn, 1878, Bd. xvi. S. 421. 

4 «Rin heitzbarer Objecttisch und seine Verw endung bei Untersuchungen des Blutes,” 
Arch. f. mikr. Anat., Bonn, 1865, Bd. i. S. 381. 

SOC IDits Blutkrystalle,” 8. 23. 

§ Sitzwngsb. d. k. Akad. d. Wissensch., Wien, 1852, Bd. xlvi. S. 75. 


oe ta. ik 


-~ as 


ee 


PREPARATION OF OXVH4:MOGLOBIN. 195 


A. Schmidt! made the same observation in reference to the blood near 
the positive pole, when this liquid is subjected to the action of a 
constant current. 

Without undergoing any other treatment, the blood of asphyxiated 
animals often crystallises. Blood which has been deprived of its gases, 
by boiling in vacuo, often crystallises. Indeed, by this method, Preyer ? 
succeeded in the very difficult task of crystallising sheep’s blood. 

Methods of preparing considerable quantities of oxyhemo- 
globin.—Certain of the methods already recommended for the prepara- 
tion of hemoglobin, when small quantities only are needed for the 
purposes of microscopic investigation, might be employed in the pre- 
paration of larger quantities. Other processes, however, are to be 
preferred, and of these some which are specially to be recommended 
are given below. Of these processes, the first, or Hiifner’s modification 
of it, should, by preference, be employed, especially if a preparation, as 
free as possible from products of decomposition, be desired. 

Hoppe-Seyler’s method.4—Defibrinated blood is mixed with ten times 
its volume of a solution of sodium chloride® (made by diluting one 
volume of a saturated solution of NaCl with nine volumes of water), 
and the mixture is poured into shallow basins, which are set aside in a 
cool place, so as to allow the greater part of the blood corpuscles to 
settle.© The supernatant liquid is decanted, and the magma of corpuscles, 
mixed with a small quantity of water, is poured into a stoppered 
separating funnel. The contents of this funnel are treated with an 
equal volume of ether. After repeated, but not too violent, agitation, 
the deep red aqueous solution is separated from the supernatant ether, 
and filtered as quickly as possible. The clear red filtrate cooled to 0° C. 
is then mixed with one-fourth of its volume of absolute alcohol, likewise 
cooled to 0° C. The mixture is then maintained for a couple of days 
(and, if crystallisation has not occurred, even longer), at a temperature of 
—5° C. to —10° C. In a period varying between twenty-four and 
forty-eight hours crystallisation has usually occurred, and, unless the 
solution of hemoglobin was too dilute, the whole of the liquid has set into 
a mass of crystals. The crystals are now collected on a filter (the process 
of filtration being carried on at as low a temperature as possible, in any 
ease below 0° C.) and washed several times with a previously cooled 
mixture, composed of one volume of absolute alcohol and four volumes 
of distilled water. The filter with its contents is now placed between 
sheets of filtering paper, and as much as possible of the adhering mother- 
liquor is removed by gentle pressure. The oxyhemoglobin thus 


1 “Zur Krystallisation des Blutes,” Virchow’s Archiv, 1864, Bd. xxix. S. 29. 

2 “Die Blutkrystalle,” S. 19 and 20. 

® The blood of the dog, and especially of the horse, are to be preferred for the preparation 
of large quantities of oxyhemoglobin. As the success of the various operations depends 
upon their being conducted at a low temperature, the preparation of hemoglobin for purposes 
of research should only be attempted in the depth of winter. 

4 “Beitriige zur Kenntniss des Blutes des Menschen und der Wirbelthiere,” Jed. 
Chem. Untersuch., Berlin, 1866, S. 170, 180-185; ‘‘Handbuch d. physiologisch. chem. 
Analyse,” Berlin, 1893, Aufl. 6, S. 274. 

> In the preparation of hemoglobin from the blood of birds, amphibia, and fish, sodium 
sulphate is to be employed in the place of sodium chloride. In the case of mammalian 
blood, it presents no advantages over sodium chloride. 

® Instead of allowing the corpuscles to separate, as described, it is preferable to employ a 
centrifugal machine. The separation of the corpuscles from the mixture of serum and salt 
solution is not only very much more rapid, but also much more complete, and therefore the 
obtaining of pure oxyhemoglobin is facilitated. 


196 HEMOGLOBIN. 


obtained may now be purified by being recrystallised. With this object 
the moist crystals are removed by means of a spatula from the filter, 
and placed in a flask or beaker, and about three times their volume 
of distilled water is added. The mixture is heated to 55° C., the solu- 
tion filtered; the filtrate is cooled to 0° C., and to every four volumes 
one volume of absolute alcohol, cooled to 0° C., is added. The mixture 
is then cooled to —5° C. or — 10° C. 

When the oxyhemoglobin separates again, this process of erystallisa- 
tion may be repeated five or even six times, providing the temperature 
at which the various operations are conducted be a very low one. The 
recrystallised hemoglobin obtained by these processes may be employed 
to make standard solutions of the body, or it may be dried. It is very 
questionable, however, whether the recrystallising of oxyhemoglobin is 
advisable, for reasons to be stated below, it being probably better to purify 
the crystals by repeated washings with ice-cold water. Hoppe-Seyler 
states that oxyhemoglobin can only be dried, without decomposition, in 
vacuo, at a temperature under 0° C. If dried at a higher temperature it 
assumes a dark colour, and ceases to be entirely soluble in distilled water. 

Zinofisky,! who worked with oxyhemoglobin prepared from the 
blood of the horse, found that, when spread out in very thin layers, it 
could be dried ix vacuo in eight hours, without undergoing decomposi- 
tion, at a temperature of 10°C. to 20°C. He found that the oxy- 
hemoglobin thus prepared was entirely soluble in distilled water, and 
that the solution was not precipitated by lead acetate; proving that no 
methemoglobin had been formed. 

Hemoglobin which has been dried in vacuo, over sulphuric acid or 
phosphoric anhydride, at a temperature of 0° C., may be heated to 110° C. 
or 115° C., without undergoing any decomposition. 

Modifications of Hoppe-Seyler’s method —(a) Among numerous modi- 
fications may be mentioned one employed by Hiifner? and which may 
with advantage be adopted in laboratories provided with centrifugal 
machines. The blood is not treated with salt solution, but the corpuscles 
are separated by the action of the centrifuge alone. Crystals thus 
obtained are treated with ice-cold water, separated by the centrifuge, 
and this process repeated several times. Finally, the crystals are dried 
on porous plates made of cellulose, or solutions are made of the yet 
moist crystals, and the percentage of hemoglobin in them determined. 

(>) The defibrinated blood of the dog is mixed with its own volume 
of distilled water, and the diluted fluid is treated with one-fourth its 
volume of alcohol. The mixture is kept for twenty-four hours, at a 
temperature which must be lower than 0° C. The crystals which 
separate are dissolved in about three times their bulk of distilled water, 
at a temperature of 30° C., and the solution being cooled to 0° C., a 
fourth of its volume of absolute alcohol at 0° C. is added. The fluid 
should be kept in a freezing mixture at a temperature of —10° C. to 
— 20° C. for twenty-four hours. The whole fluid then becomes con- 
verted into a magma of crystals. The process of recrystallisation may 
be several times repeated. \ 

* “Ueber die Grosse des Hiimoglobin-moleciils,” Ztsehr. 7. physiol. Chem., Strassburg, 
1886, Bd. x. S. 15-34. See ‘* Darstellung des Hiimoglobins,” S. 18-24. 
* Beitrag zur Lehre von Blutfarbstotfe,” Beitr. z. Physiol. C. Ludwig z. s. 70 Geburtst. 


etc., Leipzig, 1887, S. 74-81; and ‘‘ Neue Versuche, u.s.w.,” Arch. f. Physiol., Leipzig, 
1894, S. 134-136. 


PURIFICATION OF HA;MOGLOBIN. 197 


(c) Defibrinated blood is treated with about one-sixteenth its 
volume of ether (say 31 ¢.c. of ether to 500 cc. blood), and the mixture 
shaken for some minutes. It is then set aside in a cool place. After a 
period, varying from twenty-four hours to three days, the liquid has 
been converted into a thick magma of crystals. These may be separated 
by placing in tubes and using the centrifugal apparatus. The cakes of 
erystals are treated with a mixture of one part of absolute alcohol and 
four parts of distilled water, and again centrifugalised. By repeating 
this process the crystals are ultimately obtained free from serum 
albumin. The crystals may be dissolved in water and recrystallised, as 
described in Hoppe-Seyler’s method. 

In addition to the methods described, many others have been 
suggested, and to these only a passing reference need be made. 

Thus Kiihne devised a method based upon the fact that the stroma 
of the coloured corpuscles is dissolved by the addition of a watery 
solution of crystallised: bile (a mixture of sodium glycocholate and 
taurocholate). Hiifner? and his pupil Otto employed a 1 per cent. 
alcoholic solution of chinoline, or a watery solution of the hydrochlorate 
of the same base, to prepare oxyhzemoglobin from pig’s blood, though 
Otto afterwards found? that, by taking special precautions, Hoppe-Seyler’s 
method is available, even in the case of pig’s blood, and indeed preferable 
to all others. 


Remarks on the purification of hemoglobin.—It has, until lately, 
been assumed that in the preparation of pure oxyhemoglobin the body should 
be recrystallised as frequently as possible, with the object of getting rid of all 
traces of adherent albuminous and saline impurities derived from the plasma 
or serum. Since spectrophotometry has supplied us with a method of deter- 
mining, with an accuracy previously unattainable, the purity of a colouring 
matter, it has been found that although oxyhemoglobin which has been 
recrystallised, when examined in the ordinary manner, exhibits a spectrum 
which appears identical with that of the colouring matter which has been only 
once crystallised, its spectrophotometric constants have changed; in other 
words, when oxyhemoglobin is recrystallised it undergoes a change, possibly 
only affecting its physical, but more probably affecting its chemical constitution 
also. The knowledge of these facts has caused Hiifner in his recent researches 
to employ hemoglobin which has not been recrystallised. 

If precautions are taken in the first instance to separate (by the most perfect 
filtration, followed by prolonged centrifugalising) all formed elements and acci- 
dental solid impurities from the solution of blood corpuscles which is to be 
crystallised, and if the crystalline mass of oxyhemoglobin obtained be repeatedly, 
say five or six times, treated with ice-cold water, the resulting solution being 
each time separated from the undissolved crystals by very rapid and very 
prolonged centrifugalising, the portion of the original crystals still left undis- 
solved will be found, on chemical, microscopical, and spectrophotometric 
investigation, to furnish evidence of being a pure substance. 

The new method is more easily and much more expeditiously carried out 
than the old. 


Elementary composition of oxyhzemoglobin dried at 110°-115° C. 
—Before describing either the physical or chemical properties of the 


1 Centralbl. f. d. med. Wissensch., Berlin, S. 833. 

2 The account of Hiifner’s discovery of this method is contained in a paper by his pupil, 
F. Otto, ‘‘ Ueber das Oxyhimoglobin des Schweines,” Zéschr. f. physiol. Chem., Strassburg, 
1882-83, Bd. vii. S. 57 


198 H#EMOGLOBIN. 


blood-colouring matter, it is advisable to consider its elementary com- 
position, and to ascertain how the results of chemical analysis bear on 
the question as to hemoglobin being a definite chemical individual, its 
composition being invariable. 

Hemoglobin is a compound of carbon, hydrogen, nitrogen, sulphur, 
iron, and oxygen. The crystals of hemoglobin contain water of crystal- 
lisation, which varies considerably in amount in the hemoglobin of 
different animals. When ignited, pure hemoglobin obtained from 
mammalian blood yields an ash composed entirely of ferric oxide; the 
‘hemoglobin of birds and fishes, and probably of all animals with 
nucleated corpuscles, yields on ignition an ash which, in addition to 
Fe,O,, contains phosphoric anhydride (P,0,), derived in all probability 
from nuclein contained in the corpuscles. 

The earlier analyses of oxyhemoglobin made by C. Schmidt? and 
by Hoppe-Seyler® exhibited results which appeared to indicate that 
crystallised oxyhemoglobin is a body of constant composition. From 
the analyses of these two observers, and his own determinations of the 
iron and sulphur in crystallised oxyhemoglobin, Preyer deduced the 
following as the mean percentage composition of oxyhemoglobin :— 


In 100 Parts. 


C 54°00 
H 7:25 
N 16°25 
Fe 0-42 
S 0°63 
O 21:45 

100-00 


On the assumption, which a large number of facts have since shown 
to be almost certainly correct, that the molecule of hemoglobin contains 
one atom of iron, Preyer assigned to it the empirical formula CoooH goo 


9999 


N,5,FeS,0,7, the molecular weight being 13,332. 


Analysis of Oxyhemoglobin dried at a temperature above 100° C.* (Hoppe-Seyler). 


| 
Water of Crystallisa- 
. ata tion in the Crystals | a | 
Oxyhemoglobin of eaTGhiind carmel EE | Nel Oe Ss. Fe. POs, 
dried in vacuo. 


Dory: : : 3-4 per cent. 53°85 | 7°32 | 16°17 | 21°84] 0°39 | 0°43 
Goose . Tsp yy 54226 | 7°10 1 16:21 20°69) ) 07545) Oar) ian 
Guinea-pig . ‘ ORE nies: 54°12 | 7°36 | 16°78 | 20°68 | 0°58 | 0°48 

4 


Squirrel .  . 9 ,, 4, | 54°09] 7°39 | 16-09 | 21°44] 0-40 | 0-59] ... 


1Y. Inoko, ‘‘ Einige Bemerkungen ueber phosphorhaltige Blutfarbstoffe,” Zéschr. /. 
physiol. Chem., Strassburg, 1894, Bd. xviii. S. 57. 

*“* Analyse der Blutkrystalle,” in Bottcher’s monograph, ‘‘ Ueber Blutkrystalle,” 
Dorpat, 1862. 

3“ Beitrige zur Kenntniss des Blutes des Menschen und der Wirbelthiere ; Zusammen- 
setzung der Farbstoffkrystalle des Meerschweinchen- und des Hunde-blutes,” Med. Chem, 
Untersuch., Berlin, 1868, S. 186 ef seq. 


ELEMENTARY COMPOSITION OF OXVH4MOGLOBIN. 199 


The subsequent researches of Hoppe-Seyler soon demonstrated, 
however, that the blood crystals obtained from the blood of different 
animals did not possess an identical composition, though the differences 
brought out by Hoppe-Seyler’s analyses were not very great. His 
results are shown in the table on p. 198.4 

The very numerous analyses of oxyhzmoglobin of different animals, 
made in recent years by Kossel,? Otto,? Zinoffsky,t Hiifner,> Jaquet, 
and others exhibit, however, such extraordinary discrepancies in the 
results of ultimate organic analysis as to preclude a precise answer 
being given to such simple questions as the following :— 

Is hemoglobin a body, having a constant composition in animals 
of the same species ? 

Does the hemoglobin of different animals vary in chemical com- 
position, and if so, within what limits ? 


Results of the more recent Analyses of Oxyhenoglolin (1878-1890). 


Oxyhzemoglobin of C. H. | N. | S. Fe, oO. P.O;. 
| | 
Dog. : . | 53°85 | 7°32 | 16°17 | 0°39 | 0°43 | 21°84 |... Hoppe-Seyler.? 
cae te : - | 53°91} 6°62 | 15°98 | 0°540 | 0°333 | 22°62 | ite Jaquet.® 
ee | 54°57 | 7°22 | 16°38 | 0°568 | 0°336 | 20-93 526 Jaquet. 
Horse | 54°87 | 6°97 | 17°31 | 0°650| 0°47 | 19°73 sa || Kossel-10 
af | 54°76 | 7°03 | 17°28 | 0°67 | 0°45 | 19°81 nae Otto. 
5 54°40 | 7:07 | 17°40] 0°66 | 0°45 | 19-74 sis Biicheler.” 
sae 51°15 | 6°76 | 17°94] 0°39 | 0°335 | 23°43 | ... Zinofisky. 8 
xa”. 54°66 | 7°25 | 17°70 | 0°447 | 0°400/19°54 | ... Hiifner. 4 
ee 1% 4: LU ea Ors oGklbers.: wey Abts: Hiifner.” 
Pig . 54°17 | 7°38 | 16°23 | 0°660 | 0°430 | 21-360 Laven Otto.6 
ees 54°71] 7°38 | 17°43 | 0-479 | 0°399 | 19°602)_... Hufner.!7 
Hen. 52°47 | 7°19 | 16°45 | 0°857 | 0°335 | 22°500 | 0°197 | Jaquet.}§ 


1 Med. Chem. Untersuch., Berlin, 1868, Heft 3, S. 370. 

* The results of the analyses made by Dr. Kossel were published in a paper by Hoppe- 
Seyler, entitled ‘‘ Weitere Mittheilungen ueber die Eigenschaften des Blutfarbstotfs—Das 
Oxyhamoglobin des Pferdeblutes,” Zéschr. f. physiol. Chem., Strassburg, 1878-79, Bd. ii. 
S. 149-155. 

3 ** Ueber das Oxyhimoglobin des Schweines,” ibid., 1882-83, Bd. vii. S. 57-68. 

4 “Ueber die Grosse des Hiimoglobinmoleciils,” ibid., 1886, Bd. x. S. 16-34. 

5 “Ueber das Oxyhiimoglobin des Pferdes,” Ztschr. f. physiol. Chem., Strassburg, 
1883-84, Bd. viii. S. 358-365; ‘‘ Beitrige zur Lehre vom Blutfarbstoffe,” in Beitr. 2. 
Physiol. C. Ludwig z. s. Geburtst. etc., Leipzig, 1887, S. 74-81; ‘‘ Neue Versuche zur 
Bestimmung des Sauerstoffscapacitat des Blutfarbstoffs,” Arch. f. Physiol., Leipzig, 1894, 
S. 130-176. See especially 8. 174-176. 

6 «*Blementaranalyse des Hundeblut-Hamoglobins,” Zéschr. f. physiol. Chem., Strass- 
burg, 1888, Bd. xii. S. 285-288; Beitrage zur Kenntniss des Blutfarbstoffes,” 7bid., 
1890, Bd. xiv. S. 289-296. 

7 This analysis, which is adduced for purposes of comparison, does not fall within the 
dates given above, having been published in 1868. 

8 Zischr. f. physiol. Chem., Strassburg, 1888, Bd. xii. S. 285. 

9 Tbid., 1890, Bd. xiv. S. 289. 

10 Tbid., 1878-79, Bd. ii. S. 149. Refer to Note 2. 

1 Arch. f. d. ges. Physiol., Bonn, 1884, Bd. xxxi. S. 240. 

2 Hiifner, Zitschr. f. physiol. Chem., Strassburg, 1883-84, Bd. viii. S. 358. This paper 
contains the results of Biicheler’s researches, which have been carried out under Hiitner’s 
direction, and had appeared as a Tiibingen Dissertation in 1883. 

8 Tbid., Strassburg, 1886, Bd. x. S. 16. 

4 Beitr. z. Physiol. C. Ludwig z. s. Geburtst. etc., Leipzig, 1887, S. 74. 

1 Arch. f. Physiol., Leipzig, 1894, S. 174. 

16 Zischr. f. physiol. Chem., Strassburg, 1882-83, Bd. vii. S. 57. 

W Beitr. z. Physiol. C. Ludwig z. s. Geburtst. etc., Leipzig, 1887, S. 74. 

8 Ztschr. f. physiol. Chem., Strassburg, Bd. xiy. 8S. 289. 


200 HAEMOGLOBIN. 


Were we to admit the accuracy of the work of all the observers, 
whose results are exhibited on the table on p. 199, we should be forced 
to the conclusion that hemoglobin is a body which does not only vary 
considerably in composition in different animals, but does not possess a 
constant composition even in different individuals of the same species. 
Thus, whilst Kossel found the percentage of carbon in the oxyhemoglobin 
of the horse to be 54:87, and the mean of a large number of analyses 
by Kossel, Otto, and Biicheler gave 54°68, Zinoffsky, as a result of his 
analyses (only two in number, so far as the carbon and hydrogen are 
concerned !), found the percentage of carbon in the hemoglobin of the 
horse to be 51:15 (!!).. A body in which the carbon differs by 3°72 per 
cent. in different specimens cannot, it will be argued, be a chemical indivi- 
dual. But to draw this conclusion in reference to heemoglobin from the 
facts in our possession would certainly be an error. The discrepancies 
between the results of the analyses of the hemoglobin of the same 
animals are doubtless due to differences in the purity of the substance 
analysed, and to errors of analysis. The preparation of perfectly pure 
oxyhemoglobin, entirely free from contamination with other con- 
stituents of the blood corpuscles and from products of decomposition, is 
much more difficult than has, until very recently, been supposed. In 
the attempt to purify the substance by crystallising it as frequently as 
practicable, nearly all observers have in all probability decomposed it, 
and have afterwards analysed a mixture of oxyhzemoglobin and products 
of its decomposition. How far this is the source of the above discrep- 
ancies must now, in the lght of recent spectrophotometric work, be 
carefully enquired into. Moreover, assuming that perfectly pure crystal- 
lised oxyhzemoglobin is at the disposal of the analyst, the task of drying 
without decomposing it is one of peculiar difficulty, concerning the 
method of execution of which the chemists who have carried out the 
researches under discussion have been by no means agreed. Thus, whilst 
some (following Hoppe-Seyler’s directions) have dried the oxyhemoglobin 
intended for analysis, in the first instance in vacuo at 0° C., and only 
afterwards at higher temperatures, others (Zinoffsky, Hiifner, Jaquet) 
have dried the substance in vacuo at ordinary temperatures (15° to 
18° C.), and subsequently at 110° to 115° C. 


It is conceivable, nay probable, that some of the differences in the results 
of different observers may have depended upon the above-mentioned differ- 
ence in the treatment of the substance analysed. But, unquestionably, some 
of the best marked differences must depend upon differences in the 
method of analysis employed (e.g. where one observer determines the N in 
oxyhemoglobin by Will and Varrentrapp’s method, whilst another employs 
Dumas’ method), and upon accidental errors of analysis, which can easily be 
rendered obvious, by making a considerable number of analyses. 

For instance, it appears to me that the percentage of carbon given by 
Zinofisky,! as representing the proportion of this element in the hemoglobin 
of the horse, must be due to imperfect combustion. Whilst this observer 
carried out the determinations of iron and sulphur in the hemoglobin of the 
horse in the most elaborate and perfect manner, making many analyses of 
each of three separately prepared specimens of crystallised hemoglobin, he 
rested satisfied with only two determinations of carbon and hydrogen, and 
two determinations of nitrogen (the latter by the method of Will and 

1 “Ueber die Grosse des Himoglobinmoleciils,” Ztschr. f. physiol. Chem., Strassburg 
1886, Bd. x, 


ELEMENTARY COMPOSITION OF OX VYHAMOGLOBIN. 201 


Varrentrapp), though the results which he obtained differed in a remarkable 
manner from all those of previous observers. It is clear that whilst very great 
value must be attached to the determination of the iron and sulphur contained in 
hemoglobin, made by Zinoffsky, his conclusions as to the percentage of carbon 
and hydrogen must be rejected, as being based upon an insufficient number 
of analyses, and as being in all probability incorrect. This opinion is supported 
by the remarkable discrepancy between his results and those of other observers 
—a discrepancy which cannot be accounted for by differences in purity of the 
bodies analysed. 

While it is almost inconceivable, and against the weight of evidence, that 
hemoglobin derived from animals of the same species should not have a 
constant composition, the differences in centesimal composition which certainly 
do exist between the hemoglobin of certain animals and that of others 
cannot surprise us when we reflect that hemoglobin does exhibit marked 
physical differences in different animals—that it exhibits variations in 
erystalline form, in the amount of water of crystallisation, and in solubility. 


The study of the general results of the ultimate analyses of oxy- 
hemoglobin made of recent years forces us assuredly to the conclusion 
that new and still more precise investigations are needed before we can 
lay claim even to so limited a knowledge as that of its precise centesimal 
composition. Nevertheless, it would be wrong to leave the study of 
the more recent researches without drawing attention to certain of the 
numerical results obtained, which are more deserving of confidence 
than others. 

The most characteristic and the most important of the elements 
which enter into the composition of hemoglobin is its iron. Iron is 
the typical element in a molecular group which exists and possesses 
identical chemical and physical properties in all the varieties of 
hemoglobin with which we are acquainted. Besides furnishing us 
with data by which the molecular weight of hemoglobin may be 
calculated, the amount of iron appears to bear a definite relation to 
the quantity of the dissociable oxygen and carbonic oxide which 
hemoglobin combines with. For these reasons, an extremely accurate 
determination of the iron in hemoglobin, carried out with all the 
precision which the present state of science permits of, has been a great 
desideratum. Such determinations have been carried out by Zinoffsky, 
Jaquet, and Hiifner (see p. 199). 


| 
| Hemoglobin of Fe percent. | Authority. 
|. 
Dog : : | 0°336 _ Jaquet. 
Horse : ie 0°335 Zinofisky. 
Obs: : 3 4 0-336 Hiifner. 
Hen ; ae 0-336 Jaquet. 
; ara 


These observers have determined the proportion of iron in the 
oxyhemoglobin of the dog, the horse, the ox, the pig, and the hen. 
They have shown: First, that the amount of iron in the blood-colouring 
matter of these animals is decidedly smaller than had been assumed 
on the basis of the older analyses. Secondly, that in: the animals 
mentioned the percentage of iron in the hemoglobin is identical, so 


that we may conclude that in these very different animals, in spite of 


202 HEMOGLOBIN. 


the discrepancies between the results of the ultimate organic analyses 
yet made, the oxyhemoglobin possesses the same molecular weight. 
The ‘concordance between the more recent determinations of the iron 
of oxyhemoglobin is well shown in the table given on the previous 
page. 

On the assumption that one molecule of HEaGe EA contains one 
’ atom of iron, the molecular weight of the hemoglobin of the dog, horse, 
ox, and hen would be 16,669,and this result is borne out, as will be 
afterwards shown, by the volume of oxygen or of carbonic oxide which 
enters into combination with the blood-colouring matter. 

In addition to the estimation of the iron im hemoglobin, that of 
the sulphur has been carried out with remarkable care by Hiifner,} 
Zinoffsky, and Jaquet; and their results, whilst establishing that the 
centesimal composition of the blood-colouring matter of all animals is 


not identical, show that in hemoglobin the sulphur stands to the iron” 


in definite relations. 

Thus Zinoffsky’s analyses appear to establish that in the hemoglobin 
of the horse the sulphur is to the iron in the relation of two atoms of 
the former to one of the latter element, and Hiifner has shown that 
exactly the same relation obtains in the case of the hemoglobin of the 
ox and the pig. On the other hand, Jaquet’s analyses of the hemo- 
globin of the dog indicate that in it three atoms of sulphur correspond 
to one atom of iron. When, in a subsequent section, we shall examine 
the products of decomposition of hzemoglobin, we shall show that, under 
the influence of acids and alkalies, the blood-colouring matter breaks 


up into an iron-containing body (of which the composition and the - 


properties vary according to the presence or absence of oxygen during 
the decomposition) and into an albuminous body or bodies. The 
sulphur of hemoglobin belongs to the albuminous part of the molecule, 
and the difference in the relation of S to Fe, brought out by the 
researches of Hiifner, Zinoffsky, and Jaquet indicates that the albuminous 
moiety of the hemoglobin molecule varies in different animals, and that 
among the points of difference is the difference in the proportion of 
sulphur. This point will be certainly cleared up by future researches 
specially directed to its elucidation; it may be remarked, however, 
that the proportion of sulphur in different albuminous bodies does 
exhibit great variations. 

It appears to me, moreover, that we must not lose sight of the possi- 
bility (even when there is no evidence afforded by ultimate organic 
analysis of there being a difference in the percentage composition of the 
albuminous part of the hemoglobin moiety), and indeed probability, that 
hemoglobins varying tm certain physical properties may be formed by the 
linking of the iron-containing molecule to various polymeric combinations of 
the same albuminous molecule. 

Although it is highly probable that the molecular weight of the 
hemoglobin of the dog and of the ox (16,669), as determined by the 
iron determinations of Jaquet and Hiifner, and by determinations by 
Hiifner of the volumes of O and CO with which hemoglobin combines, 
has been ascertained with correctness, or nearly so, the discrepancies in 
the results of the determinations of C, H, and N, made by different 
observers, are too great to warrant our placing confidence in the 
empirical formule which have been assigned to hemoglobin. Of these 

1 “ Bestimmung d. Sauerstoffscapacitit d. Blutfarbstoffs,” S. 76. 


— 


CRYSTALLINE FORM OF HAMOGLOBIN. 203 


empirical formule, that calculated by Jaquet for the hemoglobin of the 
dog is probably the nearest the truth, namely— 


{ { 1 
Crsel Tsing N ps3 © Oars 


Why should hemoglobin possess so enormously high a molecular 
weight? The question suggested itself to the acute mind of Bunge, who 
has “furnished us with one reason which is eminently suggestive: “The 
enormous size of the hemoglobin molecule,” says this writer, “finds a 
teleological explanation, if we consider that iron is eight times as heavy 
as water. A compound of iron, which would float easily along with the 
blood current through the vessels, could only ae secured by the iron 
being taken up by so large an organic molecule.” 

When discussing the compounds and ae of decomposition of 
oxyhzmoglobin and hemoglobin, we shall have again to revert to and 
further examine certain of the facts which have found a place in this 
section. 

The crystalline form, inne amount of water of crystallisation, the 
solubility, and the diffusibility of oxyhemoglobin.—Although, as has 
already been stated, the oxyhemoglobin of different animals varies con- 
siderably in the facility with which it crystallises, we now know that the 
hemoglobin of all animals, without exception, may, by suitable treat- 
ment, “be obtained in the crystalline form.? Great differences exist in 
the solubility of the blood-colouring matter obtained from different 
animals, and, as might have been anticipated, the blood of these 
animals whose hemoglobin is least soluble (as the rat, the guinea-pig, 
and the squirrel) ) yields crystals of oxyhemoglobin most readily ; whilst 
the converse is also true, 7. the oxyhemoglobin of man, of the rabbit, 
the sheep, and the ox, all of which are exceedingly soluble, yield crystals 
with considerable difficulty. It was, indeed, long supposed to be impos- 
sible to obtain large quantities of oxyhemoglobin from the blood ot 
certain of these animals. 

As a rule, crystals of oxyhemoglobin are of such a size that their 
form, and even their crystalline nature, cannot be made out by the 
naked eye. The blood of certain animals, however, as the dog, and 
particularly the horse, yields under favourable circumstances rhombic 
prisms of macroscopic size. From horse’s blood Hoppe-Seyler frequently 
obtained prisms over 5 mm. in length and 4 mm. in thickness. The 
colour of erystals of oxyhemoglobin appears different, according to 
their size or the number aggregated together.t Thus the finest needles 
or prisms of oxyhemoglobin, when seen singly under the microscope, 
appear almost colourless, or possess the yellowish tint characteristic of 
the coloured corpuscles. On the other hand, large crystals, or consider- 


1 From the results of Hiifner’s analyses of the hemoglobin of the ox, but substituting 
his most recent determinations (1894) of the iron for the older ones, published in 1887, 1 
have calculated for the hemoglobin of this animal the formula— 


CrsoHicosNaroS2KeOuo, 


2G. Bunge, ‘‘ Text-Book of Physiological and Pathological Chemistry.” Translated by 
L. G. Wooldridge : London, 1890, p. 24. 

3Tt was Dr. Otto Funke who first asserted, as the result of his own researches, ‘‘ that 
all blood is capable of crystallisation, whatever animal or organ it may be taken from.’-— 
‘Explanation of the Plates” of his ‘‘ Atlas of Physiological Chemistry,” .p. 15 (see p. 205, 
note 1). 

4. Hoppe-Seyler, ‘‘Das Oxyhimoglobin des Pferdeblutes,” Ztschr. f. physiol, Chem., 
Strassburg, 1878-79, Bd. ii, S. 149, 


204 HAEMOGLOBIN. 


able aggregations of the smaller crystals, exhibit, like aggregations of 
blood corpuscles, the red colour characteristic of the blood. 

We shall now examine successively the most important facts con- 
nected with the (1) form, (2) quantity of water of crystallisation, 
(3) solubility, presented by crystallised oxyhzemoglobin, (4) diffusibility. 

1. Form.—(a) The blood ‘of man and of the immense majority of 
‘animals yields oxyhzemoglobin which crystallises in rhombic prisms or 
needles belonging to the rhombic system. 

(b) The oxyhemoglobin of the guinea-pig presents crystals which 
were described by Lehmann as regular octohedra. They were, however, 
shown by the eminent crystallographer v. Lang! to be tetrahedra 
belonging to the rhombic system. 

The blood of certain birds,? and occasionally apparently of the 
rat 3, +, °, yields crystals of the same form. 

(c) The oxyhemoglobin of the squirrel crystallises normally in the 
form of six-sided plates belonging, as proved by v. Lang, to the hexagonal 
system. These crystals had been first described by Lehmann and Kunde. 
The blood of the hamster (Cricetus vulgaris) contains oxyhemoglobin 
which ecrystallises, as Lehmann showed, in rhombohedra and six-sided 
plates belonging to the hexagonal system. Halliburton,® who has studied 
the crystallography of oxyhemoglobin with great care, has made the 
interesting observation that “after recrystallising squirrel’s hemoglobim 
several times the hexagonal constitution of the er ystals is broken down, 
and the crystals obtained are either rhombic prisms or a mixture of 
these with rhombic tetrahedra.” 


Rollett,’ taking for granted that oxyhemoglobin, from whatever source 
obtained, possessed the same chemical composition, argued, from the fact of 
its crystallising generally in the rhombic, but in the case of the squirrel in the 
hexagonal system, that oxyhemoglobin should be looked upon as dimorphous. 

Halliburton, however, with perfect correctness, hesitates to admit this 
view, which could only be held if we were certain that the hemoglobins whose 
crystals belong to different systems possess identical composition, and suggests 
that perhaps the difference in the crystalline form, as well as the difference in 
solubility of the hemoglobins which crystallise differently, depends upon 
varying quantities of water of crystallisation—that, in fact, the hemoglobins 
which crystallise in different systems represent ‘ different hydrates of oxy- 
hemoglobin.” § This may be the case, though it appears to me that the cause 
of the difference lies deeper. 

It has been previously stated—and the grounds for the statement will be 
given in a subsequent section—that, notwithstanding the perplexingly dis- 
cordant results of the analyses of oxyhemoglobin, there is, in the hemoglobin 
of all animals, absolute identity of the essential iron-containing nucleus, 2.e. 


1In a paper by A. Rollett, entitled ‘‘Versuche u. Beobachtungen am Blut, nebst 
krystallographisch. u. optisch. Mittheilungen ueber die Blutkrystalle von Vv. Lang,” 
Stieungsb. d. k. Akad. d. Wissensch., Wien, 1862, Bd. xlvi. S. 66-98. 

Halliburton, ‘‘Text Book of Chemical Physiology,” London, 1891) 820: 

> + Kunde, Lehmann, see Preyer, ‘‘ Die Blutkrystalle,” S. 38. 

2 ’ Hoppe- Seyler, “Ueber die Kr ystallformen der Blutkrystalle,” Med. Chem. Untersuch., 
Berlin, 1868, S. 195. 

& “Preliminary Communication on the Hemoglobin Crystals of Rodents,” Jowrn. 
Physiol., Cambridge and London, 1886, vol. vii. p. 2; Quart. Journ. Micr. Sc., London, 
vol. xxviii. p. 181. 

7 Loc cit. 

* Halliburton, ** Text Book of Chemical Physiology,” section on the ‘Crystallography of 
Oxyhemoglobin,” pp. 270-274. The student is recommended to read this interesting and 
suggestive section. 


+P) 


THE WATER OF CRYSTALLISATION. 205 


of that moiety of the molecule on which its colour and its physiological func- 
tion depends. At the same time, there is such a difference in the ratio of 
S:Fe in the hemoglobin of certain animals as renders it highly probable, or 
rather certain, that, in the hemoglobin of different animal groups, the albu- 
minous moiety of the complex molecule differs. Such being the case, it is not 
surprising that certain of the physical characters of hemoglobin, such as 
erystalline form and solubility, should exhibit variations.!. Nor can we lose 
sight of the possibility, to which I have already drawn attention, that the 
differences in the hemoglobins of certain animals may be due to their being 
formed by the linking of the iron-containing molecule with different polymers 
of the same albuminous group. The existence of hemoglobins varying some- 
what in their percentage of iron renders this view highly probable. 


2. Quantity of water of crystallisation. — Remarkable difficulties 
encounter the observer in his attempts to determine the amount of 
water of crystallisation of oxyhemoglobin, and considerable discrepancies 
are to be noticed in the results obtained by different processes. 

In order to make the determination, pure oxyhemoglobin is dried 
im vacuo at 0° C., and after ceasing to lose weight under these conditions 
it is heated to a temperature of 115° C. 

The following are some of the principal and most reliable results 
obtained :— 


| Water of 
Oxyhemoglobin. Crystallisation | Authority. 

per cent. | 

| | 
Dog. : : : - | 3°4 Hoppe-Seyler. | 
Horse, . ‘ : sah] 3°94 Hiitner. 
Bie’ : : : lt) 59 Otto. 
Guinea-pig | 6 Hoppe-Seyler. 
Squirrel 9 | Hoppe-Seyler. 


According to Bohr,” the water of crystallisation of oxyhemoglobin may 
vary in amount between 1°2 and 6°3 per cent., but these results, like others 
obtained by the same author, and to which reference has been made (see p. 
192), are explicable by the fact that his preparations of hemoglobin did not 
represent the pure substance, and contained products of decomposition. 


Without taking Bohr’s results mto consideration, there can be no 
doubt that crystals of oxyhemoglobin of different animals exhibit 
differences in the amount of water of crystallisation. Assuming the 
above results to be correct, the highly soluble oxyhemoglobin of the 
pig, which erystallises in rhombic prisms, possesses the same amount of 
water of crystallisation as the very sparingly soluble oxyhemoglobin of 
the guinea-pig, separating in the form of tetrahedra. 

3. Solubility.— The difficulties which encounter the observer in 


1 The reader is referred to an admirable account of all the researches on the Crystal- 
lography of Hemoglobin, up to the date of its publication (1871), to the chapter entitled 
‘‘Krystallformen des Blutroths,” in Preyer’s work, ‘‘ Die Blutkrystalle.” Very fine 
coloured engravings of the hemoglobin crystals of various animals—amongst others, of 
man, the guinea-pig, and the squirrel—are to be seen in Funke’s ‘‘ Atlas of Physiological 
Chemistry,” being a Supplement to Lehmann’s ‘“‘Physiological Chemistry,” London, 
printed for the Cavendish Society, 1853. See plate x. and pp. 15-17 of the appended 
letterpress. 

2 “Exp, Untersuchungen ut. die Sauerstoffaufnahme des Blutfarbstoffes,” Copenhagen, 
1885. 


206 HAEMOGLOBIN. 


determining the water of crystallisation of the blood-colourmg matter 
are surpassed by those attending the estimation of its solubility. It is 
doubtless in some measure due to the difficulty, almost the impossibility, 
of eliminating every trace of certain of the reagents (especially the 
alcohol), employed in the preparation of the body, that any attempts 
to determine with precision the solubility of oxyhemoglobin have 
failed. The chief cause of the discrepancies between the observations 
of different observers is, however, probably that they were unaware 
of the physical, and perhaps also chemical, changes which hemoglobin 
undergoes in the process of recrystallisation. 

The oxyhemoglobin of all birds, of the ox, of the pig, and of man 
is distinguished by its great solubility, the relative e solubility increasing 
in the above order. Next in order of solubility comes the hemoglobin 
of the horse, dog, squirrel, guinea-pig, and rat, the latter being certainly 


the least soluble. 


According to C. Schmidt, 100 grms. of water at 18” C. dissolve 15°59 grms. 
of the crystallised oxyhemoglobin of the dog. From the fact that the oxy- 
hemoglobin analysed by C. Schmidt when ignited yielded on an average 0°91 
per cent. of P,O,, we are in a position to state that the body he experimented 
with was very impure, and consequently that his estimate of its solubility in 
water possesses no value. Hoppe-Seyler found that 100 c.c. of water at 
5° C. dissolved 2 germs. of the dry oxyhemoglobin of the dog. 

Lehmann found that one part of the dry crystallised oxyhemoglobin of 
the guinea-pig required 597 parts of water to dissolve it, but the temperature 
at which the determination was made is not stated ;! moreover, it is more 
than doubtful whether the substance experimented with was pure. 


The present state of our knowledge permits us, therefore, to state 
that the oxyhemoglobin of different animals differs in no property so 
remarkably as in its solubility in water. It appears, further, that oxy- 
hzemoglobin—which, according to the more recent researches, contains 
the same percentage of iron (that of the horse, ox, dog, and pig), and 
therefore presumably possesses the same molecular weight, and which, 
further, crystallises in the same manner—exhibits marked differences in 
solubility. As the oxyhemoglobins of the horse and of the dog seem, 
in so far as the water of crystallisation is concerned, to be identical, 
and as the researches of Hiifner and his school have proved the identity 
of the iron-containing part of the molecule in the hemoglobin from the 
most different animals, we are, it appears to me, driven to the con- 
clusion that the difference in solubility must be due to differences in 
the albuminous residue in the hemoglobin molecule. 

Solubility in liquids other than water—Oxyhemoglobin is soluble in 
highly diluted solutions of ammonia, and the other caustic alkalies, and 
their carbonates. These solutions resist decomposition much longer 
than aqueous solutions of hemoglobin2 Kiuhne states that a highly 
dilute ammoniacal solution of oxyhemoglobin will remain in great part 
unchanged for several weeks at ordinary temperatures. ” Stronger 
solutions of the caustic alkalies or their carbonates induce decom- 


1 W. Preyer, ‘‘ Die Blutkrystalle,”’ S. 55. 

2 Based upon these facts is the method, introduced by Hiifner, of diluting blood or 
solutions of oxyhemoglobin with solutions containing 0°1 per cent. of NaOH. Such 
solutions are much more transparent than purely aqueous solutions, and are therefore 
most valuable for the purposes of spectroscopic researches. 


ACTION OF REAGENTS ON OX YHA7MOGLOBIN. 207 


position of oxyhemoglobin with a rapidity which depends upon their 
concentration. 

Oxyhemoglobin is soluble in highly diluted alcohol, the solutions 

resisting putrefaction much jotige than aqueous solutions. By contact 
with even highly dilute alcohol, crystals of oxyhemoglobin become much 
more sparingly soluble in water. Oxyhemoglobin i is insoluble in absolute 
aleohol. When crystallised oxy hemoglobin i is treated with a large excess 
of absolute alcohol, it is under favourable circumstances converted into an 
insoluble crystalline modification, to which Nencki and Sieber have 
given the name of parahwmoglobin This body cannot be looked upon 
as a chemical individual. Oxyhemoglobin is insoluble in chloroform, 
benzol, and carbon disulphide. 

4. Diffusibility—Oxyhemoglobin offers a remarkable example of a 
soluble crystalline body, which, judged by its power to pass through a 
septum of parchment paper, must be declared to be absolutely non- 
diffusible. This character depends upon the enormous size of its 
molecule. 

Comparison of the action of certain reagents on solutions of 
oxyheemoglobin and on solutions of albuminous bodies.—It has 
already been incidentally stated that in hemoglobin an iron-containing 
body is linked to an albuminous body or bodies, and reference has been 
made to the fact that, under the action of various agents, oxyhemoglobin 
breaks up into the iron-containing hematin, and into albuminous bodies. 
Although the decomposition of hemoglobin and its products will be con- 
sidered in some detail in a future section, it is convenient in this place 
to refer to this point, and to state that when oxyhemoglobin is decom- 
posed so as to yield hematin and albuminous substances, the former 
amounts approximately to 4 per cent. and the latter to 96 per cent. of 
the original hemoglobin. 

Such being the case, it is of particular interest to contrast the 
action of certain reagents on solutions of albuminous bodies, and on 
solutions of oxy hemoglobin. 

Solutions of oxyhwemoglobin differ remarkably from solutions of 
albuminous bodies in their behaviour towards a large number of 
reagents. 

As Kiihne pointed out long ago,? all those tests for albumin which 
do not immediately bring about a decomposition of oxyhzmoglobin, 
furnish a negative result when applied to aqueous solutions of this 
body. Cupric and ferrous sulphates, mereuric chloride, silver nitrate, 
neutral and basic acetates of lead, all of which precipitate albuminous 
solutions, occasion (so long as the body remains undecomposed) no pre- 
cipitate—not even cloudiness—when added to solution of oxyheemo- 
globin. So soon, however, as the red colour of oxyhemoglobin has 
disappeared under the action of any one of the above salts, and the 
brown colour due to hematin has appeared (a result which they all 
sooner or later bring about), the characteristic albuminous precipitates 
appear. 


1M. Nencki und N. Sieber, ‘‘ Untersuch. ueber die Blutfarbstoff,” Ber. d. deutsch. 
chem. Geselisch., Berlin, 1885, Bd. xvill. S. 392; M. Nencki und B. Lachowitz, ** Ueber das 
Parahiimoglobin,” ibid., Bd. xviii. S. 2126. The reader is referred for a criticism of Nencki 
and Sieber’s researches on parahemoglobin, to a paper by Hoppe-Seyler, entitled ‘‘ Ueber 
Blutfarbstoffe und ihre Zersetzungsproducte,” Zischr. 7. physiol. Chem., Strassburg, 1886, 
Jbjels say (SEG ME 

2 «*Tehrbuch der physiolog. Chemie,” Leipzig, 1866, S. 207. 


208 HAMOGLOBIN. 


Other reagents which bring about an instant decomposition of 
oxyhemoglobin, and, consequently, instantly set free the albuminous 
matter, exhibit also, as might have been anticipated, the characteristic 
albumin reactions, ae. behave towards a solution of hemoglobin as if 
it were a solution of a native albumin. This remark applies to acetic 
acid and potassium ferrocyanide, to mercuric nitrate, to the concentrated 
mineral acids—reagents, all of which precipitate a solution of oxyhemo- 
globin as they do solutions containing albuminous bodies. 

When subjected to the action of heat, solutions of oxyhemoglobin 
coagulate like solutions of the native albumins; but, doubtless, before 
the temperature of coagulation (64° to 68°5 C.) is reached, the complex 
hemoglobin molecule has already been decomposed —a supposition 
which is suggested by the following observation :1—If to an aqueous 
solution of crystallised oxyhemoglobin of the dog a small quantity 
of sodium carbonate be added, on applying heat no coagulation occurs, 
even though the temperature be raised to 100° C. When, however, the 
temperature reaches 54° C., the colour of the solution instantly changes to 
deep brown, and spectroscopic examination indicates that the spectrum 
of oxyhemoglobin has been replaced by that of alkaline hematin. 


THE ABSORPTION OF LIGHT BY OXYHAMOGLOBIN. 


(a) The visible spectrum.—Historical notes.—The researches of 
Brewster and Herschel had shown that absorption-bands occur in the 
spectrum of light which has been passed through certain coloured gases, 
vapours, and coloured solutions, and the so-called absorption spectra of indigo 
and chlorophyll had been described before the time when Hoppe? made the 
discovery of the beautiful absorption spectrum of blood, distinguished by 
two very characteristic absorption-bands, situated in the region which inter- 
venes between the lines of Frauenhofer, D and E. 

This discovery at once enabled Hoppe to affirm that hematin, which had 
up to that time been generally looked upon as the true blood-colouring matter, 
does not exist as such in the blood corpuscles, but that it is a product of the 
decomposition of the colouring matter ; that the latter, to which he afterwards 
gave the name of hemoglobin, and which he recognised as forming the so-called 
blood crystals described by Kunde, Lehmann, and Funke, is the cause of the 
absorption-bands which he had discovered in the spectrum of diluted blood, 
and that this colouring matter, under the influence of heat, acids, and various 
other chemical agents, splits up into hematin and an albuminous substance or 
substances. 

There can be no question that, although Hoppe, in a certain measure, 
appreciated the immense value of the knowledge which he had gained by his 
study of the optical properties of the blood, the full light which it was 
destined to shed on the function of the blood-colouring matter was only 
recognised when Professor Stokes, two years later, published his paper “On 
the Reduction and Oxidation of the Colouring Matter of the Blood.”* The 
new facts acquired by the combination of chemical and optical methods in 
this research, and which at once shed a flood of light on phenomena which 
had until then been shrouded in darkness, enlisted as workers in this field 

1 Preyer, ‘‘ Die Blutkrystalle,” S. 61. 

2 Hoppe only assumed the name of Hoppe-Seyler in 1864. The paper containing 
his first observations on the spectrum of the blood bore the following title :—Professor 
Hoppe in Tiibingen, ‘‘Ueber das Verhalten des Blutfarbstoffes im Spectrum des 
Scnnenlichtes,” Virchow’s Archiv, 1862, Bd. xxiii. S. 446-449. 

3 Proc. Roy. Soc. London, 1864, vol. xiii. p. 357. 


VISIBLE SPECTRUM OF OX VYHA:MOGLOBIN. 209 


many persons of distinction in all countries, amongst the first and most 
successful of whom were W. Preyer! in Germany, and Sorby and Ray 
Lankester in England. Amongst all, however, who by their work have 
contributed to the spectroscopic investigation of the blood, two appear to 
me to stand out pre-eminently—these are Vierordt and Hufner. by the dis- 
covery of the first practical method of determining the extinction-coefficient 
of coloured liquids, and his elaboration of a general method for the 
quantitative analysis of colouring matters, a method capable of surprising 
refinement and accuracy, and which is based upon the relation which exists 
between the extinction-coefficient and concentration, Vierordt has placed 
both the sciences of physics and physiology under a lasting obligation.” 
To Hiifner belongs the merit of having developed and perfected the 
methods of spectrophotometry, but especially of employing it so as to obtain 
results of paramount importance to physiology, and which would have been 
unattainable without its aid. Not only has he, by his own long-continued 
researches, and those of his pupils, determined the spectrophotometric con- 
stants of hemoglobin and its compounds with oxygen and carbonic oxide, 
but he has by spectrophotometry succeeded in determining the absolute 
and relative amounts of reduced and oxyhemoglobin existing side by side 
in the blood. He has further shown that, as we now know the volume of 
oxygen which can combine with | grm. of hemoglobin, by determining the 
amount of hemoglobin and of oxyhemoglobin coexisting in any specimen of 
blood, we possess data enabling us to calculate the volume of the dissociable 
or respiratory oxygen of the blood, without having recourse to direct deter- 
minations by means of the mercurial pump and gas analysis. 

Further, by the method of spectrophotometry, combined with the results 
of chemical investigation, Hiifner has furnished us with the proof that, in 
spite of the differences in many physical characters, and even in centesimal 
composition presented by the blood-colouring matter of different animals, the 
coloured iron-containing group existing in hemoglobin, upon which its essen- 
tial physiological functions depend, is identical in all.* 

General description of the visible spectrum of oxyhzemoglobin. 
—Instruments required.—For the study of the visible, as distinguished from 
the photographic spectrum of the blood, or of oxyhemoglobin, the spectro- 
scopes which are in common use in physical and chemical laboratories may be 
employed, providing the dispersion of their prisms be not too great. A 
spectroscope of the ordinary Bunsen type, provided with a single good flint- 
glass prism, is infinitely to be preferred for the study of absorption spectra to 
an instrument with two prisms, for, with the greater dispersion, absorption- 
bands appear much less clearly defined than with the smaller. Direct vision 
spectroscopes of the Browning or Hofmann patterns, or microspectroscopes, 
z.e. direct vision spectroscopes adapted to the eyepiece of the compound 
microscope, may be employed; and the second class of these instruments 
renders great services in the investigation of minute quantities of colouring 
matters—as, for instance, in the examination of the optical characters of 
the colouring matters of the tissues. 

It is advisable, indeed for the purposes of original research indispensable, 
that the spectroscope employed should furnish means of determining accur- 


1 Preyer’s monograph, entitled ‘‘ Die Blutkrystalle,” which appeared in Jena in 1871, 
still continues indispensable to the physiological chemist. It is replete with original 
observations of great value, and establishes that Preyer had no unimportant share in the 
development of our knowledge of the blood-colouring matter. 

2 Karl Vierordt, ‘‘ Die Anwendung des Spektral-apparates zur Photometrie der Absorp- 
tionsspektren und zur quantitativen chemischen Analyse,” Tiibingen, 1873; ‘‘Die 
quantitative Spektralanalyse in ihrer Anwendung auf Physiologie, Physik, Chemie, und 
Technologie,” Tiibingen, 1876. 

3 As the chief of Hiifner’s papers have been already quoted, or will be referred to sub- 
sequently in detail, their dates and titles are not given in this place. 


VOL. I1.—14 


210 HAEMOGLOBIN. 


ately the position of any line or the boundaries of any absorption-band 
observed in the spectrum, it being usual to express the position in terms of 
the wave length of the light corresponding to it. With this object the 
spectrum of sunlight is observed, and the position of the principal lines of 
Frauenhofer is determined in reference to the divisions of the photographic 
scale, or, in the case of the finer spectroscopes and spectrometers, in reference 
to the divisions of the graduated circle of the instrument. From the results 
of these observations a curve is readily plotted, enabling the experimenter at 
any time to convert the readings of the arbitrary scale of his instrument into 
wave lengths.! 

For all exact spectroscopic work the eyepiece of the spectroscope should 
be provided with cross-threads ; and, when employed in the investigation of 
absorption spectra, if possible with the arrangement employed in  spectro- 
photometry, which enables the observer to limit, by a variable slit in the 
eyepiece, any particular spectral region and to shut out of the field of view 
the remainder of the spectrum. 

As a source of light, for some investigations the light of the sun reflected 
from the mirror of a heliostat driven by clock-work is desirable ; for general 
purposes the light of the sun, reflected from a white surface, may be employed. 
Artificial sources of illumination possess the great advantage of being available 
at all times, and susceptible of considerable constancy. A gas lamp, furnished 
with the Auer incandescent burner, is the best of all lamps for the examina- 
tion of absorption spectra. 

In examining the absorption-spectra of liquids, it is convenient to employ 
cells or troughs with perfectly parallel glass or quartz sides, which are a 
definite width apart. Such vessels are made according to the model of 
Hoppe-Seyler, and sold under the name of hematinometers (Fig. 23), the 
internal surface of the parallel glass plates being exactly 1 cm. apart, and the 
little trough being so arranged as to be readily taken to pieces for cleaning. 
The small troughs employed in spectrophotometry, and which are usually 
constructed with great care, are well adapted to the general purposes of the 
spectroscopist. 

Instead of a vessel of which the sides are at a constant and known dis- 
tance apart, it is convenient for many purposes to employ the so-called 
hematoscope, or hemoscope, of Hermann,? as shown in the accompanying 
woodcut (see Fig. 24). F is a glass plate, forming the anterior wall of the 
tube D, which is supported on the stand A. C is a metallic tube, sliding in 
and out of the tube D, and closed anteriorly by a glass plate parallel to F. E 
is a funnel communicating with the interior of D F B. By sliding the piston 
C in and out of the tube D, the capacity of the vessel D F B and the 
depth of a stratum of liquid contained between the two glass plates, may be 
modified at will within wide limits. 

The depth of the stratum is read off by the aid of a millimetre scale, 
engraved on the sliding tube C. 

As the absorption of light passing through a coloured liquid depends 
upon the number of absorbing molecules in its path, by doubling the thick- 
ness of the stratum of a coloured liquid examined, we obtain the same result 
as by examining a solution of double concentration. With such a contrivance 
as the hematoscope, we are, within certain limits, able therefore to obtain the 
same result with a solution of constant concentration as with a large number 
of solutions of which the concentration varies in known proportions. 


' In a work intended for the advanced student of physiology, it appears superfluous to 
enter into such details concerning the construction of the spectroscope, or the method of 
working with it, as can be learned in all courses of practical physics, or may be found in 
any elementary treatise devoted to this branch of science. 

2“ Notizen fiir Vorlesungs und andere Versuche,” Arch. f. d. ges. Physiol., Bonn, 
Bd. iv. S. 209. 


VISIBLE SPECTRUM OF OX YHAMOGLOBIN. 211 


The spectrum as seen with solutions of varying concentration.— 
When well-arterialised defibrinated blood (containing on an average 
from 12 to 14 per cent. of oxyheemoglobin) is diluted with nine times 
its volume of distilled water, and a stratum 1 em. thick is brought before 
the slit of the spectroscope, it will be found that the whole of the 
spectrum is absorbed, with the exception of the red end, or rather of 
those rays having a wave length greater than about 600 millionths of 
a millimetre (% 600). 

If, now, the blood solution be gradually diluted, a point is reached 
at which the spectrum is (proceeding from the red end) clear up to D 
(a 598), and a strip of green is visible between 4 and F (4 518°3—1 486:1). 
Between D and } the absorption is intense (see Plate I, Spectrum 4), 
and beyond F no trace of light appears. On diluting still further, that 


AU AT LT 


iq 


Fic, 23.—The hematinometer. Fic. 24.—The hematoscope. 
which appeared as a single wide absorption-band between D and 0, and 
afterwards as the solution was progressively diluted between D and E, 
is seen to resolve itself into two distinct absorption-bands, separated by 
a green interspace; the violet end of the spectrum is still powerfully 
absorbed (Plate I., Spectrum 3). 

Of the two absorption-bands just referred to, the one next to D is 
narrower than its fellow; it has more sharply defined borders, and to the 
eye appears more tntense; its centre corresponds to ~ 579, and we may 
conveniently distinguish it as the absorption-band « in the spectrum of 
oxyhemoglobin. 

The second of these absorption-bands, ze. the one next to E, which 
we shall designate the band £, is broader, has less sharply-defined edges, 
and its centre corresponds approximately to 25538. Between the two 
bands is a green interspace. 

On diluting the solution more and more largely, and continuing to 
examine a stratum 1 cm. thick, the absorption of the violet end becomes 


212 HAMOGLOBIN. 


less and less, and the whole spectrum as far as G appears beautifully 
clear, except where the two absorption-bands are situated (Plate L, 
Spectrum 2). If dilution be pushed still further, these disappear; before 
they vanish they appear as faint shadows across the limited region which 
they occupy. The band « is said to disappear last. I find, however, that 
whenever I can detect « I am able to detect a faint shadow in the 
position of % 540-2 550. When the bands are just perceptible, there is 
no obvious absorption of either the red or the violet end of the spectrum. 

The two absorption-bands of oxyhemoglobin are seen in greatest 
perfection when a stratum 1 cm. thick of a solution containing 1 part 
per 1000 of oxyhemoglobin is examined; this corresponds to a solution 
made by diluting from 1:2-1-4 parts of blood to 100. They are still 
perceptible when the solution contains 1 part oxyhzemoglobin in 100,000 
parts of water (1 grm. in 10 litres). 


* 


OXYILEMOGLOBIN. H£MOGLOBIN. 


| 
ABG D Eb F atene ABG D ‘EommE Goals 


Fic. 25.—Graphic representation of the spectrum of oxyhemoglobin and 
hemoglobin. The numbers on the right are percentages.—After 
Rollett. 


The above figure illustrates a method of representing graphically 
the variations in the spectrum of the blood-colouring matter, correspond- 
ing to all concentrations (a stratum of 1 ¢.c. being examined).t 

In these diagrams the position of the principal Frauenhofer lines 
is shown; the numbers on the right indicate percentages of the blood- 
colouring matter. The shaded part of the diagram indicates absorp- 
tion of light. By drawing lines parallel to the abscissee we at once 
observe the character of the absorption spectrum which corresponds 
to the concentration indicated at the right-hand side of each diagram. 
Thus, by inspection of the left-hand diagram, we learn that solutions of 
oxyhemoglobin, containing more than 0°65 per cent., exhibit a single 
broad absorption-band in the visible spectrum, owing to the fact that 
the two absorption-bands « and @ have run together, and that the 
green interspace between ) and F is shown only by solutions of less 
concentration than from 08 to 0-9 per cent. When the absorption of 
this part of the spectrum is complete, only orange and red remain 
unabsorbed. 

By placing the solution of oxyhzemoglobin in a wedge-shaped cell, 


1 A. Rollett, ‘‘ Physiologie des Blutes,”” Hermann’s ‘‘ Handbuch,” Leipzig, 1880, Bd. iv. 
Th. 1, 8. 48. 


THEORY. & METHODS OF SPECTROPHOTOMETRY. 213 


the slit being perpendicular to the edge of the wedge, the accuracy of 
the diagram can be realised objectively, each section of the slit forming 
a spectrum corresponding with a given thickness of stratum, which 
increases in a continuous manner from the edge towards the base of the 
wedge. This method of examination was first employed by J. H. Glad- 
stone.t 

The theory and methods of spectrophotometry.—The spectro- 
photometric constants of oxyhemogilobin-—(a) The theory.—Inte- 
resting and attractive though it undoubtedly is, the examination of an 
absorption- -spectrum, or the comparison of allied absor ption-spectra, by 
the unaided sense of sight, may be singularly deceptive. 

The impression which the unaided eye enables us to form of the 
boundaries, the breadth, the intensity of an absorption-band, or of the 
extent and depth of a less defined general absorption, is often very 
fallacious. When, for instance, the absorption of a definite region of the 
spectrum commences and ceases abruptly, the band appears to the eye 
more intense than when the absorption commences and ceases more 
gradually.2. The most striking illustration of the truth of these remarks 
is indeed furnished by the two oxyhemoglobin bands. The first, less 
refrangible band («), has always been described as much more intense 
than the second, which is broader and less sharply defined, and un- 
questionably this is the impression which we form by ordinary methods 
of examination. Vierordt*® has, however, shown that, in opposition to 
the visual impression, a greater percentage of light is absorbed in the 
spectral region which corresponds to the second band than in that 
corresponding to the first band. Measuring, spectrophotometrically, the 
percentage of light remaining unabsorbed, after traversing a stratum 1 cm. 
broad of a solution containing 1 per cent. of defibrmated mammalian 
blood, he found that in the region of the first, apparently more intense 
band, 87 per cent. of the light was absorbed and 13 per cent. trans- 
mitted; whilst in the region of the second, apparently less intense band, 
90 per cent. of the light was absorbed, and only 10 per cent. transmitted. 

This result at once suggests the necessity of a method of determin- 
ing quantitatively the amount of light absorbed by any medium whose 
absor ption-spectrum forms the subject of investigation, instead of tr usting 
to our unaided sense of sight. When, however, we are made acquainted 
with the remarkable and far-reaching conclusions which can be legiti- 
mately drawn from an accurate determination of the percentage of ght 
of a definite wave length, absorbed by colourmg matters existing in 
solution, the beauty and the importance of the method of spectr ophoto- 
metry become apparent. Until Vierordt’s discovery, those coloured 
bodies whose visible spectrum presented no definite absorption-bands, 
were held to be beyond the scope of spectroscopic research. Now, how- 
ever, we know that a photometric study of the spectrum affords us not 
only the means of identifymg them, but supplies us with a method 
for the quantitative analysis of colouring matters, surpassing all others 
in accuracy, and permitting, in certain cases, of the accurate determination 
of data not to be ascertained in any other way. 

1J. H. Gladstone, ‘‘On the Use of the Prism in Qualitative Analysis,” Journ. Chem. 
Soc., London, 1858, vol. x. p. 79. 
ae pero ‘* Physiologie des Blutes,”” Hermann’s ‘‘ Handbuch,” Leipzig, 1880, Bd. iv. 

ola. 50: 


3 «Tie Anwendung des Spektral-apparates zur Photometrie der Absorptionsspektren,”’ 
Tiibingen, 1873. 


214 HEMOGLOBIN. 


1. Relation between the concentration of a solution and the percentage 
of light absorbed by it.—Before investigating the theory of the methods 
of spectrophotometry, to be subsequently “described, it is essential to 
examine (1) the relation which exists between the power of light 
absorption exerted by a coloured liquid of constant composition and the 
. thickness of the layer traversed; (2) to study the influence of concen- 
tration on the absorption of light by a stratum of a liquid holding a 
colouring matter in solution. 

It was shown by Lambert that if light of intensity /, by transmission 
through one layer of an absorbing medium of thickness 1, has its in- 


i JE se 
tensity reduced to 7 aS by transmission through d such layers, the 


Jinal intensity of the light, which we shall represent by JZ’, will be re- 
duced to aa ee im = Beer showed that Lambert’s law holds good, 
not only for transparent solid media, but also for liquids, ze. that the 
amount of light absorbed by a solution of a given colouring matter of con- 
stant concentration is dependent upon the thickness of the stratum. This 
law is only true, however, in respect to monochromatic light. 

We must now examine the influence of the concentration of a liquid 
containing a colourmg matter in solution upon the percentage of light 
which it absorbs and transmits, when the stratum examined remains of a 
constant width, 1. It has been experimentally proved that the absorp- 
tion exerted by a stratum of a coloured solution of known width is 
equal to that exerted by a stratum twice as thick of a solution of half 
the concentration ; i.e. the absorption which light undergoes im passing 
through a stratum of coloured liquid of unit thickness tnereases propor- 
tionally to the concentration. 

2. Definition of the “ extinetion-coefficient.”—In their photo-chemical 
researches, studying the comparative absorption of light by different 
gases, Bunsen and Roscoe? introduced the conception of, and defined, 
the so-called extinction-coeficient. They ascertained the relative thick- 
nesses of the strata of various media required to reduce the intensity 
of light passed through them to one-tenth of its initial value, and defined 
the extinction-coefficient as the reciprocal of the number expressing the 
width of the stratum of a given medium, required to reduce the intensity of 
light passed through it to one-tenth its initial value. 

For any given coloured medium, ¢.g. a solution of a colouring matter 
of a definite strength, there must be a definite thickness of layer which 
we shall call d, capable of reducing the intensity of light to one-tenth 


: we bag! 
its original value. The reciprocal of d is Pe and if by ¢ we represent 


the extinction-coefficient, 
i 
d 

As will be shown in the sequel, the method of spectrophotometry 
discovered by Vierordt rests upon the determination of this constant ¢, 
for particular, very limited, regions of the spectrum. The practical diffi- 
culties of varying the thickness of the stratum of a coloured liquid, until 


=> 


1 When the thicknesses of various strata increase in arithmetical, the intensities of 
the light decrease in geometrical, ratio. 
2 Ann. d. Chem., Leipzig, 1857, Bd. ci. S. 238. 


THEORY & METHODS OF SPECTROPHOTOMETRY. 215 


the intensity of the light remaining unabsorbed is reduced precisely to 
one-tenth, would be extremely great. Fortunately, the coefficient of 
extinction can be determined in a manner presenting far smaller practical 
difficulties and admitting of great accuracy. 

If, instead of varying the thickness of the stratum of the coloured 
solution until the initial intensity of the light entering it is reduced to 
one-tenth its value, we invariably examine in our photometric investi- 
gations a stratum of unit width (say 1 em.), or a stratum of known 
width, and possess the means of estimating the proportion of ight which 
remains unabsorbed, we possess data enabling us to calculate the ex- 
tinction-coefficient. 


1 1 
_ and that ¢= ? and when «=d, 


Ve 
logy Te... 
3 


It was previously shown that /’ = 


[=75. Then log l’=— =z log and d log n=1.°.e=log n=— - 
so that, if the thickness of the stratum traversed by the light be known, 
and the intensity of the unabsorbed light J’ ascertained, the coefficient 
¢ can be calculated. But if « be of the constant value 1 (say 1 cm.), 
then ¢ = — log J’; that is to say, the extinction-coeficient is equal to the 
negative logarithm of the unabsorbed light. Let us suppose that by pass- 
ing through a stratum of coloured solution 1 cm. wide, the intensity of 
light has been reduced to two-thirds its original value, then 


») 


= — log 5 = log 3 — log 2 
== 0176092 

3. Definition of the term “ absorption relation.” —It has already been 
stated (see previous page) that the more concentrated a coloured liquid, 
the greater its absorbing power, the smaller, therefore, is the width of 
the stratum required to reduce the intensity of the light passed through 
it to one-tenth of its initial value. ‘As the extinction-coefficient is, by 
definition, the reciprocal of the thickness of the stratum required to 
bring about this result, it follows that the greater the concentration of 
the solution, the greater will be the extinction-coefficient ; in other words, 
the extinction-coefficient ¢ and the concentration ¢ are proportional. 
Let ¢ and ¢’ represent the concentration of two coloured solutions, of 
which the extinction-coefticients are ¢ and ¢ respectively, then 


/ 


6 Mee. ic 


and c= _= 
Epa: 
ie. the relation of the concentration of a coloured solution to its extinction- 
coefficient is a constant, represented by A, and termed the “ Absorption- 
relation” (Absorptionsverhdltniss, Vierordt). Upon the determination of 
this constant rests Vierordt’s method of quantitative spectrophotometric 
analysis. If we have, in the case of a solution of a particular body, 
determined by analysis its concentration c,and then with the spectro- 
photometer determined its extinction-coefficient for a particular spectral 
region, and thus obtained the value of A, we can find out how much 
of the same substance is contained in a solution of unknown strength 
(c’) by merely determining ¢’, according to the equation: 
Cae 


216 HAMOGLOBIN. 


It is usual to determine the value of the constant A of any coloured 
body under examination for, at least, two spectral regions. The reasons 
for this practice will appear in the sequel. 

(b) The actual methods of spectrophotometry.—The elementary theo- 
retical discussion of the theory of spectrophotometry which has preceded has 
shown that, as developed by Vierordt, it resolves itself into the determination 
of the extinction-coefficient and of the absorption relation of coloured bodies, 
and that the optical investigation is concerned with, and confined to, the 
determination of the value of « | We have now to consider the two principal 
methods by which this determination can be effected. 

Vierordt’s method.—For the determination of the extinction-coefficient 
according to the original method of Vierordt, any good spectroscope of the 
type introduced by Bunsen for laboratory purposes may be employed, provided 
certain modifications and additions are made. The most essential of these 
modifications consists in replacing the usual single slit of the collimator by a 
double slit, z.e. by a slit composed of two independent halves—an upper one 
and a lower one—each of which is controlled by a micrometer screw provided 
with a divided circle or drum, so that the width of each half of the slit may 
be ascertained by direct reading (see Fig. 26). In so-called symmetrical slits, 


a b 


c 


Frc. 26.—Double slit employed in Vierordt’s method of spectrophoto- 
metry, as adjusted to their spectrophotometers by the Brothers 
Kriiss of Hamburg. 


both edges of the slit move symmetrically. When the two halves of such a 
slit are of the same width, 77 the dlumination be uniform, the observer, on 
looking through the telescope of the spectroscope, observes two superposed 
spectra of equal brightness. If one slit be narrower than the other, the 
illumination of the corresponding spectrum will be diminished in proportion. 
The second modification which has to be made in the ordinary spectro- 
scope consists in substituting for the usual eyepiece, one which is provided 
with a slit for isolating any desired region of the spectrum, the remainder of the 
spectrum being concealed from view. In Vierordt’s original instrument this slit 
was formed by two lateral shutters, moving in the focal plane of the eyepiece, 
which could be approximated to any desired extent. This simple contrivance 
has been perfected by Hiifner, and adapted to his beautiful spectrophotometer. 
A very ingeniously contrived and readily adjusted slit has been devised by the 
Brothers Kriiss of Hamburg, and adapted to the spectrophotometers made by 


METHODS OF SPECTROPHOTOMETRY. 217 


their firm. Whatever the precise form of the slit in the eyepiece, it must 
permit of the isolation of a perfectly defined spectral region, and of the precise 
determination of the limits of that region, these being expressed in wave 
lengths.!_ For all coloured solutions there are regions in which the absorption 
of light is peculiarly distinctive, and which are specially favourable to the 
determination of the coefficient of extinction. In the case of oxyhemoglobin, 
Hiifner has in his most recent researches selected a part of the region 
between the two absorption-bands (A 550-A 540) and a part of the region 
lying within the second band (A 542°5-A 531°5). 

There remains to be described an absolutely essential accessory to the 
spectroscope, without which it would be impossible to determine the spectro- 
photometric constants. This is a specially contrived glass trough, for holding 
the solutions to be investigated, the anterior and posterior walls of which 
are formed by two perfectly parallel glass plates. Two forms of this trough 
are shown in Fig. 27, whilst Fig. 28 exhibits a trough mounted on_ its 


7 


Fie. 27.—Glass troughs for containing the liquids Fic. 28.—Trough mounted on stand, 
to be examined by the methods of spectro- as used in spectrophotometry.— 
photometry.—After Kriiss. After Kriiss. 


stand, the stand permitting of the trough being easily and gradually 
lowered or raised, and of its being accurately levelled. 

The inner surfaces of the parallel glass plates of the 

little trough are exactly 11 mm. apart. A glass 

cube (called after the person who suggested its use, 

der Schulzsche Glaskirper) exactly 10 mm. broad, 

and half the height of the interior of the trough, 

rests on the floor of the latter, so that the anterior 

and posterior surface of the cube shall be parallel a 

with the glass plates of the trough (Fig. 29). When 

the coefficient of extinction of a coloured liquid is 

to be determined, such a trough is filled with it. 

When light passes through the lower half of the frig. 29.—Section of glass 
trough, it must traverse a stratum of coloured liquid trough with the Schudz- 
1 mm. in thickness, whilst light passing through ‘se G@laskorper, a, in situ 
the upper half traverses a stratum 11 mm. thick. fechemstio) irs after Eris. 
In the latter case, the light is subjected to the absorbing action of a layer of 


1 The reader who wishes to understand the details which are necessary for practical 
work in spectrophotometry is advised to read in the first instance a useful, indeed almost 


218 HAMOGLOBIN. 


coloured liquid 1 em. broader than that which is contained in the lower half 
of the trough, and this is for spectrophotometric purposes exactly equivalent 
to interposing a stratum | cm. broad in the path of the light impinging on one 
(the upper) half of the slit, and no coloured liquid in the path of the light 
reaching the other half. 

Spectrophotometric measurements are invariably made by the aid of artificial 
light. Hitherto, oil or petroleum lamps have been used for this purpose, but 
lately Hufner has adopted a gas lamp fitted with an Auer incandescent burner. 

We are now in a position to complete our explanation of Vierordt’s 
method. We shall assume that a spectrophotometer, such as has been 
described, is at the disposal of the observer. The lamp is lighted and the 
height of the flame adjusted, so as to equally illuminate the two halves of the 
double slit; this is seen to be the case when with equal widths of the slits 
two superposed spectra of exactly equal brightness are seen. The two 
halves of the slit are then opened to the extent which is thought advisable ; 
we shall, for convenience of description, suppose that they have been opened 
to the extent represented by the index on the two divided circles of the 
micrometer screws, pointing to the division 100. The observer then arranges 
the slit in the eyepiece, so as to isolate and measure precisely the region of 
the spectrum for which he desires to determine the coefficient of extinction. 
In the case of hemoglobin, of oxyhemoglobin, and of CO-hemoglobin, he will 
select for his observations one of the two regions which have been shown by 
Hiifner to be specially favourable to the determination, and in which he has , 
determined the constants which he distinguishes as A, and A’, respectively. 


Fie. 30.—A_ spectrophotometer with absorption trough and lamp as 
arranged for spectrophotometric determinations by Vierordt’s 
method. 


This operation having been effected, he will again observe whether the two 
limited spectral areas appear to be of precisely equal brightness. If this is 
the case, the trough containing the coloured liquid is brought in front of the 
double slit, and the height of the former is carefully adjusted, so that the 
upper border of the glass cube appears as a line exactly coinciding with the 
separation between the upper and the lower spectral strips. 


indispensable, book by Dr. Gerhard Kriiss and Dr. Hugo Kriiss, entitled “‘ Kolorimetric 
und quantitative Spektralanalyse, etc.,” Hamburg u. Leipzig, 1891. Though specially 
written for those who intend to work with Hiifner’s instrument, an accurate though very 
succinet account of spectrophotometry is contained in a pamphlet entitled ‘‘ Anleitung 
zum Gebrauche des Hiifner’schen Spectrophotometers, ete.,” von Eugen Albrecht, Univer- 
sitits-Mechaniker in Tiibingen: Tiibingen, 1892. Subsequently, all Hiifner’s papers on 
spectrophotometry should be studied. 


METHODS OF SPECTROPHOTOMETRY. 219 


We shall suppose this result to have been attained, and next direct our atten- 
tion to the relative illumination of the two spectral areas under examination. 
It will be at once seen that the interposition of the absorption-cell has brought 
about a great difference in this respect. The upper spectrum is seen to be 
much less bright than the lower, the difference depending upon the amount 
of colouring matter in solution. Unless the concentration be excessive, we can 
restore the equality of illumination of the two superposed spectral areas by 
narrowing the lower slit. This is done with great care until we are convinced 
that the luminous intensity is the same in both, or that we have secured the 
greatest attainable equality (see, below, the discussion of the objections to 
Vierordt’s method). We have then merely to read the division on the 
divided circle of the micrometer screw of the lower half of the slit. Supposing 
we find that the width of the lower slit is represented by division 20, whilst 
the width of the upper slit remains at 100, then the former number represents 
the percentage of unabsorbed light. We have seen that the extinction- 
coefficient « can be determined by the formula— 


' e= —log J’, where I’ 


represents the unabsorbed light. By a table of logarithms, or more quickly by 
special tables, we find that in our case— 
e= — log {%, =log 100 —log 20 


e=0°69897 


As has been shown, having determined ¢«, we may, if we know the precise 
proportion of colouring matter contained in the coloured solution, calculate the 
value of A; or supposing that the substance is one of which the value of A 
has been determined, and that we are unacquainted with its concentration, we 
ean ascertain the latter by the formula c= Ae. 

Although Vierordt’s method of determining the extinction-coefficient 
possesses historical interest, and its study is the natural introduction to that 
of the more perfect methods which have been suggested by it, it is open to 
serious objections, to the principal of which reference may here be made. 

However wide one slit may be, and however much the other may be 
narrowed, it is, in the case of solutions of high colorific intensity, most difficult, 
or impossible, to obtain by these means alone equality in the illumination 
of the spectra ; and accordingly Vierordt frequently had recourse to the use of 
smoke-tinted glass plates (Rauchglaser) of previously determined absorptive 
power, these being interposed in the path of the light which had not traversed 
the coloured solution. There are unquestionably theoretical and_ practical 
objections to this mode of proceeding. The principal objection to Vierordt’s 
method is, however, a fundamental one, namely, that no absolute comparison 
is possible between spectra obtained with slits varying considerably in width. 
The more the slit of a spectroscope is widened, not only does the amount of 
light admitted increase and the spectrum become brighter, but the more and 
more impure does it become, 7.¢. the greater the admixture of light of different 
wave lengths in any region of the spectrum. But the accurate determination 
of the coefficient ¢ is only possible with monochromatic light. It has been 
sought to diminish the error due to the cause just referred to by substituting 
for the original double slit of Vierordt one of which both edges move symmet- 
rically, so that the centre of the slit remains in a constant position. Although, 
doubtless, the error is reduced in this way, it is not entirely corrected. 

Although Vierordt’s method of determining the value of the co-efficient « 
will probably fall in future into disuse, his great merit of having been the 
first to work out a method of spectrophotometry admitting of considerable 
accuracy, and of having discovered and established its applicability to the 
quantitative analysis of colouring matters, will always endure. 

Hiifner’s method.—This method, which has been made more and more 


220 HAMOGLOBIN. 


efficient by the long-continued labours of its author, differs from Vierordt’s in 
the mode by which the equalisation of the intensity of two beams of light is 
brought about, the difference in mode requiring a spectrophotometer which 
differs in important respects from the instrument already described. 

In Hiifner’s spectrophotometer there is a single slit, the width of which, 
after it has been once adjusted, is never varied. 

The light which reaches one-half of this slit has been polarised by a small 
Nichol’s prism (the polariser), whilst that which reaches the other half (which 
in the determination of the value of ¢ passes through the thicker stratum of 
coloured liquid) is unpolarised. When these two beams of light fall upon the 
refracting prism of the spectroscope, they are refracted and furnish two super- 
posed spectra, of which that corresponding to the polarised beam is naturally 
much less intense than the other. Before making any observations of «, the 
two spectra must be equalised, this being done by interposing a wedge of 
smoke-tinted glass in the path of the unpolarised beam. Equality of both 
spectra having been obtained, if a coloured medium be placed in the path of 
the unpolarised beam, its spectrum will be correspondingly reduced. Equality 
is, however, restored by rotating a second Nichol’s prism (the analyser) which 
is in the path of the beams issuing from the refracting prism, and the rotation 
of which diminishes the intensity of the polarised beam alone. When equality 
in the illumination of both spectra has been restored, the angle (#), through 
which the analysing Nichol has been rotated, is measured in two opposed 
quadrants of a divided circle provided with a vernier, and from the value of 
¢ that of J’ is calculated. 

If the original intensity of the light=1, and the intensity of the un- 
absorbed light which has traversed the coloured medium be represented by 
I’, then 


I'=cos*9¢ ; 
If the layer of coloured liquid investigated be always =1 (e.g. 1 em.), then 
as e= —log I’, 
«= — log cos*¢ 


The following example will illustrate the mode of procedure and the steps 
of the calculation in an actual experiment for the determination of the ex- 
tinction-coefficient of blood, carried out with Hiifner’s spectrophotometer :— 

1 c.c. of defibrinated blood of the ox was diluted to 160 c.c. with a 0-1 
per cent. aqueous solution of Na(OH). The absorption-trough was filled with 
some of the perfectly clear red liquid thus obtained. The spectral region (r), 
for which e was determined, was one of the two in which Hiifner has, in his 
most recent experiments, determined the constant A of oxyhzemoglobin (7.e. 
a portion of the region between the bands a and f of oxyhemoglobin). 

r =A557°5 — A568°7 
(Mean of ten measurements) @ =61°:8 
Converting the decimal 
fractions of a degree into 
seconds bibl ib2i 


It has been stated that with Hiifner’s spectrophotometer 


T= cost 
3 9 
and «= — log cos*p 
In the above experiment 
e= — log cos*61°52’ 


"= —2 log cos6 1°52’ 
“= —2 (0°67350 — 1) 
“= —1:34700+2 
"=0°653 


ore 


HUFNERS SPECTROPHOTOMETER. 221 


Hiifner’s spectrophotometer is an instrument of so much importance to the 
physiologist who intends to work at spectrophotometry, that a short descrip- 
tion of the arrangements of its several parts appears desirable. 

The instrument as a whole, as well as the stand carrying the absorption- 
trough and the lamp, are shown in Fig. 31. 


Fic. 31.—Hiifner’s spectrophotometer, as made by Albrecht. 


The spectrophotometer, the stand for the trough, and the lamp, rest upon 
the optical bench which forms the base for the whole. The position of the 
spectrophotometer is constant; the trough-stand and the lamp move along a 
slide, and can be placed at any required distance. During the actual experi- 
ment, the anterior edge of the trough is in close contact with the anterior part 
of the collimator. The lamp (which in the models recently and at present 
constructed is a gas lamp provided with an Auer incandescent burner) is 
for actual work placed at a distance of 24 to 25 cms. from the distal end of the 
collimator. The lamp is fitted with a positive lens the focus of which is 
made to correspond with the brightest part of the flame, so that perfectly 
parallel rays fall upon the absorption-trough. (The latter is in all respects 
similar to the one used in Vierordt’s method. 

Turning our attention to the spectrophotometer, see Fig. 31, it is seen to be 
composed of a three-footed stand, furnished with levelling screws, the stand 
supporting the platform on which is fixed the dispersing prism, which is 
enclosed in a metallic case. To the right is seen the collimator and to the left 
the telescope. 

1. The collimator.—This is furnished with a single slit formed by the 
edges of two slides moving transversely, each of which possesses its own 
micrometer screw, furnished with an accurately divided drum. This arrange- 
ment enables a slit of a precisely known width to be obtained, and the slit can 
be widened or narrowed symmetrically,—so that its centre remains constant. 

Unlike ordinary spectroscopes, Hiifner’s spectrophotometer has, fixed to the 


4 


222 HAMOGLOBIN. 


front of the slit, a metallic box enclosing the following optical parts. (In order 
to facilitate our description, these are shown in the following diagram, Fig. 32, 


Fic. 32.—Schematic representation of the path followed by the rays of 
light before entering the slit of the collimator of Hiifner’s spectro- 
photometer.—After Kriiss. 


which indicates also the path of the rays passing through the glass trough 
containing the coloured solution.) 

Placed centrally, in the position shown in the diagram, is an oblique parallel- 
opiped of flint glass, with two of its diagonally-opposed angles in a line with 
the optic axis of the collimator. This admirable optical contrivance (which 
is known in Germany after the optician who devised it as “der Albrecht’sche 
Glaswiirfel oder Glaskérper”) refracts light falling on its two anterior faces 
so as to alter its direction, as shown in the diagram, and as will be after- 
wards referred to. Placed anteriorly to the lower half of Albrecht’s body 
is the small Nichol’s prism d. Corresponding to the upper part of the glass 
body is a composite glass plate e, with perfectly parallel sides. This plate is 
formed by cementing together two glass wedges, of which one is of clear glass 
and the other of smoke-tinted glass, and can be moved from side to side by 
means of a special arrangement. According to the position of this plate it 
will absorb more or less light. The purposes of these various parts are 
sufficiently obvious from the diagram ; aa represents the absorption-trough for 
containing the coloured liquid to be spectrophotometrically investigated. In 
the lower half of the trough is seen the Schulz’s cube (>); 7 and 7’ represent 
two parallel beams of light falling on the anterior surface of the trough. The 
lower beam (7) traverses in its path the Nichol prism (//), and is polarised ; 
falling then on the adjacent surface of the parallelopiped, it is deviated so 
as to fall upon the upper half of the slit. The upper beam may or may not 
meet in its path the composite plate ¢ previously referred to, and to which 
reference will again be made. This beam is so deviated as to fall upon the 
lower half of the slit. After traversing the structures just described, two 
beams of light fall upon the slit—a polarised beam on the upper haif and a 
non-polarised beam on the lower. 

2. The telescope.—A very ingenious arrangement, which is indicated by 
a separate drawing in the centre of Fig. 31, permits of the precise 
position of the telescope in reference to the prism being determined, and 
consequently of the most accurate determination of the position of any line 
in the spectrum. The reader is referred for details to Professor Hiifner’s 
original description. At the distal end of the telescope is the object glass, 
next to it isa Nichol’s prism, the rotation of which is measured on a graduated 
circle by the help of a vernier. In the focal plane of the eyepiece is a 
modification of Vierordt’s eyepiece slit, permitting of any determined spectral 
region being exactly isolated. For further details as to the construction and 
adjustment of the spectrophotometer, the reader is referred to the original 


SPECTROPHOTOMETRIC CONSTANTS. 223 


sources of information. It is absolutely essential to work with Hiufner’s 
spectrophotometer in a perfectly darkened room. 

Before commencing photometric measurements, the observer will ascertain 
whether the analysing Nichol is in the position in which it allows the polarised 
beam to pass unabsorbed. He will then fill the absorption-trough, and isolate 
and measure the spectral region for which the extinction-coefficient is to 
be determined. 

On now looking through the eyepiece two spectral strips will be seen, 
separated by a sharp horizontal line ; these spectral strips will be of unequal 
brightness ; the upper, being a portion of the spectrum of the polarised 
beam, will be much less luminous than the lower. The composite glass 
plate in front of the slit of the collimator is now moved inwards in the 
direction of the beam of the unpolarised light, so as to diminish its intensity, 
until the upper and the lower spectral strips appear of precisely the same 
brightness. 

The trough containing the coloured liquid under investigation is now 
brought into position, the upper surface of the glass cube in the trough being 
placed about 1 mm. below the plane passing through two horizontal angles of 
Albrecht’s glass body. On now examining the spectra, it is at once seen that 
the lower of the two is darker than the upper. The analysing Nichol is then 
carefully rotated until equality in the intensity of the two spectral strips is 
attained ; the angle through which the prism has been moved is then deter- 
mined ; several, say five, sets of readings being made in two opposite quadrants 
of the large divided circle. The mean of these readings gives the value 


of ¢.! 


The spectrophotometric constants of oxyhemoglobin.—It was 
previously stated that it is usual to determine the photometric constants 
of colouring matters in two spectral regions, those regions being chosen 
in which the variations in the absorption of light are most rapidly affected 
by variations in the concentration of the colouring matter. 

The reasons for determining in the first instance at least two values 
for A (which we shall distinguish as A and 4’), and subsequently, each 
time that a determination is made, ascertaining the value of « in the 
same two regions (the two extinction-coefficients being distinguished 
as « and «, or in the case of oxyhemoglobin as «, and «,’) are the 
following :—(1) If we know the value of A and A’ for any body, we are 
able to make two independent estimations when determining the 
concentration of a solution of the same body of unknown strength, the 
one estimate acting as a check on the other. (2) The knowledge of the 
value of A and 4d’, for each of two colourmg matters co-existing in 
solution, is a necessary condition to being able to determine spectro- 
photometrically the amount of each constituent when occurring together. 
(3) In the case of oxyhemoglobin, hemoglobin, and CO- -heemoglobin, the 

’ 


A (ae Sts c 
quotient — is absolutely characteristic of each substance, and affords a 
= 


valuable check on the purity of the colouring matter in solution and on 
the accuracy of the analysis. 

Hiifner’s most recent determinations? of the spectrophotometric 
constants of oxyhemoglobin, made with his perfected spectrophotometer, 
have led to the results shown below. The two values of 4 are, as has 


1 Hiifner’s spectrophotometer is constructed by, and can be obtained from, the original 
maker, Herr Eugen Albrecht, Universitats-Mechaniker in Tubingen. 

2 Hiifner, ‘<Photometrische Constanten des Oxyhimoglobins,” Arch. f. Physiol., Leipzig, 
1894, Physiol. Abth., S. 134 et seq. 


224 HAEMOGLOBIN. 


been previously stated, in the case of oxyhemoglobin, distinguished by 
the symbols A, and 4',; the first has been determined for the spectral 
region which les between the two bands @ and § of oxyhemoglobin, 
and is limited by ~ 554 and ~ 565; the second has been determinéd for 
the spectral region which corresponds to the darkest part of the second 
(8) band of oxyhzemoglobin, and extends from % 531°5-2 542°. 


Spectrophotometric Constants of Oxyhemoglobin! (Hiifner). 


| 


| Limits of Spectral Region in which Absorption relation 4, and A’, corre- 

| é) and <’, were determined. | sponding to the two regions. 

[CR ofer) ow. NSE SCH |S ee ae 
(Rote) . ADS15-N542°5 1 | A ee 


| | 


From the above constants we are able, as has been shown (see p. 215), 
to determine the percentage of hemoglobin in the blood with surprising 
accuracy. The further use of these constants will be referred to in 
explaining the mode of determining the relative amounts of hemoglobin 
and oxyhemoglobin coexisting in any sample of blood. 

We have now to consider in some detail the light which spectro- 
photometry has shed on certain questions which possess great interest 
to the physiologist, and which have up to a certain point been already 
discussed in this article. 

Hiifner and his pupil v. Noorden long ago noticed that the quotient 

, id 
Ee which is the same as —%, was remarkably constant, not only in 


b 


0 0 
the blood of animals of the same species, but in all, however widely 
separated in the animal scale.? Subsequent researches by Hiifner and 
his pupils, carried out with a much more perfect spectrophotometer 
than the one employed by v. Noorden and himself, more than confirm 
the earlier results in so far as the constancy of the quotient is 
concerned. 

If the defibrinated blood of any animal, diluted with 150-160 parts 
of 0-1 solution of NaOH, or a solution in the same dilute NaOH of 
erystals of oxyhzemoglobin of approximately equivalent concentration, 
be thoroughly oxygenated by shaking with air and the values of ¢ and 
e, be determined, it will be found that the quotient > will vary very 

0 
slightly from 1°580. In very few determinations, out of a large number, 
was it as low as 1°578. So soon, bowever, as the blood commences to 
undergo any change, as, ey., a partial conversion into methemoglobin, 
the coefficient is lowered. 


1The values of 4, and A’, given above differ materially from those which had been 
assigned to them previously by Hiifner and his pupil v. Noorden as a result of researches 
carried out with Hiifner’s earlier and much less perfect spectrophotometer, and employing 
hemoglobin which had been frequently recrystallised. 

2 y, Noorden’s observations included the blood of man, the dog, the cat, the rat, the 
guinea-pig, and the owl. ‘‘Beitrige zur quantitativen Spektralanalyse, in besondere zu 
derjenigen des Blutes”’ (aus d. Lab. d. Prof. Hiifner in Tiibingen), Ztsehr. 7. physiol. Chem., 
Strassburg, 1880, Bd. iv. S. 9-35. 


THE PHOTOGRAPHIC SPECTRUM. 225 


From the extraordinary constancy of this quotient some interesting 
conclusions may be legitimately drawn. (1) The constancy of the 
quotient in all animals affords presumptive evidence, amounting to 
absolute proof, that the iron-containing molecular group existing in 
hemoglobin, upon which its colour, its light-absorbing power, and its 
capacity to combine with O, CO, and NO depend, is identical in 
all animals. The truth of this hypothesis is borne out by many 
weighty facts, eg. the identity in chemical composition (as revealed 
by analysis) of the iron-containing products of the decomposition 
of hemoglobin, whatever its source; the constancy in the propor- 
tion of O and CO which can combine with 1 grm. of hemoglobin 
of different animals. (2) The constancy of the quotient (whether 
solution of crystallised hemoglobin, or an alkaline solution made by 
diluting defibrinated blood with 0:1 per cent. vol. of Na(OH), or a 
liquid holding intact blood corpuscles in suspension, be investigated), 
shuts out the possibility of more than one colouring matter existing 
in the blood. It renders absolutely untenable the views of Bohr, 
who has assumed the existence of several hemoglobins, possessed 
of different powers of combining with oxygen; and utterly disproves 
Hoppe-Seyler’s hypothesis that the colouring matter of the corpuscles 
is distinct from hzemoglobin so as to deserve a special designation of 
arterin or phlebin, as the case may be. 


(b) The photographic spectrum.—In the year 1878 the late 
Professor J. L. Soret, of Geneva, in his first memoir on the absorption 
of the ultra-violet rays of the spectrum by diverse organic substances,} 
announced the fact that diluted blood, when examined with the aid 
of a spectroscope provided with a fluorescent eyepiece, presented in 
the extreme violet, between Frauenhofer’s lines G and H, an absorp- 
tion-band which appeared to him to be slightly shifted towards the 
less refrangible end of the spectrum, when the blood solution was 
saturated with carbonic oxide. Soret subsequently? confirmed the 
accuracy of the above facts, employing the photographic method in 
his experiments, though he published none of his photographs. Since 
the date of the publication of Soret’s short notes on this subject, 
d’Arsonval® has independently, and without referring to Soret’s observa- 
tions, described anew the extreme violet absorption-band of the blood- 
colouring matter, but without adding to the facts discovered by the 
Swiss observer. 

The complete absence of all reference to Soret’s scanty but 
interesting and suggestive observations, in text-books and _ treatises 
on physiology and physiological chemistry; and the fact, which my 
own observations soon elicited, that the absorption-band of Soret is 
even more distinctive of the blood-colourmg matter than the absorp- 
tion-bands in the visible spectrum which have hitherto engrossed the 
attention of observers, led me to study this absorption-band in more 
detail in hemoglobin, its compounds and principal derivatives.t I 


1J. L. Soret, ‘‘ Recherches sur l’absorption des rayons ultra-violets par diverses 
substances,” Arch. d. sc. phys. et nat., Geneve, 1878, pp. 822, 359. 

2 Soret, cbid., 1883, pp. 194, 195, 204. 

3 A. d’Arsonval, Arch. de physiol. norm. et path., Paris, 1890, Sér. 5, tome ii. pp. 340-346. 

4A. Gamgee, ‘‘On the Absorption of the Extreme Violet and Ultra-Violet Rays of the 
Solar Spectrum by Hemoglobin, its Compounds, and certain of its Derivatives,” 
Proc. Roy. Soc. London, 1896, vol. lix. p. 276. 


VOL. I.—I5 


226 HAEMOGLOBIN 


propose that the band in the extreme violet should henceforward be 
distinguished as the band y, or the band of Soret, in the spectrum of 
oxyheemoglobin. 

Methods of demonstrating the band of Soret.—The limits of visibility 
of the solar spectrum correspond, as usually stated, with the H group of 
lines; here lies the arbitrary boundary which separates the extreme 
violet from the ultra-violet properly so called—that region which 
we can only see by interposing fluorescent media in the path of the 
rays (eg. a fluorescent eyepiece), or by allowing the spectrum to fall 
on a fluorescent surface—the region which is best studied by the aid of 
photography. 

Although Soret’s band lies at the limit, but yet within the boundaries, 
of the visible spectrum, it is impossible to see it with the ordinary 
spectroscope, 7.e., unless this be provided with special devices. It has 
already been stated that it can be seen with any spectroscope, if we 
substitute a fluorescent for the ordinary -eyepiece; a cell contaiming 
a dilute solution of esculin must, however, be substituted for and 
placed in the position of the uranium glass plate of the eyepiece, 
uranium glass fluorescing most feebly in the light of the spectral region 
where the absorption-band under discussion is situated. It was, indeed, 
with the aid of his fluorescent eyepiece that Soret first discovered this 
band, though d’Arsonval asserts that it 1s impossible to see it in this 
way. Observations with the fluorescent eyepiece are, however, difficult 
-and require experience. Still more difficult and unsatisfactory is the 
method, also suggested by Soret, and lately published as an original 
suggestion by d’Arsonval, of rendering this band visible by interposing a 
blue glass between the eye and the spectroscope. If the lght be very 
intense the band is just perceptible to a person who is already 
acquainted with its position and characters through other methods of 
observation. 

In order to demonstrate Soret’s band and the absorption-bands in 
the ultra-violet of derivatives of the blood-colouring matter, I projected 
the spectrum of sunlight or of the positive pole of the electric are on to 
a fluorescent screen, similar to those which have since come into 
common use in observations made with the X or Rontgen rays, 
i.e. a screen made by coating a white surface, such as cardboard, with 
barium platimocyanide. 

In order to render absorption- bands of coloured liquids in the 
extreme violet and ultra-violet beautifully visible by this method, it is 
essential, however, to open the slit which intervenes between the 
source of light and the collimating lens very widely. In the highly 
luminous spectra thus obtained, though none of the spectral lines 
are visible, except perhaps H and K appearing blurred and indistinct, 
absorption-bands appear with remarkable distimctness and sharpness. 
The method is valuable, not only for purposes of demonstration, but 
for making preliminary observations prior to having recourse to 
photography. By its help I ascertained with correctness the position 
and characters of the extreme violet and ultra-violet absorption-bands 
of the acid compounds of hematin, of methemoglobin, of hemato- 
porphyrin, and of turacin. In no case where this method yielded 
negative results, was the presence of a band afterwards demonstrated 
by photography. 

As few physiological laboratories possess a perfectly darkened optical 


SOLAR 


Sprecrrum, 


H®MOGLOBIN. 


O,-TLMOGLOBIN, 


THE PHOTOGRAPHIC SPECTRUM. B29 


room provided with a heliostat for projecting a beam of sunlight into it, 
the following simple arrangement,! which requires merely an electric 
are lamp and an ordinary laboratory spectroscope of the Bunsen type, 
may be adopted.2 The telescope of the spectroscope is removed, and 
a beam from the + pole of the are is allowed to fall on the slit of the 
collimator. The spectrum is focussed on a fluorescent screen, then the 
slit is opened very widely. If the spectrum be a continuous one 
(which is the case if it be that of the positive pole of the electric 
arc), the coloured solution is then interposed in the path of the beam 
falling on the slit. 

The position and limits of Soret’s band—LDefibrinated arterialised 
blood, diluted with from 400 to 600 volumes of distilled water, or still 
better with a similar amount of 0-1 per cent. solution of sodium hydrate, 


G h HK L M N 


Fia, 33.—The photographic spectrum of hemoglobin and oxyhemoglobin, 


furnishes solutions (containing about 1 part of oxyhzmoglobin in 3000 
and 1 part in 5000 respectively) of a concentration suited for 
photographic investigations of the spectrum. With solutions of this 
strength (a stratum 1 cm. thick being placed in the path of the beam 
falling upon the slit of the collimator) Soret’s band can be studied 
to perfection, though it can be well seen with solutions much more 
concentrated and much more dilute. The appearance and position of 
Soret’s band in the spectrum of oxyhemoglobin are shown in Fig. 33 
along with that of reduced hemoglobin. 

Within fairly wide limits of “concentration (the stratum examined 
being invariably 1 cm. wide), the limits and characters of Soret’s band 


1] employed this simple arrangement in demonstrating these bands in the violet and 
ultra-violet to members of the Internat. Physiological Congress, Bern Meeting, September 
1895. 

? Direct vision spectroscopes cannot be used, the absorption of the ultra-violet rays being 
very great in these instruments. 


228 HAEMOGLOBIN. 


remain very constant, the increase in the amount of oxyhemoglobin 
influencing more the intensity of the band than its width. In the case 
of solutions containing approximately the proportion of oxyhemoglobin 
above mentioned (ze. from 0°20 to 0°33 parts in 1000), ‘the spectral 
region between F and G is absolutely unshaded. Soret’s band is then 
seen, extending from ~ 404-2 454; ze. it occupies the greater part of the 
spectral region intervening between G and H; the edges, however, 
uniformly shade away as far as these lines. 

By examining a series of photographs of spectra obtained by inter- 
posing solutions of oxyhemoglobin of very different concentrations, I 
have determined that the mean ray absorbed does not, as Soret thought, 
coincide with h (4 410-1), but is decidedly on the red side of that line, 
corresponding to ~ 414. 

When the concentration of the solution of oxyhzemoglobin increases, 
the width of the band very slowly increases. Its less refrangible border 
never passes beyond G; as the solution becomes highly concentrated, 
the band widens perceptibly, and it does so in the direction of the ultra- 
violet. With a solution made by diluting 1 volume of blood to the volume 
of 250 (water or 0-1 per cent. solution of Na(OH) being employed as the 
diluent), the absorption-band, though much more intense than with the 
more dilute solutions, retains almost the same boundaries, its shadowy 
borders approaching, but not passing beyond, G and H. With a 
solution containing 1 part of blood in 100, the appearances differ 
remarkably from those previously referred to. The solution is 
transparent for lhght from F to nearly G; it transmits light with 
difficulty from L to N (4 381-°9-2 350-01); the remainder of the ultra- 
violet is completely absorbed. A solution containing 5 per cent. of 
defibrinated blood (or about 6°5 parts of oxyhemoglobin in 1000 parts) 
absorbs the whole of the violet and ultra-violet regions of the spectrum, 
with the exception of a region between F and G, but nearer the former 
(~ 460-2 490). 

It remains to be considered with how dilute a solution of oxy- 
hemoglobin a photographic record of Soret’s band can be obtained. 
Examining a stratum 10 mm. broad I have obtained definite results, 
when the solution contained somewhat, but not much, less than 1 part 
of oxyhemoglobin in 10,000. 

No colouring matter yet investigated exhibits the intense absorption- 
band between G and H which is characteristic of hemoglobin and its 
compounds. Several substances (carmine, picro-carmine, and the colouring 
matter of alkanet root) exhibit absorption-bands in the visible part of 
the spectrum which bear a superficial resemblance to those of oxy- 
hemoglobin. The spectrum of none of these colouring matters exhibits, 
however, any absorption in the extreme violet or the adjacent ultra- 
violet. 

The researches which I have conducted have shown that the band of 
Soret depends on the iron-containing group existing in the hemoglobin 
molecule, yet not upon its iron. The variations in character and position 
which this band exhibits in the various compounds and derivatives of 
hemoglobin will be referred to under each. 


———— 


HEMOGLOBIN (REDUCED H4#MOGLOBIN). 229 


HaMoGLopin (REDUCED HaiMOGLOBIN). 
SynonyM, “PURPLE CRUORIN.” 


Historical note.—Fully two years had passed since the date of Hoppe’s 
publication (1862) of his observations on the spectrum of blood, before it was 
shown that the oxygen which enters into combination with hemoglobin has 
a fundamental influence on its spectrum. It was on the 16th of June 1864 
that Professor Stokes! communicated to the Royal Society the mteresting 
observation that when diluted blood is treated with certain reducing agents, 
the colour of the liquid and its spectrum undergo remarkable changes ; the 
former loses its bright red appearance, becoming darker in tint, whilst the 
absorption-bands a and £ are replaced by a single band which we may 
designate the band y, which appears less deeply shaded and with less defined 
edges, and which extends from D nearly to E. If, now, the solution which 
exhibits this spectrum be shaken with air or oxygen, the single band at 
once gives place to the two original bands, whilst the liquid reacquires 
more or less of its primitive florid-red colour. The process of reduction 
and oxidation may be repeated many times in succession. 

From his experiments, Stokes concluded that “the colouring matter of blood, 
like indigo, is capable of existing in two states of oxidation, distinguishable by a 
difference of colour and a fundamental difference in the action on the spectrum. 
It may be made to pass from the more to the less oxidised state by the action of 
suitable reducing agents, and recovers its oxygen by absorption from the air.” * 

The researches of Magnus, Lothar Meyer, and Claude Bernard had shown 
that the blood holds in solution an amount of oxygen greatly in excess of that 
which could exist in a state of simple solution, but that this oxygen exists ina 
condition which permits of its being extracted from the blood by boiling in a 
Toricellian vacuum, as well as by the action of carbonic oxide. Hoppe-Seyler, 
having succeeded in crystallising oxyhemoglobin, and, by means of its optical 
properties, having identified it with the colouring matter as it exists in the living 
blood, was able to show that a solution of crystallised oxyhemoglobin behaves 
towards reducing solutions in the same manner as diluted blood; that, like blood, 
it yields oxygen when boiled in vacwo, and that the blood-colouring matter thus 
deprived in vacuo of its loosely combined or respiratory oxygen manifests the 
absorption-band which had been described by Stokes as the result of reduction. 

The further steps in the growth of our knowledge of reduced hemoglobin 
will be more conveniently referred to in discussing the chief facts with which 
we are acquainted relative to this remarkable body. 


Methods of effecting the reduction of oxyhemoglobin to reduced 
hzemoglobin.—In nearly all experiments on the reduction of oxyhemo- 
globin, diluted blood may be substituted for a solution of the pure blood- 
colouring matter, it having been shown by the spectrophotometric and 
chemical researches of Hiifner that, both in respect of their power of 
absorbing light and of the influence of reducing agencies upon them, the 
two solutions possess identical properties. Instead, however, of employ- 
ing pure distilled water as a diluent, it is advisable to use, according to 
Hiifner’s plan, a 0-1 per cent. solution of sodium hydrate. A diluted 
solution of blood prepared in this way is free from all turbidity, and 
therefore more transparent than a pure aqueous solution, and undergoes 
putrefactive alterations more slowly. 


1“ On the Reduction and Oxidation of the Colouring Matter of the Blood,” Proc. Roy. 
Soc. London, 1864, vol. xiii. pp. 353-364 ; London, Edinburgh, and Dublin Phil. Mag., 
London, 1864, vol. xxviii. pp. 391-400. 

2 Stokes, op. cit., p. 357, par. 8. 


230 HAMOGLOBIN. 


1. By the action of reagents exerting a reducing action.— 
It is an essential condition which all reagents to be employed in the 
reduction of oxyhemoglobin to hemoglobin must fulfil, that they do not 
act destructively on these substances, as is the case with acids and salts 
possessed of an acid reaction. 

Ordinary solutions of ferrous sulphate or stannous chloride cannot, 
for instance, be employed, as they instantly lead to a decomposition 
of the blood-colouring matter. The first and still the most generally 
employed reducing agents, the use of which dates back to the researches 
of Stokes on the blood-colouring matter, are ferrous and stannous salts 
and the alkaline sulphides. Utilising the well-known property of citric 
and tartaric acids to prevent the precipitation of the salts of iron and 
tin by ammonia and the alkaline hydrates, Stokes indicated easy 
methods of preparing active solutions of ferrous and stannous salts for 
the study of the reduction of oxyhemoglobin. 

(a) Alkaline solutions of ferrous salts (Stokes’ reagent).—To a solution 
of a ferrous salt (usually ferrous sulphate or ferrous ammonium sulphate) 
(Fe(NH,),(SO,),.6H,O,), citric or tartaric acids or one of their alkaline 
salts is added, and then ammonia, until the reaction is alkaline. A light 
green solution is thus obtained, which rapidly darkens in the presence of 
air by the absorption of atmospheric oxygen. Such a solution, which 
must be freshly prepared, exerts a powerful and exceedingly rapid 
reducing action on oxyhemoglobin, even in the cold. Alkaline ferrous 
solutions possess the disadvantage, in proportion as they absorb oxygen 
and become oxidised, of becoming coloured, and absorbing the more 
refrangible rays of the spectrum, interfering, therefore, with the accurate 
study of the specific absorption due to the colouring matter. 

(b) Alkaline solutions of stannous salts.—These are made as described 
under a, by substituting a stannous (usually SnCl,) for a ferrous salt. 
As they do not become coloured on salt being oxidised, these solutions 
do not interfere with the accurate study of the absorption of the violet 
rays. Like the analogous ferrous solutions, those containing tin rapidly 
reduce hemoglobin even in the cold. 

(c) Solutions of the alkaline sulphides—Solutions of these salts 
(ammonium sulphide being almost invariably employed) effect the 
reduction of oxyhemoglobin, but much more slowly than is the case 
with @ and d, and their action is greatly accelerated by heat. Solutions 
of ammonium sulphide for this purpose should be freshly prepared, and 
be protected from the action of atmospheric oxygen and light, which 
bring about chemical changes, and cause them to assume a yellow colour 
and to absorb the violet end of the solar spectrum. 


Solutions of the crystalline sodium monosulphide (Na,S) cannot be 
employed with advantage as reducing agents for oxyhemoglobin, as, according 
to my experiments, they lead at once to the formation of sulphomethemo- 
globin, so that the pure spectrum of reduced hemoglobin cannot be observed. 


(f) Agitation with finely-divided iron, or with metallic iron reduced 
by hydrogen—the so-called officinal ferrum redactum2 7 


1 Rollett, ‘‘ Versuche ueber thatsiichliche und vermeintliche Beziehungen d. Blutsauer- 
stoffes,” Sitzwngsb. d. k. Akad. d. Wissensch., Wien, 1866, Bd. lii. Abth. 2, S. 246 et seq. 

* Ludwig und Schmidt, ‘‘Das Verhalten der Gase welche mit dem Blut durch den 
reizbaren Saugethiermuskel strémen,” Sitzungsb. d. k. Séichs. Gesellsch., Leipzig, 1868, Bd. 
xx. S. 12-72. 


HEMOGLOBIN (REDUCED H4MOGLOBIN). 231 


(9) Solution of sodium hydrosulphite (NaHSO,).—By the action of metallic 
zinc on a solution of sodium sulphate, in the absence of oxygen, a solution of 
intense reducing power is retained. Such a solution, which instantly decolor- 
ises indigo and litmus, reduces oxyhemoglobin.! 

Methods of determining the percentage of hemoglobin have been based on 
this reaction,” * though they have been abandoned as unreliable.4 

(h) Solution of hydrazin and its salts —It was pointed out by Curtius® that 
a solution of a salt of hydrazin reduces solutions of oxyhemoglobin with great 
rapidity ; and Hiifner® afterwards employed an aqueous solution of hydrazin 
hydrate to effect the reduction of concentrated solutions of oxyhemoglobin, 
the advantages of this reducing agent being that the only products of its 
decomposition are nitrogen and water, as shown in the following equation :— 

H,N—NH.,.H,0 + 0,=N,+3H,0. 
(hydrazin hydrate) 

2. By taking advantage of the reducing action exerted by pro- 
ducts of putrefaction.—The solutions of oxyhemoglobin, or of diluted 
blood, is set aside in sealed tubes, when, especially at temperatures ap- 
proaching 40° C., reduction rapidly occurs. It is worthy of remark that, 
whilst oxyhzemoglobin or its solutions very rapidly undergo change at 
temperatures above 0° C., such is not the case with reduced hemoglobin, 
which may be kept for many years in sealed tubes in the presence of 
putrefactive bacteria and the products of their activity. On opening the 
tubes and agitating with air, oxyhemoglobin is at once formed, and under 
favourable conditions may be crystallised. 

0. By taking advantage of the conditions which favour the 
“dissociation” of the compound of O, with hemoglobin.—(a) By 
boiling in a “Toricellian” or barometric vacuum; (b) by subjecting 
diluted blood or a solution of oxyhemoglobin to the action of a 
long-continued stream of a neutral gas, such as hydrogen, nitrogen, or 
nitrous acid. 

4. By temporarily arresting the circulation through a suffi- 
ciently transparent part of the animal body.—It was first pointed 
out by Vierordt,’ that the spectrum of oxyhzemoglobin can be satisfac- 
torily demonstrated by bringing two fingers (preferably the fourth and 
fifth) close together and passmg a beam of sunlight through the com- 
paratively thin layer of tissues at the boundaries of the adjacent fingers. 
He further pointed out that, on placing caoutchouc rings at the base of 
the first phalanges, after an interval varying between 40 and 300 
seconds (?), the two bands of oxyhemoglobin became replaced by the 
single band indicative of reduced heemoglobin.® 


«ep 


1 Schiitzenberger and Risler, ‘‘ Recherches sur le pouvoir oxydant du sang,” Compt. rend. 
Acad. d. sc., Paris, 1873, tome lxxvi. pp. 440-442, and pp. 1214-1216. 

2 Rollett, Zoc. cit. 

3 Ludwig and Schmidt, Joc. cit. 

4 Quinquand, ‘‘Sur un procédé de dosage de ’hémoglobine dans le sang,” Compt. rend. 
Acad. d. sc., Paris, 1877, tome Ixxvi. p. 1489. 

> Journ. f. prakt. Chem., Leipzig, 1889, Bd. xxxix. S. 27. 

§ ** Bestimmung d. Sauerstoffscapacitiit d. Blutfarbstoffs,” S. 156. 

7 «Das Himoglobinspectrum am lebenden Menschen,” Zéschr. f. Biol., Miinchen, 1876, 
Bd. xi. S. 188; and ‘‘ Die Sauerstoffzehrung der lebenden Gewebe,” ibid., 1878, Bd. xiv. 
S. 422. 

8 Refer to the following papers by A. Hénocque, ‘‘ Etude spectroscopique du sang a la 
surface sous-unguéale du pouce,” Compt. rend. Soc. de biol., Paris, Sér.. 8, tome i. p. 671; 
and also ‘‘ Notes complementaires,” zbid., p. 700. According to this author, the average 
time of reduction, when the circulation through the thumb is arrested, varies between fifty- 
five and sixty-five seconds. 


232 HAEMOGLOBIN. 


Preparation of crystallised hemoglobin (reduced heemoglobin).— 
It was shown almost simultaneously and independently by Kiihne! and 
by Rollett ? that highly concentrated solutions of pure oxyhemoglobin 
may, after reduction, be made to crystallise, and that the ery stals of 
reduced hemoglobin, though differing in colour and spectroscopic char- 
acters from the oxygen compound, are essentially identical with it in 
erystallme form. Kiihne explained that the difficulty which is en- 
countered, when attempting to crystallise reduced hemoglobin, depends 
upon its very great solubility. 


Hoppe-Seyler was unable to crystallise reduced hemoglobin ;* and Hiifner* 
in 1880 published a note, in which he announced that he had succeeded in 
obtaining crystals of reduced hemoglobin, though he neither then nor after- 
wards referred to the much more complete account published by Kuhne fifteen 
years earlier. 


In order to obtain crystals of reduced hemoglobin for microscopie 
examination, a pure and highly concentrated solution of oxyhemoglobin 
in very dilute ammonia is placed in a gas chamber, and a stream of 
chemically pure and thoroughly dried hydrogen is passed over it; as the 
solution evaporates cry stals separate. 

Nencki and Sieber have obtained large quantities of crystals of 
reduced hemoglobin by reducing concentrated solutions of pure oxyhe- 
moglobin of the horse through the agency of putrefactive bacteria, then 
adding a sufficient quantity of 25 per cent. alcohol and exposing to cold. 
The method which I employed more than twenty years ago, and which 
appears to me to offer some advantages, is to place a magna of pure 
oxyhemoglobin crystals with a small quantity of the mother liquor 
from which they have separated in a glass tube, so as nearly to fill the 
latter, and then to seal it. The tube is heated for some days in an 
incubator at about 35° C., and is then set aside in a cool place. After 
some weeks of exposure to a winter temperature, the tube is found to 
contain large quantities of crystallised and’ perfectly reduced hemo- 
globin. 

No one has hitherto attempted to recrystallise reduced hemoglobin, 
though, with the conveniences at present at the disposal of the scientific 
chemist, the process would present little difficulty. 

Characters of the crystals of reduced hemoglobin.—In form 
they are, as has been said, essentially identical with those of the 
oxygen compound, and like these are doubly refracting. Hiifner 
often obtained crystals 1 mm. long; and Nencki and Sieber, working 
with horses’ blood, obtained crystals, mostly in the form of hexagonal 
plates, 2 or 3 mm. in diameter. They are pleochromatic, appearing 
of a dark red colour in some lights, and exhibiting a bluish or purple 
tinge in others. 


1 “Das Vorkommen und die Ausscheidung des Himoglobins aus dem Blute,” Virchow’s 
Archiv, 1865, Bd. xxxiv. S. 423-436. 

2 Loc. cit. 

& { Med. Chem. Untersuch., Berlin, S. 378. 

**Ueber krystallische Himoglobin, ” Ztschr. f. physiol. Chem., Strassburg, 1880, 

S. oe It is singular that Nencki and Sieber, in an interesting and really valuable 
paper, should in 1887 have published again, as a new discovery, the obtaining of crystals 
of reduced hemoglobin, though they subsequently disclaimed all priority (see M. Nencki 
and N. Sieber, ‘‘ ‘Venise Hamoglobinkrystalle,” Ber. d. deutsch. chem. Gesellsch., Berlin, 
1886, Bd. xix. S. 128 and 410). 

= Kiihne, op. cit. 


COLOUR OF REDUCED H#MOGLOBIN. | 


When the blood crystals of horses’ blood are prepared in closed 
vessels, it happens very frequently that large quantities of hexagonal 
tables of a dark red colour ave found mixed with the well-known ordinar y 
prisms. If a drop of the liquid in which the crystals are suspended be 
examined with the microscope, without a cover-glass, the hexagonal plates 
are observed rapidly to liquefy, and simultaneously bundles of fine, 
bright-red prismatic needles appear. Nencki long ago showed that the 
dark red hexagonal tables are crystals of reduced hemoglobin, whilst 
the scarlet prisms are those of oxyhwemoglobin. Horses’ blood appears 
peculiarly apt to give crystals of the reduced blood- colouring matter. 
In the preparation of the hemoglobin of the horses’ blood by ordin: wy 
methods, i.e. without special precautions in reference to the access of 
air, both forms of crystals are usually obtained.t 


THE ABSORPTION OF LIGHT BY SOLUTIONS OF REDUCED HAMOGLOBIN. 


Colour of solutions: dichroism.—In thick layers, or in thin layers 
if concentrated, solutions of reduced hemoglobin present a dark cherry- 
red colour, whilst very dilute solutions exhibit a green tint. 


OXYHEZMOGLOBIN. TH MOGLOBIN. 
G L 
0-9 0-9 
0-8 0-8 
0:7 0:7 
0-6 0-6 
0-5 0:5 
0-4 0-4 
0-3 0-3 
0-2 0-2 
O-1 O-1 
fo) -$——O 
ABC D Epa G i ABC D [le G L 


Fic. 34.—Graphic representation of the spectrum of—(1) oxyhemoglobin 
and (2) hemoglobin. The numbers at the right-hand side of each 
diagram indicate percentages.—After Rollett. 


This dichroism is also characteristic of the blood of asphyxiated 
animals, and was first observed by Briicke. J¢ is specially to be noted 
that, whilst solutions of reduced hemoglobin are dichroic, solutions of the 
O,- CO- and NO-compounds of hemoglobin exhibit no trace of dichroism. 

Cause of the differences observed in the colour of blood contrasted 
with that of solutions of hemoglobin—The much brighter colour pre- 
sented by blood, as contrasted with corresponding solutions of the blood- 
colouring matter, depends upon the presence of the blood corpuscles. 
Were we to conceive, as Rollett argues, the blood corpuscles suspended 
in the liquor sanguinis or in serum, and retaining all their physical 
properties save their colour, then, as a result of the repeated total reflec- 
tions, due to the differences in the refractive indices of the corpuscles 
and the fluid in which they float, blood would appear as white as milk. 


1 Hiifner, op. cit., Arch. f. Physiol., Leipzig, 1894, S. 150. 


234 HAEMOGLOBIN. 


But these total reflections do go on in the case of the actual coloured 
corpuscles in a precisely similar manner to that which would occur in 
the hypothetical case just discussed; and the light reflected by them 
is conditioned by, and corresponds to, the absorption of the spectral 
colours exerted by the hemoglobin and the oxyhemoglobin respectively. 

The visible spectrum of reduced hemoglobin.—It has already 
been stated that, when a solution of oxyhemoglobin is reduced, the 
two absorption-bands « and § disappear and are replaced by a single 
one (y) situated between D and E, which is less deeply shaded and 
possesses less sharply-defined edges (see Plate I., Spectrum 5). This 
summary description must now be supplemented. 

The right-hand diagram on p. 233 exhibits fairly accurately the 
absorption of light by solutions of reduced hemoglobin of varying con- 
centrations. The single absorption-band (7), though occupying in solutions 
of from 0-2 to 0-4 per cent. and 1 cm. in thickness, the greater part of 
the space between Frauenhofer’s lines D and E, has its centre or darkest 
region rather nearer D than E. According to my own measurements, 
the darkest part of the band corresponds approximately to A 550. 

It is to be noted that solutions of reduced hemoglobin have a much 
greater absorptive power for the rays between A and B, and a smaller 
absorptive power for those between F and G, than corresponding solu- 
tions of oxyhzemoglobin. 


THE SPECTROPHOTOMETRIC CONSTANTS OF REDUCED HA&MOGLOBIN. 


In his most recent researches, Hiifner has determined the spectro- 
photometric constants of hemoglobin for the same spectral regions as 
were selected by him, in the same researches, for the determination of 
the constants of oxyhemoglobin. 

In the case of reduced hemoglobin the respective extinction-co- 
efficients are distinguished as ¢, and ¢’,, and the corresponding absorp- 
tion relations as 4, and J’,. 

The following are the results of Hiifner’s determination :!— 


A ae 
(\ 554—A 556) (\ 531-5-\ 542°5) 
0-001354 | 0:001778 


, 
r 


The quotient = is a constant of special importance; it is 0°7617. 
i 


The value of the quotient * has also been determined by Hiifner ;+ it 
is 0°6541. 

The determination of the amount of oxy- and reduced heemo- 
globin when both are present.—Vierordt pointed out that the absorption 


1G. Hiifner, ‘‘Neue Versuche zur Bestimmung der Sauerstoffcapacitét des Blutfarb- 
stoffs,” Arch. f. Physiol., Leipzig, 1894, S. 140. 


SPECTROPHOTOMETRIC DATA. 235 


of light (as determined by the extinction-coeflicient) in a definite spectral 
region, exerted by a mixture of two or more colouring matters, is the sum of 
the extinction-coefficients of each of its coloured constituents; and that in 
the case of a solution containing fo colouring matters, if we are acquainted 
with the optical constants of each in two and the same spectral regions, we are 
able by the spectrophotometer to determine the relative and absolute amount 
of each constituent. In a similar manner we should, according to theory, 
be able to determine the amounts of three or of # colouring matters coexisting 
in a solution, if we were acquainted with the value of A in three and the same, 
or in x and the same spectral regions. The immense importance of a method 
which permits of the accurate determination of oxy- and reduced hemoglobin 
in blood, and which furnishes us with essential data for calculating the 
amount of oxygen present in combination with hemoglobin, makes it 
necessary that we should explain the nature of the very simple calculations 
which enable us, from the determination of the extinction-coefficients in two 
spectral regions, to effect a determination which, so far as I know, cannot 
be carried out with any pretence to scientific accuracy, or even with any claim 
to be presumably correct, by any other process whatsoever. 

We shall assume that, by following methods which we shall not attempt 
to describe, but for which the reader is referred to Hiifner’s original papers, 
blood has been diluted with 0-1 per cent. of aqueous solution of NaOH, 
under conditions which preclude the possibility of contact with oxygen, and 
that in the diluted blood solution the extinction-coefficients have been deter- 
mined in the first and in the second regions selected by Hiifner. These 
extinction-coefficients of a mixture of two colouring matters, we shall represent 
by # and £.’ 

Let A, be the absorption relation of (reduced) hemoglobin in the first 
region (A 554 —A 556). 
A’, that of the same body in the second spectral region (A 531°5 — 
d 542°5). 
A, the absorption relation of oxyhemoglobin in the first spectral 
region. 
A’, that of the same body in the second spectral region. 


Then the percentage of (reduced) hemoglobin, which we may designate z, will 
be found by the equation— 
pa ArAr (E' A',—EA,) 
A’, A,—A, A’, 


and the percentage of oxyhzemoglobin by the following equation— 


404’ (EA, —E' A’) 
Wes at ae 


Having thus determined by spectrophotometry the amount of oxyhemoglobin 
by weight existing in a known volume, say 100 e¢.c. of blood, we can ascertain 
the volume of the respiratory oxygen measured at 0° C. and 760 mm. pressure 
(which could, but probably with less accuracy, be likewise determined with the 
aid of the mercurial pump and subsequent analyses of the gases boiled out of the 
blood) by multiplying each gramme of oxyhemoglobin found by 1:338 (or 1°34). 
In this manner Hiifner, having determined the relative and absolute amounts of 
hemoglobin and oxyhemoglobin in the blood, drawn simultaneously from the 
main artery and vein of a limb, ascertained the amount of oxygen in each. 
There is a strong presumption that determinations of oxygen made in this manner 
are nearer the truth than those which the more complex and laborious methods 
by means of the mercurial pump and gas analysis are capable of giving. In the 
process of raising the blood to a temperature of at least 40° C. in the exhausted 


236 HEMOGLOBIN. 


chamber connected with the mercurial: pump, some of the oxygen must be used 
up in oxidising the readily oxidisable substances existing in the blood, and 
especially in venous blood, and an error will be thereby introduced unequally 
affecting different samples of blood,—an error which is influenced by the 
duration and extent to which the heat is applied to the blood and the rapidity 
with which the aqueous vapour and gases evolved by the blood are removed. 


The photographic spectrum of reduced hemoglobin. — When 
the molecule of dissociable oxygen is removed from oxyhemoglobin, 
either by the action of reducing agents, or by boiling in vacuo, the 
absorption-band in the extreme violet is remarkably displaced towards 
the less refrangible end of the spectrum, the centre of absorption 
corresponding to ~ 4260. The difference in the position of Soret’s 
band in the oxy- and in reduced hemoglobin is shown in the photo- 
type (Fig. 53). When we reflect that the addition of a molecule of 
oxygen to the enormous molecule of hemoglobin cannot affect in an 
appreciable manner the mass of the molecule, we must conclude that 
the displacement of the absorption-band towards the ultra-violet end 
when hemoglobin combines with oxygen (all other conditions remaiming 
the same), indicates that this combination leads to a notable acceleration 
of the motion of the intramolecular group of carbon atoms upon which 
the extreme violet absorption-band depends. 

The amount of oxygen with which hemoglobin combines to 
form oxyhemoglobin.—It is believed, on various grounds, that one 
molecule of hemoglobin combines with one molecule of oxygen to form 
the compound which we know as oxyhzemoglobin. 

The most recent determinations made by Hiifner have shown that 
1 erm. of reduced hemoglobin of the ox ean link to itself 1538 c.c. of 
oxygen or carbonic oxide (measured at 0° C. and 760 mm. pressure). 
The molecular weight of the hemoglobin of the ox (calculated from 
Hiifner’s most recent estimations of the iron which this body contains) 
=16669. The volume of oxygen absorbed by reduced hemoglobin, 
calculated from this molecular weight, should be 1°54 cc., so that the 
result of experiment agrees in a surprising manner with theory. 

Differences in chemical reactions between solutions of reduced 
and oxyhemoglobin.—1. Solutions of reduced hemoglobin when boiled 
in vacuo, or subjected to the action of CO, unlike solutions of oxyhzmo- 
globin, yield no oxygen. 

2. They are not decomposed even by long contact with trypsin, which 
readily splits up oxyhemoglobin into hematin and the products of 
trypsin proteolysis. 

3. They are unaffected by H,S, which, when acting for a sufficient 
length of time upon oxyhemoglobin, converts it into sulpho-methemo- 
globin. 

4, Nitrites, potassium ferricyanide, and permanganate, and many 
other oxidising and reducing agents, exert no action on reduced hemo- 
globin, whilst they convert oxyhzemoglobin into methemoglobin. 

5. When treated with alcoholic or watery solutions of acids or 
alkalies, in the complete absence of free oxygen, hemoglobin yields 
purple-red solutions or precipitates. The hemoglobin is, under these 
circumstances, split up into an iron-containing coloured body—/emo- 
chromogen—and into an albuminous body or bodies. Oxyhemoglobin, 
under the same conditions, splits up into an iron-containing body— 
hematin—and albuminous products. 


COMPOUNDS OF HAMOGLOBIN WITH GASES. 237 


Non-existence of the so-called “ pseudo-hemoglobin.”—A fter 
treating blood with reducing agents until the two bands of oxyhemoglobin 
were no longer visible, Siegfried! found that there yet remained oxygen 
removable by boiling in a barometric vacuum. He therefore concluded that, 
in addition to oxyhemoglobin, there existed another oxygen compound of 
hemoglobin, and that this is characterised by the same absorption spectrum as 
reduced hemoglobin. To this hypothetical body he gave the name of pseudo- 
hemoglobin. Its existence has been absolutely disproved by Hiifner.2 The 
mistake into which Siegfried fell illustrates the danger of drawing conclusions 
from qualitative spectroscopic observations. Hiifner has shown that without 
spectrophotometric determinations it is impossible to know whether a solution 
of blood or of hemeglobin is completely reduced. The only reliable criterion 
is to be obtained by determining the values of e¢, and €’, so as to ascertain the 
quotient ** which should = 0-7617. 

€ 

Blood which has been proved to be completely reduced in this manner, 

yields no trace of oxygen when boiled in a mercurial pump. 


THE COMPOUNDS OF H&MOGLOBIN WITH CARBONIC OXIDE AND NITRIC 
OXIDE, AND THEIR RELATION TO OXYHAMOGLOBIN. 


Introductory remarks.—In a previous part of this article, I have 
referred to oxyhemoglobin as an easily dissociated compound, formed 
by the linking of one molecule of oxygen to a molecule of the highly 
complex, iron-containing, crystalline colouring matter, “ hzemoglobin,” 
and I have subsequently shown that this conception has received con- 
firmation through the fine researches of Hiifner on the molecular 
weight of hemoglobin and on the volume of oxygen with which it 
can combine. In the present section, reference must be made to ad- 
ditional facts which, besides possessing an interest of their own, throw 
fresh light on the nature of oxyhemoglobin, and, in a measure, on the 
function subserved by it, although this subject will be more fully dis- 
cussed under the heading of “ Respiration.” 


It had been noticed independently by Claude Bernard? and by Hoppe,t 
that blood which had been treated with carbonic oxide, or the blood of 
men and animals asphyxiated by charcoal fumes, presents an intensely bright 
arterial colour, but that, unlike arterial blood, it does not in a few hours change 
to a venous hue, but retains its vermilion tint for long periods of time. The 
idea forced itself on the minds of both Claude Bernard and Hoppe, that through 
the action of CO the power which the coloured corpuscles possess of acting as 
oxygen-carriers had in some way been interfered with. Claude Bernard has, 
however, the merit of being the first to show that, when brought in contact 
with the blood, CO is absorbed and displaces oxygen ; and he afterwards based 
upon these facts a method for the quantitative determination of the oxygen of 
the blood. 

At the same time as, and independently of, Bernard, Lothar Meyer® 


1 “Ueber Himoglobin,” Arch. f. Physiol., Leipzig, 1890, Phys. Abth., S. 385. 

2 “Bestimmung der Sauerstoffcapacitit des Blutfarbstoffs,” ibid., 1894, Phys. Abth., 
S. 140 and 175. 

* “*Lecons sur les effets des substances toxiques et médicamenteuses,” Paris, 1857, 
p. 158 ; also ‘‘ Propriétés des liq. de Vorganisme,” Paris, 1859, tome i. p. 355. 

* “Ueber die Einwirkung des Kohlenoxydgases auf das Haimatoglobulin,” Virchow’s 
Archiv, 1857, Bd. xi. S. 288. 

° “Die Gase des Blutes,” Gottingen, 1857; and Ztschr. f. rat. Med., 1858, S. 256; 
‘*De sanguine oxydo carbonico infecto,” Diss. Inaug., Vratislaviw, 1858. 


238 HEMOGLOBIN. 


showed—(1) that the absorption of oxygen and carbonic oxide by blood does 
not proceed according to Dalton and Henry’s law—a proof, amongst many 
others, that these gases are chemically combined with some constituent of 
the blood and not held in a state of simple solution ; (2) that blood which 
has been deprived of its gases by boiling 7m vacuo, combines with the same 
volume of carbonic oxide as of oxygen—in other words, that when carbonic 
oxide replaces the oxygen of the blood, one molecule of the former takes the 
place of one molecule of the latter (i.e. CO replaces O,). Lothar Meyer 
further showed that hematin could not be the body with which O, and CO 
entered into combination, and expressed the surmise that it might prove 
to be the same as constituted the red blood crystals described by Lehmann.! 
The truth of the surmise was soon proved beyond the possibility of doubt, 
it being shown that the O,- and CO-compounds of the blood-colouring matter 
are isomorphous, that they are characterised by a similarity in their power of 
absorbing light, but that the CO-compound is distinguished by not being 
decomposed by reducing agents (Hoppe-Seyler). 


Hermann 2 subsequently showed that just as CO possesses the power 
of displacing the oxygen of oxyhzmoglobin, nitric oxide (NO) in its 
turn is capable of displacing CO, one molecule of the former replacing 
one molecule of the latter, the NO-compound being, like the CO-com- 
pound, absolutely irreducible. . 

The three compounds of hemoglobin were shown to be isomorphous, 
to be characterised by a highly florid colour, only slightly differing in 
tint one from the other; their visible spectrum was found to be distin- 
guished by two absorption-bands between D and E, at first sight appear- 
ing identical in the three cases, though careful measurement revealed a 
very slight shifting of the bands towards the more refrangible end of the 
spectrum in the case of the CO-compound. 

They were all three found to be free from pleochromatism— 
a character in which they differ strikingly from reduced haemo- 
globin. Whilst the CO-compound is much more stable than the 
O,-compound, the NO-compound is again more stable than the CO- 
compound. 

It was at first believed that the CO-compound, unlike oxyhzmo- 
globin, could not be dissociated. I was the first to show that by the 
long-continued passage of neutral gases through solutions of CO-hemo- 
globin, the CO is gradually driven out, and reduced hemoglobin is 
obtained. Donders,t to whom the discovery of the fact is always 
ascribed, drew attention to it in a highly interesting theoretical paper. 
Zuntz® immediately afterwards showed, in contradiction of Nawrocki,® 
that blood saturated with carbonic oxide, when boiled in vacuo, gives up 
its carbonic oxide and that it manifests the absorption-band of reduced 

1 «* Consideranti enim que his in rebus din versatus Lehmann de rubris illis sanguinis 
erystallis nuper publicavit, plus quam verisimile videbitur, hac cum substantia et oxygenium 
et oxydum carbonicum conjunctionem chymicam posse inire”; Lothar Meyer, “De 
sanguine oxydo carbonico infecto,” p. 12. 

2 <*Ueber die Wirkungen des Stickstoffoxydgases auf das Blut,” Arch. f. Physiol., 
Leipzig, 1865, S. 469. 

3A. Gamgee, ‘‘On Poisoning by Carbonic Oxide Gas, and by Charcoal Fumes,” 
Journ. Anat. and Physiol., London, 1867, vol. i. pp. 339-346. 

4 Donders, ‘‘ Der Chemismus der Athmung, ein Dissociations-process,” Arch. f. d. ges. 
Physiol., Bonn, 1872, Bd. v. S. 20-26. 

5 “Tst Kohlenoxydhamoglobin eine feste Verbindung?” Arch. f. d. ges. Physiol., 
Bonn, 1872, Bd. v. S. 584-588. 


6 << De Claudii Bernardi methodo oxygenii copiam in sanguine determinandi,” Inaug. 
Diss., Vratislavie, 1863. 


CARBONIC OXIDE HAMOGLOBIN. 239 


hemoglobin, and Podolinski! succeeded in dissociating blood saturated 
with nitric oxide, by passing a stream of hydrogen through it for an 
hour and a half; at the end of which time the blood presented the 
absorption-band of reduced hemoglobin. 

Having passed in review the chief facts which exhibit the relation- 
ship existing between the different compounds of hemoglobin, and which 
illustrate the nature of the combination of hemoglobin with gases, some 
of the characters and properties of CO-hemoglobin and NO-hemoglobin, 
but particularly of the former, must be systematically though briefly 
described. 


CARBONIC OxIDE Hamoc opin (CO-H &MoGLostn). 


Mode of preparation.—A current of pure carbon monoxide is passed 
through a saturated solution of oxyhemoglobin. The solution acquires a 
carmine-like tint in contrast to the scarlet colour of oxyhemoglobin. This 
solution is then cooled to 0° C., and, after being treated with one-fourth of 
its volume of alcohol previously cooled to 0° C., is set aside at a tempera- 
ture which must not rise above 0° C., but which should be as low as possible. 
After some hours or days, the CO-compound, which is more sparingly soluble 
than O,-hemoglobin, separates in crystals, of which the forms are identical 
with those of that body. 


The absorption of light by CO-hzemoglobin.—(a) The visible 
spectrum. —Solutions of this body possess more of a bluish-red tint 
than the O,-compound. If solutions of equal concentration of the 
oxygen and carbonic-oxide compounds be compared, it will be found, on 
spectroscopic examination, that the CO-compound absorbs the blue rays 
of the spectrum to a less degree than oxyheemoglobin. 

Between D and E are seen two absorption-bands which, unless very 
closely studied, appear absolutely identical with those of oxyhemo- 
globin (see Plate I, Spectrum 6). On careful measurement, however, it 
is seen that both the bands are very slightly shifted in the direction 
of E; that is to say, towards the violet end. This is best seen by 
noticing the interval between D and the adjacent border of the first 
absorption-band ; in the case of the CO-compound this interval is broader 
than in that of the O,-compound. 

The spectrophotometric constants of CO-hzemoglobin.—These 
constants were re-determined by Hiifner in 1894, at the same time as 
those of oxy- and reduced hemoglobin, and for the same spectral 
regions, with the results exhibited below.? The coefficients of extinction 
in the case of CO-hzmoglobin are designated for the region 4 554—2 565, 
«, and for the region % 5315-A 542°5 €,, whilst the corresponding 
absorptive relations are designated A, and A’.. 


A, | Ay, 


A 554-A 565 4 X 531°5-r 542°5 


0001383 | 0001263 


* “ Ueber die Austreibbarkeit des CO- und NO- aus dem Blute,” Arch. f. d. ges. Physiol., 
Bonn, 1872, Bd. vi. S. 553-555. 
* Hiifner, op. cit., S. 141 and 142. 


CO-H&MOGLOBIN, 


O, HaMoa.osin. 


240 HAMOGLOBIN. 


(4) The photographic spectrum of CO-hzmoglobin.—In Fig. 35 
are shown reproductions of the photographic spectrum of this com- 
pound, contrasted with that of the oxygen compound. The band of 
Soret is just as well marked in the one as in the other, but in the 
case of the CO-hzmoglobin there is a decided shifting of the band 
in the extreme violet towards the red, which is somewhat curious, 
considering that the bands in the visible spectrum are, though to a 
much less extent, shifted in the opposite direction. I have shown that 
there is absolute identity in the position of the absorption-band in the 
extreme violet, in the case of the CO- and NO- compounds of heemoglobin.1 

The principal characteristic reactions of CO-hemoglobin. 
1. When treated with Stokes’ reagent, solutions of ammonium sulphide, 
and the lke, no change whatever occurs, either in the colour or the 
spectrum of blood saturated with carbonic oxide, or in solutions of 
pure CO-hzmoglobin. 


G HK LM N O 


Freee 


i 
\ 
) 
: 
2 


Mbagrmaieer rte to ont 


bg ance 


Fic. 35.—The photographic spectrum of oxyhemoglobin and of CO-hemoglobin. 


2. The blood of men or animals asphyxiated by carbonic oxide, or 
by a gas containing it (charcoal fumes, coal gas), if pretty fully saturated, 
possesses and retains for a long time a florid arterial colour, and when 
diluted is found to be (Sa or completely irreducil sle. Hoppe- 
Seyler found that if such blood is sealed in glass tubes, it may retain for 
some years its characteristic spectroscopic properties, and even admit 
of CO being boiled out, with the aid of the mercurial pump, and 
enue) by chemical analysis. 

. The addition of a concentrated solution of sodium hydrate (density 
1:3) - blood, saturated with CO in the proportion of about two parts 
of the former to one of the latter, causes the blood to assume a fine 
scarlet colour, and to deposit a cimnabar-red precipitate. The same 
coloration and precipitate is produced with solutions of pure CO- 
hemoglobin. According to Hoppe-Seyler, the precipitate is composed. 
of CO-hemoglobin, rapidly passing into CO-hemochromogen. When 
normal blood is treated in the same way with sodium hydrate, it is 

1Gamgee, Proc. Roy. Soc. London, 1896, vol. lix. p. 276. 


NITRIC OXIDE HEMOGLOBIN 241 


converted into a black shining mass, which when spread in thin layers 
over porcelain appears of a greenish-brown colour. 

4, Aqueous neutral solutions of pure CO-hemoglobin, when heated 
to boiling point, furnish a bright red precipitate, composed of coagulated 
albuminous substances and CO-hzmochromogen (Hoppe-Seyler). 

5. Solutions of carbonic oxide hemoglobin, treated with NO in the 
absence of oxygen, are at once decomposed, and liberate CO (Hiifner). 


Nirric OxtpeE Hamoanopin (NO-Ha:mocropm). 


Mode of preparaticn.—So great is the affinity of nitric oxide for oxygen, 
that, when it comes in contact with it, deep red fumes of nitrogen peroxide, NO,, 
is formed. When this gas comes in contact with water, the decomposition 
indicated in the following equation occurs :— 


3NO, + H,0 = 2HNO,+ NO. 


But as all free acids decompose the colouring matter of the blood, before 
causing nitric oxide to act upon blood certain precautions must be taken ; 
for even if atmospheric oxygen be eliminated and nitric oxide caused to act 
upon oxyhemoglobin, nitrous oxide would be formed at the expense of the 
oxygen of that body; and next, by the action of water, nitric acid, which 
would immediately decompose the hemoglobin. 

Two methods of proceeding are open to us—(a) To add to the solution of 
oxyhemoglobin which is to be subjected to the action of nitric oxide, sufficient 
alkali to neutralise the nitric acid which will be formed. Such a solution 
must be placed in a flask, permitting of the whole of the air above the solution 
being driven out and replaced by a neutral gas, before allowing access to the 
nitric oxide. After the latter has exerted its action, care must be taken again 
to pass a neutral gas through the apparatus and solution, so as to remove all 
traces of free nitric oxide. 

(6) The solution of oxyhemoglobin is subjected to the long-continued 
action of carbonic oxide, so as to form CO-hemoglobin and to expel all traces 
of dissolved oxygen. Otherwise, the process is constructed as described 
under (a). This process would be certainly preferred, if it were desired to 
crystallise the NO-compound. 


Physical and chemical characters.—Blood saturated with nitric oxide 
possesses almost as florid a colour as CO-blood, though Hermann says 
that it does not present the slight bluish shade of the latter. It exhibits 
no dichroism. Solutions of N O-hemoglobin, or diluted N O-blood, 
exhibit a visible spectrum in which, as I have convinced myself, the 
bands occupy precisely the position of the two oxyhemoglobin bands. 
In the photographic spectrum, however, the band in the extreme violet 
exhibits absolute coincidence with that of CO-hzmoglobin. 

NO-hemoglobin can be crystallised, and, as Hermann showed, the 
crystals are identical with those of oxyheemoglobin and CO-hzemoglobin. 


ALLEGED (BUT PROBLEMATICAL) Compounps or H&MoGLOpIN 
WITH GASES. 


1. With hydrocyanic acid.—The most discrepant statements have 
been made in reference to the very simple question—whether hydrocyanie 
acid added to, or passed through, blood affects the characters of its absorption- 
spectrum. In spite of these, it may be definitely stated that, at ordinary 
temperatures, and when acting for moderate periods, hydrocyanic acid leads 


VOU —— 116) 


242 HAMOGLOBIN. 


to no change in the physical characters of the blood, of which the spectrum 
remains unchanged, and of which the property of being reduced by suitable 
agents remains unaffected. 

Upon what appears to me to be altogether insufficient evidence, Hoppe- 
Seyler,! however, came to the conclusion that hydrocyanic acid forms an easily 
decomposed compound with hemoglobin. If hydrocyanic acid be added to 
a solution of oxyhzemoglobin, on crystallising out the latter it retains some of 
the acid. These crystals may be repeatedly crystallised, and when dried in 
vacuo over sulphuric acid they are found to contain hydrocyanic acid. The 
supposed compound of hydrocyanic acid with oxyhemoglobin presents an 
absorption-spectrum absolutely identical with that of oxyhemoglobin, and is 
reduced just as easily by such agents as ammonium sulphide or Stokes’s re- 
agent. On the other hand, blood to which hydrocyanic acid has been added 
shows the bands of oxyhemoglobin for a much longer time than normal blood. 

It appears to me that no proof whatever has been advanced of the 
existence of a chemical compound of oxyhemoglobin with HCN. 

That some hydrocyanic acid should adhere to hemoglobin, as it erystallises 
out of the mother liquor which contains the acid, is quite in accordance with 
a number of experiences of a similar kind, and can by itself afford no evidence 
of an actual compound existing. The resistance of blood to which hydro- 
eyanic acid has been added, to decomposition, when confined in a sealed or 
closed vessel, can, on the other hand, be easily explained by the unquestion- 
able arrest or slowing of the process of putrefaction in the presence of hydro- 
cyanic acid. It is, undoubtedly, the products of putrefaction which are the 
causes of the apparently spontaneous reduction of the oxyhemoglobin of blood 
contined in a receptacle to which air has no access; so that an agent which 
does inhibit putrefaction—as hydrocyanic acid unquestionably and admittedly 
does—and, at the same time, does not, at ordinary temperatures, decompose 
oxyhemoglobin, would be expected to act as hydrocyanic acid has been found 
to do in furthering the persistence of the oxyhemoglobin bands. 

What I have just stated in reference to the probable non-existence of a 
compound of HCN with oxyhemoglobin, does not imply my disbelief in the 
existence of an interesting compound of hydrocyanic acid with methzemo- 
globin, described by Kobert, which will be discussed after the latter body 
has been described. 

2. With cyanogen.—Ray Lankester? believed that cyanogen formed a 
compound with hemoglobin, probably analogous to the CO- and NO-com- 
pounds, and characterised by an absorption-band, resembling that of, but 
obviously not due to, reduced hemoglobin. Many discordant statements have 
been published on this matter. It appears that by the prolonged action of 
cyanogen, as by the prolonged action of HCN, there is produced Kobert’s 
cyanogenmethemoglobin (see p. 248). 

3. With acetylene (C,H,.).—Bistrow and Liebreich * surmised that acety- 
lene forms a very unstable compound with hemoglobin, easily reducible by 
sulphide of ammonium and similar agents. On the evidence at present at our 
disposal, the existence of this compound must be considered as more than 
problematical. 

4, With carbon dioxide.— According to Bohr, hemoglobin forms a series 
of compounds with carbon dioxide, which possess spectra identical with those 
of reduced hemoglobin. He states, further, that if a solution of hemoglobin 
be brought in contact with a mixture of oxygen and carbon dioxide, the 


1 «« Cyanwasserstoffhemoglobinverbindungen,” Med.-chem. Untersuch., Berlin, 1868, S. 
206-208. 

2 “Ueber den Einfluss des Cyangases auf Hamoglobin nach spectroscopischen Beobach- 
tungen,” Arch. f. d. ges. Physiol., Bonn, 1869, Bd. ii. S. 491-493. 

8“ Ueber die Wirkung des Acetylens auf das Blut,” Ber. d. deutsch. chem. Gesellsch., 
Berlin, 1868, Bd. i. S. 220. 


PRODUCTS OF DECOMPOSITION. 243 


amount of either of these gases which is absorbed is independent of the 
other. 

A careful study of the whole of Bohr’s researches on this subject, as well 
as those on the various hypothetical compounds of hemoglobin with oxygen, 
has convinced me that his work is pervaded by fallacies, which spring in part 
from erroneous methods of work, in part from a non-appreciation of physical 
principles of which the exactitude is beyond dispute ; the discussion of Bohr’s 
statements in a text-book would be, under these circumstances, altogether out 
of the question. 


THE IMMEDIATE DERIVATIVES AND PRODUCTS OF DECOM- 
POSITION OF OXYHAMOGLOBIN AND REDUCED HA2MO- 
GLOBIN. 


Introductory observations.—It has already been stated, that when 
the blood-colouring matter is subjected to the action of strong alkalies 
and of acids, or even of salts possessing an acid reaction, or to the 
action of heat, of alcohol, and of many other chemical agents, it under- 
goes a decomposition of which the chief products are an albuminous 
substance or substances, and a colouring matter which contains the whole 
of the iron originally present in the oxyhemoglobin or hemoglobin 
decomposed. 

. Under ordinary circumstances, when oxyhemoglobin is decomposed in 
the presence of air, the coloured product of decomposition is the body 
we know as hematin, the amount of which produced corresponds theo- 


‘ retically to 3:8 per cent. of the oxyhemoglobin. Traces of organic 


acids are said to result from the decomposition, the main product. of 
which is, however, composed of the albuminous residue of the blood- 
colouring matter (vide infra). Tf, however, instead of decomposing 
oxyhemoglobin, we employ reduced hemoglobin and carry out the 
process in the complete absence of oxygen, we obtain, not hematin, but 
a body of which some of the optical characters were first described 
by Stokes, and which he named reduced hematin, to indicate that it 
may be obtained by the action of reducing agents on hematin. Instead 
of employing this term, it is better to adopt that of haemochromogen, 
introduced by Hoppe-Seyler, to whom we owe nearly all the knowledge 
we possess with regard to it. According to Hoppe-Seyler, heemochro- 
mogen constitutes the coloured radicle of the blood-colouring matter, 
upon which its essential optical properties and its property of com- 
bining with oxygen, carbonic oxide, and nitric oxide depend. 

Under the influence of carbonic acid, and very dilute acids acting 
for comparatively short periods of time, oxyhemoglobin, long before the 
complete splitting up into hematin, undergoes a change which is doubt- 
less of the nature of a decomposition ; this change is identical with that 
which is also brought about by a variety of oxidising agents, typically 
by ozone, nitrites, and potassium ferricyanide; to the. body which 
results, the name of methemoglobin has been given. It will be con- 
sidered first amongst. the decomposition products of oxyhzemoglobin. 
We shall show it to be a substance which is formed in the living body, 
under the influence of certain poisonous agents, and is occasionally 
found in old blood extravasations ; it possesses the power of forming 
molecular compounds with certain bodies, such as nitrites,’ hydrocyanic 
acid, and cyanogen. 


244 HEMOGLOBIN. 


THE ALBUMINOUS RESIDUE OF THE BLOOD-CoLOURING MATTER. 


An unfortunate error has become popular, and has, indeed, been 
propagated by a large number of text-books, namely, that when oxy- 
hemoglobin is decomposed, it splits up into hematin and a definite 
albuminous matter belonging to the group of globulins, and designated 
globin. There is absolutely no ground for such a statement. The term 
globin was, it is true, assigned by Preyer to an albuminous substance, 
which he obtained as a product of the spontaneous decomposition of 
solutions of oxyhzemoglobin, but this body did not possess the character- 
istic properties of the globulins, and there is no ground for considering 
it as representing the albuminous body which, by linking to itself a 
coloured iron-containing radicle, forms crystalline hemoglobin. 

Our knowledge on ‘this matter is indeed of the most unsatisfactory 
character. We know, and have shown (see p. 207), that solutions of oxy- 
hemoglobin in the presence of many of the reagents for albumin (so long 
as these do not decompose the blood-colouring matter) behave quite differ- 
ently from solutions of the native albumins, globulins, ete. Thus copper 
sulphate, mercuric chloride, silver nitrate, and the acetates of lead do 
not produce even a cloudiness when added to solutions of pure heemo- 
globin, so long as this remains undecomposed. It has long been recog- 
nised, too, that Lehmann’s hypothesis, that the blood-colouring matter 
was composed of colourless crystals tinted by a red pigment, was false ; 
but as to the true nature of the albuminous residue, we have very little 
knowledge, though the facts in our possession almost force us to the 
conclusion that it is not identical in all animals, as shown by the 
difference in the percentage of sulphur in the hemoglobin of the horse 
and the dog. 

The reagents which we employ to decompose the blood-colouring 
matter yield us derivatives of the albuminous residue, not the body 
itself ; we obtain acid albumin as a result of treatment with acids, alkaline 
albuminates as a result of treatment with alkalies. The most interest- 
ing observations on the albuminous products of the decomposition of oxy- 
heemoglobin were published by Kiihne! thirty years ago. He showed that 
when CO, is passed through solutions of pure oxyhzemoglobin a flocculent 
precipitate is thrown down, which does not possess, as had been errone- 
ously asserted by A. Schmidt, fibrinoplastic properties, and which does 
not behave as a globulin. According to Kiihne, this precipitate possesses 
so peculiar an appearance under the microscope that it cannot be mis- 
taken for any other substance. It forms long colourless fibres which 
are so like fibres of connective tissue that they might be taken for them. 
This substance differs fundamentally from globulin; it is, for example, 
insoluble in water containing oxygen in solution. 


METH &MOGLOBIN. 


Hoppe-Seyler was the first? to observe that solutions of oxyhzemo- 
globin exposed to the air, or filter papers saturated with such solutions, 
often assume a brown colour. Under these circumstances, the solution 


1 “«Tehrbuch,”’ 1866, S. 206, 207. 

* Centralbl. f. d. med. Wissensch., Berlin, 1864, No. 53. See also Med.-chem. Unter- 
such., Berlin, 8. 378, und ‘‘ Die Zusiimmensetzung des Methimoglobin, und seine Umwand- 
lang | zu Oxyhamoglobin, ” Zischr. f. physiol. Chem.., Strassburg, 1878, Ba. ii. S. 150, 155. 


METHAEMOGLOBIN. 245 


is found to have become acid and to exhibit a spectrum in which, in 
addition to the two bands of oxyhemoglobin, one is seen in the red, 
occupying much the position of the band of acid hematin. 

Hoppe-Seyler applied the name of methemoglobin to the very 
indefinite and problematical body whose solutions possessed the above 
characters, and held it to be a product of the partial reduction of 
oxyhemoglobin, derived from it by the removal of a portion of the 
dissociable oxygen of that compound. 

I myself, soon after, investigated the changes brought about in the 
properties of oxyhemoglobin under the influence of nitrites, and in a 
memoir, of which the experimental facts have, so far as they have yet 
been controlled, been confirmed in every particular, pointed out the 
remarkable phenomena which attended the conversion of oxyhemoglobin 
into methzemoglobin, though I committed the error of believing that the 
changes described by me were due to the combination of nitrites with 
oxyhzmoglobin, and not to an action which was afterwards shown to be 
possessed by a large number of both oxidising and reducing substances. 
I showed that blood which had been acted upon by nitrites, in addition 
to marked and definite changes in colour and spectrum, had almost 
entirely lost its power of absorbing oxygen from the atmosphere; that, 
under the influence of nitrites, the oxygen of oxyhemoglobin 7s not 
removed, but passes into a condition in which it is no longer removable 
by boiling im vacuo or by the action of carbonic oxide. The action 
of reducing agents reveals, however, as I showed, that the molecule 
of loose oxygen of oxyhemoglobin is still present in blood which 
has been acted upon by nitrites, for, in the absence of all traces 
of oxygen, reducing agents first of all and instantaneously liberate 
oxyhemoglobin, which is only afterwards reduced. I pointed out that 
the chocolate-coloured nitrite blood can be crystallised, the colouring 
matter being isomorphous with hemoglobin and its compounds, and 
that the crystals contain the nitrite which has brought about the 
change, though I showed that the composition of these molecular com- 
pounds of oxyhemoglobin is not a constant one. After innumerable 
contradictions, it has been proved, though without a word of acknow- 
ledgment, mainly by the researches of Hiifner and his pupils, that my 
account of the changes which characterise the formation of methemo- 
globin was, in every particular, exact, whilst the comparatively recent 
statement, by Kobert, of the existence of combinations of hydrocyanic 
acid and cyanides with methemoglobin is an illustration of the class 
of compounds of oxyhzemoglobin which I was the first to discover and 
describe, and of which doubtless a large number will be obtained. 


Mode of preparation.—A large number of imorganie and organic bodies, 
acting upon solutions of oxyhemoglobin, convert it into methemoglobin. 
The chief of these are potassium ferricyanide—which, on account of the 
rapidity of its action, is to be preferred to all others—nitrites, chlorates, 
potassium permanganate, nitrobenzol, pyrogallol, pyrocatechin, acetanilid, etc. 

In order to study the spectroscopic characters of methemoglobin, a 
solution of diluted blood is treated with a few drops of a strong solution 
of potassium ferricyanide, when the change in colour and spectrum is seen to 
occur almost instantly. To prepare the crystalline colouring matter, 2 or 
3 cc. of a saturated solution of potassium ferricyanide or ‘of a nitrite is 


1 A. Gamgee, ‘‘On the Action of Nitrites on Blood,” Phil. Trans., London, 1868, vol. 
elvili. pp. 589-626. 


246 HAMOGLOBIN. 


added to a litre of saturated aqueous solution of crystals of oxyhemoglobin, 
and after the conversion into methemoglobin has occurred, about 25 per cent. 
of alcohol added. The mixture is then exposed to a temperature below 0° C. 
I succeeded in recrystallising methemoglobin prepared by the action of 
potassium nitrite and of ethyl and amyl nitrites on oxyhemoglobin. 


Chemical and physical characters—Crystals of methemoglobin are 
more sparingly soluble than those of oxyhzemoglobin, and the colorifie 
intensity of their solutions is less. 

It is to be noted that, whilst solutions of reduced and oxyhemoglobin 
are not precipitated by either neutral or basic lead acetates, these 
reagents added cautiously, with careful avoidance of an excess, precipi- 
tate methemoglobin, hematin, and hematoporphyrin, and may be em- 
ployed for the separation and detection of traces of oxyhzmoglobin 
when mixed with and concealed by any of the above-mentioned bodies. 

Solutions of methemoglobin, when of a neutral or a slightly acid 
reaction, possess a chocolate-brown colour. When the solution is 
rendered alkaline, its colour changes to red without a tinge of the 
chocolate-brown. 

The acid solution is found to present a spectrum in which the oxy- 
hemoglobin bands « and 6 are very weak or even not visible, whilst an 
absorption-band is seen in the red between C and D, and nearer the 
former. This band occupies nearly, though by no means exactly, the 
position of a similar band in the spectrum of acid hematin (see Plate 
IL, Spectrum 5). 

On now rendering the solution alkaline by means of ammonia, the 
band in the red disappears, and is replaced by a faint absorption-band 
immediately on the red side of D. By changing the reaction of the 
solution, the alterations in its colour and spectrum may be repeated 
indefinitely (Gamgee). 

If a solution of methemoglobin be placed in a deep test tube, in 
front of a spectroscope, and arrangements be made for allowing a stream 
of solution of ammonium sulphide to flow to the bottom of the 
liquid, it can be readily shown that at the very moment of the 
contact of the reducing and the methemoglobin solution, the spec- 
trum of oxyhemoglobin appears; to be subsequently and much more 
slowly replaced by that of reduced hemoglobin, which in its turn, 
when shaken with air, yields oxyhemoglobin. 

A study of the photographic spectrum of methzmoglobin has led 
me to results of great interest. The conversion of oxyhzemoglobin into 
methemoglobin is attended by a shifting of the band of Soret from the 
extreme violet to the ultra-violet properly so called (Fig. 36). The most 
persistent part of the band in very dilute solutions, coincides, indeed, 
with the H and K bands, but the band extends more and more into the 
ultra-violet, as the concentration of the solution increases. The position 
and characters of this band in the case of methemoglobin absolutely 
corresponds with those of the acid compounds of hematin, and not 
with those presented by hemoglobin and its compounds, or by 
hemochromogen (see Fig. 38). 

This spectroscopic character certainly seems to lend weight to the 
evidence of other kinds, which indicates that methzmoglobin is a first 
product of the decomposition of the oxyhemoglobin molecule, and that 
this is a decomposition which leads to the separation of a compound of 
hematin, and not of hemochromogen. Hoppe-Seyler, indeed, expressed 


a ae 


OXYILEMOGLOBIN, 


METH AMOGLOBIN. 


METHAZMOGLOBIN. 247 


the opinion that the colouring matter in methemoglobin is in the same 
state as in hematin, the iron being, as he thought, in the condition of a 
ferric compound, ee alet t in oxyheemoglobin and in hemochromogen he 
believed it to exist in a ferrous state, though the grounds for these very 
definite statements are certainly wanting. 


The researches of Hiifner on the oxygen of methzemoglobin. 
—I had shown that the action of methemoglobin, as produced by the action 
of nitrites, could not be attended by a profound alteration in the constitution 
of oxy hemoglobin, seeing that the ‘addition of certain re agents at once caused 
all the effects of the action to disappear, and revealed the ‘continued existence 
of oxidised hemoglobin. Nitrites (for these we should now read all agents 
capable of transforming oxyhemoglobin into methemoglobin) had, by my 
experiments, been shown to resemble in no way those agents which thrust 
oxygen out of the blood ; on the other hand, I had shown that the action of 


G HK LM N O 


Fic. 36.—The photographic spectrum of oxyhemoglobin and methemoglobin. 
co) fo} t=} 


nitrites resulted in the locking up of the oxygen of the blood, so as to render 
it irremovable by carbonic oxide, or by a vacuum. But although I had dis- 
covered that methemoglobin, when treated with reducing agents, at once 
liberates oxyhemoglobin, | had not been able to show that when the latter 
substance is converted into the former the whole of its oxygen is locked up 
without loss, and may be subsequently liberated. This was reserved for 
Hufner. 

When nitric oxide acts upon a solution of methemoglobin, the brown 
colour is changed to bright red, the spectrum of the red solution being 
identical with that of NO- hemoglobin. Reflecting on this experiment, Hiifner 
thought that perhaps NO possesses the power of becoming oxidised to NO,, 
at the expense of the oxygen locked up in methemoglobin (i.e. oxygen of 
the original oxyhemoglobin which had passed into a more stable combination). 

As such might be the case, it occurred to Hiifner to determine the volume 
of NO, produced (for this wo ould bear a definite relation to the O abstracted 
from methemoglobin), by causing the nitrous acid (HNO,), which would 
be produced by the action of the water of the blood on NO,, to decompose 
urea, the N liberated being a measure of the oxygen derived from methemo- 


248 HAEMOGLOBIN. 


globin. The ingenious conception of Hufner will be rendered evident by the 
three following equations :— 


(1) 6NO + 2(H1b-0,) = 4NO, + 2(Hb-NO). 
(2) 4(NO,) + 2( (1,0) = 2(NO,H) + 2(NO,H). 
(3) 2(NO,H) +CH,N,O = 3(H,0) + 2CO, + 2(N,). 


From these equations it results that each molecule of nitrogen liberated 
will correspond to a molecule of oxygen which had become fixed in methemo- 
globin. 

Whether the more firmly combined oxygen of methemoglobin were capable 
of oxidising nitric oxide or not, the oxygen of oxy shemoglobin would certainly 
be able to do so, and Hiifner proceeded to compare the amount of N liberated 
in the above reaction by solutions of exactly corresponding concentration of 
oxyhzemoglobin and of alkaline methemoglobin. The results left no room for 
doubt, and led to the conclusion that when oxyhemoglobin is converted into 
methemoglobin, the whole of its oxygen passes into a state of more intimate 
combination, so that it can no longer be removed either by CO nor by a 
vacuum, but is yet available to oxidise such bodies as NO,,. 

The compounds of methemoglobin with nitrites.—I showed, as 
has already been stated, that when a solution of pure oxyhemoglobin is 
treated with a solution of a nitrite, so as to produce the change in colour 
and spectrum which we now know to be characteristic of methemoglobin, 
the blood-colouring matter crystallised out of the solution is found to con- 
tain the nitrite, though the proportion in which the latter combines with 
the hemoglobin is not constant. The discordance in results did not appear 
to me surprising, and that “as in the case of other combinations of a molecular 
kind, such as the union of salts with their water of crystallisation, of bases 
with sugar, of albumin with metallic oxides, of iodine with the compound 
ammonias, the amount of the simpler body added to the more complex should 
vary within wide limits.” I further speculated on the probability of a large 
number of similar combinations to that of oxyhemoglobin with nitrites 
existing. 

The compounds of methemoglobin with HCN and cyanides.— 
It has long been noticed that hypostatic marks on the bodies of men and 
animals poisoned by prussic acid or metallic cyanides, as well as the mucous 
membrane of the stomach, present a striking bright red colour. Kobert! 
surmised that this coloration might be due to combination of methemo- 
globin with HCN or metallic eyanides, a hypothesis of which he thinks 
he has obtained confirmation from his experiments. Kobert found that on 
adding solutions of HCN of extreme dilution to a 1 or 2 per cent. solution 
of methemoglobin, these assume a beautiful bright red colour, whilst the 
absorption band or bands of methemoglobin have disappeared, and are 
replaced by a single broad absorption-band between D and E, occupying about 
the position of the band of reduced hemoglobin. This band cannot, however, 
be made to disappear by the action of oxygen. 

According to Kobert, this band is not affected by the addition of ammonium 
sulphide. He believes the body which is produced by the action of HCN on 
methemoglobin to be a compound of the two bodies, and he ascribes to it the 
name “‘cyanogenmethemoglobin,” and represents it for brevity by the symbol 
CNH-MetHb. He further lays claim to have discovered for the first time 
similar compounds with nitrites (!!). But Kobert’s view of the nature of the 
action of HCN on methemoglobin has not been universally accepted. The 
absorption-spectrum which he has described as characteristic of his new 
compound is identical with that described by Preyer as resulting from the 


1“ Veber Cyanmethamoglobin und den Nachweis der Blausiure,” Stuttgart, 1891. 


SULPHO-METHAMOGLOBIN (?). 249 


action of HCN on oxyhemoglobin, and by Nawrocki and Lankester as pro- 
duced when KCN acts upon blood, especially with the aid of gentle heat, and 
which has generally been held to be a compound of cyanogen and hematin 
(cyanhematin). 

Szigeti! maintains that Kobert’s cyanogenmethemoglobin is in reality 
eyanhematin, the first step in the action of HCN being to split up the 
methemoglobin molecule into hematin and an albuminous substance. I do 
not, however, take this view, and, in spite of the evidence which Kobert has 
adduced being in many respects incomplete, I am inclined to think that the 
view which he has advanced is correct. In the first place, the certain existence 
of compounds of the nitrites with methemoglobin affords presumptive 
evidence of the strongest kind that similar compounds with such bodies 
as cyanogen, hydrocyanic acid, and cyanides exist ; in the second, the almost 
instantaneous action of solutions of hydrocyanic acid of phenomenal dilu- 
tion renders it highly improbable that the action of hydrocyanic acid on 
methemoglobin is one in which decomposition into hematin is a preliminary 
stage. 

There can be no question that HCN acting in the cold, and, for a short 
time upon, blood or on solutions of oxyhemoglobin, produces no change in the 
spectrum, and it is against all experience and analogy from the action of other 
dilute acids on either oxyhemoglobin or methemoglobin to conclude that 
solutions of HCN of extraordinary dilution should be able—and almost instan- 
taneously—to split up the oxyorthomethemoglobin molecule. Kobert has 
found that a solution containing 0:000003 grm. of HCN is able to produce the 
characteristic change in 1 c.c. of a 1 per cent. solution of methemoglobin. 
He has further shown that his assumed cyanogenmethemoglobin contains 
HCN which can be recovered from it without loss by distilling with sulphuric 
acid, 

CO-methzemoglobin.— According to Weyl and v. Anrep,’ this com- 
pound is produced when aqueous solutions of iodine and potassium iodide, 
or solutions of potassium permanganate, continue to act upon a solution of 
CO-hemoglobin for several days. This body is said to retain the red colour 
of CO-hemoglobin, and to present the same absorption-bands in its spectrum. 
I fail to understand the grounds for believing in its existence. 

Sulpho - methemoglobin. — This hypothetical body was believed by 
Hoppe-Seyler? to be the cause of the green coloration observed on the 
surface of putrefying organs. 

Sulphuretted hydrogen has no action on reduced hemoglobin. When 
acting in small quantities on neutral solutions of pure oxyhemoglobin, it 
reduces these. If, simultaneously, a stream of sulphuretted hydrogen and 
oxygen be passed through blood or neutral solutions of pure oxyhemoglobin, 
the solution assumes a green colour in thin, and a red colour in thick layers, 
and becomes turbid. These solutions are characterised by the presence of two 
absorption-bands in the red, one on the red side of, but quite close to, C; the 
other is about midway between C and D, the two bands being united together 
by a shadow. 

It appears to me that there is not the slightest ground for believing 
that the phenomena above described are due to a definite body,—‘‘ sulpho- 


1 “Ueber Cyanhimatin,” Vriljschr. f. gerichlt. u. off. Med., Berlin, Supp. Bd. vi. 
S. 9-35. I only know this paper from the abstract by Andreasch in Jahresb. wt. d. Fortschr. 
d. Thier-Chem., Wiesbaden, 1883, Bd. xxiii. S. 620. 

2 «Ueber Kohlenoxyd-Hamoglobin,” 1. Oxydation von CO-Hb zu Meth-Hb, Arch. f. 
Physiol., Leipzig, 1880, S. 227-240. 

3 Centralbl. f. d. med. Wissensch., Berlin, 1868, No. 28; ‘‘ Ueber die Kinwirkung 
des Schwefelwasserstoffs auf d. Blutfarbstoff,’ Med.-chem. Untersuch., Berlin, 8. 651 ; 
Araki, “Schwefelmethemoglobin,” Zéschr. f. physiol. Chem., Strassburg, 1890, Bd. xi. 8. 
412-416. 


250 HEMOGLOBIN. 


methemoglobin”; they are almost certainly caused by a mixture of de- 
composition products of oxyhemoglobin, brought about by the action of H,S 
upon it. 


Hamatin (C,,H,;N,FeO,;, Hoppe-Seyler); (C3,H,)N,FeO;, Nencki 
and Sieber). 


As has been already stated, hematin is the colourmg matter 
which results from the decomposition of oxyhemoglobin by acids and 
alkalies. In acid and alkaline solutions the body is characterised by 
certain spectroscopic appearances, and especially by yielding, wnder 
suitable conditions, when treated with reducing agents, a body possessing 
the optical characters, when examined with the spectroscope, which 
were originally described by Stokes as those of “ reduced hematin,’ now 
known as “hemochromogen” (Hoppe-Seyler). 

Mode of preparation.—As we are now in possession of an easy and in 
all respects admirable method of preparing, in a state of great purity, the 
erystalline hydrochlorate of hematin or “hemin” (see p. 252), the latter 
body should invariably be employed in the preparation of pure hematin. 

Pure crystallised heemin (prepared by Schalfijew’s process) is dissolved 
ina highly dilute solution of potassium hydrate, and the alkaline solution 
is precipitated by means of dilute hydrochloric acid. The flocculent- 
brown precipitate is washed with hot distilled water until the washings 
give no turbidity with silver nitrate. The hematin thus precipitated is 
first dried at the temperature of 100°, and then at 115°, or even higher. 

Physical and chemical properties—Hematin has not hitherto been 
crystallised. In the condition of utmost purity it possesses a bluish-black 
colour, and a very pronounced metallic lustre. When finely powdered it 
appears as a dark brown powder, which is distinctly pleochromatie. 

It is insoluble in water, alcohol, ether, and chloroform, but slightly 
soluble in glacial acetic acid; also in acidulated alcohol, but absolutely 
insoluble in aqueous solutions of acids. It is very readily soluble in all, 
even highly dilute, alkaline solutions. 

Hematin forms a crystalline compound with hydrochloric acid 
(hematin hydrochloride, or hemin), which, because of its importance, 
will be separately described, and also others with hydrochloric and 
hydrobromie acids. 

It combines with potassium and sodium, as well as with calcium, 
barium, and other metals. The calcium and barium compounds are 
obtained by precipitating ammoniacal solutions of hematin by means 
of solutions of calcium or barium chloride, but they have not been yet 
obtained in a state of purity, and have not been analysed. 

Hematin may be strongly heated to 180° C. without undergoing 
decomposition. When heated further it is carbonised without previously 
melting or taking fire, and liberates hydrocyanic acid, leaving a 
residue of pure oxide of iron, which amounts to 12°6 per cent. of 
the hematin incinerated. 

When boiled with concentrated potassium hydrate, hematin under- 
goes no perceptible change; when fused with caustic potash, 1t is very 
slowly decomposed, and evolves ammonia. It is only attacked by 


1M. C. Husson, Compt. rend. Acad. d. sc., Paris, tome lxxxi. p. 477 ; V. D. Harris, 
Journ. Physiol., Cambridge and London, 1885, vol. v. p. 209; D. Axenfield, Centralbl. 
f. d. med. Wissensch., Berlin, 1885, No. 47. 


HAEMATIN. 251 


concentrated hydrochloric acid, at a temperature above 150° C. Con- 
centrated sulphuric acid dissolves it, without any gas being evolved, 
giving rise to a dark red solution, from which water precipitates the 
substance known as “hematoporphyrin” (see p. 258), which, as it 
contains no iron, has been sometimes spoken of as iron-free hematin. 
This body is soluble in alkaline solutions, and both its acids and 
alkaline solutions exhibit very characteristic absorption-spectra. 

Alkaline solutions of hematin in thick layers, when examined by 
transmitted light, appear red, whilst thin layers appear of an olive- 
green colour. Acid solutions, whatever the thickness of the stratum 
examined, always appear of a brown colour. 

When the spectrum of light transmitted through alkaline and acid 
solutions of hematin is examined by the photographic as well as by the 
direct method, it is seen that the last rays of the spectrum to be 
absorbed are the red rays up to B; that the solutions are characterised 
by a defined absorption-band between C and D, which is shifted towards 
D in the ease of the alkaline, towards C in the case of the acid solutions ; 
that alkaline solutions, even when extremely diluted, effect a general 
absorption of the whole ultra-violet, violet, etc., rays; that acid solutions, 
even when very highly diluted, whilst not exerting a general absorption 
of the ultra-violet, exhibit an absorption-band at the junction of the 
extreme violet and the ultra-violet, properly so called. 

The absorption-bands in the visible spectrum of both alkaline and 
acid solutions of hematin are shown in Plate II., Spectra 2, 4, and 6. 
The alkaline solutions exhibit one absorption-band between C and D, of 
which the more refrangible border adjoins D, whilst acid solutions exhibit 
an absorption-band also between C and D, of which the less refrangible 
border adjoins C, though the position of the band is somewhat in- 
fluenced by the particular acid which has been employed. Attention 
is directed to the fact that the band between C and D in the spectrum 
of methemoglobin differs in position from the band in the spectrum 
of acid as well as from that of alkaline hematin. Whilst the absorption- 
band of the former is close to C and that of the latter close to D, the 
band of methemoglobin, in acid solutions, is separated by a marked 
interval both from C and D, though it is closer to the former than to 
the latter. 

Alkaline solutions of hematin im the presence of certain foreign 
matters, when treated with reducing agents, exhibit a spectrum which 
is apparently identical with that which will be described under “ Heemo- 
chromogen,” and which was first described by Stokes as the spectrum of 
reduced hematin. The band in the red disappears, and two characteristic 
bands appear in the green (Plate IL, Spectrum 3). On now shaking 
the reduced liquid with air, the two bands first referred to disappear, 
and are replaced by the original hematin band. 


This experiment would appear to show that hematin is but oxidised hemo- 
chromogen, a conclusion which is false, and which is an illustration of the 
mistakes into which observers may be led who conclude as to the identity of 
two colouring matters from the identity of prominent absorption-bands in their 
spectra. 

A strong proof that oxidised hemochromogen is not identical with hematin 
is derived from my own observations on the absorption of the extreme violet and 
ultra-violet. Whilst hematin possesses even in solutions of great dilution the 
power of absorbing the whole of the ultra-violet, the violet and even the blue 


252 HAEMOGLOBIN. 


rays of the solar spectrum, oxidised hemochromogen is, in solutions of much 
greater concentration, remarkably transparent for the ultra-violet. 

Hoppe-Seyler made the observation that perfectly pure solutions of hematin 
are quite unaffected by reducing agents, but that the addition of certain foreign 
matters (e.g. albumin) renders reduction possible. I can, from my own re- 
peated observations, emphatically confirm this fact. 

It has been stated above that diluted blood and solutions of oxyhemoglobin 
treated with acids exhibit a band in the red between C and D (of which the 
centre is approximately situated at A 640), though it varies somewhat with the 
nature of the acid which has effected the decomposition. If, however, blood 
be treated with glacial acetic acid, and the mixture at once shaken with ether, 
the latter subsequently separates, holding so much of an acid compound of 
hematin in solution as to possess a deep red colour. This ethereal solution, 
in addition to the characteristic band of acid hematin, exhibits three other 
bands whose positions and relative intensities are indicated in Plate II., 
Spectrum 6. 


Hematin hydrochloride (sy. heemin).—When a minute drop of 
blood on a glass slide is mixed with a drop or two of glacial acetic 
acid, and the mixture is boiled over a tiny flame, and then allowed 
to evaporate, the residue is found on microscopic examination to 
contain innumerable reddish-brown prismatic crystals, which were 
formerly constantly referred to as Teichmann’s! crystals (after their 
discoverer). Such crystals may be obtained from any old blood stain 
on cloth, linen, wood, metal, etc. The stained tissue or the scrapings 
of the stain are heated, as above, with glacial acetic acid. It is neces- 
sary, however, in the case of stains which may have been subjected 
to the action of water, to add a minute crystal of sodium chloride 
to the glacial acetic acid before boiling. Hoppe-Seyler? subsequently 
discovered methods of obtaining Teichmann’s crystals in quantities, 
which enabled him to examine their physical properties with some 
degree of completeness and to analyse them, and he was able to show 
that hemin is a compound of hematin and hydrochloric acid, to which, 
as a result of his more recent researches, he ascribed the empirical 
formula C,,H,;N,FeO,HCl. Nencki and Sieber,? on the other hand, 
assigned to hemin the formula C.,H,,N,FeO,HCl, corresponding to the 
formula C.,H.,N,FeO,, which they assign to hematin. 


Method of preparing hwemin in bulk.—A method for preparing hemin in 
bulk was, as has been said, first devised by Hoppe-Seyler, and other methods 
were described by Nencki and Sieber. These methods demand the ex- 
penditure of much time, labour, and patience; and none of them, as | know 
from my own abundant personal experience, yield a product which can 
compare in the absolute uniformity of its crystallisation and the complete 
absence of all amorphous matter with the one described by Schalfijew, which 
is as follows :— 

One volume of defibrinated and strained blood is added to four volumes of 
glacial acetic acid, previously heated to 80°C. As soon as the temperature has 
fallen to 55°-60°, the liquid is again heated to 80°C. On cooling, crystals at 
once ey and can be seen floating in the liquid, presenting a charac- 


1 Zischr. f. rat. Med., 1853, Bd. iii. S. 375, and Bd. viii. S. 141. 

2 Virchow’s Archiv, 1864, Bd. xxix. S. 597-600; ‘‘Das Hamin,” Med.-chem. Unter- 
such., Berlin, 8. 379-385. 

3 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1884, Bd. xviii. S. 401 ; 1886, Bd. xxi. 
S. 325 ; 1888, Bd. xxiv. S. 430. 


HAMATIN HYDROCHLORIDE. 253 


teristic silky lustre and a dark blue colour. The crystals are allowed to settle 
for at least twelve hours, and the clear dark brown mother-liquid is syphoned 
off. The blue sediment, if care was taken to avoid the presence of any 
blood clots in the defibrinated blood used in the preparation, is found on 
microscopic examination to be entirely composed of crystals of hemin. It 
is repeatedly washed by decantation with water; then thrown on a filter, 
and, after renewed washing with distilled water, it is subjected to long-con- 
tinued washing with spirit and ultimately with absolute alcohol. This washing 
with alcohol must be continued so long as the alcohol assumes a brown colour, 
and is a very long process. The blue mass remaining on the filter is ultimately 
washed with ether and alcohol, and in the first instance is allowed to dry by 
exposure to the air, and afterwards by heating to 115° C.! 

It was stated by Schalfijew that by his process 5 grms. of pure hemin can 
be obtained from 1 litre of defibrinated blood. This yield, which would be 
approximately equivalent to the theoretical yield, on the assumption that the 
blood contains in the mean 12 per cent. of hemoglobin, is from my own experi- 
ence never realised, 1 litre of blood yielding on the average 3°5 germs. of 
pure hemin. 


Physical and chemical properties—Whilst presenting in mass a blue 
colour, and exhibiting, when floating in a liquid, a silky lustre, on micro- 
scopic examination hzemin crystals appear dark brown elongated rhombic 
plates and prisms belonging to the triclinic system. They are arranged 
singly or in groups. They are strongly doubly-refracting. They are 
quite insoluble in water, alcohol, ether, or chloroform. 

When pure uniformly crystallised hemin is boiled in pure glacial 
acetic acid, the latter dissolves an appreciable quantity, assuming a dark 
brownish-red colour. From this solution the hzemin is in great part de- 
posited, on cooling, in perfect crystals, without any admixture with 
amorphous substances. I find, however, that if the process of re-crystal- 
lisation be repeated, the substance deposited on cooling consists of 
heemin crystals mixed with some amorphous colouring matter. 

Hemin is very easily soluble in highly dilute solutions of the caustic 
alkalies and their carbonates; from these solutions hematin is pre- 
cipitated on the addition of an acid. If nitric acid be used as the 
precipitant, the chlorine which had originally been combined with the 
hematin, and which is now present in the filtrate as an alkaline 
chloride, can be precipitated by silver nitrate. 

When hemin crystals are heated, they remain unchanged up to 
about 200° C.; more strongly heated, they glow and leave an ash com- 
posed of pure iron oxide. When pure hemin is intimately mixed, as by 
pounding, with pure concentrated sulphuric acid, hydrochloric acid is 
liberated. 


Nencki and Sieber, who employed amyl alcohol in the preparation of 
hemin, found that when prepared in this way the crystals contained amyl 
alcohol, and that their composition corresponded to the formula ((ORs1EEAS y, 
FeO,.HCl),C,H,.OH. 

The existence of a definite compound of hemin and amyl alcohol is, 
however, doubted by Hoppe-Seyler.? 


1M. Schalfijew. I have not seen the original paper in the Journ. russk. fiz.-chim. 
Obsh., St. Petersburg, 1885, S. 30-37. See abstracts in Ber. d. deutsch. chem. Gesellsch., 
Berlin, 1885, Bd. xviii. (Referat Bd.), S. 232-233 ; also in Jahresb. ii. d. Fortschr. d. Thier- 
Chem., Wiesbaden, 1885, Bd. xv. S. 138. 

*“Ueber Blutfarbstoffe und ihre Zersetzungsproducte,” Zischr. f. physiol. Chem., 
Strassburg, 1882, Bd. x. 8. 331. 


SOLERO-SPECTRUM. 


HaMIN. 


254 HEMOGLOBIN. 


The compounds of hematin with acids, e.g. hematin-hydrochloride, 
present, even in solutions of great dilution (1 : 25,000-1 : 50,000), an 
intense absorption-band, which encroaches more and more on the 
ultra-violet, as the strength of the solution increases. In a solution con- 
taining one part of crystallised hematin hydrochloride in 20,000 parts 
of elaci al acetic acid, the band extends between h and M, the most 
intense absor ption between and L. The less refrangible border of this 
band is sharply defined, whilst the more refrangible border is less 
definite. As the solution is diluted the band becomes narrower, 
through less and less of the ultra-violet being absorbed. In highly dilute 
solutions the band which is still intense absorbs both H and K.! 

The acid compounds of hematin exhibit, therefore, an absorption- 
band, which is exactly on the boundary of the ultra-violet proper, and 
whic h extends further and further into the ultra-violet as the con- 
centration of the solution increases. 


G EKG eM N O 


Fic. 37.—The photographic spectrum of hemin. 


HAMOCHROMOGEN (Syn. “ REDUCED HA:MATIN ”). 


It has already been explained that Hoppe-Seyler employed the 
name hemochromogen to denote the very remarkable body which he 
was the first to study with care, and which results from the decomposi- 
tion of reduced hemoglobin, in the absence of all oxygen, by acids, and 
especially by alkahes, and of which the solutions present absorption- 
bands in the visible spectrum, which are identical with those of the 
reduced hematin of Stokes. 

The latter name had been applied by Stokes to the chemical 
substance assumed to be the cause of the characteristic absorption- 
spectra which are exhibited by solutions of the blood-colouring matter, 
and likewise by impure solutions of hematin when subjected to the 
action of reducing agents. It now remains to describe the methods of 
propane solutions of hemochromogen, the body itself and its properties 
(so far as these are known to us), its combinations, and especially to 
refer to the views which Hoppe-Seyler advanced and held, in reference 


1 Gamgee, Proc, Roy. Soc. London, 1896, vol. lix. p. 276. 


H4&EMOCHROMOGEN. 255 


to the relations of hemochromogen to hemoglobin, and the part which 
it plays in relation to the optical properties of, and the chemical affinities 
for gases manifested by, the complex molecule of hemoglobin. 

Methods of preparing solutions containing hemochromogen by the direct 
decomposition of hemoglobin—Without referring to a more complicated 
and in some respects more satisfactory method of decomposing hzemo- 
globin in the absence of oxygen,! the following very simple method, 
which, like the first, we owe to Hoppe-Seyler,? will be described. 

A solution of oxyhemoglobin is placed in a glass tube, and then a 
smaller glass tube containing a solution of sodium or potassium hydrate, 
or, if desired, of tartaric or phosphoric acid, is introduced into the larger 
tube, the open end of which is then drawn out and sealed in the blow- 
pipe flame. The apparatus thus prepared is then subjected to gentle 
heat, taking care not to incline the tubes so as to cause their contents 
to mix. 

The oxyhemoglobin contained in the larger, outer tube first becomes 
reduced, and thereafter the oxygen contained in the air of the tube is 
absorbed by the hemoglobin. When many days have elapsed, and the 
whole of the hemoglobin is again reduced, the tubes are inverted and 
their contents mixed, when the formation of hemochromogen may be 
followed by the changes in colour and in the spectrum, which the 
colouring matter undergoes. 

Physical and chemical properties—When acted upon by dilute solu- 
tions of the caustic alkalies, hemochromogen gives rise to a beautiful 
cherry-red solution, which, when sufficiently diluted, exhibits two 
absorption-bands apparently identical with those of Stokes’ reduced 
heematin, which have already been referred to. 

The visible spectrum of solutions of hemochromogen in alkaline 
solutions is distinguished from all others by the extraordinary intensity 
and sharpness of the absorption-band nearest to D. The second ab- 
sorption-band, which is very much less intense, has less sharply-defined 
borders. The solution, even when concentrated, absorbs very little of 
the red. 

The following are measurements of the position of the absorption- 
bands in the visible spectrum by Hoppe-Seyler and myself :— 


Gamgee’s measurements? (1878) A 567-547 d 532-518 
Hoppe-Seyler’s 4 # (1889) A 565-547 527-514 


My study of the photographic spectrum of hemochromogen has led 
to the following results :°—Solutions, even of very great dilution, exhibit 
an absorption-band between i and gy. This band has the same position 
as the band of CO-hzemoglobin, but is much more intense. With one 
part of hemochromogen in 25,000 parts of water, a stratum 10 mm. thick 
being examined, an intense absorption-band occupies the region between 
24100 and 4430°0. From the examination of solutions of various strengths 
it results that the mean ray absorbed corresponds to about A 420°0. 

By heating to 110°C. a solution of hemochromogen mixed with 
a sufficiently concentrated solution of sodium hydrate, hemochromogen 

1 Hoppe-Seyler, Med.-chem. Untersuch., Berlin, S. 540 and 541; and Gamgee’s 
‘Physiological Chemistry,” vol. i. pp. 118 and 119. 

2 ««Physiol. Chem.,” 1878, S. 390. 

3 < Physiological Chemistry,” 1880, vol. i. p. 111. 


4 Ztschr. f. physiol. Chem., Strassburg, 1889, Bd. xiii. S. 496. 
5 Gamgee, Proc. Roy. Soc. London, 1896, vol. lix. p. 276. 


256 HEMOGLOBIN. 
sae as a violet-grey powdery precipitate, which dissolves again in 

the liquid from which it had se parated, as soon as this cools. It 1s quite 
erroneous to state, as is asserted in all text-books,! that Hoppe-Seyler 
succeeded in separating hemochromogen in a crysté line condition. He 
only succeeded (at most) in obtaining crystals of the CO- Rey 
and concluded that he mochromogen itself must be a er ystalline body, but 
he never even asserted that he had actu: ally obtained the crystals, and a 
promise made in 18892 to describe the assumed crystalline hemo- 
chromogen, though implying that he had already obtained the body in 
this condition, was never fulfilled. Moreover, in the last systematic 
account of hemochromogen which he published in 1893, Hoppe-Seyler 2 
does not refer to its being crystalline, but, on the contrary, speaks of it 
(as he had done in 1889) as separating in the form of a violet t-grey 
powdery precipitate. 

G Es iN O 


SPECTRUM OF 


7. 
= 
= 


Fig. 38.—The photographic spectrum of oxygenized hemochromogen and of 
hi emochromogen. 


Acids, even when very dilute, lead in the first instance to the forma- 
tion of hemochromogen from reduced hemoglobin, in the absence of 
oxygen; they, however , decompose a part of the hemochromogen with 
great rapidity, removing its iron and giving rise to heematoporphyrin. 
This explains, according to Jiderholm,‘ the complex (four -banded) nature 
of the spectrum of hemochromogen, as at first described by Hoppe- 
Seyler,> when prepared by the action of acids on hemoglobin. 


* Hammarsten, ‘‘ Lehrbuch d. phys. Chem.,” Dritte Auflage, 1895, S. 122 ; Neumeister, 
**Tehrbuch der physiol. Chem., ete.,” 1895, Bad. ii. S. 154; Halliburton, ‘‘ A Text-Book 
of Phys. Chemistry,” 1891, p. 290; Sheridan Lea, ‘‘The Chemical Basis of the Animal 


Body,” Appendix to Foster’s ‘‘ Physiology,” 1892, p. 232. 
~ Hoppe-Seyler, Ztschr. f. physiol. Chem., Strassburg, 1889, Bd. xiti. S. 495. 
° Hoppe-Seyler und Thierfelder, ‘‘Handbuch d. phys. u. path. Chem. Analyse,” 


Berlin, 1893, S. 214, 215 (‘‘ Hi imochromogen ’ °). 
4 See At t by Hammarsten in Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 
874, Bd. Ss. 102. 
> Med. feo: Untersuch., Berlin, 8. 542. In his later descriptions of the spectrum of 
acid solutions of hz smochromogen no mention is made of four bands. 


HEMOCHROMOGEN. 257 


When subjected to the action of such reducing agents as tin and 
hydrochloric acid, heemochromogen gives rise to coloured products, which 
are obviously nearly related to, though not identical with, such bodies as 
the so-called urobilins. 

It was stated that when blood saturated with CO, or a concentrated 
solution of CO-hzemoglobin, is treated with a concentrated solution of 
sodium hydrate, a bright red precipitate separates. Jdaderholm stated 
that this precipitate consisted of a compound of CO with hematin, and 
could be prepared directly by the action of the gas on a solution of 
reduced hematin; he further asserted that the visible absorption- 
spectrum of the CO-hzmatin closely resembled that of CO-hemoglobin, 
the bands occupying the same position; though he described them as 
being less intense in the hematin compound, and as differing from the 
CO-hemoglobin compound in the fact that the two bands « and #6 
exhibit equal intensities. 

By causing an alkaline hydrate to act upon CO-hemoglobin in the 
absence of oxygen (method with double tubes previously described), and 
heating to 100° C., Hoppe-Seyler separated the body which Jiader- 
holm had described as CO- hematin, but which appears really to be 
CO-hzemochromogen. Like hemochromogen itself, its CO-compound, 
which has been deposited at 100° C., dissolves again when 
the liquid from which it separates cools. The CO-compound of 
hemochromogen is described by Hoppe-Seyler as a crystalline body, 
though none of its physical characters have been subjected to even a 
superficial examination. The visible spectrum of its solution is, accord- 
ing to Hoppe-Seyler, absolutely undistinguishable from that of CO- 
hemoglobin. 

The most interesting and weighty observation made by Hoppe- 
Seyler on this subject was, however, that concerning the volume of CO 
which combines with heemochromogen to form its CO-combination. He 
found that the same volume of CO combines with hemochromogen as 
would be required to convert an equivalent weight of reduced hemo- 
globin into the CO-compound. This unquestionably interesting ob- 
servation, taken in connection with the fact that crystals form under 
certain circumstances in solutions which contain CO-hemochromogen 
(there is no absolute proof that the crystals represent this substance), 
led Hoppe-Seyler to form certain hypotheses of extraordinary boldness, 
for which the experimental bases are as yet altogether wanting, but 
which have been accepted with misplaced confidence; these hypotheses 
he looked upon as legitimate conclusions from his own experiments, and 
formulated as follows :— 

“We are justified in concluding that in crystallised CO- hemoglobin, 
as well as in the colouring matter of the blood corpuscles, there is 
present a particular group ‘of atoms which combines with and retains 
carbonic oxide, which is characterised by the special manner in which it 
absorbs light, and which, after separation from the albuminous residues, 
passes unchanged into CO-hemochromogen. 

“Without possibility of doubt, this group of atoms is identical with 
the one which, in the arterial blood- colouring matter,! and in crystallised 
oxyhemoglobin, holds two atoms of oxygen in combination, i in the place 
of a molecule of CO. 

“The oxyhzemoglobins, the heemoglobins, and the CO-hemoglobins, as 

1 Reference is here made to the hypothetical ‘‘arterin.” 
VOL. 1.—17 


258 HEMOGLOBIN. 


well as the colouring matters of the red-blood corpuscles, all contain 
hemochromogen, and this body can be obtained from them all by a 
process of simple decomposition, even in the crystalline condition, and 
almost in theoretical proportions.” * 

In other words, Hoppe-Seyler announced that, from his experiments 
it might be concluded that hemochromogen represented an iron-con- 
taining coloured radical, which, by inking itself to an albuminous residue 
or albuminous residues, forms hemoglobin, and that hemochromogen in 
the latter body combining with a molecule of oxygen forms oxyhemo- 
globin; with a molecule of carbonic oxide, carbonic-oxide hemoglobin, 
etc.—these substances containing oxyhemochromogen and CO- haemo- 
chromogen respectively. 

Not “only are the facts wanting which would be needed in order to 
prove this hypothesis, but there are many others which appear to me 
to indicate that whilst, when once formed, hemochromogen, as indeed 
hematin, includes the specific atomic group upon which “the character- 
istic optical and physico-physiological properties of the blood-colouring 
matter depend, probably hemochromogen does not exist preformed in 
heemoglobin and its compounds. I trust shortly to throw more light 
on this question. 


Linossier 2 described compounds of hematin and reduced hematin with 
nitric oxide as well as with carbonic oxide. On repeating his experiments, 
I convinced myself that (as had been shown by Jaderholm and by Hoppe- 
Seyler in the case of CO) NO exerts no action on hematin, but appears to form 
a compound with hemochromogen, which is possessed, as Linossier describes, 
of a fine red colour, and exhibits two absorption-bands between D and E, 
similar to those of oxyhemoglobin. This NO-hemochromogen awaits a careful 
examination. 

Hoppe-Seyler has speculated in reference to the condition in which the 
iron exists in hemochromogen and hematin respectively, and has emitted the 
opinion that the iron in hemochromogen is present in a ferrous and in hematin 
in a ferric condition, but the grounds for an opinion do not actually exist.® 


HA:MATOPORPHYRIN. 


Methods of preparation. — When either hematin or hemin is 
thoroughly mixed with concentrated sulphurie acid, it dissolves, and 
by filtering through asbestos a clear and beautiful purple-red solution 
is obtained. When this solution is poured into a large quantity of 
water, the greater part of the dissolved colouring matter is precipitated 
in the form of a brown flocculent precipitate, the quantity of which 
increases if alkalies be added so as to neutralise the acid. This colour- 
ing matter is impure hematoporphyrin. In this operation the acid 
separates the whole of the iron from the hematin, and it is found in 
solution in the state of a ferrous salt. In the process of decomposition 
of hematin by sulphuric acid there is no evolution of hydrogen gas. 

From hematin and hemin hematoporphyrin can also be obtained— 
(1) by the action of strong HCl in sealed tubes heated to 130° C. 


: Hoppe- Seyler, Zischr. f. physiol. Chem., Strassburg, Bd. xiii. S. 492 and 493. 
2 “Sur une combinaison de I’hématine avec le bioxyde d’azote,”” Compt. rend. Acad. d. 
, Paris, tome civ. p. 1296. 

& «For te discussion of the question, see Hoppe-Seyler, Med.-chem. Untersuch., Berlin, 
546-55 


HA#MATOPORPH YRIN. 259 


(Hoppe-Seyler); (2) by the action of acetic acid saturated with HBr, 
aided by heat (Ne ncki and Sieber). 

Hzemochromogen is, in the absence of oxygen, converted even by the 
weakest acids into hematoporphyrin, the iron being found in the 
solution as the ferrous salt of the acid employed. Although occurring 
more slowly, the decomposition of CO-hzemochromogen by acids also 
yields hematoporphyrin. 

According to Hoppe-Seyler, the composition of hzematoporphyrin is 
represented by the formula C. an .N,O 

According to Nencki and Sieber, who have made the most complete 
inve estigation of this body, it has the composition C,,.H,.N,O., and they 
explain its origin from hematin by the following equation, in which 
they adopt their own as distinguished from Hoppe-Seyler’s formula for 
hematin— 

C,,H.)N,FeO,+3H,0 =2(C,,H,,N,0;1Fe) 


(hematin) 


According to Nencki and Sieber, hematoporphyrin is isomeric with 
bilirubin. 
G h EER ieee Nig ©: 


Fic. 39.—The photographic spectrum of hematoporphyrin. 


Physical and chemical properties—Hematoporphyrin forms beauti- 
ful crystalline compounds with Na and with HCl. 

It is insoluble in pure distilled water, shghtly soluble in dilute acids, 
more soluble in strong acids, and re eadily soluble in alkaline solutions, 
weak and strong. It is also readily soluble in acid and alkaline alcohol. 

Solutions of hematoporphyrin in acidulated alcohol have a beautiful 
purple colour, and assume a bluish violet tint when the solution is made 
very strongly acid. Alkaline solutions are of a fine red, but in the 
presence of a great excess of alkali exhibit a violet tint. Solutions of 
hematoporphyrin, even if extraordinarily dilute, exhibit a magnificent 
red fluorescence, which strangely enough is not referred to in text-books, 
though it seems to me to be their most remarkable characteristic. 

An alcoholic solution of hematoporphyrin, acidulated with hydro- 


260 HAMOGLOBIN. 


chloric or sulphuric acids, exhibits in the visible spectrum two absorption- 
bands, of which one, which is the narrower and the weaker, is situated 
between C and D and immediately adjoms D. The second, which is 
much more intense, more sharply defined and broader, les nearly mid- 
way between D and E; but nearer the former than the latter. 

Alkaline solutions exhibit in the visible spectrum four absorption- 
bands, to wit, a weak band midway between C and D, an equally 
weak band between D and E, but nearer to the former, a more strongly 
marked band nearer to E, and lastly a fourth band, darkest of all, which 
occupies four-fifths of the interval between B and F. 

The spectra of acid and alkaline hematoporphyrin are exhibited in 
Fig. 57. 

A study of the DPC er pais spectrum of hematoporphyrin has 
given me the following results: '—Acid solutions of hematoporphyrin, 
so dilute as to appear colourless (though presenting, if examined in a 
dark room by means of a beam of sunlight reflected from the mirror of 
the heliostat, the marked red fluorescence previously referred to), exhibit 
an intense absorption-band between 4 and H. If the solution be 
slightly more concentrated, K is absorbed, and with increasing con- 
centration of the solution the absorption of the ultra-violet extends 
more and more. 

Alkaline solutions of hematoporphyrin absorb the same spectral 
region, but the intensity of the absorption is greater. 


Hematoporphyrin, as MacMunn has shown, occurs as a colouring matter 
in the integument of some invertebrates and in the egg-shells” of certain 
birds.2 In small quantities it occurs in the normal urine (Arch. Garrod), 
and in larger quantities in certain toxic conditions, especially in one of the 
forms of chronic sulphonal poisoning. 


HA:MATOIDIN. 


This name was applied by Virchow to a substance which occurs in 
the form of orange-coloured microscopic erystals (rhombic plates) in old 
extravasations of blood, as in apoplectic clots, and which is certainly de- 
rived from hemoglobin. These crystals are, according to most observers, 
identical in form with those of bilirubin, and when treated with fuming 
nitric acid exhibit the same colour reaction (Gmelin’s reaction). 
Heematoidin, like bilirubin, exhibits no definite absorption-band in its 
spectrum, but effects a general absorption of the ultra-violet, violet, and 
blue rays of the spectrum. Opinions were long divided on the question 
of the identity or non-identity of hematoidin and bilirubin, but they 
are now generally regarded as identical. 


Certain other substances (of which the chemical history is very imperfect), 
which can be directly obtained by the action of reagents on the blood-colour- 
ing matter, and certain pigments occurring in the organism, and which, on 
erounds more or less satisfactory, have been held to be derived from it like- 
wise, will be considered in the account of the chemistry of the urine as well 
as in that of the chemical processes occurring within the alimentary canal. 


1 Proc. Roy. Soc. London, 1896, vol. lix. p. 279. 
*MacMunn, Journ. Physiol., Cambridge and London, 1885, vol. vii. p. 240; vol. 
Vili. p. 384. 


A GENERAL ACCOUNT OF THE PROCESSES OF 
DIFFUSION, OSMOSIS, AND FILTRATION. 


By E. WaymoutH REID. 


ConTENTs : — Diffusion, p. 261—Osmosis, p. 264—Filtration, p. 280. 


DIFFUSION. 


By current hypothesis the molecules of a liquid are considered to be in 
constant motion, so that if two liquids, miscible without chemical inter- 
action, are placed in contact, a mutual interpenetration, without the 
action of any external force, takes place; or, in other words, a diffusion 
of the molecules of one among those of the other, and vice versd, occurs, 
the process tending to continue until in the final state a homogeneous 
mixture of the two exists. In physiological problems we deal with the 
diffusion of substances in dilute aqueous solution, and it must at once 
be noted that the condition of the molecules of a substance in dilute 
aqueous solution is probably different in the case of different substances, 
and by no means necessarily the same as that of the undissolved 
substance ; that, in fact, the solvent and dissolved substance in many 
cases interact, with a resultant alteration of physico-chemical pro- 
perties. 

In the case of substances acting as electrolytes in aqueous solution, 
it is beheved that dissociation into the ions takes place to a greater or 
less extent of the total number of molecules, according to the degree of 
dilution.!. There will thus be at lower degrees of dilution a mixture of 
molecules, active as regards electrolytic conduction and chemical action, 
and inactive molecules, the latter tending to become active by ionic 
dissociation as dilution is increased, so that at infinite dilution only 
active molecules exist in the solution. Zhe coefficient of activity will be 
the number expressing the ratio of active molecules to the total of 
active plus inactive, and is unity at infinite dilution. The electrical 
conductivity of a solution of an electrolyte is dependent on the velocity 
of migration of its ions,’ so that the ratio of the molecular conductivity * 
of a solution of an electrolyte at given dilution, to the limiting value 


1 Arrhenius, Bijhang. till k. Svens. Vet.-Akad., Stockholm, 1884, Bd. viii., Nos. 
13 and 14; Ztschr. f. physikal. Chem., Leipzig, 1887, Bd. i. S. 631. 

2 Kohlrausch, Ann. d. Phys. u. Chem., Leipzig, 1879, Bd. vi. S. 1, 145; 1885, Bd. xxvi. 
S. 161. 

3 The molecular conductivity is the ratio of the conductivity to the molecular concen- 
tration of the solution, the latter being the ratio of grammes per litre to the molecular 
weight in grammes, 


262 DIFFUSION, OSMOSIS, AND FILTRATION. 


which this approaches on increasing dilution, is a measure of the 
coefticient of activity of the solution. According to this view, then, a 
very dilute solution of sodium chloride consists of positively-charged 
sodium and negatively-charged chlorine ions moving amongst the water 
molecules, but unable to part company by virtue of their charges of 
opposite sign, and only separable by the application of energy from 
without (electrolysis). Other substances which do not conduct elec- 
tricity in aqueous solution are believed to be in a simpler state of 
solution, the molecules moving among those of the solvent not being 
known to be in a different condition to those of the undissolved sub- 
stance, but simply capable of freer motion. 

It is further probable that in the case of certain non-electrolytes in 
solution, instead of single molecules we deal with aggregates of mole- 
cules, and such substances are said to be in colloidal solution (26dA«, 
glue). As instances of organic substances the aqueous solutions of 
which are colloidal, may be mentioned albumin, gum-arabic, starch, 
heemoglobin.? 

It must at once appear likely that the ease with which the 
“molecules” of different substances can move among those of the 
solvent in a solution is different in the case of different substances, 7.e. 
that the power of diffusibility must be very variable. 

Graham ? gives the following table :-— 


Equal weights had diffused to the same extent in the following times :— 


Hydrochloric acid . 1 Magnesium sulphate . 7 
Sodium chloride . Satoe Albumin . ; ; ae 
Cane-sugar : sh Caramel. - we 


Substances in solution tend to diffuse from places of higher to those 
of lower concentration, and in the law of Fick? it is stated that the 
quantity of dissolved substance so diffusing is proportional to the rate 
of fall in concentration. 

Thus, if a is the quantity of substance passing section q of a diffusion 
cylinder in time z, when at z the concentration in the section is ¢, and at 
x+dz is e+de; then— 

h de 
a4 =— Kgz aie 


where & is a constant peculiar to the substance and known as the 
coefficient of diffusion. 
From the law of Fick, Stefan+ calculated for a special case the 


following formula :— 
=O, / 
T 


1 Picton and Linder (Journ. Chem. Soc., London, 1892, vol. Ixi. p. 148; 1895, vol. 
Ixvii. p. 63) have prepared solutions of arsenious sulphide of various ‘‘ grades.” Thus one 
may have («) aggregates visible by microscope ; (6) no visible aggregates, but the substance 
not diffusible; (y) the substance diffusible but not filterable; (3) the substance both 
diffusible and filterable, but the aggregates still large enough to scatter light. They 
consider that in matter in solution one can pass by grades from obvious suspension, to 
colloidal solution, to non-electrolytic crystallised solution, and so to the first grade of 
electrolytic solution. 

2 Phil. Trans., London, 1861, vol. cli. p. 183. 

3 Ann. d. Phys. wu. Chem., Leipzig, 1855, Bd. xciv. S. 59. 

4 Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1879, Bd. Ixxix. S. 161. 


DIFFUSION. 263 


where @ is the amount of substance, passing in time 2, through section gq, 
from an infinitely long cylinder of solution of concentration c, into 
another such cylinder of pure solvent. 

This formula was experimentally verified by Voigtlander! with 
eylinders of agar jelly, in which diffusion occurs as easily as in water.’ 
He further investigated the temperature coefficient («) for k, and found 
that it is not a linear function of the temperature, as stated by Weber,’ 
but stands in the following relation *:— 


K,=K, A+aty? 


In the case of an electrolyte in solution, the diffusion must be con- 
-sidered as that of the ions into which it is dissociated on passing into 
solution. The velocity of the separated ions may be very different, but 
since in solution by virtue of their opposite charges they cannot part, 
the more rapidly moving ion must be retarded by the more slowly 
moving, and the more slowly moving accelerated by its more active 
fellow. The diffusion of an electrolyte may also be accelerated by 
the presence in the liquid into which it is diffusing, of ions charged 
oppositely to those forming the more active partner in the diffusing 
substance. Thus hydrochloric acid diffuses faster mto a solution of 
sodium chloride than into water.’ As a rule, those electrolytes which 
are the best conductors, are the most diffusible in solution.’ The pre- 
sence of a substance that is not an electrolyte in the fluid into which 
diffusion is taking place may slow the diffusion of an electrolyte. 
Thus sodium chloride diffuses more slowly into sugar solution than 
into water, and the presence of ethyl alcohol also retards its diffusion.’ 
In the case of non-electrolytes in solution, diffusion must concern the 
“molecules” of the dissolved substance, and the “aggregates” of colloids 
will find their way with greater difficulty than the “molecules” of 
cerystalloids. 

No definite rule can be stated as regards the effect of concentration 
of the solution upon the rapidity of diffusion of the dissolved substance. 
With sodium chloride the coefficient of diffusion is practically unaltered 
by change in concentration of the solution. In the case of magnesium 
sulphate the coefficient falls with the concentration of solution, while 
with hydrochloric, nitric, and sulphuric acids the coefficient rises with 
the concentration.* 

The simultaneous diffusion of two salts, studied first by Graham, has 
been since more completely investigated by Marignac.’ In general the 
rapidity of diffusion of the more diffusible of a pair of salts diffusing 
simultaneously is found to be increased, that of the less diffusible 
diminished. 

In the following table the diffusions of five pairs of salts, separately 
and simultaneously, are contrasted. 

1 Ztschr. f. physikal. Chem., Leipzig, 1889, Bd. iii. S. 316. 

2 Graham, Ann. d. Chem., Leipzig, 1862, Bd. exxi. 8. 5, 29. 

3 Ann. d. Phys. u. Chem., Leipzig, 1879, Bd. vii. S. 536. 

4 For the values of z, which vary slightly with different substances, see Voigtlinder’s 
original paper, Joc. cit. 

5 Arrhenius, Zischr. f. physikal. Chem., Leipzig, 1892, Bd. x. S. 51. 

8 Long, Ann. d. Phys. u. Chem., Leipzig, 1880, Bd. ix. S. 613 ; Lenz, Mém. Acad. imp. 
d. sc. de St. Pétersbourg, 1882, tome vii. p. 30. 

7 Arrhenius, Joc. cit. 

8 Scheffer, Ztschr. f. physikal. Chem., Leipzig, 1888, Bd. ii. S. 390. 

9 Ann. de chim., Paris, 1874, Sér. 5, tome il. p. 546. 


264 DIFFUSION, OSMOSIS, AND FILTRATION. 


rv is the ratio of the diffusion coefficients of the two salts, with 
separate diffusions. 

7 is the ratio with simultaneous diffusions. 

R, the ratio of the amounts diffused of the same salt in separate 
and in simultaneous diffusion, ze. the alteration of the coefficient of 
diffusion produced by the presence of the other salt. 


Separate. | Simultaneous. 7 re pasion R. 
| 

fNaCl . roma! “5833 "6054 1 1 =5¢ 1°038 
Na SO gt Mh eer70 ‘2497 590 "352 “596 662 
(KCI. Send “8560 | 9276 1 1 Sot 1°083 
\ BaCl, . ; 8433 | -4424 DIZ "401 | ‘701 “814 
fNaCl . : 7142 7883 1 1 Sct 1°019 
(ieawls 2 Hees. | beep a Tbe "668° | "882 “921 

PESOS. PIL i raya5 *4378 1 1 a “901 
{Masd. . | 2028 | 1684 “382 "B45 903 "830 
fNa,SO, Sl, sotoe 3420 HI 1 coe 910 | 
Wiese 8 | 2097 || 1823" “588 502 -| 960 | 869 | 


} | 
} 7 


As arule, as seen in #&, the more diffusible salt is accelerated, the 
less diffusible delayed. In the two last pairs both members are delayed, 
but the less diffusible more markedly. 

In the body it is rare to find the conditions present for a free 
diffusion between the constituents of two solutions; a membrane, 
whether composed of cells or the surface layer of the protoplasm of 
a cell, as a rule intervenes, and obviously the permeability of the 
membrane affects the result. If pig’s bladder separates methyl alcohol 
and ether, the methyl alcohol diffuses into the ether, but if a caoutchoue 
membrane separates the two liquids, the ether diffuses into the alcohol.* 


OSMOSIS. 


The term osmosis is applied to diffusion taking place between two 
liquids separated by a membrane. 

The simplest case of this is that in which a solution of a substance 
is separated from the pure solvent by a membrane permeable by the 
solvent but impermeable by the dissolved substance. Such membranes 
were first prepared by Traube,? in the form of colloidal precipitates, 
such as tannate of gelatin and ferrocyanide of copper, but Pfeffer * 
was the first to thoroughly study the process of osmosis under such 
conditions. The name “semipermeable” has been given to such mem- 
branes, but it must be noted at once that this expression is seldom 
strictly accurate and must always be used relatively to some particular 
substance. Tamman* has pointed out that such membranes are by 
no means the “molecule sieves” that Traube imagined,’ and in experi- 
mental work the membrane must be chosen to suit the substance, or 
vice versd. Copper ferrocyanide forms one of the best of such mem- 
branes, and is nearly impermeable to cane sugar. 


? Raoult, Zéschr. f. phystkal. Chem., Leipzig, 1885, Bd. xvii. S. 735. 
® Arch. f. Anat. u. Physiol., Leipzig, 1867, 8. 87 and 129. 

* **Osmotische Untersuch.,” Leipzig, 1877. 

* Ztschr. f. physikal. Chem., Leipzig, 1892, Bd. x. S. 255. 

®° See also Walden, ibid., 1892, Bd. x. S. 699. 


OSMOSIS. 265 


In practice such membranes are formed in the interstices of an 
indifferent supporting structure, such as the pores of a porous battery 
pot (preferably previously soaked in gelatin), by placing one of the mem- 
branogens inside the pot, which is then lowered into a solution of the 
other, : so that the precipitate is formed within the structure of the 
earthenware where the two solutions come into contact. It is only by 
such an artifice that the membrane can be sufficiently supported to 
enable it to withstand the high pressure produced by the osmosis under 
the conditions." 

If, now, a battery pot with such a membrane in its pores be filled 
with a solution of sugar in water, hermetically sealed, and placed in 
a vessel of water, the water molecules will diffuse in either direction 
through the membrane, which is permeable to them; the sugar molecules, 
on the other hand, cannot pass out, for to them the membrane is imper- 
meable. As a result of the presence of the sugar on the inner side of 
the membrane, in unit time, more water enters the pot than passes out, 
and the pressure rises until it is sufficient to bring about the condition 
of equality in the number of water molecules entering and leaving the pot. 

This pressure is called the osmotic pressure of the solution of sugar, 
under the conditions of concentration and temperature. That this 
pressure is comparable to that of a gas was first clearly pointed out 
by van ’t Hoff-? 

Thus the osmotic pressure of a dilute solution at constant tem- 
perature is proportional to its concentration (7.e. density of a gas in 
the law of Boyle). This is illustrated by the following table from 
Pfeffer : 3— 

Cane Sugar Solutions at 13°°5 C. to 16°°1 C. 


| Concentration of Osmotic Pressure Osmotic Pressure 
Solution. | in Mm. of Hg. Concentration 


1 per cent. 535 535 
2 AS 1016 | 508 
| 2°74 ae 1518 554 
4 a 2082 521 
| 6 ne | 3075 | 513 


Again, at constant concentration of a dilute solution, the osmotic 
pressure is proportional to the absolute temperature (law of Charles). 
Thus, again, taking Pfeffer’s data— 


1 per Cent. Cane Sugar Solution. 


Temperature. Observed Pressure. | Calculated Pressure. 
Mm. Hg. Mm. Hg. 
(cl) 32° 544 sie 
14°15 510 512 
| (2) 36° 567 se 
| | Wetec) 520°5 | 529 


1 For details of manufacture see Adie, Journ. Chem. Soc., London, 1891, vol. lix. p. 344. 

* Arch. neérl. d. sc. exactes, etc., 1885, Bd. xx. S. 239; Zetschr. f. physikal. Chem. 
Leipzig, 1887, Bd. i. S. 479. 

* Loc. cit., p. 85. 


266 DIFFUSION, OSMOSTS, AND FILTRATION. 


The experiments of Soret,! again, show that in a solution, as in a gas, 
the warmest part is the most dilute. Soret mtroduced a solution into 
a long vertical tube and maintained a difference of temperature at the 
two ends, the upper end being warmer than the lower. At the end 
of several weeks the concentration of the solution at the warm end of 
the tube was found to be lowered. Thus, with solution of copper 
sulphate, the concentration at the end of the tube at 20° C. was 17332 
per cent., while that at the end maintained at 80° C. was 14:03 per cent., 
instead of 14:3 per cent. as calculated by Charles’ law. And, again, with 
concentration of 29°867 per cent. at the 20° C. end, a concentration of 
23-871 per cent. was found at the end warmed to 80° C. instead of 24°8 
per cent. as calculated. 

Thus “the osmotic pressure of a dissolved substance is exactly the 
same as the gas pressure, measured by the manometer, which one would 
observe if he could remove the solvent, and leave the dissolved substance 
as a gas filling the same volume.”? The hypothesis of Avogadro then 
is, according to van ’t Hoff, not merely capable of extension by the law 
of Henry to solutions of gases, but to solutions of matter which is not 
gaseous under ordinary circumstances, and it may be stated that 
equal volumes of gases or dilute solutions at the same gas or osmotic 
pressure, and at the same temperature, contain equal numbers of 
molecules. 

A marked concordance is seen in the table below, between the 
observed osmotic pressures for sugar solution taken from Pfeffer * and 
those calculated on the hypothesis of Avogadro and the law of Charles. 


One per cent. sugar solution contains 1 grm. of sugar in 100°6 cc. of 
solution. At the same temperature and pressure, ;35 of a grm. of hydrogen 
contains by hypothesis the same number of molecules (C,,H,,0,, = 342). 

Taking the weight of a litre of hydrogen, at 0° C. and one atmosphere 
pressure, as ‘08956 grm., and the above concentration as ‘0581 grm. per litre, 
the gas pressure at 0° C., at the volume 100°6 e.c., is 649 atmosphere, and at 
the temperature #= 649 (1 + 003677). 


Observed Osmotic | Calculated Gas 


Temperature. } Pressures 
I | Pressures.4 “649 (1+ 00367t). 
= ee) 
6°°8:C. “664 “665 
meas “691 “681 | 
| 14°2 C. 671 “682 
THs His “684 “686 
DISC! Tail ‘701 
So eis 716 725 | 
36, C. ‘746 °735 


The law of Dalton may also be applied, with certain restrictions, to 
the osmotic pressure of solutions, the total pressure of a mixture of 


substances being equal to the sum of the partial osmotic pressures of 
the several components. 


1 Arch. d. sc. phys. et nat., Geneve, Sér. 3, tome ii. p. 48 ; Ann. de chim., Paris, Sér. 5, 
tome xxii. p. 293. 


? Nernst’s ‘‘ Theoretical Chemistry,” 1895, Palmer’s trans., p. 148. 
3 Loc. cit. + Pfeffer, loc. cit., p. 85. 


OSMOSIS. 267 


The following instances are taken from Pfeffer : '— 


Copper Ferrocyanide Membrane. 


RISE OF FLUID IN MEASURING TUBE 
IN Mo. Per Hour. 


CONCENTRATION. 


| 
Experiment I. Experiment II. 
| Temp. 17°1C. Temp. 15°°8 C. 
Mm. Mm. 
1 per cent. saltpetre . : ‘ 6°08 54 
15 ni gum-arabic : ; 2°06 1°8 
1a ea saltpetre + 15 per cent. | 7°90 70 
gum-arabic 
1 per cent. saltpetre . 4 : 6°06 5°3 


Parchment Paper Membrane. 


RISE OF FLUID IN MEASURING TUBE 
IN Mo. PER Hour. 
CONCENTRATION. 
Experiment I. Experiment II. 
1°5 per cent. calcium chloride. 9-9 10°3 
2 35 gum-arabic . : 1-2 | 1:3 
15 ae calcium chloride+2 | 11°4 sea lige 
per cent. gum-arabic se 


Temperature in both experiments, 17°°4 C. 


In cases, however, where the two constituents of the solution have 
a common ion, each salt diminishes the dissociation of the other, so that 
the pressure of the mixture is less than the sum of the pressures of the 
two components.” 

Thus for a double salt— 


| 

A. B. 

Osmotic Sum of | Osmotic Sum of | 

Pressure. Components. __— Pressure. Components. | 

zs(NH,).SO, ee ee V2 Lp 1295 
=n Ct) ae 1:265 ,, se laanl22 
- 2;K.80, : : : 12) oe os 1°40 Asp 
wr(NH,),Al.,(SO,),24Aq Dry ares 2°53 1:98 2°515 
Pp K,Al,(SO,),24Aq . | 2°39. 5, 2°56 1:96 2°62 


1 Pfeffer, Zoc. cit., p. 68. 
2 From Adie, Journ. Chem. Soc., London, 1891, vol. lix. p. 344. 


268 DIFFUSION, OSMOSTS, AND FILTRATION. 


It is, however, by no means the fact that, in the case of all sub- 
stances in aqueous solution, agreement exists between the observed 
osmotic pressure and that directly calculated on the above hypothesis 
alone. In many cases the pressures observed in solution are far higher 
than those calculated from the concentration in eramme-molecules per 
unit volume. Thus the osmotic pressure of a 1 per cent. aqueous solu- 
tion of common salt at 0° C., by calculation on the above data, should 
be 3°79 atmospheres, but actual measurement shows it to be over 7 
atmospheres. 

This phenomenon, common to all solutions of electrolytes, is 
accounted for on the hypothesis of Arrhenius,’ that the dissociated ions 
of an electrolyte in solution are capable of exerting pressure as well as 
the undissociated molecules. The osmotic pressure of solutions of 
electrolytes is then raised above the simple molecular value by the 
coetlicient expressing the extent to which the molecules are dissociated 
in passing into solution (dissociation coefficient). 

This coefficient gives the ratio of the observed osmotic pressure of a 
solution to the pressure calculated on the assumption that no dissocia- 
tion of molecules occurs in passing into solution. It may be deter- 
mined for a substance at a particular dilution most accurately, by 
measurement of the electrical conductivity of the solution. 

If m is the number of inactive molecules in the solution, and 7 the 
number of active, and /: the number of ions into which a molecule can 


mt+kn 
mtn 


is measurable by the 


be dissociated, then the dissociation coefficient 7 = 


n 
m+n 
ratio of the molecular conductivity of the solution to the limiting value 
it approaches by increased dilution, i=1+(k-1)a can be obtained 
by measurement of conductivi ity of solution. 7 can obviously also be 
obtained from measurements of osmotic pressure. 

This coefficient will necessarily be of very different value for 
different classes of electrolytes, since the possible number of ions is 
variable. Thus sodium chloride has 2, potassium sulphate 3, 
potassium ferrocyanide 5 ions. 

Hence as a formula may be given— 


Since the “ activity co-efficient ” ¢ = 


P = 2235 (1+-00367t) © 7 atmospheres, 


Til 


where 22°35 atmospheres is the pressure exerted by the gramme- 
molecule of gas in volume of 1 litre at 0° C., ¢ the number of grammes 
of the substance per litre, m its molecular we eight, and 7 its dissociation 
coefficient at the concentration e. 

As regards the practical estimation of the osmotic pressure of a 
solution, the direct measurement by a semipermeable membrane is not 
only tedious, and limited to cases where the dissolved substance has no 
chemical action on the -film, but seldom practicable, on account of the 
difficulty in constructing membranes, to which the term may be strictly 
applied. Obviously, unless the membrane is really impermeable to the 
dissolved substance, the values on account of the “ leakage ” of dissolved 
substance must be below the real amount. 


‘ Ztschr. f. physikal. Chem., Leipzig, 1887, Bd. i. S. 631. 


OSMOSIS. 269 


Blagden ! discovered the fact that the freezing-point of a solution is 
lower than that of the solv ent, and that the lowering of freezing-point 
is proportional to the concentration of the solution. Riidorff,? Coppet, 
and Raoult * have since more thoroughly investigated the matter. If, 
therefore, we know the lowering of the freezing- point of water, produced by 
the addition of a gramme- molecule to the litre (ats i C.), and the osmotic 
(or gas) pressure at 0° C. corresponding to this (22°35 atmospheres), it is 
merely a matter of simple proportion to calculate the pressure at 0° C. 
corresponding to any given lowering of freezing-point, and from that to 
obtain the pressure at any other temperature by the law of Charles. 

Many pieces of apparatus have been devised for measuring the 
lowering of the freezing-point, but that of Beckmann’ is in most 
general use. Unfortunately, the method does not yield concordant 
results in the hands of different observers (when aqueous solutions 
are used) within about 005° C., which corresponds to an osmotic pressure 
of about 50 mm. of mercury at the temperature of the body (37° C.), and 
is hence of little value for the correct estimation of small differences of 
osmotic pressure in the aqueous solutions to which the physiologist 
confines his attention." 

An optical method has been used by Tamman.7 If a drop of 
solution of potassium ferrocyanide is allowed to fall into a solution 
of copper sulphate, a so-called “Traube cell” is formed, the ferrocyanide 
solution within which is separated from the copper sulphate solution 
outside by a precipitation membrane of copper ferrocyanide, through 
which osmotic interchange can take place. 

If the internal solution be of higher osmotic pressure than the 
external, water passes from the copper solution outside into the 
cell, and the copper solution immediately round about the cell, being 
raised in concentration, tends to sink. In the reverse case, by dilution 
of the layer round the cell, an upward current is started. There are 
thus produced differences in the refractive index of the layer of solution 
against the outside of the cell, in contrast to the rest of the copper 
solution. These are easily detected by the Topler Schlierenapparat.® 
If the ferrocyanide solution have the same osmotic pressure as the 
copper solution, no schlieren will be produced, and there will be no 
change in refraction. Now, since the total osmotic pressure is the sum 
of the partial pressures, a third substance, not reacting with the 
membranogens, may be added to the solution of one of them, and the 
concentration of the other, isosmotic with the mixture, determined by the 
method. Since the osmotic pressure of the solution of the mem- 
branogens, to which the third substance was added, is_ directly 
measurable, it is obvious that the partial pressure of the added 
substance can be measured. 


1 Phil. Trans., London, 1788, vol. lxxviii. p. 277. 

2 Ann. d. Phys. u. Chem., Leipzig, 1861, Bd. exiv. S. 63 ; 1862, Bd. exvi. S. 55 ; 1871, 
Bd. exlv. S. 599. 

5 Ann. de chim., Paris, 1871, Sér. 4, tome xxiii. p. 366 ; 1872, tome, xxv. p. 502 ; 1872, 
tome xxvi. p. 98. 

4 Tbid., Paris, 1884, Sér. 6, tome ii. p. 66; Compt. rend. Acad. d. sc., Paris, 1882, 
tome xcy. p. 1030. 

> Ztschr. f. physikal. Chem., Leipzig, 1888, Bd. ii. S. 638. 

6 Loomis, Ann. d. Phys. u. Chem., Leipzig, 1894, Bd. li. S. 500; Jones, Ztschr. f. 
physikal. Chem., Leipzig, 1893, Bd. xi. a 110; Raoult, ibid., 1892, Bd. ix. 8. 343. 

7 Ztschr. f. physikat. Chem., Leipzig, 1888, Bd. ii. §. 415. 

8 Ann. d. Phys. u. Chem., Leipzig, 1867, Bd. cxxxi. S. 33. 


270 DIFFUSION, OSMOSIS, AND FILTRATION. 


Physiological methods of estimating osmotic pressure have also been 
devised. The method of de Vries! is based upon the plasmolysis of the 
protoplasts of vegetable cells. The cells filled with coloured sap from 
the middle nervure of the leaf of TZvadescantia discolor are useful 
for the purpose, sections of this part being allowed to soak for three to 
five hours in the solutions whose osmotic pressures are to be determined. 
If the cells are plasmolysed, i.e. if the protoplasts are found on 
examination to have shrunk from the cell walls, the osmotic pressure 
of the solution producing this effect is above that of the cell sap, for 
water has passed from the latter to the former, as evidenced by the 
diminution in volume. By investigating a series of solutions with 
sections from the same leaf, it is of course possible to find two of 
slightly differing concentration of the substance under investigation, 
one of which just causes plasmolysis, while the other (weaker) does 
not. <A solution of concentration equal to the mean of these two is 
said to be dsotonie with the cell sap. 

De Vries, on preparing a number of solutions of different substances, 
all isotonic with the same batch of cells, and expressing their 
concentrations in gramme-molecules to the ltre, found that it required 
a lower gramme-molecular concentration of some substances than of 
others to obtain isotony. The term “water extracting power” 
(Wasseranziehungsvermoyen) was used to express this peculiarity which 
is obviously related to what has above been termed dissociation. 
Taking 0-1 grm. molecule to the litre of saltpetre as a standard, and 
giving it a magnitude : 3, the relative value (as regards plasmolysis 
of vegetable cells) of ¢ molecule. of a number of substances was 
expressed i in terms of that of a molecule of saltpetre, and the numbers 
expressing this ratio called isotonie coefficients of the substances. 

Thus, to barium chloride (BaCl, + 2Aq = 244) is given the 
isotonic coefficient 4, which means that $244 parts by weight of 
barium chloride in aqueous solution exert the same plasmolysing 
action as 101(KNO,=101) parts by weight of saltpetre ae. a 185 
per cent. solution of crystallised barium chloride is isotonic by the 
method, with a 1-01 per cent. solution of potassium nitrate. 

Since cane sugar on this system is given the value of 2 for its 
isotonic coefficient, and since, being a non-electrolyte, it is not 
dissociated in solution, it is merely necessary to div ide the isotonic 
coefficients of de Vries by 2, in order to obtain ordinary dissociation 
coefficients. 

It is obvious that the substances in solution must exert no 
deleterious action on the protoplast of the cell, and must, moreover, 
be quite unable to diffuse through it, if the method is to be exact. 

Here, again, we are met with the difficulty, that the protoplast is 
not a strictly semipermeable membrane. It must let certain substances 
pass, otherwise the cell sap could not have any other constituent than 
water; and it is only because the permeability to certain substances is 
so far below that to water, that it is possible to obtain fairly approximate 
measures of osmotic pressure by this method. With other substances 
the permeability is so great that the values are far too low. 

Thus with sodium chloride, by this method, the dissociation coefficient 
is reckoned as 1:5 (de Vries’ isotonic coefficient 3), but by lowering of 


1 Jahrb f. wiss. Botanik, 1884, Bd. xiv. 8. 427; Zischr. f. physikal. Chem., Leipzig, 
1888, Bd. ii. S. 415. 


OSMOSTS. CU 


freezing-point method, it is found to be higher (about 1°89). Other 
indices of “isotony” than the plasmolysis of the vegetable cell have 
been used by physiologists. 

Hamburger! has used red blood corpuscles. If these are placed 
in solutions of substances which do not penetrate, and which do not 
act chemically upon them, an index of the entrance of water into 
the substance of the corpuscle is presented by the setting free of 
hzemoglobin, which is recognisable in the solution. In a solution of lower 
osmotic pressure than the corpuscle-contents (hypoisotonic solution), 
water enters the corpuscles and the solution is reddened. In a solution 
of higher osmotic pressure than the contents (hyperisotonic solution), 
water is extracted from the corpuscles, they shrivel and sink, and the 
solution retains its original colour. Two limiting solutions are thus 
obtainable, and the mean concentration of the two is taken as that 
isosmotic with the contents of the corpuscle. 

The method has very considerable limits in practice, for not only 
is it obviously restricted to colourless solutions, but it can also only 
give results approaching the truth, in cases where the substance in 
solution does not penetrate; and, as indicated by Gryns,” who has 
criticised the method very severely, the red corpuscles are penetrable 
by a very large number of substances.* 

Another blood corpuscle method is that of the hematokrit.* Here 
the gauge of entrance or exit of water from the corpuscles is the volume 
they occupy, in a graduated capillary tube, after having been centrifu- 
galised with the solution. The volume of the corpuscles is dependent 
on the osmotic pressure of the solution in which they are placed (provided 
the dissolved substance does not penetrate), and if equal volumes of the 
same blood specimen, contemporaneously centrifugalised in two solutions 
of different substances, give the same volume of corpuscles, those solutions 
have the same osmotic pressure. By centrifugalising a given volume 
of a blood sample in a series of solutions of a substance not penetrating 
corpuscles (cane sugar), of different and known osmotic pressure, in 
separate tubes, at the same time as an equal volume of the same blood 
treated with the solution of the substance to be investigated, a final 
comparison of the length of the “threads” of corpuscles in the tubes 
gives a gauge of the osmotic pressure of the solution. 

By centrifugalising blood in a pipette, previously oiled (cedar oil) 
to prevent clotting, measuring the length of the “thread,” and 
comparing with the same, blood treated with sugar solutions of known 
osmotic pressure, the pressure of the plasma is determinable and is 
found to vary, rising after meals, and especially after the ingestion 
of solutions of salt (Koeppe). 

A bacterial method even has been used by Wladimiroff? who has 


l Arch. f. Anat. u. Physiol., Leipzig, 1886, Phys. Abth., S. 476; 1887, S. 31; 
Ztschr. f. physikal. Chem., Leipzig, 1890, Bd. vi. S. 319. 

2 Arch. f. d. ges. Physiol., Bonn, 1896, Bd. |xiii. S. 86. 

%’Hamburger himself (Zschr. f. physikal. Chem., Leipzig, 1890, Bd. vi. S. 319) 
maintained that permeability did not affect his method, since, by a ‘‘ vital act” 
(‘‘ Lebenserscheinung’’), S. 331, the corpuscles give up to the solution from their juice 
an amount of some other substance exactly equivalent to that which penetrates from 
without, so that the total osmotic pressure of the juice is unaltered ! 

4Hedin, Skandin. Arch. f. Physiol., Leipzig, 1890 ; Gaertner, Berl. klin. Wehnschr., 
1892, Bd. xxix. S. 36; Koeppe, Arch. f. Physiol., Leipzig, 1895, S. 154; Arch. f. d. ges. 
Physiol., Bonn, 1896, Bd. lxii. S. 567 ; Miinchen. med. Wehnschr., 1893, No. 24. 

5 Zischr. f. physikal. Chem., Leipzig, 1891, Bd. vii. S. 529. 


272 DIFFUSION, OSMOSIS, AND FILTRATION. 


maintained that cessation of motion of bacteria placed in solutions 
indicates that the solution is isosmotic with the cell sap, in cases 
where poisonous action can be excluded. 

The above physiological methods of measuring osmotic pressure are 
of considerable interest, but, as already stated, their application is 
decidedly limited; and though, as will appear below, often of indirect 
value, as giving information bearing on the permeability of cells and 
membranes, they are not to be classed with the more accurate methods 
of experimental physics. 

In the case of colloid solutions, it is not necessary to use pre- 
cipitation membranes for the direct measurement of osmotic pressure, 
for such material as vegetable parchment is, as a rule, impermeable to 
colloids, and it moreover presents certain advantages in particular 
cases, namely, those in which the colloidal substance is contaminated 
by salts (eg. albuminous solutions), since the salts can pass out, and 
the determination is freer from the error of inclusion of the partial 
pressure of these, unavoidable by a direct measurement by a copper 
ferrocyanide membrane, or an indirect determination by lowering of 
freezing-point. 

It is known that solutions of colloids of considerable concentration 
exert very low osmotic pressure, though their exact measurement is 
difficult. Picton and Linder, in a direct measurement (by a copper 
ferrocyanide membrane) of the pressure of a 4 per cent. solution 
of colloidal arsenious sulphide, obtained a pressure of only 17 mm. of 
water. Sabanejew®” states that the lowering of freezing-point by silicic 
acid is so small as to be within the limits of the method. With 
albuminous solutions the difficulty of contaminating salts is almost 
insuperable, and since the molecular weight of albumin is not known, 
calculation is excluded. 

Sabanejew® investigated the lowering of freezing-point of water by 
solution of egg albumin, and quotes a lowering of 02° C. for a 15°6 per 
cent. solution, and ‘042° C. for a 30°35 per cent. solution, but since the 
specimens held -4 to ‘66 per cent. of ash, the numbers are of no value. 
Tamman#‘ gives the difference in lowering of freezing-point of horses’ 
serum, produced by coagulation of the proteids by heat and removing 
them, as only ‘006° C., which is in the region of the error of the method. 
Dreser® and Koeppe? also state that the removal of proteid from 
albuminous solutions does not affect the osmotic pressure, while 
Liideking®’ maintains that the boiling point of 40 per cent. solution 
of gelatin is 100° C.° It is therefore uncertain whether proteids in 


1 Journ. Chem. Soc., London, 1895, vol. Ixvii. p. 63. 

* Ber. d. deutsch. chem. Gesellsch., Berlin, 1890, Bd. xxiii. 8. 87. 

3 Toid., 1891, Bd. xxiv. S. 558. 

4 Ztschr. f. physikal. Chem., Leipzig, 1896, Bd. xx. S. 180. 

> Starling, on the other hand, quotes two experiments to prove that the osmotic 
pressure of the proteids of serum can be directly measured. It is stated to be from 30 to 
40 mm. of Hg. Journ. Physiol., Cambridge and London, 1895, vol. xix. p. 323. Cf. also 
next article, p. 308. 

6 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1892, Bd. xxix. 8. 314. 

7 Arch. f. d. ges. Physiol., Bonn, 1896, Bd. Ixii. S. 571 (footnote). 

8 Ann. d. Phys. u. Chem., Leipzig, 1888, Bd. xxxv. S. 552. 

®A lowering of vapour pressure (raising of boiling point) is produced by solution 
of a substance in a solvent, and the lowering of vapour pressure, like that of the 
freezing-point, is proportional to the concentration. Wiillner, Ann. d. Phys. u. Chem., 
Leipzig, 1858, Bd. cili. S. 529; 1858, Bd. cv. S. 85; 1860, Bd. ex. S. 564 ; Tamman, 
Ann. d. Phys. wu. Chem., Leipzig, 1888, Bd. xxxiv. 8S. 299. 


OSMOSTS. 273 


colloidal solution exert an osmotic pressure capable of measurement 
by our present methods. 

From the above account of osmotic pressure, it is evident that, 
since it is present in high or low degree in all true solutions, as a result 
of the kinetic energy of the dissolved molecules, the phenomena of 
diffusion are most satisfactorily accounted for as directly dependent 
on the osmotic pressure exerted by the diffusing substance.’ Substances 
diffuse from places of higher to those of lower partial pressure, and 
the differences in rapidity of diffusion of different substances, though 
present in concentrations exerting the same osmotic pressure, must be 
accounted for by differences in the resistance met in their passage 
among the molecules of the solvent. 

When we now turn to the consideration of the interchange of the 
constituents of solutions through animal membranes, we at once find 
that, since these membranes are never strictly semipermeable, and are 
frequently very permeable for dissolved substances, the phenomena are 
neither those of pure osmose nor pure diffusion, but a complex of 
the two, in which the relative permeability of the membrane to solvent 
and dissolved substance is of paramount importance, but, unfortunately, 
a variable factor with different membranes.2 All the earlier work upon 
osmosis was carried out with membranes not fulfilling the condition of 
semipermeability, so that a double stream of solvent into solution 
(endosmose) and dissolved substance into solvent (exosmose) was con- 
sidered as a necessary feature of the process until Traube’s discovery of 
precipitation membranes. 

The first osmose experiment was probably that of the Abbé Nollet, 
in which it was observed that a bladder tied over a vessel of spirits of 
wine became distended, or even burst, when vessel and membrane were 
under water. Parrot+ again called attention to the fact, which 
had been forgotten, and ascribed the process to “affinity of the first 
order,’ which causes all miscible fluids to “wander” into one another. 
Fischer® in Germany and Dutrochet® in France again rediscovered 
the prime fact, and commenced its systematic study. Certainly the 
main stimulus to subsequent study of the phenomena was given 
by the work of Dutrochet.? Dutrochet’s endosmometer was a funnel 
closed by membrane and provided with a long stem. The body 
of the funnel was filled with the solution, and the whole immersed 
in water. The height to which the fluid rose in the stem was the 
gauge of the osmotic action of the solution. Dutrochet recognised 
that the concentration of the solution and the temperature affected 
the results. 

Vierordt § improved upon the arrangement used by Dutrochet, by 
setting the membrane vertical and the stem horizontal, so that filtration 
error was avoided, and also concluded that the stream of water into the 


1 Nernst, Ztschr. f. physikal. Chem., Leipzig, 1888, Bd. ii. S. 611. 

2 In this connection see a paper by Lazarus Barlow, Journ. Physiol., Cambridge and 
London, 1895, vol. xix. p. 140. 

3 “¢ Histoire de ]’Académie royale des sciences,” 1748, p. 101. 

4 Ann. d. Phys. u. Chem., Leipzig, 1815, Bd. li. S. 318. 

5 Tbid., 1822, Bd. lxxii. 8. 300. 

6 Ann. de chim., Paris, 1827, tome xxxv. p. 393; ‘‘ Agent immédiat du mouvement 
vital,” Paris, 1826. 

7 See also ‘‘ Mémoires pour servir 4 l’histoire anatomique et physiolegique des vegétaux 
et des animaux,” Bruxelles, 1837. 

8 Ann. d. Phys. u. Chem., Leipzig, 1848, Bd. lxxiii. S. 519. 


VOL. I.—18 


274 DIFFUSION, OSMOSIS, AND FILTRATION. 


funnel was proportional to the difference of concentration of the solu- 
tions on either side of the membrane. 

Jolly! specially studied the ratio between the amount of water 
passing into the solution and the amount of dissolved substance passing 
out, using salts with pig’s bladder as membrane. This ratio he termed 
the endosmotic equivalent of the salt, and maintained that it is constant 
for the same membrane, concentration of the salt solution, and tem- 
perature. For some years after this the whole attention of those interested 
in the matter of osmosis was directed to a fuller study of this ratio in 
the case of different substances.? 

As a result of these researches, it was seen that even with the same 
membrane it was only within slight changes of concentration of the 
solution that constancy of the endosmotic equivalent was obtainable, a 
result in accordance with expectation, seeing that the physical nature of 
an animal membrane must necessarily undergo change with the amount 
of water imbibed, a quantity variable with the concentration of the solu- 
tions in which it is in contact. With a strictly semipermeable membrane, 
the endosmotic equivalent is evidently infinite, while the more permeable 
the membrane to dissolved substance the lower will be the equivalent. 
Thus, according to Harzer,’ the endosmotic equivalent for sodium chloride 
is with fish-swim-bladder, 2°9 ; ox-pericardium, 4:0; ox-bladder, 6:4. 

It must therefore be admitted that, in spite of the great labour that 
has been expended on the determination of endosmotic equivalents of 
different substances with different membranes, the results obtained are 
of little value to the practical physiologist, who deals with membranes 
in the living body, whose physical characters are by no means necessarily 
those of the structures used in such experiments. The only value that can 
be attached to these determinations is an orienting one, as to the diffusi- 
bility of the substances into water, through dead animal membranes, 
under the conditions of the experiments. 

Before we can attempt to answer the question, How is the process of 
diffusion modified when in an osmose experiment an animal membrane 
is placed between solution and solvent? it is obviously necessary to 
know the physical structure of the membrane. Of this we must admit 
great ignorance. To Briicke* we owe a theory of “pore diffusion.” 
Assuming capillary pores in the membrane, it maintains that, by 
attraction, a layer of pure water lines these, while an axis of salt solu- 
tion, whose concentration falls from axis to mantle of the cylindrical 
pore, lies centrally. The highest concentration in the axis must be that 
of the salt solution in the experiment, and along the axis ordinary 
hydrodiffusion takes place, water entering the salt solution and salt 
entering the water. Along the mantle, however, only water can pass 
into the salt solution, so that the stream of water exceeds that of salt. 
If the pores are very narrow, it is conceivable that there is no central 
core of salt solution, in fact the membrane becomes semipermeable. 


1 Ztschr. f. rat. Med., 1849, Bd. vii. p. 83; Ann. d. Phys. u. Chem., Leipzig, 1849, 
Bd. Ixxviii. 8S. 261. 

* Fick, Untersuch. z. Naturl. d. Mensch. u. d. Thiere, 1857, Bd. iii. S. 294 ; W. Schmidt, 
Ann. d. Phys. u. Chem., Leipzig, 1857, Bd. cii. S. 122; Beitr. 2. Anat. u. Physiol. 
(Eckhard), Giessen, 1855, Bd. i. S. 97; 1860, Bd. ii. S. 1, 31, 147; Hoffmann, zid., 
1860, Bd. ii. S. 59. 

° Arch. f. physiol. Heilk., Stuttgart, 1856, Bd. xv. 8. 194. 

* “De ditlusione humorum per septa mortua et viva,” Berlin, 1842; Ann. d. Phys. w. 
Chem., Leipzig, 1843, Bd. lviii. S. 77. 


OSMOSIS. 275 


The attraction of the substance of the membrane for water, at any 
rate, may then be a factor in the case. Ludwig! demonstrated, indeed, 
that the concentration of the solution imbibed by an animal membrane 
may be lower than that of the solution in which it is soaked. 

Fick ? distinguished between two possibilities for diffusion through an 
animal membrane —a “pore diffusion” in Briicke’s sense, and a 
diffusion occurring through the spaces between the molecular aggregates 
of which the membrane may be considered to be built. The latter idea 
is somewhat of the nature of that formed of the diffusion of a gas 
through a film of liquid in which it is soluble, or is perhaps better 
illustrated in the experiment of L’Hermite,? in which, when water 
separates chloroform from ether in a tube, the chloroform increases at 
the expense of the ether. Fick’s “homogeneous” membranes were 
made of collodion; but his results show that such a membrane is not 
unalterable, simce the amount of salt passing through increases with 
time, and it is difficult to escape the conclusion that in many cases 
some interaction of chemical nature takes place between the membrane 
and the substances to which it is permeable.* 


The property possessed by certain substances of imbibing certain liquids 
(apart from capillary action), must be borne in mind in all considerations of the 
essential nature of the processes involved in the passage of fluids through 
membranes. This property can only be ascribed to some “affinity” between 
the molecules of the imbibing substance and that imbibed; thus gelatin 
swells in water but not in ether, while the reverse is true of caoutchouc. The 
retention of a gas, or a colouring matter by charcoal, of water by the silica 
of the opal, or that of pepsin by fibrin, are instances of the class of phenomena 
to which attention is here called, and to which the name of adsorption is often 
applied. When a homogeneous substance imbibes a solution, compounds of 
the imbibed with the imbibing substance may be formed, which may have a 
greater affinity for the solvent than the original imbibing substance, but at the 
same time the osmotic pressure of the solution tends to retard the imbibition 
of the solvent; hence, with a given pair of substances, the amount of the 
solution of one taken up by the other will reach a maximum at a certain con- 
centration, a maximum, however, which may be wellabove that for imbibition 
of the pure solvent. 

The “affinity” of the imbibing substance for the solvent and dissolved 
substance imbibed may be of very different order, for gelatin takes up a more 
concentrated solution of methyl-violet than that in the “dye- -bath ; while, on the 
other hand, a ferrocyanide of copper membrane will take up water while almost 
absolutely indifferent to dissolved cane sugar. 

Such “affinities” are not purely mechanical, since they vary with the 
chemical nature of the substances, and yet are not of the nature of chemical 
affinity in the usual sense of the term, since the ‘‘compounds” do not obey the 
laws of constant and multiple proportion. Ostwald has introduced the term 
mechanical affinity to meet the case. 

In the complex known as protoplasm there may be imbibing substances of 
different nature, permeated by a solution of substances whose chemical nature 
may, directly and indirectly, affect the imbibition of a solution brought in 
contact with the mass; and, furthermore, undissolved particles may themselves 


1 Zischr. f. rat. Med., 1849, Bd. viii. S. 1; Ann. d. Phys. u. Chem., Leipzig, Bd. 
Ixxviii. S. 307. 

2 Untersuch. z. Naturl. d. Mensch. u. d. Thiere, 1857, Bd. iii. S. 294. 

3 Ann. de chim., Paris, 1854, Sér. 3, tome xliii. Dp: 420. 

4Tamman, Zéschr. f. physikal. Chem. , Leipzig, 1892, Bd. x. S. 255 ; Walden, ibid., S. 699. 


276 DIFFUSION, OSMOSIS, AND FILTRATION. 


exert surface action, so that the possibilities for purely physical absorption are 
quite unknown, and so-called vital elective action may be the result of specific 
adsorptive affinity. Hofmeister ! has shown that gelatin has an “elective” action, 
for common salt, the concentration of the solution imbibed exceeding that of 
the surrounding solution ; and, further, that the combination of sodic chloride 
with the gelatin favours the uptake of water. Again, gelatin takes up more 
water from *5 to 2 per cent. solution of ethyl-aleohol in water than from pure 
water. 

With salts that undergo electrolytic dissociation in solution, permeability 
must be a function of ions. Thus, according to Ostwald,? copper ferrocyanide 
is permeable to potassium chloride, because both chlorine and potassium ions can 
pass ; it is impermeable to barium chloride, because the barium ion is stopped ; and 
impermeable to potassium sulphate, because the sulphuric acid ion cannot pass ; 
and, under ordinary circumstances, on account of opposite electrical charges, if 
one ion is stopped, so must be the other. There are, however, conditions 
under which an ion, stopped on account of the impermeability of the membrane 
to its fellow in a salt, may pass the membrane. 

If the negative ion of a salt is prevented from passing through the 
membrane, only because it is impermeable to its positive fellow, the addition of 
another salt, whose positive ion can pass the membrane, will allow the negative 
ion of the first salt to pass in company with it. Or a salt whose negative ion 
can pass the membrane may be placed on the opposite side, the two negatives 
exchanging with their positive fellows across the membrane, and equal numbers 
of the two negative ions passing in opposite directions in a given time. This is 
of interest to the physiologist, since it opens a possible physical explanation of 
the fact that a cell may hold back a substance under certain conditions, while 
under others, when surrounded by a differently constituted fluid, the same 
substance may be given up. 

Koeppe® has attempted to apply this to the formation of hydrochloric acid 
in the stomach from sodium chloride, maintaining that the stomach wall is 
impermeable to chlorine ions, but that the sodium ions are exchanged for 
hydrogen ions from the blood. That free hydrogen ions are present in the 
alkaline blood is, however, hardly possible. 


Whether permeability be a function of physical or chemical nature, it 
is obvious that in the case of a living membrane the complex to which 
the term “ physiological condition” is applied must affect the property, 
so that one and the same membrane in the body may, under different 
circumstances, be more or less permeable by the same substance. 

The simplest living membrane with which experiments can be made 
is probably the differentiated outer layer of the protoplast of the vege- 
table cell (Plasmahaut). There is no doubt that the permeability of this 
membrane for different chemical substances is very variable. It is pene- 
trated by some dye-stuffs but not by others, very impermeable to 
many simple salts, though easily permeable by certain complex organic 
substances.4 Since this membrane is in its living condition so 
slightly permeable to salts, the osmotic pressure within vegetable cells is 
high (8 to 4 atmospheres). This special relative impermeability to salts 
is obviously regulated in some manner by the “ physiological condition ” 
of the membrane. Jansen® found that the cell sap of the alga, Cheto- 

1 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1891, Bd. xxviii. 8. 210. 

* Zischr. f. physikal. Chem., Leipzig, 1890, Bd. vi. S. 71. 

3 Arch. f. d. ges. Physiol., Bonn, 1896, Bd. Ixii. S. 567. 

4 Pfeffer, Abhandl. d. math.-phys. Cl. d. k. stichs. Geselisch. d. Wissensch., 1890, Bd. 


xvi. S. 149. 
> Verhandl. d. k. Akad. v. Wetensch., Amsterdam, 1888, vol. iv. p. 345. 


OSMOSIS. 277 


morpha, growing in sea water, is practically isosmotie with that of 
Spirogyra, growing in fresh water, though the osmotic pressure of sea 
water is some 240 times that of fresh. Thus the osmotic pressure of the 
cell sap of Chatomorpha is far below that of the water in which it lives, 
while that of the sap of Spirogyra is far above that of fresh water. 

One can investigate the permeability of the living protoplast by the 
plasmolytic method already alluded to above. The cell is plasmolysed 
with a solution of some substance indifferent to the protoplasm and known 
not to penetrate (sugar). A solution of the substance to be tested is now 
prepared of the same osmotic pressure as the solution of indifferent 
substance which just causes plasmolysis. If the solution so prepared has 
exactly the same effect as the standard, it cannot pass through the proto- 
plast, for, if it did, there would no longer be equality of osmotic pressure 
on the two sides thereof. If the substance to be tested is only slightly 
soluble in water, or is poisonous to the protoplasm, a small amount of it 
is added to the standard indifferent solution, and the effect of the 
addition on the plasmolysis noted. If it does not pass the membrane, 
then, by virtue of the higher osmotic pressure due to its addition, the 
mixture will produce more plasmolysis than did the standard solution, 
and the effect will be lasting. If no effect results from the addition, it 
must pass quickly through the membrane; if a passing effect, with 
subsequent recovery, it must pass slowly. 

In this way Overton! has investigated the permeability of the 
protoplast by a number of chemical substances, and finds that salts 
much dissociated in solution hardly pass the membrane, while many 
complex organic bodies rapidly penetrate, and that the presence of 
certain radicles in these markedly affects the result. 

In animal cells investigations are rather limited (by the fact that 
there is no plasmolysis) to shrinkage and swelling and escape of 
hemoglobin (in red corpuscles), as indices of permeability, under 
conditions of variation of osmotic pressure of surrounding solutions. 
More, therefore, is known about the permeability of the red corpuscle 
than any other cell. <A table of substances is given by Gryns,? and we 
here confine ourselves to stating that red corpuscles are permeable 
to urea, glycerin, ethyl- and methyl-alcohol, and most ammonium salts 
(not to sulphate, phosphate, and thiocyanate), impermeable to sugars, 
sodium and potassium salts, barium and calcium chlorides, glycin and 
asparagin. 

Thus, as regards action on red blood corpuscles, dilution of an isosmotic 
sodic chloride solution with urea solution produces the same effect as 
dilution with water, because the urea diffuses at once into the interior of 
the corpuscle, while, on the other hand, addition of sugar at once causes 
contraction of the cell. 

Obviously, therefore, a so-called “hyperisotonic” solution does not 
necessarily extract water from a cell, and absorption of water from such 
a solution by the blood may be a purely physical action, if the substance 
in solution can permeate the wall separating it from the blood. Again, 
a drug, by making the wall of a cell less permeable by virtue of its 
chemical action on the protoplasm, may markedly affect the “water 
extracting power” of a salt solution. Possibly the fact that some salts 


1 Ztschr. f. physikal. Chem., Leipzig, 1897, Bd. xxii. S. 189. 
2 Loc. cit., p. 102. 
3 See also Schoéndorff, Arch. f. d. ges. Phystol., Bonn, 1896, Bd. lxiii. S, 192. 


278 DIFFUSION, OSMOSIS, AND FILTRATION. 


in the intestine purge (sodic sulphate), while others do not (sodic 
chloride), may in the end find its explanation in a permeability of the 
membrane by the latter, but not by the former. <A _ universal 
“physiological salt solution,’ then, if by such a term is meant a salt 
solution in which tissues neither lose nor take up water, and the dis- 
solved substance of which does not enter the cells, is not a possibility ; 
each tissue must in fact have its own “normal solution,’! and this may 
possibly be in some cases a solution of some other substance than a 
salt. 

The effective osmotic pressure, therefore, exerted against membranes 
such as those in the body which are, as a rule, partially permeable to 
dissolved substances, is far below that measured by a semipermeable 
membrane, and freezing- -point determinations of osmotic pressures 
(determinations which give a gauge of the full osmotic pressure as it 
would be exerted against a semipermeable membrane), are of but 
orienting value to the physiologist, except in cases where the per- 
meability of the membrane to the substance in solution is known. 

The following table from Pfeffer? is illustrative of the diminution in 
the estimate of the full osmotic pressure caused by substituting a 
permeable membrane (bladder or parchment paper) for copper ferrocy- 
anide, and it is evident that the effect is far more marked in the case of 
the crystalloids (saltpetre and sugar) than in that of the colloid (gum). 


Six per cent. Solution of Parchment Paper. Bladder. Copper Ferrocyanide. 
Gum arabic . : 17°9 13°2 25°9 
Cane sugar. : 29°0 14°5 287°7 
Saltpetre : : 20°4 8:9 700°0 

(not directly estimated.) 


The pressures are in ems. of mercury. 


The conditions, then, for the interchange of water and the con- 
stituents of solutions through membranes in the body, are evidently 
exceedingly complex, and it is at present practically impossible to assess 
the value of all the factors. Broadly stated, the following factors are 
concerned :— 

1. The quantitative composition of the solutions separated by the 
membrane, and consequently the partial osmotic pressure exerted by the 
several constituents. 

2. The coefficients of diffusion of the various constituents. 

3. The permeability of the membrane in its physiological condition 
to the constituents. 

4. The circumstances affecting the relative concentrations of a 
constituent on the two sides of the membrane with time, e.g. circulation 
and stirring. 

5. The hydrostatic pressure on the two sides of the membrane. 

6. The temperature. 

The partial osmotic pressure of the constituents of a solution is 
obtainable from a quantitative analysis, if the molecular weight and 
1 Koeppe, Arch. f. d. ges. Physiol., Bonn, 1897, Bd. Ixy. S. 492. 

 “Osmotische Untersuch.,’’ Leipzig, 1877, S. 73. 


OSMOSTS. 279 


dissociation coefficient (in case of electrolytes) is known. If the 
molecular weight is not known, as in the case of proteids, the substance 
must be removed from the solution, and the difference in the total 
osmotic pressure so produced estimated. 

The coefficients of diffusion must be obtained under the special 
conditions (¢.g. diffusion into serum, etc.). 

The permeability of the membrane to dissolved substances, one of 
the most important factors, and one generally not capable of accurate 
estimation, will not only affect the passage of water and dissolved sub- 
stances across the membrane by osmotic action, but also the hydrostatic 
pressure necessary to cause filtration. 

We shall here content ourselves with considering a simple but usual 
case of absorption of a solution by blood, namely, one in which the 
osmotic pressure of the solution is lower than that of the blood, and the 
membrane separating the two permeable to the substance in solution, 
and to one at least of the constituents of the blood, but impermeable to 
others. For convenience the dissolved substance is called x, and that 
constituent of the blood to which the membrane is permeable, y. The 
blood, by virtue of its superior osmotic pressure, tends to take up water 
from the solution, and at the same time x diffuses through the membrane 
into the blood, and y into the solution. If the blood be first supposed 
to be stationary, a time is arrived at when the partial pressure of x and 
y is the same on either side of the membrane; in other words, this 
solution of # and y is now the “solvent” in an osmotic experiment, and 
the substances in the blood to which the membrane is impermeable are 
the “dissolved substances.” The whole of «, of y, and the water of the 
original solution, must therefore in the end be absorbed.! If the blood, 
however, is circulated, the conditions for absorption are at once improved, 
for the diffusion of « into the blood is favoured by the fact that its 
partial pressure in the blood is kept low by renewed supplies of blood, 
by the stirring action of the corpuscles preventing the formation of 
“wall layers,’ and by the fact that cells in other parts of the body are 
enabled to take up the substance as it is brought round. It is also 
evident from the above that if, as a rare case, the solution had a higher 
osmotic pressure than the blood, provided only the membrane separating 
the two is permeable to the dissolved substance, and impermeable to 
some constituents of the blood, when once the solution has taken up 
enough water from the blood, and lost enough of its dissolved substance 
to the blood, to lower its osmotie pressure to that of the blood, the 
process described above is gone through, and it is in the end all 
absorbed. 

For such absorption to be carried out completely, it is evident that 
the osmotic pressure of those constituents of the blood to which the 
membrane and capillary wall are not permeable, must exceed the 
pressure necessary to cause filtration across the same structures, for if 
the available osmotic pressure on the inner side of the capillary wall is 
less than the difference between the hydrostatic pressure on the two 
sides of the membrane, filtration must occur, and the solution can never 
be totally absorbed. 

The assumption is here made that the resistance to the passage of 
fluid across the membrane is the same in both directions. It must be 


1 For this explanation to hold good, the substances in the blood to which the membrane 
is impermeable must be in true solution, and capable therefore of exerting osmotic pressure, 


280 DIFFUSION, OSMOSIS, AND FILTRATION. 


noted, however, that animal membranes are known in which the 
resistance to the passage of fluid is quite different in opposite directions. 

The most familiar example is the shell membrane of the egg, which 
permits filtration far more easily from within outwards than in the 
reverse direction,! and the same is true of the skin of the frog.? 


FILTRATION. 


By filtration is meant the passage of fluid through a membrane, as a 
result of a difference of hydrostatic pressure on the two sides. To filter 
water from a solution across a membrane into another solution, the 
difference between the hydrostatic pressures on the two sides must 
exceed the difference between the osmotic pressures of the solutions, in 
the case where the higher osmotic and hydrostatic pressures are on the 
same side. If a porous pot bearing a semipermeable membrane is 
filled with a solution and immersed in the pure solvent, the pressure 
necessary to produce filtration of the solvent from the solution is one 
just exceeding the full osmotic pressure of the solution; but where we 
deal with permeable membranes, as those in the body, the necessary 
pressure is far less, because the difference of osmotic pressure on the 
two sides of the membrane is reduced by the diffusion of some of the 
dissolved substance. 

Experiments on filtration through animal membranes appear to have 
given very contradictory results, which seems to be due to the fact that 
not only does continued pressure upon such membranes vary their 
permeability, but a certain amount of “recovery” takes place in the 
intervals between use; hence the conditions of the membranes have been 
by no means uniform in the experiments of different observers. 

If the passage of fluid through an animal membrane is by more or 
less tortuous paths, and if the walls of these are more or less elastic, it 
is obvious, not only that by continued pressure must the resistance to 
filtration rise, but that on removal of the pressure a slow “recovery ” will 
take place. Deformation of the membrane, if simply tied over a tube, 
must also, unless it is properly supported, tend to distort channels and 
so increase resistance to filtration. To these sources of difference in the 
experiments must be added, previous drying of the membrane or not, 
the condition of imbibition of the fibrous tissue, and temperature 
variations. All these sources of differences are, moreover, accentuated 
by the fact that most of the experiments have been made with thick 
membranes, such as pericardium, bladder, intestine, and ureter. 

Nearly all who have studied filtration have found that at constant 
pressure the amount of the filtrate falls off with time,® but, as pointed 
out by Tigerstedt and Santesson,‘ this falling off is far more rapid in the 
earlier hours of an experiment than later, so that it is advisable in all 
such experiments on filtration to expose the membrane to pressure for 


' Meckel quoted by Ranke, ‘‘ Physiologie des Menschen; ” 1872, S. 122. 

* Cima, Mem. d. Accad. di Torino, 1853, vol. xiii. - Reid, Journ. Physiol., Cambridge 
and London, 1890, vol. xi. p. 312. 

3 Liebig, "© Untersuch. ii. einige Ursachen der Siftebewegung im thierischen Organismus,” 
Braunschweig, 1848, S. 7; Beitr. 2. Anat, w. Physiol. (Eckhard), Giessen, 1858, Bd. i. S. 
95 ; Runeberg, Arch. d. Heitk., Leipzig, 1876, Bd. xviii. S. 58 ; Gottwalt, Ztschr. J. physiol. 
Chem., Strassburg, 1880, Bd. iv. S. 423 ; v. Regéczy, Arch. f. d. ges. Physiol., Bonn, 1883 
Bd. xxx. S. 544. 

4 Bijhang. till k, Svens, Vet.-Akad., Stockholm, 1886, Bd. xi., No. 2. 


FILTRATION. 281 


many hours before the observations are conducted, and the stage of 
relatively constant rapidity of filtration (a uniform rate is never actually 
attained) is reached quicker at higher than at lower pressure. This 
phenomenon is not due to any stopping of pores by particles suspended 
in the fluids, since it is not noted when filtration is effected through 
unglazed porcelain, and is probably simply a result of compression of 
tortuous channels. 

The quantity of filtrate rises with the pressure, but in lower ratio. 

Thus, in an experiment by Tigerstedt and Santesson ? of filtration of 
distilled water through goldbeater’s skin (serosa of ox-gut), which had 
previously been exposed for 95 hours to a pressure of 80 cms. of water, 


| | 
| Filtrate per Minute |  Filtrate per Minute if 

= | Observed. proportional to Pressure. 
20 cm °046 grm. 046 grm. 

| | 
40 ,, 0381 ,, 092 ,, 
GOM 5; TORS. Lous 
0), ¢. 148 | "184 ,, 


The experiments of Wilibald Schmidt? showed a contrary result, 
ie. that the filtration rapidity increased at a higher ratio than the 
pressure (possibly due to using dried membranes, the pores of which 
were opened during experiment), as also did those of v. Regéczy. 

A period of rest, interpolated between two filtration experiments at 
the same pressure, is found to often cause an increase of the permeability 
of the membrane above the value it possessed at the time of dis- 
continuing the first experiment (Eckhard, Runeberg, Tigerstedt and 
Santesson). 

Thus Tigerstedt and Santesson,* in a filtration of distilled water 
through gold-beater’s skin at 40 em. pressure, observed a filtrate of 
‘490 orm. per minute, but after a resting period of 530’ the filtrate at 
the same pressure was ‘577 grm. per minute. But whether or not this 
phenomenon is observed, is probably due to whether or not the elastic 
limits of the fibres have been passed, “recovery” not being possible if 
the membrane has been excessively stretched. The interpolation of a 
period of filtration at lower pressure of course produces the same effect.° 

The rapidity of filtration rises with the temperature,’ and, according 
to Schmidt, the temperature coefficient is nearly that of Poiseuille, for 
the flow of fluids in capillary tubes. 

The nature of the solution to be filtered must obviously affect 
both the rapidity of filtration, from differences in viscosity, and also 
the quantitative composition of the filtrate in relation to that of the 
original solution. 

The following experiment from Tigerstedt and Santesson’ may be 
quoted in evidence of the first point :— 

1 Loc. cit., p. 31. 

2 Ann. d. Phys. wu. Chem., Leipzig, 1856, Bd. xcix. 8. 337 ; 1861, Bd. exiv. S. 337. 

3 Loc. cit. 4 hoe, CiteNa a: > Runeberg, doc. cit. 

6 Schmidt, Joc. cit. ; Eckhard, loc. cit. ; Lowy, Ztschr. f. physiol. Chem., Strassburg, 
1885, Bd. ix. S. 537. 

T Boe. cit.; p42. 


282 DIFFUSION, OSMOSIS, AND FILTRATION. 


1. Egg albumin—4'14 per cent. proteids ; pressure, 32°5 cm.; goldbeater’s skin. 
(Filtrate per minute in grms., 820, ‘051, 008, :008, 092, -002.) 
2. Ox serum—4'5 per cent. proteids ; pressure, 30°5 to 34 cm.; goldbeater’s skin. 
(Filtrate per minute in grms., 2°586, 1°594, 1000, °812.) 
In neither case had the membrane been previously stretched. 


According to Gottwalt,) the serum albumin of blood serum filters 
through a ureter more easily than the globulin. Martin? has shown 
that homogeneous membranes of gelatin and gelatinous silicic acid form 
filters impermeable to solutions of many colloids, but as permeable 
to certain crystalloids as to water. 

The relation of the concentration of the filtrate to that of the 
original solution is perhaps the most important point to the physiolo- 
vist in the matter of filtration through animal membranes. There is 
general agreement that in the filtration of erystalloids the concentration 
of the filtrate is very nearly that of the original solution, and this 
appears to obtain at very various filtration pressures.’ There is also 
general agreement that in filtration of colloids the concentration of the 
filtrate is “alway s less than that of the original solution. But as regards 
the effect of pressure on the concentration of a colloid filtrate, the 
results of different observers are not in accordance. Runeberg® has 
maintained that the concentration of the filtrate is higher at lower 
than at higher pressures, and the following table, taken front his later 
paper,® is illustrative :— 


Fresh Sheep’s Intestine—Ascitic Fluid (etrculated) holding 
3°72 per cent. of Proteids. 


Time Pressure in Cm. | Filtrate per hour | Per Cent. Albumin 
: of Fluid. in Grms. in Filtrate. 
8 P.M. to 8.15 A.M. : | ( 1°84 2°34 
8.15 A.M. to2.15 P.M. . |} 90 4 1°85 1°86 
2.15 P.M. to8.15p.m. . || \| 1:97 1:60 
8.50 P.M. to 8.50 A.M. . |) 30 | 1:29 2°02 
8.50 a.m. to 3.0 P.M. | 4 ee 1°52 DN, 
AO M 60) 7.30) P.M. . ||) 90 | 7°30 1°44 
7.30 P.M. to 9.30 A.M. . Jf \ 3°60 1°26 
10.15 A.M. to 2.15 P.M. . |) 30 { 2°89 2°42 
2°15 p.M. to 6.15 P.M. f \ 3°56 2°60 
7.0 p.m. to 9.30 P.M. \ 90 a 6°70 1:84 
9.30 p.m. to 8.15 A.M. J : \ 6°21 1°68 
1 Loc. cit. 2 Journ. Physiol., Cambridge and London, 1896, vol. xx. p. 364. 


* Schmidt, urea, sodic chloride, and potassium nitrate, Ann. d. Phys. u. Chem., 
Leipzig, 1861, Bd. cxiv. 8. 391. 

2 Schmidt, Joc. cit., gum and albumin through ox-pericardium ; Hoppe-Seyler, Virchow’s 
Archiv, 1856, Bd. ix. 8. 245, blood-serum ‘through ureter; Runeberg, Joc. cit., gut, 
ureter, ‘and pleural membrane, with serum, ascitic, and pleuritie fluids ; Gottwalt, Joc. cit., 
ege albumin, hydrocele fluid, serum, and parovarian cyst fluid through ureter. 

5 Loc. cit. 6 Zischr. fi physiol. Chem., Strassburg, 1882, Bd. vi. 8. 508. 


FILTRATION. 283 


On the other hand, the older experiments of Schmidt? with gum 
and albumin gave quite opposite results ; thus (p. 364 of 1861 paper)— 


Albumin through Ox Pericardium. 


. ets. Se. | 
Concentration of Original Per Cent. Albumin in Filtrate. 


Solution per Cent. Pressure. ‘Per Cent. Albumin in Original | 
| Solution. 

| 220 mm. 7037 

1°6 4 | 
| 120 mm. | 6638 

| 

( 220 mm. 7050 

3°5 4 
| 120 mm. “71742 


And the experiments of Gottwalt? and v. Regéczy * are in agreement 
with those of Schmidt. 

According to Lowy,* who filtered serum and egg albumin solutions 
through pig’s bladder at constant pressure, rise of temperature affects 
the quantity of the organic solids filtering more than the inorganic, and 
such slight temperature changes as from 37°°5 to 41°°5 C. have a distinct 
effect. 

It is therefore evident that our knowledge of the phenomena of filtra- 
tion through animal membranes is at present very restricted, and it is 
of course impossible to directly apply the results of the above observers 
to filtrations in the living body. No experiments, perhaps, have more 
clearly pointed out the difference between a dead and living filter than 
those of Tigerstedt and Santesson® with the frog’s lung. A fresh frog’s 
lung, filled with ‘6 per cent. sodic chloride solution, will stand a pressure 
of some 13 or 14 mm. of mercury without filtering for many hours ; 
heating in water at 54° C., or treatment with weak acetic acid, frog’s bile, 
weak sodic hydrate, or distilled w ater, at once, however (presumably by 
killing the cells), allows filtration. Leber? moreover, showed that the 
fresh cornea, provided the epithelium-of the membrane of Descemet is 
intact, will stand a pressure of 200 mm. of mercury, but at once 
allows filtration to occur when the epithelium is removed, the tissue 
of the cornea itself allowing fluid to pass. 

It must be confessed that experiments on living membranes (and 
these alone) can give any information of real value ; and, furthermore, it 
must be remembered that filtrations in the body are, as a rule, accom- 
panied by osmotic phenomena, since filtration must nearly always occur 
from one solution into another, and not into air, as in most experiments. 

In concluding this article,a word must be said with regard to the 
theory that in some cases the cells of a part take some active part in 
moving solutions across membranes. So little is known of cell mechanics, 
that if such a process does take place we have certainly no conception 
of its modus operandi, and it is at least probable that a process con- 
sidered to-day as a “vital action” may in the future: become capable 
of a simpler explanation. Certainly, if the same solution is placed on 


1 Loc. cit. 2 Loe. cit. 3 Loc. cit. 4 Toc. cit. > Loc. cit. 
6 Arch. f. Ophth., Leipzig, 1873, Bd. xix. Abth. 2, S. 125. 


284 DIFFUSION, OSMOSIS, AND FILTRATION. 


either side of a living membrane, and a current is found to pass from 
one side to the other, when the possibilities of filtration and electro- 
osmose are excluded, we have no physical explanation. Thus Heiden- 
hain! has demonstrated that serum is absorbed by the intestine. The 
pressure in the gut in relation to that in the capillaries, it is true, was 
not measured, and the serum was not the animal’s own serum, yet these 
objections are not of great force, especially the former, since an excess 
of pressure in the intestine would probably cause collapse of the capil- 
laries or venules.2 It is absurd to maintain that the motion of the 
blood in the capillaries aspirates the serum through the epithelium, 
because the rate of the blood stream is too slow to have any appreciable 
effect in this direction, and weak salt solution is moved across exsected 
and still living gut with equality of pressure on the two sides and no 
stream.® 

This class of absorption experiment appears to be the only one in 
which it is justifiable to speak of “vital action,” for differences in the 
ratios of “diffusion” of two substances into serum outside the body, 
and in the cavities thereof, are, per se, no proof of such action, since, as 
has been already indicated, the physical permeability of membranes 
differs much to one and the same substance ; and again, the fact that a 
drug affects the rate of absorption of a substance, after exclusion of the 
action of that drug (if any) on the circulation, is as well (and as little) 
explained by stating that the permeability of the membrane is altered 
by its combination with the drug, as by stating that the activity of the 
cells is affected. 

In spite of the magnificent labours of Dutrochet, Graham, Pfeffer, 
van ’t Hoff, and Arrhenius, the enigma of the physical chemistry of 
protoplasm in many cases still puts a limit to the physiologist’s concep- 
tion of the mode of motion of fluids through the membranes and cells 
of the body. 


1 Arch. f. d. ges. Physiol., Bonn, 1894, Bd. lvi. S. 579. 

2 The author has repeated Heidenhain’s experiment, using the animal’s own serum, and 
measuring the pressure in the gut, and in a mesenteric vein throughout. Active absorption 
occurs, of the water, of the organic, and of the inorganic solids of the serum, when the 
pressure in the gut is far below that in a mesenteric vein, and when all the lacteals leaving 
the loop have been hgatured. 

° Reid, Brit. Med. Journ., London, May 28, 1892. 


THE PRODUCTION AND ABSORPTION OF LYMPH. 
By Ernest H. STARLING. 


Contents.—The Production of Lymph, p. 285—-The Physical Forces concerned in 
the Movement of Lymph, p. 299—The Absorption of Lymph from the Con- 
nective Tissues, p. 302—On the Functions of the Lymph in the Nutrition of 
the Tissues, p. 310. 


THE PropucTioN oF LYMPH. 


THE spleen is the only part of the body where the blood comes in actual 
contact with the living cells of the tissue. In all other parts of the 
body the blood flows in capillaries with definite walls consisting of a 
single layer of cells, and is thus separated from the tissue elements by 
these walls and by a varying thickness of tissue. All the interstices of 
the tissues are filled with a fluid, lymph,! which thus acts as an inter- 
mediary between blood and tissues. The tissue spaces, which are filled 
with lymph, are always found in association with connective tissue. 
They have an incomplete lining of endothelial cells, and are connected 
with definite channels, lymphatics, by which any excess of fluid im the 
part is drained off. The lymphatics all run towards the chest, where 
those from the lower limbs as well as from the viscera join to form 
a large vessel, the receptaculum ehyli, which is continued into the 
chest as the thoracic duct. This runs on the left side of the cso- 
phagus, to open into the large veins at the junction of the left internal 
jugular with the subclavian vein. A small vessel on the right side 
drains the lymph from the right upper extremity and side of the 
chest. 

Lymph may be collected for examination by placing a cannula in 
one of the main lymphatics of a limb, and inducing a flow by move- 
ments of kneading and massage, from the lymphatic duct of the neck, or 
from the thoracic duct. Since, moreover, the serous cavities of the pleura, 
peritoneum, pericardium, and tunica vaginalis are in free communication 
with the lymphatic system, any fluid which is normally found in them 
may be looked upon as lymph. The various analyses of lymph that 
have been made, show that its composition may vary considerably 
according to the locality from which it is derived and the circumstances 
under which it is obtained. Certain general characteristics are, how- 
ever, common to all specimens of lymph. It is always slightly alkaline, 
and clots spontaneously at a variable time after it has left the vessels, 


1 Adler and Meltzer (Journ. Exper. Med., Baltimore, 1896, vol. i. No. 3) draw a sharp 
distinction between the interstitial fluid of the tissue spaces, and the lymph obtained from 
the lymphatics which drain these spaces. 


286 PRODUCTION AND ABSORPTION OF LYMPH. 


forming a colourless clot of fibrin. It contains from 2 to 8 parts 
per 100 of solids, of which about 1 per cent. consists of inorganic 
salts, while the rest is made up chiefly of proteids. The proteids are 
similar to those of the blood plasma; and it seems that the process of 
clotting is identical in the two fluids. The salts vary very little in 
different samples of lymph, and are generally described as being present 
in exactly the same proportions as in the blood plasma from which the 
analysed specimen of lymph was derived. Hamburger has recently 
called attention to the existence of minute differences of composition in 
the salts of the two fluids, and this difference may be credibly ascribed 
to chemical changes effected in the lymph by the tissues over which it 
has flowed. All specimens of lymph contain leucocytes, chiefly of the 
small uninuclear variety; these are found in greater numbers after the 
lymph has passed through a lymphatic ¢ eland. Further information re- 
garding the composition of lymph will be found in the article on lymph 
and serous exudations (p. 180). 

The similarity in composition between liquor sanguinis and lymph 
suggests that the latter may be regarded as part of ‘the plasma which 
exudes through the capillary wall, bathes all the tissue elements, and is 
collected by the lymphatics into the thoracic duct to be returned again 
to the blood. 

Forces involved in lymph production.—Older theories.—As to 
the forces involved in its production and the use of this fluid in the 
functions of the body, the most various views have been held. Asellius,? 
who discovered the lacteals in 1622, thought that these ducts 
carried the foodstuffs from the intestines to the liver to be there 
elaborated into blood. In order to explain the filling of the lacteals 
from the intestines, Asellius invoked the aid of the complicated 
mechanism which had already been imagined by Avicenna to account 
for the filling of the mesenteric veins. “He explained the passage of 
chyle to the liver as due ake to the intestinal movements and partly 
to the suction-action of the blood vessels and of the liver itself. The 
chief factor however was, according to him, the suction-action exerted 
by the open mouths of the lacteals themselves, and he compares the 
latter to leeches, which suck blood from any surface to which they are 
appled. This theor y was overthrown by Pecquet? by the discovery of 
the connection of the lacteals with the thoracic duct and through this 
with the venous system. The general lymphatics were discovered 
by Rudbeck* and Bartholin # almost simultaneously. In these authors 
we meet with the first conception of lymph apart from absorbed 
foodstuffs ; moreover, Bartholin, assuming that this lymph is formed 
from the blood, discusses the possible ways by which the fluid could 
get from blood vessels to lymphatics. He thinks it possible that 
there may be a direct communication between lymphatics and blood 
vessels, but is more inclined to the view that the communication is 
indirect by means of the parenchyma of the organs. Failing to remark 
what Rudbeck had already noticed, namely, that the lymph had a salt 
taste, and like blood clotted spontaneously, he describes the lymph as 
pure water, and imagines that from the blood vessels there is a 


** De lactibus sive lacteis venis,” Basel, 1628. 

‘* Experimenta nova anatomica,” Paris, 1654. 

** Nova exercitatio anatomica, etc.” 1653. 

‘Vasa lymphatica nuper in animantibus inventa,” Hafnie, 1653. 


me OD 


THEORY OF LUDWIG. 287 


transudation of water carrying solids in solution, the solids being taken 
up by the tissues, and the pure water which is left over returned by 
the lymphatics to the blood. We get here the first conception of the 
irrigation theory of tissue nutrition which has played so great a part in 
the “speculations of later physiologists. 

With Hunter! and Monro? we find a return to the older theory, that 
lymph was produced by a process of suction. This indefinite conception, 
however, allowed a considerable degree of individual licence as to the 
details of the process, and important authors, such as Hunter and 
Mascagni,’ recognised the possibility of a simple transudation or filtra- 
tion through the blood-vessel walls. This latter view, however, did not 
meet with general recognition, physiologists preferring to believe 
in the existence of the exhalant arteries which no one had yet seen 
or was ever going to see. Thus we find Bichat* definitely asserting 
the existence of “vasa exhalantia.” Speaking of connective tissues, he 
writes: “Chaque cellule du tissue cellulaire est un réservoir inter- 
meédiare aux exhalants, qui sy terminent, et aux absorbants qui en 
naissent.” The absorption through the supposed open mouths of the 
lymphatic and lacteal vessels was attributed by most authorities of this 
time to capillary attraction, while the onward flow of the fluid in the 
lymphatics could, according to Cruickshank, only be explained as due 
to the vital activity of living cells or tissues. Haller describes the 
movement of the chy le from the intestines in exactly the same manner. 
Particularly ingenious is Hewson’s® explanation of the absorption and 
movement of chyle i in the lacteals. He shows that during life the blood 
vessels of the villi and in the papille of the skin and mnucous mem- 


_brane, by their turgescence, keep the orifices of the lacteals or the similar 


openings of the lymphatics patent, so that these are now capable of 
attracting like capillary tubes made of hard substances. The further 
movement of the chyle and lymph he ascribes to the peristaltic con- 
traction of muscular fibres in the walls of the lacteals or lymphatics. 

Views very similar to these were held by some of the most dis- 
tinguished of subsequent physiologists, such as Prochaska, Fohmann, 
Burdach and Henle. In opyoutnes to this mechanical theor y of lymph 
formation, Johannes Miiller,° having regard to the apparent power of 
choice possessed by the lacteals, some substances being absorbed while 
others were left, was inclined to ascribe at any rate the act of absorption 
to the vital mien of the living cells of the body. 

On the discovery of endosmosis by Dutrochet,7 many physiologists 
believed that at last the riddle of absorption and secretion of lymph was 
solved, and from this time onwards we find an invocation, generally 
more or less vague, of osmotic action to explain the phenomena of 
absorption and secretion. 

Theory of Ludwig.—The beginning of the new era in the history 
of the physiology of lymph formation is marked by the important 
paper of Ludwig and Noll8 In consequence of experiments on 


1 Works, edited by Palmer, London, | 1835, vol. iv. p. 299. 

** De venis lymphaticis valvulosis,” 1757. 

**Vasorum lymphaticorum corporis humani historia et iconographia,” 1787. 

** Anatomie générale,” 1812. 

** A Description of the Lymphatic System, ete.,” Collected Works, Syd. Soc., 1846. 

6 «*Klements of Physiology,” Baly’s trans., 1838, vol. i. p. 248. 

7 Previous article, p. 273. Seealso ‘‘ Cyclopedia of Anat. and Phys.,” art. ‘‘ Endosmose.”’ 
8 Zischr. f. rat. Med., 1850, Bd. ix. S. 52. 


co em © bo 


288 PRODUCTION AND ABSORPTION OF LYMPH. 


blood pressure, carried out by the aid of the mercurial manometer of 
Ludwig, these authors concluded that the chief factor in the forma- 
tion of lymph was the pressure of the blood in the capillaries, and 
that in fact the lymph was essentially only the fluid part of blood 
which had filtered through the vessel wall into the surrounding 
tissues. On arriving in the tissues, this lymph or blood filtrate was 
still under a certain pressure, derived from the blood pressure, and 
it was this pressure which occasioned the movement of the lymph 
into and along the lymphatics. Ludwig concluded that the flow and 
composition of the lymph must be explained not only by filtration 
of the fluid parts of the blood, but also by processes of osmosis taking 
place between the tissue juices and the blood. He summarises his theory 
in the following words :—* The blood which is contained in the vessels must 
always tend to equalise its pressure and its chemical constitution with 
those of the extravascular fluids, which are only separated from it by the 
porous blood-vessel walls. If, for example, the quantity of blood in the 
vessels has increased, the mean blood pressure is also increased, and at 
once a portion of the blood is driven out into the tissues by a mere 
process of filtration. The same result is brought about when the con- 
stitution of the blood is altered by the absorption of food or by increased 
excretion by the kidneys, blood, or skin, or when the composition of the 
tissue fluids is altered in consequence of increased metabolic changes 
taking place in the tissues. In the latter case, the changes brought 
about in the lymph are effected by processes of diffusion.” Since it is a 
condition of the maintenance of life that these chemical changes in the 
tissues should go on, and that the waste products should be continually 
excreted by the kidneys, lungs, and skin, there must be at the same 
time constant changes in the amount and composition of the lymph 
produced.? 

The testing of this, the mechanical theory of lymph formation and 
the lineal descendant of the theory propounded two hundred years 
previously by Bartholin, has been the object of all subsequent investiga- 
tions dealing with this question. Although we cannot claim to have 
arrived at a final decision on the matter, I shall endeavour to show in 
the following pages that the two processes—filtration and diffusion— 
described by Ludwig, will probably account for the lymph flow and 
composition in all the cases which have been sufficiently investigated. 

It was shown many years ago by Magendie and others, that chemical 
differences between blood and lymph provoked a transference of the 
substance that was in excess from one side of the vessel wall to the 
other. Thus, if colouring matters, salts, or sugar be injected into the 
blood, they are very shortly afterwards found in the lymph in various 
parts of the body. If, on the other hand, these substances be injected 
into the tissue spaces or into the pleural or peritoneal cavities, their 
existence can very soon be detected in the blood, whence they make 
their way into the urine. Other instances of the extreme rapidity with 
which osmotic interchanges take place between the blood and lymph 
will be mentioned later on in dealing with the action of lymphagogues. 
Since these interchanges take place after the introduction of abnormal 
as well as normal substances into the body, we must assume the general 
applicability of the results, and look upon processes of diffusion or 
osmosis as one of the factors in regulating the composition of the lymph. 

1“ Tehrbuch der Physiologie,” 1861, Aufl. 2, Bd. ii. S. 562. 


THEORY OF HEIDENHAILN. 289 


Not so successful were Ludwig’s attempts to demonstrate a direct 
relationship between blood pressure and lymph formation. According 
to Ludwig’s hypothesis, the amount of lymph produced in any given 
part must be proportionate to the difference between the pressure in 
the capillaries and the pressure in the extravascular spaces. In most of 
Ludwig's earlier experiments on the subject this condition was found to 
hold good. On leading defibrinated blood through a limb, the lymph 
production in the limb was found proportional to the pressure at which 
the blood was led through it. In the testis Tomsa! showed that ligature 
of the pampiniform plexus caused a large increase in the lymph from 
this organ. Paschutin? and Emminghaus* found that, in the arm and 
leg, extensive ligature of the veins led to an increased lymph production. 
In all these cases, therefore, an augmented flow of lymph was obtained 
by raising the capillary pressure of the part. On the other hand, the 
two last-named observers were unable to prove any constant alteration 
of lymph production incident on vasomotor changes. Thus, in one 
experiment, Paschutin divided the brachial plexus of a dog and then 
stimulated the cut spinal cord, so that there was constriction of all the 
arteries of the body with the exception of those of the fore-limb under 
observation. Even this rise of pressure had no effect on the lymph flow 
from the fore-limb. A little later, Rogowicez,t working in Heidenhain’s 
laboratory, repeated Emminghaus’ experiments on the hind-limb with 
slight alterations, and found almost invariably a slight increase in the 
lymph after section of the sciatic nerve or in consequence of active vaso- 
dilatation. He proved, moreover, that the vaso-dilatation of the tongue 
produced by excitation of the lingual nerve was followed by an increased 
lymph production in the tongue, which might at times amount to an 
actual unilateral cedema of this organ. 

Theory of Heidenhain.—In dealing with the laws affecting 
lymph production, we are hampered by the fact that, from the limbs 
of an animal at rest, there is, under normal conditions, no lymph flow 
at all, so that, when we wish to study the effects of our various 
procedures on the lymph production in the limb, we have artificially 
to bring about a lymph flow by kneading and massaging the limb. 
This fact introduces at once an arbitrary element into the observa- 
tion, and Heidenhain suggested, therefore, that the best mode of 
investigating the truth of the filtration hypothesis would be to 

experiment on the lymph flow from the thoracic duct. This physio- 
logist carried out a long research on the various conditions under 
which the lymph flow from the thoracic duct might be increased 
or diminished,> and came to the conclusion that the results of his 
experiments were irreconcilable with the filtration doctrine, and that we 
must assume that the cells forming the walls of the capillaries take an 
active part in lymph formation, ze. that lymph must be looked upon as 
a secretion rather than as a transudation. A very similar conclusion had 
been previously arrived at by Tigerstedt,® mainly on theoretical grounds. 

Heidenhain’s arguments may be shortly summarised as follows :— 

1. Obstruction of the thoracic aorta causes a general fall of arterial 


1 Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1862, Bd. xlvi. S. 185. 

2 Arb. a. d. physiol. Anst. zu Leipzig, 1873. % Tbid., 1873. 
4 Arch. f. d. ges. Physiol., Bonn, 1885, Bd. xxxvi. 8. 252. 

5 Tbid., 1891, Bd. xlix. S. 209. 

8 Mitth. a. d. physiol. Inst. zu Stuckholm, 1886. 


VOL. I.—19 


290 PRODUCTION AND ABSORPTION OF LYMPH. 


blood pressure below the obstruction. In spite of this fact, the lymph 
flow from the thoracic duct may in some cases be unaltered and even 
slightly increased. 

2. Obstruction of the inferior vena cava above the diaphragm causes 

a general fall of blood pressure, and the intestines become apparently 
anemic. The lymph flow from the thoracic duct is largely increased, and 
the lymph undergoes chemical changes, becoming more concentrated 
than it was before the obstruction. This lymph, according to Heiden- 
hain, comes from the intestines, whereas, on obstruction of the portal 
vein, these organs yield an increased flow of a lymph which is less 
hacen than normal and contains red blood corpuscles, 

Heidenhain describes two classes of bodies, which on injection 
ae the circulation increase the lymph flow from the thoracic duct. 

The first class comprises bodies such as commercial peptone, watery 
extract of dried leeches or of crayfish. These increase the lymph and 
make it more concentrated. They usually cause a lowering of arterial 
blood pressure, although by careful injection this may be avoided. 

The second class includes crystalloids such as sodium chloride, sugar, 
etc. Injection of concentrated solutions of these bodies into the circula- 
tion evokes an increased flow of lymph which is less concentrated than 
before. Some time after the injection, it is found that the lymph 
contains a greater percentage amount of imjected substance than does 
the blood plasma. There may be a slight rise in the arterial pressure, 
but this rise is in no way proportionate to the augmentation in the 
lymph flow. 

Since, therefore, the lymph flow may be increased without any 
corresponding elevation in the blood pressure, and since the amount of 
injected substance in the lymph may rise above that in the blood plasma, 
Heidenhain concludes that the processes of filtration and diffusion are 
incapable of accounting for the changes observed in the amount and 
composition of the lymph; although he does not deny that, under certain 
pathological conditions, such as heart disease and cirrhosis of the liver, 
dropsy or ascites may be and probably is conditioned by the increased 
intracapillary pressure acting in many cases on a capillary wall already 
weakened and abnormal in consequence of anemic and diseased states 
of the blood. 

Comparison of the theories of Ludwig and Heidenhain. — A 
renewed examination! of Heidenhain’s experiments, combined with a 
more thorough investigation of their conditions, has persuaded me that, 
so far from overthrowing the filtration hypothesis, they furnish the 
strongest arguments which have yet been adduced in its favour. I may 
therefore give some account of these experiments, and show how they 
support Ludwig’s contention with regard to the production of lymph. 

Sources of the lymph investigated. —In dealing with the lymph flow 
from the thoracic duct, it is essential to know from what parts of the 
body this lymph is derived, especially since, as is well known, the 
lymphatics from all parts of the body, with the exception of the 
right upper extremity and right side of the neck, converge to pour 
their contents into this duct. In placing a cannula in the duct, 
in order to collect and measure the lymph, the ducts from the left 
side of the neck and left upper extremity are ligatured. From the 


1 Bayliss and Starling, Jowrn. Physiol., Cambridge and London, vol. xvi. p. 159 ; Star- 
ling, ibid. vol. xvi. p. 224, and vol. xvii. p. 30. 


THEORIES OF LUDWIG AND HEIDENHAIN. 291 


hind-limbs we know that, in an animal at rest on the table, there is no 
lymph flow at all. Hence the sources of the lymph are confined to the 
trunk. We can, moreover, exclude the thorax and its contents, since 
ligature of the thoracic duct just above the diaphragm absolutely stops 
the lymph flow. Therefore, when dealing with the lymph flow from the 
thoracic duct, we deal only with the ly mph coming from the abdominal 
viscera. As I shall show presently, the abdominal viscera, so far as their 
lymph is concerned, may be divided into two sroups—(1) the viscera 
drained by the portal vein, and (2) the liver. 

Influence of venous obstruction—In testing the filtration hypothesis 
on the lymph flow, we have to investigate whether the flow is always 
proportional to the difference between the intra- and extracapillary 
pressures. We may regard the extracapillary pressure as not varying 
to any large extent, so that we have to see what effect is produced 
on the ly ‘mph by variations im the imtracapillary pressure in the 
intestines and the liver. The simplest experiments on the subject 
are those in which some large vessel is obstructed. Speaking generally, 
we may say that obstruction of a large vem raises the pressure in 
the capillaries immediately behind it, whereas obstruction of an 
artery will diminish the pressure immediately in front of it. If, 
for instance, we ligature the portal vein, the arterial pressure is very 
little affected, while the pressure in the vein behind the ligature 
rises enormously. In consequence of this, there is a large rise of 
pressure in the capillaries of the intestines and spleen, so that the 
spleen swells and the intestines become black from venous congestion, 
hemorrhages being produced into their mucous membrane. The effect 
of this igature on the lymph flow from the thoracic duct is to increase 
it four or five times. The lymph also becomes bloody and its total 
solids are diminished. The diminution in solids is due solely to a 
diminution in proteids, the salts remaining the same as before; so that 
we have here an increased capillary pressure, causing an increased trans- 
udation of lymph containing a diminished percentage of proteid—a result 
which is also obtained when proteids are filtered with pressure through 
dead animal membranes. The presence of red blood corpuscles in the 
lymph is not a necessary consequence of a rise of pressure in the 
portal vein. If a less excessive rise of pressure be produced by 
ligaturing the vein, not at its entry into the liver but just below the 
pancreatico-duodenal vein, thus leaving a circuitous route for the blood 
to the liver through the anastomoses of this branch, an increased flow 
of lymph is produced, containing less proteids than normal lymph, 
but which may be quite free from red blood corpuscles. 

Still more striking is the effect produced by Heidenhain’s experi- 
ment of obstructing the vena cava just above the diaphragm (ie. 
between the opening of the hepatic veins and the heart). The lymph 
is increased from ten to twenty fold, and it is found that the lymph 
obtained after the obstruction is free from red blood corpuscles and is 
more concentrated than normal lymph. Thus, in one experiment of 
this description, the lymph flow rose from 5 c.c. in the ten minutes 
preceding the obstruction to 25 c.c. in the ten minutes after the vein was 
oceluded. At the same time the percentage of solids in the lymph rose 
from 4°8 per cent. before, to 6°6 per cent. after the obstruction. 

What is the cause of this increased lymph flow and why is it more 
concentrated? To answer these questions we must find out first, the 


292 PRODUCTION AND ABSORPTION OF LYMPH. 


source of the lymph, and secondly, the condition of the capillary 
pressure in the organ or organs from which the lymph is derived. We 
can determine the source of the lymph by a process of exclusion. 
Tying the kidney vessels and lymphatics has no effect on the usual 
consequences of obstructing the inferior vena cava. On the other 
hand, if we ligature the lymphatics in the portal fissure which carry 
off the liver lymph, we find that a subsequent obstruction has no effect 
on the lymph flow, or indeed, may slightly diminish it. We must 
conclude that the excess of lymph production consequent upon the 
obstruction is entirely derived from the liver, and not, as Heidenhain 
thought, from the intestines. The change in concentration is easily ex- 
plained if we assume that, just as intestinal lymph is more concentrated 
(z.e. richer in proteids) than the lymph from the limbs, so the liver 
lymph is more concentrated than intestinal lymph, or than the mixed 
lymph obtained from the thoracic duct. 

In order to answer the question as to the cause of this increased 
production of lymph in the liver, we must investigate the changes in 
the circulation brought about by the obstruction. On obstructing the 
inferior vena cava and recording the blood pressure in the chief vessels 
of the abdomen, we notice that the pressure in the aorta drops almost 
at once to a third of its previous height, whereas there is a very 
considerable rise of pressure both in the portal vem and inferior cava. 
It is probable that the effect of the rise of portal pressure on the 
intestinal capillaries is more than counterbalanced by the severe drop 
in arterial pressure, so that there is a fall of pressure in the intestinal 
capillaries. This conclusion is borne out by the fact that, if the 
abdomen be open, the obstruction of the inferior vena cava is seen to be 
at once followed by blanching of the intestines, as Heidenhain pointed 
out. On the other hand, the effect of the simultaneous rise of pressures 
in the portal vein and vena cava must be to increase the pressure in 
the capillaries of the liver to three or four times the normal amount. 
We have then, as the results of this experiment, no rise of pressure in 
the portal area and no increase of lymph flow from the portal area, a 
large rise of pressure in the hepatic capillaries and a very large 
increase of lymph flow from the liver. 

Influence of aortic obstruction— Another experiment, on which 
much stress has been laid by Heidenhain, is the one in which 
the descending aorta is obstructed in the thorax. The obstruction 
of this vessel is easily effected by passing an indiarubber balloon, 
tied on the end of a catheter, down the right carotid artery into 
the aorta just beyond the arch. The results of this obstruction on 
the lymph flow are somewhat variable. In most cases the lymph is 
diminished to one-half or one-third its previous amount; in a few 
cases the lymph is unaltered in quantity or even slightly increased. 
In all experiments the amount of proteids in the lymph is increased. 
Now, if we investigate the state of the circulation under these con- 
ditions, we find that obstruction of the thoracic aorta causes a very 
considerable fall of pressure in the aorta below the obstruction and 
a corresponding fall in the portal vein, whereas the pressure in the 
inferior vena cava is unaltered or in some cases even slightly increased. 
We must conclude, therefore, that in the intestinal capillaries the 
pressure has fallen considerably below its normal limits, while in the 
hepatic capillaries the pressure is very little altered or may even be 


THEORIES OF LUDWIG AND HEIDENHAIN. 293 


somewhat increased. Hence the only region of the body below the 
point of obstruction where the capillary pressure is not much diminished 
is the liver. Now we find that the liver is also the sole source of the 
lymph obtained under these circumstances. If the hepatic lymphatics 
be ligatured, and the thoracic aorta be then obstructed, the flow of 
lymph from the thoracic duct is absolutely stopped. 

These three experiments show, therefore, that the lymph production 
in the organs of the abdomen is directly proportional to the capillary 
pressure in these organs, and not independent of them, as was imagined 
by Heidenhain. 

Hydremia and hydremie plethora.—In another series of experi- 
ments we find, as was predicted by Ludwig (cf. p. 288), that a marked 
increase in the lymph flow is produced by a general rise of capillary pres- 
sure in all the organs of the abdomen. Such a general rise of capillary 
pressure may be brought about by the injection of large quantities 
of normal saline fluid into the circulation, thus causing a condition of 
hydremic plethora. Under such circumstances the lymph may be in- 
creased from fifty to one hundred times in amount, and may in some 
cases run from the cannula in the duct in a steady stream. Now, in 
hydrzemic plethora there are two changes in the circulation which might 
possibly be responsible for the increased production of lymph—first, 
the change in the composition of the blood, and secondly, the increased 
pressure in the capillaries of the abdominal viscera. We can decide 
which of these two factors is responsible for the increased lymph flow 
by a very simple experiment. Previously to injecting 300 c.c. of normal 
saline, we bleed the dog to 500 «c., so that after the injection the total 
amount of circulating fluid is the same as at the beginning of the 
experiment. In this way we entirely avoid any rise of capillary 
pressure, while we have diluted the blood to an even greater extent 
than in the experiments in which hydremic plethora was produced. 
The effect of such a simple hydremia is to increase the lymph flow 
from 3 cc. in ten minutes to 4 or 6 cc. in ten minutes; whereas, if 
hydremic plethora were produced, the lymph would be increased from 
3 ec. to 30, 50, or 100 «ec. in ten minutes. It is evident, therefore, that 
in the production of this increased lymph flow the all-important factor is 
the rise of capillary pressure; although the slight increase in the lymph 
flow observed as the result of simple hydrzmia shows that, as might be 
expected, a watery plasma gives rise to a transudation of lymph more 
Sa does the normal more concentrated plasma. 

eidenhain’s second class of lymphagogues—tIn a precisely similar 
manner we may explain the mode of action of the substances which 
were described by Heidenhain as the second class of lymphagogues. 
These include bodies such as salt, sugar, potassium iodide, ete. The 
injection of a strong solution of dextrose (50 grms. in 30 ¢.c. water) into 
the veins of an animal causes a considerable increase in the lymph flow 
from the thoracic duct. The lymph at the same time becomes more 
watery than at the commencement of the experiment. Heidenhain 
ascribes this effect to a specific excitation of the secretory activities of 
the endothelial cells. The effect, however, can be explained in a much 
more simple fashion. All these solutions have an osmotic pressure 
which is considerably higher than that of normal blood plasma. <A 
solution of dextrose that should be isotonic with the blood plasma would 
contain from 5 to 6 per cent. of this body. When we inject a solution 


294 


PRODUCTION AND ABSORPTION OF LYMPH. 


containing from 50 to 75 per cent. of dextrose, it will attract fluid from 


the tissues until its percentage 
is reduced to 5 or 6 per cent. ; 


that is to say, 45 ce. of fluid 


containing 30 grins. of dextrose 


will attract water from the tissues 


until its total volume is increased 


to 500 ee. Of course this esti- 


mate is merely a rough approxi- 


mation at the truth, since before 
the sugar has had time to attract 


100 


lo 5 A 5' 10! 


Fic. 40.—Diagram to show the dilution of the 


15’ 20’ 25’ 30’ 35’ 40! 45’ 50! 


all this fluid, a considerable 
amount of it will already have 
left the vessels by diffusion. As 


blood (¢.e. hydremic plethora) produced in 
dogs (Experiments 1, 2, 3, 4) by the injec- 
tion of 5 grms. dextrose per kilo. body- 
weight. The ordinates represent the 
volume of the blood (compared with the 
normal) as indicated by percentage of 
hemoglobin. The abscissze represent inter- 
vals of five minutes. The line AA, marks 
the time at which the injection was finished 
in each experiment. The dotted lines to 
the left of AA, indicate the theoretical dilu- 
tion effected by the volume of fluid injected. 


a matter of fact, however, we find 
that injection of a strong solu- 
tion of dextrose is followed in a 
few minutes by a considerable 
dilution of the blood, caused by 
an increase in its volume. In 
some experiments of von Brasol, 
the volume of the circulating 
blood was thus increased to twice 


—After J. B. Leathes. 


have been fully confirmed im a series 


J. B. Leathes? (Fig. 40). 


or three times its previous 
amount; and these observations 
of careful experiments made by 


As we should expect, 
this increase in the vol- 45 
ume of the circulating 4, 
blood is attended by a 
large rise of capillary ~ 
pressure in the abdomi- *° 
nal viscera (Fig 41), and 2s 
we have here again to 4 
decide whether it is this 
rise of capillary pressure, 
or the change in the " 
chemical composition of 5 
the blood,that determines — , 
the increased lymph flow. °L§ '° ies aides zt 800 


This question can be 
solved by using the same 
method that we adopted 
when dealing with the 
production of the in- 
creased lymph flow in 
hydrzmic plethora. We 
can entirely obviate the 
rise of capillary pressure 


——o 


Inj. of 40 grams dextrose 


if we bleed first to 300 e.ec. 


1! Arch. f. Physiol., Leipzig, 1884, S. 211. 
* Journ. Physiol., Cambridge and London, 1895, vol. xix. p. 1. 


Fic. 41.—To show influence of the intravenous injection 


of dextrose on the blood pressure in the abdominal 
viscera, and on the lymph flow from the thoracic duct. 
The upper dotted line= pressure in portal vein. The 
lower dotted line=pressure in inferior vena cava. 
The thick continuous line=pressure in aorta. The 
thin continuous line=lymph flow. The ordinates 
represent venous pressure in centimetres of water, 
arterial pressure in centimetres Hg, and lymph flow 
in cubic centimetres per ten minutes. 


and then inject a concentrated solution 


THEORIES OF LUDWIG AND HEIDENHAIN. 295 


containing 18 grms. of dextrose (Fig. 42). In this case the fluid that 
is dragged by the sugar from the tissues into the blood vessels only 
just suffices to make up for the previous loss of blood. No hydrzemie 
plethora is produced; there is no rise of capillary pressure, and there 
is no increase in lymph flow, although an abnormally large amount 
of dextrose is present in the circulation. 

The fact that the immediate agent in the production of the increased 
lymph flow is the hydre- 
mic plethora which suc- 
ceeds the injection, explains 
the point noticed by Heid- f= p= 
enhain, that the efficacy °_5 ©, 20 30 40 50 — GOminutes 
of these substances is di- 240 com. (grams dextrose 


rectly proportional to their Fic. 42.—To show absence of effect of injecting dextrose 
attraction for water ( }Ias- after a previous bleeding. The description of the 
. curves in Fig. 41 also applies to this figure. 


seranziehungsvermogen), 7.2. 
to the osmotic pressure of the solution injected, and is therefore a 
function of their molecular weights. A similar relation was noticed 
by von Limbeck! to hold for the diuretic action of these bodies, which 
may therefore also be possibly determined directly by the hydremic 
plethora. 

The advocates of the secretory hypothesis have laid great stress on 
the fact that if we analyse the lymph and the blood at different periods 
after the injection of sugar, we find that the amount of this substance in 
the blood steadily diminishes (even when the kidneys are cut out of the 
circulation), while the sugar in the lymph gradually rises to a maximum 
and then diminishes parallel with but above that in the plasma. This 
was found to hold good for sugar by Heidenhain, for potassium iodide 
by Ascher,? and for commercial peptone by myself* We are not, how- 
ever, justified in concluding from these facts that the sugar, etc., have 
been turned out from the blood vessels against pressure, so to speak. 
As Cohnstein® has pointed out, the lymph flowing at any given moment 
from the thoracic duct does not represent the transudation from the 
blood at that moment, but is derived from the lymph that has been 
formed some time previously. If we had a solution of sugar in gradually 
diminishing strength flowing into a lymphatic trunk of the leg, it is evident 
that this fluid would mix with the lymph in the other lymphatics, through 
which it flowed on its way to the thoracic duct. Later, the solution of 
sugar would have displaced practically all the lymph from these channels, 
and would flow through the thoracic duct almost undiluted. It would 
take, however, some considerable time to flow from the leg to the 
thoracic duct, so that the outflow from the duct would represent, not the 
fluid which was being injected into the leg at that moment, but the 
stronger solution which had been flowing in some time previously. If 
one compared, therefore, the percentage of sugar in the fluid flowing 
from the duct and in the fluid flowing into the leg lymphatic at different 
times after the beginning of the injection, we should obtain a curve 
exactly similar to those obtained by Heidenhain after the injection of 
sugar into the circulation, and regarded by him as undeniable evidence 


1 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1888, Bd. xxv. S. 69. 

2 Loc. cit. ° Ztschr. f. Biol., Miinchen, 1893, Bd. xxix. S. 247. 
4 Starling, Journ. Physiol., Cambridge and London, 1893, vol. xiv. p. 131. 
5 Arch. f. d. ges. Physiol., Bonn, Bd. lix. 8. 350. 


296 PRODUCTION AND ABSORPTION OF LYMPH. 


of secretory activity. We may conclude, therefore, that the increased 
flow of lymph caused by injection of the second class of lymphagogues 
is entirely due to the rise of capillary pressure thereby induced, and is in 
no wise conditioned by a stimulation of the secretory activities of the 
endothelial cells. 

The permeability of the capillary wall—The dependence of lymph 
formation on capillary pressure is not the only important relationship 
brought to light by these experiments. The amount and composition of 
the transudation through a membrane depend not only on the pressure 
at which the transudation is effected, but also on the nature of the mem- 
brane. According to the permeability of the membrane, so the amount 
and composition in proteids of the transuding fluid will vary. After 
obstruction of the inferior vena cava, the pressure in the intestinal capil- 
laries, although it probably sinks below its normal height, is yet as high . 
as that in the hepatic capillaries. Nevertheless, we get a very small 
amount of transudation through the intestinal capillaries, and a very large 
amount through the hepatic capillaries. Hence the permeability of the 
liver capillaries must be very much more marked than that of the intestinal 
capillaries. In the same way we may compare the permeability of the 
intestinal capillaries with those of the limb capillaries. Normally from 
the limb there is no flow of lymph at all, whereas a probably equal 
pressure in the intestinal capillaries suffices to give rise to a steady flow 
of lymph. If we leature all the veins of the leg, a lymph flow may be 
set up, but such a flow is incomparably smaller than that produced on 
ligature of the portal vein. We can therefore arrange the capillaries of 
the body in a descending order of permeability, the liver capillaries being 
the most permeable and the limb capillaries the least permeable. I have 
already mentioned how, on filtering solutions of proteid through various 
membranes, the percentage of proteids in the filtrate increases with the 
permeability of the membrane. As we have seen, exactly the same 
thing holds good for the capillaries in the body. The lymph in the 
limbs, the filtrate through the impermeable limb capillaries, contains 
only from 2 to 3 per cent. proteids; that from the intestines contains 
from 4 to 6 per cent. proteids; while that from the permeable capillaries 
of the liver contains from 6 to 8 per cent. proteids—in fact, almost as 
much as the blood plasma itself. It is conceivable that we might alter 
the amount of lymph in any organ by changing, not the intracapillary pres- 
sure, but the filtering membrane, 7c. the endothelial wall of the capillaries. 
Such a change can be brought about in the body by various means. 
Thus the permeability of the limb capillaries is considerably increased as 
the effect of any local injury, such as that caused by plunging the limbs 
into water at 56 C. for a few minutes. Cohnheim! pointed out that if a 
cannula be placed in one of the lymphatics of the foot, and the foot be 
then scalded in this manner, in a few minutes the lymph begins to flow 
spontaneously from the cannula. The lymph which is thus produced is 
much richer in proteids than is lymph from a normal limb. Moreover, 
as Jankowski? showed, the amount of lymph flowing from the foot can 
now be varied within wide limits by altering the pressure in the capil- 
laries, either by ligature of the vein or artery, injection of salt solution, 
or production of vasomotor paralysis. By this scalding, in fact, we may 
reduce the limb capillaries to the condition of liver capillaries. 


1 Virchow’s Archiv, 1877, Bd. lxix. S. 516. 
* Ibid., 1883, Bd. xciii. 8. 259. 


THEORIES OF LUDWIG AND HEIDENHAIN. 297 


Heidenhain’s first class of lymphagogues.—W e are now in a position to 
discuss the mode of action of the animal poisons included in the first 
class of lymphagogues. On injecting a decoction of crayfish, leeches, or 
mussels into the blood, the lymph flowing from the thoracic. duct is 
increased in amount, and becomes much more concentrated than before. 
In both blood and lymph coagulability is lessened or abolished; the 
blood becomes more concentrated from a loss of plasma, while the 
plasma itself is less concentrated than before the injection. The blood 
pressure, though generally lowered, may be unaltered if the injection be 
carefully carried out; the heart-beat is always quickened. Heidenhain 
concludes that these bodies exert a specific influence on the endothelial 
cells, causing them to secrete an increased amount of lymph more con- 
centrated than the blood plasma. 

There can be no doubt that the greater concentration of the lymph 
obtaied under these circumstances is due to the fact that it is chiefly 
derived from the liver, since the effect of these lymphagogues on the 
lymph flow may be almost abolished, if the portal lymphatics be liga- 
tured previous to the injection. On investigating the changes in 
capillary pressure consequent on the injection, | have found that they 
are not sufficient to account for the increased lymph production. It is 
true that injection of one of these bodies is invariably followed by a con- 
siderable rise of pressure in the portal vein, associated with general 
vascular dilatation. But this rise of pressure is comparatively transitory 
(Fig. 45), lasting only fifteen to forty minutes, whereas the increased lymph 
flow lasts from forty 
minutes to two 
hours after the in- 
jection. Moreover, 
this rise of pressure 
in the portal vein 
would have more 
influence in in- 
creasing the capil- 
lary pressure in the ) Ba? 10 20 30 40 50 60 70 minutes 
intestines than in = /%- of mussel extract 
the liver. Taking Fic. 43.—To show effects of the injection of a lymphagogue of 


these facts into con- the first class on the blood pressures in the abdominal 
: : organs, and also on the lymph flow. (For explanation of 
sideration, we must curves see Fig. 41.) 


conclude that the 
increased lymph flow observed after injection of lymphagogues of the 
first class cannot be accounted for by a rise of capillary pressure. It 
is open to us to conclude that these bodies act in Heidenhain’s sense 
on the endothelial cells of the capillaries, exciting them to an active 
secretion. It must be remembered, however, that all these bodies are 
active poisons. We should expect them, therefore, to diminish rather 
than to excite the physiological activity of the endothelial cells. We 
have already seen that the effect of a slight injury to or diminished 
nutrition of the capillary wall is to increase its permeability. I would 
explain the action of these bodies, therefore, as dependent on injury to 
the capillary wall, and a consequent enhanced permeability, so that a 
pressure which is very little above the normal capillary pressure is able 
to cause a greatly increased transudation of fluid. 

I have already mentioned that these bodies chiefly affect the capil- 


298 PRODUCTION AND ABSORPTION OF LYMPH. 


laries of the liver. Their action, however, is not absolutely confined to 
that organ. I have experimental evidence that there is a certain 
degree of increased permeability of the intestinal capillaries after the 
injection of these lymphagogues, an increased permeability which is 
brought into evidence only after raising to a certain extent the pressure 
in these capillaries. The first class of lymphagogues also affects the 
capillaries of the skin. In a number of the experiments in which these 
bodies have been injected, we may observe a rapid development of an 
urticarial eruption on the skin, and it-is a matter of common knowledge 
that the ingestion of the animals from which these bodies are derived 
(mussels, crayfish, lobster) is often followed in man by an eruption 
of urticaria which may or may not be accompanied by other symptoms 
of poisoning. 

Another substance which seems to act directly on the capillary wall 
is curari. This body, however, differs from the class of lymphagogues 
under discussion, in the fact that its chief action is on the vessels of the 
limbs. The effect of curari in increasing the lymph production in the 
limbs was noticed long ago by Paschutin working in Ludwig's labora- 
tory. Its direct action on the endothelial wall of the capillaries can be 
easily demonstrated in the living frog’s web. It may be seen that, after 

the injection of curari, the capillary walls become apparently more 
sticky, so that the capillaries become filled with a number of leucocytes 
adhering to their walls. 
s a renewed investigation of the facts discovered 
by Heidenhain has shown that they are not irreconcilable with the 
filtration hypothesis, but rather serve to support it. At the same 
time they prove the extreme importance of the factor upon which 
so much stress was laid by Cohnheim, namely, the nature of the 
filtering membrane. In fact, we may say that the formation of lymph 
and its” composition apart from the changes brought about by diffusion 
and osmosis between it and the tissues it bathes, depend entirely on 
two factors-— 

1. The permeability of the vessel wall. 

2. The intracapillary blood pressure. 

So far as our experimental data go, we have no sufficient evi- 
dence to conclude that the endothelial cells of the capillary walls 
take any active part in the formation of lymph. It seems rather 
that the vital activities of these cells are devoted entirely to maintain- 
ing their integrity as a filtering membrane, differing in permeability 
according to the region of the ‘body in which. they may be situated. 
Any injury, whether from within or without, leads to a failure of 
this their one function, and therefore to an increased permeability, 
with the production of an increased flow of a more concentrated 
lymph. 

We have no evidence that the nervous system has any influence on 
the production of lymph in any part, except an indirect one by altering 
the capillary pressures in the part through the intermediation of vaso- 
constrictor or dilator fibres. This action is better marked in situations 
where the capillaries are normally very permeable or where the per- 
meability has been increased by local injury to the vessels, or by the 
circulation of poisons in the blood stream 


‘Cf. Cohnheim u. Lassar, Virchow’s Archiv, 1878, Bd. Ixxii. S. 132; and Jankow- 
ski, tbid., Bd. xciii. S. 259. 


FORCES CONCERNED IN MOVEMENT OF LYMPH. 299 


THE PHYSICAL FORCES CONCERNED IN THE MOVEMENT OF LYMPH. 


We may now consider briefly the forces which bring about the flow 
of the lymph and chyle from the origin of the lymphatics towards the 
termination of the thoracie duct in the subclavian vein. 

In the living animal the lymphatics, like the blood vessels, are in a 
condition of moderate distension. The lateral pressure in the lymphatic 
duct of the neck was measured in 1849 by Ludwig and Noll! In the 
dog they found that this pressure varied from 8 to 18 mm. sodium car- 
bonate solution. A little later, Weiss? measured the pressure in the 
same vessel in the dog and horse. In the dog he found that it varied 
from 5 to 20 mm.,and in the horse from 10 to 20 mm. soda solution. 
The latter observer ‘also estimated the velocity of the lymph flow in the 
cervical lymphatic by means of Volkmann’s hemodromometer. He 
found that the average velocity was about 4 mm. in the second, a 
velocity which is exceedingly small as compared with the velocity of 
blood in arteries or veins of the same calibre, and is only a few times 
greater than the velocity in the capillaries. Since there is a constant 
flow of lymph from the periphery to the thoracic duct, it is evident that, 
as we trace the lymphatics towards their radicles, the pressure of the 
lymph must increase. This increased pressure in the peripheral parts 
of the lymphatic system is shown by the fact, to which Rudbeck? first 
called attention, that if a lymphatic be emptied by pressure, it always 
fills from the periphery, and if a ligature be placed round it, the vessel 
swells upon the peripheral, and shrinks on the central side of the 
ligature. 

We see then that the first and chief factor in the onward flow 
of lymph is the pressure under which this is formed in the radicles 
of the lymphatics and in the tissue spaces. As the blood flows through 
the capillaries at a given pressure, a certain proportion of its fluid con- 
stituents filters through the vessel wall, forming a transudation which 
is still under a certain amount of pressure, and it is this remaining 
pressure which causes the onward flow of the lymph. Hence the 
ultimate cause of the lymph flow must be looked for in the energy of 
the heart’s contraction. 

When this hypothesis was first put forward by Ludwig and Noll (in 
opposition to the suction theories mentioned previously), it was objected 
to by Donders* on anatomical grounds. At that time it was thought 
that the lymphatics formed a closed system of capillaries, ramifying j in 
the tissues; and Donders pointed out that if the pressure in the tissue 
juices were higher than that of the contents of the lymphatic capillaries, 
the effect would be, not a flow from spaces into capillaries, but a collapse 
of the latter with obliteration of their lumen. Further anatomical 
investigations have shown us, however, that, in the first place, the 
lymphatics are probably not a closed system of tubes, but are in com- 
munication with the tissue spaces (Recklinghausen,? Ludwig); and 
secondly, that the walls of the lymphatics, at any rate in certain situa- 
tions, are so connected by strands of elastic fibres with the surrounding 


1 Loe. cit. 
2 «<Experimentelle Untersuch. ueber die Lymphstrom,” Diss., Dorpat, 1860 (quoted by 
Gruenhagen, Bd. i. S. 282). - 
2 Loc eit. 4 Zischr. f. rat. Med., 1853, N. F., Bd. iv. S. 238. 
_ > Stricker’s ‘‘ Histology,” Syd. Soc. Trans., 1869, vol. i. p. 297. 


300 PRODUCTION AND ABSORPTION OF LYMPH. 


connective tissue, that a rise of tension in the meshes of the latter will 
only drag the walls of the lymphatics further apart, and thus increase 
rather than diminish their lumen.t 

Although the blood pressure is therefore the primary mechanical 
factor in the movement of lymph, there are several other factors which, 
though subsidiary, are of considerable importance. In the first place, the 
flow of lymph through the thoracic duct is much aided by the respira- 
tory movements. In all experiments on the subject of lymph formation, 
it is necessary to maintain the animal in as quiet a condition as possible, 
since any disturbance of the respiratory movements causes a variation 
in the lymph flow from the thoracic duct. With every inspiration, in 
consequence of the descent of the diaphragm, there is a rise of pressure 
in the abdominal cavity, and a fall of pressure in the thorax. Hence 
we get an emptying of the lymphatics of the abdomen, including the 
receptaculum chyli, and a distension of the duet in the thoracic 
cavity. With each expiration the thoracic duct tends to collapse 
to a certain degree and so empties itself into the veins, a backward 
flow of lymph being prevented by the valves in the duct. If a 
manometer be connected by a T-tube with the thoracic duct, it is 
found that there is a rise of pressure during expiration and a fall 
during inspiration, so that during the latter period the pressure may 
become negative. 

Respiration has also an indirect influence on the lymph flow. With 
each inspiration the negative pressure in the thorax is increased, so that 
a negative pressure is also produced in the intrathoracic venous trunks, 
which must cause a suction of lymph through the thoracic duct into the 
subclavian vein. That the blood pressure in the subclavian vem at 
the opening of the thoracic duct is of importance for the flow of lymph, 
is shown by the fact that, if the pressure here is raised in any way, as by 
ligature of the vein, the flow of lymph is entirely stopped, and there 
may be a reflux of blood from the vein into the duct. 

The work of Ludwig and his pupils has revealed to us the existence 
of certain anatomical arrangements for furthering the flow of lymph. 
Thus, in all tendons and aponeuroses of the body, we find a double 
system of lymphatics, consisting of a deep network of capillaries with 
meshes elongated in the direction of the fibrous bundles, and lying 
directly on the muscular fibres ; and a superficial network with polygonal 
meshes lying in the peritendinous connective tissue.2 Both networks 
are in connection by means of small vertical branches, and contain no 
valves. It is found that the slightest pressure or stretching of the 
aponeuroses causes a flow of lymph from the deep into the superficial 
meshwork, and from here into larger lymphatic vessels, which pass 
through the substance of the muscles to join the large lymphatic 
trunks. A very similar arrangement of lymphatics has been described 
by Ludwig and Schweigger-Seidel,? in the central tendon of the 
diaphragm. These may be injected by introducing some coloured fluid 
into the abdominal cavity of a freshly-killed animal, and then carrying 
out artificial respiratory movements. ; 

The physiological proof of these deductions from anatomical obser- 
vations was furnished by Genersich,t who showed that the lymph flow 


Gaskell, Arb. a. d. physiol. Anst. zu Leipzig, 1876. 
“Die Lymphgefiisse der Fascien und Sehnen,” Leipzig, 1872. 
Arb, a. d. physiol, Anst, zu Leipzig, 1866. 4 Tbid., 1870. 


wo np 


= 


Pr 


FORCES CONCERNED IN MOVEMENT OF LYMPH. 301 


could be largely increased by passive flexion and extension of the limbs. 
We must therefore look upon the entire muscular system as one of 
the chief sources of the energy for maintaining the lymphatic circula- 
tion, especially as the presence of valves in the lymphatics converts 
every muscular contraction which may press on the vessels into a 
driving force. 

We have finally to consider the effect of changes in the calibre of 
the lymphatics themselves on the onward flow of lymph. In the frog 
(and in other amphibia, and also in Sawropsida) the lymph circulation 
is maintained by special contractile cavities called ly mph hearts, situated 
in pairs, an anterior pair beneath the scapule, and a posterior pair in 
the ileo-coccygeal space. 


The chief points with regard to the normal anatomy and physiology of the 
batrachian lymph hearts have been summed up as follows, by J. Priestley : ! — 

1. The hearts are muscular sacs, the fibres of which branch and freely 
anastomose and are transversely striated. Their walls are penetrated by 
medullated and non-medullated nerve fibres, and small nerve ganglia are 
situated in the neighbourhood of the hearts, but no ganglion cells 
have as yet been recognised amidst the muscular fibres. They collect the 
lymph from more or less extensive lymphatic regions, and force it past valves 
into large veins, the anterior pair of hearts into branches of the jugular, the 
posterior pair into branches of the ischiatic vein. They are supplied by 
nerves from the spinal cord, the anterior pair by the second, the posterior pair 
by the tenth spinal nerve. 

2. The hearts exhibit throughout life a pulsation with a mean rate of 
sixty to seventy a minute. It is, however, not continuously regular, being 
interrupted by pauses, and by periods of great acceleration. The pauses some- 
times follow movements on the part of the animal, but often they cannot be 
set down to any definite cause. After such pauses the pulsations begin as 
twitches before falling into beats of normal fulness. The periods of acceleration 
also seem to be determined, for the most part, by movements of the animal. 

3. The hearts are governed by cerebro-spinal centres—motor and inhibitory. 
The motor centres are situated in the spinal cord, those for the anterior pair 
opposite the third, and those for the posterior pair opposite the sixth 
vertebra. They transmit their impulses down the appropriate spinal nerves 
of their own side of the body; and each is independent of the rest. They - 
originate the normal rhythm of the hearts ; and their action, whatever its exact 
nature, is automatic, or not due directly to afferent stimuli; hence no change 
in the lymph current traversing the hearts can alter their rhythm. The 
inhibitory centre is situated in the encephalon, in the optic lobes; it is 
constantly in action. 

4, These centres are in connection with afferent nerves. Strong stimuli, 
applied to the blood heart or to the abdominal viscera, lead to inhibition of the 
heart beats, if the upper centre is intact ; while strong sensory stimuli applied 
to the skin may inhibit the lymph hearts whether the upper centre is 
present or not. 

5. But though governed by the above centres, the lymph hearts seem 
capable of an irregular pulsation when separated from them. Such pulsation 
consists of flickers and indefinite confused twitchings for the most part, 
which, when the heart is vigorous, harmonise occasionally to full beats. The 
nature of these movements is still doubtful. The most that can be said about 
them is that they are probably not solely muscular, since curari abolishes them. 


1 Journ. Physiol., Cambridge and London, 1879, vol. i. p. 1. Cf. also the account by v. 
Wittich in Hermann’s “ Handbuch, *” Bd. v. (2) S. 825, where full references to the liter- 
ature of the subject are given. 


302 PRODUCTION AND ABSORPTION OF LYMPH. 


No such mechanism exists in the mammalia. Heller and Colin 
have observed rhythmic contractions of the lacteals in the mesentery, 
but only in the herbivora. In the case of the chyle vessels, Briicke * has 
shown that the onward flow of lymph is helped by the rhythmic con- 
tractions of the muscular fibres of the intestinal villi, which empty the 
central cavity of the villus into the underlying network of lymphaties. 

Since the walls of most lymphatic vessels and of the thoracic duct 
are provided with unstriated muscular fibres, we should. expect these 
vessels to be constricted, in consequence of direct stimulation, and such 
constrictions have been observed in executed criminals. It has been 
shown more recently that an active contraction or dilatation of the 
lymphatics ean be brought about by electrical stimulation of certain 
nerves. Thus Paul Bert and Laffont* noticed contraction of the 
lacteals on stimulation of the mesenteric nerves, and a dilatation of the 
same vessels on exciting the splanchnics. Gley and Camus? have 
lately repeated these experiments more carefully, and have obtained 
graphic evidence of a dilatation of the cisterna lymphatica on stimula- 
tion of the splanchnic nerve. This dilatation of the cisterna probably 
explains the temporary stoppage in the lymph flow from the thoracic 
duet which I described as the immediate effect of splanchnic stimulation. 

It is probable, however, that the active contractility of the walls of 
the lymphatics is of very little importance for the flow of lymph 
through them. The only factors which are of importance are mechanical, 
and are— 

1. The pressure under which the lymph is poured into the tissue 
spaces. This in its turn is dependent on the differences of pressure 
between the intra- and extracapillary fluids, as well as on the per- 
meability of the vessel walls. 

2. All the muscular contractions of the body, and especially those 
by which the respiratory movements are carried out. 


THe ABSORPTION OF LYMPH FROM THE CONNECTIVE TISSUES. 


Relative importance of blood vessels and lymphatics.—Before 
the discovery of the lacteals by Asellius, anatomists ascribed the office 
of absorption generally to the veins. From this time until the begin- 
ning of the present century, no subject was more hotly disputed than 
the question of the relative importance of the veins and of lymphatics 
in the processes of absorption. 

It was generally conceded that the lacteals performed practically 
the whole work of absorbing the products of digestion from the intes- 
tines; but the views as to the functions of the other lymphatics of the 
body were many and various. Thus, when Nuck# first made his 
experiments, in which he thought he injected these lymphatics from the 
arteries, he concluded that they had no other use than as correspondent 
veins, to return the lymph from such arteries as were too small to admit 
the red blood corpuscles. As anatomical and clinical knowledge increased, 
it was gradually recognised that the general lymphatics of the body had 
a function similar to that of the lacteals in the intestines, and hike them 


‘** Ueber die Chylusgefiisse und Fortbewegung des Chylus,” Wien, 1853. 

Compt. rend. Acad. d. sc., Paris, March 13, 1872. 

‘* Recherches dans les causes de la circulation lymphatique,” Diss., Paris, 1824. 
** Adenographia curiosa,” Leide, 1691. 


me OF 1D 


ABSORPTION FROM CONNECTIVE TISSUES. 303 


were able to absorb fluids as well as solids in fine suspension or solution. 
A number of reasons for this conclusion are given by Johannes Miiller, 
and I may quote some of these as an example of the arguments by 
which older anatomists, such as Hunter and Hewson, had come to hold 
this opmion. In the first place, the lymphatics often become painful, 
red streaks appear in their course, and the neighbouring lymphatic 
glands become swollen after the application by friction of nritating 
matters to the skin. Mascagni asserted that, in animals which died 
from pulmonary or abdominal ‘hemorrhage, the lymphatics of the pleura 
and peritoneum were filled with blood (Miller discredits this assertion as 
“extravagant ”’). Mascagni and Soemmering observed bile in the 
lymphatics coming from “the liv er, IN cases W there the bile ducts were 
obstructed. Tiedemann and Gmelin. after tying the ductus choledo- 
chus in dogs, found the lymphatics of the liver filled with a fluid of a deep 
yellow colour. The lymphatic glands through which these lymphatics 
passed were yellow, and the yellow fluid taken from the thoracic duct con- 
tained biliary constituents. The effect of this and similar evidence on the 
minds of the anatomists in Hunter's time was rather curious. Since 
nature had provided a system—the lymphatics—on purpose to serve 
the office of absorption, it was considered in the highest degree 
improbable that this office would also be carried out by the veins, and 
William and John Hunter, as the result of experiments on absorption 
from the intestines, concluded that the veins take no part im absorption. 
To this view of exclusive power of absorption possessed by the 
lymphatics, it was objected that animals exist which possess neither 
lacteals nor lymphatics. It was therefore regarded as a brilliant victory 
for the hypothesis, when Hewson demonstrated the existence of lacteal 
and lymphatic vessels in birds, reptiles, and fishes. 

Subsequent researches, especially by Magendie,? have shown, how- 
ever, that absorption rome all parts of the body can be effected by 
blood vessels as well as by lymphatics. Magendie’s researches have 
been continued and extended of late years hy Ascher? in the case of 
the connective tissues of the lower limbs, by Tubby and myself‘ in the 
ease of the pleural and peritoneal cavities. We found, for example, 
that, after injecting methylene-blue or indigo-carmine into the pleura, 
the dye-stuff appeared in the urme within five minutes, whereas the 
lymph presented no trace of blue for another twenty minutes, or even 
two ‘hours. It is evident that in this case the dye must have been 
taken up by the blood vessels and not by the lymphatics, and that 
this vascular absorption takes place with extreme rapidity. In a later 
series of experiments, Leathes® has shown that, after introduction of 
various salt solutions into the serous cavities, an interchange of con- 
stituents takes place directly between the blood and the injected fiuid, 
so that the latter'in a very short time becomes isotonic with the blood 
plasma. Now, in this mode of absorption by the blood vessels the so- 
called absorption really consists in an interchange between blood and 
extravascular fluids—an interchange apparently dependent entirely 
upon processes of diffusion between these two fiuids. So long as any 


1 Quoted by Miiller (Baly’s translation, vol. i. p. 242). 

2 Précis élémentaire de physiologie, ” Paris, 1836. 

3 Ztschr. f. Biol., Miinchen, 1893, Bd. xxix, 8. 247. 

4 Journ. Physiol., Cambridge and London, 1894, vol. xvi. p. 140. 
5 Thid., 1895, vol. xviii. p. 106. 


304 PRODUCTION AND ABSORPTION OF LYMPH. 


difference in composition exists between intra- and extravascular fluids, 
so long will diffusion currents be set up tending to equalise this 
difference. 

Absorption of isotonic fluids.—These experiments, therefore, have 
no direct bearing on the absorption of lymph, ae. the normal tissue 
juices. In this case the fluid to be absorbed resembles in almost all 
particulars the blood plasma, and possesses the same osmotic pressure 
as the latter, so that it would seem that there are no forces of diffusion 
or osmosis tending to absorption. Miller? concludes from similar 
considerations that “the removal of collections of fluid must be effected 
in many cases by means of the lymphatics, independently of imbibi- 
tion into the capillaries.” The mechanism of this lymphatic absorption 
has been already studied. We have now to inquire whether at any 
time fluids, such as those normally present in the tissues and isotonic 
with the blood, can be taken up by the blood vessels. 

We may arrange the experiments which have been made to decide 
this point under three headings— 

1. In the first set, observations were made on the absorption of 
isotonic salt solutions and blood serum from the pleural and peritoneal 
cavities. Orlow, working under Heidenhain’s direction, found that 
such fluids were absorbed rapidly from the peritoneal cavities of living 
animals, while the lymph flow from a cannula placed in the thoracic 
duct showed no (or only slight) imecrease, in no way comparable to 
the amount of fluid absorbed. He concluded, therefore, that the 
absorption was effected by the blood vessels and was dependent on 
the vital activity of the cells lining the serous cavities or of the 
endothelial cells of the capillaries. Hamburger and Leathes con- 
firmed these results, but showed that they could not depend on any 
vital activity of the endothelial cells, since absorption took place with 
equal rapidity even when poisonous solutions of sodium fluoride were 
employed. 

The great objection to thesé experiments is that they do not prove 
conclusively absorption by the blood vessels. It is still possible that the 
fluids may have been taken up by the subserous lymphatic network and 
had not reached the thoracic duct during the experiment. This is an 
objection raised by Cohnstein,*? who concludes from very similar experi- 
ments that these fluids are carried away solely by the lymphatics. It 
might be thought that this question could be easily decided by observing ~ 
whether fluids were still absorbed from the serous cavities after ligature 
of both lymphatic ducts. I have made a number of experiments of this 
description, but have failed to get decisive results. It is true that, after 
ligature of both thoracic ducts as well as of the right innominate vein, 
isotonic salt solutions were taken up fairly quickly from the serous 
cavities. In none of these cases, however, could I be certain that the 
lymph was absolutely shut off from the blood. As a rule I injected 
on three succeeding days several hundred e.c. saline solution into the 
peritoneal cavity, the last injection containing carmine granules in 
suspension. On killing the dog two days after the last injection, the 
peritoneal cavity was generally found to be empty, and carmine granules 
could be traced along the glands of the anterior mediastinum, showing 
that, in spite of the ligature of both lymphatic ducts, there had been a 


peace: 2 Arch. f. d. ges. Physiol., Bonn, 1894, Bd. lix. S. 170. 
3 Centralbl. f. Physiol., Leipzig u. Wien, 1895, Bd. ix. 


ABSORPTION OF ISOTONIC FLUIDS. 305 


passage of lymph upwards and through the chest. We must therefore 
look to other methods to decide this question. 

2. There is a whole series of experiments made by other observers 
which I think prove conclusively the power of the blood vessels to take 
up fluid from the tissue spaces. If an animal be bled several times, it 
will be found that the blood obtained in the later bleedings is more 
watery than that obtained at the beginning of the experiment. Now 
this diminution of total solids in the blood seems to be due chiefly to a 
dilution of the serum; the serum contains less solids than before, and is 
increased in volume relatively to the blood corpuscles. I may here 
quote some observations which show this point. 


Dog 11°4 kilos.—Solids of serum=7-72 per cent. Dog then bled to 
220 c.c. Thirty minutes later, solids of srum=7:'14 per cent. 

In another experiment the solids of the serum were at first 6°98 per cent. ; 
after bleeding to 200 c.c.=6°57 per cent.; after further bleeding to 100 c.c. 
= 6°37 per cent. 

In a smaller dog (6°5 kilos.), withdrawal of 150 e¢.c. blood reduced the 
solids of the serum from 7°77 per cent. to 6°47 per cent. 


It must be noticed that this attempt to regulate the amount of the 
circulating blood by bringing it up to its normal volume is carried out 
with great rapidity, so that it is, even while an animal is being bled, 
found that the later portions of blood are more dilute than the earlier 
portions. That the fluid which is added to the blood in these cases is 
derived from the tissues or tissue spaces, is shown by Lazarus-Barlow’s 2 
experiments. This dilution of the blood takes place even when the 
thoracic duct is tied or when the lymph is conducted away by placing a 
cannula in the duct, so that it cannot be due, as was formerly thought, 
to an increased lymph flow into the blood. 

3. In order to be absolutely certain of the power of the blood 
vessels to take up isotonic solutions and dropsical fluids from the 
tissue spaces, I carried out a series of experiments,’ in which I led 
defibrinated blood through the blood vessels of amputated limbs. In 
each case I had a double set of transfusion apparatus, and sent one-half 
of the blood many times through a limb which had been rendered 
dropsical by the injection of isotonic salt solution, while simultaneously 
fluid was flowing at the same pressure through the other limb, which was 
not dropsical, and thus served as a control. In each case the blood was 
analysed and its hemoglobin estimated before the experiment, and from 
both limbs after the experiment. It was invariably found that, whereas 
the blood which had passed from twelve to twenty-five times through 
the sound limb had become rather more concentrated, the blood which 
had passed through the oedematous limb had taken up fluid from this 
limb. I may here quote one of these experiments as an example :— 


Total Percentage 
Solids. of Oxyhzemoglobin. 
1. Blood before experiment 21-2 per cent. 100 


2. After twenty passages through 
normal leg ; : ; sy tr) | ae Aaa 103 
3. After twenty passages through 


cedematous leg LoL) | Mie O55 


1 Tscherewkow, Arch. f. d. ges. Physiol., Bonn, 1895, Bd. xii. S. 304. 
2 Journ. Physiol., Cambridge and London, vol. xvi. p. 13. 
3 Tbid., 1895, vol. xix. p. 312. 


VOL. I.——20 


306 PRODUCTION AND ABSORPTION OF LYMPH. 


From a consideration of these facts we must conclude that lymph 
and saline solutions, isotonic with the blood, may be taken up by the 
blood circulating through the capillaries, and that this process may 
occur comparatively rapidly. 

Effect of intracapillary pressure.—We have already seen how 
any excess of intracapillary pressure, such as accompanies plethora, 
causes an increased transudation from the capillaries, so that the 
volume of circulating fluid is diminished. Now we see that, on any 
diminution of capillary pressure taking place, as after bleeding, the 
fluid in the tissue spaces goes back into the vessels to make up for 
the volume of circulating fluid lost. This wonderful balance between 
capillary pressure and lymph production or absorption is, I think, 
well illustrated by Lazarus Barlow’s observations. This author has 
shown that the slight plethora produced by wrapping up a limb in 
Esmarch’s bandage causes an appreciable increase in the transudation in 
other parts of the body, so that the specific gravity of the tissues of the 
upper limb for instance falls, while the specific gravity of the blood 
rises. The reverse is the case when circulation is restored to a limb 
which has been kept anemic for an hour or two. Here considerable 
hyperemia of the affected limb is produced, and corresponding anemia of 
other parts of the body. We find, then, that absorption as well as trans- 
udation through the capillary wall is determined by the intracapillary 
pressure. When the pressure rises transudation is increased, when the 
pressure falls absorption is increased. We have seen that the depend- 
ence of transudation on capillary pressure is susceptible of a fairly simple 
mechanical explanation. We have now to discuss the mechanism of the 
absorption process. 

Mechanism of absorption.—Filtration.—Is absorption effected by 
the active intervention of the endothelial cells, or are there physical 
factors at work which will serve to explain it? An explanation of 
absorption, which will strike anyone who investigates this problem, is 
that it may take place in the same manner as lymph is produced, 
i. by a process analogous to filtration. A series of mechanical 
experiments by Klemensiewicz! would seem at first sight to show 
that such a backward filtration is impossible. Klemensiewicz points 
out that, if fluid be passing at a given pressure through a permeable 
tube contained within a rigid tube, transudation will occur until the 
pressure of the transuded fluid is equal to that of the fluid flowing 
through. At a certain point in the experiment the pressure of the 
transuded fluid will exceed the pressure at the outflow end of the 
tube. The tube will collapse and the flow through it will be stopped. 
He imagines that the same sequence of events occurs in the living 
body in the presence of a considerable transudation. Arteries, capil- 
laries, and veins are bathed in the transuded fluid. The fluid which 
leaves the capillaries will, if a free outflow for it be absent, after 
a time attain a pressure near that ruling in the capillaries and higher 
than the venous pressure. :The veins will therefore collapse, venous 
obstruction will be produced, and the capillary pressure and trans- 
udation will be higher than ever, so that we have a vicious circle 
of events tending continually to increase the cedema of that part. 
Now Klemensiewicz’ objections are true only under one condition—ze. 
that the venous tubes should run freely through the lymphatic spaces of 

1 Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1881, Bd. lxxxiv.; 1886, Bd. xciv. 


MECHANISM OF ABSORPTION. 307 


the tissues. If, however, we consider a system in which the inner 
tube is connected at various points in its circumference to the outer 
tube by strands of fibres, it is apparent that a rise of pressure in the 
space surrounding the inner tube will only serve to extend this tube 
still further. No collapse will take place, but a back filtration will be 
possible. If we cut sections of injected connective tissues, we find 
that the capillaries are bound to surrounding parts by radiating fibres 
which might possibly prevent their collapse under high extravascular 
pressure. In the larger veins, on the other hand, the arrangement of 
the fibres of the adventitia is circular and not radial, so that a high 
extravascular pressure would apparently cause collapse of the veins. 
From these anatomical facts one would conclude that a backward filtra- 
tion is possible, provided that the extravascular pressure be raised in the 
region of the capillaries. If, however, the pressure be freely propagated 
through the tissues so as to affect the larger veins draining them, we 
shall have collapse of the veins and increased cedema. Here, as in so 
many other cases, we cannot get a decisive answer to our physiological 
questions by purely anatomical investigation, but must have recourse to 
physiological experiment. 

The question that we have immediately to decide is, whether an 
increased tissue tension augments or leaves unaltered the flow of blood 
through the tissues, or whether it causes venous collapse and so 
diminishes the flow. In the former case a back filtration would be 
possible, and in the latter case impossible. I have investigated this 
point in various regions of the body, eg. the connective tissues of the 
leg, the tongue as a type of muscular tissue, and the submaxillary gland 
as a type of glandular tissue. In all these cases I have found that a rise 
of tissue tension above the pressure in the veins causes collapse of these 
veins, a rise of capillary pressure, and a diminished flow of blood through 
the part. In these regions of the body, therefore, absorption of lymph 
by a backward filtration is impossible. 

Imbibition.—Hamburger,! finding that serum and isotonic fluids are 
absorbed from the peritoneal cavities of animals that have been dead some 
hours, concludes that the life of the endothelial cell can have nothing to do 
with the process, and ascribes the absorption to processes of capillary and 
molecular imbibition, so that the absorption of fluids would be analogous 
to the taking up of fluids and gases by animal charcoal. Though these 
factors probably co-operate to a certain extent in the distribution of the 
fluid through the tissues surrounding the serous cavities, it is evident 
that they would be much more pronounced in dying and disintegrating 
tissues, and could with difficulty explain the taking up of fluids by the 
blood vessels. They would certainly not explain the wonderful balance 
which exists between the intracapillary pressure and the amount of 
fluid transuded from or absorbed by the blood vessels. What, then, is 
the explanation of this absorption ? 

Osmosis.—The explanation is, I believe, to be found in a property 
on which much stress was laid by the older physiologists, and which 
they termed the high endosmotice equivalent of albumin. It must 
be remembered that the older physiologists used animal membranes 
in their experiments on osmotic interchanges. These membranes permit 
the passage of water and salts, but hinder the passage of coagulable 
proteid. The application of semipermeable membranes to the measure- 


1 Arch. f. Physiol., Leipzig, 1895, S, 281. 


308 PRODUCTION AND ABSORPTION OF LYMPH. 


ment of osmotic pressure has shown that the osmotic pressures of salts 
and other crystalloids are enormously higher than those of colloids 
such as albumin, and it has therefore been supposed that the osmotie 
pressure of the proteids in the serum, being so insignificant, must be of 
no account in physiological processes. The reverse is, however, the 
case. Whereas the enormous pressures of the salts and crystalloids in 
the various fluids of the body are of very little importance for most 
physiological functions, the comparatively insignificant osmotic pressure 
of the albumins is of great importance—and for this reason. It has 
been shown that bodies in solution behave in most respects like gases. 
Now, there can be no difference in pressure between two gases in a vessel 
which are not separated or are only divided by a screen freely permeable 
to both gases. In the same way,if we have two solutions of crystallised 
substances separated by a membrane which offers free passage to the 
water and the salts on either side, there can be no enduring difference of 
the osmotic pressure on the two sides, especially if a free agitation of 
the fluids on both sides is kept up. The pressures on the two sides will 
be speedily equalised, and then any flow of fluid from one side to the 
other will cease. Now, the capillaries in the living body represent such 
a membrane. Leathes! has shown that, within five minutes after the 
injection of sugar or salt into the blood vessels, their osmotic pressures in 
the blood and lymph have become equal. Supposing, however, that we 
have on one side of this membrane a substance to which the membrane 
is impermeable, this substance will exert an osmotic pressure and will 
attract water from the other side of the membrane with a force propor- 
tional to its osmotic pressure. This attraction of fluid must go on until 
all the fluid has passed through the membrane to the side where the 
indiffusible substance is. 

Now the capillaries of the limbs are almost impermeable to proteids. 
In consequence of this impermeability, the fluid which is transuded 
from the capillaries under pressure contains very little proteid. From 
what I have just said, it follows that the proteids left in solution within 
the capillaries must exert a certain osmotic attraction on the salt 
solution outside the capillaries. It is easy to measure the value of this 
attractive force. If we place blood serum in a small thistle funnel, over 
the open end of which is stretched a layer of peritoneal membrane 
soaked in gelatine, and immerse the inverted funnel into salt solution 
which is isotonic or even hypertonic as compared with the serum, 
within the next two days fluid will pass into the funnel and will rise in 
its capillary stem to a considerable height. I have found that the 
osmotic pressure of the non-diffusible portions of blood serum, measured 
in this way, may amount to about 30 mm. Hg. The importance of 
this fact is obvious. Although the osmotic pressure of albumin is so 
insignificant, it possesses an order of magnitude comparable to that of 
the capillary pressures; and whereas capillary pressure determines 
transudation, the osmotic pressure of the proteids of the serum 
determines absorption. Moreover, the osmotic attraction of the serum 
for the extravascular fluid will be proportional to the force expended in 
the production of this extravascular fluid, so that at any given time 
there must be a balance between the hydrostatic pressure of the blood in 
the capillaries and the osmotic attraction of the blood for the surround- 
ing fluids. With increased capillary pressure we shall have increased 


1 Journ. Physiol., Cambridge and London, 1895, vol. xix. p. 1. 


OSMOSIS. 309 


transudation, until we get equilibrium established at a somewhat higher 
point, when there is a more dilute fluid in the tissue spaces, and there- 
fore a higher absorbing force to balance the increased capillary pressure. 
With diminished capillary pressure there will be an osmotic absorption 
of salt solution from the extravascular fluid until this becomes richer in 
proteids, and the difference between its osmotic pressure and that of the 
intravascular plasma is equal to the diminished capillary pressure.t 

Here, then, we have the balance of forces necessary to explain the 
accurate regulation of the quantity of circulating blood according to the 
conditions under which the animal may be placed, and it seems 
unnecessary to invoke the aid of vital activity to explain the process. 
Certain corollaries of this mode of explanation agree well with observed 
facts of experiment. Thus the more impermeable the capillary the 
smaller will be the amount of proteid exuded with the lymph. A 
higher capillary pressure will therefore be needed in its production, and 
there will be an equally high force tending to its reabsorption. A rise of 
capillary pressure will only increase the amount of lymph in the 
extravascular spaces to a certain extent, but will at the same time cause 
this lymph to be more dilute, so that there will be a corresponding rise 
in the force tending towards absorption. In consequence of this 
sequence of events, considerable alterations of capillary pressure may 
be produced in impermeable capillaries, such as those in the limbs, 
without causing any appreciable increase in the lymph overflow from the 
limbs. On the other hand, where the capillaries are very permeable, 
very little pressure will be required to cause a transudation, since no 
work is done in the concentration of a proteid solution, and we find as a 
matter of fact, that capillaries where the pressure is lowest—z.e. in 
the liver—are also those which are the most permeable. Here, too, 
the absorbing force will be insignificant, since there is very little 
difference in the percentage of albumin between liver blood and liver 
lymph. 

Moreover, since the pressure on the venous side of the capillaries is 
considerably less than that on the arterial side, there will be a continual 
exudation of a very dilute lymph from the arterial capillaries, and a 
re-absorption of water and salts from this lymph in the venous 
capillaries. The lymph, therefore, will assume a composition such that 
the osmotic pressure of its proteids approximates the mean capillary 
pressure in the part where it is formed. 

This osmotic difference between blood plasma and tissue fluid will 
not serve to explain the absorption of proteids by the blood vessels nor the 
absorption of serum from the serous cavities. It is difficult, however, if 
not impossible, to prove that serum or proteid is absorbed by the blood 
vessels. In some of my transfusion experiments I have rendered a limb 
cedematous by means of serum, and in these cases have obtained no 
evidence at all of absorption by the blood vessels. There is no doubt 
that serum may be absorbed from the pleural and peritoneal cavities, 
but the absorption of these fluids is very much slower than the absorp- 
tion of salt solutions, and is, in fact, so slow that the whole of it can in 
most cases be effected by the lymphatic channels. A slow absorption of 
serum from tissue spaces by means of the blood vessels is also physically 
possible. As the cells of the tissues feed on the proteids of the fluid, 


1¥For a fuller discussion of this point, cf. Science Progress, London, 1896, vol. v. 
pa. Lol. 


310 PRODUCTION AND ABSORPTION OF LYMPH. 


the serum will tend to become gradually weaker, so that the watery 
and saline constituents corresponding to the proteid used up can then 
be absorbed by the blood vessels in the way I have indicated. 

The physical process which I have described above as causing the 
absorption of lymph by the blood vessels must be in action at all times 
in the body, and must therefore be a predominant factor in the process of 
absorption. I have not been able to absolutely exclude the absorption 
of proteids by the blood vessels, but, in the absence of direct experi- 
mental evidence that such an absorption does occur, the physical factors 
I have described in this chapter suffice to explain the phenomena of 
absorption observed both under normal and under pathological conditions. 


On THE FUNCTIONS OF THE LYMPH IN THE NUTRITION OF 
THE TISSUES. 


The fact that the tissue cells are bathed by lymph and are 
separated by this fluid and by the capillary wall from the blood, 
shows that in all interchanges between blood and tissues the lymph 
must act as the medium of communication. 

I have already mentioned the irrigation theory of Bartholin, accord- 
ing to which the nutrition of the tissues was carried out by a taking up 
of solids from the lymph as it left the blood vessels, so that only pure 
water (or water and salts—Rudbeck) was left over to be carried away 
by the lymphatics. 

The observations of the Ludwig school on the lymph flow from the 
limbs, showed clearly, however, that the nutrition of the tissues could 
be normally carried out without any lymph flow at all. The muscles 
of a resting limb are taking up nourishment as well as oxygen from the 
blood, and giving off their waste products, carbonic acid and ammonia, 
although not a drop of lymph may flow from a cannula placed in a 
lymphatic trunk of the limb. It is evident, therefore, that to a large 
extent, at any rate, the giving up of nourishment by blood to tissues and 
the taking up of the waste products of the latter through the inter- 
mediation of the lymph, is carried out in the same way as are the gaseous 
interchanges—i.e. by a process of diffusion. 

I have already mentioned the experiments which demonstrate the 
extreme rapidity with which diffusion takes place between the blood and 
the lymph, so that, as Leathes points out, the time taken for the 
equalisation of the constitution of the two fluids after introduction of 
some diffusible substance into the blood is “inappreciable.” There can 
be no doubt that such changes are of great importance for the normal 
metabolism of the tissues. Thus there has been considerable discussion 
of late years concerning the supply of lime to the cells of the mammary 
gland. Heidenhain pointed out that if the lime were supplied to the cells 
by filtration, the whole flow from the thoracic duct would be inadequate 
for the purpose. His conclusion that the lymph with its constituents is 
therefore a secretion is, however, unnecessary. As the gland cell uses 
up or turns out lime into the ducts of the gland, it will take up lime 
from the adjoining lymph, thus lowering the partial osmotic tension of 
the lime in its neighbourhood. There will be, therefore, a passage of 
lime from blood to lymph by a process of diffusion, to supply the 
deficiency. No flow of lymph at all is necessary to furnish the amount 
of lime required by the gland cell. 


FUNCTIONS OF THE EYMPH. 311 


The case is rather different when we come to consider the supply of 
proteid food to the tissues. The diffusibility of the large molecular 
serum proteids is so small that it may be disregarded, even in the 
living body with its wonderfully perfect arrangement for allowing the 
free contact of fluids without intermingling. Hence the only way by 
which the tissues can obtain their supply of proteid is from the proteid 
which has filtered through the vessel wall in the lymph. So far as the 
proteid supply to the tissues is concerned, therefore, I believe that the 
irrigation theory is correct, unless, indeed, we attribute to the vascular 
epithelium the power of actively taking up proteid and transferring it 
from one side of the vessel wall to the other in proportion to the needs 
of the tissues. 

Even under the former hypothesis, however, we could not, from the 
amount of lymph draining away from a part, draw any conclusions as to 
the amount of proteid which has been supplied to the part. As I 
have above shown, the composition of the lymph is determined by the 
permeability of the wall and the mean capillary pressure. If the com- 
position of the lymph be altered after transudation, in consequence of 
an active using up of the proteids of the tissue cells, the effective 
osmotic difference between blood and lymph will be increased, and the 
watery and saline constituents of the lymph will be reabsorbed until the 
original constitution of the lymph is restored. 

We may conclude, therefore, in default of definite evidence to the 
contrary, that while the interchange between tissues and blood, so far as 
diffusible substances are concerned, is effected by diffusion through the 
medium of the lymph, the proteid supply to the cells is dependent on 
the amount of proteid transuding with the lymph. 

Perhaps it is on this account—ie., increased proteid supply to the 
cells—that chronic inflammation or hyperemia of any part is apt to lead 
to its hypertrophy. Growing tissues, as well as those in a state of repair, 
have delicate vessels, which probably supply a lymph much richer in 
proteids than is supplied to adult tissues. 


CHEMISTRY OF THE DIGESTIVE PROCESSES. 
By B. Moors. 


ContTENts :—Digestive Ferments, p. 312—Chemical Composition of Digestive Juices, 
p- 342—Saliva, p. 342—Gastric Juice, p. 349—Pancreatic Juice, p. 366—Intes- 
tinal Juice, p. 368— Bile, p. 369—Digestion of Carbohydrates, p. 392—Digestion 
of Proteids, p. 428—Absorption of Carbohydrates and Proteids, p. 430— 
Digestion and Absorption of Fats, p. 443—Bacterial Digestion, p. 463—Com- 
position of Feces, p. 472. 


THE DIGESTIVE FERMENTS, OR ENZYMES. 


Organised and unorganised ferments.—Fermentation is invariably 
brought about, directly or indirectly, by cell life, either vegetable or 
animal. When the action is direct, and the chemical changes involved 
in the process occur only in the presence of the cell, the latter is 
spoken of as an organised ferment. When the action is indirect, and 
the changes are the result of the presence of a soluble material secreted 
by the cell acting apart from the cell, this soluble substance is termed 
an unorganised ferment, soluble ferment, or enzyme." 

The action of an organised ferment is intimately connected with the 
life of the cell, and is instantly stopped by anything which either kills 
the cell or temporarily arrests its activity; while that of a soluble 
ferment is not a vital process, but one which is purely physical or 
chemical in its nature. As a consequence, an organised ferment 1s 
destroyed, and its specific action stopped, by any protoplasmic poison,” 
while an unorganised ferment, provided it is not precipitated, is un- 
affected by such reagents. 

All the differences in the mode of action of organised and un- 
organised ferments arise from this close connection of the organised 
ferment with the cell. Thus, an organised ferment, provided there is a 
supply of nitrogenous food at its disposal, can grow and multiply ina 
medium in which it is sown, while an unorganised ferment can never so 
increase in quantity ; from this it follows that the rapidity of action of 
an unorganised ferment depends (within limits) on the initial quantity 
added, but in the case of an organised ferment the initial amount soon 
becomes a matter of no moment. 

Organised ferments are unicellular organisms (microfungi), while the 


1This term was first used by Kiihne, Verhandi. d. naturh.-med. Ver. zu Heidelberg, 
1879, N. F., Bd. i. S. 236. 


* Such as any of those substances commonly known as antiseptics. 


ATTEMPTS TO ISOLATE PURE ENZYMES. 3103 


unorganised ferments are typically found in the secretions of specialised 
cells of the higher plants and animals, and take an important part im 
the chemical changes involved in their nutrition. 


There is probably at bottom very little difference in the manner of action 
of cellular ferments and enzymes. From the cefl substances of several 
bacteria, extracts have been obtained possessing the same fermentative action 
as the living bacteria; this indicates that in such bacteria, substances are 
present in the cell which act like ordinary unorganised ferments, but normally 
remain during the life of the cell within its substance, and perform their 
fermentative functions there. 

A good example of such an isolation of an unorganised from an organised 
ferment, is afforded by that series of brilliant researches into the nature of 
the action of the micro-organism, forula urex, upon urine, which began with 
the observation that the change into ammonium carbonate was not stopped by 
the presence of carbolic acid in sufficient amount to paralyse the growth of 
the micro-organism,! and ended in the extraction from the bacteria of 
a soluble ferment, which converted urea into ammonia and carbonic acid, even 
in the presence of chloroform, which effectually stops all bacterial action.” 

In a similar manner, a soluble ferment, capable of inverting cane sugar, 
can be extracted from yeast cells after they have been killed by the action of 
alcohol or ether,* and from certain putrefactive bacteria unorganised ferments 
have been obtained, possessing an action on proteids analogous to that of the 
proteolytic ferment of the pancreatic juice. Such intracellular soluble ferments 
have not been shown to exist in by far the greater number of organised ferments, 
but if they do so exist the only remaining difference between organised and 
unorganised ferments is that in the former the substance formed by the cell 
remains in the cell substance, and does its work there, the products of its 
action being poured forth as a kind of secretion or excretion, while in the 
latter the ferment becomes separated from the cell in a secretion, and carries 
out its work apart from the cell. 


Most of the chemical changes involved in the digestion of the food 
are brought about by the presence in the digestive secretions of soluble 
ferments. So that digestion might be described as the physical and chemical 
alteration of the foodstuffs, into forms better fitted for absorption, by the 
action of certain soluble ferments, the digestive enzymes. 

Attempts to isolate pure enzymes.—Many attempts have been 
made to isolate chemically pure enzymes, but the task is very difficult, 
and it is highly probable that no one has yet succeeded in obtaining a 
pure product. 

There are two great difficulties in the way: first, our ignorance of a 
specific precipitant for any of the enzymes; and, secondly, the extremely 
small quantities in which they are present in the secretions. On account 
of the first, the enzyme cannot be thrown out of solution unaccompanied 
by other substances; on account of the second, it is not present in 
workable quantity, and is rapidly lost in any lengthened process of 
chemical manipulation. When to these disadvantages are added the 
non-diffusibility of the enzymes, which shuts out a means of separating 
them from the traces of proteid which always accompany them, and 
their sensitiveness to reaction and temperature, some idea is obtained of 
the difficulties which the problem of isolation presents. © 


1 Hoppe-Seyler, Med.-chem. Untersuch., Berlin, 1871, Heft 4, 8. 570. 
2 Sheridan Lea, Journ. Physiol., Cambridge and London, 1885, vol. vi. p. 136. 
3 Hoppe-Seyler, Ber. d. deutsch. chem. Gesellsch., Berlin, 1871, S. 810. 


314 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


Method of mechanical precipitation.—W hen an indifferent precipitate 
is produced in a solution containing an enzyme, this is often carried 
out of solution with the precipitate, probably in a condition of mechanical 
adhesion. This observation was made by Briicke, who utilised the 
property to free pepsin as far as possible from other substances. The 
method has been extended to the preparation of purified forms of other 
enzymes, and, as applied by Briicke+ to pepsin, may be quoted as an 
example of a general method. It is as follows :— 


The mucous membrane of a pig’s stomach is submitted to partial self- 
digestion, in water acidulated with phosphoric acid; the products of this 
first digestion are rejected, being too rich in products of digestion, and not 
containing much pepsin, which clings in great part to the mucous membrane. 
The residue of the mucous membrane is again digested in water made acid 
with phosphoric acid, and after some days is filtered from insoluble residue, 
and just neutralised by the addition of lime water. The insoluble calcium 
phosphate so precipitated carries down with it all the pepsin ; it is collected on 
a filter paper, just dissolved by cautious addition of very dilute hydrochloric 
acid, filtered off, and once more precipitated by the addition of just sufficient 
lime water. This double precipitation is to free the pepsin of proteid, which 
also has the property of being mechanically carried down, though more feebly 
than pepsin. ‘To this somewhat purified solution of pepsin a solution of 
cholesterin in four parts of alcohol and one part of ether is added. On this 
solution mixing with the water the cholesterin becomes insoluble, and is thrown 
out of solution in a finely divided condition, carrying the pepsin mechanically 
adhering to it just as it did to the calcium phosphate. The mixture is well 
shaken up, and then filtered ; the precipitate is washed first with water, then 
with water acidulated with acetic acid, and finally with water alone. It is 
next, without drying, shaken up with ether, free of alcohol, but saturated 
with water. The ether extracts the cholesterin, while the pepsin remains in 
the watery layer beneath ; the extraction is repeated with fresh portions of 
ether until all the cholesterin has been removed, and finally the watery 
solution containing the pepsin is filtered. In this manner a solution is 
obtained, which actively peptonises, but contains so little proteid as not to give 
many of the proteid reactions. 


Method of auto-digestion—Kiihne and Chittenden? have combined 
auto-digestion with precipitation by ammonium sulphate as a means of 
preparing purified solutions of pepsin and trypsin. The following is an 
outline of their methods :— 


For the preparation of pepsin the mucous membrane of a pig’s stomach is 
taken, and allowed to undergo auto-digestion for several days, until peptonisa- 
tion has far advanced, and but comparatively little albumose is left. The 
solution, after filtration from undigested débris of nuclein, etc., is next satu- 
rated with ammonium sulphate. The pepsin is thus completely thrown out 
of solution along with the albumoses ; this precipitate is dissolved again, after 
pressing in filter paper, in dilute hydrochloric acid, and allowed to go on 
finishing the digestion of the albumoses for some days. 

The process is repeated as often as is necessary to remove the albumose, 
and finally the pepsin, after being dissolved by addition of water, is freed from 


1 Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1862, Bd. xliii. S. 601; ‘‘ Vorlesungen ii. 
Physiologie,” Wien, 1885, S. 308. See also v. Heltzl, Jahresb. ii. d. Fortschr. d. ges. Med., 
Erlangen, 1864, Bd. i. S. 138. 

* Zischr. f. Biol., Miinchen, 1886, Bd. xxii. S. 428. Such a method of auto-digestion 
can obviously only be employed in the case of proteolytic enzymes. 


PREPARATION OF DIGESTIVE EXTRACTS. 315 


ammonium sulphate by dialysis, and may be precipitated by alcohol, filtered 
off and dried as quickly as possible. 


The preparation of a purified trypsin solution is carried out by 
Kiihne’s + method much on the same lines :— 


The pancreas first has all its fat removed by extraction with alcohol 
followed by ether, after which process it forms Kiihne’s “pancreas powder.” 
This is digested with five times its volume of 071 per cent. salicylic acid for 
about four hours. The residue is next digested with 0:25 per cent. sodium 
carbonate solution for a further period of twelve hours, and the solution is 
separated from the undissolved part. The two extracts are now mixed, the 
mixture made up with carbonate of sodium solution to a strength of 0°25 toa 
0°5 per cent. carbonate, and allowed to digest at 40° C. for a week, thymol being 
added to prevent putrefaction (0°5 per cent.). During this time the albumoses 
become converted into peptones, and on saturating “the cold solution, made 
very faintly acid with acetic acid, with ammonium sulphate, trypsin is 

recipitated, accompanied by traces only of unconverted albumoses. The pre- 
cipitate so obtained is sufficiently pure for all digestion experiments. It 
contains so little accompanying albumose, that, from 10 grms. of pancreas 
powder, merely a thin yellowish slime is obtained on the filter paper, yet this, 
when taken up by 100 c.c. of 0°25 per cent. sodium carbonate solution, forms 
a strong digestive fluid. This gives an idea of the extreme power of the 
digestive ferments, and shows at the same time in what mere traces they 
must be present in the glands. This product may be still further purified by 
partially precipitating the solution obtained from it with excess of alcohol, 
dissolving in water, separating by dialysis the bulk of the ammonium sulphate 
also precipitated by the alcohol, removing the last traces of ammonium sulphate 
by barium carbonate, and finally precipitating as a snow-white amorphous 
substance by excess of alcohol. 


This pure product gives all the proteid reactions (unlike Briicke’s 
pepsin), but in spite of all the elaborate and painstaking processes used 
in its preparation, there is no evidence that it does not still contain 
traces of proteid along with trypsin; the other conclusion of course 
would be that trypsin is itself a proteid. 

Preparation of digestive extracts.—When the object is simply to 
test or demonstrate the action of the enzymes, and the admixture of 
products of digestion formed from the gland tissue is a matter of no 
moment, much simpler methods of preparation may be employed than 
those above described. 


1. In many such cases a simple extraction of the gland with water may 
be used, if the action is to be tested immediately. 

2. A general method of obtaining digestive extracts is that first recom- 
mended by v. Wittich,? which consists in preparing a glycerin extract. Such 
an extract has the advantage of efficiency and stability. It contains a good 
deal of proteid, and cannot be used where the products of digestion are to be 
exactly studied, but for general laboratory work glycerin extracts are most 
convenient preparations. They are easily made, and may be preserved for 
years. As the glycerin only slowly extracts the enzymes, the same tissue will 
continue for a long time to yield fresh extracts, if fresh glycerin be added. 

A glycerin extract should not be made with a quite fresh gland, but with 


1 Untersuch. a. d. physiol. Inst. d. Univ. Heidelberg, 1878, Bd. i. S. 222 ; Verhandl. d. 
naturh.-med. Ver. zu Heidelberg, 1886, N. F., Bd. iii. S. 463. See also ibid., 1876, N. F., 
Batwa: 195. 

2 Arch. f. d. ges. Physiol., Bonn, 1869, Bd. ii. S. 193; 1870, Bd. iii. S. 339. 


316 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


a gland which has been minced up and allowed to stand for a few hours (it 
may be in nearly all cases made faintly acid with very dilute acetic acid to set 
free the zymogen as enzyme). Such a minced-up gland is rubbed up in a 
mortar with some clean sand, taken up with glycerin, shaken up with more 
glycerin (10-20 parts to 1 part of gland), and allowed to stand so until 
required ; the process of extraction is very slow, and requires from seven to 
fourteen days. In the case of gastric mucous membrane, | part per 1000 of 
hydrochloric acid may be added to the glycerin. 

There are many modifications of the process. v. Wittich recommends 
digesting the minced gland (or mucous membrane) twenty-four hours in alcohol, 
drying after this in the air, sifting the powder through gauze to remove 
coarser fragments of tissue, and extracting with glycerin. It is often recom- 
mended to filter the extract after seven to fourteen days, but this is unnecessary, 
as the tissue neither decomposes nor becomes digested in the glycerin, and 
the extract improves on keeping in contact with the tissue. The enzyme 
accompanied by proteid may be precipitated from a glycerin extract by the 
addition of absolute alcohol, and so a purer extract be obtained. 


Chemical nature of enzymes.—The failure of all attempts to isolate 
pure enzymes necessarily deprives us of the possession of any certain 
knowledge of the chemical nature of these substances. Analyses of the 
purer preparations of the enzymes give figures approximating to those 
obtained with the various proteids; but whether or not this is due to 
admixture with proteid it is at present impossible to say. The behaviour 
of Briicke’s “ pure” pepsin solution goes against the supposition that this 
enzyme isa proteid. This solution did not give the proteid reactions, 
and was not precipitated by any of the proteid precipitants, save neutral 
and basic lead acetates and platinic chloride. These results are confirmed 
by Sundberg? who succeeded in preparing a still more proteid-free solu- 
tion, which did not even react to these reagents, and was only precipi- 
tated as a slight, pure white, flocculent precipitate, on adding five to six 
times its volume of absolute alcohol and allowing to stand, and yet was 
exceedingly active in digesting fibrin. The amount of this precipitate 
was much too small for analysis, and it could only be shown that it was 
nitrogenous, and contained a certain amount of ash. This is not quite 
conclusive against the proteid nature of the active substance, since, as 
Sundberg argues, the physiological test by digestion may be much more 
delicate than any of the purely chemical tests. Still, the fact that it 
was totally unaffected by tannic acid and precipitated by alcohol has 
some weight against the substance being proteid in nature; since tannic 
acid will show 1 part of ordinary proteid in 100,000,? and alcohol is by 
no means so delicate a proteid test. It is most probable, then, that 
pepsin is not a proteid; and it will subsequently be seen in the descrip- 
tion of the other enzymes that most of these have been obtained in 
forms which do not yield all the proteid reactions. 

The enzymes are soluble in water, from which they are precipitable 
by saturation with ammonium sulphate or by adding excess of alcohol.* 
Most of them are unalterable, or very slowly alterable in contact with 
alcohol, but pepsin is an exception, being attacked and rendered inactive 
if left long in contact. The enzymes are commonly said to be soluble 


1 Ztschr. f. physiol. Chem., Strassburg, 1885, Bd. ix. S. 319. See also under ‘‘ Ptyalin.” 

* Hofmeister, Zischr. f. physiol. Chem., Strassburg, 1878-9, Bd. ii. 8. 292. 

’ These may only be particular cases of their general mechanical precipitation, whenever 
a precipitate is caused. 


MODE OF ACTION OF ENZYMES. a0 


in glycerin, but it has not been shown that the dried enzymes are 
soluble in anhydrous glycerin; on the contrary, Kiihne! states that 
pure trypsin is not soluble in strong glycerin; and it is well known 
that, after precipitation by alcohol from glycerin extracts, the enzymes 
are afterwards much less. soluble in glycerin.” 

An elevated temperature rapidly destroys all enzymes when in 
solution, and it is of some importance that the temperature at which 
they are rapidly destroyed, although it varies considerably with the 
reaction of the solution, lies just a little below the range at which the 
bulk of the proteids coagulate. In the dried condition the enzymes are 
much more resistant to increased temperature, and can be heated to over 
100° C. for some time without losing their digestive properties on cooling 
and dissolving in water. 

The digestive action of the enzymes is not stopped by the presence 
of disinfectants, such as thymol, chloroform, or salicylic acid, in quantity 
sufficient to stop completely the action of organised ferments, particu- 
larly that of the putrefactive bacteria.* This fact has been turned to 
account practically in conducting prolonged digestion experiments, 
especially when the digestive action must be allowed to proceed in 
alkaline solution. 

Mode of action of enzymes.—The manner in which ferments bring 
about the changes characteristic of them is very puzzling. The enzymes 
are altogether unaffected by the changes which they occasion, and, pro- 
vided the products of the action are not allowed to become concen- 
trated in solution, the ferment can work on indefinitely, and a finite 
amount of ferment can convert an imjfinite amount of material. The 
ferment may become by dilution, or unavoidable loss in manipulation, 
so weak that finally its action becomes inappreciable; but before this 
happens it can be shown that it has converted a mass of material so 
many times greater than its own, that the idea that it undergoes any 
permanent alteration in the reaction which it induces must be abandoned. 
Thus, according to Hammarsten,* one part of rennin will curdle 400,000 
to 800,000 parts of milk; while Petit® prepared a pepsin powder which 
in seven hours dissolved 500,000 times its weight of fibrin. 

There are numberless examples of chemical reactions, in which only 
well-known and much simpler compounds take a part, of a substance 
inducing a chemical reaction without itself becoming altered thereby. 
Such a substance is called a catalytic agent, and the reaction a catalysis 
or catalytic reaction. Ferment actions are such catalytic reactions, but 
when we say that ferments act catalytically the problem of how they 
act is not by any means solved; we have merely found a name for it. 

In some eases, in which the presence of a substance is essential to a 
certain reaction, although this substance is not finally altered thereby, 
there is evidence that it is altered intermediately and rechanged again 
back to its initial condition during the reaction. 

Such a case is to be found in the action of sulphuric acid in the con- 
tinuous etherification process for producing ether from alcohol. It can 
be shown that the sulphuric acid first combines with part of the alcohol 


1 Verhandl. d. naturh.-med. Ver. zw Heidelberg, 1876, N. F., Bd. i. S. 196. 

2y. Wittich, Arch. f. d. ges. Physiol., Boun, 1869, Bd. ii. S. 193. 

3 Kiihne, Verhandi. d. naturh.-med. Ver. zw Heidelberg, 1876, N. ¥., Bd. i. S. 190. 
4 Jahresb. ti. d. Fortschr. d. Thier-Chem., Wiesbaden, 1877, Bd. vii. S. 166. 

5 Journ. de thérap., Paris, 1880. 


318 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


molecule, forming a substance which can be isolated, and is known as 
ethylsulphovinic acid; and that this compound then reacts with another 
molecule of alcohol, forming ether and regenerating the sulphuric acid 
molecule, which is then free to repeat the process, and can be made to 
do so indefinitely. 

This action may be represented thus :— 


(1) 0,H,0.H + Ht so, = H.0.H + Sls go, 
(aleohol, sulphuric acid) (water, ethylsulphovinic 
acid) 
re C,H: ¥ NX H Guide , 
(ethylsulpho- (alcohol) (sulphuric (ether) 
vinic acid) acid) 


Another good example of such an interaction is that of the alternate 
formation of a higher oxide of nitrogen (N.O,) from a lower (NO), and 
then the regeneration of the lower oxide, which is said to occur in the 
formation of English sulphuric acid; the oxygen taken up in each 
cycle going to form, with sulphur dioxide and water, sulphuric acid; 
while, as a net result, the nitric oxide remains unchanged, and may take 
action again and again until it is dissipated by diffusion or otherwise.t 

Such a part the enzyme may take in a ferment action; a molecule 
of it may unite with a molecule of the substance undergoing digestion. 
Thus an unstable compound may be formed; the elements of a water 
molecule may combine with those of the fermentable substance, forming 
a new substance; while the ferment is regenerated to undergo another 
cycle. Of all this, however, there is no experimental evidence; there 
is only the analogy, and analogies are sometimes misleading. 

Besides these reactions, there are others in which the action of the 
catalytic agent is, almost undoubtedly, merely a physical one; that is to 
say, in which the catalytic agent does not combine with the catalysed 
substance, and then become regenerated. Such an action, for example, 
is that of a trace of iodine in converting amorphous into red 
phosphorus. Here the amount of iodine required is too excessively 
small to suppose that it combines with phosphorus in one form and 
yields it up in the other. The supposition is more probable that the 
iodine finds the phosphorus in an unstable state, and in some fashion 
enables it to do that which it already hasa tendency to do, namely, swing 
into stability. Such a reaction, only still more physical in character, 
is found in the case of exceedingly unstable compounds (such as 
detonating substances), where mere mechanical percussion, most probably 
by producing molecular vibration, causes a chemical reaction to take 
place with great rapidity. It is very likely that in many cases, 
especially those in which the catalytic agent is merely required to 
be present in traces, that there is no intermediate substance formed, 
and that the catalytic agent acts in a physical manner, inducing a 
compound already unstable to pass into a more stable condition. It 
is not even necessary that the substance should be unstable in the 
usual sense of the word, but only that the new products should be 


1A similar oxygen-carrier, of oxygen to be used in tissue metabolism, is found in 
hemoglobin, which may be looked upon as a catalytic agent, taking up oxygen, parting 
with it to bring about a reaction, the details of which we do not know, and so becoming 
regenerated and coming out of the total process unchanged. 


NATURE OF THE CHEMICAL CHANGE. 319 


more stable; or, in other words, that there should be energy set free in 
the process of change. 

In ferment action, the chemical energy of the resulting products 
is always less than that of the substances from which they were formed ; 
this is shown by the heats of combustion of the end products amounting 
to less than those of the initial products. 

The action of ferments is hence in all respects analogous to that of 
catalytic agents; there is a passage from a less stable to a more stable 
condition, which is brought about by an agent which is not itself altered 
in the process. 

The two principal hypotheses are then—(1) That the enzyme 
combines with the substance on which it is acting, and that the unstable 
compound so formed decomposes, yielding the new substance and 
regenerating the enzyme; (2) that the enzyme is in a state of molecular 
movement, which induces a molecular movement in the fermentable 
substance, or increases such a movement when already present, so that 
the molecule breaks up, over-swings, or over-vibrates as it were, into a 
more stable condition, so giving rise to new substances. 

Nature of the chemical change.—Somewhat more is known of the 
nature of the chemical changes induced by the ferments than of the 
mode in which they bring about such changes. It is probable that in 
all cases ferment action is accompanied by hydrolysis, i.e. the taking 
up of the elements of water.t This is known with certainty to be the 
case in all actions of diastatic and inverting ferments, and is very pro- 
bably true also for proteolytic ferments. This subject will be considered 
more in detail in treating of the specific action of the various enzymes 
on the different classes of foodstuffs; reference will only be made here 
to the general arguments which go to show that such a process of 
hydrolysis is a universal accompaniment of ferment action. 

1. In many cases the composition of the products of the fermentation 
compared with that of the initial substance shows directly a taking up 
of water. In those in which this is not so, carbonic anhydride is usually 
one of the constituents, and if this be considered as united with the 
elements of a water molecule to form carbonic acid, as it probably is 
when formed in the reaction, water is taken up here also. In all cases, 
however, whether the products of the reaction directly show the taking 
up of water or not, the presence of water is essential to the reaction, 
for no ferment is known which will act otherwise than in the presence 
of water. 

2, Again, the action of any of the ferments may be closely imitated 
by the action on the several fermentable or digestible materials of 
dilute acids or alkalies, and these are recognised throughout the domain 
of organic chemistry as the most powerful hydrolytic agents known. 

3. It has been shown that in the case of coagulation by fibrin ferment 
an increase of weight of dried material takes place, probably due to the 
elements of water being taken up in the process. This was demonstrated 
by taking two equal portions of plasma, allowing one to clot and not the 
other, and then drying both under similar conditions, when the clotted 
sample was found to weigh a half per cent. more than the other.” 


1 Hoppe-Seyler, Arch. f. d. ges. Physiol., Bonn, 1876, Bd. xii. S. 1; Nencki, Journ. 
f. prakt. Chem., Leipzig, 1879, Bd. xvii. S. 105. 

? Observation by A. Schmidt, communicated by G. Tamman, Zschr. f. physiol. Chem., 
Strassburg, 1892, Bd. xvi. S. 271. 


320 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


Rate of zymolysis! or enzymic action.—The rate at which diges- 
tion goes on in any digestive fluid varies chiefly with the following 
conditions, namely—(1) The temperature, (2) the reaction, (3) the con- 
centration of the products of digestion, (4) the concentration of the 
digestive enzyme, (5) the condition of the material to be digested. 

Temperature—The digestive enzymes are very sensitive to changes 
in temperature; they all act most energetically at or slightly above the 
body temperature. The point of greatest activity is called the optimum 
point ; as the temperature varies, either above or below this point, the 
rapidity of action of the enzyme slackens ; and, as the interval apart from 
the optimum point is increased, a point is finally reached at which the 
action of the enzyme is no longer appreciable. Any temperature 
markedly above that of optimum action slowly destroys the enzyme, 
and this destructive action in all cases becomes very rapid at tempera- 
tures varying (between 50° and 65° C.) with the particular ferment, the 
reaction of the fluidin which it is so heated, and the degree of its dilu- 
tion2 On the other hand, low temperatures, though they slow and 
finally stop ferment action, do not destroy the ferment; this recovers its 
activity completely when the temperature is again raised, even though 
the temperature has been kept at — 5° C. for several hours.* 

Reaction —The variation in chemical reaction of the fluid in which 
they act has a similar effect on enzymes to that of variation in tempera- 
ture. For each of the digestive enzymes there is a particular reaction, 
and degree of that reaction, at which it acts with maximum power. A 
departure from this degree of acidity or alkalinity causes a more or less 
rapid diminution in the speed with which the enzyme acts, and a 
sufficient amount of departure from the optimum reaction causes the 
destruction of the enzyme. Some of the enzymes act in solutions of 
either acid, neutral, or alkaline reaction, provided always that the 
reaction does not stray too widely from that at which they act best; 
examples of such are ptyalin and trypsin. Others only act with one 
specific reaction, and are rapidly destroyed if the reaction changes from 
this. Examples of these are pepsin, only active in acid solution, and 
rapidly destroyed by a trace of alkalinity ; and the fat-splitting ferment 
of the pancreas, active only in alkaline or neutral solutions, and rapidly 
destroyed by acid. 

Accumulation of dissolved products of action—Accumulation of the 
products of the action of an enzyme in the solution acts unfavourably 
upon its continued action, slowing and finally altogether checking it.* 
This action may be to some extent prevented by removing the products 
formed by dialysis, or diluting them by the addition of water. In the 
latter case, however, the ferment is also diluted, and in the former, since 
the products of digestion in most cases have no very high diffusive 
power, the removal is very slow and incomplete. 

Removal of the digestive products by dialysis has, in addition, the 
disadvantage that the digestive solution is diluted by the osmosis, due to 


1 This term is that proposed by Sheridan Lea, Journ. Physiol., Cambridge and London, 
1890, vol. xi. p. 254. 

2¥,. Wittich, Arch. f. d. ges. Physiol., Bonn, 1869, Bd. ii. S. 193 ; 1870, Bd. iii. S. 339. 

3 Bidder u. Schmidt, ‘‘ Die Verdauungssafte, ete.” 

4 Briicke, Sitzwngsb. d. k. Akad. d. Wéssensch., Wien, 1862, Bd. xliii. 8S. 601; 
‘‘Vorlesungen,” Wien, 1885, Bd. i. S. 312; Cohnheim, Virchow’s Archiv, 1863, Bd. 
xxviii. S. 241 ; Kiihne, ‘‘ Lehrbuch der physiol. Chem.,” 1866, S. 39, 51, 52 ; Sheridan Lea, 
Journ. Physiol., Cambridge and London, 1890, vol. xi. p. 226. 


RATE OF ENZYMIC ACTION. get 


the osmotic pressure of the dissolved products. This water may, of 
course, be removed by subsequent evaporation at a low temperature, to 
avoid injuring the ferment, and again dialysing; but practically the 
diffusive power of the usual products of digestion is so low as to render 
a process of alternate dialysis and evaporation a tedious and almost im- 
possible method of freeing the solution completely of the products of 
digestion. This action of the accumulated products of digestion renders 
all digestive experiments carried out in glass essentially different from 
those which go on within the alimentary canal, where the products of 
digestion are removed as fast as they are formed. Not only must the 
natural process run more quickly, but there is no reason for assuming 
that it will even run qualitatively along the same lines. To take as an 
example the tryptic digestion of proteids. There are formed, as we shall 
see later, as end products, certain amido-acids, and a substance known as 
antipeptone, but long before these products are finally reached, soluble 
bodies are formed which can be shown to be capable of absorption and 
assimilation by the epithelial cells lining the intestine. 

Digestion experiments in vitro teach us the effects of digestion alone, 
sundered from its constant companion in the natural process—absorption ; 
and no perfect method has hitherto been devised whereby the effects of 
these two processes working in conjunction can be demonstrated. In 
the animal body the pure effect of digestion and absorption cannot be 
observed by studying the chemical composition of the intestinal contents 
and that of the contents of the channels of absorption, because the pro- 
ducts of digestion are not merely absorbed by the lining cells, but are 
profoundly modified by them in the process. Nor can the combined 
effect of digestion and absorption be studied in perfection by any known 
method of digestion and dialysis, because no artificial dialyser bears any 
but a very remote resemblance to the living intestine. A dialyser of 
parchment paper not only removes diffusible substances with infinite 
slowness compared with the intestinal epithelium,’ but it also acts on 
purely physical laws, diffusion taking place at rates directly proportional 
to the diffusion coefficients of the substances involved; while the living 
epithelium takes up with great avidity soluble substances which do not 
diffuse at all, and absolutely refuses passage to other very diffusible sub- 
stances, such as soluble salts of iron. That is to say, absorption by the 
cell is selective, being governed, indeed, by fixed and definite laws, pro- 
bably purely physical and chemical at bottom, but profoundly modified 
by the action of living protoplasm.” 


The effects of removal of products of digestion by dialysis has been studied 
by Sheridan Lea,® in the case of starch digestion by ptyalin, and proteid 
digestion by trypsin. The rapidity of dialysis was increased by mechanically 
raising and lowering the dialysing tube, and the rate of digestion and nature 
of products formed were compared with those in an exactly similar experiment 
arranged in a glass vessel. It was found (1) that the speed of digestion was 
in all cases increased, and (2) that before the process came to a standstill 
much more conversion took place than it was possible to attain to in glass, 
although complete conversion never took place in either case ; these differences 
were in every case more marked when concentrated solutions of the material 
to be digested were used, showing that the slower digestion and earlier stoppage 


1 Heidenhain, Arch. f. d. ges. Physiol., Bonn, 1888, Suppl. Heft, Bd. xliii. S. 60. 
2 For a further consideration of this subject, see ‘‘ Proteid Absorption,” p. 430. 
3 Journ. Physiol., Cambridge and London, 1890, vol. xi. p. 226. 


ViOLeis———2) 5 


322 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


in glass was due to accumulation in the solution of digested products. Similar 
experiments on the digestion of various forms of proteid, by pepsin and hydro- 
chloric acid, dialysing into hydrochloric acid of equal concentration, have been 
made by Chittenden and Amerman,' who found that removal of the products 
of digestion did not essentially favour peptonisation or alter the relative 
amount of albumose and peptone formed. 


Concentration of enzyme.—The rapidity with which zymolysis takes 
place naturally varies with the concentration of the enzyme in the 
solution, as well as with the concentration of the material to be digested, 
when this is soluble. Roberts found in the case of conversion of starch 
by the diastatie enzyme of the pancreas, that the amount of standard 
starch mucilage which can be converted in a given time and at a given 
temperature varies directly as the quantity of active solution employed. 

Schiitz? found in the digestion of proteid by pepsin, that when the 
solutions employed were sufficiently dilute, the amount of conversion 
was proportional to the square roots of the quantities of pepsin present. 
Any such rule can only hold within certain limits of concentration, a 
maximum being reached beyond which further concentration of the 
enzyme has no effect. 

Methods of estimating the relative activity of digestive solu- 
tions.—As none of the enzymes have been isolated in a pure condition, 
it follows that there is no means of estimating the absolute amount of an 
enzyme in solution. This is practically never a matter of any moment, 
but a problem which often presents itself in practical work on digestion 
is that of estimating the relative activities of two digestive extracts. 

The activity of a diastatic enzyme can be most accurately estimated 
by determining the amount of sugar (maltose) formed under given con- 
ditions in a given time by a given volume of the solution, acting on a 
measured volume of a standard solution of starch mucilage ; this, however, 
is a tedious and troublesome process, and for most purposes a sufficiently 
accurate process is that of observing when the starch has all disappeared, 
as shown by the failure of the iodine reaction. 


Such a method has been introduced by Roberts.? He varies the amount 
of the diastatic solution added until the “ achromie point” is reached within a 
period lying between the limits of four and six minutes. This achromic point 
is that point at which the starch solution ceases to give a yellow tinge with 
iodine, when accordingly the solution contains only achroddextrins and maltose. 
Roberts defines the diastatic value of a solution (denoted by the symbol D) 
by the volume in cubic centimetres of a standard starch mucilage which can 
be converted to the achromic point by 1 c.c. of that solution, acting during five 
minutes at a temperature of 40° C. 

The standard solution of starch mucilage must be prepared fresh ; it is 
made by stirring up 5 grms. of pure potato starch with 30 ¢.c. of water, and 
pouring slowly into nearly 470 ¢c.c. of water, which is kept boiling. The 
mixture is stirred and boiled for a few seconds, and finally accurately made up 
to 500 c.c., thus giving a standard solution (1 per cent.) of starch. 

The solution of iodine used is made by diluting 1 part of the lig. iodi of 
the Pharm. Brit. with 200 parts of water. 

In making a determination, one proceeds as follows :—Ten c.c. of the 
standard starch mucilage are diluted with distilled water to 100 cc. and 


* Journ. Physiol., Cambridge and London, 1893, vol. xiv. p. 483. 
2 Zischr. f. physiol. Chem. , Strassburg, 1885, Bad. ix. 8. 577. 
8 Diastasimetry, In “Digestion and Diet,” London, 1891, p. 68. 


RELATIVE ACTIVITY OF DIGESTIVE SOLUTIONS. 323 


warmed to 40° C.; a known volume of the diastatic solution to be tested is 
next added, say 1 c.c., noting the time; drops of the solution are then tested 
from time to time, say at intervals of ten seconds, with drops of iodine on a 
porcelain slab until no yellow tinge is produced, and the interval of time 
which has elapsed is noted. By altering the amount of diastatic solution 
added, as a result of preliminary experiment, this time must be arranged to lie 
between four and six minutes; if the time is shorter than four minutes, an 
error of a few seconds in determining the time of conversion makes too large a 
percentage error, or if it be much longer than six minutes the transition is too 
gradual at the end for the eye to accurately catch the achromic point. If v 
be the volume in cubic centimetres of diastatie solution added, m the time to 
reach the achromic point in minutes, and D the diastatic value of the solution 


as above defined—then, D = = = 


This value of D gives a measure of the activity of a given diastatic solution, 
in terms of a standard which can be easily reproduced at any time to measure 
the activity of another diastatic solution, and so comparable results may be 
obtained. 


Various methods are in use for determining the relative activity of 
proteolytic solutions. 


The earliest method is that first introduced by Bidder and Schmidt, and 
used in various modifications by other experimenters. It consists in deter- 
mining the weight of proteid dissolved in equal times, by equal volumes of the 
digestive liquids added to equal volumes of a proper digestive medium. The 
method is oftenest used for relative determinations of pepsin, when the 
medium used is hydrochloric acid solution of 1 or 2 per mille, but it may also 
be used for trypsin, when } per cent. sodium carbonate can be used as a 
medium. The digestive solutions are placed in a bath at 40° C., and when 
they have acquired the temperature of the bath, equal weighed portions of 
equally finely subdivided hard-boiled white of egg (obtained by passing through 
gauze netting) are added to each, and digestion allowed to proceed for the same 
period in each case, say twenty-four hours ; the liquids are then filtered, and the 
residues left undigested are washed, dried, and weighed ; a third equal quantity 
of the white of egg used is also dried and weighed without previous digestion ; 
and from the figures so obtained the amounts of dissolved, white of egg are 
deduced, and these are taken as representing the comparative peptonising 
values of the two samples. 


Briicke’s+ method—This method consists essentially in diluting the 
two proteolytic solutions to be compared with the same medium (1 per 
mille HCl) in two series, and then picking out those two members in 
each series which are most nearly equal; from the relative dilution of 
these two the comparative activity of the two original solutions easily 
follows. 


Vessels. Pepsin Solution of Acidity, Water of Acidity, 
1 per Mille. 1 per Mille. 

1 16 0 

2 8 8 

3 4 12 

+ 2 14 

5 1 15 

6 0-5 155 

7 0°25 15°75 


1 «* Vorlesungen ueber Physiologie,” Wien, 1885, Aufl. 4, Bd. i. S. 311. 


324 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


Hydrochloric acid is added to the two pepsin solutions, until the acidity 
represents 1 grm. of hydrochloric acid per litre. These are then diluted in a 
series of vessels with hydrochloric acid (1 per mille) according to the foregoing 
scheme ; the figures represent volumes, say cubic centimetres. 

A corresponding series of dilutions of the second solution is also prepared, 
and in the vessels of both series a shred of fibrin! is digested for a given time. 
At the end of the time, correspondingly advanced specimens are picked out in 
the two series, especial attention being paid to the more dilute samples, which 
give the truer indications, and the comparative power of the two solutions 
easily follows. For example, if No. 3 in one series corresponds to No. 5 in the 
other, the latter is four times as powerful as the former ; a closer approximation 
can then evidently be obtained by a second experiment. 

Grinhagen’s* method.—F¥ibrin is swollen out by placing it for some hours 
in dilute hydrochloric acid. Equal weighed portions of this swollen fibrin are 
placed in similar filters. Over each portion an equal volume, say 1 c.c., of the 
various digestive solutions to be compared are poured. Soon the fibrin begins 
to dissolve and drop from the funnels, dissolving in the dilute acid which had 
previously swollen it. From the measured amounts dropping in equal times 
from the different funnels, or by counting the rate of the drops, the compar- 
ative activities of the various solutions can be determined. This method 
evidently cannot be used for trypsin. 

Gritzner’s® method.—Also cannot be used for trypsin, but is one of the best 
methods for pepsin. It is a colorimetric method, and consists in measuring 
the velocity with which the solution under examination dissolves fibrin stained 
uniformly with carmine, by means of the depth of tint imparted to the solution 
by the finely divided particles of carmine, which are set free in the solution at 
a rate proportional to that of solution of the fibrin. 

The method is best carried out by comparing the depth of the tints 
produced at observed time intervals with those of a number of standard solu- 
tions of carmine. The methods employed in preparing the stained fibrin and 
these standard tints are as follows :—The fibrin is first well washed in a stream 
of running water accompanied by kneading, and then placed for twenty-four 
hours in a bath of weakly ammoniacal 0°25 per cent. carmine solution,® the 
volume of staining fluid being large compared with that of the mass of fibrin 
to be stained, and the latter being pulled into small pieces, so as to ensure 
thorough and uniform staining. After staining for twenty-four hours, the 
fibrin is removed from the staining bath and washed well in a stream of 
running water until it ceases to colour it. Before using for a digestion experi- 
ment, the coloured fibrin in small pieces is immersed in about five times its 
volume of 0-2 per cent. hydrochloric acid for thirty to sixty minutes; this 
swells it up to a clot-like mass, and it is used in this condition, pieces of 
approximately equal size being placed in equal volumes of the various digest- 
ive fluids to be compared, contained in equal-sized test tubes. 

The scale of comparison tints may be prepared by adding, in varying pro- 
portion, a glycerin solution containing one-tenth per cent. of carmine, to water 
in test tubes of equal size; thus, to 19°9 ec.c. of water are added 0-1 ec. of 
one-tenth per cent. glycerin-carmine solution ; to 19°8 ¢.c. of water, 0°2 c.c. of 
the same glycerin-carmine solution; and so on, finishing with a solution 


1 Approximately of equal size ; a slight difference has no appreciable effect. 

2 Arch. f. d. ges. Physiol., Bonn, 1872, Bd. v. S. 203. For a method of adopting this to 
experiment at body temperature, see Griitzner and Ebstein, zbid., 1874, Bd. viii. S. 122. 

8 Ibid., 1874, Bd. viii. S. 452 ; ‘‘ Neue Untersuch. ii. Bildung u. Ausscheid. des Pepsins,” 
Habilitationsschrift, Breslau, 1875. 

*It may advantageously be left in water over night to remove accompanying hemo- 
globin. 
pie Prepared by dissolving 1 grm. of carmine in a small velume of dilute ammonia and 
making up to 400 c.c. with water ; the solution should only very faintly smell of ammonia, 
and if necessary must be left exposed to the air until the odour of ammonia almost disappears. 


RELATIVE ACTIVITY OF DIGESTIVE SOLUTIONS. 325 


of 19 cc. of water and 1 c.c. of glycerin-carmine solution. In this manner 
ten standard tints are obtained, the values of which correspond to the numbers 
1 to 10; these are mounted in a stand against a uniform white background, 
and are used to compare with the results of digestion, after equal intervals 
of time. For example, if after thirty minutes’ digestion the tint of one test 
tube corresponds most closely to that of Standard 2, while that of another 
corresponds to Standard 6, the latter is three times as powerful a digestive 
solution as the former. The digestive solutions should be so diluted that they 
act somewhat slowly, because after a time a maximum tint obtains, and then 
the weaker digestive fluid catches up on the other; the farther apart from 
this maximum the measurements are taken the better. Also, if a close approxi- 
mation to the comparative amounts of pepsin in two solutions is required, 
after a preliminary experiment the stronger of the two must be diluted 
experimentally until its action is equal to that of the other, then the pro- 
portion of dilution gives the proportionate strength in pepsin of the two 
solutions. This determination may be most speedily attained by making a 
simultaneous series of dilutions of the stronger solution, and comparing the 
strength of their action with that of the other solution or a series made 
from it. 

Two tubes of equal speed of action are picked out, and from their dilutions 
the comparative richness in pepsin of the original fluid easily follows. Griitzner’s 
method may also be employed without a scale of standard tints, by stopping 
digestion after an equal period, and then diluting the stronger solution until 
its tint becomes equal to that of the weaker, or by carrying out two series 
in aliquot dilution of the two solutions to be compared, and picking out 
equally advanced members of the two series. In case the comparison is made 
with solutions of unequal power, it must be remembered that what is measured 
is the comparative digestive power and not the comparative strength of the 
solutions in pepsin, because the two are not proportional ;+ in all cases it is 
preferable, for accuracy, to prepare solutions from the originals of equal power, 
and from the amount of dilutions of these to deduce the comparative strength 
in pepsin of the originals, as indicated above. 

Mette’s method.2—This method is stated by Samojloff to yield exact 
results. It consists in filling fine glass tubes of 1 to 2 mm. in diameter with 
fluid white of egg, then coagulating by heat, and cutting off pieces of equal 
length. These are placed in the digestive solutions at body temperature, and, 
after the lapse of a certain interval, the length of white of egg digested off is 
measured, which gives a measure for the comparative activities of the two 


fluids. 


Griitzner * has also introduced methods for comparing the diastatic 
and fat-splitting powers of pancreatic extracts. 


That for diastatic action closely resembles Griinhagen’s method for proteo- 
lytic action. Equal volumes of 3-4 per cent. starch paste are placed on similar 
filters, through which they do not filter until dissolved ; to each filter 0-2 to 
0°3 c.c. of the extracts to be compared are next added, when solution of the 
starch takes place at a rate proportional to the amount of enzyme present, 
and a comparison of the amounts filtering through in a given time supplies 
a measure for the activities of the extracts. 

The method of comparing the fat-splitting powers of different extracts 
consists in allowing the extracts to act on an emulsion in presence of litmus, 
and noticing the time and amount to which the latter is turned red by the 
acid developed. The emulsion recommended is made by mixing 10 parts of 


1 See Schiitz’s law, p. 322. 
2 Samojloff, Arch. de se. biol., St. Pétersbourg, 1893, tome ii. p. 707. 
3 Arch. f. d. ges. Physiol., Bonn, 1876, Bd, xii. S. 293, 303. 


326 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


oil of almonds, 5 parts of gum-arabic, and 35 parts of water. A solution 
of litmus is prepared of such concentration and reaction that it shows a violet 
colour when placed in test tubes about a centimetre in diameter in front 
of white paper; in each test tube 10 c.c. of this dilute litmus solution are 
placed ; to each five drops of emulsion are added ; then equal volumes of each 
of the pancreatic extracts to be compared. From the times in which an equal 
amount of red develops in the litmus in each case, the richness of the extracts 
in fat-splitting ferment may be determined. Or a series of determinations 
for each extract, using a varying quantity of it, may be made, and the 
members of each series compared. 


The condition of the material to be digested has also a profound 
effect upon the rapidity. The factors of most moment are— 

1. Whether the material is fluid or solid. 

2. Whether it has previously been heated (cooked) or not. In the 
case of starch, previous heating and formation of a starch paste shortens 
the process in the ratio of hours to minutes; in the case of proteids, 
previous heat coagulation slows the after process of digestion. 

3. Materials which must first be dissolved, and must therefore be 
attacked from the outside, are digested more quickly when in a finely 
subdivided condition. 


Classification of Enzymes. 


Digestive Fluid in Concise Description of 


‘a Enzyme. Name of Enzyme. : eos 4 
Olesich Bnzyme C which found. Specific Action. 


1. Ptyalin Saliva Convert amyloses 
(starches and glyco- 
Miastah ae , ig ae gen) into dextrins 
pone. 2. Amylopsin Pancreatic juice maltose, and isomal- 
tose, accompanied by 

a trace of glucose. 


1. Pepsin Gastric juice Converts proteids into 
albumoses and pep- 
tones. 
Proteolytic . . 
2. Trypsin Pancreatic juice Converts proteids into 
albumoses, peptones, 
and amido-acids. 


Fat-splitting or Steapsin or Pancreatic juice Splits up neutral fats 
steatolytic pialyn into fatty acids and 

| glycerin. 
1. Rennin Gastric juice Coagulates milk, con- 


verting caseinogen in 
presence of calcium 
salts into casein. 


2. Anwnnamed | 
ferment occur- 
ring in pan- 
creatic juice, 
which also 
coagulates 
milk 


Coagulating 


SPECIFIC ACTION OF ENZYMES. 327 


Specific action of enzymes.—The different enzymes are specific in 
their action; that is to say, each enzyme only acts on one class of 
material and acts on it in a determinate manner, producing certain 
specific substances as the result of that action. The table on p. 326 is 
a classification of the digestive enzymes according to their specific action. 

Description of the digestive enzymes.—The digestive enzymes 
may be here most conveniently treated of according to their occurrence 
in the various digestive secretions, because of the description of the mode 
of their separation, where more than one is found in the same digestive 
fluid. Their action on the different classes of foodstuffs and the products 
formed thereby will be considered afterwards. 

Ptyalin.—In the saliva of manyanimals, and especiallyin the herbivora, 
a diastatic enzyme is found, to which, soon after the discovery that saliva 
possessed such an action, the name ptyalin was applied. In fishes 
and in cetacea no salivary glands are present,? and in some other 
animals the salivary secretion possesses no diastatic action ; for example, 
the saliva of the dog has no diastatic action, and the same statement is 
made for the typical carnivora in general.? In man, the secretion of both 
the parotid and submaxillary glands has a diastatic action. At birth the 
ferment is only found in the parotid; it makes its first appearance in 
the submaxillary two months later.t In the horse the secretion leaves 
the parotid with the diastatic ferment still in the condition of a 
zymogen, from which the enzyme is set free by treatment with alcohol 
or by contact with unfiltered air.® 

Ptyalin was first separated from saliva in an impure form by 
Mialhe,® by precipitating filtered saliva with excess of absolute alcohol. 
A scanty flocculent proteid precipitate is so obtained, which carries 
down the ptyalin mechanically. Mialhe showed that. this precipitate, 
which was insoluble in strong alcohol, but partly soluble in water or 
weak alcohol, possessed when dissolved the diastatic power of the 
original saliva. From its supposed identity with the diastase of malt, 
he called it diastase animal ow salivaire, aud used the term ptyalin as a 
synonym. It is now known that ptyalin and malt diastase, though 
alike in their action upon starch, are not identical. This is shown best 
by the difference in the reaction of the two enzymes to changes in 
temperature. According to Roberts,’ saliva possesses a maximum 
action between the temperatures of 30° and 45° C., and, according to 
Kjeldahl’ the optimum temperature is 46° C., while the enzyme is rapidly 
destroyed by a temperature lying between 65° and 70° C.2 On the 


1 Leuchs, Arch. f. d. ges. Naturl., Niirnberg, 1831 ; Schwann, Ann. d. Phys. u. Chem., 
Leipzig, 1836, Bd. xxxvili. S. 358. 

* According to Krukenberg (‘‘Grundziige einer vergleich. Physiol. der Verdauung, 
1882, S. 67), in some fishes the secretion of the mucous glands of the mouth possesses a 
diastatic action; the same is true of the mucous secretion of the frog’s mouth. 

3 Griitzner, Arch. 7. d. ges. Physiol., Bonn, 1876, Bd. xii. S. 285; Bunge, ‘‘ Lehrbuch 
der physiol. Chem.,” Leipzig, 1894, Aufl. 3, S. 140; Neumeister, ‘‘ Lehrbuch der 
physiol. Chem., etc.,” Jena, 1893, Th. 1, S. 122. 

4 Zweifel, ‘‘ Untersuch. ueber den Verdauungsapparat. der Neugeborenen,” Berlin, 
1874. See also Schiffer, Jahresh. ti. d. Fortschr. d. Vhier-Chem., Wiesbaden, 1872, Bd. 
ii. S. 205 ; Korowin, ibid., 1873, Bd. iii. S. 158; Bayer, ibid., 1876, Bd. vi. S. 172. 

® Goldschmidt, Ztschr. f. physiol. Chem., Strassburg, 1886, Bd. x. S. 273. 

6 Compt. rend. Acad. d. sc., Paris, 1845, tome xx. pp. 654, 1483. ° 

* « Digestion and Diet,” London, 1891, p. 79. 

8 Abstract in Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1879, Bd. ix. S. 381. 

® Roberts, Zoc. cit. ; Kiihne states that saliva loses its activity at a temperature of 
60° C. (‘‘ Physiol. Chem.,” S. 21). 


39 


328 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


other hand, the optimum temperature for malt diastase lies at 50° to 
56° C.;1 the activity does not greatly diminish until 60° C. is passed, and 
then rapidly decreases and disappears, the ferment being destroyed by a 
temperature of 80°C. Malt diastase is also much more sensitive to the 
presence of salicylic acid than is ptyalin, being stopped by the presence 
of 0:05 per cent., while ptyalin is first affected by 01 per cent., and not 
completely stopped until a strength of 1 per cent. is reached.” 

There is unfortunately no such certainty as to the identity or non- 
identity of ptyalin and amylopsin (the diastatic ferment of the pancreas), 
which is also called ptyalin by some authors. By others, the two 
enzymes are accounted different, because (a) the pancreatic action is more 
intense and complete, and (b) there are certain differences in the 
products formed by the action of the two enzymes.* It is, however, 
questionable whether these effects may not be entirely produced by 
differences in concentration in the two cases of one and the same 
ferment. In their behaviour to change of temperature and reaction the 
two enzymes are identical; the rate of conversion of starch into other 
substances depends on the concentration of the enzymes in the solution ; 
and with regard to differences in the products formed, it is not denied 
that in prolonged salivary digestion a small quantity of dextrose is 
formed, it is only claimed that larger quantities of dextrose are 
formed in a shorter time® by the action of the diastatic enzyme of the 
pancreas; this again is a difference in degree and not in kind, and may 
well be due to a difference in concentration of enzyme. 

Cohnheim ® obtained ptyalin in a purer form, that is, more free from 
admixed proteids, by a method closely resembling that of Briicke for 
pepsin, and consisting essentially in producing a precipitate of tricalcic 
phosphate in the saliva by the addition of phosphoric acid followed by 
milk of lime; this precipitates mechanically ptyalin and proteid, the 
ptyalin dissolves more easily than the proteid on afterwards washing 
the precipitate with distilled water, and may in this way be separated. 

The solution so obtained was actively diastatie, but yet gave none of 
the usual proteid reactions, was not coagulated on boiling, gave no 
reactions with nitric acid, mercuric chloride, tannin, iodine, or acetic acid 
and potassium ferrocyanide. The ptyalin precipitated from it was not 
a pure substance, but contained chlorides and phosphates of sodium and 
calcium. 

Excess of alcohol caused a flocky precipitate of phosphates, and an 
amorphous granular substance coloured yellow by iodine. Dried at a low 
temperature, this precipitate furnished a white powder, only slightly 
soluble in water, which retained its diastatic action for months. 

A very active material may also be obtained by v. Wittich’s method 


1 Chittenden and Martin, Stud. Lab. Physiol. Chem., New Haven, 1885, vol. i. p. 117 ; 
abstract in Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1885, Bd. xv. 8S. 263; 
Lintner and Eckhard, Journ. f. prakt. Chem., Leipzig, 1891, N. F., Bd. xli. S. 91; Stutzer 
and Isbert, Zéschr. f. physiol. Chem., Strassburg, 1888, Bd. xii. S. 72. 

> Jul. Miiller, Journ. f. prakt. Chem., Leipzig, 1875, N. F., Bd. x. S. 45. 

° Neumeister, ‘‘ Lehrbuch der physio]. Chem.,” Jena, 1893, Th. 1, S. 147. 

4 See Sheridan Lea, ‘‘ Chemical Basis of the Animal Body,” London, 1882, p. 57. 

° Lea, however, found no dextrose, but only maltose, in his experiments quoted on p. 394. 
See also Brown and Heron, Proc. Roy. Soc. London, 1880, No. 204, p. 393; Musculus and 
Gruber, Ztschr. f. physiol. Chem., Strassburg, 1878-9, Bd. ii. S. 177; Musculus and v. 
Mering. ibid., S. 403; v. Mering, zibid., 1881, Bd. v. S. 185. 

§ Virchow’s Archiv, 1863, Bd. xxviii. S. 241. Compare Sundberg’s statement as to 
similar precipitation of pepsin by alcohol and not by tannic acid, p. 316, 


3 


PIVALIN, 329 


of extracting the salivary glands with glycerin, precipitating the 
glycerin extract with excess of alcohol, washing with strong alcohol, 
and then extracting with water. 

Effects of reaction. — A knowledge of the effects of change of 
reaction on the amylolytic activity of ptyalin, apart from its intrinsic 
interest, possesses considerable importance from the bearing it has on 
the natural process of digestion of starch, and for this reason probably 
the subject has attracted the attention of a great number of workers. 
Ptyalin is secreted in an alkaline fluid, the saliva, and after a few 
seconds admixture with the food passes with it into the stomach; here 
its alkaline reaction is lessened by the gastric secretion, and finally 
replaced by an acid reaction. The amount of starch changed by the 
ptyalin will depend on the effect of this gradual diminution in alkalinity 
on its activity, and if the activity is decreased thereby, on the rate at 
which progress is made towards an acid reaction. 

It was formerly supposed that ptyalin was only active in a fluid 
of alkaline reaction, that it was im consequence only active during 
the few seconds of mastication, while the food remained in the 
mouth, and was instantly destroyed on coming in contact with 
gastric juice. More recent observations have, however, shown that 
the importance of saliva as a digestive fluid is much underrated by 
such a view. 

The diastatic action of ptyalin attains a maximum when the reaction 
of the fiuid containing it is neutral, or even faintly acid, provided the 
acidity is due to acid combined with proteid. Even mere traces of free 
acid, however, lessen and rapidly destroy its activity. Sodium carbonate 
added to neutralised saliva decreases its activity, and in greater 
quantity arrests it; here, again, proteids present in solution play a 
protecting part, and by combining with the alkali prevent its injurious 
action on the ferment. A solution of ptyalin free of proteid would 
therefore probably act best in a neutral fluid, and would be quickly 
destroyed by either an acid or alkaline reaction, due to acid or alkali 
uncombined with proteid.” 

The diastatic action of the saliva, therefore, continues in the stomach 
during and after a meal until (1) the alkali of the saliva has been 
neutralised, (2) the proteid present in solution has been satisfied, and 
(3) a trace of free hydrochloric acid remains in excess. According 


1 Jacubowitsch, Lehmann’s ‘‘ Zoochemie,” in Gmelin’s ‘‘Handbuch der Chem.,” 
Heidelberg, 1858, Bd. viii. S. 22; Paschutin, Arch. f. Anat. u. Physiol., Leipzig, 1871, 
S. 366 ; Hammarsten, Jalresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1871, Bad. i. 
S. 35; Briicke, Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1872, Abth. 3; Watson, 
Trans. Chem. Soc., London, 1879, p. 539; Chittenden and Griswold, Am. Chem. Journ., 
Baltimore, 1881, vol. iii. p. 305; Falk, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 
1881, Bd. xi. S. 444; Langley, Journ. Physiol., Cambridge and London, 1880-2, vol. iii. 
p- 246; Nylén, Jahresb. tui. d. Fortschr. d. Thier-Chem., Wiesbaden, 1882, Bd. xii. S. 
241 ; Chittenden and Ely, Am. Chem. Journ., Baltimore, 1882, vol. iv. ; Journ. Physiol., 
Cambridge and London, 1882, vol. ili. p. 327; Detmar, Zétschr. f. physiol. Chem., 
Strassburg, 1882, Bd. vii. S. 1; Langley and Eves, Journ. Physiol., Cambridge and 
London, 1883, vol. iv. p. 18; Chittenden and Smith, Chem. News, London, 1885, vol. 
liii.; Stud. Lab. Physiol. Chem., New Haven, 1885, vol. i. p. 1; John, Centralbl. f. klin. 
Med., Bonn, Bd. xii.; Schlesinger, Virchow’s Archiv, 1891, Bd. exxy. S. 146 ; Schierbach, 
Skandin. Arch. f. Physiol., Leipzig, 1892, Bd. iii. S. 344; Ebstein u. Schulze, Virchow’s 
Archiv, 1893, Bd. exxxiv. S. 475. 

2It is generally held that ptyalin acts best in neutral solution or with a faint acid 
reaction, due to acid combined with proteid ; but there are slicht differences of opinion as to 
where the exact optimum point lies, for which the original papers should be consulted, 
especially those by Langley and by Chittenden and their co-workers. 


330 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


to the observations of van d. Velden! there is no free hydrochloric acid 
found in the stomach until, on an average, three-quarters of an hour 
after a carbohydrate meal. During this time the diastatic action of the 
saliva must continue, and probably during most of the interval more 
intensely than it would with its natural reaction. In this stage gastric 
juice removed by the pump possesses a diastatic action on starch, but 
later, when free acid is present, even when saliva is added to it, has no 
such power. After all the proteid present im solution in the stomach 
has been combined with the acid first secreted in the gastric juice, 
and still more acid is secreted which remains free, the ptyalin not only 
becomes inert, but is rapidly destroyed, and does not come into action 
again after the acid of the gastric juice is neutralised in the small 
intestine.” 

Free organic acids also act destructively on ptyalin; the concentration 
of acid required is greater than in the case of hydrochloric acid, and 
varies with the particular acid as well as with the concentration of the 
ferment in the solution. Different neutral metallic salts possess different 
actions; some diminish the activity, such as mercuric chloride, which 
even in a concentration of 0-005 per cent. is sufficient to stop all action; 
others increase it when present in small quantity, such as magnesium 
sulphate up to 0-025 per cent., but have an opposite effect in greater 
concentration.? Carbolic acid does not produce much effect, digestion 
with 5 per cent. solution for some hours being required to destroy the 
ferment.* 

Pepsin.—Pepsin is very widely distributed in the animal kingdom , 
it is found in the gastric juice of all vertebrates, with the possible excep- 
tion of some fishes.> In the frog it is found chiefly in the cesophagus.® 
In the crayfish a yellowish- brown fluid is found in the mouth, of strong 
acid reaction, which digests fibrin readily.7 And in many insects an acid 
proteolytic secretion has been observed. Similar acid proteolytic secre- 
tions are also known in the vegetable kingdom, such as those which may 
be obtained by stimulating the leaves of insectivorous plants.§ Whether 
these acid proteolytic ferments of the invertebrates and plants are 
identical with pepsin is not known with certainty, but they are very 
sunilar in their action. 

Pepsin is found in the stomach of the herbivora at birth, and in 
some other animals, including man; in others, it first appears two or 
three weeks after birth, as in the dog and eat 

The different regions of the stomach do not, on extraction, yield 


* Zischr. J. physiol. Chem., Strassburg, 1879, Bd. iii. S. 205. 

*See Langley, Journ. Physiol., Cambridge ‘and London, 1882, vol. iii. p. 246 ; Nylén, 
Jahresb. i. d. Fortschr. d. Thier-Chem.. W. iesbaden, 1882, Bd. xii. S. 241; and other 
authorities quoted above. Opposite results were obtained by Cohnheim, Vir chow’s Archiv, 
1863, Bd. xxviii. S. 248 ; Schiff, ‘‘ Lecons sur la digestion,” tome i. p. 162 ; and Dufresne, 
Compt. rend. Acad. d. sc., Paris, 1879, tome Ixxxix, p- 1070. 

3 Nasse, Arch. f. d. ges. Physiol., Bonn, 1875, Bd. xi. S. 138 ; Chittenden and Painter, 
Stud. Lab. Physiol. Chem., New Haven, 1885, vol. i. p- 52. 

4 Plugge, Arch. f. d. ges. Physiol., Bonn, 1872, Bd. v. S. 550. 

> Hammarsten, «Lehrbuch der Physiol. Chem.,” Wiesbaden, 1895, Aufl. 3, S. 234. 

§ Swiecicki, Jahresb. ii. d. Fortschr. d. Thier-Chem.., Wiesbaden, 1876, Bd. vi. S..172. 

7 Hoppe- -Seyler, ibid., S. 170. 

8 Darwin. ‘ Insectiv orous Plants’? ; Goebeb and Loew, Chem. Centr.-Bl., Leipzig, 1893, 
Bd. ii. S. 1065. 

® Moriggia, Untersuch. z. Naturl. d. Mensch. u. d. Thiere, 1876, Bd. xi. S. 455 ; 
Hammarsten, Beitr. z. Anat. u. Physiol. als Festgabe C. Ludwig, Leipzig, 1874, S. 116; 
Zweifel, “Ueber d. Verdauungsapparat der Neugeborenen,” Berlin, 1874. 


PEP SIN. oan 


equal amounts of pepsin: the pyloric end always contains much less 
than the fundus or the cardiac end, but is never quite devoid of pepsin. 
It was formerly held by some observers that the pepsin found in the 
pyloric end was due to infiltration by the secretion from the glands of 
the remainder of the stomach, but the secretion obtained from pyloric 
fistulee contains pepsin which can only be secreted by the glands of this 
region of the stomach." 

Effects of temperature.—Pepsin in neutral solution is destroyed by a 
temperature of 55° C.; in a solution containing two parts per thousand 
of hydrochloric acid it is not destroyed at this temperature, but is 
destroyed in five minutes at a temperature of 65° C. By the addition 
of peptones or certain salts it is so protected that it is only destroyed 
in an equal time by a temperature of 60° 0.2 According to v. Wittich,* 
the maximum rapidity of action is found between 35° and 50° C., and 
the rapidity of destruction by elevated temperature (as in the case of 
ptyalin) is dependent on the amount of dilution of the ferment, and the 
duration of the high temperature. The more dilute the pepsin solution 
the more quickly it is destroyed, and the lower the limit of temperature 
necessary. Pepsin is still faintly active at 0° C.* 

Effects of reaction —Pepsin is only active in acid solution; the most 
effective acid is hydrochloric acid, but other acids are also capable of 
setting it in action in varying degree. The most energetic of the other 
acids are nitric, lactic, and phosphoric, followed at some distance by 
sulphuric, acetic, oxalic, and tartaric acids. The most effective acids 
seem also to be those which most easily swell up fibrin. Acid sodium 
phosphate does not confer activity on pepsin.° 

The amount of acidity required for optimum activity varies greatly 
with the form of proteid to be digested; thus Briicke® gives for 
fresh fibrin ‘08 per cent., but for heat-coagulated fibrin ‘12 to 16 per 
cent. 

Supposed compound of pepsin and hydrochloric acid.—The hypothesis 
has been put forward, that the pepsin and hydrochloric acid in gastric 
juice are united to form a loose compound “ pepsin - hydrochloric 
acid.” 

There is no clear evidence in favour of the existence of such a 
compound. It is said to be precipitated from gastric juice by the 
soluble salts of lead and mercury, and to be re-obtainable unaltered 
from the precipitate by decomposing with sulphuretted hydrogen. But 
it is certain that both the acid and pepsin would be thrown down by 
such salts, and there is no reason to suppose that they are not thrown 
down separately instead of as a compound, and recovered together again 
on decomposing the mixed precipitate. A second argument, that the 
supposed compound acid can be decomposed by strong acids or alkalies, 
and that the pepsin so separated does not again become active on the 


1 See Ebstein and Griitzner, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1872, 
Bd. ii. S. 210; 1873, Bd. iii. S. 169; 1874, Bd. iv. S. 236; Klemensiewicz, ibid., 1875, 
Bd. v. S. 162; Heidenhain, ibid., 1878, Bd. viii. S. 245 ; Klug, ibid., 1894, Bd. xxiv. 
S. 334; Akermann, Skandin. Arch. f. Physiol., Leipzig, 1895, Bd. v. S. 184. 

2 Biernacki, Ztschr. f. Biol., Miinchen, 1892, Bd. xxviii. S. 49. 

3 Arch. f. d. ges. Physiol., Bonn, 1869, Bd. ii. S. 193 ; 1870, Bd. iii. 8. 339. 

4 Flaum, Zischr. f. Biol., Miinchen, 1892, Bd. xxvii. 8. 453. 

5 Maly, Hermann’s ‘‘ Handbuch,” Bd. v. (2) 8. 73. 

6 Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1859, Bd. xxxvii. S. 131; Hammarsten 
gives for fibrin 0°8 to 1; for myosin, casein, and vegetable proteid, 1 ; for hard-boiled proteid, 
2°5 parts per litre. —“ Lehrbuch,” Aufl. 3, S. 238. 


330 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


addition of hydrochloric acid, because the compound is not re-formed, 
meets a simple answer in the statement that the pepsin is permanently 
destroyed by the strong acid or alkali used. A strong argument against 
any such compound is that the concentrations of different acids causing 
equal activity in pepsin are not proportional to the chemical equivalents 
of the acids, as might be expected if the acids entered into chemical 
combination with the pepsin." 

Pepsin is very rapidly destroyed by solutions of alkalies or alkaline 
salts.2 The principal conditions which influence the rate of destruction 
of pepsin by sodium carbonate are—the strength of the solution of the 
alkaline salt, the time during which it is allowed to act, the temperature 
of the mixture, and the amount of proteid present. The mere act of 
neutralising an acid pepsin solution may destroy a considerable part of 
the pepsin. When equal volumes of a fluid containing pepsin and of a 
1 per cent. solution of sodium carbonate are well mixed, the greater part 
of the pepsin is destroyed in fifteen seconds; in a neutralised acid 
extract of the gastric mucous membrane of a cat, the amount thus 
destroyed may be 31 of the whole. Even very dilute sodium carbonate 
(005 per cent.) will cause an appreciable destruction of pepsin in one 
or two hours at the body temperature, provided proteids are present 
in small amount only. 

Proteids lessen the rate of destruction of pepsin, probably by 
combining with the alkali or alkaline salts, for the greater the amount 
of sodium carbonate present the greater must be the amount of proteid 
to lessen appreciably the destruction. In the presence of ‘5 per cent. 
sodium carbonate, less than 25 per cent. of peptone has very little effect, 
and even 2°5 per cent. of peptone does not prevent the greater part of the 
pepsin from being destroyed. Thus, in the presence of 2°5 per cent. 
peptone, seven-eighths of the pepsin in an extract of a cat’s gastric 
mucous membrane may be destroyed at 17° C. by “5 per cent. sodium 
carbonate in sixty seconds. Pepsin prepared from a frog is less rapidly 
destroyed than pepsin prepared from a mammal. Carbonic acid destroys 
pepsin also, but less rapidly than it destroys pepsinogen.® 

Solutions of salts of the heavy metals weaken or entirely remove the 
activity of pepsin solutions, according to the amount added. This effect 
is probably due to the enzyme being mechanically carried down in the 
usual fashion by the precipitate formed between heavy metal and pro- 
teid. The neutral salts of the alkalies and alkaline earths, when added 
(even in small quantity) to solutions of pepsin, decrease the activity. 
Thus Al. Schmidt # found that salt-free proteid dissolved in a few seconds 
in salt-free pepsin solution, but on the addition of 05-06 per cent. of 
sodium chloride the time of solution was increased three to ten times. 
Hydrobromic and hydriodic acids in large doses, and to a still greater 
extent their potassium salts, delay peptic digestion. Sulphurous acid stops 
peptic digestion, but arsenious and hy drocyanic acids, except in large 
amounts, have little effect. Carbolic acid in small quantities has also 
little effect, but acts injuriously in greater concentration. Salicylic acid 


1 Davidson u. Dietrich, Arch. f. Anat. u. Physiol., Leipzig, 1860, S. 688; Putzeys, 
Jahresb. ti. d. Fortschr. d. Thier-Chem., Wiesbaden, 1877, Bd. vii. 8. 279; Hahn, Virchow’s 
Archiv, 1894, Bd. exxxvii. S. 597. 

2 Langley, Journ. Physiol., Cambridge and London, 1882, vol. iii. pp. 253, 283 ; 
Langley and Edkins, 7bid., 1886, vol. vii. p. 371. 

° (Juoted from Langley ‘and Edkins, loc. cit. 

4 Jahresb. wi. d. Fortschr. d. Thier-Chem., Wiesbaden, 1876, Bd, vi. S. 23. 


PEPSIN. 333 


was formerly credited with a powerful checking action, but, as shown 
by Kine,’ while powerful in preventing the growth of bacteria, this 
acid has no appreciable action, especially in small quantity, on the un- 
organised ferments. Pepsin is much more rapidly destroyed by standing 
under strong alcohol than are the other enzymes. 

Anything which prevents swelling of the proteid by the acid retards 
the progress of peptic digestion. Briicke? states that fibrin tied tightly 
round with a thread, so that it cannot be so easily swollen by the acid, 
is digested much more slowly. Adding a sufficient amount of neutral 
salt also slows the digestion, probably from a similar cause, the salt 
preventing the imbibition of acid by the fibrin. The comparative slow- 
ness of digestion of heat-coagulated proteid, such as coagulated white of 
egg, may also be due to a like cause, for such a form of proteid does not 
swell up with acid. Finally, stronger acid than the optimum strength 
does not cause so much swelling, and this may in part be the reason of 
the slowing due to this cause. 

Variation in rapidity with form of proteid.—the time of digestion 
by pepsin varies enormously with the nature and condition of the pro- 
teid to be digested; coagulated white of egg requires almost as many 
hours as unboiled fibrin does minutes. The comparative rate of pepton- 
isation of coagulated and non-coagulated white of egg has been much 
investigated, and with varying results. According to Waurinski,? these 
variations are due to want of uniformity in the concentration of acid 
employed as a digesting medium; with more dilute acid the coagulated 
proteid is much more quickly digested, but the reverse is true when acid 
of greater concentration is used. 

The comparative speed of peptic digestion of different kinds of pro- 
teid has, because of its practical bearing, been made the subject of much 
investigation.* 

Casein is the most easily digested of all forms of proteid. Fibrin is 
much more quickly digested than coagulated egg-white, though, according 
to its state of aggregation and time of boiling, the latter shows a con- 
siderable variation. In general, proteids of animal origin are more 
easily digested than those of vegetables, and of the latter legumin is 
most easily, glutin most difficultly, digestible® Jessen® observed that 
muscle fibre is more rapidly dissolved when raw than when coagulated 
by boiling or roasting, and that boiled milk is digested more slowly than 
unboiled. Beef appears to be both more easily dissolved and peptonised 
than fish.7 

The conclusion ought not, however, to be too hastily drawn that 
those forms of proteid which are most easily dissolved by gastric juice 
are therefore best and most nutritious; gastric juice is not the only 
proteolytic fluid which acts on the food. If the food has been properly 


1 Verhandl. d. naturh.-med. Ver. zu Heidelberg, 1876, N. F., Bd. i. S. 90. 

2 “*Vorlesungen,” Wien, 1887, Aufl. 4, Th. 1, S. 312. 

3 Jahresb. ti. d. Fortschr. d. Thier-Chem., Wiesbaden, 1873, Bd. iii. S. 175. 

4 Besides those quoted below, see Stutzer, Zéschr. f. physiol. Chem., Strassburg, 1885, 
Bd. ix. S. 212; 1886, Bd. x. S. 153; 1887, Bd. xi. S. 207; 1888, Bd. xii. S. 72; Pfeiffer, 
ibid., 1887, Bd. xi. S. 1; Wolff, Landwirthsch. Jahrb., 1890, Bd. xix. S. 795; Hahn, 
Virchow’s Archiv, 1894, Bd. exxxvii. S. 597. 

5 Maly, in Hermann’s ‘‘ Handbuch,” Bd. v. (2) S. 79. 

6 Ztschr. f. Biol., Miinchen, 1883, Bd. xix. S. 129. See also Bergeat, ibid., 1888, Bd. 
xxiv. S. 139. 

7 Chittenden and Cummins, 4m. Chem. Journ., Baltimore, 1884, vol. vi. No. 5; 
Popoff, Ztschr. f. physiol. Chem., Strassburg, 1890, Bd. xxiv. S. 524. 


334 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


masticated, it is not necessary that it should be dissolved before leaving 
the stomach. It does not follow that the foods which are more rapidly 
dissolved are also more rapidly peptonised, nor, indeed, that those which 
are more rapidly peptonised are also more thoroughly utilised by the 
organism.? 

Rennin.?—The presence of a milk-curdling principle in the stomach 
of the calf has been known for ages, but it is only within recent times 
that it has been shown that this action is due to the presence of a 
soluble ferment or enzyme. 

This enzyme is present in neutral aqueous infusions of the mucous 
membrane of the stomach of the calf and sheep, but in the case of other 
mammalia, of birds and of fishes, the zymogen is more stable, and the 
active enzyme itself is only set free on treating a neutral infusion with 
acid.? 

The presence of rennin in the stomachs of birds and fishes is very 
remarkable, and points to some wider function of the enzyme, at present 
unknown to us, since it cannot be supposed that in such animals the 
ferment plays any part in connection with the clotting of milk. Many 
plant juices also contain enzymes which coagulate milk, such as the latter 
of the fig treet and of Carica pepaya, and the flowers of many cynaria. 
Milk® is also coagulated by bacterial action with the development of 
an acid reaction due to lactic acid (in the souring of milk). A curdy 
precipitate somewhat resembling a clot is caused by the addition of acids 
to milk, which led to the erroneous analogy being drawn, that the 
coagulation of milk by rennet was also an acid action, due to lactic acid 
set free from the lactose of the milk by ferment action. 


The following is a summary of the proofs that milk coagulation is not an 
acid action, but due to a specific enzyme (rennin), which acts on a proteid 
(caseinogen) of the milk:—1. When a neutral solution of rennin (rennet) is 
added to alkaline milk, and the mixture is kept at 38°-40° C., complete 
coagulation occurs in 4-10 minutes, and in the process the reaction remains 
unchanged. 2. Solutions of caseinogen prepared from milk and free from 
lactose coagulate in presence of calcium salts, on the addition of rennin. 
3. Purified solutions of rennin have no action whatever on lactose.® 


Rennin is always present under normal conditions in human gastric 
juice, both at birth and in the adult.’ The distribution of the enzyme 
and its zymogen in the gastric mucous membrane is similar to that of 


1 See ‘‘ Absorption of Proteids,” p. 441. 

2 The name is due to Sheridan Lea ; that of chymosin has been proposed by Deschamp. 

3 Hammarsten, ‘‘ Lehrbuch d. physiol. Chem.,’’ Wiesbaden, 1895, Aufl. 3, S. 241. 

4This also contains a proteolytic ferment, active in either alkaline, neutral, or acid 
reaction (Baginsky, Ztschr. f. physiol. Chem., Strassburg, 1882, Bd. vii. S. 209 ; Arch. f. 
Anat. u. Physiol., Leipzig, 1883, S. 276). 

> For the chemistry of milk, see p. 125. 

6 These proofs are due to: Heintz, Journ. f. prakt. Chem., Leipzig, 1872, N. F., Bd. vi. 
S. 374 ; Hammarsten, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1872, Bd. ii. 
S. 118; 1874, Bd. iv. S. 135; 1887, Bd. vii. S. 158 ; ‘‘ Zur Kenntniss des Caseins und der 
Wirkung des Labfermentes,” Upsala, 1877; Al. Schmidt, Jahresb. ti. d. Fortschr. d. Thier- 
Chem., Wiesbaden, 1874, Bd. iv. 8. 154. From the fact that rennet when impure acts on 
lactose, but not after purification, Hammarsten supposed that gastric juice contained a 
third enzyme, which acted on lactose, forming lactic acid, but this has not been sub- 
stantiated. 

7 Zweifel, Centralbl. f. d. med. Wissensch., Berlin, 1874, Bd. xii. S. 939 ; Hammarsten, 
Beitr. z. Anat. u. Physiol. als Festyabe C. Ludwig, Leipzig, 1874; Schumberg, Virchow’s 
Archiv, 1884, Bd. xevii. S. 260; Boas, Centralbl. f. d. med. Wissensch., Berlin, 1887, Bd. 
xxv. §. 417. 


ome a 


SEPARATION OF PEPSIN AND RENNIN. 335 


pepsin; that is, the pyloric part furnishes very weak extracts compared 
with those yielded by the fundus.! 

Solutions of rennin, commonly called rennets, may be prepared by 
extracting the mucous membrane of the stomach in various ways, of 
which the followi ing is a Summary :— 


1. Extraction of the mucous membrane of the stomach of the calf for some 
days with glycerin. Purer solutions may be afterwards obtained by precipi- 
tating the glycerin extract with excess of alcohol, filtering, and treating the 
precipitate with water. 

2. Digesting the mucous membrane of the stomach for twenty-four hours 
at atmospheric temperature with water containing | to 2 parts per mille of 
hydrochloric acid, filtering, and neutralising. 

3. Extracting with a saturated aqueous solution of salicylic acid, precipi- 
tating by excess of alcohol, and extracting the precipitate with water. 

4, The best extractive for making permanent preparations is solution of 
sodium chloride of from 5 to 15 per cent. concentration, putrefaction being 
prevented by the addition of alcohol, thymol, or some such innocuous pre- 
servative. 


Effects of temperature.—Rennin is quickly destroyed in neutral solu- 
pap by a temperature of 70° C.,in acid solution by a temperature of 

3° C. The temperature of maximum activity lies at 38 to 40°C. It 
ah acts, though more slowly, at atmospheric temperatures. 

Action of acids and alkalics—Rennin is rapidly destroyed by caustic 
alkalies; even 0-025 per cent. of caustic soda suffices, at atmospheric 
temperature in twenty-four hours, to completely destroy a very active 
solution. The amount of ferment so destroyed varies as usual with the 
duration of the action, the temperature, and the concentration of the 
destructive agent. In their behaviour towards alkaline carbonates 
rennin and its zymogen closely resemble pepsin and pepsinogen; rennin 
being quickly destroy ed by 0°5 to 1:0 per cent. of sodium carbonate 
(Na, CO ,), While its zymogen is much less readily affected thereby.? 

Rennin is destroyed by standing under alcohol, but this change occurs 
more slowly than the corresponding one in the case of pepsin. 

Separation of pepsin and rennin.—For the preparation of a pepsin 
solution free from rennin, a gastric extract containing both enzymes is 
submitted to digestion in 0°3 per cent. hydrochloric acid for forty-eight 
hours at 38° to 40° C.; ; the rennin is completely destroyed. Hammarsten # 
utilises Briicke’s pr inciple of mechanical precipitation, for the preparation 
of a rennin solution free from pepsin, in the following method. An acid 
infusion of the gastric mucous membrane is neutralised with magnesium 
carbonate, and ‘enough neutral acetate of lead is added to completel ly 
precipitate all the pepsin accompanied by a portion of the rennin.t The 
filtrate is further precipitated by more lead acetate aided by ammonia, 
and the precipitate is separated and decomposed by very dilute sulphuric 
acid, so yielding a solution of rennin almost free from proteid. This 
solution is then further purified by mechanical precipitation with 
cholesterin. 

The final product so obtained produced no effect on a flock of fibrin 


1 Hammarsten, Joc. cit. 

* Langley, Journ. Physiol., Cambridge and London, 1880-2, vol. iii. p. 287; Boas, Ztschr. 
jf. klin. Med., Berlin, 1888, Bd. xiv. 8. 249. 

3 Loc. cit. 4 As tested by the inability of the filtrate to digest fibrin. 


336 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


in twenty-four hours, but caused coagulation of fresh milk of neutral 
reaction in one to three minutes. 

Such a solution of purified rennin behaves essentially differently in 
its reactions from a proteid solution. It is not coagulated by heat, 
does not give the xanthoproteic reaction, and is not precipitated by 
aleohol, tannin, iodine, or neutral acetate of lead; it is, however, pre- 
cipitated by basic acetate of lead. 


THE PANCREATIC ENZYMES. 


The pancreatic juice of all vertebrates in which it has been tested? 
contains three distinct enzymes, each of which acts on a different class 
of the three great divisions of foodstuffs? In the invertebrates generally, 
the place of the pancreas is taken by the so-called liver, hepato-pancreas, 
or digestive gland. This usually contains enzymes, capable collectively 
of attacking all three classes of foodstuffs, and with varying reaction ; 
so that this organ may be considered as taking the place of the combined 
digestive glands of the vertebrates.? 

The different enzymes of the pancreas do not appear equally early in 
life; the pancreatic diastase, amylopsin, is not found at birth, but first 
appears a month or more afterwards. The proteolytic ferment, trypsin, 
is found during the last third of fcetal life® No similar information is 
on record regarding the fat-splitting ferment, steapsin. 

The relative amounts of the different enzymes in pancreatic juice 
vary considerably. In passing from a flesh to a bread-and-milk diet, the 
proteolytic activity is said to diminish while the diastatic activity im- 
creases, and vice versd@ in passing from a carbohydrate to a proteid 
diet.® 

In addition to the methods of extraction already described under 
general methods, the pancreatic enzymes may be obtained in solution by 
various other methods, of which the following is a summary :— 


1. By extracting with water saturated with chloroform; such an extract 
keeps well and is very efficient.’ 

2. By extracting with water containing 3 to 4 per cent. of a mixture of 
2 parts of boracic acid and 1 part of borax.® 

3. By placing the fresh gland, finely minced, in a saturated solution of 
sodium chloride. This gives a strong solution of the proteolytic and diastatie 
enzymes.® 

4. By extracting the fresh pancreas, freed from fat and finely minced, 
with about four times its weight of 25 per cent. alcohol for four or five days ; 
succeeded by filtration, which may be assisted by a trace of acetic acid.!° 


1 For a detailed account of the action of pancreatic extracts in different animals, see 
Harris and Gow, Journ. Physiol., Cambridge and London, 1892, vol. xiii. p. 469. 

2 A milk curdling enzyme is also present ; see Milk, p. 127. 

3 Krukenberg, ‘‘Grundziige einer vergleichenden Physiologie der Verdauung,” Heidel- 
berg, 1882. 

4 Korowin, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 18738, Bd. iii; Zweifel, 
‘‘Untersuch. ueber den Verdauungsapparat der Neugeborenen,” Berlin, 1874. 

5 Albertoni, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1878, Bd. vill. S. 254. 

6 Vassiliew, Arch. de sc. biol., St. Pétersbourg, 1893, vol. ii. p. 219; Jahresb. tw. d. 
Fortschr. d. Thier-Chem., Wiesbaden, 1893, Bd. xxiii. S. 219. 

7 Roberts, ‘‘ Lumleian Lectures,” 1880 ; ‘‘ Digestion and Diet,” London, 1891, p. 18. 

8 Roberts, loc. cit. 

® Roberts, Zoc. cit. Also recommended by Harris and Gow, Journ. Physiol., Cambridge 
and London, 1892, vol. xiii. p. 469. 

10 Roberts, doc. cit. 


THE PANCREATIC ENZYMES. 337 


5. A very active proteolytic extract may be obtained by extracting with 
water containing 0°01 to 0°05 per cent. of ammonia. The filtered extract gives 
a precipitate with acetic acid which digests proteid very energetically, and can 
be further purified.! 

In preparing pancreatic extracts, it should be remembered that the 
gland does not at all periods contain the same amount of the ferments, 
or rather their zymogens, but that the amount fluctuates within wide 
limits according to the period after a meal. The pancreas of an animal 
in which digestion is not going on will yield little or no ferments; the 
best time is from four to seven hours after a meal. An inactive prepara- 
tion may often be cured by making the extract faintly acid with acetic 
acid some time before using; this sets free ferment which may be present 
as zymogen in the extract. 

Trypsin.2—The proteolytic enzyme of the pancreatic juice in the 
purest form in which Kiihne obtained it, gave all the proteid reactions, 
thus differing from all the other purer forms of enzyme hitherto described. 
Kiihne’s product is decomposed on boiling, yielding 20 per cent. of 
albumin and 80 per cent. of peptone; it is soluble in water, but insoluble 
in anhydrous alcohol or glycerin. The insolubility of the purified dry 
product in anhydrous glycerin accords with v. Wittich’s* observations, 
that both enzymes can be extracted from the fresh gland by glycerin ; 
but if the gland mass be previously thoroughly dried by extraction with 
alcohol, glycerin only takes out the diastatic enzyme, the proteolytic 
one being left behind. 

Influence of temperature—The activity of trypsin increases, accord- 
ing to Roberts,! with rising temperature until 60° C. is reached, and 
then rapidly falls, all action ceasing between 75° C. and 80° C.; 
Biernacki® states that purified trypsin in 0°25 to 0°5 per cent. sodium 
carbonate solution is destroyed in five minutes by a temperature of 
50° C.,and in neutral solution by a temperature of 45° C. The presence 
of albumoses or of certain ammonium salts protects against the action 
of elevated temperature in alkaline solution. 

Influence of reaction.—Kihne ® made the observation that the activity 
of trypsin was permanently destroyed by digesting its solutions with 
pepsin and hydrochloric acid, and attributed the greater share in this 
action to the pepsin. Boas’ afterwards showed that the destruction 
might be due to acid action alone, by demonstrating that addition of 
hydrochloric acid to the filtered intestinal contents causes a precipitate 
containing nearly all the ferments. This precipitate, on standing for a 
few hours under the acid, became inert, but, when quickly separated and 
redissolved in sodium carbonate, showed both diastatic and proteolytic 
action. The matter has recently been again tested by Melzer’ who 


1 Hammarsten, ‘‘ Lehrbuch,” Wiesbaden, 1895, Aufl. 3, S. 265. 

2So named by Kiihne, Verhandl. d. naturh.-med. Ver, zu Heidelberg, 1876, N. F., 
Bd. i. S. 190. Danilewski (Virchow’s Archiv, 1862, Bd. xxv. S. 279) had previously to this 
obtained a product which failed to give many of the usual proteid reactions. 

3 Arch. f. d. ges. Physiol., Bonn, 1869, Bd. ii. S. 198 ; Hiifner (Jahresb. ti. d. Fortschr. 
d. Thier-Chem., Wiesbaden, 1872, Bd. ii. S. 360) failed to obtain a similar result, probably 
through using glycerin containing water. 

4 Proc. Roy. Soc. London, 1881, vol. xxxii. p. 158. 

5 Zischr. f. Biol., Mimchen, 1891, Bd. xxviii. S. 51. 

6 Verhandl. d. naturh.-med. Ver. zu Heidelberg, 1876, N. F., Bd. i. S. 193. 

7 Ztschr. f. klin. Med., Berlin, 1890, Bd. xvii. S. 170. 

8 Inaug. Diss., Erlangen, 1894; Melzer’s figures show that most of the destruction is due 
to acid alone. 


VOL. I.—22 


338 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


finds that hydrochloric acid alone does destroy trypsin, but not so 
rapidly as when pepsin is also present. 

All possible opimions have been held by various observers as to the 
reaction with which trypsin acts, and acts best;! it is now generally 
accepted that it can act either in an alkaline, neutral, or very faintly 
acid solution, but that the optimum reaction is that given by about 1 
per cent. sodium carbonate (Na,Co,).? 

Active proteolysis by trypsin cannot take place in presence of an 
acid reaction, except the acid be combined with proteid. If the proteid 
be completely saturated with acid, the rate is greatly slackened even 
when there is no free acid in the solution; and if much proteid be 
present, the ferment action may be abolished even before this stage is 
reached.? 

Heidenhain * states that the concentration of sodium carbonate 
necessary to ensure maximum activity varies with the richness im 
ferment of the solution experimented upon; the richer in ferment, the 
lower the percentage of sodium carbonate necessary for maximum 
action. 

Other alkaline carbonates are much less effective than sodium 
carbonate in increasing the activity of trypsin. The action is also said 
to be assisted, but to a still less degree, by other salts of the alkalies.® 

Organic acids have not nearly so destructive an action as hydro- 
chloric acids, arsenious acid has no hindering effect, and salicylic acid 
only when in saturated solution.® 

The nature of the proteid submitted to digestion by trypsin has 
also a profound effect upon the rapidity of the process. Fresh unboiled 
fibrin is so quickly dissolved that it cannot be used as a comparative 
test for trypsin, and fibrin which has been boiled, or dises of hard-boiled 
white of egg, must be substituted for it. 

Amylopsin.—An active amylolytic extract of pancreas can best be 
prepared by following Roberts’ method of extracting with dilute alcohol. 

Pancreatic juice is much more intensely diastatic than saliva, but 
it cannot be determined, until some method for isolating the diastases 
has been discovered, whether this is due to a difference in the amylolytic 
ferments present or to a mere difference in concentration. It is certain, 
however, that salivary, pancreatic, and malt diastases are practically 
identical in the qualitative character of their action on starch. Roberts 


See Corvisart, ‘‘ Collection de mémoires sur une function peu connue du pancreas, la 
digestion des aliments azotés,” Paris, 1857-8, p. 41; Meissner, Ztschr. f. rat. Med., 1859, 
3 Reihe, Bd. vii. S. 17; Kithne, Verhandl. d. naturh.-med. Ver. zu Heidelberg, N. F., 
Bd. i. S. 190 ; Danilewski, Virchow’s Archiv, 1862, Bd. xxv. S. 291; May, Untersuch. a. d. 
physiol. Inst. d. Univ. Heidelberg, 1880, Bd. iii. S. 378 ; Lindberger, Jahresb. wi. d. Fortschr. 
d. Thier-Chem., Wiesbaden, 1883, Bd. xiii. S. 280; Ewald, Ztschr. f. klin. Med., Berlin, 
se ea i. S. 615 ; Langley, Journ. Physiol., Cambridge and London, 1880-2, vol. iii. 
p. 262. 

2 Weiss, Virchow’s Archiv, 1876, Bd. lxviii. S. 413 ; Melzer, Inaug. Diss., Erlangen, 
1894. According to the latter author, a digestion which is complete in two and a half 
hours with 1 per cent. Na,CO, is incomplete in twenty-four hours with either 3 per cent. 
Na,Co, or 0010 per cent. of HCl. 

* Chittenden and Cummins, Stud. Lab. Physiol. Chem., New Haven, 1885, vol. i. p. 100. 

4 Hermann’s ‘‘ Handbuch,” Bd. v. (1), S. 187. 

® Podolinski, ‘‘ Beitr. z. Kenntniss des pankreatische Eiweissfermentes,” Breslau, 1876, 
S. 43. See also Chittenden and Cummins, Zoc. cit., who found that borax and potassium 
cyanide augment, while salts of mercury and iron decrease, the activity. 

6 Lindberger, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1883, Bd. xiii. 
S. 280 ; Schafer u. Bohm, dbid., 1872, Bd. ii. S. 363; Kithne, Verhandl. d. naturh.-med. 
Ver. zu Heidelberg, N. F., Bd. i. S. 190. 


THE PANCREATIC ENZYMES. 339 


states that pancreatic diastase is capable of converting 40,000 times 
its weight of starch into maltose and dextrin; Kroger, that 1 grm. of 
pancreatic juice, containing 0°021 grm. of dry solid, of which in turn 
only a small fraction could be amylopsin, digested in half an hour 4°67 
erms. of starch. 

Influence of temperature—The rate of conversion increases with 
rising temperature from 0° C. to 30° C.; from 30° C. to 45° C. the rate 
is at a maximum and practically constant. Above 45° C. the action 
becomes slower with rising temperature, and ceases between 60° C. and 
70° C., the ferment being here destroyed.! 

Influence of reaction—Pancreatic diastase closely resembles salivary 
diastase in its behaviour to change in reaction of the medium in which 
it is dissolved. It seems to act best when neutralised or in presence 
of minute traces of acid; but a limit of acidity is soon reached beyond 
which the rapidity of action rapidly diminishes, and the enzyme itself 
is quickly destroyed.2. The optimum activity, according to Melzer’s 
measurements, coincides with the presence of 0-01 per cent. of hydro- 
chloric acid. 

Pialyn.—Very little is known of the fat-splitting enzyme, pialyn, of 
the pancreatic juice. That the action is due to an enzyme is shown 
by the following experimental observations:—(a) The action is de- 
stroyed when the pancreatic juice or active pancreatic extracts are 
boiled; (4) it takes place in presence of antiseptics, and hence cannot 
be due to bacteria.* 

The enzyme is much less stable than either of the other two 
associated with it in pancreatic juice. It is especially susceptible to 
the action of acids, being quickly destroyed by all except the higher 
fatty acids, so that great care to avoid acidity of solution must be 
exercised in the preparation of it from the pancreas. Paschutin + 
recommends for its extraction a dilute solution of sodium carbonate 
and bicarbonate in water, and Griitzner® that it should be extracted 
from the perfectly fresh pancreas with a solution containing 90 c.c. of 
glycerin to 10 cc. of 1 per cent. sodium carbonate, ten times the weight 
of gland to be extracted being taken of this fluid. However extracted, 
ut must be taken from a fresh gland and not from one which has stood over 
a day, as in the case of the other two enzymes, for thereby an acid reaction 
would be developed, and as a consequence the fat-splitting enzyme would 
be destroyed. 

The rapidity of action of the enzyme is at first creased by rising 
temperature. It acts almost twice as fast at 38° C. as at 18° C., but it 
is destroyed by boiling; the temperature of destruction is not accurately 
known. 

It acts more slowly in the presence of 0°25 per cent. of sodium 
carbonate than in neutral solution. 

Its activity is greatly increased by the presence of bile, still more 
by a mixture of bile and hydrochloric acid; this increase in activity is 
due to the bile salts or bile acids, which have a similar effect. The 
rapidity of action of the enzyme is usually much underrated, and it 

1 Roberts, ‘‘ Digestion and Diet,” London, 1891, p. 74; Proc. Roy. Soc. London, 1881, 
vol. xxxli. p. 145. 

2 Melzer, Inaug. Diss., Erlangen, 1894. 

* Nencki, Arch. f. exper. Path. u. Pharmakol., Leipzig, 1886, Bd. xx. 8. 367. 


4 Arch. f. Anat. u. Physiol., Leipzig, 1873, S. 386. 
> Arch. f. d. ges. Physiol., Bonn, 1876, Bd. xii. S. 302. 


340 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


is probable that it is capable of splitting up all the fat of a full meal 
in the ordinary time of digestion within the body.? 

Pialyn acts on other esters than the neutral fats causing a similar 
saponification.2 : 

Separation of the pancreatic enzymes.—There has, strictly speak- 
ing, been no complete isolation of the pancreatic enzymes obtained by 
the various workers on the subject. Partial success has been so far 
obtained, in that methods have been invented which yield solutions 
much richer in one of the two principal enzymes than in the other. 


Danilewski® was the first to tackle this difficult task, under the direction 
of Kithne. He found that, after shaking up a watery infusion of the 
pancreas of the dog with excess of magnesia, and filtering, there remained an 
infusion which possessed only a proteoly tic and diastatic action. 

This solution was mixed up with one quarter of its volume of thick colleen 
solution (in alcohol and ether), and thoroughly shaken. The collodion is 
thrown out of solution as a pasty mass, which mechanically carries with it 
the proteolytic ferment, while the diastatic ferment remains in solution. 
The collodion is removed, washed, and dissolved in a mixture of alcohol and 
ether. This solution is allowed to stand for some days, when the proteolytic 
ferment with a little proteid falls to the bottom as a yellow sediment. This 
sediment, when dissolved again in water, digests fibrin in alkaline or neutral, 
not in acid solution. The filtrate from the collodion, which contains the 
diastatie enzyme, is evaporated down in vacuo, and filtered from anything 
which precipitates out. The filtrate is precipitated by excess of absolute 
alcohol, extracted by a mixture of 2 parts water to 1 part alcohol, and 
dried iz vacuo. The solution so obtained rapidly converted starch into 
sugar, and only possessed a very feeble action on fibrin. Lossnitzer * has 
repeated these experiments, and only partially confirms them. Neither of 
the two products obtained by Danilewski gave the xanthoproteic, or Millon’s 
reactions. 

Cohnheim ® obtained the diastatic enzyme from an infusion of pancreas, by 
a method identical with that by which he obtained ptyalin.® This substance 
possessed no proteolytic action, did not give the proteid reactions, but acted 
very energetically on starch. 

v. Wittich 7 made use of the insolubility of trypsin in dry glycerin to 
obtain an extract rich in diastatic ferment and free from proteolytic action. 
The pancreas is dehydrated in strong alcohol, and further allowed to stand 
under absolute alcohol for some time ; the tissue is then dried and extracted 
with dry glycerin; the extract after filtration is precipitated by excess of 
alcohol, and the precipitate is again extracted with dry glycerin. In this 
manner v. Wittich obtained an extract which did not act on fibrin and had 
an intense action on starch. Hiifner got an extract, on repeating the process, 
which also contained trypsin ; but as Kiihne states that trypsin is not soluble 
in glycerin, Hiifner’s results may be due to water in the glycerin em- 
ployed. 

Paschutin® attempted to separate the pancreatic enzymes by using as 


1 All these observations on the rapidity of action of this enzyme, and its variations, 
have been made by Rachford, Journ. Physiol., Cambridge and London, 1891, vol. xii. 

. 12. 
* Berthelot, Ann. d. chim., Paris, 1854, tome xli. p. 272; Nencki, Arch. f. exper. Path. 


u. Pharmakol., Leipzig, 1886, Bd. xx. S. 367; Baas, Ztschr. f. physiol. Chem., Strassburg, 
1890, Bd. xiv. "g. 416. 


3 Virchow’s Archiv, 1862, Bd. xxv. S. 279. 

4 Arch. d. Heilk., Leipzig, 1864, Bd. v. S. 556. 

5 Virchow’s Archiv, 1863, Bd. xxviii. S. 241. § See p. 328. 
7 Arch. f. d. ges. Physiol., Bonn, 1869, Bd. ii. S. 198. 

8 Arch. f. Anat. u, Physiol., Leipzig, 1873, S. 382. 


THE INTESTINAL ENZYMES. 341 


extractives concentrated solutions of different salts. He found that some salt 
solutions extracted all three ferments, while others especially extracted one 
ferment accompanied by traces of the others. Thus sodium chloride, sodium 
sulphate, and potassium chlorate extracted all three ferments indifferently ; 
sodium bicarbonate, with a little of the normal carbonate added, extracted best 
the fat-splitting ferment; the proteolytic ferment was taken up best by 
potassium iodide, arsenite, or sulphite; and the diastatic ferment by 
potassium arsenate alone or with the addition of ammonia. 

Dastre! has recently described methods for approximately separating the 
proteolytic and diastatic enzymes of the pancreas. 

1. If the pancreas of an animal killed during digestion be cut into large 
pieces, and these then digested for 15-20 minutes at 40° C., in normal saline 
(‘7 per cent.), the filtrate is found to possess a strong diastatic action, but 
scarcely any proteolytic action. If, after this first extraction, the pieces are 
finely minced and extracted anew with normal saline (1 per cent. of sodium 
fluoride being added to prevent putrefaction), an extract is obtained rich 
in proteolytic ferment, but containing scarcely any diastase. 

2. On extracting a fresh gland with alcohol of increasing strength, after- 
wards with ether, and drying over sulphuric acid, a powder is obtained 
which yields, on extraction with saline, a fluid which is almost inert towards 
starch, but is actively proteolytic. 

3. An extract made from the pancreas of an animal which has not been fed 
for some days, contains proteolytic ferment but has scarcely any diastatic action. 


THE INTESTINAL ENZYMES. 


Practically nothing is known of the enzymes of the small intestine 
save their action on foodstuffs; none of them have been obtained in 
even approximately pure condition, and the fact that there are enzymes 
rests on the observations—(1) that the action is destroyed by boiling, 
and (2) that it takes place under antiseptic conditions. Until the 
importance of this latter condition was demonstrated by the work of 
Kiihne on pancreatic digestion, there was much difference of opinion 
as to whether the succus entericus contained a proteolytic enzyme 
or not; some observers had observed digestion of proteids by this 
fluid, and others had been unable to do so. At length it was shown 
by Masloff? and by Wenz? that when precautions are taken to 
prevent bacterial growth, the succus entericus or extracts of the 
intestinal mucous membranes have no action on proteids or on 
albumoses. 

With regard to the action of succus entericus on carbohydrates, the 
more recent work on the subject all goes to show that starch is con- 
verted into maltose, maltose into dextrose, and cane-sugar into dextrose 
and levulose, both by the succus entericus and by extracts of the 
intestinal mucous membrane. 

The succus entericus contains no enzyme which acts on neutral fats. 
The power of emulsifying fats, which was occasionally observed by the 
earlier workers on the subject, was doubtless due to the alkalinity of the 


1 Compt. rend. Soc. de biol., Paris, 1893, tome xly. p. 648; Arch. de physiol. norm. et path., 
Paris, 1893, tome xxv. p. 774. 

2 Untersuch. a. d. physiol. Inst. d. Univ. Heidelberg, 1882, Bd. ii. S. 920. Masloff 
found very slight action of the juice when acidified, probably due to infiltrated pepsin. 

3 Zischr. f. Biol., Miinchen, 1886, Bd. xxii. S. 1. This result is confirmed by the 
observations of Tubby and Manning on human succus entericus, Guy’s Hosp. Rep., London, 
1891, vol. xlviii. p. 277. 


342 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


fluid, aided by the presence of free fatty acid in the fat used for the 
experiments.? 

Paschutin? attempted by two different methods to separate the 
diastatic and inverting ferments :— 


1. An infusion of the intestinal mucous membrane was made by rubbing 
it up with water and powdered glass, and filtering. When this infusion was 
mixed with a solution of collodion, the precipitated collodion brought down 
most of the inverting enzyme, and most of the diastatic enzyme was left in 
solution, but only a partial separation could be effected in this manner. 

2. The mucous coat of a piece of intestine was freed from the other coats, 
and then water was filtered through this, under pressure. The fluid which 
filtered through acted energetically on starch, but had no action or only a 
very feeble one on cane-sugar. 


THE CHEMICAL COMPOSITION OF THE DIGESTIVE 
SECRETIONS. 


SALIVA. 


The saliva is a mixture in varying proportions of the secretions 
of the different salivary glands. As these secretions differ from 
one another considerably in chemical composition, it will be well 
to consider first the physical and chemical nature of each of them 
in turn, and afterwards that of the fluid which results from their 
admixture. 

Submaxillary saliva.—Submaxillary saliva may be obtained by in- 
serting a fine cannula into the opening of Wharton’s duct. In some 
individuals Wharton’s duct carries to the mouth the secretion of the 
submaxillary gland only, in others the duct of Bartholin leads into 
Wharton’s duct, when the latter conducts the mixed secretion of the 
submaxillary and sublingual glands to the mouth. The tongue should 
be raised, but not too high, the cannula carefully imserted and gently 
pushed into the duct for about an inch. By this procedure the end of 
the cannula is thrust past the opening of the duct of the sublingual 
gland, in case both glands share a common duct, and so the obtaining of 
submaxillary saliva only is ensured.* 

Human submaxillary saliva is a clear, watery, mobile fluid, which 
becomes viscid on standing in contact with air, and deposits floceuli. 
It is always alkaline in reaction. On boiling, it becomes cloudy, and 
the cloudiness is increased by the addition of acid. Its specific gravity 
varies between 1:0026 and 1:0033, and is lessened by hunger. The 
amount of total solids lies between 0°36 and 0-46 per cent., and is not 
much influenced by food. According to Eckhard, it contains no 
sulphoeyanates, while Oehl and Sertoli‘ state that it contains them, 
but in less amount than the secretion of the parotid. Colorimetric 

1 See, however, Schiff, Arch. de physiol. norm. et path., Paris, 1892, tome xxiv. p. 679. 
Schiff here repeats his earlier statements, that succus entericus acts both on proteids and 
neutral fats. Prege (Arch. f. d. ges. Physiol., Bonn, 1896, Bd. lxi. S. 359) has recently - 
obtained succus entericus from a Vella fistula in the sheep, and determined that it has no 
action on proteids or neutral fats. 

2 Arch. f. Anat. u. Physiol., Leipzig, 1871, S. 305. 

5 Eckhard, Jahresb. ii. d. Fortschr. d. ges. Med., Erlangen, 1862, Bd. i. S. 126; cited 
from Maly, Hermann’s ‘‘ Handbuch,” Bd. vy. (2), S. 17. 


4 Oehl, Jahresb. ii. d. Fortschr. d. ges. Med., Erlangen, 1865, Bd. i. S. 120; Sertoli, 
abid., 124. 


SUBLINGUAL SALIVA. 343 


measurements gave for the submaxillary saliva 0-004 per cent., for 
the parotid 0:03 per cent., of this substance, reckoned as potassium 
sulphocyanate. It contains ptyalin, as shown by its powerful diastatic 


action on starch. 


The submaxillary saliva in the dog contains much more mucin than in 
man, and is in consequence much more viscid. It is alkaline in reaction, 100 
germs. requiring for neutralisation 0°135 to 0°144 grms. of sulphuric acid, 
reckoned as SO,. On standing in contact with air, calcium carbonate is 
thrown down as a flocculent precipitate, which was previously held in solution 
by the dissolved carbon-dioxide as bicarbonate. The same result is brought 
about more rapidly by heating. It contains, at most, only traces of proteid 
or of sulphocyanate. Its specific gravity is 1:0026 to 1-004. 


The quantitative composition of the saliva obtained on stimulation of 
the submaxillary gland varies according to the nerve stimulated. The 
saliva obtained on stimulation of the sympathetic (sympathetic saliva) 
is scanty in quantity, and contains much mucin, which gives it a viscid 
consistency. Chorda saliva, on the other hand, is plentiful in quantity, 
contains less mucin, and is hence a thin watery fluid. The chorda saliva 
has a specific gravity of 1-:0049 to 1:0056, and contains 1:2 to 14 per 
cent. of total solids; sympathetic saliva has a specific gravity of 1:0075 
to 1:018, and contains 1:6 to 2°8 per cent. of total solids.t 

Parotid saliva.—Human parotid saliva may be obtained by intro- 
ducing a fine cannula into Stenson’s duct.? 

It is a thin, mobile fluid, usually clear, sometimes somewhat turbid, 
and contains no formed element save epithelial cells. It is alkaline in 
reaction, but the first few drops secreted may be neutral or acid, 
especially in a state of hunger; in all cases the alkalinity is less than 
that of submaxillary saliva.? Its specific gravity seems to be very 
variable (Mitscherlich, 1:006 to 1:008; Oehl, 1:010 to 1012 with scanty 
secretion, 1:0035 to 1:0039 with plentiful secretion; Hoppe-Seyler, 
1:0061 to 10088); the amount of total solids lies between 5 and 16 
parts per thousand. It contains traces of proteids, but is free from 
mucin; it also contains ptyalin and sulphocyanate. 

The parotid saliva of some animals, such as the dog and horse, is very 
rich in calcium bicarbonate, and often deposits crystals of calcium 
carbonate on standing.* Stimulation of Jacobson’s nerve in the dog 
produces a flow of saliva from the parotid, poor in organic constituents. 
If, before this is done, the cervical sympathetic be stimulated, which 
alone produces no effect, on now stimulating the nerve of Jacobson 
a flow of saliva is obtained which is much richer in organic con- 
stituents. 

Sublingual saliva. Oehl attempted to obtain human sublingual 
saliva by a similar method to that described in the case of the other two 
glands; he was only able to obtain a very small quantity, insufficient for 

1 Eckhard, Beitr. z. Anat. u. Physiol. (Eckhard), Giessen, 1860, Bd. ii. For further 
details regarding the influence of nerves on the composition of saliva, see article on 
-“* Mechanism of Salivary Secretion.” 

2 Eckhard, loc. cit.; Oehl, Jahresb. ii. d. Fortschr. d. ges. Med., Erlangen, 1865, Bd. i. 
S. 120. See also Brunton in Sanderson’s ‘‘ Handbook of the Physiol. Laboratory,” p. 467. 

8 See Astaschewsky, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1878, Bd. viii. 
S. 234; Fubini, dbid., S. 235. 

4 Lehmann, “Physiol. Chem.,” Bd. ii. S. 13. 


5 Heidenhain, Arch. f. d. ges. Physiol., Bonn, 1878, Bd. xvii. S. 28 ; also in Hermann’s 
‘* Handbuch,” Bd. v. (1), 8. 55. 


344 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


quantitative analysis, but made out that it was a clear slimy fluid of 
stronger alkaline reaction than submaxillary saliva, and containing 
mucin, diastatic ferment, and sulphocyanide. 


The sublingual saliva of the dog is a viscous, scarcely fluid mass ; it contains 
salivary corpuscles, but is otherwise quite clear and transparent, is alkaline in 
reaction, and contains 2°75 per cent. of total solids! Werther? has analysed 
the sublingual saliva of the dog, and finds that its great viscidity is not due 
to any excess of organic constituents ; he attributes it to the reaction which he 
found to be neutral or barely alkaline. The proportion of inorganic salts is 
much larger than in parotid or submaxillary saliva. 


Secretion of the mucous glands of the mouth.—This has not 
been obtained in man. In the dog it has been obtained by ligaturing 
the ducts of all the salivary glands, or by extirpating the salivary 
glands. The amount secreted is exceedingly small; it is a thick ropy 
mucus of alkaline reaction, full of fragments of epithelial and mucous 
cells, and containing about 1 per cent. of total solids. 

The mixed saliva.—Mixed saliva may easily be obtained from the 
mouth by depressing the head and everting the lower lip; or by 
depressing the head, keeping the mouth widely open, and avoiding 
all attempts to swallow. It is a clear, viscid, and very slightly 
opalescent fluid, which froths easily. It is normally alkaline in 
reaction; when it is acid this reaction is commonly due to fer- 
mentation of particles of food in the mouth. The alkalinity is least 
when fasting, as in the morning before breakfast, and reaches its 
maximum with the height of secretion during, or immediately after 
eating. According to Chittenden and Ely,* the alkalinity is equiva- 
lent to that of a solution containing 0°08 per cent. of sodium carbonate 
(Na,Cos). 

The quantitative composition of mixed saliva is very variable, as 
might be expected from the difference in composition of the secretions 
which form it, and the varying proportion in which these must be pre- 
sent in different samples. The amount of total solids in human saliva 
varies normally between 5 and 10 parts per 1000; the specific gravity 
between 1:002 and 1:008. 

Organic constituents—The organic matter is partially in suspension, 
and partially in solution. The suspended matter consists of squamous 
cells detached from the epithelium of the mouth, and of the sal- 
vary corpuscles, which are leucocytes altered by the action of the 
saliva, and containing granules which exhibit in fresh saliva active 
Brownian movements. The dissolved organic matter consists of 
mucin, ptyalin, and traces of proteids; the amount of the latter is 
so small that it cannot be quantitatively estimated. Saliva is also 
said to contain normally minute traces of urea; but the amount 
is so small that such a statement cannot be made with certainty. 
In pathological conditions the amount of urea present may, however, 
become very appreciable. Leucine and lactic acid are found under 


? Heidenhain, Stud. d. physiol. Inst. zu Breslau, Leipzig, Heft 4. 
2 Arch. f. d. ges. Physiol., Bonn, 1886, Bd. xxxviii. S. 2938. See also Langley and 
Fletcher, Phil. Trans., London, 1887, vol. clxxx, p. 109. 
3 Bidder and Schmidt, ‘ Die Ver danungssiifte, ” Mitau und Leipzig, 1852, S. 5. 
4 Am. Chem. Journ., Baltimore, 1883, p. 329. See also Werther, Arch. f. d. ges. Physiol., 
Bonn, 1886, Bd. xxxviii. S. 298. 


SULPHOC VANATE OF SALIVA. 345 


pathological conditions, but are not normal constituents. Grape-sugar 
and bile pigments are never found even in the severest cases of diabetes 
or icterus.? 

Inorganic constituents.—These consist of salts of the alkalies (chiefly 
sodium) and alkaline earths; principally as chlorides, but also as 
phosphates and carbonates. Calcium carbonate often separates from 
saliva, as a thin surface film, or as a cloudiness in the fluid on standing; 
this is due to the escape of carbon-dioxide by which the calcium was 
held in solution as bicarbonate. A precipitation of the calcium of the 
saliva, partially as carbonate and partially as phosphate, in the ducts of 
the salivary glands, often gives rise to salivary concretions; and a similar 
deposit, mixed with phosphate and traces of silica, forms the tartar 
of teeth. 

Sulphocyanate of saliva.—Treviranus,? as early as 1814, observed 
that when a dilute solution of ferric chloride is added to saliva a reddish 
coloration is obtained. This was even before sulphocyanic acid was 
known chemically, and Tiedemann and Gmelin? afterwards proved that 
the effect was due to the presence of a sulphocyanate. 


The amount of sulphocyanate is not large. Oehl states it as equivalent to 
0-00016-0:0084 per cent., estimated as potassium sulphocyanate, and Munk 
as equivalent to 0°01 per cent. sulphocyanic acid, or 0°014 per cent. of 
sodium sulphocyanate.® The presence of a sulphocyanate in saliva may be 
demonstrated qualitatively in several ways—(1) A very greatly diluted and 
slightly acidulated solution of ferric chloride is added drop by drop to saliva, 
when a reddish coloration is obtained, if sulphocyanate is present in normal 
quantity ; the colour disappears on adding mercuric chloride. This test is 
difficult to obtain. (2) A filter paper is dipped in a weak: solution of ferric 
chloride, containing a trace of hydrochloric acid, and then allowed to dry, when 
it should have only a faint amber colour. On such test paper a drop of saliva 
produces a reddish stain.®© (3) Filter paper is impregnated with tincture of 
guaiacum, and then drawn through a solution of 0°05 per cent. copper sulphate. 
On such paper, saliva containing sulphocyanate causes a blue stain.’ (4) Saliva 
is treated with iodic acid, when iodine is set free; this in turn is treated with 
starch paste, when the blue compound of starch and iodine appears. ‘This is 
said to be an exceedingly delicate reaction, showing a most minute trace of 
sulphocyanate, and not being produced by saliva free from sulphocyanate,® but 
iodic acid is an exceedingly unstable compound, and the latter statement is 
questionable. 

Sulphocyanate is often absent in human saliva. Some authors state that 
it is found in dog’s saliva, others that it is not; the explanation may be that 
its presence in dog’s saliva is also not constant. It is said to be absent in the 
saliva of the horse, ox, sheep, goat, and pig.® Leared !° found that sulpho- 


1See Maly, Hermann’s ‘‘ Handbuch,” Bd. vy. (2), S. 8. e 

2 The older analysts were accustomed to proportion the bases and acids, on the 
supposition that as much as possible of the so-called strongest acid was combined with the 
strongest base. We now know that the acids and bases are distributed according to definite 
laws, and no longer speak of so much chloride, for example, as existing in a complex 
mixture, but state separately so much sodium and so much chlorine, ete. 

3 « Biologie,” 1814, Bd. iv. S. 330. 

4 <<T)ie Verdauung nach Versuchen,”’ Bd. i. S. 8. 

5 See Maly, Hermann’s ‘‘ Handbuch,” Bd. vy. (2), S. 10, 14. 

6 Gscheidlen, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden,, 1874, Bd. iv. S. 91. 

’ Bottger, zbid., 1872, Bd. ii. S. 204. 

§ Solera, zb¢d., 1877, Bd. vii. S. 256; 1878, Bd. viii. S. 235. 

9 Ellenberger and Hofmeister, ‘‘ Vergleich. Phys. d. Haustiere,” Berlin, 1890, S. 
495. 

0 Proc. Roy. Soc. London, 1870, vol. xviii. p. 16. 


346 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


cyanate was present in the blood and urine as well as in the saliva. 
Gscheidlen! and Munk? have also found it in urine. 

An exalted importance has been given to the sulphocyanate in saliva, 
from its supposed origin from proteid, and from its assumed value as an 
indicator of the rate of proteid metabolism. Sulphocyanic acid has a 
similar constitution to cyanic acid, an atom of sulphur merely replacing an 
atom of oxygen, and the ammonium salt of sulphocyanic acid undergoes a 
similar decomposition to that of cyanic acid, yielding sulpho-urea instead 
of urea, thus :— 


Oxygen compounds—CN.OH; CN.O.NH,; CO.(NH,), 


(eyanic acid) (ammonium (urea) 
cyanate) 


Sulphur compounds—CN.SH; CN.S.NH,; CS.(NH,), 


(sulphocyanic (ammonium — (sulpho-urea) 
acid) sulphocyanate) 


From this relationship, from the presence of sulphur in its molecule, and 
from its presence in the urine, and in traces in the blood, it is probable that 
the sulphocyanate of the saliva is a product of proteid metabolism. Fenwick # 
has investigated the variation in the sulphocyanate of the saliva, especially in 
relation to the variations in the nutrition of the body under pathological 
conditions. He states that the amount of sulphocyanate bears a relationship 
to the amount of sulphur (as taurocholates) in the bile, and that when the 
bile is diverted from the alimentary canal the sulphocyanate of the saliva 
disappears. That it would be dangerous to take the amount of sulphocyanate 
as any gauge of the amount of proteid metabolism, is shown by its complete 
absence in many species of animals, and in many individuals where it is 
normally present in a species; this does not make any the less probable 
the statement that in those individuals in which sulphocyanate is present its 
quantity should vary with the activity of proteid metabolism. 

Saliva also contains traces of nitrites! which may be demonstrated by 
diluting saliva with five times its volume of water, making acid with sul- 
phuric acid and adding a solution of metadiamido-benzol, when an intense 
yellow colour is produced. In this way Griess estimated colorimetrically 
the amount of nitrite in saliva at 1-10 mgrms. per litre. Minute traces of 
ammonia may also be shown to be present in saliva by the addition of Nessler’s 
reagent.® 

Gases of the salivan—The saliva holds considerable volumes of gas in 
solution or in chemical combination. In human parotid saliva, Kiilz® found 
in 100 vols. of saliva, of oxygen, 1:46 vols.; of nitrogen, 2°8 vols. ; and of 
carbon-dioxide 66°7 vols., of which latter 62 vols. were in chemical 
combination. In submaxillary saliva of the dog, obtained by stimulating 
the chorda tympani, Pfliiger™ found 0°5-0°8 vols. of oxygen, 0°9-1:0 vols. 
of nitrogen, and 64°73-85:13 vols. of carbon-dioxide, most of the latter 
being chemically combined. These figures are interesting, both because of the 
large amount of carbon-dioxide present, and the fact that the oxygen exceeds 
the amount dissolved by blood plasma. 


1 Arch. f. d. ges. Physiol., Bonn, 1877, Bd. xiv. S. 401. 

2 Virchow’s Archiv, 1877, Bd. xix. S. 354. 

° Fenwick, ‘‘ The Saliva as a Test for Functional Disorders of the Liver,” London, 1889. 

4 Schonbein, Journ. f. prakt. Chem., Leipzig, Bd. lxxxvi. 8. 151; Schaer, Ztschr. f. Biol., 
Miinchen, Bd. vi. S. 467 ; Griess, Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. ii. S. 624. 

®> Maly, Hermann’s ‘‘ Handbuch,” Bd. vy. (2), S. 8. See also W. Sticker, Aiinchen. 
med. Wehnsehr., 1896, Bd. xliii. Nos. 42-43. 

§ Zischr. f. Biol., Miinchen, 1887, Bd. xxiii. S. 321. 

7 Arch. f. d. ges. Physiol., Bonn, 1868, Bd. i. S. 686. 


ANALYSES OF SALIVA. 347 


Tables of Analyses of Saliva. 
TABLE I. 
SUBMAXILLARY SALIVA. 


GASES. 


| x If; | /Eie IV. Asu oF No. III. 


Water . . | 99145 | 996-04) 994°4 | 991°14]K,SO,  0°209 | =| CO, free19°3| 22°5 


=| CO, com- 

Total Solids 8°55| 3°96] 5°6 8°86 | KCl 0°940 | Z| bined 29°9| 42°5 
(a) Organic . 2°89} 1°51) 1°75| 3°53) Na Cl 1546 }2\ Nitrogen 0°7| 0°8 
(6) Inorganic 5°66| 2:45| 3°85| 5°33|Na,CO, 0°902 | 8! a s 

1. Soluble 4°50 3°59 | 5°27} CaCO, 0150 | 2!Oxygen 0°4| 0°6 
2. Insoluble 1°16 0:26| 0°06 | Ca,(PO,), 0°113 | é| 


| nae | 

Analyses I. and IT. are of dog’s saliva, by Bidder and Schmidt.1_ Analysis 
III. is by Herter.2 Analysis IV. is of cow’s saliva.? The ash analysis is by 
Herter. The gas analyses are of dog’s saliva by Pfltiger.° 


TABLE II. 
PAROTID SALIVA. 


1. IL. I. IV Void. ee ME VII 
} 

Water F . | 985°4-983°7 | 993-16 | 995-3 | 991°5-993°8 | 990°00 | 990°7 869°0 
Total Solids 14°6-16°3 6°84 4°7| 8:47-6:71 | 10°0 9°3 11:0 
(a) Organic . 9°0 3°44 1:4 153 | 2°06-6°0) 0°44 1:0 
(6) Inorganic . 5°3 3°40 3°3 6°93 4°8-8°73 | 8°82 10°0 
1. Soluble Py 2°1 6°25 eek BeFoN Ot FOG 

2. Insoluble 1 0°68 0°10 | Traces 


This table has been compiled from Maly.® I. and II. are analyses of 
human parotid saliva, by Mitscherlich and Hoppe-Seyler respectively. The 
former states the amount of the sulphocyanate in his sample at 0°3 per thousand. 
III. and IV. are of dog’s parotid saliva, by Jacubowitsch and Herter respect- 
ively ; that given as soluble is set down by them as CaCO,.  V. is of horse’s 
parotid saliva by Lehmann. VI. and VII. of the cow’s and ram’s parotid saliva 
respectively, by Lassaigne. 

TABLE III. 


SUBMAXILLARY, PAROTID, AND SUBLINGUAL SALIVA. 


Submaxillary Saliva. Parotid Saliva. Sublingual Saliva. 
1b Il. | Ill. BY. I. Il. Ill. I. Il. | Il. IV 
Water . 5 . |987°7 |988:7 | 983-2 |987:4 |991-4 |992°6 |992°6 |978°8 |984-7 |986°3 | 957-2 
Total Solids eres. il -s: ) 16 ser eka 86 (xaos |p 21:2) || tesa | tos7 | 12:8 
(a) Organic x3 66 | 10-2 6:2 he 0-6 4:0 Bee is, 4:3 a4 
(6) Inorganic . se 4°7 6°6 64 wae 6°8 4-1 4 13°4 9:4 9-4 
1. Soluble. 56 4:3 58 6:0 56 64 | So Oe alco! | 21257 9-0 9°3 
2. Insoluble . ; 0;42)|, (0°73))) 0-42): O45 ie 0°54}... 22. 0°68) 0-44) 0-17) 
Alkalinity— 
(as Na,CO,) . 1°6 1S fl een EO 1ics) te 7 ey 
Chlorides—- | 
(as NaCl) : SDD) eso B29 2°39 0°78 | 0°85} 7:06) 10°8 | 8:14 
| 1 t 


1 Maly, Hermann’s ‘‘ Handbuch,” Bd. vy. (2), S. 19. 

2 Hoppe-Seyler, ‘‘ Physiol. Chem.,” Bd. ii. S. 191. 

3 Lassaigne, cited by Maly, Joc. cit. 4 Loc. cit. 5 Maly, loc. cit. 

6 Hermann’s ‘‘ Handbuch,” Bd. v. (2), S. 16, 17; Hoppe-Seyler, ‘‘ Physiol. Chem.,” 
Bd. ii. S. 198, 199. 


348 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


This table shows the results obtained by Werther ! in four experiments on 
dogs, in which all three kinds of saliva were collected and analysed. The results 
have been placed in a similar form to that of the other tables, for ease of com- 
parison. It should be observed that the sublingual saliva was barely alkaline 
in all four experiments, while the submaxillary saliva was only so in one 
experiment; that the sublingual saliva contains in spite of its viscidity no 
more organic matter than the others, while it does contain much more 
chlorides. Human sublingual saliva has never been obtained in sufficient 
quantity for analysis. 


TABLE IY. 
BuccanL Mucus. 

Water . 3 : : : ; : : : ; : 990°02 
Total solids . ; ; . : : é : : : 9°98 

Organic matter— 
(a) Soluble in aleohol : : : : : : 1°67 
(6) Insoluble in alcohol . : : 5 : é ; 2°18 

Inorganic salts— 
Chiefly chloride and phosphate of sodium 5 : : 613 


From Bidder and Schmidt, quoted by Maly.? 


TABLE V. 
MIXED SALIVA. 
I. II. Ill. Te We VI. VII. 
Water : ; : ; . | 992°9 | 995-1 | 994-1 | 988°3| 994-7 | 994:2 | 989°6 
Total solids : ; (ul 4°84/ 5:9 VUE |) BSS 5°8 10°3 
| Suspended solids (epithe- 
| lium, mucus, ete.) . : 1°4 1°62 2°13 2°2. ae 
| Soluble organic matter. 3°8| 1°34] 1°42 3°27 1°4 3°58 
Potassium sulphocyanide . |... 0:06; 0°10 ac 0-04 BS 
Inorganic salts . ‘ : 1-9), 1582 iy, eee 1:08 | 522 6°79 


ASH OF MIrxED SALIVA. 


Human. Dog. 
| Total solids (in 1000 = 
of saliva) ; 1°82 6°79 
Phosphoric acid 0°51) . 
Soda 0°43 f desl 
Lime . 0°03 : 
| Magnesia non wh 
Alkaline chlorides 0°84 5°82 
| 


Analyses I. to VI. are of human saliva by Berzelius, Jacubowitsch, Frerichs, 
Tiedemann and Gmelin, Herter, and ammeriatnee respectively. Analysis 
VII. is of dog’s saliva by Schmidt. The table is taken from Maly,* except 
Analysis ite which is from Hammerbacher.t The analyses of ash are by 
Jacubowitsch.? In 1000 parts of the ash of mixed human saliva, Hammer- 
bacher® found 457-2 of K,O, 95-9 of Na,O, 50°11 of Fe,O,, 1°55 of MgO, 
63°8 of SO., 188-48 of P. [On and 183°5 of chlorine. 


* Arch. J. d. ges. Physiol., Bonn, 1886, Bd. xxxviii. S. 293. 

2 Hermann’s “Handbuch, SAB Gsvei(2)sSe 20 3 Tbid. Bd. v. (2), S. 14. 
4 Zischr. f. physiol. Chem. , Strassburg, Bd. y. 

> Maly, Joc. cit. 8 Loc. cit. 


GASTRIC fEICE, ; 349 


GASTRIC JUICE. 


Human gastric juice mixed with water or food may be obtained 
for clinical purposes by the use of a gastric sound or the stomach pump, 
but pure gastric juice cannot be obtained in this way, because when the 
stomach is empty the secretion of gastric juice stops, and can only 
be initiated by the drinking of water or the taking of food. 

Notwithstanding the considerable number of cases of gastric fistula 
in man already enumerated, the details as to the quantitative chemical 
composition and physical characteristics of that fluid are very meagre. 
Only one set of complete analyses of the fluid has been carried out by 
Schmidt, and these, along with certain incomplete analyses by other 
observers of the total solids and amount of acid, are all the quantitative 
data we possess. 

In a case of human gastric fistula, observed by C. Schmidt,? 
the fluid obtained was clear as water, less acid than dog’s gastric juice, 
and had a specific gravity of 1:0022-1:0024. It scarcely became clouded 
on heating, and left on evaporation a brownish-yellow deliquescent acid 
residue, which on incinerating left a colourless, neutral, or faintly alkaline 
ash, containing no carbonates. On distilling the liquid, only water 
came over, until the fluid attained the consistency of oil, then traces of 
hydrochloric acid, which became stronger as the process was continued. 

In a case observed by Richet, in which the csophagus had been 
oceluded by strong alkali, and the gastric fistula was the result of an 
operation, the gastric juice was also colourless, had a faint smell, and 
varied greatly in acidity. 

Pure gastric juice has also recently been obtained by Fremont * from 
a fistula in the isolated stomach of the dog. Gastric juice so obtained 
is a limpid, clear, colourless, inodorous, very acid, and powerfully peptic 
fluid, capable of digesting its own weight of coagulated albumin. The 
dog in question weighed 12 kilos., and yielded 800 grms. of gastric 
juice daily. If the secretion takes place at the same rate in the human 
subject, a man weighing 60 kilos. (132 lbs.) should secrete 4 litres 
of gastric juice daily. 

Pure gastric juice may be collected from a Pawlow fistula * twelve to 
fifteen hours after a true meal, by giving the animal a fictitious meal. 
The food which is eaten does not reach the stomach, but drops from 
an cesophageal fistula. The process of feeding induces reflexly an 
abundant secretion of gastric juice, which can be collected in a pure 
condition. A dog will go on feeding voraciously in this manner for 
hours, and in the course of an hour 200-300 c.c. of gastric juice may be 
collected. The animal is said to be unaffected in health by a collection 
of an hour per diem. 


1 This method is of more service clinically than physiologically as a mode of obtaining 
gastric juice in cases of dyspepsia, in order to determine the amount of acidity, and whether 
this is due to a normal amount of hydrochloric acid or to excess of organic acids, the pro- 
duct of bacterial action. See Leube, Sitzwngsb. d. phys.-med. Soc. zu Erlangen, 1871. 
Heft 3; Kiilz, Deutsche Ztschr. f. prakt. Med., Leipzig, 1875, No. 27; C. A. Ewald, 
‘Klinik der Verdauungskrankheiten,” 1890, Bd. i. S. 87; Gamgee, ‘‘ Physiological 
Chemistry,” vol. ii. pp. 163-178. 

2 The case was that of a healthy woman with a chronic fistula, yielding gastric juice 
freely without apparent effect on the health of the patient. 

3 Demonstrated by Herzen, International Congress, Bern, 1895. 

4 Pawlow and Schoumow-Simanowsky, Centralbl. f. Physiol., Leipzig u. Wien, 1889, 
Bd. iii. S. 113. See article on ‘‘ Mechanism of Gastric Secretion.” 


350 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


Konowaloff ! collected over 10 litres, as above described, and sub- 
jected the fluid to chemical examination. It was a clear, colourless, 
odourless fluid, which could be kept indefinitely without undergoing 
decomposition. When diluted with its own volume of water, it becomes 
somewhat cloudy ; with four volumes of water, a permanent opalescence 
resulted, which on further dilution eventually disappeared. On neutral- 
ising with alkali, a flocky precipitate appeared, redissolving in the shghtest 
excess. Cooling the juice to 10—-11° C. caused a finely granular precipit- 
ate to appear, which dissolved again on warming. Its specific gravity 
averaged 1:00478: total solids, 0-478 per cent.; acidity, equivalent to 
0:544 per cent. of hydrochloric acid. When the acid gastric juice is so 
removed the reaction of the urine becomes alkaline? (0°96-1°31 per cent. 
of Na,O). 

Freshly secreted gastric juice is said to contain traces of proteid,* 
which, on standing, is converted into albumoses and peptones; these, with 
traces of mucin, and the two enzymes, pepsin and rennin, are the only 
organic constituents. 

The inorganic salts consist chiefly of chlorides (with traces of phos- 
phates) of sodium, potassium, and calcium, and traces of magnesium 
and iron. 

The total amount of solids in gastric juice is very small, seldom 
amounting to more than 2 per cent., and often beg much less. Excess 
of alcohol causes a flocky precipitate containing all the organic matter. 

Alkalies and alkaline carbonates added to gastric juice cause a 
cloudiness or a flocky precipitate of tricalcic phosphate, with traces 
of phosphates of iron and magnesium, and some organic matter. The 
precipitation of tricalcic phosphate by ammonia shows that calcium is 
present as acid phosphate in gastric juice. 


Quantitative Conposition of Gastrie Juice. 


ib Il. Ill. ave 

Human. Dog. Dog. Sheep. 
Water. é ; é ; 994-40 973°06 97117 986-14 
Total solids 5°60 26°94 28°83 13°86 
Organic matter 3°19 17°13 17°34 4°05 
HCl 0°20? 3°34 2°34 1:23 
CaCl, 0°06 0°26 1°66 O11 
NaCl 1°46 2°50 3°15 4°37 
KCl 0°55 ue?) 1:07 1°52 
NH,Cl : : ‘ : : 0°47 0°54 0°47 
Ca,(PO,)z) - 3 3 : | { 173 2°29 1°18 
Mg,(PO,). - : : sje Osles 0°23 0°32 0°57 
Rene ee ON OR i ily | 0:08 0-12 0°33 

{ 


The analyses are by C. Schmidt, quoted from Maly, Hermann’s ‘‘ Handbuch,” Bd. y. (2) 
S. 70; Ann. d. Chem., Leipzig, 1854, Bd. xcii. S. 42; and ‘“‘ Verdauungssafte,” S. 44. 


Analysis I. is of human gastric juice, obtained from Schmidt’s case of 
gastric fistula already quoted ; it is evident that this gastric juice contained 


1 Tnaug. Diss., St. Petersburg, 1893; Jahresh. ti. d. Fortschr. d. Thier-Chem., Wies- 
baden, 1893, Bd. xxiii. 8. 289. 

* Schoumow-Simanowsky, Arch. de sc. biol., St. Pétersbourg, 1893, vol. ii. p. 462. 

3 Hammarsten, ‘‘ Lehrbuch der physiol. Chem.,” Wiesbaden, 1895, Aufl. 3, S. 233. 


THE ACID OF THE GASTRIC JUICE. 351 
much saliva, as the total solids and amount of acid are much less than those 
usually found. Analyses II. and III. are of dog’s saliva. Analysis II. gives 
the mean of ten determinations, in the case of a dog in which all the salivary 
ducts had been ligatured. Analysis III. gives the mean of three, in the case of 
a dog with normal salivary glands. Analysis IV. is that of the gastric juice 
of a sheep. 


The acid of the gastric juice.—The acid of the gastric juice 
has probably given rise to more discussion than any other subject in 
physiological chemistry. The principal points for consideration are— 
(a) the nature of the acid; (6) the seat of formation and the mode of 
origin of the acid; (¢) the function of the acid. 

The nature of the acid—Before discussing this question in detail, 
it may be well to state clearly the present state of opimion on the 
subject. 

It has been demonstrated that hydrochloric acid is the principal acid 
of the gastric juice, and that in the purer samples free from food it is 
always present, and is almost exclusively the only acid present; while in 
gastric Juice mixed with food, especially with carbohydrate food, it may 
be, and often undoubtedly is, accompanied by lactic acid. C. Schmidt, 
from a large number of painstaking and laborious analyses, concluded 
that the pure gastric juice of carnivora, obtained after a fast of eighteen 
to twenty hours, contains only hydrochloric acid, and no trace of lactic or 
acetic acids ; while the gastric juice of herbivora contains, besides hydro- 
chloric acid, small quantities of lactic acid, but this is even then probably 
from remnants of carbohydrate food.t 

Prout,? in 1824, first showed that gastric juice contains free hydro- 
chloric acid by the following method :— 

The contents of a stomach were mixed up with water, and, after the 
mixture had settled, the clear part was removed by decantation. This 
was divided into three equai portions, a, b, and e. 

(a) The first portion was evaporated to dryness, incinerated, and the 
total amount of chlorine in the ash determined by weighing, as silver 
chloride. 

(6) The second portion was first made alkaline by the addition of 
potash, then evaporated to dryness, incinerated, and the total chlorine 
determined as before. 

(c) In the third portion, the total acidity was determined by titration 
against standard alkali, and reckoned as hydrochloric acid. 

In portion (a) all the free acid is driven off as well as any which may 
be combined with volatile or decomposable bases (such as ammonium 
chloride); in portion (0) all the chlorine remains, that which was either 
free or combined with ammonia becoming converted into non-volatile 
potassium chloride; therefore the difference of (b) and (a) gives the free 
hydrochloric acid, plus any volatile chlorides which may be present. In 
(c) all the acid is estimated as hydrochloric acid, and by subtracting 
this from the difference of (>) and (a) the amount present as volatile 
chlorides is obtained. 

Prout also showed that when gastric juice is distilled, towards the 


1The stomach of the herbivora retains food for a much longer period than that of 
carnivora. Traces of food are usually found in the stomach of the sheep even thirty-six 
hours after a meal. See Cl. Bernard, ‘‘Legons de physiol. expér.” 1856, tome il. p. 
389. 

2 Phil, Trans., London, 1824, parti. p. 45. 


352 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


end of the process hydrochloric acid passes over. In addition, he tried 
to obtain lactic acid from gastric juice, but with negative results. 

The remarkable results so obtained by Prout were confirmed by 
Children! in England, by Braconnot? in France, and by Dunglison 
and Emmet,? with gastric juice obtained from Beaumont’s case of 
fistula. 

When the period at which they were carried out is considered, it 
must be admitted that these experiments of Prout were most ingenious, 
and he well deserves the honour of being the first to awaken the minds 
of men to the conception that the animal organism was capable of 
producing such a substance as hydrochloric acid. Physiological chemists, 
however, were chary in believing that the gentler forces of the animal 
organism were capable of producing such a substance as hydrochloric 
acid, which they were unable to obtain experimentally except by the 
use of potent inorganic reagents. Accordingly, objections flowed in 
against Prout’s work. 

Claude Bernard and Barreswil® showed that when sodium chloride 
was added to a solution of lactic acid, and the mixture distilled, hydro- 
chlorie acid appeared in the distillate towards the end of the process 
when the mixture was beginning to grow solid. They concluded that the 
free acid of the gastric juice was lactic acid. Lehmann® ascribed the 
free hydrochloric acid of Prout’s distillation experiment to the action of 
the lactic acid, concentrated by evaporation, on the calcium chloride also 
present in gastric juice. Many other observers were also agreed that 
the free acid in gastric juice was lactic acid.’ Blondlot® about this time 
enunciated the hypothesis that the acidity of the gastric juice was due 
in part to acid calcium phosphate, and evolved a theory, closely 
resembling a much more recent one by Maly, as to the origin of the 
acid by the formation of this substance, accompanied by traces of hydro- 
chlorie and phosphoric acids in the stomach wall, from the sodium 
chloride and calcium phosphate of the blood.® In presence of hydro- 
chloric acid it is now known that part of any calcium phosphate present 
would be resolved into acid phosphates, but the amount of calcium 
phosphate present in gastric juice is altogether insufficient to account for 
any appreciable part of its acidity. 

While the subject was still in this vexed condition, Bidder and 
Schmidt’s !° classical work on digestion appeared, containing the results 
of Schmidt’s experiments, to which reference has already been made. As 


1 Annals of Philosophy, July 1824. 

2 Ann. de chim., Paris, 1835, tome lix. p. 348. 

3 Published with Beaumont’s results, 1834. 

4 As is often the case in great discoveries, Prout seems not to have been much in time 
ahead of his fellows. Tiedemann and Gmelin state in the preface to their classical work, 
‘‘Die Verdauung nach Versuchen,” 1826 (while admitting Prout’s priority), that independ- 
ently they had found hydrochloric acid in distilling various gastric fluids, and a month 
later first saw Prout’s publication. However, Prout was clearly ahead of them, both in the 
distillation method, and in its ingenious confirmation by analytical results, as described in 
the text. ; 

5 Compt. rend. Acad. d. sc., Paris, 1844-5 ; ‘‘Lecons de physiol. exper. appliqué a la . 
méd.,” 1856, tome ii. p. 397. 

6 Ber. d. Sachs. Gesellsch. d. Wissensch., Leipzig, 1847. 

7 Pelouse, Compt. rend. Acad. d. sc., Paris, tome xix. p. 1227; Thomson, Lond. 
Edin. and Dub. Phil. Mag., London, 1845. 

8“ Traité analytique de la digestion,” 1843; Jahresb. ti. d. Fortschr. d. ges. Med., 
Erlangen, 1851, Bd. i. S. 97 ; 1858, Bd. i. S. 37. 

® See p. 361. 

10 «Die Verdauungssifte und der Stoffwechsel,” Mitau u. Leipzig, 1852, S. 44. 


THE ACEP CORTHE GASTRIC JUICE. 353 


the result of eighteen concordant analyses, Schmidt found that gastric 

juice always contained more hydrochloric acid than was sufficient to 

neutralise all the bases present, and that the excess of hydrochloric acid 

was alone sufficient to account for the entire acidity of the gastric juice. 
Schmidt's course of procedure was as follows :— 


The total chlorides in a weighed quantity (100 grms.) of gastric juice 
were precipitated and weighed as silver chloride in the usual fashion, by 
adding a drop or two of nitric acid followed by slight excess of silver nitrate 
solution. From the filtrate the excess of silver nitrate was removed by addi- 
tion of pure hydrochloric acid, as silver chloride ; and the filtrate, containing 
all the bases of the gastric juice, was evaporated to dryness, ignited, and the 
amount of each separate base in the ash determined by appropriate methods. 
In many cases the percentage of ammonia present was also determined in a 
different portion as ammonio-platinic chloride. 

The amount of hydrochloric acid present, combined and uncombined, was 
found from the weight of the first silver chloride precipitate ; the weight of 
chlorine necessary to combine with the weight of each base present was next 
calculated, on the assumption that all of each base was actually present as 
chloride ; and by adding all these weights of chlorine the amount of chlorine 
(and hence hydrochloric acid) necessary to satisfy all the bases was determined. 
This was found to be considerably less than the total chlorine present ; in fact, 
the difference in the two amounts represented very accurately the total acidity 
reckoned as hydrochloric acid. 

The argument underlying Schmidt’s experiments cannot be gainsaid, 
and as the experimental part of his work was confirmed by other 
observers, there remained no choice but to accept the presence of 
hydrochloric acid in the stomach as proven. This view accordingly 
gained ground after the publication of his results, and is now universally 
accepted. 

Although Schmidt's experiments demonstrate that there is an excess 
of hydrochloric acid in gastric juice, uncombined with inorganie bases, they 
do not show that this excess of acid is entirely uncombined. It is 
certain that if the excess of acid is in chemical combination with any- 
thing, the compound so formed is a very unstable one; this is shown by 
the ease with which the acid combines with fixed alkalies, and by the 
persistence of the acid reaction in spite of the combination. Still there 
are clear grounds for believing that the hydrochloric acid is in most 
cases combined loosely with some other body, most probably albumose 
or peptone, which are always present in traces in gastric juice. These 
reasons are as follows :— 


1. Organie acids do not dissolve calcium oxalate, but a solution of 
hydrochloric acid in water, containing one part of acid in a thousand 
parts of water, does dissolve this compound. Now gastric juice does not 
dissolve calcium oxalate, from which Bernard and Barreswil? argued that the 
acidity of gastric juice is not due to hydrochloric acid. This difference in 
action on calcium oxalate of (a) a solution of hydrochloric acid in water, and 
(4) gastric juice, is, however, probably due to the presence of albumoses and 
peptones, which form a loose combination with the acid, of sufficient stability 
to prevent it from acting’on calcium oxalate. 


1Ch. Richet, ‘‘Le suc gastrique chez ’homme et les animaux,” Paris, 1878, p. 32; 
Maly, Ann. d. Chem., Leipzig, 1874, Bd. elxxiii. S. 227. 
* Cl. Bernard, “Tecons de phy siol. expér.,” 1856, tome il. p. 395. 


VOL. I.—23 


354 CHEMISTRY OF THE DIGESTIVE PROCESSES. 

2. Laborde! compared the inverting power of gastric juice on cane-sugar 
with that of a solution of pure hydrochloric acid in water, of equal acidity to 
the gastric juice, and under similar conditions. He found that the hydro- 
chloric acid inverted much more rapidly than the gastric juice, which 
possessed much the same inverting power as a solution of lactic acid of equal 
concentration. He also found that gastric juice converted starch into grape- 
sugar and dextrin much more slowly than a solution of hydrochlorie acid 
under similar conditions. On the other hand, Szabo * found that peptones do 
indeed interfere with the action of dilute hydrochloric acid on starch; but, 
contrary to Laborde, found that the action of gastric juice on starch lies in 
intensity much closer to that of hydrochloric than to that of lactic acid. 

3. In treating of the digestive enzymes, it has been seen that these are 
much less injured by hydrochloric acid, in presence of albumoses and peptones, 
than by free hydrochloric acid alone, which shows that hydrochloric acid in 
presence of albumoses and peptones behaves as if it entered into combina- 
tion with them. 

4, Berthelot and Jungfleisch * showed that, when a substance which is 
soluble in each of two solvents, which are not completely soluble in each 
other, is shaken up with a quantity of both solvents, it divides itself between 
the two solvents so that the ratio of its concentrations in each is constant, and 
does not vary with the proportion of the two solvents used, nor the amount of 
soluble material used. This constant ratio they called the coefficient de 
partage, which may be rendered in English “coefficient of distribution.” 4 
For example, if succinic acid be well shaken up with water and ether, the 
concentration of succinic acid in the watery layer will always be about six 
times as great as in the ethereal layer, no matter, within wide limits,° what 
have been the quantities of ether, water, and succinic acid used; the co- 
efficient of distribution is here six. Mineral acids are much more soluble in 
water compared with ether than are organic acids; accordingly the co- 
efficients of distribution of the mineral acids for these two solvents are 
much larger than those of the organic acids, 

Richet ° made use of this property to test whether pure gastric juice con- 
tains only hydrochloric acid, or hydrochloric acid plus organic acids. He 
found that the coefficient of distribution was 13771. To a portion of the 
same gastric juice he next added barium lactate, and found that the co- 
efficient was reduced to 9-9, that of lactic acid is 8-8 to 11-0. This experiment 
shows that the acid first present was a mineral acid, which afterwards dis- 
placed nearly all the lactic acid from combination, so that in the second case 
the acidity was mainly due to lactic acid. Richet further added sodium 
acetate (a) to a solution of hydrochloric acid in water ; ()) to gastric juice of 
equal acidity, and found that in the first case the coefficient was reduced to 
1-7 (practically that of acetic acid, 1-4), while in the second case the co- 
efficient was only reduced to 5 to 5°8. Richet supposes that this difference is 
due to the hydrochloric acid in the gastric juice being combined feebly with 
some other substance. When sodium acetate is added to hydrochloric acid 
alone, the base will be shared between the two acids in proportion to their 
mutual avidities for it, which are in the ratio of 1 to ‘03. That is to say, about 


1 Gaz. méd. de Paris, 1874, Nos. 32-34, pp. 399, 411, 422. 

? Zischr. f. physiol. Chem., Strassburg, 1877, Bd. i. S. 140. 

5 Ann. de chim., Paris, 1872, Sé. 4, tome xxvi. p. 396. For a complete account of 
this subject, see Ostwald, ‘‘ Lehrbuch der allgemeinen Chem.,” Leipzig, 1891, Aufl. 2, 
Bd. i. S. 809. 

4 This term has been proposed by Gamgee, ‘‘ Physiological Chemistry,” vol. ii. p. 97, 
as well as ‘‘ coefficient of repartition.” 

° The quantities of solvent must be so chosen, compared with the quantity of soluble 
substance, that the solutions are not too concentrated. 

6 «“Le sue gastrique chez homme et les animaux, ses propriétés chemiques et physio- 
logiques,” Paris, 1878, p. 37. 


THE ACID OF ‘THE GASTRIC JUICE. 355 


97 per cent. of the base will be combined with the hydrochloric acid, and 
3 per cent. with the acetic acid ; or, otherwise, 3 per cent. of the hydrochloric 
acid will be free and 97 per cent. of the acetic acid, supposing that equivalent 
quantities of the two acids are present.!. Such a mixture would possess only 
a slightly higher coejicient of distribution than acetic acid. But if the 
sodium acetate be added to hydrochloric acid, already feebly combined with 
something else, the power of the acid to combine with the sodium will be 
diminished, on account of the tendency to remain combined with this sub- 
stance, and the amount of hydrochloric acid uncombined with sodium will be 
increased ; this will remain to a greater extent in the watery layer, and on 
shaking itl ether the coefficient of distribution will be much greater than 
that of acetic acid. 

Richet found traces of leucine in the gastric mucous membrane, and _be- 
lieves, mainly on this ground, that the hydrochloric acid of the gastric juice 
is In combination with somone: But there is no good reason for going so far 
afield to seek a partner for the hydrochloric acid; any substance in combination 
with the acid would produce such an effect as Richet obtained, and it is far 
more probable that the hydrochloric acid is in combination with the albumoses 
of the gastric juice than with leucine, especially as leucine has not been found 
in gastric juice, and hydrochlorate of leucine does not act as an acid to pepsin, 
as shown by the inability of a mixture of the two to digest proteids.” 

This account of Richet’s work has been placed here on account of the bear- 
ing of the latter part of it on the question of the combination of the hydro- 
chlorie acid, but the first part of it is also of great value in showing that pure 
gastric juice is practically free from organic acid. 


Organtie acids present during carbohydrate digestion. — Although organic 
acids are entirely absent in pure gastric juice, or at most are only present 
in traces, this is by no means the case during digestion, especially of food 
rich in carbohydrates. 

The food passing into the stomach during a meal is alkaline in 
reaction, by reason of the saliva with which it is abundantly mixed; and 
in addition, during and after a meal a considerable quantity of saliva is 
swallowed by itself. As Beaumont? and others have shown, there is no 
secretion of acid gastric juice when the stomach is empty, and although 
active secretion begins with the arrival of the first portions of food in 
the stomach, some time must elapse before the alkaline reaction of the 
masses of food and saliva is neutralised by the acid of the gastric juice, 
and a reaction due to free hydrochloric acid established, after saturation 
of the soluble proteid of the food. This interval is exceedingly difficult 

‘to estimate, the delicate colour reactions for free hydrochloric acid being so 
deceptive in a heterogeneous fluid like the contents of a stomach; 
van de Velden‘ states that it varies from half an hour to two hours, 
and is on an average three-quarters o an hour. During this time con- 
version of starch ‘by ptyalin goes on,> and in addition “bacterial action 
begins with the production, from the carbohydrate part of the food, of 
lactic acid,® accompanied by traces of butyric and acetic acids. 

1J. Thomsen, ‘‘ Thermochemische Untersuchungen,” Ann. d. Phys. uw. Chem., Leipzig, 
1869-1871, Bde. exxxvili.-exlili. 

2 See Gamgee, ‘‘ Physiological Chemistry,” vol. ii. pp. 97-99. 

8 See article on ‘‘ Mechanism of Gastric Secretion.” 

+ Ztschr. f. physiol. Chem. , Strassburg, 1878, Bd. ii. S. 205. 

5 See under ‘‘ Ptyalin,” p. 329. 

® According to Maly, the greater part of the lactic acid is the ordinary lactic acid of 
fermentation, ‘but this is accompanied by a smaller quantity of sarcolactic acid, which may 


occasionally be much increased in amount, Ber. d. deutsch. chem. Gesellsch., Berlin, 1874, 
S. 156; Ann. d. Chem., Leipzig, 1874, Bd. “clxxiii, S. 227. 


” 


356 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


It was long believed that this action was due to the growth of the 
Bacillus acidi lactici on sugar only, either that of the food or that produced 
by the action of ptyalin on the starch of the food. Briicke? has shown, 
however, that starch can be also changed into lactic acid without con- 
version by ptyalin, by demonstrating that soluble starch, erythrodextrin 
and lactic acid, are found in the stomach of the dog after a meal contain- 
ing boiled starch. Now the saliva of the dog contains no ptyalin, so that 
these products must be formed directly from starch. Traces of sugar 
are also found, and Briicke supposes that sugar is first formed by the 
action of the bacterium but immediately becomes converted into lactic acid 
by its further action. A similar change in starch paste takes place on 
standing in the air. 

Goldschmidt? divides gastric digestion in the horse into four stages, 
which are, however, not sharply marked off, but merge ito one another. 
(1) No proteolysis, acid reaction due to lactic acid. (2) Proteolysis 
and amylolysis proceed together, both lactic and hydrochloric acids 
present. (5) Stoppage of amylolysis in the middle part of the stomach, 
in this portion only hydrochloric acid, elsewhere lactic acid. (4) Stop- 
page of amylolysis everywhere; hydrochloric acid only present in all 
parts of the stomach. Ewald and Boas® describe a similar state of 
affairs in the healthy human stomach under normal conditions after 
a carbohydrate meal. In the first stage (from ten to thirty minutes after 
the meal) lactic acid alone is present; in the second, lactic and hydro- 
chloric acids are present together, but the former rapidly disappears so 
soon as any free hydrochloric acid is present; and in the third stage, 
hydrochloric acid alone is present. This disappearance of the lactic acid 
is very interesting, as showing that it is rapidly absorbed in the 
stomach. 

Other inorganic acids free in pure gastric juice besides hydrochlorie 
acid.—It must not be assumed, from the usual mode of stating the 
results of quantitative analysis of gastric juice,* that hydrochloric acid is 
the only inorganic acid present in the gastric juice. All the phosphoric 
acid is not united, in the gastric juice, to calcium, magnesium, and iron 
to complete saturation, as usually set forth in such analytical results ; 
nor are all the bases saturated by the hydrochloric acid, and only that 
amount of hydrochloric acid free, which is left over after so saturating 
them.® Suppose a solution in water of neutral chlorides is taken, say 
such a solution as the gastric juice would be, minus its free hydrochloric 
acid and its phosphates, and to this phosphoric acid is added. As soon 


1 Briicke, Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1872, Bd. lxv. Abth. 3, S. 126 ; 
** Vorlesungen,” Wien, 1885, Aufl. 4, Bd. i. S. 321. See also W. de Bary, Arch. f. exper. 
Path. u. Pharmakol., Leipzig, 1886, Bd. xx. S. 243. 

* Zischr. f. physiol. Chem., Strassburg, 1886, Bd. x. S. 361. See also Ellenberger and 
Hofmeister, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1885, Bd. xv. 8. 284, 301 ; 
1886, Bd. xvi. S. 260, 261. 

® Virchow’s Archiv, 1885, Bd. ci. S. 325; 1886, Bd. civ. S. 271; Ewald, ‘‘ Klinik der 
Verdauungskrankheiten,” 1890, Bd. i. S. 83. 

* See p. 350. 

° This was merely an assumption made by Schmidt, in order to conclusively show that 
gastric juice contained an excess of hydrochloric acid above even this quantity. Fortunately, 
the excess of hydrochloric acid was sufficient to allow Schmidt to give this form of proof; 
but if the quantity of phosphates had been greater, or the excess of hydrochloric acid less, 
Schmidt's process might easily have yielded a negative result, and yet the gastric juice 
have contained free hydrochloric acid ; indeed, the massed equivalent in chlorine of the total 
bases might have been greater than the total quantity of chlorine present, and still there 
might have been free hydrochloric acid present. 


THE ACID OF THE GASTRIC JUICE. 357 


as the phosphoric acid passes into solution, it no longer remains present 
as free phosphoric acid, to the amount to which it has been added, but 
reacts with the other salts present in solution, displacing a definite 
amount of each metal from combination with chlorine, thus setting free 
hydrochloric acid and forming phosphates, so that there comes to be in 
solution free hydrochloric acid and free phosphoric acid, combined 
phosphoric acid, and combined hydrochloric acid (that is, chlorides and 
phosphates). When a polybasie acid, such as phosphoric acid, is present 
in solution, the matter is somewhat further complicated by there being 
certain steps between free acid and combined acid, namely, acid salts ; 
these also are represented in the distribution of bases among the acids, 
so that there are in solution free acids, acid salts, and neutral salts. In 
pure gastric juice, then, the acidity is in chief due to hydrochloric acid, 
but also in part to acid phosphates and phosphoric acid, and the amount 
of each of these free is perfectly determinate, and depends upon the 
amount of each base and each acid present. For one fixed distribution 
only can there be chemical equilibrium in the solution; the introduction 
of any salt, acid, or base into the solution will alter this equilibrium, and 
a new distribution to suit the new conditions will occur, giving rise 
again to equilibrium. 

The facts stated above follow directly from Thomsen’s! “avidity 
law.” Thomsen arrived at this law by comparing the amount of heat 
set free when an equivalent weight of a base unites with a mixture of 
equivalent weights of two different acids, with the amount set free when 
it combines with each acid separately.2, The law is that no acid in solu- 
tion is combined with the bases present, to the complete exclusion of 
other acids, however weak (as it is popularly expressed), which may be 
simultaneously present in the solution; but the acids share the bases, 
according to their different avidities. Thomsen worked out a number of 
avidity coefficients. Those of the organic acids are much smaller than 
those of the inorganic acids. Thus, taking the avidity coefficient of 
hydrochloric acid as unity, that of oxalic acid is ‘25, tartaric acid -05, 
acetic acid ‘03. These coefficients mean, for example, that if one 
equivalent each of sodic hydrate, of hydrochloric acid, and of oxalic acid, 
be mixed in solution together, four-fifths of the base is combined with 
the hydrochloric acid and one-fifth with the oxalic acid, and con- 
sequently one-fifth of the hydrochloric acid is free and four-fifths of the 
oxalic acid. 

Maly? has also shown qualitatively, by a method of diffusion, that 
this displacement of a strong acid (ze. acid with a large avidity co- 
efficient) by a weak acid (acid with a small acidity coefficient) takes 


1 <«Thermochemische Untersuchungen,” Ann. d. Phys. u. Chem., Leipzig, 1869-71, 
Bde. exxxviii.—cxliii. 

2 Let a be the amount of heat in heat units developed when, say, one equivalent of 
NaOH in grammes combines with one equivalent of HCl, and } that when it combines 
with an equivalent of HNO,, ¢ that when it partially combines with a mixture of one 
equivalent of HCl and one equivalent of HNO,, also let x be the fraction which combines 
with HCl. Then, since @ is the amount of heat set free when a whole equivalent of 
NaOH unites with HCl, a x will be that set free when the fraction zx combines ; similarly 
b (1—z) will be the amount set free by the combination of the fraction (1—) with HNO,; 
the sum of these two must equal c, the amount of heat actually observed ; therefore a + 
6 (1—2z)=c, from which vz and 1—z can be determined. Their ratio is the measure of the 
avidity of the two acids for combining with the base. 

3 Ann. d. Chem., Leipzig, 1874, Bd. clxxiii. S. 250; Sitzwngsb. d. k. Akad. d. 
Wissensch., Wien, 1874, Bd. lxix. Abth. 3, S. 251; Ztschr. f. physiol. Chem., Strassburg, 
1847, Bd. S. 174. 


358 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


place in solution. He dissolved sodium chloride and lactic acid together 
in water, placed the solution in the bottom of a cylindrical vessel, and 
then carefully poured a layer of distilled water on the top. After some 
days, part of the upper layer was removed and analysed ; it was found to 
contain more than sufficient chlorine to balance all the sodium present ; 

that is to say, it contained free hydrochloric acid. Similar results were 
obtained with a mixture of monosodium phosphate, and other acid salts, 
in common solution with sodium chloride. 

These results of Thomsen and Maly will be again referred to in 
discussing the mode of origin of hydrochloric acid. They are introduced 
here to show that any weaker acids in gastric juice ‘along with the 
hydrochlorie acid m ust in part be uncombined. Any organic acids 
present during digestion will also be in part free and in part. combined, 
and as these have very small avidities compared with hydrochloric acid, 
they will be almost completely free. This has a bearing ‘of some import- 
ance. Any organic acids formed in the stomach by bacterial action on 

carbohydrates will be found as free acids, and will not reduce the amount 
of free hydrochloric acid? but salts of organic acids entering the stomach 
with the food will reduce the amount of acidity due to free hydrochloric, 
because, from the organic salts, free acids will be formed, by hydrochloric 
acid combining with their bases. 

Source of the hydrochloric acid—The only possible source of chlorine 
lies in the chlorides of the food, and from this either directly, or indirectly 
through the blood, the hydrochloric acid must necessarily have its origin. 
That the chlorides present in the blood plasma are the source of the acid, 
has been experimentally proved by Voit? and Cahn.? 

Following a method first used by Voit, Cahn fed dogs exclusively 
on meat which had previously had all its salts extracted by boiling it 
repeatedly with distilled water. An animal fed in this manner continues 
to excrete a diminishing quantity of chlorides in the urine for a period 

varying from two to five days. After this only traces of chlorides are 
found in the urine, but the tissues and blood still cling on to their 
necessary minimum quantity of chlorides, digestion goes on, and the 
animal lives. At this period, if the contents of the stomach are washed 
out with distilled water, the secretion is found to contain free acid and 
to possess digestive power. If now the animal’s reserve stock of chlorine 
be still further reduced by administering diuretics, such as potassium 
nitrate, which cause some additional chlorides to be excreted ; or if free 
hydrochloric acid be repeatedly removed by pumping out the contents of 
the stomach with the aid of distilled water, a condition is finally reached 
in which the stomach secretes a completely neutral fluid, which is 
altogether inactive so long as it is neutral, but quickly digests fibrin if 
1 part per 1000 of hydrochloric acid be added to it. When this 
stage is reached the animal rapidly fails; but if a small quantity of 
sodium chloride be now given to it, it rapidly recovers, and soon becomes 
in every respect normal. 

This experiment also shows that the secretion of pepsin is independ- 
ent of that of acid, and that in the absence of hydrochloric acid no 


1 In fact will slightly increase it by combining to a certain extent with the bases of the 
chlorides. 

2 Sitzungsb. d. k.-bayer. Akad. d. Wissensch. zu Miinchen, 1869, Bd. ii. S. 483. See 
also M. Gruber, Beitr. z. Physiol. C. Ludwig z. s. Geburtst., Leipzig, 1887. 

3 Ztschr. f. physiol. Chem., Strassburg, 1886, Bd. x. S, 522. 


PAL? ele eal 


THE ACID OF THE GASTRIC JUICE. 359 


lactic acid or other organie acid is formed, which disproves the theory 
that lactic acid is first formed and then decomposes sodium chloride, so 
forming free hydrochloric acid. 

It may here be pointed out that experiments have been made by 
Nencki and Schoumova-Simanowsky? to ascertain the possibility of 
replacing the chlorine by other halogens, so as to form hydrobromic or 
hydriodic acids. These experiments were performed on dogs operated 
on by Pawlow’s method,? and the animals were fed with food in which 
sodium chloride was as far as possible absent. Some had added to their 
food sodium bromide, others sodium iodide. The administration of 
sodium bromide resulted in the animals becoming so ill after a week or 
so that the experiments had to cease. The gastric juice was secreted as 
before, but the hydrochloric acid was largely replaced by hydrobromic 
acid. In the case of those dogs to which sodium iodide was administered, 
though less general disturbance resulted from the administration than 
was the case with sodium bromide, yet the amount of hydriodic acid 
replacing hydrochloric acid was very small. 

Reciprocity between the secretion of hydrochloric acid and the reaction 
of the urine—That the hydrochloric acid of the gastric juice is formed 
from the chlorides of the blood plasma, is likewise shown by Maly’s* 
observation that at the same period after a meal at which the secretion 
of gastric juice is at a maximum, the acidity of the urine is at a minimum, 
and may be replaced by an alkaline reaction. One function of the kidneys 
is to preserve unaltered in degree the alkalinity of the blood. If now 
neutral salts, such as sodium chloride, be removed from the blood, split 
up in some manner by the agency of the gastric gland cell into hydro- 
chlorie acid and sodic hydrate, of which the hydrochloric acid is sent 
towards the stomach cavity, while the alkali is expedited in the opposite 
direction back to the blood stream, it follows that the alkalinity of the 
blood will be increased. Hence, to preserve equilibrium, the kidneys 
must excrete a less proportion of acid salts, or, if the rate of increasing 
alkalinity of the blood demands it, must separate an alkaline fluid from 
the blood. This is experimentally found to be the case. Under ordinary 
circumstances, the kidneys preserve the constant value of the alkalinity 
of the blood, by excreting phosphates of the alkalies so proportioned that 
the reaction is acid, but during active digestion, 2 to 4 hours after a full 
meal such as dinner, the relative amounts of bases and phosphoric acid 
are so altered that the reaction becomes neutral or faintly alkaline, or, as 
it is often commonly but not very exactly expressed, in the first case 
monosodic phosphate (NaH,PO,) is secreted with acid reaction; in the 
second, disodie phosphate Na,HPO, with alkaline reaction.’ 

Theories as to the mode of origin of the hydrochloric acid.—Many 
ingenious theories have been proposed to account for the specific function 
of the gland cells of the stomach, of splitting up such a stable substance 

1See p. 352. 

2 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1894, Bd. xxxiv. 8. 313. 

3 See article on ‘‘ Mechanism of Gastric Secretion.”’ 

4 Ann. d. Chem., Leipzig, 1874, Bd. clxxiii. S. 232. See also Quincke, /ahresb. i. d. 
Fortschr. d. Thier-Chem., Wiesbaden, 1874, Bd. iv. S. 241; Stein, ibid., 1876, Bd. vi. 
i * The reaction will really vary according to the relative amounts of base and acid 
present. Monosodic phosphate alone dissolved in water has an acid reaction, disodic 
phosphate similarly has an alkaline reaction, and mixtures in varying proportions can 


have acid, neutral, or alkaline reaction. Ina complex mixture such as urine, no one can 
say to what the reaction is due, but only that there is an excess of alkali or acid. 


360 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


as sodium chloride, of forming such a strong acid as hydrochloric acid is 
in the face of the alkalinity of the blood, and of determining an alkaline 
stream towards the blood and an acid stream towards the lumen of the 
gland. 

The oldest theory was, that the process was an electrolytic one. 
Blondlot! supposed that by electric agency sodium chloride in the 
stomach wall was broken up into sodic hydrate and hydrochloric acid 
(in the language of to-day, hydrolysed, NaCl+ H,O=NaHO-+ HC). 
The free acid then, for the most part, acted on the caleium phosphate 
of the blood, forming acid phosphate and a trace of phosphoric acid, 
while a trace of hydrochloric acid also remained free. To such a mixture 
of acid substances (mainly acid calcium phosphate) he ascribed the 
acidity of gastric juice. He electrolysed tricalcic phosphate, suspended 
in a solution of sodium chloride, and claimed to have obtained such 
products as his theory demands. Briicke* considered that the energy 
required came from transformation of nervous energy, modified to this 
purpose, and, admitting that the details are not explicable, compared the 
effect to others called forth by nerve impulses, such as the electric effects 
in the electric end-organ of some fishes. He also considered the secretion 
of acid more analogous to electrolysis than to any other known process. 
Lussana ? supposed that in the glands of the stomach a decomposition of 
the salts of the plasma took place, and that the preponderating part of 
the free acid of the gastric juice was hydrochloric, simply because by far 
the greater part of ‘the salts of the plasma are chlorides. He tried to 
test his theory by intravenous injection of salts not present in quantity 
in blood plasma, such as sulphates and phosphates. He did not, 
however, obtain the corresponding acids in the gastric juice, except 
in the case of borax and tartar emetic, after injection of which traces 
of boric and tartaric acids respectively were found in the gastric Juice. 

Buchheim* suggested that the chlorides of the plasma combined 
with the proteid, so that the metal combined with one proteid molecule 
and the acid radicle with another; the latter combination being absorbed 
by the acid-secreting cells and broken up there into proteid and acid. 

These older theories can at best be only regarded as mere specu- 
lations; there is absolutely no experimental proof of them. Nor can 
we lay claim at the present day to a complete knowledge of the 
process of secretion of hydrochloric acid. Only thus far the progress 
of physical chemistry, and a more exact knowledge of the laws of 
solutions, has brought us, that we no longer need look upon the 
production of hydrochloric acid by the animal organism as a chemical 
wonder. The secretion of hydrochloric acid is still a mystery as great 
as the secretion of pepsin or any other product of cell activity, but 
no greater. 

To the chemist, before the thermochemical work of Thomsen, and 
the diffusion experiments of Maly already described,’ and when he was 
acquainted with no other means of setting free hydrochloric acid from 
its salts than the electric current or displacement by a stronger acid 
such as sulphuric acid, the occurrence of hydrochloric acid in the gastric 

1“ Traité analytique de la uigerticn, ” Nancy et eee 1843; Jahresb. ii. d. Fortschr. 
d. ges. Med., Erlangen, 1851, Bd. i. S. 97 ; 1858, Bd. i. S. 87. See also Ralfe, Lancet, 
London, 1874, vol. ii. p. 29. 

a “ Vorlesungen, mien: 1885, Anti 45 Rheteasi3 Ore 


3 Jahresb. i. d. Fortschr. d. ges. Med., Erlangen, 1862, Bd. i. S. 110. 
4 Arch. f. d. ges. Physiol., Bonn, 1876, Bd. xii. S. 332. > See p. 357. 


s 


THE ACID OF THE GASTRIC JUICE. 361 


juice was an unsolvable riddle. But when Thomsen had shown that 
the weakest acid is in some measure capable of displacing the strongest 
from its salts, and Maly that by a simple process of diffusion this strong 
acid may be afterwards separated, the subject assumed a different aspect. 
It was no longer necessary for the cell to be endowed with some force 
of sufficient intensity, to directly break up such stable substances as the 
alkaline chlorides. All that was necessary was that the cell should be 
able from the organic material at its disposal to form an organic acid, 
and afterwards to rapidly excrete the small fraction of hydrochloric 
acid formed by the interaction between this organic acid and the neutral 
chlorides, so that a fresh quantity of hydrochloric acid may be formed 
by the mass action of the remainder of the organic acid on the remainder 
of the chlorides. The organic salts so formed can then decompose by 
cell activity into organic acid and base again, and the base be returned to 
the blood stream. Since gastric juice is not accompanied by an organic 
acid, this must be retained in the cell and induce a continuous cyclic 
change. It is thus possible, with the aid of the new facts of physical 
chemistry, to see that the process of secretion of hydrochloric acid can 
be reduced to the same level as that of the secretion of any organic 
material. 


This, however, is but a small portion of the entire problem. As Bunge 
says: ‘‘In the appearance of the free hydrochloric acid lies nothing puzzling. 
Puzzling only is the power of the epithelial cell to send the hydrochloric acid 
freed from the sodium chloride streaming always in one direction towards the 
lumen of the gland, and the sodium carbonate! simultaneously formed always 
back in the opposite direction towards the lymph and blood channels. But 
such a puzzle we meet everywhere in the living tissue. Every cell possesses 
the power to dispose of material in a suitable manner, attracting or repelling 
it and sending it streaming in different directions.” ? 


Maly’s theory.—Maly has attempted to build on a purely physical 
basis a theory of the formation of hydrochloric acid from the chlorides of 
the blood, of which the following are the outlines : #— 

1. There are no theoretically alkaline salts in the blood. Blood 
plasma owes its alkalinity to two theoretically acid salts, di-sodic 
phosphate (Na,HPO,), and sodium bicarbonate (NaHCO,); besides 
these two acid salts plasma contains excess of carbonic acid. 

2. Disodic phosphate in presence of calcium chloride forms some 
free hydrochloric acid, thus :—3CaCl,+2Na,HPO, = Ca.(PO,),+4NaCl+ 
2HC14 

Chiefly from the facts above stated, Maly supposes that by the 
interaction of these theoretically acid salts of the plasma, on the chlorides 
present with them in solution, traces of hydrochloric acid are formed; 
these traces of hydrochloric acid are rapidly removed, on account of the 
high diffusibility of hydrochloric acid,’ by the gland-cells which act as a 

1 Bunge is considering the hydrochloric acid as set free by the action of car bonic acid. 

2 Somewhat freely translated from Bunge, ‘‘ Lehrbuch der physiol. Chemie,” Leipzig, 
1894, Aufl. 3, S. 148. 

3 ipsbeneted from Maly, Hermann’s ‘‘ Handbuch,” Bd. v. (2), S. 66. 

4R. Pribram, Jahresb. ii. d. Fortschr. d. Thier- Chem., W iesbaden, 1871, Bd. i. S. 107; 
Gerlach, ibid., 1873, Bd. iii. S. 109. 

5Graham has shown that the free acids diffuse more rapidly than their salts; HCl 
diffusing thirty-four times as rapidly as NaCl. Graham was also the first to show that, by 


diffusion of acid potassium sulphate, sulphuric acid was obtained in the dialysate, while 
normal sulphate remained behind. 


362 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


perfect diffusion? apparatus; on the removal of the hydrochloric acid, 
fresh acid is formed by further mass action on the chlorides. The 
kidneys or sweat glands probably do not so secrete hydrochloric acid, 
because they are not such perfect diffusion arrangements as the gastric 
glands, and cannot bring about such a molecular separation as the latter. 

Objections to Maly’s theory.—1. Modern work has shown that the 
alkaline reaction of theoretically acid salts is probably due to a hydro- 
lysis taking place on solution. Thus on dissolving sodium bicarbonate 
there are formed sodic hydrate and carbonic acid (NaHCO, +H,O=NaOH 
+H,CO,): and the sodic hydrate being a powerful base, and. the car- 
bonic acid a weak acid, one equivalent of the base more than balances 
two of the acid, and the reaction is alkaline. On the other hand, when 
acid potassium sulphate is dissolved, there is one equivalent in solution 
of a strong base, and two equivalents of a strong acid, and the reaction 
is acid. Such an hydrolysis of phosphates of the alkalies also takes 
place. Trisodie phosphate yields an equivalent of base to one of acid, 
and the reaction is intensely alkaline; disodie phosphate yields only two 
equivalents of base to three of acid, but the reaction is still alkaline; 
while monosodic phosphate yields but one equivalent of base to three of 
acid, and at last the reaction is acid. A mixture of mono- and disodie 
phosphates in proper proportion would be neutral. In fact, after these 
salts are dissolved, they no longer exist as such, but there are present in 
solution bases and acids in certain concentrations, and the reaction of the 
solution will depend on which of these acts most strongly on the in- 
dicator. Now the hydrolysing effect on the neutral salts, chlorides, ete. 
Gf such are also present in solution), of these so-called acid salts must 
closely resemble their effect on the indicator. 

Whether there will be a tendency to formation of hydrochloric acid 
or not from sodium chloride, will be determined by whether the attraction 
of the acids (phosphoric and carbonic) for the base is greater or less 
than the attraction of the bases for the hydrochloric acid. The reaction 
of the solution of phosphates and carbonates in the plasma is alkaline, 
which shows that the latter is the case, and that, therefore, there will be 
no hydrochloric acid formed. 

2. The continuous formation of hydrochloric acid by a reaction 
between disodic phosphate and calcium chloride is impossible, because it 
necessitates the formation of insoluble tricaleic phosphate, and as the 
supply of calcium chloride is small, must soon stop. 

3. Even if it be admitted that there are traces of hydrochloric acid 
in the blood, there is no reason, if the process be purely one of diffusion, 
why it should not go on continuously. This it does not do, but ceases 
when digestion is not going on, and when digestion begins is secreted in 
such amount that no mere physical diffusion could bring it through the 
epithelial cells fast enough; not to speak of separating it from a fluid 
in which it is supposed to be present in traces only2 

‘By a perfect diffusion apparatus (vol/kommener Diffusions-apparat) Maly seems to 


mean here semipermeable membrane ; that is, an arrangement permeable to the hydrochloric 
acid and not to the other dissolved substances. 

* Gastric juice contains at least 2 parts per 1000 of hydrochloric acid ; the amount of 
hydrochloric acid formed by mass action in a solution of 6 parts per 1000 of sodium 
chloride, and a still smaller quantity of monosodium phosphates, no one has ever attempted 
to measure, but it must be many thousand times less than this ; so that not only must the 
hydrochloric acid diffuse with a tremendous velocity, but it niust get infinitely more con- 
centrated in the process of diffusion, which, under purely physical conditions, so far as 
we know them, is an utter impossibility. 


a 08 


THE ACID OF THE GASTRIC JUICE. 363 


These facts indicate that the formation of hydrochloric acid is a 
process going on in the cell, that the acid is a cell secretion, and not a 
diffusate from the blood plasma. 

Gamgee's modification of Maly’s theory—Gamgee, while retaining 
the supposition that the hydrochloric acid is formed by the action ot 
the alkaline phosphates on the chlorides, removes the seat of action from 
the blood to the parietal cells. He supposes that these cells possess a 
peculiar selective absorption for the phosphates of sodium, both alkaline 
and acid, and for chlorides, and that within the cell there occur the 
same reactions between these substances as occur 7m vitro when they 
coexist in solution. One of the products of the reaction will then be 
hydrochloric acid, which, in virtue of its high power of diffusion, will 
pass, as soon as formed, into the secretion of thegland. This supposition 
is certainly a step in the right direction, in so far as it brings the seat 
of action to the cell—a much more probable place than the blood—but, 
on the other hand, it assumes a good deal, without overcoming many of 
the objections to Maly’s theory. Thus, selective absorption, of both 
alkaline and acid phosphates (probably di- and mono-sodium phosphates) 
is assumed. Unless these are also assumed to be absorbed in such pro- 
portions that the reaction of the cell contents becomes acid, no formation 
of hydrochloric acid will take place, for, under merely physical conditions, 
no such formation can be demonstrated i vitro. 

Unless, again, the substances selectively absorbed are kept out of 
action in some equally obscure manner by cell activity, there is no 
reason why the secretion of acid should not be continuous ; ‘and if absor p- 
tion of phosphates and chlorides only begins at the commencement of 
digestion, it is not easy to see how the traces of hydrochloric acid, 
formed by such interactions, can keep pace with the demand then made 
for hydrochloric acid. 

Lastly, there is no experimental evidence that there is any such 
selective absorption of phosphates and chlorides by the parietal cells. 
And if a purely physical theory is to be abandoned, and a specific functional 
activity of the cell invoked, there remains no reason for adhering to 
theories which have been evolved on a purely physical basis. 

It is easier, and more in accordance with our notions regarding the 
secretion of other substances, to suppose that the hydrochloric acid 
is formed by cell activity in some metabolic process, from the chlorides 
and organic matters at its disposal. There are an infinite variety of 
such processes capable of taking place, under the varying conditions of 
cell life. It is true we do not know the details of these, nor why such 
processes take place under certain given conditions; nevertheless we 
see the end-results, and there is no reason why hydrochloric acid should 
not also be the end-product of such a cell metabolism rather than the 
product of a kind of specialised diffusion.” 


1 «¢ Physiological Chemistry,” 1893, vol. ii. p. 113. 

2 Hammarsten, ‘*Lehrbuch der physiol. Chem.,” Wiesbaden, 1895, Aufl. 3, S. 242. 
See also Heidenhain, Hermann’s Handbuch,’ Bd. vy. (1), 8S. 151. One such possible process 
is the formation in the cell of an organic acid which does not diffuse away, but is retained 
in the cell and exercises a continuous action on the chlorides, forming hydrochloric acid 
which the cell actively excretes. Another possibility would be the formation during 
-rest of an organic chlorine-containing substance, while the base combined with carbonic 
acid passed into the blood, and the subsequent breaking up during activity of this 
chlorine-compound yielding hydrochlori ic acid. There are indeed many courses which such 
a cell-metabolism might take ee hydrochloric acid ae an end-result. See also Bunge, 
“* Lehrbuch der physiol. Chemie,” Leipzig, 1894, Aufl. 3, S. 149. 


364 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


Function of the hydrochlorie acid—One obvious purpose of the 
hydrochloric acid of the gastric juice is to confer activity on the pepsin 
accompanying it, which is only active in an acid medium. But, as 
Bunge? points out, the establishment of an acid reaction is not necessary 
for proteid digestion. In the pancreatic juice another proteolytic 
ferment, trypsin, is found, which acts most powerfully on proteids in an 
alkaline medium. A much more important function of the hydrochloric 
acid lies, according to Bunge, in its powerful action as a disinfectant 
and germicide, in destroying bacteria introduced with the food. In this 
manner the formation of decomposition products, and the disturbance 
thereby produced in the normal course of digestion, is prevented, and 
also in many cases the animal is preserved from the attacks of patho- 
genic bacteria by the destruction of these or their spores. 

Modern research has, in fact, led to the remarkable result, that the 
average amount of hydrochloric acid found in the gastric juice just about 
coincides with that which is found experimentally to be required to stop 
the growth of most fermentative organisms and many pathogenic 
bacteria.? 

Spallanzani ? first called attention to the powerful preservative action 
of gastric juice, and not only showed that gastric juice prevented 
putrefaction, but that it stopped putrefaction which had already com- 
menced. This he showed by feeding dogs on pieces of flesh which had 
commenced to putrefy. After a short interval of gastric digestion the 
flesh lost all putrefactive odour. 


The action of the gastric juice on the bacilli of tubercle and splenic fever 
has been investigated by Falk,! and by Frank.’ Falk found that the bacillus 
of splenic fever (B. anthracis) is easily destroyed by gastric juice, but that 
its spores escape destruction, and that the tubercle bacillus is unaffected by 
gastric juice. Frank completely confirms these results, and both observers 
are agreed that the gastric juice is incapable of making any very effectual 
resistance to infection of the organism by these pathogenic bacteria. The 
comma bacillus of cholera, however, is readily destroyed by gastric juice or 
dilute hydrochloric acid. Cholera cannot be communicated by the mouth in 
healthy animals; but, after washing out the stomach with alkaline solutions, 
symptoms resembling those of cholera follow introduction of a pure culture of 
the cholera bacillus, as is also the case when this is introduced into the 
intestine. 

The acetic and lactic fermentations are stopped by mere traces of free 
hydrochloric acid, while acid combined with proteid is ineffectual. According 
to Cohn, this action is due to the free acid decomposing the alkaline phosphates, 
which are necessary for the growth of the bacteria.’ 


Qualitative tests for free hydrochloric acid in gastric juice—The 
many colour tests for detecting the presence of free hydrochloric acid 
Im gastric juice, in contradistinction to organic acids, are all more or 


’ “Lehrbuch der physiol. Chemie,” 1894, Aufl. 3, S. 141-145. 

* Sieber, Journ. f. prakt. Chem., Leipzig, 1880, Bd. xix. S. 433; Miquel, Centralbl. f. 
allg. Gsndhtspflg., Bonn, 1884, Bd. ii. S. 403. See also Ziemke, Inaug. Diss., Halle, 1893 ; 
Mester, Zéschr. f. klin. Med., Berlin, 1894, Bd. xxiv. S. 441 ; Schmitz, Ztschr. f. physiol. 
Chem., Strassburg, 1894, Bd. xix. S. 401. 

* «* Expériences sur la digestion,” Traduit par Senebier, Geneva, 1784. 

* Virchow's Archiv, 1883, Bd. xciii. S. 177. 

° Deutsche med. Wehnschr., Leipzig, 1884, No. 20, S. 309. 

° Nicati and Lietsch, Rev. seient., Paris, 1884, p. 658 ; Compt. rend. Acad. d. se., Paris, 
1884, tome xcix. S. 928; Koch, Deutsche med. Wehnschr., Leipzig, 1884, No. 45, S. 725. 

* Zischr. f. physiol. Chem., Strassburg, 1890, Bd. xiv. S. 75. 


Se 


THE ACID OF THE GASTRIC JUICE. 365 


less influenced by the presence of proteid or peptone, and cannot be 
much depended on for proving the entire absence of hydrochloric acid. 
The quantity of organic acid required to give the reaction in each case is 
much in excess of that present in the stomach, so that if the test gives a 
positive result this may usually be relied upon. 


The best of these reagents are the following :—(a) Gunzberg's reagent, 
which consists of 2 parts of phloroglucinol, 1 part of vanillin, and 30 parts of 
absolute alcohol. A few drops of this reagent and a few drops of filtered 
gastric juice are evaporated to dryness together, when, if free hydrochloric 
acid be present, a carmine-red mirror or carmine-red crystals are obtained. 
The test is unaffected by organic acids, but does not succeed in the presence of 
proteids or leucine ; it is said to detect 1 part of free acid in 20,000. (b) The 
tropeolin test.—Drops of a saturated solution of tropeolin in methylated spirit 
are allowed to evaporate on porcelain ; to the stain so left a drop of the solu- 
tion to be tested is applied, and the drop is evaporated at 40° C. In the 
presence of hydrochloric acid the result is a violet stain. The test has about 
the same delicacy as Gunzberg’s, and is subject to the same objections. 
(c) Reoch’s test? consists of a mixture of citrate of iron and quinine, and of 
potassium sulphocyanide. This is coloured red by a trace of a mineral acid, 
but not by dilute solutions of organic acid. Szabo* has modified this test into 
a quick, colorimetric quantitative method. He finds the Reoch test a satis- 
factory one, unaffected by chlorides, peptones, or the usual amount of lactic 
acid present in gastric juice. (d) Congo-red is strongly recommended by 
Gamgee,? either in aqueous solution, or as test paper made by saturating filter 
paper with it, and then drying. Traces of hydrochloric acid turn it an intense 
blue, while organic acids give a violet tint. 

Gentian- blue, methylaniline- -violet, malachite-green, and benzo-purpurin 
are other reagents which have been recommended as colour tests for traces of 
free mineral acids. 

Quantitative estimation of the free hydrochloric acid of the gastric juice.— 
Morner and Sjoqvist’s method.°—This method consists essentially in con- 
verting all the acids present into barium salts by shaking up with barium 
carbonate, drying, incinerating, and extracting thoroughly with warm water. 
In the process of incinerating, “the barium salts of the organic acids which may 
have been present are destroy ed and barium carbonate is ‘reformed ; the barium 
chloride formed from the hydrochloric acid alone dissolves afterwards! and 
gives, by estimating the barium, a measure of the amount of hydrochloric acid 
present. Using litmus as an indicator, 10 ¢.c. of the gastric juice is neutralised 
with finely-powdered barium carbonate in a platinum evaporating dish. The 
mixture is dried on the water bath, the residue incinerated, the ash powdered, 
extracted with as little warm water as possible, and finally filtered. The 
filtrate should measure about 50 c.c. To this filtrate an equal volume of 
absolute alcohol is added, and then three or four drops of a solution containing 
10 per cent. each of sodium acetate and acetic acid. Into this solution a 
standard solution of potassium bichromate, containing 8°5 grms. per litre, is 
run from a burette until all the barium is ‘precipitated. The alcohol added 
aids the precipitation, and the acetate solution prevents the precipitation of 
calcium salts or the formation of any free hydrochloric acid. ‘Tetra 


1 Chem. Centr.-Bl., Leipzig, 1887, S. 1560. 

2 Journ. Anat. and Physiol., London, 1874, vol. viii. p. 274. 

3 Ztschr. f. physiol. Chem., Strassburg, ASiisubGeie se Lo: 

4 « Physiological Chemistry,” London, 1893, vol. ii. p. 94, where a full account of 
these colour tests may be found. 

5 Ztschr. f. physiol. Chem., Strassburg, 1889, Bd. xiii. S.1. See also Sjoqvist, Skandin. 
Arch. f. Physiol., Leipzig, 1895, Bd. v. S. 277, ‘where a full history of this subject i is given, 
and a bibliography of over 150 memoirs on the subject. 


366 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


paper”! is used as an indicator; this turns a deep blue when the end of the 
reaction is reached. 

Leo’s method.2—In this method two determinations are made.—First, of 
the total acidity by titrating 10 c.c. of the gastric juice, after the addition of 
5 ec.c. of a concentrated solution of calcium chloride, with decinormal sodic 
hydrate solution, using litmus as an indicator. Secondly, the amount of 
acidity due to acid phosphates is similarly determined in a fresh portion of the 
gastric juice, after removing the acidity due to free acid by shaking up with 
finely-powdered calcium carbonate. The difference gives the amount of acidity 
due to free acid. 

Toepfer’s method ® consists in titrating 5-10 c.c. of the gastric juice against 
decinormal caustic soda with different indicators—(a@) with phenolphthalein, 
(b) with alizarin, (¢) with dimethylamido-azobenzol. The first titration 
gives the total acidity (consisting of free hydrochloric acid, hydrochloric acid 
combined with proteid, and organic acids) ; the second gives free hydrochloric 
acid, plus organic acids; the third, free hydrochloric acid only. Thus three 
equations are given for the determination of three unknown quantities. The 
method had been tested by Mohr with favourable results, and has the advan- 
tage of rapidity. 

Qualitative tests for lactic acid.—l. Uffelmann’s* test consists of an 
amethyst blue-coloured solution made by adding a trace of ferric chloride to a 
1 per cent. solution of carbolic acid. A trace of lactic acid added to this 
causes it to turn yellow; hydrochloric acid only decolorises it, and must be 
present in relatively large quantity to do so. The test is most safely applied 
by filtering the contents of the stomach, extracting the filtrate with ether, dis- 
tilling off the ether, extracting the residue with water, and adding this to a 
small quantity of the reagent. The test shows with 1 part of lactic acid in 
10,000. 2. A very dilute solution of ferric chloride, possessing only a trace of 
colour, is much deepened in colour on the addition of a mere trace of lactic 
acid. 


PANCREATIC JUICE. 


Normal pancreatic juice is difficult to obtain in quantity, on account 
of the inflammatory changes occurring in the gland, in consequence of the 
operation of inserting a cannula into the duct.? The fluid obtaimed from 
a fistula of the pancreatic duct in an animal is quite different, according 
to whether it is collected soon after the operation, during the first two 
or three hours, or after the lapse of a day or two. The fluid secreted 
during the first few hours is rich in solids, and is secreted very slowly ; 
that flowing from a permanent fistula is poor in solids, and is much more 
copious. The temporary secretion probably resembles the natural pan- 
creatic juice much more closely than the permanent secretion. 


1 Paper impregnated with paraphenylendiamine. For modifications of this method 
see Fawitsky, Virchow’s Archiv, 1891, Bd. exxiii. S. 292; von Jaksch, ‘ Klin. Diagnostik 
innerer Krankheiten,” 1892, Aufl. 3; Boas, Centralbl. f. klin. Med., Bonn, 1891, Bd. xii. 
S. 33; Kossler, Zéschr. f. physiol. Chem., Strassburg, 1893, Bd. xvii. S. 91. 

2 Centralbl. f. d. med. Wissensch., Berlin, 1889, Bd. xxvii. 8. 481. 

3 Zischr. f. physiol. Chem., Strassburg, 1894, Bd. xix. S. 104; Mohr, dbid., 8. 647. 

4 Ztschr. f. klin. Med., Berlin, 1884, Bd. viii. S. 392. 

5 The first to make a pancreatic fistula was de Graaf, 1664. For modern methods see 
Cl. Bernard, ‘‘ Lecons de physiologie expérimentale,” Paris, 1856, tome ii. p. 180; Bern- 
stein, Arb. a. d. physiol. Anst. zw Leipzig, 1869 ; Heidenhain, Hermann’s ‘‘ Handbuch,” 
Bd. v. (1), 8. 177; Rachford, Jowrn. Physiol., Cambridge and London, vol. xii. p. 80; 
Vassiliew, Arch. d. sc. biol., St. Pétersbourg, 1893, tome ii. p. 219; Fodera, Untersuch. 
2. Naturl. d. Mensch. uw. d. Thiere, 1896, Bd. xvi. S. 79; Lewin, Arch. f. d. ges. 
Physiol., Bonn, 1896, Bd. lxiii. For further details see article on ‘‘ Mechanism of Pan- 
creatic Secretion.” 


PANCREATIC JUICE. 367 


A temporary fistula should be made two or three hours after a meal, 
and the fluid collected during the next two or three hours. The greater 
number of such fistulae have been made on dogs. The fluid obtained is 
clear like water, but of a slimy, syrupy consistency ; ; 1t becomes still 
more viscid as it ‘cools, and undergoes at 0° C.a true coagulation, separat- 
ing into a gelatinous and a fluid portion. Its specific gravity is about 
1-030. Tt contains in suspension white corpuscles, which exhibit sluggish 
amoeboid movements. It is alkaline in reaction, the alkalinity being 
equal to 0:2-0-4 per cent. of NaHO, but the first few drops secreted may 
be acid. The alkalinity is commonly said to be due to carbonates 
and phosphates of sodium. The fluid is rich in proteid, froths on 
shaking, and on heating to 75° C. coagulates to a solid white mass. 
If kept warm for some time, its proteids become peptonised by the 
trypsin present with them. On dropping into water a precipitate is 
formed, which is soluble in dilute saline or acids. Alcohol gives 
an abundant flocculent precipitate, mostly soluble in water, and con- 
sisting of the proteid and enzymes. Leucine is present in traces, 
but not tyrosine. Similar secretions have been obtained from many 
other animals; the pancreatic juice of herbivora (rabbit, ox, and sheep) 
contains much less proteid than that of carnivora, but is in other 
respects similar. 

The permanent secretion sets im at a variable period, from a 
few hows to some days after the operation. It is very similar 
to the temporary secretion, except in containing much less organic 
matter, and in having in consequence a much lower specific gravity, 
1:010-1:011. 

Quantitative chemical composition.—The following table gives the 
results of analyses of both temporary and permanent secretions of dog’s 
pancreatic juice by C. Schmidt :'— 


1. ANALYSES OF TEMPORARY SECRETION, OBTAINED 2. ANALYSES OF SECRETION, OBTAINED 
DIRECTLY AFTER THE OPERATION. FROM PERMANENT FISTULE. 
a. b. a. b. c. 
| | 

Water . IS £ : 900°8 884-4 976°8 | 979°9 984°6 
Total solids . ; : 99:2 115°6 OB9, 20°1 15°4 

Organic matter . : 90°4 535 16°4 12°4 9-2 

Ash . 4 ; : 8°8 6°8 7-5 6°1 


3. COMPOSITION OF THE ASH (IN PARTS PER 1000 PARTS OF PANCREATIC JUICE). 


(a) From Temporary | (b) From Permanent 


Secretion. Secretion. 
Soda (Na,O) . : . : : ¢ : 0°58 3°31 
Sodium chloride. é : : ; : 7°35 2°50 
Potassium chloride . : : c 0:02 0°93 
Earthy phosphates with traces ofiron : 0°53 0-08 
Trisodic phosphate (Na,PO,) . : ; : ee 0-01 
Lime (CaO) and Magnesia (MgO) : : ; 0°32 0°01 


1 Quoted from Maly, Hermann’s ‘‘ Handbuch,” Bd. v. (2), S. 189. 


© 


Ww 


2 


368 CHEMISTR Y OF THE DIGESTIVE PROCESSES. 


These results show that, even in the same form of fistula, the amount of 
total solids and of organie matter is a very variable quantity. This is also 
shown by the results obtained by others. In the dog, Bernard found the 
total solids in temporary secretion, 86 to 100 per 1000 ; Tiedemann and 
Gmelin, 87 per 1000; Skrebitzki, 23 to 56 per 1000; in “the sheep, Tiede- 
mann and Gmelin, 36 to 52 per 1000; in the horse, Hoppe-Seyler, 8°88 
organic, 8°59 inorganic, per 1000; in the rabbit, Heidenhain, 17-6 per 1000 ; 
in the sheep, Heidenhain, 14:3 to 36-9 per 1000, 


Very few analyses of human pancreatic juice have been made, and 
it has never been obtained under quite normal conditions. Herter! 
obtained pancreatic juice, containing all three ferments, from an enlarged 
duct, due to carcinoma of the duodenum, which contained per 1000 parts, 
24-1 ‘parts of total solids, 17-9 parts of organic matter, 6°2 parts of ash. 


~Zawadski? has more recently published an account of human pancreatic 
4 “juice, obtained from a pancreatic fistula, remaining after removal of a 


pancreatic tumour. This sample resembled in composition those ob- 
tained from temporary fistule in animals, much more closely than 
Herter’s sample; it possessed a powerful digestive action, and probably 
was an almost normal secretion. It contained, per 1000 parts, 155°9 of 
total solids, 92 parts of proteids, 5-4 parts of inorganic-matter, the 
remainder being organic matter soluble im alcohol. 

Rate of secretion.—The figures given by various observers for the 
total quantity of pancreatic juice secreted in tw enty-four hours vary 
greatly, and it is impossible to state an average quantity with any 
approach to accuracy. Figures obtained from observations on permanent 
fistulee creatly exceed those obtained from temporary fistula. Bidder and 
Schmidt place the yield in the dog, at the rate of temporary secretion, at 
2°5 grms. per kilo. ‘of body weight per diem. At this rate a man of 70 
kilos. (154 lbs.) would secrete 175 grms. of pancreatic juice per diem. 


Succus ENTERICUS. 


The secretion of the small intestine may be obtained in animals, 
unmixed with the other digestive secretions, by one of two forms of fistula. 

The first form of fistula was introduced by Thiry,? and is made by 
cutting across the intestine at two places, 10 to 50 cms. apart, without 
interfering with the blood supply, restormg the continuity of the 
intestine, stitching up one end of the isolated piece, and uniting the 
other to the wound in the abdominal wall. The second form due to 
Vella,* is a modification in which both ends of the isolated piece of gut 
are left open and stitched to the abdominal wall one above the other.® 

Thiry describes the swecus entericus as a limpid, opalescent, light 
yellow-coloured fluid, strongly alkaline in reaction, and possessing a 
specific gravity of 1010. 

It contains proteid and mucin, and much carbonate, as shown 
by effervescence with dilute acids. According to Rohmann,° in the dog, 


1 Zischr. f. physiol. Chem., Strassburg, 1880, Bd. iv. S. 160. 

2 Centralbl. f. Physiol., Leipzig u. Wien, 1891, Bd. v. S. 179. 

3 Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1864, Bd. 1. Abth. 1, S. 77. 

4 Untersuch. z. Naturl. d. Mensch. u. d. Thiere, 1888, Bd. xiii. S. 40. For details as 
to establishing such fistule, see Gamgee, ‘‘ Physiological Chemistry,”’ vol. ii. pp. 406-408. 

5 For a full description of the methods of collecting intestinal juice, see article on 

‘* Mechanism of Intestinal Secretion.” 
6 Arch. f. d. ges. Physiol., Bonn, 1887, Bd. xli. S. 424. 


COMPOSITION OF BILE. 369 


the secretion of the upper part of the small intestine is scanty in 
quantity, shimy and clot-like, while in the lower part the secretion is 
much more fluid, and contains small clot-like masses: It contains 
4-5 parts per 1000 each of sodium chloride and sodium carbonate. 
Pregl? has recently obtained suceus entericus from a Vella fistula in the 
sheep, and estimated its alkalinity as equivalent to 0-454 per cent. of 
Na,CO,. The specific gravity of the fluid averaged 1:014. It contained 
proteid, and coagulated on standing. Thiry found in the dog, 2°2 to 2°8 of 
total solids, 0-7 to 1:2 of proteid, 0°7 to 0-9 of ash, per cent.; Leube, 0°8 to 2°7 
per cent. of proteid; Quincke, 1°54 to 1:45 per cent. of total solids; 
Frerichs, 2:27 per cent. of total solids; Gumilewski, 1°5 per cent. of 
total solids. 

Tubby and Manning? obtained pure human succus entericus from a 
piece of intestine, 34 in. in length, situated about 8 in. from the 
ileo-czecal valve, for a period of some months; the daily yield from this 
length of gut averaged 27 c.c. (19 to 35). Asa mean of thirty determina- 
tions, the specific gravity was found to be 1:0069 (1:0016 to 10162). The 
fluid was generally opalescent, and often had a brownish tint; it con- 
tained a few leucocytes and columnar cells, and was free from bacteria. 
It was invariably alkaline in reaction, and gave off carbonic acid gas on 
treatment with acids. It gave all the proteid reactions, and did not 
reduce Fehling’s solution or alter the colour of iodine solution. It con- 
tained lactates, as shown by darkening a dilute solution of ferric chloride, 
and giving Uffelmann’s test. It also contained much mucin. 


BILE. 


Action on foodstuffs.—Bile differs from the other digestive secre- 
tions in not possessing a marked chemical action on any of the organic 
foodstuffs. Bile alone is said to exert a diastatic action on starch,‘ but 
this is very slight and inconstant, and seems to be merely due to a slight 
absorption of diastatic enzymes;° on the other foodstuffs it has no 
chemical action whatever. Bile also increases the rate of action of 
pancreatic diastase ; but the bile salts alone have a similar effect, so that 
this accelerating action is not due to a diastatiec enzyme.® 

It has been shown that the presence of bile in the intestine 
has a favourable influence on the absorption of fat, and that when 
it is excluded, although the absorption of fat is not stopped, it be- 
comes very defective, and the same amount of fat cannot be taken 
up as when bile is present. This will be considered later under Fat 
Absorption. 

Chemical composition.—In its physical characteristics and chemical 
composition the bile is a variable mixture, not only in different classes of 
animals, but in the same individual. As secreted by the liver cells, and 
until it reaches the gall bladder, it is a clear limpid fluid, with a low 

1 Gumilewski, Arch. f. d. ges. Physiol., Bonn, 1886, Bd. xxxix. S. 565. 

2 Tbid., 1896, Bd. lxi. S. 359. 

3 Guy’s Hosp. Rep., London, 1891, vol. xlviii. p. 277. 

4 Ewald, ‘‘ Klinik d. Verdauungskrankheiten,” 1890, Bd. i. S. 150. 

° According to Kaufmann (Compt. rend. Soc. de. biol., Paris, 1890, tome xli. p. 600), 
the ferment occurs in the bile of the ox, pig, and sheep, in traces in that of the cat, and 
never in dog’s bile. Ellenberg and Hofmeister (Arch. f. wissensch. u. prakt. Thierh., 
Berlin, 1885, Bd. xi. S. 381, 393) found a diastatie ferment in horse, ox, and sheep bile, and 


occasionally in that of the dog and pig. In all cases, traces only of ferment are present. 
6 Martin and Williams, Proc. Roy. Soc. London, 1889, vol. xlv. p. 358. 


VOL. I.—24 


370 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


percentage of total solids and a correspondingly low specific gravity 
(1010). Im the gall bladder absorption of water takes place, and a 
mucin-like substance secreted by the epithelium of the gall bladder is 
added to it, so that it becomes viscid in consistency, the percentage of 
total solids is much increased, and the specific gravity rises (1030 to 1040). 
According to the time it stands in the gall bladder, these changes 
become more or less advanced, which accounts for much of the variation 
observed in the quantitative composition of different specimens of bile. 
The following table of analyses of dogs’ bile, (a) from the gall bladder 
and (0) freshly secreted from a fistula, illustrates this difference :? — 


In A HUNDRED PARTS BY WEIGHT OF 
(a) Bile from Gall Bladder. | () Freshly secreted Bile from 
I II I. II 
Mucin.. ‘ : ; : 0°454 0245 0°053 0170 
Alkaline taurocholates  . : 11°959 12°602 3°460 3°402 
Gholasterinste.) Sos. =. {newly NOMAD 0°133 0-074 0-049 
Lecithin . : ; : : 2°692 0°930 0°118 07121 
Fats : : : ; ; 2°841 0:083 0°335 0°239 
Soaps 5 . ‘ 5 ma 31155 0°104 0°127 0'110 
Organic matter insoluble in)\| 0°973 0-274 0442 0543 
alcohol : : : Sf 


Bile is an alkaline fluid containing on an average 0-2 per 1000 each of 
sodium carbonate and alkaline sodium phosphate. It has an intensely 
bitter taste, leaving a sweetish after-taste in the case of human or ox 
bile, but not in that of rabbit’s or pig’s bile. The bile of the ox and 
some other animals has a faint characteristic odour resembling musk, 
especially after warming. The colour is very variable : in carnivora it 
is usually golden-yellow ; in herbivora a grass-green; but these colours 
are not constant, and vary with the amount of oxidation of the bile 
pigments; the two chief colours are often mixed with brown, giving 
intermediate shades of yellowish and greenish brown. Human bile, 
when observed in a healthy condition and immediately after death, is 
often green, occasionally golden-yellow in colour. 

Bile contains no coagulable proteid, and remains clear on boiling; it 
can also be diluted with water without any turbidity arising. In human 
bile true mucin is present,® but the substance which gives viscidity to ox 


1 Accompanied by a selective absorption of inorganic constituents, so that the percentage 
of chlorides in gall bladder bile is even less than that in liver bile (Hammarsten, Joc. cit., 
sub. 15). 

2 Hoppe-Seyler, ‘‘ Lehrbuch der Physiol. Chem.,” Berlin, 1881, S. 302. See also 
Hammarsten, Nova Acta. Reg. Soc. Sc. Upsala, 1893, Ser. 3, vol. xvi.; Jahresb. wi. d. 
Fortschr. d. Thier-Chem., Wiesbaden, 1893, Bd. xxiii. S. 331. 

3’ Hammarsten, Nova Acta Reg. Soc. Sc. Upsala, 1893, Ser. 3, vol. xvi.; Jahresb. ti. d. 
Fortschr. d, Thier-Chem., Wiesbaden, 1893, Bd. xxiii, 8S. 333, 


SPECIFIC CONSTITUENTS OF BILE. 00 


bile has been shown not to be mucin but a nucleo-albumin. Other 
substances present in bile are—(1) the alkaline salts of certain organic 
acids known as the bile acids; (2) the bile pigments; (3) traces of 
lecithin, cholesterin, soaps, and fats ; (4) mineral salts. 

Both the total and relative amount of each of these several con- 
stituents or group of constituents is very variable, as is shown by the 
following table of analyses of human bile made by different observers. 
The numbers indicate parts by weight contained in 1000 parts by 
weight of bile :+— 


FRESH BILE FROM GALL BLADDER. BILE FROM FISTUL. 
Frerichs.2 y. Gorup-Besanez.3 Secu. aes Al ‘aud eae Wiel ey 
Water - | 860°0) 859°2| 822°7| 898-1] 977°4 | 987°16 | 985-77 | 981°98 | 988-08 | 984-79 
Total solids | 1400} 140°8} 177:3| 101-9) 22°6 | 12°84) 14:23] 18-02] 11:92] 15-27 
Sodium gly- | 
cocholate | ("| 1°65 A) eae 
102°2} 91:4) 107°9| 56:5) 10-1 6-28 3°49 
Sodium taur- | \| 0-55 0-09) 0-49 
ocholate 
| 
Cholesterin 16 2°6 | 0°56 0:45| 0°53 | 
Lecithin . ae _ - 47°3| 30°9 0°05 0-38} 0-99 se as ee 
Batsis a: y 39) 9-9 | | 0-12! 0-09 
1:50 
Soaps. 0:97| 0-15 
| Mucin pig- | 
ment, epi- Gyre : 2. AG : : we ; 
| thelium, if 26°6| 29°8) 22:71) 145) 2°3 1-48} 1°72) - 1-30 [ 
ete. 709 |- 
Tnorganic 65 Tile 108 63} 85 CAF (45 L 7:58 | 6°41 
salts 
| 


The samples of bile from the gall bladder, analysed by Frerichs and by vy. 
Gorup-Besanez, were obtained immediately after death from healthy subjects, 
the others were from biliary fistulae of long standing. 


Specific Constituents of Bile. 


Nucleo-proteid of bile.—Landwehr ® first drew attention to the fact 
that the percentage composition of the mucin of bile was different from 
that of other mucins, and that no reducing sugar was formed on heating 
it with a mineral acid, but attempted to explain this by assuming that 


1 Extracted partially from Bunge, ‘‘ Lehrbuch der physiol. und pathol. Chemie,” 
Leipzig, 1894, S. 192; and partially from Noel Paton and Balfour, Zep. Lab. Roy. Coll 
Phys., Edin., 1891, vol. iii, poe 

2 Hannover. Ann. f. d. ges. Heilk., 1845, N.F. Bd. v. 8. 42. 

3 Prager. Vrtljschr. f. prakt. Pharmakol., 1851, Bd. iii. S. 86. 

4 Ber. d. deutsch. chem. Gesellsch., Berlin, 1873, Bd. vi. S. 1026. 

> Journ. Physiol., Cambridge and London, 1884, vol. v. p. 116. 

° Tbid., 1889, vol. x. p- 213. 

7 Proc. ’ Roy. Soc. London, 1890, vol. xlvii. p. 499. 

8 Loc. cit. 

® Ztschr. f. physiol. Chem., Strassburg, 1881, Bd. vy. S. 371. 


372 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


a glycogen-like substance was present in the other mucins, which, on 
boiling with a mineral acid, formed a reducing sugar ; this substance he 
supposed to be absent in bile mucin, and hence no reducing sugar was 
formed on heating it with a dilute mineral acid. 

Paijkull? afterwards proved that the mucin-like substance which 
gives bile its viscidity really belongs to the nucleo-proteids. If bile be 
precipitated with dilute acetic acid, the presence of the bile salts 
prevents the precipitate from redissolving in excess, and so causes it to 
simulate a mucin; but if the bile salts are removed by dialysing, or by 
precipitating the substance with alcohol, centrifugalismg and quickly 
redissolving in water, the precipitate readily redissolves in excess of 
acetic acid, and in this respect resembles a nucleo-proteid and not a 
mucin. Also, when the substance is precipitated by, and just redissolved 
in, dilute hydrochloric acid, and then subjected to peptic digestion, a 
substance is precipitated, which by its percentage of phosphorus can be 
recognised as similar to the nuclein yielded under like conditions by 
nucleo-proteids. These facts, together with the much higher percentage 
of nitrogen (14 to 16 per cent.) than mucin which it contains, and its 
failing to yield a reducing sugar on boiling with dilute mineral acids, 
show the substance to be a nucleo-proteid and not a mucin. The quantity 
of this substance present in bile is very variable but always small, 
amounting in ox bile to about one per thousand? 

The bile salts.—There are found in bile the salts of a number of 
organic acids of complicated structure, which are closely allied to one 
another ; these salts are collectively called the bile salts. They are not 
found in health in appreciable quantity elsewhere than in the bile, and 
usually occur as sodium salts, except in the bile of some sea fishes, in 
which they are present as potassium salts. 

Since bile is so easily obtainable in quantity, it is not surprising that 
it should early have attracted the notice of the physiological chemist. 
Thénard, in 1809, working with ox bile, was the first to obtain any 
scientific knowledge of the bile acids. He distinguished two com- 
ponents in bile, one precipitated by acetate of lead, which he called 
bile resin, and a soluble part, which he named pieromel. He seems 
to have roughly separated in an impure condition those two most 
commonly occurring bile acids, which we know to-day as glycocholic and 
taurocholic acid, by a method not widely differing from that most used 
at the present time. He precipitated bile with neutral and basic acetates 
of lead, and then extracted the precipitate with nitric acid ; the insoluble 
part left behind, his resin of bile, was impure glycocholic acid. The filtrate 
he reprecipitated with excess of acetate of lead, collected the precipitate, 
and decomposed it by a current of sulphuretted hydrogen, thus obtaining 
his picromel, which must have corresponded to impure taurocholic acid. 

In 1826, Gmelin published a memoir? in which is described a large 
number of bile constituents; amongst them, one corresponding to 
glycocholic acid, which he obtained in a crystalline form; and another 
substance, taurine, of which he was the discoverer, although he wrongly 
supposed that it existed ready formed in the bile. The next important 
advance was made by Demarcay,‘ who obtained a substance (Choleinséure) 
which yielded, on heating with acids, taurine and a resinous substance, 


* Ztschr. f. physiol. Chem., Strassburg, 1888, Bd. xii. S. 196. 2 Paijkull, Zoc. cit. 
3 “Die Verdauung nach Versuchen.” 
4 Ann. d. Chem., Leipzig, 1838, Bd. xxvii. S. 270. 


LHE BILE SALTS. 373 


and, on treatment with alkalies, ammonia and a non-nitrogenous acid, 
corresponding to what to-day is called cholalic acid. 

In 1844, Plattner! succeeded in obtaining the bile salts in a 
erystalline form, and so laid a sure foundation for all succeeding work on 
the isolation and study of the bile acids. He also showed, by boiling 
this crystalline product with acid, that taurin is a decomposition product 
and does not exist as such in bile. Redtenbacher? previously to this had 
shown that this body contains sulphur, and established its formula as 
C,H,NSO,. Plattner* afterwards discovered a simpler method of 
obtaining the mixed bile salts in crystalline form. He concentrated the 
bile without decolorising, and then added an excess of alcohol, warmed, 
and after some time filtered and added ether, till a brown sticky 
precipitate began to fall; this was allowed to settle, and the clear fluid 
decanted off, cooled, and treated with more ether from time to time. 
The bile salts alone being the only constituents which are soluble in 
water and alcohol, and insoluble in ether, are slowly thrown out of 
solution ; and on standing for some days or weeks in the cold, under the 
alcoholic ethereal mother-liquid, form themselves into ball-shaped masses, 
or starlike clusters of fine needles, which increase in size on standing. 
This crystallme mass is known as “ Plattner’s crystallised bile.” The 
erystals are dried between filter-paper, washed with alcohol, containing 1 
in 10 of ether, purified by recrystallisation, and dried over sulphuric acid. 

This discovery of Plattner’s paved the way for the classical researches 
of Strecker, to whom we owe the greater part of any exact knowledge we 
have of the bile acids. _ Strecker * first showed that “ Plattner’s crystallised 
bile” consists of a mixture of the sodium salts of two acids, which are so 
related to each other that they yield, on boiling with acids, a common 
non-nitrogenous constituent, cholalic acid, and a nitrogenous constituent, 


-which in both cases is an amido-acid. One of these amido-acids is 


glycocoll or amidoacetic-acid, the other taurine or amidoethylsulphonic- 
acid. Of the two bile acids the one which yields glycocoll and cholalic 
acid is called glycocholic acid, while the other, which yields taurime and 
cholalic acid, is named taurocholic acid. 

Cholic or cholalic acid is not, however, the only basis of the different 
varieties of bile acids; other acids closely allied to it in percentage com- 
position, but quite distinct from it, have been isolated. In ox bile about 
a third part of the cholalic acid is replaced by an acid called choleic 
acid.® In human bile an acid called fellic acid® has been described as 
occurring along with cholalic and choleic acids; and modified cholalic 
acids are present in the hyoglycocholic acid of pig’s bile and the cheno- 
taurocholic acid of goose bile. None of these substitutes of cholalic 
acid occur free in bile, but always combined with glycocoll or taurine 
to form modified glycocholic or taurocholic acids; they are all soluble 
with difficulty in water and ether, and easily soluble in alcohol.” 


1 Ann. d. Chem., Leipzig, 1844, Bd. li. S. 105. ? Ibid., 1846, Bd. lvii. S. 170. 

3 Journ. f. prakt. Chem., Leipzig, 1847, Bd. xi. S. 129. 

4 Ann. d. Chem., Leipzig, 1848, Bd. lxy. 8. 1; 1848, Bd. Ixvii. S. 1 ; 1849, Bd. Ixx. 
S. 149. 

° Latschinoff, Ber. d. deutsch. chem. Geselisch., Berlin, 1885, Bd. xviii. S. 3039 ; 1886, 
Bd. xix. S. 1140; 1887, Bd. xx. S. 1043. 

§ Fellinsiure of Schotten, Ztschr. f. physiol. Chem., Strassburg, 1887, Bd. xi. S. 268. See 
also Lassar-Cohn, Ber. d. deutsch. chem. Gesellsch., Berlin, 1894, Bd. xxvii. S. 1339. 

7 Hammarsten’s ‘‘ Lehrbuch,” 1895, S. 198. He describes a third variety of bile acid, 
found in shark’s bile, which is rich in sulphur, and from which boiling with hydrochloric 
acid splits off sulphuric acid. 


374 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


The alkaline salts of the bile acids are soluble in water and alcohol, 
but insoluble in ether, and these solubilities form the basis of Plattner’s 
method of separating them from the other biliary constituents. This 
is best done by mixing the bile with freshly-heated animal charcoal, 
evaporating to complete dryness, and then extracting with absolute 
alcohol, which takes up the bile salts along with cholesterin and traces 
of lecithin, fats, and soaps; but, on addition of excess of ether, only the 
bile salts are thrown out of solution. 

The relative amount of each of the bile acids present in bile varies 
within wide limits. In the bile of carnivora, glycocholate of sodium is 
present in very small quantity; for example, the bile salts of dog’s bile 
consist exclusively of taurocholate of sodium,’ while in most herbivora 
the glycocholate is usually present in greater quantity than the tauro- 
cholate ; to this rule the goat and sheep are said to be exceptions. 

In human bile most of the cholalic acid is combined with glycocoll, 
occasionally the whole of it.2 Hammarsten’s* analysis of the mixed bile 
salts of healthy human bile gave 13:1 per cent. taurocholic acid, 86°9 
per cent. glycocholie acid. Since glycocholic acid is sulphur-free, and 
the percentage in taurocholic acid is known, the relative amount of the 
two acids may be determined from the percentage of sulphur in a 
preparation of Plattner’s crystallised bile, obtained from any given sample 
of bile. 

The isolation of each of the bile acids from a mixture of their 
salts is usually a lengthy and difficult process, especially in the case of 
taurocholic acid, which can only with great difficulty be freed from 
glycocholic acid, so that taurocholic acid is usually prepared from dog’s 
bile, while glycocholic acid is prepared from ox bile. 

Both free acids behave like their sodium salts in being soluble in 
alcohol and insoluble in ether, but differ in that taurocholic acid is easily 
soluble in water, while glycocholie acid is soluble with great difficulty. 
On this property is based the simplest method of obtaiming pure 
glycocholic acid, that of Hiifner;+ unfortunately, the presence of 
taurocholic acid confers solubility on the glycocholie acid, so that the 
method often fails when too much taurocholate is present in the sample 
of bile experimented upon. 


The method consists in adding to fresh ox bile a few drops of hydrochloric 
acid, and filtering from the precipitated pseudo-mucin. To 100 cc. of this 
filtrate 5 c.c. of concentrated hydrochloric acid and 30 e.c. of ether are added. 
The hydrochloric acid sets free both bile acids, and the glycocholic acid is 
precipitated in crystalline form (unless too much taurocholiec acid be present), 
either immediately, or on standing some hours in the cold. The ether added 
aids in the production of this crystalline precipitate, which is next washed 
with acidulated water saturated with ether, and finally recrystallised from 
boiling water. 

Marshall® tested Hiifner’s method with 543 samples of ox bile, and 
obtained a precipitation in 121 cases. A similar method was employed by 
Strecker,® using a watery solution of crystallised bile instead of fresh bile. 


1 Strecker, Ann. d. Chem., Leipzig, 1849, Bd. lxx. S. 178; Hoppe-Seyler, Journ. f. 
prakt. Chem., Leipzig, 1863, Bd. 1xxxix. S. 288. 

2 Jacobson, Ber. d. deutsch. chem. Gesclisch., Berlin, 1873, Bd. vi. S. 1028. 

8 Schmidt's Jahrb., Leipzig, 1879, Bd. clxxxi. S. 5. 

4 Jahres. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1874, Bd. iv. S. 301. 

© Zischr. f. physiol. Chem., Strassburg, 1887, Bd. xi. S. 233. 

5 Ann. d. Chem., Leipzig, 1848, Bd. Ixv. S. 1. 


g 


THE BILE ACIDS. 375 


The different solubilities of the lead salts of the two acids provides 
another means of separating glycocholic acid; the separation of pure 
taurocholic acid from the mixture by this method is more difficult. 


Glycocholate of lead is thrown out of solution on the addition of neutral 
acetate of lead to a solution of a mixture of the bile salts ; the remainder of 
the glycocholate and all the taurocholate are thrown down on the addition of 
ammonia or of basic acetate of lead to the filtrate. 

Fresh ox bile is treated with alcohol to precipitate the pseudo-mucin. 
The alcohol is evaporated off, and neutral acetate of lead added as long as a 
precipitate forms ; this precipitate is collected and decomposed by warming 
with a solution of sodium carbonate, whereby sodium glycocholate is formed ; 
the mixture is next evaporated to dryness, and extracted with alcohol, in which 
the sodium glycocholate dissolves. This alcoholic solution is filtered, the 
filtrate is evaporated to dryness, and the residue is dissolved in water. The 
watery solution of sodium glycocholate so obtained is decolorised with animal 
charcoal, and the glycocholic acid thrown out of solution by adding a mineral 
acid. Finally, it can be recrystallised, either from boiling water, or by the 
addition of ether to its alcoholic solution. Taurocholic acid can be obtained 
from the filtrate from neutral acetate of lead, by fractional precipitation with 
basic acetate of lead, as the remaining glycocholate unprecipitated by the 
neutral acetate is precipitated by the portion of basic acetate first added.! 
Basic acetate of lead is stirred into the filtrate from the neutral acetate, until 
the precipitate commences to gather into a sticky mass, when the addition is 
discontinued, and the solution decanted off from the precipitate. More basic 
acetate solution is now added, and throws down a plastic mass, consisting of 
fairly pure taurocholate of lead. This precipitate is dissolved in boiling 
alcohol, filtered warm into water, and the resulting reprecipitated mass, after 
being purified by kneading, is dried, dissolved in a small quantity of alcohol, 
decomposed with sulphuretted hydrogen, filtered from lead sulphide, and 
dried at first in the air, afterwards in a vacuum over sulphuric acid. 


Taurocholic acid is, however, best prepared from dog’s bile, as 
described by Parke.? 


The bile is evaporated down, extracted with alcohol, decolorised with 
animal charcoal, evaporated to dryness, dissolved in absolute alcohol, and 
treated with excess of ether. After some time the crystalline precipitate of 
sodium taurocholate so obtained is dissolved in water, and the solutions 
precipitated with acetate of lead and ammonia. The precipitate is collected, 
washed, suspended in alcohol, or dissolved therein by boiling, and decomposed 
by sulphuretted hydrogen. The filtrate from sulphide of lead is evaporated 
to a small volume, and mixed with excess of ether, when the taurocholic acid 
is precipitated as a syrup, in which, after some time, small crystals appear. 
These are in the form of fine needles which deliquesce in the air. 


Glycocholic acid (C,,H,,NO,) is a monobasic acid, crystallising in 
long fine needles, which fell together into a light, voluminous mass 
when first formed from a solution, and on drying form a loose, snowy 
white mass with a silky glance. These crystals melt at 100° C., losing 
water in so doing and forming glycocholonic acid; they are very 
sparingly soluble in cold water (1 in 300), somewhat more soluble in 
boiling water (1 in 120), and so can easily be recrystallised from hot 
water; they are easily soluble in alcohol and in acetic acid, but soluble 
in ether with great difticulty. Glycocholic acid and its salts in solution 


1 Lieberkiihn, Jahresb. ii. d. Fortschr. d. ges. Med., Erlangen, 1852, Bd. i. S. 115. 
2 Hoppe-Seyler’s Med.-chem. Untersuch., Berlin, 8. 160. 


376 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


rotate the plane of polarised light to the right; in alcoholic solution the 
specific rotatory power for the acid is +20°-0, for the sodium salt +25°°7 
(Hoppe-Seyler). The salts of the alkalies and alkaline earths are 
soluble both in water and in alcohol, those of the heavy metals are 
mostly much more insoluble in water, so that addition of salts of such 
metals as lead, copper, iron, or silver, causes precipitation of the corre- 
sponding glycocholates. The lead salt is soluble in rectified spirit, from 
which it is precipitated on the addition of water. The acid and its 
salts possess a peculiar taste, sweetish at first, but afterwards intensely 
bitter. 

Taurocholie acid (C,,H,;NSO,), also a monobasic acid, is crystallisable 
with difficulty, forming fine deliquescent needles. It is very easily soluble 
in water, and also possesses the power of carrying glycocholic acid into 
solution when that acid is simultaneously present. It is exceedingly 
soluble in alcohol, but insoluble in ether. In solution it possesses a 
bitter-sweet taste, which is shared by its alkaline salts. The salts are 
generally easily soluble in water, and a solution of an alkaline tauro- 
cholate, unlike that of a glycocholate, is not precipitated by the usual 
salts of the heavy metals, such as copper sulphate, silver nitrate, or 
neutral lead acetate ; basic lead acetate does, however, precipitate it, and 
the compound so formed is soluble in boiling alcohol. 

Taurocholic acid is not nearly so stable a compound as glycocholic 
acid, it decomposes on boiling in aqueous solution, or in evaporating to 
dryness; hence the dry pure acid has never been prepared or analysed, 
and its formula has been deduced from analogy with glycocholic acid, 
and from analyses of its more stable salts. Its solutions rotate the 
plane of polarisation to the right, like glycocholie acid. The specific 
rotation of the alcoholic solution of. the sodium salt is +24°°5. Potassium 
taurocholate occurs in the bile of many fishes; it possesses the peculiar 
property of being completely thrown out of solution in water by the 
addition of solution of caustic potash, and so may be prepared by adding 
this reagent to an aqueous solution of an alkaline taurocholate. 
Analyses of this salt by Strecker! established its formula as 
C.;H,,KNSO,, and analyses of the sodium salt gave a corresponding 
result, from which it follows that the formula of taurocholic acid 
itself is C,,H,,NSO,. 


Hyoglycocholic acid is an acid found in pig’s bile,? which yields on decom- 
position glycocoll, like ordinary glycocholic acid, but an acid differing in 
composition and behaviour from ordinary cholalic acid (C,,H,,O;), and 
ealled hyocholalic acid (C,;H,,O0,). This acid differs from cholalie acid in not 
being so easily crystallisable, and in having a difficultly soluble barium salt. 
Severin Jolin ® states that pig’s bile contains, as principal bile salts, the sodium 
salts of two different hyoglycocholic acids, each of which yields on decomposi- 
tion glycocoll and a hyocholalic acid (a and 8). The two hyoglycocholic acids 
are distinguished by the different solubilities of their sodium salts in neutral 
salt solutions. The @-salt is present in much greater quantity; but the 
distinguishing character of pig’s bile, that it is precipitated by saturation with 
various neutral salts, is not due to the fB- but to the a-hyoglycocholic acid. 


1 Loc. cit. 

* Strecker and Grundelach, Ann. d. Chem., Leipzig, 1847-9, Bd. lxii. S. 205; Bd. Ixx. 
S. 179. 

* Zischr. f. physiol. Chem., Strassburg, 1887-9, Bd. xi. S. 417; Bd. xii. S. 512; 
Bd. xiii. S. 205. 


THE BILE ACIDS. 377 


The two hyocholalic acids show analogous differences to the two hyoglycocholic 
acids. The formula of a-hyoglycocholie acid is Cy,;H,,NO;, that of B-hyo- 
glycocholic acid is C,,H,,NO.. 

Taurochenocholic acid,! the principal bile acid of goose bile, has the 
formula C,,H,,NSO,, has not been crystallised, and is soluble in water and 
alcohol. From this acid Heintz and Wislicenus? prepared chenocholie acid 
(C,,H,,0,); this is itself crystallisable with difficulty, but yields a barium salt, 
which is insoluble in water and can easily be obtained in a crystalline form. 


Pettenkofer’s test for bile acids.s—When bile is gently warmed with 
concentrated sulphuric acid and cane-sugar, a beautiful purple or 
purplish-red colour develops, becoming deeper on standing. The colour 
is due to an interaction between the bile salts, or cholalic acid, and a 
substance called furfurol or furfuraldehyde developed by the action of 
the strong sulphuric acid on the cane-sugar;* hence the test may 
be more satisfactorily carried out where only traces of bile salts are 
suspected, by using a solution of furfurol (1 per 1000) instead of cane- 
sugar. 


To carry out the test in the ordinary manner, add to a drop or two of the 
bile, or fluid suspected of containing bile acids, a drop of strong sulphuric 
acid, taking care that any great rise in temperature does not occur ; spread the 
mixture out in a thin film in a porcelain capsule, and either add a drop of a 
10 per cent. solution or a small crystal of cane-sugar ; if the violet colour does 
not appear at once, warm very gently. To carry out the test with furfurol, one 
drop of a solution of furfurol (1 per 1000) is added to 1 cc. of an alcoholic 
solution of bile salts, and 1 c.c. of concentrated sulphuric acid is added 
cautiously to this, so as not to overheat. In this manner ;\,—3'5 of a milligramme 


of cholalic acid may be detected.° 


The test with sugar may be easily spoiled by overheating or when 
too much sugar is used, which favours carbonisation. The presence of 
sulphurous acids or nitrous fumes in the sulphuric acid is also unfavour- 
able to the reaction. Strong phosphoric acid may be used instead of 
sulphuric acid. 

Many other substances give a similar reaction. Pettenkofer himself 
was aware that proteids gave a similar colour, though much less easily. 
By subsequent observers © a large number of substances giving colour re- 
actions with furfurol have been described; amongst these many phenols 
and aromatic bases are included, some of which are also found in 
the urine. v. Udranszky’ gives a list of over forty substances which 
give colour reactions with furfurol, but none except a-naphthol show 
the reaction with the same delicacy as the bile salts. That the 
coloured substance so produced is not in all cases the same, is shown 
by the fact that some possess no absorption spectrum, and that the 
spectra of the others differ from one another. In this way the 
spectrum of the colour given by the bile salts may be distinguished 


1 Marsson, Arch. d. Pharm., Bd. lvii. S. 138. 

2 Ann. d. Phys. u. Chem., Leipzig, 1859, Bd. eviii. S. 547. 

3 Ann. d. Chem., Leipzig, 1844, Bd. lii. S. 90. 

4 Mylius, Ztschr. f. physiol. Chem., Strassburg, 1887, Bd. xi. S. 492. 

5 vy. Udranszky, ibid., 1888, Bd. xii. S. 355. 

6 Baeyer, Ber. d. deutsch. chem. Gesellsch., Berlin, 1872, Bd. v. S. 26; Stenhouse, 
Ann. d, Chem., Leipzig, 1870, Bd. elvi. S. 197 ; Schiff, ibid., Bd. cci. S. 355. 

7 Loc. cit. Drechsel, Journ. f. prakt. Chem., Leipzig, Bd. xxvii. S. 424. 


378 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


from the others by two bands, one between the solar lines D and E 
near to E, the other at F. 


The bile salts produce great slowing of the heart’s beat, which may be used 
as a physiological test for them in confirmation of Pettenkofer’s reaction. In 
a curarised frog the heart is exposed, the pericardium removed, and the action 
of the vagus paralysed by atropine; on now adding a drop of a solution of a 
bile salt, the rhythm of the heart is greatly slowed.? 


Cleavage products of the bile acids.—All the bile acids, under the 
action of hydrating agents, split up into two components, of which one 
is always either glycocoll or tauri, and the other a non-nitrogenous 
monobasic acid which may be cholalic acid or one of several allied acids. 

Glycocoll and taurin are nitrogenous bodies, belonging to that class 
of substances called amido-acids, 7.c. organic acids, in which one or more 
hydrogen atoms are replaced by the group amidogen (NH,). Both these 
amido-acids are probably formed by the breaking up of proteids, or 
their allies the albuminoids. 


The process of hydration can be carried out directly from bile, by heating 
with hydrochloric acid, in a flask attached to a reversed condenser. Taurin 
and hydrochlorate of glycocoll are formed, and the free cholalic acids, which 
slowly lose water and pass into the form of their anhydrides (the dyslysins, 
p. 382); these being insoluble are precipitated. As soon as the reaction is 
completed, as shown by the failure of Pettenkofer’s test, the flask is allowed 
to cool and the dyslysins filtered off. The filtrate, which contains the 
amido-acids, is strongly concentrated, and, while still warm, decanted from the 
sodium chloride which has crystallised out. It is next evaporated to com- 
plete dryness and treated with absolute alcohol, which takes up the glycocoll 
hydrochlorate and leaves the taurin behind. The residue is dissolved in as 
small a quantity as possible of warm water, and filtered while warm; to 
this filtrate a little alcohol is added, and, on slowly cooling, crystals of taurin 
are formed. 

The alcohol is evaporated from the alcoholic extract containing the glycocoll 
hydrochlorate, and water is added; to the watery solution, hydrate of lead is 
added, when insoluble lead chloride and a soluble lead compound of glycocoll 
are formed. The latter is separated in solution by filtration ; into the solution 
a stream of sulphuretted hydrogen is passed, the lead sulphide is filtered off, 
and the filtrate is concentrated, until, on cooling, free glycocoll crystallises out. 

The free cholalic acids* can be recovered from the dyslysins formed in 
the first step of the above process. The dyslysins are removed from the 
filter, and boiled with dilute alkali, when they take up water, and, combining 
with some of the alkali, are converted into soluble alkaline cholalates. On 
acidifying with hydrochloric acid, and evaporating to dryness, the cholalic 
acids can be extracted with a small quantity of hot alcohol, from which they 
crystallise on cooling, or on the addition of excess of ether. 


Glycocoll, glycocine, or glycine, is amido-acetic acid (NH,.CH?.COOH). 
Besides occurring combined with cholalic acid, as glycocholic acid in the 
bile, it is found in the urine of certain animals and occasionally in man, 
combined with benzoic acid, to form hippuric acid, and is formed as an 
end hydration product from gelatine and similar substances. 


1 Koschlakoff and Bogomoloff, Centralbl. f. d. med. Wissensch., Berlin, 1868, Bd. vi.* 
S. 529. In this paper four bands are described. Bogomoloff, ibid., 1869, Bd. vii. S. 529 ; 
Schenck, Jahres. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1872, Bd. ii. S. 232. 

* Mackay, Arch. f. exper. Path. u. Pharmakol., Leipzig, 1885, Bd. xix. 8. 279. 

* The term “‘cholalic acids” is used to signify cholalic acid and its allies. 


CLEAVAGE PRODUCTS OF THE BILE ACIDS. 379 


It crystallises in colourless rhombohedra, or in four-sided prisms, which have 
a sweet taste and dissolve easily in cold water (1 in 4°83); in alcohol and ether 
they are insoluble. Glycocoll, like other amido-acids, can act chemically, either 
as a base or an acid in forming compounds with acids and bases respectively. 
As a type of these combinations with bases, the copper compound may be 
taken. When freshly precipitated cupric hydrate is added to a warm con- 
centrated solution of glycocoll, it dissolves to form a deep blue solution, which 
is not reduced on boiling ; on cooling this solution, or on adding alcohol and 
allowing to stand, fine dark blue needles crystallise out of the composition 
(NH,.CH,.CO,),Cu,H,O. Glycocoll has been obtained synthetically by the 
action of ammonia on monochloracetic acid thus :— 


NH, + CH,.CI—COOH = CH,.(NH,)—COOH + HCl. 


Taurine is amido-isethionic acid, also called amido-oxyethylsulphonic 
acid (NH,.C,H,.SO,OH).! It occurs in the body, apart from the bile, only 
in minute and inconstant traces; it has been stated to occur in the lungs 
and kidneys of oxen, in some of the organs of cold-blooded animals, and 
in inconstant traces, probably due to the decomposition of taurocholates, 
in the intestine. The presence of sulphur in its molecule shows it to be 
formed from proteids in the body; but the intermediate steps in its 
formation are unknown. 


Taurine is very easily crystallised, and forms large colourless prismatic 
prisms with a glassy glance,? without any taste, and gritty between the teeth, 
neutral in reaction and very stable, not being altered by a temperature of 
240 °C. ; heated above this temperature they melt and decompose in so doing. 
It is much less soluble in cold water than glycocoll, but still easily soluble 
(1 in 15:5), and still more so in hot water ; in alcohol and ether it is insoluble. 
It is soluble in concentrated sulphuric and nitric acids without decomposition, 
and the latter acid may even be boiled off, leaving it unaffected ; neither is it 
affected by boiling with aqua regia. To alkalies also it is much more stable 
than glycocoll; it is not affected by weak alkalies, and only by continued 
boiling in strong alkaline solution is slowly broken up into ammonia, acetic, 
and sulphurous acids; so that it is one of the most stable of the organic 
compounds found in the body. Taurine is also a much more neutral substance 
in its chemical behaviour than glycocoll ; it does not combine at all with acids, 
and its affinity for bases is very feeble. An amorphous mercury compound is 
however obtained by boiling a solution of taurine with freshly-precipitated 
mercuric oxide.* 


The constitution of taurine is shown by its synthesis from chlorethyl- 
sulphonic acid by the action of ammonia.* 


C,H,Cl C,H,NH, 
4+ NH,=80,7 


S0,7 
Nou 


+ NH,Cl 
“\OH 4 

This synthesis, as well as the fact that taurine is not saponified by 
dilute alkalies, shows that taurine is not an ester but a sulphonic 
derivative; that is, that the sulphur atom is united directly to carbon, 
and not indirectly by oxygen. Taurine may also be obtained by heating 


1 The amido-oxyethy] radicle is directly united to sulphur in the molecule. 

2 Gmelin, ‘‘ Verdauung nach Versuchen,” S. 60. 

3 Lang, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1876, Bd. vi. S. 74. 
+ Kolbe, Ann. d. Chem., Leipzig, 1862, Bd. exxii. S. 33. 


380 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


the ammonium salt of oxyethylsulphonic acid to 250° C., when a 
molecular rearrangement takes place, thus: 


C,H,.OH / OHNE, 
S00 =O, +H,0 
NoNH, \OH 


Cholalice acid is the usual partner with glycocoll or taurime in the 
formation of the bile acids; it is also found in the intestinal contents, 
and sometimes, in cases of jaundice, in the urine. One method of 
obtaining it has already been incidentally mentioned, but it is better 
prepared by the following method :1— 


Ox bile is boiled for about twenty-four hours with the fifth part of its 
volume of 30 per cent. caustic soda solution, the water being replaced as it is 
removed by evaporation. The solution is then saturated with carbon-dioxide 
gas, and evaporated almost to dryness. The residue is extracted with 96 per 
cent. alcohol, and the extract, diluted so that it does not contain above 20 
per cent. of alcohol, is completely precipitated with a solution of barium chloride. 
The precipitate, which consists of impure barium choleate, is filtered off, and 
cholalic acid is precipitated from the filtrate by the addition of hydrochloric acid. 
The acid slowly becomes crystalline on standing, when it is separated and puri- 
fied by repeated recrystallisation from alcohol. Cholalic acid occurs in many 
crystalline forms.2. Anhydrous crystals forming flat-ended 4- to 6-sided prisms, 
may be obtained by dissolving the amorphous form of the acid, produced by 
drying one of the other crystalline forms, in ether and allowing the solution 
to crystallise out. 

From strong alcohol the acid crystallises, on the addition of a very little 
water, in octohedra and tetrahedra, belonging to the orthorhombic system, and 
containing two and a half molecules of water of crystallisation ; from dilute alcohol 
it crystallises in fine shining flat needles or plates, containing only one molecule 
of water of crystallisation.? It also erystallises in large rhombic tetrahedra, or 
octohedra containing one molecule of alcohol. Pure anhydrous cholalie acid 
melts at 194° to 195° to a colourless liquid; and on heating above this temperature, 
loses water and is converted into its anhydride or dyslysin ; on further heating, 
it loses more water and yields a viscid yellow or yellow-brown oil with a 
green fluorescence ; this is another anhydride, with the composition C,,H,,O3. 

All forms of the acid are sparingly soluble in water and ether, and easily 
soluble in alcohol. The solutions possess the bitter-sweet taste of bile. The 
alkaline salts are crystalline and soluble in water, but precipitated by strong 
solutions of alkalies or their carbonates. The barium salt is much more 
soluble in cold water (1-30) than the corresponding salts of the allied acids 
described below. Cholalic acid and its soluble salts turn the plane of polarisa- 
tion to the right.4 Methyl and ethyl ethers of cholalic acid have been 
obtained. 


The formula of cholalic acid was first established by Strecker® as 
C,,H,,0., and this formula, after some dissent,® is now generally 
accepted. With regard to its constitution, in spite of a vast amount of 
labour on the subject, we are still only possessed of very fragmentary 
and uncertain information. It is certainly a monobasic acid, and must 


1 Mylius, Zéschi. f. physiol. Chem., Strassburg, 1888, Bd. xii. 8. 262. 

2 See Maly, Hermann’s ‘‘ Handbuch,” Bd. v. (2), S. 136. 

3 Schotten, Ztschr. f. physiol. Chem., Strassburg, 1886-7, Bd. x. 8S. 175; xi. S. 268. 

4 Hoppe-Seyler, Journ. 7. prakt. Chem., Leipzig, 1863, Bd. lxxxix. S. 265; E. Vahlan, 
Ztschr. f. physiol. Chem., Strassburg, 1896, Bd. xxi. 8. 253. 

> Loc. cit. 

6 Latschinoff, Ber. d. deutsch. chem. Gesellsch., Berlin, 1887, Bd. xx. 8. 1968. 


CLEAVAGE PRODUCTS OF THE BILE ACIDS. 381 


therefore contain one carboxyl group (COOH), and according to Mylius?! 
it also contains one secondary (CHOH) and two prim ary alcohol 
groups (CH,OH). 

The evidence for this is derived from its behaviour on cautious 
oxidation. It first yields, when oxidised, monobasic dehydrocholalie acid 
(Cy4H.,,05)," and on further oxidation tribasie bilic, or bilianic age 
C,,H,,0,).3 These changes may be expressed by supposing that, 
the formation of dehydrocholalic acid, the two primary alcohol Pai 
form aldehyde groups (H—-C =O), and the secondary group, a ketone 
group (C= 0), and that in the further formation of bilianic acid the two 
aldehyde groups ee into (acid or) carboxyl groups, so producing a 
tribasic acid; while besides, in the rest of the molecule, an additional 
ketone group is formed, as shown by the following formule :— 

Cholale acid, C,,H.,(CHOH)(CH, OH), (COOH), on oxidation forms, 
in place of one secondary alcohol group (CHOH) and two primary 
alcohol groups (CH,OH), one ketone group (CO) and two aldehyde 
groups (COH), thus yielding dehydrocholalic acid, C,,H,,(CO)(COH), 
(COOH), in which, on further oxidation, an additional ketone group is 
formed, and the aldehyde groups change into carboxyl groups (COOH), 
thus yielding the tribasic acid, bilianic (or bile) acid, C,,H.,(CO.),(COOH),. 

Scarcely anything is known of the arrangement of the atoms in the 
hydrocarbon part of the molecule. Mylius 4 has obtained a reaction 
between cholalic acid and iodine, in solution, with the formation of a 
blue compound, which is ecrystallisable and becomes easily dissociated in 
the same manner as iodide of starch. For example, in solution, it 
becomes decolorised on heating. 

This substance is probably an addition product of cholalic acid and 
iodine, and so points out that the hydrocarbon radicle of the acid is not 
fully saturated ; beyond this, however, we know nothing of its composition. 

Desoxycholalie acid is a reduction compound obtained by Mylius® of 
the formula C,,H,,0,. 


Choleic acid ® was first found in the preparation of cholalic acid from ox 
bile, and separated from it by means of the more sparing solubility of its barium 
salt. According to Lassar-Cohn, it also occurs in human bile, and its formula 
So OB s BAO Tatechinee 7 its diseavered ascribed to it the eral Gi) 8 WO ip 
From Lassar-Cohn’s® formula it appears to be isomeric, or perhaps identical, 
with ae acid. 

Fellic acid® (C,,H,,O0,) is an acid which has been obtained from human 
bile ; it is crystalline, insoluble in water, and forms insoluble barium and 
magnesium salts. 

The acids formed by the cleavage of the peculiar bile acids found in the bile 
of the pig and goose have been already mentioned in treating of these acids. 


1 Ber. d. deutsch. chem. Gresellsch., Berlin, 1886, Bd. xix. S. 369, 2000. 

? Hammarsten, zbid., 1881, Bd. xiv. S. 71 (Dehydrocholsaiire) ; Lassar- Cohn, zbid., 1892, 
Bd. xxv. 8. 805 ; Ztschr. f. physiol. Chem., Strassburg, 1892, Bd. xvi. S. 488. 

3 Cleve, Bull. Soc. chin., Paris, tome XXEV. 

+ Zischr. f. physiol. Chem.., Strassburg, 1887, Bd. xi. S. 306 ; Ber. d. deutsch. chem. 
Geselisch., Berlin, 1887, Bd. XX. S. 683. 

5 Loc. cit. 

8 Choleinsdéure of Latschinoff, Ber. d. deutsch. chem. Geselisch., Berlin, 1885, Bd. xviii. 
S. 3039. 

7 Loc. cit. 

8 Ber. d. deutsch. chem. Gesellsch., Berlin, 1894, Bd. xxvii. S. 1339. 

® Fellinsture of Schotten, Zischr. if physiol. Chem.. Strassburg, 1887, Bd. xi. S. 268. See 
also Lassar-Cohn, zbid., 1894, Bd. xix. 8S. 563. 


382 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


The acids formed as cleavage products from human bile are cholalie, 
choleic, and fellic acids. 

Cholalic acid and its allies, on boiling with acids, on heating in the 
dry state, or by putrefaction, lose water, and become converted into 
anhydrides, or, as they are called, dyslysins. The dyslysin corresponding 
to cholalic acid has the formula C,,H.,,0,; it is found in feces; is a white 
amorphous substance, insoluble in water and alcohol, soluble in ether 
and melting at 140° C. Another compound, choloidinic acid, is formed, 
as an intermediate stage, of the formula C,,H,,O, On boiling with 
alkalies, dyslysin takes up water, and is reconverted into cholalic acid. 

The bile pigments and their derivatives.—The variations in the 
colour of bile early attracted attention, and Gmelin} in 1826, first 
obtained proof of a relationship between these colours, and described 
the test which still bears his name. He was aware that the play of 
colours was due to a process of oxidation, and made an experiment to 
illustrate this by acidifying bile with hydrochloric acid, and enclosing 
it ina tube from which the air was shut off by a mercury trap. Under 
these circumstances no change in colour took place; but on exposing 
the acidified bile to the air,a green colour slowly developed. He also 
accurately described the play of colours obtained on oxidising with 
nitric acid. 

Berzelius? precipitated biliverdin from ox bile with barium chloride, 
purified it to some extent, and described its properties, but he fell into 
the error of supposing that it was identical with chlorophyll? 

Heintz, preventing oxidation by exclusion of air, extracted from 
gallstones a brown amorphous pigment, which he named _biliphain. 
He analysed it, and converted it by dissolving in sodium carbonate, and 
leading oxygen through the solution into a green pigment, biliverdin. 
His biliphiin corresponded to the bilirubin of the present day, and his 
experiment shows well the connection between the two pigments. 

Valentiner,? in 1859, was the first to obtain bilirubin in a crystalline 
form, by dissolving in chloroform, from which, on evaporation of the 
solvent, it crystallises in microscopic crystals. From this discovery 
onwards, research on the bile pigments took a more exact form, as 
methods for the isolation of the pigments were discovered and. perfected.® 

Although a considerable number of more or less well-characterised 
bile pigments have been described, only two are found under normal 
conditions in the bile, these are bilirubin and biliverdin; the others are 
obtained by artificial means from these, are found under pathological 
conditions only in the body, or are formed after death. The colour of 
the bile is a compound of the colour of these two pigments, and varies 
with the varying ratio of their amounts through all shades between 

1 Tiedemann and Gmelin, ‘‘ Verdauung nach Versuchen,” 1826. 

2 “Chemie,” S. 281. 

3 The spectra of phylloporphyrin and hematoporphyrin and their derivatives are almost 
identical, and in other respects the substances closely resemble each other, so that there is 
undoubtedly a relationship between them (Schunck and Marchlawski, Proce. Roy. Soc. 
London, Jan. 1896). Now, phylloporphyrin is a derivative of chlorophyll, and hzemato- 
porphyrin is isomeric with bilirubin, so that there may be some remote connection between 
biliverdin and chlorophyll. 

4 Jahresb. ti. d. Fortschr. d. ges. Med., Erlangen, 1851, Bd. ii. 8S. 59; Ann. d. Phys. 
u. Chem., Leipzig, 1851, Bd. lxxxiv. S. 106. 

5 Jahresb. ii. d. Fortschr. d. ges. Med., Erlangen, 1859, Bd. ii. S. 87. 

6 Briicke, Untersuch. z. Naturl. d. Mensch. u. d. Thiere, Bd. vi. S. 173; Stadeler, 


Vrtljschr. d. naturf. Gesellsch. in Zurich, 1863, Bd. viii. S. 1; Ann. d. Chem., Leipzig 
1864, Bd. exxxii. S, 323. 


oe 


BILE PIGMENTS AND THEIR DERIVATIVES. 383 


reddish-brown and grass-green. To the variation in relative amount of 
these two pigments is also due the difference in colour between fresh 
and stale bile. When bile stands in the gall bladder, its pigments 
become reduced, the biliverdin is converted into bilirubin, and the 
colour becomes yellow or brown. Fresh human bile has also a green 
colour, but that observed in the post-mortem or dissecting-room is 
always brown, because of this process of reduction. These two normally 
occurring bile pigments are related to each other in a manner analogous 
to hemoglobin and oxyhzmoglobin; bilirubin (C,,H,,N,O,) on oxidation 
passes into biliverdin (C,,H,,N,O,). 

Haycraft and Scofield} observed in the gall bladder itself reduction 
going on, as shown by the fact that, while the bile in the middle of the 
gall bladder was green, the thicker bile mixed with mucus near the 
bladder wall was orange-brown, and the mucous membrane itself of a 
brown colour. To this slow reduction Haycraft and Scofield ascribe 
also the presence of bilirubin and not biliverdin in the gallstones of 
oxen, although the latter is the chief pigment found in ox bile. Putre- 
faction readily brings about the same reduction in the bile pigments. 
Bile with the bilirubin tint predominant does not turn green from 
oxidation of this pigment to biliverdin, when it is exposed to the air, 
unless it be made strongly alkaline with caustic alkali. In this increased 
readiness to take up oxygen in alkaline solution, bilirubin resembles a 
large number of other organic substances, such as pyrogallol and pyro- 
catechin. Haycraft and Scofield were also able to induce these changes 
by the action of nascent oxygen and of ozone. Working with a battery of 
four or five Grove cells, and leading from platinum electrodes into brown- 
coloured bile (in a beaker or on filter paper), they found that the oxygen 
developed at the anode caused in a few minutes a change in colour of 
the bile, through green and blue into violet, followed by bleaching. On 
reversing the poles, so that reduction instead of oxidation took place at 
this spot, an inverse change in colour back to brown was observed. 

Bilirubin and biliverdin have chemically the character of weak acids, 
as is shown by the ease with which they unite with bases to form salt- 
like bodies. Such compounds with alkalies are soluble in water, but 
with alkaline earths are insoluble; as, for example, the compound of 
bilirubin with calcium, which makes up the bulk of red gall stones, and 
forms a convenient source for the preparation of the pigment. Neither 
pigment has a spectrum showing absorption bands, but in each there is 
continuous absorption at the blue end of the spectrum. 

Bilirubin has borne in the history of the bile pigments many names, 
such as cholepyrrhin, biliphain, cholephain, and bilitulvin; but, fortunately, 
all these names have now disappeared, and the properties of the sub- 
stances described under them by different observers, so far as they have 
been substantiated, have been aggregated under one name and to one 
substance, bilirubin, the red colouring matter of bile. Bilirubin is a con- 
stant constituent of bile, and is found besides as a calcium compound in 
red gall stones. It is also present in traces in the serum of some animals. 
Hammarsten? found it in the serum of the horse. By precipitating 
the serum globulin with acetic acid, the pigment is thrown down with 
the globulin, and on drying the precipitate and extracting with chloro- 
form, bilirubin is dissolved out. It seems, however, to be absent in 


1 Ztschr. f. physiol. Chem., Strassburg, 1889, Bd. xiv. S. 173. 
2 Jahresb. ti. d. Fortschr. d. Thier-Chem., Wiesbaden, 1878, Bd. viii. S. 129, 


384 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


human serum and that of the ox. Most important, from the point of 
view of the origin of the bile pigments, is the discovery that the 
microscopic crystals often found in old blood clots and extravasations, 
and described by Virchow! as hematoidin, are usually bilirubin; this 
shows that the bile pigments are probably products of disintegration of 
hemoglobin. Here it is needful to guard against mistaking lutein for 
bilirubin. The two substances may be distinguished by their solubilities. 
Both are soluble in chloroform, but bilirubin is thrown out of solution 
on the addition of an alkali (from the formation of a compound with the 
alkali insoluble in chloroform), while lutein is not so precipitated. 
Bilirubin is also found, in cases of jaundice, in the urme and in the 
tissues. 


Bilirubin is best prepared from the gallstones of the ox, which are very 
common and easily procurable. The gallstones are washed, ‘dried, powdered, 
and then extracted in turn with ether, boiling alcohol, and boiling water, to 
remove cholesterin (which is, however, rarely present in appreciable quantity 
in ox gallstones) and bile acids. The residue is treated with dilute hydro- 
chlorie acid, to set free the bilirubin from its calctum combination, washed 
with water and alcohol, and finally extracted with boiling chloroform, in which 
the bilirubin dissolves. 

The chloroform is distilled from the extract, and the impure bilirubin is 
freed from an accompanying substance, bilifuscin, by digesting with absolute 
alcohol, in which this substance dissolves, and is then redissolved in chloro- 
form. It is purified further by throwing out of concentrated solution in 
chloroform, by the addition of absolute alcohol, redissolving and reprecipitating 
repeatedly. It is lastly dissolved in as little as possible of boiling chloroform, 
from which it crystallises on cooling. 

In amorphous condition, as when precipitated by alcohol and dried, 
bilirubin is an orange-coloured powder; when crystalline, it is of a dark red 
or reddish-brown colour, resembling chromic acid. The crystals are rhombic 
plates with rounded-off angles; they are more easily soluble in chloroform 
than in any other solvent; somewhat soluble in carbon bisulphide and amyl 
alcohol ; nearly insoluble in ether, alcohol, turpentine, benzol, and glacial acetic 
acid. Bilirubin is soluble easily in alkalies and their carbonates, combining 
with them to form salts. Calcium chloride, added to these solutions, pre- 
cipitates the caleium compound (C,,H,,N,O.).Ca as a rust-coloured precipitate. . 
Treated with sodium amalgam, bilirubin yields hydrobilirubin ; on oxidation 
it passes into biliverdin and more highly oxygenated compounds. Several 
formule have been proposed for bilirubin ;? the most generally accepted is 
that of Maly (C,,H,,N,O,). Bilirubin is oxidised in alkaline solution in the 
air to biliverdin in the same manner as bile, which owes this reaction to the 
bilirubin it contains. 

Ehrlich’s test.2—Ehrlich describes a colour test for bilirubin, which is not 
given by biliverdin. To a solution of bilirubin in chloroform an equal volume 
of a watery solution of diazobenzolsulphonic acid is added, and just enough 
alcohol to cause the two fluids to mix, when the fluid turns a beautiful red 
colour ; on adding, drop by drop, concentrated hydrochloric acid, the colour of 


1 Virehow’s Archiv, 1847, Bd. i. S. 379, 407. See also Robin, Compt. rend. Acad. d. se., 
Paris, 1855, tome xli. p. 506; Jaffé, Virchow’s Archiv, 1862, Bd. xxiii. S. 192 ; E. Salkowski, 
Hoppe-Seyler’s Med.-chem. Untersuch., Berlin, 1868, S. 436. 

2 Stiideler, Ann. d. Chem., Leipzig, 1864, Bd. exxxii. S. 323; Thudichum, Journ. f. 
prakt. Chem., Leipzig, 1868, Bd. civ. S. 401; Maly, ibid., Bd. civ. S. 28; Maly, Ann. d. 
Chem., Leipzig, 1876, Bd. elxxxi. S. 106; Nenckiu. Sieber, Ber. d. deutsch. chem. Geselisch., 
Berlin, 1884, Bd. xvii. S. 2275. 

3 Centralbl. f. klin. Med., Bonn, 1883, Bd. iv. S. 722; Krukenberg, ‘‘Chem. Unter- 
such.,” 1886, S. 77. 


BILE PIGMENTS AND THEIR DERIVATIVES. 385 


the solution changes through violet into blue; if a layer of potassium hydrate 
solution is now introduced beneath the blue solution, there develops an 
(alkaline) bluish-green zone underneath, separated from the blue solution above 
by a red band where the reaction is neutral. 

Biliverdin is present in all green-coloured biles, and may be obtained from 
them, by adding a solution of barium chloride, as a dark green precipitate, 
which may be washed with water and alcohol, and decomposed by dilute hydro- 
chloric acid, when the biliverdin remains as a flocky precipitate ; this is freed 
from fats by washing with ether, and is then dissolved in alcohol ; on evaporat- 
ing the alcohol, the biliverdin is left behind as a dark green scale. Biliverdin 
can best be prepared pure from an alkaline solution of bilirubin. This is 
allowed to oxidise by exposing to the air in a shallow dish, until it turns a 
brownish-green colour; the solution is then precipitated with hydrochloric 
acid, which sets free insoluble biliverdin from the soluble compound with the 
alkali; the precipitate is washed with water till free from hydrochloric acid, 
dissolved in alcohol, and reprecipitated by the addition of water. This 
precipitate is washed with chloroform to remove traces of bilirubin, and pure 
biliverdin remains behind, being insoluble in chloroform. It forms a very 
dark green amorphous powder, insoluble in water, ether, chloroform, carbon 
bisulphide, or benzol; but soluble with a fine green colour in alcohol, glacial 
acetic acid, or concentrated sulphuric acid. According to MacMunn,! there is 
a green pigment in ox bile which differs from that prepared as above, in being 
soluble in chloroform. Biliverdin does not easily crystallise ; it is said to be 
occasionally obtainable, by evaporating a solution in glacial acetic acid, in 
rhombic plates with rounded angles. With alkalies, biliverdin forms soluble 
compounds, giving brownish-green solutions, from which biliverdin falls as a 
flocky precipitate on the addition of acids. Calcium, barium, and lead salts 
form insoluble compounds with biliverdin; these are thrown down as dark 
green precipitates on addition of solutions of the corresponding salts to an 
alkaline solution of biliverdin. By nascent hydrogen, biliverdin is converted 
through bilirubin into hydrobilirubin. Different formule are given by different 
authors for biliverdin. Stideler? calculated it as C,,H,,N,O;, from analyses 
by Heintz. Heintz himself* gives C,,H,,.N,O,. This formula assumes that 
in passing from bilirubin to biliverdin, the molecule takes up water as well as 
oxygen (C,,H,,.N,O,+H,O+O0=C,,H,,N,O-;), but the accuracy of this is 
denied by Maly, both from analysis and the amount of increase in weight 
observed in passing from bilirubin into biliverdin. He gives the formula of 
biliverdin as C,,H,,.N.O,, and this result is confirmed by Thudichum,° except 
that the latter halves the formula, giving C,H,NO,. 


Gmelin’s test for bile pigments.—This very distinctive test for the bile 
pigments has already been mentioned. It depends upon the remarkable 
changes in colour accompanying the oxidation of bilirubin. In such 
oxidation the other normal bile pigment, biliverdin, is first produced ; 
and this in turn, by further oxidation, is converted into a blue pigment, 
bilicyanin; after this follows, according to some, a purple pigment 
(bilipurpurin) before the final stage of oxidation to a yellow compound, 
choletelin. The production in series of these artificial products of 
oxidation is what constitutes Gmelin’s test. 

If either a solution of bilirubin or some diluted bile be carefully 


1 Journ. Physiol., Cambridge and London, 1885, vol. vi. p. 25. 

2 Ann. d. Chem., Leipzig, 1864, Bd. cxxxii. 8. 323. 

3 Jahresb. ii. d. Fortschr. d. ges. Med., Evlangen, 1851, Bd. ii. S: 59; Ann. d. Phys. 
u. Chem., Leipzig, 1851, Bd. lxxxiv. S. 106. 

4 Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1874, Bd. iv. S. 302; and Her- 
mann’s ‘‘ Handbuch,” Bd. vy. (2), S. 159. 

5 Journ. f. prakt. Chem., Leipzig, 1868, Bd. civ. S. 220. 


VOL, I.—25 


386 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


poured on the surface of fuming nitric acid in a test tube, so as not 
to mix the two liquids, a series of coloured zones appears in the 
lower part of the column of bile above the acid; next to the acid is the 
most oxidized product (choletelin), represented by a yellow-red zone; 
above this is a purer red, passing into a purple, which is replaced by a 
blue zone (bilicyanin); and, lastly, there is a very broad green zone, 
corresponding to the least oxidized product (biliverdin). The test may 
also be made by spreading out the bile in a thin film over the inside 
of a porcelain capsule and placing a drop of fuming nitric acid in the 
centre of this film, when a series of colours develop in the above order 
around the drop; or perhaps, most conveniently of all, according to 
Rosenbach’s modification, by moistening a piece of filter paper in the 
suspected fluid, and placing a drop of fuming nitric acid in the 
centre. 

Huppert’s test.—Huppert’s test consists in precipitating calcium 
bilirubinate, by the addition of milk of lime, or calcium chloride and 
ammonia, to a solution of an alkaline bilirubinate (or alkaline bile); 
after washing with water, the precipitate is boiled for some minutes 
with alcohol acidified with sulphuric acid, when, in presence of bile 
pigments, the solution develops an emerald-green or blue-green colour. 


Bilicyanin is the name given to the substance present at that stage of 
oxidation of bilirubin by artificial means, such as fuming nitrie acid, when 
the solution has a blue colour. The stage is a very transient one, and, though 
many have worked at the subject, no one has yet succeeded in isolating the 
substance to which the blue colour is due. It is probably an unstable 
oxidation product, intermediate between biliverdin and choletelin. A blue 
solution, which keeps for some hours, may be obtained by adding to a solution 
of bilirubin in chloroform a little nitric acid, and shaking till a violet tint 
first appears. Rectified spirit is then quickly added ; this very much slows the 
completion of the oxidation, so that the blue colour is preserved for some 
time. If an ammoniacal solution of bilirubin be mixed with strong fuming 
nitric acid, a little at a time, and excess of acid removed each time by addition 
of ammonia, a dark flocky precipitate is obtained, from which biliverdin can 
be removed by alcohol, leaving behind a deep dark blue powder.1 Heynsius 
and Campbell? have found that certain gall stones in man, after extraction 
with alcohol and ether, yield to dilute acids a violet-brown pigment, which 
they identified as bilicyanin spectroscopically. 


Jaffé* first observed that the blue stage of the oxidation process 
gave an absorption spectrum; in strong solution, it shows a wide band 
beginning to the red side of D, and ending between D and E; on dilution 
this band resolves itself into two dimmer bands (« and 8). As oxida- 
tion proceeds, a third band (y) appears between 6 and F, whilst the two 
first mentioned gradually become fainter and disappear. This third 
band does not belong to the blue stage (bilicyanin), but to the substance 
formed in the final stage of the oxidation (choletelin). The violet 
colour obtained before the final permanent reddish brown is probably 
due to an admixture of the latter colour with blue. é 


Bilifuscin is a substance separated in the preparation of bilirubin from 
gall stones; very little is known of its properties or chemical relationships. 


1 Jaffé, Centralbl. f. d. med. Wéissensch., Berlin, 1868, Bd. vi., S. 241; Journ. f. 


prakt. Chem., Leipzig, 1868, Bd. civ. S. 401. 
2 Arch. f. d. ges. Physiol., Bonn, 1871, Bd. iv. S. 537. 3 Loc. cit. 


BILE PIGMENTS AND THEIR DERIVATIVES. 387 


In the presence of bilirubin it is soluble in chloroform, although diffi- 
eultly soluble in this solvent alone ; hence, after treatment with chloroform in 
preparing bilirubin, both substances come into solution. When the chloroform 
solution is concentrated, and excess of alcohol added, the bilirubin is pre- 
cipitated, while the bilifuscin remains soluble, and is found in the alcoholic 
filtrate along with some cholesterin and higher fatty acids. After removal of 
the alcohol by evaporation, the residue is treated with ether, which dissolves 
out these impurities, and chloroform, which removes any traces of bilirubin 
left behind. The almost black, dark brown residue so obtained, was termed 
bilifuscin by Stideler ;! who made incomplete analyses of it, from which he 
deduced the formula C,,H,,N,O, (?). When quite pure, bilifuscin does not 
give Gmelin’s reaction ;* it is found in very old post-mortem bile? as well as 
in gallstones, but not in fresh bile. Bilifuscin has only been obtained in an 
amorphous form; it is soluble in alcohol and in alkalies; almost insoluble in 
water, ether, and chloroform ; its relationship to bilirubin is unknown. The 
biliprasin of Stadeler+ is probably only a mixture of bilifuscin and biliverdin. 
Bilihumin is a name used by the same observer to designate a black mass 
taken up by strong solution of ammonia, from the residue of gallstones 
which have been thoroughly exhausted with chloroform, alcohol, and ether ; 
it does not give Gmelin’s reaction. 


Hydrobilirubin (C..H,,N,O0,), a reduction product of bilirubin, is an 
important substance, from the connection it makes between the bile 
pigments, those of the urine and the products of disintegration of 
heemoglobin. 


Maly ® first obtained it by the action of nascent hydrogen (from sodium 
amalgam) on an alkaline solution of bilirubin; biliverdin similarly treated 
also yields it, being first converted into bilirubin. At the end of the reaction 
the light brown coloured fluid is decanted from the mercury, and acidified 
with hydrochloric acid. On the addition of the acid the solution becomes 
much darker in colour, and abundant dark brown flocks of hydrobilirubin 
separate out; these are separated from the solution, dissolved in ammonia, 
reprecipitated with hydrochloric acid, and washed with water. After so 
washing away all the salts the pigment becomes less soluble in water. After 
drying it forms a dark reddish-brown powder, easily soluble in alcohol, or a 
mixture of alcohol and ether; not so soluble in ether alone. These solutions 
have, when concentrated a reddish brown, when dilute a rose colour. 
Chloroform dissolves it to form a yellowish-red solution. In alkalies it 
dissolves to a pale yellow solution, becoming red on the addition of an acid. 
Maly ascribes the yellow colour to a compound with the alkali, the red to 
the free substance. 


Hydrobilirubin in solution has an absorption spectrum, showing a 
dark band between } and F. On addition of ammonia this band fades 
out, but reappears a little to the left on the addition of a trace of zinc 
chloride to the solution. This solution containing zinc chloride and 
ammonia has a rose colour and a green fluorescence. Hydrobilirubin 
once formed does not readily give Gmelin’s test; that is to say, it is not 
easily oxidisable again to bilirubin or biliverdin. 

Maly recognised his new substance as identical with a urinary 


1 Vrtljschr. d. naturf. Gesellsch. in Zurich, 1863, Bd. viii. 

2 Briicke, Untersuch. z. Naturl. d. Mensch. u. d. Thiere, 1860, Bd. vi. S. 173. 

3 Simony, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1876, Bd. vi. S. 75. 
4 Loc. cit. 

5 Jalresb. ii. d. Fortschr. d Thier-Chem., Wiesbaden, 1872, Bd. ii. S. 232. 


388 CHEMISTRY OF THE DIGESTIVE PROCESSES, 


pigment, already deseribed under the name of urobilin, and discovered 
by Jaffe? under pathological conditions in the urine. Immediately 
before Maly’s discovery, Hoppe-Seyler* had described a brownish-red 
substance, which he obtained by the action of zinc and hydrochloric 
acid (ze. nascent hydrogen), on hematin; this, he afterwards stated to 
be impure hydrobilirubin.? When one considers that bilirubin is poured 
into the intestine with the bile, and that it is here subjected to reducing 
influences, as is shown by the frequent presence of hydrogen in the 
intestinal gases, it is natural to suppose that a considerable conversion 
of bilirubin into hydrobilirubin goes on in the intestine. The pigments 
of the feces, which must arise mainly from the bile pigments, do not 
give Gmelin’s reaction; extraction of the feces with dilute spirit, 
evaporating and extracting the residue with strong spirit, yields a 
solution which shows the spectrum of hydrobilirubin.* This pigment 
of the feces had been already described as stercobilin by Vanlair and 
Masius.® Jaffé® considered it as identical with his urobilin. Maly 
gives the above theory of its formation in the intestine from bilirubin, 
and looks upon all three, as well as Hoppe-Seyler’s compound from 
hematin, as one substance, namely, hydrobilirubin.? 

It is generally accepted that these substances are closely related, if 
not identical, and their relationship is of the utmost importance in con- 
necting the pigments of the bile with the waste products of hzemoglobin.§ 

Choletelin.—Besides this important reduction derivative of bilirubin, 
we also owe to Maly® the discovery of choletelin, the final substance 
obtained in its oxidation by nitric acid. 

At the end of the reaction a yellow colour is obtained, not widely 
different from that of the bilirubin from which the reaction started ; 
when this condition is reached, all the intermediate products have been 
converted by oxidation into one substance. 


Choletelin is best prepared, according to Maly,!° by leading a stream of 
nitrous fumes (prepared by acting on arsenious acid with nitric acid) through 
bilirubin suspended in alcohol. The fluid passes through the colours of 
Gmelin’s reaction, and finally a clear, pale, yellowish-red solution is left; this 
is thrown into water, when choletelin separates out in rust-coloured flocks, 
which form, when dried, a brown powder. Choletelin is amorphous and 
probably represented by the formula C,,H,,N,O,; it is soluble in alcohol, 
ether, chloroform, and acetic acid. It is also soluble in alkalies, and 
precipitated from such solution by acids. In acid solution it shows a dim 
absorption band lying between } and F, and corresponding to the band y 
observed by Jaffé in solutions of bilicyanin. In neutral alcoholic solution this 
band disappears. 


1 Virchow’s Archiv, 1869, Bd. xlvii. S. 405-418. 

* Jahresb. ti. d. Fortschr. d. Thier-Chem., Wiesbaden, 1871, Bd. i. S. 80 ; Med.-chem. 
Untersuch., Berlin, 1871, S. 536. 

3 Ber. d. deutsch. chem. Gesellsch., Berlin, 1874, Bd. vii. S. 1065. 

* Maly, Hermann’s ‘‘ Handbuch,” Bd. v. (2), S. 162. 

5 Juhresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1871, Bd. i. S. 229. 

6 Arch. f. d. ges. Physiol., Bonn, 1871, Bd. iv. S. 537. 

* Hermann’s ‘‘ Handbuch,” Bd. v. (2), S. 162. 

® See MacMunn, Journ. Physiol., Cambridge and London, 1889, vol. x. p. 71; Eichholz, 
Journ. Physiol., Cambridge and London, 1893, vol. xiv. p. 326; Garrod and Hopkins, 
Journ. Physiol., Cambridge and London, 1896, vol. xx. p. 113; Garvoch, ibid., 1897, vol. 
xxi. p. 190. 

9 Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1868, Bd. lvii. Abth. 2, S. 107; 1869, 
Bd. lix. Abth. 2, S. 602. 

10 Hermann’s ‘‘ Handbuch ” Bd. vy. (2), S. 165. 


BILE PIGMENTS AND THEIR DERIVATIVES. 389 


The halogens react energetically with bilirubin, forming substitution 
products. When bromine acts on bilirubin, a series of changes in colour 
take place, exactly counterfeiting those observed in Gmelin’s reaction. 
The reactions are, however, quite different ; and the process is not, as one 
might naturally have expected, an oxidation, but a substitution of 
bromine for hydrogen ! (2C,,H,,N,O,+3 Br, = C,,H,,Br,N,O,+3H Br).? 


The reaction is best shown by adding a dilute solution of bromine in 
chloroform, cautiously, to a solution of bilirubin, also in chloroform. The solu- 
tion changes through green, blue, and red into yellow, as the bromine is added, 
and may be stopped and examined at any stage. If chloroform free from 
aleohol be used, a tribromo derivative separates out of solution. Decanted 
from chloroform, dissolved in alcohol, and reprecipitated by adding water, this 
compound is obtained as a dark blue powder, soluble in alcohol, in ether, or 
in chloroform containing alcohol; but insoluble in pure chloroform, or in 
water. Alkalies split it up, yielding biliverdin. 


Nothing is known of the chemical constitution of the bile pigments, 
and very little of the intermediate stages in their production from 
hemoglobin. Their connection with hemoglobin rests on—(1) The 
identity of heematoidin produced in old blood clots with bilirubin. (2) 
The identity of Hoppe-Seyler’s reduction product obtained from hematin, 
and thus indirectly from hemoglobin, with Maly’s hydrobilirubin. 
(3) The absence of bile pigments in such animals as have no hemoglobin.* 
(4) The fact that anything causing increased destruction of red blood 
corpuscles, or the intravenous injection of hemoglobin, causes an increased 
secretion of bile pigments.4 (5) Hzmatoporphyrin is isomeric with 
bilirubin, shows with nitric acid colour changes somewhat resembling 
Gmelin’s reaction, and yields on reduction with nascent hydrogen a 
substance closely resembling and probably isomeric with hydrobilirubin. 
According to Nencki and Sieber,’ bilirubin is formed in the liver by the 
hemoglobin first splitting up into hematin and proteid. The hematin 
thus formed then takes up water, loses its iron, which is retained in 
combination in the liver, and so forms bilirubin, thus— 

C,,H,.N,0,Fe + 2H,O—Fe=C,,H,,N,0,; or 2(C,,H,,N,05) 


(hematin) (bilirubin) 


Direct experiments on the formation of bile pigments from hemo- 
globin apart from the liver have been carried out by Latschenberger.® 
If the corpuscles and serum of horse blood be separately injected sub- 
cutaneously at different parts in the horse, and after the lapse of about 
twelve days the animal be killed, and the parts where the injections have 
been made are examined, it is found that while, at the part where the 


1Thudichum, Journ. Chem. Soc., London, 1875, vol. xxviii. p. 389 ; Maly, Sitzungsb. d. 
k. Akad. d. Wissensch., Wien, Ba. Ixxii, Abth. 2. 

2 Maly, Hermann’s “« Handbuch,” Bd. v. (2), S. 167. 

3 Hoppe-Seyler, Arch. f. d. ges. Physiol., Bonn, 1877, Bd. xiv. S. 399. See, however, 
ieenlbere, Centralbl. J. d. med. Wissensch., Berlin, 1883, No. 44, 8. 785. 

4¥Frerichs, Arch. f. Anat. u. Physiol., Leipzig, 1856, S. 59: W. Kiihne, Virchow’s Archi, 
1858, Bd. xiv. S. 310; Nothnagel, Berl. klin. Wehnschr., 1866, vol. vi. S. 31; Tarchanoff, 
Arch. f. d. ges. Physiol., Bonn, 1874, Bd. ix. S. 329; Minkowski and Bassorin, Arch. f. 
exper. Path. u. Pharmakol., Leipzig, 1887, Bd. xxiii. 8. 145. 

> Ber. d. deutsch. chem. ‘Gesellsch.. Berlin, 1884, Bd. xvii. S. 2275 ; Monatsh. f. Chem., 
Wien, 1888, Bd. ix. S. 115; Arch. fh exper. "Path. u. Pharmakol., Leipzig, 1888, Bd. xxiv. 
Ss. 430. 

6 Monatsh. f. Chem., Wien, 1888, Bd. ix. S. 52; Sitzwngsb. d. k. Akad. d. Wissensch., 
Wien, 1888, Bd. xcvii. Abth. 2b, S. 15. 


390 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


serum has been injected the tissues present a normal appearance and 
contain no bile pigments, on the other hand, round the spot where the 
corpuscles have been injected, the tissues contain, besides fluid blood, a 
substance in flakes, varying in colour from dark orange to bright yellow, 
composed of small spherical masses about a quarter “of the size of red 
corpuscles, which give Gmelin’s reaction very readily. The same result 
may be obtained on injecting crystallised ‘hemoglobin, suspended in 
water; here granular masses of « greenish-yellow “colour are obtained, 
which also give Ginelin’s reaction. 


Spectra of bile.—A considerable amount of continuous absorption at 
both ends of the spectrum is found on examining the bile of any animal, 
but in some animals the bile also shows well-marked absorption bands.! 

Cholohematin.—The most characteristic of these band-spectra is that 
exhibited by ox or sheep bile which has stood for some time in contact with 
air. This spectrum, according to MacMunn,? “ presents in a deep layer three 
bands, in a thinner one four bands, and in a still thinner a fifth band at F is 
visible.” The spectrum is well seen in an alcoholic solution of evaporated ox 
bile. Of the four well-marked bands, two lie close to the D line, on either side 
of it; a third lies in the red, immediately to the right of the C line; and the 
fourth covers the E and b lines. No pure material has yet been isolated, 
so that it is not even known whether the spectrum is due to one or several 
substances. MacMunn® has obtained an amorphous residue of a dark sap- 
green colour, containing abundantly material which gives the spectrum, by 
treating ox bile with absolute alcohol and acetic acid, alternately dissolving in 
chloroform and ether, and washing the chloroform solution with water. This 
material has been named cholohematin by MacMunn, from its occurrence in 
bile and its supposed origin from hematin. 


7 


The spectrum is not exhibited by jresh ox or sheep bile,* but is first | 


developed on standing in contact with air, probably from a chromogen present 
in the fresh bile. The bands near D first appear, to be followed much later by 
the other two; the appearance of the spectrum is not a result of putrefaction.® 

MacMunn‘* obtained a spectrum closely resembling that of hematoporphyrin 
by the action of sodium amalgam on cholohematin, prepared as above indicated, 
from which he argues that the latter is a derivative of hematin. 

The fresh bile of the mouse shows a well-marked band at F, corresponding 
to the urobilin band ; and more or less distinct bands in the same position in 
the bile of other animals indicate, according to MacMunn, traces of urobilin 
in these fluids. Characteristic absorption-band spectra are also found in the 
bile of the guinea-pig, pig, rabbit, and crow. Human bile shows no bands, but 
an alcoholic extract exhibits a well-marked band at D; these, as well as the 
spectra of Gmelin’s and Pettenkofer’s reactions, are shown in Plate III. at 
the end of this volume. 


Other constituents of bile-—Besides the bile salts and bile pig- 
ments, which are normally found only in the bile, other constituents are 
present which are also found in other parts of the body; these are 
cholesterin, fats, soaps, and lecithin, besides minute traces of urea and 
of the diastatic ferment already mentioned. 


1 Bogomoloff, Centralbl. f. d. med. Wissensch., Berlin, 1869, vol. vii. S. 580. 

2 «The Spectroscope in Medicine,” London, 1880, Dp. 158. 

3 Journ. Physiol., Cambridge and London, 1885, vol. vi. p. 24. 

4 Bogomoloff, Zoc. cit. ; Heynsius and Campbell, Arch. f. d. ges. Physiol., Bonn, 1871, 
Bd. iv. 8. 540. 

5 Gamgee, ‘‘ Physiological Chemistry,” London, 1893, vol. ii. p. 333; see also Hoppe- 
Seyler, loc. cit. 

6 Loc. cut., p. 27. 


REABSORPTION OF BILE SALTS. 391 


Cholesterin.—The amount of cholesterin in bile is very variable, 
ranging from 0°5 to 5 per cent. Cholesterin is insoluble in water or 
dilute saline solution, and is dissolved in bile by the agency of the bile 
salts, in solutions of which it is easily soluble. When the amount of bile 
salts is insufficient to hold it in solution, it slowly passes out of solution 
in a concretionary form around any particle of foreign matter present in 
the bile, or around an existing concretion forming in this manner a 
variety of gall stone. 

According to Hoppe-Seyler, cholesterin is a cleavage product, 
constantly formed in the metabolic changes of the living cell; and for 
this reason it is that cholesterin is invariably found as a chemical 
constituent of both animal and vegetable cells. Cholesterin does not 
easily undergo decomposition in the animal organism when once formed, 
and is principally excreted in the higher animals in the bile. It is 
found in increased quantity im tissue which is undergoing pathological 
change; this may, perhaps, be due to increased inability on the part of 
the cells in their vitiated condition to break up the stable cholesterin. 
Cholesterin is found in largest quantity as a constituent of the myelin 
of nerve fibres and in the blood corpuscles. 1t is probably formed most 
in the metabolism of nerve tissue, taken up by the liver cells from the 
blood, and passed as an excretion into the bile ducts. 

Cholesterin is purely an excretion, and is not reabsorbed, but passes 
out of the body with the feces. This is also the fate of the bile 
pigments, which are gradually reduced to hydrobilirubin (stercobilin) 
in their passage along the intestine. This substance may easily be 
extracted from the feces by absolute alcohol, after making acid with 
sulphuric acid. The bile pigments have a poisonous action when 
injected into a vein, which indicates that if they are reabsorbed at all 
they must be changed in the process. 

Lecithin.—The amount of lecithin present in bile is much greater 
than in any of the other secretions. All the lecithin, and any direct 
products of its decomposition to be removed from the body, are carried 
off in the bile. As lecithin, as well as cholesterin, is one of the con- 
stituents of nerve tissue, the liver, by means of the bile, may be looked 
upon as the great channel for the removal of the products of nervous 
metabolism. Lecithin is also held in solution by the bile salts. 

Reabsorption of bile salts—Their functions in the organism.— 
The bile salts differ from the other biliary constituents in that they are 
not purely an excretion. They are to a large extent reabsorbed, and 
undergo a circulation in the body, with the proba ble function of acting 
as carriers for the otherwise insoluble cholesterin in the bile. Such an 
absorption of bile salts has been shown to take place in different ways, 
which are, briefly, as follows :— 

1. Bile salts taken by the mouth, cause an increased flow of bile; 
indeed, from recent observations by various experimenters,” it seems that 
the bile salts are the only substances which truly act as cholalogues. 
This action can only be due to their absorption followed by an increased 
elimination of them by the liver. 

2. The bile of the dog contains only taurocholates. If unpaired 


1 De Bruin, Centralbl. f. klin. Med., Bonn, 1890, Bd. xi. S. 491. 

2 Baldi, Arch. ital. de biol., Turin, 1883, tome ili. p. 895; Paschkis, Schmidt's Jahrb., 
Leipzig, 1885, Bd. cevi. S. 19; Nissen, Centralbl. f. d. med. Wissensch., Berlin, 1890, Bd. 
xxvii. 8. 948. 


392 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


cholalic acid be given by the mouth, the amount of bile is increased, but 
still only taurocholates are found in the bile; but Weiss! found, after 
giving sodium glycocholate for three days (5-9 grms. per diem), that 
the bile in the gall bladder at death contained glycocholates, amounting 
to 25-30 per cent. of the total bile salts present. 

3. No connection exists between the amount of proteid metabolism 
and the amount of cholates produced, such as would be found if the 
cholates were a channel for the excretion of the nitrogen and sulphur of 
proteid decomposition products.? 

4. Tappeiner® identified bile salts in chyle obtained from the 
thoracic duct in the dog. 

5. Bidder and Schmidt * only found cholalic acid in traces in the feeces. 

A review of all these facts shows that the bile salts are not an 
excretion, but perform a circulation in the body. Besides the function 
of dissolving the cholesterin to be excreted, the bile salts are also 
credited with the effect produced by bile in aiding the absorption of 
fats.© Again, bile salts dissolve insoluble soaps of the alkaline earths. 
This may be shown by precipitating a soluble soap with calcium or 
magnesium sulphate, and then adding a solution of bile salts and gently 
warming when the precipitate dissolves.6 Maly and Emich state that 
taurocholic acid completely precipitates native proteids, but not album- 
oses or peptones.’ This in part explains the precipitation observed when 
a solution in which peptic digestion is going on (or gastric chyme) is 
mixed with bile; but part of the precipitate is doubtless mucin from 
the bile itself. The subject has been investigated by Hammarsten$ 
who found that syntonin was completely, peptone only partially, pre- 
cipitated from an acid solution in which peptic digestion of hard-boiled 
white of egg had been carried out, by the addition of bile from which 
the mucin had been removed by alcohol. Hammarsten supposes that 
the purpose of this precipitation of the semi-digested proteid, which 
must occur in natural digestion when the gastric chyme comes in 
contact with the bile, is that it may, by adhering to the intestinal wall, 
be longer subjected to intestinal digestion than it would be if it remained 
in solution. 


1 Centralbl. f. d. med. Wissensch., Berlin, 1885, Bd. xxiii. S. 121. Similar results have 
been obtained by Prévost and Binet, Compt. rend. Acad. d. sc., Paris, 1888, tome evi. p. 
1690 ; Winteler, Inaug. Diss., Dorpat, 1892. 

2 Kunkel, Arch. f. d. ges. Physiol., Bonn, 1877, Bd. xiv. S. 344 ; Spiro, Arch. f. Anat. 
wu. Physiol., Leipzig, 1880, Supp. Bd. S. 50. 

3 Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1878, Bd. lxxvii. Abth. 3. 

4 << Tie Verdauungssifte,” S. 217. 5 Vide ‘Fat Absorption,” p. 454. 

6 Neumeister, ‘* Lehrbuch d. physiol. Chem.,” Jena, 1893. 

7 Monatsh. f. Chem., Wien, 1883, Bd. iv. S. 89 ; 1885, Bd. vi. S. 95. 

8 Jahresb. ti. d. Fortschr. d. ges. Med., Erlangen, 1870, Bd. 1, S. 106. See also 
Chittenden and Cummins, 4m. Chem. Journ., Baltimore, 1885, vol. vii. p. 36; Jahresb. 
ui, d. Fortschr. d. Thier-Chem., Wiesbaden, 1885, Bd. xv. S. 319. 


DIGESTION OF CARBOHYDRATES. 393 


DIGESTION OF CARBOHYDRATES. 


The digestion of carbohydrates is brought about by the action of two 
distinct classes of enzymes, namely—1. Those which act on starches, 
producing sugars and dextrins: these are called amylolytic or diastatic 
ferments. 2. Those which act on various saccharoses, producing glu- 
coses: these are called inverting ferments. 

The two chief amylolytic ferments found in the digestive juices are 
ptyalin and amylopsin. The action of these ferments on starch may be 
demonstrated by adding to starch paste, either saliva or pancreatic juice, 
or a watery infusion of salivary or pancreatic gland. The paste very 
soon becomes quite fluid, and if the fluid be tested chemically for starch, 
it will be found that this substance is rapidly disappearing, and that a 
reducing material is being formed in continuously increasing amount in 
the solution. This testing may be done by removing a drop of the 
solution at intervals, and mixing it with a drop of a solution of iodine. 
At first the deep blue colour given by starch is obtained ; this is replaced 
after a time by a violet, this again by a red colour, and finally no 
coloration at all is obtained. If at each of these stages portions of the 
solution be tested with Fehling’s solution, it will be found that it has 
acquired reducing power, and that the amount of reduction increases 
with the length of time during which the action goes on. 

The diastase of malt is very similar in its action to both these 
ferments, but is not identical with either of them, as is shown by the 
fact that while ptyalin and amylopsin act best at body temperature, the 
optimum temperature for the action of malt diastase is about 55° C. 

Products of digestion of starch.— Whether the ferments are 
identical or not, their action, according to all observers, is the same. It 
was shown by Leube,! in 1831, that saliva dissolves starch-paste and 
forms sugar, and the same was shown for pancreatic juice by Bouchardat 
and Sandras? in 1845. It was for many years believed that the 
action of these ferments was closely analogous to that of mineral 
acids, and that the sugar produced was grape-sugar. Dextrin was 
supposed to be the first stage in the process of saccharification, and 
from the dextrin it was thought that grape-sugar was afterwards 
formed. Musculus* was the first to show that all the starch was not 
so converted into sugar, but that saccharification only proceeded until 
the solution gave no longer a colour reaction with iodine; on adding 
fresh starch-paste, the reaction recommenced and proceeded as before, 
until again all colour reaction with iodine had vanished, when, as 
before, the reaction slackened and stopped, although there remained 
plenty of dextrin in the solution. ; 


According to the earlier work of Musculus, the quantitative relationship in 
which the sugar and dextrin stand at the end of the reaction is, one part of 
sugar to two of dextrin; his later papers gave the reaction as stationary, | 
when approximately equal quantities of sugar and dextrin are present in the 
solution.* 


1 Arch. f. d. ges. Naturl., Niirnberg, 1831. 

2 Compt. rend. Acad. d. sc., Paris, 1845, tome xx. p. 1085. 

3 Journ. de pharm. et chim., Paris, 1860, Sér. 3, tome xxxvii. p. 419. 

4 Payen, Chem. Centr.-Bl., Leipzig, 1865, S. 845; Schwarzer, ibid., 1870, S. 295; 
Schulze u. Marker, ibid., 1872, S. 823. 


394 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


Still later, Sheridan Lea,! working with much more dilute solutions than 
were usually employed by other experimenters (0°4 to 4 per cent.), found as 
much as 85 per cent. of the starch converted into sugar; and by more closely 
approximating the conditions of experiment to those of natural digestion, by 
carrying out the experiment in a dialyser instead of in a glass vessel, obtained 
a still greater reduction in the percentage of dextrin formed (7 to 8 per cent.). 
He is therefore of the opinion that in the alimentary canal starch is 
completely converted into sugar before absorption. The increase in sugar 
formation, due to removal of the products of digestion, was more marked in 
working with strong than in working with dilute solutions ; this also goes to 
show that it is the accumulation of maltose in the solution which slackens and 
stops the reaction. All chemical reactions involving hydration, such as saponi- 
fication of esters, become stationary at a determinate point when a fixed 
proportion of hydration has taken place; and this point is rigorously de- 
termined by the concentration in the solution of the various factors in the 
reaction. If the substance or substances formed in the reaction be continuously 
removed from the solution, or changed in nature as they are formed, the 
reaction proceeds to completion ; but if the products of the reaction remain in 
solution unchanged, at a perfectly fixed point, dependent on the concentration 
in solution of each of the reacting substances, equilibrium is established, and 
no further change in the composition of the solution takes place. 

On the other hand, Musculus and Gruber? claim to have isolated a dextrin 
after acting on starch paste with diastase for five days, by precipitating the 
dextrin with alcohol ; on this dextrin, diastase, even in the absence of the sugar, 
has no further action. 


In 1872, O’Sullivan 3 rediscovered the sugar described by Dubrunfaut * 
as formed by the action of malt extract on starch paste, isolated it, 
investigated its properties, and named it maltose. When it was so shown 
that the sugar formed by the action of malt diastase is not grape-sugar, 
attention was directed naturally to the sugars similarly formed by the 
action of the digestive enzymes of the saliva and pancreatic juice. 
Nasse® stated that the sugar formed by the action of saliva is not 
dextrose, but another sugar of different reducing power, to which he 

gave the name of ptyalose, which, however, was not maltose, as its 
reducing power was doubled on boiling with acids, while that of maltose 
was only increased by one-half. Soon. after, v. Mering and Musculus ® 
conclusively showed that the sugar really formed both by ptyalin and 
amylopsin is identical with O’Sullivan’s maltose, and these results have 
been abundantly confirmed by subsequent observers. This result they 
established by the amount of increase of reducing power and reduction 
of rotating power, following boiling with a dilute mineral acid, as well as 
by the observation of birotation in the solution after boiling, which 
could only be due to the formation of grape-sugar. Such an analysis is 
rendered easy by the widely different specilic rotatory powers and 
reducing powers of the two sugars (see table, p. 396). 

The action of malt diastase, ptyalin, or amylopsin on starch paste 
takes place in several stages, corresponding to which more or less 


1 Journ. Physiol., Cambridge and London, 1890, vol. xi. p. 226. 
* Atschr. ifs physiol. Chem., Strassburg, 1878, Bd. ii. 8. 187. 
® Journ. Chem. Soc., London, 1872, vol. xxv. p. 579. 

4 Ann. de chim. et phys., Paris, 1847, tome xxi. p. 178. 

5 Arch. f. d. ges. Physiol., Bonn, 1877, Bd. xiv. S. 477; see also Seegen, Centradbl. f. d. 
med. Wissensch., Berlin, 1876, Ss. 851, 

6 Ztschr. f. physiol. Chem., Strassburg, 1877, Bd. i. S. 395 ; 1878, Bd. ii. S. 403. See 
also Brown and Heron, Proc. Roy. Soc. London, 1880, vol. xxx. p. 393. 


PRODUCTS OF DIGESTION OF STARCH. 395 


well-differentiated substances have been described. The first step in 
the action is, according to all observers,! the formation of soluble starch 
(amigdulin, amidulin, amidogen, or amylodextrin). This substance is 
rapidly formed, usually in one or two minutes; it gives the same blue 
reaction with iodine as raw starch or starch paste, and is precipitated by 
tannic acid, by which it is distinguished from the dextrins formed in the 
subsequent stages. 

In the second stage, this soluble starch is decomposed into a sub- 
stance giving a red colour with iodine and maltose. The substance 
giving the red colour now gets the name given by Briicke of erythro- 
dextrin; it corresponds to Nasse’s dextrin, Griessmayer’s dextrin-1 
and Bondonneau’s dextrin-«. 

In the third stage, this erythrodextrin is split up into a dextrin (or 
several dextrins), giving no coloration with iodine, and hence called 
achroddextrin, and a further quantity of maltose. Finally, according to 
some, a part of this achroddextrin breaks up, yielding more maltose, 
and a variety of achroddextrin, altogether unaffected by diastatic 
ferments, which with the maltose split off at different stages from the 
intermediate products, forms the final product of the reaction, no matter 
how long prolonged. 

These successive changes may be represented as in the following 


scheme :— 
Starch 


Soluble Starch 
| 


| | 
Erythrodextrin Maltose 


Achroddextrin Maltose 


All observers are agreed as to the existence of soluble starch, and 
practically all as to that of erythrodextrin, although Musculus and Meyer? 
state that, on carefully mixing dextrin stained with iodine, with soluble 
starch stained with iodine, they obtained the colour of erythrodextrin, and 
conclude that what has been called erythrodextrin is probably such a mixed 
colour. This result has not been confirmed by other observers; still it 
should be borne in mind that a pure substance has not yet been isolated, and 
that at present erythrodextrin is only a name given to a substance supposed 
to exist, because of a red colour which is obtained at a certain stage in the 
digestion of starch by diastatic enzymes. The material which is found later 
in the process, which is not a sugar and gives no coloration with iodine, has 
been called achroddextrin, but it has none of the constant properties of a 
pure simple substance, and is probably a mixture of several substances 
(achroddextrins), though as yet none of these have been properly isolated. 

Musculus and Gruber,® working on starch solutions with dilute acids and 
with diastase, differentiated, according to varying conditions of temperature, 
amount of diastase added, and length of time of action of the ferment, three 
achroddextrins (a, 8, and y), possessing, according to these observers, different 


1 Nasse, Arch. f. d. ges. Physiol., Bonn, 1877, Bd. xiv. S. 474; Griessmayer, Chem. 
Centr.-Bl., Leipzig, 1871, S. 636; Briicke, ‘‘ Vorlesungen,” and Sitzwngsb. d. k. Akad. d. 
Wissensch., Wien, 1872, Abth. 3; Bondonneau, Compt. rend. Acad. d. Se., Paris, 1875, 
Eee lxxxi. pp. 972, 1210; Musculus, Zéschr. f. physiol. Chem., Strassburg, 1878, Bd. il. 

ak ivi 
2 Ztschr. f. physiol. Chem., Strassburg, 1880, Bd. iv. S. 451. 
3 Tbid., 1878, Bd. ii. S. 177. 


396 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


specific rotatory powers and reduction coefficients; but they scarcely give 
adequate proofs that they are describing pure substances.! They found that 
even after twelve months a portion of the dextrin remained unconverted into 
maltose, and the substance so remaining was unfermentable by yeast. This 
substance is y-achroddextrin, and is formed together with some maltose by the 
splitting up of -achroddextrin, which in its turn is formed by a similar 
decomposition of a-achroddextrin. 
The following is a summary of their results :— 


| 


Relative reducing é 2 
'Sp. Rotatory Power. | Power for Fehling’s wage sre 
| Solution. ars © 
| Soluble starch . : : : 218° 6 Reddish blue. 
Erythrodextrin : at ete le | Red. 
z-Achroodextrin : 2 3 210° 12 ' No coloration. 
B 55 ; : ‘ sl 190° 12 Rs 
y ni 150° 28 io 
Maltose ; k a 150° 66 i 
Grape-sugar. ‘ : | 50° 100 a 
| 


The digestion of starch by diastatic enzymes consists of a breaking 
up, through several more or less well-defined stages, by a process of 
gradual hydrolysis, of a very complex molecule into a much simpler one, 
and might be represented schematically by the following general 
equation, which cannot be made more definite, because we are un- 
acquainted with the molecular weights of starch and dextrin, only 
knowing that they are very large— 


Starch Maltose Dextrin 
(CH. 103) + (HO) = 3(CigHss0 1,0) +2=" (CHO), 


5) 
That is, starch and water, in presence of a suitable ferment, yield 
maltose and different dextrins, but we are ignorant of the value of 
n, m, and p. 


Attempts to carry too far the analogy between the action of | 
dilute mineral acids and that of the diastatic ferments on starch, 


led, as already stated, to an error, which persisted for several years, 
as to the products of the latter action. Nevertheless, a close analogy 
does exist between the two processes; both are essentially hydration 
processes; and in both the same stages may be observed. They 
only differ im two respects, first, that the dilute acid at boiling tem- 
perature acts much more rapidly; secondly, that it proceeds a 
stage further, and very rapidly converts the maltose formed into grape- 
sugar. 

These successive changes may be best observed by boiling with very 
dilute acid (‘2 per cent. or less). Soluble starch is first formed, giving, on 
neutralisation, a blue with iodine; next, is an intermediate stage, in which a 


violet is obtained followed by a stage giving a red colour (erythrodextrin) ; 


and finally a stage is reached at which a coloration is no longer obtained 


1 According to Brown and Morris (see Trans. Chem. Soc., London, 1885, p. 527 ; 1889, 
p- 462), the chemical and physical properties of these different achroddextrins might be 
given by a variable mixture of one achroddextrin possessing no reducing power with mal- 
tose. They admit the existence besides achroddextrin, of maltodextrin (Herzfeid), a body 
intermediate between achroddextrin and maltose, but more nearly allied to the latter. 


ee, 


‘ee 


PRODUCTS OF DIGESTION OF STARCH. 397 


(achroddextrin). If, when this stage is reached, the solution is rapidly 
cooled and neutralise d,a little maltose can be ¢ separated from accompany- 
ing dextrose, showing that maltose is here also formed, but is con- 
verted rapidly into grape-sugar. 

Although maltose is the chief sugar formed in the action of both 
ptyalin and amylopsin upon starch, yet a trace of grape-sugar is also 
formed.t The quantity of grape-sugar formed is in both cases small, but 
is greater in the case of the pancreatic ferment. It has recently been 
discovered that in both salivary and pancreatic digestion, besides 
maltose and small quantities of grape-sugar, another sugar, isomaltose? 
is formed, in considerable quantity. The relative quantity of the three 
sugars varies with the quantity of ferment present, and the duration of 
the experiment. A weak ferment and short time of action favour the 
formation of isomaltose; by much ferment and prolonged action large 
quantities of maltose are produced, accompanied by traces of dextrose? 
It is stated that traces of an inverting ferment are present, both in the 
salivary and pancreatic glands, especially the latter; and it is possible 
that the traces of dextrose formed may be due to the action of these on 
the maltose and isomaltose first formed. 

The action of the amylolytic enzymes on glycogen is precisely similar 
to their action on starch; dextrin, maltose, and isomaltose being formed 
in very much the same proportions.+ 

The production of maltose by the diastatic ferments is not the end 
of the digestion of amyloses; there is evidence that maltose never 
reaches the systemic circulation. I it be injected intravenously it is soon 
discoverable in the urine ;° this shows that in digestion it is inverted, 
either before it is absorbed, or after absorption and before reaching the 
systemic circulation. 

This further process of hydrolysis may be to some extent carried out, 
so far at least as concerns that portion of maltose arismg from 
salivary digestion, by the hydrochloric acid of the gastric secretion, but it 
is mainly brought about by an inverting ferment, discovered by Brown 
and Heron in the mucous membrane of “the small intestine, and also in 
the succus entericus.® 

The succus entericus (as well as the intestinal mucous membrane and 
glycerin or water extracts of it) possesses only a feeble diastatic action 


'Musculus and Gruber, Zéschr. f. physiol. Chem., Strassburg, 1878, Bd. ii. S. 177 ; 
Musculus and von Mering, ibid., 1878, Bd. ti. S. 408 ; von Mering, ibid., 1881, "Ba. v. 8. 
185 ; Brown and Heron, Ann. d. Chem., Leipzig, 1879, Bd. excix. S. 165 ; 1880, Bd. eclv. S. 
228 ; Proc. Roy. Soc. London, 1880, p. 393. 

2 Kiilz u. Vogel, Zischr. f. Biol., Miinchen, 1894, Bd. xxxi. S. 108. The existence of 
isomaltose is, however, denied by Brown and Morris (Z'rans. Chem. Soc., London, 1895, vol. 
lxvii. p. 737), who state that it is a mixture of maltose and dextrins. 

3 Journ. Physiol., Cambridge and London, vol. xv.; Abelous, Compt. rend. Soc. de biol., 
Paris, 1891. 

4Hensen, Verhandl. d. phys.-med. Gesellsch. zu Wiirzburg, 1856, Bd. vii. S. 219 ; 
Virchow’s Archiv, 1857, Bd. xi. S. 395; Claude Bernard, Gaz. méd. de Paris, 1857, No. 13; 
J. Seegen, Centralbl. f. d. med. Wissensch., Berlin, 1876, S. 849; Arch. f. d. ges. Physiol., 
Bonn, 1879, Bd. xix. 8. 106; Kiilz u. Vogel, Zischr. f. Biol., Miinchen, 1894, Bd. xxxi. 
S. 108. 

> Bimmermann, Arch. f. d. ges. Physiol., Bonn, 1879, Bd. xx. S. 201; Philips, 
Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1881, Bd. xi. S. 60 ; Dastre et Bour- 
quelot, Compt. rend. Acad. d. sc., Paris, 1884, tome xeviii. p. 1604; Bourquelot, Journ. de 
Vanat. et physiol., etc., Paris, 1886, tome xxi. p. 161. 

6 Brown and Heron, Proc. Roy. Soc. London, 1880, p. 393; Ann. d. Chem., Leipzig, 
1880, Bd. cciv. S. 228; Vella, Untersuch. z. Naturl. d. Mensch. u. d. Thiere, 1881, Bd. 
xiii. S. 40; Bourquelot, Compt. rend. Acad. d. sc., Paris, 1883, tome xcyii. p. 1000. 


398 CHEMISTRYVOF THE DIGESTIVE PROCESSES. 


on starch but has a remarkable power in converting maltose into ~ 
grape-sugar. Brown and Heron surmised from this that maltose 
would be found to be a non-assimilable substance; unknown to them, 
Bimmermann had already shown this to be the case, and many subse- 
quent observers have confirmed the result. 

Digestion of cane-sugar.—Cane-sugar resembles maltose in not 
being directly assimilable from the blood; after intravenous injection it 
is excreted by the kidneys. In the course of digestion it is either com- 
pletely inverted while in the alimentary canal, or may in part be so 
changed in its passage through the absorbing cells of the mucous 
membrane. 

Some cane-sugar is inverted in the stomach, probably by the action 
of the hydrochloric acid there present.2, Lehmann ® repeatedly found, in 
the stomach and duodenum of rabbits fed on beetroot, invert-sugar only. 
Seegen found that, after feeding dogs on cane-sugar, the stomach always 
contained a small amount of a reducing sugar along with a great deal of 
unchanged cane-sugar; and that the small intestine contained no sugar. 
He argues from this, that all the cane- sugar is inverted in the stomach, 
the invert-sugar being there absorbed as fast as it is produced. 
It is probable, however, from the work of other observers, that a con- 
siderable part of the inversion takes place in the small intestine by the 
action of the intestinal juice, and it may be also by the direct action 
of the cells of the intestinal mucous membrane. 

Watery infusions of the mucous membrane from any part of the 
small intestine are capable of inverting cane-sugar,t and the same 
power is possessed by the intestinal contents in animals which have 
been killed during active digestion.® The intestinal juice obtaimed by 
Vella® from fistule almost instantly inverted cane-sugar, and a strong 
inverting action of pure succus entericus has been observed by many 
others. 

The inversion of the saccharoses by the intestinal juice is brought 
about by enzymic action, but very little is known of the enzyme 
or enzymes involved. It was supposed by Hoppe-Seyler and Thier- 
felder? that the inversion might be due to bacterial action or to 
inverting enzymes taken in with the carbohydrate food, but the former 

1 A diastatic action on starch was found by Schiff, Jahresb. ii. d. Fortschr. d. ges. Med., 
Erlangen, 1867, Bd. i. S. 155; Kichhorst, Jahresb. ii. d. Fortschr. d. Thier-Chem., 
Wiesbaden, 1871, Bd. i. 8. 198; Paschutin, ibid., S. 304; Ewald, Virchow’s Archiv, 1879, 
Bd. lxxv. 8S. 409; Garland and Masloft, Untersuch. a. d. physiol. Inst. d. Univ. Heidelberg, 
1878, Bd. ii. S. 290; Brown and Heron, Joc. cit.; Dana, Med. News, Phila., 1882, vol. xli. 
p- 59.; Hamburger, Arch. f. d. ges. Physiol., Bonn, 1895, Bd. Ix. S. 560; Mendel, zbid., 
1896, Bd. Ixiii. S. 425. On the other hand, its existence is denied by Thiry and by Leube, 
Jahresb. %. d. Fortschr. d. ges. Med., Evlangen, 1868, Bd. i. S. 97. It must be remembered 
that the diastatic action is admittedly a slight one by most of those observers who confirm 
it, and that most organs and tissues possess a slight diastatic action, so that it is difficult to 
be certain that the intestinal mucous membrane ‘specifically secretes a diastatic ferment. 

* It is certain, from purely chemical experiments. that the acid is capable of producing such 
an effect, and no inverting enzyme has. ever been shown to exist in the gastric secretion. 

3 Tehrbuch der phy siol Chem. < Aufl22: Bdseiliea S250 reve “Becker, Ztschr. f. 
wissensch. Zoologie, Bd. v. 8. 123; J. Seegen, Arch. f. d. ges. Physiol., Bonn, 1887, Bd. xl. 


S. 41. 

4 Paschutin, Arch. f. Anat. wu. Physiol., Leipzig, 1871, 8. 306. 

5 Claude Bernard, ‘‘ Lecons sur la diabete et la glycogenese animale,” Paris, 1877, 
257-261. 

6 Untersuch. z Naturl. d. Mensch. u. d. Thiere, 1889, Bd. xiii. S. 62; see also 
Bastianelli, zbid., 1886, Bd. xiv. S. 146. 

7 “¢Handbuch der. path. u. physiol. chem. Analyse,” 1893, Aufl. 6, 8. 298. See also 
Pautz and Vogel, Ztschr. f. biol., Miinchen, 1895, Bd. xxxii. S. 304. 


DIGESTION OF PROTEIDS. 399 


supposition is negatived by the rapidity of the action, and its progress 
in presence of antiseptics ; and both by the recent observations of 
Miura, which show that the mucous membrane of the intestine of 
newly-born animals, under antiseptic conditions, causes inversion. No 
inversion was obtained with the mucous membrane of the stomach or 
large intestine. 

Brown and Heron? have shown that the dried mucous membrane 
of the small intestine is much more powerful, both in its diastatic action 
on starch and in its inverting action on cane-sugar and maltose, than 
are infusions of the same material. Starch also disappears from an 
intestinal fistula (Thiry) much more rapidly than it is possible for the 
succus entericus,® judging from other experiments, to convert it into 
sugar. These facts point to a possibility that the epithelial cells of 
the intestinal mucous membrane may possess the power of absorbing 
starches and saccharoses, and submitting them to diastatic and inver ting 
processes, in passing them on to the lymph spaces of the villi; that, in 
fact, cellular digestion of absorbed carbohydrates may take place in the 
epithelial cells after absorption. 

The secretion of the small intestine is generally stated to be 
inactive towards lactose, so that the inversion “of this sugar probably 
occurs after its absorption by the columnar cells. 


Human succus entericus has been investigated by Ewald,® by Demant,® 
and by Tubby and Manning ;’ they all agree as to its diastatic action on starch 
and inverting action on cane-sugar. Tubby and Manning also tested its action 
on maltose, and found that this was converted into dextrose. The ferment or 
inverting material adhered to mucus whenever a precipitation of this took 
place in the fluid, so that the mucus was more effective than the clear 


fluid.§ 


DIGESTION OF PROTEIDS. 


The digestion of proteids is a much more complex process than that of 
either the fats or carbohydrates, and one of which our knowledge is still 
less exact. In the digestion of carbohydrates we are absolutely certain 
that we have to do with a hydrolytic process, and that from a body 
of absolutely fixed percentage com position, though often of unknown 
molecular weight, there is produced in digestion a substance of known 
formula, and to a certain extent of known structure. In proteid digestion, 
while it is probable that a very similar action is taking place, we have 
no such certainty. The digestive process begins with material, the 
different proteids, which varies considerably in percentage composition. 


1 Ztschr. f. Biol., Miinchen, 1895, Bd. xxxii. S. 266. 

2 Proc. Roy. Soc. London, 1880, vol. xxx. p. 399. See also Shore and Tebb, Journ. 
Physiol., Cambridge and London, 1892, vol. xiii. (Proc. Physiol. Soc.), and M. C. Tebb, ibid. 
vol. xv. p. 421. 

3 Rohmann, Arch. f. d. ges. Physiol., Bonn, 1887, Bd. xli. S. 424. 

4 Meyer, ‘ Die Lehre von den chemischen Fermenten, ” 1882; Dastre, Arch. de physiol. 
norm. et path., Paris, 1890, tome xxii. p. 103 ; C. Voit and Lusk, Zéschr. 7. Biol., Miinchen, 
1891, Bd. xxviii. S. 275; ‘Mendel, Arch. f. d. ges. Physiol., Bonn, 1896, ta Ixiii. S. 425. 
See, however, Pautz and Vogel, Ztschr. J. Biol., Miinchen, 1895, Bd. xxxii. 8. 304; Rohmann 
u. Lappe, Ber. d. deutsch. chem. Gesellsch., Berlin, 1895, Bd. XXViii. Ss. 3506. 

° Virchow’s Archiv, 1879, Bd. lxxy. S. 409. 6 Thid., S. 490. 

* Guy's Hosp. Rep., London, 1891, vol. xlviii. p. 271; Centralbl. f. d. med. Wissensch., 
Berlin, 1892, S. 945. 

8 Paschutin (Joc. cit.) found that the inverting enzyme was mechanically precipitated 
along with collodion. 


400 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


From this variable material products showing minute variations are 
produced, of which we only know that they are more soluble than the 
mother substance, less easily thrown out of solution by various precipit- 
ants, and to a certain slight extent are capable of diffusing through 
membranes. 

Here our knowledge at present stops. In spite of most laborious 
researches on the subject by a host of observers, we know no more of 
the structure of any save the final decomposition products of proteid 
digestion than we do of the proteids themselves. Certain products have 
been isolated at various intervals in the progress of digestion of proteids, 
which show that the process gives rise to several intermediate bodies, 
ever increasing in solubility towards precipitants as they are formed 
nearer the end of the process; and it may be—it is a probable inference 
from analogy —that these substances are ‘simpler than the proteids from 
which they originate, but as yet the simplest of them is too complex 
for our fr agmentary knowledge to give any indication of its structure. 
Nor is there any know ledge of the relationship of these several stages of 
proteid digestion to one another. 


It is very probable that the process of proteid digestion, like all the 
other digestiv e processes, 1s one of continuous absorption of the elements of 
water or hydrolysis. 

This is shown by the following observations :—(1) One of the commonest 
agents employed in organic chemistry for the purpose of hydrolysing a 
substance is boiling with a dilute mineral acid, or subjecting in closed 
vessels to the action of superheated steam. On submitting proteids to the 
prolonged action of these reagents, products closely resembling or identical 
with those produced by the action ‘of the proteolytic enzymes are obtained. 
(2) A small but decided increase in weight has been observed in the formation 
of peptone from proteid.t (3) Peptones can be converted artificially back 
into proteids by the use of reagents which are essentially dehydrating in 
their action. If fibrin-peptone be heated for an hour with acetic anhydride, 
the excess of anydride distilled off along with acetic acid formed in the pro- 
cess, and the residue treated with hot water, the greater part of it dissolves. 
When this solution is dialysed, there remains behind in the dialyser a solution 
which coagulates on boiling, and is precipitable by nitric acid or potassium 
ferrocyanide. Also, peptone heated for some time to 140° C. yields a substance 
which on solution in water shows more of the properties of a native albumin 
than of a peptone.” 

Other theories regarding the digestion of proteids are—(1) That the proteids 
are polymers of the peptones, and that the process of digestion is a process of 
depolymerisation,® (2) that proteids and peptones are simply different isomeric 
forms of the same substance, and (3) the micellar theory,*+ according to which 
the proteids are composed of micelli, which are a kind of second order of 
molecule much more complex in structure. On peptonisation, the proteid first 
breaks up into its constituent micelli, then the micelli fall into molecules, in 
the chemical sense of the word, and these molecules are the peptone molecules. 


1A. Danilewski, Centraib/. f. d. med. Wissensch., Berlin, 1880, No. 42, S. 769. 

? Henninger, Compt. rend. Acad. d. sc., Paris, 1878, tome lxxxvi. p. 1464; Hofmeister, 
Zischr. f. physioi. Chem., Strassburg, 1878, Bd. ii. S. 206; Neumeister, Zéschr. f. Biol., 
Miinchen, 1887, Bd. xxiii. 8S. 394. 

8 Maly, Arch. f. d. ges. Physiol., Bonn, 1874, Bd. ix. S. 585; dbid., 1879, Bd. xx. 
S. 315; Herth, Ztschr. f. physiol. Chem., Strassburg, Bd. i. S. 277 ; Monatsh. f. Chem., 
Wien, Bd. v.; Poehl, Ber. d. deutsch. chem. Gesellsch., Berlin, 1881, S. 1355 ; 1883, S. 
1152; Loew, Arch. f. d. ges. Physiol., Bonn, 1883, Bd. xxxi. 8. 393. 

4 Griessmayer, Jahresb. ti. d. Fortschr. d. Thier-Chem., Wiesbaden, Bd. xiv. S. 26. 


PEPTIC DIGESTION OF PROTEIDS. 401 


Ultimate chemical analysis shows that the composition of the peptones 
and albumoses is practically the same as that of the proteids from which they 
are formed ; in some cases the proteids show a somewhat higher percentage of 
carbon and ‘lower of hydrogen and oxygen than the proteids ‘of their digestion, 
in others the reverse, but in no cases any very considerable variation. So 
that, if the process of peptonisation is one of hydrolysis, the peptone molecule 
must be out of all proportion greater than that of the molecule of water. 
Nevertheless the hydrolytic theory is the one most generally received, and 
against this unfavourable argument from analytical results must be set the 
other experiments already quoted. 


The main differences between the proteids and peptones of physio- 
logical importance are the physical ones, that the latter are much more 
soluble, and are diffusible, though with difficulty, through membranes. 
It is indeed purely by physical means that we at present differentiate 
proteids and peptones and the intermediate products between them, 
and not by any well-marked chemical differences shown by them. The 
different proteids, albumoses, and peptones are classified and marked 
off from one another almost entirely by the behaviour of their solutions 
towards solutions of neutral salts of different strength, according to 
whether these dissolve or precipitate them. It is questionable whether 
it is justifiable on such a slender basis to assume, as is commonly done 
that these precipitates correspond to pure compounds. It ought to be 
remembered that these names at present only apply to certain precipi- 
tates, and that it is not at all known whether these represent distinct 
chemical substances, nor indeed what they do represent. Still less right 
have we to assume from mere proteid analyses that the products of 
digestion of different proteids yield substances distinctive of them and 
worthy of distinctive names. 

The two proteolytic enzymes, pepsin and trypsin, closely resemble 
each other in their action on proteids, a series of very similar products 
being in each case evolved, which, generally speaking, become more 
soluble and probably simpler i in constitution as the end of the process is 
approached. Still there is sufficient difference to warrant a separate 
consideration of the two processes. 


Peptic DIGESTION OF PROTEIDS. 


The stomach was recognised even by the ancients as a digestive 
organ, and its action attributed in many cases to the “animal heat” 
assisted by mechanical force. Digestion seems to have been first con- 
sidered as a similar process to fermentation by van Helmont, and this 
view was also maintained by Sylvius. 

Réaumur! seems to have been the first to experiment on gastric 
digestion. He carried out his successful experiments on a tame buzzard, 
which, like some other birds of prey, regurgitates after a time the more 
indigestible portions of its food. He administered various kinds of 
food, enclosed in small metallic tubes closed at one end and covered by 
muslin at the other, so as to prevent any mechanical action of the 
gizzard and yet allow the gastric juice to act; he found that meat was 
digested in the course of some hours, and in a shorter period was digested 
partially on the outside while the interior still remained untouched. 
Réaumur also obtained gastric juice by enclosing pieces of sponge in 

1 «¢ Hist. Acad. roy. d. sc. de Paris,” 1752, pp. 266, 461. 
VOL, 1.—26 


402 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


such tubes, but could not get it to act outside the body. Similar ex- 
periments were carried out by Stevens! of Edinburgh, who availed him- 
self of the services of a juggler possessing a trick of swallowing stones 
and regurgitating them. This man he gave to swallow some hollow 
silver balls which were perforated with holes; the balls were screwed 
together in two halves and could be filled with meat. He found that 
the meat was rapidly dissolved and disappeared. To Stevens also belongs 
the credit of being the first to observe digestion outside the body. He 
obtained gastric juice from a dog’s stomach, and found that when a piece 
of meat was subjected to its action in a warm place it became dissolved 
in about eight hours. 

Soon afterwards Spallanzani confirmed these experiments, and 
showed conclusively that, under favourable conditions, the juice acted 
outside the body, and also that it had a marked action in preventing 
putrefaction. 

Between 1825 and 1835 Beaumont published his classical observa- 
tions on Alexis St. Martin. In 1834, Eberle? discovered a method of 
preparing an artificial gastric juice, which possessed all the digestive 
properties of the normal secretion, by acting on the gastric mucous 
membrane with dilute hy drochloric acid. Schwann? in 1836 gave the 
name pepsin to the active principle to which he supposed the gastric 
juice owed its activity. 

Products of peptic digestion.—The first exact investigations into 
the nature of the products of gastric digestion are those of Meissner # 
and his pupils. After digestion in acid solution and filtration, a pre- 
cipitate was obtained on “nearly neutralising, to which the name of 
parapeptone was given. 


There is a considerable difference of opinion among various authors as to 


what this parapeptone of Meissner is represented by in our more modern nomen- 
clature. By some it is stated to have been syntonin. If Meissner had used a 
strongly peptic digestive medium, filtered and neutralised, just after the bulk 
of the proteid was ‘dissolved, he would undoubtedly have obtained syntonin or 
acid albumin; but from his description it is evident that he was dealing 
with a substance afterwards discovered by Kiihne, and renamed antialbumate. 
This substance seems by its behaviour to be indeed a close ally of acid 
albumin, and is obtained most readily by a more prolonged action of dilute 
acids at 40° C. than is necessary to form acid albumin. It is also formed to 
a small extent in a weak peptic digestive medium, probably from a similar 
cause. Like acid (or alkali) albumin, it is insoluble in water, but easily 
soluble in even very dilute acids or alkalies ; but it differs from acid albumin 
in that when once formed it is not attacked by any pepsin in acid solution 
by which acid albumin is actively peptonised. It is, however, convertible into 
peptone (antipeptone) by the action of pancreatic juice, no leucine or tyresine 
being simultaneously formed. Meissner was undoubtedly using very weak 
solutions of pepsin, and the action he obtained approximated to the prolonged 
action of weak acids alone at 40° C. The action of the pepsin present was 
too weak to catch, as it were, all the acid albumin on its way into antialbumate 
and peptonise it ; and when once any antialbumate was formed, it could not then 
be attacked and peptonised. Meissner’s product was thus almost purely anti- 


1 “De alimentorum concoctione,” Edin., 1777. 
2 «Physiol. d. Verdauung nach ‘Versuch.,” W Viirzburg, 1834. 

3 Arch. f. Anat. , Physiol. u. wissensch. Med., 1836, S. 90. 

4 Zischr. f. rat. "Med., 1859-1862, Dritte Reihe, Bd. vii. 8. 1 + Vill. 9:1 280) 5) ee 
xii. S. 46; xiv. S, 303. Reviewed in Biol. Centralbl., Erlangen, 1884, Bd. iv. 8. 
407, 


FRODUCTS OF PEPTIC DIGESTION, 403 


albumate. If he had used a slightly stronger solution for a somewhat shorter 
time, he would have obtained a mixture which would have been partially 
peptonised and partially remained unchanged when subjected to the action 
afterwards of strong fresh pepsin and acid ; if he had used a strongly peptic 
solution for a much shorter time, the result would have been purely acid 
albumin and no antialbumate whatever; giving with fresh pepsin, or more 
prolonged action, complete peptonisation. 


On the addition of acid to the almost neutral faintly acid solution, a 
further precipitate formed, which Meissner regarded as a different sub- 
stance, and called metapeptone. It was insoluble in very dilute acids (0-1 
per cent.), soluble in stronger acids. A third residue obtained in the diges- 
tion of casei or fibrin he called dyspeptone ; this was insoluble in dilute 
acids (2 per cent. HCl), but soluble in dilute alkalies and in stronger 
acids. This substance was probably a mixture of nucleins, with the sub- 
stance subsequently described by Kiihne as antialbumid.! 

After the removal of these neutralisation products, various other 
substances were still left in solution; these Meissner classed together 
as peptones, distinguishing— 


a-peptone, precipitable by concentrated nitric acid, as well as by potassium 
ferrocyanide and dilute acetic acid. 

B-peptone, not precipitated by nitric acid, but by potassium ferrocyanide 
and strong acetic acid. 

y-peptone, not precipitated either by nitric acid or by potassium ferro- 
eyanide and acetic acid. 

Of these three substances only y-peptone corresponds to the present-day 
definition of a peptone; the others were probably different albumoses. 


A valuable side-light was thrown on the digestion products of 
proteids by Schiitzenberger’s? researches on the prolonged action of 
acids and alkalies at high temperatures on these substances. It has 
already been indicated that peptonisation is the result obtained, 
followed finally by a splitting up into amido-acids. 


Superheated steam possesses a similar peptonising action on proteids, and 
yields by prolonged action the usual amido-acids.* According to Neumeister,* 
the intermediate substances produced are, however, somewhat different, the 
substance first formed lies intermediate between the coagulable proteids and 
the albumoses. It is not coagulated by boiling, but in its behaviour towards the 
usual precipitants behaves like a coagulable proteid ; this substance is termed 
atmidalbumin. By further hydration it yields a true albumose, which, however, 
differs somewhat in its properties from any of the albumoses naturally formed 
in digestion, and has been named atmidalbumose. Both atmidalbumin and 
atmidalbumose are precipitated by dilute acids, and are converted by boiling 
with dilute sulphuric acid into deutero-albumose. Similar products are pro- 
duced by the action of the vegetable digestive ferment papoyotin or papain, 
and are in the end, by the prolonged action of this ferment, converted into 
amido-acids.° 


1 See p. 406. 

* Bull. Soc. chim., Paris, 1875, tome xxiii. pp. 161, 193, 216, 242, 385, 433 ; xxiv. pp. 
2, 145; Jahresh. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1875, Bd. v. S. 299. 
Schiitzenberger’s researches are referred to at length in the article on the ‘‘ Chemical Con- 
stituents of the Body,” pp. 30-32 of this volume. 

® Lubavin, Hoppe-Seyler’s Med.-chem. Untersuch., Berlin, 1871, S. 480 ; Krukenberg, 
Sittzungsb. d. Jenaisch. Gesellsch. f. Med. wu. Naturw., 1886. 

4 Zischr. f. Biol. Miimchen, 1890, Bd. xxvi. S. 57. 

° Sidney Martin, Jowrn. Physiol., Cambridge and London, 1885, vol. vi. p. 336, 


404. CHEMISTRY OF THE DIGESTIVE PROCESSES. 


Meissner’s views as to the decomposition of proteids on digestion 
did not at first obtain much credence. The formation of a substance 
precipitated by neutralisation, and incapable of further conversion by 
pepsin and an acid in the course of normal digestion, was denied, and 
with right, by Briicke and others. 

Briicke! stated that there was no such decomposition of the pro- 
teid molecule as Meissner indicated, but that fibrin is first dissolved 
and afterwards converted in great part into acid albumin, accom- 
panied even at first by peptone in small quantity. If neutralisation 

takes place at this stage, a heavy precipitation is the result, and there 
remains in solution a small quantity of coagulable proteid (formed by 
the solution of the fibrin and not yet converted into acid albumin by 
the acid) mixed with albumoses and peptone. If, however, peptic 
digestion be allowed to proceed to completion, no precipitation occurs 
on neutralising, and the solution contains only albumoses and peptones. 
This shows that Meissner’s parapeptone, as W ell as Kiihne’s antialbumate 
and antialbumid, which will be described later? are not formed to any 
extent in active peptic digestion, but are merely products of prolonged 
action of dilute acid. 


In order to study the products formed in peptic digestion, it is necessary 
to proceed with a digestive fluid which has been purified from products of 
digestion, due to self-digestion or otherwise, by one of the methods already 
described,* or else to take advantage of a peculiar property possessed by 
fibrin, and in a lesser degree by some other forms of proteid, of absorbing 
pepsin from solution.* 

Any digestive fluid containing pepsin (such as that obtained by auto- 
digestion of pig’s gastric mucous membrane in dilute hydrochloric acid) is 
carefully neutralised, using powdered chalk for the purpose, so as to avoid all 
danger of alkalinity, by which the pepsin would be rapidly destroyed.® After 
neutralising and filtering, the fluid is shaken up with flakes of fibrin for 
some time ; this is best done by blowing a stream of air through the mixture, 
placed in a tall vessel, by means of a Bunsen filter pump. In about an hour 
the fibrin becomes impregnated with pepsin, which, however, cannot attack it 
in the neutral fluid. So firmly adherent is the enzyme to the fibrin, that the 
latter may be freely washed without parting from it. If this fibrin be now 
placed in dilute hydrochloric acid (-2 per cent.) at 40° C., it is quickly dis- 
solved and digested. Instead of neutralising the impure digestive fluid, it 

may be saturated with sodium chloride, which stops the digestive action of the 
pepsin ; on now agitating thoroughly for about an hour, the fibrin is saturated 
with pepsin, after which it may ‘be washed as before. This peculiar power of 
absorbing pepsin is shown in a varying degree by all solid forms of proteid. 
Fibrin possesses it most markedly, muscle fibre and casein also show it well, 
but coagulated proteids show it comparatively much more feebly.® 


Fibrin, or other solid proteid, on digestion, swells up, dissolves, and 
is converted into syntonin or acid albumin. The same result is obtained 


1 Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1859, Bd. xxxvii. S. 181; 1861, Bd. xliii. 
S. 601. 

2 See pp. 406-409. 3 See p. 402. 

4Von Wittich, Arch. f. d. ges. Physiol., Bonn, 1872, Bd. v. S. 448; K. Mann, ‘‘ Ueber 
die Absorption der proteolytischen Enzyme durch die Eiweisskérper,” Inaug. Diss., 
Wiirzburg, 1892, S. 23. 

5 Langley, Jowrn. Physiol., Cambridge and London, 1882, vol. iii. p. 253. 

6 Wurtz, Compt. rend. Acad. d. sc., Paris, 1881, tome xciii. p. 1104; A. Fick, 
Sitzungsb. d. phys.-med, Gesellsch. zu Wiirzbur Ds 1889, S. 23; K. Mann, Inaug. Diss., 
Wiirzburg, 1892. 


* 


CLEAVAGE THEORY OF PROTEID DIGESTION. 405 


with acid alone, but incomparably more slowly. The acid and ferment 
seem to mutually assist each other. Pepsin alone is inactive, the acid 
alone acts with extreme slowness, but in the presence of the acid the 
ferment speedily dissolves the proteid, which is then rapidly attacked by 
the acid and converted into acid albumin. 


When the proteid undergoing digestion is fresh fibrin which has not been 
previously subjected to heat coagulation, a body possessing the properties of 
a globulin is found in the solution in the first stage of digestion, before or 
just when complete solution has taken place; a similar body is also said to be 
formed in small quantity as a first product of digestion of other forms of 
proteid.! In a recent paper it is stated by Arthus and Huber? that this 
globulin is simply dissolved fibrin. These authors found such a body co- 
agulating at 56° C. on digesting unboiled fibrin; but boiled fibrin yielded no 
such product. They also determined that ‘“‘ Witte’s Peptone ” dissolved un- 


boiled fibrin, at 40° C., giving a solution which coagulated on heating at 
56°, 68°, and 75° C 


The acid albumin is next attacked by the pepsin and further 
altered, giving rise to a number of substances called a/bumoses, proteoses, 
or propeptones, and these in turn are slowly and incompletely con- 
verted into peptones. Here the action of pepsin ceases. 

Cleavage theory of proteid digestion.—The cen theory of 
proteid digestion was first enunciated by Kiihne in 1877.2 He describes 
the digestion of albumins by trypsin as taking place in two stages: in 
the first stage the albumin is changed into peptone (amphopeptone) ; 
in the second stage, one-half of this peptone (hemipeptone) is further 
changed, while the other half (antipeptone) remains unaltered. Peptic 
digestion i is not essentially different from the first stage of tryptic, and 
while it is not possible to obtain two bodies from pepsin peptone, still it 
is probable that this substance is a mixture of two bodies, antipeptone 
and hemipeptone, as is also the case after the first stage of tryptic 
digestion. 

Unable to isolate two bodies from the end products of peptic 
digestion, one of which should remain unchanged when subjected to 
tryptic digestion, while the other broke up under like treatment into 
leucine and tyrosine, Kiihne surmised that the cleavage might take 
place earlier in the process of peptic digestion, and that more success 
might attend an attempt to separate the precursors of anti- and hemi- 
peptone, namely, the corresponding albumoses, by interrupting peptic 
digestion at an early stage, and experimenting upon the products then 
im solution. By interrupting peptic digestion at an early stage, two 
substances were obtained: one was a neutralisation precipitate, w hich, on 
tryptic digestion, afterwards yielded only antipeptone, and was hence 
named antialbwmose ; the other, obtained from the filtrate, was de- 
composed by trypsin, with formation of leucine and tryosine, and was 
hence named hemialbumose* Kiihne® also reinvestigated the action of 
acids, renaming Schiitzenberger’s hemiprotein antialbumid, and a body 


1 Briicke, Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1859, Bd. xxxvii. S. 182; Otto, 
Ztschr. f. physiol. Chem., Strassburg, 1883, Bd. viii. S. 129; Hasebroek, ibid., 1887, Bd. 
xi. S. 348; A. Herrmann, ibid., 1887, Bd. xi. S. 508; Neumeister, Ztschr. f. Biol., 
Miinchen, 1890, Bd. xxvii. 8. 310. 

2 Arch. de physiol. norm. et path., Paris, 1893, tome xxv. p. 447. 

3 Verhandl. d. naturh.-med. Ver. zw Heidelberg, 1877, Ne B., Bd.i..S. 23 

4 Vide infra. > Loc. e 


406 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


closely resembling Meissner’s parapeptone antialbumate; considering 
them anti bodies, from the fact that they do not yield leucine and 
tyrosine on tryptic digestion, but are, though with difficulty (especially 
in the case of antialbumid), converted into antipeptone. 

Kiihne gave the following graphic representations of the cleavage of 
proteids by acids and by digestion :— 


Scheme of Proteid Cleavage by Acids. 


ALBUMIN. 
——————$_—$————— 
Antigroup. Hemigroup. 
SSS 
Antialbumid. 
Antialbumate. - 
Antialbumose. Hemialbumose. 
Antipeptone. Hemipeptone. 


Scheme of Digestive Cleavage of Proteids. 
ALBUMIN 
(ALBUMINATE). 
| 
| 


| 
Antialbumose. Hemialbumose. | 
\ 


Peptic if 
Digestion. | Tryptic 
Antipeptone. Antipeptone. Hemipeptone, Hemipeptone. if Digestion. 


Leucine. Tyrosine. Leucine. Tyrosine. 


| 

Kiihne, in conjunction with Chittenden,! subsequently investigated 

more minutely the intermediate products in peptic digestion, and those 

formed by the action of dilute acids. The following is an account of 
the substances obtained and their mode of preparation :— 


Antialbumid.—This substance was prepared as follows :—The white of fifty 
eggs, freed from membrane and much diluted, was made feebly acid with 
sulphuric acid and coagulated by boiling. The coagulum was suspended in 
1300 c.c. of water containing 7 c.c. of sulphuric acid and heated to 100° C. ; after 
ten hours it appeared little altered and was filtered off. The filtrate gave on 
neutralisation a precipitate principally composed of acid albumin. After 
removal of the first acid, the albumin which had remained undissolved was 
heated with 3 litres of } per cent. sulphuric acid to 100° C. for nineteen hours, 
then collected on a filter and completely washed. 

The albumid thus obtained was insoluble both in dilute and concentrated 
acetic acid, and in hydrochloric acid of 1:4 per mille and stronger, but easily 
soluble in dilute caustic soda solution and in dilute alkaline carbonates, from 
which it was precipitated by concentrated sodium chloride. Purified by diges- 
tion with gastric extract and 4 per mille hydrochloric acid for six hours at 
40° C., it remained undissolved, but changed in appearance, becoming clotlike. 
The clot was washed with water, dissolved in 1 per cent. solution of sodium 
carbonate, filtered, reprecipitated with sulphuric acid, and washed again. It 
now dissolved in 2 per mille hydrochloric acid, and in this solution was digested 
with good peptic extract for eighteen hours. It was unchanged, and reappeared, 
in equal amount to the eye, on neutralisation of the solution. 


1 Ztschr. f. Biol., Miinchen, 1883, Bd. xix. S. 159. 


CLEAVAGE THEORY OF PROTEID DIGESTION. 407 


Now washed with water until no reaction for chlorides was obtained, and 
afterwards treated with alcohol and ether, it formed a powder of slightly 
yellowish colour. A part of this purified antialbumid was dissolved in sodium 
carbonate solution of 5 per cent., and treated with a dialysed and very active 
trypsin solution at 37°-38°C. After thirty minutes the mixture began to be 
turbid, and in two hours solidified to a clot. By breaking up the clot and 
filtering, the fluid part was separated from the clot; it was made scarcely 
turbid by neutralisation, and yielded by further digestion no new precipitate, but 
contained a fair amount of peptone. 

The separated clot was soluble in hydrochloric acid of 2 per mille, but as 
insoluble in sulphuric acid of 4 per mille as the original precipitate. It was 
completely precipitated from solution in 1 per cent. sodium carbonate solution 
by concentrated sodium chloride solution. From this it seems that in the 
coagulation of albumid in trypsin no change takes place other that its becom- 
ing more insoluble in sodium carbonate solution. The action of trypsin in 
more alkaline solution was next tried; after the first precipitation of the 
albumid it was dissolved in °75 per cent. sodium carbonate solution, digested 
with dialysed tryptic fluid, neutralised and filtered. The clotlike albumid was 
dissolved in 5 per cent. sodium carbonate solution, and by repeated digestion 
with dialysed tryptic fluid, the greater portion was converted into antipeptone. 
The final residue from this much accentuated tryptic digestion was completely 
insoluble even in 5 per cent. sodium carbonate solution, but dissolved in 1 per 
cent. caustic soda. Precipitated by neutralising with hydrochloric acid, 
washed, redissolved in sodium carbonate, and treated with trypsin anew, it was 
again completely thrown out as a clotlike coagulation. No leucine or tyrosine 
was present in the tryptic filtrates. 


How widely this account differs from the statement which occurs in 
most text-books, that antialbumid is not attacked by pepsin, but is 
converted into antipeptone by trypsin, may easily be seen. In a fluid of 
equal alkalinity to that found in the body, antialbumid is no more 
digested by trypsin than it is by pepsin and hydrochloric acid. Now 
it has been shown that trypsin is most active in a sodium carbonate 
solution of about 1 per cent.) and considerably less active in one of 5 
per cent.; why then does trypsin in 5 per cent. solution do that which it 
is unable to do in 1 per cent. solution? Obviously because the 5 per 
cent. solution dissolves the clot of antialbumid, while the 1 per cent. 
solution does not. In the former case a weaker trypsin acts on anti- 
albumid in solution; in the latter, a stronger trypsin on antialbumid as 
an insoluble precipitate. 

Be this as it may, antialbumid is only with great difficulty and 
incompletely peptonised by trypsin. In all its properties, from its mode 
of formation onward, the substance appears to be merely a very insoluble 
form of acid albumin. 

Antialbumose—By a fractionated peptic digestion, Kiihne and 
Chittenden? obtained a substance which they termed antialbumose. 
The preparation of this substance from white of egg is as follows :— 


The white of fifty eggs was freed from membrane, diluted and coagulated 
by boiling after acidifying with acetic acid. The coagulated proteid was 
digested in two litres of 4 per mille hydrochloric acid and one litre of dialysed 
gastric extract for one and a half hours at 40°C., it was then allowed to cool 
to the temperature of the room and filtered from the undissolved part, the 
process of filtration oceupying two days. The undissolved residue was again 
treated with fresh gastric extract until it was all dissolved, which occupied 


1See p. 338. aries cite, p. Lil. 


408 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


fifteen hours. After filtration the fluid was neutralised, and the neutralisation 
precipitate separated. This precipitate was digested anew for forty-eight 
hours with 150 c.c. of strong gastric extract, after which it was re-obtained on 
neutralisation not sensibly diminished in amount. Dissolved in °75 per cent. 
sodium carbonate, and mixed with powerful dialysed pancreatic extract, it gave 
no clot (see “ Antialbumid”) when kept for forty-eight hours at 40° C., and 
neutralisation precipitated only a part, the rest being converted into peptone. 
This last neutralisation precipitate showed the properties of antialbumid ; 
dissolved in sodium carbonate solution of 1°8 per cent., it was clear at first, but 
began to cloud in one to two hours, and in twenty-four hours about half had 
set into a thick clot which could not be peptonised completely by either peptic 
or tryptic digestion. The various pancreatic solutions separated from the 
neutralisation precipitates contained only peptone, and were free from leucine 
and tyrosine. The antipeptone here obtained contained 30 per cent. of ash. 


Of these three anti-compounds it is only claimed that one, anti- 
albumose, is a product of natural digestion; the other two, antialbumid 
and antialbwmate, are admittedly products of acid action or of acid and 
very weak peptic solution, which amounts to the same thing,—and the 
fact that they cannot be converted into peptones by the prolonged and 
repeated action of pepsin and hydrochloric acid proves that they are not 
natural products of strong peptic digestion in which no such inconvertible 
residue is formed. Antialbumose is commonly stated to be convertible 
by prolonged peptic digestion into peptone; but, as may be seen from 
the above description, it is not materi ially altered by forty- eight hours’ 
digestion with a strong extract of gastric mucous membrane, “and even 
with trypsin a considerable portion is left unaltered, betraying all the 
properties of antialbumid. Antialbumose possesses all the chemical 
properties of an acid albumin and none of those of the albumose class, so 
that its name is a misnomer; no such substance as an antialbumose has 
actually been isolated. Antialbumid, antialbumate, and antialbumose, 
to place them in the order of their solubility and facility for under- 
going decomposition, are three substances all of which are remarkably 
resistant to both peptic and tryptic digestion, and belong more to the class 
of acid albumins than to any other. It is now generally recognised that 
acid albumin is a generic and not a specific term, and it is to be hoped 
that room will soon be found for these three bodies in this class, and the 
terminology of digestion left a little less complicated than it is at present. 

It may ‘be asked, W hy was antialbumose, if it is not a natural product 
of peptic digestion, obtained in the above experiment ? The authors 
themselves remark on the close resemblance between their product 
and Meissner’s parapeptone. The latter is produced either by the action 
of dilute acid or of a very weak pepsin solution in the presence of acid. 
Now for two days, while filtering at atmospheric temperature, after the 
first hour and a half of digestion, the substance was under exactly the 
proper conditions for the pr oduction of parapeptone. Finally, no product 
so resistant to both pepsin and trypsin, as this substance is shown to be 
by the above description, is formed during uninterrupted digestion. 


Another method for preparing “ antialbumose.” —Kiihne and Chittenden! 
also prepared antialbumose from fibrin by a somewhat similar course of 
procedure, except that there was here no two days’ delay in filtering, since the 
fibrin was more quickly dissolved. There is, however, an objection no less 
fatal, as will be pointed out after a description of the process. 


1 Loc. cit. 


CLEAVAGE THEORY OF PROTEID DIGESTION. 409 


Five hundred grms. of unboiled fibrin, squeezed as dry as possible with the 
hand, were placed at room temperature for twenty-four hours in 5 litres of 0°2 
per cent. hydrochloric acid; the mixture was then heated to 37° C., and 
100 c.c. of gastric extract added. Solution took place inside an hour, after 
which the fluid was filtered through a hair sieve, digestion stopped by neutral- 
isation, and th» neutralisation precipitate filtered off. This precipitate is stated 
to be essentially antialbumose. It was long washed with water, and did not 
then dissolve easily in 0°2 per cent. hydrochloric acid, so was heated for some 
hours at 40°C. This acid solution was treated with an equal volume of strong 
gastric extract in 0-2 per cent. hydrochloric acid for forty-eight hours, again a 
heavy neutralisation precipitate was obtained. This precipitate, after washing 
with water thoroughly till no biuret peptone reaction was given, was treated 
with sodium carbonate solution of 2°5 per cent., in which it was not easily soluble, 
and the solution was not clear until it had been digested for forty-eight hours at 
48°C. with trypsin. Even then, on neutralising, a precipitate behaving like 
antialbumid was obtained. Redissolved in 2°5 per cent. sodium carbonate solu- 
tion, and redigested with trypsin, it was again precipitated in clotlike flakes, 
and was only very slowly and partially converted by repeated tryptic digestion. 


Here, again, there is no guarantee, after heating the first neutralisation 
precipitate for some hours with 0:2 per cent. hydrochloric acid in order 
to dissolve it, that a natural digestion product remains to be dealt with 
in the subsequent processes. In addition, the obstinate resistance of the 
substance to both peptic and tryptic digestion proclaims it a product of 
experimental procedure, and not a true stage in natural or uninterrupted 
digestion. 


Hemialbumose.—Kiihne and Chittenden! also obtained a precipitate, to 
which they gave the name of hemialbumose ; this was obtained from the pro- 
ducts of fractional peptic digestion in the filtrate after the removal of the 
so-called antialbumose by neutralisation. This filtrate was concentrated to one- 
fourth of its volume, acidified with acetic acid, boiled and filtered from a scanty 
coagulum, again concentrated and precipitated by the addition of excess of 
alcohol. In this precipitate by alcohol, the authors recognised, besides peptones, 
two forms of albumose, soluble and insoluble hemialbumose. The precipitate 
was rubbed up with cold water, until the wash water no longer gave the biuret 
reaction. A part of the albumose (soluble hemialbumose) went into solution, 
accompanied by all the peptone, a part remained insoluble (insoluble hem1- 
albumose). The latter substance was not pure, but contained a proteid substance 
insoluble in 2 per cent. acetic acid and in sulphuric acid of 0-4 per cent., and 
with difficulty soluble in dilute caustic soda solution. The “insoluble hemialbu- 
mose” was separated from this by treating with boiling water. From solution 
in boiling water a part of the “insoluble hemialbumose ” was precipitated as 
the solution cooled. This was separated ; the remainder was precipitated from 
the cold solution and added to it. The “soluble hemialbumose ” was obtained, 
free from its admixture with peptone in the cold water extract, by Salkowski’s 
method of boiling with excess of sodium chloride and dilute acetic acid so as 
to form a saturated solution, washing the precipitate with saturated sodium 
chloride solution, dissolving in water and dialysing until the dialysate gave 
no reaction for chlorides with silver nitrate. 


These hemialbumoses on tryptic digestion yielded leucine and tyrosine 
abundantly, but could not be completely broken up by such digestion, 
a variable amount of peptone being always left, no matter how prolonged 
the digestion, which could only (on the cleavage theory) be antipeptone, 
and so pointed to impurities in the form of anti-compounds in these 


1 Loc. cit. 


410 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


hemialbumoses (or otherwise to the non-existence of cleavage at the 
albumose stage into hemi and anti groups). Nor, when these hemi- 
albumoses were subjected to more prolonged digestion yielding hemi- 
peptone (?), could this substance be completely broken up by prolonged 
tryptic digestion. 


Kiihne! also described as hemialbumose a substance occasionally found in 
the urine of patients suffering from osteomalacia, and first discovered by 
Bence Jones. Much has been made of the importance of this albumose by 
the supporters of the cleavage theory, but there is no more evidence that it is 
a pure hemialbumose than there is in the case of the substances described 
above ; that is to say, it has not been shown to be completely broken up by 
tryptic digestion, and this is the crux of the whole question. The fact that it 
yields leucine and tyrosine proves nothing. It has not been experimentally 
shown that no peptone is left after the prolonged action of trypsin upon it. 


Separation of the various albumoses from the “hemialbumose” pre- 
cipitate—Stimulated by a desire to obtaim a pure hemialbumose which 
should be capable of complete decomposition past the peptone stage by 
trypsin, and encouraged in the belief that hemialbumose was a mixture, 
as well by the known existence of two physically different forms (the 
soluble and insoluble described above) as by certain inconstancies in its 
behaviour towards sodium chloride, Kiihne and Chittenden? set to work 
again upon the subject, and although they did not quite achieve their 
object, produced a research which, whether the cleavage theory stands 
or falls, must, from the experimental point of view, always remain of the 
highest value, containing as it does the first basis for a classification of 
the albumoses, the first light cast upon the relationship of this class 
of proteids. 

From the hemialbumose described in their previous paper, they were 
able to separate, by the action of sodium chloride under various 
conditions, four substances with the following properties :— 

1. Protoalbumose—Precipitated by saturation with sodium chloride, 
soluble in cold and hot water. 

2. Heteroalbumose.—Also precipitated by saturation with sodium 
chloride, but insoluble in cold and in boiling water; soluble in dilute and 
in moderately concentrated saline solution. 

3. Dysalbumose-—The same as heteroalbumose, but insoluble in 
saline solution. This solution was recognised to be merely a more 
insoluble modification of heteroalbumose; each of the two substances is 
easily convertible into the other. Dysalbumose corresponds to the 
“insoluble albumose ” of the earlier paper. 

4. Deuteroalbumose is not precipitated by saturation with sodium 
chloride alone, but is precipitated by saturation with sodium chloride in 
the presence of acetic acid, and is soluble in water. 

These various albumoses were subjected to tryptic digestion, and it 
was found that none was a pure hemialbumose,—all yielded more or less 
unconvertible peptone accompanied by leucine and tyrosine. A bigger 
yield of amido-acids was obtained from protoalbumose and deutero- 
albumose than from heteroalbumose ; indeed, the latter showed itself to 
be more an anti- than a hemi- body, while protoalbumose yielded very 
little peptone and an abundance of amido-acids. After this evidence 


1 Ztschr. f. Biol., Miinchen, 1883, Bd. xix. S. 209. 
Sides. Bd. xx SH ele 


CLEAVAGE THEORY OF PROTEID DIGESTION. 411 


the term hemialbumosé, as applied to the substance, or rather mixture 
of substances, described above, ought to have speedily disappeared ; 
unfortunately it has not yet done so. 

Soon after this a valuable aid to the study of the albumoses was 
found in the discovery of Wenz, that saturation with ammonium 
sulphate precipitated all albumoses from solution, while the peptones 
remained dissolved. Heynsius? first noticed the powerful action of 
ammonium sulphate as a proteid precipitant, but fell into error in 
thinking that it precipitated peptones as well. More careful experiments 
by Wenz, in Kiihne’s laboratory, showed that it did not precipitate 
peptones, and so it was instituted as a means of separating albumoses 
and peptones. The statement, however, that saturation with ammonium 
sulphate totally precipitates albumoses and leaves peptones dissolved, 
can only be made with a certain reservation. Certain proteid sub- 
stances remain unprecipitated by saturation with ammonium sulphate, 
and these may conventionally be labelled peptones; but it has been 
shown® that, in order to precipitate completely bodies which had 
been known as albumoses before the introduction of ammonium sul- 
phate, it is necessary to help the ammonium sulphate by saturating in 
dilute solution and with varying reaction. If these bodies had not 
been classed with the albumoses before Wenz’s discovery, they would 
probably now be peptones; so conventional and artificial as this is the 
proteid classification with which at present we are forced to be content. 
In little or nothing except unimportant physical differences are the 
albumoses and peptones distinct. If ammonium sulphate did not exist, it 
would be difficult to say how to draw a sharp line between them: * both 
classes of bodies give the same reaction to the biuret test, and both are 
diffusible, though the albumoses more slowly so than the peptones.’ 

Separation of albumoses and peptones—The following is the method 
recommended by Kiihne ® for separating albumoses from peptones :— 


The fluid containing the products of digestion is freed from albuminates 
and coagulable proteids in the usual manner, and then, when sujjiciently diluted 
and of nearly neutral reaction, is saturated while boiling with ammonium 
sulphate, and separated on cooling from the excess of salt and precipitated 
albumose. The solution is again heated, and after it commences to boil it is 
made strongly alkaline by the addition of ammonia and ammonium carbonate, 
then again saturated with ammonium sulphate, and once more allowed to cool, 
when a second precipitation of albumose and excess of salt takes place. A 
third time heated, until the smell of ammonia disappears, it is once more 
saturated while warm and made decidedly acid in reaction by the addition of 
acetic acid, when, on cooling, a third and last precipitation of albumose takes 
place, and the filtered fluid is supposed to contain nothing proteid except 
peptone ; amphopeptone if the original fluid was the result of gastric digestion. 
The albumoses can be obtained by dialysis and concentration from the united 
precipitates. 


1Ztschr. f. Biol., Miinchen, 1886, Bd. xxii. S. 1. 

2 Arch. f. d. ges. Physiol., Bonn, 1884, Bd. xxxiv. S. 330. 

’Kiihne, Zschr. f. Biol., Miinchen, 1893, Bd. xxix. 

4For a discussion of this point see Pekelharing, Arch. f. d. ges. Physiol., Bonn, 1880, 
Bd. xxii. S. 185; 1881, Bd. xxvi. 8S. 515; Internat. Beitr. z. wissensch. Med. Festschr. R. 
Virchow . .., Berlin; Ztschr. f. Biol., Miinchen, 1891, Bd. xxviii. S. 567; Neumeister, 
ibid., S. 361; Kiihne, zbid., S. 571. 

>See Kiihne, Ztschr. f. Biol., Miinchen, 1892, Bd. xxix. S. 20; Chittenden and 
Amerman, Journ. Physiol., Cambridge and London, 1893, vol. xiv. p. 483. 

Loe. cit. 


412 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


The amphopeptone is obtained from the filtrate after removal of the 
ammonium sulphate by complicated methods, consisting essentially in the 
removal of ammonium sulphate as far as possible by concentration ; solution 
of the amphopeptone in weak alcohol; removal of as much ammonium 
sulphate from the weak alcohol as possible by a freezing mixture ; removal of 
the alcohol by distillation ; removal of the last portions of ammonium sulphate 
by boiling with barium carbonate ; removal of the last traces of barium salts by 
cautious addition of dilute sulphuric acid; and finally, precipitation of the 
amphopeptone by excess of absolute alcohol. 


Neumeister’s method for separating the albumoses of peptic digestion. 
—The method of Kiihne and Chittenden for the separation of the 
various albumoses has been perfected by Neumeister,! who has in 
addition proved that these bodies are not formed synchronously in the 
process of digestion, or other form of hydrolysis, but that there are two 
stages in the process. In the first stage proto- and heteroalbumoses are 
formed, which are called for this reason primary albumoses ; in the second 
stage each of these primary albumoses gives rise to a deuteroalbumose, 
and these deuteroalbumoses are hence called secondary albumoses. 

Since heteroalbumose is completely and protoalbumose only partially 
precipitated by saturation with sodium chloride in neutral solution, 
while deuteroalbumose is not precipitated at all, it is easy, from a 
mixture of all three albumoses, to obtain a solution containing only 
heteroalbumose and protoalbumose ; and on dialysis of this solution 
heteroalbumose, being insoluble in water, is precipitated alone, leaving 
in solution only pure protoalbumose. In this way pure proto- and 
heteroalbumoses can be obtained, but the preparation of pure deutero- 
albumose is not quite so easy. In the filtrate from saturation with 
sodium chloride there is not only deuteroalbumose but the unprecipitated 
residue of the protoalbumose, and on adding acetic acid this is thrown 
out along with the deuteroalbumose. However, a loophole is left in the 
fact that just as saturation in neutral solution does not precipitate all 
the protoalbumose, so saturation in acid solution does not precipitate all 
the deuteroalbumose. Neumeister took advantage of this, sacrificed 
the first portion of deuteroalbumose thrown out by the acetic acid, 
accompanied by the last portions of protoalbumose, and then precipitated 
the fraction of deuteroalbumose left alone in solution by saturation with 
ammonium sulphate. 


Kiihne and Chittenden had already got round this difficulty of isolating 
deuteroalbumose by treating a dried mixture of the albumoses, such as is found 
in Witte’s peptone, with neutral and saturated solution of sodium chloride. 
Here the deuteroalbumose only passes into solution. Although the proto- 
. albumose would only be partially thrown out of solution by saturating with 
sodium chloride, yet it has not the power when dry to pass into solution 
in such a solvent. Witte’s peptone is, however, a variable mixture, and 
Neumeister, working with other samples, was unable to reobtain Kiihne and 
Chittenden’s result; it may be that they were working with a sample 
containing little or no protoalbumose. 


Neumeister effects the separation as follows :— 


The faintly acid solution is saturated with ammonium sulphate, and so 
separated from peptones. The precipitate is dissolved by the addition of 
water, separated from the excess of the salt by dialysis, and then the neutral 


1 Zischr. 7. Biol., Miinchen, 1887, Bd. xxiii. S. 381; ibid., 1888, Bd. xxiv. S. 267 ; <bid., 
1890, Bd. xxvi. S. 324. 


CLEAVAGE THEORY OF PROTEID DIGESTION. 413 


solution is precipitated by saturation with sodium chloride, so throwing out 
all the heteroalbumose and part of the protoalbumose which are separated 
by dialysis. In the filtrate from saturation with sodium chloride in neutral 
solution are the remainder of the protoalbumose and the whole of the deutero- 
albumose ; to this, acetic acid solution, which has been saturated with sodium 
chloride, is added, till a small portion filtered through a dry filter paper no 
longer gives a precipitate with copper sulphate solution.1 The mixed pre- 
cipitate of proto- and deuteroalbumoses is now filtered off, and deuteroalbumose 
is isolated from the filtrate by neutralising, dialysing off the sodium chloride, 
and precipitating by saturating with ammonium sulphate, or by adding excess 
of alcohol. 


This method of separating the albumoses may be shown schematically 
thus :— 


MIXED ALBUMOSES 
(saturated with sodium chloride in neutral solution) give 


Heteroalbumose and Protoalbumose Protoalbumose and Deuteroalbumose 
(Precipitate). (Filtrate). 
On dialysis, the solution of these two On adding acetic acid in saturated sodium 
gives chloride, this solution gives 
| 
| 
Heteroalbumose Protoalbumose Protoalbumose and Deuteroalbumose 
(Precipitate). (Solution). Deuteroalbumose (dialysed and pre- 
(not further treated) cipitated by alcohol) 
(Precipitate). (Filtrate). 


Neumeister also tested the action of hydrolysing agents on pure proto- and 
heteroalbumoses prepared as has just been described. He showed that boiling 
for three-quarters of an hour with 5 per cent. sulphuric acid was sufficient 
to convert protoalbumose into deuteroalbumose accompanied by some peptone. 
This was shown by the absence of turbidity on dialysis after neutralising 
(absence of heteroalbumose), by saturation in neutral solution with sodium 
chloride causing no precipitate (absence of protoalbumose), and by precipitation 
occurring on making the saturated solution in sodium chloride acid with acetic 
acid (presence of deuteroalbumose). In a similar fashion the conversion of 
heteroalbumose into deuteroalbumose, by boiling with acid, was demonstrated ; 
here a considerable formation of antialbumid was observed during the process. 
On peptic digestion proto- and heteroalbumose each yielded a deuteroalbumose, 
but they behaved differently towards trypsin. In the case of heteroalbumose, 
a specific point could easily be determined, in the course of digestion with 
trypsin in 0-2 per cent. sodium carbonate solution, when, in the presence of a 
considerable quantity of peptone, only deuteroalbumose was present; on the 
other hand, deuteroalbumose could not be obtained in large quantity by the 
action of trypsin on protoalbumose ; the products obtained were chiefly amido- 
acids accompanied by a little peptone, this being probably due to the ease 
with which the deuteroalbumose formed from protoalbumose undergoes decom- 
position. 

Neumeister confirms the results obtained by Kiihne and Chittenden, that 
heteroalbumose is principally an antialbumose, but has some hemialbumose 
mixed with it, while the composition of protoalbumose is the exact reverse, 
it being essentially a hemialbumose, always accompanied, however, by some 
antialbumose. The yield of unalterable peptone was, however, so small in 
some experiments as to induce Neumeister to believe that perfectly pure proto- 
albumose would contain only hemi groups, or, in other words, be completely 
convertible by tryptic digestion into amido-acids. The deuteroalbumose 


' This isa much more delicate test for protoalbumose (given by 1 in 5000) than acetic 
acid and saturated sodium chloride solution (1 in 2000). 


414 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


formed from protoalbumose and that from heteroalbumose are distinct bodies, 
being distinguished by the fact that the deutero-compound formed from 
protoalbumose is to some extent soluble in saturated solution of ammonium 
sulphate.! 


Starting with fibrin, and forming albumoses from it both by the 
action of acids and by peptic digestion, Neumeister also showed that in 
order of time proto- and /eteroalbumoses first appeared, to be followed 
later in the process by deuteroalbumose. 

Fibrin was boiled for three-quarters of an hour with 1 per cent. 
sulphuric acid, after which the fluid was neutralised, and the neutralisa- 
tion precipitate removed. In the filtrate both proto- and heteroalbu- 
moses were found, but not a trace of deuteroalbumose; the latter first 
appeared after some hours’ boiling, and by a continuance of the process 
increased at the expense of the proto- and hetero-compounds so as to be 
present finally in preponderating quantity. 

In accordance with these experiments, Neumeister? considers that 
the peptic digestion of proteids takes place as represented in the follow- 
ing scheme, in which the preponderance of any group is shown by a 
dark line, while its presence in small quantity is signified by a light 
‘line :— 

Proteid Molecule, 
consisting of 


Hemigroups Antigroups 
Protoalbumose Heteroalbumose Antialbumid 
(Amphoalbumose) (Amphoalbumose) 
Deuteroalbumose Deuteroalbumose Deuteroalbumose 
(Amphoalbumose) (Amphoalbumose) (Antialbumose) 
Amphopeptone Amphopeptone Antipeptone 


TryPtTic DIGESTION OF PROTEIDS. 


The proteolytic action of the pancreatic juice has not been known 
for nearly so long a period as that of the gastric juice; it was first 
clearly proclaimed by Corvisart® in 1857, although this author refers to 
an earlier statement, by Purkinje and Pappenheim in 1836, that extracts 
of pancreas possess a dissolving action on proteids. 

Claude Bernard* knew that pancreatic juice in the presence of bile 
had the power of dissolving proteids, but stated that when alone it 
had no such action, unless the proteid matter had previously been sub- 
jected to the action of bile. This error was removed by Corvisart, who 
clearly proved that pancreatic juice alone at the temperature of the 


1 Ztschr. f. Biol., Miinchen, 1888, Bd. xxiv. 8. 267. 

2 Tbid., Miinchen, 1887, Bd. xxiii. S. 381. See also Neumeister, ‘‘ Lehrbuch der 
physiologischen Chemie,” Jena, where Neumeister concludes: — ‘‘The expression 
hemipeptone has, according to this representation, only a theoretical meaning, and the 
term hemialbumose corresponds to older notions and ought to be allowed gradually to 
disappear from the text-books.” 

3 «Collection de mémoires sur une fonction peu connue du pancréas, la digestion des 
aliments azotés,”’ Paris, 1857. 

4“ Tecons de physiologie expérimentale,” 1856, tome ii. p. 440. 


CLEAVAGE THEORY OF PROTEID DIGESTION. 415 


body has a powerful digestive action on proteids in fluids of either 
alkaline, acid or neutral reaction. In addition, he showed that infusions 
of the fresh gland possess a similar action, that the active material 
is precipitated by excess of alcohol and is dissolved again on the 
addition of water to the precipitate, and that the activity of extracts 
of the gland depends on the time after a meal at which the animal 
is killed, being most active when a gland is extracted that has been 
obtained from an animal killed six to nine hours after a full meal. 
Corvisart also showed that the proteids are not merely dissolved, but 
converted into substances possessing the same general characters as 
those formed in peptic digestion. 

These important results were denied at first by some observers, who 
failed for some reason to obtain them on repeating Corvisart’s experi- 
ments, but were in the end abundantly confirmed by the researches of 
Meissner} Danilewsky2 and Kiihne, and are now universally accepted. 

Kiihne not only confirmed the results of Corvisart, but made an 
important advance, by showing that pancreatic juice owes its action to 
an enzyme, to which he gave the name of trypsin. He next showed 
that, although trypsin is precipitated by excess of salicylic acid, smaller 
quantities of that substance do not stop the action of the enzyme, 
while they do, as shown by Kolbe, stop the growth of organisms, 
especially those concerned in putrefaction. Until this was ascertained, 
digestion experiments with pancreatic juice were complicated by the 
putrefactive changes by which digestion was accompanied, for, while 
trypsin acts in a neutral, and even in a faintly acid medium, its action 
is stopped and the ferment gradually destroyed in a medium sufficiently 
acid to stop the growth of bacteria by virtue of its acidity alone, so that 
no one had been able to carry out prolonged experiments on pancreatic 
digestion without the accompaniment of putrefaction. For this reason 
it was unknown whether certain substances which appear towards the 
end of the digestion were really due to the action of the enzyme or 
were products of the putrefaction. Kiihne was the first to carry out 
antiseptic digestion, and to show that these substances are really formed 
by the agency of the trypsin; he also perfected a method of freeing 
solutions of the enzyme from the products of proteid digestion, resulting 
either from the self-digestion of the gland in the preparation of the 
extracts or otherwise, thus clearing the way for a study of the various 
products formed by the action of trypsin on proteids. 

Instead of preparing a purified solution of trypsin, which is a 
rather troublesome process, the power possessed by fibrin of absorbing 
the ferment, as described in the case of peptic digestion, may be 
utilised here also; but if the digestion of coagulated proteids is to be 
observed, a purified solution of trypsin must be first prepared.® 

The first action of trypsin seems to be a simple solution of the 
proteid which is undergoing digestion. This effect is most easily observed 
if fibrin is the proteid ‘undergoing digestion, when the coagulable proteid 
present in the solution, just before the fibrin is completely dissolved, has 


1 Ztschr. f. rat. Med., 1859, Dritte Reihe, Bd. vii. S. 1. 

2 Virchows Archiv, 1862, Bd. xxv. S. 279. 

° Thid., 1867, Bd. xxxix. S. 130. 

4 Verhandl. d. naturh.-med. Ver. xu Heidelberg, 1877, N. F., Ba. i. S. 233. 

>See Neumeister, ‘‘ Lehrbuch der physiologischen Chemie,” Jena, 1893, S. 198; 
K. Mann, ‘‘ Ueber die Absorption der proteolytischen Enzyme durch die Eiweisskorper,” 
Diss., Wiirzburg, 1892, S. 23. 


416 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


the properties of a globulin, but in the case of serum albumin no such 
formation of a globulin takes place.t If the proteid employed has 
previously been coagulated, no formation of a coagulable proteid is 
observed, the first product being apparently deuteroalbumose.” 

The appearances presented by proteid undergoing solution by the 
action of pepsin and of trypsin respectively, are characteristically 
different. In the case of pepsin and hydrochloric acid, the proteid 
swells up, becomes transparent or translucent, and gradually dissolves ; 
while, by the action of trypsin in alkaline solutions, the proteid does not 
swell up or become clearer, but is attacked and eroded from the outside. 

After being dissolved, the proteid is further attacked by the trypsin 
and decomposed into various products, the final result being a certain 
amount of peptone which is not further acted on, accompanied by 
various nitrogenous bodies, of which those occurring im largest quantity 
are two amido-acids, leucine and tyrosine. 

The primary albumoses of peptic digestion are not found among the 
intermediate products of tryptic digestion. No matter at what stage 
digestion is interrupted, no trace of either proto- or heteroalbumose is 
found; the only albumose present is deuteroalbumose.* 


Neumeister suggests that this may be due to the protoalbumose being 
broken up as rapidly as it is formed into amido-acids, while the heteroalbumose 
is immediately converted into deuteroalbumose. Be this as it may, the 
experimental fact is, that neither protoalbumose nor heteroalbumose are 
found at any stage of tryptic digestion. 

According to Neumeister, the deuteroalbumose present is an anti-compound 
not yielding any amido-acids when subjected to the further action of trypsin.* 


Peptone is formed much more rapidly in tryptic than in peptic 
digestion, the preliminary stages being apparently rushed through ; while 
in peptic digestion scarcely any peptone is formed before complete 
conversion into albumoses has taken place, and complete peptonisation 
never occurs. 

The most essential difference between the digestive action of trypsin 
and that of pepsin lies in the discovery of Kiihne, that the action of 
the former enzyme does not cease with the formation of peptone, but 
that approximately one-half of the proteid, or of the peptone formed 
from it, is converted into a number of cystalline substances of much 
simpler composition. 

Not only does this take place in the direct tryptic digestion of proteids, 
but if peptone formed by peptic digestion be submitted to tryptic 
digestion, about one-half of it is decomposed in the above fashion. This 
experiment led Kiihne to the cleavage theory, and to naming, on the 
basis of this theory, the peptone of peptic digestion, amphopeptone; the 
peptone remaining after the completion of tryptic digestion, and which 
is no longer affected by renewed digestion, antipeptone; and that 
hypothetical substance which is supposed to form one moiety of the 
amphopeptone, and be broken up by the action of the trypsin, 


1 Neumeister, Zischr. f. Biol., Miinchen, 1887, Bd. xxiii. S. 398 ; ibid., 1890, Bd. xxvii. 
S. 311; Herrmann, Zschr. f. physiol. Chem., Strassburg, 1887, Bd. xi. S. 521. 

* When trypsin acts in an alkaline medium, alkali albumin is first formed ; but this is a 
very transient stage, the alkali albumin being quickly changed into deuteroalbumose. 

5 Otto, Ztschr. f. physiol. Chem., Strassburg, 1883, Bd. viii. S. 129; Neumeister, 
Ztschr. f. Biol., Miinchen, 1887, Bd. xxiii. S. 398. 

4 Zischr. f. Biol., Miinchen, 1887, Bd. xxiii. S. 381. 


CLEAVAGE THEORY OF PROTEID DIGESTION. 417 


hemipeptone. It will be seen from this that the term hemipeptone is 
a term for something which has a separate existence only in theory. 
There has as yet been no method either devised or fallen upon by 
accident of separating these two substances which are supposed by the 
cleavage theory to be present, mixed in equal proportions, in ampho- 
peptone. This is somewhat remarkable, in view of the number of years 
the theory has now been in vogue, and the large amount of experimental 
work that has been carried out in connection with it, and ought to be 
looked upon as an indication, either that amphopeptone is not really 
a mixture of antipeptone with a hypothetical hemipeptone, but a 
substance capable of breaking up under the action of trypsin into a new 
peptone (antipeptone) and a number of amido-compounds ; or that anti- 
and hemipeptones are not separately present in amphopeptone, but that 
this peptone breaks up upon the further action of trypsin into antipeptone 
and hemipeptone, and that this hypothetical hemipeptone is next acted 
upon and broken into simpler bodies, finally yielding leucine, tyrosine, 
and the other companions of antipeptone found in complete tryptic 
digestion. 

The decomposition of proteids by trypsin is represented by 
Neumeister! according to the following schema :— 


Proteid. 
Deuteroalbumose 


| 
Amphopeptone 
| 


| | 
Antipeptone Hemipeptone 
| 


| | | 
Leucine Tyrosine Aspartic Acid Tryptophan, ete. 


According to the same author, several deuteroalbumoses are formed, in the 
course of tryptic digestion, yielding corresponding amphopeptones. He also 
states that all the albumoses up to the present known, whether formed in 
peptic or tryptic digestion, are amphoalbumoses,—that is to say, yield both 
antipeptone and amido-acids on complete tryptic digestion. The ratio between 
the amounts of antipeptone and of amido-acids is a very variable one; 
heteroalbumose, for example, yielding much antipeptone and little amido-acid, 
while protoalbumose breaks up into much amido-acid and very little anti- 
peptone. Those who hold the cleavage theory explain this by saying that 
heteroalbumose is to a large extent an anti-substance, and protoalbumose 
almost purely a hemi-substance; but the experimental facts may be met 
equally well by the statement, that heteroalbumose is an albumose of such a 
chemical nature that it breaks up under the action of trypsin so as to yield a 
large percentage of peptone unalterable by further action of trypsin, accom- 
panied by a small amount of amido-acids; protoalbumose is an albumose 
different in nature from heteroalbumose, and yielding, on further tryptic 
digestion, very little peptone (antipeptone) and a large amount of the amido- 
acids. There is no more proof that either heteroalbumose or protoalbumose is 
such a mixture of albumoses as the cleavage theory demands, than there is 
that amphopeptone is such a mixture of the corresponding peptones. 


All the observed facts of peptic and tryptic digestion may be simply 
represented by the followimg schema, without any reference to the 
1 “Tehrbuch der physiologischen Chemie,” Jena, 1893, Th. 1, S. 200. 

VOL. I.—27 


418 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


cleavage or any other theory, save in the names of such of the substances 
as have been named on a theoretical basis :— 


Peptic DIGESTION. TryPptic DIGESTION. 
Proteid. Proteid. 
| | 
Acid Albumin Alkali Albumin 
| 
Deuteroalbumose 
Protoalbumose Heteroalbumose | 
j Antipeptone, amido-acids, ete. 
Deuteroalbumose 
Amphopeptone. 


In the above account of the intermediate products formed between 
proteid and peptone, an attempt has been made to poimt out how far 
each important experimental result is in agreement with, or lends support 
to, the cleavage theory of proteid digestion. Most of the results have 


been obtained by supporters of that theory, but these results fall far 


short of proving the truth of the theory, and may be explained without 
reference to anti- and hemi-bodies. The main points may here be 
summarised :— 


1. Certain substances have been obtained by the action of dilute acids on 
proteids, which do not yield amido-acids when subjected to prolonged tryptic 
digestion ; these substances have been on this account looked upon as pure 
anti-compounds. But there is no evidence that such substances are formed 
naturally in either peptic or tryptic digestion: there is evidence against it in 
the extreme difficulty with which they are attacked either by pepsin or 
trypsin. Neither are these substances in their chemical behaviour albumoses, 
so that the term antialbumose, as applied to any of them, is a misnomer. 

2. The substance originally obtained from a fractionated peptic digestion, 
and named hemialbumose, was afterwards shown by its discoverers to be a 
mixture of three bodies,—protoalbumose, heteroalbumose, and deuteroalbumose, 
and none of these three discrete bodies was found to be either a pure hemi- 
albumose or pure antialbumose, so that, if the cleavage theory is to be main- 
tained, we must be content to believe that each of these three is a mixture 
in varying proportions of anti- and hemi-groups, and admit the existence of 
antiprotoalbumose and hemiprotoalbumose, of antiheteroalbumose and hemi- 
heteroalbumose, of antideuteroalbumose and hemideuteroalbumose, without 
any experimental evidence whatever. Again, the cleavage theory takes no 
account of the fact that proto- and heteroalbumose are formed prior to the 
deuteroalbumose. 

3. Amphopeptone is supposed to be a mixture in about equal proportions 
of antipeptone and hemipeptone ; but these two bodies have never been isolated 
from it. Antipeptone can only be obtained from amphopeptone by the action 
of trypsin, and hemipeptone has never been obtained at all. 

4, There is no doubt that some forms of proteids, or altered proteids, are 
more easily decomposed by trypsin, yielding amido-acids, than are others ; but 
this does not prove that such bodies are variable mixtures of a fraction which 
is not decomposable at all with one which is completely decomposable. When 
from an ampho-body there have been isolated two fractions, one a pure anti- 
body that is completely unalterable by trypsin, the other a pure hemi-body 
that is completely decomposable into amido-acids by trypsin, then it will be 
time to believe in ampho-, anti-, and hemi-bodies. At present neither from 
amphopeptone, protoalbumose, heteroalbumose, or deuteroalbumose has there 


itll 


CLEAVAGE THEORY OF PROTEID DIGESTION. 419 


been such a separation, even partially, achieved, although these are admitted 
to be ampho-bodies by the supporters of the theory. 


But if the cleavage theory be not accepted, what explanation is there 
for the fact that different albumoses yield varying accounts of amido- 
acids, which suffer varying amounts of decomposition, under the action 
of trypsin ? 

The different proteids, and the products derived from them, differ so 
little in chemical composition (and this is especially true for the various 
albumoses), that the difference in their nature is probably due to a differ- 
ence in atomic grouping. Is it not probable, then, that some of these 
groups are much more susceptible of decomposition than others; that 
those albumoses which yield. much amido-acid contain more groups in 
their molecules which are decomposable by trypsin; that those which 
yield much antipeptone contain less of these decomposable groups; and 
that in all cases that substance (or substances) which we call antipeptone 
is the remainder after all those groups which are attackable by trypsin 
have been removed in the form of amido-acids ? 

It will be seen that this substitutes, for two molecules, one easily 
attackable, the other wholly unattackable by trypsin, one molecule; of 
which a portion, variable in the case of each albumose, is attacked by the 
trypsin and a residue left, in which there are no groups that the trypsin 
is able to attack; such a substitution relieves one from belief in a large 
number of substances of which the existence has never been proven. 

Again, if a cleavage of the proteid molecule takes place, at the begin- 
ning of the digestive process, into anti- and hemi-groups, of which the 
anti-groups, after passing through the albumose stage, become finally 
converted into antipeptone, while the hemi-groups, after passing through 
both albumose and peptone stage, become finally converted into amido- 
acids, one would expect, in an interrupted tryptic digestion, to find 
these intermediate hemi-products mixed with the intermediate anti- 
products; to find substances, corresponding to those found in peptic 
digestion, which would become on more complete tryptic digestion 
partially, at least, broken up into amido-acids. No such compounds or 
mixtures are, however, actually found; no hemi-compound is ever found 
at any stage of tryptic digestion. As already stated, proto- and hetero- 
albumose are never formed, only deuteroalbumose. 

Neither is there any evidence of the formation of such a substance 
as amphopeptone in tryptic digestion, only antipeptone is formed. In 
short, there is no evidence whatever in tryptic digestion of two parallel 
series of anti- and hemi-bodies proceeding pari passu into anti- and hemi- 
peptones, of which the latter becomes decomposed into amido-acids. If 
any hemi-bodies are formed, they are at once broken down into amido- 
acids, without passing through the preliminary stages of hemialbumose 
and hemipeptone ; at any rate, there is no experimental evidence of such 
a passage. Also, when protoalbumose is obtained as a product of 
fractional peptic digestion, and submitted to the action of trypsin, it is 
directly broken up into amido-acids, no deuteroalbumose or hemipeptone 
being discoverable as intermediate products. Similarly, heteroalbumose 
is in part converted into amido-acids, and in part into anti-deuteroalbu- 
mose, which passes later into antipeptone without any formation of 
hemi-deuteroalbumose or amphopeptone.t 

1 Neumeister, Ztschr. f. Biol., Miinchen, 1887, Bd. xxiii. S. 381, 


420 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


This is all easily accounted for on the supposition that a variable 
fraction of the proteid molecule is easily attacked and broken off into 
amido-acids by trypsin, but it is very difficult to explain on the sup- 
position that the proteid molecule, early in the process of decomposition, 
breaks up into two halves, of which one changes through the stages of 
hemialbumose and hemipeptone into amido-acids, while the other, 
passing through antialbumose, halts at antipeptone. 

Description of the products formed in the pancreatic digestion 
of proteids.—The products of tryptic digestion may be isolated most 
easily by experimenting with fibrin, either by impregnating it with the 
ferment, washing, and allowing it to digest in dilute sodium carbonate 
solution, or by digesting with a purified pancreatic extract. The pro- 
ducts present at different stages may be studied by removing at intervals 
a portion of the digest, stopping the digestive process, by boiling and 
then investigating the nature of the dissolved substances. 


Coagulable proteid.—Tf the test portion be removed before complete solution, 
or just on complete solution of the fibrin, it will be found to contain coagulable 
proteid ; on neutralising, part of this, being a globulin in character, is thrown 
out of solution, and the remainder on making faintly acid and boiling.! 

The deuteroalbumose of pancreatic digestion.—If, after removal of the 
coagulated proteid by filtration, the solution be now concentrated, deuteroalbu- 
mose can be precipitated from it by sodium chloride and acetic acid, and shown, 
by subjection to further action of trypsin, to be purely an anti-compound, or, 
in other words, to contain nothing in its molecule decomposable by the action 
of trypsin into amido-acids. This anti-deuteroalbumose, as already stated, is 
the only albumose found in tryptic digestion, and it is only found in the earlier 
stages. Another portion of the digest may be acidified, and the albumose 
thrown out of solution by saturation with ammonium sulphate, after which the 
presence of peptone in the filtrate may be shown, after dilution or dialysis, by 
the usual tests. 

After some days of tryptic digestion, the digest contains no coagulable 
proteid or albumose, but only antipeptone, and the simpler products formed 
by more complete demolition of part of the proteid molecule (or of the hypo- 
thetical hemi-moiety), such as the amido-acids. 

The peptone of tryptic digestion or antipeptone.—The peptone or peptones 
formed by the action of trypsin on proteids can best be obtained from a 
pancreatic digest which has been allowed to proceed to completion by 
repeated digestion during several days with trypsin and dilute sodium carbo- 
nate solution. This solution is concentrated to a small volume and filtered 
from the tyrosine, which separates out on cooling. The filtrate is saturated 
with ammonium sulphate, with the precautions described under peptic diges- 
tion,” and the ammonium sulphate is similarly removed. The antipeptone may 
now be precipitated by the addition of phosphomolybdic acid, the precipitate 
decomposed by baryta water, and excess of barium removed by cautious 
addition of dilute sulphuric acid. Finally, the solution is concentrated to a 
syrup on a water bath, and dried im vacuo over sulphuric acid.* 

Antipeptone agrees very closely in composition and properties with a 
monobasic organic acid (Fleischsiure) recently isolated by Siegfried + from 
muscle extract, of the composition and molecular weight represented by the 

1 See pp. 405, 415. 2 See p. 411. 

3 Kiihne, Ztschr. f. Biol., Miinchen, 1893, Bd. xxx. S. 1. 

4 Ber. d. k. stichs. Gesellsch. d. Wissensch., Math.-phys. Cl., 1893, 8. 485; Arch. f. 
Anat. u. Physiol., Leipzig, 1894, 8. 401; Ztschr. f. physiol. Chem., Strassburg, 1896, Bd. 
xxi. S. 360. See also C. W. Rockwood, Arch. f. Anat. u. Physiol., Leipzig, 1895, 8. 1; 
Balke u. H, 8, Ide, Ztschr. f. physiol. Chem., Strassburg, 1896, Bd. xxi. S. 380. 


AMIDO-ACIDS FORMED IN TRYPTIC DIGESTION. 42% 


formula C,,H,,N.0,. This substance gives a similar biuret reaction to that 
given by antipeptone; like it also, it does not give Millon’s reaction, is very 
hygroscopic, and, on decomposition with hydrochloric acid, forms lysine and 
lysatinine, but not tyrosine. It has also been obtained directly from the pro- 
ducts of advanced tryptic digestion ; it has been found in milk, and in traces 
in the urine. It is easily soluble in water; sparingly in cold, more so in hot 
alcohol, from which it crystallises in microscopic crystals. It is also soluble in 
carbolic acid and glacial acetic acid, but is decomposed by these solvents, 
especially at a high temperature. It combines with hydrochloric acid and with 
phosphoric acid (Phosphorfleischsiiure). The compound with phosphoric acid 
is the form in which it naturally occurs in the organism. Sjéqvist! has 
recently estimated the molecular weight of antipeptone by cryoscopic determina- 
tion at 250; this agrees very closely with the molecular weight similarly 
determined by Siegfried for his new acid, and increases the probability that 
the two substances are identical. 

When a proteid is subjected to tryptic digestion, a portion is decomposed 
beyond the stage of albumose or peptone, and there are formed several nitro- 
genous bodies of much simpler constitution; of these, some are amido-acids 
and some organic bases. Of these substances, two amido-acids, leucine or amido- 
caproic acid, and tyrosine or para-oxyphenylamido-propionic acid, are present in 
much larger quantity than the others, which only occur in traces. These others 
are aspartic acid or amido-succinic acid, glutamic acid or amido-pyrotartaric 
acid, butalanine or amido-valerianic acid; and of bases, ammonia, lysine, and 
lysatinine. Besides these substances of known composition, there is another 
substance of unknown composition formed, to which the name of tryptophan 
has been given, although it has never been isolated, and is only known through 
certain peculiar colour reactions which it gives. 

The amido-acids formed in tryptic digestion. Leucine.— Leucine 
is an amidocaproic acid ((CH,),CH.CH,.CH(NH,).COOH), and is always formed 
in any profound decomposition of proteid, such as boiling with dilute acids or 
alkalies, fusing with alkalies, in tryptie digestion, or in putrefaction. It has 
been found in nearly all the tissues in the body, and there has been much 
discussion as to whether it is a normal constituent here, or is formed as a 
post-mortem product. Certainly it is rapidly increased in amount, because of 
proteid decomposition, after death, but the evidence is strong for its normal 
presence in more or less pronounced traces in most of the organs in the fresh 
condition. It is, besides, a very common constituent of tissue in many 
pathological conditions, and also occurs in the vegetable world. 

Virchow showed that both leucine and tyrosine are found normally in the 
pancreas after death, and Kiihne afterwards showed that its amount here was 
much increased by auto-digestion of the gland tissue post-mortem. 

Leucine was first discovered by Proust in 1818 in putrefying cheese, and 
named by him cheese oxide (Kiise-oxyd). It was also obtained by Braconnet 
by decomposing animal matter with sulphuric acid.? 

Leucine may be prepared in many ways: by tryptic digestion of proteids, 
by boiling various forms of proteid with dilute acids or alkalies, with stannous 
chloride and hydrochloric acid, with bromine water in sealed tubes, or by 
fusing with caustic alkalies. A common method is that of boiling horn 
shavings with dilute sulphuric acid for many hours; but any form of proteid 
will yield it when so treated, such as meat, cheese, fibrin, wool, feathers, 
elastic tissue. 

Leucine has been obtained artificially by Limpricht,* by acting on isoval- 


1 Skandin. Arch. f. Physiol., Leipzig, 1896, Bd. v. S. 277. 

2 For a very full account of these bodies, see Gamgee, ‘‘ Physiological Chemistry of the 
Animal Body,” vol. ii. p. 231. 

3 Maly, Hermann’s ‘‘ Handbuch,” Bd. v. (2), S. 207. 

4 Ann. de chim., Paris, 1854, tome xciv. p. 243. 


422 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


eraldehyde with hydrocyanic and hydrochloric acids. Isovaleraldehyde 
(C,H,COH) is prepared, according to the general method, by oxidising amyl 
alcohol with potassium bichromate and sulphuric acid ; purified by forming the 
sodium bisulphite compound, decomposing this and collecting the distillate ; 
this is shaken with ammonia, when isovaleraldehyde-ammonia is thrown down 
in crystalline form. These crystals are washed with water, and then boiled 
with a mixture of strong hydrocyanic and dilute hydrochloric acids, when 
a reaction takes place yielding a body of the composition C,,H,,N,, which 
breaks up into leucine and ammonia. 


C,,H,,N, + 6H,0 =3(C,H,,NO,)+2 NH. 
(leucine) 
Leucine has also been obtained artificially by Hiifner,! by heating mono- 
bromocaproic acid with saturated ammonia under pressure to 120°-130° C. 
during four or five hours. 


C,H,,BrCOOH + NH, = C,H,,(NH,)COOH + HBr. 


Constitution of leucine.—That leucine is an amidocaproic acid is shown 
both by these methods of artificial preparation and by the following 
reactions :— 

1. Heated under pressure to 140°-150° C., with strong hydriodie acid, it 
yields caproic acid, iodide of ammonium, and iodine. 


C.H,,(NH,)COOH + 3 HI=C,H,, COOH + NH,I+1, 
(leucine) (caproic acid) 
2. Heated alone, rapidly over its melting-point (170° C.), to 180°-200° C., 
it yields amylamine and carbon-dioxide. 


C;H,,(NH,)COOH = C,H,,NH, + CO, 


3. When acted upon by nitrous acid, it breaks up in the usual manner of 
amido-acids, all the nitrogen being evolved as such, and oxycaproic or leucic 
acid being simultaneously formed. 


C,H,,(NH,)COOH + HNO, = C,H,,(OH)COOH + H,O+N, 


(leucine) (leucic or oxycaproic acid) 


These reactions show that leucine is an amidocaproic acid, but there are 
several isomeric amidocaproic acids.? It was thought until quite recently 
that leucine was the amido-acid of normal eaproic acid, but it has been recently 
shown to be amido-isobutylacetic acid. The difference in the structure of these 
two compounds would be represented according to the usual convention by the 
two following graphic formule :— 


CH, CH, -Ciig 
CH, 
Normal a-amido- | CH, Isobutyl-(a) amidoacetic CH 
caproic acid |CH, acid, or leucine CH, 
CH—NH, CHNH, 
COOH COOH 


Pure leucine crystallises in the form of thin white transparent plates, 
forming in mass a snow-white powder, which feel greasy and are not wetted 


1 Chem. Centr.-Bl., Leipzig, 1869, S. 159; Journ. f. prakt. Chem., Leipzig, 1870, 
Bd. i. S. 6. 

? According to R. Cohn, not one but several leucines are formed in pancreatic digestion ; 
these are probably the isomeric amidocaproic-acids, Zéschr. f. physiol. Chem., Strassburg, 
1894, Bd. xx. 8. 203. 

3 Schulze and Likiernik, Ber. d. deutsch. chem. Gesellsch., Berlin, 1891, Bd. xxiv. S. 669 ; 
Bb. Gmelin, Inaug. Diss.; Tiibingen, 1892. 


AMIDO-ACIDS FORMED IN TRYPTIC DIGESTION. 423 


by water, so that they float on its surface, although their specific gravity is 
about 1°3 ; but usually leucine is found to separate from solutions containing 
it in characteristic globules of microscopic size, often exhibiting a radial 
striation, or a marking off into concentric alternately dark and light bands. 
In this latter impure form it is easily soluble in water, and fairly so in 
alcohol ; the pure product is less soluble, its solubility is variously stated from 
1 in 29 to 1 in 47 parts of water at room temperature. This difference is 
usually ascribed to the presence of different isomeric modifications in varying 
proportions. 

Heated slowly to 170° C., leucine melts and commences to sublime in loose 
woolly flocks, resembling those formed when zine is burnt to zinc oxide ; these 
present the appearance microscopically of thin plates grouped into rosettes. 
Leucine is very feebly soluble in strong alcohol (about 1 in 1000 in 98 per cent. 
alcohol), and is insoluble in ether. 

The artificial leucine obtained as described above is inactive; so is that 
obtained by the action of barium hydrate on proteids at high temperatures 
(150°-160° C.). Leucine from the tissues is dextrorotatory, but also becomes 
inactive when heated to 150° C. with baryta water. When Penicillium 
glaucum is sown in inactive leucine, the organism lives on the dextrorotatory 
variety, and laevorotatory leucine is left behind. These two are physical isomers 
of each other ; their specific rotatory powers are (a)-D= + 17:3 for the right- 
handed, and (a)-D = — 17°5 for the left-handed. 

Tests for leucine.—Leucine may be recognised— 

1. By its crystalline form in the above-described spherules, forming from 
solution, and yielding a woolly sublimate which shows rosettes of platelets 
under the microscope. If it be heated rapidly so as to raise the temperature 
much above 170°, in subliming it the odour of amylamine is obtained. 

2. By dissolving in boiling water and adding boiling solution of cupric 
acetate, when a deep blue coloured crystalline compound appears. 

3. By Scherer’s test, which consists in adding a drop of nitric acid and 
slowly evaporating on platinum foil, when a nearly colourless residue is left. 
If this be wetted with sodium hydrate and gently heated, it forms into an oily 
globule which rolls about on the foil. 

Tyrosine.—Tyrosine, or para-oxyphenyl-a-amidopropionic acid (C,;H,(OH) 
CH,CH(NH,)COOH), is the almost constant companion of leucine in the 
decomposition of proteids. Unlike leucine, tyrosine is never found as a con- 
stituent of jresh tissues ; its supposed presence in fresh pancreas has been 
shown to be due to self-digestion of the gland,’ and it is not found in other 
fresh tissues, but is a constant constituent of those in which proteid decom- 
position has set in. It occurs very plentifully in old cheese, from which it 
was first obtained by Liebig by fusing with caustic potash. 

Tyrosine may be obtained in general by the same methods as leucine, but 
it is not formed in the decomposition of gelatin nor of antipeptone. 

Constitution of tyrosine.—The constitution of tyrosine has been established 
mainly by the work of von Barth,*® who first showed that tyrosine yielded on 
fusing with caustie potash para-oxybenzoiec acid, an isomer of salicylic acid. 
Previously to this, tyrosine had been looked upon as a derivative of salicylic 
acid, but from this von Barth concluded it must be ethylamido-para-oxy benzoic 
acid (C,H,.NH.C,H,.OH.COOH). If this formula were correct, on treating 
with hydriodic acid, ethylamine (C,H,.NH,) ought to be obtained, but Hiifner 
showed that ammonia instead was split off. Von Barth next found that the 


1 Schulze and Boshard, Ztschr. f. physiol. Chem., Strassburg, 1885, Bd. ix. S. 63 ; 1886, 
Bd. x. 8. 134. : 

2 Radziejewski, Virchow’s Archiv, 1866, Bd. xxxvi. S. 1; Kiihne, Untersuch. a. d. 
physiol. Inst. d. Univ. Heidelberg, Bd. i. 8. 317. 

5 Ann. d. Chem., Leipzig,, Bd. cli. S. 100. See also Erlenmeyer u. Lipp, Ber. d. deutsch. 
chem. Gesellsch., Berlin, 1882, Bd. xv. 8S. 1544. 


424 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


NH, group in his reaction was not replaced by hydrogen but by hydroxyl, 
and so finally arrived at the formula C,H,.OH.C, »H,(NH,)COOH, which is 
in agreement with all the experimental facts, and is now universally accepted. 

When fairly pure, tyrosine crystallises in long slender needles, which occur 
both singly and in double sheaves or in rosettes. If impure, however, it very 
often separates in balls or nodules closely resembling those of leucine, 
recrystallising from warm water in the crystalline form above described ; if 
the solution containing the crystals be filtered, these felt themselves together 
on the surface of the paper to a thin, snow-white, paper-like mass. Tyrosine 
is much more insoluble in water than leucine (1 in 1900 of cold water), more 
so (1 in 150) in boiling water and in dilute and concentrated mineral acids, 
and also in alkaline solutions (ammonia, alkalies and their carbonates, and the 
alkaline earths). Tyrosine exhibits the usual facility of amido-acids for 
forming compounds, both with bases and acids; the copper compound is 
sparingly soluble in water, and is formed in dark blue needles on the addition 
of freshly precipitated cupric hydrate to a boiling solution of tyrosine, and 
allowing to cool. 

Tyrosine, unlike leucine, cannot be sublimed without decomposition, and on 
dry distillation yields carbon-dioxide and a base of the composition C,H,,NO. 

Tests jor tyrosine.—Tyrosine may be identified by the following tests :— 

1. Its crystalline form. 

2. Scherer’s test, which consists in evaporating a portion with strong nitric 
acid in a platinum dish, leaving a transparent deep yellow residue, which 
turns red on moistening with caustic soda solution, and then a blackish brown 
on again evaporating. 

3. Piria’s test.—A drop or two of strong sulphuric acid is added to the 
tyrosine in a watch-glass ; after half-an-hour, during which tyrosine sulphurie 
acid forms, the acid is diluted with water, and neutralised by the addition of 
calcium carbonate. The solution is filtered from the calcium sulphate so 
formed, and a drop of neutral ferric chloride solution added, when a deep 
violet colour appears, similar to that given by salicylic acid. 

4. R. Hojfmann’s test.—This is reaily identical with the Millon test for 
proteids, and in cases where there is no group present in the proteid molecule 
capable of yielding tyrosine, the test with Millon’s reagent does not succeed, 
é.g., in the case of gelatin and of antipeptone. The test may be carried out 
directly in the case of tyrosine itself, by boiling a solution containing this with 
Millon’s reagent, when the solution passes through pink into deep crimson. 

Separation of leucine and tyrosine.—Leucine and tyrosine may very easily 
be separated when in solution together by means of their very different 
solubilities. To separate them after pancreatic digestion, it is best to allow 
digestion to proceed for several days; at the end of this time there is no 
coagulable proteid, or albumose, except in traces, left in the solution. This is 
neutralised and evaporated down, when the tyrosine, on account of its sparing 
solubility in water, is thrown out in crystalline masses, while the more soluble 
leucine nearly all remains in solution ; on cooling, more of the tyrosine separates 
out, and when the solution is cold it is filtered off, extracted with hot alcohol 
to remove traces of leucine, and purified by recrystallisation from hot water, 
or by dissolving in weak ammonia and precipitating by neutralisation. 

The filtrate containing the leucine and peptone is still further evaporated 
until it becomes syrupy ; it is then extracted with boiling alcohol, which takes 
up only the water and leucine. On evaporating off the alcohol, leucine is thrown 
out of the concentrated solution, and may be purified by sublimation or by 
repeated recrystallisation from alcohol. More tyrosine may be obtained from 
the residue left by the boiling alcohol. 

Or the solution, after completion of digestion and careful neutralisation, 
may at once be evaporated to a thin syrup and set aside for twenty-four hours, 


j 


AMIDO-ACIDS FORMED IN TRYPTIC DIGESTION. 425 


during which time most of both the leucine and tyrosine crystallises out. After 
separation of the crystals, the filtrate may be once more reduced in bulk by 
evaporation and a second crop of crystals obtained as before. 

To the syrupy mother-liquor now remaining absolute alcohol is added, until 
precipitation of the peptone commences, when the addition of alcohol is 
stopped and the precipitate of peptone redissolved by gently warming. The 
solution is now set aside to cool and erystallise as before. The united crops of 
erystals of mixed leucine and tyrosine are boiled with alcohol, which dissolves 
the leucine and but little of the tyrosine. On concentrating this alcoholic extract, 
leucine crystallises out and may be purified by recrystallisation from alcohol. 
From the residue insoluble in alcohol the tyrosine is obtained by dissolving in 
weak ammonia water and neutralising. 

The yield, both of leucine and tyrosine, obtained from different materials 
varies greatly, but in all cases the former is always formed in much larger 
quantity. The following table! gives the percentage yield of the substances 
obtained in some cases ; the figures indicate parts per 100 :— 


Source. Leucine. Tyrosine. | Observers and Method. | 
Gelatine . : . | 15-2 (a) | None (a) | (a) Nencki, boiling with dilute 
sulphuric acid. 
Ligamentum nuche | 36-45 (b) | 0°25 (bd) (6) Erlenmeyer and Schiffer, boil- 


ing for some hours 1 pint of 
material, 2 pints sulphuric 
acid, 3 pints water. 
Fibrin. : - | 14:0 (bd) 2°0 (6)-3°3 (e) | (c) Hlasiwetz and Habermann, 
heating with bromine un- 


|. der pressure. 
| Muscle . : ; 18:0 (5) | 1-0 (6) (d) Stédeler, heating with sul- 


| phurie acid. 
jebtorn  ) . ; - | 10°0-(6) | 3°6 (b)-4:0 (d) | (e) Schutzenberger, heating with 


| baryta water for four to six | 
days, at 160°-200° C. 


fibrin. 


| 


Aspartic acid, or amido-succinic acid [C,H,.(NH,).(COOH),|, does not 
occur in any of the animal tissues or secretions, but is formed in small 
quantity in all those decompositions of proteids and their allies already described 
as furnishing leucine and tyrosine.? It was first identified among the products 
of pancreatic digestion of fibrin by Radziejewski and Salkowski,? and von 
Knieriem afterwards showed that it is also formed in the pancreatic digestion 
of plant glutin. 

It may also be obtained by decomposing asparagin (amido-succinamic acid) 
by an alkali or acid, thus :— 


CH,—COOH CH,—COOH 


| Egg albumin . | 22,6 (e) | 1:0 (6)-2°0 (e) 

| Plant albumin Fe fe Wiese), 2°0 (e) 

| Casein . ; : | 19-1 (c) 4-1 (e) | 
| Fibrin Lot S. Gh) 3°3(f) | (f) Kiihne, digestion of boiled 


= +NH,Cl. 
CH(NH,)—CO(NH,)+HCI+H,O CH(NH,)—COOH 


(asparagin or amido-succinamice acid). (aspartic acid or amido-succinic acid). 


1 Compiled from Maly, Hermann’s ‘‘ Handbuch,” Bd. v. (2), S. 209 et seq. 

? Ritthausen and Kreuster, Journ. f. prakt. Chem., Leipzig, 1871, Bd. iii. S. 314; 
Hlasiwetz and Habermann, Ann. d. Chem., Leipzig, 1871, Bd. clix. S. 304. 

3 Radziejewski and E. Salkowski, Ber. d. deutsch. chem. Gesellsch., Berlin, 1874, Bd. vii. 
S. 1050 ; Ann. d. Chem., Leipzig, 1873, Bd. clxix. S. 150; W. v. Knieriem, Z¢schr. f. Biol., 
Miinchen, 1875, Bd. xi. S. 198. From 100 pts. of dry egg albumin Hlasiwetz and 
Habermann obtained 23°8 pts. of aspartic acid by the action of bromine in sealed tubes. 


426 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


Aspartic acid is soluble with difficulty in cold water, easily soluble in boiling 
water, and insoluble in aleohol.. It crystallises in rhombic prisms ; its solutions 
are optically active, and curiously when in acid solution it is dextrorotatory, 
but laevorotatory when in alkaline solution. It forms a crystalline compound 
with copper, which may be used for purifying it. After leucine and tyrosine 
have crystallised out from the products of a proteid decomposition, they 
are separated from the mother-liquors, and these are further concentrated 
and treated with a small quantity of alcohol, when after a time a new 
crust of crystals forms. These are dissolved in water, the solution is 
boiled with freshly precipitated cupric hydrate and filtered ; in the filtrate, 
on cooling, crystals are deposited of the copper salt of aspartic acid just 
mentioned. These crystals are dissolved in hydrochloric acid, the copper 
is thrown out by a stream of sulphuretted hydrogen, and the copper 
sulphide filtered off; in the filtrate, crystals of aspartic acid separate 
out. 

Glutamic acid is amido-pyrotartarie acid [C,H,.(NH,).(COOH),], and is 
homologous with aspartic acid, being the next higher member in the series, 
It occurs in minute quantities in the artificial decomposition of proteids, but 
has not yet been shown to be formed in the decomposition brought about by 
pancreatic digestion. It has been obtained by Ritthausen and Kreuster,! in 
the decomposition of vegetable proteid by dilute sulphuric acid ; from casein 
when decomposed by stannous chloride and hydrochloric acid, by Hlasiwetz 
and Habermann ;? and from reticulin, by Siegfried.® 

It may be obtained by saturating its ice-cold solution with hydrochloric 
acid gas, and then keeping in a freezing mixture until the compound with 
hydrochloric acid (C;H,NO,+ HCl) separates out in crystals, which are 
sparingly soluble in saturated hydrochloric acid, but easily soluble in water. 
Next, these crystals are dissolved in warm water, and the boiling solution 
is treated with freshly precipitated moist silver oxide, which removes the 
hydrochloric acid by forming silver chloride ; the filtrate is freed of silver 
by a stream of sulphuretted hydrogen, and concentrated. On standing, glutamic 
acid separates in crystals which form rhombic tetrahedra or octahedra, 
sparingly soluble in cold, readily soluble in hot water, but insoluble in 
aleohol or ether. Solutions of the acid are dextrorotatory (a2)D= +31°1, 
and it shows the same phenomena with regard to rotation as are described 
for leucine.* 

Organic bases formed in tryptic digestion.—Lysine and lysatine 
or lysatinine.—T wo organic bases, lysine and lysatine or lysatinine, have been 
recently isolated from the products of artificial decomposition of proteids, by 
means of a modification of the method of Hlasiwetz and Habermann, in which 
metallic zine was added in addition to stannous chloride and hydrochloric acid, 
and means taken to exclude oxygen during the operation. These substances 
were first isolated from casein by Drechsel,® and afterwards extensively studied 
by himself and others. They have since been found among the products of 
tryptic digestion.” 

Lysine and lysatine are both precipitated by a hot saturated solution of 
phosphotungstic acid, which does not precipitate the amido-acids, and so 
furnishes a means of separating the two from the other products of a proteid 

1 Journ. f. prakt. Chem., Leipzig, 1871, Bd. iii. S. 314. 

2 Ann. d. Chem., Leipzig, 1873, Bd. clxix. S. 150. 

3 ** Habilitationsschrift,’’ Leipzig, 1892. 4 See p. 423. 


5 Arch. f. Physiol., Leipzig, 1891, S. 254; Ber. d. deutsch. chem. Gesellsch., Berlin, 
1890, Bd. xxiii. S. 3096. 

6 EK. Fischer, Arch. f. Physiol., Leipzig, 1891, S. 265; Max Siegfried, Ber. d. deutsch. 
chem. Gesellsch., Berlin, 1891, Bd. xxiv. 8. 418; Arch. f. Physiol., 1891, 8. 270; S. G. 
Hedin, ibid., 1891, S. 273 ; Drechsel and Kriiger, Ber. d. deutsch. chem. Gesellsch., Berlin, 
1892, Bd. xxv. S. 2454. 

7 Hedin, Arch. f. Anat. wu. Physiol., Leipzig, 1891, S. 273. 


CHROMOGEN OF PANCREATIC DIGESTION. 427 


decomposition. Lysine forms a platinochloride (C,;H,,N,O,, H,PtCl,+ 
C,H,OH) which is insoluble in 50 per cent. alcohol, in which the corre: 
sponding lysatine salt is soluble, and by this means the two bases may be 
separated ; or they may be separated by means of the difference in solubility 
of their silver salts. 

Lysine, C,;H,,N,O.,, in composition corresponds to a diamido-caproic acid 
(C.H,(NH,),COOH) ; its solutions are dextrorofatory, but, like leucine and 
glutamic acid, become inactive when heated with baryta water to 150°C. The 
salts of lysine are crystalline, but the base itself has not been obtained in a 
crystalline form. 

Lysatine or lysatinine yields a crystalline silver salt of the composition 
C;H,,N,0,, HNO. + AgNO., from which the formula of the base follows as 
C;H,,N.,0.,, except, as is supposed probable, the silver salt contains a molecule 
of water of crystallisation, in which case the formula of the base would be 
C,H,,N,0. With the former formula it would be homologous with creatine, 
with the latter homologous with creatinine, and would be most properly 
called lysatine or lysatinine accordingly. 

Creatine is C,H,N,O, and creatinine is C,H-N,O0. The new base may be 
either lysatine with the formula C,H,,N,O,, or lysatinine with the formula 
C,;H,,N.,0 ; in either case being the second higher number in a homologous 
series, that is differing in formula by (CH,),. 

Another similarity to creatine invests this organic base with its most 

important physiological interest. Creatine when boiled with baryta water 
splits up into sarcosin (or methyl-glycocoll) and urea; similarly treated, 
lysatine also yields urea. Drechsel treated the lysatine obtained from 
10 grms. of the silver salt above referred to with excess of baryta water, 
and obtained 1 grm. of urea nitrate, from which he isolated and identified 
the urea. This is all the more interesting from the fact that creatine, 
although it occurs in the body under such circumstances as leave little 
doubt that it is formed as a decomposition product of proteids, has not 
“yet been obtained artificially as a direct product of proteid decomposition. 
Lysatine has not only been so obtained, but also as a product of pancreatic 
digestion, and urea having been obtained from this, has consequently been 
obtained as a product of proteid decomposition. 

Hedin? obtained from 3 kilos. of moist fibrin, 28 grms. of pure platino- 
chloride of lysine, and enough of the silver salt of lysatinine to establish 
its identity. 

Ammonia is found as a constant product in the artificial decomposition of 
proteids, as might be inferred from what has been stated concerning lysatine, 
and its formation has also been shown in pancreatic digestion. Hirschler * 
has shown that in the entire absence of putrefaction, in so short a period as 
four hours, small quantities of ammonia appear in the pancreatic digestion of 
fibrin ; this result has been confirmed by Stadelmann.+* 

The chromogen of pancreatic digestion.—As early as 1831 it was 
observed, by Tiedemann and Gmelin,’ that the pancreatic juice of the dog takes 
on a rose-red colour when mixed with chlorine water. Claude Bernard next 
showed that no such reaction is obtained with fresh pancreatic juice, but first 
appears after the juice has been kept for some time without putrefaction setting 
in ; if putrefaction takes place, the reaction is also not obtained. The product 
giving this colour reaction is now definitely recognised as a product of pancreatic 
digestion, and not a constituent of pancreatic juice. For it the name trypto- 


1 For details of these processes see Gamgee, ‘‘ Physiological Chemistry,” London, 1893, 
vol. ii. p. 255. 

* Arch. f. Anat. u. Physiol., Leipzig, 1891, S. 273. 

3 Ztschr. f. physiol. Chem., Strassburg, 1880, Bd. x. S. 302. 

4 Ztschr. f. Biol., Miinchen, 1888, Bd. xxiv. S. 261. 

> “Die Verdauung nach Versuchen,” Heidelberg, 1831. 


428 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


phan has been suggested by Neumeister,! from the point of view that 
it may be made to serve as an indicator of when tryptic digestion has 
reached a certain stage and amido-acids are beginning to be formed,” since 
it first appears in the more advanced stages of proteid decomposition simul- 
taneously with the amido-acids. Tryptophan has never been isolated, and is 
only known by its colour reactions. When not very dilute, the rose-red colour 
is replaced by violet, and Kiihne has shown that the colour is given by 
bromine water as well as by chlorine water. According to Krukenberg,? 
the colour is not due to oxidation by the chlorine or bromine, but to the 
formation of an addition compound; he also states that tryptophan is 
slightly soluble in alcohol, ether, and chloroform. Hemala* has shown that 
the coloured material is easily soluble in amylalcohol. Here chlorine and not 
bromine water must be used as a test, for the latter itself imparts colour to 
amyl alcohol. When much peptone or other impurity is present with it in 
solution, it falls, after some time, asa precipitate; this on shaking up with 
aleohol gives a fine violet solution showing an absorption band at the 
D line. According to Krukenberg, a strong coloration is given even by 
traces of the chromogen ; he also has shown that tryptophan is diffusible. 

In its reaction with bromine and chlorine water, tryptophan closely 
resembles the chromogen of the suprarenal gland; the two chromogens are 
also alike in being diffusible and in their powerful tinctorial action, but here 
resemblance ceases. The chromogen of suprarenals is very easily destroyed by 
alkalies, could not be formed in pancreatic digestion, and is quite insoluble in 
dry alcohol, ether, or chloroform. 

Kiihne has shown that tryptophan is a constant product in all proteid 
decomposition, but that it is rapidly destroyed and disappears; it is also 
rapidly destroyed by putrefactive changes. 

When pancreatic digestion is accompanied by putrefaction, many other 
substances are formed besides those above described. These will be considered 
in connection with bacterial digestion in the intestine. 


DIGESTION OF VARIOUS BODIES ALLIED TO THE PROTEIDS. 


Those substances, such as the mucins and nucleo-proteids, which 
consist of a proteid molecule united to some organic radicle (and called 
Proteide by Hoppe-Seyler), first undergo a cleavage into proteid and the 
body involved with it; the proteid is then digested in the usual fashion, 
while the other substance very often suffers no change. In this manner 
heemoglobin is decomposed by peptic digestion into a proteid commonly 
supposed to be a globulin, which becomes converted through albumose 
into peptone, and hematin which remains unchanged. Nucleo-proteids 
and nucleo-albumins® yield on similar treatment an insoluble residue 
of nuclein, or of pseudo-nuclein or paranuclein respectively, and the 
proteid part of the molecule is peptonised. In the tryptic digestion of 
fibrin some of the xanthin bases (or nuclein bases) have been found ; 
these arise from the breaking up of nuclear-nuclein (Kernnuclein) 
present as a constituent of admixed nucleo-proteid, derived from the 
nuclei of white blood corpuscles. The nuclein breaks up into nucleic 


1 Zischr. f. Biol., Miinchen, 1890, Bd. xxvii. S. 309. 

2The name proteinochromogen has been given to this chromogen by Stadelmann, 
ibid., 1890, Bd. xxvi. S. 491. 

3 Krukenberg, Virchow’s Archiv, 1885, Bd. ci. S. 555; Verhandl. d. phys.- med. 
Gesellsch. zu Wiirzburg, 1884, 8. 179. ; 

4 Loc. cit. See also Neumeister, Zischr. f. Biol., Miinchen, 1890, Bd. xxvi. S. 332. 

5 Nucleo-proteids yield on decomposition a true nuclein, containing nucleic bases, 
nucleo-albumins a pseudo-nuclein or paranuclein, which does not contain such bases. 


DIGESTION OF BODIES ALLIED TO PROTEIDS. 429 


acids and proteid, and the nucleic acids in their turn into nuclein bases 
and phosphoric acid. These changes take place very slowly in tryptic 
digestion. On digestion with pepsin and hydrochloric acid, the glyco- 
proteids are decomposed, yielding a carbohydrate substance which 
reduces Fehling’s solution and a proteid which as before is peptonised. 
This decomposition only takes place slowly, .and is probably due in 
great part to the feeble hydrolytic action of the hydrochloric acid. 

The caseinogen of milk is first coagulated by the action of the rennin 
of the gastric juice, and afterwards the insoluble casein formed in this 
process is digested. 

Casein is broken up in the process of gastric digestion into a proteid 
and pseudo-nuclein, of which the former is changed into peptone, while 
the latter is thrown out as an insoluble precipitate. 


This precipitate corresponds to the dyspeptone of Meissner, and has been 
the subject of a considerable amount of investigation. Lubavin! found that 
it contained inorganic phosphorus, and that it is a mixture of which one part is 
soluble in dilute sodic carbonate (Na,CO,), while the other is insoluble. The 
soluble part contains 4°6 per cent. of phosphorus, and is probably identical 
with Hoppe-Seyler’s nuclein. Chittenden ? and others state that dyspeptone does 
not contain much phosphorus, and that this is probably present as calcium 
phosphate, dyspeptone being therefore not a nuclein but a mixture of calcium 
phosphate with a hydration product of casein. C. Wildenow® does not hold 
with this view, having obtained dyspeptone which contained only 0°13 
per cent. of calcium, and 3°85-4:66 per cent. of phosphorus, but agrees with 
Lubavin that the precipitate isa nuclein. E. Salkowski‘* supports this con- 
clusion ; he also announces that on prolonged digestion the precipitate 
redissolves to a clear solution, part of the phosphorus being split off as 
phosphoric acid, and part remaining in organic combination (probably as 
paranucleic acid). Such a solution can be brought about, according to 
Salkowski, by a strong peptic solution within forty-eight hours. 


The albuminoids as a class are fairly resistant to the action of 
digestive agents ; when they are broken up, they yield products closely 
resembling those furnished by the decomposition of the true proteids. 

Collagen is said to be converted into its hydrate gelatin more 
rapidly by the action of pepsin and hydrochloric acid than it would be 
by the acid alone; the gelatin thus formed is then acted upon by the 
pepsin and hydrochloric acid, and rapidly loses its characteristic property 
of gelatinising on cooling.» This physical change is the visible sign of a 
chemical one, by which the gelatin is converted into a substance called 
protogelatose ; this is again changed, yielding deuterogelatose ; and finally 
gelatin peptone is formed.® These substances resemble the corresponding 
compounds of proteid digestion, the gelatin peptone being distinguished 
from the other two products by its indifference to the saturation of its 
solutions with neutral salts and by its diffusibility. Protogelatose is 
thrown out of solution by saturation of its acidified solution with sodium 


1 Med.-chem. Untersuch., Berlin, 1871, S. 463. 

2 Stud. Lab. Physiol. Chem., New Haven, 1890, vol. iii. p. 66. 

3 Inaug. Diss., Bern, 1893. 

4 Centralbl. f. d. med. Wissensch., Berlin, 1893, Nos. 23, 28; Arch. f. d. ges. Physiol., 
Bonn, 1896, Bd. Ixiii. S. 401. ; 

5 J. de Bary, Zischr. f. physiol. Chem., Strassburg, 1896, S. 75 ; Etzinger, Zéschr. f. 
Biol., Mimchen, Bd. x. 8. 84; Uffelmann, Deutsches Arch. f. klin. Med., Leipzig, Bd. xx. 
S: 535: 

6 Chittenden and Solley, Journ. Physiol., Cambridge and London, 1891, vol. xii. p. 23. 


430 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


chloride, while deuterogelatose is only precipitated by saturation with 
ammonium sulphate. Protogelatose is also precipitated by platinic 
chloride, while deuterogelatose is not so precipitated. 

Collagen is not attacked by pancreatic juice unless it has been 
previously boiled with water, or swollen by the action of dilute acids, as 
it normally would be by the gastric juice! This result is confirmed by 
the observation of Ludwig and Ogata, that after removal of the stomach 
proteid was still digested, | but connective tissue was not attacked. After 
such preliminary treatment collagen is easily converted into gelatin, 
and the after course of events closely resembles that described for 
peptic digestion. There is first formed protogelatose, then deutero- 
gelatose, and finally gelatin peptone, which is not converted by any 
further action of trypsin into amido-acids.2. Trypsin acts so easily on 
gelatin, and deprives it so readily of its power of gelatinising, that this 
has been recommended by Fermi as a test for trypsin.® 


The decomposition products of gelatin have been long known, though not 
with the exactitude above described. Gmelin showed that it was decom- 
posed by superheated steam at 140° C., and Hofmeister * obtained, after boil- 
ing with water in 1 per cent. solution for thirty hours, two cleavage products 
which he termed semiglutin and semicollin ; these are probably identical with 
proto- and deuterogelatose. 


Elastin is also dissolved by pepsin and hydrochloric acid,’ though 
with more difficulty than collagen. The products of the peptic digestion 
of elastin were studied by Horbaczewski,® who described two products 
which he called hemielastin and elastin peptone. The same subject has 
been investigated more recently by Chittenden and Hart,’ who have 
shown that two substances are formed in the peptic digestion of elastin, 
but that both these substances are albumoses, since they are both pre- 
cipitated by saturation of their solutions with ammonium sulphate ; to 
these substances they gave the names of protoelastose and deutero- 
elastose. The former is precipitated on saturation of its solution with 
sodium chloride, while the latter is only precipitated on the addition of 
acetic acid. Elastin is also directly attacked by trypsin and dissolved, 
forming in turn proto- and deuteroelastoses as in peptic digestion, but 
neither in peptic or tryptic digestion is there any peptone formed. 


1 Ewald and Kiihne, Verhandl. d. naturh.-med. Ver. zw Heidelberg, 1877, N. F., 
Bd. i. S. 451. 

2 Chittenden and Solley, Joc. cit. 

3 Arch. f. Hyg., Miimchen u. Leipzig, 1891, Bd. xii. 

4 Ztschr. f. physiol. Chem., Strassburg, 1878, Bd. ii. S. 299. 

5 Etzinger, Ztschr. f. Biol., Miinchen, Bd. x. S. 84. 

6 Zischr. f. physiol. Chem., Strassburg, 1882, Bd. vi. S. 330. 

7 Ztschr. f. Biol., Miinchen, 1889, Bd. xv. S. 368. 

8 Chittenden and Hart, Joc. cit. 


ABSORPTION OF CARBOHYDRATES AND PROTEIDS. 4 


31 


THE ABSORPTION OF CARBOHYDRATES AND PROTEIDS. 


It was for many years believed that the absorption of the products of 
digestion from the alimentary canal was governed by exactly the same 
physical laws as determine the passage of a solution and its dissolved 
constituents through an inert membrane, but the accumulation of 
experimental evidence has rendered such a belief no longer tenable. 
It is now known that the cells which line the alimentary canal take an 
active part, not only in absorbing the materials prepared for them by 
the action of the digestive secretions, but in modifying these products 
in various ways during the process. 


Before the laws of diffusion of solutions were known, the process of 
absorption by the columnar cells of the intestine was compared by Tiedemann 
and Gmelin (1820)! to that of gland secretion. After the establishment of the 
laws of diffusion, attempts were made to apply them in explanation of absorp- 
tion, as well as of other similar processes in the body. Such physical views 
persisted for a long time, until it was shown by conclusive experiments that 
absorption, like these other processes, does not obey the laws of physical 
diffusion, but is selective in its character and governed in some subtle way 
by the activity of the cells involved. Our modern view is thus, as is often 
the case, a recurrence to an older theory; the only difference being that we 
have a somewhat broader experimental basis on which to build it. 

The cells of a secreting gland take up certain materials from the lymph in 
which they are bathed, and from these, in some manner, elaborate certain 
products which are passed into the gland lumen as a secretion. Similarly, the 
absorbing cells of the intestine take up certain products of digestion from 
the intestinal contents by which they are bathed, and build up from these 
certain materials which pass into the lymph. So that absorption may be 
regarded as a kind of reversed secretion. 

In both cases the process is a selective one, the constituents of the gland 
secretion are definite in their nature, in many cases specific, and are probably 
formed from definite constituents of the lymph taken up by the secreting cell 
to the exclusion of others. In like fashion, certain materials only are taken 
up by the epithelial absorbing cell, and from these definite products are 
formed to be passed into the lymph. 


That absorption is a selective process and not one of purely physical 
diffusion, is shown by the following observations :— 

1. Certain colloids (e.g. alkali albumin) disappear from the intestine 
at a fairly rapid rate, even in the complete absence of digestive 
enzymes.” 

2. The rate of absorption from the intestine of various dissolved 
substances is not proportional to their diffusion-coefficients. Sodium 
sulphate is much more diffusible than grape-sugar, but when a solution 
containing 0°5 per cent. of each of these is injected into the intestine, 
the sugar disappears much more rapidly, and only traces of it remain 
at a time when the greater part of the sodium sulphate is still left 
behind.* 

3. The rapidity of absorption is much greater than can be accounted 


1 Quoted by Heidenhain, Arch. f. d. ges. Physiol., Bonn, 1888, Supp. Heft, Bd. 
xliii. S. 69. 

2 See form of absorption of proteids, p. 436. 

?Rohmann, Arch. f. d. ges. Physiol., Bonn, 1887, Bd. xli. 8, 411. 


432 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


for, on the basis of physical diffusion from the intestinal contents to the 
lymph.t 

4. If the dissolved products of digestion are carried through by 
diffusion, it must be passively in a diffusion stream due to salt diffusion, 
their own diffusive powers being too feeble to suppose they are carried 
by these. Now, not only would such a stream be too slow, but, in such 
a case, the amount of fluid which must be absorbed by the epithelial 
cells would be enormous. There is at the height of proteid digestion, 
even in an animal with such digestive powers as the pig, rarely more 
than 2 per cent. of albumoses and peptones together in solution in the 
intestine, and usually much less. If it be supposed that this is passively 
and not selectively absorbed, then to carry 100 grms. of digested proteid 
out of the intestine, 5 litres of water at least, and probably a great 
deal more, would be required. During the digestion of starch, only 
traces of sugar are found at any given time in the intestine, and 
generally it may be stated that absorption takes place from very dilute 
solution. There is no reason to believe that such enormous quantities 
of fluid are thrown into the intestine during digestion, to be afterwards 
absorbed from it, and hence it must be concluded that dissolved 
substances are not passively absorbed by their solutions passing 
unchanged into the epithelial cell. 

Seat of absorption.—Absorption of some substances begins in the 
stomach? but the main part takes place in the intestine. Water is 
practically not absorbed at all in the stomach,? while alcohol is readily 
taken up. The absorption of chloral hydrate and of sugar by the 
stomach is increased by the presence of alcohol. 

Gastric absorption is said to be increased by greater concentration of 
the substance to be absorbed, while the reverse holds for intestinal 
absorption. A solution of grape-sugar is most rapidly absorbed from 
the intestine when its concentration lies at 0°5 per cent.; as the 
concentration increases from this the rate of absorption diminishes ; 
while the rate of absorption in the stomach increases up to a concen- 
tration of 20 per cent. According to v. Mering, all forms of sugar are 
absorbed in the stomach to a greater or less extent. The products of pro- 
teid digestion are also probably absorbed toa slight extent in the stomach.? 

Channels of absorption.—The new materials formed by the action 
of the intestinal epithelial cells on the absorbed products of digestion, 
pass out of these cells into the lymphoid tissue of the villus underlying 
them. The modified carbohydrates and proteids pass in solution into 
the lymph which bathes the tissue, and in soluble form are absorbed 
from this lymph by the capillary vessels of the villus, thus passing 
directly into the portal circulation, while the fats leave the epithelial 
cells as fat globules, and are carried as such past the capillary network 
of the villus, to enter the lacteal situated in the axis of the villus.® 


1 Heidenhain, Arch. f. d. ges. Physiol., Bonn, 1888, Supp. Heft, Bd. xliii. 8. 70. 

2See Busch, Virchow’s Archiv, 1858, Bd. xiv. S. 171; Tappeiner, Zischr. f. Biol., 
Miinchen, 1880, Bd. xvi. S. 497; v. Anrep, Arch. f. Anat. u. Physiol., Leipzig, 1881, 
S. 504; Meade-Smith, ibid., Leipzig, 1884, S. 481; v. Mering, Verhandl. d. Cong. f. 
innere Med., Wiesbaden, 1893; Centralbl. f. Physiol., Leipzig u. Wien, 1893, Bd. viii. 
S. 533. 

’ Edkins, Journ. Physiol., Cambridge and London, 1892, vol. xiii. p. 445 ; v. Mering, 
loc. cit.; Gley and Rondeau, Compt. rend. Soc. de. biol., Paris, 1893, p. 516. 

4 Brandl, Ztschr. f. Biol., Miinchen, 1892, Bd. xxix. S. 277. 

5 See F. Hofmeister, Zischr. f. physiol. Chem., Strassburg, 1882, Bd. vi. S, 69. 

5 See ‘* Digestion and Absorption of Fats,” p. 457. 


ABSORPTION OF CARBOHYDRATES AND PROTEIDS. 433 


There are thus two channels of absorption leading to the systemic 
blood stream. One by the capillaries of the villus, passing through the 
liver; the other by the lacteals, vid the abdominal lymphatics, to the 
thoracic duct leading directly to the subclavian vein. 

Absorption of water—It has been shown by Heidenhain! that by 
far the greater share of the water absorbed from the small intestine 
is taken up by the capillaries of the villus and not by the lacteals. 
When large quantities of dilute saline solution (0°3 per cent.) are injected 
into the small intestine, the rate of lymph flow in the thoracic duct 
is not markedly increased, unless so much salt solution is injected at one 
time that the intestine becomes forcibly distended. Zawilsky” also 
found that even during active fat absorption there was no great increase 
in the amount of lymph flowing from the thoracic duct; the lymph 
became charged with an exceedingly fine emulsion of fat, but was not 
largely increased in quantity. 

The considerable absorption of water which commences in the lower 
end of the ileum, and goes on throughout the entire length of the large 
intestine, causing the thin chyme of the upper part of the small intestine 
to become semi-solid, and finally to assume the consistency of the feces, 
is also carried out by the agency of capillary blood vessels, so that 
practically all the water absorbed from the intestine is taken up by the 
blood stream. The blood is not diluted to a corresponding extent in the 
process; in fact, even with the absorption of an excessive amount of 
water, as in Heidenhain’s experiments above quoted, the composition of 
the blood is little altered. The absorbed water in such a case of 
excessive absorption passes at first into the lymph which bathes the 
tissues, to be afterwards brought out and gradually eliminated by the 
kidneys as the excess in the blood diminishes. 

Absorption of soluble constituents.23—All those substances which leave 
the epithelial cell in solution, are also carried away from the lymph 
spaces of the villus by the capillaries* This has been shown chiefly by 
observations made during active absorption of these several constituents, 
on the rate of flow in the thoracic duct, the constitution of the lymph so 
flowing, and the effects of ligature of the duct or diversion of the stream 
to the exterior. Direct analyses of the blood of the portal vein, as com- 
pared with the systemic blood, do not yield trustworthy results ; partly 
because of the difticulty of making very exact determinations in such a 
complex fluid as blood serum ; still more because of the very small change 
in composition which is sufficient to account for the carriage of a great 
weight of absorbed substance, by reason of the copious flow which takes 
place through the capillaries, especially when active digestion is in 
progress. 

If a cannula be inserted into the upper end of the thoracic duct, and 
the rate of flow of the lymph stream measured, as well as the amount of 
proteid contained therein, neither of these is found materially to alter, 
whether the animal (dog) be fasting, or active proteid digestion be going 


F 1 Arch. f. d. ges. Physiol., Bonn, 1888, Supp. Heft, Bd. xliii. S. 53; 1894, Bd. lvi. 
SEYCE 

2 Arb. a. d. physiol. Anst. zu Leipzig, 1876, Bd. xi. S. 161. 

3 For the Absorption of fats and fatty acids, see p. 443. : 

4It is often stated that all the dissolved intestinal contents are so absorbed, but if, as 
is probable, fats are absorbed in soluble form, such a statement is obviously incorrect. Only 
those constituents which remain soluble, after the action of the absorbing cells, pass into 
the capillaries. 


VOL. 1.—28 


434. CHEMISTRY OF THE DIGESTIVE PROCESSES. 


on. This could obviously not be the case if any appreciable part of the 
proteid were absorbed by the lacteals. 

Again, if the thoracic duct be ligatured, and an hour after the opera- 
tion the animal (dog) be given a tich meal of proteid food, absorption 
goes on in a normal manner. If the animal be killed after the lapse of 
about forty-eight hours, it will be found that all the proteid has been 
absorbed, while a corresponding amount of nitrogen has been eliminated 
in the urine.! 

A similar proof has been given for carbohydrate absorption by the 
blood vessels. In this case the animal is fed with carbohydrate food 
instead of proteid; and the amount of sugar in the lymph which flows 
from a fistula of the thoracic duct is estimated. The percentage of sugar 
lies between 0°6 and 1:6 per thousand, and does not vary in the least 
with the state of digestion, this being the usual percentage of sugar 
found in lymph or blood serum.2 

A direct proof has also been given of the absorption of sugar by the 
capillaries, as it has been shown that on injection of sugar into the 
intestine the percentage of sugar in the portal vein may rise as high 
as 4 per 1000, while in a fasting condition the amount of sugar 
contained in the blood of either por tal or hepatic veins does not essentially 
differ from that in the blood of the remainder of the circulation.? 

It may be taken, then, that, under normal conditions, all the soluble 
constituents which leave the epithelial cell are taken up by the capillaries. 
But when excessive absorption is taking place, as when large quantities 
of sugar in concentrated solution are injected into the intestine, this is 
not the case. Here the work of absorption becomes too great for the 
capillaries, a part of the dissolved foodstuff passes the region of their 
action and is absorbed by the lacteals, probably in a passive “fashion. 

Conditions of absorption of serge ine —There is no doubt 
that a considerable share of the carbohydrate food is taken up from 
the intestine by the absorbing cells as simple sugars (mainly as dex- 
trose and levulose), otherwise the reason of the ferment actions which 
have been previously described would be difficult to see. But we 
possess no experimental evidence to show that all the carbohydrate 
is absorbed in such a form. Indeed, it is probable that the absorbing 
cells are capable of taking up not only saccharoses, but even colloidal 

earbohydrates, such as dextrin and starch, and converting these into 
simple sugars before turning them into the blood stream. 

We have already seen, in discussing the digestion of starch and 
glycogen, that it is impossible, in experiments carried out in vitro, to 
further convert all the dextrin formed into maltose or other form of 
sugar. Sheridan Lea’s* experiments show, indeed, that the rapidity of 
diastatic action is much increased by dialysis, and the quantity of dextrin 
left unchanged into maltose largely diminished. Lea argues from this 
result that, under the more favourable conditions for removal of digestion 
products existing in natural digestion, the conversion of dextrin into 
maltose may become complete. Contrary to this view, there is the 
experience of Musculus and Gruber, that the unchanged dextrin remain- 
ing after a prolonged digestion of starch, with a diastatic ferment, is not 


1 Schmidt-Miilheim, Arch. f. Anat. u. Physiol., Leipzig, 1877, S. 549. 
2 Von Mering, ibid., 1877, S. 379. 
8 Journ. Physiol., Cambr idge and London, 1890, vol. xi. 2 226 ; see also pp. 321 and 394. 
4 Zischr. f. physiol. Chem., “Strassburg, 1878, Bd. ii. S. 177. 


ABSORPTION OF CARBOHYDRATES. 435 


convertible into maltose by a fresh addition of diastatic ferment after 
complete removal of the maltose produced by the first digestion. So 
that the failure of the ferment to convert the last portion of dextrin into 
maltose cannot be wholly due to the stoppage of its action by the presence 
of excess of maltose. 

There is no very evident reason why soluble materials like the dex- 
trins should not be absorbed as such by the epithelial cells. The argument 
that dextrin is not directly assimilable, because, when injected subcutane- 
ously or intravenously, it is eliminated by the kidneys, is not valid against 
its absorption as dextrin by the epithelial cell. Yor there is no reason to 
suppose that the cell must turn it into the lymph in exactly the same 
form in which it takes it up from the intestine; the chances are, in fact, 
all against such a supposition. It may be taken as probable, then, that 
the digestive enzymes of the alimentary canal are incapable of con- 
verting all the starch of the food into maltose, and hence into dextrose, 
and that a portion is absorbed as dextrin, and changed into something 
else before reaching the blood stream. 

What has been said above concerning dextrin applies also to the 
double sugars. The intestinal juice, as we have seen, contains enzymes 
capable of converting maltose and cane-sugar into simple sugars, and it is 
probable that such a change does take place to a very large extent. Still 
it cannot be concluded that the double sugars undergo complete conversion 
before absorption. Lactose appears not to be acted upon by any of the 
digestive enzymes, and so far as it escapes lactic acid fermentation this 
double sugar must be absorbed by the epithelial cell unchanged. Again, 
Brown and Heron?! found that the dried mucous membrane acted much 
more energetically on maltose than did any extract of it, which tends to 
show that this action takes place in part within the cell. 

Rohmann 2 has also shown that not only sugar, but even starch solution 
disappears from a Thiry-Vella fistula with considerable rapidity ; and as 
the succus entericus possesses only an exceedingly feeble diastatic action 
on starch, it seems that here the starch must be directly taken up by the 
intestinal cell. Such a view is also supported by the fact that, after 
removal of the pancreas, the secretion of which must produce the greater 
part of the diastatic action which goes on within the intestine, one-half 
to three-fourths of the starch of the food is still utilised.4 Under normal 
conditions, however, the diastatic conversion by the pancreatic juice is so 
rapid, that it is very improbable than any appreciable portion of starch is 
absorbed as such. 

Form in which carbohydrates reach the blood stream.—During active 
carbohydrate absorption, traces of carbohydrates, resembling dextrin, are 
said to be present in the blood of the portal vein,* but it is probable that 
very little carbohydrate leaves the epithelial cells other than dextrose 
or levulose. These two sugars are capable of direct assimilation after 
subcutaneous injection, and of forming glycogen in the liver, but no such 
direct assimilation takes place in the case of cane-sugar or maltose. 


1 Loe. cit. 2 Arch. f. d. ges. Physiol., Bonn, 1887, Bd. xli. S. 411. 

3 Minkowski and Abelmann (Inaug. Diss., Dorpat, 1890; Centralbl. f. Physiol., 
Leipzig u. Wien, 1891, Bd. iv. S. 522) found, after complete extirpation of the pancreas, 
an absorption of 57-71 per cent. of starch ; the brothers Cavazzanni (Centralbl. f. Physiol., 
Leipzig u. Wien, 1893, Bd. vii. S. 217), under like circumstances an absorption of 47 per 
cent. 

4 Otto, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1888, Bd. xvii. S. 138 ; 
y. Mering, Arch. f. Anat. u. Physiol., Leipzig, 1877, S. 413. 


436 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


Ingestion of large quantities of solution of sugar leads to the appear- 
ance of sugar in the ure (alimentary glycosuria), due to the assimilation 
of the sugar not keeping pace with its absorption.1 Absorption itself 
is also disturbed by the appearance of diarrhoea. But when carbohydrate 
is introduced into the alimentary canal, in the form of starch, immense 
quantities can be rapidly and completely absorbed without any glycosuria 
or other disturbance ensuing. 

Thus Riibner? found that a man consuming a daily ration of 508-670 
gris. of carbohydrate contained in wheaten bread, left unabsorbed only 
08-26 per cent.; of the carbohydrate of peas (357-588 grms.) 3°6—7-0 per 
cent. was unabsorbed ; and of potatoes (718 grms.) 7 6 per cent. This 
complete absorption and utilisation of carbohydrate, when taken in the 
form of starch, is probably due to the rate of assimilation and storage as 
glycogen in the liver, being able to keep pace with that of absorption 
from the intestine. 

Conditions of absorption of proteids.—The power possessed by 
the intestinal cells of absorbing various forms of proteid affords one 
of the best illustrations that this process is not one of mere 
physical diffusion. The products found towards the end of a proteid 
digestion 7m vitro are distinguished from the proteids from which they 
originate by being slightly ‘diffusible. To this fact great importance 
was at one time attributed, because it was thought that only proteids 
in a diffusible form were capable of absorption, and hence that peptonisa- 
tion was in all cases a necessary preliminary. It is now generally 
admitted that many forms of native proteid are capable of entering the 
epithelial cells without previous change by digestion or otherwise ; and 
in those cases in which a proteid is incapable of direct absorption a much 
less profound change than peptonisation is sufficient to render it so, 
namely, conversion into acid or alkali albumin. Such an absorption of 
soluble proteid, other than albumose or peptone, takes place not only in 
the small intestine, but in the large intestine, and even in the rectum. 

Voit and Bauer® cleared a loop of small intestine of its contents as 
completely as possible by stroking, and separated it from the rest of the 
gut by double ligatures at each end. Various forms of proteid, in solu- 
tions of known amount and strength, were then injected into this loop ; 
the intestine was replaced, and its contents examined on killing the 
animal (cat or dog) some hours later. It was found that variable amounts 
of these proteids had disappeared; thus, in one to four hours, 16—33 per 
cent. of white of egg had disappeared, and of syntonin from ox muscle 
28-95 per cent. It might be supposed that the portion of proteid ab- 
sorbed had been peptonised by traces of proteolytic enzyme which might 
be present in the intestine; but in the unabsorbed proteid remaining at 
the end of the experiment, no albumose or peptone was found. Voit and 
Bauer also injected solutions of white of egg and sodium chloride into the 
rectum of man and animals in a fasting condition, and found a marked 
increase (6 to 8 grms. in 24 hours) in the amount of nitrogen eliminated 
by the kidneys; in fact, an equilibrium of nitrogenous metabolism may 
even be maintained in this way. It has been shown by Eichhorst,* who 
confirms these results, that no appreciable amount of peptonisation takes 


1C. Voit, Zschr. f. Biol., Miinchen, 1891, Bd. xxviii. 8, 245. 
2 Tbid., Bd. xix. 8. 45. 

® Tbid., Bd. v. S. 562. 

4 Arch. f. d. ges. Physiol., Bonn, 1871, Bd. iv. 8. 570. 


ABSORPTION OF PROTEIDS. 437 


place in the large intestine. Finally, the objection that the action is due 
to traces of enzymes, has been disposed of by the observations of Czerny 
and Latschenberger, ‘in a case of a fistula situated in the sigmoid flexure. 
The rectum was ‘thoroughly washed out from the fistula, yet from 60-70 
per cent. of the injected proteid disappeared in 25-29 hours. 

Assimilable and non-assimilable proteids—Some forms of proteid, such 
as alkali albumin, prepared from white of egg, and acid albumin, prepared 
from muscle, myosin, fibrin, or white of egg, are directly assimilable ; that 
is to say, when injected into the blood stream they are not removed again 
by the kidneys; others, such as unchanged white of egg, caselnogen, ‘and 
glutin, are, when injected, at once excreted i in the urine. The latter for ms 
must therefore, under normal conditions, be changed during absorption, 
before passing into the blood; but when excess of white of ego is present 
in the intestine, absorption oversteps the rate at which this ‘change can 
take place, and a portion of the egg albumin reaches the circulation 
unchanged. Under these circumstances, this portion is promptly re- 
moved by the kidneys, and an “alimentary albuminuria” is the result, 
just as an excessive amount of sugar in the intestine produces “alimentary 
glycosuria.” 

Relative amounts of proteids absorbed in different forms—It is 
evident, then, that absorption can take place, either in the form of 
albumose or peptone, of alkali or acid albumin, or even occasionally 
in that of native proteid; and the question arises, to what extent does 
absorption take place under natural conditions in each of these different 
forms? Such a question is exceedingly difficult to answer by experiment. 
It is impossible to do so exactly by observation of the amount of each 
form of proteid present in the intestinal contents during proteid absorp- 
tion, because the absorption is selective, and a substance present only in 
traces may be passing out of the imtestine more rapidly as it is con- 
tinuously formed than another which is present in much larger quantity. 

A rough estimate of the relative amounts of proteid absorbed as 
albumose and peptone, and that absorbed in other forms, may be obtained 
from analyses of the intestinal contents during proteid digestion. Thus, 
Schmidt-Miilheim ? examined the contents of the stomach and intestine 
at varying periods during digestion of flesh in dogs; he found that the 
amount of proteid in solution, both in the stomach and intestine, was 
small at any given time, but that the amount present as albumose and peptone 
was always somewhat greater than that present in other forms. When it is 
remembered that albumose and peptone are absorbed more rapidly than 
other proteids, this points to the greater part of the proteid being absorbed 
as albumose and peptone. 

It is not known with certainty to what extent amido-acids are formed 
from proteids, in the natural course of intestinal digestion. The experi- 
mental evidence on the subject is somewhat conflicting, but the majority 
of observers are of the opinion that but little proteid is absorbed as leucine 
and tyrosine, being nearly all absorbed as albumose or peptone, or even 
at a still earlier stage. 

The only positive evidence as to the formation of leucine and tyrosine 
in natural digestion, rests on the amounts found in the intestinal contents 


1 Virchow’s Archiv, 1874, Bd. lix. S. 174; see also Ewald, Ztschr. f. klin. Med., Berlin, 
1887, Bd. xii. S. 407; Huber, Deutsches Arch. f. klin. Med., Leipzig, 1891, Bd. xlvii. 
S. 495. 

2 Arch. f. Anat. u. Physiol., Leipzig, 1879, S. 39. 


438 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


during proteid digestion. Such evidence can only give a reliable 
estimate of the amount formed relatively to other proteid products, 
when the rate of absorption from the intestine of these various products 
is known. 

Kolliker and Miller! found only microscopic traces of leucine and 
tyrosine in the upper part of the small intestine of carnivorous animals, 
and none in the lower part. Kiihne? subjected fibrin to tryptic digestion 
in a tied-off loop of imtestine, into which the pancreatic duct entered, 
and subjected the residue to analysis after four hours. Leucine and 
tyrosine were found among the products, but the yield was small, and, 
moreover, the conditions in such an experiment are not quite comparable 
to those of natural digestion. Indeed, Kiihne himself thinks it probable 
that the greater part of the “peptone” being rapidly absorbed escapes 
such a decomposition. 


Schmidt-Miilheim ® states that, in proteid digestion in the carnivora, leucine 
and tyrosine are either not formed at all, or else in such small quantities that 
their absorption is of no physiological importance as a means of removing from 
the alimentary canal any appreciable amount of nitrogen derived from the 
proteid foodstuffs. 

On the other hand, Sheridan Lea* obtained from the intestinal contents of 
a dog, six hours after a plentiful meal of lean flesh, what must be regarded as a 
considerable amount of amido-acids to be found there at any given time (par- 
ticularly when it is remembered that the amount of intestinal contents in the 
dog at any given moment, even during active proteid digestion, is very scanty), 
namely, 1 germ. of pure leucine, and °3 grm. of tyrosine. These figures equal the 
total amounts obtainable of these products from 10 grms. of dried proteid, and 
if it be assumed that leucine and tyrosine are absorbed with a rapidity equal to 
that with which albumoses are taken up, indicate that a considerable percentage 
of proteid was being converted into amido-acids, and absorbed as such. 

The relative amount of proteid decomposed in the intestine into amido- 
acids, as well as that absorbed in the various other forms, probably varies within 
wide limits with the state of nutrition of the animal and the amount of proteid 
food. It is possible, as Foster® states, that such a degradation of proteid in 
the intestine may serve as a safety-valve to the economy, diverting from the 
tissues the burden of an often unnecessarily large proteid metabolism. The 
waste of energy to the animal economy caused by the disintegration of proteid 
into amido-acids in the intestine is often advanced as an argument against the 
occurrence of this process to any marked extent. Certainly the potential 
chemical energy of the proteid is lost to the economy, as far as the performance 
of some forms of physiological work is concerned, but it should not be forgotten 
that the ¢otal amount of energy abstracted by the animal from its food is 
measured by the chemical form in which it enters and that in which it leaves 
the body, and a given portion of proteid entering the body and then leaving it 
as urea, water, and carbon dioxide, will give up to the body exactly the same 
store of energy, no matter what may be the intermediate steps by which it is 
reduced from one form to the other. In one case the energy is set free in 
the tissues, in the other in the intestine. In the second case, the heat 
set free by chemical decomposition is communicated to the intestine and 
earried off by the circulating blood, to keep up the temperature of the body, 
thus sparing reserve chemical energy which would otherwise have to be used 
for this purpose. 


1 Verhandl. d. phys.-med. Geselisch. zu Wiirzburg, 1856, Bd. vi. S. 499. 

2 Virchow’s Archiv, 1867, Bd. xxxix. S. 130. ® Loe. cit. 
4 Journ. Physiol., Cambridge and London, 1890, vol. xi. p. 255. 

° «*Text-Book of Physiology,” 1889, 5th edition, part ii. p. 476. 


ABSORPTION OF PROTEIDS. 439 


Changes in albumose and peptone during absorption.» — Although 
there is no doubt that a considerable, if not the greater part of 
the proteid of the food is absorbed as albumose or peptone, these 
bodies are never found in appreciable amount in the blood.. Schmidt- 
Miilheim ? stated that the maximum amount in serum is 0°028 per cent.; 
but recent experiments by Neumeister® have given an altogether 
negative result, and, according to this observer, albumoses are not present 
at all in blood, even in traces. 

Injected directly into the blood, albumoses and peptone are treated 
by the organism as foreign bodies; they are not assimilable proteids, but 
are promptly excreted by the kidneys, unless injected in large quantities,* 
and in a short time practically all the peptone and albumose injected is 
found in the urine, while not a trace is to be found in the blood.’ 
That albumose and peptone are foreign substances in the blood stream, 
is shown not only by this rapid elimination, but by the fact that they 
possess, besides, marked toxic properties, and cause the death of the 
animal when injected in larger doses, producing an immense and rapid 
fall in arterial blood pressure; im addition, they so alter the nature 
of the blood that on drawing it from the vessels it no longer coagulates, 
or does so very slowly. These results, taken in conjunction with the 
fact that normal urine never contains albumoses, even in traces, prove 
that the albumoses and peptones absorbed from the alimentary canal 
never reach the general circulation as such, but are somewhere on their 
route converted into other substances which can harmlessly enter the 
circulation. Positive experiments on the subject not only confirm this 
indirect proof, but clearly indicate that the change takes place in the 
lining epithelial cells. 

Seat of the modification of albumose and peptone during absorption.— 
It might be supposed that the albumose and peptone disappeared as 
such in the liver; this is not, however, the case. Schmidt-Miilheim ® 
found that the portal vein during proteid digestion contained no greater a 
percentage of these bodies than the arterial blood, and Neumeister’ found 
that the portal vein, while absorption of peptone was going on, did not 
contain a trace of this material. Neumeister also circulated defibrinated 
blood, to which peptone had been added through a liver immediately 


1 In many of the papers referred to in this section, ‘‘ peptone” is used to signify what 
would to-day be called a mixture of albumose and peptone ; this has usually been trans- 
lated hy albumose and peptone, or by albumose. 

2 Arch. f. Anat. u. Physiol., Leipzig, 1880, S. 33. See also Hofmeister, Arch. f. exper. 
Path. u. Pharmakol., Leipzig, 1885, Bd. xix. S. 17. 

3 Zischr. f. Biol., Miinchen, 1888, Bd. xxiv. §. 277. Neumeister caught the blood 
from the carotid in ammonium oxalate to prevent clotting ; laked by shaking with ether ; 
removed ether ; saturated with ammonium sulphate; filtered ; reduced filtrate by evapor- 
ating to a small bulk, filtering from time to time from crops of crystals ; and tested in final 
filtrate for albumoses by the biuret test with negative results. Control experiments showed 
that even a trace of albumose added to the blood intentionally could be easily identified. 

4 When large amounts are injected, the fall in arterial blood pressure is so great that 
secretion of urine is arrested. Even in such a case the albumose does not remain in the 
blood, but passes into the lymph (Shore, Journ. Physiol., Cambridge and London, 1890, 
vol. xi. p. 549). 

° Ploz and Gyergyai, Arch. f. d. ges. Physiol., Bonn, 1875, Bd. x. S. 536; Hofmeister, 
Ztschr. f. physiol. ‘Chem. Strassburg, 1881, Bd. v. S. 131 ; Schmidt- Miilheim, Arch. eZ 
Anat. u. Physiol., Leipzig, 1880, S. 33; Fano, ibid.. 1881, s. 281 ; Shore, Journ. Physiol., 
Cambridge and London, 1890, vol. xi. p. 528. A similar effect follows subcutaneous 
injection (Hofmeister, Zoc. cit.). 

6 Arch. f. Anat. u. Physiol., Leipzig, 1880, S. 33. 

7 Sitzungsb. d. phys.-med. Gresellsch. zu Wiirzburg, 1889, S. 65; Ztschr. f. Biol., 
Miinchen, 1888, Bd. vi. S. 287. 


oa 
J 


440 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


after its removal from the body, and proved that the peptone remained 
unchanged. Also, when a small quantity of peptone or albumose was 
slowly injected into a mesenteric vein, this was not assimilated, but 
appeared afterwards in the urine, showing that it had not been altered 
by the liver. Shore? circulated peptone not only through the liver, but 
through the spleen also, by injecting into a splenic artery, and arrived at 
similar results; practically, all the peptone appeared again in the urine 
unchanged. 

These results show that the albumose and peptone do not even enter 
the portal circulation as such; the only remaining place where they can 
undergo modification is in the wall of the intestine itself, and the 
following experiments show that this is the seat of change. 

Ludwig and Salvioli? separated a loop of intestine in the dog with 
the attached portion of mesentery, and injected a gramme of albumose and 
peptone in 10 per cent. solution, ligaturing the piece of intestine at both 
ends. The piece of isolated intestine was maintained alive by circulating 
through it warm defibrinated blood diluted with normal saline, by means 
of a cannula inserted into that branch of the mesenteric artery which 
had supplied the loop (anastomosing arterial branches being excluded by 
ligatures), the blood, after circulating, flowing away by the corresponding 
branch of the mesenteric vein. After four hoursof perfusion in thismanner, 
the piece of intestine and the defibrinated blood having been all the time 
maintained at the body temperature, the remaining contents of the intes- 
tine and the circulating fluid were examined for albumose. The intestine 
contained about half a gramme of coagulable proteid, and only traces of 
albumose, while the defibrinated blood contained no albumose whatever. 
Therefore the albumose must have disappeared in the intestinal wall. 

Hofmeister * investigated the organs of dogs killed during proteid 
digestion as to their content of albumose, and found it present in the 
mucosa (only) of the stomach and intestine, as well as in small quantities 
in the blood, and in four out of ten cases in the spleen; in the other 
organs it was entirely absent. He also showed experimentally that this 
albumose underwent a rapid change. 


A fresh stomach was divided into two symmetrical halves, or a piece of 
small intestine longitudinally into two similar pieces. 

The surface of the mucous membrane was washed clean with saline, then 
one of the two pieces in each case was thrown immediately into boiling water, 
while the other was similarly treated after being first kept for some time in a 
moist chamber at 40° C. More peptone was always found in the first piece 
than in the second, and when the second piece had been kept for a sufficient 
time (1 to 2 hours) at body temperature, previous to placing in boiling water, it 
was found to contain no albumose whatever. In another experiment, while 
one piece was thrown, as before, immediately into boiling water, the second was 
thrown for some minutes into water at 60° C., and then kept as before at 40° 
C. for two hours ; the result now obtained was that both pieces contained an 
equal amount of albumose. Since most enzymes would not be affected by such 
a preliminary treatment, while living cells would be destroyed, this indicates 
that the cells of the mucosa do not owe their activity to contained enzymes. 


1 Journ. Physiol., Cambridge and London, 1890, vol. xi. p. 559; Verhandl. d. X. 
internat. med. Cong., Berlin, 1891, Bd. ii. Abth. 2, S. 31. 

2 Arch. f. Anat. u. Physiol., Leipzig, 1880, Supp. Band, S. 112. 

* Ztschr. f. physiol. Chem., Strassburg, 1882, Bd. vi. 8, 51; Arch. f. exper. Path. u, 
Pharmakol., Leipzig, 1885, Bd. xix, S. §, 


i 


ABSORPTION OF PROTEIDS. 44r 


Neumeister! states that albumoses and peptones dissolved in 
whipped blood can be changed by mere contact with pieces of living 
intestine, the rapidity of change being increased when a slow stream of 
air is driven through the mixture, so as to bring the pieces of intestine 
into rapid contact with different portions of the blood and albumose. 

Hofmeister? observed a considerable increase in the number of 
leucocytes in the intestinal wall during digestion of proteids, and argued 
from this that these took a considerable share in proteid absorption and 
in the conversion of albumoses and peptones in the adenoid tissue of 
the intestinal wall, and in the mesenteric lymphatics. There is little 
experimental ground for belief in such a theory. In the first place, 
proteid is not absorbed to any appreciable extent by the lymphatics; 
secondly, albumoses are not changed, as Hofmeister ? himself has shown, 
in the blood, which contains plenty of leucocytes; thirdly, Heidenhain + 
has shown that the amount of leucocytes in the wall of the intestine 
(and the amount of active mitosis in these) is too small to render them 
adequate for such a purpose. Finally, Shore® has shown that, after 
slow injection of a small amount of peptone (049 grms.} into a lym- 
phatie of the hind-limb in a dog, this can be detected again in the course 
of twenty minutes in the chyle flowing from a fistula of the thoracic 
duct, showing that it has traversed the lymphatic system unchanged. 

All these experiments go to prove that albumoses and peptones are 
modified during their passage through the epithelial cells by the action 
of living protoplasm. What substances are formed from them is not 
known by direct experiment, but it is highly probable that the process 
is one of conversion backwards into coagulable proteid. It is known 
that coagulable proteid can be artificially obtained from peptone and 
albumose,® and that albumose and some forms of peptone used as foods 
can replace coagulable proteid in maintaining nitrogenous equilibrium. 
It is difficult to see how such a result can be attained otherwise than by 
a formation of coagulable proteid from albumose and peptone. 

The percentage of any proteid foodstuff, which is absorbed from the 
alimentary canal, may be deduced fairly accurately from a comparison 
of the amount of nitrogen in the food with that of the urine and feces 
when such a food is taken into the system. 

Experiment shows that the various forms of proteid are utilised by 
the organism in widely varying degrees. It does not necessarily follow 
that a food of which the nitrogenous part is only partially absorbed is 
on that account to be despised as an adjunct to other classes of 
nitrogenous food ; vegetable proteid is absorbed much more imperfectly 
than that from animal sources; but vegetable food, amongst other 
things, is valuable for the consistency and bulk it gives to the food, 


1<*Tehrbuch der physiol. Chem.,” Jena, 1893, Th. 1, S. 251; Ztschr. f. Biol., 
Miinchen, 1890, Bd. xxvii. S. 324. 

2 Arch. f. exper. Path. u. Pharmakol., 1885, Bd. xix. S. 32; 1886, Bd. xx. S. 291; 
1887, Bd. xxii. S. 306. See also Pohl, ibid., 1888, Bd. xxv. S. 31; Heidenhain, Arch. /f. 
d. ges. Physiol., Bonn, 1888, Supp. Heft., Bd. xliii. S. 72. 

3 Hofmeister (Joc. cit., Bd. xix.) is of the opinion that the portion of ‘‘ peptone” which 
he believes enters the blood unchanged is converted in the tissue, ‘‘ peptone” being found 
during digestion in the arteries but not in the veins. The presence of any albumose or 
peptone, even in the arteries, is, according to more recent observers, however, very doubt- 
ful. 

= Loc. cit. 

5 Journ. Physiol., Cambridge and London, 1890, vol. xi. p. 553. 

6 See p. 400, 


442 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


and for the mechanical stimulation its presence gives to the intestinal 
movements. 

The small amount of vegetable proteid absorbed, compared with that 
of animal proteid, is in part due to the envelope of indigestible cellulose 
by which it is surrounded, in part to the shorter stay in the intestine 
due to its action in causing increased peristalsis, and in part to its own 
less digestible character. 

The percentage of various kinds of plant proteid absorbed also varies 
considerably ; thus the proteids of some leguminous plants and cereals are 
absorbed nearly as perfectly as those of animal origin, while in most 
others (potato, lentil) it is much less complete (22 to 48 per cent. less). 
The percentage of the nitrogen of meat or egg appearing again in 
the feces in man, only amounts to 2°5 to 28 per cent., that of milk to 
6 to 12 per cent. 

Considerable tracts of the alimentary canal can be removed or 
thrown out of action without causing the death of the animal or even 
causing serious impairment in absorption. 

The stomach was first removed by Czerny' in dogs; one animal 
was preserved alive after such an operation for five years ; in the course 
of two months after the operation it recovered to quite a normal con- 
dition, and ate, digested, and absorbed all kinds of food. It was finally 
killed for examination by Ludwig and Ogata, and the dissection 
showed that only a very small por tion of the cardiac end of the stomach 
remained. 

Ludwig and Ogata? further investigated the course of digestion and 
absorption. when gastric digestion is excluded, by another method. They 
made a fistula beyond the pylor us and inserted into the beginning of the 
duodenum a small thin rubber ball, attached to a rubber tube, by means 
of which it could be distended with water under pressure, so as to 
occlude the intestine from the stomach. In this way gastric juice could 
be prevented from entering the duodenum, and by feeding from the 
fistula the effect of intestinal digestion alone be studied. The food was 
usually completely digested and absorbed, and the faces presented a 
normal appearance. Raw meat was digested much more efficiently than 
boiled, connective tissue was not so completely digested as in normal 
dogs, but nevertheless two injections of meat per diem sufficed to keep 
the animal in equilibrium. 

The stomach has also recently been removed in dogs by F. de Fillipi,? 
who found no disturbance in metabolism and no increase in intestinal 
putrefaction in spite of the absence of hydrochloric acid. 

The same experimenter also removed in a bitch 1:9 metres of the 
small intestine (almost the entire length), and found no metabolic 
disturbance, except that the absorption of fat was diminished ; the animal 
lived, and afterwards brought up a litter of pups im this condition. 
The author suggests that the large intestine here vicariously took on the 
absorptive functions of the small intestine. 

Complete or partial extirpation of the pancreas, or ligature of its 
duct, causes more or less disturbance of proteid digestion and absorption, 
but not so much as might be expected, in view of the most important 
proteolytic function of the secretion of this gland. 


1 « Beitrage z. operativen Chirurgie,” Stuttgart, 1878, S. 141. 
2 Arch. f. Anat. u. Physiol., Leipzig, 1883, S. 89. 
3 Deutsche med. Wehnschr. , Leipzig, 1894, No. 40, S. 780 


DIGESTION AND ABSORPTION OF FATS. 443 


Minkowski and Abelmann! found, after complete removal of the 
gland in dogs, that on an average 44 per cent. of proteid was absorbed ; 
after par tial removal, 54 per cent. The amount of absorption was much 
increased on giving raw pancreas with the food. Sandmeyer? obtained 
similar results. On removal of all but one-fifth to one-fourth of the eland 
(the portion remaining behind not being in communication with the 
intestine), 60 to 70 per cent. of proteid was still absorbed, and, on adding 
a supply of finely-minced pancreas to the food, the absorption of proteid 
became almost normal. 


DIGESTION AND ABSORPTION OF FATS. 


The pancreatic juice is the only digestive secretion which contains an 
enzyme possessing a chemical action on the neutral fats. This action 
consists in splitting the fats into fatty acids and glycerin,* and may 
be demonstrated in one of the following ways :— 

1. A neutral fat is first obtained, eg., by thoroughly shaking olive 
oil with sodium carbonate solution and ether, pipetting off the ethereal 
layer, filtering if necessary, and finally allowing the ether to evaporate, 
when a neutral fat is left behind, "his is mixed either with fresh 
pancreatic juice, or an extract of the fresh gland prepared as already 
described, and the mixture, after being coloured blue by the addition 
of litmus, is placed in a bath at 37° to 40° C. The alkaline reaction is 
seen gradually to change into an acid one. 

2. Instead of adding litmus, after the mixture of neutral oil and 
pancreatic juice, or extr act, has digested for some time (half to two hours), 
sodium carbonate solution is added (which converts the free fatty acids 
formed into soaps), and the unattacked fat is removed by repeated 
extraction with ether. The residue is next treated with dilute 
sulphuric acid, setting free again the fatty acids, which are extracted 
with fresh ether, and recovered after its removal by evaporation. 

The formation of free fatty acid may be also qualitatively shown, 
by removing water from the fresh, finely-divided gland, with 90 per cent. 
aleohol, drying it with filter paper, and then covering it with a neutral 
ethereal solution of butter, obtaimed by shaking up milk or cream with 
ether and a solution of caustic soda. When this material is kept for a 
short time at 57° to 40° C., a distinct odour of butyric acid appears ; and if 
the mixture has been previously rendered blue by litmus, this turns red. 

Form in which fats are absorbed from the intestine.—There has 


been much discussion as to the extent to which the decomposition 


of the fats by the pancreatic enzyme, as above described, takes place 
in the intestine; and also as to the subsequent fate in the intestine 
of the fatty acids formed therein. According to the views held on 


1 “* Ueber die Ausnutzung der Nahrungsstoffe nach Pancreasextirpation,” Inaug. Diss., 
Dorpat, 1890 ; Jahresb. tv. d. Fortschr. d. Thier-Chem., Wiesbaden, 1890, Bd. xx. S. 45. 

*Ztschr. f. Biol., Miinchen, 1895, Bd. xxxi. S. 35 

3 Fats are said to undergo a certain amount of decomposition into fatty acids in the 
stomach (Marcet, Proc. Roy. Soc. London, 1858, vol. ix. p. 806; Cash, Arch. f. Anat. u. 
Physiol., Leipzig, 1880, 8. 323); the cause of this decomposition is unknow n, but it is 
probably bacterial during ¢ the first sta ge of gastric digestion. 

4 Bernard, Compt. rend. Acad. d. sc., Paris, tome xxviil. ; Arch. gén. de méd., Paris, 
1849 ; “ Mémoire sur le pancréas,” Paris, 1856 ; “‘Lecons de physiologie expérimentale,” 
tome ii. p. 256. For the chemical equations representing such a decomposition, see 
Chemistry of the Fats, p. 19. 


444 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


these subjects by different. experimenters, various theories have been 
propounded as to the form in which fats leave the intestine. These 
theories may be divided into two classes—(a@) Those in which it is held 
that the fats are absorbed in particulate form, as emulsified fats or 
fatty acids; () those in which it is held that the fats are absorbed in 
solution as fatty acids or as soaps. 

EHmulsification—All fat or oil which has not been specially 
neutralised contains a slight amount of free fatty acid. On long 
standing in contact with air, the amount of this fatty acid is increased, 
probably by bacterial action; when this proceeds beyond a certain 
limit, the fat is said to become rancid. 

If such a rancid oil, or fat melted by gently warming, be briskly 
shaken up with a solution of an alkaline carbonate (e.g. a 0°25 per cent. 
solution of sodium carbonate), it becomes suspended permanently in the 
alkaline solution in the form of very minute particles or globules, 
and so forms what is known as a permanent emulsion. But if the 
rancid oil be previously carefully neutralised (eg. by mechanically 
shaking for some hours with a saturated solution of barium hydrate 
at 95° C., and then pipetting off), no amount of shaking with a solution 
of an alkaline carbonate afterwards will cause it to yield a permanent 
emulsion; the fluid on standing will quickly settle into two distinct 
layers. Neither can a lasting emulsion be obtained by shaking up a 
rancid oil or fat with distilled or acid water; some free fatty acid and 
some alkali must be simultaneously present. In other words, the 
necessary conditions for the formation of a soap must be satisfied.? 

Emulsifying action of alkaline salts and bile——Attention was first 
drawn to the action of alkaline salts in promoting emulsion by Marcet 
in 1857; this author investigated the effect of both disodic phosphate 
and of bile on fatty acids and on neutral fats; his results have not 
obtained, even in English text-books, the attention they deserve, and 
seem in part to have become forgotten. The results with bile and 
fatty acids have an important bearing on more recent researches, to be 
subsequently described, and for this reason are here quoted at length. 


Disodic phosphate, ‘‘ when mixed with pure stearic and margaric acids 
prepared from sheep’s fat, and heated, produced a perfect emulsion, resembling 
milk ; on cooling, a substance solidified, consisting of fatty acids with more or 
less soda, soap, and a small quantity of phosphate of soda; therefore the 
formation of the emulsion had been attended with that of a small proportion 
of soap. When neutral fats were heated, suspended in a solution of phosphate 
of soda, no emulsion occurred ; the fats fused, and, on cooling, solidified under 
the form of a hard cake; the warm mixture, although strongly shaken, was 
not converted into an emulsion, but the minutely divided globules of fat rose 
to the surface, uniting with each other, and solidified on cooling; the fluid 
remained perfectly clear. 

“The next subject for inquiry was to determine whether bile exerts 
a similar action on fatty acids and neutral fats. On heating and agitating 
gently a mixture of fresh sheep’s bile and fatty acid (margaric, stearic, and 


! Rachford, Journ. Physiol., Cambridge and London, 1891, vol. xii. p. 73. 

? Only formation of ‘‘ artificial emulsions,” if the expression may be used, from rancid 
oils is referred to here ; it will be seen later that a pancreatic emulsion can be formed and 
persist in presence of an acid reaction due to fatty acids. 

5 Compt. rend. Soc. de biol., Paris, 1857, p. 191: Proc. Roy. Soc. London, 1858, vol. ix. 
p. 306; Med. Times and Gaz., London, 1858, N. S., vol. xvii. p. 209. The extracts are 
taken from the last quoted Journal, 


DIGESTION AND ABSORPTION OF FATS. 445 


oleic acids), prepared from sheep's fat, as soon as the latter had begun fusing tt 
disappeared, and finally the whole of the fatty acid was dissolved ; on standing, 
however, it was observed that a very few extremely minute globules of fat rose to 
the surface. As soon as the mixture had been allowed to become colder than the 
temperature of fusion of the fatty acids, it assumed a turbid appearance 
throughout, which gradually increased, the fluid becoming white and milky, 
slightly coloured by the bile; finally, if the fat present was in sufficient 
proportion, the whole mass was converted into a semifluid paste, possessed of 
a light green colour, and adhering so strongly to the sides of the vessel that it 
could be turned upside down without letting out its contents. 

“On diluting this remarkable emulsion with water, its consistency only 
was altered, becoming thinner, but no decomposition occurred; on heating 
the diluted mass, the emulsion was dissolved ; it disappeared, but no globules 
of fat could be seen floating on the surface beyond the few minute specks 
previously mentioned. Besides this physical action of bile on fatty acids, the 
phenomenon was accompanied by a chemical decomposition; for the bile, 
which was neutral or slightly alkaline before the experiment, had become 
strongly acid after being treated with the fatty acid. 

“An experiment was now instituted to determine whether a similar 
phenomenon takes place when bile and zewtral fats are mixed together. 
Indeed, it was hitherto generally admitted that bile had no action on neutral 
fats. The results of my observations confirm this view, for in no case could I 
sueceed in obtaining an emulsion and chemical decomposition, by heating bile 
with pure sheep’s fat or with oil, having a neutral reaction; on agitating the 
hot mixture the globules of fat were broken up, but on standing they rose to 
the surface, the bile being unaltered in its appearance and reaction. Conse- 
quently, bile exerts no action on neutral fats.” 


Since these experiments of Marcet, many observers have busied 
themselves with the nature and mode of formation of emulsions." 

Briicke found that the presence of a certain amount of free fatty acid 
was sufficient to emulsify the remaining neutral fat, and stated that the 
provision of a sufficient amount of free fatty acid to emulsify the rest 
was probably the chief function of the fat-splitting property of the pan- 
creatic juice. He obtained emulsion of fats containing fatty acids with 
diluted egg albumin, with bile, and especially with solutions of sodium 
carbonate and of borax. Gad discovered spontaneous emulsion, and 
earried out exact experiments on the most favourable conditions for the 
formation of emulsions. A spontaneous emulsion means the formation 
of a permanent emulsion without any mechanical assistance by shaking ; 
such as occurs when a drop of oil containing a sufficient percentage of 
free fatty acid (5-7 per cent.) is placed on an alkaline solution of suit- 

able strength (4 per cent. sodium carbonate). 

The following are the main conditions which influence the formation 
of spontaneous emulsions, according to Gad :— 

1. The power of different fats to form emulsions by contact with the 
same fluid depends (a) on the amount of free fatty acid in the fat, (>) on 
the solubility of the soaps formed from these fatty acids, (¢) on the 
viscosity of the fat. 

2. The power of the same fat to form emulsions in contact with 


1 Kiihne, ‘“‘ Physiol. Chem.,” 1866, S. 129 ; Briicke, Sitzwngsb. d. k. Akad. d. Wissensch., 
Wien, 1870, Bd. ee Abth. 2, ‘8. 362; J. Steiner, Arch. f. Anat. u. Physiol., Leipzig, 1874, 
Ss. 286 ; J. Gad, ibid., 1878, S. 181; G. Quincke, Arch. f. d. ges. Physiol., Bonn, 1879, Bd. 
SERGSE 129 ; v. Frey, Arch. fe Anat. Ww. Physiol., Leipzig, 1881, S. 382 ; ‘Rachford, Journ, 
Physiol., Cambridge and London, 1891, vol. xii. p. 72. 


446 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


different fluids depends (a) on the degree of alkalinity of the fluid, (0) on 
their chemical composition, in so far as this influences the solubility of 
the soaps formed. 

3. The maximum of quantity and quality of emulsion formed coin- 
cides with those conditions under which no formation of a membrane 
can be demonstrated. 


There has been much discussion as to the factors at work in the formation 
and conservation of emulsions. JBriicke was of the opinion that it was the 
dissolved soap which conferred on the solution the power of holding the 
globules apart, after they had been mechanically formed in it. Gad supposed 
that the breaking up of the globules into smaller ones was due to a want of 
correspondence of the rate of solution and diffusion of the soap formed into 
the outer solution with the rate of diffusion of fatty acids towards the sur- 
face of the globule. In case fatty acid diffuses from the inner part of the fat 
globule towards the common surface of oil globule and solution more quickly 
than it can be dissolved by the solution, a film or membrane of soap will form 
around the globule. This film will not form at all parts of the globule equally, 
and this will give rise to amceba-like movements (due to differences in surface 
tension).”_ Gad also supposes that the ultimate microscopic globules are sur- 
rounded by soap films which keep them from coalescing. 

Quincke attributes the formation of the emulsion to the differences in sur- 
face tension produced by the formation of a soap solution round the globule ; 
and he also assumes the existence of films of soap (solid or in solution) around 
the ultimate oil globules in the emulsion, which have the property of keeping 
the globules from coalescing. 

There is no doubt that soap formation is an accompaniment to the forma- 
tion of an emulsion of rancid oil in an alkaline solution, and it is easy to see 
how the formation of such a soap film, at accidentally varying rapidity, at 
different points on the surface of a clobule of oil, will cause variations in 
surface tension at these points, and so cause the oil globule following the soap 
film which covers it, to be drawn out into various shapes and split up. Such 
surface tension phenomena may be observed when two liquids which mix, 
such as alcohol and water, are brought together. More mixing takes place at 
one point than another ; as a consequence, the mutual surface tension is less at 
one point than another, and those rapid, streaming movements are produced 
which may always be observed when alcohol and water are mixed. Similarly, 
when a small piece of a substance like camphor is placed on water, rapid 
shooting movements take place, due to an accidentally unequal solution of the 
substance at different points in the circumference, and consequently varying 
surface tension, as a result of which the piece of camphor is rapidly moved 
about from place to place. In an exactly similar manner a globule of rancid 
oil will be pulled about, altered in shape, and broken up in an alkaline solu- 
tion, from accidental variations in the strength of soap solution at different 
points on its surface, causing variations in surface tension and corresponding 
movements. 

It is much more difficult to see how any permanent film of insoluble soap 
can be formed round the ultimate globules, or even a film of soap solution of 
different concentration from the rest of the menstruum in which the globules 
float. From Gad’s conclusions, it should be observed that in the cases where 
emulsion takes place best and most quickly, no such soap film can be observed, 
so that this soap film cannot be experimentally demonstrated ; it is merely a 
theoretical thing, devised from the supposed necessity of having something to 
keep the globules from coalescing. A proteid membrane surrounding the fat 
globules in milk was supposed to have a similar office, but microscopically or 


1 Vide infra. * The words in parenthesis are added. 


DIGESTION AND ABSORPTION OF FATS. 447 


otherwise no such membrane can be demonstrated, and its existence is very 
doubtful.! 

A cloud is an emulsion, an emulsion of water particles in air, and no one 
has ever supposed that the water particles are surrounded by membranes which 
keep them apart. The prevention of coalescence is the result of the action of 
several factors, of which our knowledge is not yet perfect. 1. One such 
factor is the magnitude of the suspended drops ; the bigger the drops the more 
rapidly they will come together, and fall (or rise) out of solution.2 The more 
mechanical agitation an emulsion is given, the longer it will persist under 
otherwise unfavourable circumstances. 2. Another factor is the viscosity of 
the menstruum; the greater this is the more slowly will the finely-divided 
globules be able to move through the fluid, under the influence of differences 
in specific gravity or mutual attraction, so as to pass out of solution or 
coalesce. 3. Another factor is the comparative specific gravities of the fat 
and menstruum. 4. Still another is the mutual surface tension between 
globule and menstruum; the greater this is, the greater will be the tend- 
ency to diminution of surface, and hence to coalescence. On the other 
hand, if the mutual surface tension were zero, the two fluids would mix in all 
proportions. 

It has been objected, by those who believe in the existence of a film around 
the fat globules, to the contention that the altered nature of the menstruum is 
sufficient to account for the permanency of the emulsions obtained with fats 
and alkaline solutions, that a permanent emulsion cannot be obtained by 
shaking up neutral fat with a soap solution. But the conditions in the two 
cases are essentially different. Neutral fats and fatty acids mix together in a 
rancid fat or oil in all proportions. When such a mixture is submitted to the 
action of alkali, the soap formation takes place where the fatty acids are, that 
is, intimately mixed with the neutral fat. So that soap is formed everywhere 
at the surface of the mass, and, dissolving, carries away (in the surface tension 
diffusion streams above described) the intimately admixed fat from the main 
mass in a very finely subdivided condition. If the proper conditions exist in 
the solution, these minute fat particles will not coalesce again. Such a result 
is brought about by the viscosity and reduction in surface tension which the 
solution acquires by means of the dissolved soap. On the other hand, when 
neutral fat is shaken up with soap solution, no such disintegrating agency 
comes into action, and the only thing to replace it is the mechanical subdivision 
due to shaking. As v. Frey points out, the smaller the diameter of the fat 
clobules, the greater is the mechanical force necessary to subdivide them ; and 
it is probable that by no amount of agitation can so fine a subdivision be 
reached as is naturally attained by the formation of the soap amongst the fat. 
By very prolonged and vigorous agitation, v. Frey has obtained ‘“‘ mechanical 
emulsions” of very considerable stability, even with neutral fats and water. 
The very fine subdivision of the fat, and the increased viscosity of the men- 
struum occasioned by the dissolved soap, are hence quite sufficient to explain 
the permanency of emulsions of rancid oils and fats in alkaline solution. 


Formation of emulsions in the intestine—The formation of an 
emulsion of fats in the intestine was already known to Eberle*® in 1834, 
but was first brought into prominence by the classic researches of 
Claude Bernard. Bernard was unacquainted with our modern theories 
of the formation of emulsion, and did not associate this process with 


1 See v. Frey, Arch. f. Anat. u. Physiol., Leipzig, 1881, 8. 382 ; Soxhlet, Landwirthsch. 
Versuchsstat., 1876, Bd. xix. 

? See v. Frey, Zoc. cit. 3 «Physiologie d. Verdauung,” Wiirzburg, 1834. 

+ Compt. rend. Acad. d. sc., Paris, 1849, tome xxviii. p. 249; Arch. gen. de méd., Paris, 
1849, Sér. 4, tome xix. p. 60; ‘‘ Mémoire sur le pancréas,” Paris, 1856. 


448 CHEMISTRY OF FHE, DIGESTIVE PROCESSES. 


the production of fatty acid by pancreatic juice, although he was the 
discoverer of this saponifying action. He states that, when neutral oil 
is shaken up with pancreatic juice, an instantaneous emulsion takes 
place; and, secondly, when neutral oil is submitted to the prolonged 
action of pancreatic juice, fatty acids are developed. Bernard con- 
sidered the formation of emulsion in the intestine as a more important 
process than saponification, due to a ferment action, and speaks of a 
“ferment emulsif.” It is now certainly known that fatty acids are 
always formed in the intestine after the ingestion of fat, but an emulsive 
ferment is no longer believed in. The rapidity of fresh pancreatic juice 
in forming fatty acid is remarkable; thus Rachford, in very favour- 
able cases, found that a sufficient amount of fatty acid to form a spon- 
taneous emulsion (5°5 per cent.) is formed in presence of bile and 
hydrochloric acid at room temperature in two minutes. This very 
rapid action explains the error into which Bernard fell? 


Pancreatic juice obtained from a permanent fistula has less emulsive 
power than that from a temporary fistula; it is also poorer in proteid, and, 
according to Kiihne,’® the emulsive power does not depend upon the alkali, 
for faintly acid juice is capable of producing emulsion. Minkowski is of the 
opinion that it is chiefly to the proteid that ‘emulsion is due, basing his 
opinion on the observation, made by Abelmann* in his laboratory, that after 
excision of the pancreas no fat except that of milk is absorbed ; unless minced 
pancreatic tissue be taken with the food, when other fats are also absorbed. 
These observations have been confirmed by Sandmeyer.® 

Some observers® hold that emulsification does not occur at all inside the 
intestine, and others’ state that a considerable amount of emulsification takes 
place, but that the granules of fat in the emulsion are not nearly so small as 
those found in the chyle. 

Cash*® found, in four experiments on dogs, that there was no emulsion 
in the intestine during active fat absorption. Moore and Rockwood,® in six 
out of sixteen experiments, obtained a similar result, but in the other ten 
experiments found emulsions in the intestine, containing fat globules of 
various dimensions, some of considerable size, but many exceedingly minute. 
These results indicate that in the dog at least, fats can be broken up and 
absorbed without undergoing previous emulsification. Still it should be 
borne in mind that these two different conditions of the intestine in the 
dog during fat absorption may be phases of the same process. The contents 
of the stomach are not discharged continuously into the duodenum, but from 
time to time the pyloric sphincter is relaxed, and a portion of the contents 
of the stomach ejected. It may well be that the condition of no emulsion is 


1 Journ. Physiol., Cambridge and London, 1891, vol. xii. p. 92. 

* The statement that the fat-splitting action of the pancreatic enzyme is very slow, and 
hence that probably only a small percentage of fat is so decomposed in the intestine 
(see Bunge, ‘‘ Lehrbuch,” Aufl. 3, S. 175), undoubtedly arises from most observers using 
not pancreatic juice but pancreatic extracts, in which the easily decomposable fat-splitting 
enzyme was only present in traces. Rachford’s results with pancreatic juice clearly indicate 
that the pancreatic secretion is capable within the time of digestion of a fatty meal of 
decomposing all the fat into fatty acids and glycerin. 

3 “Tehrbuch d. physiol. Chem.,” 1868, S. 122. 

4TInaug. Diss., Dorpat, 1890. 

> Ztschr. f. Biol., Miinchen, 1895, Bd. xxxi. S. 40. 

6 Cash, Arch. f. Anat. u. Physiol, Leipzig, 1880, S. 323; Altmann and Krehl, 7bid., 
1889, Anat. Abth., Supp. Bd. S. 86; 1890, Anat. Abth., S. 97. 

7 Heidenhain, Arch. f. d. ges. Physiol., Bonn, 1888, Supp. Heft, Bd. xliii. S. 88, 
Other recent observers who describe an emulsion in the intestine are, Lebedeff, Arch. f. 
Anat. u. Physiol., Leipzig, 1883, S. 504; Lewin, Arch. f. d. ges. Physiol., Bonn, 1896, Bd. 
Ixiii. S. 180. 

Su GGniCete ® Journ. Physiol., Cambridge and London, 1897, vol. xxi. p. 74. 


EMULSION THEORIES OF FAT ABSORPTION. 449 


that existing immediately after such a discharge from the stomach, while the 
emulsion condition is a later stage. 

In whatever form fats may be absorbed from-the intestine, it is certain 
that previous emulsification must greatly assist the digestive fluids, by 
exposing an infinitely greater surface to their action. It is also certain that 
in a great many cases, if not in all, previous emulsification does take 
place. 


Emulsion theories of fat absorption.—It was for a long time a 
popular theory that only a small fraction of fat is split up in the intes- 
tine into fatty acid and glycerin; and that by means of the small 
amount of acid so formed, aided by that present in the fat as it leaves 
the stomach, the remainder of the fat is converted into a fine emul- 
sion which passes as such into the villi, and reaches the central lacteal+ 
Such a statement may be found in most text-books, but the progress of 
recent work has had a tendency to cast grave doubts on its truth, and 
to show that, at least as a general statement, it is erroneous. The theory 
does not rest on any direct observation of the amount of fat which 
leaves the intestine as emulsified fat, compared with that which leaves 
it in other forms, such as soap, glycerin, and emulsified fatty acids, 
—such a direct observation, in the present state of our knowledge, is 
impossible,—but on indirect evidence, which is briefly as follows :— 

1. The presence of a very small percentage of fatty acid is all that 
is necessary in presence of an alkaline solution to perfectly emulsify 
neutral fat. 

2. This small amount of free fatty acid can readily be furnished by 
the action of the pancreatic enzyme even on neutral fats, and to aid this 
action all fats contain already some fatty acid mixed with them. The 
alkaline juices poured into the intestine are capable of supplying the 
alkali necessary for emulsification. 

3. When an animal is killed during active fat digestion, the lacteals 
invariably contain a white milky emulsion, consisting mainly of neutral 
fats with a small percentage of alkaline soaps. 

Therefore the most natural conclusion is that a fine emulsion is 
formed in the intestine which passes in some manner into the lacteal. 
The greater part of the fat is only physically, not chemically, 
altered in digestion, and passes through the whole process as a neutral 
fat. 

The weak point in the emulsion theory of absorption always was, 
how the fat globules got into the interior of the villus and made their 
way to the lacteal. Although the fat granules in an emulsion are of 
microscopic dimensions, they are still large compared to the dissolved 
molecules of serum or egg albumin which are unable to pass into or out 
of the intestine through the epithelial cells. If fat granules pass into 
the epithelial cells at all, it must therefore be by means of a 
special kind of absorption in bulk by these cells, and not by a process 
even of selective diffusion from solution. Such an absorption by bulk is 
easily carried out by a cell of which the protoplasm is capable of free 
contraction, such as the amceba, or leucocyte, but it is difficult to conceive 
how it can take place with a fixed cell, such as those which line the 
intestine. Impressed, perhaps, with the necessity of some such proto- 
plasmic movement, some observers have looked earnestly for proto- 

1 This theory was first stated by Briicke, Sifzwngsb. d. k. Akad. d. Wissensch., Wien, 
1870, Bd. Ixi. Abth. 2, S. 362. 

VOL. I.—29 


450 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


plasmic processes from the epithelial cells, and one or two ! fancied they 
had discovered such appearances, but their observations have not been 
confirmed, and are undoubtedly erroneous. If the epithelial cells of the 
intestine possessed the power of absorbing in bulk fat granules, there 
is no obvious reason why other food particles, such as granules of 
starch or proteid, should not be similarly absorbed, but no such 
absorption has ever been observed, nor are they capable of absorbing 
finely subdivided granules of coloured matter, such as carmine. 

The mucous membrane of the intestine contaims an immense 
number of lymph corpuscles.2, These are found not only in the lymph- 
oid nodules, which occur so abundantly as solitary glands and Peyer’s 
patches, but in the intestinal villi, even between the epithelial cells, where 
they may approach quite close to the free surface, and abundantly in the 
adenoid tissue underlying them. Now,such lymph corpuscles are capable 
of enveloping and so absorbing fat granules, and have been credited with 
an important function in the removal of fat from the imtestine by so 
doing. It was stated by Zawarykin ® that when fat absorption is going 
on, fat granules are to be found only in these lymphoid cells and not in 
the cells of the columnar epithelium. This statement is undoubtedly 
erroneous, for it is easy, from an animal killed after a meal rich in fats, 
to obtain sections showing the columnar cells filled with fat globules. 

“During active fat absorption, especially if the amount of fat in the 
chyme is relatively large, the columnar epithelial cells become filled 
with globules of fatty matter. These globules are of variable size, and 
may occur in all parts of the cell, but they are generally largest in the 
part between the nucleus and the thickened border, and are often quite 
small near the attached end of the cell.” 4 

It is evident, then, that the greater part of the fat, if not the whole 
of it, must be absorbed by the epithelial cells from the intestine. It 
is also very improbable that these cells take up the fat in the form of 
an emulsion. As has already been stated, the structure of the cell is 
unsuitable for such a function, and, in addition, fat granules have never 
been observed in the broad striated border. This almost amounts to a 
demonstration that the fat passes through the border of the cell in some 
soluble form, and is afterwards thrown down in a particulate form, as the 
result of a process of cell metabolism. 

Emulsion theories of fat absorption are therefore being gradually 
replaced by theories of absorption in solution. These theories must 
next be discussed, but before doing so reference may be made to another 
emulsion theory of fat absorption introduced by Munk. 

Theory of I. Munk.—Munk® showed that fatty acids can be 
emulsified under exactly the same conditions as rancid fats, and further 
that these fatty acids are capable of absorption, and can completely take 
the place in the animal economy of neutral fats, being in great measure 

ly. Thanhoffer, Arch. f. d. ges. Physiol., Bonn, 1874, Bd. viii. S. 391; Fortunatow, 
tbid., 1877, Bd. xiv. S. 285. 

? These wandering cells ( Wanderzellen) were first described as occurring in the epithelium 
py Eberth (Wirzb. med. Ztschr., 1864, S. 23); Arnstein (Virchow’s Archiv, 1867, Bd. 
xxxix. 8. 537) first mentioned the presence of fat granules in them. 

° Arch. f. d. ges. Physiol., Bonn. 1883, Bd. xxxi. S. 281. 

4 Schafer, Internat. Monatschr. 7. Anat. u. Histol., Leipzig, 1885, Bd. ii. S. 6. 

° Verhandl. d. Berl. med. Gesellsch., March 1879 ; Arch. f. Anat. u. Physiol., Leipzig, 
1879, S. 371; Virchow’s Archiv, 1880, Bd. Ixxx. S. 10; ibid., 1884, Bd. xcv. S. 409; Zéschr. 


J. physiol. Chem., Strassburg, 1885, Bd. ix. S. 568; Arch. f. Anat. u. Physiol., Leipzig, 
1890, Supp. Bd., S. 138. See also v. Walther, tbid., 1890, S. 329. 


SOLUTION THEORIES OF FAT ABSORPTION. 451 


converted into fats somewhere on their way from the intestine to the 
thoracic duct. He is hence of the opinion that in the normal course of 
digestion a considerable but indeterminate amount of fat may be 
absorbed in the form of emulsified fatty acids. 

Munk’s experimental results as to the absorption and synthesis 
during the process of absorption of the fatty acids, are of the highest 
importance ; but it in no wise follows from them that the fatty acids 
are absorbed in the form of an emulsion. Such a theory is subject to 
the same objections as have above been urged against the older theory 
of absorption as emulsified fats. The fatty acids are probably taken 
up from the intestine by the epithelial cells in some soluble form, and 
synthesised to neutral fats in these cells. 

Solution theories of fat absorption.—TZheory of absorption as 
soaps.—One of the most important theories of fat absorption in soluble 
form is, that the neutral fats are split up by the action of the pancreatic 
enzyme into fatty acids and glycerin, that the fatty acids unite with a 
part of the alkali of the intestinal secretions to form alkaline soaps 
which are soluble in water, and that the alkaline soaps and glycerin 
are absorbed in solution by the epithelial cells, and there synthesised 
back to neutral fats. This theory is supported by a good deal of 
experimental evidence. Radziejewski! showed that alkaline soaps were 
absorbed; Perewoznikoff? that a mixture of alkaline soap and glycerin 
was absorbed and synthesised to neutral fat. The lacteals had the usual 
milky appearance seen after a fatty meal; microscopic preparations, 
stained with osmiec acid and with alkanna, showed in the tissue of the 
villi, and in the epithelial cells, fat globules of varying size. Will,? work- 
ing under Griinhagen’s direction, confirmed these results by histological 
observations on the frog; further, he showed that the presence of 
glycerin was unnecessary. Will made two kinds of experiments. In 

one he fed the frogs, which had previously been deprived of food, 
with the materials to be tested; in the other, he injected the materials 
into the living but cut out intestine, and then examined teased speci- 
mens stained with osmic acid. In both series the same results were 
obtained, on feeding with a mixture of pure palmitic acid and glycerin, 
or of potassium palmitate and glycerin; at the end of twenty-four 
hours an examination of the villi showed a formation of fat, by the 
presence everywhere of large distinct fat globules. Injection of palmitic 
acid alone into the intestine also led to the appearance of fat globules 
in the epithelium,* but these were not nearly so numerous as in the 
cases In which the palmitic acid was mixed with glycerin. As 
Salkowski and Munk had shown that fatty acids can be emulsified 
under certain conditions,> Will proceeds to show that this could not be 
the case in his experiments, and that the fat globules blackening with 
osmic acid in the epithelial cells are not free fatty acid. The free fatty 
acids only become emulsified when melted, and as pure palmitic acid 
1 Virchow’s Archiv, 1868, Bd. xliii. S. 271 ; 1872, Bd. lvi. S. 211. 
2 Centralbl. f. d. med. Wissensch., Berlin, 1876, S. 851. 


° Arch. f. d. ges. Physiol., Bonn, 1879, Bd. xx. S. 255. See also v. Krehl, Arch. f. 
Anat. wu. Physiol., Leipzig, 1890, Anat. Abth., S. 97. 

+In thus showing the formation of fat from fatty acid alone, Will anticipated I. Munk, 
but to Munk belongs the merit of clearly showing from the chemical standpoint that the 
organism, probably the epithelial cells, can furnish the glycerin radicle for the synthesis 
of neutral fats from the fatty acids. 

> Sitzungsb. d. Berl. physiol. Gesellsch., March 1879 ; Virchow’s Archiv, 1880, Bd. lxxx. 
This was a re-discovery of a fact known to Marcet many years previously, see p. 444, 


452 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


only melts at 62° C., such a thing could not occur in the frog’s intestine. 
Moreover, a microscopic examination of the intestinal contents at the 
end of an experiment showed only amorphous masses of fatty acid and no 
emulsified globules. Will concludes that the fatty acid must be absorbed 
as a soap and not as an emulsion. 

That the mucous membrane of the small intestine is capable of 
taking part in such a synthetical process, is shown by experiments of 
Ewald,’ who dried the mucous membrane of a dog’s intestine, which had 
been killed in a condition of hunger, at a low temperature after the 
method introduced by Brown and Heron, and showed that this was 
capable of inducing the formation of neutral fat, from a mixture in 
proper proportions of soap and glycerin. 

This experiment shows that, provided glycerin and soap are formed 
in the intestine, there is an agency provided for synthesising them 
back into neutral fats. Let us next consider what the probabilities are 
that such a complete decomposition, into fatty acids and g¢lycerin 
followed by solution of the fatty acids as alkaline soaps, takes place in 
the intestine. 

The idea that only a small fraction of the fats is decomposed in 
the alimentary canal into fatty acids and glycerin, has arisen from 
repetition of the emulsion theory only, and not from any experimental 
observation of lack of intensity of action of the fat-splitting ferment. 
Hoppe-Seyler® found that most of the fatty matter in both small and 
large intestine was composed of stearic and palmitic acids accompanied 
by very little neutral fat, and concludes that the decomposition into the 
fatty acids and glycerin is much greater than is usually supposed. 
Rachford‘ states that pancreatic juice must act very rapidly on fats, 
under the favourable conditions found in the duodenum, and is capable, 
unless checked or retarded in some manner, of splitting all the fats of 
the food into fatty acids and glycerin in the time required for intestinal 
digestion. 

It may be concluded, then, that there is sufficient fat-splitting power 
provided in the intestine for the complete conversion of the fats into 
fatty acids; and it has been already pointed out that, on feeding with 
fatty acids or with soaps, these are absorbed, and converted into fats in 
the process. It only remains to consider, in connection with the soap 
theory, whether, in the natural process of fat digestion and absorption, 
it is probable that the fatty acids so set free combine with alkalies to 
form soaps, or whether they are absorbed in some other soluble form. 

It has been objected to the theory of absorption in the form of 
soaps, that the reaction of the small intestine in the dog during fat 
absorption is not alkaline, but acid; that soaps cannot persist in 
presence of an acid reaction, and hence that fats cannot be absorbed 
as soaps. 


Cash° investigated the reaction of the intestine in three experiments on 


dogs, in which the animals were fed on a mixture of starch and fat, and in 


three similar experiments in which the animals were fed on fat alone. He 


1 Arch. f. Anat. u. Physiol., Leipzig, 1883, Supp. Bd., ‘‘ Festschrift f. du Bois-Rey- 
mond,” S. 302, Vorlaufige Mittheilung, 

2 Proc, Roy. Soc. London, 1880, p. 393. 

3 Virchows Archiv, 1863, Bd. xxvi. §. 534, Anmerkung. 

4 Journ. Physiol., Cambridge and London, 1891, vol. xii. p. 92. 

> Arch. f. Anat. u. Physiol. Leipzig, 1880, S. 323. 


_SOLUTION THEORIES OF FAT ABSORPTION. 453 


found the reaction of the intestinal contents to be acid all the way from pylorus 
to cecum. 

Vaughan Harley! tested the reaction of the upper and lower halves of 
the small intestine, and of the large intestine, in three dogs which had been 
fed on milk, and found that the reaction was acid in all three portions. 

Moore and Rockwood? have recently studied the reaction of the intestine 
in the dog during fat absorption to different indicators, chosen with a view 
to determining, not only the reaction, but also the character of the acids or 
bases causing that reaction. The indicators used were litmus solution, methyl- 
orange, and phenolphthaléin. The reaction to litmus of the upper part of the 
small intestine was found to be acid, changing to alkaline at a somewhat 
variable point, situate two-thirds to three-fourths of the way from pylorus to 
eecum. The contents of the large intestine are commonly acid to litmus, 
while the reaction of the contents of the cecum lies intermediate between 
that of the contents of the ileum and that of the contents of the large in- 
testine, and may be either faintly alkaline or faintly acid. 

The reaction at the pylorus, and for some distance below, may be nearly 
neutral or even faintly akaline to litmus; as the distance below the pylorus is 
increased, the reaction always becomes more strongly acid at first, then less 
acid again, and finally faintly alkaline at the limit described above. On 
testing with the other two indicators, it was found that the reaction was 
invariably alkaline all the way to methyl-orange, and acid all the way to 
phenolphthaléin. 

These results seem at first sight confusing and contradictory, yet a 
consideration of the properties of the indicators used, not only renders them 
intelligible, but gives an indication as to the nature of the substances to 
which the contents of the intestine during fat absorption owe their reactions. 
An organic indicator only reacts to an acid which is stronger than the acid 
which it itself contains in its molecule; to a weaker acid it is stable, and 
hence shows no acid reaction; and in case the weaker acid is present as a 
salt, it decomposes that salt and reacts to the base with which it was com- 
bined, giving an alkaline reaction. Now, methyl-orange is a very stable, 
phenolphthaléin a very unstable, indicator, while litmus lies intermediate be- 
tween these two. Methyl-orange reacts sharply to the inorganic acids, less so 
to the stronger organic acids such as acetic acid, and not at all to carbonic acid 
and the weaker organic acids, including stearic, palmitic, and oleic acids. With 
alkaline salts of these weaker acids (carbonates, bicarbonates, and the soaps) 
it gives an alkaline reaction. Phenolphthaléin reacts to traces of the weakest 
organic acids, and to carbonic acid ; to normal sodiuin carbonate it is alkaline ; 
to sodium bicarbonate, neutral; with excess of carbonic acid, acid. Litmus 
reacts to even weak organic acids, but the reaction is feeble, and a considerable 
excess is necessary to give a clear reaction ; to carbonates and bicarbonates of 
the alkalies, it is alkaline. 


These considerations make it evident that the acid reaction of the 
upper part of the small intestine to litmus during fat absorption is due 
to weak organic acids, probably to dissolved acids set free from fats ;* 
while the alkaline reaction to methyl-orange can only be due to weak 
organic acids combined with alkalies, ze. in all probability to dissolved 
soaps. 

Since the acid reaction of the intestine during fat absorption is due 
to weak organic acids, the contention that soaps cannot be present falls 
to the ground. For the soaps would not be decomposed by these acids. 

An objection, and apparently at first sight a very serious one, to 


1 Journ. Physiol., Cambridge and London, 1895, vol. xviii. p. 2. 
? Ibid., 1897, vol. xxi. p. 58. 3 Vide infra. 


454 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


absorption in the form of soaps, is that urged by I. Munk, namely, the 
enormous quantity of alkali which would be required for such a purpose. 
Munk! reckons that to so combine with the fatty acids of 200 grms. of 
fat, about 40 grms. of sodium carbonate (Na,CO,) would be required. 
Now a dog of 25 kilos. can easily digest from 200 to 350 grms. of fat 
in twenty-four hours.2, Supposing only 200 grms. are digested, and that 
all this is absorbed as soaps and glycerin, about 40 grms. of sodium 
carbonate will be required for the purpose; now the total blood only 
contains, in such an animal, alkali equivalent to 6 grms. of Na,CO,; if 
the other fluids of the body be supposed to contain an amount of alkali 
equivalent to another 6 grms. of sodium carbonate, the total alkalinity is 
equivalent to that of 12 grms. of sodium carbonate.? Therefore, to 
suffice for the absorption of the fatty acids as soaps, from three to four 
times the total alkali of the body must pass out in the intestinal 
secretions, and be reabsorbed with the fatty acids, during twenty-four 
hours. This is obviously impossible ; therefore the fats are not absorbed 
as soaps and glycerin. 

This objection of Munk loses, however, most of its weight, when 
the probable processes taking place, in case fats are absorbed as soaps 
and glycerin, and synthesised again to neutral fats in the epithelial 
cells, are carefully considered. In the synthesis of fat from soap and 
glycerin within the cell, alkali is again set free in exactly equal amount 
to that in which it was used up in the intestine, and this alkali must be 
got rid of by the cell in some manner. Why should it not be sent back 
again into the intestine, and act as a carrier to a fresh quantity of fatty 
acid as soap into the cell? In such a fashion a very small amount of 
alkali would suffice to explain the carriage of all the 200 grms. of fat as 
dissolved soap and dissolved glycerin into the epithelial cells. 

It might possibly be further objected that soaps are only present in 
small quantity in the intestinal contents. But this applies also to 
alkali albumin, propeptones, peptones, and sugars; in fact, to all the 
products of the digestion of both proteids and carbohydrates. If soaps 
are normally absorbed by the epithelial cells, it is probable that these 
cells possess a selective capacity for soap absorption, as they do for many 
other products of digestion, and hence that the soaps are absorbed as 
they are formed, and never allowed to accumulate in appreciable 
quantity in the intestine. 

There is, then, no proof that soaps cannot be formed in the intestine, 
nor is there any impossibility or improbability in the way of all the fats 
being first decomposed into fatty acids, then converted into soluble 
soaps and absorbed as such. 

Theory of absorption as dissolved fatty acids—Another theory is, that 
the fats are absorbed in the form of dissolved fatty acids. 


The fatty acids of the fats are practically insoluble in water, but are 
soluble to a certain extent in bile, the solubility increasing with rising temper- 
ature. Strecker‘ stated, in 1848, that taurocholiec acid possesses the property 
of dissolving fat, fatty acids, and cholesterin in considerable quantity. This 
fact is mentioned by Strecker in connection with the difficulties attending the 


1 Virchow’s Archiv, 1880, Bd. lxxx. S. 11; 1884, Bd. xev. S. 408. 

2 Pettenkofer and Voit, Ztschr. f. Biol., Miinchen, 1873, Bd. ix. 8S. 30. 

° These figures must only be taken as argumentative data, overstepping the truth, and 
not as truly indicating the total alkalinity. 

4 Ann. d. Chem., Leipzig, 1848, Bd. Ixy. S. 29. 


SOLUTION THEORIES OF FAT ABSORPTION. 455 


preparation of taurocholic acid in a pure condition from bile. He did not 
pursue the subject further on its own account, and his statement is in part 
erroneous, for the neutral fats scarcely dissolve at allin bile. In 1858, Marcet+ 
published the results already described, showing the great solubility of the 
fatty acids in bile when heated above their melting points. Latschinoff? 
described a variable compound, or rather mixture, formed by taurocholic acid 
with a mixture of stearic and palmitic acids, which possesses certain crystallo- 
graphic properties, but no definite chemical composition. 


Altmann,? mainly on histological grounds, concluded that fats are 
not absorbed as an emulsion, but in some soluble form. 

Krehl,* under Altmann’s direction, obtained sections of the intestine, 
stained by osmic acid, from animals killed at varying times after feeding 
on fat (olive oil and cream). These preparations showed a gradual 
increase in the size of the globules with the advancement of the period 
of digestion. Also, it was observed that in the earlier stages the 
small fat globules showed a clear centre, surrounded by a dark ring. 
From these appearances it was judged that the formation of the fat 
granules was a gradual one from solution, and not from drops of fat 
emulsion. In considering the soluble form in which the fats are 
absorbed, Altmann rejects the idea that they are absorbed as soaps, 
chiefly on the ground that the reaction in the small intestine of the dog 
is acid, so that it cannot contain dissolved soaps ;° yet from such a por- 
tion of intestine, with an acid reaction and containing a clear fluid, the 
charged lacteals are often to be seen conveying away absorbed fat. 
Altmann cites the statements as to the solubility of the fatty acids in 
bile already mentioned,® and adds an experiment of his own, in which he 
shows that a considerable, but not too great, quantity of a solution of com- 
mercial glycerin soap,and then excess of hydrochloric acid, may be added 
to a solution of sodium glycocholate or taurocholate without producing 
any precipitation of either fatty or bile acid. From these data, and the 
observation of Munk that the fatty material found in the dog’s intestine 
during fat digestion may contain as much as 12 per cent. of free fatty 
acids, Altmann argues that the free fatty acids are dissolved in the 
intestine by the bile acids. As the fatty acids so dissolved are absorbed, 
fresh amounts of the neutral fats are decomposed, and the free fatty 
acids so formed pass into solution to replace those removed by absorp- 
tion. So that there is a cyclic process involving the decomposition of fats, 
solution of fatty acids in the bile acids present, absorption of these fatty 
acids by the intestinal cell, and regeneration of neutral fat within the 
cell, accompanied by the appearance of fat granules. 


Altmann did not quantitatively determine the amount of solubility of 
fatty acids in bile acids, bile, or intestinal fluid. The solubility in bile varies 
greatly with temperature, as is shown by Marcet’s experiments.’ At the 
temperature of the body the solubility is much less than at the temperature of 
fusion of the fatty acids, but is still considerable ; while at ordinary atmo- 
spheric temperature (14° to 15° C.) the solubility is very slight.® 

The solubilities of the fatty acids, and mixtures of these at or near the 


1See p. 444. 

2 Ber. d. deutsch. chem. Gesellsch., Berlin, 1880, Bd. xiii. S. 1911. 

3 Arch. f. Anat. uv. Physiol., Leipzig, 1889, Anat. Abth., Supp. Bd. S. 86. 

4 Thid., 1890, Anat. Abth., S. 97. 

> This objection is discussed under the soap-absorption theory. See p. 453. 

§ Except those of Marcet. “See p. 444. 

8 Moore and Rockwood, Journ. Physiol., Cambridge and London, 1897, Vol. xxi. p. 58. 


456 CHEMISTRY OF THE DIGESTIVE PROCESSES. 

> 
temperature of the body, have recently been determined by Moore and Rock- 
wood,! in the bile of the ox, pig, and dog, and in the mixed bile salts of ox 
bile, with the following results :— 

1. Pure palmitic and stearic acids are practically insoluble in ox bile at a 
temperature of 38° to 40° C., while oleic acid is easily soluble at this tempera- 
ture to the extent of 4 per cent. 

2. Of the mixed fatty acids of lard, beef-suet, and mutton-suet, respectively, 
lard acids are most soluble, mutton-suet acids least soluble, while beef-suet 
acids are intermediate. Thus in ox bile the solubilities are—lard fatty acids, 
3°D per cent. ; beef-suet fatty acids, 2°5 per cent. ; mutton-suet fatty acids, 2 
per cent. 

3. The solubility of the fatty acids in bile is only in part due to the bile 
salts. A strong solution (9 per cent.) of the bile salts of ox bile dissolves all 
three mixtures of fatty acids both more feebly and more slowly than bile itself. 
Mere removal of the ‘‘ pseudo-mucin” from bile greatly diminishes its solvent 
action on fatty acids. 

The same experimenters have shown that the filtered contents of the dog’s 
intestine, removed during fat absorption, are capable, in some samples, of 
digesting and dissolving at body temperature to a clear solution as much as 
4 per cent. of neutral fats. On cooling, the dissolved fatty material was 
’ thrown out of solution as fatty acids. This experiment shows that, in the dog 
at least,” fats can be dissolved and absorbed in solution as fatty acids. 

The solubilities of the mixed fatty acids in bile, stated above, are quite 
sufficient to account for the absorption of all the fats of the food in the form 
of dissolved fatty acids, since they exceed the concentrations in which the 
products of carbohydrate and proteid digestion are met with in the intestine. 
But this alone is not sufficient evidence to prove that in the normal course of 
events all the fat is absorbed in such form. 

The acids of the fats give an acid reaction with litmus. The bile used in 
the experiments arranged to determine the solubilities was at first strongly 
alkaline to htmus, but after it had dissolved the fatty acids it became markedly 
acid to that indicator. It follows, that a fluid with an alkaline reaction to 
litmus cannot hold in solution any free fatty acids. Now, in the intestine of 
the white rat, during active fat absorption, the reaction is commonly strongly 
alkaline to litmus, all the way from pylorus to ezecum, and is never acid to that 
indicator for a greater distance than 6 in. from the pylorus.® 

Further, even in the case of the dog, and in that part of the intestine where 
the reaction is acid to litmus, there are probably soaps as well as fatty acids in 
solution. This is shown by the behaviour towards litmus and methyl-orange 
of the contents of this part of the intestine. The acid reaction towards litmus 
is shown by the alkaline reaction to methyl-orange to be due to very weak 
organic acids ; at the same time, the alkaline reaction to methyl-orange also 
shows that there is an excess of bases present (above the amount necessary to 
combine with the strong acids), which is combined with very weak acids. 
The most probable conclusion, as such a state of affairs is met with during the 
digestion of an almost purely fatty meal (beef-suet), is that these weak acids are 
the acids of the fats (oleic, palmitic, and stearic) in combination as soaps. 
Hence, in that part of the small intestine of the dog where the reaction is acid 
to litmus, fat absorption is probably going on, partly in the form of dissolved 
fatty acids and partly in the form of dissolved soaps; in the part where the 
reaction is alkaline to litmus, wholly in the form of dissolved soaps. 

In those animals, such as herbivora, in which the reaction of the intestinal 
contents is strongly alkaline, it is probable that all the fat is absorbed as soaps. 

1 Loc. cit. 


2 Similar results were not obtained with filtered intestinal contents obtained from the 
rabbit or pig. 
3 Moore and Rockwood, Zoc. cit. 


—- - 


PASSAGE OF THE FAT TO THE LACTEALS. 457 


If a rabbit be killed some hours after a meal of oats, a certain amount of fat is 
shown to be in process of absorption by the whiteness of the lacteals, but the 
reaction of the contents of the small intestine is always markedly alkaline. 


It is probable, then, that in all animals a great part of the fat is 
absorbed dissolved in the form of soaps; but in some animals a part 
is also absorbed as dissolved fatty acids, while in others the entire 
quantity leaves the intestine in the form of soaps. 


These various theories as to the form in which fats enter the epithelial 
cell, may be summarised as follows :— 

‘Emulsion theories.—1. A small percentage of the fat is split up into 
fatty acids and glycerin, the fatty acids unite with the alkaline basis of the 
mixed secretions present in the intestine, and the rest of the fat is thereby 
converted into an emulsion, which is absorbed by the columnar cells. 

2. A considerable part of the fat is split up into fatty acids and glycerin, 
and absorbed as emzlsijied fatty acids and glycerin, which are synthesised 
to neutral fats by the columnar cells. 

Solution theories.—1. All the fat is split up into fatty acids and glycerin ; 
the fatty acids combine with alkaline bases to form soluble soaps; these and 
the dissolved glycerin are absorbed in solution, and synthesised to neutral 
fats in the columnar cells. 

2. All the fat is split up into fatty acids and glycerin; the fatty acids 
are dissolved as such by the intestinal fluid (the bile being that constituent 
which gives this solvent property to the fluid), these dissolved fractions of the 
fat are absorbed by the columnar cells, and by these are synthesised again to 
neutral fats. 

3. The processes indicated under solution theories 2 and 3 probably 
mutually replace each other to a variable extent in some animals, but in 
others absorption takes place entirely in the form of soaps. 


Passage of the fat from the epithelial cells to the lacteals.— 
In whatever form the fat passes into the columnar cells, it is certain 
that it is here converted again into fat. During active fat absorption 
these cells become gorged with fat globules of varying dimensions. It 
is agreed by all observers that this fat passes from the epithelium to 
the lacteals in the form of an emulsion, but there is some difference of 
opinion as to the fashion in which it is conveyed. 

It has already been stated that the tissue of the villi, especially 
during active fat absorption, contains immense numbers of leucocytes. 
These are found not only in the subepithelial tissue, but between the 
epithelial cells. The number in this position is greatly increased during 
absorption, and at this time lymphoid cells occur also in the lacteals, 
but “are found more numerously in the lacteals of the villi than in 
those which are more deeply seated, and, most numerously of all, near 
the blind end of the lacteal. That they pass into this vessel from 
the surrounding lymphoid tissue is certain, for a lymphoid cell may 
often be seen, fixed by the reagent employed for hardening the tissue, 
in the act of passing through the wall of the lacteal.”1_ After a meal 
containing fat, these lymphoid corpuscles contain granules, which stain 
black with osmic acid; many of these are soluble in munis so that they 
are unquestionably composed of fat. 


1 Schafer, Internat. Monatschr. f. Anat. u. Histol., Leipzig, 1885, Bd. ii. S. 6. The 
greater part of the description of the carriage of fat by leucocytes, between epithelium and 
lacteal, given in the text, is abstracted from this source. 


458 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


These appearances led Schiifer1 to express the view that the 
lymphoid corpuscles have an important function in taking up the fat 
from the epithelial cells, and carrying it towards and into the lacteal, 
where they set the fat free by disintegrating. No fat particles are, as a 
rule, found between the epithelium and the central lacteal, save such as 
are embedded in lymphoid corpuscles. Nor is there any channel of 
communication between the epithelial cell and the lacteal, as was 
formerly supposed, by which the fat globules might be carried into the 
lacteal. The epithelial cells never penetrate the basement membrane, 
nor are they continued into the cells of the retiform tissue beneath. 
Wiemar? admits the presence, during fat absorption, of fat granules in 
the leucocytes, but from the small amount of fat so found, compared 
with that in the epithelial cells, considers that the leucocytes can only 
be of secondary importance. In this connection it should be noted that 
Schiifer ® has pointed out that the relative amount of fat granules in 
leucocytes and epithelial cells varies with the activity of absorption. 
“When the absorptive activity is feeble, or when the amount of fat in 
the chyme is relatively small, there may be little or no fat in the 
columnar epithelial cells, although the amoeboid cells between them may 
be gorged with fat granules. In frogs fed with lard in the spring, 
fatty globules are still abundant in the columnar epithelial cells on the 
eighth day after the feeding, whereas, in frogs similarly fed in November, 
the greater part of the fat was discharged per anum, by the third day, 
very little being absorbed, and what was being taken up during that 
time was only to be found in the ameeboid cells, none at all being 
present in the epithelial cells themselves.” This seems to indicate that, 
when the rate of absorption is slow, the amceboid cells are able to keep 
pace with it, but when the supply is too abundant for this, the columnar 
cells act as temporary storehouses, and become filled with granules, 
which are afterwards carried off by the ameeboid cells. 

Heidenhain* ascribes only a secondary importance to the leuco- 
cytes. He gives as grounds for this opinion—(1) That in newly-born 
puppies, which have already sucked, and in which milk absorption is 
going on, there are scarcely any leucocytes present in the epithelium, so 
that there is no constant connection between fat absorption and the 
presence of leucocytes. (2) Leucocytes containing granules, which stain 
black with osmic acid, are to be found in the erypts of Lieberkiihn, into 
which fat cannot enter from the intestine. (3) The material which is 
stained black with osmic acid is chiefly something else than fat, since 
it stains with acid-fuchsin, and cannot be washed out of adhesively 
mounted sections by ether or xylol.6 Heidenhain® admits, however, 
that in the guinea-pig fat is undoubtedly present in considerable 
quantity in the ameeboid cells during fat absorption. 

Heidenhain? still adheres to the emulsion theory of absorption, but 


1 Quain’s ‘‘ Anatomy,” 8th edition, 1876, vol. ii. p. 363; ‘‘ Pract. Histology,” 1876, 
p- 194; Internat. Monatschr. f. Anat. u. Histol., Leipzig, 1885, Bd. ii. 8. 6; Arch. f. d. 
ges. Physiol., Bonn, 1884, Bd. xxxiii. S. 513. Schifer’s observations were chiefly made 
upon the frog and rat. 

2 Tbid., Bd. xxxiii. 8. 532. 

3 Internat. Monatschr. f. Anat. u. Histol., Leipzig, 1885, Bd. ii. S. 6. 

+ Arch f. d. ges. Physiol., Bonn, 1888, Bd. xliii. Supp. Heft, S. 82. 

>It should, however, be pointed out, that after prolonged treatment with osmic acid, 
fats tend to become insoluble in these fluids. 

3 Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xliii., Supp. Heft, S. 103, figs. 39 and 40, plate iv. 

Ibid., 8. 88. 


ABSORPTION OF FATS. 459 


offers no explanation of the mode in which the fat granules get into 
the epithelial cells; he considers that the bile must essentially assist 
in the process, partially by aiding the emulsification of the fats, and 
partially by making the surface of the epithelium capable of being 
wetted by the fats, which naturally facilitates the absorption. He 
is further of opinion that the fat globules are passed on out of 
the columnar epithelial cells by means of the contractions of the 
cell protoplasm; and that these on their further path to the lacteal, 
apart from the small part eaten up by the leucocytes, pass in a 
free condition through the intercellular spaces, and are first broken up 
into the very fine granules characteristic of chyle when passing into 
the lacteal. 

The effects of absence of the pancreatic juice or bile on the 
absorption of fats.—The results on record as to the absorption of fat, 
when the action of the pancreatic juice is removed by excision of the 
pancreas, ligature of the pancreatic ducts, or establishment of a pan- 
creatic fistula, vary considerably ; although there is a concurrence of 
opinion amongst recent observers! that the absorption of fat is 
hindered to a greater or lesser extent by the absence of the secretion. 
Minkowski? and Abelmann ® found that no fat, except that of milk, was 
absorbed after complete removal of the pancreas, and this was only 
absorbed to the extent of 28 to 53 per cent.; the failure of absorption 
was not due to absence of fatty acids, for 80 per cent. of the ether 
extract of the feces was found to be free fatty acid. 


Minkowski believes that the absorption of the milk fat is due to this emul- 
sion being able to withstand an acid reaction, but the absorption of other fats, 
when pancreas is given with the fat, points rather to some specific function 
of the pancreatic juice, for this pancreatic tissue could not materially alter the 
reaction of the intestine ; besides, fat absorption takes place normally from 
the dog’s intestine in presence of an acid reaction. Sandmeyer* found in 
dogs in which the pancreas had been partially extirpated, that the amount of 
fat absorption was very variable; occasionally no fat at all was absorbed, 
and at other times, with the same animal, 30 and even 78 per cent. of the fat 
was absorbed. 

Teichmann ® found by microscopic examination that fat absorption in the 
rabbit was not influenced to any marked extent by ligature of the pancreatic 
duct. Fr. Miiller ® observed a considerable amount of fat absorption in a patient 
with a pancreatic fistula. Vaughan Harley ‘ extirpated the pancreas completely 
in dogs, killed the animals a varying number of hours after feeding on milk, 


1Qn the other hand, Cohn (Bul/. Acad. de méd., Paris, 1856) found that the absorp- 
tion of fat was not affected when the pancreatic juice was allowed to escape from a fistula. 
Cash (Arch. f. Anat. u. Physiol., Leipzig, 1880, S. 323) ligatured both pancreatic ducts in the 
dog, and found that fat was still absorbed. Schiff (Jahresb. ii. d. Fortschr. d. Thter- 
Chem., Wiesbaden, 1872, Bd. ii. S. 222) shut out the pancreatic secretion by injecting 
paraffin into the duct, and found that fat to the amount of 120 to 150 grms. per diem was 
still absorbed. 

2 Von Mering and Minkowski, Arch. f. exper. Path. u. Pharmakol., Leipzig, 1890, Bd. 
xxvi. S. 371. 

8 Inaug. Diss., Dorpat, 1890 ; Minkowski, Berl. klin. Wehnschr., 1890, S. 333. 

4 Ztschr. f. Biol., Miinchen, 1895, Bd. xxxi. S. 12. See also Rosenberg, Arch. f. Anat. 
u. Physiol., Leipzig, 1896, Physiol. Abth., S. 535. 

5.“* Mikroskop. Beitr. z. Lehre von der Fettresorption,” Diss., Breslau, 1891. 

6 Ztschr. f. klin. Med., Berlin, 1887, Bd. xii. S. 45. Defective fat absorption, however, 
undoubtedly accompanies disease of the pancreas, or occlusion of its duct in most cases; see 
Bright, Med.-Chir. Trans., London, 1832; Zieh], Deutsche med. Wchnschr., Leipzig, 1883, 
S. 588; le Nobel, Deutsches Arch. f. klin. Med., Leipzig, 1888, Bd. xliii. S. 285. 

7 Journ. Physiol., Cambridge and London, 1895, vol. xviii. p. 1. 


460 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


and estimated the amount of fatty material in the stomach and intestine. The 
amount so found was usually slightly in excess of that given in the food, the 
surplus being probably due to intestinal secretion or excretion. Lewin,! asa 
result of microscopic examination of sections of the intestine, concludes that fat 
absorption does not take place in a normal manner if bile or pancreatic juice, or 
both, are kept from entering the intestine. He also found under such cireum- 
stances that the lacteals did not present the usual milky appearance which 
accompanies fat absorption. 


The effect of a biliary fistula on fat absorption seems to be identical 
with that of a pancreatic fistula; exactly the same kinds of results have 
been recorded in the two cases. All observers are agreed that so much 
fat cannot be absorbed in presence of a biliary fistula as when bile has 
access to the intestine, but, while some find fat absorption practically 
arrested, others have observed that a considerable, nearly normal, amount 
of fat can still be disposed of. As in the ease of absence of the pan- 
creatic secretion, most of the unabsorbed fat is found in the feeces as 
fatty acid.? 


Rohmann * also found that sodium soaps were not absorbed, but were 
converted into free fatty acids, and appeared as such in the feces. Bidder 
and Schmidt+ state that normal dogs can digest as much as seven times the 
quantity of fat which can be disposed of by dogs with fistula of the gall bladder, 
and that, while during fat absorption in a normal dog the lacteals are filled with 
milky chyle, they are, under similar conditions in a dog with a biliary fistula, 
filled with a yellow or slightly opalescent fluid. 

C. Voit® estimates the average loss of fat at 22°2 to 34:7 per cent.; Munk,® 
at 33°] per cent. ; Réhmann,’ at 48°5 to 58-4 per cent. ; Noél Paton,’ at 34°58 
per cent.; Dastre,® at 57°65 per cent. Munk?!° found that the absorption of fats 
of high melting point (mutton) suffered more than that of fats of low melting 
point (hog’s lard) ; of the former but 35:5 per cent. was utilised, of the latter 
67 per cent. He also found that the free fatty acids in the absence of bile were 
absorbed equally well, in fact slightly better, than the corresponding neutral 
fats. Dastre! ligatured the ductus choledochus, and made a fistula between 
the gall bladder and small intestine much lower down (60-150 em.) ; he 
observed, after a meal of fat, that the lacteals were only injected with milky 
chyle below the artificial point of entry of the bile. As Dastre himself 
remarks, the result is more elegant than decisive. It is only qualitative in 
character, and does not show quantitatively the share taken by pancreatic 
juice and bile in fat absorption. Hédon and Ville ” established first a biliary 
fistula, and afterwards removed nearly all the pancreas, leaving just enough of 
the tail to preserve the animal alive, and destroying all communication with 
the intestine. In this manner both bile and pancreatic juice were kept out of the 
intestine, and under such conditions the digestion and absorption of fat was 


1 Arch. f. d. ges. Physiol., Bonn, 1896, Bd. lxiii. 8.171. Lewin removed the influence of 
both secretions by making a Thiry-Vella fistula of that part of the duodenum into which 
the ducts open. 

* Rohmann, Arch. f. d. ges. Physiol., Bonn, 1882, Bd. xxix. S. 509 ; I. Munk, Virchow’s 
Archiv, 1890, Bd. exxii. S. 313 ; Hédon and Ville, Compt. rend. Soc. de biol., Paris, 1892, 
tome xliv. p. 309. See, however, Dastre, Arch. de physiol. norm. et path., Paris, 1891, 
tome xxili. p. 186. 


3 Loc. cit., S. 582. + Die Verdauungssifte,” etc. 
° “Beitr. z. Biologie,” Jubiliumsschrift f. v. Bischoff, Stuttgart, 1882. 
6 Virchows Archiv, 1890, Bd. exxii. S. 302. 7 Loc. cit. 


8 Rep. Lab. Roy. Coll. Phys., Edin., 1891, vol. iii. p. 214. The case was one of a com- 
plete biliary fistula in a woman. 
9 Loe. cit. 10 Loc. cit.,.S. $24,-825. U Loe. cit. 12 Loc. cit. 


ihe Ls) 


ABSORPTION OF FATS. 461 


studied. It was found that food passed very rapidly through the alimentary 
eanal without much modification, scarcely any fat was absorbed, but it was 
nearly all converted into fatty acid. 


These varied results may be summed up as showing that both the 
pancreatic juice and the bile are powerful aids in the digestion and 
absorption of fats, but neither is absolutely indispensable. 

The view to be taken of the part played by bile and pancreatic juice 
in fat absorption must naturally vary with the view held as to the form 
in which fat is absorbed. 

1. It may be urged that, in the absence of pancreatic juice, a sufficient 
supply of fatty acid is not set free for emulsification of the remainder. 
Since bile (or bile salts) very much hastens the fat-splitting action of 
pancreatic juice,! the absence of bile would have a very similar effect to 
that of pancreatic juice itself. A serious objection to this explanation 
hes in the fact that in defective absorption, due to the absence of either 
bile or pancreatic juice, nearly all the unabsorbed fat is found in the 
feeces as free fatty acid. 

It might be claimed that this fat-splitting, probably by bacterial 
action, takes place much lower down in the intestine, at a less favourable 
position for absorption, and that a considerable part of the intestine is 
traversed before a sufficient amount of fatty acid is formed. But in the 
feeces as much as 80 per cent. of the total fat is as free fatty acid, while 
only about 5 per cent. is required for spontaneous emulsion ; besides, the 
fat of the food contains nearly sufficient fatty acid to begin with, so that 
this contention has little weight. 

2. Another view which has been held is, that in the absence of either 
bile or pancreatic juice the intestinal reaction is acid, so that no emul- 
sion can take place, and hence the fat cannot be absorbed. It is not, 
however, claimed that such an acid reaction is due to free hydrochloric 
acid, since the remaining alkaline secretions are still more than sufficient 
to neutralise this, and active fat absorption has often been observed in 
presence of an acid reaction due to organic acids. 

3. It has been supposed that the absence of the proteid of the 
pancreatic juice has an unfavourable effect on the formation of an 
emulsion (Minkowsk1). 

4, A theory advanced by v. Wistinghausen? was that the bile aided 
fat absorption by mechanically wetting the epithelial cells with a fluid 
which rendered the passage of the fat easier. He claimed that oil 
stood higher in capillary tubes wetted with bile than in similar tubes 
wetted with water, and that oils or melted fats passed more rapidly 
through a membrane wetted with bile than through one wetted 
with water. These results have not, however, been confirmed by other 
observers.* 

5. It has also been supposed that the bile directly stimulates 
(chemically) the epithelial cells of the intestine to increased fat absorp- 
tion, and that in the absence of the bile this stimulus is absent. Under 
these conditions the epithelial cells either do not absorb fat as an emul- 


1 Rachford, Journ. Physiol., Cambridge and London, 1891, vol. xii. p. 87. 

2 Translation in Arch. f. Anat. u. Physiol., Leipzig, 1873, S. 187, by J. Steiner. See 
also Schiff, Untersuch. z. Naturl. d. Mensch. u. d. Thiere, 1857, Bd. ii. S. 345 ; Heiden- 
hain, Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xliii. Supp. Heft, S. 91. 

* Groper, Arch. f. Anat. u. Physiol., Leipzig, 1889, S. 505. 


462 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


sion at all, or only absorb it. at a greatly diminished rate.t There is no 
experimental evidence in support of this theory, and a great objection to 
it is that bile is constantly present in the intestine, and is not poured 
out in association with the presence of fat; such are not the proper 
conditions for a stimulus, which ought, if itis to be effective, to be inter- 
mittent, and only be called into action when required. 

6. All the previous views rest on the assumption that the fats are 
absorbed in the form of an emulsion. If, on the other hand, the fats are 
absorbed in soluble forms as fatty acids or soaps and glycerin, the most 
obvious explanation of the action of bile and pancreatic juice in assisting 
absorption is, that these secretions increase the solubility of the fatty 
acids or soaps. 

In the absence of bile or pancreatic juice, the fatty acids are not so 
soluble in the intestinal fluid, and so the absorption is defective, and the 
insoluble fatty acids appear in the feces. In support of this the fact 
may be recalled that the bile salts possess the power of dissolving the 
insoluble soaps of the alkaline earths.? 

Channels of absorption of the fats—There is no doubt that the 
lacteals are the main channel by which the fats are carried away from 
the intestine, but it is by no means so clear that all the fat goes by this 
route. The amount of fat absorbed from the intestine after a fatty meal 
can easily be determined by weighing the amount of fat ingested, and that 
remaining in the alimentary canal when digestion is nearly complete, and 
taking the difference, which must be the amount absorbed. The amount 
of fat poured into the blood by the thoracic duct during the same period 
can also be determined, by inserting a cannula into the duct and collecting 
the chyle, from which the fat is afterwards extracted and then weighed. 
The amount thus carried by the thoracic duct during the period of active 
absorption is always much less than the total quantity absorbed; it has 
never been found to amount to more than 60 per cent., and is usually 
much less than this.2 The fate of the balance of the fatis unknown; the 
first suggestion occurring to the mind, that it travels by the alternate 
path of the portal circulation, has not been found to fit the experimental 
facts. The portal vein during fat digestion does indeed contain an 
abnormal amount of finely emulsified fat, but so does all the blood of the 
body, and the presence of the fat is due to the admixture with the blood 
of the chyle carried by the thoracic duct. On diverting from the blood 
this supply of fat, by means of a cannula inserted into the thoracic duct, 
Zawilski found scarcely any fat in the blood during fat absorption. 
Neither is there any difference during fat absorption in the percentages 
of fat present in portal and carotid blood. It would seem from this 
that almost all the fat is carried by the lacteals, but that part is 
removed somewhere in the lymphatic system between the lacteals and 
the opening of the thoracic duct; it may be in the lymphatic glands, 
but the subject requires further investigation. 


1 Rohmann, Arch. f. d. ges. Physiol., Bonn, Bd. xxix. 8. 509; Minkowski, Berd. med. 
Wehnschr., 1890, No. 15, S. 333; Lewin, Arch. f. d. ges. Physiol., Bonn, 1896, Bd. 1xiii. 
S. 186. 

2 See p. 392. 

3 Zawilski, Arb. a. d. physiol. Anst. zw Leipzig, 1867, Bd. xi. S. 147; Walther, Arch. 
f. Anat. u. Physiol., Leipzig, 1890, S. 329; Frank, <bid., 1892, S. 497; Munk u. Rosen- 
stein, Virchow’s Archiv, Bd. exxili, S. 484. 

4 Heidenhain, Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xliii., Supp. Heft, S. 95. 

5 See M. Foster, ‘‘ Text-book of Physiology,” pt. ii. p. 513. : 


BACTERIAL DIGESTION. 463 


After a full meal of fat, absorption, in the.case of the dog, goes on 
for about thirty hours. At the height of absorption, the chyle in the 
thoracic duct may contain as much as 15 per cent. of fat. Twenty-one 
hours after a meal of 150 grms. of fat, Zawilski* still found in the stomach 
9-74 grms., in the intestine 6°24 grms.; in thirty hours all but traces 
have disappeared from both stomach and intestine. Throughout this 
period of digestion, according to the same observer, the amount of fat in 
the intestine at any time remains practically constant (6:24 to 9-9 grms.), 
from which it would seem that the rate at which the fat is allowed to 
pass the pylorus is regulated by the amount of fat already present in the 
intestine. 

None of the soap which may be formed during fat digestion and 
absorption probably ever enters the general circulation as such, but is 
reconverted into neutral fat beforehand; as Munk? has shown, soaps , 
of the alkalies intravenously injected produce poisonous effects, closely 
resembling those obtained on injection of albumoses. 

As might be expected from their similar chemical constitution, the 
lecithins are decomposed in the same manner as the fats by the steapsin 
of the pancreatic juice, the products of the reaction being glycero- 
phosphoric acid, neurin, and fatty acids. These products are probably 
absorbed, as is shown by their absence in the feces after the administra- 
tion of lecithin by the mouth; as well as by the increase of phosphates 


in the urine after feeding on foods, such as yolk of egg, rich in lecithin.? 


BACTERIAL DIGESTION. 


The food in the alimentary canal is acted upon, not only by the 
digestive secretions and their enzymes, but to a greater or less extent by 
certain bacteria which are never entirely absent, although the amount of 
their action varies greatly, under healthy conditions, with the nature of the 
food and the class of animal. Under abnormal conditions the growth of 
these organisms may be greatly increased, and nutrition be seriously 
impaired, by their turning to their own uses the products of normal 
digestion, and leaving only for the service of the animal, degradation- 
products, inadequate or wholly unsuited for the purposes of its meta- 
bolism. Along with this increased growth of the bacteria normally 
present in the stomach, conditions may become so changed as to favour 
the growth of other bacteria, often pathogenic in character, which find 
under normal conditions no favourable soil for their growth in the 
intestinal contents, and thus various forms of disease may be introduced. 
We have here, however, only to deal with the changes induced by 
bacteria under a normal condition of the alimentary canal. 

In dealing with the function of the free hydrochloric acid of the 
gastric juice, it has already been stated that this completely stops all 
bacterial action,* so that it is only in the first stage of gastric secretion, 
- before the acidity has become marked, that any bacterial changes can occur. 

Proteids are not attacked during this first short stage (twenty to 
forty minutes) of gastric digestion, but carbohydrates undergo to a 


T Loc. cit. 2 Arch. f. Anat. u. Physiol., Leipzig, 1890, Supp. Bd., S. 116. 

3 A. Bokay, Ztschr. f. physiol. Chem., Strassburg, 1877, Bd. i. 8. 157; see also Hase- 
broek, zbid., 1888, Bd. xii. S. 148. 

4 See p. 364. 


464 CHEMISTRY OF T2FE- DIGESTIVE PROCESSES. 


slight extent lactic fermentation.1 A certain amount of decomposition 
of neutral fats also occurs during gastric digestion, yielding fatty acids, 
but it is not certainly known whether this is due to bacterial action or 
not.” 

Intestinal bacterial digestion—Reaction of the intestine.—There 
is considerable difference of opinion both as to the amount of decom- 
position of foodstuffs due to bacterial action which goes on in the 
intestine, and as to the importance of such a decomposition as a normal 
factor in digestion. 

The extent of bacterial action can evidently be more accurately 
gauged by the amount of bacterial decomposition products formed than 
by the presence in the intestine of bacteria, which may not there be in 
a very active condition. 

Judged by this standard, the amount of proteid decomposition due 
to bacteria which takes place in the small intestine is excessively small, 
while a considerable amount takes place in the cecum and large intes- 
tine generally. When carbohydrates and proteids are present in the 
same solution along with various bacteria capable of attacking them, 
the carbohydrates are first attacked, the action being accompanied by 
the formation of certain organic acids; at a later stage the proteids are 
attacked and decomposed. This has been shown by Maly, who took 
mucous membrane of the stomach, placed it in a solution of cane-sugar, 
and kept the mixture at body temperature for several days. The lactic 
acid formed by the decomposition of the sugar was neutralised from 
time to time, and it was found that the process continued without a 
trace of putrefaction appearing, until all the sugar had been converted 
into lactate; then first appeared, often somewhat suddenly, an intense 
putrefactive ‘odour, and the proteids began to be decomposed. 

It is probable from this that, mm the body, bacterial action on carbo- 
hydrates precedes that on proteids; and it has been supposed by some 
that such an action commences with considerable intensity im the 
duodenum, and persists throughout the entire length of the small 
intestine, so involving bacterial decomposition of a large share of the 
carbohydrate food. 

This opinion rests chiefly on the observation that the acid reaction 
of the chyme in the stomach, due to hydrochloric acid, becomes replaced 
by an acid reaction, due to or ganic acids, in the small intestine. These 
organic acids are supposed to be set free by the action of certain bacteria, 
found in the small intestine, upon the carbohydrate food. 


Such a result has been obtained by Macfadyen, Nencki, and Sieber,* from 
observations made on a case of anus preternaturalis i man, in which the 
fistula occurred quite at the lower end of the ileum. The intestinal contents 
arising from a mixed diet, consisting principally of animal food, had as they 
flowed from the fistula an acid reaction, equivalent to that of a solution of 
1 per mille of acetic acid; this reaction was principally due to acetic acid, 


1 In this process hydrogen gas is set free along with lactic and traces of other acids ; 
under abnormal conditions the amount of gas may be greatly increased. See E. Wissel, 
Ztschr. f. physiol. Chem., Strassburg, 1895, ‘Bd. xxi. S. 234, where the literature of this 
subject up to that date is given. 

* Marcet, Proc. Roy. Soc. London, 1858, vol. ix. p. 306; Cash, Arch. f. Anat. u. 
Physiol., Leipzig, 1880, S. 323. 

3 Hermann’s ‘‘ Handbuch,” Bd. v. (2), S. 239. 

4 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1891, Bd. xxviii. S. 311, reprinted in Journ. 
Anat. and Physiol., London, 1891, vol. xxv. p. 390. See also C. A. Ewald, Virchow’s Archiv, 
1879, Bd. lxxv. 8. 409; and Jakowski, Arch. d. sc. biol., St. Pétersbourg, 1892, tomei. p. 539. 


ACTION OF INTESTINAL BACTERIA ON PROTEIDS. , 465 


accompanied by traces of fermentation and paralactie acid, volatile fatty acids, 
succinic acid, and bile acids. Hydrochloric acid was not present. The 
mixture had very little odour; occasionally the slight odour it had was faintly 
putrefactive, resembling indol, but usually it was more like that of volatile 
fatty acids. These authors state that it is the organic acids present in the 
small intestine which limit the bacterial decomposition of carbohydrates, and 
prevent the putrefaction of proteids. 

On the other hand, Moore and Rockwood! state that the reaction of the 
intestine in various classes of animals (dog, cat, white rat, guinea-pig, and 
rabbit) is not normally acid throughout its entire length, and that the 
alkalinity increases in passing down the intestine. 

The presence of fat in the food causes in carnivora an acid reaction, which 
persists until the lower third of the intestine is reached. This acid reaction is 
due to very weak organic acid, most probably to the acids of the fats dissolved 
by the agency of the bile.2 The alkalinity is much greater in herbivora than 
in carnivora, although herbivora consume much more carbohydrate food than 
carnivora. Also, in carnivora, the alkalinity is markedly increased by carbo- 
hydrate food; this would not be the case if any considerable bacterial 
decomposition of carbohydrates took place in the small intestine, but the 
alkalinity would diminish from increased formation of organic acids. It is 
therefore probable that in these animals any extensive bacterial decomposition 
of carbohydrates that may occur, like that of proteids, takes place in the 
large intestine, and by analogy the same is probably the case in. the human 
intestine. 

Considerable importance has been attached to the normal action of bacteria 
in the intestine, and it has even been supposed that the presence of bacteria 
is essential to life. Such a view has recently been shown to be erroneous by 
an elaborate and painstaking research carried out by Nuttall and Thierfelder,? 
who obtained ripe foetal guinea-pigs, by means of a Cesarean section, carried 
out under strict antiseptic precautions. They introduced the animals immedi- 
ately into an aseptic chamber, through which a current of filtered air was 
aspirated, and fed them hourly on sterilised milk day and night for over eight 
days. 

The animals lived and throve, and increased as much in weight as healthy 
normal animals, subjected to a similar diet for the purpose of controlling the 
results. Microscopic examination at the end of the experiment showed that 
the alimentary canal contained no bacteria of any kind, nor could cultures of 
any kind be obtained from it. The same authors, in a subsequent paper, 
describe the extension of their research to vegetable food ; this was also digested 
in the absence of bacteria. Under such conditions cellulose was not attacked ; 
hence they consider that the chief function of this material is to give bulk and 
a proper consistency to the food, so as to suit the conditions of herbivorous 
digestion. 


Action of the intestinal bacteria on proteids.—The changes brought 
about in the intestine are very similar and probably identical with those 
which occur when proteids undergo putrefaction in the air, with this 
important exception, that those putrefactive bacteria which produce the 
class of poisonous nitrogenous (alkaloidal) bases known as ptomaines do 
not grow under normal conditions in the intestine. This may be due to 
the intestinal contents not furnishing a suitable medium for their growth, 
or to the time of putrefaction in the intestine not being sufficiently 
prolonged. Ptomaines, and especially poisonous ones, are formed only in 


1 Journ. Physiol., Cambridge and London, 1897, vol. xxi. p. 373. 
* See ‘‘ Digestion and Absorption of Fats,” p. 454. 
3 Ztschr. f. physiol. Chem., Strassburg, 1895, Bd. xxi. S. 109; 1896, Bd. xxii. S. 62. 


VOL. I.—30 


466 CHEMISTR Y¥.OF THE DIGESTIVE PROCESSES. 

the later stages of putrefaction. It has also been suggested that the 
cause may be the absence of oxygen from the intestine, the ptomaine- 
forming bacteria bemg aérobic. That the bacteria which produce 
ptomaines are present in the intestine, is shown by the fact that cultures 
producing ptomaines may be obtained by sowing from the intestinal 
contents into suitable media! At any rate, ptomaines even in traces are 
not to be found in the intestinal contents; and it is fairly certain that 
they are not produced there, as most of them, absorbed even in minute 
doses, are capable of producing profound toxic effects. 

The first stages in the action of bacteria on proteids are very similar 
to those induced by trypsin; they can also be brought about by enzymes 
extracted from the bacteria? but, according to Kiihne3 are not due to 
trypsin, which is never formed in bacterial “putrefaction, 

The first action is the solution of the proteid, if this is not already 
dissolved. Solution takes place much more slowly than im the case of 
the digestive enzymes, the complete solution of fresh fibrin thoroughly 
infected with intestinal bacteria in faintly alkaline solution being a 
process of some days’ duration.4 Albumoses, peptones, and the other 
products of tryptic digestion are next formed, but the amount of these 
present at any time is never great, since they are gradually broken up 
as they are formed into more advanced degradation products. In the 
presence of albumoses or peptones, the native proteids are very faintly 
attacked by the bacteria, until these have first been disposed of. 
Neumeister * has shown that, when peptone is added to putrefying blood 
or proteid, its quantity is not increased by the continuance of the putre- 
factive process, but rather diminished until it finally disappears. 

The proteid molecule probably contains a large number of both 
fatty and aromatic radicles, but all those belonging to the aromatic 
group yield, under the action of trypsin, only one substance, namely, 
tyrosine. The same is true of all artificial modes of decomposition which 
do not act too intensely on the primary products of decomposition.® 
But with the decomposition produced by bacteria, the case is different, 
and several aromatic compounds are formed. 

These are in part produced by further action on tyrosine, formed in 
an earlier stage, and in part spring from a specific action of the bacteria 
on the proteid, without the intervention of tyrosine. Only some of these 
products of bacterial decomposition have been hitherto found in the 
intestinal canal; the others are either, under the different conditions, not 
formed there, or are so rapidly absorbed and altered that they cannot 
be detected in the intestinal contents. 

The chief aromatic compounds derived from the bacterial decomposi- 
tion of proteids are:—(a) Tyrosine, and its derivatives, paraoxyphenyl- 
propionic acid (hydroparacumarie acid), and paraoxyphenylacetic acid, 
as well as phenylpropionic and phenylacetic acids,’ of which the fore- 
going are the oxy- or hydroxy-acids, also parakresol and phenol. 


1 Brieger, Deutsche med. Wehnschr., Leipzig, 1887, S. 469; Baumann u. Udransky, 
Ztschr. f. physiol. Chem., Strassburg, 1889, Bd. xiii. 8. 579. 

2 See p. 313. 

3 Untersuch. a. d. physiol. Inst. zu Heidelberg, 1878, Bd. i. S. 291. 

4 Bienstock, Ztschr. f. klin. Med., Berlin, 1884, Bd. viii. S. 1. 

5 Ztschr. f. Biol., Miinchen, 1890, Bd. xxvii. S. 335; ‘‘ Lehrbuch, ” Th. 1, S. 207. 

6 Kiihne obtained indol by the fusion of proteid with caustic alkali, Ber. d. deutsch. 
chem. Geselisch., Berlin, 1875, Bd. viii. S. 206. 

7 See E. Salkowski, “Zisehr. J. physiol. Chem., Strassburg, 1885, Bd. ix. S. 491. 


ACTION OF INTESTINAL BACTERIA ON PROTEIDS. 467 


(b) Substances formed directly and not from tyrosine—indol, skatol, and 
skatolcarbonic acid. 

Of these substances, Zumft? found indol, skatol, phenol, and _para- 
kresol in the large intestine of man, but skatolearbonic acid was absent ; 
this latter acid has not yet been detected in the intestine. According 
to E. Salkowski, it is excreted unchanged in the urine, and he states that 
he has detected it in normal urine.? 

These several substances may now be considered seriatim. 


Derivatives of tyrosine formed in putrefaction.°—Hydroparacumaric acid, 
or paraoxyphenylpropionic acid (HO.C,H,.C,H,.COOH) crystallises from 
water in anhydrous monoclinic crystals, melting at 125°-128° C., soluble 
in water, alcohol, and ether. It gives a transient blue coloration with ferric 
chloride, and a red coloration or red precipitate when boiled with Millon’s 
reagent. It is the oxy-acid of phenylpropionic acid, which has also been 
found among the putrefaction-products of proteids. Phenylpropionic acid 
erystallises in slender needles, melting at 47°-48° C. (B-Pt. 280° C.). As 
follows from its constitution, its solutions do not give Millon’s reaction. 

Paraoxyphenylacetic acid (HO.C,H,.CH,.COOH) crystallises from water 
in prismatic crystals, melting at 148° C., and soluble in water, alcohol, and 
ether. With ferric chloride it gives a faint violet coloration, changing to 
a dirty grey-green. It also gives Millon’s reaction. Phenylacetic acid 
erystallises in scales, which melt at 76°'5 C. 

Phenol and parakresol* ave also formed in the bacterial decomposition of 
tyrosine; they are absorbed from the alimentary canal, and after conversion 
into ethereal sulphates are excreted in the urine. The amount of these 
ethereal sulphates in the urine gives a measure of the amount of bacterial 
decomposition going on in the intestine.° 

Tyrosine and its derivatives are very closely related to one another. In 
the derivation of these compounds, according to Baumann,° tyrosine (paraoxy- 
phenyl-a-amidopropionic acid) undergoes reduction, ammonia being split off, 
and hydroparacumaric acid (paraoxyphenylpropionic acid) formed. This 
compound, by a series of oxidations, accompanied by a splitting off of carbon- 
dioxide, yields paraoxyphenylacetic acid and parakresol. Parakresol is said 
to similarly yield phenol. 


These changes are illustrated by the following equations :— 


Ea) EY) 
Se + H,=C,Hy¥ __+NH;, 
CH,.CH(NH,).COOH , on. CH COOu 
(paraoxyphenyl-a-amidopropionic (paraoxyphenylpropionic acid 
acid or tyrosine) or hydroparacumaric acid) 
yok (p) OH (p) 
20,1, SO 2CH,< +2C0, + 2H,0 
NCH,.CH,.COOH CH,,COOH 
(paraoxyphenylpropionic acid) (paraoxyphenylacetic acid) 


1 Arch. d. sc. biol., St. Pétersbourg, 1892, vol. i. p. 497. 

2 Ztschr. f. physiol. Chem., Strassburg, 1885, Bd. ix. S. 32. 

3 See Baumann. Ztschr. f. physiol. Chem., Strassburg, 1877-1880, Bd. i. S. 60 ; iv. S. 304; 
Ber. d. deutsch. chem. Gesellsch., Berlin, 1879, Bd. xii. S. 1450; 1880, Bd. xiii. S. 279 ; 
Baumann and Brieger, Zischr. f. physiol. Chem., Strassburg, 1879, Bd. iii. S. 149; E. 
and H. Salkowski, Ber. d. deutsch. chem. Geselisch., Berlin, 1879, Bd. xii. S. 648; E. 
Salkowski, Zschr. f. physiol. Chem., Strassburg, 1878-9, Bd. ii. S. 420; Weyl, did., 
1877-9, Bd. i. S. 339 ; iii. S. 312. 

4 For a description of the physical and chemical properties of these bodies, see 
Gamgee, ‘‘ Physiological Chemistry of the Animal Body,” 1893, vol. il. p. 434. 

° Baumann, Zschr. f. physiol. Chem., Strassburg, 1886, Bd. x. 8. 128. 

6 Ber. d. deutsch. chem.” Gresellsch., Berlin, 1879, Bd. xii. S. 1450. 


468 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


oH) oH.) 
CHC = C,H, HCO; 
CH,.COOH CH, 
(paraoxyphenylacetic (parakresol) 
acid) 
OH (p) ye 
2C HL +30,=2C,H,/ +2C0,+2H,0 
CH, NE 
(parakresol) (phenol) 


By a process of reduction, the oxy-acids probably yield the phenylpropionic 
and phenylacetic acids which have been found, thus :— 


OH (p) 
CHL 4+ 2H =C,H,.CH,.COOH + H,0 
\cu,.COOH 
(paraoxyphenylacetic (phenylacetie 
acid) acid) 


Aromatic bodies found in putrefaction not formed from tyrosine.—Indol, 
skatol, and skatolearbonic acid are not formed by bacterial action on tyrosine, 
and their mode of formation is not very clearly known. According to 
Baumann,! they are not primary products of bacterial action on the proteid 
molecule, but are formed in the decomposition of an intermediate body, which 
is soluble in a mixture of alcohol and ether. E. and H. Salkowski? support 
this conclusion. Nothing further is known of this intermediate substance, 
except that it is not peptone. Neumeister® considers it possible that these 
substances may be synthetically built up by the bacteria from simpler aromatic 
compounds. Indol and skatol are formed from this mother substance in 
varying proportion, probably due to the action of different bacteria, but these 
have never been isolated. 

Indol, skatol, and skatolearbonic acid belong to the indigo group of aromatic 
compounds. Indol on oxidation yields indoxyl, and on further oxidation, 
this yields indigo blue. By an inverse process of reduction from indigo blue, 
indol can be obtained. To indol and skatol the feces owe to a great extent 
their peculiar unpleasant odour. 


anes 
Indol,? C,H, CH, crystallises from water in small scales (M. P., 
Ey 


52° C., B. P., 245° — 246° C.). It is fairly soluble in hot, less so in cold water, 
and is easily soluble in alcohol, ether, chloroform, benzol, and petroleum ether. 
It distils over with steam; this property may be used to separate it from 
other putrefaction products. In long-continued putrefaction, indol gradually 
disappears ; according to Salkowski, this is due to evaporation. 

Indol may be recognised by the following tests :— 

1. A wooden match moistened with strong hydrochloric acid and then 
dipped into an alcoholic solution of indol turns a cherry-red colour. 


1 Ber. d. deutsch. chem. Gesellsch., Berlin, 1880, Bd. xiii. S. 284. 

* Zischr. f. physiol. Chem., Strassburg, 1884, Bd. viii. S. 454 ; see also Nencki and Bovet, 
Monatsh. f. Chem., Wien, 1889, Bd. x. S. 506. 

3 “Lehrbuch. d. physiol. Chem.,” Jena, 1893, Th. 1, S. 209. 

4 Nencki, Ber. d. deutsch. chem. Gesellsch., Berlin, 1875, Bd. viii. 8S. 722 ; Baumann, 
u. Brieger, Zischr. f. physiol. Chem., Strassburg, 1879, Bd. iii. S. 254. 

> Baeyer, Ann. d. Chem., Leipzig, Bd. ex]. S. 295; Supp. Bd. vii. 8. 56. 

®° For method of isolation from these, see Gamgee, ‘‘ Physiological Chemistry, etc.,” vol. ii. 
p. 421; or E. and H. Salkowski, Ztschr. f. physiol. Chem., Strassburg, 1884, Bd. viii. 8. 417. 


ACTION OF INTESTINAL BACTERIA ON PROTEIDS. 469 


2. An aqueous solution of indol treated with fuming nitric acid turns a 
bright red colour, and on standing a red precipitate is formed. 

3. When sodium nitroprusside is added to a very dilute solution of indol, 
and afterwards caustic soda, the mixture turns a deep violet-blue, passing into 
a pure blue on making faintly acid with acetic acid, and disappearing with 
excess of acid (Legal’s reaction).! 

NH 
Skatol,? C,H vs OH, is methyl-indol ; it crystallises in similar form 
\G.CH,7 


to indol (M. P., 95°C., B. P., 265° - 266° C.). It also possesses much the 
same solubilities as indol, and is volatile with steam. Passed through a red- 
hot tube, it decomposes and yields indol. 

It is distinguished, in addition to its physical properties, by the following 
tests :— 

1. Instead of a red precipitate, as in the case of indol, it gives a milky 
turbidity when treated with fuming nitric acid. 

2. In Legal’s test (vide supra) it gives an intense yellow, turning violet 
with acid. 

3. It dissolves in concentrated hydrochloric acid, giving a highly coloured 
solution. 

Both indol and skatol, dissolved in benzol in concentrated solution, give, 
with a saturated solution of picric acid in benzol, a crop of fine red crystals. 
When the compound of indol and picric acid is treated with caustic soda, and 
distilled, the indol is decomposed ; under similar conditions the skatol picric 
acid compound yields skatol which is not decomposed. 


,NH 


Skatol carbonic acid,? C,H, ‘SC-COOH, crystallises in scales (M. P., 
4 J 
ce NEC 


164° C.), sparingly soluble in water, easily soluble in alcohol and ether. Heated 
above its melting point, it breaks up into skatol and carbon-dioxide. 

It may be identified by the following tests :— 

1. Its aqueous solution, treated with pure nitric acid and afterwards with 
potassium nitrite solution, turns a cherry-red colour, and deposits a red pre- 
cipitate, which is dissolved by acetic ether. 

2. Its aqueous solution, treated with an equal volume of hydrochloric acid 
(sp. gr. 1:2), and afterwards with dilute bleaching powder solution, gradually 
turns a purple-red colour, and, after long standing, deposits a purple-red 
precipitate, easily soluble in alcohol. 

3. A very dilute solution (1 in 10,000 of water), treated with a few drops 
of hydrochloric acid, then with a few drops of a very dilute solution of ferric 
chloride, and heated, gives an intense violet colour. More concentrated solution 
gives an intense cherry-red colour. 

The aromatic compounds resulting from bacterial decomposition in the 
intestine are to a considerable extent absorbed. Tyrosine absorbed as such 
disappears ; it is decomposed and completely oxidised in the tissues without 
the formation of urea. The non-nitrogenous substances resulting from its de- 
composition by bacteria (as well as indol and skatol) are not completely 
oxidised, but are excreted in modified form in the urine, combined chiefly 
with sulphuric acid, as ethereal sulphates, but also in part with glycocoll and 
glycuronic acid. In this way the poisonous properties of the phenols and 
similar compounds are removed, for the ethereal sulphates formed are very 


1 Breslau. drztl. Zischr., 1893. 
2 Brieger, Ber. d. deutsch. chem. Gesellsch., Berlin, 1877, Bd. x. 8. 1028. 
3. and H. Salkowski, Ztsehr. f. physiol. Chem., Strassburg, 1885, Bd. ix. 8. 8. 


470 CHEMISTRY.OF THE DIGESTIVE PROCESSES. 


stable compounds, which are excreted unchanged ; thus phenol and kresol are 
eliminated as potassium salts of phenylsulphuric acid and kresolsulphuric 


OCH; yee gH4,—CH, 
acid respectively, SO, SO, 4 
ih Tate SOK 610.0" iw Home 


Indol and skatol are to a considerable extent excreted with the feces. 
The portion which is absorbed is first oxidised, yielding indoxyl and skatoxyl, 
and these are then united to form sulphates with potassium-hydrogen sulphate, 
thus :— 


af "Non on Nok onZ ON 
res | ve oH NH ifr 6 ag NH ee 
(indol) ae 1) (potassium indoxylsulphuric acid) 


The aromatic oxy-acids in part are found in the urine as simple salts, 
and in part combined with sulphuric acid. The simple aromatic acids (phenyl- 
acetic and phenylpropionic acids) are chiefly found united with glycocoll. 
The phenylpropionic acid is first changed into benzoic acid, and then unites with 
glyeocoll to form hippuric acid (benzoylglycocoll, Gils ‘CONH. CH,.COOH). 
The phenylacetic acid unites directly with elycocoll - to form phenaceturie 
acid (C,H;.CH,.CO—NH.CH,.COOH). 

Besides these substances belonging to the aromatic series, there are formed, 
during the putrefactive decomposition of proteids, a number of substances 
belonging to the fatty series. The chief of these are leucine, the ammonium 
salts of a number of volatile fatty acids (caproic, valerianic, and butyric), 
methane, hydrogen, sulphuretted hydrogen, and methylmercaptan (CH,.SH). 


Action of the intestinal bacteria on carbohydrates.—The carbo- 
hydrates suffer much more bacterial decomposition in the intestine 
than do the proteids. Not only are the sugars formed in digestion 
attacked, but starch is directly attacked by some bacteria, and 
cellulose, so far as it is decomposed, owes its changes to bacterial action. 
The products formed in such bacterial actions on the carbohydrates 
are simpler in their composition than those produced during putrefaction ; 
they consist chiefly of ethyl] alcohol, lactic (active and inactive), butyric, 
and succinic acids, accompanied by carbon-dioxide and hydrogen. 

Nencki, Macfadyen, and Sieber? isolated seven different intestinal 
bacilli, of which five acted only on carbohydrates (dextrose), and the 
other two mainly on proteids. 

Cellulose is altogether unattacked by any of the digestive juices im 
vitro; nevertheless it disappears to a very considerable extent in natural 
digestion. Experiments on herbivora show that 60 to 70 per cent. of 
the cellulose disappears,* and even shavings and paper mixed with hay 
and given to sheep only partially reappear in the feces. Experiments 
on man show that, according to the condition and form of the cellulose, 
amounts varying from 4 to 60 per cent. are digested.* 

Of the manner in which this cellulose is broken up or dissolved we 
know nothing with certainty. Bunge® supposes that the epithelial cells 


1 Wortman, Zétschr. f. physiol. Chem., Strassburg, 1882, Bd. vi. S. 293 ; Lander Brunton 

and | Macfadyen, Proc. Roy. Soc. London, 1889, vol. “xlvi. p. 542. 
2 Arch. f. exper. Path. wu. Pharmakol. , Leipzig, 1891, Bd. xxviii. S. 311. Reprinted in 

Journ. Anat. and Physiol., London, 1891, vol. xxv. p. 390. 

3 Haubner, Zischr. f. Landwirthschaft, 1885, S. 177. 

4 Weiske, Zischr. f. Biol., Miinchen, 1870, Bd. vi. S. 456; v. Knieriem, ibid., 1885, 
Bd. xxi. S. 67. 

° “*Tehrbuch der physiol. u. path. Chem.,” 1894, S. 174, 


ACTION OF INTESTINAL BACTERIA ON FATS. 471 


of the intestine possess the function, by means of a ferment, of dissolving 
the cellulose; this may be so, but no such ferment has ever been shown 
to exist. Bunge supports his suggestion by analogy with the action 
of some unicellular organisms on cellulose.! 

Exposed to the action of certain organisms, cellulose undergoes 
fermentation with the setting free of marsh gas (CH,), and the forma- 
tion of acetic and butyric acids; how much of the altered cellulose goes 
in this way in the digestive process is unknown. ‘Tappeiner? tested 
the action of the intestinal bacilli on cotton-wool, by soaking this in a 
1 per cent. solution of bouillon and inoculating with’ the bacilli. Fer- 
mentation with development of gas commenced, and there were formed 
in the solution free fatty acids (up to and including valerianic acid), 
while the cotton-wool nearly all dissolved. The gases set free were 
marsh gas and carbon-dioxide. The nature of the products varies with 
the organism acting on the cellulose; thus Hoppe-Seyler* obtained the 
same gases accompanied by a dextrin-like substance, by the action of 
pond bacteria on cellulose in the form of filter paper, but did not observe 
the formation of any fatty acids. 

Experiments on the artificial digestion of cellulose in the form of 
new hay were made by Hofmeister who showed that the intestinal 
juices of the horse were capable of dissolving nearly 80 per cent. of this 
material. No formation of sugar but some fermentation and develop- 
ment of gas were observed. 

The most important uses of cellulose le, however, not in its value 
as a nutrient foodstuff, but in giving bulk and looseness to the food and 
in mechanically inducing peristalsis by irritation of the intestine.2 For 
this reason cellulose becomes an absolute necessity for animals with a 
long intestine, such as the herbivora. Rabbits fed on food free from 
cellulose rapidly die from intestinal inflammation; but if the same food 
be mixed with such an inert substance as horn shavings, nutrition goes 
on quite normally, and the animals continue in perfect health, although 
the horn shavings remain entirely unaltered. The carnivora with their 
short intestine require no such aid to peristalsis; but in animals in an 
intermediate position, such as man, bulky or cellulose-containing food, 
while not indispensable, is from a dietetic point of view exceedingly 
desirable. 

Action of the intestinal bacteria on fats.—Under a normal con- 
dition of the intestine, it is probable that very little decomposition of 
the fats by bacteria takes place, but under abnormal conditions, such 
as the absence of the bile or pancreatic Juice, they are almost completely 
decomposed into fatty acids, which pass out unabsorbed along with the 
feeces. The first action of bacteria on fats consists in setting free the 
corresponding fatty acids; these are afterwards partially broken down 
into mixtures of fatty acids lower in the series.7 

Lecithins undergo a similar decomposition by bacteria under anie- 
robic conditions; they at first are split up into glycerophosphoric acid, 
fatty acids, and choline. Afterwards, the choline is decomposed with 


1 £.g., Vampyrella; Cienkowski, Arch. f. mikr. Anat., Bonn, 1865, Bd. i. S. 203. 
2 Zischr. f. Biol., Miinchen, 1884, Bd. xx. 8. 52; ibid., 1888, Bd. xxiv. S. 1085. 

3 Ztschr. f. physiol. Chem., ’Strassburg, 1886, Bd. x. S. 401. 

4 Arch. f. wissensch. u. prakt. Thierh., Berlin, 1885, Bd. xi. S. 46. 

> Bunge, ‘‘ Physiological and Pathological Chemistry,” 1894, p. 75. 

By. Knieriem, Ztsehr. f. Biol., Miinchen, 1885, Bd. xxi. S. 67. 

7 Groger, Ztschr. f. ang. Chem., Berlin, 1889, S. 62. 


472 CHEMISTRY OF THE DIGESTIVE PROCESSES. 


formation of carbon-dioxide, methane, and ammonia; but if air is present, 
neurin and muscarin are also formed in the process.t 


COMPOSITION OF FAECES. 


Amount and consistency—The consistency of the contents of the 
small intestine in the upper two-thirds to three-fourths of its length 
is fairly uniform, the amount of water absorbed in this part being 
approximately balanced by that added in the digestive fluids. But 
in the lower part of the small intestine the amount of water absorbed 
begins to exceed that secreted; the intestinal contents become 
thicker, and the thin fluid, with lumps of solid, undigested, or 
partially digested food of various kinds floating in it, which is usually 
found in the higher part of the intestine, is replaced by a pasty 
or semi-solid mass. As this mass passes along the large intestine the 
process of absorption continues with increased intensity, and a large 
amount of water, together with anything it holds in solution of service 
to the economy, is removed. The residue, a complex mixture of various 
useless or unused material, usually acquires the consistency of a soft 
solid before the completion of the process, and is finally ejected from the 
rectum. The consistency of the feces, as well as the amount excreted 
per diem, varies within wide limits, with the character of the food 
and the duration of its passage through the intestine. Even in the 
rectum the process of absorption goes on, and feces retained here become 
dry and hard. The feces passed on a vegetable diet, or on a diet con- 
taining a liberal allowance of vegetables, are both much softer (4. 
contain more water) and much greater in total quantity of dry solids 
than those on a meat diet alone. The increase in the quantity of solids 
is due to the vegetable food containing a much higher percentage of 
undigestible tissue. The softer consistency arises from the stimulation of 
the mucous membrane by the undigested remnants of the vegetable 
tissue, causing increased peristalsis, so hastening the transit through the 
intestine, and shortening the period of absorption. This stimulating 
action of vegetable food adds greatly to its value in a mixed diet. In 
consequence of the absence of this stimulus, the period of defeecation 
is greatly prolonged on a purely flesh diet, and may only take place 
at intervals of several days. The amount of feeces daily excreted by 
man on a mixed diet averages, according to Voit,? 120 to 150 grms., 
containing 30-37 germs. of dried solids; on a vegetarian diet, the 
average amount obtained was 333 grms., containing 75 grms. of dry 
material. 

Colour.—The colour of the feces varies greatly, being mainly influ- 
enced by the nature of the food. On a diet of meat, the colour is dark 
brown to pitch black, due to hematin and to ferrous sulphide, formed 
by the action on hzmoglobin-derivatives, of sulphuretted hydrogen 
generated by bacteria in the intestine. Administration of iron or 
bismuth salts produces a similar effect. A liberal allowance of bread, 
especially of the coarser varieties, in the food, gives rise to light yellow- 
coloured feces. Fat, when eaten in greater quantity than the animal 
requires, is excreted with the feeces chiefly as fatty acids and soaps, and 


1 Hasebrock, Ztschr. f. physiol. Chem., Strassburg, 1888, Bd. xii, S. 148, 
2 Zischr. f. Biol., Miinchen, 1889, Bd. xxv. S. 264, 


—— > 


COMPOSITION OF FACES. 473 


causes the feces to have a yellowish or clay-coloured appearance. 
Such fatty stools also result when imperfect fat absorption is caused by 
stoppage of the bile duct. The derivatives of bile pigments also con- 
tribute to the colour of the feces, and part of the brown colour of 
normal feces arises from these, although it is probably due in greater 
measure to hematin. Administration of calomel, by arresting bacterial 
decomposition, prevents the reduction of the bile pigment, which then 
appears in the fieces as biliverdin, and produces a green colour. The 
similar colour of meconium shows that bacteria are absent in the fetal 
intestine. Green-coloured feces are also excreted for some time after 
birth, until the normal bacteria of the intestine gradually acquire 
possession, when the biliverdin is reduced and the feces assume a brown 
colour. 

Reaction —The reaction of the feces is also variable. According to 
Hammarsten,? they may often be alkaline on the surface, from contact 
with the intestinal mucous membrane, while acid within the mass. 
Gamgee® states that the feces in man are normally alkaline, and very 
exceptionally present an acid reaction. Wegscheider* found the feces 
normally acid in infants. 

Composition.—The feces are an exceedingly complex mixture, con- 
taining substances of various origin and constitution, soluble and 
insoluble, derived from the food, the bile, and the detritus of the in- 
testinal surface.2 The number of these components is so large, and the 
amounts in which they are present so variable, that tables of quantitative 
composition possess little value. 

The undissolved substances consist of fragments of undigested food, 
such as pieces of vegetables, muscle fibres, connective tissue, elastic 
fibres, and small masses of casein and fat. The amount of these is 
largely increased when the supply of food taken in is more than 
sufficient to satisfy the demands of the body. A microscopic examina- 
tion further shows epithelial cells derived from the intestine, starch 
granules, fat globules, and occasionally crystals of magnesium and 
calcium phosphates, and of ammonia-magnesium phosphate. Besides 
these, there is present the indigestible residue of various foodstuffs, 
such as nucleins from nucleo-proteids, keratin from epidermal struc- 
tures, and hematin from hemoglobin. 

The mineral salts present vary with the food, but consist chiefly of 
the phosphates of the alkaline earths, with small quantities of silica and 
phosphate of iron. 

The other constituents include mucin, derived from the various 
secretions, mainly from the mucous membrane of the intestine; indol, 
skatol, volatile fatty acids, ammonia, sulphuretted hydrogen, and methane, 


1 There is some difference of opinion on this point. Gamgee (‘‘ Physiological Chemistry of 
the Animal Body,” vol. ii. p. 458) states that the brown colour of normal feces is due to 
hydrobilirubin ; Hammarsten (‘‘ Lehrbuch der physiol. Chemie,” Aufl. 3, S. 283), that the 
decomposition products of the bile pigments have little influence on the normal colour of 
the feces. 

2 «<Tehrbuch der physiol. Chemie,” Aufl. 3, S. 284. 

8 «* Physiological Chemistry of the Animal Body,” vol. ii. p. 457. 

+ Jahresb. ti. d. Fortschr. d. Thier-Chem., Wiesbaden, 1876, Bd. vi. 8S. 482. 

5 The mucous membrane of the intestine and its secretion furnish a considerable quota 
to the fieces ; this is shown by an experiment due to Hermann (Arch. /. d. ges. Physiol., 
Bonn, 1890, Bd. xlvi. S. 93), who separated a loop of intestine, cleared it of contents, sewed 
its two ends together so that it formed a ring, restored the continuity of the remainder of 
the intestine, and closed the wound. In a few days it was found, on killing the animal, 
that this loop was filled with a mass resembling feces in appearance, 


474 CHEMISTRY OF THE DIGESTIVE PROCESSES: 


which are formed in bacterial decomposition ;! and the products yielded 
by the bile, stercobilin, cholesterin, and traces of bile acids.? 

Stercobilin® is a reduction compound of the bile pigments formed 
in their passage along the intestine, and is probably identical with 
urobilin and hydrobilirubin. Normally, all the bile pigment is reduced 
to this substance, but bilirubin has been observed in the feces under 
pathological conditions. 

Hxeretine is a crystalline body, described by Marcet* as occurring 
only in human feces. It is very soluble in boiling alcohol, and may be 
mechanically thrown down from an alcoholic extract of the faeces by 
adding milk of lime. The precipitate is washed with water, dried and 
extracted with a mixture of alcohol and ether. On concentration of the 
solution by evaporation, impure excretine crystallises out. This is 
dissolved in hot alcohol, decolorised by animal charcoal, and obtained 
pure on recrystallisation in acicular four-sided prisms, melting at 92°— 
96°C. It is insoluble in water, hot or cold; sparingly soluble in cold, 
readily in hot alcohol; very soluble in ether ; and the solutions are 
neutral in reaction. Its quantitative composition gives the formula 
C.,H,;,,50,. Hinterberger® states that, by repeated crystallisation, it may 
be obtained free from sulphur, and then has the empirical formula 
C,,H,,0; with bromine this yields a substitution compound, C,,H,,Br,0. 

Excretoleic acid is a body described by Marcet,’ who obtained it on 
cooling a hot alcoholic solution of human feces. On exhausting with 
ether, a green ethereal solution is obtained, which, on evaporation, leaves 
an oily residue of a dark green colour and acid reaction, melting at 

O52 IGG 

Meconium is the name given to the contents of the large intestine in 
the foetus, which are expelled at, or after, birth. It is a dark brownish- 
green mass of acid reaction. It contains 20 to 30 per cent. of dried 
solids, which consist of mucin, bile pigments (biliverdin and bilirubin), 
bile acids, cholesterin, fats, fatty acids, calcium and magnesium phos- 
phates and sulphates. 

In addition it contains a substance giving two absorption bands, one 


to the red side of the D line, and the other, broader and darker, between 
the D and E lines. 


1 The odour of the feces arises from these bodies. 2 See p. 391. 

3 Vanlair and Masius, Centralbl. f. d. med. Wissensch., Berlin, 1871, No. 24, S. 369; 
see also under “ Bile,” p. 388. 

+ Med. Times and Gaz., London, 1858, N. S., vol. xvii. p. 156. 

> Ann. d. Chem., Leipzig, 1873, Bd. elxvi. S. 213. § Loc. cit. 


THE SALIVARY GLANDS.! 


By J. N. LANGLEY. 


Contents :—Anatomical Characters, p. 475—Histological Characters, p. 477—Origin 
and Course of Nerves, p. 479—Changes during Secretion, p. 485—Reflex Secre- 
tion, p. 489—The Dyspneie Secretion, p. 493—Stimulation of the Cranial 
Nerve, p. 493—Stimulation of the Sympathetic Nerve ; the Augmented Secre- 
tion, p. 494—Effect of Protracted Stimulation on the Amount and Percentage 
Composition of Saliva, p. 498—Relation of the Rate of Secretion to the Per- 
centage Composition of Saliva, p. 499—Some General Characters of Saliva, p. 501 
—Substances secreted in Saliva, p. 503—Effects of the Cranial and Sympathetic 
Nerves upon the Blood Flow, p. 504—Mutual Effects of the Cranial and Sym- 
pathetic Nerves upon Secretion, p. 506—Effect of Variations in the Amount 
and Quality of the Blood supplied to a Gland, p. 508—Relation of Secretion to 
the Flow of Lymph, p. 510—The Secretory Pressure, p. 511—Reflex Inhibition 
of Saliva, p. 512—The Action of Alkaloids, p. 512—Formation of Heat, p. 516 
—Electrical Changes, p. 517—Section of Glandular Nerves; the Paralytic 
Secretion, p. 519—NSecretion due to Reflex Action of Peripheral Ganglia, p. 523 
—Direct Irritability of Gland-Cells, p. 524—Extirpation of the Glands ; injec- 
tion into the Blood of Saliva and of Gland Extracts, p. 524—General Con- 
siderations ; theories of the Mode of Action of Secretory Nerves, p. 525. 


Some ANATOMICAL CHARACTERS OF THE SALIVARY GLANDS. 


In the dog and cat, the sublingual gland enlarges at its end, and 
loses its flattened form; the enlarged end is closely attached to the sub- 
maxillary gland, and is enclosed in the firm capsule of this gland, so that 
at first sight it appears to form part of it. 

The ducts from the lobules of the submaxillary gland unite, either 
in the connective tissue which stretches from the hilus of the gland, or 
in the hilus itself. The gland duct—the duct of Wharton—runs from 
the hilus to its opening underneath the tongue, without receiving, except 
in rare cases, any further accession. 

The sublingual gland in about its anterior two-thirds consists of 
flattened lobules, the ducts of which enter the main duct on its course 


1 Physiological investigations on the salivary glands have, for the most part, been 
carried out on the larger glands, namely, the submaxillary, the parotid, and the sublingual. 
But such conclusions as we may be able to form with regard to these, we may apply with 
little change to the numerous smaller glands which pour their secretion into the mouth 
and pharynx, and, indeed, to the lachrymal glands and glands of the nasal mucous mem- 
brane also. Both in histological and physiological characters the lachrymal gland 
resembles an albuminous salivary gland. It receives cranial secretory fibres by way of the 
lachrymal branch of the fifth nerve; the origin of these fibres from. the medulla has not 
been investigated. It receives sympathetic fibres by way of the cervical sympathetic and 
the blood vessels of the gland. Secretion can be produced reflexly by stimulating most, 
if not all, sensory nerves. 

The animals on which investigations have been made are chiefly the dog, cat, and rabbit, 
the horse, ox, and sheep. 


476 THE SALIVARY GLANDS. 


past them. Thus the gland has no proper hilus. The duct runs parallel 
to and a little laterally of Wharton’s duct. 

The main blood supply, both to the submaxillary and the sublingual 
gland, is derived from a branch given off by the external maxillary 
artery. The submaxillary division of this branch runs to the hilus of 
the gland, and there divides. The submaxillary gland receives also one 
or two small branches from the great (or posterior) auricular artery, 
where this curls round the digastric muscle. 

The veins of the submaxillary gland are variable in position, and 
somewhat variable in number. There are generally two; they run a 
short course, about half a centimetre, and then one enters the internal, 
and the other the external, maxillary vein, a little before these unite to 
form the external jugular vein. 

In the dog and eat there is a fairly large gland situated in the orbit, 
and hence called the orbital gland. Its “duet opens near the second 
upper molar tooth. The orbital gland corresponds to the large buccal 
gland, which in some animals is called the superior molar. 

In the rabbit, the only point we need mention is that the parotid 
gland consists of two larger and thicker portions, a medial and a lateral, 
connected by a thin central portion. By appropriate arrangement, the 
thin central portion can be observed under a microscope, and the appear- 
ance of the gland cells in life, and the variations of the blood flow in 
varying conditions, can be observed. 

Occasionally i in the dog, and more constantly in some other animals, 
for instance the cuinea-pig, a small gland, called by Klein? the inferior 
admaxillary, pours its secretion into the duct of the parotid. It 
may be regarded as a separated lobule of the parotid gland, although 
its secretory cells are mucous, instead of beimg albuminous, thus 
differing from the parotid secretory cells in general (cf. below, p. 4778), 

In a considerable number of animals, a small mucous gland is 
attached to the outer anterior end of the submaxillary gland. This 
was described by Klein in the guinea-pig, and called by him the superior 
admaxillary. The duct of this gland, according to Ranvier, runs parallel 
to and on the outer side of Wharton’s duct, but does not join it. He 

calls it the retrolingual gland. 


Ranvier? considers that the customary use of the term sublingual gland is 
in many cases erroneous. The sublingual, he defines as a gland which has a 
number of separate ducts—the ducts of Rivini. But, besides the sublingual, 
another gland occurs, which he calls the retrolingual gland. This is charac- 
terised by having a single duct—the duct c rttholi ing parallel to 
Wharton’s duct. An animal may have both sublingual and retrolingual, as 
the guinea-pig, rat, and hedgehog ; or the retrolingual may be absent, as in 
man, horse, sheep, ‘and rabbit ; or, again, the sublingual may be absent, as in 
the dog and cat. Thus Ranvi ier considers the gland usually called the sub- 
lingual in the dog and cat to be the retrolingual. 


In different classes of mammals, the relative development of the 
salivary glands varies. Thus in the horse the parotid is four to five times 
the weight of the submaxillary gland, in the sheep and ox the weights 
are not. very different, in the dog the submaxillary gland is slightly 
heavier than the parotid. 


1 Quart. Journ. Micr. Sc., London, 1881, p. 114. 


9 


* “Etude anatomique des glands,” Arch. de physiol. norm. et path., Paris, 1886. 


HISTOLOGICAL CHARACTERS. 477 


The following table is taken from Colin : '— ° 


| Weight in Grammes of > Parotid. | Submaxillary. Sublingual. 
| a 
Horse. : : , 400 | 86 23 
Ceapeeiint 2 eqeulit MERE ap Mabini 2980). 9{ 43 
Sheep. : : | 43 36 | 4 


SoME HISTOLOGICAL CHARACTERS OF THE SALIVARY GLANDS. 


It would be outside the scope of this account to give a detailed 
description of the ducts, ductules, terminal tubes, lymphatics, and other 
histological features of the several glands. But some of the histological 
features have so intimate a relation to physiological observations, that it 
is not advisable to pass them by without notice. 

The narrow ductule, proceeding from a duct, commonly divides, and 
each secondary ductule widens more or less suddenly into a tube of 
secreting cells; each tube gives off curved branches, and these also may 
give off similar branches; thus, a clump of tubes is formed around the 
primary ductule. The terminal tubes are usually called alveoli, and their 
. cells alveolar cells. 

The alveolar cells may be classified according to the chemical nature 
of the substances they secrete. A step in this direction was taken by 
Heidenhain, who divided the cells into mucous cells which secrete mucin, 
and albuminous cells which secrete some form of proteid. There is good 
evidence that the typical albuminous cell does not secrete any mucin, 
and there is some evidence that the typical mucous cell does not secrete 
any proteid, and on this basis it is apt to be assumed that all the alveolar 
cells secrete either mucin only, or proteid only. It should, however, be 
remembered that this is an assumption ; it is possible that some alveolar 
cells secrete both mucin and proteid. 

In any one salivary gland all the alveolar cells may be mucous or 
all may be albuminous, or some of them may be mucous and some 
albuminous. Further, in different glands, the relative number of the 
two kinds of cells varies in nearly all possible proportions. The 
nomenclature in use takes notice of the broad distinctions only. Glands 
which consist almost entirely of albuminous cells are called albuminous 
glands, those which consist chiefly of mucous cells are called mucous 
glands. The glands of intermediate structure are commonly placed 
in the class of mucous glands, unless the proportion of mucous to 
albuminous cells is very small. 


The term “mixed gland” was introduced for certain special cases; for example, 
the submaxillary gland of the guinea-pig, in which one or more lobules were 
said to be mucous and the rest to be albuminous. But in the guinea-pig, and 
possibly in the other cases, the mucous lobule appears to be a separate gland 
(cf. above, p. 476). It would probably be more convenient to use the term 
“mixed,” for a gland in which the mucous and albuminous cells are present 
in approximately equal proportions. And we might have the following scale, 
passing from entirely albuminous to entirely mucous :—albuminous glands, 


1 ““Traité de physiol. comparée des animaux,” 8rd edition, 1886, tome i. 


478 THE SALIVARY GLANDS. 


muco-albuminous glands, mixed glands, albumino-mucous glands, demilune 
glands, mucous glands. 


The demilune cells, there ean be little doubt, are albuminous 
secretory cells. If we compare a series of submaxillary glands, passing 
from albuminous to mucous, we find that the albuminous cells become 
more and more confined to the ends of the terminal tubes, and the fewer 
there are the more compressed they become by the mucous cells, a 
feature, however, which is more marked in hardened than in fresh 
glands. And when the gland secretes, the demilune cells show obvious 
signs of secretory activity. The small discrete granules in them 
diminish in number, and in some animals form an inner granular zone ; 
in alcohol-hardened glands, the demilune cells stain more deeply with 
carmine, and the nuclei and nucleoli are more conspicuous. The cells 
diminish in size after prolonged activity of the gland. In the earlier 
stages of secretion they appear to be larger, but this is probably due to 
a diminution in the size of the mucous cells, and so of the whole tube, 
whereby the demilune cells are less flattened. 

A comparison of the large salivary glands in different mammals 
shows that the parotid has least variation in structure, and the sub- 
maxillary gland the most. 

The parotid gland, as a rule, contains albuminous cells only; but 
in the dog there are commonly, if not always, a few mucous cells, 
or mucous alveoli present. And there may be in the dog a small 
mucous lobule, pouring its secretion into the duct a short distance from 
the main gland. 

The submaxillary glands are entirely albuminous in rodents. In 
primates, the majority of the cells are albuminous, but some are mucous. 
In solipedes and ruminants, the glands are “mixed,” but most of the 
cells are mucous. In carnivora the great majority of the alveolar cells 
are mucous, but some are albuminous, and there are fewer albuminous 
cells in the submaxillary gland of the dog than im that of the cat; 
thus in a microscopical preparation of the gland of a dog, the albuminous 
cells are almost entirely in the form of demilunes, whilst in a similar 
preparation of the gland of a cat, a considerable number of albuminous 
alveoli are seen. In the mole, large portions of the submaxillary gland 
do not even contain demilunes, and in these portions none but typical 
mucous cells occur. 

The sublingual gland in all animals contains a greater or less 
proportion of mucous cells, and it is in consequence generally called 
a mucous gland. But as it always contains albuminous cells also 
it belongs properly to the class of mixed glands. The sublingual gland 
has certain characters which distinguish it from the submaxillary gland. 
It is more obviously tubular, the lumina are often large, the cells in a 
section of a hardened specimen are more columnar, and a considerable 
number of them consist, in their ordinary resting state, of proteid 
material in the outer third, half, or even two-thirds, and of mucous 
material in the remaining portion next the lumen. 


The orbital gland? of the dog is mucous, the mucous cells are large and 
contain very little proteid substance, the demilunes are much flattened. The 


1Langley, Trans. Internat. Med. Cong., 1880; Proc. Roy. Soc. London, vol. xi. p. 
364 ; and this view has been taken by most subsequent observers. 
2 Cf. Lavdowsky, Arch. f. mikr. Anat., Bonn, 1877, Bd. xiii. p. 288. 


“a 


ORIGIN AND COURSE OF NERVES. 479 


admaxillary glands (Klein) have been found, so far as they have been 
investigated, to be mucous glands. 


One or two points with regard to the structure of the alveolar cells, 
which bear upon questions we have to consider later, we may also 
mention. 

In all salivary alveolar cells there are found, though with very 
different degrees of distinctness, more or less spherical granules, destined 
in an altered or unaltered condition to become part ‘of the secretion. 
Whether the cell substance, in which the granules are embedded, has 
or has not a definite structure, we cannot decide with certainty; this 
cell substance may be what we speak of as granular structureless 
protoplasm ; or it may consist of two parts,—a protoplasmic part form- 
ing externally a boundary layer, except perhaps towards the lumen, 
and internally a delicate network ; and another part between the net- 
work and the granules, which in some cells may be of an albuminous 
and in others of a mucous nature. 


Every gland has its own distinctive histological features, implying a 
distinctive chemical character in the substance it secretes. In addition, 
secreting cells of obviously different nature often occur in the same gland. 
Thus, in the submaxillary gland of the rat, there is an ordinary albuminous 
portion, and running through this are tubes, in bold curves, consisting of cells 
with large granules, which sometimes leave an outer clear zone. And in the 
submaxillary gland of the rabbit, the first cells of the alveoli, and the terminal 
ductules, have in the fresh state conspicuous granules, differing widely from 
the faint granules of the rest of the cells in the ‘alveoli. 


ORIGIN AND COURSE OF THE NERVES TO THE SALIVARY GLANDS. 


All the salivary glands are supphed with nerve-fibres from two 
sources. They receive nerve-fibres, on the one hand, from the medulla 
oblongata, by way of some cranial nerve; and, on the other hand, from 
the spinal cord, by way of the cervical sympathetic. 

The cranial nerve contains many, the sympathetic nerve comparat- 
ively few, secretory fibres. The cranial nerve contains vaso-dilator, 
and the sympathetic nerve contains vaso-constrictor fibres for the small 
arteries of the glands. There is, at present, no evidence worth con- 
sidering that the cranial nerves have vaso-constrictor fibres for the 
glands, or that the sympathetic nerve has vaso-dilator fibres for them. 

The chorda tympani and the nerve-cells with which it is 
connected.—The submaxillary, the sublingual glands, and the glands 
of the tongue, receive secretory ‘and vaso- -dilator ‘fibres from the chorda 
tympani. "The chorda tympani arises from the seventh nerve; it leaves 
this in the Fallopian canal, runs across the tympanum, and joins the 
lingual branch of the third division of the fifth nerve. The nerve thus 
formed may be called the chordo-lingual ; it extends roughly up to the 
dorsal edge of the sublingual gland; here nearly all the fibres for the 
submaxillary gland, and ‘about half. of those for the sublingual gland, 
leave the lingual fibres, generally in four or five delicate strands, ‘lying 
close together. These strands, with the tissue around: them, are easily 
dissected out as a single bundle, and the bundle of nerve strands is 
called the chorda tympani, although it is a part only of the chorda 
tympani proper. The chorda tympani curves backwards towards the 


480 THE SALIVARY GLANDS. 


gland ducts, and accompanies them into the glands. Other fine 
filaments, coming from the chorda tympani proper, are given off from 
both sides of the lingual, as it runs forward over the sublingual 
gland; most of these end in this gland, but a few fibres, varying in 
number in different animals, run back and supply the submaxillary 
gland. Finally, a few fibres, from the chorda tympani proper, con- 
tinue their course in the lingual, and supply the glands and blood 
vessels in the area of distribution of the lingual nerve in the tongue. 

On the course of the nerve filaments to the glands are a number 
of small and often microscopic ganglia. In the smaller filaments these 
begin a very short distance from the lingual nerve, and then occur at 
intervals as far as the terminations of the ducts. Fibres from the 
filaments and ganglia intermingle, and form a plexus; this plexus, at 
first, overlies the sublingual gland, but, further on, surrounds and 
accompanies the ducts, chiefly those of the sublingual gland. The 
larger part of the chorda tympani passes by this plexus, and runs 
direct to a ganglion in the hilus of the submaxillary gland; where the 
duct begins to divide, this ganglion gives off strands, which form 
another plexus, surrounding and accompanying the divisions of Whar- 
ton’s duct. 

Some of the ganglia in the plexus over the sublingual gland are 
relatively large; thus in the dog there is, as a rule, a ganglion, which 
may be seen with the eye, in the angle between the lingual and 
the chorda tympani. This was called, by Bernard, the submaxillary 
ganglion; as we shall see presently, it is more appropriate to call it 
the sublingual ganglion. Another, and a larger ganglion, is that 
spoken of above, as present in the submaxillary gland. As this belongs 
chiefly, if not entirely, to the submaxillary gland, we may call it the 
submaxillary ganglion. But it must be remembered that the nerve- 
cells which occur on the course of the chorda tympani fibres, either to 
the sublingual or to the submaxillary gland, are not collected together 
in a single ganglion, but occur scattered at intervals on the nerve- 
plexus into which the fibres run. 

The nerve-cells are on the course, both of the secretory and of the 
vaso-dilator fibres of the chorda tympani. This may be shown by 
stimulating the chorda tympani, centrally of the nerve-cells, and 
peripherally of them, before and after injecting nicotine into a vein.t 
The experiment is best made in a cat. Normally, stimulation of the 
chorda tympani, in any part of its course, causes a flow of saliva, and an 
increased blood flow from the gland vein. After injecting a small dose 
of nicotine into a vein (cf. p. 515), stimulation of the chorda tympani in 
the tympanic cavity, or of the chordo-lingual nerve, has no effect. But 
a rapid secretion, and a greatly increased blood flow from the gland vein 
—in fact, the usual effects of stimulating the chorda tympani—are 
readily obtained by stimulating the nerve plexus in the hilus of the 
gland. Since no nerve except the chorda tympani is able to produce 
these effects, we may safely conclude that, in stimulating the nerve- 
plexus in the hilus of the gland, it is the peripheral chorda tympani 
fibres which cause the secretion and increased blood flow. The amount 
of nicotine given does not prevent—nor, so far as we know, affect—the 
passage of a nervous impulse along a nerve-fibre, and, in consequence, 
we conclude that the nerve-cells are on the course of the chorda 


1 Langley, Journ. Physiol., Cambridge and London, 1890, vol. xi. p. 123. 


THE CHORDA TYMPANI AND NERVE-CELLS. 481 


tympani fibres, and that nicotine either acts on the connection of the 
nerve-fibres with the nerve-cells, so that a nervous impulse cannot pass 
from one to the other, or acts on and paralyses the cells. The former is 
the more likely, and, in accordance with what is known generally 
regarding the relations of different nerve units, we may suppose that 
the nerve-fibres divide into fibrils, which terminate on the nerve-cells, 
and that these terminations are paralysed by nicotine. 

I have only spoken, so far, of the effect, after nicotine injection, of 
stimulating the chordo-lingual and the plexus in the hilus of the gland. 
If the stimulus be applied between these two places, the effect varies in 
different cases, and varies also in different animals. Broadly speaking, 
as the electrodes are passed along the chorda tympani and nerve- 
plexus, towards the hilus, a point will be found where the stimulus 
causes a slight secretion ; as the electrodes are passed more peripherally, 
the secretion increases, but it is rarely considerable, until the hilus of 
the gland is reached. This means that a few of the nerve-cells, 
outside the submaxillary gland, send their axis-cylinder processes to 
the gland. It may be mentioned that the relative number of these 
is greater in the rabbit than in the cat, and greater in the cat than 
in the dog. 

Similar conclusions as to the relation of the fibres of the chorda 
tympani to the peripheral nerve-cells may be deduced from the experi- 
ments in which the chorda tympani has been cut, and time allowed for 
its fibres to degenerate. I shall deal later with these experiments 
(p. 519); and it will be sufficient to give here the chief result which 
bears on the question before us. When the chorda tympani, or the 
chordo-lingual nerve, is cut in a dog or cat, and the peripheral cut end, 
after about four days, is stimulated, no effect is produced; but if a little 
pilocarpine be injected, a fairly copious secretion is obtained, and the 
blood flow through the gland is increased. Although it is not agreed on 
all sides that pilocarpine produces a secretion by stimulating the nerve- 
endings in the glands, this is probably the case, and if it be so, the 
experiment shows that the chorda tympani fibres have degenerated up 
to the peripheral nerve-cells, whilst the fibres given off by the nerve- 
cells are still intact. 

The position of the nerve-cells on the course of the chorda tympani 
fibres to the sublingual gland can similarly be determined. If a 
sufficient dose of nicotine be given to a dog, stimulation of the chordo- 
lingual nerve has no effect ; stimulation of the ganglionic nerve-plexus, 
lying in the angle between the chorda tympani and the lingual nerve, 
causes constantly some secretion from the sublingual gland, but none, as 
a rule, from the submaxillary gland. The ganglion, called by Bernard 
the “submaxillary ” ganglion, is the chief ganglion of this plexus; it 
follows, from what has just been said, that, at least in the dog, this 
ganglion sends fibres to the sublingual gland, but commonly sends no 
fibres to the submaxillary gland. It is, then, more accurate to speak of 
it as the sublingual ganglion. 

It is well known that there are small groups of nerve-cells in the tongue 
itself ; these, for the most part, are probably on the course of the chorda 


tympani fibres to the glands, and to the small arteries of the tongue, but there 
is no experimental evidence on the point. 


The fibres of the chorda tympani pass through the geniculate 
VOL, I.—31 


482 THE SALIVARY GLANDS. 


ganglion, but it is probable on general grounds that they are not con- 
nected with the nerve-cells of this ganglion. 

The nerve-strands which leave the chordo-lingual and the lingual 
nerve to run to the sublingual and submaxillary plexuses consist in 
very large part of small fibres, about 2 % to 3° w in diameter,! but a few 
larger up to 8 or 10 w are also present. In the plexuses the number of 
medullated fibres decreases, and the number of non-medullated fibres 
increases in passing towards the periphery. The axis-cylinder pro- 
cesses, then, of most, if not of all, the peripheral nerve-cells are non- 
medullated fibres. 

The large nerve-fibres may occasionally be seen to divide. They are 
probably sensory fibres for the gland arising from the fifth nerve. Some 
of the small fibres may also be sensory. 

Cranial nerve-fibres to the parotid and orbital glands.—The 
course of the secretory and vaso-dilator fibres to the parotid gland varies 
in different animals. 

In the dog they arise from the ninth nerve ; they ram—as Jacobson’s 
nerve—across the tympanic cavity over the promontorium forming part 
of the tympanic plexus. From the tympanic cavity they proceed to the 
small superficial petrosal and otic ganglion, and thence to the auriculo- 
temporal branch of the fifth nerve, and so to the parotid gland. 

In the sheep and ox the origin of the secretory fibres from the 
medulla is not known. They run in the buccal branch of the fifth nerve, 
instead of in the auriculo-temporal, leave this at the anterior end of the 
masseter muscle, and run backwards to the parotid gland along the 
duct.? 

There are no experimental investigations on the place of connection 
with nerve-cells of the cranial fibres to the parotid gland, but it has 
been supposed that this connection occurs in the otic ganglion. No 
ganglion cells have been described in the parotid gland itself. 

The secretory fibres for the orbital gland of the dog run in the 
buccinator branch * of the fifth nerve, and this is all that is known of 
their course. 

Historical.—The history of the discovery of the course taken by the 
cranial secretory fibres * may be briefly summarised as follows :— 


In 1851, Ludwig discovered in the dog secretory fibres for the sub- 
maxillary gland in the lingual branch of the fifth nerve. Rahn (and Ludwig) 
obtained in the rabbit secretion from the parotid, and sometimes from the sub- 
maxillary gland, on stimulating certain cranial nerve roots, after removing the 
brain. They found the effective nerve-roots to be those of the seventh and of 
the fifth, but their experiments do not show satisfactorily that the secretory 
fibres leave the medulla by way of these nerve roots. 

Bernard showed that the secretory fibres of the submaxillary glands came 
from the chorda tympani and so from the facial nerve. That the chorda 
tympani had some connection with the flow of saliva from the submaxillary 


1Cf. Heidenhain, Arch. f. Anat. u. Physiol., Leipzig, 1883, Supp. Bd., S. 158; 
Gaskell, Journ. Physiol., Cambridge and London, 1886, p. 29. 

* Moussu, Arch. de physiol. norm. et path., Paris, 1880, p. 68. (Cf. this paper also for 
secretory nerves of horse and pig.) Eckhard, Centralbl. f. Physiol., Leipzig u. Wien, 
1893. 

* For the method of dissection for experimental purposes, see Heidenhain, Hermann’s 
** Handbuch der Physiol.,” Bd. v. Th. 1, S. 38. 

‘Ludwig, Ztschr. f. rat. Med., 1851, N. F., Bd.i. S. 255; Rahn, zbid., S. 285; Schiff, 
Arch. f. physiol. Heilk., Stuttgart, 1851, Bd. x. 8. 581; Bernard, ‘‘ Lecons sur Ja physiol. et la 


| =a 


THE SYMPATHETIC NERVE-FIBRES. 483 


gland was suggested before Ludwig’s discovery of secretory nerves, and was 
definitely stated by Schiff in 1851. 

The course of the nerve-fibres to the parotid gland was also investigated by 
Bernard. He obtained secretion in the dog by stimulating the auriculo- 
temporal branch of the fifth nerve, and a cessation of reflex secretion by ex- 
tirpation of the otic ganglion. He considered that the secretory fibres came 
from the small superficial petrosal nerve, and that the superficial petrosals 
and the chorda tympani arose from the nervus intermedius of Wrisberg. 
Abolition of the reflex secretion in the rabbit was observed by Schiff on simple 
section of the small superficial petrosal. Loeb found that section of the 
tympanic branch of the glosso-pharyngeal nerve (i.e. of Jacobson’s nerve), or of 
the roots of this nerve in the skull, also abolished the reflex secretion, so that 
the secretory fibres of the small superficial petrosal come from the ninth and 
not from the facial. And Heidenhain obtained copious secretion on stimulat- 
ing Jacobson’s nerve. 

If the secretory fibres of the parotid really arise from the ninth nerve, the 
majority of the early observations form a singular record of inadequate experi- 
ments and hasty deductions. 


The sympathetic nerve-fibres and the nerve-cells with which 
they are connected.—All the salivary glands receive nerve-fibres from 
the cervical sympathetic. The fibres run from the middle or from the 
lower part of the superior cervical ganglion to the external carotid 
artery,and accompany its branches. On the arteries they form a plexus 
having two main longitudinal strands. The nerve-plexus, though chiefly 
of non-medullated fibres, contains some medullated fibres. In the artery 
to the submaxillary gland of the dog, there are twenty to thirty 
medullated fibres, a few of these being 5 » to 7 w in diameter, the rest 
2» to 3°5 w: the fibres run past the submaxillary ganglion in the hilus, 
without being, so far as can be seen, connected with it. 

The sympathetic fibres both secretory and vasomotor, for the sub- 
maxillary gland of the dog and cat, arise chiefly from the second thoracic 
nerve, to a less extent from the third, fourth, and to a slight and vary- 
ing extent from the first and fifth thoracic nerves.’ 

Langendorff? found that four months after hemisection of the 
spinal cord in the upper cervical region, the cervical sympathetic pre- 
sented its normal appearance. We may conclude, then, that the 
glandular nerve-fibres do not descend from a secretory centre in the 
medulla, and simply make their exit by the upper thoracic nerve roots. 

And there are several grounds for believing that the efferent sym- 
pathetic nerve-fibres issuing from a particular nerve root are the axis- 
cylinder processes of nerve-cells situated in the corresponding segment 
of the spinal cord. 


pathol. du systéme nerveux,” 1858, tome it; Schiff, ‘Lehrbuch. d. Muskel. u. Nerven- 
physiologie,” 1858-1859, S. 393; Czermak, Sitzwngsb. d. k. Akad. d. Wissensch., Wien, 
1860, Bd. xxxix. S. 526; Beitr. z. Anat. u. Physiol. (Eckhard), Giessen, 1860, Bd. ii. 8. 
214; 1863, Bd. iii. S. 49; Navrocki, Stud. d. physiol. Inst. zu Breslau, Leipzig, 1865, 
Heft 4, S. 123; Loeb, Beitr. z. Anat. u. Physiol. (Eckhard), Giessen, 1869, Bd. v. 8.1; 
Heidenhain, Arch. f. d. ges. Physiol., Bonn, 1878, Bd. xvii. S. 15; Bernard, ‘‘ Legons de 
physiol. opératoire,” 1879. 

1 Langley, Phil. Trans., London, 1892, vol. clxxxiii. p. 104. , 

2 Arch. f. d. ges. Physiol., Bonn, 1894, Bd. lviii. S. 165. Strictly speaking, the 
experiment only shows that the great majority of the nerve fibres of the cervical 
sympathetic have their trophic centre in the spinal cord below the hemisection. If even 
a considerable number of fibres had degenerated, they would have been absorbed in the 
time allowed, and would have left no recognisable trace. 


484 THE SALIVARY GLANDS. 


The sympathetic nerve-fibres are connected with nerve-cells in the 
superior cervical ganglion. If the cervical sympathetic be cut, the end 
towards the ganglion gives, in about four days, no effect on stimulation, 
but stimulation of the ganglion itself or of the fibres beyond it causes 
secretion and pallor of the gland (p. 522). On microscopical examination, 
the nerve-fibres are found to be degenerated, as far as the ganglion 
but not beyond it. Injection of nicotine causes for a time, varying with 
the dose, effects like those caused by degeneration of the nerve.! In 
the cat even 5 mgrms. of nicotine may be sufficient to paralyse the cervical 
sympathetic for a time, but very large amounts, eg. 500 mgrms., do not 
paralyse the nerves beyond the ganglion. From this and from other 
facts we deduce that the sympathetic fibres are not connected with any 
sympathetic nerve-cells peripherally of the superior cervical ganglion ; 
and there are reasons for believing that they are not connected with 
any nerve-cells between the ganglion and the spmal cord. In the dog 
the cervical sympathetic is much less readily paralysed by nicotine. 

Secretion of saliva produced by stimulation of the medulla 
oblongata.—Bernard? found that puncture of the fourth ventricle in 
the dog causes secretion from all the salivary glands, and if the puncture 
be a little above the spot, injury of which produces diabetes, the secre- 
tion may be confined to the submaxillary gland, and from this gland may 
be abundant. Loeb* showed that puncture of the medulla caused a greater 
secretion from the submaxillary or the parotid gland, according as the 
puncture was in the region of the nucleus of the ninth or of the seventh 
nerve respectively. With puncture on one side, the effect on the sub- 
maxillary gland of the opposite side was much greater than on the 
parotid of the opposite side. Griitzner and Chtapowski* observed that 
stimulation of the medulla oblongata caused abundant secretion if the 
chorda tympani was intact,a slight secretion if it was cut, but none 
after section of both the chorda and the sympathetic. 

Secretion of saliva produced by stimulation of the cerebral cortex. 
—It is not clear that the cortex of the cerebral hemispheres is connected 
with secretion—or indeed with any visceral phenomenon—in the way 
in which it is connected with the various body movements. 

Stimulation of the motor area, taking the matter broadly, causes 
secretion from the salivary glands, more readily than does stimulation of 
any other part of the cortex. So far as the experiments go, the region 
which causes maximum secretion from the submaxillary gland causes 
also maximum secretion from the parotid. Apparently the secretion 
ceases on cutting the cranial secretory nerve. 

The experiments in which the. portions of the cortex which cause 
secretion have been mapped out were made on dogs under curari. 
Those who have experimented on undrugged animals find that stimula- 
tion of the facial area causes no secretion so long as the resulting move- 
ment is confined to the facial muscles, and Eckhard® states that the 
secretion of saliva from the submaxillary glands only begins when the 
stimulus is continued long enough, or is made strong enough, to induce 


1 Langley and Dickinson, Proc. Roy. Soc. London, 1889, vol. xlvi. p. 425; Langley, 
Journ. Physiol., Cambridge and London, 1890, vol. xi. p. 131. 

2 “ Lecons de physiol. expérimentale,” 1856, Bd. ii. 

3 Op. cit., supra. 

4 Arch. f. d. ges. Physiol., Bonn, 1873, Bd. vii. S. 522. 

5 Neurol. Centralbl., Leipzig, 1889, p. 65. Cf. also Beitr. z. Anat. u. Physiol. 
(Eckhard), Giessen, 1876, Bd. vii S. 199. 


CHANGES DURING SECRETION. 485 


general convulsions; he considers that the saliva obtained in the 
curarised animal is due to an irradiation of nervous impulses, and not to 
a localised cortical stimulation. 


Kiilz! obtained no secretion from the submaxillary gland in unanesthet- 
ised dogs on stimulating the facial area, unless there was general tetanus, a 
condition in which Braun? had already observed a flow of saliva from the 
mouth. Lépine and Bochefontaine* obtained secretion in curarised dogs by 
stimulating the anterior portion of the cortex, including the facial area. The 
secretion was more abundant on the side stimulated. Bochefontaine,* shortly 
after, gave a more detailed account of the parts of the cortex from which 
secretion could be induced ; secretion was obtained by stimulating spots on the 
posterior part of the brain, and also by stimulating parts of the dura mater. 
The experiments show little or nothing as regards the question whether there 
are special areas in the cortex connected with the secretion. 

Bechterew and Mislawsky ® found, also on curarised dogs, that the region 
which caused secretion when stimulated with weak currents was more limited 
than that described by Bochefontaine. Stimulation of the anterior Sylvian and 
anterior composite convolutions caused secretion from both the submaxillary 
and parotid glands. Stimulation of the anterior limb of the sigmoid gyrus, 
and of the anterior extremities of the coronal and anterior ecto-Sylvian con- 
volutions, caused secretion from the submaxillary gland only. With stronger 
currents, secretion was sometimes obtained from the more posterior portions of 
the cortex. They found, unlike Lépine and Bochefontaine, no effect on 
stimulating the orbital convolution. 


CHANGES IN SALIVARY GLANDS DURING SECRETION. 


The changes which occur in salivary glands during secretion are 
progressive, and there is no sufficient reason for believing that the 
changes which occur in the cells at the end of a day’s active secretion 
differ in kind from those which oceur in the first ten minutes. 

The evidence is, it seems to me, decisively against the view that 
during salivary secretion there is a breaking down of the mucous or of 
other gland cells.° If saliva at any stage of secretion is allowed to run 
into alcohol, mercuric chloride, or other hardening reagent, disinte- 
grating cells are not seen in the sediment as it forms, nor nuclei beyond 
those which arise from the separated cells of Wharton’s duct and from 
leucocytes. And in the gland itself there is at no stage any sign of 
active cell division; the nuclei undergoing mitotic division are as rare 
as they are in the resting gland.’ 

Two fundamental changes undoubtedly take place in the gland cells 
during secretion. 

There is, first, an excretion of a greater or less amount of the sub- 
stance which has been previously formed in the cells; this substance, 


1 Centralbl. f. d. med. Wissensch., Berlin, 1875, S. 419. 

2 Beitr. z. Anat. u. Physiol. (Eckhard), Giessen, 1876, Bd. vii. S. 136. 

3 Gaz. méd. de Paris, 1875, p. 332. 

4 Arch. de physiol. norm. et path., Paris, 1876, p. 161. 

5 Neurol. Centralbl., Leipzig, 1888, p. 553. 

6It must be mentioned, however, that Heidenhain in his treatise (Hermann’s 
“Handbuch,” 1890, Bd. v.) maintains the view originally advanced by him, that mucous 
cells disintegrate to form part of the secretion. 

7 Langley, Proc. Roy. Soc. London, 1886, vol. xli. p. 362; Bizzozero, Virchow’s Archiv, 
1887, Bd. cx. S. 181. 

8 Heidenhain, Arch. f. d. ges. Physiol., Bonn, 1878, Bd. xvii. S. 43; Hermann’s 
“‘ Handbuch,” 1883 ; Lavdowsky, Arch. f. mikr. Anat., Bonn, 1877, Bd. xiii. S. 335. 


486 THE SALIVARY GLANDS. 


as it is formed, is for the most part, at any rate, stored up in the cells in 
the form of granules.t 

Secondly, there is a taking up of proteid material by the cells.2_ This 
occurs more or less exclusively in the outer part of the cells, and is the 
chief cause of the formation of an outer non-granular zone.t The taking 
up of fresh proteid substance is usually spoken of as a growth of proto- 
plasm; we may use the expression as a matter of convenience, bearing 
in mind that a large portion of the fresh proteid substance may be 
sunply deposited in interstices or larger spaces of the protoplasm. 

It is probable also that, during the whole period of secretion, there is 
a conversion of the newly taken up proteid into the material for 
secretion, or, in other words, the protoplasm is continuously disappearing 
and giving rise to granules. 

The loss of granules, together with the growth of protoplasm, causes 
the gland to become less white and less opaque to the eye. 


The nucleus, as was first shown by Heidenhain, is more obvious, and the 
nucleolus more conspicuous, in sections of the active gland than in those of the 
resting gland. The shrunken state of the nucleus in the resting gland appears 
to be due to the action of the hardening agent, for in teased glands, when the 
nucleus is visible, without serious alteration in the normal form of the cell, it 
is seen to be spherical. Nevertheless it is probable that there is some increase 
in the organic substance of the nucleus during prolonged secretion. 


During rest * the protoplasm decreases and the granules increase, and 
it would not be unnatural to suppose that no other changes take place in 
the cells but those associated with the conversion of protoplasm into a 
substance ripe for excretion. The point is one of great importance for 
the proper understanding of the secretory processes. Is there or is 
there not during rest any interchange between the cells and the lymph, 
beyond that of the taking up of oxygen and the giving off of carbonie 
acid? There is no experimental evidence to show whether the amount of 
oxygen taken up by the gland cells is so much in excess of the carbonic 
acid given off, that an increase in the weight of the gland takes place; 
but this is on general grounds probable enough, to prevent us from 
attributing offhand any increase in weight which may occur in a gland 
during rest to its cells having taken from the lymph proteid or substance 
other than oxygen. 

We may take first the evidence that glands increase in weight 
during rest. Obviously this is proved, if it can be proved that there is 
a decrease in weight during secretion. 

Heidenhain stimulated the chorda tympani on one side in a dog, and, 
after obtaining a considerable amount of saliva, killed the animal by 
bleeding it, separated the glands on the two sides from their capsules, 
and as far as possible from connective tissue, and then weighed them. 
He found that the active gland weighed less than the resting gland. 

1 Langley, Journ. Physiol., Cambridge and London, vol. ii. p. 261 ; Internat. Monatsehr. 
f. Anat. u. Histol., 1884, vol. i. p. 69; Proc. Roy. Soc. London, 1886, vol. xi. p. 362. 

? Heidenhain, Arch. f. d. ges. Physiol., Bonn, 1878, Bd. xvii. S. 43; Hermann’s 
‘* Handbuch,” 1883 ; Lavdowsky, Arch. f. mikr. Anat., Bonn, 1877, Bd. xiii. S. 335. 

3 It is perhaps hardly worth while to defend the use of the word ‘‘resting” for a gland 
which for some time has secreted but little, and the use of the word ‘‘active” for a gland 
which for some time has been secreting more or less copiously. The words lead to no 
ambiguity, and the objections to them appear to me purely pedantic. ‘‘ Active” and 


‘‘resting,” applied to any living tissue, are essentially relative terms ; it can hardly be 
doubted that there is greater chemical change when secretion is going on than when it is not. 


CHANGES DURING SECRETION. 487 


Three experiments were made ; the chorda tympani was stimulated on 
the left side. 


| 
Amount of Saliva Weight of Active Weight of Resting 
obtained. Gland. Gland. 
Experimentl .. 55 ¢.c. 5°04 grms. | 5°06 grms. 
ie 2 75 cc 15 6°86 ,, 
55 Bhai shiw.s 220 Cae 5 91- ©... 64365, 


In these experiments the left gland was the one that was caused to 
secrete, and there is some reason to think that the left gland is normally 
heavier than the right, for Bidder found this to be the case in eleven 
eases, and Heidenhain in two.! Pawlow,? however, noticed no appre- 
ciable difference in the amount of nitrogen contained by ten right 
and by ten left submaxillary glands of the dog. But so long as it is not 
shown that the right gland may be normally heavier than the left, we 
may fairly conclude that there is a loss of we eight by the gland during 
secretion and a gain of weight during rest. 

The question may be approached from another side. Microscopical 
examination shows decisively that during secretion the gland cells 
become smaller; they must then, taken together, decrease in weight 
unless the percentage of solids in them increases. But, according to 
Heidenhain, the percentage does not increase during secretion; on the 
contrary, it decreases. Thus, in one experiment upon a dog, in which 
about 220 e.c. of saliva were obtained by stimulating the chorda tympani, 
the percentage of solids in the resting gland was 28°53 per cent., and in 
the stimulated gland it was only 21:3 per cent., so that there were 7 per 
cent. less solids on the stimulated side. 


This, it must be remembered, applies to the gland as a whole. In con- 
cluding that there is a decrease in the percentage of solids in the actual gland 
cells, we assume that the percentage composition of the glands on the two sides 
is approximately the same, that there is no appreciable difference in the amount 
of blood and lymph upon the two sides, and that the connective tissues in the 
gland are too small in amount or too constant in composition to affect the result ; 
these assumptions, however, appear to be justifiable. 

The other experiments made by Heidenhain * were as follows :— 

1. The left chorda tympani was stimulated and 75 c.c. of saliva obtained. 
The right submaxillary gland contained 23 per cent. of solids, the left gland 
18-6 per cent.—a decrease of 4-4 per cent. 

2. The left chorda tympani was stimulated and 55 c.c. of saliva obtained. 
The right submaxillary gland contained 24 per cent. of solids, the left gland 
21°5 per cent.—a decrease of 3°5 per cent. 

Heidenhain found a slight decrease also in the percentage of solids on 
stimulating the cervical sympathetic. The time of stimulation is given, but 
not the amount of saliva obtained. 


2 On cit... pupil 
aCe ntralbl. f. Physiol., Leipzig u. Wien, 1888, S. 137. 

3 Stud. d. physiol. Inst. zu Breslau, Leipzig, 1868, Heft 4, S, 55. 
4 Op. cit., ‘p. 66. 


488 THE SALIVARY GLANDS. 


1. Sympathetic stimulated for two and a half hours. The resting gland 
had 25 per cent. of solids, the stimulated gland 23-6 per cent. 

2. Sympathetic stimulated for five and a half hours. The resting gland 
had 25 per cent. of solids, the stimulated gland 24:4 per cent. 


We may conclude, then, that during secretion the gland cells 
decrease in weight, and therefore that they increase in weight during 
rest. The increase in rest might be due, as we have said, to a taking up 
of oxygen. But the observations of Pawlow,! if they are well founded, 
show that, whether an increase in weight due to oxygen combinations 
occurs or not, there is during rest a not inconsiderable increase in the 
nitrogen of the glands, and this can hardly be due to anything else than 
an absorption of proteids. Pawlow estimated by Kjeldahl’s method the 
amount of nitrogen in the resting submaxillary gland of the dog on the 
one hand, and in the stimulated gland and in the saliva secreted by it 
on the other hand. He obtained saliva by stimulating the central end of 
the sciatic for one and a half to five hours. In ten (right) stimulated 
glands he found 1:872 grms. nitrogen. In the ten (left) non-stimulated 
glands he found 2718 grms. of nitrogen. Assuming, then, that the glands 
had the same amount of nitrogen to start with, the stimulated 
glands had lost during secretion about 1 of their nitrogen-holding 
substance. In the saliva secreted he found 0416 grms. of nitrogen, 
so that presumably the glands had taken up during secretion about 
0-1 grm. of nitrogen; this is about 5! of the total amount. The 
numerical results are not such as we should expect from the micro- 
scopical appearances of the gland cells, and it is desirable that the 
experiments should be repeated. 

The general characters of the cells of the lobular ducts suggest that 
they are not simply the lining cells of a conducting tube, but are rather 
active constituents of the gland, concerned either with adding to the 
saliva as it passes by them, or with subtracting from it. There is not, 
however, any clear evidence on the matter. It is true that when a con- 
siderable amount of methylene-blue is injected into the blood, and the 
glands are excited to secrete, small deep blue particles may be found in 
the duct cells as in the alveolar cells, but methylene-blue is so readily 
taken up by many tissues that little trust can be placed on this as show- 
ing a secretory function. The cells of the lobular ducts contain small 
granules in their outer portion,? and, according to Mislawsky and 
Smirnow,® these granules decrease during secretion, but it does not 
appear to me certain that the changes described by these authors are not 
due to conditions other than secr etory activity. Merkel* observed that 
the cells with striated epithelium, i.e. most of the lobular duct cells of 
the submaxillary and parotid glands, stained a deep brown when treated 
with pyrogallic acid in the presence of oxygen. He considered that the 
stain was due to the presence of calcium salts in the cells. This 
naturally suggested that the lobular ducts with striated epithelium might 
secrete calcium salts. But Werther ® has shown that the percentage of 
calcium salts in the sublingual saliva of the dog is rather greater than in 


1 Centralbl. f. Physiol., Leipzig u. Wien, 1888, S. 137. 

* Langley, Journ. Physiol., Cambridge and London, 1889, vol. x. p. 433. When the 
granules of the duct cells swell up and become indistinct, the substance beter them takes 
on the characteristic striated appearance seen in hardened specimens. 

3 Arch. f. Anat. u. Physiol., Leipzig, 1896, Physiol. Abth., S. 93. 

4 «Die Speichelrdhren,” Leipzig, 1883. 

5 Arch. f. d. ges. Physiol., Bonn, 1886, Bd. xxxviii. S. 293. 


ree a 


REFLEX SECRETION OF SALIVA. 489 


submaxillary saliva. And it happens that the ducts with striated 
epithelium are very scanty in the sublingual gland, whilst they are 
numerous in the submaxillary gland. 


REFLEX SECRETION OF SALIVA IN NORMAL AND IN OTHER 
CONDITIONS. 


In man, more complete observations have been made on the flow 
of saliva from the parotid than on that from the submaxillary gland, 
since the duct of the parotid is sometimes accidentally injured, so that 
the establishment of a parotid fistula becomes necessary. But some of 
the conditions of flow from either gland may be readily observed, when 
a cannula is simply placed in the opening of the duct of the gland into 
the mouth. 

In the dog, sheep, horse, and other animals, sometimes a permanent 
fistula, and sometimes a temporary fistula, of one or more of the glands 
is established. The observations have been made with and without the 
administration of anesthetics. 

Ordinarily, between meals, the large salivary glands—except the 
parotid olands of ruminants—do not secrete. But as the mucous 
membrane of the mouth is constantly kept moist, saliva must constantly 
be formed by the smaller glands of the mucous membrane. In some 
animals the amount of this secretion is very considerable; thus in the 
horse, during abstinence, 100 to 150 ¢.c. of saliva are, according to Colin,! 
formed in an hour. Probably during sleep the amount diminishes. 
There is little doubt that this secretion is produced reflexly by conditions 
affecting the mucous membrane of the mouth, and a slight increase in 
the strength of the stimuli probably sets in action the larger glands also. 

In ruminants there are some peculiarities. The parotid gland se- 
eretes continuously (Colin, Eckhard 2). The secretion is most abundant 
during feeding, rather less during rumination, and one-eighth to one- 
fourth the rumination rate during” rest.! During rest, the submaxillary 
glands secrete little or not at all, and it is a remarkable fact that 
rumination does not, as a rule, cause any secretion from these glands, 
although it increases the secretion from the parotid gland, and although 
feeding causes a secretion from all the glands. 


Colin found in ruminants a slight continuous secretion from the sub- 
maxillary and sublingual glands during rest. Ellenberger and Hofmeister? 
found none, but they noticed that there was occasionally a slight secretion 
from the submaxillary gland during rumination, and a more copious secretion 
during the act of drinking. According to these observers, there are occasional 
short pauses in the parotid secretion during rest. 

In ruminants, further, it has been said 4 that the secretion from the parotid 
gland continues after section of all the nerves running to it. In the ox, 
Moussu (1890) found that section of the buccal nerves diminished greatly, 
but did not quite stop, the parotid secretion. Eckhard (1893) states that 
section of these nerves does not affect the parotid secretion in the sheep; he 
found about 14 ¢.c. to be secreted in ten minutes, whether the nerves were 
cut or no. The matter requires further investigation. 


1 Op. cit. 2 Ztschr. f. rat. Med., 1867, Bd. xxix. S. 74. 

3 Arch. f. Anat. u. Physiol., Leipzig, 1887, Physiol. Abth. ., Supp. Bd., 8. 138. 

4 Centralbl. f. Physiol., Leipzig u. Wien, 1893, S. 365. Cf, Schwann, Beitr. 2. Anat. 
u. Physiol. (Eckhard), Giessen, Bd. vii. S. 170. 


490 THE SALIVARY GLANDS. 


In man during hunger, the sight, smell, or idea of food is sufficient 
to cause a secretion of saliva from all the salivary glands; and 
chewing insoluble substances has a similar, though apparently a less 
effect. 

Secretion in this way is said not to occur in lower animals. Thus 
Schiff? found in a dog with a parotid fistula, that no flow of parotid 
saliva was caused by the sight or smell of the meat the animal was 
endeavouring to obtain; when it was induced to bite a piece of wood, 
the meat still being in sight, there was shght secretion from the 
submaxillary gland but none from the parotid, but on placing sapid 
substances in the mouth there was at once a rapid secretion. And Colin 
states that, after a parotid fistula has been established in a horse, and 
when the animal is in a state of hunger, there is no secretion from the 
parotid when the animal is offered, but not allowed to take, corn, nor 
when it masticates oakum, although mastication of corn readily causes 
a secretion. 

Sapid substances taken into the mouth cause more or less secretion 
from all the salivary glands. In man all substances are effective, and 
drinking, wine for example, is sufficient.’ Acid placed on the tongue is 
apparently the most effective stimulant among the sapid substances, but 
there are not sufficient observations in man as to the amount of saliva 
produced by other substances, to allow a satisfactory opinion to be formed 
as to the relative effectiveness of salt, sweet, and bitter bodies. Masti- 
cation considerably increases the flow of saliva, probably by bringing 
the particles into better and more frequent contact with the mucous 
membrane. 

Chloroform and ether when inhaled cause secretion, by stimulating 
the gustatory nerve endings, and possibly also the other nerve-endings in 
the mucous membranes; if given by the trachea, they do not cause 
secretion. Alcohol, ether, or chloroform, when mixed with water and 
held in the mouth, cause a fairly free secretion of saliva. 

In carnivora, so far as the experiments go, acids (vinegar, tartaric 
acid) cause the most abundant secretion ; salts, either neutral or alka- 
line, a less secretion, but still a fairly copious one; bitter substances a 
much less secretion, and sugar little or even none. With sapid sub- 
stances in the mouth the secretion is increased by mastication. 


Thus Bernard,‘ in one experiment on a dog, in which cannule were placed 
in the ducts of all three glands, obtained a copious secretion from yinegar, less 
from sodium carbonate, still less from colocynth, and none from sugar or from 
water. The relative effect on the several glands was practically the same with 
all the substances. 

Schiff® obtained some secretion from the parotid fistula of a dog by 
placing sugar on the base of the tongue, but none by placing it on the tip. 

According to Colin,® weak acids, salts, or aromatic substances placed on 
the buccal mucous membrane give rise to no appreciable secretion from the 
parotid of the horse during abstinence, and do not sensibly increase the con- 


1 Colin and Prompt, 1874 (see Colin, ‘‘Traite de physiol. comparée,” ete., 3rd edition, 
p. 1), in the case of a girl with a parotid fistula, noticed that chewing a piece of ribbon 
caused a secretion of only one drop of saliva in two minutes. 

2 «*Tecons sur la physiologie de la digestion,” 1867. 
% Colin and Prompt (1874), case of parotid fistula (ef. supra). 
4“ Teeons de physiol. expér.,” 1856, tome ii. p. 82. 
> «* Tecons sur la physiol. de la digestion,” 1867, tome i. p. 186. 
6 Op. cit., p. 653. 


REFLEX SECRETION OF SALIVA. 491 


tinuous parotid secretion of ruminants ; but do nevertheless cause a secretion 
. . 7 - 

from the submaxillary and sublingual glands. His statements, however, are not 

quite consistent, and we may suppose that the difference is only one of degree. 


In herbivora, mastication is performed alternately on the two sides, 
the periods being usually one quarter to half an hour. In the horse, and 
probably in other herbivorous animals, the secretion from the parotid is 
much greater on the masticating than on the non-masticating side. In 
the horse two to three times as much saliva is usually secreted on the 
masticating as on the opposite side, but the ratio may be either greater 
or less than this (Bernard, Colin). It seems reasonable to suppose that 
this is due to the better contact of food with the mucous membrane of 
that side of the mouth. According to Colin, however, there is no such 
difference in the secretion of the submaxillary and sublingual glands. 

The amount of saliva secreted varies with the nature of the food. 
In man the data are not sufficient to form an estimate of any value, 
either of the relative amount of saliva secreted from the several glands, 
or of the total amount secreted in twenty-four hours. It is generally 
supposed that the total amount exceeds a litre a day.t 

Bernard? found that in the dog, when saliva was obtained reflexly, 
the submaxillary gland secreted about twice as much as the parotid, and 
about ten times as much as the sublingual. And these are approxi- 
mately the relative amounts obtained by injecting pilocarpine. The 
amounts secreted are roughly in proportion to the respective weights of 
the glands. 

In herbivora the volume of saliva secreted by the submaxillary and 
sublingual glands does not correspond with their respective weights. 
According to Colin, the parotid gland of the horse secretes fifteen to 
twenty times the volume of saliva secreted by the submaxillary gland, 
but is only about four times its weight. And in the ox the parotid 
secretes four to five times as much saliva as the submaxillary gland, 
though it is slightly less in weight (cf. Table, p. 477). 

Colin estimates that in the horse the total quantity of saliva secreted 
in a day is about 40 litres. 


The total quantity of saliva may be estimated in two ways—(1) By com- 
paring the weights of a certain amount of food before and after mastication 
and swallowing, the food after mastication being collected from an cesophageal 
fistula; and (2) by noting in different experiments the quantity secreted by 
each gland during a given period of feeding. Colin found, by the first method, 
that a horse secreted 5000 to 6000 grms. of saliva in an hour, when fed with 
hay, one-half of this when fed with grass, and one-third more than this when 
fed with oats. 

During digestion, according to Colin, the submaxillary gland of one side 
secretes 25 to 30 c.c. of saliva in fifteen minutes ; the parotid secretes 500 to 
1000 (about) in fifteen minutes, if mastication takes place on this side.* 

In the ox he estimates that during three hours’ mastication, and five 
hours’ rumination, about 40 litres of saliva are secreted, and that 16 litres are 
secreted during the sixteen hours of rest. 


Electrical excitation of the central end of the lingual or of the glosso- 
pharyngeal causes secretion from all the salivary glands. The secretion 


1 Some data are given by Tuczek, Zschr. f. Biol., Miinchen, 1876, Bd. xii. 8. 534. 
2 “*Lecons de physiol. expér.,”’ 1856, tome ii. p. 82. 
3 For other observations on this point, cf. Ellenberger and Hofmeister, op. cit., supra. 


492 THE SALIVARY GLANDS. 


is less copious than that obtained by placing acids in the mouth, and it 
is more copious on the side stimulated than on the opposite side. 

A special relation has also been said to exist between the state of 
the mucous membrane of the stomach and the secretion of saliva. Thus 
it has been said that a secretion of saliva is induced by the contact of 
various substances with the gastric mucous membrane! This, however, 
is not satisfactorily proved. Braun? observed a dog, in which a gastric 
fistula had been established, and a cannula placed in Wharton’s duct. 
No secretion of saliva was caused by introducing into the stomach, 
flesh, acetic acid, ether, nor by irritating the mucous membrane with a 
sponge. 

Stimulation of the central end of the vagus has rather variable 
results on the submaxillary secretion of the ‘dog. It usually causes 
secretion after a long latent period, and the secretion may continue for 
some time after the cessation of the stimulus. Oehl? obtained secretion 
although the stimulation caused no vomiting or arrest of respiration ; the 
secretion occurred from both glands, but was greater on the side stimu- 
lated. Buff, as a rule, only obtained secretion when there was some 
body movement. 

Bernard noticed that a flow of saliva may be obtained by stimulating 
the sciatic * and various other sensory nerves; 1t may, indeed, be obtained 
by stimulating any sensory nerve in the body. This reflex secretion is 
abolished by deep anzesthesia; whether it ceases coincidently with the 
production of anesthesia is, however, uncertain. According to Buff? 
the secretion does not occur in uncurarised animals, unless the stimulus 
produces also a reflex body movement. 

The gustatory reflex secretion is caused wholly by impulses passing 
down the cranial secretory nerves. But a secretion may, in certain 
circumstances, be caused by impulses passing along the sympathetic 
nerve ; for example, when the central end of a sensory nerve is stimu- 
lated, the secretion, so far as is known, is always accompanied by a con- 
striction of the blood vessels of the gland. 

In man, cases sometimes occur in which there is a permanent absence 
of secretion from the large salivary glands, and from the glands of the 
mucous membrane of the mouth, “Such cases are rarer in men than in 
women. In women the loss of secretory power usually comes on after 
middle life, and may be the result of an emotional shock. For some 
time pilocarpine will still cause a secretion of saliva (Hadden), but 
eventually it causes none, though it still causes sweating.® The 
absence of secretion is no doubt due to a derangement of the reflex 
nervous mechanism, so that impulses passing up the afferent nerves no 
longer give rise to efferent impulses. The lack of normal functional 
activity “probably causes a gradual atrophy of the glands, and a diminu- 
tion of irritability of the nervous and glandular structures, so that 
eventually pilocarpine—or the amount of it which can be given safely— 
no longer produces a flow of saliva. 


1 For an account of papers on the reflex secretion of saliva, cf. Buff, Beitr. 2. Anat. u. 
Physiol. (Eckhard), Giessen, 1888, Bd. xii. S. 3. 

2 Ibid., 1876, Bd. vii. S. 44. 

° Compt. rend. Acad. d. sc., Paris, 1864, tome ix. p. 336. Secretion on stimulation of 
the central end of the vagus was first obser ved by Bernard, 1859. 

4 Cf. also Owsjannikow and Tschiriew, Mélanges biol. Acad. imp. d. sc. de St.-Péters- 
bourg, 1872, tome viil. p. 651. 

Oe cit. § Hutchinson, ef. Hadden, Brain, London, 1889, vol. xi. p. 484. 


THE DYSPNGIC SECRETION. 493 


THE DySPN@IC SECRETION. 


At a certain stage of dyspnea the saliva flows with considerable 
rapidity from all the salivary glands. The time at which it begins and 
its amount are dependent upon the degree of anesthesia. In anesthesia, 
the secretion does not usually begin until the stage of expiratory convul- 
sions. With a large excess of anesthetics, the animal may be killed by 
asphyxia without any secretion occurring, or with only a trifling amount. 
When a copious secretion occurs it is due to impulses passing down the 
cerebral nerve fibres, but some secretion may be obtained after section 
of these nerve fibres. In such case there is also contraction of the 
glandular arteries. Whether dyspnea is capable of producing a secre- 
tion after section of the cerebral nerve and excision of the superior 
cervical ganglion, has not been sufliciently investigated. 


STIMULATION OF THE CRANIAL NERVE SUPPLYING A SALIVARY 
GLAND. 


On some general features of the secretion.—A flow of saliva can 
be obtained from any of the salivary glands by electrical, mechanical, or 
chemical stimulation of the cranial secretory nerves. It need hardly be 
said that the interrupted current is the most effective form of stimulus. 
A very weak interrupted current, which cannot be felt on the tongue, is 
sufficient to cause a secretion. Within certain limits the rate of flow of 
the saliva increases with the strength of the stimuli, but strong currents 
rapidly injure the nerve at the point of stimulation. Even with 
moderate currents a very slight shifting of the electrodes on the nerve 
usually causes a marked increase in the rate of secretion, a fact which it 
is important to bear in mind in collecting for analysis different samples 
of saliva, secreted under different conditions. 

The flow of saliva with a moderate strength of current is very rapid; 
thus the submaxillary gland in the dog may secrete in five minutes an 
amount of saliva weighing as much as the whole gland. 

The nerve can be stimulated electrically for half an hour to an hour, 
and probably with proper precautions very much longer, without the 
flow of saliva ceasing. Pilocarpine in successive doses (cf. p. 513) will 
cause a secretion for, so far as we know, an indefinite time. 

In protracted electrical stimulation the maximum amount of saliva 
is obtained by stimulating for short periods, with short intervals of rest ; 
the stimulation being stopped each time as the secretion becomes slow. 
In this way in ten to twelve hours about 250 cc. of saliva can be 
obtained from the submaxillary gland of the dog, and a half to two- 
thirds of this amount from the parotid. The rate of flow gradually 
diminishes during the progress of the experiment. With a given 
streneth of current, the maximum rate of secretion is produced with a 
rate of interruption of about forty a second. 


According to Wedensky, rapid shocks, such as 100 to 250 a second, cause a 
change in the nerve-endings, so that they soon cease to transmit nervous 
impulses. His most striking experiment is the following :—Two pairs of 
electrodes are placed on the chorda tympani, shocks of moderate rate are 
passed through the lower, and of rapid rate through the upper; the secretion 


1 Wedensky, Compt. rend. Acad. d. sc., Paris, 1892. 


494 THE SALIVARY GLANDS. 


soon becomes slow or stops altogether, but, on cutting off the rapid shocks 
from the upper electrodes, the stimuli at the lower electrodes become again 
effective, and the secretion starts once more. ‘The results are similar to those 
he obtains with motor nerves to skeletal muscle. 


The real latent period of the gland cells cannot be accurately deter- 
mined by any direct method, and in consequence it is customary to speak 
of the interval between the moment of stimulating the nerve, and the 
moment at which the movement of saliva occurs in the duct, as the 
latent period. When the cranial nerve is stimulated with a weak 
current, there is an obvious interval—usually two to four seconds— 
between the moment of application of the stimulus and the appear- 
ance of saliva in the cannula, and this is the case although the 
secretion when it occurs is not scanty. When stronger currents are 
used, and the secretion is copious, the latent period is much dimin- 
ished. On the other hand, when the secretion is scanty, the latent 
period is very much prolonged, whatever the strength of current; thus, 
after a small dose of atropine, it may be half a minute or even more. 

The percentage of organic substance in saliva obtained from differ- 
ent salivary glands varies considerably ; in each, as we shall see, it 
varies in different circumstances s, and in each it may be small (0:2 
to 05 per cent.). But, other things being equal, the submaxillary 
saliva has usually a higher percentage of organic substance than 
either the sublingual or the parotid saliva. 

There is a curious difference in the percentage of salts found in 
different salivas. In the dog the maximum percentage of salts in the 
parotid saliva is about 0°68, in that of the submaxillary gland about 
0°77, and in that of the sublingual gland about 1:0.1 ‘In the rabbit 
the parotid saliva has a maximum percentage of about 0°85.? 

After action of a strong stimulus.—Strong stimulation of the 
cranial nerve alters the gland it supples in such a way, that the 
saliva secreted shortly afterwards has a higher percentage of solids 
than it otherwise would have had.? Thus, in the experiment quoted 
on p. 501, the first weak stimulation of the chorda tympani caused 
secretion of a saliva containing 0°52 per cent. of organic substance, 
whilst, after a strong stimulation, a second weak one caused a secre- 
tion having a percentage of 1:07 of organic substance. 

This, howev er, only holds when successive small quantities of 
saliva are collected; with larger quantities, as 10 cc to 12 ce, 
no such after action is observed (Werther). 


STIMULATION OF THE SYMPATHETIC NERVE SUPPLYING A 
SALIVARY GLAND 


Ludwig‘ (in 1856) discovered the secretory power of the sym- 
pathetic ; ‘he obtained a secretion from the submaxillary gland of 
the dog, by stimulating both the cervical sympathetic and the nerve 
filaments on the gland artery. 


1 Werther, Arch. f. d. ges. Physiol., Bonn, 1886, Bd. xxxviii. S. 293 ; Langley and 
Fletcher, Phil. Trans., London, 1889, vol. clxxx. p. 109. 

2 Heidenhain, Arch. f. d. ges. Physiol., Bonn, 1878, Bd. xvii. 8. 40. 

3 Heidenhain, op. cit., 1878. 

+ Quoted by Gzermak, Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1857, Bd. XXY. Sores 
Czermak also obtained secretion on stimulating the cervical sympathetic. 


STIMULATION OF THE SYMPATHETIC NERVE. 495 


Eckhard! noticed that the saliva secreted by the submaxillary 
gland, on stimulation of the sympathetic, was more viscid and con- 
tained a higher percentage of solids than that obtained by stimulat- 
ing the chordo-lngual. 

Neither from the submaxillary, the sublingual, nor the parotid 
gland of any animal does the sympathetic produce a secretion which 
approaches in amount that which is produced by the cranial nerve. 
Unless the gland has been secreting under the influence of the cranial 
nerve, before stimulation of the sympathetic (cf. p. 496), this stimula- 
tion causes secretion of a few drops only, and it may be much less. 
Thus, in the dog, stimulation of the sympathetic for a minute will 
ordinarily produce two or three drops from the submaxillary gland, and 
perhaps half a drop from the sublingual. 

In most of the earlier experiments upon the parotid gland of the 
dog, either no secretion was obtained by repeated stimulation of the 
sympathetic, or a total amount not exceeding a few drops. This is, 
however, only a more marked instance of the slow secretion which the 
sympathetic, after the first few stimuli, causes in the submaxillary and 
sublingual glands of the same animal. If the parotid gland, after 
sympathetic stimulation, during which no secretion or a trace only has 
been obtained, be hardened, and sections be cut, the lumina, ductules, 
and duct will be found distended with secretion. 

The maximum total amount of saliva is obtained by stimulating the 
sympathetic for short periods, with short intervals of rest. Stimulated 
in this way—say, during every other half-minute—the sympathetic will 
give from the submaxillary gland of the dog 35th to g5th of the 
quantity of saliva that would be obtained by similar stimulation of the 
chorda tympani. 


With protracted stimulation the secretion may continue slowly for several 
minutes, but sooner or later it stops. Roughly speaking, and within rather 
narrow limits, the amount of saliva obtained is inversely proportional to the 
duration of the previous stimulus and directly proportional to the length of 
the preceding period of rest. After repeated stimulation of the sympathetic, 
there may be no visible secretion for half a minute to a minute after the 
beginning of the stimulation, and occasionally the slight secretion which 
occurs only begins after the stimulation has ceased. 

Heidenhain, stimulating for a quarter of an hour during each half-hour, 
obtained a secretion from each stimulation for eleven successive hours, 7.¢. as 
long as the experiment lasted. 


In different glands, and in the same gland in different animals, the 
freedom of secretion of sympathetic saliva compared with that produced 


-by the cranial nerve, and the percentage of organic substance in the 


saliva, varies considerably. I have already mentioned that the 
sympathetic causes some secretion from the submaxillary gland, and 
often none from the parotid. Relatively, rather more sympathetic 
secretion is obtained from the glands of the cat and rabbit than from 
those of the dog. The sympathetic saliva from the submaxillary gland 
of the dog contains 1 to 3 per cent. of organic substance, that from the 


1 Adrian and Eckhard, Beitr. z. Anat. u. Physiol. (Eckhard), Giessen, 1860, Bd. ii. 8. 83. 
Bernard, Journ. de l’anat. et physiol., ete., Paris, 1858, tome ii. (1) p. 657, stated that 
sympathetic saliva was much more viscid than chorda saliva. The sympathetic secretion 
in the sheep and rabbit was noticed by v. Wittich, Virchow’s Archiv, 1866, Bd. xxxvii. S, 93. 


496 THE SALIVARY GLANDS. 


parotid of a rabbit 5 to 6 per cent. In the cat the percentage of 
organic substance in sympathetic saliva from the submaxillary gland is 
small (about 0:5 per cent.), and less than that in the chorda saliva. 

The percentage of salts in sympathetic saliva does not exceed the 
percentage of the salts in saliva produced by stimulating the cranial 
nerve. 


The analyses of the parotid saliva in the rabbit have been made by 
Heidenhain.! I extract the following from one experiment :— 


Parotid Gland—Rabbit. 


| | 1 | 
| | 
| Time or calles sera of | a Onene Percentage of 
ing Saliva. Saliva. ‘ Salts. 
| | Substance. 
| | 
| Saliva from stimulating both | | | 
sympathetics . : . 38 mine | 26ec | 4°93 0°54 
Pilocarpine saliva from one | 
| gland : [Fas 55 hee 4 epi Bes 0°65 | 0°81 


| | 


The sympathetic saliva in the cat? is, as I have said, usually less viscid 
than chorda saliva. But it is possible that a strong or prolonged stimulation 
of the sympathetic might give rise to a saliva with a higher percentage of 
solids than the chorda saliva. JI append an analysis of sympathetic and chorda 
saliva in the cat, obtained by moderately strong interrupted currents. 


| 
| 
| 
| 


| | 

| Percentage | 

seen Percentage Percentage | 

| oes of Salts. of Solids. | 

| | 
| Chorda saliva . ; | 0°87 0°34 12 
Sympathetic saliva . : 0°43 0°28 0°70 


The sympathetic secretion in the cat is very much like the “augmented” 
secretion of the gland of the dog (cf. infra), in that it starts quickly, 
quickly becomes slow, and is watery. It differs in the rapidity of recovery 
from the effect of immediately preceding sympathetic stimulation. The 
maximum amount of secretion is obtained by stimulating fifteen seconds out 
of every thirty, or even for shorter periods. 


In certain circumstances the sympathetic may produce a brief rapid 
secretion from any or all of the salivary glands. That is the case when 
it is stimulated shortly after stimulation of the cranial nerve. There is 
a rush of saliva, quickly following the sympathetic stimulation, reaching 
its maximum in a few seconds, and, after about seven to ten seconds, 
rapidly declining. A very brief stimulation of the cranial nerve is 
sufficient to increase in this way the amount of saliva obtained from 
the sympathetic. And thus, if the cranial nerve and the sympathetic 
nerve be stimulated alternately, a not inconsiderable quantity of 


1 Arch. f. d. ges. Physiol., Boun, 1878, Bd. xvii. S. 38. 
2 Langley, Journ. Physiol., Cambridge and London, 1878, vol. i. p. 86; 1885, vol. vi. 


p. 92. 


STIMULATION OF THE SYMPATHETIC NERVE. 497 


sympathetic saliva may be obtained. It is convenient to have some 
name for this unusually rapid sympathetic secretion, and I have called 
it the augmented secretion.} 

In the dog, the saliva of the augmented secretion is, in its physical 
characters and apparently in its percentage composition, intermediate 
between sympathetic saliva and that obtaimed by stimulating the 
cranial nerve. 

The augmented sympathetic saliva from the submaxillary gland of 
the dog is three to ten times as abundant as ordinary sympathetic 
saliva. In fifteen seconds about } c.c. is usually secreted, but there 
may be as much at }¢.c. The amount of the augmented secretion from 
the parotid is one-third to one-half that of the submaxillary gland. 

The augmenting effect of stimulating the cranial nerve disappears 
in time, although the sympathetic is not stimulated in the interval. 
In the submaxillar y gland of the dog the greater part of the effect dis- 
appears in ten to fifteen minutes. In the parotid, it has usually com- 
pletely disappeared in ten minutes. The rate of disappearance does not 
seem to be affected by the injection of atropine. 

Mere vascular dilation does not cause an augmented secretion, for 
if atropime be given in sufficient quantity, to paralyse completely the 
cranial secretory nerves, stimulation of the cranial nerve, which still 
gives largely increased blood flow, does not increase to any considerable 
extent the sympathetic saliva obtained subsequently. 

When the sympathetic nerve is stimulated two or three times in 
succession for rather short periods, say of thirty seconds, the augmenting 
effect of a preceding cranial nerve stimulation does not necessarily cease 
with the first stimulation, but is visible, though to a much less degree, in 
the second, and it may be in later stimulations. In the case of the dog’s 
parotid the third stimulation usually gives no secretion at all. 


The following extracts from the notes of experiments will illustrate the 
statements made above with regard to the augmented secretion :— 


Submaaillary Gland—Dog—Stimulation of the Sympathetic after moderate 
Stimulation of the Chorda Tympant. 


Saliva secreted in mm. during 
successive 30 secs., 355 mm. 
= 25 CHE 


2 20 4 2 1 
Nerve stimulated °. 


Sy. 


Rey 
Sq le 
— 
we 
— 
_ 
Qo 
co 
Pe 
bo 
oOo 
= 


In the second sympathetic stimulation the flow of saliva was 16 mm. 
during the first fifteen seconds, and 4 mm. during the second fifteen seconds. 


Submaxillary Gland—Dog—Stimulation of the Sympathetic after brief 
Stimulation of the Chorda Tympani. 


Saliva flow every 
30 secs. in mm. 0 5 1 0 15 1 0 0 0 15 
Nerve stimulated Ch. Sy. Sy. 


(for 2 to 3 secs.) 


toe 


Longer stimulation of the chorda tympani has little effect upon the 
maximum rate of flow of the augmented secretion, but it leads apparently to a 
less rapid fall after the maximum is attained. 

1 Journ. Physiol., Cambridge and London, 1889, vol. x. p. 291. 
VOL. I.—32 


498 THE SALIVARY GLANDS. 


Parotid Gland—Dog—Stimulation of the Sympathetic after Stimulation 
of Jacobson’s Nerve. 
Saliva flow every interval 11) 
30 secs. in mm. Op So els 21s OO pe Olena 764 ssa tdO) v0, (vou 0) eelOe 


( minutes 5 
Nerve stimulated Jin (SY. S) AS) AS dle Sy. Sy. J. Sy. 
A brief rapid increase in the flow of saliva is obtained by stimulating 
the sympathetic during the action of pilocarpine and other alkaloids 
which cause a continuous free flow of saliva. After the first rapid rise 
the secretion becomes slower, and in the parotid gland of the dog stops 
altogether ; in the submaxillary gland the secretion slowly continues. 


Parotid Gland—Dog—Pilocarpine Injected. 
Rise of saliva 6 6 35 7 3 0 0 


stim. symp. 


EFFECT OF PROTRACTED STIMULATION ON THE AMOUNT AND 
PERCENTAGE COMPOSITION OF SALIVA. 


During protracted stimulation, as was shown by Becker and Ludwig,! 
the percentage of solids in the saliva diminishes. They found a marked 
diminution in the percentage of organic substance; and generally, but 
not always, some diminution in the percentage of salts. The most striking 
experiment given by them is the followmg. The chorda tympani was 
stimulated, and successive portions of the saliva were analysed :— 


Amount Percentage of Percentage Percentage 
of Saliva Organic te) of 
Collected. Substance. Salts. Solids. 
1st portion . ; g : 10°6 119 0°79 1°98 
gndl - - - : 13°2 1°26 0°63 1°89 
ards: 14°4 0°62 0°54 1°16 
ath “; 13:9 0:27 0°48 0°75 


The decrease in the percentage of salts is probably connected, as 
Heidenhain has pointed out, with the slower rate of secretion of saliva 
in the later portions collected. 

Heidenhain* showed that the percentage of solids sinks during pro- 
tracted secretion, not only in chorda saliva,? but also in sympathetic 
submaxillary saliva. In the following experiment the sympathetic was 
stimulated at short intervals during five and a half hours; the first and 
the last portions of saliva collected were analysed :— 


Time of Amount Percentage 
Collection. Collected. of Solids. | 
_ 
: 
First portion . : : 80 minutes 0°68 grm. 3°73 
Last Ar z : > 88 54 O:39h... 1°49 | 


1 Zischr. f. rat. Med., 1851, N. F., Bd. i. S. 278. 

2 Stud. d. physiol. Inst. zu Breslau, Leipzig, 1868, S. 65. 

3 We have to refer so frequently to the saliva obtained from the submaxillary gland— 
(1) by stimulating the chorda tympani, (2) by stimulating the sympathetic, (3) by 
injecting pilocarpine—that we are driven to adopt the terms, chorda saliva, sympathetic 
saliva, and pilocarpine saliva, for the saliva obtained respectively in these circumstances. 


RELATION OF RATE TO PERCENTAGE COMPOSITION. 499 


He? showed, further, that in parotid saliva, obtained by stimulating 
Jacobson’s nerve, there is similarly a decrease in the percentage of solids 
as the secretion goes on, and, no doubt, it is a general rule for all 
salivary glands. 


RELATION OF THE RATE OF SECRETION TO THE PERCENTAGE 
COMPOSITION OF SALIVA. 


Heidenhain 2 investigated the relations existing between the rate of 
secretion and the percentage composition of saliva. He showed that an 
increase in the rate of secretion was accompanied by an increase in the 
percentage of salts, and this whether the gland had secreted for a long 
time or for a short time. 


An example of this is given in the following experiment, in which the 
chorda tympani was stimulated with currents of varying strength, and a few 
c.c. of saliva collected in each case. The samples of saliva are arranged in the 
table in the order of their rate of secretion :— 


Order of sample. mynd il 7 3 8 4 2 9 6 
Mean rate of secretion 

permin. ine.c . 5 lle 18 19 ede ie AS 2°0 2°2 2°5 32 
Percentage of salts . . “34 “29 "25 “32 37 58 “44 ay 58 


It will be noticed that the percentage of salts does not quite go hand 
in hand with the rate of secretion. But it is almost impossible to keep 
the rate of secretion constant during the time of collecting a sample of 
saliva, and to this the divergences may, in the main, be attributed. 


A closer relation between the rate of flow and the percentage of saliva was 
observed by Werther,’ and by Langley and Fletcher.* Heidenhain found the 
percentage of salts to have an upper limit, with increased rate of secretion. 
This he gave as ‘5 to ‘6 per cent., though in one case “66 per cent. was found. 
Becher and Ludwig had earlier found in one case *78 per cent. Werther, and 
Langley and Fletcher found the maximum percentage to be ‘77. From the 
observations of the latter, it appears that the faster the rate of secretion, the 
less increase there is in the percentage of salts for a given increase in rate of 
secretion. This is indicated in the following table :— 


| 
Increase in Percentage 
of Salts, correspond- 
Percentage of Salts. ing to an Increase of 
01 c.c. per Minute 
in the Rate of Secretion. 


Rate of Secretion per 
Minute in c.c. 


“400 “472 
04 
500 512 
760 *b99 033 
“900 616 012 
1°333 628 003 


1 Heidenhain, Arch. f. d. ges. Physiol., Bonu, 1878, Bd. xvii. S. 23. During eleven 
hours’ stimulation the percentage of solids sank from 0°88 per cent. to 0°49 per cent. 

2 Ibid., Bd. xvii. p. 1. Earlier observations on the same lines were given by him in 
1868 in his ‘‘ Studien.” 

3 Arch. f. d. ges. Physiol., Bonn, 1886, Bd. xxxviii. 8. 293, 

4 Phil. Trans., London, 1889, p. 109. 


500 THE SALIVARY GLANDS. 


The experiments on the parotid gland given by Heidenhain show a 
general but not a very close relation between the rate of secretion and the 
percentage of salts in the saliva. 


Sodium chloride forms the larger part of the salts in saliva. The 
percentage both of this and of sodium carbonate varies directly with the 
rate of secretion. The salts msoluble in water, the chief of which is 
calcium carbonate, do not seem to follow this rule, or at any rate only 
partially, for, whilst there is sometimes an increase in the percentage 
of insoluble salts, with increased rate of secretion, this is by no means 
always the case;! they appear to decrease in amount during the 
progress of the secretion, as if in part they arose from a store in the 
gland itself. 


The following experiment from Werther will illustrate the variations in 
the percentage of different salts. The saliva was obtained from a dog by 
stimulating the chorda tympani :— 


A t | Rate of Percentage | p, ye Percentage ; 

of Saliva Secretion of emcee. f P vitae eee 

btained per Minute Organic Insoluble = 

an ae Sn c.c. Substances. Salts. Salts. NaCl. | Na,COs;. 
Jet) 17°6 0176 0:30) | 0°35 0°019 0-29 | 07042 
PNET | 14°2 0°890 i ah 0°43 0°060 0°30 0°067 

| | 
3 16:2 0°216 One 0°21 0°015 0°18 0:029 
4 16-2 1:082 0°64 |} 0°42 0°030 0°27 0-046 
mt 


The relation thus determined between the percentage of salts and 
the rate of secretion, holds for chorda saliva and for pilocarpine saliva? 
secreted under normal conditions. But it is not a universal rule. Thus, 
sympathetic saliva has a much higher percentage of salts than corre- 
sponds to its rate of secretion, if chorda saliva be taken as a standard of 
comparison. And the rule does not hold for chorda or pilocarpine saliva, 
when the blood flow through the gland is much diminished, or when 
the character of the blood is much altered. On this I shall say more 
presently. 

Heidenhain also showed that in a fresh gland an increase in the rate 
of secretion is accompanied by an increase in the percentage of organic 
substance in the saliva. In the experiment given below, for example, 
an increase in the rate of flow of the submaxillary saliva of the dog, 
from 0:14 c.c. to 0°87 cc. in one minute, was accompanied by an increase 
from 0°52 to 1:54 in the percentage of organic substance. But when 
a certain amount of the stored-up substance of the gland cells has been 
secreted, an increase in rate of secretion no longer Jeads to an increase 
in the percentage of organic substance in the saliva secreted in a 
given time. 

The closeness of the relation between percentage of organic sub- 
stance and rate of secretion from a fresh gland seems to me to have 
been much exaggerated. No doubt there is a relation of the kind, but, 
in actual experiments, it is frequently overridden by other factors. 


1 Werther, op, cit. * Langley and Fletcher, op. czt., supra, 


SOME GENERAL CHARACTERS OF SALIVA. 501 
Interval SATIT ADC! f 
eae aus See | es | 
one before it. ; Substance. Solids. 
3:5 0-14 0°52 0-22 0-74 
2 minutes | 3°5 0°87 1°54 0°56 2°10 
Bui, 30 0°66 1°63 0-45 =| 2°08 
PAL & 2°8 0-11 1:07 0°36 1°44 
ae 3°0 1:00 0-91 0°49 141 
Deey 5: 30 0°50 0-76 0°39 116 
fer 275 0-13 0°48 0°30 0°78 
Bh Si 3:1 | Oey 0°51 0°38 0°90 
ae 31) 2-8 0°31 0°42 0°36 0-79 


SoME GENERAL CHARACTERS OF SALIVA, AND ITS MICROSCOPIC 
CONSTITUENTS. 


The viscidity of saliva, secreted by mucous glands, is generally in 
proportion to the percentage of mucin which it contains. This, of 
course, would not be the case, if the amount of alkaline salt in the 
saliva increased in much larger proportion than the amount of mucin, 
for, with a given quantity of mucin, the viscidity of the fluid varies with 
the amount of the solvent. 

Saliva, from albuminous or from mixed glands, may be either watery 
or thick, irrespective, within certain limits, of the percentage of organic 
substance present. Sublingual saliva and parotid saliva of the dog, 
when they have a high percentage of organic substance, have a tendency 
to turn into a jelly-like mass, and this may further separate into a elot 
and clear fluid. 

In very watery saliva, freshly secreted, which has not been allowed 
to stand in the ducts, and which is examined without delay, nothing 1s 
to be seen under the microscope. 

When saliva is allowed to stand a short time in the ducts, car- 
bonic acid is given off from it, and, in consequence, calcium carbonate 
is precipitated; the precipitate renders the saliva cloudy, and under 
the microscope appears as very fine particles, or groups of particles. 
On irrigating such a specimen with dilute mineral acid, the particles 
are dissolved. The saliva also may contain leucocytes, and will certainly 
do so if it has been allowed to stay long in the gland ducts. In ordinary 
experimental conditions, leucocytes collect in the connective tissue of 
the glands, and migrate, at times in large numbers, into the ducts. The 
leucocytes at first show amoeboid movement; later, they swell, become 
vacuolated, and form the bodies which have been called salivary cor- 
puscles. The saliva may also contain some cells from the ducts 
which have been separated or injured by insertion of the cannula, 
some isolated nuclei, either of duct cells or of leucocytes, and occasionally 
a few small fat globules. 


502 THE SALIVARY GLANDS. 


In viscid saliva of the submaxillary gland of the dog, spheres or 
clumps of secreted substance are present. The number and the 
character of these vary broadly with the viscidity of the freshly-secreted 
saliva, and are, so far as I have seen, independent of the way in which 
the secretion is brought about. As sympathetic saliva is usually much 
more viscid than chorda saliva, it usually contains these constituents in 
much larger number.! 

The spheres vary in appearance. In the more viscid specimens of 
saliva they are pale, have a very faint outline, and appear homogeneous 
(pale spheres). As a rule they are 2 to 4 w in diameter, but 
larger and smaller ones occur. In the less viscid specimens of saliva 
some spheres like these are also found, but most are more watery- 
looking and are still paler (very pale spheres) ; they vary much in size, 
but on an average are larger; they are apparently the swollen forms of 
the ordinary pale spheres. There are also, especially in more watery 
saliva, spheres which differ from the preceding in having a fairly sharp 
outline (vacuolar spheres). In the more viscid forms of saliva, clumps 
occur as well as the pale spheres, and they are more numerous the more 
viscid the saliva. 

In saliva freshly secreted and freshly examined, the spheres and 
clumps may easily escape notice, even though they be present in 
hundreds in the field of the microscope. On standing they become 
more distinct, and they become obvious at the periphery of the drop, 
when they are still barely visible in the centre. In sufficiently viscid 
saliva the spheres and clumps are much distorted at the edge of the 
drop, and in still more viscid saliva most of them are drawn out into 
elongated masses. 

Acetic acid, ‘5 per cent. up to nearly glacial, makes the spheres and 
clumps very refractive and rather oily- looking. Glacial acetic acid 
causes them to swell up and become pale, and the clumps usually 
become vacuolated. Sodium hydrate causes them to swell up and 
disappear. 

When saliva containing spheres and clumps is allowed to stand, 
these bodies slowly settle, forming, as they do so, masses often of 
considerable size. The addition of an equal volume of 5 to 20 per cent. 
sodium chloride allows them to sink much more rapidly; they make 
a white, slightly adherent, but not viscid layer at the bottom of the 
vessel. 


On irrigating viscid saliva under a cover-slip, the fluid added mixes but 
slowly with the saliva, so that, instead of irrigating, it is sometimes better to 
mix a small drop of saliva with a small drop of the reagent, and to place a 
cover-slip on the mixture. Water causes the spheres and clumps to disappear, 
but up to a certain point they can again be made visible by acetic acid; 1 per 
cent. NaCl or Na,CO, makes the outlines of the bodies more distinct ; 1 per cent. 
osmic acid causes them to swell up and take a faint brown tint. Methylene- 
blue dissolved in Na,CO,, 1 per cent. stains them, but asa rule not very quickly. 
Picrocarmine, safranin, and other reagents stain them slowly. When saliva 
is mixed with one to two volumes of dilute neutral or alkaline salts, dilute or 


1 Eckhard, Ztschr. f. rat. Med., 1866, Bd. xxviii. S. 120, found the sympathetic saliva 
from the parotid g gland of the horse to be whitish and to contain fine particles. Schiff, 
**Lecons sur la digestion,” p. 298, found the same with the first drops of saliva secreted 
reflexly after a pause. The characters described were no doubt due toa precipitation of 
calcium salts in the saliva contained within the ducts. 


SUBSTANCES SECRETED IN SALIVA. 503 


strong acids, the spheres and clumps gradually disappear. In strong solutions 
of neutral salts (e.g. 20 per cent. sodium chloride), they may be kept for months 
at any rate. Strong alcohol and mercuric chloride cause them to shrink and 
make them irregularly granular. Flemming’s fluid turns many of them into 
vacuolated spheres, with sharp outline and a few distinct small granules. No 
mucous cells are seen in saliva after treatment with any of these reagents. 

In the submaxillary saliva of the cat, vacuolar and pale spheres are found, 
but not the larger clumps. 

Microscopical constituents in saliva have been described by Eckhard, 
Kiihne, and Heidenhain. The account I have given above differs in several 
points from theirs. 


The most obvious view to take of these microscopical constituents 
of saliva is, I think, that some of the mucous granules are turned bodily 
out of the alveolar cells, the fluid passing through the cells being 
insufficient to dissolve them; and that by swelling up or massing 
together they make the various forms of spheres and clumps which are 
seen. But although the mucous granules behave with some reagents 
very much as do the small spheres of saliva, and have in some states 
very much the same appearance, their behaviour with acetic acid is 
strikingly different. The mucous granules, on treatment with dilute 
acetic acid, swell up and burst like bubbles ;? the spheres in saliva, as we 
have seen, become refractive and obvious. Although it is possible that 
this difference may depend on differences in the surrounding fluids, it is 
sufficient to prevent more than a provisional acceptance of the view 
that the spheres of saliva are simply undissolved mucous granules. 


SUBSTANCES WHICH ARE OR WHICH MAY BE SECRETED IN SALIva.® 


In saliva obtained from mucous glands, the chief organic constituent 
is naturally mucin. Little is known with certainty of the varieties of 
mucin which exist. In mucous saliva, whilst most of the mucin is 
precipitated by acetic acid as a stringy lump, there is not infrequently 
a portion which is precipitated in fine particles, these making the fluid 
cloudy. A small quantity of proteid is also present, probably belonging 
to the class of globulins. 

In saliva obtained from albuminous glands the proteid constituents 
are globulin (or a body allied to globulin), alkali albuminate, and a 
small amount of serum albumin.+* 

In typical mucous saliva, diastatic ferment is either absent, or 
present in mere traces; in saliva from albuminous glands, the amount 
of diastatic ferment is variable and independent of the percentage of 
proteid, but in the saliva of any one gland the diastatic action increases 
with the percentage of proteid present. 

The salts are, so far as is known, the same in mucous and in 
albuminous saliva, although their percentage amount varies considerably 
in the saliva obtained from different glands. The bases found are 
sodium, potassium, calcium, and magnesium; the acids are hydrochloric 
acid, carbonic acid, phosphoric acid, and sulphuric acid. Sodium 
chloride is by far the largest constituent; after this comes usually 


1 Langley, Proc. Roy. Soc. London, 1886, vol. xi. p. 202. 

2 Langley, Journ. Physiol., Cambridge and London, 1889, vol. x. p. 433. 
3 See also article on ‘‘ Composition of Saliva,” p. 342. 

+ Kiihne, ‘‘ Lehrbuch. d. Physiol.,” 1866. 


504 THE SALIVARY GLANDS. 


sodium carbonate; calcium carbonate and calcium phosphate are kept 
in solution by the excess of carbonic acid, and precipitated as the gas 
escapes. 

Saliva yields to a vacuum about twenty vols. per cent. of carbonic 
acid, and small quantities of oxygen and nitrogen;! the carbonic acid, 
however, is all or nearly all combined with sodium carbonate to form 
sodium bicarbonate. 

In the saliva of man, potassium sulphocyanate is normally present.” 

The alkalinity of saliva depends upon the presence of sodium 


carbonate. In man and in the dog the percentage of this salt varies 


from 0:08 to 0-19 per cent. 

In disease? traces of other substances have been found in the saliva 
of man, for example, urea and leucine. In diabetes, lactic acid has been 
found in the saliva; the presence of sugar has been denied by most 
observers, but affirmed by some. In jaundice, saliva does not usually 
contain either bile acids or bile pigments, but in some instances traces 
are said to occur. In cases of poisoning with salts of mercury, lead, and 
some other metals, small quantities of the salts may be present in 
saliva; it is stated, however, that the salts of arsenic are not secreted by 
the salivary glands. 

An investigation into the character of the substances which can and 
which cannot be secreted by the salivary glands, would undoubtedly 
lead to interesting and valuable information. It is possible that, with 
bodies not acted on chemically, the size of the molecule is the determin- 
ing factor. A beginning of such inquiry, though not from this point of 
view, was made by Bernard.* He experimented on the secretion from 
the submaxillary and parotid glands of the dog, and on the parotid 
glands of the horse. He found that potassium iodide was very readily 
secreted, whilst neither sugar, ferrocyanide of potassium, nor lactate of 
iron was secreted by the salivary glands, though they were all secreted 
by the kidney. Iodide of iron, on the other hand, passed into the saliva. 

When lithium citrate is injected into the blood, the spectrum of 
lithium can be detected in the first drops of saliva secreted.2 And 
methylene-blue also passes into the saliva, but it does not appear to do 
so constantly. Sulphindigotate of soda, which is so readily secreted by 
the liver and kidney, is not secreted by the salivary glands;® after 
injecting large amounts into the blood, a small quantity may be found 
in the saliva, but there is no reason to believe that this is due to any 
cause other than diffusion. 


EFFECTS OF THE CRANIAL AND SYMPATHETIC NERVES ON THE 
Bioop FLow. 


The fundamental fact that the cranial nerve contains vaso-dilator 
fibres and the sympathetic vaso-constrictor fibres, has been already 
mentioned. If any salivary gland be exposed, it will be seen to flush on 


1 Pfliiger, Arch. 7. d. ges. Physiol., Bonn, 1868, Bd. i. S. 686. 

2 Gamgee, ‘‘ Physiological Chemistry,” vol. ii., from whom much of this paragraph 
is taken. 

° **Tecons de physiol. expérimentale,”’ 1856, Bd. ii. 

4 On injecting a large quantity of dextrose into the blood, I have found sugar in the 
saliva, and in quantity which is, I think, much too large to be accounted for by diffusion. 

5 Langley and Fletcher, Phil. Trans., London, 1889, vol. clxxx. p. 149. 

6 Eckhard, Beitr. z. Physiol. C. Ludwig, z. s. 70, Geburtst., Leipzig, 1887, S. 13. 


EFFECTS OF NERVES ON THE BLOOD FLOW. 505 


stimulating the cranial nerve, and to become pale on stimulating the 
sympathetic. 

The more detailed examination! of the blood flow through the gland 
has been made almost exclusively on the submaxillary gland of the dog. 
The blood flowing ordinarily from the vein is dark; on stimulating the 
chorda tympani, the blood flow increases rapidly for ten to twenty 
seconds, and then slowly decreases to normal; the blood itself becomes 
arterial in colour. The degree of the increase naturally varies, the flow 
may be five times as fast as the normal. In favourable cases the vein 
pulsates, and when it is cut the blood issues in jets, somewhat as from 
a small artery. Bernard gives the normal blood flow through the gland 
as about 5 c.c. in a minute; and this has been approximately the rate of 
flow in my own experiments, in which anesthetics were given. Von Frey 
found—presumably in very large dogs—the rate of blood flow through 
the gland to be much greater, about 12 c.c. ina minute. In y. Frey’s 
experiments, stimulation of the chorda for ten seconds caused the rate 
of blood flow to be 3 to 7 ec. in five seconds; the effect rapidly decreased 
on repeated stimulation ; the flow was diminished by curari. 


There are no complete observations on the changes in the gases of the 
blood as it passes through glands in rest and in activity, but some data are 
given by Bernard. 


According to Bidder,’ the maximal blood pressure in the vein, 
as the result of stimulation of the chorda tympani, is 37 mm. of 
mercury. 

On stimulating the sympathetic the blood becomes darker, and flows 
more and more slowly, the maximal effect being obtained in twenty to 
thirty seconds. 


It is doubtful whether the sympathetic completely stops the blood flow 
in the normal submaxillary gland ; it does so at times in an experiment, but 
this may be due to clotting occurring when the blood becomes slow. In the 
parotid the effect of the nerve appears to be greater. 


The latent period of both chorda and sympathetic varies from a 
barely perceptible time to several seconds; it depends upon the strength 
of the stimulus, the number of previous stimulations, and other con- 
ditions; but, generally speaking, the latent period is longer with the 
chorda than with the sympathetic. 

Both nerves have a rather long after-action. The maximal effect 
remains for ten to fifteen seconds, and the original rate of blood flow 
only recurs a minute or so after the end of the stimulation. The dura- 
tion of the after-action depends, up to a certain limit, upon the duration 
of the stimulus; and it appears to be greater with the chorda tympani 
than with the sympathetic. These points, however, have not received 
much attention. 

When both nerves are stimulated simultaneously with maximal 
currents, the sympathetic gets the upper hand during the stimulation, 

1 Bernard, Journ. de l’anat. et physiol., ete., Paris, 1858, tome i. pp. 238, 649 (reprints 
from Compt. rend. Acad. d. sc., Paris, of the same year) ; ‘‘Legons sur les propriétés physiol. 
ete.,” 1859; v. Frey, Arb. a. d. physiol. Anst. zu Leipzig, 1877, Bd. xi. S. 89; Langley, 
Journ. Physiol., Cambridge and London, 1889, vol. x. p. 316. 


2 Cf. ‘‘ La chaleur animale,” 1876, p. 179. 
3 Arch. f. Anat. u. Physiol., Leipzig, 1866, S. 339. 


506 THE SALIVARY GLANDS. 


and anemia of the gland is produced as if the sympathetic alone were 
being stimulated. Von Frey, using brief stimuli—usually lasting about 
ten seconds—observed that the after-action was that of the chorda 
tympani, and in some cases the increase of blood flow after the stimula- 
tion appeared to be as great as if the chorda alone had been stimu- 
lated. 

When, however, the sympathetic is stimulated with weak currents, 
and the chorda tympani with strong currents, there is, within certaim 
limits, an algebraical summation of effects. And the constriction pro- 
duced by a weak stimulation of the sympathetic may be more or less 
annulled by a strong stimulation of the chorda. 


Mutua. EFFECTS OF THE CRANIAL AND SYMPATHETIC NERVES 
UPON SECRETION. 


We have already mentioned, under the head of the augmented 
secretion (p. 496), the effect on the sympathetic saliva of a previous 
brief stimulation of the cerebral nerve. 

When the chorda tympani and the sympathetic nerve in the cat 
are stimulated simultaneously with minimal currents of not too long 
duration, the amount of saliva obtained is greater than that which is 
obtained from either nerve alone! In the dog the same effect may also 
be seen; at any rate, if the gland is in a state to allow the sympathetic 
to produce an augmented secretion. 

As the currents are increased in strength, the amount of the saliva 
obtained by simultaneous stimulation becomes rapidly less and less in 
excess of that obtained by stimulating the chorda alone. And with a 
very moderate strength of sympathetic ae hae the amount of saliva 
obtained by simultaneous stimulation falls below, and it may be very 
considerably below, that which is afforded by stimulation of the chorda 
by itself. The secretion is rapid for five or ten seconds, and then 
speedily becomes slow. The retarding effect of the sympathetic we may 
reasonably attribute to the diminution in the blood supply to the 
gland which it brings about. 

In the parotid gland of the cat similar effects are seen on excitation 
of the sympathetic and of Jacobson’s nerve. The sympathetic nerve in 
the dog has a very marked retarding action upon the flow of saliva pro- 
duced by Jacobson’s nerve from the parotid gland, and it may stop the 
flow altogether (cf. also p. 498). 

Prolonged stimulation of the sympathetic reduces the irritability of 
the gland, so that, on subsequent stimulation of the chorda tympani, the 
saliva only appears after a long latent period, and but gradually acquires 
its normal rate of flow. 


Czermak? was the first to call attention to the retarding action of the 
sympathetic upon the chorda secretion. He stated that in the dog, the 
sympathetic stopped the chorda secretion, and produced a condition of the 
gland of such nature that it did not for some time respond to stimulation of 
the chorda tympani. He referred the action to inhibitory fibres, which he 
believed to be present in the sympathetic. Eckhard® considered that the 


1 Langley, Journ. Physiol., Cambridge and London, 1878, vol. i. p. 102. 
2 Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1857, Bd. xxv. S. 3. 
® Beitr. z. Anat. u. Physiol. (Eckhard), Giessen, 1860, Bd. ii. S. 95. 


CRANIAL AND SYMPATHETIC NERVES. 507 


retarding effect of the sympathetic was due to the secretion produced by it 
being very thick and viscid, and in consequence blocking up the ducts. 
Heidenhain ! attributed the action of the sympathetic to the lack of oxygen 
caused by the diminished blood supply. 


The effects on the percentage composition of chorda saliva, caused by 
first obtaining a considerable quantity of sympathetic saliva, and vice 
versd, were noted by Heidenhain.? He found that protracted stimulation 
of either nerve diminishes the percentage of organic substance in the 
secretion subsequently obtained by stimulating the other nerve. 


(a) Thus stimulation of sympathetic for two hours—0°65 grm. of saliva 
secreted, containing 5°9 per cent. solids. 

The chorda tympani was then stimulated for two hours. 

Stimulation of sympathetic for about one and a quarter hours—0-54 grm. 
saliva, containing 2°4 per cent. of solids. 

(6) Stimulation of the sympathetic for six hours reduced the percentage of 
the chorda saliva from 2°4 to 1-0. 


Since the organic substance in the saliva comes in the main at any 
rate—entirely, so far as we know—from the substance stored up in the 
gland-cells, the facts given by Heidenhain show that the secretion 
obtained from the two nerves arises in part at least from the same gland- 
cells. 


On microscopic examination of the submaxillary gland of the dog, 
after several hours’ excitation, either of the chorda tympani or of the 
sympathetic, the alveoli are found to be changed to a very unequal degree, a 
few having still the ordinary resting characters. This renders it probable that 
the secreting fibres are not equally distributed to all the alveoli. 


Since the sympathetic saliva contains a higher percentage of organic 
substance than chorda saliva, we should expect that simultaneous stimu- 
lation of the sympathetic and of the chorda tympani would give a saliva 
containing a less percentage of organic substance than sympathetic 
saliva, and a greater percentage than chorda saliva; and this is the 
case. 

Heidenhain has shown that the chorda saliva which is obtained 
shortly after stimulating the sympathetic has a higher percentage of 
organic substance than that obtained before such stimulation. The 
saliva, however, soon becomes normal, usually after 2 to 3 c.c. have 
been secreted. The after-effect of sympathetic stimulation is com- 
parable to the after-action caused by strong stimulation of the chorda 
tympani, of which we have already spoken (p. 505). 

We have dealt chiefly with the submaxillary gland, but the mutual 
relations of the cranial and sympathetic nerves are essentially the same 
in other salivary glands, including the parotid of the dog, in which the 
sympathetic nerve by itself commonly gives no flow of saliva. 


The following results, taken from experiments by Heidenhain, will serve 
to illustrate some points regarding the saliva secreted by the parotid gland 
when both the sympathetic and Jacobson’s nerve are stimulated. 


1 Hermann’s ‘‘ Handbuch,” Bd. v. 8S. 46. 
2 Stud. d. physiol. Inst. zw Breslau, Leipzig, 1868, S. 71. 


508 THE SALIVARY GLANDS. 


EXpERIMENT 1.—The Parotid Gland of the Dog. 


St : : ; ake +yq| Percentage of 7 
| Saliva obtained by Stimulating— Durpuonigl Gout Fea es i Onanic | P orcas of 
| 
| | 
Jacobson’s nerve. . 18 min. 3°11 grms. 0°76 | 0°26 
| Jacobson’s nerve and the 
sympathetic ; : 30 min. 3°63 grms. 141 | 0°32 


Experiment 2.—Zhe Parotid Gland of the Rabbit.? 


In this experiment pilocarpine was injected, and a sample of the saliva 
collected. The cervical sympathetic was then stimulated ; during the stimula- 
tion the secretion became slower until it stopped ; on its cessation the stimula- 
tion was also stopped. After a short time the flow began again ; when about 
three drops had been secreted the sympathetic was again stimulated, and so 
on, till a second sample of saliva was collected. 


= Percentage of 

cn : Rate of Secre- | = Percentage of 
Saliva obtained from * ceS Organic 
tion per Minute. | Substance. Salts. 

Pilocarpine . : - 0°22 c.c. 0°39 0°85 
| 

Pilocarpine and sympa- 

thetic stimulation . 0°062 cc. | 3°62 | 0°75 


EFFECT OF VARIATIONS IN THE AMOUNT AND QUALITY OF THE BLOOD* 
SUPPLIED TO A GLAND, UPON THE AMOUNT AND PERCENTAGE 
COMPOSITION OF THE SALIVA SECRETED. 


In order to form a satisfactory theory of the action of secretory 
nerves, it is of the greatest importance to know how far variations in 
the amount and character of the blood flowing through the gland affect 
the amount and character of the saliva. Our information on this point 
is unfortunately still vague in many respects. 

Certain broad facts can be readily observed by compressing the 
carotid artery on one side, after tying the carotid artery on the other 
side, and the subclavian arteries on both. The gland-veins are cut, so 
that the amount of blood flowing through the gland can be roughly 
determined; and the chorda tympani is stimulated during different 
degrees of compression of the carotid. 

When the carotid is compressed to a moderate extent, the chorda on 
stimulation will not cause so much increase in the blood flow through 
the gland as it otherwise would, but it will nevertheless cause a con- 
siderable increase, and the blood will issue from the vein of an arterial 
colour. In such case, according to Heidenhain, the amount of saliva 
obtained by a given stimulus will be of normal amount. 


1 Heidenhain, Arch. f. d. ges. Physiol., Bonn, 1878, Bd. xvii. 8. 31. 

? Heidenhain, op. cit., S. 40. 

* Heidenhain (Stud. d. physiol. Inst. zu Breslau, Leipzig, S. 98) appears to refer to an 
increase of blood flow above that occurring with partially compressed carotid, and not to an 
increase above the normal blood flow. 


EFFECT OF VARIATIONS INTHE BLOOD SUPPLY. 509 


Ata certain further stage of compression of the carotid, stimulation 
of the chorda will still cause an increase of blood flow from the gland, 
but the blood issuing from it, instead of being of an arterial colour, will 
be of a venous colour. In this case Heidenhain finds that the amount 
of saliva obtained by a given stimulus will be less than normal. 

When the artery is so far compressed that little blood flows through 
the gland, and the chorda causes no increase in it, there is naturally a 
great decrease in the amount of saliva obtained by a given stimulus. 
If the stimulus last about a minute only, the decrease is in fact nearly 
as great as if the blood supply be entirely cut off. On allowimg the 
blood to flow again through the gland, the chorda saliva does not at 
once attain its normal amount. Brief closure of the artery causes more 
or less protracted diminution in the efficiency of the chorda; it may be 
noted that the vaso-dilator effect of the chorda recovers more quickly 
than its secretory effect. 


The following example, taken from Heidenhain,! may be given to illustrate 
some of the points mentioned above :—Dog, arteries to head tied, except left 
carotid. Wharton’s duct connected with a tube graduated in millimetres. 
Gland-vein opened. The chorda tympani was stimulated for one minute, and 
the rise in millimetres of the saliva in the tube was noted each five seconds. 

Saliva flow. —0, 20, 70, 50, 55, 45, 36, 30, 27, 29, 30, 28 = 410. 

The artery was then clamped for five minutes ; during the last minute the 
chorda was stimulated, the blood flow from the vein was very slight. 

Saliva jlow.—0, 0, 21, 32, 33, 17, 14, 8, 6, 7, 2, 2=142. 

The carotid was left unclamped for eight minutes, then clamped for one 
minute, during which the chorda was stimulated. 

Saliva flow.—0, 0, 0, 2, 4, 6, 5, 5, 5, 4, 5, 4= 40. 

The carotid was unclamped, but the stimulus kept up for two minutes. 
The blood flow from the vein was moderately increased. The saliva rose 


69 and 51 mm. 
The carotid remaining unclamped, the chorda was stimulated during the 


third minute. It caused a rise of saliva of 203 mm. 


The effect of diminished blood supply upon the percentage composition 
of saliva has not been very fully investigated. But Eckhard? states that 
ligature of the veins of the submaxillary gland does not cause chorda 
saliva to alter its character and become like sympathetic saliva. And, 
according to Heidenhain,’ diminution of the blood supply by compression 
of the carotid does not cause an appreciable increase in the percentage of 
solids in saliva. 

Heidenhain’s experiments undoubtedly show that, in certain circum- 
stances, a diminution of the blood supply to the gland has no considerable 
influence upon the percentage of organic substance in the saliva, obtained 
by stimulating the cranial nerve. But this does not seem to me to hold 
in all circumstances, for, in some observations on the submaxillary 
gland of the dog, made by Fletcher and myself, bleeding the animal, 
whilst decreasing the rate of the secretion of saliva produced by 
pilocarpine, largely increased the percentage of organic substance in the 
saliva. 


1 Stud. d. physiol. Inst. zu Breslau, Leipzig, S. 93. 

2 Beitr. z. Anat. u. Physiol. (Eckhard), Giessen, 1860, Bd. ii. S. 212. 
3 Arch. f. d. ges. Physiol., Bonn, 1878, Bd. xvii. S. 33, 43. 

4 Phil. Trans., London, 1889, vol. clxxx. p. 131. 


510 THE SALIVARY GLANDS. 


There are no experiments which show definitely what is the effect on 
the percentage composition of saliva of a decrease of blood supply due 
to simple constriction of the vessels. When the cranial nerve is 
stimulated during compression of the carotid artery, the blood flowing 
through the gland flows through dilated vessels. When the diminution 
in blood supply is brought about by stimulating a vaso-constrictor 
nerve, the blood flowing through the gland flows through constricted 
vessels. It is probable that, in the former case, fluid passes more 
readily through the vessel walls; hence, with the same amount of 
organic substance secreted in the two cases, one saliva might have a 
low and the other a high percentage of organic substance. 

Changes in the amount and character of the saliva may, however, 
be produced by variations in the character of the blood. The injection 
of a considerable quantity of dilute salt solution, such as 0:2 per cent., leads 
to a considerable increase in the rate of secretion of saliva, whether this 
is set up by stimulating the chorda tympani or by injecting small 
quantities of pilocarpine. Up to a certain point the percentage of 
salts increases in the normal manner; beyond this the percentage ceases 
to increase and may fall. An increase in rate may also be produced by in- 
jecting into the blood 100 ¢.c. to 250 c.c. of stronger solution (as 2 per cent.) 
of sodium chloride or sodium carbonate. Probably this amount leads to 
the passage of water from the tissues, and so increases the volume of the 
blood. The injection may cause an increase in the percentage of salts. 
Injection of strong salt solution into the blood, in quantity sufficient to 
increase the percentage of sodium chloride in the serum, was found by 
Novi2 to increase the percentage of the salt in submaxillary saliva; 
though never up to thatin the serum. When a certain amount of strong 
salt solution (20 per cent.) is injected, the gland becomes cedematous, 
and neither placing acids on the tongue (Novi), nor stimulating the 
chorda tympani, nor injecting pilocarpine (Langley and Fletcher), will 
cause a secretion. 


RELATION OF SECRETION TO THE FLOW or LYMPH. 


We know very little with regard to the flow of lymph from the 
glands in various conditions. The lymph vessels leave the submaxillary 
gland at the hilus. If the lymph could be collected and analysed, it 
would give information very much needed with regard to the secretory 
activity. Heidenhain,? who has paid some attention to the subject, 
appears only to have noticed whether cedema of the gland was produced 
or not, but it is manifest that if the lymph vessels were large there 
might be very great increase in the lymph flow without cedema. 

Heidenhain* considers that there is no increase in lymph flow from 
the gland during stimulation of the chorda, either before or after giving 
atropine. Supposing, then, that atropine does not act on the vessel wall, 
so as to hinder the passage of fluid through it, it would follow that fluid 
passes from the vessels in increasing amount, as an increasing amount 
of saliva is secreted by the gland. In other words, it would follow that 
there is in rest a certain slight constant formation of lymph, and that, 


1 Cf. Langley and Fletcher, op. cit. 

2 Arch. f. Anat. u. Physiol., Leipzig, 1888, Physiol. Abth., S. 403. 
3 Arch. f. d. ges. Physiol., Bonn, 1874, Bd. ix. S. 346. 

4 Hermann’s ‘‘ Handbuch,” 1880, Bd. i. Th. 1, 8. 73. 


THE SECRETORY PRESSURE. 511 


when the gland secretes, an additional amount is formed exactly equal 
to that of the fluid in the saliva secreted,—a conclusion which it is not 
easy to accept. 

In two conditions cedema of the gland is obtained: First, when 
dilute acid (0°5 per cent. HCl) or an alkaline salt (5 per cent. Na,CO,) 
is injected into the gland duct.1_ In this case, cedema is slowly pro- 
duced; rapidly, however, if the chorda tympani be stimulated, though 
no secretion follows. There can be little hesitation in attributing this 
to the injury inflicted on the walls of the small vessels; for damage of 
the vessels, as we know, largely increases the amount of the lymph 
formed in any given condition. Secondly, when there is a considerable 
resistance to the flow of saliva from the duct. On continued stimulation 
of the chorda in such cases, the lobules become separated by a mucous 
fluid, and there is great cedema. At first this fluid consists simply of 
filtered saliva; later, probably, lymph is added, partly in consequence of 
a direct injury to the vessels, and partly, as suggested by Heidenhain, in 
consequence of pressure on the vein. 


THE SECRETORY PRESSURE. 


Ludwig? was the first to show, by experiment on the submaxillary 
gland of the dog, that the secretory pressure may overpass considerably 
the blood pressure. Thus in one case he obtained a pressure of 190 mm. 
of mercury from the saliva caused to flow by stimulating the chordo- 
lingual nerve, although the blood pressure in the carotid artery was only 
112 mm. of mercury. Since that time considerably higher pressures 
have been obtained from chorda saliva; the maximum pressure observ- 
able in any one species is, broadly speaking, the greater, the larger the 
individual. 

On connecting Wharton’s duct with a mercurial manometer, and 
stimulating the chorda tympani, the pressure rises at first rapidly, then 
more and more slowly ; when the maximum pressure is attained, a 
cessation of the stimulus is followed by a fall of pressure, due to filtra- 
tion taking place between the cells of the ducts and of the alveoli. 
When the observation is at all frequently repeated, the lobules of the 
gland become separated by mucous fluid, the pressure attained becomes 
less, and the irritability of the gland greatly decreases. 

In the parotid gland of the dog, the observed secretory pressure is 
less than in the submaxillary gland, usually being 100 to 130 mm. of 
mercury, but the difference is probably due to the limpidity of the 
parotid saliva, which allows a more rapid filtration. 

The pressure of the sympathetic secretion may also exceed that 
of arterial blood. In experimenting with a mercurial manometer, the 
pressure should be raised artificially to about 150 mm. of mercury 
during the first stimulation of the sympathetic, the connection of the 
manometer with Wharton’s duct clamped for about thirty seconds, 
and then unclamped and the sympathetic again stimulated. Heiden- 
hain,? in an experiment on the submaxillary gland of a dog, found 
that the sympathetic saliva was secreted at a pressure of 150 to 160 
mm., whilst the pressure of the chorda saliva was 250 to 270 mm. 


1 Gianuzzi, Ber. d. k. stéichs. Gesellsch. d. Wissensch., 1865. 
2 Ztschr. f. rat. Med., 1851, N. F., Bd. i. S. 271. 
° Stud. d. physiol. Inst. zu Breslau, Leipzig, S. 69. 


512 THE SALIVARY GLANDS. 


It may, however, be doubted whether there is such a difference in the 
maximum pressure. In the observations I have made on the point, 
stimulating alternately the chorda tympani and the sympathetic, the 
sympathetic has given a perceptible though slight and brief rise of 
pressure at approximately the maximum pressure obtainable from the 
chorda tympani. 


REFLEX INHIBITION OF THE SALIVARY SECRETION. 


During the progress of secretion, a certain decrease in the rate of 
flow, or even a cessation, may be caused by stimulation of afferent 
nerves. Such an effect might be due—to select the most probable 
causes—either to an inhibition of the central secretory centre, or to a 
constriction of the blood vessels of the gland. The experiments have 
not, however, been directed to an accurate determination of the method 
of production of reflex inhibition. 

Pawlow!? states that the slow secretion induced by partial dyspnea, 
or by curari, is decreased or temporarily stopped by stimulation of the 
sciatic for one or two minutes with a particular strength of current, or 
by exposure of the abdominal viscera. The experiments given can 
hardly be considered to be conclusive, and Buff? finds that, quite apart 
from stimulation, the secretion occurring in the conditions of Pawlow’s 
experiments is not itself constant in rate. 


ACTION OF ALKALOIDS UPON THE SALIVARY GLANDS. 


There are obviously a number of ways in which a substance intro- 
duced into the blood might cause a secretion of saliva. It might 
stimulate the peripheral endings of sensory nerves and produce a reflex 
secretion; it might stimulate some part of the central nervous system, 
the connections of the visceral nerve-fibres with the local nerve-cells, 
the nerve-cells directly, the nerve-endings in the gland, or finally the 
gland-cells directly. Of several of these modes of action we have no 
certain example. We shall confine our attention to those alkaloids, 
the effects of which have most served as a basis of physiological 
deduction.? 

Atropine.—Atropine arrests the normal secretion from the glands 
of the mouth, nose, and pharnyx, so that the whole mucous membrane 
becomes dry. The arrest is due to a paralysis of the cranial secretory 
nerves, the strongest stimulation of them no longer causing a secretion.* 
In the dog, 10 to 15 mgrms. of atropine, when injected into a vein, pro- 
duce the paralysis; in the cat, 3 to 5 mgrms. are sufficient. Considerably 
smaller doses than these reduce to very small limits the secretory power 
of the nerves; hence, in determining the minimal amount of atropine 
required to produce paralysis, it is advisable to stimulate the nerve for 
a minute or more, and to repeat this after a few minutes’ interval. 

The sympathetic nerve is either not paralysed at all, or only by a 


1 Arch. f. d. ges. Physiol., Bonn, 1878, Bd. xvi. S. 272 (experiments made on the sub- 
maxillary gland of the dog). 

2 Beitr. z. Anat. u. Physiol. (Eckhard), Giessen, 1888, Bd. xii. S. 3. 

3 A few only of the original papers dealing with this subject can be given here ; fuller 
references will be found in treatises on pharmacology. 

4 Keuchel, ‘‘Das Atropin und die Hemmungsnerven,” Dorpat, 1868; Heidenhain, 
Arch. f. d. ges. Physiol., Bonn, 1872, Bd. v. S. 309. 


PILOCARPINE AND MUSCARINE. 513 


comparatively large dose of atropine." In the dog more than 100 
megrms. may be injected into a vein, and still secretion will be obtained 
from the submaxillary gland by stimulating the cervical sympathetic. 
In the cat this nerve ceases to cause a secretion after about 30 mgrms. 
of atropine have been given.? 

The point of action of atropine is the termination of the nerve-fibres 
around the gland-cells. There are several facts which show this. We 
may mention the following :—In the case of the submaxillary gland, 
when a dose of atropine has been given just sufficient to paralyse the 
chorda tympani, no secretion is obtained by stimulating peripherally of 
the (true) submaxillary ganglion; ae, the postganglionic nerve-fibres 
cause no secretion. Atropine appled directly to nerve-fibres—whether 
preganglionic or postganghonic—in their course towards a tissue, does 
not paralyse them. The paralysis produced by it must then be either 
one of nerve-endings or of gland-cells. But in the case we are consider- 
ing the gland-cells are not paralysed, since they are at once set secreting 
by stimulating the cervical sympathetic. Hence we conclude that 
atropine acts upon and paralyses the nerve-endings of the postganglionic 
secretory fibres of the chorda tympani. And we may conclude, further, 
that in other cases in which atropine paralyses secretory nerves, it has 
this effect in consequence of an action upon the nerve-endings in the 
gland. 


The exact method of action of atropine we can only guess at; we might 
suppose, either that it annuls the conductivity of the nerve-endings, or that 
it causes a retraction of the terminal filaments, in the manner suggested by 
Duval and others for the processes of nerve-cells in general, so that nervous 
impulses can no longer pass from the nerve-endings to the gland-cells. 


Atropine does not paralyse the vaso-dilator fibres which accompany 
the cranial secretory nerves. This was first shown by Heidenhain ? in 
the case of the chorda tympani of the dog. It is true that, when large 
doses of atropine are given, both vaso-dilator ‘and vaso-constrictor elandular 
nerves produce less effect than normal, but there is nothing to show that 
this action is in any way specific. 

Pilocarpine and muscarine.— Both pilocarpine and muscarine pro- 
duce copious and prolonged secretion, when given in very small quantity ; 
for example, when | or 2 mgrms. are injected into the blood The 
secretion when it slackens is nga by a further dose of the alkaloid, 
so that the flow of saliva can be kept up ‘for a very long time, apparently 
indefinitely. A large dose is not required in order. to produce the 
maximum rate of Fc, its effect is rather to increase the duration of the 
flow. The saliva obtained is lke that produced by stimulating the 
cerebral nerve, and the secretion is accompanied by a great dilation of 
the vessels of the gland. 

The secretion to which these alkaloids give rise from the submaxillary 
gland is unaffected by section of the chorda tympani, or by extirpation 
of the superior cervical ganglion ; it occurs after the connections of the 
chorda tympani with the local nerve-cells have been paralysed by 


1 Heidenhain, op. cit. 

* Langley, Journ. Physiol., Cambridge, 1878, vol. i. p. 98. 

° Op. cit., supra. 

4 The chief features of the action of muscarine were described, ‘‘ Das Muscarin,” Leipzig, 
by Schmiedeberg u. Koppe in 1869. 


VOL. I.—33 


514 THE SALIVARY GLANDS. 


nicotine, and also after degeneration of the chorda tympani itself (ef. 
p- 519). The alkaloids therefore stimulate some peripheral structure. 
And as in the case of atropine, so with pilocarpine and muscarine, it is 
hardly open to doubt that the nerve-endings of the postganglionic fibres 
are the points of attack. The nerve-endings of the sympathetic nerve- 
fibres, on the other hand, are not stimulated by pilocarpine or by 
muscarine. 

Stimulation of the chorda tympani during the pilocarpine secretion ! 
produces in most circumstances an increase in the rate of flow, but when 
the secretion is as rapid, or nearly as rapid, as the alkaloid is capable 
of producing, the chorda has little or no effect. Further, after large 
doses of pilocarpine have been given, the chorda has also little or no 
effect ; in the latter case, the apparent paralysing action may be due 
to the presence of more than one alkaloid in what passes for pilo- 
carpine. 

Stimulation of the sympathetic during the pilocarpine secretion 
causes a primary increase in rate, like that of the augmented secretion ; 
after this there is a slowing, and if the stimulation be strong, there may 
be a complete cessation of the flow. The slowing effect is less in the 
submaxillary gland of the cat than in that of the dog, and less in the 
submaxillary of the dog than in the parotid of the dog. 


The effect of the sympathetic in the last two cases is seen in the following 
extract from an experiment : ? — 


Doc.—FPilocarpine Nitrate injected—Rise of Saliva in Tubes connected with the 
Duets of the Submaxillary and Parotid Glands, taken every thirty seconds, 
in millimetres. 


Submaxillary  . 25 
5 


54.» 9 81-02. Ay Ole OenOhyaly 235i oor ee 
Parotid 9 


2 »..0 9-0 + 0 Ore 0) RO. OUSO) OO Sie ae acs 


Oe 
stim. sympathetic 


The mutual antagonism* of atropine and pilocarpine (or mus- 
carine).—If atropine, in quantity just sufficient to paralyse the chorda 
tympani, be injected into a vein of an animal, subsequent injection of 
pulocarpine or muscarine may or may not cause secretion. In many 
cases, aS the amount of the alkaloid given is increased, death ensues, 
whilst the secretory nerves are still paralysed by atropine. 

There are two methods by which the antagonistic action of two 
poisons on the salivary glands may be observed more satisfactorily 
than by injecting them both into the general circulation. The one is 
to inject the weaker poison in such a way that it passes through the 
vessels of the gland without entering the general circulation. The 
other method is to inject a small quantity of a rather strong solution 
of the weaker poison into the gland duct. In either case, the stronger 
poison is injected into the general circulation. 


1 Langley, Jowrn. Anat. and Physiol., London, 1876, vol. xi. p. 173 ; Journ. Physiol., 
Cambridge and London, 1878, vol. i. p. 339 ; Gley, Arch. de physiol. norm. et path., Paris, 
1889, p. 151. 

= ee Journ. Physiol., Cambridge and London, 1889, vol. x. p. 826. 

3 For the action of physostigmine and its antagonistic action on atropine, cf. Heidenhain, 
Arch. f. d. ges. Physiol., Bonn, 1872, Bd. v. S. 309, and 1874, Bd. ix. S. 335. For the 
mutual antagonism of poisons in general, and especially as regards muscarine and atropine, 
cf. Prévost, Arch. de physiol. norm. et path., Paris, 1877, p. 801. 


NICOTINE. 515 


Ihave tried both methods! in observations on the effects of 
pilocarpine and atropine upon the submaxillary gland of the cat and 
dog. The latter method is much simpler, and seems to me better. An 
experiment, briefly stated, is as follows. A paralysing dose of atropine 
is injected into a body vein. A cannula filled with a 2 to 4 per cent. 
solution of pilocarpine nitrate is tied into Wharton’s duct, and 0:1 to 0:25 
per cent. of the solution driven into the gland. This causes a secretion 
of saliva and great increase of blood flow, lasting several minutes, but 
steadily lessening in rate. During the flow of saliva the chorda 
tympani becomes again irritable, and may remain so for a short time 
after pilocarpine has ceased to produce a secretion. As the pilocarpine 
is carried out of the gland by the secretion, by the blood, and by the 
lymph, the atropine continually flowing to the gland in the blood again 
acquires the upper hand, and the nerve- endings become again paralysed. 
With renewed injection of pilocarpine there is renewed transient secre- 
tion and renewed transient irritability of the chorda tympani. And 
the paralysis and recovery may be repeated many times in an hour. 
It is, however, to be noticed, that if more than the minimal dose of 
atropine be given, more than one injection of pilocarpine may be required. 


Although piiocarpine can instantaneously restore some degree of activity to 
the chorda tympani which has been paralysed by atropine, yet the activity is 
always considerably less than normal. 

In the cat, when the cervical sympathetic has been paralysed by atropine, 
its activity can be restored by injecting pilocarpine into the duct, although 
pilocarpine does not stimulate the secretory nerve endings of the sympathetic. 


Nicotine.—Nicotine causes a brief flow of saliva, followed by a 
temporary paralysis of the cranial and sympathetic fibres 2 up to their 
connections with the peripheral ganglia? We have already described the 
main features of this paralysis in connection with the chorda tympani, 
and in connection with the sympathetic (p. 480). In all the mammals 
which have been experimented on, small doses of nicotine readily pro- 
duce excitatory effects, but the amount required to paralyse the secretory 
and vasomotor preganglionic fibres varies widely in different cases. 
Moreover, the minimal amount required to produce paralysis is not 
precisely the same for fibres of different origin, or for fibres of similar 
origin but different function. In the rabbit and cat the differences are 
not great, the amount required varying from about 5 to about 10 mgrms. 
In these animals about 10 mgrms. of nicotine injected into the blood 
will cause a paralysis of preganglionic fibres lasting about fifteen 
minutes. In the dog, 30 to 40 mgrms. have a similar effect on the chorda 
tympani, in so far that, usually, stimulation of the chorda for about twenty 
seconds causes no secretion; but in some cases, at any rate, and even 
after larger doses, more protracted stimulation of the chorda induces 
gradually an active and protracted secretion, continuing for some time 
after the cessation of the stimulus. And very large doses may be 
given to a dog without paralysing completely the cervical sympathetic. 


1 Journ. Anat. and Physiol., London, 1876, vol. xi. p. 173 ; Journ. Physiol., Cam- 
bridge and London, 1878, vol. i. p. 339 ; 1880, vol. iii. p: 2.. .Hor ‘method of injecting into 
the gland arteries, of. Heidenhain, op. cit., 1874. 

2 Heidenhain, "Arch. f. d. ges. Physiol., Bonn, 18725 Bas vy. S236: 

3 Langley and Dickinson, Proc. Roy. Soc. London, 1889, vol. xvi. p. 423 ; Langley, 
Journ. Physiol., Cambridge and London, 1890, vol. xi. p. 123. 

+ Repeated doses have a tendency to cause in the dog a continuous secretion, 


516 THE SALIVARY GLANDS. 


On the hypothesis that nicotine causes a contraction of the terminal 
fibrils of the chorda tympani, we might suppose that protracted stimulation 
leads to a slow gradual extension of the terminal fibrils, so that nervous 
impulses passing down the chorda tympani can again set up impulses in the 
peripheral nerve-cells. 


FORMATION OF HEAT IN THE SUBMAXILLARY GLAND. 


The rapid flow of saliva caused by stimulating the chorda tympani 
suggested, not unnaturally, that a considerable formation of heat must 
take place in the submaxillary gland. Ludwig and Spiess,! using thermo- 
electric junctions, and Ludwig,? using thermometers specially designed, 
brought experimental proof that in the dog this was in fact the case. 

Ludwig and Spiess placed one junction im the carotid artery, 
arranged as in the method of determining lateral blood pressure, so 
that the actual junction was, they said, in the full blood stream. The 
other junction was placed in a cannula connected with Wharton’s 
duct, and apparently on the same side as that of the carotid taken. 
With a moderate rate of secretion they found the saliva to be about 
1° C. warmer than the blood in the carotid. 

Ludwig placed one thermometer in the carotid near its origin, and 
another in the course of a cannula connected with Wharton’s duct of the 
opposite side. He states that there was in no case clotting in the 
carotid, but there does not seem to have been a flow of blood around the 
bulb of the thermometer. The room was kept at a temperature not 
less than 24° C. The saliva was found to be constantly of a higher 
temperature than the blood. The extent of this varied in different 
experiments, and, generally speaking, was greater the faster the secretion. 
The maximum difference found was 1°°6 C., the temperature of the saliva 
in this case being 41°:2C., the rate of secretion 0°5 c.c. in 5°5 seconds. 
Ludwig gives also three experiments upon the respective temperatures of 
the blood in the carotid artery, of the blood issuing from the gland vein, 
and of the saliva. As a rule, the temperature of the venous blood was 
below that of the carotid blood, but occasionally it was slightly greater 
than that of carotid blood or of saliva. For example,in one case the 
temperature of the blood in the carotid was 39°1C., that of the saliva 
39°°3 C., and that of the venous blood 39°:4 C. 

The proof of an appreciable formation of heat during secretion 
appeared complete when Heidenhain? observed by the thermo-electric 
method that the temperature of the gland was often higher than that 
of the carotid blood, the difference in favour of the gland being still 
greater on stimulation of the sympathetic; and when Morat,* by the 
same method, obtained a rise of temperature in the submaxillary gland 
of the dog, on stimulating the sympathetic both after bleeding the 
animal to death and during temporary ligature of the carotid, sub- 
clavian, and vertebral arteries. 


Bernard ® plunged one thermo-electric junction needle in each gland, and 
found that stimulation of the chorda tympani caused a rise of temperature, and 


1 Sitzungsh. d. k. Akad. d. Wissensch., Wien, 1857, Bd. xxv. S. 584; reprinted in 
Ztschr. f. rat. Med., 1858, N. F., Bd. ii. S. 361. 

2 Wien. med. Wehnschr., 1860, S. 433 and 449. 

3 Stud. d. physiol. Inst. zu Breslau, Leipzig, 1868, Heft 4, S. 110. 

4 Arch. de physiol. norm. et path., Paris, 1893, p. 285. 

5 «*Ta chaleur animale,” Paris, 1876, p. 325. 


ELECTRICAL CHANGES IN THE GLANDS. SEY 


stimulation of the sympathetic caused a fall of temperature in the gland of the 
same side. He concluded that calorific nerve-fibres are present in the chorda 
tympani, and frigorific nerve-fibres in the sympathetic; but there is nothing 
in the account to show that the results were not due simply to a variation in 
the blood supply. 


These results till recently passed unquestioned. But Bayliss and 
Hill; on testing them, both by the thermo-electric and the thermometric 
methods, never found the chorda saliva to be warmer than the arterial 
blood. Their experiments differed in some points of method from 
Ludwig’s. On one of these they consider the difference in result de- 
pends. The thermo-electric junction or the thermometer was pushed up 
the femoral artery into the aorta, so that it was exposed to the full 
current of blood. Bayliss and Hill consider that in Ludwig’s experiment 
the temperature observed was less than the real temperature of arterial 
blood, so that, on stimulating the chorda tympani, the saliva secreted, 
though of a higher temperature than that recorded for the blood, was 
not of a higher temperature than that of the blood actually supplied to 
the gland.2 And they came to the conclusion that no formation of heat 
in the submaxillary gland can be determined directly by any known 
method of measuring variations in temperature. 

Supposing for a moment that this conclusion is correct, it does not 
of course mean that no heat is formed in the gland during secretion, but 
simply that the heat—undoubtedly set free by the chemical changes—is 
insufficient to cause an appreciable rise of temperature in the considerable 
mass made up of the saliva, the gland, and the blood flowing through the 
gland. But the main question can hardly be regarded as settled. For 
the tissues in the neighbourhood of the gland artery and of the duct are 
—at any rate, after placing a cannula in the duct and preparing the 
chorda tympani—at a lower temperature than the aortic blood. So that 
both the blood to the gland and the saliva secreted tend to become 
cooled. And thus it would be possible for the recorded temperature of 
the saliva to be less than that of aortie blood, although the temperature 
of the saliva secreted were higher than that of the blood supplied to the 
gland. 


ELECTRICAL CHANGES IN THE SALIVARY GLANDS. 


The electrical currents of the salivary glands of the dog and cat 
have been made the subject of observation by Bayliss and Bradford,? and 
by Bradford. In such experiments, one non-polarisable electrode is 
placed upon the outer convex surface of the gland, and the other upon 
the gland close to the hilus. It is convenient to use Hermann’s nomen- 
clature for the currents which may be observed. When the outer 
surface of the gland is positive to the hilus, so that the direction of the 
current in the galvanometer cireuit is towards the hilus, and in the 


1 Journ. Physiol., Cambridge and London, 1894, vol. xvi. p. 351. 

2 It may be mentioned that the blood temperatures recorded by Bayliss and Hill are in 
nearly all cases less than those recorded by Ludwig, but no definite conclusion can be 
drawn from this. : 

3 Proc. Roy. Soc. London, 1886, No. 243, p. 203 ; Internat. Journ. Anat. and Histol., 
1887, vol. iv. The ingoing current of the skin of the frog was discovered by du Bois Rey- 
mond in 1857. He attributed it to the glands present in the skin (cf. ‘‘ Untersuch. i. 
thierische Elektricitit,” 1860. Bd. ii. 

+ Journ. Physiol., Cambridge and London, 1887, vol. viii. p. 86. 


518 THE SALIVARY GLANDS. 


gland itself from the gland-cells to the surrounding tissue—the current 
is an ingoing current. When the outer surface of the gland is negative 
to the hilus, so that the direction of the current in the galvanometer 
circuit is from the hilus to the outer surface, and in the gland itself 
from the gland-cells towards the duct, the current is outgoing. The 
outgoing current, then, is one in the direction of the fiow of the saliva 
secreted. 

The current of rest may be either outgoimg or ingoing. It is 
usually outgoing in the submaxillary gland of the dog, and usually ingoing 
in the submaxillary gland of the cat. The causes of the difference of 
direction have not been determined. 

Any stimulation of nerves which causes a rapid flow of saliva will 
cause a strong outgoing current. When the flow of saliva is sight, the 
current, as a rule, is either diphasic, first outgoing and then ingoing, or 
ingoing only. Thus in the submaxillary or parotid gland of the dog, 
stimulation of the cranial nerve causes an outgoing current, and stimula- 
tion of the sympathetic, provided the secretion be shght, causes an 
ingoing current. The ingoing current begins less quickly and is less 
strong than the outgoing current. 


In the submaxillary gland of the dog, the current of rest is said to vary 
from 1-500 to 1-10 of a volt. The outgoing current, caused by stimulating the 
chorda tympani, begins about 0°37 seconds after the beginning of the stimu- 
lation, and before saliva appears in the duct; it reaches its maximum before 
the maximum rate of secretion is attained. It may undergo temporary 
diminution or reversal, indicating the development of an ingoing current. 
The ingoing current, caused by stimulating the sympathetic, begins two to 
three seconds after the beginning of the stimulation, and only slowly attains 
its maximum. 

In the submaxillary gland of the cat, stimulation, either of the chorda or 
of the sympathetic, causes, in most cases, first an outgoing and then an ingoing 
current. 


Atropine annuls the effect of nerve stimulation, except perhaps in 
the case of the sympathetic of the dog; here the ingoing current pro- 
duced by stimulation is much reduced, but it is not clear that it is com- 
pletely abolished even by 100 mgrms. of atropine. Atropine annuls the 
outgoing current of stimulation before the ingoing. The amount of 
atropine required to abolish the outgoing current of stimulation is approxi- 
mately that required to render the flow of saliva very slight. The 
amount of atropine required to abolish the ingoing current of stimulation 
is approximately that required to paralyse completely the secretory 
activity of the nerve stimulated (cf. p. 512). 

Bradford attributes the ingoing current to “changes in the gland 
cells, leading to the elaboration of the organic constituents of the saliva,” 
these being caused by the action of Heidenhain’s trophic fibres, and 
thinks that the outgoing current is probably due “either to the passage 
of the fluid part of the secretion through the walls of the alveoli, or to 
the changes in the gland structures, that follow the excitation of a 
secretory nerve and precede the gland flow.” 


Most of the facts could be accounted for by supposing that the outgoing 
current is due to physical causes, namely, due to the passage of fluid through the 
gland-cells ; and that the ingoing current is due to chemical causes, namely, the 
metabolic changes in. the gland-cells, but the questions involved are too com- 


SECTION OF GLANDULAR NERVES. 519 


plex to allow a definite conclusion to be arrived at. In any adequate discussion 
of the matter, the facts regarding the production of electric currents in other 
parts of the body, and éspecially in the skin and mucous membrane, would 
have to be taken into account. One or two points only we can mention here. 
In the skin and mucous membranes of the frog and other animals investigated, 
there is generally an ingoing electric current, which is increased by weak 
stimulation. Hermann! considers both currents to be due to an “ apobiotic ” 
change in the protoplasm. By “apobiotic” is meant any change which 
diminishes the vital energy of a part of the protoplasm, compared with the 
rest ; such as is produced by stimulation, the act'of dying, the change of proto- 
plasm to mucin or to keratin, and so forth. Parts undergoing apobiotic 
change are negative to the rest of the protoplasm. Thus, in a mucous cell, 
the inner mucous portion of the cell becomes negative to the outer proto- 
plasmic part, and a current is then set up, which passes in the galvanometer 
from capsule to hilus, and in the gland from mucous to protoplasmic portion, 
7.¢. there is an ingoing current. As to the outgoing current, Hermann is 
inclined to consider it as a simple diminution (negative variation) of the 
normal ingoing or secretory current; whilst Biedermann advocates the view 
that the outgoing current is due to anabolic (assimilatory) processes in the 
gland-cells. 


SECTION OF GLANDULAR NERVES. THE PARALYTIC SECRETION. 


Claude Bernard? was the first to make observations upon the effect 
of section of glandular nerves. He found that section of the chorda 
tympani in the dog caused the submaxillary gland in two or three days 
to enter into a state of slow continuous secretion. The slow flow of 
saliva continued for five to six weeks, and then stopped. During this 
time the gland itself diminished more and more in size. 

Since the secretion is the result of the section of nerve-fibres, it has 
been called the “paralytic secretion.” Claude Bernard attributed the 
secretion to the complete removal of nervous impulses. Thus the flow 
of saliva did not begin for two or three days, because the terminations 
of the chorda tympani in the gland required two or three days to 
degenerate completely. It stopped in five to six weeks, because then, 
he thought, the chorda fibres had regenerated. 

The question was taken up a few years later by Heidenhain.? In 
order to exclude the possibility of the paralytic secretion being caused 
by irritation of the duct or gland, he cut the chorda tympani in the 
tympanic cavity. The secretion occurred in the same way as when the 
nerve was cut peripherally of the ganglion, then called the submaxillary 
ganglion (cf. above, p. 481). It began in twenty-four hours at least, 
i.e. considerably earlier than the time given by Bernard. It was watery, 
and contained very little mucin; it contained many leucocytes (amee- 
boide Korperchen), and was in consequence somewhat cloudy. The 
secretion was at first very slow, but gradually increased in rapidity, so 
that in about a week a large drop might be secreted every twenty 
minutes. After three weeks it diminished markedly. The gland itself, 
as its size diminished, became of a yellowish tint, and waxy appearance. 

The time taken by the peripheral ends of the cut chorda tympani 


1 Arch. f. d. ges. Physiol., Bonn, 1894, Bd. lviii. S. 246. References to much of the 
earlier work will be found in this paper. 

2 Journ. de Vanat. et physiol., etc., Paris, 1864, tome i. p. 507. 

® Stud. d. physiol. Inst. zw Breslau, Leipzig, 1868, Heft 4, p. 73. 


520 THE SALIVARY GLANDS. 


fibres to degenerate is not quite accurately known, Heidenhain states 
that in the dog, stimulation of the chorda causes a secretion three to four 
days after its section, and imphes that later than this the nerve has no 
effect. In an experiment on the cat, I? obtained a copious secretion by 
stimulating the cut end of the chorda three days after section; a secre- 
tion too copious, it seemed to me, to be attributed to the nerve-cells 
which sometimes occur in the region stimulated. But Bradford,’ three 
days after section of the chordo-lingual nerve near the pterygoid muscle, 
obtained no secretion from stimulation of the nerve up to the point 
where the chorda tympani leaves the lingual. In the dog he found no 
effect five days after section, but no experiment was made at an earlier 
date. It appears, then, that the time required for a loss of irritability 
of the cut chorda tympani in the cat and dog lies somewhere between 
three and five days. 

Notwithstanding the early loss of irritability of the chorda tympani 
after section, stimulation of its nerve-strands near the gland will in the 
cat still cause secretion. In this way I obtained a fairly rapid secretion 
thirteen days after section of the nerve, and a slight secretion in another 
experiment forty-two days after section of the nerve. And Bradford 
obtained secretion from the chorda tympani in the cat up to eleven days 
after section of the chordo-lingual. In his experiments he sometimes 
obtained a secretion by stimulating the chorda immediately after it had 
left the lingual nerve, but sometimes only when the electrodes were 
shifted farther towards the gland. In the dog, five or more days after 
section, he obtained no secretion by stimulating the chorda in any part 
of its course. 

Vulpian* noticed in the dog, that a fortnight after section of the 
chorda tympani, injection of extract of jaborandi into a vein gave rise to 
a secretion, though less than normal. Extirpation of the superior 
cervical ganglion at the time of section did not affect the result. In 
the cat, I found that thirteen days after section of the chorda, venous 
injection of a few megrms. of pilocarpine caused a copious secretion, 
and that forty-two days after section of the nerve, pilocarpine still caused 
a secretion, though distinctly less than on the opposite side. 

These experiments, taken together with those already given on the 
action of nicotine (cf. p. 515), and with our general knowledge of the 
relation of visceral nerve-fibres to nerve-cells, show that, on section of 
the chorda tympani, its nerve-fibres degenerate in three to five days up 
to the peripheral nerve-cells. The nerve-cells are placed chiefly in the 
gland itsel{—more so in the dog than in the cat. And there can be 
little doubt that the variations observed as the result of stimulating the 
peripheral portions of the chorda depend in the main upon variations in 
the position of the peripheral ganglia. In some animals, postganglonic 
fibres are stimulated when the electrodes are placed on the strands 
outside the gland; in other animals, this only occurs when the electrodes 
are placed in the hilus. As the gland diminishes in size it naturally 
gives a less copious secretion under the influence of pilocarpine. 


1 Heidenhain (Hermann’s ‘‘ Handbuch,” 1880, Bd. vi. S. 88) states that, although there 
was secretion, there was no increased flow of blood. 

* Journ. Physiol., Cambridge and London, 1885, vol. vi. p. 71 

° Ibid., 1888, vol. ix. p. 304. 

: Compt. rend. Acad. d. sc., Paris, 1878, tome Ixxxvii. p. 350. Before this, Prévost had 
stated that muscarine causes secretion after degeneration of the chorda tympani ; sof. ArekeS 
de physiol. norm. et path:, Paris, 1874, p. 719, “note. 


THE PARALYTIC SECRETION. 521 


The peripheral nerve-cells+ in connection with the gland may be 
spoken of as a local nerve-centre. This local centre is capable of 
exciting the gland-cells to activity long after the chorda tympani, which 
normally conveys impulses to it from the central nerve-centre, has 
degenerated. 

Heidenhain suggested that the paralytic secretion might be due to a 
stimulation of the gland-cells by the decomposition products of the 
stagnating saliva. He observed that if the duct were clamped for about 
a day, a slow secretion of w atery saliva ensued. The cases, however, are 
hardly comparable, inasmuch as, whilst the duct is closed, secretion is 
formed which partly distends the alveoli and partly is forced out of the 
ducts and lumina, and bathes all the tissues of the gland. 

A final explanation can hardly yet be given, but some observations 
made on’ the cat lead me to think that the secretion is the result of 
nervous stimuli. In the cat the paralytic secretion is much diminished 
and even stopped by excess of chloroform and by apnoea; and is 
increased markedly by dyspnoea; the dyspneeic flow takes place more 
readily than on the opposite side, and, so far as can be judged, more 
readily than in a normal gland. These results indicate that the 
paralytic secretion is due chiefly, at any rate, to a shght continuous 
excitation of the local nerve mechanism. 

Heidenhain found that the paralytic secretion also occurred in the dog, 
when the superior cervical ganglion was excised at the time of section of 
the chorda. In this case the secretion is due wholly to local changes. 
In the early stage of secretion in the cat, three days after section of the 
chorda alone, I noticed that section of the cervical sympathetic very 
much diminished or even stopped both the paralytic secretion and the 
dyspneic secretion, although, in the later stages, section of the cervical 
sympathetic had little or no effect. Probably, then, if the sympathetic 
is intact, the secretion which occurs in the first few days after section of 
the chorda is largely due to impulses travelling down the sympathetic 
from the central nervous system. 

The loss of weight which occurs in the submaxillary and the sub- 
lingual glands, after section of the chorda tympani, amounts in a few 
weeks to one-third to one-half of the original weight of the glands. 
Bradford has shown that section of Jacobson’s nerve causes a similar 
loss of weight in the parotid gland? of the cat. Whether complete 
atrophy takes place, and if so what time it requires, there is no evidence 
to show. 

In the submaxillary gland, and no doubt in the others also, the loss 
of weight is due to a loss of cell substance by the individual cells. And 
this loss is simply an instance of the gradual atrophy which occurs in 
tissues in the absence of functional activity. The persistent slight 
activity, of which the paralytic secretion is the sign, is quite insufficient 
to replace the normal exercise of function. 

In the dog, according to Heidenhain, the paralytic gland contains a 
number of alveoli, presenting the appearance of the alveoli of an active 
gland. In my experiments, both on the dog and cat, the gland-cells were 
undoubtedly in the resting state. In the cat the saliva obtained by 


1 Six weeks after section of the chorda in the cat, when the submaxillary gland had lost 
one-third to one-half of its weight, the nerve-cells in the alcohol-hardened gland presented 
no certain difference from the nerve-cells of the gland of the opposite side. 

* Bradford did not observe a paralytic secretion from the parotid. 


522 THE SALIVARY GLANDS. 


stimulating the postganglionic chorda fibres, and by injecting pilo- 
carpine, was distinctly viscid, and more viscid than normal. The alveoli 
mentioned by Heidenhain were, I am inclined to think, the demilunes 
which a decrease in the size of the mucous cells inevitably brings into 
prominence, notwithstanding an actual decrease in the size of the 
individual demilune cells. 

Stimulation of the cervical sympathetic, during the progress of the 
paralytic secretion, has practically its normal action both in the dog and 
the cat. In the dog, it gives, when stimulated after a sufficient interval 
of rest, a brief quick flow of watery saliva, corresponding with the 
augmented secretion, and after this a slow slight secretion even thicker 
than usual. If the stimulus be prolonged, there is a long pause in the 
paralytic secretion, due partly to anemia of the gland, and partly to the 
resistance offered to the flow by the thick saliva in the lumina and 
ducts. In the cat, the sympathetic produces secretion in the usual way 
and of the usual kind; and unless the stimulation be too prolonged, the 
paralytic secretion slowly creeps on in the intervals between the several 
stunulations. 

Heidenhain noticed in the dog that section of the chorda tympani on 
one side caused a slight continuous secretion from the submaxillary 
gland of the opposite side. The occurrence of such a secretion I con- 
firmed in the cat. It is convenient to have a name for this secretion, 
and I have called it the antiparalytic, or, more briefly, the antilytic 
secretion. In my experiments the antilytic secretion was stopped by 
apnoea and by excess of chloroform. ‘Dyspnoea caused a secretion 
apparently greater than normal, though less than on the paralytic side. 
No certain antilytic secretion was observed either thirteen or forty-two 
days after section of the chorda. In its early stage, three days after 
section of the opposite chorda, it was diminished by cutting the chorda 
of the same side, and abolished by cutting the sy mpathetic also. So far, 
then, as regards the cat, there is some eround for thinking that the anti- 
lytic secretion is transitor y and due to impulses set up in the central 
nervous system. 


Section of the chorda tympani probably leads to slow changes in the nerve- 
cells of the secretory centre which are connected with the chorda fibres ; 
these changes might make the central nerve-cells more irritable, so that they 
passed into a condition of continuous slight activity, thus producing the anti- 
lytic secretion. Or the antilytic secretion might, as suggested by Bradford, be 
simply a reflex from the tissues injured during the section of the chorda. 

According to Heidenhain, the antilytic secretion in the dog continues after 
section of both chorda tympani and sympathetic nerves. As it is difficult to 
see why the local mechanism should be so easily thrown out of gear, it is best 
to wait for further observations on the matter. 

Little is known as to the time taken for the chorda tympani fibres to 
regenerate. Ina puppy, I obtained, three months after section of the chorda 
tympani, a secretion much as usual, on stimulating either the nerve which had 
been cut or the chordo-lingual, so that presumably regeneration is fairly com- 
plete in three months. 


Section of the cervical sympathetic! has no observable permanent effect 
upon the gland, and it causes no paralytic secretion. The blood vessels 
for a time dilate, but this soon passes off. The nerve soon loses its 


1 Cf. Langley, op. cit., and Bradford, op. cit. 


REFLEX ACTION OF PERIPHERAL GANGLIA. 528 


irritability ; in the cat, according to Bradford, it gives no secretion three 
days after section. 

Stimulation of the ganglion will still cause secretion and pallor of 
the gland for several weeks after section of the nerve, and possibly 
indefinitely. 

Excision of the superior cervical ganglion has also no certain effect 
upon the salivary glands, and does not give rise to a secretion. In the 
rabbit I could see no decrease in the size of the submaxillary glands, 
or alteration in their histological appearance, nine, sixteen, and twenty- 
three days respectively after removal of the ganglion, nor in a case in 
which the ganglion had been removed five years previously by Dr. Pye- 
Smith. The chorda tympani still causes secretion and flushing of the 
gland, though the flushing is apparently less than normal. Bradford 
removed the superior cervical ganglion in the cat. He found no atrophy 
of the gland up to seven weeks after the operation: indeed, in his cases 
both the submaxillary and the parotid glands were somewhat heavier 
on the operated than on the sound side. Removal of the ganglion 
causes the sympathetic filaments on the gland artery to degenerate, the 
loss of irritability being fairly rapid; thus, three days after the operation, 
Bradford obtained no secretion on stimulating these nerve-filaments. 


SECRETION DUE TO A REFLEX ACTION OF PERIPHERAL GANGLIA. 


We may reject the view of Bernard! that a secretion can be 
- obtained from the submaxillary gland of the dog, by means of nervous 
impulses passing from the mucous membrane of the tongue by the 
lingual nerve to the “submaxillary” ganglion, and thence to the gland. 
The direct proof alleged in favour of this view was that occasionally, 
after section of the chordo-lingual, direct stimulation of the tongue, or 
the application of ether, caused a slight secretion. As no anesthetics 
were given, it is quite possible that a slight flow from the duct might be 
caused by reflex movements. The result was not obtained by Eckhard, 
Bidder, and others; and until it can be obtained with some constancy, 
and after administering at any rate a moderate amount of anesthetics, it 
may properly be disregarded. 

The indirect proof alleged is that after section of the chordo-lingual, 
stimulation of the lingual on its course to the tongue (the nerve being 
cut and the central end stimulated) causes a secretion from the sub- 
maxillary gland. This, in fact, is commonly the case. The amount of 
the secretion, broadly speaking, increases the nearer the electrodes are to 
the chorda tympani. It is often barely more than perceptible. The 
fact observed by Bernard, that three to five days after section of the 
chordo-lingual, a secretion could no longer be obtained, seems sufficient, 
with our present knowledge of the central nervous system, to show that 
the lingual secretion cannot be reflex in the ordinary sense. 

There can be little doubt that Schiff’s? explanation is in the main 
correct, namely, that some secretory fibres for the submaxillary gland, 
instead of running to it direct by the chorda tympani, accompany the 
lingual for a short distance and then run back to the gland. Schiff 


1 Journ. de Vanat. et physiol., etc., Paris, 1864, tome i. p. 507. For some further 
account of the earlier papers, see Foster’s ‘‘‘lext-book of Physiology,” 1879, 3rd edition, p. 
240. 

2 “«Lecons sur la physiol. de la digestion,” 1867, tome i. p. 284. 


524 THE SALIVARY GLANDS. 


seems to have thought that these recurrent fibres ran in a single bundle 
a considerable distance down the lingual, for he says that when the 
lingual nerve is cut about 2 cm. beyond the point where the chorda 
tympani leaves it, and time is allowed for degeneration, no secretion 1s 
obtained by stimulating the central end; a negative result. which was 
not obtained by Wertheimer. Wertheimer’s 8 positive result then may 
be taken as showing that the recurrent fibres leave the lingual at more 
than one spot. 

But it is nevertheless possible that on stimulating the central end of 
the lingual a secretion should be obtained which is not produced by 
recurrent fibres, and which is due to nervous impulses passing through 
local nerve-cells. The nerve-cells on the course of the chorda tympani 
are, as we have seen, scattered; if the chorda tympani fibres branch 
before running to these cells, stimulation of one of the branches would 
probably cause a nervous impulse to pass to the more central branches 
and to the cells connected with them. This would be a reflex through 
efferent fibres of the kind described in some other peripheral ganglia 
Such action with the actual anatomical arrangements is more likely to be 
obtained from the sublingual than from the submaxillary gland. It 
would, of course, be annulled by degeneration of the chorda ty mpani. 


Direct IRRITABILITY OF GLAND-CELLS. 


It is natural to suppose that stimulation of the gland-cells by 
electrical, chemical, or mechanical stimuli should be capable of causing a 
secretion. There is, however, no direct evidence that this is the case. 
After atropine has been given, no secretion has been obtaimed; but it 
must be mentioned that, even when the nerve-endings in the sub- 
maxillary gland are in a full state of irritability, it is difficult to obtain 
secretion from it by electrical or other stimuli apphed to its outer sur- 


face, and which do not affect the internal bundles of nerves.2 


EXTIRPATION OF SALIVARY GLANDS, INJECTION OF SALIVA INTO 
THE BLoop. 


The extirpation of all the salivary glands is, of course, impossible ; 
but the large salivary glands, ze. those which secrete by far the greater 
portion of the saliva, can be cut out. This has been done by Fehr.4 
He states that in the dog he removed not only the parotid, submaxillary, 
and sublingual glands on both sides, but also the orbital glands. The 
operation had no appreciable effect on nutrition; and the only difference 
in the behaviour of the animal was that it drank more water. A 
similar result was observed by Schafer and Moore. They removed 
from a dog the parotid, the submaxillary, and the larger part of the sub- 
lingual olands. There was no disturbance of nitrogenous metabolism , 
and neither sugar nor albumin appeared in the urine. Carbohydrates 


1 Arch. de physiol. norm. et path., Paris, 1890, p. 519. 

* Langley and Anderson, Jowrn. Physiol., Cambridge and London, 1894, vol. xvi. 
p. 410. 

> Bernard (‘‘Lecons sur la propriétés physiologiques,” etc., 1859, tome ii.) found, by 
stimulating the gland directly, that pain was caused. 

4 Henle and Meissner's Jehr esb., in Ztschr. f. rat. Med., 1862, p. 255. 

fe ‘* Proc. Physiol. Soc.,” 1896 p- xui., Journ. Physiol., Cambridge and London, 
WOlle exec 


GENERAL CONSIDERATIONS. 525 


were well digested, and the animal throve on a diet of bread and 
milk. 

The salivary glands, then, in the domestic dog, appear to be rather 
a convenience than a necessity, and there is no evidence that they have 
any “internal secretion”; carbonic acid passes from the gland-cells to 
the blood, but there is no indication that any other substance does so. 

Saliva injected into the blood is much less harmful than might be 
expected. Bernard,! indeed, injected considerable quantities into a vein 
of a dog to which no anesthetics had been given, and did not observe a 
result of any kind. Extracts of the salivary glands injected into the 
blood cause a temporary fall of blood pressure,? but so many substances 
in solution do this that the action cannot be regarded as specific. 


GENERAL CONSIDERATIONS ; THEORIES AS TO THE MODE OF ACTION 
OF SECRETORY NERVES.® 


The facts which show that secretory nerve-fibres exist in the cranial 

nerves are so well known, that it is not necessary to consider them in 
detail. It is sufficient here to recall the fundamental facts, that secre- 
tion may in each salivary gland take place at a pressure higher than 
that of the blood supplied to the gland, and that nerve-fibres end in 
connection with the gland-cells.* 
_ In the case of the sympathetic, the comparatively sheght amount 
and the transitory nature of the secretion, render the question less clear. 
It was in fact suggested,’ early in the history of sympathetic saliva, 
that the cervical sympathetic nerve causes a secretion solely in con- 
sequence of the pressure exercised on the gland-cells by the contraction 
of the blood vessels, brought about by stimulation of the nerve. Such a 
view offers a plausible explanation of many of the facts relating to the 
secretory action of the sympathetic, such as the normal small quantity 
of the secretion in the dog, the increased quantity after the cranial nerve 
has been stimulated, the rapidity with which the maximum rate of the 
“augmented” saliva is attained, the normal absence of reflex secretion 
by way of the sympathetic when sapid substances are placed on the 
tongue, and the absence of effect of atropine and pilocarpine upon the 
secretory function of the sympathetic. 

But a closer inquiry shows, nevertheless, that this view is untenable 
On the general theory it may be noted, that the constriction of the small 
arteries of the gland in all probability decreases the pressure on the 
gland-cells instead of increasing it. On the experimental side, we may 
mention three points. 

1. The constriction of the blood vessels has at times no relation to 


1“ Tecons de physiol. expér.,” 1856, p. 141. 

? Schafer and Oliver, Journ. Physiol., Cambridge and London, 1895, vol. xviii. p. 277. 

3 For a general historical account of the views which have been held with regard to 
secretion, I may refer the reader to Prof. Gamgee’s Address to the Biological Section of the 
British Association in 1882, and to Prof. Heidenhain’s Introductory Account in Hermann’s 
‘* Handbuch,” 1880, Bd. v. Th. 1, 8S. 1-13. 

4 Cf. Fusari et Panasci, Arch. ital. de biol., Turin, 1891, tome xiv.; G. Retzius, 
Biol. Untersuch., Stockholm, 1892, N. F., Bde. iii., iv.; Korolkow, Anat. Anz., 
Jena, 1892, Bd. vii. S. 580; A. Dogiel, Arch. f. mikr., Anat. Bonn, 1893, Bd. xlii. ; 
Berkeley, Johns Hopkins Hosp. Rep., Baltimore, 1894, vol. v.; C. Arnstein, Anat. Anz., 
_ Jena, 1895, Bd. x. S. 410; G. C. Huber, Journ. Exper. Med., Baltimore, 1896, vol. i. 

. 281. 

; 5 Griinhagen, Ztschr. f. rat. Med., 1868, Bd. xxxiii. S. 258. 


526 THE SALIVARY GLANDS. 


the tlow of saliva. Thus, on stimulating the cervical sympathetic in the 
dog, it may happen that the secretion does not begin until the pallor of the 
gland and the reduction of blood flow are about maximal; the slow flow 
of saliva may then continue without change in the blood flow, and may 
even continue after the end of the stimulation, when the blood vessels 
are dilated. In the cat, contraction of blood vessels without any flow 
of saliva can be easily observed by stimulating the sympathetic after 
about 30 mgrms. of atropine have been injected into the blood. 

2. The quantity of saliva obtained by squeezing the gland is less 
than that obtained by stimulating the sympathetic. This is most 
readily observed in the submaxillary gland of the cat, in which about 
ten times as much saliva is usually obtained by stimulating the sympa- 
thetic as by squeezing the gland. 

3. The total amount of saliva obtained by stimulating the sympathetic 
is, in some cases, too great for it to be obtained by simple expression of 
fluid from the gland. This is perhaps most striking in the case of the 
augmented secretion of the submaxillary gland of the dog. In favour- 
able circumstances, } to } ¢.c. of saliva may be obtained by a single 
continuous stimulation, and with a diminution in the size of the gland 
not appreciably greater than would be accounted for by the dimimution 
in the amount of blood in it. 

Some of these observations, it will be observed, negative also the 
possibility that the sympathetic saliva can be due to pressure exercised 
by contractile tissue other than blood vessels around the alveoli. 

We conclude, then, that both the cranial and the sympathetic nerves 
contain fibres which end in connection with the gland-cells, and which 
are capable of causing changes in the cells leadig to secretion; and 
we pass on to consider whether the secretory nerve-fibres are of more 
than one kind. There are two possibilities to take into account :—first, 
whether there are fibres inhibiting the secretion as well as fibres excit- 
ing the secretion ; and, secondly, whether there are fibres causing 
chemical changes in the gland distinct from those which cause the flow 
of fluid. 

The former possibility we may treat briefly. Until it is shown that 
the decrease in the blood flow through the gland which the sympathetic 
causes is insufficient to account for the decrease in the flow of saliva 
which the sympathetic at times produces, this hypothesis of inhibitory 
fibres does not need serious attention. 

The second possibility we must consider more at length. The 
theory of the existence of two kinds of nerve-fibres in secretory nerves 
is due to Heidenhain.* 

According to this theory, the secretory fibres proper cause certain 
unknown changes in the cells leading to the passage of fluid through 
them. The trophic fibres cause chemical changes in the cells leading, 
on the one hand, to the growth of protoplasm, and, on the other, to the 
conversion of the stored-up secretory material into a more soluble form. 
Further, according to this theory, the proportion of these two kinds of 
nerve-fibres is different in cranial and sympathetic nerves. The cranial 
nerve contains more secretory than trophic fibres. The sympathetic 
nerve contains more trophic than secretory fibres. 

The trophic fibres, it will be observed, have two functions, not 
necessarily connected with one another. The evidence that they cause 

1 Heidenhain, Hermann’s ‘‘ Handbuch,” 1880, Bd. v. (1) p. 78. 


GENERAL CONSIDERATIONS. 527 


a erowth of protoplasm is derived from the microscopic: al examination 
of the various glands, after stimulating the sympathetic. Thus, 
according to Heidenhain—to take the most s striking example adduced 
by him—if the cervical sympathetic be stimulated in the dog for several 
hours, there is no secretion from the parotid gland, but the gland-cells 
show a great increase in carmine-staining material, i.e. a considerable 
growth of protoplasm. 

I have not been able to convince myself that any considerable 
changes of this nature take place. On stimulating the sympathetic the 
thick secretion usually stops up the ducts, and if any further secretion 
takes place it can only pass out into the lymph spaces. After 
stimulating the sympathetic for five to seven hours, I do not find any 
marked increase in the staining power of the cells ; and the fresh gland 
either shows no outer non-granular zone at all, or a very small one. 

The evidence that a separate class of trophic nerve-fibres exists, 
which converts stored-up material into a more soluble form, rests on 
certain facts, which we will discuss as far as possible separately. In the 
first place, there are the facts adduced to prove that soluble substance is 
formed during secretion, and which do not touch the question whether 
the formation is due to a special nerve-fibre or not. 

. 1. It was shown by Heidenhain that the percentage of organic 
substance in saliva, secreted under the influence of the cranial nerve, 
increases with the rate of secretion. On this fact Heidenhain argued 
somewhat as follows: If the solvent power of the fluid passing through 
the cells remains constant, and the solubility of the stored-up substance 
in the cell also remains constant, the amount of the stored-up substance 
dissolved by the fluid in its passage through the cell will decrease as the 
rate of its passage increases. For, below saturation point, the amount 
dissolved must decrease the less the time the solvent is in contact with 
the solvend. But, in fact, the slower the passage of the solvent the less 
it dissolves; hence, with increasing rate of flow, there must be either an 
increase in the solvent power of the fluid, or an increase in the solubility 
of the stored-up substance. Heidenhain considered that in mucous 
saliva, at any rate, the only substance which could increase the solvent 
power of the fluid was sodium carbonate. And this salt, he found, did 
not increase, as saliva was secreted more rapidly. In consequence, 
he concluded that the substance in the cell must become more soluble. 
An increase in solubility of part of the stored-up substance was then a 
result of stimulating nerve-fibres. 

But it is by no means clear that the rapidly-secreted fluid is not a 
better solvent than the fluid secreted slowly. Werther, working in 
Heidenhain’s laboratory, found in fact that the percentage of sodium 
earbonate in the submaxillary saliva of the dog does increase, though 
but slightly, with the rate of secretion of saliva. And, in addition, “it 
cannot be ‘regarded as certain that sodium chloride and other neutral 
salts do not aid in the solution of the substances stored up in the cells. 
The evidence, indeed, seems to me to be on the other side. And, as we 
have seen, when saliva is secreted more rapidly, there is an increase in 
the percentage of salts as well as in that of organic substances. Finally, 
the statement that the faster the fluid passes through the cell, the less 
substance it will dissolve, depends on the assumption that in slowly- 
secreted and in rapidly-secreted saliva, the fluid has an equal oppor- 
tunity of dissolving the stored-up material. This is not necessarily the 


528 THE SALIVARY GLANDS. 

ease; the more rapidly-flowing fluid might pass more freely into the 
intracellular spaces, and come into more intimate contact with the 
mucous or other stored-up material of the cell. 

2. Better evidence of the formation of soluble substances in gland- 
cells, under the action of nerve stimulation, is afforded by the after-action 
of strong nerve stimulation. If, between two weak stimulations of a 
cranial nerve, a strong stimulation of the same nerve or a stimulation 
of the sympathetic nerve be introduced, the second weak nerve 
stimulation gives rise to saliva containing a higher percentage of organic 
substance than that produced by the first similar stimulation. The 
fact may be taken as showing that the strong stimulation, introduced 
between the two weak ones, has converted slightly soluble into more 
soluble material, which has only partially been carried out of the cell. 
But this is not the only possible explanation. We can imagine that the 
stronger the stimulus the more the fluid passing through the cell will 
be brought into contact with the stored-up substance, with the result 
that more of this substance will absorb water and pass a stage on the 
way to solution than would otherwise be the case. And consequently, 
for some time after a strong stimulus, any fluid passing through the 
cell would find substance already on the way to solution or alre eady 
dissolved, without any alteration in its chemical composition. 

The experimental evidence, then, of the formation of a soluble 
substance during secretion is not satisfactory. And, in fact, it is 
doubtful whether the glands contain any stored-up organic substance 
in a “comparatively insoluble” state. The granules of “the glands are 
seen to enter readily into solution—micellar or other—when | a crushed 
piece of the gland is irrigated with dilute alkaline salt solution. The 
mucin or mucins of saliva have not been shown to be different from the 
mucin or mucins contained in the salivary glands. The mucous material 
of the glands is often spoken of as mucigen, following the analogy of 
trypsinogen and pepsinogen; but it is well to remember that there is 
nothing to show that trypsinogen and pepsinogen are less soluble in 
dilute saline solution than trypsin and pepsin; and further, that there is 
some evidence that the cesophageal glands of the frog secrete pepsinogen 
as such, and not as pepsin. 

Supposing, however, it were shown that nerve stimulation causes an 
increase in solubility of secretory material, it would still remain to show 
that this change is caused by a special class of nerve-fibres; and to this 
part of the theory we may now pass. 

It was thought that direct proof of the separate existence of trophic 
fibres was afforded by the results on the parotid gland of stimulating 
the sympathetic in the dog. Stimulation of the sympathetic caused no 
flow of saliva, but caused nevertheless histological changes in the 
gland-cells, and a great increase in the percentage composition of the 
saliva obtained in other ways. Here was apparently an instance of 
nerve-fibres producing the changes demanded of the trophic fibres, by 
hypothesis, and producing no others. 

But we have seen (p. 498) that the sympathetic is capable, in 
favourable circumstances, of causing a flow of saliva from the parotid 
gland of the dog. Since, then, secretory fibres are present in the 
sympathetic strand supplying the parotid, the action of the nerve in 
this particular instance cannot, without further examination, be taken to 
show the existence of an additional class of nerve-fibres. 


GENERAL CONSIDERATIONS. 529 


We come, then, to a comparison of the relative effects of the cranial and 
sympathetic nerves as the final part of the evidence for the existence of 
two classes of nerve-fibres. It is said that the difference in the percentage 
composition of sympathetic saliva, and of that produced by stimulating 
, the cranial nerve, can only be satisfactorily explained by supposing that 
secretory and trophic fibres are present in both, and that the number 
of trophic fibres relatively to the secretory is greater in the sympathetic 
than in the cranial nerves. 

This conclusion seems to me to be legitimate and unavoidable, if a 
diminution in. the blood supply to the glands brought about by vaso- 
constrictor nerves does not markedly increase the percentage of organic 
substance in tlie saliva secreted. But this, so far, has not been shown 
to be the case (cf. p. 508). The question can hardly be settled until 
means are found of stimulating the sympathetic vaso-constrictor fibres 
of the salivary glands without stimulating the sympathetic secretory 
fibres. 

We find, then, that the hypothesis of a separate class of trophic 
fibres, although affording a convenient explanation of a certain number 
of facts, can hardly be considered proved at any point. It presents also 
eertain difficulties of its own which we need not insist on here. 

On the whole, I think the most probable view is, that only one 
kind of nerve-fibre runs to the gland-cells, and that this causes all the 
changes in the gland-cells which are capable of being caused by nerve 
stimulation. These changes include the taking up proteid material 
from the lymph, some katabolic action—shown ‘by the setting free of 
carbonic acid—and changes leading to the passage of water and salts 
through the cell. It is not improbable that the nervous impulses hasten 
the conversion of absorbed proteid to secretory substances, and it is 
perhaps possible that they increase the solubility of the secretory sub- 
stance already formed. The effect of the secretory fibres, as regards 
the amount and percentage composition of the saliva obtained, would 
naturally vary with the strength of the stimulus, the condition of the 
gland at the time, the quality and quantity of the blood flowing through 
the gland. 

The exact processes which take place in gland-cells and which lead 
to secretion is at present outside the range of our knowledge. The high 
secretory pressure naturally suggests osmosis as the cause of the passage 
of water and of salts. And, about five and twenty years ago, the view 
that secretion is due to the formation in the cells of a substance of high 
endosmotic pressure was put forward by Hering and others. Much 
more is known now of the phenomena of osmosis than was known then ; 
but the nature of the process is still so obscure, that to attempt to 
explain secretion on the lines of osmosis is to venture on little better 
than conjecture. 


It may, however, be worth while to state briefly some points regarding the 
relation, or possible relation, of osmosis to secretion. 

We will consider, first, what facts of secretion we could in some sort 
account for, on the theory that osmotic pressure is of the same nature as 
gaseous pressure, and assuming that osmosis does take place in the gland-cells. 

The facts which it seems most feasible to offer an explanation of are, the 
occurrence of secretion when the cells are stimulated and not at other times, 
the increase in the rate of flow during stimulation, the increase in the per- 
centage of salts in saliva with increase in the rate of flow. 

VOL. 1.—34 


53° THE SALIVARY GLANDS. 


We may speak of the alveolar cells as forming a membrane, and call the 
part towards the lymph the outer layer of it, and the part towards the lumina 
of the gland the inner layer. In the inner layer are spaces containing soluble 
organic substance. 

The explanation of the above-mentioned facts on the osmotic theory might 
be as follows :—The membrane is impermeable in the unstimulated state; on © 
stimulation, a rearrangement of its molecules takes place, so that, of immedi- 
ately adjoining portions, parts are permeable to water and parts are permeable 
to salts also, whilst parts remain impermeable. On increasing the strength of 
the stimulation, a larger and larger area of the membrane becomes permeable, 
and of this a proportionately larger and larger part becomes permeable to 
salts. 

The increase in the percentage of organic substance in saliva, which accom- 
panies increased rate of flow, might be due simply to the greater percentage 
of salts causing an increase in the solvent power of the fluid, or to a larger 
proportion of the fluid passing into the spaces of the inner layer. 

Proteid molecules do not pass through the gland-cells, but they enter it, 
and are deposited, forming the outer non-granular zone; the process is spoken 
of as the growth of protoplasm. We have reason to believe that the rate of 
growth of the protoplasm increases more than the rate of flow of fluid as the 
stimuli pass from weak to strong. 

To account for this on the osmotic theory, it must be supposed that only 
the outermost portion of the membrane becomes permeable to proteids, so that 
the proteid molecules are blocked in their passage, and further that the ratio 
of permeability to proteids and to water is greater with strong than with weak 
stimuli. The theory becomes further complicated, if we have to apply it also 
to a taking up of proteid during rest (cf. p. 486), when there is no passage of 
fluid; for in this case the inner part of the membrane at least must be im- 
permeable to water, whilst the outer part is permeable to proteids. 

So far we have assumed that the conditions of the solutions on the two 
sides of the membrane are such as would lead to an osmotic flow through it, 
directed from its outer to its inner surface. But this is precisely the point it 
is difficult to be clear about. There is no obvious reason why the fluid in 
contact with surfaces of the membrane bounding the spaces should be very 
different from the fluid issuing from the inner surface of the membrane. But 
the saliva contains commonly less organic substance and less salts than the 
lymph. Why then should fluid pass from the lymph to the saliva? It can 
only be said that it is perhaps possible that a passage both of water and salts 
might take place if the organic substance in the spaces formed some combina- 
tion with water and salts, of which at present we have not sufficient evidence. 

The hypothesis which I have stated above seems capable of being put 
to the test of experiment, and of being either proved or disproved. Failing 
it, we are, I think, driven to suppose—apart from the hypothesis of special 
vital activity—that the outer layer of the cell forms a loose chemical combina- 
tion with various substances of the lymph, and that these are passed on from 
molecule to molecule and disassociated at the inner surface. A process of this 
kind forms the basis of the chemical theory of osmosis. And it seems to me 
not improbable that such a process occurs in gland-cells, but it is extremely 
difficult to see how to bring any experimental evidence to bear directly on the 
question. The investigation appears to demand, as a preliminary, an intimate 
knowledge of the chemical nature of the membrane. The membrane consists 
of protoplasm. And there are few problems in physiology which appear more 
remote from solution than that of the chemical nature of living substance. 


MECHANISM OF SECRETION OF GASTRIC, 
PANCREATIC, AND INTESTINAL JUICES. 


By J. 5S. EpKus. 


ConTENtTS.—Histological Appearances of the Secretory Conditions of the Stomach, 
p- 531—Functions of the Cells and Regions of the Stomach, p. 532—Methods 
of obtaining Gastric Juice, p. 536—Influence of the Nervous System on Gastric 
Secretion, p. 537—Conditions which provoke Secretion, p. 540—Formation of 
the Ferments of Gastric Juice, p. 542—Formation of Rennin, p. 543—Variations 
in Gastric Juice during Digestion, p. 544—Histological Appearances of the 
Secretory Conditions of the Pancreas, p. 546—Influence of the Nervous System 
upon Pancreatic Secretion, p. 547—Conditions which provoke the Flow of 
Pancreatic Juice, p. 551—Ferments of the Pancreatic Juice and their Ante- 
cedents, p. 551—Variations in Pancreatic Juice during Digestion, p. 553— 
Evidence of Secretion in the Intestine, p. 554. 


THE MECHANISM OF GASTRIC SECRETION. 


The histological appearances of the different secretory con- 
ditions of the stomach, and the relation of the secretory granules 
to the enzyme.—Though the existence of specific granules in secretory 
glands had previously been pointed out in connection with the pancreas 
vand some salivary glands, it was not till 1879 that their existence was 
also observed in the secreting cells of the gastric mucous membrane by 
Langley and Sewall,) who showed that the chief or central cells are, in 
the resting condition, crowded with conspicuous granules, and that 
during digestion the granules in these cells diminish. As far as the 
ovoid or border cells are concerned, granules are to be seen in these, but 
they are much smaller in size, though quite discrete. 

After digestion the cells take on different appearances, which consist 
mainly in the decrease of the number of granules. This decrease may 
be manifested in two different ways. In the first case, and the more 
typical, the outer border of the cell alone may show the lack of granules, 
the luminal border retaining them, unless in an extreme condition of 
exhaustion. In the second case, there may be a uniform decrease of 
granules throughout the cell, accompanied by a diminution in size 
of the cell, but unaccompanied by any formation of zones. These two 
forms of decrease may occur in different parts of the gastric mucous 
membrane of the same animal. Thus in the greater curvature of the 
stomach in both the rabbit and guinea-pig there is a formation of zones, 
in the cells of the fundus such a division is not seen. 


1 “Changes in Pepsin-forming Glands,” Jowrn. Physiol., Cambridge and London, 1879, 
vol. ii. 


532 MECHANISM OF SECRETION OF GASTRIC JUICE. 


At the pyloric end of the dog’s stomach in the resting or exhausted 
state, an appearance is seen which consists of small and obscure granules 
somewhat radially arranged, an appearance which bears a slight resem- 
blance to that seen in the ducts of salivary glands in the fresh condition. 
A very marked difference exists, however, between the pyloric cells and 
the cardiac cells, and there seems little doubt that considerable histo- 
logical distinction obtains. Nevertheless, attempts have been made by 
Ebstein + and others to prove the identity of the chief cells of the cardiac 
end with the lining cells of the body of the pyloric glands. It may be 
stated that Langley and Sewall found no difference in the pyloric cells 
whether the glands were in a resting or active condition, and other later 
observations also show a marked uniformity of appearance in the cells 
whatever the secretory condition be. 

It may then be regarded as established that a diminution in the 
amount of granules characterises the chief cells as digestion advances. 
It has, moreover, been shown by Griitzner? and others, that as digestion 
advances the fundus glands contain less ferment than in hunger. It is 
therefore justifiable to conclude that the granules are in some way 
connected with the ferment. In addition to this, we have the fact that 
more pepsin can be obtained from the cells of the fundus in the rabbit 
than from the greater curvature, and it is in the fundus that the cells 
are conspicuously granular. We have, however, to consider that, though 
the chief cells will yield pepsin, yet they do not actually contain pepsin. 
If the granules then are connected with pepsin, it must be in some 
antecedent form. The probable explanation of this is that the granules 
of the chief cells consist wholly or in part of pepsinogen, the precursor 
of pepsin. 

The functions of the different forms of cells and of the different 
regions of the stomach.—Heidenhain originated the view that the 
chief cells were connected with the formation of pepsin, and the border 
cells with the formation of the acid of the gastric juice. The arguments 
upon which these conclusions are based are not direct, but though really 
inferential they appear to be supported by such evidence that but little 
doubt can be placed upon their accuracy. 

The reasons for regarding the chief cells as connected with the 
formation of pepsin have been dwelt upon in the previous section. But 
is there evidence to disconnect the border cells from this same function ? 
The most direct evidence we have is that, in the rabbit, the greater 
curvature contains more border cells than any other portion of the 
stomach ; the pyloric glands of the smaller curvature contain at most an 
occasional border cell here and there, yet the amount of pepsin produced 
by the two gland forms is scarcely different. The obvious conclusion is 
that the border cells do not form the ferment. On the other hand, it is 
noticed that the pyloric secretion is distinctly alkaline if separated from 
the rest of the stomach ; this is affirmed by Klemensiewicz,? Heidenhain,* 
and, later, Ackermann.? Apparently, therefore, such cells as are present 


i Arch. f. mikr. Anat., Bonn, 1870, Bd. vi. 

- ‘*Untersuch. ueber d. Bildung u. Aussch. des Pepsins,’’ Breslau, 1875. 
a pes den Suceus pyloricus,” Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1875, 

. Ixxi, 

* “Ueber die Pepsinbildung in den Pylorusdriisen,” Arch. f. d. ges. Physiol., Bonn, 
1878, Bd. xviii. 

° “ Experimentelle Beitriige zur Kenntniss des Pylorussecretes beim Hunde,” Skandin. 
Arch. f. Physiol., Leipzig, 1894, Bd. v. 


FUNCTIONS OF DIFFERENT FORMS OF CELLS. 533 


in the pyloric region do not contribute to the formation of acid. 
In the frog the source of the ferment is an alkaline juice fur- 
nished by the cesophageal glands, whilst the cells in the stomach bear 
resemblance to the border cells of the mammal, and here alone the 
acid of the juice is secreted. The deeper parts of the cardiac glands, 
where there are fewer border cells, do not give an acid reaction, the 
acid reaction being evident only at the mouths and upper parts of the 
glands. 

Claude Bernard! attempted to mark out the place where the free 
hydrochloric acid first appeared, by injecting intravenously a solution of 
ferric lactate followed by a solution of potassium ferrocyanide (these two 
compounds react with the production of Prussian blue only in the 
presence of a mineral acid). After the lapse of three quarters of an 
hour the animal was killed and the tissues examined. A blue pre- 
cipitate was only observed on the surface of the mucous membrane 
of the stomach, especially in the neighbourhood of the lesser cur- 
vature, but no trace of blue in the elands. This experiment might, 
at. first sight, be taken as indicating that the hydrochloric acid is first 
set free on the stomach itself, and is not formed in the cells of the 
gastric glands. Such a conclusion would be unwarranted. What the 
experiment does teach is that there is no accumulation of acid in the 
cells, but that the acid as rapidly as it is formed is thrown out of the 
cells as a secretion. 

Briicke? tried to solve the same problem by exposing the stomach of 
an animal in which digestion was actively going on, and carefully 
removing all but the mucous coat; both in the pigeon and in the rabbit 
the reaction of the exposed mucous layer to litmus paper was found to 
be faintly alkaline or very faintly acid, practically neutral, but on 
testing the inner surface of the mucous membrane it was, as usual, 
intensely acid. This again is an experiment which, had it given a 
positive result, would have shown conclusively that the acid was 
secreted by the gland-cells: but, giving as it did.a doubtful or negative 
result, it teaches little, and by no means proves the statement that 
the acid is not formed in the glands but in the stomach. In cutting 
into the stomach wall in this. manner, sources of alkali are tapped 
in the small blood vessels and lymph spaces which are capable of 
supplying more than sufficient alkali to neutralise any acid in the 
gland lumina. 

Briicke himself was not satisfied with this experiment, and attacked 
the problem by another method, which gave him results from which he 
concluded that the acid is really formed in the glands, and not in the 
stomach cavity. In birds, the gastric glands are compound glands 
forming flask-shaped bodies large enough to be easily seen without 
magnification. These compound olands possess also a flask-shaped 
cavity communicating with the stomach cavity by a comparatively 
narrow duct. Into this central cavity of the gland the secretion passes. 
Briicke took the secreting stomach of a fowl which had been killed 
during digestion, washed it out with magnesia suspended in water to 
neutralise the free acid on the surface of the mucous membrane, and 
sought out one of the above-described glands filled with secretion. 


1 **Tecons sur les propriétés physiol.,” Paris, 1859, vol. ii. 
* Sitzungsb. d. k. Akad. d, Wissensch., Wien, 1859, Bd. xxxvii.; ‘‘ Vorlesnngen,” 
Aufl. 4, Bd. i. S. 306. 


534 MECHANISM OF SECRETION OF GASTRIC JUICE. 


This he cut across, and tested the reaction of the fluid in its cavity. He 
found it as strongly acid as the secretion inside the stomach cavity. 
This experiment may be taken to show that the acid is secreted in the 
glands, but is continually being carried away by the stream of secretion. 
It might be objected against this experiment, that the fluid in the cavity 
of the compound gland is in communication with the stomach cavity 
and is acid by reason of admixture, but the communicating duct is too 
small to make this probable; moreover, there must be a continual 
stream flowing during secretion in the opposite direction from gland 
cavity to stomach cavity. That the gland cavity is not passively filled 
with secretion from the general stomach cavity, is also shown by the 
fact that some of these glands are swollen out with secretion while 
others are empty. It may be taken, then, that the gastric juice is acid 
as secreted by the gland- cells, and does not first become acid in the 
stomach. 

Such observations as have been made in order to ascertain whether 
the border cells yield an acid reaction have not been successful. 
Though the mass of evidence is very greatly in favour of the view that 
the border cells are the origin of ‘the acid of the juice, there are not 
wanting those who deny it entirely. Contejean! observed, as had 
previously been shown by Langley? that the stomach cells of the frog, 
although they secrete acid, also secrete pepsin. But a more remarkable 
statement is that the pylorus cells secrete an acid juice. This is so 
much at variance with the results of the majority of investigations, that 
it cannot be accepted as correct. If it were true, a conclusive proof 
would be furnished against the view that the border cells originate the 
acid. 

As regards the functions,of the different regions of the stomach, it 
may be stated that the fundus and the greater curvature form in most 
animals pepsin, hydrochloric acid, and other constituents of the gastric 
juice. But considerable discussion has taken place as to the functional 
importance of the pyloric region. That an extract can be made from 
the pyloric region containing pepsin is generally agreed, but such an 
extract, in comparison with one prepared from the rest of the stomach, 
has very small digestive value. Langley,2 in one experiment on the 
mucous membrane of the mole, found that if the digestive power of 
the pyloric region be taken as 1, that of the fundus would be 73. 
What then is the source of the pepsin that can be obtained from 
the pyloric mucous membrane? Is it pepsin formed by the gland 
cells in the pyloric region, or is it absorbed pepsin that has 
passed with the absorbed food into the mucous membrane of this 
region ? 

Wassmann * and y. Wittich+ have held that the pepsin was merely 
infiltrated pepsin, and Wassmann stated that it was removable by 
repeated washing with water. On the other hand, Ebstem and 
Griitzner® found that washing the mucous membrane of the pylorus 
causes but a very slow loss of pepsin. If, then, the cells of the mucous 


1 “Contribution a étude de la physiologie de l’estomac,” Centralbl. f. Physiol., 
Leipzig u. Wien, 1892. 

* Proc. Roy. Soc. London, 1881, No. 212. 

3 “* De digestione nonnulla,’’ Berolini, 1839. 

4“<Ueber die Pepsinwirkung der Pylorusdriisen,” Arch. f. d. ges. Physiol., Bonn, 1873, 
Bd. vii. 

°<*Ueber den Ort der Pepsinbildung in Magen,” ibid., 1872, Bd. vi. 


FUNCTIONS OF DIFFERENT FORMS OF CELLS. 535 


membrane absorb and fix pepsin, they fix it in a somewhat stable 
combination. Such absorption would be comparable to that which, as 
v. Wittich pointed out, fibrin exerts when placed in a glycerin solution 
of pepsin, the fibrin rapidly absorbing the pepsin so as finally to render 
the glycerin solution inert. The pepsin so absorbed can only be 
recovered by treatment with hydrochloric acid and not by extraction 
with water. Finally, Klemensiewicz! and, later, Heidenhain? have 
isolated portions of the pyloric mucous membrane, and observed the 
secretion thereby obtained. But in Klemensiewicz’s experiments the 
secretion was so mixed with abnormal fluids, such as pus, that the 
observations cannot be regarded as an index of the normal state of its 
composition. In Heidenhain’s observations this difficulty was avoided 
by the adoption of antiseptic precautions. He obtained a secretion 
alkaline in reaction, viscous in character, rich in pepsin and rennet 
ferment. With hydrochloric acid 0-1 per cent. it digested fibrin very 
energetically, and caused milk to clot in about a quarter of an hour. 
Both Klemensiewicz and Heidenhain insist on the strong proteolytic 
powers of the secretion; the former even states that it digests fibrin as 
rapidly as the juice from the mucous membrane of the fundus. There 
is then a oe amount of disparity between the results of extracting 
the mucous membrane with various fluids, and testing the proteoly tic 
powers of the extracts and those obtained by observing the peptic 
strength of the juice secreted by an isolated portion of the pyloric 
region of the stomach. We must therefore ask which furnishes us with 
the best criterion of the normal activity of the pyloric mucous 
membrane? By extracting with hy drochloric acid a large proportion of 
the pepsin present in the mucous membrane can ultimately be removed. 
But Klug? finds that, in order to obtain-all the pepsin from the pyloric 
mucous ‘membrane, it is necessary to make at least three successive 
extracts with hy drochlorie acid, each one of the duration of twenty-four 
hours. The first extract shows little or no peptic activity; the second and 
third, marked activity. He ascribes the change of activity to the pro- 
bability that the large amount of proteid present prevents the acid from 
separating the pepsin from its proteid compounds. But this difference 
is not found with the fundus, and it is somewhat difficult to understand 
why it should be more easy to extract the pepsin by acid from the 
fundus glands than the pyloric. We may regard it therefore as 
probably true that repeated extracts furnish us with a considerable 
amount of the pepsin obtainable. On the other hand, it may be asked 
how far the juices secreted into artificially isolated portions of pyloric 
mucous membrane are to be regarded as normal? It seems that in 
Heidenhain’s case there was an absence of inflammatory conditions. 
But it must be noticed that the operation performed involved very 
considerable interference with the nerve supply to that portion of the 
mucous membrane. The mucous membrane was probably, therefore, to 
some degree in an abnormal condition. Nevertheless, the fact that 
proteolytic powers were shown could not be explained by reason of 
such an abnormal state; they must probably be indicative of normal 
secretion. It seems impossible that any “infiltrated” pepsin could 
produce the enduring effect in the secretion noticed by Heidenhain, and 


1 Op. cit. 2 Op. cit. 
3“Untersuch. aus dem Gebiete der Magenverdauung,” Ungar. Arch. f. Med,, 
Wiesbaden, 1894, Bd. iii, 


536 MECHANISM OF SECRETION OF GASTRIC JUICE. 


it may be regarded as established that the pyloric glands do secrete 
pepsin. 

The results of experiments that have been made to ascertain 
whether pepsin or pepsinogen is contained in saline extracts of the 
pyloric mucous membrane, lead to the conclusion that pepsinogen 
may be present. The fact that the amount of pepsin obtainable from 
the pyloric mucous membrane is increased rather than diminished? as 
digestion advances is susceptible of one of two explanations. It may 
be that during digestion the intracellular formation is more rapid than 
the secretion, and thus an absolute increase in the pepsin contents of 
the cells occurs. Or it may be that in course of absorption of certain 
products of digestion by the pyloric mucous membrane, a certain 
amount of pepsin becomes “infiltrated” in the membrane. At any 
rate, there is something fundamentally different in this respect between 
the secretion of pepsin at the pyloric end of the stomach and in 
the fundus glands, for in the latter the amount of pepsin decreases 
as digestion advances, whilst in the former there is an increase. Nor 
is there any evident change in the histological appearance of the pyloric 
cells corresponding to a “secretory process. It is probable, as Langley 
has suggested, that the precursor of pepsin (“mesostate,” as it may con- 
veniently be called) is not so highly specialised as in the fundus glands ; 

there may be a series of mesostates, the more highly developed 
splitting off the enzyme earlier than the more lowly. The observations 
of Klug, which are confirmatory of the much older observations of 
Briicke, that a series of hydrochloric acid extracts will continue to show 
proteolytic powers, suggests that there are several mesostates of 
different grades coexistent in the cell. It is, moreover, possible that 
only in the most highly specialised mesostates does the condition of 
secretory granules obtain. From all this it appears probable that the 
formation of pepsin is a subsidiary function of the pyloric mucous 
membrane, and that it yet remains to be discovered whether the cells 
of the pyloric glands possess other more important functions. 

The methods of obtaining gastric juice.—The older observers 
obtained samples of gastric juice by causing animals to swallow hollow 
pas balls, containing pieces of sponge. In this way Réaumur,? 
Stevens? and Spallanzani 4 obtained a fluid which caused meat to 
become digested, and which was marked by antiseptic properties. 
Tiedemann and Gmelin® made fasting animals swallow pebbles, which, 
acting as mechanical irritants, permitted a certain quantity of gastric 
Juice to be secreted, and this was obtained by killing the animals shortly 
afterwards. 

Beaumont had under observation in 1822 a man who had a gun-shot 
wound in the left side. There resulted from this a permanent fistula 
into the stomach. A valve, formed of the mucous membrane, became 
established over the opening, and on depressing this, introducing a 
tube, and turning the man on his left side, a flow of gastric juice was 
obtained. 


1 See Griitzner’s chart (Fig. 44), in the section on the variations in composition of gastric 
juice during digestion. 

2 ««Sur la digestion,” Hist. Acad. roy. d. se. de (Paris), 1752. 

® “Te alimentorum concoctione,”’ Edin., 1877. 

4 “«Expériences sur la digestion de homme et de différentes espéces d’animaux,” 
Geneve, 1783. 

> “Die Verdauung nach Versuchen,” 1826. 


INFLUENCE OF NERVOUS SYSTEM. 537 


Since this time many other cases of gastric fistula in the human subject 
have been under observation.! In 1842, Bassow? and blondlot simultaneously 
introduced the method of obtaining gastric juice by an artificial fistula in an 
animal, and this method was further developed by Heidenhain,*® who introduced 
antiseptic precautions into the operation. 

Heidenhain also succeeded in so developing Klemensiewicz’s method of 
isolating one portion of the stomach from the rest, that it was possible to keep 
the animals under protracted observation in this condition. In making the 
incisions for the operation, Heidenhain interfered as little as possible with 
the more important blood vessels, but he apparently produced some disturb- 
ance as far as the connections of the main nerves of the stomach were 
concerned. 

Pawlow’s* method of isolating by operation a portion of the stomach, 
retained the advantages of that of Heidenhain, while keeping unimpaired 
the nerve distribution to the isolated portion. 


The influence of the nervous system on gastric secretion.— 
The stomach is supplied with two sets of nerve-fibres, cerebro-spinal 
and sympathetic. The vagi constitute the cerebro-spinal set, and branches 
from the solar plexus the sympathetic. The fibres of the vagi are almost 
entirely non-medullated in their course over the stomach. Plexuses 
formed by these nerves lie between the muscular and in the submucous 
eoats. The nerve-fibres are distributed to the muscular tissue, to the 
blood vessels, and to the mucous membrane, and filaments have been 
traced to terminal arborisations between and in close contact with the 
cells of the gastric glands.°® 

Many have attempted to obtain indications of the nature of the 
impulses passing along these nerves by artificial stimulation. 

Rutherford® cut the vagi during digestion, and found that the mucous 
membrane became paler. If the “peripheral ends were stimulated, no 
regular effect resulted; if the central ends were stimulated, the mucous 
membrane became redder. After division of both vagi, apparently 
normal gastric juice was still secreted. Rutherford also found that 
normal secretion occurred after division of the splanchnics. The effect 
on the blood supply of stimulation of the central end of the vagus was, 
presumably, brought about by impulses passing to the medulla oblongata, 
inhibiting the action of the vasomotor centre there, and resulting in 


1The following is a list of the principal observations on gastric fistule in man :— 
Helm, ‘‘ Zwei Krankengeschichten, ” Wien, 1803; Briicke’s ©Vorlesungen,” Baines: 
300 ; ‘Beaumont (1825- 33), ‘Experiments and Observations on the Gastric Juice and the 
Physiology of Digestion,” reprinted from the Plattsburgh edition, with notes by Andrew 
Combe, M.D., Edinburgh, 1838 ; W. Robertson, 1851 ; C. Schmidt, Diss., Dorpat, 1851 ; 
Ann. d. Chem., 1854, Bd. xeii. Kretschy, Jahres. it. d. Fortschr. d. Thier-Chem., 
Wiesbaden, 1876, Bd. vi. sh alyiaie ae ibid., 1877, Bd. vii. S. 273 ; Richet, ‘‘ Le sue 
gastrique,”’ Paris, 1878. 

2 The following is a list of the more important observations on gastric fistule in 
animals : :—Bassow, Bull, Soe. imp. d. nat. de Moscou, 1842, tome xvi.; Blondlot, ‘‘ Traité 
analytique de la digestion,” Nancy et Paris, 1843 ; ‘Bardeleben, Arch. Sf. physiol. Heilk., 
Stuttgart, 1849, Bd. viii.; Bidder u. Schmidt, “Die Verdauungssiifte,” Leipzig, 1852 ; 
Holmgren, Jahresb. ii. d. Leistung. . . . d. ges. Med., Berlin, 1860, Bd. i.; Schiff, ‘‘ Lecons 
sur la physiologie de la digestion,” Paris and Berlin, 1867, Bd. i. S. 15 ; Klemensiewicz, 
Sitzungsh. d. k. Akad. d. W issensch., Wien, 1875, Bd. Ixxi.; Panum, Jahresh. i. d. 
Fortschr. d. Thier-Chem., W iesbaden, 1878, Bd. vili. S. 193; Heidenhain, Arch. f. d. ges. 
Physiol., Bonn, 1878, Bd. xviii. S. 169 ; 1878, Bd. xix. S. 148 ; Hermann's ‘‘ Handbuch,” 
Leipzig, 1881, Bd. v. S. 107. 

‘“Anlegung von Magenfisteln,” Hermann’s ‘‘ Handbuch,” Leipzig, 1881, Bd. v. Th. 

4 The details of this method are ‘described by Chischin, Tnaug. Diss., St. Petersburg, i804 

» Kytinanov, Internat. Monatschr. f. Anat. wv. Physiol, Leipzig, 1896, vol. xiii. p. 402. 

6 Trans. Roy. Soc. Edin,, 1870, vol. xxvi. 


538 MECHANISM OF SECRETION OF GASTRIC JUICE. 


efferent impulses, dilator in character, passing along the sympathetic to 
the mucous membrane. 

That impulses passing along the vagi influence the movement of the 
stomach, and possibly by that means to some extent the secretion, has 
been shown by several observers. 

Goltz} exposed the stomach and cesophagus of two curarised frogs, 
and, after suspending them, dropped into their mouths salt solution. One, 
however, had had the brain and spinal cord destroyed. After a time it 
was found that in the complete animal the stomach and cesophagus were 
widely distended, whilst in the pithed frog they were empty. The latter 
result occurred equally well if the vagi only were cut. Stimulation of 
the vagi peripherally eaused only shght contractions. The explanation 
given ‘by Goltz of this result is that the stomach walls presumably 
contain a local mechanism w hich, under the conditions in which the 
animals were, would have undergone stimulation. The result of this 
would have been peristaltic contraction, causing the fluid to be passed on 
into the intestine. But ordinarily this is controlled by efferent impulses 
passing from higher centres along the vagi. If the controlling influence 
is destroyed, there results an exaggerated action of these centres. Goltz 
was disposed to regard this local mechanism as of a ganglionic nature. 


In connection with this question, it may be stated that Openchowski? has 
described the existence of special nerve-plexuses with ganglionic cells, both at 
the cardia and at the pylorus. He considers that the opening and closing of 
these passages are to be referred to the direct influence of these ganglia, though 
these again are under the control of the central nervous system. Openchowski 
describes a centre for the contraction of the cardia situated in the posterior 
corpora quadrigemina, and connected with the stomach mainly by the vagi. A 
centre for the opening of the cardiac orifice hes in the basal oanclia, and 
communicates with the stomach by means of the vagus. There are also 
subsidiary centres in the spinal cord influencing dilatation of the cardiac 
orifice. In the same regions are centres influencing movements of the pylorus 
and the intermediate walls of the stomach. Openchowski emphasises the 
antagonism between the movements of the cardia and the pylorus ; such nervous 
impulses as proceed down the vagus and dilate the cardiac orifice simultaneously 
close the pylorus. 


As regards the more direct influence of impulses proceeding along 
the vagi upon secretion in the stomach, for a long time the oreatest 
uncertainty prevailed, and it was held that in general such impulses did 
not directly affect secretion, but merely indirectly, through promoting 
movements of the stomach walls. Heidenhain? has suggested that, as 
mechanical irritation produced secretion from the digestive glands in the 
plant Drosera, so the direct irritation of food in the stomach might 
stimulate the gastric epithelium. There has existed for a long time, 
however, indirect evidence of a flow of gastric juice resulting from 
psychical conditions. Bidder and Schmidt + makiéed: as early as 1852, that 
the sight of food in a gastrostomised dog resulted in an abnormal flow of 
gastric quice.” To obviate any possibility of swallowed saliva causing 
this result, which saliva it was known could be secreted as the con- 

1 “<Studien iiber die Bewegung von Speiserdhre und Magen d. Frosche,” Arch. f. d. 
ges. Physiol., Bonn, 1872, Bd. vi. 

2 “Ueber die nervésen Vorrichtungen des Magens,” Centradbl. f. Physiol., Leipzig u. 
Wien, 1889, Bd. iii. 

° Hermann’s ‘‘ Handbuch,” Leipzig, 1881, Bd. v. Th. 1. 

+ “Die Verdauungssifte und der Stoffwechsel,” Leipzig, 1852. 


INFLUENCE OF NERVOUS SYSTEM. 539 


sequence of psychical conditions, oesophageal fistulee were made, and the 
saliva was prevented from passing into the stomach. 

In Richet’s! observations on a human subject, who, by swallowing a 
caustic alkali, had rendered the cesophagus impassable, and in whom con- 
sequently it had become necessary to make an opening into the stomach, 
it was observed that chewing savoury food, none of which passed into 
the stomach, produced a copious flow of gastric juice. It was not 
possible in these cases to absolutely assert that this resulted from 
nervous influence acting directly on the secreting epithelium, for move- 
ments of the stomach may have brought about the flow, but the quan- 
tity secreted suggested a direct nervous influence. That there is such 
a direct nervous influence has been conclusively proved by Pawlow,? 
in conjunction with Schoumow-Simanowsky. Their experiments were 
made on dogs which had had a portion of the stomach isolated in the 
manner already described, care being taken that the nervous connections 
were intact. In addition, the esophagus was separated, the cut ends 
being attached to openings in the neck, so that swallowed food passed 
out at one opening, and, through the other, food which it was desired 
should enter the stomach could be passed in. It was possible, therefore, 
to bring the animal under the influence of food in three ways. In the 
first place, it might be shown food, but the food would not be actually 
introduced into the stomach. This constituted the so-called “ psychical 
feeding.”* Secondly, the animal might be fed by the mouth, but none 
of the food allowed to enter the stomach, since it would make its exit 
at the cesophageal opening. This was described as “ pseudo-feeding ” 
(Scheinfiitterung). Thirdly, by the introduction of food into the lower 
division of the cesophagus, true feeding was carried on. The results 
yaried according to the method adopted. The latent period, or period 
elapsing after administration before secretion commences, is in the dog 
about seven minutes. This does not vary much whether it be a case of 
psychical, pseudo-, or true feeding. The latter course of secretion shows, 
however, considerable variations. This was the first point established 
by Pawlow. 

He next attempted to discover the paths of the nervous impulses 
bringing about these changes. Section of the splanchnics did not 
affect the results, but after severing both vagi the reflex secretion 
was absent. With one vagus cut (the right), the animal was found to 
respond in the usual way. Later the left vagus was divided without 
anesthesia. The animals live for a few days in this condition, but 
during this time no reflex secretion occurs. From this it was concluded 
that the impulses constituting the efferent portion of the reflex act pass 
along the vagi. But more positive results in this connection were 
obtained by Pawlow by stimulating the peripheral ends of the cut vagi. 
If, some twenty-four hours after the second section, the cut end be stimu- 
lated—and it is better to do this by applying induction shocks at the 
rate of one per second, rather than by using the rapidly interrupted 


1 «Te suc gastrique chez l’homme et les animaux,” Paris, 1878. 

2 <¢ Die Innervation der Magendriisen beim Hunde,” Arch. f. Physiol., Leipzig, 1895. 

3 Though the exhibition of food to the dog, which had been operated on in the manner 
described above, evoked a flow of gastric juice, if, from previous experience, the dog was led 
to understand that the food would not actually be given, the secretion very soon stopped. 
It may be mentioned that Heidenhain did not regularly obtain a flow as the result of 
showing the animal food, and this suggests that his method involved interference with the 
-hervous tracts, 


540 MECHANISM OF SECRETION OF GASTRIC JUICE. 


current,—there results a flow of gastric juice. A certain interval occurs 
before the secretion is manifest, which is to be referred to changes 
actually taking place in the epithelium of the stomach. The character 
of the secretion varies according to the stage of the digestive act and the 
nature of the food. This will be again referred to in a later section. 


It must be mentioned that some observers have not had the same success 
in showing the secretory importance of the vagus nerve. That certain differ- 
ences are perceptible in consequence of its excitation, they admit, but they 
refer the variations rather to the altered power of muscular contraction 
possessed by the stomach. Thus Leubuscher and Schifer! experimented 
both upon rabbits and dogs, performing the operations according to Pawlow’s 
method. They frequently used a control animal for precision in estimating 
the change. As far as variations in the amount of hydrochloric acid were 
concerned, they came to the conclusion that there was no constant difference. 
The stomach they found invariably relaxed, and the food introduced within 
was, after a prolonged interval, found to be arranged in two zones, one against 
the walls of the stomach, which was well digested and contained hydrochloric 
acid in normal amount, that occupying the centre of the viscus being poor in 
acid and rapidly becoming decomposed, As far as stimulation of the peripheral 
stump of the vagus was concerned, they did not obtain constant results, but 
they appear to have adopted the rapidly interrupted current rather than the 
induction shocks at prolonged intervals used by Pawlow. That the food was 
not perfectly mixed, is obvious from their experiments. This will probably 
explain the decomposition occurring ; this change was noticed also by Pawlow to 
come on a few days after section of both vagi. It is, however, to be noted that 
they were unable to confirm the passage of secretory impulses along the vagus. 

There exists one observation upon the human being from which it seems 
that stimulation of the vagus may cause a flow of gastric juice. Regnard and 
Loye ? stimulated the vagus in a decapitated criminal some forty-five minutes 
after death. Numerous drops of gastric juice appeared over the surface of the 
stomach. This may also, however, have been the result of movements of the 
stomach, which they observed at the same time to occur. 


The conditions under which local stimulation provokes secre- 
tion.—As already stated, it has been held by many that simple 
mechanical irritation of the mucous membrane will directly produce a 
flow of gastric juice. Beaumont? showed that mechanical irritation of 
the mucous membrane caused increased vascularity and the appearance 
of small drops of gastric juice, and he further pointed out that the effect 
is confined to the irritated locality, and that the amount of juice secreted 
is small in quantity. Tiedemann and Gmelin,t Heidenhain, and 
others also state that the secretion is limited. Pawlow® states that 
the amount secreted is practically nothing, when indigestible substances 
such as pebbles are placed in the stomach. It may therefore be 
regarded as probably true that any secretion produced by simple 
mechanical irritation is extr emely small, and the existence of this shght 
secretion in no way suggests that the normal secretion can be looked 
upon as the result, to any great extent, of such stimulation. On the 
other hand, stimulation by food, even if solid, is much more effectual. 

1 ««Ueber die Beziehungen des Nervus Vagus zur Salzsiiure-secretion des Magenschleim- 
haut,” Centralbl. f. innere Med., Leipzig, 1894, Bd. xv 

> «Recherches faites a Amiens sur les restes d’un supplicié,” Compt. rend. Soc. de biol., 
Paris, 1887. 

3 Op. cit. tO pace. 5 Arch. f. d. ges. Physiol., Bonn, 1879, Bd. xix, 

5 Address at St. Petersburg. Reported in Brit. Med. Jowrn., London, 1895. 


INFLUENCE OF LOCAL STIMULATION. 541 


Heidenhain found that following a latent period of some fifteen minutes 
after placing food in the organ, the stomach commenced to secrete gastric 
juice. This delay beyond the interval observed in Pawlow’s experiments 
was presumably due to a certain amount of injury to the nervous 
connections. If indigestible substances were swallowed, the secretion 
was much longer delayed. The conclusion which Heidenhain arrived 
at was that certain products of digestion when absorbed stimulate the 
flow of gastric juice. The question then arises, What are these products 
of digestion, and by what paths are they absorbed? Are the completely 
digested foodstufis (that is to say, completely digested as far as gastric 
digestion is concerned) passed on to the intestine and there absorbed, 
or are they directly absorbed in the stomach ? 

As regards the change undergone by different proteids when subject 
to gastric digestion, there is reason to believe that the stage reached 
in the stomach is not a final one, some further change taking place 
in the duodenum, and that the amount of peptone formed in the 
stomach may not be large, the proteose stage being, to a great 
extent, the final stage of gastric digestion. If this is so, and if 
the secretion from the gastric mucous membrane is influenced by 
absorbed peptones, it must be influenced by peptones absorbed in 
the small intestine. On the other hand, we are unable to state 
definitely to what extent the intermediate results of the digestion 
of proteids are absorbed in the stomach. As regards the carbohydrate 
foodstuffs, v. Mering! has shown that sugars are absorbed by the 
stomach. If it is absorbed digestive products that provoke the 
secretion, is it a specific product or products that cause this to occur, or 
is it a common characteristic of all? Chischin? has attempted to 
answer this question. He finds that feeding a dog (which has had 
a portion of its stomach isolated after the manner of Pawlow) with 
different varieties of food, results in very different characters being 
shown by the secreted juice during the course of digestion, and he 
hence infers that there must be some specific stimulus or stimuli 
influencing the secretion. The different substances were administered 
in such a manner as to avoid the “ psychical” influence on the secretion. 
The administration of distilled water, gastric juice, or simple hydro- 
chloric acid, caused but little change. Egg-albumin, sugar and starch 
solution, were tested with the same negative results. The administra- 
tion of peptone, however, resulted in a pronounced secretion. Chischin 
considers that peptone was not only able to cause the gastric mucous 
membrane to become active, but also to sustain it im activity. If egg- 
albumin be administered so as to evoke the psychical influence, a well- 
marked and sustained secretion resulted. Chischin accordingly explains 
the usual process of secretion as occurring in the following manner :—At 
the time of taking food the first flow of gastric juice is determined by 
the reflex psychical influences involved in taking food. The digested 
proteids are able later to evoke a secretion, at a time presumably 
when the psychical influence begins to wane. 

According to these experiments, then, we may assume that small 
quantities of peptone may be normally formed in the stomach, and, 


1“eber die Function des Magens,” Verhandl. d. Cong. f. innere Med., Wiesbaden, 
1893. 

2 Inaug. Diss., St. Petersburg, 1894. Reported in Jahresb. ii. d. Fortschr. d. Thier- 
Chem., Wiesbaden, Bd. xxy. 


542 MECHANISM OF SECRETION OF GASTRIC JUICE. 


becoming absorbed there, in some way influence the epithelium so that 
secretion results. The exact course of this absorption is a matter of 
some difficulty as far as the secretory epithelium is concerned, but it is 
yet more difficult to comprehend how peptone absorbed and changed in 
the intestinal wall should influence secretion in the stomach. If, as 
Schiff? long ago suggested, the absorption of these products should assist 
in building up the precursor of pepsin, we could more easily see the 
importance of these products passing to the secreting cells. Schiff, 
however, emphasised dextrin as being pre-eminently a “ peptogenous ” 
substance. Chischin finds that it does not evoke secretion. 

The conditions of formation of the ferments of the gastric juice. 
—(a) The conditions of the formation of pepsin.—As previously men- 
tioned, Briicke? had noticed that the pepsin present in the gastric 
mucous membrane was not yielded entirely to one extraction, and 
Ebstein and Griitzner * pointed out that the peptic activity depended 
considerably upon the manner in which an extract was prepared. An 
extract made by treating the gastric mucous membrane with hydro- 
chlorie acid was much more powerful than one obtained by subjecting 
the mucous membrane to the action of glycerin. That which was not 
extracted by glycerin, Ebstem and Griitzner regarded as a compound 
of pepsin with the proteid matter of the cells, this compound yielding 
pepsin on subjection to the influence of acid, or to the action of sodium 
chloride. Schifft had also remarked, that if a dilute acid be added to 
the stomach and left for some weeks, the extract becomes gradually 
richer in peptic activity. Schiff accounted for this by assuming the 
existence of a precursor of pepsin in the cells of the mucous membrane, 
which gradually became converted into pepsin by the acid. This he 

called propepsin. In both cases the observers were dealing undoubtedly 
with some substance which yielded pepsin, and to this substance the 
name pepsinogen has since been applied. Ebstein’s and Griitzner’s 
test for the existence of this substance was the fact that it was not 
dissolved by glycerin as was pepsin, and yet would yield pepsin on 
treatment with acid. but it was soon found that there were difficulties 
in differentiating pepsin from its precursor in this manner. Von Wittich® 
poimted out that when fibrin is placed ina glycerin extract of pepsin, 
the fibrin absorbs the pepsin, and will only yield it again to fresh treat- 
ment with acid. Ebstein and Griitzner® further showed that even 
coagulated egg-albumin would do this. Thence it followed that the 
proteids of the gastric mucous membrane might fix the pepsin, and that 
a olycerin extract of the mucous membrane might be an extract of such 
pepsin as was not fixed by the proteids. It was necessary, therefore, to 
tind some more definite test of the presence of pepsinogen. This was 
supplied by Langley,’ who found that sodium carbonate had a power- 
fully destructive effect on pepsin, but a much less marked action on 
certain extracts of the mucous membrane from which pepsin could be 
derived. These extracts, therefore, were held to contain the zymogen. 
He also inferred that the gastric glands contained the ferment in the 
zymogen state, as they did not contain any appreciable amount of 

1 «Tecons sur la physiologie de la digestion,” 1867, tome ii. 

= Noresam en 1874. 

3 Arch. f. d. ges. Physiol., Bonn, 1874, Bd. viii. 4 Thid., 1877. 

5 Tbid., 1872, Bd. v. ; 1873, Bd. vii. 6 Op. cit. 


7 «The Histology of the Mammalian Gastric Glands, and the Relation of the Pepsin 
to the Granules of the Chief Cells,” Journ. Physiol., Cambridge and London, 1882, vol. iii. 


FORMATION OF FERMENTS OF GASTRIC JUICE. 543 


pepsin, but would yield the same under appropriate treatment. The 
differentiation of the one from the other was further advanced by 
Langley and Edkins.!. They confirmed the observation, that alkalies 
and alkaline salts rapidly destroy pepsin. The conditions influencing 
the rate of destruction by sodium carbonate were found to be the 
strength of the solution of the alkaline salt, the time during which it is 
allowed to act, the temperature of the mixture, and finally the amount 
of proteids present. By mere neutralisation of an acid solution of 
pepsin, a considerable amount might be destroyed. If equal volumes of 
an extract of pepsin and of a 1 per cent. solution of sodium carbonate 
were mixed, in fifteen seconds as much as 97 per cent. of the pepsin 
might be destroyed. The greater the amount of proteid present, the 
ereater the amount of sodium carbonate necessar y to cause destruction. 
The difference between pepsin and pepsinogen in their behaviour with 
different reagents is merely one of degree. Pepsinogen is destroyed 
also by alkalies, but the destruction is so slow as compared with that of 
pepsin, that this reaction furnishes a useful method of distinguishing 
the one from the other. Since the aqueous extract of the gastric 
mucous membrane of a fasting animal loses but very little ‘peptic 
power on brief treatment with 1 per cent. sodium carbonate, it follows 
that pepsinogen, but little or no pepsin, is present in the gastric glands 
in hunger. Schiff stated that “propepsin” was slowly converted into 
true pepsin. Langley and Edkins found that the conversion of 
pepsinogen into pepsin is one of great rapidity. All the pepsinogen 
present in an aqueous extract of a cat’s gastric mucous membrane 
may be converted into pepsin by treatment with 1 per cent. hydro- 
chlorie acid in sixty seconds. With reference to the point as to 
whether pepsin is present in the gland cells during digestion, no definite 
result was arrived at. Pepsi can be obtained from the gastric 
mucous membrane of an animal in digestion, but not invariably, and 
such as is found may have been produced by the acid in the lumen of 
the tubes affecting the pepsinogen in the contiguous chief cells. In the 
cesophagus of the frog, where no acid is secreted, but only ferment, 
injection of commercial peptone causes no accumulation of pepsin in 
the gland cells. Carbonic acid destroys pepsinogen more rapidly than 
pepsin; but if only a small quantity of peptone is present, there is 
practically no destruction. Finally, it is observed that both pepsin and 
pepsinogen are rapidly destroyed on heating to a temperature of 55°— 
57° C. 

(0) The conditions of formation of rennin (rennet-ferment).—An enzyme 
which has the property of causing milk or the separated caseinogen 
to undergo coagulation, is found in the stomachs of almost all animals. 
As regards the secretion of rennin, there is an important resemblance 
to that of pepsin, masmuch as, in the case of the former, there is a 
precursor of the actual ferment existent in the glands of the stomach 
which has the power, under the influence of acid, of producing the 
active enzyme. It was in the case of the rennin that it first was 
shown that many of the ferments of the alimentary canal have a 
zymogen stage. Hammarsten,? in 1872, poimted out that the gastric 
glands of many animals contain rennet-zymogen, but do not contain 
rennet- ferment. The zymogens of pepsin ‘and trypsin were not 


1 «Pepsin and Pepsinogen,” Journ. Physiol., Cambridge and London, 1886, vol. vii. 
2 Jahresh. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1872. 


544 MECHANISM OF SECRETION OF GASTRIC JUICE. 


described till some years later. Langley’ showed that the method of 
separating pepsin from pepsinogen was applicable also to the rennin, 
since rennet-ferment was destroyed by sodium carbonate, whilst rennet- 
zymogen is affected much less powerfully. Hammarsten has also shown 
that the amount of rennet-ferment that can be extracted from the 
cardiac end of the stomach is proportionally much greater than that 
obtainable from the pyloric mucous membrane. Grutzner? has shown 
that in the gastric glands of the dog, the rennet-ferment diminishes in 
amount during digestion, and that the amount of diminution runs 
parallel to that of pepsin. It seems that where pepsin is greatest in 
quantity, there also is rennet-ferment most abundant, and it seems 
probable that the granules of the chief cells contain the zymogens both 
of rennet-ferment and pepsin. We cannot say whether the granules are of 
one kind or whether there are separate forms of granules for the separate 
ferments. But though in general the zymogen of the rennet-ferment, 
and not the actual ferment, is existent in the gastric cells, yet in 
some cases, e.g. the calf and sheep, the zymogen is presumably in a 


Ole?) = 42r6l 81012) 142) 16708 Ve0;22) 1242625 ORS? 34 


Fic.44.—The figures at the abscisse on the base line refer to the 
number of hours elapsed since the last meal. The length of the 
ordinates indicates the amount of pepsin yielded at any time. F is 
the record of variation in the fundus mucous membrane, P of 
variation in the pyloric mucous membrane.—After Griitzner. 


much less stable condition, for a watery extract of the stomach of 
these animals yields rennet-ferment in large quantities. As regards 
the differentiation of the rennet-ferment from the proteolytic, they can 
be separated from one another by chemical means, although we have 
no morphological signs of their distinction. Hammarsten’s method of 
separating the two ferments chemically depends upon the fact that 
the gradual addition of lead acetate precipitates the pepsin sooner than 
the rennin.® 

The variations in the amount and composition of gastric juice 
during the course of digestion.—The amount of pepsin that can be 
extracted from the mucous membrane has been estimated by Gritzner.‘ 
He compared concurrently that obtained from the fundus with that 
yielded by the pyloric region. In the above chart (Fig. 44), which shows 
the chief variation during the lapse of some hours after a meal, the most 

1 On the Destruction of the Ferments of the Alimentary Canal,” Journ. Physiol., 
Cambridge and London, 1882, vol. iii. 

2 Arch. f. d. ges. Physiol., Bonn, 1878, Bd. xvi. 

8 The conditions of formation of the hydrochloric acid of the gastric juice are treated 
of in a preceding article (see pp. 351 et seq.). 

4 Arch. f. d. ges. Physiol., Bonn, 1879, Bd. xx. 


VARIATIONS IN GASTRIC JUICE DURING DIGESTION. 545 


striking feature is the absence of coincidence between the pepsin con- 
tents of the pyloric and the fundus region of the stomach. 

In general, it may be pointed out that the maximal yield of pepsin 
from the pyloric region is at the same interval after ingestion of food as 
marks the minimal yield of pepsin from the fundus. 

A great number of observations have been directed to estimating the 
acidity of the contents of the stomach at different intervals after a meal 
has been taken. Gastric juice commences to be secreted almost as soon 
as suitable food enters the stomach. For a time the acid juice merely 
neutralises the alkalinity of the food and saliva, and the hydrochloric 
acid combines with various food substances, so that free hydrochloric 
acid does not occur till after an appreciable interval. Von den Velden? 
states that free hydrochloric acid 
cannot be detected until three- 


= 
quarters of an hour after a meal =” 
is taken. Richet? states that in £° 
the human stomach the acidity =7 
gradually increases during diges-  § 3 
tion, and that it is apparently = 
independent of the quantity of °* 
fluid taken. Towards the end §° 
of digestion he finds that the &* 
total acidity of the stomach con- &" 
tents may be further increased, ° i Se a Pe 


but this is to be referred to the AUREL Tee Oi Cer Coney ies SL 


- : = ae , Fie. 45.—Chart showing acidity of gastric 
y Ve € ee = Eo. =e > - 
Econ of en ae Bas Sa i juice after feeding with mixed food (300 


the decomposition of the food. c.c. milk, 50 grms. meat, and 50 grms. 

He also points out that the feebler white bread). The animal was not sub- 

the activity of the juice, the jected to the ‘‘ psychical stimulation” of 
3 2 the food. 


greater the amount of organic 
acid liberated. Chischin’s? observations give precise details of the course 
of digestion with different foods. The annexed diagram (Fig. 45) shows 
the course of the production of hydrochloric acid in an isolated portion 
of the fundus, when the animal was fed with mixed food, comprising 
milk, meat, and bread. The animal did not undergo the “ psychical” 
stimulation of the food, or the maximal percentage of hydrochloric acid 
would probably have been in the first hour, instead of in the second or 
third. If meat alone be given to such an animal under similar conditions, 
the maximal acidity occurs in the first hour. With mixed food the digest- 
ive power averages 3°5 mm. (Mette’s method of estimation by columns 
of coagulated egg-white);4 with simply meat food, about 4 mm. With 
bread alone as food, the duration of secretion was found to be more 
protracted, but the digestive strength was much greater, varying between 
5°22 mm. and 756mm. The digestive power was very marked in the 
first hour, increased further in the second hour, and remained high both 
in the third and fourth hours. With milk, the course of secretion 1s 
much more irregular. The digestive power is moderately high at first, 
but sinks, after the first hour, about one-half. It remains at this 
strength for the third and fourth hours, but in the fifth hour increases 
again to the original strength, and may, in the sixth hour, even go 


1**Zur Lehre von der Wirkung des Mundspeichels im Magen,” Zéschr. f. physiol. 
Chem., Strassburg, 1879, vol. iii. . 
* Op. cit. 3 Op. cit. 4 For Mette’s method, see p. 325. 


VOL. 1.—35 


546 MECHANISM OF SECRETION OF PANCREATIC JUICE. 


beyond this. In another series of experiments the animals were fed 
with peptone (Chapoteaux). This, according to Chischin, was equivalent 
to reviewing the later stages of digestion, from the time when peptone 
began to be formed in any quantity in the stomach. ‘The noticeable 
point about the results in these last cases is, that there is presented a 
great contrast to feeding with such a primary proteid as egg-albumin. 
With peptone, the juice becomes secreted in large quantities at once, 
its acidity is high, and its digestive power well marked. 

It is obvious, therefore, that the nature of the food has an important 
influence on the course and nature of the secretion. This has been 
drawn attention to by Khigine, who classes the different foods 
mentioned above in different orders. He has also pointed out that the 
amount of juice secreted is not necessarily proportional to its acidity 
or its digestive power. These, again, are not necessarily proportional 
to each other, as is shown in the case of bread as food, when a low 
acidity im the secreted juice is shown, but a high degree of peptic 
power; whereas with milk a high degree of acidity is shown, but a much 
lower degree of digestive power. Finally, the duration of the digestive 
process is out of all relation to the strength of the secreted juice. It is 
impossible, then, to draw up any regular scheme of the course of digestion, 
except so far as specific foods are concerned, observations based upon the 
course of digestion of foods mixed in arbitrary proportions being of but 
little value. 


THE MECHANISM OF PANCREATIC SECRETION. 


The histological appearances of the different secretory condi- 
tions of the pancreas.—The pancreas consists of secretory alveoli, 
between which are here and there seen masses of cells of a different 
character, and having no connection with the proper secretory channels 
of the gland. These masses of cells are presumably not connected with 
the ordinar y processes of the secretion of a digestive juice, and the follow- 
ing account will therefore be confined to the 1 typical secretory alveoli. 

If a small portion of the pancreas of an animal be examined in the 
living state, it will be found to consist of many secretory alveoli, and 
these secretory alveoli of cells contain numbers of discrete granules. 
It is generally found that whatever digestive stage the animal is in, there 
exists an outer zone in the alveolus free from granules. This is not, 
however, invariably the case. Ordinary stains, “such as hematoxylin 
and carmine, are found to colour this outer zone more deeply than the 
rest. This is in conformity with the usual rule, that such stains do not 
deeply colour the secretory granules of cells, or the substance formed by 
their breaking down. If the cells are macerated for a few days in 
neutral ammonium chromate, a radial fibrillation is revealed? in this 
outer zone. The addition of water to the fresh gland causes the 
sranules to disappear, and dilute alkalies produce this result even more 
rapidly. Acids, either mineral or organic, cause the distinction between 
the two zones to be lost, the whole cell becoming clear. By hardening 
the gland in solutions of osmic acid, or in the vapour of osmic acid, the 
granules may be preserved. 

1 Etudes sur lexcitabilité sécrétoire specifique de la muqueuse du canal digestif” 


Arch. de sc. biol., St. Pétersbourg, 1895, vol. iii. p. 5. 
2 Heidenhain, Hermann’s ‘‘ Handbuch,” Bd. vy. Abth. 4. 


METHODS OF OBTAINING PANCREATIC JUICE. 547 


Although, in the resting condition of the gland, an outer border free 
from granules is evident, this is still more manifest in the exhausted 
condition. The granules may then be so reduced in number as to form 
small aggregations at the luminal borders only of the cells. 

As is the case in the stomach, there is reason to believe that the 
granules are concerned with the specific secretion of the gland, the 
amount of granules determining the activity of an extract. 

The above described changes in the cells were first observed in the 
living pancreas of the rabbit by Kiihne and Sheridan Lea.! 


Methods of obtaining pancreatic juice.—The methods that have been 
adopted to procure a supply of pancreatic juice involve one of the following 
procedures—(a) Fixing a cannula into the duct of Wirsung ; (4) opening the 
duct and connecting it with the body wall; (c) cutting out a piece of the 
intestine in which the pancreatic duct opens, and fixing this to the body 
wall. 

C. Bernard ? adopted the first method, fixing a silver cannula into the duct. 
Heidenhain * introduced antiseptic precautions into the operation. He made 
an incision in the linea alba midway between the xiphoid process and the 
umbilicus. The duodenum was drawn out through the opening and the duct 
carefully sought for. This being found, into it was tied a glass cannula 
of about 6-18 cms. in length. Around the intestine were placed two 
temporary ligatures, keeping the gut closely applied to the body wall. The 
opening was found to gradually close, allowing simply the cannula to pass 
through. ‘The second method was adopted by Ludwig with Weinmann,‘ and 
Bernstein.® They found and opened the duct and inserted a piece of lead wire, 
on the one hand, towards the papilla pancreatica in the duodenum, the other 
end passing up to the gland substance. This wire did not fill the lumen, and 
thus the flow was still permitted. The third method, which is due to Heidenhain 
and adopted for permanent fistulee, consists in resecting the small portion of the 
intestine which contains the papilla pancreatica, and joining the ends of the 
main gut above and below. The piece of intestine is slit up, the mesenteric 
surface is attached to the body wall, and thus the juice can be obtained. 
Pawlow varied this method by not resecting the whole tube of the intestine. 
He cut out a quadrangular piece, including the pancreatic papilla, and ligatured 
this into the body wall. 

By these different methods natural pancreatic juice may be obtained. 
After a time the juice becomes somewhat altered; it retains, however, its 
ferment activity in a marked manner throughout. 


The influence of the nervous system upon pancreatic secretion. 
—Our knowledge has lately been considerably extended in respect of 
the precise influence of nervous impulses upon pancreatic secretion. 
The following statements summarise our chief knowledge up to the 
most recent researches upon the subject.® 

1. After division of the nerves, proceeding to the gland, secretion is set 
up and apparently increases. This was affirmed by Bernstein.’ 

2. Secretion can be set up by stimulation of the medulla oblongata, 
or, if already in progress, can be increased.® 

3. The medulla oblongata must not be regarded as exclusively the 


1 Verhandl. d. naturh.-med. Ver. zw Heidelberg, N.F., Bad. i. 
2 “Mémoire sur le pancréas et sur le rdle du suc pancréatique,” Compt. rend. Acad. d. se, 
Paris, 1856. 


3 Hermann’s ‘‘ Handbuch,” Bad. v. 4 Zischr. f. rat. Med., Bad. iii. 
° Ber. d. k. stichs, Gesellsch. d. Wissensch., Leipzig, 1869. : : 
§ Cf. Heidenhain, Hermann’s ‘‘ Handbuch,” Bd. v. Abth. 4. ODP Ci. 


8 Heidenhain, Arch. f. d. ges. Physiol., Bonn, 1875. 


548 MECHANISM OF SECRETION OF PANCREATIC JUICE. 


centre for pancreatic secretion, as, after its separation from the cervical 
spinal cord, the secretory process can continue, although with diminished 
intensity. 

4, The nerves proceeding to the pancreas do not seem to have the 
same direct influence upon the secretion that the nerves to the salivary 
glands possess. 

5. Stimulation of the central end of the divided vagus, according to 
Bernstein, or of sensory nerves in general (e.g. cutaneous), according to 
Afanassiew and Pawlow,? may inhibit the secretion, provided the pan- 
creatic nerves are intact. This, Heidenhain regards as due to vascular 
changes. 

Pawlow? found that the administration of atropine stopped the 
secretion frequently, but not in all animals (eg. m dogs but not in 
rabbits), and Heidenhain observed that the administration of pilocarpine 
caused a sluggish secretion of a concentrated juice. 

The later experiments of Pawlow and the St. Petersburg school have 
greatly amplified our knowledge of the nervous influence. In Pawlow’s 
further researches he observed the effects of nerve stimulation upon dogs 
prepared for experiment in two different ways. In the first case the 
dog had a permanent pancreatic fistula prepared, one vagus in the neck 
was also divided. The stimulation of the peripheral stump of the vagus 
was performed some five days after the section, at a time when certain 
fibres in the vagus had degenerated. In the second case the vagus was 
cut through in the neck, and after three or four days the animal was 
prepared for experiment by the performance of tracheotomy, section of 
the spinal cord just below the medulla oblongata, and the preparation of 
a fresh pancreatic fistula. In both these cases stimulation of the peri- 
pheral end of the vagus causes secretion from the pancreas. Moreover, 
stimulation of the intact vagus also produces this result, and even if 
neither vagus is divided a more or less pronounced secretion ensues. 
Certain differences are observable, however, between the general effects im 
the two cases. In the first case more secretion was produced, this being 
comparatively watery in character and greatest im amount at the 
commencement of stimulation. These differences are probably accounted 
for by the general low blood pressure in the second case. The pressure 
of the secretion was found by Pawlow to be lower than the corresponding 
blood pressure, and it was noted that vagus stimulation im one case still 
caused a secretion, although the blood pressure was reduced by bleeding 
practically to ml. Frequently the secretion would end with the lowering 
of the blood pressure, but nevertheless the one experiment is sufficient 
to establish the independence of the secretion of the blood pressure. 
The action of atropine is to cause a marked influence on the effects 
of nerve stimulation, though complete cessation of the secretion is not 
produced. Reflex effects can be produced on the secretion, which do not 
correspond to the effects upon the blood vessels. Stimulation of the 
central stump of the lingual or of the vagus nerve will produce such reflex 
effects. If, at the commencement of the experiment, either no secretion 
or a slight secretion occurs, with the first stimulation of sensory nerves 
either a commencement or an increase of the secretion results. After 
the stimulation ceases this lessens. If after the first stimulation the 


1 Ber. d. k. stichs. Geselisch. d. Wissensch., Leipzig, 1869. 
2 Arch. f. d. ges. Physiol., Bonn, 1878, Bd. xvi. 
3 Arch. f. Physiol., Leipzig, 1898, Supp. Bd. 


INFLUENCE OF NERVES ON PANCREATIC SECRETION. 549 


secretion is still fairly marked, a further stimulation will result in 
inhibition of the secretion, which inhibition ends with the stimulation 
provoking it. The spontaneous secretion that is sometimes observed 
before the experiment begins, is stopped by cutting both vagi, and is 
therefore due to impulses proceeding from the upper portion of the 
cervical spinal cord or the medulla oblongata. Pawlow also points out 
the importance of the circulation in general for the secretion. A brief 
stoppage of the blood stream caused a cessation of the flow, and an 
anemic condition of the gland resulting from reflex nervous influence 
caused a similar cessation. The latent period relapsing before the 
secretion resulting from stimulation becomes obvious, is, according to 
Pawlow, two to three minutes, but later observers such as Mette! and 
Kudrewetzky? regard it as somewhat longer, namely, from four to six 
minutes. Mette in addition found that, though previous observers 
(Lewaschew, Heidenhain) had stated that the proteolytic ferment failed 
in the pancreatic juice of dogs which had fasted five or six days, yet it 
was continuously obtainable by stimulation of the vagus. Gottlieb 3 

confirms the old observation, that stimulation of the divided vagus at the 
central end causes inhibition of the secretion, and he refers this result to 
general spasm of the abdominal blood vessels. Another contribution to 
the study of the inhibitory influences on the pancreatic secretion has 
recently been made by Popielski# It had been previously noticed by 
Mette and Kudrewetzky that the secretion caused by stimulating one 
vagus could frequently be stopped by stimulating the other vagus. 
Hence it was inferred that antagonistic fibres passed in these nerves. 
Stimulation of such fibres may bring about sometimes a lengthened 
latent period, sometimes total inhibition of the flow. Mette regarded 
this as due to the existence of vaso-constrictor fibres, Kudrewetzky 
to the presence of specific fibres inhibiting the secretion. Popielski 
endeavoured to elucidate this point. He found that a secretion evoked 
by peripheral stimulation of the vagus could later, by a repetition of 
the stimulation of the same nerve, be interrupted. The interruption 
started some seven seconds after the stimulation commenced, and 
lasted about the same interval beyond the cessation of stimulation. 
This inhibition also follows from stimulation of the other vagus, as 
previously observed, and is best shown when the exciting current 
is not too strong. The branch of the vagus which lies behind the 
cesophagus in the thoracic cavity is that concerned with changes in 
the secretory activity of the pancreas. Dolinski® had previously 
observed that the introduction of acids into the duodenum produces 
a flow of pancreatic juice (see next section). Popielski made use of 
this fact to see how far the secretion thus excited could be inhibited 
by nerve stimulation. He found that a secretion so produced 
was inhibited with perfect regularity by stimulation of the vagus. 
Stimulation of the vagus, after secretion evoked by pilocarpine, pro- 
duced the same result. Popielski points out that there are three 
ways in which inhibition of the flow of pancreatic juice can be brought 
about— 

1. By stimulation of vaso-constrictor fibres. 


! Arch. f. Physiol., Leipzig, 1894, Supp. Bd. 2 Thid., 1894. 
3 Arch. f. exper. Path. uv. Pharmakol. , Leipzig, 1895, Bd. xxxiii, 

4 Centrailbl. f. Physiol., Leipzig u. Wi ien, 1896, Bd. x. 

° Arch. de se. biol., St. Pétersbourg, 1895, vol. ili, 


550 MECHANISM OF SECRETION OF PANCREATIC JUICE. 


By constriction of the lumen of the duct, resulting from contrac- 
tion of its smooth muscle. 

3. By action of special nerve-fibres inhibiting secretion. 

The first hypothesis is improbable, since stimulation of the splanchnies 
does not cause the same cessation; and, moreover, there is reason to doubt 
the existence of vaso-constrictor fibres in the vagus.! 

The second hypothesis will not hold, when it is considered that 
physostigmine produces duct constriction, but at the same time increases 
the secretion. 

Before examining in detail the third supposition, Popielski endeavoured 
to see how far special secretory fibres can be anatomically isolated. Hi 
the larger branches of the vagi lying on the stomach, or those branches 
which pass towards the liver, be divided, stimulation of the vagus has the 
same influence upon pancreatic secretion. The impulses pass therefore 
along some of the finer nerve branches running in the subserous coat 
towards the pyloric region of the stomach. If the duodenum be cut 
through near the pylorus, stimulation of the vagus has no effect. If 
the duodenum be cut across lower down, the vagus effect is apparent. 
Stimulation of the lower cut edge of the duodenum in the first case 
provokes secretion, and if the main mass of nerves passing with the vein 
into the gland be stimulated (especially those lying at the upper side of 
the vein), a secretion is evoked without marked latent period, and 
uniform in character. This secretion is inhibited by the simultaneous 
stimulation of the vagus in the thoracic cavity. The inhibition comes 
about, then, either by impulses passing along nerve-fibres to the gland- 
cells, or affecting some herve-centre. Popielski finds that if the vagi 
and sympathetic nerves be cut, a reflex secretion is still evoked by 
placing hydrochloric acid in the duodenum. The reflex centre, he thinks, 
then, must be in the abdominal cavity. He considers it probable that 
such a centre exists in the region of the pylorus, since, if the duodenum 
be cut through near the py lorus, the introduction of hydrochloric acid is 
then without effect. If the pylorus be separated with the duodenum, 
hydrochloric acid will then, however, have the usual effect of causing 
pancreatic secretion. Popielski considers, however, that such a reflex 
centre is not furnished by the semilunar ganglion. 

If these observations are correct, we can assume the existence of 
secretory and inhibitory nerve-fibres, both running in the vagi, and it 
seems probable, from the differences of latent period which result from 
stimulation in different regions, that the inhibitory impulses passing 
along the vagus do not act directly on the cells of the gland, but on 
some centre w vhich. has a controlling influence on the process ; of secretion. 
Popielski’s reasons for regarding the semilunar ganglion as probably not 
furnishing such a centre, seem insufficient. The fact that Bernard found 
an increased secretion after extirpating this, can be explained, on the 
analogy of the salivary gland, as a paralytic secretion. There is some 
evidence that the inferior mesenteric ganglion may also act as a centre 
for reflex action, and if so, it seems less improbable that a similar reflex 
centre for the pancreatic secretory processes may be referred to the 
semilunar ganglion. Should such a centre exist, it is undoubtedly 
subject to influences proceeding from the higher centres by means of the 
vag. 

Though there is difficulty in admitting the existence of a controlling 


1 Francois-Franck. 


EFFECT OF LOCAL STIMULATION. oh 55 
centre for the pancreatic secretion in the semilunar ganglion, there is 
even greater difficulty in associating such a centre with any other 
neighbouring structure, or in admitting that, as Popielski considers, it 
may be placed in the walls of the pylorus. 

The conditions under which local stimulation provokes the 
flow of pancreatic juice.—As stated in the last section, a secretion 
of the pancreatic’ juice, dependent upon integrity of the nerve connec- 
tions, can be brought about by the action of certain substances upon the 
mucous membrane of the stomach or duodenum. Thus it was long ago 
noticed that injection of ether into the stomach will cause a flow of 
pancreatic juice, the juice having characters corresponding to the par- 
ticular stage of digestion in which the flow is brought about. More 
recently, other substances have been found to similarly affect the secre- 
tion. If mineral acid, or even organic acids such as acetic and lactic, 
be brought into contact with the duodenal mucous membrane, a secre- 
tion will result. Since alkaline substances have not the same effect, 
Dolinski? considers that the acid products of gastric digestion bring 
about their own neutralisation by inducing a flow of alkaline pancreatic 
juice when they enter the small intestine. Dolinski also found that 
fat excited reflexly a pancreatic secretion, and that alcohol was also 
effective in this direction, but only to a moderate degree. Gottlieb° 
agrees that reflexly induced secretion starts generally by stimulation of 
the duodenal mucous membrane. Becker‘ studied the effect upon the 
secretion of the introduction into the stomach of distilled water and 
of various salts. The salts employed were various alkaline salts, 
Carlsbad salts, sodium chloride, and “ Essentouck” mineral water. 
Becker found that distilled water exalted the secretion, whilst salts, 
especially alkaline salts, diminished it, both in amount and in proteo- 
lytic power. Sodium chloride in smaller doses was indifferent, in 
larger doses it behaved as the alkaline salts. The better the 
absorption the more marked the secretion. Water containing car- 
bonic acid is more easily absorbed than simple distilled water, and, 
correspondingly, the former excites a more plentiful secretion than the 
latter. 

We see, then, that the ordinary progress of the food can account for 
the secretion normally appearing; further, that the acid contents of the 
stomach, when passed into the duodenum, may cause a powerful secretion, 
and that alkaline salts in the stomach diminish the secretion. 

The ferments of the pancreatic juice and their antecedents.— 
Extracts made from the pancreas of many animals, and the pancreatic 
juice obtained by the establishment of fistula, possess the power of 
changing different foodstuffs. Heidenhain® showed in 1875 that there 
could be obtained from the pancreas a substance from which the proteo- 
lytic ferment could be derived, but which did not actually possess 
proteolytic activity. This substance he called “zymogen,” but since we 
are acquainted with substances having similar relations to other enzymes, 
it is better to retain the name zymogen for the whole class, and to refer 
each individual precursor by a name associated with the particular 
ferment. We thus speak of the particular zymogen of the proteolytic 
enzyme of the pancreas as trypsinogen. , 

1 Kiihne, ‘‘ Lehrbuch der physiol. Chem.” 2 Op. cit. 3 Op. cit. 


4 Arch. de sc. biol., St. Pétersbourg, 1893, vol. ii. 
5 Arch. f. d. ges. Physiol., Bonn, 1875, Bd. x. 


552 MECHANISM OF SECRETION OF PANCREATIC JUICE. 


Heidenhain established definite characters distinguishing trypsinogen 
from the actual enzyme, and showed that in some respects their behaviour 
was similar. The chief relations of the zymogen to the ferment are as 
follows :— 

1. Trypsinogen is soluble in glycerin. Some glycerin extracts of 
pancreas have no ferment activity, since the ferment is in the condition 
of zymogen, but if such glycerin extracts, dissolved in 1 per cent. 
sodium hydrate, be diluted with distilled but not boiled water (this 
being largely devoid of dissolved air), especially if digested for a time 
at 40° C., it will become active. 

2. If an inactive glycerin extract of fresh pancreas be dissolved in 
sodium carbonate, 1 to 2 per cent., the passing through it of oxygen 
will cause the same to become active. 

3. Platinum black will, according to Podolinski,’ also render the 
inert extract proteolytic. 

4. The converse of the change brought about by the influence of 
oxygen may also occur, for, through the deprivation of oxygen, activity 
ee lost. 

If fresh pancreas be mixed with the same weight of 1 per cent. 
wet acid for ten minutes, and then placed in glycerin, a very active 
extract will be obtained. The acetic acid converts the trypsinogen into 
trypsin. According to Kiihne,? trypsin is also formed from the zymogen 
by warming with alcohol. 

The amount of trypsin that can be obtained from an extract varies 
with the histological condition of the gland. When the luminal zone 
is of considerable width, a greater amount of proteolytic activity is 
shown than when it is much reduced. We are justified in associating 
the ferment with the granules seen in the cells. 

Sodium carbonate may be regarded as an adjuvant to the action of 
trypsin. Kiihne® showed that it worked best in solutions of the strength 
of 1 per cent. Edkins+ proved that sodium chloride has a beneficial 
influence on the digestion of fibrin by pancreatic extracts, and it may be 
noted that a large amount of the sodium carbonate associated with the 
pancreatic secretion must be converted into sodium chloride in the 
duodenum. Ewald® states that digestion of fibrin at the instance of 
trypsin can proceed in the presence ‘of 0°3 3 per cent. of hydrochloric acid, 
but, on the other hand, the prolonged action of dilute acids has been 
shown by Langley ° to be destructive of trypsin. If a glycerin extract 
of pancreas be warmed for two and a half hours in 0-05 per cent. hydro- 
chlorie acid, its proteolytic powers are appreciably curtailed. The 
diastatic ferment has not had the same study bestowed upon it as the 
proteolytic. It contrasts with this latter in that there is no further 
enhancement of its activity by treatment with such reagents as convert 
trypsinogen into trypsin. Liversedge? made observations in 1874, 
which suggested the existence of a diastatic zymogen, but the possi- 
bility of micro-organic change influencing his experiments was, as 
pointed out by Gamgee, 8 not eliminated. Accor ding to his observations, 


1 Breslau, 1876. 

2 Verhandl. d. naturh.-med. Ver. zu Heidelberg, 1876, N. F., Bd. i. 

S76id.. Bdsn 4 Journ. Physiol., Cambridge and London, 1891 Bd. xii. 
> Ztschr. f. klin. Med., Berlin, Bd. i. 

& Journ. Physiol., Cambridge and London, vol. iii. 

Journ. of Anat. and Physiol., London, 1874, vol. viii. 

‘‘ Physiological Chemistry,” vol. ii. p. 207. 


o 7 


VARIATIONS IN PANCREATIC JUICE. 553 


the zymogen is not soluble in water, thus contrasting markedly with 


other zymogens. 


We must regard the existence of a precursor in 


this case as doubtful, though it is undeniably possible that in the 


living cell an ante- 
eedent state of the 


to storage of the fer- 
ment; in that case the 
mere destruction of the 
cell might involve the 
breaking down of this 
hypothetical zymogen, 
on account of the pre- 
cursor of the diastatic 
ferment being less 
stable than that of the 
proteolytic. 

There is also no 
evidence of any zymo- 
gen of the fat-decom- 
posing ferment, pialyn. 

Finally, it has been 


fei ee 
ferment exists,adapted ,5 Bich ee ee 
(el ole ae 
a a) 


aie Ana 
inet, Ss ea aS 


tee | 
1 Fn 8 en 2 
br liye 


He eee Se Cunte OG We ONT S SEMFALSS OEE OAG 


Fic. 46.—Chart of the course of secretion of pancreatic juice. 
The abscisse correspond to hours; the ordinates corre- 
spond to c.c. of juice.—After Heidenhain. 


found that extracts of pancreas and the pancreatic juice itself! have 
the power of inducing a clot in milk, probably by the agency of some 
specific enzyme in the juice. 

The variations in the composition and amount of pancreatic 
juice during digestion.—From the earlier experiments of Bern- 


i 


Sno G1 Or Gy Ot 


epee ee ee a 
PAPC rr EP iE | 


Q 


~ AO Oa J AO 


hin 2 BF eG CFI Oi GAOT MR IGAASS AG SLAB LF 


Fie. 47.—Chart of the percentage composition of the flow of 
The abscisse correspond to hours ; the 
ordinates to percentage of solids. —After Heidenhain. 


pancreatic juice. 


eighteenth and twentieth. 


the quantity. 


stein,? and those of 
Heidenhain,? it ap- 
pears that the flow 
of pancreatic juice 
has somewhat the 
following course :— 

Before a meal 
is over there com- 
mences a secretion, 
which reaches a 
maximum not later 
than the third hour. 
Then the secretion 
sinks to about the 
sixth or seventh 
hour, and yet again 
increases to the 
ninth or eleventh ; 
thence it sinks gra- 
dually to about the 


The quality of the juice varies inversely as 
When one rises the other falls. 


The accompanying 


diagrams (Figs. 46 and 47) illustrate these variations. 


1 Halliburton and Brodie, Journ. Physiol., Cambridge and London, 1896, vol. xx. 


2 Op. cit. 


° Hermann’s ‘‘ Handbuch,” Bd. vy. 


554 MECHANISM OF SECRETION OF INTESTINAL JUICE. 


It has been pointed out by Mette that during normal digestion there is a 
certain independence between the secretion of ferment and the secretion of water. 
Observations have also been made by Wassilieff! on the influence of food in 
causing changes in the activity of the juice. He found that the maximum of 
secretion was in the first two hours, with meat diet in the first hour, and 
milk diet in the second hour. By changing the diet from meat to bread and 
milk, the proteolytic action of the juice diminished, whilst the diastatic action 
remained unaltered. On the other hand, when changing from bread and 
milk to meat, these were reversed. It is therefore to be noted that the 
relative quantity of both ferments is variable and dependent upon the food. 
The effects produced by other substances upon the flow of pancreatic juice 
have already been mentioned (p. 551). 


THe MECHANISM OF SECRETION OF Succus ENTERICUS. 


The histological evidence of secretion in the intestine.—The 
evidence of secretion from the histological standpoint is, in the case of 
the mucous membrane of the intestine, very incomplete. Paneth? pointed 
out that the cells at the base of the crypts of Lieberkihn frequently 
contain definite granules. These cells were also studied by Nicolas, 
who noticed different phases in the condition of the cells; thus, after 
secretory activity, he found them either free from or containing but 
few granules. 

Hardy and Wesbrook + found that in fasting animals the granules 
were large and numerous, in well-fed animals comparatively few, and 
smaller than in the fasting state. 

Bizzozero® regards the granules as mucigen granules. Schaffer © 
has also called attention to the fact that the cells containing them 
are goblet-shaped. From the manner in which they stain, their 
shape, and the fact that they are scattered in the crypt of Lieberkihn, 
it seems probable that they are to be looked upon as mucus-secreting 
cells. 

The cells covering the villi have been described by Nicolas’ as con- 
taining granules which do not stain, or at the best very shghtly, with 
safranin (unlike those just referred to). He states, however, that these 
granules give rise to some secretion. Examined in the fresh state, 
the cells do not show the existence of typical secretory granules. 

Brunner’s glands, from their structure, suggest the formation of 
a mucous secretion,’ but it has been stated by Krolow® that an extract 
of the glands will digest fibrin in acid solution, and they bear 
considerable resemblance, histologically, to the pyloric glands of the 
stomach. 

The experimental evidence of secretion of succus entericus.— 
Two methods have been adopted for obtaining evidence as to the 
nature of succus entericus. The first consists in isolating, by operation, 
a piece of the intestine, and observing the nature of the liquid which 


1 Arch. de sc. biol., St. Pétersbourg, 1893, vol. ii. 

2 Arch. f. mikr. Anat., Bonn, 1888, Bd. xxxi. 

3 Internat. Monatschr. f. Anat. u. Physiol., Leipzig, 1891, Bd. viii. 

+ Journ. Physiol., Cambridge and London, 1895, vol. xviii. 

Anat. Anz., Jena, 1888, Bd. iii.; Atti d. r. Acad. d. sc. di Torino, 1888-9. 

} Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1891, Abth. 3, Bd. ce. 

TOnrcrt. 

8 Kuezynski, Internat. Monatschr. f. Anat. u. Physiol., Leipzig, 1890, Bd. vii. 
9 Berl. klin. Wehnschr., 1870, No. 1. 


o Uw 


EXPERIMENTAL EVIDENCE. 555 


collects in the interior; the second, in making extracts of the intestinal 
mucous membrane and investigating the digestive properties of such an 
extract. 

A method of permanently isolating a portion of the intestine was 
first devised by Thiry.t The abdomen “of an animal having been opened, 
a piece of intestine was cut away from its continuity with “the main gut 
without dividing the mesentery. The two ends of the main gut were 
then brought together and ligatured, so that union of the cut surfaces was 
brought Bia the continuity of the intestine being thus re-established. 
The isolated portion of the gut was then closed by a ligature at its lower 
end, while the upper end was sewn into the incision in the abdominal 
wall, a blind sac being thus formed. Vella? modified this procedure by 
inserting the lower end of the isolated gut also into the abdominal wall ; 
thus affording two openings for the separated intestine. This operation, 
performed with due antiseptic precautions, is of constant service at the 
present day, and is generally described as the establishment of a 
“Thiry-Vella ” fistula. 

Older observers, such as Bidder and Schmidt,’ had, ligatured off from 
the general tract short lengths of the intestine, and, after replacing them 
in the abdominal cavity for some hours, had examined the accumulated 
liquid. 

The chief facts that have been brought to light by these methods 
are as follows:—In the absence of any stimulus, little or no secretion 
has been obtained, as a rule. Thiry,t with mechanical or electrical 
stimulation, obtained a thin yellowish ‘alkaline secretion, albuminous in 
character. After food had been taken, although no previous secretion 
was manifest, some fluid began to form. According to Rohmann,° the 
introduction of starch, sugar, or peptone provokes intestinal secretion. 
The administration of pilocarpime results, according to Masloff® in 
secretion. Gamegee,’ however, found that it was possible to produce 
considerable increase of other secretions by the administration of 
pilocarpine without affecting the succus entericus to any extent. This 
result he attributed to the fact that probably different regions of the 
intestine reacted with different vigour to pilocarpine, the lower portion 
of the intestine secreting a greater quantity than the upper.’ 

With respect to the existence of nervous influences on the secretion, 
Thiry found no result to come about from stimulation of the vagi. 
Budge ® and Lamansky ! obtained increase of secretion after extirpation 
of the ccehac and mesenteric plexuses, but Adrian! did not succeed in 
obtaining this increase. Brunton and Pye-Smith ” found, in confirmation 
of an observation of Moreau, that if all nervous connections be severed 


1 «Wine neue Methode den Diinndarm zu isolieren,” Sitzungsb. d. k. Akad. d. Wissensch., 
Wien, 1864, Bd. i. 

2 Untersuch. z. Naturl. d. Mensch. u. d. Thiere, 1881, Bd. xiii. 

3 “Die Verdauungssifte und der Stoffwechsel,” Leipzig, 1852. 4 Op. cit. 

> Arch. f. d. ges. Physiol., Bonn, 1887, Bd. ii. 

® Untersuch. a. d. physiol. Inst. d. Univ. Heidelberg, 1882, Bd. ii. 

7 «* Physiological Chemistry,” London, 1893, vol. ii. 

® That pilocarpine pr ovokes an intense secretory charge in the crypts of Lieberkiihn of the 
large intestine, is manifest from the experiments of Heidenhain (Hermann’s ‘‘ Handbuch,” 
Bd. v.). 

9 Verhandl. d. k. k. Leopold-Carol. Acad. d. Naturforscher., 1860, Bd. xix. 

10 Ztschr. f. rat. Med., 1866. 

U Beitr. z. Anat. u. Physiol. (Eckhard), Giessen, 1863, Bd. iii. 

Rep. Brit. Ass. Adv. Sc., London, 1874, 1875, 1876. 

18 Compt. rend. Acad. d. sc., Paris, 1863, Bd. lxvi. 


556 MECHANISM OF SECRETION OF INTESTINAE JUICE. 


between higher centres and the mucous membrane by dividing the 
intestinal nerves, an accumulation of fluid takes place. Brunton and 
Pye-Smith also found that if the inferior ganglia of the solar plexus and 
their continuation along the superior mesenteric artery are left in con- 
nection with the cut, this accumulation does not take place. 

L. Hermann ! initiated a somewhat different method of investigating 
the secretion. A loop of intestine was separated from the main gut, and 
its ends joined so as to form a confluent ring. This was replaced in the 
intestine, and its contents examined after some weeks. These contents 
were found to consist of solid material, and it was presumed that this 
represented the inspissated juice. Blitstein and Ehrenthal? continued 
these experiments, and came to the conclusion that the solid mass found 
had its origin in two sources; the first being the intestinal fluid, and the 
second detached intestinal epithelial cells. They noticed micro-organisms 
also to be present. Fr. Voit,? who simply sewed up the ends of an iso- 
lated loop, found, after the lapse of three weeks, a yellowish-grey mass, in 
which he recognised no epithelium, and which he regarded as simply 
inspissated juice. The nature of the fluid excreted in the Thiry-Vella 
loop has been frequently examined. It is of a yellowish colour, and 
contains albumin, and also a rather large amount of sodium carbonate. 
It possesses certain ferment-powers, though with regard to these there 
is considerable divergence of statement. Thiry* found it to dissolve 
fibrin, but not to affect other proteids. Masloff® found it to act feebly 
on starch, but not on proteids. 

Funke ® stated that starch injected into isolated loops is not con- 
verted into sugar. Later observers,’ experimenting by the above 
methods, agree that starch is converted into sugar, and Robman’s 
experiments suggest a greater diastatic activity in the upper part of the 
intestine than the lower. This observer also finds, as Paschutin® had 
previously pointed out from experiments with extracts, that the 
intestinal juice has the power of inverting cane-sugar. It is to be noted 
that this is, even markedly, the case, as Gamgee® points out, in animals 
which would have no opportunity, from the nature of their food, of 
utilising the enzyme causing such a change. Observations made recently 
by Pregl?° ona Thiry-Vella fistula established in a lamb, have somewhat 
completed the knowledge that has accrued from this method of research. 
He found that the secretion was continuous, but it increased the first hour 
after food, and this went on to about the third hour. From a length of 
intestine of 72 cm. he obtained about 5 germs. of intestinal juice per hour; 
this rate of secretion diminished to the fifth hour, when it reached 3 grms. 
per hour, and remained at this rate for many hours after. He refers to 
the prolapse which occurs at first, and with which other observers have 
found difficulty, and points out that this is evidence of a catarrhal condi- 
tion, which itself would account for a certain amount of flow, although he 
failed to notice any difference between the juice reinforced by catarrhal 


1 Arch. f. d. ges. Physiol., Bonn, 1889, Bd. xlvi. 

2 Tbid., 1891, Bd. xlviii. * Ztschr. f. Biol., Miinchen, 1893, Bd, xxix. 

4 Op, cit. 5 Op. cit. 6 *¢Tehrbuch.” 

7 Gumilewski, Arch. f. d. ges. Physiol., Bonn, 1886, Bd. xxxix. ; Rohmann, op. cit. ; 
Dobroslawin, ‘‘ Beitr. z. Physiol. d. Darmsiiftes,” Untersuch. a. d. Inst. f. Physiol. u. 
Histol. in Graz, Leipzig, 1870; Lannois et Lépine, Arch. de pliystol. norm. et path, 
Paris, 1883. 

8 Arch. f. Anat. uw. Physiol., Leipzig, 1871. 9 Op. cit. 

0 Arch. f. d. ges. Physiol., Bonn, 1896, Bd. 1xi, 


EXPERIMENTAL EVIDENCE. 554 


exudation and the simple juice. Pilocarpine, he found, did not cause 
increased secretion, nor did electrical stimulation. He describes the 
juice as consisting of a yellow fluid, in which are suspended flocculi, 
staining deeply with eosin, and mainly mucous in nature. The alkalinity 
is marked. Albumin and globulin are present, and what he regarded as 
probably albumose. He also found a small amount of urea. The secre- 
tion had no action upon proteids. From starch paste was formed after 
twenty-four hours a fermentable sugar. This action was shown more 
powerfully in the earlier than the later months after the operation. 
Raw starch was not affected. He found that dextrose (not maltose) was 
formed both from starch and glycogen. No fat-splitting action was 
manifest, but the juice easily emulsified fat. The loop experimented 
upon was found to be situated about three times as far from the stomach 
as from the large intestine. Pregl calculates that the whole intestine 
would secrete nearly 3 litres in twenty-four hours. 


It is difficult to say to what extent we are justified, from experiments 
performed on isolated loops, in forming conclusions regarding the nature of 
normal succus entericus. The first question that suggests itself is, How far 
is the fluid secreted a catarrhal production? As above stated, Pregl has 
pointed out that the mere prolapse of the gut causes a catarrhal increase above 
what he regards as the ordinary flow. The facility with which micro-organisms 
could enter would tend to increase any pathological condition. The presence 
of albumose in a fluid which does not digest proteid, and also of urea, suggests 
a pathological condition. Many of the ferment powers attributed to the 
juice might be due simply to desquamated epithelium from the walls of 
the loop. : 

Klecki! has criticised in the same way the experiments of L. Hermann, 
Blitstein and Ehrenthal, and Voit, dwelling on the abnormal conditions of the 
loop, and the small number of experiments upon which their conclusions are 
based. He himself finds that when few micro-organisms are allowed to remain 
in the gut, much less solid substance is finally found, and states that a large 
amount of contents is found in Hermann’s rings only when the intestinal wall 
shows pathological changes, or if complete disinfection of the loop has not 
been carried out. 

It would seem, therefore, that we must hesitate before accepting all the 
conclusions that have been drawn from the employment of the methods of 
isolated loops and Thiry-Vella fistula, bearing in mind that the juice so 
obtained is probably seldom entirely uninfluenced by the abnormal condition 
induced by the operation. Many, however, regard it as probable that the 
erypts of Lieberkiihn, through their lining epithelium, yield a secretion 
which is of assistance in dissolving the products of digestion by other juices, 
even if it has no very well-marked digestive properties itself. 


We may finally proceed to consider how far extracts made from 
the intestinal wall are characterised by the possession of specific 
properties. 

In the first place, we must bear in mind that the intestinal mucous 
membrane has primarily, without doubt, an absorbing function. We 
have also reason to believe that the digested food in its passage through 
the epithelial cells may undergo considerable changes. Consequently, on 
making extracts of these epithelial cells, we may be separating substances 
which are never secreted into the lumen of the intestine, but which 
merely exercise influence on the absorbed food as it passes through the 

1 Wien. klin. Wehnsehr., 1894, Bd. vii. 


558 MECHANISM OF SECRETION OF INTESTINAL JUICE. 


cells. It is, therefore, not justifiable to assume that the secreted 
juice has the same action as an extract of the intestinal mucous 
membrane. 

That extracts of the intestinal mucous membrane have marked 
physiological properties, there is little doubt. It is comparatively easy 
to make such extracts free from micro-organisms, and it is generally 
agreed that these extracts have a considerable power of inverting cane- 
sugar and of changing starch, in an intense degree, into dextrose, 
probably through the stage of maltose. 


MECHANISM OF BILE SECRETION. 


By D. Nok Parton. 


Contents.—Mode of Formation of Bile Constituents, p. 559—Water, p. 559— 
Inorganic Salts, p. 560—Nucleo-Proteid, p. 561—Bile Acids, p. 562—Bile Pig- 
ments, p. 563—Cholesterin, p. 564—Lecithin, ete., p. 564—Influence of various 
Factors on the Secretion of Bile, p. 564—Flow of Blood, p. 565—Food, p. 565 
—Pressure ot other Organs, p. 567—Nerves, p. 567—Chemical Substances, p. 
567—General Conclusions, p. 569. 


In considering the mechanism of bile secretion, it must be remembered 
that the formation of bile is only one of many functions performed by 
the liver. 

Placed as it is upon the course of the portal vein, the great channel 
of absorption of material from the alimentary canal, the liver regulates 
the supply of carbohydrates to the body by storing the surplus sugar 
absorbed in the form of glycogen. It also gets rid of any excess of 
nitrogen absorbed, by converting it into the innocuous and easily 
eliminated urea. In addition to performing these functions, the liver 
acts as one of the great storehouses of iron in the body, and in many 
animals it is also a situation in which surplus fats are accumulated. 

When these numerous functions are considered, the small amount of 
bile formed per diem by so large an organ is the less surprising. In man 
about 800 or 900 germs. of bile, with about 14 or 15 grins. of solids, are 
daily secreted from the liver, an organ which weighs about 1600 grms. 

In studying how bile is formed in the liver, it is necessary to 
remember that, besides the great mass of liver cells, there are in- 
numerable bile passages lined by a living epithelium. In most animals 
a saccular diverticulum, the gall bladder, is developed upon these 
passages. In this and in the passages the surplus bile accumulates. 
How far the liver cells, and how far the cells lining the ducts, act in 
producing the various constituents of bile, must be subsequently con- 
sidered. 

The bile is a fluid containing many different substances in solution 
(see article, “ Chemistry of Bile” ), and an investigation of the mechanism 
of bile secretion necessitates a consideration of the mode of production 
of each of these. 


Mope oF FORMATION OF BILE CONSTITUENTS. 


Water.—The water of the bile is in part secreted from the walls 
of the bile passages, for it has been found that when the cystic duct 
is occluded, and the fundus of the gall bladder opened, a small amount 


560 MECHANISM OF BILE SECRETION. 


of fluid, about 70 c.c. per diem, is continually secreted from the walls of 
the gall bladder! How far this fluid is a physiological secretion, and 
how far it is due to pathological conditions, is difficult to decide. 

That water is secreted by the liver cells, as well as_ by the cells of 
the ducts, is proved by the way in which pigments,? which are secreted 
by the liver cells alone, are washed down into the bile passages. 

The elimination of the water of the bile is a process of secretion, 
and not of transudation. Heidenhain’s observations on the relative 
pressures in the bile passages and in the blood vessels passing to the 
liver,? given in the following table, demonstrate very clearly that, though 
the pressure of secretion of bile is low, it is nevertheless considerably 
higher than the blood pressure in the portal vein. 


Nol BileiProssures Pressure poem te 

1 220 mm. carbonate of soda sol. 90 mm. carbonate of soda sol. 
2 175 ,, i 1 G7 RS » 

3 204 75, a 210) = 5. ap 

4 110° *. . 50 vcs . 

5 180 ,, . ie Gone - 


The absorption of water from the alimentary canal seems under 
certain conditions to increase the secretion of water by the liver. 

Rohrig,t Bidder and Schmidt,? and Zalesky,® noticed that the intro- 
duction of water into the stomach and intestine of dogs with bilary 
fistulee increased the flow of bile. Rosenberg’ found that if the intestine 
had previously been cleared out by a glycerin enema, the introduction 
of 500 e.c. of water into the intestine increased the flow of bile. In a 
case of complete biliary fistula in a woman,’ the amount of the bile 
secretion was greater upon the days on which a large quantity of fluid 
was taken, and this increase was in the water of the bile, not in the 
solids. 

Inorganic salts.—The analyses of the bile of the dog given by 
Hoppe-Seyler,® show that in bile taken from the gall bladder the salts 
constitute about 5 per cent. of the solids, while in freshly secreted bile 
they amount to about 15 or 14 per cent. The freshly secreted bile 
alone need be considered in discussing the mode of formation of these 
salts. A comparison of the salts of the bile with the salts of the blood 
plasma indicates that the percentage amount of salts is smaller in bile 
than in blood, and that, while chloride of sodium is the most abundant in 


1 Birch and Spong, Jowrn. Physiol., Cambridge and London, vol. viii. p. 378 ; Mayo 
Robson, Proc. Roy. Soc. London, 1890, vol. xlvii. p. 499. 

2 Wertheimer, Arch. de physiol. norm. et path., Paris, 1891, p. 724. 

3 Hermann’s ‘‘ Handbuch,” Bd. v. S. 269. 

4 Med. Jahrb., Wien, 1873, Bd. ii. 

> «Die Verdauungssifte,”’ 1852, S. 166. 

6 Hofmann and Schwalbe, Jahresb. ii. d. Fortschr. d. Anat. u. Physiol., Leipzig, 1877, 
S. 219. 

7 Arch. f. d. ges. Phystol., Bonn, 1890, Bd. xlvi. S. 361. 

8 Noél Paton and Balfour, Rep. Lab. Roy. Coll. Phys., Edin., 1891, vol. iii. p. 191. 

® «*Physiol. Chem.,” 8. 302. 


FORMATION OF BILE CONSTITUENTS. 561 


both, in bile the proportion of this salt is not nearly so high as in 
plasma. This may possibly be explained by the withdrawal of hydro- 
chloric acid in the stomach, leaving the soda to be combined with the 
organic acids of the bile. 

A study of the excretion of chlorine in the bile has been made by 
Dagnini in Albertoni’s laboratory... He finds that in dogs with a 
permanent fistula the percentage of chlorine varies little, and that it 
is only slightly raised by the administration of chloride of sodium, or 
of potassium. Chlorides, as is well known, are chiefly excreted by 
the kidney. 

Giovanni Pirri” has studied the secretion of sodium and potassium, 
and finds that, while the amount of sodium excreted per diem is very 
constant in spite of variations in diet, and in spite of the administration 
of chloride of sodium, the excretion of potassium varies within wide 
limits, and is increased by giving sodium and potassium chloride in the 
food. The sodium is in great measure combined with the organic 
acids of the bile, and hence these results do not throw light upon the 
excretion of sodium in inorganic compounds. 

On the secretion of lime salts, work has been done under Naunyn’s 
direction by Jankau. He shows that the amount of lime in bile is very 
small, and that it is not increased by the administration of lime salts. 
From the fact that lime salts are present in the secretions from mucous 
membranes, Naunyn suggests that the lime of the bile may be formed in 
the bile passages. 

The very small quantity of iron which exists in the bile (less than 
1 mgr. per diem in the dog)* may be derived from the iron stored in the 
liver cells, or may be formed from the disintegration of the epithelial 
lining of the passages. Evidence on the subject is wanting. 

How far the other inorganic salts are secreted by the liver cells, 
and how far by the cells lining the bile passages, cannot be considered 
as established. There is clear evidence to show that they are, in part 
at any rate, formed in the latter situation. In a series of analyses of 
bile, collected from a woman with a complete biliary fistula, it was found 
that during attacks of fever the true biliary constituents, the organic 
salts and pigments, were markedly diminished, while the proportion of 
Inorganic salts remained unaltered, between 0-7 and 0°8 per cent.® 

Birch and Spong’s analysis of the fluid from the gall bladder showed 
the presence of 0:826 per cent. of inorganic salts, of which the chief was 
chloride of sodium. Mayo Robson found 0°84 per cent. of inorganic 
matter. Analysis of freshly secreted human bile gives about the same 
proportion of salts. Hence, since the amount of salts is the same in 
the small amount of fluid secreted from the bile passages, and in the 
total amount of bile poured out from bile passages and liver cells 
together, about the same proportion of salts must exist in the secretion 
from each. 

Nucleo-proteid.—The mucus-lke nucleo-proteid of bile is formed in 
the bile passages and gall bladder. The amount in bile is small, about 
0-2 per cent. 

1 Mem. r. Accad. d. sc. d. Ist. di Bologna, 1893, Ser. 5, vol. i. p.°3. 

2 Tbid., 1893. 

3 Naunyn, ‘‘Cholelithiasis,” translated by A. E. Garrod, New. Syd. Soc., p. 15. 

* Anselm, Arb. d. pharmakol. Inst. zw Dorpat, Stuttgart, 1892, Bd. vii. 


° Rep. Lab. Roy. Coll. Phys., Edin., vol. iv. p. 44. 
§ Hoppe-Seyler, ‘‘ Physiol. Chem.,” S. 302. 


VOL. 1.—36 


562 MECHANISM OF BILE SECRETION. 


In cases of occluded gall bladder this mucin-like substance has been 
found to be the chief organic solid of the secretion.t 


Mayo Robson's Analysis. 


Organic matter, chiefly mucin. : : 672 per cent. 
Chlorides equal to NaCl. 4 : 3 ii ee 
Sodium carbonate , 3 : 0 bees 
Other salts containing ‘Phosphates potassium 

salts, ete. , ‘ : ‘071 


33 

The fact that the amount of his substance does not vary with the 
true bile constituents either at different periods of the day,? or in febrile 
conditions,? indicates very clearly that it is not formed by the liver 
cells. 

Salts of the bile acids.—These are entirely produced in the liver 
cells. In Birch and Spong’s case, and in the case examined by Mayo 
Robson, they were entirely absent from the secretion of the gall 
bladder. 

That they are actually formed by the liver cells, and not merely ex- 
tracted from the blood, was demonstrated by Minkowski and Naunyn.* 
These observers found that, while bile salts are normally absent from the 
blood, they appear when the bile duct is ligatured. If, however, the 
liver be excluded from the circulation, there is no accumulation of bile 
salts in the blood. 

The source of the cholalic acid moiety of the glycocholic and 
taurocholic acids is unknown. The source of the glycine and taurine is 
to be sought ultimately in the proteids of the body and of the food, 
since these alone can yield the nitrogen and sulphur. Both are amido- 
acids of the fatty acid series. 

Nencki, Pawlow and Zaleski? have shown that the surplus proteid 
of the diet is largely broken down into ammonia compounds in the wall 
of the intestine, and these compounds pass to the liver. Von Schroder ® 
demonstrated that ammonia compounds are readily converted to urea by 
the liver. Hence by far the greater quantity of nitrogen in excess of 
that required must undergo this transformation, and it is not to be 
expected that an additional quantity of proteids in the food will lead to 
a markedly increased formation of bile acids. Spiro,’ by feeding animals 
with biliary fistulee upon various kinds of food, found that a proteid diet 
increased the nitrogen and sulphur excreted in the bile, but not in 
proportion to the amount of proteid taken. 

The following figures illustrate Spiro’s results :— 


Sulphur of Bile | Nitrogen of Bile 
Food. bs 5 Grms. | in Grins. 
Fasting , ‘ : : *059 195 
125 grms. flesh . , : 089 "292 
500 bs Xp ue "155 “398 
949 - sone tel 173 | 604 


1 Hoppe-Seyler, ‘‘ Physiol. Chem.,” S. 302. 

2 Rep. Lab. Roy. Coll. Phys., Edinburgh, vol. ili. p. 204. 

3 Thid. p. 212. 4 Arch. jf. exper. Path. 1. Pharmakol., Leipzig, Bd. xxi. S. 7. 
5 Ibid., Bd. xxxvi. S. 26. 

6 Ztschr. f. physiol. Chem., Strassburg, Bd. ii. S. 234. 

7 Arch. f. Physiol., Leipzig, 1880, Supp. Bd. 8. 50. 


BILE ACIDS AND PIGMENTS. 563 


Kunkel, from similar experiments on dogs, concluded that a definite 
part of the sulphur taken in the diet is excreted in the bile, but the 
increase in biliary sulphur occurs two or three days after the ingestion, 
and not upon the same day, as is the case with the sulphur of the urine. 
Of the sulphur of the food, from 8 to 30 per cent. is excreted in taurine. 

In man on an ordinary diet, about 33 grms. of urea with 15 grms. of 
nitrogen are daily formed, while only about 10 grms. of bile acids with 
about 0°3 grms. of nitrogen are excreted. The increased ingestion of 
proteids leads to a proportionate increased excretion of urea, and any 
increase in the bile acids is necessarily so small that it may readily 
be overlooked. Similarly, any increased decomposition of the proteids 
of the tissues leads to a proportionately increased excretion of the 
nitrogen in the form of urea, and any increase in the bile acids which 
may occur must be very trifling. 

Whether the bile acids which are absorbed from the intestine can 
be again excreted by the liver cells, has been investigated by injecting 
into the blood of animals a bile salt differing from that which is normally 
present. In dogs the taurocholate of soda is the normal salt of the 
bile. After injecting glycocholate of soda, Prévost and Binet, and 
Weiss*® found it in the dog’s bile. Socoloff on the other hand, failed 
to detect it after it had been injected. Huppert® observed that the 
injection of glycocholic acid increases the amount of bile acids in the 
bile. The experiments of Rosenberg® show that the administration of 
bile salts causes an increased secretion of bile with a marked increase 
in the solids. They appear to be the only substances which produce 
this result, and since the bile salts are the most abundant solids of bile, 
it seems fairly certain that they are absorbed, and re-excreted from the 
blood by the liver. 

Bile pigments.—The pigments must be produced in the liver cells, 
since the secretion from the bile passages is entirely destitute of colour- 
ing matter.’ They are formed from the hematin moiety of the hemo- 
globin molecule. The injection of free hemoglobin into the blood,’ or 
the setting free of hemoglobin by solution of the red corpuscles,? rapidly 
leads to a great increase of the bilirubin of the bile. Minkowski and 
Naunyn, by experiments upon birds,” have confirmed these observations. 
They further found that if the liver is excluded from the circulation 
the formation of bilirubin does not take place. They thus showed that 
bilirubin is actually produced in the liver cells. The iron-containing 
part of the hematin molecule appears to be split off and retained in 
these cells, giving rise to the accumulation of iron in the liver, which 
follows the disintegration of red corpuscles. 

Not only do the liver cells manufacture bilirubin, but when this or 
any other bile pigment is present in the blood they take it up and eliminate 


1 Arch. f. d. ges. Physiol., Bonn, Bd. xiv. 8. 344. 

2 Compt. rend. Acad. d. sc., Paris, 1888, tome cvi. p. 1690. 

3 Bull. Soc. imp. d. nat. de Moscou, 1884. 

4 Arch. f. d. ges. Physiol., Bonn, 1875, Bd. xi. S. 166. 

> Arch. d. Heilk., Leipzig, 1869, Bd. v. 

8 Arch. f. d. ges. Physiol., Bonn, 1890, Bd. xlvi. S. 334. 

7 Birch and Spong, Journ. Physiol., Cambridge and London, vol. viii. p. 378; Mayo 
Robson, Proc. Roy. Soc. London, 1890, vol. xlvii. p. 499. 

8 Stidelmann, Arch. f. exper. Path. u. Pharmakol., Leipzig, 1890, Bd. xvii. S. 93. 

® Afanassiew, Zischr. f. klin. Med., Berlin, Bd. vi. Heft 4. 

0 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1886, Bd, xxi. S. 1. 

1 Hunter, Lancet, London, 1892, p. 1262. 


564 MECHANISM OF BILE SECRETION. 


it. This was definitely proved by Wertheimer, who injected into the 
circulation of dogs the bile of the ox and sheep. The bile of these 
animals contains a pigment, cholohematin, which gives a characteristic 
spectrum, and the appearance of this spectrum in the bile of the dog 
showed that cholohematin had been taken up and excreted. 

Cholesterin.— Whether cholesterin is formed in the liver cells, or in 
the cells lining the bile passages, or in both, is not definitely known. 
In the two cases of fistula of the gall bladder already referred to, the 
presence or absence of cholesterin is not noted.? 

That the cholesterin is formed somewhere within the liver, and not 
merely excreted by it, is shown by an experiment by Jankau, performed 
in Naunyn’s laboratory.? He injected cholesterim into dogs, and also 
gave it in their food, and ascertained that it had been absorbed; but he 
failed to find any increase of cholesterin in the liver tissue, or in the 
bile. The analyses of the liver and bile made by Kausch * in the same 
laboratory show no relationship between the amount of cholesterin in 
the gland, and in its secretion. Thomas,? who also worked in Naunyn’s 
laboratory, found that there is no relationship between the amount of 
cholesterin excreted and the kind of food taken. When the dog under 
observation suffered from catarrh of the bilary passages, there was a 
marked increase in the cholesterin of the bile. 

From these experiments, and from the fact that cholesterin is always 
found where cells are disintegrating, Naunyn strongly supports the view 
that cholesterin is produced, not in the liver cells, but from the cells of 
the passages, and that it is a product of the disintegration of their 
protoplasm. 

Lecithin and other compounds of the fatty acids.—The occur- 
rence of these bodies in the secretion from the gall bladder has not 
been observed. On the other hand, lecithin and fat are constant and 
abundant constituents of liver cells. Liver tissue contains about 2°35 
per cent. of lecithin, and about 3 or 4 per cent. of fat.2 Thomas found ® 
that, while cholesterin was unaltered in amount by the administration 
of various diets, the amount of fat in the bile depended largely upon 
the amount of fat taken in the food; and since the fats of the food are 
frequently stored in the liver cells, it is probable that the fatty acid 
compounds in the bile are derived from this source. 


INFLUENCE OF VARIOUS FACTORS UPON THE SECRETION. 


The investigation of the influence of varying conditions upon bile 
secretion is a matter of extreme difficulty, for the bile may accumulate 
in the gall bladder and passages to be expelled from the liver some time 
after secretion. 

The flow of bile is governed by— 

1. The rate of secretion. 

2. The activity of the muscular walls of the passages. 

3. The pressure upon the liver of adjacent organs. 


1 Arch. de physiol. norm. et path., Paris, 1891, p. 724. 
2 In the colourless fluid from a case of hydrops cystidis fellew, I found a considerable 
quantity of cholesterin. 
3 “*Cholelithiasis,” translated by A. E. Garrod, New Syd. Soc., 1896. 
4 Diss., Strassburg, 1891. 
® Noel Paton, Journ. Physiol., Cambridge and London, 1896, vol. xix. p. 213. 
Loc. cit, 


INFLUENCE OF VARIOUS FACTORS. 565 


Further, the liver being placed upon the efferent vessel of the 
alimentary canal, must have its vascular condition altered by every 
modification in that of the gastro-intestinal tract, and it is impossible to 
eliminate this element while studying the action of any agency on bile 
secretion. 

Influence of the hepatic circulation upon bile secretion.— 
The circulation in the liver may be profoundly altered without actual 
stoppage of bile secretion. Thus it has been shown, in cases where, by 
the method devised by Oré, the portal blood has been directed into the 
inferior vena cava, that bile is still secreted by the liver;! while 
Wertheimer? has confirmed the results of older investigators, that 
ligature of the hepatic artery does not immediately stop the secretion, 
although ultimately necrosis of liver tissue supervenes and leads to 
abolition of function. 

But while these marked disturbances do not at once stop secretion, 
there is evidence that its rate depends upon the vascular supply. 
Thus Heidenhain has shown® that in dogs, section of the splanchnic 
nerves, which causes a dilatation of the portal vessels, produces a 
marked increase in the flow of bile. If, however, this local dilatation 
is accompanied by a general dilatation, such as is produced by section of 
the spinal cord in the neck, a fall in the secretion occurs. Munk,‘ on 
the other hand, has shown that stimulation of the splanchnic nerves, 
which produces constriction of the vessels, leads to a diminution in 
the rate of bile secretion. 

How far this influence of alteration in the blood supply is due to 
variation in pressure, and how far to alteration in the rate of blood flow 
through the liver, has not been directly investigated. But the observa- 
tion of Rohrig,’ that constriction of the vena cava inferior, which raises 
the pressure in the liver while decreasing the rate of blood flow, 
diminishes bile secretion, seems to indicate that the rate of flow is of 
more importance than the mere intravascular pressure. In this con- 
nection the relationship of the pressure of secretion to blood pressure 
(p. 560) must be borne in mind. 

Effects of food.—Starvation, according to Bidder and Schmidt, 
causes a diminution in the amount of bile secretion, and a corresponding 
fall in the amount of solids. Their experiments are unsatisfactory, in 
so far that cats were taken at various stages of starvation up to 240 
hours’ after food, a temporary fistula made, and the bile secretion 
determined for a short period only. The most recent contribution 
to our knowledge of this subject was made by Lukjanow,’ who 
determined the changes in the various solids of the bile in guinea-pigs 
kept without food or water. He concludes that both the secretion of 
water and of solids diminishes throughout the period of fasting. 

From the investigations on the relationship of bile secretion to 
the flow of blood through the liver, it is obvious that the dilatation 
of the abdominal vessels, which occurs in digestion, will of itself 
cause an increased secretion of bile. Such an increased flow has 


1 Arch. d. sc. biol., St. Pétersbourg, 1892, vol. ii. 

* Arch. de physiol. norm. et path., Paris, 1892, p. 577. 

3 Hermann’s ‘‘ Handbuch,” Bd. v. S. 266. 

4 Arch. f. d. ges. Physiol., Bonn, 1874, Bd. viii. S. 151. 

> Med. Jahrb., Wien, 1873, Bd. ii. 

§ Bidder and Schmidt, ‘‘ Die Verdauungssafte.” 

7 Zischr. f. physiol. Chem., Strassburg, 1892, Bd. xvi. S. 87. 


566 MECHANISM OF BILE SECRETION. 


been observed by various investigators. The most careful observations 
on the influence of food in bile secretion are those recorded by Hoppe- 
Seyler! The experiments were made on a dog with a permanent 
biliary fistula, and they show that within an hour after food the flow of 
bile is slightly and temporarily increased. It is very probable that 
this initial increase is simply due to reflex stimulation of the gall bladder 
and bile passages, expelling the bile already secreted. Four or five 
hours after a meal the flow is enormously increased, the amount of 
bile solids rising with the amount of bile. The extent of this accelerated 
flow indicates that it is actually an increased secretion. How far it 
is due to the increased vascularity of the abdominal viscera, and 
how far to the stimulating action of absorbed material on the liver 
cells, is not made manifest by the experiments. About nine or ten 
hours after a meal there is a secondary 
increase, not so marked as the first, but 
lasting for two or three hours, and accom- 


BILE 
grams 
42 


nY oil, tel seal panied by a still more marked rise in the 
a ol piles excretion of solids. The cause of this is 
34 ft it | unknown. 

32 ee As to the special influence of the 
30 + - various constituents of the food, our know- 
28 aarii = ledge is somewhat defective. The re- 
26 ea 7 searches of Rosenberg? and of Barbera,* 


on dogs with a permanent fistula, show an 
increase in the secretion of bile and of the 
bile solids after proteid food. The latter 
observer states that carbohydrates have 
also a certain effect in increasing the secre- 
tion of bile, but that their effect is very 
small indeed. Both observers find that 
the administration of fats very markedly 
increases the bile flow ; but while in Rosen- 
berg’s experiments the flow of bile under 
the influence of fats was greater than with 
proteids, in Barbera’s the increase was most 


O 3 6 9 12 hours A 
Water ........ Carbohydrates mmarked on a diet of flesh. 


----fats ——.— Mixed Diet The accompanying chart (Fig. 48) gives 


Ta Oe a summary of Barbera’s observations. 


Fic. 48.—Showing influence of In another paper Barbera * shows that 
paras daa aialis upon the the exeretion of bile after a meal of pro 
teids or carbohydrates runs parallel aa 
the secretion of urea, but that after a meal of fats the bile secretion 
increases out of proportion to the urea. 

The shght increase in the secretion following the administration of 
carbohydrates is probably due to the vascular ‘dilatation. The more 
marked increase after fats may be related to their more prolonged 
digestion, and the correspondingly greater and more sustained dilatation 
of vessels. The increase after proteids is in part due to the same cause, 
but may also be due to the increased functional activity of the liver, 


1 “Physiol. Chem.,” S. 308. 

2 Arch. f. d. ges. Physiol., Bonn, 1890, Bd. xlvi. S. 2438. 
5 Bull. d. sc. med. di Bologna, 1894, Ser. 7, vol. v. 

+ “* Rapporto tra la eleminazione dell urea e della bile.” 


INFLUENCE OF VARIOUS FACTORS. 567 


which has to deal with nitrogen in excess of the requirements of the 
body. 

After every kind of food the absorption of bile salts and their action 
on the liver must be taken into account as a factor in increasing the 
flow of bile (see p. 565). 

Influence of .pressure of surrounding structures.—The liver, 
being situated just below the diaphragm and above the abdominal 
viscera, is subject to marked variations in pressure. It has already 
been pointed out that a considerable quantity of bile may collect in 
the bile passages. By pressure from adjacent organs, this may be 
squeezed out. The facts that section of one vagus reduces the bile flow 
only when the frequency of respiration is diminished,’ and that section 
of the vagus just above the diaphragm, which has no influence on the 
rate of respiration, leaves the bile secretion unaltered, and that stimula- 
tion has also no effect, seem to indicate that the flow of bile is acceler- 
ated by respiratory movements. 

The very marked rise in the amount of bile poured out between four 
and eight A.M. in a case of biliary fistula, just at the time when the 
patient wakened and commenced to move about, further supports the 
view that pressure on the liver may cause an increased flow of bile. 

Direct influence of nerves upon bile secretion.—It has already 
been pointed out that the secretion of bile may be indirectly modified 
by the influence of nerves upon the blood vessels. The flow of bile may 
also be increased through the stimulation of the nerves to the muscular 
coat of the bile ducts and gall bladder. Reflex stimulation through 
these nerves probably accounts for the first gush of bile after food is 
taken. There is, however, no evidence that stimulation of nerves can 
directly increase or diminish the actual secretion of bile—any change 
in the flow being fully explained by indirect action. The facts that 
the injection of pilocarpine, which so markedly increases the flow of 
saliva and of pancreatic juice, has no influence on bile secretion, and 
that atropine has no action in arresting the secretion,* seem to oppose 
the idea that there is any direct nervous influence upon the process. 

Influence of various chemical substances on bile secretion.— 
Certain substances, when introduced into the portal blood, either directly 
or through the alimentary canal, cause an increase in the secretion of bile. 

Tarchanoff® found that when hemoglobin is injected into the blood- 
vessels the bilirubin of the bile is increased in amount. Stédelman ® and 
Afanassiew 7 afterwards demonstrated that such drugs as toluylenediamin 
and arseniuretted hydrogen, which cause the solution of hemoglobin 
from the blood corpuscles, produce not only an increase in the bilirubin 
of bile, but also an increased flow of bile, and that this polycholia seems 
to be proportionate to the destruction of hemoglobin. It is therefore 
clear that the passage of free heemoglobin to the liver acts as a stimulant, 
and may produce an increased flow of bile; and hence all substances 
which bring about an escape of the blood colouring-matter tend to 
increase the secretion of bile. 


1 Hermann’s ‘‘ Handbuch,” S. 270. 

2 Rep. Lab. Roy. Coll. Phys., Edinburgh, vol. iii. p. 200. 

3 Paschkis, Med. Jahrb., Wien, 1884, S. 169. 

4 Rutherford, ‘‘ Action of Drugs on the Secretion of Bile,” Edinburgh, 1880, p. 96. 
5 Arch. f. d. ges. Physiol., Bonn, 1874, Bd. ix. 

® Arch. f. exper. Path. u. Pharmakol., Leipzig, 18838, Bd. xcviii. S. 460. 

7 Virchow’s Archiv, 1884, Bd. xeviii. S. 460. 


568 MECHANISM OF BILE SECRETION. 

Among these substances are the salts of the bile acids, and all in- 
vestigators find that the administration of these causes an enormous 
increase in bile secretion. But while such pure hemolytics as toluy- 
lenediamin and arseniuretted hydrogen cause only a transitory increase 
in the secretion, and produce a very concentrated bile, the bile salts not 
only markedly increase the solids, but also the water secreted. The 
following record of one of Rosenberg’s! experiments shows this effect :— 


fates ; : Per Cent. of Per Cent. of 
Time in Hours. Amount of Bile. water! Solids 
At 8.30-9.30 A.M. 4°7673 94°4 yA) 


10 grs. bile with 1-16 grs. 


solids given at 9.30 


i 9580210.30'!, 6°9095 95°3 4-7 
5 110.90=11.30's,, 12°9783 93°9 61 
y, 11.30 A.M.-12.30 P.M. . 3°6582 90°8 9-2 
, 12.30-1.30 P.M. . | 2°3897 88°9 111 


Again, Stidelman’s work shows that, while the ordinary hemolytics 
do not increase the secretion of bile salts, the administration of the 
bile salts leads to a marked increase in their percentage amount in the 
bile. Paschkis’ experiments? indicate that, while glycine and taurine 
have little action as cholagogues, cholalic acid is exceedingly active. It 
would thus seem that these substances act not only in virtue of their 
hemolytic action, but by reason of a special stimulating influence upon 
the liver cells. 

Salicylate of soda, which also has a hemolytic action, greatly 
increases the flow of bile. But while the bile salts cause an increase 
in the solids, this substance produces a very marked dilution of the 
bile (Rutherford,? Lewaschew,* and Rosenberg °). 

One of Rosenberg’s experiments is here given to show this effect. 


Time in Hours. Bile Secreted. | bday & Bees ue 

At 8-9 A.M... : : 1°2944 80°6 19°3 

, 9 » 2°0 ers. salicylate of soda given 

Pie TpGh wc sade due), 6°2885 90°7 9°3 

sl O— 1. 4°2914 92°3 ian 

,, 11 A.M.-12 noon 4°5218 92:1 7:9 

», 12noon-1 P.M. . 4°6437 91°8 8°2 

1 Loc. cit. 2 Loc. cit. 


3 <« Action of Drugs on the Secretion of Bile,” Edinburgh, 1880, p. 118. 
4 Zischr. f. klin. Med., Berlin, 1884, Bd. viii. S. 67. 
5 Arch. f. d. ges. Physiol., Bonn, 1890, Bd. xlvi. S. 355. 


GENERAL CONCLUSIONS. 569 


Rutherford, Vignal, and Dodds have experimented with a very 
large number of drugs, which were injected, dissolved in bile, into the 
duodenum.! The action of certain of these drugs has been re-investi- 
gated by Paschkis* and by Lewaschew,? whose results do not in all cases 
confirm those of the previous observers. It is, however, unnecessary to 
consider them in detail. Naunyn* sums up the matter by saying, 
“Many substances, when taken into the stomach, and more surely 
still when introduced into the duodenum (Rutherford), appear to pro- 
duce under certain conditions a slight increase of the biliary secretion. 
But the influence of these substances upon the secretion of bile is 
uncertain, and never a potent one.” 


GENERAL CONCLUSIONS. 


From a study of the mechanism of bile secretion, it is manifest that 
in its bile-producing function the liver differs from most other glands, 
since its activity is not under the direct control of the nervous system, 
but is modified by the ebb and flow of the blood stream, and by the 
influence of various chemical substances, such as the salts of the bile 
acids. 

The relationship of bile secretion to the other functions of the liver 
is in many points still obscure. That the disintegration of hemoglobin 
and the formation of bile pigments are closely connected, is definitely 
known (p. 563). That these two functions are connected with the 
production of urea, is shown by the fact that the administration of heemo- 
lytic agents, such as toluylenediamin, pyrogallic acid, etc., which increase 
the formation of bilirubin, cause a proportionate increase in the dis- 
integration of red blood corpuscles, and in the excretion of urea.® 

How far the formation of the amido-acids of the bile salts is con- 
nected with the disintegration of proteids, cannot be considered as 
settled, but the evidence adduced on p. 562 suggests that such a 
relationship exists. If this be the case, the formation of biliary con- 
stituents must be connected with the manufacture of glycogen and 
glucose from proteids. The formation of bile seems independent of the 
mere accumulation of carbohydrates in the liver. 

The various compounds of fatty acids in the bile are probably 
derived from the fatty acid compounds stored in the liver (p. 564). 
The nucleo-proteid, the mucin, and the cholesterin are probably to be 
regarded, not as true bilary constituents, but as products of the bile 
passages. As to the relationship of the inorganic salts of the bile 
with the other hepatic functions, nothing is known. 


1 Rutherford, Joc. cit. 2 Loe. cit. 3 Loc. cit. 
4 << Cholelithiasis,” translated by A. E. Garrod, New Syd. Soc., p. 172. 
° Noél Paton, Brit. Med. Jowrn., London, 1886, vol. ii. p. 207. 


THE CHEMISTRY OF THE URINE. 


By F. GowLANpD HOPKINS. 


Contents :—Introductory—Quantitative Composition of Urine, p. 572—Variations 
in its Amount and Specific Gravity, p. 573—Its Chemical Reaction, p. 574— 
The Nitrogenous Constituents: (a) Total Nitrogen, p. 580; (b) Urea, p. 581 ; 
(c) Ammonia, p. 585; (d) Uric Acid, p. 586; (e) Xanthin Bases, p. 596; (f) 
Creatinin, p. 598; (g) Hippuric Acid, p. 600; (1) Amido-Acids, p. 602—Pro- 
teids, p. 603—The Aromatic Substances, p. 605—The Carbohydrates, p. 607— 
Glycuronic Acid and its Conjugated Compounds, p. 613—Oxalic Acid, p. 614— 
Acids and Oxyacids of the Fatty Series, p. 615—Colour of the Urine and the 
Chemistry of its Pigments, p. 616: (a) The Preformed Pigments of Normal 
Urine, p. 618; (b) Chromogenic Substances, p. 626; (c) The Pigmentation of 
Pathological Urine, p. 628—The Inorganic Constituents, p. 630—General 
Characteristics of the Organic Urinary Compounds, p. 635—Comparative 
Chemistry of the Urine, p. 637. 


General considerations.—The chemical study of the urine gains its 
chief importance from the light which it throws upon the processes of 
metabolism. It is concerned mainly with a consideration of the nature 
and amount of the various metabolic end-products, normal or patho- 
logical, which converge into and appear together in the highly complex 
excretion of the kidneys. 

The great importance of this point of view has led to perhaps undue 
neglect of a second aspect of the subject—the consideration of the 
renal excretion as a complex whole; as a chemical fluid with individual 
characters of its own; characters which are not to be foretold from a 
knowledge of the nature and amount of each constituent considered 
separately, but require for their explanation the further consideration of 
the mutual effects of the constituents one upon another, as they exist 
side by side in solution. 

This study of the properties of the urine as a whole must be pursued 
if we are to understand with exactness the nature of the processes which 
go on in the kidney, and if we wish to interpret aright the ultimate 
behaviour of any given type of urine while in the urinary passages, or 
after it has left the body. 

But while the first-mentioned line of study requires in the main the 
services only of analysis—the earliest and best understood of the weapons 
of chemistry—the second depends upon our more recently won, and as 
yet very incomplete, knowledge of chemical statics, and of the conditions 
of equilibrium im salt solutions. 

All the chief proximate constituents of normal urine exhibit either 
basic or acid characters. Indifferent or “neutral” substances are norm- 
ally either absent, or present in minimal amount. The bases and acids 
present necessarily enter into more or less stable combinations, and it 


GENERAL CONSIDERATIONS. 571 


follows that the urine is essentially a solution of salts; its chemical and 
physical properties being those of a complex saline mixture. 

The chief bases are e potassium, sodium, and ammonium; calcium and 
magnesium ; urea, creatinin, and the xanthin bases. The chief acids are 
hydrochloric and sulphuric ; phosphoric and carbonic; uric; oxalic ; with 
hippuric and certain other aromatic acids. To the acid group belong also 
undoubtedly the pigments. 

The particular combinations formed in the urine by these various 
acids and bases depend primarily on their relative masses and avidities ; 
the ultimate equilibrium of the fluid depending, secondarily, on the 
mutual influences, in solution, of the salts which potentially tend to form 
as a result of the two factors just mentioned. It should be understood 
that our present knowledge does not carry us far towards a calculation 
of this complex equilibrium in any particular case. When we have 
determined by analysis the proportions of the various bases and acids 
present, we may, for convenience, group them into various supposititious 
combinations one with another, and speak of the urime as containing so 
much sodium chloride, so much “earthy phosphates,” and the like; but 
such groupings can, with our present knowledge, be for the most part 
approximate only; and, if insisted upon too closely, may be misleading. 

If the chemistry of urine had to be read merely as a final chapter 1 in 
the history of metabolism, the actual condition of the acids and bases 
present would be of little importance to the physiologist or to the 
pathologist. The nature and amount of these constituents having been 
determined, each would be considered in connection with the organ or 
tissue the metabolism of which is responsible for its appearance in the 
urine, and the chemistry of the latter would be of no further import. 

But the case, as we have said, is otherwise. The two conditions of 
chemical equilibrium represented respectively by the expressions— 


(1) CaSO,-+ 2(NaH,PO,) [three molecules] 
(2) Na,SO,+ Ca(H,PO,), [two molecules] 


involve each of them the same amount of the bases and acids concerned ; 
but the presence of the first combination in the urine might involve a 
renal activity quantitatively as well as qualitatively different from that 
which would be indicated by the presence of the latter. Further, a 
knowledge merely of the percentage of uric acid in a given specimen 
of urine will by no means give us final information as to the power of 
the fluid to retain this constituent in solution. One individual may 
excrete a large percentage, and yet have no tendency to suffer from 
uric acid gravel; another may not be free from this, though he habitually 
excrete a lower percentage. To explain this we must understand the 
influence of other urinary constituents on the solubility of uric acid; in 
other words, we must study the properties of the urine as a whole. 
Enough has been said to show that we are not to remain content 
with analytical figures alone. The future study of the urine will con- 
cern itself also with the application of facts derived from that domain of 
chemistry which deals with the distribution of chemical forces in com- 
plex mixtures. At present we have but little available knowledge of 
this kind, and many urinary phenomena are consequently but imperfectly 
understood. We may instance, however, a generalisation made from the 
experimental and mathematical investigation of the mutual influence of 
salts in solution, which is capable of immediate application to our subject. 


572 THE CHEMISTRY OF THE URINE. 


If two salts contaim an electrical ion in common (or without great inac- 
curacy we may say,a base or acid in common), each decreases the solubility 
of the other, whereas salts which contain no base or acid in common 
may mutually inerease each the other’s solubility. Thus the presence of 
sodium chloride in solution will diminish the solubility of sodium urate,! 
and ammonium chloride that of ammonium urate; but the presence of 
either of these chlorides will increase the solubility of (say) calcium 
phosphate. These laws will be found to have important application in 
the explanation of certain urinary phenomena. 

In addition to products which arise from metabolism in the tissues, 
the urine contains substances which are derived more directly from the 
ingesta. These comprise a large proportion of the normal inorganic 
constituents, which are always found in the diet in excess of the needs 
of the organism; and they may consist also of substances accidental or 
accessory to the diet, or again of drugs, or of substances experimentally 
introduced into the body. 

Some of these, while taking no share in metabolism proper, may 
form “conjugated” or synthetic compounds with certain intermediate 
products of metabolism, and so modify excretion. Thus glycin and 
glycuronic acid are substances capable of easy oxidation in the body, 
and are therefore not properly terminal products of metabolism; but 
they are protected from oxidation and are eliminated as synthetic 
compounds with certain aromatic substances, whenever the latter are 
absorbed in sufficient quantity from the bowel. 


QUANTITATIVE COMPOSITION OF THE URINE. 


The figures which follow are from the well-known table given by 


Parkes, representing the normal twenty-four hours’ excretion of the chief. 


urinary constituents :— 


Percentage Absolute Weight Weight per 

| or golids.  |f Solids in Grms.| pay weleht, 
| Urea, CH,N,O . | 45°75 33°18 0°5000 
| Creatinine, OE! gat S0 : : sil 1°25 0°91 0:0140 
| Uric acid, C,H N,0, : i . 0°75 0°55 0:0084 
Hippuric ar O,H ,NO, . : 0°55 0°40 0°0060 
| Pigment and other organic substances 13°79 10°00 0°1510 
Sulphuric acid, SO, 2°77 2°01 0°0305 
Phosphoric acid, IP oi. | 4°36 3°16 0:0480 
Calcium ‘ 0°35 0°26 0°0004 
| Magnesium : ’ t a il 0°28 0°21 0°0003 
pEctenceam ipl). cberycr ste: s2id tout 3°45 2°50 0°0420 
| Sodium 15°29 11°09 071661 
Chlorine . : : : : 10°35 7°50 0°1260 
Ammonia . : : : : oe 1°06 0°77 0°0130 
100°00 72°54 1°1057 


In the following analyses, derived from Bunge, all the figures were 
obtained from the same individual. They represent the twenty -four 
hours’ excretion of a young man; in the one case, upon a diet con- 
sisting entirely of beef with a little salt and spring water; in the 


1 As was shown experimentally by Sir William Roberts, before the general principle 
enunciated above had been developed by Nernst. 


oa oe 


URINE AND ITS SPECIFIC GRAVITY. 


‘ 


573 


other case, upon a diet of bread with a little butter, again with water 


as a beverage :— 


Meat Diet. Bread Diet. 
Total measure of urine in twenty-four hours 1672 c.c. 1020) crc. 
Urea 67°2 grms 20°6 grms. 
Creatinine 2163) 55, O°961 5, 
Uric acid . : : 1398: 35 O2538— % 
Sulphuric acid (total) 4674 ,, Te Z60.e os 
Phosphoric acid 3°437,, LOGE ope 
Lime 0°328' ,, 0°339 ,, 
Magnesia . 0°294 ,, O39) = 55 
Potash 3-308 ,, raya 
Soda SEI Ap 3°923 4, 
Chlorine . 3°817_,, 4:996 ,, 


These analyses are interesting as showing the effect of two widely 
differing forms of diet; but they must not be taken as typical of the 
relative effect of animal and vegetable diet in any absolute sense. As 
regards such factors, for instance, as the relative proportion between 
urea and uric acid, we shall find that, even when one or other of the 
two types of diet (animal or vegetable) is adhered to, great differences 
may be seen as the effect of variation in the specific composition of 
either. Indeed, no great importance must be attached to the details of 
collective quantitative analyses of the urine, except where the diet itself 
has been simultaheously analysed. While abundant observations of this 
kind have been published, relating to particular constituents of the 
urine, no collective analyses appear to have been made upon the same 
specimen of urine after a diet of known quantity and composition. 

The following figures, which give the mean of many determinations 
made by Yvon and Berlioz, show the differences in the excretion of 
certain constituents by males and females respectively :— 


MALE. FEMALE. 
Per Litre. Per Diem. Per Litre. Per Diem. 
Specific gravity 1:0225 1:0215 
Volume . 1360 e.c. 1100 e.e. 
Urea 21°5 grms. 26°5 grms. 19°0 grms. 20°5 grms. 
Uric acid OFF WE; OsGiins 33 OF555 oe On7OD 
Phosphoric acid a) ae dana DAN gt Dai 


THE QUANTITY OF URINE AND ITS SPECIFIC GRAVITY. 


A human adult excretes from 1200 to 1700 cc. of urine in the 
twenty-four hours, or about 1 cc. per kilo. of body weight per hour. 
During sleep the amount is less than at other times. 
gravity commonly varies from 1015 to 1025, and is, in general, inversely 


as the quantity excreted. 


The specific 


574 THE CHEMISTRY OF THE ORINE. 


Both factors, however, may vary through much wider limits than 
those given, without any departure from conditions of health. The 
chief causes which lead to increase of quantity and diminution of density 
are increased consumption of liquid and diminished activity of the sweat- 
glands. With abstention from liquids, or increased activity of the skin, 
the amount necessarily falls, and the density is raised. 

Increase in the quantity may follow, not alone from a heightened 
quantity of water in the blood, but from any influence, normal or 
pathological, which increases the blood flow through the kidneys. 

Pathologically the quantity is increased in diabetes mellitus and 
insipidus, in certain stages of chronic nephritis, and in some neurotic 
conditions; it is decreased in the early stages of acute nephritis, in the 
congestive condition of cardiac disease, and when large quantities of fluid 
are lost by the bowel, as in cholera. The specific gravity is increased in 
diabetes, and diminished in chronic nephritis. 


The specific gravity is roughly an indication of the amount of the 
urinary solids. It cannot indicate the amount with exactness, as the 
substances in solution are of various physical properties, and are not all 
capable of increasing the density in like proportions. Thus, while a 10 per 
cent. solution of common salt has (at 15°) a specific gravity of about 1073, 
a 10 per cent. solution of urea indicates only 1028.1 An increase in the 
urinary salines would therefore have a much greater effect in raising the 
specific gravity than a like increase in the urea. A knowledge of the actual 
weight of solids present seldom becomes of much importance. It may be 
obtained with sufficient accuracy by multiplying the last two figures of the 
sp. gr. by 2:2; the result indicating the total solid matter in grammes per 
litre. Thus a specimen of sp. gr. 1020 contains about 44 germs. per litre of 
substances in solution. 


CHEMICAL REACTION. 


Acids and bases are so proportioned in human urine that the mixed 
excretion of twenty-four hours generally reacts acid to htmus paper. It 
may sometimes exhibit the so-called amphoteric reaction—a phenomenon 
to be later discussed—but under strictly normal circumstances the 
accumulated excretion of the day is never alkaline to litmus. On the 
other hand, during limited periods of the daily cycle, it may sometimes, 
though not commonly, become alkaline. 

Litmus is reddened both by acids and by acid salts; but there are 
other coloured indicators which behave differently m the presence of 
free acids and acid salts respectively. When such are applied to urine, 
they show unequivocally that the former are never present, and we are 
thus forced to the conclusion that urine owes its acidity to acid salts. 
It will be shown immediately that we may conclude with some certainty 
that the reaction is due, as a matter of fact, to the presence of acid 
phosphates. 

The nitrogen, carbon, phosphorus, and sulphur of food-stuffs are all 
capable of oxidation to acid anhydrides, and the last three elements are 
in fact oxidised to this acidic form in the body. The chief product of 
the oxidation of carbon, carbon dioxide, may play a not unimportant 
role in the equilibrium of urinary acids and bases, and the existence of 
oxidised carbon in the molecules of certain organic compounds in the 

1A. H. Allen, ‘‘ Chemistry of Urine,” 1895, p. 12. 


CHEMICAL REACTION. 575 


urine confers upon them a definite acidic character. The acid oxides of 
phosphorus and sulphur, which are the chief end-products of the meta- 
bolism of these two elements, are eliminated almost entirely through 
the kidneys. Eighty per cent. of the total sulphur ingested, and nearly 
all the phosphorus, are eventually found in the urine as sulphuric and 
phosphoric acids respectively. That these acids are eliminated as salts, 
and not in the free state, depends in the main upon the fact that bases 
are continually being ingested in the food in a form available for the 
neutralisation of acids. The bases of the food are not all in the state 
of stable neutral salts. Even animal food contains basic phosphates, 
together with organic (proteid) combinations of the alkalies and 
alkaline earths, and small quantities of alkaline carbonates; while 
vegetable food contains, in addition, salts of the vegetable acids, which 
in the body are converted into carbonates by oxidation. By the 
ingestion of these unstable compounds of various bases, the organism 
is saved from the necessity of eliminating free mineral acids. When 
the supply of available bases is for any reason insufficient, a further 
protective mechanism comes into action, metabolism being so modified 
that a greater proportion of the nitrogen than usual is eliminated in 
the strongly basic form of ammonia. All these factors are normally so 
proportioned that, as we have seen, the urine, while containing no free 
acid, is acid from acid salts. 


Phosphoric acid (H,PO,) as a tribasic acid forms three orders of salts. 
Those in which two out of the three hydrogen atoms of the acid molecule 
are intact, are known as acid or superphosphates. They are soluble salts, and 
react acid to litmus. The second type, in which two hydrogen atoms are 
replaced by a base (monohydrogen phosphates), and the third, in which all 
the hydrogen is replaced (normal phosphates), are alkaline to litmus. While 
all varieties of the phosphates of sodium, potassium, and ammonium are freely 
dissolved by water, of the alkaline earth metals only the superphosphates 
are at all freely soluble. The monohydrogen and normal phosphates of 
calcium, magnesium, and, we may add, of barium, are scarcely taken up by 
water. 


If to a weak solution of, say, sodium - dihydrogen - phosphate 
(NaH,PO,) calcium chloride or barium chloride be added, no pre- 
cipitation occurs ; the corresponding salts of these latter metals being 
comparatively soluble. On the other hand, from a solution of di- 
sodium-monohydrogen-phosphate (Na,HPO,) nearly all of the phos- 
phoric acid is precipitated on the addition of a calcium or barium 
salt, in the form of the corresponding monohydrogen phosphate of the 
alkaline earth. In any mixed solution of di- and mono-hydrogen 
phosphates, the amount of phosphoric acid which is left unprecipitated 
by, say, barium chloride, is a measure of the proportion of the di- 
hydrogen phosphate originally present. Now, if we apply this test to 
urine of average acidity, we find that about 60 per cent. of the total 
phosphoric acid remains in solution after the addition of the barium 
chloride. We are justified in concluding, therefore, that acid di- 
hydrogen phosphates are present in about this proportion ; a fact in itself 
sufficient to account for the acid reaction of the fluid towards litmus. The 
composition of the barium precipitate from an acid urine proves that the 
remaining phosphoric acid is mainly in the form of monohydrogen salts. 

If, now, we suppose the excretion to receive an increased quantity 


576 THE CHEMISTRY OF THE CRINE. 


of the acid products of metabolism—what will be the effect on the dis- 
tribution of bases? It has been shown experimentally, that if to a 
mixed solution of mono- and di-hydrogen phosphates, a mineral acid 
(such as sulphuric acid) be added, in quantity not greater than is 
equivalent to the bases present in the monohydrogen form, no free acid 
is afterwards found in solution; but there will be an increase in the 
dihydrogen phosphates at the expense of the monohydrogen phosphates 
in proportion to the amount of acid added. Not only is this true of 
sulphuric acid ; it has been shown that all the weaker acids or acid salts 
which are liable to reach the urine from the circulation (e.g. hippuric 
acid or acid oxalates) are able, when added to a solution of the mixed 
phosphates, to remove base from the monohydrogen form, and so to 
produce almost an equivalent increase in the acid phosphates. So long, 
therefore, as both these types of phosphate exist side by side (and they 
are always found together in acid urine), we can assume that the 
acidity of the fluid is due to the acid phosphate, and practically to that 
alone. The simultaneous existence of the monohydrogen form will 
be seen to be a guarantee of this, as it will have to disappear by inter- 
change of bases, before any other urinary constituent can begin to exert 
its own proper acidity to any appreciable extent. 

When the urine reacts alkaline to litmus, the alkalinity may under 
different circumstances be due (1) to excess of basic phosphates, (2) to 
carbonates of the fixed alkalies, or (8) to ammonium carbonate. 

Determination of the acidity.!—It is, as we have seen, not difficult 
to assign the acidity of the urine to its proper cause; but when we 
endeavour to discover a method by which to estimate the degree of 
acidity, and especially a mode in which to express its value numeric- 
ally, we meet with considerable difficulties. 

In the case of a fluid the acidity of which is due to a strong acid, 
capable of forming stable salts with the alkalies, the ordinary methods 
of acidimetry yield a determinate result, and the estimation of acidity 
is one of the simplest operations in chemistry. We have but to note 
the amount of a standardised solution of alkali which is sufficient 
exactly to neutralise the acid present, and the point of neutralisation is 
given sharply and exactly by the colour change which occurs in the 
presence of one of many available indicators. In urine, owing to the 
unstable phosphate equilibrium, and the presence of other salts which 
influence the result, the process is much less determinate. To litmus, 
as already stated, a dihydrogen phosphate, e.g. NaH,PO,, is acid, while 
Na,HPO, and Na,PO, are alkaline; but no mixture of these salts can 
be found which is, strictly speaking, neutral to litmus paper. 

If we start with a urine acid to litmus and gradually add alkali, 
we at last reach a point when the fluid shows a paradoxical behaviour. 
It makes red litmus paper. tend to blue, and blue paper tend to red, 
inducing in fact a somewhat violet colour in both. It reacts at once 
acid and alkaline. This occurs when the monohydrogen phosphates, 
which during the addition of alkali are gradually increased at the 
expense of the dihydrogen salts, have come to bear a certain proportion 
to the latter. 

Many urines exhibit this so-called amphoteric reaction without the 


1 | have discussed this subject at what may seem disproportionate length, but the pro- 
blem involved illustrates well the complexity of chemical conditions in the urine ; and 
much has been written upon it of late on what I venture to believe are erroneous lines. 


DETERMINATION OF THE ACIDITY. 577 


addition of extraneous alkali. The reaction usually betokens that the 
monohydrogen salts exist in larger proportion than the dihydrogen, but it 
prevails through a considerable range of variations in this proportion ; 
its exact limits depending in part upon the delicacy of the litmus paper 
used. Throughout the range of the amphoteric reaction a solution of 
litmus, actually mixed with the fluid, retains a violet or neutral colour 
practically unchanged. 


Heintz attempted to explain this amphoteric reaction as follows. The 
red colouring matter of litmus acts as a dibasic acid, forming with bases, 
either unsaturated salts which are violet, or saturated salts which are blue. 
From the saturated salt the dihydrogen phosphates may extract half the base, 
leaving the unsaturated violet salt. The monohydrogen phosphates, on the 
other hand, may yield to the red acid substance sufficient base to form also 
the violet compound. In an amphoteric mixture the affinities are so balanced 
that this violet compound can alone exist. When, however, the acid phos- 
phate is present in sufficient excess, it removes all the base and leaves the red 
free acid ; with a large excess of the more basic phosphate, on the other hand, 
the litmus acid obtains its full complement of base and forms its blue salt. 


With other indicators we can obtain a colour change at a more 
definite point during the process of alkalisation of an acid urine, and to 
the use of these we shall shortly return. But it should be made clear 
that only in the interaction between a “strong” acid and a “strong” 
base is the colour change, with an indicator, synchronous (or approxi- 
mately synchronons) with the final replacement of all the acidic hydrogen 
atoms by the base. From this special case we have come to attach a 
definite value to the expression “degree of acidity,’ which is not 
found when we are dealing with such a substance as phosphoric acid. 
The “acidity ” is here a quantity varying with the indicator used. The 
coloured indicator is itself an unstable compound which, in the play of 
acid and basic affinities, suffers a definite change when a certain point 
of equilibrium is reached. This point will depend upon the relative 
stability of the indicator and of the phosphates with which it is in con- 
tact, and may or may not occur simultaneously with the removal of 
all replaceable hydrogen from the latter. 

The “degree of acidity” of a certain quantity of acid phosphate, in 
solution by itself, will be greater than that of an equal quantity mixed 
with a proportion of the more basic phosphates; and this is true, no 
matter what the indicator used. During the process of neutralisation 
by the standard alkali, the proportion of the more basic phosphates is 
gradually increased until the tendency of these to affect the indicator 
in one direction eventually balances the action of the acid phosphate 
in the opposite direction. This “neutral” point will evidently be 
reached the sooner, if some basic salt was originally present before 
titration was commenced. 

Such considerations as these have led to a proposal to estimate the 
acidity of urine, not by simple titration, but by actually determining the 
proportion between the acid phosphates and the more basic phosphates 
present. For this purpose, Lieblein,! after a careful study of the matter, 
has recommended the process of Freund, which is an application of the 
barium precipitation method referred to above. The total phosphoric acid 

1 Ztschr. f. physiol. Chem., Strassburg, 1895, Bd. xx. S. 52-88. In this paper a criti- 
cism of other methods will be found. 

VOL. I.—37 


/ 


578 PHE CHEMISTRY OF THE OIANE:. 


is first determined in the original urine; that existing as monohydrogen 
phosphates is then removed by precipitation with barium chloride, and 
that present as acid phosphates is finally determined in the filtrate. 

But how exactly are we to express the urinary acidity in terms of 
the results so obtained ? 

Some recent writers have denoted the acidity by the figure express- 
ing simply the ratio of acid phosphates to total phosphates? If the 
P.O; in the former be (say) 54 per cent. of the total P,O,, the relative 
acidity of the urine is to be called 54; if in another case it is only 27 
per cent., the acidity is to be considered as half that in the first case. 

Such a procedure seems to be wholly misleading. If of two 
specimens of urine one contains twice as much acid phosphate as the 
other, but at the same time twice the amount of the monohydrogen salt, 
the acidity, expressed in the above manner, will be the same in each ease. 

Such urines will certainly not behave as if of equal acidity, nor will 
they indicate the same acid production within the body. 


We may here illustrate what we mean by the expression “ behave as if of 
equal acidity.” One of the most important results of a high grade of acidity 
is a tendency for the urine to deposit its uric acid in the free condition. Ina 
later section, dealing with the urates (q.v.), the mechanism of this separation 
will be discussed. We shall find that one essential step in the process con- 
sists in the conversion of certain less acid urates (biurates) into more acid 
urates (quadriurates). 

Now it is the acid phosphates which bring this change about, by removing 
base from the first form of urate, themselves becoming, of course, converted 
part passu into more basic phosphates. But the latter, as they increase in 
quantity, tend to yield back the base to the quadriurates, so that a point is 
possible when the whole system will be in equilibrium. The less acid the 
urine, the sooner is this point reached. A little consideration will show that 
the ‘ degree of acidity,” from this point of view (and it is an important aspect), 
will be a function both of the absolute amount of the acid phosphates, and of 
the ratio they bear to the total phosphates. But we are hardly in a position 
to express the acidity quantitatively in terms of these two factors, because we 
do not know precisely at what stage the urates and phosphates are in equi- 
librium. It is probable, in fact, that the point of equilibrium is different for 
each of the diverse changes whith may occur in the urine, as a result of its 
acidity, just as it is different for the colour change in diverse indicators. No 
more striking instance of the relativity of the phenomena involved could be 
given than a fact we shall discuss under the head of the pigments. Urinary 
hematoporphyrin is always found in the so-called alkaline form ; and if we 
add to any normal urine either neutral or acid hematoporphyrin, we find 
that it immediately assumes the alkaline form. Equilibrium in this case is 
only attained when base has been transferred to the pigment from the acid 
phosphate. If, then, hematoporphyrin had happened to be our only available 
“indicator,” we should have said that urine was normally an alkaline fluid ! 


The whole source of the difficulty we have been discussing is found 
in the fact that the terms “degree of acidity” or “degree of alkalinity ” 
are unscientific, though convenient, modes of expression. With increase 
of knowledge, they will be replaced by expressions denoting the actual 


1 For the principles of this determination, see p. 633. An error of some 3 per cent. has 
to be allowed for, due to a conversion of monohydrogen into dihydrogen phosphate in the 
process of precipitation. 

2 Cf. Hausmann, Zischr. f klin. Med., Berlin, 1896, Bd, xxx. S. 350, 


VARIATIONS IN ACIDITY. 579 


chemical energy of the system of mixed salts. The degree of acidity of 
the urine (or any analogous fluid) is in fact not an absolute quantity, 
but is wholly relative to the means which we employ to measure it. 
But by always employing the same means, be it noted, we may obtain 
relative results which are strictly comparable, and as an outcome of this 
somewhat difficult discussion, it may be suggested that we shall do well 
in the present state of our knowledge to continue to employ a simple 
titration method, by which we obtain comparable, if only relative, 
measurements. But we must employ an indicator which gives a more 
definite point of colour change than does litmus, and we must retain 
the same indicator for any one series of experiments; moreover, the 
nature of the indicator used must always be stated in stating the 
results. Phenolphthalein, and perhaps cochineal, will serve our pur- 
pose. If acid urine be gradually neutralised in the presence of the 
former of these, which is colourless when acid, a pink tinge is developed 
at a certain stage in the process, and we are justified in speaking of a 
specimen of urine which requires more alkali to produce this change 
as “more acid” than one which requires less. 


What has been said in this section will have left a wrong impression if it 
be thought that such measurements are of no value. My endeavour has been 
to show that we have at present no means of expressing the acidity of the 
urine as an absolute quantity independent of the particular means adopted for 
measuring it. But, having chosen a method of estimation, and being careful 
always to use the, same method, we may accurately follow the variations of 
urinary acidity, and obtain results with important bearings. 


Variations in acidity.—The degree of acidity as determined by 
titration is, as we have seen, in the main, a resultant of two opposing 
factors; on the one hand, acid production in metabolism; on the other, 
the ingestion of unsaturated or unstable basic compounds, supplemented 
by the production of ammonia within the body. To these, however, a 
third factor must be added—the elimination of acids or bases respect- 
ively by other than renal channels. 

The separation of the acid gastric juice and the consequent libera- 
tion of bases in the blood is associated with increased excretion of the 
latter in the urine. On the other hand, the flow of alkaline secretions 
—hile, pancreatic juice, etc.—diminishes the urinary bases. 

From these considerations, the reasons for the variations in acidity 
commonly met with become clear. The acidity increases with increased 
proteid metabolism, with exercise, and with the consumption of food, 
when this contains a small proportion of bases—in particular, with flesh 
food. It diminishes when the food taken contains abundant bases. The 
compounds of organic acids with the alkaline metals, which are so 
plentiful in vegetable food, become oxidised in the body to carbonates, 
and the excretion of bases thence derived tends to alkalise the urine. 
From this follows the familiar fact that the urine of herbivorous 
animals is alkaline, and that human urine may become alkaline (though 
seldom continuously so) when a vegetarian diet is maintained. 

The effect of the secretion of gastric juice is to produce what is called 
the alkaline tide. During the period of full gastric digestion the urine 
may become less acid, and may even (though this is rare) become alka- 
line to litmus. The occurrence of this phenomenon was first noted by 
Bence Jones. 


580 THE CHEMISTRY OF THE URINE. 


It must not be supposed, however, that the post-prandial alkaline 
tide is a universal phenomenon. It will be easily seen that the effect 
of digestion upon the bases and acids of the blood must be somewhat 
complex. The flow of alkaline saliva precedes, and that of bile and pan- 
creatic juice rapidly follows, the gastric secretion ; and these, by removing 
bases, tend to neutralise the effect of the removal of acid vid the 
stomach. From this cause, and from the increased proteid metabolism 
induced by the food, it not infrequently happens that the urinary acidity 
is from the first raised, instead of lowered, after a meal. 

According to Quincke, a periodic variation of acidity may occur dur- 
ing the day, independently of food ingestion, and in my experience this 
is a more constant phenomenon. 

Gruber found that the urine may become alkaline after a large con- 
sumption of sodium chloride, and Riidel? has recently stated that the 
pure diuresis produced by such substances is in itself capable of inducing 
this result. This may be true, under the somewhat extreme conditions 
of experiment, but when the urinary constants are followed under 
natural conditions from hour to hour, it is not found that the quantity 
of urine passed during a given period has any regular influence on the 
total acidity of the same period.? 


Pathologically, a tendency to alkalinity is said to be found in most con- 
ditions of debility, and especially in some types of anemia; probably from 
diminished secretion of gastric juice, and from diminished general metabolism. 
A process quite distinct from this occurs when, under the influence of 
organisms (especially the Micrococcus wre), the urea and uric acid of the 
urine are hydrolised into ammonium carbonate. In cystitis this may occur 
in the bladder, and the urine is voided alkaline with ammonia. 

The acidity is especially high in scorbutic urine, and is increased to a greater 
or less degree in some forms of dyspepsia, in diabetes, leukemia, and in per- 
nicious anemia. 


THE NITROGENOUS COMPOUNDS. 


(a) Total nitrogen.—The urinary nitrogen amounts, on an average, 
to 15 germs. in the twenty-four hours. This comprises by far the greater 
part of the nitrogenous loss to the body; less than 1 grm. being eliminated 
through the intestinal secretions and all other channels combined. 

Pathologically, the amount may be greatly increased ; 20 to 25 grms. 
per diem is frequently observed in fever, and in severe forms of diabetes 
50 grms. and upwards may be daily eliminated. On the other hand, a 
marked diminution of the amount is seen in the condition of contracted 
or granular kidney. 

Under normal conditions, the urinary nitrogen is distributed in 
various compounds in the following proportions: About 86 per cent. of 
the whole is found in the form of urea; about 3 per cent. as ammonia, 
3 per cent. as creatinin, 2 per cent. as uric acid and the allied xanthin 
bases ; while the remaining 6 per cent. is present, in varying proportions, 
in hippuric acid, in indol and skatol, in the urinary nucleo-albumin, 
in the pigments, and in minute quantities of other constitutents. 


The total nitrogen is estimated by one of the many modifications of 
Kjeldahl’s process, which is founded on the fact that organic substances, 


1 Zischr. f. klin. Med., Berlin, 1884, Bd. vii. Suppl. 22. 
2 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1892, Bd. xxx. S. 41. 
2 Cf. Hausmann, Zétschr. f. klin. Med., Berlin, 1896, Bd. xxx. 8S. 362. 


UREA. 581 


when heated with concentrated sulphuric acid, become oxidised, and all the 
nitrogen (except sich as may be originally present in combination with 
oxygen) is converted into ammonia. The resulting ammonia is liberated 
by the addition of caustic alkali, and distilled into a measured quantity of 
standard acid; its amount being finally determined by titration. Kjeldahl’s 
method gives admirable results with urine, and may be applied to 5 c.c. of 


the fluid. 


(b) Urea— Fe ras first 
demonstrated by Rouelle in 1775. It is the chief end-product of nitro- 
genous metabolism in all mammals, in amphibia, and in fishes. In 1828 
it was obtained artifically by Wohler, by heating the isomeric substance 
ammonium cyanate (NH,CNO). 

The chemical constitution of urea is that of an amide of carbonic 
acid (carbamide). 

Properties.— Urea crystallises in colourless needles or rhombic prisms, 
containing no water of crystallisation, and melting at about 130° C. It 
is freely soluble in alcohol, and still more so in water; in pure ether or 
chloroform it is insoluble. Urea, like other amides of acids, is neutral 
to htmus; but, owing to the presence of two ammonia residues in its 
molecule, it exhibits weak basic properties, and forms loose molecular 
compounds, analogous to salts, two of which are of practical im- 
portance. 

Urea nitrate = CO(NH,),.NO,,0H.—This compound crystallises out 
when excess of pure nitric acid is added to a not too weak solution of 
urea; excess of the acid assists its separation, as it is less soluble in 
nitric acid than in water; crystallisation is accelerated by shaking and 
cooling the mixture. The fundamental form of the crystals is a rhombic 
table, of which the more acute angles measure 82°; but, by truncation 
of the angles, six-sided tablets are commonly formed, and these are apt 
to adhere together and overlap like tiles on a roof (Fig. 49). When 
rapidly heated, the crystals deflagrate. At 140° they decompose into 
nitrous oxide, carbon dioxide, and ammonium nitrate. 

Urea oxalate = CO(NH,),.(COOH),—is formed in an analogous 
manner by mixing solutions of urea and oxalic acid; like the nitrate, 
this salt is less soluble in excess of the acid. Its crystals belong funda- 
mentally to the same type as those of the preceding compound, but are 
apt to appear as thick short rhombic prisms (Fig. 49). 


A crystalline combination of urea with phosphoric acid is also known, and 
others with various organic and inorganic acids. 

Crystalline compounds are also ‘formed with certain neutral salts; that 
with sodium chloride is said occasionally to form when urine is concentrated 
on the water bath. The compound with palladium chloride is very insoluble. 
A molecular combination with basic mercury nitrate is quite insoluble in water, 
and is of historic interest, as its formation is the basis of the classical method 
of urea estimation suggested by Liebig in 1853 (vide infra). 


When fused and gently heated after fusion, urea yields biuret and 
cyanuric acid. Two reactions occur as follows :— 


2NH,.CO.NH, = NH,.CO.NH.CO.NH,+H,N: and 
(biuret) 


3NH,.CO.NH, = C,N,(OH), +3(H,N) 


(cyanuric acid) 


582 THE CHEMISTRYVIOF THE CRINE. 


Its relations to ammonium carbonate and carbamate are very im- 
portant from a physiological standpoint. 


NH, NH, NH, 
COS 28. Care cok Bieeta))= cot 
NH, NH, ONH, 
(urea) (ammonium carbamate) (ammonium car Hone) 


The two molecules of water necessary to form carbonate of ammonia 
are very readily taken up. Even at a temperature of 60° C., an aqueous 
solution of urea slowly develops ammonia (Leube'); while a boiling 
solution decomposes with considerable rapidity. Heated with water 


Fic. 49.—Upper half, urea nitrate crystals. Lower half, urea oxalate 
crystals. 


under pressure at 180°, the conversion into ammonium carbonate is 
quickly complete. A solution of pure urea may be evaporated at tem- 
peratures from 60° to 75°, without serious loss, but in the urine it is less 
stable. Quite appreciable proportions of its nitrogen are lost as ammonia 
when urine is evaporated, even at low temperatures. In the presence 
of free acids and bases, the hydrolysis occurs with still greater readiness, 
the ammonium carbonate formed being further decomposed by the 
reagent. Thus, on boiling urea solutions with acids, carbonic acid is 
given off; on boiling them with alkalies, free ammonia is evolved. 

The hy drolysis is also induced by micro-organisms, as in the 
ammoniacal fermentation of urine. The Micrococcus wree is the best 
known of these; but other organisms are found in decomposing urime 


1 Virchow’s Archiv, 1885, Bd. c. S. 552. 


UREA. 583 


which can produce the same result. On the other hand, urine may 
develop many organisms which have no such power.t So long as the 
bacteria which induce the change are alive, the enzyme is closely 
associated with the living cell, and a filtered urine is ferment free 
(Sheridan Lea). But when the cells are dead, a ferment may be 
extracted from them which hydrolyses pure urea solutions. 

While urea is thus easily converted into ammonium carbonate, the 
intermediate substance ammonium carbamate (formed by the action of 
dry CO, upon NH,), if heated to 135°, or treated with alternating electric 
currents, splits up into urea and water. The hepatic cells have the 
power of dehydrolising ammonium carbonate itself to form urea. Nitrous 
acid and the hypobromites oxidise urea according to the following 
equations :— 

(1) CO(NH,),+2NOOH=CO,12N,13H,0 
(2) CO(NH.,),+3BrONa=3NaBr+CO,+N,+2H,0 


Separation of wrea.—To prepare pure urea from urine, advantage may 
be taken of the insolubility of the nitrate. The urine is concentrated to a 
small bulk, and pure nitric acid is added in excess; the mixture being kept 
thoroughly cool during the addition of acid. The crystals are strained off by 
pouring through muslin, and freed from excess of acid by pressing between 
thick filtering paper. They are mixed with excess of barium carbonate, 
sufficient alcohol is added to form a paste, and the mixture dried on the water 
bath. On extracting the dried residue with absolute alcohol, a fairly pure 
solution of urea is obtained, from which crystals separate on evaporation. 

I find that fine crystals may be prepared by the following simpler method. 
Half a litre of urine is evaporated to a thick syrupy consistence, and the 
residue is exhausted with hot absolute alcohol. The spirit is filtered and 
taken to dryness ; and the residue extracted on the water bath with successive 
quantities of pure acetone, which should be filtered while hot. The mixed 
acetone extracts are evaporated nearly, but not quite, to dryness. On cooling, 
fine white crystals of urea separate, any pigment present remaining in solution 
in the small quantity of the solvent which is allowed to remain. The crystals 
may be washed with cold acetone. 


Tests—For the detection of urea, the formation of the characteristic 
erystals of the nitrate or oxalate (and especially of the former) is of 
practical value. On the small scale the process of crystallisation may 
be watched under the microscope; a drop of the suspected fluid, after 
concentration if necessary, and another of nitric acid, being allowed to 
run together on a glass slide. 

The formation of biuret is an excellent test for urea, if the crystals 
are first obtained in moderate quantity and fairly pure. After heating 
them, as described above, the residue is dissolved in water, excess of 
caustic alkali is added, and one or two drops of a dilute copper sulphate 
solution. A pink colour is produced like that given by peptones under 
like circumstances (“ biuret reaction ”). 


Estimation of wrea.—No method is known by which urea can be separated, 
as such, from the urine in a quantitative manner. The ease with which it is 
hydrolised is a fundamental difficulty in the way ofsuch quantitative isolation. 
We can, however, find precipitants for the other nitrogenous constituents, and 
a determination of the remaining nitrogen after the removal of these gives the 
best available measure of the urea. 


1 For information on this subject, wide Leube and Graser, Virchow’s Archiv, loc. cit.; and 
Warrington, Journ. Chem. Soc., London, 1888, vol. i. p. 727. 


584 THE CHEMISTRY OF THE CLINE. 


The most satisfactory of the methods based upon this principle is that of 
Morner and Sjoquist.!. To carry out this process, 5 c.c. of the urine is treated 
with an equal volume of a saturated solution of barium chloride containing 
5 per cent. of caustic baryta; 100 c.c. of an alcohol-ether mixture (2-1) is 
added, and the whole allowed to stand for twenty-four hours in a closed flask. 
After filtermg from the precipitate the solution is evaporated at low tem- 
peratures (below 60°), and a determination of nitrogen made, by Kjeldahl’s 
method, in the residue. By the precipitation thus described all nitrogenous 
substances are removed except urea and ammonia, while the last is got rid of 
during the evaporation of the filtrate. The percentage of nitrogen found 
multiplied by 2°143 will give the percentage of urea. 

When less accuracy is required, the well-known process of Knop? and 
Hiifner is now universally employed. This depends on the decomposition of 
urea by the action of hypobromites ; the nitrogen which is evolved being 
measured in a graduated tube, and the urea calculated from the amount thus 
found. The equation for this reaction is given above (p. 583). The solution 
of sodium lrypobromite employed contains excess of caustic alkali, so that 
the carbon dioxide which is formed simultaneously with the free nitrogen, 
is retained in solution as carbonate of sodium. Only some 92 or 93 per 
cent. of the total nitrogen present as urea is obtained in this process, the 
remainder being converted into cyanates. On the other hand, the uric acid, 
creatinin, and other nitrogenous substances present yield a proportion of their 
nitrogen, so that part of this error is counterbalanced. Many varying in- 
fluences affect the result, however; diabetic urine, for instance, is said to 
yield a greater proportion of its total nitrogen, owing to the effect of the 
sugar present. It should, in fact, be clearly understood that the hypobromite 
process, while of great convenience and of sufficient accuracy for clinical and 
many other purposes, does not give a scientific measure of the urea. The 
calculation of its results is best made by taking each 37°1 cc. of nitrogen 
measured at ordinary temperatures as equivalent to one decigramme of urea.® 

The titration method of Liebig referred to on p. 581 is now of little more 
than historical importance, though it was used in all the older work upon 
metabolism. It depended in principle on the fact that urea, under carefully 
defined conditions, forms a definite insoluble compound with basic mercuric 
nitrate. A standard solution of nitrate of mercury was added to the urine 
until the whole of the urea was precipitated in this form, the end-point being 
marked when a drop of the urine gave a yellow colour with sodium carbonate 
(indicating excess of mercury). The modifications necessary for accuracy have 
been carefully worked out by Pfliiger and others ; in its perfected form, however, 
the process becomes one for the estimation of the total nitrogen of the urine 
rather than for the urea only, and for this purpose it is entirely superseded by 
Kjeldahl’s method (supra, p. 580). 


The variations in the quantity of urea present in the urme are 
dealt with in the article on metabolism, where their cause is dis- 
cussed. The average quantity excreted by a healthy adult man under 
normal circumstances is about 30 grms. per diem; that is to say, the 
urine will contain about 2 per cent. Its absolute amount is necessarily 
increased by all causes which stimulate nitrogenous metabolism, but the 
proportion which the urea bears to the other nitrogenous constituents is 
an independent variable (vide infra). 

1 Skandin. Arch. f. Physiol., Leipzig, 1891, Bd. ii. S. 488 ; Jahresb. d. Fortschr. 
d. Thier-Chem., Wiesbaden, Bd. xxi. 8. 168; ef. also Bodtker, ’ Ztschr. Ui hiya Chem., 
Strassburg, 1893, Bd. xvii. 8S. 146. 

* The original description by Knop will be found in Chem. Centr.-Bl., Leipzig, 1860, 


S. 244. Details of various modern modifications are found in most practical handbooks. 
3 Cf. A. H. Allen, ‘‘ Chemistry of Urine,” p. 148. 


AMMONIA. 585 


According to Tschlenoff; if the urea excretion after a meal rich in 
proteids be estimated from hour to hour, it will be found to exhibit two 
maxima. The first occurs at the third or fourth hours, and the second at 
the sixth or seventh. These he considers to indicate the absorption of 
peptones from the stomach and intestine respectively. If peptones be 
given instead of otdinary proteids, the maximum is reached’ by the second 
hour. Marés? on the other hand, found that after an isolated meal the 
maximum of urea excretion was not reached till the ninth hour. 
Kobler ? has found that simple diuresis under normal circumstances is 
not accompanied by increased excretion of urea. 

(c) Ammonia.— The urine of man and of carnivorous animals 
invariably contains small quantities of ammonium salts. They may 
be absent, however, from that of herbivora. The quantity in human 
urine is about 0°7 grm. NH, per diem; the variations in health extend- 
ing from about 0°35 to 1-2 grms.* 

The ingestion of ammonium carbonate, or of organic ammonium 
compounds susceptible of oxidation in the body, does not imerease the 
excretion of ammonia, for the nitrogen of such compounds is excreted 
wholly as urea. If, however, stable salts of ammonium, such as the 
chloride, are given, they appear (in the case of carnivora, at any rate) as 
such in the urine. 

Apart from such direct ingestion of stable ammonium salts, the 
excretion of ammonia depends almost entirely upon that question of 
adjustment between acid production in metabolism and the supply of 
bases in the food which was discussed in the section devoted to the 
acidity of the urine (q.v.). Ammonia formation is the physiological 
remedy for deficiency of bases. 

When acid production is excessive (a condition especially seen in 
certain forms of diabetes), or when mineral acids are given by the 
mouth, the urinary ammonia increases at the expense of the urea. 
When the bases are in excess, whether from the nature of the food or 
from the administration of alkalies, the ammonia disappears, and a corre- 
sponding amount of urea is excreted in its place. From this it follows 
that little or no ammonia is found in the urine of herbivora; and that, 
in man, flesh food raises the quantity, and vegetable food diminishes it.? 


From the abundance of bases in their food, it is very difficult, by any 
means, to increase the urinary ammonia of herbivora. If, for example, 
abundant ammonium chloride be given to a rabbit, together with a normal 
supply of vegetable food, its urinary ammonia is but little increased.© By 
double decomposition with sodium carbonate in the tissues, ammonium car- 
bonate and sodium chloride are formed, and the former is excreted as urea. 

It would seem that the organisation of the hherbivora does not permit of 
a supply of ammonia to neutralise acids when given in excess. Thus, most 
herbivorous animals are said to be much more susceptible to poisoning by 
acids than are the carnivora. 


1 Abstract in Centralbl. f. Physiol., Leipzig u. Wien, 1896; cf. also Veragutt, Journ. 
Physiol., Cambridge and London, 1897, vol. xxi. p. 112. 

2 Jahresb. ii. d. Leistung. . . . d. ges. Med., Berlin, 1887, Bd. i. S. 145. 

3 Wien. klin. Wehnschr., 1891, Nos. 19, 20. : 

4 Neubauer, Journ. f. prakt. Chem., Leipzig, 1852, Bd. lxiv. S. 177. These figures are 
confirmed by numerous later observers. 

5 Salkowski and Munk, Virchow’s Archiv, 1877, Bd. lxxi. S. 500; also Gumlich, 
Ztschr. f. physiol. Chem., Strassburg, 1893, Bd. xvi. S. 19. 

6 BE. Salkowski, Ztschr. f. physiol. Chem., Strassburg, 1877, Bd. i. S. 26. 


586 THE CHEMISTRY OF THE CRINE. 


To demonstrate the presence of the small quantities of ammonia in 
human urine is not easy, owing to the ready production of the base 
by hydrolysis of urea, which must, obviously, lead to error. We must 
employ a method analogous to that used for its estimation. 


Estimation of ammonia (Schlising’s method).—Twenty-five c.c. of urine are 
placed in a basin with vertical sides, and about 20 ¢.c. of milk of lime are 
added. A glass triangle is placed over the basin, and, upon it, another small 
vessel containing 20 c.c. of one-fifth normal sulphuric acid. These stand 
upon a glass slab, and are covered with a bell-shaped glass cover, fitting air- 
tight on the slab. The ammonia is liberated by the lime, without any 
decomposition of other nitrogenous constituents, and, in the course of three 
days, the whole is absorbed by the sulphuric acid, the degree of neutralisation 
being afterwards estimated by titration. If dilute hydrochloric acid be 
used instead of sulphuric, it may, after the experiment, be evaporated to 
dryness on the water bath, and the residue taken up with a small quantity of 
water. Platinic chloride added to this solution will demonstrate the presence 
of ammonia, by giving a yellow crystalline precipitate of ammonio-platinic 
chloride. 

Pathologically, the urinary ammonia may be increased, not only after the 
manner we have discussed, by abnormal acid production (as in diabetes and 
fevers), but also by conditions which reduce the proper activity of the 
hepatic cells, whereby the dehydrolysis of ammonium carbonate into urea is 
less complete than normally. 


(a) Uric acid.—Uric acid was first separated from human urine by 
Scheele, in 1776. It is present in the urine of most mammals, though 
from that of the dog and cat it has been shown to be frequently absent. 
In man the daily output in the urine varies considerably (from 0°2 grm. 
to 1:4 grm.), the average amount being 0°8 grm. 

Chemical constitution. —Rightly to “appreciate the physiology no less 
than the chemistry of uric acid, its close relationship to urea should be 
clearly understood. It yields the latter e easily by a combined process of 
oxidation and hydrolysis. It belongs, in fact, to the class of substances 
known as diuréides, in which the residue of two urea molecules are 
united to a carbon-containing nucleus. In the case of uric acid this 
nucleus contains a chain of three carbon atoms. 

The constitutional formula first suggested by Medicus— 


NH—C—NH. 

| | 7CO 
CO C—NH% 

| | 

NH—CO 


has now received ample confirmation from the synthetic production of 
the acid by Horbaczewski,! and by Behrend and Roosen.? 

The ureides are, in eeneral, produced by the condensation of hydroxy- 
acids with urea. The hypothetical acid, which would yield uric acid 
by such simple condensation, would be a trihy droxyacrylic acid; but 
this has never been prepared. 

Lactic acid also contains a three-carbon chain in its molecule, and, 
because of the important physiological relationships of this acid, it is of 
special interest to find that uric acid can be synthesised by linking urea 


1 Monatsh. f. Chem., Wien, 1887, Bd. viii. S. 201, 584. 
2 Ber. d. deutsch. chen. Gesellsch., 1888, Bd. xxi. S. 999. 


URIC ACID. 587 


residues on to a nucleus derived from lactic acid. This Horbaczewski 
succeeded in doing by heating urea with trichorlactamide : 


OCL.,CH.OH.CO.NH,+2(NH,),CO=C;H,N,O,+NH,Cl+2HCI+H,0 


The simple changes involved in this reaction will be more clearly seen on 
examination of the following graphic scheme :— 


Cl 
oie C1.C.Cl HNH, 
| | Joo 
co CH(OH) HNH 
| | 
HNH CONH, 
(urea) (trichlorlactamide) (urea) 


The groups printed in thick type unite to form uric acid; the atoms repre- 
sented in thinner type split off to form respectively a molecule of ammonium 
chloride, two molecules of hydrochloric acid, and one of water. 


Urie acid is formed also when glycine is heated with urea (Hor- 
baezewski), but the molecular changes involved are not so simple 
as those shown above, and the yield is not so good. In Behrend and 
Roosen’s synthesis the nucleus is primarily derived from acet-acetic 
ether, and the urea residues are linked on separately at two different 
stages in the synthetic process. 

Properties.—Pure uric acid forms a white powder, which is made up 
of small rhombic crystals, of more or less prismatic or tabular type. Its 
crystallme forms become very diverse in the presence of impurities, 
and when it separates from the urine, the crystals, which are then always 
coloured, take shapes which depend to a large extent upon the nature of 
the pigment associated with them?! (Figs. 50 and 51). 

In cold water it is very in- 
soluble, only dissolving to the ex- 
tent of about 1 part m 15,000. 
A litre of boiling water takes 
up about half a gramme. Ether 
and alcohol do not dissolve it. It 
dissolves in oil of vitriol without 
decomposition, and from the solu- 
tion a crystalline sulphate separates 
on freezing the mixture. By this 
process pure uric acid may be 
obtained from contaminated speci- 
mens, the sulphate being resolved 
into its constituents when treated 
with water. 

It acts as a somewhat weak 
dibasic acid, but forms three orders Fie. 50.—Uric acid. 
of salts. 

1. The neutral urates, M’,U, have an intense caustic taste and are 
very unstable. They are decomposed by carbonates and even by the 
carbonic acid of the air. As they are only produced in the presence of - 
caustic alkalies, and cannot exist in the presence of carbonates, it is un- 


1A. E. Garrod. 


588 THE CHEMISTRY OF THE URINE. 


likely that they can, under any circumstances, occur as physiological 
products.t 

2. The acid wrates or biwrates, M’HU, are the most stable of the com- 
pounds of uric acid. They are prepared by dissolving the acid at boiling 
heat in weak solutions of the alkaline carbonates, from which they 
separate, after cooling, in stellar crystals. These and the foregoing salts 
were first studied by Bensch and Allan.? The acid urates are less 
soluble than the neutral salts. i 

3. The quadriurates, H,U,M’HU.—These hyperacid salts, for the ex- 
istence and importance of which we have now satisfactory evidence, were 
first described by Scherer,’ and (independently) by Bence Jones,* but 
they have since been more carefully studied by Sir Wm. Roberts. 
They are best prepared by boiling uric acid with dilute solutions of 
acetate of potassium, and from solutions so obtained a quadriurate 
separates, as an amorphous precipitate, or in crystalline spheres.6 They 
are very unstable, and when treated with water they split up into 
biurates and free uric acid. Owing to this instability it is impossible to 
determine directly their solubility in water; but they are probably less 
soluble than the preceding order of salts, as a strong solution of a 
biurate, when treated with acid-sodium phosphate, gives an abundant 
precipitate of a quadriurate. From analogy we might expect the three 
orders of salts, as described, to be in a descending series as regards 
solubility. 

Condition of uric acid in the urine: its spontaneous separation. 
Coloured indicators which are sensitive to free uric acid give no 
indication of its presence, as such, in freshly-passed urine. Again, the 
quantity of uric acid present is generally greatly in excess of what 
would dissolve ina volume of water equal to that of the urine. The 
presence of neutral salts, and also, according to Riidel,’ of urea, enhances 
this solubility, but not to a degree necessary for the retention of all the 
urinary uric acid in solution. We are led to expect, therefore, that it is 
present not as free acid but as a more soluble compound. Neverthe- 
less, most urimes will, on cooling and prolonged standing, deposit a 
certain (and sometimes a large) proportion of their uric acid in a free 
condition. 

We have to explain, therefore, the nature of the original solution and 
the cause of the subsequent separation. The view generally held till 
recently, and still current with some authorities, is that the acid exists as 
biurates; and that these are slowly decomposed, with liberation of the 
free acid, by the action of the acid phosphates, according to the following 
simple reaction :— 


MHU +MH,PO,=H,U+M,HPO, 


From acid urines, however, the uric acid is frequently deposited, in 
the first place, not as free acid, but in the form of urates, forming a 
precipitate which has long been known as the “ lateritious deposit.” 

A careful study of the chemistry of this deposit has led Sir Wiliam 
Roberts to conclude that the above equation does not rightly, or at least 


1 Roberts. 2 Ann. d. Chem., Leipzig, 1848, Bd. Ixy. 8. 181. 

* Neubauer ii. Vogel, ‘‘ Analyse des Harns,” 9th edition, S. 192. 

* Journ. Chem. Soc., London, 1862, vol. xv. p. 8. 

© “Croonian Lectures,’”’ 1892. 6 Thid. 
7 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1892, Bd. xxx. S. 469. 


URIC ACID. 589 


does not completely express the chemical mechanism of uric-acid solution 
and precipitation.i 

The urate deposit is amorphous, but on treatment with water it is 
found to decompose, part of its uric acid being set free in crystalline 
form and part going into solution (Fig. 51). But this is a property which 
was stated above to be specially characteristic of the quadriurates, and 
closer examination shows that the greater part of an amorphous urate 
deposit does, in point of fact, consist of those hyperacid salts, and not 
of ordinary biurates. 

Roberts’ view is that the quadriurate is the only physiological type 
of uric acid salt, whether in blood or in urine. 


Fic. 51.—Uric acid.—In the lower half of the figure the crystals are 
shown as they separate when a quadriurate deposit is decomposed 
with water. 


In the normal acid urine, immediately after its secretion, all the uric 
acid is in this form. But in aqueous solution the quadriurates are neces- 
sarily in a state of unstable equilibrium, and tend at once to decompose 
according to the equation— 


(1) MHU,H,U =MHU+H.U; 


half the uric acid being precipitated and the other half remaining in 
solution as biurates. But the latter are in the presence of acid phos- 
phates, and this fact again involves a condition of unstable equilibrium; 
the following change occurring— 


(2) MHU+MH,PO, = MHU,H,U +-M,HPO,. 


1 Roberts, oc. cit. 


590 THE CHEMISTRY OF THE ORINE. 


In fact, quadriurates are thus re-formed, and become subject to the 
same influences as before. “These alternating reactions—breaking up 
of quadriurates by water into biurates and free uric acid, and recomposi- 
tion of quadriurates by double decomposition of biurates with mono- 


metallic phosphate—go on progressively, until all the uric acid may be 


set free.” 


The quadriurates, therefore, are of great importance in the chemistry of 
urinary uric acid, and beyond all doubt form an intermediate step in the 
liberation of the free acid itself. The evidence that they are the form in 
which the acid is actually excreted seems to be less conclusive. It is clear 
that the alternating reactions just discussed would go on, whether the salts 
which leave the renal tubules are quadriurates or biurates. In the latter case, 
the interaction with the phosphates would be the first stage of the process, 
and the decomposition of the resulting quadriurates the second. Equations 
(1) and (2), above, would occur in reversed order, and the alternation would 
then continue as before. The fact that the solid excretion of birds and snakes 
consists of quadriurates,! may be held to support the view that these salts 
are the excretory form in man, as also the observation that certain urate con- 
cretions found in the kidneys of new-born children approximate in composition 
to the quadriurates.? But it may be fairly argued that when, as in the 
human adult, the mechanism of excretion has become more perfectly suited 
to the elimination of a liquid urine, the uric acid will tend to assume the 
more soluble form, and all the evidence points to the fact that this form is 
the biurate. I have frequently observed that when ammonium urate separates 
from a clear acid urine, as an effect of adding neutral ammonium chloride in 
excess (vide infra), it is wholly in the form of a biurate. While it is not 
inconceivable that a migration of bases occurs under these circumstances, it 
is far more likely that the fact points to the pre-existence of biurates in the 
urine. 

Again, it will be found that many concentrated specimens of urine, when 
first passed and while perfectly clear, will, on slight acidification with acetic 
acid or with a mineral acid, give an immediate precipitate of quadriurates, 
while the same specimen may require hours before any urate deposit separates 
spontaneously. The explanation of this would seem to be that the urine 
originally contained the more soluble biurates, and that these are changed 
immediately upon artificial acidification, or more slowly by interaction with 
phosphates, into less soluble quadriurates. 


But whatever may be the primary form of the urates present, it is 
in any case important to recall the facts discussed on p. 578. The 
reaction between urates and phosphates is a reversible one; with acid- 
phosphates, biurates yield quadriurates; with basic (monohydrogen) 
phosphates, quadriurates yield biurates. With a certain proportion- 
ate mixture of the two types of phosphate the uric acid salts will be 
therefore in equilibrium. 

In many urines this equilibrium between the phosphates and urates 
is established, and the determining reactions described above, therefore, 
cease before all the uric acid is liberated. In others, where the 
proportion of monohydrogen phosphate is at the outside large, the 
equilibrium occurs early, and little or no free uric acid separates. Only 
when the original excess of acid phosphate over basic phosphate reaches 
an adequate value is the whole of the uric acid set free. In other 


1 Roberts, Joc. cit. 
2 Flensburg, Jahresb. ti. d. Fortschr. d. Thier-Chem., Wiesbaden, 1894, Bd. xxiii. 


S, 581, 


- 


URIC ACID. 591 


words, the chief factor which determines the precipitation of uric acid 
is the degree of acidity of the urine. Roberts has found that two other 
agencies exert an influence over this precipitation—the pigmentation 
of the urine, and its comparative richness or poverty in salines. Other 
things being equal, a specimen which is poor in pigments on the one 
hand, or in neutral salts on the other, will exhibit a special tendency 
to deposit its uric acid in crystals. But while the question of acidity 
affects that stage of the process which consists in the change from 
biurates to quadriurates, the pigmentation and percentage of salts 
affect rather the change from quadriurate to free acid. The urinary 
pigments and the neutral salts inhibit the decomposition of quadri- 
urates by water, 


Fic. 52.—Upper half, ammonium urate. Lower half, sodium urate. 


Upon standing, some specimens of urine deposit urates, not as amorphous 
quadriurates, but as crystallie biurates. Ammonium urate is frequently to be 
seen in the deposit from alkaline urine in the form of roughly dumb-bell-shaped 
masses; and in concentrated specimens sodium urate forms the so-called thorn- 


apple crystals (Fig. 52). 


Isolation of uric acid from the urine—Tf the urine be acidified with 
hydrochloric acid, much of its uric acid separates in pigmented crystals, 
which tend to adhere to the sides of the vessel. These can be easily 
identified by the microscope. But for the purpose of applying’ the 
characteristic tests, a supply of uric acid may be more conveniently and 
quickly obtained by adding crystals of ammonium chloride to the 
urine till near saturation, and then a few drops of strong ammonia. 
The precipitate which falls is at once filtered off, washed from the filter 
with a little hot water, and warmed with a few drops of hydrochloric 


592 THE CHEMISTRY OR THE CRINE. 


acid. After cooling, the crystals of uric acid which fall may be washed 
by decantation. 

Tests and reactions—(a) The murexide test—If a small quantity of 
uric acid be placed upon a watch glass, a little strong nitric acid, or a 
few drops of bromine water added, and the whole taken to dryness upon 
the water-bath, an orange-red residue is obtained which, if touched with 
a drop of ammonia, yields a fine purple colour. If a minute quantity of 
sodic-hydrate solution be subsequently added, the purple colour changes 
to blue; while, on warming the alkaline solution, all colour is discharged. 
The water-bath should always be used for evaporation in applying this test, 
and if the watch glass be allowed to remain on the bath for a considerable 
time, after evaporation is complete, a red colour will develop without 
further treatment, and the residue will dissolve to a purple solution in 
distilled water. This is the most delicate method of applying the test. 


The residue left by the action of the nitric acid or bromine water consists 
of various oxidation products of uric acid, amongst which is alloxantin 
(C,H;N,O, or C,H,N,O,.H,O). This substance yields, with ammonia, 
ammonium purpurate, which is the purple product of the test. 


(b) Ii uric acid be dissolved in a little caustic soda, a few drops of 
Fehling’s solution added, and the solution boiled, a yellowish precipitate 
of cuprous oxide is obtained (cf. p. 608). 

(c) An alkaline solution of uric acid gives, on the addition of a few 
drops of a solution of phosphomolybdie acid, a dark blue precipitate with 
a metallic lustre, which under the microscope is seen to consist of small 
six-sided prisms.’ 


Estimation.—The methods now used for the estimation of uric acid depend 
either upon the insolubility of its silver compound in ammoniacal solutions, or 
upon the depression in solubility which ammonium urate undergoes in the 
presence of other ammonium salts: Of the silver processes the Salkowski-? 
Ludwig? method is the most accurate. In this the phosphates of the urine are 
first precipitated by the addition of an ammoniacal solution of magnesium 
chloride, containing ammonium chloride (magnesia mixture). Without filter- 
ing off the phosphates, a solution of ammoniacal silver nitrate is next added, 
which gives a further precipitate of silver-magnesium urate. After standing, 
the mixed precipitates are filtered off, washed, and treated with a solution of 
potassium-hydrogen sulphide, which decomposes the silver compound, forming 
silver sulphide and potassium urate. The black precipitate of the former is 
filtered off, and the uric acid liberated in the filtrate by the addition of hydro- 
chloric acid. It is finally separated by filtration and weighed. 

The writer* has modified the previous methods employed for the separation 
of uric acid as ammonium urate in such a way that the precipitation is absol- 
utely complete, and the results are as accurate as those of the foregoing method, 
while much more easy to obtain.® The urine (100 c.c.) is saturated with 
chloride of ammonium, and allowed to stand for two hours, when the resulting 
ammonium urate precipitate is filtered off, washed from the filter with hot 
water, and the uric acid liberated by warming with hydrochloric acid. 
After standing it is filtered off, washed, and weighed. 

1 Offer, Centralbl. f. Physiol., Leipzig u. Wien, 1894, Bd. viii. S. 801. 

2 Arch. f. d. ges. Physiol., Bonn, 1872, Bd. v. S. 210. 

3 Zischr. f. anal. Chem., Wiesbaden, 1885, Bd. xxiv. S. 637. 

4 Hopkins, Journ. Path. and Bacteriol., Edin. and London, 1893, vol. i. p. 450. 

5 Of. v. Jaksch, ‘‘ Klinische Diagnostik,” 1896, 4th edition, S. 428, 431; Ritter, 
apes eee Chem., Strasburg, 1895, Bd. xxi. S. 288: Luff, Goulstonian Lectures, 
1897, Lect. 1. 


URIC ACID. 593 


Variations in the amount.—(a) The relation to urea; the effects 
of diet—Variations in the quantity of uric acid have been considered 
from two different poimts of view. By some, these variations have 
been expressed always in relation to the quantity of urea excreted 
simultaneously. Such observers have felt that an increase or decrease 
in uric acid, which merely accompanies a corresponding change in the 
general nitrogenous metabolism, is of less physiological significance than 
a variation which occurs independently of (or out “of proportion to) the 
latter; and since the urea excretion is a measure of this general 
metabolism, the uric has been, by such writers, referred to the urea 
output as a standard. Other and more recent authorities, seeing the 
origin of uric acid in an entirely distinct series of events within the 
body, and observing that the urea : uric acid ratio has no stable 
value, have recommended the entire neglect of this relation, prefer- 
ring to express the uric acid output always in terms of its absolute 
amount. 

An attempt has been made to show that urea and uric acid are 
always produced in the body, so as to bear a constant and definite ratio 
to each other, and that any alterations in this ratio indicate either a 
retention of uric acid on the one hand, or a sweeping out of previously 
retained acid on the other! That this position cannot be maintained in 
its entirety is quite certain. Consideration of the effect of varying diet 
alone gives sufficient evidence against it. If the two analyses by Bunge, 
given in an early section of this article, be examined, we see that upon a 
diet of bread, not ‘only is the absolute amount of uric acid less than upon 
a diet of beef, but also that the relation to urea is also strikingly less. 
On bread the ratio is 1 to 81, on beef it is 1 to 48. Similar results are 
obtained, as the writer has found, if the experiments are continued for 
many days. Ifthe two substances were always produced in constant ratio 
we should have to conclude that a bread diet produces a continuous 
storing up of uric acid in the body; and for this conclusion there is 
certainly no evidence. 

Again, if we consider the effect of varying the quantity of the 
ingested food—its composition being maintained uniform—we find that 
on the whole the uric-acid excretion is less affected by such variations 
than is the urea, so that we change the value of the ratio merely by 
altering the amount of food taken. 

It is therefore impossible to look upon the ratio which uric acid 
bears to urea as an independent physiological constant, or to conclude 
that even wide variations in its value are necessarily pathological. 

But some authorities go further than to say that the uric acid 
output is more stable than “that of the ure a, claiming, indeed, that it is 
quite unaffected by the absorption of the ordinar y proteids of diet—the 
albumins and globulins with their derivatives. If this be a fact, and 
the production of the acid is independent of variations in these main 
nitrogenous constituents of food, we ought certainly, in studying the 
quantity in the urine, to neglect its ratio to urea altogether. This ratio 
will then be little more, under ordinary circumstances, than an expression 
for the urea variations, measured from the more stable uric acid output, 
so to speak, as a base line; while, if we are studying the effect of special 
factors upon uric acid production, reference to the urea will be un- 
necessary and misleading. 

1 Haig, ‘‘ Uric Acid in Disease.” 
VOL. 1.—38 


594 THE CHEMISTRY OF THE URINE. 


Salkowski, in 1889,! was among the first to give prominence to this 
view, but the experiments upon which he then based his opinion were not 
wholly calculated to decide as to what is the effect, if any, of the ingestion 
of ordinary proteids. They were in the main those of Hirschfeld,? but 
the experiments of this investigator were directed to a broader question 
than that of uric acid excretion, and the diet for the purposes of his 
research was made entirely abnormal, so that definite conclusions on the 
point we are discussing cannot be fairly drawn from them. In the experi- 
ments of Horbaczewski and Camerer,? undertaken with the object of ascer- 
taining the effect of glycerin, carbohydrates, and fat, respectively, on uric 
acid excretion, there were certain “normal periods,” in which a standard 
mixed diet was taken alone. The fact that the diet was carefully maintained 
at a uniform level makes these very careful experiments more or less unavailable 
for our purpose. Nevertheless, during one of these control periods, which 
lasted for many days, the urea excreted fluctuated somewhat widely, pre- 
sumably from varying degrees of proteid absorption. Of this period the 
author says: “The uric acid eliminated went hand in hand with the nitrogen 
excretion. In general, the more the total nitrogen present the more the uric 
acid found.” 

There are but few experiments recorded which bear properly on our 
problem, fundamental though it be; that is to say, experiments where the 
uric acid and urea (or total nitrogen) have been estimated from day to day 
by reliable processes ; while the quantity, but not the quality, of the proteids 
ingested has been made to vary widely. Schiiltze + found the uric acid rise 
with increase of flesh diet. Hester and Smith® found it raised when the 
ingestion of proteids was increased, though it was somewhat less affected than 
the urea. I myself have repeatedly observed a rise to follow an increase in 
the diet where the composition of this has been carefully maintained constant. 

But these observations are open to one criticism. Whatever the effect of 
globulins or albumins, there appears to be no doubt that ingestion of 
nucleo-proteids increases the excretion of uric acid ; calves’ thymus, with its 
abundant nuclein, has been largely used to test this point. Umber® and 
Weintraud’ have found that with thymus the excretion of uric acid may 
amount to double that of the same individual upon ordinary proteid (muscle) 
diet of equal nitrogenous value. 

Is, then, the smaller increase found when ordinary proteid diet is taken, 
merely due to any nuclein present and not to the absorption of the ordinary 
proteids? We shall be able to add the last word to this discussion 
immediately. 

If the effect of an zsolated meal of ordinary mixed diet be studied, it 
is found that an increase in the excretion of uric acid occurs very rapidly 
after the food is taken. According to Marés® the maximum hourly exeretion 
occurs at the fifth hour after the meal; four hours before the urea reaches 
its maximum. This observer held, therefore, that it was not derived directly 
from the ingested proteid, but from cellular activity during digestion. 
Horbaczewski confirmed this result, and believed that it was due to a digestive 
leucocytosis (vide article, “ Metabolism”), with its consequent liberation of 
nucleins in the body. But Camerer® has recently found that this rise of 

1 Virchow’s Archiv, 1889, Bd. exvii. S. 572 ; comments on a paper by Spilker. 

2 Ibid., Bd. exiv. S. 301. 

3 Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1886, Bd. xeviii. Abth. 3, 8. 301. 

4 Arch. f. d. ges. Physiol., Bonn, 1889, Bd. xy. S. 427. 

5 New York Med. Journ., 1892, p. 38. 

8 Ztschr. f. klin. Med., Berlin, 1896, Bd. xxix. S. 174. 

7 Berl. klin. Wehnschr., 1895, S. 407. 

8 Centralbl. f. d. med. Wissensch., Berlin, 1888, S. 2. 


° Ztschr. f. Biol., Miinchen, 1896, Bd. xxxiii. S. 136; also Weintraud, Chem. Centr.- 
Bl., Leipzig, 1895, Bad. ii. S. 234. 


URIC ACID. 595 


uric acid after a meal is by no means marked, unless the food taken contains 
nuclein. Ona diet composed, for instance, of egg albumin, the rise was very 
small, while during the digestion of non-nitrogenous diet the output of uric 
acid was even diminished. Camerer holds, therefore, that digestive leuco- 
cytosis cannot be the cause of post-prandial increase, but only the actual 
ingestion of nucleins, and his results would suggest that we must answer the 
question in the previous paragraph in the affirmative, and recognise that 
the excretion of uric acid is not increased by the ingestion of ordinary 
proteids. 

If this be confirmed, we must for the future attach no importance te the 
urea : uric acid ratio; and when we wish to eliminate mere dietetic effects 
from our study of other specific variations in the urinary uric acid (when, for 
instance, we are endeavouring to ascertain if retention is occurring in disease, 
or whether a certain drug is promoting elimination), we must do this by 
controlling the ingestion of nucleins during the experiments. 


It should be understood, however, that in spite of much labour spent 
upon the problem, our knowledge of the relation of urinary uric acid to 
diet is scarcely yet upon a firm foundation, and contradictory statements 
will be found in the literature. Future investigators may have to face 
yet another difficulty, if it be true, as Weintraud? affirms, that a true 
excretion of uric acid may occur through the walls of the intestine. 

One fact is abundantly certain—that great individual differences 
exist in uric acid excretion. In spite of all that has been said above, it 
is found that, with the ordinary regularity of habits and diet customary 
in civilised life, the uric acid output (when the whole twenty-four hours’ 
excretion is dealt with), and even its relation to urea, will remain fairly 
constant in any given individual; whereas, when different individuals 
are compared, much greater differences are seen. Before we can say 
with certainty what constitutes a pathological or exceptional condition 
in any case, we must know the normal behaviour of the particular 
organisation in question (Salkowsk1i). 

The ratio borne to urea may vary in different healthy individuals 
~from 1:25 to 1:50; the proportion most commonly found being from 
about 1:35 or 1:40. 

(6) Variations apart from diet—It is a well-established fact that 
in newly-born children the uric acid excretion bears a high proportion 
to the body weight, and also to the other nitrogenous constituents of 
the urine. In the first few days of hfe 7-8 per cent. of the urmary 
nitrogen may be in the form of uric acid.? 

The absolute amount is increased by excessive exercise and 
diminished by rest. With regard to drugs, the action of alkalies is 
still disputed. It is possible that an isolated dose may temporarily 
accelerate excretion ; but, according to Spilker and Salkowski,? continued 
administration diminishes it. There is certainly no foundation for the 
statements of Haig, that the excretion of uric acid varies inversely as 
the acidity of the urine.t Salicylates undoubtedly increase the amount 
in the urine. Pilocarpine produces an increase, possibly from the 
leucocytosis which follows its use. Pathologically, there is increase in 


1 Chem. Centr.-Bl., Leipzig, 1895, Bd. i. S. 310. 

2 Hofmeier, Virchow’s Archiv, 1882, Bd. Ixxxix. S. 493. 

3 Tbid., 1889, Bd. exvii. S. 570. 

4 Cf. Herringham and Davies, also Herringham and Groves, Journ. Physiol., Cambridge 
and London, 1891, vol. xii. pp. 475 and 478. 


596 THE CHEMISTRY OF THE URINE. 


conditions of leukemia, and this may be said to be the only well- 
established fact as to the effect of disease on uric acid excretion. In 
gout, although the urate deposits form so prominent a factor, the question 
of the amount excreted in the urine is still unsettled. In this country, 
at any rate, many cases occur in which, as originally observed by Sir A. 
Garrod, the excretion during the chronic condition is oreatly diminished, 
whereas, in relation to the acute attack, increased elimination may 
occur! Pyrexia alone does not produce any marked increase; but 
in certain specific fevers with a definite crisis, a large temporary 
increase may occur, depending, according to Horbaczewski, upon the 
associated leucocytosis. 

Uric acid is one of the commonest constituents of urinary calculi. 

(e) The xanthin bases.—Several members of this chemical group 
are found in urine, in variable but always small amount. Yanthin 
itself was discovered by Marcet in 1819 as a constituent of a urimary 
calculus, and its presence in urine was first demonstrated by Strecker in 
1857. In addition to xanthin, the’ followmg members of the group 
may be present — heteroxanthin, paracanthin, hypoxanthin (sarkin), 
guanin, adenin, and carnan. 

All these substances are closely related to each other and to uric 
acid; and the chemical group to which they belong also contains 
certain important vegetable bases. 

The relation of zanthin to uric acid is best understood by a com- 
parison of the structural formule; our knowledge of the constitution of 
the base being due to E. Fischer. 


NH—C—NH NH—C = 
lototh ame ee Met "Sco 
CO C—NH CO C—NH 
| | | | 
NH—CO NH—CH 
(uric acid) (xanthin) 


Xanthin contains one atom less oxygen than uric acid, while hypo- 
zanthin contains one less than xanthin. 


C.H,N,0, C.H,N,O, C.H,N,O 


(uric acid) (xanthin) (hypoxanthin) 


In the laboratory means have not been found to pass from one of 
these three compounds to another by oxidation or reduction ; but in the 
body the steps involving oxidation can certainly occur. 

Heteroxanthin and “paraxanthin are homologues of xanthin, the 
former being its methyl- and the latter its dimethyl-derivative ; 
paraxanthin is therefore an isomer of the vegetable bases, theobromin 
and theophyllin. 

Guanin in an imido-xanthin; that is to say, it is xanthin with an 
oyygen atom replaced by an NH group; and adenin bears the same 
relation to hypoxanthin. 


C.H,N,0.0 C,H,NONH C.H.N,0 6,H,N,NH 


(xanthin) (guanin) (hypoxanthin) (adenin) 


Uric acid and the xanthin bases are grouped together by recent 
1 Cf. Fawcett, Guy’s Hosp. Rep., London, 1895 ; Luff, Goulstonian Lectures, Lect. i. 


THE XANTHIN BASES. 597 


German writers ! under the term, “alloxuric substances,” a name meant 
to show their relation on the one hand to alloxan,? and on the other to 
urea ; the bases themselves may be designated the “alloxuric bases.” 

The amount of the xanthin bases in the urine has been generally 
understated until lately ; they amount collectively to something like 
one-tenth of the uric acid present ; that is to say, an average of 0:1 to 0:07 
grm. of the combined bases is excreted per diem (Camerer, Salkowsk1). 
Of xanthin itself some 0°02 to 0:03 grm. is found, upon a mixed 
diet. 

General properties—That the xanthin compounds, unlike uric acid, 
are basic in character, is probably due to the fact that the CO group is 
absent from the central carbon chain. (Cf. graphic formule above.) 

Their basicity is, however, very feeble, and many of their compounds 
with acids are decomposed by water—just as is the “sulphate” of uric 
acid; while, on the other hand, they are all capable of forming metallic 
derivatives and compounds with other bases. They contrast sharply 
with uric acid in their easy solubility in mineral acids. In ammonia 
they are also soluble (with the exception of guanin). Xanthin itself 
dissolves to a very slight extent in water, but the other bases are more 
soluble. 

They are precipitated from urine—(1) By the addition of phospho- 
tungstic or phosphomolybdic acids in acid solution ; (2) by silver nitrate 
in ammoniacal solution; and (3) by copper salts; especially in the 
presence of thiosulphates. When precipitated by any of these methods, 
they are accompanied out of solution by uric acid (vide infra). 


Isolation and estimation.—It is beyond the scope of this article to describe 
in detail the separation of the xanthin bases individually. Very large quanti- 
ties of urine (100 litres and upwards) are required for the purpose. If the 
precipitate obtained by adding ammonia, and afterwards ammoniacal nitrate 
of silver solution, be decomposed by sulphuretted hydrogen, and the filtrate 
from the silver sulphide acidified with hydrochloric acid, concentrated, and 
allowed to stand, the uric acid ecrystallises out. This being filtered off, the 
liquid is again made alkaline with ammonia and the bases again precipitated 
with silver nitrate. The varying solubility of the silver compounds so 
obtained in nitric acid permits of a preliminary fractionation of the bases ; 
and, when liberated from combination with silver, their diverse solubilities in 
water and other media yield methods for their final separation from each 
other. 

If urine (100 c.c.) be heated to boiling, and precipitated with a mixed 
solution of copper sulphate and sodium thiosulphate, some chloride of barium 
being afterwards added, a precipitate is obtained which contains all the uric 
acid and xanthin bases, but no other nitrogenous constituent (Kriiger and 
Wulff). By estimating the nitrogen in this precipitate by means of Kjeldahl’s 
process, we obtain a measure of what may be called the “ alloxuric nitrogen,” 
an important urinary constant. If a separate estimation of the uric acid be 
made, the nitrogen proper to this may be deducted from the “alloxuric 
nitrogen,” and we obtain a value for the “nitrogen of the bases.” Such a 


1 Kriiger and Wulff, Ztschr. f. physiol. Chem., Strassburg, 1896, Bd. xx. S. 176. 
NH—CO 


2Alloxan, CO CO/f isan oxidation product of uric acid. The xanthin bases and uric 
[race | 
NH—CO 


acid will all be seen to contain the urea residue and the three-carbon chain, which together 
comprise the so-called ‘‘ alloxan ring.” 


598 THE CHEMISTRY OF THE ORINE. 


procedure is our most convenient method for following the variations in the 
excretion of the xanthin group.! 


Tests—Xanthin and its two homologues, and also carnin, but not the 
other bases, give Weidel’s reaction. This is almost identical with the 
murexide test described for uric acid, but chlorine water is used instead 
of nitric acid. The bases resist oxidation with nitric acid much more 
fully than does uric acid, but, in the presence of a small quantity of a 
chloride, xanthin will give the ordimary murexide reaction. Very 
characteristic of xanthin and hypoxanthin are the crystalline precipi- 
tates which they yield with silver nitrate in the presence of nitric 
acid, 

Variations in the amount of the urinary xanthin bases closely follow 
those of uric acid, and for the most part depend upon the same 
influences. The bases, however, are apt to vary even more widely. 
According to Camerer? they are greatly increased by certain forms of 
vegetable food; thus, in one experiment, on a flesh diet the nitrogen 
present as these bases was only 0:1 per cent. of the total nitrogen ; 
while, when green vegetables formed the chief ingredient of the food, it 
was 0°6 per cent. They are increased by diet rich in nucleins3 and 
pathologically their amount is greatly raised in some forms of leukeemia. 

(f) Creatinin.—This base is chemically distinct from the alloxuric 
compounds, in that its molecule contains neither the alloxan ring nor 
the urea residues which are characteristic of these. Nevertheless, on 
hydrolysis, it easily yields urea and an amido-acid (methylglycine). It 
is the anhydride of creatin, which is itself methylglycocyamin. 


NH, /NH 
CINE) CONT 
\N(CH,)—CH,—COOH NOH! _CH,—CO 


(creatin) (creatinin) 


Whether creatin itself is ever a urinary constituent is somewhat 
uncertain. It has been stated to occur when the urine is excreted in 
alkaline condition, but the quantity is, in any case, very small. So 
easily are the two substances converted the one into the other, that care 
is requisite in the isolation of either. When creatin stands in acid solu- 
tion, it tends to change into its anhydride, while creatinin in alkaline 
solution suffers the inverse change. 

G. S. Johnson® has found, however, that urinary creatinin is not 
identical, but isomeric, with that obtained artificially from creatin (e.g. 
by the action of acids), and distinct from the creatinin found in small 
quantity in muscles. 

The creatinin of urine was first isolated by Liebig. It is present on 
an average to the extent of about 1:0 grm. in the excretion of twenty- 
four hours, when a mixed diet is taken. 

Properties—In its compounds creatinin exhibits well-marked basic 
tendencies, and it can liberate ammonia from ammonium salts on boil- 
ing; but, according to Salkowski, solutions of the pure substance react 


1 For details see Kriiger and Wulff, loc. cit. supra. 

* Zischr. f. Biol., Miinchen, 1891, Bd. xxviii. S. 72. 

>’ Weintraud, Zoc. cit. 

4 Hoffemann, Virchow’s Archiv, 1869, Bd. xlviii. S. 358. 
> Proc, Roy. "Soc. London, 1892, vol. 1. p. 287. 


CREATININ. 599 


neutral to litmus. The crystalline form of the base varies with the 
method of preparation (Johnson). As ordinarily obtained, it exists as 
colourless monoclinic prisms, which are often imperfectly formed, and 
appear of whetstone shape (Fig. 53). It dissolves in about twelve parts 
of cold water, but requires a hundred parts of alcohol to dissolve it at 
ordinary temperatures. In ether it is almost insoluble. Creatinin 
reduces alkaline copper solutions (ef. p. 608). It forms characteristic 
erystalline salts with the mineral acids, aqueous solutions of which react 
acid to litmus. With certain salts of the heavy metals it forms crystal- 
line molecular compounds, two of which are of practical importance. 

Creatinin zine-chloride—(C,H,N,0),ZnCl,—separates as a precipi- 
tate, consisting of stellate clusters of acicular crystals, when a concen- 
trated neutral solution of chloride of zine is added to an aqueous or 
alcoholic solution of the base. The compound is soluble in hot water, 
in mineral acids, and in alkalies; but insoluble in alcohol, and very 
shghtly soluble in cold water. 

Creatinin mercuric-chloride, a complex compound of the formula 
4(C,H,N,O.HCl.Hg0),3HgCl,. This is precipitated in colourless, glassy, 
spherular masses, when sodium acetate and mercuric chloride are added to 
creatinin solutions. The base is also precipitated, even from very dilute 
solutions, by the addition of phosphotungstic, phosphomolybdie, or picric 
acids. 


Isolation and estimation.—Neubauer separated creatinin from the urine by 
means of its combination with zine chloride, this salt being added to an 
alcoholic extract of the evaporated urine. A more convenient method is to 
treat the urine direct with a little sodium acetate, and then with one-fourth 
its volume of saturated mercuric-chloride solution. The precipitate which 
first falls is at once filtered off; it contains uric acid and other constituents, 
but not creatinin. The filtrate from this rapidly begins to deposit the mer- 
cury compound described above, and in forty-eight hours precipitation is com- 
plete (G. S. Johnson). The base itself is prepared by decomposing this 
precipitate with sulphuretted hydrogen, and by treating the creatinin-hydro- 
chloride, so obtained, with hydrate of lead.1_ To determine the quantity, the 
mercury precipitate may itself be weighed, and the percentage of creatinin 
calculated from this.” 


Tests.—If a solution of creatinin be treated with a small quantity of 
very dilute sodium nitroprusside solution, and subsequently with weak 
caustic alkali, a rich, ruby-red colour is produced, which afterwards 
changes to yellow (Weyl’s reaction). If acetic acid be now added in 
excess, and heat applied, the solution becomes green, and then blue, 
and finally a precipitate of Prussian blue is formed. Acetone (p. 616) 
gives an analogous reaction, but behaves differently after the addition of 
the acetic acid. Many specimens of urine will give Weyl’s test direct. 

Jaffé’s test is an application of the fact that creatinin gives, with 
picric acid and caustic alkali, an intense red colour, even in the cold. 

The variations in the urinary creatinin generally follow very closely 
those of the urea, but there can be no doubt that its quantity depends 
largely on the amount of creatin taken with the food. Its physiological 
relations are discussed elsewhere. Pathologically, it is increased in most 
febrile conditions, and in diabetes. It has been stated to diminish in 


1Jn this process all the operations are carried out in the cold ; by this means the true 
urinary creatinin is obtained. Heat produces isomeric change. 
2 Cf., however, Allen, ‘‘Chemistry of Urine,” pp. 156 and 159, 


600 THE CHEMISTRY OF THE URINE. 


progressive muscular atrophy, and in pseudo-hypertrophic paralysis. 
According to Senator, no increase is produced by the paroxysms of 
tetanus—a fact which is of interest as bearing on the relation of 
muscular activity to the urinary creatinin. 

(g) Hippuric acid. — Hippuric acid is benzamido- acetic acid, or 
benzoylelycin, C,H,.CO.NH.CH,.COOH ; in other words, it is a con- 
densation product of benzoic and amido-acetic acids, in the formation 
of which the hydroxyl group of the former is eliminated as water, 
with an atom of hydrogen from the amido group of the latter. But 


Fic. 53.—A. Creatinin ; B. Hippuric acid. 


the simplest artificial synthesis is obtained when monochlor-acetic acid 
is heated with benzamide. 


C,H,CO.NH,+CH,Cl.COOH = (C,H,,CO)NH.CH,.COOH+HCI 


In most mammals the synthesis by dehydrolysis occurs in the kidney ; 
hippuric acid appearing in the urine, whenever benzoic acid, or pre- 
cursors of benzoic acid, are taken by the mouth. The excretion of 
hippuric acid is, indeed, tmainly dependent upon the relative richness of 
the diet in such precursors of benzoic acid. 

It is not necessary that benzoic acid should itself be ingested. A 
benzene derivative containing a single “side-chain” is nearly always 
oxidised in the body to benzoic acid. Such substances, therefore, as 
toluene, C,H;.CH,; cinnamie acid, C,H,CH.OH.COOH ; or phenyl- 
propionie acid, C,H,CH,.CH,.COOH, all give rise to an excretion of 
hippuric acid when they are taken by the mouth. Aromatic compounds 
of this type are abundantly present in some forms of vegetable food, as 


HIPPURIC ACID. 601 


in many fruits and in the cortical parts of most plants. Vegetable food 
greatly increases, therefore, the excretion of hippuric acid. 

But the vegetable aromatic compounds are not the sole source of the 
urinary hippuric acid. In the decomposition of proteids, which occurs 
in the bowel, aromatic residues split off. Precursors of benzoic acid 
(mainly, perhaps, phenylpropionic acid) are thus formed, and after 
oxidation they appear in the urine as hippuric acid. The metabolism 
of the tissue proteids themselves, moreover, may yield precursors of the 
same kind, so that even in starvation hippuric acid does not wholly dis- 
appear from the urine. 

This dual origin (from aromatic precursors in the diet chiefly, but 
likewise from proteid metabolism) is found also in the case of the other 
aromatic constituents of the urine (p. 605). 

Upon a mixed diet the exeretion of hippuric acid in human urine 
amounts to about 0-7 grms. per diem; upon a diet rich in fruits it may 
be raised to three or four times this. In herbivora the quantity is much 
larger; the urine of cattle, for instance, often contains as much as 
2 per cent., though, as might be expected, that of sucking calves only 
contains small amounts. 

Properties.—It forms four-sided prismatic crystals ending in two or 
four facets, and often grouped in clumps (Fig. 5 3), of which the melting 
point is about 187°. It is but slightly soluble in cold water or alcohol ; 
but both these solvents dissolve it easily when hot. It is soluble in 
acetic ether, but not so in most other organic liquids. If heated to 240° 
it decomposes, benzoic acid subliming out and a reddish residue being left 
behind: When first heated at this temperature a hay-like odour is given 
off, which is succeeded by that of prussic acid. When boiled with strong 
hydrochloric acid it splits up into its components, benzoic and amido- 
acetic acids. The growth of the Micrococcus wrew can bring about this 
decomposition, so that stale specimens of urine often contain benzoic in 
place of hippuric acid. Taken to dryness with nitric acid, it yields an 
odour of nitrobenzene. 

Solutions of hippuric acid react acid to homas, and even when very 
dilute they impart a violet colour to congo-red. By the use of the latter 
indicator Briicke proved the absence of the free acid from the urine. It 
is present always as salts. It forms salts with bases, but does not 
combine with acids. Its iron compound is insoluble in hot water, and 
may be employed in separating the acid from its solutions. 


Isolation and estimation.—The method of Bunge and Schmiedeberg ! 
consists in making an alcoholic extract of the urinary solids, evaporating off 
the spirit, dissolving the residue in water, and, after acidifying with hydro- 
chlorie acid, shaking up repeatedly with successive quantities of acetic-ether. 
On evaporating the latter, impure crystals of the acid are obtained, the 
impurities being removed by treatment with petroleum-ether, in which 
hippuric acid is insoluble. 


Tests—The substance is recognised by its crystalline form, by its 
melting point, by its behaviour on heating, and by the formation of its 
insoluble iron compound when neutral ferric chloride is added to its 
solutions. 

In addition to hippuric acid, minute quantities of its homologue 
phenaceturic acid (phenylacetylglycin), C,H,.CH,CO—NH.CH,.COOH, 

1 Arch. f. exper. Path. u. Pharmakol., Leipzig, Bd. vi. S. 235. 


602 THE CHEMISTRY OF THE URINE. 


are occasionally found in human urine. Its origin and significance are 
analogous to those of the more abundant substance. 

When benzoic acid or its precursors are administered to birds, they 
are excreted as ornithuric acid, which is an analogous conjugated com- 
pound of benzoic acid with diamidovalerianic acid. 

(h) Amido-acids.—These, in simple unconjugated form, are seldom 
found in normal urine. Under certain pathological conditions leucine 
and tyrosine appear in considerable quantities. The elimination of these 
substances is especially associated with conditions in which a rapid 
destruction of the hepatic tissue has occurred; thus they are found in 
acute yellow atrophy of the liver, and, to a less extent, in phosphorus- 
poisoning. 

When these amido-acids are given by the mouth in moderate 
quantity, and under conditions of normal health, their nitrogen is 
excreted wholly in the form of urea. If, however, tyrosine be adminis- 
tered in very large amounts, it may be excreted in part as tyrosine- 
hydantoin, in which it exists as a conjugate compound with urea; and 
at the same time other aromatic constituents of the urme are increased 
in quantity by derivation from its aromatic nucleus. Only when the 
normal hepatic functions are in abeyance does the unaltered amido-acid 
itself appear.? 

When present in urine, leucine and tyrosine are usually found 
together. If in large quantity, they may, though very rarely, form 
a deposit; at other times they may be seen under the microscope 
when a drop of the urine is evaporated. 


In general, however, they must be 
separated by special means. The 
leucine may be dissolved, by means of 
hot alcohol, from the residue obtained 
by evaporating the urine, and when 
the alcoholic extract cools it separates 
as a greasy mass, which under the 
microscope will be seen to consist of 
minute spheroids with concentric mark- 
ings interrupting a radiated structure. 
To demonstrate the presence of tyrosine, 
the urine is first precipitated with 
basic acetate of lead, the filtrate from 
the lead precipitate treated with sul- 
phuretted hydrogen and again filtered. 

Fic. 54,—Leucine and Tyrosine. On thorough concentration and cool- 

ing of the lead-free filtrate, the tyrosine 

separates out in characteristic acicular prisms, which are mostly combined 
into sheaves or stars (Fig. 54). 


Cystine * is another amido-acid, but it is at the same time a sulphur- 
containing substance, differing in its metabolic significance from leucine 
and tyrosine. 


1 Jafié, Zischr. f. physiol. Chem., Strassburg, 1883, Bd. vii. S. 306. 

* According to the recent observations of Ulrich, leucine and tyrosine are always to be 
found in normal urine, though in small quantity, Centralbl. f. Physiol., Leipzig u. Wien, 
1897, Bd. xi. S. 12. 

3 Cf. Baumann, Ztschr. f. physiol. Chem., Strassburg, 1884, Bd. viii. S. 299; also 
Brensinger, zbid., 1892, Bd. xvi. 8. 552. ‘ 


PROTEIDS. 603 


It is a sulphur derivative of an amidolactic-acid, and has the 
formula : 


CH, CH, 
| | 

NHL 36" <6--.0 -NE, 
| | 
COOH COOH 


It may appear in small quantity im certain diseases, but is generally 
a product of peculiar disordered metabolism, which is found to be char- 
acteristic of certain families. Members of such families may excrete 
habitually from 0°5 to 1 grm. daily. It sometimes separates as a crystal- 
line deposit from the urine, and occasionally forms calculi in the urinary 
tract. 

Physiologically it is of interest, in that cystine or substances allied to 
it are probably the precursors of certain of the normal sulphur compounds 
of the urine (p. 632).4 

Its crystals are very characteristic, being usually in the form of 
hexagonal plates (Fig. 55); more rarely it appears in rhombohedral 
form. Urine which contains it will, if heated with caustic potash and 
plumbie acetate, give a black precipitate of lead sulphide. 


PROTEIDS. 


Normal urine contains but traces of substances belonging or allied 
to the proteid group. But minute quantities of a nucleo-proteid derived 
from the cells of the urimary passages 
are seldom or never absent. In the 
majority of cases the amount of this 
is so small that it is difficult directly 
to demonstrate its presence. The 
flocculent cloud which generally 
separates on standing, even from the 
clearest urine, by no means always 
contains any isolated proteid, but may 
consist entirely of intact epithelium 
cells. But the nucleo-proteid may 
be detected by suitable tests in the 
precipitate which falls when large 
quantities of normal urine are mixed 
with alcohol. 

The nucleo-proteid may, on the Fic. 55.—Cystine. 
other hand, so far increase in con- 
ditions of apparent health, that the urine will react to Heller’s test 
(vide infra). Thus Flensburg? found, on examining the urine of 1252 
healthy persons, that 97 of these gave a reaction with nitric acid, which 
could be shown to be due to a nucleo-proteid. 

In such cases, and in others where the increase is greater and due to 
inflammatory changes in the urinary tract, the nucleo-proteid may be 
precipitated by the addition to the urime of acetic acid in the cold; 
especially if the fluid be first diluted to eliminate the solvent action of 


1 Goldmann and Baumann, zbid., 1888, Bd. xii. S. 254. 
* Skandin. Arch. f. Physiol., Leipzig, 1893, Bd. iv. S. 410. 


604 THE CHEMISTRY OF-THE GRINE. 


the salts present, or, better still, if the salts be first reduced by dialysis. 
In some pathological conditions, and especially in cystitis, the amount may 
be so greatly increased that it separates as a viscid gelatinous precipitate. 
The mucoid appearance of the urinary nucleo-proteid led to its being long 
looked upon as mucin; but it does not yield a reducing substance on 
hydrolysis, while, on the other hand, it is rich in phosphorus. Nevertheless, 
recent researches made upon large quantities of urine indicate that the 
precipitate given by acetic acid contains small quantities of ordinary 
mucin, OY a phosphor us-free mucoid, as well as the nucleo-proteid.t 

Apart from increase due to inflammatory conditions of the excretory 
tract, nucleo-proteid is said to be increased when the blood is excep- 
tionally rich in leucocytes (leukeemia).? 

The question as to whether or not normal urine contains serwm albumin 
or serwm globulin offers a problem of the same order as that of physio- 
logical glycosuria, fully discussed on p. 608. The matter is, however, of 
less i importance physiologically than is the latter question, as, although the 
evidence to hand points to the fact that if sufficient urine is employed these 
proteids may nearly always be separated in minimal traces, it by no means 
follows that they form part of the true excretion, for they may arise 

rather, like the nucleo-albumin, from the surface of the urinary tract. 

As to the cases when, in apparent health, there is such an increase of 
these proteids that their presence may be shown by the direct applica- 
tion of ordinary tests, we are met with the difficulty of having to define 
what is meant by “ normal” urine. Such quantities may be present, 
for instance, after exceptionally severe exercise, as in the urine of soldiers 
after pr olonged marching (Leube, C hateaubur 2); but it is not certain 
that the excretory mechanism is here working physiologically. 


When, as the effect of disease, the renal epithelium has undergone degenerat- 
ive changes, the presence of albumin in the urine is a common phenomenon ; 
one of the most familiar in pathology. Albuminuria may arise, too, from such 
alterations in the constitution of the blood as upset its normal relations to the 
renal cells; this may be observed in anemia, and as the effect of specific 
poisons. Again, it may follow disturbances of blood pressure in the renal 
vessels, even though these be unassociated with obvious changes in the 
excretory epithelium. Lastly, the albumin due to addition from the excretory 
tract, after the urine has left the kidneys, may pathologically reach a consider- 
able proportion. 

Under pathological conditions, also, the urine may come to contain 
albumoses and peptones. On the one hand, a so-called enterogenous peptonuria 
or albumosuria may occur, when, from degenerative changes in the gastro- 
intestinal walls (e.g. in carcinoma ventriculi or the ulcerative stage of enterica), 
the diffusible proteids reach the blood stream and thereupon are immediately 
eliminated by the kidneys. On the other hand, these substances may reach 
the blood stream from abscesses or other purulent collections where the tissue 
proteids have been hydrolysed by the growth of organisms. Whatever their 
origin (and it is sometimes not so clear as in the above groups of cases), the 
proteoses and peptones no sooner reach the blood than they are found in the 
urine. The older methods of investigation did not clearly distinguish between 
peptones and albumoses in the urine; evidence is now accumulating to show 
that the latter are by far the more common. 


1Cf. Malfatti, Wien. klin. Wehnsehr., 1891, S. 433; also Morner, Skandin. Arch. 
oft Physiol., Leipzig, 1895, S. 437. 

: According to recent ‘observations, the nucleo-proteid of urine is in some cases to be 
identified with Lilienfeld’s “ nucleohiston.” 


AROMATIC SUBSTANCES. 605 


A very large number of fests for the presence of albumin and globulin in 
the urine have been described. We can here refer to two only. 

Heller's test.—A small quantity of strong nitric acid is placed in a test 
tube, and the urine is allowed to flow gently down the side of the tube so that 
it floats upon the surface of the acid without mixing with it. If coagulable 
proteids are present, a dense white ring forms at the junction of the liquids. 
As little as ‘002 per cent. of albumin may be thus detected. The urinary 
nucleo-albumin may react to this test if in sufficient quantity, but the ring 
formed is less dense, and more apt to be formed at some little distance from the 
acid. 

Ferrocyanide test.—A solution of potassic ferrocyanide is first added to the 
urine, and the mixture made acid with acetic acid, when the albumin and 
globulin are precipitated asa flocculent cloud. If the salt be added before the 
acid, nucleo-proteid is not precipitated. 

To separate serum globulin from albumin, the urine is, after neutralisation, 
saturated with magnesium sulphate, which precipitates the former. The 
precipitate may contain certain of the salts of the urine, and heteroalbumose 
if present. The proportion of globulin to albumin may vary greatly, and may 
be quite different from that present in the blood. 

To detect peptones, the urine is saturated with sulphate of ammonium, and, 
after standing, filtered; the biuret test may now be applied to the filtrate, a 
large excess of caustic alkali being used. The ammonium sulphate precipitate 
contains (in addition to ammonium urate) all other proteids present and also 
the urinary mucin. If this precipitate be allowed to stand under alcohol for 
some days, the proteoses are obtained in solution when it is extracted with 
water. The presence of urates must be borne in mind when the ammonium- 
sulphate precipitate is being dealt with, as these yield a coloration with certain 
proteid tests ; and again, may lead to error if ordinary mucin is to be identified 
by its yield of a reducing body on boiling with acids, for uric acid itself 
reduces copper solutions. 


AROMATIC SUBSTANCES. 


In addition to hippuric acid, which, owing to its importance as a 
nitrogenous constituent, we have treated specially, the urine contains 
other substances belonging to the aromatic group; that is to say, 
substances the molecular structure of which contains the benzene 
nucleus. Under normal circumstances each one of these is present in 
very small amount, but collectively they are of importance. For our 
knowledge of their chemistry in the urine we are largely indebted to 
the initiative work of Baumann. 

Like hippuric acid (¢.v.), they are dened in part from the aromatic 
constituents of the food, and they are all increased by a vegetable diet ; 
but also, like hippuric acid, they partly arise from the breakdown of 
proteids. In their derivation from the latter it is possible that tyrosine 
in the bowel is an intermediate stage, as many of them are greatly 
increased when that substance is given by the mouth... We cannot deal 
with these substances in great detail, but the characteristic types 
of compounds in which the aromatic nucleus is found in the urine 
should be noted. They comprise, mainly, simple hydroxyl-substitution 
products of benzene, and carboxyacids related to these.. We shall also 
consider in this section urinary indol and skatol, which are nitrogenous 
aromatic compounds. Most of the substances to be dealt with are 


1 Brieger, Ztschr. f. physiol. Chem., Strassburg, 1878, Bd. ii. S. 256; Wolkow und 
Baumann, ibid, 1891, Bd. xv. S. 228. 


606 THE CHEMISTRY OF THE URINE 


excreted as conjugated sulphates (see p. 631), but the carboxyacids are 
only in part so excreted. Inosit, which belongs to this group chemically, 
has somewhat different physiological relatiqnships to the other aro- 
matics of urine. 

Phenol (C,H;.OH) and kresol (CH,.C,H,.OH).—Traces of carbolic 
acid are present in urine physiologically, but the “ phenol” of the normal 
fluid consists, as a matter of fact, mainly of the homologous ‘resol; and, 
of the isomeric forms of the latter, parakresol is the commonest. The 
properties of this substance, however, closely resemble those of phenol 
itself. The amount of phenol and kresol taken together may be upon a 
mixed diet no more than some 50 mgrms. per diem. If the urine 
be acidified and distilled, the distillate made alkaline, concentrated, and, 
after concentration, neutralised, on the addition of bromine a whitish pre- 
cipitate will appear, due mainly to the formation of the tribromphenols. 

Pyrocatechin (orthodihydroxybenzene) and hydrochinon (para- 
dihydroxybenzene) C,H,(OH),.—Of these two isomeric substances 
the former is a constant constituent of human urme in small 
quantity; the latter is found probably only under exceptional cir- 
cumstances. The former is easily removed from the acidified urine 
by shaking with ether; but its subsequent purification involves a 
lengthy procedure.t It is a white crystalline volatile solid, easily 
soluble in water. It gives a dark green coloration with ferric chloride, 
which, on the addition of ammonia, becomes violet and afterwards 
cherry-red. 

Inosit.—This substance, from its sweet taste, was originally classed 
with the sugars, and was known as “ muscle sugar.” It strictly belongs, 
however, to the group of substances we are considering, as it is by com- 
position hexahydroxybenzene (CH.OH),. It appears in normal urine 
with considerable frequency when polyuria is induced by diuretics or by 
copious drinking. On the other hand, its appearance is not entirely 
dependent upon the flushing of the tissues which such polyuria might 
denote, as extreme polyuria is at other times not associated with 
inosituria. It may occur in diabetes. Galloise found it in five out of 
thirty cases. 

It may be separated from the urine by precipitation with acetate of 
lead. The precipitate is decomposed with hydrogen sulphide, the fluid 
concentrated, and finally precipitated by admixture with a large bulk of 
alcohol. The alcohol precipitate is dissolved in water, the solution 
mixed with an equal bulk of ‘spirit and poured into ether, which pre- 
cipitates the inosit almost pure. 

The substance forms crystals not unlike those of cholesterin. It is 
optically inactive and does not ferment. It is said to yield sarcolactic 
acid by the action of bacteria. 

Of the aromatic carboxyacids the following have been identified 
in human urine:—Parahydroxyphenyl-acetic acid OH.C,H,—CH,.COOH; 
parahydroxyphenyl-propionie acid OH.C,H,—C,H,.COOH ; dihydroay- 
phenyl-acetic acid (OH),—CH,.COOH (the homogentisic acid of 
Wolkow and Baumann);? and trihydroxyphenyl-propionie acid 
(OH),C,H,.C,H,.COOH (the uroleucie acid of Kirk). 

In the urine of herbivora other analogous compounds have been 


1 Cf. Halliburton, ‘‘ Chemical Physiology and Pathology,” 1891, p. 745. 
2 Loc. cit., 1891, Bd. xv. S. 241. This is that isomeric acid which is related to hydro- 
chinon. ~ 


CARBOHVDRATES AND RELATED SUBSTANCES. 607 


detected, and kynwrenie acid, a related substance, is an important consti- 
tuent of dog’s urine.? 


Pathologically, the substances just described may become of considerable 
importance. In carbolic acid poisoning many of them are excreted in greatly 
increased amount; pyrocatechin and hydrochinon may be present in large 
quantity, and then give rise, by their oxidation, to the peculiar coloration seen 
in carboluria. In certain diseases other members of the group are increased, 
and give rise to the phenomena of alcaptonuria. In this state the urine 
develops, on standing, a dark colour, like that seen in carboluria ; and 
Beedecker in 1861 isolated a substance which he termed alkapton, to the 
oxidation of which he held the colour due. Alkapton was shown by Marshall 
and Kirk to be impure uroleucic acid (vide supra). This latter substance, 
however, is not wholly responsible for the coloration phenomenon. Wolkow 
and Baumann? have recently shown that in a case investigated by them the 
“‘alkaptonuria” was almost wholly due to the presence of homogentisic acid 
(supra). Pyrocatechin is doubtless sometimes the cause.? Most hydroxy- 
derivatives of benzene in alkaline solution develop a dark coloration on 
exposure to the air? (cf. p. 630). 

The quantity of phenol and kresol in the urine is increased in extreme 
constipation, in obstruction of the lower bowel, in peritonitis, and in pyzemia 
(cf. indoxy]l, infra, and p. 631). 


Indoxyl and skatoxyl.—These, although nitrogenous compounds, 
are closely related to the substances just treated, and may fitly be 
considered here. 

Indoxyl (Cj,H,NH.CH.C.OH).—The so-called urinary indican is 
indoxylsulphuric acid. In normal urine on a mixed diet, the quantity 
present is only from 5 to 20 mgrms. In herbivora the quantity 
is much larger. It is absent from the urine of new-born children 
(Senator). Indoxyl is derived from oxidation in the body of the indol 
absorbed from the bowel, and its amount is increased, like that of the 
urinary phenols, by all causes which lead to increased bacterial decom- 
position of proteids, in the intestine or elsewhere ; and by circumstances 
which favour the absorption of the indol when formed (intestinal 
obstruction, etc.). Skatoxyl (CjH,NOH) is derived from skatol (methyl- 
indol), and accompanies indoxyl into the urine by parallel paths and 
from kindred causes. Like indoxyl, it is present as a conjugated 
sulphate. 

By oxidation indoxy] forms indigo-blue and indigo-red, while skatoxyl 
similarly yields red pigments. The consequent colour phenomena 
which arise in the urine are discussed under the head of the pigments. 


CARBOHYDRATES AND RELATED SUBSTANCES. 


Normal urine contains small quantities of ‘certain carbohydrates. 
Under ordinary circumstances the physiological limit extends only to 
a minute quantity of any one of these substances; but, in the urine of 
women during lactation, milk-sugar may oceur in very considerable 
amount, without departure from what must be considered physiological 
conditions. 


1 For phenaceturic acid, see under hippuric acid. ? Loc. cit. 

3 Cf. v. Jaksch, ‘‘ Klinische Diagnostik,” 4th edition, 1896, p. 415. 

4The behaviour of the alkaline solution of pyrogallic acid used in photography will 
be an example familiar to many. 


608 THE CHEMISTRY OF THE URINE. 


The general chemistry of the carbohydrates is elsewhere discussed. 
We shall deal only with their relation to the urme :— 

(a) Dextrose.—The question as to whether or not small amounts of 
grape-sugar are excreted in the urine during normal health has been 
much debated. It is needless to confuse the issue by an attempt to 
define what is meant by “normal” urine. We may ask rather, Does 
the urine of the average individual, living an ordinary life, upon ordi- 
nary diet, generally contain sugar? There can be little doubt, in the 
light of our present knowledge, that this question must be answered in 
the affirmative. 


Bricke ! was the first (in 1858) to state that sugar is normally present in 
human urine, and Bence Jones? was an early supporter of the view. For 
some years, however, the question was treated as an open one, and in 1871, 
Seegen, after careful study of the matter, decided that means were not then 
to hand by which its presence could be proved with certainty. Pavy,® in 
1878, affirmed that it was certainly a normal constituent, and has always 
maintained this position. Since then other observers (in England especially 
Sir G. Johnson and G. Stillingfleet Johnson *) have stoutly maintaimed the 
contrary. The chief criticism of the earlier methods of demonstration which 
gave positive results was that, while they depended upon reduction tests, they 
did not eliminate the influence of other reducing substances. The creatinin, 
uric acid, hippuric acid, and other aromatic constituents of the urime, all tend 
to reduce salts of the heavy metals in alkaline solution. It is admitted by all 
observers that normal urine exercises a reducing power on copper solutions, 
which, if due to glucose, would indicate the presence of about 0-1 to 0°3 per 
cent. of this substance. But it is equally admitted by all that a large part of 
this reduction is due to the other substances mentioned above. The question 
which has been at issue is as to whether any part of the reducing power is due 
to sugar. 

It is evident that we cannot rely alone upon reduction tests applied to 
the original urine. The more accurate knowledge that we now posesss with 
regard to the question has been obtained by three lines of investigation :— 
(1) By the application of direct tests which are unaffected by substances 
other than sugar; (2) by the use of methods which involve a preliminary 
removal of interfering substances; and (3) by the employment of means 
whereby the sugar itself is separated from the urine unmixed with the con- 
stituents which lead to error. 

1. The phenylhydrazine test of Fischer and v. Jaksch has given positive 
results in the hands of several observers when applied directly to normal urine.® 
The yellow crystals of phenylglucosazone may certainly be obtained from 
urine containing as little as 0-1 per cent. of sugar (v. Jaksch). In my own 
experience great care is generally necessary to secure unequivocal results in the 
case of normal urine. As a crucial test, it suffers the disadvantage of yielding 
crystals with the glycuronic acid compounds ; the amount of crystals obtain- 
able from normal urine direct being in general too small for discriminating 
tests to be applied to them. After the sugar has been previously isolated, the 
reaction with phenylhydrazine is, however, of the utmost value as a confirma- 
tory test (vide infra). 

A colour reaction may be observed in normal urine, which is held by some 
to be conclusive of the presence of sugar. This is the furfurol reaction. A 

1 Stitzungsb. d. k. Akad. d. Wissensch., Wien, 1858, Bd. xxix. S. 346. 

2 Journ. Chem. Soc., London, vol. xiv. p. 22. 

3 Guy’s Hosp. Rep., London, vol. xxi. p. 413. 

+ See articles and correspondence in the Lancet, London, during July and August 1894. 

® Cf. E. Roos, Zéschr. f. physiol. Chem., Strassburg, 1891, Bd. xv. 8. 523; A. H. Allen, 
‘*Chemistry of the Urine,” 1895, p. 89. 


DEXTROSE. 609 


small quantity of B-naphthol dissolved in chloroform is added, and then some 
strong sulphuric acid. The latter, by acting upon the traces of sugar present, 
produces furfurol, which, with the B-naphthol, gives a violet or carmine-red 
coloration.! This test is also affected by the presence of glycuronie acid. 

2. By treating the urine with mercuric acetate, creatinin and the various 
non-saccharine reducing substances are precipitated. G. 8S. Johnson has main- 
tained that in the filtrate obtained after treating a normal urine in this way, 
no sugar reaction can be observed. A. H. Allen has, however, obtained posi- 
tive results.” 


». By far the most satisfactory evidence is obtained by methods 
capable of isolating any sugar that may be present. Moritz, by treating 
5 to 6 litres of the urine of healthy men with lead salts and ammonia, 
and by decomposing the precipitate so obtained with sulphuretted 
hydrogen (Briicke’s method), was able to isolate a substance which gave 
all the reactions of grape-sugar. It was fermentable with yeast, yielded 
phenyleglucosazone crystals, was dextrorotatory, and reduced alkaline 
copper and bismuth solutions? Pavy, by a similar method, long ago 
obtained a fermentable reducing body from normal urine, and he has 
since extended his earlier results by showing that the substance yields 
phenylglucosazone.+* 

When solutions of carbohydrates are treated with benzoylchloride, 
they yield a precipitate of insoluble compounds (esters) with benzoic 
acid. Glycuronic acid gives no precipitate. Baumann has applied this 
fact to the separation of urinary carbohydrates; and, in the hands of 
Wedenski® and Baisch,® the method has yielded ver y convincing results. 
The last observer decomposed the benzoic esters he obtained from 
normal urine, with alcoholic soda, and isolated, inter alia, a sugar which 
gave, with phenylhy drazine, an osazone melting at the right temperature 
for that of glucose. The product g gave also all the other reactions of 
dextrose. The quantity found varied from 0:08 to 0-18 grms. in the 
twenty-four hours. 

The evidence we have detailed leaves little room for doubt that 
grape-sugar is a constituent of normal urine, and we may take the 
figures just quoted from Baisch as the most accurate estimate we possess 
of its amount. Pavy and y. Udransky found larger quantities, and 
Seegen considerably less, but their methods are perhaps more open to 
question from the quantitative point of view.” 


Alimentary glycosuria.—It is certain that many healthy individuals, after 
a meal rich in sugar, and especially after the consumption of an excessive 
amount of sugar in solution—as in sweet wines and the like—excrete tem- 
porarily quantities of sugar greatly in excess of the small normal constant we 
have just discussed. The explanation of this is probably to be found in the 
observation of Ginsberg,’ that when large quantities of sugar are present 


1 Molisch, Centralbi. f. d. med. Wissensch., Berlin, 1888, Nos. 34 and 49. Also Luther, 
Chem. Centr.-Bl., Leipzig, 1891, Bd. ii. S. 90 ; v. Udransky, ‘Ztschr. Ff. physiol. Chem., Strass- 
burg, 1888, Bd. xii. S. 380. 

? Loe. cit., p- 19. 

3 Deutsches Arch. f. klin. Med., Leipzig, 1890, Bd. xlvi. S. 252. A complete review of 
the earlier literature will be found in this paper. 

4 << Physiology of the Carbohydrates,” 1894, p. 180 e¢ seq. 

5 Ztschr. f. physiol. Chem., Strassburg, 1889, Bd. xiii. S. 122. 

6 Tbid., 1894, Bd. xviii. Ss. 193; 1895, xix. §) 348 ; xx. S. 249. 

7 For a criticism of Briicke’s lead- -precipitation method, see Colls, Journ. Physiol., Cam- 
bridge and London, 1896, vol. xx. p. 109. 

8 Arch. f. d. ges. Physiol, Bonn, 1889, Bd. xliv. S. 306. 


VOL. IL.—39 


610 THE CHEMISTRY OF THE ORINE. 


in the bowel, some may be absorbed, not by the ordinary path of the capil- 
laries and portal vessels, but by way of the lacteals and thoracic duct, thus 
escaping the influence of the liver. The percentage of sugar in the blood i is 
thereby increased, and the excess is excreted by the kidneys. A distinction 
between such cases and those in which diabetes exists, is seen in the fact that 
the “alimentary glycosuria” is not produced by starchy foods, however large 
the quantity taken, but only by excess of ready-formed sugar in the diet.! 
According to Moritz, dextrose, levulose, cane-sugar, and probably milk-sugar, 
may all appear unaltered in the urine when severally taken by the mouth in 
considerable quantity (e.g. 200 grms.). Such alimentary effects last from 
three to six hours.? 

Pathological glycosuria.—The great increase of dextrose in the urine 
of diabetes is a familiar phenomenon. Its excretion may range in this disease 
from quite small quantities up to 500 or 600 grms. per diem. The morning 
urine is apt to contain least sugar; that passed three or four hours after a 
meal generally contains most. 

In other diseased conditions, quite apart from diabetes, a special tendency 
has been observed to the occurrence of an alimentary glycosuria; gout, 
exophthalmie goitre, and certain nervous diseases may be instanced. An 
increase of reducing substances, almost certainly consisting at least in part of 
dextrose, is said to be found in the urine of some pyemic ‘conditions, As the 
effect bE certain drugs and toxic substances, such as chloral, chloral amide, 
morphine, hydrocyanic acid, turpentine, and carbon monoxide, the urine 
commonly reduces copper solutions ; but in most of these cases the reduction 
is due to conjugated compounds of glycuronic acid, and not to dextrose 
(vide p. 613). 

The detection and estimation of dextrose, which, as we have seen, have 
proved difficult problems in the case of the minute amount normally present 
in urine, become easy when the increased amount excreted in disease is to be 
dealt with. The methods used depend upon the reducing power which the 
sugar exerts upon metallic salts, or upon certain coloured organic substances, 
and these may be checked by the fermentation of the suspected urine by 
means of yeast, by the indications of the phenylhydrazine test, and again by 
the use of the polariscope. Of reduction tests a great number have been 
proposed; we shall here refer to two only. The well-known Fehling’s test 
consists of a solution of copper sulphate of definite strength, mixed with caustic 
alkali and alkaline tartrates (Rochelle salt). The presence of the last pre- 
vents the precipitation of cupric oxide when the solution is boiled by itself, 
but allows the precipitation of yellow or cuprous oxide when reduction has 
occurred from the action of the sugar. The reduction may be observed, 
after boiling the liquid, if the urine contain not less than 0-2 per cent. of 
dextrose. If less than about 0°5 per cent. be present, no precipitation occurs 
until after cooling, when the liquid becomes opaque, and of a greenish colour. 
With larger amounts a definite precipitate of a yellow or red colour is seen, 
immediately after heating the test with a small proportion of the urine. 
Nylander’s solution has some advantages over Fehling’s, in that it is much less 
affected by creatinin, urates, and reducing bodies other than sugar (vide supra). 
It is a modification of the bismuth test, originally suggested by Bittcher, and 
is prepared with the same reagents as Fehling’s solution, but with the sub- 
stitution of basic nitrate of bismuth for the copper sulphate. On boiling this 
solution with urine containing sugar, the liquid turns black. The reaction is 
easily seen if 0°l per cent. or upwards of dextrose is present. 

Both solutions are reduced by lactose and by glycuronie acid; but the 
former of these substances can only be present under special circumstances 


1 Of. Neumeister, ‘‘ Lehrbuch der physiol. Chem.,” Th. 2, S. 306. 
2 Moritz, Centralbl. f. klin, Med., Bonn, Bd. xii, No. 28. 


LA VOLOSE—LACTOSE. ; 611 


(infra), while the latter is never present in the urine in amounts large 
enough to lead to confusion with , glycosuria in the pathological sense ; 
except when quite special substances have been taken by the mouth. But 
in order to make the identification of glucose more certain, we may confirm 
the results of a reduction test by means of yeast fermentation. Lactose and 
glycuronic acid do not ferment. The urine should be placed in a test-tube 
. so as completely to fill it, and the tube inverted over a basin containing a 
further quantity of the urine. After ascertaining that no air is present, a 
small piece of pressed yeast is passed under the inverted tube, and the latter 
secured in position with a clamp. The tube is then allowed to stand at a 
temperature of 25° to 30° C. In twelve hours, if dextrose be present in 
quantity, a notable amount of carbon dioxide will have collected in the upper 
part of the tube. The fermentation test is very conclusive, but it is not easily 
obtained when less than 0°5 per cent. dextrose is present. With phenyl- 
hydrazine, however, as already stated, urines containing as little as 0:1 per 
cent. will yield easily recognisable crystals of phenylglucosazone. The fact 
that levulose also ferments with yeast, and yields an identical glucosazone, is 
of little importance in practice ; this sugar is rarely present (imjra), and except 
under special circumstances it is unnecessary to distinguish it from dextrose. 

For the estimation of dextrose, modifications of the various tests just 
described are employed. We may ascertain, for instance, how much of a 
given specimen of urine is required to precipitate all the copper from a 
measured quantity of standardised Fehling solution. Or, with greater con- 
venience, we may employ the modified copper test known as Pavy’s solution. 
This contains a large excess of ammonia, in addition to the ordinary constitu- 
ents of Fehling’s' test. In ammoniacal solution cupric salts are blue, but 
cuprous salts are colourless. By noting, therefore, the amount of the urine 
(diluted, if necessary, to a known bulk) which is necessary to decolorise a 
given quantity of the standard Pavy’s test, we obtain a measure of its reducing 
power, and so of the dextrose present. Again, we can adapt the fermentation 
test to quantitative purposes, by measuring the CO, produced from a definite 
quantity of the urine, or by ascertaining the diminution in the specific gravity 
of the fluid which follows the destruction of the sugar by the yeast. Lastly, 
we may employ the polarimeter, which indicates the percentage of dextrose by 
the number of degrees through which a polarised ray is turned to the right 
on passing through a layer of urine of determinate depth. A drawback to 
the use of this instrument, when applied to the urine, arises from the fact 
that other substances may be present which are optically active.! 


(b) Leevulose.—The occurrence of levulose in normal urine has not 
been observed; but in certain cases of glycosuria it is said to be present. 
Kulz? separated from the urine of a diabetic a levorotatory sugar, 
which possessed all the properties of ordinary levulose, except that, 
unlike the latter, it was precipitated by basic acetate of lead. When 
levulose is given by the mouth in diabetes, it can be utilised in 
metabolism more readily than dextrose, and within certain limits of 
administration it is not excreted in the urine. Beyond these limits, 
however, it is eliminated partly unaltered and partly as dextrose.’ 

(c) Lactose.—That a reducing substance is apt to appear in the urine 
of women during the period of lactation, was first observed by Heller as 
far back as 1849; and F. Hofmeister, in 1877, showed definitely that 


1 Details of all these processes will be found in practical handbooks. 

2 Ztschr. f. Biol., Miinchen, 1890, Bd. ix. S. 228. References to the earlier literature 
will be found in this paper. 

3 Cf. Haycraft, Zischr. f. physiol. Chem., Strassburg, Bd. xix. S. 137; Hale White, 
Guy's Hosp. Rep., London, 1893, p. 133. : 

4 Ztschr. f. physiol. Chem., Strassburg, 1877, Bd. i. S. 104. 


612 THE CHEMISTRY OF THE URINE. 


this was milk-sugar. Only lately, however, has it been recognised that 
lactosuria is an almost constant phenomenon during lactation. Even 
when the conditions are altogether favourable and normal, it is seldom 
that the sugar is not present in the urine at some portion of the period. 
When any interruption to the natural removal of the milk occurs, the 
amount may be very considerable. 

The phenomenon is easily understood when it is remembered that 
the lactose excreted into the blood from the mammary gland does not 
come under the normal influence of the liver. Recent researches, 
indeed, indicate that milk-sugar cannot in any case act as a precursor 
of glycogen, until it has been inverted. When lactose is taken by the 
mouth, this inversion occurs before or during absorption from the bowel. 


The complete identification of lactose in the urine is difficult, unless it be 
first isolated by processes too lengthy to be described here. But if the urine 
exhibit the following characters, the presence of lactose is established almost 
without the possibility of doubt. It should reduce copper and bismuth solu- 
tion ; but, with the fermentation test, it should give negative results for the 
first twenty-four hours of the experiment, and it should give no definite erystal- 
line precipitate with the phenylhydrazine test when this is directly applied.1 
On the other hand, after boiling with 5 per cent. sulphuric acid for a short time, ° 
the urine should, if first neutralised with ammonia, give the phenylhydrazine 
test readily; crystals of dextrosazone should be thus obtained, and, with 
proper precautions, galactosazone crystals may be also distinguished. Although 
the lactose is converted by the mineral acid into dextrose and galactose, a 
fermentation is not always to be obtained after treatment, as the large amount 
of sulphate, which is present after neutralising the acid, interferes with the 
growth of the yeast. If the reducing power of the urine be estimated, this 
should be found increased after boiling with mineral acid, but unaffected by 
boiling with citric acid. 


(d) Pentoses— A ylose, arabinose (C;H,,0;)—Ebstein,? Salkowski,? and 
others have observed the presence of 5-carbon sugars in the urine. 
They are generally, when present, derived from the food, and then pro- 
bably arise from certain fruits, especially cherries and plums, which 
contain either pentoses or a precursor of these sugars, the so-called 
“fruit gum.” The pentoses are apparently assimilable with difficulty. 
Under exceptional circumstances, it seems possible that they may 
arise in the organism, as the result of disordered metabolism. It has 
been found that a certain proteid, derived from the pancreas, yields 
pentoses when boiled with acids, and some such substance may be the 
source of pentosuria. 


The pentoses give a red coloration when treated with strong hydrochloric 
acid in the presence of phloroglucin (Tollens’ reaction). Glycuronie acid, 
however, behaves similarly. They reduce copper solutions, and yield an 
osazone after somewhat prolonged warming with phenylhydrazine, but they 
do not ferment. 


(e) Isomaltose.—When the mixture of carbohydrates obtained from 
normal urine by precipitation with benzoylchloride is fermented with 
yeast, so that all the dextrose present is destroyed, there remain small 


* Lactosazone does not crystallise readily, except from pure solutions of the sugar. 

2 Virchow’s Archiv, 1892, Bd. cxxix. S. 401; exxxii. S. 368. 

3 Centralbl. f. d. med, Wissensch., Berlin, 1893, 8. 193; Berl. klin. Wehnschr., 
1895, No. 17. 


ANIMAL GUM—GLYCURONIC ACID. 613 


quantities of a sugar, which, though not fermentable, gives a well- 
crystallised osazone, and reduces Fehline’s solution. According to the 
researches of Baisch} the properties of this substance agree with those 
of “ isomaltose.” 

(f) Animal gum.—The third and remaining carbohydrate which 
separates from normal urine when this is tr eated with benzoylchloride, 
is a dextrin-like substance, in all probability identical with “animal 
gum.” This was first isolated from urine by Landwehr,? who took 
advantage for this purpose of the insolubility of its copper compound. 
Its presence has been confirmed both by Wedenski and Baisch, who 
employed the benzoylehloride method. 

The substance does not reduce metallic salts, but, on the other hand, 
on boiling with mineral acids, it yields a derivative which will reduce 
Fehling’s and Nylander’s reagents freely. Simultaneously it yields 
(like many other carbohydrates and certain of the aromatic constituents 
of the urine) with acids a brown flocculent precipitate of the “iwmous 
substances” of v. Udransky.? It is due to the presence of this substance 
that the reducing power of most uries is increased after boiling with 
mineral acids. 

(g) Glycuronic acid.—The chemical relationship of this acid to the 
glucoses is seen by a comparison of their respective formule :— 


CH,HO(CH.OH),CHO COOH.(CH.OH),CHO 
(glucose) (glycuronic acid) 


It is derived from these sugars by oxidation of the primary alcohol 
group, CH,.OH, to the carboxyl group, COOH. It is at once, therefore, 
an aldehyde and an acid. As an aldehyde, it reduces copper solutions. 

It should be understood that glycuronic acid is never a constituent 
of normal urine in appreciable amount, nor does it appear as the result 
of pathological processes in the ordinary sense. Its presence almost 
always depends upon the ingestion of special substances, which are for 
the most part foreign to ordinary foodstuffs ; and, when excreted, it is 
“conjugated” with these, or with derivatives of these. 

It is apparently an intermediate product in the metabolism of 
carbohydrates, which, normally, becomes fully oxidised in the body ; 
but which, when conjugated with the exceptional substances referred to, 
escapes oxidation, and appears in the urine, just as the easily oxidisable 
glycin is protected by conjugation with benzoic acid and appears as 
hippuric acid. 

Some of the substances which form these conjugated compounds 
with glycuronic acid, are those which ordinarily form conjugated or 
ethereal sulphates (cf. pp. 606 and 631), especially the aromatic hydroxy- 
compounds. Phenol- indoxyl- and skatoxyl-glycuronic acids and many 
analogues have been described in the urine. But apparently the sulphate 
conjugation is the more constant process, and it is only when the above 
substances are present in very large amount that their glycuronic con- 
jugates appear in addition to their sulphuric acid compounds,—in 
general, only when they, or their precursors, are given abundantly by 
the mouth for the purposes of experiment. 

Of more practical importance are thos- Spihirited compounds of 


' Baisch, Ztschr. f. physiol. Chem., Strassburg, Bd. xx. S. 249. 
2 Centralbl. F. d. med. Wissensch., "Berlin, 1885, S. 369. 
° Zischr. f. physiol. Chem. , Strassburg, 1888 , Bd. xii. 8. 33. 


614 THE CHEMISTRY OF THE URINE. 


glycuronic acid with members of the fatty group of alcohols, which are 
excreted after the use of certain common drugs. Thus, when chloral 
hydrate is being taken, trichlorethylglycuronie acid (urochloralic acid)? 
is often found in the urine, and analogous compounds arise after the 
administration of butylchloral hydrate and chloroform. 

All these compounds are levorotatory, though glycuronic acid itself 
is dextrorotatory ; many of them, urochloralic acid for instance, reduce 
bismuth and copper solutions freely, and their presence may therefore 
lead to error in testing for sugar; but they are not fermentable. They 
split up with varying degrees of ease into glycuronic acid and the 
conjugated substance, either by boiling with mineral acids, or when 
heated with water in sealed tubes ; some (eg. phenolglycuronic acid) 
decompose when boiled with water alone. 

Glyecuronie acid itself is a syrupy substance, soluble in water and 
alcohol; but when its aqueous solutions are boiled or evaporated, it 
loses water, and forms a crystalline anhydride which is insoluble in 
alcohol. 


To separate the urinary glycuronic compounds, a large quantity of urine is 
precipitated with acetate of lead, and the precipitate decomposed with 
sulphuretted hydrogen. After filtering, barium hydrate is added to the 
solution. The sulphates and phosphates thus precipitated are filtered off, and 
alcohol added to the filtrate, whereupon the barium salts of the conjugated 
glycuronic acids crystallise out.” 


OTHER ORGANIC COMPOUNDS. 


Oxalic acid.—Small quantities of oxalic acid (COOH), are present 
in all specimens of urine, about 50 mgrms. being the average for the 
day’s excretion. Much of this may arise directly from preformed 
oxalates ingested with the food, as all vegetable food contains traces of 
these salts, and direct experiment has shown that they are susceptible 
of but very incomplete oxidation in the body.’ But oxalic acid does 
not disappear from the urie when pure flesh-food is taken, nor even 
during starvation;* it would thus seem certain that it can arise 
from proteid metabolism. It is, in certain cases, very largely increased 
in amount, from causes which are not clearly understood. Some 
authorities hold that these cases of “oxaluria” depend always upon 
excess of preformed oxalates in the diet; but no one who has observed 
the marked tendency to increased oxalate excretion in diabetes, or the 
way in which, in some cases of glycosuria, a temporary decrease in the 
sugar may be associated with an increase of oxalates, can doubt that it 
may arise also from incomplete oxidation of carbohydrates. 

Oxalate of calcium frequently separates from the urine to form a 
crystalline deposit. It mostly takes the form of the so-called 
“envelope crystals,” but may appear as dumb-bells, and is often seen as 
clear ovoids (Fig. 56). Itis responsible for the formation of a variety of 
urinary calculus. 


1This was the first of these substances to be described, vide Musculus and vy. Mering, 
Ber. d. deutsch. chem. Geselisch., Berlin, 1875, Bd. viii. S. 662. 

2 Cf. Ashdown, Brit. Med. Journ., London, 1890, vol. i. p. 169. 

3 Gaglio, Arch. f. exper. Path. u. Pharmakol., Leipzig, 1887, Bd. xxii. S. 246. 

*Marfori, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1892, 8. 72. 


ACIDS AND HYDROXVACIDS. 615 


To demonstrate the presence of oxalic acid, and to estiémate its amount, a 
litre of urine should be treated with calcium chloride and ammonia, and 
afterwards made acid with acetic acid. After twenty-four hours’ standing, 
the crystalline precipitate, which contains uric acid crystals mixed with 
calcium oxalate, is filtered off and treated with dilute hydrochloric acid. The 
oxalate dissolves, and is reprecipitated, after filtering off the uric acid, by the 
addition of ammonia. At a dull red heat it is converted into caleium 
carbonate, and may be weighed as such. 


Fic. 56.—Calcium oxalate. 


Acids and hydroxyacids of the fatty series, with derived 
substances.—Normal urine contains minute quantities of the volatile 
fatty acids, especially acetic, but also formic, propionic, and butyric 
acids.t They do not, as a rule, amount collectively to more than some 
50 mgrms. in the day’s excretion, and they arise doubtless from the 
bacterial decomposition of carbohydrates and proteids in the lower 
bowel. Fatty acids of low atomic weight, such as the above, are less 
easily oxidised in the organism than are those of greater complexity.” 


The amount is considerable in the urine of herbivora, and in man it is 
increased by many diseases, especially by such as lead to increased decomposi- 
tion in the bowel, or to prolonged constipation. 

When a specimen of urine undergoes ammoniacal fermentation, the 
volatile acids are increased at the expense of the carbohydrates it contains.® 

These acids are obtained from the urine by distillation with phosphoric 


'Cf. v. Jaksch, Ztschr. f. physiol. Chem., Strassburg, 1886, Bd. x. S. 536. The 
earlier literature is here summarised. 

2C. Schotten, ibid., 1883, Bd. vii. S. 375. 

3 Salkowski, ibid., 1889, Bd. xiii. S. 264. 


616 THE CHEMISTRY OF THE URINE. 


acid. They are found in the distillate so obtained, together with traces of 
hydrochloric and benzoic acids, phenol, and acetone. 

Sarcolactic acid is not a normal component of human urine, but it appears 
in many diseased or abnormal conditions of the body, of which it may be said 
generally that they involve either a suspension of normal hepatic functions or 
interference with the proper oxidative processes of the body.’ It was first 
observed in the urine of phosphorus poisoning, and of acute yellow hepatic 
atrophy,” and may be always demonstrated in these conditions. It is found 
also after slow asphyxia; in poisoning by carbon monoxide, in prolonged 
anemia, and shortly before death in very many diseases. That it may appear 
after prolonged and severe exercise, is doubtless explained by the fact that 
oxidation in the body has not kept pace with the increased production of 
lactates in the muscles.* 

The three closely related substances, B-hydroz, ybutyric acid, acetacetic 
acid (diacetic), and acetone rise to importance only in diabetes, but small 
quantities of the last may be found in normal urine, and all may be increased 
in disease apart from glycosuria, The following equations show the relation 
which obtains between them : 


CH,CH(OH).CH,.COOH + O = CH,.CO—CH,.COOH + H,O 


(8-hydroxybutyrie acid) (diacetic acid) 
CH,.CO—CH,.COOH = CH,.CO.CH, + CO, 
(diacetic acid) G@eeione) 


The first only appears in the urine in conjunction with the others, but 
either of the two latter may be found alone. Large amounts of all three may 
be found in diabetes; of the hydroxy-acid many grammes may be passed in 
the day. 

The presence of diacetic acid may be demonstrated by making the urine 
acid with sulphuric acid, and shaking with ether; the latter, which extracts 
the substance, is then transferred to another vessel, and is shaken with a weak 
aqueous solution of ferric chloride, which, if acetacetie acid was present in the 
urine, becomes of deep burgundy wine colour. 

In testing for the hydroxybutyrice acid, advantage is taken of the fact that 
it yields a volatile derivative, a crotonic acid, on distilling with sulphuric acid. 
This substance crystallises out from the distillate of the urine, and may be 
identified by its melting point (72° C.). The urinary hydroxybutyric acid is 
levorotatory. 

Acetone is identified in a urinary distillate by first adding a few drops of a 
solution of sodium nitroprusside, and then caustic alkali, whereupon, in the 
presence of acetone, a fine cherry-red colour is produced. Acetic acid subse- 
quently added in excess changes the colour to purple (Legal’s test). 


THE COLOUR OF URINE AND THE CHEMISTRY OF THE PIGMENTS. 


It is a familiar fact that, under physiological conditions, the urine 
may be almost colourless, or may exhibit tints varying from a pale 
straw yellow, through deep orange, to reddish brown. In its commonest 
condition it is yellow. Pathologically, the colour may undergo variations 
wider than those seen in health. 

1 Cf. Araki, Ztschr. f. physiol. Chem., Strassburg, 1895, Bd. xix. S. 422, with reference 
to previous papers by this author. 

* Schultzen u. Riess, Chem. Centr.-Bl., Leipzig, 1869, S. 681. 

8 Colasanti and Moscatelli, Arch. f. exper. Path. u. Pharmakol., Leipzig, 1890, Bd. 


xxvii. S. 158. 
4 Cf. Minkowski, zbid., 1893, Bd. xxxi. S. 183. 


THE COLOUR OF URINE. 617 


An effort has been made to refer the varying degree of pigmentation 
to a standard colour scale, so that the condition of a given specimen, as 
regards colour, might be quantitatively expressed. But much difficulty 
intervenes, in that variations may be due, not alone to differmg amounts 
of a single colouring matter, but to independent and quite irregular 
variations in at least three or four. The endeavour to attain to quanti- 
tative precision has on this account proved unsuccessful in practice.! 
We may content ourselves with speaking of physiological urine as pale, 
normal, or high-coloured respectively, and assist the description by 
comparison with other substances of familiar appearance (“ straw- 
coloured,” “sherry-coloured,” etc.). 

Pale urine is usually of low density, and contains a small proportion 
of solid matter. It results from all causes which promote a copious 
flow of fluid from the kidneys, such as free ingestion of liquids, a check 
to the cutaneous transpiration (as from the effect of cold), and emotional 
excitement. 

High-coloured urine is generally of high density, and is excreted 
when the transpiration from the skin is more than usually free, or 
under conditions of high metabolic activity. After a full meal the 
urine is often at once copious and of full colour. 

In general the amount of pigment rises with an increase in the con- 
stituents excreted by the renal epithelium, and not with the glomerular 
excretives. The depth of colour may be affected by the reaction of the 
urine; other things being equal, an acid urine will show a darker tint 
than one that is alkaline. 

Examined directly by means of the spectroscope, fresh normal urine 
is found nearly always to show no definite absorption-band ; a diffuse 
absorption of the more refrangible rays being alone evident. 


But by the aid of the spectrophotometer? we may measure the amount of 
light absorption in any region of the spectrum apart from the presence of 
actual bands. When light passes through urine, the amount of absorption 
increases progressively from the mid-red to the violet. 

Suppose the absolute absorption at any two points in this region of 
spectrum be measured ; say in the neighbourhood of the Fraunhofer lines, E 
and F respectively. If in any one specimen of normal urine the absorption 
near F is found to be twice as great as that near EK, then if the urine contained 
but one pigment, this same ratio would be found in any other specimen. The 
absorption at F would in all cases be double that at E. For, clearly, the 
dilution of an individual pigment would decrease the absolute absorption 
throughout the spectrum, but would leave the relative absorption at any two 
points unaffected ; similarly, concentration would increase the absolute, but 
would nowhere affect the relative, absorption. But different specimens of 
normal urine do not agree in this way. One urine may show more relative 
absorption (say) in the mid-green, another more in the blue. ‘This can only be 
due to the fact that more than one pigment is concerned.? Although it yields 
no definite bands, the spectroscopic properties of fresh normal yellow urine 
thus indicate some complexity in its pigmentation ; but the same experimental 
evidence indicates nevertheless that no more than one pigment is usually 
present in a relatively large amount. 


1 By the use, however, of Lovibond’s tintometer, the colour of urine under varying 
circumstances may be very exactly imitated, and expressed i in terms of a scale. 

* See this textbook, article “Hemoglobin,” p. 213. 

° This argument only holds for colouri ing matters which do not under go dissociation in 
solution. 


618 THE CHEMISTRY OF THE URINE. 


The pigments of the urime have long received attention and have 
been the subject of many laborious researches ; but, owing to the great 
difficulties they present to the investigator, our knowledge of the 
chemistry of most of them has remained indefinite. These difficulties 
arise from various causes. Pigment metabolism appears to be always 
of a highly conservative nature. The colourig matters found in the 
epidermal structures of animals, serving for ornament, protection, or 
other purposes, are almost always present in strikingly small quantity ; 
and those which are purely excretory leave the body in equally small 
proportionate amount. 

The highly developed optical activity of these substances, which has 
led us to group them together in a special class as “ pigments,’ at the 
same time gives to them a prominence in various phenomena, dispro- 
portionate to the actual quantity in which they are present. The 
urinary pigments are (at least, under normal conditions) quite minute 
in amount, and this fact is the primary difficulty in the path of chemical 
investigation. As Bunge has written, many endeavours have resulted 
merely in applying Greek and Latin names to substances which have 
been obtained in quantity too small for proper investigation. 

The extremely delicate indications of the spectroscope have been of 
the greatest assistance in overcoming this fundamental difficulty, and 
our knowledge of pigments has been much extended by its use. But 
evidence so gained has to be checked and assisted by other methods. A 
complex spectrum may indicate a mixture of substances; but it may, 
with equal probability, be due to one alone. A mixture, on the con- 
trary, may show but a single absorption-band, for the reason that of the 
pigments present one alone extinguishes light in a specific region. 

It is therefore easy, by a mere qualitative use of the spectroscope, 
to mistake a mixture for a chemical individual. On the other hand, 
very slight variations in the physical condition of a pigment, or a 
minute change in its molecular constitution, may produce a_ great 
effect upon its spectrum, and, unless we are aware of these conditions, 
we may be led to see wide differences where chemically there is little or 
none. 

When, again, endeavours are made to isolate pigments by chemical 
means, the great instability which they exhibit as a class is apt to lead 
to error. So often has. this danger been overlooked, that we are 
compelled to attach no importance, “bey ond what accrues from historic 
interest, to much of the work which has been done on this problem. 

It is of prime importance, when we endeavour to obtain these 
unstable substances in their integrity, that the use of highly active 
reagents should be avoided. 

“We shall deal only with the pigments of which we have comparat- 
ively accurate knowledge; but it may be safely asserted that the four 
substances now to be described form the basis of urinary chromatology. 
These are wrochrome, urobilin, uroerythrin, and heematopor “phyrin. Other 
pigments exist, and some have doubtless yet to be recognised, but they 
are exceptional, or take but very small share in the coloration of the 
urine. 

Preformed pigments of normal urine—(a) The essential yellow 
pigment, urochrome.—In 1864,Thudichum gave the name of urochrome 
to preparations obtained from normal urine by complicated processes of 
extraction. Thudichum’s products undoubtedly contained a large pro- 


PREFORMED PIGMENTS OF NORMAL URINE. 619 


portion of the substance we are now to describe, but they were mixed 
with urobilin and with decomposition products. 

To A. E. Garrod! we owe a process for the extraction of the essential 
yellow colouring matter, which is beyond reproach in its avoidance of 
destructive reagents. It yields a product entitled to be considered, with 
a large degree of probability, as a chemical individual. 

Following Garrod, we shall describe this pigment under the name of 
urochrome—a name eminently fitted for a substance which is the prime 
cause of the familiar colour of urine, but in the use of which we must 
avoid historical confusion. 

Between the urochrome of Garrod and that described thirty years 
earlier there is the difference between presumptive chemical individual- 
ity and almost certain admixture. It should be stated, however, that 
Thudichum still holds the pigment described by him to be a definite 
substance, and has recently investigated certain of its reactions, which he 
believes indicate for it the combined characters of an alcohol and a base. 


Separation of wrochrome (Garrod).—The urine is saturated with crystals 
of ammonium sulphate, and, after standing, is filtered (vide infra, “ Separation of 
Urobilin”). The filtrate, which is still almost as highly coloured as the original 
urine, is shaken with alcohol. The latter solvent separates rapidly from the 
saline mixture, and is seen to withdraw a large proportion of the colouring 
matter. Repeated extraction removes practically all. The alcoholic solution 
is diluted with a large bulk of water, and the mixture again saturated with 
ammonium sulphate ; by this procedure the alcohol is again made to separate 
from the water, carrying the pigment with it, and a satisfactory washing of 
the original extract is secured. This second alcoholic solution is now made 
just alkaline with ammonia, and evaporated to dryness ; the residue is 
extracted once or twice with acetic ether, which removes certain impurities, 
and is again dissolved in strong alcohol. Somewhat prolonged digestion is 
necessary at this stage, as the solubility in alcohol is decreased when the 
pigment has once been taken to dryness. Finally, the alcohol is concentrated 
till it has a deep orange colour, and is poured into at least an equal volume of 
ether, when an amorphous brown precipitate falls, consisting of the greater 
portion of the pigment present, in almost pure condition. The precipitate 
may be filtered off, dried on the paper, and washed with a little chloroform 
and absolute alcohol.” 


Properties.—The substance so prepared is a hygroscopic, brown, 
amorphous substance, easily soluble in water, much less soluble in 
alcohol; only slightly soluble in acetic ether, amyl alcohol, or acetone ; 
and insoluble in chloroform, ether, and benzene. Its solutions show no 
definite spectroscopic absorption-bands, even after the addition of acids. 
Zine chloride and ammonia produce no fluorescence. Alkalies give the 
solution a brownish tint, acids a reddish brown. The pigment forms 
insoluble compounds with the heavy metals, and is precipitated by 
phosphotungstic and phosphomolybdic acids. With strong nitric acid 
it undergoes a colour change resembling the xantho-proteic reaction. 

Urochrome we have seen to be a pigment which can be removed 
from the urine without the use of strong reagents, and in the removal 
of which the fluid loses nearly all its colour. At the same time, its aqueous 


1 Proc. Roy. Soc. London, 1894, vol. lv. p. 394. 

2 See also Kramm, Deutsche med. Wehnschr., Leipzig, 1896, Bd. xxii. S. 25 and 42. This 
author separates the pigment by an entirely different method. He confirms Garrod’s 
original account of its properties. 


620 THE CHEMISTRY OFTHE URINE: 


solutions have a tint like that of urine itself, and, like normal urine, 
show no absorption-bands. There can be no doubt, therefore, that it is 
the essential cause of normal urinary coloration. 

Physiological relations.—Until quite recently, we had no knowledge 
of the chemical relationship, or of the metabolic precursors of this im- 
portant physiological pigment. But Riva! and Chiodera* have obtained, 
by the action of potassium permanganate upon solutions of urobilin, 
a substance which they believe to be identical with urochrome. A. E. 
Garrod® has added still more conclusive evidence for the existence 
of a simple relation between this pigment and urobilin, by observing 
that alcoholic solutions of pure urochrome, when treated with aldehyde 
(which we may believe acts as a mild reducing agent), yields a pigment 
showing the spectrum and all the more characteristic properties of 
urobilin. The establishment of this relation is most important in 
bringing our knowledge of physiological pigments into line, since, as 
will be shown immediately, the derivation of urobilin from blood and 
bile pigments is clearly established. We can now ascribe a similar 
origin to the fundamental colouring matter of urine. 

“(b) Urobilin.—In 1868, Jatt as an outcome of a spectroscopic 
study of the urine, discov ered a pigment with well-characterised pro- 
perties, to which he gave the name of urobilin. 

This pigment is perhaps scarcely entitled to be classified among 
the preformed pigments of normal urine, for it is present as a rule in 
minimal amount and almost always in the form of a chromogen. But on 
rare oceasions the free pigment is found in the fresh urine of normal 
individuals, and, moreover, the importance of urobilin m other respects 
makes it necessary to give it a prominent place in this section. It was 
the first physiological urinary pigment of which we had accurate know- 
ledge from the point of view of genesis and metabolic history. Its 
increase in disease is a familiar phenomenon. These facts and its well- 
marked spectroscopic characters have made it predominant in the 
literature of urinary pigments. Even at the present time it is some- 
times described as the essential colouring matter of urine, an error 
which is at once demonstrated if the spectroscopic indications of normal 
urine and of weak solutions of pure urobilin are compared. 


Separation.—When zine chloride and ammonia are added to urine in due 
proportion, a precipitate is obtained (cf. “ Separation of Creatinin,” p. 599), which 
contains much of the urobilin present. This method of precipitation was used 
by Jaffé, and from the zine precipitate he succeeded in extracting the pigment 
in a remarkably pure condition, but in small quantity, and by a somewhat 
complicated procedure. 

Méhu ® later showed that saturation of the urine with ammonium sulphate, 
after acidification with weak sulphuric acid, produced a complete precipitation 
of this pigment. The precipitate thus produced, which mainly consists of 
pigmented urates, will yield to acid alcohol a solution, in which the character- 
istic absorption-band of acid urobilin, to be later described, is easily seen. 
Even when normal urine has been employed, the spectrum may be observed 
after this procedure, for the bandless chromogen is decomposed by the acid 

1 Gazz. med. di Torino, 1896, vol. xlvii. No. 12. 

2 Arch. ttal. di clin. rie: ; Milan, 1896, aa SRV Ps 00. 

3 Journ. Physiol., Cambridge and London, 1897, vol. xxi. p. 190. 

1 Centralbl. f. d. med. Wissensch., Berlin, 1868, Bd. vi. 8. 243 ; Virchow’s Archiv, 1869, 
Bd. xlvii. S. 405. 

> Bull, Acad. de méd., Paris, 1878, tome vii. p. 671. 


UROBILIN. 621 


employed. When a urine rich in urobilin is saturated with ammonium 
sulphate (best after previous removal of the urates by preliminary saturation 
with chloride of ammonium), and acidified with sulphuric acid, it will yield 
the pigment w hen shaken with a mixture of ether and chloroform. From this 
organic solvent distilled water will again remove all the urobilin, and from 
the water it may be precipitated by the further use of ammonium sulphate. 
A method of separation may be based upon these facts which will yield a 
very pure product in comparatively large amount.! 


Properties—Urobilin is an extremely soluble substance, dissolving 
freely in all ordinary solvents. It is, however, proportionately less 
soluble in water than is urochrome, though much more readily soluble 
than the latter in alcohol and other organic liquids. Its solutions, when 
concentrated, have a brown colour; when more dilute they are yellow; 
on great dilution they exhibit a highly characteristic change to a dull 
pink colour. 

An alcoholic solution of the pure pigment free from extraneous acid 
or alkali exhibits a green fluorescence quite apart from the addition of 
reagents. When, however, zinc chloride and ammonia are added, a 
greatly increased fluorescence is produced. This striking reaction is of 
much value in the identification of urobilin; it may be obtained after 
great dilution. 

Solutions of urobilin exhibit very definite spectroscopic phenomena. 
In clear acid solutions of moderate strength, a single absorption-band is 
seen between the Fraunhofer lines 6 and F, slightly overlapping the 
latter ; situate, therefore, at the junction of the green and blue of the 
spectrum (Fig. 57, Spectrum 4). In highly concentrated solution this band 
is lost in a general absorption of the more refrangible rays. On diluting 
such a concentrated solution a broad band first appears with a region of 
complete blackness towards red, and a dark shading towards violet. As 
dilution proceeds the shading first disappears, and then the dark portion 
of the band shrinks till its limits extend from about ~” 508 to A 486. 
After this the width of the band is constant, until with very large 
dilution it grows faint and ultimately disappears (Fig. 57, Spectrum 5). 
The activity of the pigment in absorbing light in this region is enormous, 
and a solution so dilute as to have a very faint colour indeed, will show 
a well-marked band. An absorption-band of an intensity such as is 
occasionally seen in normal urine, would correspond to that of an 
almost colourless solution of the pure substance. 

Urobilin, like most animal pigments, shows acidic tendencies, and 
forms compounds with bases, being liberated from these combinations 
on the addition of an acid. 

If ammonia be added to a solution of the free pigment, the colour 
changes to a canary-yellow, and unless the solution be very strong the 
absorption-band disappears. The sodium and potassium compounds 
have a colour in solution more like that of the free pigment, and show 
an analogous band, which is situate, however, somewhat nearer the red. 
The zine compound in ammoniacal solution fluoresces, as we have 
already stated, and shows with the spectroscope a band almost identical 
with that of the potassium and sodium compounds. The calcium com- 
pound is yellow in solution and shows no band. Mercury forms a pink 
compound, with a band nearer to the red than any of those previously 
referred to. A solution of mercuric chloride will develop a pink colour 


1 Garrod and Hopkins, Journ. Physiol., Cambridge and London, 1896, vol. xx. p. 120. 


622 THE CHEMISTRY OF THE URINE. 


when applied to tissues stained with urobilin, and may thus be used as 
a test for such staiming (Adolf Schmidt). 

When to a concentrated solution of nearly pure urobilin in sodic or 
potassic hydrate, sufficient sulphuric or hydrochloric acid is added to 
render the liquid faintly acid, a slight turbidity is observed, due to the 
liberation of the free pigment from its more soluble alkaline combination. 
If the turbid liquid be examined with the spectroscope, there is seen, in 
addition to the ordinary acid band between 0 and F, a sharply-defined 
narrow band in the green, enclosing, and being almost bisected by the 
Fraunhofer line E (Fig. 57, Spectrum 6). This extra band is most probably 
due to the special light absorption exercised by the impalpable particles of 
solid urobilin in suspension. It wholly disappears when the precipitate 
is filtered off, or when it is redissolved, the ordinary band alone being 
then visible. 

Solid urobilin is an amorphous red-brown substance, which, when 
isolated and dry, may be kept without decomposition. It is not 
deliquescent, but fuses at comparatively low temperatures, afterwards 
solidifying to a brittle transparent shellac-like form. It has a slight 
but peculiar and characteristic odour. 

Physiological relations—Urinary urobilin is identical with the chief 
pigment of feces (stercobilin). So certain is the identity of these two 
substances, that it is undesirable to retain separate names for them. 

Urobilin is closely related to the pigments of the bile. This was 
from the first recognised by Jaffé; and shortly after the discovery of 
the pigment, Maly prepared a substance (hydrobilirubin) by the 
reduction of bilirubin with sodium amalgam, which he held to be 
identical with urobilin. That the urinary pigment is a reduction pro- 
duct of bilirubin is lkely, but it is probable that hydrobilirubin, as 
described by Maly, represents an intermediate stage in the reduction. 
It differs at any rate somewhat from urobilin as it occurs naturally. 

Urobilin is formed, however, when bile decomposes out of contact 
with the air, and it may be extracted from the bile removed post- 
mortem from the gall bladder. 

Several observers have shown that intestinal micro-organisms can 
effect the reduction of bilirubin to urobilin. 


This pigment, or substances closely allied to it, can be prepared direct from 
hemoglobin derivatives—hematin and hematoporphyrin—by reduction pro- 
cesses. It has been stated that oxidation is also capable of yielding urobilin 
from bile and blood pigments respectively, but it is not conceivable that 
both reduction and oxidation could lead to the same chemical result, and there 
is in this matter an anomaly which requires explanation. It must not be 
forgotten that peroxides (peroxide of hydrogen and peroxide of lead, have 
been employed in this connection) may in a sense act as reducing agents, free 
oxygen being given off by the interaction of the peroxide and any easily 
reducible compound with which it is brought in contact. 


Urinary urobilin has not yet been analysed. If the formula of 
hydrobilirubin be compared with those of the related pigments, it will 
be seen that both reduction and hydration probably occur in its 
formation. 


Hematin : : . “C,H, oN,0,Fe 
Bilirubin : Gat NEO, 
Hydrobilirubin : TGR He ee 


1 Garrod and Hopkins, Journ. Physiol., Cambridge and London, 1896, vol. xx. p. 125. 


UROER VTHRIN. 623 


The change from bilirubin to hydrobilirubin may be thus ex- 
pressed-— 
C,9H3,N 0, + HO + Hy = Cy9H NO; 


If urobilin differs from hydrobilirubin, the difference is possibly, 
as already stated, in the direction of increased reduction. 

The origin of urinary urobilin is probably threefold—tfrom absorp- 
tion of the ready-formed pigment in the bowel; from direct production 
in the liver; and, lastly, from reduction of the blood pigment in the 
organs, independently of hepatic agency. 

Of the precise nature of the chromogen of urobilin we have no 
knowledge. It is precipitated intact when normal urine is saturated 
with ammonium sulphate in the absence of mineral acid. It is possible 
that oxidation may decompose it, as some urines originally showing 
no absorption-band will develop such on standing. This phenomenon 
might follow, however, from the decomposition during standing of 
some compound of the pigment with lime or other base. 

(c) Uroerythrin.—This pigment is best known as the colouring 
matter of pink urate deposits. It is a substance of the greatest interest, 
but one which has proved, from its marked instability, elusive and 
difficult of investigation. 

It was first dealt with as far back as 1800, by Louis Proust, 
under the name’ of acide rosacique. Its present name was assigned 
to it by F. Simon in 1850—the term “purpurin,” earlier proposed by 
Golding Bird, being still sometimes used. Heller published an account 
of the pigment in 1854, and Macmunn first accurately described its 
spectrum in 1883. Very important contributions to our knowledge of 
uroerythrin have recently been made by Riva, Zoja, and A. E. Garrod.” 

The quantity of the pigment excreted is, under any circumstances, 
very small; but its tinctorial power is extremely high, and when in 
solution it may materially contribute to the coloration of the urine. 
It is certainly to be looked upon as a pigment of normal urine, as 
urates coloured by it frequently separate from the excretion of persons 
in health. 


Separation.—A quantity of pink urate deposit is collected upon a filter, 
washed with ice-cold water, dried, and soaked in absolute alcohol. The 
alcohol, though a solvent for uroerythrin, does not extract it from the urates. 
The spirit is poured off and the precipitate dissolved in warm water; from the 
aqueous solution so obtained the pigment is easily and completely extracted by 
shaking with amylic alcohol (Riva). Garrod has shown that if the pink urates 
are first dissolved in warm water, and are then reprecipitated by saturation 
with ammonium chloride, the pigment is carried down with them afresh, and 
in such a condition that it may now be extracted with alcohol. An alcoholic 
solution, if diluted with water, may be washed by shaking with neutral 
chloroform, which removes impurities but no uroerythrin. But if after this 
preliminary washing a fresh supply of chloroform is added, together with a 
single drop of acetic acid, on shaking, the pigment is now found to be transferred 
completely to the chloroform as an effect of the acidification of the liquid. 


Properties—The most striking properties of uroerythrin are—(1) Its 
remarkable affinity for uric acid compounds; (2) the ease with which 
1 Hicholz, Journ. Physiol., Cambridge and London, vol. xiv. p. 326. 


2 Journ. Physiol., Cambridge and London, 1895, yol. xvii. p. 439. Full references to 
the literature will here be found. 


624 THE CHEMISTRY OP Di ORINE. 


its solutions are decolorised by light; and (3) its colour reactions 
with the caustic alkalies and mineral acids. The pigment invariably 
associates itself with urates during their precipitation ; either when they 
separate naturally from a urine “containing it, or when they are arti- 
ficially added to its pure solutions, and are allowed afterwards to separate. 


B. C. Dd, (Beli E G. 


B. C. Dd. Fees a G. 
Fic. 57.—Chart of spectra. 


. Acid hematoporphyrin. . The E band spectrum. 
Alkaline hematoporphyrin. . Uroerythrin. 
. Hematoporphyrin as found in urate sediments. | . Urorosein concentrated—on dilution the band 


Die Oo bo 
OID 


. Acid urobilin—concentrated. shrank rapidly from redward end. 
. Acid urobilin—dilute. 


It apparently forms a loose compound with the urates, as a special 
absorption-spectrum is seen when light passes through the pink pre- 
cipitate, differing from that proper to ‘solutions of the pigment (Garrod). 

The best solvent of uroerythrin is amyliec aleohol; acetic ether is but 
little inferior, and the pigment is also soluble in aleohol, chloroform, and 


H4MATOPORPH YRIN. 625 


water. The solutions have a rich orange colour; only when very dilute 
and quite free from impurity do they exhibit a pink tint. All solutions 
of the pigment are decolorised on exposure to light, even to subdued 
daylight. On the other hand, light has little effect upon the solid 
pigment, and none at all upon pink urate sediments. 

When solid uroerythrin is treated with solutions of the caustic 
alkalies, a remarkable green coloration is produced (Thudichum). Green 
derivatives from animal pigments are so uncommon that the reaction is 
highly characteristic. It can be well seen when a little pink urate 
deposit is collected upon a filter, dried, and then touched with a drop of 
sodium-hydrate solution. Ifa solution of the pigment be treated with the 
same reagent, a rapid play of colours may frequently be seen, from pink, 
through purple and blue, to grass-green. With acids, colour-reactions 
also occur, but they are somewhat less certain, being dependent upon 
exact conditions of experiment. If to a solution of the pigment 
sulphuric acid be added, the deep orange colour changes to a brilliant 
carmine. Hydrochloric acid produces a rose-pink, phosphoric acid a 
salmon-pink. 

Examined spectroscopically, a solution of uroerythrin, at a suitable 
degree of dilution, shows two somewhat ill-defined absorption-bands 
united by a shading of less intensity (Macmunn). The more red-ward of 
these is seen in the green between the lines D and E, and nearer the 
latter ; the other closely agrees in position with the ordinary urobilin 
band at F (Fig. 57, Spectum 7). Pink urate sediments and the carmine 
derivative produced by sulphuric acid agree in giving a single banded 
spectrum, namely, a broad band extending from the D line towards violet. 

(d) Heematoporphyrin. —In 1881, Ne eusser! and Macmunn? observed 
the occurrence in urine of pigments closely related to hematoporphyrin. 
During the following decade the work of le Nobel, Stockvis, Salkowski, 
Pemnarsten, Copeman, and others extended this discovery, and it 
became established that hematoporphyrin itself is a constituent of 
certain pathological urines. In 1892, A. E. Garrod*® showed that it 
is also to be found in normal urine. 

In health the pigment is excreted in very small amount, and can 
scarcely be said to function as an active colouring matter of the urine; 
but it is of the highest interest to recognise that this iron-free deriva- 
tive of hematin, which in the laboratory is only to be obtained by the 
use of strong reagents, is a normal physiological product. In patho- 
logical conditions, and especially after the use of certain drugs, it is 
present in greatly increased amount. 


Isolation from normal urine-—The method recommended by Garrod de- 
pends upon the fact that the pigment is carried down by the precipitate of 
phosphates produced on the addition of caustic alkali to the urine. After 
special treatment of this precipitate, the pigment may be obtained in chloroform 
solution. The chloroform is evaporated, and the residue washed with neutral 
alcohol and dissolved in acidified alcohol, when a solution is obtained of pure 
pink colour, comparable with solutions of the purest specimens of the pigment 
obtained from blood, and showing the spectrum of acid hematoporphyrin with 
distinctness. 


1 Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1881, Bd. lxxxiv. S. 536. 

* Proc. Roy. Soc. London, vol. xxxi. p. 206. % 
3 Journ. Physiol., Cambridge and London, 1892, vol. xiii. p. 598; ibid., 1894, vol. xvii. 
349. 


VOL. I.—40 


626 THE CHEMISTRVVOF VRAEVORINE. 


Pathological urines rich in the pigment will generally yield it easily to 
acetic ether and to amylic alcohol. 


Properties—An account of the properties of heematoporphyrin will 
be found in the section devoted to blood pigments; but the pigment as 
found in the urine has certain peculiarities which must be referred to here. 

When the urine is sufficiently rich in the pigment for the absorption- 
bands to be visible without treatment (always a pathological condition), 
it is found that the bands observed are those of the so-called alkaline 
hematoporphyrin (Fig. 57, Spectrum 2). Indeed, if a solution of the 
pigment showing the acid spectrum (but, of course, free from excess of 
mineral acid) be added to urine, the bands are seen to change to those 
of the alkaline form, even though the urine itself be of normal acidity. 
Acid sodium phosphate will, in fact, yield base to the heematoporphyrin, 
unless, indeed, the salt is in great excess, when it can, on the other 
hand, convert the alkaline form of the pigment into the acid. These 
facts form an interesting commentary on what we have said in the 
section devoted to the acidity of the urine, as to the complex conditions 
which govern the phenomena of chemical reaction in the fluid. 

Urinary hematoporphyrin may be in the form of unstable modi- 
fications. Alkaline solutions of the pigment obtained from many 
specimens exhibit a five-banded instead of a four-banded spectrum 
(Maecmunn). Occasionally, too, urate sediments may be pigmented with 
a form of the pigment which, in alkaline or neutral solution, shows ¢ 
spectrum of two bands resembling that of oxyhemoglobin (Fig. 57, 
Spectrum 3). Dilute mineral acids, however, promptly change this spec- 
trum to that of ordinary acid hematoporphyrin (Fig. 57, Spectrum 1). 
There is some evidence that a colourless chromogenic substance, related 
to heematoporphyrin, may occur in the urine, as the pigment has been 
observed to increase in amount after standing. 

Chromogenic substances in urine.—T'wo, at least, of the pig- 
ments we have now described (urobilin and heematoporphyrin) may 
exist, as we have seen, in the form of chromogens—colourless, or less 
coloured, precursors. But the urine contains other chromogenic sub- 
stances, which in the original urine always, or nearly always, retain 
their colourless form; and, as a rule, take no share in the true 
pigmentation of the fluid. 


We do not include, under the term of “chromogen,” all substances which, 
by the action of strong reagents, happen to be capable of yielding a coloured 
derivative. 

We purposely exclude such bodies as the so-called “ humous substances” of 
Udransky— indefinite products of wholly doubtful nature—obtained by such 
processes as fusing urinary precipitates with caustic alkali, or boiling the 
previously concentrated urine for hours with hydrochloric acid. These are 
probably derived from the carbohydrates and other constituents of the urine, 
by the destructive action of the reagents. Beyond the fact that they happen 
to be amorphous, and yellow or brown in colour, there is nothing to suggest 
that they are related to wrochrome or any other definite pigment. 


We shall deal only with those chromogenic substances which are of 
importance, either because they may, though with great rarity, appear 
as actual pigments, or because they yield their coloured derivatives 
with comparative ease, and may thus lead to confusion when the urine 
is being investigated in other connections. 


i -_ 


CHROMOGENIC SUBSTANCES IN URINE. 627 


(a) Indoxyl (indigo-blue and indigo-red).—Indoxy] (cf. pp. 607 
and 631) easily oxidises to indigo-blue, or to the isomeric substance 
indigo-red. The relation between indoxyl and its blue derivative is 
expressed by the following equation :— 


/ COW). BED sian Glo se ' 
eM” NcHons CHC nH Os Cy Ca + 20 


(indoxy]) (indigo-blue) 


The formula of indigo-red is CH iy C=C ct Wakes Ny, and it 


arises, like its blue isomer, when, by oxidation, four eas of hydrogen 
are removed from two molecules of indoxyl. Oxidising reagents when 
added to urine may, according to the conditions of the experiment, give 
rise to the formation of either or both of these coloured derivatives. 
The blue substance, however, is more easily and more generally 
obtained. 

It is of great rarity for the urine to be actually pigmented 
with indigo-blue. As we have already seen (p. 607), the urinary 
indoxyl is excreted in the form of a conjugated sulphate, and 
this compound resists oxidation. Only when the indoxyl is first 
liberated from its combination does the action of oxidising reagents 
produce the blue colour. It is stated, however, that the urine of 
cholera may sometimes exhibit a blue shade from the presence of 
indigo-blue. We have seen that the amount of indoxyl sulphate is 
increased in the urine whenever bacterial putrefaction of albuminous 
substances is occurring to a greater extent than usual, whether in the 
bowel or elsewhere in the body (putrid abscesses, etc.). The most 
ready method of demonstrating the amount of indoxy] is by converting 
it into indigo-blue. Jaffé’s test1—The urine is mixed with an equal 
bulk of strong hydrochloric acid, by which means the “indican” 
(indoxyl sulphate) is decomposed and the indoxyl liberated. Witha 
pipette, a solution of a hypochlorite is now added to the mixture drop 
by drop, when, by oxidation of the indoxyl, indigo-blue is formed. By 
shaking up the liquid with chloroform, a solution of the blue substance 
is obtained in the latter (Stockvis, Senator, and others). Otherwise, 
a crystal of potassium chlorate is placed at the bottom of a test tube 
and covered with the urine to be examined. Strong hydrochloric acid 
is then allowed to run down the side of the tube so as to reach the 
erystal without mixing with the urine. The latter floats upon the acid, 
and at the junction of the fluids a blue ring is seen of intensity varying 
with the amount of indoxyl present. 

But indigo-blue is itself an easily oxidisable substance. It is 
instantly decolorised by nitric acid, and without difficulty by hypo- 
chlorites. In Jaffé’s test, as above described, it is therefore necessary 
to add the oxidising agent with great care, or the blue colour will 
disappear as soon as formed. In Obermayer’s? method, the urine is 
first precipitated by acetate of lead, and filtered; to the filtrate is added 
an equal bulk of strong hydrochloric acid, containing two or three parts 
per thousand of ferric chloride. The mixture is shaken for a short 
time, and the liberated pigment taken up, as before, in chloroform. In 


l Arch. f. d. ges. Physiol., Bonn, 1870, Bd. iii. S. 448. 
2 Wien. klin. Wehnschr., 1890, S. 176. 


628 THE CHEMISTRY OF THE URINE. 


this case the ferric salt acts as a mild oxidising agent, sufficient to form 
but not to destroy the pigment. 

With care a certain amount of indigo-blue may be obtained from 
most normal urines; and, apart from the increase in actual disease, 
indoxyl may be present in considerable amount, and the urine yield 
a well-marked indigo reaction, when nothing more than constipation 
exists. 

Indigo-red is more liable to be formed from the urinary indoxyl 
when Jaffe’s test 1s applied with the aid of gentle heat. Higher 
temperatures favour the formation of the red isomer, lower tempera- 
tures the blue? In Weber’s test for indicanuria both pigments are 
formed. The urine is treated, as in other methods, with its own volume 
of hydrochloric acid: one to three drops of dilute nitrie acid are then 
added, and the mixture heated to boiling. After cooling it is shaken 
with ether, when the urine, if rich in indoxyl, is found to retain a blue 
colour, while the supernatant ether is red or violet. The formation of 
indigo-red has no significance beyond such as is attached to that of 
indigo- blue. It may ‘sometimes arise from the urine on the addition of 
strong hydrochloric acid alone (infra). 

(b) Urorosein. —Quite distinct from indigo-red is the red pigment, 
named “urorosein” by Nencki and Sieber,’ and since carefully studied 
by H. Rosin.t It is produced from its chromogen by the action of 
mineral acids ; best with the aid of an oxidising reagent, but frequently 
appearing when the urine is treated with strong hy drochlorie acid alone, 
especially after standing. It is freely taken up, after its formation, by 
amyl alcohol, but is not soluble in ether. Alkalies immediately destroy 
its colour. The chromogen of urorosein is precipitated by saturation 
with ammonium sulphate.® 


(c) Skatoxyl-red, w hich is formed from skatoxyl on oxidation, is never 
obtained from urine under ordinary circumstances (Rosin), though it may be 
produced in the urine of animals when skatoxyl has been given by the mouth 
(Brieger). 


It may be stated generally that when a red colour is produced in 
urine by the addition of strong acids (with or without the assistance 
of oxidising reagents), it will in the great majority of cases be due to 
urorosein or to indigo-red. The two pigments may be easily distin- 
guished, in that urorosein, unlike the indigo pigment, is not taken up 
on shaking with ether or chloroform, and is easily decolorised by 
alkalies.® 


THE PIGMENTATION OF PATHOLOGICAL URINES. 


All the pigments and chromogens that we have so far described may be 
excreted in increased amount in disease. There are other pigments which 
only appear in the urine pathologically. 

In the urine of fever a well-marked band of urobilin may generally be 
seen without preliminary treatment, and uroerythrin is often present in more 


1 Cf. v. Jaksch, ‘‘ Klinische Diagnostik,” 1896, Aufl. 4, S. 406. 

2 Rosin, Virchow’s Archiv, 1891, Bd. exxiii. S. 519. 

3 Journ. f. prakt. Chem., Leipzig. 1882, Bd. xxvi. S. 333. 

4 Deutsche med. Wehnschr.., Leipzig, 1893, S. 51. 

° Garrod and Hopkins, Journ. Physiol., Cambridge and London, 1896, vol. xx. p. 134. 
§ Rosin, Virchow’s Archiv, 1891, Bd. exxiii. S. 519. 


PIGMENTATION OF PATHOLOGICAL URINES. 629 


than normal amount. I have also frequently observed that urochrome itself 
takes a share in the increased pigmentation of febrile urine. 

Urobilin is found in large amount when extensive hemolysis, or large 
internal hemorrhages, have occurred; it is also greatly increased in certain 
eases of hepatic cirrhosis. The high colour of the urine of pernicious anemia 
is in part due to urobilin ; other pigments may take a large share in the increase 
in colour, but it is characteristic of this disease for free urobilin to be present 
instead of the chromogen, for even in pale specimens, which are sometimes 
passed, an absorption-band between J and F is usually visible. It is common 
for free urobilin to be present in diabetes. An increase of uroerythrin is 
seen in many forms of hepatic disorder. Haematoporphyrin does not appear to 
depend upon hemolysis for increased excretion. After excessive use of drugs 
of the sulphonal type, the urine may exhibit a deep port-wine colour; part, 
but not the whole, of this pigmentation is due to an enormously increased 
excretion of hematoporphyrin, which may be quite unassociated with any 
decrease in the hemoglobin of the blood. Increase of this pigment, but of 
much slighter degree, occurs also in plumbism and in certain other diseased 
conditions. 

The so-called pathological urobilin.—Several observers have made a 
distinction between normal urobilin and a pathological form of the pigment. 
The differences found have been mainly those of spectroscopic appearances ; the 
pathological form showing a proportionately broader band between 0 and F, 
and additional bands elsewhere. The various descriptions of the pathological 
pigment are in no sense consistent one with the other. Evidence has recently 
been brought forward to show that the points of distinction may be all 
explained as the result of impurities, and that urobilin is one and the same 
substance wherever found.! 

Special pathological pigments—Blood pigiments.—In hematuria, due 
to whatever cause, the urine usually contains unaltered hemoglobin. In 
general the pigment may be recognised in solution spectroscopically, while red 
blood corpuscles are found in the deposit. Some specimens of urine preserve 
the integrity of the corpuscles very completely, and in slight cases of hematuria, 
while no pigment may be found in solution, the deposit obtained by centrifuging 
will show a red layer of corpuscles. In hemoglobinuria the pigment is passed 
wholly in solution, and no corpuscles are found. Not infrequently methemo- 
globin is present in place of or in addition to oxyhemoglobin, even when 
the urine is first passed. Specimens which are spoken of as “smoky” usually 
contain this latter form of pigment. 

If the quantity of pigment is too small to show a recognisable spectrum 
direct, the urine may be heated with caustic alkali, filtered, and a few 
drops of ammonium sulphide added. The more powerful absorption-bands 
of hemochromogen will then be generally visible. Or, the urine may be 
boiled with caustic alkali, when, in the presence of blood, a greenish ‘tint is 
produced, and the phosphates are precipitated with a brownish-red colour, due 
to hematin (Heller). The blue colour produced by the addition of guaiacum 
tincture and an ethereal solution of hydrogen peroxide, is a delicate but not 
wholly conclusive test when applied to urine. 

Bile pigments appear in the urine in most cases of jaundice, generally in 
the form of bilirubin, when the urine is saffron-coloured ; but occasionally 
partly as biliverdin, when a greenish tint predominates. When present in 
large amount, there is no difficulty in the recognition of these pigments. 
Gmelin’s reaction is obtained by allowing the urine to run: gently on to the 
surface of some fuming nitric acid contained in a test tube. The test is made 
more delicate if the urine be first repeatedly filtered through a clean white 


1 Hopkins, Guy’s Hosp. Rep., London, 1893, vol. 1. p. 363 ; Garrod and Hopkins, ‘‘ The 
unity of Urobilin,” Journ. Physiol., Cambridge and London, 1896, vol. xx. p. 130, 


630 THE CHEMISTRY OF THE URINE. 


filter paper; the paper is stained yellow, and a drop of fuming nitric acid 
allowed to fall upon it produces the characteristic play of colours. When 
only traces of the pigment are present, Gmelin’s test is best apphed to the 
precipitate produced in the urine by the addition of lime-water with the 
subsequent passage of a stream of carbon dioxide ; the precipitate is filtered 
off, dried, and touched with nitric acid. 

Carboluria.—In poisoning by carbolic acid, and often to a less degree after 
the substance has been freely used as a drug, the urine has a greenish-brown 
or dark brown colour, which increases on exposure to the air. This colour is 
due to oxidation products of some of the aromatic substances present in normal 
urine, which have been dealt with on p. 607 ef seg. They are excreted in much 
greater quantity after the administration of phenol. Pyrocatechin and 
hydrochinon are especially responsible for the colour effect. 

Alcaptonuria (cf. p. 607).—A phenomenon very similar to that present in 
carboluria is seen in certain other conditions, where an alkaline urine, as it 
stands in the air, takes first a brown colour at the surface, which gradually 
spreads through the fluid, and may finally result in the whole urine becoming 
nearly black. Such urine always reduces copper solutions. The phenomenon 
was first observed by Boedecker in 1859, and it was later ascribed by him to a 
substance which he called alcapton. 

But alcapton, as already stated, is not a definite compound, and the colour 
phenomena are probably due to the action of oxygen upon some of the 
aromatic bodies present ; probably, at times, upon pyrocatechin and uroleuciec 
acid, but more often perhaps upon the homogentisic acid of Wolkow and 
Baumann (vide p. 606). 

Although thought to be especially frequent in various forms of tuberculosis, 
aleaptonuria must not be looked upon as specifically associated with any parti- 
cular diseased conditions ; it indicates rather some peculiar independent changes 
of metabolism, and is not infrequently met with in conditions of apparent 
health. In one case where there was a tendency for homogentisic acid to 
appear in the urine, it was found that the quantity of this substance and the 
associated colour phenomenon might be enormously increased by administering 
tyrosine, and it is suggested that, when homogentisic acid or other aromatic 
substances appear in excess, it is due to the action of special micro-organisms 
on the tyrosine of the bowel. 

Drug pigments.—The urine may contain purely accidental pigments due to 
the use of drugs, notably of rhubarb, senna, logwood, and santonin. 


THE INORGANIC CONSTITUENTS. 


To a large extent the inorganic constituents of the urine arise 
directly from the food, which always contains a large excess of salts. 
It does not follow, however, that the bases and acids are to be found in 
the urine in the same combinations as when ingested, and indeed an 
interchange of base and acid may occur in special circumstances between 
the salts of the food and those of the tissue fluids. Thus, excess of 
potassium in the food may lead to increased elimination of sodium 
(Bunge). The sulphates, moreover, form an exception to the general 
rule of direct origin from the ingesta, very small quantities of these 
salts being present in a normal dietary. The urinary sulphates are 
derived almost entirely from proteid metabolism ; a small proportion of 
the phosphates arising in the same way. 

Sulphuric acid and other sulphur compounds. —About 80 per 
cent. of the total sulphur in normal human urine is present in the 
fully oxidised form of sulphuric acid; from 2 to 2°5 grms. of the acid, 


SULPHURIC ACID AND SULPHUR COMPOUNDS. 631 


combined as salts, being excreted per diem. Two forms of salts exist— 
(1) the ordinary and strictly inorganic sulphates of the form M’,SO,, 
and (2) the so-called conjugated or ethereal sulphates, which contain 
organic radicles; the composition of these will be clear from what 
follows. 

If ordinary alcohol be boiled with its own bulk of strong sulphuric 
acid, under a vertical condenser, a crystalline product is formed which 
is known as ethylhydrogen sulphate, or sulphovinic acid. The com- 
position of this is explained by the following equation :— 


Coo OF. H—O H,O C,H.—O 
Sa 1 80st pas? ck so, 
/ 
Haas ae 
(alcohol) (sulphuric acid) (water) (ethylhydrogen sulphate) 


By elimination of water, the ethyl radicle (C,H; —) becomes “ con- 
jugated ” with the sulphuric acid, and a monovalent acid is formed, 
which yields salts of the type M’C,H,;: SO, On boiling such salts 
with hydrochloric acid, the sulphovinic acid is first liberated, and then, 
by absorption of water, splits up once more into alcohol and sulphuric 
acid. 

The “conjugated sulphates” of the urine are precisely analogous 
salts, which undergo like decomposition when boiled with HCl. But, 
instead of ethyl, the radicles conjugated with the sulphuric acid are 
nearly always derived from aromatic precursors. In fact, as we have 
already seen, most of the aromatic compounds of the urine described on 
p. 605 ef seg. are present as conjugated sulphates; and the proportion of 
the sulphuric acid present in this form depends upon the factors which 
increase or decrease these aromatic substances. The chief salts present, 
therefore, under ordinary circumstances, are those of kresyl- indoxyl- 
and skatoxyl-sulphuric acids. 

Normally, the sulphuric acid so combined amounts to about one- 
tenth of the whole; nine-tenths being in the form of ordinary sulphates. 
An increased proportion of ethereal sulphates is found when, for any 
reason, there is increase of proteid putrefaction in the body, and especi- 
ally in the bowel; and also when larger amounts of aromatic compounds 
than usual are taken by the mouth. In man they may be greatly in- 
creased during starvation, whereas, according to I. Munk, they are absent 
from the urine of a starving dog. 


For the detection and estimation of the sulphates we rely upon the forma- 
tion of the insoluble barium salt. All the sulphuric acid originally present as 
ordinary sulphates is precipitated as white crystalline barium sulphate, when a 
soluble barium salt is added to the urine, previously made acid with acetic acid. 
On the other hand, the barium salts of the conjugated sulphuric acids are soluble, 
so that when the barium precipitate, obtained as above, is filtered off, the 
ethereal sulphates still exist in the filtrate. But, as we have seen, they are 
decomposed on boiling with hydrochloric acid, splitting up into sulphuric acid 
and the hydrate of the: conjugated radicle. It is evident, therefore, that if the 
above-mentioned filtrate be so boiled with hydrochloric acid, a further precipi- 
tate of barium sulphate may be obtained, the amount of which will be a 
measure of the proportion of ethereal sulphates present. 


One-fifth of the total sulphur of the urine is present, not in any form 
of sulphate, but in less oxidised compounds. This fraction may be 
spoken of as the “neutral sulphur,’ in contradistinction to the “acid 


632 THE CHEMISTRY OF THE URINE. 


sulphur” of the sulphates.1 We have but little knowledge of the actual 
forms in which this neutral sulphur is excreted. As one source of the 
unoxidised sulphur compounds, we may look to the taurin of the bile, 
since it has been shown (in the dog) that when the bile is diverted 
from the bowel by means of a fistula, the neutral sulphur of the urine is 
diminished; experimental or pathological blocking of the bile duct, on 
the other hand, increases it. A second portion is probably present in 
a compound or compounds analogous to cystine,® and in actual cystinuria 
the neutral sulphur is, of course, greatly increased (ef. p. 603). 

Minute quantities of sulphocyanides are always present, probably 
owing to reabsorption from the saliva which is swallowed, and these 
contribute to the “neutral” sulphur.t But none of the sources we 
have mentioned will account for the whole of the unoxidised sulphur 
present, which must partly exist In compounds of which we have no 
knowledge. 


To estimate the neutral sulphur, a small quantity of the urine is evaporated, 
and the residue fused with alkaline carbonates and nitrate of potassium. By 
this means the whole of the sulphur present is oxidised to sulphates, and these 
are estimated as barium sulphate. A separate estimation of the sulphuric acid 
originally present is made, and the amount deducted from the figure obtained, 
as above. The excess is a measure of the neutral sulphur, in terms of sulphuric 
acid. 


Phosphoric acid.—The greater part of the phosphates of the 
urine is derived directly from those ingested with the food, but a small 
proportion arises from the oxidation of the nuclein, lecithin, and 
protagon of the tissues. The phosphates are increased by animal food, 
especially when this is rich in nucleo-proteids (Weintraud), and are 
diminished by vegetable diet. The phosphoric acid of plants is mostly 
present as insoluble earthy phosphates, which are not absorbed. On 
this account the urine of herbivora is notably poor in phosphates. In 
man the quantity is necessarily very variable, and ranges from 1 to 
8 grms. of phosphoric acid in the urine of twenty-four hours; it com- 
monly amounts to about 3°5 grms. 

The nature of the salts present has been fully discussed in the 
section devoted to the chemical reaction of the urine. Part of the 
phosphoric acid is present in combination with lime and magnesia, but 
a greater part is combined with the alkalies. Some importance has 
been attached to a change in the relative proportion of the “earthy ” 
and “alkaline” phosphates in diseased conditions, the estimation being 
made by adding ammonia to the urine and so precipitating the former. 
But the information so obtained may be misleading, as whatever the 
form of calcium or magnesium salt originally present in the urine (e.g. 
sulphates or chlorides), a precipitate produced by ammonia would contain 
these bases as phosphates, since an interchange of acids would take 
place with the alkaline phosphates. From alkaline urines magnesium 
ammonium phosphate (triple-phosphate) frequently separates in char- 
acteristic crystals; and in the deposit from feebly acid specimens 

1 Salkowski, Virchow’s Archiv, 1875, Bd. lviii. S. 472. 

? Cf. Kunkel, Arch. f. d. ges. Physiol., Bonn, 1877, Bd. xiv. S. 344. 


*Goldmann and Baumann, Zschr. f. physiol. Chem., Strassburg, 1888, Bd. xii. 
S. 254. 

* Leared, Proc. Roy. Soc. London, 1870, vol. xvi. p. 18; I. Munk, Virchow’s Archiv, 

1877, Bd. lxix. S. 354. 


‘ 


HVPROCTHLORIGC ACTD. 633 


ealcium phosphate is found in star-shaped masses of fine prisms (stellar 
phosphate) (Fig. 58). 


Pathologically, a diminution of the urinary phosphates is seen in nephritis 
(Purdy), and an increase is said to oceur in certain nervous diseases. The 
phosphates may be greatly increased in diabetes insipidus. 

For the estimation of phosphoric acid the urine is first treated with acetic 
acid and sodium acetate, and is then titrated with a standard solution of 
uranium nitrate. Ferrocyanide of potassium or cochineal tincture may be used 
as an indicator to mark the end point of the titration. 


Hydrochloric acid—There can be little doubt that the greater 
part of the hydrochloric acid of urine exists as sodium chloride, and it 


Fic. 58. . Stellar phosphates ; B. Triple phosphates. 


certainly arises mainly from the common salt present in the food. The 
tissues and fluids of the body maintain a very constant content of sodium 
chloride, any excess is at once excreted, and any diminution in the 
supply immediately reduces the excretion. The amount in the urine 
depends, therefore, in normal circumstances, almost entirely upon the 
quantity ingested, and falls to a mimimum during starvation, or when 
a salt-free diet is taken. Pathologically, striking alterations in the 
chlorides of the urme may be observed. Thus, whenever considerable 
exudations occur, as In pheumonic processes, or where pleuritic effusion 
is taking place, the consequent removal of chlorides from the blood may 
lead almost to a cessation of their excretion; and conversely, during the 
reabsorption of such exudations, the urinary chlorides may considerably 
increase, even when but little salt is being taken by the mouth. Apart 
from such exudations, fever appears to have a specific effect in pro- 


634 THE CHEMISTRY OF THE ORINE. 


moting a retention of chlorides; a fact for which we have no sufficient 
explanation.? 

Upon ordinary diet, about from 6 to 10 grms. HCl is excreted per 
diem by a healthy adult. 

To demonstrate the presence of chlorides, the urine is diluted, made 
acid with nitric acid, and mixed with nitrate of silver solution ; a white 
eurdy precipitate of silver chloride falls, which, if filtered off, is found 
to be soluble in ammonia. 


To estimate the hydrochloric acid, a known quantity of silver salt is added, 
together with nitric acid, to a measured amount of urine, taking care that the 
silver is in excess. The precipitate is filtered off, and the excess of silver 
titrated in the filtrate with a standard solution of ammonium thiocyanate, 
ferrous sulphate being used as an indicator. Knowing the amount of silver 
added, and that left in the filtrate, the difference indicates that combined as a 
chloride, from which the hydrochloric acid can be calculated (Volhard’s 
method). 


Carbonic acid is found even in acid urines; some 50 «cc. being 
present per litre.2 In acid urines the greater part is not in firm chemical 
combination, as it is driven out of solution by the passage of a stream 
of air. But when the urine contains abundant fixed bases, and especially 
when it is actually alkaline from these, considerable quantities of car- 
bonates may be present, the urine of herbivora being exceptionally rich 
in these. 


Nitric and nitrous acids may be present in normal urine in the 
form of salts, but in quite unimportant quantity. 

The nitrates are derived, not from metabolism, but directly from the 
food; the nitrites are not present when the urine is first passed, but 
appear to arise always from the nitrates, as an effect of the reducing 
action of micro-organisms. 

Silicic and hydrofluoric acids may appear in traces, simply as 
an effect of the presence of their salts in various foodstuffs. 

Sodium and potassium.—Of sodium about 5 grms. per diem is 
excreted upon a mixed diet, and of potassium about half this quantity. 
The proportion of the latter metal is increased when the dietary is more 
exclusively composed of flesh, and it is raised during starvation, and in 
febrile conditions.? We have already referred to the interesting fact 
that the ingestion of large quantities of potassium salts may lead to 
increased elimination of sodium from the body, and it is this driving out 
of the latter essential constituent of the body-fluids which makes the 
consumption of common salt with the food a necessity in all cases 
where the diet is rich in potassium.+ 

Calcium and magnesium.—In human urine, about 0-2 to 0'4 grms. 
of lime (CaO) is excreted per diem. 

Of the lime salts present in the food, only a small proportion is 
excreted by the urme. Mauch of the lime remains in an insoluble form, 
and is not absorbed at all, while of that which does enter the circulation 

1 Cf. Salkowski and Leube, ‘‘ Lehre vom Harn,” 1882, S. 174, 464, 465 ; see also Kast, 
Zischr. f. physiol. Chem., Strassburg, 1888, Bd. xii. S. 271. 

2 Wurster and Schmidt, Centradlbl. f. Physiol., Leipzig u. Wien, 1887, Bd. i. S. 421. 

3 Cf. Salkowski, Virchow’s Archiv, 1871, Bd. liii. S. 209 ; Munk, Berl. klin, Wehnschr., 
1887, S. 432. 

4 Bunge, ‘‘ Lehrbuch der physiol. Chem.” 


CHARACTERISTICS OF URINARY EXCRETIVES. 635 


a considerable fraction is re-excreted into the lower bowel. The 
administration of dilute mineral acids, which decomposes to some extent 
the insoluble phosphates of the food, increases the urinary lime salts, 
and, conversely, when sodium phosphate is taken in large quantities, the 
lime may almost disappear from the urine. 

Very interesting is the observation of G. Hoppe-Seyler,? who found 
that the excretion of lime salts by the kidneys is much greater during 
conditions of rest than during exercise, a fact which doubtless depends, 
in part at least, upon the effect of exercise on the excretion into the 
bowel. 

As a general rule, the urine contains about twice as much magnesia 
as lime.? Most food-stuffs, other than milk and eggs, contain more 
magnesium than calcium salts. The phosphates of the former are also 
more soluble, and as both bases are largely present as phosphates in the 
food, it is to be understood that more magnesium will be absorbed and 
excreted. When, as during starvation, the ingestion of magnesium salts 
ceases, the lime is found to be in the greater proportion. 


The presence of calcium in urine is easily demonstrated, and its amount 
determined by acidifying the fluid with acetic acid, and adding ammonium 
oxalate, when all the lime separates as the insoluble crystalline calcium oxalate, 
which may be filtered off and weighed as calcium carbonate, into which it 
is converted on gentle ignition. In the filtrate from this, the magnesium is 
precipitated as triple phosphate upon the addition of ammonium chloride, 
ammonia, and, if necessary, of some extraneous alkaline phosphate. 


Iron.—The urine contains, as a rule, a very minute quantity of iron, 
and frequently no detectable trace. It has been found increased in 
diseases, such as pernicious anemia, but never rises to more than a few 
milligrammes in the twenty-four hours. It is a remarkable fact that 
this metal, if present at all, is, toa large extent, precipitated in association 
with the pigmented crystals of uric acid, which separate when the urine 
is acidified with hydrochloric acid. It may be detected in the ash of 
large quantities of the urine, by taking a solution of this to dryness with 
a little nitric acid, dissolving the residue in water, and testing with 
potassium sulphocyanide, which gives with ferric salts a blood red 
coloration. 


GENERAL CHARACTERISTICS OF THE URINARY EXCRETIVES. 


It might perhaps be expected that the waste products of meta- 
bolism, on leaving the body, would in general represent the simplest 
compounds of physiological chemistry, and would stand farthest of all 
removed from the complexity of the tissue proteids. That this is not 
entirely the case, however, will have been clear from the facts set forth 
in previous sections; it is, indeed, striking to observe how many of the 
organic excretives arise by synthetic processes from simpler precursors 
in the body. 

There is one form of chemical change which takes an important and 


LVoit, Ztschr. f. Biol., Miinchen, 1892, Bd. xi. S. 387-397, where other references 
will be found. 

2 Ztschr. f. physiol. Chem., Stvassburg, 1891, Bd. xy. S. 161. 

3 Most analyses bear out this statement, but those of Bunge, given on p. 573, show an 
excess of lime. 


636 THE CHEMISTRY OF THE URINE. 


even dominant share in the processes of constructive metabolism: that, 
namely, of dehydrolysis—the synthesis of larger molecules by a con- 
jugation of smaller, associated with elimination of the elements of 
water. This process is known to chemists as one of “condensation.” 
In destructive metabolism, on the other hand, the converse process 
of hydrolysis is an important factor. 

While of most obvious importance in the physiology of plants, 
in which constructive metabolism starts from a lower chemical level, 
“condensation ” is also prominent in all constructive processes of which 
we have any accurate knowledge in the animal organism. Being thus 
in general so characteristic of assimilative processes, it is remarkable 
how frequently dehydrolytic synthesis interrupts the course of meta- 
bolic breakdown and reappears as a final step before excretion. 

We have dealt with a typical instance of this in the formation of 
hippuric acid from benzoic acid and glycine in the kidney, and we have 
seen that a like process occurs in the production of ethereal sulphates, 
and the conjugate compounds of glycuronic acid. We may note, too, 
that many substances introduced experimentally into the body undergo 
kindred conjugations before excretion. 

The theory of the origin of uric acid and the alloxuric bases from 
nucleins, does not perhaps predicate any synthetic step in the produc- 
tion of this group of excretives; but however far-reaching may be the 
truth of this theory, it must be admitted that there is much reason for 
ascribing the origin of at least some fraction of these substances, as 
found in the urine, to conjugative processes in the liver and kidney. In 
birds there can be little doubt that uric acid arises by a synthetic 
change. 

In the most important of the chemical changes antecedent to 
excretion—the formation of urea from ammonium carbonate in the 
mammalian liver—we have a process which I venture to think belongs 
essentially to the same chemical picture. Though not resulting, properly 
speaking, in a synthesis, the dehydrolysis which here occurs is a chemical 
change against the line of least resistance, and suggests an influence of 
the same type as that producing the synthetic results just discussed. 
Without misuse of the vague and somewhat discredited terms “ organic ” 
and “ inorganic,” we are entitled to look upon the dehydrolysis of am- 
monium carbonate as a return from the latter to the former category ; 
the excretive stands physiologically on a higher level than its precursor. 

To complete whatever of suggestion these considerations may contain, 
we may note finally the dehydrolysis which creatin suffers before ex- 
cretion as creatinin. Even here we meet with a change which, for the 
conditions under which it occurs, is one from a more stable to a less 
stable substance. 

It would seem that just before excretion there occurs an arrest of 
the normal processes of down-grade metabolism (in which hydrolysis 
goes hand in hand with oxidation, resulting in a series of compounds of 
increasing stability), and a brief return to dehydrolysis and to the type 
of constructive processes. It is at any rate interesting to observe that 
the renal excretives are as a class more complex or less stable than 
their immediate precursors in the body. When the urine decomposes, 
under the destructive influence of enzymes derived from  micro- 
organisms, many of the precursors reappear; the urea again becomes 
ammonium carbonate; hippuric acid and its analogues give place to 


COMPARATIVE CHEMISTRY OF THE URINE. 637 


benzoic acid, creatinin may again take up water, and uric acid is 
rapidly hydrolysed. 

The urinary nitrogen, it will have been observed, always appears 
either as ammonia (NH,), or more typically in compounds containing 
the derived amido (—NH,) or imido (= NH) groups. Compounds con- 
taining the other fundamental form of organic nitrogen, the cyanogen 
type (-C=N, or -N#=C), are represented only by the minute 
quantity of potassium sulphocyanide, which is in all probability directly 
derived from the saliva. Although a small proportion of the nitrogen 
is excreted in aromatic compounds, it is never, in human urine, present 
in the benzene nucleus of these, but always in side chains or accessory 
atomic groups within the molecule. 

The carbon ring of the benzene nucleus is especially resistant to 
oxidation in the body, the open chain of carbon atoms, proper to 
substances of the fatty series, being much less so; and for the most 
part we find that the normal renal excretives do not reach such 
molecular size as to contain as many as six carbon atoms, unless they 
contain the aromatic nucleus. As illustrating the degree of molecular 
complexity found in the organic urinary compounds, we may remember 
that the molecular weight of urea is 60, that of creatinin is 113, 
of uric acid 168, and of hippuric acid 181. The intact renal 
epithelium, it is’ true, passes substances, such as the pigments, the 
molecular weight of which is much greater than the above, but only 
in small quantities. 


COMPARATIVE CHEMISTRY OF THE URINE. 


In mammals, amphibia, fishes, and in certain molluscs, urea is the 
chief end-product of nitrogenous metabolism. In birds, reptiles, and 
arthropods, on the other hand, the nitrogen is excreted mainly in the 
form of uric acid. In spiders and in some few other groups of inverte- 
brates, the chief excretive has been shown to be guanin. 

A study of the renal function, from a comparative point of view, 
offers one aspect of great interest and some difficulty, to which Sir 
Wilham Roberts has called attention. It is remarkable that the wide 
differences in the nature of the renal excretion in mammals and the 
Sauropsida respectively, should yet be associated with almost complete 
identity in the anatomical structure of the kidney. The kidney of 
the bird has a glomerular mechanism identical with that of the 
mamimalhan organ, and the same tubular arrangement of a secretory 
epithelium ; and yet practically the sole function of the organ of the 
bird, in contrast to the remarkably complex duties performed by that of 
the mammal, is to secrete quadriurates. “The chlorides, phosphates, and 
sulphates, the lime and magnesia salts, the pigments and the large 
volume of water—all of which figure as prominent and even essential 
components of mammalhan urine—are either wholly absent from the 
urine of birds and serpents, or are only present in such minute traces 
as might be derived from the lubricating mucus and epithelial débris 
with which the secretion is incidentally admixed ” (Roberts). 

The physiological differentiation, whereby soluble urea takes the 
place of insoluble uric acid, in accordance with the needs of an 
organism excreting a liquid urine, is now known to occur quite at the 
final stages of metabolism. It is almost certain that, in the main, the 


638 THE CHEMISTRY OF THE URINE. 


waste products which leave the tissues are the same in birds and 
mammals. In the liver of the former these products are prepared for 
excretion by a change into the form of uric acid, while in the latter 
the hepatic influence produces urea. ‘There is a great preponderance of 
experimental evidence to show that when uric acid is administered to 
mammals it is converted into urea before excretion, and that when urea 
is given to birds the converse change occurs. The contention of Haig, 
that when uric acid is taken by the mouth (in man) it is excreted 
unchanged, is not supported by other observers. 

As to the small quantity of uric acid found, nevertheless, in the 
urine of mammals, if we accept the theory of its exclusive origi from 
nucleins, it is clear that we cannot look upon it as in any sense 
physiologically akin to the main part of the normal excretion of birds, 
for this must represent the waste nitrogen of the tissues as a whole. 
But this theory apart, the view is plausible, and indeed it cannot be said 
to be yet disproved, that we have in the mammalian uric acid a vestigial 
relic of the earlier type of excretion—*“ something analogous with the 
vermiform appendix, the ductus arteriosus, or the ear-point.’” The 
actual proportion present in the urine of different mammals is very 
variable. In most animals the relative amount is less than in man, but, 
except occasionally in the cases of the cat and dog, it has never been 
found to be absent. The presence of the small amount of uric acid in 
the urine of mammals is paralleled by the existence of minute quantities 
of urea in that of birds and reptiles. 

Creatinin has been found wherever looked for in the urine of various 
species of mammals, but is said to be absent from the excretion of birds. 

Hippuric acid is represented in birds by the analogous compound, 
ornithuric acid, which is a condensation product of benzoic acid with 
diamidovalerianic acid. An aromatic acid, apparently peculiar to the 
urine of dogs, is known as kynurenic acid, and has the composition of 
an oxychinolin-carboxylic acid (OH.C,H;N.COOH). 

The large proportion of hippuric acid in, and the absence of 
ammonium salts from, herbivorous urine, have been shown in previous 
sections to be, in common with the alkaline reaction of the fluid and 
its richness in salts, a direct effect of diet. 

Of the urinary pigments in the lower animals we have no accurate 
knowledge, 

It is impossible at present, owing to the wide gaps in our knowledge, 
to take any broad view of the comparative chemistry of the urine. A 
series of analyses are much needed, from the results of which we could 
form some judgment as to the line of evolution which has led from 
the simple renal excretions of the invertebrates to that most complex 
of physiological fluids —mammalhan urine. 


1See on the subject of the comparative chemistry of the urine, Rywosch, Wien. med. 
Wehnschr., 1893, Nos. 47 and 48. 


THE MECHANISM OF THE SECRETION OF URINE. 


By Ernest H. STARLING. 


ContTENtTs.—Theories of Urinary Secretion, p. 689—Theory of Bowman, p. 639— 
Theory of Ludwig, p. 640—Secretion of Water, p. 641—Methods, p. 642— 
The Concentration of the Urine, p. 650—Heidenhain’s Criticism of the Theory 
of Ludwig, p. 652—Experiments of Nussbaum, p. 655— Experiments of Ribbert, 
p- 656—Experiments of Bradford, p. 656—The Influence of the Nervous 
System on the Secretion of Urine, p. 659. 


THEORIES OF URINARY SECRETION. 


Ty all the organs of the body whose functions have been investigated by 
physiologists, it has been found that a difference of function is invariably 
associated with a difference in structure, so that the imterdependence 
of function and structure has become an axiom. We are therefore 
justified in founding theories concerning the physiological function of 
an organ on a purely anatomical study of its structure, although the 
complete establishment of such theories must ultimately be afforded 
by physiological investigations. 

The kidney differs from all other secretory glands, in the fact that 
at the blind end of its tubulus we find a structure—the glomerulus— 
where the vascular capillaries abut directly on the lumen of the tubulus, 
without the interposition of any lymph space. Ever since the publication 
of Bowman’s paper on the Malpighian bodies of the kidney, these have 
been looked upon as the essential source of the watery constituents of 
the urine. 

Theory of Bowman.—Bowman,! who founded his theory of urimary 
formation exclusively on the anatomical structure of the kidney in 
various animals, concluded that “as the tubes and their plexus of 
capillaries were probably the parts concerned in the secretion of that 
portion of the urine to which its characteristic properties are due (the 
urea, lithic acid, etc.), the Malpighian bodies might be an apparatus 
destined to separate from the blood the watery portion.” 

The following are the grounds on which Bowman based this 
hypothesis :— 

(a) That the tubes are secretory. 

(1) The extent of surface obtained by the involutions of the 
tubules. 

(2) The fact that the ming membrane of the tubules is formed 
by thick epithelial cells, similar to those found on the 
secreting surface of all true glands. 

1 Phil. Trans., London, 1842, p. 57. 


640 THE SECRETION OF ‘ORIVE: 


(5) The capillary network surrounding the uriniferous tubes is 
the counterpart of that investing the tubes of the testis, 
allowance being inade for the difference in the capacity of 
these canals in the two glands. 

(6) That the Malpighian bodies differ from the seereting parts of 

true glands. 

(1) The Malpighian bodies comprise but a small part of the 
inner surface of each kidney, there being but one to each 
tortuous tube. 

(2) The epithelium immediately changes its characters as the 
tube expands to embrace the tuft of vessels. 

(3) The blood vessels, instead of beimg on the deep surface of 
the membrane, “pass through it and form a tuft on its 
free surface.” 

(4) The peculiar arrangement of the vessels in the Malpighian 
tufts is clearly designed to produce a retardation of the 
blood through them, while the orifice of the tubule is 
encircled by cilia in active motion directing a current 
towards the tubule, so tending to remove pressure from 
the free surface of the vessels and to encourage the escape 
of their more fluid contents. “Why is so wonderful an 
apparatus placed at the extremity of each uriniferous 
tube, if not to furnish water to aid in the separation and 
solution of the urimous products from the epithelium of 
the tube ?” 

The appearance of this paper fell at a time when, led by Ludwig, 
Helmholtz, and du Bois Reymond, physiologists were endeavouring to 
replace the misty “ vitalistic ” conceptions which had until then prevailed, 
by an accurate comparison of vital phenomena with their physical or 
chemical counterparts, and seeking to establish physiology as an exact 
experimental science on a par with physics. It was impossible, therefore, 
that the views of Bowman, devoid as they were of experimental founda- 
tion, should remain unchallenged. 

Theory of Ludwig.—In 1844, Ludwig! put forward his well-known 
mechanical theory, for the establishment and testing of which a large 
volume of work has been done, the greater part under the direction of 
Ludwig himself. According to this theor y, all the energy for the secretion 
of urine is ultimately derived from the heart-beat. In consequence of 
the high pressure obtaining in the capillaries of the glomeruli, a fluid 
is filtered through, containing all the constituents of the urme in very 
dilute solution. This dilute solution passes down the tubules, and in its 
passage undergoes changes, in consequence of diffusion between it and 
the fluid (lymph) surrounding the tubules. Since water will always 
pass from a dilute to a more concentrated fluid, and since the glomerular 
filtrate is, according to the theory, poorer in solid constituents than 
the serum, water will pass from urine to lymph, and the urine will 
become more concentrated until it acquires the normal characters of 
urine. 

In this theory of Ludwig there are three distinct propositions to be 
investigated. These are— 

1. That the secretion of water is a purely mechanical process, 


1 Wagner's ‘‘ Handworterbuch,” 1844, Bd. ii. S. 637 ; ‘‘ Lehrbuch der Physiologie,’ 
Aufi. 2, 1858, Bd. ii. S. 373. 


SECRETION OF WATER. 641 


depending only on the blood pressure in the glomerular capillaries 
and the permeability of the filtering membrane. 

2. That this dilute urine is concentrated in the tubules by giving up 
its water to the surrounding lymph, in consequence of differences of 
concentration between the elomerular filtrate and the lymph. 

That all the urimary constituents are turned out of the blood 
iene the glomeruli (7.e. with the water) in dilute solution. 

In discussing the experimental data bearing on these propositions, 
we shall find ‘that only in the first part of the theory are the 
experimental facts consonant with Ludwig's hypothesis, and that it is 
impossible to explain the formation of normal urine without assuming 
the active intervention (i.e. the performance of work) by certain of the 
living elements of the kidney in the process. In this case, as in so 
many others in physiology, the “how” of the cellular activity is 
at present absolutely unknown to us, although we may confidently 
expect, with the advance of the science, to be able to trace the 
manner in which the cell utilises the energy of its food for this special 
purpose. 

Secretion of water.—One of the strongest facts in favour of Ludwig’s 
hypothesis is the indubitable 
connection which exists be- 
tween the circulation through 
the kidney and the amount 
of urine, 7.¢. of water, secreted. 
It is evident that a mechanical 
filtration or separation of the 
watery and crystalloid consti- 
tuents of the blood in the 
glomeruli must depend on two 


1. The difference of pres- 
sure between the blood in the 
glomerular capillaries and the 
urine in Bowman’s capsule. 
Since under normal circum- 
stances there is a free outflow 
of urine from the capsule by 
means of the tubules, we may 


regard its pressure as practi- 
éally Biase that the only 
thangeable factor in the pro- 
cess will be the blood pressure 
in the capillaries. 

2. The rapidity of the blood flow through the glomeruli must also 
have some influence on the filtration, as this process will go on the 
more readily the more often the fluid presented to the filter is renewed. 
As a rule, the changes that raise the pressure in the capillaries also 
increase the velocity of the blood through them, so that it becomes 
difficult to dissociate the part played by each factor in influencing the 
urinary secretion. 

If we consider the manner in which changes in the glomerular 
circulation are brought about, we see that it may be affected by changes 
either in the general blood pressure or in the calibre of the smaller 

VOL. I.—4I 


Fic. 59.—Roy’s oncometer. (For explanation of 
lettering, see next figure.) 


642 THE SECRETION OF “OKRINE. 


arteries. The pressure in the glomerular capillaries will be raised and 
the velocity of the blood increased— 

1. By a rise of general blood pressure. This may be due to— 

(a) Increased force or frequency of the heart beat ; 

(b) Constriction of vascular areas in other parts of the body. 

2. By dilatation of the renal arterioles, the general blood pressure 
remaining constant. 

3. By obstruction of the renal vein.: In this case the velocity will 
be diminished. 


Fic, 60.—Diagrammatic section through Roy’s oncometer, to show position 
of kidney. A, outer, and B, inner, brass capsules. These are fixed 
together by the screw C. G, the kidney. WD, a clamp for fastening 
the two halves together after the kidney has been inserted. XK, renal 
vessels and ureter. 


The pressure and velocity in the glomerular capillaries will be 
diminished— 

1. By diminished general blood pressure, which may arise from 
a weakening or slowing of the heart-beat, or from dilatation of vascular 
areas in other parts of the body. 

2. By constriction of the vessels in the kidney itself. 


Methods.—In the earlier researches! on the connection between the 
renal circulation and the flow of the urine, the observers had to content them- 


1Max Hermann, Sitzwngsb. d. k. Akad. d. Wissensch., Wien, 1859, Bd. xxxvi. S. 349 ; 
1861, Bd. xlv. S. 317 ; Ustimowitsch, Arb. a. d. physiol. Anst. zw Leipzig, 1870. 


—- 


_ During use, the space between 


METHODS. 643 


selves with a measurement of the general blood pressure, and could only 
obtain direct evidence as to the local changes in the renal circulation by 
inspection of the kidney. It was not until the ingenious application of 
plethysmographic methods to the kidney in situ, by Roy,! that we could 
obtain a precise and quantitative estimate of the changes produced on the 
circulation through this organ by the measures employed by the older observers. 

Roy’s instrument for registering changes in the volume of the kidney 
consists of two parts, in one of which, the oncometer, the kidney is placed, 
while another, called the oncograph, serves as the recording part of the 
apparatus. The oncometer consists of two halves hinged together, each of 
which is formed of two metal capsules screwed together by the screw C, and 
holding between them the membrane H. The two halves thus form a box. 
When the two halves are ap- 
proximated, the box is closed 
except at one point A, opposite 
the hinge, where there is an 
opening to allow the passage of 
the renal vessels and nerves, 
and the ureter to the kidney, 
which is placed within the box. 


the membrane and the metal 
box is filled with warm oil 
through the opening in the 
screw. The opening in one-half 
is then closed with a plug, 
while the other communicates 
by a tube £, with the onco- 
graph. It is evident that any 
change in the volume of the 
kidney will be communicated 
to the oil between the mem- 
brane and the capsule, oil being yg, 61.—Roy’s oncograph. Diagrammatic section. 
driven out into the tube #, The cylinder M is filled with oil, and com- 
when the kidney swells, and municates by the tube K with the oncometer. 
being sucked in directly any Chane i hs height of He ol are comm 


shrinking of the kidney oceurs. cursions of which serve therefore as an index of 
The oncograph, which is prac- the changes in volume of the kidney. 


tically a piston-recorder, in 

which the piston is made oil-tight by resting on a loose peritoneal membrane 
tied round the tube, serves to register the amount of oil driven out or sucked 
into the oncometer, and therefore at the same time the changes in the volume 
of the kidney. 

A simpler and more efficacious form of oncometer, in which air instead of oil 
is used, has been devised by Schafer? for the spleen, but is equally applicable 
to the kidney. A description of it will be found in the section dealing with 
the physiology of the circulation. 

Nerve supply.—Before discussing the effects of various operative 
procedures on the circulation of the kidney, it will be necessary to say a 
few words concerning the nerve supply to this organ, since its vessels, 
like those of all other parts of the body, are under the direct control of 
the central nervous system. . 

The gross distribution of nerves to the dog’s kidney has been the 
subject of a careful investigation by Nélner? in Eckhard’s laboratory. 


1 Journ. Physiol., Cambridge and London, vol. iii. p. 205. 2 Ibid., 1896, vol. xx, 
* Beitr. z. Anat. u. Physiol. (Eckhard), Giessen, 1869, Bd, iv. S, 139, 


644 THE SECRETION OF URINE. 


The course taken by the nerves is very variable. The nerves are derived 
from the sympathetic chain. From the ganglia lying on the head of the 
thirteenth rib, or from the cord immediately below this, is given off a 
large nerve (larger than the continuation of the sympathetic chain), 
which perforates the crus of the diaphragm, and is called the large 
splanchnic nerve. Between this ganglion and the next two or three 
gangha below, are given off three or four smaller filaments, known as the 
small splanchnic nerves. (It must be noted that this terminology is not 
comparable with that employed in human anatomy, where the term 
splanchnics is confined to the nerves given off by the sympathetic chain 
while in the thoracic cavity.) These large and small splanchnics form a 
plexus situated behind the suprarenals, and from which filaments are 
given off to the cceliac and superior mesenteric ganglia and solar plexus. 
From the plexus behind the suprarenals arise a number of filaments, 
which form a meshwork in the fat and connective tissues between the 
suprarenal and kidney, and then pass to the kidney around, and closely 
applied to, the renal artery. 

According to v. Wittich,! the renal nerves in the rabbit, dog, and man 
consist of two parts: one part of them forms a plexus closely investing 
the renal artery, while the other consists of several filaments which enter 
the kidney parallel to the vessels, and can be traced along these as far. 
as the cortex. 


The termination of these nerves in the kidney has been recently inves- 
tigated by Berkeley,” using Golgi’s method. He finds that from the vascular 
nerves fine filaments arise to be distributed throughout the cortical and 
medullary regions in the form of a vast open network. The glomeruli are 
surrounded by a wide-meshed plexus of fibres, having terminal end knobs, 
approximated closely to Bowman’s capsule, but not penetrating that membrane, 
nor passing to the glomerular capillaries. Fibres also pass off from the vascular 
plexus to be distributed upon the convoluted tubes, with terminations which 
penetrate the membrana propria of the tube, presumably to enter the cement 
substance between the epithelial cells. Berkeley looks upon these latter nerves 
as probably secretory in function. 


With regard to the connection of the renal nerves with the central 
nervous system, Bradford? has shown that, so far as the efferent nerves 
to the renal vessels are concerned, these leave the spinal cord through 
the anterior roots. Most of the fibres are contained in the eleventh, 
twelfth, and thirteenth dorsal nerve roots. 

Influence of blood flow on secretion of urine—We are now in a 
position to consider the influence exerted by changes in the circulation 
through the kidney on the secretion of urine. It must be remembered 
that a rise of general blood pressure does not necessarily carry with it an 
increased pressure in the glomerular capillaries or an increased blood flow 
through the kidney. Thus, under many conditions, a rise of general 
blood pressure is brought about by a constriction of all the visceral 
arteries, including those of the kidney, and such constriction is more 
than sufficient to counteract the effects of the increased blood pressure. 
If we take a tracing of the kidney volume, for instance, in asphyxia, we 


1 Konigsberger, Med. Jahrb., Wien, 1860, Bd. iii. S. 52 (quoted from Heidenhain in 
Hermann’s ‘‘ Handbuch”’). 

* Journ. Path. and Bacteriol., Edin. and London, 1893, vol. i. p. 406. 

* Journ. Physiol., Cambridge and London, 1889, vol. x. p. 358. 


INFLUENCE OF BLOOD PRESSURE. 645 


find, coincident with the rise of general blood pressure, a marked 
shrinking of the kidney. On the other hand, a dilatation of the renal 
vessels may be ineffectual to produce an increased flow through this organ, 
if at the same time there is a large fall of general blood pressure due 
to dilatation in other parts of the body. We may consider, in the first 
place, experiments in which the chief change has been in general blood 
pressure. It is found that, if the aortic pressure sinks below 40 mm. Hg, 
the urinary secretion stops absolutely. So long as the aortic pressure is 
above this height, the secretion is more or less proportional to the 
pressure, and changes with the changes in this pressure. Thus, if we 
stimulate the vagus in the neck, using currents sufficiently strong to 
produce a slowing of the heart-beat and a fall of blood pressure, there is 
a shrinking of the kidney and a diminution in the urimary flow (Goll). 
That this diminution in the flow is directly conditioned by the change in 
blood pressure due to the cardiac inhibition, is shown by the fact that 
stimulation of the vagi below the diaphragm is without effect on the 
urine (Eckhard). 

We may also alter the aortic pressure by bleeding the animal to a 
considerable amount, and later on reinjecting the blood so withdrawn. 
It is found that after the bleeding, while the blood pressure is diminished, 
-the flow of urine is also lessened, but the flow increases when the blood 
pressure is raised’ by reinjecting the blood which had been withdrawn. 

If the aortic pressure be raised by ligaturing a number of the larger 
arteries, the increased flow of blood through and the increased pressure in 
the kidneys are attended with increased secretion of urine. Thus in one 
experiment in which Goll! ligatured both carotids, both femorals, and 
both ascending cervical arteries, the urine was increased from 87 grms 
in 30 minutes before the ligature, to 21-2 grms. after the ligature, while 
the pressure in the aorta was raised from 127 to 142 mm. Hg. 

Division of the spinal cord.—lf the spinal cord be divided in the 
upper cervical region, the result is a great fall in general blood pressure, 
which may be as low as 30 to 40 mm. Hg. In all cases where the blood 
pressure falls below 40 mm. Hg, the flow of urine is absolutely abolished. 
Since the renal vessels, like those of all other parts of the body, are kept 
in a condition of tone by impulses descending from the vasomotor centre 
in the medulla, division of the path of these impulses must cause a 
relaxation of the renal vessels, which by itself would tend to occasion 
increased blood pressure in the glomeruli. As a result of the section, 
however, the vessels all over the body are relaxed, so that the capacity of 
the vascular system is increased and the peripheral resistance diminished, 
both factors concurring to produce the large fall of pressure observed. 
This fall of pressure is more than sufficient to counterbalance the local 
renal dilatation, so that there is diminished blood flow through the 
kidney, as is shown by the marked shrinking of the oncometric curve of 
the kidney on section of the cord. 

Stimulation of the cord4—If the peripheral end of the divided cord be 
stimulated with an induction current, universal constriction of the blood 
vessels and a large rise of blood pressure are produced. This, however, 1s 
incompetent to bring back the urinary flow which has been abolished by 
the previous section, since the renal vessels concur in the general con- 
striction, and the kidney shrinks still further in spite of the raised blood 
pressure. If, however, this local constriction be prevented by previous 

1 Ztschr. f. rat. Med., 1854, N. F., Bd. iv. S. 86 (quoted by Heidenhain). 


646 THE SECRETION OF URINE. 


division of all the renal nerves, stimulation of the cord causes a large 
expansion of the kidney and brings back the urinary flow. 

Influence of the splanchnics—tThe effects of stimulating the splanch- 
nic nerves are very similar to those obtained from the stimulation of the 
cord. Asin the latter case,a large rise of general blood pressure is 
produced, but the constriction of the renal vessels more than counteracts 
the effects of this rise, so that the kidney shrinks and the flow of urine 
is diminished or abolished. The effects of dividing the splanchnics vary 
in different animals. In the rabbit, where, in consequence of the extent 
of the vascular area supplied by this nerve, a considerable fall of general 
blood pressure is produced, no increase in the urinary secretion is 
observed. In the dog, on the other hand, the lasting effect on the aortie 
pressure is insignificant, so that the relaxation of the kidney vessels 
caused by the section induces a largely increased flow through this organ, 
and a marked increase in the flow of urine. 

Influence of renal nerves.—Division of the renal nerves on one side 
causes vasomotor paralysis in the organ of that side. The kidney there- 
fore swells, and the flow of urine is increased. The swelling and 
secretion is still further increased if the general blood pressure be ‘Taised 
by stimulation of the splanchnics or spinal cord. Stimulation of the 
renal nerves causes constriction of the vessels and diminished flow of 
urine. 

Bradford? has brought forward evidence to show that vaso-dilator 
fibres run to the kidney with the constr ictors, in the eleventh, twelfth, and 
thirteenth dorsal nerve roots. If the anterior roots of these nerves be 
stimulated with induction shocks, repeated at the rate of one per second, 
the effect is often a marked swelling of the kidney without any rise of 
blood pressure sufficient to account for the enlargement. A similar 
active dilatation of the vessels may be brought about reflexly by stimulat- 
ing the posterior roots of these nerves. We have no direct experimental 
evidence as to the influence of this active vascular dilatation on the 
renal secretion, although it is extremely probable that a similar condi- 
tion is the chief factor in the production of the extreme hydruria met 
with in hysteria and other nervous affections. , 

Constriction of renal artery.—In some of the earliest researches on the 
connection between the blood flow through the kidney and the urinary 
secretion, it was sought to affect the circulation by direct mechanical 
constriction of the renal artery. Hermann,? who carried out experi- 
ments of this nature under Ludwig’s guidance, showed that when the 
artery was constricted to a considerable extent, the result was a dimin- 
ished flow of urme. If the constriction were carried so far that the 
circulation of the kidney was entirely stopped, the flow of urine instantly 
ceased. So far these results are those one would expect on. the filtration 
hypothesis. It is found, however, that the flow of urine is not restored 
at once on relieving the constriction, and that after a few minutes’ total 
cessation of the renal circulation, more than an hour may elapse between 
the restoration of the circulation and the recommencement of the secre- 
tion. We have seen that in the case of lymph formation, where a 
process of filtration almost certainly comes into play, a temporary - 
ischemia increases the permeability of the vessel wall, so that, on the 


1 See especially Eckhard, Beitr. x. Anat. u. Physiol. (Eckhard), Giessen, 1869, Bd. iv. 
S. 132, and 153-193. 
* Loc. cit. 3 Loc. cit. 


ACTION OF DIURETICS. . 647 


subsequent restoration of the blood flow, the amount of lymph transuded 
is greater than before the ligature. In the kidney the reverse is the 
case. A temporary ischemia abolishes the flow for a considerable period 
after the obstruction has been relieved. This fact shows that, for the 
normal production of urine, the integrity of the living cells between the 
blood and Bowman’s capsule is necessary; but I do not think that it 
can be looked upon as definitely proving the active co-operation of these 
cells in the process. In the kidney we have two layers of cells, the 
vascular endothelium and the glomerular epithelium, intervening between 
the blood and urinary tubule, and we have no evidence to guide us as to 
the effects of temporary ischemia on the glomerular epithelium. We 
know that in a certain sense it becomes more permeable, inasmuch as 
the ure which is first secreted after the restoration of the circulation 
contains albumin, which may be traced on its way through the glome- 
rular epithelium into the capsule. But this fact in itself might tend to 
impede the flow of water through the glomerular membranes. 

Ligature of renal vein—tIn the case of lymph formation, a rise of 
venous pressure tends to increase the amount of lymph produced. In 
the kidney, ligature of the renal vein stops the flow of urine at once, 
although it must send up the pressure in the glomerular capillaries to a 
height approaching that of the renal artery. Now, in this case there are 
three factors which might be concerned in causing the cessation of 
secretion: the blood flow through the kidney is checked; the cells of 
the glomerular epithelium are asphyxiated; and the engorgement of the 
renal veins causes the interlobular veins to swell up and press on the 
adjoiming collecting tubules. Heidenhain lays most stress on the first 
factor, and, relying mainly on this experimental result, concludes that 
the chief agent in exciting glomerular activity is not the blood pressure 
in the glomerular capillaries, but the rapidity of the flow through the 
capillaries. On the other hand, Ludwig has shown that the effect of the 
swelling of the interlobular veins is to obstruct the urimary tubules; and 
he looks upon the cessation of flow as entirely due to this mechanical 
obstruction. It is impossible at present to decide which of these 
explanations is correct, or indeed whether all of them may not be 
involved. 

Action of diuretics—Since the main office of the kidney is to. assist 
in maintaining the normal constitution of the blood by freeing it from the 
waste products of tissue metabolism, we should expect it to react and to 
be sensitive to slight changes in the composition of the blood. Asa 
matter of fact, we find that such is the case, and that the easiest way to 
excite the urinary flow is by altering the composition of the blood, 
through the administration of large quantities of water, or of certain 
drugs which are known as diuretics. Of these bodies the only ones we 
need discuss are the large class known as saline diuretics and the drugs 
caffein and digitalis. 

Saline diuretics include practically all crystalloid substances, which 
can be injected into the blood in considerable quantities. As examples, 
we may. cite urea, dextrose, sodium chloride, potassium nitrate, sodium 
acetate, etc. If these bodies be injected into the blood, a very copious 
secretion of urine is soon evoked, even if, previously to the injection, 
the secretion had been at a standstill. In experiments on the excised 
kidney, it has in most cases been found necessary to add urea or some 
other substance of this group to the defibrinated blood used for the 


648 THE SECRETION OF URINE. 


artificial circulation, before any secretion could be obtained On 
Inquiring into the mode of action of these bodies, we find that their 
injection is followed by a slight rise of blood pressure accompanied with 
a marked expansion of the kidney, and this expansion lasts throughout 
the period of increased urinary flow. These effects are observed even 
after all the renal nerves have been severed, so far as is practically 
possible, and it has therefore been concluded that the changes in volume 
of the kidney must be due to the substances acting either upon some ~ 
peripheral vasomotor mechanism, or even more directly upon the blood 
vessels themselves. Since the increased secretion of urine is cotermin- 
ous with the increased blood flow through the kidney, it is natural to 
place these two events in the relation of effect and cause. To this con- 
clusion it has been objected that one may frequently observe an absolute 
standstill of secretion, with a high aortic blood pressure changed into a 
copious secretion by the injection of one of these bodies, although the 
blood pressure has been practically unaltered. Heidenhain and others 
with him, therefore, look upon the action of these bodies as secretomotor. 
Against the specific secretomotor action, either of urea or of the salines, 
the following arguments may be brought forward. V. Limbeck? has 
shown that the power of these bodies to induce urinary secretion on 
injection into the blood stream is proportional to their power of attracting 
water ( Wasseranziehungsvermégen), and is thus a function of their mole- 
cular weights. Now it has been proved ® that the result of injecting these 
bodies into the blood is to cause an active flow of water from the tissues 
into the blood, which therefore becomes diluted to an extent varying with 
the osmotic pressure of the substances injected. The final effect, there- 
fore, is the same as if a solution of the substance isotonic with or normal 
to the blood had been injected into the circulation, and a condition 
of hydremic plethora thus induced. We know that a condition of 
hydremic plethora is associated with dilatation (especially of the visceral 
vessels), general rise of capillary and venous pressures, and increased 
rapidity of blood flow. The fact that the diuretic action of these bodies 
is proportional to their osmotic pressures, implies that it is also propor- 
tional to the hydremie plethora produced by the injection ; and it seems 
probable, therefore, that the plethora is the chief agent in causing, first, 
the vascular changes in the kidney, and secondly, the diuresis. If these 
bodies acted as specific stimulants of the kidney, we should expect the 
increased flow of urine to continue until all the substance injected had 
been excreted. Such, however, is not the case. The diuresis comes to 
an end when only a small amount of the injected substance has been 
excreted, and lasts little or no longer than the hydreemie plethora which 
accompanies it. . 

Of the other diuretics, the action of two, caffein and digitalis, has been 
very fully investigated. If half a grain of caffein be injected into a vein, 
the kidney after a few seconds diminishes in volume, and the flow of urine 
is lessened or entirely arrested. This contraction soon passes off, and is 
followed by a rapid expansion, which is more considerable and lasts much 
longer than the preceding contraction. Simultaneously with the beginning 

1M. Abeles, Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1883, Bd. lxxxvii. ; I. Munk, 
Virchows Archiv, 1886, Bd. cvii. S. 291; ibid., S. 187; and I. Munk and Senator, 
tbid., 1888, Bd. exiv. S. 1. 

2 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1889, Bd. xxv. S. 69. 


° V. Brasol, Arch. f. Physiol., Leipzig, 1884, S. 211; Starling, Journ. Physiol., Cam- 
bridge and London, 1894, vol. xvii. p. 30; Leathes, ibid., 1895, vol. xix. p. 1. 


LIGATURE OF THE URETER. 649 


of the expansion, the urinary flow recommences and becomes much more 
rapid than it was previously to the injection of the drug. On the general 
blood pressure the injection of caffein causes an initial slight fall, followed 
by a return to normal or a little above normal. In this case we seem to 
be dealing with a drug, the most important action of which is on the 
renal vessels, and it is probable that the increased pressure in and flow 
through the glomerular capillaries induced by the drug is largely 
responsible for the augmented flow of urine. According to von 
Schréder,! it is possible, by the administration of chloral, to abolish the 
vaso-dilator effect of caffein in rabbits without destroying the diuretic 
action of the drug; but too much reliance cannot be placed on this 
statement, since the volume of the kidney was not measured in this 
observer's experiments. 

The effect of digitalis is rather more complex. It slows and 
strengthens the cardiac beat, and at the same time constricts the smaller 
arteries of the body, so that the arterial pressure is raised. In heart 
disease the result of the improved working of the cardiac pump is to 
relieve the venous pressure, increase the arterial pressure, and so bring 
about an improved blood flow through the kidney. In such cases, there- 
fore, digitalis acts as a powerful diuretic. In the healthy animal the 
effect of this drug is more doubtful. It causes a constriction of the 
renal vessels and therefore a shrinking of the kidney. Under certain 
circumstances, however, it does exert an appreciable influence in causing 
diuresis, which we may either explain, with Bradford and Phillips,’ 
as due to a direct action of the drug on the renal epithelium, or to the 
fact that the rise of blood pressure more than counteracts the renal 
constriction, so that there is an increased blood flow and pressure in the 
glomerular capillaries. 

Effects of ligature of the ureter——If we are to look upon urine as a 
filtrate, the amount of it must vary as P—p, where P represents the 
pressure in the glomerular capillaries, while p represents the pressure at 
the beginning of the urinary tubule. So far, we have only considered 
the effects of altering P, and have seen that, in the majority of cases at 
any rate, the secretion of urine rises and falls with this pressure. Under 
normal circumstances p is so small that it may be neglected, but we 
ought to be able to diminish the flow of urine by increasing p. IH the 
ureter be obstructed by connecting it with a mercurial manometer, it 
will be found that the mercury in the manometer rises quickly to 10 or 
20 mm. Hg, and then more slowly until, in the dog, it may attain the 
height of 50 or 60 mm. Hg, at which pressure the mercury column 
remains stationary. The pelvis of the kidney and the ureter above the 
ligature are now strongly distended; the kidney is swollen, and a marked 
cedema is soon observed extending to the perinephritic tissues, while 
the lymphatics of the hilus are distended with clear fluid. Some hours 
later, hemorrhages are found in the fatty capsule and in the pelvis and 
ureter. Ludwig interpreted these results as determining the conclusions 
he had already drawn from the effects of section of the spinal cord, «.c., 
that, for the production of urine, a certain minimum difference of 
pressure P—p is necessary, and that the difference might be reduced 
below this limit either by diminution of P or by augmentation of p. 


1 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1887, Bd. xxii. S. 39; 1888, Bd. 
xxiv. S. 85. 
2 Journ. Physiol., Cambridge and London, 1887, vol. viii. p. 117. 


650 THE SECRETION OF URINE. 


Heidenhain, however, points out that we have no right to conclude that 
the secretion of urine has ceased when the mercury column no longer 
rises. This stage in fact corresponds merely to the point at which the 
continued secretion of urine is balanced by the reabsorption of the urme 
from the tubules, in consequence of the abnormal pressure within 
them. 

It must be confessed that we have no very definite evidence that 
such a reabsorption takes place. It is true that the kidney becomes 
cedematous in consequence of the ligature, but the cedema fluid was stated 
by Ludwig to consist of lymph and not of urine; and it has been shown 
that increased pressure in the urinary tubules causes them to press on 
the adjoining veins, so that the escape of blood from the kidney is 
hindered, and ordinary cedema results. Fresh investigations on this 
matter are much to be desired, since the only analyses we have of the 
cedema fluid and retained urine are those of Hermann, one of the earliest 
observers on the subject. The urine, which is secreted under pressure 
and which distends the pelvis and ureter, is light in colour, of low 
specific gravity, and contains very little urea. If, after some time, the 
ligature round the ureter be relaxed, the result is at once a copious 
secretion of watery urine. In mana similar fluid is well known to be 
excreted in cases where there is a chronic obstruction of the ureter. 

The concentration of the urine.—We have now to consider the 
second part of Ludwig’s theory, according to which the dilute urme 
transuded through the glomeruli is concentrated on its passage down 
the tubules, by the absorption of its water. This absorption takes place 
in consequence of the fact that the lymph surrounding the tubules is 
more concentrated than the urine. A cogent objection to this hypo- 
thesis was raised in 1859 by Hoppe (Hoppe-Seyler), who showed that, 
if urine were separated by an animal membrane from blood serum otf 
the same animal, there was a flow of water from serum to urine The 
tendency of this urine, therefore, in passing down the urinary tubules, 
would have been to become more dilute, in consequence of osmotic 
interchanges between it and the serum. At this time our knowledge 
of the factors and forces involved in the interchange of water and sub- 
stances in solution across animal membranes was meagre and inexact ; 
and it is only quite recently that we have acquired the necessary data 
for testing the truth of Ludwig’s hypothesis and the fitness of Hoppe- 
Seyler’s objections. 

Pfeffer? showed that the osmotic attraction of any solution for water 
might be determined by measuring its osmotic pressure, and first pointed 
out how enormous these pressures were in the case of even relatively 
dilute salt solutions. Van t’ Hoff later on pointed out that the osmotic 
pressure of a solution was proportional to the number of molecules this 
contained, and was therefore a colligative property (Ostwald), like certain 
other properties of solutions—such as the diminution of the freezing 
point and of the vapour tension and the elevation of the boiling 
point. 

Since these properties of a solution are proportional to one another, 
we need only know one to determine any of the others. This fact is of 
importance when we wish to determine the osmotic pressure of animal 
fluids, since we can substitute for the difficult and inexact determination 


1 Virchow’s Archiv, 1859, Bd. xvi. S. 412 (quoted by Heidenhain). 
2 *“Osmotische Untersuchungen,” Leipzig, 1877. 


OSMOTIC PRESSURE OF URINE. 651 


of osmotic pressures by Pfeffer’s method a determination of the freezing- 
point of the solution. As van t’ Hoff has shown, if A is the depression of 
freezing-point and 7’ the absolute freezing-point of the solvent (ae., for 
water, 273°, and w the latent heat of fusion of ice=79 cal.), then the 
work A can be reckoned from the following formula :— 


Aw 


dA= x dv. 


Thus for 1 per cent. solution of cane-sugar (A=°055) 


dA a 02919 
7 


2 


x dv. 


To reduce this result to gravitation units we must multiply by 424, 
and we thus find that to separate the volume dv of pure water as ice 
from 1 per cent. cane-sugar solution, a force is necessary equal to the 

‘055 K 79 x 424 


273 


pressure of a column of water of metres in height. 


A depression of A= —1° corresponds therefore to an osmotic 
19 x 424 


pressure of 273 


; that is to say, to 122°7 metres of water. We 
have therefore to multiply A by 122'7, in order to obtain the osmotic 
pressure in metres of water of any solution. 

Now it is evident that, according to Ludwig’s hypothesis, the osmotic 
pressure of the urine might attain to but could never exceed that of 
the blood plasma. On estimating the osmotic pressures of these two 
fluids, we find that, under normal circumstances, the osmotic pressure of 
the urine is considerably greater than that of the blood, so that work 
must have been done in the separation of this concentrated fluid from 
the more dilute blood plasma. Dreser! has estimated this work ina 
case in which, during one night, 200 c.c. of urine were secreted with 
A=2°3. This was separated by the kidneys from the blood with 
A= 56. In the production of this fluid Dreser finds that the work 
done by the kidney amounts to 37-037 kilogramme metres. This figure 
by no means represents the maximum force which can be exerted by the 
kidney. From a cat which had been deprived of water for three days, 
Dreser drew off some urine with A=472 C. The blood at the same 
time had an osmotic pressure corresponding to A=0°66 C. These 
differences in freezing point denote an osmotic difference of 498 metres 
water, 7c. a pressure of 49,800 grms. per square centimetre. If this 
work of concentration were carried out by the cells of the tubules, 
these results would imply that these cells can exert a force six times 
greater than the absolute force of human muscle (8000 grms. per square 
centimetre). 

Assuming that the whole work of the tubules is confined to the act 
of concentration, Dreser seeks, moreover, to demonstrate that the 
glomerular secretion also involves the activity of living cells. Since 
the blood pressure of 200 mm. Hg=2'72 metres water, and A 1°0 C.= 
122-7 metres water, the highest possible difference between dilute urine 
and blood, assuming that no concentration had taken place, could only 
be A=0°022 C. Dreser finds, however, that after beer drinking, and 

1 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1892, Bd. xxix. S. 307. 


652 THE SECRETION OF URINE. 


in diabetes insipidus, the urine secreted may have A=0°16 C., te. a 
difference between A of blood and of urine of ‘4° C. Hence he con- 
cludes that the production of urine by the glomeruli is also attended 
with the doing of work, and must therefore be looked upon as a process 
of secretion. We might, however, still adhere to the theory of glomer- 
ular filtration, if we e assumed either that the cells of the tubules could 
absorb water or solids according to the needs of the organism, or that 
they were able to secrete pure water and so dilute the glomerular 
transudation. 

Heidenhain’s criticism of the theory of Ludwig.—The difficulties 
in the way of accepting Ludwig’s hypothesis have led Heidenhain, after 
a long series of researches on the subject, to reject this theory abso- 
lutely, in favour of one very similar to that put forward by Bowman. 

Heidenhain sums up his objections to the mechanical theory under 
the following headings :— 

i. The hypothesis that a rise of arterial pressure causes increased 
transudation through the vessel walls, is not confirmed by our experience 
in other parts of the body (lymphatics of the limbs, salivary glands). 

2. This hypothesis is rendered the more improbable for the kidney, 
since in this situation the glomerular capillaries are covered by a second 
layer of epithelium, and we know, from Leber’s researches on the cornea, 
that such a simple epithelial layer can afford great resistance to 
filtration. 

If we assume that all the constituents of the urine are filtered 
off in the glomeruh, the small amount of urea in the blood renders it 
necessary that in man about 70 kilos. of fluid should be filtered through 
and reabsorbed, in order that the urea produced in the course of 
the day may be excreted in the urine —an amount which is highly 
improbable. 

4. According to the filtration hypothesis, the amount of urme formed 
must always increase with increased capillary pressure, whereas we find 
that, on increasing capillary pressure by ligature of the renal vein, the 
urinary flow is abolished. 

The hypothesis that the glomerular transudate is concentrated by 
a sities of osmosis or diffusion, on its way through the glomeruli, is 
rendered impossible by the fact that the osmotic pressure of the 
urine may be, and generally is, much higher than that of the lymph 
or blood. 

6. The filtration hypothesis does not explain why the amount of 
urine is increased by the presence of water or crystalloid (harnfahig) 
substances in the blood. 

From his own researches on the subject, Heidenhain comes to the 
following conclusions with regard to the mechanism of secretion :— 

1. In the kidney, as in all other glands, the secretion depends on the 
active intervention of special secretory cells. 

2. The first type of these cells is represented by the simple layer 
of epithelium covering the glomerular loop of capillaries. The office of 
these cells is to secrete water and such salts of the urine as are found 
in all other parts of the body in watery solution (e.g. sodium chloride). 

3. Another system of secretory cells, forming the lining investment 
of the convoluted tubules and ascending tubule of Henle, secrete the 
specific constituents of urine (urea, uric acid, ete.). Under some con- 
ditions they may at the same time secrete a certain amount of water. 


HEIDENHAIN’S THEORY. 653 


4, The activity of the two kinds of secretory cells is determined— 

(a) By the amount of water or urinary constituents contained in the 
blood ; 

(b) By the velocity of the blood-flow through the capillaries of the 
kidney, inasmuch as on this factor depends the supply of oxygen, and 
of substances to be excreted, to the cells. 

5..The great variability in the constitution of the urine may be 
explained by differences in the secretory activities of these two types of 
cell. 

The most important part of these conclusions of Heidenhain is a 
revival of Bowman’s theory, that the specific urinary constituents, urea 
and uric acid, are secreted by the tubules, and that the office of the 
tubules is secretory rather than absorbent. What evidence have we of 
the secretory activity of the cells in the tubules ? 

The great solubility and diffusibility of urea render it impossible to 
trace this substance on its way through the kidney by micro-chemical 
means. <A better prospect of success would seem to be afforded by 
the more insoluble uric acid and urates; and both Bowman! and y. 
Wittich? have described the presence of uric acid crystals in the cells 
of the convoluted tubules of birds. Semicrystalline deposits of guanin 
have been demonstrated with certainty in the cells of the excretory 
organ of molluses, but later researches by Adolph Schmidt * have shown 
that the observations of Bowman and v. Wittich must have been due 
to faulty methods of preparation. Deposited urates were frequently to 
be seen in the urinary tubules of birds, but never in the cells them- 
selves. In order to throw light upon this point, Heidenhain had 
recourse to a method, devised by Chrzonzscezewsky,* ie. the injection of 
sodium sulphindigotate (indigo-carmine) into the blood, and the tracing 
of this coloured substance through the cells of the kidney. 

It is found that this substance is excreted in any quantity by two 
glands only of the body, namely, the liver and the kidney. If 5 cc. of 
a saturated watery solution of the sulphindigotate be injected into the 
veins of a rabbit, within a few minutes the urine becomes a deep blue, 
and on killing the animal the kidneys are found to be stained blue, the 
colour being best marked towards the apex of the pyramid. In order to 
find out in what portion of the secreting substance of the kidney the 
colouring matter is turned out, the flow of urine must be checked, since 
otherwise the excreted pigment is at once washed down into the lower 
parts of the tubules and ureter. To this end Heidenhain® divided the 
spinal cord in the neck. The flow of urine being thus stopped, 5 c.c. of 
the saturated solution of indigo-carmine is injected into the blood vessels ; 
ten minutes later the animal is killed, and the blood vessels of the 
kidney washed out with absolute alcohol. By this means the pigment 
is precipitated in situ. On cutting into the kidney, it is at once seen to 
differ widely in appearance from that of an animal in which the cord 
was intact. Instead of being diffusely stained, the kidney now is coloured 
a deep blue in the cortex, the medulla presenting the normal appearance. 
On examining a section under the microscope, it is seen that the blue 
colour is due to the deposition of pigment granules in the lumen and 


5 
in the striated cells lining the convoluted tubules and the ascending 


1 Loe. cit. 2 Arch. f. mikr. Anat., Bonn, 1875, Bd. xl. S. 81. 
3 Arch. f. d. ges. Physiol., Bonn, 1890, Bd. xlviii. S, 34. 
4 Virchow’s Archiv, 1866, Bd. xxxv. S. 158, > Loc. cit. 


654 THE SECRETION OF URINE. 


limb of Henle’s loop, the capsules and the collecting tubules as well as 
the descending loop of Henle being quite free from pigment. 

A very interesting appearance is offered by the kidney, if, previous 
to the injection, its surface has been cauterised over a small area with 
silver nitrate, the cord being intact. In the cauterised zones, the secre- 
tion of water is stopped, but the excretion of indigo-blue is not affected, 
so that in these zones the blue colour is confined to the cortex, whereas 
in the rest of the kidney the coloration is diffuse. Heidenhain con- 
cludes from these observations that the excretion of mdigo-blue is due 
to the specific secretory activity of the striated cells lining the con- 
voluted tubules and ascending loop of Henle. Since these cells are the 
only cells of the kidney which have the power of excreting indigo- 
carmine, an abnormal constituent of the blood, it is natural to assume 
that they may also possess the specific function of secreting the urea of 
normal urine. 

These conclusions of Heidenhain’s have not, however, passed un- 
challenged. Various observers have pointed out that,in order to obtain 
the results described by Heidenhain, it is necessary to repeat exactly all 
the details of his experiments. If we inject larger doses of the 
sulphindigotate and kill the animal ten minutes after the injection, it 
will be found that, in addition to the staining of the striated cells of the 
convoluted tubules, and the deposition of precipitated pigment in the 
lumen of these tubules, there is also a slight stainmg of Bowman’s 
capsule and the glomerular epithelium. It has been suggested? that 
Heidenhain’s results might be equally well explained on Ludwig’s 
hypothesis, according to which a dilute solution of the dye would be 
exuded into Bowman’s capsules, and would be concentrated by absorption 
of fluid on its way through the convoluted tubules. Indigo-carmine is 
soluble in water and in very weak salt solution, from which it is 
precipitated on concentration. Moreover, indigo-carmine is lable to 
reduction in the living tissues with the formation of a colourless 
product, and these two factors, 7.¢. reduction of the pigment and the ex- 
treme dilution of the glomerular exudation, have been held to explain 
the absence of glomerular staining in Heidenhain’s experiment. By 
increasing the dose injected into the veins and killing the animal soon 
after the injection, these two factors are minimised and a staining of the 
capsules is brought about. Sobieranski? points out that the staining or 
deposition of granules in the cells of the convoluted tubules is confined 
to the parts of these cells bordering on the lumen—a fact which seems 
to indicate that the pigment has been taken up by these cells from the 
lumen rather than from the surrounding lymph spaces. 

These observations are to a certain extent confirmed by the effects of 
the injection of carmine. This substance, which has a much more com- 
plicated composition than sodium sulphindigotate, enjoys the correspond- 
ing advantage of smaller diffusibility, so that it can be more easily traced 
on its way through the tissues of the body. Moreover, it undergoes no 
reduction in contact with the living cells. The circulatory disturbance 
which often accompanies the injection of this substance may be.almost 

1 Pautynski, Virehow’s Archiv, Bd. lxxix. S. 393; Henschen, Akad. Afhandlung f. 
medicinska Graden, Stockholm, 1879 (quoted by Sobieranski) ; v. Sobieranski, Arch. f. 
exper. Path. u. Pharmakol., Leipzig, 1895, Bd. xxxv. S. 144. (The two first papers are 
the subject of a critical paper by Griitzner, Arch. f. d. ges. Physiol., Bonn, 1881, Bd. xxiv. 


S. 441.) 
2 Arch. f. exper. Path. u. Pharmakol,, Leipzig, 1895, Bd. xxxv. 8. 144. 


EXPERIMENTS OF NUSSBAUM. ~ 655 


entirely avoided by using a solution of carmine in very weak soda, and 
carrying out the injection slowly (10 c.c. in five minutes). If we kill 
the animal thirty to forty minutes after the injection, and wash out the 
kidney from the renal artery with absolute alcohol, we find the glomeruli 
stained, the nuclei being red, the glomeruli themselves being of a fainter 
reddish tinge. The epithelium of the convoluted tubules contains fine 
granules of pigment towards the inner part of the cells, and here and 
there deposits of carmine are seen in the straight tubules. Under no 
circumstances are the pigment granules ever found in the basal parts of 
the epithelial cells. There can be no doubt that these appearances 
suggest that the pigment has been taken up by the cells from the lumen 
rather than that it is in the act of excretion by the cells. In neither of 
these two experiments do the facts at our command allow us to come to 
a definite conclusion with regard to their interpretation. In order to 
decide the relative functions of the glomeruli and convoluted tubules, it 
would be necessary to separate in some manner the activities of these 
two parts of the kidney, so as to obtain the action of one or other of 
them in an isolated form. 

Experiments of Nussbaum.—A method for attaining this object 
was devised by Nussbaum,! and promised at first to be of crucial 
importance for the physiology of urinary secretion. The kidneys of 
amphibians possess, as Bowman pointed out, a double vascular supply, 
i.e. trom the renal artery and from the renal portal vein. From the 
former vessel are derived the vasa afferentia to the glomeruli, whereas 
the latter breaks up into capillaries which anastomose round the 
tubules, in conjunction with the capillary ramifications of the efferent 
vessels of the glomeruli. Nussbaum imagined, therefore, that the 
glomerular activities might be altogether excluded by ligature of 
the renal artery. Carrying out a number of experiments of this 
description, he obtained results which seemed to decide absolutely in 
favour of Heidenhain’s hypothesis. Thus, after ligature of the renal 
arteries in frogs, the urimary flow was abolished. <A fiow of urine 
might, however, be evoked by the injection of urea into the blood, 
proving, according to Nussbaum, that the substance was not excreted 
by the glomeruli but by the tubules, and also that the latter struc- 
tures could, under the influence of diuretics, secrete part of the water 
of the urine. In a normal frog the injection of peptone, egg-albumin, 
or sugar into the blood is followed by the excretion of these substances 
in the urine. If, however, the renal arteries be previously tied, none 
of these substances appear in the urime, even when a urinary flow is 
produced by the injection of urea. Carmine also, which is acknow- 
ledged by all observers to be excreted by the glomeruli, does not 
appear in the urine of the frog, if the renal arteries be lgatured. 
Nussbaum concluded, therefore, that the excretory apparatus of the 
kidney consisted of two parts, namely, the glomeruli, which excreted 
water and salts as well as egg-albumin, peptone, and grape-sugar; and 
the tubules, which excrete urea and probably uric acid, together with 
a certain proportion of water. 

These experiments are so definite that they would seem to decide 
the question as to the part played by the various structures of the 
kidney, were it only possible to place reliance on them. This un- 
fortunately is not the case. A careful repetition of Nussbaum’s ex- 

1 Arch, f. d. ges. Physiol., Bonn, 1878, Bd. xvii. S. 580. 


656 THE SECRETION OF URINE. 


periments by Adami, working in Heidenhain’s laboratory, has shown 
that in the frog it is impossible to cut off the blood supply to the 
glomeruli by ligaturing the renal arteries. In fact, after this operation, 
fully half of the glomeruli may be injected from the aorta, owing to 
the free anastomoses between the renal artery and the branches of 
the ovarian arteries and the renal portal vein, and it is difficult to 
understand how Nussbaum can have obtained the very definite results 
described by him. These, therefore, in spite of the ingenuity of the 
methods employed, must be discredited in any discussion concerning the 
functions of the various parts of the kidney tubule. 

Experiments of Ribbert.—A bold attempt to experimentally disso- 
ciate the activities of the two portions of the urmary tubule was made 
by Ribbert,? who adopted the method of excising as far as possible the 
medulla of the kidney, so as to obtain the glomerular secretion after 
it had passed through only the first convoluted tubules. This opera- 
tion is only possible in animals such as the rabbit, in which the renal 
medulla is made up of one Malpighian pyramid. It was carried out 
in the following way:—One kidney having been exposed from the 
back, was cut in two by an incision at right angles to the long diameter 
of the organ, extending into the pelvis. By means of a gouge, as much 
as possible of the pyramid internal to the boundary zone was removed. 
The two halves of the kidney were then placed together and secured 
by sutures, and the other kidney totally excised. Ribbert found that 
such animals during the next twelve to twenty-four hours secreted a 
much larger quantity of urine than they had previously done. The 
urine was more dilute and much lghter in colour than the urine of 
rabbits under normal conditions. No analyses, however, of the fluid 
were made. Ribbert interprets these results as confirming Ludwig's 
hypothesis. But apart from the increased quantity, which does not 
seem to me to be definitely established by Ribbert’s experiments, the 
production of a more dilute urme would be expected on either 
hypothesis, whether we assume with Ludwig that the tubules absorb 
water from the urine, or with Heidenhain that they excrete solid 
substances into the urine. 

Experiments of Bradford.—The very insufficient description of 
his experiments given by Ribbert might incline us to discredit them 
altogether, were it not that somewhat analogous results have been 
obtained by Bradford.* This observer found that extirpation of one 
kidney, combined with excision of a large wedge-shaped piece from the 
other kidney, might bring about one of two results— 

1. If the amount of kidney substance left amounted to one quarter 
of the weight of the two kidneys, the animals (dogs) lived a considerable 
time, but suffered from hydruria, i.e. the quantity of urine excreted was 
largely increased, but the excretion of urea remained unchanged, so 
that the urine was much more dilute than before. 

2. If the amount of kidney left was less than one-sixth of the total 
kidney substance, polyuria was produced, ic. a large increase in the 
excretion of water as well as of urea. This increased production of urea 
was due to a rapid wasting of the proteid constituents, and especially of 
the muscles of the body, so that the animals died in a short time in a 


1 Journ. Physiol., Cambridge and London, 1885, vol, vi, p. 382. 
2 Virchow’s Archiv, 1883, Bd. xciii. S. 169. 
3 Proc. Roy. Soc. London, 1892, vol. li. 


REACTION OF .THE URINE. 657 


state of extreme emaciation. This latter result is difficult to explain, 
and will be discussed in another section of this volume. The former 
result (the hydruria) may, however, be analogous to the results of 
Ribbert’s experiments, and may be due to a diminution in the actively 
absorbing or secretory mechanisms of the kidney, z.e. the convoluted 
tubules. It seems probable that a deficiency in the excretory powers of 
the organism could be more easily compensated by augmenting the 
glomer ular transudation by means of the blood supply to the glomeruli, 
than by increasing the work of the cells of the convoluted tubules. 

Arguments based upon the reaction of urine—An objection which has 
been frequently urged against the filtration hypothesis is that, whereas 
the blood serum or plasma is in all animals alkaline, the urine, except in 
those cases where there is a rich supply of alkali in the food, is acid 
in reaction. It seems difficult to conceive how a process of filtration. 
could effect this change in the reaction of the filtrate. Since all author- 
ities are agreed that the urine undergoes changes in composition on its 
way through the tubules, it becomes important to find out whether the 
urine, as it is formed by the glomeruli, is alkaline or acid. 

Dreser* has sought to determine this question by examining the 
microchemical reactions in the different parts of the kidney in the frog. 
As his indicator he used acid fuchsin (rubin 8.) This substance is a 
brilliant red in acid solutions, but is almost colourless in weak alkaline 
solutions. It is, therefore, a convenient substance to use in order to 
demonstrate the formation of acid in muscle during tetanus. <A strong 
solution of this dye was injected into the dorsal lymph sac of the frog. 
An hour or two later the urme that was secreted was of a deep red 
colour, and was acid in reaction. On examining the kidneys, the dorsal 
part in which the glomeruli are situated was found to be colourless, but 
the tubules in the ventral part were filled with red secretion. If the 
injection were repeated the red coloration extended to the lining cells 
of the tubules. From his experiments with this and other dyes, Dreser 
concludes that the production of the acid reaction is effected by the cells 
of the convoluted tubules, and that the glomerular transudate is alkaline. 

This conclusion is borne out by the results of injecting any kind of 
diuretic. If the glomerular transudate is alkaline, and is also rendered 
acid in its passage through the tubules, we should expect that the more 
abundant the glomerular transudate, the shorter would be the time taken 
in its passage through the tubules, so that the urine pouring into the 
bladder would tend to approximate in reaction and composition the 
original glomerular transudate. Such is found to be the case. Whatever 
means we use to induce profuse diuresis, whether by the injection or 
administration of drugs such as caffein or theobromin, or the adminis- 
tration of saline diuretics, or the production of hydreemic plethora, 
we find that the acid reaction of the urine disappears, to be replaced by 
a neutral or alkaline reaction. We may conclude, with a high degree of 
probability, that the glomerular part of the urinary secretion is alkaline 
in reaction, and that the acid reaction of the urine of carnivora or 
of starving herbivora is due to the changes wrought on the glomerular 
transudate by the cells of the convoluted tubules. Whether this 
change is due to the secretion of acid salts, or to the absorption of 
alkaline salts by the cells of the tubules, we are not in a position to 
determine. 

1 Ztschr. f. Biol., Miinchen, 1885, Bd. xxi. S. 41. 
VOL. 1.—42 


658 THE SECRETION OF ORINE. 


An ingenious attempt has been made by Liebermann! to explain the 
chemical mechanism by which the cells of the tubules effect this change in 
reaction. This author has described a class of bodies which may be extracted 
from the mucous membrane of the stomach or from the kidney, and which 
consist of compounds of lecithin and proteid. These he designates lecith- 
albumins. These substances are acid in nature, and are capable of combining 
with alkalies. Liebermann imagines that, as the alkaline salts of the blood 
plasma pass through the epithelial cells of the kidney, they are split up by these 
acid insoluble lecith- albumins, which combine with a portion of the bases, so 
that the remainder of the fluid which reaches the lumen of the tubule contains 
acid salts or free acid. Of course this process would come to an end as soon as 
the acid affinities of the lecith-albumins in the cells were satisfied, and in this 
way one might explain the speedy appearance of an alkaline reaction when 
large quantities of urine are secreted. Under normal circumstances, however, 
Liebermann assumes that the carbon dioxide, which is the normal product of 
tissue metabolism in the kidney, splits up the compound formed in the cells 
into free lecith-albumin and alkaline carbonates, these latter being then 
removed by the venous blood stream. As supporting evidence for this hypo- 
thesis, Liebermann states that the kidney tissue, like lecith-albumin itself, if 
treated with soda solution, and then washed repeatedly with water to remove 
excess of the latter, becomes strongly alkaline. If now the alkaline tissue be 
suspended in water, through which a stream of CO, is passed, and be then 
again washed thoroughly , it will be found to be strongly acid, having given up 
all its soda to the carbon dioxide. 


Conclusions.—It is evident that the experimental facts at our pre- 
sent disposal do not allow of a definite decision as to the exact manner 
in which the secretion of urine is effected. It will be convenient, 
therefore, to summarise the two modes of interpretation, either of which 
may be applied to the known facts. 

‘According to the Bowman-Heidenhain hypothesis, the secretion of 
urine is due to the activity of two sets of cells. The flattened epithelial 
cells covering the glomeruli take up from the blood, circulating through 
the elomerular capillaries, water and salts, and transfer these substances 
to the beginning of the urinary tubule. Their activity is chiefly depend- 
ent on the activity of the blood flow through the capillaries. But they 
may be also excited to active secretion by the presence of certain of the 
urinary constituents in the blood, such as water and salts, or possibly by 
diuretics, such as caffein. On the other hand, the rodded cells, lining the 
convoluted tubules and the ascending loop of Henle, secrete specific 
urinary constituents, such as urea and uric acid, together with a certain 
amount of water. They also secrete certain abnormal constituents of the 
blood, such as indigo-carmine. Their activity is chiefly determined by 
the amount of urea or uric acid in the blood. 

If, on the other hand, we accept Ludwig’s hypothesis, we must 
introduce into it certain modifications, necessitated by later inquiries, 
and assume that in the secretion of urine, as in so many other of the 
bodily functions, there is a mixture of what we may term physical and 
phy siological processes. It seems probable that in the glomeruli the 
process is largely if not exclusively physical ; that is to say, we have here 
a transudation of the water y and crystalloid constituents (including 
urea) of the blood plasma. The extent and nature of this transudation 
are determined— 

1. By the pressure in the glomerular capillaries. 

1 Arch. f. d. ges. Physiol., Bonn, 1894, Bd. liv. S. 585. 


CONCLUSIONS. 659 
2. By the velocity of flow through the capillaries. 

3. By the permeability of the “capillary wall and the glomerular 
e pithelium. 

This watery transudate is concentrated and altered on its way through 
the tubules, in consequence of the absorption of water, and probably ‘of 
certain of its crystalloid constituents. This absorption must be due to 
the active intervention of the cells, since the osmotic pressure of the 
urine is considerably higher than that of the blood pressure. Diuretics 
may act in two ways. The saline diuretics increase the pressure and 
velocity of the blood in the glomerular capillaries, not only by increasing 
the volume of the cir culating fluid, but also probably by a direct dilator 
action on the afferent vessels of the glomerul. <A similar local dilator 
effect is produced by drugs such as caffein or theobromin; but in these 
cases the drugs probably ‘exert a paralysing influence on the absorbing 
mechanism of the kidney, @.e. the cells of the convoluted tubules, so that 
the glomerular transudate may undergo little change on its way to the 
ureter and bladder. 


One of the strongest arguments in favour of this modified Ludwig hypo- 
thesis is the fact that the more we augment the flow of urine, whether by 
caffein, saline diuretics, or production of hydremic plethora, the more nearly 
does its osmotic pressure, saline constitution, and reaction approximate that of 
the blood plasma. It would seem that in the glomeruli we have an apparatus 
which, like the capillaries of the abdominal viscera but in a still higher degree, 
reacts to changes in the intracapillary pressure, and so serves to regulate 
accurately the amount of fluid circulating in the blood vessels. 


Whether we look upon the cells of the convoluted tubules as secre- 
tory or absorptive in function, we have at present no evidence that the 
cellular covering of the clomeruli acts otherwise than passively in the 
production of the glomer ular part of the secretion. It must be remem- 
bered, however, that under certain eir cumstances, as after ingestion of large 
quantities of fluid, the osmotic pressure of the urine may f fall below that 
of the blood plasma. Dreser+ interprets this as pointing to an activity 
of the glomerular epithelium. I have shown above that it may equally 
well be explained by assuming an absorption of salts by the w ater-logged 
tubule cells, or an active excretion of water by these cells. I may 
mention here that I. Munk and Senator, as a result of researches carried 
out for the most part on the excised kidney, have come to a conclusion 
analogous to that just stated, namely, that in the production of urine we 
have a co-operation of physical and physiological factors. According to 
these authors, water and part of the urinary salts (especially NaCl) 
are transuded through the glomeruli in direct consequence of the blood 
pressure, 7.e. by a process of “filtration, although the rapidity of the blood 
flow is at least of equal importance with its pressure. The specific 
urinary constituents—urea, uric acid, hippuric acid, etc., together with 
another portion of the urinary salts (NaCl, sulphates and phosphates) 
—are secreted by the active intervention of the cells of the tubules, 
especially the convoluted tubules. These substances are secreted in a 
dissolved condition, and must, therefore, take a certain amount of water 
with them. 

The influence of the nervous system on the secretion of urine. 
-—The discovery by Berkeley * of a distribution of nerve-endings to the 

1 Loc. cit. 2 Virchow’s Archiv, 1888, Bd. exiv. S. 1. 3 Loc. cit. 


660 THE SECRETION OF URINE. 


tubules of the kidney suggests that in this organ, as in the salivary 
glands, the secretion of urine may be under the direct control of the 
central nervous system, apart from any influence that this system may 
have on the renal circulation. We have already seen that the urmary 
secretion is extremely susceptible to variations in the pressure and 
velocity of the blood in the renal vessels, and also that these latter are 
under the direct control of the nervous system by means of vaso-dilator 
and vaso-constrictor nerve fibres. 

Various authorities have described experiments which should 
demonstrate the existence of secreto-motor nerves to the kidney. Thus, 
in 1835, Claude Bernard? showed that in some cases, where puncture of 
the medulla was carried out with the view of producing diabetes, the 
result was an increased flow of urine, containing no sugar, @.e. diabetes 
insipidus. These experiments were repeated in much greater detail by 
Eckhard,? who showed that, in the rabbit, poy uria might be caused, not 
only by a puncture of the medulla, but also | oy chemical or mechanical 
stimulation of the neighbouring portion of the superior vermis of the 
cerebellun, especially “it, previously to the operation, the nerves going 
to the liver had been divided. “Moreover, it is a familiar fact to 
clinicians, that injuries to the head, epileptic attacks, and especially 
lesions in the neighbourhood of the medulla, may bring about a condi- 
tion of diabetes insipidus. 

We know already that division of one splanchnic nerve will cause 
an increased secretion of urine in the kidney of the same side, and it is 
natural to imagine that the mechanism of the increased urinary sec- 
tion after the pigire is of the same nature. Eckhard poimted out, how- 
ever, that the course of events is different in the two cases. After division 
of one splanchnic, the flow of urine is almost immediately somewhat 
increased, and this moderate increase lasts a considerable time (three to 
four hours at least). The first result of puncture of the medulla is a 
cessation of the urinary flow. This is followed shortly by an imerease 
much greater than is caused by section of the splanchnic, but only 
lasting one to two hours. Moreover, the effect of the diabetic puncture 
is observable even after section of the splanchnics, as well as of all the 
nerves which may possibly send branches to the kidney. Eckhard con- 
cludes, therefore, that the effect must be due to one of two causes: 
either an increased general blood pressure, in consequence of the 
stimulus caused by the puncture, or the excitation of nerve fibres which 
run in the walls of the renal artery itself. The first explanation must 
be rejected, since direct measurement of the blood pressure does not 
show any definite rise in consequence of the puncture. We must there- 
tore accept the second explanation as the correct one. Eckhard regards 
these nerve fibres as secreto-motor, and believes that the urinary secre- 
tion is under the control of a nerve centre, situated most probably in 
the medulla. He bases this hypothesis on the facts that section of the 
cord below the medulla stops the flow of urine, and that stimulation of 
the cut cord does not bring back the flow, in spite of the rise of blood 
pressure which is induced. We know now, however, that the negative 
result of stimulating the cut cord is due to the constriction of the renal 
vessels, which occurs together with those of other parts of the body, so 


1 “ Tecons de physiol.,”’ 1835, tome i. p. 339. 
2 Beitr. x. Anat. u. Physiol. (Eckhard), Giessen, 1869, Bd. iv. S. 1-32 and 153-193 ; 
1870, Bd. v. S. 147-178 ; 1872, Bd. vi. S. 1-18 and 51-94, 


INFLUENCE OF NERVOUS SYSTEM. 661 


that the increased general blood pressure is powerless to send more 
blood through or to raise the pressure in the renal capillaries. 

The facts can be equally well explained if we assume that these 
hidden nerve fibres are vaso-dilator in function—an assumption which 
would be in accord with the numerous other facts we have learnt with 

regard to the regulation of the urinary flow by the central nervous 
system. We may conclude, therefore, that the existence of secretory 
nerves to the kidney is not proved, the subjection of the renal secretion 
to nervous influences being effected exclusively through the intermedia- 
tion of the vascular nerves. 

As an additional argument against the dependence of renal secretion 
on the nervous system, Heidenhain quotes a number of experiments 
made by Bidder! on frogs, in which the secretion of urine continued 
normally, although in some animals the whole spinal cord, in others the 
whole nervous system, with the exception of the medulla, had been 
destroyed. 

1 Arch. f. Anat. u. Physiol., Leipzig, 1844, S. 376. 


/ 


THE MECHANISM OF THE SECRETION OF MILK. 
By E. A. SCHAFER. 


ContTENTS :—General Considerations, p. 662—Influence of the Nervous System, p. 663 
—Action of Pilocarpine and Atropine, p. 664—Influence of Diet, p. 664— 
Place of Formation of the Organic Constituents, p. 665—Mamnner in which the 
Secreted Materials pass out of the Cells, p. 665—Mechanism of the Discharge 
of Milk, p. 667. 


THE composition of milk has been dealt with in a previous article 
(pp. 125 to 140). Here it may therefore be simply noted, with regard 
to its organic constituents, that these are remarkable in being peculiar 
to the milk, not occurring in any of the other secretions or tissues of the 
body (cf. however, footnote 1, p. 665), nor in foods which have not been 
prepared from milk. The mammary gland-cells, therefore, unquestionably 
form the products of secretion themselves from materials derived 
through the lymph from the blood, and cannot be regarded, except as 
concerns some of the inorganic substances, as acting merely as filtering 
agents for allowing the passage of materials in solution from the blood. 
And even with regard to the inorganic substances,! the proportion of 
these is so different from that in which they occur in the blood and 
lymph, that no filtration hypothesis appears in any way tenable even for 
these. The gland-cells are further peculiar in that they only, as a rule, 
function actively for a certain period after parturition, being at all 
other times entirely inactive, although capable occasionally—it is said 
even in the male—of being excited to activity by stimulation of the 
nipple by a sucking action, such as that performed by an infant. Prior 
to, and during such periods of activity, the whole gland becomes greatly 
enlarged, both by an increase in size of existing alveoli, and also, perhaps, 
by a sprouting out of new alveoli. The cells lining the alveoli become 
enlarged, and probably also multiply, for they are said to show evidence 
of karyokinesis. 

The alveolar cells begin to accumulate within them granules, 
partly of a proteid, partly of a fatty nature (although the latter may 
more fitly be described as globules), and the alveoli get filled, before 
there is any call for the pouring out of the secretion, with a clear fluid 
(coagulating to a finely granular material in pieces of the gland thrown 
into alcohol), which contains a few fatty globules of different sizes, and here 
and there cells filled with granules, staining with osmic acid, and appar- 
ently identical with the colostrum corpuscles which are found in the milk of 


1 Bunge has shown that, with the exception of iron, the inorganic substances of milk 
occur in nearly the same proportion as in the ash of new-born animals (‘‘ Text-Book,”” Woold- 
ridge’s translation, p. 107). 


INFLUENCE OF NERVOUS SYSTEM. 663 


the first two or three days after parturition, and which are sometimes 
even to be detected during full lactation. These colostrum corpuscles are 
seen to be amceboid when examined on the warm stage, and are, there is 
little doubt, leucocytes which have wandered out from the interstitial 
connective tissue of the gland into the lumen of the alveoli. Some have 
regarded them as detached epithelial cells, and look upon their presence 
in the alveoli and in the milk as evidence of the normal occurrence of 
such detachment during active secretion (see p. 666): but it must be 
admitted that they have neither the appearance of epithelial cells, nor 
do the latter tend to exhibit any such amceboid movement as is shown 
by the colostrum corpuscles. These corpuscles, in fact, seem to be 
rather analogous to the salivary corpuscles (see p. 544), and to be 
similarly derived from emigrated leucocytes. 

During the period of lactation the alveoli secrete milk, not only 
whilst the gland is being drawn by the process of sucking or milking, 
but in the intervals of such processes, so that the milk accumulates 
both in the alveoli and in the ducts. The latter are provided with (in 
some animals very considerable) dilatations, which serve as reservoirs 
for the accumulated’ secretion, and it is mainly this accumulated milk 
which is poured out during the milking. No doubt fresh milk becomes 
secreted to take the place of that which is drawn away: and as a con- 
comitant to this fresh secretion, there is a considerable flush of blood to 
the gland. It has been calculated that the udders of a cow could not 
contain all the milk which is sometimes drawn at one milking, so that 
secretion must be proceeding at the same time. Moreover, the later 
drawn portions of milk contain more solids in proportion than those 
first drawn.! Lehmann? injected sulphindigotate of soda solution 
into a vein of a milch goat, and at once had the animal milked. 
No blue appeared in the milk until the udders were almost com- 
pletely drawn, when there was a slight tinge. On milking the animal 
again, after the lapse of an hour or an hour and a half, the milk which 
had collected in the udder was completely blue. 

_ Influence of the nervous system on the secretion of milk.— 
Although it is a matter of common experience that the quantity and 
quality of the milk is in women materially influenced by the condition 
of the nervous system, the results of experiments upon animals have 
‘furnished evidence on this subject which is either entirely negative, or 
at most of a somewhat conflicting nature. Eckhard,? who was the first 
to attempt to obtain such evidence, found no marked difference in the 
milk either in quantity or quality from the udder of a goat, the nerves 
(branches of external spermatic) passing to which had been cut, as 
compared with the milk drawn from the other side, the nerves of which 
were intact. His observations have been repeated by others,* with 
contradictory results, some having obtained an increase of secretion on 
cutting the nerves, others a diminution. But even if an increase is 
obtained, it has not been determined whether this is due to the 
alteration in the vascular supply to the gland rather than to a direct 
effect upon the gland-cells, such as is obtained in the case of the 

1 For references, see Heidenhain, Hermann’s ‘‘ Handbuch,” Bd. iv. 

2 Die landwirthsch. Versucht, 1887, Bd. xxiii. 8. 473. 

3 Beitr. z. Anat. u. Physiol. (Eckhard), Giessen, 1855. 

4 Rohrig, quoted by Heidenhain (Hermann’s ‘‘ Handbuch,” Bd. iv.); de Sinéty, Gaz. 


méd. de Paris, 1879, p. 593; Valentowicz, Centralbl. f. Physiol., Leipzig u. Wien, 1888, 
Bd. ii. S. 71; Mironow, Arch. de sc. biol., St. Pétersbourg, 1895, tome iil. p. 453. 


664 MECHANISM OF THE SECRETION OF MILK. 


(paralytic) secretion of saliva after section of the chorda tympani. 
Likewise, the effects which have been got by stimulating the cut nerves, 
and which have been usually in the direction of diminishing the 
quantity of the secretion, may well be ascribed to vasomotor changes 
rather than to direct nervous influence. All that can be said, 
therefore, on this question is to repeat the statement, that the 
experimental evidence of such an influence is still lacking, however 
probable its existence may be from the everyday experience of changes 
produced in the milk of nursing women, as the result of emotional 
conditions. 

Action of pilocarpine and atropine——The drug which has the most 
marked effect in increasing most of the secretions of the body, namely, 
pilocarpine, is stated to have little or no effect upon the secretion of 
milk! On the other hand, atropine is well known to be constantly 
employed for nursing women, in whom, for one reason or another, it 
is desired to dry up the secretion. Short, however, of stopping the 
secretion altogether, atropine, given in smaller doses, is found, whilst 
diminishing the amount of fluid secreted, to cause the secretion of a 
more concentrated milk.? 

Influence of diet—The quantity and quality of the food is well 
recognised as having an important influence on the quantity and quality 
of the milk. The most abundant and richest milk is yielded when the 
diet is liberal, and, in the case of carnivora (bitch) certainly, but less 
certainly in the case of herbivora (cow), when it includes a larger pro- 
portion than usual of proteid material. And it is not so much the 
albuminous constituents of the milk (casein and lact-albumin) which are 
increased, but especially the proportion of fat.3 This indeed has been 
held to be one of the most cogent arguments in favour of the view 
contended for by Voit, that animal fat is formed mainly from proteids.* 
An increase of fat in the food, without a simultaneous increase of 
proteid, does not cause an increased secretion of fat in the milk.® 
Not only the amount of proteids and fat, but also the amount of sugar, 
is increased as the result of giving proteid-rich food.6 Alcohol, given to 
goats, has also been found to increase the fat of milk.7 


It does not, of course, follow that because an excess of a particular organic 
principle in the food produces an increase of certain constituents of the milk, 
that these constituents are directly produced from such material, for the effect 
may be produced indirectly by the functions of the gland-cells becoming 
modified, according to the nature of the pabulum they are receiving. Looked 


? Hammarbacher (goat), Arch. f. d. ges. Physiol., Bonn, 1884, Bd. xxxiii. S. 228; 
Cornevin (Compt. rend. Soc. de biol., Paris, 1891, p. 628) found that in the cow the amount 
of milk yielded was not influenced by the daily injection of 0°25 grm. pilocarpine. See 
also Mironow, Joc. cit. 

: 2 Hammarbacher, Zoc. cit. 

* The evidence for this is given by Heidenhain (Hermann’s ‘‘ Handbuch,” 1882, Bd. v.), 
where also all the most important references on the influence of diet up to that date will be 
found. The following may also be cited—W. Kirchner, Milchzeitung, 1891, Bd. xx. 
C. Schneider, ‘‘ Einfluss versch. Fiitterung auf d. Zusammensetz. der Milch,” Diss. 
Leipzig, 1893. 

+ See article on ‘‘ Metabolism. 

° Ssubotin, Virchow’s Archiv, 1866, Bd. xxxvi.; Centralbl. f. d. med. Wissensch., Berlin, 
1866, S. 337; Kemmerich, ibid., S. 467; Kuhn, Journ. 7. Landwirthsch., 1876, S. 381; 
Weiske, zbid., 1878, S. 447 ; Cf. also Juretschke, “ Einfluss versch. Oelkuchensorten auf 
dem Fettgehalt der Milch, ” Tiss. , Leipzig, 1893. 

Je De Munk, Arch. f. opeaseriaeh. u. prakt. Thierh., Berlin, 1881, Bd. vii. S. 91. 

7 Stumpf, ‘Deutsches Arch. Sf. klin. Med. , Leipzig, 1882, Bd. xxx. S. 201. 


” 


FORMATION OF THE ORGANIC CONSTITUENTS. 665 


at in this light, certain substances may be said to stimulate the cells of the glands 
to increased activity in all directions, tending to the production of a larger 
quantity of milk rich in all kinds of solid constituents ; whilst other substances 
may be looked upon as stimulating the cells in a special manner, tending 
to the increased production of certain only of the constituents of the milk. 


Place of formation of the organic constituents.—<As already 
noticed, the fact that the chief organic constituents of the milk are 
peculiar to the secretion, and do not occur as such in the blood or 
lymph, may be regarded as sufficient evidence of their being formed in 
the gland itself". The casein is in all probability produced by a mole- 
cular change in the composition of the serum albumin or globulin, 
which is supplied to the cells from the blood or lymph. The fat may 
be formed by the cells of the gland from proteid, or possibly even from 
carbohydrate materials furnished by the blood; or it may be taken up 
directly from fat which has been formed elsewhere, and which is always 
present in a certain small amount in blood and lymph. For while, on 
the one hand, there exists no clear evidence to show that the mammary 
gland can itself manufacture fat, it is extremely probable that, in 
common with most if not all other cells in the body, the cells of this 
gland do possess such a faculty. With regard to the characteristic 
sugar of the secretion, and which, being characteristic, must be pro- 
duced by the gland itself, there is some evidence to show that this is 
formed from dextrose, which is itself manufactured elsewhere than in 
the gland. That this is so would appear from the following experiment 
by Paul Bert.2 Bert removed the mammary glands from goats, 
then allowed them to become pregnant. After parturition, the 
urine, during three days, contained a substance which reduced cupric 
oxide and appeared to be dextrose. This was not present before par- 
turition, nor was it found in normal animals either before or after 
parturition; it was therefore presumably formed in the organism in 
larger amount than usual for the purpose of becoming converted into 
lactose in the mammary gland. 


In view of the fact that lactose is frequently found in the urine in women, 
and in mammals generally, immediately before and after parturition,’ this 
experiment of Bert seems to need repetition, especially since he appears not to 
have isolated or carefully examined the reducing substance which he detected. 
The lactose found in the urine after parturition has generally been supposed 
to be re-absorbed from the secretion which has formed in the alveoli and ducts 
of the mammary glands. 

Thierfelder * has pointed out that both the casein and sugar of milk could 
be derived from the nucleo-proteids or glyco-proteids of the gland-cells by a 
process of splitting. In support of this view, a formation of lactose is said to 
occur on keeping portions of minced fresh mammary gland in normal saline 
solution at the temperature of the body ; the lactose being preceded by a colloid 
carbohydrate, identical, according to Landwehr,’ with his “animal gum.” This, 
however, does not affect the question of the ultimate sources of origin of these 


1 A small quantity of casein is said to occur in the secretion of the sebaceous glands 
(Neumeister, ‘‘ Lehrbuch,” Aufl. ii. S. 496). This is of interest in connection with 
the fact that the mammary glands have been regarded as representing enlarged and 
modified sebaceous glands. 

2 Compt. rend. Acad. d. sc., Paris, 1884, tome xeviii. No. 13. 

* Hofmeister, Ztschr. f. physiol. Chem., Strassburg, 1878, Bd. i. S. 101. 

4 Arch. f. d. ges. Physiol., Bonn, 1883, Bd. xxxii. S. 619. 

5 Ibid., 1887, Bd. xl. S. 21. 


666 MECHANISM OF THE SECRETION OF MILK. 


constituents, which are probably, as already stated, the proteids and carbo- 
hydrates derived from the food. 


As tothe manner in which the secreted materials of the milk 
pass out of the secretory cells.—If we put aside, as resting upon no 
solid basis of fact, the suggestion of Stricker, which was taken up more 
seriously by Rauber,! that the organic materials of the milk are carried 
into the alveoli by emigrated leucocytes, which there break down and set 
free their proteid, fatty, and other constituents, we find ourselves face 
to face with three possible methods by which the secreted materials 
which are formed and accumulate within the gland-cells may pass into 
the lumen of the alveoli. The three methods are as follows :— 

1. The cells may, as in the case of the sebaceous glands, bodily 
break loose, and, becoming detached and disintegrated, set free their 
contents within the alveoli. 

2. A part only of each cell, namely, the free end, may break loose, 
become detached, and disintegrate. 

3. The cells may extrude their secreted materials into the alveoli,much 
as in the case of other secretions, without undergoing any histological 
disintegration. 

Of these three views, the first has found support mainly on the ground 
of the analogy with what happens in the case of the sebaceous glands of the 
skin (with which the mammary glands might be looked upon as ina certain 
sense homologous), in which such a complete disintegration of the whole 
cell occurs, its place being supplied by another cell, which is produced by 
cell-division. Moreover, the colostrum corpuscles have been regarded as 
examples of such detached cells filled with secretion, which have not 
become disintegrated. Those corpuscles, however, as we have seen, are 
rather to be looked upon as of the nature of leucocytes than as epithelial 
cells; nor do we find such evidence of cell multiplication in the mammary 
gland as would be at all sufficient to account for the very large number 
of cells which would have to become detached in order to furnish the 
organic constituents of the secretion. Heidenhain? has calculated that 
the gland-cells would have to be totally renewed five times in the 
course of every twenty-four hours, in order to yield the solids of the 
milk. The second view may be looked upon as, in a sense, a modifica- 
tion of the first one. It was due originally to Langer, and has been 
ably advocated by Partsch and Heidenhain.? According to this 
view, the secretion products which are formed in the gland become 
gradually accumulated within the free ends of the cells, which in the 
meanwhile lengthen out, and in place of being flat or cubical become 
columnar and project into the lumen of the alveolus. The enlarged free 
end is then supposed to burst or to become detached and disintegrated, 
and thus to set free the accumulated products, while the fixed ends of 
the cells (with the nuclei) are supposed to remain, ready to again go 
through a similar process. 

The evidence adduced in favour of this view is chiefly of a histological 
nature. It is the case that in some alveoli of glands in full secretion, 
the cells are occasionally seen projecting somewhat prominently into 
the lumen; and it is certainly the case also that the cells, and perhaps 
especially such prominent parts, contain fatty globules, similar in 


1“ Ueber den Ursprung der Milch,” Leipzig, 1879. 
* Loc. cit. ° Vide Heidenhain, op. cit. 


THE DISCHARGE OF MILK. 667 


appearance to those of the milk. Nevertheless, it must be admitted 
that such appearances, although they may occasionally be seen, are 
decidedly rare. It is so much more common to see, even in the most 
actively secreting glands, the alveolar cells uniformly flattened, or at most 
very slightly projecting,that I should not hesitate to say that the columnar 
appearance, which has been described and figured by Heidenhain, is 
quite exceptional, and is in all probability due to the alveoli in which 
it occurs being collapsed. Every histologist is aware of the extreme 
differences in shape which are produced in epithelial cells by altera- 
tions in the conditions of the surface which they cover. Thus, even 
the extremely flattened epithelial cells which line the blood vessels 
may, when examined in sections of vessels which have been hardened in 
a contracted and collapsed condition, project like columnar epithelium 
cells into the lumen of the vessel. And the differences in height of 
the cells lining the alveoli of the mammary glands may very well be 
similarly produced. This is indeed rendered probable from the observa- 
tion of Heidenhain,! that in different lobules of a gland the cells vary 
in height, but in the same lobule they have the same height; and by 
the additional observation of the same observer, (a) that in a bitch 
which was suckling seven vigorous puppies the cells were very high; 
(6) that in another well-fed milch bitch, which was not sucked for 
forty-eight hours, they were remarkably low; for the alveoli in these 
cases would be flaccid and tense respectively. 

The histological evidence in favour of this view must therefore be 
admitted to be extremely weak, nor, except perhaps in the case of the 
unicellular glands of some invertebrates, and the similar unicellular 
secreting structures which form the mucus-secreting goblet-cells of verte- 
brates, is there any analogous instance of the extrusion of a secretion 
by the breaking down of part of the gland-cells. Moreover, the 
argument which was used by Heidenhain against the first view, that 
it would involve the renewal of the substance of the epithelial cells of 
the mammary gland five times in twenty-four hours, will apply with 
slight modification equally to the second, and adds a further consider- 
able difficulty to its acceptance. 

The third view, on the other hand, has the analogy of nearly all 
the other secretory structures to support it. It involves no necessity 
for assuming such an enormous building up and breaking down of 
protoplasm as is required for the other two; and although we must 
admit that the present state of our knowledge does not permit us 
to understand how and why it is that certain substances are formed 
in these cells, and pass from them into the lumen of the alveolus, the 
same admission must be made for all other secretions. Nor is the fact 
that the fat of the milk is extruded from the cells in an undissolved 
condition any obstacle to the acceptance of the view in question, since 
it is probable that the granules which are found in many other secretory 
cells (e.g. those of the salivary glands), and which are passed into the 
lumen of the alveolus, are extruded as granules, and are first dissolved 
in the secretion outside the cells.” 


pelIOe: Clit. 

2 The microscopical changes in the cells of the mammary gland during secretion have 
been recently made the subject of study by Steinhaus (Arch. f. Physiol., Leipzig, 1892, 
Suppl., S. 54) and Szabo (ibid., 1896, S. 32). The former finds evidence of frequent mitotic 
division of the cell nuclei (without subsequent division of the cells), and of transforma- 


668 MECHANISM OF THE SECRETION OF MILK. 


The discharge of milk.—The discharge of milk from the ducts, 
which is produced by the action of sucking or milking, is partly the 
result of direct mechanical pressure upon the gland, and especially 
upon the milk reservoirs of the larger ducts, partly due to a con- 
traction of the plain muscular tissue which accompanies these ducts, 
and which appears to be set in action by mechanical stimulation 
of the nipple. The plain muscular tissue occurs also in the nipple 
itself in some abundance, and by its contraction causes a kind of 
erection and increased prominence of the nipple. This probably serves 
the purpose of keeping open the mouths of the gland-ducts which open 
upon the rounded apex of the nipple, thus allowing of the free outflow 
of the secretion.t The flow is also in all probability assisted by a vis 
a tergo, derived from the swelling of the whole gland by the reflex 
dilatation of its arterioles, and consequent increase of capillary pressure, 
and of lymph exudation ; and, to a shght degree also, by newly secreted 
milk, which begins to be formed by the gland-cells, in response either 
to this increased supply of blood and lymph, or to reflex secretory 
influences passing directly to the gland-cells.? 
tion of the nuclear substance into fat. The latter could find no mitoses during lacta- 
tion, although he found two or three nuclei in each cell. He also describes the aceumula- 
tion in the cells of albuminous granules which undergo peculiar changes of form, and 
are ultimately extruded into the alveoli and there dissolved, These observations require 
corroboration. 

1 Cf. Hellier ‘‘On Nipple Reflex,” Brit. Med. Journ., London, Nov. 7, 1896. 

* Cf., however, what has been already said on this subject on p. 663. 


SECRETION AND ABSORPTION BY THE SKIN. 


By E. WaymoutH Ren. 


ConTENts :—Chemical Nature of Skin Secretions, p. 669—The Secretion of Sweat, 
. 676—Electro-Motive Phenomena in Skin Glands, p. 681—-Absorption by the 
Skin of Man, p. 685—Of lower Mammals, p. 688—Of the Frog, p. 690. 


SKIN SECRETIONS. 


Comparative.—The ‘secretions of the skin in vertebrates fall readily 
into two main classes—(a) Those in which a watery solution is elabo- 
rated by the gland-cells, and (4) those in which products of metamor- 
phosis or degeneration of the gland-cells themselves form the secretion. 

As types of the former class may be instanced the sweat of 
mammals, and the slime of fish and many amphibians; of the latter, 
the secretion of the various modifications of sebaceous glands in 
mammals; of the uropygial gland of many birds; and the fibre secre- 
tions of the skins of certain fish (Myzine, Anguilla, etc.). 

Such secretions are put to a variety of uses in the vertebrate series. 
Of the first class, the sweat of the mammal is at once an excretion and 
a means of regulating body temperature by evaporation, while the 
shme of the frog or fish is protective in function. Of the second class, 
the greasiness of the sebum of the mammal, or secretion of the tail 
gland of the bird, protects skin, hair, or plumage from imbibition of 
water; the secretion of the Meibomian glands of the eyelids prevents 
overflow of tears; the viscosity of the ear wax interferes with the entrance 
of foreign bodies into the auditory canal; while, in special cases, volatile 
substances of good or evil odour, contained in the secretion, may serve 
the purposes of sexual attraction or protection from enemies. 

In hairy mammals, it is only in certain cases, or on certain parts of the body, 
that sweating is observed. Rabbits, rats, and mice are not known to sweat at 
all, the dog sweats but little, the cat only on the hairless pads of the feet ; 
while on the other hand the horse sweats profusely on all parts. The snouts 
of pigs and oxen contain glands similar to sweat-glands, the secretion of which 
keeps the part moist. 

Instances of glands used for purposes of sexual attraction are—the glands of 
the suborbital pit of many ruminants and some hogs, the cheek gland of the 
elephant, the pectoral glands of certain tropical bats, the flank glands of shrews, 
the sacral gland of the peccary, the groin glands of antelopes, the preputial glands 
of the beaver and musk-deer, the anal glands of the hare, marsupials, armadillos, 
two-toed sloth, otter, hyenas, and civets, and the glands at the base of the tail 
of shrews and the fox. The anal glands of the skunk are used for protection. 

The hoof gland of most bisulcate ungulates, opening in the cleft between 
the two divisions of the hoof, is probably of use in protecting the horny 


670 SECRETION AND-ABSORPTION BY THE SKIN. 


matter from imbibition of water ; in the one-horned rhinoceros a gland opens on 
the posterior aspect of each foot. 

The function of the curious gland at the back of the thigh of male 
monotremes, supplying its secretion “by a long duct to the hollow horny spur on 
the heel (so lke in arrangement to the poison gland and fang of a snake) is 
not known with certainty. 

There are glands in the skin of the male of the kangaroo, Halmaturus 
rugus, Which secrete a red substance adhering to the hair, while the maxillary 
glands of the female dwarf antelope, Cephalolophus pygmcus, secrete a blue 
substance reddened by acid.! 


CHEMICAL NATURE OF SKIN SECRETIONS. 


(a) Watery secretions.—Naturally the composition of the sweat 
of man and mammals has received more attention than that of other 
skin secretions. 

Since the quantity of sweat secreted is dependent upon so many 
conditions, it is of little value to quote the numbers obtained by 
different observers, apart from a statement of the special conditions 
under which the observations took place. 

There are several methods of collecting the sweat of the whole body, 
or of special parts. Evaporation may be hindered by enclosing a part, 
such as the forearm and hand, in a rubber bag, and the sweat collected 
in a bottle tied into the lower end of the bag.? The subject may sit in a 
Pettenkofer and Voit’s respiration chamber (but breathe through tubes 
to the exterior), and the water given off by the skin be calculated from 
the readings of hygrometers in the ingoing and outgoing currents of 
air.8 Or the secretion of the skin may be stimulated by raising the 
temperature of the surrounding air, while the whole body, with the 
exception of the head, is enclosed in a convenient receptacle* By 
the hot-air method, Argutinsky°® collected a quarter of a litre of sweat 
in half an hour, at a temperature raised during the experiment from 
27° to 41° C. Schierbeck,® by the hygrometrie method, calculated that 
in his own case, when clothed and at rest, the air in contact with the 
skin being at the normal temperature within clothing (32° C.), 2 or 3 
litres of sweat were given off im twenty-four hours. No calculations of 
the total secretion of sweat can be made from local estimates, because the 
richness of various districts of the skin in sweat-glands is very different. 

In the body at rest the sweat is evaporated as fast as it is formed, 
and it is only under conditions exciting the glands to increased action, 
that the fluid collects upon the surface. 

In the resting condition of the body the temperature of the 
surrounding air must be raised to about 33° C. before the stimulus to 
increased activ ity of the sweat-glands is oroeedt 

The following table is of interest as indicating that, at the time of 


l Weber, Arch. f. mikr. Anat., Bonn, 1888, Bd. xxxi. S. 499. For further information 
on such elendss oy Owen, *‘ Comparative Anatomy and Physiology of Vertebrata,’’ London, 
1868, vol. . p. 632; Leydig, Ztschr. f. wissensch. Zool., Leipzig, 1850, Bd. ii. 8. 1 (anal 
lands). 

: 2 Anselmino, Wagner’s ‘‘ Handworterbuch d. Physiol.,” art. ‘‘ Haut.” 
3 Schierbeck, Arch. Ff. Physiol., Leipzig, 1893, S. 116. 

4 Favre, Compt. rend. Acad. d. sc., Paris, 1852, tome xxxv. p. 721. 

J Arch. f. d. ges. Physiol., Bonn, 1890, Bd. xlvi. S. 594, § Loc. cit. 

7 Schierbeck, Zoc. cit: 


CHEMICAL NATURE OF SKIN SECRETIONS. 671 


the breaking out of sweat, the excretion of carbon dioxide by the skin 
is also suddenly increased, a fact probably related to the increased 
activity of the gland-cells :— 
Excretion of Water and Carbon Dioxide by the Skin at various Temperatures 
of Surrounding Air. 
(Separate experiments on same individual, naked, in a Pettenkofer and Voit’s chamber).! 


3 bye F 
Water Excretion | Carbon Dioxide | 


Temperature of Water Excretion "| 3 s Carbon Dioxide pees 
4 Ganmnver. (rms. per Hows). Grae a i ~ | (Grms. per Hour). ictal 

29°°8 C 22-2, 532°8 S37 8: 

B0n4.., 27°8 667 °2 “40 9°6 
SH an 71:9 1725°6 i 8°9 
oie 50°3 1207 °2 BD 8°4 
B28 te 73°74 1761°6 *BD 8°4 
Steet ge 82°6 1982°4 87 20°9 
SpeA 106°8 2563°2 1°04 25:0 
51a ee 107°0 2568 °0 9 26 
Boe 55 158°8 3811-2 1°23 29°5 


The sweat of man is a colourless, opalescent liquid of salt taste, 
poorest in solids of all the secretions, though richest in salts in relation 
to organic solids. 

Sweat is acid in reaction, even when collected from the palm of the 
hand, where there is no danger of admixture of sebaceous secretion.? 
This acidity is probably due to volatile fatty acids, which may be 
subsequently driven off, leaving an alkaline reaction at the surface of 
the skin.? In profuse sweating the acidity may give way to neutrality, 
followed later by alkalinity.* 


In 1000 parts. Favre. | Schottin. Funke. 
Water F : ; : 995°573 97740 988-40 
Solids Z - > C 4°427 22°60 11°60 
Epithelium - - = sl sate 4°20 2°49 
Fat. ; : ; 3 013 ay. Se 
Lactates . : : ‘ 317 
Sudorates . : : oe | 1°562 Bex 
Extractives ; j ijt “005 11°30 shi 
Urea . : : : ; 044 ae 119595) 
Sodie chloride . : 4 2°230 3°60 
Potassic chlcride é - "024 te 
Sodie phosphate . : Traces 1°31 
Alkaline sulphates. : ‘O11 “39 
Earthy phosphates. : Traces ee Bee 
Total salts . i ‘ 3 Bee 7°00 4°36 


Nore to Tasie.—The sudorie or hidrotic acid of Favre has not been found by any 
subsequent observers. He gives the empirical formula, C,,H,,H,O,,. Lactic acid also 
has not been found by any other observer.’ 


1 Schierbeck, oc. cit. 

2 Francois-Franck, ‘‘ Dict. encycl. d. sc. méd.,” Paris, 1884, Sér. 3, tome xiii. p. 51, 
Art. ‘‘Sueur.”’ 

3 Tourton, ‘‘ These de Lyon,” 1879, No. 24, Sér. 1. 

4 Favre, Joc. cit.; Triimpy and Luchsinger, Arch. f. d. ges. Physiol., Bonn, 1878, 
Bd. xviii. S. 494. 

> For analysis of sweat of a rheumatic patient, see Harnack, Mortschr. d. Med., Berlin, 1893, 
S. 91; also Hermann, Jahresb. ii. d. Fortschr. d. Anat. uv. Physiol., Leipzig, 1895, Bd. ii. 
S. 226. 


672 SECRETION AND ABSORPTION BY THE SKIN. 


The specific gravity of human sweat is 1003 to 1006. 

The table on p. 671, from es 1 gives the composition of sweat according 
to Favre,? Schottin,* aad Funke : 

Relatively to the chlorides, Ais and phosphates of sweat are less 
abundant than in urine. The following table is from Kast : 5 — 


| 


} 
Chlorides. Phosphates. | Sulphates. 
——s 
Sweat : : 1 | °0015 “009 | 
| Urine iA 1 Pay a3? 397 


ee 


There is no doubt that urea is present in the sweat of man; the 
variations in estimates of the amount by different observers being 
probably caused by differences in the lapse of time between collection 
and estimation, and consequent variations in the amount of trans- 
formation into ammonium carbonate. 

In two lots of sweat collected by the hot-air method, Argutinsky ° 
found that 363 grm. urea was present in 225 c.c. of sweat collected in 
half an hour, and -410 erm. urea in another sample of 330 c.c. collected 
in three-quarters of an hour. 

Of the total nitrogen excreted by the skin in one case, 68°5 per 
cent. was present in urea, and 51°5 per cent. in ammonia; while in the 
other the numbers given are 74:9 per cent. of total nitrogen in urea, and 
25°1 per cent. in ammonia. 

The same observer, by taking severe walking exercise in a special 
suit of clothes, which was extracted at the end of the period of 
work, and the extract analysed by the Kjeldahl method, obtained results 
as follows :— 


Work. Megrms. of Nitrogen 

excreted by the Skin. 
20 to 22 kilometres in seven hours (July) i ; : 704°4 
18 to 20 ‘5 with ascent of 1300 metres (August) . 753°5 
" x 28 1600 metres (October) 219°3 


The nitrogen excreted by the skin may amount to 4°7 per cent. 
of that by the urine, and hence may have to be taken into account in 
some experiments on nitrogenous metabolism. 

In uremic conditions, the excretion of urea by the skin is greatly 
increased, so much so, in some cases, that crystals of urea have been 
found on the skin.? 

According to Capranica,S creatinine to the extent of ‘04 per cent. 
is present in human sweat. The small amounts of fatty acids are made 
up of formic, acetic, butyric, propionic, and caproic acids. Ethereal 
sulphates of phenyl and skatoxyl are present in small amount, the 
proportion of ethereal to inorganic sulphates being, according to Kast,9 


1** Nouveaux elements de physiologie humaine,” Paris, 1888, 3rd edition, tome ii. p. 
190. 

2 Loc. cit. 

8 <<“ Tye Sudore,” Diss., Leipzig, 1851. 

4 Untersuch. z. Naturl. d. Mensch. u. d. Thiere, 1858, Bd. iv. S. 36. 

° Ztschr. f. physiol. Chem., Strassburg, 1887, Bd. xi. 8. 501. § Loc. cit. 

7 Schottin, Zoc. cit. 

8 Arch. ital. de biol., Turin, 1882, tome ii. ® Loe. cit. 


CHEMICAL NATURE OF SKIN SECRETIONS. 673 


1 to 12. Indigo is sometimes developed in sweat,’ though whether from 
indoxyl secreted, or as the result of the growth of chromogenic 
micro-organisms, is not certain. 


The sweat of the horse has been studied by Leclerc ? and Fred Smith.? 
This secretion normally contains proteids, a fact which may partly account for 
the debilitating effects of profuse sweating in horses. 


Percentage Composition of Sweat of Horse (Fred Smith). 


Alkaline, sp. gr. 1020 ; Water, 94°3776; Organic solids, ‘5288; Ash, 
50936. 


Serum albumin ; : : : 1049 
Serum globulin : : : : 3273 
Fat . é : H ; : : 0020 
Chlorine . : , : : : 3300 
Lime ‘ ; ; : : : 0940 
Magnesia . : : ; ‘ ; "2195 
Phosphoric acid : : : ; Trace 
Sulphuric acid t ; ‘ Trace 
Soda ; : : : : 8265 
Potash . ; : : } SUV ACAD 


Both Leclere and Smith found urea in the sweat of the horse. 

The sweat of the hippopotamus contains a reddish-brown pigment not yet 
identified.* 

Buisine® has investigated the constituents of that part of the “sweat” of 
sheep which is soluble in water. He found potash soaps of the fatty acids 
from acetic to capric ; urea and ammonium carbonate ; potash salts of malic, 
glycolic, pyrotartaric, oxalic, succinic, lactic, hippuric, benzoic, and uric acids ; 
phenylsulphate of potassium, and traces of leucine and tyrosine. Malic acid 
was previously only known as a vegetable product. 

Of the watery secretion of the skin of amphibians little is known. The 
reaction of the secretion of the “mucous glands” is alkaline, while that of 
the “granular glands,” ® chiefly found on the dorsal surface of the flanks 
and legs, is acid. According to Leydig,’ acrid substances are secreted in 
addition to mucin, in the case of the tree frog. In the case of the salamander 
and toad, poisonous substances have been separated.§ 

Gratiolet and Cloez ® state that the poisonous substance in the skin glands of 
the toad and salamander is soluble in alcohol and of the nature of an alkaloid. 
Vulpian !° and more recently Phisalixand Bertrand! have investigated this 
substance in the case of the toad. The symptoms of poisoning are—paralysis 


1 Bizio, Sitzwngsb. d. k. Akad. d. Waissensch., Wien, Bd. xxxix. S. 33; Hofmann, 
Wien. med. Wehnschr., 1873, S. 292; Bergmann, St. Petersb. med. Ztschr., 1868, 
Bd. xiv. 8. 28. 

2 Compt. rend. Acad. d. sc., Paris, 1888, tome evii. p. 123. 

3 Journ. Physiol., Cambridge and London, 1890, vol. xi. p. 497. 

+ Weber, ‘‘ Stud. ii. Saugethiere,”’ Jena, 1886, S. 9. 

>Compt. rend. Acad. d. sc., Paris, 1886, tome ciii. p. 66; 1887, tome civ. p. 1292; 
and 1888, tome evi. p. 1426. 

6 Hermann, Arch. f. d. ges. Physiol., Boun, 1878, Bd. xvii. S. 291. 

7 Arch. f. mikr. Anat., Bonn, 1875, Bd. xii. S. 119; and Biol. Centralbl., Erlangen, 
1892, Bd. xii. S. 458. 

8 Zalesky, Hoppe-Seyler’s Med.-chem. Untersuch., Berlin, 1866, Bd. i. S. 85; Casali, 
Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1873, S. 64; Fornara, dbid., 
USA Mga! 4. 

° Compt. rend. Acad. d. sc., Paris, 1852, tome xxxiv. p. 729. 

Compt. rend. Soc. de biol., Paris, 1854, p. 135. 

1 Arch. de physiol. norm. et path., Paris, 1893, Sér. 5, tome v. p. 511. 


VOL. 1.—43 


674 SECRETION AND ABSORPTION BY THE SKIN. 


commencing in the hindlimbs, slowing and final arrest of the heart, and 
constriction of the pupil. Frogs, guinea-pigs, and small birds are killed by 
injection of the alcoholic extract of the collection of glands forming the 
so-called ‘ parotids” of the toad. The poisonous substance is dialysable, 
and is probably an alkaloid. The blood of toads also contains small amounts 
of this substance, and the serum of a toad will kill a frog if introduced into 
the dorsal lymph sae. 

The slime of fish is secreted by goblet cells in the epidermis, but has been 
little investigated from the chemical standpoint, on account of the great 
difficulty in obtaining it in suflicient quantities, and free from foreign 
substances. The slime of Myine glutinosa is most easily obtained, and is 
found to contain a mucin-like body, which, however, does not yield a 
reducing sugar on boiling with dilute acid.! 

The reaction of the skin of the eel and of Myzine is alkaline to litmus, 
but curiously does not affect phenophthaléin. A reducing sugar can be 
obtained from the slime of the eel by boiling with dilute acid.? According 
to Alcock,’ the slime of the Ammocete larva “yields a proteolytic ferment on 
extraction. 


(b) Sebaceous secretions.—Such secretions are formed by prolifera- 
tion and subsequent degeneration of the cells lining the sebaceous 
glands, in which kary okinetic figures are frequent.* 

These glands are present over the whole surface of the body, with the 
exception of the palms of the hands, soles of the feet, dorsal surface of the 
third phalanges, and glans penis. 

Since it is impossible to collect sufficient quantities of the sebum of 
man for analysis, we have to rest content with analyses of the contents 
of sebaceous cysts, the vernix caseosa of the foetus, or the contents of 
dermoid cysts of the ovary. 

Glycerin and cholesterin fats, fatty acids, albumin (casein ?), free 
cholesterin and isocholesterin, with water and salts, are the main con- 
stituents of sebum. 

The following table is taken from Hoppe-Seyler : °— 


| “Distended 7 Vernia Caseosa pe ai Promitit 
| Gl: ae aan Mek of Man. of Man of Horse. 
js bs | 
Water . : ‘ ‘ ayell 317°0 669°8 
Epithelium and albumin sae 617°5 40°0 56°0 
epee ot peck Lh ol! ae Serre 528-0 499°0 
Fatty acids . : : 5 4 12°1 
Alcoholic extract . 3 ; | fe 150°0 74:0 96°9 
Water extract | 33°0 61:0 54:0 
Ash 5 : F : , | 11°8 
| 


1 Journ. Physiol., Cambridge and London, 1893, vol. xv. p. 488. 
; Reid, Phil. Trans., London, 1894, vol. elxxxy. p. 319. 
8 Proc. Phil. Soc., Cambridge, 1891, vol. vii. pt. 5, p. 252. 
4 Bizzozero and Vasale, Med. Chir. Central. , Wien, 1884, S. 77 and 179. 
5 «* Physiol. Chem.,” Berlin, 1881, Th. 4, 8S. 761. 


CHEMICAL NATURE OF SKIN SECRETIONS. 675 


Sotnitschewsky,! in an analysis of a dermoid cyst of the ovary, found 
tripalmitin, tristearin, and triolein; soaps of the acids of these fats and 
of caproic and caprylic acids, albumin, cholesterin, and an alcohol of 
high molecular weight, which, however, was not cetyl alcohol. Tyrosine, 
hypoxanthin, xanthin, sugar, and glycogen were absent. 

The vernix caseosa of man, according to Ruppel? and Liebreich,* con- 
tains cholesterin fats of oleic and palmitic acids, as well as glycerin fats, 
and also free cholesterin and isocholesterin. 

The cerumen of the ear has been investigated by Petrequin,’ and is 
found to contain potash soaps of oleic and stearic acids in the case of man 
and the ox, while in the dog the base is lime, and in the horse magnesia. 

Wool fat, the sebaceous secretion of the sheep’s skin, was proved by 
Hartmann © to contain no glycerin fats, but only those with cholesterin 
as alcohol. Schulze and Urich* confirmed this, and also found free 
cholesterin and isocholesterin. 

These cholesterin fats (so-called “lanoline”) have been specially 
investigated by Liebreich,2 who finds that they are associated with 
keratinised structures, and are not necessarily formed in sebaceous 
glands, but may be formed within epidermic cells. Tortoiseshell, whale- 
bone, horn, quills of poreupine and hedgehog, hoof of horse, and beak of 
crow, all contain these fats. The skin of the two-toed sloth has no sebace- 
ous glands, and yet contains cholesterin fats, while pigeons bereft of 
their uropygial glands still have these substances in their feathers. 

Such fats are pecular, in that they can take up more than their weight 
of water, and also in that they do not become rancid, and offer a 
complete protection against the entrance of micro-organisms. Liebreich 
compares them to the wax of plants, which is an ether of a monohydric 
alcohol with a fatty acid.® 


The secretion of the tail gland of the bird!° has been chemically investi- 
gated by de Jonge." 

The secretion contains cetyl alcohol, the alcohol of spermaceti. No sugar 
or urea is present. Geese deprived of the tail gland and immersed in water are 
found to take up from two to two-and-a-half times as much water in their 
plumage as normal birds.” 

The so-called “ pigeons’ milk,” with which the young birds are fed by both 
parents during the earlier days of life, is practically a sebaceous secretion of 
temporary glands formed in the lateral pouches of the crop in both cock and 


1 Ztschr. f. physiol. Chem., Strassburg, 1880, Bd. iv. S. 345. 

2 Ernst Ludwig (Ztschr. f. physiol. Chem., Strassburg, 1897, Bd. xxiii. S. 38) has quite 
recently found cetyl alcohol in the contents of dermoid cysts of the ovary. 

3 Tbid., 1895, Bd. xxi. S. 122. 

4 Verhandl. d. Berl. physiol. Gesellsch.,” in Arch. f. Physiol., Leipzig, 1890, S. 363. 

> Compt. rend. Acad. d. sc., Paris, 1869, tome lxix. p. 987; also 1869, tome Ixviii. 
p- 940; Jahresb. ti. d. Fortschr. d. Thier-Chem., Wiesbaden, 1871, Bd. i. S. 36; 1874, 
Bd. ii. S. 33. 

§ Inaug. Diss., Gottingen, 1868. 

7 Ber. d. deutsch. chem. Geselisch., Berlin, 1872, Bd. v. S. 1075; 1874, Bd. vii. S. 570. 

8 Berl. klin. Wehnschr., 1885, Bd. xlvii. S. 761 ; Compt. rend. Acad. d. sc., Paris, 1888, 
tome evi. p. 1176; and ‘‘ Verhandl. d. Berl. physiol. Gesellsch.,” in Arch. f. Physiol., 
Leipzig, 1890, S. 363. 

* The secretion of the Harderian gland of the orbit of rodents, though fatty in nature, is 
not formed by disintegration of cells ; Wendt, ‘‘ Ueber die Harder’sche Driise,” Strassburg, 
1877 ; Kamocki, Biol. Centralbl., Erlangen, Bd. ii. S. 709. 

10 For anatomy, see Robby Kossmann, Zschr. f. wissensch. Zool., Leipzig, 1871, Bd. 
xxi. S. 568. 

Ll Zischr. f. physiol. Chem., Strassburg, Bd. iii. S. 225. 

2 Max Joseph, Arch. f. Physiol. Leipzig, 1891, S. 81. 


676 SECRETION AND ABSORPTION BY THE SKIN. 


hen. It contains fat, a proteid clotting with rennet, globulin, salts, and water, 
but is free from sugar.! 

The secretion of the leg glands of lizards is probably of sebaceous nature.” 

In certain fish, in addition to the secretion of slime by the goblet cells of 
the epidermis, a formation of fibrils takes place from specialised cells, termed 
“club cells,” which may be distributed in the general epidermis or located in 
special glandular involutions, as in the Myxinoid fishes. This secretion reaches 
its highest development in the Myxinoids, and accounts for the extraordinarily 
tenacious slime of this class. The process has, however, also been observed in 
the case of the eel and lamprey.* 


MECHANISM OF THE SECRETION OF SWEAT. 


Goltz* in 1875 discovered the fundamental fact that excitation of 
the peripheral end of the divided ‘sciatic causes the appearance of beads 
of sweat on the hairless pads of the hind-foot of the cat. He also saw 
the same effect ina dog. In the next year, Ostroumow,’? and Kendall 
and Luchsinger ® confirmed the result, and extended the details of the 
experiment. 

Ostroumow showed that excitation of the abdominal sympathetic 
cord produced the same effect ; that even after ligature of the aorta, sweat 
was still secreted upon excitation of the appropriate nerves ; and, finally, 
that injection of atropine completely annulled the effect of such excita- 
tion. 

Kendall and Luchsinger obtained the effect upon the fore-leg of the 
cat and dog, by exciting the nerves of the brachial plexus, confirmed 
the fact of the persistence of secretion after occlusion of the aorta, or 
erural artery in the case of the hind-linb, and further showed that, even 
after amputation of the leg, sweat could be produced on the pads of the 
foot for some fifteen to twenty minutes, by stimulation of the sciatic. 

The fact that the production of sweat is an act of true secretion, 
and the existence of sudorific fibres having been demonstrated, the 
course of the fibres from the spinal cord next engaged attention. 

The existence of sweat-fibres for the lower limb in the abdominal 
sympathetic cord, demonstrated by Ostroumow, was confirmed by 
Luchsinger’ and Nawrocki, and extended by both the latter observers ® 
to the thoracic sympathetic cord, for the fore-limb. Later, sudorific 
fibres for the face, running in the cervical sympathetic, were demon- 


1 John Hunter, ‘‘ Observations on Certain Parts of the Animal Hconomy,’’ London, 1786, 
p- 191; Hasse, Ztschr. f. rat. Med., 1865, Reihe 3, Bd. xxiii.; Claude Bernard, ‘‘ Les 
liquides de Vorganisme,” Paris, 1859, tome ii. p. 232; Teichmann, Arch. f. mikr. Anat., 
Bonn, 1889, Bd. xxxiv. S. 225; Charbonnel-Salle et Phisalix, Compt. rend. Acad. d. sc., 
Paris, 1886, tome ciii. p. 286 ; Phisalix, Compt. rend. Soc. de biol., Paris, 1890, Ser. 9, tome 
ii. p. 8368; Reid, Rep. Brit. Ass. Adv. Se., London, 1894, p. 812. 

* Leydig, ‘‘Die in Deutschland lebenden Arten der Saurier,” 1872; Batelli, Arch. f. 
mikr. Anat., Bonn, 1879, Bd. xvii. S. 346. 

3 J. Miller, ‘‘ Untersuch. ii. die Eingeweide der Fische,” Berlin, 1845, S. 11 ; Kolliker, 
Wiirzb. med. Ztschr., 1860, Bd. i. S. 1; F. E. Schulze, Arch. f. mikr. Anat., Bonn, 1867, 
Bd. iii. S. 137 ; Foettinger, Bull. Acad. roy. d. sc. de Belg., Bruxelles, 1876, Sér. 2, tome 
xli. p. 599; Blomfield, Quart. Journ. Mier. Sc., London, 1882, vol. xxii. p. 355; Reid, 
Phil. Trans., London, 1894, vol. clxxxv. p. 319. : 

4 Arch. f. d. ges. Physiol., Bonn, 1875, Bd. xi. S. 71. 

> Ref. in Jahresb. ii. d. Fortschr. d. Anat. wu. Physiol., Leipzig, 1877, Bd. v. 

§ Arch. f. d. ges. Physiol., Bonn, 1876, Bd. xiii. S. 212. 

7 Tbid., Bonn, 1877, Bd. xiv. 8. 369. 

5 Centralbl. f. d. med. Wissensch., Wien, 1878, 8. 2. 

9 Nawrocki, Centralbl. f. d. med. Wissensch., Berlin, 1878, S. 17 ; Luchsinger, iid., 
1878, S. 36. 


THE SECRETION OF SWEAT. 677 


strated by Luchsinger! and Nawrocki,? in the horse and pig by the 
former observer, and in the pig by the latter. Both agreed that the 
fibres reach the sweat-glands of the face by the infra- orbital branch of 
the fifth cranial nerve, the junction being effected by branches from the 
cavernous plexus of the sympathetic. Neither of these investigators 
could satisfy himself of the presence of sweat-fibres in the facial nerve. 

The origin of the sudorifie fibres in the spinal cord has been studied 
by Luchsinger, Nawrocki, Vulpian, Ott,? and more recently by Langley.‘ 

In the case of the hind-limb of the cat, according to Langley, the 
sudorific fibres enter the sympathetic cord by the white rami communi- 
cantes of the last two thoracic and first three or four lumbar nerves, 
become connected with nerve-cells in the sixth and seventh lumbar, and 
first and second sacral ganglia of the sympathetic, and leave by the 
grey rami of these ganglia, to enter the anterior divisions of the corre- 
sponding spinal nerves, and so the sciatic. The first and second lumbar 
spinal nerves seem to supply the greatest number of secretory fibres. 
The grey ramus to the sixth lumbar nerve is found to chiefly supply the 
sweat-glands of the inner part of the foot, that to the second sacral 
nerve the outer part, and, in the main, the successive rami from above 
downward supply strips of the skin of the foot from within outwards, 
though considerable, and, in different individuals, varied overlapping of 
fields is noted. 

In the case of the fore-limb, the same observer finds that the sweat- 
nerves are supplied to the sympathetic chain by the fourth to the ninth 
thoracic spinal nerves, the main outflow of fibres being usually found in 
a nerve near the middle of the series. All these fibres run up in the 
sympathetic cord to the ganglion stellatum, where a connection with nerve- 
cells is effected, and by the grey rami of this ganglion reach the brachial 
plexus, and so the median and ulnar nerves for their final distribution. 

The grey rami to the sixth and seventh cervical nerves seem to chiefly 
supply the inner part of the fore-foot, while that to the first thoracic 
nerve chiefly supplies the outer part. 

The fibres for the face, according to Nawrocki, leave the cord by the 
second, third, and fourth anterior roots, and run up in the cervical sym- 
pathetic to finally reach the infra-orbital branch of the fifth cranial 
nerve, vid the cavernous plexus. 


Vulpian® and Ott’ maintained that, in addition to the sudorific fibres 
supplied to the limbs vii the sympathetic, others are supplied directly from 
the cord with the nerves forming the limb plexuses. The existence of such 
fibres was denied by Nawrocki, and Langley fully confirms the statements of 
this observer. 

Furthermore, Vulpian and Ott maintained that inhibitory fibres to the 
sweat-glands exist, and the theory has been recently revived by Arloing.® 

Vulpian’s evidence for the existence of such fibres was, that contem- 


1 Arch. f. d. ges. Physiol., Bonn, 1880, Bd. xxii. S. 126. 

2 Centralbl. f. d. med. Wissensch., Berlin, 1880, S. 945. 

3 Compt. rend. Acad. d. sc., Paris, 1878, tome Ixxxvi. pp. 1308 and 1434; Ott, Journ. 
Physiol., Cambridge and London, 1879, vol. ii. p- 42. 

4 Thid., 1891, vol. xll. p. 347 ; ibid., 1894, vol. xvii. p. 296. 

5 Eckhard (Arch. f. Anat. , Physiol. Us. wissensch. Med., Berlin, 1849, S. 427) quotes a 
case in man where contusion of the brachial plexus led to continuous sw eating of the hand 
on the side of the injury. 

§ Loe. cit. 7 Loc. cit. 

8 Arch. de physiol. norm. et path., Paris, 1890, Sér. 5, tome ii. p. 1; and 1891, Sér. 5, 
tome ill. p. 241. 


678 SECRETION AND ABSORPTION BY THE SKIN. 


poraneous excitation of cut sciatic and abdominal sympathetic causes less sweat 
on the pads of a ecat’s feet than excitation of sciatic alone, and the sweat- 
stimulating drug pilocarpine causes more sweating when sciatic or sympathetic 
are cut than intact. 

Later, Vulpian! abandoned this theory. He was led to the idea of the 
existence of inhibitory fibres in the cervical sympathetic by consideration of 
the old experiment of Dupuy,” in which section of the cervical sympathetic 
in the horse leads to sweating on the face on the side of section. Mere excess 
of blood supply to sweat-glands, from the vaso-dilation which occurs simul- 
taneously, is probably per se no stimulus to the action,* but there is no doubt 
that the excitability of the glands is thereby raised, and if, with Luchsinger,* 
it is admitted that a few sweat-fibres originate with the fifth cranial nerve, the 
result is simply due to painful reflex, for Luchsinger got no sweating on section 
of the sympathetic in the neck of a chloralised horse, though stimulation of 
the peripheral end gave abundance. 

The evidence adduced by Ott is the immediate cessation of a secretion pre- 
viously evoked by pilocarpine, on excitation of the peripheral end of the 
divided sciatic. Even if it were admissible that the accompanying vasomotor 
constriction could cause the effect (which it is not, seeing that in the ampu- 
tated foot sweat can still be called forth), the result, he maintains, is obtained 
too suddenly to be accounted for in this manner. 

Again, he states that c¢rritation of the abdominal sympathetic causes a 
dryness of the pads of the foot on the side of irritation, and that pilocarpine 
accentuates the difference in condition between the foot on the side of irrita- 
tion and the normal foot on the opposite side. 

Finally, division of the abdominal sympathetic produces moist pads on the 
side of section, and injection of pilocarpine makes these pads sweat before the 
others. 

In Arloing’s experiments on oxen and donkeys, the cervical sympathetic is 
divided, and time is allowed to elapse until the vaso-dilation has passed off. 
Pilocarpine now produces more marked secretion on the side of section, which 
is interpreted as meaning that inhibitory impulses, restraining the action of the 
glands on the sound side, have been removed on the side of section. 

It has always been a matter of difficulty to differentiate the action of two 
oppositely acting sets of fibres running in the same nerve-trunk, and it must 
be admitted that the evidence so far for the existence of inhibitory fibres for 
sweat secretion is not strong. 


Excitation by appropriate stimuli of the regions of the spinal cord 


from which the sweat-fibres emerge leads to an outpouring of sweat on 


the parts of the skin suppled by these fibres. Thus, if the spinal cord 
is divided above the exit of the twelfth thoracic nerve in the cat, and 
the animal exposed to heat (60° to 70° C. for five to ten minutes), sweating 
still occurs on the hind-limbs.® 

Nawrocki® and Marmé?’ denied this effect, and maintained that it 
is only when there is continuity of the cord with the bulb that such 
stimulation causes sweating. Later, however, Nawrocki® obtaimed the 


1 Vulpian et Raymond, Compt. rend. Acad. d. sc., Paris, 1879, tome lxxxix. p. 11; 
Rev. internat. d. sc. biol., Paris, 1880, p. 115; and ‘‘ Lecons sur les substances tox. et 
médic.,” tome i. pp. 148-149. 

2 Journ. de méd., chir., pharm., etc., Paris, 1816, tome xxxvii. 

3 But see Levy, ‘‘ Verhandl. d. Berl. physiol. Gesellsch.,” in Arch. f. Physiol., Leipzig, 
1892, S. 155. 

4+ Tagebl. d. Versamml. deutsch. Naturf. in Baden-Baden, 1879. 

° Luchsinger, doc. cit. 6 Centralbl. f. d. med. Wissensch., Wien, 1878, S. 17. 

7 Nachr. v. d. k. Geselisch. d. Wissensch. u. d. Georg.-Aug. Univ., Gottingen, 1878, 
p. 102. 

8 Centralbl. f. d. med. Wissensch., Berlin, 1878, 8. 721. 


‘THE SECRETION OF SWEAT. 679° 


result in a few cases with divided cord. Obviously a positive case in 
such an experiment is worth many negative, since the excitability of 
the cord below the section may possibly be depressed at the time of 
making the test. It is generally accepted that spinal “sweat-centres ” 
exist. 

On the other hand, no cerebral centres for sweating have yet been 
experimentally demonstrated. 

According to Levy Dorn,? the spinal “sweat-centres” are very re- 
sistant to the action of cold. In cats cooled till the rectal temperature 
was 22° to 28° C., sweating was still obtained by reflex excitation or 
dyspnoea, but heating (70° C.) caused little sweating, the cooled cat 
being as it were “protected,” in that the heat which is to restore it, 
does” not, when applied, immediately call forth a refiex outpouring of 
sweat, by the subsequent evaporation of which, heat would be abstracted 
from the body. 

The nervous mechanism of sweat secretion may be called into action 
by central stimuli, by reflex action, or by peripheral stimuli. A venous 
condition of the blood is one of the most active stimuli to the central 
mechanism, and one frequently employed in experimental work. If an 
animal be partially asphyxiated, after section of the spinal cord in the 
mid-dorsal region, sweat breaks out on the pads of the hind-feet, even 
after division of all the posterior roots behind the section.* 

Raising the temperature of the blood produces a similar effect, and 
the result is also obtained with divided posterior roots, and hence is not 
reflex ; moreover, the effect is stopped by section of the sciatic, and hence 
is not of peripheral origin as a result of heating of the terminal apparatus. 

Certain drugs, especially picrotoxin and strychnia, appear to cause 
sweating exclusively by their action on the spinal cord. Nicotine and 
eserine cause slight sweating after section of the limb nerves, and are 
therefore not exclusively, though mainly, central stimulants.* 

Reflexly, it may be broadly stated that stimulation of almost any 
afferent channel will cause sweating. A cat will sweat on the pads of 
its feet at the sight of a dog, mustard in the mouth causes sweat on the 
foreheads of many persons, and the application of heat to the skin is a 
familiar cause of increased action of the glands. According to Greiden- 
berg,® in a patient with sweating legs, shght skin stimuli diminished the 
secretion, while strong stimuli caused an increase. 

Directly from the periphery, the sweat-glands may be excited by 
certain drugs or by raising their temperature. 

Pilocarpine excites secretion of sweat after complete division of the 
nerves, and localised secretion may be produced by introducing it 
beneath the skin. Its action is probably in the main upon the termina- 
tions of the nerves in the glands, since it is, as a rule, non-effective, when 
sufficient time has been allowed to elapse after section of the nerves to 
ensure complete degeneration (Luchsinger, Nawrocki, and Vulpian). On 
the other hand, Max Levy ® states that pilocarpine may still give good 


1 Bloch, ‘‘ Thése de Paris,” 1880. 

2 “ Verhandl. d. Berl. physiol. Gesellsch.,” in Arch. f. Physiol., Leipzig, 1895, S. 198. 

8 Luchsinger, Arch. f. d. ges. Physiol., Bonn, 1877, Bd. xiv. S. 369. ; Robillard, 
** These de Doct.,” Lille, 1880. 

4Tuchsinger, Arch. f. d. ges. Physiol., Bonn, 1877, Bd. xv. S. 482; Hogyes, ref. in 
Jahresb. ti. d. Fortschr. d. Anat. u. Physiol., Leipzig, 1881, Bd. ix. S. 72. 

> Jahresb. ii. d. Fortschr. d. Anat. u. Physiol., Rue: 1882, Bd. x. S. 81. 

® Centralbl. f. Physiol., Leipzig u, Wien, 1892, Bd. v. S. 68. 


680 SECRETION AND ABSORPTION BY THE SKIN. 


secretion, when excitation of previously divided nerves is without effect, 
pointing to stimulation of the gland protoplasm by the drug. 

According to Rossbach,! small doses act upon the nerve-endings, 
while large doses also affect the gland protoplasm; and some of the 
experiments of Luchsinger, Marme, and Hogyes, in which pilocarpine 
caused secretion, long after the time necessary for complete degeneration 
of the nerves had elapsed, point to the same conclusion. 

There appears to be no central action by pilocarpine, for Robillard? 
after separating the foot of a cat from the body, with the exception of 
the tibial nerve, obtained no secretion of sweat on injection of pilo- 
carpine into the general circulation; though the nerve was proved to 
conduct, by a profuse sweat caused on asphyxiation. 

Muscarine* also acts as a peripheral excitant, but is less active than 
pilocarpine. ‘ 

Atropine and duboisine are both antagonistic to pilocarpine and 
muscarine. 

In the cat an injection into a vein of 3 merms. of atropine is sufficient 
to make stimulation of the sciatic ineffective; subsequent intravenous 
injection of 10 mgrms. of pilocarpine will cause sweating, though the 
nerve is still without action on excitation. In such a case the atropine 
poisons the nerve-ending, but the gland protoplasm is still excitable and 
responds to pilocarpine. According to Rossbach,* a dose of 20 to 30 
megrms. of atropine is needed, in the case of a cat, to paralyse the gland- 
cells to such an extent that subsequent local application of pilocarpine 
is without effect. All glandular apparatus appears to be far more 
sensitive to atropine than to pilocarpine. 

The local paralysing effect of atropine was elegantly demonstrated 
by Aubert.? If the palm or finger (carefully cleaned) is pressed on to 
paper sensitised with silver nitrate, the spots of chloride formed at the 
mouths of the sweat-ducts are quite visible. If the experiment is tried, 
after a pad soaked in atropine solution has been tied over a limited 
surface overnight, that surface is found to yield no spots, in contrast to 
the surrounding field. 

Finally, the terminal sweat apparatus is very sensitive to change of 
temperature. Luchsinger® has shown that not only cold but excessive 
heating retards the action of the glands. Thus if, on a warm day, one 
hand be held in water at 45° to 50° C. for ten minutes, while the other is 
immersed in water at 15° to 30° C., and exercise is then taken, the hand 
which was in water at the lower temperature commences to sweat at 
once, the other not for some considerable time. In experimental work, 
in which the excitation of nerves is undertaken and the outbreak of 
sweat observed, the greatest caution is necessary to keep the tempera- 
ture of the extremities constant, for with a cold foot a nerve root hold- 
ing sweat-fibres in reality, may be wrongly considered to hold none, if 
the terminal apparatus is depressed by cold. 

That the formation of sweat is a true act of secretion, and not 
merely filtration, is shown by experiments already quoted, in which it is 
noted that after stoppage of the circulation sweat is still secreted on 

1 Arch. f. d. ges. Physiol., Bonn, 1880, Bd. xxi. S. 1. 2 Loc. cit. 

* Triimpy and Luchsinger, Arch. f. d. ges. Physiol., Bonn, 1878, Bd. xviii. S. 501; 
Ott and Wood Field, Journ. Physiol., Cambridge and London, 1878, vol. i. p. 193; 
Hogyes, loc. cit. 

ae lipe. Cie. 5 Lyon méd., 1874. 

§ Arch. f. d. ges. Physiol,, Bonn, 1878, Bd. xviii, S. 478, 


ELECTRO-MOTIVE PHENOMENA IN SKIN GLANDS. 681 


excitation of nerves; and further, by the fact that by means of atropine 
the secretion of sweat can be stopped in spite of the continued circula- 
tion of the blood. 

It is probably right to conclude that the blood supply is a necessary 
adjuvant to the prolonged activity of the gland-cells, but not the stimu- 
lant to their action, though, according to Levy, secretion is provoked 
upon reinstallation of the circulation, in a limb with cut sciatic, which 
has been long kept anemic. This effect may possibly be due to the 
mechanical stimulation of the glands by the pulse. 

Levy Dorn? placed the hind-limb of a cat in a receptacle within 
which the air pressure could be raised, and found that the secretion 
could overcome a pressure in excess of that in the large arteries. 

Nothing is definitely known as to the existence or not of any 
action of the nervous system upon the sebaceous glands. 

According to Arloing,? section of the cervical sympathetic in 
donkeys causes exudation of sebum from the sebaceous glands of the 
skin of the ear, reaching its maximum fifteen hours after section, and 
lasting for sixty-four‘hours. Stimulation of the peripheral end of the 
nerve also causes secretion from these glands. 


The glands of the skin of the frog undergo periodic contraction and expan- 
sion by means of their muscular sheaths,* and have been carefully studied by 
Engelmann,® Stricker and Spina,® and Drasch,’ in the web and membrana 
nictitans. The spontaneous movements in the case of the web glands are 
stopped temporarily by section of the sciatic, or seventh, eighth, and ninth 
anterior spinal roots. Excitation of the sciatic or reflex stimulation of the skin 
leads to contraction of the glands, as also does direct excitation by vapours of 
chloroform or ether, or by carbonic acid gas. During contraction of the whole 
gland, by its muscular sheath, the lining gland-cells swell, and, according to 
Drasch, in the case of the membrana nictitans, the fifth cranial nerve, on ex- 
citation, causes contraction of the sheath only, while excitation of the sympa- 
thetic causes swelling of the cells. Pilocarpine causes increased secretion by 
these glands. Stricker and Spina advanced a theory of secretion based upon 
observations of these glands, maintaining that, in the act of swelling, fluid is 
sucked in by the cells from the surrounding lymph spaces, and on contraction 
forced out into the lumen ; the theory obviously involves the assumption of some 
valvular structure in the protoplasm, of which we know nothing, and furthermore 
has been disposed of by Drasch, who has found that the glands of the mem- 
brana nictitans may secrete freely in stages of immobility of the lining cells. 

In the case of fish—in the eel it has been shown that the secretion of the 
goblet cells of the epidermis and of the club cells (when present) is under the 
influence of the nervous system, but the nerve paths have not been worked out.® 


ELECTRO-MOTIVE PHENOMENA IN SKIN GLANDS. 


In attempting to demonstrate the existence of currents in the 
uninjured muscles of the frog, du Bois Reymond ® discovered that the 


1 Loe. cit. 

2 «<Verhandl. d. Berl. physiol. Gesellsch.,” Arch. f. Physiol., Leipzig, 1893, S. 383. 
3 Arch. de physiol. norm. et path., Paris, 1891, Sér. 5, tome iil. p. 241. 

4 Ascherson, Arch. f. Anat. u. Physiol., Leipzig, 1840, S. 15. 

5 Arch. f. d. ges. Physiol., Bonn, 1872, Bd. v. S. 498. 

8 Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1880, Bd. xxx. Abth. 3, S. 95. 

7 Arch. f. Physiol., Leipzig, 1889, S. 96. 

8 Reid, Phil. Trans., London, 1894, vol. clxxxv. p. 319. 

9 <¢Untersuch. ueber thierische Elektricitat,”’ Bd. ii. Abth. 2, S. 9-20. 


682 SECRETION AND ABSORPTION BY THE SKIN. 


skin itself is a seat of electro-motive force, which he located in the 
glands. The current is in the direction from the free to the deep sur- 
face, the former being electrically negative to the latter. A current so 
oriented may be termed “ingoing,” and is the normal direction of the 
“current of rest’ of all secreting membranes, so far investigated. 

The discovery was corroborated by Rosenthal,! and extended to the 
case of the stomach and gut mucose in the frog and rabbit, while 
Hermann? found a similar current in the skins of many fish, and, 
more recently, in the tree frog, proteus, and axolotl? Such currents as 
a rule exhibit spontaneous variations in intensity, especially in the case 
of the skin of the frog. 

Valentin,t and later Roeber,® furthermore found that in the case of 
the frog’s skin excitation of the cutaneous nerves causes a variation in 
the electro-motive force of the resting skin, and the latter observer 
that this phenomenon could be produced by reflex excitation, and 
was not abolished by curare. 

. The direction of the “current of action” evoked by excitation of 
nerves was not found to be constant by Roeber, a fact corroborated by 
all subsequent investigators. Thus Engelmann® observed a double 
excitatory variation of the “current of rest,’ namely, an outgoing 
followed by an ingoing current (negative followed by positive 
variation), while Hermann’ noted an ingoing “current of action,” 
often preceded by an outgoing current of short duration, and Bayliss 
and Bradford® state that it is “scarcely possible to speak of a normal 
excitatory variation.” 

Hermann and Luchsinger® found that the cat’s foot also gave an 
ingoing “current of rest,’ but that the current developed on excitation 
of the sciatic was constantly ingoing, and prevented from development 
by the exhibition of atropine. 

Luchsinger '® demonstrated the existence of exactly similar currents 
in the snout of the pig, goat, cat, and dog on excitation of the cervical 
sympathetic or infra-orbital nerve, and Hermann and Luchsinger ™ in the 
tongue glands of the frog, though in the latter case excitation of the 
hy poglossal or glossophary ngeal nerve gave a triphasic “current of 
action,” an outgoing being interpolated in a long lasting ingoing 
phase. Tarchanoff” has further indicated that parts of the skin of 
man rich in sweat-glands (e.g. palm of hand), are negatively electrical 
to parts poor in sweat- glands (eg. skin over deltoid), and that the 
ingoing “current of action” of such glands can be excited reflexly by 
very slight stimuli, such as sound or even the expectation thereof, 
odours, or mental effort. 

The well-known Willkiirversuch of du Bois Reymond, in which, 
when the index-fingers of the two hands are immersed in vessels of 
liquid in circuit with a galvanometer, a voluntary effort of the 

1 Arch. f. Physiol., Leipzig, 1865, S. 301. 
2 Arch. f. d. ges. Physiol., Bonn, 1882, Bd. xxvii. S. 280. 
3 [bid., 1894, Bd. lviii. S. 242. 
4 Zischr. f. rat. Med., 1861, Bd. ae .S. 208. 
_ Arch. f- Physiol., Leipzig, 1869, S. 633. 
® Arch. f. d. ges. Physiol. Bonn, 1879, Bavi. S. 97 
7 Ibid., 1878, Bd. xvii. S. 291 ; ‘and 1882, Bd. xxii. S. 280. 
8 Journ. Physiol., Cambridge and London, 1886, vol. vii. p. 223. 
9 Arch. f. d. ges. ‘Physiol., Bonn, 1878, Bd. xvii. S. 310. 


10 Tbid., 1880, Bd. xxii. S. 152. 11 Jbid., 1878, Bd. xviii. S. 460. 
i Ibid., 1890, Bd. xlvi. S. 46. 


ELECTRO-MOTIVE PHENOMENA IN SKIN GLANDS. 683 


muscles of one forearm (e.g. grasping a rod) gives a current passing up 
the contracting arm, is probably to be explained by the concomitant 
excitation of the sweat-glands on the side of action. 

Not only in the case of membranes containing complex glands is an 
ingoing “current of rest” observed, but also in secreting membranes 
supplied with unicellular glands (goblet cells), as the phary nx and 
cloaca of the frog,’ or the skin of the fish;? and further more, in certain 
membranes, quite free of secretory structures, and coy ered only by 
stratified epithelium, such as the skin of the pigeon and the mucosa of 
the crop of the same bird in winter.® 

The attempts to explain the causation of the above currents, 1t must 
be confessed, have not been very satisfactory. 

As regards the constantly observed ingoing “current of rest,” 1b is 
obviously “of the first importance to determine whether it is of purely 
epidermic origin, of purely glandular origin, or whether it receives a 
component from both sources. The experiments with the non-glandular 
skin of the bird above-mentioned show that simple stratified epithelium 
can give rise to such a current, and Hermann # has further proved that 
shaving the epidermis of the cat’s foot lowers the electro-motive force of the 
“current of rest.” Furthermore, Bach and Oehler® found that pencilling 
the skin of the frog with solution of corrosive sublimate abolished the 
“current of rest,” though the excitatory change from the glands beneath 
could still be obtained by exciting the nerves of the skin. 

On the other hand, it can hardly be denied that in such cases as 
the gastric mucosa of the frog, where the epithelium is practically all 
converted into unicellular elands (goblet cells), the marked ingoing 

“current of rest” is of olandular origin,® and this must also be the ease 
in such a membrane as the cloacal mucosa of the frog. 

It is simplest, in the present state of knowledge, to admit that both 
stratified epithelium and gland protoplasm can give rise to currents. 

Hermann and Biedermann consider such currents due to alteration 
of metabolic activity in the continuity of protoplasm. Protoplasm 
becoming “altered” to mucus in a eoblet cell is negative electrically to 
the unaltered material at the base of the cell and the same in the 
process of keratinisation in the continuity of epithelium. Since altered 
parts are negative electrically to unaltered or less altered, the result will 
be an ingoing current, whether we choose the glands or the epidermis, 
or both, as the source of the electro-motive force of the “ current of rest.” 

If we turn to the case of the “action current,” it is only in the case 
of the mammalian glands that any clear explanation on the above 
hypothesis is feasible. In these glands, as already mentioned, the 
“current of action” is purely ingoing, and it is only necessary to assume 
that in action the “ difference” between the base and the free border of 
the cells becomes more marked than at rest, with a concomitant develop- 
ment of electro-motive force with ingoing current. 

In the skins and other secreting membranes of amphibians and fish, 
we are met with the difficulty that it is not possible to predict with 
certainty what will be the direction of the “action current” elicited by 


1 Biedermann, zbid., 1893, Bd. liv. S. 209. 

2 Hermann, Joc. cit. ; Reid, Phil. Trans., London, 1893, Bd. clxxxiv. p. 335. 

> Reid, Journ. Physiol., Cambridge and London, 1894, vol. xvi. p. 359. 

4 Arch. f. d. ges. Physiol., Bonn, 1894, Bd. lvili. S. 242. 

> Tbid., 1880, Bd. xxii. S. 30. 6 Bohlen, zbid., 1894, Bd. lvii. S. 97. 


684 SECRETION AND ABSORPTION BY THE SKIN. 


excitation of the nerves. The strength of the stimulus, and the extent to 
which the normal ingoing “current of rest ” is developed, affects the result, 
and hypotheses have been based upon both of these factors of the case. 


Hermann ! long ago suggested the possibility of augmenting and inhibitory 
fibres to the glands, and in his most recent publication? still entertains the 
idea, On the other hand, Biedermann suggests that the two sides of protoplasmic 
activity (the katabolie and anabolic) in the secretory cells are associated with 
generation of electro-motive force, causing currents in opposite directions 
in the two cases; that the electro-motive force of the “current of rest” is 
the algebraic sum of these opposing forces at the moment ; and that the results 
of nerve excitation are related directly to the ascendancy of one or the other 
metabolic action at the time of stimulation. 

The production of an outgoing “current of action” is considered by 
Biedermann as due to the nerve excitation provoking an excess of anabolic action 
in the cell, that of an ingoing “current of action” as due to excess of katabolism, 
so that one and the same class of nerve-fibre is supposed to produce quite 
opposite results in the cell, the effect being partly conditioned by the state of 
the balance in the cell between the two processes at the moment of excitation, 
and partly by the strength of the stimulus. He supposes that the cell process 
least developed at the time of excitation, tends to be stimulated in excess of its 
fellow, so that if the ingoing “current of rest” is weak, as a result of slight 
katabolic ascendancy, excitation tends to cause an ingoing “ current of action ” ; 
and, vice versd, if the ingoing “current of rest” is strong, as a result of marked 
katabolic ascendancy, the result of excitation of the cell is liable to be the 
development of an outgoing “current of action.” 

Hermann objects to this, that if the electrical sign of excess of anabolism 
over katabolism is plus, the induction of such a condition must start from the 
deep ends of the cells, 7.e. from the ends from which they get their pabulum 
from the blood, and excess of positivity of this end of the cell comes, so far as 
the direction of current is concerned, to the same thing as excess of negativity 
at the free end of the cell, associated by hypothesis with katabolic ascendancy, 
and should develop a current in the same direction, ¢.e. ingoing. 

It may also be noted in this connection, that, according to Bohlen,® in 
the gastric mucosa of mammals, cessation of circulation or any interference 
with blood supply tends to convert the normal ingoing into an outgoing 
“current of rest.” If an outgoing current is associated with excess of anabolism 
over katabolism, it is difficult to conceive how withdrawal of blood supply can 
induce such a change. A similar complete reversal of the direction of the 
“current of rest” is obtainable in the secreting membranes of the frog and 
fish by abstraction of heat, or by narcotisation with carbonic acid gas, ether, 
or chloroform. 

A strong stimulus of a nerve trunk may, in practice, cause an outgoing 
action current, and a weak stimulus one that is ingoing, but it is again difficult 
to conceive that difference in the strength of stimulus of one class of nerve- 
fibre can alter the whole character of the metabolism in the cells. 

Hermann was at one time of opinion that the two kinds of glands in the 
frog’s skin might be associated with the two phases of the excitatory variation ; 
and the lip of the eel, which contains no club cells but only goblet cells, gives 
an outgoing “action current,” while the body skin, rich in club cells and poor in 
goblets, gives an ingoing “action current” with the same strength of stimulus ;4 
but since the cloacal or pharyngeal mucosa of the frog, containing only one sort 
of secretory cell, and the non-glandular crop of the winter pigeon, can give 
currents in both directions, the hypothesis is not of universal application. 


1 Arch. f. d. ges. Physiol., Bonn, 1878, Bd. xvii. S. 303. 
2 Tbid., 1894, Bd. lviii. S. 242. 3 Loe. cit. 
* Reid and Tolputt, Journ. Physiol., Cambridge and London, 1894, vol. xvi. p. 203. 


ABSORPTION BY THE SKIN IN MAN. 685 


ABSORPTION BY THE SKIN. 


Man.—To decide the case for or against the possibility of absorption 
by the human skin, would appear a simple problem, yet a literature 
reaching back over a century indicates that the production of un- 
impeachable testimony on either side has proved a matter of no little 
difficulty. 

A fluid in contact with the skin is separated from the blood vessels 
by layers of epidermic cells with intercellular spaces, but since the 
superficial cells (except in the palm of the hand and sole of the foot) 
are greasy with sebum, one of the first conditions for absorption is that 
the fluid shall be able to wet the surface, so that imbibition by the cells, 
or entrance of the fluid into the capillary spaces between them, may 
take place. Though lanoline, the natural fat of the skin, takes up 
water, such action only occurs slowly, and unless the skin is soaked 
long in warm water, it is a familiar observation that it does not easily 
become sodden, except in the case of the palms and soles. It is there- 
fore not to be expected that water or watery solutions will be capable 
of absorption by the skin of man, and the experimental evidence is 
distinctly against such an assumption. 

The method of some of the older observers, of attempting to decide 
the question of absorption of water by immersing a man in a bath after 
weighing, and weighing again after a prolonged sojourn therein, we may 
dismiss by a bald statement of obvious sources of error. 

(a) There is no guarantee that the normal loss of weight of the body 
per unit time, through lungs and skin, is the same during the bath as 
estimated during preceding hours. (The experiments showed, in different 
instances, gains, losses, and absence of change of weight.) ? 

Further, mere soakage of the epidermis of palms and soles may 
mask an actual loss of weight in the bath.’ 

(5) It is impossible to be certain that the epidermis of the whole 
body is devoid of fissures through which water might reach the deeper 
parts. 

(c) It is difficult to totally exclude absorption by immersed mucous 
surfaces. 

(d) A balance sensitive enough to indicate a difference of a few 
grammes on a weight of many kilos., is difficult to construct. 

(e) A considerable loss of surface epidermis occurs in “ drying” the 
body with a towel. 

An improvement upon the method of total immersion is that of 
immersion of a part of the body, but the vessel, instead of being 
weighed before and after immersion of the part of the body, as in the 
experiments of Vierordt and Eichberg,? is better graduated as in the 
experiments of Falck,* or provided with a capillary pipette, by means of 
which absorption can be determined by fall of level of fluid,® because, 
by the gravimetric method, the error from mere soakage of epidermis 
becomes far larger than in the volumetric method, though here also a 
sight diminution in volume accompanies imbibition by the palm or sole, 


1 Jamin et de Laurés, Compt. rend. Acad. d. sc., Paris, 1872, tome Ixxv. p. 60. 

? Poulet, ibid., 1856, tome xlii. p. 435. 

3 Arch. f. physiol. Heilk., Stuttgart, 1856. £ Tbid., 1852. 

® Madden, ‘‘An Experimental Inquiry into the Physiology of Cutaneous Absorption,” 
Edinburgh, 1838 ; Fleischer, Inaug. Diss., Erlangen, 1877. 


686 SECRETION AND ABSORPTION BY THE SKIN. 


if an arm or leg be used, since the combination of a body with water in 
which it is soaked is accompanied by contraction, so that the total 
volume after soakage is less than the sum of the initial volumes. 

Fleischer could obtain no positive evidence of absorption of water 
by the skin of the arm, immersed in a Mosso’s plethysmograph (pro- 
vided with a capillary pipette) for three hours. 

Solutions of chemical substances easily detected in the secretions 
have been much employed, a part of the body being immersed, or the 
solution applied by means of a spray. Colouring matters, inorganic 
salts, and drugs with marked physiological action, have been used. In 
such experiments the chief points to be observed are—(a) Integrity 
of the epidermis before the experiment, and absence of destructive 
chemical action by the substance used during its course; (d) absolute 
exclusion of possibility of absorption by the lungs in the case of a 
volatile substance, or of a salt yielding a volatile substance under the 
action of the sweat; (c) the choice of substances capable of recognition 
with certainty in minute quantities in the secretions. 

Braune,* using foot baths of solutions of potassium iodide, iodine, 
and hydriodic acid, with a layer of oil over the surface of the solution, 
was unable to detect iodine in the secretions. Parisot,? using baths of 
watery solutions of potassium iodide and ferrocyanide, belladonna, digi- 
talis, and the colouring matter of rhubarb, repeated twice a day for 
three to eight days, obtained no evidence of absorption. Hiifner 4 found 
no hthium by the spectroscope in the urine after foot baths of lithium 
chloride. V. Wittich® and Fleischer® were unable to confirm Rohrig’s* 
statement, that aqueous solutions of potassium iodide are absorbed. 
Winternitz® could get no evidence of absorption of 10 to 15 per cent. 
solutions of lithium chloride in water, and results with cocaine were 
negative.® 

Again, Fubini and Pierini?® could get no evidence of absorption of 
the following solutions :—Potassium ferrocyanide, 3 per cent.; santo- 
nate of soda, 2 per cent.: salicylate of soda, 5 per cent.; potassium iodide, 
5 per cent.; and lithium benzoate, 2 per cent., all dissolved in water. 

Hence it is probably correct to conclude that watery solutions not 
acting chemically upon the epidermis, and water itself, are not capable of 
absorption by the intact skin of man. 

If we now turn to the case of fluids that can wet the skin, such as 
chloroform, ether, alcohol, etc., we find that a certain amount of 
evidence of absorption is obtainable in the case of man. 

Since chloroform, though an excellent fat solvent, causes pain and 
blistering when long in contact with the skin of man, the experiments 
have been mostly made with ether and alcohol. Ether is a better 
solvent of fats than alcohol, and hence is more likely to give positive 
results. Krause ** maintained that both alcoholic and ethereal solutions 
of salts are absorbed by the skin, but Fleischer,” using a volumetric 

1 Quincke, Arch. f. d. ges. Physiol., Bonn, 1870, Bd. iii. S. 332. 

 Diss., Leipzig, 1856. 

> Compt. rend. Soc. de biol., Paris, 1863, tome lvii. p. 327. 

+ Ztschr. f. physiol. Chem., Strassburg, 1880, Bd. iv. S. 378. 

° Hermann’s ‘‘ Handbuch,” Leipzig, 1881, Bd. v. Th. 2, 8S. 257. 

§ Loc. cit. 7 “Die Physiologie der Haut,” Berlin, 1876. 

8 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1891, Bd. xxviii. S. 405. 

® See also Soulier, ‘‘ Traité de therapeutique et de pharmacologie,”’ 1891, tome i. p. 385. 


0 Arch. ital. de biol., Turin, 1893, vol. xix. p. 357. 
11 Wagner’s ‘‘ Handworterbuch,”’ 1844, Bd. ii. S. 174. 12 Loc. cit. 


ABSORPTION BY THE SKIN IN MAN. 687 


method, could observe no absorption of absolute alcohol by his own skin 
in an hour and a half, and Ritter* denies entirely the absorption of 
alcohol or alcoholic solutions of salts by the human skin. Winternitz? 
~got spectroscopic evidence of lithium in the urine after keeping the 
skin of the arm in contact with an ethereal solution (with a little added 
alcohol) for three and a half hours, but missed the effect with a purely 
aleohohe solution. The last-mentioned observer also denies the state- 
ment of Parisot,? that solutions of atropine in alcohol and chloroform, 
applied to the forehead, cause mydriasis. 

It would appear that previous removal of the grease of the skin 
by ether allows a slight absorption of watery solutions to take place, 
for Winternitz* got traces of lithium in the urine on applying a watery 
solution of the chloride to the skin cleaned with ether, but not till nine 
hours after the application. 

If a substance applied to the skin is volatile at the temperature 
of the body, the vapour may possibly pass into the capillary spaces 
between the epidermic cells, and dissolve in the fluid in the sweat 
ducts, and so finally reach the blood vessels, and be absorbed; but in 
experiments with such substances the greatest precautions must be 
taken to exclude absorption by the respiratory tract, and again with 
human skin the results of different observers are conflicting. Rohrig’s® 
positive results with tincture of iodine are denied by Fleischer,S who, 
wearing a mask with a tube to the outer air, found no iodine in the 
urine up till six hours after an application to the skin of the back for 
one and a half hours. Next morning Fleischer found iodine in the 
urine, but this may have been absorbed by the lungs during sleep, 
or the result of the destructive action of the substance on the 
epidermis. Mesnil,’ placing the arm in a Mosso’s plethysmograph, filled 
with vapour of iodine, could get no evidence of absorption after thirty- 
two hours’ exposure. On the other hand, guaiacol is asserted by several 
observers to be absorbed.§ 

Oily solutions and unguents, since they “wet” the skin, one would 
expect to be capable of absorption, but such substances are viscous and 
must be mechanically forced into the intercellular spaces and hair 
follicles, if any marked effect is to be obtained. According to Winter- 
nitz,® the mere application of oily solutions of veratrine and aconitine to 
the skin of man is without effect. Baschkis and Obermayer !° obtained 
evidence of presence of lithium in the urine three hours after rubbing 
in an ointment of lthium carbonate, oleic acid, and lanoline, but 
Fleischer 1 could not obtain evidence of absorption of unguents holding 
potassium iodide, veratrine, morphia, quinine, and salicylate of soda, nor 
could Fubimi and Pierini? find salicylic acid in urine after painting a 
solution in oil of almonds on the hand and forearm. 

But the most important case is that of mercurial ointment, which is 
undoubtedly absorbed into the system. In this, in addition to fine 


1 Diss., Erlangen, 1883. 2 Loc. cit. 
5 Compt. rend. Acad. d. sc., Paris, 1863, tome lvii. p. 327. 4 Loc. cit. 
5 Loc. cit. 8 Loc. cit. 


7 Centralbl. f. Physiol., Leipzig u. Wien, 1894, Bd. vii. S. 775. ref. 

8 Sciolla, ‘‘Cronaca della clinica medica di Genova,’ i 1892- 93, p. 191; Linossier and 
Lannois, Compt. rend. Soc. de. biol., Paris, 1894, pp. 108-110 and pp. 214- 215 ; Guinard 
and Stourbe, zbid., 1894, pp. 180-182. 

9 Loc. cit. 0 Centralbl. f. klin. Med., Bonn, Bd. xii. S. 65. 

Eee OCH Cit. 12TH OGMGt: 


688 SECRETION AND ABSORPTION BY THE SKIN. 


globules of mercury, there is present the black oxide of the metal, 
and it is probable that, after formation of calomel by the sodie chloride 
of the sweat, in the presence of oxygen a further conversion into 
corrosive sublimate takes place, which is finally taken up by the blood. 

Though evidence of vaporisation of mercury in mercurial ointment, 
at the body temperature, can be got by hanging a gold leaf over the 
preparation, such vapour cannot of course pass through wet capillary 
walls into the blood. The theory also of a passage of the fine globules 
of mercury through into the blood is denied by Birensprung,? Hoffmann,* 
and Rindfleisch,t though the fine particles are certainly mechanically 
forced into the hair follicles, sweat ducts,>? and the interstices of the 
superficial epidermic cells, thence to gradually undergo removal. 

Finally, mention may be made of the fact that by taking advantage 
of the cataphoric action of the galvanic current (so-called electro- 
osmose),®° it is possible to force watery solutions into the capillary spaces 
between the epidermic cells, and so artificially cause absorption, either 
by subsequent diffusion into the blood vessels, or by the recoil of 
distended spaces forcing fluid into lymphatic channels.’ The direction 
in which the fluid is moved is that of the electrical current, and the 
quantity carried through a porous partition is directly proportional to 
the intensity of the current, but organic membranes are far less 
permeable than porous earthenware.§ 

It is not then to be expected that the effects with human skin 
will be very marked, since, in practice, only a few milliampéres can be 
passed with comfort to the patient. 

Munk? got evidence of iodine and quinine in the urine, with 
positive electrodes of modeller’s clay moistened with potassium iodide, 
and quinine in aqueous solution. Herzog? anesthetised the skin with 
cocaine solution on the positive electrode, when mere application without 
passage of current was without effect, as also was passage of current 
without cocaine. 

Kahn" corroborates this, getting complete anesthesia of the skin in 
twenty-five minutes, by a current of 45 milliamperes, with return of 
sensation in thirty minutes after cessation of current. With a current 
of 1 milliampére, the return of sensation was complete in ten minutes. 
An excised piece of skin which had been anzsthetised by passing 3°25 
milliamperes for thirty minutes through an anode filled with cocaine 
solution tinged with a blue dye stuff, on microscopic examination showed 
the dye stuff only to the depth of the rete Malpighii. 

Lower mammals.—The results of observations upon absorption by 
the skin of lower mammals are here considered apart from those obtained 
from experiments on man, in order to obviate any tendency to treat the 


1 Barensprung, Journ. f. prakt. Chem., Leipzig, 1850, S. 50 ; Voit, Ann. d. Chem., Leipzig, 
1857, Bd. civ. S. 3; Hermann, ‘‘ Lehrbuch d. exper. Toxicologie,” Berlin, 1874, S. 212. 

* Loc. tt. 5 Diss. Wiirzburg, 1854. 

4 Arch. f. Dermat. u. Syph., Wien, Bd. iii. S. 309. 

> Neumann, Wien. med. Wehnschr., 1872. 

6 Porret, Ann. d. Phys. u. Chem., Leipzig, Bd. lxvi. S. 272; du Bois-Reymond, Monatsb. 
Akad. d. Wissensch., Berlin, 1860, S. 846; Wiedemann, dunn. d. Phys. u. Chem., Leipzig, 
1852, S. 321; and ‘‘ Elektricitat,” Braunschweig, 1883, Bd. ii. S. 166. 

7 Pascheles, Arch. f. exper. Path. u. Pharmakol., Leipzig, 1895, Bd. xxxvi. S. 100. 

8 Engelmann, Arch. nee. d. sc. exactes (etc.), 1874, Bd. ix. S. 332. 

9 Reichert, Arch. f. Physiol., Leipzig, 1873, S. 505. 

10 Wiinchen. med. Wehnschr., Bd. xxxiii. S. 222. 

1 Tnaug. Diss., Strassburg, 1891. 


LOWER MAMMALS. 689 


cases as analogous. The skin of the mammals usually employed for such 
experiments is thinner than that of man, less horny, more vascular on 
account of the hair, and in some eases (rabbit) possessed of hair follicles 
with wide mouths. The presence of hair is a source of trouble in experi- 
ment, for, if not shaved, excoriations may be passed over, while, on the 
other hand, the process of shaving is apt to be accompanied by slight 
injuries to the surface. 

As with man, so here there is little positive evidence of absorption of 
watery solutions, and one is inclined to attribute the results of those 
observers who maintain that watery solutions are absorbed, to injuries 
produced in shaving, or clipping, or accidental introduction by mouth or 
lungs. 

Forlanini! maintained that rabbits could be poisoned by painting 
aqueous solutions of strychnia, acidulated with acetic acid, on the skin, 
but v. Wittich? could not get the effect on white rats, nor Fubini and 
Pierini ? with guinea-pigs, while Winternitz * obtained both positive and 
negative results with live rabbits. Fubini and Pierini allowed the tails 
of rats to soak in strychnia and potassium cyanide solutions (for forty 
minutes in the former case and two hours in the latter) without effect. 
Traube-Mengarini® painted the skin of dogs daily for two months 
with aqueous solution of potassium ferrocyanide, killed the animals, and 
treated skin sections with ferric chloride. The blue was only found 
between the surface cells, not reaching deeper than the stratum granu- 
losum. Acidified borax-carmine solution, applied daily for seventy days, 
gave a like result. Fleischer ® got iodine through the belly skin of a 
rabbit (into a watch-glass of water introduced under the skin) in two 
hours from a cylinder full of the tincture, but admits that the structure 
of the skin was altered. 

With ether and chloroform solutions, absorption is more marked 
in the thin skin of the rabbit, guinea-pig, and rat, than in that of man. 

Waller? immersed the leg of a guinea-pig in a mixture of chloroform 
and tincture of aconite, and was able to poison the animal, an effect not 
produced by the tincture alone. White rats with the foot in a chloro- 
form solution of atropine, exhibited a dilated pupil in two or three 
minutes; with the tail (thicker skin) immersed, not till half an hour 
had elapsed. Strychnia in the same way he found was absorbed from 
solutions in chloroform, but not from those in alcohol. 

Winternitz® also found that rabbits absorb strychnia solution in 
chloroform, and points out that this is not merely an effect of “stimu- 
lation,’ because a previous treatment of the skin with mustard or 
ammonia does not hasten the intoxication. 

Winternitz has also pointed out that cleansing the skin of rabbits 
with ether or chloroform allows absorption of aqueous strychnia solution 
to take place, and, microscopically, itis found that silver nitrate solution 
penetrates more deeply if the skin is so treated. Alcoholic washing of 
the skin also tends to make subsequent absorption of aqueous solution 
possible, but to a far slighter degree than in the case of chloroform and 
ether. 


1 Ann. univ. di med. e chir., Milano, 1868, vol. cev. p. 473. 
2 Loe. cit. 3 Loc. cit. AT oer ct. 
5 Arch. f. Physiol., Leipzig, 1892, Supp., S. 1; Arch. ital. de biol., Turin, 1891, 
vol. xvi. p. 159. 
§ Loc. cit. 7 Proc. Roy. Soc. London, 1860, vol. x. p. 122. 8 Loc. cit. 
VOL. I.— 44 


690 SECRETION AND ABSORPTION BY THE SKTN. 


Experiments upon the absorption of oils and unguents by the 
skin of anunals seem to have given conflicting results in the hands 
of different observers. Lassar! anointed rabbits with oil for days in 
succession, and maintains that the organs became loaded with oil. V. 
Sobieranski? asserts the same for vaseline rubbed into the skin of dogs 
and rabbits, and states that tlie substance is found especially in the 
muscles. Fleischer* denies the effect, as also does Winternitz,? though 
the latter observer was able to kill a rabbit by inunction of strychnia 
(2 per cent.) in oil, Adam and Schoumaker® got negative results 
from the inunction of an ointment of strychnia and vaseline into the 
skin of the necks of dogs. Mercury, however, is absorbed by dogs and 
horses from mercurial ointment. Thus Miller ® rubbed mercurial oint- 
ment into clipped dogs and horses, and found mercury in the feces and 
urine. An ointment of corrosive sublimate, sodic chloride, and fat, gave 
mercury in the feces and urine; lead was passed after rubbing in an 
ointment of a lead salt, and application of a potassic iodide ointment 
gave iodine in the saliva. Aqueous solutions of sublimate were without 
effect when applied to the skin of these animals. 

Cataphoric transfer of solutions through the skins of lower mammals 
can be induced more easily than in the case of man. Munk‘ was able to 
poison rabbits with strychnia in aqueous solution, and Kahn® obtained 
the pharmacological effects of physostigmine and strychnia on rabbits, 
and of apomorphine on dogs, by passing a current of 3°5 milliamperes 
through ‘2 per cent. solutions in the positive electrode, and in all cases 
proved that applications of the solutions without concomitant passage 
of current was without effect. 

Frog.—In the case of the frog the conditions for absorption of 
watery solutions by the skin are far more favourable than in that of 
mammals, for the surface is kept constantly moist by the secretion of 
the skin glands, and no greasy matter is present, so that it is a matter 
of common laboratory experience that poisonous solutions applied to 
the skin of the animal rapidly produce their specific effects. 

Blood vessels are abundant in the skin, especially in that of the 
back, and substances must diffuse with ease through or between the 
moist epidermic cells into the underlying vessels. It would, however, 
appear probable that, in addition to simple diffusion, the physiological 
condition of the lower epidermic cells affects the passage of substances 
through the skin. 

Reid® found that the direction of easier osmotic transfer of fluid 
through freshly removed frog’s skin is (provided the fluids used are 
not deleterious) from without inwards, z.c. the reverse of the direction 
of easier filtration through the dead skin; but that, as its vitality 
declines, the skin becomes less and less permeable from without 
inwards, and finally is more permeable in the reverse direction. The 
duration of the first period, during which the skin is more permeable 


1 Virchou’s Archiv, 1879, Bd. Ixxvii. S. 157; ‘‘ Verhandl. d. physiol. Gesellsch.,” in 
Arch. f. Physiol., Leipzig, 1880, S. 563. 

2 Arch. f. exper. Path. u. Pharmakol., Leipzig, Bd. xxxi. 8. 329. 

3 Virchow’s Archiv, Bd. Ixxix. S. 558. 4 Loc. cit. 

> Journ. de pharmacol., Bruxelles, 1891. 

6 Arch. jf. wissensch. u. prakt. Thierh., Berlin, Bd. xvi. S. 309 ; reference in 
Centralbl. f. Physiol., Leipzig u. Wien, 1891, Bd. iv. S. 550. 

OT aos Cae: 8 Loc. cit. 

® Journ. Physiol., Cambridge and London, 1890, vol. xi. p. 132. 


FROG. 691 


from without inwards, is directly associated with the vigour of the 
animals, lasting seventy to eighty hours after death in strong frogs, 
but only twenty-four hours or so in feeble animals at the end of the 
breeding season. 

Again, the magnitude of an ordinary osmotic stream, maintained 
through freshly removed skin by means of solutions, whose injurious 
effect on tissue life is minimal, is capable of variation in the direction of 
increase or decrease, by such conditions as are known to exalt or depress 
the. activity of living matter. If an osmotic current is set up in the 
direction from without inwards through living frog’s skin (the normal 
direction of greater permeability when the skin is fresh), the presence 
of a stimulant (alcohol) increases, while that of a depressant (chloro- 
form) decreases the current; on the other hand, if the osmotic current 
has been set up in the reverse direction, 7.e. from within out, the stimu- 
lant causes diminution, and the depressant augmentation of the amount 
of fluid transferred from the inner to the outer surface of the skin in a 
given period of time. The phenomena failed to manifest themselves 
when dead skin was made the subject of experiment. The same observer ! 
was also able to demonstrate the existence of a current of ‘6 per cent. 
sodium chloride solution from the outer to the inner surface of freshly- 
removed skin, when the same solution at equal pressure was on either 
side, and hence filtration and osmosis put out of court. 

These results are difficult to explain, and must provisionally be 
attributed to some unknown epithelial action. 


1 Brit. Med. Journ., London, 13th Feb. 1892. 


CHEMISTRY OF RESPIRATION. 
By M. 8S. PEMBREY. 


Contents :—Historical, p. 692—Respiratory Changes in Air-Methods, p. 694— 
Conditions affecting Respiratory Exchange. p. 700—Cold-Blooded Animals, p. 
701—Fishes, p. 704—Warm-Blooded Animals, p. 706—Influence of External 
Temperature, p. 709—Of Muscular Activity, p. 714—Of Food, p. 717—Of Size 
of Animal, p. 720—Of Time of Day, p.721—Of Age, p. 722—Respiration by 
Skin in Amphibia, p. 723—In Mammals, p. 725—Effects of Varnishing Skin, 
p. 727 — Respiration in Alimentary Canal, p. 728— Respiration of Feetus, 
p. 730—Of Embryo, p. 733—The Respiration of different Gases, p. 735—The 
Respiration of Vitiated Air, p. 741—Asphyxia, p. 743—Exchange of Gases 
between Blood and Air, p. 745—Frequency of Respiration in Man, p. 747—In 
Animals, p. 753—Changes in Composition of Air, p. 754—Effect of Respiration 
on Blood, p. 756—Gases of Blood- Methods, p. 757—Arterial and Venous Blood, 
p- 760—Condition of Gases in Blood, p. 765—Causes of Gaseous Exchange 
between Blood and Air, p. 773—Exchanges of Gases between Blood and 
Tissues, p. 7830—Causes of such Exchange, p. 783. 


RESPIRATION is essentially the intake of oxygen and the output of 
carbon dioxide by living cells. In the higher animals two phases of 
respiration are distinguished—the eaternal, the exchange of gases between 
the air or water and the blood; and the internal, the exchange between 
the blood, lymph, and the tissues. 


Historical Account.'—The view held by Aristotle (384-322 B.c.), and 
after him even until the fifteenth century, was that respiration drew air into the 
heart and arteries, and so cooled the blood. Malpighi (1621-1694) discovered 
the alveoli of the lungs, and saw the blood flowing through the capillaries of 
the alveoli of a frog’s lung; and Fracassati,? in 1665, noticed that the lower 
layer of a blood clot was much darker in colour than the upper, but that on 
exposure to the air the lower became florid red. Hook * showed the following 
experiment at a meeting of the Royal Society in 1667. The ribs and diaphragm 
of a dog were cut away, and the trachea connected with a pair of bellows. 
The dog fell into convulsions, but revived when air was blown into the lungs. 
Numerous small holes were now made in the surface of the lungs, and by means 
of two bellows the lungs were kept constantly distended with fresh air; the 
dog lay still, and its heart beat regularly. A piece of lung was cut off, and it 
was noticed that the blood circulated even when the lungs were collapsed. 
Hook therefore came to the conclusion that the cause of death was not the 
stoppage of the circulation, but the want of a sufficient supply of fresh air. 
Croon* had previously shown before the same Society a similar experiment ; 


1 For further details see Bostock’s ‘‘ Physiology,” 2nd edition, 1828, vol. ii. p. 61; 
Paul Bert, ‘‘Lecons sur la physiol. comp. de la respiration,” Paris, 1870, p. 1; Zuntz, 
Hermann’s *‘ Handbuch,” Bd. iv. Th. 2, S. 5. 

2 Phil. Trans., London, 1667, p. 492. ° Ibid., 1667, p. 539. 

* Derham’s ‘‘ Physico-Theology,” 4th edition, 1716, p. 146. 


HISTORICAL ACCOUNT. 693 


he strangled a pullet until it showed no signs of life, and then restored it by 
blowing air into its lungs. 

Boyle,! in 1666, showed by numerous experiments with the air-pump that 
a supply of fresh air was essential to life, both animal and vegetable, and he 
was of the opinion “that the depuration of the blood was one of the ordinary 
and principal uses of respiration.” 

Mayow 2 (1668-1674) was the first to discover the real function of respira- 
tion ; he showed that air was a mixture, and that one of its constituents, which 
he named the nitro-aerial gas, was necessary for the support of a flame, that it 
combined with sulphur and other substances with the production of acids, 
that during calcination metals also combined with it and thus increased in 
weight. The nitro-aerial gas (oxygen) was necessary for all forms of life, and 
the respiration of an embryo was analogous to that of the adult. Mayow saw 
the analogy of respiration to combustion, and held that the function of respira- 
tion was to absorb the nitro-aerial gas and to remove the vapours arising from 
the blood. 

Stephen Hales,* about the year 1726, showed that animals in a closed 
vessel absorb air, and that a similar change is effected by a burning candle. 
He also observed, by experiments upon himself, that air is absorbed during 
respiration, and that “noxious vapours” are produced by repeatedly breathing 
air in a bladder; these noxious substances, he found, could be removed by 
potash, and the air rendered fit for breathing. Hales suggested the use of a 
bladder of air and such an absorbent in the foul air of coal mines. He believed 
that during respiration the air cooled the blood and removed aqueous vapour 
and noxious substances, but he rejected the view of Mayow that the blood 
combined with the nitro-aerial gas. 

About the year 1757, Black? discovered that a quantity of “fixed air” 
(carbon dioxide) was given off from the lungs, and that the expired air chiefly 
differed from the inspired by the addition of that gas. He observed that 
animals placed in carbon dioxide gas died of suffocation. 

In 1772, Priestley * published his ‘‘ Observations on Different Kinds of Air,” 
in which he showed that growing plants restored the property of supporting 
animal life to air which had been vitiated by the respiration of animals or by 
the burning of a candle. He also found that carbon dioxide was produced by 
putrefaction and by plants during the night-time. Priestley isolated oxygen 
and nitrogen, and showed that the change of colour in venous blood on 
exposure to the air was due to the action of oxygen, and that blood changed 
colour and gave off “ phlogiston” even when it was separated from the air by 
a moist membrane and by the walls of the blood vessels in the lungs. He 
concluded that respiration deprived the air of a portion of its oxygen and 
imparted to it a quantity of aqueous vapour and “ phlogiston.” 

Lavoisier ® (1777) extended and explained the discoveries of Mayow, Black, 
and Priestley ; he overthrew the old theory of “ phlogiston,” and pointed out a 
distinction between the various so-called phlogistic processes. The calcination 
of metals he showed, as Mayow had observed a hundred years before, to be a 
combination with oxygen, whereby the metals gained in weight; in respira- 
tion, on the other hand, oxygen was not only absorbed, but combined with 
carbon to form carbon dioxide. 

Lavoisier and Laplace showed experimentally that animal heat arose from 
a process of combustion, oxygen combining, as they thought, with carbon in 
the blood ; as regards the seat of this combustion, Lavoisier held that it was 


1 Phil. Trans., London, 1666, p. 424; 1670, pp. 2011, 2035. 

2 Ibid., 1668, p. 833; ‘* Tractatus quinque,” Oxon. 1674. 

3 «*Statical Essays,” 2nd edition, 1731, vol. i. p. 236 e¢ seq. 

4 «*Tectures on Chemistry,” ed. Robison, Edinburgh, 1803. 

5 Phil. Trans., London, 1772, vol. lxii., p. 147. 

6 Hist. Acad. roy. d. sc., Paris, 1775, 1777, 1780, 1789, and 1790. 


694 CHEMISTRY OF RESPIRATION. 


in the lungs, but in earlier works he had admitted that it might be in the 
other organs of the body.! 

It is now known that the essential seat of respiration is in the tissues and 
not in the blood. The demonstration of this fact is chiefly due to the work of 
Pfliiger and his pupils. 


RESPIRATORY CHANGES IN AIR. 


Methods for the measurement of respiratory exchange.—The 
simplest and at the same time the earliest method for the measurement 
of respiratory exchange, is the analysis of the air of a bell jar, before 
and after an animal has been confined in it. Such a method was used 
by Black, Priestley,? Lavoisier and Laplace,* and others. The obvious 
objection to this method is that the products of respiratory exchange 


Fic. 62.—Regnault and Reiset’s respiration apparatus. 


accumulate, while the oxygen diminishes, two conditions either of which 
disturbs the normal respiratory exchange, and in time causes the death 
of the animal.6 Two modifications were introduced by Lavoisier to 
remove these defects: in the one, the carbon dioxide was removed as it 
accumulated, and a fresh supply of oxygen was added; in the other, a 
constant stream of fresh air was passed through the respiration chamber. 
Upon the first of these principles, Regnault and Reiset’ constructed the 
apparatus with which they made numerous and important experiments 
upon respiratory exchange. The above figure shows its construction. 


1 « (Kuvres,’’ 1862, p. 180. 2 ‘* Lectures on Chemistry,” ed. Robison, Edinburgh, 1803. 

3 Phil. Trans., London, 1772, vol. 1xii. pp. 147, 168. 

4 Hist. Acad. roy. d. sc., Paris, 1780, p. 355. ; *‘diuvres de Lavoisier,”’ tome ii. p. 326. 

> Berthollet, Journ. f. Chem. Physik. u. Min., Berlin, 1808, Bd. v. 8S. 388 ; Legallois, 
Journ. f. Chem. u. Phys., Niirnberg, 1817, Bd. xx. S. 118; Valentin, ‘‘ Die Einflusse der 
Vaguslahmung auf die Lungen und Hautausdiinstung,” Frankfurt a/M., 1857 ; Arch. f. 
exper. Path. wu. Pharmakol., Leipzig, 1876, Bd. v. 8S. 143. 

6 Bernard, ‘‘Lecons sur les effets des substances toxiques,’’ 1857, p. 130; Friedlander 
and Herter, Zischr. f. physiol. Chem., Strassburg, Bd. iii, 8S. 19; Stroganow, Arch. f. d. 
ges. Physiol., Bonn, 1876, Bd. xii. 8. 18. See also this article, p. 743. 

7 Ann. de chim. et phys., Paris, 1849, Sér, 38, tome xxvi. 


RESPIRATORY CHANGES IN AIR. 695 


The carbon dioxide is absorbed from the air by caustic potash, and a 
constant supply of oxygen from the reservoirs is driven in, a manometer 
in communication with the animal chamber indicating the pressure. 
Samples of air for analysis can be drawn from the chamber, and thus 
the part played by nitrogen determined, and a control placed upon the 
completeness of the supply of oxygen and the removal of carbon 
dioxide. Modified forms of Regnault. and Reiset’s apparatus have been 
used by Hoppe-Seyler and Stroganow, 1 Pfliiger and Colasanti,? Schulz,* 
Seegen and Nowak.* 

In Scharling’s® respiration apparatus a constant stream of fresh air 
was drawn through the chamber in which the animal was confined. <A big 
barrel served for the chamber, and air freed from carbon dioxide by 
passing through Liebig’s potash bulbs was aspirated through the appar- 
atus ; on leaving the chamber the air passed through a flask containing 
sulphuric acid, which removed the moisture, and through a weighed 
potash bulb of huge size, of which the increase in weight gave the 
amount of carbon dioxide expired by the animal. As a control, a sample 
of air for analysis was removed from the barrel at the beginning and 
end of the experiment. In this method the carbon dioxide alone was 
determined, and the results were inaccurate, for the absorption was 
incomplete, as is shown by the fact that the air leaving the bulbs 
rendered lime water turbid. Many other forms of apparatus constructed 
upon similar principles have been used.® 

With the methods formerly in use it was impossible to maintain a 
steady ventilation, and at the same time completely absorb the carbon 
dioxide. To overcome this difficulty, Pettenkofer’ introduced the 
following modification. The total amount of air drawn through the 
apparatus is measured by a meter; continuous samples of the air 
entering and leaving the chamber are steadily drawn through two 
separate systems of absorption tubes and meters for the determination 
of the moisture, carbon dioxide, and volume of the samples. The 
difference in the amounts of water and carbon dioxide contained in the 
two samples, multiplied by the total ventilation, gives the quantity of 
moisture and carbon dioxide discharged by the animal. The intake 
of oxygen is estimated in the following way. The animal is weighed at 
the beginning and at the end of the experiment, and the difference 
between the weights of carbon dioxide and water discharged, and the loss 
in weight of the animal, represents the oxygen absorbed. Thus if W 
represents the initial weight of the animal, and W, its final weight, then 
W — W,=yw, the loss in weight of the animal. Let CO,+ H,O represent 
the weights of carbon dioxide and water discharged during the experi- 
ment, then CO, + H,O — w=0O,, the oxygen absorbed. In thus estimat- 
ing the oxygen, it is assumed that, apart from the carbon dioxide and 


1 Arch. f. d. ges. Physiol., Bonn, 1876, Bd. xii. S. 18. 

2 Thid., 1877, Bd. xiv. S. 92. 

3 Thid., Bd. xiv. S. 78. 

+ Tbid., 1879, Bd. xix. S. 347. 

5 Ann. d. Chem. u. Pharm., 1843, Bd. xlv. S. 214. 

6 Allen and Pepys, Phil. Trans., London, 1809, pt. 2, p. 412; Dulong, Ann. de chim. 
et phys., Paris, 1841, Sér. 3, tome i. p. 440 ; Despretz, “ibid. 1824, tome XXxvi. p. 337 ; 
Boussingault, ibid., 1844, Ser. 3, tome xi. p. 433 ; Journ. f. prakt. Chem., Leipzig, 1845, 
Bd. xxxy. 8. 402; Senator, Areh. f. Anat. , Physiol. u. wissensch. Med., 1872, S..1; Lieber- 
meister, Deutsches Arch. f. klin. Med. , Leipzig, 1870, Bd. vii. S. 75. 

7 Sitzungsb. d. k.-bayer. Akad. d. Wissensch. 2u Miinchen, math.-phys. Cl., 1862, Bd. 
ix. (2), S. 232 ; Ann. d. Chem. u. Pharm., 1862-63, Supp. Bd. ii. S. 17. 


696 CHEMISTRY OF RESPIRATION. 


water, no weighable amount of nitrogen, or of any other gaseous 
substance, is discharged or absorbed by the animal. 

The figure below represents the modification of Pettenkofer’s 
apparatus, which was introduced by Voit for experiments on animals. 

The absorption of water is effected by flasks filled with pieces of 
pumice saturated with sulphuric acid, and the carbon dioxide is in turn 
absorbed by making the air bubble through a long tube filled with a 
titrated solution of baryta.t 

The advantages of Pettenkofer’s method over those previously in use 
are these—It is possible, owing to the system of ventilation, to make 
experiments upon man; observations can for a similar reason be much 
more prolonged without any danger of disturbance to the normal 
respiratory exchange arising from an accumulation of carbon dioxide ; 
the absorption of the carbon dioxide is more exact. Notwithstanding 
these improvements, Pettenkofer’s method possesses several disadvan- 
tages and sources of error. The apparatus is complicated and costly, the 


Fic. 63.—Voit’s respiration apparatus. 


determination of the moisture is hable to be exact, owing to deposition 
on the walls of the chamber; during the process of weighing the animal 
there is an intake of oxygen, and an output of carbon dioxide and water, 
which are not determined, and can only be calculated approximately ; 
the absorption and estimation of carbon dioxide by the titration of the 
baryta solution has been shown by Haldane and Pembrey? to be less 
exact than it was thought to be. The result of these errors falls upon 
the estimation of the intake of oxygen, for smce O,=CO,+ H,O — w, it 
is evident that the amount of oxygen may be often imexact. This has 
been pointed out and proved by C. and E. Voit and Forster.’ 

It has already been mentioned that Voit+ has constructed, upon 
Pettenkofer’s principle, a smaller apparatus for the determination of 


1 Baryta was first used by Pettenkofer for this purpose, but Dalton had previously used 
titrated lime water. 

* London, Edinburgh, and Dublin Phil. Mag., London, April 1890. 

3 Zischr. f. Biol., Miinchen, 1875, Bd. xi. S. 126.° © -4 Zbid., 1878, Bd. xiv. S. 57. 


~—— 


RESPIRATORY CHANGES IN AIR. 697 


the respiratory exchange in animals. It has the advantages and most 
of the disadvantages above mentioned. The human respiration apparatus 
in the physiological laboratory, Oxford, has been constructed on the 


2 PUMICE & 
%) Hz 504 


Pumice & Sopa LIME 
H2 S04 


Fic. 64.—Diagram of the human respiration apparatus in the Physiological Laboratory 
Oxford.—A. To Aspirator. 


-principle of Pettenkofer’s apparatus, but has been made more exact and 


simple by the use of Haldane and Pembrey’s method of determining 
carbon dioxide and moisture. 
A more exact method is that introduced by Haldane.t It is a 


Fic. 65.—Haldane’s respiration apparatus.—1 and 4, soda lime; 2, 3, and 5, pumice 


soaked in sulphuric acid; Ch, chamber for animal; M, gasmeter : J, water mawo- 
meter ; P, aspirator. 
modification of the apparatus used by Scharling and Pettenkofer, but 
the chief sources of error have been eliminated or greatly diminished, 
and the method has been made extremely simple. The construction is 
shown in Fig. 65 :— 


1 Journ. Physiol., Cambridge and London, 1892, vol. xiii. p. 419. 


698 CHEMISTRY OF RESPIRATION. 


The moisture is absorbed by pumice saturated with sulphuric acid, 
and the carbon dioxide is removed by soda lime, which has been proved 
to be such a rapid and excellent absorbent that the total output of 
carbon dioxide can be determined directly. The animal is weighed in 
the closed chamber before and after the experiment, and thus there is 
no need to calculate the respiratory exchange during that process, and 
no error arises from the deposition of moisture. The air entering the 
chamber is freed from carbon dioxide and moisture, and therefore all 
the moisture and carbon dioxide in the air leaving the chamber come 

from the animal. The 

e intake of oxygen is 

= determined indirectly ; 

(a the animal gives off 

& only carbon dioxide 

A and water, it absorbs 

only oxygen, and the 

amount absorbed — is 

found by subtracting 

the loss in weight of the 

chamber and animal 

from the total loss of 

carbon dioxide and 
water. 

Haldane’s method 
has also been adopted 
for the determina- 
tion of the respira- 
tory exchange of small 
animals and of chick 
embryos.” 

Another method, 
which has been used 
for the observation of 
Fic, 66.—Lowy’s respiration apparatus. the respiratory ex- 

change in man, is the 
determination of the volume of air respired during a limited period, 
and then, from analysis of samples of the inspired and expired air, 
estimating the intake of oxygen and the output of carbon dioxide 
and water. The more recent and exact forms of apparatus con- 


clam | 


Q 


aS 
ite ag oe ie) 


! Haldane and Pembrey, Joc. cit. 

*Pembrey, Journ. Physiol., Cambridge and London, 1894, vol. xv. p. 401; 1894-95, 
vol. xvii. p. 331. 

* Davy, ‘‘ Researches,” p. 431; Ann. d. Phys. u. Chem., Leipzig, Bd. xix. S. 298; Allen 
and Pepys, Phil. Trans., London, 1808, p. 250; 1809, p. 404; Prout, Ann. Phil., London, 
1813, vol. ii. p. 330; vol. iv. p. 331; Journ. f. Chem. u. Phys., Niirnberg, 1814, Bd. xv. ; 
MacGregor, Ann. de chim. et phys., Paris, 1841, Sér. 3. tome ii. p. 538 ; Wertheim, Deutsches 
Arch. f. klin. Med., Leipzig, Bd. xv. ; Wien. med. Wehnschr., 1878 ; Vicrordt, ‘‘ Physiol. 
d. Athmens,” Karlsruhe, 1845; E. Smith, Phil. Trans., London, 1859, vol. exlix. p. 682 ; 
Speck, ‘‘Untersuch. ueber Sauerstoffverbrauch u. Kohlensiureausathmung d. Menschen,” 
Cassel, 1871; Arch. f. exper. Path. wu. Pharmakol., Leipzig, Bd. ii. S. 405; Bd. xii. 
S. 1; Lossen, Zéschr. f. Biol., Miinchen, 1866, Bd. ii. S. 244; Berg, Deutsches 
Arch. f. klin. Med., Leipzig, 1869, Bd. vi. S. 291; Leyden, ibid., Bd. vii. S. 536; 
Andral and Gavarret, ‘Recherches sur l’acide carbonique exhalé,” Paris, 1843 ; 
Marcet, Phil. Trans., London, 1890, B.; Proc. Roy. Soc. London, 1891, vol. xlix. 
p. 103; Jolyet, Bergonié, and Sigalas, Compt. rend. Acad. d. sc., Paris, 1887, tome ev. 
p- 380. 


RESPIRATORY EXCHANGE IN WATER. 699 


structed upon these principles are those used by Zuntz,! Geppert? and 
Lowy.’ A diagram of such an apparatus is shown in Fig. 66. 

The disadvantage of these methods is that, owing to the attention 
of the subject being directed to the breathing, the volume of air 
respired during a limited period is not a fair sample upon which to 
base an exact calculation, and, moreover, the depth and the rate of 
breathing are also liable to another source of disturbance, the resistance 
of the apparatus. For these and other reasons,* the results obtained 
during short periods of observation are liable to lead to erroneous 
conclusions. 

Methods similar to those just mentioned have been employed in the 
case of animals,® the mouth and nose being covered with a respiration 
mask or the trachea connected by a cannula with the apparatus 
necessary for the measurement of the inspired and expired air. It is 
obvious that these methods introduce many sources of disturbance: the 
animals, unless horses be used, must be tied down, and in many cases 
ansthetised, conditions which markedly affect the respiratory exchange.® 
For these reasons the methods of Pettenkofer and Haldane are in most 
cases to be preferred, for the animals are placed under conditions as 
far as possible normal; these methods are, however, unsuitable when 
operative procedures have to be carried on at the same time as the 
determination of the respiratory exchange. 


Methods for the measurement of respiratory exchange in water.— 
The respiration of fishes was studied by Humboldt and Provencal * in the follow- 
ing manner :—The fishes were placed in a flask of water, the gaseous contents 
of which had been analysed, and then after an interval a sample of the water 
was examined and the alteration in its gases determined. The quantity of 
water present was measured, and thus it was possible to estimate the amount 
of gases absorbed and discharged by the fish. A similar method has been 
used by Vernon® for the measurement of the respiratory exchange in marine 
invertebrates. 

Baumert ° improved this method by passing a stream of water through the 
flask containing the animals; the gases contained in a sample of the water 
entering and in the water leaving the flask were determined. A modification 
of Regnault and Reiset’s method was introduced by Jolyet and Reynard ;1° 
a stream of air was made to bubble slowly through the water in which the 


1 Berl. klin. Wehnsehr., 1887, S. 429; Arch. f. Physiol., Leipzig, 1889, S. 166. 

2 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1887, Bd. xxii. S. 368. 

3 Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xlii. S. 268 ; ibid., 1888, Bd. xliii. S. 519; 
ibid.. 1891, Bd. xlix. S. 492. 

+See p. 754. 

5 Sezelkow, Sitzungsb. d. k. Akad. d. Wissensch. Math.-naturw. Cl., Wien, 1862, 
Bd. xlv ; Kowalewsky, Ber. d. k. stichs. Gesellsch. d. Wissensch. Math.-phys. Kl., 1866, 
Bd. xviii. S. 111; Sanders-Ezn, ibid., 1867, Bd. xix. S. 58; Arb. a. d. physiol. Anst. zu 
Leipzig, 1868, S. 58; Scheremetjewski, Ber. d. k. stichs. Gesellsch. d. Wissensch. Math.- 
phys. Kl., 1868, Bd. xx. S. 154; Robrig and Zuntz, Arch. f. d. ges. Physiol., Bonn, 
1871, Bd. iv. S. 57; Zuntz, ibid., 1876, Bd. xii. S. 522; Finkler and Oertmann, ibid., 
1877, Bd. xiv. S. 38; Pfliiger, dbid., 1878, Bd. xviii. S. 247; Hanriot and Richet, 
Compt. rend. Soc. de biol., Paris, 1886 ; Compt. rend. Acad. d. sc., Paris, 1887, tome civ. 
p- 435; Fredericq, Rev. scient., Paris, 1880; Bull. Acad. roy. d. sc. de Belg., Bruxelles, 
1886. 

6 See p. 717. See also ‘*‘ Animal Heat,” this Text-book, vol. i. 

7 Mém..de la Soc. de phys. et de chim. d Arcueil, Paris, 1807, tome ii. p. 359; Journ. 
f. Chem. u. Phys., Niirnberg, Bd. i. S. 86. 

8 Journ. Physiol., Cambridge and London, 1895-96, vol. xix. p. 18. 

9 Chem. Untersuch. u. d. Respir. d. Schlammpeitzgers,” Breslau, 1855, S. 24. 

W Arch. de physiol. norm. et path., Paris, 1877, tome iv. p. 44. 


700 CHEMISTRY OF RESPIRATION. [ 

animal was placed ; this air was analysed for carbon dioxide, and the oxygen 
absorbed by the animal was replaced by a corresponding amount supplied from 
a gasometer. 

The consumption of oxygen by animals living in water can be determined 
by titrating a sample of the water before and after the confinement of the 
animal in a known volume of water. Quinquand! used for this purpose 
sodium hyposulphite, according to Schiitzenberger’s method. 


The conditions which affect the respiratory exchange. —— A de- 
termination of the respiratory exchange not only gives the absolute 
value of the oxygen absorbed, and of the carbon dioxide and water ex- 
creted, but also shows the relationship between the intake of oxygen 
and the output of carbon dioxide. This ratio between the volume of 
oxygen absorbed and the volume of carbon dioxide discharged is known as 
CO, 
0, 
bines with carbon to form carbon dioxide, for one volume of oxygen in 
combining with carbon yields one volume of carbon dioxide. Various 
conditions influence both the amount of the respiratory exchange and 
the relative proportions of the gases, but it must be remembered that 
determinations of short duration may give rise to erroneous conclusions, 
for oxygen may be stored up for some time within the body, and 
carbon dioxide may still be formed and discharged when there is no 
intake of oxygen. 

The question here arises, Does nitrogen play any active part in 
respiration, is there any absorption or discharge of nitrogen ?? The 
older observers found that nitrogen was sometimes absorbed by the 
lungs, and in nearly all of Regnault and Reiset’s? determinations of the 
respiratory exchange in different animals there is an alteration in the 
amount of nitrogen present in the air, denoting generally a discharge of 
a small quantity of nitrogen from the animal. Marchand * had also ob- 
tained similar results; he found in ten experiments upon guinea-pigs 
that the average discharge of nitrogen was equal to 0-94 per cent. of the 
output of carbon dioxide, and in three experiments on pigeons to 0°85 
per cent. Seegen and Nowak® also found a discharge of nitrogen, 
varying from 4 to 9 merms. per kilo.and hour in thirty-two experiments 
upon rabbits, dogs, and hens. 

This discharge of nitrogen in many cases appears to be due to an 
error of experiment.® Analyses, purposely made by Colasanti? to test 
this point, showed no discharge or absorption of nitrogen by guinea-pigs. 
The small amount observed by other experimenters may be due either 
to mitrogen discharged from the alimentary canal or to experimental 
errors. According to Jolyet, Bergonié, and Sigalas$ an amount of 
nitrogen varying from 735 to 7,%;5 of the oxygen absorbed is taken 
up by the blood in its passage through the lungs of a man or a dog. 
In any case the amount of nitrogen absorbed or discharged under 


the respiratory quotient , and indicates how much of the oxygen com- 


1 Compt. rend. Acad. d. sc., Paris, 1873, tome Ixxvi. p. 1141. ; 

° For further details, see Voit, Hermann’s ‘‘ Handbuch,” Bd. vi.; Th. 1, S. 37. 

3 Ann. de chim. et phys, Paris, 1849, Sér. 3, tome xxvi. 

4 Journ. f. prakt. Chem., Leipzig, 1848, Bd. xliv. S. 1. 

5 Sitzungsb. d. k. Akad. d. Wissensch.. Math.-naturw. Cl., Wien, 1875, Bd. lxxi. (3), 
S. 329 ; arch. f. d. ges. Physiol.. Bonn, 1879, Bd. xix. S. 347. 

6 Pettenkofer and Voit, Ztschr. f. Biol., Miinchen, 1880, Bd. xvi. S. 508. 

7 Arch. f. d. ges. Physiol., Bonn, 1877, Bd. xiv. S. 92. 

8 Compt. rend. Acad. d. sc., Paris, 1887, tome cv. p. 675. 


EXCHANGE OF COLD-BLOODED ANIMALS. 701 


ordinary conditions is so small that it may be neglected. It is to 
be noted, however, that Colasanti and Finkler? always found small 
quantities of marsh gas and hydrogen in the respiration chamber 
in which well-fed guinea-pigs were placed; these gases probably 
came from the alimentary canal, for they were not found in the case 
of guinea-pigs deprived of food. Zuntz? and Tacke found that three- 
quarters of the hydrogen and marsh gas formed in the alimentary 
canal of a rabbit were absorbed by the blood and discharged by the 
lungs. 

The respiratory exchange of cold-blooded animals. — When 
compared with warm-blooded animals, the respiratory exchange of 
most cold-blooded animals is very small, a fact which explains the 
small production of heat observed in this class of animals.2 Some 
of the earliest determinations were those made by Vauquelin,* 
Spallanzani,? Newport,® Treviranus,’ Edwards’ and Miller... They 
showed that the quantity of oxygen consumed and of carbon dioxide 
produced was for equal weights of animals generally much less in cold- 
blooded than in warm - blooded animals, the most marked exception 
being in insects. Later researches have confirmed these general conclu- 
sions, and have shown the conditions, which chiefly affect the respiratory 
exchange in these animals. Of these conditions the most important is 
the external temperature, a rise in temperature causing an increase, a 
fall in temperature a decrease in the respiratory exchange. In the 
following table the results of various observers are expressed for 
1 kilo. weight of animal and 1 hour, in order that they may be 
comparable :— 


za 33 [ Be 8) fa AS. x 
2 aga Z $ 
sa Ane oe! 2 Fs | f 
Animal. oO St = 5 Remarks. Observer. 
Sst <a 3 = 
5 Om 2 = 
| sy =LS 5 a 
3 0 | 
| * 
| | 
PRoTOzOsA— 
| Collozoum inerme.| .. a: ‘1113—s | 1°06 16° One determination. | Vernon.10 
| | | 
C@LENTER ATA— | 
Carmarina has-| .. ole 0087 ~—_ «| 1°10? 16° The determinations | re 
7 0 
tata | | of CO, show va- 
| | | 8 O, 
| } riations from ‘36 | 
: aed A to 2°16. 
| Cestusveneris .| .. ae 0037 "79? 16° | CO, : ” 
| | 2 varies from | 
| O2 -07 to 2-06. | 


1 Arch. f. d. ges. Physiol., Bonn, 1877, Bd. xv. S. 603. 

* Arch. f. Physiol., Leipzig, 1894, S. 354. See also this article, p. 729. 

8 Article ‘‘ Animal Heat,” this Text-book, vol. i. p. 792. 

4 Ann. de. chim., Paris, 1792, tome xii. p. 273. 

°“*Meém. sur la respiration,” par Senebier, 1803, p. 184; Journ. f. Chem. Physik. 
uw. Min., Berlin, Bd. iii. S. 378. 

6 Phil. Trans., London, 1837, pt. ii. p. 253. 

7 Zischr. f. Physiol., 1832, Bd. iv. S. 23. 

8 «* De l’influence des agens physiques sur la vie,” Paris, 1824. 

®« Klements of Physiology,’’ trans. Baly, 1838, vol. i. p. 310. 

0 Journ. Physiol., Cambridge and London, 1895-96, vol. xix. p. 18. 


CHEMISTRY OF RESPIRATION. 


702 
TABLE—continued. 
™ s | 
5 NS . 
oid tes 5 g 
bu sa 2 Lua 5 
no) ® =] Os : 3 
Animal. Se ) be Se Se Se CO, * Remarks. Observer. 
Cle) ae) oS oot VU a 
Se Ooms Sae S 
cS a -od BMC ® 
5 os Z 
| 
VERMES !— 
Lumbricus . 12 | O03 02108 77 2 Regnault and 
(708 c.c.) | (54:9 c.c.) | Reiset. 2 
3 3 |  0°593 18°-19° | One determination. | Pott. 
Hirudo 0°645 16°-19° | Mean of two deter- si 
(328 cc.) minations. 
Hirudo officinalis | 2°2 | 00328 070312 | -69 13°°5 | Before Jolyet and 
| (22°98 c.c.) | (159 c.c.) athe Regnard.+ 
Ss a | 00567 00701 -90 13° After ; sn 
| (39°70 c.c.) | (35°7 ec.) 
INSECTA— 
Antherea (18) 42°5 0840 | —0'916 79 u Regnault and 
(588 ¢.c.) | (465°7 c.c.) Reiset. 
” ” 39 0°687 | 0°767 “Sl v4 ” 
(480 c.c.) | (890°7 c.c.) 
35 42) 40 17170 17189 73 ? 3 
(818 c.c.) | (604'5 ¢.c.) 
Melolontha  (40)| 40°3 1:076 171699 “79 2 = 
| (752 c.c.) | (594°8 e.c.) | 
* (37) | 37 0-962 1°092 +82 ? 4 
(673 c.c.) (555 c.c.) 
Geotrupes 0°32 =. 17130 20°-21° | Mean of two deter- | Pott. 
(574 ¢.c.) | minations. 
Melolontha . 2°0 0°987 15°-17° | Larva. Meanoffour)| ,, 
| (503 c.c.) determinations. 
Locusta 0°839 16°-19° | Mean of threedeter-| ,, 
| (427 c.c.) minations. 
Gryllus campes- | 0°25 2°305 r Be “4 
tris (1172 c.c.) 
oA L 0°05 VS Gaby 17°-21° | Mean of two deter-| ,, 
(1081 c.c.) minations. 
Blatta orientalis . | 0-268 15°-20° es Biitschli.® 
‘ :, | 17045 30°-35° a 
| 
MOoLLusca— 
Octopus vulgaris 2310 “0630 “O745 “86 15°°5 Jolyet and 
(44"1 c.c.): | (Bis9ieie:) Regnard. 
33 aA = 1115 | “95 16° Vernon. 
Tethys leporina “0165 | ~=“84 16° ” 
| 
CRUSTACEA— 0543 0642 — 
Astacus fluvialis .| 31 (38c.c.) | (82°7¢.c.) | :86 | 12°°5 Jolyetand 
x3 ae Regnard. 
Gammarus pulex (132 c.c.) (95 c.c.) 72 12°°5 % 
Palemon squilla . (125:e.c.) | 03:8 c:e:) | :83 19° = 
Cancer pagurus .| 470 (107 c.c.) (89°9 c.c.) | 84 16° ; 
Homarus vulgaris | 315 | (68c.c.) | (544¢.c.) | °80 ate 
Palinurus quad-| 520 | (442c.c.) | (88°9¢.c.) | “88 15° 
ricorn 
} 


1 For experiments upon the respiration of nematoid worms, see Bunge, Zéschr. f. 
physiol. Chem., Strassburg, 1883, Bd. viii. S. 48; 1890, Bd. xiv. S. 318. 


2 Ann. de chim. et phys., Paris, 1849, Sér. 3, tome xxvi. 


3 Landwirthsch. Versuchsstat., Bd. xviii. S. 81. 

4 Arch. de physiol. norm. et path., Paris, 1877, tome iv. p. 44. 

° Butsehli, Arch. f. Anat., Physiol., w. wissensch. Med., 1874, 8S. 348. For further details 
on the respiratory exchange of insects, see Spallanzani, Journ. f. Chem. Physik. u. Min., 
Berlin, Bd. iii. S. 378 ; Vauquelin, Ann. de chim., Paris, 1792, tome xii. ; Treviranus, Ztschr. 
f. Physiol., 1832, Bd. iv. S. 23; Newport, Phil. Trans., London, 1837, pt. ii. p. 259; Detmer, 
Landwirthsch. Versuchsstat., Bd. xv. 8. 196 ; Liebe, Jahresb. ii. d. Fortschr. d. Thier-Chem., 
Wiesbaden, 1872, S. 332 ; Schmidt-Schwedt, Berl. entomol. Ztschr., Bd. xxxi. S. 325. 


Animal DET | 
L25 | 
ae! 
PIScES— 
Cyprinus ura- | 12-14 | 
tus | 
55 3 12-14 | 
“5 rf 33-40 | 
Cyprinus tinca .| 222 
” ” 500 
” ” 190- 
223 
Cyprinus carpio .| 12 
Cobitis fossilis | 43-61 
2° ” 16 
Murenaanguilla | 51 
” » 112 | 
| 
Mullus : -| 28 
Sparus auratus .| 75 | 
Trigla hirundo .| 350 
Murena conger .| 545 | 
Raja torpedo 315 
AMPHIBIA— 
Azolotl : -| 42 
Rana esculenta 
” 9 
” ” 
” ” 
5, temporaria 13°9 
” ) = 
“: os 31°64 
» » 31-64 
” ” | 34°47 


An examination of the above results shows that the respiratory 
exchange of most of the cold-blooded animals is very small, but that a 
marked exception exists in the case of insects, which have a metabolism 
equal to that of the larger mammals. 
confirmation in the relatively high temperature * of insects and in their 


793 
TABLE—continued. 
= = 
° Con) 5 
mA BoA = 
Eze ee Awe 
Se ABE CO, Fue) ail Remarks. Observer. 
Kee eco Os a 
T2Ze 226 S| 
: 35 Bl al | 
9 ror 
“0376 “0411 “79 8° | Fasting. Baumert. ? 
(26°3 c.c.) | (20°9 c.c.) 
0590 0617 ‘76 | 11°-12° | Fasting. Mean of 5 
(41°3.c.c.) | (3174 c.c.) three determina- | 
tions. 

0655 “064 aa 12° Mean of two deter-  Jolyet and 
(45°8 c.c.) | (82°7 c.c.) minations. Regnard. 
“0796 “0721 66 14° te Gc 

(55°7 c.c.) | (86°7 c.c.) 
“1001 a5 2? Quinquand. * 
(70°0 c.c.) 
“0165 “0159 “70 5° Baumert. 
(11°53 ¢.c.) | (8°09 c.c.) 
x 0°352 13°-14° | Young. Mean of two | Pott. 
(179 c.c.) | determinations. 
0455 0633 1°01 | 9°-12° | Mean of six deter- | Baumert. 
(31°8 c.c.) | (3272 ¢.c.) | minations. 
"1234 "1323 “78 | 17°-22° | a5 Jolyetand 
(86°3.c.c.) | (67°3 c.c.) Regnard. 
“0580 0629 “79 14° * 
(40°5 ¢.c.) (82 ¢.c.) 
“0686 “0566 “60 15° 5 
(48°0 c.c.) | (28°8 c.c.) 
“1916 2132 “81 14° st 
(134 ¢.c.) | (108°5 c.c.) 
*2031 1787 “64 19° 5 
(142 c.c.) | (90°9 c.c.) 
1351 1337 $7] 15° a 
(94°5 c.c.) (68 c.c.) 
“0855 “0865 “72 13° Le 
(59°8 c.c ) (43 c.c.) 
0672 0540 "D8 14°5° | Mean of two deter- # 
(47°0.c.c.) | (27°75 c.c.) minations. 
0646 “0497 “56 TIs:5 Jolyet and 
(45:2 c.c.) | (25°3:¢.c.) Regnard. 
063 0-060 “69 | 15°-19° +s Regnault and 
(44:2 c.c.) | (30°76 c.c.) a ae eee 
“105 071134 78 imal of five ex- 
(73°4 c.c.) | (87°7 e.c.) ee 
(50°46 c.c.) | (47°98 c.c.) | °95 Mine Oertmann. 
se 0-082 ne ye Schulz.* 
0°355 19°-20° 33 Pott. 
07502 23°71 | Mean of twenty-two Moleschott. 
experiments. 
07038 13° Duration of ex- | Pembrey. 
periment was 
- three and four 
07035 ney hours (winter 
frog). 
0°033 12°°5 | Winter frog Vernon. 


wonderful muscular activity. 


This remarkable exception finds 


1“Chem. Untersuch. u. d. Respir. d. Schlammpeitzgers,” Breslau, 1855, S. 24. 
2 Compt. rend. Acad. d. sc., Paris, 1878, tome Ixxyi. p. 1141. 
3 Arch. f. d. ges. Physiol., Bonn, 1877, Bd. xiv. S. 78. 

4 Article ‘‘ Animal Heat,” this Text-book, vol. i. 


704 CHEMISTRY OF RESPIRATION. 


The respiration of fishes.—The necessity of air for the life of fishes 
was proved by Boyle! during his experiments with the air-pump. He states 
that ‘‘ there is wont to lurk in water many little parcels of interspersed air, 
whereof it seems not impossible that fishes may make some use, either by 
separating it when they strain the matter through their gills, or by some other 
way.” Mayow? (1674) appears to have been the first to understand and to 
correctly describe how fish breathed by taking up nitro-aerial gas (oxygen) 
from the water by means of the blood flowing through their gills; and Ber- 
nouilli? in 1690 demonstrated that fish could not live in cold water from 
which the air had been expelled by boiling. 

The methods employed and quantitative results obtained by different 
observers, who have studied the respiration of fishes and other animals living 
in water, have already been described. A few additional facts, however, 
must be mentioned. Humboldt and Provencal! state that nitrogen was in 
some cases absorbed, but when the water was impregnated with oxygen and 
hydrogen none of the latter gas was taken up by the fishes ; a certain amount 
of cutaneous respiration also occurs, and fishes can breathe in the air as long as 
their gills are kept moist with water. The respiration of fishes living in the 
sea is facilitated by the absence of any free carbon dioxide in the water, for 
any carbon dioxide formed is at once fixed by the excess of alkaline base 
present in the water.® 

In connection with the respiration of fishes, the swimméing-bladder must be 
considered, for this organ is one which can secrete gases and in some cases 
store up almost pure oxygen. 

Biot ® found that the percentage of oxygen increased with the depth from 
which the fish was taken; the greatest percentage was 87. This was con- 
firmed by the observations of Delaroche,’ who obtained 70 per cent. oxygen from 
the bladder of fishes drawn up from a greater depth than 50 metres (164 feet), 
and 29 per cent. from those taken at smaller depths. Erman,* Vauquelin,® 
Configliachi,!° and Delaroche!! analysed the gas in the swimming-bladder of 
fresh-water fish, and found the percentage of oxygen generally less than that 
in the atmosphere, little or no carbon dioxide, but much nitrogen. The mean 
of analyses made by Humboldt and Provencal showed 7:1 parts of oxygen, 
5:2 of carbon dioxide, and 87:7 parts of nitrogen in 100 volumes of gas from 
the swimming-bladder of a carp, while the results obtained by F. Schultz !? 
varied between 1:1 and 15:2 per cent. oxygen and 1°4 and 5-4 per cent. carbon 
dioxide. 

According to Humboldt and Provencal, the tench (Cyprinus tinea), in which 
there is a duct communicating between the air-bladder and the mouth, does 
not take hydrogen into its bladder when the water in which it is confined is 
saturated with that gas. Moreau obtained similar negative results ; but more 


1“ New Experiments, Physico-Mechanical, touching the Spring of the Air,” 1662; 
Phil. Trans., London, 1670, pp. 2011, 2035 ; ‘‘ Works,” Shaw’s edition, vol. i. p. 109. 

2 «<Tractatus quinque,”’ Oxon., 1674, vol. i. ch. xv. p. 259. 

3 *<Tissertatio de effervescentia et fermentatione nova hypothesi fundata,” ch. xiv. 
Basiliz, 1690. 

4 Mém. de la Soc. de phys. et de chim. @ Arcueil, Paris, 1809, tome il. p. 359; Journ. 
f. Chem. u. Phys., Niirnberg, 1811, Bd. i. S. 86. 
“5 Dittmar, Proc. Phil. Soc. Glasgow, vol. xvi. p. 61; M‘Kendrick, Nature, London, 
1888, Aug. 16; Brit. Med. Jowrn., London, 1888, vol. ii. p. 331; Petersen, Scottish 
Geograph. Mag., Edinburgh, 1895, June, p. 294. 

6 Mém. de la Soc. de phys. et de chim. d@ Arcueil, Paris, 1807, tome i. p. 252; Ann. d. 
Phys. u. Chem., Leipzig, Bd. xxvi. 8. 454. 

7 Journ. f. Chem. u. Phys., Niirnberg, 1811, Bd. i. S. 122. 

8 Ann. d. Phys. u. Chem., Leipzig, 1808, Bd. xxx. S. 113. 

9 Vauquelin, quoted from Erman, reference 8. 

W Journ. f. Chem. u. Phys., Niirnberg, 1811, Bd. i. S. 137. 

ll Tbid., S. 164. 

2 Arch. f. d. ges. Physiol., Bonn, 1872, Bd. v. S. 48. 


EXCHANGE OF COLD-BLOODED ANIMALS. 705 


recent experiments by Mengarini! show that the goldfish (Carassius auratus) 
and roach (Leuciscus), in which there is a ductus pneumaticus, the mullet 
(Mugil cephalus) and rockling (Motella), in which there is no duct, do take up 
hydrogen from water saturated with that gas. 

Moreau? has shown that the withdrawal of the gas of the swimming-bladder 
by means of a trocar leads in a short time to the secretion of a gas richer in 
oxygen, and that bya repetition of this process the percentage of oxygen can be 
raised as high as 85 ; he also states that section of the sympathetic nerve hastens 
the process “ot secretion. These observations have been repeated and extended 
by Hiifner* and Bohr.* Cod-fish (Gadus callarias) were caught in a net at a 
depth of about 14 metres (46 feet), and when they were drawn to the surface 
the gas in the air-bladder expanded so much that the fish swam with their backs 
downwards. The gas was found in one case to contain 52 per cent. of oxygen ; 
but when the fish had been near the surface of the water for some time only 13 
per cent. of oxygen was obtained. After the removal of the gas from the bladder, 
its secretion begins again ; within six hours a little gas has accumulated, and in 
twenty-four hours the bladder is again full. The rapidity of the process and the 
increase in the percentage of oxygen is shown by the following examples :— 


| ! 
Number of Hours after the Percentage Percentage of | 


Experiment. First Puncture. | of Oxygen. Carbon Dioxide. 


Remarks. 


} 0 15:0 atk | 8 c.c. of gas in the air-bladd2r. 
24 48 78°5 1:0 le Cl Gs) anes 55 
71 83°7 0°5 | 7 cc. a be | 
\ 0 15:0 é. 6 ce. ee “s 
25 50 78°4 0°8 5 eG: 5 - 
| 73 727 10 Soe) aa: s | 
= 0 16°3 0-1 
| 5 16°3 0:2 


{ 


Bohr has also shown that after section of the branches (rami intestinales) 
_ of the vagus which supply the air-bladder, the secretion of the gas ceases en- 
tirely, but that no effect upon the secretion is observed after section of the 
rami cardiaci or the nervi laterales. These phenomena observed in the case of 
the swimming-bladder can at present be explained only as a process of secretion. 
The air is not swallowed, for the fishes with the greatest percentage of oxygen 
in their bladders are those which do not come to the surface, but live at great 
_ depths ; in some of them, moreover, such as the cod (Gadus callarias), there is 
no communication between the bladder and the mouth. The phenomena can- 
not be accounted for by simple diffusion, for the water which surrounds the fish 
cannot have a higher tension of oxygen than 21 per cent. of an atmosphere.® 
Further, Bohr has shown that the percentage of oxygen is not reduced by 
diffusion outwards, for when the secretion of fresh oxygen is prevented by 
section of the vagus, the high percentage of oxygen is maintained for two or 
three days. As long as the swimming-bladder is fresh, it is almost im- 
permeable to oxygen, even when the difference of pressures inside and outside 
the bladder amounts to one atmosphere. It is to be noted that the membrane 
lining the swimming-bladder has a peculiar glandular structure. 


1 Arch. f. Physiol., Leipzig, 1889, S. 54. 

2 Compt. rend. Acai ass: Paris, 1873, tome lvii. pp. 37, 816; ‘‘ Recherches experi- 
mentales sur les functiones de la vessie natatoire,” Paris, 1876 ; “ Mém, de physiol.,” Paris, 
1877, pp. 69-86. 

3’ Arch. f. Physiol., Leipzig, 1892, S. 54. 

4 Journ. Physiol., ‘Cambridge and London, 1894, vol. xy. p. 494; Compt. rend. Acad. 
d. sc., Paris, 1892, tome exiv. p. 1560. 

5 Biot, Delaroche, Moreau, /oc. cit. ; Jakobsen, Ann. d. Chem. u. Pharm., Bd. elxvii. 
Sais Hiifner, Arch. 7 Physiol., Leipzig, 1897, S. 112. 


VOL. I.—45 


CHEMISTRY OF RESPIRATION. 


Table of the Respiratory Exchange of Warm-Blooded Animals. 


706 
| - Carbon 
Weight| OXS8en | Dioxide 
Animal. (in [Deus Ne per Kilo. 
and Hour 
Grms. ). (in Grms.) and Hour 
** | Gin Grms.). 
BIRDsS— 
Common Hen 1280 1°058 1°327 
(740 c.c.) (675 c.c.) 
7 34 1-057 1-403 
(739 c.c.) (714 c.c.) 
3 1578 17084 1°486 
(758 ¢.c.) (756 e.c.) 
ss 1546 1-067 1°447 
746 c.c.) (736 c.c.) 
5 1637 1109 1561 
Uirplerc.) (793°6) 
* 1820 ee "665 
3 1500 1-755 
Duck 1740 2-270 
Goose (4) 18,400 ‘677 649 
(A473 c.¢.) (330 ¢.¢.) 
ED) 2975 | 1-490 
Turkey-cock (2) . | 12,250 “702 791 
(490 c.c.) (402 c.c.) 
= ia) 2650 1°319 
Pigeon. 325 | 3-360 
A 232- 3°236 
380 
Turtle-dove 167 4-591 
( 25 13°000 13°590 ) 
, i (9091 c.c.) | (6909 c.c 
Eeeerineh i | 95 9°742 9-246 
(6813 c.c.) | (4701 c.c.) 
Goldfinch . 21°5 ie 12°582 
Sparrow. 22, 9°595 | 107492 
| (6710 c.c.) | (53345 cc.) 
¥ Rf: 25 | ¥ 7-783 
(3957 c.c.) 
Crossbill “ 28°6 10°974 12°014 
(7674 c.c.) | (6108°5 ¢.c.) 
MAMMALIA— 
Rabbit. . 2755 0°987 1°244 
(690 c.c.) (632 ¢.c.) 
iitek: 2780 0-877 1°107 
(613 c.c.) | (563 ¢.c.) 
Piessinvs lost) 22140 0°797 1°039 
(557 ¢.c.) (528 e.c.) 
Sic ae ee ea BS 1-012 1°354 
= . 1882 0°762 07943 
Tne = = 1931 0883 1°142 
Guinea-pig . 5 a LA 1°35 


co, 


Tempera- 
ture. 


16° 


18° 


Remarks. 


Fed on oats and 
water. 


Mean of 12 experi- 
ments on 2 hens. 

Mean of 7 experi- 
ments. 

Mean of 5 experi- 
ments. 

Determination 
lasted 25 hrs., 
no food given. 

Mean of 12 experi- 
ments. 

Determination 
lasted 183 hrs., 
no food given. 


| Mean of 5 experi- 


ments. 

Mean of 11 experi- 
ments. 

Mean of 10 experi- 
ments. 


Mean of 11 experi- 


ments on 3 
doves. 


- 


Mean of 3 experi- 
ments. 


Mean of two de- 
terminations. 


- 


Fed on swedes. 
3° 


Mean of 6 experi- 
ments. 


1 Ann. de chim. et phys., Paris, 1849, Sér. 3, tome xxvi. 
2 Arch. de physiol. norm. et path., Paris, 1890, tome xxii. p. 485. 
> Ann. de chim. et phys., Paris, 1863, Sér. 3, tome lxix. p. 129. 

E lal’: 
> Ann. de chim. et phys., Paris, 1844, Ser, 3, tome xl. p. 444. 
5 Landwirthsch. Versuchsstat., Bd. xviii. 8. 81. 
* Journ. Physiol., Cambridge and London, 1894, vol. xv. p. 449. 
8 Journ. f. vrakt. Chem., Leipzig, 1848, Bd. xliv. S. 1. 


+ Trav. du lab. de Liege, 1888, tome i. 


Observer. 


Regnault and 
Reiset.1 


” 


»” 


Richet.2 


” 


Reiset.$ 


Richet. 


Reiset. 


Richet. 


” 


Corin and Van 
Beneden.4 


Boussingault.® 


Regnault and 
Reiset. 


” » 


Richet. 


Pott. 


Regnault and 
Reiset. 


Pembrey and 
Giirber.7 


bel 


Marchand.8 


EXCHANGE OF COLD-BLOODED ANIMALS. 707 
TABLE—continued. 
Li. Carbon 3 
Weight Oxygen Dioxide Co, og 
Animal. (in per suc, | per Kilo. | “9, am Remarks. Observer. 
, and Hour 2 a5 
Grms.). (in Grms.) and Hour a+ 
-- | Gin Grms.). a 
MAMMALIA— 
Guinea-pig? : ae 1612 1°896 “86 18°8 ae Colasanti.1 
” . . | 444°9 1°478 1°758 ‘86 22° Duration of ex-| Pembrey, 
periment was 
2+ hours. 
” 6 - | 445°6 1°416 1°885 “96 20° ” ” 
Dog 6213 1°303 1°325 74 Die Fed on raw meat. | Regnault and 
(911 c.c.) (674 c.c.) Reiset. 
9 ry 5 6158 1°393 1°425 74 15° Ae ) 
(975 c.e.) (724 e.¢.) 
+ é 20,000- A 1026 748 Mean of experi- | Richet.? 
28,000 ments on 4dogs. 
» : 13,000- 1-210 ‘748 Mean of experi- ” 
14,000 ments on 5 dogs. 
fo oe Poe 1°380 748 Mean of experi- ” 
12,000 ments on 7 dogs. 
3 : 5 . | 8000- c 1-506 “748 Mean of experi- ”» 
10,000 ments on 4 dogs. 
suet. | sc! '6000= 1°624 748 Mean of experi- | 2 
7000 ments on 3 dogs. 
9 ° r = 4700- 1°688 “748 ” ” 
5600 
arid a 2 . | 2800- 1°964 ‘748 Mean of experi- ” 
3800 ments on 6 dogs. 
a3 5 . | 2200- 2°650 “748 Mean of experi- ” 
2500 ments on 4 dogs. 
29 - : . | 34,000 0°709 Leyden and 
Frankel.4 
» . 33,000 0-668 Mean of 17 experi-| Pettenkofer 
ments. and Voit.4 
” . 18,000 1°230 - Gréhant and 
Quinquand.6 
” 6750 0°939 | Wood.7 
| 
5 5300 0°690 Mean of 9 experi- | Senator.8 
ments. 
” 5200 1288 Mean of 7 experi-| Bauer and 
ments. Beeck.9 
os 4000 1126 Mean of 4 experi- | Page.10 
ments. 
Cat 2464- 1°356 1:397 -3°°2 ‘Carl Theodor.11 
3047 (947 c.c.) (710 c.c.) 
» 9 0°645 0-766 29°°6 we ” 
(450.c.c.) | (889 e.c.) 
os BS 1-364 Liberal diet of | Bidder and 
(693 c.c.) meat. | Schmidt.12 
aa 1°42¢ ” ” 
723 €.C.) 
Sheep . 66,000 0-490 0°671 99 16° Exprmnt. lasted Reiset. 
(343 c.c.) (341 c.c.) 141 hours; no 
food during 
that time. 
nO - pA 0°733 ay | Henneberg.1% 
Osea ae 638,000- 0°389- Bs 
660,000 0°485 
9 . 710,000 0°488- ~~ ” 
0-616 | 


1 Arch. f. d. ges. Physiol., Bonn, 1877, Bd. iv. S. 92 and 469. 
2 See also Finkler, ibid., Bonn, 1877, Bd. xv. S. 603. 
3 Compt. rend. Acad. d. sc., Paris, 1889, tome cix. p. 190; Arch. de physiol. norm. et 
path., Paris, 1890, tome xxii. p. 17. 


4 Virchow’s Archiv, 1879, Bd. xxvii. S. 136. 


> Zischr. f. Biol., Miinchen, 1873, Bd. ix. S. 1. 
§ Journ. de Vanat. et physiol., etc., Paris, 1882, tome xviii. p. 469. 
7 Fever, Smithson. Contrib. Knowl., Washington, 1880. 


8 Arch. f. Anat., Physiol., u. wissensch. Med., 1872, S. 1. 


® Ztschr. f. Biol., Mimchen, 1874, Bd. x. S. 341. 

0 Journ. Physiol., Cambridge and London, 1879, vol. ii. p. 228. 

Ul Zitschr. f. Biol., Miinchen, 1878, Bd. xiv. S. 51. 

2 *«Die Verdauungssafte und der Stoffwechsel,” Leipzig, 1852, S. 321-362, 

13 Landwirthsch. Versuchsstat., 1866, Bd. viii. S. 443; ‘‘ Neue Beitr. z. Begriindung 
einer rationellen Fiitterung der Wiederkiuer,” Gottingen, 1870-72. 


CHEMISTRY OF RESPIRATION. 


708 
TABLE—continued. 
= Carbon 
Weight) OX}8e" | Dioxide 
Animal. (in ae HK oS per Kilo. 
Grms. ). dn Catan). and Hour 
S-)- (in Grms.). 
MAMMALIA— 
Boar 135,000 | 0°391 0°443 
(273 c.c.) (225 ¢.c.) 
Sow 105,000 0°561 0°661 
(392 ¢.c.) (336 ¢.c.) 
Rat (white) . 80°5 Bs 37518 
(1789 c.c.) 
» (grey). 55°5 4°308 
; (2190 e.c.) 
Mouse (white) 13 8880 
(4514 ¢.c.) 
” ” 25 84 
»> (common) 19°2 6°660 77443 
Man 70,000- 0-41 
73,000 
” ” 0°61 
” ” 0-76 
” 71,000- 0°373 
74,220 
” ” 0°52 
” 65,500 0°512 
ta 82,000 0°497 
” 57,750 0594 
s . |57,000-| 0°601 0-717 
| 60,000 | (420¢.c.) | (864 ¢.c.) 
- * 0-461 0°535 
(322 c.c.) 271 c.c.) 
” ” 0°516 0°619 
| (861 c.c.) (314 c.c.) 
We | 50,000 17,000 c.c. | 13,000 c.c. 
a “5 16,000 ,, 13,300 ,, 
” ” 18,200 ,, | 13,550 ,, 
va 67,500 | 222°9 ,, | 202°7 ,, 
ie 60,500 | 247-2 ,, | 1961 ,, 
ae é 59,000 | 3°53 y, 2°88 ,, 
a ¢. 96,000 SEU 228 ,, 
72,000 cle 3°47 ,, 


va 
bo 


"85 


“80 


z 
2.9 
Be Remarks. 
a5 
o~ 
i= 
16° Exprmnt. lasted 
133 hrs.; food 
during the ex- 
periment. 
17°°9 > 
ff | 
16° 
ha 
17° 
10°°5 
Minimum and 
maximum in| 
24 hrs.; man 
at rest. 
Man at work. 
Hunger. 
Very liberal diet. 
Max. 
Of 
Min; | 412 
experi- 
Mean | ments. 
sek hour La 
| 50 kilos. 
Hunger(perminute 
and 673 kilos.). 
Hunger(per minute 
and 603 kilos.). 
14°- 
ee is Man at rest 
199 |; (per kilo. and 
17°-5- | minute). 
19°°2 


1 Journ. Physiol., Cambridge and London, 1894, vol. xv. p. 401. 
2 Arch. ital. de biol., Turin, 1891, tome xv. p. 223. 


3 Ann. d. Chem. u. 


Observer. 


Reiset. 


Pembrey.1 


| Oddi.? 


Pettenkofer 
and Voit.3 


” 


Ranke.4 


” 
Scharling.5 


” 


” 


Hanriot and 
Richet.7 


Lowy.8 


” 


Geppert.9 
” 


” 


Pharm., 1867, Bd. exli. S. 295; Ztschr. f. Biol., Miinchen, 


1866, Bd. ii. S. 459 ;.1869, Bd. v. S. 319; Sitzwngsb. d. k. Akad. d. Wissensch., Wien, 
Nov. 10, 1866; Feb. 9, 1867. 
4 Arch. f. Anat., Physiol., u. wissensch. Med., 1862, S. 311. 


5 Ann. d. Chem. u. Pharm., 1843, Bd. xlv. S. 214. 


8 «‘Untersuch. ueber Sauerstoffverbrauch. u. Kohlensiureausathmung des Menschen,” 
Cassel, 1871, S. 31. 


7 Compt. rend. Acad. d. sc., Paris, 1888, tome evi. 


p. 419. 


8 Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xiii. S. 523, 524. 
9 Arch. f. exper, Path. u. Pharmakol,, Leipzig, 1887, Bd. xxii. S. 381. 


EXCHANGE OF WARM-BLOODED ANIMALS. 709 


The respiratory exchange of warm-blooded animals.—The 
tissues of warm-blooded animals are the seat of a very energetic 
combustion, which is subject to quantitative and qualitative changes, 
owing to the influence of certain factors, such as age, size of body, 
external temperature, muscular activity, rest, digestion, hunger, and 
hibernation. A general comparison between the various members of 
the two great classes of the warm-blooded animals, birds and mammals, 
will be found in the tables on pp. 706-708. 

These tables! show that, weight for weight, birds have a more 
rapid respiratory exchange than mammals, and this difference is 
associated with a higher bodily temperature? It is also to be 
noticed that the respiratory quotient of the herbivorous animals is 
nearly unity, but that of the carnivorous animals is about 0°74. 
The respiratory exchange of small animals of the same or of 
different species is relatively greater than that of large animals.® 
The causes of many of these differences will now be discussed in 
detail. 

The influence of external temperature upon the respiratory ex- 
change.—Since the time when Crawford+ showed by experiment that 
external cold increased the discharge of carbon dioxide from a warm- 
blooded animal, numerous similar observations have been made by various 
observers. The most important result of this work has been the dis- 
covery that cold-blooded animals respond to changes of external tempera- 
ture in an exactly opposite way to that shown by warm-blooded animals ; 
in the former class a rise or fall in the temperature of the surroundings 
produces respectively an increase or decrease in the intake of oxygen 
and the output of carbon dioxide, whereas in the latter class cold increases 
and heat diminishes the respiratory exchange. On this account it will 
be well to consider separately the influence of temperature on these two 
classes of animals, and then to discuss the causes of the great difference 
in the effect. 

Cold-blooded animals.—Some of the earliest experiments upon the 
influence of temperature upon the respiratory exchange of cold-blooded 
animals appear to have been made by Delaroche,? Treviranus,® and 
Marchand,’ but, owing to imperfect methods, their results are not very 
exact, although they show that the respiratory exchange slowly rises 
and falls with the external temperature. 

In 1857, Moleschott * made a series of experiments upon frogs, and 
found that exposure to an increased external temperature or to light 
caused an increase in the output of carbon dioxide. 

Regnault and Reiset ® made three observations upon the respiratory 
exchange of green lizards at different external temperatures, and obtained 
the following results :— 


1 Further data will be found in the article by Zuntz, Hermann’s ‘‘ Handbuch,” Bd. iv. 
_ Th. 2, S. 129, from which many of the figures in the above tables have been taken. See 
also tables in paper by Richet, Arch. de physiol. norm. et path., Paris, 1891, tome xxiii. 


p. 74. 
* Article ‘‘ Animal Heat,” this Text-book, vol. i. p. 791. 
5 See p. 720. 


4**Qn Animal Heat,’ London, 1788, pp. 311, 387. 

> Journ. de phys. de chim., ete., Paris, 1813, tome Ixxvii. p. 5. 

6 Ztschr. f. Physiol., 1831, Bd. iv. S. 1. 

” Journ. f. prakt. Chem., Leipzig, Bd. xxxiii. S. 152. 

*8 Untersuch. z. Naturl. d. Mensch. u. d. Thiere, 1857, Bd. ii. S. 315. 
° Ann. de chim. et phys., Paris, 1849, Sér. 3, tome xxvi. 


710 CHEMISTRY OF RESPIRATION. 


| Oxygen | Carbon Dioxide | GQ, | imagens Terie 
Weight. per Kilo. and | per Kilo. and 02 \ res Kilo aie Remarks, 
| Hour. Hour. ri A aye yi 
; Grms. | Grms. C.c. | Grms. C.c. C.c. J j 
3 lizards, 68°5 | 0°0246 17:°2/0:°025 12°6 |°73| 5:732 7°°3 | Hibernating. 
| - 
Ap 42 0°0646 45°2 0:063 O20 a ae 1°905 14°°8 | Half awake. 


bo 


ho OZ OT OTGedts4s0 102099) 100s%ia) efile 2249 23°°4 | Awake and well ; 
| fed for a month. 


There are, however, several conditions which prevent these results 
from being considered comparable; the hibernating? animal has a very 
low respiratory exchange, even when the external temperature is higher 
than 7°°3; in the last experiment the food would increase the respira- 
tory exchange; the observations were made at intervals of several 
months, and are complicated by the large discharge of nitrogen, which 
is probably to be attributed to an error of experiment.” 

Biitschli® showed that the respiratory exchange of insects varied in 
the same direction as the temperature of their surroundings. 

The most complete series of observations appear to be those of 
Schulz * upon the edible frog (Rana esculenta). The following table 
gives his chief results, obtained upon frogs in summer :— 


| | 
ot the Recpiration | Temperature |. yax‘eiio, and Hout, | per Kalo, andl our 
Chamber. se C.c. at 0° and 760 Mm. | in Grms. 
0°-0 ib30) 4°31 00084 
0°°25 ea 6°097 0°0119 
0°°8 195) 7°50 0°0147 
Grol 6°°4 34°17 0°0672 
15°°8 15°°4 35°30 0°0694 
AD) Tey 41°83 0°0822 
25°°5 25°°0 76°26 071499 
25°°5 Zone 86°75 0°1706 
33°°0 33°°0 279°40 0°5495 
Some Som 314°53 0°6179 
34°°2 33°°5 340°48 0°6696 
35°°0 34°°0 


325°05 0°6392 


It is to be noted that in Schulz’s experiments the frogs were kept in 
the warm or cold surroundings until their temperature was equal to 
that of the air, so that the results are strictly upon frogs at different 
temperatures. The response of a frog, as shown by its temperature and 
respiratory exchange, to a change of external temperature is very slow, 
and for this reason observations upon the metabolism of cold-blooded 
animals can only be properly compared when the temperature of the 
animal and that of the air are known. The above results show that at 
temperatures a degree or two above zero the output of carbon dioxide 


1 See ‘‘ Animal Heat,”’ this Text-book, vol. i. 

2 See also Pfltiger, Arch. f. d. ges. Physiol., Bonn, 1877, Bd. xiv, 8. 73. 
3 Arch. f. Anat., Physiol., u. wissensch. Med., 1874, S. 348. 

4+ Arch. f. d. ges. Physiol., Bonn, 1877, Bd. xiv. S. 78. 


WARM-BLOODED ANIMALS. 711 


is very minute, and rises with the temperature, until at 34° the output 
is, weight for weight of body, equal to that of a man. 

The observations of Pembrey! and Vernon* seem to show that the 
output of carbon dioxide in frogs (Rana temporia) does not increase in 
exact proportion with the temperature. 

Warm-blooded animals.—Since the first experiments by Crawford? 
in which it was shown that a guinea-pig produced more carbon dioxide 
in cold than in warm surroundings, numerous observations * have been 


| | 
| | | | 
Carbon-Dioxide Water | | 
Tempera-| Oxygen absorbed |~™,- P | CO2|COz | | 
Animal. | ture of | perKilo. and | ‘scharged discharged |“) Observer. 
Air. Hour. and Hour. | and Hour. } 
C.c. | C.c. 
: Bef), 152-5 1079°66 1065°92 BP ce eee 
pee = \) 67-0 1438°31 | 1262-67 act + 118 Biliczs II et Gne 
yee: 1050-00 867°19 Te an Opa a2 9 aoe 
” \| 63 | +1592°33 1230-00 = ‘79 | 
f\ 3°°64 1856°50 | 155480 |... “s3i| 28) bg 
2 \, 26-21 | 111850 | 1057-40 res ani | cds od fin eet 
[ide sepad o | 
| eee 
Grms. Grms. | Grms. 
a 9-030 9°505 6705 |°76)1°4 
Mouse ; 5° 8°384 8-641 | 6°721 | °74)1-2 | 
weightabout- 10°°5 6°660 7°443° | «5079 | 80} 1-4) } Oddi.” 
19 grms. 25° 4°862 5-400 | 5102 | 80} 1-0| 
| 35° 5912 4977 | 4°736 | °65/1-0 
. f| -9° bak OS UG ie ... | ...| Corin and Van | 
teen Beli s Bo | 17141 Aes3i| Eee | Beneden.® 
| | 
[ime | Grms. Grms. Grms. 
( eo | EDI Le az-0s | 14-12 ||) 4 | 
Pere 88 EBs) VETER LE “48-99 10°87 | «| ee | L 9 | 
| 18°°0 | 42-30 13-93 10°60 +. | + | Carl Theodor 


29°°6 13-91) , 18:12 1948 | + | os 
Se 

For periods of six hours, cat weighing | 
| 2557-2650 grms. The figures are) 


not reduced to kilo. and hour. bigs} 


1“ Proce, Physiol. Soc.,” Journ. Physiol., Cambridge and London, 1894, vol. xvi. 

2 Journ. Physiol., Cambridge and London, 1894-1895, vol. xvii. p. 277. 

3 On Animal Heat,” London, 1788, pp. 311, 387. 

4 Delaroche, Journ. de phys. de chim. etc., Paris, 1813, tome lxxvii. p. 5; Vierordt, 
‘Physiol. des Athmens,” 1845; Wagner's ‘‘ Handworterbuch,” 1844, Bd. ii. S. 828; 
Letellier, Ann. de chim. et phys., Paris, 1845, Sér. 3, tome xiii. p. 478 ; Lehmann, Abhandi. 
d. k. stichs. Geselisch. d. Wissensch., Leipzig, 1846, 8. 463; Liebermeister, Deutsches Arch. 
f. klin. Med., Leipzig, 1872, Bd. x. S. 89, 420; Gildemeister, Virchow’s Archiv, Bd. lii. 
S. 130; Sanders-Ezn, Ber. d. k. séchs. Gesellsch. d. Wissensch. Math.-phys. Cl., Leipzig, 
1867, S. 58; Rohrig and Zuntz, Arch. f. d. ges. Physiol., Bonn, 1871, Bd. iv. S. 57; 
Pfliiger, ibid., 1876, Bd. xii. S. 282; Regnault and Reiset, dun. d. Chem. u. Pharm., 
1850, Bd. Ixxiii, S. 260; Berthollet, Mém. de la Soc. de phys. et de chim. d Arcueil, Paris, 
tome ii.; Senator, Arch. f. Anat., Physiol., wu. wissensch. Med., 1872, S. 1; 1874, S. 42, 
54; Centralbl. f. d. med. Wissensch., Berlin, 1871, Nos. 47 and 48; Erler, Arch. f. Anat., 
physiol., uw. wissensch. Med., 1876, S. 556 ; Litten, Virchow’s Archiv, 1877, Bd. lxx. S. 10; 
Fredericq, Arch. de biol., Gand, 1882, tome iii. pp. 736, 743; Quinquand, Compt. rend. 
Acad. d. sc., Paris, 1887, tome civ. p. 1542. 

5 Arch. f. d. ges. Physiol., Bonn, 1877, Bd. xiv. S. 92. See also Pfliiger, cbid., 
S. 469. 

6 Thid., 1877, Bd. xv. S. 603. 

7 Arch. ital. de biol., Turin, 1891, vol. xv. p. 228. 

8 Arch. de biol., Gand, 1887, tome vii. p. 265. 

® Ztschr. f. Biol., Miinchen, 1878, Bd. xiv. S. 51. 


712 CHEMISTRY OF RESPIRATION. 


made upon the influence of external temperature upon the respiratory 
exchange of warm-blooded animals. The general result of this work is 
that the intake of oxygen and the output of carbon dioxide increase 
with a fall and decrease with a rise of external temperature. This is 
shown by the examples, which have been taken from the results obtained 
by different observers, and are given in the preceding table. 

It appears that, when the external temperature is raised to a point 
about 30°, the respiratory exchange shows an increase above the amount 
observed at a temperature of 20°. Thus Voit! found in the case of a 
man, that the output of carbon dioxide was increased by a fall of 9° or 
10° below the average temperature 14°15’, and also increased by a rise 
of 15° or 16° above that point; the augmentation in the discharge of 
carbon dioxide was respectively 36 per cent. and 10 per cent. above that 
given off at 14°-15°. A similar result was obtained by Page,2 who 
found that at a temperature of 25° the discharge of carbon dioxide by a 
dog was at a minimum; a fall or rise of 10° below that point produced a 
mean increase of 31 per cent. and 51 per cent. respectively.2 Unfortun- 
ately Voit gives no details as to the temperature of the man during 
the experiments, but in one or two cases Page notes that the tempera- 
ture of the dog was raised above the normal by exposure to the 
warm air. 

The earliest experiments upon the influence of external temperature 
on the respiratory exchange of man were made by Lavoisier and Seguin, 
who found that a man at rest absorbed in an hour 34:49 grms. of 
oxygen when the air was 32°, but 38°31 grms. when the temperature 
was 15°. Since that time many observations® have been made upon 
man and the effect of external temperature on his respiratory exchange, 
and of these the most important are those made by Lowy.® The 
general result drawn from his experiments is that the effect of external 
cold varies in different men. Out of fifty-five experiments, the oxygen 
absorbed was increased above 5 per cent. in twenty-six cases, unaltered in 
twenty, and diminished in nine cases. In these experiments, in which the 
metabolism was increased, for the variations in the output of carbon 
dioxide followed those in the absorption of oxygen, the heights to which 
it was raised varied between 5 and 90°8 per cent. above the normal. A 
point worthy of note is that the greatest increase in the respiratory 
exchange was observed in the men who shivered or moyed when they 
felt cold, and that the respiratory exchange remained unaltered or 
decreased in the men who, notwithstanding the sensation of cold, 
remained quiet, and by an effort of the will suppressed any tendency to 
move or shiver. Lowy concludes that the only involuntary regulator 
of temperature in a man exposed to moderate cold is the skin. It must 
be pointed out, however, that increased muscular activity in a man who 


1 Ztschr. f. Biol., Miinchen, 1878, Bd. xiv. S. 80. 

* Journ. Physiol., Cambridge and London, 1879-80, vol. ii. p. 228. 

*See also Rubner, ‘‘Biologische Gesetze,” Universitats-programm, Marburg, 1887 ; 
abstract in Centralbl. 7. Physiol., Leipzig u. Wien, 1887, S. 700. 

* ““CEuvres de Lavoisier,” tome ii. pp. 688, 704; Hist. Acad. roy. d. sc., Paris, 1789, 
p. 575. See also Rep. Brit. Ass. Adv. Sc., London, 1871, p. 189. 

° Vierordt, ‘‘ Physiol. des Athmens,” 1845; E. Smith, Phil. Trans., London, 1859, 
vol. cxlix., p. 681; Speck, Schrift. d. Geselisch. z. Befird. d. ges. Naturw. zu Marburg, 
1871, Bd. x. ; Liebermeister, Deutsches Arch. f. klin. Med., Leipzig, 1872, Bd. x. S. 89, 
420; Lehmann, Virchow’s Archiv, 1873, Bd. lviii. S. 92. Johansson, Skandin. Arch. f. 
Physiol., Leipzig, 1897, Bd. vii. S. 123. 

8 Arch. f. d. ges. Physiol., Bonn, 1890, Bd. xlvi. S. 189. 


WARM-BLOODED ANIMALS. 413 


feels cold, is not necessarily brought about by a conscious effort of the 
will; it is to a great extent reflex, and shows itself in the more energetic 
performance of work, or, if no work be done, the reflex may become so 
imperative as to give rise to involuntary movement, shivering, which is 
only of value to the organism as a source of greatly increased heat 
production. There is little doubt but that a normal man, who feels cold 
and is free to follow the dictates of his sensations, will be more active, 
and will produce more carbon dioxide and absorb more oxygen than he 
would in warm surroundings. The man who suppresses increased 
muscular action when he feels cold, is abnormal. It follows, therefore, 
that man is no exception to the general rule that warm- -blooded animals 
in cold surroundings increase, in warm surroundings diminish, their 
respiratory exchange and production of heat. 

It has already been shown that a rise or fall in external temperature 
determines in the same direction a variation of the respiratory exchange 
of cold-blooded animals. What, then, is the cause of the totally opposite 
result observed in warm-blooded animals? To this question only an 
incomplete answer can be given. The difference is due to the nervous and 
muscular mechanisms which maintain the fairly constant temperature 
observed in the warm-blooded animals. For if, as Sanders-Ezn? and 
Pfliiger 2 have shown, the exposure to cold be excessive, and the animal’s 
temperature falls to 26°, then also there is a fall in the intake of oxygen 
and the output of carbon dioxide; on the other hand, if by means of 
warm baths the internal temperature of the animal is raised above the 
normal, then there is an increase above the average respiratory exchange. 
In fact, a warm-blooded animal responds to a rise or fall in the tempera- 
ture of its surroundings with a decrease or increase of its metabolism, 
only as long as its internal temperature remains near the normal point. 
Moreover, Pfliiger has proved the connection between the normal 
response to a change of external temperature and the nervo-muscular 
system, for he shows that a mammal paralysed with curari® or with its 
spinal cord cut in the lower cervical region, absorbs more oxygen and 
discharges more carbon dioxide in warm than in cold surroundings ; it 
resembles in this respect a cold-blooded animal. A similar cold-blooded 
condition can be produced in mammals, as Rumpf,* Richet,? and 
Pembrey® have observed, by exposing the anesthetised animal to 
changes of temperature. 

The objection that these experiments are associated with markedly 
abnormal conditions, and therefore cannot indicate the true condition of 
normal animals, is met by the fact that it is possible to trace the 
gradual development of the means whereby an animal increases or 
decreases its metabolism and maintains a fairly constant heat of its 
body, notwithstanding wide variations in the temperature of its 
surroundings. This has been shown by Pembrey” in a series of 
comparative experiments upon full-grown and newly-born animals. In 
the full-grown mouse the response to a change of external temperature 


1 Ber. d. k. stichs. Gesellsch. d. Wissensch. Math.-phys. Kl., Leipzig, 1867, S. 58. 

2 Arch. f. d. ges. Physiol., Bonn, 1878, Bd. xviii. S. 247. 

3 See also Zuntz, Arch. f. d. ges. Physiol. Bonn, 1876, Bd. xii. S. 522. 

4 Thid., 1884, Bd. xxxiti. S. 538. 

5 Compt. rend. Acad. d. s¢., Paris, 1889, tome cix. p. 190. 

& “Proc. Physiol. Soe., Journ. Physiol., Cambridge and London, 1894-95, vol. xvii. 
7 Journ. Physiol., Cambridge and London, 1894, vol. xv. p- 401; 1895, vol. xviii. 


p. 363. 


714 CHEMISTRY OF RESPIRATION. 


is almost immediate. The contrast in the case of young mice of 
different ages is shown by the fact that a fall in external tempera- 
ture produces a fall in the output of carbon dioxide, and in the 
temperature of the young mouse, until it is about nine days old, when 
it begins to respond in a similar way to that observed in a full-grown 
aninal. 

A similar development can be observed in other young animals born 
in an Immature condition, and in the chick! before and after it is 
hatched, but a marked contrast is found in young animals born with a 
well-developed and active body.? 

The influence of muscular activity upon the respiratory ex- 
change.—Muscular activity greatly increases the rate of breathing, the 
intake of oxygen, and the output of carbon dioxide. It was but natural, 
therefore, that physiologists should attribute the hyperpncea caused by 
excessive muscular exertion to a deficiency of oxygen, or to an accumula- 
tion of carbon dioxide in the blood, consequent upon the greatly increased 
metabolism. This theory, however, has been proved by experiment to. 
be erroneous. Mathieu and Urbain® determined the gases present in 
samples of blood removed from an animal after a period of rest, and 
again after a period of activity, and they found as a general result an 
increase in the oxygen, and a decrease in the carbon dioxide of the 
blood in the latter condition. Their analyses, however, were subject to 
certain sources of error. The question has been more thoroughly 
investigated by Geppert and Zuntz,t who found that muscular activity 
is indeed accompanied by an increase in the oxygen’and a decrease in 
the carbon dioxide of the blood, and that the hyperpneea is probably due to 
some product of muscular activity which is absorbed by the blood and 
carried to the medulla oblongata, where it stimulates the respiratory 
centre. The chief evidence for these statements will now be given. 
After section of the spinal cord of a dog in the dorsal region, tetanisation 
of the hind limbs causes an increase in the air inspired, in the intake of 
oxygen, and in the output of carbon dioxide. 


Dog weighing 2100 Girms. 


5 rol Oe co, 
tt ee Saar wegy as Intake of Oxygen. Output of Carbon Dioxide. ie Condition. 
| 
Per Kilo. Body Weight and per Minute. 
1012 c.c, 20°4 e.c. 18:2 ¢.c. *89 | Rest. 
| 2148 ,, 368! ,; 31:84; 86 | Tetanus. 
863 ,, PALE | LG: 7D) JRest 
1326 ,, 29° Dhs LORS “66 | Tetanus. 


1 Pembrey, Gordon, and Warren, Jowrn. Physiol., Cambridge and London, 1894-95, 
vol. xvil. p. 331. 

2 See also ‘‘ Animal Heat,” this Text-book, vol. i. p. 803. 

3 Arch. de physiol. norm. et path., Paris, 1871-72, tome iv. ; Compt. rend. Acad. d. sc., 
Paris, 1872, tome Ixxiv. p. 190. 

4 Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xlii. S. 189. 

° See also Hanriot and Richet, Compt. rend. Acad. d. sc., Paris, 1888, p. 75. 


INFLUENCE OF MUSCULAR ACTIVITY. 715 
Analyses of the gases of blood taken from an animal after voluntary 


or involuntary muscular exertion show an increase in the oxygen and a 
decrease in the carbon dioxide. 


Gases of the Arterial Blood. 


OXYGEN CARBON DIOXIDE 
VOLUMES PER CENT. VOLUMES PER CENT. 
ANIMAL. 

Rest. Activity. Rest. Activity. 

17°58 at 38°57 } 

c| Dog. 

17°33 17°68 36°49 35°01 j 

15°88 More than 16°04 53°71 39°06 Rabbit. 


\ 


Further, if the aorta be compressed in order to shut out the blood 
from the stimulated limbs, no hyperpncea is caused by the muscular 
activity; section of the vagi, sympathetic and recurrent nerves, or 
section of the cord high up, does not prevent the stimulating effect of 
muscular exertion upon the respiratory centre. In rabbits the alkalinity 
of the blood is diminished by the acid formed during tetanic muscular 
activity, and this is probably a cause of the decrease in the carbon 
dioxide of the blood. No alteration could be found in the tension of the 
oxygen and carbon dioxide present in the blood removed from an 
animal after muscular exertion.1 

Lehmann? has shown that the injection of normal solution of 
tartaric acid stimulates and quickens the respiration of a rabbit, whereas 
a normal solution of sodium hydrate depresses the respiratory centre. 
According to Lowy’s? experiments, the unknown substance which 
stimulates the respiratory centre during muscular activity is not 
excreted by the kidneys, and is not carbon dioxide ; for whereas the rate 
of respiration is doubled by muscular work when the increase above the 
normal amount of carbon dioxide in the expired air is only 0°5 per cent., 
yet the same amount of dyspnoea can be produced during rest only by 
artificially raising the percentage of carbon dioxide to a much higher 
point, about 5 per cent. 

The credit of the discovery that work is associated with an increase 
in the respiratory exchange, is due to Lavoisier,! who, in a series of 
experiments with Seguin, found that a man at work absorbed 91:2 
grms. of oxygen in an hour, whereas at rest he only absorbed 38:3 
grms. Although Vierordt® and Scharling® both observed a similar 
increase in the output of carbon dioxide in men at work, the first 
series of careful experiments on the subject were those performed by 

1 For criticism see Speck, Deutsches Arch. f. klin. Med., Leipzig, 1891, Bd. xlvii. S. 509 ; 
for reply by Zuntz and Geppert, ibid., 1891, Bd. xlviii. S. 444. 

2 Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xlii. S. 284. 

8 Thid., S. 281; 1890, Bd. xlvii. S. 601. 
col Hist. Acad. roy. d. sc., Paris, 1789, p. 185 ; ‘* uvres de Lavoisier,” tome ii. pp. 688- 
5 « Physiol. des Athmens,” Karlsruhe, 1845; Arch. f. physiol. Heilk., Stuttgart, 
Bd. iii. S. 536 ; Wagner’s ‘‘ Handworterbuch d. Physiol.,’’ 1844, Bd. ii. S. 828. 


§ Ann. d. Chem. u. Pharm., 1843, Bd. xlv. S. 214; Journ. f. prakt. Chem., Leipzig, 
Bd. xlyiii. S. 435. 


716 CHEMISTRY OF RESPIRATION. 


KE. Smith.t He found that a man produced 161°6 e.c. of carbon dioxide per 
minute when he was perfectly at rest, as in a deep sleep; that during a 
walk at the rate of two miles (3048 metres) an hour, the discharge of 
carbon dioxide was increased to 569°5 «c., and to 851-2 ec. when the 
rate of walking was quickened to three miles (4571-9 metres) an hour. 
The greatest increase, 1581-9 ¢.c. of carbon dioxide per minute, was 
caused by work upon a treadmill. 

In 1866, Pettenkofer and Voit? performed a series of important 
observations upon the metabolism of healthy men, under different con- 
ditions as regards work and diet, and they found that if unity represent 
the value of the output of carbon dioxide and the intake of oxygen 
when the man is at rest, then work brings about the following 
results :— 


During Hunger, Moderate Diet. 
Carbon dioxide : : 2°3 A 
Oxygen . : : ‘ 2°1 18 


The numerous experiments made by Speck,? under different con- 
ditions as regards the amount and nature of the work performed, show 
that the air inspired, the oxygen absorbed, and the carbon dioxide 
discharged, are greatly increased; the percentage composition of the 
expired air is but little altered, and the respiratory quotient increases 
slightly during the work. Hanriot and Richet* find for each kilo- 
grammetre of work performed by a man, an increase of 37168 e.c. in the 
oxygen absorbed, and 4221 cc. in the carbon dioxide discharged. 

In experiments upon horses, Zuntz and Lehmann® obtained the 
following results :— 


LITRES PER MINUTE. 
co, 
Me, O.. 
Air expired. Teas Oxygen absorbed. 
Rest 44 1°478 1°601 92 
Walk iis 4342 4°766 “90 
Trot 335 7°516 8093 93 


It is impossible here to discuss fully the quantitative relationship 
between metabolism and work, but the conclusions reached by Katzen- 
stein ® are as follows:—The work performed by the arms in turning a 
wheel produces, per unit of work done, a greater increase in the respiratory 
exchange than walking or climbing; the absorption of oxygen is per unit 
of work performed somewhat greater for light, than for heavy work ; 
the absorption of oxygen and the discharge of carbon dioxide increase 


' Phil. Trans., London, 1859, vol. exlix. pt. 2, p. 681. 

* Ztschr. f. Biol., Miinchen, 1866, Bd. ii. S. 459. See also this article, p. 718, and 
article by Voit in Hermann’s ‘‘ Handbuch,” Bd. vi. Th. 1, S. 201. 

* Deutsches Arch. f. klin. Med., Leipzig, 1889, Bd. xlv. S. 461. 

4 Compt. rend. Acad. d. sc., Paris, 1887, tome civ. p. 1865; tome cv. p. 76. 

> Landw. Jahrb., 1889, Bd. xviii. S. 1; Journ. Physiol., Cambridge and London, 1890, 
vol. xi. p. 396. 

5 Arch. f. d. ges. Physiol., Bonn, 1891, Bd. xlix. S. 380. 


INFLUENCE OF FOOD. 717 


equally under ordinary conditions, so that the respiratory quotient 
remains practically unaltered. It is only immediately after work that 
the respiratory quotient increases, and becomes sometimes greater than 
unity. The absorption of oxygen needed for the work of walking on 
level ground is, per kilo. body weight and minute, 01682 ce. 
maximum, and 0:0858 ¢c.c. minimum; for each kilogrammetre of work 
performed in climbing, 1:5036 ¢.c. maximum, and 11871 minimum; and 
similarly, for turning the wheel, 1°957 c.c. 

Léwy ! shows that there is no definite value which can be assigned to 
the increase of the respiratory exchange for the performance of a given 
quantity of work under all circumstances, for the metabolism depends 
upon the activity of the muscle, which varies under different conditions. 
Active muscle working under fayourable conditions performs its work 
economically ; fatigued muscle working under unfavourable conditions 
is the seat of an extravagant metabolism.” 

The decrease observed in the respiratory exchange of animals under 
the influence of chloroform, ether, chloral, and curari, is to be attributed 
chiefly to the great decrease in the activity of the muscles.* 

The influence of food upon the respiratory exchange.—The effect 
of a meal upon the respiratory exchange is to cause a marked increase 
in the intake of oxygen and the output of carbon dioxide; this is due 


Me: ioxi ge F 
a ere Condition of Animal 
Grms. C.c. 
7 1°423 723 Pregnant ; very liberal diet of meat. 
52 | 0-902 458 The same animal ; hunger for18 dys. 
4 | 0-998 507 é i. Thess 
4 0°732 372 > ” 
shortly before death. 
6 0°847 430. Male, kept at constant weight with 
diet of meat. 
2 1°364 693 Male, maximal diet of meat. 
23 0°888 451 Male, normal diet of meat, but 
without water. 
12 0°679 345 Male, inanition, but with water 
supplied. 
i 1°702 865 Female, not full grown; diet of 
meat. 
6 1500 763 Female, diet of fat. 


1 Arch. f. d. ges. Physiol., Bonn, 1891, Bd. xlix. S. 405. See also, Gruber, Ztschr. f. 
Biol., Miinchen, 1891, Bd. xxviii. 8. 466. 

* For further experiments upon the influence of work upon the respiratory exchange of 
(a) man, see Hanriot and Richet, Ann. d. chim. et phys., Paris, 1891, Sér. 6, tome 
xxii. p. 495; and Trav. du lab. de Ch. Richet, 1894, tome 1; (5) animals, Grandis, Arch. 
ital. de biol., Turin, 1889, tome xii. p. 237; Smith, Journ. Physiol., Cambridge and 
London, 1890, vol. xi. p. 65. Criticism of the same by Zuntz and Lehmann, ibid., p. 396 ; 
Gréhant, Compt. rend. Soc. de biol., Paris, 1891, p. 14. 

3 Zuntz, Arch. f. d. ges. Physiol., Bonn, 1876, Bd. xii. S. 522; Pfliiger, zbid., 1878, 
Bd. xviii. S. 247; Rumpf, ibid., 1884, Bd. xxxiii. S. 538; Saint Martin, Compt. rend. 
Acad, d. sc., Paris, 1887, tome cy. p. 1126; Richet, ibid., 1889, tome cix. p. 190; Arch. 
de physiol. norm. et path., Paris, 1890, tome ii. p. 221; Pembrey, ‘‘ Proc. Physiol. Soc.,” 
Journ. Physiol., Cambridge and London, 1894-95, vol. xvii. 


718 CHEMISTRY OF RESPIRATION. 


not only to the chemical changes which take place in the food during 
digestion and absorption, but also to the increased glandular and 
muscular activity of the alimentary canal.? 

Although Lavoisier? knew that food greatly increased the respiratory 
exchange, the first experiments of importance in this connection are those 
of Bidder and Schmuidt,? who made numerous observations upon cats; 
the results of some of their experiments are given in the preceding table. 

In the case of man and other animals, the influence of food of 
various kinds, and of fasting, has been studied by Pettenkofer and 
Voit,t Senator,> Henneberg® Leyden and Frankel,’ Fredericq and 
others ;® the general result is that a meal causes an increase in the 
intake of oxygen and the output of carbon dioxide, whereas a day of 
fasting causes a decrease. The average results obtained upon man by 
Pettenkofer and Voit !° are as follows :— 


nine hours out of twelve 


CARBON DIOXIDE. OxyGeEn,11 

| Day. | Night. Day. Night. 

| | 
Grms. Grms. Grms. Grms. 
1. Fasting—Rest 403 314 435 326 
ap Work for nine 930 257 922 150 

hours out of twelve 
2, Moderate Diet—Rest | 533 395 443 | 449 
i. ,, Work for | 856 353 795 | 211 


Upon the fasting-man Cetti, determinations of the respiratory 
exchange were made by Zuntz and Lehmann,” and they found that the 
absorption of oxygen and the discharge of carbon dioxide per kilo. 
of the man’s weight quickly reached its minimum, and did not fall 
below this point during the progress of the fast; in fact there was a 
slight increase. Thus the absorption of oxygen per kilo. and minute 
was 4°65 cc. on the third to sixth day, and 4°73 cc. on the ninth to 
eleventh day of the fast. Before the first meal at the end of the 


1 See p. 719. 

2 << (Ruvres,” tome ii. pp. 695-696. 

3 « Die Verdauungssafte und der Stoffwechsel,” Leipzig, 1852, S. 321-362. 

4 Ann. d. Chem. u. Pharm., 1862-63, Supp. Bd. ii. 8. 52-361. 

5 Arch. f. Anat., Physiol., u. wissensch. Med., 1872, 8. 1. 

6 Landwirthsch. Versuchsstat., 1869, S. 306, 409. 

7 Virchow’s Archiv, 1879, Bd. lxxvi. S. 136. 

8 Arch. de biol., Gand, 1882, tome iil. p. 733. 

2. Smith, Phil. Trans., London, 1859, vol. exlix. p. 715; Hanriot and Richet, 
Compt. rend. Acad. d. sc., Paris, 1888, tome cvi. p. 419; Zuntz, Fortschr. d. Med., Berlin, 
1887, Bd. v. S. 1; Meissel, Strohmer, and Lorenz, Zéschr. f. Biol., Miinchen, 1886, Bd. 
xxii. S. 63; Boeck and Bauer, ibid., 1874, Bd. x. S. 336; Geppert, Arch. f. exper. Path. 
u. Pharmakol., Leipzig, 1887, Bd. xxii. S. 366; Hanriot and Richet, Ann. de chim. et 
phys., Paris, 1891, Sér. 6, tome xxii. p. 495; Marcet, Proc. Roy. Soc. London, 1892, 
vol. 1. p. 58; 1893, vol. lii. p. 213; Rubner, Beitr. 2. Physiol. Carl Ludwig z. s. 70 
Geburtst., Leipzig, 1887, S. 259 ; Johansson, Landergren, Sonden, and Tigerstedt, Skandin. 
Arch. f. Physiol., Leipzig, 1896, Bd. vii. S. 29. 

0 Ztschr. f. Biol., Munchen, 1866, Bd. ii. S. 459. 

11 For criticism of the determination of oxygen, see p. 696. 

12 Berl. klin. Wehnschr., 1887, 8. 428. 


ACTIVITY OF THE ALIMENTARY CANAL. 719 


fast the absorption of oxygen and the discharge of carbon dioxide were 
4:67 cc. and 3:16 cc. per kilo. and minute; after this meal the 
figures were respectively 5-05 c.c. and 3°46 cc. The effects of the fast 
and of food upon the respiratory quotient were as follows :— 


; : Co, 
On last day of food, mixed diet ; a ae = 0-73 
On second day of fasting . ; : ore OS 
On third day of fasting : : Pile ‘a O65 
During the remainder of the fast ; ae 5  0°66-0°68 
When food, mixed diet, was again taken . __,, oo O-13=-O8! 


Regarding the influence of diet upon the respiratory quotient, it is 
only necessary here to state that an animal fed on a vegetable diet has a 
quotient closely approaching unity, for its chief food, the carbohydrates, 
contains enough oxygen to combine with the hydrogen to form water ; 
that a carnivorous animal has a quotient about 0°74, and an omnivorous 
animal, such as man,a somewhat higher quotient!; and finally, that 
even a herbivorous animal has a low quotient during starvation, for it 
then lives upon its own tissues. 

The influence of activity of the alimentary canal upon the 
respiratory exchange. —It has already been shown that a meal 
increases the respiratory exchange, and this effect was originally attri- 
buted solely to the oxidation of the food material taken up by the 
blood. Speck,? however, in 1874, pointed out that this increase in 
metabolism followed the taking of food so rapidly that it appeared to be 
due, in the first place, to the augmented activity of the alimentary canal. 
The first experiments to support this view were those made by Mering 
and Zuntz, who showed that food placed in the stomach increased the 
absorption of oxygen and the discharge of carbon dioxide, whereas sub- 
stances such as lactic acid, butyric acid, glycerin, sugar, egg albumin, and 
peptone, injected into the blood, increased the output of carbon dioxide, but 
had no marked effect upon the intake of oxygen. Rubner* and Fredericq?® 
also found increased metabolism after food, due apparently, in the first 
place, to the activity of the glands of the alimentary canal;* and the 
observations made by Lehmann and Zuntz* upon the fasting-man 
Cetti showed that during the fast the respiratory exchange was 
constant, except on two days when Cetti suffered from colic; there 
was then an increase in the intake of oxygen and the output of carbon 
dioxide. These pieces of evidence have been followed up by Lowy,s 
who determined the respiratory exchange of fasting men before and 
after the activity of the alimentary canal had been increased by a dose 
of sodium sulphate, or a draught of cold water. Experiments made 
upon six men showed that the increased activity of the alimentary canal 
brought about in this way increased the intake of oxygen and the 
output of carbon dioxide by about 10 per cent.; the greatest increase 


1 See tables on pp. 706-708. 

2 Arch. f. exper. Path. u. Pharm., Leipzig, 1874, Bd. ii. 

3 Arch. f. d. ges. Physiol., Bonn, 1877, Bd. xv. S. 634; 1883, Bd. xxxu. 8. 173, 

4 Ztschr. f. Biol., Miinchen, 1883, Bd. xix. S. 330. 

5 Arch. de biol., Gand, 1882, tome iv. p. 433. 

6 See also Slosse, Arch. f. Physiol., Leipzig, 1890, Suppl. Bd. S. 164; Tangl, zid., 
1894, S. 283. 

7 Berl. klin. Wehnschr., 1887, S. 428. 

8 Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xliii. S. 515. 


720 CHEMISTRY OF RESPIRATION. 


was about 24 per cent. in the carbon dioxide, and 17 per cent. in the 
oxygen. Sodium chloride and sodium bicarbonate had no effect on the 
intestines or upon the respiratory exchange. Lowy suggests that the 
therapeutic value of the waters at Carlsbad and Marienbad, in cases of 
disordered metabolism, may be partly due to this stimulating effect of 
sodium sulphate. 

The influence of the size of the animal upon the respiratory 
exchange.!—The smaller an animal the greater is its surface in relation 
to its mass, for the surface increases as the square, the mass as the cube. 
Now, small mammals and birds have a temperature equal to or even 
higher than that of large animals of the same classes ; and, on account of 
the relatively greater surface which they expose for the loss of heat, 
they must have a relatively far greater production of heat than the 
large animals, for there is generally no marked difference in the pro- 
tective coat of fur or feathers. Heat is produced by a process of 
combustion in the tissues, and the respiratory exchange is a measure, 
although it may not be an absolutely exact one, of this combustion. 
Theoretically, therefore, a much more vigorous respiratory exchange 
should exist in the smaller warm-blooded animals. The experiments of 
many observers, especially of Letellier,? Regnault and Reiset,? Pott,* and 
Richet,® have shown that such is the case, not only for animals of the 
same species, living upon similar diet and having similar habits, but 
also for animals of different species, with very different diets and 
habits.® 

Paul Bert? has shown that this difference in the rate of metabolism 
in small and large animals has become habitual, for it persists even 
When the animals are put under abnormal conditions of such a kind 
that the loss of heat is relatively the same; in such an experiment a 
pigeon absorbed 234 c.c. of oxygen per 100 grms. of its body weight, and 
a sparrow 467 c.c. of oxygen. 

A series of experiments have been made by Richet § upon thirty-eight 
dogs of different sizes, their weights ranging from 22 to 28 kilos., and 
the results show that the output of carbon dioxide bears a very constant 
relation to the surface of the body, 0°0027 grms. per hour for each 
square centimetre of surface. A similar relation holds good for the 
intake of oxygen, the respiratory quotient being 0°748. This difference 
in metabolism is controlled by the nervous system, for it was found, 
in eighteen dogs of different sizes, aneesthetised with chloral, that the re- 
spiratory exchange was proportional to the weight of the body, 0°640 to 
0-694 grms. CO, per kilo. and hour. A somewhat similar series of 
observations, made upon birds® of different sizes and species, gave 
similar results. 


1 For a discussion of this subject, see paper by Hoesslin, Arch. f. Physiol., Leipzig, 
1888, S. 323, where numerous references are given; Rubner, Zéschr. 7. Biol., Miinchen, 
1883, Bd. xix. S. 535. 

2 Ann. de chim. et phys., Paris, 1845, Sér. 3, tome xiii. p. 478. 

3 Ibid., Paris, 1849, Sér. 3, tome xxvi. p. 299. 

4 Landwirthsch. Versuchsstat., Bd. xviii. S. 81. 

5 Arch. de physiol. norm. et path., Paris, 1890, tome xxii. pp. 17, 490; 1891, tome 
Xxili. p. 74. 

8 See tables, pp. 706-708. 

7 «‘Tecons sur la physiol. comp. de la respiration,” Paris, 1870, p. 503. 

8 Compt. rend. Acad. d. sc., Paris, 1889, tome cix. p. 190; Arch. de physiol. norm. et 
path., Paris, 1890, tome xxii. p. 17. 

9 Arch. de physiol. norm. et path., Paris, 1890, tome xxii. p. 490. 


INFLUENCE OF TIME OF DAY. 72t 


The influence of time of day upon the respiratory exchange.— 
During a series of experiments performed in the years 1815 and 1814, 
Prout! discovered that the amount of carbon dioxide discharged from 
the lungs appeared to be influenced by the time of day, for there was a 
regular daily variation; the maximum was generally between 11 A.M. 
and 1 p.M.; then there was a fall to the minimum at 8 P.M. or 9 P.M. in 
the evening, and at this low level the discharge of carbon dioxide 
remained until 3 A.M. or 4 A.M., when there was a marked rise. A 
similar variation was observed by Vierordt,* both in the discharge of 
earbon dioxide and in the amount of air respired, and the cause of the 
rise he attributed to food. The table on p. 722 gives his average results. 

Speck * determined the daily variation, both in the intake of oxygen 
and in the output of carbon dioxide, and showed the influence of food in 
producing the maximum. 

Further experiments upon the daily variation in the respiratory 
exchange have been made by Berg* and Fredericq.? The following 
curve represents the daily variation observed by Fredericq in the oxygen 
absorbed by a man :— 


A.M. POM. 


a ean 


LILCS8 OF OxYGEr 


Fic. 67.—Fredericq’s curve of daily variation in the absorption of oxygen. 
R = time of a meal. 


The causes of these variations in the daily respiratory exchange are 
to be attributed mainly to food and muscular activity, for during ‘sleep, 
as E. Smith Pettenkofer and V oit,’ and others® have shown, the meta- 
bolism is oreatly diminished, and also in a less degree during hunger. 
In addition, however, there appears to be a certain periodicity stamped 


1 Ann. Phil., London, 1813, vol. ii. p. 330; vol. iv. p. 331. 
4 A Physiol. ‘d. Athmens, ” Karlsruhe, 1845 ; Wagner’s ‘‘ Handworterbuch,” Bd. ii 

3 “<Untersuch. ueber Sauerstoffserbrauch wu. Kohlensiiureausathmung des Menschen,” 
Cassel, 1871, S. 31; Arch. f. exper. Path. u. Pharmakol., Leipzig, 1874, Bd. ii. S. 405 ; 
ibid., 1880, Bd. xii. S. 1. 

2  Binfluss der Athembewegungen auf die Ausscheidung der Kohlensaure durch die 
Lungen,” Dorpat, 1869. 

Arch. de biol., Gand, 1882, tome iii. p. 729. 

6 Phil. Trans., London, 1859, vol..cxlix. p. 681. 

« Zischr. f. Biol., Miinchen, 1866, Bd. ti. S. 459. 

8 Saint-Martin, Compt. rend. Acad. d. sc., Paris, 1887, tome cv. p. 1124; Rubner, 
Beitr. z. Physiol. Ca arl Ludwig z. s. 70 Geburtst., , Leipzig, 1887, S. 259. 


VOL. I.—46 


722 CHEMISTRY OF RESPIRATION. 


Volume of an | Air expired in | CO, expired in 
ronan Respirations Expiration. One Minute. One Minute. Bro eee 
per Minute. | sxpired Air. 
C.c. (37° and 758 Mm.). 
9 A.M 12°1 503 6090 264 4°32 
LO aes 1s9, 29 6295 282 4°47 
Ap - 11°4 534 6155 278 4°51 
12 noon . c nal 496 5578 243 4°36 
Dinner. 

fe ERLE ry | 12°4 513 6343 276 4°35 
Pen cg pee 516 6799 291 4:27 
[ar oees ye : 12°3 516 6377 279 4°37 
Av ys We, ‘ 12-2 517 6179 265 4°21 
Dare as ; INP yy 521 6096 252 4°13 
Gaye It GOTT 11°6 496 5789 238 4°12 
(fees ibei 489 5428 229 4°22 


upon the organism by long-continued habit—a day of work, a night of 
rest. This explains the persistence of the daily variation in metabolism, 
temperature, pulse, and respiration observed in an animal kept at rest 
and without food. 

The effect of light in increasing the respiratory exchange is pro- 
bably to be attributed chiefly to the increased muscular activity of most 
animals in the ght." 

The influence of age upon the respiratory exchange. — The 
respiration of the foetus is relatively small, and this condition, within 
certain limits, persists for a short time after birth. The estimation, 
however, of the effect of age upon the respiratory exchange is not so 
simple as it at first appears, for there are two factors which have to 
be taken into account. In the first place, the young animal has a 
relatively greater surface in proportion to its mass than the aduit 
aninal, ‘and this causes a more rapid respiratory exchange; in the 
second place, young animals of different species are born in different 
degrees of dev elopment. A newly-born guinea-pig is covered with fur, 
has its eyes open, and is able to run about and feed; whereas a newly- 
born rabbit, rat, or mouse is naked, blind, and helpless. A similar 
contrast is observed in the condition of the newly-hatched chick and 
pigeon. Elsewhere it has been shown that newly-born mammals and 
birds can be arranged in two classes—those which can and those which 
cannot maintain their temperature; and there is a similar contrast in 
the effect of changes of external temperature upon their respiratory 
exchange. These factors must, therefore, be remembered in estimating 
the effect of age upon the respiratory exchange. 

In the case of man, experiments have been made by Andral and 
Gavarret,? but it is difficult to estimate the influence of the ratio 
between mass and surface of the body, for the weights of the subjects 
are not given. In the following table are some of Scharling’s ? results, 
which show that, weight for weight of body, the child discharges more 
carbon dioxide than the adult :— 


1 Numerous references to the controversy on this point will be found in a paper by 
Fubini and Benedicenti, Arch. itaZ. de biol., Turin, 1891, vol. xvi. p. 80. 
“ Recherches sur la quantité d’acide car bonique exhalé par le poumon dans T’espéce 
hemaiie ” Paris, 1843. Extract in Ann. de chim. et phys., Paris, 1843, Sér. 3, tome viil. 
3 Ann. d. Chem. u. Pharm., 1843, Bd. xly. S. 214. 


RESPIRATION BY THE SKIN. 723 


| 
Output of Output of 
Sex. Age. Weight. Carbon Dioxide in Carbon Dioxide | 
: Twenty-four Hours. per Kilo. and Hour. 
Kilo. Grms. Grms. | 
feNalewer : 35 years | 65°5 804°72 0°512 | 
ee iD} Dears lows 82 878°95 0497 
- eae ae Parma Oe Bar 822°69 0-594 
|Female. 194," liped SB-75' Pes) 608 °22 0°455 
| 
iene —— 93 ,, 22 | 488°14 0925 
Female . c WD 52 23 459 °87 0°833 


A series of experiments by Pembrey! has shown that the effect of 
age upon the respiratory exchange must be considered in relation to the 
temperature of the external air and the stage of development in which 
the animal is at birth. Animals born in a condition of advanced 
development, like that of guinea-pigs and chickens, have a respiratory 
exchange which is relatively two or three times greater than that of 
the adult. Animals born in a helpless state, like that of mice and 
pigeons, have at the ordinary temperature of the air a metabolism 
relatively smaller than that of the adult; but with a rise in the 
external temperature towards the temperature of the body the re- 
spiratory exchange increases towards the value in the adult. These 
differences, which are intimately connected with the temperature of 
the animal, are discussed more fully in other parts? of this work. 


RESPIRATION BY THE SKIN AND ALIMENTARY CANAL. 


Cutaneous respiration of amphibia.—In many of the lower animals 
the exchange of gases between the skin and the surrounding air or water is 
considerable, and in some of the amphibia is equal to, or even greater than, that 
effected by the lungs. As early as the end of the last century, Spallanzani # 
showed that many amphibia could readily take up oxygen and discharge 
carbon dioxide after their lungs had been nce and that in this condition 
they lived longer than animals of the same species whose skin had oaEe 
covered with varnish. These observations were extended by Edwards,‘ 
who found that frogs deprived of their lungs would live a long time, eroded 
that the external temperature was low. This cutaneous respiration took place 
as readily in flowing water as in air, for normal frogs could be kept alive 
although never allowed to come to the surface, provided that the temperature 
of the water did not exceed 12°; the cutaneous respiration was sufficient for 
the small amount of metabolism which occurred at low temperatures. Regnault 
and Reiset® found, by direct experiment, that frogs absorbed as much oxygen 
and discharged as much carbon dioxide after, as before, removal of their 
lungs. The following figures give their results :— 


1 Journ. Physiol., Cambridge and London, 1895, vol. xviii. p. 363. 
2 See ‘* Animal Heat,” this Text-book, vol. i. 
3 «* Mémoires sur la respiration, ” trad. par Senebier, Genéyve, 1803, pp. 72, 114. 
+ “De l’influence des agens physiques sur la vie,’ ’ Paris, 1824, pp. 12, 41-62. 
° Ann. de chim. et phys. , Paris, 1849, Sér. 3, tome xxvi. p- 506. 


724 CHEMISTRY OF RESPIRATION. 


patel Carbon Dioxide 
Condition of Frog. ae ee aed Pe —_ = Temperature. Remarks. 
g and Hour. 2 
| 
Grms. Grms. pre 

{ Min. 0°063 0°045 69 | 15°-9° |) Result of 
Normal . = 5 | five experi- 

| Max. 0°105 0-081 oe | 3 ments. 

5 = : ee | bo 
After removal of | 0°04; es ie | My 

ina | 0-066 0-071 79 | 21° 


Berg,! on the other hand, found the discharge of carbon dioxide considerably 
diminished, but this has not been confirmed by Fubini,? who observed, in 
comparative experiments, only a slight decrease in the output of carbon 
dioxide after removal of the lungs. 

To all of these experiments there are certain objections. The varnish, 
especially when containing alcohol, acts injuriously on the frog, and interferes 
with its free movement ; the removal of the lungs, apart from the actual injury 
done to the animal during the operation, may cause the skin to take on 
vicariously the function of respiration. Later experiments by Klug® are free 
from these objections, for the head of a normal frog was passed through a 
rubber collar into one part of a chamber, while the body was retained in the 
other part—the pulmonary and cutaneous respiration were thus determined 
separately ; and in order to allow for the cutaneous respiration which would 
take place on the head, other experiments were made, in which only the nose 
projected, and in which section of the vagi nerves, an operation which suspends 
the pulmonary respiration, had been performed. The results show that, during 
the winter at least, the cutaneous respiration is far more important than the 
pulmonary. 


3 
= I.—COz per | II.—COz per | 
z roma Weight | 100 Grms. and | 100 Grms. and Ratio | 
Ta peers of Sex. 24 Hours. 24 Hours. of Remarks. 
a none Frog. | Head and Body below I. to Il. 
g 5 Lungs. Head. | 
Hours.} Grms. Gris. Gris. 
1 3 il Male | ‘0581 | 1891 1-3°2 Normal. 
3 5 111 a5 “0540 "1902 1-35 | a5 
‘8 s 82 Female 0536 2361 1-4°4 | Only the nose pro- 
| jected through the 
partition. 
9 - Difial ft 0175 ‘0786 1-474 Both — vagi eut : 
: | membrane as in 
Experiment 8. 


Dissard + has determined the production of carbo dioxide after ligature of 
the cutaneous or the pulmonary blood vessels of frogs, and he finds that both 
cutaneous and pulmonary respiration are necessary to the animal, for the 


1 «¢Untersuch. ueber d. Hantathmung d. Frosches,” Diss., Dorpat, 1868. 
2 Untersuch. z. Naturl. d. Mensch. u. d. Thiere, 1878, Bd. xii. S. 100. 

3 Arch. f. Physiol., Leipzig, 1884, 8. 183. 

4+ Compt. rend. Acad. d. sc., Paris, 1893, tome exvi. p. 1153. 


CUTANEOUS RESPIRATION OF MAMMALS. 725 


removal of either causes death after a longer or shorter period. The cutaneous 
respiration appears to be the more important during the winter, and the 
pulmonary during the summer. The experiments of Marcacci! indicate that 
the mucous membrane of the mouth and pharynx is also respiratory in the 
frog, and Camerano? finds in the case of the salamanders Spelepes fuscus 
and Salamandrina perspicillata, in which the lungs are either absent or 
rudimentary, that the bucco-pharyngeal respiration is more important than 
that carried on by the skin. 

Valentin® determined the absorption of oxygen and the discharge of 
carbon dioxide from pieces of skin removed from the body of the frog, and 
found that the former process was the more active. This has been confirmed 
by Waymouth Reid and Hambly,? who, from experiments upon the’ transpira- 
tion through the frog’s skin, conclude that there is no evidence of any 
physiological action by virtue of which carbon dioxide is “secreted”; the 
exchange of gases is the direct result of a difference of tension on the two sides 
of the respiratory septum. 


Cutaneous respiration of mammals.—In man and other mammals 
the cutaneous respiration is so small that it has been denied by some 
observers,> and explained away by others, as arising from the decom- 
position of filth and cutaneous secretions.® Although Hippocrates and 
Galen believed in the absorption of air by the skin, no experiments 
appear to have been made until the year TTT when Milly observed, 
during a warm bath, a number of smal] bubbles attached to the surface 
of his body ; some of these bubbles were collected, and on analysis were 
found by Lavoisier? to be carbon dioxide. Objection was raised to this 
experiment, on the ground that carbon dioxide present in the water 
might attach itself to the body, as it does to other solid substances. 
Cruikshank S however, found that air, in which a previously washed 
hand or foot had been confined for one ‘hour, caused a marked turbidity 
with lime water. These experiments were extended by Abernethy,° 
who showed that in ordinary air oxygen was absorbed and carbon 
dioxide was given off as readily as in pure oxygen, whereas in carbon 
dioxide gas nitrogen was discharged and carbon dioxide absorbed by the 
skin of the hand. 

In Lavoisier and Seguin’s? experiments a man was enclosed in an 
air-tight rubber bag, while he breathed through two tubes connected 
with the mouth and nose; this method was improved by Scharling," 
who prevented the excessive accumulation of moisture by ventilating 
the chamber in which the subject of the experiment was confined. 
The results of the above and later observers are given in the following 
table :-— 


1 Arch. ital. de biol., Turin, vol. xxi. p. 1. 

2 [bid., vol. xxi. p. 387. 

3 Arch. f. physiol. Heilk., Stuttgart, 1855, S. 474. 

4 Journ. Physiol., Cambridge and London, 1895, vol. xvili. p. 411. 

5 Priestley, ‘‘On “Air,” vol. ii. pp. 193, 194 ; Klapp and Gordon, ‘‘ Ellis’s Inquiry ”’ 
Edinburgh, 1807, pp: 189, 354. 

6 Hoppe-Seyler, * ‘Physiol. Chem.,” Berlin, 1879, Bd. iii. S. 580. 

7 Hist. Acad. roy. d. sc., Paris, 1777, pp: 221, 360. 

8“ Rxperiments on the Insensible Perspiration of the Human -Body, showing its 
affinity to Respiration,” 2nd edition, London, 1795, pp. 81, oo 

» «*Surgical and Physiological Essays, ’ London, 1793, pt. 2 2, p- 107. 

1 « (uvres de Lavoisier,” Paris, 1862, tome ii. p- 708; Ann. de chim. et phys., 
Paris, 1814, tome xe. p. 8. 

1 Journ. f. prakt. Chem., Leipzig, 1845, Bd. xxxvi. S. 454; Ann. de chim. et phys., 
Paris, 1843, Sér. 3, tome vill. p. 480. 


726 


CHEMISTRY OF RESPIRATION. 


Part of Body 


Gases Discharged. 


Gases Absorbed. 


CO, 
Discharged. 


| oO, 
Absorbed. 


Observer. 


Total surface of 
skin of man 

Total surface of 
skin of child, 
eet. 10 

Total surface of 
skin of girl 
et. 19 


Portion of skin 
of man 
Arm of man 


99 
Total surface of 
skin of man, 
except head 


9? 


Hand : 

Hand and fore- 
arm 

Upper limb of 
man 

Portion of skin 
of a horse 

Total skin of a 
horse 


Carbon dioxide 


Carbon dioxide 


+) 99 


Oxygen 


| Not determined 


PP} 99 


29 22 


Oxygen 


Examined: For Total Surface of Body 
in 24 hours. 
Hand and foot | Carbon dioxide} Not determined Cruikshank.? 
of man 
Hand of man |Carbondioxide, | Oxygen 14 grms. Abernethy.” 
and  some- 
times nitro- 
gen 
Total surface of 5 Lavoisier and 
skin of man Seguin.® 
Portions of skin | Carbon dioxide | Not determined Collard de Mar- 
of man and nitrogen tigny.* 


32°8 grms. 


10°9 grms. 


23°9 grms. 


8-4 orms, | 2°7 grms. 
2°2 grms. ay 

14 grms. a 
6°3 grms. 39 
(maximum) 

2°3 grms. 3 
(minimum) 

1°25 grms. is 
6°80 grms. 3 


0193 grm.??) 


30°1 grms. | 6°3 grms. 


119 grms. 55 


Scharling.*® 


Regnault and 
Reiset.® 
Gerlach.7 


Reinhard.® 

Rohrig.? 

Aubert and 
Lange. 


39 a 


39 39 
Fubini and 
Ronchi.!! 

Barratt.!8 


Gerlach.7 
Zuntz,  Leh- 


mann, and 
Hagemann.!4 


The results of Aubert which have been given above show that the 
cutaneous respiration varies in intensity in different parts of the body, 
and that for this reason it is impossible to correctly calculate the 
cutaneous respiration of the whole body from the data obtained on one 


limited part, such as the hand. 


1 Loc. cit. 


3“ (Ruvres de Lavoisier,’ 


’ 


1814, tome xe. p. 8. 
4 Journ. de physiol. expér., Paris, 1830, tome x. p. 162. 
> Journ. f. prakt. Chem., Leipzig, 1845, Bd. xxxvi. S. 454, Ann. de chim. et phys., 

Paris, 1843, Sér. 3, tome viii. p. 480. 
6 «* Recherches sur la respiration des animaux,” p. 209. 

7 Arch. f. Anat., Physiol. w. wissensch. Med., 1851, S. 431. 

8 Ztschr. f. Biol., Miinchen, 1869, Bd. v. S. 28. 

9 Deutsche Klinik, Berlin, 1872, Bd. xxiv. S. 209, 225, 234. 

” Arch. f. d. ges. Physiol., Bonn, 1872, Bd. vi. S. 539. 

1 OUntersuch. z. Naturl. d. Mensch. wu. d. Thiere, 1881, Bd. xii. S. 1. 
2 For upper limb alone and for one hour; temperature of air=35°. 
8 Journ. Physiol., Cambridge and London, 1897, vol. xxi. p, 204. 
M4 Arch. f. Physiol., Leipzig, 1894, S. 351. 


2 Loc. Cit. 


Paris, 1862, tome ii. p. 


708 ; 


Further, the exchange of gases from the 


Ann. de chim., Paris, 


EFFECTS OF VARNISHING THE SKIN. 727 


skin is increased by exercise, a rise of temperature, and by any cause 
which produces increased vascularity of the skin, such as friction, warm 
baths, and electric shocks! It is also said to be influenced by food 
and by exposure to light.” 

The experiments of Gerlach, Rohrig, and others show that the skin 
of animals will absorb carbon dioxide, carbon monoxide, sulphuretted 
hydrogen, and the vapour of chloroform and ether. 

The effects of varnishing the skin.—The old theory, held by Galen, 
Sanctorius, and others, that many diseases were due to the retention of 
waste substances which in a normal condition would have been dis- 
charged from the body, received great support from experiments in 
which the skin of animals had been covered by an impermeable layer 
of varnish or ointment. At the same time it was held that the results 
showed the imperative necessity of cutaneous respiration and perspira- 
tion. The symptoms observed after the skin of an animal was varnished 
were restlessness, shivering, increased rapidity of breathing and heart- 
beat, soon followed by‘slow respiration and pulse, a fallin temperature 
to 20° or 19°, the discharge of albumin in the urine, spasms, and death. 

_ Examination of the body after death showed congestion of the skin, 
subcutaneous tissue, muscles, and internal organs.? 

The earliest experiments appear to have been made by Fourcault,* 
Ducros,’ Becquerel and Brechet,® Gluge,” and Magendie.? The tempera- 
ture was observed by Gerlach,® who obtained the following results for 
a rabbit and a horse, after their skins had been covered with a layer of 
linseed oil :— 


| | TEMPERATURE BEFORE. TEMPERATURE AFTER. | 
ANIMAL. REMARKS. 
| Rectal. | Cutaneous. Rectal. | Cutaneous. 
PRabpit  .. .| 39°°7 38° | «S28? | S26? Ss] At time of death, 
| | thirty hours after 
| varnishing. 
ea - | fei seBies 35° re Be |} 29° |On the sixth day 
/ | | after varnishing. 
Death on eighth 

| | | day. 

| 


Edenhuizen ?° showed that death followed even when only one-sixth 
of the total cutaneous surface was varnished; he believed that the 
symptoms were due to an alkali which he found in the skin. A further 
advance in knowledge was made when Valentin™ discovered that the 
discharge of carbon dioxide from the lungs was reduced to one-eighth or 


1Gerlach, Aubert, Rohrig, Barratt, loc. cit. 
2 Fubini and Ronchi, Joc. cit. Here other references will be found. 
3 Valentin, Arch. f. physiol. Heilk., Stuttgart, Bd. xi. S. 433. 
4 Compt. rend. Acad. d. sc., Paris, Mars 16, 1837. 
> Notiz. a. d. Geb. d. Nat.-u: Heilk., Weimar, 1841, Bd. xix. 
6 Arch. gén. de méd., Paris, 1841, tome xii. p. 517. 
7 Abhandl. z. Physiol. u. Path., Jena, 1841, S. 66. 
8 Gaz. méd. de Paris, Dec. 6, 1843. 
9 Arch. f. Anat., Physiol., u. wissensch. Med., 1851, S. 431. 
0 Nachr. v. d. k. Geselisch. d. Wissensch. u. d. Georg.-Aug. Univ., Gottingen,” 186], 
PiseZooe 
_ 1 Arch. f. physiol. Heilk., Stuttgart, Bd. ii. S. 433, 


728 CHEMISTRY OF RESPIRATION. 


one-sixth of the normal amount, but that the output of carbon dioxide 
was raised to the normal, and death was prevented, when the tempera- 
ture of the surroundings was kept at 20°-25°. These observations were 
confirmed by Schiff. 

The explanation, however, of these experiments was given in 1868, 
when Laschkewitsch ! showed by calorimetric observations that varnished 
animals gave off an abnormally large quantity of heat, that the cutaneous 
vessels were dilated and the vasomotor nerves appeared to be paralysed, 
that the temperature of the animal fell, and thus caused the character- 
istic symptoms and death. When only one limb of a rabbit was 
varnished, the temperature under the skin of that part was 34°°5, as 
compared with 33°, that of the normal limb; after one hour, the first 
fell to 53°:2, the second to 52°5. Varnished animals wrapped up in 
cotton-wool remained well, and no bad effect was observed when the 
body of a normal rabbit was enclosed for six hours in a cylinder filled 
with hydrogen, the rabbit breathing through a mask over the nose and 
mouth. Laschkewitsch also pointed out that the greater the surface of 
the skin in relation to the mass of the body, the sooner death followed 
varnishing of the skin. This is shown in the experiments which Gerlach 
made upon rabbits and horses, the former dying in thirty hours, the 
latter after seven or eight days. The greater the surface in relation to 
the mass of the body, the greater is the rate of cooling. 

The experiment of varnishing the human body was first made, 
according to Laschkewitsch, by the officials of Pope Leo X., who, 
wishing during the coronation ceremonies to make a child represent an 
angel, gilded the whole of its body; the child, however, died before it 
had fulfilled its part in the ceremony. It is probable that in this 
case the gilding contained some poisonous substance. In 1877, Senator ? 
showed that the whole surface of the human body could be covered with 
an impermeable layer, and that even after remaining in this condition 
for eight or ten days, no disturbance whatever could be observed ; 
no marked change was observed in the temperature, and this explains 
the absence of the symptoms which are observed in animals. The 
human body has little natural covering and the most perfect power 


of regulating its temperature, conditions which do not obtain in most of 
the lower animals. 


Extensive but superficial burns of the skin often cause death, and this, 
according to some observers, is due to interference with the cutaneous respira- 
tion and to retention of waste products, which are normally discharged by the 
sweat. There is, however, very little evidence in support of this view, and it 
is probable that the fatal result in these cases is due to the following factors— 
shock, changes in the plasma and corpuscles of the blood,* excessive loss of 
heat from the hyperemic skin, and disturbed regulation of temperature, owing 
to the absence of the normal sensory impulses from the skin. 


Respiration in the alimentary canal.—The quantity and nature of 
the gases found in the alimentary canal vary under different cireum- 


1 Arch. f. Anat., Physiol. w. wissensch. Med., 1868, S. 61. 
2 Virchow's Archiv, 1877, Bd. Ixx. S. 182; Arch. fr Physiol., Leipzig, 1894, 8. 178. 

° Max Schultze, Arch. Jf. mikr. Anat., Bonn, 1865, Bd. i. S. 26 ; Wertheim, Wien. med. 
Presse, 1868, No. 13: : Ponfick, Berl. ilan. Wehnschr. , 1877, No: 46 ; Centralbl. f. d. med. 
Wissensch.., ’ Berlin, 1880, Nos. 11 and 16; Lesser, Virchow’s Archiv, 1880, Bd. exxix. 
S. 248 ; Hoppe-Seyler, Ztschr. f. physiol. Chem., Strassburg, 1881, Bd. v., S. 1 and 344; 
Tappeiner, Centralbl. f. d. med. Wissensch., Berlin, 1881, Bd. xix. S. 385 and 401. 


RESPIRATION IN THE ALIMENTARY CANAL. 729 


stances, as is shown by the following table, which gives the results 
obtained by Ruge! from the analysis of the gas obtained from the 
rectum of the same man under different conditions :— 


“Titi Sig) a | Ui aieieu. wom 2M) 
Vegetable Diet | Animal Diet 


Gas. | Milk Diet. a aa ee ate 
— 
Oxygen . : b ; | 
Nitrogen . . .| 36°71 | 1896 | 64:41 
|Hydrogn . . . 54°23 | 4°03 0°69 
| Marsh-gas_. : ‘ | | 55°94 |} 26°45 
Carbon dioxide. - | 9:06 | 21°05 8°45 | 
, Hydrogen-sulphide | Trace. 


The distribution of these gases in the different parts of the aliment- 
ary canal was examined by Tappeiner,? in the body of a criminal, who 
had been executed a short time before the examination was made. The 
following are the results :— 


| 
Gas. Stomach. | Tleum. Colon. Rectum. 
| | | 
| Oxygen 9°19 y 
| Es 67-71.°, | 
Nitrogn . . | 74:26 —|J | 7-46 62°76 | 
| 
Hydrogen... | 0°08 3°89 =] 0°46 
} | 
| Marsh-gas | - 0-16 ut Retr 0-08 ei 'y O80. 08 | 
| | 
| Carbon dioxide . | 1631 | 28-40 91°92 | 36-40 


| 


Zuntz, Lehmann, and Hagemann ® found in the gas drawn off from 
the intestine of a living horse about 22 per cent. carbon dioxide, 59 per 
cent. marsh-gas, and 2°) per cent. hydrogen. 

These gases have several sources of origin. Oxygen and nitrogen 
oceur in the air swallowed; hydrogen, marsh-gas, and carbon dioxide 
are formed by the fermentations which take place in the contents of 
the alimentary canal; nitrogen and carbon dioxide, under certain 
conditions, diffuse from the tissues into the intestines, and carbon 
dioxide arises from the neutralisation of the sodium carbonate of the 
intestinal secretions. Further details on the origin of these gases will 
be found elsewhere;* here it is necessary only to consider the part 


! Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1862, Bd. xliv. S. 739. 

2 Arb. a. d. path. Inst. zw Miinchen, Stuttgart, 1886, Bd. i. S. 226. See also Planer, 
Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1860, Bd. xlii. S. 307 ; Hofmann, Wien. med. 
Wehnschr., 1872 ; Tappeiner, Zitschr. f. physiol. Chem., Strassburg, 1882, Bd. vi. S. 432 ; 
Ztschr. f. Biol., Miinchen, 1883, Bd. xix. S. 228; 1884, Bd. xx. 8. 52; Arb. a. d. path, 
Inst. zw Miinchen, Stuttgart, 1886, Bd. i. S. 215. 

° Arch. f. Physiol., Leipzig, 1894, S. 354. 

4 See ‘‘ Chemistry of Digestion,” this Text-book, vol. i. 


730 CHEMISTRY OF RESPIRATION. 


some of them play in respiration. The oxygen in the air swallowed is 
almost entirely absorbed in the stomach; the carbon dioxide is gener- 
ally 20 to 90 per cent. of the gas present in the intestines, and will 
therefore have a partial pressure greater than that of the carbon dioxide 
in the blood and tissues, and will diffuse from the intestines into the 
blood, to be ultimately discharged in the lungs. As regards the 
nitrogen, the quantity present in the alimentary canal is considerable, 
but its partial pressure is generally below that of the atmosphere, and 
of the tissues, and under these conditions there will be a diffusion of 
nitrogen from the blood and tissues into the intestinal tract. It is 
important to remember the presence of nitrogen and marsh-gas in the 
alimentary canal, for thus it is possible to explain those cases in which 
an absorption or discharge of nitrogen has been observed during 
determinations of the respiratory exchange. When carbon dioxide or 
hydrogen-sulphide is injected into the rectum, a portion of the gas is 
absorbed and excreted by the lungs.! 


Paul Bert ? observed that a kitten with ligatured trachea lived twenty-one 
minutes when a current of air was passed through the alimentary canal, 
whereas a kitten of similar age died in thirteen minutes, when the only 
operation performed was ligature of the trachea. A similar absorption of 
oxygen from the alimentary canal probably takes place in man under special 
circumstances ; for swimmers who can remain under water for an exceptional 
length of time, state that they swallow air in addition to taking a deep inspira- 
tion before a dive. 

In warm-blooded animals the alimentary canal plays an unimportant part 
in respiration, but this is not the case in some fish, for all the members of the 
loach family respire partly by the alimentary canal. The air discharged 
under normal conditions from the rectum of Cobitis fossilis has the following 
composition: 87:18 per cent. nitrogen, 12°03 per cent. oxygen, and 0°79 per 
cent. carbon dioxide; but if the fish be prevented ‘from swallowing air for 
several hours, the percentage composition is 91°33 nitrogen, 7°94 oxygen, and 
0-73 carbon dioxide.* Erman* opened the abdomen of one of these 
fish, and noticed that when air was swallowed the intestinal ves and the 
liver became bright red, but with hydrogen or nitrogen the colour was very 
dark purple. The mucous membrane of the intestine of Cobitis fossilis is, 
according to Leydig,® composed almost entirely of capillary blood vessels, and 
a little connective tissue. In the Callichthys asper, a fish found in Brazil, the 
respiration by the alimentary canal is essential for life, for if the fish be 
prevented from coming to the surface of the water to swallow air, it dies 
within two hours. The air discharged by the rectum contains 1:5-3°8 per 
cent. of carbon dioxide.® 

The respiration of the foetus.—The respiration of the foetus was first 
understood and described in 1674 by Mayow,’ who in his treatise, ‘“ De 
Respiratione Foetus in Utero,” maintains that the placenta is to be looked 
upon as a lung; from which the umbilical vessels take up the nitro-aerial gas 


1 Bernard, ‘‘ Lecons sur les effets des substances toxiques et médicamenteuses,” Paris, 
1857, p. 59; Bergeon, Compt. rend. Acad. d. sc., Paris, tome civ. p. 1812; Hanriot and 
Richet, Compt. rend. Soc. de biol., Paris, 1887, p. 307; Flint, Med. News, Phila., 1887, 
vol. li. p. 670. 

2 «* Physiol. comp. de la respiration,”’ Paris, 1870, p. 173. 

3 Baumert, ‘*Chem. Untersuch. ii. d. Respir. d. Schlammpeitzgers,” Breslau, 1855, 
S. 24. 

4 Ann. d. Phys. u. Chem., Leipzig, 1808, Bd. xxx. S. 1138. 

5 Arch. f. Anat., Physiol. u. wissensch. Med., 1853, S. 3. 

§ Jobert, Ann. d. sc. nat., Paris, 1877, Zool. (6), tome v., Art. No. 8. 

7 «Tractatus Tertius, de Respiratione Feetus in Utero et Ovo,” Oxon., 1674. 


RESPIRATION OF THE FQ@TUS. 731 


(oxygen) and carry it to the foetus; at the same time, he recognises that the 
foetus obtains its supply of nutrition in a similar manner. This view of the 
foetal respiration was adopted and extended by Hulse,! and by Ray,’ who 
states his view in the following words :—‘ The maternal blood which flows to 
the cotyledons, and encircles the papilla, communicates by them to the blood 
of the foetus the air wherewith itself is impregnate; as the water flowing 
about the carneous radii of the fish’s gills doth the air that is lodged therein to 
them.” Mayow’s brilliant work was allowed to drop into obscurity, and the 
respiration of the foetus was not understood again until the beginning of this 
century. 

Some physiologists, and among them Leclare* and Geoffroy St. Hilaire,* 
maintained that the liquor amnii served the purpose of respiration by the skin 
of the fetus. Haller,® Hunter,® Osiander,’ Autenrieth and Schiitz,® Emmert,? 
Joh. Miiller,!° and E. H. Weber" stated that no difference could be observed 
in the colour of the blood of the umbilical arteries and vein; on the other 
hand, Scheel,!2 Herissant and Diest,!% Baudelocque,'* Joerg, Jeffray,© and 
Bostock 17 noticed that the blood going from the placenta to the foetus was 
of a more arterial hue than that going in the opposite direction, although 
there was naturally not so marked a distinction as between the arterial and 
venous blood of the adult. 


Even as late as 1840 the respiration of the foetus was not under- 
stood, for Joh. Miller,’ the chief physiologist of the time, held that 
plasma from the mother passed to the foetus, and so supplied the place 
of respiration. Bischoff! looked upon the placenta as an organ of the 
mother, and denied the existence of any special respiration ; this view 
was contested by Litzmann,° who held that the fcetus respired by the 
placenta. Gradually, owing in a great measure to the work of Schwartz,” 
Gusserow,” and Schultze? the truth discovered by Mayow in 1674 was 
re-established, and received a final proof when Zweifel,*4 following the 
suggestion of Hoppe-Seyler, showed in 1876 that the spectrum of 
oxyhemoglobin could be clearly seen in the umbilical cord before the 
child breathed by its lungs; that, by taking the precaution to open the 
uterus of a pregnant rabbit in warm normal saline solution, and thus 


1 Quoted from Ray’s book, p. 73. 

2 **The Wisdom of God in the Creation,” 12th edition, 1759, p. 74. 

34567 Quoted from Miiller, ‘‘Elements of Physiology,” Baly’s transl., 1838, vol. i. 
pp. 317, 320. 

8 «Experimenta circa calorem feetus sanguinem ipsius instituta,” Tubinge, 1799. 

9 Arch. f. d. Physioi., Halle, 1811, Bd. x. S. 122. 

10 “De respiratione fetus,” Lipsiw, 1823, S. 10; ‘‘ Handbuch der Physiologie,” 1840, 
Bd. ii. S. 729. 

11 Hildebrandt’s ‘‘ Anatomie,” Bd. iv. S. 524. 

2 «De liquoris amnii aspere arteri# foctunm humanorum natura et usu,” Hafnie, 
1799: 

13 Haller’s ‘‘ Disputationes,” vol. v. pp. 516, 526. 

M4 Bichat’s ‘‘ Anatomie générale,” tome ii. p. 465. 

15 “Die Zeugung,” Leipzig, 1815, 8. 273. 

16 <* Te Placenta.” 

17 « Physiology,’’ London, 1828, 2nd edition, vol. ii. p. 199. 

18 <¢ Handbuch der Physiologie,” 1840, Bd. ii. S. 729. His words are :—‘‘Die von den 
Blutgefiissen angezogenen Sifte dringen sodann direct ins Blut des Fétus. Durch diese Art 
von Wechselwirkung mit miitterlichen Siften ist bei dem Fetus auch das Athmen ersetzt 
oder ein Aquivalent dafiir gegeben.” ; 

19 «« Entwickelungsgeschichte der Siugethiere und des Menschen,” 1842, S. 541. 

20 «« Weber die Schwangerschaft,” Wagner’s ‘‘ Handworterbuch.” 

21 <« Tie vorzeitigen Athembewegungen,”’ Leipzig, 1858. 

22 Arch. f. Gynaek., Berlin, Bd. iii. 

% Jenaische Ztschr. f. Med. vu. Naturw., Leipzig, Bd. iv. 

24 Arch. f. Gynaek., Berlin, 1876, Bd. ix. 8. 291. 


732 CHEMISTRY OF RESPIRATION. 


prevent vigorous contractions of the uterus, the blood in the umbilical 
vein of the fcetus was brighter than that in the arteries; and that the 
difference in colour of the umbilical vein and arteries disappeared 
during asphyxia of the mother, to reappear when artificial respiration 
was performed. Pfltiger+ had also noticed that the colour of the 
umbilical vein was reddish brown in the normal condition, but became 
black during asphyxia. 

The results obtaimed by Zweifel were confirmed and extended by 
Zuntz,? who showed that during asphyxia of the mother the foetal blood 
lost oxygen in the placenta, the blood of the umbilical vein becoming 
darker than that of the corresponding arteries; that when the maternal 
vessels supplyimg the placenta were compressed the umbilical vein 
became as dark as the arteries; that a foetus respiring air through its 
lungs lost oxygen in the placenta, which was left connected with an ex- 
cised piece of the uterus; that during normal breathing of the mother 
the umbilical vein coming from the intact placenta contained blood as 
red as the arterial blood of the ‘uterus, and that movements of the 
foetus made the blood of the umbilical arteries darker in colour. Zuntz 
maintains that the oxidation taking place in the foetus must be small, 
for the difference in the colours of the umbilical arteries and vein is 
slight, corresponding to a difference of about 1 per cent. im the amount 
of oxygen; and the fcetus can live for a long time upon the oxygen in 
its blood, when respiration by the placenta or lungs is prevented. 
According to Zuntz’s estimate, the human fetus would need daily 
0-169 grm. of oxygen per kilo. of its weight, as compared with 
14-15 grms., the amount required by an adult.? Pfliger* and 
Zuntz found that the blood of the foetus, in comparison with that 
of an adult, had a low specific gravity and was poor in corpuscles 
and hemoglobin ; these results, however, are opposed to those 
of Hayem,? Heesslin,® Sorensen,’ W iskemann3 Preyer,? Denis,” and 
others," who found higher values for the fetus than for the 
mother. 

The difference in the tension of oxygen in the blood of the 
umbilical artery of the fetus and the “maternal blood is small, 
but it is sufficient, owing to the intimate relationship of the 
maternal and foetal circulations, to supply the oxygen needed by the 
foetus.? 

Cohnstein and Zuntz! have analysed the blood of the umbilical 
artery of a foetal sheep, which was 53 cm. long, weighed 1535 germs., 


1 Arch. f. d. ges. Physiol., Bonn, 1868, Bd. i. S. 80. 

* Ibid., Bonn, 1877, Bd. xiv. S. 605. 

* This is contested by Wiener, Arch. 7. Gynaek., Berlin, 1884, Bd. xxiii. S. 183. This 
paper gives numerous references to the work on the general metabolism of the feetus, but 
does not disprove the relatively small oxidation in the foetus. 

4 Arch. f. d. ges. Physiol., Bonn, 1868, Bd. i. S. 61 ; 1875, Bd. x. S. 274. 

° Compt. rend. Acad. d. sc., Paris, 1877, tome Ixxxiv. p. 1166. 

§ Ztschr. f. Biol., Miinchen, 1882, Bd. xviii. S. 612. 

7 Jahresb. ii. d. Fortschr. d. Anat. u. Physiol., Leipzig, 1878, Bd. v. Abth. 3, S. 192. 

8 Ztschr. f. Biol., Miimchen, 1876, Bd. xii. S. 434, 

* ** Specielle Physiol. des Embryo,” Leipzig, 1883, S. 144. 

” Ann. de chim. et phys., Paris, 1842, Sér. 3, tome v. p. 313. 

11 Poggiale, Compt. rend. Acad. d. se., Paris, 1847, tome xxv. p. 112; Panum, 
Virchow's Archiv, Bd. xxix. 8.481. See also Cohnstein and Zuntz, Arch. f. d. ges. Physiol., 
Bonn, 1884, Bd. xxxiv. S. 183. 

12 Zuntz, ibid., 1877, Bd. xiv. S. 626. 

8 Arch. f. d. ges. Physiol., Bonn, 1884, Bd. xxxiv, S. 206, 231. 


RESPIRATION OF THE EMBRYO. rae 


and was probably in the last three weeks of intra-uterine life. The result 
was— 


Oxygen : : d ‘ ; i 6:669 volumes per cent. 

Carbon dioxide. : ‘ . $i 4EDA2Y 5s 9 

Nitrogen. ; 3 : ; ; 1:000 ‘5 a 
Total gas. 4 , en) Daal + - 


Comparative estimations of the gases in the umbilical artery and 
vein were also made, and show that the changes undergone by the blood 
in the placenta are about one-half as marked as in the lungs of an 
adult :— 


Oxygen. Carbon Dioxide. 
Artery : 6°69 vol. p.c. | 45°54 vol. p.c. ) Specimens 
| of blood 
Veins «3 = -\slessithanll-36— .,, ABD) der taken sim- 
| | ultaneous- 
Difference . Ly Vee ee ly. 
Fetal | 
: » ) Sample of 
x i 9-2 e 
Sheep Artery = ys 2°3 +3 47-0 5 | Wiscdl frank 
og - - e _ vein taken 
Venn. | Bo ne ze) 24 minutes 
\ Difference . | ASO 55 6°5 5: ae dae 
romartery. 
‘ie ifference 8°15 vol. p.c. || 9-2 vol. p.c. 
Adult between ven- 
animals ! | ous and ar- 
terial blood 


From these results Cohnstein and Zuntz calculate that the absorp- 
tion of oxygen by a fetal sheep weighing 3600 grms. is 1°75 ¢.c. per 
minute, or, per kilo. and minute, 0-49 ¢.¢., which is about one-twelfth the 
amount absorbed, weight for weight of body, by a full-grown sheep. 


The respiration of the embryo. —The process of respiration in the 
embryo has, owing to the natural difficulties of the subject, been chiefly studied 
in the eggs of birds and of a few reptiles. The absorption of nitro-aerial gas 
(oxygen) “through the porous shell of an egg undergoing incubation appears 
to have been first recognised by Mayow,? but the necessity of respiration in 
the developing embryo was first shown by the experiments ® of varnishing 
the eggs, covering them with oil or warm water ; under such conditions it was 
found that the embryo quickly ceased to develop, and died. If the impervious 
covering was only applied to a portion of the shell, the embryo developed, in 
some cases normally, in others abnormally with the production of deformities 


or monstrosities.* 


' Zuntz, Hermann’s ‘‘ Handbuch,” Bd. iv. Th. 2, S. 37, 

2 <«Tract. quinque,” Oxonii, 1674, pp. 131, 313, 321, 

5 Paris, Ann. Phil., London, 1821, _N.S., Vol. ii. p- 2; Home, Phil. Trans., London, 
1810, p. 213 ; 1822, p. 339 ; Dareste, "Ann. d. sc. nat., Paris, 1855, Sér. 4, Zool. tome iv. 
p. 119 ; Compt. rend. Acad. asco, Paris, 1855, p. 963 : Marshall,. Med. Times and Gaz., 
London, 1840-41, vol. i. p. 242 ; Dusing, Arch. f. d. ges. Physiol., Bonn, 1884, Bd. 
xxxlii. 8. 67. Here other references are given. 

4 Gerlach and Koch, Biol. Centra/bl., Erlangen, 1882, Bd. ii. S. 681. 


734 CHEMISTRY OF RESPIRATION. 


In 1834, Theodor Schwann! showed that, when hens’ eggs are kept at a 
warm temperature in gases containing no oxygen, the germinal membrane 
enlarges, and the area pellucida is formed, but no embryo ; eggs would develop 
normally in warm air, after they had been in hydrogen for twenty-four hours at 
a warm temperature, but not if the exposure to hydrogen had lasted thirty 
hours or more. 

The first determinations of the respiratory exchange in eggs are due to 
Baudrimont and Martin Saint-Anges,? who showed that the eggs of birds and of 
snakes gave off carbon dioxide during incubation, and that the embryos of 
frogs died if placed in water free from air. The quantitative results obtained 
by these observers are not trustworthy, owing to the defective methods of gas 
analysis then in use. The first reliable determinations are those made by 
Baumgartner ° throughout the period of incubation of hens’ eggs. The follow- 
ing table gives some of the results :— 


Loss oF WEIGHT OF EGG. este. RAR as Or ey ABSORPTION OF OXYGEN. 
Day OF | = 
INCUBATION. From the at x : ‘ 
eornentementor we biois in Bee one Rouge me one iat ye Es: 
incubation. | ince | ae 88s. 88: B88. 
| 
| 
Grms. Gris. Grms. Grms. Grms. Grms. 
1 | 0'125 0-009 0°16 0°0074 0°13 
i] 
9 | 1°853 | 0°164 0-048 1°01 0°0360 0°76 
20 10°479 1 0°29. 1), 03560 18°93 0°4435 14°90 
} 
7 ae Me | 1:008 a 0°7317 
(chick free) | 
| | 
| 


Similar experiments were made by Pott and Preyer,* who found that a fertile 
egg, weighing 50 grins., lost in weight about 10°27 grms. during incubation, an 
unfertile one 9°70 grms., and an egg kept at the temperature of an ordinary 
room 1°66 grms., in twenty-one days. The respiratory exchange of a developing 
embryo in an egg weighing 50 grms. was, for periods of twenty-four hours :— 


Day of Incubation. Discharge of Carbon Dioxide. | Absorption of Oxygen. 
Grms. Grms. 
7 0°09 0°09 
| | 
13 | 0°24 0°24 
21 0°86 0°68 


Pott °® also showed that the development of the embryo is not hastened or 
delayed if the egg is incubated in an atmosphere of oxygen. During ineuba- 
tion, it has been proved that the temperature of the embryo, owing to its meta- 
bolism, is slightly warmer than the temperature of its surroundings.® 


l Arch. f. Anat., Physiol. u. wissensch. Med., 1835, S. 121. 

* Compt. rend. Acad. d. sc., Paris, 1843, tome xvii. p. 1343; Ann. de chim. et phys., 
Paris, 1847, Sér. 3, tome xxi. p. 195. 

3 «Ter Athmungsprozess im Hi,” Freiburg im B., 1861. 

4 Arch. f. d. ges. Physiol., Bonn, 1882, Bd. xxvii. S. 320. 

° Ibid,, 1883, Bd. xxxi. 8. 268. 

6 Barensprung, Arch. f. Anat., Physiol. u. wissensch. Med., 1851, S. 126. See also 
‘* Animal Heat,” this Text-book, vol. i. 


RESPIRATION OF DIFFERENT GASES. 735 


In connection with the respiration of the embryo chick, it is interesting to 
find that the air contained in the air chamber of the egg has been stated to 
have a greater percentage of oxygen than that present in the atmosphere. 
Thus Bischof ! found 23°475 volumes per cent. as the mean of four analyses, and 
Dulk ? obtained in one case 25°26, in another case 26°77 per cent. of oxygen. 
Hiifner,® however, has repeated and extended these observations, and found 
the following composition in the air removed from twelve eggs, unincubated, 
and a few weeks old :—Oxygen 18°94, nitrogen 79°97, and carbon dioxide 1:09 
volumes per cent.; and in the case of two goose eggs, incubated for sixteen 
days, oxygen 19°58 and 19°85, nitrogen 79°55 and 78°62, carbon dioxide 0°87 
and 1:53 volumes per cent.; these eggs showed no trace of an embryo. 
Experiments were also made upon the rate of diffusion of gases through the 
egg-shell and the shellsnembrane, and it was found that the rates of diffusion 
of the different gases did not follow Graham’s law; they were not inversely 
proportional to the square roots of the densities of the several gases. 

During the period of incubation of a chick the gradual development of the 
power of heat regulation can be traced. At first the embryo responds to 
changes in external temperature by a similar change in its respiratory ex- 
change—a fall of temperature causes a decrease, a rise of temperature an 
increase, in the respiratory exchange; then for a short time there is an inter- 
mediate condition in which a change of temperature has no marked effect ; and, 
lastly, when the chick is hatched, it responds as a warm-blooded animal.* 

If tadpoles and larve of salamanders (Salamandra maculata) be prevented 
from coming to the surface of the water, their metamorphosis is greatly 
prolonged, and if well fed they will live for a long time as purely aquatic 
animals.° 


THE RESPIRATION OF DIFFERENT GASES. 


Some gases, such as hydrogen and nitrogen, have no specific effect 
when they are respired, and animals supplied with these gases alone die 
simply from want of oxygen. Other gases, such as carbon dioxide, carbon 
monoxide, nitrous oxide, and hydrogen sulphide, can be taken into the 
lungs, and if present in sufficient quantity are absorbed, and produce 
specific effects; while a third class, such as ammonia and nitric oxide, 
are irrespirable on account of their irritant action producing spasm of 
the glottis. 


Oxygen.—Soon after his re-discovery ° of oxygen in 1774, Priestley 
observed, both upon himself and upon animals, the effect of breathing 
the pure gas; in his own case he felt an agreeable facility of respiration, 
and in animals he found that oxygen had a greater power than air in 
supporting life. These experiments were repeated by Lavoisier, 
Higgins,’ Dumas," Beddoes," H. Davy,” Allen and Pepys,” and in some 


1 Journ. f. Chem. u. Phys., Niirnberg, 1823, Bd. xxx. S. 446. 

2 Thid., Halle, 1830, Bd. lviii. S. 363. 

5 Arch. f. Physiol., Leipzig, 1892, S. 467. 

+ Pembrey, Gordon, and Warren, Journ. Physiol., Cambridge and London, 1894, vol. 
xvii. p. 331; Pembrey, tbzd., 1895, vol. xviii. p. 361. 

® Preyer, ‘‘Specielle Physiologie des Embryo,” Leipzig, 1885. 

6 Mayow can rightly claim to have discovered oxygen before 1674. See his ‘‘ Tractatus 
quinque.” 

a <On Air,” yol. 1. p; 162: 

8 Mém. Soc. Roy. Med., 1782, tome ili. p. 576 ; Hist. Acad. roy. d. sc., Paris, 1/89 Spagiss 

® «* Minutes of a Society, etc.,” London, 1795, p. 144. 

10 «« Physiologie,” Paris, 1806, 2nd edition, tome iii. p. 59. 

11“ On Factitious Airs,” Bristol, 1796, part i. p. 13. é 12“ Researches, ” p. 439. 

8 Phil. Trans., London, 1808, pp. 266 and 280; 1809, pp. 415 and 427. 


“A 


[ay | 


736 CHEMISTRY OF RESPIRATION. 


cases irritant effects, probably due to the presence of impurities in the 
gas, were noticed. 

Considerable discussion has arisen concerning the effect of an in- 
creased percentage of oxygen in the air breathed upon the respiratory 
exchange. Is there or is there not an increase in the absorption of 
oxygen and the discharge of carbon dioxide under these conditions ? 
Many observers! maintain that there is a distinct augmentation of the 
metabolism of the body, others? find that the respiratory exchange of a 
normal animal is the same in amount, whether it breathes air or pure 
oxygen. Without entering into a discussion of the numerous con- 
tradictory answers to this question, it is permissible to draw the 
following conclusions:—The normal animal does not increase its 
respiratory exchange when it breathes oxygen instead of air, for its 
metabolism is regulated by the needs of its tissues, and not directly 
by the amount of oxygen absorbed in the lungs; in the case of some 
diseases, during which the blood, owing to diminished absorption of 
oxygen in the lungs, is abnormally venous, the breathing pure oxygen 
would increase the percentage of oxygen in the alveolar air, and thus 
enable the blood in the lungs to take up more oxygen. In these cases 
breathing oxygen under pressure greater than that of the oxygen in 
the air would, for a simular reason, be effective, and would also in- 
crease the amount of oxygen simply dissolved in the plasma. It 
would appear, therefore, that there is strictly no contradiction in 
most of the experimental and clinical results, for in the normal 
anunal breathing ordinary air the arterial blood is almost saturated 
with oxygen, and without doubt contains as much or more oxygen 
than the tissues need. This is certainly not the case in some dis- 
eases, during which the patients have derived benefit from breathing 
oxygen.® 

In connection with the respiration of pure oxygen or of air, Paul 
Bert * made the important discovery that animals exposed to a pressure 
of oxygen above six atmospheres died in violent convulsions. This 
result is not due to the purely physical effects of the increased pressure, 
but to the augmentation in the tension of oxygen, for if the experiment 
be made with air, a greater and greater pressure can be borne, until 


? Allen and Pepys, Phi/. Trans., London, 1808, pp. 266 and 280; 1809, pp. 415 and 
427; Paui Bert, ‘‘ La pression barométrique,” Paris, 1878, p. 832. Further references are 
given by Phillips, ‘‘ Materia Medica, Pharmacology, and Therapeutics—Inorganic Sub- 
stances,’ London, 1894, 2nd edition, p. 2. 

* Lavoisier and Sequin, Hist. Acad. roy. d. sc., Paris, 1789, p. 566 ; Regnault and Reiset, 
Ann. de chim. et phys., Paris, 1849, Sér. 3, tome xxvi. ; Dohmen, ‘‘ Arb. d. Bonner physiol. 
Inst.,” 1865; Speck, Arch. f. d. ges. Physiol., Bonn, 1879, Bd. xix. S. 171; Kempner, 
Arch. f. Physiol., Leipzig, 1884, S. 396; Lukjanow. Zischr. f. physiol. Chem., Strassburg, 
1883-84, Bd. vill. S. 313; Arch. 7. Physiol., Leipzig, 1884, S. 308. See also references 
given by Phillips, Joc. cit. supra. 

* Ransome, Med. Chiron., Manchester, April 1888, May 1889; A. H. Smith, ‘‘ Oxygen 
Gas as a Remedy in Disease,” New York, 1870, 2nd edition ; W. G. Thompson, Practi- 
tioner, London, 1889, vol. xlili. p. 97. At the end of this article is a list of thirty-two 
papers on the subject. See also article ‘‘Oxygene” in “ Dictionnaire de therapeutique, de 
matiere médicale, de pharmacologie, de toxicologie et des eaux minérales,” par Dujardin- 
Beaumetz, Paris, 1889, tome iv. p. 101. See also Phillips, Joc. cit. supra, and references 
there given. 

* Paul Bert, ‘‘La pression barométrique,” Paris, 1878, p. 800. See also Lehmann, 
Arch. f. d. ges. Physiol., Bonn, 1884, Bd. xxxiii. S. 173; Liebig, Arch. f. Physiol., 
Leipzig, 1889, Supp. Bd. 8. 41; A. H. Smith, ‘‘The Effects of High Atmospheric 
Pressure, including the Caisson Disease,’ Brooklyn, 1873 ; Philippon, Journ. de 'anat. et 
physiol. etc., Paris, 1894, tome xxx. pp. 296, 414. 


RESPIRATION OF DIFFERENT GASES. 735 


a point is reached at which the partial pressure of oxygen becomes 
dangerous to life. When the arterial blood contains a third more than 
its normal quantity of oxygen, the metabolism of the body diminishes 
greatly, and the animal dies. The following examples will illustrate 
this effect :— 


Pressure of 


Oxygen Percentage Composition 
* aw 5 
Duration of the | Pressure in in Atmo- of Gases of Blood. Rectal 
Compression. Atmo- spheres. Tempera- Remarks. 
spheres. ture. 
OxP Cnty OF; 
20°9 | 
Air. 20 14°9 Bilal 38°°5 
1? 7 21°4 34°3 
45min. . 7 25 325 | 73°8 #- Dog ; 
: convulsions; 
| Free air 27 bs 1GTON TS)! 210 39°°0 survived. 
min.after. 
Free air 67 a8 17°0 BGs) 
min. after. 
Air. ao 19°8 20°9 38°°5 
. Oxygen. 4°4 20°9 34°5 aes | 
65 min. -Dog ; 
= | 6 24 26°3 62°5 death. 
9 35 30°7 61°5 oa J 
Sparrow ; 
43 convulsions; 
| ° 3 
5 21 = Bas 33 | death a 30 
min. 
Air. apereys ; 
nae convulsions 
ger 21° : 
oJ 21°5 oie wale sale death in 20 
min. 


__ The practical importance of these experiments in connection with the symp- 
toms observed in men after working in caissons is obvious. Details of numer- 
ous cases are given by Paul Bert! and others,? but here it is sufficient to draw 
attention to the chief symptoms and changes observed in men working in 
compressed air. The earliest and most constant symptom is pain and noise in 
the ears, due to the pressure upon the tympanum ; relief is generally obtained 
by swallowing, or by a forced expiration with closed nose and mouth ; in some 
cases, however, the tympanum has been ruptured. The respiration is slower 
and deeper. The danger to life, however, chiefly occurs when the workmen 
leave the caisson and come out into the fresh air ; the symptoms then observed 
are due to the relative fall in atmospheric pressure, and are chiefly these— 
very painful itching of the skin, painful swelling of the muscles and joints, 
disturbances in locomotion and sensation, paralysis of the lower limbs, 
bladder, and rectum, and more rarely extensive paralysis, unconsciousness, 
and sudden death. 


1 Loc. cit., p. 369. 

* See ref. given by Paul Bert, Joc. cit. ; E. H. Snell, ‘‘ Compressed Air Illness or so- 
called Caisson Disease,” London, 1896; Heller, Mager, Schrotter, Centralbl. f. Physiol., 
Leipzig u. Wien, 1896, No. 2, S. 40; Friedrich and Tauszk, Wien. klin. Rundschau, 1896, 
S. 233. 


VOL. I.—47 


738 CHEMISTRY OF RESPIRATION. 


It is impossible to discuss here the different theories! brought forward to 
explain the symptoms, but it appears that the most probable explanation is 
that given by Bucquoy,? who maintains that the sudden fall in pressure sets 
free the excess of gases dissolved in the blood during the exposure to the 
compressed air of the caisson. These particles of gas in some of the small 
blood vessels would cause embolism, and this would especially affect the nervous 
system. Great support is given to this theory by the fact that workmen rarely 
suffer when the change from the compressed air to the open air takes place 
gradually by a slow fall in pressure, and that the most effective treatment for 
the more serious symptoms is the subjection of the patient to compressed air. 
This treatment * has been carried out in cases occurring among the workmen 
employed in the construction of the Blackwall Tunnel under the Thames. 


In experiments upon animals, Paul Bert * found that the production 
of carbon dioxide was diminished both when the animal was exposed 
to a high or to a low atmospheric pressure. Lowy, however, observed 
no alteration in the respiratory exchange of man, until the pressure of 
the air fell below 300 mm. There was then an increase in the discharge 
of carbon dioxide, but no corresponding increase in the intake of 
oxygen.° 

A gradual fall in the atmospheric pressure acts upon animals only 
by decreasing the tension of the oxygen in the air, for, if the percentage 
of oxygen be raised, a lower pressure can be borne. In air, discomfort 
is felt when the pressure is reduced to half an atmosphere, and the 
symptoms become violent with a pressure of 250 mm.; conyulsions, 
insensibility, and death supervene. The limit of pressure appears to be 
about 200 mm. Such are the results obtained by Paul Bert ® during 
experiments upon animals, and they agree with those observed upon man 
during balloon ascents. Thus during the ascent of the Zénith™ to a 
height of 8600 metres, Sivel and Crocé-Spinelli died, Tissandier became 
unconscious, but recovered during the descent; the pressure at that 
height would correspond to 260 mm., and the tension of oxygen to 52 
mm. According to Paul Bert’s observations, the oxygen in the arterial 
blood would be reduced to 10 volumes per cent. 


Many theories have been put forward to explain the symptoms of 
“mountain sickness,” but the true one appears to be that of Jourdanet, who 
maintains that it is due to a condition of anoxyhemia, a want of sufficient 
oxygen in the blood.S In these cases the absorption of oxygen by the blood 
would, at the low pressure of the atmosphere, be insufficient for the needs of the 
tissues of a man or animal engaged in the exertion of climbing. It has been 
objected ® that this explanation is incorrect, because there appeared to be no 
decrease in the amount of oxygen in the blood of dogs, which were subjected 
by Frankel and Geppert to a reduced pressure, equal to’ that of an altitude of 


1 For further details, see Paul Bert’s work, Zoc. cit., p. 520. 
2 “* De air comprimé,” 1861. 3 Snell, Zoc. cit. 

4 Loc. cit., pp. 727, 805. 

° For observations upon the effect of reduced atmospheric pressure on respiration, see 
G. v. Liebig, Miinchen. med. Wehnschr., 1891, Bd. xxxviii. S. 487; Lowy, Arch. f. 
Physiol., Leipzig, 1892, S. 545; Speck, Zéschr. f. klin. Med., Berlin, Bd. xii. S. 447. 

6 «« La pression barométrique,” Paris, 1878, p. 735. 

7 Paul Bert, doc. cit., p. 1061; Tissandier, Nature, Paris, 1875, p. 337. 

8 A full discussion will be found in Paul Bert’s work, Joc. cit., p. 327. See also Clifford 
Allbutt, ‘‘System of Medicine,” London, 1897, vol. iii. p. 456. For the effects of high 
altitudes upon the number of coloured blood corpuscles, see article on ‘‘ Blood,” p. 150. 

* Grawitz, Berl. klin. Wehnschr., 1895, S. 713 and 740. 


CARBON DIOXIDE. 739 


16,000 ve This may be so during rest, but it is probable that, on exertion, 
the slower rate of absorption would lead toa deficiency in oxygen ; ‘the organism 
accommodates, not for a condition of rest, but for exertion also ; it has a reserve 
store of energy. Thus,a man with marked anemia, when he is at rest, absorbs 
as much oxygen and produces as much carbon dioxide as a healthy man at 
rest, but, directly marked exertion is necessary, the anemic subject becomes 
breathless ; he has no reserve upon which to draw during the greatly aug- 
mented metabolism which accompanies muscular work. 


Nitrogen.—This gas appears to be quite inactive, and an animal 
confined in it dies from want of oxygen. The same seems to be true 
for argon. Nitrogen containing 5 per cent. oxygen was found by Sir 
George J ohuson? to produce satisfactory anesthesia in man within a 
minute ; this result is also to be attributed to want of oxygen. 

The question of the absorption or discharge of nitrogen by the lungs 
has been discussed in another part of this work. 

Hydrogen.—Numerous experiments have been made upon the 
effects of respiring hydrogen, and the general conclusion is that it 
produces no specific effect, “but acts only ‘by the exclusion of oxygen.? 
Lavoisier and Seguin found that guinea-pigs respired in a normal 
manner in a mixture of equal parts of oxygen and hydrogen, and similar 
results were obtained upon dogs, rabbits, and frogs by Regnault and 
Reiset. Many cold-blooded animals can live for several hours in pure 
hydrogen.* 

Carbon dioxide.—This gas in an undiluted state is irrespirable on 
account of the spasm of the glottis which it occasions, but when sufti- 
ciently diluted with air or oxygen it can be respired, and produces head- 
ache, slight giddiness, drowsiness, and hyperpncea. Some of the earliest 
experiments with this gas were made by Priestley,? who found that cats 
died from suffocation when placed in carbon dioxide, and butterflies when 
held over the fermenting liquor in a brewery became motionless in a few 
minutes, but revived on being brought into the fresh air. Since that 
time numerous experiments have been made by different observers,® 
especially by Paul Bert, whose results will be mentioned later. Brown- 
Séquard and d’Arsonval’ state that they were able to breathe air 
containing 20 per cent. of pure carbon dioxide for two hours without 
any marked distress, but it is probable that there was some error in this 
observation, for Haldane and Lorrain Smith® found that when they 
breathed air containing 18°6 per cent. of this gas the following effects 
were produced within a minute or two—hyperpneea, distress, flushing, 
cyanosis, and mental confusion. Haldane ® has further investigated this 
gas in connection with the suffocative gas found in wells and the 
“)black-damp ” of mines. 

u Laneet, London, 1891, vol. i. 

* Scheele, ‘‘On Air and Fire,” trans. by Forster, London, 1780, p. 160; Fontana, 
Phil. Trans., Uondon, 1779, vol. lxix. p. 337; Journ. de phys., Paris, tome xv. p. 99 ; 
Pilatre de Rozier, ibid., tome xxviii. p. 425; Lavoisier, Hist. Acad. roy. d. sc., Paris, 1789, 
p. 574; H. Davy, ‘‘ Researches,” p. 465; Allan and Pepys, Phil. Trans., London, 1809, 

SB 
iss Edwards, Johannes Miiller. See this article, p. 781 

+ Pilatre de Rozier, Jowrn. de phys., Paris, tome xxvili. p. 422. 

Phil Trams, London, 1772, vol. ‘lsii. p. 147. 

6 For references, see ee Arch. f. Physiol., Leipzig, 1896, S. 408. 

7 Compt. rend. Acad. d. , Paris, 1889, 11th Feb. 

8 Journ. Path. wand Bacteetl: Edin. and London, 1892, vol. i. p. AGS 


® Trans. Fed. Inst. of Mining ’ Engineers, 1895, vol. viii. p- 549. ‘* The Causes of Death 
in Colliery Explosions,” Government Blue Book, "1896. 


740 CHEMISTRY OF RESPIRATION. 


Speck ! found, when he breathed a mixture of gases containing 11°51 
per cent. of carbon dioxide, that 528 c.c. carbon dioxide were absorbed by 
the blood in a minute, whereas under normal conditions 230 e.e. of that 
gas would have been discharged. In a dog Pfliiger? found that there 
were, under normal conditions, 29°8 volumes per cent. carbon dioxide * 
in the arterial blood, but 56°8 volumes per cent. after the dog had 
breathed for one minute a mixture containing 70 per cent. oxygen 
and 30 per cent. carbon dioxide. Zuntz* observed an increase to 
89°6 volumes per cent. carbon dioxide when a dog breathed for one 
minute and a half a mixture containing 36°9 per cent. carbon dioxide. 

_ Numerous experiments were made by Paul Bert*® upon the action of 
this gas upon different forms of life. He found that a percentage of 13°5 
to 17 was fatal for reptiles, 24 to 28 for sparrows, and 30 or more for 
mammals. When the air contained 30 to 40 per cent. of carbon dioxide, 
death resulted owing to the high tension of the gas in the blood; thus in 
some dogs the percentage of carbon dioxide in the arterial blood was 
116, in the venous blood 120. Complete insensibility could be produced 
long before any danger to life arose, and thus the gas mixed with air 
or oxygen could be used for the production of anzesthesia.® 

Carbon monoxide.—The physiological action of this gas is of the 
utmost practical importance, since it is every year the cause of 
numerous deaths in cases of poisoning from coal gas, the fumes of kilns 
and coke fires, and in the air of coal mines, especially after explosions. 
Although it has long been known that carbon monoxide is poisonous, 
it was about the year 1857 that Claude Bernard? and Hoppe-Seyler § 
first pointed out that the carbon monoxide displaced the oxygen of 
the blood by forming a more stable compound with hemoglobin, and 
thus brought about asphyxia.® The action of this gas has been studied 
by many observers.!° 

The most recent investigations are those of Haldane,!! who has 
experimented both upon himself and upon mice. The following are his 
chief conclusions :—The symptoms produced in man do not become 
sensible until sufficient carbonic oxide has been absorbed for the 
corpuscles to become about a third saturated; with half saturation of 
the corpuscles the symptoms become urgent. The symptoms are due 
solely to deficiency in the percentage of oxygen in the blood, and are 
similar to those experienced by mountaineers and balloonists at high 
altitudes. The time required for the symptoms to appear in different 
animals is proportional tothe respiratory exchange per unit of body weight, 
and is about twenty times as long in a man as ina mouse. Hence 
it is possible with safety to use a mouse as an indicator of the presence 
of poisonous proportions of carbonic oxide in the atmosphere of a coal- 

1 Centralbl. f. d. med. Wissensch., Berlin, 1876, No. 17. 


2 Arch. f. d. ges. Physiol., Bonn, 1868, Bd. i. 8. 103. 

3 Measured at 0° and 1 m. 

4 Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xlii. S. 408. 

> “La pression barométrique,” Paris, 1878, p. 982. This article, pp. 743-45. 

° See also Gréhant, Compt. rend. Soc. de biol., Paris, 1887, p. 542. 

*“Lecons sur les effets des substances toxiques et médicamenteuses,” Paris, 1857, p 
184; ‘‘Lecons sur les liquides de l’organisme,” Paris, 1859, tome i. p. 365 ; tome li. p. 427. 

8 Virchow’s Archiv, Bd. xi. S. 228; Bd. xiii. S. 104. 

® This Text-book, article ‘‘ Hemoglobin.” 

 Gaglio, Arch. f. exper. Path. u. Pharmakol., Leipzig, 1887, Bd. xxii. S. 233; Gruber, 
Arch. f. Hyg., Miinchen u. Leipzig, 1883, Bd. i. 8. 145; Welitschkowsky, ibid., S. 210; 
Fokker, dbid., S. 503 ; Gréhant, ‘‘ Les poisons de l’air,” Paris, 1890. 

" Journ. Physiol., Cambridge and London, 1895, vol. xviii. p. 430. 


AIR VITIATED BY BREATHING. 741 


mine. Distinct symptoms are produced by air containing ‘05 per cent. 
of the gas, and urgent symptoms with ‘2 per cent. The poisonous 
action diminishes as the tension of oxygen increases, and vice versd. Ata 
tension of two atmospheres of oxygen this poisonous action is abolished 
in the case of mice, and this disappearance of the poisonous action is 
due to the fact that at high tensions of oxygen the animals can dispense 
entirely with the oxygen-carrying function of hemoglobin, and can 
obtain enough oxygen from the gas dissolved in the plasma of the 
blood. 

As regards the gases of the blood, after poisoning with carbon 
monoxide, Gréhant! found that 100 c.c. of blood from the carotid of a 
poisoned dog contained 6 c.c. of oxygen, 30°3 ¢.c. of carbon dioxide, and 
20 e.c. of carbon monoxide; whereas a sample of blood taken before the 
administration of the gas yielded 19°5 cc. of oxygen and 44-2 cc. of 
carbon dioxide. The following figures show the effect of different doses 
of carbon monoxide upon the gases of the blood of dogs poisoned by the 
gas :— 


GASES OF BLoop. 
CO tN INSPIRED AIR. 


| 
| 


Co.. 0». N, co. 

1in 1000. . | 28-9p. ct. 12-2p.ct.| 1:5 p.ct. | 5°5 p. ct. 

Y,, 2000:. Beers otore natu. < irs) oa 
| 

1, gg, 20005 mien eaten YA sat 9°89 ay: (:AeEice | 
} 

PY, 40d0-S)-gi* page | > a se 


The administration of small doses of carbon monoxide, enough to 
produce unconsciousness, causes a marked reduction in the respiratory 
exchange” of a mouse, and its temperature falls. 

According to Gaglio? carbon monoxide present in the blood is not 
oxidised, but St. Martin* states that it is slowly oxidised in the 
presence of oxyhemoglobin. The compound of this gas with hemo- 
globin is partly dissociated in sunlight,? but upon these points more 
details will be given in the discussion upon the gases of the blood. 

The respiration of air vitiated by breathing.—The air vitiated 

by respiration, as in overcrowded rooms, is distinctly unwholesome, but 
the causes of this deleterious action are not simple, but may arise from 
substances given off either from the lungs by respiration, from the body 
by perspiration, or from the injurious products of disease or filth. 

Even as early as 1674, Mayow® had stated that an animal died if 
kept in a limited quantity of air, because it had used up the respirable 
portion, the nitro-aerial gas (oxygen); he further pointed out that re- 
spiration and combustion produced similar changes in the air. About 
the year 1726, Stephen Hales’? observed by experiments upon himself 


1 Compt. rend. Soc. de biol., Paris, 1892, p. 163. 

? Haldane, Journ. Physiol., Cambridge and London, 1895, vol. xviii. p. 430. 
3 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1887, Bd. xxii. 8. 233. 

4 Compt. rend. Acad. d. sc., Paris, 1891, tome exii. p. 1232. 

° Haldane, Joc. cit. 

6 «* Tractatus quinque,” Oxonii, 1674. 

7 “* Statical Essays,” 2nd edition, vol. i. p. 236 ef seq. 


742 CHEMISTRY OF RESPIRATION. 


that the “noxious vapours” produced by repeatedly breathing the same 
air could be removed by potash, and the air rendered fit for respira- 
tion. A few years later, Black? showed that the “noxious vapours ” 
were carbon dioxide. 

The importance of the several factors mentioned above has been differ- 
ently estimated by various observers.?, Brown-Séquard and d’Arsonval ® 
concluded that volatile poisons were given off from the lungs of healthy 
men and animals, for they found that the condensed vapour of breath 
caused death when injected into rabbits; that rabbits made to breathe 
air vitiated by the respiration of other rabbits until the carbon dioxide 
was 2 to 6 per cent., died, unless the supposed volatile poisons were 
removed by previously passing the air over pumice soaked in sulphuric 
acid; that no bad effects were produced when men breathed for an 
hour or two air containing 20 per cent. of pure carbon dioxide. 
The experiment of injecting the condensed vapour of breath has been 
repeated by Dastre and Loye,* Hoffmann-Wellenhof,> Lipari and Crisa- 
fulli,® and Lehmann and Jessen,’ but the results were negative. 

Richardson * maintained that breathed air was poisonous, even though 
all the carbon dioxide and other impurities had been removed; the cause 
he considered to be “ devitalised oxygen,” whatever that term may mean. 
Jackson ® thought that carbon monoxide was the poison. From experi- 
ments performed upon himself, Angus Smith ?° concluded that air vitiated 
by respiration until it contained 1 per cent. carbon dioxide, produced 
distinct feelings of discomfort. 

Experiments, however, performed by Hermans" have shown that 
no volatile poisons are given off by respiration, and more recently 
Haldane and Lorrain Smith,? in an investigation of the subject, both 
as regards animals and men, have confirmed and extended Hermans’ 
work. The following are the chief conclusions given by Haldane and 
Lorrain Smith :-— 

“1. The immediate dangers from breathing air highly vitiated by 
respiration arise entirely ‘from the excess of carbon dioxide and 
deficiency of oxygen, and not from any special poison. 

“2. The hyperpnoea is due to excess of carbon dioxide, and is not 
appreciably affected by the corresponding deficiency of oxygen. The 
hyperpneea begins to appear when the carbon dioxide rises to from 
3 to 4 per cent. At about 10 per cent. there is extreme distress. 

«3. Excess of carbon dioxide is likewise the cause, or at least one 
cause, of the frontal headache produeed by highly vitiated air. 

“4. Hyperpnoea from defect of oxygen begins to be appreciable when 
the oxygen in the air breathed has fallen to a point which seems to 


1 “Tectures on Chemistry,” ed. Robison, Edinburgh, 1803. 

2 See Merkel, Arch. f. Hyg., Miinchen u. Leipzig, 1892, Bd. xv. S. 1, where further 
references are given. 

3 Compt. rend. Acad. d. sc., Paris, 1888, tome cvi. pp. 106, 165 ; Compt. rend. Soc. de 
biol., Paris, 1887, p. 814; 1888, pp. 33, 90, 99, 151. 

+ Tbid., 1888, pp. 43 and 91. 

5 Wien. klin. Wehnschr., December 13, 1888. 

§ Bull. gén. de therap. ete., Paris, 1889, No. 46, p. 524. 

* Arch. f. Hyg., Miinchen u. Leipzig, 1890, Bd. x. S. 367. 

8 Brit. Med. Journ., London, 1860, vol. ii. ; Chem. News, London, vol. lv. p. 253. 

9 **Proc, Physiol. Soc.,” December, 1887, in Journ. Physiol., Cambridge and London, 
vol. ix. 

10 <« Air and Rain,” p. 180. 

Arch. f. Hyg., Miinchen u. Leipzig, 1883, Bd. i. 

2 Journ. Path. and Bacteriol., Edin. and London, 1892, vol. i. p. 175. 


ASPHYXIA IN A LIMITED QUANTITY OF AIR. 743 


differ in different individuals. In one case the hyperpncea became 
appreciable at about 12 per cent., and excessive at about 6 per cent.” 

These observers also point out that the odorous substances arising 
from want of cleanliness of the body or the room, are also causes of the 
discomfort experienced in breathing the air of an overcrowded room. 

The causes of asphyxia in a limited quantity of air.—A 
warm-blooded animal confined in a limited quantity of air soon gives 
signs of discomfort; it becomes restless, breathes more rapidly, and 
soon pants for breath. This stage is succeeded by one during which 
the animal is quieter, breathes more slowly but more deeply ; it becomes 
less sensitive, and falls down; agonising efforts are made to breathe, the 
nostrils are dilated, and the mouth is open. The animal now becomes 
unconscious, its pupils are dilated, it gives a few slight and irregular 
respirations, it is seized by convulsions, and then, after a shght pause, its 
limbs are stretched out with a convulsive shivering movement, its head 
is thrown back, and it dies. 

The general phenomena of asphyxia are described elsewhere in this 
work ;1 here it is necessary to consider only the chemical changes in the 
air, the alterations they produce in the respiratory exchange of the 
animal, and how they cause its death. Upon these questions numerous 
experiments have been made.? 

The duration of life in a limited quantity of air depends upon 
various conditions, such as the amount and temperature of the air, the 
nature and age of the animal. The following table of some of Paul 
Bert’s experiments will illustrate the influence of some of the above con- 
ditions, and will show the composition of the air at the time of death :— 


] 
| Percentage Composi- 
: tion of Air at the 
Animal. a eae pune Duration of Life. time of Death. 
| Oz CO2z 
Mamsats— | 
Cat, 1850 grms. : 25° 5000 c.c. | 25 min. | 3:4 Lif 
Kitten, 5 days old, 130 15" 1000 ,, | 43 to 63 hrs. | . 2°0 16°6 
Bulls 
Kitten, 24 hours old, 125 | 11° 435 ,, | 1 hr. 15 min. 3°0 14°8 
grms. 
Hedgehog, young, 115 25° 1500 ,, | 1 hr. 15 min. 4:0 14:0 
rms. 
Beionse, hibernating, | 12° 390 ,, | About 1 day 22, 14°6 
50 grms. 
Rat, white, 115 grms. . 14° 1450) pee 32min: 11:0 
a Bee E Ey Pahl inet a 1600 ,, | Between2and | 2°2 17°8 
3 hrs. 
me e adult P 30°-35° | 2000 ,, | 20 min. | 11°8 6°5 
,, three days old, 2D 100 ,, | More than 6 hrs. 0°75 17°0 
5 grms. 
Rabbit, young, 200 grms. 25° | 6000 ,, |Alivebutinsensi-| 1°9 134 
ble after 6 hrs. | 
Birps— + 
Sparrow, 23 grms. : 16° 300 ,, | 1 hr. PBs: 13°3 
Finch, 25 grms.  . : 1s 428 ,, | 21 min. 5-0 12°4 


1 Article ‘‘ Mechanism of Respiration,” this Text-book, vol. ii. 
? Edwards, ‘‘ De V’influence des agens physiques sur la vie,” Paris, 1824; Collard de 


744 CHEMISTRY OF RESPIRATION. 


Before any conclusions are drawn from the results given in the 
foregoing table, it will be advisable to consider the cause or causes of 
death in these cases of asphyxia. Do the animals die from a want of 
oxygen, or are they poisoned by the accumulation of carbon dioxide ? 
In order to answer this question, experiments have been made on the 
duration of hfe of animals confined in air containing an excess of 
oxygen, or an excess of both oxygen and carbon dioxide. Many 
observations have been made by various physiologists, but the most 
complete are those of Paul Bert.! The following table gives some of 
his results :— 


An Atmosphere containing an Excess of Oxygen. 


| 
Percentage 
Composition of 
Gases before 


Composition of 
Gases at the 


Animal. Tempera- Volume of | the Experiment.) Duration of Life. time of Death. 
ture of Gases. 
Gases. 
O. N co, oO. 
WarnM-BioopED—- 
Cat, young, 250 | 255 1800 c.c.| 55°5 | 44°5 | 3 hrs. 25 min. | 31 16 
orms. 
Rat, adult, 80 14 =| 500,, | 77 | 23 |1hr 45min. | 20 | 50 
grms. | | 
Rat,6 weeks old, | 25, HD Lae 466 34214 ]| 2 hrs. 29°5 26 
50 grms. 
Rat, 4 days old. 22° 120° 5.) || ol 19 |18 hrs. 30 min.| 28°5 an 
Rabbit, young, 22° | 1400 ,, | 71 | 29 |Morethan 5 hrs.| 438°5 11 
200 grms. | 
Sparrow, young | 25F |. FOO 55. lev) ea piers than 5hrs.| 29 
| | 
| | | 
CoLp-BLoopEp— | 
Grass snake, A S1/ Bp | 17 23 8 days 13°5 61 
| Grey lizard sf. 27°=—29° 510s, 19.121 70 hrs. Dei “ee 
Toad ot |) G=7° | S400R 11100) Mie aqeaayes 17 81 
Frogs : Sully Gi 400 ,, see as | Sidays 13°7 8 


A consideration.of the following results leads to the conclusion, held 
by Mayow ? as early as 1674, that a warm-blooded animal confined in a 
limited quantity of air dies from the want of oxygen, and this con- 
clusion is supported by the fact that its blood is markedly venous 
and contains little or no oxygen. The percentages of oxygen and of 
carbon dioxide in the air at the time of death are about 3 and 
15 respectively. On the other hand, when there is in the air an 
abnormal excess of oxygen, and at the same time a great augmenta- 
tion of carbon dioxide, the warm-blooded animal dies from poisoning 
with carbon dioxide, and here again the conclusion is strengthened by 


Martigny, Arch. gén. de méd., Paris, 1827, tome xiv. p. 203; Snow, Edin. Med. 
Journ., 1846, vol. lxv. p. 49; Claude Bernard, ‘‘Lecons sur les effets des substances 
toxiques et médicamenteuses,” Paris, 1857 ; W. Miiller, Ann. d. Chem. u. Pharm., 1858, 
Bd. eviii. S. 257; Valentin, Zischr. f. rat. Med., 1861, Bd. x. 8S. 33; Beau, Arch. gé&n. de 
méd., Paris, 1860, Sér. 5, tome xvi. p. 64; 1864, Sér. 6, tome iii. p. 1; Paul Bert, 
‘*Lecons sur la physiol. comp. de la respiration,” Paris, 1870, p. 510. 

? “Tecons sur la physiol. comp. de la respiration,” Paris, 1870, p. 518. 

* “ Tractatus quinque,” Oxonii, 1674. See also this article, p. 741. 


ASPHYXIA IN A LIMITED QUANTITY OF ATR. 745 


the fact that the blood of the animal is generally arterial in colour. 
The fatal amount of carbon dioxide appears to be about 25 per cent. 


An Atmosphere containing an Excess of Oxygen and of Carbon Diowide, 


r ntag ‘ oye 
Composition Composition 
Tempera- : ie ee oe ; time of Death. 
Animal. ture of \ olume of e Experiment.| Duration of Life. 
Gases! Gases, 
@.) IHCO;. CO.. iar, 
W Arm-BLooprp— 
Rat, 1 month old. | 25° 550 c.c. | 90 10 | 4hrs. 22°5| 77-5 
32 grms. 
Rat, 1 month old 25s 600 ,, 75 25 | 20 min. PASTS NN TRIS) 
Rat, 3 days old, 25F SOF 80 20 |\Morethan 5hrs.| 29°5 
5 grms. . 
Mouse, young, Ds Wes) Ae 90 10 |Morethan 5hrs.| 24°5 
5 grms. | 
CoLp-BLoopED— 
Grey lizard : 25°-29 550 ,, 90 10 | 26 hrs. 16 
inc i ie 95°-29° | 550 ,, 90 | 10 | 20 ,, 17 
| 


In the cold-blooded animals a marked difference is observed; death 
in such experiments is generally due to an excess of carbon dioxide, and 
the fatal percentage, about 16,is much lower than in the case of the 
warm-blooded animals. 

Important differences have also been observed by Edwards? and 
Paul Bert * in the duration of life; under water, of animals of different 
species, and in animals of the same species, but of different ages and 
exposed to various degrees of external temperature. See table on p. 746. 

The importance of these observations les in the fact that they con- 
firm many of the results obtained by experiments upon the respiratory 
exchange of different animals. Thus an examination of the above tables 
shows that the small animals die more quickly than the big animals, 
and it has been proved that weight for weight they have a more rapid 
metabolism. Further, a marked difference is observed in hens and 
ducks, for the latter can live under water three or four times as long as 
the former. The explanation of this fact is, according to Paul Bert,® to 
be found in the relatively greater quantity of blood in a duck. A 
similar condition appears to obtain in the seal and whale,® which can 
remain under water from fifteen to thirty minutes. 

The tables also show that new-born animals born helpless and blind 
resist submersion for a much longer time than adults, a fact known and 
studied by Harvey,’ HallerS Buffon,® and Legallois,!° but the duration of 


1 Bernard, quoted from Paul Bert, oc. cit. p. 522. 
2 “De influence des agens physiques sur la vie,” Paris, 1824, pp. 629-632. 

3 Loc. cit., p. 534. 

4 This article, p. 720. See also ‘‘ Animal Heat,” this Text-book, vol. 1. p. 852. 

5 Loc. cit., p. 550. 

6 Burdach, ‘‘ Traité de physiologie,” trad. par Jourdan, tome vi. p. 122. 

7 <¢T)e Generatione,” Amst., 1651. 8 «*Elementa physiologie,”’ 1761, p. 316. 
9 < Fistoire naturelle de Vhomme.” 

10 «* Huvres de Legallois,” Paris, 1824, tome i. p. 93. 


746 CHEMISTRY OF RESPIRATION. 


life under water is much shortened when the temperature of the water is 
high. The explanation of this is to be sought in the fact that the respi- 
ratory exchange of these immature animals is relatively small, and rises 
and falls with the external temperature.! 


Animal. pe of 2a a Remarks. Observer, 
Water. r 
MamMMALS— Min. Sec. 
Dog . : - 2 Bis 4 25 | Mean of three experiments. | Paul Bert. 
,», five days old : 0? 2! 585 7 | “two i Edwards. 
eat 4: 22°°5 55 30 id 4 
Cat, two months old . bas 2 50 | a Paul Bert. 
,, two days old ' 0° 4 33 ay) snine 5 Edwards. 
i 5, Sr 10 23 ,, three % 7 
99 5 set) £20 B8 45 3) TO 55 a5 
és i .| 26° 34 30 ¥. ff 
=a a i 30° 4 29°40 5, YEO “5 = 
oS 3 a maze N27 5 four = = 
Kitten, very young .| 14° 27 30 Paul Bert. 
i ° . | 20° 26 0 “ 
¥ $5 fiwoe? of) 1 oaee Lon » 
d a G36? Abb.) tiny ap fe 
Seal, 1 metre long : Le 15-28 0 | $< s 
Rabbit : ; eA gees! a 3 0 Mean of six experiments ; 5 
| rabbits without food for 
| previous twenty - four 
| hours. 
| FAR st : ; APab ads 2 53 | Mean of three experiments ; A. 
| | rabbits well fed pre- 
viously. 
Guinea-pig . : a 0 Bee 3 
% adult : 3 35 | Mean of three experiments. | Edwards. 
“3 two to three By e25q) sat) SUK 56 3 
days old 
Brrps— 
Sparrow. ‘ = la On 0 30. Mean of seven experiments. Bu 
oe) 0 = : 20° 0 46 ie) 9 ” 9 
a : : 2) 40" 0 39 ee Sux ia 35 
if : : 5 Sie | a SEW a Paul Bert. 
Pigeon ' 5 1; LES lsiieee. Pueive a 
Hen . : ‘ 4 Ber Ae ee es: L | — 
Duck . ib ply, >» eight x3 a 


The practical importance of these experiments in connection with 
the cases of suspended animation in children at birth, and in adults 
after drowning, is obvious.? 


THe EXCHANGE OF GASES BETWEEN THE BLOOD AND THE AIR IN 
THE LUNGS—EXTERNAL RESPIRATION. 


The mechanism of the ventilation of the lungs is described in 
another part of this work;* here it is necessary only to discuss the 
frequency and volume of inspiration and expiration, the capacity of the 


1 This article, p. 713. See also ‘‘ Animal Heat,” this Text-book, vol. i. p. 865. 
= «*Report of the Royal Humane Society,” 1865, p. 31. 
3 “* Mechanism of Respiration,” this Text-book, vol. ii. 


FREQUENCY OF RESPIRATION IN MAN. 747 


lungs, and other factors which bear upon the composition of the air in 
the lungs. 

The frequency of respiration in man.—Under normal conditions 
this could be readily and exactly determined, were it not liable to 
variations as soon as the attention of the subject is directed to the 
breathing. Apart from this, the most important causes of variations 
in the frequency of respiration are age, exercise, and temperature. 

Age.—The frequency of breathing decreases from birth to old age, 
as shown by the following table, the result of three hundred observations 
made by Quetelet! upon human subjects of the male sex. 


RESPIRATIONS PER MINUTE. 


AGE. 
| Maximum. Minimum. | | Mean. 
Newly-born 70 23 44 
5 years ~. 32 she 26 
15-20, 24 16 | 20 
fra0-25°))., 24 14 18°7 
25-30, 21 15 16-0 
30-50, 23 11 18-1 


In healthy infants the respiration is very irregular in frequency, 
and often of the Cheyne-Stokes type.* 


The average frequency of respiration in 1897 adult males was found 
by Hutchinson? to be 20 per minute, one-third of the cases breathed 
at that rate, and 1731 between 16-24 per minute. 

Exercise increases not only the frequency but also the depth of 
breathing. This hyperpnceea is not due to a deficiency of oxygen or an 
accumulation of carbon dioxide in the blood, but probably to some pro- 
duct which is derived from the metabolism in the muscles, and stimulates 
the respiratory centre.* 


The physiological explanation of the condition, well known to athletes as 
“second wind,” appears to be unknown; during violent exercise, such as 
running or rowing, there is, after a time, considerable dyspnoea, but if the 
exercise be continued this discomfort disappears, sometimes quite suddenly ; 
the man has now got his “second wind,” and can continue the exertion in com- 
parative comfort. The dyspnoea in these cases appears to be partly cardiac, 
for the pulse-rate may be more than doubled, but when the ‘‘second wind” is 
obtained, there appears to be a marked decrease in the frequency of the heart’s 
contraction.° The causes of this accommodation are unknown. 


1 «Sur Vvhomme et le développement de ses facultés,” Paris, 1835. 

2 See Preyer, ‘‘Specielle Physiologie des Embryo,” Leipzig, 1885, S. 179 ; Eckerlein, 
Zischr. f. Geburtsh. u. Gyndk., Stuttgart, 1890, Bd. xix. S. 120. 

3 Med.-Chir. Trans., London, vol. xxix. p. 137 ; art. ‘‘ Thorax,” Todd’s ‘‘ Cyclopedia of 
Anat. and Physiol.,”’ vol. iv. p. 1085. 

4 Geppert and Zuntz, Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xlii. S. 189. 

° Result of a few observations by Pembrey and Reynolds. 


748 CHEMISTRY OF RESPIRATION. 


Temperature. — The frequency of respiration is greatly increased 
when the temperature of the body is raised above the normal by 
exposure to excessive heat, or by disease; this is especially marked in 
the dog, for thereby a much greater loss of heat by evaporation of water 
from the respiratory tract is effected. Richet has shown that this rapid 
breathing plays an essential part in the regulation of temperature in 
the dog.t 

The volume of inspiration and expiration — Jidal air. — The 
earliest determinations of the volume of an ordinary inspiration in 
man appear to have been made by Borelli? and by Jurin;® the latter 
estimated the amount at 656 e.c., or 40 cubic inches. Since that time 
numerous determinations have been made with different methods. The 
following are some of the results:—230 cc.,4 656 @c.5 574 «2.87 
492 «.c.,8 278 ae.,9 328 ac. 278 ac," 197 «c.,2 270 ce 

The causes of these variations are due to differences in the capacity 
of the chest of the different subjects of experiment, to individual 
differences in the breathing, and to imperfections in the methods 
employed. Vierordt!* has collected the results of the older observers, 
and finds as the minimal capacity of a single inspiration 53 ee. 
(Abilgaard), as the maximal 792 cc. (Senebier). From his own 
numerous determinations Vierordt! obtained 446 cc. as the mean 
volume of each inspiration, with a frequency of 11-9 per minute, 
whereas Speck 1° with a frequency of 63 respirations per minute found 
a volume of 1195-1051 ¢.c. for each inspiration. 

Hutchinson has collected the results of different observers, who 
found for the tidal air volumes varying from 49 to 1640 ¢.c.; he himself 
made eighty determinations on different men, and obtained 114-196 ce. 
during rest, and 262-360 c.c. during exercise; in one case the tidal air 
was as high as 1262 c.c. . 

Marcet '$ found, as the result of 210 experiments upon two men, a 
mean of 250 cc. for the tidal air, when the rate of respiration was 
16 per minute. 

The discrepancy in the results given above is natural; the cases are 
not comparable as regards the height, weight, age, sex, and development 
of the different subjects of experiment. It is useless, therefore, to 
attempt to give any figure which shall represent a true average, and it 


1 See ‘‘ Animal Heat,” this Text-book, vol. i. p. 856; Mathieu and Urbain, Compt. rend. 
Acad. d. sc., Paris, 1872, tome Ixxiy. p. 190. 

= *“De Motu Animalium,” p. 2, prop. 81. 

* Phil. Trans., London, 1717-19, vol. xxx. pp. 757, 758. 

* Goodwyn, ‘‘Connection of Life with Respiration,” London, 1788, p. 28. 

* Menzies, “On Respiration,” Edinburgh, 1796, p. 18. 

° Richerand, ‘‘ Physiology,” trans. by De Lys, p. 206. 

‘ Fontana, Phil. Trans., London, 1779, vol. lxix. p. 849. 

® Dalton, Mem. Lit. and Phil. Soc. Manchester, Sér. 2, vol. ii. p. 26. 

9 H. Davy, ‘‘ Researches,” p. 433. 

*° Jurine, ‘‘ Encyc. Metropol.,” art. ‘‘ Medicine,” vol. i. p. 494. 

1! Kite, ‘‘ Essays,” London, 1795, p. 47. 

12 Abernethy, ‘‘ Essays,” 1798, p. 142. 

8 Allen and Pepys, Phil. Trans., London, 1808, p- 256. 

4 Wagner’s ‘‘ Handwérterbuch,” Bad. ii. S. 836. 

19 <« Physiol. d. Athmens,” Karlsruhe, 1845, S. 255. 

16 “Untersuch. ueber Sauerstoffverbrauch u. Kohlensaéureausathmung des Menschen,” 
Cassel, 1871, S. 31; Arch. f. exper. Path. u. Pharmakol., Leipzig, Bd. xii. S. 19. 

aorege “Thorax,” Todd’s ‘‘Cyclopedia of Anatomy and Physiology,” vol. iy. 
p. 1067. 

#8 “Proc. Physiol. Soc.,” Journ. Physiol., Cambridge and London, 1897, vol. xxi. 


VOLUME OF INSPIRATION AND EXPIRATION. 749 


is much more useful to recognise that the tidal air varies considerably 
in different individuals, according to the rate and depth of breathing. 

The complemental air is the term given to the extra volume of air 
which can be taken into the lungs by the deepest possible inspiration. 
Its average value for an adult is said to be 1500 ce. H. Davy gives 
1951 «.c.,! Kite 32802 and Hutchinson 1722-1804 c.c.? 

The reserve or supplemental air is the volume of air which can be 
expelled after an ordinary expiration by a forcible and deep expiration. 
This is, according to Bostock’s * determinations, 2624 c.c. (160 cub. in.), 
while J. Bell® gives 1148 ec. (70 cub. in.), H. Davy, 1263 cc. (77 cub. 
in.), Hutchinson,® 1148-1804 e.c. (70-110 cub. in.), and Vierordt, 1226 c.c. 

The residual air is the air which remains in the lungs after the 
most forcible expiration; it cannot be driven out of the lungs during 
life. The methods’ employed to determine this volume of air are of 
two kinds, those for observations on the dead, and those for observations 
upon the living body. In the first case, the thorax of the corpse is 
forcibly placed in the position of a deep expiration, and then the air in 
the lungs is measured. For the determination of the residual air of the 
living subject, H. Davy® introduced an ingenious method; he found 
by experiment that hydrogen underwent no appreciable change in the 
lungs, and that it quickly diffused throughout the residual air; he 
therefore respired a quantity of this gas in a gasometer, and then made 
a forced expiration, the air of which was analysed. From the quantity 
of hydrogen left in the lungs, Davy calculated the total quantity of air 
in the thorax at the end of the forced expiration, and found it to be 
672 cc. (41 cub. in.). This method has been used by Gréhant,? and in 
a modified form by Hermann? and Berenstein." Several factors have 
to be taken into account, such as the absorption of hydrogen by the 
blood,!? and its diffusion in the residual air. 


Another but less reliable method is Pfliiger’s !® pneumonometer. The subject 
of the experiment, placed in a special chamber, keeps the chest, as far as 
possible, in the-position of a forced expiration, the pressure outside the body 
is then lowered by a known amount, and the lungs passively give off a certain 
quantity of air; this volume is measured, and from it and the alteration in 
pressure the residual air is calculated. The difficulty is to keep the chest in 
one position during the experiment. 


The results obtained by different observers are given in the follow- 
ing table : 4— 


1 “Chem. and Phil. Remarks,” p. 410. 

2 <‘Hssays and Observations, Physical and Medical,” 1795, p. 47. 

3 Article ‘‘Thorax,” Todd’s ‘‘ Cyclopedia of Anatomy and Physiology,” vol. iv. p. 1067. 

4“ An Elementary System of Physiology,” London, 2nd edition, 1828, vol. ii. p. 25. 

>“ Anatomy,” vol. i. p. 193. 

6 “Physiologie des Athmens,” Karlsruhe, 1845. 

7 For further details of different methods, see Jacobson, ‘‘Beitrage zur Frage nach dem 
Beitr. der Residualluft,” Diss., Konigsberg, 1887; and Berenstein, ‘‘ Hin Beitr. z. Bestim- 
mung der Residualluft,” Diss., Dorpat, 1891. 

8 “* Researches concerning Nitrous Oxide,” London, 1800, p. 399. 

9 Compt. rend. Acad. d. sc., Paris, 1862, tome lv. p. 279 ; Journ. de Vanat. et physiol. 
etc., Paris, 1864, tome i. p. 523. 

0  Tehrbuch der Physiol.,” Berlin, 1896, Aufl. 11, S, 126. 

1 Arch. f. d. ges. Physiol., Bonn, 1891, Bd. 1. 8. 363. 

12 Zuntz, Hermann’s ‘‘ Handbuch,” Bd. iv., Th. 2, S. 102. 

B Arch. f. d. ges. Physiol., Bonn, 1882, Bd. xxix. 8. 244, 

14 For some other results, see Hutchinson, Joc. cit. 


15e 


CHEMISTRY OF RESPIRATION. 


Volume of 
Residual Air 
in C.c. 


Method. 


for) 
=I 
bho 
i 


a 
for) 
Ss 
=} 


Zoi aa. | 
640 min. + 
981 mean 


440 min. 


796 mean 


= 


J 
1,250 max. | 
J 


526 max. | 
347 min. 
478 mean | 


| 


On corpse. 


On living subject. 


On corpse. 


On living subject. 


On nine corpses. 


On living subjects, 
sixteen males. 


On living subjects, 
three females. 


Observer. 


Remarks. 


Goodwyn.} 

H. Davy.? 

Allen and Pepys.’ 
Hutchinson. 
Neupauer.? 


Waldenburg.* 


| Gad.§ 

l Phiicer 9 

1 Pfliiger 
Kochs."° 

|f Hermann and 

|\ Jacobson. 

| Hermann and 

|\. Berenstein.!? 


{ Hermann and 
|\. Berenstein.? 


Mean of seven experi- 
ments. 


On one subject ; hydro- 
gen method used. 


Method defective,  re- 
sults too high.® 
| Method defective, re- 


sults too high.® 


Pneumonometer used. 


Hydrogen method used. 


Vital capacity is the term given by Hutchinson to the volume 
of air which can be expelled from the thorax by the most forcible 


expiration, following the deepest possible inspiration. 


The different 


values assigned to this volume of air are shown in the following 


fables —— 


1 «Connexion of Life with Respiration,” London, 1788, p. 25. 


9 


3 Phil. Trans., London, 1809, pp. 404, 410, 428. 
4 Article ‘“‘Thorax,” Todd’s ‘‘ Cyclopedia of Anatomy and Physiology,” vol. iv. p. 


1066. 


2 «Researches concerning Nitrous Oxide,” London, 1800, p. 399. 


5 Deutsches Arch. f. klin. Med., Leipzig, 1879, Bd. xxiii. S. 481. 


6 Zuntz, Hermann’s ‘‘ Handbuch,” Bd. iv. Th. 2, S. 103. 


7 Ztschr. f. klin. Med., Berlin, 1879, Bd. i. S. 27. 
8 Tagebl. d. 54 Versamml. deutsch. Naturf. u. Aerzte in Salzburg, 1881, 8. 117. 


® Arch. f. d. ges. Physiol., Bonn, 1882, Bd. xxix. S. 244. 


0 Zischr. f. klin. Med., Berlin, 1884, Bd. vii. S. 487. 
1 Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xliii. S. 236, 440. 
12 Jbid., 1891, Bd. 1. S. 363. 


13 See also Julius Jeffreys, 


ee 4 


taties of the Human Chest,” 1843; Jackson, 4m. Med. 


Examiner, 1851, p. 51; Radelyffe Hall, Trans. Prov. Med. and Surg. Assoc., London, 


1851. 


VOLUME OF INSPIRATION AND EXPIRATION. 751 


| 
ViTAL CAPACITY. | 
Observer. | Remarks. 
In Cubic In Cubic 
Centimetres. Inches. | 
3608 220 Jurin.! 
3608 220 Stephen Hales.* 
3493 213 H. Davy.? 
3058 186°5 Thomson.? . Mean of twelve 
experiments. 
3280 200 Goodwyn.? 50 
3280 200 Menzies.® 3 
4920 18007 pif: Kite.” 
3558 217 Mean | 
-| Thackrah.® 
4838 295 Max. | 
3558 217 Hutchinson. ? Mean for 1923 
Men. | 
3700 226 Hermann and Mean forsixteen | 
Berenstein. 2 Men. 


From numerous observations upon men, Hutchinson found that the vital 
capacity was influenced by the height, weight, and age of the subjects. The 
following table shows the progression of the vital capacity with the stature! :— 


j 
| 


| Cubic In. Cubic In. 
aan 175-0 176°0 
ae 1885 | 191-0 
ae 5 206-0 207-0 
ah ES | 299-0 228-0 
Seles 937-5 | 241-0 
Hheees 254°5 | 258-0 
Mean ‘of all J Migaag = = peitaiz-on 
heights (3509 c.c.) | (3558 c.z.) 


1 Phil. Trans., London, vol. xxx. p. 757. 

“* Statical Essays,’’ 2nd ed., London, 1731, vol. i. p. 243. 

“¢Chem. and Phil. Remarks,” p. 419. 

‘* Chemistry of Animal Bodies,” 1843, p. 610. 

“¢ Connexion of Life with Respiration,” London, 1788. 

“On Respiration,” Edinburgh, 1796. 

‘‘ Essays and Observations, Physical and Medical,” 1795, p. 48. 

8 «On the Effects of Arts, Trades, etc., upon Health,” London, 1831, p. 21. 
® Loc. cit. W Arch. f. d. ges. Physiol., Bonn, 1891, Bd. 1. S. 363. 
11] Foot = 304'8 mm.; 1 inch = 25°4 mm.; 1 cubic inch = 16°4 c.c. 


a om © bo 


i 


752 CHEMISTRV OF RESPIRATION. 


There is an irregular increase of the vital capacity with weight, and as 
regards age there is an increase from 15 to 35 years, and then a decrease 


Kw 
at 


Fre. 68.—Hutchinson’s spirometer. 


from 35 to 65 years, even when height is 
taken into consideration. When a man is 
standing, his vital capacity is 260 cub. in. ; 
in sitting erect, recumbent, and prone posi- 
tions, it 1s 255, 230, and 220 cub. in. 
respectively. 

On the opposite page the average 
amounts of complemental, tidal, reserve, 
and residual air are given, but it is 
necessary to point out again that they are 
only approximate values. The several 
volumes have already been shown tovary 
considerably in different individuals. 


Hermann! subdivides the residual air 
into collapse air, the quantity driven out of 
the lungs when the thorax is opened ; and 
the minimal air, the quantity which re- 
mains in the collapsed lungs. 

In newly-born children the volume of 
each inspiration in quiet breathing is 35 ¢.c., 
but during screaming it is raised to 61 ¢.c.; 
the vital capacity is about 120 cc. The 
volume of the lungs of four children born 
dead at full term was 40, 55, 55, and 60 c.c. 
respectively, and when blown out they con- 
tained 25, 30, 50, and 90 c.c. of air respect- 
ively.2 For the first few days of life the 
lungs completely fill the opened thorax ; 
there is no collapse air; the residual air is 
the minimal air. The lungs during each 
expiration become almost free from air, and 
the ventilation is very great, the renewal 
of air being almost perfect.° 

For the determination of the volumes 
of air present in the lungs under different 
conditions, Hutchinson used a_ special 
meter, which he termed a spirometer. The 
construction of this apparatus is shown in 
Fig. 68.4 

Since that time many simpler and 
improved forms of spirometer have been 
introduced.® The most important precau- 
tion is to reduce the resistance of the meter 
as much as possible, otherwise the depth 
and frequency of respiration become ab- 
normal. 


1“ Tehrbuch der Physiol.,’’ Berlin, 1896, Aufl. 11, S. 126. 
* Eckerlein, Ztschr. 7. Geburtsh. u. Gynék., Stuttgart, 1890, Bd. xix. 8. 120. 


° Hermann, doc. cit., S. 127. 


4 For further details, see Hutchinson, article ‘‘ Thorax,” Todd’s ‘‘ Cyclopedia of 
Anatomy and Physiology,” vol. iv. p. 1069. 

> Fleischl von Marxow, Centralbl. f. Physiol., Leipzig u. Wien, 1888, S. 39; Clar, 
Wien. klin. Wehnschr., 1889, No. 18 ; Marcet, ‘‘ Proc. Physiol. Soc.” Jowrn. Physiol., Cam- 
bridge and London, 1897, vol. xxi. ; Hanriot and Richet, Compt. rend. Soc. de biol., Paris, 


1887, p. 405. 


RATE OF RESPIRATION IN DIFFERENT ANIMALS. 753 
| 

| Cubic Cubic 

| Centimetres. | Inches. 

| 

a 

Complemental air . 1700) Vital 104) Vital 
Tidal air 300 ; capacity, 18 } capacity, 
Reserve or supplemental air | 1500 3500. 91 213. 
Residual air . : | 1000 61 


Hyperpnea, dyspnea, asphyxia, apnea, and Cheyne-Stokes’ respira- 
tion.—These different conditions are considered elsewhere in this work.! 
The rate of respiration in different animals.—Numerous observa- 
tions upon the rapidity of the respiratory movements in different animals were 
made by Paul Bert,? and the following table gives results obtained chiefly by 

’ him :— 


Number of 
Animal. Respirations Remarks, Observer. 
| per Minute. 
MamMALs— 
Monkey 19 Quiet Paul Bert. | 
Tiger 6 3) 93 
Lion 10 FF me 
Cat 24 By 5 
Dog 15 se a 
Ox 30 3 Robertson. * 
Rabbit . F 55 | oe Paul Bert. 
Rat, black and hits 210 a oe 
Rhinoceros 6 | Drowsy as 
Horse 10-12 =| Quiet. ie 
Brrps— 
Condor ; 3 : : 6 a: a 
Pelican ‘ : 3 : 4 9 8 
Cock 12 | Lying down. = 
Dove . 30 | Quiet. e 
House-sparrow 90 oa 53 
Canary 100 » , 
REPTILES— 
Rattle-snake . 2 é 3 5 ot 33 
Lizard . ; : : : 12 %> > 
FIsHES— 
Skate (Raia ae 51 " Lafont. 
Dogfish 40 ” or) 
Perch 30 - Paul Bert. 
Sole 34 +9 Lafont. 
Conger-eel 10 Quiet; length of Paul Bert. 
animal, 1 metre. 
5 25 | Quiet; length of 5 
animal, 50cm. | 
CrusTACEANS— 
King-crab (Limulus) 12 Moving. a4 
MoLiuscs— 
Poulp . 28 Quiet. 33 
Cuttlefish 45 oy Lafont. 
Squid Paul Bert. 


65 % 


1 This article, pp. 743, 765; also ‘‘ Mechanism of Respiration,” this Text-book, vol. ii. 

2 «*Tecons sur la physiol. comp. de la respiration,” Paris, 1870, p. 393. 

3 Veterinary Journal, London, 1885, vol. xx. p. 311. The rate of respiration in 250 
animals varied from 11 to 106 per minute. 

4 Quoted by Paul Bert, Zoe. cit. 


VOL. 1.—48 


754 CHEMISTRY OF RESPIRATION. 


The general conclusion to be drawn from these and other similar data is 
that the larger animals respire more slowly than the smaller animals of a 
similar class. It has been shown that a similar difference obtains in the out- 
put of carbon dioxide and the intake of oxygen. 

The alveolar surface of the human lungs.—The volume of the lungs 
in the mean phase of respiration is about 3500 c.c.; the diameter of a single 
alveolus is about 0-2 mm., its volume 0:004 c.mm., and its surface 0°126 s.mm. 
In order to contain the air in the lungs, there must be 725 millions of alveoli, 
with a surface of about 90 sq. metres.! The above calculation is the one given 
by Zuntz.? 


The changes in the composition of the air during respiration.— 
The fresh air taken into the lungs during respiration has the following 
composition, when it is dry and measured at 0° and 760 mm. pressure, 
20:96 volumes per cent. oxygen, 79°02 nitrogen, and about 0:03 carbon 
dioxide, or by weight per cent., 25:015 oxygen, and 76:985 nitrogen. 
Under ordinary conditions, the air e¢ontains a quantity of aqueous 
vapour, which is lable to considerable variations according to the 
temperature and other atmospheric conditions; the carbon dioxide, 
moreover, may in badly-ventilated rooms rise considerably above the 
amount just given. 

The inspired air is warmed and moistened in passing through the 
nose, pharynx, trachea, and bronchi, and rapidly mixes and diffuses with 
the air retained in the alveoli of the lungs. The passage of the air 
through the nose alone raises the temperature of the air considerably ; 
thus Bloch 4 found that, when the temperature of the external air was 
--8°, -0°°5 to 3°°5, 12° to 16° and 18°, that of the air entering the pharynx 
from the nose was respectively 24°5, 26°, 30°, and 31°. With a 
moderate external temperature the air becomes about one-third saturated 
with moisture during its passage through the nasal cavity. The rapidity 
of the processes of mixture and diffusion will vary according to the 
frequency and depth of breathing and the capacity of the lungs. The 
air expired will likewise vary in composition, and under normal condi- 
tions will never represent the alveolar air. 

The expired air—The earliest determinations of the composition of 
the expired air of man were made by Menzies,> Lavoisier and Seguin,° 
H. Davy,’ Allen and Pepys,’ and Prout.? The following table gives the 
more exact results of recent investigations, but at the same time it is 
important to remember that it is impossible to give figures which shall 
exactly represent the average composition of the expired air; the 
percentage of oxygen and of carbon dioxide varies according to the 
frequency and depth of breathing, and is influenced by various condi- 
tions which affect the metabolism of the body, such as muscular 
activity, temperature, and food. For these reasons the respiratory ex- 
change of an animal should be estimated by the direct determination 
of the intake of oxygen and the output of carbon dioxide and water in 

1] mm. = 0:03937 in., and 1 metre = 3937079 in. 

2 Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xlii. 8. 410. 


3 This includes a small quantity of argon, but it appears to have no physiological 
importance. 
4 Zischr. f. Ohrenh., Wiesbaden, Bd. xviii. S. 215, 354. 
5 «Hssay on Respiration,” Edinburgh, 1796, p. 50. 
6 Ann. de chim., Paris, 1814, tome xci. p. 318. 
7 “ Researches,” London, 1808, p. 331. 
8 Phil. Trans., London, 1808, 1809. 
® Ann. Phil., London, 1813, vol. ii. p. 328. 


COMPOSITION OF THE AIR DURING RESPIRATION. 755 


a given time, not by a calculation based upon the alteration in the com- 
position of the air of several expirations, multiplied by the average 
quantity of expired air and the average number of respirations in a 
given time. 


P Percent- ; A | 
Volume of | Percentage | Quantity | age of Quantity 
secre ee of Oxygen — of Carbon | 
Breathing. fe pee os Emad | renee ana Dioxide Dis Observer. 
= rad (per ps aa charged (per 
Minute). Alr. Minute). | Se aes Minute). | 
| i | | 
| G:C. | Ge | al 
Normal 7,527 16°29 | 358 | 4°21 318 | 
Very shallow 5,833 16°50 330 4°63 269 Speck.! 
Very deep . 17,647 18°29 | 487 3°17 560 | 
Normal. Rest 6,158 17°00 240 3°56 218 | 
Work - 16,191 17°29 587 3°65 593 -Speck.? 
Hard work. 24,323 | 16°96 | 964 | 4:08 | 993 J 
Normal 4,644 16°16 222°9 4°36 | 202-7 \Linow 3 
Normal 3,419 16°96 136°8 3°44" J Oey 


| 117°6 
| 


Vierordt* concluded from his experiments that the percentage of 
carbon dioxide in the expired air diminished, but the total discharge 
increased when the respiration was voluntarily quickened, the depth of 
breathing remaining the same, 500 c.c.; similar effects were produced by 
breathing more deeply but with the same frequency. The drawback to 
these observations is that they were for periods only lasting two or 
three minutes, and thus they are no exact measure of changes of meta- 
bolism. Even the extended observations of Lossen and Berg have been 
the subject of much discussion and criticism between Pfliiger® and 
Voit. It is impossible here to go fully into the causes of some of the 
contradictory results, but Pfliiger appears to have shown that the 
variations in the breathing have no influence upon the respiratory 
metabolism beyond this, that when the respiratory muscles are more 
active, an extra amount of metabolism, due to this activity, will occur. 
Pfliiger takes the mean of the conflicting results and obtains the 
following suggestive figures: 


Carbon dioxide discharged in fifteen minutes — 


j [ecko sen ecaeivaer alc ee Nea 
| Lossen . | 7°96 grms. 6°63 grms. 
Berg TT 9°106 ,, 
| ieee Ta, 


| Mean. 7°836 ,, Mean. 7868 ,, | 


1 Arch. d. Ver. f. wissensch. Heilk., Leipzig, 1867, Bd. iii. S. 317. 
2 « Physiologie des menschlichen Athmens,” Leipzig, 1892; Arch. f. Physiol., Leipzig, 
1896, S. 465. 

3" Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xliii. S. 523, et seg. 

4 Hesse, Arch. f. Hyg., Mimcehen u. Leipzig, 1884, Bd. ii. S. 381; ‘‘ Physiol. d. 
Athmens,” Karlsruhe, 1845, S. 116, 134. 

> Arch. f. d. ges. Physiol., Bonn, 1877, Bd. xiv. S. 1, 630. 

6 Ztschr. f. Biol., Miinchen, 1878, Bd. xiy. S. 95. 


756 CHEMISTRY OF RESPIRATION. 


This conclusion is supported by the work of Pfliiger’s pupils, Finkler and 
Oertmann,! who found that artificial respiration and apnoea? produced no 
alteration in the absorption of oxygen by rabbits. The respiratory exchange 
is determined by the activity of the tissues, and not by the frequency of 
respiration, or the amount of oxygen contained in the blood. 


Other changes in the respired air.—It has been shown that in 
a mman at rest the air respired undergoes a reduction in oxygen to about 
16 per cent., and an increase in carbon dioxide to about 4 per cent.; m 
addition, the temperature of the inspired air is raised to that of the 
body, and this generally occurs before the air reaches the smaller 
bronchi. At this temperature the air is saturated with moisture, and 
shows when dried a slight reduction, about ;'5 in volume, when it is com- 
pared with the inspired air, and both are measured at 0° and 760 mm. 
This decrease in volume is due to the combination and retention of some 
of the oxygen in the tissues, to the oxidation of some substances which 
leave the body otherwise than by the lungs, and to the combination of 
oxygen with hydrogen to form water. The oxygen does not reappear 
entirely as oxygen in combination with carbon to form carbon dioxide ; 


this is shown by the respiratory quotient, Which in omnivorous and 
2 

carnivorous animals is about 0°8. The effect of diet and other con- 

ditions upon the respiratory quotient is considered elsewhere in this 

work, and it has been shown® that, under certain conditions, marsh- 

gas, hydrogen, and nitrogen may be discharged by the lungs. 


THE EFFECT OF RESPIRATION UPON THE BLOOD. 


Historical.—The discovery of Harvey that every portion of blood passes 
through the lungs during each complete circulation, confirmed the idea of the 
early physiologists, that respiration produced important changes in that fluid ; 
Harvey * himself thought that the blood discharged some noxious substances 
as well as aqueous vapour into the air of the lungs. 

In 1669, Lower ® observed, on opening the thorax of a living animal, and 
keeping up artificial respiration, that the change of colour from venous to 
arterial took place in the capillaries of the lungs; the blood in the right 
ventricle was dark, and if the artificial respiration ceased it passed through the 
lungs to the left ventricle without attaining an arterial hue; venous blood, 
when exposed to air outside the body, acquired an arterial colour. Mayow,’ 
even earlier than 1674, maintained that this change from venous to arterial 
colour was due to the absorption by the blood of the nitro-aerial gas (oxygen) 
from the air in the lungs, but his work was neglected and forgotten. 

About the year 1776, Priestley § made a series of experiments, in which he 
showed that dark blood clot became red more rapidly in oxygen than in air, 
but the red colour was reduced to purple when the clot was placed in nitrogen, 
hydrogen, or carbon dioxide ; these alterations in colour also took place when 
the blood clot was separated from the air by a piece of moistened bladder, or 
by a thin film of milk. These changes were supposed by Priestley to be 


1 Arch. f. d. ges. Physiol., Bonn, 1877, Bd. xiv. S. 88. See also Pfliiger, ibid., S. 9. 

? See also Hanriot and Richet, Compt. rend. Acad. d. sc., Paris, 1887, tome civ. p. 1327. 
3 This article, pp. 700, 729. 

4 “De Motu Cordis.” 

° For older theories see p. 692, and the references there given. 

6 « Tractatus de Corde,” Londini, 1669, pp. 175, 181. 

7 “Tractatus Primus,” Oxon., 1674, p. 148. 

8 Phil. Trans,, London, 1776, pt. 1, p. 226. 


GASES OF THE BLOOD. 757 


similar to those of combustion, but, biassed by his belief in an old theory, he 
concluded that the removal of “ phlogiston” turned venous into arterial blood, 
and for this purification respiration was necessary. For many years there 
were two hypotheses to account for the effect of respiration on the blood. 
According to the one, which originated apparently with Black,' and was 
accepted by Priestley, Lavoisier,? and Crawford,* the oxygen in the inspired air 
combined with the carbon in the venous blood of the lungs, and formed 
carbon dioxide, which was discharged; whereas, according to the other 
hypothesis, proposed by Le Grange,* the oxygen was absorbed by the blood, 
and, during the course of the so-called systemic circulation, combined with 
carbon to form carbon dioxide, which was liberated when the blood again 
reached the lungs and took up a fresh supply of oxygen. 

Notwithstanding the experiments of Spallanzani® and of Edwards,® 
which proved that snails, frogs, and kittens continued to give out carbon 
dioxide in an atmosphere of hydrogen, the view that oxidation took place 
in the blood was held until recent times, when the work of Pfliiger and 
his pupils showed conclusively that the tissues were the important seat of 
combustion. 

According to Bohr,’ the tissues of the lungs have a further function than 
that of simply absorbing and discharging gases; they are said to be able to 
form carbon dioxide from substances brought to them from other parts of the 
body. Thus Bohr and Henriques * found that the lungs supplied 68 per cent. 
of the respiratory metabolism. It must be pointed out that in many of the 
experiments upon which this conclusion is based, the operative procedure was 
exceedingly severe, and the condition had no approximation to the normal; 
further, the results are not supported, in fact are contradicted, by the 
numerous experiments on internal respiration. 


The effect of respiration upon the blood is best studied by a com- 
parison of the gases contained in venous blood taken from the right 
ventricle, and in arterial blood taken from the carotid artery. 


The gases of the blood.—Methods for the extraction and esti- 
mation of the gases of the blood.—Historical.—The first demonstration 
of the presence of gases in the blood was made by Boyle® in 1636; he 
showed that, when fresh defibrinated blood was exposed to the vacuum of 
an air-pump, gas was given off. These particles of gas Mayow,! in 1674, 
considered to be nitro-aerial gas, that is, oxygen. The next important observa- 
tion was that made by Priestley,!! who noticed that blood placed in an 
atmosphere of hydrogen or nitrogen gave off oxygen. Girtanner ? observed 
the same effect with nitrogen. In 1799, Humphry Davy! found that 
twelve volumes of arterial blood, when heated to 93°, gave off 1:1 volume of 
carbon dioxide, and 0-7 volume of oxygen. 

Nasse,'# in 1816, proved that blood gave up oxygen to an atmosphere of 


1 «* Tectures on Chemistry,” edit. by Robison, Edinburgh, 1808. 

2 Hist. Acad. roy. d. sc., Paris, 1777, 1789, 1790. 

3 “*Qn Animal Heat,” 2nd edition, 1788. 

4 Hassenfratz, Ann. de chim., Paris, 1791, tome ix. p. 275. 

> «“Mém. sur la respiration,” trad. par Senebier, 1803. 

6 «<T)e Vinfluence des agens physiques sur la vie,” Paris, 1824. 

7 Skandin. Arch. f. Physiol., Leipzig, 1891, Bd. ii. S. 236. 

8 Centralbl. f. Physiol., Leipzig u. Wien, 1892, S. 225; Compt. rend. Acad. d. sc., 
Paris, 1892, tome exiv. p. 1496. 

9 *« Nova experimenta pneumatica respirationem spectantia,” Geneve, 1636. 

10 “Tractatus quinque,” Oxonii, 1674. ‘‘ Opera omnia,’’ Hagae Com., 1681, p. 133. 

U Phil. Trans., London, 1776, pt. 1, p. 226. 

12 Hassenfratz, Ann. de chim., Paris, 1791, tome ix. p. 275. 

13 Ann. d. Phys. u. Chem., Leipzig, 1803, Bd. xii. 8. 574, 593. 

4 Deutsches Arch. f. d. Physiol., Halle, 1816, Bd. ii. 8S. 195, 435. 


758 CHEMISTRY OF RESPIRATION. 


hydrogen, or of carbon dioxide, and Vogel,! in 1814, and Collard de Martigny,” 
in 1830, obtained carbon dioxide, but no oxygen, from blood subjected to a 
vacuum. Notwithstanding these observations, the presence of gases in the 
blood was for a long time a subject of controversy. Many physiologists, 
among them Johannes Miiller,? Schroeder van der Kolk,* Gmelin,” Mit- 
scherlich,® and Tiedemann,? maintained that no gas existed in the blood, 
whereas Nasse,® Scudamore,’ Bischoff,s and Van Euschut® obtained from 
blood carbon dioxide, but no oxygen. John Davy was at first’? unable to 
extract any gas from 
blood, but during a 
further research he 
obtained carbon dioxide 
from both arterial and 
venous blood. 

More exact methods 
of observation were in- 
troduced in 1837 by 
Magnus,!? who adopted 
and improved, for the 
extraction of the gases, 
the use of a Torricellian 
vacuum, a method due 
originally to Collard de 
Martigny. The conclu- 
sions to which Magnus 
arrived were that blood 
contained 4-8 volumes 
per cent. carbon dioxide, 
1-3°5 volumes per cent. 
oxygen, and 05-2 
volumes per cent. nitro- 
gen, and that arterial 
blood contained more 
oxygen than did venous 

blood. Fernet,!* in 1857, 
& published the results of 
experiments in which he 


§ andaeean ei : had extracted the gases 
Fie. 69,—] liiger’s Pump; a, b ood bu bis} roth-cham ber; of the blood by the 
d, drying tube; e, mercurial gauge ; h, graduated tube it f t f 

for collection of gas; 7, m, n, and 0, bulbs and tubing Passage Of a stream 0 
containing mercury. hydrogen, and the aid 

of a vacuum. About 

the same time, Lothar Meyer ™ developed the method !° of heating the blood 
or other liquid for the extraction of its gases, and a still further advance was 


qe 


Ti | 
3 


1 Journ. f. Chem. u. Phys., Niirnberg, 1814, Bd. xi. S. 399. 

> Journ. de physiol. expér., Paris, 1830, tome x. p. 111. 

3 «* Handbuch d. Physiol.,” Bd. i, S. 315. 

4“ Tissertatio sistens sanguinis coagulantis historiam.” 

> Zischr. f. Physiol., 1833, Bd. v. S. 6. 

Tires (etre 

7 «« An Essay on the Blood,” London, 1824, 

8 «*Commentatio, etc.,” Heidelberg, 1837. 

® “De respirationis Chymismo,” Trajecti ad Rhenum, 1836, pp. 78, 84, 98, 115, 142. 
0 Phil. Trans., London, 1823, p. 516. 

11s Researches,” London, 1839, vol. ii. p. 156, et seq. 

2 Ann. d. Phys. u. Chem., Leipzig, 1837, Bd. xl]. 8. 583 ; 1845, Bd. Ixvi. 8. 177. 

8 Ann. d. sc. nat., Paris, 1857, Sér. 4, Zool., tome viii. p. 125. 

14 «Tie Gase des Blutes,” Gottingen, 1857 : Ztschr. f. rat. Med., N.F., Bd. viii. S. 256. 
9 Used originally by H. Davy, Bunsen, and Baumert. 


GASES OF THE BLOOD. 759 


made when Ludwig and Setschenow,! Pfliiger? and Helmholtz,’ constructed 
their mercurial gas-pumps, based upon the principle of the Torricellian vacuum. 

The mercurial gas-pump.—Numerous forms+ of this apparatus have been 
introduced, but here it is only necessary to mention Pfliiger’s pump, the 
modification of this made by Gréhant,® and the simple apparatus devised by 
Leonard Hill. The principle of the first is shown in the diagram on p. 758. 

Further details upon the construction and working of these pumps will 
be found in text-books of physiological chemistry.® 

In Leonard Hill’s? gas-pump, the chief advantages are simplicity, cheap- 
ness, and rapidity of action ; 
the working errors are under Cor 
1 per cent., and only small | 
quantities of blood are required. 
The construction of the pump 
is shown in Fig. 70, and 
the successive manipulations 
are as follows :—‘ A, blood- 
receiver (F) is affixed to the 
end of the tube FE, and the 
receiver is elevated into the 
position indicated by the dotted H 
outline. The reservoir (B) is ee 
then put in connection with ; i 
the tube (E) by means of the ee | : 
three-way tap (D), the reservoir Zs Ms CoN) rt 
(A) is raised above the pump, (ae) <<? 
and the whole system is filled - ‘an IS 
with mercury to the top of the \ rat 
blood-receiver (F). The screw- a | 
clip on the rubber tube at the tums 
upper end of F is then closed, 
and the reservoir (A) lowered 
until the blood-receiver is ex- 
hausted, except for 2 or 3 c.c. 
of mercury, which is purposely 
left within. The screw-clip on 
the lower end of F is next closed, 
and the _ blood-receiver now 
clipped at either end, exhausted, 
detached from tube E, and ( 
weighed. A sample of blood is | °° = === == —— 
then collected. The arterial or Fic. 70.—Leonard Hill’s Gas-Pump. 
venous cannula is filled with 
blood, and immediately afterwards pushed into the rubber tube at the 


1 Sitzungsb. d. k. Akad. d. Wissensch. Math-phys. Cl., Wien, 1899, Bd. xxxvi. 8. 293. 

2<<Untersuch. a. d. Bonner physiol. Lab.,” 1865, S. 188; Centralbl. f. d. med. 
Wissensch., Berlin, 1866, S. 305; Arch. f. d. ges. Physiol., Bonn, 1868, Bd. i. S. 61. 

3 See Zuntz, Hermann’s ‘‘ Handbuch,” Bd. iv. Th. 2, S. 27. 

44. Schmidt, Ber. d. k. siichs. Gesellsch. d. Wissensch. Math-phys. Cl., Leipzig, 1867, 
Bd. xix. S. 33 ; Hoppe-Seyler, ‘‘ Physiol. Chem.,” Berlin, 1879, Bd. iii. S. 491 ; Nawrocki, 
Stud. d. physiol. Inst. zw Breslau, Leipzig, Bd. ii. 8. 144 ; Busch, Arch. f. d. ges. Physiol., 
Bonn, 1869, Bd. ii. S. 445; Kossel and Raps, Arch. f. Physiol., Leipzig, 1893, S. 198. 

5 Paul Bert, ‘‘Lecons sur la physiol. comp. de la respiration,” Paris, 1870, p. 102 ; 
‘Ta pression barométrique,” Paris, 1878, p. 615. 

6 Halliburton, ‘‘Text-Book of Chemical Physiology and Pathology,” London, 1891, p. 
30; Hempel, ‘‘Gasanalytische Methoden ;” Gamgee, ‘Physiological Chemistry of the 
Animal Body,” vol. i. pp. 200-206. 

7 Journ. Physiol., Cambridge and London, 1894-5, vol. xvii. p. 353 5 Hill and Nabarro, 
ibid., 1895, vol. xviii. p. 218. 


760 CHEMISTRY OF RESPIRATION. 


end of the blood-receiver, as far as the closed screw-clip. Before the 
insertion of the cannula, the end of the rubber tube is compressed with 
the fingers to exclude the air within it. A sufficient quantity of blood 
is now withdrawn by opening at the same time the screw-clip and the 
clip placed on the blood vessel of the animal. The blood is defibrinated 
by shaking it with the mercury left within the blood-receiver for that 
purpose, and the latter is then again weighed. The weight of the sample 
of blood is then obtained. The blood-receiver is next affixed once more to the 
tube (E), in the dependent position shown in the figure, and the tube (E) is 
exhausted. Finally, the screw-clip between E and the blood-receiver is 
opened, and the gases are withdrawn and collected in the eudiometer. Since 
the blood-receiver hangs freely from the tube (E) by means of a piece of 
rubber tubing, it can be both immersed in warm water, and shaken to facilitate 
the complete escape of the gases. The bulbous form of the blood-receiver 
prevents the blood from frothing over into the pump; and if the action 
becomes too violent, it can be immediately allayed by pouring a few drops 
of warm water on to the tube (KE). The bubbles are thereby driven back into 
the receiver, and the pump is never fouled. The tap (D) is so manipulated 
that the gases only, and not the water which condenses in the reservoir (B), 
are driven over into the eudiometer. The water is returned back into the 
blood-receiver. Three or four exhaustions are sufficient to extract all the gases 
from about 10 grms. of blood.” 

Methods of gas analysis cannot be described here; it is only necessary to refer 
the reader to the works of Bunsen, Hempel, and others! upon this special subject. 

In the extraction of the gases of the blood methods are employed which 
favour the dissociation of those gases which are present in loose chemical 
combination, and also liberate the gases present in a state of simple solution. 
These conditions are fulfilled by exposure to a vacuum, by warming and 
agitating the blood. The addition of a weak acid favours the evolution of the 
carbon dioxide. The effect of these different procedures upon the dissociation 
of oxyhemoglobin will be considered later; here it-is only necessary to recall 
the fact that the coefficient of absorption of gases in fluids diminishes with an 
increase of temperature, and becomes nil when the boiling point of the fluid is 
reached. 

For the quantitative estimation of the oxygen contained in blood, Claude 
Bernard? introduced a method based upon the stronger affinity shown by 
carbon monoxide than by oxygen for hemoglobin. The blood is shaken with 
double its volume of carbon monoxide, which drives out the oxygen from its 
combination with hemoglobin. An analy sis of the gas collected shows the 
percentage of oxygen. Nawrocki® has made comparative analyses with this 
method and with the ordinary blood pump, and the results are practically the 
same. If, however, the blood is left in contact with the carbon monoxide for 
longer than twenty- four hours, some of the gas combines with oxygen to form 
carbon dioxide, and thus the amount of oxygen is diminished.‘ It is possible 
that the carbon dioxide formed in these cases is due to putrefaction. 


The differences in the gases of arterial and venous blood.— 
A comparative examination of the gases contained in arterial and venous 
blood is necessary for the estimation of the qualitative and quantitative 
changes which occur during external and internal respiration. 

The gases of arterial blood.—The chief results obtained by 

‘Bunsen, ‘‘Gasometrische Methoden,” 1857 ; ‘‘Gasometry,” Roscoe’s transl., London, 
1857; cf. also Gamgee, op. cit., pp. 206- 215; Hempel, ‘‘ Gasanalytische Methoden” 
Geppert, ‘* Die Gasanaly se,” 1885. 

* « Tecons sur les liquides de l'organisme,” Paris, 1859, tome i. p. 365; il. p. 427. 


3 Stud. d. Nees Inst. zu Breslau, Leipzig, Bd. ii. S. 144. 
4 Bernard, Joc. cit., Pokrowsky, Virchow’s Archiv, 1866, Bd. xxxvi. 8. 482. 


oo 


GASES OF ARTERIAL BLOOD. 761 


different observers upon various animals have been collected in tabular 
form by Zuntz, and are here reproduced with some additions :-— 


| 


Quantity of Gas in Percentage | 
of Volume of Blood, 
Measured at 0° and 760 Mm. | Observer and Number of 


=e Experiments. 
| Oxygen. Nitrogen. | Neel | | 

Dog . 2 | Mean | 22°6 ore: | 34°3 | Pfliiger,? twelve experiments, but | 
| only three determinations of | 
CO,. Rapid method employed. 
Mean 18:3 18 | 37:7 | Forty-four analyses of carotid | 

LUE - 7 | Max. 24°7 5°5 | 53°4 | blood by Setschenow, Scheeffer, 
| Min. 11°4 1-2 | 23°3. | Sczelkow, Nawrocki, Hirsch- 

mann, Sachs and Pfliiger. Col- 
lected by Pfliiger.* 

Dog . . | Mean 18-4 | 2:0 | 38:8 | Blood of femoral artery. Twenty- 
| : five analyses by Pfliiger,? two 
by Hirschmann. 

( | Mean 19-4 _ 40°4 | One hundred experiments by Paul 

Dog - + | Max. 26°4 | 50°8 Bert.+ 

(| Min. 14-4 33-0 
Dog . 4 or 17°58 | .... | 88°57 | Geppert and Zuntz.® 
( 15°4 WS 40°1 | Gréhant.® 
7 at RS 45°9° 
DoE. I | ibe | ace” oe ego 
2g NS 40-4 
( os | 17-3 ~. | 33°&...] Ewald. 
aa mI ee ey eae 32°4 
mee 3 15°8 35-1 
- f 15-7 26°35 | 
F | 

Dog | Mean | 18°25 37°64 | Hill and Nabarro,® average of 
| filty-two samples of arterial 
j blood. 

Cat. - | Mean 13:1 1°3 28°8 | P. Hering,® six experiments. The 
value of oxygen is too low, 
since phosphoric acid was 
added to the blood beforehand. 

Sheep . - | Mean 107 18 | 45:1 | Sezelkow.!° Two analyses. 
| | | 

Sheep . . |Mean | 12°8 oe be Three analyses by Preyer on 

venous blood shaken with air. 

Rabbit - | Mean 13°2 Dit 34:0 | Four analyses by Walter.” 

Rabbit : seu th MU, ae 37°34 | Geppert and Zuntz.” 

Man | | 21°6 15 | 40°3 | One analysis by Setschenow. 


1 Article in Hermann’s ‘‘ Handbuch,” Bd. iv. Th. 2, S. 35. 

2 Centralbl. f. d. med. Wissensch., Berlin, 1867, S. 722. 

3 Arch. f. d. ges. Physiol., Bonn, 1868, Bd. i. S. 274. 

4 “Ta pression barométrique,” Paris, 1878, p. 1030. 

5 Arch. f. d. ges. Physiol., Bonn, Bd. xlii. S. 189. 

6 Compt. rend. Soc. de biol., Paris, 1892, p. 163. 

7 Arch. f. d. ges. Physiol., Bonn, 1873, Bd. vii. S. 575. 

8 Journ. Physiol., Cambridge and London, 1895, vol. xviii. pp. 223, 224, 227. 

9**Untersuch. u. d. Zusammensetzung der Blutgase wihrend der Apnoe,’’ Diss., 
Dorpat, 1867, Mcissner’s Jahresh., 1867, S. 305. 

W Arch. f. Anat., Physiol. u. wissensch. Med., 1864, S. 516. 

1 Wien. med. Jahrb., 1865, S. 145. 

2 Arch. f. exper. Path. vu. Pharmakol., Leipzig, Bd. vii. S. 148. 

B Arch. f. d. ges. Physiol., Bonn, Bd. xlii. S. 189. 


762 CHEMISTRV OF RESPIRATION. 


The results of analyses of the gases in the blood of birds and of other 
animals are given by Zuntz.! 

Estor and Saint-Pierre? concluded, from a few analyses of arterial blood, 
that the amount of oxygen diminished in proportion to the distance of the 
artery from the heart; these results, however, have been shown by Paul Bert,* 
Hirschmann,‘ and Pfliiger ° to be erroneous. The blood in the smaller arteries 
contains less oxygen, but this is independent of the distance from the heart, 
and appears to be due to the smaller number of red corpuscles, and the 
lower specific gravity of the blood.® 

The results given in the above table show considerable differences in the 
percentage composition of the gases of arterial blood, even when the experi- 
ments have been made upon similar animals. The causes of these differences 
are partly due to variations in the gases in the blood, and partly to errors of 
analysis. In order to test these points, double analyses of portions of the same 
blood have been made by Preyer and Ludwig,’ Pfliiger,S and others.? The 
most important discovery in this connection is that made by Pfitiger;!° the 
ordinary methods for the extraction of the gases of the blood give results 
which for the oxygen are too low, for the carbon dioxide too high ; arterial 
blood, when removed from the body, and kept from contact with the air, 
rapidly becomes darker. Some of the oxygen appears to be used up by the 
corpuscles with the production of carbon dioxide. If the blood be received 
directly from the artery into a large vacuum, and the gases quickly extracted, 
then values are obtained which show a higher percentage of oxygen, and a 
lower percentage of carbon dioxide than those found by the ordinary slower 
methods. The normal amount of oxygen in the fresh arterial blood of the 
dog is about 22 per cent. The carbon dioxide naturally shows considerable 
variations, but the amount of nitrogen in the most exact determinations is 
fairly constant, about 1°8 per cent. 


The arterial blood is not quite saturated with oxygen, for by rapid 
artificial respiration in the living animal, or by shaking arterial blood 
with air, the amount can be raised above 23 volumes per cent.! Geppert 


and Zuntz found in the arterial blood of dogs a relative saturation with 
oxygen of 96-99 per cent. The quantity of carbon dioxide in arterial 
blood is only about one-fifth of the amount which can be held by the 
blood, for Paul Bert! found that dog’s blood could take up about 150 
volumes per cent. when shaken with pure carbon dioxide. The nitrogen 
is simply in solution and the blood appears to be saturated with that 
gas, for the ordinary pressure and temperature. 

The gases of venous blood.—On account of the differences in the 
metabolism of the different tissues of the body, the venous blood is liable 


1 Article in Hermann’s ‘‘ Handbuch,” Bd. iv. Th. 2, 8. 41. 

> Journ. de Vanat. et physiol. ete., Paris, 1865, tome ii. p. 302. 

® **Lecons sur la physiol. comp. de la respiration,” Paris, 1870, p. 118. 

4 Arch. f. Anat., Physiol. u. wissensch. Med., 1866, S. 502. 

> Arch. f. d. ges. Physiol., Bonn, 1868, Bd. i. S. 274. 

° Mathieu and Urbain, Arch. de physiol. norm. et path., Paris, 1871, tome iv.; Pfliger, 
Arch. f. d. ges. Physiol., Bonn, 1868, Bd. i. S. 75. 

7 Wien. med. Jahrb., 1865, Bd. xxi. S. 145. 

8 Arch. f. d. ges. Physiol., Bonn, 1868, Bd. i. S. 61. 

* Hammarsten, Ber. d. k. stichs. Geselisch. d. Wissensch. Math.-phys. Cl., Leipzig, 
1871, Bd. xxiii. S. 630; Afanassiew, ibid., 1872, Bd. xxiv. S. 256 ; Tschiriew, ibid., 1874, 
Bd. xxvi. S. 120. 

1 Centralbl. f. d. med. Wissensch., Berlin, 1867, S. 321, 722. 

I Setschenow, Sitzwngsb. d. k. Akad. d. Wissensch., Wien, Bd. xxxvi. S. 289 ; Pfliiger, 
Arch. f. d. ges. Physiol., Bonn, 1868, Bd. i. S. 70; Ewald, ibid., 1873, Bd. vii. S. 575. 

2 Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xlii. S. 242. 

“Ta pression barométrique,” Paris, 1878, p. 1038. 


GASES OF VENOUS BLOOD. 763 


to corresponding variations in its gaseous constituents. It is therefore 
only possible to give a mean value for the gases of the venous blood 
when the analyses are performed upon samples removed from the right 
ventricle ; this procedure can be carried out by passing a catheter from 
the right external jugular vein through the right auricle and into the 
right ventricle. The following table gives the results of the few experi- 
ments of this kind, together with the data of simultaneous analyses of 
the arterial blood :— 


| 
| 


VEROUS ee BiGir ARTERIAL BLOOD. 
ANIMAL. = —————— SSS Observer. 
a Nitro- | Carbon es Nitro- | Carbor 
OxsEan. ea | dioxide. SSEL Pa } digaide: 
Wor. S| AEROBIE A Dees elias 2°F | 39°5 Scheeffer ? 
(mean of five 
| experiments). 
| } 
_ 55 56-4 | 22-1 | 361 |) 
- Paul Bert. 
a | } 49-0 | 193 | ... | 38-7 |I 
1 117 | 36-5 | 17-3 (334 |) | 
|; Ewald.* 
ee eet . | 84:0 | 15-4 .. | 324 |] 
¥ 12°5 | 36-0 | 165°) 348 |) 
- Finkler.* 
1255 24-96 | 16°12 | 30-65 || 
| 
fe. | 9-9 | 5475 | 17-25 |... | 42-75 |) Mathieu and 
| | lr . : 
| 5-43 cae) peace cae | Urbain.® | 


The effect of different conditions on the gases of venous blood—It has 
already been mentioned that the venous blood is liable to marked 
differences in its gaseous contents, according to the condition of the 
organs from which the blood is received. 

The venous blood leaving a muscle varies according to the condition 
of the tissues®; when the muscle is actively contracting, the percentage 
of oxygen in the blood is much diminished, and the amount of carbon 
dioxide is increased, notwithstanding the increase in the volume and 
velocity of the circulating blood. The experiments of Bernard’ and 
Zuntz® show that, after section of the motor nerve, the absorption of 
oxygen and the production of carbon dioxide in the muscle are much 


1 Sitzungsb. d. k. Akad. d. Wissensch. Math.-naturw. Cl., Wien, 1860, Bd. xli. 
S. 589. 

2 «Ta pression barométrique,” Paris, 1878, p. 1038. 

3 Arch. f. d. ges. Physiol., Bonn, 1873, Bd. vii. S. 575. 

4 Thid., 1875, Bd. x. S. 368. 

> Compt. rend. Acad. d. sc., Paris, 1872, tome Ixxiv. p. 190. : 

6 Sezelkow, Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1862, Bd. xlv. S. 171; 
Mathieu and Urbain, Compt. rend. Acad. d. sc., Paris, 1872, tome Ixxiv. p. 190 ; Bernard, 
“‘Lecons sur la chaleur animale,” Paris, 1876, p. 147; Zuntz, Berl. klin. Wehnschr., 
1878, No. 10, S. 141; von Frey, Arch. f. Physiol., Leipzig, 1885, S. 533; Chauveau and 
Kaufmann, Compt. rend. Acad. d. sc., Paris, 1886, tome ciii. pp. 974, 1057, 1153 ; Hill and 
Nabarro, Journ. Physiol., Cambridge and London, 1895, vol. xviii. p. 218. 

7 Loc. cit. 8 Loc. cit. 


764 CHEMISTRY OF RESPIRATION. 


less than in the normal condition, the blood undergoing comparatively 
slight changes in its passage through the capillaries. 


The following are some of the results obtained by Zuntz :— 


PERCENTAGE VOLUME OF GASES 
uN BLoop, 
Buoop VESSEL. _ Remarks. 
Oxygen. Carbon dioxide. 
Femoral vein . : ‘ 1:2 36°32 Dog at rest. 
Carotid artery . : : 14°4 21°92 
In the muscles of right | 
limb were absorbed and > 13°20 14°40 
produced respectively 
Femoral vein . 3 i 2°85 33°16 After section of sciatic 
and crural nerves on 
Carotid artery . : : 13°30 23°06 the right side. 
In the muscles of right 
limb were absorbed and - 10°45 10°1 
produced respectively . J 


Calculated from these results, the respiratory exchange before the section 
of the nerves was 1°21 ¢c.c. oxygen and 1°32 e.c. carbon dioxide per minute ; 
after section of the nerves, 0°68 c.c. oxygen and 0°65 c.c. carbon dioxide. 


Chauveau and Kaufmann! estimated the gaseous exchange in the 
masticatory muscles of the horse, both when it was at rest, and when it 
was actively chewing. The following table gives their results, together 
with those of somewhat similar experiments made by Sczelkow,? Hill 
and Nabarro :*— 


DIFFERENCE BETWEEN THE VENOUS AND ARTERIAL BLOOD. 
OBSERVER. 
Rest. Activity. 
Carbon dioxide | + 6°71 +10°79 SERPS Y Ta: 
xo Sezelkow. 
Oxygen . .| -9 — 12°26 - 36°78 J 
Carbon dioxide | +8°7 + 10°20 ( + 30°60 Chauveau 
B= and Kauf- 
Oxygen . .|—11°4 — 13°65 | — 40°95 mann. 
Tonic Clonic. 
van BR | 7A =C A 
Carbon dioxide | +8°'76 |+13:90 | Pk) f +41° 70}+19°33 } | ae ee 99 Hill and 
Oxygen. . |- 12°92 |-13-75 | i} — 41-25 | —12: 63) 97 Sui ee 


In the above table the amounts found during activity are multiplied 


1 Compt. rend. Acad. d. sc., Paris, 1886, tome ciii. pp. 974, 1057, 1153, 
* Sitzungsb. d. k. Akad. d. ’ Wissensch. , Wien, 1862, Bd. xlv. 8. 171. 
3 Journ. Physiol., Cambridge and London, 1895, vol. xviii. p. 218. 


CONNECTION BETWEEN BLOOD AND ITS GASES. 765 


by three, in order that allowance may be made for the increased rate of 
flow in the blood of an active limb. 

As regards the velocity of the circulation, Finkler?! finds that the 

difference between the arterial and venous blood increases as the velocity 
- diminishes. This relationship is well shown by Bernard’s? observations 
upon the submaxillary gland. When the gland is at rest the venous blood 
is dark, but becomes almost arterial in colour when the gland becomes 
active and its blood vessels are dilated by stimulation of the chorda 
tympani. The difference between the arterial and venous blood is less 
marked, but the total absorption of oxygen and production of carbon 
dioxide are increased. 

In the last stage of asphyxia, the arterial blood contains only traces 
of oxygen. Thus Ludwig gives, as the result of six analyses made by 
Setschenow and Holmgren upon asphyxiated dogs, 0-4 volume per cent. 
oxygen, 3 per cent. nitrogen, and 54 per cent. carbon dioxide; and Zuntz # 
has collected the results of nineteen analyses made by different observers,° 
and obtains an average of 0°96 volume per cent. oxygen, 2°07 per cent. 
nitrogen, 49°53 per cent. carbon dioxide. These values Zuntz contrasts 
with those obtained from averages of seventy-one analyses made by 
Pfliiger and others upon normal arterial blood, namely, 183 volumes per 
cent. oxygen, 1°9 per cent. nitrogen, and 38:1 carbon dioxide; and he 
shows that the ratio between the increase of carbon dioxide and the loss 
of oxygen is 0°66 in asphyxia, as compared with 0°79 in the normal con- 
dition. This difference is to be explained by the retention of some carbon 
dioxide in the tissues, owing to the high tension of that gas in the blood. 

During apneea the arterial blood is almost saturated with oxygen, and 
contains about one-half its normal amount of carbon dioxide; the venous 
blood, on the other hand, contains less oxygen as well as less carbon 
dioxide than it does in the normal condition. These results confirm the 
work of Pfliiger,”? who found that during apnea the respiratory exchange 
was not greater or smaller than in the ordinary condition of respiration. 

The changes which the blood undergoes in passing through the brain 
are much less marked than those which occur during its passage through 
muscles. Even during marked activity the brain has a comparatively 
small respiratory exchange.’ 

The nature of the connection between the blood and its gases.— 
Oxygen.—Magnus® in 1836 concluded that the gases of the blood were 
simply dissolved in that fluid, notwithstanding the fact that his experi- 
ments showed that the quantity of oxygen in the blood was much greater 
than the amount which could be dissolved in an equal volume of water 
exposed to air. Justus Liebig,!° however, pointed out that Regnault and 
Reiset’s 1! experiments showed that animals absorbed the same amount of 
oxygen whether they breathed pure oxygen or air; he therefore urged 


1 Arch. f. d. ges. Physiol., Bonn, 1875, Bd. x. S. 368. 

2 “«Tiecons sur les liquides de l’organisme,” Paris, 1859, tome ii. p. 435; ‘‘ Lecons sur la 
chaleur animale,”’ Paris, 1876, p. 185. 

3 Wien. med. Jahrb., 1865, Bd. xxi. S. 145. 

4 Hermann’s ‘‘ Handbuch,” Bd. iv. Th. 2, S. 43. 5 See Zuntz, loc. cit. 

6 Ewald, Arch. f. d. ges. Physiol., Bonn, 1873, Bd. vii. S. 575. 

7 Ibid., 1868, Bd. i. S. 100. 

8 Hill and Nabarro, Journ. Physiol., Cambridge and London, 1895, vol. xviii. p. 218. 
See also ‘‘ Animal Heat,” this Text-book, vol. i. p. 808. 

9 Ann. d. Phys. u. Chem., Leipzig, 1837, Bd. xl. S. 583 ; 1845, Bd. Ixvi. S. 177. 

W Ann. d. Chem. u. Pharm., 1851, Bd. |xxix. S. 112. 

Ann. de chim. et phys., Paris, 1849, Sér. 3, tome xxvi. 


766 CHEMISTRY OF RESPIRATION. 


that the gases of the blood were present in a state of loose chemical 
combination with some unknown constituent of the blood, in a similar 
way to that in which carbon dioxide is combined in solutions of sodium 
phosphate. A few years later, Lothar Meyer! came to a similar con- 


clusion, for he found that the amount of oxygen retained in the blood ~ 


only varied slightly with alterations of pressure. About the same time 
Fernet? observed that the amount of oxygen chemically combined in 
blood saturated with air was about five times greater than the quantity 
which could be dissolved at the ordinary atmospheric pressure; this 
oxygen was, moreover, chiefly contained in the red corpuscles. 

A further proof of the chemical combination of oxygen was obtained 
when Bernard ? and Hoppe-Seyler? discovered that the oxygen of the 
blood could be displaced by an equal volume of carbon monoxide, a gas 
which formed a more stable combination with the blood. The most con- 
vincing proof, however, was furnished when Hoppe-Seyler succeeded in 
erystallising hemoglobin, and showed that it combined with oxygen, but 
yielded up the gas to a vacuum; he also showed that the hemoglobin, 
for so he named the pigment of the red corpuscles, had a definite spectrum. 
A year or two later, in 1864, Stokes® discovered that reducing sub- 
stances removed oxygen from the hemoglobin and effected a marked 
change in its colour and spectrum. . 

The physical and chemical properties of hemoglobin are described 
fully in another part ® of this work; here it is only necessary to discuss 
the part which the pigment plays in the processes of respiration. 

The coefficient of absorption of blood for oxygen is a little lower than 
that of water, for the presence of salts in solution diminishes the capacity 
of the liquid to absorb gases.7_ The following table shows the volume of 


OxyYGEN ABSORBED 
ACCORDING TO DIFFERENT OBSERVERS. 
TrEMPERATURE. 
Bunsen.$ Winkler.9 Hiifner.10 
0° 0°04114 0°04890 
Be 0°03628 0°04286 
10° 0°03250 0°03802 
15° 0:02989 0703415 4.8 
20° 0702838 0°03103 0°02844 
25° on 0702844 0°02745 
30° Raa 0°02616 0°02635 
40° 2: 0°02306 0°02447 
50° a3 0:02090 


1 “Die Gase des Blutes,” Diss., Gottingen, 1857 ; Ztschr. f. rat. Med., Bd. viii. 8. 256. 

2 Ann. d. sc. nat., Paris, 1857, Sér. 4, Zool., tome viii. p. 125; Journ. de physiol. 
expér., Paris, 1860, tome iil. 

3 <<Tecons sur les effets des substances toxiques et médicamenteuses,”’ Paris, 1857, p. 
184; ‘‘Lecons sur les liquides de l’organisme,” Paris, 1859, tome i. p. 365; tome li. p. 427. 

4 Virchow’s Archiv, Bd. xi. S. 288; Bd. xiii. S. 104. 

5 Proc. Roy. Soc. London, vol. xiii. p. 357. 

6 Article ‘‘ Hemoglobin,” this Text-book, vol. 1. 

7 Mackenzie, Ann. d. Phys. uw. Chem., Leipzig, 1876, Bd. i. S. 438 ; Setschenow, Atschr. 
f. physikal. Chem., Leipzig, 1889, Bd. iv. S. 117; Hiifner, Arch. f. Physiol., Leipzig, 
1894, S. 130; 1895, S. 209. 

8 Ann. d. Chem. u. Pharm., Bd. xciii. S. 1; ‘‘Gasometrische Methoden,” Braunschweig, 
1857, S. 136. 

9 Zischr. f. physikal. Chem., Leipzig, 1892, Bd. ix. S, 174. 

0 Ann. d. Phys. wu. Chem., Leipzig, 1876, Bd. i. S. 682; Arch. f. Physiol., Leipzig, 
1890, S. 27. 


CONNECTION BETWEEN BLOOD AND ITS GASES. 767 


oxygen, measured at 0° and 760 mm., which can be absorbed by one 
volume of water. 

Bohr? found that the absorption coefficient of oxygen in a 2 per 
cent. aqueous solution of hemoglobin at 15° was 0:02249, whereas that 
for pure water is, according to Winkler, 0:03415, or 50 per cent. greater 
at the same temperature. 

It has been shown that arterial blood with a temperature of 37° 
contains a large quantity of oxygen, about 22 volumes per cent., an 
amount which could not be present in simple solution. Further, when 
the red corpuscles are absent, as im plasma and serum, the amount of 
oxygen in the fluid is, according to Pfliiger,? only 0°26 vols. per cent. 

In the next place, different observers have shown that crystals of 
heemoglobin can absorb large quantities of oxygen. 


Condition of Hemoglobin. “Oana 760. Mm.). Observer. 
100 grms. moist crystals . : : : : 108°4 c.c. Hoppe-Seyler.? 
| 
= crystals dried with filter-paper . ‘ 4679) 5 4 | 
a crystals dried at 0° and powdered. BAC rk | _ | 
- oe ; : : 2 : : 156-65 ¢- Dybkowsky.* 
A ,, fromhorse . : : : 44°83- Strassburg.® 
S8529 33 
a Pe : : : ; é , L803 = Preyer.® 
. SLAs , f : : : : Vi 1s 34 
e a : : : : : P 128 ES Worm Miiller.? 
Pe af : ; : A ; E 159 33 Hiifner.§ 
| 
Mean of 10 determinations. 
= crystals dried at 0° and det daaie 
from ox-blood  . ; 134 Ad Hiifner.? 


The causes of these differences are various; the crystals of 
hemoglobin were prepared in different ways, and it is probable that 
in some cases methemoglobin or other products were formed; the 
amount of moisture varied, and the methods employed for the extraction 
of the oxygen were different. 

Bohr,!° however, would explain these differences in another manner, 
for he maintains that there are at least four different kinds of hemo- 
globin, a-, 8-, y-, and é-hemoglobin, which have the same spectrum, but 
combine with different amounts of oxygen, 0-4, 0°8, 1°7, and 27 ce. 


1 «Exp. Untersuch. u. d. Sauerstoffaufnahme des Blutfarbstoffes,” Copenhagen, 1885, 
S. 37. 

2 Arch. f. d. ges. Physiol., Bonn, 1868, Bd. 1. S. 73. 

° Virchows Archiv, Bd. xxix. s. 598 ; Med.-chem. Untersuch., 1867, Bd. ii. S. 191. 

+ Hoppe- aioe Med.-chem. Untersuch. , 1866, Bd. i. S. 117. 

5 Arch. f. d. ges. Physiol., Bonn, 1871, Bd. iv. S. 454. 

8 Centralbl. 2 d. med. Wissensch., Berlin, 1866, No, 21. 

7 Ber. d. k. stichs. Gesellsch. d. Wissensch., Leipzig, 1870, Bd. xxii. S. 351. 

8 Zischr. f. physiol. Chem., Strassburg, 1878, Bd. i. S. 317, 386. 

® Arch. f. Physiol., Leipzig, 1894, S. 130. 

” Skandin. Arch. f. Physiol., Leipzig, 1892, Bd. iii. S. 47, 69, 76, 101. 


768 CHEMISTRY OF RESPIRATION. 


of oxygen for 1 grm. of hemoglobin. The usual form of hemoglobin is 
y-hemoglobin; this, when dried, gives a crystalline powder, «-heemo- 
globin, which in turn yields, on solution in water, 6-hemoglobin. A 
solution of y-hemoglobin, when kept in a closed tube, is converted 
into 6-hemoglobin. These various kinds of hemoglobin have different 
“specific oxygen capacities,’ by which term Bohr designates the ratio 
between ‘the number of grammes of iron and the number of cubic 
centimetres of oxygen present in a given volume of blood, of blood 
corpuscles or solutions of hemoglobin, saturated with air at ordinary 
pressure and temperature. The red blood corpuscles are said to 
undergo alterations in their specific oxygen capacity during their 
passage through the circulation. 

These results and theories have been subjected to an experimental 
examination by Hiifner,) who maintains that in fresh, healthy ox-blood 
there is only one kind of hemoglobin, that the capacity of the fresh 
hemoglobin for carbon monoxide and for oxygen is the same, whether 
it be hemoglobin directly dissolved from red corpuscles or heemoglobin 
first crystallised and then dissolved in water. By experiment, Hiifner 
shows that 1 grm. of hemoglobin takes up 1°338 c.c. of carbon monoxide 
or oxygen measured at 0° and 760 mm. This is confirmed by the 
following facts. The capacity of hemoglobin to combine with oxygen 
appears to depend upon its iron, one atom of which holds two atoms of 
oxygen. The hemoglobin of ox-blood contains 0°336 per cent. of iron, 
and its molecular weight is 16,669; its capacity for carbon monoxide or 
oxygen, as calculated from its percentage of iron, is 1:34 cc. for 1 grm., 
a figure practically identical with that obtained by direct experiment.? 
This is probably also the case with hemoglobin obtained from the 
horse, dog, pig, rabbit, and fowl, for Bunge and others? have shown 
that the general percentage of iron is 0°335 per cent. Further, the 
amount of hemoglobin in human blood is about 14 per cent., and since 
1 grm. of hemoglobin can absorb about 1:34 ¢.c. of oxygen, it follows that 
the amount of oxygen combined in arterial blood should be about 20 
volumes per cent., and actual experiment shows that this is the case.* 

It is probable that some of Bohr’s results are due to mixtures of 
pure and partly decomposed hemoglobin, and that some of the hemo- 
globin may be in the form of methemoglobin. The same criticism 
may possibly apply to the results obtained by Haldane and Lorrain 
Smith.® 


The oxygen in the blood of invertebrates.—In many of the invertebrate 
animals, hemoglobin, hemocyanin, and other proteids, which can enter into 
loose combination with oxygen, are found and play a part in the process of 
respiration. It is impossible, however, in a few words, to do justice to this 
interesting portion of comparative physiology ; for further details, the article 
by Halliburton © on the blood of invertebrate animals should be consulted. 


1 Arch. f. Physiol., Leipzig, 1894, S. 130. 

*See also Hoppe-Seyler, Virchow’s Archiv, Bd. xxix. S. 598; Med.-chem. Untersuch., 
1867, Bd. ii. S. 191; Preyer, ‘‘De hemoglobino observationes et experimenta,” Bonne, 
1866, p. 19 ; Centralbl. f. d. med. Wissensch., Berlin, i866, No. 21. 

3 Jaquet, Ztschr. f. physiol. Chem., Strassburg, 1889, Bd. xiv. S. 289. 

4 See p. 761. 

> Journ. Physiol., Cambridge and London, 1894, vol. xvi. p. 468. 

6 ««'Text-Book of Chemical Physiology and Pathology,” London, 1891, pp. 316-330. Here 
numerous references to previous work on the subject will be found. Among subsequent 
papers may be mentioned those of Griffiths, Compt. rend. Acad. d. sc., Paris, 1892, 
tome cxv. pp. 259, 419, 474, 669, 738 ; exvi. p. 1206. 


CONNECTION BETWEEN BLOOD AND ITS GASES. 769 


Nitrogen.—The blood contains about 1°8 volumes per cent. of 
nitrogen, and this is present chiefly in a condition of solution. Thus 
Lothar Meyer! and others? have found that the absorption of nitrogen 
by defibrinated blood is proportional to the pressure. This, Paul Bert? 
showed, was also the case in living animals, but, owing to the want of 
perfect ventilation of the lungs, the increase did not exactly follow 
Dalton’s law. Thus— 


| F Percentage of . Percentage of 
Pressure in = a ; Pressure in zs ae 
Atmospheres. S a od hege Atmospheres. cies eT Dog's | 
1 2°2 5 6-0 
2 3°0 7 70 
| 3 lege HS 10 9-4 
| | 


The coeflicient of absorption of water for nitrogen is small, and the blood 
has even less power of absorption, for Fernet, Setschenow, Hiifner, and others + 
have shown that the presence of other substances in solution diminishes the 
capacity of water to absorb gases. The following table shows the coefficient 
of absorption of water for nitrogen at different temperatures :— 


} } | 
| | COEFFICIENT OF ABSORPTION. 


TEMPERATURE. 


Bunsen? Hiifner.6 Winkler.7 
i | =| 
0° 002035 u | _ 0-02848 
5° | 001794 ia 002081 
10° | 0°01607 re 0°01857 
| 15° 001478 = 001682 
| 20° 0-01403, | osbi40e  \ o setoreegooe 
| 25° | | 001857 901431 
30° | im | 001308 | 0-01340 
oF | | 0-@1289 | | 
40° | ovizio =| o-o1ss | 


1 “*T)ie Gase des Blutes,” Inaug. Diss., Gottingen, 1857, S. 56. 

2 Setschenow, Sitzungsh. d. k. Akad. d. Wissensch. Math.-naturw. Cl., Wien, Bd. xxxvi. 
S. 293. 

3 “Ta pression barométrique,” Paris, 1878, p. 661. 

4 Fernet, Ann. d. sc. nat., Paris, Sér. 4, ‘‘ Zool.,” tome viii. p. 125 ; Setschenow, Mém. 
Acad. imp. d. sc. de St. Pétersbourg, 1879, tome xxvi. p. 6; Ztschr. f. physikal. Chem., 
Leipzig, 1889, Bd. iv. S. 117; Hiifner, Arch. f. Physiol., Leipzig, 1894, S. 130; 1895, S. 
209; Mackenzie, Ann. d. Phys. u. Chem., Leipzig, 1876, Bd. i. S. 438; Bohr, ‘‘ Exper. 
Untersuch. u. d. Sauerstoffaufnahme des Blutfarbstoffes,” Copenhagen, 1885, S. 37. 

5 “ Gasometrische Methoden,” 1857, S. 136 (‘‘Gasometry,”’ Roscoe’s transl., London, 
1857). 

6 Ann. d. Phys. uw. Chem., Leipzig, 1877, Bd. i. 8S. 632; Arch. f. Physiol., Leipzig, 
1890, S. 27. 
7 Ztschr. f. physikal. Chem., Leipzig, 1892, Bd. ix, S. 173, 


VOL. I.— 49 


770 CHEMISTRY OF RESPIRATION. 


Further proofs that the nitrogen is simply in solution are afforded by 
two experiments made by Pfliiger. Blood subjected to the vacuum of a 
mercurial pump quickly gives off its nitr ogen; thus at 0° all the nitrogen, 
but less than half the oxygen and three- -quarters of the carbon dioxide, 
were given off in twenty hours! The blood of a dog which had pre- 
viously breathed for a few minutes a mixture containing only oxygen 
and carbon dioxide, yielded no nitrogen to a vacuum; that gas had 
rapidly diffused from the blood into the air of the lungs. 2 

Carbon dioxide.—The nature of the connection between the carbon 
dioxide and the blood, which contains it, is very difficult to follow, and 
has given rise to much discussion.? There is no single substance ‘with 
which the whole of the carbon dioxide is combined ; it is present both 
in the red corpuscles and plasma, and, after coagulation of the blood, 
in both the clot and serum. It will be well, therefore, to consider— 
(1) The amount of this gas, which may be in a state of simple solution 
in the blood and in serum; (2) the quantity in loose and firm chemical 
combination with substances in the corpuscles and in the plasma and 
serum of the blood. 

Carbon dioxide is much more soluble in water than oxygen and 
nitrogen. Plasma and serum are not able to retain in simple solution 
as much carbon dioxide as can a similar volume of pure water, for it 
has already been mentioned that the presence of indifferent substances 
in solution diminishes the capacity of the fluid to absorb gases. There 
are, however, exceptions* to this general rule, and it is therefore 
necessary to determine experimentally the absorption coefficient of 
carbon dioxide in blood before we conclude that it is less than in water. 
This experiment was made by Zuntz,> who neutralised the blood with 
phosphoric or oxalic acid in order to eliminate its chemical affinity, 
saturated it with earbon dioxide, and then determined the amount 
absorbed. He found that the coefficient of absorption for calves’ blood 
with a specific gravity of 1038 was 1°626, and that for sheep’s blood 
with a specific gravity of 1052 was 1:547 at 0°. 


gaat eine pect Tae CarBON Dr0xIDE IN Doa’s SERuM (0° and 760 Mm.). 
| | 
Percentage } 
s : Chemical 
Mm. mercury. of an Total. uantity Absorbed. | “Quantity in 
Atmosphere. Q | Combination. 
105°8 13°9 | 61:1 per cent. 20°7 per cent. 46°4 per cent. 
QF. . 99. . . 
351°4 46°2 } 22s Ac 68°8 an | Daud AS 
747°8 98°4 202°2 * 146°4 aA 55°8 


? Pfliiger, ‘‘ Die Kohlensiure des Blutes,”” Bonn, 1864, S. 12. 

2 Pfliiger, Arch. f. d. ges. Physiol., Bonn, 1868, Bd. i. S. 104. 

3 For further details see Zuntz, Hermann’s ‘‘ Handbuch,” Bd. iv. Th. 2, S. 64; 
Hammarsten, ‘‘ Lehrbuch der phy siologischen Chemie,” Wiesbaden, 1895, S. 535 ; Setsche- 
now, Mém. ‘Acad. imp. d. se. de St. Péersbourg, 1879, aoe XXvVi. p. 6; ; Zuntz, ** Beitr. 
7 Physiologie des Blutes,” Inaug. Diss., Bonn, 1868, S. 

+ Buchanan, Proc. Roy. Soc. London, 1874, No. Lb eps ane 
S - “Beitr. z. Physiol. des Blutes,” S. 39; Hermann’s ‘‘Handbuch,” Bd. iv. Th. 2, 

D 


CONNECTION BETWEEN BLOOD AND ITS GASES. 771 


Setschenow! calculated that serum held in simple solution 99 per 
cent. of the amount of carbon dioxide which distilled water would 
absorb under similar conditions, and that one-tenth of the total carbon 
dioxide in the serum of dog’s blood was in simple solution. The result 
of further experiments made by Zuntz? upon these points is shown in 
the table on p. 770. 

In the next place, it is necessary to consider the amount of carbon 
dioxide in loose and firm chemical combination with substances in the 
corpuscles, plasma and serum. Most of the gas is contained in the 
plasma or serum, for these fluids contain a larger quantity of carbon 
dioxide than that which can be obtained from an equal volume of blood. 
The greater quantity of the gas is in a state of loose chemical combination 
in the serum, for much of it can be extracted by the action of the 
vacuum of a blood-pump; the remainder, however, is in firm chemical 
combination, and is only set free in the pump by the addition of an 
acid. In this respect a marked contrast is observed between blood and 
serum, for a// the carbon dioxide can be extracted from the former by 
the action of the vacuum alone, the hemoglobin of the red corpuscles 
playing, apparently, the part of an acid 

The following table shows the amount of carbon dioxide in loose and 
firm chemical combination in serum :— 


CARBON DIoxIDE IN SERUM, 
(Volumes per cent.) 
CARBON DIOXIDE IN 
BLoop. OBSERVER. 
(Volumes per cent.) 
Extracted by In Firm Com- | Total in Com- 
Vacuum. bination. | bination. 
13°4 31°3 44-7 34°5 Scheefier.? 
| 
2151 21°9 43°0 35°0 Ac 
44°6 4-9 49°5 o Pfliiger.° 
35°2 9°3 44°5 be aa 
19°9 6°9 26°8 he Zuntz.°® 
22°0 12°4 34°4 | a An 
Di) 1355 36°0 oon o: 
26°9 17:0 43°9 as 99 


The differences in these results are due, as Zuntz’ has pointed out, 
to the powerful action of Pfliiger’s pump, and to the concentration of the 
serum during its exposure to the vacuum. The carbonates of the serum give 
off their gas more readily when the solution is concentrated ; this complication 


1 Loc. cit., Centraibl. f. d. med. Wissensch., Berlin, 1877, No. 35. 

* Hermann’s ‘‘ Handbuch,” Bd. iv. Th. 2, S. 68. 

3 Setschenow, Sitzwngsb. d. k. Akad. d. Wissensch., Wien, 1859,. Bd. xxxvi. S. 293 ; 
Pfliiger, ‘‘ Ueber die Kohlensaiure des Blutes,” Bonn, 1864, S. 5; Zuntz, Centra/bl. f. d. 
med. Wissensch., Berlin, 1867, S. 527. 

4 Sitzungsb. d. k. Akad. d. Wissensch. Math.-naturw. Ci., Wien, 1860, Bd. xli. S. 616. 

® ** Ueber die Kohlenséure des Blutes,” Bonn, 1864, S. 11. 

6 Centralbl. f. d. med. Wissensch., Berlin, 1867, S. 529; Hermann’s ‘‘ Handbuch,” 
Bd. iv. Th. 2, S. 45. 

7 Loc. cit. 


772 CHEMISTRY OF RESPIRATION. 


was avoided in the analyses made by Zuntz, by the addition of distilled water 
in sufficient quantity to maintain the concentration of the fluid at its original 
point. Preyer! found that the proportion of carbon dioxide in loose and in 
firm combination was as 2 to 3°5, 


The next question to discuss is the nature of the substances with 
which the carbon dioxide is combined. The facts already mentioned 
show that these substances are to be sought chiefly in the serum. In 
the first place, analyses of the ash of serum show that the most important 
constituents are the alkalies; thus, according to Bunge’s? experiments, 
the ash from 1000 gris. of dog’s serum contains 4341 grms. sodium, of 
which 3°463 grins. is sufficient to saturate the chlorine. The remainder, 
0-878 grms. sodium, can combine with 0°625 grms. carbon dioxide (516 
c.c. at 0° and 760 mm.) to form sodium carbonate, and, in addition, with 
another equal quantity to form sodium bicarbonate. Thus calculated, 
a litre of plasma could hold 632 cc. of carbon dioxide, or 63 volumes 
per cent. in chemical combination. This must be considered only as an 
approximate result, for the amount of sodium carbonate in serum cannot 
be accurately determined by an analysis of the ash or by titration, for 
the alkali is combined with other substances, especially with proteids.* 

The alkalies of the blood are the most important constituents for 
holding carbon dioxide in combination. Serum freed from gas can 
combine with as much carbon dioxide as is necessary to form bicarbonates 
with its alkalies; any reduction in the alkalinity of the blood is accom- 
panied by a decrease in carbon dioxide. Thus Walter* found only 
2 to 3 volumes per cent. of carbon dioxide in the blood of rabbits poisoned 
by hydrochloric acid; Geppert and Zuntz® observed that the alkalinity 
of the blood of rabbits was diminished by-the acid formed during tetanic 
muscular activity, and at the same time there was a decrease in the 
carbon dioxide of the blood. During diabetic coma the alkali of the blood 
appears to be in great part neutralised by combination with 8-oxybutyric 
acid;® and Minkowski? found only 3:3 volumes per cent. of carbon 
dioxide in the blood of a patient suffering from diabetic coma. 

Another substance with which the carbon dioxide is supposed to 
combine in serum is disodium hydrogen phosphate * (Na,HPO,), with the 
formation of sodium bicarbonate and sodium biphosphate. Thus— 


Na,HPO, + CO, + H,O = NaHCO, + NaH,PO,. 


Sertoli? and Mroczkowski® however, found that the quantity of 
phosphoric acid in the serum is so small that, if allowance be made for 
that contained in lecithin and nuclein, the amount is quite insufficient 


1 Sitzungsb. d. k. Akad. d. Wissensch. Math.-naturw. Cl., Wien, Bd. xlix. 8. Divs 

2 Ztschr. f. Biol., Miinchen, 1876, Bd. xii. S. 204; ‘‘ Lehrbuch der physiologischen 
und pathologischen Chemie,” Leipzig, 1889, S. 254. 

3 Hoppe-Seyler, ‘‘Physiol. Chem.,” Berlin, 1879, Bd. iii. S. 502; Sertoli, Med.- 
chem. Untersuch., Berlin, 1868, Heft 3, S. 350. 

4 Arch. f. exper. Path. u. Pharmakol., Leipzig, Bd. vii. 

> Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xlii. S. 189. See also this article, p. 714. 

6 Stadelmann, Arch. f. exper. Path. u. Pharmakol., Leipzig, Bd. vii. ; Minkowski, 
iis Bd. xviii. ; Mitth. a. d. med. Klin. zu Kénigsberg, Leipzig, 1888. 

Loc. cit. 

8 Fernet, Ann. d. sc. nat., Paris, Sér. 4, tome viii. p. 160 ; Heidenhain and L. Meyer, 
Stud. d. physiol. Inst. zu Breslau, Leipzig, 1863, Heft 2; Ann. d. Chem. u. Pharm., 
1862-68, Supp. Bd. ii. S. 157. 

® Hoppe-Seyler, Med.-chem. Untersuch., Berlin, 1868, Heft 3, S. 350. 

W Centralbl. f. d. med. Wissensch., Berlin, 1878, No. 20, S. 356. 


CAUSES OF THE EXCHANGE OF GASES. 773 


to play any important part in combining with carbon dioxide. Bunge,* on 
the other hand, maintains that in dog’s blood the quantity of phosphoric 
acid is sufficient, and that only a‘small quantity is combined with alkalies 
in the plasma; he agrees, however, with the previous observers, that the 
amount of phosphoric acid in the blood of the ox and the pig is very small. 

There is also evidence to show that the proteids, especially the 
globulin of serum, play some part in forming combinations with carbon 
dioxide. Setschenow? considered that the globulin formed a combina- 
tion with the carbon dioxide, whereas Sertoli held that the globulin 
acted as an acid, and in the serum was combined with an alkali. 

The blood corpuscles contain about one-third of the total carbon 
dioxide found in the blood. The gas is in loose chemical combination 
probably with the alkali of the phosphates, globulin, and hemoglobin 
of the corpuscles, and directly with the hemoglobin. Setschenow 
calculates that in 100 volumes of blood the red corpuscles contain 10 
volumes, and the white corpuscles 2°5 volumes of carbon dioxide. 

The experiments of Setschenow,* Zuntz,? Bohr? and Torup’ show 
that carbon dioxide combines with hemoglobin even in the absence of an 
alkali. A solution of pure crystallised hemoglobin absorbs more carbon 
dioxide than does an equal volume of water, and the amount of gas 
absorbed is relatively large for low pressures, but relatively small for 
high pressures. According to Bohr, 1 grm. of hemoglobin at 18-4, and 
under a pressure of 30 mm., combines with 2:4 c.c. of carbon dioxide ; 
the pigmented portion of the hemoglobin is supposed to combine with 
oxygen and the proteid portion with carbon dioxide. 

Further investigation, however, is necessary before it will be possible 
with any exactitude to decide the relative importance of the different 
combinations with the carbon dicxide of the blood. 

The causes of the exchange of gases between the air in the 
lungs and the blood.—The oxygen of the blood is derived from the air 
in the alveoli of the lungs: the carbon dioxide in the expired air comes 
from the pulmonary blood, and ultimately from the tissues of the body. 
The inspired air contains at 0° and 760 mm. 20°96 volumes per cent. 
of oxygen, the expired air about 16 per cent., and the tissues no free 
- oxygen; the carbon dioxide is 0:03 volumes per cent. in the inspired 
air, about 4 in the expired air, and in the tissues is being constantly 
produced. There would, therefore, appear to be sufficient causes, both 
physical and chemical, to determine the passage of the oxygen inwards 
and of the carbon dioxide outwards. 


OXYGEN, Alveolar air —-> Blood —-> Tissues. 
Carpon DioxipE, ‘Tissues —+» Blood —- Alveolar air. 


1 Ztschr. f. Biol., Miinchen, 1876, Bd. xii. S. 206; ‘‘ Lehrbuch der physiologischen und 
pathologischen Chemie,’ Leipzig, 1889, S. 256. 

2 Arch. f. d. ges. Physiol.. Bonn, 1874, Bd. viii. S. 1; Centralbl. f. d. med. Wissensch., 
Berlin, 1877, No. 25; 1879, No. 21; Ber. d. deutsch. chem. Gesellsch., Berlin, 1879, Bd. xii. 
S. 855; Mém. Acad. imp. d. sc. de St. Pétersbowrg, 1879, tome xxvi. No. 13. 

3 Alex. Schmidt, Ber. d. k. séichs. Gesellsch. d. Wissensch. Math.-phys. Cl., Leipzig, 
1867, Bd. xix. S. 30; Zuntz, Centralbl. f. d. med. Wissensch., Berlin, 1867, S. 529; Her- 
mann’s ‘“‘ Handbuch,” Bd. iv. Th. 2, S. 72 ; Fredericq, ‘‘ Recherches sur la constitution du 
plasma sanguin,” Gand, 1878, p. 49. 

4 Centralbl. f. d. med. Wissensch., Berlin, 1877. 

5 Hermann’s ‘‘ Handbuch,” Bd. iv. Th. 2, S. 76. 

6 Beitr. z. Physiol. Carl Ludwig z. s. 70 Geburtst., Leipzig, 1887, S. 164; Jahresb. 
ii. d. Fortschr. d. Thier-Chem., Wiesbaden, Bd. xvii. S. 115. 

7 Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, Bd. xvii. S. 115. 


774 CHEMISTRY OF RESPIRATION. 


The evidence, however, in support of this explanation must be 
examined, for of late it has been challenged, especially by Bohr.t In 
the first place, it is necessary to remember that the composition of the 
alveolar air is not represented by that of the air expired. The composi- 
tion of the inspired and of the expired air and the tension of their 
component gases can be readily determined. The tension of oxygen in 
the inspired air is 159 mm., under the mean pressure of an atmosphere, 
760 mm. It is difficult, however, to obtain with accuracy similar data 
for the air of the alveoli. From the numerous analyses of expired air 
in a man, it is possible to form only a rough estimate of the alveolar air ; 
it probably contains 5 to 6 per cent. of carbon dioxide, and 14 to 15 
per cent. of oxygen; and the tension of the former would be about 
36 mm., and of the latter about 114mm. Lowy? calculates that the 
tension of oxygen in the alveoli of the human lungs is from 12°6 to 13°5 
per cent. of an atmosphere, or about 99 mm. of mercury. 

In animals, direct determinations of the composition of the alveolar 
air of an occluded portion of the lungs have been made. For the 
collection of this air Pfliiger® constructed a special catheter (Fig. 71). 

if It consists of an 
sai ordinary fine elastic 
=f catheter, surrounded, 

except at its extrem- 
ities, by a tube with 
a rubber enlargement 
towards the free end 
of the catheter. The 
instrument is so small 
that, when introduced 
through the trachea 
into a bronchus of a 
dog, it causes no hind- 
rance to the free 
passage of air into the other parts of the lungs. The rubber enlarge- 
ment is now inflated, and shuts off a portion of the lungs, from which 
the alveolar air can be withdrawn through the inner tube of the lung 
catheter. In such experiments Wolffberg* and Nussbaum ® found 
that the alveolar air of a dog contained 3-5 per cent. of carbon dioxide, 
whereas the expired air yielded 2°8 volumes per cent. It is to be noted 
that this value for the alveolar air is higher than the normal, for the air 
in the alveoli was shut off from the tidal air, and, in fact, represents the 
air after an equilibrium had been established with the gases of the blood 
passing through that portion of the lung shut off by the catheter. 

In the next place, it is necessary to consider the tension of the 
oxygen and carbon dioxide present in the blood, and this involves a 
preliminary study of the dissociation of oxyhemoglobin. Under the 
ordinary tension of oxygen in the air, hemoglobin readily combines 
with oxygen, but if the external pressure be lowered sufficiently, then 
oxygen is given off, and the oxyhzemoglobin undergoes dissociation. 

1 Skandin. Arch. f. Physiol., Leipzig, 1891, Bd. ii. S. 236. 

* Arch. f. d. ges. Physiol., Bonn, 1894, Bd. lviii. S. 416; ‘‘Untersuch. u. d. Respira- 
tion und Circulation,” 1895, S. 26. 

3 Arch. f. d. ges. Physiol., Bonn, 1872, Bd. vi. S. 48. 

4 Tbid., 1871, Bad. iv. 8. 465; 1872, Bd. vi. 8. 23. 

5 [bid., 1873, Ba. vii. S. 296. 


Fic. 71.—Pfliiger’s lung catheter. 


CAUSES OF THE EXCHANGE OF GASES. 775 


The force with which the oxygen separates from the hemoglobin 
under these circumstances is called the tension of dissociation. The 
most important researches upon this subject are those of Hiifner.t 


The conditions of the dissociation of oxyhemoglobin are the same, whether 
it is a solution of freshly-made pure crystals of hemoglobin, or fresh 
defibrinated blood. The dissociation is dependent upon the concentration of the 
solution of hemoglobin ; thus, a weak solution is more readily dissociated under 
a given pressure than a strong solution. It is also affected by temperature.” 
As regards pressure, Hiifner found in the case of a solution containing 14 per 
cent of oxyhemoglobin at 35°, that, under a tension of oxygen of 152 mm., 
98°42 per cent. of the pigment was oxyhemoglobin, and 1°58 per cent. 
hemoglobin. When the tension of oxygen was reduced to 75 min., the 
percentages of oxyhemoglobin and of hemoglobin were respectively 96°89 and 
3°11, and with a lower pressure the dissociation became more rapid, as shown 
by the following curves :— 


460 150 40 350 “0 0 100 GO 60 7O 60 50 PAZ) 30 20 L0 Oo 


Fic. 72.—Curves of dissociation of oxyhemoglobin. The continuous line is for a 
solution containing 14 per cent. of hemoglobin, the interrupted line for a 
4 per cent. solution. 


It is now necessary to compare with the tension of the oxygen and 
carbon dioxide in the alveolar air the tension of those gases in the blood. 
For the determination of these tensions in blood Pfliiger® used a special 
instrument, known as the aérotonometer (see Fig. 75). 


The principle of the aérotonometer and of other similar instruments is this : 
Blood in contact with a mixture of oxygen, nitrogen, and carbon dioxide gives 
up some of its gases if their partial pressures are areater than those of the 
corresponding g gases in the mixture ; on the other hand, if the tensions of the 
gases in the blood be lower than the respective tensions of the gases in the 
mixture, the blood takes up gas. These interchanges persist until equilibrium 
is established, until the tension or partial pressure of the gas in the blood is 


1 Ztschr. f. physiol. Chem., Strassburg, Bd. vi. S. 109; Bd. xii. S. 582; Bd. xiii. 
S. 285 ; Arch. f. Physiol.. Leipzig, 1890, S. 1 ; tbid., 1895, S. 213. 

2 Brasse, Compt. rend. Soc. de biol., Paris, 1888, S. 660. 

3 Described by Strassburg, Arch. f. d. ges. Physiol., Bonn, 1872, Bd. vi. S. 65. 


776 CHEMISTRY OF RESPIRATION. 

equal to that of the corresponding gas in the mixture. In the aérotonometer 
the blood is made to pass in a thin layer through a glass tube or tubes, 
containing mixtures of gases of 
known quantity and tension, and 
it is arranged by practice that the 
tension of the gases in the tubes 
shall in the one case be greater, 
in the other case smaller, than the 
tensions of the corresponding gases 
in the blood. The gases in these 
tubes, after the blood has passed 
through them, are analysed, and 
from the alteration in the propor- 
tion in the two tubes it is possible 
to calculate the partial pressure 
of the gases in the blood. The 
aérotonometer is surrounded by a 
water-jacket with a temperature 
of 39°. 

Figure 74 shows the con- 
struction of a similar aérotono- 
meter, devised by Fredericq.!. The 
blood of the animal is rendered 
uncoagulable by the injection of 
peptone, in order that the experi- 
ment may be continued for an 
hour or two. The blood flows 
directly from the carotid artery 

Fic. 73.—Pfitiger’s aérotonometer. through the instrument, and _re- 
turns to the jugular vein. 

The aérotonometer contains, for example, at the commencement of the 
experiment, oxygen 10 per cent., carbon dioxide 5 per cent., and nitrogen 85 
per cent. of an atmosphere. The blood is passed through for one hour, and at 
the end of that time the gases in the aérotonometer are analysed, and found to 
be 14 per cent oxygen, 2°8 carbon dioxide, and the remainder nitrogen. From 
these figures it is concluded that the tension of the oxygen in the blood was 
14 per cent. of an atmosphere, and that of the carbon dioxide 2°8 per cent. of 
an atmosphere. 

Bohr? had previously introduced a modified aérotonometer, the “ hemat- 
aérometer,” through which a constant and rapid stream of blood could be 
maintained during each experiment (see Fig. 75). 


7 
| 
E 
E 
E 
= 
= 
= 


What, then, are the tensions of the gases of the blood 2? The results 
obtained by different observers are very discordant, and have given rise to 
considerable discussion. Nussbaum +‘ determined simultaneously on a_ 
dog the tension of the carbon dioxide in the blood from the right side 
of the heart and in the air of the alveoli; he found for the former a 
pressure of 3:81 per cent. of an atmosphere, and for the latter 5°84 
per cent. The tension of the carbon dioxide in normal alveolar air 
would be lower, for it would be mixed to a certain extent with the 


1 Centralbl. f. Physiol., Leipzig u. Wien, 1893, S. 33; Fredericq et Nuel, ‘‘ Eléments 
de physiologie humaine,” 3° édition, 1893, p. 156. 

2 Skandin. Arch. f. Physiol., Leipzig, 1891, Bd. ii. S. 238. 

3 Bohr, Zoc. cit. ; Fredericq, Centralbl. f. Physiol., Leipzig u. Wien, 1893, DS. oo 
Haldane and Lorrain. Smith, Journ. Physiol., Cambridge and London, 1896, vol. 
Xe Ps tOr. 

ry a f. d. ges. Physiol., Bonn, 1873, Bd. vii. 8. 296. 


CAUSES OF THE EXCHANGE OF GASES. 777 


tidal air. Wolffberg! found that the expired air of a dog contained 2°8 
volumes per cent. of carbon dioxide, or a tension of 21°35 mm. of mercury. 
Strassburg? found a tension of 54 per cent. of an atmosphere for the 


Fic. 74.—Fredericq’s Fic. 75.—Bohr’s hemataérometer. 
aérotonometer. 


carbon dioxide in the venous blood of the right side of the heart. This 
value, higher than those obtained by Wolffberg and Nussbaum, could be 
explained by the fact that the dog’s lungs were not so well ventilated, 
since tracheotomy had not been performed. In arterial blood Strass- 
burg found the tension of carbon dioxide to be 2:2 to 38 per cent. 
of an atmosphere, and for the oxygen Herter® obtained a tension of 10 
per cent. of an atmosphere. 

Very different results have been obtamed by Bohr? in experiments 
upon dogs. He obtained for the oxygen tension of arterial blood results 
as high as 101 to 144 mm. of mercury, and in nearly every case the tension 
was higher than the tension of oxygen in the air at the bifurcation of 
the trachea, in one case by asmuch as 88mm. As regards the tension of 
carbon dioxide very discordant results were obtained. In eleven experi- 
ments, in which the animal breathed pure air, the tension of the carbon 
dioxide in the arterial blood varied between 0 and 28 mm. of mercury; and 
in five other experiments, when the air inspired contained carbon dioxide, 


1 Arch. f. d. ges. Physiol., Bonn, 1871, Bd. iv. S. 478. 

? Tbid., 1872, Bd. vi. S. 77. 

3 Ztschr. f. physiol. Chem., Strassburg, 1879, Bd. iii. S. 98. 
+ Skandin. Arch. f. Physiol., Leipzig, 1891, Bd. ii. S. 236. 


778 CHEMISTRY OF RESPIRATION. 


the tension of that gas varied between 0°9 and 573mm. In the majority 
of the experiments the air of the trachea contained carbon dioxide with 
a higher tension than that of the gas in the blood. From these results 
Bohr concluded that the exchange of gases between the air of the alveoli 
and the blood in the lungs could not be accounted for by diffusion alone, 
and he suggested that the tissues of the lungs played an active part in 
the absorption of oxygen and in the excretion ‘of carbon dioxide. 

These results are so opposed to those obtained by Pfitiger and his 
pupils, that they naturally are subject to considerable criticism.’ In the 
first place, it is to be noted that the respiratory quotients obtained by 
Bohr durimg his experiments show values varying from 0°54 to 1:01, 
results which suggest imperfect and irregular ventilation of the lungs. 
Hiifner? contests Bohr’s results, and suggests that the irregularities in 
the results are due to a want of equilibrium in the tension of gases in 
the blood and in the air of the hemataérometer. He finds that equilibrium 
only obtains after several minutes and vigorous shaking of the blood in 
the apparatus. Similar objections have been made by Fredericq,? who 

obtained, for the tension of oxygen in the peptonised arterial blood of the 
dog, results always lower than the partial pressure of oxygen in the air 
of the alveoh. Further, the results obtained by Frederieq for the carbon 
dioxide agree with those given by Pfliiger and his pupils. 


The following values are given by Fredericq * for the tension of oxygen 
and of carbon dioxide in percentages of an atmosphere. 


Dog. 
r —— 
External Air. Air of Alveoli. Arterial Blood. Tissues. 
Tension of oxygen : » 20595 > 18 > 14 > 0 
External Air. Air of Alveoli. Venous Blood. Tissues. 


Tension of carbon dioxide . 0°03 << 2°8 < 3°81-5°4 < 5-9 


Quite recently Haldane and Lorrain Smith ® have studied the tension of 
oxygen in the arterial blood of man by a new method, which, they maintain, 
avoids the probable sources of fallacy in the aérotonometer. In this new 
method the tension of oxygen in the arterial blood is caleulated from the 
percentage of carbon monoxide breathed by the subject of the experiment, and 
from the final saturation of his blood with carbon monoxide. The results give, 
for the oxygen tension of human arterial blood, a value of 26:2 per cent. of an 
atmosphere, or 200 mm. of mercury. This value is about twice as high as that 
of the oxygen in the pulmonary alveoli, and if it be correct, it follows that 
diffusion alone does not explain the absorption of oxygen by the blood in the 
lungs. Haldane and Lorrain Smith discuss some of the possible sources of 
error in their method, such as the estimation of the saturation of the blood 
with carbon monoxide, the dissociation of carboxyhemoglobin, the effect of 
dilution of the hemoglobin, and the excretion or oxidation of carbon monoxide ; 
but the test experiments which they made confirm them in their opinion of its 
accuracy. 

Before, however, these results are accepted, further experiments are needed 
to test the method, for it is impossible with our present knowledge to judge 


1 See also criticism by Zuntz, Fortschr. d. Med., Berlin, 1890, Bd. viii. S. 856. 
2 Arch. f. Physiol., Leipzig, 1890, S. 10. 
3 Centralbl. f. Physiol. , Leipzig u. Wien, 1893, S. 33. 
4 Fredericq et Nuel, “Elements de physiologie humaine,” Gand, 1893, pp. 156-158. 
® Journ. Physiol., Cambridge and London, 1896, vol. xx. p. 497. 


CAUSES OF THE EXCHANGE OF GASES. 779 


it correctly. Some of the results obtained by Haldane and Lorrain Smith in 
their examination of these sources of fallacy are opposed to those obtained by 
Hiifner ! and Saint-Martin.” 


It is impossible to pass a verdict upon such discordant evidence, 
especially since further investigation is necessary to test the soundness 
of many of the experiments and of the conclusions based upon the results. 
It is permissible, however, to accept the provisional conclusion that the 
exchange of gases between the blood and the air in the lungs is effected 
by physical and chemical means, of which the most important is 
diffusion. 

According to the calculations made by Zuntz,’ the surface of the 
human lungs is 90 square metres, and through this there diffuse during 
quiet breathing about 300 cc. of carbon dioxide and about the same 
quantity of oxygen in a minute. Through the square centimetre of 
surface there would pass only the small quantity of 0:0003 cc. of gas. 
Now Exner’s * experiments show that through the square centimetre of 
a soap film 0°6 c.c. of air diffuse into an indifferent gas during one 
minute. The velocity of diffusion is proportional to the density of the 
gas, therefore a difference in tension of g,!59 of an atmosphere, or 0°3 
mm. of mercury, would be sufficient to make 0:0005 c.c. of oxygen pass 
through such a film in a minute. Further, the velocity of diffusion is 
proportional to the coefficient of absorption of the gas in the fluid in 
question, and inversely proportional to the square root of its density ; 
therefore the velocity for carbon dioxide is about thirty times greater 
than that of oxygen, and there is needed for carbon dioxide an even less 
difference of tension to cause a diffusion of gas from the blood into the 
alveoli. These considerations Zuntz supports by the following experi- 
ment. The bronchus of a frog’s lung is ligatured, and the lung is placed 
in carbon dioxide; within a minute the lung is distended, owing to the 
diffusion of carbon dioxide being, on account of its high coefficient of 
absorption, about forty-five times greater than that of air. If a tube be 
placed in the bronchus, the diffused gas can be collected and measured. 


Diffusion appears to be sufficient to account for the phenomena of gaseous 
exchange in the lungs. Other conditions possibly assist in the process. It 
has been shown that oxygen in combination with hemoglobin appears to have 
the property of driving out carbon dioxide.® 

Fleischl von Marxow® supposes that the sudden percussion given by the 
contraction of the ventricles to the blood assists in the liberation of the 
carbon dioxide in the lungs, and of oxygen in the arterioles supplying the 
tissues of the body. This theory, however, after the criticisms brought forward 
by Zuntz," appears to be untenable. 

1 Arch. f. Physiol., Leipzig, 1895, 8. 213. 

2 Compt. rend. Acad. d. sc., Paris, 1891, tome exii. p. 1232 ; 1892, tome exv. p. 835. 

3 Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xlii. S. 408. 

4 Ann. d. Phys. u. Chem., Leipzig, 1875, Bd. clv. S. 321, 443. 

5 This article, p. 771. See also Holmgren, Sitzwngsb. d. k. Akad. d. Wissensch. 
Math.-naturw. Cl., Wien, Bd. xlviii.; Werigo, Arch. f. d. ges. Physiol., Bonn, 1892, 
Bd. li. S. 321; 1892, Bd. li. S. 194 ; Zuntz, zbid., Bd. li. S. 191, 198. 

6 «Die Bedeutung des Herzschlages f. d. Athmung, eine neue Theorie des Respiration,” 
Stuttgart, 1887 ; Centralbl. f. Physiol., Leipzig u. Wien, 1887, S. 231, 662. 

7 Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xlii. S. 408. 


780 CHEMISTRY OF RESPIRATION. 


THE EXCHANGE OF GASES BETWEEN THE BLOOD AND THE TISSUES. 
INTERNAL RESPIRATION. 


From a comparative study! of the process of respiration, it is seen 
that the exchange of gases in the simplest forms of life is between the 
external medium and the protoplasm of the cell. 


In insects the smallest branches of the tracheal system carry oxygen to the 
individual cells,? which are often the seat of a most energetic combustion. In 
no case is this more marked than in the luminous organ of the glowworm 
(Lampyris splendidula), where, as Max Schultze® has shown, there are 
special cells at the end of the trachee. The phosphorescence still continues 
after the removal of the organ from the insect’s body, and under the microscope 
is seen to appear first in those parts of the cells which are around the ends of 
the trachee. The luminous cells have a great affinity for oxygen, as shown by 
the fact that they cease to give out light if confined in an atmosphere free 
from oxygen,? and readily reduce osmic acid. 


In the higher animals the blood is the medium which supples the 
tissues with oxygen and removes their carbon dioxide and other 
waste products. Reference has already been made to the theories of 
Lavoisier and Crawford ® concerning processes of oxidation in the blood, 
and we may proceed to consider the experimental evidence which has 
been advanced in favour of the view, that the blood is the chief seat of 
combustion. When blood is shed and kept at the temperature of the 
body, it becomes gradually poorer in oxygen,’ and there is always a dis- 
tinct darkening in the colour of arterial blood, even within the first few 
minutes after it is shed? These changes were investigated by Pfliiger in 
a series of determinations of the gases of the blood, ‘and he found that 
arterial blood received directly into a large vacuum, surrounded by hot 
water, gave a percentage of oxygen from 0-2 to 10 per cent. higher 
than the amount extracted by the slower method of the ordinary gas- 
pump. About the same time Alexander Schmidt § found that when the 
blood of an asphyxiated animal was exposed to a known quantity of 
oxygen, there was an absorption and disappearance of oxygen, and an 
increase in the amount of carbon dioxide. The capacity of blood to bring 
about this oxidation varied; that taken from contracting muscles could 
consume from 3 to 4 per cent., that from the heart 2 per cent., and blood 
from the hepatic vein 0°8 per cent. oxygen. It was shown by Afanassiew ? 
that only the blood corpuscles and not the serum could take up oxygen 
in this way, and Tschiriew !° found that lymph resembled the serum in 
containing no reducing substances. 


1 See Paul Bert, ‘‘Lecons sur la physiologie comparee de la respiration,” Paris, 1870 ; 
Johannes Miiller, “< Blements of oat siology,” Baly’ strans., vol. i. ; Pfliiger, Arch. f. d. ges. 
Physiol., Bonn, 1875, Bs sos: 

2 Finkler, Arch. if d. ges. Piao Bonn, 1875, Bd. x. S. 273; Kupffer, Beitr. 2. Anat. 
u. Physiol. als Festgabe C. Ludwig, Leipzig, 1875, S. 67. 

3 Arch. f. mikr. Anat., Bonn, 1865, Bd. i. S. 124, 

+ Milne Edwards, ‘‘ Lecons sur la physiologie et l’anatomie comparée,” tome viii. pp. 
93-120. > See p. 756. 

® Nawrocki, Stud. d. physiol. Inst. xu Breslau, Leipzig, Bd. ii. S. 144; Sachs, Arch. f. 
Anat., Ph ysiol. u. wissensch. Med., 1863, S. 348. 

4g Pfliger, Arch. f. d. ges. Physiol.., Bonn, 1868, Bd. i. S. 61; Bernard, Journ. de Vanat. 
et physiol. etc., Paris, 1858, tome i. S. 233. 

8 Ber. d. k. siichs. Geselisch. d. Wissensch. Math.-phys. Cl., Leipzig, 1867, Bd. xix. S. 99 ; 
Centralbl. f. d. med. Wissensch., Berlin, 1867, S. 356. 

° Ber. d. k. stichs. Geselisch. d. Wissensch., Leipzig, 1872, Bd. xxiv. 8. 253. 

10 Tbid., 1874, Bd. xxvi. S. 116. 


INTERNAL RESPIRATION. 781 


Alexander Schmidt considered that in the blood an active oxidation 
took place, for he concluded from his experiments that readily oxidisable 
substances and active oxygen or ozone existed in that fluid, and further 
that the oxidation in the body increased with the velocity of the blood. 
The hemoglobin was looked upon as the regulator of the consumption 
of oxygen, and this erroneous view, propounded by Lothar Mayer, is still 
accepted by some medical writers. 

As in all tissues, so in the blood there is a certain amount of 
oxidation, but the evidence about to be given will show that it is small 
and unimportant when compared with that taking place in muscles and 
glands. The blood is not the cause of the oxidation of the body, the 
cause is in the living cells of the tissues. 

The chief evidence is as follows :—A frog can live in an atmosphere 
of nitrogen for seventeen hours, and during this time gives off carbon 
dioxide, in fact during the first five hours it discharges as much as it would 
under normal conditions.?_ A frog will live a day or two in oxygen after 
its blood has been entirely replaced by normal saline solution,? and when 
in this condition its intake of oxygen and output of carbon dioxide are 
equal to that of a normal frog. The experiments of Finkler® show 
that the consumption of oxygen is independent, naturally within 
certain limits, of the velocity of the circulating blood. Further, the 
respiratory exchange of rabbits, deprived by bleeding of one-half of their 
hemoglobin, is equal to that of the same animals before the loss of 
blood ;® patients with simple anwmia or with severe leukemia absorb 
as much oxygen and excrete as much carbon dioxide as healthy men at 
rest and upon a similar diet.’ 

It was long ago shown by Spallanzani that living tissues removed 
from a recently killed animal took up oxygen and discharged carbon 
dioxide, and that this exchange was greater in most tissues than it was in 
blood. Similar experiments have been made by others.8 

Paul Bert placed tissues from a recently killed dog in air for 
twenty-four hours, the temperature varying from about 0° to 10°, and 
obtained the following results :— 


100 grms. of muscle absorbed 50°8 ¢.c, of oxygen, and discharged 56°8 c.c. of carbon dioxide. 


id brain 335 45°8 55 42°8 us 

- kidney ,, 37°0 Ss 15°6 - 

spleen 3 27°3 - 15°4 a 

a testis 5s 18°3 a Zia i 
broken | 

a bone & ; ,, aly (ey i 8'1 aA 
marrow | 


1 Pfliiger, Arch. f. d. ges. Physiol., Bonn, 1875, Bd. x. S, 251; 1878, Bd. xviii. S. 247; 
1893, Bd. liv. S. 333. 

2 Pfliiger, ibid., 1875, Bd. x. S. 251. 

®° Cohnheim, Virchow’s Archiv, Bd. xlv. 

4 Oertmann, Arch. f. d. ges. Physiol., Bonn, 1877, Bd. xv. S. 381. 

5 [bid., 1875, Bd. x. S. 368. 

° Pembrey and Giirber, Journ. Physiol., Cambridge and London, 1894, vol. xv. p. 449. 

7 Hannover, ‘‘De quantitate relativa et absoluta acidi carbonici ab homine sano et 
wgroto exhalati’’; Abstract given by Moller, Ztschr. f. Biol., Miinchen, 1878, Bd. xiv. 
S. 546; Pettenkofer and Voit, Ztschr. f. Biol., Miinchen, 1869, Bd. v. S. 319. 

8 Spallanzani, ‘‘Mém. sur larespiration,” trad. par Senebier, 1803, p. 86 ; G. Liebig, Arch. 
f. Anat., Physiol. wu. wissensch, Med., 1850, Bd. xvii. S. 393 ; Matteucci, Compt. rend. Acad. 
d. sc., Paris, 1856, tome xlii. p. 648; Ann. de chim. et phys., Sév. 3, Paris, tome xlvii. p. 129; 
Valentin, Arch. f. physiol. Heilk., Stuttgart, 1855, Bd. xiv. S. 431; 1857, N.F. Bd. i. S. 
285 ; Bernard, ‘‘ Lecons sur les propriétés physiol. des liquides,” Paris, 1859, tome i. p. 403 ; 
Paul Bert, ‘‘Lecons sur la physiologie comparée de la respiration,” Paris, 1870, p. 46; 
Regnard, ‘‘ Rech. expér. sur les combustions respiratoires,”’ Paris, 1879, p. 23. 


782 CHEMISTRY OF RESPIRATION. 


In pure oxygen the tissues absorb more oxygen, but do not discharge 
amuch greater quantity of carbon dioxide than they do in air; even 
in nitrogen or hydrogen the tissues continue to give off carbon dioxide.t 
The excised tissues of warm-blooded animals have a larger respiratory 
exchange than the corresponding tissues of cold-blooded animals, and 
differences are also observed in tissues from animals of different species.” 
The respiratory exchange of isolated muscle rises and falls, within certain 
limits, with the external temperature.* 

Experiments made upon excised tissues are liable to several sources 
of error. Putrefaction may begin, and cause an absorption of oxygen 
and a discharge of carbon dioxide;* this danger, however, is small in 
tissues removed directly after the death of the animal, and kept at a low 
temperature, and free from septic contamination. Another source of 
error is the loss of vitality in the tissues, and the accumulation of 
carbon dioxide and other waste products in the interior of the tissues. 

A much better method for the study of the respiratory changes in 
isolated tissues and organs is that introduced by Ludwig ;® an artificial 
circulation of blood is maintained, and the changes in the blood are 
determined. By these and similar experiments it can be shown that 
the tissues have the power of taking up oxygen, and also of oxidising 
various substances. This power is possessed in a different degree by 
the various tissues.’ Schmiedeberg has shown that benzyl alcohol 


(C,;H;CH,OH), and the aldehyde of salicylic acid (CH ) undergo 
no appreciable oxidation when placed in blood, but if blood containing 
one of these substances is made to circulate through a freshly excised 
kidney then considerable quantities of benzoic acid (C,H,.CO,H), or of 
salicylic acid (uiReger as 

Ehrlich® found that most tissues could reduce and decolorise 
alizarine-blue and other pigments, but that the colour returned when 
the tissues were exposed to the air. Tissues placed in normal saline 
solution containing oxyhemoglobin quickly reduce that substance, and 
in this respect muscle is the most effective. Bernstein® found the 
following values for the rate of reduction: Muscle 100, liver 81-47, 
involuntary muscle 72°4, and the mucous membrane of the stomach 
57:05; lung tissue, on the other hand, had a very feeble power of 
reduction. This relative power of reduction holds good for tissues 
taken from frogs and from mammals. Somewhat similar experiments 
had been previously made by Yeo;?° he supplied a frog’s heart with 


)! as the case may be, are produced. 


1 Spallanzani, ‘‘ Rapports de lair avec les étres organisés,” par Senebier, Genéve, 1807, 
tome i. p. 447 ; tome il. pp. 44, 56. 

2 Paul Bert, loc. cit. 

. 8Regnard, ‘‘Rech. expér. sur les combustions respiratoires,”’ Paris, 1879, p. 23. See 
also ‘‘ Animal Heat,”’ this Text-book, vol. i. p. 840. 

4 Hermann, ‘‘ Untersuch. u. d. Stoffwechsel der Muskeln,” Berlin, 1867, S. 37. 

5 Tissot, Arch. de physiol. norm. et path., Paris, 1894, tome xxvi. p. 838; 1895, tome 
XXVil. 

6 Arb. a. d. physiol. Anst. zu Leipzig, 1868. 

7 Schmiedeberg, Arch. f. exper. Path. wu. Pharmakol., Leipzig, 1876, Bd. vi. S. 233 ; 
1881, Bd xiv. S. 288, 379. For further details and references, see Neumeister, ‘‘ Lehrbuch 
der physiol. Chemie,” Jena, 1893, Th. 1, S. 8, e¢ seq. 

8 «Ter Sauerstoffbediirfniss des Organismus,”’ Berlin, 1885. 

9 Untersuch. a. d. physiol. Inst. d. Univ. Halle, 1888, Heft 1, 8. 107. 

W Journ. Physiol., Cambridge and London, vol. vi. p. 93. See also Vierordt, Zétschr. f. 
Biol., Miinchen, 1875, Bd. xi. S..195 ; Denning, zbid., 1883, Bd. xix. S, 483. 


GASES BETWEEN BLOOD AND TISSUES. 783 


solutions of fresh blood, and determined the reduction of the oxy- 
hemoglobin by means of the spectroscope. The results show that the 
heart during contraction reduces the solution about ten times as quickly 
as when it is at rest. 

The causes of the exchange of gases between the blood and the 
tissues.—The cause of the passage of oxygen from the blood to the 
tissues, and of carbon dioxide from the tissues to the blood, appears to 
be the difference in the tension of these gases in the tissues, and in the 
lymph and blood which surround them. It has been shown that the 
tissues have a great affinity for oxygen, and even store it up for the 
future oxidation of some of their constituents; and, on the other hand, 
that they are constantly producing carbon dioxide, and can even do this 
for a time in the absence of free oxygen. 

~The above conclusion is supported by the analyses of the gases of 
lymph and other secretions, and the determinations of the tensions of 
the gases in those fluids. Hammarsten? found that the lymph of a dog 
contained 0:1 volume per cent. of oxygen, 37°5 of carbon dioxide, and 
1°6 of nitrogen. These results have been confirmed and extended by 
other observers.?, Oxygen is present only in traces, but the quantity of 
carbon dioxide is less than that found in venous blood. This latter fact 
does not prevent the passage of carbon dioxide from the lymph to the 
venous blood, for Gaule* has shown that the tension of the gas is higher 
in the former fluid. It must be admitted, however, that further experi- 
ments are needed upon this point, for Gaule’s experiments are not con- 
clusive, and Strassburg found the tension of carbon dioxide in lymph 
to be intermediate between that in arterial and venous blood. Another 
probable cause of the smaller quantity of carbon dioxide in lymph is 
that many of the analyses were made upon lymph from the thoracic 
duct; the lymph would have been exposed in that situation to the 
action of arterial blood. This difficulty, however, is not present in some 
of the secretions. Thus, Strassburg‘ found in the urine and bile of a 
dog a tension of carbon dioxide equal to 9—7 per cent. of an atmo- 
sphere. Further, this physiologist has shown that, if air is injected into 
a ligatured portion of the intestine of a living dog, and after a short 
time is analysed, the tension of carbon dioxide is 7°7 per cent. of an 
atmosphere ; that is, considerably greater than the tension of the gas in 
the venous blood. 

These results are confirmed by the analyses® of some of the 

secretions of the body, and of various pathological transudations (see 
tables on p. 784). 
_ Ewald also determined the tension of carbon dioxide in some of these 
fluids, and found results as high as 7:51, 10-92, 10°73, and 11:5 per cent. 
of anatmosphere. It is therefore permissible to conclude that the tension 
of carbon dioxide in the tissues which produce, and are in contact with, 
these fluids is higher than the tension of that gas in the venous blood. 


1 Ber. d. k. stichs. Gesellsch. d. Wissensch. Math.-phys. Cl., Leipzig, 1871, Bd. xxiii. 
S. 617. 

2 Daehnhardt and Hensen, Virchow’s Archiv, Bd. xxxvii. S. 55, 68; Tschiriew, Ber. 
d. k. stichs. Gesellsch. d. Wissensch. Math.-phys. Cl., Leipzig, 1874, Bd. xxvi. S. 120; 
Buchner, A7b. a. d. physiol. Anst. zu Leipzig, 1876, Bd. xi. S. 108. 

3 Arch. f. Physiol., Leipzig, 1878, S. 469. 

4 Arch. f. d. ges. Physiol., Bonn, 1872, Bd. vi. S. 94. 

° Tables given by Halliburton, ‘‘Text-Book of Chemical Physiology and Pathology,” 
London, 1891, p. 392. 


784 CHEMISTRY OF RESPIRATION. 
Doc. 
Gi ees Venous Air of External 
, Blood. Alveoli. Air. 


Tension of carbon dioxide 
in percentage of an;/5-9 > 381-54 > 28 > 0:03 
atmosphere ! E | 


Carpon DioxipE. | 


| SECRETION. OXYGEN, F NITROGEN. OBSERVER. 
| Hoey able | Remoyable Total. 
| Vacuum: | by Acid: 
| 
~— a | | 
| Vols. Vols. | Vols. Vols. Vols. 
See nei, per cent. | per cent. per cent. | per. cent. 
Bile . : : al cee [aa Alen 561 0°4 | Pfliiger.? 
pemeyepree a0 Ey? Ok af 19°5) -|° 370 56° ... | Bogoljubow.? 
ra ‘ : se Bs . Dele e238 79°6 ay ge 
| Submaxillary saliva | 0-4 | 198 | 29°9 49-2 0-7 | Pfliiger.4 
(dog) 
Submaxillary saliva) 0°6 | 22° 42°2 64:7 0°8 x 
(dog) 
Parotid saliva (human) | 10 -| 3-5 40-60 | 43°5-63°5 255 Kulz.° 
| CARBON DIOXIDE. 
| |_ 
FLUID. | Oxycen. | ' NITROGEN. OBSERVER. 
peas able R emovabl = arnt 
| Vacuum. Mt Se 
Vols: _ 4j , Vols! Vols. Vols. Vols. 
per cent. | percent. | per cent. per cent. | per cent. 
Peritoneal : ee Oaiso 9°404 | 4°866 14:27 2°107 | Planer.® 
Hydrocele : 30) Peeps 32°49 32°45 | 64°94 2°05 | Strassburg.7 
y $s 
Subcutaneous cedema_ ‘Traces 22°25 9°11 31°36 Traces | Ewald. 
Subcutaneous cedema BS 21°88 31°18 53°06 53 ¥} 
(nephritis) 
Pleuritic . 5 : 0°68 | 39°34 15°59 54°93 I-33 3 
Aa F : j 0°54 18°54 25°99 | 44°53 1°87 “6 
Ee : : F et | 18°64 | 41°16 59°80 ok i 
Ns : ‘ ; 0°17 25°47 46°82 | 12°29 1:04 % 
Hydrothorax . ; 0:29 25°34 48°67 74°01 02875 (Wea 
1°01 25511 55°50 81°21 2°47 = 


3) . sit 


1 Fredericq et Nuel, ‘‘ Eléments de physiologie humaine,” 1893, 3° édition, p. 158. 

2 Arch. f. d. ges. Physiol., Bonn, 1869, Bd. ii. S. 173. 

3 Centralbl. f. d. med. Wissensch., Berlin, 1869, No. 42; Kowalewsky and Arnstein, Arch. 
f. d. ges. Physiol., Bonn, 1874, Bd. viii. S. 598. 

4 Arch. f. d. ges. Physiol., Bonn, 1868, Bd. i. S. 686. 

5 Ztschr. f. Biol., Miinchen, 1887, Bd. xxiii. S. 32]. 

6 Ztschr. d. k.-k. Gesellsch. d. Aertze zu Wien, 1859, No. 30. 

7 Arch. f. d. ges. Physiol., Bonn, 1872, Bd. vi. 8. 94. 

8 Arch. f. Anat., Physiol. u. wissensch. Med., 1873, S. 663 ; 1876, S. 422. 


ANIMAL HEAT. 


By M. S. PEmMBREY. 


ConTENts :--Thermometry, p. 785—Warm and Cold Blooded Animals, p. 787-— 
Temperature of Man and other Warm-Blooded Animals, p. 788—Of Cold- 
Blooded Animals, p..792—Hibernation, p. 794—Influence of Various Condi- 
tions upon Temperature, p. 798—Time of Day, p. 798—Age, p. 803—Muscular 
Work, p. 806—Mental Work, p. 807—Food, p. 809—-Sleep, p. 810—Sex, p. 810 
—Race, p. 811—Menstruation and Pregnancy, p. 812—Individual Peculiarities, 
p- 812—Temperature of Surroundings, p. 812 —Extreme Heat and Cold, p. 814 
—Baths, p. 818—Drugs, p. 820—Temperature of Different Parts of Body, p. 824 
—Of Arterial and Venous Blood, p. 826—Of the Skin, p. 829—Regulation of 
Temperature, p 831—Heat Production, p. 832—-Historical, p. 832—Relation to 
Chemical Changes, p. 833—Specitic Heat of Body, p. 838 —Seats of Heat Produc- 
tion, p. 889—Measurement of Heat Production, p. 844—Calorimetry, p. 844— 
Respiratory Exchange as a Measure of Heat Production, p. 847—Heat Produc- 
tion in Cold- Blooded Animals, p. 849—Regulation of Heat Loss, p. 850—Influence 
of Size of Body, p. 852—Influence of Nervous System, p. 854—Development of 
Power of Regulation, p. 865—Temperature of Body after Death, p. 866. 


THE higher animals have within their bodies some source of heat and 
some mechanism to regulate the production and loss of heat, for in the 
height of summer and in the depth of winter their mean temperature is 
constant. Of this fact the ancients had but an imperfect knowledge ; 
they had no thermometers, and therefore could only judge from their 
sensations. Observations dependent upon the sensations of heat and 
cold are necessarily imperfect and often fallacious. The invention, 
therefore, of thermometers was imperative, if exact data upon the 
temperature of animals were to be obtained 


The Introduction of Thermometers.—Towards the close of the six- 
teenth century the first thermometers appear to have been made.!_ The credit 
of the invention has been attributed chiefly to Sanctorius of Padua, and 
Galileo ; the former based his thermometer upon the expansion of air enclosed 
in a bulb at the end of a tube which contained a coloured liquid ; while Galileo 
is said to have made, in 1612, the first aleohol thermometer. Boyle introduced 
the alcohol thermometer into England, where Hooke, in 1665, recommended 
that the zero of the scale should be the freezing point of water, which he and 
Boyle found to be constant. In 1680, Newton suggested the boiling point of 
water for a further graduation of the thermometer, and Halley a few years 
later proved that the point was a constant one, and recommended the use of 
mercury in the construction of thermometers. Fahrenheit first replaced spirit 
by mercury in 1720, and, after several attempts at graduation, introduced the 
scale which now bears his name. The introduction of the centigrade ther- 


1 Holloway, ‘‘The Evolution of the Thermometer,” Se. Prog., London, 1895-96, vol. iv. 
p- 413; Liebermeister, ‘‘ Handbuch d. Path. u. Therap. des Fiebers,” Leipzig, 1875, S. 3. 


VOL. I.—50 


786 ANIMAL HEAT. 


mometer was due to Celsius in 1742.1 Throughout this article the centigrade 
scale is employed. 


THe DETERMINATION OF TEMPERATURE IN DIFFERENT PARTS 
OF THE Bopy. 


Varying quantities of heat are produced and lost in different parts 
of the body, and although the circulation of the blood tends to bring 
about a mean temperature of the internal parts, local differences are 
present. It is important, therefore, that the determinations should be 
made in those parts which have a temperature representing the internal 
temperature; and in order that the results may be comparable, the 
observations should as far as possible be made in similar anatomical 
positions. 

The most suitable place for the application of the thermometer 
varies under different conditions, and methods have to be considered, 
not only in as far as they are scientifically sound, but also in respect to 
their ease in practice. 


The rectum naturally offers the readiest access to the internal parts, and 
thermometers with or without a metal guard may be safely introduced 5 or 
6 cms. This method is the most suitable in the case of animals, and may be 
advantageously employed in infants. The vagina, uterus, and bladder of 
women and female animals of suitable size have a similar value to that of the 
rectum. 

In order to obtain the internal temperature of the body, the bulb of the 
thermometer, previously warmed in the mouth, may be inserted in the stream 
of wrine as it leaves the urethra.2 Apart, however, from the limited applica- 
bility of this method, there is a danger of a loss of heat by evaporation and 
radiation, but with care excellent results may be obtained. 

The avilla is a convenient place for thermometric determinations in man, 
for it is not liable to great variations in temperature. It is necessary, how- 
ever, that the axilla be closed well and long enough for it to attain the 
temperature of a closed cavity ; in very thin or wasted subjects it is difficult 
to effect this, and the temperature should therefore be taken elsewhere in such 
cases. 

The groin has also been selected by some physicians for the observation of 
temperature, but in man it is not so easy to retain the thermometer in the 
fold of the groin as in the closed axilla. The method is useful in the case of 
infants. 

The mouth, on account of convenience, has been widely selected for the 
clinical observation of temperature, but the readings of a thermometer, even 
when the bulb is placed under the tongue and the mouth is firmly closed, are 
liable to be low, owing to the danger of cooling of the tissues of the mouth, 
externally by cold air, internally by the inspired air. The mouth is also liable 
to considerable local variation of temperature. 

In order to obtain accurate results, the thermometer should be retained for 
eight minutes in the mouth, ten minutes in the well-closed and dry axilla, and 


1 For an account of the introduction of the thermometer into clinical use, see Wunder- 
lich, ‘‘ Medical Thermometry,” New Syd. Soc. Translation, 1871, p. 19; Lorain, “De la 
temperature du corps humain,” Paris, 1877, tome i. p. 39 et seq. 

* Stephen Hales, ‘‘Statical Essays,” London, 1731, 2nd edition, vol. i. p. 59; Martine, 
‘‘ Essays, Medical and Philosophical,” 1740, p. 335; Blagden, Phil. Trans., London, 1775, 
vol. Ixv. pt. 1, p. 114; Davy, ibid., 1844, pt. 1, p. 63; Mantegazza, Presse méd. belge, 


El 1863, tome xv. p. 111; Oertmann, Arch. f. d. ges. Physiol., Bonn, 1878, Bd. 
xyl. S. 101. 


WARM-BLOODED AND COLD-BLOODED ANIMALS. 787 


for three or four minutes in the rectum or vagina;! it should be kept in 
position for a minute or two after the mercury has become stationary. 


Different values have been given by various observers for the 
temperature in the mouth, axilla, and rectum; these will be critically 
examined later, but at present it may be stated that the temperature 
in the rectum is generally about three- or four-tenths higher than that 
in the axilla or mouth. Under certain circumstances, however, this 
relationship is altered. Thus Bosanquet? found that, although the 
temperature in the rectum was almost invariably higher than that in 
the mouth, the average difference being four-tenths, yet on some occa- 
sions, aS immediately after eating, the temperature in the mouth 
exceeded that in the bowel; while on others, as during vigorous 
exercise, the heat of the mouth sank considerably, e.g. to 35°6 (96° F 3 
that of the rectum rising to 37°7 (99°8) or 37°8 (100°). Violent 
exercise was found by Davy ® to lower the temperature in the mouth, 
and raise that in the axilla. The probable explanations of these differ- 
ences are that vigorous exercise would, by the increase of respiration, 
cool the mouth, and by increasing the vascularity of the axilla raise the 
heat in that part. The increase in the temperature of the mouth 
immediately after eating is probably due to the increase in the blood 
supply and activity of the muscles and glands in that cavity. 

In order to obtain the maximal temperature of the interior of the body, 
Kronecker and Meyer‘ used small bulbs of mercury, made according to 
the principle of Dulong and Petit’s outflow thermometer. The animal 
was made to swallow the small bulb, which, after evacuation by the 
bowel, was. placed in water gradually warmed until the mercury ex- 
panded to the point of outflow; the temperature of the water repre- 
sented the maximal temperature of the body. It was found by this 
method that the maximal temperature of a dog was 39°-2 and that of a 
rabbit 40°-2, the rectal temperatures varying respectively from 37°8 to 
38°°2, and 37°-0 to 37°9. Special thermo-electric methods will be 
mentioned in the discussion of surface temperature. 

Warm-blooded and cold-blooded animals.—An important differ- 
ence in temperature exists between the higher and lower animals. Those 
animals which are high in the scale of evolution, such as birds and 
mammals, have a high temperature, which is fairly constant and in- 
dependent of the temperature of the surrounding air. The lower 
animals, on the contrary, have a temperature dependent upon, and only 
slightly above, that of their surroundings, and thus liable to considerable 
variations. ‘This difference between the two classes is expressed by 
the terms “ warm-blooded” and “cold-blooded” animals. The classifica- 
tion, however, is not absolutely exact, for there are mammals, such as 
the marmot, hedgehog, bat, and dormouse, which are in an intermediate 
position; in warm weather these animals have a high temperature, 
which is fairly constant and independent of their surroundings, but in 
winter they become inactive, they hibernate, and their temperature 
falls and varies with that of their surroundings. On the other hand, 
there are bees, animals of a much lower order, which have and maintain 


1 Crombie, Indian Ann. Med. Sc., Caleutta, 1873, vol. xvi. pp. 554-559, 
2 Lancet, London, 1895, vol. i. p. 672. 

3 «* Researches,” London, 1839, vol. i. p. 199. 

+ Arch. f. Physiol., Leipzig, 1878, 8.2546. 


788 ANIMAL HEAT. 


a higher temperature than that of most cold-blooded animals, and are 
not reduced to spend the winter in a torpid state. 

Even in the case of the most perfectly warm-blooded animals there is 
a stage in which they resemble cold-blooded animals; infants and young 
animals born in an immature condition cannot maintain the temperature 
of their bodies at the normal height of the temperature of the adult; 
they need some accessory source of heat, such as the warmth of the 
parent's body. 


The terms “ warm-blooded” and ‘ cold-blooded” are inexact, for the tem- 
perature of a so-called cold-blooded animal living in the tropics may, under 
some circumstances, equal that of a mammal. John Hunter! showed that 
the essential difference in the two classes was in the constancy and incon- 
stancy of the temperature of the two groups, and he suggested that the warm- 
blooded animals should be called “animals of a permanent heat in all atmo- 
spheres;” the cold-blooded, “animals of a heat variable with every atmosphere.” 
Again, in 1845, Donders? pointed out the same fact, and called the two groups 
of animals, those with a constant and those with an inconstant temperature. 
A year or two later, Bergmann® discussed very fully the objections to the 
old terms, and suggested the definitions, ‘‘ animals with a constant temperature 
and animals with a varying temperature, or homoiothermic and poikilothermie 
animals.” In the present article, however, the terms ‘‘ warm-blooded” and 
“eold-biooded ” are retained, for they have been sanctioned by long usage, and 
their meaning is well understood. A further reason for their retention is 
found in the fact that there is no hard-and-fast line between the animals with 
a constant temperature and those with a varying temperature. 


The temperature of man and other warm-blooded animals.— 
The temperature of man.—The mean daily temperature of a healthy 
man varies slightly according to the part of the body in which it is 
observed: in the rectum it is 37°2 (98°96 F.), in the axilla 36°9 
(98°45 F.), in the mouth 36°87 (98°36 F.). These figures are the 
averages selected from the different observations given in the table on 
p. 789, and represent the mean temperature of a working day. 

The normal temperature of man is generally stated, as the result 
of John Davy’s numerous observations, to be 36°-9 (98°-4 F.) in the mouth, 
This, however, is wrongly looked upon as the mean temperature of 
twenty-four hours, for it represents the mean of observations taken 
chiefly during the active part of a day, from about 8 a.m. to 12 o'clock 
midnight; all observers agree that the lowest temperatures are found 
between midnight and early morning, and for very evident reasons the 
observations during this period are few. The mean temperature of 
twenty-four hours is therefore without doubt below 36°9 (98°-4 F.), and 
the observations of Casey, Clifford Allbutt, and Ogle show that this 
figure is even too high for the mean temperature of a working day. 
The average obtained from their results is 36°°7 (98°14 F.) for the 
temperature taken in the mouth. The observations upon the tem- 
perature between midnight and morning are so few, that it 1s im- 


aed at present to give the mean temperature of a day of twenty-four 
ours. 


z ‘“‘ Works,” Palmer’s edition, London, 1837, vol. iii. p. 16. 
* “ Der Stoffwechsel als die Quelle der Eigenwirme bei Pflanzen und Thieren,” Wies- 
baden, 1847, S. 12-13. 


3 **Gottinger Studien,” 1847, Abth. 1, S. 595. 


TEMPERATURE OF MAN AND ANIMALS. 789 


Place of | 


Maximum. Minimum. | men paratue Obsdivatiot: Observer. | 
37°°2 36°°5 | 36 °9 | Mouth Davy.! 
37°°5 | 36°°8 37°°2 - Gierse.? 
37°°0 (ntl36"3; > St 36°°7 s | Hooper. 
37°°36 36°°63 | 37°°05 - Hallmann.? 
eels | 36°°635 ei 36°°93 F su aE hee 
| 37°49 36°39 | 36°°8] Pe | Lichtenfels and Frohlich. | 
37°°0 36°°1 36°°7 a | Casey.® 
37°°0 36°°6 36°°8 * Clifford Allbutt.? 
37°-0 36°-2 36°65 | - Ogle.® 
38°'0 /os6r2 37°°0 Axilla Wunderlich.® 
37°°3 ) oS6erk a - Ringer and Stuart.!° 
ples a) © 86%15e || 36°°89 a Liebermeister.! 
Bers a |e 368-73 36°°9 5i Damrosch.* 
37°°4 EE 36°°7 a Billet. #3 
37°°9 | 36°°3 371 - Billroth.4 
37°°8 | 367-5 37°°2 Rectum | Jiirgensen.¥ 
37°°1 36°°6 36°°85 5 Neuhauss. }® 
ah ae 37°°1 a | Bosanquet.!? 
| 37°°35 36°95 | 37°13 | x Jaeger. 18 
37°°4 36°15 36°°8 | | Nicol.29 
| 
37°°3 36°°1 36°°9 Urine | Richet.”° 
37°°95 36°74 37°72 | o Mantegazza. 7} 
| sis 36°°9 Ae Gley.” 
£ Bak | oy | Rondeau. 
37° °6 | 386°°2 36°°9 oe Pembrey.”4 


The temperature of other warm-blooded animals.—The observations 
upon the temperature of animals are numerous, but have not been 
repeated often enough under different conditions which are known to 
atfect the temperature of man. On this account, and also because 
animals are known to have a somewhat variable temperature, it is 
impossible in most cases to give the mean temperature. The following 
table gives some of the results obtained by different observers :— 


1 Phil. Trans., London, 1845, pt. 2, p. 319. 

2 <*Quenam sit Ratio Caloris Organici, etc.,” Halae, 1842, p. 40. 

3 Med. Times and Gaz., London, 1866, vol. ii. p. 483. 

4 Quoted from Landois, ‘‘ Lehrbuch d. Physiol.,” Aufl. 3, S. 406. 

5 Denkschriften d. k. Akad. d. Wissensch. Math.-naturw. Cl., Wien, 1852, Bd. iii. 
Abth. 2, S. 113. 

§ Lancet, London, 1873, vol. i. p. 200. 

7 Journ. Anat. and Physiol., London, 1872, vol. vii. p. 106. 

8 St. George's Hosp. Rep., London, 1866, vol. i. p. 221. 

® “* Medical Thermometry,” p. 95. 

10 Proc. Roy. Soc. London, 1877, vol. xxvi. p. 186. 

11 «* Handbuch d. Path. u. Therap. d. Fiebers,” 1875, S. 78. 

2 Deutsche Klinik, Berlin, 1853, Bd. v. S. 317. 

13 These, Strasbourg, 1869. 

4 Arch. f. klin. Chir., Berlin, 1862, Bd. ii. S. 331. 

15 << Die Korperwarme des gesunden Menschen,” Leipzig, 1873. 

16 See p. 813. 

7 Lancet, London, 1895, vol. i. p. 672. 

18 Deutsches Arch. f. klin. Med., Leipzig, 1881, Bd. xxix. S. 522. 

19 Result of observations not yet published. 

°0 Rev. scient., Paris, 1885, tome ix. p. 629. 

*1 Presse méd. belge, Bruxelles, 1863, tome xv. p. 111. 

8 cape from Richet, Rev. scient., Paris, 1885, tome ix. p. 432. 

id. 
*4 Result of observations not yet published. 


199 


ANIMAL HEAT. 


Animals. 


Average Rectal 
Temperature. 


Horse 


Ox 


Cow 


[ 
Zt 
Sheep: .f ates, | 


Rabbit . : nc 
Ferret . 


Guinea-pig | 
Rat (black and white) 
Rat (white) 

Mouse (black 


white) 
Monkey (Rhesus) . 


and 


Echidna (Hystrizx) 


Ornithorhynchus . 


37°°9 (100°-2) 
37°°7 — (99°:9) 
37°°9 (100°-2) 
38°85 (101°°9) 


38°-9 
38°°6 ) 
38°°6 (101°°5) 
) 
) 


(102°-0) 


40°°6 (105°*1 
40°-2 (104°°4 
40°-0 (104°-0) 


40°1 
38°" 
37°" 
38°" 
38°" 


(104°-2) 
(100°°9) 
1 (100°-2) 
(101°'8) 
(101°°5) 


oO CO % oO 


38°: 
38°" 
39°: 


(101°°8) 
(101°-7) 
(103°:3) 


o> “I 00 


(ov) 
oo 

° 
bs 


(101°°7) 


(102°'5) 
(101°°8) 
(101°-7) 
(102°:8) 
(101°-7) 


wo 
DH 
° 

~T cb ~1 0d 


‘93 (100°-2) 


39°-21 (102°°6) 
87°°4  (99°°4) 


"+85 (101°-9) 


37°°5 (995) 
37°-96 (100°'3) 
37°°4  (99°°3) 


38°°4 (101°-1) 


Zao (Silas) 
(cloaca or in 
abdomen) 
32°) = (90°'5) 
(cloaca) 
24°85) (76°56) 
(cloaca) 


® Veterinary Journ., London, 1885, vol. xx. 


Extremes of 
Observations. 


ia 

i 

ee 

a a 
Noo eH 

bo I 


39°°6-41°°0 


37°°15—38°°45 
38°°3-39°°9 
38°*1-39°-2 


38°"0-39° 6 


37°°0-38°" 
37° °4-38°° 
36°*1-38°° 


mS 6c Or 


36°°9-39°: 


| 


25°*5-80° 


26°°5-84°° 


bo 


24°-4-25°°2 


p- dll. 


Number of 
Observations. 


On 150 horses 
600 on 100 ,, 
On 212 i$ 
On 352 cows 
and oxen 
39 on 1 cow 
On 87 cows 
On 100 cows 
On 24 sheep 
284 on 6 ,, 
On more than 
100 sheep 
On 100 sheep 
190 on 17 dogs 
44 on several ,, 
6 on 6 3 
On more than 
200 dogs 
On 100 dogs 
On 41 cats 
169 on 4 young 
pigs 
On more than 
100 pigs 
72 on 27 rabbits 
7 on 7 93 
sLonll0s,; 
On 8 ferrets 
About 50 ob- 
servations 
19 on 5 guinea- 
pigs 
35 observations 
40 on 4 guinea- 
pigs 
30 on 1 guinea- 
pig 
16 on 4 rats 
60 on 2 rats 
27 on 8 mice 


22 on 2 mon- 
keys 

5 on 2 speci- 
mens 


7 on 7 speci- 
mens 

2 on 1 speci- 
men 


Observer. 


Strecker. 
Fohringer.? 
Hobday.? 
Robertson.* 


Siedamgrotzky.? 
Hobday.? 
Singleton.® 
Davy. 
Siedamgrotzky.4 
Hobday.? 


Singleton.® 
Siedamgrotzky.# 
Hoppe.‘ 
Obernier.® 
Hobday.* 


Singleton.® 
Hobday.? 
Siedamgrotzky.4 


Hobday.? 


Hale White.® 
Obernier.® 
Pembrey. 
Hobday.? 
Finkler.!° 


Pembrey. 


Richet.!! 
Colasanti.!2 


Pitts. 


Pembrey. 
Pitts. 
Pembrey. 


Hale White and 
Washbourn. ® 

Mikloucho 
Maclay.4 


Semon.?® 


Mikloucho 
Maclay.4 


[Continued on next page. 


' Ellenberger, ‘‘ Vergleichende Physiol. der Haussiiugethiere,” 1892, Bd. ii. Th. 2, S. 81. 
* Journ. Comp. Path. and Therap., Edin. and London, 1896, vol. ix. p. 286. 


+ Deutsche Zischr. f. Thiermed., Leipzig, 1875, Bd. i. S. 87. 
° Veterinarian, London, 1888. 
” Virchow’s Archiv, 1857, Bd. xi. S. 459. 
* Journ. Physiol., Cambridge and London, 1890, vol. xi. p. 1. 
” Arch. f. d. ges. Physiol., Bonn, 1882, Bd. xxix. S. 112. 

il Rev. scient., Paris, 1884, tome viii. p. 306. 
2 Arch. f. d. ges. Physiol., Bonn, 1877, Bd. xiv. 8. 123. 
8 Journ. Anat. and Physiol., London, vol. xxv. p. 379. 
4 Proc. Linn. Soc. New South Wales, 1883, vol. viii. p. 425 ; vol. ix. p. 1205. 
19 Arch. f. d. ges. Physiol., Bonn, 1894, Bd. lviii. S. 229. 


6 «* Researches,” London, 1839, vol. i. p. 208. 


8 “* Der Hitzschlag,” Bonn, 1867. 


TEMPERATURE OF MAN AND ANIMALS. 


Animals. 


Fowl (common) 


Duck 


Goose 
Pigeon . 


Ostrich . 


Average Rectal 
Temperature. 


42°°8 
41°°6 
43°°6 (110°: 
42°-1 (107°°8) 
41°°7 (107°°0) 
40°°9 (105°°6) 


(109°:0) 


37°°3  (99°:2) 


(106°°9) | 
5) 


Extremes of 


Observations. 


41°-7-43°°9 
40°*6—43°°0 
43°+4-43°-9 
41°°4-43°-0 
EW as EEG 
40°-0-42°*5 


36°°9-37°°8 


791 
N 

Observations Ounerres 
On 14 fowls Davy. 
On 111 fowls | Hobday.? 
On 8 ducks Davy.? 
On 24 ducks Hobday.’ 
On 5 geese Davy.! 
20 on 4 pigeons} Corin and Van 

Beneden.? 

On 5 ostriches | Hobday.? 


In the next table are collected the results of various observations 
upon other mammals and birds ; in most of these cases the figure given 
for the temperature represents the result of a single observation *:— 


x 


Animal. Temperature. 
Monkey (Simia aygula) 39°°7 —(103°°5) 
releh icici hyo kui oa et BORD (B25) 
Elk 39°°4 (103°) 
Goat . | 39°-4 (103°) 
Tiger ele oneeze 99.) 
Ichneumon « | 39°°4 (103°) 
Squirrel . 38°°9 (102°) 
Manatee. P 39°°4 (103°) 
Whale 38°°8 (101°°8) 
Greenland whale 38°°9 (102°) 
Seal 38°°9 (102°) 
Porpoise Sf 1D) (9975 

| Pigeon 42°°2 (108°) 
Thrush . 42°°8 (109°) 
| Turkey . 42°°8 (109°) 
Guinea-fowl 43°°3 (110°) 
Pheasant z 42°°6 (108°°7) 
Great titmouse sill AAG OS (AGED) 
Sparrow . sil 42s 3(10¢°-8) 
Swift | 44°-0 (111°-2) 
Heron 41°-0 (105°°8) 
Redwing . | 43°83 (109°-9) 
Fieldfare a 2 Bere Aa sa) 
Yellowhammer a Adce2 ec CLOSES) 


Place of Observation. 


Rectum 


9 


Abdomen 


9 
2) 


39 


3) 
Rectum 
33 


39 


Observer. 


Davy. 
Hunter.® 
Davy.® 

22 

33 


bi) 
29 3 fe 
Martine.’ 


9) 
Scoresby.® 
Tiedemann.® 


29 
Davy. 
2) 


? 


Richet. 1° 
Tiedemann. 
Davy. 
Tiedemann. 
Prévostand Dumas." 
Hobday. 

peal 


29 


———— 


The above tables show that the rectal temperature of most of 
the mammals is higher than that of man; the most marked ex- 
ception is found in the monotremata, the lowest group of the mam- 
malia; thus the temperature of the porcupine echidna (HLehidna hystrix) 
varies from 25°°5 to 34°2, that of the duckbilled platypus (Ornitho- 


1 «‘ Researches,” London, 1839, vol. i. p. 186. 


2 Journ. Comp. Path. and Therap., Edin. and London, 1896, vol. ix. p. 286. 

3 Arch. de biol., Gand, 1887, tome vii. p. 265. 

+ For the temperature of other animals, see Gavarret’s ‘‘ De la chaleur produite par les 
étres vivants,” Paris, 1855, p. 92; Richet, Rev. scient., Paris, 1884, tome viii. p. 298. 


5 <‘ Works,’ Palmer’s edition, vol. ili. p. 340. 


6 <¢ Researches,” London, 1839, vol. i. pp. 181, 188. 
7 « Essays, Medical and Philosophical,” 1740, p. 337. 


8 Milne Edwards, ‘‘ Lecons,” tome viii: p. 16. 


9 «‘ Physiologie,” Bd. i. S. 454. 


10 Rev. scient., Paris, 1885, tome ix. p. 202. 


Ann. de chim. et phys., Paris, Sér. 2, tome xxiii. p. 61. 


792 . ANIMAL HEAT. 


rhynchus anatinus) from 24°4 to 25°°2. In the case of birds the 
temperature is generally two or three degrees higher than that of 
mammals. 

In the observation of the temperature of animals, it is necessary, 
if comparable results are to be obtained, to insert the thermometer 
to a similar extent each time, and to prevent struggling of the animal 
before and during the time of observation. Finkler! found that the 
rectal temperature of guinea-pigs was 36°11, 38°°7, and 38°°9, at a depth 
of 2:5, 6, and 9 ems. respectively. Aronsohn and Sachs? found 
that the rectal temperature of normal rabbits rose to over 40° after 
a short chase, Hobday® observed a rise to +1°1 in the case of sheep 
and pigs, and Mott‘ has noticed a rise of one or two degrees in the 
temperature of monkeys, owing to a similar cause. Moreover, the times 
of observation should as far as possible be similar, for animals show 
a daily variation in temperature. Rabbits extended on their backs and 
tied down lose so much heat that their temperature rapidly falls 
(Legallois, Richet.’) 


The temperature of cold-blooded animals.—It has already been 
shown that there is no hard and fast line between the so-called warm-blooded 
animals—those with a constant temperature, and the cold-blooded animals— 
those with a varying temperature. Further proofs of this will now be given, 
and others will be brought forward when the subject of hibernation is 
considered. 

John Hunter® made some interesting observations upon the temperature 
of bees. He found in the month of July, when the temperature of the air was 
12°-2, and a north wind was blowing, that the temperature at the top of a hive 
full of bees was 27°°8. In December the temperature of the hive was 22°°8, 
when that of the external air was only 1°-7.___ A single bee has so little power 
of keeping itself warm, that it quickly becomes numb and almost motionless 
when exposed to the moderate cold of a summer night. The aggregation, 
however, of vast numbers in a hive ensures the production of enough heat to 
keep the bees active even in winter, and for this production of heat a constant 
supply of food is necessary. The warmth of the hive is needed also for 
the eggs, pup, and larve, for Hunter found that they would not live in a 
temperature of 17°. The wax is by means of the warmth kept so soft that the 
bees can model it with ease. . 

Numerous observations upon the temperature of bees were made by 
Newport,’ who found that, when the insects were in a state of activity, 
their temperature was above that of their surroundings; the larva and pupa 
had a lower temperature than the imago, and less power of generating as well 
as of maintaining their temperature. In winter the temperature of a hive, 
when the bees were in a state of repose, fell considerably, and varied slowly 
with that of the atmosphere ; the bees did not become torpid, but passed into 
a deep sleep, broken at intervals by periods of activity. A very low atmo- 
spheric temperature aroused the bees, and thus prevented any great fall in the 
temperature of the hive. Thus on January 2, 1836, at 7.15 a.m., when the 
temperature of the air was —7°°5, that of the hive was —1°1, and the bees were 
quiet, but after the bees were disturbed by tapping the hive, the temperature 


1 Arch. f. d. ges. Physiol., Bonn, 1882, Bd. xxix. 8. 117. 

2 Tbid., 1885, Bd. xxxvii. S. 232. 

3 Journ. Comp. Path. and Therap., Edin. and London, 1896, vol. ix. p. 286. 
4 Note communicated to the writer. 

5 Rev. scient., Paris, 1884, tome viii. p. 300. 

6 ‘* Works,” Palmer’s edition, London, 1837, vol. iv. p. 427. 

7 Phil. Trans., London, 1837, pt. 2, p. 253. 


TEMPERATURE OF COLD-BLOODED ANIMALS. 793 


was raised to 21°:1 within fifteen minutes. On another occasion, when the 
external temperature was 1°°4, that of the hive full of active bees was 38°°9. 
The temperatures of individual nurse bees, brooding over the young bees in 
the combs, was as high as 29°:4, while the temperature of the cell after the bee 
left it was 24° and that of the air 22°. 

Similar results have been obtained by Reaumur,! Huber,? Dutrochet,* 
Nobili and Melloni,* and others. 

In marked distinction to bees are other insects, such as some wasps and 
flies, which can pass the winter in a state of torpor, their temperature varying 
with that of their surroundings. 

The difference between the temperature of the animal and that of its 
surroundings varies in different classes of the cold-blooded animals. The 
following are results obtained by different observers :— 


| === — = = — 


Anima Has Sets A aye ae Onserver 
Viper . : : 205 (68> )2 | 14°°4 Hunter. ® 
Python. : : 24°°4 (76°) hes6 Sclater.? 
Turtle . - : 28°°9 (84°) 26°°4 Davy.® 
55 . ‘ : 27°°8 (82°) | 28°°9 Czermach.® 
MERTOR | + : 17°-2 (63°)® 16°°7 Davy.® 
a. tT eye 14°-4 # 
capes } : ; 8°°9 (48°) | Gra Czermach.® 
Proteus. : ; 17°°8 (64°) 13°°3 se 
ee 20°°6 (69°) 18°°6 Hunter.® 
Trout . - : 14°°4 (58°) 13°°3 Davy. 
—-*. 5°*6 (42°) 4°-4 i 
| Flying fish . : 25°°6 (78°) 25-3 ra 
| Shark . 3 oh 25%) (ii) 23°°7 Ff 
Bonito. _. . |  37°-2 (99°) 26°°9 ft 
Crayfish : : 267-1 (79%) 26°°7 a 
cee, | eee ae) | 22°°2 s 
Snail (Indian) : 24°°6 (76°°25) 24°°6 Be | 
Earthworms . é 14°°7 (585) 13°83 Hunter. ® | 
Black Slugs . : 13° (55°:25) I) ee | 
Leeches : : 13°°9 (57°) 1Rs3} 3 
Scarabeus . : 23. Gi) 24°°4 Davy. 
| Glow-worm . ‘ 23°°3 (74°) 2258 a 
| Locust . é sai DOS DN (P2°5) | 16°°7 a3 
| Papillio Aganem- 27 i (80%e5) 2556 9 
non | 
Scorpion F ai 20°73 \(f4, 30) 26°°1 ag 
| 


The results of observations on the temperature of other cold-blooded animals 
will be found recorded in the works of Tiedemann,! Rudolphi,! Newport,” 
Valentin,!* Dutrochet,!! Milne Edwards,! and Gavarret.!¢ 


“‘Mém. pour servir a histoire des insectes,” Mém. 18, tome iv. 
“Noy. obser. sur les abeilles,” tome ii. p. 336. 
Ann. d. sc. nat., Paris, 1840, “‘ Zoologie,”’ Sér. 2, tome xiii. p. 5. 
4+ Ann. d. chim. et phys., Paris, Sér. 2, tome xlviii. p. 207. 5 Rectal. 
6 «* Works,” Palmer’s edition, London, 1837, vol. iv. p. 131 et seq. 
7 Proc. Zool. Soc., London, 1862, p. 365. 
8 ** Researches,” London, 1839, vol. i. p. 189; ibid., p. 219. 
9 Journ. de phys., Paris, 1821. 10 << Physiologie,” Bd. i. S. 454. 
11“ Grundriss der Physiol.,” Bd. i. S. 151 et seg. 
22 Phil. Trans., London, 1837, pt. 2, p. 259. 
13 Repert. f. Anat. u. Physiol., 1839, Bd. iv. S. 359. 
4 Ann. d. sc. nat., Paris, 1840, ‘‘ Zoologie,”’ Sér. 2, tome xiii. p. 5. 
15 «* Tecons sur Ja physiol.,”’ tome viii. p. 7. 
16 Article ‘‘Chaleur animale,” ‘‘ Dictionnaire encyclopédique d. sciences médicales,” 
Paris, 1874, Sér. 1, tome xv. ; ‘‘ De chaleur produite par les étres vivants,” Paris, 1855, 
p. 113. 


1 
2 


oo 


794 ANIMAL HEAT. 


A consideration of the above lists shows that the temperature of cold- 
blooded animals is generally a few tenths of a degree above that of their 
surroundings, but that in some exceptional cases, as that of the python and 
a fish known as the bonito (Thynnus pelamys), it may be 10 degrees 
above the external temperature. Although these high temperatures are well 
authenticated, the causes have not been determined ; it is to be noted, how- 
ever, that the high temperature is more marked in the incubating female 
python than in the male which does not incubate, and that the bonito has very 
vascular red muscles.! 

The temperature of many of the cold-blooded animals is often below 
that of the air, owing to the great loss of heat by evaporation, and to 
the large surface exposed, especially by insects, to cooling by radiation and 
conduction. 

Hibernation.2— Certain animals, on the approach of winter, and in some 
cases even in summer, retire to their burrows or other shelter, become inactive, 
and fall into a torpid state. All the activities of the body are greatly reduced, 
and the temperature falls to a point only slightly above that of the surround- 
ings. Such is the condition known as hibernation. 

The animals in whom hibernation has been definitely proved to take 
place, do not belong to any one class; examples are met with in mammals, 
reptiles, amphibians, insects,’ molluses, and lower animals, but no cases 
are known among birds. As regards fishes, no well-authenticated cases of 
hibernation are known; there are doubtful instances in which the fish has 
been imprisoned by the freezing of the water, and yet has remained alive for 
some time. 

The following mammals hibernate—spermophile, marmot, hamster, 
squirrel, hedgehog, dormouse, bat, bear, and beaver. In some cases the 
animal lays up stores of food, upon which it feeds when it awakes at 
intervals during the period of hibernation ; in other cases, there is a special 
accumulation of fat within the animal’s body before the commencement of the 
torpid state. 

The further account of this subject refers only to the hibernating 
mammals. 

The condition of the animal during hibernation. — Respiration. — The 
frequency of respiration is greatly diminished, and the rhythm is irregular 
and often of the Cheyne-Stokes type. A hibernating dormouse may not give 
a single respiration for ten minutes, then may take ten or fifteen breaths, and 
again cease breathing for another period of several minutes. The same animal 
in an active condition breathes at the rate of eighty or more in a minute. 
Similar results have been obtained in the case of other animals. 

Determinations of the respiratory exchange have been made. Spallanzani+ 
found that during hibernation marmots and bats could be kept for four hours in 
carbon dioxide gas without suffering any ill effects, whereas a bird and a rat 
placed in the chamber at the same time died at once. Saissy °® observed that 
the amount of oxygen taken up by dormice varied as the activity of the 
animal, and that during well-marked hibernation there was hardly any intake. 


1 See p. 849. 

* Since this section was written, there has appeared a monograph by Dubois, ‘‘ Physio- 
logie comparée de la marmotte,’’ Paris, 1896, which contains a large number of original 
observations and an abstract of the previous work upon hibernation. The bibliographical 
index contains references to 145 papers. 

> Trimen, ‘‘ Butterflies of South Africa,” vol. i. p. 231. See also Nature, London, 2nd 
April and 11th June 1896. 

4 Spallanzani, ‘‘ Memoirs on Respiration,” edited by Senebier, 1804. See article 
‘Chemistry of Respiration,” this Text-book, vol. i. 

° “*Recherches expérimentales anatomiques, chimiques,” etc., 1808; Reeve, ‘‘On 
Torpidity,”’ 1809; Edwards, ‘‘ De Vinfluence des agens physiques sur la vie,” Paris, 
1824, 


HIBERNATION. 795 


These results have been extended and confirmed by Marshall Hall,! Regnault 
and Reiset, Horvath,” and others.* 

Regnault and Reiset* determined the respiratory exchange of several 
hibernating marmots, and found that the intake of oxygen was about 
one-thirtieth of that of an active animal, and only about two-fifths of the 
oxygen appeared in the carbon dioxide discharged. The following are two 
examples :— 


Grms. per Kilo. and Hour. 
Condition of Marmot. 
Oz COz COz 
Intake. Output. O2 
Hibernating - 0°48 0°37 566 
Awake x 2 1'198 1°312 796 


A further proof that oxygen was stored up in the body of the hibernating 
animal was found in the increase in weight of a marmot during profound 
torpidity ; it gained as much as 5°9 grms. in five days. 

The output of carbon dioxide was investigated by Horvath, who found that 
the amount varied according to the animal’s activity. The following is an 
example of his results :— 


F Son ditt Rectal Temperature | Respirations CO2 
Animal. Condition. Temperature. of Air. per Minute. in Grms. 
} : 
Sisel,° 163) Hibernating 3 yf 5 ‘025 in three 
grms. hours. 
Awake 33°°5 13° 95 | 457 in half 
an hour. | 


Similar results have been obtained in the case of dormice and bats.® 

According to Saissy,’ a hedgehog can absorb all the oxygen from the 
air in which it is confined, and can even live for fifteen minutes in pure 
nitrogen, whereas a rat under similar conditions dies in less than three 
minutes. 

Circulation.—The force and frequency of the heart-beat is much reduced 
during hibernation; in the case of the bat and dormouse to fourteen and 
sixteen per minute or even less, the rate in the active animal being above 100 
per minute. On applying a stethoscope to the chest of a hibernating bat, 
no sound of the heart-beat can be heard, whereas, when the animal awakes and 
becomes active, the sounds are so loud that they can be heard by the ear placed 
one inch away from the animal (Hill and Pembrey). 


1 Phil. Trans., London, 1832, pt. 2, p. 335; Barkow, ‘‘ Der Winterschlaf,” 1846, 
here numerous additional references are given. 

2 Verhandl. d. plys.-med. Gesellsch. in Wurzburg, 1878, Bd. xii. ; 1879, Bd. xiii. ; 
1880, Bd. xiv. ; 1881, Bd. xv. 

3 Pembrey and Hale White, Jowrn. Physiol., Cambridge and London, 1895-96, vol. 
xix. p. 477. 

4 Ann. d. chim. et phys., Paris, 1849, Sér. 3, tome xxvi. p. 429. 

» Allied to the marmots. 

6 Pembrey and Hale White, Joc. cit. 

7 Deutsches Arch. f. d. Physiol., Halle, 1817, Bd. iii. S. 135. 


796 ANIMAL HEAT. 


The blood during hibernation has, according to most observers,! an 
arterial colour in the veins; on the other hand, Marshall Hall states that it 
has a venous hue even in the arteries. Further details concerning the 
circulation will be found in the works of Reeve, Edwards, Barkow, Horvath, 
and Dubois.” 

The gases in the blood of hibernating and of active marmots have been 
determined by Dubois,? who found that during hibernation the arterial blood 
contained as much oxygen, the venous blood less oxygen, and both arterial 
and venous blood an excessive quantity of carbon dioxide, as compared with 
the gases of arterial and venous blood from active animals. 

Digestion.—The activity of the digestive organs varies according to the 
habits of the different animals; some, such as bats, take no food during the 
winter; others, such as the dormouse, hamster, and marmot, store up food, 
which they consume during short periods of activity.+ 

Nervous system.—The excitability of the nervous system is_ greatly 
depressed, and the nervous and other tissues of the body resemble those of 
cold-blooded animals, in retaining their excitability for a long time after 
removal from the body.* 

Temperature.—During hibernation the temperature resembles that of a 
cold-blooded animal, rising and falling with that of the surroundings. In 
this way the rectal temperature may fall as low as 2° without injurious effects 
following. When the animal awakes from hibernation its temperature 
generally rises rapidly many degrees above that of the air; the most rapid rise 
takes place after the rectal temperature has reached 17°, when there may be 
a further rise to 32° in forty minutes ; this is accompanied by an increase in 
the activity of the animal, and in the output of carbon dioxide.® 

If the animal be fully awake and active, its temperature resembles that of a 
warm-blooded animal; a fall in external temperature increases its activity, 
temperature, and respiratory exchange, while a considerable rise has the 
opposite effect.® 

The power of heat regulation in hibernating animals.—The capacity for 
maintaining a constant temperature varies according to the condition of the 
animal ; during well-marked hibernation this power is very slight, and resembles 
that of a cold-blooded animal, but when the animal is active its power of 
regulating its temperature is comparable to that of a warm-blooded animal. 

There is an intermediate stage when the animal is listless and inactive, 
with a bodily temperature below that of its normal in summer, but considerably 
above that of its surroundings. In this condition its power of regulation 
resembles that of an immature mammal; within certain narrow limits it is able 
to maintain its temperature, but when exposed to cold its temperature falls, 
and it passes into a cold-blooded condition.? 

The awakening from hibernation.—One of the most interesting phenomena 
in hibernation is the sudden rise in temperature which occurs when the animal 
awakes from its torpor. This rise is so great and sudden that there is 
nothing comparable to it, not even the sudden rise seen in some cases of fever. 

Thus Horvath® found the temperature of a sisel rise from 14° to 32° in 
one hour and forty minutes, the temperature of the air remaining 14°. In the 


‘In addition to other references, see Bernard, ‘‘ Lecons sur la chaleur animale,” 1876, 
p. 374. 


* See references on pp. 794-795. 

3 Compt. rend. Soc. de biol., Paris, 1894, 22 décembre. 

4 For further details see the works mentioned on p- 794; also Gavarret, ‘‘De la 
chaleur produite par les étres vivants,” Paris, 1855, p. 466. 

° Horvath, doc. cit. ; Pembrey and Hale White, Joc. cit. 


6 Pembrey and Hale White, Zoc. cit.; Hunter, ‘‘ Works,” Palmer's Edition, London, 
1837, vol. iv. pp. 141-145. 


* Pembrey and Hale White, Joc. cit. 
8 Verhandl. d. phys.-med. Gesellsch. in Wiirzburg, 1878, Bd. xii. S. 162. 


HIBERNATION. 797 


bat and dormouse the rise may be even more rapid, as shown by the following 
examples :!— 
i 17° when very quiet | 
= 34° when awake and! Temperature of 
active, fifteen | air=1.0°-5; 
minutes later 
fe 13°-5 when asleep | 
Dor = 35°75 when awake! Temperature of 
ormouse— i > Sila atd é SF feeue 
| and active, one | air =9°°5. 
hour later 


Bat—Rectal temperature | 


The rapid rise in temperature is accompanied by a marked quickening of 
the respiration and of the heart-beat, and by active movements of the body. 
In some cases, especially in the marmot, there is a convulsive shaking of the 
body. ‘The increase in the muscular activity appears to be the chief cause of 
the increased production of heat, although Horvath? and Dubois? do not 
accept this view. It is to be noted, however, that Horvath draws attention to 
the increased respiration and heart-beat, and remarks that when once the 
shivering movements of the marmot have commenced, nothing can prevent 
the animal from awaking, and its temperature from rising. Dubois considers 
that the liver plays the most important part, for he finds that extirpation of 
the ganglia of the solar plexus, or ligature of the portal vein, and of the 
inferior vena cava just above the liver, prevents the rapid rise of temperature 
observed in an awakening marmot. An examination, however, of the experi- 
ments made by Dubois shows that the influence of the nervous system is 
considerable, for the greater the motor paralysis the smaller was the rise in 
temperature. Removal of the cerebral hemispheres does not prevent hiber- 
nation or the rise of temperature observed when the animal awakes. The 
latter phenomenon, however, is abolished by section of the spinal cord at the 
level of the fourth cervical vertebra. 

In the case of bats and dormice, Pembrey and Hale White have shown 
that the sudden rise in temperature, when the animal awakes, is accompanied 
by a greatly increased discharge of carbon dioxide. 

The causes of hibernation.—The cause generally assigned for hibernation 
is cold, but a more careful consideration of the facts long ago showed 
that cold could not be the sole cause of the phenomena. Most observers 
who have worked at the subject of hibernation have found that even 
severe cold will not cause an active animal to hibernate. Saissy® observed 
that a low temperature alone was ineffectual, but the continued effect of 
cold, and a limited amount of air for respiration, caused a marmot to pass 
into a typical hibernating condition even in summer. Mangili® found that 
torpid marmots and bats were awakened by exposure to severe cold, and that 
confined air would not cause hibernation. Valentin and Horvath’ have 
recorded cases of marmots hibernating under normal conditions during 
summer; the animals were very fat, and the torpid condition was in all 
respects similar to that in winter. Pallas states that if the hamster be buried 
four or five feet below ground in a confined space, it begins to hibernate.® 

Dormice have been kept throughout the winter in a warm room (16°), and 
yet they hibernated, and were not aroused when the external temperature 


1 Pembrey and Hale White, Zoc. cit. 2 Loc. cit., pp. 170, 175. 

3 Compt. rend. Soc. de biol., Paris, 1893, pp. 210, 235 ; 1894, pp. 36, 115. 

4 Tbid., 1893, p. 156. 

5 «* Recherches expérimentales anatomiques,” etc., 1808. 

® Arch. f. d. Physiol., Halle, 1808, Bd. viii. S. 433, 437, 444. 

7 Verhandl. d. phys.-med. Gesellsch. in Wiirzburg, 1881, Bd. xv. S. 209. 

8 See also Paul Bert, ‘‘Lecons sur la physiol. comp. de la respiration,’ Paris, 1870, 
p. 508. 


798 ANIMAL HEAT. 


was 20°; the warmth, however, delayed the onset of torpidity by two 
months, and made it less profound.! Further, it is found that in some cases 
hibernation takes place in the dry hot season ; thus there is in Madagascar an 
animal, closely allied to the hedgehog, and called the tanrec (Centetes 
ecaudatus), which buries itself and becomes lethargic in the dry season, when 
its insect food is inaccessible.2 The reptiles and many of the invertebrate 
animals of tropical climates seek their hiding-places and fall into a state of 
torpor during the dry season, when the heat is most intense. Torpidity in 
dormice and hedgehogs may be delayed or prevented by a plentiful supply of 
food.* 

Want of food and cold seem to be the most important factors, but there 
must be some other condition, at present unknown, to explain the cases of 
marmots hibernating during the summer. It is certain that many species of 
animals which become torpid in one country do not become so in another. 
This fact, according to Barton,‘ is very noticeable in the United States, for 
many species which hibernate in Pennsylvania and other more northern 
parts of the country, do not hibernate in the Carolinas and other southern 
parts of the continent. Attempts have been made, but without success, to 
find anatomical differences, especially as regards the blood vessels of the brain, 
which would account for hibernation.° 

The most recent theory is that of Dubois,° who maintains that hibernation 
is caused by an autonarcosis with carbon dioxide. In support of this theory 
he adduces the following facts, namely, the accumulation of carbon dioxide in 
the blood, and the production of torpidity in marmots exposed to an atmo- 
sphere containing about 40 per cent. of carbon dioxide. 


THE INFLUENCE OF VARIOUS CONDITIONS UPON THE TEMPERATURE OF 
MAN AND OTHER WARM-BLOODED ANIMALS. 


Numerous observers have insisted upon the occurrence of small 
variations in the temperature of healthy men and animals, and have 
shown by experiments that these variations are due to several causes. 

Influence of day and night.—The temperature of man is subject 
to slight daily variations; it rises during the morning and afternoon, 
it falls during the evening and early part of the morning. Upon 
the points of maximal and minimal temperature, and the range of 
variation, the results differ considerably, as the table on p. 799 
shows. 

It will be seen from these results that there is more agree- 
ment upon the time of the minimal daily temperature than upon that 
of the maximum. The causes of this difference are mainly two: in the 
first place, there appears to be a rise and then a fall in temperature 
before the ascent to the maximum begins. Thus Birensprung found a 
rise in the early morning to 11 A.M., then a fall to 2 p.m.; and Damrosch 
observed that the temperature rose from 7 A.M. to 10 A.M., and then fell 


1 Berthold, Arch. f. Anat., Physiol. u. wissensch. Med., 1837, 8. 63. 

2'This statement of Cuvier and Bruguitre is contested by Brown-Séquard (‘‘ Ex- 
perimental Researches applied to Physiology and Pathology,” New York, 1851, p. 25), who 
maintains that the tanrec hibernates in the winter season, when the external temperature 
is from 15 to 23 degrees. 

3 Reeve, ‘‘ An Essay on the Torpidity of Animals,” 1809. 

4 Trans. Am. Phil. Soc., Phila., 1799, vol. iv. p. 121. 

5 Mangili, Arch. f.°d. Physiol., Halle, 1808, Bd. viii. S. 446 ; Saissy, Deutsches Arch. 
f. a. Physiol., Halle, 1817, Bd. iii. S. 136. 

6 Compt. rend. Acad. d. sc., Paris, 1895, tome cxx. p. 458 ; Compt. rend. Soc. de biol., 
Paris, 1895, 3e Mars. 


INFLUENCE OF DAY AND NIGHT. 799 
until 1 p.m. This small morning variation preceding the rise to the 
maximum would explain some of the uncertainty concerning the 
time of the maximum. The second important cause is the difference 
in the meals of the English and German people; the “/riihstuch” 
is a small meal compared with the English breakfast, and thus, in 
the observations made in England, the morning fall, beginning about 
ten o'clock, would be masked by the increased warmth due to a hearty 
meal. 


Time of Maximum. Time of Minimum. Sas Peet Observer. 
Between 8 a.m. and} About 1 A.M. 1 Mouth. Davy. 
5D P.M. 
About mid-day Between 11 p.m. and Ons Pr Gierse. 
2 A.M. 
At 7 P.M. Between 11 p.m. and One a Hooper. 
8 A.M. 
Between 10 A.M. and | Between 11 p.m. and 0°73 re Hallmann. 
7 P.M. 7 A.M. 
Between 4 p.m. and | Between 1 A.M. and 0°°51) ae Lichtenfels and 
5 P.M. 7 A.M. 0°56 J Frohlich. 
Between 4 p.m. and| About 2 A.M. 0°-9 3 Casey. 
7 P.M. 
Between 4 p.m. and | Between 12 p.m. and 0°5 5 Clifford Allbutt. 
-8 P.M. 7 AM. 
About 7 P.M. About 6 A.M. 0°°8 is Ogle. 
Between 2 p.m. and | Between 2 a.m. and 0°°6 i Crombie.2 
8 P.M. 7 A.M. 
Between 9 A.M. and | About 1 A.M. 1°°2 Axilla. Ringer and 
6 P.M. Stuart. 
Between 10 A.M. and | Between 2 A.M. and 1°°29 Fe, Liebermeister. 
6 P.M. 3 A.M. 
About 5 p.m. Between 7 P.M. and 0°°4 m Damrosch. 
7 AM. 
At 3 P.M. At 3 A.M. 1158} as Billet. 
Between 6 p.M. and | About 4 A.M. 0°°8 4f Barensprung.® 
7 P.M. 
Between 4 p.M. and | Between 2 a.m. and ie Rectum. Jurgensen. 
9 P.M. 8 A.M. 
Between 7 A.M. and} Between midnight 1°4 OF Jaeger.* 
and 7 P.M., gene- and 4 A.M. 
rally about 4 P.M. 
About 6 P.M. About 2 A.M. he sy = Nicol. 
At 4 P.M. At 7 A.M. las Urine. Richet.® 
Between 5 p.m. and | Between 3 A.M. and ae “ Pembrey. 
8 P.M. 6 A.M. 


Other causes for the different results are to be sought in the fact 
that the observations are not comparable as regards the age, health, 
meals, and work of the subjects of the experiment, and the temperature 
was taken in different ways. 

The following curve (Fig. 76), given by Ringer and Stuart,° shows the 
daily fluctuations of temperature in a boy 12 years old; the thermometer, 
a non-registering one, was kept in the closed axilla throughout the 


1 The references are mostly given on p. 789 of this article. 

2 Indian Ann. Med. Sc., Calcutta, 1873, vol. xvi. p. 550. 

3 Arch. f. Anat., Physiol. wu. wissensch. Med., 1851, S. 159. 

4 Jaeger, Deutsches Arch. f. klin. Med., Leipzig, 1881, Bd. xxix. S. 525. 
® Rev. scient., Paris, 1885, tome ix. pp. 430, 629. 

6 Proc, Roy. Soc. London, 1877, vol. xxvi. p. 187. 


800 ANIMAL HEAT. 


time, and the readings were taken every 
hour. The boy was in good health, and 
was kept in bed during the observations. 

In the next chart! (Fig. 77) are the 
daily curves representing the results of 
Ogle, Clifford Allbutt, Casey and Rattray, 
and those of Crombie, who, during 
residence in JBengal, made _ observations 
upon his own temperature and that of 
natives. 


A.M. Noon P.M. 


ai 

° 
oF 

is} 


‘9 
-8 
7 
“6 
5 
4 
“<3 
2 
“1 
0 
“9 
8 
“7 
‘6 
“5 
4 
“3 
+2! 
“tl 
0 
9 
“8 
7 
“6 
“5 
4 
*3ig 
+2 
om | 
ae) 
oe] 
“8 
+7 


Fic. 76.—Daily variations 
Fe Oe Fic. 77.—Daily variations in temperature 
oy Ringer and Stuart. observed by Ogle, Clifford Allbutt, 


The observations extend Casey and Rattray, and Crombie. 
over 50 hours. 


The next curves (Fig. 78) represent the daily variation according to 
Jiirgensen and Liebermeister’s observations.” 


' 


51718] 9 10 Nip 213] 4151 ¢ C 
Morning Mid-day Evening Night Morning Mid-day 
Fig. 78.—Daily variations in temperature observed by Jiirgensen and Liebermeister. 
The observations extend over 30 hours. 

The average results of Thierfelder’s*? observations upon the daily 
variations of temperature found in subjects of different age and sex are 
shown in the following table :— 

1 Crombie, Indian Ann. Med. Sc., Caleutta, 1873, vol. xvi. p. 568. 


> ““ Handbuch der Pathologie und Therapie des Fiebers,” Leipzig, 1875. 
3 Schmidt's Jahrb., Leipzig, 1851, Bd. lxxi. 


INFLUENCE OF DAY AND NIGHT: Sor 


res | Noon. Evening. 

Newly born . : =| 37°°41 37°80 37°61 
Children , : | 37°°37 38°:07 37°12 
Men my 37°°0 37°°25 36°-60 

Adults } on Bde 37°22 37°55 37°10 
| Aged lirica = x Taike| 37°25 37°58 | 37°31 


The following curve! (Fig. 79) represents the mean results of records 
of the temperature of the urine taken by Richet, Gley, and Rondeau; the 
times of meals were 7 A.M. 11 A.M., and 7 P.M., and no observations were 
made between 9 o’clock in the evening and 7 o’clock in the morning. 


Daily variations in 
temperature, similar to 77 eee EL 
CEE REEEEEEE EEE 


those already described, ; 
have been observed in « 
natives of different ; 
races living in the * 


aad ; E ‘ cea 
s regards the 

causes of ? ‘the daily SS a7 
variation in tempera- sECEEEE HEE ECA 
ture, muscular activity , SERRE REE AK 


sesmeepecennneaeesen cere 
Sesraneeecsuseaeensee: 
Blase iseeleataleteickl stele 


Za i ER INE 


and food appear to be , 
the most important ; 
factors. In ordinary = 
life man is most active 
and takes food during * 
the day > and = least Fic. 79.—-Curve of daily variation in the temperature of 

active during the night. the urine. 

Debezynski? found that 

continuous work carried on throughout the night reversed the variation, 

so that the maximal temperature 3 37°8 occurred in the morning, and the 
minimal 35°'3 in the evening. N fate -watching without work had a similar 
but eer effect, the maximal temperature 3 37°°7 being in the morning, 
the minimal 57°°5 in the evening. Jaeger +4 ret obtained similar results, 
and Krieger® states that work during the night and rest during the day 
reverse the daily variation. The influence of inversion of the ordinary 
routine of daily life has been studied by U. Mosso ®; a series of observa- 
tions of the rectal temperature was first made during a period when work 
was performed in the daytime and sleep taken at night, and the two chief 
meals were at 11 A.M. and 6 P.M.; then there followed another period in 
which sleep was taken during the day and work performed at night, and 


1 Richet, Rev. scient., Paris, 1885, tome ix. p. 430. 

2 Davy, ‘‘ Researches,” London, 1839, vol. i. p. 169 ; Jousset, Arch. de méd. nav., Paris, 
1883, tome xl. p. 124; Maurel, Bull. Soc. danthrop. de Paris, 1884, tome vii. p. 381. 

3 Jahresb. ii. d. Leistung. . . . d. ges. Med., Berlin, 1875, Bd. i. S. 248. 

4 Jaeger, Deutsches Arch. f. klin. Med., Leipzig, 1881, Bd. xxix. S. 533. 

5 Ztschr. f. Biol., Miinchen, 1869, Bd. v. S. 479. 

° Arch, ital. de biol., Turin, 1887, tome viii. p. 177. 


VOL. I1.—51 


802 ANIMAL HEAT. 


the two chief meals were at 11 P.M. and 6 a.m. Notwithstanding the 
inversion of daily routine, Mosso found that the morning rise still took 
place about the same time, and, as the following curves (Fig. 80) will 
show, the daily variation was not inverted, although the sleep during 
the day caused a fall, and getting up in the evening a marked rise, in 
temperature. The effect of the experiment was to disturb the regularity 
of the daily variation, but on the fourth day the influence of the sleep 
during the day was most marked, a fact which seems to indicate that, 
if the habit were long continued, a tendency to inversion would be 
observed in the daily variation of temperature. 


Normal. 


Routine of life inverted. 
4th. day, April 15th.1885. 
[aa ee fa Fa Fa, 


TANT 
PREOUE NAG 
AMPEG a eb 


1 2 '3 ‘4 '5 6 7 '8 9 10 ‘I! Hours of sleep and rest. 6 8° <5" 1008) ea 


Fic. 80.—Daily variations in temperature observed during U. Mosso’s experiments. 


Buchser,! an engineer, who was accustomed to sleep during the day 
and work at night, found that his average morning temperature was 
37°25, while his evening temperature was 36°'8. 

There are secondary causes of the daily variation. The periods of 
high and low bodily temperature more or less correspond with the times 
of day when the external temperature is high and low respectively. 
Further, there appears to be a certain periodicity, the result of long-con- 
tinued habits of life, stamped upon the processes which regulate tem- 
perature. This is shown by the fact that the daily variation still 
persists, although it may be slightly modified, during a period of fasting 
or night-watching” and a similar daily variation is observed in the 
respiration and pulse,® in the discharge of urea,‘ and in the capacity 


1 Quoted from Carter, Journ. Nerv. and Ment. Dis., N.Y., 1890, vol. xvii. p. 785. 

* Jiirgensen, ‘‘ Die Korperwirme des gesunden Menschen,” Leipzig, 1873; Ogle, St. 
George's Hosp. Rep., London, 1866, vol. i. p. 228; Crombie, Indian Ann. Med. Sc., 
Calcutta, 1873, vol. xvi. p. 597; Liebermeister, ‘‘ Handbuch d. Path. u. Therap. des 
Fiebers,”’ 

5 Lichtenfels and Fréhlich, Denkschriften d. k. Akad. d. Wissensch. Wien, 1852, Bd. iii. 
Abth. 2, S. 113; Neuhauss, Virchow’s Archiv, 1893, Bd. exxxiv. S. 365. See also this 
article, p. 813; Bosanquet, Lancet, London, 1895, vol. i. p. 672; Damrosch, Deutsches 
Arch. f. klin. Med., Leipzig, 1853, S. 342; Jousset, Arch. de méd. nav., Paris, 1883, tome 
xl. pp. 284-5 ; Chossat, Mém. Acad. d. sc. de I’ Inst. de France, Paris, 1843, tome viii. p. 540. 

* Weigelin, Arch. f. Anat., Physiol. u. wissensch. Med., Leipzig, 1868, S. 207. 


INFLUENCE OF AGE. 803 


for muscular work.! Daily variations in the output of carbon dioxide 
and in the intake of oxygen have been observed by Prout, Pettenkofer 
and Voit, Fredericq,? and others; these variations in metabolism more 
or less correspond with those observed in the temperature, and will be 
found discussed more fully in another part of this work.? 

Rest in bed throughout the day does not abolish the daily variation ; 
it is still present, although modified, in cases of disease, attended or 
unattended by fever; the morning rise still takes place even when light 
is excluded (Ogle). 

In animals, daily variations in temperature have also been observed, 
but upon this point there are few exact observations taken throughout 
the day and night. Strecker,t from observations upon 150 horses, found 
the average temperature between 6.30 A.M. and 8 A.M. to be 37°9, that 
between 5 P.M. and 6.30 P.M. to be 37°93; but the minimum was 37°:2 
and the maximum 38°°6. In the case of oxen, Robertson ® found the 
average morning temperature 38°°7, the evening temperature 38°°9 ; in 
the cat the minimum is 37°8 at 7 AM. and the maximum 39°08 at 
10 p.m. (Bidder and Schmidt).6 Hunter states that the temperature of 
an ass was 0°°5 higher in the evening than in the morning. According 
to the observations of Siedamgrotzky,’ the maximal daily temperature in 
horses was 38°:2 at 6 P.M., the minimum 3775 at 4 A.M.; in a cow the 
maximum was 39°1 at 5 pM. and the minimum 38°7 at midnight. 
Corin and Van Beneden § have observed the daily variation in pigeons,® 
and find that the minimum is at 4 a.M.; that from this time to 8 A.M. 
there is a rise, then a fall to noon, followed by a rise to the maximum 
at 4 p.M.; the daily variation amounts to 2°2. In the case of horses, 
Hobday ?° finds that the rectal temperature at 10 A.M. is 37°°6, and 37°°9 
at 5 P.M.; in the case of the rabbit, cat, and dog, Carter ? has shown that 
there is a distinct rhythm of temperature, the maximum occurring in 
the evening (7-11 P.M.) and the minimum in the morning (7-11 A.M). 

We may conclude that the daily variation in temperature is one of 
the features of a corresponding variation in the activity of the tissues of 
the body, as shown by the rate of the contraction of the heart, the 
frequency of respiration, the intake of oxygen, the output of carbon 
dioxide, the discharge of urea, and the capacity for muscular work. 

The influence of age.—The temperature of newly-born infants and 
animals is generally equal to, or even slightly higher than, that of their 
parents, but it is much less stable, and is liable to much greater varia- 
tions. 

Edwards 2 found that the temperature of newly-born pups, kittens, 
and rabbits fell when they were removed from their warm surroundings, 
and continued to fall until it reached a point a few degrees above the 

1 Patrizi, Arch. ital. de biol., Turin, 1892, tome xvii. p. 134. 

2 Prout, Ann. Phil., London, 1813, vol. ii. p. 330; vol. iv. p. 331; Pettenkofer and 
Voit, Zischr. 7. Biol., Miinchen, 1866, Bd. ii. S. 459; Fredericq, Arch. de biol., Gand, 
1882, tome iil. p. 729. 

> ** Chemistry of Respiration,” this Text-book, vol. i. p. 721. be 

4 Ellenberger, “‘Vergleichende Physiologie der Haussiugethiere”’ 1892, Bd. ii. Th. 2,S. 81. 

° Veterinary Journ., London, 1885, vol. xx. p. 311. ; 

6 «*Die Verdauungssafte und der Stofiwechsel,” Leipzig, 1852, S. 346. 

7 Deutsche Ztschr. f. Thiermed., Leipzig, 1875, Bd. i. S. 87. 

8 Arch. de biol., Gand, 1887, tome vii. p. 265. 3 

9 See also Chossat, Mem. Acad. d. sc. del Inst. de France, Paris, 1843, tome vil. p. 540. 

1 Journ. Comp. Path. and Therap., Edinburgh and London, 1896, vol. ix. p. 286. 


1 Journ. Nerv. and Ment. Dis., N.Y., 1890, vol. xvii. p. 782. 
12 “< De l’influence des agens physiques sur la vie,” Paris, 1824. 


804 ANIMAL HEAT. 


temperature of the air. Newly-born guinea-pigs, however, were able 
to maintain their temperature, provided that the exposure to cold was 
not very great. Edwards therefore divided the young warm-blooded 
animals into two classes, the warm-blooded and the cold-blooded. In 
the former class the young animals are at birth blind, helpless, in some 
cases naked, and cannot maintain their temperature. The members of 
the latter class are even at birth in a condition of great development ; 
their eyes are open, they are active, and maintain a fairly constant 
temperature. It was also found that young birds could be classified 
in a similar manner. As the animal grows, the fall in temperature on 
exposure becomes less and less, and about the fifteenth day after birth 
a fairly constant temperature can be maintained. 

Edwards showed by comparative experiments that the fall in tem- 
perature on the exposure of newly-born animals was not due to the 
greater cutaneous surface, in proportion to the mass of the body, as com- 
pared with the ratio in adults. The absence or presence of feathers or 
fur was only of secondary import, for an adult sparrow was able to 
maintain its temperature even after all its feathers had been plucked 
out. 

Raudnitz! in 1888 discussed very fully the temperature of infants. 
He made observations upon the variations of temperature in infants at 
birth and during the first few days after birth. The influence of the 
large cutaneous surface in relation to the mass of the body, and the loss 
of heat from the skin, were shown by experiment to be only secondary 
causes of the irregular temperature. Observations made upon the effect 
of affusions of cold water showed that the rectal temperature in infants 
a day or two old rose in the case of strong subjects, but remained 
stationary or fell in the case of the weak. Raudnitz concludes that 
the imperfect development of the power of regulating temperature is 
the chief cause of the variable temperature in infants; and it has been 
shown by the writer? that this is also the cause in the case of young 
immature animals. 

Before birth the temperature of the infant is slightly higher than 
that of the mother’s uterus;* at birth the average rectal temperature 
is 37°°5 (99°°5). Soon after birth, especially after the first bath, the 
temperature falls to about 36°°75 (98°15), and during the next week or 
two rises somewhat, and remains fairly constant between 37°25 (99°:05) 
and 37°°6 (99°68). These figures are to be looked upon only as average 
results, for all observers appear to agree that the daily fluctuations of 
temperature are greater and more uncertain in children than in adults.* 


} Htschr. f. Biol., Miinchen, 1888, Bd. xxiv. 8. 423. At the end of this paper is a very 
complete list of papers bearing upon the subject. 

> Pembrey, Journ. Physiol., Cambridge and London, 1895, vol. xviii. p. 363. 

® Wurster, Berl. klin. Wehnschr., 1869, Nr. 37; Alexcetf, Arch. f. Gynack., Berlin, 
Bd. x. S. 141; Fehling, ibid., Bd. vii. S. 146; Preyer, ‘‘Specielle Physiologie des 
Embryo,” Leipzig, 1885, S. 362. 

* Barensprung, Arch. f. Anat., Physiol. wu. wissensch. Med., 1851, S. 138; Finlayson, 
“On the Normal Temperature of Children,” Glasgow Med. Journ., 1869, p. 186 ; Squire, 
Trans. Obst. Soc. London, vol. x. p. 274; Raudnitz, Ztschr. 7. Biol., Miinchen, 1888, 
Bd. xxiv. S. 423; here other references will be found; Jiirgensen, ‘‘ Die Korperwirme 
des gesunden Menschen,” 1873, S. 49 ; Davy, ‘‘ Researches,” London, 1839, vol. i. p. 156 ; 
Crombie, Indian Ann. Med. Sc., Calcutta, 1873, vol. xvi. p. 594; Mignot, These de Paris, 
1851; Wurster, Beri. klin. Wehnschr., 1869, Bd. vi. S. 87; Andral, Compt. rend. Acad. 
d. sc., Paris, 1870, p. 815; Roger, Arch. gén. de méd., Paris, Sér. 4, tome v. p. 278; ‘‘De 
la temperature chez les enfants,” Paris, 1844 ; Lépine, Gaz. méd. de Paris, 1870 ; Fehling, 
Arch. f. Gynack., Berlin, 1874, Bd. vi. S. 385. 


INFLUENCE OF AGE. 805 


The average temperature falls one- or two-tenths from infancy to 
puberty, and about the same amount from puberty to middle age; after 
that stage is reached the temperature rises, and about the eightieth 
year is almost as high as in infancy.' According to Ringer and Stuart,? 
the average daily maximum in persons under 25 years is 37°'2 (99°), in 
those over 40 years, 37°1 (98°'8). 

As regards the temperature in old age, all observers seem to agree 
that it is equal to or slightly above that of adults. Davy* found the 
mean temperature of eight healthy old persons, with an average age of 
88, to be 36°-9 (98°45) in the mouth. Charcot* states, as the result 
of numerous determinations, that the rectal temperature in the aged 
is 37°2 to 37°°5, and is rarely higher or lower than in the adult; but 
the temperature in the well-closed axilla is often two or three degrees 
below that in the rectum, on account of the small and feeble circulation 
in the skin of the aged. Mossé and Ducamp® have compared the 
temperature of the axilla and rectum of aged people, and have obtained 
the following results; each figure represents the mean of twelve or 
fifteen observations :— 


| MORNING TEMPERATURE. EVENING TEMPERATURE. 

| Age 

| Axilla. Rectum. Axilla. Rectum. 

| 

75 36°40 =| 36°°83 36°°58 37°°04 

| 76 36°-48 37°-06 36°°41 36°-86 
80 36°08 | 36°46 36°40 36°°94 


The results obtained by Roger® upon seven healthy people, whose 
ages ranged between 72 and 95 years, are, for the mean temperature, 
36°68 and 36°23; for the minimum 36° and 35°°5, for the maximum 
37°10 and 37°, in the axilla and mouth respectively. 


In the case of young animals born in an advanced condition of develop- 
ment, the temperature is generally higher than that of the parents. Thus 
foals and calves, several hours after birth, have a temperature 0°'5 to 1° above 
that of their mothers. The average temperature of foals for the first five 
days is 39°-3, and then gradually falls, as shown by the table on p. 806, which 
represents the results of six hundred observations made by Fohringer’ upon 
one hundred horses. 

Similar results as regards the effect of age in horses were obtained by 
Siedamgrotzky,’ and in the case of cows and sheep by Hobday.® 


1 Wunderlich, ‘‘ Medical Thermometry”; Birensprung, Arch. f. Anat., Physiol. wu. 
wissensch. Med., 1851, S. 148. 

2 Proc. Roy. Soc. London, 1877, vol. xxvi. p. 194. 

3 Phil. Trans., London, 1844, pt. 1, p. 59; ‘‘Researches,” London, 1839, vol. iii. 

pra: 

: 4 Gaz. hebd. de méd., Paris, 1869, tome vi. p. 324. 

5 Gaz. hebd. d. sc. méd. de Montpellier, 1886. 

6 Arch. gén. de méd., Paris, Sér. 4, tome v. p. 273. 

7 Ellenberger, ‘‘ Vergleichende Physiologie der Haussiiugethiere,”” 1892, Bd. ii. Th. 2, 
S. 81. 

8 Deutsche Ztschr. f. Thiermed., Leipzig, 1875, Bd. i. S. 87. 

9 Journ. Comp. Path. and Therap., Edinburgh and Londen, 1896, Bd. ix. p. 286. 


806 ANIMAL HEAT. 


| Age. | In the Stables. Age. In the Fields. | 
4-6 years | 38°°05 4-6 years 37°°40 | 
eae EBON, Ss. stelgn | 6-12, 37°-24-37°49 | 
| 8-18, 37°85 12-18 ,, 37°48 | 


The influence of muscular work.—During muscular work there is 
an increased production of heat, and were it not for the compensation 
brought about by the increased loss of heat the temperature of the body 
would rise considerably. The effect, therefore, of muscular work upon the 
mean temperature varies according to the perfection of the compensation. 
Jiirgensen! found that the work involved in sawing wood for six hours 
raised the temperature of a healthy man 1°-2 above the normal, but 
as soon as the work was finished the temperature fell rapidly. Davy? 
made numerous observations upon the effect of active exercise on his 
own temperature. The highest readings of the thermometer under the 
tongue were 37°°5 (99°°5) and 37°°8 (100°); some previous observations 
upon the temperature of men after walking two or three hours showed 
a rise of ‘8° in the temperature of the urine, but no change in that 
taken in the mouth; after a rest the temperature rapidly fell to the 
normal. Alpine climbing, even on cold days, was found by Clifford 
Allbutt *® to raise the temperature of the mouth about half a degree; 
the same form of exercise was taken by Liebermeister and Hoffmann,* 
who observed the temperature in the axilla during both the ascent and 
descent ; the chief results were as follows :— 


Liebermeister’s temperature, 36°°82 before ascent and 37°°85 maximum during ascent. 


Hoffmann’s ‘5 36-250)" s, = 3 Bo 3 53 Ss 
Liebermeister’s . 36°°60 ,, descent ,, 37°°60 ob », descent. 
Hoffmann’s 2? 36°°40 2? 2) re 37°°25 ? ” ”? 


Results directly opposed to the above have been obtained by Lortet,* 
whose observations were made on level ground and during two ascents of 
Mont Blane (4810 metres high) in August 1869. On level ground Lortet 
found that, when he was at rest, the temperature of his mouth was 36°-4, 
but 36°°2 during bodily exercise. During the ascents of Mont Blane the 
temperature fell progressively and even reached as low a point as 31°8, but 
after a few minutes’ rest it rapidly reached the normal. Lortet explained 
these results by saying that during work the chemical forces which would 
have sufficed in the rarefied atmosphere to maintain the normal temperature 
of the body, were partly resolved in motion, and therefore the temperature 
fell. These results have been criticised by Clifford Allbutt and Liebermeister, 
and there can be little doubt but that the low temperatures observed were 
due to the cooling of the thermometer in the mouth by the laboured breathing 
of the cold air, which was sometimes several degrees below zero. This criticism ® 


1 “ Die Koérperwirme des gesunden Menschen,” Leipzig, 1873, S. 43-46. 

* Phil. Trans., London, 1844, pt. 1, p. 62; 1845, pt. 2, p. 322; 1850, p. 440. 

* Journ. Anat. and Physiol., London, 1872, vol. vii. p. 106. 

* Liebermeister, ‘‘ Handbuch der Path. u. Therap. des Fiebers,” 1875, S. 84. 

5 Compt. rend. Acad. d. sc., Paris, 1869 p- 709: 

° These sources of error have been shown to exist, for Arkle (experiments made at the 
request of the writer, and the results of which will be published later), during mountain 
climbing in the summer of 1897, found a constant rise of two or three degrees in the 
rectal temperature, but the meuth gave a low temperature. In fact, it was impossible to 
obtain accurate results by placing the thermometer in the mouth. 


INFLUENCE OF MENTAL WORK. 807 


is further supported by the fact that Lortet found a few minutes’ rest sufficient 
to raise the temperature to the normal. 

Marcet,! shortly before Lortet’s observations, found that during an ascent of 
some of the Mont Blane chain of mountains the temperature of his mouth fell, 
This result was contested by Vernet, who had determined the rectal tempera- 
ture under similar circumstances, and, as the result of the controversy, Marcet 
and Vernet”? in 1888 ascended together one of the highest points of the Jura. 
They found that there was a distinct rise in the rectal temperature. Marcet, 
however, does not look upon this result as conclusive ; he attempts to explain 
the rise of temperature as due to congestion of the hemorrhoidal vessels. It 
must be pointed out, however, that the increased circulation due to exercise 
would probably not cause congestion, and, whether it did or not, the rise in 
the temperature of the rectum indicates a rise in the temperature of the 
internal parts of the body. Further, Marcet himself shows that cooling the 
under surface of the chin causes a fall in the temperature of the mouth, and 
this was probably the cause of the low readings observed in his first ascents. 


Obernier? found that a walk for thirty-five minutes, when the 
external temperature was 11°°2, raised the rectal temperature from 37° 
to 38°. A walk of five miles raised the temperature of Ogle’s mouth 
from 37° to 37°°45.4| Similar results have been obtained by others.? 

Similar results to the above have been obtained upon animals. The 
temperature of a dog during the first hour of work upon a treadmill was 
raised 1°°8, but although the work was continued the temperature quickly 
fell (U. Mosso).6 In the case of two stallions three years old, Liska® found 
the temperature before work 37°8 and 38°0 respectively; after 
fifteen minutes’ work, 39°°5 and 39°; and again, after twenty minutes’ 
rest, 37°7 and 38°. Siedamgrotzky’ found that exercise raised the 
temperature of horses by an amount varying from 0°3 to 1°, while 
Hobday ® found in the case of healthy omnibus horses that the rectal 
temperature was generally raised 2° or more by hard work, and in sheep 
and pigs the exertion of running caused a similar rise in temperature. 

Further details of the production of heat in muscle will be given 
later. 


In the case of insects the effect of muscular activity is very marked. 
Thus Newport ? found the temperature of the abdomen of a very active humble- 
bee (Bombus terrestris) to be 23°, when the air was 19°-3 ; four of these active 
bees placed in a glass bottle raised the temperature of the air from 19°°3 to 
23°°6. 


The influence of mental work.—Mental activity is said to have an 
effect both upon the general temperature of the body and upon the local 
temperature of the brain and head. Thus Davy? found that mental 


1 Arch. d. sc. phys. et nat., Geneve, tome xxxvi. p. 247. 

2 Marcet, Croonian Lectures, Brit. Med. Journ., London, 1895, vol. i. p. 1367. 

3 ‘‘Ter Hitzschlag,” Bonn, 1867, S. 80. 

4 St. George's Hosp. Rep., London, 1866, vol. i. p. 232. 

5 Crombie, Indian Ann. Med. Sc., Calcutta, 1873, vol. xvi. p. 579; Roger, ‘“ Re- 
cherches cliniques sur les maladies de l’enfance,” tome i. p. 227 ; Speck, Arch. d. Ver. f. 
gemeinsch. Arb. z. Ford. d. wissensch. Heilk., Gottingen 1862, Bd. vi..S. 161-324; Cuny 
Bouvier, Arch. f. d. ges. Physiol., Bonn, 1869, Bd. ii. S. 386. 

6 Ellenberger, ‘‘ Vergleichende Physiologie der Haussiugethiere,” 1892, Bd. ii. Th. 2, 
S. 87. 

7 Deutsche Ztschr. f. Thiermed., Leipzig, 1875, Bd. i. S. 87. 

8 Journ. Comp. Path. and Therap., Edin. and London, 1896, vol. ix. p. 286. 

9 Phil. Trans., London 1837, pt. 2, p. 259. 

10 [bid., 1845, pt. 2, p. 319; 1850, p. 443. 


808 ANIMAL HEAT. 


work in England and in the tropics raised his temperature 0°27 and 
1°-1 respectively, and an increase varying from 01 to 0°7 has been 
observed after similar exertion by Speck, Rumpf,? and Gley*; the 
temperature was taken in the rectum, axilla, or mouth. Clifford 
Allbutt,t however, in a long series of observations, found that mental 
work had no effect upon the temperature. 

Cavazzani® states that in the case of a man whose skull had been 
trephined over the right temporo-occipital region, a thermometer placed 
in the dura mater showed a rise of two-tenths of a degree during mental 
activity. A. Mosso® maintains that intense psychical processes may 
cause so much heat to be set free in the brain that its temperature may 
remain for some time 0°:2 to 0°°3 above the temperature of the rectum. 
In a curarised dog the action of cocaine may produce a rise of as much 
as 4° in the temperature of the brain (37° to 41°). In man, Lombard? 
found that mental activity caused a slight rise in the temperature of the 
head, especially in the occipital region. 

It is probable, however, that this local rise of temperature is not due, 
as Mosso believes, to very active combustion in the ganglion cells, but to 
vascular changes consequent upon the mental activity. Hill and 
Nabarro’ have shown that the blood from the venous sinuses of the 
skull is less venous in colour than that of the femoral vein, that the 
metabolism of the brain is very low, and that it is scarcely increased 
during an epileptic fit. The average differences between the gases 
in samples of blood from the carotid artery and from the torcular 
Herophili of dogs were as follows :— 


NORMAL. Tonic Fir. Conic Fit. 


Art. Tore. Diff. Art. Tore. Diff. Art. Tore. Diff. 


Carbon dioxide | 40°86 | 44°74 | +3°87] 44°98 | 49°04 | +4°06| 30°59 | 33°58 | +2°99 


Oxygen . . | 16°81 | 13°39 | —3°42) 15-17 | 10:22 | —4°95| 15°77 | 11°46 | —4°51 


It is probable, therefore, that the temperature of the brain is not 
perceptibly greater than that of the blood. The cerebral circulation 
changes passively with every alteration of the general arterial or venous 
blood pressure,’ and this is apparently the explanation of Lombard and 
Mosso’s results. Moreover, the experiments of Helmholtz,!° Heiden- 
hain," and Rolleston ” have failed to demonstrate the formation of heat 
in nerve. 


1 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1882, Bd. xv. 

* Arch. f. d. ges. Physiol., Bonn, 1884, Bd. xxxiii. S. 601. 

* Compt. rend. Soc. de biol., Paris, 1884, p. 265. 

+ Note communicated to the writer. 

° Arch. ital. de biol., Turin, 1893, tome xviii. p. 328. 

6 Proc. Roy. Soc. London, 1892, vol. li. p. 83; ‘‘Die Temperature des Gehirns,” 
Leipzig, 1894. 

* Arch. de physiol. norm. et path., Paris, 1868, tome i. p. 670. 

8 Journ. Physiol., Cambridge and London, 1895, vol. xviii. p. 218. 

° Roy and Sherrington, ibid., 1890, vol. xi. p. 85; Hill, ibid., 1895, vol. xviii. p. 15. 

1 Arch. f. Anat., Physiol. u. wissensch. Med., 1848, S. 158. 

1 Stud. d. physiol. Inst. zu Breslau, Leipzig, 1868, Bd. iv. S. 250. 

® Journ. Physiol., Cambridge and London, 1890, vol. xi. p. 208. 


INFLUENCE OF FOOD. 809 


The influence of food.—tThe investigations of many observers + show 
that the effect of food upon the temperature of the body is to cause a slight 
rise, or, in the case of the evening meals, to postpone for a short time 
the customary fall of temperature at that time. The rise is often in- 
appreciable and rarely exceeds half a degree; the maximal effect is 
seen about one hour and a half after the meal. A draught of cold water 
(10°) lowers the temperature about half a degree? 

In the case of the horse the effect of food is to cause a rise of 0°2 
to 0°-8, which persists for three or four hours. 

Maurel® states that in the rabbit food is the chief cause of the daily 
variation in temperature, for if the animal be kept without food during 
the day but be fed during the night, the temperature shows a rise to the 
maximum, not at the usual time, in the evening, but in the morning. 
This is denied by Carter, who observed an evening rise in the tempera- 
ture of rabbits which had fasted three days. 

Bernard ® determined the temperature of the blood of the portal and 
hepatic veins under different conditions as regards the nutrition of the 
animals, and came to the conclusion that more heat was produced in the 
liver during digestion. The following are some of his results :— 


Blood of Portal | Blood of Hepatic | Blood of Right 
Vein. Vein. Side of Heart. 


Dog—After fasting for four days . 37°°8 B8°"4 38°°8 
» Beginning of digestion . “ov 39°°9 39°°5 
»  Infulldigestion . : . 39° 7 41°°3 39°°2 


The effect of starvation upon the temperature of animals has been 
studied chiefly by Chossat,® and Bidder and Schmidt.’ The first observer 
made experiments on twelve pigeons, and he found that the rectal 
temperature gradually fell until a short time before death; during the 
period of inanition the daily variation in temperature became more 
marked, and towards the end of life a rapid fall in temperature occurred. 
The results are shown in the table on p. 810. 

On the day of death the temperature of the pigeon fell to 26°2. 
Similar experiments on turtle-doves, hens, rooks, rabbits, and guinea- 
pigs gave the following temperatures:—22°'9, 28°2, 34°°3, 27°-0, and 23°°9 
respectively on the day of death. 

Bidder and Schmidt experimented upon a cat, and found that after 


1Davy, Phil. Trans., London, 1845, pt. 2, p. 319; ibid., 1850, p. 444; Damrosch, 
Deutsche Klinik, Berlin, 1853, S. 317 ; Jiirgensen, ‘‘ Kérperwirme des gesunden Menschen,” 
Leipzig, 1873, S. 21; Deutsches Arch. f. klin. Med., Leipzig, 1867, Bd. iii. 8. 165 ; 
Ringer and Stuart, Proc. Roy. Soc. London, 1877, vol. xxvi. p. 194; Ogle, St. George's 
Hosp. Rep., London, 1866, vol. i.; Crombie, Indian Ann. Med. Sc., Calcutta, 1873, vol. 
xvi. p. 581. 

2 Liebermeister, ‘‘ Handbuch d. Path. u. Therap. des Fiebers,” Leipzig, 1875, S. 123 ; 
Wunderlich, ‘‘ Medical Thermometry”; Siedamgrotzky, Deutsche Ztschr. f. Thiermed., 
Leipzig, 1875, Bd. i. S. 87. 

Compt. rend. Soc. de biol., Paris, 1884, p. 588. 

4 Journ. Nerv. and Ment. Dis., N.Y., 1890, vol. xvii. p. 785. 

5 «<Tecons sur la chaleur animale,” Paris, 1876. 

6 «*Recherches expérimentales sur l’inanition,” Paris, 1843, quoted from Gavarret, 
“* De la chaleur ete.,”’ p. 394. 

7 «Die Verdauungssifte und der Stoffwechsel,”’ Leipzig, 1852, S. 322. 


810 ANIMAL HEAT. 


355 hours’ hunger the rectal temperature fell from 39°08 to 38°4; after 
369 hours, to 38°1; after 393, to 35°°5; after 415 hours, to 33°7; and 
again, after 426 hours, to 32°°4, when the animal died. 


RECTAL TEMPERATURE. 
| DAILy VARIATION, 
Midday. | Midnight. 
Normal pigeons. : : th 42°°22 | 41°-48 | 0°-74 
Complete inanition, first period aru 42°°1 39°°8 2°°3 
| 
| 
hy a4 second ,, th) 41°°9 38°°7 39:2 
a 45 third ;, aa 41°*4 37°°3 4°] 


In the case of the fasting man Tanner,! no fall in temperature was 
observed after thirty days’ fast; the temperature of his mouth was 
36°°9 (98°-4) on the twenty-fifth day, and 37°1 (98°°8) on the thirtieth 
day. It is uncertain whether the fast was perfectly genuine, for Tanner 
took a certain amount of liquid. Noyes? recorded a temperature of 
34°-4 (94°) in the case of a partly demented man, who had taken no food 
for forty-five days, but it is to be noted that the condition was compli- 
cated by paralysis of the lower limbs. 

The influence of sleep.—The heat of the body falls during the night 
and early morning, the time of inactivity and rest, but, according to 
Barensprung? and Wunderlich,? sleep in itself has no influence on the 
temperature. Crombie,° on the other hand, found that sleep during the 
day caused a fall in temperature of about half a degree, but was 
rapidly followed by a rise after awaking. Hunter® found that during 
sleep the temperature fell about eight-tenths of a degree. ‘The observa- 
tions of Jiirgensen and Liebermeister’ show that the temperature of a 
man asleep is not lower than his temperature at a similar time of day 
when he is awake and lying still. Inactivity causes a fall in temperature, 
and sleep is a condition in which inactivity is most marked. Lieber- 
meister § found that, by contracting the habit of sleeping each afternoon 
for ten days, the mean temperature of his axilla fell to about 365, 
whereas it had previously been for that time of day 37°°3. Observations 
by U. Mosso ® also show that sleep during the daytime causes a fall in 
the rectal temperature of man. 

The influence of sex.—Very little difference in temperature can 
be observed in the two sexes? Women may have a slightly higher 
temperature, but the difference does not exceed half a degree; their 
temperature, however, appears to be more liable to variations. Davy ™ 


1 Brit. Med. Journ., London, 1880, vol. ii. p. 171. 2 1bids, Pmoola 

3 Arch. f. Anat., Physiol. u. wissensch. Med., 1851, S. 163. 

4“ Medical Thermometry,” p. 109. 

> Loc. cit., p. 585. 

§ Phil. Trans., London, 1778, vol. lxviii. pt. 1, p. 20; ‘* Works,” Palmer's edition, 
London, 1887, vol. iv. p. 144. 

7 Liebermeister, ‘‘ Handbuch d, Path. u. Therap. des Fiebers,’’ 1875, S. 87. 

8 Ibid., S. 92. 

® Arch. ital. de biol., Turin, 1887, tome viii. p. 177. See also this article, p. 802. 

10 Wunderlich, ‘‘ Medical Thermometry.” 

1 Med. Times and Gaz., London, 1864, vol. ii. p. 337. 


INFLUENCE OF RACE. 811 


concluded that the temperature of women and female animals was lower 
than that of the male, but his observations were made upon only three 
or four individuals. Thus he states that the temperature of three 
healthy men varied between 37°°2 and 37°5, that of three women 
between 36°°5 and 36°°7 ; in the case of three cocks and three hens the 
results were 42°4 and 42°:1 respectively. Bérensprung+ found no 
marked difference, the average temperature of eighteen women being 
37°25. As the result of seventy or eighty observations, Siedamgrotzky # 
gives the temperature of stallions, mares, and geldings as 37°°8, 38°:2, 
and 58°05 respectively ; the average temperature of a large number of 
ducks was found by Martins® to be 41°96 for the male, and 42°27 for 
the female. Singleton ‘+ determined the rectal temperature of fifty dogs 
and of fifty bitches; the average for the former was 58°°9, for the latter 
08°'7. The observations were made at similar times of the day, but 
upon animals of different breeds. 

The influence of: race.—The natives of tropical countries appear to 
have a temperature slightly higher than that observed in the inhabitants 
of mild or cold climates, but the difference is to be ascribed mainly to 
the climate. Davy,> from observations made upon natives in the 
Cape of Good Hope, Isle of France, and Ceylon, found the temperature 
to be about 0°6 higher than the average in temperate climates; 
Crombie® made fifty-two observations on Hindus, Mohammedans, and 
East Indians in Bengal, and found that the average temperature from 
10 a.m. to 10 P.M. was between 37°°2 and 37°8, that from 10 P.M. to 
10 a.m. between 36°°7 and 37°°2. Both of these observers also found 
that the temperature of Europeans living in the same district was about 
half a degree higher than the average in England. Jousset? made 
numerous observations on natives and Europeans living in tropical 
climates, and came to the conclusion that the axillary temperature is 
generally 0°'7 to 0°8 higher than that observed in temperate climates. 
The following figures show that climate, and not race, is the important 
factor :— 


| Natives of Tropics. Europeans. 
Hindus. : - 37°°85 Officials at Chandernagore . 38°'16 
Cochin-Chinese . : 37°°60 } 
Chinese . f : 37°85 | 
Negroes of Senegal. 37°°70 ~=—| + Sailors at Senegal ‘ ‘ 37°°75 
- Congo : 37°°80 aE Antilles ’ iN 9ooes70 
Antilles. 37°°80 Soldiers at ,, . NO ay ty) 


| 2? 


Similar results to the above were obtained by Maurel.® 
The temperature of natives in South Africa was found by Livingstone ® 
to be 36°°7, when the temperature of the air in the shade was 42°2, 


1 Arch. f. Anat., Physiol. u. wissensch. Med., 1851, S. 155. 

2 Deutsche Ztschr. f. Thiermed., Leipzig, 1875, Bd. i. S. 87. 

3 Ellenberger, ‘‘Vergleichende Physiol. der Haussiiugethiere,” 1892, Bd. ii. Th. 2, 
S. 85. 

4 See p. 790. 

5 <* Researches,” London, 1839, vol. i. p. 169. 

8 Indian Ann. Med. Sc., Calcutta, 1873, vol. xvi. p. 591. 

7 Arch. de méd. nav., Paris, 1883, tome xl. pp. 123, 426. 

8 Bull. Soc. danthrop. de Paris, 1884, tome vil. p. 380. 

9 «Travels and Researches in South Africa,” 1857, p. 509. 


812 ANIMAL HEAT. 


but his own temperature was 37°°8, owing probably to the difference in 
clothes. Thomson! found the mean temperature of natives in Iceland 
to be 37°27, and Kijkman ? states that the average temperature of 
Europeans living in Batavia is 37°02, that of the Malays 36°93. 

The een of a eeason and pregnancy.*—Normal men- 
struation and pregnancy in healthy women have no marked influence 
upon the general temperature of the body. During labour the temper- 
ature rises somewhat during the pains, but falls again between the pains. 
Immediately after delivery a slight fall in temperature occurs. 

Individual peculiarities in temperature.—Observations on men, 
and especially on animals, show that the mean temperature of different 
individuals is not the same, even when the conditions are as far as 
possible equal. The mean temperature in the axilla of different men 
may vary from 36°5 (97°7) to 37°25 (99°05). In animals even 
greater differences are found.’ 

The influence of the temperature of the surroundings. —The 
temperature of man and other warm-blooded animals is only slightly 
influenced by the temperature of their surroundings. This fact is well 
shown by the records of the temperature of men “and animals in the 
tropics and Arctic regions, w here the extremes of the temperature of 
the air occur, in the former +59°C., in the latter — 55°C. During a 
voyage from England to Ceylon, Davy® made observations upon the 
temperatures of seven healthy men under 30 years of age: he found 
that the average temperature under the tongue was about 36°-9 (98°:4) 
when the temperature of the air was 15°6 (60°), and 37°32 (99°2) 
when the air was 26°-4 (79°5). From these and other observations,’ 
he concluded that the temperature of man increases in passing 
from a temperate into a warm climate, and that the inhabitants of 
warm climates have a slightly higher temperature than those of 
mild climates. Reynaud and Blosville’ found the mean temperature 
of eight men to be 37°58 (100°), when under the torrid zone, 
the temperature of the air varying from 26° to 30° (79°—86°), and 
Silt (992) im the temperate zone, with an external temperature 
varying from 12° to 17° (53°-62°). pie average temperature of the 
mouth was found by LET ® to be 37°25 (99°) i in the tropics, with an 
external temperature of 25°, as compared with 56°°8 (98°35), the average 
temperature in England during the summer heat (18°). 

These and further observations, made by Brown-Séquard and others,! 


1 “¢ Ueber Krankheiten und Krankheitsverhiltnisse auf Island,’’ Schleswig, 1855, S. 24. 

2 Virchow’s Archiv, 1895, Bd. exl. S. 125. 

* Numerous references on this subject will be found in Wunderlich’s ‘‘ Medical Ther- 
mometry,” ew. Syd. Soc. Translation, p. 105. See also Birensprung, Arch. 7. Anat., 
Physiol., wu. wissensch. Med., 1851, S. 157 ; Probyn Williams and Lennard Cutler, Lancet, 
London, 1895, vol. i. p. 932; Giles, Brit. Med. Journ., London, 1894, vol. ii. p. 70. As 
regards animals, see Hobday, Veterinary Rec., London, 1896, vol. viii. p. 488. 

4 This article. p. 789. 

° This article, P. 790. 

6 “Researches,” London; 1839, vol. i. p. 161. 

7 Phil. Trans., London, 1850, p. 437. 

8 ** Animal Heat, ” article by ‘Edwards in Todd’s “ Cyclopedia,” vol. il. p. 659. 

* Proc. Roy. Soc. London, 1870, vol. xviii. p. 526. 

0 Brown-Séquard, Journ. de ta physiol. de Vhomme, Paris, 1859, tome ii. p. 152 ; Gress- 
well, Brit. Med. Journ., London, 1884, vol. ii. p. 164 ; Mantegazza, Presse méd. belge, 
Bruxelles, 1863, tome xv. p- Ts Maurel, Bull. Soc. @ anthrop. “de Paris, 1884, tome vil. 
p: 371; Jousset, Arch. de méd. nav., Paris, 1883, tome xl. p. 124; Pinkerton, Journ. 
Anat. and Physiol., London, 1881, vol. xy. p. 118; Edoux and Souleyet, Compt. rend. 
Acad. d. sc., Paris, 1838 tome vi. p. 456. 


INFLUENCE OF EXTERNAL TEMPERATURE. 813 


show that the effect of tropical heat is to raise the mean temperature 
of the human body, but the increase is generally less than one degree. 
Crombie! found, as the result of 1288 observations upon himself, that 
the temperature of the mouth was about 0°23 higher in Bengal than the 
average in England, but the difference was greater during the first few 
weeks of residence in the hot climate. ‘ 

On the other hand, some observers maintain that residence in a 
tropical climate does not raise the temperature of the body; thus 
Boileau? states that the normal axillary temperature is between 36°7 
and 37°2, Thornley? and Furnell* that it is invariably the same as in 
England, 36°°9. 


Numerous careful observations recently made by Neuhauss® during a 
voyage round the world, show the effect of external heat upon the daily 
temperature, pulse, and discharge of urine. The following are some of the 
results :— . 


| 


, 
7S =e te sue Ten P.M. | Six P.M. | REMARKS. 
j | 
| TEMPERATE 
ZONE. 
Min. | Max. | , 
11°5 |13°6 | 36°6 | 36°9 | 3678 | 37°1 | Temperature ity gd BOE 
/ rectum Hits y 
55 55 56 | 62 | Pulse a 
TROPICAL ZONE. | 
23°°9 | 26°°6 | 36°°9 | 37°°3 | 37°-1 | 37°°3 | Temperature in 
ie sechran | se a twenty- | 
— 60 68 | 64 72 | Pulse ji Se 
| ] | 
| 


The influence of the different seasons of the year.—No marked 
effect upon the heat of the body can be ascribed to the different seasons 
of the year, apart from that due to variations in external temperature. 
The numerous observations made by Davy® upon hinself tend to show 
that the temperature of the mouth is somewhat lower during the winter 
months in England, and slightly higher during the summer; a similar 
series taken in the tropics, in Barbadoes, where the mean annual 
temperature of the air is 26°7, and the range throughout the year is 
about 8°, shows no marked variation during the different seasons. 

Jousset’ found that the cool season caused a fall of two- or three- 
tenths of a degree in the average temperature of natives of the tropics. 

From Bosanquet’s ® observations of the rectal temperature, it appears 
that the highest sustained average temperature occurred in the winter 
and early spring months. These determinations were made upon 
himself four times a day for a period of three years. 

A few observations have been made on the influence of winter and 
summer upon the temperature of animals. Thus Edwards® found in 
the case of sparrows that the mean temperature rose progressively from 


1 Indian Ann. Med. Sc., Calceutta, 1873, vol. xvi. p. 550. 

2 Lancet, London, 1878, vol. i. p. 413. 

3 Thid., 1878, vol. i. p. 554. 4 Thid., 1878, vol. ii. p. 110. 
5 Virchow’s Archiv, 1893, Bd. exxxiy. S. 365. 

6 Phil. Trans., London, 1845, pt. 2, p. 319; and 1850, p. 437. 

7 Arch. de méd. nav., Paris, 1883, tome xl. p. 124. 

8 Lancet, London, 1895, vol. i. p. 672. 

9 «* Animal Heat,” in Todd’s ‘‘ Cyclopedia,” vol. ii. p. 659. 


814 ANIMAL HEAT. 


the depth of winter to the height of summer; in the month of February 
the mean temperature was 40°°8, in April 42°, and in July 43°-77 ; from 
this time the temperature began to decline. It was also found that, in 
winter, birds could more readily resist the action of extreme cold than 
in summer. 

Davy! observed the temperature of sheep during summer and 
winter, and his results, although they are not sufficiently consistent 
for positive conclusions, seem to show that the temperature of the body 
is a little higher in the warm weather than in the cold. 

The influence of extreme heat and cold—The experience of 
the inhabitants of tropical climates shows that it is possible to live even 
in an atmosphere the temperature of which at times exceeds that of the 
body, and that the body is able, by means of the cooling effect of the 
evaporation of sweat, to prevent its temperature rising a degree above 
the normal. 

Lining? in 1738, found that the temperature of his axilla was 36°'1, 
and that of his mouth 36°°7, when the heat in the sun’s rays was 51°'1, 
in the shade 36°°7, on a hot summer's day in South Carolina. Ellis? in 
1758, observed that the temperature of his body was not above 36° 1 
when he was living in Georgia, and the temperature of the air was 
40°-6. Experiments on men and on lower animals have shown that much 
greater heat can be borne for short periods. Blagden and Fordyce * 
observed their own temperatures after remaining in heated rooms, and 
found that the effect varied according to the amount of moisture 
present; thus, after remaining fifteen minutes in a damp room heated 
to 54°-4, the temperature of the mouth and urine was 37°8, but a 
similar exposure in a dry room heated to 115*5—126°-7, and in which 
beefsteaks were being cooked by the heat of the air, did not raise the 
temperature of the body above the normal. Similar experiments were 
made by Dobson,? who found that the temperature in the mouth of one 
man rose to 37°°5 after he had remained about fifteen minutes in a 
room heated to 94°-4; in another case the rise was to 38°6, after 
twenty minutes’ exposure to air at 98°-9; and in a third case a stay of 
ten minutes in a room at 106°°7 caused a rise to 58°°9. 

Tillet ® had previously observed young girls remain without 
any inconvenience for five or ten minutes in a kiln heated to about 
130,° but he does not give any records of their temperature. In 1747, 
Le Monnier? found that he could remain for eight minutes in a bath 
supplied by a thermal spring, the temperature of which was 44° to 45°; 
at the end of that time his skin was red and swollen, and his distress so 
great that he was obliged to get out. No observations upon the 
temperature of the body are given. Kurrer® and Neuhauss ® have ob- 
served that the temperature of stokers, working in a stoke-hole at 50° 
to 56°, is raised to 37°°6, or even to 38°1. 

Numerous experiments have been made to determine the effect of 

1 «* Researches,” London, 1839, vol. i. p. 208. 

2 Phil. Trans., London, 1748, vol. xlv. p. 338. 

Sind., 17585 volalo tac, p. 754: 

4 Tbid., 1775, vol. lxv. pt. 1, pp. 111 and 484. 

5 Tbid., 1775, vol. lxv. pt. 2, p. 463. 

§ Hist. Acad. roy. d. sc., Paris, 1764, p. 188. 

TTbid., V747, p. 201. 

8 Deutsche Vrtljschr. f. ff. Gsndhtspflg., Braunschweig, (2), Bd. xxiv. S. 291. 
9 Virchow's Archiv, 1893, Bd. exxxiv. S. 365. 

0 See also Crombie, Jndian Ann. Med. Sc., Calcutta, 1873, vol. xvi. p. 601. 


INFLUENCE OF EXTREME HEAT AND COLD. 815 


extreme heat upon animals. Provoost and Fahrenheit, working under 
the direction of Boerhaave,' found that a dog and a cat placed in a hot 
stove (63°) died in twenty-eight minutes, whilst a sparrow, under 
similar conditions, died in seven minutes. Duntze? observed that 
dogs could live in an atmosphere at 42°-2, but died when the 
temperature was raised to 45°. It was found by Delaroche? that 
cats, rabbits, pigeons, and various insects could remain for one 
hour in a temperature of 36° without fatal results; the most marked 
symptom was the greatly quickened respiration. When the tempera- 
ture was raised to 45° or 53°, the cat and rabbit died within two hours, 
the pigeon in one hour and twenty minutes, the most marked symptom 
being convulsions. A frog, under similar conditions, was alive at the 
end of two hours. The temperature of a rabbit exposed to a heat of 45° 
for one hour and forty minutes rose from 39°°7 to 43°°8. Exposure to 
moist heat quickly raised the temperature of animals, as shown in the 
following table:— — 


| ; | 
Animal. cape, |e atteng | Malet Hea eee | 
Rabbit . : ‘ : 39°°6 43° PP aisee7/ 55 minutes 
Guinea-pig . ‘ ; 38°°4 44°°2 40°°7 55 i 
penal 228 ze) a 41°°8 46°°9 bhp -aes9 Ao” Vet 
Frog. , : F Not stated 26° | i 2b°56 73 - 
ee a s 27°°8 | 27°92 ie 


The effect of dry and moist hot air upon different animals was 
determined by Bernard + in numerous experiments; some of the results 
are here given :— 


Animal. Dry Air. Death. Animal. Dry Air. Death. 
Pigeon . 4 90° | In6 minutes || Rabbit . : 100° | In 10 minutes 

| 5 : ; 90° 64 ,, ae : : 80° i Steen 

Mees. 90° i ai i pny, ey 80° ieee 

Guinea-pig. 100° 5 dal bar * . : 65° Zo he 

nF , 100° Gia HS Dog £ : 100° US) 3s 

Rabbit... 100° ron m j 90° ao 

Dog : : 100° iS ieee ah 80° Bi)" 5h 
Rabbit . : 100° hbase | | 


In moist hot air the animals died very quickly: thus, when the 
temperature was 80°, 60°, and 45°, the rabbits died in two, three, and 
ten minutes respectively. Experiments made by immersing the body 
of the animal in hot water gave similar results. To determine the effect 
of exposing the body to dry heat without warming the air used for 
respiration, Bernard made the following comparative experiments upon 
rabbits of similar size :— 


1 «*Praelect. Anat.,” p. 211; ‘‘Elém. de chymie,” tome i. pp. 148, 277, 278. 

2 Quoted from Delaroche (°). 

3 Journ. de phys., Paris, 1806, tome lxiii. pp. 207, 468 ; 1810, tome ]xxi. p. 289. 

4 Gaz. méd. de Paris, 1859, tome xiv. p. 462; ‘‘Lecons sur la chaleur animale,” 
1876, p. 349. 


816 ANIMAL HEAT. 
(a) Rabbit placed in dry air 100°— 
Temperature before 0 
# after 5 minutes = 41° 
n fe shO », = 44°—+respiration quickened. 


+ in okG Se eee 


(b) Head of rabbit placed in dry air 100°, body in cool air— 
Temperature before = 40° 


5j after 5 minutes = 40° 
ir eee 8) » = 40°—tespiration quickened. 
” ” 1D ” = 41° 
2 ? a Peeheeniy 738 respiration very rapid. 
” ”? tt ” Ps; 
” ” 30 ” = 43° 
- BA ier el i; = 4o ——deabne 
(c) Body of rabbit in dry air 100°, head in cool air— 
Temperature before — sooo 
: after 4 minutes = 42° 
a sovmegllil 5,  =43°—-respiration quickened. 
” ” 15 ” = 44° 
;; 3 20 5  =45°—death. 


Obernier! found that when the external temperature was first 
raised the rectal temperature of dogs and rabbits fell slightly, about 
0°-4, but soon after the air reached 30° to 35° the temperature of the 
animal began to rise. Death generally sealed before the internal 
temperature rose to 45°, but in one case it reached 46°-2. The most 
important symptoms were restlessness, quickening of respiration and 
pulse, and finally convulsions and loss of consciousness. A short time 
before death 1t was impossible to feel the pulse, a fact explained by the 
fibrillar contraction of the heart observed by Obernier when the thorax 
was opened. An examination of the body directly after death showed 
marked congestion of the brain and lungs; the muscles were inexcitable, 
and quickly went into rigor mortis. Similar changes were observed 
in the bodies of soldiers who had died from sunstroke. 

Numerous facts show that cold-blooded animals can live in hot 
media. Thus, internal parasites of mammals and birds can live in sur- 
roundings at temperatures of 57° and 43°-9; and there are well-authentic- 
ated cases of fishes living in springs as hot as 37°-44°2 Sonnerat® 
even states that he saw fish actively swimming about in the hot water 
(60°—62°) of thermal springs in New Guinea ; it is doubtful, however, 
if the temperature was correctly recorded in this case. 

It has been shown by Davenport and Castle*+ that by gradually 
raising the temperature tadpoles can be kept alive in warm water. 
Hertwig® has observed that no development takes place in the ova 
of the frog when the temperature of the water is zero, but between 
2° and 33° it progresses with different rapidity, cold delaying, warmth 
hastening the process. A temperature, however, of 34° is fatal. 


1 «* Der Hitzschlag,”’ Bonn, 1867. 

* Spallanzani, ‘*Opuse. de phys. anim.,” tome i. pp. 54— 69, 101; Desfontaines, quoted 
from Gavarret, ‘‘ De la chaleur produite pas les étres vivants,’ ’ Paris, 1855, p. 464; Tripier, 
Compt. rend. Acai. d. sc., Paris, tome ix. p. 602; Cumberland, Biblioth. univ,, Geneve, 
1839, tome xx. p. 204; Prinsep, ibid. 

3 « Voyage a la Nouvelle Guinée,” Paris, 1776, pp. 38-41. 

4 Arch. f. Anat. u. Entweklngsgesch., Leipzig, 1885, Bd. ii. S. 227. 

5 Sitzungsb. d. preuss. Akad. d. W issensch., 1896, S. 105. 


Ee 


INFLUENCE OF EXTREME HEAT AND COLD. 817 


Numerous observations show that the temperature of animals living 
in the Arctic regions is equal to that of animals of the same classes in 
temperate climates. The following are some of the results obtained by 
different explorers :— 


Temperature of Temperature of 


Animal. Aninial! ihe Observer. 
j | 
} | 38°°3 | -35°°6 Parry and Lyon.? 
Arctic fox . ; : | 41°", —35°'6 “e 
39°°4 —32°'8 » 
Wolf . a F x 40°°5 —32°°8 ” } 
White hare holier Ade 38°°3 -29°°4 9 | 
. Fil 3°°9 _19°°7 2 
Prairie fowl (male) $ {| or Gest iL | 
| 42°°8 | =P: | 
Prairie fowl (female) | 43°°3 —8°-0 ‘ 
‘ 42°°8 -1°'1 » 
i 42°*4 | -19°°7 si | 
Willow grouse (male) + 43°°3 —32°°8 5 
| 43°°3 -35°'8 2 


The limits of extreme cold are generally reached when the water in 
which the animals live, or the lymph of their tissues, is frozen. Fishes 
live in salt water when the temperature is below zero, but usually die 
when the water is frozen. 

Boyle*® exposed lampreys in a vessel of water to an exceedingly 
sharp frost, and found next day that one lamprey was frozen in the ice; 
when the ice was partly broken and partly thawed the animal was at first 
motionless, but in a few minutes recovered, and dragged after it a large 
piece of ice in which its tail was fixed. Similar experiments were made 
with similar results upon gudgeons and frogs. Hunter* found by 
experiment that the internal temperature of a frog and an eel could be 
reduced to —0°-6, and that, although the animals appeared to be dead, 
they revived when the temperature rose. Regnard® found that carp 
will live in water containing 2} per cent. of magnesium sulphate, 
even when the temperature is a degree or two below zero ; at —2° the fish 
appear to be asleep, and at —3” their vitality is so greatly reduced that 
they seem to be dead, but revive when the water is gradually warmed. 
Pictet® exhibited at one of his lectures frozen gold fish, pike, and 
frogs, and at the next lecture the same animals alive and well after 
gradual thawing. According to this observer, fishes can be rapidly 
frozen so hard that they can be snapped in two, and yet other fishes 
frozen equally hard recover when slowly thawed. It has been observed 
by Marcet® that gold fish completely embedded in the ice showed no 
signs of life on thawing, but one fish, which was partly encased in ice 
and was surrounded by a little water, appeared lifeless, but recovered 
perfectly in a short time. Observations and experiments made by 


1 Parry, ‘‘Journal of a Second Voyage for the Discovery of a North-West Passage,” 
London, 1824, p. 157; Ann. de chim. et phys., Paris, 1825, Sér. 2, tome xxviii. p, 223. 

2 Compt. rend. Acad. d. sc., Paris, 1836, tome ii. p. 621. 

3 «* Philosophical Works,” Shaw’s edition, vol. i. p. 688. 

+ “* Works,” Palmer’s edition, London, 1837, vol. iv. p. 131 et seq. 

> Compt. rend. Soc. de biol., Paris, 1895, p. 652. 

§ Quoted from Marcet, Croonian Lectures, Brit. Med. Jowrn., London, 1895, vol. i. 
p. 1367. 


VOL. I.—52 


818 ANIMAL HEAT. 


Gaymard! and Gavarret? show that toads and fishes may be frozen 
perfectly stiff and yet revive when gradually thawed ; according to the 
former observer, the freezing must be gradual, otherwise the animals are 
killed. During Franklin’s® explorations in the Arctic regions, it was 
observed that fish frozen completely hard recovered when they were 
thawed ; a carp, which had been frozen for thirty-six hours, was able 
after it was thawed to leap about with much vigour. 

The influence of baths.—A warm or cold bath has a greater effect 
upon the temperature of the body than exposure to air at the same 
temperature, for the power of conduction of water is greater than that 
of air. The first important experiments upon this subject were made 
by Currie in 1797.4 He found that the immediate effect of a cold bath 
might be a slight rise in the temperature of the mouth, but the per- 
manent effect was a fall. The following are some of his results :— 


| Temperature of Duration of Temperature before | Temperature after 


Bath. Bath. } the Bath. the Bath. 

| 

Sea water 6°°7 | 12 minutes | 36°°7 34°°0 
¥ 5:9.) 80 36°°3 34°°3 


Fresh water 4°°3| 34 ,, 36°°7 33° °7 


The temperature was taken in the mouth, and therefore the depres- 
sion was greater than it would have been in the rectum. 

Fleury ® found the temperature in the mouth sink to 34°, 32°-9, and 
even to 29° during a cold bath; Virchow® observed a fall to 34°; 
Speck? found that the immediate effect of a shower bath at 22° was 
to raise the temperature of the mouth, but after ten minutes’ exposure 
the temperature fell 1°-23. 

Numerous observations have been made by Liebermeister,? who 
selected the temperature of the closed axilla as representing more 
exactly the temperature of the body. He concludes that the immediate 
effect of a cold bath is to slightly raise the temperature, and that a bath 
of moderate cold and duration does not lower the temperature below 
the normal, for an increase in the heat production compensates for the 
increased loss. Liebermeister, as Currie had previously done, used the 
bath as a water calorimeter, and calculated that in a bath of from 20° 
to 30° the heat production was three or four times greater than the 
normal. Jiirgensen® confirmed many of these results; he found that 
the rectal temperature of men did not fall more than 1°, often less, after 
remaining twenty-five minutes in a cold bath at 11° to 9°. Recently 
Lefevre? has given excellent proofs of the power of regulation of 


1 Biblioth. univ., Geneve, 1840, tome xxvi. p. 207. 

= **De Ja chaleur produite par les étres vivants,” Paris, 1855, p. 502. 

3 Franklin, ‘‘ Journey to the Polar Sea,” 1819-1822, 2nd edition, vol. ii. p. 17. 

4 “Medical Reports on the Effect of Water, Cold and Warm, as a Remedy in Fever and 
other Diseases.” 

> Progrés med., Paris, 1858, p. 337. 6 Virchow’s Archiv, 1858, Bd. xv. S. 70. 

te rol d. Ver. f. gemeinsch. Arb. z. Ford. d. wissensch. Heilk., Gottingen, 1861, Bd. 
v. 8. 422. 

8 Arch. f. Anat. Physiol. wu. wissensch. Med., Leipzig, 1860, S. 520, 589; ‘‘ Handbuch 
d. Path. u. Therap. des Fiebers,” 1875, S. 102. 

° Deutsches Arch. f. klin. Med., Leipzig, 1867, Bd. iii. S. 165; Bd. iv. S, 110, 323. 


> 


19 Compt. rend. Soc. de biol., Paris, 1895, p. 559; 1896, pp. 492, 564. 


INFLUENCE OF BATHS. 819 


temperature in man. He remained three hours in a bath at 15°, and yet 
his axillary temperature fell only one degree (57°30 to 36°30 in the 
first two hours and a half, and then remained stationary at 36°30); the 
amount of heat lost was 800 kilo-calories. A bath in water at 25° for 
three hours caused a fall in temperature from 37°20 to 56°60, with a 
loss of 312 kilo-calories; while a bath of one hour’s duration in water at 
7° caused a fall from 37°°70 to 36°, the loss of heat being 530 kilo- 
calories. 

In comparing the effect of baths on different people, it is important 
to consider the size of the body and the amount of subcutaneous fat, 
for the greater the size and amount of fat the slower is the cooling of the 
body. Liebermeister found that the temperature of the axilla of a fat 
man only fell 0°2 during a bath of 21° to 30°, lasting one hour and a 
half. 

The effect of a warm bath is to raise the temperature, but after the 
bath there is, as Currie and Liebermeister observed, a fall in temperature 
followed by a gradual rise to the normal. 

It is impossible here to consider all the numerous results, some 
contradictory, which have been obtained by different observers! It is 
important, however, to note that the different results markedly show 
the power of compensation possessed by the higher animals. A cold 
bath abstracts a large quantity of heat, but within certain limits does 
not cause the temperature of the body to fall, for the cutaneous blood 
vessels contract and thus diminish the loss of heat, and the cold acting 
on the nervous system stimulates the tissues to increased production 
of heat; on the other hand, a hot bath would quickly cause a rise in 
temperature, if the animal were not able within certain limits to in- 
crease its loss of heat by an excessive vascularity of the skin and to 
diminish its production of heat. These compensating factors show their 
influence by a rise in temperature after a cold bath and by a fall after 
a hot bath, as the case may be. For this reason a hot bath is most 
effective in producing a cooling effect upon the body in tropical climates. 
The after-effects, however, soon disappear, and the temperature becomes 
normal. 

The compensation is, in fact, so exact in a healthy man, that any fall 
or rise in temperature, caused by too long exposure to cold or heat, is 
followed respectively by a rise above or fall below the normal. Thus it 
is that the mean daily temperature and the daily variations are very 
slightly or not at all affected by baths (Jiirgensen,? Liebermeister,* Ringer 
and Stuart,t and others). Still it must be remembered that this com- 
pensation is only effective within certain narrow limits,> and does not in 
any way invalidate the use of cold baths in the treatment of high 
temperatures in cases of fever. 

Experiments upon the influence of warm and cold baths have also 
been made upon animals, and the results agree with those obtained 
upon man. Crawford® in 1871 found that the temperature of a dog 
kept in a hot bath, 45°°6 to 44°-4, rose in thirty minutes to 42°°8, and 


1 For further details and references see Liebermeister, ‘‘ Handbuch d. Path. u. Therap. 
des Fiebers,” Leipzig, 1875 ; Wunderlich, ‘‘ Medical Thermometry,” p. 109. 

2 Loc. cit. 3 Loe. cit. 

4 Proc. Roy. Soc. London, 1877, vol. xxvi. p. 203. ) 

5 Lowy, Arch. f. d. ges. Physiol., Bonn, 1889, Bd. xlv. S. 625; 1890, Bd. xlvi. S. 
189; see also ‘‘ Chemistry of Respiration,” this Text-book, vol. i. p. 712. 

6 Phil. Trans., London, 1781, vol. lxxi. p. 486. 


820 ANIMAL HEAT. 


the dog became very languid; the venous blood of dogs kept in a warm 
bath had an arterial colour, whereas a cold bath, 7°:2, rendered the 
blood in the jugular vein very dark. More extended observations were 
made by Hoppe! upon both the immediate and after effects of baths 
upon dogs. The rectal temperature of a dog placed in water at 48° 
for three minutes rose from 38°°75 to 41°45; a cold bath at 9°12, 
lasting half a minute, caused a fall of 1°; a bath of freezing water, 
lasting respectively two and four minutes, produced a fall of 1°°7 and 
4°88 below the normal. Hoppe found that the temperature fell during 
a cold bath but afterwards rose above the normal, that it rose during 
a hot bath but afterwards fell below the normal. The sensation of 
cold stimulated the organism to an increased production of heat, for 
if evaporation from the wet skin was rapid the temperature rose, but 
if it was hindered by a covering of rubber the temperature fell. 

Bernard? found that very hot baths quickly caused death, the 
symptoms being similar to those observed from exposure to hot air. 

The influence of certain drugs upon the temperature of the 
body.— Alcohol.2—The effect of alcohol is a fall in temperature, and 
not, as is popularly believed, an increased heat of the body. It is 
true that after the use of alcohol there is a feeling of increased warmth, 
but this is due only to the increased vascularity of the skin and the 
activity of the sweat glands. 

Alcohol seems to act in two ways: it has little or no effect upon 
the production of heat in the tissues, but greatly increases the loss of 
heat by causing the cutaneous vessels to dilate, stimulating the sweat 
glands and quickening the circulation. The normal reaction to cold, 
namely, increased production of heat and contraction of the cutaneous 
vessels, is partly paralysed by large doses of alcohol, with the result that 
drunkards exposed to cold quickly “freeze” to death. 

Various observers * have found that alcohol taken in ordinary quan- 
tities as a beverage causes a slight depression, generally less than half 
a degree, in the temperature of healthy men; on the other hand, 
poisonous doses may cause a fall of five or six degrees—in fact, many 
of the lowest temperatures recorded in man have been observed in 
drunken persons exposed to cold. 

Experiments upon animals have given similar results. Walther ® 
exposed two rabbits to a temperature of 21°-2 below zero; in two and a 
quarter hours the temperature of the normal rabbit fell from 38°°8 to 
35°°6, while that of the rabbit which had received 35 c.c. of brandy fell 
from 38°8 to 19°8. A guinea-pig was given a dose of 6 or 7 grms. 
of brandy, and then exposed to moderate cold; its temperature fell 10°, 


1 Virchow’s Archiv, 1857, Bd. xi. S. 453. 

2 This article, p. 815. 

* For further details, see works on therapeutics. 

‘Davy, Phil. Trans., London, 1850, p. 444; Lichtenfels and Frohlich, Denkschriften 
d. k, Akad. d. Wissensch., Wien, 1852, Bd. iii. Abth. 2, S. 131; Lallemand, Perrin, and 
Duroy, ‘‘ Du réle de l’alcool et des anesthésiques dans l’organisme,” Paris, 1860; Ogle, 
St. George's Hosp. Rep., London, 1866, vol. i. p. 233. Ringer and Rickards, Lancet, 
London, 1866, vol. ii. p. 208; Cuny Bouvier, Arch. jf. d. ges. Physiol., Bonn, 1869, 
Bd. ii. 8S. 370 ; Godfrin, ‘De V’alcool, son action physiologique, ses applications théra- 
peutiques,” 1869; Weckerling, Deutsches Arch. f. klin. Med., Leipzig, 1877, Bd. xix. 
S. 317; Zuntz, Fortschr. d. Med., Berlin, 1887 ; Geppert, Arch. f. exper. Path. u. Phar- 
makol., Leipzig, Bd. xxii. Parkes and Wollowicz, Proc. Roy. Soc. London, 1870, vol. xvii. 
p. 362, found that alcohol in ordinary quantities had no effect on the temperature of a 
healthy man. 


° Arch. f. Anat., Physiol. w. wissensch. Med., Leipzig, 1865, S. 45. 


BODILY TEMPERATURE COMPATIBLE WITH LIFE. 821 


whereas that of a normal animal exposed to cold only varied one, or 
two-tenths of a degree. Similar results have been obtained by others. 

Calorimetric observations have been made by Reichert? upon the 
influence of alcohol on the production and loss of heat in dogs; he 
found that the total heat production was not essentially altered, but the 
loss exceeded the production, and therefore the temperature fell. The 
doses given were 1°25, 2°5, and 5 cc. per kilo. of the animal’s weight. 

Chloroform, ether, morphia, chloral, and nicotine—The general 
effect of these drugs is to cause a fall in the temperature of the body? 
and in poisonous doses to so greatly depress the power of heat regulation 
that a warm-blooded animal passes into a condition in which it cannot 
maintain its temperature, its respiratory exchange and temperature 
varying with, and in the same direction as, that of its surroundings 
(Rumpf, Pembrey). Calorimetrie observations made by J. Rosenthal 
show that under the influence of chloral the temperature of rabbits falls, 
the discharge of heat is 30 to 40 per cent. greater than the normal, and 
the production of heat and also of carbon dioxide is diminished ; strychnia 
and tetanus, on the other hand, increase the production but diminish the 
loss of heat. 

Cocain,° atropin, brucin, caffein, and veratrin raise the temperature ; 
the most remarkable pyretic drug, however, is 8-tetra hydronaphthyl- 
amine, which causes in the case of rabbits a rapid rise of three or four 
degrees in the rectal temperature®; curari? causes a marked fall in 
temperature. 

The limits of bodily temperature compatible with life.—Although 
the range of temperature in a normal man is less than 2’, yet a 
much wider range is observed in certain pathological conditions. 
Thus by exposure to cold, especially when the subjects are drunk, 
the temperature may fall even as low as 24° without a fatal issue. 
Reincke*® has recorded numerous cases of low temperature resulting 
from the accidental exposure of drunkards to cold air and water. 
In two of these cases the rectal temperature was 30° and 24° re- 
spectively: the patients were unconscious, but under treatment 


1Rumpf, Arch. f. d. ges. Physiol., Bonn, 1884, Bd. xxxiii. S. 538; Ringer and Rickards, 
loc. cit. ; Tscheschichin, Arch. f. Anat., Physiol. wu. wissensch. Med., 1866, S. 161; Cuny 
Bouvier, Zoc. cit. 

2 Therap. Gaz., Detroit, February, 1890. 

* Dumeril and Demarquay, ‘‘ Recherches expérimentales sur les modifications imprimées 
4 la temperature animale par l’ether et l’chloroforme,” 1848 ; Brown-Séquard, Compt. rend. 
Soc. de biol., Paris, 1849, No. 7, p. 102; Tscheschichin, Joc. cit. ; Lallemand, Perrin, and 
Duroy, ‘‘ Du réle de l’alcool et des anesthésiques dans Vorganisme,” Paris, 1860 ; Spencer 
Wells, Edin. Med. Journ., 1869, 1870; Richardson, Practitioner, London, 1869, 1870; 
Waren Tay, Brit. Med. Journ., London, 1870, vol. i. p. 329 ; Oglesby, Practitioner, London, 
1870; Angelesco, Compt. rend. Soc. de biol., Paris, 1894, p. 786 ; Richet, Compt. rend. Acad. 
d. sc., Paris, 1889, tome cix. p. 190; Arch. de physiol. norm. et path., Paris, 1890, tome ii. 
p- 221; Warter, Med. Times and Gaz., London, 1866, vol. ii. p. 416; Lichtenfels and 
Frohlich, Denkschriften d. k. Akad. d. Wissensch. Math.-naturw. Cl., Wien, 1852, Bd. iii. 
Abth. 2, S. 137; Hobday, Journ. Comp. Path. and Therap., Edin. and London, vol. viii. 
p- 287; Pembrey, ‘‘Proc. Physiol. Soc.,” Journ. Physiol., Cambridge and London, 1894— 
1895, vol. xvii. 

4 Sitzungsb. d. k. Akad. d. Wissensch. zw Berlin, 1890, Bd. xx. ; xxi. p. 393. 

5 Mantegazza, Ann. univ. di med. e chir., Milano, 1859, vol. clxvii. ; U. Mosso, Arch. 
ital. de biol., Turin, 1887, vol. viii. p. 370; 1891, vol. xiv. p. 288; Hobday, Journ. Comp. 
Path. and Therap., Edin. and London, 1895, vol. viii. p. 20; 1897, vol. x. p. 80. 

6 Stern, Virchow’s Archiv, 1889, Bd. exv. S. 14; Fawcett and Hale White, Journ. 
Physiol., Cambridge and London, 1897, vol. xxi. p. 435. 

7 This article, p. 841. 

8 Deutsches Arch. f. klin. Med., Leipzig, 1875, Bd. xvi. S. 12. 


822 ANIMAL HEAT. 


recovered in a day or two. In other cases, with temperatures 28°-4, 
27°, and 2674, death followed in about twenty-four hours. In a 
case observed by Nicolaysen! the rectal temperature was 24°7, but 
the drunkard, who had been exposed for a whole night to air 6° 
below zero, completely recovered; the temperature of the vagina and 
axilla was 27°9 in a woman who had had a similar experience, but 
within six hours the temperature rose to 36°35 under treatment, and the 
patient completely recovered.? In four cases of insanity, Lowenhardt * 
has observed temperatures as low as 25°, 29%5, 23°°75, and 28°; in one 
case the range of temperature for several weeks was from 25° to 35°. 
The patients were about 60 years of age; they often ran about naked 
in cold weather, and were frequently bathed on account of their dirty 
habits, and although they were fairly active they did not take much 
food. The observations were taken sometimes in the axilla, sometimes 
in the rectum. 

Weiland+ has recorded two cases of adults with temperatures 
reduced to 28°-4 and 26°°6 from exposure to cold; the observations were 
taken in the rectum several hours before death; in a third case, that of 
a drunkard who had been exposed to cold, the rectal temperature was 
30°:-4, and recovery took place. The rectal temperature of a man suffer- 
ing from bronchi-ectasis was found by Liebermeister° to be 32°6, and 
that of a child five days old, suffering from sclerema and icterus, 
32°15; the readings were taken a day or two before death, and several 
thermometers were used and tested. Kohler ® observed a temperature 
of 28°°2 in the rectum of a drunkard, and found that, notwithstanding 
treatment, it remained low until shortly before the man’s death a month 
later ; two cases, with rectal temperatures 26°°8 and 26°°7, were observed 
by Quincke ;* the subnormal temperature was due to exposure to cold, 
but both of the patients recovered. Numerous records of subnormal 
temperatures will be found in papers by Janssen,’ Lemcke,§ and Glaser. 

In the case of non-hibernating mammals an artificial cooling of the 
body to 18° is in a few hours followed by death, unless artificial respira- 
tion and heat be applied. Rabbits cooled to 18° are perfectly helpless 
and paralysed; the heart-beat is feeble, 16 to 20 per minute; the respira- 
tion is either exceedingly slow or rapid and shallow; the nerves and 
muscles long remain irritable, and during operative procedures there is 
very little bleeding, owing to the low blood pressure.'® 

It was shown by Edwards ! that newly-born pups and kittens would 
live for two or three days with their temperature reduced as low as 17° 
or 20°, and that the application of artificial warmth would restore the 
young animals, if this low temperature had not persisted too long. 
Adult animals, however, when cooled to 18° or 20°, generally died, even 

1 Jahresb. ii. d. Leistung. . . . d. ges. Med., Berlin, 1875, Bd. i. 8. 283. 

* Peter, Gaz. hebd. de méd., Paris, 1872, p. 499. 

* Allg. Zischr. f. Psychiat., etc., Berlin, 1868, Bd. xxv. S. 685. 

4 Schrift. d. Univ. zu Kiel, 1869, Bd. xvi. 

> ** Handbuch d. Path. u. Therap. des Fiebers,” 1875, S. 69. 

6 Schrift. d. Univ. zu Kiel, 1873, Bd. xx. 

7 Quoted from Janssen, Deutsches Arch. f. klin. Med., Leipzig, 1894, Bd. liii. S. 249. 

8 Tbid., 1883-84, Bd. xxxiy. S. 90. 
sae Fane Vorkommen und Ursachen abnorm niedriger Kirpertemperatur,” Diss., 

#O-e 

au Walther, Virehow’s Archiv, 1862, Bd. xxv. S. 414; dbid., 1865, S. 25 ; Horvath, 
Verhandl. d. phys.-med. Gesellsch. in Wiirzburg, 1881, Bd. xv. S. 187; Tscheschichin, 
Arch. f. Anat., Physiol. u. wissensch. Med. 1866, S. 151. 

1 «De influence des agens physiques sur la vie,” 1824, p. 237. 


BODILY TEMPERATURE COMPATIBLE WITH LIFE. 823 


when artificial warmth was applied. Similar results were obtained in 
the case of recently hatched and old birds. 

Hibernating mammals have been observed during winter with 
temperatures as low as 2°, and during summer they may be cooled by 
artificial means to 1°°2; in these cases the animals are able to again raise 
their temperature without any external aid (Walther, Horvath, and 
others). 

The eggs of silk-worms and of other insects may be exposed for a 
long time to temperatures 20° to 30° below zero, and yet will develop 
into larve when removed to warm surroundings! The Arctic ex- 
plorer Ross exposed caterpillars to a temperature of —42°, and found 
that they recovered when slowly thawed. Colasanti? observed that 
hens’ eggs could be exposed for two hours to a temperature of —4°, and 
for half an hour to a temperature of —7° to —10°, and yet developed 
normally when placed in an incubator. 

As already pointed ont on p. 817, in the lower vertebrates the tem- 
perature of the body may sink to zero and yet recovery take place. 
Hunter ? placed an eel in a freezing mixture, until the temperature of 
its stomach fell to —0°°6, when the animal appeared to be dead, but 
by the next day it had recovered; a similar result was observed in a 
frog. Frozen leeches, however, were dead when thawed. 

As regards the limit of high temperatures compatible with human 
life, there are numerous records of cases of hyperpyrexia. The highest 
observed by Wunderlich * was 44°°75 (112°55 F.) in a case of tetanus ; 
one hour after death the temperature was 45°37. Currie® found a 
temperature of 44°-45, Woodman ® one of 46:1 in fatal cases of scarlet 
fever; Baiumler’ records a case of sunstroke in a healthy man, the 
temperature in the axilla was 42°°9, there was deep coma, and death 
took place in eight hours; in a similar case observed by Casey ® the 
temperature in the axilla was 43°:1, and death occurred within three 
hours. Levick® gives cases of sunstroke in which the temperature was 
42°-8, and the patients recovered. Fatal cases with temperatures 43°, 
42°-5, and 44° are recorded by Simon,’ two cases of tetanus with 
temperatures 44°-4 and 41°°6 before death by Lehmann,!! and others 
with 43°-4, 43°-6, 42°°75, 43°-4, 43°-4, 44°3, and 43° by Quincke.” 

On the other hand, Donkin ® gives cases of temperatures as high as 
44°°2, 45°, and 44°°5, in which recovery took place; the high temperature, 
however, appears to have persisted for a very short time. In two cases 
of rheumatic hyperpyrexia recorded by Arkle “ the temperature was 
43°55 (110°4 F.), but the patients recovered. 


1 Réaumur, ‘‘ Mém. sur les insectes,” tomes ii. and v.; Spallanzani, ‘‘Opuse. de phys. 
anim.,” tome i. pp. 82-85; Bonafous, ‘‘ Biblioth. univ., Geneve, 1838, tome xvii. p. 200 ; 
Ross, ibid., 1836, tome iii. p. 423; Pictet, Arch. d. sc. phys. et nat., Geneve, 1893 (3), 
tome xxx. p. 293. 

2 Arch. f. Anat., Physiol. wu. wissensch. Med., 1875, 8. 477. 

ge Wiorks: * Palmer's edition, London, 1837, ‘vol. iv. p. 131 et seq. 

4 Medical Thermometry,” p. 204. 5 “* Medical Reports, etc.” 

® Med. Mirror, London, 1865, p. 77. 

7 Med. Times and Gaz., London, 1868, vol. ii. p. 118. 

8 Tbid., 1866, vol. ii. p. 26. 

9 Penn. Hosp. Rep., Philadelphia, 1868, vol. i. p. 369. 

0 (harité-Ann., Berlin, 1865, Bd. xiii. Heft 2, S. 1. 

1 Schmidt's Jaohrb., Leipzig, 1868, Bd. exxxix. S. 241. 

12 Berl. klin. Wehnschr., 1869, S. 301. 

13 Brit. Med. Journ., London, 1879, vol. ii. p. 983. 

4 Trans. Clin. Soc. London, 1888, vol. xxi. p. 187. 


824 ANIMAL HEAT. 


Richet! has collected three cases in which the temperature rose to 
46°, but the patients recovered. Numerous other cases of high 
temperature in man are to be found scattered throughout medical 
literature.? 

Experiments upon animals have determined more exactly the limit of 
high temperature. Bernard? found that when the internal temperature 
of rabbits was artificially raised to 45° they died; in birds the fatal 
limit was 51° or 52°. According to this physiologist, death was due to 
stoppage of the heart by the hot blood, which sent the muscle into rigor 
mortis. Rosenthal* obtained similar results for rabbits, but found that 
if the animal was removed to cooler surroundings when its temperature 
had reached 44°, recovery might take place. From these and similar ex- 
periments by Obernier,®? Wood,’ and others, it may be concluded that a 
bodily temperature of 45° is extremely dangerous, and one of 47° quickly 
fatal, to the life of mammals. The limit of high temperatures appears ° 
to be fixed by the point at which the proteids of the body begin to 
coagulate. 


THE TEMPERATURE OF DIFFERENT PARTS OF THE Bopy. 


The heat of the body is produced by processes of combustion taking 
place chiefly in the muscles and glands, while heat is lost chiefly from the 
surface of the skin. The result, therefore, is that the temperature of 
the body diminishes from the interior to the surface. It is impossible, 
however, to give any exact value to the temperature of different parts, 
because the production and loss of heat vary under different conditions 
of the animal, such as muscular activity and digestion. 

The temperature of internal parts in man.—In considering this 
subject, it is important to remember that the temperature taken by a 
thermometer placed ina dry, well-closed axilla represents the heat of 
an internal cavity; Ringer and Stuart’ even state that, “due care 
being taken and sufficient time allowed, the temperature of the axilla 
is always identical with that of the mouth, and with that of the rectum 
four to six inches above its termination.” 

Upon the respective temperatures of the mouth, axilla, and rectum, 
there is a great want of agreement among observers. This is in great 
part due to the fact that in numerous cases insufficient time is allowed 
for the determination of temperature in the mouth and axilla: but there 
is another cause, which is beyond the control of the observer—the 
circulation of blood in the mouth and in the skin of the axilla is liable 
to marked variations. It will be well, therefore, to mention the dis- 
cordant results obtained, and then draw some general conclusion. As 
just mentioned, Ringer and Stuart state that the temperature in the 
axilla is identical with that of the mouth and rectum; Ogle® says that 


1 Compt. rend. Soc. de biol., Paris, 1894, p. 416. 

* Hale White, Brit. Med. Journ., London, 1894, vol. ii. p. 1098. Here numerous 
references will be found. See also Trans. Clin. Soc. London, 1882, vol. xv. p. 261. 

3 Gaz. méd. de Paris, 1859, tome xiv. p. 462; ‘‘Lecons sur la chaleur animale,” 
p- 349. 

4“ Zur Kenntniss der Warmeregulirung bei den warmbliitigen Thieren,” Erlangen, 
STZ glo. 

> “ Der Hitzschlag,” Bonn, 1867, S. 71. 

6 « Fever,” Smithson. Contrib. Knowl., Washington, 1880, No. 357. 

7 Proc. Roy. Soc. London, 1877, vol. xxvi. p. 186. 

8 St. George’s Hosp. Rep., London, 1866, vol. i. p. 238. 


TEMPERATURE OF INTERNAL PARTS IN MAN. 825 


if the thermometer be warmed by the hand and then kept under the 
tongue in the closed mouth for eight minutes, the reading is the same 
as that obtained by inserting the thermometer in the urine as it leaves 
the body. On the other hand, Crombie! found, as the result of com- 
parative experiments in which care was taken to obtain accurate 
results, that in fifteen simultaneous observations the mean difference of 
temperature in the mouth was 0°15 above the reading in the axilla, and 
in thirty-five determinations the mean difference in the rectum was 
0-22 above the temperature in the mouth. A number of simultaneous 
observations made by Parkes and Wollowicz? show that the rectal 
temperature of a healthy man may be 05 to 06 higher than the 
temperature in the axilla. Gassot® made comparative observations at 
different times of the day, with the following results :— 


| MAN. Woman. 
| Time. — — 
Mouth. Axilla. | Mouth. | Axilla. Rectum. | 
i Yaa }, 37°06 37°°78 S70 ten See St. yk | Saad 
| | 
| Aji, | “Bxe76 Sime 37°°6 ay 38°-0 
Spats |e ovat: 2 pied ee NES 7 fas 37°°3 BATS: 
| 


Oertmann * observed, when the thermometer was kept in the axilla 
for fifteen minutes, in the rectum at a depth of 7 em. for five minutes, 
and in the stream of urie for five seconds, that the temperature of the 
urine was generally equal to that of the rectum, but four-tenths of a 
degree higher than that of the axilla. Ten simultaneous observations 
of the temperature in the mouth and rectum gave an average difference 
of 0°32 in favour of the latter (Cuny Bouvier) According to Lieber- 
meister,® the rectal temperature is 0°-1 to 0°-4 above that of the axilla. 

Lorain’ maintained that the temperature in the rectum or vagina 
alone represented the internal temperature of the body, and that the 
rectal temperature was ‘6° to ‘8° higher than that in the axilla. The 
figures given by Wunderlich § for the mean temperature of the rectum, 
mouth, and axilla are 37°3, 37°15, and 57° respectively. Redard,® on 
the other hand, states that the temperature of the mouth is ‘2° higher 
than that in the axilla, and °3° to ‘6° lower than that of the rectum. 
Neuhauss?° found, as the result of forty comparative experiments, in 
which the temperature was observed simultaneously in the rectum 
and in the axilla, that the rectal was 0°6 higher than the axillary 
temperature. 

We may take as our guide the averages obtained from the results 
of different observers, and conclude that the rectum has a temperature 

1 Indian Ann. Med. Sc., Calcutta, 1873, vol. xvi. p. 558. 

2 Proc. Roy. Soc. London, 1869-70, vol. xviii. p. 368. 

3 These de Paris, 1873, quoted from Richet, Rev. scient., Paris, 1885, tome ix. p. 433. 
* Arch. f. d. ges. Physiol., Bonn, 1878, Bd. xvi. S. 101. . 

5 Ibid., 1869, Bd. ii. S. 387. 

6 ** Handbuch d. Path. u. Therap. des Fiebers,” S. 44. 

7 ** Te Ja temperature du corps humain,” Paris, 1877, tome i. p. 434. 

8 “* Medical Thermometry.” 


9 «« Etudes de thermometrie clinique,” 1874, p. 20. 
0 Virchows Archiv, 1893, Bd. exxxiv. S. 365. 


$26 ANIMAL HEAT. 
0°-4 above that of the mouth, and that the difference between the 
temperature of the axilla and of the mouth is so small that it may be 
neglected, especially since the variation is not constantly in favour of 
the one or the other. 

The temperature of internal parts in animals.— Numerous 
observations have been made upon the temperature of the internal 
parts of animals, either during life or immediately after death. Some 


of these results are now given in the following tables : — 


Animal. Temperature of Part. Observer. 
| | 
(| Rectum, 38° | Hunter. 
| | Right ventricle, 38°°3 
Jk) | = > 99 
Dog all Liver, 38°°2 p 
Stomach, 38°°3 5 
be f| Aorta, 38°°6 Bernard. 
| aes * \| Portal vein, 38°°8 B 
‘| Rectum, 40°°8 Davy.? 
| Liver, 41°°4 a 
Lung, 41°'4 i 
ne + | Right ventricle, 41°°1 $5 
JES | | Left ventricle, 41°°7 3 
Blood of jugular vein, 40°'8 45 
| (| Blood of carotid artery, 41°-7 _ 
| Dogs | Blood in abdominal aorta, 38°°3-38°°6 Bayliss and Hill.4 
| Rectum, 40°, 40°°6, 40°°6, 40°6 Davy.? 
TaABS | Right ventricle, 40°°8, 40°°6, 40°°S, | as 
: \ | Al**] 
> J - es = OM 
uate || Left ventricle, 41°", 41°-1, 41°-4, 41°°7 7 
jus i Blood of jugular vein, 40° is 
_| Blood of carotid artery, 40°°8 te 
Bae f| Portal vein, 40°°2 Bernard.°® 
hes te * \| Hepatic vein, 40°°6 | 5 
| as) || Brain, 40°, 41°, 40°8 | Davy.® | 
He dea Rectum, 40°°4, 40°°S, 41°4 | $ 
| : \ | 
ms (| Cloaca, 42°:2 Davy.® 
Turkey, j Gizzard, 42°°8 
just dead } LS 3 ” 
: L Pectoral muscle, 42°°2 ie 


| | | | 


Hobday? finds in the case of horses, cows, sheep, dogs, and pigs, that 
the vaginal temperature is generally one-tenth of a degree lower than 
that of the rectum; at the times of cestrum, however, the vagina often 
has the higher temperature. 

The temperature of arterial and venous blood.—The temperature 
of the blood has attracted considerable attention for many years— 
first, on account of the ancient view that the heat of the body was 
produced in the heart: and, secondly, because the work of Lavoisier 
and Crawford tended to show that heat was produced in the blood 
as it passed through the lungs or other parts of the body. More re- 
cently, attention has again been directed to this question by Berthelot,’ 
who shows that a certain amount of heat is formed in the lungs by 


1 The results of other observations will be found in Rosenthal’s article, Hermann’s 
‘* Handbuch,” Bd. iv. Th. 2, S. 398. 

2 “Works,” Palmer's edition, London, 1837, vol. iv. p. 145. 

3 * Researches,” London, 1839, vol. i. p. 147; Phil. Trans., London, 1814, p. 590. 

4 Journ. Physiol., Cambridge and London, 1894, vol. xvi. p. 351. 

° **Lecons sur la chaleur animale,” 1876, p. 188. 
6 «* Researches,” London, 1839, vol. i. p. 159. 


Vet. Record, London, 1896, vol. viii. p. 488. 8 This article, p. 839. 


TEMPERATURE OF ARTERIAL AND VENOUS BLOOD. 827 


the combination of oxygen with hemoglobin. The numerous results 
obtained by different observers have been collected by Bernard,’ and 
are given in the following tables :— 


TABLE I. 
Results in which the Arterial Blood is warmer than the Venous. 


| Arterial Venous | Differ- | 


Nasse‘ (1843) | 41°- 
ventricle ; great dead, chest | 


Author. | ilaeae jl aNinesk. || Gare | Animal. Part Examined. Method. 

+ aaa ea 

Haller? (1760), | 37°:2 36°°1 bis | 2 2 | 2 

Schwenke | 
Crawford? (1778) | 38°-8 | 37°°-5 | 1°°3 | Sheep. | Carotid artery, jug-| Thermometer | 
| ular vein. | placed in|} 
blood col- | 
| lected. 
Krimer (1823) | 38°-18 | 37°:20 | 0°-98 |Man. | Temporal artery, | Thermometer 
jugular vein. ies} esti OW 
blood. 
37°°5 | 86°°6 0°-9 | Woman. | os 5 
| 37°°2 | 36°-3 0°-9 |» Man. Amputation ofarm, Ss 
brachial artery 
| and vein. 
Scudamore? | 37°-7_ | 36°-6 1°-1 | Sheep. | Carotid artery, jug- 5 
(1826) | | | ular vein. 
|36°1 | 35°5 | 06 | Man. | Temporal artery, | e 
vein of arm. 
Saissy ° (1808) | 38°-5 | 38°-0 | 0°°5 | Marmot.) Right and left|Incision of 
| ventricle. | heart. 
/ 36°°5 36°°0 0°°5 | Hedge- 33 ” 
| hog. 
i ae CO ES sie 0°°5 =| Squirrel. sa Experiments 
on two ani- 
| mals com- 
| pared. 
: Siiecde oe) 0°-4 | Bat. » >» 

J. Davy ® (1815) | 40°-0 | 39°-1 0°-9 Lamb. | Carotid artery, jug-| One thermo- 
| ular vein. | meterinvein, 
| anotherinjet 
of arterial 

blood. 
40°53 | 40°-0 | 0° Es = 3 
| 40°°5 | 40°°0 0°°5 |} ” o oe 
| | 40°°5 397 0° 8 | 3 oe) a) 
| | 40°°5 | 40°-0 0° 5 } 33 > | 0 } 
4072397 | 075.) Rives =p : ” 
| 40°:0 39°°1 0° 9 33 | 3 23 
1402-08 pra9r=4" | 0°-6) |) Ss | 2» ) 
138°°6 | Saal Ord Ox | ” » 
(SSucemlacersy ll) Or :O vein * 
1 | 40°°8 0°°3. + | Lamb. | Right and left Animals just | 
| 
| 


intestine, 40°°0| opened, ven- | 
41°-1 | 40 °5 0°°6 - 40°°5| tricles in- | 
41°°] AQ=8 1) OFS oe 40°°5 cised. 
42°°8 | 41°-25 | 1°55 |? s e | 
sacs. |-40%6 | 1°27 eae 4 = 
1°:25 2 | 


| 42°°5 | 41°25 | 


| 29 | 29 


[Continued on next page. 


1 «*Tecons sur la chaleur animale,” 1876, p. 40 ef seq. 

2 *¢Elementa Physiol.,” 1760. 

3 «Experiments and Observations on Animal Heat,” London, 1779. 
‘* An Essay on the Blood,” London, 1824. 

“*Recherches expérimentales,” etc., Paris, 1808, p. 69. 

© Phil. Trans., London, 1814. 

7 Rheinisch. u. Westphal. Correspondenzbl., 1843, 1844, 1845. 


ib 


or 


828 


ANIMAL HEAT. 


| Arterial 


‘Venous 


Differ- | 


TABLE I.—continued. 


Author, Blood. | Blood. | ence. | Animal. | Part Examined. | Method. 
Becquerel and | 0°84 | Dog. Aorta where it left | Thermo - elec- 
Breschet! | | heart; inferior tric needles, 
(1839) | | vena cava where! chest opened 
| | it entered heart.| in animals 
| | just dead. 
artigo Wee We | Crural artery and | er 
| vein. | 
0°°84 3 | ” ” 
One4elh ee | Carotid artery, cru- 55 
ral vein. 
| 38°-90.] 88°°0 | 0°90] ,, _ Crural artery and “f 
| | | jugular vein. 
TaBLe II. 


Results in which the Venous Blood is warmer than the Arterial. 


Author. | cee yes | pe Animal. Part Examined. 
|_ } 
Berger ? (1833) bata 41°40 | 0°:50 | Sheep. Right and left 
ventricle. 
Collard de Mar- iL (0). || 1D Yoyex 3 
tigny,® and | 
Malgaigne | 
(1832) | 
Magendie and | Horse. | Right ventricle 
Claude Ber- | | warmer than 
nard (1844) left. 
Claude Bernard | Dog. | Inferior venacava 
(1849) | at level of liver | 
‘ warmer than 
aorta. 
Hering * (1850) | 38°°77 | 39°°30 | 0°53 | Calf with | Right and left | 
ectopia| ventricle. 
of heart. | 
G. Liebig5 (1854) | 36°32 | 36°35 | 0°73 | Dog. | _ 
| 
Claude Bernard | 38°:0 | 38°:2 0°:2 | Dog Pr 
(1857) 39°3 |39°5 | 0-2 | ,. 
30° | 39°" "| O° a . 
BO°s6isB°SB"? || on eae * 
38°-5.AliS8°7 1] MOnDuM mes 4 
88°69 || 3878 | | ocamaLt | é 
Sot oer! || Oral ‘ | - 
Bere mages! | (oan | s 
33-8). (882-9 4!) 0°Timlel. ¢ | 
39°-2 | 39°4 | 07-2 | |, | d | 
40°12 | 40°37 | 0°25 |Sheep. | i 
39°-92 | 40°32 | 0°40] ,, 6 
| 39°58 | 39°60 | 07-02] | | ip 
40°-24 | 40°39 | 0°15 |, = 
39°58 | 39°87 | 0-29 | 7 | « 
40°-09 | 40°48 | 0°39 | ,, | 2 


Method. 


Not stated. 


Animal just 
dead ; chest 
partly open. 


Animal alive ; 
circulation 
not inter- 
rupted. 

Animal alive ; 
thermometer 
introduced by 
the abdomen. 

Incision of ven- 
tricles. 


Animal alive ; 
circulation 
not inter- 
rupted ; ther- 
mometers in- 
troduced by 
vessels of neck 


99 
39 
29 
7 
39 
29 
9? 
9 
29 


3? 


1 Ann. d. sc. nat., Paris, ‘‘ Zool.,” Sér. 2, tomes iii. and iv. 
* Mém. Soc. de phys. et Uhist. nat. de Genéve, 1833, tome vi. p. 353. 
3 Journ. compl. d. sc. méd., Paris, 1832, tome xliii. p. 386. 
4 Arch. f. physiol. Heilk., Stuttgart, 1850. 
° “* Ueber die Temperaturunterschiede des venosen und arteriellen Blutes,” Giessen, 1853. 


TEMPERATURE OF THE SKIN. 829 


It will be seen from the two tables that the results lead to directly 
opposed conclusions, but a critical examination shows that the correct 
one is probably that the blood in the right ventricle is 0°1 to 0°:2 
warmer than that in the left. In many of the older experiments the 
methods were inexact, the chest was opened and the heart exposed; 
the right ventricle, on account of its thin walls, would cool more quickly 
than the left, as shown experimentally by G. Liebig. The most exact 
method appears to be the insertion of delicate thermometers or thermo- 
electric needles down the jugular vein and the carotid artery into the 
right and left ventricle respectively. This method was employed by 
Heidenhain and Korner! in numerous experiments upon dogs, with the 
result that in all but one of the observations the right side of the heart 
was warmer than the left. Thus in one case the difference was ‘6°, 
in two ‘5° to ‘6°, in three ‘5°, in five *5° to ‘4°, in twenty-seven °2° to ‘3°, 
in thirty-six ‘1° to ‘2°,in twenty-one ‘15°, in one case no difference at 
all. To determine whether the inspiration of cold air was the cause of 
this difference, Heidenhain and Korner made comparative experiments, 
employing for artificial respiration in the one case cold air (17°), and in 
the other hot air (40°) saturated with moisture. The difference still 
remained, and it was therefore concluded that respiration was not the 
cause; cold air when inspired is warmed and saturated with moisture 
before it reaches the alveoli ;? further, in passing through the upper 
parts of the respiratory tract, the cold air would cool the blood in veins 
going to the superior vena cava and thus to the right side of the heart. 
These observers conclude that in the dog the right ventricle is warmer 
than the left, because its walls lhe nearer to the liver and other 
abdominal organs, which have a high temperature, while the left 
ventricle is surrounded by lung. It was found, in fact, that the 
difference in temperature could be reduced to a minus quantity by 
artificially lowering the temperature of the abdominal cavity. Bernard 
does not accept this explanation as satisfactory; for he points out that 
in Hering’s observation the right ventricle was half a degree warmer 
than the left, although the heart, owing to a congenital defect, was 
outside the thorax. 

The temperature of the skin.—The temperature of the human skin 
shows differences in different parts of the body, and is also subject to 
variations due to alterations in the external temperature, the amount of 
natural or artificial covering, the vascularity of the parts, and the 
amount of evaporation taking place from the surface. Apart from 
these variations, there is a difficulty in measuring accurately the 
temperature of the skin; a mercurial thermometer applied to the skin 
recelves heat from the surface in contact with the skin, and loses 
heat from the surface exposed to the air. If, on the other hand, 
the thermometer is covered with a non-conductor, or the external 
temperature is raised, then the heat of the part of the skin observed 
is increased. To overcome these difficulties, thermo-electric methods 
have’ been used.? 

The disadvantages of these thermo-electric methods are the complexity 

1 Arch. f. d. ges. Physiol., Bonn, 1871, Bd. iv. S. 558. 

2 See ‘‘ Chemistry of Respiration,” this Text-book, vol. i. p. 754. 

’ Christiani and Kronecker, Arch. f. Physiol., Leipzig, 1878, S. 334; Kunkel, Ztschr. f. 
Biol., Miinchen, 1889, Bd. xxv. S. 55; Masje, Virchow’s Archiv, Bd. evii. S. 17, 267 ; 


Geigel, Verhandl. d. phys.-med. Gesellsch. in Wiirzburg, 1888, N. F., Bd. xxii. S. 8; 
Stewart, Stud. Physiol. Lab. Owens Coll., Manchester, 1891, vol. i. p. 100. 


830 ANIMAL HEAT. 


of the apparatus required, the necessity of graduation, and the time 
taken in observation. Bayliss and Hill! found that the wire-resistance 
thermometer? could not be employed for the investigation of changes 
of temperature in a warm-blooded animal: the slightest movements, as 
those of artificial respiration, in the curarised animal producing deflec- 
tions of the galvanometer. A flat mercurial thermometer, on the other 
hand, is easily applied, and furnishes comparative data of considerable 
values 

Some of the earliest experiments with mercurial thermometers were 
made by J. Davy, who obtained the following results, when the 
temperature of the room was 21° :— 


Sole of the foot . : 32°°2 | Middle of the rectus femoris 32°°78 
Between internal See: Groin ‘ . obra 

and tendo Achillis . . 33°°89 One inch below aon =, poo 70e 
Middle of tibia . . . 33°°06 | Left sixth rib over heart . 34°-44 
Middle of calf. : . 33°89 | Right sixth rib . : issn 
Bend of the knee saad, 00 Axilla (closed). : -; (pee 
Middle of the thigh. . 34°44 | 


Kunkel used a thermo-electric method, which was exact to about 
0°-1, and obtained the following results for the temperature of different 
parts of the skin of a healthy muscular man, 35 years of age, 179 em. 
in height, and 84 kilos. in weight. The temperature of the room 
was 20°: 


Forehead 34°1-34°°4 | Arm . ; ; hs . -34°3 
Over malar bone ‘ 34°°1  Sternum . : . 34°4 
Cheek under malar bone 34°-4 Over pectoralis major : 7 TT 
Lobe of ear : : 28°°8 | Over heart . : : . 34°°6 
Back of hand ‘ _ 32°-5-33°-2 | Right iliac fossa . ‘ . 3844 
Palm of hand (closed for some | Left - P . 34°6 
time) . 34°°8-35°:1 | Back, over sacrum 2 «ion 3 
Palm of hand (open) . 34°-4-34°°8 |  ,, overribs . ai oh 

Wrist . : ; ; (33 1. | Buttock ; i . 82°-05 
Forearm F ; : - oo has 2 highic. ? : ; >) ae 
»> Upper part : ok Dal Callens ; : ‘ goo 


Experiments were also made upon the effect of exposure to cold. 
Thus, after the man hghtly clothed had taken a walk for half an hour 
in a cold, sharp, north-east wind (—5°), the following temperatures were 
observed—tace, 27°°7-28°°7 ; back of hand, 24°°7; chest and abdomen, 
32°1; arm, 30°°7-31°:1; but after he had remained for forty minutes in 
a room at 15°, the face had a temperature of 34°-6, the back of the hand 
31°-2, and the abdomen 35° 

Working the muscles of one arm raised the temperature of the skin 


1 Journ. Physiol., Cambridge and London, 1894, vol. xvi. p. 352. 

2 Rolleston, zbid., 1890, vol. xi. p. 208. 

3 Davy, Phil. Trans., London, 1814, vol. civ. p. 590; ‘‘ Researches,’’ London, 1839, 
vol. i. p. 150; Alvarenga, “ Précis de thermométrie clinique générale,” 1871, p. 45; 
Waller, “Proc. Physiol. Soc.,” Journ. Physiol., Cambridge and London, 1894, vol. xv. ; 
Hale White, Croonian Lectures, Lancet, London, June 19th, 1897, Brit. Med. Journ., 
London, 1897, vol. i. p. 1654; Pembrey, ‘‘ Proc. Physiol. Soc.,”” Journ. Physiol., Cam- 
bridge and London, 1897, vol. xxi. 

£°7Ztschr. FF Biol., Miinchen, 1889, Bd. xxv. S. 55. 

> This low reading Kunkel attributes to the loss of heat by conduction when the man 
was sitting down. 


REGULATION OF TEMPERATURE. 831 


of that part above 54°, whereas the temperature of the abdomen was 
only 52°°5. The highest temperature observed in healthy men was 
35°°6, on the skin of the face. 

Kunkel concludes from his observations that the temperature of the 
human skin is almost constant, and that the temperature of the body is 
regulated to a very slight degree by changes in the temperature of the 
skin. 


THE REGULATION OF TEMPERATURE. 


Inasmuch as the constancy of temperature varies in different 
animals, and even in the same animal under different conditions, such 
as age and hibernation, so also various grades of perfection are observed 
in the power of regulation. In man this power is so greatly developed 
that his temperature is almost the same, whether he lives in the Arctic. 
regions, with an external temperature 50° below zero, or in the Tropics, 
where the temperature of the air may be as high as 48°. For shorter 
periods a man can remain in a room heated to 121° without the 
temperature of his body rising above the normal! Other mammals 
have a less perfect regulation, as shown by the greater variations of 
their temperature. 

In young immature mammals and birds the power of regulation 
is imperfect, for when they are exposed to cold their temperature falls, 
and they pass into a condition in which they resemble the cold-blooded 
animals, their temperature rising and falling with that of their sur- 
roundings. A similar imperfection in regulation is seen in some 
mammals during hibernation. Lastly, in the so-called cold-blooded 
animals, there are various grades in this capacity for regulating tempera- 
ture, as is shown by the high temperature of bees in winter, when com- 
pared with that of most of the lower animals, in which there is a mere 
trace of regulation. 

Even in those warm-blooded animals which possess a perfect power 
of heat regulation, there are limits to this power. If the animal be 
exposed to excessive cold, the loss of heat is great, and only within 
certain limits can compensation be effected by an increased produc- 
tion of heat. When compensation fails, then the animal’s temperature 
falls, its bodily and mental activities are diminished, and it passes into 
a sleepy, unconscious condition which ends in death. Such a condition 
is observed in men or animals before they are “frozen to death.” 

On the other hand, extreme heat can only be resisted within a 
certain range; the production of heat in the body can be diminished, 
but not suspended ; the loss of heat can be greatly increased by sweating 
and by a greater exposure of blood in the vessels of the skin, but if the 
air be of a temperature equal to, or nearly equal to, that of the body, 
and greatly laden with moisture, then the loss of heat is slight or even 
suspended. Under such circumstances the internal temperature of the 

animal rises rapidly to a point incompatible with life. The extremes 
of heat and cold which can be borne without injury to life, have already 
been discussed. f 

The mean temperature of the higher animals is fairly constant 
under very great differences of external temperature, and to maintain 
such a condition the loss and the production of heat must be almost equal. 
That there is no perfect equality has already been shown in the daily 


1 Bladgen, Phil. Trans., London, 1775, vol. lxv. p. 484. This article, p. 814. 


832 ANIMAL HEAT: 


variation of the temperature of the body, in the rise of temperature 
observed after exercise, and during residence in tropical climates. 

The regulation of temperature, therefore, embraces two processes— 
regulation by varying loss of heat, regulation by varying production of 
heat. 

The regulation of heat production.—In considering the regulation 
of heat production, it is necessary to trace out briefly the various 
discoveries which have established, as a fact, that animal heat is due 
to combustion within the tissues. 


Historical account of facts and theories upon the sources of 
animal heat.!—The ancients considered animal heat to be beyond the reach 
of physical and chemical laws. They could assign no cause for it, and there- 
fore looked upon it as some innate quality, something essentially “vital.” 
This “vital” heat was supposed to be concentrated in the heart (Plato, Aris- 
totle, Galen), and to be distributed to the body by the blood in the veins. It 
was prevented from accumulating by respiration, the chief function of which 
was to cool and temper the blood. 

As knowledge in physical and chemical processes increased, attempts were 
made to give a rational explanation of animal heat. It was well known that 
heat arose during fermentation, and by the contact of acid and base ; animal 
heat was therefore considered to arise by some similar process or processes 
taking place in the blood. Willis,? about the year 1670, put forward the 
theory that there is in the blood a combustion which depends upon the fer- 
mentation excited by the combination of different chemical substances.  Fric- 
tion was another well-known source of heat, and was the explanation given by 
Boerhaave ;? he considered that animal heat was due to the friction of the 
blood corpuscles in the vessels. Stephen Hales* adopted this theory, and gave 
certain experiments, which he thought supported it. 

A much more correct opinion had already been formed in 1674 by Mayow,? 
who, after his experiments on the constitution of air and its relation to the 
heat of combustion, extended the analogy of combustion to animal heat. He 
held that the function of the lungs was not to cool the blood, but to enable 
that fluid to absorb the nitro-aerial gas (oxygen) of the air, and so generate 
heat. 

Later research has shown that the heat of living things is not due to any 
mystical so-called “vital” force, but to the processes of combustion, which 
form one of the most important phenomena of life. The different steps by 
which this knowledge has been attained are found in the discovery of Black,® 
that carbon dioxide was produced in animals by a process of combustion ; in 
the work of Lavoisier? and Crawford,’ who showed that the heat of an animal 
might be accounted for by the processes of combustion ; in the researches of 
Dulong® and Despretz,!° whose results, when critically examined and explained 
by Liebig,!! formed an important support for the law of the conservation of 
energy. 

1 Accounts of the old theories will be found in C. Bostock, ‘‘ Essay on Respiration” ; 
‘‘An Elementary System of Physiology,” 2nd edition, 1828, vol. ii. p. 243; Gavarret, 
‘De la chaleur produite par les étres vivants,” Paris, 1855; and ‘‘ Les phenoménes phy- 
siques de la vie,” Paris, 1869; Lorain, ‘‘De la temperature du corps humain,”’ Paris, 
1877, vol. i. p. 39; Rubner, Zéschr. f. Biol., Miinchen, 1893-94, Bd. xxx. 8. 73. 

» «De Accensione Sanguinis.” 5“ Aphor. cum Notis Sweiten,” pp. 382, 675. 

4“ Statical Essays,” 2nd edition, 1733, vol. i. p. 90. 

> «¢Tractatus Quinque,” Oxon, 1674. 

6 «Lectures on Chemistry,” edited by Robison, Edinburgh, 1803. 

7 Hist. Acad. roy. d. sc., Paris, 1777. 

8 **De calore Animali,” 1779; ‘‘ Experiments and Observations on Animal Heat,” 


1788. 
9 Ann. de chim. et phys., Paris, 1843, Ser. 3, tome i. p. 440. 
0 [bid., 1824, Sér. 2, tome xxvi. p. 337. 11 ««Thierchemie,’’ S. 28. 


CHEMICAL CHANGE AND HEAT PRODUCTION. 833 


Helmholtz, Ludwig, Pfliiger, and others, by their investigations upon the 
production of heat in muscle, glands, and other tissues, and their determina- 
tions of the respiratory exchange of animals, have indicated where and how 
heat is produced. Finally, the exact determinations made by Rubner! upon 
heat production and metabolism have proved that chemical change is the 
cause of animal heat. Simultaneous determinations of the exchange of 
material and the production of heat in dogs, under different conditions as 
regards diet, were made, and the results show that the heat of combustion of 
the food, as determined in a calorimeter, is equal to the heat given off by the 
animal; in fact, the animal must be looked upon as a living calorimeter, in 
which the food is burnt. The results are so exact that they prove the con- 
servation of energy in a vital process. 


Condition of the Animal. Heat as Calculated. iF CHIbHeee Pees 
Fasting : > ‘ 1296°3 cal. 1305°2 +0°69 
| Diet of fat | 15101 ,, 14953 | 2-097) 
Diet of flesh and fat | 2492°4 ,, 2488°0 -—0°17 
Diet of flesh Salt Kil | 4780°8 ,, 4769°3 ~ 0°24 


The above figures only give some of the results, but the mean of all the 
experiments shows that the amount of heat, as determined directly by the 
animal calorimeter, is only 0°47 per cent. less than the amount as calculated 
from the heats of combustion of the different substances which have been 
decomposed in the animal’s body. 


THE RELATION OF CHEMICAL CHANGE TO HEAT PRODUCTION. 


A consideration of the law of the conservation of energy leads to the 
conclusion that the sole cause of animal heat is a chemical process, a 
combustion of food substances by the oxygen taken in by the animal ; 
as just mentioned, the experimental proof of this conclusion has been 
recently given by Rubner. The chemical energy of the ingesta 
manifests itself chiefly in two forms, heat and motion. 

In this connection it is important to consider the heats of combus- 
tion of the various substances which form part of an animal’s body or 
food, for it will thereby be possible to determine indirectly the amount 
of heat produced by an animal. A given amount of chemical action is 
accompanied by the production or the absorption of a definite quantity 
of heat. The accurate determination of this quantitative relation is 
beset with considerable difficulties, for the chemical changes in the 
complex substances of animal tissues or food are rarely simple, and are 
accompanied by physical changes, which have to be measured and taken 
into account before the amount of heat due to the chemical change can 
be estimated. Chemical decomposition is attended with the absorption 
of a quantity of heat equal to that which would be evolved by the 
combination of the same chemical substances.2 Therefore, in the 


1 Zischr. f. Biol., Miinchen, 1894, Bd. xxx. S. 135. 

2 Favre and Silbermann, Ann. de chim. et phys., Paris, 1842, Sér. 3, tome xxxiy. 
p. 357 ; Woods, London, Edinburgh, and Dublin Phil. Mag., London, 1851, vol. ii. p. 268, 
1852, vol. iv. p. 370; Joule, zbid., 1852, vol. iii. p. 481. 


VOL. I.—53 


834 ANIMAL HEAT. 


estimation of the production of heat during a complex chemical change, 
involving combination and decomposition, it is only necessary to 
consider the first and final conditions of the substances, whatever may 
have been the intermediate stages.? 

The determination of the heat produced or absorbed by chemical 
change is made by enclosing the acting substances in a chamber sur- 
rounded by water or mercury, the rise or fall of temperature in which 
indicates the amount of heat produced or absorbed, as the case may 
be.” 

The. heat of combustion of substances of physiological interest has 
been determined by various observers;* the following table gives the 
values of some of the most important substances :— 


| \| | 1 
2 pe Subste 3 , 
gr (ary). | Combustion, | Authority. || ‘rm (dry), | Combustion, | Authority. 
| | | 
Hydrogen. | 33,881 cal.4; Andrews. | Casein. . .| 5,855cal. | Danilewsky. 
- : | 34,662 ,, | Favreand Sil-|) ,, . . .| 5,867 ,, /| Stelmann. 
| bermann. |, dhasis ahs Heel 301) ONSA Oe ‘6 
Carbon . .| 7,900 ,, | Andrews. | Cows’ milk .| 5,733 ,, | Danilewsky. 
>,  Wood- \g 080 f| Favre and Sil- || Women’smilk| 4,837 ,, 
charcoal .|f~~~ » \|  bermann. | Hat =| S, | Os68Gny ms 
Cheese. . .| 6,114 ,, | Frankland. Wes « . «| 9)423)5,— | Ruler 
Rotaboes) 2 11) 935752), i || Dextrose . .| 38,939 ,, | Rechenberg.® 
4 en | e284 eee Damilewskevee Maltose . .| 4,163 ,, as 
Lean beef. .| 5,313 ,, | Frankland. || Milk sugar .| 4,162 ,, a 
i. oe (7B ,, |Danilewsky. || Starch. . .| 4,479 ,, 3 
* - «| -5,641.,,. | Stohmann.®)) |! 4, _. .. |) 4,82 SiS toh 
if 54) SHG: a5) alone Cane-sugar .| 4,176 ,, | Danilewsky. 
White ofege | 4,896 ,, | Frankland. || Glycogen. .| 4,190 ,, | Stohmann. 
Yolk of egg .| 6,460 ,, | 55 || Cellulose . .| 4,185 ,, a 
Butter (oop a eal i |Urea . . .| 2,537 ,, | Damilewsky. 
Bread crumb. | 3,984 ,, ce gy SS P9587) a Site neta 
Blood fibrin .| 5,772 ,, | Danilewsky. yy ew | 255252 Benthelo imac 
Py .| 5,637 ,, | Stohmann.? | Petit.1° 
Peptone . .| 4,876 ,, | Danilewsky. 35) allie ol] 62, 523%, an mang barened 
ie ripe (ps 208 eae bola: || Uric acid. .| 2,741 ,, | Stohmann. 
Serumalbumin} 5,917 ,, A Hippuric acid | 5,678 ,, . 
Hemoglobin. | 5,885 ,, | as || Feces. . .| 4,479 ,, | Rechenberg. 


The above table shows that the different foodstuffs have different 
values as producers of heat, and from these it is possible to calculate 
the physical value of one kind of food in terms of the others. The 


1 Hess, quoted from Rubner (Ztschr. 7. Biol., Miinchen, 1894, Bd. xxx. 8. 135). 

2 For further details on such calorimeters, see Miller, ‘‘ Chemical Physics,” p. 338, and 
Watts’ ‘‘ Dictionary of Chemistry,” vol. ili. pp. 28, 103; Stohmann, Journ. f. prakt. 
Chem., Leipzig (2), Bd. xix. 8. 115; Bd. xxxix. 8. 503. 

3 Crawford, ‘‘On Animal Heat,” 1788, 2nd edition, pp. 320, 333, 351; Favre and 
Silbermann, Ann. de chim. et phys., Paris, 1842, tome xxxiv. p. 357; Frankland, London, 
Edinburgh, and Dublin Phil. Mag., London, 1866, vol. xxxil. p. 182; Hermann, Ber. d. 
deutsch. chem. Geselisch., Berlin, 1868, 8. 18, 84; Rubner, Ztschr. f. Biol., Miinchen, 1885, 
Bd. xxi. S. 357; Berthelot, Compt. rend. Acad. d. sc., Paris, 1886, tome cii. pp. 1211, 
1284, 

4 Calorie=the heat required to raise 1 grm. of water 1° C. ; kilo-ealorie=1000 calories= 
heat required to raise 1 kilo of water 1° C. 

5 Arch. f. d. ges. Physiol., Bonn, 1885, Bd. xxxvi. S. 230. 

8 Journ. f. prakt. Chem., Leipzig, Bd. xliv. 8. 336. 

7 Ztschr. f. Biol., Miinchen, 1893-94, Bd. xxx. S. 88. 

8 Tbid., 1895, Bd. xxxi. S. 364. 

® “Ueber die Verbrennungswarme organischer Substanzen,” Leipzig, 1880. 

0 Compt. rend. Acad. d. sc., Paris, 1889, tome cix. p. 759. 


CHEMICAL CHANGE AND HEAT PRODUCTION. 835 


following table of isodynamie foodstuffs is taken from Danilewsky’s 
work :— 


Fat. Starch. ured | Saute) Cellulose. | Peptone. et of 
| 

100 grms. | 
casein =| 61 133 151 | 142 133 | 121 135 

100 grms. 
fat = 100 220 250 236 221 (ee 2 OL 224 

100 grms. 
Starch | = 46 100 114 107 100 | 92 102 

| 


The above data are for physical values. It is necessary, therefore, 
to determine how far the different foodstuffs undergo combustion in 
the living body, and what values they have as producers of heat during 
that combustion. 

Rubner has shown that some of the products of the combustion of 
proteid escape in the feces as well as in the urine; the heat value of 
these substances must be determined and deducted from the heat of 
combustion of proteid. The reduced or physiological heat value of 
1 grm. of dry proteid is therefore only about 4000 calories. The fats 
and carbohydrates appear to undergo complete oxidation in the body. 

An important series of experiments on the sources of animal heat 
has been performed by Rubner.t The experiments were carried on for 
several days in succession upon a dog weighing 12 kilos. The animal 
was given a known amount of meat once a day; the urine and feces 
were collected and their heat of combustion determined, and the heat 
given off by the animal was measured by a calorimeter. At the same 
time the discharge of carbon dioxide and water from the dog were deter- 
mined, also the total nitrogen lost in the urine and feces, and the loss 
or gain in weight of the animal. No external work was done by the 
dog, for it remained quiet in the calorimeter, and therefore no energy 
was lost in the form of work. 


The following is an example of the results obtained :— 


| | 
| | 
| Heat Heat 
| Total Dis-| Carbon Calcu- Caleu- | Total Heat 
Date. | Condition. charge of from lated lated in Twenty- 
Nitrogen. Fat. from from | four Hours. 
Proteid. Fat. 
| | | 
} 
16th October 1889 | Fasting 3°06 16°38 77°0 201°5 | 278°5 kilo-cal. 
— 
This result, 278°5 kilo-calories, compares well with the heat, 276°8 kilo- 
calories, given off by the animal in the calorimeter. 
| 5 Al 
} Heat Heat Heat Lostin | Total Heat 
Date. | Condition. given to Lost in | Evaporation | in Twenty- 
Calorimeter. | Ventilation. of Water. four Hours. 
| | 
| | J | . 276'8 
16th October 1889 a ye 213°2 | 17°6 45°9 


| | kilo-cal. 


1 Ztschr. f. Biol., Miinchen, 1893-94, Bd. xxx. S. 73. 


836 ANIMAL HEAT. 


Thus it is possible to calculate the production of heat in an animal, if the 
quantity and nature of its food and the amount of the discharge of nitrogen in 
the urine and feces be known. This Rubner has done, and has compared the 
result with the heat given off by the animal to a calorimeter. Thus :— 


Food of dog during 12 days= J aan tae ee 


In the urine 30:0 germs. N were sweat and the dry feces amounted 
to 16°8 grms. 
Calculation 1, from physiological heat values. « 
Proteid, 228:06 x 4:0 kilo-cal.= 912°24 
Fat, 340°4 x9423 ,, =3207-0 


4119:2  kilo-cal. in 12 days. 


Calculation 2, from physical heat value with reduction for heat value 
of urine and feces. 


Proteid : . =1222 kilo-cal. 
at eo : . =3207 
4499 
223°5 1 
305-2 5) at ee rena of nee 
In 12 days 4124  kilo-calories. 


The amount of heat actually given off by the dog during this time was 
3958 kilo-calories. Thus the calorimeter showed that 96 per cent. of the 
energy of the food had appeared as heat. 


Recent work by Rubner! has shown that the body of a living 
animal may be looked upon as a calorimeter, and may be used as such 
for the determination of the heat of combustion of food. Thus the heat 
of combustion of 1 grm. of dry meat, determined in this way, is 4007 
calories, that of 1 grm. of dry fat 9353 calories, figures which are practic- 
ally the same as 4000 and 9423 respectively, the results obtained by 
combustion in a Thompson’s calorimeter, when allowance is made for 
the heat value of the products of the proteid lost in the urine and 
feeces. 


The following is one of Rubner’s examples of such a determination :—A 
small dog fed upon meat discharged daily 10:09 grms. of nitrogen in its urine 
and feces, and 9°06 grms. carbon from fat underwent combustion. The heat 
produced, as determined by the calorimeter, was 379°5 kilo-calories. On a diet 
of meat and fat the same dog discharged 2°95 grms. of nitrogen, and 19°12 grms. 
carbon from fat underwent combustion, while the production of heat was 311 
kilo-calories. Now, if the calorimetric value of the nitrogen be represented by 
x and that of carbon from fat by y, then— 


(1) 10:09%+ 9:06y = 379°5 
(2) 2°954+19°12y=311:0 
. ©=26°'7 kilo-calories and y = 12°15 kilo-calories, 
The results obtained by direct combustion were 26-0 and 12:3 kilo-calories. 
The heat corresponding to 1 grm. nitrogen=6°493 grms. dry meat = 26°36 
kilo-calories ; that to 1 grm. carbon from fat =1°3 erm. fat = 12°16 kilo-calories. 
1 Ztschr. f. Biol., Miinchen, 1894, Bd. xxx. S. 140. 


CHEMICAL CHANGE AND HEAT PRODUCTION. 837 


The heat of combustion of food may be determined in three ways— 
(1) by direct estimation with a calorimeter, (2) by calculation from the 
oxygen necessary for oxidation, and (5) by measurement of the heat 
produced by the combustion of the food inside the animal body. Such 
determinations have been made by Rubner,! and the following table is the 
isodynamic value of 100 grms. of fat estimated by these three modes :— 


| 


| | 
| First Method. | Second Method.| Third Method. | 
| | | | 


| 


100 grms. of Fat= 


Proteid . . | 201 | 193 Hit) 19) 
Starch . 221 | Nahe 
Cane-sugar. 231 249 | 234 
| Grape-sugar . 243 263 256 


It is to be noted that, with the exception of proteid, all food substances 
give too low a value for the heat of combustion when it is calculated from 
the equivalents of oxygen necessary for combustion. The calculation of the 
heat of combustion from the oxygen necessary for oxidation gives results 
which are not exact. 


The value of these calculations in the estimation of the heat pro- 
duced in a living body will be seen by comparing the results with those 
obtained by direct determination with the calorimeter. The following 
are Vierordt’s? calculations for the heat production of an adult man in 
twenty-four hours :— 


(a) Calculation, according to Dulong’s principle, from the heat of combus- 
tion of carbon and hydrogen. 
An adult man consumes in twenty-four hours— 


c. | H. N. 0. 


| 
rad lela SI | | | 
120 grms. proteid. : P 641s 8°60 18°88 | 28°34 | 
Soe eee oes 70-20" tee | ae 9°54 | 
330 ,, carbohydrate : 146°82 (Hydrogen | combined with oxygen) | 
281-20 | 18°86 | 18°88 
In urine and fieces : Fal 29°80 | 6°3 
\i¢ 25a th, mptOsbG 2 | | 
| | | 
251'4 grms. C. x 8,080 2 . =2,031,312 calories. 
1256 , H.x 34,460 ‘ Sy FA OLO, oe, 
Total heat production . i= 2464150). os 


1 Zischr. f. Biol., Miinchen, 1883, Bd. xix. S. 386. 
2 “Grundriss der Physiol.,” S. 281. 


838 ANIMAL HEAT. 


(b) Calculation, according to Frankland’s principle, from the heat of 
combustion of food substances — 


120 germs. proteid ' . = 599,760 calories. 
90uc ,,nutate fs LOSS l6s2 Om ee, 
Bo0) We carbohydrate } (1908 1y40eioE 
2,497,380 
4] grms. urea . E ._ = 83, 066 
Total heat production. . =2,414,314 calories. 


In the consideration of the calculations by Vierordt it is necessary 
to remember that Dulong’s principle only leads to approximate results, 
and that the values for the heat of combustion employed in the calcula- 
tion according to Frankland’s principle have been superseded by 
more recent and exact determinations. For this reason the following 
calculation is given :— 


120 grms. proteid x 4000 : A . = 480,000 
90 ,, fat x 9423 : : . = 784g 0m 
330  ,, carbohydrate x 4182 : ‘ oon =, 080,060 


Heat produced by an adult man in twenty-four hours = 2,708,130 calories, 


The calculations of other observers give the following values :— 


| 2,732,000 ids Helmholtz. 
| 2,706,076 rae Ludwig.” 


f Minimum of \ 


J : Danilewsky.? 
( nourishment Jf J 


1,800,000 


Calories for an 
adult man in 24 


( 
i ; Mixed diet— ; 
‘| 

hours . ; ‘ | 
k 


3,210,000 { Ordinary work 


= f Liberal diet— 
| 2B EO NO/ \ Hard work Jf a 
eit Liberal diet— 
po Very hard a ap 


| 2,843,000 - Rubner. 


Scharling, from direct calorimetric observation, found that an adult 
man at rest gave 132,000 calories in an hour, 3,168,000 in twenty-four 
hours; and "Hige obtained the following results, 140, 000 to 170,000 
calories per hour, 3,360,000 to 4,080,000 calories in twenty-four hours. 


THE SPECIFIC HEAT OF THE Bopy. 


The first determinations of the specific heat of animal and 
vegetable tissues appear to have been made by Crawford* The 


1 Encyclop. Worterb. d. med. Wissensch., 1846, Bd. xxxv. S. 523 

2“ Vehrbuch der Physiol.,” S. 747. 

3 Arch. f. d. ges. Physiol., Bonn, 18838, Bd. xxx. S. 175. 

4«*On Animal Heat,” 1788, 2nd edition, p. 139. Determinations were also made by 
Kirwan and Dalton. 


SEATS OF HEAT PRODUCTION. 839 


following are some of his results, and also those obtained recently by 
Rosenthal : 1— 


CRAWFORD. ROSENTHAL. 
Lean beef . . : =07740 | Compact bone . , = 0°300 
Hide of an ox with the hair =0°787 Spongy bone. ‘ = Ee 
Lungs of a sheep . : =0°769 Fat. : 3 : =0°712 
Fresh milk of acow . =0:999 | Voluntary muscle : = 0°825 
Arterial blood of a dog . =1:030 | Defibrinated blood . = (927 
Venous blood : ; = 0°8928 


It is to be noted that Davy,? Hillersohn, and Stein Bernstein? were 
unable to find any marked difference between the specific heats of 
arterial and venous blood. Recently Hale White* has made an in- 
genious attempt to obtain the specific heat of a living warm-blooded 
animal by experimenting upon a hibernating dormouse. His results 
vary between 0°812 and 1:18, but they are only approximately accurate, 
for the dormouse, even during hibernation, produces a small amount of 
heat. 

Since all the tissues of the body contain a quantity of water, the mean 
specific heat must be near unity, probably about 0°83. 


THE SEATS OF HEAT PRODUCTION. 


The work of Mayow (1674), Black (1757), Priestley (1772), 
Lavoisier (1777), and Crawford (1779)*® led to the conclusion that 
animal heat was due to a process of combustion occurring in the body, 
but concerning the chief seat of this combustion there was no unanimous 
opinion. Mayow considered that the oxidation took place in the tissues 
all over the body; Crawford held that the heat was set free chiefly in 
the capillaries of the body, owing, as he thought, to a difference in the 
specific heat of arterial and venous blood; Lavoisier was at first un- 
decided, and considered that the heat arose in the lungs, and possibly in 
other parts of the body, but finally he maintained that the lungs were 
the chief seat of combustion. The theory of Lavoisier was contested by 
Lagrange,° who maintained that if all the heat of the body were pro- 
duced in the lungs, the tissues of that organ would be destroyed by so 
high a temperature. This objection was for long held to be fatal to 
Lavoisier’s theory, until Berthelot,’ by a careful calculation, showed that, 
granting all the heat to be formed in the lungs, the temperature of those 
parts would not be raised more than a minute fraction of a degree, 
owing to the great volume of air and blood in the lungs and the rapidity 
of the circulation, whereby the heat would be quickly distributed. 
Moreover, Berthelot has shown by experiment that a small amount of 
heat is formed in the lungs by the combination of oxygen with 

1 Arch. f. Physiol., Leipzig, 1878, S. 215. 


9 


= ** Researches,” London, 1839. 

3 Arch. f. Physiol., Leipzig, 1896, S. 249. 

+ Journ. Physiol., Cambridge and London, 1892, vol. xiii. p. 789; Croonian Lectures, 
Lancet, London, June 19, 1897 ; Brit. Med. Jowrn., London. 1897, vol. i. p. 1653. 

> Mayow, ‘‘ Tractatus Quinque,” 1674 ; Black, ‘‘Lectures on Chemistry,” edited by 
Robison, Edinburgh, 1803; Priestley, Phil. Trans., London, 1772, vol. lxii. p. 147; 
Crawford, ‘‘ De Calore Animali,” 1779 ; ‘‘On Animal Heat,” 2nd edition, 1788 ; Lavoisier, 
Brit. Acad. roy. d. sc., Paris, 1777. 

§ Hassenfratz, dnn. de chim., Paris, 1791, tome ix. p. 275. 

7 Compt. rend. Acad. d. sc., Paris, 1889, tome cix. p. 776. 


840 ANIMAL HEAT. 


hemoglobin! He found in two experiments that 100 volumes of 
blood absorbed respectively 20-2 and 18:5 volumes of oxygen, and 
produced thereby 14°63 and 14:91 calories. Now, the combustion of the 
oxygen with carbon would produce 97°65 calories, but, in the formation 
of oxyhemoglobin, only 14:8 calories were set free—that is, only a 
seventh of the heat of combustion would be set free in the lungs, the 
remaining six-sevenths in the tissues. M‘Kendrick? and Bottomley 
have also been able, with a thermo-electric arrangement, to detect the 
heat produced by the union of hemoglobin with oxygen. 

The production of heat in muscle.—It has already been shown 
that during active muscular work the temperature of the body is slightly 
raised, although the loss of heat is at the same time greatly increased. 
The muscles must therefore be an important source of heat, and a 
further consideration will show that they are the chief source. The 
bulk of the body is chiefly composed of muscle; thus, in a dog weighing 
11,700 grms., the muscles weigh 5400 grms., and the bones 2400 grms. 
(Bernard) ;* and even in a much less compact animal, a bat weighing 
19-94 grms., the muscles weigh 6378 grms. (Pembrey). 

The production of heat as one of the phenomena of contraction 
in a single isolated muscle, and the relation of heat to work during a 
single contraction and during tetanus, are considered elsewhere. Here 
the muscles have to be examined as seats of heat production, not only 
during contraction, but during apparent rest; and, further, as regards 
the part they play in the production and regulation of the warmth of 
the body. 

The muscles, even when they have been removed from the body, are 
the seat of an energetic combustion (Humboldt, Liebig® Du Bois 
Reymond, Valentin,’ Matteucci®). The following comparative experi- 
ments were made by Paul Bert.® Different tissues were removed from 
a dog just killed, and the absorption of oxygen and discharge of carbon 
dioxide were determined during a period of twenty-four hours, at a 
temperature varying from 0° to 10° :— 


100 grms. of muscle absorbed 50°8 ¢.c, of oxygen, and discharged 56°8 c.c. of carbonic acid. 
a brain By 45°8 ¥ Le 42°8 ‘3 
2) kidney 9 37°0 ” 9 15 6 29 
ifs spleen - 27°3 = 5 15:4 a 
or) ha 1 ye) 18°3 2? ” 27°5 2? 
roken bone ¥ 
3 and marrow t ee ae ae a 2? 


Regnard? has shown that the respiratory exchange of isolated muscle rises 
and falls with the external temperature ; at 10° the discharge of carbon dioxide 
by 1 kilo. of muscle is 40 c.c. in one hour, at 25° it is 129 e.c., and at 35° it 
amounts to 294 ¢.c., but above 40° the discharge decreases. 


‘See also Davy, “‘ Researches,” London, 1839, vol. ii. p. 168. 

2 Brit. Med. Journ., London, 1888, vol. ii. p. 338. 

3 «<Tecons sur la chaleur animale,” 1876, p. 140. 

4 Journ. Physiol., Cambridge and London, 1895-96, vol. xix. p. 485. 

» “ Versuche ueber die gereizte Muskel-und Nervenfaser,” Berlin, 1797. 

§ Arch. f. Anat., Physiol. u. wissensch. Med., 1850, S. 393. 

? Arch. f. physiol. Heilk., Stuttgart, 1855, Bd. xiv. S. 431. 

SCompt. rend. Acad. d. sc., Paris, 1856, tome xlii. p- 648; Ann. de chim. et phys., 
Paris, 1856, tome xlvii. p. 129. 

*** Lecons sur la physiol. comparée de la respiration,” 1870, p. 46. 

*° «Recherches expérimentales sur les combustions respiratoires,” Paris, 1879, p. 23. 


PRODUCTION OF HEAT IN MUSCLE. 841 


Similar results have been obtained by Rubner! in limbs through which an 
artificial circulation of blood was maintained. 

Although, as Hermann? has shown, some of the carbon dioxide may arise 
from the action of bacteria, yet these experiments show that even excised 
muscle is the seat of an energetic metabolism and of heat production. Tissot * has 
proved that the absorption of oxygen and the discharge of carbon dioxide occur 
in an excised muscle, even when every precaution is taken to maintain asepsis. 
The results of Minot’s+* experiments upon the production of carbon dioxide in 
resting and active muscle are opposed to those obtained by Paul Bert and 
Regnard, but his method has been shown by Zuntz® to be open to serious 
objections. 

The subject of respiration in muscle will be discussed more fully in other 
parts of this work,® here it is only necessary to point out that the respiratory 
exchange of a muscle, even during apparent rest, is very marked, and becomes 
enormously increased during activity. This is well shown by the experiments 
of Sezelkow,’ von Frey, Chauveau and Kaufmann,’ Hill and Nabarro.!° 


DIFFERENCE BETWEEN VENOUS AND ARTERIAL BLOOD. 
Muscle at Rest. | Muscle Active. 
(ico, +671 | +3237 
Sczelkow | 
| O, —9:00 — 36°78 
( CO, +8°70 | +30°60 
Chauveau and Kaufmann - | 
(co: ~ 11°40 — 40°95 
| Tonic. Clonic. 
co, | +8°76 |; -+41°70 +57°99 
Hill and Nabarro . Jae 
LV. 6; ~ 12°92 -41°25  —87°89 


i 


The muscles during apparent rest are in a state of tone, and are the seat of 
an energetic combustion, and therefore of heat production. 


Further evidence of the important part played by the muscles in the 
production of heat is found in the fact that any cause which suspends 
the activity of the muscles, or more correctly the neuro-muscular 
system, lowers the temperature of the body. Curari causes muscular 
paralysis and a fall in the temperature of the body ;"™ the respiratory 
exchange is greatly diminished, even if the animal’s temperature is 


1 Arch. f. Physiol., Leipzig, 1885, 8S. 38; this Text-book, article ‘‘Chemistry of 
Respiration.” 

2 <Untersuch. u. d. Stofiwechsel der Muskeln,” Berlin, 1867, S. 37. 

° Arch. de physiol. norm. et path., Paris, 1894, tome xxvi. p. 838; 1895, tome xxvii. 

+ «* Die Bildung der CO, innerhalb des ruhenden und erregten Muskeln.” 

° Hermann’s ‘‘ Handbuch,” Bd. iv. Th. 2, S. 96. 

® See articles on ‘‘ Chemistry of Respiration” and on ‘‘ Metabolism,” this Text-book, 
vol. i. 

7 Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1862, Bd. xlv. 

8 Arch. f. Physiol., Leipzig, 1885, S. 533. 

° Compt. rend. Acad. d. sc., Paris, 1886, tome cili. pp. 974, 1057, 1153. 

0 Journ. Physiol., Cambridge and London, 1895, vol. xviii. p. 218. 

1 Tscheschichin, Arch. f. Anat. Physiol. u. wissensch. Med., 1866, S. 159. During 
the convulsions which are at first caused by curari the temperature rises; Bernard, 
**Tecons sur la chaleur animale,” 1876, p. 157; Velten, Arch. f. d. ges. Physiol., Bonn, 
1880, Bd. xxi. S. 361. 


842 ANIMAL HEAT. 


artificially maintained at the normal height.1 These experiments have 
been extended by Pfliiger,2 who found im curarised rabbits that the 
intake of oxygen and the output of carbon dioxide fell respectively to 
35-2 and 37-4 per cent. of the normal exchange: a rise in the tempera- 
ture of the surroundings caused an increase in the respiratory exchange, 
and in the temperature of the animal, whereas a fall in the external 
temperature produced the opposite effects. These phenomena were not 
due to diminished supply of oxygen, for artificial respiration was 
maintained, the heart beat strongly, and the venous blood was brighter 
than in the normal animal. Further, it is not due to poisoning of the 
muscle substance itself, for Colasanti? found that the oxidation in the 
muscles of a limb with an artificial circulation was the same whether 
the blood did or did not contain curari. Similar results have been 
obtained with anesthetics and drugs which depress the activity of the 
nervo-muscular system.+4 

It will be shown later that section of the spinal cord or of the 
motor nerves reduces a warm-blooded animal to a cold-blooded condition ; 
its temperature falls, and it can no longer regulate its temperature. 
The completeness of the effect seems to depend upon the number of the 
muscles paralysed. On the other hand, calorimetric determinations 
show that muscular activity greatly increases the production of heat 
and the respiratory exchange. 

It has already been stated that young mammals and birds, in which 
muscular co-ordination is well developed, are able to maintain their 
temperature at birth, whereas others born in a helpless condition 
resemble cold-blooded animals. 

According to D. Macalister,> the muscles are fatigued as producers of 
heat sooner than as producers of work, and the effect of cold upon the 
muscles of anesthetised mammals is to markedly depress the thermo- 
genic function. 

The involuntary muscular contraction in shivering causes a rise 
of temperature® and this is especially noticeable in small thin dogs 
with little fur; in fact, shivering must be looked upon as an involuntary 
protective mechanism against cold.7 In man, as Lowy ® has shown, it 
may increase the metabolism by 100 per cent. The warming effect of 
muscular exertion is a matter of ordinary daily experience, and is well 
shown by the difference in the walk of a man during cold and hot 
weather. 

The heat produced by the contraction of the heart.—The work 
done by the human heart was estimated by Gréhant® at 43,800 kilo- 
grammetres in twenty-four hours, and this according to the mechanical 

Ped 
43800 = 103,000 calories. Foster? eal- 


_ 


culates that the work done by the heart is nearly 60,000 kilogrammetres, 


1 Zuntz, Arch. f. d. ges. Physiol., Bonn, 1876, Bd. xii. S. 522. 

* Thid., 1878, Bd. xviii. S. 255. 

3 [bid., 1878, Bd. xvi. S. 157. 

4 Rumpf, ibid., 1884, Bd. xxxiii. S. 538; Pembrey, ‘‘ Proc. Physiol. Soc.,” Journ. 
Physiol., Cambridge and London, 1894-1895, vol. xvii. 

5 **Goulstonian Lectures,’ Lancet, London, 1887, vol. i. p. 558. 

6 Béclard, Arch. de méd. nav., Paris, 1861, pp. 24, 157, 257. 

7 Richet, Compt. rend. Soc. de biol., Paris, 1892, p. 896. 

8 Arch. f. d. ges. Physiol., Bonn, 1889, Bd. xlv. S. 625 ; and 1890, Bd. xlvi. S. 189. 

9 “* Phys. Méd.,” 1869, p. 229. 

10 « Text-Book of Physiology,” 1891, 5th edition, pt. 1, p. 254. 


equivalent of heat would give 


PRODUCTION. OF HEAT IN. GLANDS. 843 


Waller! estimates it at 20,000 kilogrammetres, and Nicolls? at 54,000 
kilogrammetres. 

The production of heat in glands.—Glands are the seat of active 
chemical changes, accompanied by a production of heat, but during 
activity their blood supply is augmented, and the increased temperature 
arising from this cause often masks the heat produced by the activity 
of the glands. 

The submaxillary gland is an instance in which the activity of the 
tissue is accompanied by a greatly increased blood flow. Ludwig and 
Spiess? found by the thermo-electric method that the submaxillary 
saliva of a dog was 1° to 1°°5 warmer than the blood in the carotid 
artery. Bernard #ligatured the blood vessels of the gland, and found that 
stimulation of the chorda tympani still produced a slight rise in temper- 
ature, whereas excitation of the sympathetic produced a slight fall. The 
temperature in degrees is not stated, but Bernard brings these observations 
forward as additional arguments in favour of frigorific nerves. Morat ° 
states that he has been able to confirm Bernard’s results; Heidenhain,® on 
the other hand, observed a rise in temperature when the sympathetic was 
stimulated. Recently, Bayliss and Hill’ have carefully investigated 
the question of the formation of heat in salivary glands; they used both 
the thermo-electric method and Geissler’s thermometers. Their results 
led them to the following conclusions :—The temperature of the gland 
and tissues around it is almost as high as that of the aortic blood; the 
saliva is not warmer than the gland and tissues around the duct, and no 
formation of heat can be directly determined in the submaxillary gland 
by any known method of measuring variations in temperature. On 
stimulation of the chorda tympani, the temperature of the saliva never 
rose bigher than the temperature of the aortic blood. No doubt the 
gland produces more heat during activity, but, on account of the small 
size of the gland, and the rapid circulation, the difference cannot be 
shown. 

The intestines and liver—According to Bernard, the blood coming 
from the intestines is raised Im temperature during digestion, the tem- 
perature of the blood in the portal vein being two- or three-tenths of a 
degree warmer than that of the abdominal aorta. Bernard also found 
that the liver was the warmest organ in the body, that the blood of the 
hepatic vein was higher than that of the portal vein, and showed a still 
further increase during digestion. 

Stimulation of the splanchnic, or of the vagi nerves, produces no 
calorific or frigorific effect in the temperature of the liver.® 


1 «* Human Physiology,” 1893, 2nd edition, p. 75. 

2 Journ. Physiol., Cambridge and London, 1896, vol. xx. p. 407. 

3 Sitzungsh. d. k. Akad. d. Wissensch., Wien, 1857, Bd. xxv. S. 584; Ludwig, Wien. 
med. Wehnschr., 1860, Nos. 28 and 29. 

4“ Tecons sur la chaleur animale,” 1876, p. 428. 

® Arch. de physiol. norm. et path., Paris, 1893, tome xxv. p. 285. 

§ Stud. d. physiol. Inst. zu Breslau, Leipzig, 1868, Bd. iv. 

* Journ. Physiol., Cambridge and London, 1894, vol. xvi. p. 351. 

8 «* Tecons sur la chaleur animale,” 1876, p. 190. See also this article, p. 809; Braune, 
Virchow’s Archiv, 1860, Bd. xix. S. 470, 491. 

9 Waymouth Reid, ‘‘ Proc. Phys. Soc.,” Journ. Physiol., Cambridge and London, 1895, 
vol. xviii. 


844 ANIMAL HEAT. 


THE MEASUREMENT OF HEAT PRODUCTION. 


The amount of heat produced by an animal can be determined by 
the measurement of the heat given off, and also by an estimation of the 
heat value of the chemical changes taking place in the body. The most 
exact method is that which embraces both of these determinations. 

Numerous attempts have 
TU been made to construct 
CBA & : 
ay suitable calorimeters, but 
‘gs it is only within the last 
few years that exact 
methods have been de- 
vised. 


Calorimeters.'—In 
1780, Lavoisier and Lap- 
lace ? employed the ice cal- 
orimeter, in which the heat 
produced by the animal is 
estimated from the amount 
of ice liquefied. The con- 
struction of this calorimeter 
is shown in the accompany- 
ing diagram. (Fig. 81). 

Important results were 
| obtained by the use of this 

Se ol method, but they were not 
WMMVJJJJYuw@WU an exact measure of the 


Fic. 81.—Diagram of ice calorimeter. heat produced by a normal 

animal, The exposure to 

such a low temperature causes an abnormal loss and production of heat, and 

it is impossible to rapidly and completely collect the water formed by the 
melting of the ice. 

Crawford,’ in 1788, introduced the water calorimeter, and indicated the 
precautions necessary to obtain accuracy. The method was improved by 
Dulong and Despretz. 

Although this calorimeter was a great advance upon the ice calori- 
meter, yet it has been found by numerous observers to be unreliable. It 
is impossible, even by careful mixing, to obtain the exact heat of the water, 
for strata of different temperatures are formed, and thus errors easily 
arise. Further, the water responds very slowly to any change in the 
production of heat by the animal. This method was used by Dulong? 
and Despretz,? and has been again brought into use by Wood, Reichert, 
and others.® 

The air calorimeter appears to have been first used by Scharling‘ in 1849, and 


(ely 
-<¥ SES aes J 


WY ia 


1 A list of researches in which different kinds of calorimeters have been used, will be 
found in the paper by Haldane, Hale White, and Washbourn, Jowrn. Physiol., Cambridge 
and London, 1894, vol. xvi. p. 124. 

2 Hist. Acad. roy. d. sc., Paris, 1780, p. 355. 

5 « Experiments and Observations on Animal Heat,” London, 1788, 2nd edition. 

+ Ann. de chim. et phys., Paris, 1843, Sér. 3, tome i. p. 440; Compt. rend. Acad. d. 8¢., 
Paris, tome xviii. p. 327. 

5 Ann. de chim. et phys., Paris, 1824, Sér. 2, tome xxvi. p. 337. 

6 Wood, ‘‘ Fever,” Smithson. Contrib. Knowl., Washington, 1880; Reichert, Univ. 
Med. Mag., Philadelphia, 1890, vol. ii. p. 173. 

7 Journ. f. prakt. Chem., Leipzig, 1849, Bd. xlviii. 8. 435. 


CALORIMETERS. , 845 


the most exact of the modern methods are modifications of this.! D’Arsonvyal,? 
in 1886, introduced the differential air calorimeter, which has this great advan- 
tage, that the loss of 
heat by conduction 
and radiation from 
the calorimeter con- 
taining the animal is 
compensated by a 
similar loss from a 
dummy calorimeter of 
similar size and con- 
struction. This 
method has been em- 
ployed, and still fur- 
ther modified, by 
Rosenthal*® and 
Rubner,? but it will 
suffice here to describe 
only the latest form, 
that introduced by 
Haldane, Hale White, 
and Washbourn.® In 
this calorimeter (Fig. 
85) the heat produced 
by the animal in one 
chamberis balanced by Fic. 82.—Diagram of Dulong’s water calorimeter. 

the heat given off by a 

hydrogen flame burning in another similar chamber. The amount of hydrogen 
burnt is estimated, and, 
knowing the heat of 
combustion of hydro- 
gen, one can calculate 
the calories produced 
by the quantity of 
hydrogen used in the 
experiment ; this num- 
ber of calories is equal 
to those given off by 
the animal. The cal- 
orimeter is so arranged 


| = ae ers 


Fic, 83.—Diagram of air calorimeter (Haldane, Hale 


White, and Washbourn). that at the same time 
1t serves aS a respira- 

F. Layer of felt. A. Tubes for ventilation. 
C. Cage. H. Hydrogen flame. toayean Jes dase ee 
M. Manometer. determination of 


the intake of oxygen 
and output of carbon dioxide checks the result of the calorimetric observa- 
tion. 


? Rosenthal, Arch. f. Physiol., Leipzig, 1878, S. 349; Richet, Arch. de physiol. norm. 
et path., Paris, 1885, tome vi. p. 237 ; Mosso, Arch. f. exper. Path. u. Pharmakol., Leipzig, 
1890, Bd. xxvi. S. 316. 

2 Journ. de Vanat. et physiol. ete., Paris, 1886, tome xxii. 

3 Arch. f. Physiol., Leipzig, 1888, S. 1. 

4 *<Calorimetrische Methodik,” Marburg, 1891; Beitr. z. Physiol. Carl Ludwig 
; s. 70 Geburtst., Leipzig, 1887; Ztschr. f. Biol., Miinchen, 1893-94, Bd. xxx. 

92, 

° Journ. Physiol., Cambridge and London, 1894, vol. xvi. p. 123; Hale White, 
en Lectures, Lancet, London, 1897, vol. ii. ; and Brit. Med. Journ., London, 1897, 
WHe AEs pal 


846 ANIMAL HEAT. 


For experiments on man, Currie,! and afterwards Liebermeister * and others, 
used a bath as a water calorimeter ; this method is liable to many sources of 
error. Scharling,® Vogel, and Hirn ° used a method which was simple, but at 
the same time untrustworthy ; the subject of the experiment was enclosed 
within a small chamber standing in a room with a constant temperature ; the 
production of heat was determined from the difference between the tempera- 
ture of the chamber and that of the room. Leyden employed a _ partial 
calorimeter for experiments in man ; a limb was enclosed in a suitable water 
calorimeter. 

It is probable that the simplest and most useful method for clinical 
purposes is that introduced by Waller ®; the deep and surface temperatures 
of different parts of the body are determined, the evaporation of water from 
the skin is estimated by a hygrometer, and the temperature of the surrounding 
air is noted. If the calorimetric value of the thermometer scale be pre- 
viously determined on a surface giving off heat at a known rate, it is possible 
from the data obtained to calculate the emission of heat. The apparatus, in 
fact, constitutes a heat manometer measuring the temperature difference 
between the skin and atmosphere. 


The results of calorimetric experiments.—Lavoisier’ and Craw- 
ford § concluded from their results that the heat produced by an animal 
could be almost entirely accounted for by the combustion represented 
by the discharge of carbon dioxide and water. Dulong® and Despretz’s 
data, when corrected by Liebig,'' Helmholtz,’ Gavarret, Ludwig,4 Milne 
Edwards,” and Liebermeister,!® lead to a similar conclusion, but since the 
more exact experiments of Rubner and others, they have had only a 
historical interest.!” 

The table on p. 847 gives some of the more important results 
obtained by various observers. 

It has been already shown that the heat, measured directly with a 
calorimeter, is equal to that calculated from the heats of combustion of 
the constituents of the food (Rubner }8), and it will be seen later that the 
production of heat in different warm-blooded animals is proportionate to 
the surface of their bodies (Rubner).!® During digestion and muscular 
work the production of heat is greatly increased. 

According to Langlois,?? the production of heat in children is pro- 
portionate to the surface of their skin, and shows a daily variation. 


1‘ Medical Reports on the Effect of Water, Cold and Warm, as a Remedy in Fever and 
other Diseases,” Liverpool, 1798. 

2 Arch. f. Anat., Physiol. wu. wissensch. Med., 1860, S. 520, 589; 1861, S. 28; ‘* Hand- 
buch der Path. u. Therap. des Fiebers,” 1875, 8S. 142. 

3 Journ. f. prakt. Chem., Leipzig, 1849, Bd. xlviii. S. 435. 

4 Arch. d. Ver. f. wissensch. Heilk., Leipzig, 1864, S. 442. 

5 «* Recherches sur ]’équivalent mécanique de la chaleur,” Paris, 1858. 

6 «* Proc. Physiol. Soc.,” Journ. Physiol., Cambridge and London, 1894, vol. xv. 

7 Hist. Acad. roy. d. sc., Paris, 1780, p. 355. 

8 «* Experiments and Observations on Animal Heat,” 1788, 2nd edition. 

9 Ann. d. chim. et phys., Paris, 1843, Sér. 3, tome i. p. 440. 

10 Jbid., 1824, Sér. 2, tome xxvi. p. 337. 

11 «*« Thierchemie.” S. 28. 

12 «* Eneyclop. Worterb. d. med. Wissensch.,” 1846, Bd. xxxv. 8. 523. 

18 «De la chaleur produite par les étres vivants,” 1855, p. 219. 

14 «*Tehrbuch d. Physiol.,” 1861, Aufl. 2, Bd. ii. S. 739. 

15 “ Tecons sur la physiologie,” 1863, tome viii. p. 23. 

16 “¢ Handbuch der Path. u. Therap. des Fiebers,” 1875, S. 134. 

17 For a discussion of these results see Rosenthal, Hermann’s ‘‘ Handbuch,” Bd. iv. Th. 2, 
8. 358. 

18 Ztschr. f. Biol., Miinchen, 1894, Bd. xxx. S. 135. This article, pp. 833-37. 

19 Ztschr. f. Biol., Miimchen, 1883, Bd. xix. S. 535. This article, p. 853. 

2 Centralbl. f. Physiol., Leipzig u. Wien, 1887, S. 237. 


MEASURE OF HEAT PRODUCTION. 847 


0 
| 5350—5450 grms. 


| 
Heat Produced. Animal. Remarks. | Observer. | 
132,000 cal. per hour. | Adult man. At rest. | Scharling.! 

/ 140,000 ,, AP pe eee eA | Hirn.? 
99,000 ,, PB pee erie Partial calorimeter | Leyden.* | 
used. | 
21,000 cal. per hour. | Dog weighing One hour after food. | Senator.4 | 
| 


1276380 ,, - a | Twenty-six hours 
| after food. 
10,900 ,, iss o About forty-nine | ie 
hours after food. | 
| 
2,500 cal. per hour and | Dogs. About thirty-six | 
per kilo. | hours after food. 
Mean of experiments. 
| on six dogs. 
5,920 cal. per hour and | Pigeon. Normal. Corin and Van | 
| per kilo. | | Beneden.? 
6,000, ei or | After removal of | 
cerebral hemi- 
spheres. | 


The respiratory exchange as a measure of heat production.— 
The heat of the body has been shown to be due to processes of com- 
bustion occurring in the tissues. The respiratory exchange is a measure 
of this combustion, and hence a determination of the intake of oxygen 
and the output of carbon dioxide is a measure, although not a perfectly 
accurate one, of the heat produced. There is, however, one source of 
inaccuracy in this method ; a determination of the respiratory exchange 
during a limited time is not an exact indication of the combustion oceur- 
ring during that time, for we know that oxygen may be taken up and 
stored in the body for a considerable period, and carbon dioxide may be 
given off by the breaking up of previous combinations ; in fact, may still 
be evolved when the tissues are receiving no free oxygen. Nevertheless, 
consecutive determinations of the respiratory exchange for long periods, 
and careful observations of the animal’s temperature, form a most valu- 
able method for the study of the regulation of temperature by heat 
production, especially since calorimetric experiments are more tedious, 
difficult, and more open to accidental sources of error. 

In the case of warm-blooded animals, a fall in external tempera- 
ture increases, a rise diminishes the intake of oxygen and the out- 
put of carbon dioxide. Crawford® and Lavoisier? came to this 
conclusion not only on theoretical grounds, because they believed that 
animal heat was due to combustion, but from the results of direct 
experiment. 


1 Journ. f. prakt. Chem., Leipzig, 1849, Bd. xlviii. S. 435. 

2 “Recherches sur l’équivalent mécanique de la chaleur,”’ Paris, 1858; ‘‘ Exposition 
analytique et expérimentale de la théorie mécanique de la chaleur,” Paris, 1875, 3e édition, 
tome i. p. 27. 

: Bethe Arch. f. klin. Med., Leipzig, 1869, Bd. v. S. 273. 

4 Centralbl. f. d. med. Wissensch., Berlin, 1871; Arch. f. Anat., Physiol. u. wissensch. 
Med., 1872, S. i. ; 1874, S. 18; ‘* Untersuch. ueber den fieberhaften Process und seine 
Behandlung,” Berlin, 1873, S. 30. 

° Arch. de biol., Gand, 1887, tome vii. p. 276. 

6 “ Experiments and Observations on Animal Heat,” 1788, 2nd edition. 

” Hist. Acad. roy. d. sc., Paris, 1780, p. 407. 


848 ANIMAL HEAT. 

Numerous observations have been made, chiefly by Pfliiger and his 
pupils, upon the effect of changes in external temperature upon the 
respiratory exchange of animals in normal and abnormal conditions. 
The results of some of the most important experiments will now be 
given :! — 


Ae DERE, Intake of Oxygen. Me aS Aaa ‘ = Animal. Observer. 
4°°4 210°7 germs. in 6 Man Voit.? 
hours. weighing 
6°°5 206°0 HY [ed 71 kilos. 
9°°0 192°0 % are 
14°°3 155-1 Si 
93°°7 | 164:8 _ 
26°°7 160-0 2 
30°°0 170°6 : 
7°°3 | 1496°66 c.c. per hour | 1203°44 c.c. , 0°80 | Guinea- Colasanti.® 
| and kilo. | pig. 
16°°9 | 1086°8 % 937°01 ,, | 0°86 
| 
3°°64 | 1856°8 1564°8 ,, | 0°83 | Guinea- Finkler.4 
96°21 | 1118°5 i 1057-4, 0:94 | pig. 
— 5°°5 17°48 grms, in 6 hours IS: 83ir. Cat Herzog 
2°0 15°79 - Le Silmenss weighing | Car] 
D8} eral J G3 about 2°5 | Theodor.? 
20°] 12°78 4 14°34 ,, kilos. 
29°°6 13°91 in 13°12 ,, 
-9°0 3016 ¢.c. perhour | Pigeon. Corin and 
and kilo. Van Bene- 
TPP 1141 ne den.® 


It will be seen from the above table that the respiratory exchange 
decreases with a rise in external temperature, until a point about 35° 
is reached, when an increase in the metabolism occurs.’ The response 
to a change in temperature is, in the case of small mammals, almost 
immediate. Thus, within two minutes of a change from 30° to 18°, 
a mouse increased its output of carbon dioxide by 74 per cent. ; within 
one minute of a change from 33°25 to 17°°5 the increase was 60 per 
cent. The response to an increase in temperature does not take place 
so quickly; thus, within two minutes of a rise from 18° to 34°, 
the decrease in the output of carbon dioxide was 18 per cent. ; 
within one minute of a rise from 17° to 32°, the decrease was 5 
per cent. The power of maintaining a constant mean temperature is 
readily tested in this manner, as the following example will show 
(Pembrey) :— 

1 See also the preceding article on ‘‘ Chemistry of Respiration.” 

2 Ztsehr. f. Biol., Miinchen, 1878, Bd. xiv. S. 57. 

3 Arch. f. d. ges Physiol., Bonn, 1877, Bd. xiv. S. 92. 

4 Ibid., 1877, Bd. xv. S. 603. 

5 Ztschr. f. Biol., Miinchen, 1878, Bd. xiv. 8S. 51. 

6 Arch de biol., Gand, 1887, tome vil. p. 274. 

7See also Page, Journ. Physiol., Cambridge and London, vol. ii. 
‘‘Chemistry of Respiration,” this Text-book, vol. i. p. 712. 


8 Pembrey, Jowrn. Physiol., Cambridge and London, 1894, vol. xv. p. 401. 
‘Chemistry of Respiration,” this Text-book, vol. i. 


p- 228; and 


See also 


PRODUCTION OF HEAT IN COLD-BLOODED ANIMALS. 849 


Consecutive Periods of Thirty Minutes. 


30. ir xte 
| Dacia Geatnmce marsparnehnd Bema, 

1055 11°°0 Mouse shivering and active, face and ears pale. 
957 THO Mouse less active, ears pale. 
518 31-5 Mouse quiet, sweating, ears flushed. 
262 320° Mouse sprawled out, sweating, apparently asleep, 
815 TS <0 Mouse wakes up, becomes very active, ears pale. 
683 11°:0 Mouse quiet, ears pale. 


THE PrRopucTION OF HEAT IN CoLp-BLOODED ANIMALS. 


One of the most characteristic phenomena of life is an exchange of material, 
an oxidation which results in the production of heat. In the lowest forms of 
life, both vegetable and animal, a certain amount of heat is produced. 
Numerous experiments have shown that this is so, although, owing to the 
cooling effect of evaporation from the surface of the body, the heat produced 
may be masked by the excessive loss; the temperature of a frog may be 
lower than that of the air, notwithstanding that the animal is constantly 
producing heat. 

It is unnecessary to give here an account of the temperature of plants,! 
but, in addition to the facts already stated,? further details must be brought 
forward concerning the production of heat in the lower animals. Hunter 2 
found that the temperature of earth-worms, slugs, and leeches might be a degree 
above that of their surroundings ; a carp had a temperature of 20°-6, a viper 
one of 20°, when that of the surroundings was 18°-6 and 14°-4 respectively. 

In bees, even in winter, the capacity for producing heat has already been 
shown to be very great. Next in point of interest is the fact, to which 
attention was first drawn by Valenciennes,# that pythons, when coiled 
round their eggs during incubation, maintain a temperature even 20° 
above that of the surrounding air. The following are some of the results 
obtained by Sclater,® who compared the temperature of a female python with 
that of the non-incubating male, which was kept in the same compartment of 
the reptile house :— 


| | 
Dates. ee a Temperature of Male. Temperature 
| On surface, 217-2 22°+8 
| Feb. 12 14°°8 
Between folds, 23°°8 25 
On surface, 22°°0 28°°9 
March 2 15°°6 | 
Between folds, 24°°4 35°°6 | 


1 See on this subject Dutrochet, Ann. d. se. nat., Paris (Botanique) 1840, Sér. 2, tome 
xiii. pp. 5 and 65 ; Gavarret, ‘‘ De la chaleur produite par les étres vivants,” Paris, 1855, 
p- 516; Sachs, ‘‘ Physiology of Plants,” p. 404; Vines, ‘‘ Physiology of Plants”; Van 
Tieghem, ‘‘ Traité de botanique,” Paris, 1891, tome i. It is interesting to notice that an 
abnormal rise of temperature, fever in fact, has been observed in the tissues around a 
wound in a plant.—Annals of Botany, 1897. 

2 This article, p. 792. 

3 «* Works,” Palmer’s edition, London, 1837, vol. iv. p. 131 et seq. 

* Compt. rend. Acad. d. sc., Paris, 1841, tome xiii. p. 126. 

° Proc. Zool. Soc. London, 1862, p. 365. 


VOL. I.—54 


850 ANIMAL HEAT. 


Forbes ! made similar observations, and found, as the average temperatures 
between the folds of the body, 30° and 31°°7 in the case of the male and 
female respectively; the maximum was 32°:1 for the male, and 33°°8 for 
the female. The greatest difference between the temperature of the air and 
the surface of the snake was 4°°6 in the male, and 5°°3 in the female; between 
the air and the coils of the snake, 6°°4 in the male, and 9°:3 in the female. It 
is worthy of note that the female took no food and little exercise for many 
weeks before and during incubation. 

In some fishes a temperature several degrees above that of the water has 
been observed. Thus Davy? found the temperature of deep-seated muscles of 
the bonito (Thynnus pelamys) to be 37°:2, when that of the sea was 26°°9. 
The tunny (Thynnus thynnus) is said to have a similar high temperature. 

The embryo of the chick must be looked upon as a cold-blooded animal, 
for it responds to changes of temperature in a similar manner,’ yet even at an 
early stage the production of heat within its tissues can be shown to be 
considerable. Thus Barensprung‘ found that the temperature of an egg on 
the fourth day of incubation was *6 above that of a dead egg and ‘8 above 
that of the incubator. 


THE REGULATION OF LOSS OF HEAT. 


An animal may lose heat in various ways—by direct conduction and 
radiation from the skin, by evaporation of sweat, by the warming of air 
during respiration and by evaporation from the different parts of the 
respiratory system, by raising cold food and drink to the temperature 
of its body, and by the discharge of urine and feces. Loss of heat is 
controlled chiefly by the skin and the lungs. 

The distribution of the loss of heat by an adult man in twenty-four. 
hours has been estimated by various observers as follows :— 


Vierordt. Helmholtz. Ludwig. 
1] 18 %by urine and feces = 47,500 calories,| = 26% Paes 
2} 35% by expired air ~~ = i — PP Ebi/ T2244 ioe 
3 | 7-2% by evaporation from lungs = 182,120 |, =14°7 Z \ 2,782,000 |) 19.3 2,706,076 
411457 , » skin = 364,120 ,, ) calories. |f ° [ calories. 
5 | 73°04 by radiation and conduction =s0 7 

froin skin “2008 Ysa 1) ) Us= Ml, YORO20 em ceeds 78:5 
2,500,000 


Loss of heat by the skin—Radiation and conduction. — The 
amount of heat lost by radiation and conduction is, within certain 
limits, in proportion to the difference in the temperature of the body 
and of its surroundings; the warmer the skin and the colder the 
surroundings, the greater will be the loss of heat. The heat of the skin 
is controlled by the cutaneous circulation, and this in turn is regulated 
by the central nervous system. The general result is that the cutaneous 
blood vessels are contracted, the circulation is smaller, and the skin 
pale and cold, when the external temperature is low; on the other 
hand, the vessels dilate, the circulation becomes greater and the skin 
red and warm, when the temperature of the surroundings is high. 


1 Proc. Zool. Soc. London, 1881, p. 960. 

2 «« Researches,” London, 1839, vol. i. p. 219. 

3 Pembrey, Gordon, and Warren, Journ. Physiol., Cambridge and London, 1894-95, 
vol. xvii. p. 331. 

4 Arch. f. Anat., Physiol. u. wissensch. Med., 1851, S. 131. 


REGULATION BY EVAPORATION. 851 


Thus it happens that the animal can diminish or increase its loss of heat 
according to its needs. 

Other conditions, however, play an important part in this regula- 
tion. In the case of man the epidermis and the subcutaneous fat are 
bad conductors; and, by means of clothing,! the greater part of the body 
is so protected that it is in contact not with the external air, but with 
a fairly stationary layer of air, with a temperature from 24° to 30°. In 
other warm-blooded animals protection is afforded by the fur or feathers, 
which prevent loss of heat not only by their thickness and slight. power 
of conduction, but by enclosing strata of more or less stationary warm 
air. The more stationary the air the less the loss of heat, for the body 
becomes surrounded with a layer of air having a temperature inter- 
mediate between that of the body and of the atmosphere. Thus, during 
Parry’s expedition to the Polar seas, the sailors found that they could 
better bear a cold which would freeze mercury (—40°), when the air 
was perfectly calm, than a temperature of —12°:2 when there was a 
wind.? The men of Franklin’s expedition had the same experience.* 
Further, the capacity of dry air to take up heat is much less than that 
of moist air; hence it happens that in dry, calm air several degrees below 
zero, much less sensation of cold may be felt than in moist air with a 
temperature a few degrees above the freezing point. 

In the whale, seal, and walrus, the thick epidermis and the large 
amount of subcutaneous fat so perfectly prevent excessive loss of heat, 
that their high temperature can be maintained in the Arctic seas. 
Greyhounds, on the other hand, feel even moderately cold weather very 
quickly, for, as the result of selective breeding, they have little fur and 
hardly any subcutaneous fat. Vierordt® calculated that an adult man 
lost 1,791,820 calories, or 73 per cent. of the total loss of heat, by 
radiation and conduction from the skin in twenty-four hours. Masje,® 
from experiments made with a thermoscope, constructed on the principle 
of Langley’s bolometer, concludes that the heat lost by radiation from 
the skin of an adult man, weighing 82 kilos. and with a surface of 
20,000 square cms., is 1,700,000 calories in twenty-four hours. Similar 
experiments have also been made by Stewart.? 

Hvaporation.— Benjamin Franklin * observed, during the hot weather 
at Philadelphia in 1750, that his temperature remained normal, although 
the external temperature was 37°8 in the shade. He attributed this 
result to the cooling effect of the evaporation of sweat. This was proved 
by Blagden * during his experiments upon the effect of extreme heat on 
the body. When the air was moist, the temperature of the body rose; 
whereas in dry air, heated to 126°, the temperature did not rise above 
the normal. Into the heated room two jars of water were brought, and 
a layer of oil was placed on the surface of the water in one, with the 


1Schuster, Arch. f. Hyg., Miinchen u. Leipzig, 1888, Bd. viii. S. 1; Rubner, 7bid., 
1890, Bd. xi. S. 255. 

2 «* Journal of a Second Voyage to the Arctic Regions.” 

3 Franklin, ‘‘ Journey to the Polar Sea, 1819-1822,” 2nd edition, vol. ii. pp. 27, 28. See 
also Ross, ‘‘ Narrative of a Second Voyage in Search of a North-West Passage,” London, 
1835, pp. 285, 287, 297. 

4 Bergmann, ‘‘ Gottinger Studien,” 1847, Abth. 1, S. 595. 

® **Grundriss der Physiol. des Menschen.” 

5 Virchow’s Archiv, 1887, Bd. evii. S. 17, 267. 

7 Stud. Physiol. Lab. Owens Coll., Manchester, 1891, vol. i. p. 100. 

8 «Experiments and Observations on Electricity,” London, 1769, p. 366. 

° Blagden, Phil. Trans., London, 1775, vol. lxv. pp. 111 and 484. 


852 ANIMAL HEAT. 


result that it quickly boiled, owing to the absence of evaporation ; 
whereas the water in the other jar rose to 60°, but did not boil, evapora- 
tion taking place freely from the surface and thus cooling the water. 
Upon the loss of heat by evaporation Crawford, in 1781, made some 
interesting experiments upon frogs; he compared the rates of warming 
of a dead and a living frog by exposure to warm air and to warm water, 
and found that the temperature of the former rose more rapidly than 
that of the latter. 


In another experiment he found that, when the air was 25°, the skin of a 
living frog was 20°, the stomach 21°:4; when the water was 16°:1, the skin of 
a living frog was 16°:2, the stomach 19°:2. It is to be noted that when the 
frog was kept in water its nose was above the surface, so that it might breathe ; 
in this way heat might be lost by evaporation from the lungs. Crawford, 
however, concluded from his experiments that the cooling was not solely due 
to evaporation, and that animals had the power of ‘ producing cold.” 

In 1810, Delaroche? published some instructive experiments, similar to 
those of Blagden, to show the effect of evaporation. He placed an alcarraza * 
full of water at 35°, and a rabbit whose temperature was 39°:7, in a stove 
heated to 45°; the temperature of the rabbit gradually rose to 43°:8, while 
that of the alcarraza fell to 31°:4, and remained stationary. In the second 
experiment he placed a frog and two pieces of moist sponge in a stove heated 
to 36°°5, and found at the end of an hour that the frog’s temperature was 
stationary at 28°:2, and that of the pieces of sponge at 27°°9 and 27°°6. 
Delaroche contests the results of Crawford’s experiments on frogs, and main- 
tains that these animals quickly take the temperature of the water in which 
they are placed, and that in this respect there is no difference between a dead 
and a living frog. 


According to the calculations of Vierordt and Ludwig, from 10 to 20 
5D 3 : : 
per cent. of the total daily loss of heat in an adult man is due to 
evaporation from the skin and respiratory tract. Further details on the 
discharge of water from the skin and lungs are given in another part of 
this work. The following values for the discharge of moisture from 
. 5 . i 
various parts of the human skin were observed by Waller :°— 


Palm of hand . 24 merms. per 20 sq. cm. (per 10 minutes) 

Sole of foot . 14 9 ” 

Forehead : 12 7 ” 

Cheek . . 6 ” ” panes: 
Axilla . 10 ” ” na 2s 
Popliteal space 10 9 ” eee 
Forearm . 5 » ” 

Leg . . 9) ” ” 


The influence of the size of the body upon the regulation of tem- 
perature.—The importance of the relation between the surface of the 
body and its mass, in respect to the loss and production of heat, was first 
pointed out by Bergmann.® The bigger an animal the greater the ratio of 


1 Crawford, Phil. Trans., London, 1781, vol. Ixxi. p. 485. 

2 Delaroche, Jowrn. de phys., Paris, 1810, tome Ixxi. pp. 294-296. 

3 A porous jar used for keeping water cool in hot climates. See also Edwards, ‘‘ De 
l’influence des agens physiques sur la vie,” p. 84. 

4 **Chemistry of Respiration,” this Text-book, vol. i. p. 711. 

5 ** Proce. Physiol. Soc.,” Journ. Physiol., Cambridge and London, 1894, vol. xv. For 
further observations see Hale White, Croonian Lectures, Lancet, London, 1897, June 19 
and 26, and Brit. Med. Journ., London, 1897, vol. i. p. 1654 et seg. 

6 «*Gottinger Studien,” 1847, Abth. 1, S. 595. 


REGULATION OF TEMPERATURE. 853 


its volume or weight to its surface, fur weight or volume increases as the 
cube, surface increases as the square. Thus, if the dimensions of a body 
be increased from 1 to 2, the surface increases from 1 to 4, and the cubic 
content from 1 to 8. A small animal, therefore, has a far greater 
surface in relation to its weight than a large animal, and if it is to 
maintain its temperature at a similar height, it must have either special 
means for preventing an excessive loss of heat or a more rapid produc- 
tion of heat. Both of these means are employed, and so effective are 
they, that the temperature of the smallest mammals and birds is often 
higher than that of the biggest. A mouse has a thicker covering 
of hair, and, relatively to its weight, a greater production of heat, than a 
horse. Further, as remarked by Bergmann, the smaller animals need a 
relatively greater supply of food, 

The large animals living in the tropics, such as the elephant and 
hippopotamus, are often remarkable for the small amount of hair upon the 
body and for their love of bathing, whereby the loss of heat is favoured. 
The largest mammals, the whales, are able by means of their enormous 
size and special layers of fat to resist the cold of the Arctic seas, and 
maintain a temperature equal to that of mammals living in the tropics. 
Water-fowl, especially those which inhabit cold regions, are noted for 
the protection afforded against cold by their down and feathers. 

These indications from the natural history of animals are fully con- 
firmed by experimental observations. The determinations made by 
Letellier and by Regnault and Reiset,? show that the intake of oxygen 
and the output of carbon dioxide are relatively greater in small than in 
large animals*; starvation is more rapidly fatal to small than to large 
animals, for during life they consume a relatively larger quantity of 
proteid.® Further, Rubner ® has determined the heat production of dogs 
of different size, and finds that the smaller animals produce relatively 
more heat in proportion to their weight than the larger animals, and that 
the heat production is proportional to the surface of the body. The 
following table gives some of these results :— 


Heat Production per | Heat Production per 


| 
=a. pare Surface per Kilo. - = 
Weight. | Surface. 7 Kilo. per Day. Square Metre of 
| Weight. Air=15°. ; Surface. 
| 
Kilo. } Sq. Cm. Sq. Cin. Kilo-cal. Kilo-cal. 
31°2 | 10,750 344 35°68 1036 
18°2 7662 421 46°20 1097 
9°6 5286 | 550 65°16 1183 
6°5 3724 573 66°07 1153 
3°19 2423 | 726 88:07 1212 


Similar results have been obtained by Langlois’ in the case of 
children. 


1 Ann. de chim. et phys., Paris, Sér. 3, tome xiii. p. 478. 

2 Thid., 1849, tome xxvi. p. 299 ; 1863, tome lxix. p. 129. 

5 See article ‘‘ Chemistry of Respiration,” this Text-book, vol. i. pp. 706-8. 
4 Chossat, ‘‘ Recherches expérimentales sur linanition,’’ Paris, 1843. 

> Voit, Hermann’s ‘‘ Handbuch,” Bd. vi. S. 88. 

6 Ztsehr. f. Biol., Miinchen, 1883, Bd. xix. 8. 535. 

” Centraibl. f. Physiol., Leipzig u. Wien, 1887, S. 237. 


854 ANIMAL HEAT. 


Rubner calculates that the tissues of a rat produce five and one- 
third times, the tissues of a sparrow thirteen times, as much heat as the 
same weight of tissue in a man. 


THE INFLUENCE OF THE NERVOUS SYSTEM UPON THE 
REGULATION OF TEMPERATURE. 


The nervous system exercises a control on both of the factors 
concerned in the regulation of temperature; upon the loss of heat 
by means of the vasomotor system, which regulates the amount of 
blood in the deep and superficial parts of the body, and by the respira- 
tory centre which controls the frequency and depth of respiration ; upon 
the production of heat through the nerves which control the activity 
of the tissues, chiefly the muscles. The control is of the nature of 
a reflex, and the sensory nerves of the skin and muscles are probably 
the most usual lines of the afferent impulses. The most important 
nervous centres are the vasomotor and the respiratory, but in addition 
to these and the so-called “motor” centres some physiologists maintain 
that special “ heat centres” exist in the brain. 

Vasomotor control of temperature.—The blood distributed to the 
body comes from the heart, where the temperature is, with the excep- 
tion of the liver and a few other internal parts, the highest in the body ; 
this warm blood is carried to the extremities and the surface of the 
body, where the temperature is lower. Now, three zones may, as 
Rosenthal? has pointed out, be recognised—an internal warm zone, an 
intermediate temperate zone, and an external cool zone; the first is 
represented by the deep organs and tissues, the second by the more 
superficial parts, and the third by the skin and subcutaneous tissue. 
Under ordinary circumstances the temperature will decrease from 
within outwards, for the most important seats of chemical change and 
heat production are situated within the first two zones, and the loss of 
heat is greatest from the surface of the skin. The blood circulating in 
the vessels distributes the warm blood of the interior to the superficial 
parts, and carries back cooler blood from the surface to the interior. 
The difference, therefore, in temperature between the interior and the 
surface will depend upon the rapidity and the quantity of the blood 
circulating through the different zones of the body; this distribution is 
regulated by the central nervous system through the vaso-constrictor 
and vaso-dilator nerves. The vasomotor nerves have their centre in 
the medulla oblongata, and probably subordinate ones in the spinal cord ; 
the distribution, however, of these centres and nerves is discussed else- 
where; here they will be considered merely as part of the nervous 
mechanism which regulates temperature. 

When the cutaneous and subcutaneous vessels are constricted, the 
quantity of blood distributed to the skin is diminished, the difference 
between the temperature of the surface of the body and its surroundings : 
is less, and consequently less heat is lost. This condition is brought 
about by external cold, and thus the heat of the body is economised and - 
its normal temperature is maintained, or may, under certain circum- 
stances, be raised, for it has already been shown that the first effect of a . 
cold bath is to raise the temperature in the axilla and rectum. On the | 
other hand, exposure to warmth causes a dilatation of the cutaneous » 

1 Hermann’s ‘‘Handbuch,” 1882, Bd. iv. Th. 2, S. 381. 


VASOMOTOR CONTROL OF TEMPERATURE. 855 


vessels, the difference between the temperature of the skin and its 
surroundings is increased, and likewise the loss of heat. Thus the first 
effect of a warm bath may be a fall in the temperature of the internal 
parts. The loss of heat by this flushing of the skin with hot blood and 
by sweating may be very great, as shown by the rapid fall in tempera- 
ture during the sweating state of ague or the crisis of pneumonia. 

These changes in the calibre of the vessels can be brought about 
reflexly, not only by sensations of heat and cold but by those of pain ; 
further, emotions can effect these changes, as in the blushing of excite- 
ment or shame, and the pallor of fright or anger; in fact, emotions may 
in different individuals have opposite effects upon the vascularity of the 
skin. 

An impression conveyed by the sensory nerves of one part of the 
body can influence the calibre of the vessels, not only on the same side 
but also on the opposite side. Thus, Brown-Séquard and Tholozan,’ found 
that plunging one hand in warm water raised the temperature of the 
opposite hand also. Waller,? however, has failed to confirm this. 

The explanation of the part played by the vasomotor nerves in 
the regulation of temperature is not so simple as may appear from a 
first consideration, for the problem is complicated by the fact that 
an increase or decrease in the vascularity of the skin is accom- 
panied by a similar change in the production of sweat; further, it is 
possible that the alterations in vascularity may affect the metabolism 
of the tissues. Upon this latter point there has been considerable dis- 
cussion. The first and most important experiment in this connection 
is that of Bernard,? who found that section of the cervical sympathetic 
caused a dilatation of the blood vessels and a rise of temperature in the 
ear of the same side. The enlargement of the blood vessels results in a 
greater and more rapid flow of blood through the ear, and this would 
naturally raise the temperature of the part. Bernard, however, did not 
look upon this explanation as complete: he held that the nervous 
system regulated not only the circulation but also the production of 
heat in the tissues, for he states, among other arguments, that section of 
the cervical sympathetic, after previous ligature of the veins of the ear, 
still caused a rise of temperature. According to Bernard, the nerve was 
both vaso-constrictor and frigorific. It was to be expected, however, 
that this view would be contested, for although a certain amount of 
heat would be produced in the ear, as in the metabolism of all tissues, 
yet that amount would be small, for the cartilage and other tissues of 
the ear are not the seats of an active exchange of material. 

Numerous experimenters * have decided against Bernard’s theory, and 
have attributed the changes in the temperature of the ear to alterations 

1 Journ. de Vanat. et physiol. etc., Paris, 1858, tome i. p. 497. 

2 Note communicated to the writer. 

3 <*Tecons sur la physiologie et la pathologie du systeme nerveux,” 1858, tome it, 
p. 490 ; ‘‘ Lecons sur la chaleur animale,” 1876, p. 297. 

4 Brown-Séquard, Med. Exam., Philadelphia, 1852, p. 489, and 1853, p. 9; Budgé, 
Compt. rend. Acad. d. sc., Paris, tome xxvi. p. 337; Ztschr. v. d. Verein f. Heilk. in 
Preussen, 1853, Bd. xxii. S. 149; Waller, Compt. rend. Acad. d. sc., Paris, 1854, 
tome xxxvi. p. 378; De Ruyter, ‘‘De actione atrope belladonne,” Diss., 1853 ; Schiff, 

-**Untersuch. z. Physiol. des Nervensystems,” 1855, Bd.i. S. 124 ; Allg. Wien. med. Ztg., 
1859, S. 318; Kussmaul and Tenner, Untersuch. z. Naturl. d. Mensch. u. d. Thiere, 
1855, Bd. i. S. 92; Callenfels, Zischr. f. rat. Med., 1858, Bd. vii. S. 157; Jacobson and 
Landre, Nederl. Tijdschr. v. Geneesk., Amsterdam, Bd. i. Heft 3 ; Donders, Wiinderlich’s 


‘Medical Thermometry,” p. 148; Bayliss and Hill, Journ. Physiol., Cambridge and London, 
1894, vol. xvi. p. 351. 


856 ANIMAL HEAT. 


in the blood supply alone. The difference in the temperature of the 
two ears, after section of the cervical sympathetic on one side, may be 
even as great as 12° or 16°, but it is proportionate to the difference in 
the quantity of blood (Schiff). If the two subclavians and the carotid 
on the same side as the divided sympathetic are ligatured, the tempera- 
ture of the ear falls below the normal, owing to the want of collateral 
circulation ; on the other hand, the temperature of the ear can be raised 
by ligature of the subclavians without section of the sympathetic nerve ; 
-this is due to the increased pressure of blood in the carotid artery 
-(Kussmaul and Tenner). The ears of a rabbit are to be looked upon as 
‘part of the mechanism for regulating temperature by the varying 
quantity of blood exposed; section of one sympathetic causes a fall in 
the temperature of the ear of the opposite side (Jacobson and Landre). 

In addition to the vasomotor nerves of the skin, it is important to 
remember that the vasomotor nerves to the respiratory tract and lungs 
may play an important but subordinate part in the regulation of the 
loss of heat.!. The importance of this method of regulation without doubt 
varies in different animals, and is greater in those with a thick coat of 
fur, as in the dog, who, when he is too hot, pants with open mouth and 
lolling tongue. This rapid respiration, 150-200 per minute in heated 
dogs, has been specially studied by Ackermann,” Goldstein, and Riegel ; # 
more recently, Richet ® has shown that a dog gives off from its respiratory 
tract, every hour, about 1 grm. of water for every kilo. of its body 
weight, when the external temperature is moderate, but when exposed 
to a hot sun it discharges ten times as much moisture and increases its 
respirations from 28 to 230 per minute. Any cause which prevents a 
dog from breathing rapidly and freely, such as a tight muzzle, causes a 
rise of two or three degrees in the animal’s temperature. 

The temperature of the body after damage or section of the 
spinal cord.—An examination of the numerous observations made upon 
the influence of injury or section of the spinal cord shows at first sight 
much confusion and apparent contradiction in the results. In the 
majority of cases, however, the results can be harmonised by taking into 
account the numerous factors of secondary import. In the first place, 
the experiments are only strictly comparable when they are performed 
upon similar animals under similar conditions. Thus the effect will vary 
according to the level of the injury or section of the spinal cord; a 
section high up in the cord will involve a more extensive paralysis than 
one low down, and the more extensive the paralysis the smaller the 
production, and the greater the loss of heat, owing to the dilated cutane- 
ous vessels. A section above the splanchnic area will obviously have a 
greater effect than one below that area; a section high up in the cord 
will interfere with the movements of respiration, whereas one low down 
will have comparatively little effect. Again, an animal with only the 
lower extremities and part of the trunk paralysed, may be able to main- 
tain its temperature by greater variations in the production and loss of 
heat in the parts still under control. The size of the animal is import- 
ant, for the bigger the animal the smaller is its surface in relation to its 

1 Bradford and Dean, Journ. Physiol., Cambridge and London, 1894, vol. xvi. p. 34. 
Here an account of previous work on the subject will be found. 

2 Deutsches Arch. f. klin. Med., Leipzig, Bd. ii. S. 361. 

3 Inaug. Abhandlung, Verhandl. d. phis.-med. Gesellsch. in Wiirzburg, 1871, S. 156. 

* Virchow’s Archiv, 1874, Bd. 1xi. S. 396. 

> Compt. rend. Soc. de biol., Paris, 1887, p. 482. 


NERVOUS CONTROL OF TEMPERATURE. 857 


mass, and thus the loss of heat due to vasomotor paralysis is less serious 
than in a small animal. Animals also differ in their method of 
regulation ; some, as in the case of man, have a well-developed vaso- 
motor system for the cutaneous surface, which is so slightly protected by 
natural covering: others, as in the case of dogs, have a thick fur, and 
regulate their temperature chiefly by variations in the production of 
heat and in the loss of heat from the respiratory tract. The distribu- 
tion and part played by the sweat glands varies greatly, as shown by a 
comparison of men and horses with dogs and cats. It is to be noticed 
further, in this respect, that marked differences exist even in individuals 
of the same race and variety; thus, some men and horses sweat much 
more readily and profusely than others. 

In addition to the above factors, it is necessary to consider the 
external conditions under which the injured animal finds itself. The 
external temperature greatly modifies the part played by the loss of heat 
from the paralysed parts. Most animals adopt a different posture, 
according to their need of heat or cold; thus a heated dog, rabbit, or 
mouse lies with extended trunk and limbs, whereas the same animal 
when it is cold, coils or huddles itself together. It is almost unneces- 
sary to point out that a paralysed animal could not assume these 
instinctive postures. A normal rabbit tied down in an extended position 
loses an abnormal quantity of heat, and its temperature falls, and in 
some cases the body is so greatly cooled that death results.* 

The above facts must therefore be borne in mind during any ex- 
amination of the effects of section or injury of the spinal cord. 

Attention was first drawn to the influence of the nervous system upon 
temperature, by the experiments and clinical observations of Benjamin 
Brodie He found that, after the head of an animal was cut off, or the 
cord divided high up in the cervical region, the circulation of the blood 
still continued when artificial respiration was performed, but the tem- 
perature fell even more quickly than in a dead animal. This Brodie 
correctly attributed to the great loss of heat from the circulating blood, for 
if the circulation was stopped by ligature of the heart, the fall of tem- 
perature was much retarded. It was also found that woorara (curari) and 
essential oil of almonds, by suspending the action of the central nervous 
system, also caused a fall in temperature. Brodie further compared the 
discharge of carbon dioxide by normal rabbits with that of rabbits with 
the brain removed or poisoned by woorara or the essential oil of almonds ; 
he states that the same quantity of carbon dioxide is formed in each of 
these cases, and therefore that the heat production is not due to chemical 
change but to nervous action. This conclusion is not warranted by the 
results of the determinations of the respiratory exchange, and the 
results themselves are not comparable, for, even when it was possible, the 
experiments were not made upon the same animals. 

The work of Brodie led to numerous experiments and discussions on 
this subject by Chossat,? Hale,t Legallois,? Wilson Philip,? Hastings,’ 

1 Legallois, Ann. de chim. et phys., Paris, 1817, Sér. 2, tome iv. p. 21. 

2 Phil. Trans., London, 1811, vol. ci. p. 36; 1812, vol. cii. p. 378 ; Med.-Chir. Trans., 
London, 1837, vol. xx. p. 146. 

3 Deutsches Arch. f. d. Physiol., Halle, 1822, Bd. vii. S. 282. 

4 London Med. and Phys. Journ., vol. xxii. 

5 Ann. de chim. et phys., Paris, 1817, Sér. 2, tome iv. 

6 ‘Experimental Inquiry into the Laws of the Vital Functions,” London, 1818, 2nd 


edition, p. 197 et seq. 
7 Quart. Journ. Se. Lit. and Arts, London, 1823, vol. xiv. p. 96. 


858 ANIMAL HEAT. 


and C. J. B. Williams.! The results on some points confirmed, on others 
contradicted, Brodie’s conclusions. Wilson Philip found that artificial 
respiration caused a fall in the temperature of intact animals, and that a 
slow ventilation prevented the temperature of the brainless animal 
from falling as quickly as that of a dead animal. Hastings obtained 
similar results, and Williams confirmed the observations of Wilson 
Philip, that the temperature of a brainless animal might even be shghtly 
raised by artificial respiration. Legallois carried out a very complete 
series of experiments upon the subject, and came to the followimg con- 
clusions: that a brainless animal upon which artificial respiration was 
performed suffered a reduction of temperature, but it was from one to 
three degrees less than in a dead animal; that im cooling through a 
certain number of degrees it parted with more heat than a dead animal : 
that inflation of the lungs of normal animals lowered their temperature,” 
and if the ventilation were continued for a long time they might die of 
cold; and, finally, that a fall in temperature might be produced by any 
condition which constrained or impeded the respiration. 

Tscheschichin* found that section of the spinal cord between the 
third and fourth cervical vertebrae caused the temperature of a rabbit to 
fall from 38°-9 to 32°-1. This he attributed to the increased loss of heat 
from the paralysed cutaneous vessels, and to diminished production of 
heat ; the higher the section, the more extensive the paralysis of the blood 
vessels, and the greater the loss of heat; stimulation of the peripheral 
end of the cord caused contraction of the blood vessels, and the loss of 
heat was less. 

In rabbits, section of the spinal cord at the commencement of the 
dorsal region caused the rectal temperature to fall from 40° to 24° in 
five hours (Bernard).* In guinea-pigs, section of the upper dorsal region 
produced a progressive fall in the rectal temperature from 38°9 to 16° 
in twenty-four hours, when the animal died (Pochoy).° 

Fischer ® found a rise of 0°°5 to 1°-7 in the temperature of dogs and 
rabbits after complete section of the cervical portion of the spinal cord, 
but no rise when the operation was performed in the dorsal or lumbar 
regions. He concluded that an inhibitory centre for heat existed in 
the cervical region of the cord, A series of experiments were made by 
Naunyn and Quincke " upon the effect of crushing the spinal cord. 
They selected dogs of large size, and with thick fur, in order to diminish 
the importance of the loss of heat. They found that, after the cord was 
crushed at the level of the sixth cervical vertebra, the rectal tempera- 
ture fell, unless the excessive loss of heat due to vasomotor paralysis was 
prevented by a fairly high external temperature ; if the air was warm, the 
temperature rose two or three degrees, and even higher after death. 
These observers concluded that there were nerve fibres which, passing 
from the brain to the spinal cord, inhibited the production of heat *; and 
that, after section, the production as well as the loss of heat were 


1 «Observations on the Changes produced in the Blood in the course of its Circulation,” 
London, 1835. 

2 See also Fawcett and Hale White, Jowrn. Physiol., Cambridge and London, 1897, 
vol. xxi. p. 435. 

3 Arch. f. Anat., Physiol. wu. wissensch. Med., 1866, S. 151. 

4 “*Tecons sur la chaleur animale,” 1876, p. 161. 

© These, Paris, 1870. 

§ Centralbl. f. d. med. Wissensch., Berlin, 1869, No. 17. 

7 Arch. f. Anat., Physiol. w. wissensch. Med., 1869, 8. 174, 521. 

8 See also Ott and Collmar, Journ. Nerv. and Ment. Dis., N.Y., 1887, p. 428. 


NERVOUS CONTROL OF TEMPERATURE. 859 


increased, and if the augmentation of the latter was not excessive, the 
temperature of the body rose. On the other hand, Riegel found that 
the production of heat was diminished, and he explains the rise of 
temperature in Naunyn and Quincke’s cases as due to absence of the 
rapid breathing whereby normal dogs regulate their temperature. 
Further, Schroff? found a rise in the temperature of dogs when they 
were kept in a warm chamber after opening of the spinal canal, without 
damage to the spinal cord. 

Rosenthal* repeated Naunyn and Quincke’s experiments, but never 
found any rise of temperature, unless the animals were kept in a 
chamber warmed to 32°. If the section was made lower down in the 
cord, more muscles remained under the control of the animal, and by 
the contraction of these muscles more heat was produced, and the 
temperature raised when the external air was warm. Rosenthal further 
points out that it is probable that septic fever was the cause of the rise 
of temperature in some of Naunyn and Quincke’s dogs. 

Pfliiger’s * experiments upon the respiratory exchange of rabbits, after 
section of the spinal cord in the lower cervical region, show that such 
an animal is comparable to a cold-blooded animal; a rise in external 
temperature increases, a fall diminishes, the metabolism and the 
temperature of the animal. The same result is even more markedly 
shown in the case of a smaller animal. Thus the following figures 
show the effect of sudden changes in the external temperature upon the 
output of carbon dioxide of a mouse before and after section of the spinal 
cord in the lower cervical region :*°— 


BEFORE SECTION OF CoRD. CONSECUTIVE THREE HouRS AFTER SECTION OF CorD. CON- 
PERIODS OF 15 MINUTES. SECUTIVE PERIODS OF 15 MINUTES. 
CO, in Tempera- | | Co, in Tempera- 
Decimilli- tureof | Remarks. | Decimilli- ture of | Remarks. 
grammes. | Water Bath. grammes. | Water Bath. 
391 | 25°°0 Mouse very quiet. | 222 | 22°°0 | Mouse quiet. 
feear2 =| aar-0 Fegdi ad byl 229 | -22°0 * be 
558 12esh Mouse active. | 250 ula Cees Mouse moves its fore- | 
limbs very actively. | 
572 12°°5 we | 158 | 11°75 | Mouse quiet. 
| | 


We may conclude, therefore, that in animals the general effect of 
section of the spinal cord in the lower cervical region is a fall in the 
temperature of the body, due to a reduction in the metabolism of the 
paralysed muscles, and to excessive loss of heat consequent upon the 
vasomotor paralysis. The exceptional cases appear to be due to a high 
external temperature, and to interference with the rate of respiration, 
which in dogs plays an important part in the cooling of the body. 


1 Arch. f. d. ges. Physiol., Bonn, 1872, Bd. v. S. 629. 

2 Sitzungsb. d. k. Akad. d. Wissensch. Math.-naturw. Cl., Wien, Bd. Ixxiii. Abth. 3, 
S. 141. 

3 Zur Kenntniss d. Warmeregulierung bei den warmbliitigen Thieren,” 8. 35; Hermann’s 
‘‘ Handbuch,” Bd. iv. Th. 2, S. 437. 

4 Arch. f. d. ges. Physiol., Bonn, 1878, Bd. xviii. S, 321. 

5 Pembrey, ‘‘Proc. Physiol. Soc.,” Journ. Physiol., Cambridge and London, 1894- 
1895, vol. xvii. 


860 


ANIMAL HEAT. 


An examination of the cases of crushed spinal cord in man shows 
discordant results, in some cases a marked rise, in others a fall in the 


temperature of the body. 


some of the cases recorded :— 


The following table gives the chief data in 


Sex and 
Age. 


Seat of Injury. 


Temperature. 


Remarks. 


Observer. 


M. 


M., 53. 


M., 36. 


Crush at level 
of fifth and 
sixth cervi- 
cal verte- 
bre. 


Crush at level 
of fifth and 
sixth cervi- 
cal verte- 
bre. 


Crush at level 
of fifth cer- 
vical verte- 
bra. 


Crush at level 
of seventh 
cervical ver- 
tebra, 


Crush at level 
of fifth cer- 
vical verte- 
bra. 


43°-9 (111° F.), be- 
tween scrotum and 
thigh. 


35° (95° F.), rectal. 


35° (95° F.), rectal 
and axillary just 
before death. 


Below 35° (95°), 4 
P.M., first day. 


Below 35° (95°), 6.30 
P.M., first day. 


Below 35° (95°),11.30 
p.M., first day. 
36°°8 (98°°2), morn- 
ing, second day. 


| 36°°9 (98°:4), even- 


ing, second day. 
38°°9 (102°), after- 
noon, third day. 


36°°9 (98°°4), sixth 
hour after acci- 
dent. 


38°°6 (101°°5), third 
day. 

38°:0 (100°°4), fourth 
day. 

39°°0 (102°-2), fifth 
day. 

37°°45 (99°°4), sixth 
day. 

40°°0 (104°°0), first 
day, axilla. 


40°°3(104°°5), second 


ay. 
38°°9 (102°°0), third 
day. 


Diaphragmatic breath- 
ing; respiration slow 
and irregular ; pulse 
weak; countenance 
livid ; death twenty- 
four hours after acci- 
dent. 


Paralysis extended to 1 
in. above nipple line ; 
patient complained of 
feeling cold. : 

Death on fifth day ; no 
injury to other parts 
of body. 


Complete paralysis of 
all limbs ; diaphrag- 
matic breathing; skin 
cold and dry; pulse 
72, 

Skin cold and clammy ; 
patient complains of 
feeling cold. 

Pulse 50. 


Skin warm and dry; 
pulse 64. 
Skin hot and dry. 


Death. 


Diaphragmatic breath- 
ing ; imperfect paraly- 
sis of arms; patient 
felt very cold. 

Skin of natural warmth ; 
pulse 72. 


Pulse 99. 


Face mottled; pulse 84; | 


death. 


Slight power of moving 
shoulders and upper 
arms; skin flushed 
and very hot. 

Pulse 96, regular, quiet. 


[Continued on next page. 


1 Med. Chir.-Trans., London, 1837, p. 146. 
2 Lancet, London, 1875, vol. i. pp. 713, 747. 
® Quoted from Hutchinson, Joc. cit. 


Brodie. ! 


Hutchinson.? 


Churchill.? 


NERVOUS CONTROL OF TEMPERATURE. 861 


rae | Seat of Injury. Temperature. Remarks. Observer. 
| | 
M.— —_ Crush at level | 41°-1 (106°), fourth | 40°-2 (104°°4) on foot ; | Churchill.’ 
| contd.| of fifth cer- day. patient died soon after 
| vical verte- | inaviolent spasm, and 
bra. | a quarter of an hour | 


after death, tempera- 
ture in axilla=43°°3 


(110°). 
| M.,-48. | Crush at level | 33°°5 (92°°3), on ad- | Temperature, taken in | Wagstaffe.! 
| of sixth cer- mission to hos- both rectum and ax- 
| vical verte-| pital. | illa, fell steadily until 
| bra; frac- death. 


| tureofskull. | 27°°6 (81°°7), forty- | Death. 
eight hours later. | 


M., 22. | Crush between | 


33°°9 (93°-0), on ad- | Patient drowsy and pro- | Le Gros Clarke.? | 


sixth and) mission. strate. 
| seventh cer- | 27°°8 (82°°0), a few | Death about forty-eight 
| vical verte- hours beforedeath. | hours after accident. 
| bre. 
M., 39. | Crush at level | 34°°5 (94°°1), four; —...... | Billroth.? 


of fourth hours after the) 
; and fifth; accident. 

cervical ver- | 86°°5 (97°°7), eighth| —...... 
tebree. hour. 
ANP 26) a(HOGTO)S VIRION) aude 
A.M., second day. | 


Death at 2.5 p.M. on sec- 
ond day ; post-mortem 
rise to 42°°9 (109°:2) 
in ten minutes. 


42°°4 (108°°3),1P.M., 
second day. 


| 


M., 34. | Crush at level | 87°°6 (99°-7), five Complete paralysis of | Frerichs.? 
| of fifth and hours after acci-| trunk and limbs; dia- | 


sixth cervi-| dent. | phragmatic breathing. | 
cal verte- | 40°°9(105°°6), twelfth; = = —...... 
brie. / hour. 


| 42°71 (07838); ete Gil ie) des.222 
teenth hour. 
45-6 (V10'-D) sate oe eee 
teenth hour, | 
eleventh minute. | | 
43°-2 (109°:7), nine- | Death. 

| teenth hour, |} 
thirty-fifth min- 

ute. 

| | | 


These discordant results have to be explained. It is worse than useless to 
say that the effects are due to the removal of the regulating influence of 
“heat centres” in the brain, centres whose very existence is problematical. 
Observations upon the deep and surface temperature, and upon the amount 
of moisture given off by the skin, are needed to show whether the changes in 
temperature are due to disturbance in the production or in the loss of heat, 
or more probably in both. The data upon these points are insufficient, but, 
recently, such observations have been made by Pembrey,* in the case of two 


1 Quoted from Hutchinson, Zoe. cit. 

2 Arch. f. klin. Chir., Berlin, 1868, Bd. ix. S. 161. 

3 Recorded by Lorain, ‘‘ De la temperature du corps humain,” tome i. p. 500. 

4«*Proe, Physiol. Soc.,” Journ. Physiol.. Cambridge and London, 1897, vol. xxi. ; 
Brit. Med. Journ., London, 1897, vol. li. p. 883. 


862 ANIMAL HEAT. 


patients suffering from traumatic section of the spinal cord. The general result 
is a subnormal temperature so long as the patient’s condition is not complicated 
by other internal or external disturbance. The subnormal temperatures are 
due to excessive loss and diminished production of heat, owing to the 
vasomotor and motor paralysis. The section of the spinal cord high up in the 
cervical region abolishes the power of regulating temperature. When the 
patient is exposed even to moderate cold, his temperature falls owing to the 
increased loss of heat and to the diminished production of heat. On the 
other hand, if the weather be hot and the patient be too well covered with 
bedclothes, his temperature rises, and may reach a dangerous height, owing to 
the diminished loss and the increased production of heat in the body. In the 
paralysed man the production of heat rises and falls with the external tempera- 
ture. In the case of the high temperatures there are several factors which 
may play an important part; the paralysed parts soon cease to sweat ; in fact, 
Horsley has shown that, by the use of pilocarpine, it is possible to localise 
the level of the injury to the cord. The respiration is hampered, it is only 
diaphragmatic ; the ventilation of the lungs is therefore imperfect, and less 
heat is lost by the cooling of the inspired air, and by the evaporation of 
water from the respiratory tract to saturate the expired air with moisture. 
Further, the warmer the paralysed tissues the greater is their metabolism and 
production of heat. 

It naturally follows that, in cases of section of the spinal cord in the 
dorsal or lumbar regions, the regulation of temperature is less disturbed. 


The influence of the brain upon the regulation of temperature. 
—It is impossible to state concisely and dogmatically the influence of 
the brain upon the temperature of the body. With our present know- 
ledge it is only permissible to review the chief results obtained by 
various observers, and to draw some provisional conclusions. 

In 1866, Tscheschichin? published the results of experiments, which 
showed that a section between the medulla oblongata and the pons 
Varolii caused a rise in the temperature of rabbits. In one case the 
rectal temperature rose in two hours from 59°4 to 42°6, and at the 
same time there was a corresponding increase in the rate of the pulse 
and respiration. On the other hand, section of the spinal cord between 
the third and fourth cervical vertebrz caused, in another rabbit, a fall 
in temperature from 38°9 to 32°1. From these experiments Tsches- 
chichin concluded that a moderator centre exists in the brain, and pre- 
vents the excessive activity of an augmentor heat centre in the medulla 
oblongata. Lewizky* repeated but could not confirm these experi- 
ments; he observed a steady fall in temperature after the operation. 
The subject was then taken up, under the guidance of Heidenhain, by 
Bruck and Giinther, who, working upon rabbits, obtained positive 
results in eleven, negative in twelve cases. They found in one case a 
rise from 39°31 to 42°°5 in the rectal temperature, two or three hours 
after the operation. These observers further found that simple puncture 
with a probe between the pons and medulla was more effectual than 
section, and they noticed that the rise in temperature occurred not only 
in the interior, but also in the peripheral parts of the body, a fact which 
indicates that the rise is due to increased production of heat. Bruck 
and Giinther do not agree with Tscheschichin’s view of a moderator 
centre, for they point out that the results can be produced by electrical 


1 Arch. f. Anat., Physiol. u. wissensch. Med., 1866, S. 151. 
2 Virchow’s Archiv, 1869, Bd. xlvii. S. 357. 
3 Arch. f. d. ges. Physiol., Bonn, 1870, Bd. iii. S. 578. 


INFLUENCE OF BRAIN ON HEAT REGULATION _— 363 


stimulation as well as by puncture of that portion of the nervous 
system, and are probably due to traumatic stimulation. It is to be 
noted that irregular muscular movements were observed in many of the 
cases. 

Schreiber,! from the results of experiments performed upon rabbits, 
came to the conclusion that a rise of temperature followed injury 
to all parts of the pons, to the pedunculi cerebri, cerebellum, and 
cerebrum, when the animal was protected by a covering of wool or 
flannel against excessive loss of heat; injury between the medulla 
oblongata and the pons always caused a rise in temperature. In most 
cases, however, the rise in temperature was very small, and the experi- 
ments were often complicated by spasms of the muscles. 

Observations upon the production of heat, as determined by a 
calorimeter, and also upon the animal’s temperature after lesions of 
various parts of the central nervous system, were made by Wood.’ 
Section of the spinal cord above the origin of the splanchnic nerves 
produced an increase in the loss but a decrease in the production of 
heat; on the other hand, section between the medulla oblongata and the 
pons caused an increase in both the production and loss of heat, and for 
this reason Wood supported the view of Tscheschichin, that a moderator 
centre exists In or above the pons. 

Eulenberg and Landois? found that in dogs destruction of a portion 
of the cortex of the brain in the neighbourhood of the sulcus cruciatus 
caused a rise of temperature, which was most marked on the side of 
the body opposite to the lesion: they looked upon this effect as due to 
vasomotor disturbance. These results were confirmed by Hitzig* and 
Wood, but on rabbits Kiissner® and H. Rosenthal® obtained negative 
results. 

Injury to the front of the brain was found by Richet’ to produce a 
rise of temperature, and Ott ® obtained a similar result by injury to the 
corpus striatum; this observation was confirmed by Girard,? Baginsky 
and Lehmann.!® In 1885, Aronsohn and Sachs" published the results 
of an important series of experiments upon rabbits; they found that 
puncture with a probe, the greatest thickness of which was 3 mm., 
had no effect upon the temperature of the body when the operation was 
performed upon the front part of the cerebral hemispheres, but a 
puncture passing through the median side of the corpus striatum near 
the nodus cursorius of Nothnagel caused, within a few hours, a rise of 
temperature which persisted for two or three days. The rise varied 
from 1°°7 to 2°-4, and could also be produced by electrical stimulation of 
the corpus striatum. Control experiments showed that the injury to 


1 Arch. f. d. ges. Physiol.,Bonn, 1874, Bd. viii. S. 576. 

2 <¢Fever, a Study in Morbid and Normal Physiology,” Smithson. Contrib. Knowl., 
Washington, 1880. 

3 Centralbl. f. d. med. Wissensch., Berlin, 1876, No. 15; Virchow’s Archiv, 1876, 
Bd. Ixviii. S. 245. 

4 Centralbl. f. d. med. Wissensch., Berlin, 1876, No. 18. 

5 Thid., 1877, No. 45. 

6 <¢ Binfluss des Grosshirns auf des Korperwarme,” Diss., Berlin, 1877. 

7 Compt. rend. Soc. de biol., Paris, 29th March 1884, p. 189 ; Compt. rend. Acad. d. sc., 
Paris, 31st March 1884; Arch. .de physiol. norm. et path., Paris, tome vi. 

8 Journ. Nerv. and Ment. Dis., N.Y., 1884, Nos. 7 and 8; 1887, p. 152; 1888, p. 551 ; 
Therap. Gaz., Detroit, 1887 ; Brain, London, 1889. 

9 Arch. de physiol. norm. et path., Paris, 1886, tome viii. 

10 Virchow’s Archiv, 1886, Bd. evi. S. 258. 

U Arch. f. d. ges. Physiol., Bonn, 1885, Bd. xxxvii. S. 232. 


864 ANIMAL HEAT. 


the cortex during the performance of the puncture did not cause any 
rise of temperature. The high internal temperature after puncture of 
the corpus striatum was accompanied by an increase in the temperature 
of the skin, and by an increase in the respiratory exchange, and in the 
discharge of nitrogen in the urine. The mean result of the determina- 
tions of the respiratory exchange was as follows :— 


OXYGEN. CARBON DIOXIDE. 
RECTAL TEMPERATURE. ee 
in c.c. at 0° C., 760 m.m. per Kilo. and Hour, 


Before puncture 38°°5 664°°0 626°°7 


After puncture 39°°8 749°°7 715°°8 


Aronsohn and Sachs conclude that the rise in temperature after the 
puncture is due to increased production of heat, and increased metabolism, 
arising from the stimulation of the corpus striatum. 

These experiments have been repeated and extended by Hale White, 
who found no rise in the temperature of rabbits after lesions of the 
white matter of the cerebrum, but an almost constant effect after injury 
of the corpus striatum and optic thalamus. In the case vf lesions of 
the corpus striatum, the rectal temperature rose to 41°6 in two cases, 
to 41°1 in eleven cases, and to 40° in eighteen; while in three cases 
there was a slight rise, and in two a fall in temperature. The average 
rise was 1°°7, and was attained within four to sixteen and a half hours 
after the operations, and persisted for about sixty-two hours. After 
lesions of the optic thalamus, the average rise of temperature was 1°-4, 
Hale White concludes that the corpus striatum and the optic thalamus 
can modify the temperature of the body, and that they do not work 
directly through the vasomotor system. No increase in the discharge of 
carbon dioxide was observed in rabbits after damage to the corpus 
striatum.? 

Several cases of a rise in temperature in man after a hemorrhage 
into the corpus striatum have been recorded.’ 

Recently Tangl* has observed the effect of puncture through the 
anterior part of the optic thalamus in horses. In one case the tempera- 
ture rose to 40°8 within twenty-four hours, in another to 40°4 within 
sixteen hours of the operation, and in two other cases there was no 
effect. The temperature remained only for a short time at the above 
height, and then fell. 

Fredericq® found that removal of the cerebral hemispheres in pigeons 
caused practically no difference in the daily curve of their rectal 
temperature. This observation has been confirmed by Corim and Van 
Beneden,® who have, in addition, shown that the pigeons without their 
cerebral hemispheres produce the same amount of carbon dioxide and heat 


1 Journ. Physiol., Cambridge and London, 1890, vol. xi. p. 1. 

2Hale White, Croonian Lectures, Lancet, London, 1894, July 10, and Brit. Med. Journ., 
London, 1897, vol. ii. p. 71. 

3 Bourneville, Ferrier, J. H. Bryant, Hale White; references given by Hale White, Brit. 
Med. Journ., London, 1894, 17th Noy. 

4 Arch. f. d. ges. Physiol., Bonn, 1895, Bd. lxi, 8. 559. 

5 Arch. de biol., Gand, 1882, tome iii. p. 747. 

6 Tbid., 1889, tome vii. p. 265. 


DEVELOPMENT OF HEAT REGULATION. 865 


as do normal pigeons. The rapid rise in temperature which occurs 
when a hibernating marmot awakes, is not prevented by removal of the 
cerebral hemispheres. 

An impartial examination of the above evidence leads to the verdict 
that the existence of the so-called “heat centres” in the brain has not 
been proved. In the first place, the results, even in the hands of the 
same experimenter, are inconsistent; some observers obtain exactly 
opposite effects from apparently similar lesions. Further, in many 
cases rabbits have been used for these experiments, and it is notorious 
that ‘their temperature is liable to considerable variations during 
operative procedures. Even if the existence of these centres be 
granted, even if it be allowed that after puncture there is an increase in 
metabolism and in the production of heat, it by no means follows that 
the centres are special centres for the regulation of temperature, and 
give off “thermic nerves.” 

It seems more probable that the mechanism of heat regulation 
has the same cerebral representation as the voluntary muscles. In 
the lower warm-blooded animals the representation of these in the 
cerebral cortex is not well developed, and it has likewise been shown 
that the removal of the cortex in them has little or no effect upon 
the regulation of temperature. 


THE DEVELOPMENT OF THE POWER OF MAINTAINING A CONSTANT 
TEMPERATURE. 


In the cold-blooded animals there are traces of the power of maintaining 
a constant temperature, as shown by the high temperature which a female 
python is able to maintain for many weeks when she is incubating her eggs. 
This instance is the more remarkable because during that time the python 
takes no food or exercise. Further instances have already been mentioned in 
the case of bees, and some species of fish. 

It is possible to trace in the warm-blooded animals the gradual develop- 
ment of this power of regulation. Thus, during the development of a chick 
there is first a stage in which the embryo responds to changes of temperature 
in a similar manner to that of a cold-blooded animal; then a stage of transition 
in which there is a regulation for moderate changes of temperature ; and 
finally, when a chick is hatched, the power of regulation resembles that of 
a warm-blooded animal.! In 1824, Edwards? pointed out that young 
mammals and birds may be divided into two classes, the warm-blooded 
and the cold-blooded, according as they are, or are not, able to maintain their 
temperature when removed from the warmth of the parents. The difference 
lies in the relative development of the two classes—active young animals 
covered with fur or feathers, as in the case of the guinea-pig and chick, belong 
to the former class; while young animals born naked, blind, and helpless, 
belong to the cold-blooded group. The inability to maintain a constant 
temperature is due to diminished production of heat on exposure, and only 
secondarily to excessive loss of heat. It has recently been shown that the 
chick and guinea-pig can at birth regulate their production of heat, that young 
cold-blooded mammals and birds are able to regulate only for moderate changes 
of external temperature ; for, when exposed to cold, their temperature and 


1 Pembrey, Gordon, and Warren, Journ. Physiol., Cambridge and London, 1894-95, 
vol, xvii. p. 331. 
2 «* De influence des agens physiques sur la vie,” 1824. 


VOL. I.—55 


866 ANIMAL HEAT. 


production of carbon dioxide fall, and they resemble cold-blooded animals. 
About the fifteenth day after birth, they respond to a fall in the temperature 
of their surroundings with increased muscular activity and output of carbon 
dioxide, and thus maintain their temperature (Pembrey !). 

In the lowest mammals the temperature is much lower than in the higher 
members of the group. Thus the temperature of the Echidna hystrix is 27°'5, 
and that of the Ornithorhynchus, 24°°8.* 

Further, a hibernating mammal is an instance of an animal at one time warm- 
blooded and at another time cold-blooded, and its power of regulation is in 
many respects similar to that of an immature mammal.’ Additional proofs 
of the gradual development of the power of maintaining a constant tempera- 
ture are found in the unstable temperature of infants and animals. In 
premature and weak infants the power is imperfect, and the temperature is 
below the normal.* - It is in man that the perfection of this power is reached ; 
he of all animals has the most constant temperature under extreme differences 
of external heat and cold. 

It is impossible with our present knowledge to state what are the 
structural differences which accompany the development of the power of 
regulation. This much we may say: the power appears to be associated 
chiefly with the control of the nervous system over the skeletal muscles and 
those of the blood vessels, An anesthetic, or curari, or section of the spinal 
cord reduces a warm-blooded animal to a cold-blooded condition ; its tempera- 
ture and production of carbon dioxide vary with, and in the same direction as, 
the temperature of its surroundings. In a hibernating animal the fall of 
temperature is accompanied by greatly diminished activity of the muscular 
and nervous systems; and the sudden rise in temperature, when the animal 
awakes from its torpidity, is marked by a sudden increase in the discharge 
of carbon dioxide and in muscular activity. Those young mammals and birds 
which are born with well-developed control over their muscular system, are 
able to regulate their temperature even at birth, whereas those born in a 
helpless condition do not attain this power until a week or two after birth, 
at a time when their power of co-ordination is much increased. 


THE TEMPERATURE OF THE Bopy AFTER DEATH. 


After death the temperature of the body generally falls, the loss of heat 
varying according to the difference between the temperature of the corpse 
and that of its surroundings; another important factor is the surface of the 
body in relation to its mass, for the corpse of an infant or of a wasted 
subject cools more rapidly than that of a well-developed adult.° In some 
cases, however, a rise of temperature is observed in the corpse, especially 
when death has resulted from tetanus, acute rheumatism, typhoid fever, small- 
pox, cholera, or injuries to the brain and spinal cord. A few of the cases 
recorded are given in the following table :— 


1 Journ. Physiol., Cambridge and London, 1895, vol. xviii. p. 363. 

? Mikloucho Maclay, Proc. Linn. Soc. New South Wales, 1883, vol. viii. p. 425 ; vol. ix. 
p- 1205 ; Semon, Arch. f. d. ges. Physiol., Bonn, 1894, Ba. lviii. S. 229. 

ogy ie and Hale White, Journ. Physiol., Cambridge and London, 1896, vol. xix. 

Alls 
aa Crombie, Indian Ann. Med. Sc., Calcutta, 1873, vol. xvi. p. 597; Raudnitz, Zétschr. 
Jf. Biol., Miinchen, 1888, Bd. xxiv. S. 423. 

° Taylor and Wilks, Guy’s Hosp. Rep., London, 1863, p. 184; observations on one 
hundred cases; Sutton, Brit. Med. Journ., London, 1874, vol. i. p. 153; Bidder and 
Schmidt, ‘‘ Die Verdiuungssafte und der Stoffwechsel,” S. 323 ; Womack, S¢. Barth. Hosp. 
Rep., London, 1887, vol. xxii. p. 193; Niderkorn, ‘‘ De la rigidité cadaverique chez 
Vhomme,” Paris, 1872. 


TEMPERATURE OF THE BODY AFTER DEATH. 867 


| | 
an | ae Disease. observation, | Observer. 
| 
45° Pyemia Left ventricle. | Davy.? 
(34 hrs. post-mortem) 
| 42°°2 | Sudden death, cause se a3 
(54 hrs. post-mortem) | undetermined. 
43°°75 Small-pox. Axilla. Simon.’ 
(1 hour post-mortem) | 
ea 4° 7”) ’ be) 39 
ceeaE 44°°5 Sunstroke. A Levick.* 
44°°75 45°°4 Tetanus. Wunderlich. 
(57 min. post-mortem) - 
sae 4°-2 Cholera. Rectum. | Mackenzie.? | 
42°°3 43°°2 Erysipelas. Axilla. | Eulenburg.® 
(15 min. post-mortem) 
40°4 42°°3 ” } re) ” 
(20 min. post-mortem) 
= 41°°8 Sunstroke. Thompson.’ | 
36°°1 38°°3 Apoplexy. AP De Haen.® 
(74 min. post-mortem) 
41°°6 43° Tetanus. ae Lehmann.? | 
(30 min. post-mortem) 
43°°01 44°°03 Pyzemia. | Rectum. Quincke and | 
(1 hour post-mortem) Brieger.° | 
42° 43°°4 Pneumonia 55 i 
(1 hour post-mortem) | delirium tremens.| 
41°*1 43°°3 Crush of | Axilla. Churchill. ? 
(15 min. post-mortem) | spinal cord. | 


The causes of this post-mortem rise in temperature have been investigated 
by various observers.!2 The most important factors are these. When the 
circulation and respiration cease at death, the normal loss of heat from these 
causes and from sweating also comes to an end, but the tissues live for a short 
time and produce heat even after the death of the organism as a whole. If 
this production of heat is greater than the loss of heat from the corpse, the 
temperature rises; if, on the other hand, it is less, then the effect is only to 
delay the fall of temperature. The next source of heat is in the muscles on 
the onset of rigidity ; and, finally, when decomposition sets in, and this may 
after some diseases occur exceedingly rapidly, there is a further production of 
heat due to putrefaction. In some cases the temperature of a corpse does not 
fall to that of the atmosphere even in four or five days. 


° Penn. Hosp. Rep., Philadelphia, 1868, vol. i. p. 369. 

+ Arch. d. Heilk., Leipzig, 1861, Bd. ii. 8. 547. 

° London Hosp. Rep., vol. ili. p. 454. 

° Centralbl. f. d. med. Wissensch., Berlin, 1866, No. 5. 

Brit. Med. Journ., London, 9th July 1870. 

8 Quoted from Valentin, Deutsches Arch. f. klin. Med., Leipzig, 1869, S. 201. 

® Schmidt's Jahrb., Leipzig, 1868, Bd. exxxix. 8. 241. 

10 Deutsches Arch. f. klin. Med., Leipzig, 1879, Bd. xxiv. 8S. 284. 

1 Churchill, quoted from Hutchinson, Lancet, London, 1875, vol. i. p. 713. 

12 Besides those above enumerated, the following may be mentioned :—Seume, Thesis, 
Leipzig, 1856 ; Erb, Deutsches Arch. f. klin. Med., Leipzig, 1865 ; Thomas, Arch. d. Heilk., 
Leipzig, 1868, Bd. ix. S. 17, 31; Goodhart, Brit. Med. Journ., London, 1874, vol. i. 
p- 303; Huppert, Arch. d. Heilk., Leipzig, 1867, Bd. viii. S. 321; Fick and Dybkowsky 
Vriljschr. d. naturf. Gesellsch. in Zurich, 1867 ; Schiffer, Centralbl. f. d. med. Wissensch. 
Berlin, 1867, S. 849; Arch. f. Anat., Physiol. wu. wissensch. Med., 1868, S. 442. 

13'The author is indebted to Drs. Haldane, Hale, White, and Waller for valuable 
suggestions on various points, dealt with both in this and in the preceding article. 


METABOLISM. 


By E. A. SCHAFER. 


ConTENts :—Introductory, p. 868—Balance of Nutrition, p. 871—Composition of 
Foodstuffs, p. 872—Heat Value of Foodstuffs, p. 874—Necessary Amount of 
Proteid, p. 875—Special Constituents of Diet, and their Effect on Metabolism, 
p. 878—Gelatin, p. 878—Carbohydrates, p. 880—Fats, p. 881—Inorganic Sub- 
stances, p. 882—Metabolism in Inanition, p. 887—With purely Proteid Diet, 
p. 891—Relative Metabolic Activity of Tissues, p. 895—Nitrogenous Meta- 
bolism, p. 896—Influence of the Liver on Proteid Metabolism, p. 900—Influence 
of Muscular Activity on Proteid Metabolism, p. 911—Metabolism of Carbo- 
hydrates, p. 916—Glycogen formation, p. 919—Phloridzin Diabetes, p. 920— 
Glycogenesis, p. 922—Puncture Diabetes, p. 926—Action of Pancreas on 
Carbohydrate Metabolism, p. 927—Metabolism of Fat, p. 930—Source and 
Formation of Fat, p. 931—Action of Liver on Metabolism of Fat, p. 935. 


Introductory.—The word “metabolism” has come into use in this 
country as the equivalent of the German word Stoffwechsel, which 
strictly means “exchange of material.” The subject which it denotes 
embraces all that is known or conjectured regarding the changes which 
occur within the body in the materials of the food, or foodstuffs, and 
in the materials which compose the tissues and organs of the body 
itself, or bodystuffs. Generally, however, the digestive changes in the 
food are excluded from the scope of the expression. There is no special 
reason, other than that of convenience of description, why this should be 
the case, for the digestive changes in the food must, like all other 
chemical changes occurring within the body, influence the general con- 
ditions of the economy. The usual course will, however, be followed 
in this article, and I shall confine what I have to say to the changes that 
occur after the food is absorbed, in so far as they have not been already 
treated of in the articles in this work dealing with the chemistry of the 
urine and with the chemical processes of respiration and heat production, 
both of which subjects constitute essential parts of the whole subject 
of metabolism. 

The metabolic changes which are undergone by the tissues must be 
of two kinds, which are opposite in nature. For, on the one hand, the 
complex molecules which constitute living tissue or bioplasm,? are built 


1 Hering, ‘* Vorgiinge der lebenden Materie,” Prag, 1888. A translation, by Miss F. A. 
Welby, of this extremely important and interesting article will be found in Brain, London, 
1897, vol. xx. p. 232. 

2 T use the word béoplasm as a synonym for living substance, rather than protoplasm, 
because the latter word has come to have a definite histological rather than a physiological 
signification ; and, on the one hand, is used to include portions of cell substance which, for 
aught we know, may not be actually living matter, whilst, on the other hand, it does not 
include the living substance of the cell nucleus, which would be included in the expression 
‘*bioplasm.”’ 


INTRODUCTORY. 869 


up from non-living materials, furnished by the food; and, on the other 
hand, they are broken down into simpler substances, which pass 
away from the tissue into the blood, and ultimately from the body 
with the excreta, or, as in the case of secretory glands, directly into 
secretions. The building-up process, whereby fresh molecules of bioplasm 
are formed, has come to be spoken of as an anabolic change (anabolism, 
assimilation), and the breaking-down process as a katabolic change 
(katabolism, dissimilation). It is clear that these two processes will 
produce opposite effects upon the bioplasm, the one increasing and the 
other diminishing its bulk. But, on the other hand, it is conceivable 
that even within the same cell there may be, at the same time, both a 
building up or anabolic change proceeding, so that fresh molecules of 
bioplasm are being formed, and also a breaking-down or katabolic change, 
affecting molecules which have been formed previously, and the net 
result to the bulk of the tissue may be nil, provided that these two 
processes balance one another; that is to say, the bioplasm, although 
undergoing active metabolic changes, and furnishing products of its 
metabolism to the secretions or to the blood, is not altered in amount 
(autonomous equilibrium). But although both processes are occurring 
simultaneously, they nevertheless do not exactly balance one another, 
there will be as the net result either a gain or loss of bioplasm, «e. the 
bioplasm of the cell will increase or diminish in amount. If every cell 
were entirely composed of bioplasm, this would evidently involve an 
increase or diminution in the bulk of the cell itself. But besides the 
actual bioplasm, all cells contain in a variable proportion products of 
the activity of their bioplasm; “formed material,’ in the sense of 
Lionel Beale, as distinguished from “formative matter.” If these 
products remain within the cell, it may, in spite of the fact that kata- 
bolic processes are proceeding:within it more actively than anabolic 
processes, still increase in bulk, even to a very large extent, but without 
any corresponding increase, indeed even with an actual diminution, of 
its bioplasm. 

Various circumstances may determine the general direction of the 
metabolism of a cell, whether upward in the direction of increased 
anabolism with increase of bioplasm, or downward in the direction of 
increased katabolism with decrease of bioplasm. One such circumstance 
is undoubtedly the amount and nature of the pabulum supplied to the 
cell. Another is to be found in the general physical conditions of the 
environment, such as variations of temperature, supply of water and of 
oxygen, and the like. And in the case of many animal cells we may 
well suppose (and indeed the point may be said to have been determined 
for specific instances) that impulses derived from the nervous system 
may set up respectively, according to their nature, or the nervous channel 
along which they are conveyed, metabolic changes in either an anabolic 
or a katabolic direction. Thus it has been suggested by Gaskell that the 
heart nerves act upon its muscular substance, so as to produce respect- 
ively anabolic changes (vagus fibres, inhibitory impulses) and katabolic 
changes (sympathetic fibres, augmentor and accelerator impulses), accom- 
panied by diminished activity in the one case, by increased activity in 
the other. The possibility must, however, be also borne in mind that the 
same nerve fibres may set up both anabolic and katabolic changes, as 
when a secretory nerve is stimulated, provoking it may be for hours a 
discharge of products of katabolism from secretory cells; for it is in 


S70 METABOLISM. 


such cases necessary to assume a continuous process of anabolism going 
on at the same time within the same cells. 


Upon evidence founded mainly, but not exclusively, upon the investigation 
of certain electrical and visual phenomena, Hering has concluded that in all 
cases where either katabolic or anabolic changes are proceeding in any portions 
of bioplasm, they tend to render the bioplasm more and more resistant to the 
effects of the excitation which is producing the change (reaction) ; that in any 
given cell the longer or more strongly metabolic changes of the one character 
have been proceeding, the greater will be the tendency towards metabolic changes 
of the opposite character, so that even if, as may happen, in consequence of the 
action of an external stimulus (A), anabolic changes are proceeding at first more 
rapidly than katabolic, so that the balance is in favour of the building up 
or assimilation processes, the reaction which is thereby provoked will, after a 
time, by increasing the katabolism of the cell, tend again to produce a condition 
of balance. Only in this case the balance will be struck with the general 
bioplasm of the cell in a condition above par, as compared with that from which 
it was assumed to start (A—allonomous equilibrium). And, mutatis mutandis, 
increased katabolic processes due to external stimuli are (D) assumed to produce 
by reaction an increase of anabolism in adjacent portions of bioplasm, which 
increase becomes eventually sufficient to balance the increased katabolism 
induced by the stimulus, so that again the metabolism of the whole cell strikes 
a balance as it were, but now in a condition below par, as compared with the 
normal (D—allonomous equilibrium). Upon the cessation of the stimulus in 
either case, the tendency, say, to increased anabolism being removed with the 
stimulus, the opposite condition of increased katabolism, which was provoked 
by the increased anabolism, will for a time prevail, and there will be a falling 
off of the general assimilation of the cell, until what may be considered the 
normal condition is again established, the two processes again exactly balancing 
one another. And the same, mutatis mutandis, for the removal of a stimulus 
which was producing a condition of increased anabolism. There is thus 
assumed to be a sort of internal self-adjustment of metabolism in bioplasm. 

It is a part of the theory of Hering that the anabolic and katabolic changes 
in the bioplasm are the direct or indirect cause of many, if not of all, 
physiological phenomena exhibited by living tissue, and that the prevalence 
of one kind of change in any portion of bioplasm will tend to start a 
change of the opposite kind in adjacent portions. But this is a subject 
which we need not here specially concern ourselves with, simce the most 
important application of it to the explanation of physiological phenomena 
concerns the effects produced by the stimulation of the retina by light, and 
will be discussed in the article dealing with this question. 

In connection with this subject, one other point must be borne in mind, 
namely, the possibility, indeed probability, that many metabolic changes in the 
body are not necessarily associated with the building up or breaking down of 
bioplasm, but are effected outside the actual molecules of which the bioplasm 
is composed, although under the influence of the activity of the bioplasm. 
Such changes as these may be distinguished from the metabolic changes of the 
bioplasm itself by the name of “ contact changes,” and they also involve both 
the building up of complex materials and the subsequent breaking down of 
such materials into simpler products associated frequently with oxidation. 
Such contact changes are analogous to those which are produced by organised 
ferments, such as yeast, outside the actual organism, although directly | by its 
activity, and they must be sharply differentiated from the changes which the 
bioplasm itself is at the same time undergoing. This distinction will be 
referred to again in a subsequent section. 

The understanding of the metabolic processes presupposes an acquaintance 
with the composition of the foodstuffs and of the bodystufts, both of which 


BALANCE OF NUTRITION. 871 


have been dealt with in previous articles. So far as the bodystuffs are con- 
cerned (and to a somewhat less extent with regard to the foodstuffs), it cannot 
be said that we possess an acquaintance so intimate as to enable us fully to 
understand the changes which they undergo; and as a consequence it will be 
found that our knowledge of metabolism, in spite of the enormous amount of 
work that has been done to elucidate it within the last five and twenty years, 
is still in an unsatisfactory condition. 


Balance of nutrition.—The first determinations that require to be 
made.in any inquiry into the metabolism of the body are those of its 
incomings and outgoings.1 The incomings of the body consist of food 
and oxygen: the outgoings, of the various excreta, and of the carbon 
dioxide and water lost by the lungs and skin. If the incomings of the 
body exactly balance the outgoings, so that the animal neither gains nor 
loses weight, the body is said to be in complete nutritive equilibrium. 

Sufficient information can be usually obtained regarding the balance 
of metabolism of the body, if the nitrogen and carbon only are determined 
in the ingesta and egesta. 


As an instance of complete equilibrium in a man weighing 70 kilos, 
embracing both the nitrogen and carbon of the ingesta and egesta, the 
following balance table may be given (Burdon Sanderson ”) :— 


INCOMINGS. OUTGOINGS. 

Food. fF yaNe fe: Excreta. Noe) ae 
| 
| | 

Proteids . 100grms.|  15°5 53 Urine - : : 144 i 6206s 
Fat : 2 LOOM Lethe A ano Feces 11 | 10°84 | 
Carbohydrates 250 ,, | ... | 98 Respiration | 208-00 | 
| 

5D 225 15°5 | 225 


We may also have a condition in which the body either gains or 
loses weight, and in which consequently the incomings and outgoings do 
not exactly balance one another, but during which, nevertheless, the 
nitrogen Which is taken into the body, and that which leaves the body, 
may strike an exact balance, while the other elements which compose 
the food and excreta, and especially the carbon, hydrogen, and oxygen, 
may not be similarly balanced. When the nitrogen of the food exactly 
balances the nitrogen excreted, the body is said to be in nitrogenous 
equilibrium. Under these circumstances we may assume that the living 
material of the tissues (which is essentially composed of nitrogenous 
substance) is neither diminished nor increased in amount: whereas, if 
at the same time the other constant elements of the food—the carbon, 
hydrogen, and oxygen—are met with in diminished or increased quantity 
in the excreta, we may assume that substances in the body other than 
the living tissues are either becoming laid on, or becoming diminished 


1 For the methods of determining these may be consulted, C. Voit in Hermann’s ‘‘ Hand- . 
buch,” 1881, Bd. vi. S. 6 e¢ seg., and numerous papers which have appeared since then 
chiefly i in the Arch. f. d. ges. Physiol., Bonn (by Pfliiger, Zuntz, and their pupils), and in 
the Ztschr. f. Biol., Miinchen (by Voit and his pupils). See also v. Noorden, ‘‘ Grundriss 
einer Methodik der Stoffwechsel- Unter suchungen,” Berlin, 1892. For the methods of deter- 
mining the respiratory products, see article ‘ “Chemistry of Respiration”). 

* <* Syllabus of Lectures on Physiology,” 1879. 


872 METABOLISM. 


in amount. These substances are mainly the fats, to a much less 
extent the carbohydrates, whereas the substances which form the 
actual tissues are composed of proteids and nucleo-proteids. 


The, following is an instance of a balance table! of a man weighing 70 
kilos., showing nitrogenous equilibrium only, some of the carbon of the ingesta 
(mostly representing stored fat) not reappearing in the excreta :— 


INCOMINGS. | OUTGOINGS. | 
Foodstuffs. N. C. Excreta. } C. 
| 
| | 
Proteids . 137grms.| 19° |) | Urine : : ae ec: 12°65. 
IRA eee epaae BIEL gaat nae \315°5 | Weeces : . Pi eee! 14°5 
Carbo-hydrates 352 __,, 43, J Respiration : e ee 248°6 
| 19°5 3155 19°5 257 | 


Whether the material which forms the bioplasm of the tissues has an 
essentially different molecular constitution during life from that which is met 
with in it after death, is not certainly known, but is extremely probable. This 
is obviously a point which is difficult of determination, because we cannot 
investigate the material composing bioplasm without previously killing it. 
All we are able to do is to determine, as far as possible, the changes which the 
tissues undergo, by investigating the products which they give off during life. 
Our knowledge of these products has led some physiologists to the conclusion 
that the substance of living material is composed of unstable cyanogen or 
aldehyde compounds, whereas it is well known that dead proteid yields bodies 
of an amide nature.” 


Composition of foodstuffs.—The most important general fact that 
we need concern ourselves with in this place regarding the composition 
of foodstuffs is that, with ordinary mixed diet, they are composed in 
certain not very definite proportions of three chief kinds of organic 
material, namely, proteids, carbohydrates, and fats; in addition to 
which, water and salts are a necessary part of the food. The most 
general proportion of these three primary varieties of foodstuffs 
to one another in ordinary diet is found to be about one part of 
proteid material to from four to six parts of non-proteid, while the non- 
proteid constituents stand to one another in about the proportion of one 
part of fat to from five to ten parts of carbohydrate, this ratio having 
been arrived at by investigating the composition of freely chosen diets 
of persons in various occupations and stations of life. At the same time, 
it must be pointed out that departures from these proportions are by no 
means unfrequently met with, and especially is this the case with 
certain races of mankind, e.g. some of the Asiatic races, where a very 
much larger proportion of non-proteid material is ordinarily taken with 
the diet than is the case with Europeans; whereas, on the contrary, in 
parts of South America and Australia, where meat is plentiful, the pro- 
portion of proteid to non-proteid may be far larger than that above given, 


1, Voit, Hermann’s ‘‘ Handbuch,” Bd. vi. S. 513. The table in the simplified form 
here given is from Neumeister, ‘‘ Lehrbuch,” Jena, 1897, Aufl, 2, S. 344. 
2 Of, Halliburton, this Text-book, vol. i, p. 38. 


COMPOSITION OF FOODSTUFES. 873 


On the whole, however, the above proportions are found to be fairly well 
maintained, the ratio of carbohydrates to fats in the diet varying more 
than the proportion of proteid to non-proteid material. As a general 
rule, it will be found that with the more wealthy classes there is a 
relatively greater amount of proteid and fat as compared with carbo- 
hydrates; whereas with the poorer classes the carbohydrates increase in 
proportion, and the proteids and fats diminish. With a diet’ composed 
of vegetable matter alone, the proportions are liable to be considerably 
modified, since, in order to obtain a sufficient amount of proteid from 
most vegetables, a much larger proportionate amount of carbohydrate 
food is inevitably consumed. On the other hand, since with flesh food 
the amount of proteid necessary for carrying on the metabolic processes 
of the body is much more easily obtained than from vegetable food, 
and since flesh food invariably contains a considerable amount of fat, 
the proportion of proteid and fat to carbohydrate is apt to be much 
greater than the normal when the diet is mainly composed of animal 
matter. 


For the determination of the value of the chief organic materials of the 
foodstuffs in nutrition, the most important point to be ascertained regarding 
their composition is the amount of nitrogen and carbon in each. In round 
numbers, this may be stated as follows :—Proteids contain 15 to 17 per cent. 
N, and 50 to 55 per cent. C!; animal fats, on an average, 76°5 per cent. C ; and 
carbohydrates, such as starch and sugar, 40 to 45 percent. C. Since the amounts 
of proteid fat, and carbohydrates in all the ordinary foodstuffs has been accur- 
ately determined,” and is given in the form of tables, it is not difficult, if the 
amounts of each which are ingested are carefully weighed, to determine by 
calculation the total N and C of the ingesta. For very accurate work, 
however, it is necessary to make direct determinations of the N and C in 
the food taken; this is effected by ordinary chemical methods (that of the 
nitrogen usually by Kjeldahl’s method). 

The amount of flesh or fat which is at any time becoming lost or laid on 
can be easily approximately determined by an examination of a balance table, 
for the nitrogen in the urine represents metabolised proteid, the amount 
of which is arrived at by multiplying the numbers of grms. of nitrogen found 
by 6°25 (since proteids contain 16 per cent. N). Since any excess or deficit 
of proteids represents flesh lost or laid on, the amount of such loss or addition 
can be directly obtained by taking each gramme N in excess or deficit to 
represent 30 grms. flesh (since flesh contains about 3°4 per cent. N) (Voit). 
And, after reckoning off the carbon which the proteid metabolised would contain 
(53 per cent.), any further excess or deficit of carbon in the ingesta would 
represent the carbon of fat lost or laid on, and the amount of this may be 
approximately obtained by multiplying the number of grms. of carbon in the 
excess or deficit by 1°3 (since fat contains about 76°5 per cent. carbon). Thus, 
in the balance table on p. 872, the man under observation retained 39°8 grms. 
C, representing 52 grms. fat laid on. 

The following table (from Bunge) gives the percentage composition of 
some of the chief foodstuffs ; the remainder in each case is mainly water with 
a variable amount of salts—the numbers are taken from Konig. They are 
given in inverse order to the proportion of proteid they contain :— 


1 Argutinsky determined the percentage composition of beef, completely divested of fat 
and dried, to be as follows :—C 49°6, N 15°3, H 6°9, O+S 23:0, ash 5°2 (Arch. f. d. ges. 
Physiol., Bonn, 1893, Bd. ly. S. 345). 

2 Konig, ‘‘Chemie der menschl. Nahrungs-u, Genussmittel,’”’ Berlin, 1882, Aufl. 2. 


874 METABOLISM. 


Foodstuff. Proteid. Fat. Carbohydrate. 
| Apples 04 sot 13 
| Carrots neal 0:2 9 
| Potatoes 2 0-1 20 
| Human milk 2 4 6 
Cabbages . 3°3 07 7 
Cow’s milk : ; 3°4 4 5 
Rice . : j : 8 0:9 ad 
Maize 10 4°6 71 
Wheat 12 ii 70 
| White ofeges . : 13 073,41 é 
Fat pork . ; : 15 37 
Yolk ofeggs  . - 16 32 
| Fat beef . ‘ : 17 26 
Fish (pike) ; ‘ 18 0°5 
| Lean beef . : : 21 les Ss 
| Peas . : : : 23 1°8 58 


Heat value of foodstuffs.—A most important determination to be 
made regarding any diet is its caloric (calorific) value. This is arrived at 
by multiplying the number of grammes of its several organic constituents 
by a number, determined by exact experiment, representing the amount 
of heat produced by the oxidation of 1 grm. of the carbohydrate, fat, or 
proteid to water and carbon dioxide and to urea. Such calorimetric 
experiments were first carried out systematically by Frankland, who 
determined the caloric value of various articles of diet, and his results 
have since been extended and confirmed or amended by various 
observers,” using improved calorimetric methods. 

According to Rubner, the average caloric value of the proteid of the 
aliment is 4124 calories, i.c. 1 grm. proteid oxidised to urea yields 4124 
grm. degrees (or 4:1 kilogram-degrees) of heat; of the fat, 9521 calories 
(9:3 kilogram-degrees); and of the carbohydrate (starch), 4116 calories 
(4:1 kilogram-degrees). Applying these numbers to Voit’s diet (see 
next page), we obtain in round numbers— 


105 grms. assimilated proteid x 4:1 = 430 
OG Vit fat x 19-3 ZO 
500 ,, carbohydrate x 4:1 = 2050 


= 3000 kilo-calories, 


or 3,000,000 calories, as the energy value per diem of the food of a man 
of about 70 kilos., doing hard muscular work. 


This amount is probably a little too high, since the whole of the fat and 
carbohydrate of a mixed diet is not assimilated. Rubner estimates the actual 
production at 2,843,000 calories. Hultgren and Lantergren, however, found 
that Swedish workmen, of an average weight of only 67 kilos., consumed on an 
average per diem 159 grms. proteid, 93 grms. fat, and 570 grms. carbohydrate, 
which, even allowing for the non-assimilation of a certain proportion of each, 
would still give a higher caloric value for the total foodstuffs. Probably, 


1“*On the Origin of Muscular Power,” London, Edinburgh, and Dublin Phil. Mag., 
London, 1866, vol. xxxii. p. 182. 

2 Stohmann, Journ. f. prakt. Chem., Leipzig, 1879, Bd. xix. 8.115; Ztschr. f. Biol., 
Miinchen, 1894, Bd. xxxi. S. 364; Danilewsky, Arch. f. d. ges. Physiol., Bonn, 1885, Bd. 
xxxvi. S. 237; Rubner, Ztschr. f. Biol., Miinchen, 1883, Bd. xix. S. 313; 1885, Bd. xxi. 
S. 250 u. 337; 1886, Bd. xxii. S. 40; 1894, Bd. xxx. 8S. 73. 


MINIMAL AMOUNT OF PROTEID IN FOOD. 875 


therefore, 3000 kilo-calories may be taken as a fair average for the caloric 
value of the ingesta of a man weighing about 70 kilos., which would give 
about 43 calories for each kilogram body weight.’ 

In women the amount is somewhat less than this, both absolutely and also 
relatively. In children, though absolutely less, it is relatively greater. 


Since the combustion of 1 grm. fat produces 9°3 kilo-calories, and the 
combustion of 1 grm. proteid to urea CO, and H,O and of 1 grm. starch 
to CO, each produces 41 kilo-calories, the combustion of 100 grins. fat 
will produce an equal amount of energy with the combustion of 227 grins., 
either of proteid or of starch. This amount, therefore, of proteid or of 
starch is said to be of the same “isodynamic value” as 100 grms. fat. 
It has been shown by the carefully conducted calorimetric investigations 
of Rubner2 that the isodynamic values are as nearly as possible the 
same, whether the combustion occurs in air, or in the tissues of the 
animal body.® 

Minimal amount of proteid necessary in food.—There has been 
much disputation as to the minimal amount of proteid which it is 
possible for a man in health and doing work to take in his diet in the 
course of twenty-four hours. Ranke gave as a normal diet for an 
average man (70 kilos.) not engaged in muscular work, 100 grms. of 
proteid, 100 grms. of fat, and 240 grms. of carbohydrate.* Voit 
allowed for a man of 70 to 75 kilos., doing ten hours’ muscular 
work, 118 grms. of proteid, 56 grms. of fat, and 500 grms. of carbo- 
hydrate. It has, however, been shown that, provided the non-proteids 
in the diet are increased—not only in proportion to the caloric value of 
proteid withdrawn, but considerably more than in such proportion—a 
man can maintain equilibrium and can do work upon considerably less 
proteid than that allowed in the diets of Ranke and of Voit. 


Thus Hirschfeld (70 kilos.)® found that he could maintain himself for a 
considerable time in perfect health with a diminution of proteid down to 
75 grms., or even for a time down to 49 grms. per diem, but under these 
circumstances it was necessary to increase enormously the amount of non- 
proteid and especially of carbohydrate material taken with the diet. 


1 Hultgren and Lantergren, working with Tigerstedt, found the heat value of the food 
of six persons living on a freely chosen diet to vary from 33 to 49 calories per kilogramme. 
They found that the heat value of the proteid was about 16 to 19 per cent. of the total 
heat value of the food, that of the fat being about 21 to 24 per cent., and that of the 
carbohydrate about 60 per cent. Ranke’s diet (vide infra), with a heat value of only 
2,365,000 calories, is for a man performing no muscular work. 

2 Zischr. f. Biol., Miimchen, 1894, Bd. xxx. 8. 73. 

3 A more complete account of the heat values of the foodstuffs is given in the article on 
‘‘ Animal Heat” in p. 833. For the influence of food on the respiratory exchange, see 
article ‘“‘Chemistry of Respiration,” p. 717; see also Magnus-Levy, Arch. f. d. ges. 
Physiol., Bonn, 1893, Bd. ly. S. 1. 

4To this. may be added 25 grms. salts and 2535 grms. water (including that contained 
in the solid food). These several constituents are contained in a daily ration of 250 grms. 
meat, 400 grms. bread, 70 grms. starch or sugar, 100 grms. fat, 10 grms. salt, and 2100 
water (J. Ranke, ‘‘ Die Ernahrung des Menschen,” Miinchen, 1876). 

5 Such a diet contains about 18°3 grms. N, and about 328 grms. C, whereas Ranke’s 
diet contains about 15°5 grms. N, and about 220 grms. C. It should be added that about 
13 grms. of the 118 grms. proteid of Voit’s diet is not absorbed or assimilated, so that the 
available proteid is about 105 grms. This closely corresponds with the results of Bleibtreu 
and Bohland (with Pfliiger), who give 1°5 grms. per kilo. body-weight. This would be a 
little over 105 grms. for a man weighing 70 kilos. (Arch. f. d. ges. Physiol., Bonn, 1886, 
Bd. xxxviii. S. 1). In Hultgren and Lantergren’s observations the actual amount of the 
ingested proteid which underwent metabolism averaged 101°3 grms. 

6 Arch. f. d. ges. Physiol., Bonn, 1887, Bd. xli. S. 533; and 1889, Bd. xliv. S. 428; 
also Virchow’s Archiv, 1888, Bd. exiv. S, 301. 


876 METABOLISM. 


Klemperer! reduced the amount of proteid in his own diet to as little as 
25 grms. per diem, but required 262 germs. fat, and 406 grms. carbohydrate 
(with a total caloric value of more than 5,000,000 calories) to maintain 
equilibrium. 

I. Munk brought a dog into nitrogenous equilibrium with a diet con- 
sisting mainly of proteid. If, now, one-half the proteid of the diet was 
removed and replaced by non-proteid, an amount of non-proteid having a 
caloric value of about two-fifths more than that of the proteid removed was 
required to maintain equilibrium ; and the more the proteid removed from the 
diet, the greater the proportionate amount of non-proteid required. Ultimately, 
the amount of proteid was reduced to 1:5 grms. per kilo. body-weight ; under 
these circumstances an amount of non-proteid, twelve to fifteen times the 
caloric value of the proteid removed, was required to maintain equilibrium.? 
After the lapse of some weeks, the animal failed properly to digest the large 
amount of non-proteid required, and it became necessary to reduce this and 
increase the proteid. 

The amount of nitrogen taken in these experiments was distinctly less 
than the amount which would be lost in the fasting condition. 

Of the two chief kinds of non-proteid food, v. Noorden and Kayser? have 
found that carbohydrates are of greater value as proteid-sparers than fats. In 
a mixed diet, therefore, containing just enough proteid and non-proteid for 
the needs of the economy, fats cannot be substituted for their caloric 
equivalent of carbohydrates without loss of proteid occurring. Gelatin is of 
still greater value as a proteid-sparing food than are either fats or carbohydrates 
(see p. 878), and by its use, although it cannot be built up into tissue, the 
amount of tissue proteid lost from the body can be reduced, according to Voit, 
to about the half of that which is normally lost, and which on Voit’s estimate 
amounts to about 33 grms. daily,* or 1 per cent. of the actual living substance.® 
The importance of gelatin as an article of diet will be specially treated of 
later on.® 


In spite of such experiments, it may be doubted whether a diet which 
includes considerably less proteid than 100 grms. for the twenty-four 
hours could maintain a man of average size and weight for an indefinite 
time. It has frequently been asserted that many Asiatics consume a 
very much smaller proportion of proteid than is the case with Europeans. 
The inhabitants of India, Japan, and China chiefly consume rice as the 
normal constitution of their diet, which contains relatively little proteid ; 
and this has been advanced as an argument in favour of the view that 
the minimal amount of proteid is much less than that ordinarily given 
as essential to the maintenance of nutritive equilibrium. It must, 
however, be stated that we have no definite statistics to show that, in 


1 Arch. f. Physiol., Leipzig, 1889, S. 361. Similar experiments have been made by 
Peschel (Diss., Berlin, 1890) and Graham Lusk, Zéschr. f. Biol., Miinchen, 1891, Bd. xxvii. 
S. 459. See also E. Voit, Miinchen. med. Wehnsehr., 1889, S. 748; and C. Voit, ibid., 
1891, S. 195. 

* Arch. f. Physiol., Leipzig, 1891, S. 338 (Verhandl. d. physiol. Gesellsch.) and 
Virchow’s Archiv, 1893, Bd. cxxxii. S. 91. See also Rosenheim, Arch. f. d. ges. Physiol., 
Bonn, 1893, Bd. liv. S. 61; and Ritter, Miinchen. med. Wehnschr., 1893, Nos. 31 and 32. 

3 Arch. f. Physiol., Leipzig, 1893, S. 371. 

* The half of this amount, since it can be replaced by gelatin, is set down by Voit to 
disintegration of ‘‘circulating proteid ” instead of actual ‘tissue proteid.” 

° Hermann’s ‘‘Handbuch,” Bd. vi. S. 302, and Ztschr. f. Biol., Miimchen, 1889, Bd. 
vii. S. 284. 

 Pagliese, Centralbl. 7. Physiol., Leipzig u. Wien, 1897, S. 329, has found that fats, 
carbohydrates, and gelatin, not only diminish the amount of the nitrogen excreted, but 
also the phosphoric acid, and this even in a greater proportion, and probably by diminish- 
ing the waste of the nucleo-proteids of the tissues. 


CONSTITUTION OF DIETS. 877 


proportion to their body weight, Asiatics doing the same amount of work 
as Europeans require a less amount of proteids ; indeed, such evidence as 
is forthcoming is rather in favour of the opposite conclusion.? 


The following table (from Hultgren and Lantergren) gives the average 
amounts of the proteids, fats, and carbohydrates in freely chosen diets of 
workmen of different countries, together with the total heat values of such diets : 


25 Carbohy- Kilo- 
Proterd: Fat. drate. calories. 
laitey Syietin sith Bild Spud pin| boAlt 
‘Big workmen (Erisman) .| 131°8 19°7 583°8 | 3675-2 
Moderately + Munich workmen (Forster) soe etc Sib tra 4: 3174°1 
hard work | | 
| ie workmen (H. and L.) . | 134:4 79°4 522°8 3436 
Hard work | Swedish workmen (H. and LAS 110 | 714 4726 


With these may be compared the following :— 


. Carbohy- Kilo- 
Proteid. wh drate. calories. 
Soldiers on active service (Voit) . 145 100 500 3574°5 


The average proportion of proteid to non-nitrogenous constituents of the 
food is given by Hultgren and Lantergren at 1:427 by weight, and 1: 4-95 


by heat value; of fat to carbohydrate at 1: 634 by weight, and 1: 2:80 by 
heat value. 


The manner in which the proteid and non-proteid constituents of 
the diet are most advantageously taken into the body, or, in other words, 
the constitution of dietaries, forms a subject belonging more properly to 
the domain of personal hygiene. It would, moreover, occupy far too 
much space to discuss at all adequately the constitution of diets of 
different people and in different countries. It is sufficient to state 
that under ordinary circumstances the proteids are taken in such 
forms as flesh, egg, and cheese, bread and other cereals, and leguminous 
foods, the fat in the form of meat-fat and butter, and the carbo- 
hydrate in the form of starch or cane-sugar derived from or contained 
in vegetable food. With a purely vegetarian diet the proteid 
of the food may be derived largely from the leguminous plants and 
to a somewhat less extent from the cereals, and the fat from the seeds 
of plants.2, We may now proceed to consider the effects upon nutrition 
of some of the more important constituents of the diet. 


1Cf. Kumagawa, Virchows Archiv, 1889, Bd. exvi. S. 370; Kellner and Mori, Ztschr. 
f. Biol., Miinchen, 1889, Bd. xxv. S. 102; I. Munk, zbid., 1893, Bd. exxxii. S. 91. 

* For statistics concerning diet see J. Ranke, ‘‘Die Ernahrung des Menschen,” 
Miinchen, 1876; C. Voit in Hermann’s ‘‘ Handbuch,” Bd. vi. (‘‘ Physiologie des 
allgemeinen Stoffwechsels und der Ernaihrung”), Leipzig, 1881; Konig, ‘‘Chem. d. 
mensch]. Nahrungs-u. Genussmittel,” Berlin, 1882, Aufl. 2; I. Munk and Uffelmann, 
**Ernihrung des Menschen,” Wien u. Leipzig, 1887, in which also the literature of the 
subject up to that date will be found; Scheube, Witth. d. deutsch. Gesellsch. f. Nat.-u. V élkerk. 
Ostasiens, Yokohama, 1882, No. 24, and Arch. f. Hyg., Miinchen u. Leipzig, 1884, Bd. i. S. 
352 (diet of Japanese) ; Hultgren and Lantergren, *‘ Untersuch. ti. d. Ernaihr. Schwedischer 
Arbeitern,” Stockholm, 1891 ; Studemund, Arch. f. d. ges. Physiol., Bonn, 1891, Bd. xlviii. 
8.578 ; OhImiller, Zischr. f. Biol., Miinchen. 1884, Bd. xviii. S. 393; G. Bunge, ‘‘ Der Vege- 
tarianismus,” Berlin, 1885; Kumagawa, Virchow’s Archiv, 1889, Bd. exvi. S. 370; Albertoni 
and Novi, Arch. ie d. ges. Physiol., “Bonn, 1894, Bd. lvi. S. 213 (criticised by Hultgren, ibid., 
1895, Bd. lx. S. 205). Diet statistics will also be found in most text-books of physiolog 


878 METABOLISM. 


Special constituents of the diet.—Proteids.—Proteids are chiefly 
taken in the diet in the form of egg-albumuin, vitellin, myosin, casein, 
the proteids of cereals and of leguminous seeds (mainly globulins). The 
nutritive value of the proteids from any one of these sources is pretty 
nearly the same, with the exception that somewhat less of the proteid 
of vegetable food is digested and assimilated than that of animal origin, 
and the less, the larger the amount of cellulose which is contained in the 
food. 

Peptones and albumoses have about the same caloric and nutritive 
value as the proteids from which they have been formed. Certain 
proteids are assimilated and have the same nutritive value, if injected 
into the blood vessels or under the skin, as when digested and absorbed 
from the intestines. This is the case with serum-albumin and serum- 
globulin, and also with acid or alkali albumin (even if prepared from 
ego-albumin) and phytovitellin.? Other forms of proteid are not thus 
directly assimilable, but on injection appear at once in the urine. Such 
are ego-albumin,® casein,* peptone, and albumoses. Haemoglobin must 
also be reckoned with these, although if injected as blood (with the 
blood corpuscles intact), it remains intact. If injected dissolved in 
water or in serum, it becomes partly broken up and converted into bile 
pigment and partly appears in the urine as hemoglobin. 

Most, if not all, proteids contain sulphur, and the nucleo-proteids 
contain phosphorus; an increase of sulphates and sometimes of phos- 
phates in the urine may therefore be expected, if their metabolism is 
increased. The metabolism of proteids will be subsequently dealt with. . 

Gelatin.—Gelatin, although its elementary composition is very 
nearly the same as that of proteids, and although it becomes, like 
proteids, converted into peptones by digestion, and after being assimi- 
lated is oxidised into urea CO, and H,0O, is different from proteids in 
its chemical constitution (see “Chemical Constituents of Body and 
Food, pp. 31 and 70), and cannot wholly replace proteid as an article 
of diet. This arises from the fact that the bioplasm of the tissues 
is unable to be produced from it. In spite, therefore, of its con- 
taining nitrogen and all the elements of the proteid molecule, it is a 
non-proteid food, and takes its place as such along with the fats and 
carbohydrates. Like them also it acts as a proteid-sparer, so that a 
certain amount of proteid can be removed from the diet and replaced 
by gelatin ; about twice as much of this must; however, be added, as 
proteid is removed. As a proteid-sparer, gelatin acts more efficiently 
than carbohydrates, and still more than fats. This is shown by an 
experiment by Voit upon a dog weighing 32 kilos., which had been 
maintained very nearly on nitrogenous equilibrium by a daily allowance 

1 Politzer, Arch. f. d. ges. Physiol., Bonn, 1885, Bd. xxxvii. 8. 301. 

2 Plész and Gyergai, Arch. f. d. ges. Physiol., Bonn, Bd. ix. 8. 325, and Bd. x. S. 536 ; 
Maly, ibid., Bd. ix. S. 605; Adamkiewicz, Virchow’s Archiv, Bd. lxxv. S. 144; Stokvis, 
Centraibl. f. d. med. Wissensch., Berlin, 1864, S. 596; Lehmann, Virchow's Archiv, 1864, 
Bd. xxx. 8. 593; Ponfick, Virchow’s Archiv, 1875, Bd. lxii. S. 273; Forster, Ztschr. 
f. Biol., Miinchen, 1875, Bd. xi. 8S. 517; Tizzoni, Arch. ital. de biol., Turin, 1884, Bd. 
vi. S. 395; Neumeister, Sifzungsb. d. phys.-med. Geselisch. zu Wiirzburg, 1889, S. 64 ; 
Atschr. f. Biol., Miinchen, 1891, Bd. xxvii. S. 309. 

3 Bernard, ‘‘ Lecons sur les propr. physiol. etc.,”’ Paris, 1859, tome i. p. 467. 

4 Runeberg, Deutsches Arch. f. klin. Med., Leipzig, 1879, Bd. xxiii. S. 68. 

> According to Voit, one-fifth of the ordinary amount of proteid may be so replaced. I. 
Munk, however, in the dog got at least two-thirds of the proteid of the food replaced 
by gelatin with maintenance of equilibrium (Arch. f. d. ges. Physiol., Bonn, 1894, Bd. lviii. 
S. 309, and Bd. 1xi. S. 607). 


——— =" 


SPECIAL ARTICLES OF DIET. 879 


of 500 grms. of meat. On removing 100 grms. of this from the diet, and 
replacing it by 200 grms. of gelatin, there was a gain of nitrogen to the 
body representing the putting on of 44 grms. of flesh, whereas when the 
100 grms. of meat was replaced by 200 grms. of fat, or by 250 grms. of 
starch, there was a loss of nitrogen representing a loss of flesh to the 
amount respectively of 50 and 39 grms. 

The following experiments of Voit on a dog are also instructive. 
The numbers represent grammes :— 


| | 
| Expt. Lean Meat. | Gelatin. Flesh lost or gained. | 


ut f 500 0 22 

ha: 500 | 200 +54 
‘ ( 2000 | 0 +30 
sli | 2000 200 +376 
js 200 20 | =118 
| ly 200 | 300 - 82 
| (| 200 | 200 +25 
Pe U ce ia ioanpesete 


| 
| 


That it cannot wholly replace proteid is shown by the fact that 
even when very large quantities are given either alone or in combination 
with fat and carbohydrate, an excess of nitrogen appears in the excreta 
—in other words, there is still a loss of flesh from the body To a 
certain extent gelatin will act as a fat-sparer, 7.e., when given along 
with proteid, it may prevent the oxidation of body fat, but its activity in 
this respect is far below that of either fats or carbohydrates.2— Even 
the collagenous tissues can apparently not be formed from gelatin 
ingested, since this wholly appears (as urea, etc.) in the excreta; these 
tissues must therefore be formed, like all others, from proteid food.’ 
Gelatin is also not assimilated if injected into the blood or under the 
skin ; it appears at once in the urine.* 

Nucleins and nucleo-proteids, as well as lecithins, are found in all 
forms of mixed diet ; and although nuclein is not digested by the gastric 
juice, nor, according to Bokay,> by artificial pancreatic juice, there are 
reasons for believing that a part at least of the nuclein of the food is 
absorbed and converted in the body into other substances. It is found, 
for example, that the ingestion of foodstuffs containing much nuclein 
causes a marked increase of uric acid in the urine,’ and, as we shall 
show later on, there is strong reason to believe that the iron necessary 
for the formation of hemoglobin is derived from some forms of nuclein. 


1 For the evidence of this, see C. Voit, op. cit., S. 122. 

aCe \Viob.op. cit. 9. 126. 

3 An interesting historical account of the question of gelatin as an article of diet is 
given by Voit (op. cit., S. 395). 

4Cl. Bernard and Barreswil, Jowrn. de pharm. et chim., Paris, 1844, Sér. 3, tome v. 

. 425. 

Eigse Ztschr. f. physiol. Chem., Strassburg, 1877, Bd. i. S. 157. 

5 Horbaczewski, Sttzungsb. d. k. Akad. d. Wissensch., Wien, 1891, Bd. c. Abth. 3, 8. 78. 


880 METABOLISM. 


The phosphorus of any nuclein which is absorbed is probably converted 
into phosphoric acid, and excreted as phosphates by the urine. There 
is no evidence that the nuclein which is absorbed is taken up by the 
tissues, and by them again converted into tissue nucleins; it is more 
probable that these arise by independent synthesis from proteid and 
phosphates. That this may occur was shown by Miescher,’ who found 
in the case of the salmon, which travels from the sea to the upper 
Rhine, there to deposit its spawn, and which during the whole period of 
its journey and sojourn in the river, lasting some weeks or even months, 
takes no food whatever (the alimentary canal being always found empty), 
that the ovaries increase in size at the expense of the muscular tissue. 
Now the ovaries, being mainly composed of ova, contain large quantities 
of nuclein and lecithin, whereas the muscles contain mainly ordinary 
proteids and very little of these substances; the latter must therefore 
be formed by synthesis, the materials for such synthesis being derived 
from the proteids, the fats, and the phosphates of the muscles. 

Amido- acids. — Experiments to determine the nutrition, and 
especially the proteid-sparing value of amido-acids, have chiefly been 
made with asparagin, which occurs in some quantity in certain vegetables. 
The general result of these inquiries is to show that in herbivora (rabbit, 
goose, sheep), the amido-acids can act as proteid-sparers, whereas in 
earnivora (dog) and omnivora (rat) they have not proteid-sparing 
effects when added to the diet.? 

Creatine has been found to have no nutritive value. If given with 
the food, it appears wholly in the urine as creatinine.* 

Carbohydrates.—Apart from the small amount of glycogen or sugar 
which may be contained in flesh foods, and from the lactose of milk, the 
carbohydrates of the food are wholly derived from the vegetable king- 
dom. The chief carbohydrate constituents of an ordinary diet are starch 
and cane-sugar, with a certain amount of grape-sugar when there is 
much consumption of certain fruits. Neither starch (in solution) nor 
cane-sugar (Bernard) is directly assimilable when injected into the blood 
vessels, and the same is true for maltose and lactose. These sub- 
stances all appear under such circumstances at once in the urine. 

On the other hand, dextrose can be directly assimilated, even in large 
amounts. It is necessary that the injection should be conducted slowly, 
so that the liver should have time to convert it into glycogen before the 
proportion of dextrose in the blood much exceeds about 0:2 per cent. 
Injected too rapidly, or in too large doses (more than 1 grm. per kilo. 
body weight), glycosuria results ;° and if its elimination by the kidneys 


1 Arch. f. Anat. u. Entweklngsgecch., Leipzig, 1881,S.193 ; and ‘‘Statistische u. biol. Beitr. 
z. Kenntniss vom Leben des Rheinlachses,” 1880 (quoted from Bunge’s ‘‘ Handbuch”). 

2 Weiske, Ztschr. f. Biol., Miinchen, 1879, Bd. xv. S. 261; 1881, Bd. xvii. S. 415 ; 
1884, Bd. xx. S. 277; 1894, Bd. xxx. S. 254; Zuntz and Bahlmann, Arch. /. 
Physiol., Leipzig, 1882, S. 424 (Verhandl. d. phys. Geseilsch.) ; Potthast, Arch. f. d. ges. 
Physiol., Bonn, 1883, Bd. xxxii. S. 280 ; I. Munk, Virechow’s Archiv, 1883, Bd. xciv. 8. 486 ; 
and 1884, Bd. xeviii. S. 364; Mauthner, Ztschr. f. Biol., Miinchen, 1892, Bd. xxviii. 
S. 507; E. Voit, Sitzwngsb. d. k.-bayer. Akad. d. Wissensch. zu Miinchen, 1883, S. 401 ; 
Ztschr. f. Biol., Miinchen, 1892, Bd. xxvii. S. 492; 1893, Bd. xxix. S. 125; Gabriel, ibid., 
Sh UG 

3 Meissner, Ztschr. f. rat. Med., 1868, Bd. xxxi. S. 283. 

4 According to Dastre (Arch. de physiol. norm. et path., Paris, 1889, p. 718), galactose is 
directly assimilable. 

5 Biedl and Kraus (Wien. klin. Wehnschr., 1896, S. 55) state, however, that they were 
able to inject as much as 200 to 300 grms. of grape-sugar, in 10 per cent. solution, into the 
vein of a man, without producing either polyuria nor any but a slight temporary glycosuria. 


SPECIAL CONSTITUENTS OF THE DIET. 881 


be prevented, as by tying the ureters, the excess of sugar under- 
goes changes which result in the formation of lactic acid, acetone, 
diacetic acid, and other substances, the production of which is 
accompanied by convulsions, and eventually coma, as in severe natural 
diabetes.1 

Very large amounts of starch can be taken into the alimentary canal, 
and corresponding amounts of dextrose absorbed into the blood, without 
producing glycosuria in a normal animal. But if the assimilation 
powers have been reduced by starvation, glycosuria is found to occur on 
the ingestion of a large amount of starch.2 On the other hand, if cane- 
sugar, maltose or lactose, and even levulose, are taken by the mouth in 
large quantities, even without a previous starvation period, part of the 
sugar ingested appears in the urine (alimentary glycosuria).’ This is 
apparently due to the fact that the blood vessels of the intestine cannot 
carry away all the absorbed sugar with sufficient rapidity to the liver, 
and some of it consequently passes to the general circulation by way of 
the thoracic duct, and thus to the kidneys, which always immediately 
eliminate any excess of sugar in the blood passing through them. 
Glycosuria also occurs when sugar solutions are injected into the large 
intestine of dogs.® 

Cellulose is not readily digested by carnivora nor by man, but in 
some forms of food (carrots, cabbage, celery, lettuce) a considerable 
proportion of the cellulose present may become dissolved and absorbed ; ° 
in herbivora it undergoes digestion, and is eventually absorbed as 
dextrose. Its chief value in the diet of animals seems, however, to 
be due to its action in promoting peristalsis of the intestines. Rabbits 
die from inflammation of the intestines if devoid of cellulose ;its place can 
be supplied in them by horn-shavings, which have the same mechanical 
effect. In carnivora and man this is not so important, as the gut is 
shorter, but probably the cellulose of mixed food tends to prevent 
constipation. A purely milk diet is well known to be constipating 
(Bunge). 

The fate of the carbohydrates after assimilation will be treated of in 
a special section on carbohydrate metabolism. 

Fats are taken in largely in the form of animal fat (fats of flesh and 
milk), but also largely, especially in some countries, in the form of 
vegetable fats, such as olive oil and the fats met with in certain seeds. 
In the last-named form they are protected by cellulose, and are far less 
easily digested and assimilated. The changes which they undergo in 
the processes of digestion and absorption have already been fully con- 
sidered (pp. 445-465), also their caloric value, and their importance as 
proteid-sparers. Their assimilation to the natural fat of the body, and 
their formation within the body, will be treated of subsequently. 

Fatty acids and soaps have been shown by I. Munk (in dogs) to 
have very nearly the same nutritive value as the fats from which they 

1V. Harley, Arch. f. Physiol., Leipzig, 1893, Suppl., S. 46. 

* Hofmeister, Arch. f. exper. Path. u. Pharmakol., Leipzig, 1889, Bd. xxv. S. 240 ; and 
1890, Bd. xxvi. 8. 355. 

> Worm-Miiller, Arch. f. d. ges. Physiol., Bonn, 1884, Bd. xxxiv. S. 576; Hofmeister, 
Arch. f. exper. Path. u. Pharmakol., Leipzig, 1889, Bd. xxv. S. 240; C. Voit, Ztschr. f. Biol., 
Miinchen, 1892, Bd. xxviii. 8S. 265; Miura, zbid., 1896, Bd. xxxii. S. 281. 

4 Ginsberg, Arch. f. d. ges. Physiol., Bonn, 1889, Bd. xliv. S. 306. 

5 Kichhorst, zbid., 1871, Bd. iv. 8. 601. 


6 Weiske, Ztschr. f. Biol., Miinchen, 1870, Bd. vi. S. 456; Knierem, zbid., 1885, Bd. 
xxi. S. 67. See also Luntz, Arch. f. d. ges. Physiol., Bonn, 1891, Bd. xlix. 8. 477. 


VOL. 1.—56 


882 METABOLISM. 


are formed. This has, however, been already discussed (p. 750), and 
will be again referred to later on. 

Glycerin has been found to act in some measure as a fat and 
carbohydrate-sparer, but not as a proteid-sparer! Of the total 
amount ingested, from 21 to 37 per cent. is secreted in the urine 
unaltered, when given in large doses.” The sparing effect of glycerin 
on the conversion of liver glycogen into sugar will be subsequently 
referred to. 

Alcohol.—The nutritive value of alcohol has been the subject of 
considerable discussion, and not a few experiments. Some of these 
tend to show that in moderate non-poisonous doses it acts as a non- 
proteid food in diminishing the oxidation of proteid, doubtless by 
becoming itself oxidised.* Its action, however, in this respect is 
relatively small, and indeed a certain proportion of alcohol ingested 
is exhaled with the air of respiration. Moreover, in large doses, it 
may act in the contrary manner, increasing the waste of tissue proteid.* 
It cannot, in fact, be doubted that any small production of energy 
resulting from its oxidation is more than counterbalanced by its 
deleterious influences as a drug upon the tissue elements, and especially 
upon those of the nervous system. 

It is of interest, in connection with this subject, to point out that 
alcohol has been regarded by some physiologists as probably formed 
at a stage in the metabolism of carbohydrates prior to their complete 
oxidation, traces of alcohol having been obtained from fresh tissues by 
distillation with water.® 

Inorganic substances.—Mineral salts, especially chloride of sodium 
and phosphates of lime and of the alkalies, are essential parts of 
any diet. The following table from Bunge gives the proportions 


K,0. | Na,O. | Cad. | MgO. | Fe,0;. | P.05. Cl. 
Beef . i ; - ; 1°66 | 0°32 0029 | 0-15 0°02 1°83 0°28 
Wheat . : ; | 0°62 0:06 0°065 | 0°24 0°026 | 0°94 2 
Potato : : F : | 2°28 O-1l 0100 | 0°19 07042 | 0°64 0°13 
White ofege : | 44 1°45 07130 | O13 0°026 | 0°20 1°32 
Peas . - : ; 5) oaledS 0:08 0°137 | 0°22 0°024 | 0:99 2 
Human milk. 4 Ors 0°17 | 0-243 | 0°05 | 0-003 0°35 0°32 | 
Yolk of egg : : : | 0:27 | 0°17 | 0-380 | 0:06 | 0°040 | 1°90 | 0°35 
Cow’s milk - : 5) |e 7/ 1:05 1:51 0°20 | 0:003 | 1°86 1°60 


| 


1]. Munk, Virchow’s Archiv, Bd. lxxvi. 8S. 119; Bd. lxxx. S. 39. 

* Tschirwinsky, Zéschr. f. Biol., Miinchen, 1880, Bd. xv. ; Arnschink, zbid., 1888, Bd. 
xxiii. S. 413. 

3 Strassmann, Arch. f. d. ges. Physiol., Bonn, 1891, Bd. xlix. S. 315. Chittenden 
(Journ. Physiol., Cambridge and London, 1892, vol. xii. p. 220), experimenting upon 
dogs, obtained very little influence on proteid metabolism. For the earlier literature 
of this question, cf. C. Voit, op. cit., pp. 169 and 415. 

4 Miura, Ztschr. f. klin. Med., Berlin, 1892, Bd. xx. S. 137. I. Munk obtained similar 
results upon dogs (Verhandl. d. Physiol. Gesellsch., 1878-79, No. 6 in Arch. f. Physiol.). 

° Hoppe-Seyler and Rajewsky, Arch. f. d. ges. Physiol., Bonn, 1875, Bd. xi. S. 
122: 


INORGANIC SUBSTANCES. 883 


per cent. in which the different salts of the ash occur in dried food- 
stuffs. 

Animals from whose food the salts have been extracted, some- 
times die even more rapidly than animals which have been altogether 
deprived of food, with the supervention of various symptoms indicating 
a disturbance of the central nervous system and of the digestive system.? 
This more rapid end of such animals is due, according to Bunge, 
to chronic acid-poisoning, produced by the oxidation of the sulphur 
of the proteids ; such acid being normally neutralised by the basic salts 
(phosphates, carbonates, and alkali-albuminates) taken in with the food, 
whereas in the absence of these, basic substances are removed from the 
tissues to take their place. The experiments of Lunin (in Bunge’s 
laboratory) upon mice fed respectively upon salt-free food, or upon the 
same food to which sufficient sodium carbonate was added to exactly 
neutralise the sulphuric acid which would be formed in the oxidation 
of the proteid of the food, seem to show that Bunge’s conjecture is 
correct ; for such animals lived considerably longer than those to which 
no soda was given, or than those to which it was given combined with 
chlorine. This, however, is probably not the whole explanation, for in 
both the dog and man the faculty of resisting the effects of acids in the 
ingesta depends in part, at least, on their neutralisation by ammonia, 
which is derived from metabolised proteid.® 

It would appear that some at least of the mineral matters of the 
food must be in their natural condition, which is probably that 
of combination with the proteid substances. For Lunin found that 
although mice will live indefinitely on desiccated milk, yet if they 
are given an artificial food consisting of a mixture of salt-freed casein and 
lactose, to which have been added the same inorganic salts which are 
present in the original milk, the animals will die at about the same period 
as if sodium carbonate alone had been added to the casein and sugar.® 

As Bunge has pointed out, the addition of chloride of sodium to the 
ordinary food appears to be essential to the well-being of all animals 
the food of which contains a large proportion of potassium salts, as 
occurs in most vegetables. In conformity with this, we find that those 
races of mankind which subsist mainly on vegetable food find salt an 
absolute necessity of life; and that the same is the case with herbivorous 
animals is shown by the fact that these are often found to travel 
hundreds of miles to reach a place where salt is to be found (salt-licks). 
Carnivorous animals, on the other hand, and those herbivora which 
consume plants and herbage which do not contain a great excess of 
potassium salts, show no such inclination to seek salt. The same is true 
for those races of mankind who live almost exclusively on fish or flesh, 


1 Note especially the small amount of Na,O in wheat and peas; the large amount of 
CaO in milk and egg yolk, and the very small amount of iron in milk. On the other 
hand, the ash of the foetus contains a very large proportionate amount of iron. 

2 Forster, Ztschr. f. Biol., Miinchen, 1873, Bd. ix. 8. 297. 

3 Ztschr. f. Biol., Miinchen, 1874, Bd. x. S. 180. See also ‘‘ Lectures,” pp. 114-118. 

4 Zischr. f. physiol. Chem., Strassburg, 1881, Bd. v. 8. 31. See also Socin, zbid., 1891, 
Bd. xv. 8. 100. 

5 Schmiedeberg and Walter, Arch. f. exper. Path. u. Pharmakol., Leipzig, Bd. vii. 
S. 148 ; Hallervorden and Coranda, ibid., Bd. xii. S. 76. 

6 Somewhat similar conclusions were arrived at by Bunge and Socin from experiments 
upon another artificial food, which had been first deprived of salts, but to which these 
were afterwards added. This food, although apparently containing all needful materials 
for nutrition, was unable to keep the mice which were fed upon it alive. 


884 METABOLISM. 


or on such vegetable food, eg. rice, in which the potassium salts are 
only present in small quantity. It is further noteworthy that the 
peoples who live on an animal diet, without salt, carefully avoid a loss 
of blood when they slaughter the animals, for the blood contains a far 
larger amount of sodium in proportion to potassium than any other tissue 
or organ. The explanation of these facts is thus offered by Bunge !:— 


“The amount of salt which herbivorous animals take in with their food is, 
compared with the weight of the body, generally not much less than that 
consumed by carnivorous animals. On the other hand, there is a considerable 
difference in another constituent of the ash of their food, in the potassium. 
Herbivorous animals take at least three or four times as much of salts of 
potassium as the carnivora. This fact leads me to imagine that the abundance 
of potassium in vegetable food is the cause of the need for salt in the 
herbivora. If, for instance, a salt of potassium, such as potassium carbonate, 
meets with common salt or chloride of sodium in solution, a partial exchange 
takes place—chloride of potassium and carbonate of sodium are formed. Now, 
chloride of sodium is well known to be the chief constituent among the 
inorganic salts of blood plasma. When, therefore, salts of potassium reach the 
blood by the absorption of food, an exchange takes place. Chloride of 
potassium and the sodium salt of the acid which was combined with the 
potassium, are formed. Instead of the chloride of sodium, therefore, the blood 
now contains another sodium salt, which did not form part of the normal 
composition of the blood, or at any rate not in so large a proportion. But the 
kidneys possess the function of maintaining the same composition of the 
blood, and of thus eliminating every abnormal constituent, and any excess of a 
normal constituent. The sodium salt formed is therefore ejected by the 
kidneys, together with the chloride of potassium, and the blood becomes 
poorer in chlorine and sodium. Common salt is therefore withdrawn from the 
organism by the ingestion of potassium salts. This loss can only be made up 
from without, and this explains the fact that animals which live on a diet 
rich in potassium have a longing for salt.” 


In confirmation of this deduction, Bunge found that the addition of 
potassium salts to his diet produced a striking increase in the excretion 
of chlorine and sodium. Thus 18 grms. of K,O, taken in the form of 
phosphate or citrate, caused the loss of an extra 6 grms. of chloride of 
sodium (as well as 2 grms. of sodium in other forms), about one-half of 
the common salt which is contained in the 5 litres of a man’s blood. 
And 18 grms. of potash is an amount much less than may be introduced 
with many important articles of vegetable diet, such as potatoes, which 
contain 20 to 28 grms. K,O in each "1000 germs. of dehydrated material. 
“ Having regard to the important part which salt plays in the organism 
(as in the formation of the digestive secretion, or in dissolving the 
globulins), even a small diminution may be prejudicial to certain ‘fune- 
tions, and may give rise to the need of recovering the loss.” * 

There are two other constituents of the food which need special 
consideration, namely, zvon and lime. 

The amount of iron which is egested is exceedingly small, and it 
may be expected therefrom that ‘the amount present in the food 
under ordinary circumstances would also be small. Stockman has 


? “ Lectures,” translated by Wooldridge, p. 119. 

* Bunge, op. cit., p. 121. The student is referred to Bunge’s original publications 
(GS ‘Lectures” and Zischr. J. Biol., Miinchen, 1874, Bd. x.) for a ‘full and very interesting 
discussion of this important subject. 


INORGANIC SUBSTANCES. 885 


shown that only about 10 mgrms. a day is ingested in an ordinary diet." 
Of this amount, | mgrm.is egested by the urine, the remainder by the feces. 
This cannot, however, represent all the iron metabolised, for the iron of 
the hemoglobin of disintegrated blood corpuscles is retained, mainly by 
the liver, and is no doubt again built up into blood pigment. The nuclei 
of most cells, both animal and vegetable, contain appreciable quantities 
of iron, and in this form, and in the hemoglobin of meat, it must occur in 
most food.2, In both these cases it forms an integral part of the molecule 
of the proteid or nucleo-proteid, and under ordinary circumstances there 
is no inorganic iron, nor any iron salt of organic acid present in the diet. 
Such compounds of iron as are contained in nucleins—such, for instance, 
as the nuclein of the yolk of the egg—have been termed by Bunge hema- 
togens. As this nuclein is the only iron-containing constituent of the 
yolk, it is clear that the hemoglobin of the developing red corpuscles of 
the chick must derive its iron from it. It has further been shown by 
Socin, working in Bunge’s laboratory,’ that in mammals also hemoglobin 
is manufactured when the only iron contained in the food is in the form of 
the same yolk-hematogen, and that the urine of animals (dogs) fed freely 
with egg yolk shows a marked increase in the amount of iron present. 

It is noteworthy, as has been pointed out by Bunge, that the natural 
food of the infant, namely, milk, contains mere traces of iron, although 
the formation of hemoglobin is actively proceeding. This is accounted 
for by the fact that the teetus lays up a store of iron (in its liver and else- 
where) before birth, and gradually draws upon such store for the manufac- 
ture of hemoglobin. Thus Bunge * found 18-2 mgrms. iron per 100 grms. 
body weight in a new-born rabbit, as compared with 3-2 mgrms. per 100 
orms. inan animal twenty-four days old; and Zalesky,’ four to nine times as 
much iron in the liver of a new-born puppy as in that of a full-grown dog. 

In all other respects the composition of the ash of milk nearly 
corresponds with the composition of the ash of the sucking animal, as 
may be seen in the following table from Bunge, which gives the result 
of two experiments :— 


PUPPY. MILK OF BITCH. 

Als B. A’ B. 
KAO. 5 . 11°42 8°50 14°98 10°70 
Na,O : c : 10°64 8°20 8°80 6-10 
CaO. 5 : ‘ 29°52 35°8 27°24 34°40 
MgO. 2 : 1°82 1°60 1°54 1°50 
Fe,0, : : : 0°72 0°34 0°12 0°14 
P.O. Ql, wee 39°42 39°80 34°22 37°50 
Cl : 3 . “ 8°35 7°30 16°90 12°40 


1 Brit. Med. Jouwrn., London, 1893, vol. i. pp. 881, 942 (contains the literature regard- 
ing iron absorption up to that date) ; Journ. Physiol., Cambridge and London, 1895, vol. 
XVili. p. 485; also, with Greig, zbid., 1897, vol. xxi. p. 55. 

2 Bunge, Zischr. f. physiol. Chem., Strassburg, 1885, Bd. ix. 8. 49. For the micro- 
chemical evidence of the presence of iron in cell-nuclei, see Macallum, Proc. Roy. Soc. London, 
1891, vol. 1. p. 277; and Quart. Journ. Micr. Sc., London, vol. xxxviii. p.175. This will 
probably account for the fact that the feces, which includes many disintegrated cells of the 
alimentary passages, sometimes shows a greater percentage of iron than is present in the 
food, although the secretions poured into the intestines only contain iron in minute amounts. 

3 Zischr. f. physiol. Chem., Strassburg, 1891, Bd. xv. S. 93 and 133. 

4 Thid., 1892, Bd. xvi. S. 177. 

5 Ibid., 1886, Bd. x. S. 479 and 495. 


886 METABOLISM. 


In spite of the fact that it is the general experience of members of the 
medical profession, that the administration of iron salts promotes the formation 
of hemoglobin in certain forms of anemia (chlorosis), there is no satisfactory 
evidence that the administered iron enters into the formation of the newly- 
formed hemoglobin, and it has even been denied that the alimentary canal is 
capable of absorbing iron given in such form. The experiments of Kunkel,} 
however, show that if iron salts are administered to animals along with their 
food, the blood, liver, spleen, and other organs exhibit an excess of iron over 
that of control animals. Mall? also obtained distinct evidence of iron 
absorption under like circumstances. When iron salts are injected sub- 
cutaneously into a vein, most of the iron appears at once in the urine, some 
is secreted into the intestine,? but some is stored in the liver and is only 
gradually eliminated. Experiments upon animals, in which the hematogens 
of Bunge have been removed from the food and replaced by iron salts, have 
been attempted,* but have presented serious difficulties.6 Marfori,® however, 
working with Schmiedeberg, obtained a large amount of absorption of iron 
when given to dogs in artificial combination with albumin. Macallum also 
has shown that iron, both in organic and inorganic combination, is absorbed 
by the intestinal mucous membrane.’ 


Lime is taken in and assimilated by the organism, also in all probability 
in the form of organic compounds, probably with proteids.® It oceurs in 
large amount in milk, but in most other forms of foodstuffs it is deficient 
as compared with other constituents of the ash; the leguminosz 
contain more than most foodstuffs. The only food which has the same 
amount as milk is the yolk of egg, which should therefore always 


oD? 
be given to children when milk is either not procurable or cannot be 
= = ” 
digested.” ® 


The withholding of lime from the food of growing animals causes rickets ; 1 
but rickets may occur in children, in spite of their food containing an adequate 
amount of lime.!!_ Probably, owing to abnormal conditions of nutrition, the 
lime is under these circumstances not assimilated. 

In adult animals (pigeons), feeding with foods containing little or no lime 
has been found eventually to cause alterations in the bones, which become 
unusually brittle and thin (osteoporosis).!? 


1 Arch. f. d. ges. Physiol., Bonn, 1891, Bd. 1. S. 11; 1895, Bd. Ixi. S. 595. 

2 Arch. f. Physiol., Leipzig, 1894, S. 456 ; and 1896, S. 49. 

3 Mayer, Diss., Dorpat, 1850, quoted by Bunge. Quincke (Arch. f. Anat., Physiol. u. 
wissensch. Med., 1868, S. 150) failed to find it in an isolated portion of intestine with a 
Thiry fistula, but Macallum (Journ. Physiol., Cambridge and London, 1894, vol. xvi. p. 
268) obtained evidence of it in the crypts of Lieberkiihn. 

4Socin, Ztschr. f. physiol. Chem., Strassburg, 1891, Bd. xv. S. 93; v. Hosslin, Zéschr. 
jf. Biol., Miinchen, 1882, Bd. xviii. S. 612; Hall, Arch. f. Physiol., Leipzig, 1896, S. 142. 

° Consult upon the subject, Bunge, ‘‘ Lehrbuch,” 1894, 3te Aufgabe, S. 83 ; and Wool- 
dridge’s translation ; also Neumeister, ‘‘ Lehrbuch,” Jena, 1897, 2te Aufl., S. 382-392, 
Hi the subject is very fully treated and many more references to the literature will be 
ound. 

6 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1892, Bd. xxix. 8. 212. 

7 Op. cit., 1894. 

8 Fokker, Arch. f. d. ges. Physiol., Bonn, 1873, Bd. vii. S. 274. 

® Bunge, ‘‘ Lectures,” Wooldridge’s translation, p. 111. 

10 J. Forster, Zischr. f. Biol., Miinchen, 1873, Bd. ix. S. 369; and 1876, Bd. xii. S. 464 ; 
E. Voit, ibid., 1880, Bd. xvi. S. 55; Baginsky, Arch. f. Physiol., Leipzig, 1881, 8. 357 ; 
and Virchow’s Archiv, 1882, Bd. lxxxvii. S. 301; Seemann, Ztsehr. f. klin. Med., Berlin, 
1882, Bd. v. S. 1 and 152. 

" Riidel, Arch. f. exper. Path. u. Pharmakol., Leipzig, 1893, Bd. xxxiii. S. 90; O. 
Vierordt, Verhandl. d. xii. Cong. f. innere Med., Wiesbaden, 1893, S. 230. 

2 Chossat, Compt. rend. Acad. d. sc., Paris, 1842, tome xiv. p. 451; C. Voit, Ber. d. Vers. 
d. Naturf. z. Miinchen, 1877, S. 243; Art. ‘“‘Ernahrung” in Hermann’s ‘“‘ Handbuch,” 
Bd. vi. S. 379; the earlier literature of the subject will be found in this article. 


METABOLISM DURING INANITION. 887 


METABOLISM DURING INANITION. 


The problems of metabolism naturally subdivide themselves into 
those which concern the fate of the foodstuffs after they are absorbed 
and before they reach the tissues, and those which concern the fate 
of the stuffs which form the tissues, or which undergo changes within 
and by the agency of the tissues. The simplest condition of meta- 
bolism is therefore obtained when food is altogether withheld, as under 
these circumstances we have only to determine the changes which 
occur in the bodystuffs. On this account a very large amount of 
attention has been paid, both recently and previously, to the changes 
which occur in the tissues, as evidenced by the excreta during inanition 
in animals and man. 

There is one main fact which comes out in all experiments on 
inanition, namely, that in spite of the withholding of food, all the 
excretions continue, not certainly to their normal amount, but at least 
to a considerable extent. This is even the case with the feces 
which, in the absence of food, might be expected not to be formed. 
But, as a matter of fact, it is found that, during starvation, animals 
pass, if not every day, at least every two or three days, a fairly regular 
amount. This is composed of mucus and of inspissated digestive juices, 
a good deal altered in their composition, together with epithelial cells 
and other débris. Urine is also regularly passed during a period of 
inanition. The secretion of the skin is given off; carbon dioxide and 
water continue to be exhaled from the lungs; and in consequence of all 
these losses from the body the animal gradually loses in weight. 
The greatest proportionate amount lost is always during the first day 
of a fasting period. This is owing to the fact that the products of 
metabolism of the proteid food previously absorbed and that still within 
the alimentary canal are then got rid of. But after the first day or two 
it is found that the loss in weight is pretty definite, and nearly regular 
from day to day, and that fairly regular, or at least only gradually 
decreasing, amounts of the various excreta are lost daily. Thus Voit,? 
experimenting upon a cat, found that about 4 to 5 grms. of urea were 
passed each day, representing a loss of tissue of from 25 to 30 grms., 
and this with great regularity until the twelfth day, when there was a 
marked rise in the amount of urea eliminated. And similar results 
have been obtained both with other animals and men in a condition 
of inanition. 

The time at which this regular daily loss of nitrogen. begins, depends 
upon the previous condition of nourishment. Thus, in a dog experi- 
mented upon by Voit, three series of experiments were made, each 
extending over eight days of total deprivation of food. The animal had 
received before the first series, 2500 grms. of flesh daily; before the 
second, 1500 grms.; and before the third, a mixed diet with relatively 
little proteid. The results obtained are shown in the table on p. 
888. It will be seen that the regular loss begins at once in the third 
series, but not until the fifth day in the first series, in which the animal 
received most proteid during the previous period. The actual amount of 
proteid excreted per diem and per kilo. bodyweight was found by Voit 


1The amount of fat metabolised in the dog was found by Pettenkofer and Voit to be 
less during the first days than during the subsequent period. 
2 Hermann’s ‘‘ Handbuch,” Bd. vi. 


888 METABOLISM. 


Urea Excretion in Grammes per Diem. 


ees Series I. | Series II. Series III. 
1 60°1 26'5 13°8 
2 24°9 | 18°6 11°5 
3 19°1 15°7 10°2 
4 17°3 14°9 12°2 
5 12°3 14°8 12°1 
6 133 12°8 12°6 
7 12°5 12°9 11°3 
8 10°1 a 10°7 


to vary greatly with different dogs; small animals metabolise more 
proteid per kilo. than large; lean animals more than fat. Small dogs 
have a larger proportionate surface, and relatively a smaller amount of 
body-fat.t 

Many similar observations have been made on fasting men. One 
of these (Cetti) was under observation at different times and by 
different observers. His weight was about 57 kilos. The amount of 
urea excreted per diem, during the first ten days of fasting, was a little 
over 20 grms., equivalent to from 10 to 1lgrms. N. Another (younger) 
man, weighing about 60 kilos., was also found by I. Munk to excrete per 
diem, during the first ten days of fasting, about 11 grms. N, representing 
an average loss per diem of about 70 grms. proteid. In these cases there 
was but little body-fat. In other individuals, in which there was abund- 
ance of body-fat, the N excreted has been found to be much less. Thus 
Succi (weight 63 kilos. at beginning, 52 kilos. at end of period) was found 
by Luciani, during a thirty days’ fast, to excrete on the tenth day 
6-7 grms.; on the twentieth, 43 grms.; and on the last day 3-2 grms. N ; 
and Jacques (62 kilos.), observed by Noél Paton and Stockman, gave an 
average daily loss of 5°29 N. Praussnitz determined the amount of N 
excreted by ten persons during the second day of fasting, and found the 
average, for a man weighing about 70 kilos., to be 15°7 grms., equivalent 
to a loss of 90 grms. proteid per diem, or about 1:2 grms. per kilo. 
body weight. This may therefore be regarded as representing the 
amount which it isabsolutely necessary to supply in the food, for the 
maintenance of nitrogenous equilibrium. 


In herbivora there may be an actual increase in the nitrogenous excreta 
at the beginning of a starvation period, instead of a diminution; due to 
the fact that, under these circumstances, such animals, being reduced to living 
upon their tissues, become practically carnivorous. As in carnivora, such 
increase may become greater towards the end of inanition, in consequence of 


the exhaustion of the fat of the body, and an increased destruction of the tissue 
proteids.? 


Now, the amount of urea in the urine during a fasting period of not 
too long duration is probably a definite measure of the necessary de- 
struction of tissue proteid which goes on within the body, and it may 
therefore be taken as a result of such experiments, that the amount of 
this metabolism is fairly constant. Such destruction occurs in spite of 


1 Rubner, Zischr. f. Biol., Miinchen, 1883, Bd. xix. S. 535. 


* Rubner, ibid., 1881, Bd. xvii. S. 214; Heymans, Bull. Acad. roy. d. sc. de Bely., 
Bruxelles, 1896, p. 38. 


_ 4. 4 


METABOLISM DURING INANITION. 889 


the fact that there is still plenty of non-nitrogenous material (fat) able 
to be drawn upon. The sudden increase which is sometimes met with 
after a prolonged period of starvation is due no doubt to the fact that 
by this time the non-proteid materials of the body, which have been 
up to that time used for the production of energy by their oxidation, 
are now practically exhausted, and the whole energy and heat of the 
body must necessarily be derived from the tissues themselves ; since 
these are composed essentially of proteid, there is a considerable rise 
of proteid metabolism. 

The carbon dioxide exhaled from the lungs during starvation con- 
tinues to be given off in proportion to the weight of the body, to the 
work done, and in inverse proportion to the temperature of the environ- 
ment. In a man weighing 71 kilos., Pettenkofer and Voit found that 
during the first day of fasting 201°3 grms. C were given off by the respir- 
ation, and 5°8 grms. by the urine, in which also 12°5 grms. N was elimin- 
ated. This corresponded to a loss of 78 grms. proteid (570 grms. flesh) 
and 215 grms. fat. The same man was found by Pettenkofer and Voit 
to lose, when working on the first day of fasting, 75 grms. proteid (478 
erms. flesh) and 580 grms. fat. The amount of oxygen taken in in the 
two cases was 760 and 1072 grms. respectively, and the amount of water 
exhaled 889 and 1777 grms. Ranke found on the second day of fasting, 
in a fat subject weighing about 70 kilos.,8 grms. N and 5:7 germs. C in 
the urine, and 180-9 grms. C given off by the lungs; corresponding to 
50 grms. proteid (2 35. erms. flesh) and 204 grms. fat. 

For a considerable time, as a result of the oxidation of fat and body 
proteid, the temperature of a fasting animal is maintained to about its 
normal amount. Towards the end, however, of starvation, the temperature 
begins to sink, and finally rapidly falls, the meaning of this being that 
the animal has now practically exhausted all the nutriment which it 
can take from the tissues, and that the amount of oxidation has become 
reduced, so that the temperature is no longer capable of being main- 
tained at normal. The change is also, in part, doubtless due to the 
fact that the heat regulating functions of the nervous system are 
beginning to break down in consequence of the deficiency of nutriment. 
It has been suggested that an animal dying of starvation practically 
dies of cold; and it is undoubtedly true that the life of a starved animal 
can be prolonged considerably by the employment of artificial warmth, 
since this diminishes the amount of oxidation necessary for maintaining 
the animal heat, and thus economises the energy-producing substances 
within the body; but it is, of course, not possible for the artificial 
warming of an animal to prolong life to any great extent under 
circumstances of complete deprivation of food. 

Numerous experiments have been made to determine the amount of 
loss of the several organs and tissues of the body which have occurred 
during starvation, and also the relative composition of such tissues and 
organs as compared with those of a well-nourished animal. All such 
experiments tend to show that the most essential organs of the body, 
such as the heart and nervous system, live during a period of starvation 
at the expense of the other tissues.1 


1 Bidder and Schmidt, ‘‘ Verdauungssifte u. Stoffwechsel,” 1852; Bischoff and Voit, 
*“Die Gesetze der Ernihrung des Fleischfressers, ” 1860; Pettenkofer and Voit, Zéschr. 
f- Biol., Miinchen, Bde. ii. and v. de Ranke, “* Die Ernahrung des Menschen, ” 1876 ; Voit, 
“ Ernabrung,” Hermann’s ‘* Handbuch,” 1881, Bd. vi. 


890 METABOLISM. 


The first substances to disappear, as may well be supposed, are those which 
are least essential to the maintenance of life, and we find accordingly that the 
adipose tissue first begins to lose weight. Finally, at the end of starvation, 
90 per cent., or more, of the fats of the body (except the fatty substances 
which are found in the nervous system) have disappeared. At the same time 
the glycogen which may” have been stored in the liver and muscles also 
begins to disappear; but it is a long while, in some animals, before the last 
traces of it are used up, especially the glycogen of muscle. Certain of the 
organs especially become diminished in weight. Among these the first to 
show a falling off are the spleen and the glandular organs, especially those 
concerned in digestion. Since there is very little secretion going on, these are 
not called upon to exercise their normal functions. Next follows marked 
diminution in the amount of the muscular substance, and this it is, no doubt, 
which accounts for the muscular weakness which manifests itself. When all 
the less essential organs have contributed as much as appears possible to the 
maintenance of the normal condition of the blood, in order that it may suffi- 
ciently nourish the most essential tissues, the latter, namely, the heart and 
those of the nervous system, might next be expected to contribute their 
quota. Apparently, as soon as this call is made, they fail to respond to it, 
and the result is that death speedily supervenes. 

Voit gives the following percentage loss for the several tissues and organs 
in a cat killed after thirteen days’ deprivation of food :— 


In 100 Parts of In 100 Parts of 


Fresh Organs. Dry Organs. 

Adipose tissue : : ; siera - 
Spleen . ; : ; : wy Od, 63 
Liver. . : : 3 DE 57 
Testes. : ‘ : : gee aes 
Muscles . : ; s : P| 30 
Blood. ; ; : : flag 18 
Kidneys. : : : : SOG 21 
Integument . : R L ui | ie 
Lungs . : L i : mas bc) 19 
Intestines : : é : Hake 

Pancreas ‘ : : : hale 

Bones. ‘ ; : : sy A 

Heart . ‘ ‘ : , . hee sae 
Central nervous system . : ot vnaphek 0 


Tominaga! has determined (by Kjehldal’s method) the amount of N lost 
from the several organs during a prolonged starvation period in rats and 
rabbits, as follows :— 


| 

| Organ. Rat. Rabbit. 

| Spleen . : : ; : : 98°48 67°06 
Stomach and intestines . ; f 59°47 26°80 

| Muscles . : : : : . 35°98 18°59 

| Heart . : : : : ; 18°01 Die: 

| Brain . ' ; : 4 A 11°79 29°13 

| Liver . 2 i é F - 9°69 57°60 
Kidneys. : . : 5 : 3°48 24°80 

| 


The discrepancies in these results, both as compared with one another and 
as compared with the loss in the dry organs as determined by Voit, are so con- 
siderable, that they cannot be accepted without confirmation. 


' Centraibl. f. Physiol., Leipzig u. Wien, 1893, Bd. vii. S. 381. 


NUTRITION WITH A PURELY PROTEID DIET. 891 


The literature of the subject, since the article by Voit in Hermann’s 
“Handbuch ” (1881), will be found mainly in the memoirs noted below.* 


NUTRITION WITH A PURELY PROTEID DIET. 


Under the circumstances we have been considering, namely, complete 
deprivation of food, the nitrogen excreted must come from the nitrogen 
of the tissues, and it might be supposed that if we supply a starving 
animal with food containing the exact amount of nitrogen (in the form 
of proteid) which it is losing, we should be able to entirely prevent such 
waste of the tissues, and that any loss then occurring would arise solely 
from non-proteid substances. This, however, is not the case. For if 
this experiment is performed, it is found that the animal loses more 
nitrogen than we give it. The whole of the nitrogen of the added 
proteid appears in the urine as urea, and in addition there is a certain 
amount, although not as much as during complete starvation, of tissue 
nitrogen still present in the urine. In order to keep up nitrogenous 
equilibrium, Voit found that it was necessary to give two and a half 
times as much proteid as the animal had metabolised during fasting. 
This result, which is at first sight somewhat unexpected, is due to the 
fact that the ingestion of proteid food directly excites the tissues to 
increased metabolic activity, so that tissue proteid itself still becomes 
split up and oxidised. 

How and why the activity of the living tissues is thus stimulated 
by increased proteid pabulum is a problem as to which we are entirely 
in the dark. Non-proteid substances do not produce this effect. On the 
contrary, the giving of gelatin, carbohydrates, and fat has, as we have 
seen, a sparing effect upon proteid metabolism, and tends to diminish 
the amount of tissue proteid which is becoming broken down. This is 
also shown very conclusively in Voit’s experiments on dogs which had 
been kept in a condition of N-equilibrium with proteid food. The con- 
dition of N-equilibrium could be produced with a far smaller amount 
of proteid, provided that for the amount removed an adequate quantity 
of fat or carbohydrate was added to the diet.? 

If to a starving animal, instead of what would appear to be just a 
sufficient amount of proteid, an excess be given, a point is at length 
reached at which the building-up process exceeds the breaking-down, 
and the tissues, and therefore the body generally, gain in weight. 
This increase in body weight, due to the laying on of tissue, proceeds 
to a certain point with any constant amount of added proteid, until 
a balance between the N laid on and the N lost is struck, when a 
condition of N-equilibrium is again obtained. A further increase of 


1[mciani, ‘‘Fisiol. d. digiuno,” German translation, ‘‘Das Hunger,” 1889; Richet, 
‘‘T/inanition,” Travaux, 1893, tome ii.; Tucsek, Centralbl. f. d. med. Wissensch., Berlin, 1885, 
S. 69 ; Lehmann, Miiller, Senator, Zuntz, I. Munk, and others, Berl. klin. Wchuschr., 1887, 
S. 425; and Virchow’s Archiv, 1893, Bd. cxxxi., Suppl.-Heft ; I. Munk, Centralbl. f. d. 
med. Wissensch., Berlin, 1889, S. 833; Noél Paton and Stockman, Proc. Roy. Soc. Edin., 
1889, p. 121; Praussnitz, Miinchen. med. Wehnschr., 1891, No. 18; and Ztschr. f. Biol., 
Miinchen, 1893, Bd. xi. S. 151; R. May, ibid., 1893, Bd. xii. S. 29; I. Munk, dreh. f. 
d. ges. Physiol., Bonn, 1894, Bd. lviii. S. 309; Johansson, Landgren, Sondén and 
Tigerstedt, Skandin. Arch. f. Physiol., Leipzig, 1896, Bd. vii. S. 29; C. Voit, Zschr. 
f. Biol., Miinchen, 1894, Bd. xxx. S. 510 (comparison of weight of organs in well-nourished 
and starved dogs). See also on this subject, Lukjanow, Zéschr. f. physiol. Chem., 
Strassburg, 1889, Bd. xiii. S. 339. 

2 Voit, op. cit. 


892 METABOLISM. 


proteid food will now again produce an increase of tissue and of body 
weight, until again a condition of N-equilibrium is established. And 
this may apparently be carried up to the limit of the power of digestion 
of the animal for proteid food, so that ultimately fifteen times as much 
proteid may be metabolised as in the condition of inanition.! On the 
other hand, diminution of the amount of proteid food tends in the same 
way to gradually establish N-equilibrium on a lower level, and with a 
diminished body weight; the animal losing flesh until such equilibrium 
becomes established, and then maintaining itself, provided the N ingested 
be constant, at a constant but lower level of N-equilibrium. In short, 
“N-equilibrium is possible with the most different amounts of proteid 
in the food.” 2 

The fact that the amount of urea excreted is directly dependent 
upon the amount of proteid ingested, is well illustrated by the 
following observations of Voit upon a dog fed on lean meat; the 
numbers are grms, :— 


Meat perdiem . 300 600 900 1200 1500 1800 2000 2500 
Urea perdiem . 32 49 - 68 88. 106. 128. tae ie 


About 80-85 per cent. of the ingested proteid is usually oxidated 
and eliminated, and only about 15-20 per cent. is laid on. 


ON THE BUILDING-UP AND BREAKING-DOWN OF THE BODYSTUFFS. 


The food of animals consists, besides water and a certain amount of 
inorganic salts, of organic constituents, nitrogenous (some of which must 
be proteid) and non-nitrogenous. The food of the higher plants, on 
the other hand, consists normally of inorganic materials, some of which 
must be nitrogenous; and, as has been long recognised, plants have the 
power of building up from these materials complex organic substances, 
such as proteids, carbohydrates, and fats, whereas animals have not this 
power; the materials built up by plants serving as the food of animals. 
Hence arose the belief that it was an essential difference between the 
plant and animal organisation, that the one possessed extensive 
powers of effecting syntheses, whereas the other had practically no 
powers of synthesis, but must receive its materials already synthetised, 
either directly from plants or indirectly from plants through the bodies 
of other animals, such materials being subsequently broken down into 
simpler materials, which, after being oxidised within the tissues, are got 
rid of in such simple forms as urea, water, carbon dioxide, and salts. 

These views have undergone considerable modification of late years, 
since we are now familiar with numerous instances of syntheses oceur- 
ring in animals. The first well-established case of the kind was 
determined by Wohler in 1824. Wohler found that when benzoic acid 
is taken with the food, it appears as hippuric acid in the urine. Now, 
hippuric acid is formed synthetically from benzoic acid and glycine. 


'C. Voit, Hermann’s ‘‘Handbuch,” Bd. vi. S. 105. Voit’s dog, weighing 35 kilos., 
was able to maintain N-equilibrium with as little as 500 and as much as 2500 grms. 
flesh, containing 548 grms. dry proteid. With larger amounts than this, digestion was 
interfered with. The same fact is still more strikingly shown by the experiments of 
Pfliiger, who kept a large dog in a condition of nitrogenous equilibrium on an almost 
exclusively proteid diet. A man weighing 70 kilos, is, as a rule, unable to digest more 
than 1500 grms. of lean meat per diem. 

(Ce Wait, Uae, Chin, Ss Tan 


BUILDING-UP AND BREAKING-DOWWN BODYSTUFHFS. 893 


It is produced when these two substances are allowed to act upon one 
another at a high temperature, and under pressure, as when they are 
heated together for some hours in a glass tube to a temperature of 160° 
C.,or more simply by heating monochloracetic acid with benzamide :— 


0,H,CO.NH,+CH,Cl.COOH =(C,H,CO)NH.CH,.COOH+HCl 


(benzamide) (monochloracetic acid) (hippuric acid) 


This synthesis of hippuric acid in vitro was speedily followed by that of 
urea (Wohler, 1828). 

The synthesis of hippuric acid was proved by Bunge and Schmiede- 
berg to occur in dogs exclusively in the kidney, and may be produced 
even at the temperature of the room, by passing oxygenated blood 
containing benzoic acid, or a benzoate, and glycine through the blood 
vessels of the organ, or even by allowing such blood to stand for a 
while in contact with the minced kidney of a fresh-killed animal. 
When, however, the kidney cells are destroyed, as by being pounded with 
sand in a mortar, no hippuric acid is produced.’ If benzoic acid be 
given by the mouth, hippuric acid appears in the urine; the glycine for 
the synthesis is furnished by the tissues. If the kidneys are previously 
extirpated, no hippuric acid is found in any of the organs after the 
exhibition of benzoic acid; but if the ureters are merely ligatured, 
hippuric acid is found in abundance. 

In frogs and rabbits the synthesis of hippuric acid is not confined to the 
kidneys, but is found to occur after the extirpation of these organs.’ 

Other syntheses besides that of hippuric acid, which are known to 
occur in the animal body, are that of urea in the liver, from ammonium 
carbonate and ammonium carbamate ; that of uric acid in the bird’s liver, 
also from ammonia compounds; that of glycogen, from glucose in the 
liver, and also in muscles and in many other tissues; that of proteids, 
from peptones in the mucous membrane of the alimentary canal; that of 
fats, from fatty acids and glycerin in the intestinal mucous membrane ; 
that of fats from carbohydrates, or from the elements of the broken-down 
carbohydrate molecule; and also, in all probability, that of fats from the 
non-nitrogenous moiety of the broken-down proteid molecule. It is clear 
from these instances that the importance of syntheses in the animal 
economy cannot be overrated, and although the most striking feature in 
animal metabolism is the breaking down of complex substances into 
others of more simple form, yet even in the case of these broken-down 
products there is frequently a subsequent synthesis before they are got 
rid of from the body. Instances of this occur in the case of several urinary 
products, such as hippuric acid, urea, and uric acid.? 

As Bunge® remarks: “There are two reasons why these synthetic 
processes in the animal body have excited the interest of physio- 
logists and chemists. In the first place, they were in contradiction 
to the long dominant doctrine of Liebig, as to the contrast be- 
tween the metabolic processes in plants and animals;* and, in the 


1 Bunge and Schmiedeberg, Arch. f. exper. Path. u. Pharmakol., Leipzig, 1876, Bd. vi. 
S. 233 ; Hoffman, ibid., 1877, Bd. vii. S. 239 ; Kochs, Arch. f. d. ges. Physiol., Bonn, 1879, 
Bd. xx. S. 64; Salomon., Zischr. f. physiol. Chem., Strassburg, Bd. iii. 8. 365. 

2 On the importance of synthetic processes in animal metabolism, see Pfliiger, Arch. f. d. 
ges. Physiol., Bonn, 1888, Bd. xlii. 8. 144. 3“ Tehrbuch,” 1894, S. 288. 

* Nevertheless, the main distinction propounded by Liebig, that most plants are able 
to obtain their nitrogen, and to build it up into proteid from inorganic materials, whereas 
animals do not possess this power, still holds good. 


894 METABOLISM. 


second place, the methods of synthesis in animal (and vegetable) 
organisms are still an unsolved problem, in spite of the fact that 
it is the rapid progress in our knowledge of the syntheses of organic 
combinations which constitutes the greatest triumph of modern: 
chemistry. Chemists are already able artificially to build up atom for 
atom out of their elements a series of organic compounds, some of a very 
complicated nature. We no longer doubt that all the rest, even the 
most complex, will be thus produced. Nevertheless the processes 
employed in no way represent the synthetic processes of the living cell, 
for all artificial syntheses can only be achieved by the application of 
forces and agents which can never play a part in vital processes, such as 
extreme pressure, high temperature, concentrated mineral acids, and free 
chlorine—agents which are immediately fatal to any living cell.” 

It must nevertheless be admitted, in spite of the numerous instances 
of syntheses of organic compounds which have accumulated of late years, 
that, so far as the formation of bioplasm is concerned, the only material 
from which the animal organism is capable of forming it is proteid, and 
this proteid must be present as such in the food. No doubt the ultimate 
change of the circulatory or blood proteids to the proteid of bioplasm must 
depend upon a special synthesis, but we are necessarily completely ignor- 
ant as to the manner in which such synthesis occurs, since we are ignorant 
of the actual chemical constitution of both living tissue and dead proteid. 

With respect to the breaking-down of the bodystuffs in the process 
of metabolism, there are reasons for believing that this consists of two 
phases, namely, a splitting of the complex molecules into simpler mole- 
cules, and an oxidation of some or all of the simpler substances thus 
arising. It is probable that in the metabolism of proteid these two 
phases usually, if not invariably, occur at different times, and even in 
different places in the body; for example, the materials derived from 
the splitting up of the metabolised proteids of muscle do not all leave 
the muscle in a fully oxidated condition, but are, in part at least, in 
the form of oxidisable substances, such as lactic acid. Doubtless, in 
the formation of the ultimate products, oxidation is the prominent 
feature, for these products, in the form in which they leave the body, are, 
as compared with the materials that enter the tissues, unquestionably 
in a condition of oxidation, in some cases of complete oxidation. There 
is, however, no distinct evidence that the process of splitting of the 
complex molecules is necessarily immediately combined with that of 
oxidation. On the other hand, there is reason to think that such 
splitting may occur without immediate oxidation; for example, the 
splitting of proteids, which are taken in the food, into urea and non- 
nitrogenous substances. For, in a dog fed with proteid, the urea was 
found by Feder to make its appearance in the urine within fourteen 
hours after feeding, whereas the removal of the remainder of the proteid 
molecule in the form of carbon dioxide and water did not occur for 
twenty-four hours after, so that the splitting of the proteid molecule 
must have occurred at one time, and its complete oxidation at another. 

It is found that any conditions which tend to diminish the normal 
oxidations of the body generally, or of the individual tissues (such as 
the ingestion of prussic acid or the cutting off or diminution of the 
arterial supply to an organ), cause such substances as lactic acid and 
dextrose, which are probably products of proteid and carbohydrate 

1C. Voit, Zschr. f. Biol., Miinchen, 1891-2, Bd. xxviii. S. 292. 


METABOLIC ACTIVITY OF TISSUES AND ORGANS. 895 


metabolism respectively, to appear in larger amount than usual in the 
blood, and to become excreted in the urine.! 


RELATIVE METABOLIC ACTIVITY OF THE TISSUES AND ORGANS. 


Before we trace the fate of the foodstuffs in the body, it is 
important we should have an idea of the relative metabolic activity of 
the tissues, since all essential changes which contribute to the pro- 
duction of the energy of the body occur within the tissues. 

It was at one time believed that the blood was the seat of 
important oxidation processes; but whilst it cannot be denied that a 
certain amount of oxidation may occur in the blood, as shown by the 
rapid diminution in the oxygen of the oxyhemoglobin, on allowing blood 
to stand in a closed vessel,” it is certain that by far the greatest part of 
the oxidations in the body occurs in the tissues, and especially in the 
muscles. It was found by Pfliiger, that frogs whose blood had been 
wholly replaced by salt solution took in just as much oxygen, and gave 
off just as much CO,, as normal animals. Moreover, Pembrey and 
Giirber found hardly any alteration in the oxidation processes in rabbits 
which had been deprived of a large proportion of their blood.+ 

Placing the tissues in order of relative activity, the muscles must 
take the first place; next to these the secreting glands; and next to 
these the tissues of the nervous system, especially the grey matter. 
Last in the scale come the skeletal tissues, which, performing as they 
do a passive function, may be assumed to exhibit comparatively little 
metabolic activity. With regard to the most active of the tissues, 
namely, the muscles and the cells of secreting glands, we may note, in 
passing, that their chemical composition is by no means identical. 
The most prominent organic material in muscular tissue is native 
proteid of the globulin class, whereas the most prominent organic 
materials in the living tissue of gland cells are nucleo-proteids. This 
distinction, though frequently ignored, is one of considerable import- 
ance, for the nucleo-proteids have a constitution more complex than 
that of proteids, consisting as they do of a combination of proteid with 
phosphorus-containing substances, which yield as products of decomposi- 
tion, xanthine bases, nucleins, paranucleins, and phosphoric acid, and 
some of them, at all events, a carbohydrate (see pp. 66, 67). 

There can be very little doubt that the greater part of the oxidation 
of the body occurs in the muscles. The formation of heat can, in fact, 
be shown to be mainly due to the chemical activity of the muscles, an 
activity called into play under the influence of the nervous system; 


1 Zillesen, Zischr. f. physiol. Chem., Strassburg, 1891, Bd. xv. S. 387; Araki, <bid., 
1891—4, Bde. xv., xvi., xvii., xix. 

2 The disappearance of the oxygen of oxyhemoglobin which occurs in blood on standing, 
has been ascribed to the presence of hypothetical substances, to which the term ‘‘ reducing 
substances” has been applied. No chemical substances having such a reducing power have, 
however, been either isolated from blood or chemically investigated. Moreover, the reduc- 
tion of oxyhemoglobin in blood on standing, may be due to its oxygen being removed 
by the bioplasm both of the white corpuscles and of putrefactive bacteria, which rapidly 
begin to appear and multiply in drawn blood. Reduction even occurs with solutions of 
pure crystallized oxyhemoglobin hermetically sealed in glass tubes. 

8 Arch. f. d. ges. Physiol., Bonn, Bd. x. 8. 251; see also @rtmann, ibid., 1877, Bd. xv. 
8. 382. 

4 Journ. Physiol., Cambridge and London, 1894, vol. xv. p. 449. 

5 In connection with this question, the possibility must not be forgotten that even 
ordinary proteids may have a carbohydrate nucleus in their molecule (cf. p. 64). 


896 METABOLISM. 


and the greater the amount of muscular activity the greater the amount 
of oxidised materials in the form of carbonic acid and water that are 
formed and got rid of from the body. It is probable that the oxidation 
processes which occur in gland cells are by no means so active, for 
although a gland when stimulated to activity receives a larger amount 
of oxygenated blood, yet a considerable amount of the oxygen of that 
blood simply passes through the capillaries without being absorbed, so 
much so, in fact, that, as noted by Bernard, the blood of the veins of the 
salivary glands during stimulation of their cranial nerves flows almost 
as bright red as that of an artery. And in confirmation of this we find 
that the largest gland in the body, the liver, is supplied with a relatively 
small amount of arterial blood, and that almost the whole of its 
metabolic activity is carried on with blood which already has passed 
through the intestinal capillaries, and which has thereby been deprived 
of a large part of its oxygen. Further, it was noted by Ludwig that the 
saliva flowing from the duct of the submaxillary gland contains more 
oxygen, than is dissolved in the plasma of the arterial blood, an 
indication that the cells of the salivary glands cannot be greedy of 
oxygen since they pass oxygen out along with the secretion rather than 
retaining it for the formation of carbon dioxide and water. The 
salivary glands, moreover, have been shown by the recent careful 
observations of Bayliss and Hill not to produce any appreciable amount 
of heat; and although it is stated that the blood flowing through the 
liver is the warmest blood in the body,? and warmer than that flowing 
through the muscles, it must be borne in mind that it is almost 
impossible to measure exactly the normal temperature of the blood 
flowing from the muscles, because the operation necessary for observing 
the temperature of such blood would tend to expose it to loss of heat.* 


In conformity with the conclusion that the muscles are the organs which 
possess by far the greatest amount of metabolic activity, it has been estimated 
that the muscular tissues contain about one-fourth of the whole blood of the 
body. The liver, which has important special functions to perform in 
metabolism—functions which are, however, probably in large measure inde- 
pendent of oxidation—contains another fourth of the blood, one-fourth is 
employed in keeping full the larger arteries and veins, and all the rest of the 
body put together has for its capillary supply only the remaining fourth. It 
is clear, then, that in all observations and experiments upon the metabolism 
of the body, the metabolism of the muscles must occupy a prominent place. 


NITROGENOUS METABOLISM IN THE TISSUES. 


Of the proteids of the body Voit distinguishes two kinds—(1) Those 
which form an integral part of the living substance or bioplasm, and (2) 
those which occur in the tissue juice and in contact with the bioplasm, 
but which are not to be regarded as forming an integral part of that 
substance itself. To this latter kind he has given the name of “circu- 


1 Journ. Physiol., Cambridge and London, 1894, vol. xvi. p. 351. Previously to this 
work, it had been accepted, on the authority of Ludwig and others, that the secretion of 
saliva is accompanied by a marked production of heat within the submaxillary gland. 

2 See p. 826. Waymouth Reid was unable to find any effect on the temperature of the 
liver as the result of stimulating the splanchnic and vagi nerves (‘‘ Proc. Phys. Soc.,” 
1895, p. xxxi., in Journ. Physiol., Cambridge and London, vol. xviii. ). 

3 Tn his experiments upon the gaseous exchange in blood perfused through “ surviving” 
mammalian muscle, v. Frey found that the blood leaving the muscle was slightly warmer 
than that entering it (d7rch. f. Physiol., Leipzig, 1885, p. 559). 


* 


NITROGENOUS METABOLISM IN THE TISSUES. 897 


lating proteid,” while the proteid which is assumed to actually form the 


living substance of the tissues is termed by Voit, Organeiweiss, which 
may be rendered in English by “organ- or tissue-proteid.”! If the 
term “ circulating proteid” be used to include the proteids of the blood 
and lymph as well as those which occur in the actual interstices, if 
any, of the bioplasm, no exception can be taken to it, but if it 
is used, as has been sometimes done by Voit, in a restricted sense, 
merely to indicate proteid material which is interpolated amongst the 
molecules of the proteid forming the bioplasm, without itself actually con- 
stituting part of that substance, it must be admitted with Pfliiger? that 
such employment of the term can only be misleading. Using, however, 
the term circulating or unorganised proteid in the wider sense, there are 
still two possibilities open as to the manner in which the proteids of the 
body undergo metabolic changes—(1) We may assume that the circu- 
lating proteid, reaching the tissues and becoming imbibed by them, 
must be completely incorporated and built up into them before it is 
split up and oxidised; or (2) it is open to us to suppose that the 
unorganised proteid may be split up and oxidised outside the actual 
molecules of the organised proteid of the living substance, but as a 
consequence of the action of that substance. In the one case we may 
suppose it to produce a direct formation or building up of bioplasm—a 
transformation, in fact, of unorganised into organised proteid; in the 
other case, as undergoing contact changes by the action of the bioplasm, 
much in the same way as contact changes are brought about by organised 
ferments. . 

One reason for believing that the circulating proteid only becomes 
in part built up into the material of the bioplasm, is derived from the 
following observation (Voit). If, to an animal kept upon a diet con- 
sisting of non-proteid food (fat), gelatin is given in an amount sufficient 
to replace a caloric equivalent of such non-proteid material, it is found 
that, reckoning for the amount of nitrogen due to the metabolised 
gelatin, which always appears in full as urea, there is less nitrogen given 
off from the body than before ; that is to say, there is less tissue substance 
broken down. But in the total absence of nitrogenous food there is a 
definite amount of body proteid metabolised; and since, when gelatin 
is given, it is metabolised instead of part of this proteid, although it 
cannot itself be built up into tissue substance (p. 878), it must be 
assumed that the gelatin has taken the place of proteid which, although 
in such intimate: contact with the bioplasm as to become metabolised 
under its influence, did not actually form bioplasm. It may further 
be argued that the rapidity with which metabolic changes in proteids 
occur within the body, and the large amount of such metabolism, when 
excess of proteid is taken as food, render it improbable that all meta- 
morphosed proteid has been built up to form bioplasm. 


1¢, Voit, ‘‘ Die Ernahrung,” Hermann’s ‘‘ Handbuch,” Bd. vi. S. 301. The terms 
‘‘organised”” and ‘‘ unorganised” proteid are preferable to ‘‘tissue-” and ‘‘ circulating-” 
proteid, which have been used at different times in different senses. In earlier publications 
(Ztschr. f. Biol., Miimchen, 1874, Bd. x.) Voit included the proteids of blood plasma under 
the designation ‘‘ Organeiweiss,’’ founding this view upon the fact that, as the experiments 
of Tschiriew (Ber. d. k. stichs. Gesellsch. d. Wissensch., 1874, S. 411) and Forster (Sitzwngsb. 
d. k.-bayer. Akad. d. Wissensch. zu Miinchen, 1875, S. 206) seemed to show, transfusion 
of blood does not increase the proteid metabolism of the body. Pfliiger, however (doc. cit., 
infra, pp. 362 et seg.) has shown that the results of Tschiriew and Forster are capable of 
a diametrically opposite interpretation. 

2 Arch. f. d. ges. Physiol., Bonn, 1893, Bd. liv. S. 333. 


VOL. 1.—57 


898 METABOLISM. 


Voit has drawn a much sharper distinction between the organised and 
unorganised (tissue and circulating) proteid than that above indicated. He 
denies that tissue proteid can as such undergo metabolism, even in inanition. 
According to his view, it must first be dissolved up and take the form of 
circulating proteid, and be carried in this form to other tissues (e.g. from the 
muscles to the heart and nervous system), to be metabolised as circulating 
proteid in these.t This view is, however, difficult to reconcile with the 
supposition that there is no chemical difference between the two forms of 
proteid,” for if there is no such difference, it is not clear why the proteid 
should not become metabolised in the tissues themselves, but should need to 
be conveyed outside them before undergoing metabolic changes. Moreover, it 
is entirely inconsistent with the experiments of Oertmann and Pifliiger, of 
Pembrey and Giirber, and of Schéndorff (with Pfliiger), which will be subse- 
quently referred to. 

The arguments and experiments by which Voit has endeavoured to support 
his position are, however, quite insufficient to carry conviction, and it must be 
regarded as having been rendered completely untenable by the experiments 
and criticisms of Pfliiger.2 A view exactly the contrary to that of Voit was 
taken by Liebig, and has been maintained by Hoppe-Seyler, and in a some- 
what qualified form by Pfliiger. According to this view, it is only organised 
proteid which can undergo metabolic changes—never unorganised. Unorgan- 
ised proteid must therefore first be converted into organised before it is 
capable of metabolism ; in other words, tissue bioplasm must be built up out of 
circulating proteids before these last, which then of course have become 
tissue proteids, can be broken down and oxidised. It is therefore denied that 
any metabolism of proteids can occur outside the actual molecules of the living 
substance—that, in short, there can be any contact action. It has, however, 
been shown in the case of yeast, that chemical action may take place outside 
the living cells, although under their direct agency, so that the possibility of 
metabolic changes occurring under the influence of, but outside, the actual 
molecules of the protoplasm of cells cannot be denied. Moreover, it is not 
probable that the non-proteid materials (fat, carbohydrate, gelatin) of the 
food become after assimilation built up into bioplasm, and although they are 
undoubtedly taken into cell protoplasm they can hardly be regarded as 
forming constituent parts of the molecules of its bioplasm. In this sense, 
therefore, they are outside, although in contact with, the bioplasm of the 
tissues.; nevertheless they are found to undergo metabolic changes under the 
influence of that substance. It may, of course, be argued that they also are 
really built up into the living proteid molecule, and must be so before they 
can become metabolised, but there is absolutely no evidence that this is the 
case, or that fat or carbohydrate are necessary constituents of bioplasm. 

The fat drops which we see embedded in the protoplasm of cells, are 
certainly not constituent parts of the bioplasm, although under its influence 
they undergo physical and chemical changes, and the same is the case with 
the glycogen clumps which can be seen in the liver cells, to say nothing of 
the starch, aleuron, and fat granules of vegetable cells. The phenomenon of 
contact change is in short too universal to be denied. Since this is so, the 
most reasonable view to be taken of the matter appears to be one which 
supposes that metabolism may occur both as a splitting-up and oxidation of 
the molecules of living tissue or bioplasm, and as a splitting-up and oxidation 


1 Loc. cit., S. 308. 

2«Tch will also nicht damit einen chemischen Unterschied bezeichnen, sondern 
zunichst nur einen Unterschied in dem Orte an dem es sich befindet. . . . Ein und dasselbe 
Molekiil Eiweiss kann in einem bestimmten Momente Eiweiss des Blutplasmas, in einem 
nichsten Eiweiss der Ernahrungsflussigkeit, in einem anderen Eiweiss der Lymphe oder 
auch Organeiweiss sein ” (doc. cit., S. 301). 

3 Loc. cit. 


NITROGENOUS METABOLISM IN THE TISSUES. 899 


both of unorganised proteid and of non-proteid materials outside but in 
contact with the molecules of bioplasm. Such a view, which is in a sense 
intermediate between the extreme opinions advocated by Voit and Pfliiger 
respectively, is consistent with all the known facts, and is more readily applic- 
able to the phenomena, both of animal and vegetable metabolism, than the 
exclusive acceptance of either of those opinions. 

Whether directly or indirectly, tissue proteid normally undergoes meta- 
bolism to the extent of about 1 per cent. of its substance per diem (Voit). 


The proteids of the food are converted by digestion into albumoses 
and peptones; ultimately, probably, entirely into peptones. They are, 
however, not absorbed as peptones, for no peptones are found in the 
blood or chyle leaving the intestines. It is clear, therefore, that the 
process of assimilation or the reconversion of peptones into proteids 
must occur during their absorption, that is to say, in the substance of 
the mucous membrane. It must not be forgotten, however, that a 
certain amount of the proteid of food may possibly, as occurs in vitro, 
be broken down beyond the stage of peptone into simpler nitrogenous 
bodies, such as the amido-acids; and these, if their formation really 
occurs to any extent in the intestinal tract, would be absorbed as such 
into the portal blood and conveyed by it to the liver. Now we know 
that the addition of amido-acids to the blood which is allowed to circu- , 
late through the liver, as well as their administration with the 
' food, causes an increase in the amount of urea in the blood after it has 
passed through that organ, and an increased excretion of urea by 
the kidneys. From this it may be assumed that any amido-acids 
absorbed are converted by a process of synthesis (possibly preceded by 
a previous more complete breaking-down, into ammonia compounds) into 
urea. If this process of formation of amido-acids occurs at all in natural 
digestion, it is obviously a change by which the proteids of the food 
would not be directly serviceable for the production of tissue; and in 
this sense such conversion of peptones into amido-acids may be looked 
upon as a direct waste of proteid food. It is extremely improbable that 
such a change occurs to any extent in the normal organism, nor has the 
presence of these substances to any marked degree been determined in 
the normal intestinal contents. Moreover, as Bunge remarks, there 
is not sufficient carbon in the proteid molecule to permit of all the 
nitrogen issuing as amido-acids.2 In any case, these bodies must 
probably be split up and oxidised into carbon dioxide and ammonia, and 
from these urea become formed by synthesis in the liver. We may 
therefore probably put aside as exceptional this mode of transformation 
of proteid into urea, and consider only the change which is undergone 
by the proteid which is actually assimilated. 


With regard to the agents in the mucous membrane which produce the 
assimilation of proteids, that is to say the conversion of peptones into proteids, 
there can be very little doubt that the columnar epithelium occupies the first 
place. It is, however, difficult to prove that the change, which is one of 
synthesis and dehydration, does actually occur in these cells. We have chiefly 
analogy to guide us in coming to this conclusion. It can be definitely proved 
that a synthesis of fat does occur in them; and it is therefore probable that 


1 Schultzen and Nencki, Zéschr. f. Biol., Miinchen, 1872, Bd. viii. S. 124 ; Salkowski, 
Ztschr. f. physiol. Chem., Strassburg, 1879, Bd. iv. S. 100; v. Knieriem, Zéschr. f. Biol., 
Miinchen, 1874, Bd. x. S. 279. 

2 « Lectures,” p. 320. 


goo METABOLISM. 


other syntheses which accompany assimilation, such as the formation of 
proteids from peptones, must also occur within them. Hofmeister! has 
suggested that the leucocytes may also take an important part in determining 
the assimilation of the foodstuffs. They are present in great abundance in 
the intestinal mucous membrane, and especially those parts of that membrane 
where absorption proceeds most extensively ; and they are also, it has been 
shown, greatly increased in number during the process of absorption. It is, 
however, difficult to obtain affirmative evidence upon this point, and since 
leucocytes elsewhere do not possess this power, it is improbable that they are 
the agents for such conversion in the intestine. 


After assimilation the proteids are absorbed by the blood vessels of 
the intestinal mucous membrane. The evidence for this has been 
already given in the article on “ Digestion and Absorption” (p. 433). 
If any proteids are taken up by the lacteals of the small intestine, they 
do not get into the thoracic duct,? but must be transferred to the blood 
vessels in passing through the mesenteric glands. At any rate we may 
assume that nearly the whole of the proteids are ultimately taken by the 
portal vein to the liver. The portal vein, therefore, contains the absorbed 
material derived from digestion and assimilation of proteid food; it 
must have, therefore (besides the ordinary constituents of blood plasma), 
an additional amount of serum albumin or of serum globulin, obtained by 
the transformation of the peptones into these materials ; also extractives 
of the meat or other forms of proteid diet (which are absorbed equally 
by the blood vessels of the intestine), and in addition any products 
of further decomposition of peptones, such as the amido-acids, the 
possibility of the presence of which we have already discussed. But it 
must be borne in mind that the blood flow through the portal system is 
so large and rapid, that one could hardly expect these substances to be 
absorbed into it in such a proportion that it would be possible to detect 
by chemical means any appreciable difference of composition between 
the blood of the portal vein and that of the system generally, nor are 
there any satisfactory analyses directly showing such difference. Never- 
theless there is a distinct physiological difference between the portal 
blood collected during absorption of food, and especially of proteid food, 
and the same blood collected during the intervals of digestion ; for it has 
been shown that in the former case such blood, on being passed through 
the liver, shows an increased amount of urea, whereas in the latter case 
such an increase is not noticed. It is certain, at any rate, that the 
products of absorption and assimilation of proteid foods are carried 
to the liver, and, having traced them to this organ, we have next to 
consider—(1) Whether they are stored at all within it; (2) whether 
they undergo any change in passing through it. 

Influence of the liver on proteid metabolism.— With regard to the 
possible storage of proteid in the liver, it is open to us to suppose 
that an excess of proteid material which is present in the portal blood 
as the result of the absorption of proteid food, might be temporarily 
taken up, at least in some measure, by the hepatic cells, and, after being 


4 1 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1884-7, Bde. xix. S. 1; xx. S. 295 xxii, 
. 306. 

* Asher and Barbera found, however, in a dog a marked rise both in the amount of 
chyle and of the nitrogen of the chyle (estimated by Kjeldahl’s method) during digestion 
of purely proteid food, given by a gastric fistula. The rise was greatest at the sixth hour 
after feeding, but there was a primary culmination at the second hour (Centralbl. f. 
Physiol., Leipzig u. Wien, 1897, Bd. xi. S. 403). 


INFLUENCE OF LIVER ON PROTEID METABOLISM. 901 


stored within them for a time, passed on into the hepatic blood to reach 
the general circulation. There is, however, no clear evidence that such 
storage takes place in the liver, or that if it does the stored proteid 
undergoes any change within the liver cells. 

When we examine the secretion of the liver, we find that it contains 
a considerable amount of nitrogenous organic material (bile salts), in- 
cluding a certain amount of sulphur in organic combination (taurine). 
These nitrogenous and sulphur-containing materials can only be derivea 
from proteids, and since they are formed in greater amount during absorp- 
tion of digested products than at other times, it might well be supposed 
that they may be formed, at least in part, from the absorbed products 
of proteid digestion. As against this conjecture, we cannot, however, 
fail to notice that the appearance of these nitrogenous and sulphur- 
containing materials in the bile salts is accompanied by a considerable 
amount of material in the form of bile pigments, which can only be 
derived from the hemoglobin of the red blood corpuscles; and since 
hemoglobin readily decomposes into hematin, which is probably the 
part directly converted, with elimination of iron, into bile pigment, and 
a proteid or proteids, it has been conjectured, and with some pro- 
bability, that the bile acids are actually derived from this proteid part 
of the broken-down hemoglobin molecule. The only direct evidence 
that we have of the breaking-down of blood corpuscles within the liver 
is derived from certain enumeration experiments, which appear to show 
that the number of blood corpuscles per cubic millimetre passing to the 
liver is greater than the number per cubic millimetre in the blood flow- 
ing from the liver. This by itself is not very strong evidence, but it 
becomes stronger when we remember that the blood flowing from the 
liver may be expected to contain /ess water than that which reaches 
the liver, since there has passed away from it the water of the bile 
and also a large amount of lymph. Moreover, the constant presence of 
lecithin and cholesterin in the bile may well be associated with the 
destruction of red blood corpuscles, which contain, relatively, consider- 
able amounts of these substances. 

While, therefore, the presence of the bile acids is a clear indication 
of the breaking-down of proteid in the liver, their presence does not 
necessarily indicate that such proteid is derived from the blood plasma, 
but it is,on the whole, more probable that it arises from the hemo- 
globin of blood corpuscles.” 

The storage of glycogen in the liver, under circumstances when if 
ean only be supposed to be formed from proteid, indicates another 
change which proteids may undergo in this organ. Such a formation 
of glycogen from proteid probably occurs hardly at all during absorption 
of a mixed meal, because the amount of carbohydrate absorbed from 
such a meal would be more than sufficient to account for the glycogen 
stored in the liver; but, in the absence of carbohydrate from the food, 
the proteids may become so split up that one portion of the proteid 
becomes converted into urea, or into materials which ultimately form 
urea, and the other portion, possibly by becoming first somewhat 
broken down and then again synthetised, into glycogen. 

A similar conjecture may be made with regard to the fat which is 


1 Nicolaides, Arch. de physiol. norm. et path., Paris, 1882, p. 531. 
2 According to Kunkel, taurine may be formed from proteids in the tissues generally, 
and carried to the liver, Ber. d. k. sdichs. Gesellsch. d. Wissensch., 1875. 


902 METABOLISM. 


found in the liver cells during absorption. We must, it is true, assume 
that when fat is present in the food, the fat which occurs in the liver 
cells during absorption is derived from it; for the absorbed fat, after 
passing through the columnar epithelium cells, in which there is little 
doubt that it undergoes metabolic changes, gets into the thoracic duct, 
and so into the blood, in which it is carried to the liver and elsewhere. 
Nevertheless, in the absence of fat from the food, any fat which is 
found within the liver cells may be supposed to be obtained from 
proteid after the splitting off of the elements of the urea molecule; 
but we must suppose a considerable breaking-down and a re- 
synthesis to occur. In both carbohydrate and fat formation we must 
recognise the possibility of the preliminary splitting of the proteid 
molecule occurring elsewhere than in the liver, although there is no 
reason to suppose that the protoplasm of the hepatic cell does not 
possess, In common with protoplasm in general, the power to produce 
this change. The possibility of fat being formed from proteid is shown 
by the fact that in dogs subjected to a twelve-day period of inanition, 
and to which phosphorus is then administered, the liver contains from 
two to four times as much fat as in the normal animal—the amount 
of fat in the muscles being also greatly in excess of the normal amount.? 
This question of the formation of carbohydrate and of fat from proteid, — 
both within the liver cells and elsewhere, will be considered later on. 

The circumstances that in mammals urea, and in birds uric acid, 
occur in a larger proportion in the liver than in any other organ in the 
body, that there is an increase of urea in blood which has been passed 
through the liver, provided such blood is derived from an animal during 
absorption of proteid food, and that if blood containing certain ammonia 
compounds is passed through the liver it receives a very appreciable 
addition of urea,? all point to the fact, which is now unquestioned, that 
urea and uric acid are produced, if not exclusively, at all events mainly, 
in this organ. 

But the urea which is found in the liver, and which is passed by the 
hepatic capillaries into the hepatic blood, although ultimately derived 
from the proteids of the food, is in all probability not to any appreciable 
extent immediately so derived. If this were to be the case, we should 
have, as with the formation of leucine and tyrosine in the intestine, so 
far as the tissues generally are concerned, a waste of nutritive material— 
a condition which is unlikely to obtain to any extent in the animal 
economy. It may therefore be taken for granted that the great part of 
the proteid which is absorbed from the intestine passes on through the 
hepatic veins into the general circulation, without being stored or at 
once modified in the liver ; and since, after the absorption of any large 
amount of proteid from the alimentary canal, the relative and absolute 
amount of proteid in the blood and lymph is not materially altered, we 
may assume that the excess proteid is stored somewhere else. 

The place of such storage is probably not far to seek. The fact that 
an increase of assimilated proteid in the blood rapidly increases the 
metabolism of muscles, points at once to such proteid passing into the 

1 Storch, Diss., Kjébenhavn, 1865 ; Deutsches Arch. f. klin. Med., Leipzig, 1867, Bd. ii. 
S. 264; Bauer, Zschr. 7. Biol., Mimchen, 1871, Bd. vii. S. 63; 1878, Bd. xiv. S. 527; 
Caseneuve, Rev. mens. de méd. et chir., Paris, 1880, tome iv. pp. 265, 444 ; Stolnikow, Arch. 
f. Physiol., Leipzig, 1887, Suppl., S. 1. 

* vy. Schroder, Arch. f. exper. Path. u. Pharmakol., Leipzig, 1882, Bd. xv. S. 364; 
ibid., 1885, Bd. xix. 8. 273; Salomon, Virchow’s Archiv, 1884, Bd. xevii. S. 149. 


INFLUENCE OF LIVER ON PROTEID METABOLISM. 903 


muscles ; and since such increased metabolism continues during some 
time, the excess proteid must be supposed to be in the first instance 
stored within them. 

The influence of assimilated proteids in increasing the metabolism of 
the tissues, and the manner in which such increased metabolism is 
brought about, has received the attention of many workers. According 
to the view held by Voit, which has been already referred to, such 
additional proteid is not built up into the bioplasm of the tissues, but 
passes into the tissues, and; by contact with the bioplasm, stimulates it 
to increased metabolism ; such metabolism occurring, according to Voit, 
entirely in the circulating proteid, and outside, in a sense, the actual 
bioplasm. On the other hand, according to the view which has been 
strenuously supported by Pfliiger, such excess of proteid is directly 
stored, not in the interstices of the bioplasm, but by being built up into 
its constitution; so that this substance grows at the expense of any 
excess of proteid pabulum which is brought to it by the circulating 
fluid, and such growth or increased nutrition of living substance in itself 
directly promotes an increased destruction. 

That this view is, at least in part, correct, appears from the experi- 
ments by Schondorff, which were carried out under Ptliiger’s direction.? 
Schondorff perfused blood, taken from a dog which had been kept fasting 
for some days—(1) through the limbs, and then through the liver, of a 
well-nourished dog, which had been kept chiefly upon proteid food, and 
which was killed immediately before the experiment; (2) through the 
limbs, and then through the liver, of a dog which had been kept fasting 
for some days ; and (3) blood, which was taken from a well-nourished dog, 
was passed through the limbs and liver of a fasting animal. In five 
experiments in which blood from a fasting animal was sent through the 
organs of a well-nourished dog, the urea of the perfused blood was in- 
creased by amounts varying from about a quarter to more than double 
its original quantity. Out of five experiments, in which the blood of a 
fasting animal was sent through the organs of a fasting animal, the 
amount of urea was diminished in two by 9°55 and 6-9 per cent., while 
in three it was hardly appreciably altered. In these cases, there- 
fore, there was practically no proteid metabolism. In two experiments 
in which the blood of a well-nourished animal was sent through the 
organs of a fasting animal, the urea of the blood was diminished by 
13°5 and 14-4 per cent. There was therefore also here no proteid meta- 
bolism, the diminution of the urea having been probably due to diffusion 
out of the blood into the tissues. That the increase which was obtained 
by passing the blood of a fasting animal through well-nourished organs 
was not due to the diffusion of pre-existing urea from the well-nourished 
liver, was determined by a control experiment, in which it was found 
that the amount of such diffusion was at most very small.” 


These experiments show, according to Pfliiger,? that the effect of increased 
proteid food has been to produce change in the bioplasm, directly causing 
this to grow and to become more active in its metabolism ; whereas, on the 
other hand, a diminution of proteid food has produced the reverse change, 
namely, diminution in amount of bioplasm, with inactivity of proteid 


1 Arch. f. d. ges. Physiol., Bonn, 1893, Bd. liv. S. 420. 

2 The amount of urea in the blood of the starved dogs averaged 0°0348 per cent. ; the 
maximum amount in the proteid-fed dogs, 0°1529 per cent. 

3 Arch. f. d. ges. Physiol., Bonn, 1893, Bd. liv. S. 408. 


904 METABOLISM. 


metabolism, even at a time when the tissues are temporarily supplied with 
circulating proteid from the blood of a well-nourished animal. 

That a continuance of liberal proteid diet does produce an increased growth 
of muscular tissue, may also be looked upon as extremely probable, from the 
daily experience of athletes. As is well known, the diet upon which training 
is chiefly carried out consists very largely of proteid matter, the proteids of the 
food being in much larger proportion to the fats and carbohydrates than in the 
normal diet of untrained persons. It would appear lkely that this, which is 
the result of the experience of many generations of trainers, must have a 
physiological basis, and that the effect of such excess of proteid in the diet 
must in itself not only cause an increase of the proteid metabolism, but also 
lead to the formation of actual tissue proteid. | Under ordinary circumstances, 
however, whether the proteid which passes to the muscles is actually built up 
into their tissue, or whether it is simply included in the interstices of the 
living substance, it is not stored there for long; for it is found, after a meal 
containing much proteid, that within a few hours practically the whole of the 
proteid which has been absorbed is removed in the form of urea. 


That the change in proteid which results in the formation of urea 
must primarily occur within the muscles, within which, as we have 
seen, the greater part of the oxidations of the body occur, there can be very 
little doubt. But there has always been this difficulty in connection 
with the question, that although urea is the ultimate product of proteid 
metabolism, the muscles practically contain either no urea or only a 
very smallamount. An exception is, it is true, found in certain animals, 
e.g. the Elasmobranch fishes, the muscles of which contain a considerable 
amount of urea. But this is not the case with most animals, and it 
cannot be supposed that urea is formed to any appreciable amount in 
the muscles, especially since we know that by far the greatest amount 
is actually formed in the liver. 

What precursor, therefore, of urea is formed in the muscles from the 
proteid which is metabolised within them? The nitrogenous substance 
which could best be supposed to be produced from the metabolism of pro- 
teids, is creatine, since this is the one found in largest amount within 
the muscles; and it is natural to suppose that creatine, which is capable 
of being converted in the laboratory without any great difficulty into 
urea and sarcosine, might be the immediate precursor of urea. It is, 
however, found that if creatine is injected into the blood or subcutane- 
ously, or if it is taken with food, and thus absorbed into the blood, it 
does not become converted into urea, but is found in the urine as 
creatinine; and we cannot therefore suppose that the creatine of the 
muscles is absorbed by the blood, and carried by that fluid to the liver, 
and there converted into urea, since we find that creatine added to the 
blood does not become so converted. 

Without ignoring the possibility that the creatine which is found in 
muscle may still be a preliminary stage in the transformation of 
proteid into urea, we must look for other products of nitrogenous 
metabolism passing from the muscles which, whether derived immedi- 
ately from the proteid or indirectly from it through creatine, may be 
supposed to be the real precursors of urea. As a matter of fact, such 
products are found in the form of ammonia salts. It was noticed by 
Schondorff, in the experiments already quoted, that in cases in which 
the blood of a fasting animal was sent through the limbs only of a well- 

1 Stadeler and Frerichs, Journ. f. prakt. Chem., Leipzig, 1858, Bd. lxxiii. S. 48. 


INFLUENCE OF LIVER ON PROTEID METABOLISM. 905 


nourished animal, there was an increase of ammonia salts in the blood. 
It is also a well-established fact that certain ammonia salts passed 
through the liver along with the blood become synthetised within the 
liver into urea. The actual form which such ammonia salts probably 
take is that of a combination with sarcolactic acid, which is also, 
as is well known, produced in muscle, and which is found, probably 
in combination with ammonia, in the blood generally.. These facts 
render it not improbable that the ultimate condition of the proteid 
which has been metabolised in muscle is lactate of ammonia (whether 
passing through the intermediate condition of creatine or not). This 
lactate of ammonia passing into the general circulation and being 
conveyed to the liver is there converted in mammals into urea, in 
birds into uric acid, in which form it is excreted by the kidneys. In 
conformity with this it was found by Marfori? that lactate of ammonia 
injected into the vein of a dog at the rate of 60 to 100 mgrms. per 
kilo. per hour, was wholly changed to urea. The rest of the molecule, 
there can be very little doubt, is oxidised and got rid of in the form 
of carbon dioxide and water. 

What intermediate changes may be gone through between the 
splitting of the proteid molecule into a nitrogenous and non-nitrogenous 
part, and the ultimate oxidation of the non-nitrogenous part into 
carbon dioxide and water, is a matter mainly of conjecture; but since we 
find within the muscular tissue, as an almost constant constituent, 
glycogen, it is conceivable that in part at least the split-off non- 
nitrogenous portion of the proteid molecule may first become converted 
into that substance, and possibly into grape-sugar, to be subsequently 
further split up and oxidised to form the ultimate products of oxidation. 

That the proteid molecule can split up into a nitrogenous part and a 
part which is capable of being converted into carbohydrate, is shown 
very strikingly by the phenomena of diabetes, whether natural and of 
the severe form, or whether due to the administration of phloridzin or 
pancreatic extirpation. In these cases, even when the diet is ex- 
clusively proteid, or even when food is altogether withheld and the 
starving animal is compelled to live mainly upon the proteids of its own 
tissue, sugar becomes formed in great amount, and must be produced by 
the transformation of proteids. It is not unreasonable to suppose that 
this is merely an abnormally heightened form of the normal condition 
of things, and that under ordinary circumstances a similar transformation 
of the proteid molecule may go on in the muscles, for in phloridzin 
diabetes at any rate * the formation of sugar is independent of the liver. 

With regard to the sulphur of the metamorphosed proteids, this 


1Gaglio, Arch. f. Physiol., Leipzig, 1886, S. 400. Gaglio showed not only that lactic 
acid is constantly present in the blood, but that its amount is increased in blood perfused 
through various ‘‘ surviving ” organs (kidneys, lungs). See also p. 159 of this volume. 
V. Frey also obtained an increase of lactic acid in blood which had been perfused through 
“surviving ” muscle (4rch. f. Physiol., Leipzig, 1885, S. 533). 

2 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1893, Bd. xxxi. S. 71. 

3 Minkowski found that in geese, after extirpation of the liver, the ammonia of the urine, 
which in normal geese amounts to from 9 to 18 per cent. of the total nitrogen, was 
increased to from 50 to 60 per cent. (Arch. f. exper. Path. u. Pharmakol., Leipzig, 1886, Bd. 
xxi. S. 41; and dbid., 1893, Bd. xxxi. S. 214), whilst the uric acid almost disappeared. 
The ammonia was in the form of lactate, although in the normal animal there is no 
appreciable amount of Jactic acid in the urine. 

4In pancreatic diabetes, according to Marcuse (Verhandl. d. physiol. Gesellsch. zu 
Berlin, 1893-4, 8S. 98), this is not the case. Frogs deprived of liver, as well as pancreas, 
although they lived 3 to 5 days, showed no glycosuria. 


906 METABOLISM. 


undoubtedly is mainly transformed by oxidation into sulphate, for it is 
found that the sulphates of the urine go hand in hand with the amount 
of proteid metabolism which is proceeding (see also p. 630). 

Nitrogenous metabolism in the liver.—That a very important part 
of the nitrogenous metabolism of the body occurs in the liver, has been 
insisted upon, and the experiments which have led to our knowledge on 
this matter have already been incidentally referred to. 

Urea.—The evidence of the formation of urea in the liver was 
obtained by v. Schroder in a series of researches of remarkable interest 
and importance. Schroder! first determined that this substance was not 
formed in the kidneys, at least exclusively. He found that when the 
kidneys were extirpated in a dog, the amount of urea in the blood was 
increased in the next twenty-four hours to four times the normal 
quantity (from 0°05 per cent. to 0-2 per cent.). Nor was he able to 
obtain any increase of urea in blood passed through the kidney, even 
when such blood contained substances (e.g. carbonate of ammonia) which, 
by the liver, are capable of being synthetised into urea. This is the 
more striking, because, as we have seen, the kidneys are capable of 
performing such an important synthetic process as the formation of 
hippuric acid from benzoic acid and glycine (Bunge). 

Schréder also showed that urea is not formed in the muscles. 
He found that blood containing carbonate of ammonia, when perfused 
through the hind-limbs of a dog, showed no increase of urea. On the 
other hand, blood similarly treated, and passed several times through 
the liver of a freshly-killed animal, was found to contain twice or three 
times the amount of urea which it had before passing through the 
organ. It was necessary for success in these experiments that the liver 
should be taken from a well-nourished animal. If removed from a 
fasting dog no urea was formed. A similar result, obtained by 
Schondorff, has been already referred to (p. 903). 

These experiments were repeated by Salomon? both upon sheep 
and dogs. They show conclusively that the liver is capable of 
forming urea from carbonate of ammonia. We have already seen 
that it is also capable of forming urea from blood containing the 
products of digestion. Other salts of ammonia besides carbonate 
are found to be effective; amongst others lactate and carbamate 
of ammonia, and also the amido-acids, such as leucine and glycine. 
On the other hand, in extensive disease of the liver, especially 
of rapid occurrence, and in experiments involving removal of the 
liver in mammals, combined with the establishment of a communica- 
tion between the portal and the general venous system, so that 
there should be no stasis of blood in the capillaries of the intestinal 
circulation, ammonia salts are found to largely replace urea in the urine, 
such salts taking the form of lactates and of carbamates (p. 908). With 
partial extirpation of the liver and also with phosphorus poisoning, in 
which the liver cells undergo extensive degeneration, there is also a 
greater or less diminution of urea in the urine, and a corresponding 
increase of ammonia; as regeneration occurs, the urea becomes again 
gradually increased. The same has also been noted in extensive disease 
of the liver, especially when of rapid occurrence, but also in cases of 


1 See note 2, p. 902. 2 Ibid. 
3 Ponfick (in rabbit), Virchow’s Archiv, Bde. exviii. S. 225 ; cxix. S. 193, cxxxviii. Suppl. 
S. 81; v. Meister (in cat and dog), Centralbi. f. allg. Path. u. path. Anat., Jena, 1891, Bd. ii. 


UREA. 907 


cirrhosis ; the ammonia is usually accompanied by lactic acid.’ In acute 
yellow atrophy there is besides a considerable amount of leucine and 
tyrosine. When carbonate of ammonia is administered to mammals, the 
excretion of ammonia is not increased in the urine, but urea is formed 
in proportion to the amount of ammonium carbonate ingested.” 


It is possible that, as Drechsel® supposes, carbamate of ammonia may be 
the immediate precursor of urea, the carbonate being first converted into 
carbamate and then into urea. By elimination of one molecule of water, 
carbonate of ammonia forms carbamate, and by elimination of a second 
molecule, urea.* 


/O(NH,) /NH, /NH, 
eo C=O C—O 

\ O(NH,) \.0(NH,) \ NH, 
(carbonate of ammonia) (carbamate of ammonia) (urea) 


When chloride of ammonia is administered with the food in herbivora 
(rabbits), the whole of the ingested ammonia appears as urea in the urine, 
but in carnivora and in man some of the ammonia is excreted in the urine.® 
The difference is due to the fact that the inorganic salts of the food of 
herbivora contain an excess of potassium carbonate. This takes the hydro- 
chloric acid from the chloride of ammonia, and carbonate of ammonia is 
formed, which is readily converted into urea. But when there is an excess of 
proteid in the diet, sulphuric acid is formed by oxidation, and this combines 
with any bases present, so that the ammonia is not set free from the hydro- 
chloric acid, and the chloride of ammonia passes unchanged (Bunge). In 
fasting dogs all the ammonia administered may be recovered from the urine.® 

It is obvious that the formation by synthesis of the neutral substance 
urea from the alkaline salt, carbonate of ammonia, which is formed in the 
metabolism of proteid, is a protection from the deleterious effects which 
might otherwise ensue from too high an alkalinity of the circulating fluid 
and urine. 


The presumption, therefore, undoubtedly is, that under ordinary 
circumstances the ultimate transformation of the products of nitro- 
genous metabolism takes place under the influence of the hepatic cells.’ 


1 For references consult Bunge’s ‘‘ Lectures,” pp. 327 and 345; also Neumeister, 
“Lehrbuch,” S. 315. 

2 Hallervorden (with Schmiedeberg), Arch. f. caper. Path. u. Pharmakol., Leipzig, 
1880, Bd. xii. S. 237 ; Feder and E. Voit, Ztschr. f. Biol., Miinehen, 1880, Bd. xvi. S. 177. 
Feder and Voit found that acetate of ammonia also forms urea. The same thing was 
determined for citrate of ammonia by Lohrer, with Buchheim (Diss., Dorpat, 1862). This 
is the reason why citrate of ammonia does not, like citrate of potash, make the urine 
alkaline. Both citrates are converted into carbonates in the body, but the carbonate 
of ammonia becomes transformed into the neutral urea, while the carbonate of potash 
passes as such into the urine. 

3 Ber. d. k. siichs. Gesellsch. d. Wissensch., 1875, S. 171; Journ. f. prakt. Chem., 
Leipzig, 1875, N.F., Bd. xii. ; 1877, Bd. xvi. ; 1880, Bd. xxii. ; Arch. f. Physiol., Leipzig, 
1880, S. 550. 

4 Hoppe-Seyler (Ber. d. deutsch. chem. Gesellsch., Berlin, 1874, Bd. vii. S. 34) and 
Salkowski (Centralbl. f. d. med. Wissensch., Berlin, 1875, S. 913; and Zéschr. f. physiol. 
Chem., Strassburg, 1877, Bd. i. S. 26) regard it as probable that cyanic acid may be the 
immediate precursor of urea, which is readily formed from cyanate of ammonia. But the 
evidence in favour of this supposition is by no means suflicient, whereas that in favour 
of ammonium carbonate (and carbamate) being the precursor, is very strong. 

5 y. Knieriem, Zéschr. f. Biol., Miinchen, 1874, Bd. x. 8. 263; Salkowski, Ztschr. f. 
physiol. Chem., Strassburg, 1897, Bd. i. S. 1. 

6 Feder, Ztschr. f. Biol., Miinchen, 1877, Bd. xiii. S. 256. 

7 Richet has shown that a urea-forming ferment can be precipitated by alcohol from 
aqueous extract of liver (Compt. rend. Soc. de biol., Paris, 1894, p. 525). 


908 METABOLISM. 


It must not, however, be assumed that the whole of this ultimate 
metabolism occurs in the liver, for, as a matter of fact, after complete 
destruction of the liver by disease, or after its complete removal or 
destruction by operation, the urea of the urine does not wholly dis- 
appear, although in large measure replaced by ammonium salts (and 
under some circumstances by leucine and tyrosine). It is not certainly 
known in what other organs urea may be formed. The occurrence of a 
large amount of urea in the muscles of Elasmobranchs might seem to 
point to the muscles as the possible source of such urea.! But, on the 
other hand, as we have seen, v. Schréder was unable to obtain any 
evidence of the appearance of urea in blood perfused through muscles 
of dogs. It is, on the whole, more probable that other glandular organs 
may have some share in its production.? 


The total removal or destruction of the liver in mammals has been 
rendered possible, by the discovery that it is feasible to establish a permanent 
communication between the portal vein and the inferior vena cava (Kck’s 
fistula),? and thus, after tying the hepatic artery as well as the portal vein, to 
shunt the liver altogether out of the circulation; in fact, after such a fistula 
is established, the organ may be altogether removed. A large number of 
such operations have been made upon dogs by Hahn, Massen, Nencki, 
and J. Pawlow, and the results upon general, and especially nitrogenous 
metabolism, carefully recorded. About one-third of the number in which 
the fistula was established recovered from the effects of the operation, but 
those in which the organ was completely removed only lived a few hours. 
Many of those with the Eck fistula refused food. These soon showed 
symptoms of convulsions, and eventually died. Those which fed well 
recovered weight, and showed no very obvious symptoms, unless given an 
excess of proteid food; this invariably brought on convulsions. The same 
result was produced by giving carbamic salts with the food (although these 
produce no such symptom in normal dogs). The urea was only slightly 
diminished in those with the Eck fistula only (but greatly so when the liver 
was completely removed) ; the uric acid excreted was at first greatly increased 
(four times), but afterwards became normal; the ammonium salts in the urine 
were increased, and were partly in the form of carbamate. Merely tying the 
hepatic artery in rabbits may also cause the appearance of ammonium lactate in 
the urine,® a result probably due to interference with its oxidation to car- 
bonate of ammonia, and the synthesis of this to urea. The amount gradually 
diminishes, under these circumstances, as a collateral arterial circulation 
becomes established in the liver. 

Nencki, Pawlow, and Zaleski® found that the portal blood of flesh-fed dogs 
contains three and a half times as much ammonia as the hepatic blood. 
Nevertheless the amount in the portal vein (which they calculated to have 
been 4°73 grms. in ten hours in a dog weighing 9°5 kilos.) was too small to 


' The muscles of Elasmobranchs were found by v. Schréder (Ztschr. f. physiol. Chem., 
Strassburg, 1890, Bd. xiv. S. 576) to contain 2 per cent. of urea ; the blood, 2°6 per cent. ; the 
liver, 1°36 per cent. The amount found in the muscles remained the same after removal 
of the liver. It is therefore evident that the conditions of nitrogenous metabcelism are 
quite different in these animals from those met with in mammals. 

* Cf. Mitnzer, Arch. f. exper. Path. u. Pharmakol., Leipzig, 1894, Bd. xxxiii. S. 164; 
Kaufmann, Arch. de physiol. norm. et path., Paris, 1894, p. 531. 

3 Eek, Trav. Soc. d. natur. de St. Péersbourg, 1879, tome x. 

* Arch. de sc. biol., St. Pétersbourg, 1892, tome i. p. 401; Arch. f. exper. Path. 
u. Pharmakol., Leipzig, 1893, Bd. xxxii. S. 161. See also Stern, ibid., Bd. xix. S. 45; 
and y. Schroder, ibid., S. 373. 

° Zillessen, Ztschr. f. physiol. Chem., Strassburg, 1891, Bd. xv. S. 387. 

§ Arch. f. exper. Path. u. Pharmakol., Leipzig, 1896, Bd. xxxvii. S. 26. 


URIC ACID. 909 


account for the whole of the urea excreted by the kidneys; they consider, 
therefore, that it must be partly formed in other organs. 


Uric acid.—In those animals in which the ultimate product of 
nitrogenous metabolism is uric acid instead of urea, it is probable that 
the primary changes which go on in the muscles result in the formation 
of similar substances (lactic acid and ammonia) as are formed as 
antecedents of urea, and that the secondary change to uric acid occurs 
in the liver. For, after extirpation of the liver in birds, these substances 
are found in the urine replacing uric acid." 


Minkowski? removed the liver in geese, taking advantage of the fact that 
in birds there exists a vein (Jacobson’s vein) which effects a communication 
between the portal vein and the vena advehens of the kidney, so that when the 
portal vein is tied beyond this communication the blood of the mesenteric veins 
passes through the kidneys, and is not caused to stagnate as in mammals. In 
some animals he merely tied the portal vein, in others he completely removed 
the liver ; these, however, only survived the operation a few hours (at most 
twenty). The uric acid of the urine sank as the result of this operation, so that 
from representing 60 to 70 per cent. of the total nitrogen of that secretion, as in 
normal animals, it represented only 3 to 6 per cent., the amount of ammonia in 
the form of lactate being correspondingly increased. The lactic acid found in 
the urine under these circumstances is the sarcolactic which is formed in 
muscular tissue ; it is present in even larger proportions than ammonia, so that 
the urine is strongly acid. Altogether half the solids of the urine were formed 
of ammonium lactate, although in the normal animal none is present. No 
amido-acids were found in the urine, and no sulphates. The urea and creatine 
were unaltered in amount. In the blood, lactic acid was present and also some 
leucine and tyrosine. Urea injected into the stomach appeared as such in 
the urine, although in the normal goose it is converted into uric acid. The 
administration of glycine and asparagine caused a great increase in the 
ammonia of the urine. The same effect as extirpation—namely, the replace- 
ment of uric acid by lactate of ammonia—may be produced by merely tying 
the hepatic artery in birds,® a result which is probably due to the fact that the 
oxidations within the organ have been thereby so greatly interfered with, that 
the transformation of the lactate of ammonia into carbonate and the subsequent 
synthesis of uric acid has been prevented. That uric acid can be formed in 
vitro from lactic acid, ammonia, and carbonic acid, has been shown by 
Horbaczewski, who obtained uric acid by heating trichlorlactamide with urea 
(see p. 587). 


We are, however, not justified in assuming that the uric acid which 
is found in the urine of mammals runs a parallel course in its formation 
with that taken in the formation of urea. For, in the first place, it is not 
in them, as in birds, necessarily increased in amount by the ingestion of 
proteid food, nor does it go hand in hand with the excretion of urea. 
And whereas in birds the ingestion of the amido-acids and of ammonia 


1 y. Schréder showed that uric acid is not formed in the kidneys in birds and snakes, 
but that after the removal of those organs it accumulates in the blood and tissues (Arch. f. 
Physiol., Leipzig, 1880, Suppl. S. 113; Beitr. z. Physiol. C. Ludwig 2. s. 70 Geburtst., 
Leipzig, 1887, S. 89). v. Schréder also showed, in confirmation of an earlier observation of 
Meissner, that the liver of birds contains more uric acid than the blood. According to 
A. Garrod (Proc. Roy. Soc. London, 1893, vol. liii. p. 478), there is no uric acid normally 
in birds’ blood, and this contains as much urea as that of amammal. Garrod is of opinion 
that uric acid is produced in the kidneys by synthesis of urea and glycine. If the results 
of v. Schréder are correct, it is difficult to understand this conclusion. 

2 Arch. f. exper. Path. v. Pharmakol., Leipzig, 1886, Bd. xxi. S. 41. 

3 Minkowski, ibid., 1893, Bd. xxxi. S. 214. 


gio METABOLISM. 


salts is followed by an increase of uric acid in the urine, such substances 
given with the food to mammals and man produce only an increase in 
the urea excreted. The same thing occurs even when uric acid itself is 
given to dogs, whereas the addition of urea to the food of birds produces 
an increase in the uric acid excreted! There is in fact a fundamental 
difference in this respect between the proteid metabolism of mammals as 
compared with birds and reptiles, but the difference is in the later stage 
of such metabolism, which occurs in the liver, and not in the earlier 
stage, which occurs in the muscles. It has been noticed that in 
mammals the diet which most tends to produce an increase of uric 
acid is glandular substance and especially thymus gland, which con- 
tains a large amount of nucleo-proteid. It is not increased by a 
flesh diet, unless this includes nucleo-proteids ; whereas in affections in 
which there is an increased formation (and presumably therefore also an 
increased destruction) of lymph cells (leucocytosis), a marked increase of 
uric acid has been noticed (e.g. in leukeemia).? 

For a further discussion of this subject, see “Chemistry of the 
Urine,” pp. 593-596. 


Mares? found the uric acid of the urine to be increased during digestion ; 

he ascribes this to the activity of glandular cells and increased metabolism of 
nucleo-proteids. In accordance with this view, he found pilocarpine to 
produce a similar increase. Horbaczewski* found the uric acid diminished 
in cases of cirrhosis of the liver, and concludes, therefore, that it is not 
formed in man in this organ. On the other hand, by digesting spleen 
pulp (which normally contains neither uric acid nor xanthin nor hypo- 
xanthin) with arterial blood at 40° C., he obtained a considerable forma- 
tion of uric acid, and the same when nuclein was used instead of spleen 
pulp. 
"Uiie acid given to mammals (dogs) with their food does not increase the 
uric acid of the urine but the urea. In all probability it becomes transformed 
into urea in the liver. The uric acid which is found in the urine, and which 
has probably been formed from the nucleo-proteid of the food, or of degenerated 
cells of the tissues, may be supposed to have reached the kidneys without 
having passed through the liver. 

If in a dog with an Eck’s fistula the uric acid in the urine be estimated, 
and the hepatic artery then tied, it is found that the uric acid in the urine is 
largely increased. This may be explained by supposing that the uric acid 
formed from the products of disintegration of nucleo-proteids of cells, such as 
those of the spleen and lymphatic glands, has not been transformed into urea, 
as would be the case were it allowed to pass through the liver. Those 
products of disintegration are proteids, phosphates, and xanthin- (alloxuric) 
bases. The latter partly undergo further oxidation into uric acid, partly are 
eliminated directly by the kidneys as xanthin or hypoxanthin. They are 
increased in blood which has been perfused through almost all organs of 


1 Hypoxanthin given to birds also markedly increases the uric acid of the urine ; this 
also occurs, however, when the liver is removed. It is therefore probably transformed by 
a process of simple oxidation in the tissues (v. Mach, with Minkowski, Arch. f. exper. 
Path. u. Pharmakol., Leipzig, 1887, Bd. xxiii. 8. 139). 

2 Stadthagen, Virchow’s Archiv, 1887, Bd. cix. S. 390, found no uric acid in the spleen 
or liver in cases of leukemia, but abundance of xanthin and hypoxanthin. There was a great 
increase of uric acid in the urine, but this was not further increased by giving uric acid 
with the food. 

3 Arch. slaves de biol., Paris, 1887, tome iii. p. 207. 

4 Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1889, Bd. xcviii., Abth. 3, S. 301; zbid., 
1891, Bd. c. 8S. 78; Arch. f. Physiol., Leipzig, 1898, S. 109. Cf. Mares, Sitzungsb. d. k. 
Akad. d. Wissensch., Wien, Bd. ci., Abth. 3, S. 12. 


INFLUENCE OF ACTIVITY ON PROTEID METABOLISM. 911 


the body, but especially those with much lymphoid tissue! In amphibia 
and fishes the oxidation to uric acid does not occur, and this substance is not 
found in the urine.? Part of the uric acid of the bird’s urine appears to be 
produced in the same manner as in mammals, and does not disappear after 
extirpation of the liver.* 


Influence of muscular activity on proteid metabolism.—As 
we have already insisted upon, the greater part of the metabolism of 
the body goes on in the muscles. This is the case both when at rest 
and in activity, but their metabolism is greatly increased during activity. 
This is sufficiently shown by the fact that a much larger amount of 
carbonic acid is given off from the body when the muscles are con- 
tracting actively than when in a condition of rest; and the chemical 
changes which can be shown to occur in the muscles as a result of 
contraction, such as the production of sarcolactic acid and of CO,, as 
well as the disappearance of glycogen, must mean increased metabolism. 


Although there is a general consensus of opinion that the CO, output 
of the body is largely increased as a result of muscular activity, the evidence 
that the CO, leaves the muscles as such is by no means conclusive. The 
observations which have been made upon this subject are of two kinds, 
namely, (a) the observation of the CO, given off by excised “surviving” 
frog’s muscle, tetanised at intervals, as compared with the amount given off by 
corresponding muscle at rest ; and (6) the observation of the amount of CO, in 
the venous blood of the muscles of mammals, taken during conditions of rest 
and of contraction of the muscles respectively. The best-known experiments 
of the first kind are those of L. Hermann,‘ in confirmation of the results of 
Matteuci® and Valentin,® who found that the CO, yielded by tetanised frog 
muscles was greater in amount than that yielded by resting muscles under like 
conditions. The difference, however, was greatly diminished by agitation of 
non-contracting muscles. A careful repetition of this experiment, conducted 
in 1893-4 in my laboratory, by L. Hill,’ failed to show to the most careful 
analysis any appreciable difference in the CO, output of two such 
sets of muscles (contracting and resting). Similar experiments by Tissot § 
yielded results confirmatory of those of Hermann. Recently the question 
has been again investigated by Fletcher,? who employed a titration method 
for the ies of ae CO,, and made use of the extremely accurate ap- 
paratus devised by Blackman " for estimating the gaseous exchanges in plants. 
Fletcher, both with skeletal and with cardiac muscle (tortoise), was able 
to obtain only the smallest possible difference of CO, output between rest 
and contraction, and he comes to the conclusion that the contrary 
results obtained by Hermann and others are due to the prolonged stimula- 
tion inducing the commencement of rigor mortis, a condition which is 
attended by a considerable output of CO,. The other method of investi- 
gation, by the estimation of the CO, contained in the blood which has 
passed through muscular tissue, as compared with that entering it, was 
first undertaken by Ludwig and Sczelkow! upon muscles im situ in the 


1 Horbaczewski, Monatsh. f. Chem., Wien, 1889, Bd. x. S. 624, and Joc. cit., supra. 
2 Nebelthau, Zischr. f Biol., Miinchen, 1889, Bd. xxv. S. 129. 

= Minkowski, loc. cit. 

4 < Stoffwechsel der Muskeln,” Berlin, 1867. 

5 Ann. de chim. et phys., Paris, 1856, Ser. 3, tome 47. 

6 Arch. f. physiol. Heilk., Stuttgart, 1857. 

7 Hitherto unpublished. 

8 Arch. de physiol. norm. et path., Paris, 1894-5. 

® Communication to the Physiological Society, May 1897, not yet published. 
0 Phil. Trans., London, 1895, vol. clxxxvi. p. 485. 

1 Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1862, Bd. xlv. 


gI2 METABOLISM. 


living animal, and by Ludwig and Schmidt! upon separated and perfused 
muscles of the dog. Most of these experiments showed an increase of CO, 
during contraction, but in some there was no increase. Minot? (also with 
Ludwig), using serum for perfusion instead of blood, could find no relation 
between the CO, output and the contraction of the muscles. He came to the 
conclusion that CO, is not one of the disintegration products formed during 
contraction. Frey and Gruber,® using somewhat improved methods, have, 
however, obtained more distinct evidence of an increase of CO, during con- 
traction ; and a similar result was got by Chauveau and Kaufmann,* who 
investigated the amount of CO, in the blood passing to and from the levator 
labii inferioris of the horse when at rest, and when in natural activity during 
mastication. It must be stated, however, that the results obtained by per- 
fusion of separated mammalian muscles are not altogether free from the 
objection raised by Fletcher regarding the excised surviving muscles of the 
frog, that prolonged excitation may tend to hasten the approach of rigor. 

It is therefore not absolutely certain whether the CO,, which is ultimately 
produced as a result of muscular activity, actually leaves the muscle as such, 
or in some other form, such as lactic acid, which is destined to be further 
oxidised elsewhere.® 


The most interesting question in connection with the special meta- 
bolism of the muscles which remains to be considered, is the effect 
which their exercise produces upon the proteid metabolism of the body. 
It was the opinion of Liebig that the energy of muscular contraction 
was produced by the oxidation of muscular substance, and it would 
follow from this that the exercise of the muscles must tend, ceteris 
paribus, to increase the amount of nitrogen excreted in the urine. 
This doctrine of Liebig was accepted for many years by physio- 
logists, but was, for a time at least, completely overthrown by the 
results of the famous experiment of Fick and Wislicenus,® known as 
the experiment of the ascent of the Faulhorn. It was shown ‘by 
these observers that at least three times as much work was done 
during the ascent as could be accounted for by the oxidation of proteid, 
as estimated by the amount of nitrogen eliminated by them during and 
after the work. 

The work, therefore, could only have been caused by the oxidation 
of non-proteid matter. Similar results were obtained by Parkes’ and 
others in man, and by C. Voit in dogs. This, combined with the fact 
that the CO, output of the body is increased in proportion to the 
amount of exercise, led to the view being widely adopted that the 
energy of the body is mainly, if not entirely, obtained by oxidation of 
non-proteid materials, and that the splitting and oxidation of proteid 


1 Arb. a. d. physiol. Anst. zu Leipzig, 1868. 

2 [bid., 1877. 

3 Arch. f. Physiol., Leipzig, 1885, S. 519. 

4 Compt. rend. Acad. d. sc., Paris, 1887. 

5 For other observations and statistics on the subject, see article ‘‘Chemistry of 
Respiration.” 

6 Vrtljschr. d. naturf. Gesellsch. in Ziirich, 1865, Bd. x. 8. 317. 

7 Proc. Roy. Soc. London, 1872, vol. xx. p. 402. 

8 See Hermann’s ‘‘ Handbuch,” Bd. vi. S. 187. The experiments of Parkes, Voit, and 
North (as well as those by Pavy, Austin Flint, and others, which cannot here be re- 
ferred to in detail), were made upon men and dogs taking walking exercise. It has been 
determined by Zuntz and Katzenstein (in man and horse) that each kilogrammetre of ascent 
work is accompanied by a consumption of oxygen thirteen times that consumed in each 
metre of walking exercise (Arch. f. Physiol., Leipzig, 1890, S. 867, Verhandl. d. physiol. 
Gesellsch. zu Berlin). 


INFLUENCE OF ACTIVITY ON PROTEID METABOLISM. 913 


must contribute, under the ordinary circumstances of a mixed diet, but 
little to the production of muscular energy. 

Many other experiments have been performed of a like nature, and 
leading practically to the same conclusion. A few, however, have given a 
result which has shown a somewhat increased amount of nitrogenous 
excretion,’ but it will be found on an examination of these that in every 
case there has either been an excessive amount of work done, leading to 
probably an abnormal condition of metabolism,” or there has been taken 
in with the food an insufficient amount of non-proteid material to pro- 
vide the necessary oxidation and energy for the work required to be done, 
plus the maintenance of body-temperature. Under such circumstances, 
it is clear that the proteid material of the food must be called upon for 
oxidation and the formation of energy, and we should then naturally 
expect an increased amount of urea in the urine. 

Based upon experiments which come under this heading, Pfiiiger * 
and his pupils have shown a tendency of late years to return to the 
original doctrine of Liebig, and to throw over the view which has been 
accepted almost exclusively since the experiment of Fick and Wislicenus 
above referred to. Thus Argutinsky,* working with Pfliiger, found, in 
repeating the experiment of Fick and Wislicenus in a somewhat modified 
form, that there was a marked increase (12 to 25 per cent.) of nitrogen 
excreted, if not so much during the actual performance of the work, at 
any rate during the two days succeeding it, and that from 75 to 100 per 
cent. of the total work done could be accounted for by oxidation of 
proteid; even with 100 grms. of sugar added to the diet, there was still 
an excess of N excreted sufficient to account for 25 per cent. of the 
work done. Similar experiments by Krummacher and others yielded a 
like result.’ It has, however, been poimted out by I. Munk,® that the 
conditions of the experiments of Argutinsky are not the same as those of 
Fick and Wislicenus, in so far as the amount of food which was taken 
by Argutinsky and Krummacher had an insufficient caloric value to 
produce the required amount of energy, that of Argutinsky representing 
only 18 calories per kilo.; that of Krummacher only 28 calories per 
kilo., whereas a man at rest requires 52 calories per kilo.; as a natural 
result, a part of the proteids of the body was called upon for the pro- 
duction of the necessary energy. That, given a sufficient amount of 
proteid food, and an insufficient amount of non-proteid food, a large 
amount of muscular energy can be produced by oxidation of the proteid 
is no doubt true. Thus, a dog which was kept by Pfltiger for some 
months upon lean meat, containing a very small amount of non-proteid 


1Cf., for example, Austin Flint, Journ. Anat. and Physiol., London, vol. xi. p. 109, 
and vol. xii. p. 91; Pavy, Lancet, London, 1876, vol. ii. Nos. 22-26 ; 1877, vol. i. No. 2; 
W. North, Proc. Roy. Soc. London, 1883, vol. xxxvi. p. 11. 

2 That such nitrogen increase is associated with abnormal conditions, appears from the 
experiments of Oppenheimer (Arch. f. d. ges. Physiol., Bonn, 1880, Bd. xxii. S. 40 and 
Bd. xxiii. S. 446), of Zuntz and Schermberg (Arch. f. Physiol., Leipzig, 1895, S. 378), and of 
Oddi and Tarulli (Bul/. d. r. Accad. med. di Roma, tome xix. pp. 2 and 57). 

3 *<Thie Quelle der Muskelkraft,” Arch. f. d. ges. Physiol., Bonn, 1891, Bd. 1. S. 98. 

4 Arch. f. d. ges. Physiol., Bonn, 1889, Bd. xlvi. S. 552. 

> Thid., 1890, Bd. xlvii. S. 454; see also Pfliiger and Bohland, dbid., 1885, Bd. xxxvi. 
8. 165; Bleibtreu and Bohland, zbid., 1886, Bd. xxxviii. S. 1. 

6 Arch. f. Physiol., Leipzig, 1890, S. 557 (Verhandl. d. physiol. Gesellsch. zu Berlin, 
1889-90, No. 12). Cf. also Hirschfeld, Virchow’s Archiv, 1890, Bd. exxi. S. 501, who 
obtained a marked increase of N in the excreta when working on insufficient diet, but not 
when the diet, whether proteid or non-proteid, was sufficient. Further, Sondén and 
Tigerstedt, Skandin. Arch. f. Physiol., Leipzig, 1895, Bd. vi. S. 181. 


VOL. 1.—58 


914 METABOLISM. 


matter, was nevertheless able to perform a large amount of muscular 
work, metabolising at the same time a very considerable amount of 
proteid, the oxidation of which could have been the only source of the 
greater part of the energy. Whether, however, as Pfliiger holds, the 
living tissue prefers to employ proteid, when it has sufficient offered to it, 
for the production of work, or whether, as is generally supposed, it 
uses up first the available non-proteid material for the production of 
energy, and only secondarily calls upon the proteid for the purpose of 
oxidation and energy production, is a matter which it is not at all easy 
to settle. That proteids enter largely into the diet of athletes is a 
fact which is of some importance in connection with the question. 
But although for short periods athletes are unquestionably capable of 
doing a very large amount of work, it must be remembered that their 
diet is by no means rigidly confined to proteid substances. It must 
also be borne in mind that there is a large class of labourers both in 
this, but more especially in other countries, who get through a much 
larger average amount of work per diem than is performed by athletes, 
and who, nevertheless, frequently have an amount of proteid in their diet 
the oxidation of which is altogether insufficient to account for the work 
done. The fact that a proteid diet has been selected for training purposes 
may be due, in the first place, to the more ready assimilation of proteid by 
the body ; and, in the second place, to the fact that it is specially required 
in these cases, because during training it is important to encourage the 
building up of muscular tissue, and for this purpose proteid is necessary ; 
not because the proteid of the diet is itself more readily oxidised and 
converted into energy by oxidation than the non-proteid materials. 

But whether there may be produced under some circumstances as 
the result of muscular exercise an increase in the nitrogen of the egesta, 
it is certain that the most prominent effect upon the egesta of activity 
of the muscles is an increase in the amount of carbon dioxide,! such 
increase being either unaccompanied by, or altogether disproportionate 
to, any rise in the nitrogen egested. It must therefore arise from the 
oxidation of non-nitrogenous materials, ze. fat and carbohydrates. 

Cl. Bernard was of opinion that the grape-sugar which he had dis- 
covered in the liver and in the blood might by its oxidation in the 
tissues take an important part in the production both of heat and of 
mechanical energy. Seegen? is disposed to go much further than 
this, holding that muscular energy is obtained solely from the oxidation 
of dextrose brought to the muscles by the blood. He finds, as others 
have done, that sugar is never absent from the blood even after pro- 
longed fasting, and that there is an excess of glucose in the hepatic 
blood, independent of the presence or absence of glycogen in the liver. 
He also finds in most cases a diminution in the percentage amount of 
sugar in the venous blood leaving a muscle, as compared with that in 
arterial blood. Some of Seegen’s results are, however, paradoxical, 
nor have they received adequate confirmation, although a similar 


1 Cf. article ‘‘ Chemistry of Respiration.” 

2 “Die Zuckerbildung im Thierkorper,” Berlin, 1890; and Arch. f. d. ges. Physiol., Bonn, 
1891, Bd. 1., which volume also contains a criticism of Seegen’s views by Pfliiger. See also 
on this subject I. Munk, Verhandl. d. physiol. Gesellsch. zu Berlin, in the Arch. f. Physiol., 
Leipzig, 1496, S. 372 ; Zuntz, ibid., S. 538, and Centralbl. f. Physiol., Leipzig u. Wien, 1896, 
S. 561; and Mosse, Arch. f. d. ges. Physiol., Bonn, 1896, Bd. lxiii. S. 613. Other papers by 
Seegen relating to this subject will be found in the Centralbl. f. Physiol., Leipzig u. Wien, 
during the last few years, and in the Arch. f. Physiol., Leipzig, 1895 and 1896. 


INFLUENCE OF ACTIVITY ON PROTEID METABOLISM. 915 


difference in the amount of sugar of the blood passing to and from an 
active muscle has been obtained by Chauveau and Kaufmann ;! such 
differences as are found generally fall within the limits of experimental 
error. Chauveau? has further endeavoured to show that in dogs 
muscular work is not effected at all at the expense either of the 
proteids of the body or of the food; but, as I. Munk has pointed 
out, the results obtained cannot be accepted as conclusive.? That 
glycogen disappears both from the liver and from the muscles of 
dogs, and from the “surviving” excised muscles of the frog, con- 
comitantly with the production of muscular work,* is held to be an 
argument in favour of this work being done at the expense of this 
carbohydrate. Under certain circumstances, however, the glycogen of 
the muscles may be caused to entirely disappear, although they are still 
capable of performing a large amount of work, which must, under 
these circumstances, be otherwise derived, however probable it may 
be that under normal circumstances the oxidation of dextrose or 
glycogen plays an important part in its production. 

In support of the view that muscular energy may be largely derived 
from the oxidation of carbohydrate materials, it has been observed by 
Tiegel,> that the Japanese rickshaw runners consume rice in large 
quantities, and at frequent intervals, during their periods of work, 
whereas on off-days they live mainly on a flesh diet.® 


Pfliiger 7 kept a dog of 30 kilos. weight in equilibrium upon perfectly lean 
meat, containing a very large preponderance of proteids over non-proteids. 
When caused to pass from a condition of rest to hard work, it lost flesh if kept 
on the same diet, until it assumed a lower position of N-equilibrium, but main- 
tained or even added to its weight if the amount of flesh was increased 500 
grms. per diem; about 50 per cent. of the potential energy of the additional 
proteid appearing as work. If now, whilst in N-equilibrium on lean flesh, fat 
and carbohydrate were added to the diet, these were not utilised for the pro- 
duction of energy, but were stored as fat; hence, Pfliiger argues, the living 
tissue prefers to use the proteid, and only takes non-proteid if insufficient proteid 
is offered to it. It should, however, be pointed out that Pfliiger’s dog was, 
with its purely proteid diet, in a condition of extreme emaciation,® and the cir- 


1 Compt. rend. Acad. d. sc., Paris, 1887, tome civ. pp. 1126, 1352, and 1409. Similar 
results (disappearance of sugar from blood passing through active muscles) have been 
obtained by Morat and Dufourt (Arch. de physiol. norm. et path., Paris, 1892, p. 327), who 
also found a certain disappearance after the work, which they suppose due to glycogen stored. 

2 With Contejean, Compt. rend. Acad. d. sc., Paris, tome cxxii. pp. 429, 504. 

3 Verhandl. d. physiol. Gesellsch. zu Berlin, 8 Mai, in Arch. f. Physiol., Leipzig, 1896. 

40. Nasse, Arch. f. d. ges. Physiol., Bonn, 1869, Bd. ii.S. 97 ; also Weiss, Sitzuwngsb. d. k. 
Akad. d. Wissensch., Wien, 1876, Bd. Ixiv. S. 288; Marcuse, Arch. f. d. ges. Physiol., 
Bonn, 1886, Bd. xxxix. S. 425; Manché, Zischr. f. Biol., Miinchen, 1889, S. Bd. xxv. 
164 ; and ibid., 1877, Bd. xiv. S. 473. 

5 Tbid., 1883, Bd. xxxi. S. 607. 

® U. Mosso and Paoletti (Atti d. Accad. d. Lincei, Roma, 1893) and V. Harley 
(Proc. Roy. Soc. London, 1893, p. 480, and Journ. Physiol., Cambridge and London, 1894, 
vol. xv. p. 97) using the ergograph of A. Mosso, found that they could perform a greater 
amount of voluntary muscular work when a large amount of cane-sugar was added to the 
diet. Experiments of this nature are, however, liable to a psychical error, and, as a 
matter of fact, experiments by Langemeyer (with Stokvis) made upon different persons 
failed to give similar results (see discussion in Brit. Med. Jowrn., London, 1898, vol. ii. 
pp. 1280-1285). 

7 Arch. f. d. ges. Physiol., Bonn, 1891, Bd. 1. S. 98, and Bd. li. S. 317. 

8 It may be noted in this connection that the ‘‘ Banting cure” for obesity depends upon 
the principle of selecting a diet not necessarily insufficient, but consisting mainly of lean 
meat. As in the case of Pfliiger’s dog, the tissues under these conditions use up the body- 
fat, which thus becomes gradually reduced in amount. 


916 METABOLISM. 


cumstance of the fat and liver cells seizing upon non-proteid materials and storing 
them as fat and glycogen in an animal in this condition, is not surprising, 
and is quite compatible with the view that in a normally nourished animal, 
where they are in excess, the non-proteids are the main energy producers. 


The most probable view appears to be that muscle, lke other cells, 
although it can only actually build up its bioplasm out of proteid, is 
nevertheless able to produce muscular energy by oxidation—perhaps 
occurring outside the actual molecules of the bioplasm, but under their 
direct influence—of any or all the organic foodstuffs, and that this 
process is attended only by such small disintegration and loss of the 
proteid material of the bioplasm as is necessarily attendant upon its 
functional activity—a loss which is comparable to the wear and tear of 
the working parts of a machine as distinct from its consumption of fuel. 

As a matter of fact, it has been shown by Zuntz,? that in a dog, 
abundantly fed on a mixed diet and caused to produce external work, 
the amount of extra proteid used during the period of work was less 
than one-twentieth part of the amount the oxidation of which would 
have been necessary to account for the work done. Moreover, in in- 
anition it is the glycogen and fat of the body which is first drawn upon, 
and this both at rest and during work. When the same dog was made 
to work during fasting, the N- secretion rose only very slowly ; the 
work was almost entirely done on the non-proteids of the body. 

It may be remarked that muscular activity is always accompanied 
by a production of energy far in excess of that which is necessary for 
the performance of the external work done. ‘Thus it was found by 
Hanriot and Richet* that when work was done there was seven times 
as much CO, produced as would have been accounted for by the oxida- 
tion necessary to perform the work. The additional energy appears of 
course as heat. On the other hand, it has been doubted whether there 
is any production of heat in the total absence of muscular activity.* 


Hanriot and Richet found the CO, to increase in greater proportion than 
the oxygen absorbed, so that the respiratory quotient became larger. Severe 
muscular exercise is stated to increase both the phosphoric acid® and the 
sulphur of the urine ;® the former more in proportion than the increase of N 
which may occur ; the latter about in proportion to the increased N, and in 
the form of ordinary sulphates.’ Along with the increase of phosphoric acid, 
there is also an increased excretion of lime, indicating, according to I. Munk, 
destruction of bony tissue. 


METABOLISM OF CARBOHYDRATE. 


The formation of glycogen.—The carbohydrates of the food are 
mainly converted by digestion into maltose, which passes in the process 
of absorption and assimilation into dextrose, this being the only sugar 


1Cf. Noél Paton, Edin. Med. Journ., June 1895. Also Rep. Lab. Roy. Coll. Phys., 
Edin., 1891, vol. iii. 

* With Frentzel and Loeb, Arch. f. Physiol., Leipzig, 1894, S. 541 (Verhandi. d. 
physiol. Geselisch. zu Berlin). See also Speck, ibid., 1895, S. 465. 

3 «Travaux du laboratoire de Ch. Richet,” 1893, tome 1. 

4 Cf. on this subject Speck, Centralbl. f. "a. med. Wissensch., Berlin, 1889; also article 
‘* Animal Heat,” p. 840. 

> Klug and Olsavsky, Arch. f. d. ges. Physiol., Bonn, 1893, Bd. liv. S. 21. 

6 Beck and Benedikt, ibid., S. 27. 

7J7. Munk, Verhandl. d. physiol. Geselisch. zu Berlin, 5th April 1895 (in Arch. ft. 
Physiol., Leipzig). 


METABOLISM OF CARBOHYDRATE. 917 


which is unmistakably found in the circulating fluids and in the tissues 
of the body. The path of absorption of carbohydrates is the same as 
that of proteids,! the absorbed dextrose being taken up by the blood, 
conveyed by the portal vein to the liver, and there stored. The portal 
blood taken during digestion is, in fact, the only blood in the body in 
which it can be conclusively shown that normally there is an excess 
of sugar. If taken in the intervals of digestion, it contains the same 
amount of sugar (one to two parts per thousand) as any other sample 
of blood. 

The blood of the hepatic vein, on the other hand, although it is said 
to contain an excess of sugar in the intervals of absorption of foods 
containing carbohydrates (but vide infra, p. 925), does not, during the 
actual process of such absorption, contain nearly as much sugar as the 
blood of the portal vein; we must therefore assume that the sugar 
which is carried to the liver by the portal vein is arrested in that 
organ. As a matter of fact, it is found that the immediate result of 
the digestion and absorption of a meal containing much carbohydrate 
food is to promote a considerable accumulation of glycogen in the liver, 
and the same is found if in a fasting animal solution of dextrose is 
slowly injected into a vein of the mesentery,? or if dextrose is injected 
subcutaneously (in rabbits).2 The same is even found if blood contain- 
ing dextrose is perfused through the “surviving” liver of a dog.* The 
amount of glycogen in the liver (which would contain in man “at most 
150 grms. of this substance) ° is not sufficient to account for the storage 
of the whole of the carbohydrate which is absorbed from a meal con- 
taining much starch or sugar. A part of the absorbed carbohydrate, 
when it is in excess, must therefore pass through the liver into the 
general circulation. Here it is apparently taken up by the muscles, for 
in a well-nourished animal, especially one nourished upon mixed food, 
the muscles may contain as much as 1 per cent. or even more of 
glycogen. Although this is not by any means as large a proportion as 
may be contained in the liver itself,® the muscles may collectively hold 
as much as is present in the liver.’ Even, however, if we take into 
consideration the whole of the glycogen in the liver, that in the muscles, 
and that in other tissues in the body in which it might be stored, it will 
still be found that the whole of the carbohydrates of a meal which 
contains much of these substances is not represented in the body, 
either by the glycogen of the organs or by the sugar present in the 


1 See this Text-book, vol. i. pp. 432-436. 

2 Bernard, ‘‘ Lecons de physiol. expér.,”’ Paris, 1855. 

°G. Lusk (with Voit), Zischr. 7. Biol., Miinchen, 1892, S. 288. The ingestion or sub- 
cutaneous injection of levulose will also cause a production of glycogen; galactose and 
lactose do not (C. Voit, ree f. Biol., Miinchen, 1892, Bd. xxviii. S. 245). Kausch and Solin 
(Arch. f. exper. Path. Pharmakol., Leipzig, 1893, Bd. xxxi. S. 398) obtained positive 
results with lactose and salnatoues Cf. also Cremer, ibid., 1893, Bd. xxix. 8. 484; Haycraft, 
Ztschr. f. physiol. Chem., Strassburg, 1894, Bd. xix. S. 141. Whether the levulose is first 
converted into dextrose, ‘and this into glycogen, or whether the glycogen is formed directly 
from levulose, the ketone group of levulose must in either case become converted into an 
aldehyde group (Neumeister, ‘‘ Lehrbuch,” Aufl. 2, S. 326). On the subject of the forma- 
tion of glycogen from carbohydrates, see further, E. Voit, Zischr. f. Biol., Miinchen, 1889, 
Bd. xxv. 8. 551; C. Voit, ibid., 1892, Bd. xxviii. 

a Luchsinger, Tnaug. Diss., Zurich, 1875. 

> Bunge, ‘* Lectures,” p. 383. 

S Pavy found in rabbits and dogs fed with a large amount of carbohydrate-containing 
food, that the amount of glycogen of the liver might - rise as high as 17 per cent. (‘* Physio- 
lozy of Carbohydrates,” p. 116). 

7 Bohm, Arch. f. d. ges. Physiol., Bonn, 1880, Bd. xxiii. 8. 51. 


918 METABOLISM. 


circulating fluid. The amount which is not accounted for may possibly 
pass into the constitution of the proteids and nucleo-proteids, and also 
of those albuminoids from which a carbohydrate material has been 
obtained on decomposition with acids, and it may be that the excess is 
in this way stored until required. In the embryo, glycogen is much 
more widely distributed and occurs in much larger proportion than 
after birth, especially in the developing muscles; at this time the liver 
may contain very little. It occurs also in considerable amount in the 
placenta. 

The glycogen, both of the liver and of the muscles, gradually dis- 
appears in starvation, and first from the liver.t| The disappearance is 
accelerated by muscular work,” and in warm-blooded animals by external 
cold;% it is probable, therefore, that the glycogen is used for the pro- 
duction of both work and heat. The rate at which it disappears in 
starvation varies greatly in different animals. Aldehoff found it in large 
quantity in the muscles of a horse which had fasted for nine days; 
in dogs it may be found after three weeks, and has been detected 
after thirty-five days’ fasting;* in rabbits it has disappeared usually 
within a week. In frogs it accumulates in the liver towards the 
end of the summer, and gradually disappears during the winter; 
but even if they take no food, there is still some present at the end 
of the winter, but more in the muscles than in the liver. The same 
is the case with hibernating animals (Voit). On the other hand, if 
carbohydrates are given to animals deprived of their glycogen by 
starvation, this substance very rapidly reappears in the muscles and 
liver.° 


The diminution of the glycogen of the muscles, concomitantly with their 
activity, has been already referred to in connection with muscular metabolism 
(p. 915). In the passage of excised muscles into the condition of rigor mortis 
there is a certain amount of disappearance, amounting, according to Werther,® 
to as much as 50 per cent. of the original amount, but far less than as the 
result of tetanising the muscles. In either case, what becomes of it is not 
clear; the sarcolactic acid which makes its appearance is not derived from it; 
the formation of the acid is not dependent upon the presence or absence of 
glycogen. If rigor is allowed to come on in the cold, the acid still appears, but 
there is no appreciable disappearance of glycogen.’ On cutting the nerve pro- 
ceeding to a muscle, the glycogen becomes increased in quantity.§ The increase 
proceeds up to the fourth day. Section of the tendon of a muscle has a 
similar effect.® 

According to the observations of Kiilz, glycogen begins to appear in the liver 


1 Aldehoff, Ztschr. f. Biol., Miinchen, 1889, Bd. xxv. S. 137 ; Hergenhahn, ibéd., 1890, 
Bd. xxvi. S. 225. 

2Manché, Zischr. f. Biol., Miinchen, 1889, Bd. xxv. S. 163. The glycogen of muscles 
disappears after a period of tetanus, and also in frogs poisoned by strychnia, but not in 
the muscles of a leg the sciatic nerve of which has previously been cut. 

3 Kiilz, Arch. f. d. ges. Physiol., Bonn, 1881, Bd. xxiv. 5.46. In cold-blooded animals 
external warmth produces the disappearance of glycogen from the liver (Langley). 

4 Quinquand, Compt. rend. Soc. de biol., Paris, 1886, p. 285. 

5 For references, see Bunge, ‘‘ Lectures,” pp. 383-385. See also Langley, Proc. Roy. 
Soe. London, 1882, vol. xxxiv. p. 22 (histological observations) ; Quinquand, Compt. rend. 
Soc. de biol., Paris, 1889, p. 285; Deweyre, ibid., 1892, No. 19. 

6 Arch. f. d. ges. Physiol., Bonn, 1890, Bd. xlvi. 8, 63. 

7 Bohm, zbid., 1880, Bd. xxiii. S. 44. 

8 Bernard, Compt. rend. Acad. d. sc., Paris, 1859, tome xlvili. p. 683. 

® Boldt, Diss., Wiirzburg, 1893; Vay, Arch. f. exper. Path, wu. Pharmakol., Leipzig, 
1894, Bd. xxxiv. S. 45. 


FORMATION OF GLYCOGEN. 919 


of starved rabbits two to four hours after a meal containing carbohydrates, and 
disappears after five to eight hours’ hard muscular work (dog). It is formed 
in the muscles of a frog which has been deprived of its liver ;! and may be 
increased in muscular tissue by perfusing blood, to which grape-sugar has been 
added, through the vessels of the muscle.” 


The formation of glycogen from other than carbohydrate material. 
—That glycogen can be formed in the entire absence of carbohydrate 
material from the food, is shown by the fact that animals which have 
been for a long time fed on lean meat, deprived as much as possible of 
carbohydrate, are found to have even considerable amounts of glycogen 
in their liver and muscles. Indeed, if an animal be allowed to fast 
for some days, and to perform also severe muscular work,—circum- 
stances under which practically the whole of the glycogen can be made 
to disappear both from the liver and muscles,—on now administering 
proteid® or gelatin* food, altogether free from carbohydrates, glycogen 
will reappear both in the liver and in the muscles. Even without the 
administration of food, by the employment of narcotic drugs, such as 
chloral, which tend to diminish or arrest muscular activity, glycogen 
will reappear ;° in this case it must be formed from the proteids of the 
body. The administration of fat without proteid does not cause such 
reappearance, nor does the addition of fat to the food, even in consider- 
able excess, increase the amount of glycogen in the liver. Arsenic 
poisoning causes a diminution in the glycogen both of the liver and of 
the muscles; probably by impairing the vitality of their bioplasm. On the 
other hand, the administration of glycerin promotes the storage of gly- 
cogen in the liver ;? it acts, however, apparently rather by preventing the 
removal of the glycogen, than by becoming itself converted imto that 
substance, or than by its becoming itself oxidized and thus acting as a 
glycogen sparer (Ransom). Thus it is found that with glycerin adminis- 
tration the sugar puncture is not able to produce glycosuria. 


The administration of ammonium carbonate was also found by Réhmann § 
to promote the accumulation of glycogen in the liver, and this property is 
shared by many ammonium compounds,’ but how they may act has not as yet 


1 Kiilz, Arch. f. d. ges. Physiol., Bonn, 1881, Bd. xxiv. S. 64. This volume contains 
several other papers by Kiilz on the conditions of formation of glycogen. 

2 Kiilz, Zschr. f. Biol., Mimmchen, 1891, Bd. xxvii. S. 237: there was, however, 
only an increase in three out of eleven experiments. 

3Naunyn, Arch. f. exper. Path. u. Pharmakol., Leipzig, 1875, Bd. iii. S. 94; v. 
Mering, Arch. f. d. ges. Physiol., Bonn, 1876, Bd. xiv. S. 281; Kiilz, Punfzigj. Doct.- 
Jubelf.d. .. . Carl Ludwig, Marburg, 1890. 

4 Salomon, Virchow’s Archiv, 1874, Bd. lxi. S. 352 ; Luchsinger, Inaug. Diss., Zurich, 
1875 ; v. Mering, Joc. cit. 

5 Zuntz u. Vogelius (Arch. f. Physiol., Leipzig, 1893, S. 378, Verhandl. d. physiol. 
Gesellsch. zu Berlin) obtained a reappearance of glycogen on administering chloral to 
starved and strychnised rabbits. 

6 Chauveau has come to the conclusion that carbohydrate may be formed from fat in 
the animal body (Compt. rend. Acad. d. sc., Paris, 1887, tome cxxii. p. 1098), and Seegen, 
‘Die Zuckerbildung,” also holds this view, but the evidence in its favour appears to be very 
insufiicient. 

7 Weiss, Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1878, Bd. xvii. 8. 13; Eckhard, 
loc. cit. ; Luchsinger, Inaug. Diss., Zurich, 1875 ; W. Ransom, Journ. Physiol., Cambridge 
ae London, 1887, vol. viii. p. 99 ; Schenck, Arch. f. d. ges. Physiol., Bonn, 1894, Bd. 
vil. S. 569. 

8 Arch. f. d. ges. Physiol., Bonn, 1886, Bd. xxxix. S. 21. Cf. also Kulz (Funfzig). 
Doct.-Jubelf. d. . . . Carl Ludwig, Marburg, 1820), who found that urea as well as 
ammonia salts increased the glycogen of the liver. 

9 Nebelthau, Ztschr. f. Biol., Miinchen, 1892, Bd. xxviii. S. 188. 


920 METABOLISM. 


been determined. Bicarbonate of soda is stated by Dufourt to have the effect 
of increasing the amount of glycogen in the liver. Dufourt’s experiments 
were made upon dogs on a flesh diet after a period of fasting.t 


Glycogen becomes formed in the embryo chick in considerable 
amount, although there is very little glycogen or carbohydrate at all 
in the egg. Here also it must in all pr obability be formed from proteid. 
Glycogen can only be supposed to be produced from proteids in the 
animal body by a process of synthesis, preceded by a breaking down of 
the proteid molecule.? It is highly probable that dextrose is a stage in 
the course of such synthesis; and since dextrose is constantly found in 
the blood, even in prolonged inanition, it may well be inquired whether 
the carbohydrate of the body is invariably converted into glycogen, 
prior to being employed by the tissues for the production of energy. 
Under certain circumstances it appears clear that the synthesis of 
carbohydrate never passes beyond the stage of dextrose. Thus, in the 
diabetes produced by successive doses of “phloridzin there may be no 
glycogen whatever in the liver and muscles, and yet within the proteid- 
fed and in the fasting animal large quantities of dextrose are formed 
and eliminated with the urine. 

Phloridzin is a glucoside obtained from the root-bark of certain 
trees (apple and cherry), but it does not act by virtue of its glucose 
group, for the same action is got by the employment of the non-glucoside 
phloretin which is obtained from phloridzin. If injected under the 
skin, or taken into the alimentary canal, either phloridzin or phloretin 
produces within a very short time the appearance of sugar in the urine, 
and this appearance of sugar in the urine is accompanied by a diminution 
of the liver glycogen. The glycogen in the liver does not, however, 
completely disappear as the result of a single dose of phloridzin; both in 
that organ and in the muscles a certain amount remains, but if a second 
dose of phloridzin is given, glycosuria is again produced, and by repeating 
the administration once or twice the glycogen can be completely removed 
from the liver. Each successive dose of phloridzin will, however, cause 
a fresh appearance of sugar in the urine even after complete removal of 
glycogen from the liver, which shows that, although part of the sugar 
which has appeared in consequence of the action of phloridzin may have 
been produced from the glycogen in the liver, a part must be produced 
in some other way. As by the employment of successive doses of this 
drug all the appreciable glycogen in the body can be got rid of,* it is 
almost certain that the sugar which then appears is derived from the 
metabolism of proteid; and this is rendered the more likely since it is 


1 Arch. de méd. expér. et d’anat. path., Paris, 1890, tome ii. p. 424. 

* Cf. Pfliiger, Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xlii. S. 144. 

Biv, Mering, Verhandl. d. Cong. f. innere Med. Wiesbaden, 1887, S. 349 ; Zischr. f. klin. 
Med., Berlin, - 1888, Bd. xiv. S. 405; 1889, Bd. xvi. S. 431, See also on phloridzin 
diabetes, Cremer and Ritter, Zéschr. f. Biol., Miinchen, 1892, Bd. xviii. S. 459, and Bd. 
xix. S. 256; and Praussnitz, ibid. S. 168. 

4 Kiilz and Wright (Zéschr. f. Biol., Miinchen, 1891, Bd. xxvii.) have shown that the 
glycogen is not so readily got rid of as V. Mering supposed, and that as a matter of fact 
there may still have been some glycogen left in the animals employed by v. Mering. These 
authors state that phloridzin does not produce glycosuria in frogs. It did, however, 
produce glycosuria i in birds (v. Mering, Verhandi. d. Co ong. We innere Med., Wiesbaden, 1887), 
in which pancreatic extirpation failed to cause glycosuria ; it also increases the amount of 
sugar in the urine of animals suffering from pancreatic diabetes (Minkowski, Arch. f. exper. 
Path. 1. Pharmakol., Leipzig, 1893, ‘Bd. xxxi. 8. 148) ; and, further, Cremer has obtained 
phloridzin diabetes in frogs by taking special measures to ensure the action of the drug 
(Zischr. f. Biol., Miinchen, 1892-3, Bd, xxix, S. 175). 


FORMATION OF GLYCOGEN. g21 


noticed that the amount of nitrogen in the urine goes hand in hand with 
the amount of sugar excreted.! F urther, it 1s found that if the elycogen 
in the body be reduced as much as possible by a prolonged period of 
starvation, followed by excessive muscular action, such as is caused by a 
dose of strychnine, the administration of phloridzin will still cause 
glycosuria; much more sugar appearing under these circumstances in 
the urine than can be accounted for by any glycogen which might remain 
either in the liver or any other tissues of the ‘body. It seems, therefore, 
clear that the sugar must have been derived from proteid; in this case 
the proteids of the body itself. It may further be mentioned that Pick? 
has found that if the liver be rendered functionless by injecting dilute 
sulphuric acid into the bile ducts, its glycogen disappears in twelve 

hours, but phloridzin still produces glycosuria, although other agents 
which usually cause glycosuria, such as carbon monoxide, fail to produce 
this effect. As with the glycosuria produced by phloridzin, so also with 
severe cases of natural diabetes in man, there appears to be no doubt 
that a direct formation of sugar from proteid may occur without any 
formation of glycogen. It may be supposed with some probability that 
such a direct formation of sugar (mainly by the liver, for phloridzin 
diabetes is produced in the absence of the liver),> but also by other organs; * 
and its passage into the blood may occur to some extent normally ; that 
in fact a part of the carbohydrate produced from proteid may be at 
once passed into the blood in the form of dextrose, and a part further 
synthetised into glycogen and stored as such.’ We might then explain 
phloridzin diabetes, and possibly certain severe cases of natural diabetes, 
by supposing that the further synthesis into glycogen is In some way 
interfered with, so that an excess of the carbohydrate formed is passed 
into the blood in the form of sugar. 


It must, however, be stated that the production of the severest forms 
of diabetes above mentioned, and also that produced by removal of the 
pancreas (see p. 927) and by the sugar-puncture (see p. 926), is still excced- 
ingly obscure. According to y. Mering and most other observers, there 
is a fundamental difference between the diabetes caused by phloridzin 
and that produced by pancreatic removal or sugar-puncture, in that in 
the former there is. no excess of sugar in the blood,—in fact the amount 
may be less than normal,°—whereas in the two last-mentioned forms the 


v. Mering, doc. cit., found the proportion of urea to sugar in phloridzin diabetes=1 : 2, 
in cases of natural diabetes=1 : 1. See also Moritz and Praussnitz, Zischr. f. Biol., 
Miinchen, 1891, Bd. xxvii. S. 81; Praussnitz, Joe. cit.; Cremer and Ritter, Ztschr. f. Biol., 
Miinchen, 1893, Bd. xxix. S. 256. v. Mering and Minkowski (Arch. ee exper. Path. u. 
Pharmakol., Leipzig, 1889, Bd. xxvi.) found ‘the proportion of sugar to nitrogen =3: 1 in 
pancr eatic diabetes. 

2 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1894, Bd. xxxiii. S. 305. 

3 Thiel, Arch. f. exper. Path. u. Pharmakol. , Leipzig, 1887, Bd. xxiii. 

4 Cornevin (Compt. rend. Acad. d. sc., Paris, 1895, tome cxvi. p. 263) has shown that 
phloridzin causes a marked increase in the amount of sugar eliminated in the milk. 

° Seegen states that he obtained a formation of sugar (in excess of that produced by 
transformation of any glycogen present) in a mixture of “chopped liver and arterial blood, to 
which peptone had been added, and even with the addition of fat in place of peptone. 
But his results have not been confirmed by other workers. Cf. Bohm u. Hoffmann, 
Arch. f. d. ges. Physiol., Bonn, 1880, Bd. xxiii.; Girard, ibid., Bd. xvi. S. 294; 
Neumeister, Zéschr. f. Biol., Miinchen, 1890, S. 346. The possibility of the formation of 
carbohydrate from fat in "animals, ‘although not experimentally proved, must not be 
ignored. For there is clear evidence that such a transformation may occur in germinating 
seeds of plants (Sachs, ‘‘Text-Book of Botany,” transl. by Bennett and Thiselton Dyer, 
1875, p. 638), and if plant bioplasm is capable of effecting the transformation, animal 
bioplasm might also be expected to have a similar power. 

© No diminution but an increase in the amount of blood-sugar was found by Pavy to 


922 METABOLISM. 


percentage of sugar in the blood is greatly increased. This seems to point to 
the fact that phloridzin, besides any action it may have upon the metabolism 
of carbohydrate in the liver and muscles, increases the permeability of the 
kidney tubules to sugar, or causes the epithelium of the tubules to be more 
susceptible to the presence of sugar in the blood, so that the kidney removes 
sugar from that fluid more rapidly than under normal circumstances, and thus 
the percentage is even diminished below normal! On the other hand, the 
diminution in the percentage caused by such removal, even if it were in- 
appreciable to chemical methods of analysis, might be supposed to excite the 
sugar-producing tissues to increased activity, thus adding constantly more sugar 
to the blood, to be again removed by the kidneys, and so on in a vicious circle. 
On the other hand, Levene? has given reasons for believing that the 
sugar in phloridzin diabetes may be produced in the kidneys, a view which 
was previously expressed by Uschinsky (quoted by Levene). Thus, after 
trying the renal blood vessels and then injecting phloridzin, there was no 
accumulation of sugar in the blood ; indeed, the percentage of sugar in that 
fluid was, if anything, diminished. Minkowski* had previously failed to find 
an increase above the normal after ablation of the kidneys and injection of 
phloridzin, and Schabad+* obtained analogous results after tying the ureters. 
Levene also finds that the amount of sugar in the kidneys is increased as the 
result of giving phloridzin, and that under the same circumstances there is 
rather more sugar in the blood of the renal vein than in that of the corre- 
sponding artery. He admits, however, the probability that it is formed in 
other organs as well as in the kidney. Minkowski® has put forward the 
suggestion that phloridzin becomes split up in the kidney into phloretin and 
sugar ; the latter becoming eliminated, and the former combining again with 
sugar in the organism, and then again yielding this to the kidney, and so on. 


Glycogenesis—- Theory of Bernard—As regards the fate of 
the carbohydrates of the food, there is no doubt that, whether they 
inevitably go through the stage of glycogen or not, they ultimately 
undergo oxidation into carbon dioxide, and removal in the form of this 
substance and water. The carbohydrate of the food directly creases 
the amount of carbon dioxide given off, and in proportion to the amount 
of such.food taken. This elimination of carbon dioxide is not immediate, 
for most of the carbohydrate taken in is in the first instance stored, 
and only becomes oxidised gradually, as the needs of the organism 
demand. The view which has been most commonly held with regard to 
the method of transformation of the stored carbohydrate into the 
products of its oxidation, originated with Bernard. Having found that 
the blood of the hepatic vein constantly contains more sugar than 
the blood of the portal vein, except during the absorption of food, 
he concluded that the glycogen which he had discovered in the 
liver,® and which is no doubt the chief store of carbohydrate material in 
occur in cats to which phloridzin had been administered (‘‘ Proc. Physiol. Soc.,” Noy. 14, 
1896, Journ. Physiol., Cambridge and London, vol. xx.), and he therefore denies that 
diminished glycemia is a feature of this form of diabetes. 

1 vy. Mering, Joc. cit. ; Minkowski, ‘“‘ Untersuch. ii. d. Diabetes mellitus,” Leipzig, 1893 ; 
Zuntz, Arch. f. Physiol., Leipzig, 1895, S. 570. 


2 Journ. Physiol., Cambridge and London, 1894-95, vol. xvii. p. 259. 

3 Loc. cit. 

4 Vrach., St. Petersburg, 1892, No. 49, quoted from Minkowski. 

SOp-weit-5e pil 52: 

6The fact that sugar is formed in the liver was discovered by Bernard in 1848 
(Compt. rend. Acad. d. sc., Paris, 1848, tome xxvii. pp. 249, 253, 514; ‘‘ Nouvelle fonction 
du foie, etc.,” Paris, 1853), but the substance (glycogen), from which it is produced was 
not found until 1857 (by Bernard, and also independently by Hensen). For a full list of 
Bernard’s writings on this subject, see ‘‘ L’ceuvre de Claude Bernard,” Paris, 1881. 


GL YCOGENESIS— THEORY OF BERNARD. 923 


the body, gives off such material into the blood in the form of dextrose. 
This dextrose is taken to the tissues and is used by them, becoming 
oxidised within them. Whether this oxidation occurs outside the actual 
bioplasm, or whether the dextrose which is taken to the bioplasm 
becomes first of all built up into its molecules and then split up 
and oxidised, and whether the products of its oxidation leave the 
muscles in their ultimate forms, are questions which we need not 
now consider. In either case the effect of such oxidation is to produce 
energy (in the form of heat and mechanical work). 


This view of Bernard’s has, on the whole, met with general favour among 
physiologists. Some there are, indeed, who have so far proceeded beyond 
Bernard, as to assert that the whole energy of the body is derived from the 
oxidation of carbohydrate. Such carbohydrate, which is taken to the tissues 
in the blood in the form of glucose, is assumed to be formed either from the 
stored carbohydrate of the liver, as Bernard supposed, or independently of this 
from proteid, or even from fatty materials in the liver cells, and being carried 
to the tissues to be taken up by them, oxidised within them, and thus become 
the immediate source of the energy of the body, whether this takes the 
form of heat or work. It is in fact assumed that the main result of 
metabolism within the body is the production in one part, and the destruction 
in another, of carbohydrate. Such a view has been chiefly contended for by 
Seegen ! and Chauveau, who hold that even the proteid material of the food, 
at least its non-nitrogenous part, must ultimately become converted into 
carbohydrate before it can become oxidised in the tissues (see p. 914). 

It is obvious that Bernard’s theory is, in the main, dependent upon the 
circumstance that sugar is continually being passed from the liver into the 
hepatic blood, even during starvation, and this, in fact, has been directly 
affirmed by Bernard and others. Even in the fasting animal, sugar is found in 
the blood, except at the extreme end of an inanition period ; and, according to 
the analyses of Seegen, it always occurs in larger amount in the hepatic blood, 
whatever be the nature of the food, whether proteid, fat, or carbohydrate, 
than in blood from any other source. This occurrence of dextrose in 
larger proportion in the hepatic blood than in the rest of the blood of the 
body, if it were completely and satisfactorily determined, would be a fact of 
fundamental importance, and would go very far to establish Bernard’s theory 
upon a firm basis. But there are reasons for believing that such an excess of 
sugar as has been found by Seegen and other observers is not present 
under absolutely normal conditions. Seegen’s experiments were made without 
anesthetics, and it is a well-established fact that any operation upon an 
animal, which involves the production of pain, will immediately produce 
a transformation of the glycogen of the liver into sugar, and the appearance of 
an excess of sugar in the hepatic blood.? It is, in fact, admitted by Seegen 


1<*Pie Zuckerbildung im Thierkorper,” Berlin, 1890, S. 218, and numerous papers in 
the Arch. f. d. ges. Physiol., Bonn, and in the Centralbl. f. Physiol., Leipzig u. Wien. 

2 Seegen calculates that in man from 500 to 1000 grms. of dextrose nay pass into 
the blood from the liver in twenty-four hours. But since his calculations are based upon 
experiments made upon animals in an abnormal condition so far as the carbohydrate 
metabolism is concerned, these numbers cannot be accepted. Cf. Abeles, Med. Jahrb., 
Wien, 1886, S. 383; I. Munk, Berl. klin. Wehnschr., 1890, S. 595; also Pfliiger, 
Arch. f. d. ges. Physiol., Bonn, 1891, Bd. 1. S. 330, 396 ; Mosse, zbid., 1896, Bd. lxiii. S. 
613; Zuntz, Centralbl. f. Physiol., Leipzig u. Wien, 1896, S. 561. The blood is obtained 
either directly from one of the hepatic veins, or by passing a catheter up into the inferior 
cava, this vein being then blocked just below the reception of the hepatic veins by the 
inflation of an india-rubber bag ; or a tube is passed down from the jugular vein through 
the right auricle into the inferior cava, and its bent end is made to enter one of the 
hepatic veins, 


924 METABOLISM. 


himself, that when the blood from the hepatic vein is collected under 
conditions of anesthesia, the difference between the percentage amount of 
sugar in the hepatic blood and that in ordinary arterial blood becomes 
greatly diminished, if it does not altogether disappear.! 


Bernard’s views have been combated strenuously by Pavy,? whose 
method of experimentation is not open to the same objection as that 
of Seegen and others who have found a constant excess of sugar in 
the hepatic blood. Pavy takes blood from the animal immediately 
after it has been killed by a blow upon the head, and before there _ 
has been time for any change to have occurred in the liver, and he 
finds that blood which is collected under these circumstances from 
the inferior vena cava (including, therefore, the blood which has passed 
out from the liver) never shows any appreciable excess of reducing 
substances over blood obtained from other parts of the body. Results 
similar to those of Pavy have also been obtained, although under 
somewhat different conditions, by other observers. 

We are therefore landed in this difficulty, as the result of the 
imperfection of our present methods, that we cannot be sure whether 
the blood of the hepatic vein does or does not, normally, contain an 
excess of sugar. If it does, we are bound to assume that sugar is 
being continually passed off from the liver into the general blood of the 
body, and since this sugar does not pass off by the urine, it can only be 
available for the nutrition of the tissues, and the production of energy 
by oxidation. If sugar does not pass from the liver into the blood, we 
should require to find some form in which the glycogen, which is 
undoubtedly stored up in the liver, is got rid of, and also to find some 
meaning for its presence there and in the muscles. 

It has been suggested by Pavy? that such stored glycogen may 
become converted into fat. There is no doubt that carbohydrate 
food does become converted in the body into fat, and there are 
many instances of the formation of fat from carbohydrate material in 
plants; it is therefore not altogether wanting in probability, that the 
glycogen which is stored up in the liver cells and muscles may also 
become converted into fat. Such fat may be assumed to be gradually 
removed by the blood and carried to the different organs, and in them 
ultimately oxidised to carbonic acid and water. 

Another supposition, which we have already considered, is that it 
becomes directly oxidised, and produces heat. As most of the 
oxidation of the body occurs in the muscles, and as the muscles retain 
their glycogen in starvation longer than the liver, although the latter 
organ contains normally a much larger proportion, it seems very 
probable that the glycogen passes from the liver to the muscles. This 
cannot be as glycogen, for gly cogen is not present in blood plasma, and 


1 Centralbl. f. Physiol., Leipzig u. Wien, 1896- 97, Bd. x. S. 497, 822. 

aco he Physiology of the Carbohydrates,” London, 1894. Here other papers by the 
same author are referred to. 

* Ibid., pp. 245 to 252. In connection with the question of sugar production by the 
liver, it may be mentioned that removal of this organ or cutting ‘off its blood supply in 
rabbits (Bock and Hoffmann, ‘‘ Exper. Studien ti. Diabetes,” Berlin, 1874), dogs (Seegen, 
“Die Zuckerbildung,” and Tanyl and v. Harley, Avch. f. d. ges. "Physiol., Bonn, 1895, 
Bd. Ixi. S. 551), geese (Minkowski, Arch. f. exper. Path. u. Pharmakol., Leipzig, 1882, 
oe ae S. 41), is followed by either disappearance or marked diminution of the sugar of the 

ood. 


GLYCOGENESIS—THEORY OF BERNARD. 925 


what little there is in the blood is in the white corpuscles—a property 
they share with most other protoplasmic structures. It is therefore 
natural to conclude, even if we cannot show the fact conclusively 
by analysis, that it passes from the liver to the muscles in the form of 
grape-sugar. The extra amount of sugar in the hepatic blood might be 
so small as easily to fall within the limits of experimental error, and 
yet suflicient to transport a very large amount of carbohydrate in the 
course of twenty-four hours.t Nor can it be said that we have any 
means of exactly estimating the amount of sugar in the blood at all. 
What has been estimated hitherto in the blood is not sugar alone, but 
substances which reduce cupric salts. That a part of these substances 
consists of glucose, is shown by the reaction with phenylhydrazine. 
But it must not be forgotten that there occur in the blood other 
substances which, although not glucose, also reduce metallic salts ; nor 
can we say what proportion these hold to the glucose in the blood. 
Hence any mere determinations of the reducing substances do not give 
us a direct measure of the amount of glucose, and it is impossible to 
admit as proven any theory which is entirely built up upon observations 
of the amount of reduction yielded by the blood, on the assumption that 
such reduction is exclusively produced by glucose. If, therefore, we 
accept Bernard’s theory, it must be understood that the evidence in its 
favour is mainly of an indirect character. There exists an analogy in 
the case of plants, in which the stored insoluble carbohydrate (starch) is 
conveyed from one part to another in the form of soluble sugars. And 
it must further be looked upon as a powerful argument in favour of 
Bernard’s hypothesis, that under certain circumstances there is rapidly 
produced a very appreciable transformation of the liver glycogen into 
dextrose. This occurs as the result of stimulation of almost any sensory 
nerve, as the result of interference with the hepatic circulation,? and as 
the result of administration of many drugs. And it also occurs, as was 
found by Bernard early in his investigation of the subject, very rapidly 
after death, especially if the liver be kept at the body temperature. On 
the other hand, this transformation can be prevented by subjecting the 
liver, immediately after the animal is killed, to a sufficient amount of 
heat, as by throwing it in pieces into boiling water, or of cold, as by 
ice-cold salt solution,? or by a freezing mixture* It has been held 
that this transformation, which occurs during the “survival” of the 
liver cells, is due to a continuance of such chemical processes as occur 
in the cells during life, and which lead to the change of their glycogen 
into sugar, just as the chemical changes which occur in muscle which is 
passing into rigor are generally similar to those produced during the 

1 Foster, ‘‘ Text-Book of Physiology,” 1889, pt. 2, 5th edition, p. 726. 

2 For these reasons conclusions should be drawn very cautiously from such experiments 
as those of the brothers Cavazzani (Centralbl. f. Physiol., Leipzig u. Wien, 1894, Bd. viii. 
S. 33), who obtained disappearance of glycogen in the liver, and increase of sugar in the 
hepatic blood, on stimulation of the celiac plexus. The same remark applies to the results 
obtained by Morat and Dufourt by excitation of the vagus (Arch. de physiol. norm. et path., 
Paris, 1894, pp. 631 and 371). 

3 Dastre states that a temperature of 55° C. is sufficient to destroy the amylolytic action, 
and that prolonged exposure to ice-cold salt solution has the same effect. He argues 
from this that the action is not that of a ferment, but of cell protoplasm (Arch. de physiol. 
norm. et path., Paris, 1888, p. 69). On the other hand, Nasse found that liver digested 
with chloroform water has a free amylolytic action, which must in that case be due toa 
ferment (Rostocker Zig., 1889, No. 105). See also Salkowski, Centralbl. f. d. med. 


Wissensch., Berlin, 1889, No. 13). 
4 Payy, ‘‘ Physiology of Carbohydrates,” p. 134. 


926 METABOLISM. 


activity of the muscular tissue; and accordingly anything, such as the 
sudden application of heat, able to instantly kill the liver cells stops 
such change On the other hand, it may also be that the trans- 
formation is caused by an amylolytic ferment, which is produced by 
the cells. This view was in fact held by Bernard” but he afterwards 
supposed that the ferment was derived from the blood.’ 


It has been denied that such a ferment can be obtained from the liver, and 
it has therefore been contended that the transformation of glycogen into sugar 
must be produced by the direct metabolic action of the cell protoplasm. It 
has also been argued that, since the sugar which is produced by the digestive 
amylolytic ferments is maltose, and not dextrose, the production of dextrose in 
the surviving liver cannot be due to a ferment. Pavy, however, has shown 
that an active amylolytic ferment is obtainable from the alcohol hardened 
liver both in rabbits and cats, and that the sugar which is produced by it is 
closely similar to, if not identical with, that formed in the “surviving ” organ.* 
A ferment converting glycogen into dextrose has also been obtained from 
the liver by Arthus and Huber,® and by Bial,®° who states that it is identical 
with and probably derived from the diastatic ferment of blood and lymph.’ 


Puncture diabetes.—Bernard § also discovered the fact that certain 
lesions of the central nervous system, and especially a puncture in the 
region of the floor of the fourth ventricle, which corresponds, as we now 
know, very nearly to the position of the vasomotor centre, produces a con- 
dition of glycosuria ; and that this is caused by a transformation of the 
glycogen of the liver into sugar, which is then taken up by the hepatic 
veins in so considerable a quantity, and increases so much the percentage 
of sugar in the blood, as to cause its excretion by the kidney. That this 
is the origin of the sugar in the so-called “ puncture diabetes,” is proved 
by the fact that, if precautions are taken to render the liver devoid of 
glycogen, as by a prolonged period of inanition,® with or without severe 
muscular activity, the glycosuria ordinarily resulting from puncture of 
the fourth ventricle does not appear, nor does it occur im frogs with the 
liver removed. It has been conjectured, with much probability, that 


1 Noél Paton found that if the liver substance be bruised up in a mortar with sand, so as 
to crush and thus destroy the liver cells, the change of glycogen into sugar does not occur 
(Phil. Trans., London, 1894, vol. clxxxi. p. 233). But a repetition of his experiments by 
Pavy (‘‘Epicriticism,” London, 1895, p. 79) has not yielded the same results, and, since 
they were only few in number, they can hardly be accepted without further confirmation. 
Paton has, moreover, in later experiments, himself failed to verify his earlier results 
(Journ. Physiol., Cambridge and London, 1897, vol. xxii. p. 121). 

2 «<Tecons sur le diabete,” Paris, 1877. 

3 Compt. rend. Acad. d. sc., Paris, tome xli. p. 461. 

4There seems to be little doubt that this sugar is mainly if not entirely dextrose 
(Seegen and Kratschmer, Arch. f. d. ges. Physiol., Bonn, 1880, Bd. xxii. S. 214), but 
according to Chittenden and Lambert (Stud. Lab. Physiol. Chem., New Haven, 1885) 
there is some maltose. Kiilz and Vogel also found a certain amount of both maltose 
and isomaltose in the fresh liver (Centralbl. f. d. med. Wissensch., Berlin, 1894, S. 769). 
The remark that has been already made regarding the sugar found in blood applies to all 
these determinations of liver sugar, namely, that what is actually determined is the 
amount of reduction of cupric oxide, and that there may be, and undoubtedly are, other 
substances present besides sugar which effect this reduction. 

5 Arch. de physiol. norm. et path., Paris, 1892, p. 651. 

6 Arch. f. d. ges. Physiol., Bonn, 1893, Bd. lv. S. 434. 

7 See article ‘‘ Blood,” p. 160. 

8 “Tecons sur la physiol. et la pathol. du systtme nerveux,” Paris, 1858, tome i. p. 
401. See also Eckhard, Beitr. z. Anat. u. Physiol. (Eckhard), Giessen, 1869, Bd. iv. 8. i. 
Kiihne found the same thing to happen in frogs (Inaug. Diss., Gottingen, 1856). 

® Luchsinger, oc. cit. 


PUNCTURE DIABETES. 927 


the condition of the liver which results from such puncture, and which 
tends to cause this transformation of the glycogen into sugar, is due to 
a disturbance of the hepatic circulation, and especially of the circula- 
tion in the hepatic artery, thus indirectly producing an alteration in the 
normal metabolism of the organ; but this cannot be considered as con- 
clusively proved, and it may be due to a direct interference with the 
action of the nerves to the liver cells. Diabetes does not, however, 
occur on section of the splanchnic nerves alone.’ But in all probability 
the vasomotor centre is stimulated by the puncture, for other forms of 
stimulation of the vasomotor centre also tend to produce a temporary 
diabetes, such as the prolonged stimulation? of most sensory or afferent 
nerves (e.g. the sciatic, the central end of the vagus, and the depressor *), 
which are known so to influence the vasomotor centre as to produce 
constriction or dilatation of the arteries of the body generally. It is 
possible, therefore, that this may be the manner in which the effect is 
produced in the liver, and that the glycemia is due to the diminution 
of the amount of oxygenated blood passing to the liver through the 
hepatic artery, causing an excitation of the liver cells, and such conse- 
quent alteration in their metabolic activity as ordinarily accompanies 
excitation.? Many drugs produce temporary diabetes, e.g. acids, such as 
phosphoric, lactic, and hydrochloric, also strychnine, curari, phosphorus, 
arsenic, carbon monoxide. Some of these may act by affecting the 
circulation, others by producing a dyspneeic condition of the liver cells, 
ethers again may be direct stimulants to the hepatic cells.® 


It must be looked upon as a strong argument in favour of the glycogenetic 
theory of Bernard, that we find as a concomitant of the altered (increased ?) 
activity of the hepatic cells, both after removal of the liver from the body, 
and after the diabetic puncture, such an increased production of sugar in the 
organ. It is certainly easier to explain the occurrence of puncture diabetes as 
an excess of the normal production of sugar in the liver, than as a phenomenon 
entirely sai generis. 


Action of the pancreas on carbohydrate metabolism.—Until 
recently, it was not known that the pancreas had any more influence 
upon metabolism than other glands of the same type, such as the 
salivary glands. There had, however, been isolated instances recorded 
in which disease of the pancreas was accompanied by a condition of 
diabetes ; but this, for the most part, was ascribed to the implication of 
the sympathetic ganglia, which are in anatomical relationship to the 
pancreas, and no special importance was attached to the pancreas in 
connection with the symptom.’ It was, however, shown in 1889, by 


1 According to Kaufmann (Compt. rend. Soc. de biol., Paris, 1894, p. 284), puncture 
diabetes is not produced, if the nerves both to the pancreas and liver are cut ; but if one 
set only is severed, it is found to occur. 

2 Even that produced by sections, Kiilz, Arch. f. d. ges. Physiol., Bonn, 1881, Bd. xxiv. 
S. 97. Here also will be found references to previous papers on the subject. 

3 Bernard, ‘* Lecons sur le systeme nerveux,” Paris, 1858, tome ii.; Eckhard, Beitr. 
z. Anat. u. Physiol. (Eckhard), Giesen, Bd. viii. 

4 Filehne, Centradbl. f. d. med. Wissensch. , Berlin, 1878, No. 18. 

(GE Araki, Ztschr. f. physiol. Chem., Strassburg, 1893, Bd. XVil. 

6 References to the literature of some of these substances will be given later ; others will 
be found in Kiilz, loc. cit., supra ; and in Neumeister, ‘‘ Lehrbuch,” Aufl. 2, S. 328. 

7 Since the discovery by v. Mering and Minkowski of the effects of total removal of the 
pancreas, several cases of severe diabetes in man, associated with disease of that gland, 
have been recorded (G. Hoppe-Seyler, Deutsches Arch. f. klin. Med., Leipzig, 1893, Bd. lii, 
S. 171; Buss, Diss., Gottingen, 1895). It must not be supposed, however, that this is at 
all common. In most cases of diabetes no affection of the pancreas can be substantiated. 


928 METABOLISM. 


von Mering and Minkowski, that complete removal of the pancreas in 
the dog, cat, and pig,” is inevitably followed by a very severe form of 
diabetes, having the usual characters of that disease in man, namely, an 
enormous increase in the excretion of water, and the appearance in the 
urine, besides sugar, of aceto-acetic acid, acetone, and sometimes of oxy- 
butyric acid. That this condition is not in any way due to the abolition 
of the secretion of the gland, was further shown by the observation that 
it does not occur if the duct of Wirsung be tied, or if it and its branches 
be blocked by the injection of paraffin into them, and the gland left am 
situ, nor even if a certain proportion of the gland be left, its secretion 
being prevented from passing into the intestine; nor does it occur if a 
portion of the pancreas be detached from its normal position and trans- 
planted elsewhere, either underneath the skin or in the peritoneal cavity, 
and the remainder of the organ subsequently removed, although diabetes 
will appear in the severest form immediately after the removal of the 
transplanted portion from its subcutaneous situation. 

The observations of v. Mering and Minkowski have been repeated 
and extended by Minkowski himself and by many other physiologists. 
The removal of the organ is less difficult than might be supposed, the 
chief precaution to take being to interfere as little as possible with the 
supply of blood to the duodenum. The complete removal is found 
invariably to be immediately followed by a considerable increase of 
sugar in the blood, where the amount of sugar may reach as high as 0°46 
per cent., and its consequent appearance in the urine, in which the 
amount may rise to as much as 8 per cent. or more. In the increased 
amount in the blood pancreatic diabetes agrees with puncture diabetes, 
and differs from phloridzin diabetes, in which, as already stated, the 
amount of sugar in the blood is not increased, although there is a large 
increase of sugar in the urine. Concomitantly with this increase of 
sugar in the blood and its consequent appearance in the urine the 
glycogen of the liver disappears.* When no carbohydrate is given with 
the food, and even during prolonged fasting, the sugar continues to be 
eliminated in considerable quantity; and since, under these circum- 


1 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1889, Bd. xxvi.; see also Minkowski, abid., 
1893, Bd. xxxi. 8. 85. The experiments of v. Mering and Minkowski have been repeated by 
many observers, amongst whom may be mentioned especially Dominicis (Gor. internaz. d. se. 
med., Napoli, 1889), Hédon, Thiroloix, Gley, and Lépine (numerous papers during the last 
seven years in the Compt. rend. Acad. d. sc., Paris; and in the Compt. rend. Soc. de 
biol., Paris; in the Arch. de physiol. norm. et path., Paris; and Arch. de med. exper. 
et @anat. path., Paris); Vaughan Harley, Journ. Anat. and Physiol., London, 1891, vol. 
xxvi. ; Journ. Physiol., Cambridge and London, 1891, vol. xii. p. 391; Caparelli (Adéi d. 
Accad. Gionenia di sc. nat.in Catania, 1892, tome v.; Sandmeyer, Ztschr. f. Biol., Miinchen, 
1893, Bd. xxix. S. 86. 

2 The results in the rabbit were somewhat doubtful, and negative results were obtained 
in birds and in the frog. Aldehoff (Zischr. 7. Biol., Miinchen, 1892, Bd. xxviii.), however, 
has obtained pancreatic glycosuria in the frog; as has also Marcuse (Verhandl. d. physiol. 
Gesellsch. zu Berlin, 1893-94, S. 98, in Arch. f. Physiol., Leipzig), who states that it fails 
to occur if the liver be previously removed. This is also the case, according to Langen- 
dorff (Arch. f. Physiol., Leipzig, 1887, S. 138), with the diabetes produced by strychnine 
and by puncture, but not with that produced by curari. Cf., however, Réhmann, Centra/lbi. 
f. Physiol., Leipzig u. Wien, 1887, Bd. i. S. 122. 

3 Thiroloix (‘‘ Le diabéte pancréatique,” Paris, 1892) at first obtained a contrary result, 
but in later experiments (Arch. de physiol. norm. et path., Paris, Oct. 1892) succeeded in 
confirming the original statement of v. Mering and Minkowski. 

4 According to Hédon (Arch. de physiol. norm. et path., Paris, 1893), the sugar in the 
liver may nevertheless be increased in pancreatic diabetes. The administration of 
levulose causes the reappearance of glycogen in the liver, although dextrose does not 
(Minkowski, Arch. f. exper. Path. u. Pharmakol., Leipzig, 1893, Bd. xxxi.). 


PANCREAS AND CARBOHYDRATE METABOLISM. 929 


stances, its amount, as in the case of phloridzin glycosuria, rises and 
falls with the amount of nitrogen in the urine (see p. 921), it may 
be assumed that it is derived in these cases also from the splitting of 
proteids. 

The exact amount of the pancreas which it is necessary to leave in 
order to prevent the occurrence of glycosuria cannot be exactly given, 
but a comparatively small amount is sufficient. If somewhat less than 
this minimum be removed, diabetes of a less severe type than that 
following complete removal may occur. There is, however, a tendency 
for it to become more severe in process of time, probably from a certain 
amount of atrophy occurring in the pancreatic tissue which has been 
left. 

Cause of pancreatic diabetes.—It appears probable that the pancreas 
exerts its influence upon carbohydrate metabolism, either by promoting 
the formation of glycogen in the liver from the dextrose taken to it by 
the portal blood, or by furthering the oxidation of dextrose in the tissues 
generally. In either case the effect would be the prevention of the 
accumulation of dextrose in the blood, so that the percentage of sugar 
in this fluid would be kept down to its normal, small amount. Whether 
this is brought about by the direct action of the organ upon dextrose 
which reaches it with the blood, or whether it acts indirectly in promot- 
ing the metabolism of dextrose by an internally secreted material, which 
passes out from the organ into the blood and tissues, is a question which 
it is impossible at present to give an answer to. Diabetes which results 
from removal of the pancreas, is not necessarily due to an increased 
elycogenesis from transformation of glycogen (although this is the cause 
of the glycosuria which first makes its appearance), for it will continue 
after the glycogen has completely disappeared from the liver and muscles. 
Moreover, the amount of sugar which is passed is altogether too great 
to be accounted for by the amount of glycogen present in the body. 
Nor is it due to a diminished consumption of sugar by the tissues.” 
It has been suggested that it is caused by the absence of the glyco- 
lytic ferment, which is described as being usually present in the blood. 
Lépine ? has supposed that the pancreas forms sucha glycolytic ferment, 
which effects the splitting of sugar prior to its oxidation in the tissues. 
But Minkowski* has shown that the blood of an animal deprived of its 
pancreas still possesses just as much power of glycolysis as a normal 
animal. Kausch,? who succeeded in producing diabetes in ducks and 
geese by pancreatic extirpation, also found that, after removal of the 
liver in the diabetic animal, moderate amounts of sugar were still con- 
sumed in the tissues. Pancreatic glycosuria diminishes or disappears 
during fever.® 

The symptoms are not allayed by giving raw pancreas with the 
food, as those of thyroidectomy are by feeding with raw thyroid. Nor 


1Cf. Hédon, Compt. rend. Acad. d. sc., Paris, 1893, tome clvi. p. 649; and Thiroloix, 
Arch. de physiol. norm. et path., Paris, 1892. 

* Kaufmann, Compt. rend. Acad. d. sc., Paris, 1894, tome cxviii. p. 656; Arch. de physiol. 
norm. et path., Paris, 1896, p. 151. 

3 “Te ferment glycolytique et la pathogénie du diabéte,” Paris, 1891. Lépine’s theory 
is supported by Vaughan Harley (Brit. Med. Journ., London, 27th August 1892), and 
has been criticised by, amongst others, Spitzer (Berl. klin. Wcehnschr., 1894, S. 949). 

4 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1893, Bd. xxxi. 

> Ibid., 1896, Bd. xxxvii. S. 274; and 1897, Bd. xxxix. S. 219. 

§ Kaufmann, Compt. rend. Soc. de biol., Paris, 1896, p. 227. Fever was found by Poore 
to diminish sugar in natural diabetes (Trans. Clin. Soc. London, 1894). 


VOL. I.—59 


930 METABOLISM. 


are they due to any toxic substance accumulating in the blood (from 
which it might be supposed to be normally removed by the pancreas), 
as has been thought to be the case in the analogous instances of thyroid 
and suprarenal extirpation, for the blood of an animal rendered diabetic 
by pancreatic removal is not found to render a normal animal diabetic. 


The facts clearly show that the diabetes which results from pancreatic 
extirpation is not the result of any interference with the sympathetic nerves 
in the neighbourhood of the organ, nor is it due to the arrest of the passage 
of the secretion of the gland into the intestine, but is exclusively the result 
of the removal of something belonging to the gland which acts in independ- 
ence of its functions in connection with digestion. Since we find in the 
pancreas, if we compare its structure with similar glands such as the salivary, 
that the only important difference is the occurrence in the parenchyma of the 
pancreas of certain cell islands of an epithelium-like appearance richly supplied 
with blood vessels, and entirely unconnected with alveoli or gland ducts, it 
seems reasonable to suppose that the influence, whatever it may be, which the 
pancreas exerts upon carbohydrate metabolism, and which results in the 
excessive formation of sugar on its removal, is due to this particular tissue.? 

That the salivary glands have no such influence upon metabolism as the 
pancreas was shown by Fehr,? and also conclusively by Minkowski,* who, after 
removal in dogs of all the salivary glands, including the orbital glands, found 
no appreciable effects either upon carbohydrate or any other form of metabolism 
to follow the removal. I have myself, in conjunction with Moore, repeated this 
experiment in a dog, removing in successive operations all the salivary glands 
upon both sides, leaving, however, the orbital glands. The animal remained 
in perfect health for several months, and no disturbances could be determined 
in either carbohydrate or proteid metabolism.* 


METABOLISM OF FAT. 


Is the fat of the body directly derived from the fat of the food ? 
—That the fat of the body should be derived from the fat of the food 
seems at first sight extremely probable. But, on consideration, it will 
appear that before it is laid down as the fat of the tissues it would 
probably undergo a change. For the fat of different animals has by 
no means the same composition. Whereas some, such as the dog and 
man, have a large amount of olein in their adipose tissue, and conse- 
quently their fat has a comparatively low melting point, others, such as 
the sheep, have a large proportion of stearin, and the fat of such animals 
has a relatively high melting point. 

Now, if a dog or a man is fed upon sheep’s flesh and fat, the fat 
which is laid up in the body has not a different composition from that 
which it ordinarily possesses. That is to say, a man living upon mutton 
will have his body-fat, not of the consistency of mutton suet, but of the 
ordinary consistency of the fat of the human body, having a melting 
point far lower and containing a much larger amount of olein in its 
composition. 

If, therefore, the fat of the food is laid down as the fat of the body, 
it must undergo important modifications. It is possible to suppose that 
only such portions of the fat of the food as would make fat of the 


1 Schafer, ‘‘On Internal Secretions,” Brit. Med. Jowrn., London, August 1895. 

2 Inaug. Diss., Giessen, 1862 (quoted from Minkowski). 

3 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1893, Bd. xxxi. S. 141. 

4 Proc, Physiol. Soc.,” Journ. Physiol., Cambridge and London, 1896, vol. xix. p. xiii. 


METABOLISM OF FAT. 931 


composition normal to the particular species of animal, are laid down 
directly, and that other portions, such as the excess of stearin which 
occurs in mutton fat, become broken down completely, and either directly 
oxidised, or the products of their decomposition again built up to form 
the normal fat. It has indeed been conclusively proved that the fat of 
the food may be to a certain extent laid down unaltered in the body- 
fat. Dogs which have been starved for a considerable time, so that 
practically the whole of the body-fat has become removed, will, if fed 
upon an excess of mutton fat and sufficient proteid, lay down a body-fat 
of a melting point and composition very similar to mutton-fat. This 
shows that at least a portion of the fat introduced with the food has 
been, for a time at any rate, laid down directly as body-fat.1 

It has been further shown that dogs to which there has been 
administered, along with their food, forms of fat which do not ordinarily 
occur in the animal economy, will lay down a certain amount of this 
along with their body-fat. This has been determined for spermaceti, 
_ linseed oil, and rape oil. That in pigs the fat of the body may also be 
derived from the fat of the food, was shown in some of the experiments 
by Lawes and Gilbert.* 


Formation of fats from fatty acids.—The question of the form 
in which fats are absorbed has been already considered in a previous article 
dealing with that subject, and it has there been shown that the fats of the food 
are in large part not absorbed in the form of fat, but in that of fatty acid, 
into which and glycerin they are broken up by the fat-splitting ferment of 
the pancreatic juice ; and that they undergo a subsequent synthesis into fat 
by combination with glycerin in the columnar epithelial cells of the small 
intestine. 

That such synthesis is possible even in the absence of glycerin given with 
the food, is shown by the experiments of I. Munk, who found that when a 
dog was fed upon fatty acids in place of the fats of its ordinary food, just as 
much fat was absorbed into the chyle and was laid down in the body as if 
it had been fed with the complete fat. The columnar epithelial cells become 
filled with fat globules, as after a meal containing actual fats ; and the synthesis 
of fatty acid and glycerin to form fat must therefore have occurred in these 
cells, which must themselves have produced, in some way which is not under- 
stood, the glycerin necessary for the synthesis.* 


Are fats formed from carbohydrate ?—This is a question of great 
practical importance, seeing that carbohydrate foods are the cheapest forms 
of nutriment, and that the fattening of animals is an important branch of 
agricultural industry. The experience of all rearers of animals for market 
points to the fact that carbohydrates do produce fat. Sheep and oxen 
fed purely upon grass, which contains hardly any fat and but little 
proteid in proportion to the carbohydrate present, lay on a large amount 
of fat, and the artificial foods which are used for fattening purposes 


1 Lebedeff, Centralbl. f. d. med. Wissensch., Berlin, 1882, S. 129; Ztschr. f. physiol. 
Chem., Strassburg, 1882, Bd. vi. S. 149; Arch. f. d. ges. Physiol., Bonn, 1883, Bd. xxxi. 
S. 11; I. Munk, Arch. f. Physiol., Leipzig, 1883, S. 273 (Verhandl. d. physiol. 
Gesellsch. zu Berlin) ; Virchow’s Archiv, 1884, Bd. xev. S. 407. 

2 Radziewski, Virchow’s Archiv, 1868, Bd. xliii. S. 286; Lebedeff, Zoc. cit.; I. Munk, 
loc. cit. See also Minkowski, Arch. f. exper. Path. u. Pharmakol., Leipzig, 1886, Bd. xxi. 
S. 373, and I. Munk and Rosenstein, Virchow’s Archiv, 1891, Bd. exxii. S. 230, for evidence 
that foreign fats pass into the chyle. 

3 See note 2 on next page. 

4For further details regarding these and similar experiments, see article on ‘‘ Fat 
Absorption,” p. 443, 


932 METABOLISM. 


also for the most part contain, in addition to a certain amount of 
proteid, a large proportion of carbohydrate. In spite, however, of this 
almost universal experience, it has been held by C. Voit! that the 
carbohydrates of the food are not directly transformed into the fat of 
the body, but that they only act in promoting the fattening of animals 
by sparing the oxidation of proteid, so that the non-nitrogenous portion 
of the proteid molecule may become transformed into fat. It has been, 
in fact, altogether denied by Voit that the carbohydrates themselves can 
be transformed by the animal economy into fat, in spite of the well- 
established fact that in plants there frequently occurs, especially in the 
ripening of many seeds, a considerable transformation of carbohydrate 
material into fat. The question was, however, brought to the test of 
direct experiment by Lawes and Gilbert.2 These observers took two 
pigs of the same litter, killed one as a control, and determined the total 
amount of fat in its body, and kept another one alive for some weeks, 
feeding it with proteid and an excess of carbohydrate food, and 
determining the exact amount of proteid in such food, then killed it, 
and determined the total amount of fat in its body. They found that 
the amount of fat which had been added on during the time could not 
be accounted for by supposing it to be derived from the proteids of 
the food, since there was not sufficient proteid in the food during the 
period of the experiment to account for more than two-thirds of the 
fat which had been formed, even supposing the whole of its non- 
nitrogenous moiety to have been transformed into fat. Therefore a 
part at least of the fat formed must have been derived from the 
carbohydrate in the food. 


This experiment has since been repeated by subsequent observers on 
different animals, and always with the same result, so that it may be taken 
as conclusively proved that the carbohydrate of the food may be converted 
into fat. The same fact may be shown by balance experiments, in which, 
with nitrogenous equilibrium, there is carbon disappearance in the egesta, 
showing that carbon is stored in the body in quantity more than to be 
accounted for by the carbon of the proteid metabolised ; such laid up carbon 
must be mainly stored as fat. Nor is this formation of fat from carbohy- 
drate by any means a unique phenomenon in the organic world. As we have 
seen, it occurs in plants, in the seeds of which fat is deposited at the expense 
of sugar or starch ; and in the process of fermentation of sugar, acids of the 


1 Hermann’s ‘‘ Handbuch,” 1882, Rd. vi. S. 251 to 260. 

* The very numerous original experiments by these observers, which were begun in 
1847 in the private experimental agricultural station at Rothamstead, are described in 
the following amongst other publications :—Rep. Brit. Ass. Adv. Sc., London, 1852 and 
1854 ; Jowrn. Roy. Agric. Soc. Eng., London, 1849, 1851, 1852, 1853, 1855, and 1860; 
Phil. Trans., London, 1859 ; Scient. Proc. Roy. Dublin Soc., 1864 ; London, Edinburgh, and 
Dublin Phil. Mag., London, 1866 ; Journ. Anat. and Physiol., London, 1877. An excellent 
historical and critical account of the part taken by the various foodstuffs in the metabolic 
processes of the animal economy is given by the same authors in Journ. Roy. Agric. Soc. 
Eng., London, 1895, Ser. 3, vol. vi. pp. 47-141. 

* Soxhlet, Zischr. d. Landw. Vereins in Bayern, 1881; B. Schultze (geese), Landw. 
Jahrb., 1882 ; Tscherwinsky, Landw. Versuchst., Berlin, 1883, Bd. xxix. S. 317. (These 
are quoted from Neumeister, ‘‘ Lehrbuch,” 8S. 368.) See also Chaniewski (geese), 
Ztschr. f. Biol., Miinchen, 1884, Bd. ii. S. 179; C. Voit, Sitzwngsb. d. k.-bayer. Akad. 
d. Wissensch. zu Miinchen, 1885, 8S. 288; Meissl, Strohmer, and vy. Lorenz (pig), Zéschr. 
J. Biol., Miinchen, 1886, Bd. xxii. S. 63; I. Munk (dog), Virchow’s Archiv, 1886, Bd. 
ci. S. 91; Rubner (dog), Ztschr. f. Biol., Miinchen, 1886, Bd. xxii. S. 272. 

4 Meissl and Strohmer, Monatsh. f. Chem., Wien, 1883, Bd. iv. S. 801; Sitzwngsb. d. k. 
Akad. d. Wissensch., Wien, 1883, Bd. lxxxviii.; and Zéschr. f. Biol., Miinchen, 1886, 
loc. cit. ; Rubner, Joc. cit. 


ARE FATS FORMED FROM PROTEIDS OF FOOD? 933 


fatty series are formed. And although it is not easy at first sight to 
understand, from a chemical point of view, how carbohydrate molecules are 
transformed into fatty molecules, we are not obliged to assume direct trans- 
formation, for it may well be that the carbohydrates are broken down into 
comparatively simple compounds, and that these are built up again by the 
organism into fat. 

The observations of Hanriot, with Richet,! furnish indirect evidence of the 
transformation of carbohydrate into fat. These observers found that, with the 
administration of carbohydrate food, there is a greatly increased output of 
carbon dioxide without a corresponding increase of oxygen intake. This fact 
may be explained, according to Hanriot, by a transformation of carbohydrate 
into fat,” in conformity with such an equation as the following :— 


13(C;Hq,0,) = C;;Hy 9405 + 23(CO,) + 26(H,0) 


(oleo-stearo- 
palnitin) 


Are fats formed from the proteids of the food ?—This is a question 
which was for many years held to have been settled by the experiments 
of Pettenkofer and Voit, and subsequently of Voit. These observers 
found that if a dog is kept in a respiration chamber, and fed entirely on 
lean meat, all the ingesta and egesta of the body being carefully deter- 
mined and analysed, a comparison of the results shows clearly that in 
many cases carbon of the proteid is retained within the body, and is 
presumably in the form of fat, the amount of fat and carbohydrate in 
the food being altogether too small to suppose that the carbon laid by 
could have been derived from anything but the proteids of the food. 
Moreover, proteid food increases the amount of fat in the milk of 
suckling animals, and a bitch fed upon lean meat may produce much 
more fat in her milk than can be accounted for by the fat and carbo- 
hydrates of the food—produces, indeed, milk especially rich in fat, when 
fed exclusively on lean meat.* 

In confirmation of observations of this kind have been adduced the 
statements that the milk of suckling animals and of nursing women 
is richer in cream in proportion to the amount of proteid taken in the 
diet ; that fat becomes formed in large amount by the larve of blow- 
flies, which are fed upon defibrinated blood, containing only very small 
quantities of non-proteid organic material;® that in the ripening of 
cheese there is a diminishing amount of proteid, and an increasing 
amount of fat;° and that in the formation of adipocere from flesh, there 
is found a diminished amount of proteids, and an increased amount of 
fatty acids.’ The formation of fat in the liver and tissues of a starving 


1 Compt. rend. Acad. d. sc., Paris, 1892, tome exiv. p. 371. 

2 Cf. also Gautier, ibid., p. 374. 

3 Ann. d. Chem. u. Pharm., 1862, Suppl. Bd. S. 52 and 361; Zéschr. f. Biol., 
Miinchen, 1869, Bd. v. ; also 1870 and 1871, Bde. vi. and vii. ; art. ‘‘ Ernihrung,” in 
Hermann’s ‘‘ Handbuch,” Bd. vi. S. 249. 

4 Ssubotin, Virchow’s Archiv, 1886, Bd. xxxy. 8. 561; and Centralbl. f. d. med. Wiss- 
ensch., Berlin, 1866, S. 337; Kemmerich, zbid., S. 467. Both Ssubotin and Kemmerich 
worked with Ptliiger. See also Voit, Ztschr. f. Biol., Miinchen, 1869, Bd. vy. S. 137. 

> Fr. Hofmaun, Ztschr. f. Biol., Minchen, 1872, Bd. viii. S. 159. 

6 See on the changes accompanying the ripening of cheese, Sieber, Journ. f. prakt. 
Chem., Leipzig, 1880, N. F., Bd. xxi. 8. 203; Jacobsthal, Arch. f. d. ges. Physiol., Bonn, 
1893, Bd. liv. S. 484. 

7 Lehmann (Sitzwngsb. d. phys.-med. Gesellsch. zu Wiirzburg, 1885, S. 19) obtained an 
increase of fatty acids to the extent of 3°7 per cent. in meat kept in running water for some 
months. E. Voit (Miinchen. med. Wehnschr., 1888, S. 518) got an increase of 2 per cent. 
when it was kept in milk of lime, thus excluding fungi. 


934 METABOLISM. 


animal poisoned by phosphorus! also affords strong presumption of the 
conversion of proteid into fat. The fact that in the deposition of fat in 
embryonic adipose tissue the fatty globules are preceded by albuminous 
granules may also be given as evidence in the same direction. 

So important did the extent of such formation of fat from proteid 
appear to Voit, that he endeavoured, as already stated, to account for the 
fattening qualities of carbohydrate food by supposing that it mainly 
acts by sparing the oxidation of the proteids (and fats), thus allowing a 
larger amount of these to be transformed into body-fat.2_ In support of 
his views, he pointed out that if the proteid molecule is supposed to be 
split up, and a portion be removed in combination with the nitrogen 
as urea, the carbon, oxygen, and hydrogen which remain are not very - 
different from the proportion of these elements which would be neces- 
sary for the formation of fat. It was indeed calculated by Henneberg * 
that 51-4 per cent. of proteid taken as food might, under the most 
favourable circumstances, be supposed to be converted into fat. Rubner, 
however, has shown that this estimate is too high. He calculates that 
the utmost amount which could be converted into fat would be about 
46°9 per cent. 

The view that the fat of the body is exclusively derived from the pro- 
teid of the food is, however, no longer held by any physiologists, and Voit 
has himself shown that it must in some circumstances be derived from 
carbohydrate. The above view cannot, indeed, be held, if we accept, as 
we undoubtedly must, the conclusions to be drawn from experiments like 
those of Lawes and Gilbert. These experiments do not by any means 
exclude the formation of fat from proteid, but do exclude the possibility 
of its being formed entirely from proteid, and not from any other article 
of diet. That a certain amount of proteid is necessary to be added to the 
diet of a fattening or suckling animal is a matter of everyday experi- 
ence; but it does not seem to be necessary that this proteid should be 
greatly in excess of that which is necessary to make up for the proteid 
lost from the tissues, or, in the case of the suckling animal, for that also 
which appears as caseinogen in the milk. If, however, the amount of 
proteid in the food is too much decreased, there is more call upon the 
carbohydrates and fats of the food for the immediate production of 
energy, andas a result there will be less of these to be transformed into fat. 

Storch, abstr. in Deutsches Arch. f. klin. Med., Leipzig, 1867, Bd. ii. S. 264; Bauer, 
Ztschr. f. Biol., Miinchen, 1871, Bd. vii. S. 63; ibid., 1878, Bd. xiv. S. 527; Caseneuve, 
fev. mens. de méd. et chir., Paris, 1880, tome iv. pp. 265 and 444; Stolnikoff, Arch. f. 
Physiol., Leipzig, 1887, Suppl. S. 1. Bauer found in a fasting dog, to which phosphorus had 
been administered, as much as 42 per cent. of fat in the muscles, and 30 in the dry liver 
substance, as against 16°7 in the muscles and 10 per cent. in the liver of control dogs. The 
nitrogen excreted is at the same time greatly increased, this also pointing to increased meta- 
bolism of proteid, while there is at the same time a diminished excretion of carbon dioxide, 
and correspondingly Jess oxygen taken in. A similar formation of fat from proteid in 
phosphorus poisoning has been shown by Leo (Ztschr. f. physiol. Chem., Strassburg, 1885, 
Bd. ix. S. 483) to occur in frogs. On the other hand, Lebedetf (Arch. f. d. ges. Physiol., 
Bonn, 1883, Bd. xxxi. S. 11) found in dogs which had previously been fed with linseed oil, 
that the fat in the liver cells, which was formed after administration of phosphorus, had 
the same characters as that which had been laid on in the adipose tissue ; thus indicating 
a transference of fat to the liver rather than its formation there from proteid. Stolnikow 
found in frogs, after extirpation of the “‘fat-body,” that the liver became enlarged, and fat 


accumulated in it under conditions of both carbohydrate and proteid nutriment, even with- 
out the addition of phosphorus to the diet. 


* For further details of the evidence in favour of this view, see Voit, in Hermann’s 
** Handbuch,” Bd. vi. S. 243-251. 

3 Quoted by Voit, Art. in Hermann’s ‘‘ Handbuch,” S. 250. 

4 Biol. Centralbl., Erlangen, 1886-7, Bd. vi. S. 243. 


ACTION OF LIVER IN METABOLISM OF FATS. 935 


That fat is formed from proteid, although not in the exclusive form in 
which Voit at one time was disposed to assert, has been almost universally 
accepted by physiologists ; but this view has been strenuously attacked of late 
by Pfliiger! who has criticised the conclusions drawn by Voit from his experi- 
ments of feeding dogs upon meat, and has shown that in all probability the meat 
employed contained sufficient fat to account for the fat laid on in the body with- 
out supposing this to have been derived from proteid. In a dog kept by himself 
and fed upon a large quantity of meat containing the least possible fat, no fat 
whatever appeared to be laid on; but what was originally present disappeared, 
so that the dog, although muscular and capable of performing severe work, 
was reduced to a condition of extreme leanness. Pfliiger is therefore disposed 
to deny altogether the formation of fat in the animal body from proteid,? and 
considers that its sources are to be looked for exclusively in the fats and 
carbohydrates of the food.* 

In this it would appear probable that Pfliiger has gone as much to 
the one extreme as Voit originally went to the other. It is unquestionable 
that certain forms of bioplasm are capable of transforming proteid into fat 
(as in the instances cited on p. 933). This is, in fact, admitted by Pfliiger, who, 
however, contends that we have no right to assume that other forms of 
bioplasm, such as that of the cells of the higher animals, possess the same 
power. He is disposed to regard the change as due in all the cases cited to 
the action of bacteria and fungi, such as would undoubtedly be present in 
ripening cheese, in putrefying blood, in putrefying flesh, and the like. But it 
has been shown that in flesh kept in milk of lime, and therefore under con- 
ditions unfavourable to the growth of bacteria, fatty acids are still found to a 
small extent, at the expense of the proteid; and the production of fatty degenera- 
tion in the cells of starved animals, to which phosphorus has been adminis- 
tered, is strong evidence in favour of their possessing such a power of forming 
fat from proteid; these, taken in conjunction with the numerous other instances 
which have been cited, appear to indicate that this power of forming fat 
from proteid is a general property of bioplasm. 

As regards the ultimate fate of fat, there seems to be no doubt that it 
becomes oxidised into carbon dioxide and water, thus producing energy which 
may take the form of either heat or work, and that this oxidation takes place 
mainly in the muscular tissue. 


Action of the liver in connection with the metabolism of fats.— 
Very little is known on this question beyond the fact that, under certain 
circumstances, there is a considerable accumulation of fat in the liver 
cells. This has been held by Pavy* to indicate the correctness of his 
view, that fat may be formed both in the liver and elsewhere by the 
direct transformation of glycogen. But it has not been shown that the 
glycogen and fat have any vicarious relation to one another; indeed, the 
contrary was found to be the case by Langley® and by Noél Paton.® 
Nevertheless, Paton’s experiments show a marked increase in the fatty 


1 Arch. f. d. ges. Physiol., Bonn, 1892, Bd. li. S. 229 ; ibid., 1892, Bd. lii. S. 1 and 239. 
2 Kumagawa and Kaneda, Jfitth. a. d. med. Fac. d. k.-jap. Univ., Tokio, 1894, Bd. iii. 
(abstr. in Centralbl. f. Physiol., Leipzig u. Wien, 1895, S. 721), were also unable to obtain 
evidence of fat formation in dogs fed upon food consisting almost exclusively of proteid. 
® For a reply to Piliger’s criticisms, see E. Voit, Miinchen. med. Wehnschr., 1892, 
. 460, and Ztschr. f. Biol., Miinchen, 1896, Bd. xxxii. S. 139; also Cremer, ibid., 1897, 
. 811. Pfliiger’s answer to these is in Arch. ff. d. ges. Physiol., Bonn, 1897, B. Ixviii. 
.176. See also on this subject, I. Munk, Arch. f. d. ges. Physiol., Bonn, 1894, Bd. lviii. 
. 309 ; also Berl. klin. Wehnschr., 1889, No. 9. 
4 « Physiology of Carbohydrates, =p: 258. 
° Proc. Roy. Soc. London, 1882, vol. xxxiv. p. 20; and 1885, vol. xxxix. p. 234. 
5 Journ. Physiol., Cambridge and London, 1896, vol. xix. p. 167. Langley’s state- 
ments are founded upon microscopical observations (in the frog); Paton’s, upon chemical 
evidence. 


MRNMN 


936 METABOLISM. 


acids of the liver of the rabbit at a period after food when the glycogen 
is diminishing, and he concludes that they may have been formed from 
the glycogen.t Langley? has shown that in frogs there is a gradual 
accumulation of fat in the liver, chiefly in the outer zones of the cells, 
during the winter months, a time during which the glycogen is also 
gradually increasing ; and, further, that both the liver fat and glycogen 
tend to diminish on warming the animals in winter. The glycogen 
becomes rapidly used up in the spring, and this is also the case with 
the fat. Paton found (in pigeons) that the liver fat did not appreciably 
diminish as the result of a four days’ fast. Taken by itself, the presence 
of fat in the hepatic cells merely indicates that these cells may act as a 
temporary storehouse for fat. Whether such fat has been formed by 
them from carbohydrate or proteid, or whether it is directly derived 
from the fat of the food, and is in process of transformation in the 
liver cells into a fat more intimately allied to the fat of the body, are 
points which have not yet been determined, but the latter supposition 
appears the more probable; for excess of fat in the food is certainly 
largely stored in the liver cells* And it has been noticed by Lebedeff,4 
and this observation is confirmed by Paton, that the fats of the liver 
contain less oleic acid, and have a higher melting point, than those of 
the body generally. Moreover, as Hofmann showed,® there is a higher 
proportion of free fatty acids in the liver, pointing, according to Nasse, 
to an active metabolism of fats in that organ.’ Lebedeff® found in 
geese which had been fed for six weeks upon peas, which are rich in 
proteid but contain very little fat, that the liver, although containing 
much lecithin, had no fat; and that the fat of the omentum was also 
only present in small amount. A large amount of proteid in the diet 
of rabbits and kittens was found by Paton not to lead to any accumula- 
tion of fat in the liver.® 


' According to Paton, nearly one-half of the fatty acids of the liver are in combination 
with lecithin, See also Heffter, Arch. f. exper. Path. u. Pharmakol., Leipzig, 1891, Bd. 
xxvill. S. 97 ; and Stolnikow, Arch. f. Physiol., Leipzig, 1887, Suppl. Heft, S. 1. 

2 Loc. cit. 

3 Paton, Joc. cit., p. 202. 

4 Ztschr. f. physiol. Chem., Strassburg, 1882, Bd. vi. S. 189. 

SAUOt. Clits p- wl ade 

6 Beitr. z. Physiol. C. Ludwig z. s. 70, Geburtst., Leipzig, S. 184. 

” Biol. Centralbl., Erlangen, 1886-7, Bd. vi. S. 235. 

8 Loc. cit. ® Loe. \eit.,, p. 21s 


THE INFLUENCE OF THE DUCTLESS GLANDS UPON 
METABOLISM—INTERNAL SECRETIONS.* 


By E. A. ScHAFER. 


Contents :—Introductory, p. 937—The Thyroid Gland, p. 938—The Pituitary Body, 
p. 945—The Suprarenal Capsules, p. 948—The Spleen, p. 959. 


CERTAIN organs of the body have a special influence upon some of the 
metabolic processes of the body. Thus the liver fulfils important 
special functions in connection with the metabolism of carbohydrates 
and proteids, and of those organic compounds which contain iron; 
the pancreas has an obscure but absolutely essential function in con- 
nection with carbohydrate metabolism ; and removal of a large portion 
of the kidneys has been shown by Bradford to produce a large increase 
in the proteid waste of the tissues.2 It is also a matter of common 
knowledge that removal of the ovaries or testicles may produce 
profound modifications in the development of other organs, and in the 
general nutrition of the body. In the case of the pancreas (and perhaps 
in that of the kidney) it is by no means improbable that the gland 
yields to the blood some material which influences the carbohydrate 
(and nitrogenous) metabolism of other tissues. In the case of the 
generative glands this is perhaps less probable: it is on the whole 
more likely that these react upon the rest of the organism through the 
nervous system. Numerous observations have of late been published, 
commencing with those of Brown-Séquard, which have seemed to indicate 
that extracts of or the expressed juices of these glands produce, when 
injected hypodermically, beneficial effects upon the nervous and muscular 
systems, but it is not clear that this property is not shared by other 
organs rich in nuclein. Watery extracts or decoctions of the generative 
glands have very much the same action, if injected into a vein, as have 
extracts of other glands. In addition to the above instances, there are 
certain organs of a glandular structure, but destitute of ducts, which 
yield to the blood substances, which are in some cases at least 
absolutely essential to the due nutrition of the body, so that the results 
of the complete removal of these organs is inevitably fatal. These 
substances are no doubt formed by a process of secretion, but since they 
do not find their way to any free surface by means of a duct, but 


1The substance of this chapter was originally given in the form of an address to the 
British Medical Association, and was published in the British Medical Journal tor August 
10, 1895. For the purposes of this book it has been carefully edited and many additions 
have been made to it ; references to literature have also been appended. 

2 Proc. Roy. Soc. London, 1892. vol. li. These researches of Bradford have already 
been noticed in a previous article (p. 656). See also Meyer, Arch. de physiol. norm. et path., 
Paris, 1894, p. 179. 


938 INFLUENCE OF DUCTLESS GLANDS ON METABOLISM. 


presumably reach the blood by means of the lymphatics or blood vessels 
of the organ, they have been termed “ internal secretions.” } 


THE INTERNAL SECRETION OF THE THYROID GLAND. 


The first internal secretion which may be considered is that of the 
thyroid gland. That the thyroid is a secreting gland no one who 
studies its structure and its mode of development can well doubt; 
except that it is unprovided in the adult state with a duct, it has all 
the features of structure of secreting glands. It is formed of alveoli 
which are lined by epithelial cells; and although these cells have not 
been observed to exhibit changes characteristic of secretory activity 
so marked as those which have been noticed under like circumstances 
in the cells of ordinary glands,? we can observe the secreted material 
within the vesicles of the thyroid in the form of the substance known 
as “colloid.” Various attempts have been made to isolate the active 
principle of the secretion: these are referred to in a previous article.* 
According to Drechsel,* there is probably more than one active substance, 
and the secretion may subserve more than one essential function.® 

The gland is extremely vascular and very richly provided with 
nerves, and both blood vessels and nerves come into very close relation- 
ship with the secreting epithelium. The glandular structure of the 
thyroid is more obvious in young than in old animals, and as age 
advances, as has been shown by Hale White® and others, the organ 
undergoes a gradual process of degeneration, so that in advanced age its 
normal glandular structure can only with difficulty be recognised. 

Effects of ablation and disease.—<As long ago as 1856, Schiff? found 
that extirpation of the thyroid in dogs is invariably followed by a fatal 
result. This observation, important as it now seems, fell for many 
years into oblivion, and it was not until clinical observations had again 
pointed to the importance of the gland that Schiff's experiments were 
remembered. It has indeed long been recognised that extensive 
disease of the thyroid, such as occurs in advanced forms of goitre, 
are accompanied by a swollen appearance of the integument, giving a 
misshapen aspect to the features and to the extremities, and leading to 
an idiotic or semi-idiotic condition, which is known as cretinism. In 
1873, Gull§ described a series of symptoms, and especially a condition 
of the integumental connective tissue, similar to that which is met 
with in cretins, the name “myxedema” being subsequently given to 
it, because it was believed to be an cedematous condition charac- 
terised by the presence of a large amount of mucin. That there is an 
excess of mucin over that in ordinary connective tissue has been shown 


* In one sense all the tissues and organs of the body form internal secretions, for they all 
past into the blood materials which have been formed as products of their meta- 

olism. 

* Hiirthle, Arch. f. d. ges. Physiol., Bonn, 1894, Bd. lvi. S. 1; Anderson, Arch. f. 
Anat. u. Entweklngsgesch., Leipzig, 1894, S. 177; Schmidt, Arch. /. mikr. Anat., Bonn, 
1896, Bd. xlvii. S. 181; Galeotti, ibid., Bd. xlviii. S. 305. 

* Halliburton, ‘‘ Chemistry of the Tissues and Organs,”’ p. 88. 

4 Centralbl. f. Physiol., Leipzig u. Wien, 1895, S. 705. 

° Cf. also Notkin, Virchow’s Archiv, 1896, Suppl. Bd. cxliv. 8. 224; Hutchison, 
Journ. Physiol., Cambridge and London, 1896, vol. xx. p. 474. 

° Lancet, London, 1888, vol. i. p. 521. 

7 “Untersuch. ii. die Zuckerbildung,” Wiirzburg, 1859. 

§ Trans. Clin. Soe. London, October 24, 1878 (in vol. vii., 1874). 


THE THYROID GLAND. 939 


by the analyses of Halliburton ;! but not to the extent believed when 
the term myxcedema was applied to this condition. Nor is the condi- 
tion really one of cedema, but rather of hyperplasia of the connective 
tissue, which becomes altered, assuming a more embryonic character, 
hence its richness in mucin (see note 1, p. 942). The connection of 
myxedema with affections of the thyroid was first recognised by Ord ” 
in 1878—an observation which has since been abundantly confirmed. 
In 1882, J. L. Reverdin® described the symptoms which follow com- 
plete removal of the thyroid body for goitre in man, and recognised 
these symptoms as identical with those of the disease which had been 
described under the name of myxcedema; he accordingly termed 
the collection of symptoms “operative myxcedema.”*+ The results of 
Reverdin were speedily followed by those of Kocher, who described, in 
a large number of cases, similar symptoms as following entire removal 
of the thyroid in man.’ Kocher pointed out that the effects are most 
marked in young subjects, and that they may not occur at all or 
be little manifest as age advances. These observations of Reverdin 
and Kocher led to a renewal of his former experiments by Schiff, who 
in 1884 published the results of sixty thyroidectomies upon dogs, in all 
of which the result was speedily fatal,’ the operation being quickly 
followed by the supervention of symptoms—tremors, spasms, and 
convulsions—which seemed to point to a serious derangement in the 
nutrition of the central nervous system.’ Schiff also discovered the 
fact that the symptoms are prevented by a previous graft of a portion 
of the gland beneath the skin or into the peritoneal cavity. 

Dogs do not show the swollen condition of the connective tissues 
which is a characteristic feature after thyroidectomy in man; this 
appears to be due to the fact that in them a fatal result usually occurs 
too rapidly to allow of the development of the so-called “ myxcedema.” 
They are liable, amongst other symptoms, to a form of conjunctivitis 


1 Trans. Clin. Soc. London, 1888, vol. xxi. Suppl.; Journ. Path. and Bacteriol., Edin. 
and London, 1892. 

2 Med.-Chir. Trans., London, 1878. See also Hadden, Brain, London, 1883, p. 198, 
and S. Mackenzie, Trans. Clin. Soc. London, 1888 (Report of Committee on Myxcedema), for 
an account of the symptoms of myxcedema in the human subject. Fora very full bibliography 
of observations on the thyroid and its connection with myxcedema, see Ord, in Allbutt’s 
“System of Medicine,” 1897, vol. iv. . 

: 3 Rev. méd. de la Suisse Rom., Geneve, 1882, p. 539; 1883, Nos. 4 to 6; 1887, pp. 
275, 328. 

+ Termed also ‘‘ cachexia strumipriva”’ and ‘‘ cachexia thyreopriva.”’ 

5 Arch. f. klin. Chir., Berlin, 1883, Bd. xxix. S. 254. 

6 Rev. méd. dela Suisse Rom., Geneve, Feb. and Aug. 1884, Bd. xviii. S. 25. 

7 Schiff’s dogs lived at longest fourteen days, when both lobes were simultaneously 
removed ; if the removal was effected in two sittings, at a certain interval apart, the advent 
of the characteristic symptoms was delayed or altogether averted. 

8 These experiments of Schiff have been confirmed by many subsequent observers, but the 
literature of the subject is enormous, and only a few papers can here be mentioned— Wagner, 
Wien. med. Bl., 1884, S. 25 and 30; Sanguirico and Canalis, Arch. per le sc. med., Torino, 
1884, tome viii.; Horsley, Proc. Roy. Soc. London, 1884 and 1886, and Brit. Med. Journ., 
London, 1885, vol. i. p. 3; 1892, vol. i. p. 267; also Festschr. Rudolf Virchow, Berlin, 
1891; Fuhr, Arch. f. exper. Path. u. Pharmakol., Leipzig, 1886, Bd. xxi.; 1889, Bd. xxv. ; 
Rogowitsch, Centralbl. f. d. med. Wissensch., Berlin, 1886, 8S. 530, and Arch. de physiol. 
norm. et path., Paris, 1888, p. 419 ; Albertoni and Tizzoni, Centralbl. f. d. med. Wissensch., 
Berlin, 1885, S. 419; Hoffa, Sitzwngsb. d. phys.-med. Gesellsch. zu Wiirzburg, 1887, 
S. 104; Ewald, Berl. klin. Wehnschr., 1887, 1889, and 1895; v. Eiselsberg, ‘‘ Ueber 
Tetanie im Anschluss an Kropfexstirpationen,” Wien. klin. Wehnschr., 1890; Gley, 
Arch. de physiol. norm. et path., Paris, 1892, and subsequent volumes ; Cristiani, ibid., 1893 ; 
Langhans, Virchow’s Archiv, 1892, Bd. exxviii. S. 400 ; Domenicis, Wien. med. Wehnschr., 
1895, S. 1620; G. Rouxeau, Arch. de physiol. norm. et path., Paris, 1897, tome ix. p. 136. 


. 


940 INFLUENCE OF DUCTLESS GLANDS ON METABOLISM. 


with leucocytic infiltration of the cornea Horsley was the first to 
operate upon monkeys. He found that these animals survive the 
removal of the thyroid much longer than do dogs, and that in them, as 
in man, a “myxoedematous” condition gradually supervenes. They 
also pass into a condition which is unmistakably similar to cretinism, 
besides which, as in dogs, they are subject to the supervention of muscular 
tremors. These, however, may be greatly abated, or their onset delayed, 
if the animals are kept ina very warm atmosphere. 

It was further found by Allara? and by Ewald? that no results are 
obtainable by thyroidectomy in birds (although it is fatal to reptiles), 
and most observers found the same to be the case with rodents and 
herbivora generally.* It isa noteworthy fact that in aged dogs thyroid- 
ectomy does not produce the normal symptoms. In man also it is 
found that the supervention of operative myxcedema is less frequent as 
age advances.2 The absence of the result in birds has never yet been 
satisfactorily explained; but various attempts have been made to 
explain the frequent absence of result in herbivora.* It may be, either 
that a portion of the gland has been left behind, or that the animals 
were not kept under observation for a sufficient time (Horsley), or 
that there existed in the particular case in question accessory thyroids 
and parathyroids, separated from the main body and not removed in 
the operation. This is the explanation which is given by Gley of the 
negative results which usually attend thyroidectomy in rabbits. Gley 
states that if in these animals care be taken to remove the accessory 
structures as well, the usual symptoms supervene and are very rapidly 
fatal.’ Moreover, he finds that if in young dogs all the parathyroids 
are removed, while the main body of the thyroid is left intact, the 
symptoms which have been regarded as characteristic of complete 
thyroid removal nevertheless supervene, an observation which, if con- 
firmed, shows that it is these structures which are physiologically the 
more important part of the organ.§ 

The symptoms which follow thyroidectomy are of two classes— 
nervous and metabolic, although we are not able to say that the 
nervous symptoms are not produced by metabolic changes in the tissues 
of the nervous system; nor is it certain that the metabolic changes in 


 Gley and Rothon-Duvigneaud, Arch. de physiol. norm. et path., Paris, 1894, p. 101. 

? Sperimentale, Firenze, 1885, p. 281. 

° Ewald and Rockwell, Arch. f. d. ges. Physiol., Bonn, 1890, Bd. xlvii. S. 160. 
ai Sanguirico and Orecchia (abstract in Centralbl. f. Physiol., Leipzig u. Wien, 1887, 

Aol Te Se GEE 

° Bourneville and Bricon (Arch. de neurol., Paris, 1886) have shown that the liability 
to constitutional symptoms usually ceases at about the thirtieth year. 

° According to Briesacher (Arch. f. Physiol., Leipzig, 1890, 8. 509), the character of the food 
in dogs modifies the effects of thyroidectomy. Dogs fed with milk bear the operation better 
than those fed on flesh, nor do they exhibit, as the latter often do, convulsions after a meal. 

” Compt. rend. Soc. de biol., Paris, 1891, pp. 841, 843. See also Edmunds, ‘‘ Proc. Phys. 
Soc.,” Journ. Physiol., Cambridge and London, 1895, vol. xviii. Hofmeister (Beitr. z. 
klin. Chir., Tiibingen, 1894, Bd. ii. S. 441), and Leonhardt (Virchow’s Archiv, 1897, 
Bd. exlix. S. 341) have also got positive results in rabbits ; and G. R. Murray has succeeded 
in producing symptoms of myxcedema in a rabbit from which he had some time previously 
removed the thyroids (Brit. Med. Journ., London, 1896, vol. i. p. 204). 

*Gley, Compt. rend. Soc. de biol., Paris, 1897, p. 181; Vassale and Generale, Arch. 
ital. de biol., Turin, 1895 and 1896, tome xxv. p. 459; and tome xxvi. p. 61; Edmunds, 
‘Proc. Phys. Soc.,” Journ. Physiol., Cambridge and London, 1896, vol. xx. ; also Trans. 
Path. Soc. London, 1895, 1896, and Journ. Path. and Bacteriol., Edin. and London, 
1896, vol. iii. p. 488. Blumenreich and Jacoby (Berl. klin. Wehnschr., 1896, S. 327) state, 
on the other hand, that the inclusion or exclusion of parathyroids is immaterial to the 
result of thyroidectomy (but cf. Gley, Arch. f. d. ges. Physiol., Bonn, Bd. Ixvi. S. 308). 


THE THYROID GLAND. O41 


the tissues are not consequent on alterations in the nervous system.? 
The most characteristic nervous symptoms are those which have been 
already mentioned—muscular tremors, passing gradually into clonic 
spasms, and finally into convulsive attacks (tetany); there is also apathy 
and unsteadiness of gait, and, with the advance of time, the gradual 
supervention of a cretinic condition, together with a lowering of the 
body temperature and a diminution of cutaneous sensibility. The tremors 
also gradually cease. Monkeys die in from five to seven weeks after the 
operation. The tremors are of central origin; they disappear on section 
of the motor nerve (Schiff), but not on removal of the cortical brain 
area concerned with the movements of the part (Horsley). They also 
disappear when a voluntary effort is made, and on reflex irritation. In 
monkeys there is extensor paralysis of the upper limb, and there may 
occur attacks of functional hemiplegia.2 The attacks are diminished by 
administration of potassium bromide.*? The number of red corpuscles 
per ¢.mm. becomes mark- 
edly diminished, while the 
white corpuscles tend to 
increase in number. ‘The 
salivary glands become 
swollen and enlarged, and 
contain an excess of 
mucin. Changes in the 
composition of the blood 
have also been observed,t 
and in the proportions of 
the blood gases, and de- 
generative changes have 
been described in the 
kidneys. It has been 
shown that the excita- 
bility of the cortex of the 
brain, and even of the 
lower centres, is increased 
in animals which have 
suffered from  thyroid- 
ectomy,? but with the Fic. 84.—Monkey deprived of thyroid.—Hors.ey. 
supervention of the cretinous condition it is diminished. The metabolic 
changes which occur are most obvious in the connective tissues, and 

1 Whitwell (Brit. Med. Journ., London, 1892, vol. i. p. 430) found what he regards as 
pathological changes in the nerve-cells of the Rolandic area in a case of myxcedema. Marked 
changes in the nervous elements have also been described as a feature of the condition 
of cachexia thyreopriva ; Kopp, Virchow’s Archiv, 1892, Bd. exxviii. S. 290; Langhans, 
ibid., S. 318; Capobianco, Internat. Monthly Journ. of Anat. and Physiol., 1894, Bd. xi. 
S. 471 (abstract in Centralbl. f. Physiol., Leipzig u. Wien, 1893, Bd. vii. S. 112); Lorrain 
Smith and Pembrey, ‘Proc. Physiol. Soc.,” Journ. Physiol., Cambridge and London, 
1894, vol. xv.; Quervain, Virchow’s Archiv, 1893, Bd. cxxxiii. S. 481. Vassale and 
Donaggio found degeneration in the pyramidal tract (!) of dogs, after extirpation of the 
parathyroids (Arch. ital. de biol., Turin, 1896, tome xxvii. p. 129). 

2 Horsley, Zoc. cit. 

3 Gley, Compt. rend. Soc. de biol., Paris, 1892, p. 300. 

+ Halliburton, Joc. cit. ; Ducceschi, Centralbl. f. Physiol, Leipzig u. Wien, 1895, p. 
359, and 1896, p. 217 ; also Arch. ital. de biol., Turin, tome xxvi. p. 209. 

> Albertoni and Tizzoni, Joc. cit. (see also p. 948). 

® Rosenblatt, Arch. d. sc. biol., St. Pétersbourg, 1894, p. 53. 


7 Autokratoff (abstract in Brain, London, 1890, vol. xxiii. p. 424). 
8 Horsley, Brit. Med. Journ., London, 1892, vol. i. p. 267. 


942 INFLUENCE OF DUCTLESS GLANDS ON METABOLISM. 


especially in the integument. These tissues become swollen and contain 
a superabundance of mucin;! the integument especially swells and the 
eyelids become puffy, but at the same time the surface becomes dry, 
and there is a tendency to the shedding of hairs and of the superficial 
epithelium. This hyperplastic change is followed, if the animal remains 
alive for a sufficient time, by atrophic changes. The nervous affection 
which primarily results is usually accompanied by shght fever. Later 
on this passes off, and the temperature becomes reduced even to some 
degrees below normal.” 

As Schiff originally showed, these effects of thyroidectomy can be 
temporarily prevented by a graft of thyroid; they may also be caused 
to disappear either by injection of thyroid juice into a vein or under 
the skin,? or even by taking thyroid juice or raw thyroid by the 
mouth. The effects of grafts are to all intents and purposes permanent, 
and it has been found, as in the case of the pancreas, that removal of 
the graft which has maintained the health of the animal after extir- 
pation of its own thyroid, is speedily followed—as with primary removal 
of the organ—by the usual symptoms of thyroidectomy. It appears, 
however, to be somewhat difficult to ensure the graft taking.+ 

Theories of action of thyroid extirpation.—Various theories have 
been advanced to account for the effects of removal of the gland. 
H. Munk® held that the effects of removal are due, not to interference 
with the functions of the gland, but to interference with adjoining 
nervous structures in the neck. But this, as with the similar theory 
propounded to account for the effects of extirpation of the pancreas, 
is absolutely negatived if the results of thyroid grafting are to be 
accepted. Besides this theory, two others, out of the many which have 
been put forward, deserve consideration. Of these the one may be 
called the theory of “autotoxication” and the other that of “internal 
secretion.” The autotoxication theory assumes that there are one or 
more toxic substances constantly tending to accumulate in the blood, 
and which it is the purpose of the thyroid gland to remove and 


1F. Semon (Brit. Med. Jouwrn., London, 1883, vol. ii. p. 1073) has enunciated a theory 
which deserves consideration here, to the effect that removal of the thyroid produces an 
interference with the full chemical development of the constituents of the connective 
tissues, so that these tend to take on an embryonic character; and it is well known that 
excess of mucin is characteristic of embryonic connective tissue. 

2 See on this subject, Horsley, Brit. Med. Journ., London, 1892; Ughetti, Riforma 
med., Roma, 1890, vol. vi. p. 228. 

3 Vassale, Riv. sper. di freniat., Reggio-Emilia, 1890, tome xvi. p. 439 (abstract in 
Centralbl. f. d. med. Wissensch., Berlin, 1891, S. 14); and Arch. ital. de biol., Turin, 1892, 
tome xvii. p. 173; Gley, Compt. rend. Soc. de biol., Paris, 1891, p. 251; G. R. Murray, 
Brit. Med. Journ., London, 1891, vol. ii. p. 796 ; 1892, vol. ii. p. 449; 1893, vol. ii. p. 
677; Schwarz, Sperimentale, Firenze, 1892, vol. xlvi.; Arch. tal. de biol., Turin, tome 
xvii. p. 330; Chopinet, Compt. rend. Soc. de biol., Paris, 1892, p. 602; Brown-Séquard, 
Arch. de physiol. norm. et path., Paris, 1892. ; 

4v. Hiselsberg, Wien. klin. Wehnschr., 1892, S. 81. For a successful case of thyroid 
grafting in the human subject, see Macpherson, Hdin. Med. Journ., May 1892. 

5 Sitzungsb. d. k. Akad. d. Wissensch. zu Berlin, 1887, S. 823, and 1888, p. 1059. 
See on the subject of Munk’s experiments, and also on thyroid grafting, Halstead, Johns 
Hopkins Hosp. Rep., Baltimore, 1896, p. 373. The bulk of this paper deals with the 
hypertrophy of the remaining portion which follows the removal of a part only of the 
thyroid. Ina recent paper (Virchow’s Archiv, 1897, Bd. cl. S. 271) Munk endeavours to 
maintain his position. He denies that either cachexia or myxcedema necessarily follows 
thyroidectomy, but in this he is at variance with nearly all other experimenters and with 
the result of clinical experience. 

6 For older theories regarding the functions of the thyroid, see Horsley, Brit. Med. 
Journ., London, 1892, vol. i. p. 267 et seq. 


EFFECT OF THYROID JUICE. 943 


render innocuous.! According to this, the function of the thyroid 
would be primarily excretory. This view is supposed to be sup- 
ported by the observation, that the urine of animals becomes, after 
removal of the thyroid, more toxic than that of normal animals, and that 
the blood is toxic for other animals, and especially for those which have 
already had the thyroid removed, although this operation may have 
been performed only a short time previously, and before the 
symptoms of thyroidectomy have had time to develop. It is not stated 
what the probable nature of this substance is, or by what tissues it 
may be formed. 

Effect of thyroid juice.—The “internal secretion” theory would 
explain the phenomena of extirpation as due to the absence of a 
secretion which is formed within the thyroid or parathyroids, and 
passes from them into the blood; a secretion which is necessary for 
certain of the metabolic processes of the animal body, and especially 
for those connected with the nutrition of the central nervous system 
and of the connective tissues. That this view of the function of 
the thyroid, which was the one given originally by Schiff, is in the 
main the true one, is shown by the fact that beneficial and not 
toxic effects follow the exhibition of thyroid juice, both in cases of 
thyroidectomy in animals and in myxcedema and other affections in 
man. Moreover, extracts of thyroid gland produce distinct physiological 
effects in the normal subject.* If a decoction of the gland be injected 
into a vein, the blood pressure markedly falls (Fig. 85), although the 
beats of the heart remain at about the same rate and of the same 
strength as before. This lowering of the blood pressure is not, however, 
peculiar to the thyroid, but occurs with extracts of some other 
secreting glands. But it has been shown by G. Oliver,> that the 
exhibition of thyroid juice or other preparations of thyroid seems to 
possess a specific tendency to increase the calibre of the radial artery in 
the human subject. It would seem, therefore, that the juice of the 
thyroid, and extracts which are obtained from the gland, have a distinct 
action upon the vascular system. It has further been noticed that feeding 
with thyroid tends to cause increased metabolism in the body, accom- 
panied by diuresis and diminution of fat, so that it has been proposed as 
a cure for obesity. Thyroidectomy alters the conditions of the gaseous 
exchange,’ and this in all probability by an indirect effect through 
the vasomotor system. Lorrain Smith*® found that in animals which 
have been deprived of the thyroid body, the reaction to changes of 
temperature is abnormally rapid. When normal animals are exposed to 
a cold atmosphere, the production of carbon dioxide becomes increased, 
consistently with the increased oxidation which is necessary to cause 

1 Horsley, Proc. Roy. Soc. London, 1886, vol. xl. p. 6; Brit. Med. Journ., London, 
1892 ; Blumenreich and Jacoby, Arch. f. d. ges. Physiol., Bonn, 1896, Bd. xiv. S. 1. 

* Laulanié, Compt. rend. Soc. de biol., Paris, 1891, p. 307 ; see also Gley, zbid., 1894, 
p- 192; and Masoin, zbid., p. 105. 

> Gley, Arch. de physiol. norm. et path., Paris, 1894, p. 484. 

“ Oliver and Schafer, Journ. Physiol., Cambridge and London, 1895, vol. xviii. p. 277. 

> Croonian Lectures, Lancet, London, 13th June 1896. : 

5 Leichtenstern, Deutsche med. Wehnschr., Leipzig, 1894, No. 50. See on the physio- 
logical action of thyroid extract, Ewald, Joc. cit. ; Donatti, Virchow’s Archiv, 1896, Suppl. 
Bd. exliv. 8. 253; Berkeley, Johns Hopkins Hosp. Bull., Baltimore, July 1897. Berkeley 
examined the nerve centres of animals which had died from prolonged administration of 
thyroid extract, but could find no evidence of any changes in the nerve cells. 


7 Michaelsen, Arch. f. d. ges. Physiol., Bonn, 1889, Bd. xlv. S. 622. 
8 Journ. Physiol., Cambridge and London, 1894, vol. xvi. p. 378. 


944 INFLUENCE OF DUCTLESS GLANDS ON METABOLISM. 


an increased production of heat. This increase of carbonic acid does not 
take place immediately, but only comes on after a certain period of 
time; the temperature of the body being in the meanwhile maintained 
normal by those physical changes which occur in the circulation, and 
which allow the quantity of blood 1 rought to the skin, and the amount 
of heat thereby lost from the general surface of the body, to be varied. 
Now, it is precisely these vasomotor changes which appear to be lack- 
ing after removal of the thyroid; for the production of carbon dioxide 
becomes almost immediately increased by exposing thyroidectomised 
animals to a low temperature. Cardiac palpitations with increased 


Fic. 85.—Effect in the dog upon the blood pressure of the intravenous injection of decoc- 
tion of thyroid. Time in seconds. The line above the time tracing is the abscissa 
of the mercurial manometer. 


pulse frequency, often accompanied by a feeling of giddiness, may 
sometimes be produced by large doses of fresh thyroid ; after a time 
glycosuria and increase of urea appear.’ Boe upon the effect 
of thyroid feeding on metabolism have been made by various observers. 
Richter® found in man no marked effect on nitrogenous metabolism, 
but Bleibtreu and Wendelstadt and also Roos got a distinct increase 
of excreted nitrogen during thyroid feeding. Schondorff obtamed an 
increased excretion of nitrogen during the first eight days (in dog); 
after that, N-balance was maintained, while the body- fat was greatly 
diminished in amount. The sodium chloride and phosphoric acid were 
also somewhat increased. Bettmann* states that thyroid feeding tends 
to produce “alimentary glycosuria” (see p. 881). 

* Geor; ciewsky, Centralbl. f. d. med. Wissensch., Berlin, 1895, Bd. xxvii. 

Eas sua Lancet, London, 1893, vol. ii. p.805; V ermehren, Deutsche med. Wehnsehr. , Leipzig, 


1893, No. ; Dening, Miinchen. med. Wehnschr., 1895, 8. 464 ; Bleibtreu and W endelstadt, 
Deutsche ae Wehnschr., Leipzig, 1895, S. 346 ; "Mediger, Diss., Greifswald, 1895 
(abstract in Centralbl. f. Nervenh. u. Psychiat., Coblenz u. Leipzig, Bd. xviii. S. 289) ; 


Lanz, Deutsche med. Wehnschr., pa 1895, S. 597; Irsal, Vas, and Gara, ibid., 1896, 
3d. xxii. S. 439; Schondorff, Arch. f. d. ges. Physiol., Bonn, 1896, Bd. lxiii. 8S. 423; 
Gluzinski and Lemberger, Centralbl. f. innere Med., Leipzig, Bd. xviii. 8S. 90; Roos, Zéschr. 
f. physiol. Chem., Strassburg, 1895, Bd. xxi. S. 19; a 1896, Bd. xxii. S. 18; Giirber, 
Sitzunaqsb. d. phys. -med. Ge sellsch. zu W tirzburg, 1896, S. 101. 

3 Centralbl. f. innere Med., Leipzig, 1896, S. 65. 

4 Berl. klin. Wehnschr., , 1897, S. 518. 


LHENPITOATARY’ BODY; 945 


That the thyroid gland yields an internal secretion which subserves a 
useful purpose within the body, appears to follow conclusively from these 
data, and the effects which follow thyroidectomy are probably due to 
the loss of that secretion. Whether the gland also possesses the 
function of destroying toxie products of metabolism which would other- 
wise tend to accumulate in the blood, a function which has been 
attributed to it by some authors, is a point the evidence regarding 
which is at present insufficient. 

On account of its extreme vascularity and its direct connection with 
the vessels which supply blood to the head, the thyroid has also been 
regarded as exercising a regulatory function on the blood supply to the 
brain,—short-circuiting by vaso-dilatation the cerebral blood flow, or vice 
versd. This view, which was long previously enunciated by J. Simon,* 
has been of late again brought into prominence by Stahel,? whose 
opinion is supported by that of Waldeyer, both of whom approach 
the subject from the anatomical standpoint. More recently the matter 
has been the subject of physiological experimentation by Cyon,* who 
finds that the nerves passing to the thyroid contain powerful vaso- 
dilatators, and that their stimulation may greatly lower the pressure in 
the carotid. Cyon further states that they are called into action 
very easily on excitation of the cut ends of the vagi, of the depressors, 
or of the cardiac branches of the recurrent laryngeal nerves. After 
removal of the gland, the excitability of these nerves is diminished, but 
it is increased by the administration of thyroid preparations. 

The mode of connection which unquestionably exists between turg- 
escence of the thyroid and the other nervous and vascular symptoms 
which characterise Graves’s disease (exophthalmic goitre), is still quite 
obscure. This affection is not, like ordinary goitre and myxcedema, bene- 
fited by thyroid feeding; but various observers have obtained consider- 
able benefit by administration of the uncooked thymus of young animals.® 


THE Pituitary Bopy. 


The next organ the internal secretion of which we may shortly con- 
sider, is the pituitary body. As is well known, the anterior lobe of 
the pituitary body is a structure which may in general terms be described 
as glandular, and although not in all respects resembling the thyroid, 
there are nevertheless certain points both in connection with its mode 
of development, and in the structure of the fully formed organ, which 
might lead to the supposition that there is something functionally 
common to the two organs. 

Effects of removal and disease.—So far as destruction of the 
pituitary body is concerned, experiments have given interesting results. 
The organ has been removed successfully in a number of cases in cats by 
Marinesco,® and in dogs by Vassale and Sacchi.’ In all instances of 
complete removal death ensued, usually within-a fortmight of the 


1 Phil. Trans., London, 1844, p. 295. 

2 Deutsche med. Wehnschr., Leipzig, 1887, S. 227 (quoted by Waldeyer). 

3 Berl. klin. Wehnschr., 1887, S. 233. 

4 Centralbl. f. Physiol., Leipzig u. Wien, 1897, S. 357. 

5 For the literature of this disease, see Ord and H. Mackenzie, in Allbutt’s ‘System of 
Medicine,” 1897, vol. iv. p. 508. 

5 Compt. rend. Soc. de biol., Paris, 1892, p. 509. 

7 Arch. ital. de biol., Turin, 1895, tome xxii. p. 133. 


VOrat——Oo 


946 IVFLUENCE OF DUCTLESS GLANDS ON METABOLISM. 


operation. The symptoms observed were—(1) Diminution of the body 
temperature; (2) anorexia and lassitude; (3) muscular twitchings 
and tremors, developing later into spasms; (4) dyspnea. Many 
of the symptoms show abatement after injection of pituitary extract.’ 
Vassale and Sacchi conclude that the pituitary must furnish an 
internal secretion which is useful in maintaining the nutrition of 
the nervous and muscular systems. Some of these symptoms, especi- 
ally the muscular twitchings, are similar to those seen on removal of 
the thyroid. It has been stated that after thyroidectomy the pituitary 
body becomes enlarged ; and Rogowitsch? has supposed that the fact that 
in rabbits a thyroidectomy sometimes fails to produce the usual results, 
is due to the pituitary taking on a vicarious action, the pituitary being 
larger in proportion in the rabbit than in most animals.? 

Similar statements have been made with regard to its enlargement in 
some cases of myxcedema, in which the pituitary has been examined. But, 
on the other hand, Schénemann,* who examined the pituitary in a large 
number of cases of goitre, got no distinct evidence of its enlargement in 
that disease, nor of any constant change in it, although, im common with 
other structures, it frequently showed pathological alterations. And 
whereas enlargement and degeneration of the thyroid is accompanied 
by cretinism and myxcedema, there appears to be a connection between 
enlargement and degeneration of the pituitary body and an entirely 
different disease, to which the name “acromegaly” has been given by 
Marie,> the most obvious symptoms of which are hypertrophy of the 
bones of the extremities and of the face, with some hypertrophy of the 
skin and mucous membranes, but without mucinoid degeneration.® 

Effects of extracts.—The theory that the thyroid and pituitary 
may act vicariously, appears to be negatived by the physiological effects 
which are produced by extracts of the last-named gland, and which 
differ altogether from those furnished by the thyroid.’ These differences 
are exemplified in Figs. 85 and 86, which show that, whereas decoction 
of thyroid produces no obvious effect upon the contractions of the 
heart, decoction of the pituitary body causes great augmentation in 
the force of the heart’s beat, without, however, any accompanying 
acceleration of the rate. Further, the effect upon the arteries is 
precisely the reverse of that which is obtained by extract of thyroid, 
for, in place of falling, the blood pressure rapidly rises. That this 
rise is not due simply to augmentation of the heart’s beats, but that it 

1 Brown-Séquard, Compt. rend. Soc. de biol., Paris, 1893, p. 527. 

* Beitr. z. path. Anat. u. z. allg. Path., Jena, 1889, Bd. iv. S. 453. 

5 See also, on the subject of the possible connection between thyroid and pituitary, H. 
Stieda, Beitr. z. path. Anat. u. z. allg. Path., Jena, 1890, Bd. vii. S. 537; Pisenti and 
Viola, Centralbl. f. d. med. Wissensch., Berlin, 1890, S. 25 and 26; Hofmeister, doc. cit., 
1894 ; de Coulon, Virchow’s Archiv, 1896, Bd. exlvii. S. 53 ; and Leonhardt, loc. cit., 1897. 

4 Virchow’s Archiv, 1892, Bd. exxix. S. 310. 

> Brain, London, 1889, vol. xii. p. 59. See also Massalongo, Centralbl. f. Nervenh. wu. 
Psychiat., Coblenz u. Leipzig, 1895, Bd. xviii. S. 281. A. Schitf (Wien. klin. Wehnschr., 
1896, Bd. x. S. 277) obtained a marked increased excretion of phosphoric acid on feeding 
with pituitary tablets, with only a very slight increase of nitrogen. He regards this 
experiment as indicating an influence of the extract upon the metabolism of bone. 

° Enlargement of the pituitary only occurred in three cases of acromegaly out of seven 
described by Souza-Leite (Neurol. Centralbl., Leipzig, 1890, Bd. ix. S. 447), who states 
that, on the other hand, persistence of the thymus appears to be a fairly constant accom- 


paniment of that disease. Dreschfeld (Brit. Med. Journ., London, 1894, vol. i. p. 6) 


looks upon the enlargement of the pituitary body as a symptom rather than the cause of 
acromegaly. 


7 Oliver and Schafer, Journ. Physiol., Cambridge and London, 1895, vol. xviii. p. 277. 


EFFECTS OF EXTRACTS: 947 


is also due to contraction of the arterioles, is sufficiently shown by the 
fact that if salt solution containing pituitary extract be passed through 
the blood vessels of a frog, the entire nervous system of which has been 


ence me Te 
ae ae re 
Pi ox : 


2 
a 
= 
| 
| 
f 
4 
: 
a 
3 
Zz 
S 
° 


A 


ut. 


au 


destroyed, the vessels markedly contract. This experiment conclusively 
shows that the effect upon the arteries is a direct one, and in all pro- 
bability the action upon the heart is also direct. 


948 INFLUENCE OF DUCTLESS GLANDS ON METABOLISM. 


We may assume, then, that the pituitary body furnishes to the 
blood an internal secretion, and that this internal secretion tends to 
increase the contraction of the heart and arteries,and perhaps influences 
the nutrition of some of the tissues, especially bone and the tissues of 
the nervous system.' 


THE SUPRARENAL BODIES. 


Effects of disease and ablation.—The immense importance of these 
glands in nutrition was indicated by Addison,? who, in 1855, pointed out 
that the symptoms of the disease now known by his name, the most 
prominent of which are extreme asthenia, and the appearance of bronze 
patches upon the skin and on some of the mucous membranes, are 
associated with pathological alterations of the suprarenal capsules. 
This observation was tested experimentally by Brown-Séquard,? who 
found (in 1856) that removal of the suprarenal bodies was rapidly and 
unfailingly fatal in all animals (usually within twelve hours). Removal 
of one capsule produces no obvious effect, but when the second is re- 
moved, even after a long interval of time, the usual symptoms caused by 
total ablation at once supervene. The symptoms following the removal 
are practically those of Addison’s disease, although much more acute. 
There is extreme muscular weakness, and great loss of tone of the 
vascular system, with loss of appetite, and other signs of general pro- 
stration. Death appears to result from paralysis of the respiratory 
muscles. But the pigmentation which usually accompanies disease of 
the capsules was not noticed by Brown-Séquard, and he inferred that this 
absence of pigmentation was probably due to the fact that a fatal result 
appears so rapidly after the complete removal of the capsules in animals, 
that time is not afforded for the development of this symptom. This 
conjecture appears to have been confirmed by an experiment of 
Nothnagel,t who found pigmented patches to appear after crushing the 
capsules, and also by F. and 8. Marino-Zucco,> who state that by inocu- 
lating the suprarenals of rabbits with pseudo-tubercle bacillus they 
have succeeded in obtaining, not only the slow development of the 
ordinary symptoms of suprarenal removal, but also an augmentation 
in the pigmentation of the skin and hair. Tizzoni also has obtained 
skin-pigmentation after complete and partial removal of the capsules in 
rabbits, which lived a certain time after the operation. 

It is needless to state that Brown-Séquard’s results, following as 
they did upon Addison’s observations, attracted much attention, and 
numerous investigators set to work to verify them. But many of these® 
failed to confirm the results which were obtained by Brown-Séquard, 
probably by reason of the removal being incomplete, or of the existence 


' The thromboses which Mairet and Bosc (Arch. de physiol. norm. et path., Paris, 1896, 
p. 600) obtained from intravenous injection of glycerin- and water-extracts of pituitary 
into rabbits, were doubtless caused by nucleo-proteids. Subcutaneous injection produced 
slight rise of temperature with lassitude and gastric troubles, but as it does not appear 
that the material used was aseptic, these observations are of little value. 

* **On the Constitutional and Local Effects of Disease of the Suprarenal Capsules,” 
London, 1855. 

* Compt. rend. Acad. d. se., Paris, 1856, pp. 422 and 542; Arch. gén. de méd., Paris, 
1856 ; Journ. de la physiol. de Vhomme, Paris, 1858, tome i. p. 160. 

4 Ztschr. f. klin. Med., Berlin, 1879, Bd. i. S. 77. 

° Riforma med., Roma, 1892, tome i. 

® Philippeaux, Compt. rend. Acad. d. sc., Paris, 1856 ; Gratiolet, ibid.; G. Harley, Brit. 
and For, Med.-Chir. Rev,, London, 1858, vol. xxi. p. 204. 


THE SUPRARENAL BODIES. 949 


of accessory capsules ; and after a few months of controversy the subject 
gradually dropped, and became for a long time almost forgotten. The 
interest in this subject has been, however, recently revived, and the 
experiments of Brown-Séquard have been repeated by various observers 
(Tizzoni,! Abelous and Langlois, and many others). I have myself 
made several experiments of the same kind on various animals 
(monkeys, dogs, cats, and guinea-pigs). All these observations have 
tended to confirm the original statements of Brown-Séquard. They 
show that animals deprived of their suprarenal capsules die rapidly, 
usually in the course of one to three days, with the symptoms above 
noted. The further fact is mentioned by Abelous and Langlois, and 
this is also confirmatory of a statement of Brown-Séquard; that the 
blood 4 of animals dying in consequence of the removal of the supra- 
renal capsules is toxic for other animals which have recently been 
deprived of their capsules, although it causes no toxie results in normal 
animals; whereas the transfusion of normal blood into the veins of 
“decapsuled” animals tends markedly to prolong their survival of the 
operation.® 

The symptoms caused by this blood are said by Abelous and 
Langlois to be those of curari poisoning—paralysis, that is to say, of 
the intramuscular nerves;® and since the most marked phenomena 
resulting from removal of the capsules is extreme muscular weakness, 
it has been concluded by them that after removal of these glands 
a certain toxic product of muscular metabolism accumulates in the 
blood, and that the function of the glands is to remove or destroy 
this toxic principle. 

This is the “autotoxication” theory of the suprarenal capsules, and 
is similar to that which has been applied to the thyroid body. Like 
the other avtotoxication theories, it is chiefly founded upon the fact 
that the blood of animals which are moribund in consequence of the 

1 Arch. ital. de biol., Turin, 1886, tome x. p. 3/2; Beitr. z. path. Anat. wu. 2. allg. 
Path., Jena, 1889, Bd. vi. S. 1. Tizzoni thought that removal of one capsule only 
was fatal ; this conclusion was shown to be erroneous by Stilling (Rev. de méd., Paris, 
1890). Tizzoni found in many of his rabbits alterations in various parts of the central 
nervous system, apparently brought on by hemorrhages into the grey matter. 

2 Compt. rend. Soc. de biol., Paris, 1891, p. 835 ; 1892, p. 388: Langlois, ibid., 1893, p. 
444; also in tome iv. of ‘‘ Travaux du Laboratoire de Ch. Richet,’’ 1897, where will be 
found a full bibliography (234 papers) and historical account of the subject of the physiology 
of these organs. Langlois states that it is sufficient to leave ; of the total weight of the 
capsules in the dog in order to insure the survival of the animal. 

3 Journ. de la physiol. de Vhomme, Paris, 1858, tome i. 

4 Also, according to Gourfein (Compt. rend. Acad. d. sc., Paris, 1897, tome cxxy. p. 188), 
alcoholic extracts of the blood and organs of ‘‘ decapsuled”’ animals. 

5 It is stated by Brown-Séquard that injection of extract of suprarenal under the skin 
of animals the suprarenal capsules of which have been removed, has a partial success in 
prolonging life (Compt. rend. Soc. de biol., Paris, 1892, tome xliv. p. 410). But it is 
doubtful if they can be kept alive for any length of time, either by injection in this way 
or by the taking of suprarenal by the mouth. It appears, however, to be true that some 
cases of Addison’s disease are distinctly benefited by extract of suprarenal capsule, taken 
by the mouth, but whether any such cases have been cured is doubtful. (For reference 
to such cases, see Langlois, ‘‘ Travaux du Laboratoire de Ch. Richet,” 1897, tome iv. p. 93 
et seq.). Abelous (Compt. rend. Soc. de biol., Paris, 1892, Nov. 12) and Gourfein (Rev. méd. 
de la Suisse Rom., Geneve, 1896, p. 113) have succeeded in effecting suprarenal grafts 
in the frog, which prevented the occurrence of the usual symptoms when the animal’s own 
suprarenals were destroyed ; on afterwards removing the graft, the symptoms supervened 

“as usual. Dominicis (Wien. med. Wehnschr., 1897, S. 18), on the other hand, operating 
on rabbits and dogs, invariably found a fatal result to follow removal of the second supra- 
renal, after the first one had been successfully grafted. 

6 This statement is, however, denied by Gourfein (Rev. méd. de la Suisse Rom., Geneve, 
1896, p. 113). 


950 IVMFLUENCE OF DUCTLESS GLANDS ON METABOLISM. 


particular extirpation is toxic, especially for other animals which have 
been submitted to the operation. But it is probable that the blood 
of an animal dying slowly as_ the result of any disease, would be to 
some extent toxic, and the toxic principles would more powerfully affect 
animals whose resisting power had been lessened by a recent severe 
operation. However this: may be, whether the suprarenal capsules do 
or do not destroy a toxic principle which is formed elsewhere, and which 
would otherwise accumulate in the blood, they unquestionably produce 
a material which has entirely different properties from those stated to 
be possessed by the blood of animals deprived of their capsules. This 
material, which is probably the basis of the internal secretion of the 
glands, has most active physiological properties. 

Hypodermic injection of extracts—General effects.—The action 
upon normal animals of extracts of suprarenal was first inves- 
tigated by Pellacani and Foa, both alone and in conjunction. They 
injected subcutaneously extracts of the glands, made with water, and 
observed the symptoms which resulted. They found that animals 
(dogs) were killed by subcutaneous injection of extract of calf suprarenal. 
Their results were criticised by Alexander? who pointed out that 
there was liability to chemical change in their preparations, and were 
not confirmed by other observers, but they are, nevertheless, in the 
main correct. 

In conjunction with G. Oliver, I have myself made a number of 
observations upon the effect of subcutaneous injection of water and 
glycerin extracts of suprarenal. We found that the animals were 
usually unaffected by moderate doses, but with larger doses showed 
quickening and augmentation of the heart- beat, “shallow and fast 
respirations, and fall of temperature. Guinea-pigs, we found, would 
stand a large subcutaneous dose of suprarenal extract without 
showing any symptoms at all, or with only a slight acceleration 
and increase of the force of the pulse. The same appeared to be 
the case with the cat and with the dog, unless a very large dose 
were injected, when the symptoms above enumerated became very 


‘marked. Rabbits, on the other hand, were more susceptible to the 


influence of suprarenal extracts. Ifa large dose were given, the animal 
succumbed within half an hour. If, on the other hand, the dose was 
only moderate in quantity, it did not show any symptoms at all for 
some hours, but then it might suddenly succumb. This primary absence 
of symptoms was also noted by Foi and Pellacani in dogs. They state 
that. in many of the animals which they experimented upon in this way, 
there were no symptoms at all apparent upon the day upon which the 
injection was given, but that the next morning the animal was usually 
found dead. The cause of death, it may be added, is not by any 
means clear. Fo’ and Pellacani have supposed that it may be due to 
paralysis of the respiratory centre, but the slight effect which intra- 
venous injection of suprarenal extract produces upon this centre does 
not lend support to this coujecture. 

In frogs we found the effect of the water extract or decoction injected 
into the dorsal lymph sac was to produce a temporary paralysis, which 


' Arch. per le se. med., Torino, 1879, 1880, tomes iii., iv., and vii. ; Arch. ital. de 
biol., Turin, 1883, p. 56. 

2 "Beitr, z. path. anat. w. 2. allg. Path., Jena, 1892, Ba. xi. 

: ante Physiol., Combines and London, 1895, vol. xviii. p. 285. 


INTRAVENOUS INJECTION OF SUPRARENAL EXTRACT. 951 


showed itself in very slow and languid movements. This may, however, 
be due to the veratrine-like effect which the extract produces upon 
muscular tissue (see below). The subject has been worked at more 
recently in my laboratory by Swale ‘Vincent, who has performed 
a large number of experiments upon various animals, and has not only 
confirmed most of our results, but has added several other facts. 
Vincent commonly obtained fatal results in guinea-pigs with doses of 
6 grms. of fresh gland. In rabbits he found the results to be inconstant. 
The hind-limbs become paralysed before the fore-limbs in all animals 
investigated. Doses insufficient to cause a fatal result produce 1m- 
munity to larger doses which would otherwise be fatal, and this effect may 
last a few weeks. The action is produced by the medulla of the gland 
only ; extracts of a large number of other organs and tissues were tried, 
but none produced any effect when injected hypodermically (Vincent). 
Intravenous injection.—The intravenous injection of suprarenal 
extract produces a powerful physiological action upon the muscular 
system in general, but especially upon the muscular walls of the blood 
vessels, and the muscular wall of the heart. A certain amount of action 
is also manifested 
upon some of the 
nerve centres in 
the bulb, especi- A 


ally the ecardio- 
SS ES 


inhibitory centre, 
DDD ID PDP DLP DD DPD DDDPDLPOMLOOYrowomps WEWOwWwew wf WP” 


and to a_ less 
extent upon the 
respiratory 
centre.” 

Action on 
skeletal muscle.— 
The effect upon 
the skeletal 
muscles is well 
shown in the frog 


Fic. 87,—-Effect of suprarenal extract upon muscle contraction in 


ne 7 . = ; : ‘ 
(Fig. 87), and can the frog. A, Normal muscle curve of gastrocnemius ; B, Curve 
also be seen in taken during suprarenal poisoning, but otherwise under the same 
conditions as A. Time tracing, 100 per sec. ® 


mammals. The 
contraction of the muscle in response to a single excitation of its nerve 


1 Journ. Physiol., Cambridge and London, 1897, vol. xxii. p. 111. 

2 Oliver and Schafer, ‘‘ Proc. Physiol. Soc.,” March 1894 (Journ. Physiol., Cambridge 
and London, vol. xvi.) ; ‘‘ Proc. Physiol. Soc.,’”’ March 1895 (ibid., vol. xvii.). These 
were preliminary communications. The detailed account of the experiments is to be found 
in the Journ. Physiol., Cambridge and London, vol. xviii. pp. 230-276. The chemical 
work in connection with our experiments was carried out by Moore ; his papers on the 
subject will be found referred to by Halliburton, on pp. 90-92. Since the first com- 
munication to the Physiological Society there have appeared a large number of papers 
on the subject, for the most part confirming the results there announced. The follow- 
ing are some of these—Szymonowicz, Anz. d. Akad. d. Wiss. in Krakau, February 
1895; Arch. f. d. ges. Physiol., Bonn, 1896, Bd. lxiv. S. 97; Cybulski, Gaz. /ek., 
Warszawa, and Anz. d. Akad. d. Wiss. in Krakau, 1895, reported in Centralbl. f. Physiol, 
Leipzig u. Wien, 1895, S. 172; Velich, Wien. med. Bl., 1896 ; Biedl, Anz. d. k. k. Ges. d. 
Aerzte, in Wien, 1896, and Arch. f. d. ges. Physiol., Bonn, 1897, Bd. Ixvii. ; Gottlieb, Arch. 
f. exper. Path. u. Pharmakol., Leipzig, 1896, S. 99; Ocaha, Act. d. 1. soc. exp. d. Hist. 
Nat., Madrid, 1897. 

3 Figs. 87, 88, 89, 90, and 91 are taken from the Journ. LPhaysiol., Cambridge and 
London. 1895, vol. xviii. No. 3. 


952 IVFLUENCE OF DUCTLESS GLANDS ON METABOLISM. 


is as ready as in the normal animal; but it is greatly prolonged, so that 
the result is comparable to that produced by a small dose of veratria, 


(Tracing reduced to one-half. ) 


, 
5/ 


Intravenous injection of 0°2 grms. dog suprarenal. 


femoral ; D, abscissa of blood pressure ; E, time, 0 


, artificial respiration ; one vagus only cut. 


A, ventricle ; B, auricle; ©, 


Fie, 88.—Dog of 9 kilos. ; morphine 


| 
a 


which, as is well known, has the effect of enormously increasing the 
contraction resulting from a single stimulation of the muscle or its 


INTRAVENOUS INJECTION OF SUPRARENAL EXTRACT. 953 


nerve. 


remain as excitable through their nerves as before. 


effect en- 
tirely dif- 
ferent from 
tine .6.0- 
ealledauto- 
toxication 
paralysis 
which is 
stated to 
result after 
removal of 
the supra- 
renal cap- 
sules in 
animals 
(but see 
note 6, p. 
949), and 
the materi- 
al which is 
extracted 
by water, 
therefore, 
from the 
suprarenal 
capsules is 
certainly 
not the 
same ma- 
terial that 
is said to 
accumulate 
in the blood 
after the 
removal of 
those or- 
gans. 
Action on 
heart and 
pessels.— 
The action 
upon the 
circulatory 
System 
may be di- 
vided into 
the action 
upon the 
heart and 


the action upon the arterial system. 
according as the vagi are cut or uncut. 


ly 
" 


AREA AIOHO SAS AAAS NAA 


| 


a 


Hate 


i, 
i 
aN 


NINE! 


It is in no way comparable to a curari effect, for the muscles 
It is therefore an 


C, blood pressure (carotid artery) ; 


oiled extract, equivalent to 0°2 grms. 


le ; 


A, ventricle ; B, auric 


tfect of intravenous injection of 


E, time in half-seconds. E 


Dog, 9 kilos.; morphine, artificial respiration ; both vagi cut. 
D 
(Tracing reduced to one-half.) 


D, pressure abscissa and signal ; 


fresh suprarenal. 


89. 


Fia. 


Upon the heart the effect differs, 
When the vagi are uncut 


954 LNFLUENCE OF DUCTLESS GLANDS ON METABOLISM. 


and the heart is therefore still in connection with the cardio- -inhibitory 
centre in the medulla oblongata, the action of suprarenal extract is to 
slow, and even to entirely stop, the contractions of the auricle. Under 
these circumstances the ventricle continues beating with an independent 
slow rhythm (Fig. 88). The result is to cause the pulse to be very 
slow. On the other hand, when the vagi are cut or their cardiac ends 
paralysed by atropine, the effect upon the heart is precisely the reverse 
(Fig. 89). The strength and frequency of the auricular contractions 
are markedly increased, and those of the ventricle are correspond- 
ingly augmented. This naturally has the effect of sending a vastly 
greater amount of blood into the arteries, which by itself would alone 
produce a great rise in the arterial pressure. The direct action upon 


Curt ied 


Ay IM) 1) 


Mi MANE 


Dog. ILS Kilos 
Cord cot 


temoriard 
i} Press re, 


Of o-ainme 
Sty? LeWHE 


Fic. 90.—Effect of suprarenal extract upon heart, limb, spleen, and blood pressure, after 
section of cord and vagi. The forearm in this experiment was at first passively 
“las but its contraction is afterwards manifest. (Reduced to one-half.) 


the arteries is, however, quite as marked as that upon the heart. 
If the blood aaa: be taken in a dog in the usual way, by connect- 
ing a mercurial manometer with the femoral artery, and if a minute 
dose of suprarenal extract be now injected into a vein, it is found that 
even with the vagi uncut, and the heart therefore slowed by the action 
of the extract, the blood pressure rises considerably (Fig. 88). But 
with the vagi cut or paralysed by atropine the rise can only be 
characterised as enormous (Fig. 89). 

The contraction of the arteries is further exemplified by the fact that 
if an organ, such as a limb or the kidney or the spleen, be enclosed within 


INTRAVENOUS INJECTION OF SUPRARENAL EXTRACT. 955 


a plethysmograph or oncometer, the instrument indicates a great 
diminution in volume of the organ, which can only be accounted for by a 
contraction of its arterioles! This contraction is produced by the direct 
action of the drug upon the muscular tissue of the smaller arteries, and 
not indirectly through the vasomotor centre ; for it obtains in the mammal 
equally well with the spinal cord cut or the bulb destroyed (Fig. 90), or 
even in the case of the arm after the brachial plexus has been severed 
(Fig. 91). In the frog it is produced also with the brain and spinal cord 
completely destroyed, when salt solution containing suprarenal extract is 
allowed to flow through the arteries. Under these circumstances the 
flow of fluid, which, without the suprarenal extract, may have been com- 
paratively rapid, becomes almost completely stopped, and this can only 
be due to the direct action of the extractive substance upon the muscular 
tissue of the smaller arteries. 

The enormous rise of blood pressure which is got after the vagi have 
been cut, is shown in the tracings (Figs. 89 and 90): the pressure may rise 
to four or five times its original height. Hardly any other agent will 
produce such an enormous increase of pressure, except direct stimulation 
of the vasomotor centre. It is not the case, however, that the elevation 
of blood pressure, and the contraction of the arteries, is due to the 
stimulation of the vasomotor centre by the drug, as was supposed by 
Cybulski and Szymonowicz, for, as we have seen, the action is essentially 
a peripheral one. As shown by Oliver,” it will occur if the extract be 
directly applied to the vessels of the mesentery, either during life or 
in the “ surviving” condition. 


The effect of intravenous injection upon the blood pressure passes off in the 
course of a few minutes. After a dose, no matter whether small or large, has 
been injected into a vein, and has produced the results which we have 
recorded, the blood vessels slowly resume their ordinary calibre, the augmenta- 
tion and increased frequency of the heart’s beats become gradually lessened, 
and the blood pressure recovers its normal condition. Whilst the pressure is 
raised under the action of suprarenal extract, there is apparently no possibility 
of inhibiting the arterial contraction ; even the strongest stimulation of the 
depressor nerve, which under ordinary circumstances produces through the 
vasomotor centre a marked dilatation of the arterioles, is without result during 
the activity of this extract. The question naturally arises, How is it that the 
effect so soon disappears? In what manner is the active principle eliminated ! 
It is not eliminated by the kidneys, for the effect passes off just as quickly 
even although the renal arteries are clamped. It is not eliminated by the 
suprarenals themselves, for the same fact holds good for the suprarenals. It 
passes off almost equally quickly if the aorta and vena cava are tied in the 
upper part of the abdomen, so that there is no circulation of blood whatever in 
the abdominal organs. It is not oxidised or otherwise destroyed by the blood, 
for it retains its full potency even after it has been twenty-four hours in 
contact with that fluid. The most probable explanation of the disappearance 
of the effect seems to be that the active principle becomes packed away, and 
eventually rendered innocuous in certain organs. That the muscles take most 
part in this storage is probable, from the fact that the physiological effects upon 
the skeletal muscles are manifested for a long time after the effects upon the 
heart and arteries have disappeared. 


1 In man the effect of taking suprarenal extract by the mouth is to produce a general 
diminution in calibre of the arteries as measured by the arteriometer (Oliver, ‘‘Croonian 
Lectures,” Zazcet, London, 1896). 

2 ** Proc. Physiol. Soc.,” Journ, Physiol., Cambridge and London, March 1897. 


956 LNFLUENCE OF DUCTLESS GLANDS ON METABOLISM. 


Source of the active material.—The physiologically active material 
is yielded entirely by the medulla of the capsules; no appreciable amount 


, abscissa of blood 
(Reduced to one-half.) 


; B, plethysmographic tracing ot 
- 
Sal 


ssure in femoral ; 


A, time in 0°5’” 


al respiration. 
arm (plexus uncut); C, blood pre 


curari ; vagi cut; artifici 
Kffect of intravenous injection of extract of 0:2 grms. calf suprarenal. 


eut); D, do. of left fore 


; morphine, 
al plexus 


gnal of injection. 


Sf, 


a? 


Oa PN a, oie ea emeaet 


right forearm (brachi 


Fie. 91.—Dog of 20 kilos. 
pressure and si 


can be obtained from the cortex. This result, which was arrived at by 
Cybulski and by ourselves from an investigation of the mammalian 


SOURCE OF THE ACTIVE MATERIAL OF SUPRARENAL. 957 


organ, has been confirmed in an interesting manner by the observations 
of Swale Vincent upon the glands of fishes. Elasmobranchs possess 
two sets of organs, which appear from their structure to represent the 
suprarenal capsules of other vertebrates; the one of these, the inter-renal 
body of Balfour, lies between the posterior part of the kidneys in the 
middle line; the other, the paired bodies of Balfour, forms a series lying 
on either side, segmentally arranged, on the branches of the dorsal aorta. 
Teleosts possess only one kind of gland representing the suprarenal ; 
this in its structure is similar to the inter-renal of Elasmobranchs. As 
Vincent has shown, the minute structure of the paired bodies of 
Elasmobranchs resembles that of the medulla of the suprarenal of other 
vertebrates, while the inter-renal body is similar to the cortex of the 
ordinary vertebrate suprarenal.2 The physiological test shows this in a 
striking manner, for injection of an extract of the paired bodies of 
Elasmobranchs produces in a marked degree the phenomena which are 
characteristic of the medulla of the mammalian suprarenal, while extracts 
of the inter-renals of Elasmobranchs and of the corresponding organs 
of Teleosts have no such effect.* 

Dose.—One of the most interesting and important facts regarding 
the material which is yielded by the suprarenals, is the minuteness of 
the dose which is necessary to produce the results. As little as ¢-0055 
grms. (5} mgrms.) of dried suprarenal is sufficient to obtain a maximal 
effect upon the heart and arteries in a dog weighing 10 kilos. For each 
kilogramme of body weight, therefore, the necessary quantity to produce 
a maximal effect is 0°00055 grms., or little more than half a mgrm.* 
The active principle is, however, contained only in the medulla of the 
gland, not in the cortex,and the medulla in all probability does not form 
more than one-fourth of the capsule by weight. Of the dried medulla 
certainly not less than nine-tenths is composed of proteid and other 
material which is not dialysable, and which otherwise does not conform 
to the chemical properties which are associated with the active substance 
of the gland. So that, if we take these facts into consideration, we find 
that,in order to produce a maximal effect,a dose of not more than fourteen- 
millionths of a grm. of the active material per kilo. of body-weight 
is all that is necessary. Now it is certainly true to say that one- 
fourteenth of this dose will produce some effect, although not perhaps a 
very large one. We thus arrive at the astounding conclusion, that the 
active principle of the suprarenal capsules, administered in the pro- 
portion of not more than one-millionth part of a grm. per kilo. of body 
weight, which would be equivalent to 3355 grms. (less than ,j35 of a 
grain) for an adult man, is still sufficient to produce distinct physio- 
logical results upon the heart and arteries.° 

1 Anat. Anz., Jena, 1897, S. 47 ; ‘‘ Proc. Physiol. Soc.,” Journ. Physiol., Cambridge and 
London, March 1897, and Proc. Roy. Soc. London, 1897, vol. 1xi. p. 64: and vol. Ixii. p. 176. 

2 These homologies were long since inferred by Leydig from a study of their structure 
(‘‘Fische u. Reptilien,” Berlin, 1853), and later by Balfour from a study of their develop- 
ment (‘‘ Comparative Embryology,” 1881, vol. ii. p. 549). 

3 It is, however, difficult to avoid contamination with the paired bodies in extracting 
the inter-renal. Vincent has also found, in an experiment which is not yet published, that 
an eel will survive, for some weeks at all events, removal of the glands which appear to be 
the only representative of the mammalian suprarenals, but contain no medullary tissue. 

4The proportion of suprarenal capsule to body weight is given by Langlois as from 
sesvy to zrboz in the dog. 

5 The chemical nature of this active principle is still obscure, since, in spite of much work 


on this subject, it has never been isolated. The history of this has been already dealt 
with by Halliburton, along with the chemistry of the suprarenals, on pp. 90-92. 


958 4NFLUENCE OF DUCTLESS GLANDS ON METABOLISM. 


Conclusions.—It may be considered probable that the suprarenal 
capsules are continually secreting into the blood an active material, which, 
although present in that fluid only in minute quantities, may yet be suf- 
ficient to produce very distinct effects upon the metabolic processes of 
muscular tissue, and especially the muscular tissues of the vascular 
system. It has, in fact, been stated by 
Cybulski, and this statement has been 
confirmed by Langlois and by Biedl,! that 
the blood of the suprarenal vein contains 
a sufficient amount of the active prin- 
ciple of suprarenal extract to produce a 
marked rise of blood pressure when intra- 
venously injected. I have, in spite of 
careful experiments, not been able myself 
to confirm this statement. Nor is it 
easy to understand how it can be true, 
A. since such blood is constantly flowing 


Fic. 92.—A. Ergograph tracing of a person suffering from Addison’s disease. 
B, Tracing from the same person after six weeks’ treatment with suprarenal 
extract.—Langlois, A, natural size; B, reduced to one-half. 


into the vena cava in larger quantity than these observers injected. 
But whether we are able to show it experimentally or not, there is 
very little doubt of the fact that the materials formed pass somehow 
or other into the blood; and when we compare the results of supra- 
renal injection with the effects obtained from the removal and from 
disease of these organs, we can come to no other conclusion than 
that we have before us a notable instance of internal secretion; and 
that the effect of such secretion passed into the blood is beneficial 
to the muscular contraction and tone of the cardiac and vascular 
walls, and even of the skeletal muscles, appears very evident from 
the results both of removal of the organs and of injection of their 
extracts.” 


1 Arch. f. d. ges. Physiol., Bonn, 1897, Bd. lxvii. 

* This conclusion, which is the one arrived at by Oliver and myself, is ditlerent from that 
of Abelous and Langlois, which they formulate thus :—‘‘ Les capsules suirénales ont pour 
fonction de neutraliser ou de détruire des substances toxiques élaborées au cours des 
échanges chimiques et spécialement au cours du travail des muscles.” This statement, 
which - may be taken to set forth the auto-intoxication theory (supra, p. 949), was made in 
1891, and therefore before the effects of injection of the extract of the medulla were known. 


INFLUENCE OF THE SPLEEN ON METABOLISM. 959 


In advanced cases of Addison’s disease, with complete degeneration of the 
medulla of the suprarenals, an extract of these organs is devoid of all physio- 
logical activity.! Such patients show, as already stated, extreme muscular 
weakness, and very rapidly become fatigued, and their capability of raising a 
weight, as estimated by Mosso’s ergograph, is extraordinarily small. In one 
such case, which was treated by exhibition of fresh capsules of the calf, the 
amelioration of this condition was found by Langlois to be very manifest. 
The above is well illustrated by the accompanying tracings—Fig. 92, A, in a 
patient with Addison’s disease ; Fig. 92, 6, in the same patient after six weeks’ 
treatment with suprarenal capsules of the calf.* The tracings are not strictly 
comparable, for the second one was taken with half the weight, but on the 
other hand it has been reduced to one-half. 


INFLUENCE OF THE SPLEEN ON METABOLISM. 


The constant occurrence and relatively large size of this organ in 
vertebrates, the very large supply of blood which it receives, and its 
intimate anatomical relationships with the digestive organs, would seem 
to render it probable that it must have important functions to perform 
in connection with the nutrition of the body. 

Effects of removal.—This supposition is not, however, borne out by 
the result of experiment, for it has been abundantly proved that 
the spleen can be completely removed in animals and in man without 
their exhibiting any abnormal symptoms whatever.® 

Whether the functions of the organ can be taken up under these 
circumstances by other organs, such as the lymphatic glands, is a point 
which has not yet been determined. Ina dog from which I had removed 
the spleen several months previously, and which was examined for me 
with regard to this pomt by Swale Vincent, there appeared to be a 
larger number of hemal lymphatic glands than in normal dogs,‘ but it 
would require a long series of observations to establish this point 
conclusively. Certainly such a function as the formation of lymph 
corpuscles may well be carried on by the abundant lymphoid tissue 
which is present in other organs of the body; but the spleen has 
undoubtedly, in addition to this,a certain influence upon the hemoglobin 
of some, at least, of the blood corpuscles which are passing through its 
tissue, for we find hemoglobin in various stages of transformation into 
other kinds of pigments within the cells of the organ, and also find a 
relatively considerable amount of iron in loose organic combination. It 
has therefore been supposed that the cells of the spleen pulp may 
produce disintegration of effete red blood corpuscles, and that their 
pigment may pass to the liver, either as free hemoglobin or as formed 
bile pigment. Neither free hemoglobin® nor bile pigment can, how- 
ever, be detected in the blood of the splenic vein. 

On the other hand, the function of producing new red blood 
corpuscles has been ascribed to the spleen, on the grounds that 

1 Oliver and Schafer, Zoc. cit. 

? For other references and observations on the connection between the suprarenals and 
Addison’s disease, see H. D. Rolleston, Goulstonian Lectures, Brit. Med. Jowrn., London, 
1895, vol. i.; and Langlois, ‘‘ Maladie d’Addison,” ‘‘ Dictionnaire de physiologie de Ch. 
Richet,”’ Paris, 1895. 

3 There is considerable literature on this subject. It has been collected by Pernet, and 
is given by him in the British Medical Journal for November 26, 1896. 


+ For an account of these organs, see Swale Vincent and Harrison, Journ. Anat. and 
Physiol., London, 1897, vol. xxi. p. 182. 


° Schafer, ‘Proc, Physiol. Soc.,” May 1890, in Journ. Physiol., Cambridge and 
London, vol, xi, 


960 INFLUENCE OF DUCTLESS GLANDS ON METABOLISM. 


in some animals, eg. rabbits, after extensive blood-letting, nucleated 
erythroblasts, such as those which are found in bone-marrow, occur 
both in the spleen pulp and in the blood of the splenic vein; and that 
if a spleenless animal is bled, the recovery of the usual percentage of 
red corpuscles is less rapid than in a normal animal. 

Whatever may be the nature of its functions in relation to the blood, 
it is certain that the organ is in no way essential to the normal 
nutrition of the body. It is, on the other hand, not at all improbable 
that the main function of the spleen is to serve a mechanical pur- 
pose, answering as a reservoir at certain periods of digestion for the 
blood which has to pass through the portal system; and the fact that, 
as was first shown by Roy, the spleen normally exhibits regular rhythmie 
contractions and dilatations, seems to point to its exercising an influ- 
ence in assisting the flow of blood through the portal vein, and thus 
through the liver.” 

; Ee 

1 Laudenbach, Arch. de physiol. norm. et path., Paris, 1897, pp. 200, 385, and 

2 The functional connection of the spleen with the vascular system is dealt with in the 
article on ‘‘ Circulation” in the next volume. Extracts and decoctions of spleen appear to 
have no specific effect, either when injected subcutaneously or intravenously. Nor is any- 
thing known as to any specific functions possessed by the thymus body or by the carotid 
and coceygeal glands. Extracts and decoctions of the thymus appear to have no specific 
effect when injected intravenously (Oliver and Schifer, Jowrn. Physiol., Cambridge and 
London, 1895, vol. xviii.) or subcutaneously (Vincent, ibid., 1897, vol. xxii.). It has 
been stated that removal of the thymus in frogs is followed by a fatal result (Abelous and 
Billard, Arch. de physiol. norm. et path., Paris, 1896, p. 898), but the statement requires 
corroboration. 


On 


POD Sve 


VON wa ye 


: 
. a é 
. 2 : 7 
j 
i f 
‘ 
@ 
ih .f 
* 
j 4 So 
> x 
a Pz 
1 ' 
' 
‘ 
7 
« 
a 
‘ 
‘ 
. 
: 
> 
fy 
, 
' 
5 


INDEX OF 


SUBJECTS. 


eee 
PAGE PAGE 
ABRIN, 55 Activity co-efficient, 261, 268 
Absorption of acid albumin, . 437 | Adamkiewicz’s reaction, ; : 47 
3 ;, albumose, 437, 489 | Addison’s disease, j 048, 959 
ne alimentary, channels of, . 432 | Adenine, 60, 65, 66, 67, 88, 93, 596 
se seat of, . 432, 541 | Adenyl, ‘ 67 
5 of alkali albumin, 437 | Adenylic acid, OG 
BH », aromatic decomposition Adipocere, 20, 933 
products, 469 | Adipose tissue, fat of, Paes li 
3 ,, bile salts, . 391, 563 » pigment of, =a) 20 
A by blood vessels, 302, 303, 306, Admaxillary glands, 476, 479 
309, 900 | Adsorption, 275 
BA of carbohydrates, 431, 434 | Aerotonometer, 775 
ri ,, dissolved foodstuffs, 5 “Be Aethalium septicum, 80 
as by epithelial cells, 435, 456, 451, Affinity, mechanical, DES 
449, 454, 457, 486, 488, 659,685 | Air, alveolar, 774 


- of fats, 369, 392, 443, 449, 451, 
459, 462 
3 ,, fatty acids, 450, 454, 457 
-. intestinal, 284, 302, 432, 433, 436, 
442, 557 
43 of isotonic fluids, : . 304 
3 by lacteals, 457, 462, 610 
if of lymph, 302, 306 
Be », oxygen by alimentary 
canal, ; 730 
=: >» peptone, - 4387, 439 
3 5, proteids, 431, 436, 437, 440, 900 
33 by rectum, . 436 
55 relation, 215 
. by renal tubules, 650 
Ap skin; Vie ‘ . 685, 688 
re of soaps, 451, 456, 457 
ne by stomach, 432, 541 
8 of tyrosine, 469 
3) Water, . - 4338 
Acetic acid, 5, 19, 31, 34, 75, 355, 464, 471, 
615, 673 
Acetone, 616, 881, 928 
Acetylene hemoglobin, . 242 
Acetyl-lactic acid, 106 
Achromic point, 322 
-Achroo-dextrin, se (165,395 
Acid-albumin, : 50, 167, 404, 408 
ve », absorption of, 436, 437 
Ws “4 carbohydrate from, 64. 
» vegetable, . bil 
Acids of bile. See Bile acids. 

mm OL body, 0 « ‘ ‘ ‘ ‘ 1 
Acrite, : i : : 5 ‘ 6 
Acrolein, 18, 133 
Acromegaly, : 946 
Acrose, A : : : ; = fe Me 
Acrylic acid, 18, 31, 32 


,, changes in, during respiration, 754, 756 


Alanine, ; 31 
Albino rabbit, 37, 173 
Albrecht’s Glaskérper, 222 
Albumin, : F j : 49 
5 acid. See Acid albumin. 
io alkali, 29, 50, 96, 436 


9 99 


reducing substance from, 64 
3 of aqueous humour, 5 


122 


et ash-free, 25 
a assimilation of, 878 
oA of blood plasma, 161, 163 
x », cells, 81, 82 
a 5, chyle, 183 
ne coagulation temperature of, 43 
: egg. See Lgg albwmin. 
59 formula of, 26 
A of intestinal j juice, 557 
55 ,, kidney, 92 
3 ,, lens, 124 
3 ,, liver, 86 
“ Ay Lary eleky Oe 182 
ue », milk. See Lactalbwmin. 
. molecular weight of, = 26 
4s of muscle, . 96, 97, 98 
ab ,, nervous tissues, 2 = abe’ 
i », peas, osazone from, 64 
2 precipitation of, mechanical, 43 
3 ap 5, by salts, 42 
of rotatory power of, 46 
of sebum, ON: 
ne ,, serum. See Serum albumin. 
5 ,, thyroid, : F oo 
Fe in urine, A : . 4387, 604 
vegetable, 51, 54 
Albuminates, ‘ : . 28, 40, 50 
A vegetable, a dail 
Albuminoid degeneration, 74 


964 


Albuminoids, 


? 


INDEX OF SUBJECTS. 


digestion of, 


1, 2, 69, 114 


PAGE 


429 


Albumino-mucous glands, 478 
Albuminous cells, : 477, 478 
5 glands, 477, 503 
a residue of hemoglobin, 243, 244 
Albuminuria, 604 
alim entary, 437 
Albumoid, : 124 
Albumone, Sy, ee ll 
Albumose, 50, 401, 403, 404, 405 5, 416, 899 
3 absor ption of,” 437, 439 
& in bacterial digestion, : 466 
Pe carbohydrate from, 64 
54 classification of, . 410 

“ from fibrin, 7 BT 
x of gastric juice, 353, 355 

e influence of, on coagulation, 146, 
147, 177, 181 
3 55 epithelium on, 440 
59 of intestinal j juice, 557 
59 molecular weight of, 27 
53 nutritive value of, . 878 
8 primary, 412, 416 
= secondary, . Par ab 
a separation of, 411, 412 
of urine, 604 
Albumosuria, 604 
Alcapton, 607, 630 
Alcaptonuria, 607, 630 
Alcohol, ‘ : : 7 
», action of, on proteids, 41 
55 cerotyl, 20 
- ethyl, 470 
= hexatomie, 4 

», influence of, on body tempera- 

ture, : : 820 
55 nutritive value of, 882 
ortho-nitrobenzyl, : 5 

Aldehyde, aspartic, 38, 3 
5 benzoie, a 4, Od 
Aldepalmitic acid, 133 
Aldoses, 4 
Aleuron grains, 51, 52 
Alimentary albuminuria, 437 


Alkali- albumin, 


glycosuria, 


436, 609, 881, 945 
. 29, 50, 96, 436 


5 absorption of, 437 
x5 carbohydrate from, 64 
ices 51 
Alkaline tide, 579 
Alkaloids, action of, on body tempera- 
ture, 821 
i Pe », milk secretion, 664 
5 sl 5, pancreatic secre- 
tion, 548, 550 
3 ; ,, renal secretion, 648 
A ar ,, Salivary secretion, 512 
45 is ,, Skin secretion, 673,679 
ae animal, ¢ 34, 58, 673 
6 in bacterial products, 59, 465 
Alloxan, ; : F 597 
“ reaction of proteids, 48 
> ring, 597 
Alloxantin, = anDoZ 
Alloxuric bases, 66, Han ‘88, 98, 597 
5 nitrogen, 597 
Aluminium, 78 
Alveolar air, 774 
+ surface of lungs, 754 


PAGE 

Alveoli, mammary, 662, 666 
os pancreatic, . 546 

», salivary, 477, 507 
Amanitine, ¢ | 360 
Amido-acetic acid, 31, 373, 378 
Amido-acids, action of liver on, . 906 
af from bile acids, 5 378 


proteid decomposi- 


9? 99 


tion, 29, 30, 31, 32, 403 

‘7 in digestion, 419, 420, 421, 899 

; nutritive value of > sell 
Amido.- butyric acid, 1 ec) 
Amido-caproie acid, ‘as, 31, 421 
Amido-ethy]sulphurie acid, . 373 
Amidogen, : : : 395 
Amido- “glucose, : : : 3 9 
Amido-isethionic acid, 379 
Amido-isobutylactie acid, 28 
Amido-oxethylsulphonie acid, 379 


Amido-pyrotartaric acid, 32, 421, 426 
Amido-succinamie acid, 425 
Amido-suecinie acid, 29, 32, 421, 425 
Amido-valerianic acid, . ; ‘ 

Amido-valerie acid, . 2 ~ Ol, eeor 


Amidulin, 14, 395 
Amigdulin, ’ § 395 
Amines, f : weed 


Ammonia from decomposition of albumi- 
noids, 71, 72, 
73 


;, cerebro- 
sides, 119 
;, proteids, 28, 
30, 31, 32, 34 


2) > 29 


be] +e) > 


xg in digestion, 29, 76, 427, 472 
+ jj, feces, AAS 4 j . 473 
oe 5, putrefaction, . g 76 
= ;, saliva, ; . 3846 

$5 urine, 76, 585, 905 


Ammonio- -magnesic phosphate, 78, 473, 632 
Ammonium carbamate, 582, 583, 673, 906, 


907 
x carbonate, ly 78, 582 
i chloride, 78, 907 
“a lactate, 905, 906, 909 
“ purpurate, - 992 
es salts in blood, 905, 907, 919 
29 be) 23 body, ~ 78 
urate, : : = 18 
Amphibia, respiration of, : . 703, 723 
a skin secretions of, . 673 


Amphicreatinine, ws : , pe 101 
Ampho-albumose, 
Ampho-peptone, 


Amphoteric reaction, . = ’ 576 : 
Amylodextrin, 14, 395 
Amyloid, animal, 133 
degeneration, ( 74 
ms substance, . } 70, 73 


Amylolytic fer ments. See also Ferments. 393 


Amylopsin, 326, 328, 336, 338, 393 
st action of, on amyloses, 326, 394 

<5 influence of reaction on, . 389 

4 3 temperature on, 339 

Amyloses, action of enzymes on, . 3826 
Anabolism, . : 869, 892 
Aniline, : * : = . 34 
Animal alkaloids, 34, 58, 673 
», amyloid, . : : 5 » 133 


pee idextrans =. ‘ a 3 wi¢ TG 


a 


INDEX OF SUBJECTS. 


PAGE 
Animal gun, 14, 16, 62, 65, 126, 133, 158, 
61 3, 665 

poor heat, : - 785 

»,  proteids, . E ; : Jemidd 

3,  proteid poisons, +» . : . 55 

»»  quinoidine,  . ; ; ae kas 
sinistrin, : ; a kee! 
Annclids, hemoglobin of, 187 
Anthrax toxin, . : er pote! 
Antialbumate, : 402, 404, 406, 408 
Anrtialbumid, 403, 404, 405, 406, 408 
Antialbumose, 405, 407, 418 
Antilytic secretion, : - 522 
Antiparalytic secretion, - 522 
Antipeptone, 103, 405, 416, 418, 420 
: i} molecular weight of, eel 
Antitoxins, . : F ; : - BE 
Antivenin, . é ‘ : - Spit 
Apatite, : 112 
Apneea, condition ‘of blood i in, 765 
Apobiotic change, : E 519 
Aqueous humour, : ; 24, 122, 182 
Arabinose, 2, 3, 16, 612 


Arachic acid, - . 138 
Arctic hare, injection of colloids i My rs eer 
Arginine, : 29, 33 
5! production of urea ‘from, 4. 34 
Argon, respiration of, . 754 
Aromatic decomposition pr oducts, absorp- 
tion of, 469 
On proteids, 46, 


39 9 


467, 468 

d’Arsonval’s calorimeter, 845 
Arterial blood, fibrin from, eee GH 
A gases of, 154, 760 

i hemoglobin of, - 180 

oe jecorin of, 165 

6 sugar of, 150 
Arterin, ‘ 190, 192, 225 
Arthr opoda, skeletins of, : ay pee: 
urea in muscles of, 102 

Ash-free albumin, : ‘ : 3g 2b 
Ash of blood, : : : : Smee 
wie 5, bone, E : He ale 
+> 3) caseinogen, 139 
» >, foodstuffs, : 882 
pass liver: : : ‘ t Be tl 
1) ye tangs) : ‘ 5 ‘ ~ Neue 
ye islymph, .. : 77 
ee ,, milk, 77, 131, 662, 885 
*,, 5, muscle, : 77, 109 
+) 3) Dervous tissues, 77, 116 
+> 5) pancreatic juice, 367, 368 


ao 5, proteids,»»: ; : ‘ 2) gy 
> 9) Saliva, 
my) 5, Serum, s ‘ 
Pes Spleen, .. : : : ahd 
+> 3) Succus entericus, 

sf) 5, tooth, 
», urine, ; : : ‘ shure 

Asparagine, : 
Asparaginic acid. ” See “Aspartic Acid. 
Aspartic acid, : . 425 
f % in digestion, 417, 421, 425 
re ;, proteid decomposition, 28, 
29, 32, 34, 36, 73 
u, aldehyde, 


38, 39 
Asphyxia, blood in, 765 
in limited quantity ofa air, 


743 
Asses’ milk, A : ; ; 13] 


965 
PAGE 
Assimilable proteids, 437 
Assimilation, : . 869 
as of proteids, 38, 889 
Atmidalbumin, : . 403 
Atmidalbumose, 403 
Atropine, action of, on body temperature, 821 
>) x ,, milk secretion, 664 

Bs AC ne pancreatic secre- 
tion, 548 

rp s ,, Salivary secretion, 
512, 514, 518 
5 ;, Skin secretion, 680 
Augmented secretion, . , : 497, 525 
Auriculo- temporal nerve, : - 482 
Aussalzung, é 3 = = Es ee 
Autotoxication, ‘ 942, 949 
Avidity coefficient, 357 
> law of, 357 
Avogadro’s hypothesis, 266 


Axilla, temperature of, 787, 788, 824 


Bacteria, action of, in fermentation, 312, 


313, 334 
- Be: gastric juice on, 364, 
402 


on proteids in 
intestine, = 5 29 


32 33 


intestinal, : ; 470 
Bacterial digestion, absorption of pro- 
ducts of, 469 
ee ns of carbohydrates, 464, 
470 
te) re) 9 fats, 471 
fe rr gastric, 463 
8 be intestinal, 464 
a a8 of lecithin, 471 
ap e proteids, ‘ 465 
3 poisons, proteid, . : ‘BS, 59 
x products, alkaloids of, Oo 


1 7, 12, 356 
~ sear Sed 
226, 227, 246 


Bacterium acidi lactici, 
Balance of nutrition, 
Band of Soret, 


Barfced’s reaction, 3 ‘ 3 BS all 
Barley, proteids of, . : : ty 354 
Basophil corpuscles, : . 152 
Bees, temperature of, . : . 192, 807 
Beeswax, : . : 10120 
Benzamido-acetic acid, P 600 
Benzene, : : ; 34, 72, 605 
Benzoic acid, "34, 90, 600, 673, 892 
;, aldehyde, ; 34 
Benzoylglycine, : : ; . 600 
Benzoylglycocoll, : . 470 
Betaine, : - : Sy 
Bicarbonate of sodium, : i TES 
Bile, - . 369, 901 
;; acids, 372, 465, 474, 562 
cleavage products of, . . 378 


2? 2? 


20 ;, isolation of, ; . 374 
at :> properties of, 375, 376, 377 
i ,, tests for, BY 
:, action of, on fats, 369, 392, 444, 455, 
459, 461 

is a3 ,, foodstuffs, 369 
PE 5 », pancreatic diastase, 369 
‘: a »> pialyn, ‘ . Bod 
;, of animals, a 370, 873, 374 
;, chemical composition of, j oY 
;, Cholesterin of, 370, 371, 391, 564, 569, 
901 


966 


Bile, 


nucleo-proteid of, 
pigments, 371, 382, 473, 563, 569, 629, 


INDEX OF SUBJECTS. 


PAGE 

constituents, formation of, . 5 SEY 
specific, 371 

crystallised, 373 
diastatic ferment of, . . 869, 390 
fats in, 17, 370, 371, 390, 564 
inorganic constituents of, 371, 560 


lecithin of, 370, 371, 391, 564 


371, 561, 569 


901 
i s connection of, with he- 
moglobin, 388, 389, 563 
m4 Pe spectrum of, 383, 386, 387, 388 
* = tests for, 384, 385, 386 
5, precipitation of proteids by, . 392 
»» pressure, : 560 
», resin, Mush 
a salts, 371, 372, 456, 562, 568, 569, 901 
Ro tne action of, on heart- beat, 378 
i 55 functions of, 5 eth 
»> 9) Feabsorption of, 391, 563 
»> 9) Separation of, 3874 
,, secretion, direct influence of nerves 
on, 567 
J Fe factors in, . 564 
5 Ph influence of bile- salts on, 568 
= oy A , chemical sub- 
stances on, 567 
” ” ” ” food on, 565 
ne »> 9, hemoglobin 
ons: =) Dod 
3 ee Pe ;, hepatic cir- 
culation on, 565 
5 <3 »> 9, Movement on, 567 
fs BA 5 », Tespiration on, 567 
Ai 5 3 », splanchnic 
nerves on, 565 
- 55 5 5, Starvationon, 565 
7 a mechanism of, . 559; 569 
Ff ¥ relation of, to other he- 
patic functions, . 69 
», solution of fatty acid in, 454, 456 
5, Spectra of, 3 . 390 
,, tension of gases of, 784 
water of, . ; : ; ay 
Bilianic acid, sil 
Biliary fistula, 370, 460 
Bilic acid, wll 
Bilicyanin, . 385, 386 
Bilifulvin, . 383 
Bilifuscin, 386 
Bilihumin, ~uss7 
Biliphain, 382, 383 
Biliprasin, . 387 
Bilipurpurin, 385 


Bilirubin, 382, 383, 389, 474, 563, 567, 622, 629 


Biliverdin, 5 
Bioplasm, 
Birds, gastric glands of, 


382, 384, 385, 473, 474, 629 
: 868, 872 


533 
hematoporphyrin i in, ; ZO 
hemoglobin of, 187, 198, 199, 201, 

204, 206 
nest, edible, 63 
rennin of, . . 3834 
respiration of, - £06, 709; 753 
tail-gland of, . 2 : - 675 
temperature of, . : se 87, 791 
thyroid of, 940 
uric acid of, 909 


urine of, 78, 590, 602, 637, 653 


PAGE 

Biurates, . ; : 588, 590 
Biuret, : c : » ost 
», reaction, 48, 583 
Blood, . «gael 
55 absorption. of solutions by, 279 

se aclaity Aol . 145 

», action of snake- venom on, ss pene 

,, alkalinity of, J . 144 

, ammonium salts i ins F . 905 

;, amount of, : ‘ i by (AT 
EOL animals, ‘ : : 153 

» im apneea,. : ; : . 765 

,, arterial, gases of, . : s/viG0 

| bilirubinini : ; . 383 

5,  cane-sugarin, . : wit do 

,, carbonic oxide in, 237, 240, 741 


cholesterin of, 155, 156, 157, 159 
coagulation of, . 145, 168, 173 

53 % by colloids, si reey 
» >) nucleo- proteids, 55 


colour of, . 142, 233, 237, 240, 241 


composition of, . - . 158 
corpuscles, 141, 147, 152 
5 action of spleen on, . 959 
¥ amount of, : . 147 
ie composition of, 153 
r number of, «t 1495152 
i permeability of, 271, 277 
r red,. . 155, 188, 959 
. white, 83, 141, 152, 158, 
AiSeln9 
defibrinated, composition of, . 154 
dextrose in, 6, 10, 158, 610, 894, 
914, 916, 917, 920, 928, 
925, 928 
dichroism of, . 233 
effect of respiration on, . 756 
ferments of, . : « ‘160; 929 
gases of, . c 154, 235 
» after muscular activity, 715 
,, condition of, 765, 769, 770 
5, estimation of, } 21-457 
5, tensions of, . 776 
in hibernation, . +1 hO6 
lactic acid in, 106, 159, 894, 905 
laking of, . : - - 142, 145 
nitric oxide in, . . . 238 
of portal vein, 900, 908, 917 
oxidation in, 781, 895 
peptone and albumose in, 439 
pigments in urine, é . 629 
plasma, . - 141, 156 
. amount of; { : i. 2a 
- carbohydrates of, . 157 
55 coagulation of, 146 
7 composition of, op wleie 
Be fats of, . 17, 159 
33 inorganic constituents of, 157 
i lactic acid in, 3 ophlae 
aA lipochrome of, 159 
5, nitrogenous constituents 
OF 4 : 160 
o organic constituents of, 157 
proteids of, oo) 24, GE 
platelets, . : . 141, 156, 180 
pressure, influence of, on lymph- 
flow, 299, 
300 


ha »> urinary 
secretion, 5 - . 644 


INDEX OF SUBJECTS. 967 


PAGE 
Blood, quotient, . : : - -) 1b2 
s, reaction of, : | . 144 


», reducing substances of, ah 152; (925 
s specific ‘wravity ofS Ly ; . 143 
3, spectrum of, 208, 211, 225 


;,  sulpho-cyanatein, . i . 346 
», temperature of, . : : . 826 
»,  uncoagulable, . : FLAS; 78 
5, urea in, 160, 900, 902 
», Venous, gases of, : . 760, 762 
», vessels, absorption of lymph by, 302, 
303, 306 
e, “es 33 ,, proteids by, 309, 
900 
Bone ash, . ; : : Saini bY 
Pr chemistry of, - : é 5 alata 
7, earth, . ‘ : : : ee uial 
Border cells, : ‘ ‘ - 2532554 
Bottcher’s test, : a 
Bowman’s theor y of urinary secretion, 639, 
653, 658 
Boyle’s law, : : sZG 
Brain. See Nervous tissues. 
Breast, : - - . 124, 662, 665 
Bromanil, - : : ‘ : 4s Oe: 
Bromelin, . : SE : : yusT54 
Bromoform, UOKS4. 
Brucin, influence ‘of, on n body tempera- 
ture, 5) erat 
Briicke’s method of estimating proteo- 
lysis, . : 323 
a 73 ia cra proteids, 40 
Brunner’s glands, : 554 
Buccal mucus, . ‘ : : 344, 348 
peep CVE, - - : ; - 482 
Buffalo, milk of, . : : a) ST 32, 
Buffy layer, : . : 146 
Butalanine, . ‘ : "31, 32, 421 
Butter, : : ‘ i 133, 834 
;> pigment of, : 20 


Butyric acid, 34, 133, 355, 470, 471, 615, 672 


Cachexia strumipriva vel thyreopriva, . 939 
Cadaverine, : : 59, 60 
Catfein, action of, on renal secretion, . 648 

a influence of, on body tempera- 
ture, . - = - Sh eVAL 


Caisson disease, . : : : F foo 

Calcium, : 
ae carbonate, . 76 78, 11, 344, 501 
a caseate, . - - 135, 136 
My chloride, ‘ 3 ‘ soe Det 
ss fluoride, Z : Sala’ fo) og) | 
= in liver, . : : : el el 
3 oxalate, . SS FSe Gls: 


Ss phosphate, 76; 78, 111, 113, 136, 153 

157, ‘473, 633, 882 
ie salts in body, . F F SE IMLS 
re) as aS egg-yolk, . . . 886 


ie Boo niles, - ; : . 886 

a ;, influence of, on coagulation, 42, 
134, 146, 147, 169, 175, 177, 179 

ee », nutritive value of, . . 886 

5 », in proteids, . ‘ eni26 

in urine, - - . 634 

s sulphate, : : ; PAINTS 

f, urates™ | , : - = +8 
Calorie, ; t : : : . 834 
Calorimeter, : . ; . 844 


Calorimetric experiments, if : . 846 


2? 


bP) 
Capric acid, . 


Carbolic acid, 
Carboluria, 
Carbon, 


33 


bo] 


PAGE 

Camel, milk of, . ee to 
Cane-sugar, 2, 4, 9, 10, 398, 435, 556, 834, 
835, 837 

Es absorption of, . ‘ > 435 

- assimilation of, . . 880, 881 

se digestion of, E 398 

55 inversion of, 10, 398, 556, 558 

in urine, . 881 

Capacity, vital, . 750, 753 


Capillaries, absorption of lymph by, . 806 
alimentary, absorption by,. 483 
ae of, . : > 296 


133, 470, 673 


Caproic acid, 133, 672 
Caprylic acid, 34, 133 
Caramel, - ; 6, 7, 10 
Carbonate of ammonium, : - 906, 907 
Carbohydrates, : 5 ah oe 
absor ption of, : 431 
bacterial digestion of, 464, 470 
of blood plasma, . one LSS 
carbon of, . : . 873 
classification of, . : 4 
in diet, : . 872, 876 
digestion of, - 9855, 393 


fat formation from, . 9381 
heat value of, . 874, 875 
influence of, on bile 


secretion, . : . 566 
of meat, : t z. 96 
metabolism of, . . 916 
of milk, P 3 . 132 
nitrogen of, . - - 873 
from nucleic acid, 66, 67 
nutritive value of, . 880 
from proteids, . . 64 
of urine, j 607 

606, 607, 630 
607, 630 
2 


of foodstuffs, . . . «. 873 
Carbon-dioxide hemoglobin, : . 242 


Carbonate of ammonium, . 78 
33 ;, calcium, 76, 78, 111s 344, 501 
i sodium, : 76, 78, 145, 157 
Carbonates of body, . - : 79 
5 S5) SCEUM;. we : : Ay ti 
Pppllighivese (Ee : : . 634 
Carbonic acid, - 76, 77 
3 5 ’ absorption of, by hemo- 
globin, : : . 173 
5 of alimentary canal, » #29 
3 ,, blood, : 154 
as in bacterial digestion, 29, 470, 
472 
s excretion during inanition, 8&9 
9 in fermentation, . 7, 319 
Me influence of, on coagula- 
FIONA ; 3 SEL 


of milk, . ; «129, 1380 
in muscle, 110, 840, 895, 911 
,, proteiddecomposition, 25, 
28, 31, 34, 71 
,, respiration. (See also 
Respira- 
tion, Tes- 
piratory 
exchange. ) 
692, 700 
ue “4 estimation of, 695 


968 


PAGE 

Carbonic acid, respiration of, 739, 742 
us ;, of saliva, . 9846, 501, 504 
P. 3) 55 Serum, 157 
- 92> 9) Sweat, 671 
5 oS uurines 634 
ss », tension of, in alveolar air, 774 
K. % ;, blood, 775 
», oxide in blood, 237, 240, 741 
if ;, hematin, BZ 
55 ;, hemochromogen, 240, 241,257 
= », hemoglobin, 239 


photographic 
spectrum of, 240 
preparation of, 239 


3 ‘ : reactions of, 240 

é “a : spectro-photo- 

metric con- 
stants of,. 239 
e 5 5S spectrum of, 239 
A, », methemoglobin, 249 
oS respiration of, 740 
Carboxy acids, aromatic, of urine, 606 
Cardia, nerve-centres of, 538 
Cardiac glands, 532, 536 
Carnic acid, . 100, 103, 420 
Carniferrin, . . 103 
Carnine, ; 100, 102, 596, 598 
Carnivora, bacterial digestion in, . 465 
a elimination of phosphates by, 79 
respiratory exchange of, 709 
Carotid gland, 7 960 
Carp, ichthulin of, 64 
Carrotin, 20 
Cartilage, chemistry of, 113 
se fat in, . 17 
55 hyalogen of, 64 
i mucoid of, 63 
Caseate of lime, : 135, 136 
Casein, 134, sie 138, 665, 834, 835, 878 
Pee On colostrum, 127, 129 
;,  dicalecium, . 136 
,, digestion of, 330, 429 
;, leucine and tyrosine from, 425 
5» pancreatic, ‘ 137 
;, rotatory power of, 46 
;; of sebaceous secretion, 665 
», . soluble, 135 
tr icaleium, ; si 
Caseinogen, 126, 128, 134, 135, 137, 138 
= action of rennin on, 826, 334 
ys crystallisation of, 44 
- digestion of, : . 429 
33 mechanical precipitation of, 43 
Caseoses,  . : , ; : ea) 
Castor-oil bean, : ‘ P », 55 
Cat, hemoglobin of, . ‘ : 3), 193 
>» milk of, ; . 130 
3 salivary glands of, 475 
Catalysis, ¢ Be Sly 
Cell albumin, : : 81, 82 
», globulin, 81, 82, 84, 87, 91, 118, 170 

ty ry coagulation of, : 2 

> 29 a, - 82 
io Obs: 298) ules 82, 156 
Cells, action of, in filtration, = 283 
,, albuminous, 477, 478 
;, basophil, me 52 
,, border, é 532, 534 
4 chemical characters of, ; 5 ate 
33 chief, . ‘ : : . 582, 544 


INDEX OF SUBJECTS. 


PAGE 

Cells, demilune, 478 
», eosinophil, 84 
,, of gastric glands, 531, 532 
»> :» intestinal glands, . 554 
5» », Mammary glands, 662, 665 
», metabolism in, . . 869 
¢) aveous: sree : ir 
Ls osmotic pressure of, - 226 
;, oxidation in, , ns, fol 
3) wOxyphil; .. E : : . 152 
,, of pancreas, ; F 546 
5,5 permeability of, eas 
;, of renal tubules, . 654, 659 


ay salivary glands, 477,479, 485, 524, 526 
Cellular absorption, 435, 436, 449, 451, 454, 


659, 685 

», digestion, : - . 399 
Cellulose, : 4, 14, 16, 834, 835 
a bacterial decomposition of, 470 

3 digestion of, ; : - 470 


< in digestion, 471, 881 
Cephalopods, skeletins of, . - eatyndO 
Cerebrin of cells, . : 82, 83 


5% ;, nervous tissues, . 116, 118, ‘119 
; Spleen, : - 87 

Cerebrosides, . 119, 120 
Cerebro- -spinal fluid, 24, 181, 183 
Cerolein, ‘ - aroer2O 
Cerotic acid, é : 2 3 ainpzo 
Cerotyl alcohol, . é - : aton20 
Cerumen, : Sy 
Cervical ganglion, superior, . 484, 523 
Cetyl alcohol, . : 20, 675 
Cetylid, : : : = 120 
Charcot’s crystals, . - «= wO4 
Charles’s law, : ; ; 661265 
Cheese, : ; , 134, 834, 933 

35.08 alkaloidsan:, 3: é sleysd 

Fae oxide; 421 
Chenocholic acid, EE 
Chenotaurocholic acid, . 373, 377 
Chief cells, 532, 544 
Chinese wax, : ; ; 20 
Chitin, ; ‘ : : P oe by: 
Chitosan, é sido 


Chloral, influence of von body temperature 821 
Chlorazol, x 34 
Chloride of ammonium, 
>> ~~», Calcium, : ad 

re. ae potassium, . 25, 76, 77, 93, 157 
sodium, 25, 76, 77, 93, 113, 154, 
157, 882, 883 


78, 907 


2? 2? 


Chlorides in urine, . 633 
Chlorine, ; ; pear i bate! 
Chloro-cruorin, . 61 
Chloroform, influence of, on body tem- 
perature, . : : . 5 Ry Aal 
Cholagogues, ; ; Ped 
Cholalic acid, 373, 374, 378, 380, 381, 562 
Choleic acid, : 373, 381 
Choleinséure, 372 
Cholephain, . : : 383 
Cholepyrrhin, . - : . . 383 
Cholera, alkaloids in, 59 
,,  toxo-peptone, 58 
Cholesterin, 20, 22 


as of bile, 370, Eyal ‘391, 564, 569, 901 
= i blood, 155, 156, "157, 159 
si 55 cells™ i : F 82, 83, 84 
oi >», chyle; ». ‘ ; » 183 


INDEX OF SUBJECTS. 


: PAGE 
Cholesterin of lens, 123 
f », meconium, . . 474 

m ,», milk, 126, 1 28, 129, 133 

5 ;, muscle, . 103 

a3 », hervous tissues, 116 

* ,, red corpuscles, 156 

Rs »retina, . ‘ ‘ py 2 

7 », sebum, . : o) "674. 675 

ns, », Spleen, . : s a ey 

a >» Synovia, : 184 

+c ssubestis, .. : ; ue -93 

A ,, torpedo organ, set 
Choletelin, . ‘ , ; . 385, 388 
Cholic acid, . . 313 
Choline, ‘i 21, 60, 118, 471 
Cholohematin, 390, 564 
Choloidinie acid, . Be ehy 
Chondrigen, 70, 114 
Chondrin, 71, 114 
sy balls, 114 
Chondroitic acid, . 114 
Chondroitin, : aks 
Chondroitin: sulphuric acid, 64, 85, 114 
Chondro-mucoid, . 63, 116 
Chondrosia reniformis, hyalogen of, . 63 
Chondrosidin, . F ‘ xue63 
Chondrosin, 63, 115 


Chorda saliva, 343, 496, 497, 498, 506, 507,511 
», tympani, 479, 505, 509, 519 


Chordo-lingual nerve, 479 
Choroid coat, 1x! 
Chromatic fibres, nucleins of, : 466 
Chromogens of urine, : 626 
Chromophanes, 20, 122 
Chyle, 


- 181, 183, 900 
3, percentage ‘of fat i mh 5 ily 
», proteid in, . avi p24 


PP) 99 
Chymosin, = - : 134 
Cinchonine, 3 . 3 a ek! 
Circulating pr oteids, . 896 
Citric acid, 126, 128, 130 
Classification of albumoses, 410 


aromatic derivatives of 
proteids, . : BHT 


33 2? 


a ;, carbohydrates, . : 4 
3 ,, chemical constituents 
of body, : 
" ,; compound proteids, . 61 
$: 5, enzymes, 326 
eS », mucoids, . - in63 
“a ;, nucleins, 65, 66 
» ,, nucleo-proteids, . at n6Z 
Ee ;, polysaccharides, . ste vel'4 
ie) 5) sproteids; 46, 49 
sugars, 2 
Cleavage theory of proteid digestion, 405, 
406, 414, 416 


Coagulable lymph, - 164, 168 
proteid of digestion, 420, 441 
Coagulated proteids, . : a0 
Bs vegetable, : =~ il 


Coagulating ferments. (Seealso Fibrin- 
Ferment.) . 326, 334 
5a fs of milk, 326, 334 
i 3 5, pancreatic juice, 553 
i ;, stomach, 326 
Coagulation of aqueous humour, 183 
wd ;, blood, : 145 
5 Sono Dlasia. 146 
i, causes of, . 178 


969 

PAGE 

Coagulation, by colloids, st 146, 174 
LA fractional, . : . 43 

A by heat, . : ed? 

ne influence of albumose on, 146, 
147, 177 


, lime salts on, 42, 
134, 146, 147, 169, 
170, 175, 177, 179 

a ee and lungs 

pss 

$5 igmih cells on, 175 

;, nucleo- proteids 
on, 54, 68, 170,176 

», vascular epi- 


thelium on, 180 

a intravascular, 173, 177 

is Pe by snake venom, 57, 

146, 174 

re, of lymph, j . 182, 285 

3 ,, milk, 134, 138, 326, 334 

a ;, muscle plasma, . 95, 96, 97 

5 ,, peptone plasma, oy We: 

Ri ;, pericardial fluid, 183 

23 ,, proteids by alcohol, Sas baal 

; temperature of, . é sind 

; theories of, 168 
water in, ; 319 

Cobalt reaction of proteids, . : 2, 048 
Cobra, venom of, - é . a pre nite) 
Cobrie acid, 7 256 


Cocain, influence of, on body temper ature, 821 
Coceygeal gland, . - : . 960 
Cod, alkaloid in, . : : ‘ “ir60 


Coefficient of activity, . 261, 268 
* », avidity, . A By / 

e ;, dissociation, 268 

55 ;, distribution, =. -oD4: 

Ff ;, extinction, 209, 214, 216, 
234, 239 

” ,», filtration, : 281 

oA isotonic, 270 


CO-hematin, CO- heemochromogen, CO- 
hemoglobin, CO - methemoglobin. 
See Carbonic oxide hemoglobin. 

Cold, effects of, on body, 814, 821 

Cold-blooded animals, temperature of, 787, 792 


Collagen, 70, ar 112, 114, 121, 429 
Collapse air, 752 
Collidine, F 34, 59 
Colloid substances, 5 43 
5, substance of thyroid, "89, 90, 938 
Colloidal solution, 262 
Colloide, : ; : - eo 
sis amido-benzoique, ‘ - . 386 
op aspartique, . : ; 5 ake 
Colloids, filtration of, . : on» 282 
sr intestinal, absorption of, . 4381 
YP osmotic pressure of, 272, 278, 308 
synthesised, 36, 146, 181 
Colostrum, ‘ ‘ 127, 129 
a corpuscles, . . 662 
Combustion, heat of, 834, 837 
Complemental air, 749, 753 
Compound proteids, 49, 61 
»” digestion of, 428 
Compressed air, respir ation offers tye bok 
Conchiolin, . : 5 : a (A, (35.06 
Concretions, salivary, . 345 
Condensation, chemical, 636 
Conduction in heat regulation, 850 


97° 
PAGE 
Conductivity, molecular, . : eo 
Conger-eel, poison of, . : C Ey DD 
Conglutin, . : - ; : OIL 
Congo-red test, . i . 3865 
Constants, spectro- -photometric, 213, 223, 
234, 239 
Contact action, 870, 897, 898 
Contraction of muscle, chemical changes 
during, : : 
Copper, f é : 2, 61, 78, 87 
», reaction of proteids, ‘ 48 
Coral, . : : 75, 78 
Cornea, : 2 : : : = 2 
Cornea-mucoid, 63, 121 
Cornein, . : ; : eA, (5sai6 
Cornicrystallin, : : : or 05 
Corpus luteum, pigment of, . ; a AY 
Corpuscles, basophil, ; 152 
bs of blood. See Blood e co? pus: 
cles. 
ud colostrum, . : : + 1Gb2 
ie eosinophil, . . : 4 Weed 
a oxyphil, . : . - 152 
salivary, 344, 501, 663 
Cortex, cerebral, influence of, on salivary 
secretion, : : . 484 
Cotton seed, proteids of, : : A) doe 
Cow, milk of, : : : #29 
Cranial nerves to saliv ary glands, 479, 482, 
504, 512 
Crawford’s calorimeter, : i 844 
Crayfish, oe Of, a - : . 330 
Cream, ; ; ML25, ASS 
Creatine, i ; ; : . 100 
35 of blood-plasma, : ‘ 60 
i », kidney, . : : « #92 
a », milk, é E : . 126 
z » muscle,- . : . 100, 904 
* ;, Nervous tissues, . : =~) alli6 
a nutritive value of, . 3 . 880 
ay relation of, to lysatine - 33, 427 
S35 of testis, A : aes 
5 55) bor pedo organ, . ; penta le 
35 »» urine, ‘ é : . 598 
Creatinine, é : : 60, 100, 598 
Le of blood plasma, - 160 
sf estimation of, . : Hni599 
Ae identification of, : on 
is isolation of, : : 311/599 
- mercuric-chloride, ‘ . 599 
a of milk, . ‘ A » 126 
a3 ;, muscle, . ; - 100 
a properties Bee 598 
Ee relation of, to lysatinine, 33, 427 
ae salts of, . : : egOO9 
* of sweat, . : : JT 2 
% tests for, . : DOD 
5 of urine, 571, 572, 598, 638 
5 zine-chloride, . és . 599 
Cresol, A 46, 470, 606, 607 
Crotlain, . ‘ : : é 5 BSE 
Cruorin, purple, . ; ; : - 1229 
Crusocreatinine, : : : 61, 101 
Crustacea, hemocyanin oft: ; aro) 
. hemoglobin of, . ; 5 ley 
Af respiration of ene . 102, 703 
7 shell of, ; : ; seaiy8 
es skeletins of, é F any 4 
Crypts of Lieberkiihn, . : ; . 554 
Crystallin, . é . reo LS | 


INDEX OF SUBJECTS. 


PAGE 
Crystalline lens, . : : 4 . 128 
” », fat in, 17, 13 

5, proteid in, 24, 128 


Crystallisation of CO- -hemoglobin, . 239 


a », hemin, . 252, 253 

fe i. hemoglobin, 193, 194, 208, 

205, 232 

i », imtraglobular, 191 

es B:  NO- -hemoglobin, my e241 

Ae 5» proteids, . 43, 163 

a a - vegetable, 27, 52 
Crystallised bile, . ; : : . 373 
Crystalloids, : : : 43, 53 
Crystals, Teichmann’ 8 : - 252, 253 


Curari, influence of, on a tempera- 


ture, 2 . 821, 841 
Curd, . ‘ : J we Be 
Currents of action, é F J . 682 

re ingoing, 5 5 . 682 


3 outgoing, : 5 3 . 682 

i of rest, . - : 9 . 682 
Cutaneous respiration, . e723 
an of amphibia, yeNf23 
»,mammals, . 725 

Cuttle- fish, skeletins of, : , re7 4 


Cyanaleohols, . : , 139 
Cyanhematin, . . : . “249 
Cyanogen hemoglobin, : : . 242 

Ae methemoglobin, : . 248 
Cyanuric acid, . ° ° : . 681 
Cystein, - - - . £ oid 


Cystin, : : , 
Cystinuria, . ; : - o) 2 59682 
Cytoglobin, . - : 2 J JIGS 
Cytosine, . : : : - 66, 632 


Datton’s law, . . . 266 
Degeneration, amyloid or waxy, . rey 
Dehydrocholalie acid, : : . 3881 
Dehydrolysis, . : - : . 636 
Demilune cells, . ‘ 3 . . - 478 

3 glands, : ? : . 478 
Dentine,  . : - @ L2 


Deposit, lateritious, - . : . 588 
Dermoid cyst, . F : 2 675 


Descemet’s membrane, - 64, 121 
Desoxycholalic acid, . 381 
Deutero-albumose, 410, 412, 413, 414, 
416, 418, 420 
Deutero-elastose, 72, 430 
Deutero-gelatose, 71, 429 
Deutero- -proteose, 45, 46 . 


Devoto’s method of separating proteids, 40 
Dextran, animal, 16 


Dextrin, 4, 13, 14, 16, 105, 393, 395, 396 
BS absorption of, . - ‘ . 434 
eee 5 8, 612 
Dextrose, SOF 8, 9; ‘10, 15, 396, 397, 435, 
834, 835, 837 

a assimilation of, . 880, 881 

Be of blood, 158, 610, 894, 914, 916, 


917, 920, 923, 925, 928 
3 ;, muscle, . 100, 105, 110, 606 


- ,> urine, 608, 881, 894, 920, 
926, 928 

Diabetes, 921, 926, 927, 929 
Diabetic puncture, . 4 : - 919 
Diacetic acid, ; , : . 616, 881 
Diacetin,  . - s | as 


Dialysis of proteid solutions, - « ae 


INDEX OF SUBJECTS. 971 


PAGE 

Diamido-caproic acid, 31, 427 
»,  valerianic acid, . : ~ t33 
Diastase animal ou salivaire, : - 327 
Diastase, malt, . - ; «$98; 394 
34 nature of, F ; C = ae. (OF 
Diastasimetry, 322, 325 


160, 319, 322, 325, 326, 

3388, 341, 369, 390, 393, 

398, 399, 508, 552, 556, 

558, 925, 926, 929 

of blood, 160, 929 
estimation of activity 

of, : . 3822, 325 
influence of, on coagu- 


.Diastatic ferments, 


lation, . 146, 147 

mn vegetable, F 3 51 

Dibromacetic acid, : : : . 284 

Dicalcium casein, ‘ ; : . 136 

Diet, composition of, . . » 1872, 875 

», heat value of, . 4 = (8/4.N875 

5, proteid, : : | 891 

3» Special constituents of, : Be S78 

a. stable/of; -«!)). 3 ; : 5 iif 

Diffusion, . : F 7 262 

= of pr oteoses, - . 45 

er in respiratory exchange, e719 

Digestion of albuminoids,  . 429 
of bacterial, absor ption of pro- 

ducts of, . 469 

- a ew Olt carbohydrates, 464, 470 

53 vont eyentatsaa. 470 

a ¥3 gastric, ; : . 463 

us ;, Intestinal, . . 464 

A: », of proteids, . - 465 

ie of cane-sugar, : : . 398 

i ,, carbohydrates, 355, 393 


cellular, : : : . 399 


si of cellulose, . c - . 470 
oe chemistry of, F b S12 
fe of compound proteids, . - . 428 
Pe inten mileriniet 4 . 443 
i 33 fibrin, e . 404 
ip gastric glands during, . 6 3 
x during hibernation, ‘ . 796 
ne im vitro, : 2 : « o2l 
3 mechanism of, ‘ P 5 etl 


Pe peptic, . Z - 401, 418, 428 
of proteids, 333, 338, 399, 402, 414, 
418, 428, 541 

theories of, 400,405,406, 
414, 416 

vegetable, . a5 


9 29 


29 ” 


a of starch, 393, 396, 556 
» tryptic, 414, 418, 428 
4 5 amido-acids of, 2 A421 
ef - ammonia of, . b 427 
af a chromogen of, = 427 


cleavage theory of,. 405 
ores bases of, . 426 
Digestive enzymes, wm 326, 327 
», extracts, 315, 322, 337, 542, 552, 557 
A ferments, 312. See also Enz ymes. 
sh secretions, composition of, . 3842 
Digitalis, action of, on renal secretion, . 649 


29° 29 


Dihydroxyphenyl- ppg oh acid, . . 606 
Diphtheria toxin, : 3 5 iS 
Dippel’s oil, . - : : : . 34 
Disaccharides, 2 j : 3 a ele) 
Dissimilation, . : : . 869 
Dissociation coefficient, : : . 268 


PAGE 

Dissociation of oxyhzmoglobin, . mY 
tension of, BTiLD 

Distearyl- glycero- phosphoric ‘acid, 22 
“a lecithin, ‘ F J e122, 
Distribution coefficient, ; 4 . 354 
Diuréides, . : : : : . 586 
Diuretics, . 647. 
Dog, hemoglobin of, 193, 198, 199, 201, 202, 
203, 206 

», milk of, : r : ‘ 130, 131 

,, Yespiratory exchange of, - 707 

>» Saliva of, 327, 345, 346, 347, 348 
salivary glands of, 2 - 475 
Dolphin, milk of, : : : — Lol 
Drechsel’s bases, 38, 34, 426 


Duboisine, action of, on sweat secretion, 680 
Dulcite, : : 

Dulong’ s calorimeter, : ‘ : . 844 
Dysalbumose, ; : 5 : . 410 


Dyslysins, 378, 380, 382 
Dyspeptone, < 403, 429 
Dyspneeic secretion of saliva, 493, 521, 522 
Ecxr’s fistula, : : : : . 908 
Edestin, z : ‘ F - 54 


: . 25, 26, 27 
action of for maldehyde on, 50 
Pe crystallisation of, . AS 
Gs leucine and tyrosine from, 425 


Egg albumin, 


3? 


a mechanical pearson 

of, : 43 
a reducing substance from, 64 
ng rotatory power of, . 46 


temperature of coa gulation 
of, . : : ato 


shell; .. : : : co 
ap white, composition Dine - . 874 
5 digestibility of, : - . 333 

Ai heat value of, . é - 834 

A mucoid of, . - 5 + 463 

», yolk, composition of, . : . 874 
- fat of, . ‘ : : ah ra’ 

a hematogen of, , : . 68 

a heat value of, : : . 834 

- pigment of, . ; : =fH20 
lime in, é ; . 886 

Ehrlich’s test for bilirubin, : : . 384 
Eiweisskorper,  . : a £49 
Elasmobranchs, muscles of, . 904, 908 
suprarenals of, é 957 

Elastin, : LOM aS; 111, 112 
», decomposition of, . 32 

;, derivatives of, . : - nil 

», digestion of, . : 3 . 430 
peptone, . 72, 430 


Electrical changes in salivar y glands, SLs 
,, skin glands, . 68 


9 23 
3 currents. (See Currents.) . 682 
organs, . : . eS AU 
Electrolytes, diffusion of, . 261, 263 
% osmotic pressure of, . . 268 
pene nee of, t . 276 
Electro- osmose, . : . 688 
Eleidin granules, : ; ; ‘ eh (C) 
Elementary particles, . 2 : . 141 
Elephant, milk of, ; : : Wrst 
Embryo, respiration of, : : - 733 
Emulsification, . , F F 19, 444 
; in intestine,. 447, 457, 557 


Emulsion, 19, 125, 444 


972 INDEX OF SUBJECTS. 


PAGE 
Emulsion theories of fat absorption, 449, 457 
Emulsive ferment, ; ; i 448 
Emydin,. ; : ; : paretoD 
Enamel, : : : . : ee alae 
Encephalin, Fre Un) 18720) 
Endosmometer of Dutrochet, : . 278 
os », Vierordt, . ‘ wu2is 
Endosmose, . : : : hi 
Endosmotic equiv alent, é : . 24 
Enumeration of blood corpuscles, OD 
Enzymes. (See also Merments.) . 312 
KN action of. (See also Zymo- 

lysis>)) ie 3 : 2 4317 
re activity of, . wt 822, (325 
s chemical nature of, s . 316 
3 classification of, . 326 
ie digestive, : 312, 326, 327 

Bs gastric, 326, 330, 334, 350, 532, 542 
543 
5 intestinal, 341, 397, 398, 556 
& isolation of, . - i « | 313 
5 mechanical precipitation of, . 314 


x pancreatic, 314, 326, 336, 340, 369, 
at 443, 551 


salivary, on) S265 , 397, 503 
Eosinophil cells}, . ; : a WSs 
granules, ; an 04: 
Epithelium, ‘absor ption by, 435, 436, 486, 488 
‘3 cutaneous, . 685 
Ss in fat absorption, 449, 451, 454, 
457 
fs gastric, . ; 7 ose a2 

3 influence of, in absorption 
of albumose, . é . 440 
5 intestinal, : ‘ . 554 
5 mammary, - . 662, 665 
~ pancreatic, : ; ww O46 
BA proteids of, 84 
: renal, 639, 640, 647, 652, 659 
6 salivary, FAM 

- vascular, influence of, on 
coagulation, . ; . 180° 
Equilibrium, nitrogenous, . r toyyfils reid 
BS nutritive, : ; eS eyfll 
Equivalent, endosmotic, . ; 5 fis 
Erythrocytes, . : : - 5 Algal 
Erythrodextrin, . : : : 16, 395 
Er i cae tep lone 3 : ; eg i! 
Erythrose, . d : 3 : 2 
Esbach’s reagent, . : J 5 US 
Eserine, action of, on sweat secretion, s1)4679 
Esters, . : 5 : - sol) (24, 159 
Ethal, ° 20 
Ether, influence of, on body temperature, 821 
Ethers, glyceric, . : : : ell 
Ethyl alcohol, ; - : : . 470 
Ethylene lactic acid, . : : . 106 
Ethylenimine,  . ; : sy 994 
Ethylidene lactic acid, : ae LOGS Vali?) 
Ethyl-pyrrol, : - fimo 
Evaporation in heat regulation, : 851 

Exchange, respiratory. Sce Respiratory 

exchange. 

Excretine, . 474 
Excretives, ur inary, characteristics of, . 635 
Excretoleic acid, . : : : . 474 
Exosmose, . 273 
Expiration, influence of, on lymph flow, 300 
cr air of, : ; : 754, 774 
= volunie ot, . : ‘ . 748 


PAGE 

209, 214, 216, 234, 
239 

95, 100, 110 
. 946 


Extinction-coefficient, 


Extractives of muscle, 
Extract of pituitary, 


53+ 99 SUprarenall: 950, 951 

sales 5) cuyroids : . 943 

Extracts, digestive, 315, 329, 325, 336, 337, 

542, 552, 557 

Eye, chemistry of, : c : = ealeal 

FACES, : : : 5 

7 alkaloids i IN ke 3 Sap Do 

»» amount and consistency of, . 472 

;, colour of, : : : 472 

Bs composition of, ‘ : . 473 

»» during inanition, . ’ 5 1G 

», heat of combustion of, . . 834 

», pigments of, . : ; . 388 

wo pereaction iol, ae ‘ ‘ . 473 
Fasting. See Jnanition. 


Fat- body, ; : . 934 
Fat formation from carbohydrates, - 931 
fatty acids, . > BBR 
“9 5, glycogen, 924, 935 

»»  proteids, . 902, 933 

Fat- splitting ferments, 160, 325, 326, 336, 
339, 443, 448, 553 


+e] 29 


Fatigue, relation of lactic acid to, . 108 
F ats, : : iy 2) ays 
5, absorption of, 5 ‘ . 443 
= a channels of, 5 22262 
a a emulsion theories of, . 449 
+ a fatty acid theory of, . 454 
as 7 influence of bile on, 369, 392, 
459, 461 
3 Pr »> 99 Pancreatic 

juice on, 459, 461 
+ be solution theories of, . 451 
,, action of bile on, . : - . 444 
5 5 on bile secretion, . . 566 
* Fr pancreatic juice on, . 443 
33 F steapsin on, . =» B20 
,, bacterial digestion of, 471 
» of bile, , 370371, 390 

, 53 blood plasma, - 159 
y> 9) bone, : ‘ : , = Salih 
53) Acarbonfof =. ; : , werOre 
», of cells, : . 82, 83, 84 
53) ea bcliyle: : P ; : . 188 
>> » colostrum, 127, 129 
,, decomposition of, 19 
A. amidiet, : : 872, 876 
on digestion of, : : aeito 


444, 557 


¥ emulsification of, . 
834, $35, 887, S74, ae 


», heat value of, 
», Of lens, 

” 9 liver, 

5s "15; Marrow; 


85, 901, “7 
19 


vy 55 Meat: A . , 3 3 96 
he metabolism of z . 930 
Bf £ influence of liver on, 935 
"of milk, 19, 125, = 133, 664, 665 
. , muscles}: , 95, 100, 105 
+> 5) nervous tissues, ' . 116 
» neutral, . : 18, 19 
,, nutritive value of, : E . 881 
,, oxidation of, : - ents. 
» pigment of, . : : eieeze, 
Pot retinay ye : : é sek 


aH (3, Sebmy es - : . 674, 675 


— Se 


INDEX OF SUBJECTS. 


PAGE 


Fats of sweat, 671 


973 


PAGE 


Fermentation of lactose, 12, 132, 334 


>> 9) Synovia, i SSS | i ;, maltose, . i = 
+> 9) synthesis of, 893, 899, 93] | i micro-organisms in, 312, 313 
»> 3, torpedo organ, . SRL | be of monosaccharides, ; 7 
»> >», White corpuscles,  . : s Hoe ¥ nature of, . é 2s ols 
ys) wool, 3 » O75 Pe of urine, 313, 582 
Fatty acids, : : Sue fs ‘19, 21, 444 yeast, - - | 621 
BA absorption of, 450, "454, 457 Ferratin, : : F : 2 136 
a in fat absorption, 450, 454 | Ferric oxide, : : : : aes 1 
a fat formation from, + 1931 fo sulphide, 3 ? ‘ : - 48 
a in intestines, 465, 471 Fibrin, , ; : 153, 166 
3, nutritive value of, 881 ;, absorption of pepsin by, 404, 542 
cA in proteid decomposition, 29, 34 » of chyle, : : aSPEES 
x3 ,, Skin secretions, 672, 674 | ,, digestion of, . . 333, 404, 420 
, ,, thyroid, \ : 88 | ,, ferment, 82, 83, 146, 160, 168, 170, 
#5 ne torpedo organ, s hte 175, 179, 319 
»» urine, : : > 615 ;, formation, factors of, 178 
Feathers, red pigment ors : a ail », heat value oft a R 834 
skeletin of, . ; . =) ED ;, leucine and tyrosine from, 452 
Fehling’s test, 7, 610 ,, of lymph, . 182 
Fellic acid, : : 373, 381 >,  myogen, . : : ; MHTIGS 
Ferment or ’ Ferments, action of, on myosin, . : 5 HE 
glycogen, . : : = lS Fibrinogen, . 161, 163, 164, 179 
sf amylolytic. See Feriments, a ie : ; . G66 175, 176 
diastatic. 53 of aqueous humour, 122, 182 
Pe of blood, 160, 929 3 Baste, : ; ; 2 eS 
5 coagulating, - 826, 553 x mechanical precipitation of, 43 
33 Ms of milk, 127, 134, 326, fe of pericardial fluid, . 183 
334, 336 3 rotatory power of, . 2 eAG 

* 5; pancreas, 326 $3 temperature of sae 
3 », stomach, . 326 | of;?: ; 4 oed3 
- diastatic, 160, 319, 322, 325, 326, Fibrinogens, tissue, 005 68, 173, 176 
338, 341, 369, 390, 393, Fibrino-globulin, . 165, 170 
398, 399, 503, 552, 556, », plastic substance, so 16S 
558, 925, 926, 929 | Fibroin, 74, 76 
35 3 of bile, 369, 390 | Fick’s law, 3 1262 
A # ;, blood, 160, 929 | Filtration, ; 3 : 280 
nv - influence of, on », through living membranes, 283 
: coagulation, 146, 147 xp in lymph absorption, - 306 
np As vegetable, BA. Se +> 9) production, 288, 290 
+ digestive. (See also Enzymes.) a », urinary secretion, - 640 
312, 326 Fishes, alkaloids in, 59, 60 
3 emulsive, . 448 >, bile of, 372, 376 
3 fat-splitting, 160, 325, 326, 336, re hemoglobin of, 187, 198 
339, 443, 448, 551 3 proteid poisons of, . : dian GH 
sa fibrin, 82, 83, 146, 160, 168, 170, ;,  Yrennin of, ; : . 304 
175, 179, 319 s,  Yespiration of, . 699, 702; 704, 730, 
5 glycolytic, of blood, 160, 161 753 
33 inverting, 10, 12, 318, 319, 342, | > slime of, 674, 676 
393, 397, 556, 558 | temperature of, . 850 
Es of liver, 594926 | Fistula, biliary, 370, 460 
i myosin, 97 | bm, ek, A . 908 
_ organised, 2 rel2 > gastric, 349, 352, 536 
- proteolytic, . 313, 319, 323, 326, 5, pancreatic, 366, 459, 547 
334, 551, 674 a parotid, . . 489 
ns 5 vegetable, 51, 54, 330, »  Pawlow, . 349 
403 : Thiry, 368, 555 
at soluble. (See also Enzymes.) 312 | Vella, t 368, 555 
4 steatolytic. See Ferments, Flax- seed, proteids of, . : ; oe ae! 
Sat-splitting. Fleischstiure, - : - 103, 420 
34 urinary, - : : 582 Flour, proteids of, F F ; nee 
urea-forming, 907 | Fluoride of calcium, . : : 78, 111 
Fermentation, action of gastric j juice on, 364 | Fluorine, 2, 77, 413 
ip of cane-sugar, : - 10 | Fetus, respire ation of, - 780 
~~ chemical changes in, 319 | Food, "ash of, : . 882 
a of disaccharides, . MNArLG 3 chemical constituents ‘of, : ; 1 
5 ,», glutaminie acid, SUNG D »; carbon of, : : : 873 
£ 5, glycogen, . : ses a composition of, 872 

4h ;, 1somaltose, ‘ = ee el », digestion of. See Digestion. 

‘s lactic acid, sel, 2G », heat value of, 834, 835, 837, 874 


974 

PAGE 
Food, influence of, on bile secretion, 565 
Bs 3 ,, body temperature, 809 

a “5 », gastric secretion, 
540, 545 

Le 5 ,, intestinal secre- 
tion, 555 
” oe) 9 milk, . 664 

iy a »» pancreatic secre- 
~ 5 se tiOn. 551, 554 

i \. », Tespiratory  ex- 
change, . 717,721 

53 - ,, Salivary scretion, 
490, 491 
55 ro  ULING,. OAD OD OU, 
593, 630, 632 
;, nitrogen of, 873 
3 putrefying g, alkaloids of, 59 
s» special constituents of, 878 
», sulphur of, ‘ 563 
vegetable, in diet, 472 


Formic acid, 5, 19, 31, 34, 66, (bE 117, 133, 


615, 672 
Formose, . : : 2 . - 5 
Fossil bones, 111 
Fredericq’s aerotonometer, 776 
Frog, cutaneous respiration of, 723 
,, fat-body of, ‘ 934 
> gastric glands of, 524 
;, hemoglobin of, 193 
a mucinogen of, 1 ie 102 
55 pepsin of, . 330, 533 
5» Tespiratory exchange of, 703, 709, 710 
», skin absorption in, : . 690 
5 4, glands oof, . 681 
Fructose, . 2/6, 12 
Fruit gum, . . 612 
Fumarie acid, 34 
Fundus of stomach, 534 
Fungi, chitin in, . : he e: 
Funke’s method of preparing hemo- 
globin, . ; 194 
Furfurol test, 608 
Fuscin, 121 
GADININE, . : : ‘ “~ , 60 
Galactonic acid, . ; : ¢ ‘ 4 
Galactosazone, . : : : 8, 612 
Galactose, 457,10, LO; ol Gs LO E20 


Gall stones,. 383, 386, 387, 


Ganglia of salivary glands, 480, 482, 484, 523 
ss 3, Stomach, : : . 538 
Ganglion, inferior mesenteric, 550 
ee otic, ‘ 482 
9 semilunar, 5 BELL 
Ee sublingual, 480, 481 
s5 submaxillary, 480, 481 
superior cervical, 484, 523 
Gases of alimentary canal, 728 
s> >; arterial blood, 760 

»> 9, blood. See Blood gases. 
i a9 206s “plasma; 157 
ss >; cutaneous respiration, 726 
ces) Lymph, . . 183 
ein. warnitke, 129, 130 
ere muscle, 110, 911 
», Tespiration of different, : dD 
Pr ofsaliva, 3 . 9346, 347, 504 
ss 3) secretions, tensions of, . . 783 
5G) sou berums 157 
33. os -Venous blood, 762 


INDEX OF SUBJECTS. 


PAGE 

Gas-pump, . . 759 
Gastric absorption, . 482, 541 
sy wuenzyes) - 326, 330, 334, 350 

wiper listulass ie 3 349, 352, 536 

39 glands, cells of, 531, 532 

3 . juice; : 349, 536 

a ;, acid of, 351 

5 », action of, on bacteria, 364, 402, 
463 

5 Pe 5»  Cane-sugar, . 398 

“ He butyric acid of, 3) BEG) 

5 5, composition of, 354, 544 


33 
Gelatin, 
be) 
> 
> 
99 


9 


”  ferments of, 326, 330, 334, 350 
hydrochloric acid of. See 
Hydrochloric acid. 


;, lactic acid of, . 351, 355 

,, methods of obtaining, 349 

,, phosphoric acid of, . - 356 
», Variations in, during diges- 

tion, 544 
secretion, histological changes 

during, : - 531 

53 influence of nerves on, 537 


” ” ” peptones on, 541 
=; ;, on urine, 359 
+ latent period of, - 549 


af local stimulation of,. 540 
mechanism of, 531 
70 


alkaloid from, ‘ : A 
derivatives of, ; . ol s2yae 
digestion of, . 3 : 
from muscle, : 
;, nervous tissues 
nutritive value of, 
from organs, . 


876, 878 
: 85, 88, 92, 121 


. ,, torpedo organ, . «110 

a peptones, 70, 429 

tyrosine and leucine from, 425 
Girgensohn’ s method of separating pro- 

teids, - : = 40 

Glands, albuminous, ‘ ‘ 3 477, 503 

;, | albumino-mucous, 478 


Gliadin, 
Globin, 


Globulin or dino aici nea 


bed 


of Brunner, : é : 
cardiac, . . : . 832,536 


muco-albuminous 
mucous, salivary, : 
pyloric, . . 532, 534, 536 
salivary. See Salivary glands. 
sebaceous, 5 - 
of skin, electrical changes i Tes 
thyroid. See eyes gland. 


chemistry of, 85 
demilune, A > 478 

ductless, influence of, on meta- 
bolism, ‘ i é 937 
during inanition, 890 
of frog’s skin, . : : . 681 
gastric, . : : . 531, 532 
Harderian, 675 
heat production i in, . : , . 843 
lachrymal, t 4475 
mammary, : - 124 
metabolic activity of, . 895 
mixed salivary, F by SHG 
477, 503 


674 
681 


53, 54 
26, 244 
49, 895 
of aqueous hum- 

our, : . 


39 


122 


INDEX OF SUBJECTS. 975 


PAGE 

Globulin or Globulins of blood plasma, 161, 
163 

” sis ,, cells, 81, 82, 84, 87 

” 9 5, chyle, . S183 


coagulation-tem- 
perature of, . 43 


3 ” 


an an from fibrin, wo 167 
5 a of intestinal juice, 557 
” 9 ,, kidney, 2 
ap ar ,, lens, 123, 124 
a a ,, liver, 5 tte 
+e , ,, lymph, 182 
+ ss », milk. See 
Lactoglobulin. 
” aE »» muscle, . 97, 98 


,, nervous tissues, 118 

precipitation of, 
bysalts, . 42 

of proteid diges- 
tion, 405, 416, 420 


y a5 3, serum. See 
Serum globulin. 

a iS » Spleen, . 6 tl 
bs " ,, torpedo organ, 110 
AE ¥5 ;, urine, 604, 605 
33 vegetable, . 51, 54 
Globuloses, ‘ 50 
Glomeruli of kidney, 639, 641, 652, 655, 659 
Glow-worm, phosphor escence of, : . 780 
Gluconic acid, ; : ; su4yi6 
Gluco- proteids, iG 64, 67 
Glucosamine, 9, 75, 85, ‘115 
Glucosane, . : ; : 6 
Glucosazone, P ; 8, 608 
Glucose. (See also Dextrose.) 2) 6s 15, 16 


», . from proteid decomposition, . 30 
Glucoside, theor y of proteids, : eure 64 
Glutaminic acid, ZO IB2 BOs Ml las 


421, 426 
Gluten, : . ‘ 53, 333 
F ferment, . ; ‘ : = 58 
Pepe eIDIIN ss | ers ¢ ‘ é 5 ae 
Glutenin, . F P ‘ : 5. DA: 
Glyceric ethers, . - : oy, ollt 
Glycerides, . - ; - 17, 120 
Glycerin, : = Uys ‘18, 19, 882 
Glycerol, . 18 
Glycero- phosphoric acid, 21, 22, 118, 160, 471 
Glycerose, . 2 
Glycine. (See also- Glycocine and Glyeo- 
ae.  .. 378, ee 668, 892, 893 
Glycocholate of soda, . . 371 
Glycocholic acid, . 372, 373 
“A 5 preparation of, a aired! 
», properties of, . Seto 
Glycocholonic acid... 375 
Glycocine, °31, 32, 71, 42; "5, 76, 378 
+3 of muscle, 95, 103 
Glycocoll, 373, 378, 469, 470 
iP synthesis of, 379 
Glycogen, : 3, 4, 13, 14, 834 
35 action of enzymes on, . 326, 397 
5% of cells, 82, 83, 84, 158 
bf 35 embryo, < ; : - 918 
ff fat-formation from, . 924, 935 
45 formation, . : 916, 922 
+ i. from proteids, 901, 905, 
919 


a Bs influence of pen- 
tose and mannose on, 


PAGE 

Glycogen, of kidney, . 92 
Ay », liver, 85, 569, 917, 918, 919, 922 

i Pelymphy. ee 2 LLS2 

wn », Muscle, 95, 100, 104, 110, 911, 
915, 917 

i ,, notochord, . , =) ls 

A »» placenta, . ; : . 918 

a Fs Dlamits; sets ‘ ; RPA 

rs », plasma, . : ; 2 Ube) 

- 5, Spleen, . : ; od 
synthesis of, - : coe 
Glycogenesis, ; : C 22 
. Bernard’s theory Gin c . 922 
Glycolic Cll ae. : 5, 673 


Glycolytic fer ment of blood, 160, 161, 929 
Glycosuria, alimentary, 436, 609, 881, 945 


3 pathological, 610, 880, 920, 926 
Glycuronic acid, . 5, 115, 469, 608, 610, 613 
Gmelin’s test, F ; : . 9385, 629 
Goat’s milk, : : ; : sO 
Goose bile, . ; » Bfdnond 
Gorgonia cavolinii, iodine i in, : 5 80 
Granules, secretory, gastric, - . ddl 

A 45 intestinal, . 5 py! 

it i mammary, . . 668 

3 a pancreatic, . . 546 

ia salivary, : . 479 


39 
Grape-sugar. See Dextrose. 
Griinhagen’s method of See pro- 


teolysis, : . c ; . 324 
Guanine, . ; F ‘ ; 60, 596 
», from nuclein, . : . 66, 67, 98 

ce 5» pancreas, : . ay 8 

a retina, 0 : : Be IPA 

a am sitestis; - : 5 RB 

= ,, thyroid, . i 88 
urine, 596, 637, 653 


Guinea-pig, admaxillary gland of, . 476 


; hemoglobin of,. 193, 194, 198, 
204, 205, 206 

Gum, . ‘ : ive 14 
», animal, +4 16, "62, 65, 126, 133, 158, 
613, 665 

5) arabic; : : : : a G6 
eS MeRe balls r . , F ee als 

;, wood, : : : j be a 
Gummose, . 7) OZ 


Gunzberg’s test for hydrochloric acid, . 365 


H2&MACYTOMETER, . ‘ : 5 st) 
Heemataérometer, 0G 
Hematin, 207, 236, 243, 246, 250, 388, 473, 
563, 622 
carbonic oxide, . : 3 200 
a hydrochloride, 250, 252 
* Pe spectrum of, 254 
38 iron-free, . : = . 25] 
3 preparation of, . e » 250 
properties of, . 250 

a reduced. See Homochr omogen. 
spectrum of, : ° 5 ok 
Hematinometer, : : : BANG 
Hematocrit, 148, Lo0s 27 
Hematogens, - 68, 885 
Hematoidin, A PAO: 384, 389 
Hematoporphyrin, 246, 251, 256, 258, 382, 
389 
3 preparation of, =. Ways: 
br properties of, . 259, 626 
95 spectrum of, . 260, 626 


976 
PAGE 
Hematoporphyrin of urine, . 618, 622, 625, 
629 
Pa 5, Separation of, 625 
Hematoscope, . : : : . 210 
Hematuria, : : : d . 629 
Hemin, ; ; } : o 25038252 


crystals, . ‘ ; . 252, 253 
236, 243, 250, 254, 629 
carbonic oxide, 240, 241, 


29 
Hemochromogen, 


29 


257 
oe nitric oxide, . 5) ure! 
on preparation of, . - 255 
33 properties of, . 255 
<3 spectrum of, 251, 255 

43, 61 


Hemocyanin, : 

Hemoglobin. (See Hes Oxyheemoglobin, 
Reduced hemoglobin.) 61, 
1538, 155, 185, 229, 834 

absorption of carbonic acid 
bys RaRlifAS) 
” ” >» Oxygen by, 167 
albuminous residue of, 248, 244 
of animals, 185, 193, 198, 
199, 201, 202, 205, 
206, 225 

carbonic oxide. See Car- 

bonic oxide hemoglobin. 


* compounds of, . 237 
» 53 », With acety- 
lene, 242 
” 53 Se carbonic 
acid, 242 
” , >, cyanogen, 242 
» a 3) >) hydro- 


cyanic acid, 241 
connection of, with bile 


pigments, . . 388, 389 
8 crystallisation of, 43, 193, 194, 
203, 232 
3 decomposition of, in liver, 901 
% digestion of, .. : . 428 
3 distribution of, F . 186 
MS estimation of, . : = lol 
- formula of, ; : e427 
7 influence of, in bile secretion, 567 
.< iron of, . . 201, 768, 885 
3 of marrow cells, : . 84 
* ,, muscles, ; 97, 99, 187 
- nitric oxide, . é » 24 
i oxygen capacity of, . 768 

af reduced. See Reduced 

hemoglobin. 

we relation of, to stroma of 
corpuscles, . : . 188 
A of spleen, : } Teele 
= sulphur of,” i. : 5 Ale 
in urine, , : 5 GEN) 
Hemoglobinometer, ily iss? 
Hemoglobinuria, . : i H en 029 
Hemoscope, . : : : SAK 
Hair, fat in, : : : : avg 17 
Haptogen membrane, . : é ~ 125 
Harderian gland, 3 : ‘ Sones 
Hare, arctic, 37, 173 


Heart, heat ‘production by; #: : . 842 


Heat, ‘animal, : 785, 882 
centres, : a 854, 858, 862, 865 


5, coagulation of proteids, 42, 43 
5, of combustion, . 884, 837, 874 
» effects of, on body, 814, 823 


INDEX OF SUBJECTS. 


PAGE 

Heat loss, regulation of, : : . 850 
A Salen by. skin, : . 850, 855 
», production in cold- bloodedanimals, 849 


j ¥) by foodstuffs, 834, 835, 837 
oA a in glands, 516, 843 
Bs \ in heart, . j 842 
MM a in intestines, . . 843 
A Ae in liver, . . 843 
* 5¥ measur ement of, . 844 
4: a in muscles, : 840 
b. ; relation of chemical 

changes to, . 833 
5 ; respiratory exchange 

as measure of, . 847 
p. _ seats of, . 839 


831, 832, 850, 865 
in hibernating animals, 


», regulation, 


? 29 


796, 831 
- * influence of body-size 
on, . 852 
a ; nervous 
"system on, 854, 859, 
862 


» Specific, : ; ; : . 838 


», value. See Heat of combustion. 
Helico-proteid, . : - 5 at 64 
Heller’s test, : F : . 605 
Hemialbumose, 405, 409, 418 
Hemicellulose, . : i : 14, 16 
Hemicollin, . fa ‘430 
Hemielastin, 11007229430 
Hemipeptone, 405, 417, 418 
Hemiprotein, ; : : - - 405 
Henry, law of, . : : : . 266 
Hepatin, 3 : 69, 86 
Heptoses,  . . 2 
Herbivora, bacter ial digestion i in, . 465 

54 cellulose in digestion i in, | N47 1 
a elimination of phosphates Py; 79 
3 inanition in, E 888 
~ respiratory exchange of, . 709 


x sodium chloride in food of, en 

ah thyroid gland of, : : 
< urine of, 585, 601, 606, 607, 616, 
632, 634 
Hetero-albumose, 410, 412, 414, 416, 418 
Hetero-proteose, diffusibiity of, ; - 46 


Hetero-xanthin, . . - 596, 598 
Hexahydroxybenzene, . . : - 606 
Hexatomic alcohols, . -. . ‘ 4 
Hexoses,  . ‘ é : : ae i) 
Hibernation, ; : . 794, 866 
3 causes of, 797 

i; respiratory exchange dur- 
inp : : ote (10 
Hidrotic acid, . 5 ! ; POtE7 
Hippokoprosterin, : : é . 24 
Hippomelanin, . - : ore 121 
Hippopotamus, sweat of, : > . 673 
Hippuric acid, . : ; - 600 


of blood plasma, . . 160 
heat value of, : . 834 
of suprarenal body, Ae!) 
of sweat, ’ ; Br iy 


+B) 


2) 


2) 


a synthesis of, - 600, 892 
i tests for, 601 
a of urine, 


571, 572, 600, 605, 
638 


estimation of, . 601 
origin of, . 601 


39 2? 


39 2? 


INDEX OF SUBJECTS. 


PAGE 
Histidine, . ' : ; A eos 
Histohematin, . F ‘ : - 99 
Histon, : p : yo 
Hoffman’s test for tyrosine, . : . 424 
Homocerebrin, : : 119, 120 
Homogentisic ‘acid, 606, 607, 630 


Homoiothermic animals, é : . 788 
Hoof, skeletin of, ; i : ee? 
Hoplocephalus, venom of, . : = 708 
Hordein, : 5 be! 
Horn, leucine and tyrosine from, : ~) 425 
;,  skeletin of, é x : pale Oe? 
Horse, gastric digestion Ofjies 5 OS 
», hemoglobin of, 193, 194, 199, 200, 
201, 202, 203, 206, 233 
Se ranilk of, .. : PTS 
35> saliva of, . - 327, 345, 347 
,, salivary glands of, . . rays 
sweat of, . : ea Gites 
Huppert’ s test for bile pigments, : . 386 
Hutchinson’s spirometer, . : - (52 
Hyalins;  . é 2 c c aes 
Hyalogens, : ; : 61, 63 
Hydracrylic acid, 106 
Hydrobilirubin, '384, 385, 387, 389, 474, 622 
Hydrochinon, . - 606, 607 
Hydrochloric acid, - - : sic 
Rs of gastric juice, 276, 351 

”? 2? ? estima- 

tion of, 
365, 545 

re #3 ;, function 
of, 364, 463 

if FP 5, origin of, 
359, 533 

cB) ”? >, Source 

of, . 358 
rs A 5, tests for, 364 
in urine, . : . 633 


Hydrocollidine, : ; : : pe ak) 
Hydrocyanic acid, : : : ee ae! 


Ks hemoglobin, . 7 924i 
methemoglobin, . 248 

Hydrofluoric acid in urine, . : . 634 
Hydrogen, - . 2, 29, 470 
< in alimentary canal, . - 729 

41 peroxide, . : . PTE 

as respiration of, . . 739 

ee sulphuretted, 29, 32, 72, 73, 76, 
470, 473 

Hydrolysis, . : : : 319, 636 
45 of disaccharides, ‘ erl0 

:, iy fatanini wide Deri 

P in fermentation, : — aly 

iY of gelatin, . : ; HoesiO 

Fy > polysaccharides, : SUIS 

or > proteids, 31, 57, 64, 400 

re ,, Starch, 13, 14, 396 

7 lired,, Po : 3 . 582 

Hydrolytic agents, . = ale 


theory of peptonisation, . 400 
Hydronapthylamine, influence of on body 
heat, ; : ‘ J821 
Hydroparacumaric acid, 466, 467 
Hydrostatic pressure, . - : . 280 
Hydroxybutyric acid, . : : 6G 
Hyocholalic acid, ‘ 2 : 3 36 
Hyoglycocholic acid, . 9373, 376 
Hyperisotonic solutions, 142, 271, 277 
Hyperpyrexia, .. - : . 823 


OLE, 1b —=(02 


977 

PAGE 

Hypisotonie solutions, . 142, 276 
Hypoxanthine, c 2 60, 101, 591 
5 of blood plasma, . 5 UW 

a ;, kidney, . ; ee 

Rs in leukemia, - - 910 

BS of liver, 85, 86 

Re ;, mamma, . ; Ze: 

4 », milk, : : . «126 

;, muscle, 100, 101 

By ,, nervous tissues, eile 

55 from nucleins, . 65, 66, 67 

. of pancreas, . : ree g2 

P. »» Spleen, -. : AES 7, 

v3 ;, testis, - 3 «4 93 

a ,, thymus, . E Aaa OS 

x », thyroid, . j Ay Potters: 

5 ;, urine, ; : . 596 
ICELAND moss, . : ‘ : Be pul! 
Ichthin, 2 ; . x : See DS 
Ichthulin, : : 3 53, 64 
Imbibition, . . k : ; 215 
33 in lymph absorption, . 307 
Inanition, carbonic acid excretion during, 889 
5 feces during, j : 5. theif 

A in herbivora, , F . 888 

- metabolism during, . . 887 

3 muscle glycogen during, . 104 

a3 organs during, . . 2 890 

5° secretions during, c . 887 

iy temperature during, . . 889 

5 urea excretion during, . 887, 888 
Indican, : : : . 607, 627 
Indicanuria, : : F ‘ 2628 


Indigo-blue, : : : = 627; 673 
peers TEC ses ; 607, 627 
29, 47, 72, 467, 468, 473, 607 

», compounds of wvotend decomposi- 
tion, : 3 : ‘ aay AG 


», excretion of, 3 : : . 470 
A sbests.forsl : - . 468 
Indoxy]l, 468, 470, 607, 627 
5, glycuronic acid, . : ols 
_ sulphuric acid, 607, 631 
Inhibition, nervous, of secretions, 512, 526, 
548, 549 
Inogen, 5 lal 
Inor: ganic constituents. See also ‘A sh. 
i of bile, 371, 560 
st iblaods ent5S. 
be) 99 29 plasma, 153, 
157 
b] 99 body, iF 76 
5 ;, bone, 6 alia 
~ ;, cells, 82, 83 
a ;, cerebro-spinal 
fluid, . . 184 
a , food, 882, 883 
AS », gastric jJuice,. 350 
ri ,, kidney, ap 092) 
A 59. LEVER MAYS 87 
i », lymph, . 182, 286 
AS eat + 310996 
F 5, milk, 128, 129, 130, 
131, 662 
i », muscle, 95, 109 
" », nervous tissues, 116 
43 »» pancreatic juice, 
367, 368 
Pe ,, proteids, = ab 


978 INDEX OF SUBJECTS. 


PAGE 
Inorganic constituents of red corpuscles, 155 
5 5, rebina, |< me ileal 
a ;, saliva, 345, 347, 494, 
496, 498, 499, 503 
5 »» Spleen, . 5 Sf 

Bs 5; succus enteri- 
GLSs ams OOO 
5 5, sweat, 671, 672 
Fe ») Synovia, . 184 
55 », thyroid, 5. fete 
35 >> urine, 572, 630 
Inosinic acid, e : 100, 103 
Inosite, - : 16, 82, 87, 90 
,, of kidney, : : 92 
so. usp musele: : ; F 100, 105 
yy) 9 Nervous tissues, . 5 = LG 
5» 9) Spleen, : 5 3 * 792 
Fo ee LeStISen : : P . 93 
oe eer Ubiy Rola: ‘ ‘ : a7 1088 
»» 5, torpedo organ, . é pit Ls 
ees Urine). : - 606 
Insects, hemoglobin of, : : ae lS, 
»» pepsin of, : : : - 330 
», poisons of, ; eb 
5, respiratory exchange of, 702, 7038, 
710 
temperature of, . 5 RP RISU/ 
Inspiration, air of, - 754, 774 
5 influence of, on lymph flow, a” 
5 volume of, : 748 
Internal respiration, 692, 780 
», secretions, : : é - 937 
Inter-renal body, : . : Say 
Intestinal bacilli, : ; - . 470 
a contents, reaction of, 452, 464 
a emulsion, . : . 447 
2 juice, 368, 397, 398 


enzymes of, 341, 397, 398, 556 
percentage of proteids 


2) 39 


3? 2) 


Thies . : . ge 

5 secretion, amount of, . 5 iy 
x 33 histological changes 

during, . 5 sy! 


influence of foodon, 555 
5, nerves 0n,555 


39 ”? 


bed ” > 


” ” ” ” pilocar- 
pine on, 555, 
557 
Ss mechanism of, . 554 
Intestines, absorption by, 284, 302, 432, 433, 
557 
5 enzymes of, 341, 397, 398, oa 
x gases of, , eo i29 
heat production i Se : 843 
Intraglobular erystallisation, : > len 
Inulin, : : - . 4, 14 
Inversion, : ; : 10 
if of cane-sugar, 10, 398, 556, 558 
- ;, lactose, : 10, 399 
rn ,, maltose, 3 ; 10, 397 
Inverting ferments, 10, 12, 313, 319, 342, 
393, 397, 556, 558 
Involuntary muscle, chemistry of, 3 99 
Iodine, - : : : : 2 2 
», in animal tissues, 5 . - 90 
»> >, thymus, F : : 4-89 
» . 5 thyroid; : . 5 > +89 
Iodo-gorgonic acid, . a oe 24 90 
Iris) te . : : é : ee 2 


Iron, - 2,78 


PAGE 

Iron, assimilation of, 885, 886 
» in bile, : . : : » 561 
Bj gpedRCOS Ags > : : . 885 
A a LOUUS ee ‘ - : ar bikes) 
eX Gi ptood! : 2 : : . 884 
,, of hematin, 250, 258 
»> 5», hemochromogen, . 256, 258 
»> >, hemoglobin, 186, 201, 768, 885 
», in liver, . : , 86, 87, 563 
 eamilke : : : : Els? 
eS nuclei, . 3 885 
8 ave nucleo- -proteids, . 68, "69, 86, 885 
1» 95 proteids, : ; 5 25, 61 
,, urine, ; 635, 885, 886 

Tron- free hematin, : : 5 B51 
Isocholesterin, 24, 674, 675 


Isodynamic value, : . 835, 837, 875 
Isomaltose, . 4.19. sibs 397, 612, 926 
Isotonic coefficients, . - 270 
Me fluids, absorption of, ‘ . 3804 
- solutions, : 142, 270 


JACOBSON’S nerve, 343, 482, 498, 499, 506, 
508 


5 vein, . : : r - 909 

| Jaffé’s test, . : . 599, 627 
Jecorin, . . 86, 87, 91, 160 
Jequirity seed, . 3 : : - 55 
KATABOLISM, : 869, 894 
Kephalines, . : : : 3 9 
Kephir fungus, . ‘ : : of pl2 
Kerasin, : : 3 « LES TI20 
Keratin, . ; ‘ ‘ 70, 72, 473 
¥ derivatives of, - : a YG 
Keratinose, . . 5 : ‘ SORE: 
Ketoses, . : 5 : - 4 
Kidney of amphibia, : : : - 655 
,, chemistry of, 92 

$5 epithelium of, 639, 640, 641, 652, 659 

;, glomeruli of, 639, ‘641, "652, 655, 659 

6. influence of, in phloridzin diabetes, 922 

s; Nerve supply of, 643, 659 


tubules of, 639, 650, 652, 655 
Kidney bean, proteids OL eam ; erunnd 
King-crab, skeletins of, : dined & 
Kjeldahl’ s method of nitrogen- -estimation, 580 
Knop and Hiifner’s method of urea-esti- 


mation, . - . : C . _ 584 
Koprosterin, - : - : - $24 
Krasser’s reaction, : : ir AS 
Kreatine. See Creatine. 

Kreatinine. See Creatinine. 
Kresol. Sce Cresol. 
Kresolsulphuric acid, 470, 631 
Kynurenic acid, . : : 607, 638 
LACHRYMAL gland, . 475 
Lactalbumin, 124, 126, 127, 134, 139 
e carbohydrate from, srr G4 
_ coagulation temperature of, 43 
3 rotatory power of, . «ns 
Lactate of ammonium, 905, 906, 909 
Lactation, urine during, : aw bGIE 
Lacteals, conan of fat by, 457, 462 
Lactic acid, 106, 586 
a in bacterial digestion, 355, 470 
4 , blood, 106, 159, 881, 894, 905 
& £, ", fermentation, 7: 12; 126, 334 
ee »» gastric juice, . F 351, 355 


INDEX OF SUBJECTS. 


PAGE 

Lactic acid in milk, : 0 1L265.183 
‘ ;, Muscle, . 99, 100, 106, 110 

5 », nervous tissues, 116, 117 

5 »» pancreas, : F spied 2 

5 >, sweat, 671, 673 

Ar 5, urine, . 894 

e: tests for, . 5 : . 366 
Lactoglobulin, WS gts 129, 134, 139 
Lactoprotein, : olsd 
Lactosazone, bay ali 


Lactose, 4, 9, 10, 12, 126, 127, 128, 129, 132, 
399, 665, 834 


s, absorption of, . 435 

», assimilation of, 880, 881 

+3 in urine, 611, 881 
Lactosuria, ‘ f 612 
Levulose. See Levulose. 
Laiose, 5 7 
Laking of blood, 142, 145 
Lanoline, . 24, 675 
Lardacein, : ; A mul 
Lardaceous degeneration, Z ats ptahe 


Latent period of secretion, 494, 505, 549 


Lateritious deposit, 588 
Lauric acid, ‘ ; ‘ : 133 
Lauristic acid, . : : : 20 
Lead, . P é : be Na 78, 87 
Lecithalbumins, 61, 69, 658 
Lecithin, : P 20, 21 
*i action of pancreatic juice on, 463 
a3 bacterial decomposition of, 471 
»  ofbile,. 370, 371, 391, 564, 901 
8. blood, 155, 160 
= ;, cells, cave 83, 84 
= Ps chyle, . 183 
5, decomposition of, < Soe: 
- distearyl, . - : oe De, 
se of lens, ; ae l23 
es 126, 129, 133 
Ee ;, muscle, . L038 
- ;, nervous tissues, EtG, 119 
55 nutritive value of, 879 


¥ production of alkaloids from, 58 


Zs of red corpuscles, 156 
;, retina, ; 121 
es paspleen, . ; : Od 
> 5, Synovia, : 184 
53 ,, testis, ‘ 3 . - 93 

5 torpedo organ, 111 


Leech extract, 152, 174, 175 


45 93 effect of, on coagulation, 147 

», hemoglobin of, . - tse 
Legal’s reaction, 469, 616 
Legumin, 51, 333 
Lens, chemistry of, 123 
Leo’s method of estimating hydrochloric 

acid, : - : . 366 


Lethal, F . : - z ste ZO 


Leuceine, : heer oil 
eet synthesis 0 of proteids, adiaD 
Leucimide, . bpatio4 
Leucine, . ‘ sig (285497 
is constitution of, : 422 

is from different substances, 425 

bi. in decomposition of albuminoids, 71, 
73, 74, 76 
2 ,, digestion, ‘ : 437 
a ™ Kidney, . .. ‘ : asin 92 
~ », liver, . s : : =n 12:86 
>» 9) nervous tissues, 116 


979 

PAGE 

Leucine in pancreas, . : : unto 
re », pancreatic juice, . 3, Or 

3 ,, proteid decomposition, 28, 31, 

2, 34, 63 

oe ,, putrefaction, 7 470 

‘ separation of, from tyrosine, 424 

‘5 in spleen, F : : A Gi/ 

bs >, sweat, 673 

3 synthesis of, : + 421 

Be in synthesis of proteids, ; o\ 1oD 

i ,, testis, : : 5 5 ERE 

ss tests for, : 423 

4 in tryptic digestion, 405, 406, 416, 
421 

99 >, urine, - 602 
Leucocytes, 141, 152, 158, 286, 344, 440, 
450, 501, 519, 663 

HP in fat absorption, 457 

#3 influence of, on coagulation, 175, 

179 

Leucocytopenic phase, 152 


Leucocytosis and uric acid formation, 67, 594, 


"595, 596 
Leucocytotic phase, 152 
Leucomaines, : 58, 101 
Leucosin, . : : ; F se: 
Levulinic acid, . «| 43463566 
Levulose,_ . 4, 5, 7, 8, 10, 12, 5B 611, ‘917 
Lichenin, . : 14 
Lieberkihnis, crypts, : : 3 Be 
Ae jelly, . ; : ae 
Liebermann’s aia 23, 48 
Lignin, ; - - P - . 16 
Lime. (See also Calcium salts.) . 77, 87 
Lipase, - 160 
Lipochromes, 20, 122, 133, 157, 159 
Liquor amnii, fatin, . oe aly 
2 », _proteidin, . é, 24 

»,  sanguinis. See Llood plasma. 
Lithium, . : 2 
Liver, amylolytic ‘ferment of, 925, 926 
», chemistry of, . Bre 


be extirpation of, 105, 905, 908, 909, 910 


fain 17, 85, 901, 935 
Le formation of urea in, . . 906 
Hs se uric acid in, . 909 
», glycogenof, 85, 569, ‘917, 918, 919, 
922 
;, heat production in, 843, 896 
;, influence of, on coagulation, 178 
a us ;, fat metabolism, 935 
e 93 », proteid meta- 
bolism, . - 900 
;; hitrogenous metabolism in, 906 
,, nucleo-proteid of, . 3 a 1 
;,  proteids of, 24, 85 


urea- forming ferment of, : 
Living proteids. (See also Bioplasm. ) 38, 80 
Lizard, respiratory exchange of, patiati 


Lung catheter, 774 
Lungs, alveolar surface of, 754 
;, influence of, on coagulation, 178 
Lupino-toxin, . - ; ; aloo 
Lutein, ; : : 20, 95 
Lutidine, : ; = Po: 
Lymph, ‘absorption of, 302, 306 
;, amount of fat i ip) : jnellZ 

as ee proteidsin, . sored 

;, chemistry of, Saleh! 

,, coagulable, . 164, 168 


980 


PAGE 
Lymph, corpuscles of, . - : Hat 


», dextrose in, : 6, 182 
= functions on ; : 4 Slo) 
> gases of, . f 5 : S Ose 
As hearts, 5 3 . 301 


i influence of aor tic obstruction on, 292 
blood pressure on, 299, 

300 
capillaries on, ~ +296 
hydremia on, 5 SB} 
lymphagogues on, 293, 


2) 99 


297 

aA 4 muscular contrac- 
fLONKONs ee . 3800 
a 7 plethora on, . . 293 


respiration on, . 300 
venous obstruction 


9 99 


be) 2? 


on, 55 5 se 201 

;, movement of, . : . 299, 300 

pe Pressure Of-muaa. = : 5 299 

», production of, . 285, 286, 298 

» Of salivary glands, . : - 510 

# », thoracic duct, . . 290 
Lymphagogues, 290, 293, 297 


Lymphatic glands, chemistry of, 81, 88 
Lymphatics, absorption by, . 302, 433, 610 
Lysatine, . : . 33, 426 


Lysatinine, 29, 33, 72, 73, 421, 426 
Lysine, 29, 33, 12, 73, 421, 426 
MAcKEREL, alkaloid in, ee 359 
Magnesium, . é 5 BP Tiss teil). 
5s palmitate, | ; : JAS 
x3 phosphate, A657, Soe alls 
153, 157 
“5 salts in body, . : TRATS 
ae >» 9) proteids, : Mi {26 
- 35 Oloumineste : . 634 
53 stearate, . ; 3 5) Oks} 

53 sulphate, precipitation of 
proteids by, . : . 42 
Maize, proteids of, : : : . 54 
Malaminic acid, . : : ; god! 
Malic acid, . : : : ‘ . 673 
Malt diastase, 393, 394 
Maltodextrin, F 16, 396 
Maltosazone, 11 
Maltose, 4, Ue 9, 10, 13, 15, 394, 395, 396, 
397, 398, 916, 926 
he absorption of, : 5 bes 
a assimilation of, . - 880, 881 
5 heat value of, : 6 . 834 
a in urine, © 4 <steill 
Mammalia, cutaneous respir ation ‘of, - @20 
5 frequency of respiration of, 753 
* heemoglobin of, . : 187 
5 respiratory exchange of, 706, 709 
af skin absorption of, . . 688 
59 temperature of, . ; ened 
urine of, . ; 637 
Mammary glands, 124, 662, 665 
Manganese, . 2; 78, 87 
Mannite, 4, 6,7 
Mannonie acid, uduG 
Mannosaccharie acid, : 4 
Mannose, ; SON aOR 785116 
Mannoso-ce ‘Hulose, : ‘ : eG 
Marrow cells, proteids off) . ‘ oe 
5 BO g ig ue 
i. nucleo- proteid of, : = 5 ceil 


INDEX OF SUBJECTS. 


PAGE 

Mastication, influence of, on salivary 
secretion, : 490, 491 

Max Schultze’s method of Ereperng 
hemoglobin, . ; 194 
Meat, constituents of, 96, 874 
Mechanical Snes ‘ : : 30275 
Meconium, 473, 474 

Medulla, salivar y " secretion after pune- 
ture of, é : . ‘ ! . 484 
Medullic ‘acid, - 3 : : ‘laa oS) 
Melanin, . ; < pale 
Melanotic sarcoma, iron in, : = hs) 
Melebiose, . : 4 ; wee L2, 
Membrane of Descemet, 64, 121 
Membranes, filtration through, - 280, 283 
3 permeability of, 264, 2738, 274, 
276, 296, 308 
3 semipermeable, : 264 
Membranin, : f 64, 121 
Mesenteric ganglion, inferior, ‘ rr550 
Mesostate, . F é Ber536 
Meta-amido- benzoic acid, : : He 36 
Metabolism, . : A . 868 
a carbohydrates in,” | 2 SOWA SOT'b 
3 of carbohydrates, c 616 


action of pan- 
creas on, +. ~927 


9? 29 9? 


ble conditions affecting, . . 869 
‘. contact changes in, . - 870 
ea during inanition, . ce isi 
Oftatiannes : : 5 380) 
A. ;, influence of liver on, 935 
se », of foetus, : 732 
Ke influence of assimilated pro 0- 


teid on, . 903 
,, ductless glands 

Ones Sr rUBYe 
ne 5, Spleen on, 3 Sha’) 
,, temperatureon, $48 
5, alter section 

of cord, 859 


i) 9 9 


Pr katabolism in, . 894 
< muscular, 895, 902, 904, 911, 

915, 918 
os nitrogenous, in liver, . 906 
- a in tissues, . 896 
iy oxidation in, . : . 894 
A of proteids, : j . 897 


influence of liveron, 900 
;, muscular 
activity on, . 911 


+) 29 


29 9 2? 


Ai reaction in, . : -_ 870 
ee synthesis i Wm, 6 893 
- of tissues, relative ‘activ- 
ity, : : c 2895 
if urea in, . K E - 906 
. uric acid in, . ; . 909 
Metacasein, . : ; : f ee |7/ 
Metalbumin, j 9 : ; Leones 


Metapeptone, ; 3 : . . 403 
Metaphosphorie acid, . E : Hong 
Methemoglobin, . “hale . 248, 244 
compounds of, . 248, 249 


29 


= oxygen of, . : . 247 

$4 reactions of, 2 . 246 

45 spectrum of, . . 246 

55 in urine, . : - -629 
Methal, : 20 
Methane, 


: 16, 470, 471, 472, 473, 729 
Methylenitan, . : 5 


INDEX OF SUBJECTS. 


PAGE 

Methyl glycine, 598 
»,  glycocoll, 427 

»,  glycocyanin, . 598 

;»  indol, 469, 607 

ss Merecaptan, : : . 470 
pyirol, . - - ol 
Micellar theor y of peptonisation, . 400 
Micelli, 400 
Microchemical methods, 66 
Micrococcus uree, 601 
Milk, alkaloids in, 59 
», Of animals, = 6130 
7) ash of, 662, 885 
e carbohydrates of, 2 71382 
», chemistry of, 125 
>, coagulation of, 134, 138, 334 


coagulating ferment of, 


127, 134, 326, 


334, 336 
», composition of, 874 
», constituents of, 126 
>», .of cow, 129 
», discharge of, 667 
», effect of boiling on, el 26 
= , tats of, 17, 19, 138 
55 gases of, 129, 130 
», globules, 125 
», heat value of, ‘ . 834 
:, human, 127, 133, 138 
;, lime in, ; - 886 
5 phospho- carnic acid of, 104 
»,  pigeon’s, 675 
», plasma, = ls 
tt. proteids of, 24, 134 
>» reaction of, ‘ il 26 
>» secretion, action of atropine on,. 664 
35 ¥ +> >, Pilocarpine on, 664 
. a cells during, 662, 665 
- i formation of organic 
constituents in, 665 
ze x influence of diet on, 664 
2? 3? 3? 33 nervy 0 u Ss 
system on, 663 
- oA mechanism of, - 662 
5, sugar. See Lactose. 
Millon’s reaction,. 7 , ee A 
Mineral constituents. See Inorganic 
constituents. 
Minimal air, 5 (Ee 
Mixed saliva, 344, 348 
55 salivary g glands, 477 
Molar salivary g gland, 476 
Molecular conductivity, 261 
nA weight of albumin, 26 
4 3 ;, albumoses, 27 
ss 5 ;, antipeptone, . 27 
- ss ,, deuteroproteose, 46 
be +>  97,hemoglobin,. 198, 203 
56 ‘3 », peptone, » 46 
a +> 99 proteids, 26, 27 
- x Ltt paca Z 46 
Molecules of proteids, - 26, 45 
Mollusca, hemocyanin of, 6 
a hemoglobin of, 187 
e muscle of, oD 
a respiration of, 702, 753 
skeletins of, . san ee 
Monacetin, 18 
Monobromacetic acid, 34 
Monobromobenzoic acid, 34 
Monosaccharides, 4,7 


| 


981 
PAGE 
Moore’s test, : 7 
Morphia, influence of, on mn body tempera- 
ture, A : - a) sis74ll 
Mountain sickness, : 738 
Mouth, temperature of, 787, 788, 824 
Mucedin, : : 53 
Mucie acid, : 4 
Mucilage, 14, 16 
Mucin, : 61, 84 
Pn Of bile: 370, 371, 569 
a ;, bone, F asi 
- decomposition of, ay 62 
,, of epithelial tissues, . stayy Of 
ani, suteeces! 473, 474 
2» 9, Kidney, = oy 92 
sy ae ver; 85, 569 
ae lymphatic g glands, Ae asls 
a5 », Marrow, - are geil 
oes METSALLVaate 343, 344, 501, 503 
>> >, Salivary glands, ; 92 
s> 35 Skin secretions, . 673 
3) 9; Succus entericus, . 368, 369 
io »> Synovia, 184 
Ng ey5 LOT rpedo organ, 110 
* ;; urine, 604 
;» Vitreous humour, ‘ lea 
Mucinogen, . 62, 92, 123 
Mucinoids, : : . “i768 
Muco-albuminous glands, ‘ 478 
Mucoids, ~ 60; 63, 121, 123 
Mucous cells, 477 
be glands, salivary, 477, 503 
;, secretion of mouth, . 344, 348 
Mucus, : = lis 84, 85 
Mule, milk of, 131 
Murena, poison of, 55 
Murexide test, +) p92. 
Muscarine, , : : ‘ 60, 472 
G; action of,on salivary secretion, 513 
55 ;; Sweatsecretion,. 680 
Muscle albumin, coagulation tempera- 
ture of, 45 
chemistry of, 95, 109 
;> creatine in, 100, 904 
,, digestibility of, > Oe: 
», extractives of, . eae L005 110 
;petatiot. 17, 95, 100, 105 
pjmbeezases of, SUNOS al 
» glycogen of, 95, 100, 104, 108, 110, 
911, 915, 917 
s, hemoglobin of, 97, 09, 187 
», heat production in, . . 840 
during inanition, 104, 890 


»,  ilmorganic constituents of, . 109 
,, involuntary, chemistry of, 99 
;, leucine and tyrosine of, « 425 
», Metabolic activity of, 895, 904, 911, 
915, 918 

», plasma, : 95, 96 
:»  proteids in, 24, 95, 96, 97 
», in proteid metabolism, 902, 904, 
911 

5, reducing power of, 782 
“3 oF substances of, 110 
5, respiratory exchange of, 840 


»,  sareolactic acid of, 


serum, 
» sugar, 
> urea in, 


95, 99, 104, 106, 


110, 911 
96 


100, 105, 110, 606 


100, 102, 904 


982 

PAGE 

Muscular contraction, chemical changes 
during, . 0S 

A: influence of, on 
lymph flow, 300 

- 5, proteid meta- 
bolism, 911 


5 ;; muscle glyco- 
gen, 110, 915, 918 


Musculin, . : 97 
Mussel, alkaloids i ins) a 59, 60 
;,  skeletins of, ; : : eS 
Myelines, : 119 
Myogen, 98 
55 fibrin, ; 98 
Myo- -globulin, 97, 98 
Myo- hematin, 5) SE 
Myo-proteid, 98 
Myosin, : 95 
ss UGferment, \- 97 
= =) fibrin, 98 
», vegetable, 53, 54 
Myosinogen, : : Woy: 98, 99 

$3 coagulation temperature 
of, 43 

es mechanical precipitation 
of, : : Ss 40 
Myosinoses, . 50 
Myricin, 20 
Myricyl alcohol, palmitate o of, 20 
Myristic acid, 20, 133 
Mytilotoxin, 60 
Myxcedema, 938 
NEGATIVE phase, of Syl ee 146, 173, 176 
Neossidin, : St se} 
Neossin, 5 63 
Nerve or Nerves, auriculo- -tempor al, 482 
», buccal, - 482 
>,  chorda tympani, f 479, 519 

»  chordo-lingual. (See also Chorda 
saliva.) 479, 505, 509 
ee stabi: = 

A influence of, on salivar y ‘secre- 
tions, 343, 487, 493, 494, 506, 
519, 525 
;, of Jacobson, 348, 482, 498, 499, 
506, 507 
, >, Kidney, : . 6438, 659 
>>» Jachrymal gland, 475 
SGI. orbital eland, 482 
5» 5, parotid ‘gland, 482 
» 3; Salivary glands, 479, 483 
ee se ed cranial, 479, 482, 
493, 504 
section of, 519 


if ns sympathetic, 479, 
483, 494, 522 


39 39 3° oP) 


»» Secretory. See Secretory nerves. 526 

,, section, effect of, on muscle gly- 
cogen, : . 105 

», of skin secretion, : 676, 677 

5, small superficial petr osal, 482 

», of sublingual gland, 479 

el submaxillary ¢ gland, 479 

5, trophic, of salivary clands, 526, 528 

;,  vaso-constrictor. See Vaso-con- 
strictor nerves. 

»,  vVaso-dilator. See Vaso-dilator 
Nerves. 

Nerve-centres of cardia, 538 


INDEX OF SUBJECTS. 


PAGE 


Nerve-fibres, frigorific, . 855 
pA secreto-inhibitor y; of sali- 
vary cells, 526 
5 secretory, 526 
5 thermic, . 865 
trophie, 526 
Nerve- ‘ganglia of salivary glands, . 480, 482, 
484 
Nervous tissues, chemistry of, . 115 
“p fat of, : é 1 
hemoglobin of, 187 
a proteids of, 24, 117 
45 reaction of, 7 
Neuridine, 60 
Neurine, , 22, 60, 160, 472 
Neurochitin, s 15 
Neurokeratin, : 72, 116, es, 
Neurostearic acid, : ; : - 120 


Neutral fats, : 18, 19 

5 — precipitation ‘of proteids 

: - esl 

Nickel senotlo of proteids, - 48 
Nicotine, action of, on body tempera- 

ture, . 5 bypal 
salivary secre- 


tion, 480, 484, 515 


bed 2? 3) 


> 26 », sweat secre- 
tion, 679 
Nitrate of urea, . 581 
Nitrates of urine, . 634 
Nitric oxide in blood, 238 
35 ;, hemochromogen, 258 
», hemoglobin, 241 


Nitrites, action of, on oxyhemoglobin, 245, 


247 
;, compounds of, with methemo- 
globin, : ; . 248 
of saliva, 346 
5 55) ures 634 
Nitrogen, ; : ‘ 2, 30 
* of alimentary canal, . ~ 29 
3 alloxuric, . : 5 tye 
= of blood, : ‘ 54 G61, 7469 
¥ of chyle, 900 
elimination, 580, 876 
“ 53 during inanition, 887, 
888 
a 53 with proteid diet, 891 
5 estimation, ge s method 
of; We : Ss) Hitt, 
; excretion by skin, 672 
3 of foodstufts, 873 
- », Meat, 4 A 
: in respiration, 760, 704, 739 
of urine, 580, 637, 864, 912 
N itrogenous constituents of blood plas- 
ma, 0 
be] 329 9 body, 1 
Pe af >, urine, 580 
A equilibrium, 871, 891 
5 extractives of muscle, 100 
3 metabolism in liver, 906 
Ey tissues, 896 


NO- heemochromogen, NO- hemoglobin. 
See Nitric oxide. 
Non-nitrogenous constituents of blood 


plasma, 157 

body, 1 
“s extractives of inde 100, 
104, 110 


—— 


INDEX OF SUBJECTS. 983 


PAGE 
Nonoses,  . : : ; : ; 2 
Notochord, . : i ; ‘ ts 
Nubecula of urine, é ; : 5 SS 
Nucleic acid, ; : i : OO 
Nuclein, . Sol Ga GO 
5 bases, : : 66, 87, 88 
+ of bone, . : - : DL. 
> crystallisation of, . : » «44 
55 of feces, ‘ : ; . 473 
a », fibrin, : ; - a Ls 
5 influence of, on white cor- 
puscles, . ; - » 152 
7 iron of, . 3 F f 885 
PP of liver, . : ; 85, 86 
es », nervous tissues, . - L1G 
‘, nutritive value of, . F — yr) 
An of pancreas, . ‘ é F 3 
rp », pus cells, . : : a So 
5 ,», red corpuscles, 155, 198 
ne », testis, ¥ ‘ : «e 93 
», yeast, . : ° . : 3 
Nucleo- albumin, . b =) 6%, 428 
5 ‘of bile, 371, 561, 569 
si digestion of, F 3) "428 
Nucleo-histon, 68, 82, 604, 605 
Nucleoli, nucleic acid of, ; SS 
PP nucleins of, . : : (66 
Nucleon, : : 104, 139 
Nucleo - proteid, 61, GEN 67,181, ., 428, 
895 
5 of blood plasma, . 161, 165, 
171 
x3 », cells, . 81, 82, 84 
ns compared with colloids, 37 
= digestion of, 5 . 428 
sa of fibrinogen, : Gh 
35 influence of, on coagula- 
tion, 170, 
176, 179 
= #3 » uric acid 
excre- 


tion,. 594 
awe Lt .6 
cor- 
puscles, 179 
ee of kidney, 92 


” o) liver, 85, 86 

F 5, mamma, . - s 24 

“is in metabolism, . . 910 

* of mucus, . : eS. 

6 7 LUISCLEs 5: : . 98 

Ae », hervous tissues, Seeuulalts 

5 senuclei, 7 - e182 

54 nutritive value of, 5 7) 

rf of pancreas, . , 6, 64 

- as poisons, . : 7 ) 55 

4, precipitation of, . - 42 

ee of red corpuscles, . 5 GE 

ah 7. Spleens) ©: 87 

re », submaxillary g gland, 92 

- », suprarenal body, IROL 

3 Fen UCSLIS. ies ‘ 3) 

“ ,», thyroid, . ; . 89 

se 5, urine, 85, 603 
Nucleus, iron in, . : : : . 885 
* nucleins of, : - 66, 81 

i nucleo-proteid of, . : «| 182 
Nutrition, balance of, . : : 2 Osi: 
Nutritive equilibrium, . - : o teil 
Nylander’s test, . : : : - 610 


PAGE 

Oats, proteids of, : ; ; ne54 
Octoses, , : ; : : : 2 
Oekoid, ; ; : oy dtets, 
Oleic acid, 18, 24, 133, 456, 675 
Olein, . c : F 18, 133, 159 
Oleyl, . , ‘ : ; 2 18, 22 
Oncograph, . : : 2 . . 643 
Oncometer, . : : . 643 
Onuphis tubicola, hyalogen from, : . 64 
Ophridium versatile, sta i of, a TRL 
Optimum point, . - : . 9320 
Orbital salivary gland, 476, 478, 482 
Organetweiss, 5 eit) 
Organic constituents of blood plasma, » Abe 
” ” body, ° 1 

5 », bone, : Bala 

as », cells, 82, 83 

aes 5, gastric juice, . 350 

- ,, liver, é 85, 86 

5 5, pancreatic juice, 367, 

368 

5 5, red corpuscles,. 155 

a », Saliva, 344, 347, 494, 

496, 498, 500, 507 

5 », Spleen, . 87 

3 ,, thyroid, . ap, ee 

3 », urine, : . 572 
Organised ferments, . < : . 9312 
Organs, chemistry of, . 5 - 5 ly 
Ornithin, . ; ; ; ; 33 


Ornithuric acid, F 602, 638 
Orthodihydroxybenzene, : P . 606 
Orthonitrobenzyl alcohol, . : 5 


Osazone, 3, Se Oem Tele ‘12, 30 
- of acrose, 5 
As ;, albumin of peas, : 64 

5 ,, decomposition products of 
proteids, 30, 64 
ob », dextrose, ; : 8, 612 
os ,, disaccharides, . : 10 
Ae ;, formose, . : j - 5 
a », galactose, . ; 8, 612 
rs 5, glucose, . : : 8, 608 
5 ;, 1somaltose, ‘ : 12, 613 
a §) lactose," >! !: : : > lz 
os », levulose, . : ‘ : 8 
of », Maltose, . : : oe lil 
35 ;, Mannose, . : - 8 
5 . monosaccharides, F , 8 
a 5» pentose, 3, 612 
93 ;, Sugar of tendon- mucin, . 62 
Osmosis, 5 . 264 
in lymph absorption, ; . 307 
Bg Sen 5,8 production, —- . 288 
;, Salivary secretion, . SOL 
Osmotic pressure, . 265, 276, 308, 650 
Osones, : : ; : : « 65.9 
Ossein, : - 2 : : 70, 111 
Otic ganglion, . ‘ ; : . | 482 
Otoliths, . : : : - 8 
Ovarian ‘dermoids, P : : POND 
57 huid, mucoid offer : s« 863 
Ovary, chemistry OLN: - : 94 
Ovomucoid, . ‘ P x 63, 85 
Ox bile, 370, 373, 381, 385, 390 
»> », ucleo-proteid of, . iRESE 
,, hemoglobin of, 193, 199, 201, 202, 206 
», respiratory exchange of, . ; a MEL 
,, salivary glands of, . A : ; . 477 
Oxalate of calcium, 78, 614 


984 


PAGE 
Oxalate of urea, . . i581 
Oxalated blood, ae 165, 166, 169, uy Pere Wy. 
Oxalic acid, . , 30, 31, 34, 571, 614, 673 


Oxaluria, 614 
Oxidation in blood, 781, 895 
53 5, cells, 780, 781 

a 5b metabolism, j . 894 

a of proteids, . : ; cca ygnd 

in ip ‘ 895 

Oxy butyric acid, 928 
Oxycarnic acid, ; 103 
Oxychinolin- carboxylic acid, 638 


Oxygen, - : 2 
b> absorption of, by hemoglobin, 767 
e of alimentary canal, 729 


2 53) blood, 153, 154, 185, 229, TDi 
761, 762, 765, 768 
“ capacity of hemoglobin, 768 
3 of contracting muscle, 110 
- », methemoglobin, . 247 
- 5, milk, ; 129, 130 
5 ,, oxyhemoglobin, 236 
s respiration of, . Se ets (Ee 
»» im respiration. (See also Re- 
spiratory exchang ge, Re- 


spiration. ) 
», . respiratory, 


692, 695, 700 
185, 235, 236 


eo Saliva, |. . 346, 504 
As secretion by swimming nee 705 
» . of serum, 157 
;, tension of, in alveolar air, 774 
“ ;, blood, Soi 
Oxyhemoglobin, - 185, 193 
“e action of nitrites on, . 245, 
247 
oF amount of oxygen in, 236 
ue crystals of, 203, 205 
s decomposition of, 207, 243 
5 derivatives of, . 248 
5 diffusibility of, . 208, 207 
us dissociation of, . 774 
- elementary composi- 
tion of, . : HO 
aa preparation of, 193, 200 
55 quantitative determina- 
tion of, . =, 204. 
35 reactions of, 207, 236 
es reduction of, 3 yy 2d 
a solubility of, 203, 205 
a spectrophotometric 
constants of, 213, 223 
fe spectrum of, 208, 210 
29 oe) i) photo- 
graphic, 225 
Oxylic acid, : . : : =, 203 
Oxyphenyl alanine, : 32 
. ‘amido- -pr opionie acid, 29 
prone acid, 29, 106 
Oxy phil cor puscles, . ; 152 
PALMITATE of cetyl alcohol, : aren 20 
re ,, Magnesium, . ; 5k 
myricyl alcohol, : 20 
Palmitie acid, or 20, 24, 119, ane. 675 
Palmitin, 18, 133, 159 
Palnityl, : 18, 22 
Pancreas, action ‘of, on car 1rbohydrate 
metabolism, : 927 
ne changes in, during digestion, . 546 
a chemistry of, E : pales 


INDEX OF SUBJECTS. 


PAGE 

Pancreas, nucleo-proteid of, . 3, 6, 64 
= pentose from, 64, 612 
Pancreatic casein, sum a 
5 diabetes, . 5 927, 929 

i enzymes. (See Lnzyies.) 336 


Fs CXLLBCIS. 0s : - . 336 


me Bs activity of, 325, 552 
a fistula, 366, 459, 547 
3 juice, ; : ‘ 366 
ie ;, action of, on fats, 443 
+ i #8 », lecithin, 463 
a a3 - ;, proteids, 414 
a ah Ae ;, starch, 393 
3 ;, of animals, 367 
35 », coagulating fer ment of, 326 
a ;, composition of, SBI 
hs », emulsive action of, . 448 

5 >, enzymes of. (See En- 
zymes. ) . 336 

3 », ferments of. See Fn- 
zymes. 336 

< >, influence of, on fat 
absorption, 459, 461 
- », methods of obtaining, 547 
BS 5,  proteids of, 24, 367, 368 
56 ;, Yate of secretion of, 368 

55 s, Variations in, during 
digestion, 5 553 

5 secretion, histological changes 
during, 546 

35 [ influence of alka- 

loids 
on, 548, 
550 

”» 9 ” 3) blood 
flow on, 549 

” ” ” ” gastric 
juice on, 551 

be) 9? +B) 29 nervous 

system on, 547 
ae 53 latent period of, 549 


local stimulation of, 551 


x "5 mechanism of, 546 

- *s paral 550 
Papain, - DL, DAS Io 
56 plant, proteids of, 51, 54 


s» proteolytic ferment of 54, "403 


9? 

Papoyotin, . - . 403 
Paracasein, . : 4 . 184 
Paradihydroxybenzene, - - . 606 
Parafibrinogen, 164 
Paraglobulin, : 163 
Parahemoglobin, é 207 
Parahydroxyphenyl- -acetic acid, 606 
propionic acid, . 606 
Parakresol, : , : 29, 466, 467, 606 
Paralactic acid, . - . 106, 183, 465 
Paralbumin, j ae es? 
Paralytic secretion of pancreatic juice, 550 
55 ,, Saliva, 519 
Paramucin, . Z “ - - +, 46a 
Paramyosinogen, 97, 98, 99 

Paranucleins, i : ~ e 
Paraoxybenzoic acid, . . : 34 
Paraoxyphenyl- -acetic acid, 466, 467 

i amido - propionic acid, 

421, 423, 467 
i propionie acid, 466, 467 
Parapeptone, : : , 402, 404, 408 


Parathyroids, : : - : » 940 


@ Mee ee 


+e? 


ji en 


INDEX OF SUBJECTS. 


PAGE 

Paraxanthin, 596, 598 

Parotid fistula, 489 

Faegiand ‘of anim: als, 476, 478 

s,  herves of, F 482, 483 

saliva, 327, 343, aa shite 494, 495 

Parotids of toad, 5 6/4 

Parvoline, . : : : : PS eet) 

Payy’s test, ; 611 

Pawlow fistula, : 349 

Peas, osazone from, ; : . . 64 

Pelias berus, venom of, : : ae Hats 

Pentosanes, . ht aie : : : 3 

Pentoses, é ‘ =, Dee 

a from pancreas, 64, 612 

55 physiological action of, . : 3 

5 in urine, 3, 612 

Pentosuria, . F : fan 612 

Pepsin, 326, 33 0, 350, 358, 402, 532, 534 

»» .absor ption of, by fibrin, 404, 542 

», action of, on proteids, 326 

ee fal. animals, A , 330 
»s digestion, effects of form of pro- 

teid on, 3903 

i ty >>. 9 reaction on, . 33] 


, temperature on, 331 


2) 99 


35 estimation of activ ity of, 323 
i formation of, 542, 544 
ye hydrochloric acid, 331 
33 in muscle, ; P : Se OT 
oF preparation of, . 314 
- separation of, from rennin, 335 
Pepsinogen, 425, 532, 536 


Peptic digestion, . 401, 418, 428 
cleavage theory of, 405, 406, 


33 2? 

414, 416 
4 a proteids of, 402, 414, 541 
Peptones, 50, 51, 400, 401, 403, 405, 411, 
416, 899 
By absorption of, 437, 439 
9 of bacterial digestion, 466 
e carbohydrate from, F . 64 
eo in cells, : é 02 
te in cerebro- -spinal fluid, 184 
a diffusibility of, 45, 46 
Re elastin, ; ‘ 1 02,430 
53 of gastric juice, 353 
se gelatin, 70, 429 
+ heat value of, 834, 835 
Bs influence of epithelium on, 440 

= +> 33 injection on white 
blood-corpuscles, 152, 179 
bs molecular weight of, . 46 
* of muscle, . . Pe 
i nutritive ‘value pis 878 
53 of peptic digestion, 403, 416 
is as poisons, ; 5 Be 
. precipitants of, . 4 oie ei) 
- of pus cells, j ‘ an S83 
op of spleen, . ‘ a asks 
a of tryptic digestion, . 420 
9 in urine, 604, 605 
vegetable, . oY GIL 
Peptonisation, hydrolytic theory of, 400 
‘ micellar theory of, 400 
by superheated steam, 403 
Peptonised blood, 147, 152, 166, 174, Aides 
182 
Peptonuria, . . 604 
Pericardial fluid, 24, 183 


Permeability of blood corpuscles, 271, 277 


985 


PAGE 


Permeability of membranes, . 264, 273, 274 


rp a - living, 276, 296, 

308 

Pernicious anemia, alkaloids in, . ee) 
Peroxide of hydrogen, . : RAO 
Petrosal nerve, small super ficial, 482 
Pettenkofer's test, - 377 
Phaselin, . ec . ° ; a eA 
Phaseolin, . ; ‘ ; 54 
Phenaceturic acid, ; 470, 601 
Phenol, 29, 34, “46, 72, 466, 467 


,, compounds of proteid decom- 
position, - . : 5 ar40 


;, elimination of, . . 470 
5,  glycuronic acid, 613, 614. 
;, in urine, 606, 607 
Phenyl compounds in " proteid decom- 
position, . , ee 
Phenylacetic acid, 295 46, 466, 467, 470 
Phenylacetyl elycine, . 106 
Phenylhydrazine test, 3 8, 608 
Pheny|propionic acid, 29, 46, 466, 467, 
470, 601 
Phenylsulphuric acid, . 470 
Phlebin, ; 190, 192, 225 
Phloretin, 920 
Phloridzin, . : 920 
a diabetes, 5s 920 
Phosphate, ammonio-magnesic, 78, 473, 632 
y calcic, 76, 7itsk, Malile wales, ae io 
153, 157, 473, 633, 882 
3 magnesic, 76, 78, 111, 113, 153, 
157 
a potassic, 76, 78, 82, 87, 108 
3 sodiec, 76, 78, 118; 145, 157 
of spermine, : oe 
Phosphates i in body, . : . sninitia 
a of serum, - weniine 
Phosphocarnie acid, 103, 104, 139 
Phospho-gluco-proteids, ‘ 61, 64, 67 
Phosphorescence, : : 780 
Phosphoric aeid, D530) Tila 87, 153, 
356, 575, 632 
53 of gastric juice, 356 
35 ,, torpedo organ, iif 
Phosphorus, : . ; ‘ 2: 25 
A elimination of, 575 
i in liver, . eH AOL 
53 ,, nuclein of musele,. a 98 
5 ,, nucleo-proteid of ‘cells, 81, 84 
- ,, proteids, 25, 26 
i > vitellin, ‘ ‘ e453) 
Phrenosine, . ; : : 120 
Phycocyanin, : ‘ : ; sen 2 
Phylloporphyrin, 382 
Phymatorusin, 121 
Physostigmine, action of, on _ pancreatic 
secretion, - : : c . 550 
Phytalbumose, : ; ; ; 1) 4,53 
Pialyn, 326, 336, 


: F 339, 553 
», effect of bile on, . 339 


reaction on, 339 


92 2) 

es 33 temperature on, 339 
Picoline, . , 5 : : say OF 
Picromel, 372 
Picr otoxin, action ‘of, on sw eat secretion, 679 
Pig, bile of, . 370, 373, 376 


193, 197, 199, 201, 
202, 205, 206 
ay euulkquies aie scones -<, 1st 


- hemoglobin of, 


986 


INDEX OF SUBJECTS. 


PAGE 
Pigeon’s milk, . - 675 
Pigments, biliary. See Bile pigments. 
ae of blood, 159, 185 
x: 65 else Ou: urine, 629 
se ,, butter, 20 
is ,, choroid, . 5 : Sent AAT 
5 ,, corpus luteum, : FDO 
ss », of egg yolk, 20 
i + feeces, 388 
a ,», fatty ‘tissues, 20 
a », pathological urine, 628 
9 ” pus, . 84 
a respiratory, 61 
55 of retina, 1G 
ay 5, Serum, 20 
iy ,, skin, 121 
_ 3, Sweat, 673 
Ay) ;, tumours, 121 
x ;> urine, 388, 571, 572, 591, 
616, 628 
Pilocarpine, action of, on intestinal 
secretion, 555, 
557 
a 5 ;, milk secre- 
tion, 664 


s, pancreatic 
secretion, 548 


35 a », salivary 
secretion, 
481, 492, 493, 
498, 500, 
508, 513 
5: ae », Sweat secre- 
tion, 679 
5 2 » uric acid 
excretion, 595 
Pine-apple, proteolytic ferment of, 54 
Piotrowski’s reaction, . 48 
Piperidine, . : 34, 92 
Pituitary body, excision n of, . 945 
55 5, influence of, on ‘meta- 
bolism, : 945 
ag extract, 946 
Placenta, blood of, 733 
36 glycogen of, 918 
Plants, synthesis in, 892 
xs temperature of, 849 
Plasma of blood. See Blood plasma. 
Sees) uaulike 125 
>>», muscle, 95, 96 
Plasmahaut, . 276 
Plasmine, . 164 
Plasmodium of Athalium septicum, HEOiSQ 
Plasmolysis, - 270, 277 
Plastin, ; 66 
Platelets, blood, 141, 156 
Plattner’s crystallised bile, 373 
Pneumonometer, 749 
Poikilothermic animals, 788 
Point, achromic, . 322 
as optimum, : 320 
Poisons, proteid, . 55 
Polycythemia, 143 
Polysaccharides, its 12 
Pore diffusion, . ova 
Portal vein, blood of, : 900, 908, 917 
Potash, : HE tM 
Potassium, 3 : : 2 
5 ‘chloride, PANO hil OE UG 
i phosphate, 76, 78, 82, 87, 108 


PAGE 

Potassium salts in body, . : a 

5,  proteids, . . 25 

5 rp urine, 633, 634 

“ sulphate, 176; 78, 113, Tod 

Precipitants of proteids, chemical, >» on 

mechanical, . 43 

Preglobin, : : 3 eo "368 

Pressure, atmospheric, influence O82 0738 
-. blood. See Blood pressure. 

+ hydrostatic, . 4 : : #280 

is lymphatic, . 299 

ee osmotic, 265, 308, 650 

<5 Hs of cells, . ; 7276 

35 secretory, of bile, . ‘i . 560 

re a ;, saliva, ~) 511,525 

5 a >» urine, é . 649 

Propalanine, - : : : cya 

Propepsine, . 554 

Propeptones, - 405 

Propionic acid, 19, 34, 615, 672 

Protagon, . . 82, ‘lis, 118, 156 

Protalbumose, 410, 412, 414, 416, 418 

se of cerebro-spinal fluid, 184 

Protamine, . < : : 93 

Proteid or ’Proteids, - . 1, 2, 24 

», absorption of, 431, 436, 437, 900 

y i 55 by blood vessels, 309 

a 55 pepsin by, . - 404 

A action of alcohol on, d el 

5 5 - bacteria on, 29, 464, 465 

35 BS pepsin on, . 326, 418 


proteolytic enzymeson, 326 


36 yy superheated steam on, 403 
39 4 trypsin on, 326, 415, 418 
»> animal, 49 


5» Of aqueous humour, . 122, 182, 183 
5, aromatic decomposition products 

of, 5 - 46, 467, 468 
yo SAO ee of urea from, 33 
x », Sugarfrom, 30 
- ie ashi Gk j ‘ 4 : Zo 


;,  assimilable, 437 
;, assimilation of, ; 38, 899 
;, bacterial digestion of, 29, 464, 465 
,, of blood, . : : . 153 
3° 99 9). a plasma; 3) 2538; 061 
i +. bones : : ¥ Pei Bilal 
,, carbohydrate from, . 64 
;, carbon of, : 873 
59 NRO cerebro- spinal fluid, 184 


spt | hy (ehylett : : : 
» | circnlatma ee F . 896, 898 
;, Classification of, 49 
5, cleavage of, by acids, 

,,  coagulable, of digestion, 
5, coagulated, 


406 


> os vegetable, . He pol 
,, colour reactions of, , 


»» composition of, 25 
5, compound, : : x 49, 61 
36 ae digestion of, 428 
;, constitution of, “ 38, 64 
5,  erystallisation of, 43 
,, decomposition of, 5 » 26 
5 B; 3, by acids, Ree 
‘ * sean alkalies, 29 
x as ;, bacterial, . 466 
¥ 5 ,, putrefactive,. 465 
sis 5s 5, in vitro, be ert) 
5, dialysis of, : 43 


INDEX OF SUBJECTS. 


PAGE 

Proteid or Proteids, diet, . ‘ sol 
in diet, 872, 875, 878, 888 
digestibility of, 333, 338 
digestion of, . ; « 399 

», nature of, . 400, 405 


dry distillation Ole. ; a) Be! 


empirical formula of, : Ai 
of epithelium, F - om Oe 
py loury.t. : v1 goo 
formation of fats from, 902, 933 
“e »» glycogen ‘from, 9015 
905, 919 
of gastric juice, : : . 350 
glucoside theory of, . : . 64 
heat coagulation of, . : wed? 
>» value of, . 837, 874, 875 
hydrolysis of, 31, 64, 400 
- by snake venom, 57 
indiffusibility OLN : 24a 45 
influence of, on bile secretion, . 566 
of kidney, : . : 5 be 
pamlens) . «. : yenl23 
living and non-livi ing. (See also 
Bioplasm.) . 38, 80 
of liver, . . - : 85 
» lymph, 182, 286 
Fi lymphatic glands, ; ae OL 
spumeat,| . F i a Ps 
metabolism of, 3 SHV 
of milk, 126, 128, 129, 134, 665 
molecular weight of, : 26, 27 
of muscle, 24, 95, 96, 97 
;, nervous tissues, WG t7 
nitrogen of, . : 5 - 873 
non-assimilable, ; : . 437 
organised, 897, 898 
oxidation of, . ; : preg 
of pancreas, . ; 6 
5» pancreatic juice, . 24, 367, 368 
peptic digestion of, 401, 405, 406, 
414, 541 
of peptic digestion, . . . 402 
percentage of, in tissues, . - 24 
of pericardial fluid, . : . 183 
3 plasma, ; 153, 161 
poisons, . : : OD 
precipitation of, : 40, 41 
by bile, . - 392 
salts, . ax “41 
production of alkaloids from, . 58 
properties and reactions of, . 39 
of protoplasm, . - : = Ol 
of pus cells, . 83 
putrefaction of. (See also Putre- 
Faction. ) . 465 
quantitative estimation of, an P41 
quotient, . . : . 162, 182 
rational formula ofs 27, 34 
of red corpuscles, . : cn ollie: 
;, red marrow cells, . < Br exe! 
reducing power of, 38, 49 
of retina, : ; : bie a Ea! 
rotatory power of, . ; of AS 
of saliva, . ; 344, 503 
separation of, from solution, Bete 4)) 
solubilities of, 39, 50 
of spleen, : ; 87 
», succus entericus, . 368, 369, 557 
;, suprarenal body, . : Sao 


sulphocyanate from, : . 346 


987 


PAGE 

Proteid or Proteids, of sweat, ; . 673 
,, of synovia, F F 5 . 184 
», synthesis of, 35, 893, 899 
5p me in vegetables, 25, 892 
5) + Of testis <7 F : 93 
,, theories "of constitution of, 38, 64 
,, of thyroid, : ; 88, 89 
Pk DISSULG,, re - . 897, 898 
i transudation of, 311 
es tryptic digestion of, 405, 406, 414, 416 
», unorganised, . 897, 898 
»,  ureide theory of, : : 36 
pone OLurine: E : 85, 603 
. 3 tests for, . } - 605 
», vegetable, BAO pilatbe 
a 53 crystalline, 2127, 43, 52 


digestibility of, 


3) 2? 


51, 333, 
441 


,, of vitreous humour, . : 5 aly? 
», of whey, . 2 ; : 5 JIBS: 
Protéide,  . : : é : . 428 
Protein, : : : ’ 29 
Proteinchromogen, 29, 428 
Proteolysis, - : . : 5 8d) 
a estimation of, . : . 323 
Proteolytic ferments, 3138, 319, 326, 334, 
551, 674 


activity of, . - 828 


2) 2) 


a3 3 vegetable, 51, 54, 330, 

403 

Proteoses. (See also Albumose.) . 50 
Bf in blood, : : : . 165 

i 5, cells, 82, 83 


3 cerebro-spinal fluid, f . 184 
i. diffusibility of, . : . 45 


cf in digestion, ; : . 405 

3 from fibrin solution, . 5 ile 

i in muscles, . : f OF 

- as poisons, : 55, 56 

35 precipitants of, . : 214g 

. in proteid decomposition, 28, 32 

3 rotatory power of, : ee erdG 

5 in spermatozoa, . " frega 

in spleen, . : : ma SS 

- synthesis of, . 5 38 
vegetable, : 61, 68, 54 
Prothrombin, 160, 166, 175, 179 
Protic acid, . ‘ : : . 103 
Protoelastose, : . 72, 430 
Protogelatose, : at, 429 
Protoplasm, chemical nature off sO 
% proteids of, : c SPR SL 

35 of pus cells, : ; 83 
reducing power of, . Se eKS. 
Protoproteose, diffusibility of, 45, 46 
ne molecular w eight Of, 9s 9.20 
Pseudechis, venom of, . : 5 58, 174 
Pseudo-cerebrin, . ; : : aerl20 
5,  teeding, - ; : : ooo 

Pe fibrins ; 5 : A . 164 

», hemoglobin, . : : . 237 


: . 63, 456 
7 65, 66, 67, 186 
from phosphogluco- es 


>, mucin, 
»,  nuclein, 


99 99 


teid, : : 64 

peptone, . . . : a Oo 

é xanthine, ; : : 7 LoL 
Psychical feeding, . : » 539, 541 
Ptomaines, . : 5 ; 58, 465 


Ptyalin, 326, 327, 344, 393 


988 


PAGE 
Ptyalin, action of, on amyloses, 326, 394 
an in animals, : By | 
a effect of acids on, . 329 
3 3 reaction on, 329 
55 os temperature on, 327 
>, reactions of, . 328 
Ee separation of, . 327, 328 
Ptyalose, : - . 394 
Puncture diabetes, ; 926 
Purple cruorin, 229 
Purpurate of ammonium, 592 
Purpurin, 623 
Pus-cells, cer ebrosides of, 120 
59 chemical composition of, 83 
E nuclein of, 65, 83 
Bi proteids of, 83 
Putrefaction, ar omatic produe ts of, 46, 467, 468 
5 fatty products of, 470 
Af of proteids, 465 
- tyrosine derivatives of, 467 
Putrescine, 59, 60 
Pycnometer, . 144 
Pyloric g clands, 532, 534, 536 
> . Tegion ‘of stomach, . 534 
ee secretion, 532, 534, 544 
Pylorus, nerve-centres of, siDes 
Pyocyanin, 84 
Pyogenin, 120 
Pyosin, 120 
Pyoxanthin, 84 
Pyrenin, 66 
Pyridine, : 5 : 34 
Pyrocatechin, . 63, 92, 184, 606, 607 
Pyroglutaminie acid, : - =) aD 
Pyrotartaric acid, . 673 
Pyrrol, 431, 34, 35 
QUADRIURATES, 588, 589, 590 
(Quinoidine, animal, 2 109 
Quotient, proteid, «- 162; 182 
re respiratory, . 700, 719, 756 
RABBIT, albino, 37, 173 
- hemoglobin of, . 193 
ae nai: of, . : 131 
>» parotid gland of, : 476 
s, respiratory exchange of, . 706 
Radiation in heat regulation, 850 
Raffinose, : sudil2 
Rat, hemoglobin of, 193, 194, 206 
Receptaculum chyli, 285 
Rectum, absorption by, : . 436 
a temperature of, 787, 788, 824 
Reduced hematin. See Hamochromogen. 

3 hemoglobin, . : ay kot] 
ia 4; crystallisation of, 232 
: En decomposition of, 243 
: . derivatives of, 243 
es a dichroism of, 233 
3 aS production of, 230 

- a quantitative de- 
termination of, 234 
og 7 reactions of, 236 

3 <5 spectro - photome- 


tric constants of, 234 


spectrum of, 


234, 236 
Reducing power, : : 3 (eal 
3 ,, of dextrose, hg 
53 >> 5, disaccharides, LOS ae 


INDEX OF SUBJECTS. 


PAGE 

Reducing power of galactose, sl ele 
33 a2 Vas laciosesse + pat 
sf 59> «=> Leymilosed = eel 
35 35> «39 Maltose; 11, 12 
6 +> 3, Monosaccharides, 7 
a ;, proteids, 8, 49 
53 substance of aqueous humour, 122 
5 oF ;, blood, 152, 925 
a » A contracting muscle,110 
ys os >> Mamma, » 124 
as a >, protagon, . 119 


», suprarenal body, 91 
Reflex inhibition of salivary secretion, . 512 
,, | Stimulation of salivar y glands, 489 
Reindeer, milk of, F 130 
Renal arter ‘ye ligature of, 646 
55 | Svein, ligature of, : . 647 
Rennet, : ‘ 134, 334, 335 
:, action of, on milk, 126, 134 
BS 53 }; pancreatic casein, 138 
5, zymogen, . ; 4 . 543 
Rennin 2 134, 326, 334, 350 
A action of, on caseinogen, - 326 
% effect of acids and alkalis on, 335 
35 », temperature on, . 335 
5 formation of, 543 
reactions of, 335 
“3 separation of, from pepsin, 335 
Reptiles, hemoglobin of, 187 
3 respiration of, : 753 
4 uric acid in muscles of, . <i pL Ol 
3 urine of, 78, 637 
Resch’s test for hy drochloric ‘acid, - 3865 
Reserve air, : F 749, 753 
Résidu fixe, : . 31 
Residual air, : 749, 753 
Residue, albuminous, of hemoglobin, 243, 244 
Resin of bile, $ 2 Sy? 
Respiration in alimentary canal, eis) 
2. apparatus, 694, 695, 696, 697 
: of carbonic acid, 739, 742 
: ae 5 oxide, - 740 
. changes in air during, 754, 756 
“ chemistry of, - 692 
- of compressed air, s yRiOU. 
: cutaneous, . s 128, 725 
iy effect of, on blood, » . 756 
; external, 692 
=p of foetus, . 730, 733 
Pe », fishes, . ‘ 699, 704, 730 
55 frequency of, 747, 753, 854 
1 of gases, s feo 
$5 during hibernation, « , 004 
re of hydrogen, ‘ 739 
se influence of, on bile secretion, 567 
a3 $, ,, lymph flow, 300 
5 internal, : 5 692, 789 
Y of nitrogen, « ed 
3 » Oxygen, . 735, 742 
re >> Vitiated ‘alta 3 aga 
rn volume of, . ‘ : - £48 
Respiratory exchange in air, - 694 
oe causes of, 773, 783 

. of cold - blooded 
animals, 701, 709 

af conditions affect- 3 

ing,. 700, 709, 756 

53 cutaneous. See 

Cutaneous re- 


spiration. 


— ist r= 


INDEX OF SUBJECTS. 


PAGE 
Respiratory exchange, diffusion in, 779 
a in eggs, SVM iRy! 
a5 in fcetus, 733, 745 
+: influence of activity 
of ali- 
mentary 
canalon,719 
Pe . ageon, 722 
BS 3 body size 
on, 720, 745 
i - food on, 717, 
721, 727 
35 st muscular 
activity 
on, 714, 
721, 727 
3 i tem pera- 
tare on, 701, 
709, 727, 
735, 746, 
748 
= me time of 
day on, 721 
43 as measure of heat 
production, 847 
3 measurement of, 
694, 754 
55 tables of. See Tables. 
5 in tissues,. 780, 840, 
895 
e of warm-blooded 
animals, 709, 711 


35 in water, 
Respiratory oxygen, 


699 


185, 235, 236 


93 pigments, . 5 il 

By quotient, 700, 719, 756 
Reticulin, ‘ : : 70, 72, 88 
sy decomposition of, 0032 
Retina, : : 121 
Retinal cones; — + - 20 
Retrolingual salivar y gland, . 476 
Reversion, : ; 10 
Rhamnose, 2 
Rhodopsin, . 122 
Ricin, : 55 
Rickets, 886 
Rigor mortis, 95597 
Rotation, specific, é 6 
Rotatory power of chitosan, 75 
eg 33 cholesterin, 23 

Es ,, dextrins, . 5 elle 

Fe % disaccharides, MOP, 

Ap », gelatin, wel 

”? ”? glycogen, 15 

ae ,, glycuronie acid, 5 

o ;, 1mulin, ; 14 

ms ,;, leucine, 28 

a4 », proteids, . 46 
starch, : 14 

Ruminants, salivar ny secretion of, . 489 
Rye, proteids of, 54 
SaccHaRic acid 4, 5, 34 
Saccharo-lactonic acid, 5 
Salamander, respiration of, 725 
Saliva, 2 ‘ : 4 342, 501 
;, abnormal constituents of, 504 

;, action of, on starch, 393 

;, amount of, 491 


» of animals, 3 a : 


989 

PAGE 

Saliva, antilytic secretion of, 522 
;,  antiparalytic secretion of, - 522 
,, augmented secretion of, 497, 525 

,, ¢Chorda, 3843, 496, 497, 498, 500, 506, 


507, 511 

composition of, effect of rate of se- 
cretion on, 

», stimula- 


499 


9 LB) 


tion on,. 498 
dyspneeic secretion of, 493, 521, 522 
gases of, 346, 347, 504 
influence of blood variations on, 508 
mixed, 344, 348 


organic constituents of, 344, 347, 494, 
496, 498, 500, 507 


paralytic secretion of, «+ 519 
parotid, 527, 343, 346, 347, 494, 495 
percentage of fat i ees ff 
pilocarpine, 481, ‘492, 193, 498, 500, 

508 
proteids of, 503 
reflex secretion of, 489 
spheres of, ; - . 502 
sublingual, 343, 347, 494, 495 
submaxillary, 327, 342, 346, 347, 494, 

495 
sulphocyanate of, 342, 343, 344, 345, 

504 


sympathetic, 343, 494, 498, 500, 506, 


507, 511, 525 


,, tables of analysis of, . 347, 348 
tension of gases of, . 784 
Salivar y concer etions, c . 345 
:; corpuscles, 344, 501, 663 
> enzyme, . 326, 327, 397, 503 
;, ferment. See Hnzymes. 
», glands, . : i : ATS 
i ,, action ofalkaloidson, 512 
os » admaxillary, 476, 479 
Ph ;,  albumino-mucous, 478 
7 ;,  albuminous, a Ah 
- ie alveolar cells of, . 477, 485 
e4 », alveoli of, 477, 507 
5 », anatomical characters 
Oise e ; 475 
FF », Of animals, . 47S 
a ce blood flow of, 504, 505 
iY, » changes in, during 
secretion, . 485 
a wd chemistry of, 92 
i ;,  demilune, 478 
6 7 auctsiof, 477 
* “if electrical changes of, 517 
ie >, extirpation of, 524, 930 
Be oH heat-production in, 516, 843 
3 », histological characters 
OE 477 
3 a5 influence of cortical sti- 
mulation 
on, 484 
ss Bs medulla on, 484 
ss i irritability of cells of, . 524 
6 ,, lymph flow of, - 510 
> a mixed, : 477 
5 > muco- -albuminous, 478 
As A mucous, 477 
5 | Seenves of, cranial, 479, 482, 
504, 52: 518 
as 3 sympathetic, 479, 


"” 483, 504, 518, 522, 526 


99° 
PAGE 
Salivary glands, nerve-ganglia of, 480, 482, 
484, 523 


S53) | pOLDItal; 476, 478 
secreto-inhibitory fibres 


iy - 526 

. 3 secretory fibres of, . 526 
- 4 AD pressure of, 511, 
525 


section of nerves of, . 519 
stimulation of cranial 


nerves 

of, 493, 505, 

506 

39 99 99 9 reflex, 489 
> ” »» Sympa- 

thetic nerves of, 494, 505, 

506 

Ba = trophic fibres of,. 526, 528 

+ 5 weight of, . : 7) AdG 

;, secretion, antilytic, . 2 - 522 

a latent period of, 494, 505 

” 5 osmosis in, : - 929 

- a paralytic, . : Sly, 


reflex inhibition of, . 512 
through _ peri- 
pheral ganglia, 523 


be) 9) 99 


p in ruminants, . . 489 
Sallkcow ski’s reaction, . 5 : 428 
Salmine, ) . gue 


Salts. See Inorganic constit vents, 

Saponification, . : - a9) 446 
Saprine, : x CY 
Sarcolactic acid of aqueous humour, env 22 
blood plasma,. 157, 159 
liver, OO 


- e muscle, 95, 99, 104, 106, 
110, 911 
- », Spleen, . : i, 0S 
3 », thymus, . . 7 38 
55 », thyroid, . : aa, . 88 
saunines mils = O16 
Sarcolemma, chemical nature of, a )s9 
Sarcoma, melanotic, iron in, - 5 athe: 
Sarcosin, . : : ‘ - sh yh Bhi 
Sarkin, : . 596 
Sauropsida, urinar ry excretion of, . . 637 
Sausages, alkaloids in, 4 : «4,409 
Scherer’s Gest, ti : a . 423, 424 
Schizoneura lagunisosa, : . eG 
Schlieren-apparat, - 269 
Schloésing’s method of estimating am- 
monia, . 3 5 - 5 BE 
Schultze’ s Glaskir. “per, . : : sity @ BIE 
Schweitzer’s reagent . ‘ - stag 116 
Selerotic, . - : : - s. gg ill Zi 
Scyllite, . : : : - SH 
Sebaceous glands, ; : : . 674 
3 secr etion, : : : . 674 
53 a influence of nerves 
Gy  s - 5 eel 
Sebum, é 5 4 ‘ . Ea Gs4: 
Second wind, 5 : : : aS LY 
Secretion of bile. See Bile secretion. 
Secretion, digestive, . : ‘ . 842 
3 gastric. (See also Gastric 
secretion. ) - : PCE) 
a internal, . 3 ‘ 5 BY 
> intestinal. See Intestinal 


secretion. 
milk. See Jfilk secretion. 


INDEX OF SUBJECTS. 


PAGE 


Secretion, mucous, of mouth, 344, 348 


As pancreatic. See Pancreatic 
secretion. 

56 salivary. See Saliva, Salivary 
secretion. 

33 skin. See Skin secretion. 

AE urinary. See Urinary secre- 
tion. 


Secreto-inhibitory nerves of pancreas, 549, 550 
salivary 
glands, . 526 


39 99 


Secreto-motor nerves of kidney, . . 660 
Secretory granules, gastric, . . . 531 
3 >> intestinal, : . 554 
ae », Mammary, . . 668 
a >> pancreatic, ; . 546 
a ,, Salivary, : ~» 479 
si nerves, : « 526 
ae _ of kidney, . : . 660 


», orbital gland, . 482 
>» pancreas, 549, 550 
,», salivary glands, 479, 482, 

493, 494, 512, 525, 526 


39 39 


9? ”? 


9? 3? 


se pressure of bile, . : 5 Stay) 

3 - saliva, . 511, 525 

Selachians, urea in organs of, - - 103 
Semen, chemistry 0) a : : aoo 
Semicollin, : - - 71, 430 
Semiglutin, . : 71, 430 
Semilunar ganglion, . : : . 550 
Seminose, . : : - 7 
Semipermeable membranes, . . 264 
Sepia, skeletin of, - : - =: ee 
Sepsine, - : : shy dy 
Septic fluids, alkaloid of, : : a 
Septicine, . ae : . Do 
Sericin, : 5 74, 76 
Serine, ; 5 : ‘ . . 163 
Serous fluids, : : - wets 


161, 163, 182 
of aqueous humour, . 122 
carbohydrate from, . 64 
carbonic acid in, . rel 
coagulation temperature 
Oleg. : : . 43 


Serum albumin, 


is x3 crystallisation of, aes 
a ae heat value of, . . 834 
- - mechanical _ precipita- 

tion of, . : aig, 
i 3 rotatory power of, «246 
Be ash of, : : ee 2, 
- bilirubin in, . . . . 383 
oe fibrinogen, 3 ; . weiss 
ne gases of, . ‘ : Lad, 


» globulin, . 161, 163, 182 
of aqueous humour, ee i? 
carbohydrate from, ce at 
mechanical precipita- 


tion of, 

i: 5 rotatory power of, . 46 

sa . temperatureofeoagula- 
tion of, . . 43 
e lutein, : : 20, 159 
ah of muscle, : : - adpéQ6 
pigment of, 20, 159 
Shark, bile of, . : : . 373 
Sheep, hemoglobin of, . : - 193 
* )milkof ae. : . 130 
BS salivary glands of, ~ Ata 
Shell-fish, alkaloids in, «= jp 


INDEX OF SUBJECTS. 


PAGE 
_ Silica, . : : ; 25, 79, 473 
Silicie acid, . : ‘ : asi 
rf in liver, . F : Os, 
EA », urine, 634 
Silicon, E 2 
Silk, skeletin of, 76 
Silkworm, skin of, 16 
Sinistrin, . ali f 64 
Skatol, 29, 47, 72, 467, 468, 469, 473, 607 
;, excretion a 470 
», tests for, : . 469 
Skatol-carbonic acid, 29, 47, 467, 468 
aS », tests for, . 469 
Skatoxy]l, : . 470, 607, 628 
is glycuronic acid, . - 613 
a5 red, : 628 
2 sulphuri ic acid, 631 
Skeletal tissues, chemistry of, Eilat 
Skeletins, : 70, hs (4,15; 16 
Skin, absorption by, in animals, 688, 690 
as  1nman, 669, 685 

33 glands, electrical ‘phenomena 
Of = : ; ; : 20a 
;, loss of heat from, 850, 855 
;, respiration by, - 423, 425 

», secretions. (See also Sweat, 
Sebaceous secretion.). 669 
Pn as alkaloid in, : 673 
Je Ds chemical nature of, 670 
be x functions of, 669 
- 33 nervous mechanism of, 676 
sa - of vertebrates, 669, 673 
a watery, 670 
33 temperature of, 829 
», varnishing, . VE 
Slime of fishes, 674, 676 
Smegma preputii, 674 
Snail, gluco-proteids of, 62, 64 
;, skeletins of, 75 
Snakes, temperature of, 849 
2 urine of, . 590, 909 


;; Venom of, 55, 56, 181 


* a3 action of, 57, 146, 174, 179 


A 55 toxic power of, . 5 EE 
Soaps, . - : 19, 20, 446 
», absorption of, 451, 456, ‘457, 463 
;, nutritive value of, Bp etoul 
Soda, . , : : j VlegSd 
Sodium, , : : . : : 2 
a bicarbonate, 5 ls 
carbonate, . .76, 78, 145, 157 
_ chloride, 25, 76, ai 93, 113, 154, 
157, 882, 883 

Bs os precipitation of pro- 


teids by, 42 


»» phosphate, . 76, 78, 113, 145, 157 


ye salts of body, . 77 
- ;»  proteids, 25 
;> urine, 633, 634 
sulphate, 76, 78, 113 
Soluble ferments. (See also "Enzymes. )» 812 
;, Starch, : : 13, 14, 395 
Sorbite, : - . - 4 
Soret’s band, 226, 227, 246 
Specific gravity of blood, 143 
3, heat of body, 838 

», rotation. Sea also Rotatory y 
power.) . ; 6 
eee hotometer of Hiifner, 220 
a eV, ierordt, 216 


991 
| PAGE 
| Spectrophotometric constants of CO-he- 

m 0 g- 
lobin, 239 
”? >, 0 xyhe- 
mo g- 
lo bin, 
| 213, 223 
55 ve. ;, reduced 
hemo- 
globin, 234 
_ Spectrophotometry, 209, 216, 313 
| Spectrum of bile, . . 390 
- +> ») pigments, "383, 386, 387, 
388 
a ,, CO-hemoglobin, 239 
x ;, bematin, + 2D 
‘5 ;, hematoporphyrin, 260, 382, 
626 
= ,, hemochromogen, . 251, 255 
2 ;, HCN-hemoglobin, 248 
5 ;, methemoglobin, 246 
- ,, NO-hemoglobin, . 241 
a ,, oxyhemoglobin, 208, 211 
33 in Pettenkofer’s test, sn SAT 
3 photographic, . - 225, 236 
3 ;, Of CO-hemoglobin, 240 
_ » » Oxyhemo- 
globin, 225 
5 of reduced hemoglobin, 234, 236 
+5 ,», retinal pigments, 123 
” 29 urine, ° 617 
= 3, urobilin, 621 
A ,, uroerythrin, . 625 
visible, 208, 234 
Spermaceti, ; - 20 
Spermatozoa, composition of, 93 
nuclein of 65, 66 
Spermine, phosphate of, 94 
Spheres, salivary, - 4 . 502 
Spider, poison of, 55 
Be me ey secretion of, 637 
»> web: of == ; 76 
Spinal cord, percentage of proteids in, 24 
Spirographidin, ra ; gt 0% 
| Spirographin, . 64 
Spirographis, hyalogen of, 64 
Spirometer, . 752 


Splanchnic nerves, ‘influence of, on gastric 
secretion, . . : - 939 


Spleen, chemistry of, 87 
;, during inanition, - 990 

», influence of, on metabolism, - 959 
Sponge, skeletin of, . : - =e 
Spongin, - 74, 75, 76 
Sputum mucin, . 62 
Squirrel, hemoglobin of, 193, 195, 198, 
204, 206 

Starch, . : : - Asis; 14, 473 
», absorption of, . - . 484, 485 

;, action of ferments on, .326, 393, 394 

s 53. pacidsionye: - - 396 

;; assimilation of, - - 880 

;, bacterial digestion of, : - 470 

;, cellulose, A a pple 

ms digestion of, 393, 396, 556 

»,  granulose, - : =a! 

», heat value of, . 834, 835, 837 

», hydrolysis of, 13, 14, 396 

55. paste, : a pele 

», soluble, 13, 14, 895 


992 INDEX OF SUBJECTS. 


PAGE 
Starvation. See Jnanition. 
Steapsin, 326, 336, 339 
Stearate of magnesium, es 
Stearic acid, 18, 20, 22, 118, 119, 
456, 675 
Stearin, 18, 133, 159 
Stearyl, : : is} 22 
Steatolytic ferments. See Ferments. 
Stercobilin, 388, 474, 622 
Stethal, : : : : F > 20 
Stoffwechsel, - : : : . 868 
Stokes’s reagent, . ‘ : ; . 230 
Stomach, absorption by, : : = Heh) 
+6 changes in, during digestion, 531 
- fundus of, . : . 534, 544 
Mg gases of, , ‘ ; see 20 
a5 nerves of, —. ; : 5 Be 
no nerve-centres of, . . 2) 5388 
he ,, _ plexuses of, . - = OOS 
pyloric region of, . . 534, 544 
Stroma of corpuscles, : : J ilsksy ge) 
Strychnia, action of, on sweat secre- 
tion, - : : : : q OY 
Sturine, : : : : ies 29D 
Sublingual ganglion, E : . 480, 481 
46 gland in animals, e475; 478 
oP 5, herves of, . 479, 483 
saliva, 343, 347, 494, 495 
Submaxillary ¢ canglion, 480, 481 
NS cland in animals, : eas 
- », heat production i in, 516, 
843 
~ »> nerves of, 479, 483 
et mucin, . me AG2 
is saliva, 327, 342, 346, 347, 494, 
495 


104, 465, 470, 673 
(See also Intestinal 


Succinic acid, 
Suceus entericus. 


secretion. ) : 368, 397, 398 
A ae enzymes of, 341, 397, 398, 
556 
5 m; mechanism of secretion 
of, . : : . 554 
a proteids of, : nia 
Sudorie acid, : 671 
Sugar. (See also Monosaccharides, Di- 
saccharides.) . e = : MOD 
», absorption of, . . 435 
, bacterial digestion of, : 470 


6, 10, 158, 610, 894, 914, 
916, 917, 920, 923, 


. in blood, 


925, 926, 928 
Peecane: ; 3 2,454,693 10, 398, 435 
Fle chyle, : : . 183 
;, in digestion of alycogen, 5 . 397 
43 ss ,, starch, “ Pee ho) 
Ks heat value D5 oc : : eed: 
© bof liver, : 85, 926 
. ee lymph, s- : : : a coy” 
ie in metabolism, . E ~ 4922 
vee <5, ailike (See Lactose. ) 9, 12 


” muscle, 100, 105, 110, 606 
production of, from proteids, - 450 


5) «Synthesis’of,, - .. : - : 5 
,, of tendon mucin, - , 62 

», of urine. (See ‘also ‘Glycosuria, 
Lactosuria.) .. : . 608, 612 
Sulphates, calcic, ; 5 us 
uf potassic, 76, 78, 113, 157 


sodic, 76, 78, 118 


PAGE 
Sulphates of body, 26, 79 
5 5, Sweat, . . 672, 673 
,, urine, > 265 79 , 613, 631, 906 
Sulphide of iron, . 78 
Sulphocyanate of proteid metabolism, 346 
a »» Saliva, , 343, 344, 345, 
504, 632 
Sulpho-methemoglobin, . : 249 
Sulphur, . : : : ; ‘ 2 
,, of amyloid substance, . me ve 
- ss niles. : : 4 7 901 
;, elimination of, ¥ s weeny 5 
5) ofsfood ae : : 2 . 563 
¥ ,, hemoglobin, $ 3 £01202 
boo * 95) Keratins Wane : A +13 
a ;, liver cells, . : ¥ SueOD 
¥ ;; proteids, 26, 29 
x ,, taurine, : ’ 3 2 1379 
>> urine; . - 630, 631 
Sulphuretted hydrogen, 29, 32, 72, 73, 76, 
470, 4738 
ay ue of alimentary canal, 
729 
Sulphuric acid, 25, 26, 30, 77, 87, 630 
Supplemental air, 749, 753 


Suprarenal body, chemistry of, : - 90 
of Elasmobranchs, soagoT 
excision of, 4 . 948 


9? 29 


oh) 29 

3 5 extractof, 950, 9515 967 

5 ;, influence of, on meta- 
bolism, . - 948, 958 
a of Teleostei,  . . 957 
Sweat. (See also Skin secretions. ) . 670 
», of animals, : , : . 673 
3 carbonic acid of, ‘ é > 671 
», centres, . . 679 
a chemical composition ‘of, 5 Git 
» creatinine of, . , . 672 
;, ethereal sulphates ofu . 672, 673 
» fatty acids of, . : . 672, 673 
‘5 nitrogen-excretion by, - » 672 
», percentage of fat in, . - 4 agli? 
5,  proteids of, 673 


,, secretion, action of alkaloids on, 679 
ie temperature 


bi] 929 32 


on, . - 680 
ro 9 mechanism of, . = 676 
ay nervous influence on, . 676 


671, 672, 673 
671, 672, 673 


be) 
55 wsalltsso# 
5» urea of, 


Swimmin g-bladder, 3 704 
Sympathetic nerves of salivary glands, 497, 
483, 504 
” 2 2 9 section 
of, =) 522 
” ”? cB) bE stimu- 
lation of, 494, 505, 506, 
508, 526 
e saliva, 343, 494, 498, 506, 507, 
51d. 6200 
Synovia, . : 181, 184 
a percentage of fat i in, Jt% owl aadlet 
= 4 PE oteid i i Pe: 
Synthesis of alkaloids, : 2 68 
ne ,, choline, . F 21 
be wetats: 893, 899, 931 
- ,, glycocoll, ; 379 
3h ;, glycogen, : . 893 
a ;, hippuric acid, . 600, 892 
5 ;, leucine, . : ‘ . 421 


INDEX OF SUBJECTS. 


PAGE 
Synthesis of organic substances by ani- 
mals, 892 


” » 39 », plants, 


25, 892 

sf 5, proteids, 35, 893, 899 

* » sugars, , 5, 6 

sf ,», taurine, 379 

aA >, urea, . 581, 893 

et ULic ‘acid, 586, 893, 909 

Synthesised colloids, . ens6 

Syntonin. (See also Acid albumin. 505 an: 
AP rotatory power of, S A 


TABLE of analysis of bile, 370, 371, 568 
Oke 


oB ” ” ry elastin, 
” ” % 9 keratin, 73 
ay) pea, lymph; 182 
” ” sf ;, mucins, 62 
Dy Aa 55 9, Oxyhemoglobin, 198 
” ” » om) pancreatic juice, 367 
Swen »> 3, Placental blood, 733 
” ” ” > saliva, 347, 348, 496, 
498, 499, 500, 508 
Jp AEE skeletins, : : 
Pes, ash ‘of milk, . she 
»> >, bile pressures, 560 
+: 35 carbonic acid absorption, 770 
s900" Se » in serum, fii 
Pen, composition of blood, 153, 154 
aa Aa 9 AS colostr um, 127 
Bess a ,, foodstuffs, 874 
ee 30 op >, milk, 128, 129, 130 


ies 5 5, nervous tissues, 116, 


117 
” ” ” ” protagon, 119 
oe) ” oe ” sebum, 674 
on aE 5 », sweat, 671, 673 
ie 5, urine, 572, 573 
sat” are constituents of meat, ee NG) 
»» >) copper, nickel, and cobalt re- 
actions of proteids, . 48 
Pe TCIets: F é 877, 879 
aie diffusions, j : - . 264 
>» >) enzymes, 326 
s> 5) experiments in asphyxia, 743, 744, 
745, 746 
4). aE O ,, respiration of 
carbonic 
oxide, 741 
” ” SE eb oxygen, 737 
Pee fexpired, air : 755 
ee) 4) tiltrations; 282, 283 
»» 5, frequency of respiration, 747, 753 
>> 35 gases of alimentary canal, 729 
Pe, 55, 235 blood, 715, 761, 763, 
764, 769 
»> 5, heat of combustion, 834 


», loss . 850 
production, 833, 838, 847, 853 
hydrolysing processes of ‘fer- 


ments, : Beers 
»> 5) Inorganic constituents ofbody, 77 
ae food, 882 
Aes isodynamiec foodstuffs, 835, 837 
5» 9, leucine and tyrosine, . 425 
»» 5) nitrogen absorption, 769 
55 ae », and sulphur elimina- 
tion, + 1562 


VOL. I1.—63 


Table of nitrogen loss in inanition, 
»» 5, nutritive equilibrium, . 
»» 9) OSMotic pressures, 


»» 9, Oxygen absorption, _ 
»> 9, percentage of chlorides 


O95 


PAGE 
890 
871, 872 


265, 266, 267, 


278 
766, 767 
in 


hody fluids, 77, 78 


” ” ” ” fat in tissues, 17 

sy. 6 3 ,, Iron in hemo- 
clobin, 201 

” ” ” ” phosphorus in 

nucleo - pro- 
teids, . 81 

” ” ” ” proteids in 
tissues, 24 

> » Ap Swaber ion 
muscle, 95 

” ” ” ) ” nervous 
tissues, 115 
»» 9) proteids, 48 
3 Bae gee Of lens; 124 
3 - ns 5, plasma, 162 
eens resiaual ain. 5750 
»> 9, respiratory exchanges, . 701, 706, 
(AO LG 4S AGE 18: 


722, 723, 724, 726, 734, 


795, 841, 848, 


859, 864 


»> 5, rotatory power of proteids, 43 
ee esaltsrofimillk ; 131 
3 Caan iset sweat, : 672 
baoan8 solubilities of albumins and 
globulins, 50 
pees s > casein and 
caseinogen,. 138 
»> 9) Sweat secretion, 671 
»> 5, temperature of ‘blood, ‘ 827 
mate ¥55 55 ss body, 789, 790, 791, 
793, 795, 799, 801, 


805, 806, 808, 809, 
810, 811, 813, 815, 
817, 818, 825, 826, 


860, 867 

Fe eee a », coagulation of 
proteids, 43 

Pe alc A after skin-var- 
nishing, 727 
s> 9) Urea excretion in inanition, 888 
4) 9, Vital capacity, 751, 753 
», weights of salivary glands, 477 
Tail- gland of birds, 675 
Tannin, precipitation 0 of pr oteids by, 40 
Tartar, ; 345 
Tartaric acid, . 5 
Taurine, - 379 
,, in bile, 372, 373, 378, 379, 562, 632, 
901 
>) Kidmey, ‘ n o2 
5 ,, muscle, : : 100, 103 
», from proteids, . ‘ ; 901 
eee Ih Rae body, : 90 
Taurocholic acid, 372, 373, 374, 376, 392, 
454 
,, of suprarenal body, 90 
Teichmann, crystals of, : - 202 
Teleostei, suprarenals of, - 5 SEIU 
er aniasn of axilla, . 787, 788, 824 
be , bees, 5 USP SW 
a i ” birds, 787, 791 
, 5, blood, 826 
,, body, 788 


994 
PAGE 
Temperature of body, determination of, 786, 
792 
a coeflicient of filtration, . 281 
- of cold-blooded animals, 787, 
792, 849, 865 
6 compatible with life, » 821 
53 conditions affecting, 1198 
if constant, development of, 865 
a after death, . : . 866 
oe diurnal variations in, . 198 
a during hibernation, 5 Joe 
5 ee inanitions 889 
A individual peculiar itiesin, 812 
sf influence of age on, . . 803 
3 + ;, baths on, ~ sols 
5s - ,, drugson, . 820 
Fe ee ,, food on, . 809 
a . , heat and cold 
City 5 ule! 
a5 Ae ,, menstruation 
One. 812 
- 33 $5 mental work 
ODS iss 807 
3 55 », Pregnancyon, 812 
a Ae >, race on, Sheol 
Bs m. », seasonon, . 813 
5 5 a SOX ON, eG) 
> 5, Sleep on, > S10 
33 a ,, surrounding 
temperature 
ons ji 5 hl 
ae = ;, Work on, . 806 
r 59 ,, on zymolysis, 320, 
327, 331, 335, 337, 339 
AS internal, . 824, 826 
- of mammals, . : a CEL 
m of mouth, 787, 788, 824 
as of plants, ; : . 849 
Ms of rectum, . 787, 788, 824 
43 regulation. (Seealso Heat.) 831 
& after section of cord, + S06 
55 of skin, . - 5 ey) 
es after skin- varnishing, 5 
5 vasomotor control of, ood: 
35 of warm-blooded animals, 787, 
788, 865 
Tendon mucin, . : ; ? =, (62 
;, section of, effect of on muscle 
glycogen, . ; . 5 os) 
Tension of dissociation, ‘ : be MED 
Testis, chemistry of, . : ‘ 5 
Tetanine, : ; 59, 60 
Tetanus, alkaloid i ith ve : d ea ad) 
Tetra paper, : : i : . 365 
Tetronerythrin, . : : : 3. AD 
Tetroses, . : : ‘ : 7 2 
Tewfikose, . : ae l3 2 
Theory or Theories, cleavage, of proteid 
digestion, 405, 406, 
414, 416 
“i of fat absorption, . 449, 
451, 457 
Re 5, glycogenesis, . 922 
55 hydrolytic, of pep- 
tonisation, . . 400 
ae of metabolism, . 870 
‘s micellar, of peptoni- 
sation, : 400 
a of proteid constitu- 
tion, . : ros 


INDEX OF SUBJECTS. 


PAGE 

Theory or Theories of urinary secre- 
tion, : : : : ; . 639 
Thermometers, . ; : F (ke) 
Thioglycollic acid, : : ; = S26 
Thiolactic acid, . ; j ; » 84 
Thiry fistula, . 3 : . 3868, 555 
x Vellantistulass ee ; : £ F555 
Thoracic duct, . 5 < ; 1 p2o0 
2 », sources of lymph of, - 290 
Thrombin, 160, 166, 170, 75.179 
Thrombosin, : 165, 172 
Thymic acid, ‘ : - ; >, OG 
Thymin, : 66, 93 
Thymus, chemistry of, 5 : cS 
3 function of, . : ; OO 
5a iodinein, . ; ‘ 5) 
Pe nucleic acid of ae P66 
percentage of proteid i in, Da te 24 

ss phosphorus of nucleo- proteid 
Ofer es 5 ; OL 


Thyreo-antitoxin, - 5 >) Bg 
Thyreoproteid, . - . - 5 ey 
Thyroid, ablation of, 


it chemistry of, 

pe extract, C ; - - 943 
ne feeding, i H : . 944 
ss grafting, : am poo 42 
internal secretion of, : . 938 
Thyroiodin, . 3 : ‘ : 5 ey 
Tidal air, : : : . 748, 753 
Tide, alkaline, ; ‘ 579 
Tissue fibrinogens, 53, 68, 173, 176 
3) . proteidis),< : 5 
», tension, . : : sO 7 
Tissues, chemistry of, : : = tei) 
Toad, parotids of, ; : 5 £0674 
», skin secretion of, . ; . 673 
Tollens’ reaction, . : - ‘ 5 oy 
Tomato, pigment of, . : ; co 20 
Tooth, chemistry of, . : i see 2: 
Topler Schlien Karst 2 : P - 1269 
Torpedo mucin, . 3 ; allo 
as organ, . : Z : 6 lt) 
Torula uree, é 5 . 4 . 313 
Toxalbumoses, : 5) 6a 
Toxic power of anthrax albumose, Shy 
a ,, cholera toxo- -peptone, 2 | is 
a ,, diphtheria toxin, . fads) 
e ,», peptone, : 3 LOD 
be ,, snake-venoms, . DS 
Toxins, , : : EY} S) 
Transudation of proteids, : : 5 alge 
Traube cell, : : : = e269 
Trehalose, . ; A ‘ ; “eel 
Triacetin, . 4s eS 
Tribromamido- benzoic acid, . 4 weeo” 
Tricalcium casein, : 5 ae 

Trichloracetic acid as S precipitant of 
proteids, . 2 : - 7.40 


Tr ichlorethylglyeur onic > acid, : . 614 
Trihydr Ome Leayls bat se ‘acid, . 606 
Triolein, . 2 eels 
Trioses, ° : ; : ; 2 
Trioxybutyric acid, : - ; : 5 
Tripalmitin, : ; : : aS 


Tristearin, . : - : ‘ as 
Trommer’s test, . = 7 
Tropeolin test for hydrochloric acid, . 3865 
Trophic nerves, . : 526, 528 


Trypsin, 326, 336, 337, 415, 552 


LS 


INDEX OF SUBJECTS. 


PAGE 

Trypsin, action of, on proteids, 326, 405, 406, 
416 

‘3 Ns », milk, 127 

5 estimation of activity of, 323 

e. influence of reaction on, . 337 

AF ;, temperature on, . BBM) 

35 preparation of, 315 

Pe reactions of, 337 
Trypsinogen, 551 
Tryptic digestion, 414, 418, 428 
+ amido-acids of, 421 

55 ammonia of, 427 

<5 chromogen of, P » A27 

a cleavage theory of, 405, 

406, 416 

organic bases of, 426 


417, 421, 427 
639, 650, 652, 655 


Tryptophan, 
Tubules, renal, 


Tunica media, percentage of proteids in, 24 
Tunicata, test Gite 5 5 5. alts 
Tunicin, 4, 14, 16 
Turacin, 5 al 
Turbellarians, hemoglobin of, 187 
Typhoid fever, alkaloid i in, 59, 60 
Typhotoxin,. 59, 60 
Tyroleucine, 31 
Tyrosine, : - 423 

», absorption of, ; 469 

», in bacterial digestion, 466 

a constitution of, 423 


er from decomposition of albumi- 
noids, 72, 73, 
74, 75, 76 
,, proteids, 28, 
” 99, 31, 32, 34, 46, 63 


9 39 


>, derivatives of putrefaction, ‘467 

AS from different substances, 425 

», im digestion, 405, 406, 416, 421, 
423, 437 

an ;,. liver, 86 

73 »» pancreas, . 92 

»» Separation of, from leucine, 424 

» in spleen, 87 

i >> sweat, 673 

- op testis 93 

= tests for, - = . 424 

in urine, : : ‘ - 602 
Tyrosine- hydantoin, 602 
Tyrotoxicon, 59 
URATE of ammonium, 78 
Pens) calciuin, 78 
Urates, 087, 588, 590, 591 
Urea, - 581 
», amount of, . . 892 

», 1n aqueous humour, = 225 183 

», artificial production of, 33, 427, 581 

» in bile, 390 
See blood, 160, 900, 902, 919 
Bs chemical composition of, 581 

» in chyle, 2 v? 83 

,, decomposition of, 581, 582 

,, estimation of, : . 583 

>, excretion during inanition, . 887, 888 

», ferment, o) 07 

a formation of, in liver, . 906 

», heat value of, 834 
4, hydrolysis of, 582 


Urea, 


9 
39 


2? 


23 
2? 
29 
oe) 
2) 


39 


Ureides, 


Uric acid, 


oi) 


9 


9 


bel 


> 


>> 


9 


995 
PAGE 
in intestinal juice, 557 
,, kidney, ; Mi 2 |. 092 
,, liver, 86, 562, 902 
», lymph, 5 82 
,, metabolism, 906 
», milk, : L2G 
», muscle, 100, 102, 904 
nervous tissues, 4 le 
nitrate of, 581 
oxalate of, 581 
oxidation ‘of, 583 
preparation of, 583 
production of, from arginine, 33 
5 PP », creatine, 904 
3 99 Lysatine, 33 
proper tiesiof, V). 581 
in proteid decomposition, 28, 33, 34, 427 
quantity of, 584 
relation of, to ammonium carbonate, 582 
He ,, uric acid, 586, 593 
in saliva, 344 
salts of, i 5 Bill 
in sweat, 671, 672, 673 
synthesis of, : . 581, 893 
in synthesis of pr oteids, 35 
tests for, : 583 
in tor pedo organ, 3 : 5 ati! 
79) URINE sy A 51, bI2, 58L, 637 
Ureide theory of proteids, : Gan ate 
‘ 586 
Ureter, ligature of, 649 
‘ 586 
in blood plasma, : 160 
chemical constitution of, 586 
condition of, in urine, 588 
effect of diet on production of, 593 
estimation of, > p92 
excretion in disease, . 596 

Pe individual —_varia- 
tions in, 595 
i influence of drugson, 595 

ft baled 575) OXCLCISE 
on, 595 
heat value of, 834 
intestinal excretion ate 595 
in kidney, 92 
,, leucocytosis, 67 
,, leukeemia, ; : = 910 
=) lnyers 85, 86, 902, 909 
;, metabolism, F - 909 
,, muscle, 100, 101 
,, Nervous tissues, 116 
,, new-born children, . 595 
, pancreas, . 92 
pr eparation of, 591 
properties of, . > SY 
from pr oteid decomposition, 28 
quantity of, . - 586 
reactions of, 592 
relation of, to xanthine bases, 67, 
596 
* yy urea, 586, 595 
salts, : - don 
in spleen, . 87 
spontaneous separation of, 578, 588 
in sweat, . 673 
synthesis of, 586, 893, 909 
tests for, 592 
variations in amount of, 5 BRE 
of urine, 571, 572, 586, 637, 653 


996 


Urinary excretion, characteristics of, 


22 


92 


INDEX OF SUBJECTS. 


PAGE 
635 
388, 571, 572 
Bowman’s theory 
of . 639, 650 
55 concentration of, 650 
gs Heidenhain’s theory 
of, * 4%, . 652, 658 
oa influence of circula- 
tion on, 
641, 644 
,», diuretics 
on, . 647 
,, ligature 
of renal 
artery 
on, . 646 
,, ligature 
of renal 
veinon, 647 
,, ligature 
of ureter 
on, . 649 
») nerves 
on, 645, 659 
<3 Ludwig's theory of, 640, 
658 
iS mechanism of, 639, 658 
59 pressure of, . 649 


pigments, 
secretion, 


” bP) 


3 39 


> 3 


9 be] 


theories of, s639 

water, secretion of, 641, 644, 647, 
656 

» 570 

Capetone i in, er, 1928 
acids of, 571, 574: 
albumin of, 604, 605 
albumose in, . 694 


alkaloids in, : é : st 759 
amido-acids of, . 
ammonia of, 
ammonium salts in, 


906, 908, 
animal gum of, : . 


aromatic car boxyacids i in, - 606 

a3 constituents of, 605, 631 
bases of, . 5 é : Be ay/fil 
bile pigments in, 384, 629 
blood pigments in, . 629 
calcium salts of, 634 


cane-sugar in, . ; 3 lO 


carbohydrates of, aq) 1607 
carbolic acid in, 606, 607 
carbonic acid of, 634 


chemical reaction of, . 


chemistry of, . : : - 570 
chlorides of, ; 633 
chromogens of, . ; : . 626 
colour of, : 616 
comparative chemistry of, . 637 
composition of, 572 
creatinine of, 571, 572, 598, 638 


dextrose in, 6, 608, 881, 894, 920, 
926, 928 

diabetic. (See also Glycosuria, 
Diabetes. ) 3, 6, 14, 106 
drug-pigments in, x . 630 


estimation of acidity of, . 576 
ethereal sulphates of, 26, 467, 469, 

613 
fermentation of, 313, 582 
globulin of, 604, 605 
glycogen i in, E ; - wx 415 


PAGE 

Urine, glycuronic acid in, i 5, 618 
,, hematoporphyrin in, 260, 625, 629 
»,  hemialbumose in, 410 


hippuric acid of. See Hippuric 


acid. 


hydrochinon in, 606, 607 
hydrochloric acid of, . 633 
hydrofluoric acid of, . : 634 
indoxy] of, 607, 627 


influence of food on, 573, bie 19, 
585, 593, 610, 630, 682 


< of gastric secretion on, 359 

5 », muscular activity 
on,’ + d 916 
i 5, SX on, Aye 
inorganic constituents of, 572, 630 
inosite ins: - 3 4 . 606 
iron in, 635, 885, 886 
isomaltose in, 12, 612 
kresol in, 606, 607 
in lactation, 2 aut 
lactic acid in, 106, 109, 894, 907, 909 
lactose in, . ; 12, 611 
levulose in, 6, 611 
magnesium salts of, 634 
maltose in, 881 
mucin of, , 604 
mucoid, . : ‘ : Jag BD 
mucus of, : : { sD 
nitric and nitrous acid of, . . 634 
nitrogen of, 580, 684, 912 
nitrogenous constituents of, 580, 637 
uubecula of, : - : nce 
nucleo-proteid of, - : - 603 


organic constituents of, . 
ornithuric acid in, . . 602, 638 
oxalic acid of, : 


parakresol in, 606 
peutoses in, ; ; ; 3, 612 
peptones in, : - - 604, 605 
phenaceturic acid of, . 601 
phenol of, . 606, 607 


575, 578, 590, 632 


phosphates of, 
388, 571, 572, 591, 616 


pigments of, 


iS ,, pathological, 628 
poisonous properties of, . eo! 
potassium salts of, 633, 634 
proteids of, 5 85, 603 

> 55 NCeStSHorlys 3 smG05 


pyrocatechin of, : . 606, 607 


quantity of, : 573 
secretion of. See Uvi inary secretion. 
silicic acid of, . : . 634 
skatol carbonic acid i in, ; 467 
skatoxyl of, : : . 607 
sodium salts of; . : » 633, 634 
specific gravity of, . 573 
spectrum of, : 617 
sugar in. (See also Glycosuria, 
Lactosuria.) . 10, 608, 611 

», tests for, . 608, 610 
sulphates of, 631, 905 
sulphocyanate in, . : . 346 
sulphur of, : - - 630 
urea of. See Urea. 


See Uric acid. 

620, 628, 629 
urochrome of, . 618, 629 
uroerythrin of, 623, 628, 629 
variations in acidity of, . » 597 


uric acid of. 
urobilin of, 


INDEX OF SUBJECTS. 


PAGE 
Urine, volatile fatty acids of, 3 . 615 
;, Water of, secretion of, 641, 644, 647, 
656 

;, xanthine bases of. See Xanthine 

bases. 

Urobilin, . . 388, 474, 620, 628, 629 
ba physiological relations of, 622 
“e properties of, 621 
"3 separation of, 620 
a spectrum of, . 621 
Urochrome, . 618, 629 
- physiological relations of, . 620 
* preparation of, 619 
properties of, 619 
Urochloralic acid, 614 
Uroerythrin, - 618, 623 3, 628, 629 
- properties of, 7 023 
ae separation of, 623 
on spectrum of, 625 
Urorosein, . F : 628 

VAGUS NERVE, influence of, on gastric se- 
cretion, 537, 
539 


»» pancreatic 
secretion, 548 


” ” 9 


Valerianic acid, 470, 471 
Valeric acid, . 34 
Varnishing, effects of, : - 727 
Vaso-constrictor nerves of kidney, 646 


,, salivary glands, 
479, 504 
646 


3) 29 


Vaso-dilator nerves of kidney, 


9 »> >, Salivary glands, . 479, 

482, 504 

Vasomotor control of temperature, 854 
Vegetable albumin, leucine, and tyros- 

ine from, - : 425 

ee alkaloids, 34, 60 

55 ferments, coagulating, 334 

43 os diastatic a ail 

55 ss proteolytic, 51, 54, 330, 

403 

59 food in diet, 472 

35 gums, 14, 16 

95 proteids, é . 49, 51, 53 

Ee a crystalline, 2 AS 

iG 3 digestibility of, 51, 

333, 440 

3 33 glutamic acid from, 426 

a a as poisons, . 55 

Ps vitellin, . 52, 53, 54 


Vella fistula, ; ‘ : 
Venom of snakes. See Snake venom. 
Venous blood, fibrin from, 


368, 555 


167 


#5 gases of, - 154, 760, 762 

- hemoglobin of, = L85 

” jecorin of, 160 

Pe sugar of, 158 
Veratrin, influence of, on “body tem- 

perature, : : : 2 oa 

Vermes, hemoglobin of, 187 

»» respiratory ans of, . - 7102 

Verniz caseosa, 674, 675 

Vertebrata, hemoglobin of . 186 

J skin secretions of, 669 

Viperine, . 2 - : : oy ati, 

Visual purple, 122 


Vital action, 276, 283, 284 


997 

PAGE 

Vital capacity, 750 

Vitellin, 52, 69 

ry vegetable, : : 52, 53 

e coagulation temperature ‘of, 43 

is mechanical precipitation of, 43 

Vitelloses, . P P F P 50 

Vitreous humour, 122 

a mucinogen of, 62 

5 mucoid of, : 63 

»» percentage of fat in, 17 
WARM-BLOODED animals, temperature 

Of, .« : : : ; 787, 788 

Water, = - - : 7 1, 76 

;, absorption of, 433, 685, ‘689 

;, in coagulation, . : 7 OLS 

», extracting power, . . 270, 277 

;, in fermentation processes, 319 


+> 35 fluids of body, 127, 12835 129% 
153, 157, 183, 347, 559, 
641, 644, 647, 656 


Sane wOLZAaNs, 82, 85, 88, 95, 96 
ae se a decomposition, . 28, 29 
Oe disses, 2), 111, 113, 115, 12, 127) 
128, 129 
Wax, of bees, A 20 
», Chinese, 20 
Waxy degeneration, 74 
Weber’s test for indicanuria, 628 
Weidel’s reaction, 598 
Weyl’s reaction, 599 
Whartonian jelly, 62 
Wheat, ee of, 53, 54 
Whey, . - 134 
», proteids, 139 
White of egg. See Ey white. 

Witches’ milk, . 127 
Wood gum, . 16 
Wool, fat, : 675 
»  Sskeletin of, . : : el 

Work, influence of, on alkalinity of 
blood, 144 
= = ;, metabolism,. 911 

FF i ;, muscle gly- 
cogen, -. 105 

s a ;, number of 
corpuscles, 150 


respiratory 


exchange, . 715 

Worth of blood corpuscles, 152 
XANTHINE, - 60, 596 
FP "of blood plasma, 160 

35 ,, nervous tissues, 7 LG 

35 from nuclein, . : 66, 67 

5 of organs, 85, 86, 87, 88, 92, 


93, 98, 100, 101, 111 
as bases of nucleins, . 65, 66 
properties of, 597 
relation of, to uric acid, 67, 
596 
598 
= - = GEES 
amount of, 597, 598 


tests for, - 3 P 
of urine, 


2) 3? 29 33 


se aes estimation off 597 

» 93 Separation of, . 597 

Xantho- creatinine, : 60, 101 
Xantho-proteic acid, - : . ee: 


j — eh % Ng 7’ ‘ A: 5, y ; vy iL , ; 
BN ANU Ue eee 
ce INDEX OF SUBJECTS. 


; PAGE 

Xantho-proteic reaction, . : 2 PAT | SARANT s2g Si0 (Vine 

Reylese, + Sree - 2,38, 16,612 | Zymogens, . ‘ are 
Zymolysis, 320. See also Enz 


es effect of chemic al r 
cs b » >» 9) Concentrat 
Yeast, action of, on monosaccharides, . i 3 >> >, fermen 
s, fermentation, . Sh ARTS LAL : ducts 
be inverting ferment of, . 5) 1) 35 >> 95 tempere 
ng ne rim, ‘ : , . 3, 64 
‘ 4 


INDEX OF AUTHORS. 


ee se 

PAGE PAGE 

ABEL on Charcot’s crystals, . , . 94 | Allen on sugar in urine, - 3 . 608 
> > Melanin, ; . F sid22 > =, tidalvair : : : . 748 

>> >, Phymatorusin, P ; SP aVAl 99 “9 UKeA, 2 ; Do yA O84: 
Abeles on blood plasma, : : . 160 a urine, : : . 609 
wares.) diuretics;,*/x: 3 é - 648 Allihu on reducing pow Craw: rs - i 

> >» glycogenesis, : ; . 923 | Altmann on fat absorption, ‘ . 445, 455 

>>  », muscle glycogen, . ; . 104 Ae ;, intestinal emulsion, . . 448 
Pe; Spleen, B 3 sr toy P 5) Duclein, « . ‘ J Ley N66 
Abelmann on pancreatic juice, 443, 448, 459 | Alvarenga on skin temperature, . . 830 
», starch pale ae 3 435 Amermann on albumoses, . j . All 

Abelous on blood, P F - W52 ,, digestion, : F oe O22 
x a starch digestion, ; . 397 Ammon on milk, : ; : cue LF 

* ;> Suprar enals, ‘ . 949, 959 Anderson on saliva ary secretion, . « 524 
thymus, | : . 960 3 secreting cells, . ; . 938 
Abernethy on ‘cutaneous respiration, 725, 726 Andral on body temperature, : . 804 
ba ,, tidal air, : , . 748 55 x respiratory exchange, . 698, 722 
Abilgaard on vespiration, - : . 748 | Angelesco on body temperature, . = eval 
Ackermann on heat regulation, . . 856 | v. Anrep on CO-methemoglobin, . . 249 
f pyloric s secretion, : . 532 53 x gastric absor ption, : - 432 

Adami on renal secretion, . : a 656 Anselm on iron in bile, : $ 2 56 
Pes 45 SKID absorption, : : . 690 Anselmino on sweat, . . 670 
Adamkiewicz on proteid assimilation, . 878 | Ansiano on fractional coagulation, o, B48 
», a reaction of proteids, 47 Araki on chitosan, p 3 : POTS 

Addison on suprarenals, : . . 948 Be bas diabetes, : : ; - 927 
Adie on osmotic pressure, . ar 267 » 4s lasticactd, .- : ries 109, 895 
+> 5, semipermeable membranes, “265 Se. ws sarcolactic acids av; = LG 
Adler on lymph, . ? ; aeZ8S +> >, Sulpho- -methzmoglobin, . . 249 
Adrian on intestinal secretion, : . 555 | Argutinsky on meat, . . 873 
»> >, Salivary secretion, : . 495 3 ae proteid metabolism, - 913 
Aeby on bone, . , ; ; Pret PSWEatnees ‘ - 670, 672 
Eyl sor Gentine, . é 3 Slit? Aristotle on animal heat, k 5 2 832 
Affanasiev on bile, : ; - . 567 ;, Tespiration, . > 692 
BR ;, bilirubin, 5 F 2 663 Arkle on body temperature, . , 806, 823 

ms », gases of blood, . 762, 780 | Arloing on skin secretion, . 677, 678, 681 

37 pancreatic secretion, . 548 Arnaud on carrotin, 20, 21 

Akermann on pepsin, . i ; . 9331 9 ,, cholesterin, : : sem 
Albertoni on diet, : : . 877 | Arnschink on glycerin, - : - 882 
5 5 Uhy: roidectomy, . 939, 941 Arnstein on salivary nerves, . ‘ ae We 

», trypsin, . : . 336 53 ,, tension of gases, ; . 7184 

Albrecht on spectrophotometry, : OEZIS 33 ,, wandering “cells, . 450 
Aleock on Ammocete, . : : . 674 | Aronsohn on body temperature, 792, 863, 864 
Aldehoff on diabetes, . F : . 928 | Aronstein on ash-free albumin, . 30225 
fn Ap glycogen, 104, 918 Arrhenius on diffusion, : i) 2631284. 
Alexander on suprarenal extract, ~' 9950 dissociation, . . 261, 268 
Alexceff on body temperature, . . 804 | Arronet on blood, : - . 154 
Allan on biurates, : : . 588 | d’Arsonyal on blood spectrum, : . 225 
Allara on thyroid g gland, ; 940 93 ;, calorimeter, . x . 845 
Allbutt on body temperature, 788, 789, 799, ,, Tespiration, . 739, 742 
800, 806, 808 Arthus on blood ferment, . 161 

Allen on creatinine, . Ee) > 3, coagulation, 147, 168, 169, 170, 
BS 33 respiration, 695, 698, 735, 750, 754 171 

Be yess £3 of hydrogen, . 739 Pee?) fibrin; ‘2 ‘ : 167, 405 

Oe ata - >, oxygen, . - (36 ‘. ;, lacto-globulin, . - & also 


1000 
PAGE 
Arthus on liver ferment, 926 
ss 5, milk coagulation, 135 
Ascherson on haptogen membrane, 125 
5 ,, skin glands, 5 (ate 
Asellius on lacteals, 286, 302 
Ashdown on elycuronic acid, : 5, 614 
Asher on absorption of pr oteids, 900 
ay 5s) Lyman. 295 
+> 9) venous absorption, 303 
Astaschewsky on saliva, . 343 
Aubert on cutaneous respiration, 726, 727 
55.) iss, lk; : : 5 eli 
Ae ,, skin secretions, : . 680 
Auerbach on thyroiodin, . ; . 89 
Auld on suprarenal body, . : 5 
Autenrieth on fetal respiration, . - 731 
Autokratoff on thyroidectomy, 941 
Avicenna on mesenteric veins, : > 286 
Axenfeld on hematin, . ‘ : e250 
Ayres on chromophanes, : : 5 
BABES on pus, 3 . 84 
Bach on electrical currents, 683 
Baeyer on indol, 468 
Re bins Pettenkofer’ s 5 test, 5 ROTM 
Baginsky on bile, : . ayred 
Ss e body temperature, 863 
55 », coagulating ferments, 334 
ss lime in food, 886 
Bahlmann on amido- acids, : . 880 
Baisch on urine, . 605, 609, 613 
Baldi on bile salts, ; ‘ ct! 
> .) jecorim, 5 : : 86, 160 
a. jy5 Spleen,tat : : : a GY 
Balfour on bile, : 371, 560 
sor ee suprarenal body, . 957 
Balke on antipeptone, 420 
>> 3) Carnic acid, 103 
Barbera on absorption of proteids, 900 
bs utes, bile; : . 566 
Barbieri on cholesterin, ; ; . 24 
bs », leucine, . ‘ ee 
Bardeleben on gastric fistula, 537 


Barensprung on body temperature, 734, 798, 
799, 804, 805, 810, 811, 


,, skin absorption, 3 
Barfoed on sugars, . : : 5 lil 
Barkow on hiber nation, 


Barlow on osmosis, ; ; : - 273 
Barral on sugar in blood, . - 160, 161 
Barratt on cutaneous respiration, . 726, 727 
Barreswil on gastric juice, . 2 §(552.358 

~ gelatin, 2) 879 
y. Barth on tyrosin, : . 423 
Bartholin on lymphatics, 286, 288, 310 
Barton on hibernation, , - 198 
de Bary on digestion, 356, 429 
Baschkis on skin absorption, . 687 
Bassorin on bile pigments, 389 
Bassow on gastric fistula, 537 
Bastianelli on succus entericus, 398 
Batelli on sebaceous glands, . 676 
Battistini on muscle, ‘ 108 

», hervous tissues, wag, 
Bandelocque on fetal respiration, 731 
Baudrimont on respiratory exchange, 734 


Bauer on fat formation, - . 902, 934 
32 »; proteid absorption, 


| 


INDEX OF AUTHORS. 


PAGE 
Bauer on respiration, . ; - 107, 8 
Baumann on alcapton, . : : 607 
a ,, alkaloids in urine, . pl 
- », aromatic substances of 
urine, ‘ 605 
A ;, cadaverine, 5 : Senos 
ae », cystine, . : - 602, 603 
is », indol, . 468 
ae 5, proteids, 26, 34 
3 », ptomaines, : 466 
oO ,, putrefaction, . i . 467 
ce ,, putrescine, = . 60 
S ,, reducing power, . = ty 
r ;, sulphates of urine, . » 926 
a ,, sulphur of urine, 632 


thyroiodin, . : > ey 


i. o tyrosine, 467 
urine, 605, 606, 609, 630 

Baumert on gases of alimentary canal, 730 
33 3 respiration, 699, 703 
Baumgartner on respiratory exchange, . 734 
Baumler on hyperpyrexia, . : . 823 
Baumstark on protagon, 118 
Bayer on choline, ‘ : : s 21 
5 485 ptyalin, . = BPa 
Bayliss on body temperature, 826, 830, 855 
s> 35 electrical currents, 517, 682 

3% <9 Lymph; 290 


2 », salivary g glands, . 


517, 843, 896 
Beale on cells, . 869 


BS iss intraglobular crystallisation, 191 
Bean on asphyxia, 2 . 744 
Beaumont on gastric secretion, 355, 402, 

536, 540 

», fistula, 537 

Béchamp on carbohydrates of milk, 133 
9. oo » Cgg white: : Aol] 
Bechterew on salivary secretion, 485 
Beck on muscular metabolism, 916 
v. Becker on cane-sugar, - - 398 
aA ;, pancreatic secretion, 551 

- 55 Saliva: ee ; . 498, 499 
Beckmann on freezing point, * . 269 
Béclard on heat production, . : 842 
Becquerel on blood heat, 828 
eo , milk, 128, 130, 131 

,, Skin varnishing, . =. he 

Beddoes on respiration, : - - 735 
Beer on Lambert’s law, 214 


Behrend on uric acid, 


586, 587 
Bein on lipochromes, 21 


Bel on stereochemical isomerides, . . 106 
Bell on reserve air, , . 749 
Bence-Jones on animal alkaloids, 6 swelbo 

oe a quadriurates, - 588 


410, 579, 608 


5, urine, . ‘ 
v. Beneden on animal heat, 791, 803, 847, 864 
a “3 hemoglobin, , 1 ASE 
5 _ respiration, 848, 706, 711 
Benedicenti on respiration, . 22 ie 
Benedikt on muscular metabolism, sn29s 
Beneke on cholesterin, - : i Pay: 
Benjamin oncasein, . ‘ 137 
Bensch on biurates, . ; 588 
3S Sami, as H 130 
Berard on fractional coagulation, : . 48 
Berdez on phymatorusin, . : 121 
Berend on alkalinity of blood, . 144 
Berenstein on respiration, 749, 750, 751 
Berg on cutaneous respiration, 7238, 724 


— 


INDEX OF AUTHORS. 


PAGE 

Berg on expired air, . 7155 
99 99 Yespiratory exchange, 698, 721 
Bergeat on digestibility of pr oteids, 333 
Bergeen on gases of alimentary canal, 730 
Bergengruen on blood corpuscles, . 191 
Berger on blood heat, 828 
Bergmann on animal heat, ; . 788 
a », heat regulation, 851, 852, 853 

e 5, sweat, : - 673 
Bergonié on respiration, 698, 700 
Berkeley on renal nerves, sa 659 
oe ;, salivary nerves, 525 

,, thyroid extract, 943 


Berlinerblau on lactic acid in blood, 159, 


160 
” muscarine, . 60 
Berlioz on urine, 573 


vBernard on acid of gastric juice, 352, 353, 533 
asphyxia, 744, 745 
body temperature, 809, 815, 820, 
824, 826, 828, 829, 
840, 841, 855, 858 


be) ”” 


99 2? 


(OX », cane-sugar, 398 
+ 3, cerebro- “spinal fluid, 184 
3 ,, chorda tympani, . 482 
- », dextrose, . § 158, 914 
5, diabetes, : 927 
Rs ;, diabetic puncture, 660 
* ,, digestion of fats, 443 
=f >, gas analysis, 760 
5 ,», gases of alimentary canal, 730 
i en DlOOd. 60,0763; 165, 766, 

780 

5 PSaSUIe |ILGe, 350 
.. BRRELALIDS a8 x3 oie) 
a », glycogen, 15, 16) 397, 917, 918 
922 

A », glycogenesis, 922, 923, 924, 925 
+ », glycolytic ferment of blood, 161 
As ,, heat production, 843 
5 », internal respiration, oy esl 
:. ,;; intestinal emulsion, 447, 448 
55 ;, pancreatic chromogen, 427 
- cS 55 digestion, . 414 
- a5 a fistula, . 366 
i, 5 33 secretion, 368, 547, 550 
5 ;, paralytic secretion, 6 ule 
5 », Pigeon’s milk, 676 
is ,» proteid food, 878 
a ;; Puncture diabetes, . 926 
= ;, Tespiration of CO, 740 
-, ,, respiratory exchange, 694 
fs 5, salivary glands,. 482, 483, 516, 
625, 896 

a np >» merves,. 482, 483, 492, 
524 

- - », secretion, 484, 490, 491, 
492, 495, 504, 505, 523 

r 5, submaxillary ganglion, 480, 481 
i ., temperature of blood, 827 
Bernhart on nervous tissue, . mS 
Bernouilli on respiration, . 704 
Bernstein on muscle, 99, 782 


8 », pancreatic secretion, 547, 548, 

553 

5 x3 re fistula, 366 

. », residual air, 749 

AS ,, Specific heat, 839 
Bert on alimentary respiration, . 730 
mm 55 asphyxia, 748, 744, 745, 746 
»> 99 Caisson disease, 737, 738 


IooI 

PAGE 

3ert on frequency of respiration, . . 7153 
5» 9, gases of blood, 761, 762, 763, 768, 
769 

5» 9) heat production, 840, 841 
s> 5, hibernation, a, FOG 
ae 73) Lacteals ers 2 = 302 
+> 9) lactose, 665 


oa eee ROLIgIN of respiration, 692, 753, 780, 


781, 782 

»» >», reducing substance of mamma, 124 
+» 55 Tespiration of CO., . 739, 740 
” ” 99 ) a 2 of 736 
.» 5, respiratory exchange, 720 
Berthelot on animal heat, 839 
> ,», chitin, 74 

> ,, coefficient of distribution, 354 

i , heat of combustion, . 834 

Pe , pialyn, = 340 

- , temperature of blood, 826 

, tunicin, é 16 

Berthold of hibernation, . 7198 
Berthollet on respiratory exchange, 694, 711 
Bertrand on skin secretion, a) 6f3 
Berzelius on biliverdin, j : . 382 
sf ,», crystallin, . - a 23 

55 ny HESOUM, : : = il 

5 , lactic acid, 108 

5 35 ’ saliva, : - 348 
Bettmann on thyroid feeding, - . 944 
Bial on diastatic ferment of blood, . 160 
£ ferment of liver, : c . 926 
Biarnes on blood, : 152 
y. Bibra on liver, : - c outst) 
Bichat on exhalant arteries, . . 287 
Bidder on absorption of bile salts,, 392 
a8 ;, bile, - . 560, 565 
ms 55 body temperature, §03, 809, 866 

5 ,, fat absorption, . : - 460 

& ,, ferments, . 320 

3 ,, gastric fistula, 7 Bon 

3 +3 IUIce. : . 352, 538 

:S ;, inanition, ; . 889 

A ,, intestinal secretion, 555 
% >, mucus, : 344 

5 5, pancreatic juice, . 368 

B 3 ,, proteolysis, . ‘ : - 9323 

= ;, renal secretion, . 7 OO 
Es ,», respiration, . 707, 718 

tS (salivary. 347, 348, 487, 505, 523 

Bidloo on red corpuscles, . 188 
Biedermann on electrical currents, 519, 684 
,, skin glands, . . 683 

Biedert on milk, . 138 
Bied] on grape-sugar, . 880 
5: are suprarenals, 951, 958 
Biel on milk, : 128, 131 
Bienstock on bacterial digestion, 466 
Biernacki on pepsin, . ; oo 
» trypsin, . : ° . 337 

Billard on thymus, ; 5 Bao 
Billet on animal heat, 789, 799 
Billroth on body temperature, 5 fist 
5 spinal injury, . 861 
Bimmermann on maltose, 397, 398 
Binet on bile, 392, 563 
Birch on bile, 560, 561, 562 
Biot on respiration, 704 
+» 35, swimming bladder, 705 
Bischoff on inanition, 5 889 
ne ,», Tespiration, 731, 735, 758 


1002 
PAGE 
Bistrow on hemoglobin, , ; - 242 
Bizio on glycogen, ; 15, 104 
ee SW eat, : : 5 (O7A3 
Bizzozero on blood platelets, é 7, 56 
Pe », Salivary cells, . : 7H) 480 
,, sebaceous glands, é . 674 
Blachstein on lactic AGI yr 107 


Black on animal heat, 817, 832, 839 

5» 5) Tespiration, 693, 694, 742, 757 
Blackman on muscular metabolism, pemonel! 
Blagden on body temperature, 786, 814, 851, 


852 

5 , freezing point of solutions, . 269 

sn ’ heat regulation, : SUS feh3)! 
Blanchar d on hemoglobin, , : ae Si 
Blankenthorn on protagon, 3 : gail) 
Bleibtreu on blood, j : . 149 
x - corpuscles, ‘ ee 149 

5 rf  foodstutts, : oro 

* ;, muscular metabolism, oa OHS 

FR ,, thyroid feeding, ; . 944 
Blennard on proteids, . : : albeit 
Blitstein on intestinal secretion, . 01556 
Blix on blood corpuscles, —. f . 148 
Bloch on respiration, . : F q Cee 
¥> 9) Sweat centres, : : 5 aif) 
Blome on acidity of muscle, . : . 108 
Blomfield on fish slime, F ‘ . 676 
Blondlot on gastric fistula, . . nao 
5, juice, x . 3852, 360 

Blosville on body juice, . 352, 360, 537 
,, temperature, . - 812 

Blum on egg albumin, . : 050 
Blumenreich on parathyroids, ‘ - 940 
55 + i te eae : . 943 
Blumenthal on milk, . ‘ =, Wo4 
Blyth on cobric acid, ; . : se 
Boas on gastric juice, ; - 356, 366 
wa) #5) Dialyn, ; : : . 3840 
 ) rennin: : : . 3884, 335 
Babe kG trypsin, ; F . 837 
Bochefontaine on salivary secretion, . 485 
Bodtker on estimation of urea, . By Key! 
Boeck on respiration, . : af 107, Ws 
Boedeker on alcapton, . 607, 630 
isa ,, chondroitic acid, F » wel 

ye », milk, 5 : : . 180 

a PUSS : ‘ 5 = oo 

Boeklisch on putrescine, . : = 260 
Boerhaave on animal heat, . . 815, 832 
Bogdanow on muscle-fat, . F 7771106 
Bogoljubow on bile, . : ; . 784 
Bogomoloff on bile, 3 f ; . 390 
,, bile salts, : : . 378 

Bohland on foodstuffs, . : , a tif) 
», muscular metabolism, a 91s 

Bohien on electrical currents, i 7) 684 
», gastrie glands, . : . 683 

Be ihm on lactic acid, . i : . 109 
~*),, muscarine.. #- ; : 260 
i es muscle elycogen, ; : a. Biles 
»» 9, Sugar formation, . 5 EOD 
eos bay Sims : 5 , . 9338 
Bohr on coagulation, . ; E 3. alyis 
3» 3, CO, hemoglobin, 242, 243 
+> 355 gases of blood, ‘ . 69, 777 
+» 5, hemoglobin, 767, 768, 773 
>> 5, hemataérometer  . 4 = EG 
ee anilkefate ; : 133 


s> 3, Oxyhzmoglobin, 192, 205, 225 


INDEX OF AUTHORS. 


PAGE 

Bohr on respiration, . $55 TA me 
5» 5, swimming bladder, . i ~ 105 
Boileau on body temperature, - - 813 
du Bois Reymond on electrical currents, 517, 
681, 682 

x rf », electro-osmose, . 688 

= < ., lactic acid, . PaO 

3 < », muscles, . 840 

cs $ i reaction of muscle, 99 

59 a3 », torpedo organ, . 111 
30kay on lecithin, 5 : 1 . 463 
55 * 5 muclein; ‘ : nono 
Bokorny on albumin, . : : ate 26 


3 3 protoplasm, \ i 0 388 
Boldt on muscle glycogen, . 5 ee 90'S 


Boll on torpedo organ, . : : “soled Ula 
Bonafous on animal heat, : : 825 
Bondonneau on starch digestion, . = 1895 
Borelli on inspiration, . : ; er 33) 
Bornhardt on proteids,. ; : ey 41 
Bornstein on fats of blood, . : P59 
Boruttau on inosite,  . . - > 105 
ee - muscle, : - 5s wy 

AE elycogen, 4 104 

Bosanquet on animal heat, 787, 789, 802 , 813 
Bose on pituitary extract, . : : ” 948 
Boshard on leucine, . E . er 9298423 
Bostock on animal heat, . : . 832 
i ,, respiration, . 692, 731, 749 
Bottazzi on spleen, : - : > seOs 
36ttcher on dextrose, . 610 
ss 53 intraglobular crystallisation, 191 
Bottger on Charcot’s crystals, . o. #04 
- ,, sulphocyanate of saliva, . 845 
Bottomley on heat formation, . . 840 
Bouchard on leucomaines, . : OL 
Bouchardat on gluten, . é S ~ a 53 
,, starch digestion, . . 393 

Bourneville on body temperature, . 864 
», mMyxcedema, . : - 940 

Bourquelot on maltose, : : = 6007 
», succus entericus, ls » 1897 
Boussingault on respiration, . . 695, 706 
Bovet on putrefaction, . c : . 468 
Bowman on urinary secretion, 639, 640, 652, 
: 653, 655, 658 

Boyle on effects of cold, ‘ ' 817 
+> 39 gases of blood, ; : : WT 
»> 5) Yespiration, . A . 693, 704 
s> 5, thermometer, . : - 2 @i85 
Braconnet on gastric juice, . : . 352 
leucine, : : . 421 

Bradford on ablation of kidney, : a SBM 
” ,, diuresis, . 649 


a i electrical currents, 517, 518, 682 
- ,, heat regulation,. F ny odo 


33 ;, renal nerves, . . 644, 646 

3 4 salivary secretion, - 522 

ae ,, section of chorda ‘tympani, 520 

i gant abs Jacobson’s nerve, 521 

Ne A sympathetic saliva, . . 523 

», urinary secretion, 656, 937 

Brainard on snake venom, . 3 PE 7 
Bramwell on proteids, . ; - . 44 
Brandl on melanin, . F F «eel22 
i; ,, phymatorusin, . ’ » anole 

y. Brasol on diuretics, . : 4 . 648 
37») hydremia, F : ./ 294 
Braume on heat production, : 843 
Braun on salivary secretion, 485, 492 


INDEX OF AUTHORS. 


PAGE 

Braune on skin absorption, 686 

Bredert on milk, . : 138 

Breed on brain, ; 77 

Brensinger on cystine, . 602 

Breschet on blood heat, 828 

As ,, Skin varnishing, 727 

Brewster on spectrum, . 208 

Bricon on myxcedema, . : 940 

Brieger on alkaloids, 59, ‘60, 61 

+ ;, aromatic substances of urine, 605 

x ,, body temperature, 867 

> ,, indol, . : 468 

a ;, nheuridine, 60 

Ee ;, ptomaines, 466 

_ 5, putrefaction, 467 

»> 5) putrescine, . 60 

ei », Skatol, 469 

- s3 skatoxy], 628 

Briesacher on thy roidectomy, 940 

Bright on fat absorption, : 459 
Brisegger on intraglobular crystallisa- 

tion, 191 

Brodie on blood platelets, = 156 

he 53 body eae 857, 858 

¥, 1) 5 Casein, 3 ae Loi 

BSH «55 coagulation, . 145, 171 

BURP nucleo-proteids, . 68, 81, 83 

32 5) pancreatic casein, 137 

Priies s2 5 juice, . 2 bE 

+> 3) proteids, 24, 32, 34, 41, 165 

»> ~ ») Spinal injury, . 860 

;, sulphates, 26 

Bromeis on milk fats, 133 

Brosicke on bone, ill 

Brown on achroodextrin, 396 

»» ~ », carbohydrate absorption, 435 

>> ~~ 9, cerebrins, 4 , 120 

3 6. 53) dextrin, 12 

ee oc; diastatic ferments, 12, 13 

a >, enzymes, 397, 399 

»» 5, fat absorption, 452 

% «> galactose, 7 

o 5 annlin; -- 14 

so, ptyalin; 328 

§, ,, reducing power, : 7 

»» 5, starch digestion, 394, 397 

succus entericus, 398 

Brown- -Séquard on body temperature, 812, 

821, 855 

* ,, generative glands, 937 

. ,, hibernation, 798 

ne ,», pituitary extract, 946 

a »» respiration, 739, 742 

nA », Ssuprarenals, 948, 949 

,, thyroidectomy, 942 

Bruch on intraglobrlar crystallisation,. 191 

Bruck on animal heat, 862 

Briicke on acids of gastric juice, 356, 360, 533 

»> 5, bile pigments, . 9382, 387 

» 3, coagulation, ; 179 

s> 3; dichroism of blood, . an Be 

> >; digestive solutions, 323, 536, 542 

» 5, emulsion, 445, 446 

>> 9; erythrodextrin, #11395 

5». 5, fat absorption, 449 

> 9», gastric fistula, 537 

> 99 glycogen, 15 

>> 9) hippuricacid, 601 

SS , isolation of enzymes, 314 

Fale 59 *} lymph flow, 302 


| 


Briicke on muscle glycogen, . 


t » 5) OekoIas , 3 3 pos 

Pe >, pepsin, 97, 331, 333, 404, 542 

35 ;, Piotrowski’s reaction, siivt4s 

»> 9; pore diffusion, 274, 275 

BS 5, precipitation, 40 

- ,, proteid digestion, . 405 

Pe », ptyalin, 329 

-F ;, red corpuscles, 188 

oP ;, starch, = 11 de 

b », Sugar in urine, 608, 609 

, zymolysis, 320 

Bruguiére on hibernation, 798 

de Bruin on bile pigments, 391 

Brummer on milk, 128 

Brunner on proteids, 41 

Brunton on alkaloids, 59 

rs ;, bacterial digestion, . 470 

- ;, intestinal secretion, 555, 556 

9 ;, nuclei, 65, 81 

- », saliva, 343 

;, shake venom, 56 

Bryant on body temperature, 864 

Bubnow on thyreoproteid, 2 EE, 

Buchanan on fibrin ferment, . 168, 179 

,, gases of blood, . Sho 

Biicheler on oxyhemoglobin, 199, 200 

Buchheim on ammonia in urine, - 907 

5, gastric juice, 360 

Buchner on gases of lymph, 783 

¥ i gelatin, 71 

Buchser on body temperature, 802 
Buequay on respiration of compressed 

cue te 738 

Budge on body temperature, . 855 

s> 3, intestinal secretion, syisae 

Buff on salivary secretion, 492, 512 

Buffon on asphyxia, 745 

Buisine on sweat, . : 673 

Bunge on ammonia in urine, 907 

>> >, @Sh of serum, 772 

L. . sr ibUey : : : > oft 

2) blogds 148, 153, 154, 157, 188 

RS Use Mp wremasess 157, 773 

L. eudieti = Till 

Be a's 5 digestion of cellulose, 470, 471 

eee foodstuffs, 873, 881, 882, 885 

rrresiaele juice, : 361, 363, 364 

> 9», glycogen, 917, 918 

»> 99 hematogens, 68, 69 

s> 9, hemoglobin, . 203, 768 

s> 3) hippuric acid, 893, 906 

»> 3) ilntestina] emulsion, 448 

» 3) iron in feetus, 885 

29 39 32 39 food, ~ 885 

., 5, lime ini food:.; 886 

GOS: os, Ssaltsofurine: 635 

fie );;. male 662 

»> », muscle ash, E . 109 

ss 9) potassium in food, 630, 634 

s> 3, proteid digestion, . 899 

5» 9, respiration, 700 

oh jg Saliivas 327 

yaa 53° Salts of food, . : . 884 

a 55 fees milk, 128, 131, 132, 662 

ys 5, Soa: body, : 77, 78 

,»  »3 Syntheses in metabolism, 893 

», urine, . a0 1552601 

Bunsen on extinction coefficient, 214 

»» 9) gas analysis, 760 


1004 INDEX OF AUTHORS. 


PAGE PAGE 
Bunsen on oxygen of blood, . : . 766 | Chischin on Pawlow fistula, . E . 537 
5» 9) Spectroscope, : : . 216 | Chittenden on albumoses, 50, 407, 408, 409, 
Buonaparte on viperine, : : 5 aS 410, 411, 412, 413 
Burchard on cholesterin, : 3 - (28 3 ;, alcohol, : : PE) si h'4 
Burckhardt on blood proteids, : =) el62 i », anti-albumid, : . 406 
Burdach on asphyxia, . ; ; 1 p/AD Ae », bile salts, . - . 092 
7 », lymph, P 287 “9 ;, bromelin, . é wlhSD 
Burdon Sanderson on balance of nutri- an », caseinogen, . ‘ 5 alsty 
tion, : ; = : om 33 5, copper albuminate, 26 
Busch 0 on gas pump, 5 - : 5 Tey 5 ,, digestion, . 47, 322, 406 
+> 5, gastric absorption, ; - 432 oe 7 dyspeptone, ‘ j . 429 
Butlerow on methylenitan, . : 5 5 e ,, elastin, , 71, 72, 430 
Biitschli on respiration exchange,. 702, 710 i »> enzymes, i a . 314 
a ,, fractional coagulation, . 43 
CAHN on cataract, : : ‘ sles a >, gelatin, : 47, 429, 430 
»» 99 gastric juice, . ; ‘ . 358 33 3 ». peptone, lie = eval 
bh seeretinanant. J , ei l2t a 35 glycocinie;i ms ‘ -. 08} 
Cahours on lecumin, ’ ; ol: 3 »» glycogenesis, ; 26 
Callenfels on body temperature, 3 SoD = 57 milk ‘ ’ 28 
Calmette on snake poison, . : 56, 58 5 », muscle, : : VEE 
Camerano on salamander, . : Fe . a », glycogen, . a 04. 
Camerer on milk, . : F A « 28 oe », Myosin, 5 : 97, 98 
55 SV UncraciGas me 67, 594, 595, 597 3 ;, neurokeratin, < R27 
. xanthine bases, . ; . 598 A >) peptones,) +. 25 
Campbell on bile, . : : . 93886, 390 si », proteids, : 492, 46, 333 
Camus on lacteals, , ‘ ‘ > o02 Pa », proteoses, . 45 
Canalis on thyroidectomy, ‘ ‘ eno39 $e », ptyalin, : : 329, 330 
Caparelli on diabetes, . : : - 928 x5 5 uSalivase : : 328, 344 
Capobianco on thyroidectomy, ; . 941 3 ;, tendon, : : ay 
Capranica on lutein, . : 01420 i, Hs 55  anucinjaier 5: to? 
os >, sweat, . ‘ ‘ a ie 5 5, trypsin, 5 H . 338 
Carlier on coagulation, - : ; . 169 vegetable proteids, iu) od 
Carter on body temperature, . 803, 809 Chopinet on thyr oidectomy, . . 942 
Casali on skin secretion, : ; 673 | Chossat on body temperature, 802, 803, 809, 
Caseneuve on fat formation, . é 902, 934 853, 857 
Casey on body temperature, 788, 789, 799, 3 ,, lime in food, ‘ 886 
800, 806, 823 | Christiani on skin temperature, 5 5 A 
Cash on bacterial digestion, . : 464 | Chrzonszczewsky on urinary secretion, . 653 
»> 9; digestion of fats, . ‘ . 448 | Chtapowski on saliva, . { : . 484 
+> 9, fat absorption, : : . 459 | Church on turacin, ; “ 2 sO 
»> 5, Intestinal emulsion, : 448 | Churchill on spinal injury, . - 860, 861 
say. 95 Teaction of intestinal contents, . 452 | Cienkowski on cellulose, ‘ . cpl 
Castle on body temperature, . . 816 | Cima on filtration, - i : . 280 
Cavazzani on body temperature, . 808 | Claronspirometers, . 3 - = Woo 
5 ;, diastatic ferment of blood, 161 Clarke on spinal i bie A : peso 
», glycogen, . : : . 925 | Clemm on milk, . : =, 27, £28 
BS ;, starch absor ption, . . 4385 Cleve on cholalic acid, . ; : A Bisill 
Cazeneuve on milk, : ‘ ‘ . 126 | Cloetta on liver, . : % ; 86 
Celsius on thermometer, : : 5 Se sal olsgespleen; 5 : : 5 uBys 
Chabrié on proteids, . t . 41 | Cloez on skin secretions, : : . 673 
Chandelon on muscle glycogen, ; 5) l05 »» 9, Suprarenal body, . . 0 
Chaniewski on fat formation, : . 932 | Cohn on amyloid substance, . : 3, OTe 
Chapoteaux on gastric juice, .  gDA6 »; >, fat absorption, : : ~ 1459 
Charbonel- Salle on pigeon’s milk, . Oe ay 03) gastrich lice ym Z : . 364 
Charcot on body temperature, : . 805 % 5, leucinetve : : 3 a2. 
Chateauburg on urine, . : : . 604 +> 5) proteids, 5 ! ; Sane 
Chauveau on blood gases, . . 763, 764 , salivary glands, . ; AUNT 
o ;, carbohydrates, . : « 99/9 Cohnheim on blood, . 143, 151 
3 5, CO, of muscle, . ; «» 92, 5 ss internal respiration, Ae ffs 
a3 ;, dextrose in blood, . 158, 915 ne 5 Lympleee : . 296, 298 
5 », metabolism, . : - 923 5 », pancreatic diastase, . . 340 
5 ;, muscle, . . 841 Es », ptyalin, . ; . 828, 330 
, respiratory exchange, . 841 », zymolysis, : . 320 
Chavvas on. aqueous humour, ; | 122 | Cohnstein on alkalinity of blood, ~ ie 
Chevalier on nervous tissues, : =» 116 5 5, foetal blood, . - - 32 
Chevreul on milk fat, . ; : 5 1B 9 gael ss respiration, . 732, 733 
Children on gastric juice, . 3 . 352 lymph - 295, 304 
Chiodera on urochrome, : 620 | Colasanti on body temperature, : - woe 
Chischin on gastric secretion, 541, 542, 545, 76 5p CuTare Wee ; : . 842 


546 - a effects of cold, . ; . 823 


INDEX OF AUTHORS. 


PAGE 

Colasanti on respiration, 695, 700, 701, 707, 
711, 848 

f », sarcolactie acid, 106, 616 
Colby on milk, . : 131 
Colin on fractional coagulation, : ards 
aes; lymph, - 302 
ths * salivary ¢ glands, 477 , 489, 490, 491 
secretion, ‘ : 490 


Collard de Mar tigny on asphyxia, . . 744 
,, blood heat, . 828 
” 2” ” >»  §ases, . 758 
3 cutaneous re- 
spiration, . 726 


be) bed 


3) 2) 


Collmar on heat regulation, . : . 858 
,, suppuration, - - Oe: 

Colls on blood, . : : . 160, 161 
ee creatinine, = 5 ; seek 
eas proteids, . : : : sve aa 

»> », Sugar in urine, ‘ : . 609 
Commaille on milk, . ; F =) 128 
Configliachi on respiration, . : . 704 
Contejean on coagulation, . SS, 8 
i », gastric secretion, . . 534 

93 », muscular metabolism, BE DUE: 
Cooper on coagulation, . : : 5 l(t 
Copeman on bile, . : . : 5 yi 
o a blood, : - . 143 

rp e heematoporphyrin, : - 625 
Coppet on freezing point, . - - 269 
Coranda on salts of food, . 883 
Corin on body temperature, 791, 803, 847, 864 
»> 3, fractional coagulation, . 43 

y> 9) Tespiration, 706, 711, 848 
Corneyin on milk secretion, . - . 664 
- ue phloridzin, ; : 4/921 
Corvisart on trypsin, . . . 338 
5 ,, tryptic digestion, 414, 415 

de Coulon on pituitary body, . 946 
Courant on caseate of lime, Pliog 
son 5; mulk; . : . 126 
Cramer on coagulation, : » 472 
ee ibroin, é : A ee nAO 

,, muscle glycogen, . 104 


Crawford on body heat, 819, 826, 827, 832, 
838, 839, 844, 846, 847, 852 


#5 a) heat of combustion, : . 834 


" », Tespiration, 709, 711, 757, 780 
Creite on inosinic acid, . : - 108 
Cremer on glycogen, . + . ou ld 

fy epenbOSeS, =. . - 3 
»> 3, phloridzin diabetes, 920, 921 
Cristafulli on respiration, . c . 742 
Cristiani on thyroidectomy, . - 4989 


Crombie on body heat,. 787, 799, 800, 802, 
804, 807, 809, 810, 811, 
813, 814, 825, 866 


Crookewitt on spongin, : : 5 eS 
Croon on respiration, . ; ; - (692 
Cruikshank on cutaneous ea 725,726 
», lymph, . : oa Zu 
Cumberland on animal heat, ; . 816 
Cummins on bile salts,. 5 . Oo 
53 5, proteids, . - : . 333 

», trypsin, . . 338 

Cuny Bovier on body temperature, 807, 820, 
821, 825 


Currie on body heat, 818, 819, 823, 846 
Curtius on gelatin, : oo fil 

5» 5, hemoglobin, : - > 2 
Cutler on body temperature, : - 812 


1005 

PAGE 

Cuvier on hibernation, : ios 

Cybulski on suprarenal extract, SB, SB, 

967, 958 

Cyon on thyroid gland, - . 945 

Czermach on animal heat, . 5 - 793 

Czermak on salivary nerves, . - 483, 494 

3 secretion, . . 806 

Czerny on absorption, : - ‘ . 437 

» ,, digestion, . : : . 442 

DAGNANI on bile, , 561 
Dahnhardt on ferment of mammary 

gland, . : 140 

SS lymph, ie 182, 783 

Dalton on respiration, . 696, 748 

+» 5) Specific heat, : : . 838 

Damrosch on body temperature, . 789, 798, 

a 802, 809 

Dana on succus entericus, . 398 

Danilewsky on caseinogen, . - - 136 

6 5, enzymes, - - . 9340 

* », foodstuffs, . F . 835 

$e », heat values,. 834, 838, 874 

», pancreatic juice, . 337, 338 

a », proteid digestion,. 400, 415 

Dareste on respiration of embryo, . . 733 

Darwin on proteolytic secretions, . . 330 

Dastre on biliary fistula, . : . 460 

“A ,, coagulation, . $ : 2 178 

45 yeenzymes, . ; : - sree 

et, Pe ibrin ; ‘ : lea 

a5 », galactose, . P , . 880 

i 5, lactose, ‘ : : . 399 

3 », liver ferment, . : e925 

a », lymph, , ‘ é ie liSil 

# », maltose, . ; . a ey 

»» peptone plasma, . . 5 MGs 

fr respiration, . : . (42 

Davenport on body temperature, : 2 SG 

Davidson on pepsin, . : - . 332 

Davies on thyroid, : ; : - $89 

* », Uuricacid, . : F Se hs 

Davis on phymatorusin, - 122 


Davy on body heat, . 786, 787, 788, 789, 
791, 793, 799, 801, 804, 805, 806, 

807, 809, 810, 811, 812, 813, 814, 

820, 827, 828, 830, 839, 840, 850 

ss 3: gases of blood, : 5 US Hie 
5> 9, Tespiration, 698, 735, 748, 749, 
750, 751, 754 


Dean on heat regulation, . : . 856 
Debezynski on body ae Kara + 80% 
Decaisne on milk, ‘ 4) 128 
Delaroche on body temperature, 815, 852 
55 », Tespiratory exchange, 704, 709, 

711 

Delépine on melanine, . : : enl22 
Delezenne on coagulation, . . 146, 178 
Demant on creatine, . ; : . 100 
55 », succus entericus, ; . 399 
Demarcay on bile, : = solz 
Demarquay on body temperature, . 821 
Dening on thyroid feeding, . : . 944 
Denis on plasmine, - - . 164 
»> 5) proteids, ; : : » ., 42 

os) ») EeSpiration, —- P : = 032 
Deschamp on chymosin, - : . 384 
Desfontaines on animal heat, : » S16 
Despretz on animal heat, 832, 844, 846 


3 », Tespiration, : : ES 


1006 
PAGE 
Detmar on ptyalin, : 329 
>> 99 Tespiratory exchange, : shesO2 
Devoto on proteids, : 40, 41 
Deweyre on glycogen, . 918 
Diaconow on cerebrins, Spee AY) 
i ;, lecithin, . i 22 
;; protagon, 118 
Dickinson on leech extract, 147 
a ,», salivary nerves, 484 
AG secretion, 615 
Diest on fcetal respiration, 731 
Dietrich on pepsin, . : : - 332 
Dissard on respiration, . 724 
Dittmar on respiration of fishes, 704 
Dobroslawin on intestinal secretion, 556 
Dobson on body temperature, 814 
Dodds on bile secretion, 569 
Dogiel on salivary nerves, 525 
Dohmen on respiration of oxygen, . 736 
Dolinski on pancreatic secretion, . 549, 551 
Dominicis on diabetes, . 928 
x ;, suprarenals, 949 
a ,, thyroidectomy, 939 
Donaggio on parathyroids, 941 
Donatti on thyroid extract, . . 943 
Donders on animal heat, 788, 855 
$3 ,, CO-hzemoglobin, - 2388 
os ,, lymph-pressure, . 299 
Donkin on hyperpyrexia, - - $823 
Dormeyer on fats, ; 17, 96, 105 
Dorn on sweat secretion, 679, 681 
Draconow on spermatozoa, 5 UB 
Dragendorf on milk, 131 
Drasch on skin glands, 681 
Drechsel on biuret reaction, . 49 
- ,;, elastin, 72 
ee ;, 1odo-gorgonic acid, 90 
“ ;, jecorin, 86 
~ ,, keratin, 73 
= ,, lactic acid i in blood, . 159 
+ ,, lysine and lysatine, 32, 33,426, 427 
“5 : Pettenkofer’s test, on aot 
a , proteids, 24, 27, 32, 52 
< ,, thyroid gland, . 938 
urea fornittion? : : - 907 
Dreser on "glomeruli, A ak, 
= ,, osmotic pressure, . 272, 650, 651 
x ,, reaction of urine, . = 4ODt 
Drouin on alkalinity of blood, 144 
Druebin on blood platelets, . : saulo6 
Dubois on hibernation, 794, 796, 797, 798 
Dubrunfaut on digestion of starch, 394 
Ducceschi on thyroidectomy, 941 
Duchamp on body temperature, . . 805 
Duclaux on milk fats, . ~ 133 
Ducros on skin varnishing, . 5 20 
Dufourt on glycogen, 920, 925 
e ;, muscular metabolism, . : 915 
Dufresne on ptyalin, : 330 
Duggan on fractional coagulation, 43 
Dulk on air chamber of egg, 735 
Dulong on animal heat, 832, 837, 838, 844, 846 
>> 9) Tespiration, . : 695 
Dumas on body temperature, 791 
>> * 9) legumin, : 51 
Baie milk, 130 
y> 9) Yespiration, . 735 
Dumeril on body temperature, 821 
Dunglison on gastric juice, . 352 
Duntze on body temperature, 815 


INDEX OF AUTHORS. 


PAGE 

Dupré on animal alkaloids, . 59 
Dupuy on skin secretion, » 1648 
Diiring on creatine, - aie 
Duroy ' on body temperature, 820, 821 
Dusing on respiration of embryo, . . 733 
Dutrochet on animal heat, z CE: 
Fe ;, osmosis, . 273, 284, 287 

Gs ;, plant temperatures, . 849 
Duval on salivary secretion, . : 513 
me ar on body temperature, 867 
,, hemoglobin, 2 = Gr 

Dyer on proteolytic ferments, 51 
EBERLE on gastric juice, 402 
Ss ;, intestinal emulsion, 447 
Eberth on wandering cells, . . 450 
Ebstein on digestive extracts, 324, 542 
5 57) astHc lands: 532, 534 

‘5 », pentoses, = : 3, 612 

an 55 pepsin, : , erpS L 

a >) ptyalin wee ‘ d 4, 1829 
Eck on removal of liver, - 908 
Kckerlein on respiration, 747, 752 
Eckhard on diabetes, 926, 927 
a ;, diabetic puncture, . 660 

st ;, filtration, . : : »» 281 

3 », glycogen, . . Shy 

5 ;, milk secretion, . . 663 

+ ,, renal secretion, . 645, 646 


>] 29 


salivary secretion, 328, 342, 343, 


484, 489, 495, 502, 503, 


504, 506, 509, 523 

AG ty 855 nerves, : 482 

;, Sweat nerves, 677 

Edelberg on intravascular coagulation, . is 
Edenhuizen on skin varnishing, 727 
Edkins on absorption, 432 
y> 5, coagulation of milk, 137 

es ees gastric secretion, . 531 

ss» 3, Metacasein, . 127 

5 ls Liss pancreatic extracts, «i niob2 

»» pepsin, . : 332, 543 
Edmunds on casein, 137 
i » milk coagulation, 134, 135 

Rs ‘ thyroidectomy, 940 

55 ;, urates, 42 
Edoux on body temperature, - 812 
Edwards on asphyxia, . 743, 745, 746 
= , body temperature, 793, 803, 804, 
813, 822, 846, 865 

ad ,, heat regulation, 2 8D2 

F ;, hibernation, 794, 796 

a ,, phosphorescence, : =») 1.480 

3 ,, respiration, 705 (2sannen 

af of hydrogen, 739 

Ehrenthal on intestinal secretion, 556 
Ehrlich on glycogen of blood, 158 
Eichberg on skin absorption, 685 
Eichholz on bile pigments, 338 
55 », chromogen of urobilin, 623 
Eichhorst on glycosuria, : 881 
55 ,, proteid absorption, 436 

5; succus entericus, 398 

Eichw ald on mucins. ¥ : 62 
> pus- -cells, . : : » see 

Eijkman on body temperature, 812 
Einhof on legumin, lenge 
y. Eiselsberg on thyroid grafting, . 942 
,, thyroidectomy, . 9Be 

Ekunina on lactic acid, ; 2 . 108 


ae a 


INDEX OF AUTHORS. 


PAGE 

Ellenberger on bile, . : . 869 
a “A body temperature, . 803, 805, 
807, 810 

_ », gastric digestion, . $4306 

5 », proteolytic ferments, . 51 

ia », Salivary secretion,. 489, 491 


,, sulphocyanate of saliva,. 345 
Ellinger on lymph, : : . Sls 


Ellis on body temperature, . : . 814 
Ely on ptyalin, . : : : 5 eee) 
iy 5, Saliva, i : 2 . 344 
Emich on taurocholic acid, : : . 392 
Emmerling on proteids, : : cg 
Emmert on fortal respiration, : 2 fol 
Emmet on gastric juice, é . 352 
Emminghaus on lymph-pr' oduction, - 289 
Engel on proteid quotient, . : =f 162 
Engelmann on electrical currents, . 682 
ap 5, electro-osmose, j . 688 

,, skin glands, . ‘ . 681 

y. Enschut on blood : gases, . ‘ ao 
Erb on body temperature, : . cor 
Erlenmeyer on tyrosin, ; 29, 423, 425 
Erler on respiratory exchange, . s (Abt 
Erlich on bilirubin, =. : . 3884 
Pees ioternal. ‘respiration, : 5 sr 
Erman on respiration, . ; . 704, 730 
Errara on glycogen, . : 5 oD 
Escombe on chitin, : ‘ : 6 es 
Estor on blood gases, . : - 5 
Etzinger on collagen, . ‘ ‘ . 428 
meneeeeclastin, . ‘ ee 29400 
Eulenberg on animal heat, . : . 863 
Eves on ptyalin, . j aia29 
Ewald on bacterial digestion, . . 464 
Pe Gtles | : ; . 9869 

Ai ee blood gases, 761, 762, 763, 765 
Pps collagen: 2 : : . 430 
P45 clastin, : ‘ ; ote 

»» >, fatabsorption, . “ - 452 
peo ASLIIC digestion, ‘ . 9849, 356 
tare internal Tesniranion, : . 783 

oe 55, muscle, : F Fh Ge 
Pees eur oker atin, ; é orn eae 
pees, Wleuritic finid, «. ; . 784 

+> >», proteid absorption, : SZ BY) 

53) 99) SUCCUS entericus, . . a et) 
Semiay roid extract, . < A . 943 

»» >, thyroidectomy, . . 939, 940 

, trypsin, : - . 388, 552 

Ewart on rigor mortis, : : >. 
Exner on diffusion, ; ; : 5) CTE 
Eyckmann on blood, , : . . 149 
Eylert on marrow, : c : 5) aly) 


FAHRENHEIT on body temperature, . 815 


Falck on skin absorption, . : . 685 
Falk on gastric juice, . : : . 364 
LS a ptyalin, : 5 - 329 
Fano on albumose in blood, : . 439 
»» », coagulation, . ; ae a7, 
Favre on heat of combustion, . 833, 834 
Pe SWEAL,. 670, 671, 672 
Fawcett on body temperature, 821, 858 
3, gout, . : . c - 596 
Fawlitsky on gastric juice, . : . 866 
Fayrer on snake venom, : : 5 we 
Feder on ammonia in urine, ’ ‘ 5 hy 
s, 5, metabolism, . : . 894 


Fehling on body temperature, . . 804 


1007 
PAGE 

Fehling on dextrose, . : : Fe itt) 
»» >, Salivary glands, . 524, 930 
Fehr on salivary glands, “ 524, 930 
Fenwick on sulphocyanate of saliva, . 846 
Fermi on trypsin, : . 430 
Fernet on blood gases, . 758, 766, 769, 772 
Ferrier on body temperature, - . 864 
Fick on body temperature, . : . 867 
>, >» diffusion, ‘ j ; 7262 
mies endosmotic equivalent, : 3 p2re 
ee. OSMOSIS) Mis é : ; 27D 
se DCRSUDsi a F . 404 

5) 9, proteid metabolism, F . 912 

,, red corpuscles, . : 4 epelod 
Field on sweat secretion, . : . 680 
Filehne on diabetes, . 4° 927 
Fillipi on digestion and absorption, - 442 
Finkler on blood- -gases, ‘ - 163, 765 
so. oanloodiy: temperature, - 1905792 

as ,, internal respiration, . 781 


+> 5) respiration, 699, 700, 701, 707, 


711, 756, 780, 848 


Finlayson on body temperature, . . 804 
Fischer on animal heat, F 5 A) colts} 
»> 4, carbohydrates, . ; : 2 
»> 5», dextrose in urine, j . 608 
»> 9, formose, - : : : 5 
> 9» gelatin, 38, JL 
»» '», glycuronic acid, 5 
Fp nisomaltosesss ‘ : ate. 
1. samlysine; 3 : é . 426 
»> 9) Mannose, : ; é 7 
35), 55) OSMOSIS! ; 2 : we 27T3 
5 - 9) Sugars, : Os Oooo 
Fe legs xanthine, i F ‘ . 996 
Fitz on pus, . : : : , Bots! 
Flaum on pepsin, . : : P . ddl 
Fleischer on milk, j ; 5 AK) 
s ,, Skin absorption, 685, 686, 687, 
689, 690 
v. Fleischl on hemoglobin, .—. » 152 
Fleischmann on colostrum, . : enli29 
i pean ke 125, 180 
Flensburg on urine, .. : ‘ . 603 
Fletcher on muscle, F 911, 912 
ss », proteids, . = is) 

Ff », Saliva, 344, 494, 499, 500, 504, 
509, 510 
Fleury on body temperature, : . 818 
Flint on gases of alimentary canal, . 730 
»> 3) muscular metabolism, . + 93 
Floresco on peptone plasma, . - 175 
Foa on intravascular coagulation, . 5 alzfe} 
»> >», suprarenal body, : : 90, 950 
Fodera on pancreatic fistula, : . 3866 
Feettinger on fish slime, ; - POLS 
Fohmann onlymph, . : : . 287 
Fohringer on body temperature, . 790, 805 
Fokker on lime in food, ; : . 886 
»» 9) TFespiration of CO, ; . 740 
Fontana on respiration of hydrogen, . 739 
» 5, Snake venom, . ‘ ay kts 
ea trl ene. OE : ; . 7148 
Forbes on body heat, . : ; - 850 
Fordos on pus, . : 3 . 84 
Fordyce on teinperature, 3 : . 814 
Forlanini on skin absorption, ; . 689 
Fornara on skin secretion, . : 3. 673 
Forrest on marrow cells, , : 4, 84 


Forster on lime in food, ‘ : . 886 


1008 
PAGE 
Forster on proteid food, 878 
3> 9) proteid metabolism, 897 
3) >) Tespiration, . 696 
> 9», Salts of food, 883 
Fortunatow on fat absorption, 450 
Foster on fat absorption, 462 
»> 9», glycogenesis, 925 
»> 9, heart work, 842 
Pe gee proteid digestion, 438 
», rennin, A 134 
Fourcault on skin var nishing, 727 
Fracassati on respiration, : - 692 
Framm on caramel, : ‘ : : 7 
»> 9s Moore’s test, : 7 
ES Franck on pancreatic secr ‘etion, 550 
»» Sweat, 671 
Frank on fat absorption, 462 
>> 9) gastric juice, . 364 
Frankel on blood, 150 
», carnic acid, 104 
53 »» glycogen, 15 
ae », losinic acid, = 103 
o 5, respiration, 707, 718, 788 
xn », suprarenal body, ‘ leg 
, thyroid body, 88, 89 
Frankland on ‘heat of combustion, 834, 838, 
874 
35 », milk, + sei 
Franklin on animal heat, 818, 851, 858 
Fraser on snake poison, 5 56 
Frassineto on fractional coagulation, 43 
is 5, proteid- -quotient, 162 
Fredericq on animal heat, 864 
of », blood gases, 778 
= », fractional coagulation, 43 
5 ,, hemocyanin, 1 aG' 
es », Tespiration, 699, 711, 718, 719, 
721, 776, 803 
,, tension of gases, 784 
Frederikse on fibrin, 167 
Fremont on gastric juice, 349 
Frémy on cartilage, 114 
»>  »3 fossil bones, 111 
re meelaims 70 
Shee; ichithins 52 
Frentzal on muscular metabolism, 916 
Frerichs on bile, 371 
a hae pigments, 389 
55 salieri 86 
35 >, Pamereas, . 92 
ee », Saliva, 348 
a », Spinal injury, 861 
5 5, Spleen, 87 
“3 >, Succus entericus, 369 
6 ,, thymus, 88 
55 ,, thyroid, 88 
D ,, torpedo organ, 111 
;, urea in muscle, . 102 
Freudberg on alkalinity of blood, . 144 
Freund on acidity of urine, : 577 
»> 955 animal gum, : lds 
+> 5, coagulation, 167, 169, 175 
v. Frey on CO, of muscle, ; oe OL? 
s> », emulsion, 445, 447 
»> >, gases of blood, G3 
»> 3) lactic acid in blood, . 905 
>> 5, respiratory exchange, . . 841 
5» » Salivary secretion, 505, 506 
>> », Sarcolactic acid, . ; es LOG 
», >, temperature of blood, 896 


INDEX OF AUTHORS. 


PAGE 

Freytag on cerebrins, < 2 abaG 
3 », protagon, 118 
Friedberg on rennet, 134 
Friedlander on respiratory exchange, 694 
Friedrich on amyloid substance, at sae 
», caisson disease, Af Woh 

Friend on aqueous humour, : 122, 182 
,, red corpuscles, 155 


Frohlich on body temperature, 789, 799, 802, 


820, 821 

Fubini on cutaneous respiration, 723, 726, 
727 

- 5, Yrespiratory eee : 722 
$5 » Saliva, . 3848 

a », skin absorption, . 686, 687, 689 
530 go Sectetlonseae ilocial 

Funke on blood crystals, 208, 205, 206, 208 
»> 9) hemoglobin, 194 
i ae intestinal secretion, 556 

> 5, imtraglobular crystallisation, 191 

. - sweat, : 672 
Furnell on body temperature, 813 
y. Fiirth on lactic acid, : 109 
5 », muscle plasma, : 98 
Fusari on salivary nerves, 525 
GABRIEL on amido-acids, . 880 
5 », bone, : 112, 113 

$5 ,, eggalbumin, . ; eae 

,, tooth, f 112 
Gabritschew sky on glycogen ‘of blood, 158 
Gad on emulsion, : 445, 446 


sos Lesidual ainseeue i : 750 
Gaertner on hematocrit, ; 148, 
Gaglio on lactic acid in blood, 159, 160, 

6p Oxalates ini toodomr - 61 


»> 5, respiration of CO, 740, 741 
55 », sarcolactic acid, . 106 
Galen on animal heat, . 832 
»> 5, cutaneous respiration, 725 


»> 5, on functions of skin, . 2d 


Galeotti on secretory cells, 938 
Galileo on thermometer, 785 
Galloise on inosit, 606 
Gamgee on acid of gastric juice, 355, 363, 365 
s> 5; amido-acids, ; : 421 

a ,, bile, 390 
Pe eiblood corpuscles, . a8 

Fe ep Ocul ain : : = « 4 

3 5 coagulation, 168 

3 ,, coefficient of distribution, 354, 
355 

ss 3, CO-hemoglobin, . . 288, 240 

« 5, feces, 3 5 » Pars 

5) “Pay gmgas analysis, : 5) ki) 

of a ese DULL are : : Hom (Hl) 

Af 5, gastric juice, : 349 

AS », hematin, 254 

53 », hemochromogen, 2B 

43 », hemoglobin, : 185, 187 

jo indoles 2 5 - 468 
eyed intestinal fistule, 368 

5 ,», lysine and lysatine, 427 


methemoglobin, . "945, 246, me 


+> 9) Pancreatic extracts, ay 
at ose phenoll . . AGT 
» 9; protagon, . : 118, 119, 120 
»  »)_ proteids, 24 


salivary secretion, - . 525 


INDEX OF AUTHORS. 


PAGE 

Gamgee on Soret’s band, . 226 
+> 9) Succus entericus, 555, 556 

Ss », sulphocyanate of saliva, 504 

Be », tryptic digestion, 421, 552 

», turacin, 3 61 

Gara on thyroid feeding, 944 
Garland on succus enteri icus, 398 
Garrod on bile pigments, 388 
os ,, blood plasma, 160 
24 ,, red corpuscles, 152 


587, 596, 909 
260, 619, 620, 


uric acid, - 
urinary pigments, 


2) > 
22 Pel 


623, 624, 625 

os », urobilin, 621, 622, 629 
», urorosein, - 628 
Garvoch on bile pigments, 388 
Gaskell on lymphatics, 300 
3,59, Metabolism, 869 

>’) °»; ervous system, . 184 

%, 9, salivary nerves, 482 
Gassot on body temperature, 825 
Gaule on lymph gases, . 783 


Gautier on alkaloids in urine, : ; 
», animal alkaloids, . 59, 60, 61 


39 


Paes tab 1ormation, : . 933 

+> 3, leucomaines, 101 

», Snake-venom, . 56 
Gavarret on body heat, 791, 793, 796, 832, 
846 

5 », effects of cold, . 3 . 818 

a », respiratory exchange, 698, 722 

ee ,, temperature of plants, . 849 
Gaymard on effects of cold, . 4 NSLS 
y. Gehlen on legumin, . 51 
Geigel on skin temperature, . 829 
Generale on parathyroids, 940 
Genersich on lymph-flow, 300 
Genser on milk, : 127 
Geoghegan on brain, 116 
Ac ;, cerebrin, 120 

53 », nuclein, 65 
Georgiewsky on thyroidectomy, . 944 
Geppert on blood, : seey 44,150 
Pou, ~ 54. Gases, 715, 761, 762, 772 

+» >, body temperature, . 820 

» 99 gas analysis, . 760 

s» 5) Tespiration, 699, 708, 714, 718, 
728, 747 

Gerber on milk, : 128 
Gerlach on cutaneous respiration, . 726, 727 
ee as gastric juice, 361 

5 ;, respiration of embryo, | . (33 

- ,, Skin-varnishing, . 727, 728 
Giacosa on mucinogen, . : pn 62 
Gianuzzi on salivary glands, . 511 
Gibson on chitin, . ‘ ea 
Gierse on animal heat, . 789, 799 
Gies on tendon, : 5S Wy 
Gilbert on fats, 931, 932, 934 
Gildemeister on respiratory exchange, a! 
Giles on boay temperature, 812 
Gilson on choline, : yee 
Ginsberg on glycosuria, 609, 881 
Girard on body temperature, . 863 
Girgensohn on proteids, 40 


772 
213 


Girtanner on blood gases, 


757, 762, 
Gladstone on spectrum, - ; 


Glaser on body temperature, 822 
Gleiss on acidity of muscle, 108 
Gley on body temperature, 789, 801, 808 


VOL. I.—64 


1009 

PAGE 

Gley on coagulation, 174, 178 
yal, 55 .Giabetes: '. 928 
3» 95 Lacteals, 302 
»> ») parathyroids, 940 
+> 5 Salivary secretion, 514 
»» 9» thyroid extract, : 943 
»» 9, thyroidectomy, 939, 940, 941, 942, 
943 

Gluge on skin-varnishing, 127 
Gluzinski on thyroid feeding, 944 
Gmelin on absorption, . 431 
Bee 33)2Dile; ole 

; +» »» pigments, 382, 385, 629 

Ee 5, blood gases, ; 3 = 7iste 

= ,, gastric juice, . 352, 536, 540 

a » gelatin, : . 430 

5) 34 leucine: 29, 422 

‘ », lymph ‘absorption, «143038 

ay ., pancreatic secretion, . 3868 

- .; proteids, af 2h 

; ,», saliva, 345, 348 

Ss ,, taurine, ono 

., tryptophan, 427 

Gnezda on biuret reaction, 48 
Gobley on lecithin, 21 
Godfrin on body temperature, : 820 
Goebeb on proteolytic secretions, . 330 
Goldfuss on blood plasma, 160 
Golding-Bird on purpurin, 623 
Goldmann on cystine, : 603 
,, sulphur of urine, 632 
Goldschmidt on digestion, 356 
> », ptyalin, 327 
Goldstein on heat reeuae 856 
Goll on urine, 645 
Goltz on nerves of stomach, 538 
ss 3; Sweat secretion, 676 
Gonnermann on gelatin, 71 


867 


Goodhart on body temperature, 
751 


Goodwyn on respiration, 748, 750, 
Gordon on cutaneous respiration, . 

:, », heat regulation, . 3 . 735 
», respiratory exchange, . 


3? é 
;, temperature of embryo, 850, 


23 


Gorup-Besanez on aqueous humour, 183 
ry »» bile, : 371 

” ” fats, 17 

5 ;, milk, 129 

- », muscle, 95 

np oe proteids, : 24 

. 5, proteolytic ferments, 51 

E », Spleen, : 7 Of 

; ,, thymus, . 87 

, thyroid, . 88 

Gottlieb on pancreatic secretion, 549, 551 
Ae », suprarenal extract, a= 951 

», thyro-iodin, 89 
Gottwalt on filtration, . 280, 282, 283 
Ps », kidney tissue, 92 
Gourfein on suprarenals, 949 
Gourlay on peptone in spleen, 5 Be 
- 5, proteids, < ‘ . 41, 87, 89 
Gow on pancreatic casein, A a aleyi 
BR is ae extracts, . . 336 
Gowers on hemoglobin, : = Jey Ibe 
de Graaf on pancreatic fistula, 366 
Graham on diffusion, 43, 262, 263, 284, 361 
Graham-Lusk on proteid food, 876 
Grandis on respiratory exchange, : 717 
Graser on bacteria of urine, . 583 


IOIO 
PAGE 
Gratiolet on skin secretions, 673 
5, Suprarenals, . 948 
Griwitz on blood, . 143, 150 
+ 3 mountain sickness, 738 
Green on coagulation of blood, 169 
9 23 29 ) milk, - 135 
>> 5; ferments, i yl 5) 
rs hs euibrins 167 
3. 3) Deossin, 63 
3 vegetable albumin, : 51 
Gréhant on ‘blood, 141, 142, 160 
- ser tose mEASES, Re (G84) 
an ;, heart-work, : . 842 
. 5, respiration, 707, 717, 740, 741, 
749 
Greidenberg on sweat secretion, 679 
Gresswell on body temperature, 812 
Griess on nitrites of saliva 346 
Griessmayer on proteid digestion, 400 
,, starch digestion, . 395 
Griffiths on alkaloids in urine, 61 
5 ,, blood gases, 768 
Bs ;, neurochitin, 75 
,, reducing power of pr otoplasm, 39 
Grimaux on coagulation, 181 
$3 », Synthesis of proteids, 36 
Griswold on ptyalin, : 328 
Groger on bacterial digestion, 471 
Gréper on fat absorption, 461 
Groves on uric acid, 595 
Gruber on carbohydrate digestion, 394, 395, 
434 
j ,, CO, of muscle, 912 
: », gastric juice, 356 
- Be pty alin, 328 
ee respiration of Co, 740 
>» 9, Tespiratory exchange, : 717 
urine, . : 580 
Griibler on cr ystallised proteids, ey 
93 », molecular weight of proteids, 27 
- 3, vegetable proteids, 52 
Grundelach on taurocholic acid, . 376 
Griinhagen on aqueous humour, 122, 183 
a ,, digestive solutions, 324 
5, saliva, 525 
Grunzw eig on milk fat, 133 
Griitzner on diastasimetry, : 325 
as ,, digestive solutions, . 324 
; ,, gastric glands, . 532, 534 
% sah esse} 536, 544 
a ;, muscle, 2110 
a »> pepsin, 331, 542 
: »» pialyn, . 339 
i ,, proteolysis, 324 
o ,, renal secretion, . 654 
a ,; rennet ferment,. 544 
, ;, saliva, 327 
,, salivary secr etion, 484 
Gryns on isotony, 271 
, permeability ‘of cor puscles, 277 
Gscheidlen on blood, 141 
ie 53 hemoglobin, : 194 
x ;, lactic acid, 106 
ns », muscle, . : 110 
ns ;; hervous tissues, 117 
= re iitae tein of saliva, . 345 
33 , urine, 346 
Gubler on milk, 3 : e273 
Guinard on skin absorption, 687 
Gull on myxcedema, 938 


INDEX OF AUTHORS. 


PAGE 

Gulland on glycogen, . : « (92% 
Gumilewski on succus entericus, 369, 556 
Gumlich on ammonia in urine, > OD 
Be 5, caseinogen, 137 

35 ,, nucleo-proteids, 67 
Gunsberg on gastric juice, 365 
i », gluten, 53 
Giinther on animal heat, 862 
Giirber on crystalline albumin, 44, 163 
>> 5; oxidation in tissues, . 895 

Foe) gay KeSPlration,,. : 706, 781 

3) «135 thiyroid feeding, ; . 944 

3> 33 White blood corpuscles, ily 
Gusserow on fcetal respiration, 731 
Gyergyai on albumose in blood, 439 
as ;, proteid food, . 878 
HAAs on proteids, 46 
Habermann on aspartic acid, 29, 425 
i », glutaminic acid, tee, 426 

2 ;, levulose, . F ks 5 

a ,, leucine and tyrosine, 425 

5, proteids, , 34 

Hadden on myxcedema, 939 
», salivary secretion, 492 

Haddon on milk, 5 ‘ 126 
Hagemann on butter, : 133 
», respiration, . « (26, 729 

Hahn on caseinogen, 136 
3}. 55 LLVER . , 908 
bias pepsin, f 332, 333 


. 593, 598, 638 

768, 776, 778, 779 
. 844, 845 

696, 697, 698, 699, 
739, 740, 741, 742 
Hale on body temperature, . - 857 


Haig on uric acid, 

Haldane on blood gases, 
53 ,, calorimetry, 
se 5, Tespiration, 


Hales on body temperature, 786, 832 
+> 9 Tespiration, 6938, 741, 751 
Hall on hibernation, . : . 795, 796 
\, 55 sron in foods . 886 
Bie och) 79" 299 liver, 5 st a 86 
oy aoa eresidual aire ; f <apib0 
Haller on asphyxia, 745 
:> 93 blood heat, 827 
Bb. + 95, ChEyles 287 

Sst peal respiration, . : ; eo 
Hallervorden on ammonia in urine, . 907 
», saltsin food, . . 883 

Halley on thermometer, - 785 
Halliburton on aqueous humour,. 122, 182 
3s ;, artificial colloids,. 173, 177, 

181 

; ;, blood of invertebrates, . 186, 

768 


cell globulin, 82, 156, 188 
cellulose, . 3 
cerebro-spinal fluid, 

chemical constituents of 


body, : - « > ssf) amelaiaal 


., chitin, . 74 
; ca coagulation, . 109, 173, 177 
» »» gas pump, 75 
35 PP hemocyanin, 61 
He ,, hemoglobin, 204 
a ,, lactic acid, ‘ 109 
; :, lactoglobulin, y fetes 
a ;, Muscle serum, 96 
<5 ;, myohematin, : ~ e909 
i 5, myxcedema, . 939 


INDEX OF AUTHORS. 


PAGE 

Halliburton on nervous tissues, 117, 118 
an ,, nucleo-proteids, 68, 81, 83, 84, 

155, 170, 181 

“3 »» pancreatic casein, . 4 iBi/ 

sy a * extracts, - 900 

a », paramyosinogen, 97, 98 

¥ ,, pericardial fluid, ~ 183 

e 5, proteids, 41, 42, 43, 86, 118, 


122, 161, 162, 872 
of plasma, 161, 162, 
163, 165, 166, 167 


92 ? 2 


a », pyrocatechin, 4 606 
a ,, renal tissue, : 3. m9Z 
a ;; Schmidt’s extract, 170, 171 
a5 55 secretions, ; . 183 
e ;, sulphates in tissues, cml 
- ,, tetronerythrin, . eee! 
- i thyroidectomy, j = 941 

xanthine in plasma, . 160 


Hallmann on ‘body temperature, . 789, 799 
Halstead on thyroid grafting, . ee 


Hambly on cutaneous respiration, G20 
Hamburger on absorption, . . 304, 307 
% ;, blood, . : ORAS, 
M5 », diastatic ferment of 
blood, : 5 GY, 
ee », isotony, ; oh gp L422 (i 
a ,, saltsoflymph, . - 286 
», succus entericus, . +, 398 
Hammarbacher on OU pe ae a . 664 
es saliva, 5 : 348 
Hammarsten on Adamkiewicz’s reaction, 47 
n3 3, ascitic fluid, é aerg Oe 
om 5 Ee 85, 370, 378, 374 
ay ;; bilirubin, . % - ood 
As ,, blood gases, 762, 770 
a wise eptoteids, . 1625 165 
ie »» casein, - é sy; 
on », caseinogen, 4 ~. ASG 
a 5, cholalic acid, . 381 
“s ,, coagulation of blood, . 168, 
: 171 
re 5, enzymes, . 5 a ely 
A 5, feces, ; é . 473 
ve ;, fibrin, j 167 
3 ,, fibrinogen, . 164, 170, 172 
- 3, gastric juice, 350, 363 
95 ;, gelatin, é . 2 180 
i ,, hematoporphyrin, . 625 
43 », hemochromogen, 7 206 
a », helico-proteid, . . 64 
sp 5, LENA : Seis 
Ba ,, lactic acid, . : . 109 
5s », lymph gases, _ . S783 
a3 », mammary gland, - 124 
a eal).  gonwd29) 135, 334 
Hs ;, mucin, : : = 62: 
55 5, mucinogen, 5 OZ 
ee ;, Mucoids, . : Oe 
e ;, musculin, . ; surah 
ms ;, nucleo-proteids, . 3, 64, 67 
3 », oxalate plasma, . Go 
Me », pancreatic extracts, . 337 
x, 5 pepsin, 330, 331 
as ;» precipitation of pro- 
teids, 5 . 9392 
i RS proteids, 42, 49 
f », prothrombin, 175, 179 
: op Seino, 329 
S53 », rennet, 134, 335, 543 


IOI! 

PAGE 

Hammarsten on rennin, 334, 335, 544 
- », saliva, , 3 3 92 

oe », Salivary cells, . Beer /¢/ 

= », Skeletins, . ; Pee As 

y », Synovia, . t . 184 
vitellin, . - 5 EL, 


Hammerschlag on blood, 
Hankin on coagulation, . : A G7 
Hannover on respiratory exchange, . 781 
Hanriot on diastatic ferment of blood,. 160 
* ,, gases of alimentary canal, . 730 

re », respiratory exchange, . 699, 708, 
714, 716, 717, 718, 

756, 916, 933 


5 », Spirometer, 752 
Hansen on proteolytic fer ments, . oe hoe 
Hardy on succus entericus, . : . 554 

S  asgumbuce corpuscles, = ; 3 152 
Harley on diabetes, : . 928, 929 

»» 5, fat absorption, . i ebvtes 49 

bs, 99 SLY COSUTIA yn - 5 efsirl 

»  »; lactic acid in blood, ; - 160 

ay | op mouScular metabolism, . 9) US) 

as es meachionh. of intestinal con- 
tents, a ; . 452, 453 
»> 9) sugarin blood, . : Gil 
;, Suprarenals, . : : . 948 
Harnack on ash-free albumin, . a) BE 

35 ,, formula of albumin, : ZO 

¥ ;, muscarine . : : 5 

a >, Sweat, 5 5 5 A yAl 
Harris on casein, . : ; . By aley7/ 

a5 ee hematin, 3 : 7 200 

> >, intestinal bacteria, : yao 

+ tik milk, 125, 126, 135 

Bo igs pancreatic casein, - 5) ley 

a 55 5 extracts; .. . 336 

», reducing power of sugars, . a 
Harrison on spleen, : : : - 959 
Hart on elastin, 71, 72, 430 
Hartig on vegetable pr oteid, ; 5 
Hartmann on wool- fat, ‘ - . 675 
Harvey on asphyxia, . : - . 145 

»> 9 Tespiration, . : : Sale 
Harzer on osmosis, ; ». wz 
Hasebroéck on bacterial digestion, . 1) G2, 


” ” fibrin, . . . A aly/ 
lecithin, ; ; . 463 


22 2? 


is », proteid digestion, . . 405 
Hasse on pigeons’ milk, . : . 676 
Hassenfratz on blood gases, . : 5 GDL 

33 », heat production, . . 839 
Hastings on animal heat, . 857, 858 
Haubner on cellulose, . - : . 470 
Hauff on milk, . : : a Y/ 
Hausmann on ‘acidity of urine, . 578, 580 
Haycraft on bile pigments, . 5 . 383 

3 », coagulation, 42, 43, 147, 169 

Re », glycogen,. : a) OLY, 

Bp », levulose, . F ; 7, (Gu 

;, reaction of blood, . . 144 

Hayem on blood, . : : 7 50 
Rae, se doetall ‘respiration, : . 732 
Heckel on cholesterin, . é : |, 24 
eo. 5, lLecithinsees . 7 5 weal 
Hedenius on keratin, . ; é PS 
Hedin on blood, . ° 142, 148, 149 
+ ~~, Coagulation, . c - lic 

@ .) by gelatin,. : ; : » ge 

A * 5) liseInacocrits.. ; : 5 yi 


1012 


Hedin on keratin, 


be) 
99 


a) 


INDEX OF AUTHORS. 


PAGE 

73 

,», lysine and lysatine, 33, 426, 427 

,, testis, : 5 SB 
Hédon on biliary fistula, . 460 
;, diabetes, 928, 929 

3» tab absorption, . 460 


9 


Hetfter on fatty acids of liver, 
Heidenhain on absorption, 


39 


- 


vw 
vw 


. 936 
284, 432, 433, 
441, 458, 461, 462 


bile, . ‘ 560, 565 
blood gases, . 772 
coagulation, . 147 
dialysis, 321 
gastric fistula, 537 
», glands, 532 
», secretion, . 363, 538, 
539, 540, 541 
heat formation in nerve, 808 
intestinal emulsion, 448 
AD secretion, 555 
Jacobson’s nerve, . 483 
lactic acid, 108 
lymph, : 181 
5» production, 289, 290, 
291, 292, 293, 295, 297, 
298, 310 
milk, 140, 663, 664 
», secretion, 666, 667 
paralytic secretion, 519, 521, 
522 
pancreatic cells, . . 546 
5 fistula, 366 
ne secretion, 368, 547, 
548, 549, 
551, 553 
parotid saliva, 508 
pepsin, : . 331 
pyloric secretion, - 532, 534, 
535 

reaction of nervous 
tissues, ; d itil7/ 
salivary cells, ahi, 
55 nerves, 482, 483 
= secretion, 343, 344, 


485, 486, 487, 495, 496, 

498, 499, 500, 503, 507, 

508, 509, 510, 511, 513, 

514, 515, 520, 525, 527 

salts of saliva, . . 494 
secretion of urine, 647, 648, 
650, 652, 653, 654, 

656, 658, 661 

secretory nerves, . . 526 
submaxillary gland, 516, 843 


aA ,, temperature of blood, . 829 

3 ,, tetanus, 0 LING) 

,», trypsin, 338, 552 

Heine on microchemical methods, 66 
Heintz on amphoteric reaction, 577 
so) os) Duliphaim: 382 

»> 99 biliverdin, 385 

Aes One. 77 

30 as chenocholic acid, . 377 

a5 #55. LUSCIner 121 
ty eaulllis coagulation, 334 

» 9 fat, 133 

Heller on caisson disease, 737 
»> »5 lymph flow, 302 
i 4. curine: 605, 611, 629 
39 9, Uroerythrin, . : 3 - 623 


Hellier on discharge of milk, 
Helm on gastric fistula, 
Helmholtz on calorimetry, 


te) 99 gas pulp, 
2 », heat loss, 


2? be) +P) 


value, 


9 ” 


», muscle, i 
Van Helmont on digestion, : 
v. Heltzl on enzymes, . 
Hemala on tryptophan, 
Hempel on caseinogen, 
», gas analysis, 
es gee 

oe) 9 milk, 

Henle on lymph, . 
Henneberg on fat formation, 
$s », respiration, 
Henninger on peptones, 
Hénocque on hemoglobin, 
Henriques on jecorin, 
9 ,, lungs, 
Hensen on glycogen, 

»» _ os lymph, . 
Henschen on renal secretion, 
Hergenhahn on glycogen, 
Hering on blood gases, 
oe ” heat, © 
;, metabolism, 

A ,, salivary secretion, 
Herissant on foetal respiration, 
l’Heritier on milk, ‘ 
Hermann on bile secretion, . 


bo] 


be) 
> 


99 
9? 


feeces, 

fibrin, 

gastric fistula, . 2 

hzemoscope, 

heat production, 
», value, 

inogen, 


lecithin, 

M3 », muscle, 

NO in blood, 
proteids, . : 
proteid digestion, 
red cor puscles, . 
renal circulation, 
residual air, 


skin absorption, 
», glands, 
sweat, 
tryptic digestion, 
5 , vital capacity, i 
Hermans on respiration, 
Hermite on diffusion, . 


2? 39 


Heron on carbohydrate absorption, 


»» enzymes, 
,, fat absorption, 

,» ptyalin, : 
,, starch digestion, . 
5» succus entericus, 
Herringham on uric acid, 
Herroun on bile, . 

Herschel on spectrum, 
Herter on blood gases, . 


production, 


electrical currents, . 


internal respiration, . 
intestinal secretion, . 


secretion of urine, 


PAGE 


808, 


827, 868, 


682, 683, 


749, 750, 
646, 


673, 


517, 519, 


668 
537 
846 
759 
850 
833 
838 
110 
401 
314 
428 
139 
760 
759 
128 
287 
934 
718 
400 
231 
160 
757 


, 922 
» 783 


654 
918 
761 
828 
870 
529 
731 
128 
567 


684 
473 
167 
537 
210 
841 
834 
110 
782 
556 

21 
911 
241 

46 
405 
189 
642 
752 
650 
688 
683 
671 
416 


, 752 


742 
275 
435 
399 
452 
328 
397 
398 
595 
371 
208 
777 


INDEX OF AUTHORS. 


Herter on pancreatic secretion, 
s> 99 Yespiratory exchange, 
aes, salivas.; 
Herth on proteid digestion, . . 
Hertwig on body temperature, 
Herz on animal amyloid, 
Herzen on gastric juice, 
Herzfeld on maltodextrin, . 
Herzog on respiratory exchange, 
», ;, Skin absorption, . 
Hess on heat production, 
Hesse on cholesterin, 
32 9) expired air, 
aA; lactose, . : : 
Hester on uric acid, 
Hewlett on fractional coagulation, 
op ,, lactoglobulin, A 
Hewson on blood, 
ch yle, : 
Bauer lshlp lymph, 
coagulation, 
lymphatics, 
», red corpuscles, 
Heynsius on ash-free albumin, 
s ps Dile::. : 
63 3 bilicyanin, 
Higgins on respiration, = ; 
Hill on blood gases, 761, 763, 


cerebral circulation, . 
as pump, 
+> 3, hibernation, 
muscle, 
respiratory exchange, 
salivary glands, 
Hillersohn on specific heat, 
Hinterberger on excretin, 
Hippocrates on skin absorption, 
Hirn on calorimetry, - 
ss >, heat production, 

Hirschberger on mannose, 
Hirschfeld on diet, 

- - fuscin, 

4 », muscular metabolism, 

;, uric acid, 

Hirschler on lymphatic glands, 

2? 2) spleen, 

re », tryptic digestion, 
Hirschmann on blood gases, 
His on cornea, ; 
Hitzig on body heat, 
Hjort on vegetable ferments, 
Hlasiwetz on aspartic acid, 


Ae », glutaminic acid, 
93 ,», leucine and tyrosine, 
ss ;, levulose, 


He proteids, $ 
Hobday on body temperature, 


PAGE 


347, 


764, 


body temperature, 808, 826, 830, 


841, 


517, 843, 


838, 


761, 


29, 
32, 


368 
694 
348 
400 
816 
133 
349 
396 
848 
688 
834 


= 0 
32, 34 


790, 791, 792, 


Hochhaus on iron in ‘liver, : F 
Hoesslin on respiration, 


803, 805, 807, 812, 821, 826 
‘ 86 
720, 732 


van t’Hoff on osmosis, 265, 266, 284, 650, 651 


Be 35 stereochemical isomerides, 106 

Hoffa on thyroidectomy, ; 939 
Hofiemann on creatin in urine, 598 
Hoffmann on body temperature, 806 
ms », eudosmotic equivalent, 274 

.. ,, hippuric acid, . 893 

., », liver fat, . 936 

¥ ,, proteid quotient, 162 


1013 

PAGE 

Hoffmann on proteids, . 3 Atel 

Re ,, skin absorption, : . 688 

i ,, Sugar formation, om 9 

55 ,, tyrosine, . = . 424 

Hoffmann-Wellenhof on respiration, . 742 

Hofmann on bile secretion, . . 560 

ss ;, fat formation, . 933 

a », gases of alimentary canal, 729 

Fe m3 lymph, : . 182 

x sweat, a Gite 

Hofmeier on uric acid, SE 

Hofmeister on adsorption, 276 

a5 ;, albumin crystals, 43 

+3 ,, albumose in blood, 439 

a ;; assimilation, . 900 

ys », bile, 369 

fi. ,, collagen, 70 

ne ;, colloids, 42 

x ;, digestion, 471 

re >, enzymes, - - 316 

AR », gastric absorption, . 432 

Pe a ;, digestion, 356 

5 ,, gelatin, - 430 

a if a peptones, are eG 

vs », glycosuria, 5 tehol! 

e », lactose, . » W2 

- aay esses deni; 611, 665 

5 3; peptones, . 400 

2, ;, pituitary body, . 946 

es ,, proteid absorption, 439, 440, 

441 

$3 ;, proteids, : 32 

5 5, proteolytic ferments, 51 

2. »> pus cells, 83 

ze ;, salivary secretion, 343, 347, 

489, 491 

Ar 5; Starch - + 1a 

3 Be sulphocyanate of saliva,. 345 

,, thyroidectomy, . . 940 

Hizyes on sweat secretion, 679, 680 

Holloway on thermometer, » $85 

Holm on suprarenals, = 90 

Holmgren on blood gases, _. 765, 779 

», gastric fistula, . 537 

Holzmann on fibrin, . . ily, 

Home on fcetal respiration, . . 733 

Hook on respiration, . 692 

ais ath thermometer, 4 ethics 

Hooper on body temperature, 789, 799 

Hopkins on pigments of feces, . . 0388 

6 »» precipitation by neutral 

salts, 42 

53 », uric acid, 592 

3 3, urine, : 5 By) 

5 », urobilin, 621, 622, 629 

;, urorosein, . = Be 
Hoppe-Seyler on adi yocere, 2 

PP Pi : = cdccital - 882 

3 ,, aqueous humour, 183 

i ,, arterin and phlebin, 190, 


191, 192, 193, 196 


370, 374, 376, 389, 


390, 560, 562, 566 ° 


i) 22 bile, 
=f ;; blood, 147, 
a) aes corpuscles, 
2? 33 >? crystals, 
3? 3? 23 gases, 
3 At spectrum, . 
29 


body temperature, 


148, 


203, 
766, 


790, 


160 


147, 155, 


156 
208 
772 
208 
820 


IOI4 


Hoppe-Seyler on bone, 


3) 


Hor baczew ski on elastin, 


33 
23 
33 


3? 


39 


. 


39 


2) 


33 


33 


INDEX OF AUTHORS. 


PAGE 

° 111, 112 

burns, , - 728 
cartilage, . 5 = 13 
casein, : Z iy 125 
cellulose, . : PRAT A. 
cerebrins, . : ce ala hy 
chitosan, . ; By eel ta 
cholesterin, = 159; 591 
chyle, : . 1838 
CO in blood, 237, 240 
collagen, . : oe fh!) 
creatinine . - SiO 
erystallin, . - - 128 
diabetes, . : 927 
digestion of cane sugar, 398 
enamel, ¢ 112 
excretion of lime salts, 635 
fat absorption, . . 452 
fats of blood, . * 59 
filtration, . : ~ 282 
ferments, . . 9318, 319 
gas pump, . : 7 09 
gelatin, é x 170 


glycogen of blood, 2 “158 


hematin, 252, 254 
hematinometer, = 210 
hematoporphyrin, . 259 
hemin, 5 253 
hemochromogen, 248, 250, 

255, 256, 257 
hemoglobin, by abst 


186, 189, 195, 198, 199, 
206, 208, 225, 229, 232, 
241, 242, 258, 767, 768 
humous substances, . 122 


lactic acid, ; . 109 
lecithin, . ‘ s 2 
liver, . : : oh athe 
metabolism, ‘ . 898 
methemoglobin, 244, 245, 
246 
milk, 126, 129 
muscle, : F 95, 103 | 
nuclei, ; 81 
nucleins, 4 . 65, 66, 81 
oxyhemoglobin, 188, 199, 
200, 205 
pancreatic secretion, . 368 
parahemoglobin, 2)°207 
pepsin, : : . 380 
protagon, 118, 156 
Protéide, . : e428 
proteids, . 41, 46, 68 
pus cells, . 83 
respiration, 695, 725, a 
40 
sebum, : F 674 
secr etion of urine, . 650 
spleen, : 87 


sulpho- -methzmoglobin, 249 
Teichmann’s orystals,. 252 


urea, . . 907 
urinary pigment, . 388 
vegetable globulins, . 51 
vitellin, 3 53, 69 

: sa (5 (2s 430 
keratin, : 73 
leucocytosis, 67, 594 
nuclein, . : . 879 
proteids, . - . 382 


PAGE 
Horbaczewski on uric acid, 67, 586, 587, 594, 
596, 909, 910 


», Xanthine bases, . » Ort 

Horne on coagulation, . . : Pra Ad) 
Hornemann on levulose, 3 : 4 5 
Horsley on myxcedema, é : . 939 
»> 9) Spinal injuries, . . 862 

»» 3, thyroidectomy, . 939, oo 941, 
, 943 
Horton-Smith on peptonised milk, . 136 
Horvath on animal heat, . . 822 
»» 9, hibernation, 795; 796, 797, 823 
v. Hoésslin on iron of food, . : . 886 


Houlston on coagulable lymph, : . 164 


Howell on blood proteids, 162, 163 
Huber on body temperature, : 793 
Teer loynbey : 4 : . 405 

»> 9, liver ferment, : : me o26 

5s 9) proteid absorption, ‘ a eB 

», Salivary nerves, . : ero 2D 
Hubrecht on hemoglobin, . : a | keg 
Hiifner on air chamber ofegg, . . 735 
33 53. biletacidsae ; ; eos 4 

»»  ») blood crystals, . : 233 

a) ag? © a eases 4 766, 769 

»> >, hemoglobin, 185, 192, 193, 195, 


196, 197, 201, 202, 229, 231, 

232, 237, 241, 767, 768, 775 

+> 99, Leucine, - 29, 422 
9° «9 Oxygen of blood, 234, 236, 766 
53 methemoglobin, aeeso: 
247, 248 

»> 9; OXyhemoglobin, . 192, 199, 200, 
203, 205, 206, 223 

»» 9) Yespiration, . 735,178, 119 
+> 5, Skin absorption, . , . 686 
+» 33 Spectrophotometer, 216, 217, 218, 
219, 220, 221, 222 
spectrophotometric constants, 224, 


? 22 be) 


234, 239 

5» 33 Spectrum of blood, : . 209 

»»  », Swimming bladder, E 7705 

»» 9 trypsin, ‘ 337, 340 

99 ~ smbyrosine,s sae 4 : » 423 

ju" 35 AUTOR ae , t : . 584 
Huizinga on glycogen, . : PLS 
Hulse on respiration of feetus, , ah fee 
Hultgren on diet, F : 3 SVAN 
= as heat values, . 874, 875 
Humboldt on animal heat, . , . 840 
~ », respiration, . . 699, 704 

vy. Humnicki on cholesterin, . : Ze 
Hundeshagen on lecithin, . : yim? 


Hunefeld on blood of earthworm, . o 1 186 
Hunter on animal heat, 788, 791, 792, 793, 
803, 810, 817, 823, 826, 849 


5» 3; bile pigments, . - 563 

»> 9», cadaverine, . A : Bee) 

5» 5 fcetal respiration, 3 . eral: 

ss 5) hibernation, : ; 96 

3 S5 lymph, | : P . 287, 303 

» 99 Pigeons’ milk, . ¢ . 676 

3 polycythemia, : - . 3838 
Huppert on bile, . L . 3886, 563 


Js Ps body temper ature, : 2 Gr 


26 , glycogen, . : 14, 15 
” x heron blood, ‘ . 158 
o ,, proteids, ‘ 41, 45 
Huppert-Neubauer on urine, ; pil 


Hiirthle on cholesterin, 5 .  2asaas 


INDEX OF AUTHORS. 


PAGE 
Hirthle on thyroid, . 938 
Husemann on carrotin, PA) 92 
Husson on hematin, "250 


Hutchinson on respiration, 747, 748, 749, 750, 


LOM ol 
ss > salivary secretion, 492 | 
», Spinal injury, 860 
Hutchison on reaction of blood, . 144 
ag ,, thyroid, 89, 938 
IDE on antipeptone, 420 
¥> 3) carnic acid, 103 | 
Inoko on hemoglobin, . 198 
Trisawa on acidity of organs, 108 
»>  3)_ lactic acid in blood, 159 
+ 9 Sarcolactic acid, 106 
Trsal on thyroid feeding, 944 
Isbert on saliva, 328 
JACKSON on residual air, oe SY, 
s », respiration, . ¢42 
Jacobsen on jecorin in blood, eGo 
Jacobson on bile, : 371, 374 
» 53 body temperatur e, 855, 856 
55 » lecithin, a | 
;, residual air, SE Ew) 
Jacobsthal on ripening of cheese, . . 933 
Jacoby on parathyroids, : 940 
»» 3, thyroidectomy, . 9438 
Jacubowitsch on ptyalin, . 9329 
;, saliva, 347, 348 
J aderholm on CO- hematin, ton TG 7 
,, hemochromogen, . 256, 258 
Jaeger on body temperature, 789, 799, 801 
Jaffé on amido-acids in urine, 5 IR 
3» 9, bilicyanin, 386 
»» 9, creatinine, ; ° oe) 
3» » glycuronic acid, 3 : : 5 
»> 5, hematoidin, 384 
Pneeandoxyl, 627 
a5) es5) OFDILhin; . 2 33 
Ri yy spectrum of bile pigments, . 3886 
, urobilin, 388, 620, 622 
Hi akobsen on swimming bladder, 705 
Jakowski on bacterial digestion, 464 
y. Jaksch on alcaptonuria, 607 
9 ,, alkalinity of blood, 144 
5 , blood plasma, . 160 
ey , dextrose in urine, 608 
e , fatty acids of urine, . 615 
93 , gastric juice, 366 
~ ;, indoxy] in urine, 628 
3 ; melanin, 122 
a ;, nuclein, i 65 
2 », peptone in spleen, 88 
;, uric acid, f 592 
Jamin on skin absorption, = 685 
Jankau on bile, : 561, 564 
Jankowski on lymph, a 298 
Jansen on osmotic pressure, 276 
Janssen on body temperature, 822 


Jaquet on hemoglobin, 27, 199, 200, 201, 202, 


203, 768 

Jastrowitz on pentose, ; 3 
Jeffray on foetal respiration, 731 
Jeffreys on residual air, 750 
Jeffries on alkalinity of blood, 144 
Jernstr6m on mucinogen, 62 
Jessen on digestion, 333 
ssi) 35 Lespiration; 742 


IOTS 
PAGE 
Joerg on foetal respiration, 731 
Johannsen on gluten, 53 
Johannson on inanition, 891 


AF aati exchange, 712, 718 
John on ptyalin, . 3829 
Johnson on creatinine, 100, 101, 598, 599 


5 ap respiration of nitrogen, Aeihoo 

ss >» urine, : 608, 609 
Jolin on bile, 376. 
Jolly on osmosis, 274 
Jolyet on respiration, 698, 699, 700, 702, 703 
Jones on blood, 143 
9 1 55 osmotic pressure, 269 
de Jonge on tail-gland, 675 
Joseph « on tail-gland, : 675 
Joubert on gases of alimentary canal, 730 
Joule on heat of combustion, 833 
Jourdanet on mountain sickness, ; 738 

Jousset on body temperature, 801, 802, 81], 
812, 813 

Jiidell on lecithin, ; a 20 
Jungfleisch on coefficient of distribution, 354 


Juretschke on milk fat, : : . 664 
Jiirgensen on body temperature, 789, 799, 800, 
802, 804, 806, 809, 810, 818, 819 


Jurin on tidal air, 748 
9 99 Vital capacity, : H 2 av foo 
KAHN on skin absorption, . 688, 690 
Kamocki on Harderian gland, . 675 
Kaneda on fat formation, 935 
Kanthack on snake venom, . 56 
;, white corpuscles, 152 

Kast on chlorides of urine, 634 
55. 991 Sweat, 672 
Katz on muscle ash, 109 
Katzenstein on muscular metabolism, 912 
», respiratory exchange, 716 

Kauch on glycogen, : : 917 
»> ss liver cholesterin, . 564 
Kauder on blood proteids, 163 
ie 5» globulins, 42 
Kaufmann on bile, . 369 
a ;, blood-gases, 763, 764 

58 ;, CO, of muscle, 912 

“3 ,, dextrose in blood, 915 

i 5, diabetes, 927 

i i glycogen i in blood, 158, 915 

5 », muscle, . : . 841 

Pe Ee respiratory exchange, 841 

ss »» urea formation, 908 

2 3 elmiuseless 103 

Kayser on diet, . 876 
Kehrer on milk, 2 125, 126 
Kekulé on amyloid substance, Ge let 
Kellner on proteid food, 877 
Kemmerich on caseinogen, 140 
73 », creatinine, 101 

- ,, fat formation, 933 

a Sperm 130 

3 tak; 664 

Kenchel on salivary elands, . 512 
Kendall on sweat, 676 
Khigine on gastric secretion, 546 


Kiliani on levulose, : P ‘ 5 


Kinkel on assimilation of ir on, 886 
Kirchner on milk secretion, . 664 
Kirk on aleapton, 607 

»> + uroleucie acid, = 606 
Kirwan on specific heat, : ‘ 838 


1016 


PAGE 

Kisch on proteids, ee dll 
Kisser on proteose, Sree 
Kite on respiration, 748, 749, 751 
Kjeldahl on nitrogen estimation, . 580, 581 
at »» ptyalin, ‘ SPB 
Klapp on cutaneous respiration, 725 
Klebs on intraglobular crystallisation, 191 
Klecki on intestinal secretion, 5 By 
Klein on admaxillary gland, 476, 479 
Klemensiewicz on gastric fistula, 537 
a 3 ie mph absorption, 306 

95 , pepsin, 331 

> pylori ic secretion, 532, 535 

Klemperer on diet, . : . 876 
Klug on cutaneous respiration, 724 
s> 95 muscular metabolism, 916 
5) o>, PEPSIN, 7 . 331 
s» », pyloric secretion, . 535, 536 
vy. Knierem on amido-acids in blood, 899 
5 ;» ammonia in urine, 907 

5 »» aspartic acid, ‘ a 425 

5 », cellulose, 470, 471, 881 
Knop on urea, : ; . 584 
Kobert on hemoglobin, 242, 245, 248, 249 
»» 5, proteid poisons, ‘ eo) 
Kobler on urea, ‘ 585 
Koch on fcetal respiration, 733 
5» 99 gastric juice, 364 
Kochs on hippuric acid, 893 
9 99 Yesidual air, 750 
Kocker on myxcedema, . 939 
Koefoed on butter, 133 
Koeppe on blood, 142 
eS hematocrit, 271 

By es hydrochloric acid of stomach, 276 

9» 9) muscarin, 60, 513 

+» 93 OSmotic pressure, 272 

»> 5, Solutions, 278 
Kohler on body temperature, 822 
Kohlrausch on electrical conductivity, 261 
Kolbe on taurine, 379 
3h. op Eos 5 415 
van d. Kolk on blood gases, : 758 
Kolliker on fish slime, 676 
an ee intraglobular cr ystallisation, 191 

~ se leucine and tyrosine, . 438 
Konig on colostrum, 5 ee) 
ef es diet, 873, 877 
or ass foodstuffs, : tie 
+5) Milk, 129, 130, 131 
oo) DE oteids, ; til 
Kénigsber ger on renal nerves, 644 
Konowaloff on gastric juice, 350 
Kopp on thyroidectomy, 941 
Koppe on muscarine, 60 
Korner on body temperature, 829 
Korolkow on salivary nerves, 525 
Korowin on amylopsin, 336 
53 ptyaling tar. 327 
Koschlakoff on bile salts, 378 
Kossel on adenyl, . 67 
Be cerebrins, 120 

+> «99 GaS-pump, 759 
5) muscle: 5 98, 99 

» ;, notochord, 113 

3, 99 nuclei; see 81 

»» 9 nucleic acid, 66, 67 

y 453, Buclein, 3, 64, 65 
>>») nucleo-histon, = 268 

» 3s) oxyhemoglobin, 199, 200 


INDEX OF AUTHORS. 


PAGE 

Kossel on phrenosine, 120 

92 9, protagon, 118, ELS 

+> 5) protamine, eee OP 

+> 3» pseudo-nuclein, <f fBD 

+> 9) Saponification, . Pa 

pay Eos beSulss e 53 oS 

s thymic acid, 67 

Kossler on gastric juice, . 366 

Kossmann on tail gland, 675 

Koster on whey proteid, . 135 

Kostiurin on amyloid substance, 47 

Kowalewsky on gas tensions, 784 

», respiratory exces . 699 

Kowaski on muscle, : . 108 

Kramm on urochrome, . 619 

Krasser on proteids, a, 28 

Kratschmer on glycogenesis, - 926 

Krauch on proteolytic ferments, peeiol 

Kraus on acidity of blood, . 145 

5» 5, alkalinity of blood, : ay ey 

»» 9 glycolytic ferment ‘of blood, . 161 

+> 9) grape sugar, . 880 

Krause on skin absorption, . 686 

Krauss on muscle glycogen, . - 105 

Krawkow on amyloid substance, mt: 

x », chitin, : ee 

me proteids, , r giles 4 

v. Krehl on fat absorption, 451, 455 

ss », intestinal emulsion, . 448 

53 ,, Suppuration, . 84 

Kretschy on gastric fistula, - . 537 
Kretzschmar on reducing wee of RO 

plasm, . cy) 

Kreusler on aspartic acid, 425 

as , glutaminic acid, 32, 426 

e ,, keratin, , ; 3 

Krieger on body temperature, . 801 

Krimer on blood heat, » (S27 

Kvéger on pancreatic diastase, . 339 

Krolow on Brunner’s glands, 5 ae 

Kronecker on body heat, » 0ar 

55 », skin temperature, 829 

Kriiger on alloxuric substances, 67, 597, 598 

>> . 9) calcium in’ liver, 87 

1 + 9) SClakane ; , 70 

Ey « Mgpne LV SLGane : 426 

s> 9, phospho-carnic acid, 104 

»» . 93 proteids, ‘ 29 

+> 3) Saponification, 19 

ss 33 Spleen, 87 

, sulphur in pr oteids, 26 

Krukenberg on Avthalium, 81 

3 ,;, bilirubin, 389 

- ,, biuret reaction, 49 

a ;> carnine, 102 

- Sse CHMbitiogs 74 

. ,, chlorocruorin, 61 

#3 ,, chondroitin- sulphuric acid, 114 

: ,, conchiolin, atagho 

a3 3, Ehrlich’s test, 384 

; ,, electrical organs, 110 

,, fuscin, 122 

; », glycogen, 15 

30 ,, hepato-pancreas, 336 

- », hyalogens, 63, 64 

,, keratinoses, 73 

; ,, lipochrome ‘of blood, 159 

- ,, proteids, j 5 403 

~ pa Salliveise i eet 

serum lutein, 21 


INDEX OF AUTHORS. 


PAGE 

Krukenberg on tetronerythrin, 21 
ee Ae tryptophan, ? 428 

», urea in muscle, 103 
Krummacher on metabolism, . 9138 
Kriiss on spectro- photometry, 216, 218 
Kuezynski on Brunner’s glands, . 554 
Kudrewetzky on pancreatic secretion, 549 
Kuhn on aqueous humour, - 183 
Ses; milk fat, 664 
Kiihne on albumoses, 410, 411, 412, 413 
»  », amyloid substance, 74 

2 >, antialbumid, 403, 406 
eee antialbuminate, 2 402 

>» >, antialbumose, 407 

+»  », antipeptone, 420 

+2 9) aqueous humour, . 122 

>> 9, bacterial decomposition, 466 

-,  , bile pigments, a ist 

Pea 55 DlOOd; 141, 155 
oe chromophanes, a2 20 

a» a9 COllagen, 430 
ees crystallin, 123 

+> 3, diabetes, 926 

53. 92, Clastin, 72 
ee. emulsions, , . 3 : . 445 

»» 9) enzymes, 312, 320, 340, 341, 517 

>> » glycogen, . 15 

»» 3, hemoglobin, 186, 197, 206, 207, 232 
ee a crystals, 7 232 

ss 9) hemialbumose, 408, 409, 410 

ee 1NGO] 5175 466 

i re intraglobular crystallisation, . 191 
eS isolation of enzymes, . . 314 
eee.) Keratin, ; : - 73 


on 


2) 


lactic acid, : 
leucine and tyrosine, 421, 423, 425, 


437 

lipochromes, . 21 
milk, : 130 
Millon’s reaction, - 47 
muscle plasma, 96 
myosin, 97 
neurokeratin, Pv Gl7/ 
oxyhemoglobin, 244 
pancreas, . : 547 
pancreatic casein, . 137 
3 juice, 448 

‘3 secretion, 551 
paraglobulin, 163 
pepsin, 333 
peptones, aat25 
proteids, ; s 42, 46 
proteid digestion,. 405, 416, 438 
proteoses, : : 5 et 
red corpuscles, 155 
rhodopsin, . 122 
saliva, . 39838275 /503 
Shee 315, 317, 337, 338, 415, 552 
tryptophan, . : - 428 
diabetes, 927 
gastric juice, . . 3849 
glycogen, 15, 397, 918, 919, 920, 926 
isomaltose, Bee lit 
milk gases, 129 
104 


muscle glycogen, 


pentose, . . : 3 
saliva, 346, 485, 784 
starch, ‘ : sa] OLA: 

», digestion, . : Oo 
suprarenals, 90 


108, 109 | 


1017 

PAGE 

Kiilz on urine, 611 
Kumagawa on diet, 877 
- », fat formation, 935 

,, proteid food, Me Sh 

Kunde on blood crystals, 204, 208 
Kunkel on bile, F - 563 
ra IO, 5ehPoy ue Bats! ; - 392 

558 2558 DOCLY, temperature, 829, 830, 831 

3,  »; Sulphur of urine, 632 

,», taurine, 901 

Kunz on pus, : 84 
Kupffer on respiration, . 780 
Kurrer on body temperature, . 814 
Kussmaul on body temperature, 855, 856 
Kiissner on animal heat, ESS 
Kytinanoy on gastric juice, 537 
v. LAAR on keratin, 73 
Laborde on acid of gastric juice, 354 
Lachowitz on parahemoglobin, 207 
Ladenberg on cadaverine, 60 
;, Charcot’s crystals, 94 

Lafont on lacteals, : - . 302 
35 35 respiration, = aglow 
Lagrange on animal heat, . 839 
+3 ;» Tespiration, ion 
Lahousse on peptone blood, 5 alzi7/ 
Lallemand on body temperature, . 820, 821 
Lamansky on intestinal secretion, + 95d5 
Lambert on glycogenesis, 274926 
53 ,, light absorption, 214 
Landenbach on spleen, . 260 
Landgren on inanition, 891 
Landois on alkalinity of blood, 144 
a ;, animal heat, 863 
Landre on body heat, - 855, 856 
Landwehr on animal gum, ‘16, 62, 124, 133, 
613, 665 

5 eeOCIn ae 63 

a », nucleo-proteid of bile, 371 

ne AC synovia, - E 184 
Lane on gastric juice, . 540 
yv. Lang on hemoglobin, 204, 205 
Lang on taurine, . 3/9 
Langaard on milk, . 138 
Lange on blood, 149 
+> 9, Cutaneous respiration, 726 
Langemeyer on muscular metabolism, 915 
Langendorff on diabetes, . 928, 929 
3 5, nervous tissues, 117 

ey ,, Salivary nerves, 483 
Langer on milk secretion, . 666 
Langhans on thyroidectomy, 939, 941 
Langley on antilytic secretion, - 522 
=, , augmented secretion, 497 

= ,, demilune cells, yp ALS 

5, gastric cells, 531, 534 

5A ‘9 5, digestion, 534 

55 ;, liver fat, 935, 936 

_ ah Ss glycogen, . 918, 935 

é 5 pepsin, 332, 404, 542, 543, 544 

“ss , ptyalin, 329, 330 

x , pyloric cells, 532, 536 

, rennin, 335 


-”. saliva, 344, 494, 496, 499, 500, 503, 


504, 509, 510 


salivary glands, . 
488, 


“ 


521, 522, 


475, 485, 486, 
505, 513, 514, 515, 520, 
523, 524, 527 


1018 


PAGE 
Langley on salivary nerves, 480, 483, 484, 506 
a ;» sweat nerves, SE 

A ,, trypsin, 338, 552 
Langlois on heat production, . 846, 853 
,, Suprarenals, 949, 957, 958, 959 
Lankester on chlorocruorin, 61 


se ;, hemoglobin, 186, 187, 209, 242, 


249 
Lannois on intestinal secretion, 556 
35 ,» Skin absorption, 5 eve 
Lantergren on diet, j : Say 
ar ;, heat values, 874, 875 
,, Tespiratory ‘exchange, 718 
Lanz on thyroid feeding : 944 
Lapicque on iron in milk, 86 
Laplace on calorimetry, . 844 
33 », Tespiration, . 693, 694 
Lappe on lactose, . . ooo 
Laptschinsky on lens, 123 
Laroche on respiration, 704 
», swimming bladder, 705 
Laschkewitsch on skin varnishing, 728 
Lassaigne on saliva, . 347 
Lassar on a of blood, 144 
»» >, lymph, 298 
»» 3, Skin absorption, 690 
Lassar-Cohn on cholalic acid, 381 
ab ;, choleie acid, 381 
hs ;, fellic acid, A 7/03 
Latham on proteids, : 39, 109 
Latschenberger on absorption, . 437 
,, bile pigments, . eeoCg 
Latschinoff on cholalic acid, . 380 
3 ;, choleic acid, 373, 381 
;, taurocholic acid, . 455 
Laulanié on thyroidectomy, . . 943 
de Laurés on skin absorption, 685 
Lavdowsky on orbital gland, 478 
;, Salivary cells, . 485 
Laves on milk fat, - . 133 
»> 9, muscle elycogen, ; 105 
Lavoisier on animal heat, 826, 832, 839, 846, 

847 | 

5 ;; calorimetry, : : - 844 | 
33 ,; Cutaneous respiration, 725, 726 
x3 >» OXY PED, \ «« . 7136 
3 , respiration, 693, 694, A Qegub, 


718, 735, 754, 757, 780 


* of hydrogen, y ee 

Lawe es on fat formation, 931, 932, 934 | 

Lazarus- Barlow on absorption, 305, 306 | 

Lea on digestion, . 321, 394, 434 | 
ya) y5.4ermentss. < : 313, 320 
ss 39) hemochromogen, . 256 
>» 5, leucine and tyrosine, 438 
3h epancress: 547 
5g) oy Pbyalin, 328 
ee acennin, 334 
urine, 583 
Leared on sulphocyanate of saliva, 345 
cs ;; sulphur of urine, . 632 
Leathes on diuretics, ; . 648 
3 »» lymph, 294, 308, 310 
a , paramucin, : 5 2 463 
;, Venous absorption, . 3803, 304 
Lebedeff on fat formation, 931, 934, 936 
Leber on filtration, : . 283, 652 
Leclare on fcetal respiration, 731 
Leclere on sweat, 673 
Ledderhose on chitin, 74, 75 


INDEX OF AUTHORS. 


PAGE 

Lefevre on body ear 818 
Legal on acetone, . ti F ~, NOLG 
5 35 Indoljwaie . 469 
Legallois on animal heat, 792, 857, 858 
95 »» asphyxia, A . 745 

ie ,, Tespiratory exchange, . 694 
Lehmann on adipocere, 20, 933 
ce ,, alkalinity of blood, S45 

j , blood, 145 

CA pie As ‘crystals, . § . 204, 244 

ey ,, body temperature, . 823, 863 

i >, caseinogen, - 189, 140 

+ ;; copper in food, : - One 

“3 5» gastric juice, oy 

; », hemoglobin, 204, 206 

- », lnanition, ~ pool 

; », inosite, : ey eLOd 

ss ;, mmvert sugar, . Aue} l3) 

f ;, lactic acid in muscle, 22199 

3 5, milk, : . 128, 663 

; ;, muscle, 5 - oF 00 

se », proteid food, . 878 

= », Tespiration, 711, 712, 715, 717, 
718, 719, 726, 742 

= 7 Salven, ae . 5 343, 347 

5 spectrum, - »208 
Leichtenstern on thyroidectomy, . : . 943 
Lemaire on isomaltose, P by teak 
-3 3, lactose, > eal 
Lemberger on thyroid feeding, . 944 
Lemcke on body meer . 822 
Lentner on milk, ; A ea 
Lenz on calcium in 1 liver, = moe 
55° yp wGiusion: . 263 
Leo on diabetic urine, . 4 6 
»» », fat formation, . . 934 
> 9) gastric juice, . 3866 

Leon. See Mendus de Leon. 

Leonhardt on pituitary body, . 946 
,, thyroidectomy, . 940 

Lépine on body temperature, . 804 
53 «55 Giabetes\iyar 2 928, 929 

»» 39 glycolytic ferment of blood,. 161 

+> 93 intestinal secretion, . 556 

+> 93: Secretion of saliva, . 485 

, sugar in blood, 160, 161 

Lerch on milk fat, « aise 
Lesser on burns, 728 
Letellier on respiratory ‘exchange, 711, 720, 
853 
Leube on chlorides of urine, . F oo 
3: 9) digestion of starch, . 393 
»> 93 gastric juice, . . 3849 
» 9 glycogen, : 14 
5 ates a hea entericus, ; 369, 398 
;, urine, 582, 583, 604 
Leubuscher on gastric secretion, - 040 
Leuchs on saliva, . - noe 
Levenne on diabetes, . 922 
Levick on hyperpyrexia, - 828 
Levy on myohematin, . ~ 92 
s> 3) Skin secretion, » igo 

ss 5, sweat secretion, 678, 679, 681 
Lewaschew on bile secretion, 568, 569 
5, pancreatic secretion, - 49 

Lewin on fat absorption, . 460, 462 
+> 9) intestinal emulsion, . 448 

> 93 pancreatic fistula, . . 366 
Lewith on colloids, eZ 


Lewizky on animal heat, 


862 


INDEX OF AUTHORS. 


PAGE 
846 


Leyden on calorimetry, 
847 


>» 95; heat production, . 


oe 5, respiration, . 698, 707, 718 
Leydig on anal glands, . : < . 670 
»> 55 intestinal respiration, 730 

+> 5, sebaceous glands, . 676 

»» 9, Skin secretion, 673 

,, suprarenals, ; 957 
Lichtenfels on body temperature, . 739, 799, 
802, 820, 821 

Liebe on respiratory exchange, . 102 
Lieben on lutein, . ; 20 
Lieberkiihn on albumin, 26 
x taurocholic acid, 375 
Liebermann on cholesterin, 23 
- ;, dextran, 16 

3 Petats: 20 


ap ,, kidney, ; : : 
lecith-albumins, . 69, 658 

- »; nuclein, ‘ 
oP proteids, . 
Liebermeister on body temperature, 789, 
799, 800, 802, 806, 809, 
810, 818, 819, 822, 825 


2? 29 


~~ ,, calorimetry, 3 . 846 

“fs », Tespiratory exchange,. 695, 
ALFA, 

;, thermometer, . 785 

Liebig « on animal heat, 828, 829, 832, 840, 846 
3» 9, blood gases, . 765 

> >, creatinine, 598 
ee, filtration, 280 

fn 4, 2elatin, 96 

>> >) Mosinic acid, 103 

me >) lexamin, ; pt | 

»» 5, metabolism, . 893, 898, 912 

+» 9», proteids, A 30 

»» 95 respiration, 738, 781 

>> 9, Sarcolactic acid, . 106 

3 9» tyrosine, 423 

», urea estimation, 584 
Lieblein on urine, 577 
Liebreich on cerebrins, 120 
5 ,, hemoglobin, 242 

a ;, lanoline, = nG15 

ne 5s protagon, . 21, 118 

5, Vernix caseosa, 675 

Lietsch on gastric juice, 7 pod. 
Likiernik on leucine, . 29, 422 
Lilienfeld on blood platelets, : 7 56 
iG ;, coagulation, 167, 172, 173 

ue - fibrinogen, z 2 - 164 


nucleo-histon, . : 
proteid of blood, eo 


9 39 


29 32 ” 


a ,, Phosphorus, 84 

Ae », proteids, . 38 

‘, ;, thrombosin, 165 

,, thymus cells, 82 

v. Limbeck on alkalinity of blood, 144 
, diuresis, A 295, 648 

Limbourg on blood, 167 
A », heat coagulation, 42 
Limpricht on inosite, 105 
Pf a leucine, 421 

a7 », protic acid, 103 

», taurine, 103 
Lindberger on trypsin, : . 338 
Lindeman on pentoses, F ; : 3 
Linder on osmotic pressure, . : 2242 
»» 9», Solutions, : 262 


IOIg 

PAGE 

Lindvall on horn, ; 73 
Lining on body temperature, 814 
Linossier on NO-hzemochromogen, 258 
ih ,, Skin absorption, 687 
Lintner on saliva, é 328 
Lipari on respiration, - 742 
Lipp on tyrosine, . : 20 faa 2957423 
Liska on body temperature, - 807 
Lister on coagulation, . 179 
Litten on respiratory exchange, cl 
Litzmann on fcetal respiration, 730, 731 


Liversedge on diastatic zymogen of pan- 


creas, 552 
Livingstone « on body temperatur e, 811 
Loch on Jacobson’s nerve, : 483 

»> 5, Salivary secretion, 484 
Locke on coagulation, 97 
Loeb on muscular metabolism, a ile 

»> 59 Salivary secretion, . . 483, 484 
Loebisch on tendon, 62, 63 
Loew on albumin, 26 

s> 55 formose, : : ‘ : 5 

ay nucleins, 65 

5) 99 proteid constitution, 38 

pnts ;, digestion, 400 

Rath. 3 proteolytic secretions, 330 

sat 55) Urea, ; 33 

»> 3, Xanthoproteic ‘yeaction, 47 
Loewy on alkalinity of blood, 144, 145 

. +> 5) animal heat, 819, 842 
ee oe ultrations 821, 283 


ys 55 Tespiration, 699, 108; 712) (bs 
77, (AGS 7209 7335755: 774 


Lohmeyer on aqueous humour, 122, 183 
Lohrer on ammonia in urine, 907 
Loiseau on raffinose, 12 
Lombard on body temperature, 808 
Long on diffusion, ; 263 
Lénnberg on urine, ; 85 
Loomis on osmotic pressure, . ; . 269 
Lorain on animal heat, 786, 825, 832 
Lorenz on respiratory exchange, secs 
Lortet on body temperature, 806, 807 
Lossen on egg-white, Sa: 

»> 9, Tespiration, a 69850755 
Lossnitzer on pancreatic enzymes, . 340 
Lovibond on colour measurement, a 152 


Léwenhardt on body temperature, ‘ 
Lower on respiration, . ; ‘ 2/456 


Léwit on blood platelets, 156 
»> 5, coagulation, . 180 

»> 9) polycythemia, 143, 152 
Loye on gastric secretion, . 540 
»> 5) respiration, a) AZ 
Lubavin on dyspeptone, 428, 429 
os 5 ,ruuclem: : =) 305 

33) 99) Proteid decomposition, 403 

de Lucea on cellulose, : : 16 
Luchsinger on electrical curr ents, . - 682 
3 », glycogen, 104, 917, 919 

5 3» sweat, 671, 676, 677, 

678, 679, 680 

Luciani on inanition, 888, 891 
Liicke on hydatid eee 63 
mate 9 PUSS 84 
Liideking on osmotic pr essure, 272 
Ludwig on albumoses, ‘ . 440 
Sern osuere | heat, 833, 843, 846, 
850, 852 

4» 9) Dlood gases, 762, 765 


I020 
PAGE 
Ludwig on collagen, 430 
»> 3, dermoid cysts, . 675 
>> >, digestion and absorption, . 442 
»> 5; hemoglobin, 230, 231 
. 4) heatevalue,. . 838 
, > lymph flow, 300, 310, 
et ee »» pressure, 299 
ae oe 5, production, 287, 288, 
289, 290, 293 
aay) 55) muscle: 911, 912 
tn, Osmosis; 275 
35 33 pancreatic secretion, 547 
43, LESpltations.. 759, 782 
95) © a5. Saliivas : 498, 499 
», >, Salivary glands, . 482, 494, 
511, 516, 896 
ans ar nerves, 5 . 482 
+> 9, secretion of urine, 640, 641, 


647, 649, 650, 651, 
652, 654, 656, 658 


ss, uric acid, 592 

Luff on urie acid, : 592 
Lukjanow on bile secretion, : 565 
ie », bone, 111 

;; lmanition, 891 

Lunin on salt-free food, 883 
Lusk on glycogen, 917 
>>», Lactose, é 399 
Lussana on acid of gastric juice, 360 
Luther on sugar in urine, 609 
Lyon on animal heat, 817 
MAASE on liver fat, ; 936 
Macalister on heat production, 842 


Macallum on chromatin, ‘ wadt9 


ib », 1ron absorption, 886 
», in nuclei, 69, 885, 886 
Macfady en on bacterial digestion, 470 
“i 5, reaction of intestinal con- 
tents, 464 
MacGregor on respiratory exchange, 698 
y. Mach on hypoxanthin, ‘ eo 
Mackay on bile salts, . 378 
M‘Kendrick on heat production, . 840 
>, respiration of fishes, . 704 
Mackenzie on blood gases, 766, 769 
A ,, Graves’ disease, 945 
», myxcedema, : - 939 
Maclay on body heat, . - . 790, 866 
MacMunn on bile pigments, . 3888 
sé ,, chlorocruorin, : Gil 
s ,, hematoporphyrin, 260 
> ,, hemochromogen in supra- 
renal . : , -- 90 
‘ », hemoglobin, alts 
,, myohematin, . ; . 99 
nA »» ox-bile, ‘ 385 
i ,, spectrum of bile, 390 
; “ tetronerythrin, ; 21 


, urinary pigments, 623, 625, 626 
Macpherson « on thyroid grafting, 942 
M‘William on precipitation of pr oteids, 41 


Madden on skin absorption, 685 
Magendie on blood heat, 828 


5 », lymph, . ‘ 288, 303 


Be », Skin varnishing, 727 
Mager on caisson disease, - 137 
Magnus on blood gases, 229, 758, 765 
Mairet on pituitary extract, . - . 948 
Majert on Charcot’s crystals, ; - 94 


] 


INDEX OF AUTHORS. 


PAGE 

Makris on milk, 128, 138 
Malassez on blood, 50 
Malfatti on mucin of urine, . 604 
53 «3a MucleInss ee ‘ ‘ Bah 35) 
Malgaigne on blood heat, . _ 828 
Mall on reticulin, ; ‘ : op ota, 
Malpighi on respiration, ‘ 692 
Maly on acid of gastric juice, 352, 358, 359, 
360, 361 

cs Das avaditye a ; w eo7 
> bacterial digestion, . 464 
so) Dilirubiny 384, 389 
»> 5, biliverdin, . 385 
» 55 Cholalie acid, 380 
»> 5, Choletelin, : 388 
€5. lp fee Ges ae = f é s ae 
» 95 gastric juice, . 9353, 355 
est hydrobilirabin, . 387, 622 
5) os, leucines: : - 421, 425 
Re lipochromes, 5 : : se all 
3) 9 Pepsin, 331, 333 
jn 95 Prouew digestion, . 400 


proteids, : : : ee 20 


>> 9, reaction of blood, . lab 
poe ee saliva 345, 346, 347, 348 
- taurocholic aCidt uae - 392 
Manasse on blood cor puscles, oy lob 
or », suprarenal body, 90, 91 
Manché on glycogen, 105, 918 
rs », muscular metabolism, . 915 
Mangili on hibernation, 797, 798 
Mann on peptic digestion, 403 


BS » orypsin, - ‘ ot gED: 
Manning on succus entericus, 341, 369, 399 
Mantegazza on body temperature, 786, 789, 


812, 821 

Maquenne on inosite, . P : ely, 
Marcacci on respiration, 725 
Marcano on bromelin, . : > Paes)! 
Marcet on bacterial digestion, . 464 
S3 ,, blood plasma, . 160 

x ,, body temperature, 807, 817 


emulsification, . . 444, 455 
excretin, j 


5 ,, fat digestion, 443 

r 3) lathy, acids. api 

os ,, respiration, 698, 718, 748 

;, Spirommeter, . ; ahto2 

», xanthin, : . §596 

Marchand on respiration, : 700, 706, 709 

Marchlawski on phy lleporuno in, 382 

Marcuse on casein, an Oe 

3 ;, diabetes, 905, 928, 929 

Pe fy muscular metabolism, «5 O15, 

Ad: ,, sarcolactic acid, . 106 

Marés on urea, 2p a85 

5 1 55) Uric:acid; : i 594, 910 

Marfori on ammonium lactate, 905 

3» 9) iron absorption, 886 

»> 5, oxalates in urine, 614 

Marie on acromegaly, 946 

Marignac on diffusion, . 263 

Marinesco on pituitary body, 945 

Marino-Zucco on neurine in blood, - £60 

5, suprarenals, 90, 948, 958 

Marker on starch digestion, . - . 393 

Marmé on sweat, . 678, 680 
Marquardt on animal alkaloids, ; MBE 

Marshall on alcapton, . ; 607 

5 oy bilews 374 


INDEX OF AUTHORS. 


PAGE 

Marshall on fetal respiration, 733 
Marson on chenotaurocholie acid, 377 
Martigny on blood gases, 758 
Martin on abrin, . 55 
pyaes, althrax- toxin, : ato 

meee 55. bile, -. = : . 369 

= ,,, biuret reaction, ‘ . 49 

»» », coagulation,. 170, 174, 175, 178 
yy filtration, y . - - 282 

y» 9, leucocytes, 180 

») 9) liver proteids, 53 


nucleo-proteid of blood y plasma, 165 


»> 99 papain, ; : 51, 54 

32 99 proteid digestion, 403 

=. >» proteids 275.41 
aaes3) DUS, 83 
ee, saliva, . : 328 

+> 9, Shake yenom, 56, 57, 58, 146 

aan? 53 Spleen, Stele: 

» vegetable albumin, ae Oe 

Martine on body temperature, 786, 791 
Martins on body temperature, SweSLe 
y. Marxow on respiration, - 9 
>, spirometer, . = a2 

Mascagni on lymph absorption, 287, 303 
Maschke on proteid Fig Oe 
Masius on stercobilin, 388, 474 
Masje on body heat, 829, 851 
Masloff on intestinal enzymes, . . 341 
A secretion, 398, 555, 556 

Masoin on thyroidectomy, . : . 943 
Massalongo on pituitary body, . 946 
Masse on fatty acids of liver, - 936 
Massen on extirpation of liver, . 908 
Mathieu on blood gases, 762, 763 
5, Tespiration, . 714, 748 
Matteuci on muscle, . : - 840, 911 
a5 7 respiration, . J8h 
Matthes on proteids, . 4 41 
= ,, Suppuration, 84 


Maurel on body temperature, 801, 809, 811, 
812 


Mauthner on amido- acids, 880 
May on fuscin, 122 
hae inanition, : d . 891 
+2 99 pentoses, . : : : : 3 
» trypsin, . : 338 
Mayer on alkalinity of blood, 144 
3; 5, elimination of iron, 886 

>> 9, hemoglobin, . «hol 
Mayow on animal heat, 832, 839 
a ,, blood gases, - 157 


i  dieb 
693, 704, 730, 731, 
733, vat, 744, 756 


»» oxygen, 
3, respiration, 


29 


Meade-Smith on gastric absorption, 432 
Meara on atmid-albumoses, . : 50 
Meckel on filtration, 280 
Medicus on uric acid, 586 
Mediger on thyroid feeding, 944 
Méhnu on urobilin, 620 
Meissel on fat formation, 932 
4 », Tespiratory exchange, 718 
Meissner on blood plasma, 160 
oe 3 ereatine, «; - - 880 

is ;, muscle, . é - 101, 105 

a ,, peptic digestion, 402, 403, 404 
trypsin, 3 338 

v. Meister on extirpation of liver, | 906 
Melloni on body temperature, 793 


] 


1021 
PAGE 
Melzer on lymph, . 285 
it », pancreatic diastase, i OO 

” », trypsin, 337, 33 
Mendel on lactose, . 399 
3 5, Succus entericus, 398 
Mendus deLeon on milk, 128 
Mengarini on respir ation, : - 105 
Menzies on respiration, 748, 751, 754 
Merejkowski on tetronerythrin, 21 
vy. Mering on carbohydrate absorption, 434, 
435 
ep ,, diabetes,. 920, 921, 922, 928 
34 ;, dextrose in blood, 158 
be ,, fat absorption, . . 459 
- ,, gastric absorption, 432, 541 
¥ ;, glycuronic acid, 5 
se s, hemoglobin, 191 
ae ;, maltose, 394 
53 », muscle glycogen, 919 
35 », ptyalin, 328 
3 ,, Tespiratory exchange, 719 
Fe ,, Starch digestion, 397 
3 », urochloralic acid, 614 
Merkel on respiration, 742 
+» 9, Salivary ducts, 488 
Mesnil on skin absorption, 687 
Mester on gastric juice, 364 
Metroz on sugar in blood, . : Be)! 
Mett or Mette on gastric digestion, . 545 
+» 3, pancreatic secretion, 549, 554 
5» »)- proteolysis, ery 
Meunier on sorbite, 4 
Meyer on ablation of kidneys, w9SH 
»> 39 blood gases, 229, 237, ne 766, 769 
» 9, glycuronic acid, : 5 
s> 5, hemoglobin, . . 238 
Ae Aes internal temperature, 787, 789 
| gs Iron inanilks. : _a8G 
x35 lactosege : 399 
», starch digestion, 395 
Mialhe on ptyalin, - 327 
Michaelsen on thyroidectomy, 943 
Michel on blood proteids, .4 AGS 
> _ 99 proteid' crystals, . . 44, 163 
Miescher on nuclein, . 65, 66, 81, 880 
53 », protamine, songs 
2? »» Pus, - 83 
= spermatozoa, 93 
Mignot on body temperature, 804 
Millar on calorimetry, . 834 
ba 5 Inulingy 14 
+2 9) maltose, 10 
5, 9, reducing power, 7 
Millon on a reaction of proteids, 47 
Milly on cutaneous respiration, 725 
Milroy on muscle proteids, 5 Os 
a ,, thymic acid, ety 
Minkowski on absorption, 443, 459 
45 ;, acetone, . . 616 
>, ammonia in urine, 2 tbs 
cs , bile, 562, 563 
y 3 >» Pigments, - 9389 
¥ ;; CO, of blood, . Yi 
Re :, diabetes, 772, 922, 929 
- », extirpation of pancreas, . 928 

; ,, fat absorption and meta- 

bolism, 461, 462, 931 
- », glycosuria, . 920, 921, 922 
,, hypoxanthin, = yo10 
3 ;, lactic acid in urine, 909 


1022 
PAGE 
Minkowski on muscle glycogen, 105 
= », pancreatic juice, 448 
., reaction of blood, 145 
a ,, salivary glands, 930 
es ,, sarcolactic acid, 106 
, ., starch absorption, . 435 
urine of birds, itl 
Minot on respirs atory exchange, 841, 912 
Miquel on gastric juice, . 3864 
Mironow on milk, . é 663, 664 
Mislawsky on salivary ducts, 488 
a secr etion, 485, 488 
Mitchell on snake venom, . 3 56, 180 
Mitjukoff on paramucin, : yr 
Mitscherlich on blood gases, . Ae hits) 
= saliva, . 343, 347 
Mittelmeier on dextrin, ‘ : a Ks 
Miura on alcohol, 882 
ae | dextrose of blood, 158 
5G , glycosuria, : ; 57 shell 
= 59 inulintet. ; ‘ : <a 
, 55 inversion, 399 
Mohr on gastric juice, . 366 


Pees eratitiens : E : low Wd 
,, marrow fats, 19, 20 
Moleschott on acidity of muscle, . 108 
2 ,, nervous tissues, 115, 116, 117 

,, respiratory exchange, 708, 709 


be) 


Molinari on muscle glycogen, 105 
Molisch on phycocyanin, . : s 52 
¥ », Sugar in urine, 609 
Monari on creatinine, ; 100 
le Monnier on body temperature, ‘ 814 
Monro on lymph, . : 287 
Montgomery on protagon, . ; 1) geil 
Monti on milk, : : . 125 
ss 5: Phosphorus, . : a et 
Moore on chemistry of digestion, ° 312 
BY i iss intestinal emulsion, . 448 
>> 95 reaction of intestinal contents, 453, 
465 

sy) 9) salivary glands, 524, 930 
dela solubility of fatty acids, 455, 456, 
458 

»> 5) Suprarenal body, . 91, 92, 951 
Moraczewski on caseinogen, . 136, 139 
se ;, Duclein, : : - , 44 
Morat on glycogen, 925 
muscular metabolism, . 915 
ss 95, submaxillary gland, 516, 843 


Morax on sulphates of urine, : 5) HAG 


Moreau on intestinal secretion, - . 6b5 
>» 9» Tespiration, . 704, 705 
ss 9) SWimming bladder, as 

Mori on proteid food, 877 


Moriggia on glycogen, { ’ ‘ syortl'5 


: 55 pepsin, 330 
Moritz on diabetes, <i t92i: 
a). ap Slyeosuria, ‘ . 609, 610 
Morkotun on thyroid, . F : Se eis) 
Morner on chondrin, 114 
2 ,, chondroitin- sulphuri ic acid, 115 

,, cornea, 4 5 5° PAL 

Bs Et... 2 muUCcoIdsaare 5 Bh eal 

3 ;. fuscin, ; SS UPAl 

>> >, hippomelanin, 121 

e ,, hydrochloric acid, 365 

a ;, keratin, ; ; : ete: 

a5 sens, & : - ; 5 lS 
ss ;» melanin, 122 


INDEX OF AUTHORS. 


PAGE 
Mérner on membranin, . 3 ‘ «(eee 
ie », mucin of urine, . 604 
3 5, ovomucoid, . ; i +, OS 
5 ;, serum globulin, . £ cf bt 
. >» urea, > 2984 
> Ure; « A : Be tOD 
Morochow etz on chondrin, 114 
35 3, cornea, ‘ 3 = wal 
;, elastin, ; é ~ OR 
Morris on achréodextrin, 396 
: 5, cerebrins, : : ~ 220 
53 ,, dextrin, ; ; 2, 
. “3 diastatic ferments, 12543 

33 », galactose, 
55 3 inulin, 2 : f : « op: 
+ ,, maltose, : 5 . hee, 3) 
starch digestion, 397 


Moscatelli on sarcolactic acid, . 106, 616 
73 », thymus, . : . eas 
,, thyroid, Fs ‘ . 88 

Mosen on blood Hise ‘ ' 


Mossé on body temperature, . 805 
+> 93 glycogenesis, . 923 
53 Sw, MUSCHar metabolism, : 914 

Mosso on body temperature, 801, 802, 807, 

808, 810, 821 
»> 95 Calorimetry, - ‘ ‘ . 845 
56. . 2s. fatigues. 108 
Se clad 5 muscular metabolism, 915 


;, proteid poisons, . : i; ay05 


Mott on body bernperanay ‘ 792 
Moussu on saliva, 5 489 

bs ,, salivary nerves, ; 482 
Mroczkowski on phosphoric acid in blood, 772 
Miihsam on fats of blood, . 30 0) 
Muir on blood sei 156 


Mulder on gelatin, ‘ apeaD 
», keratin, : ; : Leis 


3? 


is 5, neossin, 5 : : wrt Op - 


ee ss proteids, ‘ ‘ : re) 
Miiller on cerebrin, ‘ . : F 


2S 5, chondnn: 121 
= _5,/ digestion, same : ‘ . 438 
elastin, : : an pel 
gy Leute absorption, . . 459 
53) «55 USueslimies 676 
eae hemoglobin, 187 
5 39 Jnanitions 891 
>> a» Lymphatics, \. 287, 303, 304 
a) y5) MUeESA : 85 
5s 33 nervous tissues, 116, 117 
ss 5) Phospho-carniec acid, . 104 
> 9) Ptyalin, 328 
»> 9 Tespiration, 701, 731, 739, 744, 758, 

780 
$0 635 "Skin absorption, . 690 


7 


sputum mucin, . . ~~ oe 
Munk on n aleohol, : 882 


A 5 amido- acids, ‘ 880 
ss 3) ammonia in urine, 585 
5; 3, bile secretion, 2 . 565 
>>, biliary fistula, 460 
; 3, blood plasma, . 160 
Any eaGietsn ws ‘ ‘ ; . 876 
»> >) Giuretics, 648 
pee Pee Toit absorption, 450, 451, 154 aa ee 

1 
>> 99 3, formation, on 90s oon 935 
> 9, gelatin, : F ‘ (tee 
oe La seclycerins 882 


— oo 


PAGE 
Munk on glycogenesis, . 923 
9» 99 inanition, 888, 891 
wees Lymph, ee Loe 
ees, Milk, : 128, 664 
ee. 55 muscular metabolism, 914, 916 
»» 3; potassium of urine, 634 
3s», proteid food, 5 Bil 
ees s; metabolism, 913, 915 
+» 3, Skin absorption, 688, 690 | 
33 93 SOAPS, . 463 | 
5 sulphocyanate of saliva, 345, 346 
»> 9, Sulphur of urine, . 632 
»> >, thyroid gland, 942 
5, ae grafting, - 942 
>, urine, 631, 659 
Miintz on iron in blood, a 150 
Miinzer on urea, 908 
Murray on myxcedema, 940 
= ,, thyroidectomy, 942 
Musculus on achroodextrin, . 395 
— 53 carbohydrate absor ption, 434 
55 », glycuronic acid, 5 
Ac ;, maltose, 394 
a », ptyalin, ‘ . 328 
;, starch digestion, 393, 394, 397 
A urochloralic acid, . 614 
Mylins on cholalic acid, 380, 381 
» 9», Pettenkofer’s test, cy i 
Naparpro on blood gases, 761, 763, 764, 765 
3 3, body temperature, 808 
“A », gas pump, 759 
a », respiration, 841 
,, suprarenal body, 91 
Nigeli on crystalloids, . 52 
Napier on thyroid feeding g, 944 
Nasse on blood gases, 757 
” 53-93 __ heat, 827 
5) colloids; 
» -»» gelatin, 70 
9 «99 glycogen, 15 
Pe.) lacticjacid. 108 
+> 99 liver ferment, 925 
3» >, Millon’s reaction,.. 47 
+> 3, muscle glycogen, 104 
Pe is) ASUSaL, 105 
=), muscular metabolism, 915 
= ey, proteids, 30 
ss Pbyalin, 330 
2 «3; Ptyalose, 394 
,, starch digestion, . 395 
Naunyn on animal heat, 858, 859 


INDEX OF AUTHORS. 


5 », bile, 561, 562, 563, 564, 569 

5 elycogen, 919 
Nawrocki on blood gases, 760, 761, 780 
f ss creatinine, 100 

3 >, gas pump, 759 

ke ,, hemoglobin, 186, 238, 249 

” 5; Salivary nerves, 483 

- 5, sweat nerves, 676 

35 Sy lnssme secretion.» 676, 677, 678, 

679 

Nebelthau on glycogen, 919 
33 ,, sarcolactic acid, 106 
__,, urine of fishes, ; 911 
Nencki on acid of gastric juice, - 359 
3) . >, amido-acids in blood, . 899 
Pe, bilirubin, 384, 389 

+> 3 collidine, ay lyb9 
pees) LETMeHtS, | ge 319 


| 


Nencki on hematin, 

Fey sy hematoporphyrin in, 
intestinal bacteria, 
lactic acid in blood, 
leucine and tyrosine, 
melanin, 
muscle, 
par ahemoglobin, | 
phymatorusin, 

, pialyn, 
portal blood, 
proteids, 


3) 29 


? be) 


rari. 6 ee eediets 
putrefaction, 
reaction of intestinal 
tents, i 
reduced hemoglobin, 
Teichmann’s crystals, 
tryptophan, 
>). 57 Urearin muscle, 
», urorosein, 
Nernst on osmosis, : 3 
Neubaner on ammonia in urine, 
creatinine, 
laiose, 
muscle, 
ne 5, quadriurates, 
a7 Spleens. 
Neuhauss on body temperature, 


9) ” 
2) ” 


39 2) 


Neumann on notochord, 
nuclein, 
skin absorption, 
a ,, thymic acid, 
,, thymin, 
Neumeister ou ae haee site 


+) ? 


> 9 


55 ;; amanitine, 
ammonia in urine, 
atmidalbumoses, 
bacterial digestion, 
bile salts, 

diabetes, 
glycosuria, 
hemochromogen, 
hemipeptone, 
indol, 2 
internal respiration, 
iron in food, 
ovomucoid, 
peptones, 
peptonisation, 
proteid digestion, 
9 ” cy) food, 
proteids, 

ptyalin, 

sebaceous secretion, 
sugar formation, 
tryptic digestion, 


,, tryptophan, . 

;, vegetable ferments, 
Neupauer on residual air, 
Neusser on urinary pigments, 
Newell on coagulation, 

Newport on respiration, 


AP », temperature of insects, 


Newton on thermometer, 
Nicati on gastric juice, 


813, 814, 825 


411, 


266, 273 


100, 


87 
789, 802, 


113 


66, 67 
412, 413, 
439, 441 


415, 416, 


701, 702 
792, 793, 
807 
785 


1024 INDEX OF AUTHORS. 
PAGE PAGE 
Nicol on animal heat, . : . 789,799 | Oidtmann on liver, ‘ f 4 77, 87 
Nicolaides on blood corpuscles in liver, 901 i. » Spleen, -. : : 77, 87 
Nicolas on intestinal juice, . é . 554 | ,, thyroid, . ‘ h sy iS 
Nicolaysen on body temperature, . sms | Oliver on blood corpuscles, : we -150, 15z 
Nicolls on heart work, . ; : 5 ES} | ,, hemoglobinometer, ; by, 52, 
Niderkorn on body temperature, . . 866 5) ‘99 Pituitary extract): : . 946 
Niebel on sugars, : F : ; 3 J J osalivaye é ; : = CAG 
Nilson on colostrum, . ‘ é Srg129 +> 5, Suprarenals, 90, a te 955, 959 
ee. plichenmn, : : k cial gl 4: yo) ose) thymus, 5 . 960 
Nissen on bile salts, . : F oot || , thyroid extract, . . 943 
le Nobel on fat absorption, . , . 459 | Olsavsky on muscular metabolism, . 916 
- ;, hematoporphyrin, . . 625 | Openchowski on gastric nerves, . 538 
+ ;; peptone, . : . 48 | Oppenheimer on muscular metabolism, . 913° 
Nobili on temperature of bees, é ’ 793 | Ord on Graves’ disease, : : a SEs 
Nocard on reaction of blood, : « JADA) Bye. Sthyroidsiee 5 3 «#4939 
Nollonlymph, . 2 . 287, 288, 299 | Oré on bile secretion, . : - . 565 
Nollet on osmosis, : : ; . 273 | Orecchia on thyroidectomy, . : = 1940 
Nollner on kidney nerves, . . 643 | Orlow on absorption, . : : . 3804 
y. Noorden on balance of nutr ition, . 871 | Osborne on diastase, . . 54 
a sn AObTE Ee | . 876 | - 5 fractional coagulation, wo 48 
’ spectrophotometry, - 224 | ee », vegetable proteids, 3 . 54 
North on muscular metabolism, . 912, 913 | a 57 witelling am P eS 
Nesinagel on bile pigments, : . 389 | Osiander on feetal respiration, ‘ werol ; 
;, suprarenals, . ; . 948 | Osler on blood platelets, : i - 56 
Notkin on thyreoproteid, . : . 89 | Ostroumow on sweat secretion, . - 606 
if by thyroid, 7 x . : - 938 | Ostwald on mechanical affinity, . 275, 276 
Novi on diet, : : : : wot .| », solutions, . : . ‘854, 650 
ES go) Deomaimes; ) <: : - oe oe) OF Sullivan on maltose, . u 394 
BO At salivasie : : : - 510 | ;, reducing power of dextrose, 7 
pee on respiration, . : . 695, 700.| Ott on animal heat, . : 858, 863 
Noyes on body temperature, : stele |) Bye 5, skin secretion, : 4 677, 678, 680 
Nuck on lymphatics, . : . -.. 802) | 5.5, Suppuration; 4 84 
Nuel on blood gases, . 2 . 776,778 | Otto on carbohydrate absorption, . . 435 
Ae tension of gases, . : -, 784 |. 535 -;,%cerebrins; g 5 : sas 120 
Nussbaum on alveolar air, . : a thie ss 5, dextrose in blood, . : 258 
be ,, secretion of urine, . 655, 656 »> ;, OxXyhemoglobin, 197, 199, 200, 205 
a , tension of blood gases, . 776, »> », tryptic digestion, . : . 416 
777 | Overton on plasmolysis, c ‘ a, 
Nuttall on bacterial digestion, . - 465 Owen on skin glands, . 670 
5> 3; intestinal bacteria, . . 26 | Owsjannikow on intraglobular erystalli- 
Nylander on dextrose, . Z - =_) O10. sation, d ~ SLOn 
Nylén on ptyalin, : if . 329, 330 ae ,», salivary secretion, . 492 
OBERMAYER on indigo, ; : . 627 | Paat on gelatin, . : ’ . -5 «f0 
», urine, . 3 : aero yee >» peptones, . f ee fil 
Obermeyer on proteids, , : ye 48 +: 39 proteids, : , . eer 
,, skin absorption, . - 687 | Pachon on coagulation, : J 174, AGS 
Obermiiller on cholesterin, . E . 283 | Page on respiration, . . 707, 712, 848 
e saponification, : 19 | Pages on coagulation, 135, 147, 169, 170, 171 
Obernier on body temperature, 790, 807, 816, | Pagliese on nitrogen excretion, . 876 
824 | Paijkull on bile, . - : : 84, 372 . 
Obolensky on mucin, . : : 62, 63 | Painter on ptyalin, : Y ; - 330 
O’Brien on proteids of flour, . : . 54 | Pallas on hibernation, . : : - 197 
Ocaiia on suprarenal extract, : . 951 | Panasci on salivary nerves, . ; . 525 
Oddi on chondroitin- sulphuri icacid, . 115 | Paneth on succus entericus, . : . 554 
»» 9) muscular metabolism, . - 913 | Panormoff on muscle sugar, . : - 105 
+> 95 respiration, . : . 708,711 | Pantyuski on renal secretion, : . 654 
Oehl on saliva, . . 842, 343, 345, 492 | Panum on fetal blood, r ‘ sf 82 
Oehler on electrical currents, = 5) Ue bas gastric fistula, 3 j PON, 
Oertmann on body temperature, . 786, 825 | ) s.wsepsiles - : ~~ (59 
A ,, respiration, 699, 703, 756, 781, | Paoletti on muscular metabolism, - 4 915 
895 Pappel on milk, . : : : »_ dat 
Offer on uric acid, F : : e592, | A egg OW, fikose, ‘ é . 132 
Ogata on collagen, : - : . 430 | Pappenheim on tryptic digestion, . 414 
Pe; ; digestion, : : . 442 | Parcus on cerebrin, : , - 120 
Ogle on body temperature, 788, 789, 799, 800, | Parisat on skin absorption, . , - 686, = 
803, 807, 809, 820, 824 | Parke on lecithin, : : J 5 
Oglesby on body temperature, . - 821 | 955. 27) taurocholic acid,.ar : 375 
Ohimiiller on diet, : . : . 877 | Parkes on body temperature, : 820, 825 


Oidtmann on kidney, ‘ d : . eee ss 3) muscular metabolism, . . 912 


INDEX OF AUTHORS. 


PAGE 
Parkes on urine, . 572 
Parrot on osmosis, 273 
Parry on animal heat, 817 
Partsch on milk secretion, 666 
Pascheles on electro-osmose, 688 
Paschkis on bile salts, . 391 
Af >» >», Secretion, ew 

3 ,, cholagogues, BOG, DOO 
Paschutin on cane-sugar, . : . 398 
ris » curari, : 298 

¢ 5, enzymes, 329, 339, 340, 342, 

556 

- », lymph « 289 

;, succus entericus, 398, 399 

Pasteur on racemic acid, 5 ys 
Paton on bile, 371, 561 
ets | 55 "pigments, 563, 569 
Pause) | 55) Secretion, 559, 560, 567 

Pa ., tasting, . 888, 891 

a +5. tab absorption, . 460 
so >» production, 924, 935 

9 9, fatty acids of liver, 935, 936 
sliver fat, f 935, 936 
Pease) glycogen; 926, 935 
Passe 4s). Lassie, - 564 

>> 5, muscular energy, : . 916 
», proteid crystals, . : crm eed: 
Patrizi on body temperature, : . 803 
Paulesco on proteid quotient, 162 
Pautz on aqueous humour, 122 
Bayes) lacLose; : 399 

ss 9, Succus entericus, 398 
Pavy on amylolytic ferment of liver, 926 
s> >, dextrose in blood, 158, 159, 161 
Pees tat formation, . 935 
os 2lycoren; 16, 917, 924, 925, 926 
» » glycolytic ferment of blood, 161 
eas, lactose; |; shaw2 
>» »5 phloridzin diabetes, 921 
CRM J; proteids, ‘30, 64 
5, sugar in urine, 608, 609 
Pawlow on coagulation, _ ilffs 


‘. >, gastric fistula, . F 4 bey 


“5 ne a secretion, 349, 539, 540 
a 5, pancreatic secretion, 547, 548, 549 
55 ,, proteids of diet, j Bier 
‘. ,, salivary glands, 487, 488, 512 


;, urea formation, . - - 908 
Payen on starch digestion, 
Pecquet on lacteals, - ; : 
Peiper on blood, . : : . 143, 144 
Pekelharing on albumoses, : : 
cell globulin, c 82 


29 29 


Ls ;, coagulation, 167, 170, allay 
177, 179 

te ;, fibrin ferment, . «| 82 

‘a ,, nucleo-proteid of blood, 165, 

166, 171 

re - muscle, 98 

‘ ’ proteose of blood, eGo 

Pellacani on intravascular coagulation, 173 
33 suprarenals, 90, 950 


Pelouse on gastric juice, : : . 352 
Pembrey on animal heat, 785, 789, 790, 799, 
804, 821, 830, 840, 848, 

850, 859, 861, 865 


if ;, cachexia thyreopriva, 941 
,, heat regulation, . 735, 866 
An ,, hibernation, 795, 796, 797, 866 
E. ;, oxidation in tissues, 895 

VOL. I1.—65 


1025 


PAGE 

692, 696, 697, 698, 
703, 706, 707, 708, 
717, 723, 781 


Pembrey on respiration, 


a ,, second wind, PY) 
> », warm- blooded animals, 713, 714, 
866 


Pepys on respiration, 695, 698, 735, 736, 739, 

748, 750, 754 
Perewoznikoff on fat absorption, . 451 
Pernet on spleen, ; é . 959 
Pernon on iron in milk, ‘ ; EAE 


Perreri on body temperature, 821 
Perrin on body temperature, 820 
Peschel on proteid food, 876 
Peters on casein, 137 


bac hepatin, é j 69 


Petersen on respiration of fishes, 704 
Petit on enzymes, 317 
+> >, heat value, 834 


Petri on toxopeptone, . mer 


Petriquin on cerumen, . 675 
Petrowsky on nervous tissues, 115, 116, 118 
Pettenkofer on bile acids, ; Sha 
fe ,, fat absorption, 454 

a 3, >» formation, 933 

5 ,, manition, . 887, 889 

5 », Tespiration, 695, 696, 699, 700, 

707, 708, 716, 718, 

721, 781, 808 

Pfeffer on gases of saliva, ; . 346 
tye pe OSMOSIS, 276, 284 

>> 3) OSmotic pressure, 265, 266, 267, 
278, 650 

+> 9; Semipermeable membranes, 264 
Pfeiffer on melanin, 122) 
2 janis 128 

3 ;, pepsin, 333 

» ,, phymatorusin, Pal 
Pfliiger on animal heat, 833, 859 
+ ,, balance of nutrition, . portevs il 

a) ,, blood gases, 154, 761, 762, 767, 
770, 771, ti 778, 780 

- 5, curari, . 842 

55 5» gases of bile, 784 

ie 53 93 saliva, 346, 347, 504 

; », gas pump, : Se iy 

. », glycogen, 920 
Be 5, glycogenesis, 923 

5 ;, metabolism, 914, 924, 935 

an milks ; F . 130 

7 ,, oxidation, . : ‘ Ay (ek 

3 > proteid diet, 892 


metabolism, 898, 903, 913, 


3? se) 39 


915 
A », proteids, 38, 897, 899 
ae ,, reducing substances of blood, 152 


- », respiration, . 694, 695, 699, 710, 
WAN, 713, Ml alo2s 740, 
749, 750, 756, 756, 757, 
765, 174, 780, 848, 895 


5 », synthesis in metabolism, 25, 893 

3 ;, urea estimation, . . 584 
Philip on animal heat, . 857, 858 
Philippeaux on suprarenals, . . 948 
Philips on maltose, 397 
Phillips on diuresis, 649 
os 53 respiration of oxygen, 736 
Phisalix on pigeons’ milk, : 676 
,, skin secretions, . 673 

Picard on blood plasma, 160 


1026 
PAGE 
Piccard on protamine, . : : 6893 
Piccolo on lutein, : ‘ ‘ a, 220 
Pick on glycosuria, c : e OR 
Pickardt on dextrose in blood, : = Wl'b8 
Pickeri ing on biuret reaction, : : 48 
Rs ,, coagulation, . a be eeliy 
2 i colloids, ; , 37, 146 
of », copper reaction of pr oteids, 48 
ia 5, proteids, . srw 
= 5, synthesis of proteids, Bi rast 
, xantho-proteic reaction, . 47 
Pictet on animal heat, . : : - 19823 
aa) use Rellechsl on cold, : : B basil) 
Picton on osmotic pressure, . é - 272 
SJ esesolubions,, | ;. 5 : - 262 


Pierini on skin absorption, 686, 687, 689 
Pilatre de Rozier on respiration of hydro- 


|  gen,. : ; : . 739 
Piloty on elycuronic acid, ‘ : : 5 
| Pinkerton on body heat, . : Hy 1812 
_ Piria on tyrosine, : ‘ . 424 
| Pirri on bile, 4 . poor 
Pisenti on pituitary body, : ; . 946 
Pitts on body temperature, . : SI 
Pizzion milk, . 130, 1381 
Planer on gases of alimentary canal, te (29 
a ess peritoneal fluid, . : Per in fey! 
Plato on animal heat, . : : - 8382 
Plattner on bile salts, . : - 3812, 374 
_ Plész on albumose in blood, . : . 489 
ss >» liver proteids, 85, 86 
So suuuclein., .. F J 65, 81 
1 WSs) 3. proteid food, . ; ‘ Bo says! 
Plugge on ptyalin, : . : . 330 
_ Pochoy on animal heat, : : . 858 
Podolinski on NO-hemoglobin, . . 239 
re ,, pancreatic extract, . 5) ay? 
| », trypsin, . : . . 338 
vy. Poehl on proteid digestion, . . 400 
| », Spermine, . : f Ss 
Poggiale on fcetal blood, , me ("4 
ES », milk, : : 22 130 
Pohl on carbohy drates, ; : nee 
eessmnuclein, < : ‘ sO 
+> 5, polysacchar ides, ‘ ‘ als 
ss», proteid absor ption, : : . 441 
| Politzer on proteid food, é : - ofS 
_Ponfick on burns, ‘ : - 128 
Ns Pas extirpation of liver, ‘ - 906 
+> 3) proteid food, : 3 ) S48 
Popielski on pancreatic secretion,. 549, 550, 
551 
_ Popoff on caseinogen, . 5 : ley 
5» +, nucleo-proteids, . ; Ou 
>> 9) proteids, ‘ : : . 333 
| Porret on electro-osmose, . 2 . 688 
Porter on excrements, . 5 ; Sie, 
ae) weg UTING, -o, : : E ear (ice 
_ Possell on spongin, 76 

| Pott on respiration, 702, 703, 706, 708, 720, 
734 
_ Potthast on amido-acids, : . 880 
_ Pouchet on leucomaines, . é = @ik6H 
| Poulet on skin absorption, .*  . . 685 
| Praussnitz on diabetes, ‘ ‘ 07921 
na <3 glycogen, 5 - 105 
Re 5, Inanition, ; - 888, 891 
», vegetable proteids, . cileabil 
| Preal on succus entericus, 342, 369, 556, 557 
_ Prévost on bile, . é : F E563 


INDEX OF AUTHORS. 


PAGE 
Prévost on bile salts, . ; : «892 
»» », body temperature, . . 0790 


so) SES Canines 
Preyer on blood crystals, 


. . 514, 520 
194, 205, 208, 209 


3 ssp nga @asesNre 761, 762. 772 
+» 5, body temperature, ; . 804 
fF osmalobinty : ~ 244 


189, 195, 198, 248, 
767, 768 
»» 5, lntraglobular crystallisation,. 191 


ss 55 hemoglobin, 


»> 55 Lespiration, 732, 734, 735, 747 
Pribram on blood salts, ; 157 
5; », gastric juice, . : 4 pool 
Pr tear on animal heat, . : . 839 
e , blood gases, ; ago 
A aS cutaneous secretion, . & 725 
¥ ,, lymph hearts, . 301 

a 5, Tespiration, 


693, 694, 735, 739, 
756 


Prochaska on lymph, . : . . 287 


Prompt on salivary secretion, : . 490 
Proust on leucine, A : : - 421 
so ve 55) ULOerythriny : ; - 6238 
Prout on acid of gastric juice, . 351, 352 
5» 9) Tespiration, 698, 721, 754, 803 
Provencal on respiration, 699, 704 
Provoost on body temperature, ©. Be sls 
Purdie on lactic acid, . ‘ . LOT, 
Purdy on urinary phosphates, : . 633 
Purkinje on tryptic digestion, . 414- 
Putzeys on pepsin, : : . 3832 
Pye-Smith on intestinal secretion, 555, 556 
35 ,, salivary secretion, . ») 528 
QUAIN on adipocere,  . ; tt) 
Quatrefages on chlorocruorin, ; + 961 
Quervain on thyroidectomy, - <4 94 
Quetelet on respiration, : : oy CET 


Quevenne on milk, ; sigl2g lar 
Quincke on body temperature, 822, 823, 858, 


859, 867 

rf. ,, elimination ofiron, . . 886 
s », emulsion, . : . 445, 446 
oA ., gastric juice, . : - "ong 
c ,, hepatin, . d : A ee: 
Be ,, ironin liver, . F sco 
Dy ,, milk globules, 125, 446 
e ,, Skin absorption, 3 . 686 
an ;, Ssuccus entericus, : . 869 
5, urine, : : : 08530 

( Quinquaud on blood, 141, 160 
xe 5 alycogen, : : - 918 
a , hemoglobin, . 231 


respiration, 700, 703, 707, 711 


9? 7 


RACHFORD on emulsions, 444, 445, 448 
ee ,, fat absorption, 452, 461 
ss », pancreatic fistula, . . 866 


js plalymy & : 5 . 340 
Radziejew ski on aspartic acid, . . 425 
i ab absorption, 451, 931 

;, tyrosine, 


Rahn on salivar y nerves, 
Rajewsky on alcohol, 
Ralfe on gastric juice, : 
Ramsden on fractional coagulation, 
Ranke on diet, : 
eye fatigue, 
ie os: dnantions 


INDEX OF AUTHORS. 


PAGE 

Ranke on respiration, . : . a9n/08 
23 », tetanus, - : - 2 BELO 
Ransom on glycogen, . : : . 919 
Ranvier on elycogen, , : . 84 
;, ,, retrolingual gland, : . 476 
Raoult on diffusion, ; ; : . 264 
+> :, OSmotic pressure, . ‘ - 269 
Rappel on isocholesterin, —. : . 24 
Raps on gas pump, : 5 GY) 
Rattray on body temperature, : 5, le 
Rauber on milk secretion, . . 665, 666 
Raudnitz on body temperature, . 804, 866 
se =) 10a Ze : : : 2) 126 
Rauschenbach on pus cells, . : 5 8B 
Ray on respiration, . : 2 5 el 
Raymond on sweat nerves, . : 5 ORE 
Réaumur on animal heat, . - 793, 823 
»» gastric digestion, . 401, 536 
Rechenber gon heat value, . , . 834 
Recklinghausen on lymphatics, . - 299 
Redard on body temperature, ; S25 
Redtenbacher on taurine, . ; 373 
Reeve on hibernation, . : 796, 798 
v. Regéczy on filtration, 280, 281, 282, 283 
de Regibus on nervous tissues, . 5) als 
Regnard on body temperature, - 817, 841 
rin ,», gastric secretion, - . 540 

se ,, hemoglobin, F 187 

B ,, Tespiration, 699, 700, 702, 703, 
781, 782, 840 

Regnault on hibernation, . : 5 SS. 
at ,, respiration, 694, 700, 703, 706, 


707, 709, 711, 720, 723, 726, 
736, 739, 762, 765, 853 


Reichert on body temperature, 821, 844 
*s ,, lodine in urine, . . 688 

;, snake venom, 56, 180 
Reid on cutaneous respiration, . . 725 
;, >, diffusion, F : : 4 261 
+; >, electrical currents, . : . 684 
pease ulbration, : ‘ . 280 
»> >, intestinal absorption, . 284 
:» 3, Skin absorption, 690, 691, 725 
Pukey. 5; secretions; i - 669 
>» - >, Slime of eel, 674, 676, 681 
> >, Sugar of blood, : : wel Gil 

, temperature of liver, 843, 896 

Reincke on body temperature, 3 2 821 
Reinhard on cutaneous respiration, - 126 
Reinitzer on cholesterin, 5 ; - 2 
Reinke on 4thalium, . : 2 aa Weill 
», », Cholesterin, . ¢ : ee! 
put, flycogen, js : , ely 
Reiset on hibernation, . : 5 7h 


>» 9, respiration, 694, 700, 702, 703, 
706, 707, 708, 709, TY, 720, 
723, 726, 736, 739, 765, 853 


Reiss on mannose, : 7 
Reober on electrical cur rents, : = 682 
Reoch on gastric juice, . < - . 365 
Retzius on salivary nerves, . - 3 RS 
Reverdin on thyroidectomy, : . 939 
Rey on lime excretion, . : : oe 
Reynaud on body temperature, . - 812 
Reynolds on second wind, . 2 . 747 
Ribbert on secretion of urine, 2 656, 657 
Richardson on body temperature, >, 82ii 
3 ,, intraglobular crystallisa- 
tion, . z ae HORI 
, », respiration, . : a (es 


1027 


PAGE 

Richerand on tidal air, : 4 shee 
Richet on body temperature, 789, 790, 791, 
792, 799, 801, 821, 824, 

842, 845, 856, 863 


» », gases of alimentary canal, . 730 
33 >) gastric fistula, : = | BBY 
| ee juice, 349, 353, 394, 355, 

539, 545 
Sy. ap Mento, |. 3 5 ei 
5; 3, Tespiration, 699, 708, 707, 708, 


709, 713, 714, 716, rate 718, 
720, 748, 752, 756, 916, 933 


o) Ol,g unea- forming ferment, : meood 
Richmond on milk, . : : 5) 83! 
Pe tewfikose, : F 7 lisZ 

Richter on thyroid feeding, ; ; . 944 
Rickards on body temperature, 820, 821 
Riegel on animal heat, . 856, 859 
Riess on sarcolactic acid in urine, . . 616 
Rind#leisch on skin absorption, . . 688 


Ringer on animal heat, 789, 799, 805, 809, 


819, 820, 821, 824 


se >> casein, ; 137 

ae », caseinogen, . 136 

As », coagulation, 42, 43, 185, 169, 170 

,, oxalate of lime, . 171 

Risler on hemoglobin, : - sre2olk 
Ritter on diabetes, : ‘ ~ 192055921 
>» 5, proteid food, . ? : . 876 

»> 5, Skin absorption, . j a ef 

»> 5, urea, . : : P ‘ 33 
uric acig, j é ng? 
Ritthausen on aspartic acid, . 425 
m” HE carbohydrates of milk, 0 32 

32 ,, glutaminic acid, 32, 426 

a ,, legumin, : ‘ a! 

is ;, mucedin, 53, 54 

;» proteid crystals, ; y, OZ 

Riva on ur ochrome, . ‘ ; . 620 
+e 3 UE oerythrin, - . . 623 
Roberts on digestive solutions, ; eae 
i, . metacasein, : - Se, 

_ >, pancreatic casein, 137 


9? 99 7) 


enzymes, 336, DEE 338, 
339 


. », ptyalin, . : : - 327 


%, », quadriurates, ‘ . 588, 589 
33 », urates, = - a2: 588, 590 
3, », uric acid, . 3 . a0 Dil 
urine, ‘ é . 637 
Robertson on body temperature, . 790, 8035 
Pe », gastric fistula, . P MWSS7 
;, respiration, . : . 153 
Robillard on Sweat, ; . 679, 680 
Robin on h cematoidin, 2 : - . 384 
Robson on bile, 571, 560, 561, 562 
Roch on proteids, F £ J ay 74 
Rockwood on antipeptone, . : -,, 420 
x 5 dabuy acids, 5 455, 456 
a ,, intestinal emulsion, . 448 

35 ;, reaction of intestinal con- 
tents, ©. 453, 465 
Rodewald on cholesterin, . j ny! (24 
35 », glycogen, ; : SOLD 
Roger on body temperature, . - 804, 805 
Roget on body temperature, . : = O07 
Rogowicz on lymph production, . 5 exalt) 
Pe », pituitary body, . ; . 946 
EB ,, thyroidectomy, 939 
Rohmann on absorption, 399, 431, 462 


1028 
PAGE 
Réhmann on acidity of organs, . . 108 
4, ,», biliary fistula, . ‘ . 460 
5 ;, diabetes, 928, 929 


a 5, diastatic ferment of blood, 160 
, fats in blood, ae es 
5 », glycogen, . E ‘ . 919 


., », intestinal secretion, 368, 555, 
556 

* 5, isomaltose, ; : 5, elZ 
re > liver, F : PO 
, », Starch absorption, : . 435 
,, sugar in blood, ; 2° L6L 

Rohri ig on bile, : ee 560.565 
ee pies fats of blood, 3 ; HOLS9 
Fen cpp een secretion, - : (ay) 
>> 9, Lespiration,. 699, 711, 726, 727 
»> 9, Skin absorption, 686, 687 


Rolleston on heat formation in nerve, . 808 


nA ,, Skin temperature, . . 830 

», Suprarenals, . 5 288 

Rollett on blood, 142, 143, 145, 212, 213, 233 
sana eee of earthw orm, : e eSG 

»> 9, hemoglobin, 194, 204, 230, 231, 
232 

is 9) red corpuscles; ** : gists) 

,, tendon, ; ; si 962 

Ronchi on cutaneous respiration, 726, 727 
Rondeau on body temperature, 789, 801 
Roos on sugar in urine, . : - 608 
», », thyroid feeding, : ; . 944 

a tye thyroiodin, 3 < F or 489 
Roosen on uric acid, . 586, 587 
Roscoe on extinction coefficient, : . 214 
Rose on bile, : : ‘ : a diel 
Rose on paracasein, . 6 . 134 
Rosenbach on bile pigments, : - 386 
Rosenberg on bile, 560, 563, 566, 568 
,, fat absorption, . . 459 
Rosenblatt on thyroidectomy, ‘ 2) OH 
Rosenheim on proteid food, . : 2 - 816 
Rosenstein on fat, : 462, 931 
, lymy a E : eS? 


Rosenthal on body heat, 812, 824, 826, 839, 
845, 846, 854, 859, 863 


Ap ,», electrical currents, , . 682 
Rosin on indoxyl, : ; : . 628 
» 95 Urorosein, - i t ; 7628 
Rosow on fuscin, . ‘ : ‘ od 
Ross on animal heat, : 823, 851 
Rossbach on sweat secretion, 3 680 
Rothon-Duvigneaud on thy roidectomy, 939 
Rouelle on urea, . : ‘ 5 | axetil 
Roux on reaction of blood, ; 4 pelt 
>> », tetanus toxin, : { Sp lh tes 
Rouxeau on thyroidectomy, : : - 939 
Royida on hyaline substance, : SIGs 
Roy on cerebral circulation, . : . 808 
3» 9, Oncograph, : ki b . 643 
3» 9) Oncometer, c . 643 
»> 9 Specific gravity of blood, é reali. 
>uspleen))'*: ; . 960 

de Rozier. (See Pilatre de Ro: wer. ) 
Rubbrecht on blood proteids, : . 162 
Riibner on calorimetry, 4 . 845 


ape 35 pares absorption, . 436 
a ,, fat formation, 932, 934 
Be) ay eat production, 832, 833, 834, 
835, 836, 837, 841, 
846, 851, 853, 854 

834, 838, 874 


39 2999 value, - 


INDEX OF AUTHORS. 


PAGE 
Riibner on inanition, . i a . 888 
45° egy isodynamy, - > 865 


S53, LeSpiraniony 4123 718, 719, 720, 721 


Riidbeck on tea eae 286, 299, 310 
Riidel on rickets, . 4 : . 886 
a 45) WURIC acid, : f : . 588 

AeA gelunhaey | i é - 580 
Rudneff on amyloid substance, ; . 74 
Rudolphi on animal heat, . : - 793 
ae », proteids, . Ae 3) 
Riidorff on freezing point of solutions, - 269 
Ruge on gases of rectum, : : - 729 


Rumpf on body temperature, 808, 821, 842 


ee a respiratory exchange, 713, 717 
Runeberg on casein, . : . 878 
- .; filtration, : 280, 281, 282 
Ruppel on milk fats, . : 133 
9) 53 Protagony i: : 5 . SG 
+> * 9) Vernix.caseosa; 1% ; Sagons 
Russ on glycogen, : : steel 
Russell on blood platelets, : é elas 
Rustiksky on marrow, . ; ‘ Ho tilat 
Rutgers on proteids, . : 3 eZ 
Rutherford on bile secretion, 567, 568, 569 
», gastric secretion, . oad 


de Ruyter on body temperature, . - 855 


Sr. ANGES on respiration, . , . 734 

St. Bondzynski on cholesterin, . vy (24 

St. Hilaire on fcetal respiration, é 731 

St. Martin on respiration, 717, 721, 741, oh 
St. Pierre on blood gases, : . 762 

Sabanejeff on glycogen, - : a tS: 

5 ,, osmotic pressure, . . 272 

a ,», proteids, . : ae 7/ 

5 proteoses, : : + #246 

Sacchi on pituitary body, 945, 946 

Sachs on blood, . ‘ : . 780 

jit 50), 155 "eases 761 


Ss, Doky, temperature, . 792, 863, 864 
55 3, carbohydrates, : 2 a PAL 
», temperature of plants, . . 849 


Sachsse on vegetable proteids, c 52, 53 
Sainsbury on coagulation, 42, 169, 170 
Saissy on blood heat, : Beal 


»» 3, hibernation, . 794, 795, 797, 798 
Salkowski on amido-acids in blood, . 899 
= >, ammonia in urine, . sem85 

AF », aspartic acid, . - - (425 

ie », bacterial digestion, . 466, 467 

3 57) DLood Saame- $ : umellb2 


‘5 », caseinogen, : u 186 FSe 
uf ,, chlorides of urine, . . 634 
6 », cholesterin, . : he 
Pr », creatinine, ; ‘ 8s 
ie ,, dyspeptone, . ; -, 429 
2 >> datty acids, sous F o 451 
Be 55) 5p egy ei ofeunines seiG5, 
oa yp celatanser ; F oO 
a », hematoidin, . ‘ . 384 
- »» Lind olaatme A : . 468 
53 ,, liver ferment, . : in 925 
$5 ,, Millon’s reaction, . on RSsi 
+ », muscle, ; : Jee OG 
55 ;, ovomucoid, . : eas 
55 », pentoses, . : 3, 612 
- », pigments of urine, . ») 625 
oy », potassium in urine, . . 634 
9 ,, proteids, . ‘ 26, 46 


= =" 


——~ 


INDEX OF AUTHORS. 


PAGE 

Salkowski on pseudo-nuclein, . 136 
nf », Skatol-carbonic acid, 467, 469 

os ;, sulphates of urine, . .» 632 
fs », Synovia, ° 184 
re »; urea, - : 2907 

55 »» uric ‘acid, . 592, 594, 595 

* », Xanthin bases, . 597 

te ;, Xanthoproteic reaction, 47 
Salomon on glycogen, . ; 14, iy Gale 
- a of blood, 2 lb8 
ee ., hippuric acid, 893 
Bass lactic acid/in "blood, 159 
” >, pus, . . 84 

ee ss ures, . - : 906 
ys08y,) Lormation, « 902 

Salvioli on albumoses, . . 440 
»> >, coagulation, 147 

eee 3) Lymph, : 182 

s> 5; peptone blood, 177 

,, proteid quotient, 162 
Samojloti on digestive solutions, 325 
Sanctorius on skin, : 27 
39 ;, thermometer, . 85 
Sanders-Ezn on respiratory exchange, . 699, 
(Alle 7Als 

Sandmeyer on caseinogen, 137 
re ,, diabetes, : 928 

A ;, intestinal emulsions, 448 

»» pancreas, 443, 459 

Sandras on starch digestion, . 393 
Sanguirico on thyroidectomy, 939, 940 
Santesson on filtration, . 280, 281, 288 
Sarokin on creatinine, . ‘ 100 
Schabad on diabetes, 922 
Schaer on saliva, . 346 

Schifer and Bohm. See Bohm. 

Schafer on blood, . : ; - Hae 
Ay ee coagulation, POU GS HL 7D AD 

»,»  », fatabsorption, . 450, 457, 458 
ee; fibrin; - : : : te REG/, 

»» 9) gastric secretion, . 540 

»» 4, loternal secretions, 937 

3: 9»; metabolism, 868 

»> >, milk secretion, 662 

+) +, Oncometer, . 643 

», 3; Oxalated blood, 135, 147 

+> 3) pituitary extract, . 946 

ae 35) proteids, 42 

s» >, reaction of blood, . 144 

» », red corpuscles, . 155, 188, 189 

>> », Salivary glands, . 524, 525, 930 

9 9 Spleen, : : 960 

3: >, Suprarenal body, . : 90, 91 

eae as 7 extract, 950, 951, 959 

32 > bliyius, : : . 960 

>» 9», thyroid juice, . 943 

+» 33 White blood corpuscles, 83, 158 
Schaffer on intestinal secretion, se dot 
Schalfijew on hemin, 252, 253 
Schardinger on lactic acid, sadO7 
Scharling on calorimetry, 844, 846 
5 ,, heat production, . 838, 847 

ye », Tespiration, 695, 708, 715, 722, 
725, 726 

Scheel on foetal respiration, . : 731 
Scheele on respiration of ee 739 
>» uric acid, : 586 
Scheffer on diffusion, 263 
Scheibe on milk, 128 
Scheibler on cane-sugar, 10 


£029 

PAGE 

Scheibler on dextrin, . ; : Aan i} 
», Taffinose, . : : ; 12 

Schenck on bile salts, . : : . 9378 
3 - glycogen, - 919 


», glycolytic action of blood, 161 
Scheremetjew ski on respiratory exchange, 699 


Scherer on blood plasma, . 160 
35 ;, fuscin, : : ‘ « 121 

53 . inosite, : - : . 105 

= ,, leucine, - ; ; . 423 

5 Se laver:.* : A ‘ « 86 

ae ;; muscle, : «. LO 105 

,, Nervous tissue, . 3 seLlG 

~ ;; Pancreas, . : : Phe tiv’ 

Pf ;; quadriurates, : ; . 588 

34 5» Spleen, , : r yy od 

rr 55 bLLyMUS, i; F A . 88 

ag j,uuhyroid, i : ; 5 tete. 

, tyrosine, . . 424 
Schermber g on muscular metabolism, . 913 
Scheube on diet, : : : estat 
Schierbach on ptyalin, - : . . 329 
7,SWeat, ih. A . 670, 671 

Schiff on body temperature, . 855, 856 
»» 5», Chordatympani, . : . 483 
bl Aoudextrins ‘ : 2 . 542 


»» 9, fat absorption, ; 
ss 9y,« Gastric fistula, ; ‘ eee 


Be Son gre PSecretions as : 2 AD, 
:> 3; Pettenkofer’s test, . : acy i | 
»» 3, pituitary body, 3 3 . 946 
»»  »9 ptyalin, : ; - . 330 
3: 3» red corpuscles, : : ee Al 
3» >, Salivary nerves, . : ; 482 
Fong sks nF secretion,. 490, 502, 523 
»» >, Skin varnishing, . S 728 
+> 3) Suecus entericus, . : 349, 398 
» 3, thyroid gland, 938, 939, 941, 942, 
943 

Schiffer on body temperature, . = S07 
siptyalint (cir: - 327 

Schindler on nuclein bases of thymus . 88 
», testis, - aye! 
Schlagenhauffen on cholesterin . sg ok 
», lecithin, F Bes 2A 

Schlesinger on ptyalin, : . 11329 
Schlosing on ammonia of urine, . - 586 
Schlossberger on milk, . ; - VOLT 
oF ;, muscle, E : Be Os 

;, lervous tissues, . EEG 

Schlossmann on milk esp : . 134 
Schmaltz on blood, - : . 148 
Schmelz on muscle glycogen, 104, 105 
Schmidt on ash-free albumin, - Sh ole. 
boli ,gibileyl et Sete)... 560s S65 

x Jp nap Salts an 392 

- ;, blood, 145, 153, 154, 155, 157, 
163, 166 

53 subse faSes, 773, 780 

; ,, body temperature, 803, 809, 866 

3 ;; Charcot’s crystals, J0ivO4 

ap 57 COI unine, he . 634 

5 , coagulation, 168, 170, yA Bia. 
179, 319, 334 

3 ,, eytoglobin, 3 68 

¥ ,, endosmotic equivalent, wQTA 

» ,, fat absorption, . 3 . 460 

Pe ;, ferments, . : . 320 

= ;, filtration, . 231, 282, 283 

“3 >> gas pump, . : : Sey 


1030 

PAGE 
Schmidt on gastric fistula, . iigited 
5 a ao>  julceseia405 350, 351, 352, 
353, 356, 538 
a », hemoglobin, 195, 198, "206, 230, 
231, 244 
sf ., manition, . 3 : - 889 
a ;, intestinal secretion, . ceuDao 
ae ,, lungs, : ; ‘ ell 
EA ;, mucus, : > ; . O44 
¢ IUSCI]ES ee 4 ¢ eyo? 
sp ,» pancreatic juice, 367, 368 
= 55 pepsin, 3 : - 332 
ee ;» peptone plasma, | : = elif 
re ;, proteids, . E : oe 
3 », proteolysis, : : . 323 
i ,, reducing substance of muscle, 110 
<3 :, Tenal epithelium, é . 653 
ba ,, respiration, 707, 718, 781 
ae 56 GEES ; = 347, 348 
Ps ;, secretory cells, . P . 938 
As PSE SGPSING, 00 : F zvavico9 
urobilin, 21622 
Schmidt-Miilheim on albumose in ‘blood, 439 
aE a 5» casein, - Rope ih 8) 
s az 5 coagulation, 5 ey 
=a e ,, leucine in digestion, 438 
+ oe 5» peptone in blood, 41, 439 
53 +: ,, proteid absorption, 434, 
437 
Schmidt-Schwedt on respiration, . 5, UR 
Schmiedeberg on absorption of iron, . 886 
ne », ammonia inurine, . 907 
a » chitin, : 75 

,, chondroitin - sulphuric 
acid, : By els 
55 55 chondro- mucoid, 5 eS 
Ns ., erystallised proteids, = pb2 
, Soterratins), % + BGO 
ai <3 elycuronic HCid. 2 5 
“ ., hippuric acid, 601, 893 
e. ,, internal respiration, = 4.182 
ar ;; Muscarine, é 60, 513 
+5) Salts Of dOGGsaP 4. a Gt) 
5, Spermatozoa, . snl 93 
Schmitz on gastric juice, . ; . 3864 
Schmdoger on lactose, . : sol ial, 
Schneider on milk secretion, 664 
Sch6ffer on blood gases, 154, 761, 763, 771 
5 leucine and tyrosine, . « ADS 
Schofield on bile pigments, . : . 383 
Scholkoff on blood, : ; ; . 148 
Schénbein on saliva, : : js a 46 
Sch6ndorff on metabolism, 903, 904, 906 
as >> osmosis, : ey 
35 ,, thyroid feeding, ‘ . 944 
;, urea in muscle, : LOS 
Schiénemann on pituitary body, : . 946 
Schotten on cholalic acid, . : . 380 
ce ,, fatty acids, F : OLS 
a ,», fellic acid, 373, 381 
Schottin on skin secretion, . sy OCL6i2 
35 5, testis, E “ 2 93 
Schoumaker on skin absor ption, : O90 


Schoumow-Simanowsky on gastric juice, 349, 
350, 359, 539 


Schreiber on animal heat, . : . 863 
Schreiner on Charcot’s crystals, . aes 
v. Schréder on diuresis, ; ; . 649 
oF »» muscle,. - 908 
ee »» urea, 103, 160, 562, 902, 906 


INDEX OF AUTHORS. 


PAGE 
v. Schréder on uric acid, .. : . 909 
Schrodt on milk, 5 : . aie 
Schroff on eae heat, f 4 . 859 
Schréter on milk, : : : . 138 
Schrétter on caisson disease, S 5) 74 
Schuchardt on septicine, . : 20859 
Schultz on respiration, : : . 704 
Schultze on burns, ‘ : : es 
i‘. ,, fat production, . : 1932 
a ;, glow-worm, ; ; > a0 
5 », hemoglobin, . : . 194 
ne ,», respiration, ; : -/ ee 
as 59 UIC acids ae ; Apes }f)-! 
, wool fat, . ote! 
Schultzen on amido-acids in blood, . 899 
5 ,, sarcolactic acid in urine, . 616 
Schulz on proteids, : : - 26 
+> 9) Tespiration, 695, 703, 710 
Schulze on arginine, : 33 
* 5, aspartic acid, : ; : ee 
a 5, cholesterin, ‘ ; js. 
3 jt age ; ; : 1omek7 
is ;; fish slime, . : ; = (676 
3; ;, hemicellulose, . : wins 
. ;, lecithin, . 2 21 
ns ;, leucine, 29, 422, 
<5 ;; Muscarine, . é : 
- »» paracasein, . - : - 
+5 »» proteoses, . z : - Peo 
sis 5, ptyalin, ‘i F 3 - 329 
a ,, Starch digestion, . . 893 
a 5 wool fat.%. 2 ‘ : = (675 
Schumberg on rennin, . : . 334 
Schunck on phy lloporphy rin, : . 882 
Schuster on heat regulation, . . SOL 
Schutz on fetal respiration, : : Aged 
», zymolysis, . 322 
Schutz-Schultzerstein on alkalinity of 
blood, : ‘ : = plat 
Schiitzenberger on : gelatin, 47, 70, 71 
4; an hemoglobin, : «2201 
<3 ,, leucine and tyrosine, 425 
6 5, proteids, 26, 30, 31, 32, 
35, 36, 38, 403 
Schwalbe on bile secretion, . : 560 
55 Lutein: mae. : 5820 
Schwann on blood corpuscles, 2 E88 
x 55 PePSLDSaee : : . 402 
BS », respiration, : : .. 134 
»> saliva, . 327, 489 
Schwartz on elastin, hy 
33 respiration, : : +s) f3 
Schwarz on thyroidectomy, . : . 642 
Schwarzer on starch digestion, . . 393 
Schweigger-Seidel on lymphatics, . - 300 
Schwenke on blood heat, . : eel. 
Sciolla on skin absorption, . : - 687 
Sclater on temperature of snake, . 793, 849 
Scoresby on body temperature, . =o: 
Scudamore on blood gases, . : . 758 
a> ates) oleate 827 
Sezelkow on blood gases, 154, 761, 763, 764 
Ee Pr muscle, . 841, 911 
Ac 5, respiration, 699, 841 
Sebelien on caseinogen, 136, 137 
A ;, colostrum, . 3 4 wi Qe 
- ;, lactalbumin, . : L Se 
ais ,, lacto-globulin, . 3 . 139 
5 », milk, : ; : 3) i268 


Ap »» proteids, 41, 46 


INDEX OF AUTHORS. 


PAGE 

Seegen on carbohydrates, 919, 921 
45 5, dextrose, 914, 923 

5p », glycogen, . : F oo O94 

- », glycogenesis, F . 923, 926 
5 ae glycoly tic ferment of blood, 161 

Ag », Invert sugar, a . 398 

oF o respiration, é 695, 700 
ei ;, starch digestion, . é . 394 

“ », sugar in blood, 158, 159 

» oo» urine, 608, 609 

Seeman ‘ on lime in food, é . 886 
Seguin on respiration, . 712, 715, 725, 726, 
736, 739, 754 

Seitler on muscle, i ‘ ; se08 
Seligsohn on suprarenals, . ‘ A 6g) 
Selmi on animal alkaloids, . : 5 Be 
Semon on animal heat, 790, 866 
ae 5y bhyroid sland, ; . 942 
Senator on creatinine, . F F . 600 
Pa diuretics, . é . 648 

Bo. gy beat production, i . 847 

Aa ;, Manition, . : é a eis 

ee aeiudoxy!, 607, 627 


»» 3, respiration, a STi, alate als 


>> >, Secretion of urine, : G59 
,, Skin varnishing, . - 2+ a 428 
Senebier on respiration, 5 . 748 


Sertoli on blood gases, 157, 772, 773 
»» 95 Phosphoric acid of blood, LS 
aes. Saliva, . é é ; . 342 
Pei ss, BESLIS;« : 3 aiweos 

Setschenow on blood gases, 759, 761, 762, 

765, 766, 769, 770, 771, 773 


Peete. ; . 180 
Seume on body temperatur oH : . 867 
Sewall on gastric secretion, 531, 532 
Shepard on blood plasma, . : . 160 
Sherrington on blood, . 3 : . 148 
M ;, cerebral circulation, . 808 
Sb ,, eosinophil granules, . 84 
,, white corpuscles, . 5 LG? 
Shore on albumose absorption, . . 439 
4 eg Laos ; : - el'82 
3. >) peptone in blood, : : . 440 
>, 3, Smallintestine, . : . 399 
Sieber on bilirubin, 384, 389 
>> >» Cheese, . : 3 : - 933 
 eACISCI, . . ‘ : 2 RAE 
es gastric j juice, ; s . 364 
Peeeeeiematin: «5 : +1 250 
ee ree hematoporphyrin, : ZOD 
>> 3, hemoglobin, 207, 232 
a intestinal bacteria, : os 420 
5)», reaction of intestinal con- 
tents, a : . 464 
ae Teichmann’s crystals, 232, 252, 253 
», urorosein, . . 628 


Siedamgrotzky on body temperatur e, 790, 803, 
805, 807, 809, sl 


Siegfried on carnic acid, Die 103, 104 


Ap », conglutin, : : a moo 

», glutamic acid, . : . 426 

a. ,, lysine, 2 ; : :. 426 

c ;, muscle, . 106, 420 

5 5 nucleon, p 57 ue 

Ay) - pseudo-hiemoglobin, . pe e2By/ 

,, reticulin, 32, (2 

Sigalas on respiration, : 698, 700 


Silbermann on coagulation, . 174 
53 33 heat value, $33, 834 


1031 

PAGE 

Simon on blood plasma, , : erl6d 

5» 5, body temperature, Re O2o Our 

5s AWG cailhe. peleeien 4 2) 130 

ae thyroid body, ; F « 945 

»> », uroerythrin, . : F Oze 

Simony on bilifuscin, . ; - . 387 

de Sinéty on milk secretion, . . 663 
Singleton on body temperature, . 790, 811 

Sisel on hibernation, . 3 ‘ a (SD 

Sjoqvist on antipeptone, ; : . 421 

5 55) LESUMIC) jUICe,) 7 : . 3865 

a Sued, « . 584 

Skrebitzki on pancr eatic secretion, . 368 

Slosse on respiratory exchange, . Beal) 

Smirnow on salivary ducts, . : . 488 

Smith, A., on respiration, . 742 
ae E., on respiration, 698, 712, 716, (alte 
718, 721 

39 F., on sweat, . . 5 (Oa 

on ime on blood gases, 768, 776, 778, 779 

Bf 5 respiration, 739, 742 

ae ,, thyroid gland, , 943 

36 », thyroidectomy, . . 941 

»  M‘G., on ptyalin, *: F . 3829 

ee », snake venom, . 6) ae 

», uric acid, ; _ bey 

Snell on caisson disease, ‘ . 7187, 738 

Snow on asphyxia, - : . 744 

vy. Sobieranski on renal secretion, : . 654 

,, skin absorption, . 690 

Socin on iron of food, . : 3 CoD 

See. salesios food, ; . 883, 886 

Socoloff on bile salts, . ; ‘ oS 

Soemmering on lymphatics, . : . 803 

Solberg on milk, . : : : . 130 

Séldner on milk, . : . 126, 128, 130 

+5 ,, caseate of lime, . ‘ . 1386 

Solera on sulphocyanate of saliva, . 345 

Solin on glycogen, c : : 917 

Solley on gelatin, 47, 71, 429, 430 

Somerfeld on bile, ; A F a) ee) 

Sondén on inanition, . Soi 

Ap >, muscular metabolism, . : . 913 

+> 9, Yespiratory exchange, >) fils 

Sonnerat on body temper ature, . TL POLG 

Sorby on blood, . . 187, 209 

Sorensen on foetal respiration, é 5 ae 

Soret on blood spectrum, 225, 226 

Sotnitschewsky on glycogen, - sms yltD 

Br ney Jere . : ce 

SC DUNES . 5 7s 

Souleyet on body temperature, . J oz 

Soulier on skin absorption, . : . 686 

Sourdat on milk, . : « 128 

Souze-Leite on pituitary body Ait , ee 

Soxhlet on caseate of lime, . ‘ . 136 

pr ;, emulsions, . ‘ : . 447 

i , fat production, . : 932 

Deh pomnille 130, 131 

816, 823 


Spallanzani on animal heat, 


as », gastric digestion, . 364, ae 
,, hibernation, ; . (94 


701, 702, 723, 
739, 757, 781, 782 
Speck on blood gases, . 715 

body temperature, 807,. 808, 818 
muscular metabolism « JOG 
698, 708, 712, 716, 719, 
721, 738, 740, 748, 755 


53 ,», respiration, 


39 9? 


a9 9? 
»> 99 Tespiration, 


1032 


Spiess on heat production, 

+> 9) Salivary glands, 
Spilker on uric acid, 
Spina on skin glands, 
Spiro on bile, 

29 23 39 salts, 

A ee lactic acid in blood, 

», lymph, 

5» 55 sarcolactic acid, 
Spitzer on diabetes, 

err elycolysis i in blood, 
Spong on bile, 
Squire on body temperature, 
Ssubotin on fat, : 

= ;, milk, 
Stiadeler on bile pigments, 
bilifuscin, 
biliverdin, 
leucine, 
liver, . 
, nervous tissues, 
pancreas, 
spleen, 
spongin, 
thymus, 
thyroid, 
torpedo organ, 
urea, . 
Stiidelman on bile, 
55 te bilirubin, 

diabetes, 


Fe} 9: 


2? 39 


+B) 33 


be) 33? 
92 23 


3) 33 


ap suprarenal body, 


560, 561, 562 


pancreatic digestion, 
proteinchromogen, . 


Stadthagen on alkaloids in urine, 


25 5, leukzemia, 
55 % putrescine, 
Staffel on muscle, 
Stahel on thyroid g gland, 
Starke on proteids, - 
Starling on absorption, 


a ,, diuretics, . 
b. ;, lymph, : 
5 », osmotic pressure, 
5 », proteids, 
;, secretion of urine, 
Stefan on diffusion, 
Steiger on arginine, 
Stein on gastric juice, 
Steiner on emulsions, 
Steinhaus on mammary cells, 


Stenhouse on Pettenkofer’s test, 


Stern on body temperature, . 
ep 8», Gextroses 

5 35, reducing power, 

»> 3, removal of liver, 
Sternberg on notochord, 
Stevens on gastric digestion, 
Stewart on body heat, 

Stieda on pituitary body, 
Stierlin on blood corpuscles, 
Stillmark on ricin, 
Stockman on fasting, 

3 ;; imanition, 

me ,, iron in food, 
Stohmann on heat values, . 
Stokes on blood spectrum, 208 

ss 5, hemoglobin, 
Stoklasa on lecithin, 


285, 290 


402, 


, 229, 
230, 


PAGE 


594, 


664, 
128, 
382, 


33, 
567, 


29, 
29, 


843 
516 
595 
681 
562 
392 
159 
182 
106 
929 
161 


804 
933 
130 
384 
387 
385 
425 


303, 304, 305, 307, 


309 
648 
295 


272, 808 


536, 
829, 


78, 
834, 
251, 
243, 


41 
639 
262 

33 
B59 
445 
667 
377 
821 

7 
908 
113 
537 
851 
946 
151 

55 
888 
891 
884 
874 
254 
766 

21 


INDEX OF AUTHORS. 


PAGE 

Stoklasa on proteid food, 878 
Stokvis on muscular energy, 915 
5, urinary pigments, 625, 627 
Stolnikoff on fat formation, . 902, 934 
», fatty acids of liver, . 936 

Storch on fat formation, 902, 934 
Stourbe on skin absorption, . . 687 
Strassburg on blood gases, Nigel 7 
R », hemoglobin, . : EO. 

gs », hydrocele fluid, } . 784 

if ,, lymph gases, . 783 
Strassmann on alcohol, 882 
Straus on reaction of blood, . 145 
Strecker on bile acids, 378, 374, 376, 380 
as ;, blood plasma, : . 160 

5 ,, body temperature, 790, 803 

sf ,, fatty acids, . 454 

i ,, lecithin, i a 27) 

sy ;, nervous tissues, . ahs 

;, Xanthine, . . 596 

Stricker on milk secretion, 665, 666 
3 », saliva, . 346 

“ >» skin clands, : 681 
Stroganow on respiratory exchange, 694, 695 
Str ohmer on fat formation, . . ; uge2 
AA », respiratory exghaneyy OLS 
Struckmann on milk, : 130 
Struve on peptone in blood, . iutnal 
Stuart on body temperature, 789, 799, 805, 
809, 824 

Studemund on diet, . 877 
Stumpf on fat of milk, 664 
Stutzer on pepsin, 333 
3, saliva, 328 
Sundber g¢ on pepsin, 316, 328 
Sundwik on chitin, 74 
Suter on proteids, 26 
Sutton on body temperature, 866 
Swiecicki on pepsin, 330 
Sylvius on digestion, 401 


Szabo on acid of gastric juice, . 93804, 365 
Szigeti on cyanhematin, ; 

Szontagh on caseinogen, 139 
Szymonowicz on suprarenal extract, 951, 955 


TACKE on gases of alimentar y canal, 701 
Taddei on gluten, 5 : 53 
Tafel on sugars, . ; : d : 9 
Tambach on thyroid, é ; : ys 
Tamman on blood salts, : 157 
>» ~~, AVeezing point of solutions, 269, 

272 

rr », osmosis, 272, 274 

ss 9) Semipermeable membranes, 264 
Tangl on animal heat, 864 
,,  Tespiratory exchange, 719 
Tanszk on caisson disease, 737 
Tappeiner on absorption of bile salts, 392 
A ;, burns, : é 728 

es a cellulose, . 471 

3 », gases of alimentary canal, 729 

53 ;; gastric absorption, 432 

>, urea, 33 
Tarchanoff on bile, 567 
ae seis ‘pigments, 389 

», electrical currents, . 682 

Tar ulli on muscular metabolism, 913 


130 
821 
866 


Tatlock on milk, i : : 129, 
Tay on body heat, : 3 
Taylor on body temperature, 


— 


INDEX OF AUTHORS. 1033 


PAGE PAGE 
Tebb on small intestine, ; 4 . 899 Tizzoni on suprarenals, ; . 948, 949 
Teichmann on fat absorption, . 458, 459 5, 5, thyroidectomy, . . 939, 941 
», Pigeons’ milk, ‘ . 676 | Toepfer on hydrochloric acid, ; . 366 
Tenner on body temperature, . 855, 856 | Tollens on carbohydrates, . : 2, 612 
Thackrah on vital capacity, . : 751 | Tolmatscheff on milk, . 4 : . 128 
y. Thanhoffer on fat absorption, . . 450 | Tolputt on skin glands, ‘ : . 684 
Thénard on bile, . : E : . 372 | Tomes on enamel, ; F : eee likey 
Theodor on respiration, 707, 711, 848 | Tominaga on inanition, : , . 890 
Thiel on phloridzin diabetes, : . 921 | Tomsa on lymph production, 3 . 289 
Thierfelder on animal gum, . ; “i, EL24 Torup on hemoglobin, . 3 : oe Tike 
5 eF bacterial digestion, 398, 465 | Tourton on sweat, 5 al 
FS ,, body temperature, . . 800 | Tranbe on semipermeable membranes, . 264, 
is >, casein, . : ; . 140 273 
S », cerebrins, . 3 . 120 | Traube-Mengarini on skin absorption, . 689 
+3 », galactose, . 3 - 7 | Treskin on testis, . 2 ; : 562193 
os », glycuronic acid, . 2 5 Treviranus on respiration, . 701, 702, 709 
= ,, intestinal bacteria, ae Ae 3 ,, sulphocyanate of saliva,. 345 
is Reem, |. F : . 665 | Trimen on hibernation, ; ; 2 104: 
5 ;, reducing substance of Tripier on animal heat, ; : 4 aS 
mamma, . : 124 Triimpy on sweat, : . 671, 680 
Thiroloix on diabetes, . ; 928, 929 | Tscherewkow on absorption, : - 305 
Thiry on succus entericus, 368, 369, 398, 555, x », diastatic ferment of 
556 blood, . Fe plG 
Tholozan on body temperature, . . 855 | Tschermak on amyloid substance, ty(intA! 
Thoma on hemacytometer, . .- . 150 | Tscherwinsky on fat formation, . 932 
Thomas on body temperature, . . 867 | Tscheschichin on body heat, "921, 822, 841, 
= ,, cholesterin, 4 : . 564 858, 862, 863 
a », hemacytometer, : . 150 | Tschiriew on blood gases, . . 762 
;, urinary secretion, : . 639 A », lymph, . 780, 783 
Thomsen on ‘‘avidity law,”. 357, 358, 361 #3 », proteid metabolism, . 5 tele 
;, coeflicient of distribution, . 355 ae ,», Salivary secretion, . . 492 
Thomson on body temperature, . . 812 | Tschirwinsky on glycerin, . : . 8&2 
ss +» gastric juice, . 4 . 3852 | Tschlenoffon urea, . : : - 585 
Gs ,, vital capacity, . : . 751 | Tubby on suceus entericus, . 9341, 369, 399 
Thorner on milk, . : 5 PAG i> bos venous absorption, : . 3803 
Thornley on body temperature, : . 813 | Tucsek on inanition, . ; =) oll 
Thudichum on bilirubin, . . 384, 389 | Tuezek on salivary secretion, : . 491 
e ;, biliverdin, . ; . 385 | Tunnicliffe on piperidine, . : 5) RY 
As 5, kephalines, . Bs LTO 20 
¥ lutein. : : 20,95 | v. UpRANSKY, on cadaverine, . 5 BE 
ae ,, Phrenosine, . 3 fe 120 5 », Pettenkofer’s test, . 377 
x ;, urochrome, . . 618, 619 =r », ptomaines, . . 466 
s uroerythrin, f ; « 625 35 - putrescine, , 60 
Thuiller on reaction of blood, i pales », urine, 61, 609, 613, 626 
Tidy on milk, . E 2 E27 128 Uffelmann on collagen, 0429, 
Tiedemann on absorption, . 3 243i aa is Gleb; ; é 3 ott 
os ,, bile pigments, : . 382 >) 9a GaStric fistula, : . 537 
35 ,, blood gases, . : 5 VEE eats lactic acid, yas . . 366 
3 ,, body temperature,. 791,793 | Ughetti on thyroidectomy, 3 : . 942 
- », gastric secretion, . 352, 536, Ulrich on leucine in urine, . : . 602 
540 32 99 Wool fat, , ; F 5 (Os 
“ ,, lymph absorption, . . 803 | Umber on uric acid, F : - 67, 594 
= ., pancreatic secretion, . 3868 | Urbain on blood gases,. ; - 162, 763 
a a Saliva, +. ‘ . 9345, 348 +> 9) Yespiration, . 5 . 714, 748 
», tryptophan, . - . 427 | Urich on sebaceous secretions, . = 675 
Tiegel ‘on blood proteids, . . : . 162 | Uschinsky on diabetes, : - 922 
>>», metabolism, . : . 915 | Ustimowitsch on renal circulation, . 642 
v. Tieghem on temperature of plants, . 849 
Tigerstedt on filtration, . 280, 281, 283 | VauHLAN on cholalic acid, . ; -- 380 
- ;; heat value, : : . 875 | Vaillard on tetanus toxin, . : OS 
s ,; Imanition, ‘ ; . 891 | Valenciennes on body heat, : . 849 
a ;, lymph production, . 4 289 35) Ichthins : 5 ie 
o », muscular metabolism, . 913 Valentin on body temperature, 793, 840, 867 
», respiratory exchange, . 718 59 ,, electrical currents, . - 682 
Tilanus on elastin, : 3 : syed 3 », hibernation, . : = 498 
, horn, . : ate 53 >> muscle, .. F P 911 
Tillet on "body temperature, . ; . 814 » 9) respiration, 694, 725, 727, 744, 
Tissandier on respiration, . - 738 781 
Tissot on respiration, . ; 782, 841, 911 >> 5, Skin currents, . 682 


Tizzoni on proteid food, : ; . 878 So | Gae Gs varnishing: : s RAT 


1034 
PAGE 
Valentiner on bilirubin, s : . 382 
Valentowicz on milk secretion, . . (6638 
Van de Velden on gastric juice, 330, 355, 
545 
Vanlair on stercobilin, . 2 . 388, 474 
Vas on thyroid feeding, : > . 944 
Vasale on parathyroids, : on 940579411 
°, ‘5; Pibuitary body,” = . 945, 946 
+> 3; Sebaceous glands, . : . 674 
»» : thyroidectomy, . ; . 942 
Vassiliew on pancreatic enzymes, . . 336 
af fistula, . OO 
Vaudin on "colostrum, : ; : 5 Ue) 
yo) * sp mn keer ; : : 130 
Vaughan on ptomaines, . 58, 59 
Vauquelin on respiration, 701, 702, 704 
Vay on iron in liver, . : oF take 
Velich on suprar enal extract, negoil 
Vella on succus entericus, 368, 397 , 398, 555 
Velten on animal heat, : : . 841 
Veragutt on urea, : : . . 585 
Verdeil on. blood, . 77, 160 
Vermehren on thyroid feeding, : . 944 
Vernet on body temperature, : . 807 
Vernois on milk, X . 128, 180, 131 


Vernon on respiration,. 699, 701, 702, 703, 


711 

Viault on red corpuscles, . : a '50 
Vierordt on blood corpuscles, ; 5 Me 
55 +> oe Spectrum: 209, 213 

o ,, body heat, 837, 838, 850, 851, 852 

“ », osmosis, . 21273 

sf - reduced hemoglobin, . ~ 231, 234 


reducing power of tissues, . 782 


34 : respiration, 698, 711, 712, 715, 

(PAS Het 749, 755 
* », rickets, : : . 886 
7. ,, skin absorption, : 5 (ats 


spectrophotometry, 214, 215, 216, 
218, 219, 220, 221, 222 


22 29 


Vignal on bile secretion, : 5 OY, 
Vignon on fibrin, ; - : x a8 
Ville on biliary fistula, : : . 460 


5, fat absorption, : : . 460 


9° 


Vincent on paired bodies, 957; 959 
i, ,, suprarenal extract, . SF Yall 

e ;; suprarenals, : : ~ 192 

a >, thymus,  . : : . 960 
Vines on aleuron grains, 5 : 7 Palh52 
a5 ne proteoses, ; ‘ : 51 
5, 5, temperature of plants, . . 849 
Viola on pituitary body, . é - 946 
Virchow on adipocere, . : tina20 
. ,, amyloid substance, 5 : 74 

i, ,, body temperature, . . $818 

i ,, hematoidin, 260, 384 

53 , leucine, . 5 5 omn421 

», Pancreas, . : : 5 

Vogel on animal heat, . : : . 846 
>> >», blood gases, . : : 20758 
ee ae calorimetry, : , ‘ . 846 
ee ISOMmaltOSe.) jae , ; ite og WE 
Pa ee lactose,). : : ‘ 5 O99 
Me iaroses, i: ‘ : : ‘ 7 
fess eelycoren, . ; : 15, 397 
EE clycorenesis, .. f ‘ = .926 
Pepe pentose, . d ; : 3 
»> >» quadriurates, . Z ‘ . 588 
>>») Starch digestion, . : 5 ay 


», succus entericus, . : . 398 


INDEX OF AUTHORS. 


PAGE 

Vogelius on glycogen, . ; : . 919 
Voigtliinder on diffusion, . : . 263 
Voit on acid of gastric juice, 4 . 358 
»> >», adipocere, : ‘ : +) 983 
ew acolo lamer : : . 882 
55) 55, almido-acids-yar. , 3 . 880 
+> >, ammonia inurine, . - 907 
> >», balance of nutrition, 871, 872, 873 


5» >, biliary fistula, . E é . 460 
»» 3, blood plasma, . : i . 160 
>> >> creatine in muscle, . ‘ «S800 


os diet, : ae 876, 877, 878, 891 
ik fesces: f >. 442 

Pen Lau absorption, . : . 454 
ahrsedccs ee 664, 932, 933, 934, 935 
55) apeeelanims 878, 879 
+ ele glycogen, 15, 917, 918 
»> »» glycosuria, 5 s 5 . 881 
»> >, heat regulation, i 5. oS 
s> >, Mmanition, 887, 889, 890, 891 
>> >> imtestinal secretion, . ‘ - 1656 
53 1, ptlactose; fee é : F . 399 
s> > lime in food, 635, 886 
5) 53. MUSCle, we x 3 100 
at muscular metabolism, 3 joO12 


ss 3, proteid absorption, . : . 4386 
Hn 5. oods - 876, 892, 894 
»> 3x» proteids, 896, 897, 898, 903 
»> ») respiration, 696, 700, 707, 708, 712, 

716, 718, 721, 755, 781, 803, 848 


», skin absorption, - 688 
Volhard on urine, é . 634 
Voorhees on wheat proteids, | : on egree: 
de Vries onisotony, . ; - 142 

;, osmotic pressure, ; -| 270 

Vi ulpian on chorda tympani, ; . 520 
a ;, skin secretion, 673, 677 

of ,, Suprarenal body, 90, 91 

a 5, Sweat, 678, 679 
WAAMPELMEYER on bone, . ; 5 alg} 
Waddell on abrin, F : 5 5 DD 
Wagner on carnine, 3 é .. LOZ 
+ »» respiratory exchange, . Shey //ila) 


. ,, thyroidectomy, . , » 939 
Wagstaffe on spinal injury, . ; . 861 
Walden on semipermeable membranes, 264, 


275 

Waldenburg on residual air, . : 5750) 
Waldeyer on thyroid gland, . : . 945 
Walker on lactic acid, : alos, 
Wall on snake venom, . : «= D6 
Waller on body temperature, 830, 852, 855 
Suns, Calorimetiyer. 5 3 . 846 

yg ge hedrt, WOLKS i ; . 843 


> skin absorption, ? J . 689 
Walter on alkalinity of blood, . lto 


»» 35 blood gases, Hols 42 

5S PaaS eS salts 2 ‘ isso 

», ichthulin, . ‘ =), e164: 

v. Walther on animal heat, 820, 822, 823 
is ,, fat absorption, 450, 462 
Wanklyn on butter, . : : a 33 
Warden on abrin, : : » .55 
Warren on acidity of muscle, : - 108 


ss ,, body temperature, 735, 850, 865 

»> 95 respiratory exchange, . » ie 
Warrington on bacteria in urine, . . 583 
Warter on body temperature, : . 821 
Washbourn on body temperature, . 790 


INDEX OF AUTHORS. 


; PAGE 
Washbourn on calorimetry, . 844, 845 
Wassilieff on pancreatic secretion, 554 
Wassmann on gastric juice, . : . 534 
Watson on ptyalin, : ; . 829 
Waurinski on peptonisation, P . 333 
Weber on diffusion, ; : : . 263 

5» 5) foetal respiration, . ‘ i628 
>>», imdicanuria, . ; : 2 (Bil 

oe ., Serum, .. 3 ; ‘ Fels 

ay Sweat, . ; 067031678 
Weckerling on body temperature, . 820 
Wedensky on salivary secretion, . . 493 
5, urine, : . 609, 613 
Wegscheider on feces, . : : . 473 
Weidel on carnine, ; : : eek? 
ant, Xanthin, 4 F ‘ 259s 
Weidenbaum on glycogen, . : a les 
Weigelin on body heat, : : . 802 
Weiland on body temperature, . a 822, 
Wein on milk fat, , : SS 
Weinmann on pancreatic juice, : . 547 
Weintraud on caseinogen, . > dey 
53 . phosphates of nen! Oo? 

ae ;» uric acid, : 67, 594, 595 

;, xanthin, : : 5 th 

Weisbach on nervous tissues, - ) ShI5 
Weiske on amido-acids, z J . &80 
an ;, cellulose, F . 470, 881 
tad kk eyes, e181 
OO ccintituyaret, + 664 

Weiss o on bile salts, : , . 9392, 563 
i: ee glycogen, * . 105, 919 
>> >» lymph pressure, . : . 299 

s> +> Muscular metabolism, . =) SOD 
3) 9) pancreatic secretion, B 6 YL 
+>», red corpuscles, : ; Sela! 

, trypsin, : - : . 338 

Welcker on blood, . 141, 149 
Welitschkowsky on respiration, : . 740 
Wells on body temperature, : of ol 
s> », red corpuscles, : - . 188 
Wendelstadt on thyroid feeding, . . 944 
Wendt on Harderian gland, . : > 675 
Wenz on albumoses, . . 2 4d 
+> >» intestinal enzymes, : 5) OAL 

+: 99 proteids, : : ; 5 ED 
Werigo onalbumin, . 3 : - 25 
- ,, blood gases, : 3 5 HS 
Wertheim on burns, . e128 
5, respiratory exchange, . 698 
Wertheimer on bile, . 560, 565 
- > 95 pigmen nts, : . 564 

5 ;, salivary secretion, . 524 
Werther on lactic acid, : ‘ - 109 
EA ,» rigor mortis, - 918 

Bs aA saliva, 344, 348, 488, 494, 499, 
500, 527 

Wesbrook on succus entericus, . 554 
Wetherill on adipocere, : : = — 20 
Weydemann on proteids,. - > GD 
Weyl] on CO-methemoglobin, ‘ - 249 
ss 95 creatinine, : 4 . 599 

3> 95 crystalline proteids, : se 
eons, muscle, . : . 108 
ED putrefaction, : ; ‘ . 467 
owa,, Sericin, . : : : 76 

, torpedo organ, 110, 111 

White on body temperature, 790, 821, "824, 
830, 839, 852, 858, 864 

a> calorimetry, . 844, 845 


1035 

PAGE 

White on hibernation, . 795, 796, 797, 866 
9» 9) levulose, : - ~ GLE 

,, thyroid gland, 89, 938 
Whitehouse on copper albuminate, 26 
Whitfield on nucleo-proteid of muscle, 97, 98 
Whitwell on thyroidectomy, ; ‘941 
Wiedemann on biuret, . , : . 48 
AS ae electro- -osmose,  . . 688 
Wiemar on fat absorption, . : . 458 
Wiener on respiration, . : : Bh ek 
Wildenow on caseinogen,  . : Ac PAB 
os 3 dyspeptone, 2 : . 429 
Wildenstein on milk, . : ‘ PEt 
Wilks on body temper ature, ; . 866 
Will on fat absorption, . 451, 452 
Williams on bile, . B . . 369 


ng 5 body temperature, 
Williamson on blood, . : : . 144 


Willis on animal heat, - ; : oon 
Winkler on oxygen of blood, 1 1665160 
Winogradoff on albumin, . : Saag 
Winston on bile, . : : 2 = (one 
Winteler on bile salts, . - 392 
Winternitz on alkalinity of blood, . 145 
e ,, hemoglobin, . : . 152 

e ,, proteids, P 49 

a ,, skin absorption, 686, 687 , 689, 

690 

Winterstein on chitin, . $ - ty a7! 
Wiskemann on fcetal blood, . : = 18H 
Wislicenus on chenocholic acid, . One 
35 », muscle, . ; 106 

», source of muscular energy, 912 

Wissel on bacterial digestion, : 464 
v. Wistinghausen on coagulation, 5 


,, fat absorption, . 461 


y. Wittich on digestive extracts, . 315, 316, 
328 

rP ,, enzymes, 317, 320, 337 

S ,, fat absorption, : . 461 

ee ,, glycogen, : . Be eal 

a .» lymph hearts, : . 301 

f », pancreatic diastase, . . 340 

- +> pepsin, 331, 404, 535, 535, 

542 

a ;, renal nerves, . : . 644 

- >> 9) secretion, ‘ - 653 

= a ysaliva. : Bs 

»> skin absorption, 686, 689 
Wittmaack on milk, . : : . 104 
Wittstein on fats, - : . see ty 
Wiladimiroff on isotony, ; ; Bee 
Wohler on hippuric acid, . : . 892 
san 4) 45 Urea, A 35, 581, 893 
Wolfenden on mucinogen, . : = Oe 
;, snake venoms, : = 56 

Wolff on pepsin, . - . - - 333 
Wolffberg on respiration, . oh bay has 
Wolkow on urine, 605, oe 607, 630 
Wolkowicz on proteids, , - 38 
Wollonmilk, . : 5 RE 
Wollowicz on ‘body temperature, - 820, 825 
Woltering on iron in liver, . . . 86 
Womack on body temperature, . - 866 
Wood on animal heat, . . 824, 844, 863 
|. XeESplrablonsar. : - a OT 
Woodman on hyperpyrexia, . : . 823 
Woods on heat value, . : 5) BB: 


Wooldridge on coagulation, . 37, 146, 173 
as ;, colloids, : . a eso 


1036 


PAGE 
Wooldridge on fibrinogen, 55, 68, 166, 176, 
178 
7 ,, peptone plasma, 174, 175 
,, red corpuscles, , eu IdD 
Worm-Miiller on glycosuria, : . 881 
os », hemoglobin, . 50 IG 
a4 sh nuclein, : : Sys 
,, starch, : : ei) 
Wortman on bacterial digestion, . . 470° | 
Wright on coagulation, 170, 178, 180 | 


Be (gt fibrinogen, 166, 175, 176, 177, 178 


= 3 @lycoven: ee --- 920 
+> 93 peptone plasma, . : : enL76 
Wroblewski on caseinogen, - : senso 


Wulff on alloxuric substances, 67, 597, 598 


Wiillner on osmotic pressure, : sat 2T2 | 


Wunderlich on body temperature, 786, 789, 
805, 809, 810, 812, 823, 825, 855 


Wurm on tetroner ythrin, . 21 
Wiirster on Adamkiewicz’s reaction, . 47 
oP ,, body temperature, . . 804 

bs », COsin urine, . : -) 634 

ee ,, hydrogen peroxide, . pated’ G 
Wurtz on choline, : : : yoln2i 
BS », papain, : : 51, 54 
iews>) pepsin: : : ; . 404 

2 », ureainlymph, . : ae alisy 
YEO on bile, 3 s37d 
5) >» reducing power ‘of tissues, J0n/82 
Yersin on diphtheria toxin, . : sONt8 
Young on bone, . : : 5 itil 
a a carbohydrates, ; : ay 42 

»> ») polysaccharides, . ‘ PLS 

% «55 Leuiculiminer : : Lae 

s> 95 Vitreous humour, . : 62, 123 
Yvon on cerebro-spinal fluid, c - 184 
by | G50 MLEIMeS ane : : : a ay/s) 
ZACKE on respiration, . : : eel 
Zahor on proteids, : : : . 41 
Zalesky on bile, . 5 : : . 560 


INDEX OF AUTHORS. 


| PAG 
Zalesky on bone, . : i 2 
3 3, hepatin, 69, 8¢ 
Fy >, ron in fetus, : : “niees 
i ,», proteids of diet, . 562, 908 
5 », Skin glands, y : . 673 
| Zalocostas on spongin, . : 5 at 
Zander on polysaccharides, . : 5 PAS 
Zawadski on pancreatic juice, ; . 368 


Zillesen on lactic acid in ae 
Zinoffsky on hemoglobin, 


ae hCs gases, Ji lae7 Ge "762, fas. 
764, 765, 770, 771, 772, 773, "78 
Ei aeebody: temperature, 


» 99 gases of alimentary canal, . 729 
5 9, Slycogen, . : : - 919 


Se a5 proteid metabolism, 5 = EG 
», respiration, 692 , 699, 701, 709, 711, 
718, 714, 716, 7 718,:719, 726, 
732, 733, 740, 747, 749, 750, 779 
Zweifel on amylopsin, . : - - 336 


y >, pepsin, <: : : . 330 
if », ptyalin, E i E . 327 
4 5, rennin, A ; J 334 


FP ;, Tespiration, 731, 732 


END OF VOL. I. 


Zawarykin on fat absorption, : - 450 
Zawilski on fat absorption, . - 462, 463 


», Water phate: F - 433 
| Z iegelroth on blood, . ate Yoaeas 
| Ziehl on fat absorption, ; : . 459 

Ziemke on gastric juice, ra 364 


895, 908 
27, 196, 201, 202 


#5 Pe oxyhaemoglobin, 199, 200 
Zoja on lecithin, . : F 92 
BAe uroerythrin, ; 5 3 ». 623 
Zumft on proteids, : é A . 467 
Zuntz ou amido-acids, . : : . 880 
»> 39 balance of nutrition, . 871 

3) 5s blood; 143, 144, 145, 151, 732 


820, 841, 842 
»» 53 CO-hemoglobin, . é 238 


» 9 glycogenesis, , : ne P2833 
>> 9»; glycosuria, . : 4 “1 0922 
C) oe} inanrtions as f : Spey 
a ess LULL See 754 


[ages muscular metabolism, 912, 913, 914 


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