IRLF
B M 1D7 nil
MEDICAL
Jodloal Library Bxohsngf
WORKS BY THE SAME AUTHOR:
Published ty D. Appleton & Company.
The Physiology Of Man ; designed to represent the Existing State
of Physiological Science as applied to the Functions of the Human
Body. Volume I., Introduction; Blood; Circulation; Kespiration.
1 vol., 8vo, cloth, pp. 500. Price $4.50.
The same, Vol. II., Alimentation ; Digestion ; Absorption ; Lymph and
Chyle. 1 vol., 8vo, cloth, pp.550. Price $4.50.
The same, Vol. III., Secretion; Excretion; Ductless Glands; Nutrition;-
Animal Heat; Movements; Voice and Speech. 1 vol., 8vo, cloth.
pp.520. Price $4.50.
The same, Vol. IV., The Nervous System. 1 vol., 8vo, cloth, pp. 470.
Price $4.50.
Recherches experimentales sur une nouvelle fonction du
foie, consistant dans la separation de la cholesterine du sang et son
61imination sous forme de stercorine (seroline de Boudet), Paris,
Germer Bailiere; and New York, D. Appleton & Company, 1868.
1 vol., 8vo. pp. 122. Price $0.75.
This work received an "Honorable Mention" with a "Recom-
pense" of 1,500 francs from the Institute of France (Academie des
Sciences), in 1869, Concours Montyon (Medecine et Ckirurgei).
On the Physiological Effects of Severe and Protracted Mus-
cular Exercise ; with special Eeference to its Influence upon the
Excretion of Nitrogen. 1871. 1 vol., Svo, cloth, pp.91. Price $2.00.
Manual of Chemical Examination of the Urine in Disease ;
with brief Directions for the Examination of the most common Va-
rieties of Urinary Calculi. -Third editton, 1872. 1 vol., 16mo, cloth,
pp. 76. Price $1.00% <•> Y\ , „ f
MEDICAL
HE LIBRARY,
PHYSIOLOG
tv,
pester,
DESIGNED TO REPRESENT
THE EXISTING STATE OF PHYSIOLOGICAL
SCIENCE,
AS APPLIED
TO THE FUNCTIONS OF THE HUMAN BODY.
BY
AUSTIN FLINT, JR., M.D.,
PSOFESSOB OF PHYSIOLOGY AND PHYSIOLOGICAL ANATOMY IN THE BELLEVUE HOSPITAL
MEDICAL COLLEGE. NEW YORK; ATTENDING PHYSICIAN TO THE BELLEVUE HOSPITAL;
CONSULTING PHYSICIAN FOB THE CLASS OF NEBVOU8 DISEASES TO THE BU-
BEAU OF MEDICAL AND 8UEGICAL BELIEF FOB OUT-DOOB POOB,
BELLEVCE HOSPITAL; FELLOW OF THE NEW YOBK ACADEMY
OF MEDICINE ; MEMBEB OF THE MEDICAL SOCIETY
OF THE COUNTY OF NEW YOBK, ETC., ETC.
NERVOUS SYSTEM.
NEW YOKK:
D. APPLETON AND COMPANY,
549 & 551 BROADWAY.
1873.
ENTERED, according to Act of Congress, in the year 1872,
BY D. APPLETON & CO.,
In the Office of the Librarian of Congress, at Washington.
PEEF ACE.
THERE is, probably, no subject connected with human
physiology, which has engaged the attention of experi-
mentalists and philosophic writers so much as the ner-
vous system, especially within the last few years. The
author has, from the first, looked upon this division of
the work as the most important and the most difficult of
all, and feels that this volume will be regarded with more
critical interest than any one of the series ; and if he has
succeeded, even in a measure, in giving, in it, a satisfac-
tory representation of our present positive knowledge, no
apology is necessary for the length of time occupied in
its preparation. For two and a half years, he has been
almost unremittingly engaged in writing this volume, and
has endeavored to overcome, rather than avoid, the diffi-
culties which have presented themselves in the investiga-
tion of important questions, which are as yet regarded by
many as unsettled.
A great part of the inevitable delay which has attend-
ed the publication of this part of the work has been due
to the difficulty in this country of consulting rare and im-
portant memoirs. "When it is stated that every citation
4 PREFACE.
has been made after a careful study of the original publi-
cation, any one acquainted with the literature of the ner-
vous system will appreciate the amount of labor involved
simply in bibliographical research ; but in this depart-
ment, more than in any other, it is necessary to avoid
taking experiments and opinions at second-hand. The
experience of many years, as an experimental physiolo-
gist and a practical teacher, has enabled the author to
verify many of the important facts stated in this volume,
and has led to some original observations, which appear
in the body of the work.
The present volume treats of the physiological anatomy
and the functions of the nervous system, as they appear
to a practical physiologist, accustomed to accept nothing
that is not capable of positive demonstration or well-sus-
tained inference. Adhering conscientiously to the posi-
tive method of study, the author has endeavored to pre-
sent an account of the nervous system, which, though it
will undoubtedly.be extended by future investigations, is
made up mainly of statements of facts that will probably
not undergo serious modification, as we advance in our
knowledge of the subject. He has considered the proper-
ties and functions of the cerebro-spinal and sympathetic
nervous systems, mainly from this point of view ; and has
touched but slightly upon psychology, which has long
been considered a science by itself. The special senses
have been deferred, to be taken up in the fifth and last
volume of the series.
The physiological anatomy of the nervous system is
regarded by the author as an indispensable preparation
for the study of its functions. The most reliable recent
PREFACE. 5
works upon histology contain, of course, much that is of
no great physiological interest or importance, and the best
anatomical treatises do not generally give a description
of parts with particular reference to their physiology. To
facilitate the thorough comprehension of the subject, the
author has carefully detailed certain anatomical points, a
familiarity with which is necessarily involved in an accu-
rate study of nervous physiology.
The publishers of this series, having lately issued
Prof. Hammond's treatise on Nervous Diseases, are de-
sirous of presenting a complete work on the "Physiology
and Pathology of the Nervous System." Both Prof. Ham-
mond and the author of this volume heartily concur in
this plan. Though the full consideration of the physiology
of the nervous system would perhaps be out of place in
a treatise on nervous diseases, a thorough knowledge of
its functions is none the less important as a preparation
for the intelligent study of its pathology. The present
volume was written as one of the series on the " Physi-
ology of Man," but will also be issued as the first vol-
ume of a complete work on the Physiology and Diseases
of the Nervous System. It is proper to state that the
two volumes thus published were written independently
of each other, and that Prof. Hammond is in nowise re-
sponsible for the author's views upon physiology, nor for
any errors or defects that may be found in his part of the
work. The reader, however, will find few points upon
which there is any radical or important difference of opin-
ion ; but where these differences occur, they have been
frankly stated, and each author is solely responsible for
his own opinions and statements.
6 PREFACE.
Finally, the author presents this volume, with the
simple statement that he has made an honest attempt
to compass the great subject to which it is devoted, the
magnitude and importance of which he never appreci-
ated so fully as at the present moment. In the prepara-
tion of this volume, it was expected to include in it the
special senses, and chapters upon touch, smell, and sight,
were written, so that at least one-fifth of the last volume
of the original series is already completed. The fifth vol-
ume is therefore so far advanced, that it is hoped that the
entire work will be finished within a year. The last part
will be devoted to the Special Senses and Generation.
NEW YORK, May, 1872.
O ON TEN TS.
CHAPTER I.
PHYSIOLOGICAL DIYISIONS AXD STBUCTrBE OF THE NEBVOUS SYSTEM.
General considerations — Divisions of the nervous system — Physiological anatomy
of the nervous tissue — Anatomical divisions of the nervous tissue — Medul-
lated nerve-fibres — Simple, or non-medullated nerve-fibres — Gelatinous
nerve-fibres (fibres of Remak) — Accessory anatomical elements of the
nerves — Branching and course of the nerves — Termination of the nerves
in the muscular tissue — Termination of the nerves in glands — Terminations
of the sensory nerves — Corpuscles of Pacini, or of Yater — Tactile corpus-
cles— Terminal bulbs — Structure of the nerve-centres — Nerve-cells — Con-
nection of the cells with the fibres and with each other — Accessory anatom-
ical elements of the nerve-ceutres — Composition of the nervous substance—-
Regeneration of the nervous tissue — Reunion of nerve-fibres, . Page 13
CHAPTER II.
MOTOE AND SEXSOBY XEBVES.
Distinct seat of the motor and sensory properties of the spinal nerves — Specu-
lations of Alexander Walker — Views of Sir Charles Bell regarding the func-
tions of the anterior and posterior roots of the spinal nerves — Experiments
of Magendie on the roots of the spinal nerves — Properties of the posterior
roots of the spinal nerves — Influence of the ganglia upon the nutrition of
the posterior roots — Properties of the anterior roots of the spinal nerves —
Recurrent sensibility — Mode of action of the motor nerves — Associated
movements — Mode of action of the sensory nerves — Sensation in amputated
members, 66
O CONTENTS.
CHAPTER III.
GENEBAL PEOPEETIE8 OF THE NEEVE8.
Nervous irritability — Different means employed for exciting the nerves — Disap-
pearance of the irritability of the motor and sensory nerves after exsection
— Nerve-force — Non-identity of nerve-force with electricity — Rapidity of
nervous conduction — Estimation of the duration of acts involving the nerve-
centres — Action of electricity upon the nerves — Contrasted action of the
direct and the inverse current on closing and opening the circuit — Voltaic
alternations — Induced muscular contraction — Galvanic current from the
exterior to the cut surface of a nerve — Effects' of a constant galvanic cur-
rent upon the nervous irritability — Electrotonus, anelectrotonus, and cathe-
lectrotonus — Neutral point — Negative variation, .... Page 91
CHAPTER IV.
SPINAL NEEVES — MOTOB NEBVES OF THE EYEBALL.
Special nerves coming from the spinal cord — Cranial nerves — Anatomical classi-
fication— Physiological classification — Motor oculi communis (third nerve)
— Physiological anatomy — Properties and functions — Influence upon cer-
tain muscles of the eyeball — Action of the inferior oblique muscle — Influ-
ence upon the movements of the iris — Patheticus, or trochlearis (fourth
nerve) — Physiological anatomy — Properties and functions — Action of the
superior oblique muscle — Motor oculi externus, or abducens (sixth nenre)
— Physiological anatomy — Properties and functions, . . .122
CHAPTER V.
MOTOB NEBVES OF THE FACE.
Nerve of mastication (the small, or motor root of the fifth) — Physiological anat-
omy— Deep origin — Distribution — Properties and functions of the nerve
of mastication — Facial nerve, or nerve of expression (the portio dura of the
seventh) — Physiological anatomy — Intermediary nerve of Wrisberg — De-
cussation of the fibres of origin of the facial — Alternate paralysis — Course
and distribution of the facial — Anastomoses with sensitive nerves — Summary
of the anastomoses and distribution of the facial — Properties and functions
of the facial — Functions of the branches of the facial within the aqueduct
of Fallopius — Functions of the chorda tympani — Influence of various
branches of the facial upon the movements of the palate and uvula — Func-
tions of the external branches of the facial, 139
CONTENTS. 9
CHAPTER VI.
SPINAL ACCESSOET AXD 8TJBLINGUAL NEBVES.
Spinal accessory nerve (third division of the eighth) — Physiological anatomy-
Properties and functions of the spinal accessory — Functions of the internal
branch from the spinal accessory to the pneumogastric — Influence of the
spinal accessory upon tlie vocal movements of the larynx — Influence of the
internal branch of the spinal accessory upon deglutition — Influence of the
spinal accessory upon the heart — Functions of the external, or. muscular
branch of the spinal accessory — Sublingual, or hypoglossal nexve (ninth) —
Physiological anatomy — Properties and functions of the sublingual — Glos-
so-labial paralysis, 166
CHAPTER VII.
TBIFACIAL, OE TBIGEMIXAL XEBVE.
Physiological anatomy of the trifacial— Properties and functions of the trifacial
— Division of the trifacial within the cranial cavity — Immediate effects of
division of the trifacial — Remote effects of division of the trifacial — Effects
of division of the trifacial upon the organs of special sense — Division of the
trifacial before and behind the ganglion of Gasser — Communication with
the sympathetic at the ganglion of Gasser — Explanation of the phenomena
of disordered nutrition after division of the trifacial — Cases of paralysis of
the trifacial in the human subject, 184
CHAPTER VIII.
PNEUMOGASTBIC, OE PAB VAGTJM NEBVE.
Pneumogastric nerve (second division of the eighth) — Physiological anatomy —
Properties and functions of the pneumogastric — General properties of the
roots — Properties and functions of the auricular nerves — Properties and
functions of the pharyngeal nerves — Properties and functions of the supe-
rior laryngeal nerves — Properties and functions of the inferior, or recurrent
laryngeal nerves — Properties and functions of the cardiac nerves, and influ-
ence of the pneumogastrics upon the circulation — Depressor-nerve of the
circulation — Properties and functions of the pulmonary branches, and influ-
ence of the pneumogastrics upon respiration — Properties and functions of
the cesophageal nerves — Properties and functions of the abdominal branches
— Influence of the pneumogastrics upon the liver — Influence of the pneumo-
gastrics upon the stomach and intestines — Summary of the distribution,
properties, and functions, of the pneumogastrics, .... 203
10 CONTENTS.
CHAPTER IX.
PHYSIOLOGICAL ANATOMY AND GENEBAL PEOPEETIES OF THE SPINAL
COED.
General arrangement of the cerebro-spiual axis — Membranes of the encephalon
and spinal cord — Cephalo-rachidian fluid — Physiological anatomy of the
spinal cord — Direction of the fibres after they have penetrated the cord by
the roots of the spinal nerves — General properties of the spinal cord —
Effects of stimulation applied directly to different portions of the
cord, Page 257
CHAPTER X.
ACTION OF THE SPINAL COED AS A CONDUCTOE.
Transmission of motor stimulus in the cord — Decussation of the motor conduct-
ors of the cord — Decussation at the medulla oblongata — Decussation of the
motor conductors in the cervical portion of the cord — Transmission of sen-
sory impressions in the cord — The white substance of the posterior columns
does not conduct sensory impressions — Action of the gray matter as a
conductor — Probable function of the cord in connection with muscular
coordination — Decussation of the sensory conductors of the cord — Summary
of the action.of the cord as a conductor, 279
CHAPTER XI.
ACTION OF THE SPINAL COED AS A NEEVE-CEXTEE.
Movements in decapitated animals — Definition and applications of the term
" reflex " — Reflex action of the spinal cord — History of the discovery of
so-called reflex action — Question of sensation and volition in frogs after
decapitation — Character of movements following irritation of the surface
in decapitated animals — Dispersion of impressions in the cord — Conditions
essential to the manifestation of reflex phenomena — Exaggeration of reflex
excitability by decapitation, poisoning with strychnine, etc. — Reflex phe-
nomena observed in the human subject, 298
CHAPTER XII.
THE CEEEBEAL HEMISPHEEES.
Physiological divisions of the encephalon — Weight of different parts of the
brain and of the entire encephalon — Some points in the physiological anat-
CONTEXTS. 11
orny of the encephalon and its connections — The cerebrum — General prop-
erties of the cerebrum — Functions of the cerebrum — Extirpation of the
cerebrum in animals — Pathological facts bearing upon the functions of
the cerebrum — Comparative development of the cerebrum in the lower
animals — Development of the cerebrum in different races of men and in
different individuals — Ethnological table, derived from autopsies of white
and negro brains — Table of weights of the encephalon in different indi-
viduals— Location of the faculty of articulate language hi a restricted por-
tion of the anterior cerebral lobes, Page 313
CHAPTER XIII.
THE CEREBELLUM.
Some points in the physiological anatomy of the cerebellum — Course of the
fibres in the cerebellum — General properties of the cerebellum — Functions
of the cerebellum — Extirpation of the cerebellum in animals — Incomplete
extirpation of the cerebellum — Pathological facts bearing upon the func-
tions of the cerebellum — Andral's cases — Other cases of disease of the
cerebellum — Connection of the cerebellum with the generative function —
Development of the cerebellum in the lower animals — Paralysis from disease
or injury of the cerebellum, 359
CHAPTER XIY.
GANGLIA AT THE BASE OF THE EXCEPHALOX.
Corpora striata — Optic thalami — Tubercula quadrigemina, or optic lobes— Gan-
glion of the tuber annulare — Medulla oblongata — Physiological anatomy of
the medulla oblongata — Functions of the medulla oblongata — Connection
of the medulla oblongata with respiration — Vital point — Connection of the
medulla oblongata with various reflex acts — Rolling and turning movements
following injury of certain parts of the encephalon — General properties of
the peduncles, 393
CHAPTER XV.
SYMPATHETIC XEBYOrS SYSTEM:.
General arrangement of the sympathetic system — Peculiarities in the intimate
structure of the sympathetic ganglia and nerves — General properties of the
sympathetic ganglia and nerves — Functions of the sympathetic system —
Yaso-motor nerves — Reflex phenomena operating through the sympathetic
system — Trophic centres and nerves, so called, .... 416
12 CONTENTS.
CHAPTER XVI.
SLEEP.
General considerations — Condition of the organism during sleep — Dreams — Re-
flex mental phenomena during sleep — Condition of the brain and nervous
system during sleep — Theories of sleep — Anaesthesia and sleep produced
by pressure upon the carotid arteries — Differences between natural sleep,
and st'jpor and coma — Regeneration of the brain-substance during sleep —
Theory that sleep is due to a want of oxygen — Condition of the various
functions of the organism during sleep, Page 446
PHYSIOLOGY OF MAN.
CHAPTER I.
PHYSIOLOGICAL DIVISIONS AND STRUCTURE OF THE NERVOUS
SYSTEM.
General considerations — Divisions of the nervous system — Physiological anatomy
of the nervous tissue — Anatomical divisions of the nervous tissue — Medul-
lated nerve-fibres — Simple, or non-medullated nerve-fibres — Gelatinous
nerve-fibres (fibres of Remak) — Accessory anatomical elements of the
nerves — Branching and course of the nerves — Termination of the nerves
in the muscular tissue — Termination of the nerves in glands — Terminations
of the sensory nerves-r- Corpuscles of Pacini, or of Yater — Tactile corpus-
cles— Terminal bulbs — Structure of the nerve-centres — Nerve-cells — Con-
nection of the cells with the fibres and with each other — Accessory anatom-
ical elements of the nerve-centres — Composition of the nervous substance —
Regeneration of the nervous tissue — Reunion of nerve-fibres.
THE nervous system is anatomically distinct in all ani-
mals, except those lowest in the scale of being. It is useless
to speculate upon the question of the existence of matter en-
dowed with properties analogous to those observed in the
nervous system of the higher animals, in beings so low in
their organization as to present no, divisions into anatomical
elements ; for the present condition of physiological science
does not admit of the recognition of functions without organs.
All animals that present any thing like nervous functions pre-
sent also an anatomically distinct nervous system. "Within
certain limits, the perfection of the animal organization de-
pends upon the general development of the nervous system.
High in the animal scale, as in the warm-blooded ani-
NEKVOTJS SYSTEM.
j the general development of this system presents little,
if any, variation ; but special attributes are coexistent with
the development of special organs. The development in
this way of particular portions of the nervous system is in
accordance with the particular conditions of existence of
different animals ; it is a necessary part of their organiza-
tion, and is not dependent upon education or intelligence.
Examples of this are in the extraordinary development of
the sense of sight, hearing, or smell, in different animals.
There are animals in which these special senses possess a
delicacy of perception to which man, even with the greatest
amount of intelligent education, can never attain ; but man,
possessing a nervous organization not superior to that of
other warm-blooded animals in its general development,
and inferior to many in the development of special organs,
stands immeasurably above all other beings, by virtue of
the immense preponderance of what is known as the en-
cephalic portion of the nervous system.
These brief general considerations will convey some idea
of the physiological importance of the nervous system ; of
the care which should be exercised in its study ; and of the
great interest attached to it, from the fact that the most
complex and important of its functions belong to human
physiology, and to human physiology alone.
"We can best define what is to be included under the
head of the nervous system, by citing certain of its prominent
and well-established properties and functions.
1. The nervous system is anatomically and physiologi-
cally distinct from all other systems and organs in the body.
It receives impressions made upon the terminal branches of
its sensory portion, it conveys stimulus to parts, determining
and regulating the operation of their functions; but its
physiological properties are inherent, and it gives to no tis-
sue or organ its special " irritability " or the power of per-
forming its particular function.1
1 We have already discussed the independence of what is called "nervous
DIVISIONS OF THE NERVOUS SYSTEM. 15
2. The nervous system connects into a coordinated or-
ganism every part of the body. It is the medium through
which all impressions are received. It animates or regulates
all movements, voluntary and involuntary. It regulates the
functions of secretion, nutrition, calorification, and all the
processes of organic life.
In addition to its functions as a medium of conduction
and communication, the nervous system, in certain -of its
parts, is capable of receiving impressions and of generating
a stimulating influence, or force, peculiar to itself. As there
can be no physiological connection or coordination of differ-
ent parts of the organism, having an active function, without
nerves, there can be no unconscious reception of impressions
giving rise to involuntary movements, no appreciation of
impressions, general, as in ordinary sensation, or special, as
in sight, smell, taste, or hearing, no instinct, volition,
thought, or even knowledge of existence, without nerve-
centres. *
Possessing, as it does, these varied properties and func-
tions, it is evidently of the greatest physiological importance
that the anatomical characters of the nervous system should
be most carefully studied, with a view, if possible, of con-
necting certain of the nervous properties with peculiarities
in structure. It is also important to subdivide the system,
as regards general properties and functions, as well as with
reference to the special office of particular parts. With this
end in view, we will point out, first, the great anatomico-
physiological divisions common to nervous matter wherever
it exists, and afterward, the subdivisions of the system as re-
gards special functions.
Divisions of the Nervous System.
Nervous matter, whatever may be its special function,
presents two great divisions, each with distinct anatomical
irritability," in treating of the properties of the muscles. See vol. iii., Move-
ments, p. 463.
102
16 NERVOUS SYSTEM.
as well as physiological differences.' One of these divisions
presents the form of fibres, or tubes. This kind of nervous
matter is incapable of generating a force or stimulus, and
serves onl j as a conductor. The other division is in the
form of cells, and this kind of nervous matter alone is capa-
ble of generating the so-called nervous force.
The nervous matter is divided into two great systems, as
follows :
1. The cerebro-spinal system, composed of the brain and
spinal cord with the nerves directly connected with these cen-
tres. This system is specially connected with the functions
of relation, or of animal life. The centres preside over gen-
eral sensation, the special senses, voluntary and some invol-
untary movements, intellection, and, in short, all of the func-
tions that characterize the animal. The nerves serve as the
conductors of impressions known as general or special sen-
sations, and of the stimulus that gives rise to voluntary and
certain involuntary movements, the latter being the auto-
matic movements connected with animal life.
2. The sympathetic, or organic system. This system is
specially connected with the functions relating to nutrition,
operations which have their analogue in the vegetable king-
dom, and are sometimes called the functions of vegetative
life. Although this system presides over functions entirely
distinct from those characteristic of and peculiar to animals,
the centres of this system all have an anatomical and phys-
iological connection with the cerebro-spinal nerves.
The cerebro-spinal system is subdivided into centres pre-
siding over movements and ordinary sensation, and centres
capable of receiving impressions connected with the special
senses, such as sight, audition, olfaction, and gustation. The
nerves which receive these special impressions and convey
them to the appropriate centres are more or less insensible
to ordinary impressions. The organs to which these special
nerves are distributed are generally of a complex and pecul-
iar structure, and present numerous accessory parts which
ANATOMY OF THE NERVOUS TISSUE. 17
are important and essential in the transmission of the special
impressions to the terminal branches of the nerves.
In treating of the nervous system, we will consider first
the physiological anatomy of the nervous tissue ; next, the
general properties of the cerebro-spinal system ; next, the
functions of different portions of this system connected with
motion, ordinary sensibility, intellection, etc. ; next, the func-
tions of the sympathetic, or organic system of nerves ; and
finally, the special senses, with the physiological anatomy
and mechanism of the accessory parts.1
Physiological Anatomy of the Nervous Tissue.
The physiological anatomy of the nervous system natu-
ally divides itself into two sections ; one embracing what is
called the general anatomy of the nervous tissue, and the
other, the arrangement of this tissue in special organs, as
far as this is connected with their functions.
The intimate structure of the different portions of the
nervous system may now be regarded as tolerably well un-
derstood, at least as far as those anatomical points bearing
on physiology are concerned. The connection between the
nerve-cells and the fibres and the modes of termination of the
motor filaments in the muscles are points nearly, if not quite,
settled ; and the terminations of sensory filaments in integu-
ment and mucous membranes have lately been investigated
very thoroughly, and with quite positive and satisfactory re-
sults. These anatomical points are especially connected with
the general properties of the nervous system, both as a gen-
erator of the so-called nerve-force and as a conductor.
The arrangement of the nervous elements in special or-
gans, as in the brain and spinal cord, has not been so suc-
cessfully investigated, and presents immense difficulties in
its study ; and we can hardly hope to acquire any thing like
1 The special senses will be fully considered in the fifth and last volume of
this series.
18 NEKVOUS SYSTEM.
a definite and thorough knowledge of the functions of these
parts, until we have much more positive information con-
cerning their anatomical characters.
Anatomical Divisions of the Nervous Tissue. — The phys-
iological division of the nervous system into nerves and
nerve-centres is pretty well carried out as regards the ana-
tomical structure of these parts. The two great divisions of
the system, anatomically considered, are into nerve-cells and
nerve-fibres.
The nerve-cells, as far as we know, are the only parts
capable, under any circumstances, of generating the nerve-
force ; and, as a rule, they cannot receive impressions in any
other way than through the nerve-fibres. There are, how-
ever, some exceptions, either apparent or real, to this rule,
as in the case of direct irritation of the ganglion of the tuber
annulare, 'and the sympathetic ganglia, which seem sensible
to direct irritation ; but the cells of most of the ganglia be-
longing to the great cerebro-spinal axis are insensible to
direct stimulation and will only receive impressions con-
ducted to them by the nerves.
The nerve-fibres act only as conductors, and are incapa-
ble of generating nerve-force. There is no exception to this
rule, but there are differences in the properties of certain
fibres. The nerves generally, for example, will receive di-
rect impressions, the motor filaments conducting these to
the muscles and the sensory filaments conveying the im-
pressions to the centres. These fibres will also conduct the
force generated by the nerve-centres. But there are many
fibres, such as those composing the white matter of the
encephalon and the spinal cord, that are insensible to direct
irritation, while they will convey to the centres impressions
made by the sensitive nerves, and will conduct to the motor
nerves stimulus generated by nerve-cells.
Structure of the Nerves. — There are few anatomical ele-
MEDULLATED XERVE-FIBRES. 19
ments that present greater variations in size and appearance
than the nerve-fibres. Certain fibres found in the course of
the nerves between the muscles are as large as y^Vrr °f an
inch, have dark borders, and possess three well-marked
structures ; viz., a tubular membrane, medullary contents,
and an axial band ; others, with the same structure, are only
saooo of an inch in diameter ; others have only the medul-
lary covering and the axial band ; and others present the
axial band alone. Most of these anatomical elements have
essentially the same physiological conducting properties;
the variations in their structure depending upon differences
in their anatomical relations. In view of these facts, it will
be convenient to adopt some anatomical classification of the
fibres.
In the most simple classification of the nerve-fibres, they
are divided into two groups; one embracing those fibres
which have the conducting element alone, and the other
presenting this element surrounded by certain accessory
structures. In the course of the nerves, the simple fibres are
the exception, and the other variety is the rule ; but as the
nerves are followed to their terminations in muscles or sensi-
tive parts, or are traced to their origin in the nerve-centres,
we find that they lose one or another of their adventitious
elements. These two varieties we shall term : 1. The me-
dullated fibres, and 2. The simple, or non-medullated fibres.
nUated Nerve-fbres. — These fibres are so called by
French and German writers because, in addition to the axis-
cylinder, or conducting element, they contain, enclosed in a
tubular sheath, a soft substance called the medulla. This
substance is strongly refractive and gives the nerves a pecu-
liar appearance under the microscope, from which they are
sometimes called the dark-bordered nerve-fibres. . As the
whole substance of the fibre is enclosed in a tubular mem-
brane, these are frequently spoken of as nerve-tubes.
If the nerves be examined while perfectly fresh and un-
20 NERVOUS SYSTEM.
changed, their anatomical elements appear in the form of
simple fibres with strongly accentuated borders. The diam-
eter of these fibres is from ^fa to -p^Vo" of an inch.1 To
observe the fibres in this way, it is necessary to take a nerve
from an animal just killed and examine it without delay.
In. a very short time the borders become darker and the
fibre assumes an entirely different appearance. By the use
of certain reagents, it can be demonstrated that a medullated
nerve-fibre is composed of three distinct portions ; viz., a
homogeneous sheath, a semi-fluid matter contained in the
sheath, and a delicate central band.
The tubular sheath of the nerve-fibres is a somewhat elas-
tic, homogeneous membrane, never striated or fibrillated,
and presenting generally oval nuclei, with their long diam-
eter in the direction of the tube. This is sometimes called
the neurilemma, a name, however, which is more generally
applied to another membrane. It is sometimes spoken of,
also, as the " limiting membrane of Valentin," or " the sheath
of Schwann." In its chemical and general properties, this
membrane resembles the sarcolemma, though it is less elas-
tic and resisting. It exists in all the medullated nerve-fibres,
large and small, except those in the white portions of the
encephalon and spinal cord. It is not certain that it does not
exist in the small, non-medullated fibres, though its presence
here has never been satisfactorily demonstrated.2 As we
before remarked, the tubular membrane cannot be seen in
the perfectly fresh nerves ; and even after they have become
changed by desiccation, its demonstration requires the use of
reagents. In the ordinary medullated fibres, however, it
may be isolated by boiling the nerve in absolute alcohol and
then in acetic acid, or by treating it with cold caustic soda.
By then boiling the nerve for an instant in the caustic soda,
fragments of the tube may be isolated, when they resemble
the membrane forming the canals of the kidney. Another
1 LITTRE ET ROBIN, Didionnaire de mededne, Paris, 1865, Article, Nerveux.
9 KOLLIKER, Element cPhistologie humaine, Paris, 1868, p. 315.
MEDULLATED NERVE-FIBRES. 21
method is to treat the nerve with fuming nitric acid, after-
ward adding a solution of caustic potash. The fatty sub-
stance is thus discharged in small drops, the central band is
dissolved, and the empty sheath is seen, swollen and tinged
with yellow. These are the processes employed by Kolliker,
who demonstrates in this way the presence of nuclei.1
The medullary substance fills the tube and surrounds the
central band. This is called by various names ; as myeline,
white substance of Schwann, medullary sheath, nervous me-
dulla, etc. It does not exist either at the origin of the nerves
in the gray substance of the nerve-centres or at the periphe-
ral termination of the nerves, and is probably not an essential
conducting element. When the nerves are perfectly fresh,
this substance is transparent, homogeneous, and strongly
refracting, like oil ; but as the nerves become altered by des-
iccation, the action of water, acetic acid, and various other
reagents, it coagulates into an opaque, granular mass. The
consistence of this substance gives to the medullated fibres a
very peculiar appearance. The tubular membrane being
very thin and not elastic, the white substance, by very slight
pressure, is made to fill the tubes irregularly, giving them a
varicose appearance, which is entirely characteristic. In ex-
amining a preparation of the nervous tissue, large drops,
coagulated in irregular shapes, are seen scattered over the
field, and frequently fringing the divided ends of the tubes,
In the white substance of the encephalon and spinal cord,
where the tubular membrane is wanting, the varicose appear-
ance of the fibres is more remarkable than in any other situ-
ation.
The axis-cylinder is, in all probability, the essential ana-
tomical element of the nerves. It exists in all the nerves
except in those termed gelatinous fibres, or fibres of Eemak,
which will be described hereafter. In the ordinary medul-
lated fibres, the axis-cylinder cannot be seen in the natural
condition of the tissue, because it refracts in the same man-
1 KOLLIKER, op. tit., p. 318.
22 NERVOUS SYSTEM.
ner as the medullary substance, and it cannot "be demon-
strated afterward, on account of the opacity of the coagulated
matter. If a fresh nerve, however, be treated with strong
acetic acid, the divided ends of the fibres will retract, leaving
the axis-cylinder, which is but slightly affected by reagents.
It then presents itself in the form of a pale, slightly-flattened
band, with outlines tolerably regular, though slightly vari-
cose at intervals, somewhat granular, and sometimes very
finely striated in a longitudinal direction. This band is
elastic, but not very resisting. Its granules are excessively
pale. "What serves to distinguish it from all other portions
of the nerve-fibre is its insolubility in most of the reagents
employed in anatomical investigation. It is slightly swollen
by acetic acid, but is dissolved after prolonged boiling. If
a solution of carmine be added to the nervous tissue, the
axis-cylinder only is colored. It has been remarked that
the nerve-fibres treated with nitrate of silver present in the
axis- cylinder well-marked transverse striations. This was
observed by Frommann,1 and has since been confirmed by
Grandry.3 The latter observer is disposed to regard both
the nerve-cells and the axes of the fibres as composed of two
substances, the limits of which are marked by the regular
striae developed by the nitrate of silver. This, however, is
a point of purely anatomical interest. The presence of regu-
lar and well-marked striae in the axis-cylinder after the addi-
tion of a solution of nitrate of silver and the action of light
cannot be doubted ; but it has not yet been determined be-
yond question whether these markings be entirely artificial,
or whether the axis-cylinder be really composed of two kinds
of substance.
A still more important question with regard to the inti-
1 FROMMANN, Ueber die Fiirbung-der Binde- und Nervensubstanz des Rucken-
markes durch Argentum nitricum und uber die Struktur der Nervenzellen. —
Archiv fur pathologische Anatomic und Physiologic, etc.', Berlin, 1864, Bd. xxxi.,
S. 129, et seq. — Zur Silberfdrbung der Axencylinder, ibid., S. 151, et seq
2 GRANDRY, JDe la structure intime du cylindre de Vaxe et des cellules nerveuses.
— Journal de F anatomic, Paris, 1889, tome vi., p. 289, et seq.
NON-MEDTJLLATED NEBVE-FIBRES. 23
mate structure of the axis-cylinder refers to the longitudinal
striations. These are observed in many fibres, but they are
not constant. Some authors have adopted the view that
the markings are produced by fibrillse, analogous to the
fibrillse of the muscular fibres, in all the fibres, as well as in
those of the retina, 'Olfactory, and some of the sympathetic
nerves.1 In the organs of special sense, there can be no
doubt of the existence of fibrillse ; but this is by no means so
clearly demonstrable in the general system of nerves. Still,
it is necessary to take into consideration, in this connection,
certain facts with regard to the origin of the nerve-fibres in
the cells and their ultimate distribution in sensitive parts.
In the final distribution of sensitive nerves, we shall see that
the fibres break up into filaments resembling fibrillee, and
although the fibrillated . character of the poles of the nerve-
cells is not unreservedly accepted by anatomists, many ob-
servers positively state that such is their structure. In the
present condition of the science, we cannot do more than
state that, while a fibrillated structure has perhaps been
shown in the nerves of some of the lower orders of animals,
its existence in man and the mammalia is somewhat doubtful.
The diameter of the axis-cylinder is about one-half or one-
third that of the tube in which it is contained. The various
appearances which the nerve-fibres present under different
conditions are represented in Fig. 1.
Simple, or Non-meduUated Nerve-Flares. — These fibres
are found very largely distributed in the nervous system.
In the last edition of what is perhaps the most authoritative
work on histology, it is stated that " the more we advance
in our researches, fhe more evident it becomes that, in man
and the higher classes of animals, nerve-fibres without the
white substance are very widely distributed." a However,
1 SCHULTZE, in STRICKER, Manual of Human and Comparative Histology,
London, 1870, vol. i., p. 147, et seq.
2 KOLLIKER, op. cit., p. 322.
21 NERVOUS SYSTEM.
when we come to study the structure and relations of these
small fibres, which seem in many instances to be simple
prolongations, without alteration, of the axis-cylinder of the
medullated fibres, it will be seen that they are chiefly found
in the peripheral terminations of the nerves and in the fila-
FlG.l.
Nerve-fibres from the human subject, magnified 350 diameters ; four small fibres, of which two
are varicose, one medium-sized fibre with borders of single contour, and four large fibres; of
the latter, two have a double contour, and two contain granular matter. (KOLLIKEK, Hand-
luch der Gewebelehre, Leipzig, 1867, S. 289.)
ments of connection of the fibres with the cells. The study
of the fibres in these relations constitutes the most important
part, physiologically, of the anatomy of the nerves, and pre-
sents the greatest difficulties in the way of direct observa-
tion ; and, for that reason, we shall treat of these questions
separately, and defer until then the full consideration of the
non-medullated fibres.
Gelatinous Nerve-Fibres (Fibres of It emetic). — These
fibres are entirely different in their anatomy from either of
the varieties of fibres just considered. They are found chiefly
in the sympathetic system, and in that particular portion of
GELATINOUS NEKVE-FIBRES. 25
this system connected with involuntary movements. For
instance, these fibres are very abundant in the gray filaments
sent to parts provided with non-striated muscular fibres and
endowed with undoubted motor properties ; but they are not
found in the white filaments of the sympathetic, which seem
to be incapable of exciting movements.1
There is considerable difference of opinion among physi-
ologists with regard to the gelatinous filaments. Some are
disposed to regard them as elements of connective tissue, not
endowed with properties characteristic of nerves, while others
consider that they are nerve-fibres, probably possessing func-
tions distinct from those of the fibres of different structure.
The first opinion was formerly held by Kolliker, who states,
in one of the early editions of his work on Microscopic
Anatomy, that all of the fibres of Remak are " only a form
of connective tissue ; " 3 but in a later edition, he admits that
the nucleated fibres of the great sympathetic, which resemble
embryonic nervous elements, are really nerve-fibres.8 This
is the view now adopted by the best anatomists. While it
is certain that elements of connective tissue exist in the
nerves, and have been mistaken for true nerve-fibres, there
are in the nerves, particularly in those belonging to the
great sympathetic system, fibres exactly resembling the
nerve-fibres of the embryon. These are the true gelatinous
nerve-fibres, or fibres of Remak. It is stated that the nerves
generally have this structure up to the fifth month of intra-
uterine life, and that in the regeneration of nerves after
division or injury, the new elements assume this form before
they arrive at their full development.4
The true gelatinous nerve-fibres present the following
characters: They are flattened, with regular and sharp
borders, grayish and pale, presenting numerous very fine
1 REMAK, Observation&s de Sysfematis S"erv. Struct., Berolini, 1838, p. 5.
2 KOLLIKER, Microscopic Anatomy, London, 1860, p. 254.
8 KOLLIKER, Cements d"histologie humaine, Paris, 1868, p. 432.
4 LITTRE ET ROBIN, Dictionnaire de medecine, Paris, 1865, Article, Nerveux.
26
NERVOUS SYSTEM.
FIG. 2.
granulations, and a number of oval, longitudinal nuclei, a
characteristic which has given them the name of nucleated
nerve-fibres. The diameter of the fibres is about -g^or °f
an inch. The nuclei have nearly the same diameter as the
fibres, and are about y^Vtr of an inch in length ; l they are
finely granular, and present no nucleoli. The fibres are
rendered pale by the action of acetic acid, but they are
slightly swollen only, and present, in this
regard, a marked contrast with the ele-
ments of a connective tissue. The micro-
scopical appearances of these fibres, which
are strongly characteristic, are represented
in Fig. 2.
Accessory Anatomical Elements of the
Nerves. — The nerves present, in addition
to the different varieties of true nerve-
fibres just described, certain accessory ana-
tomical elements common to nearly all of
the tissues of the organism, such as con-
nective tissue, blood-vessels, and perhaps
lymphatics, though these have never been
demonstrated, except in the nerve-centres.
Like the muscular tissue, the nerves are
made up of their true anatomical elements,
the nerve-fibres, held together into primi-
tive, secondary, and tertiary bundles, and
nified 800 diameters. . . . . •• . r. .^
with the gelatinous so on, in proportion to the size ot the nerve.
of S ordinary°dari^ The primitive fasciculi are surrounded by
bordered nerve-fibres. IT i i •» ' i -i T> i •
(LITTRE ET KQBIN, a delicate membrane, described by Hob in
l)ictionnaire de me- -, .-, /,/.* 01^ -i • i
1865, p. under the name ot pertnevre, but which
had been already noted by other anato-
mists under different names.3 This membrane is homoe-
mag-
1 LITTRE ET ROBIN, loc. tit.
2 LITTRE ET ROBIN, Dictionnaire de mededne, Paris, 1865, Article, Fcrinevre.
8 KOLLIKER, Elements (Thistelcgie humainc, Paris, 18G8, p. 317.
ACCESSORY ANATOMICAL ELEMENTS. 27
neons or very finely granular, sometimes marked with longi-
tudinal striae, and possessing elongated nuclei, finely granular,
from ^Vo- to TOTRT °f an inch in length by from ^Vir to
TTOTF °f an mc^ wide. The thickness of the membrane is
from I2ooo to -g^nj-Q of an inch. It commences at the point
where the nerve-fibres emerge from the white portion of the
nervous centres, and extends to their terminal extremities,
being interrupted by the ganglia in the course of the nerves.
This membrane generally envelops a primitive fasciculus of
fibres, branching as the bundles divide and pass from one
trunk to another; but it is sometimes found surrounding
single fibres. An important anatomical fact connected with
this membrane is that it is never penetrated by blood-vessels,
the smallest capillaries of the nerves ramifying in its sub-
stance, but never passing through to the individual nerve-
fibres. Within the perinerve, are sometimes found ele-
ments of connective tissue, but never any other of the ac-
cessory anatomical elements of the nerves.1
The amount of fibrous tissue in the different nerves is very-
variable and depends upon the external conditions to which
they are subjected. In the nerves within the bony cavities,
where they are entirely protected, the fibrous tissue is very-
scanty ; but in the nerves between muscles, we find a toler-
ably strong investing membrane, or sheath surrounding the
whole nerve and sending processes into its interior, which
envelop smaller bundles of fibres. This sheath is formed of
inelastic fibres with small elastic fibres and nucleated con-
nective-tissue fibres. These latter may be distinguished
from the gelatinous nerve-fibres by the action of acetic acid,
which swells and finally dissolves them, while the nerve-
fibres are but slightly affected.
The late researches of Sappey have shown that the struct-
ure of the fibrous sheath of the nerves possesses certain
important anatomical peculiarities. The greatest part of
this membrane is composed of bundles of white, inelastic
1 LlTTRE ET ROBIX, loc. tit.
28 NERVOUS SYSTEM.
tissue, interlacing in every direction ; but it contains also
numerous elastic fibres, adipose tissue, a net-work of arteries
and veins, and " nervi-nervorum" which are to these struct-
ures what the vasa-vasorum are to the vessels. The adipose
tissue is constant, being found even in extremely emaciated
persons.1
The vascular supply to most of the nerves is rather scan-
ty. The arteries break up into a plexus of very fine capil-
laries, arranged in oblong, longitudinal meshes surrounding
the fasciculi of fibres ; but they never penetrate the peri-
nerve and come in contact with the ultimate nervous ele-
ments. The veins are rather more voluminous, and follow
the arrangement of the arteries. It is not certain that the
nerves in their course contain lymphatics ; at least these ves-
sels have never been demonstrated in their substance.
Branching and Course of the Nerves. — The ultimate
nerve-fibres in the course of the nerves have no connection
with each other by branching or inosculation. A bundle of
fibres frequently sends branches to other nerves and receives
branches in the same way ; but this is simply the passage of
fibres from one sheath to another ; the ultimate fibres them-
selves maintaining throughout their course their integrity
and individual physiological properties. This view with
regard to the course of the fibres in the nerves is held by
nearly all anatomists. Some, however, assert that branch-
ing and inosculation of individual fibres sometimes occur in
the course of nerves ; a but this statement is not sufficiently
confirmed, in view of the very general opinion to the con-
trary. It has long been known, since the researches of Savi,
Robin, "Wagner, and others, that in the electric organs of
certain fishes, the large nerve-fibres break up into numerous
1 SAPPEY, Recherches sur la structure de T envelope fibreuse des nerfs. — Journal
de Panatomie, Paris, 1868, tome v., p. 47, et seq.
8 SCHDLTZE, in STRICKER, Handbuch der Lehre von den Geweben, Leipzig, 1 868,
S. 119.
TERMINATION OF NEKVES EST MUSCLES. 29
oranclies before they pass to their termination ; * but there
is no such arrangement in the human subject or in the high-
er animals, in the course of the nerves, or anywhere, except
at the point where the fibres change their character just be-
fore their termination. The branching and inosculation of
the ultimate nerve-fibres will be considered in connection
with the very interesting and important question of their
ultimate distribution to muscles and sensitive parts.
Mode of Termination of the Nerves in the Voluntary
Muscles. — For a long time the actual mode of termination
of the nerve-fibres in the muscles was a question of great
uncertainty ; but within the last few years, thanks to the
elaborate researches of the French and German anatomists,
the peripheral extremities of the nerves have been so accu-
rately described and figured, that the great question of the
mode of connection between the anatomical element con-
ducting the stimulus to the muscles and the contractile
elements of the muscles themselves may be considered as
definitively settled. So many views, however, have been
presented on this subject from time to time, that an histori-
cal account of the numerous researches, within even the last
few years, would possess but little physiological interest.3
Before physiologists had any definite knowledge of the
true mode of termination of the motor nerves, the only
opinion on this subject entitled to any consideration was
that of Prevost and Dumas, who believed that they had de-
1 ROBIN, Jfemoire sitr la demonstration experimentale de la production d'electri-
cite par un appareil propre aux poissons du genre des raies. — Journal de Vana-
tomie, Paris, 1865, tome ii., p. 533, et seq.
2 Prof. Trinchese, in an historical introduction to an account of his own
observations on the peripheral termination of the nerves, gives an admirable
review of recent researches on this subject. He is in error, however, in dating
the view of the termination in loops from Valentin and Emmert, in 1836, this
theory having been advanced by Prevost and Dumas, in 1823. (TRIXCHESE, Me-
moire sur la terminaison peri.pherique des nerfs moteurs. — Journal de fanatomie,
Paris, 1867, tome iv., p. 485, et seq.}
30 NERVOUS SYSTEM.
monstrated loops at the peripheral ends of the nerves resting
on the muscular fibres. These loops were fully described and
figured in 1823,1 and this view was afterward quite gener-
ally adopted by physiologists ; but it has been so completely
overthrown by recent observations, that it is not now a ques-
tion for discussion. In 1840, Doyere gave an account of the
peripheral termination of the motor-nerves,3 probably as
accurate as was possible with his imperfect means of in-
vestigation ; but, as is justly remarked by Prof. Trinchese,
this observation, though confirmed a few years later by
Quatrefages,8 seems to have been lost sight of by most phys-
iological writers.4 In view of these early researches, it is
unnecessary to consider elaborately the claims to priority of
more recent observers, the results of whose investigations
present slight and unimportant differences ; and, although
these have been brought forward and warmly discussed 6 as
a matter of controversy, they possess but little interest.
"We shall not enter into any further discussion of the
views expressed by different anatomists with regard to the
question under consideration, but will now simply describe
the connection between the peripheral nerves and the mus-
cles, as it appears from the researches that seem to be the
most exact and reliable. Without underestimating the value
of other researches, we may state that those of Rouget repre-
sent, perhaps, the present condition of the question as well as
any. As we before remarked, the differences between the
1 PREVOST ET DUMAS, Memoire sur left phenomenes qui accompagnent la con-
traction de la fibre musculaire. — Journal de physiologic, Paris, 1823, tome iii.,
p. 322.
2 DOYERE, Memoire sur les tardigrades. — Annales des sciences naturelles, Zoo-
Ugie, Paris, 1840, tome xiv., p. 346.
3 QUATREFAGES, Memoire sur Veolidine paradoxale. — Annales des sciences na-
turelles, Zoologie, Paris, 1843, tome xix., p. 300.
4 JTrinchese (loc. cit.) alludes to the observations of Doyere, which are also
fully discussed by Kuhne (STRICKER, Handbuch der Lehre von den Geweben, Leip-
zig, 1868, S. 147, et seq.).
5 BEALE, An Anatomical Controversy. The Distribution of Nerves in Volun-
tary Muscle, etc., London, 1865, pp. 38.
TERMINATION OF NERVES EST MUSCLES. 31
most reliable observations of recent writers are nearly all
unimportant; and while future investigations may enable
us to go further in following some of the elements of the
nerve-fibres, they will, in all probability, simply extend our
knowledge without invalidating the information already ac-
quired.
The observations of Eouget were published in 1862, and
were made upon lizards, frogs, Guinea-pigs, rats, and other
animals, and confirmed in the human subject.1 The tis-
sues were taken either from the living animal or from an
animal just killed, and were examined, in some instances,
without the addition of reagents ; but the most satisfactory
results were obtained by macerating the muscles for from six
to twenty-four hours in a liquid containing j^Vo" °f hydro-
chloric acid, and adding to the preparation on the glass slide
a drop of a solution of sugar in water. In preparations made
in this way, it is easy to trace the course of the nerves to
their termination. The following is the description given
by Rouget-:
" The nervous trunks and the branches of distribution
generally cross the course of the' muscular fibres. As re-
gards the terminal ramifications, sometimes they meet the
muscular fibres at nearly a right angle, and sometimes they
are placed nearly parallel to the axis of the primitive fascic-
uli. Branches of distribution are detached sometimes from
branches containing two or three fibres, and sometimes from
isolated fibres. After a very short course these tubes divide,
and may present as many as seven or eight successive divis-
ions. Most commonly, the termination takes place either
by divisions of the second or third order, or the same tube
gives off, successively, divisions which pass to the adjacent
primitive fasciculi and terminate here without new divisions
and after a very short course. They have a less diameter
1 ROUGET, Memoire sur la termination des nerfs moteurs dans les muscles chez
les reptiles, les oiseaux et les mammiferes. — Journal de la physiologic, Paris, 1862,
tome v., p. 574, et seq.
103
32 NERVOUS SYSTEM.
than the primitive nerve-tubes, but they preserve even tc
the terminal extremity their double contour, and there can
be demonstrated, very easily, a sheath provided with nuclei,
a medullary layer, and the axis-cylinder. Never do we ob-
serve at the termination of the motor nerves the pale and
non-medullated fibres described by Kuhne and Kolliker.
At the point where the tube terminates, we remark con-
stantly a special arrangement which has no analogy with
that which has been described in the batrachia by these two
observers, and which Kuhne believed could be extended to
the higher vertebrata, to the mammalia, and to the human
subject. The nerve-tube, with a double contour, preserving
still a diameter of from -g^-^ to -g^Vir °f an mcn a* ^he point
where it touches the primitive fasciculus to become arrested
at its surface, terminates by an expansion of the central
nerve-substance, the axis-cylinder, which is in immediate
contact with the contractile fibres (fibrillse) of the primitive
fasciculus. The layer of medullary substance ceases ab-
ruptly at this point, the sheath of the tube is spread out and
blended with the sarcolemma ; but in immediate continuity
with the axis-cylinder, a layer, a plate of granular substance,
from -g-jnnr to ^-g-j-o °^ an mcn m thickness, is spread out be-
neath the sarcolemma, on the surface of the fibrillse, in a space
generally oval and about y^Vo °f an mcn wide in its short
diameter, and -g-J-^- of 3n inch in its long diameter. This
granular substance masks more or less completely, in the
space which corresponds to it, the transverse strige of the
muscular fasciculus. The disk itself has exactly the granu-
lar appearance of the substance of the axis-cylinder in the
vertebrata, and of that of the nerve-tubes in most of the inver-
tebrata, especially after being treated by diluted acids. But
that which essentially characterizes the terminal plates of the
motor nerves is an agglomeration of nuclei observed at
their site. "With a low magnifying power, even, we can dis-
tinguish the point where a nerve-tube touches the primi-
tive fasciculus to which it belongs, and ends abruptly at its
TEEMDxATION OF NERVES IX MUSCLES. 33
surface, by a collection of from six to twelve or even sixteen
nuclei which occupy the site of the terminal plate. These nu-
clei are distinguished by their size as well as by their form,
which is less elongated than the nuclei of the muscular
tissue (connective-tissue nuclei of the primitive fasciculi).
They present, however, the most complete analogy with the
nuclei of the nerve-sheath (connective-tissue nuclei of the
newes). They are, without any doubt, nothing else than
the nuclei which, scattered throughout the entire length of
the sheath, are collected in a mass at the point where the
covering of the nerve-fibre is spread out and fuses with the
sarcolemma of the primitive fasciculus."
There can be little if any doubt that the description just
given represents the mode of termination of the nerves in
the voluntary muscles in man and the mammalia. The ob-
servations of Kolliker,1 who describes a plexus of pale fibres
with nuclei instead of a well-defined terminal plate, were
made upon frogs, and are probably correct ; and Kolliker ad-
mits the accuracy of the observations of Rouget as regards
reptiles, birds, and the mammalia.11 The views of Beale 3 are
only entitled to consideration in so far as they confirm previ-
ous observations. His descriptions and figures, as far as we
know, are not accepted, nor have they been confirmed by
any anatomist who has investigated the subject. The ap-
pearances of the terminal plates are represented in Fig. 3.
Although the sensibility of the muscles is slight as com-
pared with that of the tegumentary tissues, they undoubtedly
possess nerve-fibres other than those exclusively devoted to
motion. In addition to the fibres just described, Kolliker
and some others have noted fibres with a different mode of
termination. These Kolliker believes to be sensitive nerves,
and their mode of termination has not been so definitely de-
scribed as in the fibres with terminal motor plates. ^We
refrain from giving a very full description even of what has
1 KOLLIKER, Clements d^histologie humaine, Paris, 1868, p. 222, et seg.
2 KOLLIKER, op. «7., p. 225. 3 Loc, cit.
M NERVOUS SYSTEM.
been observed with regard to the termination of these fibres,
for future and more successful researches will probably mod-
ify the views now held with regard to this point. Kolliker '
states that the fibres in question are very fine, dark-bordered
tubes, with a medulla ted sheath, which, when studied in
Mode of termination of the motor nerves, after Booget
of tiHj thrro^Ttwl muscle o* the ham«» rabjectMidit?
ahv ftadnta: ft.»tri»4*l»; & medullary substam* of the tube, which
to the terminal plate, where it disappears; 4
of the feud, in which a nerve-tube tenm-
of the sheath: 8, 3, samfemma becoming
. : ::.r Mrr«-«nhc
nates.— 1.1. sheath of the nerve-tube :i
continue* with the sheath
the site of the terminal pbte: 5.5.
sahstance which farms the principal
r;**1^1^
muscular tissue rendered pale by acetic acid, may be seen to
give off exceedingly fine, non-medullated fibres, which ter-
minate in fibres of the same appearance, but provided
nuclei. It does not .appear to be certain how these fibres
end. Kolliker is not satisfied that the free extremit:
they appear to be, are the actual terminations ; but he as-
serts that in some rare instances they communicate with
each other. For the present this point must be considered
as unsettled.
Mode of Termination of the Werres in the . +ary
Muscular Tissue. — The nerves have not been followed out
1 KOUJKEK, op. at., p. 228.
TERMINATION OF NERVES IN GLANDS. 35
BO satisfactorily in the involuntary as in the striated muscu-
lar system ; and as most, if not all of the fibres are derived
from the sympathetic system, which contains numerous
fibres of Remak the terminations of which have not been
described, it is evident that our information concerning this
part of the peripheral nervous system must be incomplete.
Perhaps the most remarkable of the late observations upon
this point are those of Dr. Frankenhaeuser, upon the nerves
of the uterus. These researches were very elaborate ; but
the point most interesting in this connection is that the
nerves, having formed a plexus in the connective tissue, send
exceedingly small fibres into the sheets or layers of muscu-
lar-fibre cells, which branch and finally go into the nucleoli
of these structures.1 Arnold has confirmed these observa-
tions, and has shown farther that in many instances the fine
terminal nerve-fibres branch and go into the nuclei of the
muscular fibres, and then pass out to join with other fibres
and form a plexus.8
Termination of the Newes in Glands. — The great in-
fluence which the nervous system exerts upon secretion at-
taches considerable interest to recent researches into the
ultimate distribution of the nerves in the glands. It must
be remembered, however, in these, as in all observations
upon the destination of the smallest nerve-fibres, that the
problem is one of the most difficult in the whole range of
minute anatomy ; and the results arrived at must be received
1 FRAXKENHAEUSER, Die Nerven der Gebaermutter und ihre Endigung in den
glatten ITuskel-fasern, Jena, 1867, S. 76, Taf. viii.
8 ARNOLD, in STRICKER, Manual of Human, and Comparative Histology, Lon-
don, 1870, vol. i., p. 195, et seg. The exact mode of termination of the nerves
in the organic muscles cannot be regarded as definitively settled. We have at-
tempted, however, to give what seem to be the most reliable views on this sub-
ject, deduced from recent observations. For a further discussion of some of
the points which we have accepted as probable, the reader is referred to a recent
article by Krause. (Die Nervenendigung in den glatten Muskelen. — Archiv fur
Anatomic, Physiologic und wissenschaftliche Medicin, Leipzig, 1870, S. 1, et seg.)
36 NERVOUS SYSTEM.
with a certain amount of caution, until they shall have been
amply confirmed.
The researches of Pfliiger upon the salivary glands leave
no doubt as to the fact that medullated nerve-fibres pass to
the cells of these organs and there abruptly terminate, at
least as dark-bordered fibres. This author believes, how-
ever, that, having formed a more or less branching plexus,
non-medullated fibres pass directly into the glandular cells,
and he gives figures which seem to illustrate this arrange-
ment pretty clearly. The same observer describes and fig-
ures multipolar cells, mixed with the glandular cells, in
which some of the nerve-fibres terminate.1
Modes of Termination of the Sensory Nerves. — There
are undoubtedly several modes of termination of the sensi-
tive nerves in integument and mucous membranes, some of
which have been accurately enough described, while others
are still somewhat uncertain. In the first place, anatomists
now recognize three varieties of corpuscular terminations,
differing in their structure, probably, according to the differ-
ent functions connected with sensation, with which the parts
are endowed. In addition, it is probable that many sensi-
tive nerves are connected with the hair-follicles, which are
BO largely distributed throughout the cutaneous surface.
There are, also, terminal filaments not connected with any
special organs, some of them, perhaps, ending simply in free
extremities, and some connected with epithelium. There is
still considerable difference of opinion among anatomists
1 PFLUGER, in STRICKER, Manual of Human and Comparative Histology, Lon-
don, 1870, vol. i., p. 433, et seq. The views here advanced by Pfliiger have been
confirmed by him in more recent observations and extended to the pancreas
(Journal of Anatomy and Physiology, Cambridge and London, 1870, vol. iv., p.
156). Pfliiger states, also, his belief that the same connection exists between the
nerves and the liver-cells (ibid., p. 188). The question, however, is still some-
what uncertain, and Mayer, in examinations of the salivary glands, found fila-
ments in connection with the nuclei, but failed to satisfy himself that they were
nervous (Quarterly Journal of Microscopical Science, London, April, 1870, p. 199)
CORPUSCLES OF PACINI, OR OF VATEK. 37
concerning all of these various points, but with regard to the
terminal corpuscles, these differences are purely anatomical,
and do not materially affect the physiology of sensation.
"We do not propose, therefore, to enter fully into the discus-
sions upon these questions, and will simply present what
seem to be the most reasonable views of the latest and most
reliable observers.
Corpuscles of Pacing or of Vater. — These corpuscles,
which were the first discovered and described in connection
with the sensitive nerves, were called corpuscles of Pacini,
until it was shown that they had been seen about a century
and a half ago by Yater. Their actual mode of connection
with the nerves, however, has only been ascertained within
the last few years. The following are the measurements of
these bodies and the situations in which they are found,
taken from Kolliker : 1
In man, these corpuscles are oval or egg-shaped, and
measure from ^j- to % of an inch in length. They are always
found in the subcutaneous layer on the palms of the hands
and the soles of the feet, and are most numerous on the
palmar surfaces of the fingers and toes, particularly the third
phalanges. In the entire hand there are about six hundred,
and about the same on the feet. They are sometimes, but
not constantly, found in the following situations : The dor-
sal surfaces of the hands and feet ; on the cutaneous nerves
of the arm, the forearm and the neck, the internal pudic
nerve, the intercostal nerves, all of the articular nerves of
the extremities, the nerves beneath the mammary glands,
the nerves of the nipples, and in the substance of the
muscles of the hands and feet. They are found without ex-
ception on all of the great plexuses of the sympathetic sys-
tem, in front of and by the sides of the abdominal aorta, and
behind the peritoneum, particularly in the vicinity of the
1 KOLLIKER, Elements d'histologie humaine, Paris, 1868, p. 141.
38
NERVOUS SYSTEM.
pancreas. They sometimes exist in the mesentery, and have
been observed near the coccygeal gland.
The structure of the cor-
puscles consists simply of sev-
eral layers of connective tis-
sue enclosing a central bulb
in which is found the terminal
extremity of .the nerve. This
bulb is finely granular, nucle-
ated, and is considered by most
anatomists to be composed of
connective tissue. At the base
of the corpuscle is a pedicle
formed of connective tissue sur-
rounding a medullated nerve-
fibre which penetrates the cor-
puscle and terminates in the
central bulb.
The only really important
point of discussion with refer-
ence to the structure of the
nerve-fibre in the central bulb,
and this is purely anatomical,
is whether or not the medul-
lary substance extends into the
corpuscle itself. Probably the
fibre is here reduced simply
to the axis-cylinder. Kolliker
thinks that there is a very thin
layer of medullary substance,
but he states that this is a ques-
and extremities of the fibre. ' (KOLLIKER, +• ,. J'ffi T, j -i • i i A n
Handbuch der Gewelelehre Leinzi°- 1S6T tlon CUmCUit tO deClCle. All
8.108.) . . , . 1
anatomists agree that a single
thin, flat fibre penetrates the corpuscle and terminates near
its summit in two or three branches, with slightly enlarged
1 Op. tit., p. 143.
TACTILE CORPUSCLES. 39
and granular extremities. The arrangement of the different
anatomical elements is shown in Fig. 4.
The situation of these corpuscles beneath, instead of in
the substance of the true skin, shows that they cannot be
properly considered as tactile corpuscles, a name which is ap-
plied to other structures situated in the papillae of the coriiim ;
and it is impossible to assign to them any special function
connected with sensation, such as the sense of temperature,
or the appreciation of pressure or weight. All that we can
say with regard to them is that they constitute one of the
several modes of termination of the nerves of general sensi-
bility.
Tactile Corpuscles. — The name tactile corpuscles implies
that these bodies are connected with the sense of touch ; and
this view is sustained by the fact that they are found almost
exclusively in parts endowed to a marked degree with tac-
tile sensibility. They are sometimes called the corpuscles of
Meissner and Wagner, after the anatomists by whom they
were first described. The most interesting researches into
their structure, however, are of later date. The view ordi-
narily accepted with regard to the structure of these bodies
is that adopted by Kolliker, who has himself investigated
their anatomy very closely ; but his researches have been
controverted very strongly by Eouget. All are agreed con-
cerning the situations where these corpuscles are found, their
number, etc., the discussions with regard to their structure
being confined to their mode of connection with the nerve-
fibres.
The true tactile corpuscles are found in greatest number
on the palmar surfaces of the hands and fingers and the plan-
tar surfaces of the feet and toes. They exist, also, in the
skin on the backs of the hands and feet, the nipples, and a
few on the anterior surface of the forearm. As we shall see
when we come to describe them fully, they are situated in
the substance of the papillae of the skin, and they cannot fail
4:0 NERVOUS SYSTEM.
to have an important function in connection with the sense
of touch.
"We have already treated of the structure of the skin in
another volume,1 where we have seen that the largest pa-
pillae, measuring from ^¥ to -g-J-g- of an inch in length, are
found on the hands, feet, and nipples, precisely where the
tactile corpuscles are most abundant. Corpuscles do not
exist in all papillae, and are found chiefly in those called com-
pound. In the space of about -^ of an inch square on the
third phalanx of the index-finger, Meissner counted four
hundred papillae, in one hundred and eight of which he found
tactile corpuscles, or about one in four. In the same space on
the second phalanx, he found forty corpuscles ; on the first
phalanx, fifteen ; eight on the skin of the hypothenar emi-
nence ; thirty-four on the plantar surface of the ungual phalanx
of the great-toe ; and seven or eight in the skin on the middle
of the sole of the foot. In the skin of the forearm, the cor-
puscles are very rare.2 Kolliker states, also, that the tactile
corpuscles usually occupy special papillae, which are not pro-
vided with blood-vessels ; so that the papillae of the hand
may be properly divided into vascular and nervous.
The form of the tactile corpuscles is oblong, with their
long diameter in the direction of the papillae. Their length
is from -g-J-g- to -^-5- of an inch. In the palm of the hand, they
are from -%^ to y-J-g- of an inch long, and from -g-g-^- to -g-j-g. of
an inch in thickness.3 They are generally situated at the
summits of the secondary eminences of the compound pa-
pillae.
It is almost certain that the tactile corpuscles consist of
connective-tissue elements, with nerve-fibres making a few
spiral turns on their surface and finally disappearing in their
substance. This view is most ably supported by Kolliker, in
opposition to the proposition advanced by Eouget, that the
1 See vol. iii., Excretion, p. 115.
2 KOLLIKER, Elements d'histologie Jiumaine, Paris, 1868, p. 139.
3 KOLLIKER, op. cit., p. 138.
TACTILE CORPUSCLES. 41
strise on the surface of the corpuscles are produced exclusively
by nerve-fibres. According to Kolliker, the tactile corpuscles
consist of a central bulb of homo-
FIG. 5.
geneous or slightly granular con- . ^
nective-tissue Substance, analo-
gous to the central bulb of the
Pacinian corpuscles, and a cov-
ering. Treated with acetic acid,
the covering presents numerous
elongated nuclei arranged in a
circular manner, which he be-
lieves to be nuclei of connective
tissue, and a few fine elastic fibres.
One, two, and sometimes three
or four dark-bordered nerve-fibres
Cutaneous papilla. — er, cortical layer with
paSS from the SubcutaneOUS ner- plasmatic cells and fine elastic fibres ;
&, tactile corpuscle, with transverse
VOUS pleXUS tO the base Of each nuclei; c, afferent nervous branch,
__.. with its nucleated neurilemma ; c?,
COrpUSCle. liiese SUrrOUnd the nerve-fibres encircling the corpuscle:
. e, the apparent termination of one of
COrpUSCle With two Or three Spiral these fibres. (KOLLIKER, Hanflbnc.il
der GewebeMire, Leipzig, 1S67, S. 106.)
turns, and terminate by pale ex-
tremities at the surface of the central bulb.1 This arrange-
ment is shown in Fip\ 5.
O
Rouget believes that the spiral lines on the surface of
the corpuscles are produced exclusively by gelatinous, nu-
cleated nerve-fibres which cover them completely, some-
times dividing and sometimes remaining single, and that
the fibres terminate in a nucleated central mass, entirely
analogous to the nucleated expansion of the motor nerves.
He claims to have demonstrated this in preparations
treated for two or three days in a liquid containing one drop
of acetic acid in about three and a third fluidounces of water,
and afterward washed in pure water, which denudes the
papillae of their epithelium.2 In his endeavor to establish a
1 KOLLIKER, op. cit., p. 138.
2 ROUGET, Memoire sur les corpuscles nerveux qui se rencontrent d Vorigine des
nerfs sensitifs, dans les papilles de la peau et des muqueuses, — Archives de physi-
ologie, Paris, 1868, tome i., p. 599.
4:2 NERVOUS SYSTEM.
complete analogy between the terminations of the sensitive
and the motor nerve-fibres, Rouget does not seem to be en-
tirely sustained ; for the behavior of the different anatomical
elements of the tactile corpuscles when treated by acetic
acid, and again when colored with carmine, shows conclu-
sively the presence of connective-tissue elements in their
outer covering. The observations of Kolliker and others
leave no doubt upon this point ; l and as we have already
seen in treating of the structure of the nerve-fibres,2 the
changes produced by acetic acid enable us to readily distin-
guish the gelatinous nucleated fibres from the elements of
connective tissue. While the exact mode of termination
of the fibres in the tactile corpuscles is not perfectly clear,
we must adopt for the present the views of Kolliker, as the
most reasonable and satisfactory.
Terminal I>ulbs. — Under this name, a variety of cor-
puscles has lately been described by Krause3 as existing in
the conjunctiva covering the eye and in the semilunar fold,
the fioor of the buccal cavity, the tongue, the glans penis,
and the clitoris. They bear some analogy to the tactile cor-
puscles, but are much smaller and more simple in their struct-
ure. They form simply a rounded or oblong enlargement
at the ends of the nerves, which is composed of homogeneous
matter with an exceedingly delicate investment of connec-
tive tissue. They measure from 10100 to -^fa of an inch in
diameter. In the parts provided with papillae, they are situ-
ated at the summits of the secondary elevations.
The arrangement of the nerve-fibres in these corpuscles
is very simple. One, two, or three medullated fibres pass
from the submucous plexus to the corpuscles. The invest-
ing sheath of the fibres is here continuous with the con-
nective-tissue covering of the corpuscle, and the nerve-
1 Loc. clt. 2 See page 26.
8 W. KRAUSE, Die terminalen Korperchen der einfach sensibilen Nerven, Han-
nover, 1860, S. 125, et sea.
TERMINAL BULBG. 43
fibres pass into the corpuscle, break up into two or three
divisions, and terminate in convoluted or knotted coils.
FIG. 6.
B
A. Three corpuscles of Krause from the conjunctiva of man, treated with acetic acid (magni-
fied 300 diameters ) ; after a drawing by Ludden. — 1, spherical corpuscle, with two nerve-
fibres which form a knot in its interior. Portions of two pale nerve-fibres are also seen. 2,
a rounded corpuscle presenting a nerve-fibre and fatty granulations in the internal bulb; 3,
an elongated corpuscle with a distinct terminal fibre. In these three corpuscles, the covering,
nucleated in 1 and 2, is distinguished.
B. Terminal bulbs from the conjunctiva of the calf, treated with acetic acid (magnified 300 di-
ameters) : after a drawing by Ludden. — 1. extremity of a nerve-fibre with its bulb : '2, double
bifurcation of a nerve-fibre, with two terminal bulbs : a. covering of the terminal bulbs : 6,
internal bulb ; c, pale nerve-fibre. (KOLUKEE, Handbuch der Gewebelehre, Leipzig, 1867,
S. 103.)
The nerve-fibres are medullated for a certain distance, but
their terminations are generally pale. The above is one
44 NERVOUS SYSTEM.
form of these corpuscles. Sometimes, however, the terminal
bulbs are oblong, and sometimes but a single nerve-fibre
penetrates the bulb and terminates in a simple pale filament.
The principal forms of the terminal bulbs are shown in Fig. 6.
General Mode of Termination of the Sensory Nerves. —
The actual termination of the sensitive nerves upon the gen-
eral surface and in mucous membranes is still a question of
great obscurity. Though we have arrived at a pretty defi-
nite knowledge of the sensitive corpuscles, it must be t re-
membered that there is an immense cutaneous and mucous
surface in which no corpuscles have as yet been demon-
strated ; and it is in these parts, endowed with what we may
call general sensibility, as distinguished from the sense of
touch, that we have to study the mode of termination of the
nerves.
Kolliker is of the opinion that, in the immense majority
of instances, the sensitive nerves terminate in some way in
the hair-follicles.1 If this be true, it will account for the
termination of the nerves in by far the greatest portion of
the skin, as there are few parts in which hair-follicles do not
exist ; but, unfortunately, the exact mode of connection of
the nerves with these follicles is not apparent. The fol-
lowing is all we know positively of the terminations of the
nerves on the general surface :
Medullated nerve-fibres form a plexus in the deeper lay-
ers of the true skin, from which fibres, some pale and nucle-
ated and others. medullated, pass to the hair-follicles, divide
into branches, penetrate into their interior, and are there lost.
A certain number of fibres pass to the non-striated muscu-
lar fibres of the skin. A certain number pass to papillae and
terminate in tactile corpuscles, and others pass to papillge
that have no tactile corpuscles.
In the mucous membranes, as far as we know, the mode
of termination is, in general terms, by a delicate plexus just
1 Op. dt., p. U4.
STRUCTURE OF THE NERVE-CEXTRES. 45
beneath the epithelium, coming from a submucous plexus
analogous to the deep cutaneous plexus. In certain mem-
branes, we have already noted the termination in bulbs (cor-
puscles of Krause). In the cornea the fibres have been fol-
lowed more minutely than in any other situation, and the
results of recent researches on this subject are very remark-
able. These results are so recent and unexpected, that we
are hardly prepared to admit them unreservedly without
fuller confirmation. At present we can only state that the
observations of Hoyer,1 Lipmann,2 and others, confirmed in
part by Kolliker,8 seem to show that branching nerve-fibres
pass to the nucleoli of the corpuscles of the cornea and to the
nucleoli of the cells of the posterior layer of epithelium.
Structure of the Neme-centres.
A peculiar pigmentary matter in the nerve-cells and the
surrounding granular substance gives to the nerve-centres
a grayish color, by which they are readily distinguished
from the white, or fibrous division of the nervous system.
Wherever this gray matter is found, the anatomical ele-
ments of the tissue are cellular, except in the nerves formed
of gray, or gelatinous fibres. Under the general division of
nerve-centres, we include, anatomically at least, the gray
matter of the cerebro-spinal centres, the ganglia of the roots
of the spinal and certain of the cranial nerves, and the nu-
merous ganglia of the sympathetic system. In these parts
are found cells, which constitute the essential anatomical
element of the tissue, granular matter resembling the con-
tents of the cells, pale fibres originating in prolongations of
the cells, elements of connective tissue, delicate membranes
1 HOYER, Ueber den Amtritt von Nervenfaser in das Epithel der Hornhaut. —
Archiv fur Anatomie, Physiologie und wissenschaftliche ATedicin, Leipzig, 1866,
S. 180, et seq.
2 LIPPMAXN, Ueber die Endigung den Nerven im eigentlichen Gewebe nnd im
kinterea Epithel der Hornhaut des Frosches. — ArchivfUr Pathologic, Anatomie und
Physiologie, Berlin, 1869, Bd. xlviii., S. 218, et seq.
3 KOLLIKER, fitments d'histologie humaine, Paris, 1868, p. 145.
46 NERVOUS SYSTEM.
enveloping some of the cells, and vessels. The most inter-
esting and important of these structures, in their physiologi-
cal relations, are the cells and the prolongations by which
they are connected with the nerves.
Nerve-cells. — Anatomists are now pretty well agreed that
the following varieties of cells exist in the nerve-centres, and
constitute their essential anatomical elements ; viz., apolar,
unipolar, bipolar, and multipolar cells. Although some have
denied the existence of apolar cells, there can be little doubt
of their presence in the centres in small numbers, and, as is
suggested by Kolliker, they may be nerve-cells in an imper-
fect state of development. The nerve-cells present great
differences in their size and general appearance, and some
distinct varieties are found in particular portions of the
nervous system, and are probably connected with special
functions.
The apolar cells are simply rounded bodies, with granular
contents, a nucleus and nucleolus like other cells, but with-
out any prolongations connecting them with the nerve-fibres.
They have been observed in the cerebro-spinal centres, and
they always exist in the sympathetic ganglia. Those who
deny their existence believe that the poles have been de-
tached in preparing specimens for examination. Unipolar
cells exist in some of the lower orders of animals, but their
presence in the human subject is doubtful. Bipolar cells
are found in the ganglia of the posterior roots of the spinal
nerves, where they are of considerable size. Smaller bipolar
cells are found in the sympathetic ganglia. Multipolar cells
present three or more prolongations.
Small cells, with three, and rarely four prolongations,
are found in the posterior cornua of the gray matter of the
spinal cord. From their situation they have been called
sensitive cells. They are undoubtedly found in greatest
number in parts known to be endowed exclusively with
sensitive properties.
NERVE-CELLS. 4:7
Large, irregularly-shaped nmltipolar cells, with numer-
ous prolongations, are found chiefly in the anterior cornua
of the gray matter of the spinal cord, and have been called
motor cells. These sometimes present as many as ten or
twelve poles. .
With all these differences in the size and form of the
nerve-cells, they present tolerably uniform general charac-
ters as regards their structure and contents. Leaving out
the apolar and unipolar cells, the perfectly-developed cells
are of an exceedingly irregular shape, with strongly-refract-
ing, granular contents, frequently a considerable number of
pigmentary granules, and a distinct nucleus and nucleolus.
The nucleus in the adult is almost invariably single, though,
in very rare instances; two have been observed. Cells with
multiple nuclei are often observed in young animals. The
nucleoli are usually single, but there may be as many as four
or five. The strongly-refracting contents, the peculiar shape,
and the poles or prolongations give the nerve-cells an ex-
ceedingly characteristic appearance, which is represented in
Fig. 7. '
The diameter of the cells is as variable as their form.
They usually measure from I21go to -g^-g- of an inch ; 1 but
there are many of larger size, and some are smaller. The
nuclei measure from 2^0() to I21go of an inch.
The nerve-cells are so delicate and prone to alteration
that their study is exceedingly difficult. Sections of the
nerve-centres must be prepared with great care, and are not
easily made and preserved. In the numerous anatomical
investigations that have been made within the last few years,
the centres have generally been hardened artificially ; and
almost every investigator has used different processes and
reagents, which may account in a measure for the differ-
ences of opinion that now exist on all points connected with
the minute anatomy of these parts.
There is at the present time considerable discussion with
1 POUCHET, Precis d'histologie humaine, Paris, 1864, p. 139.
104
4:8 NERVOUS SYSTEM.-
regard to the intimate structure of the substance of the nerve-
cells, their nuclei and nucleoli, and the points involved have
a certain amount of physiological interest. In the first place,
the transverse striae in the axis-cylinder treated with nitrate
of silver, noted by Frommann and confirmed by Grandly and
others, have been observed by Grandry in the substance of
the nerve-cells.1 While this fact, perhaps, shows that the
FIG. 7.
Nerve-cell from the ferruginous substance which forms the floor of the rhomboidal sinus in man
Magnified 850 diameters. (K6LLIKEB, Handbuch der Cfewefjelekre, Leipzig, Ib67, S. 291.)
substance contained in the cells and their prolongations is
the same as the substance of the axis-cylinder, as we stated
with regard to the axis-cylinder, it is possible that the mark-
1 See page 22.
NERVE-CELLS. 49
ings may be entirely artificial, and that they do not demon-
strate the existence of two distinct substances in the tissue.
The most interesting question with regard to the struct-
ure of the nerve-cells relates to the mode of origin of their
fibres, or poles. Until quite recently these have been re-
garded as simple prolongations of the substance of the
cells ; but lately the view has been advanced that the nerve-
cells, in the human subject, are composed of regular fibrils
continuous with the poles and starting, as it were, from
the nucleoli.1 The fibrillation of the nerve-cells and their
prolongations is figured by Schultze in an article in one
of the most authoritative of the recent works on histolo-
gy ; a but some other eminent observers have failed to note
the appearances here described,8 at least in the human sub-
ject and the mammalia. "With our , present knowledge of
the physiology of the nerve-cells, the question whether or
not their substance be fibrillated has little more than an ana-
tomical interest ; but there can be no doubt that the cells of
some of the lower orders of animals possess striations more
or less regular. These, indeed, were described soon after the
cells were discovered. While there is no anatomist who de-
nies the fact that the substance of the cells is marked by
stride in many animals, the existence of an analogous ar-
rangement in the human subject is still doubtful. Some
anatomists, with Schultze, admit the striations, but have
foiled to connect them with the nuclei and nucleoli. All
admit that they are demonstrated with great difficulty; and,
1 BEALE, Indications of the Paths taken by the Nerve-currents as they traverse
the caudate Nerve-cells of the Spinal Cord and Encephalon. — Proceedings of the
Royal Society, London, 1864, vol. xiii., p. 386, et seq.
FROMMAXX, Ueber die Farbung der Binde- und Nervensubstanz des
Ruckenmarkes durch Argentum nitricum und uber die Struktur der Nervenzellen.
— Archiv fur pathologische Anatomic und Physiologic, Berlin, 1864, Bd. xxxi., S.
134.
2 SCHULTZE, in STRICKER, Manual of Human and Comparative Histology, Lon-
don, 1870, vol. i., p. 179.
» KOLLIKZR, Elements d'histologie humaine, Paris, 1868, p. 332.
50 NERVOUS SYSTEM.
while this question is so important that it can hardly be neg-
lected in studying the physiological anatomy of the nerve-
centres, it is one concerning which it seems impossible to ex-
press a positive and definite opinion.
Connection of the Nerve-cells with the Fibres and with
each other. — Although the mode of connection of the nerve-
cells with the fibres and with each other is one of the most
important, in its physiological bearings, of all the points
connected with the minute anatomy of the nerve-centres, it
is impossible, in the present state of our anatomical knowl-
edge, to answer the questions involved in a manner entirely
satisfactory. This statement is made after a thorough study
of the investigations of the most reliable modern observers,
among whom may be mentioned Stilling, Lockhart Clarke,
Kolliker, K. "Wagner, Jacubowitsch, Yan der Kolk, Deiters,
J. Dean, and Schultze, as the most prominent, with many
others who have investigated the subject more or less success-
fully.1 A full discussion of the different opinions and the
methods of investigation that have been employed would be
out of place in this work. The difficulties in the way of
arriving at positive information upon these questions are the
following :
1. The nerve-cells and their prolongations are so delicate
and easily torn that they cannot be isolated and followed for
any considerable distance, and theoretical considerations are
constantly required to fill up the deficiencies in actual obser-
vation.
2. In the study of sections of the nerve-centres, the parts
must be hardened and afterward rendered transparent by
reagents, which must produce more or less change in the
structures ; and it seems an anatomical impossibility to make
tfrese sections so as to follow out the prolongations of the
1 Kolliker gives a very full bibliography of the anatomy of the nervous- sys-
tem, to which the reader is referred for more extended information. (Elements
d'histologie humaine, Paris, 1868, p. 441.)
CONNECTION OF NERVE-CELLS WITH FIBRES. 51
cells far enough to establish beyond doubt their exact rela-
tions.
These two considerations alone are sufficient to account
for the uncertainty so apparent even in the most successful
investigations into the anatomy of the central nervous sys-
tem ; and we shall content ourselves, in view of these facts,
with giving a summary of what seems to be the probable
relation of the cells to the fibres of origin of the nerves and
to each other.
Apolar cells, if they exist at all and be not cells from
which the poles have become separated, are simple, rounded
bodies, lying between the fibres, with which they have no
other relation than that of mere contiguity. Unipolar cells
have but one prolongation, which is continuous with a
nerve-fibre. It is not certain that these exist in the human
subject.
Bipolar cells are found in the ganglia of the posterior
roots of the spinal nerves and some of the sympathetic gan-
glia. In many of the lower animals, particularly in fishes,
the cells of the ganglia of the spinal nerves are simple, nucle-
ated enlargements in the course of the sensitive nerve-fibres,
and many anatomists have inferred that the same arrange-
ment exists in man and the mammalia ; x but the constitution
of these ganglia in the higher classes of animals seems to be
entirely different. In the first place, the roots of the spinal
nerves at the ganglia are undoubtedly reenforced by the ad-
dition of new fibres, as Kolliker has shown by actual meas-
urement, the roots being sensibly larger beyond the ganglia
while the filaments of entrance and exit have the same diam-
eter.3 Direct observation upon the ganglia in man also fails
to show the arrangement so clearly demonstrable in fishes.
The cells in the posterior roots are not continuous with the
fibres passing from the periphery to the cord, but give origin
to new fibres, generally two in number, which sometimes are*
1 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 95.
* KOLLIKER, Elements d'histologie humaine, Paris, 1868, p. 419.
52 NEBVOUS SYSTEM.
single and sometimes bifurcated, and which pass, in by far
the greatest number if not in all instances, to the periphery.
The multipolar cells, with three or more prolongations,
are found in all of the ganglia, but they predominate largely
in the gray matter of the cerebro-spinal centres. It is the
question of the exact mode of connection between these cells
and the fibres of origin of the cerebro-spinal nerves and the
union of the cells with each other by commissural prolonga-
tions, that presents the greatest difficulty and uncertainty.
One point, which has been raised within a few years, is with
regard to the character of the different poles connected with
the same cell. In ordinary preparations of the central ner-
vous system, it is impossible, even with the highest available
magnifying powers, to distinguish any one pole which, in its
general characters and connections, is different from the
others ; yet, some of the anatomists to whose researches we
have alluded describe a single pole, more distinct in its out-
lines than the others, which does not branch and is to be re-
garded as an axis-cylinder. The other poles are supposed to
be of a different character, not connected with the nerve-
fibres, and always presenting a greater or less number of
branches. These views are accepted by Schultze, who gives a
figure, after Deiters, in which the contrast between the poles
is represented as very marked ; 1 but although this opinion
is accepted by other high authorities,8 it is not easy to un-
derstand how it can be received without reserve, when it
is 'so difficult, if not impossible, to follow out the poles, ex-
cept for a very short distance.
"With our present means of investigation, there seems to
be no doubt with regard to the following facts : Tracing
the nerve-fibres toward their origin, they are seen to lose
their investing membrane as soon as they pass into the
white portion of the centres, being here composed only
1 STRICKER, Manual of Human and Comparative Histology, London, 1870,
vol. i., p. 1T7.
2 KOLLIKER, fitiments (Phistologie humaine, Paris, 1868, p. 362
ACCESSORY ELEMENTS LN" THE NERVE-CENTRES. 53
of the medullary substance surrounding the axis-cylinder.
They then penetrate the gray substance, in the form of axis-
cylinders, losing here the medullary substance. In the gray
substance, it is impossible to make out of all their relations
distinctly, and we cannot assume, as a matter of positive dem-
onstration, that all of them are connected with the poles of
the nerve-cells. Still, it has been shown, in the gray matter
of the spinal cord, that many of the fibres are actual prolon-
gations of the cells, the others probably passing upward to
be connected with cells in the encephalon.
Tracing the prolongations from the cells, we find that
one or more of the poles branch and subdivide in the gray
substance, and give origin to fibres, but that these fibres do
not branch after they pass into the white substance. Other
poles connect the nerve-cells with each other by commissural
fibres of greater or less length ; but it has never been posi-
tively demonstrated that the cells are thus connected into
separate and distinct groups, though this is possible.
The accompanying figure, taken from the excellent mono-
graph on the lumbar enlargement of the spinal cord, by Dean,
shows the mode of connection between certain of the cellular
prolongations and the fibres of the anterior roots, and the
commissural fibres by which the cells are connected with each
other.
Accessory Anatomical Elements in the Nerve-centres. —
While we must regard the cells of the gray matter and the
axis-cylinder of the nerves as probably the only anatomical
elements concerned in innervation, there are other struct-
ures in the nervous system which it is important for us to
study. These are : 1, outer coverings surrounding some of
the cells ; 2, intercellular, granular matter ; 3, peculiar cor-
puscles, called myelocytes ; 4, connective-tissue elements ;
5, blood-vessels and lymphatics.
Certain of the cells in the spinal ganglia and the ganglia
of the sympathetic system are surrounded with a nucleated
Group of cells connected with the anterior roots, as seen in a transverse section, from the an-
terior cornu of the sheep. — A, entrance of the anterior roots into the cornu; 6, &, &, &, cells
connected by long, slender processes, with the anterior roots ; c, boundary of the cornu. In
this figure almost every variety of cell-connection may be seen, with bundles of fibres cross-
ing in every direction. (DEAN, Microscopic Anatomy of the Lumbar Enlargement of the
Spinal Cord, Cambridge, 1861, Fig. 4.)
ACCESSORY ELEMENTS IN THE NERVE-CENTEES. 55
covering, some distance removed from the cell itself so as to
oe nearly twice the diameter of the cell, which is continuous
with the sheath of the dark-bordered fibres.1 This mem-
brane is always nucleated, and Kolliker has lately shown
hat it is not homogeneous, as was at one time supposed, but
is composed of a layer of very delicate epithelium.8 The
physiological significance of this covering is not apparent.
In the gray matter of the nerve-centres, there is a, finely-
granular substance between the cells, which closely resem-
bles the granular contents of the cells themselves. In addi-
tion to this granular matter, Robin has described new ana-
tomical elements which he has called myelocytes. These
are found in the cerebro-spinal centres, forming a layer near
the boundary of the white substance, and are particularly
abundant in the cerebellum. They exist in the form of free
nuclei and nucleated cells, the free nuclei being by far
the more numerous. The nuclei are rounded or ovoid, with
strongly-accentuated borders, are unaffected by acetic acid,
finely granular, and generally -without nucleoli. The cells
are rounded or slightly polyhedric, pale, clear, or very slightly
granular, and contain bodies similar to the free nuclei. The
free nuclei are from SJ-OQ to -^m of an inch in diameter, and
the cells measure from -g-gVo to 2 0*0 o ? and sometimes 14100 of
an inch.* These elements also exist in the second layer of
the retina.
There has been a great deal of discussion with regard to
the presence or absence of connective-tissue elements in the
cerebro-spinal centres. In the other ganglia, there has never
been any doubt with regard to the presence of connective
tissue in greater or less amount, and in the cerebro-spinal
centres there can hardly be any question of the existence of
an exceedingly delicate stroma, chiefly in the form of stel-
1 SCHULTZE, in STRICKER, Manual of Human and Comparative Histology,
London, 1870, vol. i., p. 173, el seq.
2 KOLLIKER, Elements d'histologie humaine, Paris, 1868, p. 329.
8 LITTRE ET ROBIN, Diclionnaire de medecine, Paris, 1865, Article, Myelocytts.
56 NERVOUS SYSTEM.
late, branching cells, serving, in a measure, to support the
nervous elements.
The blood-vessels of the nerve-centres form an exceed-
ingly graceful capillary net-work with very large meshes.
The gray substance is much richer in capillaries than the
white.
A remarkable peculiarity of the vascular arrangement in
the cerebro-spinal centres has already been described in con-
nection with the lymphatic system. The blood-vessels here
are surrounded by what have been called peri vascular canals,
first described by Robin, and afterward shown by His and
Robin to be radicles of the lymphatic system.1
Composition of the Nervous Substance.
Our knowledge of the chemical constitution of the ner-
vous system is, in many regards, quite unsatisfactory ; but
these tissues contain certain elements that have been very
well determined. The chemical characters of cholesterine,
for example, have long been known to physiologists, as well
as the fact that this principle is a constant constituent of the
nervous substance, united in some way with the other proxi-
mate principles, so that it does not appear in a crystalline
form. Since we demonstrated, in 1862, the relations of
cholesterine to the process of disassimilation, this principle
has assumed its proper place as one of the most important
of the products of physiological waste of the organism. The
origin and function of cholesterine, with the processes for its
extraction from the fluids and tissues of the body, have been
fully considered under the head of excretion.3
Regarding cholesterine as an excrementitious product,
to be classed with principles destined simply to be elimi-
nated from the organism, the nerve-substance proper has
been found to contain the following proximate principles,
the chemical properties of which have been more or less
1 See vol. ii., Absorption, p. 433. 2 See vol. iii., Excretion, p. 267, et seq.
PBOTAGON. 57
accurately determined ; viz., protagon, neurine, fatty matters
combined with phosphorus, and bases combined with peculiar
fatty acids.
Protagon. — This principle was discovered by Liebreich,
and described in 1865.1 Its formula is C116H341O3a]Sr4P. It
may be extracted by the following process : The cerebral
substance is bruised in a mortar, and afterward shaken with
water and ether in a closed vessel. The mixture is then ex-
posed to a temperature of 32° Fahr., and the ethereal layer,
containing cholesterine, is removed. The insoluble mass is
then extracted with alcohol, 85 per cent., at 113°, is again
filtered and exposed to a temperature of 32°. An abundant
precipitate then separates, which is washed with ether and
desiccated in vacuo. The protagon is thus obtained in the
form of a white powder. Since this principle has been de-
scribed in the brain-substance, a compound analogous to, if
not identical with protagon, has been discovered by Her-
mann in the blood-corpuscles.5 In its general and chemical
characters, protagon resembles the albuminoid proximate
principles ; but it presents the remarkable difference, that
the sulphur, which exists in many of the principles of this
class, is replaced by phosphorus.
. — This name has been applied to a rather indefi-
nite principle supposed to represent the albuminoid element
of the nervous tissue ; but its characters as a proximate con-
stituent of the nerve-substance have never been well deter-
mined. Robin and Yerdeil place neurine among the proxi-
mate principles of probable existence. According to these
authors, this is the organic substance of the brain, not soluble
1 LIEBREICH, Ueber die chemische Beschaffenheit der Gehimsiibstanz. — Annalen
der Chemie und Pharmacie, Leipzig und Heidelberg, 1865, Bd. cxxxiv., S. 29,
(t seq.
8 HERMANN*, Ueber das Vorlcommen von Protagon im Blute. — Archiv fur
pathologische Anatomic und Physiologic, Berlin, 1866, S. 36, ft seq.
58 NERVOUS SYSTEM.
in alcohol. When incinerated it does not leave a residue
impregnated with phosphoric acid, like the cerebral fatty
matter.1 According to more recent investigations, particu-
larly those of Liebreich, neurine is a derivative of protagon.
The neurine of Liebreich is obtained by boiling protagon for
twenty-four hours in baryta-water, when there is formed the
phospho-glycerate of baryta, and a new base, neurine.8 It is
evident that this substance cannot properly be regarded as a
well-determined proximate principle.
"We have already alluded to the experiments of Wurtz
upon the synthesis of neurine.3 These observations are im-
portant as a step toward the synthesis of organic nitrogen-
ized principles, but they do not afford an example of the
actual formation of a characteristic nitrogenized constituent
of the nerve-tissue. They simply show that the chlorohy-
drate of an artificial organic compound presents crystals
identical with the chlorohydrate of neurine extracted from
the brain.4
Cerebral Fatty Principles. — Researches into the compo-
sition of the fatty principles found in the nervous substance
have been so indefinite and unsatisfactory in their results,
that even now they possess but little physiological interest.
In the earlier observations, the fats extracted from the nerve-
tissue were generally combined with cholesterine. This sub-
stance has now been isolated, and the residue contains a
variety of principles, which seem, under physiological condi-
1 KOBIN ET VERDEIL, Traite de chimie anatomique, Paris, 1853, tome iii.,
p. 451.
2 LIEBREICH, loc. cit. ; and, Journal de Vanatomie, Paris, 1866, tome iii., p. 654.
3 See vol. iii., Excretion, p. 195, foot-note.
4 WURTZ, Sur Vldentite de la nevrine artifiddle avec la nevrine naturdle. —
Comptes rendus, Paris, 1868, tome Ixvi., p. 772, et seq. Wurtz obtained neurine
by the reaction of trymethylamine upon monochlorohydric glycol. He found
that the chlorohydrate of trymethyloxethylammonium was identical with the
chlorohydrate of neurine prepared with neurine from the brain. By neurine,
Wurtz undoubtedly means the principle described under that name by Liebreich.
COBPOBA AMYLACEA. 59
tions, to be intimately united with the nitrogenized substance,
presenting one of the exceptions to the general law that fats
exist in the body, uncombined, except with each other. In
tliis mass of fatty matter, we can determine the presence of
oleine, margarine, and stearine ; but these are combined with
other fats, fatty acids, etc., the remarkable peculiarity of most
of which is, that they contain a certain proportion of phos-
phorus. These peculiar principles have received a variety
of names, as they have been described more or less minutely
by different observers, such as cerebrine, white and red
phosphorized fat, lecithene, cerebric acid, and cerebrate of
soda. The application of most of these names is very indefi-
nite, and when we say that the substances are, in greatest
part, peculiar to the nervous tissue, and that they contain
phosphorus, we have stated about all that is physiologically
important. Lecithene is a neutral phosphorized fat, proba-
bly composed of a number of different fatty principles, which
exists, not only in the nervous substance, but in the blood,
bile,1 and the yolk of egg.3 Its chemical history has no
physiological interest. The same may be said of cerebric
acid, the cerebrate of soda, oleo-phosphoric acid and its com-
pounds with soda and lime.
Corpora Amylacea. — Little rounded or ovoid bodies, about
•j-sVcr of an inch in diameter, have been described by Yir-
chow and others 3 as existing normally in the corpora stria ta,
the medulla oblongata, and some other portions of the
cerebro-spinal system. With regard to the actual compo-
sition of these bodies, there is considerable difference of
opinion. Yirchow and many others regard them as identi-
cal with starch, the granules of which they certainly resemble
very closely, being of the same shape, with borders well
1 See voL iii., Excretion, p. 262.
8 LITTRE ET ROBIN, Dictionnaire de medecine, Paris, 1865, Article, Lecithene.
8 VIRCHOW, Cellular Pathology, Philadelphia, 1863, p. 320.
, Human Physiology, Philadelphia, 1867, p. 66.
60 NERVOUS SYSTEM.
defined, frequently presenting concentric laminae and a hilum.
When carefully treated, first with a solution of iodine and then
with a little sulphuric acid, they assume a blue color. Some
observers consider them as analogous to cellulose, others have
supposed that they are formed of cholesterine, and others
regard them as nitrogenized bodies. * These points are of
purely anatomical interest, and the physiological relations
of these bodies are not known.
Regeneration of the Nervous Tissue.
"We do not propose to discuss fully the question of the
regeneration of nerves after section or even excision of a
portion of their substance, though it is one of great patho-
logical interest ; but in this connection will refer to some
experiments recently made, in which it appears that it is pos-
sible for certain of the most important of the nerve-centres
to be regenerated and their function restored after extir-
pation.
"With regard to the simple reunion of nerves after division
or excision, it has long been known that this takes place in
the human subject and in the inferior animals, with restora-
tion of function.3 The new tissue connecting the divided
extremities of the nerve seems to pass through the regular
stages of development observed in the nerve-tissue of the
embryon, the gelatinous fibres, or the fibres of Remak, first
appearing, and these being subsequently developed into true
nerve-tubes. In this process there is not a cicatrix, as in
the skin or muscular tissue, but a development of new ele-
ments possessing the anatomical and physiological charac-
ters of the original structure.
1 VIRCHOW, he. tit.
LITTRK ET ROBIN, Dictionnaire de medecine, Paris, 1865, Article, Cor-
puscle.
2 LAVERAN, Recherches experimentales sur la regeneration des nerfs, These,
Strasbourg, 1867. This memoir contains an elaborate review of the earlier ex-
periments upon the regeneration of nerves, with some original observations of
much interest.
REGENERATION OF THE NERVOUS TISSUE. 61
The fact of the speedy and complete reunion of divided
nerves has been taken advantage of by physiologists in
experiments upon nerves of different functions. Many years
ago, Flourens divided two mixed nerves, the trunks of which
were near each other, and crossed them, connecting the central
end of the one with the peripheral end of the other, and vice
versa. Reunion of the extremities thus attached took place,
and the functions of the paralyzed parts were restored. • The
communication through both nerves was restored and corre-
sponded to the artificial crossing of the nerves. In these
experiments there was complete reunion of the extremities
of different nerves possessing the same general properties.
Flourens then attempted to produce, in the same way, an
anatomical and physiological reunion between the divided
extremities of nerves of different properties, as the pneumo-
gastric and the fifth cervical. At the end of three months
the anatomical reunion was found complete ; but on dividing
the other pneumogastric, to ascertain if the function of the
first had been restored, the animal manifested the symptoms
that follow division of both pneumogastrics, and died in two
days.1 These experiments have lately been repeated and
extended by Gluge and Thiernesse,8 Philipeaux and Yul-
pian,3 and others, with more definite results. Gluge and
Thiernesse, Schiff,4 and Landry 6 failed to observe restoration
1 FLOURENS, Recherches experimentales sur les proprietes et les functions du
gysteme nerveux, Paris, 1842, p. 266, et seg.
2 GLUGE ET THIERNESSE, JSur la reunion des fibres nerveuses sensibles avec les
fibres matrices. — Journal de la physiologic, Paris, 1859, tome ii., p. 686, et seq.
3 PHILIPEAUX ET VULPIAN, Note sur des experiences demontrant que des nerfs
separes des centres nerveux peuvent, apres s^etre alteres completement, se regenerer
tout en demeurant isolts de ces centres, et recouvrer leurs proprietis physiologiques.
— Journal de la physiologie, Paris, 1860, tome Hi., p. 214 ; Recherches experimen-
talessur la reunion bout d boutde nerfs defonctions different^. — Ibid., 1863, tome
vi., p. 421, et seq., and p. 474, et seq.
4 SCHIFF, Remarques sur les experiences de MM. Philipeaux el Vulpian sur la
regeneration des nerfs. — Journal de la physiologic, Paris, 1860, tome iii., p. 217.
5 LANDRY, Reflexions sur les experiences de MM. Philipeaux et Vulpian, rela-
tives d la regeneration des nerfs. — Ibid., p. 218.
62 NEKVOUS SYSTEM.
of the function of nerves of different properties that became
reunited after division. The experiments upon this point
by Gluge and Thiernesse were the most extended, and were
made upon the lingual branch of the fifth pair and the sub-
lingual. In from three to six weeks, the central end of the
sensitive nerve became firmly united with the peripheral end
of the motor nerve, but the physiological union was in no
case observed, except in one experiment in which the central
end of the sublingual was involved in the reunion.1 This
conclusion was arrived at after a failure to obtain move-
ments in the tongue by stimulating the lingual branch of the
fifth above the point of union.
It is evident that these experiments must have an impor-
tant bearing upon our theories concerning the mode of con-
duction of motor stimulus and sensitive impressions by the
different nerves, and they will be referred to again in con-
nection with that part of our subject. At present we can
only refer to the positive results obtained by Philipeaux and
Yulpian, which are in opposition to the negative experi-
ments of the observers cited above. These physiologists
succeeded in uniting, in dogs, the central end of the pneumo-
gastric with the peripheral end of the sublingual, and the
central end of the lingual branch of the fifth with the periph-
eral end of the sublingual, all of the nerves being divided,
and, in the case of the sublingual and the lingual branch of
the fifth, the central end of the motor nerve being torn out.
In these experiments, on exposing the nerves four or five
months after the first operation, irritation applied to the
sublingual below the point of union produced pain, and a
stimulus applied to the lingual branch of the fifth above the
point of union excited movements of the tongue, even after
dividing the nerve above and separating it from the centres,
so that it was impossible for any reflex movements to take
place.8 These facts show that not only does union take
1 GLUGE ET THIERNESSE, he. tit., p. 695.
2 See the memoirs by PHILIPEAUX AND VULPIAN, already cited from the
REUNION OF NERVES OF DIFFERENT PROPERTIES. 63
place in nerves after division, and between the divided ex-
tremities of two different nerves having the same properties,
but that the divided extremity of a motor nerve may be made
to form an anatomical and physiological union with the
divided extremity of a nerve of sensation, and that both
motor and sensitive currents may be conducted through the
fibres at the point of union.
The only remaining point of physiological interest con-
nected with the regeneration of the nervous tissue is in-
volved in the recent observations of Yoit on the regeneration
of the cerebral lobes after removal in a pigeon, and those of
Masius and Yanlair upon the anatomical and functional re-
generation of the spinal cord in frogs.
The experiments recorded by Voit, and his deductions,
are very curious, and have given rise to a great deal of com-
ment and criticism. In one observation, the cerebral lobes
were removed from a young pigeon in the usual way, an
operation very easily performed, and one which we practise
yearly as a class-demonstration. It is particularly stated that
the operation was complete, and that the entire posterior
lobes were removed. Immediately after the operation, the
pigeon presented the condition of stupor ordinarily observed.
As he gradually recovered from this condition, he . began to
execute a number of mechanical movements, which it is un-
necessary to detail fully, in the most extraordinary manner.
The animal continued to improve, ceased the mechanical
movements, and began to fly about, exhibiting timidity when
approached, and, in short, seemed, after a time, to have quite
or nearly returned to the normal condition. One thing,
however, was remarked : the animal never took food (it was
probably kept alive by stuffing, as is frequently done in such
experiments). After five months, the pigeon was killed.
The cranial cavity was found to be filled with a white mass,
occupying the place from which the cerebrum had been re-
J&urnal de la physiologie ; and, VULPIAN, Lemons sur la physiologic generale et
comparee du systeme nerveux, Paris, 1866, p. 280, et seq.
105
64 NERVOUS SYSTEM.
moved. This mass had the consistence of the white substance
of the brain, and presented a perfect continuity with the
cerebral peduncles, which had not been removed. It had
the form of the two hemispheres, presenting a cavity filled
with liquid and a septum. The whole mass consisted of per-
fect primitive fibres of double contour, and, in their meshes,
ganglionic cells.1
This observation is certainly one of the most remarkable
on record, and, from the extraordinary character of its
results, would hardly be accepted for a moment, but for the
established reputation of Prof. Voit. As it is, such an ob-
servation demands full confirmation. It is well known to all
who have been in the habit of removing the cerebral lobes,
that it is absolutely necessary to remove every portion of
their substance, in order to obtain uniform results, and that
this is accomplished sometimes with considerable difficulty.
In demonstrations to a medical class, we have frequently
verified this fact, and have observed recovery, more or less
complete, when but a small portion of the posterior lobes
escaped. This criticism upon the remarkable observation
just detailed is made by Yulpian,2 and its pertinence will be
recognized by every practical physiologist. "We have only
to study the experiments first made by Flourens, to learn
how, in the lower animals, a part of one of the great central
ganglia may gradually assume the function of the whole, after
this function has been interrupted by the first mutilation.3
"We have cited the essential points in this observation
because it has been so extensively commented upon by
physiologists, but it is far from establishing the principle
that a great nervous centre, like the cerebrum, may be ana-
tomically and functionally regenerated after extirpation.
1 C. VOIT, Phenomenes qui suivent Vdblation des hemispheres du cerveau cJiez
les pigeons (Academic des Sciences de Munich], traduit de T allemand par le Dr.
RABUTEAU. — Revue des cours scientifiques, Paris, 1869, tome vi., p. 256.
2 VULPIAN, Archives de physiologic, Paris, 1869, tome ii., p. 802.
3 FLOURENS, Recherches experimentales sur les proprietesel lesfonclions du sys-
teme nerveux, Paris, 1842, p. 100.
REGENERATION OF NERVOUS TISSUE. 65
The general results of the experiments of Masius and
Yanlair upon the regeneration of parts of the spinal cord
in frogs, after loss of a small portion of its substance, show
that such reparation may take place and is attended with
restoration of function. The formation of cells precedes the
development of fibres, and voluntary motion appears in the
parts situated below the lesion, before sensation.1 There are
no instances on record of such regeneration in the human
subject or in the warm-blooded animals.
1 MASIUS ET YANLAIR, Recherches ezperimentoles sur la regeneration anato-
migue et fonctionnelle de la moelle epinere, Bruxelles, 1870.
CHAPTEE H.
MOTOR AND SENSORY NERVES.
Distinct seat of the motor and sensory properties of the spinal nerves — Specu-
lations of Alexander Walker — Views of Sir Charles Bell regarding the func-
tions of the anterior and posterior roots of the spinal nerves — Experiments
of Magendie on the roots of the spinal nerves — Properties of the posterior
roots of the spinal nerves — Influence of the ganglia upon the nutrition of
the posterior roots — Properties of the anterior roots of the spinal nerves —
Recurrent sensibility — Mode of action of the motor nerves — Associated
movements — Mode of action of the sensory nerves — Sensation in amputated
members.
THE physiological property of nerves which enables them
to conduct to and from the centres the impressions, stimulus,
force, or whatever the imponderable nervous agent may be,
is one inherent in the tissue itself, belonging to no other
structure, and is dependent for its continuance upon proper
conditions of nutrition. So long as the nerves maintain these
conditions, they retain this characteristic physiological prop-
erty, which is generally known under the name of irritability.
Aside from the special senses, the sense of temperature,
and of weight, it is known to every one that through the
nerves we appreciate what are called ordinary sensations,
and are enabled to execute voluntary movements. If a
nerve distributed to a part endowed with sensation and the
power of motion be divided, both of these properties are
lost, and can only be regained through a reunion of the di-
vided nerve. Again, it is equally well known that if such
a nerve be exposed in its course and irritated, violent move-
ments take place in the muscles to which it is distributed,
and pain is appreciated, referred to parts supplied from the
MOTOR AND SENSORY NERVES. 67
same source. These facts, which were fully appreciated by
the ancients, show that the general system of nerves is
endowed with motor and sensory properties, the question
being simply whether these be inherent in the same fibres
or belong to fibres physiologically distinct and derived from
different parts of the central system. This question, which
was solved only about half a century ago, will be the first
to engage our attention.
Distinct Seat of the Motor and Sensory Properties of the
Spinal Nerves. — All of the nerves that take their origin
from the spinal cord are endowed with motor and sensory
properties. These nerves supply the whole body, except
the head and other parts receiving branches from the cranial
nerves. They arise by thirty-one pairs from the sides of the
spinal cord, and each nerve has an anterior and a posterior
root. The anatomical differences between the two roots are
that the anterior is the smaller, and ha"s no ganglion. ' The
larger, posterior root presents a ganglionic enlargement in the
intervertebral foramen. Just beyond the ganglion, the two
roots coalesce and form a single trunk. The nerve-fibres in
the two roots are not of the same size, the anterior fibres
measuring on an average about one-fourth more than the
posterior fibres.1 The structure of the ganglia of the poste-
rior roots has already been considered sufficiently in detail.3
It would be unprofitable to discuss the vague ideas of the
older anatomists and physiologists with regard to the proper-
ties of the roots of the spinal nerves, and we can date our in-
formation upon this point from the suggestion of Alexander
Walker, in 1809, that one of these roots was for sensation
alone and the other for motion.3 It is most remarkable,
however, that "Walker, from purely theoretical considera-
1 KOLLIKER, Elements d'histologie humaine, Paris, 1868, p. 339.
2 See page 51.
3 WALKER, New Anatomy and Physiology of the Brain in particular and of
the Nervous System in general — Archives of Universal Science, Edinburgh, 1809,
vol. iii., pp. 173, 174.
68 NEKVOUS SYSTEM.
tions, should have stated that the posterior roots were motor
and the anterior roots sensory, precisely the reverse of the
truth, and should have advanced this view in a publication
as late as 1844.1 In the work alluded to, which contains
some of the most extraordinary pseudo-scientific vagaries
ever published, it is curious to see how near Walker came to
the greatest discovery in physiology since the description of
the circulation of the blood. He gives an account of an ex-
periment as follows : " On opening the spinal canal of a
frog, accordingly, and performing the only operation on a
living animal which he ever has performed, or ever will per-
form, he found that, in perfect conformity with previous
reasoning, irritation of the anterior roots caused motion,
and irritation of the posterior roots caused little or none." '
!N~ow, it does not appear in the work from which this quota-
tion is made at what time this experiment was performed ;
and we have not been able to ascertain that it wras done be-
fore 1811 ; but, correctly interpreted, this observation had
been almost the great discovery. To conclude our review
of the claims of Walker, there can be no doubt of the fact
that he was the first to distinctly assign motion and sensa-
tion to the different roots of the spinal nerves, though he
incorrectly ascribed motor properties to the posterior roots
and sensory properties to the anterior, and brought forward
not one iota of proof in support of his theories.
The claims of Mayo to the discovery of the distinct
properties of the roots of the spinal nerves are very indefi-
nite. He simply states, long after the publication of the
experiments of Magendie, that the "remarkable analogy
which exists between the fifth nerve and the spinal nerves
1 WALKER, The Nervous System, anatomical and physiological : in which the
functions of the various parts of the brain are for the first time assigned, and to
which is prefixed some account of the author's earliest discoveries, of which the
more recent doctrine of Bell, Magendie, etc., is shown to be at once a plagiarism, an
inversion, and a blunder, associated with useless experiments, which they have nei-
ther understood nor explained, London, 1844, p. 50, et seg.
* WALKER, op. cit., p. 18.
MOTOR AND SENSORY NERVES. 69
ied me to suppose that the two roots of the spinal nerves
had the same discrepancy of function with the two roots of
the fifth ; and that the ganglionic portion might belong to
sensation, the smaller anterior portion to volition." 1
As we shall see farther on, all discussion relative to pri-
ority in the discovery of the true functions of the roots of the
nerves is confined to the claims of Bell and of Magendie. The
experiments of Miiller3 and others were made after 1822, the
date of the first publication of the experiments of Magendie.
In nearly every. treatise on physiology published since
1822, and in almost all works on the nervous system subse-
quent to that date, the great discovery of the distinct seat
of motion and sensation in the spinal nerves is a scribed to
Sir Charles Bell. The name of Magendie is seldom men-
tioned in this connection, even in France ; and his discov-
eries are supposed to relate chiefly to the seat of sensation
and motion in the different columns of the spinal cord.
It is unnecessary to enlarge upon the importance of the
discovery that the anterior roots of the spinal nerves are
motor, and the posterior, sensory, and that the union of these
two roots in the mixed nerves gives them their double
properties, for we can hardly imagine a physiology of the
cerebro-spinal nervous system without this fact as the starting-
point ; and we have entered, rather more elaborately than
usual, into an historical review of this discovery, from the
fact that nearly all writers have ascribed it to Sir Charles
Bell, and have ignored the claims of Magendie, the real dis-
coverer. In an article published in English, in October,
1868,3 and in French, during the same year,4 we have given
1 MAYO, Outlines of Human Physiology, London, 1827, p. 240.
2 MULLER, Physiologic du systeme nerveux, Paris, 1840, tome i., p. 85, et seq. ;
and, Manuel de physiologic, Paris, 1851, tome i., p. 598, et seq. The experiments
of M tiller were first published in 1831.
3 FLINT, JR., Historical Considerations concerning the Properties of the Roots
of the Spinal Serves. — Quarterly Journal of Psychological Medicine, New York,
1868, vol. ii., p. 625, et seq.
4 Journal de ranatomie, Paris, 1868, tome v.r p. 520, et seq., and p. 575, et seq.
70 NEKVOUS SYSTEM.
an elaborate review of the whole subject, being prompted to
do so by the perusal of what purported to be an exact reprint
of the original pamphlet by Charles Bell.1 This pamphlet
was printed for private circulation in 1811, and was never
published. It has been entirely inaccessible, and its con-
tents were only to be divined by references and quotations
in the subsequent writings of Sir Charles Bell and of his
brother-in-law, Mr. Shaw.
Physiological literature does not present another instance
of the merit of a great discovery resting upon references to
an unpublished pamphlet, which no student could possibly
consult in the original, none of these references, upon close
analysis, proving to be entirely distinct and satisfactory. It
is not to be wondered at, therefore, that in our study of the
origin of one of the greatest discoveries of all ages, a reprint
of the original memoir should be examined with the most
critical care. That this reprint was correct, seemed probable
from a comparison of its text with the quotations from
the original to be found in the writings of Sir Charles Bell
and Mr. Shaw, and from the testimony of reviewers who
claimed to have compared it with the original.8 "Within a
short time, however, an authorized reprint in full, from a
manuscript in the hands of the widow of the author, has ap-
peared in the Journal of Anatomy? This reprint corre-
sponds exactly with the text in the "Documents and Dates"
"When the only reprint of the celebrated pamphlet of Sir
Charles Bell was itself excessively rare, as is the case with
the "Documents and Dates" we thought it desirable to
make long quotations to show the ideas entertained by
1 Documents and Dates of Modern Discoveries in the Nervous System, London,
Jolm Churchill, 1839, p. 37, et seq.
2 The London Medical and Physical Journal, 1829, vol. Ixii., p. 525, and voL
Ixiii., p. 40. The British and Foreign Medico- Chirurgical Review, London, 1840,
vol. ix., p. 98.
3 Reprint of the "Idea of a new Anatomy of the Brain ; submitted for the
Observations of his Friends,'1'1 by CHARLES BELL, F. R. S. E. — Journal of Anatomy
and Physiology, Cambridge and London, 1869, vol. in., p. 147, et seq.
MOTOR AXD SENIORY NERVES. 71
Bell regarding the properties of the two roots of the spinal
nerves ; but now that an authorized reprint can be so readily
consulted, it is only necessary to refer to this to show that
Bell did not at that time regard the anterior roots as motor
and the posterior roots as sensory, but that he thought that
the anterior roots were for both motion and sensation and
the posterior roots presided over "the secret operations of
the bodily frame, or the connections which unite the parts
of the body into a system." l
All the credit which we have to give to Sir Charles Bell
for advances in the anatomy and physiology of the spinal
nerves must cease with the review of the pamphlet of 1811.
In a memoir on the nerves of the head, read before the
Royal Society, July 12, 1821, more than a year before the
publication of the experiments of Magendie, there is no men-
tion of distinct motor and sensitive roots of the spinal nerves,
nor of distinct properties in different portions of the spinal
cord. This paper was republished by Bell, after the pub-
lication of Magendie' s observations, in a work on the nervous
system ; and it is this republication which is most accessible
and most frequently referred to by physiological writers.
The republication avowedly contains " some additional ex-
planations ; " but a careful comparison of it with the original
shows that every portion of it that was susceptible of such
verbal alteration had been modified to make it correspond
with the discovery by Magendie. But, at the same time, the
impression received by the reader is, that it is essentially the
same as the memoir published in 1821.3 'In the controver-
sial condition of the question at the time of this republication,
the alterations and " additional explanations " ought certainly
1 In a paper read before the Medico-Chirurgical Society, in April, 1822, Mr.
J. Shaw gives the date of the first paper by Charles Bell, as 1809. This error is
quoted into many reviews and other publications, but it has been corrected by
Bell himself, and by Mr. A. Shaw. (ALEXANDER SHAW, Narrative of the Discov-
eries of Sir Charles Sell in the Nervous System, London, 1830, p. 14.)
8 CHARLES BELL, The Nervous System of the Human Body, London, 1844, p,
33 et seq.
72 NERVOUS SYSTEM.
to have been distinctly indicated in the text ; but in a reprint
of the paper of 1821, in 1830, there is no indication to the
reader that any change had been made from the original,
though every expression bearing upon the question is made
to correspond with the information derived from the discov-
eries of Magendie.1 This is a subject which we have no
desire to pursue farther than is necessary to vindicate the
1 CHARLES BELL, The Nervous System of the Human Body, embracing the
Papers delivered to the Royal Society on the Subject of the Nerves, London, 1830,
p. 55, et seq.
In the appendix to the work on the Nervous System, published in 1844,
the claim to the discovery of the distinct functions of the anterior and posterior
roots of the spinal nerves is distinctly made by Sir Charles Bell, who refers to
the experiments detailed in the pamphlet of 1811. It will be seen by the fol-
lowing extract, as compared with the extracts which we have made from the
pamphlet, that the statements by Sir Charles Bell as to what wa's contained in
this pamphlet are incorrect and calculated to convey an erroneous idea with
regard to the nature of the observations, printed in 1811, but inaccessible, and
of the deductions made at that time.
" Long before this (1811) I wrote a little book, put it into the hands of my
friends, and had it printed and distributed ; it contained (excuse me in saying it)
this great principle — that a nerve, whatever its nature may be, cannot perform
two functions at once pit cannot convey sensation inward to the sensorium at
the same moment that it carries outward a mandate of the will to the muscles,
whether it be through the means of a fluid, or an ether, or a vibration, or what
you will, that it performs its function. Two vibrations cannot run counter
through the same fibre, and at the same instant ; two undulations cannot go in
different directions through the same tube at the same moment ; and therefore I
conceived that the nerves must be different in their kind. This led me to ex-
periment upon the nerves of the spine ; for I said : ' Where shall I1 be able to find
a nerve with the roots separated? Where shall I be able to distinguish the
properties of a compound nerve ? By experimenting upon the separate roots
of the spinal nerves. ' So, then, taking a fine instrument, the point of a needle,
and drawing it first along one set of roots, and then along the other, I found
that, as I touched one set — the anterior roots — it was like touching the key of
a piano-forte, all the cords, as it were — the muscles — were in vibration ; and
when I touched the other there was pain and struggling. That would not do ;
the animal being alive to sensation, there was confusion here ; and therefore I
struck the animal on the head, and then I made my experiments clearly ; by
which it was shewn, that the roots of these nerves were of different qualities,
one obviously bestowing motion ; and, by inference, the other bestowing scnsi-
bility" (The Nervous System, etc., London, 1844, p. 285).
MOTOR AND SENSORY NERVES. T3
scientific record of the last-named physiologist ; and if the
good taste of these allusions be called in question, we have
only to ask that the review in the Psychological Journal or
in the Joui*nal de Panatomie be consulted, and that the
comparisons there made be verified. The same criticisms of
the alterations in the republished memoirs of Sir Charles
Bell have been made by Yulpian.1 Among English writers,
the relative claims of Bell and Magendie have been correctly
reviewed by a writer in the London Medical and Physical
Journal, in 1829,a and by Elliotson, in 1840.8 Bernard, who
formerly ascribed the discovery to Bell, has lately recognized
fully the claims of Magendie.4
The first publications of Magendie concerning the anat-
omy and the functions of different portions of the nervous
system appeared in the Journal de physiologie, in 1821. In
the first volume of this journal, is a notice of the researches
of Charles Bell on the nerves of the face, with an account
of the observations of Mr. Shaw on the same subject.* Ma-
gendie here states that he repeated the experiments of Bell
with MM. Shaw and Dupuy at Alfort.6 He had not at that
time received the memoir of Bell ; but in a succeeding num-
1 VULPIAN, Lemons sur la physiologic ginirale et comparee du systeme nerveux,
Paris, 1866, pp. 109 and 127.
8 The London Medical and Physical Journal, 1829, voL IxiL, p. 532.
3 ELLIOTSON, Human Physiology, London, 1840, p. 465.
4 BERNARD, Lemons sur la physiologic et la pathologic du systeme nerveux,
Paris, 1858, tome i., p. 20, et seq. Even Bernard, a pupil, and for a long time
the preparateur for Magendie, at one time seemed to regard Sir Charles Bell as
the discoverer of the functions of the roots of the spinal nerves (ibid., p. 25 ; and,
Lemons sur les effete des substances toxigues et medicamenteuses, Paris, 1857, p.
20) ; in a late work, however, in which this whole subject is reviewed, the claims
of Magendie to the discovery are fully recognized (BERNARD, Rapport sur le pro-
gres ct la marche de la physiologic generale en France, Paris, 1867, pp. 12 and
154). Bernard states that he was unable to obtain the original memoir of Bell,
printed in 1811, but finally procured an exact copy, which is probably the reprint
of 1839. (Ibid., p. 155.)
6 CHARLES BELL, Recherches anatomiques et physiologiques sur le system*
nerveux. — Journal de pkysiologie, Paris, 1821, tome i., p. 384, et seq.
6 Loc. tit., p. 387.
74: NERVOUS SYSTEM.
ber of the journal, lie gives a full analysis of it.1 In this
number, also, he speaks of having repeated the experiments.
In the same journal, follows a translation of the experiments
of Mr. Shaw.2 In none of these publications is there any
allusion to the properties of the anterior and posterior roots
of the spinal nerves, nor is there any evidence that either
Bell, Shaw, or Magendie knew any thing about the distinct
seat of motion and sensation in the spinal cord and the spi-
nal nerves.3
In August, 1822, Magendie published his first experi-
ments on the functions of the roots of the nerves.4 Unlike
any of the observations made by Charles Bell on the spi-
nal nerves, these were made upon living animals. The spi-
nal canal was opened, and the cord, with the roots of the
nerves, exposed. The posterior roots of the lumbar and sacral
nerves were then divided upon one side and the wound united
with sutures. The result of this observation was as follows :
" I thought at first that the limb corresponding to the
divided nerves was entirely paralyzed ; it was insensible to
pricking and to the most severe pinching, it also appeared
to me to be motionless ; but soon, to my great surprise, I
saw it move in a very marked manner, although the sensi-
bility was still entirely extinct. A second, a third experi-
ment, gave me exactly the same result ; I commenced to
regard it as probable that the posterior roots of the spinal
nerves might have functions different from the anterior roots,
and that they were more particularly devoted to sensibility." 6
1 BELL, Suite de recherches anatomiques et pliysiologiques sur le systeme nervewx.
— Journal de physiologic, Paris, 1822, tome ii., p. 66, et seq.
2 SHAW, Experiences sur le systeme nerveux. Extrait et traduit de V Anglais
par M. Cairns. — Journal de physiologic, Paris, 1822, tome ii., p. 77, et seq.
3 In the same volume of the journal (p. 363), Magendie gives an account of
Bell's observations on the respiratory nerves of the chest, which were presented
to the Royal Society, May 2, 1822.
4 MAGENDIE, Experiences sur le* fonctions des racines des nerfs rachidiens.—
Journal de physiologic, Paris, 1822, tome ii., p. 276, et seq.
5 Ibid., p. 277.
MOTOR AND SENSORY NERVES. 75
The experiments in which the anterior roots were di-
vided were no less striking :
"As in the preceding experiments, I only made the
division upon one side, in order to have a term of compari-
son. One can conceive with what curiosity I followed the
effects of this division ; they were not at all doubtful, the
limb was completely motionless and flaccid, while it pre-
served a marked sensibility. Finally, that nothing should
be neglected, I divided at the same time the anterior and
the posterior roots ; then followed absolute loss of sensation
and of motion." 1
Prom these experiments Magendie drew the following
conclusions :
" I am following out my researches, and will give a more
detailed account of them in the following number ; it is suf-
ficient for me to be able to announce at present as positive,
that the anterior and the posterior roots of the nerves which
arise from the spinal cord have different functions, that the
posterior seem more particularly devoted to sensibility,
while the anterior seem more especially connected with
motion." 2
In the second note, published in the same volume of the
Joui-nal de physiologie^ Magendie exposed and irritated the
two roots of the nerves, with the following results :
" I commenced by examining in this regard the poste-
rior roots, or the nerves of sensation. The following is the
result which I observed : on pinching, pulling, or pricking
these roots, the animal manifested pain ; but this was not to
be compared as regards intensity with that which was 'de-
veloped if the spinal cord were touched, even lightly, at
the point of origin of the roots. Nearly every time that
the posterior roots were thus stimulated, contractions were
produced in the muscles to which the nerves were distrib-
uted ; these contractions, however, are not well marked,
and are infinitely more feeble than when the cord itself is
1 Ibid., p. 278. ' Ibid., p. 279.
76
NERVOUS SYSTEM.
touched. "When, at the same time, a bundle of the poste-
rior root is cut, there is produced a movement in totality in
the limb to which the bundle is distributed.
" I repeated the same experiments on the anterior roots,
and I obtained analogous results, but in an opposite sense ;
for the contractions excited by the contusion, the pricking,
etc., are very forcible, and even convulsive, while the signs
of sensibility are hardly visible. These facts are, then, con-
firmatory of those which I have announced ; only they seem
to establish that sensation is not exclusively in the posterior
roots, any more than motion in the anterior roots. Never-
theless, a difficulty may arise. When, in the preceding ex-
periments, the roots had been cut, they were attached to the
spinal cord. Might not the disturbance communicated to
the cord be the real cause either of the contractions or of
the pain which the animals experienced ? To remove this
doubt, I repeated the experiments after having separated
the roots from the cord ; and I must say that, except in two
animals, in which I saw contractions when I pinched or
pulled the anterior and posterior roots, in all the other in-
stances I did not observe any sensible effect of irritation
of the anterior or posterior roots thus separated from the
cord." 1
Magendie then goes on to say that, when he published
the note in the preceding number of the journal, he sup-
posed that he was the first who had thought of cutting the
roots of the spinal nerves ; but he was soon undeceived by
a letter from Mr. Shaw, who stated that Bell had divided the
roots thirteen years before. Magendie afterward received
from Mr. Shaw a copy of Bell's essay (" Idea of a New Anat-
omy of the Brain "), and, as will be seen by the following
extract, gave Bell full credit for all his observations :
" It is seen by this quotation from a work which I could
not be acquainted with, inasmuch as it had not been pub-
lished, that Mr. Bell, led by his ingenious ideas concerning
1 Ibid., p. 368.
MOTOR AND SENSORY NERVES. 77
the nervous system, was very near discovering the functions
of the spinal roots; still the fact that the anterior are de-
voted to movement, while the posterior belong more par-
ticularly to sensation, seems to have escaped him ; it is,
then, to having established this fact in a positive manner
that I must limit my pretensions."
Such are the experiments by which the properties of the
roots of the spinal nerves were discovered. From that time,
the fact took its place in science, that the posterior roots are
for sensation and the anterior for motion. Some discussion
has arisen as to whether the anterior roots do not possess a
certain amount of sensibility, called recurrent sensibility,
and this question has engaged the attention of physiologists
within, a few years ; but the distinct functions of the two
roots have never been doubted. We have already seen what
use Bell made of these facts in late editions of his work on
the nervous system. Before the days of anaesthetics, expos-
ing the roots of the nerves in the dog was very laborious,
and painful to the animal, and the disturbances produced by
so serious an operation interfered somewhat with the effects
of irritation of the different roots. But now that the canal
may be opened without pain to the animal, the experiments
are much more satisfactory and have often been repeated by
physiologists. We have frequently, indeed, demonstrated
the properties of the roots of the nerves in public teaching.2
Although, as we have seen, almost all physiological
writers, even in France, regarded Bell as the real discoverer,
Magendie continued to claim that he first positively ascer-
tained the seat of motion and sensation in the spinal nerves.
1 Ibid., p. 371.
9 FLINT, JR., Experiment* on the Recurrent Sensibility of the Anterior Hoots
of the Spinal Nerves. — Xew Orleans Medical Times, 1861, p. 21, et seq.
At the time that this paper was written, we had not had an opportunity of
consulting the original memoir of Sir Charles Bell, and, with others, regarded
him as the discoverer of the functions of the roots of the nerves. We have
also had occasion to modify the views therein expressed concerning the recur-
rent sensibility of the anterior roots.
78 NERVOUS SYSTEM.
In 1823, after reiterating his statements with regard to the
nerves, he extended his researches to the cord itself, and de-
monstrated that the anterior columns were motor and the
posterior columns sensitive.1 In all his subsequent publica-
tions the same statements are made."
Shaw, in his " Narrative," states that, in 1822, Magendie
" admitted that the experiments on the roots of the spinal
nerves, which he had claimed as original, had been performed
many years before by Sir Charles Bell." 3 This is not cor-
rect ; and we have already quoted in full the passage in which
Magendie gives Bell full credit for what he had done, but
expressly states that the fact, that the anterior roots preside
over movement, and the posterior, over sensation, seems to
have escaped him. Shaw also quotes Desmoulins and Ma-
gendie as admitting " that there is no absolute distinction
between the functions possessed by the two roots ; " 4 but, in
doing this, he translates the expression into English incor-
rectly. In the passage referred to, it is stated that " L'isole-
ment des deux proprietes dans chacun des deux ordres de ra-
cines, n'est done pas absolu," which simply means that the
motor roots are not absolutely without sensibility, and the
sensory roots are not absolutely devoid of motor properties.
The experiments of Magendie, made in 1822, must stand
without further question as the first to demonstrate the true
properties of the two roots of the spinal nerves ; and, before
the publication of these experiments, no physiologist had a
correct idea, theoretical or experimental, of the seat of motion
and sensation in these nerves.
1 MAGENDIE, Note sur le siege du mouvement et du sentiment dans le moelle
epinere. — Journal de physiologic, Paris, 1823, tome iii., p. 153, et seq.
2 DESMOULINS ET MAGENDIE, Anatomie des systemes nerveux des animaux d ver-
tebres, Paris, 1825, tome il, p. 777.
MAGENDIE, Precis elementaire de physiologic, deuxieme edition, Paris, 1825,
tome i., pp. 167, 216; et, quatrieme edition, 1836, tome i., pp. 200, 266.
8 ALEXANDER SHAW, Narrative of the Discoveries of Sir Charles Bell in ihA
Nervous System, London, 1839, p. 156.
4 Loc. cit., p. 168.
PROPERTIES OF THE POSTERIOR ROOTS. 79
Properties of the Posterior Roots of the Spinal Nerves. —
It is unnecessary to follow out, from the date of the first
experiments by Magendie to the present day, the observa-
tions that have been made from time to time upon the prop-
erties of the roots of the spinal nerves. For many years, the
difficulties in operating upon animals high in the scale ren-
dered confirmatory experiments somewhat unsatisfactory.
The great German physiologist, J. Miiller, showed, in experi-
ments made upon frogs, in 1831,1 that irritation of the pos-
terior roots produced no convulsive movements ; but he de-
spaired of operating satisfactorily upon warm-blooded animals.
Magendie, in his later experiments,2 and Longet, in experi-
ments performed on dogs, published in 18ttl,s showed verv
satisfactorily that the posterior roots were exclusively sen-
sory, and this fact has been abundantly confirmed by more
recent observations upon the higher classes of animals. ITe
have ourselves frequently exposed and irritated the roots of
the nerves in dogs in public demonstrations, in experiments
upon the recurrent sensibility of the anterior roots,4 and in
another series of observations upon the properties of the
spinal cord, which will be referred to hereafter.
The remarkable anatomical peculiarity of the posterior
roots, which they have in common with all of the exclusively
sensitive nerves, is the presence of a ganglion. While we
have no distinct idea of the function of these ganglia in con-
nection with the transmission of impressions from the pe-
riphery to the centres, it has been shown to have a remark-
1 MULLER, Nouvelles experiences sur Teffet que produit rirritation mechaniqut
et galvanique sur les ratines des nerfs spinaux. — Annales des sciences natureUes,
Paris, 1831, tome xxiii., p. 100, et seq.
2 MAGEXDIE, Lecons sur les fonctions et les maladies du systeme nerveux, Paris,
1841, tome ii., p. 52, et seq., quatrieme lecon, 3 mai, 1839.
3 LOXGET, Recherches pathologiques et experimentales sur les prcprittes et let
fonctions des faisceauz de la moelle epinere et des racines des nerfs rachidiens. —
Archives generales de medecine, Paris, 1841, tome Ivi., p. 168, et seq.
4 FLINT, JR., Experiments on the Recurrent Sensibility of the Anterior Roots of
the Spinal Nerves. — New Orleans Medical Times, 1861, p. 21, et sen.
106
80 NERVOUS SYSTEM.
able influence upon the nutrition of the nerves after their
division. Operating upon the second cervical nerves, in
which the ganglia can be reached without exposing the spi-
nal cord, Waller has demonstrated the following interesting
facts : *
When the roots are divided between the ganglion and the
cord, the central end of the anterior root, attached to the
cord, preserves its normal structure, while the peripheral end
in a few days becomes degenerated, the tubes filled with
granular matter, etc., and, in short, undergoes those changes
observed in all nerves separated from their centres. On the
other hand, in the posterior roots, the end attached to the
cord undergoes degeneration, and the peripheral end, the
one to which the ganglion is attached, preserves its normal
histological characters. From these experiments, which have
been confirmed and somewhat extended by Bernard,9 it is
concluded that the ganglia of the posterior roots have an in-
fluence over the nutrition of the sensitive nerves, in the same
way as the centres influence the nutrition of the motor
nerves which emanate from them. These points are- inter-
esting, as showing the existence of centres attached to the
sensory system of nerves, which have, as far as we know,
a purely trophic influence over tho nerves, while the active
centres to which the motor nerves are attached regulate, to
a certain extent, the nutrition of the nerves, and also are
capable of generating nerve-force. We do not know that the
ganglia of the roots of sensitive nerves have any function
except as trophic centres.
Properties of the Anterior Roots of the Spinal Nerves. —
The same experiments that demonstrated that the posterior
roots of the spinal nerves are sensitive showed that the ante-
rior roots are motor. If the two roots be exposed in an
1 WALLER, Comptes rendus, Paris, 1857, tome xliv., p. 168.
2 BERNARD, Lemons sur la physiologic et la pathologic du systeme nerveux,
faris, 1858, tome i., p. 235, et seg.
RECURRENT SENSIBILITY. 81
animal just killed, no convulsive movements are produced
by stimulating the posterior roots ; but if the anterior roots
be irritated, movements of the most violent character occur,
confined to those muscles to which the filaments of the roots
are distributed. There has never been any doubt upon this
point since the experiments of Hagendie ; and it is now uni-
versally admitted by physiologists, that the motor properties
of the mixed nerves are derived exclusively from their ante-
rior roots of origin from the spinal cord. The question has
arisen, however, whether the anterior roots be not also en-
dowed with sensibility, notably less in degree than the poste-
rior roots, but still marked and invariable. The sensibility
observed in the anterior roots is abolished by section of the
posterior roots ; and this property, which is thought to be
derived from the posterior roots, has been called recurrent
sensibility.
Recurrent Sensibility. — We have seen, in reviewing the
history of the discovery of the distinct function of the roots
of the spinal nerves, that even in the earliest experiments by
Magendie, it appeared that the anterior roots possessed sen-
sibility in a certain degree, though it was insignificant as com-
pared with the sensibility of the posterior roots. In his later
experiments, Magendie formularized these facts, and an-
nounced that the anterior roots were sensitive as well as
motor, but less sensitive than the posterior roots, and that
this sensibility was abolished when the posterior roots were
divided.1 Later still, he failed to demonstrate this sensibility
of the anterior roots ; but it was finally shown that this oc-
curred in animals exhausted from pain and loss of blood, and
that the anterior roots were really sensitive under normal
conditions.3 Longet claims to have discovered, in 1839, what
1 MAGENDIE, Lemons sur les fonctions et les maladies du sysleme nerveux, Paris,
1841, tome ii., pp. 63, 78, quatrieme legon, 3 mai, 1839, cincjuieme lepon, 8 mai,
1839..
2 MAGEXDIE, Note sur la sensibilite recurrente ; Extrait des comptes
Paris, juin, 1847, tome xxiv., p. 3.
82 NERVOUS SYSTEM.
is now known as the recurrent sensibility of the anterior
roots, and to have communicated his views to Magendie ; '
but the publications on the subject and the testimony of
Bernard,2 who witnessed all the experiments in the labora-
tory of the College of France, as well as the observations of
Magendie, in 1822, leave no doubt that he was the first to
note the sensibility of these roots.
The experimental facts with regard to the recurrent sen-
sibility are very simple. If the two roots of a spinal nerve
be exposed, and if the animal be allowed to recover, by a
few hours' repose, from the shock of the operation, irrita-
tion of the posterior root will produce pain and the general
movements incident to it, but no localized contractions of
muscles; and irritation of the anterior root will produce
contraction of certain muscles and a certain amount of pain,
always less, however, than the pain resulting from stimula-
tion of the posterior roots. If the anterior root be divided,
the end attached to the cord will be found completely insen-
sible, but the peripheral end will manifest the same sensibili-
ty as the undivided root ; showing that the sensory proper-
ties of the anterior roots are not derived from the cord. If
the posterior root be divided, the sensibility of the anterior
root is instantly abolished ; showing that the sensibility of
the anterior root is recurrent, being derived from the poste-
rior root through the periphery. With regard to these facts
there can be no doubt, and we ourselves verified them in a
series of experiments published in 1861.3 Experiments have
simply demonstrated the fact that the recurrent sensibility
comes through the periphery, without actually showing any
recurrent fibres ; and division of a mixed nerve after the
nnion of the two roots deprives the anterior root of its scn-
1 LONGET, Traite de physiologic, Paris, 1869, tome Hi., p. 115.
2 BERNARD, Lemons sur la physiologic et la pathologic du syst&me nerveux, Paris,
1858, tome i., p. 35.
3 FLINT, JR., Experiments on the Recurrent Sensibility of the Anterior Roots of
ffte Spinal Nerves.— New Orleans Medical Times, 1861, p. 21, et seq.
RECURRENT SENSIBILITY. 83
sibility, showing that the recurrent fibres, if they exist, must
turn back near the periphery.1
The question now arises with regard to the exact mech-
anism of recurrent sensibility. The explanation offered by
Magendie and Bernard is, that there are actually fibres re-
turning from the posterior to the anterior roots ; that these
fibres are, of course, sensitive, and that irritation of the an-
terior roots is propagated toward the periphery, and returns
to the centres through the posterior roots. This explanation
satisfies all of the experimental conditions, and is further
sustained by the microscopical examinations of Schiff, and
of Philipeaux and Yulpian. It will be remembered that the
ganglia of the posterior nerves, after division of these roots,
have the remarkable power of preserving the anatomical
integrity of the fibres to which they are attached. Now,
it has been shown by Schiff that, after division of the pos-
terior roots beyond the ganglia, the anterior roots contain
altered fibres, which he believes come from the posterior
roots, and give to these roots their sensibility. Philipeaux
and Yulpian, in experiments on the regeneration of nerves,
showed that the peripheral ends of the sublingual and facial
nerves remained sensitive after division, and that after ten
or fifteen days, in the midst of a great mass of degenerated
fibres, were a few that possessed their normal characters.3
The bearing of these facts will be better understood by re-
ferring back to the experiments of Waller on the influence
of the ganglia over the nutrition of sensitive nerves.3
Dr. Brown-Sequard offers a different explanation of the
pain developed upon irritation of the anterior roots. He
believes this to be due entirely to cramp or convulsive con-
traction of the muscles.4 This may be accepted, perhaps, as
1 BERNARD, Systeme nerveux, Paris, 1858, tome i., p. 28.
8 VULPIAX, Lemons sur la physiologic generate ef. comparee du systeme ncrveux,
Paris, 1866, p. 150. ' See page 80.
4 BROWN-SKQUARD, Course of Lectures on the Physiology and Pathology of the
Central Nervous System, Philadelphia, 1860, p. 8.
84 NERVOUS SYSTEM.
a partial explanation ; for there can be no doubt of the fact
that violent muscular action, produced independently of vo-
lition, is more or less painful ; but it does not explain the
great sensibility sometimes observed when the muscular
contraction is comparatively feeble. There can be hardly
any doubt that the explanation offered by Magendie, and
sustained by the ingenious histoiogical observations cited
above, is in the main correct.
Mode of Action of the Motor Nerves. — Having estab-
lished the anatomical distinction between the motor and
sensory nerves, it becomes necessary to study the differences
in the mode of action of these two kinds of nervous con-
ductors. In the first place, it is evident, taking the nerves
and their roots as we find them in, the organism in a normal
condition, that certain fibres act from the centres to the pe-
riphery, conducting motor stimulus, while others act from
the periphery to the centres, conducting sensory impres-
sions; but within a few years, certain experiments have
raised the question, whether sensory fibres may not be made
to conduct the motor stimulus, and vice versa. The experi-
ments to which we allude have already been referred to in
connection with the regeneration of nerves ; 1 and they show
that when a sensory and a motor branch, situated near
enough together, be divided, and the peripheral extremity
of one be connected with the central extremity of the other,
after a time union will take place, and the motor filaments
will conduct sensory impressions, and the sensory filaments
will conduct the motor stimulus. This is a most curious
and interesting experimental fact ; but it is no argument
against the distinct seat of motion and sensation in the ner-
vous system.
As regards the motor nerves, the force, whatever it may
be, generated in the centres, is conducted from the centres
to the peripheral distribution of the nerves in the muscles,
1 See page 62.
MODE OF ACTION OF THE MOTOR NERVES. 85
and is here manifested by contraction. Their mode of ac-
tion, therefore, is centrifugal. "When these motor filaments
are divided, the connection between the parts animated by
them and the centre is interrupted, and motion in these
parts, in obedience to the natural stimulus, becomes impossi-
ble. But, while we cannot induce generation of nerve-force
in the centres by the direct application of any agent to
them, this force may be imitated by stimulation applied to
the nerve itself. A nerve that will respond to direct stimu-
lation is said to be excitable ; but this property does not ex-
tend throughout the entire conducting motor system. For
example, we shall see when we come to study the properties
of the encephalon, that certain fasciculi capable of conduct-
ing the motor stimulus from the centres to the muscles are
not affected by direct stimulation, and seem to be inexcit-
ablc.
If a motor nerve be divided, galvanic, mechanical, or
other stimulation applied to the extremity connected with
the centres produces no effect ; but the same stimulation
applied to the extremity connected with the muscles is fol-
lowed by contraction. The phenomena indicating that a
nerve retains its physiological properties are always mani-
fested at its peripheral distribution, and do not essentially
vary when the nerve is stimulated at different points in its
course. For example, stimulation of the anterior roots near
the cord produces contraction in those muscles to which
the fibres of these roots are distributed ; but the same effect
follows stimulation of the nerve going to these muscles in
any part of its course.
As far as their physiological action is concerned, the dif-
ferent nerve-fibres are entirely independent, and the rela-
tions which they bear to each other in the nervous fasciculi
and in the so-called anastomoses of nerves involve simple
contiguity. If we compare the nerve-force to galvanism,
each individual fibre seems completely insulated ; and a stim-
ulus conducted by it to muscles never extends to the adjacent
00 NERVOUS SYSTEM.
fibres. That it is the axis-cylinder which conducts and the
medullary tube which insulates, it is impossible to say with
positiveness ; but, as we have already seen, it is move than
probable that the central band is the only conducting ele-
ment. ,
We have incidentally noted the fact that direct stimula-
tion applied to the centres, even when the connection between
these and the muscles is perfect, is incapable of inducing the
generation of nerve-force ; but the generation of a motor
stimulus may be induced by an impression made upon sen-
sitive nerves and conveyed by them to the centres. If, for
example, we isolate a certain portion of the central nervous
system, as the spinal cord, and leave its connections with
the motor and sensitive nerves intact, these phenomena may
be readily observed : An impression made upon the -sensi-
tive nerves will be conveyed to the gray matter of the cord
and will induce the generation of a motor stimulus by the
cells of this part, which will be conducted to the muscles
and give rise to contraction. As the stimulus, in such ob-
servations, seems to be reflected from the cord through the
motor nerves to the muscles, this action has been called
reflex. These phenomena constitute an important division
in the physiology of the nervous system, and will be fully
considered by themselves.
Associated Movements. — It is well known that the action
of certain muscles is with difficulty isolated by an effort of
the will. This applies to sets of muscles on one side of the
body and to corresponding muscles upon the two sides.
For example, it is almost impossible, without great practice,
to move some of the fingers, restraining the movements of
the others ; and the action of certain sets of muscles of the
extremities is always simultaneous. The toes, which are but
little used as the foot is confined in the ordinary dress, are
capable of very little independent action. It is difficult to
move o?ie eye without the other, or to make rapid rotary
ASSOCIATED MOVEMENTS. 8T
movements of one hand, while an entirely different order of
movements is executed by the other ; and instances of this
kind might be multiplied.
In studying these associated movements, the question
arises as to how far they are due to the anatomical relations
of the nerves to the centres and their connections with mus-
cles, and how far they depend upon habit and exercise. "We
can imagine that there are certain sets of nerve-cells, con-
nected with each other by commissural fibres and giving ori-
gin to motor nerves distributed to sets of muscles ; an ana-
tomical arrangement that might render a separate action of
these cells impossible. The anatomy of the nerve-centres
and their connection with fibres are so difficult of investiga-
tion, that demonstrative proof of the existence of such sys-
tems is impracticable ; but this affords a ready explanation
of the fact that we cannot, as a rule, by an effort of the
will, cause a portion only of a single muscle to contract ; yet
some of the larger muscles receive an immense number of
motor nerve-fibres which are probably connected with gray
matter composed of numerous anastomosing cells.
Many of the associated movements are capable of being
influenced to a surprising degree by education, of which no
better example can be found than in the case of skilful per-
formers upon certain musical instruments, such as the piano,
harp, violin, and other stringed instruments. In the tech-
nical study of such instruments, not only does one hand be-
come almost independent of the other, but very complex
associated movements may be acquired. An accomplished
pianist or violinist executes the different scales automati-
cally by a single effort of the will, and frequently pianists
execute at the same time scales with both hands, the action
being entirely opposed to the natural association of move-
ments. Feats of sleight of hand also show how wonderfully
the muscles may be educated, and to what an extent the
power of association and disassociation of movements may
be acquired by long practice.
88 NERVOUS 81' STEM.
Looking at the associated movements in their relations
to the mode of action of the motor nerves, it seems prob-
able that, as a rule, the anatomical relations of the nerves
are such that a motor stimulus, or an effort of the will, can-
not be conducted to a portion only of a muscle, but must act
upon the whole muscle, and the same is true, probably, of
certain restricted sets of muscles ; but the association of
movements of corresponding muscles upon the two sides
of the body, with the exception, perhaps, of the muscles of
the eyes, is due mainly to habit, and may be greatly modi-
fied by education.
Mode of Action of the Sensory Nerves. — The sensory
nerve-fibres, like the fibres of the motor system, are en-
tirely independent of each other in their action; and in
the so-called anastomoses that take place between sensory
nerves, the fibres assume no new relations, except as regards
contiguity.
As motor fibres convey to their peripheral distribution
the stimulus engendered by an irritation applied in any por-
tion of their course, so an impression made upon a sensitive
nerve is always referred to the periphery. A familiar
example of this is afforded by the very common accident of ,
contusion of the ulnar nerve as it passes between the ole-
cranon and the condyle of the humerus. This is attended
with painful tingling of the ring and little finger and other
parts to which the filaments of this nerve are distributed,
without, necessarily, any pain at the point of injury. More
striking examples are afforded in neuralgic affections depend-
ent upon disease or pressure on the trunk of a sensitive
nerve. In such cases, excision of the nerve is often practised,
but no permanent relief follows unless the section be made
between the affected portion of the nerve and the nerve-
centres ; and the pain produced by the disease is always re-
ferred to the termination of the nerve, even after it has been
divided between the seat of the disease and the periphery,
MODE OF ACTION OF THE SENSORY NERVES. 89
leaving the parts supplied by the nerve insensible to direct
irritation. In cases of disease it is not unusual to note great
pain in parts of the skin that are insensible to direct impres-
sions.1 The explanation of this is, that the nerves are par-
alyzed near their terminal distribution, so that an impres-
sion made upon the skin cannot be conveyed to the senso-
riuin ; but that the trunks of the nerves still retain their
conducting power and are the seat of diseased action, produ-
cing pain, which is referred by the patient to the periphery.
In multiplying examples showing the mode of action of
the sensoiy nerves, we may refer to the sensations experi-
enced after certain plastic operations. In the very common
operation of restoring the nose by transplanting skin from
the forehead, after the operation has been completed, the
skin having been entirely separated and cicatrized in its new
relations, the patient feels that the forehead is touched when
the finger is applied to the artificial nose. After a time,
however, the sensorium becomes accustomed to the new
arrangement of the parts, and this deceptive feeling disap-
pears.
There are certain curious nervous phenomena, that are
not without physiological interest, presented in persons who
have suffered amputations. It has been long observed that
after loss of a limb the sensation of the part remains and pain
is frequently experienced referred to the amputated member.
Thus a patient will feel distinctly the fingers or toes after an
arm or a leg has been removed, and irritation of the ends of
the nerves at the stump produces sensations referred to the
missing member. A few years since, we observed a very
striking example of this in a soldier who had suffered ampu-
tation of the leg. While this patient was walking about on
crutches, before the stump had entirely healed, on getting up
suddenly from his seat, he attempted to walk, and put the
stump to the ground, producing considerable injury. His
explanation was, that he felt the foot perfectly, and it was
1 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 178.
90 NEKVOUS SYSTEM.
necessary for him to be constantly on his guard to prevent
such an accident.
A very curious fact has been observed with regard to the
imaginary presence of limbs after amputation, which we have
had ample opportunities of verifying. After a time the
sense of possession of the lost limb becomes blunted, and
may, in some cases, entirely disappear. This may take place
a few months after the amputation, or the sensations may
remain in their full intensity for years. Examples are
reported by Miiller where the sense was undiminished thir-
teen, and, in one case, twenty years after amputation.1 In
a certain number of cases, however, the sense of the inter-
mediate part is lost, the feeling in the hand or foot, as the
case may be, remaining as distinct as ever, the impression
being that the limb is gradually becoming shorter. These
curious facts, noted by M. Gueniot,2 show that the sense of
the limb becoming shorter is observed in about half of the
cases of amputation in which cicatrization goes on regu-
larly ; and in these cases, the patient finally experiences a
feeling as though the hand or foot were in direct contact
with the stump. By careful inquiries among a large num-
ber of patients in military hospitals, we have been enabled
to verify these observations in the most satisfactory manner.
1 MULLER, Elements of Physiology, London, 1840, vol. i., p. 746.
2 GUENIOT, D"une hallucination du toucher (ou heterotophie subjective des extre
mites) particuliere a certains ampules. — Journal de la physiologic, Paris, 1861,
tome iv., p. 416, et seq.
CHAPTEE HI.
GENERAL PROPERTIES OF THE NERVES.
Nervous irritability — Different means employed for exciting the nerves — Disap-
pearance of the irritability of the motor and sensory nerves after exsection .
— Nerve-force — Non-identity of nerve-force with electricity — Rapidity of
nervous conduction — Estimation of the duration of acts involving the nerve-
centres — Action of electricity upon the nerves — Contrasted action of the
direct and the inverse current on closing and opening the circuit — Voltaic
alternations — Induced muscular contraction — Galvanic current from the
exterior to the cut surface of a nerve — Effects of a constant galvanic cur-
rent upon the nervous irritability — Electrotonus, anelectrotonus, and cathe-
lectrotonus— Neutral point — Negative variation.
experiments have been made, especially upon
the cerebro-spinal nerves, with regard to their action under
different kinds of stimulation, the probable nature of the
nervous agent, or nerve-force, the extent and duration of
their excitability and sensibility, etc., which have developed
facts of more or less physiological interest and importance.
As far as the nerves of general sensibility are concerned, the
phenomena of conduction of impressions are essentially the
same in all, if we except certain variations in different
nerves as regards the degree of sensibility. The motor
nerves all respond in the same manner to stimulation ; and
it is upon this portion of the nervous system that the most
important observations have been made. This being the
case, it is evident that the cerebro-spinal nerves, in their
behavior under the experimental conditions above enumer-
ated, possess certain general properties, and that the functions
of special nerves are to be studied, after a full consideration
92 NEKVOUS SYSTEM.
of these general properties, in connection with their anatom-
ical distribution to the different organs in the economy.
The points to be considered, aside from the simple divis-
ion of the nerves into motor and sensory, are as follows :
1. The conditions of excitability and sensibility of the
nerves, or what is known as nervous irritability.
2. The nature of the nervous agent, or the so-called
nerve-force.
3. Certain phenomena following the application of elec-
tricity to the nerves.
Nervous Irritability. — We have already alluded in a
general way to what is known as nervous irritability.1 The
term is used by physiologists to express the condition of
nerves which enables them to respond to artificial stimula-
tion, or to conduct the natural stimulus or external impres-
sions. So long as a nerve retains this property it is said to
be irritable. Of course, while in a normal condition and dur-
ing life, irritability, as applied to nerves, simply means that
these parts are capable of performing their peculiar functions ;
but, after death, for a certain time the nerves will respond to
artificial stimulation ; and it is to this property that the term
"irritability" seems to be most applicable. At a certain
time after death, varying in different classes of animals with
the activity of their nutrition, the irritability of the nerves
disappears. This occurs very soon in warm-blooded animals,
but is later in animals lower in the scale, so that the latter
present the most favorable conditions for experimentation.
Most observations on nervous irritability, indeed, have been
made upon frogs and other cold-blooded animals. Analo-
gous facts have already been noted with regard to the mus-
cular system, although, as we have seen, the irritability of
the muscular tissue is entirely distinct from that of the
nerves.51
Immediately or soon after death, when the irritability of
1 See page 66. 2 See vol. iii., Movements, p. 464.
NERVOUS IRRITABILITY.
93
the nerves is at its maximum, they may be excited by me-
chanical, chemical, or galvanic stimulus, all of these agents
producing contraction of the muscles to which the motor fila-
ments are distributed. Mechanical irritation, simply pinch-
ing a portion of the nerve, for example, produces a single
muscular contraction; but if the injury to the nerve be such
as to disorganize its fibres, that portion of the nerve will
no longer conduct a stimulus. Among the irritants of this
kind, we may cite the extremes of heat and cold. If an ex-
posed nerve be cauterized, a vigorous muscular contraction
follows. The same effect, though less marked, may be pro-
duced by the sudden application of intense cold. Among
chemical reagents, there are some that excite the nerves and
others which produce no effect ; but these are not important
from a physiological point of view. Suffice it to say that
mechanical irritation and the action of certain chemicals are
capable of exciting the nerves ; but that when their action
goes so far as to disorganize the fibres, the conducting power
of these fibres is lost. "While, however, irritation of the
nerve above the point of injury has no effect, stimulation
between this point and the muscles is still followed by con-
traction.
The most convenient method of exciting the nerves in
physiological experiments is by means of electricity, a stimu-
lus more closely resembling the nerve-force than any other,
and one which may be employed without disorganizing the
nerve-tissue, and consequently admits of extended and re-
peated application. The action of electrfcity, however, with
the methods of preparing the nerves and muscles for experi-
mentation, will be fully considered under a separate head.
The irritability of the motor system is entirely distinct
from that of the sensory nerves, and one may be destroyed,
leaving the other intact. This follows almost as a matter of
course upon the fact of the anatomical distinction between
motor and sensory nerves ; but it is interesting to note the
limits of the irritability after death in nerves of different
94: NERVOUS SYSTEM.
properties and the differences in the manner of its disappear-
ance. The woorara-poison, a very curious agent prepared
by the South- American Indians, has the remarkable prop-
erty of paralyzing .the motor nerves, leaving the nerves of
sensation intact. This fact has been demonstrated by Ber-
nard and others by very curious and ingenious experiments.
The poison, like those of animal origin, acts most vigorously
xfter introduction under the skin or absorption from wounds,
and produces no toxic effects when taken into the stomach,
except when introduced in large quantity in fasting animals.
Under the influence of this agent, an animal dies with com-
plete paralysis of the motor system, presenting, among other
phenomena, arrest of respiration. Most of the varieties of
the poison affect only the motor nerves, and do not influence
the action of the heart ; and in animals brought completely
under its influence, artificial respiration will enable the heart
to continue its action, and, in some instances, if this be per-
sisted in, recovery will take place.
The fact that the woorara-poison affects the motor nerves
only has been experimentally illustrated by Bernard, tak-
ing advantage of the reflex functions of the spinal cord to
show the persistence of the irritability of the sensory nerves.
The most striking of these experiments is the following : A
frog is prepared by exposing the nerves in the lumbar re-
gion, and then isolating the posterior extremities by apply-
ing a strong ligature, including the aorta and all the parts
except the nerves ; so that, practically, the only communica-
tion between the posterior extremities and the body is by
the nerves. It is evident, therefore, that if the poison be
introduced under the skin of the body, acting, as it does,
through the blood, it will affect all parts except the poste-
rior extremities ; for the poison acts from the periphery to
the centres, and must circulate in the parts to which the
motor nerves are distributed. If the posterior extremities
be now irritated, the impression is conveyed to the spinal
cord through the sensory filaments of the lumbar nerves,
NERVOUS IRRITABILITY. 95
which are intact ; this gives rise to a stimulus, which is re-
flected back through the motor filaments of the same nerve,
and the ordinary reflex movements are observed in the
posterior extremities. This is to be expected, inasmuch
as the posterior extremities arc removed from the influence
of the poison. If the anterior extremities, which are com-
pletely under the influence of the poison, be now irritated,
no movements are observed in these parts, but they take
place, as before, in the posterior extremities. The mechan-
ism of this action is easily understood. Reflex phenomena,
consisting in the movements of muscles, may be manifested
throughout the entire system, following irritation of a single
part. An impression made upon the surface is conveyed to
the spinal cord, and, if this be sufficiently powerful, motor
stimulus may be sent through all of the anterior roots com-
ing from the cord. The impression made upon the anterior,
or poisoned extremities, is conveyed by the sensory fila-
ments to the cord and is transmitted to the posterior ex-
tremities through their motor nerves, which are intact. The
fact of the transmission of the impression from the anterior
extremities to the cord shows that the poison does not affect
the sensory system.1
In the same way that the woorara-poison paralyzes the
motor nerves, leaving the sensory system intact, other
agents, as anaesthetics, will abolish the sensibility of the
nerves without affecting the motor filaments. This well-
known fact has also been experimentally illustrated by Ber-
nard.3
As we have already intimated in another connection, the
nerves soon lose their irritability after they have been sepa-
rated from the centres.3 This loss of conducting power is
1 BERNARD, Lemons sur la phy&iologie et la pathologie du systeme nerveuz, Paris,
1858, tome i., p. 203, et seq. /-and, Lefons sur les proprietes des tissiis vivantsY
Paris, 1866, p. 254, et seq,
2 BERNARD, TJitorie physiologique de Tanesthesle. — Rente dt& cows scienti-
figues, Paris, 1868-'69, tome vi., p. 383.
3 See page 80.
107
96 NERVOUS SYSTEM.
attended with important structural changes in the nerve-
fibres. The tubes lose their normal appearance, and the
medullary matter becomes opaque and coagulates in large
drops. The axis-cylinder is not so much modified in struct-
ure, but it certainly loses its characteristic physiological
properties.
The excitability of the motor nerves, according to the
observations of Longet, disappears in about four days after
resection.1 Of course, in experiments upon this point, it is
necessary to excise a portion of the nerve to prevent reunion
of the divided extremities ; but when this is done, after the
fourth day, galvanization of the nerve will produce no con-
traction in the muscles, though the latter retain their con-
tractility, as may be shown by the application of direct irri-
tation. This loss of irritability is gradual, and continues,
whether the nerve be exposed and stimulated from time to
time or be left to itself ; and the loss of excitability pro-
gresses from the centres to the periphery. In the researches
of Longet on this subject, it was found that the lower por-
tion of the peduncles of the brain lost their irritability first ;
then the anterior columns of the cord, then the motor roots
of the nerves, and, last of all, the branches of the nerves
near their termination in the muscles.
The sensibility of the sensory nerves disappears from
the periphery to the centres, as is shown in dying animals
and in experiments with ansesthetics. The sensibility is
lost, first in the terminal branches of the nerves, next in the
trunks and in the posterior roots of the spinal nerves, and
so on to the centres.2 "We have often illustrated this fact in
experiments upon the roots of the spinal nerves and in sec-
tion of the large root of the fifth pair within the cranial
cavity. "When an animal is brought so completely under
,the influence of ether that the operation of opening the spi-
nal canal may be performed without inflicting the slightest
1 LONGET, Trade de physiologic, Paris, 1869, tome iii., p. 171.
2 LONfiET, Op. tit., p. 175.
NERVE-FORCE. 97
pain, the posterior roots will be found to be distinctly sen-
sible. TTe have lately been in the habit, in class-demonstra-
tions, of dividing the fifth pair in the cranium without using
an anaesthetic, as the operation is instantaneous and the
effects are much more striking in this way ; but when we
have used an anaesthetic, we could never push the effects
sufficiently to abolish the sensibility of the root of the nerve.
In an animal brought so fully under the influence of ether
that the conjunctiva, supplied with branches of the fifth,
had become absolutely insensible, the instant the instrument
touched the root of the nerve in the cranium, there were
evidences of acute pain. Nothing could more strikingly
illustrate the mode of disappearance of the sensibility of the
nerves from the periphery to the centres.
The nervous irritability may be momentarily destroyed
by severe shock in killing an animal. This is sometimes
illustrated in preparing frogs for experiments on the nerves ;
the shock of killing the frog by decapitation, tearing off
the skin, etc., abolishing the irritability of the nerves for
the moment. The observations of Longet and Masson have
shown, also, that a galvanic shock sufficiently powerful to
destroy life abolishes instantly the excitability of the motor
Nerve-Force. — The so-called nervous irritability, artifi-
cially manifested by the application of a stimulus directly to
the nerve-tissue, enables the nerves to conduct from the cen-
tres to the periphery a force which is generated in the gray
substance. This we may call the nerve-force. Its produc-
tion is one of the most remarkable of the phenomena of
life ; and its essence, or the exact mechanism of its genera-
tion, is one of the problems that has thus far eluded the
investigations of physiologists. We know, however, that in
the operations of the nervous system, the nerves serve sim-
ply as conductors and the nerve-cells generate the nerve-
1 LONGET, Traite de physiologic, Paris, 1869, tome ii., p. 602.
98 NERVOUS SYSTEM.
force. It is evident, also, that nearly all of the so-called
vital phenomena are more or less influenced and controlled
through this wonderful agent ; and throughout our study of
the nervous system, we shall be constantly investigating the
phenomena attending the operation of nerve -force, while
compelled to admit our ignorance of its essential nature.
Non-identity of Nerve-Force with Electricity. — When we
come to study fully the action of electricity upon the nerves,
we shall see that this is by far the most convenient stimulus
for exciting the nervous action, and one by which we closely
imitate the true nerve- force. So great is the similarity, in-
deed, between some of the phenomena produced by the ap-
plication of electricity and those attending the physiological
action of nerves, that some physiologists have regarded the
nerve-cells as generators of an electric current. This hy-
pothesis explains the nature of nerve-force, in so far as it
assimilates it to a force, with the action of which, as artifi-
cially generated, we are more or less familiar. No one at
the present day, however, pretends that the nerve-force has
been demonstrated to be identical with any form of elec-
tricity ; and the question does not now demand extended
discussion.
A series of experiments made by Prevost and Dumas,
in 1823, are worthy of note as showing the absence of a true
electric current in nerves in action ; 1 but these have been
confirmed in later years with apparatus sufficiently delicate
to settle the question beyond a doubt. The most conclusive
experiments on this subject are those of Matteucci and Lon-
get, made upon horses at the veterinary school at Alfort.
These physiologists exposed the sciatic nerves in 'the living
1 PREVOST ET! DUMAS, Memoire sur les phenomenes qui accompagnent la con-
traction de la fibre mu&culaire. — Journal de physiologic, Paris, 1823, tome iii., p.
328. Analogous experiments, with the same results, were made later by Person
(Sur Thypothese des courans electriques dans les nerfs. — Journal de physiologie^
Paris, 1830, tome x., p. 216, el seq.).
RAPIDITY OF NERVOUS CONDUCTION. 99
animal, and, when there was evidently a conduction in both
directions, as evinced by pain and muscular action, failed to
detect the slightest evidence of an electric current with the
most delicate galvanometer that could be constructed. The
fact of the absence of a galvanic current in nerves during
their physiological action was even more strikingly illus-
trated by Matteucci, who demonstrated, in the electric eel,
that although the electric discharges from the peculiar or-
gans of this animal were under the control of the nervous
system, and could be excited by galvanic stimulation of the
proper nerves immediately after death, no galvanic current
existed in these nerves during their physiological action.1
AVhen we abandon the hypothesis of the identity of
nerve-force with electricity, we are compelled to admit that
the agent generated by the nerve-centres is sui generis, and
not to be compared with any force generated outside of liv-
ing organisms or artificially produced by direct stimulation
of the nerves ; but we admit, nevertheless, the fact that
electricity may be generated by animals, as the electric fish-
es, and that electric currents exist in different anatomical
elements of the living body, including the nerves, under cer-
tain conditions. Our study of the nerve-force, then, leaving
its essential nature unexplained, is mainly confined to a de-
scription of its attending phenomena.
Rapidity of Nervous Conduction. — Until within the last
few years, it has been assumed by many that the rapidity of
nervous conduction was one of those problems in human
physiology that could never be satisfactorily resolved ; and
those who have investigated the history of this question,
which dates from before the time of Haller, have often
quoted the words of Miiller, who says, in his great wo^k
on the " Elements of Physiology," that " we shall probably
never attain the power of measuring the velocity of nervous
action ; for we have not the opportunity of comparing its
1 LONGET, Traite de physiologic, Paris, 1869, tome ill, p. 276, et seq.
100 NERVOUS SYSTEM.
propagation through immense space, as we ha VTC in the case
of light." 1
The conjectures of writers before Haller were based upon
the supposed similarity between nervous conduction and the
passage of electricity ; but Haller formed an estimate of the
rapidity of nervous conduction by ascertaining the number
of letters he was able to pronounce in one minute in read-
ing aloud from the " JSneid." a Calculating then the dis-
tance of the nervous course from the brain to the muscles,
he estimated that the nerve-force moved at the rate of about
one hundred and fifty feet in a second.3 This estimate is
not very far from the truth ; at all events, it gives an idea
of the relative slowness of nerve-conduction as compared
with electricity or light, which travels at the rate of many
hundred millions of feet in a second.
The first rigorous estimates of the velocity of the nerve-
current were made in 1850, by Helmholtz,4 and were applied
to the motor nerves. The important and interesting re-
sults of these experiments were arrived at by an ingenious
application of the graphic method, which has since been so
largely improved and extended by Marey, and their accuracy
was rendered possible by the exceedingly delicate chrono-
metric apparatus which has been devised within the last
few years.
It is unnecessary to describe fully the exact methods
employed by Helmholtz and those who immediately followed
in his investigations ; suffice it to say that this distinguished
physiologist and physicist constructed apparatus which,
though somewhat complex, was so accurate as to leave no
doubt as to the reliability of his results. Taking into
account all of the disturbing conditions, and allowing for the
1 MULLER, Elements of Physiology, London, 1840, vol. i., p. 729.
* HALLER, Elementa Physiologice, Lausannse, tomus iv., p. 483.
8 Op. tit., tomus iv., p. 373.
4 HELMHOLTZ, Note sur la vitesse de propagation de Tagent nerveux dans les
nerfs rachidiem. — Comptes rendus, Paris, 1850, tome xxx., p. 204, and, 1851,
tome xxxiii., p. 262.
SAPIDITY OF NERVOUS CONDUCTION. 101
interval of pose, or the length of time between the excitation
of a muscle and the commencement of its contraction,1 he esti-
mated the rapidity of conduction in the motor nerves of the
frog at about eighty-five feet per second.9 The results ob-
tained by Marey upon frogs give a much slower rate of
nervous conduction. These were followed, however, by the
observations of Helmholtz and Baxt on the human subject,
which are, of course, the most interesting of all.
The process devised by Marey is beautifully simple. He
employed, to estimate small fractions of a second, a cylinder
graduated in the following manner: An ordinary tuning-
fork, vibrating, say, five hundred times per second, is so
arranged that a point connected with one of its arms is made
to play against a strip of blackened paper. As the paper
remains stationary, the point makes but a single mark ; but
when the paper moves, as the point vibrates, a line is pro-
duced with regular curves, every curve representing TJ7
of a second. Now, if a lever be attached to a muscle, and
be so arranged as to mark upon the paper, moving at the
same rate, the instant when contraction takes place, it is evi-
dent that the interval between two contractions produced
by stimulating the nerve at different points of its course will
be most accurately indicated ; and if the length of the nerve
between the two points of stimulation be known, the differ-
ence in time will represent the rate of nervous conduction.3
In experiments upon frogs, the leg is prepared by cutting
away the muscles and bone of the thigh, leaving the nerve
attached. The lever is then applied to the muscles of the
leg and the stimulation is applied successively at two points
in the nerve, the distance between them being carefully
measured. The results obtained in this way showed a rate
1 See vol. iii., Movements, p. 472.
8 Comptes rendus, Paris, 1851, tome xxxiii., p. 262.
3 MAREY, Du mouvement dans les fonctions de la vie. — Revue des cours scien-
tijiques, Paris, 1865-'66, tome iii., p. 346, et seq.; and, Du mouvemenf, etc., Paris,
1868, p. 410, et seq.
102 NEKVOUS SYSTEM.
of conduction of from thirty-six to forty-six feet per second ;
but these are not regarded by Marey as invalidating the
estimates by Helmholtz, in view of the various conditions by
which the rapidity of conduction is modified.1
Employing the myograph of Marey, Baxt, in the labora-
tory of Helmholtz, has succeeded in measuring the rate of
nervous conduction in the human subject. In these experi-
ments, the swelling of the muscle during contraction was
limited by enclosing the arm in a plaster-mould, and noting
the contraction through a small opening. By then exciting
the contraction by stimulating the radial nerve successively
at different distances from the muscle, the estimate was
made. The rate in the human subject was thus estimated at
one hundred and eleven feet per second.2 The latest experi-
ments on this subject by Helmholtz and Baxt, in which great
care was taken in the adjustment of the apparatus, showed a
mean of rapidity for the motor nerves, in man, of about two
hundred and fifty-four feet per second. These observations
were made in the summer of 1869 ; and the difference in the
results is in part explained by the fact, which was ascertained
experimentally at that time, that a high temperature in-
creases, and a diminished temperature retards the velocity
of nervous conduction.3 It has been further shown by Munk,
that the rate of conduction is different in .different portions
of the nervous trunk ; the rapidity progressively increasing
as the nerve approaches its termination.4
Helmholtz, Du Bois-Reymond,B Marey, and others, have
1 MAREY, Du mouvement, etc., Paris, 1868, p. 433.
2 BAXT, Versuche uber die Fortpflanzungsgeschwindigkeit der Reizung in den
motorischen Nerven des Menschen. — Monatsbericlde der kdniglich Preussischen
Akademie der Wissenschaften zu Berlin, aus dem Jahre, 1867, Berlin, 1868, S. 233.
3 HELMHOLTZ UND BAXT, Fortpjlanzungsgeschwindigkeit der Erregung in
Bewegungsnerven. — Der Naturforscher, Berlin, 1870, Bd. Hi., S. 230.
4 MUNK, Untersuchunaen uber die Zeitung der Erregung in Nerven. — A rchiv
fur Anatomie, Physiologic, und wissenschaftliche Medecin, Lsipzig, 1864, S. 798,
et seq.
6 Du BOIS-REYMOND, Vitesse de la transmission de la volonte et de la sensation d
iravers les nerfs. — Revue des cours scientifiques, Paris, 1866-'67, tome iv., D. 37
RAPIDITY OF NERVOUS CONDUCTION. 103
noted certain conditions which modify the rate of nervous
conduction. One of the most prominent of these, first ob-
served by Helrnholtz, is due to modifications in temperature.
By a reduction of temperature, in the frog at least, the rate
is very much reduced ; and at 32° it is not more than one-
tenth as rapid as at 60° or TO0. Marey has also noted that
the rate is sensibly reduced by fa'tigue of the muscles.1
The same principle which has led to the determination of
the rate of conduction in motor nerves; viz., an estimation
of the difference in time of the passage of a stimulus applied
to a nerve at two points situated at a known distance from
each other, has been applied to the conduction of sensations.
Hirsch is quoted as having made the first attempt id resolve
this question, in 1851.a He employed the delicate chrono-
metric instruments used in astronomy, and noted the dif-
ference in time between the appreciation of an impression
made upon a part of the body far removed from the brain,
as the toe, and an impression made upon the cheek. This
process admitted of the rough estimate of about one hundred
and eleven feet per second ; an estimate agreeing remarkably
with that of Eaxt for the motor nerves. The later and more
elaborate researches of Schelske show a rapidity of conduction
by the sensory nerves of about ninety-seven feet per second.3
Attempts have been made by Helmholtz, Du Bois-Rey-
mond,4 Marey,5 Bonders,6 and others, to estimate the dura-
1 MAREY, Du mouvement dans lesfonctions de la vie, Paris, 1868, p. 433.
2 LOXGET, Traite de physiologic, Paris, 1869, tome in., p. 291.
3 SCHELSKE, Nene Messungen der Fortpflanzungsgeschwindigkeit des Reizes in
den menschlichfn Nerven. — Archiv fur Anatomic, Physiologic und iribsenchaftUcht
M'.'l.rin, Leipzig, 1864, S. 172.
4 Du BOIS-REYMOND, On the Time required for the Transmission of Volition
and Sensation through the Nerves. A Lecture given at. the Royal Institution. —
BEXCE JOXES, Croonian Lectures on Matter and Force, London, 1868, Appendix
L, p. 97, et seq. ; and, Revue des cours scientijiqaes, Paris, 1866-'67, tome iv., p.
39, et seq.
5 MAREY, Du mouvement dans lesfonetions de la vie, Paris, 1868, p. 442.
6 DOXDERS, Velocity of Cerebral Functions. — The Quarterly Journal of Psy-
chological Medicine, New York, 1869, vol. iii., p. 763, et seq.
104: NERVOUS SYSTEM
tion of acts involving the central nervous system, as the
reflex phenomena of the spinal cord or the operations of the
cerebral hemispheres. These have been partially successful,
or, at least, they have shown that the reflex and cerebral
acts require a distinctly appreciable period of time. This,
in itself, is an important fact ; though the duration of these
acts has not yet been measured with all the accuracy that
could be desired. As the general result of experiments upon
these points, it is found that the reflex action of the spinal
cord occupies more than twelve times the period required
for the transmission of stimulus or impressions through the
nerves.1 Donders found, in experiments on his own person,
that an act of volition required one-twenty-eighth of a sec-
ond, and one of simple distinction or recognition of an im-
pression, one-twenty-fifth of a second.2 These estimates,
however, are merely approximative ; and until they attain
greater certainty, it is unnecessary to describe in detail the
apparatus employed.
The general result of the various observations we have
detailed upon the rate of nervous conduction as applied to
the human subject is, in the first place, that this can be
measured with tolerable accuracy.; second, that it is in no
wise to be compared with the rate of conduction of light or
electricity ; and, finally, that the rate in the human subject
is essentially the same in the motor and sensory nerves, be-
ing, according to the most reliable estimates, about one hun-
dred and eleven feet per second.
Elevation of Temperature in Nerves during their Func-
tional Activity. — There is little to note under this head, ex-
cept the fact that functional activity of the nerves produces
an amount of elevation to temperature in their substance
which can be distinctly demonstrated by sufficiently delicate
thermometric apparatus. Under the head of animal heat,
in another volume, we have given the results of recent ob-
1 Du BOIS-REYMOND, loc. cit. 9 DONDERS, be. cit.
ACTION OF ELECTRICITY UPOX THE XERVES. 105
servations by Lombard, showing an elevation in the tem-
perature of the head during mental exertion.1 The same
facts have lately been observed by Schiff,2 who has also
shown a slight elevation of temperature in nerves during
the conduction of an artificial stimulus.8
•
Action of Electricity upon the Nerves. — A great deal has
been written upon the effects of electricity upon the nervous
system, and facts elicited by experiments upon this subject
are highly important in their bearing on physiology and
pathology. Still, there are numerous observations upon
this subject which have but little importance, in a purely
physiological sense, except that they are curious and inter-
esting. These we do not propose to discuss elaborately ;
but shall confine ourselves chiefiy to those points which bear
directly upon our knowledge of the properties and functions
of the nerves.
The first important fact — to which we have already al-
luded— is, that electricity is the best means that we have of
artificially exciting the nerves. Using electricity, we can
regulate with exquisite nicety the degree of stimulation ;
we can excite the nerves long after they have ceased to re-
spond to mechanical or chemical irritation ; the effects of
different currents can be noted ; and, finally, this mode of
stimulation produces a peculiar and interesting condition of
the parts of the nerve not included between the poles of the
battery. For these reasons, it seems proper to devote some
consideration, in this connection, to the effects of the appli-
cation of this agent to the nerves.
So long as the nerves retain their irritability, they will
respond to an electrical stimulus. Experiments may be
made upon the exposed nerves in living animals or in ani-
1 See vol. in., Animal Heat, p. 415.
2 MORITZ SCHIFF, Recherche* sur Vechauffemeni des nerfs et des centres nerveux
it la suite des irritations semorielles et sensitives. — Archives de physiologic, Paris,
1870, tome iii., p. 5, et seq.
3 Ibid., 1869, tome ii., pp. 157 and 330.
106 NERVOUS SYSTEM.
mals just killed ; and, of all classes, the cold-blooded animals
present the most favorable conditions, an account of the
persistence of nervous and muscular irritability for a consid-
erable time after death. Experimenters most commonly use
frogs, on account of the long persistence of the irritability
of their tissues and the facility with which certain portions
of the nervous system can be exposed. For ordinary experi-
ments upon the nervous conduction, the parts are prepared
by detaching, the posterior extremities, removing the skin,
and cutting away the bone and muscles of the thigh, so as
to leave the leg with the sciatic nerve attached. A frog's
leg thus isolated presents a nervous trunk one or two inches
in length, attached to the muscles, which will respond to the
slightest stimulus. It is by experiments made upon frogs
prepared in this way that most of the important facts rela-
tive to the action of electricity upon the nervous system
have been developed.
It is evident that the galvanic current may be applied to
a nerve so that the direction may, in the one case, follow the
course of the nerve, that is, from the centre to the periph-
ery, and, in the other, be opposite to the course of the nerve.
These currents have been called respectively the direct, or
descending, and the inverse, or ascending.1 "When the posi-
tive pole (the copper) is placed nearer the origin of the
nerve, and the negative pole (the zinc) below this point in
the course of the nerve, the galvanic current follows the
normal direction of the motor conduction, and this is called
the direct current. When the poles are reversed, and the
direction of the galvanic current is from the periphery
toward the centre, it is called the inverse current. It will
be convenient to speak of these two currents respectively as
direct and inverse, in detailing experiments upon the action
of electricity upon the nerves.
The points to be noted with regard to the effects of the
1 The direct current is sometimes called centrifugal, and the inverse, centrip-
etal.
ACTION OF ELECTRICITY UTON THE NERVES. 107
application of electricity to an exposed nerve are the action
of constant currents of different degrees of intensity, the
phenomena observed on making and breaking the circuit,
and the effects of an interrupted current.
During the passage of a feeble constant current through
an exposed nerve, whatever be its direction, there are no
convulsive movements and no evidences of pain. This fact
has long been recognized by physiologists, who at first
limited the effects of electricity upon the nerves to two
periods, one at the making of the circuit and the other at its
interruption. We shall see, however, that the passage of
electricity through a portion of a nervous trunk produces a
peculiar condition in parts of the nerve not included between
the poles of the battery, described by Du Bois-Reymond
under the name of electrotonus ; but the fact that neither
motion nor sensation is excited in a mixed nerve .during the
actual passage of a feeble constant current is not invalidated.
If a sufficiently powerful constant current be passed
through a nerve, disorganization of its tissue takes place, and
the nerve finally loses its excitability, as it does when
bruised, ligatured, or when its structure is destroyed in any
other way.1 It was thought by Galvani, and the idea has
been adopted by Matteucci, Guerard, and Longet,9 that a
current directed exactly across a nerve, so as to pass at right
angles to its fibres, does not give rise to muscular contrac-
tion ; but it is doubtful whether this can be accepted as a
demonstrated fact. Chauveau has found that a transverse
current passed through the exposed facial nerve of a horse
produces well-marked muscular action. He is of the opinion
that the experiments of Galvani and his followers, made upon
frogs, are faulty, inasmuch as the nerve is so small that but
little if any of the galvanic current passes through its sub-
stance, being conducted from one pole to the other through
1 BERNARD, Lerons sur la physiologic et la pathologie dusysteme nerveux, Paris,
1858, tome i.,p. 162.
8 LOXGET, Traile de physiologic, Paris, 1869, tome iii., p. 193.
108 NEKVOUS SYSTEM.
the surrounding moisture, which, in his own experiments,
was carefully removed.1 Longet has noted that pain is pro-
duced by the passage of a transverse current through a sen-
sitive trunk, and that the pain does not seem to be increased
when the poles are separated and the current thus is sent
through a portion of the length of the nerve.2
All who have experimented upon the action of galvanism
upon the mixed nerves have noted the fact alluded to above,
that the phenomena of contraction are manifested only on
closing or breaking the circuit. Take, for example, a frog's
leg prepared with the nerve attached ; place one pole of a
feeble galvanic apparatus on the nerve and then make the
connection, including a portion of the nerve in the circuit,
and usually, a contraction of the muscles will occur when the
circuit is closed, the limb will be quiet during the passage of
the current, and another contraction will take place when
the circuit is broken. "When the parts are freshly prepared,
the contractions take place as described,, whatever be the
direction of the current.3 After a time, however, the ner-
vous irritability becomes somewhat enfeebled, and then it is
observed that the contraction occurs in some instances when
the circuit is closed, and in others when the circuit is broken.
The differences in the time of appearance of these phenom-
ena have been found to depend upon the direction of the
current, and may be formularized as follows :
If the sciatic nerve attached to the leg of a frog, prepared
1 CHAUVEAU, Effets physiologiques de Velectridte. — Journal de la physiologic,
Paris, 1860, tome Hi., p. 298.
2 LONGET, loc. cit., p. 201.
3 A form of galvanic apparatus which we have long used and found very
convenient for these experiments is essentially the one described by Bernard
(Systeme nerveux, Paris, 1858, tome i., p. 144). It consists simply of alternate
copper and zinc wires wound around a piece of wood bent in the form of a
horseshoe and terminating in two platinum points representing the positive and
negative poles. This forms a sort of electric forceps, about eight inches long,
which, when moistened with water slightly acidulated with acetic acid, will give
a current of about the strength required for most of the experiments detailed
above.
ACTIOX OF ELECTRICITY UPOX THE NERVES. 100
In the usual way for such experiments, be subjected to a feeble
galvanic current, there is a time when muscular contraction
takes place only at the instant when the circuit is made ; no
contraction occurring when the circuit is Broken ; and this
occurs only with the direct current ; i. e., when the current
flows toward the periphery, the positive pole being above,
and the negative below. If the poles be reversed, so that
the galvanic current flows from the periphery toward the
centres — the inverse current — contraction of the muscles
occurs only when the circuit is broken and none takes place
when the circuit is closed.
These phenomena are distinct after the irritability of the
parts has become somewhat diminished by exposure or by
electric stimulation of the nerve, but they may occur in per-
fectly fresh parts, when the galvanic current is very feeble.
Usually, when the nervous irritability is at its height, con-
tractions occur both on closing and breaking the circuit ; but
they are more powerful on closing the circuit, for the direct
current, and on breaking the circuit, for the inverse current.
This fact has been noted by all experimenters since the time
of Hitter, by whom the essential characters of these phenom-
ena were first described.1 Hitter was in error in supposing
an antagonistic action of the flexor and extensor muscles
excited by making the circuit with the direct, and breaking
the circuit with the inverse current ; but most of his descrip-
tions of the effects of different currents are remarkably
accurate and have been fully confirmed by late observers.
A very simple experiment made by Matteucci strikingly
illustrates the contrasted action of the direct and the inverse
current. The posterior extremities of a frog are prepared
so as to leave the nerves on the two sides connected together
by a portion of the spinal column. The legs are then placed
each one in a wineglass of water, and a feeble galvanic cur-
rent is passed from one glass to the other. It is evident
1 RITTER, Beytrage zurndhern Kenntniss des Gralvanismiis, Jena, 1805, Bd. ii.,
drittes, viertes und letztes Stuck, S. 132, et seq.
110 NERVOTJS SYSTEM.
that, with this arrangement, the current will pass through
both nerves, being direct for the one and inverse for the
other. In this case, if the irritability of the nerves be not
too intense, ther'e will be a contraction in the leg in which
tho current is direct at the time of making the circuit, while
the other leg will contract when the circuit is broken.1 This
experiment has been modified by Chauveau, and applied to
the two facial nerves in a living horse. A Leyden jar is
very feebly charged with electricity, and the two facials are
exposed. The current is then passed instantaneously through
both the nerves, which gives but a single stimulus and that
corresponds to the time of making the circuit with the con-
stant current. In this experiment, the current is direc't for
one nerve and inverse for the other, and contraction takes
place only in those muscles supplied with the nerve for
which the current is direct.3
The muscular contraction produced by galvanic stimula-
tion of the nerve is more vigorous the greater the extent of
the nerve included between the poles of the battery. This
fact has long been observed, and its accuracy is easily veri-
fied. It would naturally be expected that the greater the
amount of stimulation the more marked would be the mus-
cular action ; and the stimulation seems to be increased in
proportion to the extent of nerve through which the gal-
vanic current is made to pass.
The irritability of a nerve, it is well known, may be ex-
hausted by the repeated application of electricity, whatever
be the direction of the current, and is more or less com-
pletely restored by repose. It is a curious fact, in this con-
nection, that when the irritability of a nerve has been ex-
hausted for the direct current, it will respond to the inverse
current, and vice versa / and it is even more remarkable that
after the irritability has been exhausted by the direct cur-
1 MATTEUCCI, Lemons sur les phenomena physiques des corps vivants, Paris,
1847, p. 233.
8 CHAUVEAU, op. cit. — Journal de la physiologic, Paris, 1860, tome iii., p. 67.
ACTION OF ELECTRICITY UPON THE NERVES. Ill
rent, it is restored more promptly by stimulation with the
inverse current than by absolute repose, and vice versa.
This phenomenon, observed by Yolta, is sometimes known
as " voltaic alternation." * It is very strikingly illustrated in
frogs prepared as above described, with the two posterior
extremities, the nerves attached through a portion of the
spinal cord, placed in vessels of water so tl^at a current may
be simultaneously passed through both nerves, being 'direct
for the one and inverse for the other. As we have already
seen, after a time, contraction occurs only in one leg, for
which the current is direct, on making the circuit, and in the
other, only on breaking the circuit. By repeatedly passing
the current in this way, after a time there will be no con-
traction in either leg, the irritability of the nerves having
become exhausted. If the poles of the battery be now re-
versed, so as to make the inverse current take the place of
the direct, contractions with making and breaking the cir-
cuit will again occur. The irritability may again be ex-
hausted and restored by changing the poles, and this may
be repeated several times with the same preparation.
There can be no doubt with regard to the action of the
direct and inverse currents, as above described, applied to
nerves exclusively motor, as well as to the mixed nerves. In
the mixed nerves separated from the centres, it is evident
that the motor elements only are acted upon ; and it would
be difficult to understand how the action of these currents
could be different when applied to the anterior roots of the
spinal nerves. Longet and Matteucci, however, in their
earlier experiments upon the anterior roots of the spinal
nerves, observed that contraction of muscles took place on
breaking the circuit, with the direct current, and on making
the circuit, with the inverse current ; precisely the opposite
of the phenomena noted in experiments on the mixed
nerves ; and Longet proposed from this to draw a distinc-
tion between the ordinary nerves and those possessed of ex-
1 LONGET, Traite de physiologic, Paris, 1869, tome ill, p. 199.
108
112 NERVOUS SYSTEM.
clusivel j motor properties. The error in these observations,
however, was early pointed out by Rousseau, whose experi-
ments were fully detailed by Bernard before they were pub-
lished separately.1 Rousseau found that when galvanism
was applied to a mixed nerve still connected with its cen-
tres, two galvanic currents were established ; the one taking
the shorter course through that portion of the nerve includ-
ed between the poles of the battery, and the other, called the
" derived current," taking an opposite direction through the
nerves and the tissues. It is evident that the derived cur-
rent would be inverse for the nerve when the shorter cur-
rent is direct, and vice versa. Now if the extent of nerve
included between the poles of the battery be short, the de-
rived current would predominate, and we would seem to
have contraction with the closure of the inverse and the
opening of the direct current. This fact was fully demon-
strated by Rousseau, who devised a little apparatus for neu-
tralizing the derived current, when the phenomena follow-
ing the application of the currents to the nerves attached
were the same as those observed in divided nerves.2 In
1859-'60, shortly after these experiments were published,
we repeated them before a medical class, and have no doubt
as to the accuracy of the results. The experiments of Rous-
seau have since been confirmed by Chauveau ; 8 and Mat-
teucci;4 in his later publications, acknowledges the error of
his first observations, though Longet still adheres to his ori-
ginal deductions.6
Induced Muscular Contraction. — A curious phenomenon
1 ROUSSEAU, in BERNARD, Lemons sur la physiologie et la pathologic du systeme
nerveux, Paris, 1858, tome i., p. 170, et seq.
2 Loc. dt., p. 181.
3 CHAUVEAU, Effeis physiologiques de Peledricite. — Journal de la physiologie,
Paris, 1860, tome in., p. 458, et seq.
4 M ATTEUCCI, Phenomenes physico-chimiques des corps vivants. — Revue des cours
xdentifiques, Paris, 1867-'68, tome v., p. 508.
6 LONGEI, Traite de physwlogie, Paris, 1869, tome iii., p. 187.
INDUCED MUSCULAR CONTRACTION. 113
was discovered by Matteucci, in experimenting upon nervous
and muscular irritability, which has been called " induced
muscular contraction." 1 It was found that if the nerve of a
galvanoscopie frog's leg (the leg prepared with the nerve
attached in the way already described) be placed in contact
with the muscles of another leg prepared in the same way,
galvanization of the nerve giving rise to contraction of the
muscles with which the nerve of the first leg is in contact
will induce contraction in the muscles of both. This ex-
periment may be extended, and contractions may thus be in-
duced in a series of legs, the nerve of one being in contact
with the muscles of another. This illustrates the great deli-
cacy of the galvanoscopie frog's leg, as it will indicate a cur-
rent due to a single muscular contraction, which does not
affect an ordinary galvanometer. It is conclusively proved
that the " induced contraction," as just described, is not due
to an actual propagation of the galvanic current, but to a
stimulus produced by the muscular contraction itself, by the
fact that the same phenomena occur when the first muscular
contraction is produced by mechanical or chemical excitation
of the nerve.
Galvanic Current from the Exterior to ike Cut Surface
of a Nerve. — Before we study certain phenomena presented
in nerves a portion of which is subjected to the action of a
constant galvanic current, it is important to note the fact,
discovered many years ago by Du Bois-Reyrnond, that there
exists in the nerves, as in the muscles,8 a galvanic current
from the exterior to their cut surface.3 This fact has been
confirmed by all who have investigated the subject of electro-
physiology. It has been roughly estimated by Matteucci
that the nerve-current has from one-eighth to one-tenth the
1 MATTEUCCI, Lemons sur les phenomenes physiques des corps vivants, Paris,
1847, p. 288.
* See vol. i., Movements, p. 476.
8 Du BOIS-REYMOXD, Untersuchungen uber thlerhcke Ekklricitdt, Berlin, 1849,
S. 251, ft seq.
114 NERVOUS SYSTEM.
intensity of the muscular current.1 The existence of the
nerve-current has, as far as we know, no more physiological
significance than the analogous fact observed in the muscular
tissue. It is presented in nerves removed from the body, and
has no relation to their functional activity, whether in nor-
mal action or excited by artificial stimulation.
Effects of a Constant Galvanic Current upon the Nervous
Irritability. — Aside from the disorganizing effect upon the
nerves of a powerful constant current, which is due solely
to decomposition of their substance, a feeble current has been
found to exert an important influence upon the nervous
irritability, according to the direction in which the current
is passed. The law in accordance with which this influence
is exerted .is stated by Matteucci as follows :
" A continued electric current passed through a mixed
nerve, the crural or the lumbar, for example, modifies the
excitability of the nerve in a very different manner, accord-
ing to its direction. The excitability is enfeebled by the
passage of the direct current, and, on the contrary, it is pre-
served and augmented, at least within certain limits, by the
inverse current. The time necessary in order that the cur-
rent shall produce this modification is proportionate to the
degree of excitability of the nerve and in inverse ratio to the
intensity of the current. After the breaking of the circuit,
the modification of the nerve tends to cease at a period that
is short in proportion as the excitability of the nerve is great
and the intensity of the current is feeble. This proposition
explains the difference in the electro-physiological effects of
the continued current according to its direction, the well-
known phenomenon of voltaic alternations, and the pe-
riods discovered and specially studied by Marianini and
JSTobili." 3
This law has been carefully studied and formularized, as
above, by Matteucci, but its discovery is attributed by physi-
1 MATTEUCCI, Cours tfehctro-physiologie, Paris, 1858, p. 122. 2 Ibid., p. 30
ELECTKOTONTJS. 115
ological writers to Pfaff.1 After a time, varying with the
excitability of the nerve and the intensity of the current, the
direct current will destroy the nervous irritability, but this
may be restored by repose, or more quickly by the passage
of an inverse current. If the inverse current be passed first
for a few seconds, a contraction follows the breaking of the
circuit ; and this contraction, within certain limits, is more
vigorous the longer the current is passed. At the same time,
the prolonged passage of the inverse current increases the
excitability of the nerve for any kind of stimulus. When
the inverse current has been passed through the nerves for
several hours, breaking of the circuit is followed by very
violent contraction and a tetanic condition of the muscles,
enduring for several seconds.
Electrotorvus, Anelectrotonus, and Catelectrdtonus.
Many years ago, Du Bois-Keymond discovered the curious
and interesting fact, that when a constant galvanic current
is passed through a portion of a freshly-prepared nerve, those
parts of the nerve not included between the poles are brought
into a peculiar condition. While in this state, the nerve
will deflect the needle of a delicate galvanometer and its ex-
citability is modified.9 The deflection of the needle, in this
instance, is not due to the normal nerve-current, for it occurs
when the galvanometer is applied to the surface of the nerve
only. It is due to an electric tension of the entire nerve, in-
duced by the passage of a current through a portion of its
extent. This condition is called electrotonus. The phe-
nomena thus produced have been most elaborately studied by
Pfliiger, who further recognized a peculiar condition of that
portion of the nerve near the anode, or positive pole, differing
from the condition of the nerve near the cathode, or negative
pole. 2s ear the anode,'the excitability of the nerve is dimin-
1 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 194.
8 Du BOIS-REYMOND, Utitersuchungen uber thierische Elektricitat, Berlin, 1849,
Bd ii., S. 289, et seq.
116 NERVOUS SYSTEM.
ished, and this condition has been called anelectrotonus/
Near the cathode, the excitability is increased, and this con
dition has been called catelectrotomis.2
These varied phenomena have been the subject of ex-
tended investigation by electro-physiologists ; and 'although
they are not to be ranked among the physiological properties
of the nerves, they have considerable pathological and thera-
peutic importance. It is well known, fur example, that elec-
tricity is one of the most efficient agents at our command
for the restoration of the functions of nerves affected with
disease ; and the constant current has, particularly of late,
been extensively and successfully used as a therapeutic agent.
The constant current, in restoring the normal condition of
nerves, must influence, not only that portion included be-
tween the poles of the battery, but the entire nerve ; and
the electrotonic condition, with its modifications, explains
how this result may be obtained. Undoubtedly the sensory
nerves are affected as well as the motor, though we have as
yet but little positive information upon this point. A knowl-
edge of the fact that the constant current diminishes the ex-
citability of the nerve near the anode (anelectrotonos) and
increases it near the cathode (catelectrotonos) may become
important in determining the direction of the current to be
' employed in different cases of disease.
In the present condition of the subject of electro-physi-
ology, it will be unnecessary to do more than to indicate, as
clearly and simply as possible, the laws of the phenomena
attending the passage of a constant current through nerves,
as far as they have been definitively ascertained. For a most
lucid exposition of these laws, the physiological student can-
not do better than to consult a lecture recently published by
Dr. Rutherford, of Edinburgh.3
1 PFLUGER, Untersuchungen uber die Physiologic des Electrotomis, Berlin, 1859,
8. 277, et seq.
* Op. cit., S. 186, et seq.
8 RUTHERFORD, Eledrotonus. — Journal of Anatomy and Physiology, Cambridge
and London, 1868, vol. ii., p. 87, et seq.
ELECTROTONTTS. 117
The phenomena of electrotonus are very simple ; and it
is only when we attempt to construct a theory to account for
these phenomena that the subject becomes obscure. Sup-
pose, for example, that a nerve be exposed in a living ani-
mal, or in one just killed, and a galvanic current be applied
from a Grove's battery, in which about twelve square inches
of zinc are exposed to the action of a liquid containing one
part of ordinary sulphuric acid to eight of water.1 A deli-
cate galvanometer applied to the nerve either above or be-
low the poles will indicate a decided current, much more in-
tense than the tranquil nerve-current between the exterior
and the cut surface. This electrotonic condition exists so
long as the galvanic current is continued ; and, as has been
shown by Matteucci in operating upon the higher animals —
rabbits, dogs, fowls, and sheep — when the galvanic current
has been sufficiently powerful and prolonged, the electroto-
nic condition persists for a certain time after the stimulus
has ceased.3 As we have seen that the muscular contraction
following galvanic stimulation of a nerve is powerful in pro-
portion to the extent of nerve included between the poles
of the battery, so the electrotonic condition increases in
intensity with the length of the nerve subjected to the con-
stant current ; provided, always, that the strength of the
current be slightly increased to compensate the enfeebling
action due to the resistance in the increased length of the
circuit.3
^\Ve do not propose to discuss fully the various theories
that have been advanced in explanation of the phenomena
of electrotonus. Matteucci has made a series of interesting
observations upon conductors formed of very fine wires, one
of platinum and the other of amalgamated zinc, covered with
cotton thread soaked in a neutral solution of sulphate of
1 RUTHERFORD, lor. tit.
8 MATTEUCCI, Origine de Telecirotone des nerfs. — Revue des cours stientifique^
Paris, 1867-'68, tome v., p. 279.
MORGAN, Electro-physiology and Therapeutics, Xew York, 1868, p. 495.
118 NEKVOUS SYSTEM.
zinc. The experiments were then arranged so as to operate
first with the platinum wire and afterward with the zinc, by
passing a galvanic current through a small portion of the
conductor, in the same way as it is passed through a portion
of a nerve. He found that in this way he could produce a
strong electrotonic current in the platinum wire, even at a
distance of more than three feet from the electrodes, while
no such current was observed in the zinc. He remarks that
in the platinum wire " secondary polarities " are produced
very powerfully and rapidly, while these are not developed in
the zinc.1 From these experiments alone, it might seem that
the phenomena of electrotonus, as described by Du Bois-Rey-
mond and others, are to be explained entirely by the physi-
cal properties of the nerves as conductors of electricity ; but
various observations on the nerves tinder different condi-
tions have conclusively proven the contrary. All observers
are agreed that the electrotonic condition is marked in pro-
portion to the excitability of the nerve, and is either entirely
absent or extremely feeble in nerves that are dead, or have
lost their irritability. If a strong ligature be applied to the
extra-polar portion of the nerve, or if the nerve be divided
and the cut ends brought in contact with each other, the
electrotonic condition is either not observed or is very feeble.
These facts show conclusively that the phenomena of elec-
trotonus depend upon the physiological integrity of nerves.
A dead nerve, or one that has been divided or strongly liga-
tured, may present these phenomena under the stimulation
of a very powerful current (and then only to a slight degree),
when the condition depends upon the purely physical prop-
erties of the nerve as a conductor ; but there is no compari-
son between these phenomena and those observed in nerves
that retain their physiological properties. Were it other-
wise, how could the physiological properties of a diseased
nerve be restored throughout its whole extent by a constant
current passed through a restricted portion, when the exci-
1 Revue dcs court scientifiques, Paris, 1867-'68, tome v., p. 279.
ELECTROTONTTS. 119
lability of the nerve is only manifested at the closing or
opening of the circuit ? '
Anelectrotonus and Catelectrotonus. — It is interesting to
note that when a portion of a nerve is subjected to a moder
ately powerful constant current, the conditions of the extra
polar portions corresponding to the two poles of the battery
are entirely different. ]N"ear the positive pole, or anode, the
excitability of the nerve and the rate of nervous conduction
are diminished. If, however, we have a galvanometer ap-
plied to this portion of the nerve, its electromotive power,
measured by the deflection of the galvanometric needle, is
increased. On the other hand, near the negative pole, or
cathode, the excitability of the nerve is increased as well as
the rate of nervous conduction ; but the electromotive power
is diminished. The above is laid down by Rutherford, as
the law of electrotonus.8 These facts, at least so far as they
relate to the increase of the excitability of the nerve near
the cathode and its diminution near the anode, are partial-
ly explained by Matteucci upon purely physical principles,
depending upon - the electrolytic action of the current, as is
shown by the following experiment :
Two cups are filled, the one with a very feeble alkaline
solution, and the other with an equally weak acid fluid. A
number of galvanoscopic frogs' legs are then rapidly pre-
pared, of which one-half the number is plunged in the alka-
line and one-half in the acid fluid, for from thirty seconds
to one or two minutes. The parts are then removed from
the liquids, and are carefully washed and dried in bibulous
paper. By touching the nerves with a strong solution of
1 It is necessary to note, in this connection, that Matteucci (Joe. cit.) found
that the electrotonic condition in the platinum wire covered with moistened
cotton was affected by a strong ligature in nearly the same way as a living nerve,
when, of course, " the alteration consists principally in the solution of continu-
ity thus produced in the moist covering of the metallic thread."
2 RUTHERFORD, Electrotonus. — Journal of Anatomy and Physiology, Cambridge
and London, 1868, vol. ii., p. 98.
120 NERVOUS SYSTEM.
common salt, which is a powerful excitant for the nervous
irritability, the nerves that had been exposed to the alkaline
solution produced more powerful and prompt contractions
than those exposed to the acid. Now the electrolytic action
of a constant current tends to the accumulation of hydrogen
and an alkali near the cathode, and oxygen and an acid near
the anode ; and by this, Matteucci explains the increase of
excitability in catelectrotonus and the diminished excita-
bility in anelectrotonus.1 As regards this question, we have
only to say, as in the case of general electrotonus, that the
conditions are susceptible of a partial explanation on purely
physical grounds ; but precisely how far the unexplained
physiological properties of the nerves are involved, it is im-
possible to say.
Neutral Point. — The anelectro tonic condition, on the
one hand, and the catelectrotonic condition at the other
pole of the battery, are marked in extra-polar portions of
the nerve, and are to be recognized as well in that portion
through which the current is passing; but between the
poles, is a point where these conditions .meet, as it were,
and where the excitability is unchanged. This has been
called the neutral point. When the galvanic current is of
moderate strength, this neutral point is about half-way be-
tween the poles. " When a weak current is used, the neu-
tral point approaches the positive pole, while in a strong
current, it approaches the negative pole. In other words, in
a weak current the negative pole rules over a wider territory
than the positive pole, whereas in a strong current the posi-
tive pole prevails." a
Negative Variation.— There remains one curious phe-
nomenon, discovered by Du Bois-Beymond, which depends
1 MATTEUCCI, PMnomenes physico-chimiques des corps vivants. — R?vue des
cours scientifigues, Paris, 1867-'68, tome v., p. 579.
8 RUTHERFORD, loc. cit., p. 92.
ELECTROTO2OJS. 121
upon the action of a rapidly-interrupted current applied to
an excitable nerve. If a galvanometer be applied to a liv-
ing nerve so as to indicate by its deviation the normal, or
tranquil nerve-current, a rapidly-interrupted current of elec-
tricity passed through a portion of the nerve, it is well
known, produces a tetanic condition of the muscles. If we
now watch the needle of the galvanometer, it will be ob-
served to retrograde, and will finally return to zero,, indi-
cating that the proper nerve-current has been overcome.
This will be observed to a slight degree under the influence
of mechanical or chemical stimulation of the nerve, the
proper nerve-current being diminished, but generally not
abolished. This variation of the needle under the influence
of the tetanic condition has been called negative variation.1
We do not yet know that it has any important physiological
or pathological significance.
1 Du BOIS-REYMOXD, Untersuchungen uber thierische Ekktridtat, Berlin, 1849,
Bd. il, S. 425, et seq.
CHAPTEE IV.
SPINAL NERVES MOTOR NERVES OF THE EYEBALL.
Special nerves coming from the spinal cord — Cranial nerves — Anatomical classi-
fication— Physiological classification — Motor oculi communis (third nerve)
— Physiological anatomy — Properties and functions — Influence upon cer-
tain muscles of the eyeball — Action of the inferior oblique muscle — Influ-
ence upon the movements of the iris — Patheticus, or trochlearis (fourth
nerve) — Physiological anatomy — Properties and function — Action of the
superior oblique muscle — Motor oculi externus, or abducens (sixth nerve)
— Physiological anatomy — Properties and function.
Spinal Nerves.
WITH a thorough knowledge of the general properties of
the nerves belonging to the cerebro-spinal system, the func-
tions of most of the special nerves are apparent simply from
their anatomical relations. This is especially true of the
spinal nerves; which, in general terms, are distributed to
the muscles of the trunk and extremities, the sphincters,
and' to the integument covering these parts, the posterior
segment of the head, and a portion of the mucous mem-
branes. It is evident, therefore, that an account of the
exact function of each nervous branch would necessitate a
full description, not only of the nerves, but of the muscles
of the body, which is manifestly within the scope only of
elaborate treatises on descriptive anatomy. It is sufficient
to indicate, in this connection, that there are thirty-one pairs
of spinal nerves \ eight cervical, twelve dorsal, five lumbar,
five sacral, and one coccygeal. Each nerve arises from the
spinal cord by an anterior (motor) and a posterior (sensory)
SPINAL NERVES. 123
root ; the posterior roots being the larger, and having a gan-
glion. Immediately beyond the ganglion, the two roots
unite into a single mixed nerve, which passes out of the
spinal canal by the intervertebral foramen. The nerve thus
constituted is endowed with both motor and sensory prop-
erties. It divides outside of the spinal canal into two
branches, anterior and posterior, both containing motor and
sensory filaments, which are distributed respectively to the
anterior and posterior parts of the body. The anterior
branches are the larger, and supply the limbs and all parts
in front of the spinal column.
The anterior branches of the four upper cervical nerves
form the cervical plexus, and the four inferior cervical nerves,
with the first dorsal, form the brachial plexus. The anterior
branches of the dorsal nerves, with the exception of the first,
supply the walls of the chest and abdomen. These nerves
go directly to their distribution, and do not first form a
plexus, like most of the other spinal nerves. The anterior
branches of the four upper lumbar nerves form the lumbar
plexus. The anterior branch of the fifth lumbar nerve and
a branch from the fourth unite with the anterior branch of
the first sacral, forming the lumbo-sacral nerve, and enter
into the sacral plexus. The three upper anterior sacral
nerves with a branch from the fourth form the sacral plexus.
The greatest portion of the fourth anterior sacral is distrib-
uted to the pelvic viscera and the muscles of the anus. The
fifth anterior sacral and the coccygeal are distributed about
the coccyx.
The posterior branches of the spinal nerves are very sim-
ple in their distribution. With one or two exceptions, which
have no great physiological importance, these nerves pass
backward from the main trunk, divide into two branches,
external and internal, and their filaments of distribution go
to the muscles and integument behind the spinal column.
It is further important to note, as we shall have occasion
to do more particularly in connection with the great sym-
124 NERVOUS SYSTEM.
pathetic nerve, that all of the cerebro-spinal nerves anas-
tomose with the sympathetic. This anatomical connection
between the two systems of nerves has great physiological
interest.
Cranial Nerves.
The nerves which pass out from the cranial cavity present
certain differences in their arrangement and general proper-
ties from the ordinary spinal nerves. As we have seen, the
spinal nerves are exceedingly simple, each one being formed
by the union of a motor and a sensory root. The function of
most of them follows as a matter of course when we under-
stand their general properties and anatomical distribution.
Many of the cranial nerves, however, are peculiar, either as
regards their general properties or in their distribution to
parts concerned in special functions. In some of these
nerves, the most important facts concerning their distribu-
tion have only been ascertained by physiological experimen-
tation, and their anatomy is inseparably connected with
their physiology. It would be desirable, if it were possible,
to classify these nerves with reference strictly to their prop-
erties and functions ; but this can be done only to a certain
extent, and we must adopt as a basis those divisions recog-
nized in the best works on anatomy.
The two classifications of the cranial nerves adopted by
most anatomists are the arrangement of Willis 1 and of Som-
mering.3 The first of these is the more common, and in it
the nerves are numbered from before backward in the order
in which they pass out of the skull, making nine pairs.3
1 WILLIS, Cerebri Anatome : cut accessit Nervorum Descriptio et Usm, Lon-
dini, 1664, p. 145, et seq.
2 SOMMERING, De Basi Encephali et Originibus Nervorum, Goettingae, 1778,
p. 69, et seq.
3 Haller adopted the classification of Willis, and his example has been fol-
lowed by nearly all of the later anatomical and physiological writers, but he dis-
cards the tenth pair, the suboccipital, or first cervical nerve, originally reckoned
by Willis with the cranial nerves (HALLER, Elementa Physiologice, Lausannae,
1762, tomus iv., p. 240.)
CRANIAL NERVES. 125
Anatomical Classification of the Cranial Nerve*.
First Pair. — Olfactory ; special nerve of smell.
Second Pair. — Optic ; special nerve of sight.
Third Pair. — Motor oculi communis ; motor nerve die
tributed to all of the muscles of the eyeball, except the ex-
ternal rectus and the superior^ oblique, to the iris, and the
levator palpebrae.
Fourth Pair. — Patheticus, or trochlearis ; a motor 'nerve
sent to the superior oblique muscle of the eye.
Fifth Pair. — A small motor root (nerve of mastication)
distributed to the muscles of mastication, and a large root
(the trifacial), the nerve of general sensibility of the face.
Sixth Pair. — Motor oculi externus, or abducens ; a mo-
tor nerve passing to the external rectus muscle of the eye.
Seventh Pair. — Portio mollis, or auditory, a special nerve
of hearing ; and the portio dura, or facial ; a motor nerve
distributed to the superficial muscles of the face.
Eighth Pair. — Glosso-pharyngeal ; pneumogastric, or par
vagum ; spinal accessory. Three mixed nerves, with quite
extensive distributions.
Ninth Pair. — Sublingual, or hypoglossal ; a motor nerve
distributed to the tongue.1
Physiological Classification.
(a.) Nertes of Special Sense.
Olfactory.
Optic.
Auditory.
Gustatory, comprising a part of the glosso-pharyngeal
and a small filament from the facial to the lingual branch of
the fifth.
1 According to the classification of Sommering, the arrangement is the same
for the first, second, third, fourth, fifth, and sixth. The facial is called the sev-
enth ; the auditory, the eighth ; the glosso-pharyngeal, the ninth ; the pneumo-
gastric, the tenth; the spinal accessory, the eleventh; and the sublingual, the
twelfth.
126 NERVOUS SYSTEM.
(b.) Nerves of Motion.
Nerves of motion of the eyeball; comprising the motor
oculi communis, the patheticus, and the motor oculi externus.
Nerve of mastication, or motor root of the fifth.
Facial, sometimes called the nerve of expression.
Spinal accessory.
Sublingnal.
(c.) Nerves of General Sensibility.
Trifacial, or large root of the fifth.
A portion of the glosso-pharyngeal.
Pneumogastric.
In the above arrangement, the nerves are classified ac-
cording to their properties at their roots. In their course,
some of these nerves become mixed, and their branches are
both motor and sensory, such as the pneumogastric and the
inferior maxillary branch of the trifacial.
The nerves of special sense are but slightly, if at all, en-
dowed with general sensibility ; and, with the exception of
the gustatory nerves, do not present a ganglion on their
roots, in this, also, differing from the ordinary sensory
nerves. They are capable, therefore, of conveying to the
nerve-centres only certain peculiar impressions, such as
odors, for the olfactory nerves ; light, for the optic nerves ;
sound, for the auditory nerves. The proper transmission of.
these impressions, however, involves the action of accessory
organs, more or less complex ; and we will pass over the
properties of these nerves until we come to treat in full of
the special senses.
Motor Oculi Communis (Third Nerve).
The third cranial nerve is the most important of the
motor nerves distributed to the muscles of the eyeball. Its
physiology is readily understood in connection with its dis-
tribution, the only point at all obscure being its relations to
MOTOR OCULI COMMUNIS. 127
the movements of the iris, upon which the results of experi-
ments are somewhat contradictory. As a preface to the
study of the functions of this nerve, it is necessary to de-
scribe its anatomical relations.
Physiological Anatomy. — Like all of the cranial nerves,
this has an apparent origin, where it separates from the en-
cephalon, and a deep origin, which is the last point to which
its fibres can be traced in the substance of the brain ; but
the origin has not the physiological importance attached to
its ultimate distribution.
The apparent origin of the nerve is from the inner edge
of the cms .cerebri, directly in front of the pons Yarolii,
midway between the pons and the corpora albicantia. It
presents here from eight to ten filaments, of nearly equal
size, which soon unite into a single, rounded trunk.
The deep origin of the nerve has been studied by dissec-
tions of the encephalon fresh and hardened by different
liquids. Yulpian, who has made a great number of very
careful dissections of these nerves, has been able to follow
the fibres from their apparent origin into the brain-substance
as tar as the median line.* From the groove by which, they
emerge from the encephalon, the fibres spread out in a fan-
shape, the middle filaments passing inward, the anterior, in-
ward and forward, and the posterior, inward and backward.
As the result of his observations, Yulpian concludes that
the middle filaments pass to the median line, and decussate
with corresponding fibres from the opposite side. The ante-
rior filaments pass forward and are lost in the optic thala-
mus. The posterior filaments pass backward, and decussate
beneath the aqueduct of Sylvius. This apparent decussation
of the fibres of origin of the third nerves is important in
connection with the harmony of action of the muscles of
the eyes and the iris upon the two sides.
1 VULPIAN, Exsai sur Vorigine de plusieurs paires des nerfs craniens, These,
Paris, 1853, p. 10, et seq.
109
128 NERVOUS SYSTEM.
The distribution of the third nerve is very simple. As
it passes into .the orbit by the sphenoidal fissure, it divides
into two branches. The superior, which is the smaller,
passes to the superior rectus muscle of the eye, and certain
of its filaments are continued to the leva tor palpebrse supe-
rioris. The inferior division breaks up into three branches.
The internal branch passes to the internal rectus muscle ;
the inferior branch, to the inferior rectus ; the external
branch, the largest of the three, is distributed to the inferior
oblique muscle, and, in its course, sends a short and thick
filament to the lenticular, or ophthalmic ganglion of the
.sympathetic. It is this branch which is supposed, through
the short ciliary nerves passing from the lenticular ganglion,
to furnish the mofor influence to the iris.
In its course, this nerve receives a few very delicate fila-
ments from the cavernous plexus of the sympathetic and a
branch also from the ophthalmic division of the trifacial.
Properties and Functions of the Motor Oculi Communis.
— Irritation applied to the root of the third nerve in a living
animal produces contraction of thefmuscles to which it is dis-
tributed, but no pain. If the irritation, however, be applied
a little farther on, in the course of the nerve, there are evi-
dences of sensibility, which is readily explained by its com-
munications with the ophthalmic branch of the trifacial. At
its root, therefore, this nerve is exclusively motor, and its
functions are connected entirely with the actic-n of muscles.
These facts have been experimentally demonstrated by Lon-
get * and by Chauveau.2
Most of the important facts bearing upon the functions
of the motor oculi are clearly demonstrable by dividing the
nerve in a living animal, and are illustrated by cases of its
1 LONGET, Traite de pliysiologie, Paris, 1869, tome iii., p. 554.
8 CHAUVEAU, lieckerches physiologiques sur Vorig'me apparente et sur Vorigine
rfalle des nerfs moteurs craniens. — Journal de la physiologic, Paris, 1862, tome
*., p. 274.
MOTOR OCULI OOMMTJNIS. 129
paralysis in the human subject. Heroert Mayo was one of
the first to experiment upon this nerve in animals living or
just killed, but his observations were made chiefly with ref-
erence to the movements of the iris.1 Bernard,3 Longet,8
and all others who have divided the nerve in living animals,
are agreed with regard to the phenomena following its sec-
tion, which depend upon paralysis of the voluntary muscles.
These phenomena are as follows :
1. Falling of the upper eyelid, or blepharoptosis.
2. External strabismus, immobility of the eye, except
outward, inability to rotate the eye on its antero-posterior
axis in certain directions, with slight protrusion of the eye-
ball.
3. Dilatation of the pupil, with a certain amount of in-
terference with the movements of the iris.
The falling of the upper eyelid is constantly observed
after division of the nerve in living animals, and always fol-
lows its complete paralysis in the human subject. An ani-
mal in which the nerve has been divided cannot raise the lid,
but can approximate the lids more closely, by a voluntary
effort. In the human subject, the falling of the lid gives to
the face a very peculiar and characteristic expression. The
complete loss of power shows that the levator palpebrse su-
perioris muscle depends upon the third nerve entirely for its
motor filaments. In pathology, external strabismus is very
frequently observed without falling of the lid, the filament
distributed to the levator muscle not being affected.
1 MAYO, Anatomical and Physiological Commentaries, Number ii., London,
1823, p. 6 ; and, Outlines of Human Physiology, London, 1827, p. 294.
2 BERNARD, Lecons sur la physiologic et la pathologic du systeme nerveux, Paris,
1858, tome ii., p. 204, et seq.
Bernard gives the following directions for division of the third nerve in the
rabbit : A small steel hook is introduced along the external wall of the orbit
into the middle temporal fossa. With the hook the nerve is caught at the ante-
rior extremity of the fold of the dura mater, which is attached to the sella tur-
cica, and torn across. In this operation, there are generally evidences of pain
from the ophthalmic branch of the fifth as it is touched by the instrument
* Loc.ciL
130 NEKVOU3 SYSTEM.
The external strabismus and the immobility of the eye-
ball except in an outward direction are due to paralysis of
the internal, superior, and inferior recti muscles, the external
rectus acting without its antagonist ; a condition which re-
quires no further explanation. These points are well illus-
trated by the experiment of dividing the nerve in rabbits.
If the head of the animal be turned inward, exposing the
eye to a bright light, the globe will turn outward, by the
action of the external rectus ; but if the head be turned out-
ward, the globe remains motionless.1
It is somewhat difficult to note the effects of paralysis of
the inferior oblique muscle, which is also supplied by the
third nerve. This muscle, acting from its origin at the infe-
rior and internal part of the circumference of the base of
the orbit to its attachment at the inferior and external part
of the posterior hemisphere of the eyeball, gives- to the
globe a movement of rotation on an oblique, horizontal axis,
downward and backward, directing the pupil upward and
outward. When this muscle is paralyzed, the superior
oblique, having no antagonist, rotates the globe upward and
inward, directing the pupil downward and outward. The
action of the oblique muscles is observed when we move the
head alternately toward one shoulder and the other. In the
human subject, when the inferior oblique muscle on one side
is paralyzed, the eye cannot move in a direction opposite to
the movements of the head, as it does upon the sound side,
so as to keep the pupil fixed, and the patient has double
vision.2
When all the muscles of the eyeball, except the external
rectus and superior oblique, are paralyzed, as they are by sec-
tion of the third nerve, the globe is slightly protruded, simply
by the relaxation of most of its muscles. An opposite action
is easily observed in a cat with the facial nerve divided, so
that it cannot close the lids. When the cornea is touched,
1 BERNARD, loc. cit.
2 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 556.
MOTOR OCTJLI COMitUfflS. 131
all of the muscles, particularly the four recti, act to draw
the globe into the orbit, which allows the lid to fall slight-
ly, and projects the little membrane which serves as a third
eyelid in these animals.
Observations with regard to the influence of the third
nerve upon the movements of the iris have not been so sat-
isfactory in their results as those relating to the muscles of
the eyeball. It will be remembered that this nerve sends a
filament to the ophthalmic ganglion of the sympathetic, and
that from this ganglion, the short ciliary nerves take their
origin and pass to the iris. The ganglia of the sympathetic
system receive branches both from motor and sensory nerves
belonging to the cerebro-spinal system, and the ophthalmic
ganglion is no exception to this rule. While it is undoubt-
edly true that division of the third nerve affects the move-
ments of the iris, it becomes a question whether this be a
direct influence, or an influence exerted primarily upon the
ganglion, not, perhaps, differing from the general effects
upon the sympathetic ganglia that follow destruction of
their branches of communication with the motor nerves.
As yet we know little of the reciprocal influences of the
cerebro-spinal and the sympathetic system; but some of
the researches of Bernard into the influence of the sym-
pathetic ganglia upon the salivary secretion show that the
submaxillary ganglion, at least, becomes paralyzed, -or loses
its influence over the secretion of the submaxillary gland,
after it has been separated for a certain time from the cere-
bro-spinal system.1 These considerations, however, belong
more properly to the sympathetic system.
The most important experimental observations with re-
gard to the influence of the third nerve on the iris are the fol-
lowing : Herbert Mayo made experiments on thirty pigeons,
living or just killed, upon the action of the optic, the third,
and the fifth nerves on the iris. He states that when the
1 BERNARD, Recherches experimentales sur les nerfs vasculaires et calorifiques. —
Journal de la physiologic,, Paris, 1862, tome v., p. 409.
132 NERVOUS SYSTEM.
third nerves are divided in the cranial cavity in a living
pigeon, the pupils become fully dilated, and do not contract
on the admission of intense light; and, when the same
nerves are pinched in the living or dead bird, the pupils are
contracted for an instant on each injury of the nerves. The
same results follow division or irritation of the optic nerves
under similar conditions ; but when the third nerves have
been divided, no change in the pupil ensues on irritating
the entire or divided optic nerves.1
The above experiments are accepted by nearly all physio-
logical writers ; and the assumption is that the third nerves
animate the muscular fibres that contract the pupil, the con-
traction produced by irritation of the optic nerves being re-
flex in its character. Later observers, however, have carried
their experiments somewhat further. Longet divided the
motor oculi and the optic nerve upon the right side. He
found that irritation of the central end of the divided op-
tic nerve produced no movement of the pupil of the side
upon which the motor oculi had been divided, but caused
contraction of the iris upon the other side. This, taken in
connection with the fact that, in amaurosis affecting one eye,
the iris on the affected side will not contract under the stim-
ulus of light applied to the same eye, but will act when the
uninjured eye is exposed to the light, further illustrates the
reflex action which takes place through these nerves.3
The reflex action by which the iris is contracted is not
instantaneous, like most of the analogous phenomena ob-
served in the cerebro-spinal system, and its operations are
rather characteristic of the sympathetic system and the non-
striated muscular tissue. It has been found, also, by Ber-
nard, in experiments upon rabbits, that the pupil is not
immediately dilated after division of the third nerve. The
method employed by Bernard, introducing a hook into the
1 MAYO, Anatomical and Physiological Commentaries, Number ii., London!
1823, p. 4.
8 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 656.
MOTOE OCULI COMMTJXIS. 133
middle temporal fossa through the orbit and tearing the
nerve, can hardly be accomplished without touching the
ophthalmic branch of the fifth, which produces intense pain,
and is always followed by a more or less persistent contrac-
tion of the pupil. Several hours after the operation, how-
ever, the pupil is generally found dilated, and may slowly
contract when the eye is exposed to the light. In one ex-
periment, this occurred after the eye had been exposed for
an hour. But further experiments by Bernard show that
although the pupil contracts feebly and slowly under the
stimulus of light after division of the motor oculi, it will di-
late under the influence of belladonna, and can be made to
contract by operating upon other nerves. It is well known,
for example, that division or irritation of the fifth nerve
produces contraction of the pupil. This takes place after
division of the third nerve as well as before. Section of the
sympathetic in the cervical region also contracts the pupil,
and this occurs after paralysis of the motor oculi.1 These
facts show that the third nerve is not the only one capable
of acting upon the iris, and that it is not the sole avenue for
the transmission of reflex influences.
Bernard also found that galvanization of the motor oculi
itself did not produce contraction of the pupil, but this re-
sult followed when he galvanized the ciliary nerves coming
from the ophthalmic ganglion.2 Chauveau states, that in
experiments upon horses, he has not observed contraction of
the pupil following galvanization of the motor oculi, though
he has sometimes seen it in rabbits.3 At all events, contrac-
tion is by no means constant ; and when it occurs, it prob-
ably depends upon stimulation of the ciliary nerves them-
selves or irritation of the ophthalmic branch of the fifth, and
not upon stimulation of the trunks of the third pair.
1 BERNARD, Systeme nerveux, Paris, 1858, tome ii., p. 201, et seq.
8 Op at., p. 211.
3 CHAUVEAU, Recherches pkysiologiques sur Torigine apparante et sur Forigine
reelle des nerfs moteurs craniens. — Journal de la physiologic, Paris, 1862, tome
v, p. 274.
134 NERVOUS SYSTEM.
The movements of the iris will be treated of again, in
connection with the physiology of vision ; but we may here
allude to an interesting fact observed by Miiller, which re-
lates to the action of the motores oculorum. When the eye
is turned inward by a voluntary effort, the pupil is always
contracted ; and when the axes of the two eyes are made to
converge strongly, as in looking at near objects, the contrac-
tion is very great.1
The following case, kindly sent for examination by Dr.
Althof, of the New York Eye Infirmary, illustrates, in the
human subject, nearly all of the phenomena following pa-
ralysis of the motor oculi communis in experiments upon
the lower animals :
The patient was a girl, nineteen years of age, with com-
plete paralysis of the nerve upon the left side. There was
slight protrusion of the eyeball, complete ptosis, with the
pupil moderately dilated and insensible to ordinary im
pressions of light. The sight was not affected, but there
was double vision, except when objects were placed before
the eyes so that the axes were parallel, or when an object
was seen with but one eye. The axis of the left eye was
turned outward, but it was not possible to detect any devia
tion upward or downward. Upon causing the patient to
incline the head alternately to one shoulder and the other,
it was evident that the affected eye did not rotate in the
orbit but moved with the head. This seemed to be a case
of complete and uncomplicated paralysis of the third nerve
Patketicus, vr Trochlearis (Fourth Nerve).
Except as regards the influence of the motor oculi coin-
munis upon the iris, the patheticus is to be classed with the
other motor nerves of the eyeball. Its physiology is ex-
tremely simple, and resolves itself into the action of a single
muscle, the superior oblique. It will be necessary, there-
fore, only to describe its origin, distribution, and connections.
1 MULLER, Elements of Physiology ', London, 1840, vol. L, p. 827.
PATHETICUS. 135
Physiological Anatomy. — The apparent origin of the
patheticus is from the superior peduncles of the cerebellum ;
but it may be easily traced to the valve of Yieussens. Ac-
cording to Yulpian, the deep roots, which are covered by
an extremely thin layer of nerve-substance, can be traced,
passing from without inward, to the following parts : One
filament is lost in the substance of the peduncles; other
filaments pass from before backward into the valve' of Yi-
eussens and are lost, and a few pass into the frenulum ; a
few filaments pass backward and are lost in the corpora
quadrigemina ; but the greatest number pass to the median
line and decussate with corresponding filaments from the
opposite side. Yulpian states that this decussation is quite
as distinct as that of the anterior pyramids of the medulla
oblongata, and that he has been able to follow fibres across
the median line on either side.1 The decussation of the
fibres of origin of the fourth nerves has the same physio-
logical significance as the decussation of the roots of the
third.
From this origin, the patheticus passes into the orbit by
the sphcnoidal fissure, and is distributed to the superior
oblique muscle of the eyeball. In the cavernous sinus, it
receives branches of communication from the ophthalmic
branch of the fifth, but these are not closely united with the
nerve. A small branch passes into the tentorium, and one
joins the lachrymal nerve, these, however, being exclusively
sensitive and coming from the ophthalmic branch of the
fifth.2 It also receives a few filaments from the sympathetic.
Properties and Functions of the Patheticus. — Direct ob-
servations upon the patheticus in living animals have shown
that it is motor, and its galvanization excites contraction of
the superior oblique muscle only. These facts have been
1 VULPIAX, Essai sur Torigine de plusieurs paires des nerfs craniens,
Paris, 1853, p. 15.
2 SAPPEY, Traite d'ancdomie descriptive, Paris, 1852, tome ii., p. 209.
136 NEKVOTJS SYSTEM.
ascertained by Longet1 and by Chauveau.3 The question
of the function of the nerve, therefore, resolves itself sim-
ply into the mode of action of the superior oblique muscle.
This muscle arises just above the inner margin of the optic
foramen, passes forward, along the upper wall of the orbit
at its inner angle, to a little cartilaginous ring which serves
as a pulley. From its origin to this point it is muscular.
Its tendon becomes rounded just before it passes through
the pulley, where it makes a sharp curve, passes outward
and slightly backward, and becomes spread out to be at-
tached to the globe at the superior and external part of its
posterior hemisphere. It acts upon the eyeball from the
pulley at the upper and inner portion of the orbit as the
fixed point, and rotates the eye upon an oblique, horizontal
axis, from below upward, from without inward, and from
behind forward. By its action, the pupil is directed down-
ward and outward. It is the direct antagonist of the in-
ferior oblique, the action of which has been described in
connection with the motor oculi communis. "When the pa-
theticus is paralyzed, the eyeball is immovable, as far as
rotation is concerned ; and when the head is moved toward
the shoulder, the eye does not rotate to maintain the globe
in the same relative position, and we have double vision.3
Motor Oculi Externus, or Abducens (Sixth Nerve).
Like the patheticus, the motor oculi externus is distrib-
uted to but a single muscle, the external rectus. Its uses,
therefore, are apparent from a study of its properties and
distribution.
Physiological Anatomy. — The apparent origin of the
sixth nerve is from the groove which separates the anterior
1 LONGET, Traite de physiologic, Paris, 1869, tome Hi., p. 559.
8 CHAUVEAU, Recherches physiologiques sur Vorigine apparante el sur VorigvM
r&elle des nerfs moteurs craniens. — Journal de la physiologic, Paris, 1862, tome v.,
p. 275.
8 See page 130.
MOTOR OCULI EXTERNTTS. 137
corpus pyramidale of the medulla oblongata from the pons
Yarolii, and from the upper portion of the medulla and the
lower portion of the pons next the groove. Its origin at
this point is by two roots : an inferior, which is the larger,
and comes from the corpus pyramidale ; and a superior root,
sometimes wanting, which seems to come from the lower
portion of the pons. All anatomists are agreed that the
deep fibres of origin of this nerve pass to the gray matter
in the floor of the fourth ventricle. Vulpian has followed
these fibres to within about two-fifths of an inch of the me-
dian line, but could not trace them beyond this point.1 It
is not known that the fibres on the two sides decussate.
From this origin, the nerve passes into the orbit by the
sphenoidal fissure, and is distributed exclusively to the ex-
ternal rectus muscle of the eyeball. In the cavernous sinus,
it anastomoses with the sympathetic through the carotid
plexus and Meckel's ganglion. It also receives sensitive
filaments from the ophthalmic branch of the fifth. It is
stated by Longet,a Sappey,8 and others, that this nerve occa-
sionally sends a small filament to the ophthalmic ganglion ;
and it is supposed by Longet that this branch, which is ex-
ceptional, exists in those cases in which paralysis of the mo-
tor oculi communis, which usually furnishes all the motor
filaments to this ganglion, is not attended with immobility
of the iris.
Properties and Functions of the Motor Oculi Externus.
— Direct experiments, the most satisfactory being those of
Longet 4 and of Chauveau,6 have shown that the motor oculi
communis is entirely insensible at its origin, its stimulation
producing contraction of the external rectus muscle and no
1 YULPIAN, Essai sur Vorigine de plusieurs paires des nerfs rachidiens, These,
Paris, 1853, p. 29.
8 LOXGET, Traite de physiologic, Paris, 1869, tome in., p. 561.
3 SAPPET, Traite cTanatomie descriptive, Paris, 1852, tome ii., p. 249.
4 LOXGET, op. tit., tome iii., p. 560.
6 CHAUVEAU, op. cit. — Journal de la physiologic, Paris, 1862, tome v., p. 275.
138 NERVOUS SYSTEM.
pain. The same experiments illustrate the function of the
nerve, inasmuch as its irritation is followed by powerful con-
traction of the muscle and deviation of the eye outward.
Division of the nerve in the lower animals or its paralysis
in the human subject is attended with internal, or converg-
ing strabismus, from the unopposed action of the internal
rectus muscle.
"With regard to the associated movements of the eyeball,
it is a curious ftict that all of the muscles of the eye that
have a tendency to direct the pupil inward or to produce
the simple movements upward and downward ; viz., the in-
ternal, inferior, and superior recti, are animated by a single
nerve, the motor oculi communis, this nerve also supplying
the inferior oblique ; and that each muscle that has a ten-
dency to move the globe so as to direct the pupil outward,
except the inferior oblique ; viz., the superior oblique and
the external rectus, is supplied by a special nerve. The
various movements of the eyeball will be studied more
minutely in connection with the physiology of vision.
CHAPTER Y.
MOTOR NERVES OF THE FACE.
Nerve of mastication (the small, or motor root of the fifth) — Physiological anat-
omy— Deep origin — Distribution — Properties and functions of the nerve
of mastication — Facial nerve, or nerve of expression (the portio dura of the
seventh) — Physiological anatomy — Intermediary nerve of "Wrisberg — De-
cussation of the fibres of origin of the facial — Alternate paralysis — Course
and distribution of the facial — Anastomoses with sensitive nerves — Summary
of the anastomoses and distribution of the facial — Properties and functions
of the facial — Functions of the branches of the facial within the aqueduct
of Fallopius — Functions of the chorda tympani — Influence of various
branches of the facial upon the movements of the palate and uvula — Func-
tions of the external branches of the facial
THE motor nerves of the face are, the small, or motor
root of the fifth, and the portio dura of the seventh, or the
facial. The first of these nerves is distributed to the deep
muscles, those concerned in the act of mastication, and the
second, the facial, supplies the superficial muscles of the face,
and is sometimes called the nerve of expression. These
nerves are not so simple in their anatomy and physiology as
the motor nerves of the eyeball. The nerve of mastication,
at its origin, is deeply situated at the base of the brain, and
is exposed and operated upon with difficulty. It passes out
of the cranium, closely united with one of the great sensitive
branches of the fifth, and its distribution has been most suc-
cessfully studied by experiments in which it is divided in the
cranial cavity. The origin of the facial is also reached with
great difficulty. It communicates with other nerves, and
its physiology has been most satisfactorily studied by di-
140 NEKVOUS SYSTEM.
viding it at its origin or in different portions of its course.
In treating of these nerves, we shall first, as in the case of
the motor nerves of the eye, study their properties at their
roots, noting the phenomena following their galvanization
and section. It will be necessary, also, to describe their ori-
gin and distribution, as far as has been ascertained by dissec-
tion.
Nerve of Mastication (the Small, or Motor Root of the
Fifth).
The motor root of the fifth nerve is entirely distinct from
its sensitive portion, until it emerges from the cranial cavity
by the foramen ovale. It is then closely united with the
inferior maxillary branch of the large root ; but at its origin
it has been shown to be motor, and its section in the cranial
cavity has demonstrated its distribution to a particular set
of muscles.
Physiological Anatomy. — The apparent origin of the
fifth nerve is from the lateral portion of the pons Varolii.
The small, or motor root arises from a point a little higher
and nearer the median line than the large root, from which
it is separated by a few fibres of the white substance of the
pons. The most satisfactory investigations with regard to
the deep origin of the small root are those of Yulpian. Ac-
cording to this observer, the dissections should be made after
the specimen has been kept in alcohol for about fifteen days,
and before the parts are thoroughly hardened. At the point
of apparent origin, the small root presents "from six to eight
rounded filaments. If a thin layer of the pons covering
these filaments be removed, the roots will be found pene-
trating its substance, becoming flattened, passing under the
superior peduncles of the cerebellum, and going to the ante-
rior wall of the fourth ventricle. At this* point, they change
their direction, passing now from without inward, and from
behind forward toward the median line, the fibres diverging
NERVE OF MASTICATION. 141
rapidly. The posterior fibres pass to the median line, and
Yulpian has seen certain of these decussate with fibres from
the opposite side. The anterior fibres pass toward the aque-
duct of Sylvius and are lost. The fibres become changed in
their character when they are followed inward beyond the
anterior wall of the fourth ventricle. Here they lose their
white color, become gray, and present numerous globules of
gray substance between their filaments.1
From the origin above described, the small root passes ,
beneath the ganglion of Gasser, from w^hich it sometimes,
though not constantly, receives a filament of communication,
lies behind the inferior maxillary branch of the large root,
and passes out of the cranial cavity by the foramen ovale.
Within the cranium, the two roots are distinct ; but after the
small root passes through the foramen, it is united by a mu-
tual interlacement of fibres with the sensitive branch.9
The course of the motor root of the fifth possesses little
physiological interest. It is sufficient in this connection to
note that the inferior maxillary nerve, made up of the motor
root and the inferior maxillary branch of the sensitive root,
just after it passes out by the foramen ovale, divides into
two .branches, anterior and posterior. The anterior branch,
which is the smaller, is composed almost entirely of motor
filaments, and is distributed to the muscles of mastication.
It gives off five branches. The first of these passes to be
distributed to the masseter muscle, in its course occasionally
giving off a small branch to the temporal muscle and a fila-
ment to the articulation of the inferior maxillary with the
temporal bone. The two deep temporal branches are dis-
tributed to the temporal muscle. The buccal branch sends
filaments to the external pterygoid and to the temporal
muscle, and a small branch is distributed to the inter-
nal pterygoid muscle. From the posterior branch, which
1 YULPIAN, Essai sur Torigine de plusieurs paires des nerfs craniens, Thfee,
Paris, 1853, p. 21.
2 SAPPEY, Traite cTanatomie descriptive, Paris, 1852, tome ii., p. 233.
142 NERVOUS SYSTEM.
is chiefly sensitive, but contains some motor filaments,
branches are sent to the mylo-hyoid muscle, and to the an-
terior belly of the digastric. In addition, the motor branch
of the fifth sends filaments to the tensor muscles of the ve-
lum palati.
The above description shows, in general terms, the dis-
tribution of the nerve of mastication, without taking into
consideration its various anastomoses, the most important
of which are with • the facial. Physiological experiments
have shown that the buccinator muscle receives no motor
filaments from the fifth, but is supplied entirely by the facial.
Mayo found that pinching the branch of the fifth which
penetrates the buccinator muscle produced no action upon
it.1 Longet has galvanized the buccal branch of the fifth
without producing contraction of this muscle, which always
contracts upon galvanizing the facial.2 The buccal branch
of the fifth sends motor filaments only, to the external ptery-
goid and the temporal, its final branches of distribution be-
ing sensitive and going to integument and mucous mem-
brane.
In another volume we have given a table of the muscles
of mastication, with a description of their action.3 It will
be seen by this table that the following muscles depress
the lower jaw ; viz., the anterior belly of- the digastric,
the mylo-hyoid, the genio-hyoid, and the platysma myoides.
Of these, the digastric and the mylo-hyoid are animated by
the motor root of the fifth ; the genio-hyoid is supplied by
filaments from the sublingual ; and the platysma myoides, by
branches from the facial and from the cervical plexus. All
of the muscles which elevate the lower jaw and move it lat-
erally and antero-posteriorly ; viz., the temporal, masseter,
and the internal and external pterygoids, the muscles most
1 MAYO, Anatomical and Physiological Commentaries, Number il, London,
1823, p. 8.
8 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 663.
8 See vol. ii., Digestion, p. 147, et seq.
NEBVE OF MASTICATION. 143
actively concerned in mastication, are animated by the mo-
tor root of the fifth.
Properties and Functions of the Nerve of Mastimtion. —
The anatomical distribution of the small root of the fifth
nerve points at once to its function. Charles Bell, whose
ideas of the nerves were derived almost entirely from their
anatomy, called it the nerve of mastication, in 1821, though
he does not state that any experiments were made with re-
gard to its function.1 All anatomical and physiological
writers since that time have adopted this view. It would be
difficult, if not impossible, to galvanize the root in the cra-
nial cavity in a living animal ; but its galvanization, prob-
ably in an animal just killed, has been shown by Longet,
before 1 842, to determine very marked movements of the
lower jaw.2 Longet states in his work on physiology that
no contractions of the muscles of mastication are produced
when the large root of the fifth alone is galvanized. The
experiments demonstrating this fact were made on horses
and dogs, operating upon the roots of the nerves after re-
moving the cerebral lobes.3 Chauveau also found that gal-
vanization of the small root of the fifth produced contrac-
tion of the muscles which elevate the lower jaw sufficiently
sudden and violent to break sometimes, in old horses, little
fragments from the irregular surfaces of the teeth.*
The above experiments are sufficient to show the physio-
logical properties of the small root, which is without doubt
solely a nerve of motion.
1 BELL, On the Nerves; giving an Account of some Experiments on their
Structure and Functions, which lead to a New Arrangement of the System. —
Philosophical Transaction^ London, 1821, Part i., p. 417.
8 LONGET, Anatomic et physiologic du systeme ncrveux, Paris, 1842, tome iL,
p. 190.
3 LOXGET, Traite de physiologic, Paris, 1869, tome iii., p. 562.
4 CHAUVEAU, Recherches physiologiques sur Vorigine apparante et sur Foriffine
r'edle des nerfs moteurs craniens. — Journal de la physiologic, Paris, 1862, tome
v., p. 276.
110
144: NEKVOTJS SYSTEM.
The observations upon the division of the fifth pair in
the cranial cavity, made by Fodera, Mayo, Magendie, Ber-
nard, and others, are most interesting in connection with the
functions of its sensitive branches, and will be referred to in
detail in treating of the properties of the large root. In ad-
dition to the loss of sensibility following section of the entire
nerve, Bernard has noted carefully the effects of division of
the small root, which cannot be avoided in the operation.
In rabbits, the paralysis of the muscles of mastication upon
one side, and the consequent action of the muscles upon the
unaffected side only, produce, a few days after the opera-
tion, a remarkable change in the appearance of the incisor
teeth. As the teeth in these animals are gradually worn
away in mastication and reproduced, the lower jaw being
deviated by the action of the muscles of the sound side, the
upper incisor of one side and the lower incisor of the other
touch each other but slightly and the teeth are worn uneven-
ly. This makes the line of contact between the four incisors,
when the jaws are closed, oblique instead of horizontal.1 "We
have often divided the fifth pair in the cranial cavity in rab-
bits, by the method employed by Magendie and Bernard,
and have repeatedly verified these observations.
There is little left to say with regard to the functions of
the motor root of the fifth nerve, in addition to our descrip-
tion of the action of the muscles of mastication, contained in
the volume on digestion,8 except as regards the action of the
filaments sent to the muscles of the velum palati. In deg-
lutition, the muscles of mastication are indirectly involved.
This act cannot be well performed unless the mouth be
closed by these muscles. When the food is brought in con-
tact with the velum palati, muscles are brought into action
which render this membrane tense, so that the opening is
adapted to the size of the alimentary bolus. These muscles
1 BERNARD, Lemons sur la physiologic et la pathologic du systeme
Paris, 1858, tome ii., p. 100.
4 See vol. ii., Digestion, p. 147, et seq.
FACIAL NERVE. 145
are animated by the motor root of the fifth. This nerve,
then, is not only the nerve of mastication, animating all of
the -muscles concerned in this act, except two of the most
unimportant depressors of the lower jaw (the genio-hyoid
and the platysma myoides), but it is concerned indirectly in
deglutition.
Facial Nerve, or Nerve of Expression (the Portio dura of
the Seventh).
The facial, the portio dura of the seventh according to
the arrangement of Willis, is one of the most interesting of
the cranial nerves. Its anatomical relations are quite intri-
cate, and its communications with other nerves, very numer-
ous. As far as can be determined by experiments upon
living animals, this nerve is exclusively motor at its origin ;
but in its course it presents anastomoses with the sympa-
thetic, with branches of the. fifth, and with the cervical
nerves, undoubtedly receiving sensory filaments. While
the chief physiological interest attached to this nerve de-
pends upon its action upon muscles, it is important to study
its origin, distribution, and communications.
Physiological Anatomy. — The portio dura of the seventh
has its apparent origin from the lateral portion of the me-
dulla oblongata, in the groove between the olivary and the
restiform body, just below the border of the pons Varolii, its
trunk being internal to the trunk of the portio mollis, or au-
ditory nerve. It is separated from the auditory by the two
filaments constituting what is known as the intermediary
nerve of Wrisberg, or the portio inter duram et mollem.
As this little nerve joins the facial, it must be included in
its root. It is called the accessory root by Sappey.1
There are certain pathological considerations which ren-
der the deep, or real origin of the facial a question of the
1 SAPPEY, Traite d'anatomie descriptive, Paris, 1852, tome ii., p. 251.
146 NERVOUS SYSTEM.
greatest interest and importance. In liemiplegia from in-
jury of the substance of the encephalon, particularly from
haemorrhage, there is almost always more or less paralysis
of the superficial muscles of the face. It has been observed
that in certain cases, the facial paralysis exists upon the
same side as the hemiplegia, the side opposite to the cere-
bral lesion, while in others, the palsy of the face is on the
same side as the lesion, the general hemiplegia being, as
usual, upon the opposite side. To explain these phenomena
theoretically, we must assume that in some cases, the brain-
lesion is to be located at a point where it involves the fila-
ments of origin of the facial, following them from without
inward, before they decussate, which would produce facial
paralysis on the same side as the lesion and none on the side
affected with general hemiplegia ; while in other cases, the
injury to the brain involves the roots of the facial after they
have decussated, when the paralysis of the face would be on
the same side as the paralysis of the rest of the body. It
would be interesting to see how far these pathological facts,
with their theoretical explanation, correspond with anatomi-
cal researches into the real origin of the nerves.
Many anatomists have endeavored to trace the fibres of
the facial from their point of emergence from the encepha-
lon to their true origin, but with results not entirely satis-
factory. At the present day, it is pretty generally agreed
that the fibres pass inward, with one or two deviations from
a straight course, to the floor of the fourth ventricle, where
they spread out and become fan-shaped. In the floor of the
fourth ventricle, certain of the fibres have been thought to
terminate in the cells of the gray substance, and others have
been traced to the median line, where they decussate ; the
course of most of the fibres, however, has never been satis-
factorily established.
It is evident, from physiological experiments, that the
decussation of the fibres in the floor of the fourth ventricle
itself is not very important. Yulpian has made, in dogs
FACIAL NERVE. 14:7
and rabbits, a longitudinal section in the middle line of the
ventricle, which would necessarily have divided the fibres
passing from one side to the other, without producing nota-
ble paralysis of the facial nerves upon either side.1 This
single fact is sufficient to show that the main decussation of
the fibres animating the muscles of the face takes place, if
at all, at some other point.
The following curious phenomenon, however, resulting
from this section, was noted by Yulpian : He found that
although there was no apparent paralysis of the orbicularis
muscle of the eye upon either side, the synchronism of the
movements of the two muscles seemed to be destroyed. It
is well known that in man, and in many of the lower ani-
mals, there is an involuntary action of these muscles simul-
taneously on the two sides in winking. After a longitudinal
section in the median line of the floor of the fourth ventri-
cle, the animals winked with either eye alternately, or with
one eye for a time without closing the other, but there was
no simultaneous action of the muscles on the two sides.2
The pathological facts bearing upon the question of de-
cussation of the filaments of origin of the facial have long
been recognized. They are, in brief, as follows : When
there is a lesion of the brain-substance anterior to the pons
Yarolii, the phenomena due to paralysis of the facial are
observed on the same side as the hemiplegia, opposite to the
side of injury to the brain. "When the lesion is either in the
pons or below it, the face is affected on the same side, and
not on the side of the hemiplegia. In view of these facts,
the remarkable phenomenon of hemiplegia upon one side
and facial paralysis upon the other is regarded as indi-
cating, with tolerable certainty, that the injury to the brain
has occurred upon the same side as the facial paralysis,
either in or posterior to the pons Yarolii. It is unnecessary
1 VULPIAK, Lemons sur la phy&iologie generate et comparee du systeme nervevx,
Paris, 1866, p. 480.
2 VCLPIAX, op. cit., p. 481.
148 NERVOUS SYSTEM.
to enter into a farther discussion of these facts, which are ac-
cepted by nearly all writers upon diseases of the nervous sys-
tem, and may be regarded as settled ; 1 and the only question
is, how far they can be explained by the anatomy of the parts.
As we have just seen, the fibres of origin of the facial
have been traced to the floor of the fourth ventricle, where
a few decussate, but the rest are lost. Ths question now is,
whether or not the fibres pass up through the pons, and de-
cussate above, as the pathological facts just noted would
seem to indicate. Anatomical researches upon this point
are entirely unsatisfactory ; and the existence of such a de-
cussation has never been clearly demonstrated. The patho-
logical observations, nevertheless, remain ; and, however in-
definite anatomical researches may have been, there can be
no doubt that lesions in one-half of the pons affect the facial
upon the same side, while lesions above have a crossed ac-
tion. The most that we can say upon this point is, that it
is a reasonable inference from pathological facts that the
nerves decussate anterior to the pons.
It will be only necessary to describe in a general way the
course of the fibres of distribution of the facial. The main
root of the facial, the auditory nerve, and the delicate inter-
mediary nerve of Wrisberg pass together into the internal
auditory rneatus. At the bottom of the meatus, the facial
and the nerve of Wrisberg enter the aqueeductus Fallopii,
following its course through the petrous portion of the tem-
poral bone. In the aqueduct, the nerve of "Wrisberg pre-
sents a little ganglioform enlargement, of a reddish color,
which has been shown to contain nerve-cells.2 The main
1 The reader is referred for a fuller consideration of these points to the re-
cent standard works upon practical medicine. The most complete collection of
cases of the so-called alternate paralysis was published by Gubler, in the Ga-
zette hebdomadaire de medecine et chirurgie, Paris, 1856, and in the volumes of
the same journal for 1858 and 1859. A characteristic case has lately been re-
ported by Prof. Hammond, in the Journal of Psychological Medicine, New York,
1871, vol. v., p. 14.
8 SAPPEY, Traite d1 'anatomic descriptive, Paris, 1862, tome ii., p. 254.
FACIAL NERVE. 149
root and the intermediary nerve then unite and form the
common trunk of the facial, which emerges from the cranial
cavity by the stylo-mastoid foramen.
In the aquseductus Fallopii, the facial gives off numerous
branches, as follows :
1. The large petrosal branch is given off from the gan-
glioform enlargement, and goes to MeckePs ganglion.
2. The small petrosal branch is given off at the ganglio-
form enlargement, or a very short distance beyond it, and
passes to the otic ganglion.
3. A small branch, the tympanic, is distributed to the
stapedius muscle.
4. The chorda tympani, a branch of great physiological
interest, passes through the cavity of the tympanum, and
joins the lingual branch of the inferior maxillary division
of the fifth as it passes between the two pterygoid muscles,
with which nerve it becomes closely united.
5. Opposite to the point of origin of the chorda tym-
pani, a communicating branch passes between the facial and
the pneumogastric, connecting these nerves by a double in-
osculation.
The five branches above described are given off in the
aquseductus Fallopii.1 The following branches are given off
after the nerve has emerged from the cranial cavity :
1. Just after the facial has passed out at the stylo-mastoid
foramen, it sends a small communicating branch to the
glosso-pharyngeal nerve. According to Sappey, this branch
is sometimes wanting.3
2. The posterior auricular nerve is given off by the facial
a little below the stylo-mastoid foramen. Its superior branch
is distributed to the retrahens aurem and the attollens aurem.
1 In the course of the facial in the aqueduct, two branches are sometimes
described, one going to the auditory, and another to the sympathetic filaments
accompanying the middle meningeal artery ; but their existence is denied by
many anatomists.
2 SAPPEY, Traite d'anatomie descriptive, Paris, 1852, tome ii., p. 259.
150 NERVOUS SYSTEM.
In its course, this nerve receives a communicating branch
of considerable size from the cervical plexus, by the auricu-
laris magnus. It sends some filaments to the integument.
The inferior, or occipital branch, the larger of the two, is
distributed to the occipital portion of the occipito-frontalis
muscle and to the integument.
3. The digastric branch is given off near the root of the
posterior auricular. It is distributed to the posterior belly
of the digastric muscle. In its course, it anastomoses with
filaments from the glosso-pharyngeal nerve. From the
plexus formed by this anastomosis, filaments are given off
to the digastric and to the stylo-hyoid muscle.
4. Near the stylo-mastoid foramen, a small branch is
given off, which is distributed exclusively to the stylo-hyoid
muscle.
5. Near the stylo-mastoid foramen, or sometimes a little
above it, a long and exceedingly delicate branch is given off,
which is not noticed in most works on anatomy. It is de-
scribed, however, by Hirschfeld, under the name of the lin-
gual branch.1 It passes behind the stylo-pharyngeal muscle,
and then by the sides of the pharynx to the base of the
tongue. In its course, it receives one or two branches from
the glosso-pharyngeal nerve, which are nearly as large as the
original branch from the facial. As it passes to the base of
the tongue, it anastomoses again by numerous filaments
with the glosso-pharyngeal. It then sends filaments of dis-
tribution to the mucous membrane, and finally passes to the
stylo-glossus and the palato-glossus muscle.
Having given off these branches, the trunk of the facial
passes through the parotid gland, dividing into its two great
terminal branches.
1. The temporo-facial branch, the larger, passes upward
and forward to be distributed to the superficial muscles of
the upper part of the face; viz., the attrahens aurem, the
1 LUDOVIC HIRSCHFELD, Traite et iconographie du systeme nerveux, Paris, 1866,
p. 206, and, Atlas, PI. xxx., Figs. 2, 13.
FACIAL NERVE. 151
frontal portion of the occipito-frontalis, the orbicnlaiis pal-
pebrarum, corrugator supercilii, pyraniidalis nasi, levator
labii superioris, levator labii superioris alseque nasi, the dila-
tors and compressors of the nose, part of the buccinator,
the levator anguli oris, and the zygomatic muscles. In its
course, it receives branches of communication from the au-
riculo-temporal branch of the inferior maxillary nerve. It
joins also with the temporal branch of the superior -maxil-
lary and with branches of the ophthalmic. In its course, it
thus becomes a mixed nerve, and is distributed in part to
integument.
2. The cervico-facial nerve passes downward and forward
to supply the buccinator, orbicularis oris, risorius, levator
labii inferioris, depressor labii inferioris, depressor anguli
oris, and platysma.
Summary of the Anastomoses and Distribution of the
Facial. — In the aquseductus Fallopii, filaments of communi-
cation go to Meckel's ganglion and the otic ganglion of the
sympathetic. The chorda tympani joins the lingual branch
of the inferior maxillary division of the fifth. A branch is
also sent to the pneumogastric. After the nerve has passed
out by the stylo-mastoid foramen, it sends a communicating
branch to the glosso-pharyngeal, and receives a branch from
the auricularis magnus. It anastomoses, also, outside of the
cranium, with the glosso-pharyngeal. In the course of the
nerve, it receives anastomosing filaments from the three
great divisions of the fifth.
It is thus seen that the facial, in its course, receives nu-
merous filaments from the great sensitive nerve of the face.
Certain of its fibres of distribution go to integument.
The muscles supplied by the facial are the stapedius, and
probably the tensor tympani, of the internal ear, the muscles
of the external ear, the occipito-frontalis, the posterior belly
of the digastric, the stylo-hyoid, the stylo-glossus, and the
palato-glossus. The two great branches of distribution, the
temporo-facial and the cervico-facial, are distributed to all of
152 NERVOUS SYSTEM.
the superficial muscles of the face, leaving the deep muscles,
or the muscles of mastication, to be supplied by the motor
root of the fifth. In addition, it supplies in part the platys-
ma myoides. "VYe have already seen that the buccal branch
of the small root of the fifth is not distributed to the
buccinator, but that this muscle is supplied exclusively by
branches from the facial.1
Properties and Function of the Facial Nerve. — It has
long been recognized that the facial is the motor nerve of
the superficial muscles of the face, and that its division pro-
duces paralysis of motion and no marked effects upon sensa-
tion. It is evident, also, from the numerous communica-
tions of the facial with the fifth, that it probably contains in
its course sensitive fibres. Indeed, all who have operated
upon this nerve have found that it is slightly sensitive after
it has emerged from the cranial cavity. It is a question,
however, of great importance to determine, whether or not
the facial be endowed with sensibility by virtue of its own
fibres of origin. The main root is evidently from the motor
tract, resembles the anterior roots of the spinal nerves, and
is distributed to muscles ; but this is joined by the interme-
diary nerve of "Wrisberg, which presents a small enlarge-
ment, undoubtedly containing nerve-cells, somewhat analo-
gous to the ganglia upon the posterior roots of the spinal
nerves.
If the facial possess any sensibility at its root, it is but
slight. In the early experiments of Sir Charles Bell, irrita-
tion of the facial exposed in an ass apparently produced no
pain,2 but the roots were not exposed in the cranial cavity.
Magendie, on the other hand, in repeating these observa-
tions, found the nerve distinctly sensitive.3 Longet, and
1 See page 142.
2 BELL, On the Nerves, etc. — Philosophical Transactions, London, 1821, Part
I., pp. 413, 418.
8 MAGENDIE, Journal de physiologic, Paris, 1822, tome ii., p. 67, note.
FACIAL NERVE. 153
most other experimenters, have also demonstrated the sen-
sibility of the nerve after it has passed out of the cranial
cavity,1 except the inferior branch, in which Magendie and
others have found no evidences of pain on irritating it in
living animals.2 Experiments have further shown that the
facial derives its sensibility in greatest part from the fifth
pair ; for section of the latter within the cranial cavity has
been found by Magendie to destroy the sensibility pf the
seventh.3 It is probable, however, from other experiments,
by Bernard, that the pain produced by section of the fifth
interfered with the experiment, and that a part of the sensi-
bility of the facial is derived from a communicating branch
from the pneumogastric. Bernard exposed the facial, with
this communicating branch, and found it sensitive ; but af-
ter division of the branch from the pneumogastric, which
produced considerable pain, the sensibility of the facial was
destroyed.4
Direct observations upon the properties of the facial as it
penetrates the auditory canal, and before it has received any
anastomosing branches from sensitive nerves, must be to a
certain extent unsatisfactory. All who have experimented
upon the nerves know that the pain and depression which
attend so serious an operation as that of exposing the roots
of a nerve in the cranial cavity are sufficient to render it
doubtful whether the parts be in a condition to exhibit a
slight degree of sensibility, which the nerves may possess
when perfectly normal. Magendie B and Bernard," who have
exposed the roots of origin of the facial, state unreservedly
that they are absolutely insensible ; but Longet very justly
1 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 567.
2 MAGENDIE, Lefons sur les fonctions et les maladies du systeme nerveux, Paris,
1841, tome ii., p. 181.
3 MAGENDIE, op. tit., p. 222.
4 BERNARD, Lemons sur la physiologic et la pathologic du systeme nerveux, Paris,
1858, tome ii., p. 28.
6 MAGENDIE, Systeme nerveux, Paris, 1841, tome ii., p. 208.
6 BERNARD, Systeme nerveux, Paris, 1858, tome ii., p. 28.
154 NERVOUS SYSTEM.
remarks that the conditions under which such observations
are made have not been, in his hands, sufficiently favor-
able to admit of a rigorous conclusion on this point.1 The
testimony of direct experimentation is in favor of the in-
sensibility of the* facial at its origin. It is true that the
intermediary nerve of "Wrisberg has a certain anatomical
resemblance to the sensitive nerves, chiefly by virtue of its
ganglioform enlargement ; but direct experiments are want-
ing to show that it is actually sensitive. In view of this
fact, it is impossible to reason conclusively from its anatomi-
cal characters alone.
The most convenient way to consider the functions of
the facial will be to take up seriatim the properties and dis-
tribution of its different branches.
Functions of the Branches of the Facial within the Aque-
duct of Fallopius. — The first branch, the large petrosal, is
the motor root of Meckel's ganglion. This will be referred
to again in connection. with the sympathetic system. The
second branch, the small petrosal, is one of the motor roots
of the otic ganglion of the sympathetic. It is thought by
Longet that this branch simply passes through the ganglion
to be distributed to the tensor tympani muscle. This au-
thor regards the small petrosal and the tympanic branch of
the facial as branches exclusively furnished by the interme-
diary nerve of Wrisberg, which he considers as the nerve of
the tympanum, and has called the " tympanic motor nerve."
This, however, is advanced as a mere supposition, not en-
tirely proven by experiments.11 The third branch, the tym-
panic, is distributed exclusively to the stapedius muscle.
The second and third branches will be again considered in
connection with the physiology of the internal ear.
According to the experiments of Savart,3 paralysis of the
1 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 567.
2 Ibid., p. 579.
8 SAVART, Recherches sur les usages de la membrane du lympan et de Voreille
externe. — Journal de physiologic, Paris, 1824, tome iv., p. 204.
FUNCTIONS OF THE CHOKDA TYMPANI. 155
tensor tympani sliould produce an increased susceptibility
of the ear to ordinaiy sonorous vibrations. Contrary to
what might be supposed, it is pretty certain that the mem-
brane of the tympanum vibrates most intensely when it is
relaxed, the vibration being much less when it is rendered
tense by the action of the large muscle of the malleus. This
view is accepted by Muller, who repeated and extended the
experiments of Savart. Muller states that this is a physical
law with regard to membranes of the extent of the tympa-
num.1 It is farther carried out by certain cases of paralysis
of the facial in the human subject, which present, among
other symptoms, a painful sensibility of the ear to powerful
impressions of sound. One of the earliest observed and
most remarkable of these is the case of Prof. Roux, of
Paris, who suffered from a temporary facial paralysis, and
who noted that " the membrane of the tympanum was pain-
fully sensible even to slight noises." a This symptom has
often been noted in facial palsy.3
The fourth branch, the chorda tympani, is so important
that it demands special consideration. The fifth branch is
given off opposite to the origin of the chorda tympani and
passes to the pneumogastric, to which nerve it probably sup-
plies motor filaments. We have already seen, in studying
the properties of the roots of the facial, that in this branch,
sensory filaments pass from the pneumogastric and consti-
tute a part of the sensory connections of the facial.4
Functions of the Chorda Tympani. — This branch passes
between the bones of the ear and through the tympanic cav-
ity to the lingual branch of the inferior maxillary division
of the fifth, which it joins at an acute angle, between the
pterygoid muscles. It has been a question whether this
1 MI-LLER, Elements of Physiology, London, 1843, vol. ii., p. 1256.
8 BELL, The Nervous System, London, 1844, p. 329.
3 BERNARD, Lerons sur la physiologic et la pathologic du systeme ncrvevx, Paris,
1858, tome ii., p. 114.
4 See page 153.
156 NEKVOUS SYSTEM.
nerve be simply enclosed in the sheath of the lingual branch
of the fifth or be so closely connected with it that it cannot
be traced to a distinct distribution. Upon this point we are
disposed to adopt the opinion of Sappey, who, as the result
of minute dissections, regards the union as complete, " fibril
to fibril." As regards the portion of the facial which fur-
nishes the filaments of the chorda tympani, it is impossible
to determine anatomically whether these come from the
main root or from the intermediary nerve of Wrisberg, as
the fibres of these roots are closely united before the chorda
tympani is given off.1
Concerning the general properties of the chorda tym-
pani, it is curious to note the opposite opinions of different
physiologists ; some regarding it as a motor nerve, others
as purely sensitive, and others as a special nerve of taste.
When we come to analyze the actual experimental observa-
tions upon the nerve, it is seen that it cannot be regarded
as an ordinary motor nerve ; for galvanization of the root
of the facial before this branch is given off, and careful gal-
vanization of the chorda tympani itself, produce not the
slightest movement in the tongue.2 The operative proced-
ure necessary to expose the parts is so severe as to render
observations with regard to its sensibility very unsatisfac-
tory. It is certain, however, that it is not an acutely sen-
sitive nerve like the fifth, or like certain branches of the
pneumogastric.
The only questions that we propose fo consider in this
connection relate to the functions of the chorda tympani as
a nerve of gustation, and as it influences the secretion of the
submaxillary gland.
There can be no doubt with regard to the influence of
the chorda tympani upon the sense of taste in the anterior
portion of the tongue. "Without citing all of the experi-
ments and pathological observations bearing upon this ques-
1 SAPPEY, Traite d'anatomie, Paris, 1852, tome ii., p. 258.
2 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 581, note.
FUNCTIONS OF THE CHORDA TYMPANI. 157
tion, it is sufficient to state, that in cases of disease or injury,
in which the root of the facial is involved so that the chorda
tympani is paralyzed, in addition to the ordinary phenom-
ena of paralysis of the superficial muscles of the face, there
is loss of taste in the anterior portion of the tongue on the
side corresponding to the lesion. Numerous cases of this
kind are quoted in works on physiology, which will be re-
ferred to more fully in connection with the subject of gus-
tation.
In 1863, we had under observation, for several months,
a soldier who received a gunshot-wound, the ball passing
through the head, entering just above the ala of the nose
on the left side and emerging behind the mastoid process
of the right temporal bone. The wound was nearly healed
while he was under observation, and the usual symptoms of
complete facial paralysis were manifested on the right side.
The buccinator and the orbicularis oculi were completely
paralyzed. Vision in the right eye was slightly impaired,
but was improving. The hearing was perfect, and there
were no abnormal phenomena except those apparently due
to injury of the facial. The sense of taste was entirely abol-
ished in the anterior portion of the tongue on the right side.
Experiments on this point were repeatedly made with salt,
pepper, and other sapid substances. This patient was ex-
amined on one occasion by Prof. Dalton, and was exhibited
in two successive years to the class at the Bellevue Hospi-
tal Medical College, when the above-mentioned facts were
verified.
Physiologists have observed loss of taste in the anterior
portion of the tongue, in dogs, cats, and other animals, fol-
lowing section of the root of the facial or of the chorda tym-
pani. Some observers, it is true, have failed to note the
phenomena satisfactorily, and there is some difference of
opinion with regard to the real origin of the gustatory fila-
ments ; but the fact that the chorda tympani influences the
taste can hardly be doubted. Adopting this view, w^e shall
158 NEKVOUS SYSTEM.
defer the full consideration of the functions of the chorda
tympani until we come to treat of the special sense of
taste.
Schiff, in 1851, was the first to note the influence of the
chorda tympani upon the secretion of the submaxillary
gland. In some works on physiology, the experiments of
Ludwig are referred to as the first upon this subject ; 1 but
Ludwig only noted the influence upon the salivary secre-
tion, of filaments going to the submaxillary from the lingual
branch of the fifth, without experimentally demonstrating
their real origin.2 In the experiments of Schiff, the chorda
tympani was exposed and the flow of the submaxillary saliva
noted. Upon division of the chorda tympani, the flow of
saliva was momentarily increased, but was soon arrested ;
and subsequently, stimulation of the gustatory sense failed
to induce secretion, as it does when the nerve is intact.3
Similar experiments, on a much more extended scale, were
made by Bernard, in the following way :
The duct of the submaxillary gland was exposed in a
dog, and into it was fixed a silver canula. The nervous
filaments going to the gland from the lingual branch of the
fifth were then isolated. A little vinegar introduced into
the mouth caused an abundant flow of saliva from the tube.
The chorda tympani was then divided, by introducing a
sharp instrument through the membrane into the tympanic
cavity. After division of the nerve, the introduction of
vinegar into the mouth failed to excite the salivary secre-
tion. From this and similar experiments, Bernard con-
cludes that the chorda tympani is the motor nerve of the
submaxillary gland. After having arrested the secretion by
section of the chorda tympani, the action of the gland was
1 LONGET, Traite de physiologie, Paris, 1869, tome iii., p. 582.
8 LUDWIG, Neue Versuche iiber die JBeihilfe der Nerven zur SpelfJidabzon-
derung. — Zdtschrift fur rationette Medicin, Heidelberg, 1851, Neue Folge, Bd. i.,
S. 255, et seq.
3 SCHIFF, Lemons sur la physiologie de la digestion, Florence et Turin, 1867,
tome i., p. 217.
MOVEMENTS OF THE PALATE AND TJTTTLA. 159
induced by galvanization of the peripheral end of the nerve.1
Section of the facial after its passage out of the stylo-mastoid
foramen did not arrest the action of the parotid ; but section
of the nerve within the cranium arrested the secretion, both
of the parotid and submaxillary.9
These observations show conclusively that the facial,
either through branches from its proper roots or its fila-
ments of communication with other nerves, regulates the
secretion of at least two of the salivary glands ; a fact to
which we have already alluded in another volume.3
Influence of Various Branches of the Facial upon the
Movements of the Palate and Uvula. — There can be little
doubt that filaments from the facial animate certain of the
movements of the velum palati and uvula. It has been ob-
served that, in certain cases of facial paralysis, the palate
upon one side is perfectly flaccid and the uvula is drawn to
the opposite side. Montault * cites a case of this kind, and
a very striking example is given in full by Bernard ; 6 but
these phenomena do not occur unless the nerve be affected
at its root or within the aquseductus Fallopii. It is true
that the uvula is frequently drawn to one -side or the other
in persons unaffected with facial paralysis, as was observed
by Debrou,6 but it is none the less certain that it is deviated
as a consequence of paralysis of the facial in some instances.'
These facts, however, in the absence of direct experiments,
do not show conclusively that the facial supplies the muscles
of the seft palate.
1 BERNARD, Lemons sur la physiologic el la pathologic du systcme nerveux, Paris,
1858, tome ii., p. 148, et seq.
8 Op. tit., p. 155.
3 See vol. in., Secretion, p. 31.
4 MOXTAULT, Dissertation sur Themiplegiefacialc, These, No. 300, Paris, 1831.
5 BERNARD, Lecons sur la physiologic et la patJiologie du systeme nerveux, Paris,
1858, tome ii., p. 133.
6 DEBROU, Theses dc lecole de medecine, Paris, 1841, No. 266.
* LOXGET, Traite de physiologic, Paris, 1869, tome iii., p. 576.
Ill
160 NERVOUS SYSTEM.
Direct experiments upon the roots of the facial have not
been followed by uniform results. Debrou, in the thesis
just referred to, mentions one experiment in which galvani-
zation of the facial within the cranial cavity produced de-
cided contraction of the muscles of the palate ; but in four
others, the results were negative. Nuhn, however, pro-
duced contractions of these muscles by galvanization of the
nerve in the cranium in a man immediately after decapita-
tion.1 The experiments of Bernard upon this point are the
most conclusive ; but while they show, beyond a doubt, that
the facial animates the movements of the soft palate, they
do not indicate the course of the filaments from the nerve
to the muscles. In these experiments, made in connection
with M. Davaine, the whole of the velum palati was exposed
in a large-sized dog, by cutting through the hyoid bone. The
trunk of the glosso-pharyngeal nerve was then exposed in
the neck, near its point of emergence at the posterior fora-
men lacerum, and the animal was killed by section of the
spinal cord just below the origin of the cranial nerves. This
being done, the glosso-pharyngeal was galvanized, which pro-
duced violent contractions of the velum, the pillars of the
fauces, and a part of the pharynx, on one side. The nerve
was then divided, and the galvanization applied to its pe-
ripheral end without producing any movement in the velum.
The central end was then galvanized, when the contractions
were as vigorous as when the nerve was intact. This result
would lead to the supposition that contractions of the mus-
cles of the palate following galvanization of the glosso-
pharyngeal are reflex and not due to the direct action of
filaments of distribution from this nerve. In a second ex-
periment, the parts were exposed in the same way, and, in
addition, the facial was divided upon the right side at its en-
trance into the internal auditory canal. The glosso-pharyn-
1 NUHN, Versuche an einem Eiilhaupteten nebst erlduternden Versuchen an
Thieren. — Zeitschrift fur rationelle Medicin, Heidelberg, 1853, Neue Folge, Bd.
fii., S. 129, et seq.
MOVEMENTS OF THE PALATE AND UVULA. 161
geal nerve was then galvanized upon the side on which the
fhcial had been divided, with the effect of producing move-
ments of the pillars of the fauces, but not of the velum palati
itself. The glosso-pharyngeal was then galvanized upon the
side on which the facial was intact, which produced move-
ments of the velum the same as in the first experiment.
Galvanization of the pneumogastric, the sublingual, and the
lingual branch of the fifth, failed to produce movements of
the velum.
" The first experiment proves that the glosso-pharyngeal
nerve is not the motor nerve of the velum palati, but that it
induces reflex movements by the excitation which it trans-
mits to the nervous centre, an excitation which is carried to
the parts by another nerve.
"The second experiment proves that the reflex move-
ments of the velum palati, induced by the excitation of the
glosso-pharyngeal,- are in part transmitted by the facial
nerve, the movements of the pillars not being produced by
filaments belonging to this nerve." J
Bernard also noted a fact, which has sometimes been
observed in cases of facial paralysis, that the point of the
tongue is deviated after section of the facial ; which is ex-
plained by the presence of a filament described by Hirsch-
feld, going from the facial to the tongue.
As we before remarked, the experiments of Bernard do
not indicate the mode of communication between the facial
and the muscles of the palate. Longet regards the filaments
of the facial which influence the levator palati and azygos
uvulse muscles as derived from the large petrosal branch
of the nerve, passing to the muscles through MeckeFs gan-
glion, the filaments to the palato-glossus and the palato-
pharyngeus being given off from the glosso-pharyngeal, but
originally coming from an anastomosing branch of the facial.
As regards the branches of communication from the glosso-
1 BERNARD, Lemons sur la pkysiologie et la pathologic du systeme nerveux, Paris,
1858, tome ii., p. 178.
i(>2 NERVOUS SYSTEM.
pharyngeal, Longet mentions a preparation by Richet, in
the museum of the tiooU de medecine, of Paris, in which
branches of the facial on one side passed directly to the
palato-glossus and the palato-pharyngeus without any con-
nection with the glosso-pharyngeal nerve.1 In our ana-
tomical description of the branches of the facial, we have
already noted a filament, described by Hirschfeld, which
passes to the stylo-glossus and palato-glossus muscles.2
This is the filament affected in deviation of the point of the
tongue.
In view of the pathological examples of paralysis of the
palate and uvula in certain cases of facial palsy, the frequent
occurrence of contractions of the muscles of these parts upon
galvanization of the facial, and the reflex action through the
glosso-pharyngeal and the facial, there can be little doubt
that the muscles of the palate and uvula are animated by
filaments derived from the seventh nerve. The effects of
paralysis of these muscles are manifested by more or less
difficulty in deglutition and in the pronunciation of certain
words, with great difficulty in the expulsion of mucus collect-
ed in the back part of the mouth and the pharynx. These
points are well illustrated in the case of facial palsy, with
paralysis of one side of the palate, cited by Bernard.3
Functions of the External Branches of the Facial. — The
general function of the branches of the facial going to the
superficial muscles of the face is sufficiently evident, in view
of our present knowledge of the distribution of these branch-
es and the general properties of the nerve. Throughout the
writings of Sir Charles Bell, the facial is spoken of as the
" respiratory nerve of the face." It is now recognized as the
nerve which presides over the movements of the superficial
muscles of the face, not including those directly concerned
in the act of mastication. This being its general function, it
1 LONGET, op. tit., tome ill, p. 581. 2 See page 150.
3 BERNARD, op. tit., tome ii., p. 133.
EXTERNAL BRANCHES OF THE FACIAL. 163
is easy to assign to each of what may be termed the external
branches of the facial its particular office.
Just after the nerve has passed out at the stylo-mastoid
foramen, it sends to the glosso-pharyngeal the communicat-
ing branch, the functions of which we have just considered
in connection with the movements of the palate.
The posterior auricular branch, becoming sensitive by
the addition of filaments from the cervical plexus, gives sen-
sibility to the integument on the back part of the ear and
over the occipital portion of the occipito-frontalis muscle.
It animates (the retrahens and the attollens aurem, muscles
but little developed in man, but very important in certain
of the inferior animals. It also animates the posterior por-
tion of the occipito-frontalis muscle.
The branches distributed to the posterior belly of the
digastric and to the stylo-hyoid muscle simply animate these
muscles, one of the uses of which is to assist in deglutition.
The same may be said of the filaments that go to the stylo-
glossus.
The two great branches distributed upon the face after
the trunk of the nerve has passed through the parotid gland
have the most prominent function. Both of these branches
are somewhat sensitive from their connections with other
nerves, and are distributed in small part to integument.
The temporo-facial branch animates all of the muscles of
the upper part of the face. In complete paralysis of this
branch, the eye is constantly open, even during sleep, from
paralysis of the orbicularis muscle. In cases of long stand-
ing, the globe of the eye may become inflamed from con-
stant exposure, from abolition of the movements of winking
by which the tears are distributed over its surface and little
foreign particles are removed, and, in short, from absence
of the protective action of the lids. In these cases, the lower
lid may become slightly everted. The frontal portion of the
occipito-frontalis, the attrahens aurem, and the corrugator
supercilii muscles, are also paralyzed. The most prominent
164 NERVOUS SYSTEM.
symptom of paralysis of these muscles is inability to corru-
gate the brow upon one side, as in frowning.
Paralysis of the muscles that dilate the nostrils has been
shown to have an important influence upon respiration
through the nose. It was the synchronism between the
acts of dilatation of the nostrils and the movements of in-
spiration which first led Sir Charles Bell to regard the facial
as a respiratory nerve. In instances of complete paralysis
of the nostril of one side, there is frequently some difficulty
in inspiration. Sir Charles Bell refers to a case in which,
when " the patient lay with the sound side against the pil-
low, he was under the necessity of holding the paralytic
nostril open with the fingers, in order to breathe freely."
In the horse, the movements of the nostrils are essential to
respiration, the animal being unable to breathe through the
mouth. When both facial nerves are divided in this animal,
the nostrils collapse and are occluded with each effort at in-
spiration, and death takes place from suffocation.3
Sir Charles Bell 3 and others have also noted the inter-
ference with olfaction, due to the inability to inhale with
one nostril, in cases of facial paralysis. The influence of
the nerve in the act of conveying odorous emanations to
the olfactory membrane is sufficiently evident after what
we have remarked concerning the action of the facial in
respiration.
The effects of paralysis of the other superficial muscles
of the face are manifested in the distortion of the features,
from the unopposed action of the muscles upon the sound
side ; a phenomenon which is sufficiently familiar to the prac-
1 BELL, The Nervous System of the Human Body, London, 1844, p. 54. The
case referred to is No. VI., in the Appendix ; but this seems to be an error, as
no such circumstance is mentioned in this case. Still the fact illustrated is not
to be doubted.
2 BERNARD, Lemons sur la physiologie et la pathologic du systeme nerveux, Paris,
1858, tome ii., p. 38.
3 BELL, Of Smelling as influenced by the Portio Dura of the Seventh Ntrve.—*
The Nervous System, London, 1844, p. 134.
EXTERNAL BRANCHES OF THE FACIAL. 165
tical physician. When facial palsy affects one side and is
complete, the angle of the rnouth is drawn to the opposite
side, the eye upon the affected side is widely and perma-
nently opened, even during sleep, and the face has upon
that side a peculiarly expressionless appearance. When a
patient affected in this way smiles or attempts to grimace,
the distortion is much increased. The lips are paralyzed
upon one side, which sometimes causes a flow of saliva- from
the corner of the mouth. In the lower animals that use
the lips in prehension, paralysis of these parts interferes
considerably with the taking of food. The flaccidity of the
paralyzed lips and cheek in the human subject sometimes
causes a puffing movement with each act of expiration, as if
the patient were smoking a pipe.
We have already seen that the buccinator is not supplied
by filaments from the nerve of mastication, but is animated
solely by the facial. Paralysis of this muscle interferes ma-
terially with mastication, from a tendency to accumulation
of the food between the teeth and the cheek. Patients
complain of this difficulty, and sometimes keep the food
between the teeth by pressure with the hand. In the rare
instances in which both facial nerves are paralyzed, there is
very great difficulty in mastication from the cause just men-
tioned.
The functions of the external branches of the facial are
thus sufficiently simple ; and it is only as its deep branches
affect the taste, the movements of deglutition, etc., that it is
difficult to ascertain their exact office. As this is the nerve
of expression of the face, it is in the human subject that
the phenomena attending its paralysis are most prominent.
"When both sides are affected, the appearance is most re-
markable, the face being absolutely expressionless and look-
ing as if it had been covered with a mask.
CHAPTER YI.
SPINAL ACCESSORY AND SUBLINGTJAL NERVES.
Spinal accessory nerve (third division of the eighth)— Physiological anatomy-
Properties and functions of the spinal accessory — Functions of the internal
branch from the spinal accessory to the pneumogastric — Influence of the
spinal accessory over the vocal movements of the larynx — Influence of the
internal branch of the spinal accessory upon deglutition — Influence of the
spinal accessory upon the heart — Functions of the external, or muscular
branch of the spinal accessory — Sublingual, or hypoglossal nerve (ninth) —
Physiological anatomy — Properties and functions of the sublingual — Glos-
so-labial paralysis.
A DESCRIPTION of the properties and functions of the spi-
nal accessory and the sublingual completes the physiological
history of the motor nerves emerging from the cranial cav-
ity. The functions of these nerves are important, and, in
the case of the spinal accessory, possess considerable inter-
est, from the fact that physiological investigations have, only
within a few years, determined the significance of certain of
its anatomical relations. As we have done in studying the
other motor nerves, we will treat successively of their ana-
tomical relations, general properties and functions.
Spinal Accessory Nerve. (Third Division of the Eighth.)
— The spinal accessory nerve, from the remarkable extent
of its origin, its important anastomoses with other nerves,
and its curious course and distribution, has long engaged
the attention of anatomists and physiologists, who have ad-
vanced many theories with regard to its office. We will
content ourselves, however, with a simple description of its
SPINAL ACCESSORY. 167
anatomy as it appears from late researches, and will begin
its physiological history with the comparatively recent ex-
periments which have advanced our positive knowledge of
its properties.
Physiological Anatomy. — The origin of this nerve is
very extensive. A certain portion arises from the lower
half of the medulla oblongata, and the rest takes its- origin
below, from the upper two-thirds of the cervical portion of
the spinal cord. That portion of the root which arises from
the medulla oblongata is called, by the French, the bulbar
portion, the roots from the cord constituting the spinal por-
tion. Inasmuch as there is a marked difference between the
functions of these two portions, the anatomical distinction
just mentioned is important.
The superior roots arise by four or five filaments from
the lower half of the medulla oblongata below the origin
of the pneumogastrics. These filaments of origin, in prep-
arations hardened by prolonged immersion in alcohol, are
shown to be connected with the lateral portion of the me-
dulla, and not with the posterior columns. Their origin
seems, therefore, to be from the motor tract.1
The spinal portion of the nerve arises from the upper
part of the cervical division of the spinal cord, between the
anterior and posterior roots of the upper four or five cervi-
cal nerves. The filaments of origin are from six to eight in
number. The most inferior of these is generally single, the
other filaments being frequently arranged in pairs. These
take their origin from the lateral portion of the cord, rather
nearer the posterior median line than the roots from the
medulla oblongata.
Following the nerve from its most inferior filament of
origin upward, it gradually increases in size by union with
its other roots, enters the cranial cavity by the foramen
magnum, and passes to the jugular foramen, by which it
1 SAPPEY, Traite tfanatomie descriptive, Paris, 1852, tome ii., p. 298.
168 NERVOUS SYSTEM.
emerges, in connection with the glosso-phar yngeal, the pneu-
mogastric, and the internal jugular vein.
In its course, the spinal accessory anastomoses with sev-
eral nerves. Just as it enters the cranial cavity, it receives
filaments of communication from the posterior roots of the
upper two cervical nerves. These filaments, however, are
not constant. It frequently, though not constantly, sends a
few filaments to the superior ganglion, or ganglion of the
root of the pneumogastric. After it has emerged by the
jugular foramen, it sends a branch of considerable size to
the pneumogastric, from which nerve it also receives a few
filaments of communication. This branch will be again re-
ferred to in connection with the distribution of the nerve.
In its course, it also receives filaments of communication
from the anterior branches of the second, third, and fourth
cervical nerves.
In its distribution, the spinal accessory presents two
branches. The first, or anastomotic branch, passes to the
pneumogastric just below the plexiform enlargement which
is sometimes called the ganglion of the trunk of the pneu-
mogastric.
The internal, or anastomotic branch, is composed princi-
pally, if not entirely, of the filaments that take their origin
from the medulla oblongata. As it joins the pneumogastric,
it subdivides into two smaller branches. The first of these
forms a portion of the pharyngeal branch of the pneumo-
gastric. The second becomes intimately united with the
pneumogastric, lying at its posterior portion, and furnishes
filaments to the inferior, or recurrent laryngeal branch,
which is distributed to all of the muscles of the larynx ex-
cept the crico-thyroid. The passage of the filaments 'from
the spinal accessory to the pharyngeal branch of the pneu-
mogastric is easily observed ; but the fact that filaments
from this nerve pass to the larynx by the recurrent laryn-
geal has been ascertained only by physiological experiments.
The external, or large branch of the spinal accessory,
SPINAL ACCESSORY. 169
called the muscular branch, penetrates and passes through
the posterior portion of the upper third of the sterno-cleido-
mastoid muscle, goes to the anterior surface of the trape-
zius, which muscle receives its ultimate branches of distri-
bution. In its passage through the sterno-cleido-mastoid,
it joins with branches from the second and third cervical
nerves, and sends filaments of distribution to the muscle.
Although the two muscles just mentioned receive numerous
motor filaments from the spinal accessory, they are also sup-
plied from the cervical nerves ; and, consequently, they are
not entirely paralyzed when the spinal accessory is divided.
Properties and Functions of the Spinal Accessory. — Not-
withstanding the great difficulty in exposing and operating
upon the roots of the spinal accessory, it has been demon-
strated that their galvanization produces convulsive move-
ments in certain muscles. The most satisfactory experi-
ments with relation to the general properties of the roots
were made by Bernard. This physiologist cut through
the occipito-atloid membranes and galvanized the filaments
within the spinal canal. By galvanizing the filaments aris-
ing from the medulla oblongata, he produced contractions
of the muscles of the pharynx and larynx and no move-
ments of the sterno-mastoid and trapezius. Galvanization
of the roots arising from the spinal cord produced move-
ments of the two muscles just mentioned, and absolutely
no movements in the larynx.1 Bernard has further shown
that the roots of the nerve are endowed with recurrent
sensibility from the posterior roots of the first three pairs
of cervical nerves.2 In view of these experiments, it is evi-
dent that the true filaments of origin of the spinal accessory
are motor ; and it is further evident that the filaments from
J BERNARD, Recherche* experimentales sur leg fonctions du nerf spinal, p. 731.
It is stated in a note that this memoir was printed in the Archives de medecine^
in 1844.
s Loc. cit., p. 730. "We have already fully considered the subject of recur-
rent sensibility in the anterior roots of the spinal nerves (see page 81).
1TO NERVOUS SYSTEM.
the medulla oblongata are distributed to the muscles of the
pharynx and larynx, while the filaments from the spinal cord
go to the sterno-cleido-mastoid and trapezius.
The trunk of the spinal accessory, after the nerve has
passed out of the cranial cavity, is endowed with a certain
degree of sensibility. If the nerve be divided, the periph-
eral extremity manifests the recurrent sensibility, but the
central end is also sensible, probably from direct filaments
of communication from the cervical nerves and the pneumo-
gastric. As we have remarked, however, in treating of the
properties of some other of the cranial nerves, it is exceed-
ingly difficult to note satisfactorily a slight degree of sensi-
bility in nerves that can be exposed only by a tedious and
painful operation.
The functions of the external, or muscular branch of the
spinal accessory are sufficiently evident ; and the effects of
the destruction of the nerves on both sides, as far as this
branch is concerned, simply resolve themselves into the
phenomena due to partial paralysis of the sterno-mastoid
and trapezius ; but the functions of the branch which joins
the pneumogastric are much more complex. Without dis-
cussing the speculative views of the older anatomists and
physiologists, we will commence with the experiments of
Bischoff, which were the first to give us any definite ideas
of the functions of the internal branch.
Functions of the Internal Branch from the Spinal Acces-
sory to the Pneumogastric. — Bischoff attempted to ascertain
the functions of this branch by dividing the roots of the
spinal accessory on both sides in a living animal. The re-
sults of his experiments may be stated in a very few words.
He attempted to divide all of the roots of the nerves on
both sides by dissecting down to the occipito-atloid space
and penetrating into the cavity of the spinal canal. In the
first three experiments on dogs, the animals died so soon
after section of the nerves, that no satisfactory results were
IXTERXAL BRANCH OF THE SPINAL ACCESSORY. 171
obtained. In two succeeding experiments on dogs, the ani-
mals recovered. After division of the nerves, the voice
became hoarse ; but a few weeks later, became normal. On
killing the animals, an examination of the parts showed that
some of the filaments of origin had not been divided. An
experiment was then made upon a goat, but this was unsat-
isfactory, as the roots were not completely divided. Finally,
another experiment was made upon a goat. In this, the
results were most satisfactory. After division of the nerve
upon one side, the voice became hoarse. As the filaments
were divided upon the opposite side, the voice was enfeebled,
until finally it became extinct. The sound emitted after-
ward was one which could in nowise be called voice, "qui
neutlqi.iam vox appellari potuit"1 This experiment was
made in the presence of Tiedemann and Seubertus, and was
not repeated.
It is evident to any one familiar with the elaborate re-
searches of Bernard upon the spinal accessory, that it was
only necessary to confirm the single successful experiment
of BischofF to settle the fact of the influence of this nerve
upon phonation. The great difficulty of the operative pro-
cedure, however, prevented its repetition on an extended
scale. Longet, in 1841,* published an account of some ex-
periments confirming, to a certain extent, those of Bischoif;
but in his treatise on the nervous system, published in 1842,*
he does not seem to regard the spinal accessory as the exclu-
sive nerve of phonation, as he does in his work on physi-
ology, published after the experiments of Bernard.4 The
results of the experiments performed at this time by Longet
1 BISCHOFF, Nervi Accessorii Willisii Anatomia et Physiologia, Darmstadii,
1832, p. 94.
s LOXGET, Recherches experimentalts sur les fonctions des nerfs, dcs muscles du
larnyx et sur F influence du nerf accessoire de Willis dan* la phonation. — Gazette
mcdicale, Paris, 1841, 2eme serie, tome ix., p. 472.
3 LOXGET, Anatomic et physiologic du systeme nerveux, Paris, 1842, tome ii.,
p. 263.
4 LOXGET, Trait* de pfiysiologie, Paris, 1869, tome iii., p. 516.
172 NERVOUS SYSTEM.
were by no means so satisfactory as tlie single successful ob-
servation of Bisclioif. In his memoir on the spinal acces-
sory, Bernard gives full credit to Bischoff, and quotes from
this author the very words we have just cited. "With regard
to the question of priority in the description of the function
of this nerve in phonation, there can be no doubt concern-
ing the accuracy of the experiment of Bischoff and its correct
interpretation, in 1832. He demonstrated that the nerve
presiding over the voice is the spinal accessory ; although
the fact rested on a single successful experiment, and was
not accepted by physiologists before it had been fully con-
firmed by the repeated and conclusive experiments of Ber-
nard, made by an entirely different method. To Bernard,
however, remains, as we shall presently see, the merit of
having demonstrated that the vocal muscles are supplied
by those filaments of the spinal accessory that take their
origin from the medulla oblongata.
Bernard, whose ingenious experiments determined ex-
actly the influence of the spinal accessory over the vocal
movements of the larynx, first repeated the experiments
of Bischoff; but the animals operated upon died so soon,
from hsemorrhage, or other causes, that his observations
were not satisfactory.1 After many unsuccessful trials, he
succeeded in overcoming all difficulties, by following the
trunk of the nerve back to the jugular foramen, seizing
it here with a strong pair of forceps, and drawing it out
by the roots.2 This operation is difficult, but we have sev-
1 BERNARD, Recherches experimentales sur lesfonctions du nerf spinal, p. 733.
Bernard considers that death is due after this operation, as performed by Bis-
choff, to the passage of air into the veins.
8 The operative procedure employed by Bernard is the following: The
trunk of the nerve is exposed as it passes through the sterno-cleido-mastoid
muscle. It is then followed up by careful dissection, avoiding blood-vessels as
much as possible, to the posterior foramen lacerum, when the sublingual is seen
crossing the course of the pneumogastric. It is here that the anastomotic
branch leaves the spinal accessory to go to the pneumogastric. At this point,
the external branch, with the anastomosing branch, is seized with a pair of
rather broad-billed forceps, and gentle but firm traction is applied to the entire
INTERNAL BRANCH OF THE SPINAi ACCESSORY. 173
eral times performed it with entire success, and verified, in
every regard, the facts observed by Bernard. Within the
last year, the excellent assistant to the chair of Physiology
at the Bellevue Hospital Medical College, Dr. C. F. Koberts,
has succeeded in extirpating these nerves for class-demonstra-
tions. The operation is generally most successful in cats,
though Bernard has succeeded frequently in other animals.
When one spinal accessory is extirpated, the vocal sounds
are hoarse and unnatural. When both nerves are torn out,
in addition to the disturbance of deglutition and the partial
paralysis of the sterno-mastoid and trapezius muscles, the
voice becomes extinct. Animals operated upon in this way
move the jaws and make evident efforts to cry, but no vocal
sound is emitted. This condition is very striking ; and in-
asmuch as Bernard has kept animals, with both nerves ex-
tirpated, for months, the question of the function of these
nerves in phonation may now be regarded as definitively
settled.
It remains now to consider the experimental facts with
regard to the influence of the different filaments of origin
of the spinal accessory on the voice. These are simple, and
entirely conclusive ; and they are due exclusively to the re-
searches of Bernard. This experimenter found that division
of the roots of origin from the spinal cord not only did not
affect the voice, but sometimes seemed to render it clearer ;
but that division of the roots of origin from the medulla ob-
longata abolished the voice, though the inferior roots were
intact.1
It is not necessary to discuss the action of the muscles
of the larnyx in phonation, as this subject has already been
considered in full in another volume.3 The beautiful experi-
nerve. Soon there is a cracking sensation conveyed to the hand as the roots
give way, and the nerve may then be drawn out entire. With care, either the
filaments of origin from the medulla or those from the cord may be extirpated
alone.— (BERNARD, op. cit., p. 736 ; and, Lemons sur la physiologic et la pathologic
du sysleme nerveux, Paris, 1858, tome ii., p. 296.)
1 Op. cit., p. 735. s See vol. i., Voice and Speech, p. 490, et seq.
NEKVOUS SYSTEM.
ments tliat have demonstrated the influence of the spinal
accessory nerve over these muscles have pointed out the des-
tination of the fibres that join the pneumogastric, which could
never have been done so satisfactorily by dissection. They
have shown further that the movements involved in phona-
tion are more or less independent of the respiratory move-
ments of the larnyx.
If the larnyx be exposed in a living animal, with all its
nervous connections intact, it wrill be seen to open widely
during inspiration, being passive in expiration. The wide
opening of the glottis at this time is due to the fact that,
after the operation, respiration is usually more or less la-
bored ; but if we carefully observe the parts when the respira-
tory acts are perfectly tranquil, the movements of the glottis
seem to be very slight. The larynx is then permanently
opened to a moderate degree, but the chink of the glottis is
slightly dilated with each expiration. If the recurrent laryn-
geal nerves, which are distributed to all of the muscles of
the larynx except the crico-thyroid, be now divided upon
both sides, the larynx is entirely paralyzed, and in cats and
young animals, in which the cartilages are soft and flexible,
the parts are occluded by the effort of inspiration, and death
takes place from suffocation. Of course the division of the
recurrent laryngeal nerves abolishes the voice, but it arrests
the other movements of the larynx as well. The distinction
thus established between the action of the spinal accessory
and the recurrent laryngeal nerves was fully illustrated by
Bernard, in the following experiments :
In a cat, in which the voice had been completely de-
stroyed by extirpation of both spinal accessory nerves, the
larynx was exposed. The glottis was seen dilated so as to
permit the free passage of air in respiration. The mucous
membrane retained its sensibility, and when the interior of
the larynx was irritated, a very slight but ineffectual effort
was made to close the glottis. It was impossible for the
animal to approximate the posterior points of attachment of
INTERNAL BRANCH OF THE SPINAL ACCESSORY. 175
the vocal cords, or to put the cords on the stretch. If such
irritation be applied to the larynx of an animal wi'th the
spinal accessory nerves intact, the glottis is instantly and
firmly closed.1
In a cat about five weeks old, both spinal accessory
nerves were extirpated, and the voice was thus destroyed.
Two days after, both recurrent laryngeal nerves were di-
vided, and the animal died almost immediately of suffo-
cation.2
These experiments show conclusively that the internal,
or communicating branch of the spinal accessory is the
nerve which presides over the movements of the larynx in
phonation. The filaments undoubtedly pass to the larynx
in greatest part through the recurrent laryngeal branches of
the pneumogastric ; but the recurrent laryngeals also con-
tain motor filaments from other sources, which are chiefly
concerned in the respiratory movements of the glottis.
Influence of the Internal Branch of the Spinal Accessory
upon Deglutition. — We must refer again to the experiments
of Bernard for an account of the influence of the spinal
accessory upon deglutition. There are two ways in which
deglutition is affected through this nerve: 1. When the
larynx is paralyzed as a consequence of extirpation of both
nerves, the glottis cannot be completely closed to pre-
vent the entrance of foreign bodies into the air-passages.
In rabbits particularly, it was rioted that particles of food
penetrated the trachea and found their way into the lungs.3
2. The spinal accessory furnishes numerous filaments to the
pharyngeal branch of the pneumogastric, and, through this
nerve, directly affects the muscles of deglutition ; but the
muscles animated in this way by the spinal accessory have a
1 BERNARD, op. «7., p. 745.
8 Loc. tit., p. 749.
3 BERNARD, Lemons sur la physiologic et la pathologie d*. systbne nervevx,
Paris, 1858, tome ii., p. 323.
112
176 NERVOUS SYSTEM.
tendency to draw the lips of the glottis together, while they
assist in passing the alimentary bolus into the oesophagus.
When these important acts are wanting, there is some diffi-
culty in the process of deglutition itself as well as danger of
the passage of alimentary particles into the larynx.
Influence of the Spinal Accessory upon the Heart. —
When we come to study the varied functions of the pneumo-
gastrics, we will discuss fully the mechanism by which the
contractions of the heart are arrested by galvanization of both
of these nerves in the neck. A very curious and interesting
observation by Waller has demonstrated that this influence,
whatever be its mechanism, is derived from the spinal acces-
sory, and necessarily comes through its communicating
branch. It has been found that a powerful current of gal-
vanism passed through the pneumogastric on one side will
arrest the action of the heart. Waller found that if he ex-
tirpated the spinal accessory on one side, the action of the
heart could not be arrested by galvanizing the pneumo-
gastric upon the same side ; but this result followed gal-
vanization of the pneumogastric upon the opposite side, on
which the connections with the spinal accessory were intact.
These phenomena, however, could not be observed until
from ten to twelve days had elapsed after the extirpation of
the spinal accessory.1 We have already seen, in treating of
the general properties of the nerves, that the irritability of
the motor nerves disappears in about four days after their
separation from the nerve-centres.2 In the observation just
referred to, it seemed necessary that a sufficient time should
elapse after extirpation of the spinal accessory for the irrita-
1 WALLER, Experiences sur les nerfs pneumogastriques et accessoires de Willis.
—Gazette medicate, Paris, 1856, 3eme serie, tome xi., p. 420.
In these experiments, Waller demonstrated by microscopical examination
the disorganization of both "branches of the spinal accessory, and showed that
their galvanization produced little, if any contraction in the muscles to which
these branches were distributed.
3 See p. 96u
EXTERNAL BRANCH, OF THE SPINAL ACCESSORY. 177
bility of the filaments that join the pneumogastric to become
extinct ; but the experiment is sufficient to show the direct
inhibitory influence of the spinal accessory on the heart.
The subject will be more fully considered, however, in con-
nection with the functions of the pneumogastrics.
Functions of the External, or Muscular Branch of the
Spinal Accessory. — The most interesting feature ' in the
recent researches into the functions of the spinal accessory
is, that experimentalists have been able to separate physio-
logically the internal from the external branch. Observa-
tions have conclusively demonstrated that the internal
branch, and the internal branch only, is directly concerned
in the vocal movements of the larynx, and, to a great ex-
tent, in the closure of the glottis during deglutition. It has
been noted, in addition, that animals in which both branches
have been extirpated present irregularity of the movements
of the anterior extremities and suffer from shortness of
breath after violent muscular exertion. The use of the cor-
responding extremities in the human subject is so different,
that it is not easy to make a direct application of these ex-
periments ; still, we can draw from them certain inferences
with regard to the functions of the external branch in man.
In prolonged vocal efforts, the vocal cords are put upon
the stretch, and the act of expiration is very different from
that in tranquil breathing. In singing, for example, the
shoulders are frequently fixed ; and this is done to some ex-
tent by the action of the sterno-cleido-mastoid and the trape-
zius. "We may suppose, then, that the action of the branch
of the spinal accessory which goes to these muscles has a cer-
tain synchronism with the action of the branch going to the
larynx and the pharynx ; the one fixing the upper part of
the chest so that the expulsion of the air through the glottis
may be more nicely regulated by the expiratory muscles,
and the other acting upon the vocal cords.1
1 It is unnecessary to make any further reference in detail to the admirable
178 NERVOUS SYSTEM.
In what is known to physiologists as muscular effort, the
mechanism of which has been discussed in another volume,1
the glottis is closed, the thorax is fixed after a full inspira-
tion, and respiration is arrested so long as the effort, if it be
not too prolonged, is continued. The same synchronism,
therefore, obtains in this as in prolonged vocal efforts. In
experiments in which the muscular branch only has been
divided, shortness of breath, after violent muscular effort, is
observed; and this is probably due to the want of syn-
chronous action of the sterno-cleido-mastoid and trapezius.
The irregularity in the movements of progression in
animals, in which either both branches or the muscular
branches alone have been divided, is due to anatomical
peculiarities. Bernard has observed these irregularities in
the dog and the horse, but they are not so well marked in
the cat. There have been no opportunities for illustrating
these points in the human subject.
Sublingual) or Hypoglossal Nerve (NiniK).
The last of the motor cranial nerves is the sublingual ;
and its functions are intimately connected with the physi-
ology of the tongue in deglutition and articulation, though
it is also distributed to certain of the muscles of the neck.
Physiological Anatomy. — The apparent origin of the sub-
lingual is from the medulla oblongata, in the groove between
the olivary body and the anterior pyramid, on the line of the
anterior roots of the spinal nerves. At this point, its root is
lormed of from ten to twelve filaments, which extend from,
the inferior portion of the olivary body to about the junction
of the upper with the middle third. These filaments of
origin are separated into two groups, superior and inferior.
From this apparent origin, the filaments have been traced
memoir of Bernard on the spinal accessory, in which the function of the ex-
ternal branch in the lower animals has been fully investigated by experiments.
1 See vol. Hi., Movements, p. 477.
•
SUBLINGTJAL NEEVE. 179
>
into the gray matter of the floor of the fourth ventricle, be-
tween the deep origin of the pneumogastric and the glosso-
pharyngeal. Though there is much difference of opinion
upon this point, it is probable, from the elaborate researches
of Dr. Dean,1 that some of the filaments of origin of these
nerves decussate in the floor of the fourth ventricle.
The superior and inferior filaments of origin of the nerve
unite respectively to form two bundles, which pass through
distinct perforations in the dura mater. These two bundles
then pass into the anterior condyloid foramen, and unite into
a single trunk as they emerge from the cranial cavity. In
some of the inferior animals, the calf, horse, pig, rabbit, dog,
and cat, there is a delicate filament arising from the latero-
posterior portion of the medulla, remarkable by the presence
of a small ganglion, which joins the trunk of the nerve as it
passes through the foramen. This was described by Mayer,
and more lately by Yulpian ; both of these observers having
noted it exceptionally in the human subject.8 Direct experi-
ments are wanting to show positively the physiological prop-
erties of this ganglionic root.
After the sublingual has passed out of the cranial cavity,
it anastomoses with several nerves. It sends a filament of
communication to the sympathetic as it branches from the
superior cervical ganglion. Soon after it has passed through
the foramen, it sends a branch to the pneumogastric. It
anastomoses by two or three branches with the upper two
cervical nerves, the filaments passing in both directions be-
tween the nerves. It anastomoses with the lingual branch of
the fifth, by two or three filaments passing in both directions.
In its distribution, the sublingual presents several re-
markable peculiarities.
Its first branch, the descendens noni, passes down the
1 DEAN, The Gray Substance of the Medulla Oblongata and Trapezium, Wash-
ington, 1864, p. 16.
8 VULPIAH, Sur la racine posterieure ou ganglionnaire du nerf hypoglosse.—
Journal de la physiologic, Paris, 1862, tome v., p. 5, et seq.
180 NERVOUS SYSTEM.
neck to the sterno-hyoid, sterno-thyroid, and omo-hyoid
muscles. From its relations with important vessels and
nerves, this branch possesses considerable surgical interest.
The thyro-hyoid branch is distributed to the muscle of
the same name.
The other branches are distributed to the stylo-glossus,
hyo-glossus, genio-hyoid, and genio-hyo-glossus muscles, their
terminal filaments going to the intrinsic muscles of the tongue.
It is thus seen that the sublingual nerve is distributed to
all of the muscles in the infra-hyoid region, the action of
which is to depress the larynx and the hyoid bone after the
passage of the alimentary bolus through the pharynx ; to one
of the muscles in the supra-hyoid region, the genio-hyoid ;
to most of the, muscles which move the tongue ; and to the
muscular fibres of the tongue itself. The action of these
muscles and of the tongue itself in deglutition has already
been fully discussed in another volume.1
Properties and Functions of the Sublingual. — There is
every reason to believe that the sublingual nerve is entirely
insensible at its origin from the medulla oblongata. The
fact that it arises from a continuation of the motor tract
of the spinal cord and has no ganglion upon its main
.root would lead to the supposition that it is an exclusively
motor nerve. In operating upon the roots of the spinal
accessory, when the origin of the sublingual is necessarily
exposed, Longet has irritated the roots in the dog without
any evidence of pain on the part of the animal.2 In the dog,
Yulpian has constantly found the small ganglionic root,3
which we have already mentioned as exceptional in the hu-
man subject. Such experiments, taken in connection with
the anatomical characters of the nerve, render it almost cer-
1 See vol. ii., Digestion, p. 189, el seq.
2 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 584.
8 VULPIAN, Sur la racine posterieure ou ganglionnaire du nerf hypoglosse.—
Journal de la physiologic, Paris, 1862, tome v., p. 7.
STJBLINGUAL NERVE. 181
tain that the main root is devoid of sensibility. They do
not, however, positively demonstrate the insensibility of the
ganglionic root, for a severe operation, it is well known, may
temporarily abolish the sensibility of nerves when this is not
very acute, as is seen in experiments upon the recurrent sen-
sibility of the anterior roots of the spinal nerves. Still, as
this filament is ordinarily absent in the human subject, there
can be little doubt that the sublingual at its origin js exclu-
sively motor.
All modern experimenters have confirmed the observa-
tions of Mayo 1 and of Magendie,2 with regard to the sensi-
bility of the sublingual after it has passed out of the cranial
cavity. The anastomoses of this nerve with the upper two
cervical nerves, the pneumogastric, and the lingual branch
of the fifth, afford a ready explanation of this fact. Accord-
ing to Bernard, this nerve possesses recurrent sensibility de-
rived from the fifth pair.8
The functions of the sublingual have already been so
fully considered under the head of deglutition, that they
need not be discussed elaborately in this connection. We
will here simply state the phenomena which follow stimula-
tion of the nerve and the division of both nerves in living
animals.
The sublingual may be easily exposed in the dog by
making an incision just below the border of the lower jaw,
dissecting down to the carotid artery, and following the ves-
sel upward until we see the nerve as it crosses its course.
On applying a feeble current of galvanism at this point,
there are evidences of sensibility, and the tongue is moved
convulsively at each stimulation.
The phenomena following section of both sublingual
1 MAYO, Anatomical and Physiological Commentaries, Number ii., London,
1823, p. 11.
8 MAGENDIE, Lecons sur les functions et les maladies du systeme nerveux, Paris,
1841, tome ii., p. 290.
3 BERNARD, Lecons sur la physiologic et la pathologic du systeme nerveux, Paris,
1858, tome ii., p. 241.
182 NERVOUS SYSTEM.
nerves point directly to their function. The most notable
fact observed after this operation is, that the movements of
the tongue are entirely lost, while the tactile and gustatory
senses are not affected. These phenomena have been accu-
rately described by Mayo,1 Panizza,3 Magendie,3 and many
others. Perhaps the most varied experiments made upon
animals are those of Panizza. These have been fully detailed
in connection with the subjects of mastication and degluti-
tion. They consist simply in loss of power over the tongue,
with considerable difficulty in deglutition. We have repeat-
edly noted all of these points and demonstrated them to
medical classes.
In the human subject, the sublingual is usually more or
less affected in hemiplegia. In these cases, as the patient
protrudes the tongue, the point is deviated. This is due to
the unopposed action of the genio-hyo-glossus upon the sound
side, which, as it protrudes the tongue, directs the point
toward the side affected with paralysis.
A disease of rather rare occurrence has lately been de-
scribed under the name of glosso-labial paralysis, which is
characterized by paralysis of the sublinguals, affecting also
the orbicularis oris, and frequently the intrinsic muscles of
the larynx. The phenomena referable to the loss of power
over the tongue correspond to those observed in animals
after section of the nerves. Patients affected in this way
experience difficulty in deglutition, and, in addition, we note
an interference with articulation, which cannot be observed
in experiments upon animals. "We lately had a case of this
disease under observation in the Bellevue Hospital, the phe-
nomena of which were peculiarly interesting from a physio-
logical point of view. This patient presented complete
paralysis of the tongue, with considerable difficulty in deglu-
tition, probably from the tongue-affection. The orbicularis
1 Loc. cit.
2 PANIZZA, Nouvelles recherches experimentales sur les nerfs. — Gazette medicate,
Paris, 1835, p. 419. 3 j^ ^
SUBLLXGUAL NERVE.
183
oris was also paralyzed. The paralysis probably extended
to the intrinsic muscles of the larynx, as little or no vocal
sound could be made. The patient was incapable of articu-
late language, and communicated entirely by signs.
MEDICAL
LIBRARY.
CHAPTER VII.
TRIFACIAL, OR TRIGEMINAL NERVE.
Physiological anatomy of the trifacial — Properties and functions of the trifacial
— Division of the trifacial within the cranial cavity — Immediate effects of
division of the trifacial — Remote effects of division of the trifacial — Effects
of division of the trifacial upon the organs of special sense — Division of the
trifacial before and behind the ganglion of Gasser — Communication with
the sympathetic at the ganglion of Gasser — Explanation of the phenomena
of disordered nutrition after division of the trifacial — Cases of paralysis of
the trifacial in the human subject.
A SINGLE nerve, the large root of the fifth pair, called
the trifacial, or the trigeminal, gives general sensibility to
the face and the head as far back as the vertex. This is one
of the most interesting of the cranial nerves, and is one of
the first that was experimented upon by physiologists. It
is interesting, not only as the great sensitive nerve of the
face, but from its connections with other nerves and its re-
lations to the organs of special sense. In studying the
physiology of this nerve, we must necessarily begin with its
physiological anatomy.
Physiological Anatomy. — The apparent origin of the
large root of the fifth is from the lateral portion of the pons
Yarolii, posterior and inferior to the origin of the small root,
from which it is separated by a few transverse fibres of white
substance. The deep origin is far removed from its point of
emergence from the encephalon. The roots pass entirely
through the substance of the pons, from without inward and
from before backward, without any connection with the
fibres of the pons itself. By this course it reaches the me-
TRIFACIAL NERVE. 185
dulla oblongata, where the roots divide into three bundles.
The anterior bundle passes from behind forward, between
the anterior fibres of the pons and the cerebellar portion of
the restiform bodies, to anastomose with the auditory nerve.1
The other bundles, which are posterior, pass, the one in the
anterior wall of the fourth ventricle to the lateral tract of the
medulla oblongata, and the other, becoming grayish in color,
to the restiform bodies, from which they may be followed as
far as the point of the calamus scriptorius. According to
Yulpian, a few fibres from the two sides decussate in the
median line in the anterior wall of the fourth ventricle.2
From this origin, the large root of the fifth passes ob-
liquely upward and forward to the ganglion of Gasser,
which is situated in a depression in the petrous portion of
the temporal bone on the internal portion of its anterior
face.
The Gasserian ganglion is semilunar in form (sometimes
it is called the semilunar ganglion), with its concavity looking
upward and inward.3 At the ganglion, the nerve receives
filaments of communication from the carotid plexus of the
sympathetic. This anatomical point is of importance in view
of some of the remote effects which follow division of the
fifth nerve through the ganglion in living animals.
It will be necessary only to describe in a general way
HIRSCHFELD, Systeme nerveux, Paris, 1866, p. 166. The anastomo-
sis of the auditory nerve has been denied (VFLPIAN, Essai sur Forigine de
plusieurs paires des nerfs craniens, These, Paris, 1853, p. 27), but it is admitted
by most anatomists.
2 Op. tit., p. 25.
3 The structure of this ganglion was first recognized by Gasser, Professor of
Anatomy in Vienna. His observations, however, were published by Hirsch, a
pupil of Gasser, in 1765 (HiRSCH, Paris quinti Nervorum encephali, Vienme,
1765, hi LUDWIG, Scriptores Nevrologiti minores selecti, Lipsiae, 1791, tomus i., p.
244, et seq.). Hirsch first gave it the name of Gasserian ganglion (p. 262).
Some authors call it the Casserian ganglion, probably confounding Gasser with
Casserius. Casserius, in his anatomical figures, describes many parts of the
brain and nerves, but says nothing of the gangh'on of the fifth (CASSERIUS,
Anatormche Tafeln, Franckfurt am Mayn, 1756).
186 NERVOUS SYS'LEM.
the numerous branches of distribution of the fifth nerve,
remembering that it is the great sensitive nerve of the
face.
At the ganglion of Gasser, from its anterior and external
portion, are given off a few small and unimportant branches
to the dura mater and tentorium.
From the convex border of the ganglion, the three great
branches arise that have given to the nerve the name of
trifacial or trigeminal. These are: 1, the ophthalmic; 2,
the superior maxillary ; 3, the inferior maxillary. The oph-
thalmic and the superior maxillary branch are derived en-
tirely from the sensory root. The inferior maxillary branch
joins with the motor root and forms a mixed nerve.
The ophthalmic branch, the first division of the fifth, is
the smallest of the three. Before it enters the orbit, it re-
ceives filaments of communication from the sympathetic,
sends small branches to all of the motor nerves of the eye-
ball, and gives off a small recurrent branch which passes be-
tween the layers of the tentorium.
Just before the ophthalmic branch enters the orbit by
the sphenoidal fissure, it divides into three branches ; the
lachrymal, frontal, and nasal.
The lachrymal, the smallest of the three, sends a branch
to the orbital branch of the superior maxillary nerve, passes
through the lachrymal gland, to which certain of its fila-
ments are distributed, and its terminal filaments go to the
conjunctiva and the integument of the upper eyelid.
The frontal branch, the largest of the three, divides into
the supra-trochlear and supra-orbital nerves. The supra-
trochlear passes out of the orbit between the supra-orbital
foramen and the pulley of the superior oblique muscle. It
sends in its course a long, delicate filament to the nasal
branch, and is finally lost in the integument of the forehead.
The supra-orbital passes through the supra-orbital foramen,
sends a few filaments to the upper eyelid, and supplies the
forehead, the anterior and median portions of the scalp, the
TEIFACIAL NERVE. 187
mucous membrane of the frontal sinus, and the pericranium
covering the frontal and 'parietal bones.
The nasal branch, before it penetrates the orbit, gives off
a long, delicate filament to the ophthalmic ganglion, consti-
tuting its sensory root. It then gives off the long ciliary
nerves, which pass to the ciliary muscle and iris. Its trunk
then divides into the external nasal, or infra-trochlearis, and
the internal nasal, or ethmoidal. The infra-trochlearis is dis-
tributed to the integument of the forehead and nose, to the
internal surface of the lower eyelid, the lachrymal sac, and the
caruncula. The internal nasal is distributed to the mucous
membrane, and also in part to the integument of the nose.
The superior maxillary branch of the fifth passes out of
the cranial cavity by the foramen rotundum, traverses the
infra-orbital canal, and emerges upon the face by the infra-
orbital foramen. Branches from this nerve are given off in
the spheno-maxillary fossa and the infra-orbital canal, before
it emerges upon the face. In the spheno-maxillary fossa, the
first branch is the orbital, which passes into the orbit, giving
off one branch, the temporal, which passes through the tem-
poral fossa by a foramen in the malar bone, and is distrib-
uted to the integument on the temple and the side of the
forehead ; another branch, the malar, which likewise emerges
by a foramen in the malar bone, is distributed to the in-
tegument over this bone. In the spheno-maxillary fossa,
are also given off two branches, which pass to the spheno-
palatine, or Heckel's ganglion. From this portion of the
nerve, branches are given off, the two posterior dental nerves,
which are distributed to the molar and bicuspid teeth, the
mucous membrane of the corresponding alveolar processes,
and to the antrum.
In the infra-orbital canal, a large branch, the anterior
dental, is given off to the teeth and mucous membrane of the
alveolar processes not supplied by the posterior dental nerves.
This nerve anastomoses with the posterior dental.
The terminal branches upon the face are distributed to
188 NERVOUS SYSTKM.
the lower eyelid (the palpebral brandies) ; to the side of the
nose (the nasal branches), anastomosing with the nasal
branch of the ophthalmic ; and to the integument and mu-
cous membrane of the upper lip (the labial branches).
The inferior maxillary is a mixed nerve, composed of the
inferior division of the large root and the small root. The
distribution of the motor filaments has already been de-
scribed under the head of the nerve of mastication.1 This
nerve passes out of the cranial cavity by the foramen ovale,
and then separates into the anterior division, containing
nearly all of the motor filaments, and the posterior division,
which is chiefly sensory. The sensory portion breaks up
into numerous branches :
1. The auriculo-temporal nerve supplies the integument
in the temporal region, the auditory meatus and the integu-
ment of the ear, the temporo-maxillary articulation, and the
parotid gland. It also sends important branches of commu-
nication to the facial.
2. The lingual branch is distributed to the mucous mem-
brane of the tongue as far as the point, the mucous mem-
brane of the mouth, the gums, and to the sublingual gland.
This nerve receives an important branch from the facial, the
chorda tympani, which has already been described.9 From
this nerve, also, are given off two or three branches which pass
to the submaxillary ganglion, constituting its sensory roots.
3. The inferior dental nerye, the largest of the three,
passes in the substance of the inferior maxillary bone, be-
neath the teeth, to the mental foramen, where it emerges
upon the face. The most important sensory branches are
those which supply the pulps of the teeth, and the branches
upon the face. The nerve, emerging upon the face by the
mental foramen, called the mental nerve, supplies the integ-
ument of the chin and the lower part of the face, the lower
lip, and sends certain filaments to the mucous membrane of
the mouth.
1 See page 141. 8 See page 143.
TEIFAC1AL NEEV1 .. 139
Properties and Functions of the Trif octal. — Our definite
knowledge with regard to the properties and functions of the
e root of the fifth nerve dates from the experiments by
Mayo, published in 1822. It is generally stated by authors
that the researches of Sir Charles Bell, in 1811, led natural-
. the idea that the ganglionic root of the fifth was entire-
ly nensory. We have already shown, by full references to
the paper printed by Sir Charles Bell, in 1811, that he there-
in attributed both motion and sensation to the anterior roots
of the spinal nerves, regarding the ganglionic roots as nerves
presiding over the functions of organic life.1 The mistake
made by authors in attributing the exact distinction between
the functions of the large root of the fifth and the small root
and the facial arises from the fact that a paper published
originally in the Philosophical Transactions, in 1821,2 is re-
printed with other memoirs, "with some additional explana-
tions." ! The additions to the original paper are in such a
form as to lead the reader to suppose that the author regard-
ed the large root of the fifth as exclusively sensory; but, in
the original paper, which we have carefully compared with
the reprint, the distinction between the motor and the sen-
sory root of the fifth is by no means clearly made.
In 1822, Herbert Mayo published an account of " experi-
ments to determine the influence of the portio dura of the
seventh, and of the facial branches of the fifth pair of nerves."
These experiments consisted in dividing the infra-orbital, in-
ferior maxillary, and frontal branches of the fifth, and the
branch from the fifth to the seventh, in asses, by which
it was demonstrated that these were exclusively sensory
nerves.4 In a second publication, the following year, it is
1 See page 71.
<J JiKi.L, On tJie Nerves ; giving an Account of some Experiments on their
Structure and Functions, which lead to a New Arrangement of t/ie System. —
riuloHophical Transactions, London, 1821, Part i., p. 398.
3 BELL, The Nervous System of the Human Body, as explained in a Series
of Papers read before the Royal Society of London, London, 1844, p. 33.
4 MAYO, Anatomical and Physiological Commentaries, Number i., London,
1822, p. 107, et seq.
190 NEBVOUS SYSTEM.
stated that the root of the fifth was divided in the cranial
cavity in pigeons ; 1 but this was with reference chiefly to the
movements of the iris, though Mayo notes that after division
of the nerve " the surface of the eyeball appears to have lost
its feeling."
In 1823, Fodera published an account of experiments in
which he had divided the roots of the fifth in living animals
(rabbits) by introducing a small knife through an opening
in the parietal bone, along the base of the skull, and cutting
through the roots near the Gasserian ganglion. The opera-
tion was followed by complete loss of sensibility upon the
side on which the nerve had been divided.8 In this and
other experiments, however, the animals died a short time
after the operation. The paper was presented to the Acad-
emy of Sciences, December 31, 1822, and was published at
about the same time as the experiments of Mayo.
In 1824, Magendie published an account of his experi-
ments on the fifth pair.3 He divided the nerve at its root,
by introducing a small stylet through the skull, and noted
immediate loss of sensibility on the corresponding side of
the face. Magendie was the first to succeed in keeping the
animals alive, observing certain interesting remote effects of
division of the nerve.
The operative procedure employed by Magendie has
been followed, with great success, by other physiologists,
particularly Bernard, to whose researches we are indebted
for many additional facts of interest concerning the func-
tions of the fifth nerve. As this is an operation which we
have frequently performed with success, following the mi-
1 MAYO, Anatomical and Physiological Commentaries, Number ii., London,
1823, p. 5.
2 FODERA, Recherches experimentales sur le systeme nerveux. — Journal de physi-
ologie, Paris, 1823, tome iii., p. 207.
3 MAGENDIE, De Vinfluence de la cinquieme paire de nerfs sur la nutrition et
les fonctions de Peril. — Journal de physiologic, Paris, 1824, tome iv., p. 176, et
seq. ; and, Suite des experiences sur les fonctions de la cinquieme paire, Ibid., p.
302, et seq.
TKIFACIAL NERVE. 191
nute directions laid down by Bernard, we will quote from
him in brief the different steps.
The nerve may be divided in the cranial cavity with tol-
erable certainty in rabbits, cats, dogs, and Guinea-pigs, but
it is most easily done in rabbits. It is difficult, from the
fact that one is working in the dark, and requires a
certain amount of dexterity, to be acquired only by
practice. The instrument used is represented in'
Fig. 9. It is made by Messrs. Tiemann & Co., of
Kew York. The operative procedure is as follows :
1. " The head of the rabbit is firmly held in the
left hand. The operator feels with the finger of the
right hand the tubercle situated in front of the ear,
formed by the condyle of the lower jaw. Behind
this tubercle, is a hard, osseous portion, the origin of
the auditory canal.
2. " The operator penetrates just behind the su-
perior border of the condyle, directing the point of
the instrument slightly forward to avoid passing
into the substance of the petrous portion of the tem-
poral bone, and thus passes more easily into the
middle temporal fossa ; at the same time the instru-
ment is directed a little upward to avoid slipping
into the zygomatic fossa and thus failing to enter
the cranial cavity.
3. "As soon as the instrument has penetrated
the cranium, which is recognized by the point be-
coming free, the pressure is arrested and the instru-
ment is directed downward and backward, its back sliding
along the anterior face of the bone, which should serve as a
guide in the operation.
4. " This point of departure — that is to say, the anterior
face of the bone — being found, the instrument is pushed
along, following its inferior border and proceeding gradu-
ally, as the instrument penetrates, pressing on the bone, the
resistance of which can be easily recognized. Soon, how-
113
192 NERVOUS SYSTEM.
ever, the operator feels, at a certain depth, that the bony
resistance ceases : he is then on the fifth pair, and the cries
of the animal give evidence that the nerve is pressed
upon.
5. l< It is at this moment that it is necessary to hold
firmly the instrument and the head of the animal ; then the
cutting edge is turned so as to be directed downward and
backward, at the same time pressing in this direction so as
to divide the nerve on the extremity of the petrous portion,
behind the ganglion of Gasser, if possible, or at least on the
ganglion itself.
6. " The instrument is then drawn back, pressing upon
the bone so as to accomplish completely the section of the
trunk of the fifth pair ; then it is withdrawn by passing over
the same course on the anterior face of the petrous portion
so as not to lacerate the cerebral substance.
" The accident to be feared in the operation is section of
the carotid when the instrument has penetrated too far, or
lesion of the cavernous sinus when it is pressed too far for-
ward." x
When this operation has been performed without acci-
dent, its immediate effects are very striking. The cornea
and the integument and mucous membrane on that side of
the head are instantaneously deprived of sensibility, and
may be pricked, lacerated, or burned without the slightest
evidence of pain on the part of the animal. Almost always
the small root of the fifth is divided as well as the large
root, and the muscles of mastication are paralyzed upon one
side ; but, with this exception, there is no paralysis of mo-
tion, sensation alone being destroyed upon one side.
Immediate Effects of Division of the Trifacial. — It is
hardly necessary to discuss the functions of the trifacial, af-
ter the statement of the effects which instantly follow upon
1 BERNARD, Lemons sur la physiologic et la pathologic du systeme nerveux,
Paris, 1858, .tome ii., p. 53.
TRJFACIAL NERVE. 193
its division, taken in connection with its physiological anat-
omy. The nerve has never been exposed in the cranial
cavity in living animals ; but its branches upon the face and
the lingual branch of the inferior maxillary division have
been operated upon and found to be exquisitely sensitive.
Longet and others have exposed the roots in animals imme-
diately after death, and have found that galvanization of the
large root carefully insulated produces no muscular contrac-
tion.1 All who have divided this root in living animals
must have recognized, not only that it is sensitive, but that
its sensibility is far more acute than that of any nervous
trunk in the body. It is much more satisfactory to divide
the nerve without etherizing the animal, as the evidence of
pain is an important guide in this delicate operation ; but
in using anaesthetics, we have never been able to bring an
animal under their influence so completely as to abolish the
sensibility of the root itself. For example, in cats that ap-
pear to be thoroughly etherized, as soon as the instrument
touches the nerve, there is more or less struggling. The
large root of the fifth, then, is an exclusively sensory nerve>
and its sensibility is more acute than that of any other of
the cerebro-spinal nerves.
The distribution of the branches of the large root of the
fifth indicates that it is the great sensitive nerve of the face.
It will be remembered, however, that its branches go large-
ly to the organs of special sense, and it is an interesting
question to determine whether or not these branches be en-
dowed with special as well as general sensibility.
Magendie thought, from his experiments upon animals,
that the fifth nerve was endowed with special sensory prop-
erties. He states distinctly that section of the nerve is im-
mediately followed by loss of taste, smell, hearing, and sight,
on the side operated upon.8 This view, however, has not
1 LOXGET, Traite de physiologic, Paris, 1869, tome iii., p. 487.
- MAGEXDIE, Suite des experiences sur les fondions de la cinquieme paire d«
nerfs. — Journal de physiologic, Paris, 1824, tome iv., p. 305, et scg.
In another volume of the same journal, Magecdie reports a case ha which the
194: NERVOUS SYSTEM.
been sustained by more recent experimenters ; and it is
probable that in some of the experiments of Magendie, other
nerves were divided as well as the fifth. This is a question
which will be touched upon again in connection with the
special senses ; suffice it to say at present that there is 110
evidence that branches of the fifth pair of nerves are en-
dowed with olfactory, auditory, or visual sensibility. This
statement is made without reserve by Miiller,1 who adduces
cases of paralysis of the fifth in the human subject in proof
of its correctness. It is often the case that the special senses
are affected as an indirect and remote consequence of lesion
of the fifth, or rather of filaments of the sympathetic con-
nected with the fifth ; but division of this nerve alone does
not immediately affect any of the special senses. The loss
of taste is due always to division of the chorda tympani.
As far as audition and olfaction are concerned, there are
no special effects immediately following section of the tri-
facial ; but there are interesting phenomena observed in
connection with the eye and the organs of taste.
At the instant of division of the fifth, by the method just
described, the eyeball is protruded and the pupil becomes
strongly contracted. This occurs in rabbits, and the contrac-
tion of the pupil was observed in the first operations of Ma-
gendie.2 The pupil, however, is usually restored to the nor-
mal condition in a few hours. Longet states that the pupil
is dilated by division of the fifth in dogs and cats.3 After
division of the nerve, the lachrymal secretion becomes very
much less in quantity ; but this is not the cause of the sub-
sequent inflammation, for the eyes are not inflamed, as was
shown by Magendie, even after extirpation of both lachrymal
sight in one eye was not extinct, the corresponding optic nerve being atrophied,
but by no means destroyed (La vue peui-elle etre conservee malgre la destruction
des nerfs optiques, tome viii., p. 27).
1 MULLER, Physiologic du systeme nerveux, Paris, 1840, tome i., p. 303.
8 Loc. tit.
8 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 489, note.
TRIFACIAL NERVE. 195
glands.1 The movements of the eyeball are not affected by
division of the fifth.
Another of the immediate effects of complete division of
the fifth is loss of general sensibility in the tongue. This
fact was noted by Mayo, in 1S23,3 and has been confirmed
by other physiologists. Most experiments upon the influ-
ence of the fifth over the general sensibility and the sense
of taste in the tongue have been made by dividing the
lingual branch of the inferior maxillary division. When
this branch is irritated, there are evidences of intense pain.
When it is divided, the general sensibility and the sense of
taste are destroyed in the anterior third or half of the tongue.
It will be remembered, however, that the chorda tympani
joins the lingual branch of the fifth as it passes between the
pterygoid muscles, and that section of this branch of the fa-
cial abolishes the sense of taste in the anterior third or half
of the tongue.3 If the gustatory properties of the lingual
branch of the fifth be derived from the chorda tympani,
lesions of the fifth not involving this nerve would be fol-
lowed by loss of general sensibility, but the taste would be
unaffected. This has been shown to be the fact by experi-
ments upon animals and certain cases of paralysis of general
sensibility of the tongue without loss of taste in the human
subject, reported by Schiff * and by Lussana,6 which will be
discussed more fully in connection with gustation.
Among the immediate effects of section of the fifth, is an
interference with the reflex phenomena of deglutition. In
some recent researches on the action of the sensitive nerves
1 MAGEXDIE, De I 'influence de la cinquieme paire des nerfs sur la nutrition et leg
fonctions de VceiL — Journal de physiologie, Paris, 1824, tome iv., p. 179.
2 MAYO, Anatomical and Physiological Commentaries, Number ii., London,
1823, p. 10.
3 See page 155, et seq.
4 SCHIFF, Lemons sur la physiologic de la digestion, Florence et Turin, 1867,
tome i., p. 103, et seq.
6 LUSSAXA, Recherches experimentales et observations pathologiques sur les nerfs
tugout. — Archives de physiologic, Paris, 1869, tome ii,, p. 27, et seq.
196 NERVOUS SYSTEM.
in deglutition, by Waller and Prevost, it was found, that after
section of the fifth upon both sides, it was impossible to ex-
cite movements of deglutition by stimulating the mucous
membrane of the velum palati. After section of the superior
laryngeal branches of the pneumogastrics, no movements
of deglutition followed stimulation of the mucous membrane
of the top of the larynx. In these experiments, wrhen the
fifth was divided on one side, stimulation of the velum upon
the corresponding side had no effect, while movements of
deglutition were produced by irritating the velum upon the
sound side.1 These experiments show that the fifth nerve
is important in the reflex phenomena of deglutition, as a
sensory nerve, ^ conveying the impression from the velum
palati to the nerve-centres. This action probably takes
place through filaments which pass from the fifth to the mu-
cous membrane through Meek el's ganglion.
Remote Effects of Division of the Trifacial. — After the
ordinary operation of dividing the fifth pair in the cranial
cavity, the immediate loss of sensibility of the integument
and mucous membranes of the face and head is usually sup-
plemented by serious disturbances in the nutrition of the
eye, the ear, and the mucous membranes of the nose and
mouth. This curious fact was noted by Magendie, in 1824 ;a
but it was observed by Mayo, in 1823, in a case of paralysis
of the fifth in the human subject.3 At a period varying
from a few hours to one or two days after the operation, the
eye upon the affected side becomes the seat of purulent in-
flammation, the cornea becomes opaque, ulcerates, the hu-
mors are discharged, and the organ is destroyed. Conges-
tion of the parts is usually very prominent a few hours after
1 WALLER ET PREVOST, J&tude relative aux nerfs sensitifs qui president anx phe-
nomenes reflexes de la deglutition. — Archives de physiologie, Paris, 1870, tome iii.,
p. 346, et seq.
2 Journal de physiologie, Paris, 1824, tome iv., pp. 178, 304.
3 MAYO, Anatomical and Physiological Commentaries, Number ii., London,
1823, p. 12.
TKIFACIAL NEK YE. 197
division of the nerve. At the same time, there is an in-
creased discharge from the mucous membranes of the nose
and mouth upon the affected side, and ulcers appear upon
the tongue and lips. It is probable, also, that disorders in
the nutrition of the auditory apparatus follow the opera-
tion, though these are not so prominent. These phenom-
ena undoubtedly led Magendie to advance the view that
section of the fifth involves destruction of the organs of
special sense,1 though, as we have seen, these results are con-
secutive and not immediate. Animals affected in this way
usually die in from fifteen to twenty days.
One of the most interesting facts, particularly in view of
the information derived from later observations, in connec-
tion with the early experiments of Magendie, is, that he noted
that " the alterations in nutrition are much less marked " *
when the division is effected behind the ganglion of Gasser,
than when it is done in the ordinary way through the gan-
glion. It is difficult enough to divide the nerve completely
within the cranium, and is almost impossible to make the
operation at will through or behind the ganglion, and the
phenomena of inflammation are absent only in exceptional
and accidental instances. 'Magendie offers no satisfactory
explanation of the differences in the consecutive phenomena
coincident with the locality of section of the nerve. The
facts, however, have been abundantly verified by Longet,8
Bernard,4 and other experimenters. In the numerous ex-
periments that we have made upon the fifth pair, we have
generally noted the consecutive inflammatory phenomena in
the order above described ; but in exceptional instances,
these phenomena have been wanting. The following ex-
periment illustrates these exceptional operations :
1 Loc. cit. 2 Journal de physiologic, Paris, 1824, tome iv., p. 304.
3 LONGET, Anatomic et physiologic du systemc ncrreux, Paris, 1842, tome il,
p. 162.
4 BERNARD, Lemons sur la physiologic ft la pathologic du systeme nerveux, Paris,
1858, tome ii., p. 60.
198 NERVOUS SYSTEM.
February 6, 1868, the fifth pair of nerves was divided
upon the left side in a full-grown rabbit in the ordinary way,
before the class at the Bcllevue Hospital Medical College.
There followed instant and complete loss of sensibility on
the left side of the face. Four days after, the animal having
been fed ad libitum with cabbage, the loss of sensibility was
still complete. There was very little redness of the conjunc-
tiva of the left eye, and a very slight streak of opacity, so
slight that it was distinguished with difficulty. Twelve days
after the operation, the sensibility of the left eye was dis-
tinct, but slight.1 There was 110 redness of the conjunctiva,
and the opacity of the cornea had disappeared. The animal
was in good condition, the line of contact of the upper with
the lower incisors, when the jaws were closed, was very
oblique. The animal was kept alive by careful feeding with
bread and milk for one hundred and seven days after the
operation, there never being any inflammation of the organs
of special sense. It died at that time of inanition, having
become very much emaciated. The animal never recovered
power over the muscles of mastication of the left side, and
the ineisors grew to a great length, interfering very much
with mastication, which seemed to be the cause of death.
Longet, in 1842, furnished a satisfactory explanation of
the absence of inflammation in certain cases of division of
the fifth. He attributed the consecutive inflammation in
most experiments to lesion of the ganglion of Gasser and
of the sympathetic connections, which are very numerous at
this point. These sympathetic filaments are avoided when
the section is made behind the ganglion.2
The explanation of the phenomena of disordered nutri-
tion in the organs of special sense, particularly the eye, fol-
io wing division of the fifth, is not afforded by the section of
this nerve alone ; for, as we have seen, when the loss of sen-
1 We have observed in other experiments gradual return of sensibility, after
what appeared to have been complete division of the fifth.
2 LONGET, Anatomic el physiologic du systeme nerveux, Paris, 1842, tome ii.,
p. 162.
TEEFACIAL NERVE. 199
eibility is complete after division of the nerve behind the
Gasserian ganglion, these results may not follow. Xor are
they explained by deficiency in the lachrymal secretion, for
they are not observed when both lachrymal glands have
been extirpated. They are not due to exposure of the eye-
ball, for they do not follow upon section of the facial. Xor
are they due simply to an enfeebled general condition, for,
in the experiment we have detailed, the animal died of inani-
tion after section of the nerve, without any evidences of in-
flammation. In view of the fact that section of sympathetic
filaments is well known to modify the nutrition of parts to
which they are distributed, producing congestion, increase in
temperature, and other phenomena, it is rational to infer
that the modifications in nutrition which follow section of
the fifth after it receives filaments from the sympathetic sys-
tem, not occurring when these sympathetic filaments escape
division, are to be attributed to lesion of the sympathetic,
and not the division of the sensory nerve itself.
A farther explanation is demanded for the inflamma-
tory results which follow division of the sympathetic fila-
ments joining the fifth, inasmuch as division of the sym-
pathetic alone in the neck produces simply exaggeration of
the nutritive processes, as evidenced chiefly by local increase
in the animal temperature, and not the well-known phenom-
ena of inflammation.
It has been remarked by Bernard, that the " alterations
in nutrition appear more promptly in animals that are enfee-
bled." ' Section of the small root of the fifth, which is un-
avoidable when the nerve is divided in the cranial cavity,
generally interferes so much with mastication as to influence
seriously the general nutrition ; and this might modify the
1 BERNARD, Lemons sur la physiologieet la pathologic du systtmc neiveux, Paris,
1858, tome ii., p. 62. Barnard (op. cit., p. 518), in discussing the effects upon
calorification and nutrition of the face of division of the sympathetic in the neck,
states that " the effects of calorification of the great sympathetic may be trans-
formed into inflammatory phenomena when the animal becomes enfeebled." He
divided the sympathetic with the pneumogastric in the neck of a dog, on the
200 NEKVOTJS SYSTEM.
nutritive processes in delicate organs, like the eye, so as to
induce those changes which are called inflammatory. The
following observation, communicated by Dr. "W. H. Mason,
Professor of Physiology in the Medical Department of the
University of Buffalo, is very striking in this connection :
The fifth pair of nerves was divided in a cat in the ordi-
nary way. By feeding the animal carefully with milk and
finely-chopped meat, the nutrition was maintained at a high
standard, and no inflammation of the eye occurred for about
four weeks. The supply of food was then diminished to
about the quantity it would be able to take without any spe-
cial care, when the eye became inflamed, and perforation of
the cornea and destruction of the organ followed. The ani-
mal was kept for about five months ; at the end of which
time, sensation on the affected side, which had been gradu-
ally improving, was completely restored.1
The explanation we have to offer of the consecutive in-
flammatory effects of section of the fifth with its communicat-
ing sympathetic filaments is the following : By dividing the
sympathetic, the eye and the mucous membranes of the nose,
mouth, and ear are rendered hypersemic, the temperature is
probably raised, and the processes of nutrition are exagger-
ated. This condition of the parts would seem to require a
full supply of nutritive material from the blood, in order to
maintain the condition of exaggerated nutrition ; but when
the blood is impoverished, probably as the result of defi-
ciency in the introduction of nutritive matter, from paraly-
left side. A few days after, tie made experiments on the salivary secretion, and
finally took away a portion of the cephalo-rachidian fluid. " This last operation
made the animal sick and produced an inflammation of the nervous centres :
death occurred five days after. What was remarkable was that the mucous
membranes on the side of the face corresponding to the section of the sympa-
thetic became the seat of violent inflammation, from the moment that the animal
began to become enfeebled from the disease. There was abundant suppuration
from the nostril, the buccal mucous membrane, and the conjunctiva of the left
side, while on the opposite side the corresponding mucous membranes were in
the normal condition."
1 Written communication from Prof. Mason.
TRIFACIAL NERVE. 201
6is of the muscles of mastication upon one side, the nutri-
tive processes in these delicate parts are seriously modified,
so as to constitute inflammation. The observation just de-
tailed is an argument in favor of this view ; for here the in-
flammatory action seemed to be arrested when the action of
the paralyzed muscles was supplied by careful feeding. "With
this view, the disorders of nutrition observed after division of
the fifth may properly be referred to the sympathetic system.
Pathological facts in confirmation of experiments upon
the fifth pair in the lower animals are not wanting ; but it
must be remembered that, in cases of paralysis of the nerve
in the human subject, it is not always possible to locate ex-
actly the seat of the lesion and to appreciate fully its extent,
as can be done when the nerve is divided by an operation.
In studying these cases, it sometimes occurs that the phe-
nomena, particularly those of modified nutrition, are more
or less contradictory.
In nearly all the works on physiology, we find references
to cases of paralysis of the fifth in the human subject. One
of the most interesting is the case already referred to, re-
ported by Mayo, which was published before the experi-
ments of Magendie.1 Numerous cases of this kind have
been collected by Longet.* In the appendix to the work of
Sir Charles Bell on the Nervous System, several cases are
reported,3 observed by himself and collated from various
sources. We have already referred to the cases cited by
Schiff and by Lussana, some of which showed alteration of
taste, while in others this symptom was absent.4 In a re-
cent article by Dr. H. D. Noyes, Professor of Ophthalmol-
ogy in the Bellevue Hospital Medical College, two interest-
1 See page 196.
2 LONGET, Anatomic et physiologic du systeme nerveux, Paris, 1842, tome ii.,
p. 191, et seq.
3 BELL, The Nervous System of the Human Body, London, 1844, Appendix.
4 See page 195.
It is unnecessary to cite all the cases reported of paralysis of the fifth, but
they are quite numerous. In addition to those already referred to, the following
202 NEEVOUS SYSTEM.
ing cases are reported, which we had an opportunity of ex-
amining during the progress of treatment. In both of these
cases, there was inflammation of the eye. In one case, the
tongue was entirely insensible upon on side, but there was
no impairment of the sense of taste. An interesting feature
in one of the cases was the fact that an operation upon the
eyelid of the affected side was performed without the slight-
est evidence of pain on the part of the patient.1
These cases of paralysis of the fifth in the human subject
in the main confirm the results of experiments upon the in-
ferior animals. In all the cases in wrhich the fifth nerve
alone was involved in the disease, without the portio dura
of the seventh, there was simply loss of sensibility upon one
side, the movements of the superficial muscles of the face be-
ing unaffected. When the small root was involved, the mus-
cles of mastication upon one side were paralyzed ; but in cer-
tain cases in which this root escaped, there was no muscular
paralysis. The sense of sight, hearing, and smell, except as
they were affected by consecutive inflammation, were little,
if at all, disturbed in uncomplicated cases. The sense of
taste in the anterior portion of the tongue was perfect, except
in those cases in which the seventh, the chorda tympani, or
the lingual branch of the fifth after it had been joined by the
chorda tympani, was involved in the disease. In some cases,
there was no alteration in the nutrition of the organs of spe-
cial sense ; but in this respect the facts with regard to the
seat of the lesion are not so satisfactory as in experiments
upon the lower animals, it being difficult, in most of them,
to limit the exact boundaries of the lesion.
are the most important and satisfactory in their details : The case reported by
Montault (Journal de physiologic, Paris, 1829, tome ix., p. 113) ; a case by Dr.
Beveridge (Medical Times and Gazette, London, 1868, No. 921, p. 199); a case
by Althaus (Medico- Chirurgical Transactions, London, 1869, vol. Hi., p. 27) ; and
two cases by Rosenthal (Medicinische Jahrbucher, Wien, 1870, Bd. xix., Heft ii.
und iii., S. 163).
1 NOTES, Paralysis of the Fifth Cerebral Nerve, and its Effects. — New York
Medical Journal, 1871, vol. xiv., p. 163, et seq.
CHAPTEK VIII.
PNEUMOGASTRIC!, OK PAR VAGUM NERVE.
Pneumogastric nerve (second division of the eighth) — Physiological anatomy —
Properties and functions of the pneumogastric — General properties of the
roots — Properties and functions of the auricular nerves — Properties and
functions of the pharyngeal nerves — Properties and functions of the supe-
rior laryngeal nerves — Properties and functions of the inferior, or recurrent
laryngeal nerves — Properties and functions of the cardiac nerves, and influ-
ence of the pneumogastrics upon the circulation — Depressor-nerve of the
circulation — Properties and functions of the pulmonary branches, and influ-
ence of the pneumogastrics upon respiration — Properties and functions of
the oesophageal nerves — Properties and functions of the abdominal branches
— Influence of the pneumogastrics upon the liver — Influence of the pneumo-
gastrics upon the stomach and intestines — Summary of the distribution,
properties, and functions, of the pneumogastrics.
OF all the nerves emerging from the cranial cavity, the
pneumogastric, the second division of the eighth pair, pre-
sents the greatest number of anastomoses, the most remark-
able course, and the most varied and interesting functions.
Arising from the medulla oblongata by a purely sensory
root, it communicates with at least five motor nerves in its
course, and is distributed largely to muscular tissue, both of
the voluntary and the involuntary variety. Finally, there
is no nerve that has been the subject of such extended and
elaborate anatomical and physiological investigations, and
none, concerning the properties and exact functions of which
there has been so much difference of opinion.
TTe shall have to treat of the influence of the pneumo-
gastric upon the act of deglutition, the heart and circulatory
204: NERVOUS SYSTEM.
system, the respiratory system, the stomach, intestines, and
various glandular organs. An indispensable introduction to
this study is a description of its physiological anatomy.
Physiological Anatomy. — The apparent origin of the
pneumogastric is from the lateral portion of the medulla
oblongata, just behind the olivary body, between the roots
of the glosso-pharyngeal and of the spinal accessory. The
deep origin '& mainly from what is sometimes called the
nucleus of the pneumogastric, in the inferior portion of the
gray substance in the floor of the fourth ventricle. The
course of the fibres, traced from without inward, is some-
what intricate. The description of these, given by Yulpian,
in 1853, has been pretty generally verified by more recent
dissections, as well as by microscopical investigations.
Yulpian regards the deep origins of the pneumogastric
and glosso-pharyngeal nerves as, in the main, identical.
Tracing the filaments from without inward, he was able to
follow them in four directions. The anterior filaments pass
from without inward, first very superficial and directed
toward the olivary body, but turning before they reach the
olivary body, they pass deeply into the substance of the res-
tiform body, in which they are lost. The posterior fila-
ments are superficial, and pass, with the fibres of the resti-
form body, toward the cerebellum. Of the intermediate
filaments, the anterior pass through the restiform body, the
greatest number extending to the median line in the floor
of the fourth ventricle. A few fibres are lost in the middle
fasciculi of the medulla, and a few pass toward the brain.
The posterior intermediate filaments traverse the restiform
body to the floor of the fourth ventricle, when some pass to
the median line, and others descend in the substance of the
medulla.1 Yulpian states that he has not been able to fol-
low the fibres of origin of the pneumogastrics beyond the
1 VULPIAN, JEssai sur Vorigine de plusieurs paires des nerfs craniens, These,
Paris, 1853, p. 39.
PNEUMOGASTEIC KEKVE. 205
median line, but more recent observations leave no doubt
of the fact that many of these fibres decussate in the floor
of the fourth ventricle.1
There are two ganglionic enlargements belonging to the
pneumogastric. In the jugular foramen, is a well-marked,
grayish, ovoid enlargement, from one-sixth to one-fourth of
an inch in length, called the jugular ganglion, or the gan-
glion of the root. This is united by two or three filaments
with the ganglion of the glosso-pharyngeal. It is a true gan-
glion, containing nerve-cells. After the nerve has emerged
from the cranial cavity, it presents on its trunk another
grayish enlargement, from half an inch to an inch in length,
called the ganglion of the trunk. This is of rather a plexiform
structure, the white fibres being mixed with grayish fibres
and nerve-cells.
The exit of the nerve from the cranial cavity is by the
jugular foramen, or posterior foramen lacerum, in company
with the spinal accessory, the glosso-pharyngeal, and the
internal jugular vein.
Anastomoses. — The filaments of communication which
the pneumogastric receives from other nerves are interesting
from their great importance and their varied sources. The
most important of these is the branch from the spinal acces-
sory. There are occasional filaments of communication
which pass from the spinal accessory to the ganglion of the
root, but they are not constant. After both nerves have
emerged from the cranial cavity, an important branch of
considerable size passes from the spinal accessory to the
pneumogastric, with which it becomes closely united. Ex-
periments have shown that these filaments from the spinal
accessory pass in great part to the larynx by the inferior
laryngeal nerves.
In the aquseductus Fallopii, the facial nerve gives off a
1 DEAN, The Gray Substance of the Medulla Oblongata and Trapezium, Wash-
ington, 1864, p. 27.
206 NERVOUS SYSTEM.
filament of communication to the pneumogastric at the gan-
glion of the root. This filament, joined at the ganglion by
sensory filaments from the pneumogastric and some fila-
ments from the glosso-pharyngeal, is called the auricular
branch of Arnold. By some anatomists, it is regarded as a
branch from the facial,1 and by others it is described with
the pneumogastric.8
Two or three small filaments of communication pass
from the sublingual to the ganglion of the trunk of the
pneumogastric.'
At the ganglion of the trunk, the pneumogastric gener-
ally receives filaments of communication from the arcade
formed by the anterior branches of the first two cervical
nerves. These, however, are not constant.
The pneumogastric is connected with the sympathetic
system by numerous delicate filaments of communication re-
ceived from the superior cervical ganglion, passing in part
upward toward the ganglion of the root of the pneumogas-
tric, and in part transversely and downward. These fila-
ments are frequently short, and, as it were, bind the sympa-
thetic ganglion to the trunk of the nerve. The main trunk
of the pneumogastric and its branches receive a few delicate
filaments of communication from the middle and inferior
cervical and the upper dorsal ganglia of the sympathetic.
The pneumogastric frequently sends a very delicate fila-
ment to the glosso-pharyngeal nerve, at or near the gan-
glion of Andersch. Branches from the pneumogastric join
branches from the glosso-pharyngeal, the spinal accessory,
and the sympathetic, to form the pharyngeal plexus.
Distribution. — In describing the very extensive distribu-
tion of the pneumogastrics, while the nerves upon the two
sides do not present any important differences in the desti-
nation of their filaments as far down as the diaphragm, it
1 HIRSCHFELD, Systeme nerveux, Paris, 1866, p. 205.
2 SATPEY, Traite cTanxtomie, Paris, 1852, tome ii., p. 287.
PXEUMOGASTRIC NERVE. 207
will be seen that the abdominal branches are not the same.
The most important branches are the following :
1. Auricular.
2. Pharyngeal.
3. Superior laryngeal.
4. Inferior, or recurrent laryngeal.
5. Cardiac, cervical and thoracic.
6. Pulmonary, anterior and posterior.
7. (Esophageal.
8. Abdominal.
The auricular nerves are sometimes described in connec-
tion with the facial. They are given off from the ganglion
of the trunk, and are composed of filaments of communica-
tion from the facial and from the glosso-pharyngeal, as well
as of filaments from the pneumogastric itself. The nerve
thus constituted is distributed to the integument of the up-
per portion of the external auditory meatus, and a small
filament, according to Sappey, is sent to the membrana
tympani.1
The pharyngeal nerves are very remarkable in their
course. They are given off from the superior portion of
the ganglion of the trunk, and contain a large number of
the filaments of communication which the pneumogastric
receives from the spinal accessory. In their course by the
sides of the superior constrictor muscles of the pharynx,
these nerves anastomose with numerous filaments from the
glosso-pharyngeal and the superior cervical ganglion of the
sympathetic, to form what is known as the pharyngeal
plexus. The ultimate filaments of distribution pass to the
muscles and the mucous membrane of the pharynx. Physi-
ological experiments have shown that the motor influence
transmitted to the pharyngeal muscles through the pharyn-
geal branches of the pneumogastric is derived from the spi-
nal accessory.2
The superior laryngeal nerves are given off from the
1 SAPPEY, Traite cT anatomic, Paris, 1852, tome ii., p. 287. 8 See page 175.
114
208 NERVOUS SYSTEM.
lower part of the ganglion of the trunk. Their filaments
come from the side opposite to the point of junction of the
pneumogastric with the communicating branch from the spi-
nal accessory, so that probably the superior laryngeals con-
tain few if any motor fibres from this nerve. The superior
laryngeal gives off the external laryngeal, a long, delicate
branch, which gives a few filaments to the inferior con-
strictor of the pharynx, and is distributed to the crico-thy-
roid muscle and the mucous membrane of the ventricle of
the larynx. The external laryngeal anastomoses with the
inferior laryngeal and with the sympathetic. The internal
branch is distributed to the mucous membrane of the epi-
glottis, the base of the tongue, the aryteno-epiglottidean fold,
and the mucous membrane of the larynx as far down as the
true vocal cords. A branch from this nerve, in its course
to the larynx, penetrates the arytenoid muscle, to which it
sends a few filaments, but these are all sensory. This branch
also supplies the crico-thyroid muscle. It anastomoses with
the inferior laryngeal nerve. An important branch, de-
scribed by Cyon and Ludwig, in the rabbit, under the name
of the depressor-nerve, arises by two roots, one from the su-
perior laryngeal and another from the trunk of the pneumo
gastric, passes down the neck by the side of the sympathetic,
and, in the chest, joins filaments from the thoracic sympa-
thetic, to penetrate the heart between the aorta and the
pulmonary artery.1 This nerve will.be referred to more
particularly in connection with the influence of the pneu-
mogastrics upon the circulation.
It is important, from a physiological point of view, to
note that the superior laryngeal nerve is the nerve of sensi-
bility of the upper part of the larynx, as well as the supra-
laryngeal mucous membranes, and that it animates a single
muscle of the larynx, the crico-thyroid, and the inferior con-
strictor of the pharynx.
1 CYON ET LUDWIG, Action reflexe d?un des nerfs sensibles du, cceur sur les nerfs
vaso-moteur&, — Journal de ranatomie, Paris, 1867, tome iv., p. 472, el seq.
PXEUMOGASTRIC NERVE. 209
The inferior, or recurrent laryngeal nerves present some
slight differences in their anatomy upon the two sides. Upon
the left side, the nerve is the larger, and is given off at the
arch of the aorta. Passing beneath this vessel, it ascends
in the groove between the trachea and the O3sophagus. In
its upward course, it gives off certain filaments which join
the cardiac branches, filaments to the muscular tissue and
mucous membrane of the upper part of the oesophagus, fila-
ments to the mucous membrane and the inter-cartilaginous
muscular tissue of the trachea, one or two filaments to the in-
ferior constrictor of the pharynx, and a branch which joins
the superior laryngeal. Its terminal branches penetrate the
larynx behind the posterior articulation of the thyroid with
the cricoid cartilage, and are distributed to all of the intrin-
sic muscles of the larynx, except the crico-thyroids, which
are supplied by the superior laryngeal.
Upon the right side, the nerve winds from before back-
ward around the subclavian artery, and has essentially the
same course and distribution as upon the left side, except
that it is smaller and its filaments of distribution are not so
numerous.
The important physiological point connected with the
anatomy of the recurrent laryngeals is that they animate all
of the intrinsic muscles of the larynx, except the crico-thy-
roid. Experiments have shown that these nerves contain
numerous filaments from the spinal accessory.
The cervical cardiac branches, two or three in number,
arise from the pneumogastrics at different points of the cer-
vical portion and pass to the cardiac plexus, which is formed
in great part of filaments from the sympathetic. The tho-
racic cardiac branches are given off from the pneumogastrics
below the origin of the inferior laryngeals, and join the car-
diac plexus.
The anterior pulmonary branches are few and delicate
as compared with the posterior branches. They are given
off below the origin of the thoracic cardiac branches, send
210 NERVOUS SYSTEM.
a few filaments to the trachea, then form a plexus which
surrounds the bronchial tubes and follows the bronchial tree
to its terminations in the air-cells. The posterior pulmonary
branches are larger and more numerous than the anterior.
They communicate freely with sympathetic filaments from
the upper three or four thoracic ganglia, and then form the
great posterior pulmonary plexus. From this plexus, a few
filaments go to the inferior and posterior portion of the tra-
chea ; a few pass to the muscular tissue and mucous mem-
brane of the middle portion of the oesophagus ; and a few
are sent to the posterior and superior portion of the pericar-
dium. The plexus then surrounds the bronchial tree, and
passes with its ramifications to the pulmonary tissue, like the
corresponding filaments of the anterior branches. According
to Sappey, the pulmonary branches are distributed to the mu-
cous membrane, and not to the walls of the blood-vessels.1
The cesophageal branches take their origin from the
pneumogastrics above and below the pulmonary branches.
These branches from the two sides join to form the cesopha-
geal plexus, their filaments of distribution going to the mus-
cular tissue and the mucous membrane of the lower third
of the oesophagus.
The abdominal branches are quite different in their dis-
tribution upon the two sides.
On the left side, the nerve, which is situated anterior to
the cardiac opening of the stomach, immediately after its
passage by the side of the oesophagus into the abdomen, di-
vides into numerous branches, which are distributed to the
muscular walls and the mucous membrane of the stomach.
As the branches pass from the lesser curvature, they take a
downward direction and go to the liver, and, with another
branch running between the folds of the gastro-hepatic
omentum, follow the course of the portal vein in the hepatic
substance. The branches of this nerve anastomose with the
nerve on the right side and with the sympathetic.
1 SAPPET, Traite tfanatomie, Paris, 1852, tome ii., p. 294.
PNEUMOGASTKIC NERVES. 211
The right pneumogastric, situated posteriorly, at the
cesophageal opening of the diaphragm, sends a few filaments
to the muscular coat and the mucous membrane of the
stomach, passes backward, and is distributed to the liver,
spleen, kidneys, suprarenal capsules, and finally to the whole
of the small intestine.
The branches to the small intestine are very important.
These were accurately described in 1860, by Kollmann, in
an elaborate and beautifully-illustrated prize-essay. In the
plate showing the distribution of this nerve, it is seen that
the branches to the intestine are very numerous. Accord-
ing to these researches, the branches described belong to the
pneumogastric itself, and are not derived from the sympa-
thetic.1 When we come to treat of the action of the pneu-
mogastric upon the small intestine, it will be seen that the
anatomical researches by Kollmann are fully confirmed by
physiological experiments. Before the nerves pass to the
intestines, there is a free anastomosis and interchange of
filaments between the right and the left pneumogastric.
Properties and Functions of the Pneumogastric Nerves.
There is no nerve in the body that has been the subject
of so many experiments, and concerning which so much has
been written, as the pneumogastric. Its accessible position
in many parts of its course, its extensive connections with
the digestive, the respiratory, and the circulatory system,
and the evident importance of its relations, have rendered
the literature connected with its physiology somewhat redun-
dant. We do not propose to discuss in full all of the views
entertained from time to time with regard to its functions,
but to state merely what seem to be well-ascertained facts,
and the most reasonable inferences, where the facts are diffi-
1 KOLLMANN, Ueber den Verlauf des Lungenmagennerven in der Bauchhole.
Mne Prdsschrift. — Zeitschrift fur wissenschafiliche Zoologie, Leipzig, 1860, Bd. x.,
S. 413, et seq.
212 NERVOUS SYSTEM.
cult of demonstration. In treating cf the functions of this
nerve, we shall be compelled to make constant reference to
its anatomy, and for that reason have described pretty fully
in detail most of the important points in its connections and
distribution.
Although the extensive distribution of the pneumogas-
trics and their importance will necessitate a long discussion
of their physiology, we shall endeavor to separate the points
to be considered distinctly, and simplify the subject as much
as possible.
We shall first treat of the general properties of those fila-
ments derived from the true roots of the nerves, and, follow-
ing them in their course, shall note the properties derived
from their connections with other nerves.
We shall then treat of the properties of the different
branches of the nerves, under distinct heads, taking up these
branches as they are given off, from above downward. In
this, we shall consider first the properties and functions
of the auricular branches ; next, of the pharyngeal branches,
with their influence upon the action of the pharynx in deglu-
tition ; next, the superior and inferior laryngeal branches,
with their relations to the physiology of the larynx ; next
the cardiac branches, with their influence on the move-
ments of the heart and the circulation ; next, the pulmonary
branches, with the function of the nerves in connection with
respiration ; next, the oesophageal branches, in connection
with the influence of the nerves upon the action of the
oesophagus, in deglutition ; next, the abdominal branches,
with the influence of the nerves in connection with diges-
tion and the functions of the abdominal viscera. By divid-
ing up, in this way, the action of the pneumogastrics, it is
hoped that their physiology may be relieved of much of
the complexity in which it is apparently involved.
General Properties of the Hoots of Origin of the Pneu-
mogastrics.— All who have operated on the pneumogastrics
PXEUMOGASTEIC NERVES. 213
in the cervical region in living animals have noted their ex-
ceedingly dull sensibility, as compared with the ordinary
sensory nerves. Bernard, indeed, states that in this region
they are generally insensible ; 1 but we have usually found,
in dogs at least, that their division is attended with slight
evidences of pain. Without citing in detail all the experi-
ments on this point, it is sufficient to state that some physi-
ologists, on galvanizing or otherwise irritating the roots of
the nerves in animals just killed, have noted movements of
the muscles of deglutition, of the oesophagus, and the muscu-
lar coats of the stomach. These experiments have led to the
opinion that the proper roots of the nerves are motor as well
as sensory. It becomes, therefore, a difficult as well as an
important point to determine whether or not the roots be
of themselves exclusively sensory or mixed.
In discussing the properties of the roots, we shall rely
almost entirely upon direct experiments ; though the argu-
ments drawn from their anatomical characters, in the pres-
ence of ganglia and the deep origin of their fibres, point
strongly to their sensory character.
It is impossible to stimulate the roots, before they haA^e
received motor filaments from other nerves, in living ani-
mals, and the experiments are therefore made upon animals
just killed, before the nervous irritability has disappeared.
If the true roots of the nerves be exclusively sensory, their
galvanization in animals just killed should produce, by di-
rect action, no muscular contraction. If the roots contain
any motor filaments, contraction of muscles should follow
their stimulation. The proper physiological conditions in
such experiments are the following :
1. It is necessary to stimulate the roots so that the fila-
ments from the spinal accessory and other motor nerves be
not involved.
2. It is important to ascertain, provided movements follow
such irritation, whether or not they be due to reflex action.
1 BERNARD, Systeme nerveux, Paris, 1858, tome ii., p. 345.
214: NERVOUS SYSTEM.
The first of these conditions is easily fulfilled. All that
is necessary is to stimulate the roots before the nerves have
received any anastomosing filaments. To avoid contractions
of muscles due to reflex action, it is best to divide the roots
and to stimulate their distal portion. If it be true that
stimulation of the distal extremities of the roots, the irrita-
tion so applied as not to involve communicating filaments
from motor nerves, and not to be conveyed to the centres,
producing reflex movements through other nerves, does not
produce any movements, it is fair to assume that the true
filaments of origin are exclusively sensory. The facts upon
this point demand careful and critical study ; and it will be
proper to discard the earlier experiments, made before the
mechanism of reflex action had been satisfactorily estab-
lished.
If the experiments of Longet be accepted without re-
serve, they prove — as conclusively as is possible without ex-
posing the roots in living animals, an operation which is
impracticable — that the true filaments of origin of the pneu-
mogastrics are exclusively sensory; at least, that the nerve
contains no motor filaments except those derived from other
nerves. The following quotation gives the essential points
in these experiments :
" In dogs of large size and in horses, I have isolated in
the cranium, with the most minute care, the pneumogastric
of the medulla oblongata and the superior filaments of the
spinal accessory (internal ~branch\ in order to avoid all reflex
movement and any derivative current upon the last-named
nerve ; I then immediately caused the current to act exclu
sively upon the filaments of origin of the pneumogastric,
without having ever seen the slightest contraction super-
vene, either in the muscles of the larynx or pharynx, or in
the muscular tunic of the oesophagus, or elsewhere.
" But also I have never failed to demonstrate to all those
who witnessed my experiments, how it is easy to obtain op-
posite results in neglecting only one precaution : it suffices,
PXEUMOGASTRIC XERVES. 215
for example, to slightly moisten the slip of glass or oiled silk
which serves to isolate the two nerves, in order that the cur-
rent should act immediately upon the superior filaments of
the spinal accessory, from which we have marked contrac-
tions in the organs just mentioned." 1
These experiments seem entirely conclusive. In treat-
ing of the reflex phenomena of deglutition and their rela-
tions to the superior branches of the pneumogastric, the
pharyngeal, and the superior laryngeal, it will be seen that
irritation, either of these nerves or of the mucous membranes
to which they are distributed, will produce contractions in
the muscles. All who are practically familiar with the ap-
plication of electricity to the nerves know how difficult it is
to insulate the nervous trunks so as to avoid the influence
of "derived" currents. In carefully studying the experi-
ments of Longet, it seems that all the physiological condi-
tions were fulfilled ; and that when the nerve is divided at the
root and the stimulation is applied to the peripheral end, so
as to cut oif all reflex action from the nervous centres, and
when sufficient care is exercised to prevent the propagation
of the current to the motor connections of the pneumogas-
tric, the nerve, from its origin at the medulla oblongata to
the ganglion of the root, contains no motor filaments, and
is therefore exclusively sensory.
Among the more recent experiments which have led to
the view that the roots of the pneumogastrics contain motor
filaments, are those of Chauveau, made in 1862, and of Yan
Kempeu, published in 1863. In the experiments of Chau-
veau, the excitation was applied to the roots of the nerves
in animals just killed, with the effect of producing energetic
contractions of the oesophagus and stomach. The roots,
however, were not divided.2 It is stated in this article that
all reflex action ceases in adult mammals with the move-
1 LOXGET, Trait'e de physiologic, Paris, 1869, tome iii., p. 508.
2 CHAUVEAU, Du nerf pneumogastrique, etc. — Journal de la physiologie, Paris,
1862, tome v., p. 198.
2 1C) . NERVOUS SYSTEM.
ments of the heart.1 This assumption is too broad ; and
certainly it would not have been less accurate, and would
have answered a vital objection, if the nerve had been di-
vided and galvanization had been applied to its peripheral
extremity ; for it is well known that so long as the motor
nerves and the muscles retain their irritability, contractions
will follow their stimulation after they have been separated
from the centres. In the experiments just cited, there is
every reason to believe that the contractions of the oesoph-
agus and stomach were purely reflex. The remarks just
made concerning the experiments of Chauveau are equally
applicable to those of Yan Kempen, in which it is not stated
that the roots were divided ; 2 and, as far as we know, there
are no direct observations showing contraction of muscular
tissue following stimulation of the roots of the pneumogas-
trics, which cannot be explained by the principle of reflex
action, or by the supposition that the stimulation was ex-
tended to communicating motor filaments. In view of these
facts, we do not consider it necessary to discuss the question
more fully in detail, and will adopt, without reserve, the
conclusions of Longet, that the true filaments of origin of
the pneumogastrics are exclusively sensory, or, at least, that
they have no motor properties.
Properties and Functions of the Auricular Nerves. —
There is very little to be said with regard to the auricular
nerves, after the description we have given of their anat-
omy. They are sometimes described with the facial and
sometimes with the pneumogastric. They contain filaments
from the facial, the pneumogastric, and the glosso-pharyn-
geal. The sensory filaments of these nerves give sensibility
to the upper part of the external auditory meatus and the
membrana tympani.
1 CHAUVEAU, Du nerf pneumogastrique, etc. — Journal ck la physiologic, Paris,
1862, tome v., p. 193.
2 VAN KEMPEN, Nouvelles recherche* sur la nature fonct'tonelle des racines du
nerf pneumogastrique et du nerf spinal. — Journal de la physiologic, Paris, 1863,
tome vi., p. 284, et seq.
PHAKYXGEAL, XERVES. 217
•
Properties and Functions of the Phciryngeal Nemes. —
The pharyngeal branches of the pneumogastric are mixed
nerves, their motor filaments being derived from the spinal
accessory. Their direct action upon the muscles of degluti-
tion belongs to the physiological history of the last-named
nerve. TTe have already stated, in treating of the spinal ac-
cessory, that the filaments of communication that go to the
pharyngeal branches of the pneumogastric are distributed to
the pharyngeal muscles.1
It is impossible to divide all of the pharyngeal filaments
in living animals and observe directly how far the general
sensibility of the pharynx and the reflex phenomena of deg-
lutition are influenced by this section. As far as we can
judge from the distribution of the filaments to the mucous
membrane, it would seem that they combine with the pha-
ryngeal filaments of the fifth, and possibly sensory filaments
from the glosso-pharyngeal, in giving general sensibility to
these parts.
In some recent experiments by Waller and Prevost, on
the reflex phenomena of deglutition, it is shown that the ac-
tion of the pharyngeal muscles cannot be excited by stimu-
lation of the mucous membrane of the supralaryngeal region
and the pharynx, after section of the fifth and the superior
laryngeal branch of the pneumogastrics.3 This would seem
to show that the pharyngeal branches of the pneumogastrics
are of little or no importance in these reflex phenomena.
Properties and Functions of the Superior Laryngeal
Nei^ues. — The distribution of these nerves points to a double
function ; viz., an action upon the crico-thyroid muscles, and
the important office of supplying general sensibility to the
upper part of the larynx and a portion of the surrounding
mucous membrane.
1 See page 1 To.
2 WALLER ET PRETOST, fitude relative crux nerfs semitifs qui president aiiz
pherwmenes reflexes de la deglutition. — Archives de physiologic, Paris, 1870, tome
UL, p. 347.
218 NERVOUS SYSTEM.
•
The stimulation of these nerves produces intense pain
and contraction of the crico-thyroids ; but it has been shown
by experiment that the arytenoid muscles, through which
the nerves pass, receive no motor filaments.1
The action of the nerves upon the muscles is very sim-
ple, and resolves itself into the function of the crico-thyroids,
which has been treated of fully under the head of phona-
tion.3 When these muscles are paralyzed, the voice be-
comes hoarse. The filaments to the inferior muscles of the
pharynx are few and comparatively unimportant. It is im-
portant in this connection to note that the superior laryn-
geals do not receive their motor filaments from the spinal
accessory.
The sensory filaments of the superior laryngeals have
Important functions connected with the protection of the
air-passages from the entrance of foreign matters, particu-
larly in deglutition, and are further concerned, as we shall
see, in the reflex action of the constrictors of the pharynx.
In treating of deglutition, in another volume, we have fully
discussed the importance of the exquisite sensibility of the
top of the larynx in the protection of the air-passages.
When both superior laryngeals have been divided in living
animals, liquids often pass into the larynx in small quantity,
owing to the absence of the reflex closure of the glottis
when foreign matters are brought in contact with its supe-
rior surface, and the occasional occurrence of inspiration
during deglutition.3
Aside from the protection of the air-passages, the supe-
rior laryngeal is one of the sensory nerves through which
the reflex acts in deglutition operate. There are certain parts
which depend for their sensibility entirely upon this nerve ;
viz., the mucous membrane of the epiglottis, the aryteno-epi-
glottidean fold, and the larynx, as far down as the true vocal
cords. When an impression is made upon these parts, as
1 LONGET, Traite de physiologic, Paris, 1869, tome Hi., p. 525.
2 See vol. iii., Voice and Speech, p. 495. z See vol. ii., Digestion, p. 19V.
SUPERIOR XARYNGEAL SERVES. 219
when they are touched with a piece of meat, regular and
natural movements of deglutition ensue. In the recent and
elaborate experiments of Waller and Prevost, it was shown
that, after division of the superior laryngeals, excitation of
the parts supplied with sensory filaments by these nerves
produced no movements of the pharynx.1
The experiments made by galvanizing the trunks of the
nerves are extremely interesting. If the nerves be divided
and galvanization be applied to their central ends, move-
ments of deglutition are observed, and there is also arrest
of the action of the diaphragm. From these experiments,
first elaborated by Rosenthal,3 it would seem that the im-
pression which gives rise to the movements of deglutition
aids in protecting the air-passages from the entrance of for-
eign matters, by temporarily arresting the inspiratory act.
These experiments of Rosenthal have been repeated very
extensively by physiologists ; and concerning the effects of
galvanization of the superior laryngeals upon respiration,
there is considerable difference of opinion.
The important point for our consideration, in this con-
nection, is the action of the nerves in the ordinary phe-
nomena of deglutition ; and in experiments with galvanism,
a feeble current simulates most nearly the natural pro-
cesses. In such experiments, the results have been quite
satisfactory. Waller and Prevost used a very feeble current,
and confirmed entirely the observations of Hosenthal. They
found, also, that galvanization of the roots of the pneumo-
gastrics above the origin of the laryngeals produced the same
effects as galvanization of the trunks of the superior laryn-
geals.3 The experiments in which a powerful current of
1 WALLER ET PREYOST, op. cit. — Archives de physiologic, Paris, 1870, tome
iii., p. 347, el seq.
9 ROSESTHAL, De ^influence du nerf pneumogastrique el du nerf larynge supe-
rieur sur Ics mouvements du diaphragm. — Comptes rendus, Paris, 1861, tome Hi.,
p. 754 ; and, Die Athembewegungen und ihre Beziehungen zum Nerous vagu?, Ber-
lin, 1862, S. 72.
8 Loc. cit.
220 NEKVOUS SYSTEM.
galvanism was applied to the nerves also show an arrest of
respiration ; but it is argued that there is nothing special in
the action of the superior laryngeals under these conditions,
inasmuch as other sensitive nerves have been found to act
in the same way.1 This is undoubtedly true ; but it is well
known that, in living animals, strong impressions made upon
any of the acutely sensitive nerves arrest respiration, and
that this is one of the phenomena commonly observed in
animals struggling under painful operations. In view of
these facts, it seems unnecessary to discuss more fully the
numerous experiments on the effects upon respiration of
stimulation of the superior laryngeals ; and we can assume
that it has been demonstrated that an impression made -upon
the terminal filaments of these nerves, such as occurs in the
ordinary process of deglutition, excites, by reflex action, con-
traction of the constrictors of the pharynx, and, at the same
time, momentarily suspends the movements of the diaphragm.
Important experiments have been made within the past
few years, upon the action of the pneumogastrics on the cir-
culation, in which it is claimed that nervous filaments, arising,
in the rabbit, in part from the trunk of the pneumogastric
and in part from the superior laryngeal branch, act as reflex
depressors of the vascular tension. These experiments will
be fully discussed in connection with the cardiac branches.
Properties and Functions of the Inferior, or Recurrent
Laryngeal Nerves. — The anatomical distribution of these
nerves shows that their most important function is con-
nected with the muscles of the larynx. The few filaments
which are given off in the neck to join the cardiac branches
are probably not very important. It is proper to note, how-
ever, that it supplies the musculai tissue and mucous mem-
brane of the upper part of the oesophagus and the trachea, and
one or two branches are sent to the inferior constrictor of
1 BERT, Le$ons sur la physiologic comparee de la respiration, Paris, 1870, p.
459, et seq.
RECURRENT LARYXGEAL NERVES. 221
the pharynx. The function of these filaments is sufficiently
evident.
The inferior laryngeals contain chiefly motor filaments,
judging from their distribution as well as from the effects
of direct irritation. All who have experimented upon these
nerves have noted little or no evidence of pain when they
are stimulated or divided.
One of the most important functions of the recu'rrents is
connected with the production of vocal sounds. In another
volume, we have fully treated of th'e mechanism of the voice
and the action of the intrinsic muscles of the larynx ; 1 and
in our account of the physiology of the internal, or com-
municating branch from the spinal accessory to the pneu-
mogastric, it has been shown that this is the true nerve of
phonation.8 In the older works upon physiology, before the
functions of the spinal accessory were fully understood, the
experiments on the inferior laryngeals led to the opinion
that these were the nerves ol phonation, as they showed loss
of voice following their division in living animals. It is
true that these nerves contain the filaments which preside
over the vocal movements of the larynx ; but it is also the
fact that these vocal filaments are derived exclusively from
the spinal accessory, and that the recurrents contain as well
motor filaments which preside over movements of the larynx
not concerned in the production of vocal sounds.
The muscles of the larynx concerned in phonation are,
the crico-thyroids, animated by the superior laryngeals, and
the arytencid, the lateral crico-arytenoids, and the thyro-
arytenoids, animated by the inferior laryngeals. The poste-
rior crico-arytenoids are respiratory muscles ; and it is curi-
ous that these are not affected by extirpation of the spinal
accessories, but that the glottis is still capable of dilatation,
so that inspiration is not -impeded. If, however, the spinal
accessories be extirpated, and the larynx be then exposed
in a living animal, the glottis still remains dilated, but will
1 See vol. ill, Voice and Speech, p. 490, et seq. 8 See page 170, et sey.
222 NEKVOTTS SYSTEM.
not close when irritated. If the inferior laryngeals be then
divided, the glottis is mechanically closed with the inspira-
tory act, and the animals often die of suffocation. When we
sCall to mind the varied sources from which the pneumogas-
trics receive their motor filaments, it is easy to understand
how certain of these may preside over the vocal movements,
and others, from a different source, may animate the respira-
tory movements.
As we should naturally expect from what has already
been said, section of the inferior laryngeal nerves paralyzes
both the vocal and the respiratory movements of the larynx.
It is not necessary to refer in detail to the ancient and mod-
ern experiments illustrating this point, the former dating
from the time of Galen. In adult animals, the cartilages of
the larynx are sufficiently rigid to allow of inspiration after
the organ has been completely paralyzed ; but in young ani-
mals, the glottis is closed, and suffocation ensues. "We have
generally observed in cats, that suffocation follows immedi-
ately upon section of the recurrents or of the pneumogastrics
in the neck.
The impediment to the entrance of air into the lungs is
a sufficient explanation of the increase in the number of the
respiratory acts after division of both recurrents. It has
been observed by Longet, that the acceleration of respiration
is much greater in young than in adult animals. This does
not apply to very young animals, in which section of the re-
currents produces almost instant death.1
Waller and Prevost have shown that feeble galvanization
of the central ends of the inferior laryngeals, after their di-
vision, produces rhythmical movements of deglutition, gen-
erally coincident with arrest of the action of the diaphragm.
These phenomena are generally observed in rabbits, but
they are not constant.3 The reflex action of these nerves in
1 LONGET, Tralte de physiologic, Paris, 1869, tome iii., p. 533.
2 WALLER ET PREVOST, Phenomenes reflexes de la deglutition. — Archives de
physiologic, Paris, 1870, tome iii., p. 346.
CARDIAC NERVES. 223
deglutition is probably due to the communicating filaments
which they send to the superior laryngeal nerves.
Properties and Functions of the Cardiac Nerves, and
Influence of the Pneumogastrics upon the Circulation. — One
of the most interesting questions connected with the physi-
ology of the pneumogastric nerves is their action upon the
heart ; and the results of experiments, which will be fully
detailed hereafter, are precisely the opposite of what would
be expected in the case of a nerve containing motor fila-
ments and distributed to a muscular organ. . Section of the
pneumogastrics in the neck, far from arresting the action of
the heart, increases the rapidity of its. pulsations; and gal-
vanization of the nerves arrests the heart's action in diastole.
TV"ithin the past few years, some very remarkable experi-
ments have been made upon the influence of certain nerves
given off near the superior laryngeals, which have been
called the depressors of the circulation ; but most observa-
tions have been made upon the trunks of the pneumogastrics
in the cervical region, as it is exceedingly difficult to isolate
the thoracic cardiac branches and to operate upon them with-
out involving other nervous filaments. In galvanizing the
nerves in the neck, we have to consider both the direct
influence of the current and the phenomena due to reflex
action.
Effects of Section of the Pneumogastrics upon the Circu-
lation.— It is not necessary to cite in detail the various ex-
periments upon the effects of section of the pneumogastrics
in the neck upon the action of the heart. The division of
these nerves in living animals is sufficiently easy, and all
who have performed the operation have noted the same re-
sults. By section of these nerves, the heart is at once sepa-
rated from one of the most important of its nervous connec-
tions ; and the effects show that, as far as this organ is con-
cerned, the motor filaments present great differences from
115
NEKVOUS SYSTEM.
the ordinary motor nerves of the cerebro-spinal system.
Most of the observations made by dividing the nerves have
been upon dogs, and the differences in the effects upon other
animals are slight and unimportant. The following are the
important phenomena presented in typical experiments :
Section of one of the pneumogastrics in the neck does
not produce any very marked effect upon the action of the
heart, after the slight disturbance which usually follows the
operation has passed away. The number of pulsations is
slightly increased, and the cardiac pressure, as shown by a
cardiometer fixed in the carotid artery, is slightly dimin-
ished ; but this is insignificant compared with the effects of
dividing both nerves.
Section of both pneumogastrics usually produces imme-
diate and serious disturbance in the respirations, which are
momentarily accelerated. The animal usually becomes agi-
tated and suffers from want of air ; and, when it is desired
especially to note the cardiac disturbance, it is often neceS'
sary to relieve the respiration by introducing a tube into the
trachea. In full-grown dogs, however, the respirations soon
become calm, but are diminished in frequency, and are un-
usually profound. "When the animal is in this condition,
the beats of the heart are very much increased in frequency.
at least doubled ; but they are inefficient and tremulous.
An interesting point in this connection is the want of in-
fluence of certain medicinal substances over the action of the
heart in animals after division of the pneumogastrics. Traube
has shown that, while digitalis injected into the veins of a
dog was capable in an hour of reducing the pulse to about
one-fourth of the normal number of beats per minute, there
was no appreciable effect upon the circulation when the
injection was made in animals with both pneumogastrics
divided.1
The influence of the pneumogastrics upon the heart is
1 TRAUBE, Versuche uber die WirTcung dcr Digitalis. — Gesammelte Beitrage zur
Pathologic und Physiologic, Berlin, 1871, Bd. i., S. 190, et seg.
CARDIAC NEKVES. 225
one of the most interesting points in the physiology of the
circulation ; tut we can discuss the mechanism of the phe-
nomena following section of the nerves more satisfactorily
after we have considered the effects of their galvanization.
Effects of Galvanizing the Pneumogastrics or tJielr
Branches upon the Circulation. — The experiments upon the
effects of galvanization of the pneumogastrics in the neck
on the action of the heart are almost innumerable ; and, al-
though the explanations of the phenomena observed present
the widest differences, the facts themselves are sufficiently
simple. These facts will be discussed under the following
heads : 1. The direct influence of galvanization of the nerves
in the neck, undivided, or of galvanization of the peripheral
extremities of the trunks after division. 2. Reflex phenom-
ena following galvanization of the central ends of branches
of the pneumogastrics, after their division.
Direct Influence of the Pneumogastrics on the Heart. —
In 1846, the brothers Weber noted the important fact that
galvanization of the pneumogastrics in the neck rendered
the action of the heart slow, and if the galvanization were
sufficiently powerful, arrested the heart, which remained
flaccid and in diastole for a certain time while the galvaniza-
tion was continued.1 This fact has since been confirmed by
numerous experimenters, whose observations, however, will
not be cited in detail, except as they have developed new
and important phenomena.
TVhile there is no difference of opinion among physiolo-
gists with regard to the stoppage of the heart by power-
ful galvanization, it is stated by some that a very feeble
current passed through the peripheral ends of the divided
nerves quickens the heart's action ; but it is admitted by all
that it is very difficult to regulate the intensity of the cur-
1 \VEBER, in WAGXER, Handworterbuch der Physiologie, Braunschweig, 1846,
Bd. iii., Zweite Abtheilung, S. 42, et seq.
226 NEKVOUS SYSTEM.
rent so as to produce this effect. After section of the nerves,
the action of the heart is very readily modified by struggles,
etc., on the part of the animal under observation ; and, in
view of the exceeding nicety of the reported experiments,
it cannot be admitted that the heart is capable of being ex-
cited to increased rapidity of action, without observations
of the most positive character. Such facts are wanting;
and furthermore, it has been shown by Dr. Rutherford, in a
series of exceedingly exact and satisfactory experiments, that
whenever a galvanic current passed through the pneumo-
gastrics has any appreciable effect upon the action of the heart,
it is to diminish the frequency of its pulsations.1 Inasmuch
as our object is simply to show that, imitating the nervous
force by galvanism, the action of the pneumogastrics is in-
hibitory, we will not discuss the effects of different currents,
and other experiments, which have little relation to the
natural action of the nerves, and possess slight interest from
a purely physiological point of view.
The direct action of the pneumogastrics upon the heart
is undoubtedly through their motor filaments. All the facts
developed by experiments are in accordance with this view.
If the nerves be divided in the neck, galvanization of the
central ends has no effect upon the heart, the pulsations
being arrested only when the peripheral ends are stimulated.
This shows that, at least as far as the fibres passing down
the neck are concerned, the action is centrifugal and di-
rect, not reflex. Another curious fact illustrates the same
point very forcibly. It is well known that the woorara-
poison completely paralyzes the motor nerves, leaving the
muscular irritability and the sensory nerves intact. It has
been found that, in animals poisoned with woorara, the action
}f the heart being maintained by artificial respiration, gal-
vanization of both pneumogastrics has no effect upon its
1 RUTHERFORD, Influence of the Vagus upon the Vascular System. — Journal
of Anatomy and Physiology, Cambridge and London, 1869, vol. iii., p. 404,
CARDIAC NERVES. 227
pulsations.1 This fact we have repeatedly verified in public
demonstrations.3 Still another curious fact remains bearing
on the question under consideration. If powerful galvani-
zation, which immediately arrests the cardiac pulsations, be
continued for a certain time, so that the motor filaments
become temporarily exhausted and lose their irritability, the
heart resumes its contractions, notwithstanding that the
galvanization is continued ; the nerves being for the time
incapable of transmitting the inhibitory influence.3
The source of the motor filaments in the pneumogastrics
which exert a direct inhibitory action upon the heart be-
comes an important point to determine. In the original
experiments by the brothers Weber, it was shown that, when
the galvanic stimulus was applied to that portion of the
centres from which the nerves take their origin, the action
of the heart was arrested in the same way as when the nerves
themselves are galvanized ; 4 and it has been shown by sub-
sequent observations, that when the heart is thuss arrested
by galvanization of the medulla oblongata, if both pneumo-
gastrics be divided in the neck, its action is resumed.5 This
would at first sight lead to the supposition that the inhibi-
tory filaments are derived from the roots themselves of the
1 BERNARD, Lemons sur les effete des substances toxiques et medicamenteuses,
Paris, 1857, p. 348.
2 In the inferior classes of animals, there are some exceptional phenomena
with regard to the pneumogastrics. In experiments made upon alligators, in
Xew Orleans, in 1861, we found that the action of the heart was promptly ar-
rested by galvanizing the nerves in the neck, when the animal was killed and
the general motor nerves were paralyzed by woorara. In some additional ex-
periments, we showed that all of the nerves were not affected by the poison after
the same length of time, and that the pneumogastrics were probably the last to
come under its influence. (See vol. i., Circulation, 1866, p. 234.) Bernard states,
also, that galvanization of the nerves in birds does not affect the heart, a fact
for which he offers no explanation. (BERNARD, Systeme nervevx, Paris, 1858,
tome ii., p. 394.)
3 LONGET, Traite de physiologic, Paris, 1869, tome ii., p. 117.
4 WEBER, in WAGNER, Handworterbuch der Physiologic, Braunschweig, 1846,
Bd. in., Zweite Abtheilung, S. 42.
5 LONGET, Traite de phy&iologie, Paris, 1869, tome ii., p. 117.
228 NERVOUS SYSTEM.
pneumogastrics ; but it has been conclusively demonstrated
that they -are really derived from the spinal accessories, the
upper filaments of origin of which are situated just below
the roots of the pneumogastrics.
The action of the spinal accessories upon the heart has
already been considered.1 The connection between these
nerves and their influence over the heart may be briefly
repeated, as follows :
It has been shown that powerful galvanization of one
pneumogastric will arrest the heart's action. "Waller, after
extirpating the spinal accessory nerve upon one side, found
that galvanization of the pneumogastric upon that side had
no effect upon the heart, provided that from ten to twelve
days had elapsed after extirpation of the spinal accessory,
a sufficient time to secure disorganization and loss of irrita-
bility of its fibres. These experiments show conclusively
that the motor filaments contained in the pneumogastric,
which act directly upon the heart, are derived exclusively
from the communicating branch of the spinal accessory.
Reflex Influence, through the Pneumogastrics^ upon tlie
Circulation. — Galvanization of the central ends of the pneu-
mogastrics, after their division in the neck, does not influ-
ence the action of the heart, except as the pulsations are
affected by the modifications in respiration. In experiments
made upon this point by Bernard, the difference in the ef-
fects of galvanization of the central and the peripheral ends
was distinctly noted. When the central ends were stimu-
lated in dogs, the pupils became dilated, the eyes protruded,
sometimes vomiting occurred, and always the number of
respiratory acts was diminished, and, with a powerful cur-
rent, were arrested in inspiration ; but the pulsations of the
heart were not affected.3
1 See p. 204.
2 BERNARD, Systems nerveux, Paris, 1858, tome ii., p. 382, et seq.
The arrest of respiration, particularly the action of the diaphnagm, was first
DEPRESSOR-NERVE. 229
Depivssor-Newe. — An important reflex action operating
upon the circulation through branches of the pneumogastrics
has lately been described by Cyon and Ludwig, in a memoir
which received the prize for Experimental Physiology from
the French Academy of Sciences, in 1867.1 The experi-
ments on which this memoir is based are exceedingly clear
and satisfactory, and afford, perhaps, the only positive expla-
nation we have of reflex action upon the heart. 'The sub-
stance of these observations is briefly as follows : 2
In the rabbit is a nerve arising by two roots, one coming
from the trunk of the pneumogastric and the other from its
superior laryngeal branch, passing then toward the carotid
artery and taking its course down the neck by the side of
the sympathetic as far as the thorax. " In the chest, it joins
with sympathetic filaments to pass with them to the heart,
by little branches between the origin of the aorta and the
pulmonary artery.
This nerve can be completely isolated in the neck from
the sympathetic and the trunk of the pneumogastric. If it
be divided m this situation, after the irritation produced
by the operation has subsided, very distinct and important
modifications in the circulation may be produced by its gal-
vanization.
In the first place, it was noted in all the experiments,
that galvanization of the peripheral extremities produced no
change, either in the number of the pulsations of the heart
or in the pressure of blood in the vascular system ; which
noted by Traube. (TRAUBE, Zur Physiologic des Nervus vagus. — Gesammdte
Bdtrdge, Berlin, 1871, Bd. L, S. 184.)
1 BERNARD, Rapport sur un memoire de M. E. CYOX, intitule : de V action re-
flexe d>un des nerfs sensibles du cceur. — Journal de Tanatomie, Paris, 1868, tome
v., p. 337.
2 CYON ET LUDTTIG, Action reflexe d"*un des nerfs sensibles du cceur sur les
nerfs vaso-moteurs. — Journal de V anatomic, Paris, 1867, tome iv., p. 472, et scg.
Cyon has lately found in the horse, nerves, in their anatomical and physio-
logical relations, closely resembling the "depressor-nerves" which he first de-
scribed in the rabbit (British and Foreign Medico- Chirurgical Review, London,
1871, Xo. xcvi., p. 540).
230 NERVOUS SYSTEM.
points to the fact that its action is not direct, but reflex, and
is due to an impression conveyed to the nerve-centres.
If the central ends of the nerves be galvanized, the press-
ure in the arteries diminishes little by little, until it may be
reduced to one-half or two-thirds of the pressure before the
irritation was applied. This low pressure continues so long
as the interrupted current is applied ; but when the galvani-
zation is arrested, it gradually returns to the normal stand-
ard. These phenomena are observed in all the large arterial
trunks. The length of time required to produce the great-
est diminution in the pressure is somewhat variable, but the
experimenters have never seen it reach its minimum before
fifteen pulsations of the heart.
" The diminution in the pressure is attended with a re-
duction of the pulse in the instances in which the depressor-
nerve only has been divided. The irritated nerve is isolated
in a manner so complete that we cannot fear the passage of
the exciting current in the trunk of the pneumogastric. The
changes in the number of pulsations persist even when the
pneumogastric has been excited by the side where the irri-
tation has been applied, from the point where the superior
laryngeal is given off to the point where the pneumogas-
tric enters the thoracic cavity.
" From the foregoing it is evident that the changes tak-
ing place in the number of pulsations are due to excitation
of the depressor-nerve. If we study attentively the progress
of the cardiac pulsations during the excitation, we observe
always that the most considerable reduction takes place at
the beginning of the experiment ; that is to say, at the
moment when the blood-pressure descends from its normal
standard to the lowest point. When the pressure is com-
pletely depressed, the pulse is accelerated again and even
reaches almost completely the numbers presented before the
oscillations. "When the irritation ceases, after a shorter
or longer period, the heart generally beats more rapidly
than before the irritation, and this during all the time that
DEPBESSOK-NERVE. 231
is occupied in the return of the pressure to the normal stand-
ard. This observation in itself refutes the idea that the
diminution in the pressure may depend upon the diminished
number of pulsations. If the reduction in the rate of the
pulse produced a diminished pressure, it should be increased
when the pulsations of the heart become accelerated.
" The manner in which the pulse is reduced leads to the
supposition that it is due to a reflex action of the pneunao-
gastric.
"It was easy to verify this last opinion, and we have
been able to confirm it by first cutting the pneumogastrics
on both sides, and afterward irritating the central end of the
depressor-nerve. In this case, the pressure fell to 0.62, 0.55,
etc., while the number of pulsations remained the same, or
at least oscillated very slightly above and below the number
observed before the irritation."
The above extract from the observations of Cyqn shows
two important points :
First, galvanic stimulation of the central extremities of
the divided depressor-nerves reduces the number of pulsa-
tions of the heart by a reflex action ; the impression being
conveyed to the nerve-centres by the depressor-nerves, the
force acting directly upon the heart being transmitted through
efferent filaments in the trunk of the pneumogastric.
Second, the reduction in the pressure of blood in the
larger arteries is independent of the efferent filaments of the
pneumogastric, and bears no relation to the reduction in the
number of cardiac pulsations.
It now remains to explain, if possible, the mechanism of
the reduction in the arterial pressure. This question is
treated by Cyon by the method of exclusion. The diminu-
tion in the pressure followed galvanization of the central ex-
tremities of the depressor-nerves, even when the heart was
removed from its influence by section of both pneumogas-
trics in the neck, and when all the voluntary movements
and the movements of respiration were abolished by poison-
232 NERVOUS SYSTEM.
ing with woorara. In the latter case, the circulation was
kept up by artificial respiration.
Without following out the various observations which go
to show that the influence of the depressor-nerve upon the
arterial pressure is independent of the force or frequency of
the heart's action, and is due to some cause which operates
upon the vessels themselves, we will simply give the results
of the experiments upon the splanchnic nerves. If the abdo-
men be opened, and one or more of these nerves be divided,
the arterial pressure is immediately diminished. After this,
if the peripheral extremities of the divided nerves be galvan-
ized, the pressure rapidly returns to the normal standard.
These experiments " demonstrate that the splanchnic nerves
constitute the most important vaso-motor nerves in the en-
tire organism."
This point being settled, the depressor-nerves were gal-
vanized after section of the splanchnic nerves, in some cases
exaggerating the general arterial pressure by compressing
the aorta, and in others, leaving the aorta free. " The irrita-
tion of the depressor-nerve after section of the splanchnic
nerve produced still a diminution in the blood-pressure, but
the absolute value of this diminution is much less than it was
during the irritation of the depressor-nerve before the sec
tion of the splanchnic."
These experiments show pretty conclusively that the di-
minished pressure in the arterial system following stimula-
tion of the central ends of the depressor-nerves after division
is due to a reflex action on the blood-vessels of the abdomi-
nal organs, taking place through the splanchnic nerves. We
are sufficiently familiar with reflex paralyzing action upon
the blood-vessels through the sympathetic system ; and when
we call to mind the immense extent of the abdominal vascu-
lar system, we can readily understand how, if the resistance
to the flow of blood be diminished by paralysis of the mus-
cular coats of the small arteries, the pressure in the larger
arteries would be reduced.
PULMONARY NERVES.
^Lechanism of the Influence of the Pneumogastrics upon
the Action of the Heart. — It is useless to speculate upon the
exact mechanism of the action of the pneumogastrics upon
the heart. Although various explanations have been pre-
sented of the effects following division of the nerves in the
neck, and of the opposite phenomena which attend the gal-
vanization of their peripheral ends, they are all more or less
unsatisfactory. All that can be said, in the present state of
our knowledge, is, that the pneumogastrics have a direct in-
hibitory influence on the heart. When they are divided,
and the heart is removed from their influence, the pulsations
become more rapid. When the peripheral ends of the di-
vided nerves are galvanized, the heart beats more slowly, or^
its action may be arrested by .a current of sufficient power.
This action may also be reflex, due to an impression con-
veyed to the centres by what have been described by the
brothers Cyon and Ludwig, as the depressor-nerves.
Properties and Functions of the Pulmonary Branches,
and Influence of the Pneumogastrics iipon Respiration.
— The trachea, bronchi, and the pulmonary structure are
supplied with motor and sensory filaments by branches of
the pneumogastrics. The recurrent laryngeals supply the
upper, and the pulmonary branches, the lower part of the
trachea, the lungs themselves being supplied by the pulmo-
nary branches alone. The sensibility of the mucous mem-
brane of the trachea and bronchi is due to the pneumogas-
trics, for these parts are insensible to irritation when the
nerves have been divided in the neck. Longet has shown
that, while an animal coughed and showed signs of pain
when the mucous membrane of the respiratory passages was
irritated, after division of the pneumogastrics there was no
evidence of sensibility, even when the tracheal mucous mem-
brane was treated with strong acid, or even cauterized. He
also saw the muscular fibres of the small bronchial tubes
23-i NERVOUS SYSTEM.
contract wlien a galvanic stimulus was applied to the branches
of the pneumogastrics.1
The main interest, in this connection, is attached to the
pulmonary branches and their relations to the respiratory
acts. These are undoubtedly connected with important re-
flex phenomena, acting as centripetal nerves ; and their di-
rect action in respiration is probably much less important.
They are exposed and operated upon in living animals with
so much difficulty, that we know little of the direct effects
of their irritation, and must judge of their general properties
chiefly by experiments showing their action upon respira-
tion. We shall have to study, in connection with the func-
tions of these nerves, the effects of their division upon the
lungs and the respiratory acts, and the phenomena, referable
to the respiratory organs, which follow their galvanization.
We shall also consider certain theoretical views with regard
to their action in the automatic processes of respiration, and
with the sense of want of air (besoin de respirer], which gives
rise to the reflex respiratory acts.
Effects of Division of the Pneumogastrics upon Respira-
tion.— Section of both pneumogastrics in the neck, in mam-
mals and birds, is usually followed by death, in from two to
five days. In young animals, death may occur almost in-
stantly, from paralysis of the respiratory movements of the
glottis, a fact which we have already noted in connection
with the recurrent laryngeal nerves.8 In this connection, we
may note an interesting fact observed by Prof. J. C. Dalton,
of New York, who has succeeded in keeping dogs alive after
division of both pneumogastrics in the neck until complete
recovery took place. In several instances of this kind, after
killing the animals, Prof. Dalton found complete reunion of
the divided ends.8
Yery little of importance, with regard to the functions of
1 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 535.
9 See page 222. 3 Oral communication.
PULMONARY NEKVES. 235
the pneumogastrics in connection with respiration, has been
ascertained by the numerous experiments on record of sec-
tion of one or both of these nerves in the cervical region.
It has been found by all experimenters, that animals survived,
and presented no very distinct abnormal phenomena, after
section of one nerve. Longet states that animals operated
upon in this way present hoarseness of the voice and a slight
increase in the number of respiratory acts. Some observers
have found the corresponding lung partly emphysematous
and partly engorged with blood, and others have not noted
any change in the pulmonary structure.1
When both nerves are divided in full-grown dogs, an ex-
periment which we have often repeated, the effect upon the
respiratory movements is very marked. For a few seconds,
the number of respiratory acts may be increased ; but as
soon as the animal becomes tranquil, the number is very
much diminished, and the movements change their charac-
ter. The inspiratory acts become unusually profound, and
are attended with excessive dilatation of the thorax. The
animal is generally quiet and indisposed to move. We have
seen, under these conditions, the number of respirations fall
from sixteen or eighteen to four per minute.
In most animals that die from section of both pneumo-
gastrics, the lungs are found engorged with blood, and, as it
were, carnified, so that they sink in water. This curious
fact was noted by Legallois ; 2 and although its physiological
significance is not apparent, it has been the subject of much
speculation and experimental research. Many attempts have
been made to account for this peculiar condition. Traube
supposed that it was due to the penetration of secretions
into the respiratory passages ; 3 but this was disproved by
1 LONGET, Anatomie et physiologic du systeme nerveux, Paris, 1842, tome ii.,
p. 349, et seq.
MAGEXDIE, Phenomenes physiques de la vie, Paris, 1842, tome i., p. 204.
2 LEGALLOIS, (Euvres, Paris, 1824, tome i., p. 194.
3 TRACBE, Die Ursachen und die Bes$haffenheit derjenigen Veranderungen,
236 NEKVOUS SYSTEM.
Bernard, who has presented by far the most satisfactory
explanation of this condition.
Bernard found that the pulmonary lesion did not exist
in birds, although section of both nerves was fatal. It had
previously been ascertained that, in some animals, death
takes place with no alteration of the lungs.1 "When the en-
trance of the secretions into the air-passages was prevented
by the introduction of a canula into the trachea, the carni-
fication of the lungs was nevertheless observed. "Without
detailing all of the experiments upon which the explanation
offered by Bernard is based, it is sufficient to state that he
observed a traumatic emphysema as a consequence of the
excessively labored and profound inspirations. Indeed, this
can be actually seen when the pleura is exposed in living
animals. As a result of this distention of the air-cells, the
pulmonary capillaries are ruptured in different parts, the
blood becomes coagulated, and the lungs are finally carni-
fied. This .cannot occur in birds, because the lungs are fixed,
and their relations are such that they are not exposed to ex-
cessive distention in inspiration. a
There is no satisfactoiy explanation of the remarkable
changes in the respiratory movements that follow section of
the pneumogastrics.
Sense of Want of Air. — The pneumogastrics may regu-
late the respiratory acts, but they are not the medium
through which the sense of want of air (besoin de respirer\
which gives rise to the reflex movements of respiration, is
conveyed to the nerve-centres. If it be true, as it undoubt-
edly is, that section of both pneumogastrics in the neck
modifies the number and the character of the respirations,
and that, after division of the nerves, galvanization of their
central ends arrests respiration, it is more than probable
welche das Lungenparenchym nach Durchschneidung der Ner. vagi erleidet. —
Gesammelte Beitrage zur Paihologie und Physiologic, Berlin, 1871, Bd. i., S. 80.
1 BERNARD, Systeme nerveux, Paris, 1858, tome ii., p. 353.
8 BERNARD, op. tit., p. 368.
PULMONARY NEKVES. 237
that tliis function is normally influenced through these nerves,
by impressions conveyed to the centres ; but precisely what
this influence is, or what is the mechanism of its action, we
do not know.
The positive statement that the sense of want of air is
not conveyed to the nerve-centres through the pneumogas-
trics is based, to a great extent, upon our own experiments,
which have been fully detailed in another volume,-1 and we
will here give simply their results and the conclusions to
which they lead.
The acts of respiration are involuntary, though they may
be modified, within certain limits, through the will ; and
they are reflex, due to an impression conveyed to the re-
spiratory nervous centre, the medulla oblongata, which gives
rise to the stimulus that excites the action of the inspira-
tory muscles. It has been conclusively shown by experi-
ments, the first being those of Robert Hook,3 that if artifi-
cial respiration be efficiently carried on in a living animal,
so as to supply air fully to the system, the sense of want of
air is not appreciated, and the animal makes no effort to
breathe; but if respiration be imperfectly performed, the
animal almost immediately feels the want of air, and, in our
experiments, the exposed respiratory muscles were thrown
into violent but ineffectual contraction.
The principal points with reference to the location of the
sense of want of air and its transmission to the nerve-centres,
developed by our own experiments, are the following :
A dog was etherized, the chest was opened, exposing the
heart and lungs, and artificial respiration was carried on by
means of a bellows secured in the trachea. So long as the
supply of air was sufficient, the animal made no effort to
breathe, even when allowed to come from under the influ-
ence of the anaesthetic.
1 See vol. i., Respiration, p. 479, et scq.
2 An Account of an Experiment made by Mr. Hook, of Preserving Animals
alive by Blowing through their Lungs vrith BeUows. — Philosophical Transactions,
London, 1667, voL ii., p. 539.
238 NERVOUS SYSTEM.
An artery was then exposed and the color of the blood
noted. "When the artificial respiration was arrested, the
animal made efforts to breathe as soon as the blood became
dark in the arterial system. "We concluded from this, that
the impression conveyed to the respiratory nervous centre,
giving rise to the movements of respiration, was due to the
action of the non-oxygenated blood.
To ascertain whether the impression were made upon
the nerves distributed to the lungs or upon other nerves,
a large vessel was divided and the system was drained of
blood, the lungs being continually supplied with fresh air.
In this case, respiratory efforts of the most- violent character
were invariably noted following the haemorrhage. This por-
tion of the experiment demonstrated that the sense of want
of air was not dependent upon the accumulation of carbonic
acid in the lungs, but was due to a deficient supply of the
oxygen-carrying fluid to the general system. It further
demonstrated that the impression in the general system was
not due to the presence of carbonic acid, but to the absence
of oxygen ; for no blood containing carbonic acid circulated
in the system.
These phenomena were observed without any modifica-
tion, after division of both pneumogastric nerves in the neck,
and they seem to prove conclusively that the sense of want
of air is not transmitted to the respiratory nervous centre
through the medium of these nerves.1
Effects of Galvanization of the Pneumogastrics upon
Respiration. — The phenomena which follow galvanization
of the pneumogastrics, though they are curious and inter-
esting, do not throw much light upon the relations of these
1 For a full account of these experiments, with their bearing upon certain
respiratory phenomena before birth, the reader is referred to the original article,
entitled, Experimental Researches on Points connected with the Action of the Heart
and with Respiration, published in the American Journal of the Medical Sciences,
Philadelphia, October, 1861. Since this publication, the experiments have been
frequently repeated in public demonstrations, and the conclusions verified.
PULMONARY SERVES. 239
nerves to respiration. We have already mentioned the ar-
rest of the respiratory movements by galvanization of the
superior laryngeal branches and of the central ends of the
nerves after their division in the neck.1 The main point
of interest in this connection is the fact that the effects
observed are entirely reflex, galvanization of the peripheral
ends of the divided nerves having no direct action on the
movements of the thorax.
In view of the very indefinite physiological applications
of the experiments made by galvanizing the nerves, we will
not give in detail the numerous observations upon this sub-
ject, but simply state the results, as given in a recent and
very elaborate work on respiration, by M. Bert : 2
" 1. Respiration may be arrested by excitation of the
pneumogastrics (Traube), of the larynx (Cl. Bernard), of
the nostrils (M. Schiff ), of most of the sensory nerves (M.
Schiff, an assertion that I have not been able to verify).
" 2. This arrest may take place eith,er in inspiration or in
expiration, through any one of these nerves, without attrib-
uting it to the action of derived currents.
" 3. A feeble excitation accelerates the respiration ; a
more powerful excitation retards it ; a very powerful excita-
tion arrests it. These words £ feeble ' and i powerful ' hav-
ing, it is understood, only a relative sense for any one animal
and under certain conditions : what is feeble for one would
be powerful for another, etc.
"I believe, in opposition to the opinion of Eosenthal,
that section of the pneumogastrics does not increase the
difficulty of arresting respiration ; at least, death by ex-
citation occurs much more easily in this case.
"•±. When the respiratory movements are completely
arrested, it is always the same for the general movements
of the animal, which remains motionless.
1 See page 219.
9 BERT, Lemons sur la physiologie comparee de la respiration, Paris, 1870, p.
489, et seq.
116
240 NERVOUS SYSTEM.
" 5. Respiration returns even during excitation, and
when this is arrested, it almost always becomes accelerated.
"6. Arrest in expiration is more easily obtained than
arrest in inspiration ; there are animals, indeed, in which it
is impossible to effect the latter.
" 7. If an excitation be employed sufficiently powerful
to arrest respiration in inspiration, all -respiratory move-
ments may be made to cease at the very moment when the
excitation is applied (inspiration, half-inspiration, expira-
tion), either by operating on the pneumogastric, or oper-
ating upon the laryngeal. . . .
"Any feeble excitation of centripetal nerves increases
the number of the respiratory movements ; any powerful
excitation diminishes them. A powerful excitation of the
pneumogastrics, of the superior laryngeal, of the nasal
branch of the infra-orbital, may arrest them completely ;
if the excitation be sufficiently energetic, the arrest takes
place at the very moment it is applied. Finally, sudden
death of the animal may follow a too powerful impression,
thus transmitted to the respiratory centre : all this being
true for certain mammalia, birds, and reptiles."
The above formulated statements express the experimen-
tal facts at present known w^ith regard to the influence
of the pneumogastrics upon respiration. The pulmonary
branches themselves are so deeply situated that they have
not as yet been made the subject of direct experiment, with
any positive and satisfactory results. A theory has recently
been proposed in which it has been assumed that there are
two kinds of nerves in the pulmonary branches of the pneu-
mogastrics, one set being excited by inflation of the lungs,
which excitation gives rise to expiration, the other set being
stimulated by collapse of the lungs, which excites inspira-
tion ; but the experiments upon which this idea is based are
vague and unsatisfactory.1
1 HERING, Die Selbststeu rung der Athmimg durch den Nervus vagus. — Sitzungs-
•bericlite der mathematisch-naturuisscnschaftlichen Classe der k. Akademie der Wis*
mnschaften, Wien, 1868, Bd. Ivii., 2 Abtheilung, S. 672, et seq.
(ESOPHAGEAL NERVES. 241
Properties and Functions of the (Esophageal Nemes. —
The muscular walls and the mucous membrane of the oesoph-
agus are supplied entirely by branches from the pneumogas-
trics. The upper portion is supplied by filaments from the
inferior laryngeal branches, the middle portion, by filaments
from the posterior pulmonary branches, and the inferior
portion receives the oesophageal branches. These branches
are both sensory and motor ; but probably the motor fila-
ments largely predominate, for the mucous membrane,
though it is sensible to the extremes of heat and cold, the
feeling of distention, and a burning sensation upon the
application of strong irritants, is by no means acutely sen-
sitive.
That the movements of the oesophagus are animated by
branches from the pneumogastrics, has been clearly shown
by experiments. In the first place, except in animals in
which the anatomical distribution of the nerves is differ-
ent from the arrangement in the human subject, the entire
oesophagus is paralyzed by dividing the nerves in the neck.
In a series of very elaborate experiments, by Chauveau, it
was shown that section of the nerves in the cervical region
paralyzed the entire length of the oesophagus in rabbits, but,
owing to a peculiar distribution of the nerves in dogs, the
section paralyzed only the terminal portion.1
According to Bouchardat and Sandras,2 Longet, and oth-
ers, when the pneumogastrics are divided in the cervical
region, in dogs, if the animals attempt to swallow a consid-
erable quantity of food, the upper part of the oesophagus is
found enormously distended.3 Bernard noted, in a dog in
which a gastric fistula had been established, that articles of
food given to the animal did not pass into the stomach,
1 CHAUVEAF, Du nerf pneumogastrigue considere comme agent excitateur et
comme aye-it coordinateur dcs contractions cesophagiennes. — Journal de la physio-
logic, Paris, 1862, tome v., p. 342.
8 BOUCHARDAT ET SAXDRAS, Experiences snr Ics fonctions des nerfs pnewno-
gaslriques dans la digestion. — Comptes rendus, Paris, 1847, tome xxiv., p. 59.
3 LOXGET, Traite de physiologic, Paris, 1869, tome lit, p. 54T.
242 NEKVOUS SYSTEM.
though he made great efforts to swallow. An instant after
the attempt, the matters were vomited, mixed with mucus,
but of course did not come from the stomach.1
Direct experiments upon the roots of the pneumogastrics
have shown that these nerves influence the movements of
the oesophagus, and that their motor filaments are not de-
rived from the spinal accessory. Chauveau states, as the
result of numerous observations, that " the oesophagus con-
tracts throughout its entire length when the roots of the
pneumogastrics are excited ; — it never contracts when the
bulbar roots of the spinal accessory are excited.2
Properties and Functions of the Abdominal Brandies.
—In view of the very extensive distribution of the terminal
branches of the pneumogastrics to the abdominal organs, it
is evident that the functions of these nerves must be very
important, particularly since it has been shown that the
right nerve is distributed to the whole of the small intes-
tine. We shall consider the .functions of these branches in
their relations to the liver, the stomach, and the intestines.
"We have no positive information with regard to their action
upon the spleen, kidneys, and suprarenal capsules.
Influence of the Pneumogastrics upon the Liver. — There
is very little known with regard to the influence of the pneu-
mogastrics upon the secretion of bile. The only positive
statements to be found on this subject are those of Longet.3
This physiologist has repeatedly remarked, after section of
the pneumogastrics, that the bile diminishes in density and
contains less coloring matter than under normal conditions.
This he attributes to disturbances in the hepatic circulation,
by which a serous fluid is exuded and mixes with the bile.
1 BERNARD, Sf/steme nerveux, Paris, 1858, tome ii., p. 422.
8 CHAUVEAU, Du nerf pneumogaslrique, etc. — Journal de la physiologic, Paris,
1862, tome v., p. 205.
3 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 552.
ABDOMINAL NEEVES. 24:3
The disturbances in the circulation are somewhat similar to
those occasionally observed in the lungs. The vessels are
strongly injected, and sometimes contain clots of blood.
The hepatic tissue is more friable than usual, and presents a
greenish-black color.
The most important experiments upon the innervation
of the liver are those of Bernard, and relate to its glycogenic
function. TTe shall have little to say on this subject, how-
ever, in addition to what we have already stated in treating
of the liver as a sugar-producing organ.1 The view which
we have advanced with regard to the glycogenic function is
that the liver is constantly producing sugar during life,
which is completely washed out by the blood in its passage
through this organ, which itself contains little or no sugar,
under normal conditions. With this view, we are to look
for sugar in the blood, in certain situations, and not in the
liver itself; though after death, a change of the glycogenic
matter in the liver into sugar takes place with great rapidity,
and sugar may then be found in its tissue, formally, sugar
disappears in the lungs, and is not found in the blood of the
arterial system. The presence of sugar in the urine is ab-
normal.
Bernard found that if both pneumogastrics be divided in
the neck, and the animal be killed at a period varying from
a few hours to one or two days after, the liver contains no
sugar, under the conditions in which he generally found it ;
*. £., a certain time after death. From experiments of this
kind, he concludes that the glycogenic function is suspended
when the nerves are divided.2 The experiments, however,
made by irritating the pneumogastrics, are more satisfactory,
as in these he looked for sugar in the blood and in the urine,
and did not confine his examinations to the substance of
the liver.
After division of the pneumogastrics in the neck, if the
1 See vol. iii., Secretion, p. 324, et seq.
8 BERNARD, Lemons de physiologic experimentale, Paris, 1855, p. 324.
24:4 NERVOUS SYSTEM.
peripheral ends be galvanized, there is no effect upon the
liver ; but if galvanization be applied to the central ends,
the gljcogenic function becomes exaggerated, and sugar
makes its appearance in the blood and in the urine. Bernard
has made a number of experiments illustrating this point,
upon dogs and rabbits. The galvanic current employed was
generally feeble, and was continued for from five to ten
minutes, two or three times in an hour ; in some instances,
the irritation was kept up for thirty minutes.1 From these
experiments, it is assumed that the physiological production
of sugar by the liver is reflex, and is due to an impression
conveyed to the nerve-centres through the pneumogastrics.
A very interesting and adroit experiment by the same ob-
server shows that section of the pneumogastrics between the
lungs and the liver does not affect the production of sugar.
This delicate operation is performed by making a valvular
opening in the chest, preventing the ingress of air by sud-
denly forcing the finger into the wound, and then introdu-
cing a long, delicate hook with a cutting edge, and dividing
the nerves, which may be reached by the finger in small
dogs, and feel like tense cords by the side of the oesophagus.
We have already noted, in another volume,2 the fact ob-
served by Bernard and by Pavy, that the inhalation of irri-
tating vapors and of anaesthetics produces a hypersecretion
of sugar.
The remarkable effects of irritating the floor of the fourth
ventricle, by which we can produce temporary diabetes, have
been considered fully in connection with the glycogenic
function of the liver. This effect is not due to a direct trans-
mission of the irritation to the liver through the pneumo-
gastrics, for the phenomena of hypersecretion are observed
in animals upon which this operation has been performed
after section of both pneumogastrics in the neck. It is prob-
1 BERNARD, Lemons de physiologic experimentale, Paris, 1855, p. 325 ; and,
Systeme nerveux, Paris, 1858, p. 437, et seq.
8 See vol. iii., Secretion, p. 327.
NERVES. 245
able, indeed, that the impression is conveyed to the liver
through the sympathetic system, for it has been shown by
Schiff and Longet, that animals do not become diabetic after
irritation of the floor of the fourth ventricle, when the
branches of the sympathetic going to the solar plexus have
been divided.1 The operation, however, of dividing the
sympathetic nerves in this situation is so serious, that it may
interfere with the experiment in some other way than by
the direct influence of the nerves upon the liver.
Influence of the Pneumogastrics upon the Stomach and
Intestines. — The number of observations that have been
made upon the influence of the pneumogastric nerves on
digestion in the stomach is immense, and many of the earlier
experiments were quite contradictory. We do not propose,
however, to treat of this subject from a purely historical
point of view, for the reason that, before 1842 and 1843,
when gastric fistulas were first established in living animals,
by Bassow and Blondlot, little was known of the normal
movements of the stomach and of the mechanism of the
secretion of the gastric juice ; and farther, before the obser-
vations of Bouchardat and Sandras, in 1847, the effects of
section of the nerves in the neck upon the action of the
oesophagus in deglutition were not understood. If we study
the literature of the subject anterior to 1842, we find a great
deal of confusion, due to the facts just stated. Longet, in his
work on the nervous system, published in 1S42, gives an
excellent account of the various experiments up to that date.
He cites a great number of authors, Bichat, Tiedemann and
Gmelin, Bischoff, Schultz, Breschct and Milne Edwards,
Magendie, Miiller, Mayo, and many others, to whom we will
not refer in detail.2 Leaving out of the question, then, most
of the earlier experiments, we shall treat of the influence of
1 LOXGET, Traite de physiologie, Paris, 1869, tome Hi., p. 553.
* LOXGET, Anatomie et physiologie du systeme nerveux, Paris, 1842, tome iL,
p. 320, et seq.
246 NERVOUS SYSTEM.
the pneumogastrics upon the stomach and intestines, under
the following heads :
1. The effects of galvanization of the nerves.
2. The effects of section of the nerves upon the move-
ments of the stomach in digestion.
3. The effects of section of the nerves upon the secre-
tion of the gastric juice and the chemical processes of di-
gestion.
4. The influence of the nerves upon the small intestine.
Effects of Galvanization. — Bichat, in the first edition of
his great work on general anatomy, published in 1801, states
distinctly that irritation of the pneumogastrics produces con-
traction of the muscular coat of the stomach : "I remark
nevertheless that irritation of one of the vagus nerves, or of
both, immediately causes the stomach to contract, as occurs
in a voluntary muscle the nerve of which is irritated. It is
necessary, in performing this experiment, to open the abdo-
men of the living animal, and then to irritate the eighth
pair in the cervical region, in order to have under the eyes
the organ that is made to contract." 1 This fact was con-
firmed by Tiedemann and Gmelin,2 and many others, but
was denied by M tiller.3 In more recent experiments, the
effects of galvanization of the pneumogastrics upon the
movements of the stomach are unquestionable. Longet
shows that the stomach contracts as a consequence of irrita-
tion of the nerves, not instantly, but after the lapse of five
or six seconds. He explains some of the contradictory re-
sults obtained by other observers by the fact that these con-
tractions are very marked during stomach-digestion, while
they are wanting " when the stomach is entirely empty,
1 BICHAT, Anatomic generale, appligitee d la physiologic et d la pathologic,
Paris, 1801, seconde partie, tome iii., p. 360.
2 TIEDEMANN ET GMELIN, Recherches experimentalcs, physiologiques et chimiques,
Mir la digestion, Paris, 1827, premiere partie, p. 374.
8 MULLER, Elements of Physiology, London, 1840, vol. i., p. 530.
ABDOMINAL NEEVE3. 24:7
retracted on itself and in a measure in repose." According
to the same author, irritation of the splanchnic nerves, while
it produces movements of the intestines, does not affect the
stomach. Judging from the tardy contraction of the stom-
ach and the analogy between the action of the pneumo-
gastrics upon this organ and the action of the sympathetic
nerves upon the non-striated muscular tissue, Longet assumes
that the motor action of the pneumogastrics is due, hot to the
proper filaments of these nerves, but to filaments derived from
the sympathetic system. " This interpretation removes the
singular physiological anomaly that an organ, the action
of which is entirely removed from the control of the will,
should depend upon a voluntary, or cerebro-spinal nerve." l
This explanation of the contradictory results of experiments
and of the mechanism of the action of the pneumogastrics
upon the stomach seems entirely satisfactory, and may be
accepted without reserve.
Effects of Section of the Pneumogastrics upon the Move-
ments of the Stomach. — If the pneumogastrics be divided in
the neck in a dog in full digestion, in which a gastric fistula
has been established so that the interior of the organ can be
explored, the following phenomena are observed :
In the first place, before division of the nerves, the mu-
cous membrane of the stomach is turgid, its reaction is in-
tensely acid, and, if the finger be introduced through the
fistula, it will be firmly grasped by the contractions of the
muscular walls. When the pneumogastrics are divided, un-
der these conditions, the contractions of the muscular walls
instantly cease, the mucous membrane becomes pale, the
secretion of gastric juice is apparently arrested, and the sen-
sibility of the organ is abolished.3 Paralysis of the stomach,
etc., had been noted,3 long before the observations of Ber-
1 LOXGET, Traiti de physiologic, Paris, 1869, tome iii., p. 546.
2 BERNARD, Systems nerveux, Paris, 1858, tome ii., p. 422..
3 TIEDEMANN- ET GMELix, JKeckerches sur la digestion, Paris, 1827, premiere
partie, p. 373.
248 NERVOUS SYSTEM.
nard ; but his experiments on animals with a fistulous open-
ing into the stomach are the most striking.
Notwithstanding the apparent arrest of the movements
of the stomach in digestion by section of the pneumogastrics,
experiments carefully performed show that substances may
be very slowly passed to the pylorus, and that the move-
ments, though they are immensely diminished in activity,
are not entirely abolished. This fact has been established
beyond question by the experiments of Schiff, who attributes
the movements occurring after section of the nerves to local
irritation of the intramuscular terminal nervous filaments.1
Effects of Section of the Pneumogastrics upon Digestion,
etc. — Since the publication of the second volume of this work,
in which we considered briefly the action of the pneumogas-
trics in digestion, we have reviewed the literature of the sub-
ject, as well as the publications that have appeared since
that time, but we find little, if any thing, to add to the state-
ments already made.2 The facts with regard to the effects
of division of the nerves in the cervical region upon the se-
cretion of gastric juice are briefly as follows :
"When both nerves are divided, while an animal is in full
digestion, the mucous membrane becomes pale and flaccid,
and the secretion of gastric juice is apparently arrested at
once ; but if the animal survive the operation for a day or
two, a small quantity of juice may be secreted as the result
of local stimulation, and digestion of a very small quantity
of food, finely divided and introduced into the stomach
by a fistulous opening, may take place.3 A serious difficulty
in the digestion of large masses of food after division of the
nerves is due to the cessation of the movements of the
stomach. It is stated by Tiedemann and Gmelin, that di-
1 SCHIFF, Lemons sur la physiologic de la digestion, Florence et Turin, 1867,
tome ii., p. 389.
8 See vol. ii., Digestion, p. 283.
3 LONGET, Traite de physiologic, Paris, 18691, tome in., p. 649.
ABDOMINAL NERVES. 249
gestion may be to a certain extent reestablished, under these
conditions, by galvanizing the peripheral extremities of the
divided nerves.1
There is very little to be said with regard to the relations
of the pneumogastrics to the sensations of hunger and thirst.
It would be very natural to infer, from the distribution of
these nerves to the mucous membrane of the stomach, that
they should be involved in these sensations ; but in treating
of this subject elaborately, in connection with alimentation,
we have shown that hunger and thirst really have their ori-
gin in the general system, though the sensations are referred
subjectively to the stomach and fauces, and that, in all prob-
ability, the sensations persist after division of both pneumo-
gastrics.2
"With regard to the influence of the pneumogastrics upon
absorption from the stomach, we have also mentioned the
fact, demonstrated by Longet, that the passage of poisons
from the stomach into the blood-vessels may be retarded by
section of the nerves, but is not prevented.3
Physiologists have given but little attention to the influ-
ence of the pneumogastrics upon the intestinal canal, for the
reason that the distribution of the abdominal branches to
the small intestine, notwithstanding the researches of Koll-
mann, in 1860, does not appear to be generally recognized.
The right, or posterior abdominal branch was formerly sup-
posed to be lost in the sernilunar ganglion and the solar
plexus, after sending a few filaments to the stomach ; but since
it has been shown that this nerve is supplied to the whole of
the small intestine,4 its physiology, in connection with intes-
tinal secretion, has assumed considerable importance.
In an admirable series of experiments, by Prof. 'Horatio
C. Wood, Jr., of Philadelphia, the importance of the abdomi-
1 TIEDEMAXN ET GMELiy, RecJierches sur la digestion, Paris, 1827, premiere
partie, p. 373.
8 See vol. ii., Alimentation, p. 14.
4 See p. 211.
250 NEKVOTJS SYSTEM.
nal brandies of the right nerve is fully illustrated.1 These
experiments show, in the most conclusive and satisfactory
manner, that the pneumogastrics influence intestinal as well
as gastric secretion. One of the most interesting and curi-
ous points in connection with their function is, that after
section of the nerves in the cervical region, the most power-
ful cathartics, croton-oil, calomel, podophyllin, jalap, arsenic,
etc., fail to produce purgation, even in doses sufficient to
cause death. The articles used were either given by the
mouth, just before dividing the nerves, or were injected un-
der the skin.
Though the observations of Dr. "Wood are not entirely
new, they are by far the most extended and satisfactory, and
were made with a knowledge of the fact of the distribution of
the nerves to the small intestine. Dr. Wood quotes freely from
the experiments made by Sir Benjamin Brodie 2 and by Dr.
John Reid.3 Brodie failed to produce purging in dogs when
both pneumogastrics had been divided in the neck after the
administration of arsenic by the mouth and injecting it un-
der the skin. Dr. Reid made five experiments, and in all
but one, it is stated that diarrhoea existed after division of
the nerves. In twenty experiments by Dr. "Wood, there
was no purgation after division of the nerves, in one there
was free purgation, and in one there was " some slight muco-
fecal discharge." From these, Dr. Wood concludes, that
while section of the cervical pneumogastrics, in the great
majority- of instances, arrests gastro-intestinal secretion and
prevents the action of purgatives upon the intestinal canal,
1 WOOD, On the Influence of Section of the Cervical Pneumogastrics upon the
Action of JZmetics and Cathartics. — American Journal of the Medical Sciences,
Philadelphia, 1870, New Series, vol. lx., p. 75, et seg.
2 BRODIE, Experiments and Observations on the Influence of the Nerves of the
Eiglitli Pair on the Secretions of the Stomach. — Philosophical Transactions, Lon-
don, 1814, vol. xiv., p. 104.
3 REID, Experimental Investigation into the Functions of the Eighth Pair of
Nerves. — Physiological, Anatomical, and Pathological Researches, London, 1848,
p. 245, et seq.
SUMMARY OF THE PNEUMOGASTRICS. 251
a few exceptional cases occur in which these effects are not
observed.
The facts just mentioned are exceedingly interesting in
connection with the experiments of Traube upon the action
of digitalis after section of the pneumogastrics. It will be
remembered that, in these experiments, digitalis failed to
diminish the number of beats of the heart when the nerves
had been divided in the neck, showing that the separation
of the heart from its connections with the cerebro-spinal
system removed the organ from the peculiar and character-
istic effects of the poison.1
It would be interesting to determine whether the pneu-
mogastrics influence the intestinal secretions through their
own fibres or through filaments received from the sympa-
thetic system; but there are no experimental facts suffi-
ciently definite to admit of a positive answer to this question.
If the action take place through the sympathetic system, as
in the case of the stomach, the filaments of communication
join the pneumogastrics high up in the neck, and become
incorporated with the true fibres of the nerve in its trunk.
Summary of the Distribution, Properties, and Functions
of the Pneumogastrics. — The pneumogastrics have their ap-
parent origin from the lateral portion of the medulla oblon-
gata, just behind the olivary bodies, between the roots of
the glosso-pharyngeals and the spinal accessories. Their
deep origin is mainly from the gray substance in the floor
of the fourth ventricle. In their course, they each present
two ganglia, the ganglion of the root and the ganglion of the
trunk. They pass out of the cranial cavity on either side, by
the posterior foramen lacerum, with the glosso-pharyngeals,
the spinal accessories, and the internal jugular veins.
The nerves receive anastomosing branches from the spinal
accessories, facials, sublinguals, the anterior roots of the up-
per two cervicals, and the sympathetic. The nerves fre-
1 See p. 224.
252 NERVOUS SYSTEM.
quently send branches to the glosso-pharyngeals ; and fila-
ments joining others from the glosso-pharyngeals, the spinal
accessories, and the sympathetic, go to form the pharyngeal
plexus.
From above downward, the branches of the pneumogas-
trics are the following :
1. The auricular, distributed to the integument of the
upper portion of the external auditory meatus and to the
membrana tympani.
2. The pharyngeal, containing motor filaments derived
from the spinal accessory, distributed to the muscles and
mucous membrane of the pharynx.
3. The superior laryngeals, distributed to the mucous
membrane of the epiglottis, base of the tongue, aryteno-
epiglottidean folds, ventricles of the larynx and lining mem-
brane as far as the true vocal cords, and to the crico-thyroid
muscle. From these nerves and the main trunk of the
pneumogastrics, arise the so-called depressor-nerves of the
circulation.
4. The inferior laryngeals, turning around the great ves-
sels at the top of the thorax, pass up the neck, sending
filaments to the upper part of the oesophagus, trachea, and
the inferior constrictors of the pharynx, their terminal
branches supplying all of the muscles of the larynx except
the crico-thyroids.
5. The cervical and thoracic cardiac branches, going to
the cardiac plexus, to be distributed to the heart.
6. The anterior and posterior pulmonary branches, dis-
tributed to the pulmonary tissue, following out the bronchial
tree to its minutest ramifications, and sending a few fila-
ments to the trachea and to the pericardium.
7. The cesophageal branches, distributed to the lower
third of the oesophagus.
8. The abdominal branches, the left distributed to the
stomach and the liver ; and the right, sending a few fila-
ments to the stomach, and distributed finally to the liver,
SUMMARY OF THE PNEUMOGASTRICS. 253
spleen, kidneys, suprarenal capsules, and the whole of the
small intestine.
The true filaments of origin of the pneumogastrics are
exclusively sensory, and the nerves contain no motor fila-
ments, except, those derived from their anastomoses.
The sensory filaments of the auricular branches give sen-
sibility to the upper part of the external auditory meatus
and the membrana tympani. «
The motor filaments of the pharyngeal branches animate
the muscles of the pharynx. The sensory filaments are not
important in the reflex phenomena of deglutition, but prob-
ably contribute slightly to the general sensibility of the
pharynx.
The superior laryngeal nerves give sensibility to the up-
per portion of the larynx. They are exquisitely sensitive,
and, by their reflex action, aid in closing the larynx to the
entrance of foreign substances, and in the production of the
movements of deglutition. Stimulation of these nerves pro-
duces movements of deglutition and arrests the action of the
diaphragm. They animate, also, the movements of the crico-
thyroid muscles.
The inferior laryngeals contain chiefly motor filaments.
They embrace the filaments from the spinal accessories, which
preside over phonation. They also contain motor filaments
from other sources, which preside over the respiratory move-
ments of the glottis. Their division abolishes vocal sounds,
and, in young animals, causes death by suffocation, the glot-
tis being closed in inspiration. Galvanization of their cen-
tral ends, after division, generally produces movements of
deglutition and arrest of the action of the diaphragm.
The action of the cardiac branches has been studied by
experiments upon the pneumogastrics in the cervical region.
Division of the pneumogastrics in the neck increases the
number of pulsations of the heart. Galvanization of the
peripheral ends, after division, arrests the heart's action in
diastole, and galvanization of the central ends has no effect
254: NERVOUS SYSTEM.
on tlie circulation. The direct inhibitory action of the pneu-
mogastrics operates through filaments derived from the spinal
accessories. Galvanization of the " depressor-nerves " retards,
or may arrest the pulsations of the heart, by reflex action.
This occurs only when the central ends of the divided nerves
are stimulated. Galvanization of the central ends of these
nerves also diminishes the pressure of blood in the large ves-
sels. This is due to reflex action through the splanchnic
nerves, by which the vessels of the intestines are dilated.
No such effect is produced when the splanchnic nerves have
been divided. There is no entirely satisfactory explanation
of the influence of the pneumogastrics on the heart.
The action of the pulmonary branches has been studied
chiefly by observations on the pneumogastrics in the cervical
region. Division of the pneumogastrics in this situation, in
young animals, produces almost instant death by closure of
the glottis in inspiration. In animals full-grown, death oc-
curs in from two to five days, and the respiratory acts are
very much diminished in frequency. "When death occurs in
this way, the lungs are found partially or completely " car
nified." This is due to mechanical causes. The small pul-
monary vessels are ruptured by the excessively deep inspira-
tions, and blood is gradually effused and coagulates. The
pneumogastrics have but little to do in conveying to the
nerve-centres the sense of want of air which gives rise to
the respiratory movements. Galvanization of the central
ends of the pneumogastrics divided in the cervical region
has the following effects : A very feeble excitation accele-
rates, and a more powerful excitation retards respiration.
A sufficiently powerful excitation arrests respiration. Gal-
vanization of the peripheral ends has no effect on respira
tion.
The cesophageal branches supply only the lower third of
the oesophagus. The upper portion receives branches from
the inferior laryngeals, and the middle portion is supplied
by branches from the posterior pulmonary nerves. The sen-
SUMMARY. OF THE PlfEUMOGASTEICS. 255
sibility of tlie mucous membrane of the oesophagus, as well
as the movements of its muscular coat, depends upon these
branches. Division of the nerves paralyzes the oesophagus,
and galvanization of the roots of the pneumogastrics causes
the tube to contract in its entire length. When the nerves
are divided, the oesophagus may become distended with food
forced in by the constrictors of the pharynx, but little or
none passes to the stomach. Uegurgitation of food some-
times occurs under these conditions, the muscular coat of
the oesophagus contracting under the direct stimulus of dis-
tention.
The function of the abdominal branches has been studied
chiefly by operating on the pneumogastrics in the cervical
region. Division of the nerves produces congestion of the
liver, and sometimes slight extravasation, and renders the
bile somewhat watery. It also arrests, in from one to two
days, the glycogenic function of the liver. Galvanization
of the peripheral ends of the divided nerves has no effect
on the liver. Galvanization of the central ends exaggerates
the glycogenic function and renders animals diabetic. The
inhalation of irritating vapors or of anaesthetics has the same
effect. This action is reflex, and the direct stimulus to the
liver does not pass through the pneumogastrics, for division
of the nerves between the lungs and the liver has no influ-
ence on the production of sugar. Irritation of the floor of
the fourth ventricle, opposite the origin of the pneumogas-
trics, exaggerates the glycogenic function. The stimulus is
not propagated through the pneumogastrics, for the effect is
the same after both nerves have been divided. It probably
operates through the sympathetic,, for diabetes cannot be
produced after the branches going to the solar plexus have
been divided.
Section of the pneumogastrics in the neck paralyzes,
nearly but not entirely, the muscular coats of the stomach.
AYhen the section is made in an animal in full digestion, the
mucous membrane, from being tense and full of blood, be
117
256 NERVOUS SYSTEM.
comes pale and flaccid, and stomach-digestion is arrested.
Afterward, very feeble movements of the stomach may oc-
cur as the result of local irritation, and small quantities of
food, very finely divided, may be digested. Galvanization
of the nerves in the neck produces contractions of the mus-
cular coats of the stomach. This action probably takes place
through sympathetic filaments going to the pneumogastrics
high up in the cervical region. Section of the nerves slight-
ly retards absorption from the stomach.
After division of both pneumogastrics in the neck, purga-
tive poisons, given even in fatal doses, generally fail to pro-
duce watery discharges from the intestine.1
1 Compression of the pneumogastrics has lately been recommended by Wal-
ler to produce anaesthesia in surgical operations, etc. The effects of pressure
of these nerves in the human subject are described by Aristotle, quoted by
Waller. In some cases, the patient falls instantly, as if struck by lightning,
while in others the effects are not so marked. Waller has employed this method
for the production of anaesthesia under varied conditions, and has never ob-
served any serious after-effects. He relates a case of successful reduction of a
very difficult dislocation of the shoulder, which had resisted previous efforts,
after two or three minutes of simultaneous compression and traction. He also
relates a case of painless extraction of a tooth by the same means. The im-
possibility of compressing the pneumogastrics, in the human subject, without
disturbing the circulation in the brain by pressure on the carotids, in view of
the fact that cerebral anaemia produces anaesthesia, renders it impossible to ac-
cept, without reserve, the conclusions of Waller. (WALLER, On the Compression
of the Vagus Nerve, considered as a Means of producing Asthenia or Ancesthesia
in Surgical Operations, — Practitioner, London, December, 1870, No. xxx., p.
822.)
CHAPTER IX.
PHYSIOLOGICAL ANATOMY AND GENERAL PROPERTIES OF THE
SPINAL CORD.
General arrangement of the cerebro-spinal axis — Membranes of the encephalon
and spinal cord — Cephalo-raehidian fluid — Physiological anatomy of the
spinal cord — Direction of the fibres after they have penetrated the cord by
the roots of the spinal nerves — General properties of the spinal cord —
Effects of stimulation applied directly to different portions of the cord.
UNDER the head of special senses, we shall consider, in
another volume, the properties and functions of the first and
second nerves, the portio mollis of the seventh, or auditory,
and the gustatory nerves, comprising a part of the glosso-
pharyngeal and a small filament from the facial (the chorda
tympani) going to the lingual branch of the fifth. This will
include a full account of the organs of smell, sight, hearing,
and taste, with a description of the general sensory nerves,
as far as they are concerned in the sense of touch. "We will
here begin our history of the cerebro-spinal axis, which will
include the physiological anatomy, properties, and functions
of the encephalon and spinal cord.
General Arrangement of the Cerebro-spinal Axis. — The
nervous matter contained in the cavity of the cranium and
in the spinal canal, exclusive of the roots of the cranial and
spinal nerves, is known as the cerebro-spinal axis. This
portion of the nervous system is composed of white and
gray nervous matter. The fibres of the white matter act as
conductors. The gray matter constitutes a chain of ganglia,
258 - NERVOUS SYSTEM.
whicli act as nerve-centres, receiving impressions and gen-
erating the so-called nerve-force. The gray matter of the
spinal cord also serves, to a greater or less extent, as a con-
ductor.
The cerebro-spinal axis is enveloped in membranes, for
its protection and for the support of its nutrient vessels. It
is surrounded, to a certain extent, with liquid, and presents
cavities, as the ventricles of the brain and the central canal
of the cord, which contain liquid. The gray matter is dis-
tinct from the white, even to the naked eye. In the spinal
cord, the white substance is external and the gray is internal.
The surface of the brain presents an external layer of gray
matter, the white substance being internal. In the white
substance of the brain, also, we find collections of gray
matter. As we should expect from the similarity in func-
tion between the white matter and the nerves, this por-
tion of the cerebro-spinal axis is composed largely of fibres.
The gray substance is composed chiefly of cells.
The encephalon is contained in the cranial cavity. In
the human subject and in many of the higher animals, its
surface is marked by numerous convolutions, by which the
extent of its gray substance is very much increased. The
cerebrum, the cerebellum, and all of the encephalic ganglia
are connected with the white substance, and are contin-
uous with the spinal cord. With the encephalon and the
cord, all of the cerebro-spinal nerves are connected. The
cerebro-spinal axis acts as a conductor, and its different col-
lections of gray matter, or ganglia receive impressions con-
veyed by the sensory conducting fibres, and generate nerve-
force, which is transmitted to the proper organs by the motor
fibres.
Membranes of the Encephalon and Spinal Cord. — The
membranes of the brain and spinal cord are, the dura mater,
the arachnoid, and the pia mater.
The dura mater of the encephalon is a dense, fibrous
CEKKBRO-SPESTAL AXIS. 259
membrane, in two layers, composed chiefly of inelastic tis-
sue, which, lines the cranial cavity and is adherent to the
bones. In certain situations, its two layers become sepa-
rated and form what are known as the venous sinuses. The
dura mater also sends off folds or processes of its internal
layer ; one of these passes into the longitudinal fissure, and
is called the falx cerebri ; another lies between the cerebrum
and the cerebellum, and is called the tentorium; another
is situated between the lateral halves of the cerebellum, and
is called the falx cerebelli. The dura mater is closely at-
tached to the bone at the border of the foramen magnum,
From this point, it passes into the spinal canal and forms a
loose covering for the cord. In the spinal canal, this mem-
brane is not adherent to the bones, which have, like most
other bones in the body, a special periosteum. At the fora-
mina of exit of the cranial and the spinal nerves, the dura
mater sends out processes which envelop the nerves, with
the fibrous sheaths of which they soon become continuous.
The arachnoid is an excessively delicate serous membrane,
in two layers, the surfaces of which are nearly in contact. The
external layer lines the internal surface of the dura mater.1
Like the other serous membranes, the arachnoid is covered
with a layer of tessellated epithelium. There is a small
amount of liquid between the two layers of the arachnoid ;
but by far the greatest quantity of liquid surrounding the cere-
bro-spinal axis lies beneath both layers, in what is called the
subarachnoid space. This is called the cerebro-spinal, or
cephalo-rachidian fluid. The fact that it exists in greatest
quantity beneath both layers of the arachnoid was first
pointed out by Magendie.3 The arachnoid does not follow
the convolutions and fissures of encephalon or the sulci of
1 According to Kolliker, the arachnoid consists of a single layer, the layer
attached to the dura mater being not properly a membrane, but simply an
epithelial covering (Handbuch der Gewebelehre, Leipzig, 1867, S. 308).
2 HAGEXDIE, JRecherches physiologiques et cliniques sur le liquide cephalo-
rachidien, Paris, 1842.
260 NERVOUS SYSTEM.
the cord, but simply covers their surfaces. Magendie point-
ed out a longitudinal, incomplete, cribriform, fibrous septum
in the cord, passing from the inner layer of the arachnoid to
the pia mater. A similar arrangement is found in certain
situations at the base of the skull.1
The pia mater of the encephalon is a delicate fibrous
structure, exceedingly vascular, seeming to present, indeed,
only a skeleton net-work of fibres for the support of the ves-
sels going to the nervous substance. This membrane cov-
ers the surface of the encephalon immediately, follows the
sulci and fissures, and is prolonged into the ventricles, where
it forms the choroid plexus and the velum interpositum. From
its internal surface, small vessels are given off which pass
into the nervous substance.
The pia mater of the encephalon is continuous with the
corresponding membrane of the cord ; but in the spinal
canal, it is thicker, stronger, more closely adherent to the
subjacent parts, and its blood-vessels are by no means so
numerous. In this situation, many of the fibres are arranged
in longitudinal bands. This membrane lines the anterior
sulcus and a portion of the posterior sulcus. It is sometimes
spoken of as the neurilemma of the cord.
At the foramina of exit of the cranial and the spinal
nerves, the fibrous structure of the pia mater becomes con
tinuous with the nerve-sheaths.
Between the anterior and posterior roots of the spinal
nerves on either side of the cord, is a narrow ligamentous
band, the ligamentum denticulatum, which assists in holding
the cord in place. This extends from the foramen magnum
to the terminal filament of the cord, and is attached, inter-
nally, to the pia mater, and externally, to the dura mater.
It is not necessary to enter into a detailed description of
the arrangement of the blood-vessels, nerves, and lymphatics
of the membranes of the brain and spinal cord, or of the vas-
cular arrangement in the substance of the cerebro-spinal axis,
1 MAGENDIE, op. cit., p. 14.
CEPHALOKACHIDIAN FLUID. 261
as these points are chiefly of anatomical interest. The circu-
lation in these parts presents certain peculiarities. In the
first place, the encephalon being contained in an air-tight
case of invariable capacity, it has been a question whether
or not the vessels be capable of contraction and dilatation,
or whether the quantity of blood in the brain be subject to
modification in health or disease. This question may cer-
tainly be answered in the affirmative. In infancy and in the
adult, when an opening has been made in the skull, the volume
of the encephalon is evidently increased during expiration and
is diminished in inspiration. Under normal conditions, in the
adult, it is probable that the amount of blood is increased in
expiration and diminished in inspiration ; but it is not prob-
able that the cerebro-spinal axis undergoes any considera-
ble movements. The important peculiarities in the cerebral
circulation have already been folly considered in another
volume.1
An important fact was pointed out by Hobin, and after-
ward by His, with regard to the arrangement of the lym-
phatic vessels of the brain. It was shown by these observers,
that the encephalic capillaries are surrounded or nearly sur-
rounded by canals (perivascular canal-system) which exceed
the blood-vessels in diameter by from y^Vo to TJ-0- of an
inch, and are connected with lymphatic trunks or reservoirs
situated under the pia mater.8 The system of canals may,
by variations in its contents, serve to equalize the amount
of liquid in the brain as its blood-vessels are distended or
contracted.
Cephalo-rachidian Fluid. — The older writers referred
to in works upon physiology, as giving the most accurate
description of the cephalo-rachidian fluid, are Haller3 and
Cotugno;4 but it remained for Magendie, in 1825, to de-
1 See vol. i., Circulation, p. 332. * See vol. ii., Absorption, p. 433.
3 HALLER, Elemento Physiologies, Lausannae, 1762, tomus iv., p. 87.
4 Extraii de la dissertation de COTUGXO, de Ischiade Nervosa, content dans le
262 NERVOUS SYSTEM.
scribe its exact situation, with the communications between
the different cavities of the brain and the subaraclmoid
space.1 By a series of ingeniously-contrived experiments
upon the cadaver and in living animals, Magendie showed
that the greater part of the fluid in the cranium and the
spinal canal is contained in what is known as the sub-
arachnoid space; that is, between the inner layer of the
arachnoid and the pia mater, and not between the two lay-
ers of the arachnoid. The ventricles of the encephalon are
in communication with the central canal of the cord, and, as
was shown by Magendie, they are also in communication
with the general subaraclmoid space, by a narrow, triangu-
lar orifice, situated at the inferior angle of the fourth ventri-
cle. By this arrangement, the liquid in the ventricles of the
encephalon and the central canal of the cord communicates
with the liquid surrounding the cerebro-spinal axis, and the
pressure upon these delicate parts is equalized.
As far as we know, the function of the cephalo-rachidian
fluid is simply mechanical, and its properties and composi-
tion have no very definite physiological significance. Its
quantity was estimated by Magendie at about two fluid-
ounces ; a but this was the smallest amount obtained by
placing the subject upright, making an opening in the lum-
bar region and a counter-opening in the head to admit the
pressure of the atmosphere. The exact quantity in the liv-
ing subject could hardly be estimated in this way ; and it is
difficult, indeed, to see how any thing more than a roughly
approximative idea could be obtained. The quantity ob-
tained by Magendie probably does not represent the entire
amount of liquid contained in the ventricles and in the sub-
TJicmurus Dissertationum de SANDIFERT, tome ii., p. 411, Koterdara, 1769. —
Journal de physiologic, Paris, 1827, tome vii., p. 83.
1 MAGENDIE, Memoire sur un liquids qui se trouve dans le crane et le canal
vertebral de Vhomme et des animaux mammiferes. — Journal de physiolcgie, Paris,
1825, tome v., p. 27; Ibid., 1827, tome vii., pp. 1, 66; and, Recherches phy'siolo-
giques el d'miques sur le liquide cephalo-rachidien, Paris, 1842.
2 MAGENDIE, Liquide cephalo-rachidien, Paris, 1842, p. 36.
CEPHALCKRACHIDIAN FLUID. 263
araclmoid space, but it is the most definite estimate that has
been given.
The discharge of a certain quantity of the cephalo-rachid-
ian fluid does not produce any marked derangement in the
action of the nervous system. In the first experiments of
Magendie, in which the muscles of the neck and the occipito-
atloid ligament were divided, the animals were affected with
irregular movements, general paralysis, etc. ; * but it is stated
by Longet 2 and by Bernard, that these phenomena are due
to the division of the parts involved in the operation, and
not to the removal of the liquid. When the liquid is al-
lowed to flow spontaneously through a small trocar intro-
duced without division of the muscles of the neck, there fol-
lows no serious nervous disturbance ; but when the liquid is
drawn out forcibly with a syringe, the animal first becomes
enfeebled, and afterward seems affected with general paraly-
sis. These phenomena are attributed by Bernard, not so
much to removal of the fluid, as to congestion of blood-ves-
sels and even effusion of blood, which follow sudden dimi-
nution in the pressure.3
Sudden increase in the quantity of liquid surrounding
the cerebro-spinal axis produces coma, probably from com-
pression of the centres. This was shown by Magendie, by
injecting water in animals, and also by compressing the tu-
mor, in cases of spina bifida in the human subject, by which
the fluid was pressed back into the spinal canal. In the
cases of spina bifida, the subject, during the compression,
fell into coma, which was instantly relieved by removing
the pressure.4
It was ascertained by Magendie, and this has been con-
firmed by all later observers, that the cephalo-rachidian fluid
1 MAGENDIE, Liquide cephalo-rachidien, Paris, 1842, p. 58.
2 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 305.
3 BERNARD, Sy&teme nerveux, Paris, 1858, tome i., p. 496, et seq.
Bernard states that Magendie recognized the error in his first interpretation of
the phenomena following removal of the cephalo-mchidian fluid (Ibid., p. 496).
4 MAGENDIE, op. cit., p. 60.
264 NEKVOTTS SYSTEM.
is speedily reproduced after its evacuation. In all probabil-
ity, it is secreted by the pia mater.1
The general properties and composition of the fluid un-
der consideration are, in brief, the following : 2 It is perfectly
transparent and colorless, free from viscidity, of a distinctly
saline taste, alkaline reaction, and resists putrefaction for
a long time. It is not affected by heat or acids. As we
should expect from its low specific gravity and purely me-
chanical function, it contains a large proportion of water ;
981 to 985 parts per thousand. It contains a considerable
quantity of chloride of sodium, a trace of chloride of potas-
sium, sulphates, carbonates, and alkaline and earthy phos-
phates. In addition, it contains traces of urea, glucose, lac-
tate of soda, fatty matter, cholesterine, and albumen.
As a summary of the function of the cephalo-rachidian
fluid, it may be stated, in general terms, that it serves to
protect the cerebro-spinal axis, chiefly by equalization of the
pressure in the varying condition of the blood-vessels, accu-
rately filling the space between the centres arid the bony
cavities in which they are contained. That the blood-vessels
of the cerebro-spinal axis are subject to variations in tension,
is readily shown by introducing a canula into the subarach-
noid space, when the jet of fluid discharged will be increased
with every violent muscular effort.3 The pressure of the
fluid, in this instance, could only be affected through the
blood-vessels.
Physiological Anatomy of the Spinal Cord.
The spinal cord, with its membranes, the roots of the
spinal nerves, and the surrounding liquid, occupies the spinal
canal and is continuous with the encephalon. Its length is
from fifteen to eighteen inches, and its weight is about an
ounce and a half. Its form is cylindrical, slightly flat-
1 Op. cit, pp. 38, 39.
2 ROBIN, Le$ons sur las humeurs, Paris, 1867, p. 259.
3 MAQENDIE, Journal de physiologic, Paris, 1827, tome vii., p. 9.
ANATOMY OF THE SPINAL COED. 265
tened in certain portions. It extends from the foramen
magnum to the first lumbar vertebra. It presents, at the
origin of the brachial nerves, an elongated enlargement, and
a corresponding enlargement at the origin of the nerves
which supply the lower extremities. It terminates below in
a slender, gray filament, called the filum terminale. The
sacral and coccygeal nerves, after their origin from the lower
portion of the cord, pass downward to emerge by the sacral
foramina, and form what is known as the cauda equina.
The substance of the cord is formed of white and gray
matter, the white matter being external. The proportion
of white matter to the gray is greatest in the cervical region.
This fact is important in studying the course of the fibres
and in view of the functions of the cord as a conductor.
The inferior, pointed termination of the cord consists en-
tirely of gray matter.
The cord is marked by .an anterior and a posterior me-
dian fissure, and by imperfect and somewhat indistinct an-
terior and posterior lateral grooves, from which arise the
anterior and the posterior roots of the spinal nerves. The
posterior lateral groove is tolerably well marked, but there
is no distinct line at the origin of the anterior roots. The
anterior median fissure, or sulcus, is perfectly distinct. It
penetrates the anterior portion of the cord in the median
line for about one-third of its thickness, and receives a high-
ly-vascular fold of the pia mater. It extends to the anterior
white commissure. The posterior fissure is not so distinct
as the anterior, and is not lined throughout by a fold of the
pia mater, but is filled with connective tissue and blood-ves-
sels, which form a septum posteriorly, between the lateral
halves of the cord. The posterior median fissure, so called,
extends nearly to the centre of the cord, to the posterior
gray commissure.
Physiologically and anatomically, the cord is divided
into two lateral halves ; but the division of each half into
columns is not so distinct. Anatomists generally regard a
NERVOUS SYSTEM.
half of the cord as consisting of three columns : The ante-
rior column is bounded by the anterior fissure and the ori-
gin of the anterior roots of the spinal nerves ; the lateral
column is included between the anterior and the posterior
roots of the nei'A^es ; the posterior column is bounded by the
line of origin of the posterior roots and the posterior fis-
sure. Some anatomists include the lateral with the anterior
column, under the name of the antero-lateral column, taking
in about two-thirds of the cord. Next the posterior median
fissure, is a narrow band, marked by a faint line, which is
sometimes called the posterior median column.
The arrangement of the white and the gray matter in
the cord is seen in a transverse section. The gray substance
is in the form of a letter H, presenting two anterior and two
posterior cornua connected by whatsis called the gray com-
missure. The anterior cornua are the shorter and broader,
and do not reach to the surface of the cord. The posterior
cornua are larger and narrow, and extend nearly to the sur-
face, at the point of origin of the posterior roots of the spi-
nal nerves. In the centre of the gray commissure, is a very
narrow canal, lined by cells of ciliated epithelium, called the
central canal. This is in communication above with the
fourth ventricle, and extends below to the filum terminale.
That portion of the gray commissure in front of this canal
is sometimes called the anterior gray commissure, the poste-
rior portion being known as the posterior gray commissure.
The central canal is immediately surrounded by connective
tissue. In front of the gray commissure, is a mass of white
substance known as the anterior white commissure.
The proportion of the white to the gray substance is
variable in different portions of the cord. In the cervical
region, the white substance is most abundant, and, in fact,
it progressively increases in quantity from below upward
throughout the whole extent of the cord. In the dorsal
region, the gray matter is least abundant, and it exists in
greatest quantity in the lumbar enlargement.
ANATOMY OF THE SPINAL COED. 267
The white substance of the cord is composed of nerve-
fibres, connective-tissue elements, and blood-vessels, the lat-
ter arranged in a very wide and delicate plexus. The nerve-
fibres are variable in their size, and are composed of the
axis -cylinder surrounded by the medullary substance, with-
out, however, the investing membrane. AYe will speak far-
ther on of the direction of the fibres in the cord.
The anterior cornua of gray matter contain blood-vessels,
connective-tissue elements, very fine nerve-fibres, and large
multipolar nerve-cells, which are sometimes called motor
cells. The posterior cornua are composed of the same ele-
ments, the cells being much smaller, and the fibres exceed-
ingly small, presenting very fine plexuses. The cells in this
situation are sometimes called sensory cells. I^ear the pos-
terior portion of each posterior cornu, is an enlargement, of
a gelatiniform appearance, containing numerous small cells
and fibres, called the substantia gelatinosa.
The foregoing description of the different structures and
parts of the cord is necessary to a comprehension of the di-
rection of the fibres in the spinal axis and their connections
with the nerve-cells, which is the anatomical basis of our
knowledge of its physiology. The connections between the
cells and the fibres have already been described in the chap-
ter on the general structure of the nervous system.1 The
multipolar nerve-cells are supposed to present certain pro-
longations which do not branch and are directly connected
with the medullated nerve-fibres. These are called nerve-
prolongations. In addition, fine, branching poles are de-
scribed under the name of protoplasmic prolongations.
The direction of the fibres in the cord is one of the most
difiicult and complicated questions in physiological anatomy ;
and, especially as regards the posterior roots of the nerves,
is one which cannot as yet be elucidated by purely anatomi-
cal investigations, but requires the aid of experimental and
pathological observations.
1 See page &0.
NEKVOUS SYSTEM.
Direction of the Fibres after they have penetrated itie
Cord l)y ih^e Roots of the Spinal Nerves. — In order to under-
stand fully the importance of this question, it is necessary to
bear in mind the following physiological facts :
1. The cord serves as a conductor of impressions to the
brain, conveyed to it through the posterior roots, and of
stimulus generated by the brain and passing from the cord
by the anterior roots of the spinal nerves. This action is
crossed, the decussation taking place mainly at the medulla
oblongata, for the anterior portions, and throughout the
whole extent of the cord, for the posterior portions.
2. Independently of its action as a conductor, the cord,
disconnected from the rest of the cerebro-spinal axis, acts as
a nerve-centre, by virtue of its gray matter and the fibres
connected with the cellular elements of this substance.
Bearing in mind these points, which are matters of posi-
tive demonstration, we are prepared to study the anatomical
relations of the fibres and cells. In this, we cannot follow
minutely and critically discuss the elaborate investigations
of Stilling, Clarke, Kolliker, Yan der Kolk, Gerlach, Dean,
and others, without treating extensively of points which pos-
sess a purely anatomical and a more or less controversial in-
terest ; and we will content ourselves with the following very
recent description, quoted in full from Gerlach, which em-
bodies about all of our positive knowledge of the subject,
presented in the clearest manner possible. This extract, the
translation of which is almost literal, should be carefully
studied by those who desire to learn what is known at the
present day with regard to the physiological anatomy of the
cord. As a preparation for this study, it would be well to
closely examine Fig. 10, which gives a general view of the
different parts of the cord, shown in a transverse section :
" With the present methods and means of investigation
at our command, we can scarcely give an exact, detailed de-
scription of the course of the fibres in the spinal cord, the
ground-work of the physiology of this organ. Investigations
AXATOMY OF THE SPIXAL COKD.
269
up to this time afford at least the outlines of a sketch which,
as regards the course of the fasciculi of the anterior roots,
has a tolerably definite basis ; and, on the other hand, with
FIG. 10.
Transverse section of the spinal cord of a child six months old, at the middle of the lumbar en-
largement treated with potassio-chloride of gold and nitrate of uranium i>y means of these
.ts. the direction of the fibres in the gray substance is rendered unusually distinct.
Magnified 20 diameters. — a, anterior columns; 6. posterior columns: c. lateral columns;
d, anterior roots ; e, posterior roots ; f, anterior white commissure, in communication with
the fasciculi of the anterior cornua and the anterior columns ; g, central canal with its epithe-
lium; //, surrounding connective substance of the central canal; i. transverse fasciculi of the
gray commissure in front of the central canal; l\ transverse fasciculi of the gray commissure
behind the central canal ; £, transverse section of the two central veins ; m. anterior cornua ;
11. great lateral cellular layer of the anterior cornna ; o. lesser anterior cellular layer; p. small-
est, median cellular layer"; g. posterior cornua ; r, ascending fasciculi in the posterior cornua ;
*. substantia gelatinosa (GERLACIL in STEICKEB, Ilandbudi der Lehre von, den Geweben,
Leipzig, 1868, S. 666).
regard to the fasciculi going to the spinal cord through the
posterior roots, is quite incomplete and uncertain.
" The fasciculi of the anterior roots, after their entrance
into the cord, pass diagonally through the white substance,
270 NEKVOUS SYSTEM.
and, as such, are not at all concerned in its formation. On
the contrary, they pass immediately to the gray substance
of the anterior cornua, and, by their prolongations, are in
direct connection with the nerve-cells in this situation, which,
accordingly, are to be regarded as the elements of origin of
the anterior roots in the cord. The protoplasmic processes
of these nerve-cells form parts of the fine plexuses of nerve-
fibres in the gray substance, from which larger nerve-fibres
take their origin. These, extending in two directions, leave
the gray substance, to pass up in the white substance to the
brain. In consequence of the entrance of additional nerve-
fibres, the white substance is necessarily increased in quan-
tity in the cord from below upward. "With regard to the
course of the fasciculi which pass out of the gray substance
of the anterior cornua, these are to be divided into median
and lateral. The median fasciculi pass immediately into the
anterior white commissure, where they decussate writh corre-
sponding fasciculi from the opposite side, to pass upward
again in the anterior column of the other half of the cord.
The lateral fasciculi go to the lateral columns of the same side,
in which they pass to the brain, having first undergone de-
cussation in the anterior pyramids of the medulla oblongata.
" The posterior nerve-roots enter horizontally, running
in the white substance of the spinal cord, in a direction from
without inward toward the median line, and here divide into
two portions. The lateral portion, the smaller, retains the
horizontal direction, and passes through the substantia gelati-
nosa, dividing into fine and the finest bundles, in the man-
ner mentioned above, to take part in the formation of the
vertical bundle of fibres which lie immediately in front.
Here the fibres pass onward, a portion of them ascending
and a portion descending. The fibres of the lateral portion
of the posterior roots do not remain very long in the verti-
cal bundle, but curve forward in an horizontal plane, and in-
this way reach the portion of the posterior cornua containing
a fine plexus of nerve-fibres.
AX ATOMY OF THE SPIXAL CORD. 271
" The median (larger) portion of the posterior root-fibres
passes to that portion of the posterior, column which bounds
the substantia gelatinosa internally and posteriorly ; and
curving, takes here a vertical course to pass into the poste-
rior columns, extending chiefly upward, but perhaps down-
ward as well. The median posterior root-fibres then undergo
another deflection, by which they again take an horizontal
direction, and pass to the gray substance of the posterior
cornua, in part through the median portion and in part by
the inner border of the substantia gelatinosa. With regard
to the further course of the posterior root-fibres, it is impos-
sible to present positive explanations, for the reason that the
present methods of investigation do not afford any means of
distinguishing the posterior fibres from the nerve-tubes in
the vertical fasciculi of the posterior cornua, or those passing
from the gray substance into the posterior columns, to ascend
to the brain. The numerous divisions which the posterior
root-fibres penetrating the posterior cornua immediately
undergo indicate, however, that a portion of them is lost
directly in the fine nerve-plexus of the gray substance. But
at the same time there are numerous fibres which extend
forward, and others which take a more or less wavy course
toward the median line. The first, perhaps, can be regarded
as posterior root-fibres, which pass in a forward direction in
the nervous plexus ; the latter, on the other hand, belong to
the commissural fibres, which cross the median line in the
gray substance in front of and behind, the central canal. In
my opinion, the fibres which penetrate the posterior com-
missure are not to be regarded as belonging directly to the
posterior roots, but are to be considered as fibres which pass
backward to go either to the vertical fasciculi of the gray
substance, or to pass to the brain in the posterior columns.
If this idea be correct, and it is sustained by analogous con-
ditions in the anterior cornua, the following view may be
given of the course of the fibres of the posterior roots which
penetrate the gray substance : ' A portion of the posterior
118
272 NEKVOUS SYSTEM.
root-fibres, immediately after their entrance into that por-
tion of the gray substance which contains a nerve-plexus,
is lost in this plexus ; another portion extends farther for-
ward, and, in proportion as the fibres pass forward, they
likewise take part, by constant divisions, in the formation
of the nerve-plexus. This plexus, in which larger and small-
er nerve-cells are interspersed as it were as knotted points
(Knotenpunkte), are in direct connection with the plexus of
the anterior cornua. From these cells nerve-fibres arise,
which cross the median line in the gray commissure in front
of and behind the central canal, then curve backward, to
pass up to the brain, in part in the vertical fasciculi of the
posterior cornua, in part in the posterior columns, between
both of which numerous connections may exist which are
as yet inextricable.' This view involves a complete decus-
sation in the spinal cord, through the fibrous elements of
the posterior roots passing into this part. Whether this
be in reality a complete or a partial decussation in this
situation, a part of the fibres arising from the nerve-
plexus passing simply backward without crossing the me-
dian line, cannot be determined by definite anatomical in-
vestigations ; but pathological researches, as well as the
experimental results of that most competent observer,
Brown-Sequard, are decidedly in favor of a complete decus-
sation.
" Finally, it must be admitted that two points especially
are evident :
ul. In the direction of the nerve-fibres which enter
through the posterior roots, the gray substance has more
numerous connections than in those which pass to the spi-~
nal cord through the anterior roots.
" 2. The morphological distinction determinable between
the anterior and the posterior roots is, that the former take
their origin directly from the nerve-cells by means of the
nerve-prolongations, while in the latter, it is only indirect
through the nerve-plexus with the protoplasmic prolonga-
GENERAL PROPERTIES OF THE SPINAL CORD. 273
tions, and in this wise they are in communication with the
nerve-cells."
General Properties of ike Spinal Cord.
In treating of the functions of the spinal cord, we shall
consider, first, its general properties, as shown by direct
stimulation of its substance in different situations ; next, its
functions as a conductor ; and, finally, its action as a nerve-
centre.
The first indication that the different columns of the
cord are possessed of different properties is to be found in
the experiments of Magendie. This observer, however, was
somewhat indefinite in his conclusions, particularly with re-
gard to the anterior columns ; but he stated distinctly that
the posterior columns are sensitive : " If we lay bare the
cord in any portion of its extent, and if we touch, or prick
slightly posteriorly, the two fasciculi situated between the
posterior roots, the animal gives signs of exquisite sensibil-
ity ; if, on the other hand, we make the same trials upon
the anterior portion, the evidences of sensibility are scarcely
apparent." a Since this time, numerous observers have ex-
perimented upon the different columns, both at the surface
and in the deep portions of the cord, with varying results.
These observations we do not propose to discuss fully in
detail, but will refer simply to certain of them, made within
a few years, with the advantage of a knowledge of the
reflex phenomena following irritation of the cord, which
must always be taken into consideration in such experiments.
In 1861, Chauveau, as the result of numerous experi-
ments performed upon horses, cows, sheep, goats, rabbits,
pigs, dogs, and cats, stated that the antero-lateral columns
of the cord were inexcitable, both at the surface and in the
1 GERLACH, in STRICKER, Handbuch der Lehre von den Geweben, Leipzig, 1868,
S. 691, et seq.
• MAGEXDIE, Note sur le siege du mouvement et du sentimerd dans la moelle
epinere. — Journal de physiologic, Paris, 1823, tome iiL, p. 163.
274 NERVOUS SYSTEM.
deep portions. The facts upon which this assertion was
based were, that direct stimulation of these portions of the
cord in living animals, whether by mechanical means or by
feeble galvanic shocks, produced no contraction of muscles
and no pain. Upon irritating the posterior columns, either
by mechanical or galvanic stimulus, Chauveau noted pain
and reflex movements when the irritation was applied to the
surface, but the results were negative when the deep por-
tions of the columns were operated upon. The surface of
the posterior columns seemed to possess the same general
properties as the posterior roots of the nerves, especially
near the roots, where the sensibility was most marked,
gradually diminishing in intensity toward the median line ;
but the deep portions of the cord were everywhere found
completely insensible and inexcitable.1
The experiments and conclusions of Chauveau have a
most important bearing upon the physiology of the cord,
and are opposed to the views of the majority of physiologi-
cal writers, though they have been admitted by some experi-
menters. We shall discuss first the experiments upon the
antero-lateral columns, which are most remarkable in their
negative results. In this we shall use the term excitability
as signifying the property of the cord which enables it to
conduct a stimulus applied directly to it to certain muscles,
producing convulsive movements confined to these muscles,
and not of a reflex character. We shall apply the term
sensibility to the property by virtue of which an irritation
directly applied is conveyed to the brain and produces a
painful impression.
The experiments of Chauveau and some others upon the
antero-lateral columns are simply negative ; but their results
are directly opposed to those of numerous experimenters,
who have produced local and restricted convulsive move-
ments by direct irritation of both the superficial and the
1 CHAUVEAU, De TexcitaUlite de la moelle epinere. — Journal de la physiologic,
Paris, 1861, tome iv., p. 369.
GENERAL PROPERTIES OF THE SPINAL CORD. 275
deep portions of these columns. The experiments of Lon-
get, for example, made in 1840, have been repeatedly con-
tinued by more recent observations. Longet exposed the
lumbar portion of the cord in a large-sized dog and divided
it transversely. Galvanization of the antero-lateral columns
of the inferior portion always produced convulsive move-
ments, while the result of irritation of the posterior columns
was simply negative. On the other hand, galvanization of
the posterior columns of the superior segment of the cord
produced intense pain, and no effect followed irritation of
the antero-lateral columns.1 These results, being positive,
are to be accepted in opposition to the negative results
obtained by Chauveau, provided it can be shown that the
stimulus did not extend from the cord to the roots of the
nerves, a reservation which is important in all experiments
in which the nerves are irritated with galvanism. Upon
this point, we have some experiments, made in 1863, which
will be detailed after we have discussed the properties of the
posterior columns.
With regard to the posterior columns, the views of Chau-
veau are in advance of those of previous observers, only in
so far as he has shown that, although the surface of this
portion of the cord is endowed with sensibility, its deeper
portions are entirely insensible, except in the immediate
proximity of the posterior roots of the nerves.
In view of the importance of the question under consid-
eration, and of the contradictory results of experiments, we
repeated, in 1863, the experiments of Chauveau, under con-
ditions as nearly physiological as possible. We had often
had occasion to note the diminished sensibility of the roots
of the spinal nerves immediately following the very severe
operation of opening the spinal canal, and had also noted
that the sensibility increased, probably approaching the nor-
mal standard, after the animal had been allowed a few hours
1 LONGET, Anatomic ft physiologie du systeme nerveux, Paris, 1842, tome i.,
p. 272, et seq.
276 NERVOUS SYSTEM.
of repose. For this reason, we made our observation about
two hours after the first operation. To avoid the suspicion
of an extension of the galvanic current beyond the portion
of the cord which we desired to stimulate, the irritation was
first made by simply scratching the parts with the point of
a needle. The following experiment is the type of several,
in all of which the results were identical :
May 28, 1863, at 1 P. M., the laminae and the spinous
processes of the three lower lumbar vertebrae were removed
from a medium-sized dog. There was no very great haem-
orrhage. The spinal cord and the roots of three of the
nerves were exposed, and the wound was then closed. The
operation was performed with the animal under the influ-
ence of ether, and lasted about three-quarters of an hour.
About two hours after the first operation, the animal was
brought before the class at the Long Island College Hospi-
tal. The wound was opened, and the properties of the an-
terior and posterior roots were demonstrated. The follow-
ing observations were then made on the spinal cord :
The external surface of the posterior columns was irri
tated by scratching with the point of a needle. This pro-
duced pain, the more marked, the nearer the irritation was
brought to the origin of the posterior roots. The surface
was almost insensible at the median line. A feeble galvanic
stimulus was then applied by means of a plnce electrique,
with the same results. The deep portions of. the posterior
columns were then irritated without effect.
The cord was then divided transversely, and mechanical
and galvanic stimulus were applied to the cut surfaces.
The surface of the upper end of the cord was irritated
with the needle, and the needle was plunged deeply into its
substance, without effect. The same negative results fol-
lowed application of the galvanic stimulus.
The lower end of the cord was then elevated with a hook,
and the surface of the anterior columns was irritated by the
needle and by galvanism. The invariable effect was con-
GENERAL PROPERTIES OF THE SPINAL CORD. 277
vulsive movements in the lower extremities, without pain.
The same irritation was applied to the deep portions of the
anterior columns with like results ; i. e., convulsive move-
ments in the lower extremities, following the irritation im-
mediately.
The above-mentioned phenomena were fully verified by
repeated experiments, and the animal was then killed by
section of the medulla obloiigata.
The general movements accompanied by evidences of
pain were readily distinguishable from the local convulsive
movements with no pain.
This experiment fully confirms the observations of Chau-
veau with regard to the posterior columns, but shows, in
opposition to Chauveau, that the anterior columns are ex-
citable, both at the surface and in the deep portions. The
recent observations of Yulpian are also opposed to the re-
sults obtained by Chauveau with regard to the antero-lat-
eral columns. From a number of carefully-executed experi-
ments, Yulpian draws the following conclusions :
" 1 . The gray substance is absolutely inexcitable.
"2. The anterior fasciculi possess a certain degree of
motor excitability.
"3. There is no doubt that the posterior fasciculi are
very excitable. They are sensitive and excito-motor if the
cord be left intact, and simply excito-motor if the cord be
divided transversely and separated from the encephalon. It
is the same, but to a less degree, in that portion of the lat-
eral fasciculi contiguous to the posterior fasciculi." 1
In the face of definite and positive experiments showing
the excitability of certain portions of the cord, it is impos-
sible to accept the purely negative results obtained by Chau-
veau and others. This remark applies to recent experi-
ments made by Huizinga, carrying out the observations of
Yan Deen, in which he assumes to show that the anterior
1 YULPIAX, Lemons sur la physiologic generate et comparee da systeme nerveitx,
Paris, 1866, p. 362.
278 NERVOUS SYSTEM.
columns are not excitable, even near the roots of the nerves ;
and that when convulsive movements follow galvanization
near the roots, this is due to an extension of the current to
the roots themselves.1
As the result of the most definite and reliable experi-
ments of others, bearing upon the question of the properties
of the cord, and of our own observations, we have arrived
at the following conclusions :
The gray substance is probably inexcitable and insensible
under direct stimulation.
The antero-lateral columns are insensible, but are excita-
ble both on the surface and in their substance ; i. e., direct
stimulation will produce convulsive movements in certain
muscles, which movements are not reflex and are not attend-
ed with pain. The lateral columns are less excitable than
the anterior columns.
The surface, at least, of the posterior columns is very
sensitive, especially near the posterior roots of the nerves.
The deep portions of the posterior columns are probably in-
sensible, except very near the origin of the nerves.
The above conclusions refer only to the general proper-
ties of different portions of the cord, as shown by direct
stimulation, in the same way that we demonstrate the gen-
eral properties of the nerves in their course. In all proba-
bility, the fibres in the white and gray substance of the cen-
tral nervous system conduct motor stimulus from the brain
and sensory impressions to the brain, while they are them-
selves insensible and inexcitable under direct stimulation.
The physiological action of the cord as a conductor, one of
the most interesting and important of its functions, will be
fully considered in another chapter.
1 HUIZINGA, Die Unerregbarkeit der vorderen RucJcenmarkstrange.—Archiv
fur die gesammte Physiologic, Bonn, 1870, Bd. Hi., S. 81, et seq.
CHAPTER X.
ACTION OF THE SPINAL CORD AS A CONDUCTOR.
Transmission of motor stimulus in the cord — Decussation of the motor conduct-
ors of the cord — Decussation at the medulla oblongata — Decussation of the
motor conductors in the cervical portion of the cord — Transmission of sen-
sory impressions in the cord — The white substance of the posterior columns
does not conduct sensory impressions — Action of the gray matter as a
conductor— Probable function of the cord in connection with muscular
coordination — Decussation of the sensory conductors of the cord — Summary
of the action of the cord as a conductor.
IN treating of the functions of the spinal cord, both as a
conductor and as a nerve-centre, we shall endeavor to discuss
those facts only which are, it is to be hoped, either defini-
tively settled, or are in accordance with what is at present
known in anatomy, physiology, and pathology. The litera-
ture upon this portion of our subject is so extended and
diffuse, that a full, critical analysis of the different experi-
ments and views that have been presented since the obser-
vations of Magendie, in 1823, would inevitably complicate
and confuse our description. "We shall give citations, how-
ever, which will enable the reader to refer readily to the
most reliable historical and controversial discussions upon
this subject.1
1 Longet, in his treatise on physiology, gives a tolerably complete historical
account of the numerous experimental researches concerning the functions of
the cord as a conductor ( Traite de physiologic, Paris, 1869, tome iii., p. 338, et seq.\
The writings upon this subject by Brown-Sequard are very voluminous, and are
scattered through numerous periodical publications, while many of his papers
are controversial, and are reiterations of experiments and views previously pub-
280 NERVOUS SYSTEM.
Transmission of Motor Stimulus in the Cord. — The
antero-lateral columns of the cord, both the white and the
gray substance, are entirely insensible to direct irritation,
and conduct the motor stimulus from the centres to the
periphery. This statement may be accepted, as the result
of positive demonstration, with very little qualification.
If the posterior columns of the cord be divided or even
removed for a certain length, the animal retains the power
of voluntary motion intact. It is supposed by Dr. Brown-
Sequard that the white substance of the antero-lateral col-
umns, in addition to its motor properties, takes a slight but
well-defined part in the transmission of sensory impressions,
and this idea is based upon experiments which seem to show
that slight sensibility remains in the lower extremities after
section of the posterior columns.1 Such experiments, how-
ever, must be accepted with a certain degree of reserve, in
view of the great difficulty of dividing the columns sepa-
rately. If the white substance of the antero-lateral columns
take any part in the conduction of sensory impressions, it is
slight and unimportant. On the other hand, if the antero-
lateral columns of the cord be divided on both sides, the
power of voluntary motion is lost absolutely in all parts sup-
plied with nerves coming from the cord below the section.
It would be an interesting point to determine positively
the relative importance of the white and the gray substance
of the anterior columns in the transmission of motor stimu-
lus ; but this has thus far been impossible. We cannot with
certainty divide the gray matter of the anterior columns
completely and leave the white substance intact, nor can we
divide the white substance without injuring the gray. As
far as experiments go, however, they seem to show that
lished. A list of his most important memoirs, with a short account of his ex-
periments and conclusions, is given in the Journal de la physiologic, Paris, 1862,
tome v., p. 641, et seq.
1 BROWN-SEQUARD, JErcperimces montrant que les cordons anterieurs de la moelle
epinere servent d la transmission des impressions sensitives. — Journal de la physi-
ie, Paris, 1858, tome i., p. 809.
MOTOR CONDUCTION IN THE SPINAL COED. 281
transmission is not effected exclusively by the white sub-
stance, but that the gray matter plays an important part in
this function.1 "We shall refer, farther on, to the action of the
gray substance in the transmission of sensory impressions.
It is evident, from anatomical facts as well as from the
results of direct experimentation, that the fibres of conduc-
tion of motor stimulus pass from the brain to the anterior
roots of the nerves, through the spinal cord, from above
downward, and that there is no other medium for the trans-
mission of the will to the muscles. Wherever the cord
be divided, all the muscles supplied by nerves given off be-
low the section are paralyzed. From the brachial enlarge-
ment of the cord, nerves of motion pass to the superior ex-
tremities, and the inferior extremities are supplied mainly
by nerves coming from the lumbar enlargement. The di-
rection of these motor fibres in the cord itself has only
been elucidated by experiments upon living animals. If the
anterior columns alone be divided in the dorsal region, there
is almost complete paralysis of the lower extremities. If the
lateral columns be divided in this situation, without injuring
the anterior columns, voluntary movements of the lower ex-
tremities are diminished, but are not abolished. If the an-
terior columns be divided high up in the cervical region,
there is a diminution in the voluntary movements, but by
no means so marked as when the section is made in the dor-
sal region ; but if the lateral columns be divided in the upper
cervical region, the paralysis is almost or quite complete.2
The experiments just cited clearly show that the situa-
tion of the chief motor conductors of the cord is different in
the dorsal and in the cervical region. In the dorsal region,
while conduction of the motor stimulus takes place through
fibres contained both in the anterior and in the lateral
1 YULPIAN, Lemons sur la physiologie generate et comparee du systeme nerveux,
Paris, 1866, p. 369.
2 BROWX-SEQUARD, Physiology and Pathology of the Central Nervous System,
Philadelphia, 1860, p. 46. VULPIAN, Systeme nerveux, Paris, 1866, p. 370.
282 NERVOUS SYSTEM.
columns, the transmission is mainly through the anterior
columns, the lateral columns being much less important.
In the cervical region, the conditions are reversed, tad the
conduction takes place chiefly by means of the lateral col-
umns. Passing from above downward, therefore, the motor
fibres are situated in the cervical region mainly in the lateral
columns ; but progressively, as they pass through the dorsal
and the lumbar portions of the cord, these fibres change
their location and are found chiefly in the anterior col-
umns.
llecent observations have not sustained the old idea that
the lateral columns of the cord contain fibres which preside
specially over the movements of the thorax. The experi-
ments of Yulpian upon this point are conclusive. If the
lateral column be divided on one side at about the third or
fourth cervical vertebra, there is considerable enfeeblement
of the muscles of the thorax upon the corresponding side,
but there is also partial loss of power in the limbs, which is
more marked in the anterior extremity. This diminution
in powrer in the thoracic muscles is such, that in ordinary
tranquil respiration, the side corresponding to the section
does not move ; but in difficult respiration, or in crying, the
movements are very marked.
Decussation of the Motor Conductors of the Cord. — Well-
established anatomical and pathological facts show conclu-
sively that there is a complete decussation of the motor con-
ductors of the cord ; so that the stimulus of volition gen-
erated in one lateral half of the brain always passes to the
opposite half of the body. If a lesion occur in the brain
upon one side, so as to produce total paralysis of motion, the
opposite side of the body is paralyzed, while voluntary mo-
tion is absolutely intact on the side corresponding to the
injury. In the anterior pyramids of the medulla oblongata,
1 VULPIAN, Systeme nerveux, Paris, 1866, p. 371.
MOTOE COXDUCTIOJr IN" THE SPINAL CORD. 283
the decnssation of the fibres is easily demonstrated ana-
tomically. In view of these facts, concerning which there
is no difference of opinion, it only remains to show by
physiological experiments that decussation actually takes
place at the medulla oblongata, and to submit to the same
method of inquiry the following important question : Assum-
ing that crossing of motor fibres takes place at the medulla,
is this the sole seat of decussation of these fibres, or does it
also exist in certain portions of the cord below ?
The question of decussation at the medulla oblongata is
easily answered. In the first place, we have the crossed ac-
tion in hemiplegia and the easy anatomical demonstration
of the decussating fibres. The experimental confirmation
of these facts is not so simple, for the reason that animals
survive operations upon the medulla oblongata for a very
short time. As far as can be learned, however, from the
latter mode of inquiry, the conclusions drawn from anatomy
and pathology are fully sustained. If the medulla be ex-
posed in a living animal, and " if a section is made longitu-
dinally just at the place of the decussation of the anterior
pyramids, so as to divide completely all of the decussating
elements, we find that, although the animal lives some time
after the operation, it has no voluntary movement at all in
any of the limbs, which are almost always the seat of con-
vulsions." l
The question of decussation of motor fibres in the cord
itself is one which can be settled only by physiological ex-
periments, as the course of the decussating fibres, if they
exist, cannot be demonstrated anatomically. It is remark-
able that Galen submitted this point to experimental inves-
tigation, by dividing the cord longitudinally in the median
line in the lumbar region. This operation was not followed
by loss of voluntary power in the lower extremities, show-
ing that the motor fibres do not cross the median line, at
1 BROWN-SEQUARD, Physiology and Pathology of the Central Nervous System,
Philadelphia, 1860, p. 49.
284 NERVOUS SYSTEM.
least in this portion of the cord.1 Recent experiments upon
the cervical portions of the cord show that there is a very
slight decussation of motor fibres in this situation. The first
observations pointing to this conclusion are those of Brown-
Sequard. " There is always, even in mammals, after a trans-
versal section of the whole or a lateral half of the spinal cord,
at least some appearance of voluntary movements in the side
of the injury, and always also a diminution of voluntary move-
ments in the opposite side ; so that, in animals, there seems
to be in the spinal cord a decussation of a few of the volun-
tary motor conductors. As there seems to be no such decus-
sation in man, at least according to several pathological facts,
we shall not insist upon its existence in animals." 2
Yan Kempen has repeated and extended the very re-
markable experiment of Galen, with the most satisfactory
rosults. This observer made a median, longitudinal section
of the cord in dogs and rabbits, at the site of the fifth, sixth,
and seventh cervical vertebrae. " This experiment was fol-
lowed by partial paralysis of voluntary movements in the
posterior extremities, so that the animal thus operated upon
moved the posterior limbs and was able to change his posi-
tion, without, however, being able to raise himself." 3
As there is some difference in the results of observations
upon different animals, and as decussating motor fibres have
never been demonstrated in man, it is impossible to apply
the above experiments without reserve to the human sub-
ject ; but they show, nevertheless, that, in mammals, the
motor columns of the cord probably do not decussate in the
1 GALENUS, De Anatomicis Administrationibm, Liber viii., Cap. vi. — Opera
omnia, Lipsiae, 1821, tomus ii., p. 683.
These remarkable experiments must have been made in the latter half of the
second century, as Galen was born in 131, and died about the year 200.
2 BROWN-SEQUARD, Physiclogy and Pathology of the Central Nervous System,
Philadelphia, 1860? p. 48.
8 VAN KEMPEN, Experiences physiologiques sur la transmission de la semibilite
et du mouvement dans la moelle epinere. — Journa7 de la physiologic, Paris, 1 859,
tome ii., p. 528.
SENSOKY CONDUCTION IN THE SPINAL CORD. 255
dorso-lumbar region ; that partial decussation occurs in the
cervical region ; and that1 the decussation is completed in
the anterior pyramids of the medulla oblongata.
Transmission of Sensory Impressions in the Cord. —
There is very little room for discussion concerning what is
positively known with regard to the transmission of sensory
impressions in the cord, though there are some portions of
its structure, the action of which in conduction is still ob-
scure. Early in the physiological history of this portion of
the nervous system, Longet made a number of experiments,
which seemed to show that the posterior columns of the cord
were the conductors of sensory impressions to the brain, and
that the antero-lateral columns transmitted the motor stim-
ulus. These have been already referred to in connection
with the properties of the cord. They were made by apply-
ing a stimulus directly to the cord itself. Longet discredited
observations made by dividing different portions of the cord,
for the reason that he supposed that the mere operation of
exposing the cord and of removing the dura mater was
followed by a depression of the nervous action sufficient to
render the evidences of sensibility in the lower extremities
scarcely appreciable.1 The conclusions drawn from these
experiments were at first accepted by nearly all physiologi-
cal writers, and it was generally admitted that the transmis-
sion of sensory impressions was effected solely by the pos-
terior columns. It was found that the gray matter of the
cord was both insensible and inexcitable, and the conduction
was supposed to take place exclusively through the white
substance. The views of Longet were in direct opposition
to those of Bellingeri, who claimed, in 1823, to have demon-
strated by experiment, that sensory impressions were con-
veyed to the brain exclusively by the gray substance of
the cord, and that sensibility persisted in the lower ex-
1 LONGET, Anatomic et physiologic du tysteme nerveux, Paris, 1842, tome i.,
p. 276.
286 NEKVOUS SYSTEM.
trcmitics after complete section of the posterior white col-
umns.1
At the time the above-mentioned experiments were
made, our knowledge of the properties of the cord was very
incomplete, and it was difficult to understand how any of
its fibres could conduct sensory impressions and yet be in-
sensible to direct stimulation ; but now we know that the
gray matter does act as a conductor, and yet it is certainly
insensible. The simple questions now to be determined are
the following :
1. Does or does not the white substance of the posterior
columns of the cord conduct sensory impressions to the
brain ?
2. Does the entire gray substance of the cord act as a
conductor of sensation ?
3. Do both the gray matter of the cord and the white
substance of the posterior columns act as conductors, or
does either one act to the exclusion of the other ?
These questions may now be considered as definitively
answered by the most positive and unmistakable results of
experiments upon living animals, which, while they render
the precise function of the white substance of the posterior
columns a matter of conjecture, leave no doubt with regard
to t!he parts of the cord which act as conductors of sensory
impressions. This statement is based upon the researches
of Brown-Sequard, whose experiments upon this subject
have been often confirmed and never successfully contra-
dicted.
The experimental answer to the first question is capable
of but one construction. If the white substance of both
posterior columns be divided, the sensibility of the posterior
extremities is not diminished, at least as far as can be shown
1 BELLINGERT, De Medulla, Spinali Nervisgiie ex ea prodeuntibus, Annolationes
Anatomico-Physiologicce, Lectce a die Sjanuarii 1822 ad ZQjanuarii 1823, p. 237 ;
Experimenta Physiologica in Medullem Spinalem habita, Lecta die 13 junii 1824,
p. 311;' and LONGET, op. cit., tome iii., p. 341.
SENSOEY CONDUCTION IN THE SPINAL COKD. 287
by experiments upon animals, in which these points are al-
ways difficult of determination. On the other hand, if every
portion of the cord be divided except the posterior columns,
sensibility is completely lost in the parts below the section.
The accuracy of these results cannot be called in question,
especially when controlled by experiments showing the con-
ducting properties of the gray substance of the cord ; and
they show that, whatever may be the functions of the poste-
rior white columns, they do not serve as conductors of sen-
sory impressions.1
The second question admits of an equally positive an-
swer from the results of experimental inquiry. If the entire
substance of the cord, except the posterior columns of white
matter, be divided transversely, as we have just seen, sensi-
bility is abolished in all parts below the section ; but, as we
have stated in treating of the transmission of motor stimu-
lus by the cord, voluntary motion is also destroyed.11 Ex-
periments show, farthermore, that sensory impressions are
conveyed exclusively by the gray substance. " If the ante-
rior, the lateral, and the posterior columns of the spinal cord
1 The experiments by Brown-Sequard, which have led to the above conclu-
sion, are of the most positive and satisfactory character (Physiology and Pathol-
ogy of the Central Nervous System, Philadelphia, 1860, p. 19), and have been
repeatedly confirmed by himself and other observers, among the most promi-
nent of whom are Yulpian and Philipeaux (VULPIAX, Systeme nerveux, Paris,
1866, p. 373). The most important experiments in opposkion are those of
Schiff, quoted and adopted by Longet, by which Longet endeavors to prove that
the posterior columns are conductors of the tactile sense (LONGET, Traite de
physiologic, Paris, 1869, tome iii., p. 353). In these experiments, the antero-
lateral columns were divided, and the animal was afterward enfeebled by a copi-
ous haemorrhage. Upon pinching the tail, the animal gave evidence of sensa-
tion, but suffered no pain, even when the sciatic nerve was bruised or torn. In
these observations, it was not shown that the entire gray substance was divided,
and the experiments after copious haemorrhage were certainly not made under
strictly physiological conditions. It is well known, also, that if a small portion
of gray matter be undivided, there is conduction of sensory impressions. In all
of Brown-Sequard's experiments, the exact h'mits of the sections of the cord
were ascertained by subsequent examination of the parts hardened in alcoboL
8 See page 280.
119
SDICAL *
f Y r> r> • T^^.r
288 NEKVOUS SYSTEM.
are divided transversely, at the dorsal region, one set at one
place, another at a distance of one or two inches, and the
third also at the same distance from the second, so that the
only channel of communication between the posterior limbs
and the sensorium is the gray matter, of which, however,
several parts have, unavoidably, been divided (such as the
anterior and the posterior gray cornua, and also more or less
of the central gray matter), we find that the posterior limbs
are still sensitive, though evidently less than in the normal
condition."
It is impossible to divide the gray matter of the cord
alone, without injuring, more or less, the white substance ;
but when the gray matter is divided with very slight injury
of the white substance, sensibility in the parts below the
point of section is totally destroyed.3 As regards the part
of the gray substance specially concerned in the transmis-
sion of sensory impressions, the results of experimental in-
vestigation have not been so definite ; but Browii-Sequard
is of the opinion that the transmission takes place chiefly in
the gray matter surrounding the central canal, while it may
also occur to some extent in other portions.3
The answer to the third question is deduced from the
answers to the first two. The gray matter and the white
substance of the cord do not participate in the transmission
of sensory impressions, this being effected by the gray sub-
stance, especially its central portion, to the exclusion of the
white.
The precise office of the posterior white columns of the
cord is still a matter of conjecture. If these parts be insen-
sible, except on the surface and near the posterior roots of
the nerves, and if they take no part in the transmission of
sensory impressions to the brain, which seems to have been
conclusively proven, what is their function ?
1 BROWN-SEQUARD, Physiology and Pathology of the Central Nervous System,
Philadelphia, 1860, p. 22.
8 VULPIAN, Systeme nerveux, Paris, 1866, p. 374. 3 Op. cit., p. 23.
MTJSCITLAR COORDINATION. 289
The anatomical relations of the posterior white columns,
the results of experiments upon living animals, and certain
well-marked pathological phenomena, point very strongly to
a connection between these columns and the coordination
of muscular movements.
Probable Function of the Cord in Connection with Mus-
cular Coordination. — Anatomists have not been able to trace
satisfactorily the direction of all of the fibres contained in the
posterior columns ; but it is probable that at least some of
these fibres serve as longitudinal commissures, and connect
together the nerve-cells, extending for a greater or less dis-
tance both upward and downward in the cord. This ana-
tomical arrangement is rendered probable chiefly by the re-
sults of experiments.
If the posterior columns be completely divided, by two or
three sections made at intervals of from three-fourths of an
inch to an inch and a quarter, the most prominent effect is
a remarkable trouble in locomotion, consisting in a want of
proper coordination of movements. These important ex-
perimental results were obtained by Yulpian.1
In the remarkable disease known under the name of
locomotor ataxia,2 there is a very peculiar condition of the
muscular system, in which, while the power of the muscles
is but slightly diminished, the movements of progression
show great deficiency in coordinating power, frequently at-
tended with more or less disturbance in the sensibility of the
parts affected. These symptoms are associated with struc-
tural disease of the cord, limited to the posterior columns
and the posterior roots of the spinal nerves.
Many years ago, before locomotor ataxia had been gener-
ally recognized by pathologists, Todd made the following re-
markable statement with regard to the posterior columns :
1 YULPIAX, Systeme nerveux, Paris, 1866, p. 381.
8 For a description of this disease, see, HAMMOND, Diseases of the Nervous
System, New York, 1871, p. 484, et seq.
290 NERVOUS SYSTEM.
"I have long been impressed with the opinion, that the
office of the posterior columns of the spinal cord is very dif-
ferent from any yet assigned to them. Theyjnay be in part
commissural between the several segments of the cord, serv-
ing to unite them and harmonize them in their various ac-
tions, and in part subservient to the function of the cerebel-
lum in regulating and coordinating the movements necessary
for perfect locomotion." l Todd further states, that this view
is supported by the phenomena observed in cases of disease
" distinguished by a diminution or total loss of the power of
coordinating movements. ... In two examples of this va-
riety of paralysis, I ventured to predict disease of the poste-
rior columns, the diagnosis being founded upon the view^s
of their functions which I now advocate ; and this was found
to exist on post-mortem inspection ; and in looking through
the accounts of recorded cases in which the posterior col-
umns were the seat of lesion, all seem to have commenced
by evincing more or less disturbance of the locomotive pow-
ers, sensation being affected only when the morbid change
of structure extended to and more or less involved the pos-
terior roots of the spinal nerves." 3
It is only necessary to add that the views of Todd have
been in the main confirmed in the numerous cases of loco-
motor ataxia that have lately been so fully described by
pathologists ; and, from these facts, it is more than probable
that the posterior columns contain fibres connecting the dif-
ferent segments of the cord, and that they play an important
part in the coordination of muscular movements. The gen-
eral function of coordination will be again considered in con-
nection with the cerebellum.
Decussation of the Sensory Conductors of the Cord. — In
hemiplegia due to injury of the brain, the paralysis occurs
1 TODD, Cyclopcedia of Anatomy and Physiology, London, 1839-1847, vol. Hi.,
p. 721, Q, Article, Nervous System.
9 Op. «*., p. 721, R.
DECUSSATTOF OF, THE SENSORY CONDUCTOKS. 291
upon the side of the body opposite to the cerebral lesion.
The phenomena ordinarily observed are simply paralysis of
motion ; but in those cases in which both motion and sensa-
tion are abolished upon one side of the body, the lesion in
the brain is found to be upon the opposite side. It is evi-
dent, therefore, that there is a decussation of the conductors
of sensory impressions as well as of the conductors of the mo-
tor stimulus.
As early as 1822, Fodera made a longitudinal section of
the spinal cord in the lumbar region, exactly in the median
line. In this experiment, " sensation was destroyed, and in
part motion upon the two sides." * Inasmuch as in this sec-
tion it is only possible to divide the fibres, passing from one
lateral half of the cord to the other, it is evident that the
sensory conductors must decussate in the spinal cord itself.
As far as we know, this is the first experiment pointing to
the decussation of sensory fibres in the cord, the observations
of Galen, to which we have already referred, being limited
to the phenomena of motion.3
The next experiments bearing upon the decussation of
the sensory conductors in the cord are those of Yan Deen.
Among the numerous observations made upon the spinal
cord by this physiologist, are one or two in which he noted
the fact that, after section of one lateral half of the cord in
the frog, at the site to the third dorsal vertebra, " the animal
had no real loss of sensibility in the posterior extremity on
the side on which the half of the spinal cord had been cut." 3
Although Yan Deen did not distinctly state, as a conclusion
drawn from these observations, that there is decussation of
the sensory conductors in the cord, the fact of section of one
lateral half of the cord with no loss of sensation on the cor-
1 FODERA, Recherches experimentales sur le systeme nerveux, presentees d
T Academic des sciences, le 31 decembre, 1822. — Journal de phy&dogie, Paris, 1823,
tome ill, p. 199.
9 See page 284.
3 VAN BEEN, Traiies et decouvertes sur la physiologic de la moette epinere,
Leide, 1841, pp. 65, 92.
292 NERVOUS SYSTEM.
responding side of the body remains as one of the first ex-
perimental arguments in favor of the crossed action.
Experiments upon living animals as well as pathological
facts show that, after section or injury confined to one lateral
half of the cord, the general sensibility upon the correspond-
ing side of the body is very much exaggerated, producing a
condition of well-marked hypersesthesia. This remarkable
fact was distinctly noted by Fodera, in 1822: "Having di-
vided, in a Guinea-pig, the right superior column of the cord
in the middle of the dorsal region, the sensibility of the flank
and of the posterior extremity of the same side was more
exquisite than in every other part of the body, and it seemed
that the movements of the same extremity possessed greater
energy." ] This observation was confirmed, and the experi-
ments were very much extended, by Brown-Sequard.2 Cases
presenting the same phenomena have also been observed in
the human subject, when one side of the cord has been in-
vaded by disease.3
Physiologists are at a loss to explain the hypersesthesia
which follows section of the sensory conductors of the cord,
but the fact nevertheless remains. The exaggeration of sen-
sibility is not due to section of certain fibres, which might
be supposed to increase the impressibility of the remaining
fibres, for, as was shown by Yulpian, it is sufficient to prick
with a pin one of the lateral halves of the cord to observe
these remarkable phenomena.4 "With these few words, we
will leave the subject of hypersesthesia from injury to the
cord, and pass to the crossed action of its sensory con-
ductors.5
1 FODERA, Journal de physiologic, Paris, 1823, tome iii., p. 200.
2 BROWN-SEQUARD, Experimental Researches applied to Physiology and Pathol-
ogy, New York, 1853, p. 64, el al
3 BROWN-SEQUARD, Recherches sur la transmission des impressions de tad, de
chatouillement, de douleur, de temperature et de contraction (sens musculaire) dans
let moette epinere. — Journal de la physiologie, Paris, 1863, tome vi., p. 645.
4 VULPIAN, Systeme nerveux, Paris, 1866, p. 388.
5 For further experiments showing the effects of transverse section of the
DECUSSATIOX OF THE SENSORY CONDUCTOES. 293
In treating of the cord as a conductor of sensory impres-
sions, we have already shown that this function is performed
by the gray substance alone. "We have also seen, in connec-
tion with the phenomena of conduction of the motor stimu-
lus, that this is effected by the antero-lateral columns, which
do not act as sensoiy conductors, except by virtue of their
gray matter. As it is impossible to divide the gray matter
with certainty without injuring the white substance, and as
we are fully acquainted with the motor properties of the
cord, we are prepared to comprehend the effects upon con-
duction of sensory impressions which follow division of one
or the other lateral half. In our detail of experiments, we
will not consider the phenomena of hypersesthesia, but con-
fine ourselves to the loss or diminution of sensibility.
Brown-Sequard was the first to demonstrate decussation
of the sensory conductors in the cord itself ; and, although
his experiments upon this subject are almost innumerable,
and his writings, scattered, voluminous, and sometimes not
free from the obscurity due to unnecessary refinement and
elaborateness of detail, the main facts can be expressed in
a very few words ; and he may justly be said to have created
the physiology of the sensory conductors.
Brown-Sequard repeated the experiments of Galen and
of Fodera, dividing the cord longitudinally in the median
line, producing complete paralysis of sensation on both sides
in all the parts below the section. By this operation, if the
section had been made accurately in the median line, the
only fibres that could be divided were those passing from
one side of the cord to the other.
The second experimental proof of the decussation of sen-
sory fibres consists in transverse section of one or the other
of the lateral halves of the cord. If one lateral half of the
cord be divided, sensibility is abolished in the parts below
cord in its posterior portion, see, BROWN-SEQUARD, Nouvelles recherches sur la
physiologic de la moelle epinere. — Journal de la physiologic, Paris, 1858, tome i.,
p. 139.
294: NERVOUS SYSTEM.
the section upon the opposite side of the body. 'In an article
published in 1858, Brown-Sequard details very succinctly an
experiment showing this fact, though his first experiments
were made in 1849.1 He denuded the cord in the lumbar
region in a vigorous dog, and made sections upon one side,
progressively deeper and deeper, from without inward.
When the section included about one-third of the lateral
half, the sensibility seemed slightly augmented upon the
opposite side. This section involved only a part of the lat-
eral white column and a small portion of the anterior cornu
of gray matter. When the section was extended so as to
involve about two-thirds of the lateral half, the sensibility
was notably diminished upon the opposite side. When the
section extended to the median line, the sensibility was very
much diminished ; and when it extended just beyond the
median line, it was entirely abolished upon the opposite
side.2 These observations, and others of the same nature,
show conclusively that in the animals experimented upon,
at least, there is a decussation of the greatest part of the
sensory conductors in the cord itself.
The course of the fibres in their decussation is indicated
by further experiments, which show that the sensitive fibres
from the posterior roots of the nerves " pass along the poste-
rior columns only a little way, and leave them to enter the
central gray matter." ' It is undoubtedly in this gray sub-
stance that they pass from one side to the other, probably
through the cell-prolongations. The fact that the fibres pass
in the cord a short distance before they decussate, and that
they pass downward as well as upward, is well shown by the
following experiment :
" If we divide transversely a lateral half of the spinal
1 See list of works, in the Journal de la ph^siologie, Paris, 1862, tome v.,
p. 646, No. 44.
2 BROWN-SEQUARD, Nouvelles recherches sur la physiologic de la moelle epinere.
— Journal de la physiologie, Paris, 1858, tome L, p. 139, et seq.
8 BROWN-SEQUARD, Physiology and Pathology of the Central Nervous System.
Philadelphia, 1860, p. 25.
SUMMARY -OF THE SPINAL COED. 295
cord in two places, so as to have three pairs of nerves be-
tween the two sections, we find that the middle pair has
almost the same degree of sensibility as if nothing had been
done to the spinal cord, while the two other pairs have a
diminished sensibility, the upper one particularly in its upper
roots, and the lower one in its lower roots ; which facts seein
to show that the ascending fibres of the upper pair, and the
descending fibres of the lower one, have been divided before
they had made their decussation.
If there is only one pair of nerves between two sections,
its sensibility is almost entirely lost, as then the transversal
fibres are almost alone uninjured (most of the ascending and
descending being divided), which fibres are employed for
reflex action, and hardly for the transmission of sensitive
impressions." l
The experimental facts just cited conclusively show de-
cussation of sensory conductors in the cord in the animals
operated upon, and this has been sufficiently confirmed by
other experimenters to render the fact certain. It is possi-
ble that the decussation may not be so complete in some
other classes of animals, which would account for the results
obtained by those who have denied decussation ; but cases
of disease of the cord in the human subject all go to show
that the crossed action is complete in man.
/Summary of the Action of the Spinal Cord as a Conductor.
The antero-lateral columns of the cord, comprising that
portion included between the anterior median fissure and the
origin of the posterior roots of the nerves, are insensible to
direct irritation, and serve as conductors of the motor stimu-
lus from the brain to the anterior roots of the nerves. If
these columns be divided, voluntary motion is lost in all
parts below the section. If the rest of the cord be divided,
leaving the antero-lateral columns intact, the power of volun-
1 BROWX-SEQUARD, Central Nervous System, Philadelphia, 1860, p. 36.
296 NEKVOUS SYSTEM.
tary motion remains. Throughout the greater part of the
cord, this action is direct, and division of the antero-lateral
columns on one side produces paralysis of motion on the cor-
responding side of the body. There is a decussation of the
motor fibres at the medulla oblongata, and a partial decussa-
tion in the cord itself in the upper cervical region. In the
dorsal region and below, the motor conducting fibres are
situated chiefly in the anterior columns ; but in the cervical
region, these fibres pass to the sides and are contained chiefly
in the lateral columns. The conduction of motor stimulus
is probably not effected exclusively by the white substance,
but is transmitted in part by the gray matter.
The gray substance of the cord serves as the medium of
transmission of sensory impressions to the brain. This is
effected chiefly by the gray matter surrounding the central
canal, but it may take place to some extent in other portions.
If the entire gray matter be divided, with but slight injury
to the white substance, sensation is lost in all parts situated
below the section. The white substance does not conduct
sensory impressions to the brain, either in the antero-lateral
or the posterior columns. The most probable function of
the white substance of the posterior columns is to unite
the different segments of the cord together by longitu-
dinal commissural fibres ; and this portion of the cord has
an important influence in coordinating the muscular move-
ments.
The sensitive nerve-fibres from the posterior roots of the
spinal nerves pass in the cord for a short distance upward
and downward. They then penetrate the gray matter, and
decussate throughout the entire length of the cord. Divis-
ion of one lateral hah0 of the cord is followed by complete
paralysis of motion on the corresponding side of the body in
all parts below the section ; anaesthesia in all parts below the
section, on the opposite side of the body ; and hypersesthesia
in the parts below the section, upon the corresponding side
of the body.
SUMMARY-. OF THE SPIXAL CORD. 297
The anatomical points bearing upon the physiological
action of the cord are the following :
The fibres from the anterior roots penetrate the anterior
gray cornua directly and are in immediate connection with
the prolongations of the motor cells. The motor cells also
have prolongations which pass to the brain in the white sub-
stance. The motor fibres are thus directly connected with
the cellular elements of the cord, the elements probably con-
cerned in reflex movements, and the cells are in connection
with conducting fibres to the brain.
The fibres from the posterior roots take several directions.
Some of them pass to the gray substance. A portion passes
to the posterior columns, some extending upward and others
downward. The decussation, which is rendered certain by
physiological experiments, has not been satisfactorily fol-
lowed by anatomists. It undoubtedly takes place in the gray
substance, probably in part by a crossing of the fibres them-
selves, and in part by a crossing of prolongations from the
cells with which certain fibres from the posterior roots are
connected.
CHAPTEE XI.
.
ACTION OF THE SPINAL COED AS A NEEVE-CEXTEE.
Movements in decapitated animals — Definition and applications of the term
" reflex " — Reflex action of the spinal cord — History of the discovery of
so-called reflex action — Question of sensation and volition in frogs after
decapitation — Character of movements following irritation of the surface
in decapitated animals — Dispersion of impressions in the cord — Conditions
essential to the manifestation of reflex phenomena — Exaggeration of reflex
excitability by decapitation, poisoning with strychnine, etc. — Reflex phe-
nomena observed in the human subject.
IT has long been known that decapitation of animals does
not immediately arrest muscular action ; and the movements
observed after this mutilation present a certain degree of
regularity, and, of late years, have been shown to be in ac-
cordance with well-defined laws. Under these conditions,
the regulation of such movements is effected through the
spinal cord and the nerves connected with it. If an animal be
decapitated, leaving only the cord and its nerves, there is no
sensation, for the parts capable of appreciating sensation are
absent ; nor are there any true voluntary movements, as the
organ of the will is destroyed. Still, in decapitated animals,
the sensory nerves are for a time capable of conducting im-
pressions, and the motor nerves can transmit a stimulus to
the muscles ; but the only part capable of receiving an im-
pression or of generating a motor stimulus is the gray matter
of the cord. If, in addition to the Removal of all of the en-
cephalic ganglia, the cord itself be destroyed, all movements
of voluntary muscles are abolished, except as they may be
THE SPESTAL COED AS A NEEVE-CEXTEE. 299
produced by direct stimulation of the muscular tissue or of
individual motor nerves.
We must regard the gray matter of the brain and spinal
cord as a connected chain of ganglia, capable of receiving
impressions through the sensory nerves, and of generating
the so-called nerve-force. The great cerebro-spinal axis,
taken as a whole, has this general function ; but some parts
have separate and distinct properties," and can act indepen-
dently of the others. The cord, regarded as a conductor,
connects the brain with the parts to which the spinal nerves
are distributed. If the cord be separated from the brain in
a living animal, it may act as a centre, independently of the
brain ; but the encephalon has no communication with the
parts supplied with nerves from the cord, and can only act
upon the parts which receive nerves from the brain itself.
It has been pretty clearly shown that when the cord is
separated from the encephalon, an impression made upon
the general sensory nerves is conveyed to its gray substance,
and is transformed, as it were, into a stimulus, which is
transmitted to the voluntary muscles, giving rise to certain
movements, independently of sensation and volition. This
impression is said to be reflected back from the cord through
the motor nerves ; and the movements occurring under these
conditions are called reflex. As they are movements excited
by stimulation of sensory nerves, they are sometimes called
excito-motor.
The term reflex may properly be applied to any genera
tion of nerve-force which occurs as a consequence of an im-
pression received by a nerve-centre ; and reflex phenomena
are by no means confined to the action of the spinal cord.
The movements of the iris are reflex, and yet they take place
in many instances without the intervention of the cord.
The movements of respiration are reflex, and these are pre-
sided over by the medulla oblongata. Movements of the
intestines and the involuntary muscles generally are reflex,
and they involve the action of the sympathetic system of
300 NEKVOUS SYSTEM.
nerves. Impressions made upon the nerves of special sense,
as those of smell, sight, hearing, etc., give rise to certain
trains of thought. These involve the action of the brain ;
still they are reflex. In this last example of reflex action, it
is sometimes difficult to connect the operations of the mind
with external impressions as an exciting cause; but it is
evident, from a little reflection, -that this is often the case.
This fact is illustrated "by operations of the brain which take
place, as it were, without consciousness, as in dreams. It
has been clearly shown that a particular direction may be
given to the thoughts during sleep, by impressions made
upon the sense of hearing. A person sleeping may be made
to dream of certain things, as a consequence of hearing pe-
culiar noises. Examples of this kind of mental reflex action
are sufficiently numerous and well authenticated.1
From the above considerations, it is evident that the
term reflex may be properly used in connection with many
phenomena involving the action of the sympathetic system
and of the brain ; but it is generally understood as applying
especially to involuntary movements, occurring without con-
sciousness, as the result of impressions made upon the affe-
rent nerves, and involving the independent action of the
spinal cord.
Reflex Action of the Spinal Cord.— In 1832 and 1833,
Marshall Hall described minutely the movements which take
place in decapitated animals as a consequence of stimulation
of the sensory nerves, and formularized these phenomena
under the head of " the reflex function of the medulla ob-
longata and medulla spinalis." a Since this publication, a
new interest has been attached to the writings of some of
the older physiologists, in which reflex action, as it is now
1 For numerous instances of peculiar dreams referable to external impres-
sions received during sleep, see, HAMMOND, Sleep and its Derangements, Philadel-
phia, 1869, p. 12Y, et seq.
2 MARSHALL HALL, On the Reflex Function of the Medulla Oblongata and Me'
dulla Spinalis, London, 1833.
EEFLEX ACTION OF THE SPINAL COED. 301
understood, had been mentioned more or less definitely. In
the history of important advances in physiological knowl-
edge, it has often been the case • that discoveries have been
foreshadowed by the earlier writers ; and bibliographical re-
search shows that the literature of the cord as a nerve-centre
forms no exception to this, which is almost the rule. Some
of the allusions to the cord as a centre of reflex action,
made anterior to 1833, are vague and indefinite'; but, on
the other hand, certain excito-motor actions were very ac-
curately described, as early as 1812. Marshall Hall grouped
and classified these phenomena, and showed their relations
to the cord as an independent centre ; but, as we shall see,
he has no claim to the title of the discoverer of reflex action,
and his experiments presented little that was really new.
AVhytt, in his work on the " Vital and other Involuntary
Motions," states that the involuntary and mixed motions
proceed from a stimulus, the latter being partly, and the
former not at all, under the power of the will ; 1 and, by a
stimulus, he means an impression made upon the sensory
nerves.
Prochaska, who wrote between 1778 and 179 7, states that
the sensorium commune extends to the medulla spinalis, and
that this " is manifest from the motions exhibited by decapi-
tated animals, which cannot take place without the consen-
tience and intervention of the nerves arising from the me-
dulla spinalis ; for the decapitated frog, if pricked, not only
withdraws the punctured part, but also creeps and leaps,
which cannot be done without the consensus of the sensorial
and motor nerves, the seat of which consensus must neces-
sarily be in the medulla spinalis — the remaining portion of
the sensorium commune." a He calls this " reflexion," and
speaks of it as taking place without consciousness, describing
many phenomena now familiarly known as reflex.
1 WHYTT, Works, Edinburgh, 1768, p. 170.
8 PROCHASKA, A Dissertation on the Functions of the Nervous System, Syden-
ham Society, London, 1851, p. 430.
302 NERVOUS SYSTEM.
Legallois published, in 1812, a remarkable memoir on
the principle of life. In this work, he details numerous ex-
periments, many of them on the nervous system, and of
great interest in connection with the present question. In
the rabbit, after division of the cord in the lumbar region,
Legallois showed that " sensation and voluntary motion con-
tinued to take place, even in the posterior extremities. But
there is no longer any connection in sensation or movement
between the anterior parts and the parts posterior to the
section of the cord ; that is to say that, if the tail or, in-
deed, one of the hind-feet be pinched, the entire posterior
parts are agitated, but the anterior parts seem to feel noth-
ing, and do not move." l
Passing over a few confirmatory observations by other
experimenters, we come to those of Fodera, in 1822. Fodera
states that " in wounds of the spinal cord, the animal suffers
pain and convulsions ; if it be divided transversely, there is
paralysis of the posterior parts, writh loss of sensation and
motion. But irritation applied below the section produces
agitation of the muscles to which the nerves derived from it
are distributed. The animal does not suffer pain, for it
has no consciousness of what takes place in these parts." 2
Again, Fodera says : " With regard to the spinal cord, com-
plete transverse section in birds does not in general en-
tirely paralyze the posterior extremities ; if we pinch the
foot, they withdraw it, although they suffer no pain from it ;
but if the spinal cord be entirely destroyed in the interior
of the vertebral canal, the paralysis is perfect." ! At about
the same time, Mayo described, even more definitely than
his predecessors, the reflex function of the cord, in the fol-
lowing words :
1 LEGALLOIS, Experiences sur le prindpe de la vie. — (Euvres, Paris, 1824, p. 80.
2 FODERA, RecJierches experimentales sur le systeme nerveuz, Presentees d
r Academic des sciences le 31 decembre, 1822. — Journal de la physiologic ', Paris,
1823, tome iii., p. 196.
3 Op. tit., p. 214.
REFLEX ACTION OF THE SPIXAL CORD. 303
" On the one hand, it is clear that an influence, inde-
pendent of the will, occasionally throws voluntary muscles
into action, as appears in tetanus and other spasmodic dis-
orders; and is shown remarkably in the physiological ex-
periment of irritating the skin on the lower extremities, after
the division of the spinal cord in the back, when the occur-
rence of action limited to the muscles of the inferior extremi-
ties, evinces that a connection exists, independently of the
will, between sentient surfaces and the action of voluntary
muscles. I have varied this experiment by dividing the
spinal cord at once in the neck and in the back, upon which
three unconnected nervous centres exist ; and the division
of the skin of either part (and especially at the soles of the
feet, in the two hinder portions) produces a convulsive action
of the muscles of that part alone. The same influence may,
then, possibly regulate the unconscious actions to which
these remarks relate." 1
The experiments of Marshall Hall, published in 1832
and 1833, are familiar to every physiologist, as supplying
nearly all of the omissions of the observers just cited. The
points which he assumed to have experimentally demon-
strated by his researches are as follows : A decapitated ani-
mal, the only part of the cerebro-spinal axis which remains
being the spinal cord, will make no movements, if complete-
ly protected from all external impressions. An impression
made upon the sensory nerves of a decapitated animal is
reflected by the cord, through the motor nerves, to the mus-
cles, and gives rise to reflex movements. If the cord be
destroyed, no movements follow stimulation of the surface.
If the centripetal and the centrifugal nerves be divided, no
reflex movements can take place. Experiments upon de-
capitated animals accord with the results of observations
upon acephalous foetuses, and in cases of complete paraplegia
from injury to the cord. All of the involuntary movements
1 MAYO, Anatomical and Physiological Commentaries, Number II., July, 1823,
London, 1823, p. 17.
120
304 NEKVOUS SYSTEM.
observed in the healthy body are explained by the theory of
reflex action.1 These observations of Marshall Hall were, in
the main, confirmed by Miiller, the year succeeding their
first publication ; 3 and, by some writers, the credit of the
discovery of the mechanism of reflex action is given to both
Miiller and Marshall Hall.
From the point of view which the present condition of
science enables us to take with regard to the reflex action
of the cord, we have to determine the accuracy of the obser-
vations of Marshall Hall, and to follow out the advances
that have been made by more recent observers. It is impor-
tant, as the first step in our inquiry, to ascertain the exact
condition of decapitated animals as regards their capacity
for muscular movements ; and upon this point there is some
difference of opinion. Marshall Hall thought that an ani-
mal, a frog, for example, after decapitation, was incapable
of any voluntary movement, or of any movement which did
not have, for its exciting cause, an external impression. "We
take the example of frogs, because these are the animals
most commonly used by experimenters.
All who have experimented upon frogs have seen them
jump about vigorously after decapitation ; and the question
whether these be spontaneous movements, so called, or an
excito-motor action, is more difficult to determine than
would at first sight appear. It would be unphilosophic to
assume that because the animal has been decapitated, the
movements are due to external impressions only, if we use
this as evidence against the possibility of spontaneous
movements under these conditions. The obvious necessity
of the argument is to remove all possibility of external im-
pressions, or of irritation of the cord itself. Upon this
1 MARSHALL HALL, Reflex Function of the Medulla Oblongata and Medulla
Spinalis, London, 1833 ; and, Memoirs on the Nervous System, London, 1837.
Marshall Hall states that his first publication appeared in the Proceedings of
the Zoological Society, in 1812.
2 MULLER, Elements of Physiology, translated by Baly, London, 1840, pp. 761,
J99.* The first edition of M tiller's work was published in Berlin, in 1833.
REFLEX ACTION OF THE SPINAL COED. 305
point we can only speak positively from our own experiments.
If a frog be decapitated, so as to leave only the spinal cord
intact, if we wait for from one to three minutes until the
effects of the shock and local irritation have subsided, if we
then, when the animal has become perfectly quiet, cover it
with a bell-glass, and finally, if we remove all possibility of
jarring the table on which the animal is placed, there is no
movement of muscles. In making an experiment of this
kind, we occasionally see movements which are due to a
very feeble impression, such as a breath of air, or a jar from
the street, but which is perfectly evident to the observer ;
and, when a movement is once made, this gives rise to an-
other impression, and thus, successive actions of the muscles
may take place. The movements in jumping are so simple
that they seem, sometimes, under these conditions, to be vol-
untary. The effect of feeble excitations is also very marked
in animals poisoned with strychnine ; but, even here, we do
not have movements, unless an impression be first made
upon the sensory nerves. When we come to experiments
upon the mammalia, there can hardly be any question of this
kind ; for here, as the rule, no movements are observed after
the encephalic ganglia have been removed, unless the sen-
sory nerves be pretty strongly stimulated. Analogous phe-
nomena are observed in the lower extremities, in cases of
paraplegia in the human subject.
The next important question to determine is with regard
to the nature of movements excited by external stimulation
in decapitated animals, especially frogs ; for some of these
movements are so regular as to appear to be connected with
sensation and volition. The experiments of Pfliiger upon
this point are very remarkable. These have been repeatedly
confirmed, and there can be no doubt with regard to their
accuracy. Pfiiiger carefully removed from a frog the entire
encephalon, leaving only the spinal cord. He then touched
the surface of the thigh over the inner condyle with acetic
acid, to the irritation of which frogs are peculiarly sensitive.
306 NEBVOUS SYSTEM.
The animal thereupon rubbed the irritated surface with the
foot of the same side, apparently appreciating the locality of
the irritation, and endeavoring, by a voluntary effort, to re-
move it. The foot of this side was then amputated, and
the irritation was renewed in the same place. The animal
made an ineffectual effort to reach the spot with the ampu-
tated member, and, failing in this, after some general move-
ments of the limbs, rubbed the spot with the foot of the
opposite side.1 Although this experiment does not always
progress precisely in the manner described, it has succeeded
perfectly in so many instances as to lead some physiologists
to conclude that sensation and volition are not entirely abol-
ished by removal of the encephalon, at least in frogs.2
The remarkable phenomena just detailed are to be re-
garded from two points of view : first, with reference to
their bearing upon the question of the existence of percep-
tion and volition in the spinal cord of the frog ; and second,
the question of the application of these phenomena to the
physiology of the cord in man and the higher classes of ani-
mals. The conditions of the experiment in the frog are sim-
ply these : Instead of exposing the surface to a single and
instantaneous stimulation, the excito-motor effects of which
are observed as a direct response to the irritation, and im-
mediately cease, we have, by the application of acetic acid
to the surface, a prolonged impression upon the sensory
nerves, which, by virtue of the anatomical connections be-
tween the different parts of the cord, is proba'bly dispersed
throughout the entire spinal axis. That powerful impres-
1 PFLUGER, Die sensorischen Functionen des RuclcenmarTcs der Wirbelthiere,
Berlin, 1853, S. 124," et seq.
2 Observations of very much the same character as those of Pfliiger were
published by Patqn, in 1858. He refers to experiments showing the perceptive
power of the cord, by Dr. Dowler, of New Orleans, but does not allude to the
experiments of Pfliiger. (PATON, On the Perceptive Power of the Spinal Cord
as manifested by Experiments on Cold-blooded Animals. — North American Medico-
Chirurgical Review, Philadelphia, 1858, vol. ii., pp. 467, 703). These obser-
rations have been repeatedly confirmed by other physiologists.
REFLEX ACTION OF THE SPINAL CORD. 307
Bions may be thus dispersed, there can be no doubt, as we
shall see farther on. The phenomena under consideration
certainly point to an appreciation by the cord of the locality
of a powerful impression, and this could be manifested in an
animal only by an apparent muscular effort to reach the irri-
tated spot ; but we can hardly reason from this fact, that in
man and the higher animals, the spinal cord shares with the
brain the power of appreciating what we know as sensation
and of generating the stimulus of true voluntary movement.
If a sudden and very powerful painful impression be made
upon the surface in man under normal conditions, the hand
may be instantly applied to the affected part, apparently be-
fore we really appreciate the pain or have time to make a
distinct effort of the will ; but the connections between the
different parts of the cerebro-spinal axis do not permit us to
isolate the action of the cord. Certain it is that, in the higher
animals, after removal of the encephalon, and in experiments
upon decapitated criminals and patients suffering from para-
plegia, there is no evidence of true sensation or volition in
the spinal cord ; and in man and the higher animals, we
must regard all muscular movements which depend solely
upon the action of the cord as a nerve-centre as automatic
and entirely independent of consciousness and of the will.
It is easy to determine, by experiments to which we have
already incidentally alluded, that the muscular movements
dependent upon nervous action, occurring in decapitated
animals, are due to the action of the spinal cord as a nerve-
centre. In an animal in which the reflex phenomena are
very marked, as they are after decapitation, especially if the
animal be poisoned with strychnine or opium, all movements
cease immediately when the cord is destroyed. That the
gray matter of the cord is the part concerned as a centre in
the production of these phenomena, is probable, in view of
what we know with regard to the general functions and
properties of this substance ; and experiments have shown
that this is the fact. If, in a decapitated frog, we make a
308 NERVOUS SYSTEM.
longitudinal section of the cord in the median line, leaving
only a slight communication between the two sides, we may
sometimes succeed, by strongly irritating the skin of one leg.
in producing reflex movements, not only in the same leg,
but in the leg of the opposite side ; and it is reasonable to
suppose that the irritation is propagated from one side to
the other through the cells of the gray matter.1
The conditions essential to the manifestations of reflex
phenomena depending upon the action of the cord are very
simple and easily understood.
In the first place, it is necessary that one or more of the
posterior roots of the spinal nerves should be in communica-
tion with the cord, in order to conduct the impression to this
nerve-centre. If all of the posterior roots be divided, there
is no nervous communication between the periphery and the
centre, and no movements follow irritation of the surface.
When the excitability of the cord is exaggerated, as in poi-
soning by strychnine, a single posterior root is sufficient to
conduct an impression to the cord, which will give rise to
violent contractions of all the muscles.2 This is due to a dis-
persion of the impression, under these conditions of increased
excitability, from the single point of entrance of the poste-
rior root, throughout the cord. In animals that have been
simply decapitated, a similar dispersion of impressions may
also take place. If a comparatively feeble single impression
be made upon any part of the general surface, as the rule,
the subjacent muscles only are the seat of contraction ; but
if the impression "be more powerful, or if it be prolonged, as
when we apply a drop of acetic acid to any part of the skin
of a frog, this impression may be diffused throughout the
cord, producing contractions of the general muscular system.
We have already shown, in treating of the general properties
of the sensory nerves, that an impression made at any point
in the course of a nerve is conducted to the centre. Reflex
1 LONGET, Traiti de physiologie, Paris, 1869, tome Hi., p. 260.
* BERNARD, Systeme nerveux, Paris, 1858, tome i., p. 342.
BEFLEX ACTION OF THE SPINAL CORD. 309
movements may, consequently, be produced by stimulating
the sensory nerves in their course, or by irritating the poste-
rior roots of the spinal nerves.
TTe have already stated that the cord must retain its
anatomical integrity, in order to receive an impression made
upon the centripetal nerves, and transform it, as it were, into
a stimulus, which is reflected back by the motor nerves and
produces muscular contraction. It is also evident ' that the
motor nerves must retain their connection with the cord,
and be in a condition to conduct the stimulus reflected by
the cord to the muscles.
The reflex excitability of the spinal cord is increased to
a marked degree by separating this portion of the cerebro-
spinal axis from the encephalon, and the same is true for the
lower portion of the cord, when a section is made in the dor-
sal or the lumbar region. It is difficult to find an entirely
satisfactory explanation of this fact ; and the phenomena ob-
served under these conditions are, in this regard, like the
exaggerated sensibility of portions of the general surface
after section of certain columns of the cord. Setschenow
proposed, some years ago, the theory that the reflex excita-
bility of the cord under natural conditions was subject to a
moderating, or an inhibitory influence from the encepha-
lon ; and that this influence being absent in decapitated ani-
mals, the excitability of the cord, under these conditions,
seemed to be exaggerated.1 Whether this explanation be
accepted or not, the fact remains, that reflex phenomena
are more easily excited and are more marked in animals
after decapitation, than in the same animals, when the con-
nections between the cord and brain have not been de-
stroyed. In addition, Yulpian has shown that the excita-
bility is intense in proportion as the part of the cord con-
1 SETSCHENOW, Physiologische Studien uber die Hemmungsmechanismen fur
die Rfflexthatigkeit des Ruckenmarks im Gehirne des Frosches, Berlin, 1863 ; and,
SETSCHENOW UND PASCHTTTIN, Neue Versuche am Him und Riickenmark, Berlin,
1865.
310 NERVOUS SYSTEM.
cerned in the reflex phenomena is restricted; and, after
section of the cord itself, the most powerful and easily-ex
cited movements are produced when the division has been
made low down in the lumbar region. He has also shown
that simple puncture of the cord produces an exaggeration
of the reflex excitability, as well as hyperaesthesia.1
In experiments upon animals, the reflex phenomena are
greatly exaggerated in intensity in the tetanic condition pro-
duced by poisoning by opium or strychnine. Take, for
example, a frog decapitated and poisoned with strychnine.
No reflex movements occur unless an impression be made
upon the sensory nerves; but the faintest irritation, such as
a breath of air or a slight jar, throws the entire muscular
system into a condition of violent tetanic spasm. The same
phenomena are observed in cases of poisoning by strychnine,
or of tetanus, in the human subject. This fact is important
in its relations to the treatment of these conditions ; for it
is evident that, in such cases, the exhaustion due to the vio-
lent spasms may be moderated by carefully avoiding all un-
necessary irritation of the surface.
It was shown a number of years ago, by Longet, that the
inhalation of anaesthetic agents may abolish all of the ordi-
nary reflex phenomena.2 "Whether this be due to an action
upon the cord itself or to a paralysis of the sensory nerves,
it is difficult to determine. Ordinarily, in animals rendered
insensible by anaesthetics, the reflex act of respiration con-
tinues ; but this may also be arrested, as has been observed
by all who have experimented with anaesthetics, especially
wTith chloroform. A common way of determining that an
animal is completely under the influence of ether is by an
absence of the reflex act of closing the eyelids when the
cornea is touched.
It now only remains to show that the phenomena of re-
flex action observed in experiments upon the inferior ani-
1 VULPIAN, Systeme nerveux, Paris, 1866, pp. 441, 442.
2 LONGET, Traite de physiologie, Paris, 1869, tome iii., p. 256.
REFLEX ACTION OF THE SPINAL COED. 311
mals, especially frogs, are applicable to the human subject,
and to indicate the muscular actions which depend upon the
cord as a nerve-centre.
It is only necessary, after what has gone before, to indi-
cate in a general way the phenomena observed in the human
subject which illustrate the reflex action of the cord. It is a
common observation, in cases of paraplegia in which the
lower portion of the cord is intact, that movements of the
limbs follow titillation of the soles of the feet, these move-
ments taking place independently of the consciousness or the
will of the subject experimented upon. Acephalous foetuses
will present reflex movements, movements of respiration,
and will even suck when the finger is introduced into the
mouth. Observations of this kind are so numerous and fa-
miliar, that they need not be cited in detail. Experiments
have also been made upon criminals after decapitation ; and
although the reflex phenomena are not so well marked and
cannot be excited so long after death as in cold-blooded ani-
mals, they are sufficiently distinct. In 1869, quite an elab-
orate series of investigations of this kind was made by Ro-
bin.1
It is difficult, in studying, in the human subject, the ordi-
nary phenomena of movements in the voluntary muscular
system, to isolate the reflex phenomena from those acts in-
volving sensation and volition. In many persons, titillation
of the soles of the feet produces violent contractions of
muscles, which cannot be arrested by an effort of the will,
and this may even be followed by general convulsions.
When we unexpectedly touch an irritating surface with the
hand, the muscles of the arm act so quickly, that we may
suppose that this takes place before we really appreciate the
painful sensation ; and, if the impression be very severe, we
may have movements more or less general. Operating upon
highly-sensitive parts, it is frequently impossible to arrest re-
1 ROBIN, Observations anatomiques et physiologiques faites sur des suppli-
cies par decollation, — Journal de Vanatomie^ Paris, 1869, tome vi., p. 69, et seq.
312 NERVOUS SYSTEM.
flex movements, as the closing of the eyelids when the cor
nea is touched. True reflex movements may be produced
by carefully-executed experiments upon persons asleep.
We cannot arrest the act of vomiting induced by titillation
of the fauces ; and other instances of this kind might be
cited.
Most of the true involuntary movements are reflex ; but
these have been or will be considered under their proper
heads. The movements of deglutition depend upon an im-
pression made upon the mucous membrane of the pharynx,
etc. The movements of respiration are excited by an impres-
sion made upon the general sensory nerves, due to want of
oxygen, as we have shown in treating of respiration. The
ejaculation of semen is also reflex. Important reflex actions
take place through the sympathetic nerves, such as the
movements of the intestines, vaso-motor movements, etc. ;
but these will be considered fully under the head of the
sympathetic system. Secretion, the action of the heart,
the contractions of the uterus, the action of the sphincters,
the movements of the iris, etc., take place through the sym-
pathetic and the cerebro-spinal system.
As regards the farther action of the cord as a nerve-centre,
there are undoubtedly many functions influenced more or
less by this portion of the cerebro-spinal axis ; but these have
been treated of under their appropriate heads, or will be con-
sidered hereafter.
CHAPTER XII.
THE CEREBRAL HEMISPHERES.
Pbysiological divisions of the encephalon — Weight of different parts of the
brain and of the entire encephalon — Some points in the physiological anat-
omy of the encephalon and its connections — The cerebrum — General prop-
erties of the cerebrum — Functions of the cerebrum — Extirpation of the
cerebrum in animals — Pathological facts bearing upon the functions of
the cerebrum — Comparative development of the cerebrum in the lower
animals — Development of the cerebrum in different races of men and in
different individuals — Ethnological table, derived from autopsies of white
and negro brains — Table of weights of the encephalon in different indi-
viduals— Location of the faculty of articulate language in a restricted por-
tion of the anterior cerebral lobes.
THE anatomy of the encephalon is so complex, that it can
be treated of with advantage only by a very minute and care-
fully-illustrated description, such as is to be found in some
of the elaborate anatomical works or in special treatises on
the nervous system. We shall not consider under a distinct
head the general physiological anatomy of the brain, for the
reason just given, and also because we are as yet ignorant
of the exact connection between the structure and arrange-
ment of many of its parts and their physiology. "We know
that the gray substance is capable of appreciating general
and special impressions received by the peripheral nervous
system, and of generating the so-called nerve-force. Impres-
sions are conveyed to this portion of the cerebro-spinal axis
by the sensory conductors, passing to the brain, either through
the cord or by the cranial nerves, and by the nerves of special
sense, as well as those of general sensibility. The stimulus
314 NERVOUS SYSTEM.
wliicli gives rise to voluntary movements is generated in the
brain, and is conveyed by the motor nerves to the appro-
priate muscles. We have seen, also, that the centres of the
encephalon may be concerned in reflex action. In addition,
parts of the brain act as centres of sensation and volition and
are concerned in the varied phenomena of intellection.
The encephalon, or what is ordinarily known as the brain,
consists of a number of ganglia, or collections of gray matter,
connected with each other, and also, by the different columns
of the cord, with the motor and sensory nerves of the gen-
eral system. Certain of these ganglia have separate and dis-
tinct functions, which are more or less completely understood ;
while there are, in addition, masses of gray substance, the
physiological relations of which are as yet obscure or entirely
unknown. The greatest and the most important of all, the
gray matter of the cerebral hemispheres, undoubtedly has
subdivisions connected with distinct attributes of the mind ;
but our positive knowledge with regard to these divisions is,
at the present day, very meagre, though this subject has long
been a favorite field for philosophic speculation.
Confining ourselves strictly to the limits of positive infor-
mation, we may recognize the following parts of the encepha-
lon as distinct ganglia : 1. The gray matter of the cerebral
hemispheres ; 2. The gray matter of the cerebellum ; 3. The
olfactory ganglia ; 4. The gray matter of the corpora striata ;
5. The gray matter of the optic thalami ; 6. The tubercula
quadrigemina ; 7. The gray matter of the tuber annulare, or
pons Yarolii ; 8. The ganglion of the medulla oblongata. In
addition, the following parts have been made the subject of
physiological investigation or speculation, with results more or
less definite. The peduncles of the cerebrum and of the cere-
bellum ; the pineal gland ; the corpus callosum ; the septum
lucidum ; the cerebral ventricles ; and the pituitary body.
"We have, however, little if any positive information concern-
ing these parts, except their general anatomical relations ;
and their physiology really amounts to little more than a
THE CEREBRAL HEMISPHERES. 315
history of the vague speculations of the ancients or the fruit-
less experiments of modern observers. It is to be hoped that
future anatomical investigations, chiefly in following out
the course of the fibres of the encephalon and their connec-
tions with the cells of the different collections of gray mat-
ter, will throw light upon the functions of this part of the
cerebro-spinal axis; but at present, all physiologists will
admit that we have received very little aid from this
source. In our anatomical descriptions, therefore, we shall
confine ourselves to those points that are strictly physio-
logical.
Weight of different Parts of the Brain and of the entire
Encephalon. — Most of the tables of the weight of the healthy
adult brain of the Caucasian, given by different observers,
show essentially the same results, the differences amounting
to only one or two ounces for the entire encephalon. The
average given by Quain is 49J ounces, avoirdupois, for the
male, and 44 ounces for the female. This is the general re-
sult obtained by combining the tables published by Sims,
Clendinning, Tiedemann, and Reid. The number of male
brains weighed was 278, and of female brains, 191. In
males, the minimum weight was 34: ounces, and the maxi-
mum, 65 ounces. In 170 cases but of the 278, the weight
ranged from 46 to 53 ounces, which may be taken as the
general average. In females, the minimum was 31 ounces,
and the maximum, 56 ounces. In 125 cases out of the 191,
the weight ranged from 4:1 to 47 ounces.
Quain assumes, from various researches,, that in new-
born infants, the brain weighs 11 '65 ounces, for the male,
and 10 ounces, for the female. In both sexes, " the weight
of the brain generally increases rapidly up to the seventh
year, then more slowly to between sixteen and twenty, and
again more slowly to between thirty-one and forty, at which
time it reaches its maximum point. Beyond that period,
there appears a slow, but progressive diminution in weight
316 NERVOUS SYSTEM.
of about one ounce during each subsequent decennial period ;
thus confirming the opinion, that the brain diminishes in ad-
vanced life."
The comparative weights of the several parts of the en-
cephalon, calculated from observations on the brains of fifty-
three males and thirty-four females, between the ages of
twenty-five and fifty-five, are as follows :
Males.
Females.
Average weight of cerebrum
43'98 oz.
38'75 oz.
5-25 "
4'76 "
Average weight of pons and medulla oblon^ata
0-98 "
roi "
Average weight of entire encephalon
50-21 oz
44-52 oz.
The proportionate weight of the cerebellum to that of
the cerebrum, in the male, is as 1 to 8f, and in the female,
as 1 to 8J.
The specific gravity of the whole encephalon is about
1,036, that of the gray matter being 1,034, and of the white,
1,040.'
The above weights are quoted from Quain's admirable
work on anatomy, and the normal range of variations and
averages only are given. "When we come to treat of the
cerebrum and its relations to intelligence, we will discuss
the weights of the brain in idiots and in persons of extraor-
dinary intellectual power, as far as any data upon these
points are to be found.
Some Points in the Physiological Anatomy of the
cephalon and its Connections. — The direction of the fibres
in the encephalon, their connections with the cells of the
gray substance, the course of commissural fibres connecting
together the different parts of the gray substance of the cere-
brum, the cerebellum, and the deeper ganglia, and finally
the avenues of communication between the fibres of the en-
cephalon and the cord, are points of exceeding intricacy ;
1 QUAIN, Elements of Anatomy, London, 1867, vol. ii., p. 568, et seq.
THE CEREBRAL HEMISPHERES. 317
and many of them are still so uncertain and obscure, that
they cannot as yet be connected satisfactorily with the exact
results of physiological inquiry. All that we can do at pres-
ent, is to recognize certain ganglionic masses, the separate
functions of which have been more or less accurately de-
nned, and show, as far as possible, their anatomical relations
to each other and to the cord.
The separate collections of gray matter concerning which
we possess positive physiological knowledge are, the gray
matter of the cerebral hemispheres and of the cerebellum,
the corpora striata, optic thalami, tuber annulare, or pons,
and the medulla oblongata. To these may be added, the
olfactory ganglia, which preside over the sense of smell, and
the tubercula quadrigemina, or optic lobes, which are the
centres connected with vision. The minute anatomy of the
nerve-fibres and the nerve-cells, with their mode of connec-
tion with each other, have been already considered with suf-
ficient minuteness under the head of the general structure
of the nervous system.1 We shall here discuss chiefly the
direction of the fibres through which the encephalic ganglia
are connected with the periphery, the fibres connecting the
different ganglia with each other, and, in the case of the
larger ganglia, certain commissural fibres connecting to-
gether their different parts.
In the wealth of literature pertaining to the minute
anatomy of the encephalon, it is somewhat difficult to sepa-
rate and define the well-established facts which have a direct
bearing upon physiology. Perhaps the most elaborate and,
to a certain extent, the most satisfactory observations upon
the various points to be considered, are those of Luys ; but
this author describes the course of the fibres with an exacti-
tude that seems hardly justified, in all instances, by the facts,
in view of the inevitable difficulty and uncertainty of some
of the processes employed ; and the graphic and admirable
delineations by which the work is illustrated, though profess-
1 See Chapter I.
318 NERVOUS SYSTEM.
edly schematic, present a degree of ideality which inspires
some distrust with regard to the accuracy of the general
conclusions.1 According to Luys, the fibres of the encepha-
lon have several directions, as follows :
The gray matter of the cerebral hemispheres, as we shall
see farther on, is composed of a mass of nerve-cells, con-
nected together by their prolongations into a plexus, which,
in its turn, is connected with the fibres of the white sub-
stance.
From this cortical cellular plexus, white fibres arise,
which may be divided, according to their direction and des-
tination, into two classes : The first class consists of curved
commissural fibres, which pass into the white substance to a
certain depth and return to the gray matter, connecting thus
the gray substance of adjacent convolutions. The existence
of these fibres and their direction are well established. The
second class consists of fibres which, arising from the gray
substance of the convolutions, connect these with the cor-
pora striata and the optic thalami. These may bo called the
converging fibres ; and their general direction, as far as it
has been ascertained, is as follows :
Arising from the internal, concave surface of the corti-
cal substance of the cerebrum, the converging fibres, at first
running side by side with the curved commissural fibres,
separate from the latter as they curve backward to pass
again to the cortical substance, and are directed toward the
corpora striata and the optic thalami. The limits of the
irregular planes of separation of the commissural and the
converging fibres contribute to form the boundaries of the
ventricular cavities of the brain. If we study the course of
the converging fibres arising from all points in the concave
surface of the cerebral gray matter, we find that they take
various directions. The fibres from the anterior region of
the cerebrum pass backward, and form distinct fasciculi
1 LUYS, Recherches sur le systeme ntrvrux cerebro-spinal, sa sti-ucfure, ses /one-
tions tt ses maladies, Paris, 1865.
THE CEREBRAL HEMISPHERES. 319
which converge to the gray substance of the corpora otriata.
The fibres from the middle portion converge regularly to the
middle region of the external portions of the optic thalami.
The fibres from the posterior portion pass from behind for-
ward, and distribute themselves in the posterior portion of
the optic thalami. The fibres from the convolutions of the
hippocampi and the fascia dentata are lost in the gray sub-
stance lining the internal borders of the optic thalami. In
addition to these converging fibres and the curved commis-
sural fibres connecting the different convolutions of each
hemisphere with each other, are commissural fibres which
connect the two hemispheres, as well as fibres connecting
together the corpora striata and the optic thalami of the
two sides.
Certain of the fibres converging from the gray substance
of the hemispheres to the corpora striata and optic thalami
are probably connected with the cells in the gray matter of
these parts. Other fibres pass through the corpora striata
and optic thalami to become finally connected with the
fibres of the medulla oblongata, and, through the medulla
pblongata, with the columns of the spinal cord. Following
the antero-lateral columns of the cord from below upward,
they ascend to the medulla oblongata, decussate in the me-
dian line, and from the medulla pass to the brain. Certain
of these ascending fibres, which are nearly all continuations
of the antero-lateral columns of the cord, ascend to the brain
by passing deeply through the pons Yarolii ; other fibres as-
cend in the cerebral peduncles, or crura cerebri ; and other
fibres pass to the tubercula quadrigemina. As the bundles
of fibres ascend from the medulla oblongata, they become
more and more numerous by reinforcements of fibres, proba-
bly derived from the cells of the collections of gray matter in
their course.
"We have attempted, in the above sketch of the fibres of
the brain, to give a succinct account of the points that are
most interesting from their physiological relations, and to'
121
320 NEKVOUS SYSTEM.
confine our description, as far as possible, to anatomical facts
that have been definitively settled and are now generally ac-
cepted. But, as we have before remarked, the course of the
fibres and their connections are so exceedingly intricate, that
we cannot rely entirely upon purely anatomical investiga-
tions. The results obtained by anatomists should be con-
trolled, as far as possible, by physiological and pathological
observations. When anatomical researches are directly op-
posed to the conclusions to be deduced from experiments
upon living animals, in view of the great uncertainty of the
former, it will generally be reasonable to assume that they
are erroneous or incomplete. We know, as the results of
experiments on animals, that the motor stimulus is con-
ducted from the brain by the antero-lateral columns of the
cord, and that the conducting fibres decussate at the medulla
oblongata. This fact has been verified by pathological ob-
servations, chiefly in cases of injury to the brain-substance
from haemorrhage, softening, etc. We know that impres-
sions are appreciated as sensations in some part of the cere-
brum, and that the sensory conductors also decussate ; as is
shown by occasional paralysis of both motion and sensation
following brain-lesions. It is evident, therefore, that sensory
conductors pass to the brain, but their precise course is not
easy to determine. We have seen, in treating of the action
of the cord as a conductor, that sensory impressions are
transmitted by the gray substance alone, and it is probably
through connections between the cells of the different cen-
tres that these impressions are finally carried to the brain.
The physiological fact of the conduction of sensory impres-
sions is fully confirmed by pathology, but its mechanism has
been very little, if at all, elucidated by anatomical re-
searches.
We have left certain anatomical points relating to the
cerebrum, cerebellum, tiiber annulare, and medulla oblon-
gata, to be described separately in connection with these
'divisions of the encephalon.
THE CEREBRUM. 321
The Cerebrum.
The anatomical description which we have just given of
the encephalon will answer for most of the points of physio-
logical interest connected with the cerebrum. As we have
seen, the cerebrum constitutes more than four-fifths of the
encephalic mass. Its gray matter, which is external and
follows the convolutions, is from -^ to -J- of an inch in thick-
ness.1 Writers have described this substance as existing in
several layers, but this division is mainly artificial. In cer-
tain parts, however, particularly in the posterior portion of
the cerebrum, the gray substance is quite distinctly divided
into two layers, by a very delicate intermediate layer of a
whitish color.
There is a marked difference in the appearance of the
cells in the most superficial and in the deepest portions of
the gray substance. The superficial cells are small, and
present a net-work of delicate, anastomosing fibres, re-
sembling the cells of the posterior cornua of the gray
substance of the cord ; while the deepest cells are large, and
resemble the so-called motor cells of the cord. Between
these two extremes, in the intermediate layers, there is a
gradual transition in the size of the cells.' This anatomical
fact points to the possibility of distinct functions of the cells
belonging to the superficial and the deep layers ; viz., that
the larger cells are for the generation of the motor stimulus,
while the smaller are for the reception of sensory impres-
sions. This, however, is mere supposition, incapable, as
yet, of positive demonstration.
1 LUYS, Systeme nerveux, Paris, 1865, p. 161.
2 The above general description of the peculiarities of the nerve-cells of the
cerebral convolutions is the one given by most anatomists. Lately, Lockhart
Clark has described the structure of the convolutions very minutely, dividing
the gray substance into seven distinct layers. This description is interesting,
but chiefly so from an anatomical point of view. (LOCKHART CLARK, The
Structure of the Cerebral Convolutions. — Quarterly Journal of Psychological
Medicine, Xew York, 1869, vol. in., p. 517.)
322 NERVOUS SYSTEM.
The mode of connection between the cellular and the
fibrous elements of the nervous system has .already been
considered, and does not demand further mention.1 We
will also pass over the amorphous matter, nuclei, myelo-
cytes, etc., found in the central nervous matter, as these
points possess little or no physiological interest.
General Properties of the Cerebrum. — By the general
properties of the cerebrum, we mean the effect, or the ab-
sence of effect, observed when the gray or white substance
is subjected to direct irritation. While some of the older
writers state that the brain is both irritable and sensible,2
nearly all authorities, up to a very recent date, are agreed
that direct stimulation of the white or the gray substance of
the greatest part of the brain produces neither pain nor
convulsive movements. Among the numerous experimenters
who have exposed the brain and noted the absence of pain
and convulsions after direct stimulation of both the gray
and the white matter, may be mentioned Flourens,3 Ma-
gendie,4 and Longet. Longet states that he has exposed the
cerebrum in goats, and irritated both the white and the gray
substance by laceration, cauterization with potash and nitric
acid, the galvanic current, etc., with purely negative results.6
In numerous experiments upon pigeons, we have invariably
observed the same insensibility and inexcitability of both
the gray and the white substance of the cerebral hemi-
spheres.
1 See page 60.
2 The most definite experiments on this point are those made by Haller and
Zinn, these observers noting, as it seemed to them, indications of pain, and
convulsive movements, immediately following mechanical irritation of the brain.
(HALLER, Memoir -es sur la nature sensible et irritable des parties du corps animal^
Lausanne, 1756, p. 201, et seq.)
8 FLOURENS, Systeme nerveux, Paris, 1842, p. 18.
4 MAGENDIE, Lemons sur les fonctions et les maladies du systeme nerveux, Paris,
1841, tome i., p. 175, et seq.
6 LONGET, Anatomic et physiologic du systeme nerveux, Paris, 1842, tome i.,
pp. 642, 644.
GENERAL PROPERTIES OF THE CEREBRUM. 323
From the above facts, all physiologists of the present day
are agreed that a great part of the substance of the cerebrum
is neither excitable nor sensible, in the sense in which these
terms are applied to the ordinary mixed nerves. There can
be no doubt with regard to the conducting properties of the
white matter of the brain, but the nerve-fibres here seem to
conduct impressions conveyed to them by the sensory nerves
and the stimulus generated by the nerve-cells, without being
capable of receiving or conducting artificial impressions ap-
plied directly to their substance.
We have said that a great part of the cerebral substance
seems to be neither excitable nor sensible to direct stimula-
tion ; but we must make an exception in favor of certain
portions of the cerebrum, which have lately been shown to
possess excitability, their action being confined to particular
sets of muscles. Fritsch and Hitzig, exposing the cere-
bral hemispheres in dogs, found that certain parts of its an-
terior portion responded to a feeble galvanic current. The
stimulation was applied by means of two needles, conducting
a feeble galvanic current, introduced through the gray into the
white substance. Each galvanization produced movements
restricted to particular sets of muscles ; but it was difficult to
say whether the contractions were due to stimulation of the
white or of the gray substance. Different centres for the
sets of muscles were accurately determined. The centre for"
the muscles of the neck was located in the middle of the
frontal convolution ; external to that,* was a centre for the
extensor and adductor muscles of the forelegs ; and so on,
other centres for sets of muscles being found in the anterior
portion of the hemispheres. By passing an interrupted cur-
rent through these parts, tetanus of particular muscles was
produced. In. other observations, when the gray substance
was removed at the points mentioned, there was partial loss
of power, but not paralysis, of the sets of muscles correspond-
ing to the centres operated upon. The authors regarded
this as due to a loss of " muscular sense." In these experi-
324 NERVOUS SYSTEM.
ments, the action was always crossed. It was also found that,
after severe haemorrhage, the excitability of the cerebrum
quickly disappeared, which may account for the negative re-
sults obtained by previous experimenters. ~No motor prop-
erties were found in the posterior portion of the cerebrum.1
The experiments just cited throw a new light upon the
properties of the cerebral substance. It has always been found
difficult to experiment upon the great encephalic centres
without disturbing the physiological conditions so seriously
as to render the results of direct observations of this kind
more or less indefinite. Now that it is ascertained that, in
all probability, these centres readily lose their normal prop-
erties as a simple consequence of haemorrhage and exposure
of the parts, we are less disposed to accept the older experi-
ments, in which the cerebral tissue was apparently shown to
be incapable of receiving direct artificial impressions. There
can be scarcely any doubt with regard to the positive results
obtained by Fritsch and Hitzig ; and it is by no means im-
probable that further investigations may show that other
parts of this centre are excitable. For the present, we can
only accept the definite conclusions drawn by these physiolo-
gists from their direct experiments, admitting that we are
prepared to learn, from further observations, that other parts
have analogous properties.
Functions of the Cerebrum.
The history of the functions of the encephalon belongs
without question to physiology, and is one of the most exten-
1 FRITSCH TJND HITZIG, Utber die electrische ErreglarJceit des Crrosshirns. —
Archiv fur Anatomic, Physiologic, und wissemchaftliche Mcdicin, Leipzig, 1870,
S.' 300, el seq.
In the London Lancet, October 21, 1871, No. xvii., p. 581, is a note stating
tkat the experiments of Fritsch and Hitzig have been confirmed by Schiff. Schiff
is of the opinion, however, that the movements produced by stimulation of the
brain-substance do not depend upon direct excitability of the brain, but are re-
flex, the result of irritation of parts concerned in tactile sensibility. As far as
we know, the experiments of Schiff have not yet been published in full.
FUNCTIONS OF THE CEREBRUM. 325
sive and interesting of the subdivisions of the science ; but
its range is so extensive, that it has long been regarded as a
science by itself, and is only treated of exhaustively in special
treatises on psychology. The study of psychology has been
pursued by the method of observation much more than by
direct experiment. It comprehends, it is true, the facts de-
duced from experiments upon living animals, but the results
obtained by this method are comparatively few 'and their
scope is restricted. Nevertheless, they are sufficiently defi-
nite ; and if these results be corrected and applied to the hu-
man subject by a comparison with pathological facts, there
still remains in psychology much that may be regarded as
within the range of experimental physiology ; for pathologi-
cal cases are very frequently available to the physiologist as
accidental experiments indicating the functions of parts of
the human organism. We cannot restrict ourselves, how-
ever, to this method in the study of the intellectual phenom-
ena ; and must draw upon facts in comparative anatomy and
physiology, anthropology, and, finally, upon the direct obser-
vation and classification of the intellectual processes.
The experimental physiologist has shown that the en-
cephalon may receive impressions and appreciate them as
sensations ; that impressions maybe here connected and give
rise to various of the phenomena of animal and intellectual
existence ; that impressions are recorded by the memory ;
and, finally, that certain parts are endowed with special func-
tions. But beyond this, psychology is a science mainly of in-
trospective observation ; the facts contributed by the experi-
mentalist being few and barren. The observer of intellectual
phenomena studies the process of development of the mind.
He soon separates the instinctive phenomena, observed
in the lower animals, and in the human being without expe-
rience, from the acts which follow experience, observation,
the recording of impressions by memory, and the generation
of ideas. He brings his perfected intelligence to bear upon
the process of development of the same kind of intelligence
326 NERVOUS SYSTEM.
in the human being progressing from infancy to adult life ;
and finally, the psychological philosopher attempts, by intro-
spective observation, to study the workings of the perfect
intellect, his only means of investigation being the very in-
telligence he is endeavoring to comprehend.
If it were possible to bring to bear upon speculative phi-
losophy the same positive methods employed with success in
most of the natural sciences, the results of the study of the
mind would be much more definite ; for we would then be
able to eliminate much that is purely hypothetical, resting
on no established basis in fact. As we are studying the
mind itself with the mind, and as many psychologists en-
deavor to submit their ideas to the test of personal expe-
rience, it is necessary that the investigator should be entirely
free from the disturbing elements of intellectual inaccuracy
or unjustifiable prejudice ; but, unfortunately, the effects of
early impressions made by faulty education are not often en-
tirely removable ; and notions that apparently can never be
supported by facts are apt to take the place of sound philo-
sophic reasoning. Ideas of this kind might, perhaps, be ra-
tionally entertained and discussed at a period when our posi-
tive physiological knowledge amounted to almost nothing,
as before the discovery of the circulation, when our literature
was filled with disquisitions upon the generation of the "spi-
ritus" the location of the passions, etc. ; but as knowledge
has advanced and as established facts are more and more nu-
merous and available in the study of mental phenomena, the
range of pure speculation should become more and more re-
stricted.1
At the present day, we are in possession of a sufficient num-
ber of positive facts to render it certain that there is and can
1 A striking example of rapid advance from the most vague and absurd
mysticism toward positive physiological knowledge is afforded by a comparison
of the "(Eeonomia Regni Animalis" written by Swedenborg, one of the most
learned men of his day, in the middle of the eighteenth century, with the great
work by Haller (Elemenla Physiologice), published only a few years later.
FUNCTIONS OF THE CEREBRUM. 327
be no intelligence without brain-substance ; that when brain-
substance exists in a normal condition, intellectual phenom-
ena are manifested, with a vigor proportionate to the amount
of matter existing ; that destruction of brain-substance pro-
duces loss of intellectual power ; and finally, that exercise of
the intellectual faculties involves a physiological destruction
of nervous substance, necessitating regeneration by nutrition,
here, as in other tissues in the living organism. The brain
is not, strictly speaking, the organ of the mind, for this state-
ment would imply that the mind exists as a force, indepen-
dently of the brain ; but the mind is produced by the brain-
substance ; and intellectual force, if we may term the intellect
a force, can be produced only by the transmutation of a cer-
tain amount of matter.
In view of these facts, which have long been more or less
fully recognized, though not, perhaps, very accurately defined
in words until within a few years, it is not surprising that at-
tempts have been made to locate the different mental attri-
butes in particular portions of the brain.1 The old pseudo-
science of phrenology is the most marked example of such
an attempt ; but this has so slight a basis in fact, that it does
not, at the present day, merit serious scientific discussion.
In treating of the functions of the cerebrum, we shall
not discuss psychology, except in so far as physiologists have
been able to connect the mind, taken as a whole, with a dis-
tinct division of the nervous system. In this we will draw
upon experiments on living animals, facts in comparative
1 Gall, whose labors have hardly received proper consideration at the hands
of many physiological writers, from the fact that he is regarded as the founder
of the untenable system of phrenology, is entitled to the credit of having im
mensely advanced our knowledge of the anatomy of the brain ; but unfortunately,
his visionary and unsupported theories overshadowed his merits as an exact
anatomical investigator. As we do not enter into the early history of anatom-
ical researches, we have not referred before to his great work in six volumes,
which contains a large number of important facts, novel and interesting at the
time of its publication. (GALL, Sur les fonctiom du cerveau et sur celles de cha-
cane de ses parties, Paris, 1822-'25.)
328 NERVOUS SYSTEM.
physiology, in pathology, and, to a certain extent, the rela-
tions clearly shown to exist between the development of in-
telligence and certain of the nerve-centres, in different races
of men and different individuals. With regard to the location
of particular functions in distinct portions of the cerebrum,
we have but little definite knowledge, beyond the experi-
ments already cited in treating of the irritability of the cere-
bral substance, and the probable location of the faculty of
speech. The latter point will be fully discussed in its appro-
priate place.
Extirpation of the Cerebrum in Animals. — It is, perhaps,
sufficiently evident, from anthropological and pathological
observations, as well as the study of comparative physiology,
that the intellectual faculties reside in the encephalon ; but
these methods of investigation do not clearly indicate the
special functions of different parts of the cranial contents.
We have seen, in our general sketch of the anatomy of the
brain, that this is by no means a simple organ, and that cer-
tain parts, though they are bound together by commissural
fibres, have sufficient anatomical distinctness to lead the
physiologist to suppose that they have separate and peculiar
properties and functions. One of the most valuable methods
of investigation of the functions of these separate ganglia is
that of extirpation of one or more, leaving the others, as far
as possible, intact. This method was first employed with
marked success by Flourens, and has since been adopted by
numerous experimenters. It must be remembered, however,
that there is no subject of physiological inquiry in which it
is so difficult to apply experiments on the inferior animals to
the human subject, and none in which the results of experi-
ments should be received with greater caution. The reason
for this is apparent enough. The brain and the intellectual
power of man are so far superior to the development of this
organ . and its properties in the lower animals, that some
philosophers have regarded the human intelligence as distinct
EXTIRPATION OF THE CEREBRUM. 329
in nature as well as in amount. Although we are by no
means prepared to accept this proposition, regarding, as we
must, the intelligence of man as simply superior in develop-
ment to that of the lower animals, it is evident that this
difference in the degree of development is so enormous as to
render the human mind hardly comparable with the intellect-
ual attributes of animals low in the scale. But when the
human brain is slightly developed, as in idiots, or when
the intellectual faculties are simply diminished in activity,
as in certain cases of disease, the being is reduced to a condi-
tion very like that of some of the lower animals.
Experiments upon different classes of animals show clear-
ly that the brain is less important, as regards the ordinary
manifestations of animal life, in proportion as its relative de-
velopment is smaller. For example : if we remove the cere-
bral hemispheres in fishes or reptiles, the movements which
we call voluntary may be but little affected ; while, if the
same mutilation be performed in birds or some of the mam-
malia, the diminished power of voluntary motion is much
more marked. It would be plainly unphilosophic to assume,
because a fish or a frog will swim in water and execute
movements after removal of the hemispheres, very like
those of the uninjured animal, that the feeble intelligence
possessed by these animals is not destroyed by the opera-
tion. It is not only possible, but probable, that in the very
lowest of the vertebrates, the functions of the nervous cen-
tres are not the same as in higher animals. There is, for
example, a fish (the lancet-fish, Amphioxm lanceolatus\ that
has no brain, all of the functions of animal life being regu-
lated by the gray substance of the spinal cord.1 It is essen-
tial, in endeavoring to apply the results of experiments upon
the brain in the lower animals to human physiology, to iso-
late, as far as possible, the distinct manifestations of intelli-
1 MEYXERT, in STRICKER, Handbuch der Lehre von den Geweben, Leipzig, 1868,
S. 695 ; and, VAN DEB HOEYEN, Handbook of Zoology, Cambridge, 1858, voL il,
p. 56.
330 NEKVOTJS SYSTEM.
gence, from automatic movements. Bearing in mind, then,
the difficulties of the question and the caution with which
all observations upon the great nerve-centres of the lower
animals must be received in their applications to pure human
physiology, we will proceed to discuss the phenomena follow-
ing removal or injury of the cerebrum in direct experiments.
In 1822 and 1823, Flourens communicated to the French
Academy of Sciences his remarkable observations upon the
different parts composing the encephalon. His experiments
are so familiar to physiologists, that it is only necessary here
to give his general conclusions. As regards the cerebral
hemispheres, he found that the complete removal of these
parts in living animals, frogs, pigeons, fowls, mice, moles,
cats, and dogs, was invariably followed by stupor, apparent
loss of intelligence, and absence even of the ordinary instinc-
tive acts. Animals thus mutilated retained general sensibil-
ity and the power of voluntary movements, but were thought
to be deprived of the special senses of sight, hearing, smell,
and taste. As regards general sensibility and voluntary
movements, Flourens was of the opinion that animals de-
prived of their cerebral lobes possessed sensation, but had
lost the power of perception, and that they could execute
voluntary movements when an irritation was applied to any
part, but had lost the power of making such movements in
obedience to a spontaneous effort of the will. One of the
most remarkable phenomena observed was entire loss of
memory and the power of connecting ideas. The voluntary
muscular system was enfeebled, but not paralyzed. Eemoval
of one hemisphere produced, in the higher classes of animals
experimented upon, enfeeblenient of the muscles upon the
opposite side, but the intellectual faculties were in part or
entirely retained. Eemoval of even a considerable portion
of both hemispheres was followed by no very marked effect
as regards the intelligence.1
1 FLOURENS, Recherches experimenlales sur Us proprietes et les fonctions da
systenie nerveux, Paris, 1842, pp. .18, 31, 98, etc.
EXTIRPATION OF THE CEREBRUM. 331
The observations of Flourens have been repeated by nu-
merous experimentalists, and were, in the main, confirmed,
except as regards the special senses. Bouillaud, in 1826,
made a large number of observations on pigeons, fowls, rab-
bits, etc., in which, after removal of the hemispheres, he
noted the persistence of the senses of sight and hearing.1
Longet finally demonstrated the fact that both sight and
hearing are retained after extirpation of the hemispheres,
even more clearly than Bouillaud, by the following experi-
ments: He removed the hemispheres from a pigeon, the
animal surviving the operation eighteen days. When this
animal was placed in a dark room and a light was suddenly
brought near the eyes, the iris contracted and the animal
winked ; " but it was remarkable, that when a lighted candle
was moved in a circle, and at a sufficient distance, so that
there should be no sensation of heat, the pigeon executed an
analogous movement with the head." An examination after
death showed that the removal of the cerebrum had been
complete. An animal deprived of the hemispheres also
opened the eyes at the report of a pistol, and gave other
evidence that the sense of hearing was retained.2
AVith regard to the senses of smell and taste, it is more
difficult to determine their presence than to ascertain that
the senses of sight and hearing are retained. It is probable,
however, that the sense of smell is not abolished, if the hemi-
spheres be carefully removed, leaving the olfactory ganglia
intact ; and there is no direct evidence that extirpation of
the cerebrum affects the sense of taste ; indeed, in young
cats and dogs, Longet has noted evidences of a disagreeable
impression following the introduction of a concentrated solu-
tion of colocynth into the mouth, as distinctly as in- the same
animals in a normal condition.3
1 BOUILLAUD, Recherches experimentales sur lesfonction* ducerveau. — Journal
de physiologic, Paris, 1830, tome x., p. 36, et seq.
2 LOSGET, Traite de physiologic, Paris, 1869, tome iii., pp. 328, 329.
8 Op. efc, p. 430.
332 NERVOUS SYSTEM.
We will now proceed to describe, as accurately as possi-
ble, the condition of an animal after complete extirpation of
the cerebrum, as observed in numerous experiments that we
have ourselves made on this subject, premising the statement
that these are merely repetitions of observations made by
other physiologists.
A pigeon, in a perfectly normal condition, is deprived
of the hemispheres, by removing the calvarium and carefully
scooping out the parts with the handle of a scalpel. This
operation is usually not difficult, and the haemorrhage is soon
arrested spontaneously. The slit in the scalp is closed with
sutures, and the animal is set at liberty.
The appearance of the animal after this mutilation is
peculiar and characteristic. There immediately supervenes
a condition of stupor. There is usually no attempt at move-
ment, and, though the pigeon stands upon its feet, the head
is almost buried in the feathers of the neck, the eyes are
closed, and the attitude is one of absolute indifference to
surrounding conditions. The muscles seem to act with just
sufficient vigor to maintain the standing position. If we
pinch one of the toes, or grasp the beak, there is evident
sensation, and a persistent and more or less vigorous effort
is made to release the part. It is sufficiently evident, from
these and other tests, that sensation and the power of volun-
tary motion are retained ; but as soon as the animal is left
quiet, it relapses into its stupid condition, makes no effort
to escape, and apparently loses immediately all recollection
of having been disturbed. The irritation has evidently pro-
duced a sensation of discomfort, and has given rise to a
voluntary muscular effort ; but there has been no idea of
danger, nor an intelligent effort to avoid a repetition of the
disagreeable or painful impression.
It is easy to demonstrate, by experiments such as we
have just alluded to, that the animal sees and hears, and
retains the sense of taste ; but it connects no idea with any
thing seen, and the report of a pistol, which, under natural
EXTIRPATION OF THE CEEEBBUM. 333
conditions, would excite terror and an idea of danger, simply
causes the pigeon to give evidence that the sound has been
heard. As we have already stated, it is probable that the
animal has the sense of smell, but it is difficult, if not im-
possible, to establish this point experimentally. The same
remark applies to the sensations of hunger and thirst. The
animal may feel the want of water and food, but, it has no
idea of relieving these sensations by drinking and eating,
and, if left to itself, will die of inanition.
There has been a great deal of discussion among experi-
mentalists with regard to spontaneous voluntary movements
in animals deprived of the cerebral hemispheres. The ex-
perimental conditions necessary for determining this point
are the following : The observer must be certain that the
removal of the hemispheres has been complete ; for it has
been clearly shown that even when a small amount of cere-
bral substance has escaped, the functions of these lobes are
not entirely abolished. Again, we must be equally certain
that movements which seem to be due to a spontaneous act
of volition take place when the animal has not been aroused
from the condition of stupor which results from the opera-
tion. Generally, when the animal is left to itself, the con-
dition of stupor persists ; but when aroused by artificial
means, it will walk a few steps, plume the feathers, shake
its head, and make various voluntary movements without
further irritation, soon relapsing, however, into somnolency.
One of the most accurate and reliable of the recent observ-
ers of these phenomena, Yulpian, asserts without reserve,
that an animal, deprived completely of the cerebral hemi-
spheres, is incapable of a spontaneous voluntary effort ; and
we are inclined to an unqualified adoption of this opinion.
"With regard to a rabbit, from which Yulpian had removed
the cerebral hemispheres and the corpora striata, he makes
the following statement : " I do not hesitate to say that this
rabbit is completely deprived of spontaneous volition. All
its movements, which are, indeed, much less varied than
334 NERVOUS SYSTEM.
those of a bird operated on in the same manner, are ex-
clusively and directly due to a stimulation produced by
exterior excitations, or by interior inclinations, such as fa-
tigue, etc." l
In view of the very great variety of movements that
occur in animals after removal of the cerebrum, it is quite
difficult to define precisely what movements are due to vol-
untary action depending upon some external or interior im-
pression, which are really reflex voluntary movements, and to
distinguish them from those which arise from a spontaneous
and, perhaps, an intelligent effort of the will. These points
have been so admirably described in a recent article, by
Onimus, that we quote his concluding summary :
" As a summary, in the inferior animals, as- in the supe-
rior animals, the removal of the cerebral hemispheres does
not cause to disappear any of the movements that previous-
ly existed. Only, these movements assume certain peculiar
characters. In the first place, they are more regular, they
have the true normal type, for no psychical influence inter-
venes to modify them ; the locomotor apparatus is brought
into action without interferences, and one could almost say
that the ensemble of movements is then more normal than
in the normal condition.
"In the second place, the movements executed take
place inevitably after certain excitations. It is a necessity
that the frog placed in water should swim, and that the
pigeon thrown into the air should fly. The physiologist
can then, at will, in an animal without the brain, determine
such and such an act, limit it, arrest it ; he can anticipate
the movements and affirm in advance that they will take
place under certain conditions, absolutely as the chemist
knows in advance the reactions that he will obtain in mix-
ing certain bodies.
" Another peculiarity in the movements that take place,
when the cerebral lobes are removed, is their continuation
1 VULPIAN, Systems nerveux, Paris, 1866, p. 680.
EXTIRPATION OF THE CEREBRUM. 335
after a first impression. On the ground, a frog without the
brain when irritated makes, in general, two or three jumps
at the most ; it is rare that it makes but one. Placed in
water, it continues the movement of natation until it meets
with an obstacle ; it is the same in the carp, eel, etc. The
pigeon continues to fly, the duck and goose continue to
swim, etc. We should say that there is a spring which
needs for its action a first impulsion, and which is stopped
by the slightest resistance. But, what is striking, is pre-
cisely that continuation of the condition once determined,
and we cannot refrain from connecting the facts observed in
an animal deprived of the cerebral lobes with those which
constitute the characteristic properties of inorganic matter.
Brought into movement, the animal without a brain retains
the movement until there is exhaustion of the conditions of
movement, or until it meets with resistance ; taken in re-
pose, it remains in the state of inertia until an exterior
cause intervenes to bring it out of this condition. It is
living, inert matter." l
There is now no room for discussion with regard to the
persistence of general sensibility after removal of the hemi-
spheres. The experiment upon a pigeon leaves no doubt
upon this point ; but the susceptibility to pain has been
much more strikingly illustrated in other animals. Yulpian,
in describing the condition of animals operated upon in this
way, illustrates the persistence of sensibility in rats and rab-
bits, by the violent cries which follow painful impressions.2
In concluding our consideration of the observations upon
inferior animals, it only remains for us to discuss briefly cer-
tain late experiments, which have attracted a great deal of
attention, from the fact that they seem to show that sponta-
neous volition exists after complete extirpation of the cere-
brum. These experiments have been most ably and satis-
1 OXIMUS, Reclierches experimentaJ.es sur les phenomenes consecutifs d Tablation
du cerveau. — Journal de t anatomic, Paris, 1870-"7l, tome vii., p. 644.
2 VULPIAN, Systeme nerveux, Paris, 1866, p. 667.
122
336 NERVOUS SYSTEM.
factorily analyzed by Yulpian.1 Goltz argues, from experi-
ments on frogs and the movements executed after extirpation
of 'the brain, that these animals make intelligent muscular
efforts when deprived of the hemispheres ; and the phenom-
ena observed after this mutilation are indeed very curious.
As was shown by Yulpian, in his own experiments, frogs and
fishes thrown into water will swim about and the frogs will
even succeed in getting out of the water, but then they im-
mediately relapse into a torpid condition. We do not con-
ceive that these facts are in opposition to the statement just
made with regard to the absence of spontaneous volition in
birds and the mammalia, particularly in view of the slight
importance of the functions of the cerebrum as compared with
the spinal cord in the lower orders of vertebrate animals.
The views lately advanced by Yoit are based upon an iso-
lated experiment upon a pigeon that was kept alive for five
months after the cerebral lobes had been, as stated by Yoit,
completely removed. At first the pigeon presented the phe-
nomena usually observed after this operation ; but it gradu-
ally recovered, until finally it seemed entirely normal, with
the single exception that it never would eat, all food being
introduced forcibly. Five months after the operation, the
pigeon was killed and the encephalic cavity was found filled
with a white substance containing dark-bordered nerve-fibres
and 'nerve-cells. Yoit never before observed any thing like
regeneration of the nervous substance or so complete a res-
toration of the cerebral functions ; and he regarded this as
an instance of anatomical and physiological regeneration of
the hemispheres. The objections to accepting this observa-
tion with the physiological conclusions presented by Yoit
are, that it is not only possible but probable, that the hemi-
spheres were not entirely removed, and that the posterior
portion of the encephalon had advanced to occupy in part
the space originally filled by the extirpated mass.2 "While
1 Archives de physiologic, Paris, 1869, tome ii., p. 301.
5 GOLTZ, Contributions d Petude des fonctions du cerveau de la grenouille ;
FUNCTIONS OF THE CEREBRUM. 337
we do not assume that anatomical and functional regenera-
tion of the cerebrum in a pigeon is impossible, it must be
admitted that such an extraordinary statement as that made
by Yoit cannot be accepted without reserve, upon the basis
of a single observation.1
Pathological Facts bearing upon the Functions of the
Cerebrum. — A careful study of the phenomena which attend
certain pathological conditions of the brain in the human
subject, such as laceration or pressure from effusion of blood,
softening of the nervous substance, etc., taken in connection
with the results _of experiments upon living animals, throws
considerable light upon the functions of certain distinct por-
tions of the encephalon. Cerebral haemorrhage very common-
ly involves the corpus striatum, either directly or indirectly,
and then we have paralysis of motion limited to the side of
the body opposite to the lesion. When the optic thalamus is
affected, there is impairment of sensibility upon the opposite
half of the body. These facts illustrate the course of the
motor and sensory conductors from and to the cerebrum.
It is not very common to observe lesions confined to the
gray or white substance of the hemispheres, but when this
occurs, and when there is no pressure upon the corpora
striata or optic thalami, there is no paralysis of motion or
sensation, though there may be a certain amount of weak-
ness of the muscles upon the side of the body opposite to
the injury. Experiments upon the inferior animals have
ROSEXTHAL, Sur les mouvements qui ont lieu apres Fablation des hemispheres
cerebraux ; Sur un pigeon auquel le professeur Volt avail enleve les hemispheres
cerebraux dans le mcis de juillet 1861 ; YOIT, Observations sur Fablation des
hemispheres cerebraux chcz le pigeon. — .Archives de physiologic, Paris, 1869, tome
ii., p. 301.
1 YOIT, Phenomenes qui suivent Fablafion des hemispheres du cerveau chez les
pigeons. — Revue des cours scientifiques, Paris, 1868-1869, tome vi., p. 256.
This observation has already been detailed in full, in connection with the
question of the possible regeneration of the nerve-centres after extirpation,
(See page 63.)
338 NEKVOUS SYSTEM.
confirmed the conclusions to be drawn from these pathologi-
cal facts. In frogs, fishes, and birds, when one hemisphere
has been removed, the evidences of feebleness of the muscles
of the opposite side are not very marked ; but they are quite
distinct in the adult mammalia. Yulpian noted, in experi-
ments upon dogs, that the destruction of a portion of one
cerebral hemisphere produced feebleness, but a very incom-
plete paralysis of motion upon the opposite side.1
It is a fact now generally admitted in pathology, that loss
of cerebral substance from repeated haemorrhage is sooner
or later followed by impairment of the intellectual faculties.
This point it is frequently difficult to determine in a single
instance, but an analysis of a sufficient number of cases
shows impaired memory, tardy, inaccurate, and feeble con-
nection of ideas, abnormal irritability of temper, with a child-
ish susceptibility to petty or imaginary annoyances, easily-
excited emotional manifestations, and a variety of phenom-
ena denoting abnormally feeble intellectual power, following
any considerable loss of cerebral substance. In short, patho-
logical conditions of the brain all go to show that the intel-
lectual faculties reside in the cerebral hemispheres.
As a final argument drawn from pathology, in favor of
the view just stated, we have only to allude to the size of
the brain in certain cases of idiocy. Prof. Hammond, in his
admirable work on " Diseases of the Nervous System," has
cited several examinations of the brain in idiots, in which
this organ has been found to be less than one-half of the
ordinary weight ; as the cases reported by Tiedemann, of
19f, 25f , and 22^- ounces, in three idiots, whose ages were,
respectively, sixteen, forty, and fifty years.2 A case was
reported by Mr. Gore, of an idiotic woman, forty-two years
of age, whose brain weighed ten ounces and five grains ; 3
1 VULPIAN, Systcme nerveux, Paris, 1866, p. 677.
2 HAMMOND, Diseases of the Nervous System, New York, 1871, p. 326.
3 GORE, Notice of a case of Micro-ccphaly. — Anthropological Review, London,
1863, No. i., p. 170.
FUNCTIONS, OF THE CEKEBEUM. 339
and one is reported by Mr. Marshall, of an idiotic boy, twelve
years old, whose brain weighed but 8^ ounces.1 Mr. Brad-
ley, in a late number of the Journal of Anatomy and Phys-
iology^ gives an elaborate description of the brain of an
idiot, thirty-five years of age, extremely emaciated at the
time of his death, when he weighed but sixty pounds. The
encephalon, including the cerebrum, cerebellum, and pons,
weighed twenty-eight ounces, and the proportion of the
cerebellum to the cerebrum was as 1 to 5 '5. In the healthy
adult male, of ordinary weight, the encephalon weighs fifty
ounces, and the proportion of the cerebellum to the cerebrum
is as 1 to 8f. Mr. Bradley calls attention to the proportion
of the cerebellum to the cerebrum in this case, stating that
this is common in the encephalon of idiots.2 In idiots, the
weight of the body is generally much below the normal stand-
ard ; and in the case reported by Bradley, the proportionate
weight of the encephalon to that of the entire body is even
greater than in the healthy adult. If, for example, we double
the weight of the body and the brain, we would have, for
one hundred and twenty pounds of weight, an encephalon
of fifty-six ounces. This. point, however, cannot be admitted
as an argument against the fact that congenital idiocy is
usually attended with an abnormally small development of
the hemispheres. Most idiots take little or no exercise ; they
are under-sized, and have but little muscular vigor ; and it is
probable that the general development of the body is more
or less a consequence of the abnormal cerebral condition.
1 MARSHALL, Brain and Calvarium of a Microcephale. — Anthropological He-
view, London, 1863, No. ii., Appendix, containing the Transactions of the An-
thropological Society of London, p. ix.
2 BRADLEY, Description of the Brain of an Idiot. — Journal of Anatomy and
Physiology, Cambridge and London, 1871, vol. vi., p. 67.
Gratiolet, in an article on microcephaly, states that the development of the
cerebellum, in proportion to the size of the cerebrum, is enormous, and that
the reduction in the size of the encephalon is almost exclusively in the cerebral
hemispheres. (Memoire sur la microcephalie. — Journal de la physiologic, Paris,
1860, tome iii., p. 115.)
34:0 NEKVOUS SYSTEM.
We might compare the weight of the body in Mr. Bradley 's
case with that of a child from seven to fourteen years of age ;
and at this period of life, according to the tables compiled
by Quain, the average weight of the encephalon is 45-96
ounces, for the male, and 40*78 ounces, for the female.1
The statements just made with regard to the brains of
idiots refer to cases characterized by complete absence of in-
telligence, and furthermore, probably, by very small develop-
ment of the body. On the other hand, there are instances
of idiocy, the body being of ordinary size, in which the weight
of the encephalon is little if any below, the average. Lehit
reports several cases of this kind. In one of these, a deaf-
mute idiot, forty-three years of age, a little above the ordinary
stature, presenting " idiocy of the lowest degree ; no speech ;
almost no sign of intelligence ; no care for cleanliness," the
encephalon weighed 48'32 oz. Other cases of idiots of
medium stature are given, in which the brain weighed but
little less than the normal average. a These facts illustrate
the difficulty of subordinating individual observations to any'
general rule, and this is particularly marked with regard to
the brain, the structure of which is so complex and difficult
of investigation.
Comparative Development of the Cerebrum in the Lower
Animals. — It is only necessary to refer very briefly to the de-
velopment of the cerebrum in the lower animals as compared
with the human subject, to show the connection of the hemi-
spheres with intelligence. In man, the cerebrum presents an
immense preponderance in weight over other portions of the
encephalon ; and in some of the lower animals, the cerebrum
is even less in weight than the cerebellum. In man, also, not
only the relative but the absolute weight of the brain is greater
than in lower animals, with but two exceptions. Todd cites
1 QUAIN, Elements of Anatomy, London, 1867, vol. ii., p. 569.
2 LELUT, Du poids du ccrveau considere dans ses rapports avec le developpement
de T intelligence. — Physiologic de lapensee, Paris, 1862, tome ii., p. 308.
THE CEREBRUM IX DIFFERENT RACES, ETC. 341
a number of observations made upon the brains of elephants,
in which the weights ranged from nine to ten pounds.1
Rudolphi gives the weight of the encephalon of a whale,
seventy-five feet long, as considerably over five pounds.2
With the exception of these animals, man possesses the
largest brain in the zoological scale.
Another interesting point in this connection is the de-
velopment of cerebral convolutions in certain animals, by
which the relative amount of gray matter is increased. In
fishes, reptiles, and birds, the surface of the hemispheres is
smooth ; but in many mammalia, especially in those remark-
able for intelligence, the cerebrum presents a greater or less
number of convolutions, as it does in the human subject.3
Comparing the relative size of the brain, its complexity
of organization, and the increase of its gray substance by
convolutions, with the development of intelligence in the
animal scale, it is so evident that the cerebrum is the seat of
the intellectual faculties, that this point in our argument
seems to need no farther discussion.
Development of the Cerebrum in Different Races of
and in Different Individuals. — It may be stated as a general
proposition, that in the different races of men, the cerebrum
is developed in proportion to their intellectual power ; and
in different individuals of the same race, the same general
rule obtains. Still, this law presents marked exceptions.
Certain brains in an inferior race may be larger than the
average in the superior race ; and it is frequently observed
that unusual intellectual vigor is coexistent with a small
brain, and the reverse. These exceptions, however, do not
take away from the force of the original proposition. As
1 TODD, Cydopcedia of Anatomy and Physiology, London, 1839-'47, vol. iii.,
p. 664, Article, Nervous Centres.
8 RUDOLPHI, Grundlss der Physiologic, Berlin, 1823, Bd. ii., Erste Abthei-
lung, S. 12.
3 VAX DER HOEVEN, Handbook of Zoology, Cambridge, 1858, vol. ii., pp. 42,
227, 358, 596.
342 NEKVOUS SYSTEM.
regards races, the rule is found invariable, when a sufficient
number of observations are analyzed, and the same holds
true in comparing a large number of individuals of the same
race. Average men have an advantage over average women
of about six ounces of cerebral substance ; and, while many
women are far superior in intellect to many men, such in
stances are not sufficiently numerous to invalidate the general
law, that the greatest amount of intellectual capacity and
mental vigor goes with the greatest quantity of cerebral sub-
stance. If we accept the view, which is in every way rea-
sonable, that the gray substance of the cerebral hemispheres
is the generator of the mind, it would be necessary, in com-
paring different individuals with the view of establishing a
definite relation between brain-substance and intelligence,
to estimate the amount of gray matter ; but it is not easy
to see how this can be done with any degree of accuracy.
It is undoubtedly true that proper training and exercise
develop and increase tho vigor of the intellectual faculties ;
and that thereby the brain is increased in power, as are the
muscles, under analogous conditions. This will perhaps ex-
plain some of the exceptions above indicated ; but an addi-
tional explanation may be found in differences in the quality
of brain-substance in different individuals, independently of
the size of the cerebral hemispheres. One evidence that
these differences in the quality of intellectual working matter
exist is, that some small brains actually accomplish more
and better work than some large brains. This fact mny be
due to differences in training, to the extraordinary develop-
ment in some individuals of certain qualities, to intensity
and pertinacity of purpose, capacity for persistent labor in
certain directions, a fortunate direction of the mental efforts,
opportunity and circumstances, etc. But, aside from these
considerations, there are analogies in the muscular system,
which render it exceedingly probable that there are impor-
tant individual differences in the quality of generating ner-
vous matter.
THE CEREBRUM IX DIFFERENT RACES, ETC. 34:3
TTe have in our mind at this moment two persons, in a
condition of perfect health and muscular development, who
have devoted about fifteen years to the same kind of athletic
exercise, but who present the most marked differences in
muscular power. One of these has an enormously-developed
muscular system, the muscles being large and as hard as is
ever seen. In this individual, the arm over the biceps meas-
ures seventeen inches in circumference. He can raise from
the shoulder with the right hand and stand erect with the
arm straight under a weight of a little less than one hundred
pounds. The other individual has muscles of about the same
hardness, but very much smaller. His arm measures over
the biceps a little more than fourteen inches ; but he can
raise from the shoulder a weight of one hundred and thirty-
eight pounds. A third individual can " put up " from the
shoulder, a dumb-bell of the enormous weight of one hundred
and eighty-one pounds. This feat we have seen executed,
and have accurately verified the weight. The gentleman
referred to, Mr. Richard A. Pennell, of Xew York, is not a
professional gymnast, but is one of the strongest men, in this
particular exercise, on record, certainly in this country. His
height is five feet ten inches ; weight, one hundred and
ninety-five pounds, without clothing ; his muscles are large,
but rather soft. As this exhibition of muscular power is,
we believe, almost unparalleled, we may state that the weight
is pushed slowly and gradually from the shoulder, the arm is
straightened, and the body is brought to an erect position
under the weight, which is held perfectly balanced in the
right hand for several seconds. Less striking examples of
such differences in muscular quality are innumerable, and
must have been observed by those interested in athletic exer-
cise ; and in view of this, it seems not only possible but prob-
able, that the generating portion of the nervous system pos-
sesses analogous differences in quality in different persons.
In concluding this portion of our argument, we present
a table of an exceedingly interesting series of observations
344 JS'ERVOUS SYSTEM.
of the comparative weights of the encephalon in the Cauca-
sian, tue negro, and the intermediate grades produced by the
union of the two races. The observations in this table are
hardly sufficient in number to establish the exact relations
between the brains in the different grades of color, but they
illustrate points of peculiar interest in this country, where
the blacks are so numerous, a-1 1 where the union of the two
races, white and black, is so common. As far as the re-
sults go. they are in decided opposition to those given by
Tiedemann, in his remarkable memoir on the brain of the
negro.1
We also give a list of some of the well-authenticated
weights of the encephalon in men whose intellectual faculties
had been observed during life.2 This latter list we have pre-
pared with great care, and have introduced some observa-
tions not found in the works on physiology. In estimating
the intellectual power of individuals, it is difficult to arrive
at exact conclusions, except with regard to men of acknowl-
edged eminence. Still, the statements are as accurate as
possible, and must be taken for what they are worth. Sev-
eral of the examples given in this list are marked exceptions
to the general rule, that the mental vigor is in proportion to
the development of brain-substance.9
1 TIEDEMANN, Das Him des Negers, Heidelberg, 1837.
2 We have not considered it necessary to enter into a discussion of the rela-
tions of the facial angle to intelligence, in the lower animals and in different
races of men. It was proposed by Camper to take the angle made at the junc-
tion of two lines, one drawn from the most projecting part of the forehead to
the alveolae of the teeth of the upper jaw, and another passing horizontally back-
ward from the lower extremity of the first line, as the facial angle. This angle
is, to a certain extent, a measure of the projection of the anterior lobes of the
brain. Numerous observations upon the facial angle in different races were
made by Camper and other physiologists and ethnologists. They show, in gen-
eral terms, that the angle is larger in man than in any of the inferior animals, and
is largest in those races that possess the greatest development of intellectual
power. (CAMPER, Dissertation physique sur les differences reelles que presentent
les traits du visage, etc., Autrecht, 1791. BROCA, Sur tangle facial ft le triangle
facial. — Mhnoires d'anthropologie, Paris, 1871, tome i., p. 110.)
THE CEREBRUM IN DIFFERENT RACES, ETC.
345
Ethnological Table, derived from 405 Autopsies of White and .Negro
Brains. Made under the direction of Surgeon Ira Russell, llth
Massachusetts Volunteers.1
*
4.
Tn
2
|
0
q
9
i
f)
of Antopsi
1
\t
o
£ =
6
|
&
s
iis, :>:. JUKI
dcr (ill ox,.
ns, 50 and
dcr 55 oz.
1
ns, 40 and
dcr If) o-/..
ns, 85 and
dcr -10 (>/.
!§
1
O
<
a
i
|
1
1
1 '
2
-
-
1
24
White
52-06
64
-44|
1
4
11
7
1
.
.
25
1 '
49-05
51
40
1
_
10
12
2
.
47
£ '
47-07
57
37s-
2
13
19
12
1
51
i <
46-54
59
38£
.
2
10
22
11
6
.
95
46-16
57
34^
1
15
50
21
7
1
22
i^ i
45-18
60*
40
.
.
3
10
9
.
.
141
Black
46-96
56
35 1
•
5
42
51
38
3
•
405
2
14
104
171
94
17
1
Autopsies of
Whites,
Clendinning,
collated
Sims, Reid,
from
and
various
Tiedemann
278
sources
49^
65
34
7
28
99
97
39
7
1
Ta&Ze o/ Weights of the EncepJialon, in ounces, av., in Individuals, in
some of whom the Degree of Intelligence is more or less accurately
known,
1. Cromwell,2 aged 59 (not accepted by physiologists)
2. Byron,3 aged 36 (not accepted by physiologists)
3. Cuvier, aged 63
4. Abercrombie, aged 63
82-29 oz.
79-00 "
64-33 "
63-00 "
1 SAXFORD B. HUNT, The Negro as a Soldier. — Quarterly Journal of Psycho-
logical Medicine, Xew York, 1867, vol. i., p. 182.
2 Weight taken from WAGNER, Fonctions du cerveau. — Journal de la phy-
sioloyie, Paris, 1861, tome iv., p. 556. Soemmerring (De Corporis Humani
Fali'ica, Trajecti ad Moenum, 1798, tomus iv., p. -38) states that he examined
the skull of Cromwell, and thinks, from the size of the cranial cavity, that the
weight of the brain ordinarily given must be inaccurate.
3 Dissection of Lord Byron. — Medico- Chirurgical Review, London, 1825, vol.
.i. (American Reprint), p. 164. The statement is quoted from the Gazette de
sante, 25 August, 1824, that " tiie cerebmm and cerebellum weighed six medi-
cinal pounds" This equals 79 oz. av., less 25 grains. This statement is made
on the authority of Dr. Bruno, and is certainly inaccurate, especially as many
biographers of Byron state that his head was unusually small.
346 NERVOUS SYSTEM.
6. Ruloff, aged 53; above medium stature; executed for murder, in
1871 ; well versed in languages, imagining that he had dis-
covered new and important principles in philology . . . 5 9 '00 oz
6. James Fisk, Jr.,1 aged 37 ; killed in New York, in 1872 ; illiterate,
but said to possess great executive ability ; notorious for co-
lossal and unscrupulous financial speculations . . . 58*00 "
7. Spurzheim 55*06 "
8. Adult man;2 an idiot since two years of age .... 64*95 "
9. Laborer,2 aged 22 ; died of fracture of the pelvis . . . 53*79 "
10. Daniel Webster, aged 70 63-50 "
11. Celebrated mathematician,2 aged 54; above the ordinary stature 53*41 "
12. Executed criminal,3 aged 45 ; medium stature; of less than ordi-
nary intelligence, and uncultivated 53*12 "
13. Celebrated clinical professor,2 aged 62 ; medium stature . . 52*88 "
14. Mathematician of the first rank,2 aged 78 ; medium stature . 52*62 "
15. Executed criminal,3 aged 34 ; rather large in stature ; ordinary in-
telligence, but singular, and somewhat cultivated . . . 50*09 "
16. Dupuytren, aged 58 49*68 "
17. Day-laborer,2 aged 49 48*85 "
18. Executed criminal,3 aged 29 ; medium stature ; of scarcely ordi-
nary intelligence, and uncultivated 48*81 "
19. Executed criminal,4 aged 42 ; a little above medium stature ; in-
telligence fine, developed, and slightly cultivated . . . 48*81 "
20. Idiot, of a very low degree of intelligence ; 4 aged 37 ; a little above
medium stature ; movements very active .... 48*67 "
21. Deaf-mute,4 aged 43 ; a little above medium stature ; an idiot, of
the lowest degree of intelligence 48*32 "
22. Executed criminal,4 aged 46 ; medium stature ; of ordinary intelli-
gence, uncultivated, but proud and vivacious . . . 48*14 "
23. Man, slightly imbecile,4 aged 67 ; medium stature . . . 48*14 "
24. Man about 60 years of age 5 48*14 "
25. Celebrated philologist,5 aged 54 ; 5 feet 7£ inches tall . . 47*90 "
26. Executed criminal,4 aged 34 ; small stature ; intelligence developed
and cultivated 47 '79 "
27. Man, about 24 years of age ; 5 died of aortic insufficiency . . 47*69 •'
28. Day-laborer,5 aged 51 . 47*44 "
29. Man 34 years of age;5 died of pneumonia 47*26 "
1 This is taken from the official report of the autopsy of James Fisk, Jr., by
Dr. E. T. T. Marsh, deputy coroner, on file in the office of the district attorney,
in the city of New York. The cerebrum weighed 51 ounces; the cerebellum,
6 oz., and the pons, 1 oz.
2 WAGNER, Journal de la physiologic, Paris, 1861, tome iv., p. 558.
8 LELUT, Physiologic de la pensec, Paris, 1862, tome ii., pp. 304-310.
4 LELUT, loc. cit. 6 WAGNER, loc. cit.
THE CEREBRUM IX DIFFERENT RACES, ETC. 347
30. Brigand and assassin,1 aged 32 ; beheaded 46*91 oz.
31. Idiot of the lowest degree of intelligence,2 aged 24 ; medium stature 46*56 "
32. Executed criminal,8 aged 27 ; medium stature ; of ordinary and
uncultivated intelligence 46*21 "
33. Executed criminal,2 aged 40 ; at least of medium stature ; intelli-
gence developed and cultivated 46*21 "
34. Railroad laborer,1 aged 23 46*21 "
35. Executed criminal,2 aged 29; intelligence hardly ordinary, and
uncultivated 45-50 "
36. Wood-cutter,1 aged 57 ; died of vertebral caries . . . 44*90 "
37. Idiot, below the condition of a brute ; 2 aged 39 ... 44'30 u
38. Imbecile, with difficulty in movements ; 2 aged 57 ; intelligence
correct, notwithstanding its slight development . . . 43*56 "
39. Man, 34 years of age ; 1 died of phthisis 43*38 "
40. Celebrated mineralogist,1 aged 77 ; above medium stature . . 43*24 "
41. Executed criminal,2 aged 31; small stature; intelligence mobile
and exaggerated 42*04 "
42. Upholsterer,1 aged 60 ; died of phthisis 40*91 "
43. Imbecile,5 aged 23 ; large stature 38*97 "
44. Idiot, of the lowest degree of intelligence ; 2 aged 46 ; medium
stature 36*86 "
45. Man, 46. years of age ; 2 idiocy very profound ; very large stature 36*15 "
46. Man, 44 years of age ; 2 idiocy very profound ; a little below me-
dium stature .... 34*39 "
In compiling the foregoing table, we have in every in-
stance consulted the authentic reports of the weights of the
brain, and have reduced them all to ounces av. with the
greatest care. This was found necessary, on account of the
important variations in the reports quoted by different phys-
iological authors, especially as regards the brains of Cuvier,
Webster, and Dupuytren. "We believe that our figures are
absolutely correct. The weights of the brains of Cromwell
and Byron are given, but there can be hardly any question
that they are grossly exaggerated.
In the report of the autopsy of Cuvier, the weight of the
brain is given as "trois livres onze onces quatres gi*os et
demi" : Cuvier died in 1832, and the weight is in the old
1 WAGXER, loc. cit. 2 LELUT, loc. fit.
3 Note sur la maladie et la mort de G. Cuvier. — Archives generates de mede-
line, Paris, 1832, tome xxix., p. 144.
348 NERVOUS SYSTEM.
poids de marc" l the livre = 7,561 troy grains. The weight
above given, reduced to ounces av., = 64-33.
The weight of the brain of Abercrombie is taken from
the original report furnished by Dr. Adam Hunter.2 The
weight of the brain of Kuloff is taken from a full report of
the autopsy in the Psychological Journal.3 The weight of
the brain of James Fisk, Jr., was furnished by Dr. Edward
T. T. Marsh, Deputy Coroner of New York, who conducted
the autopsy.4 The weight of Spurzheim's brain was taken
from the Medico- Qhirurgical Review?
The report of Daniel "Webster's brain is certainly a curi-
osity in scientific literature. In the account .of the autopsy,
by Dr. Jeffries, of Boston, the actual weight of the enceph-
alon, taken by that most accurate and reliable observer, Dr.
Jeffries "Wyman, was 5 3 '5 oz. av. It is stated, however, by
Dr. Jeffries, that " the weight of the brain deviated much
less from the average than the measurements ; it was en-
tirely out of proportion to the unusual dimensions of the
cranial cavity. . . . Both serum and lymph, there can be no
doubt, encroached upon and occupied the space once filled
with cerebral substance. The weight given above, there-
fore, cannot be regarded as being equal to the weight of , the.
brain in a state of health." To supply this hypothetical de-
ficiency in cerebral substance in this remarkable man, Dr.
Jeffries, aided by Prof. Treadwell, of Cambridge, makes an
1 In 1812, by a ministerial decree, the livre was fixed at 500 grammes, in-
stead of 489'5 grammes, the equivalent of the livre poids de marc ; but the old
weight was generally in use in 1832, and all of the calculations, both for Cuvier
and Dupuytren, are from the poids de marc. As far as we can ascertain, the
livre of 500 grammes was little used, and should not be taken, unless expressly
stated.
2 Account of the late Dr. Abercrombie. — Edinburgh Medical and Surgical
Journal, Edinburgh, 1845, vol Ixiii., p. 448.
3 BURR, Medico-legal Notes on the Case of Edward H. Rulo/. — Journal of Psy-
chological Medicine, New York, 1871, vol. v., p. 738.
4 Written communication from Dr. Marsh.
5 The STcull of Spurzheim. — Medico- Chirurgical Review, London, 1836, New
Series, vol. xxv. (American Reprint), p. 448.
THE CEREBROI IX DIFFEKEXT KACES, ETC. 349
approximative calculation, based upon the cranial capacity,
the specific gravity of the brain (according to Cruveilhier,
and not the actual specific gravity of the brain examined),
and arrives at the conclusion that " Mr. Webster's brain will
be found to rank among those whose brains are generally
cited as instances of remarkable size." The brain of Cuvicr
is then given as weighing 64J oz. ; Webster, 63f pz. ; and
Abercrombie, 63 oz. It is impossible to avoid the suspicion,
in reading this report, that an attempt is made to make the
weight of the brain accord with the acknowledged remark-
able intellectual power of Mr. Webster, as well as the un-
usual cranial capacity.1
The account of Dupuytren's brain, the weight of which
is often misquoted by authors, is taken from the official re-
port of the autopsy, published in the Revue medicate. The
encephalon weighed 2 livres, 14 onces. Taking this z&poids
de marc, the weight is 49'68 oz. av.3
The other weights given in the table are taken from
Lelut 3 and Wagner.4
A careful study of the weights given in the preceding
table shows the impossibility of applying to individuals an
absolute rule that the greatest brain-power is connected with
the greatest amount of brain-substance. The men of acknowl-
edged intellectual ability in the table are, Cuvier, Abercrom-
bie, Spurzheim, Webster, Dupuytren, and those cited by
Wagner as celebrated mathematicians, professors, etc. Cu-
vier and Abercrombie stand at the head of the list, as re-
gards the weight of the brain ; but above Webster and
Dupuytren, are Ruloff, Fisk, an idiot, and a common labor-
er. Far down in the list, is a celebrated mineralogist, whose
brain, is at least six ounces below the average. The ad-
1 JOHN JEFFRIES, An Account of the last Illness of the late Honourable Daniel
Webster, — American Journal of the Medical Sciences, Philadelphia, 1853, Xe\v
Series, vol. xxv., p. 117, et seq.
% CRUVEILHIER, Hcssox, BOUILLAUD, Froces-verbal de Touverture du corps df
M. Dupuytren. — Revue medicale^ Paris, 1835, tome i., p. 287.
3 Loc. cit. 4 Loc. cit.
350 NEKVOUS SYSTEM.
vanced age of the person referred to, seventy-seven years,
would not account for the small weight of the brain, though
the weight is undoubtedly diminished in old persons. We
are not surprised, then, in the tables based upon observa-
tions of thousands of healthy brains of men not remarkable
for great intellect, to find many between fifty-five and sixty
ounces in weight.
As the general result of all the observations upon the
human subject, while we admit that intellectual vigor is in
general coincident with large development of the cerebral
hemispheres, there are certainly many striking exceptions to
this rule when it is applied to individuals.
Location of the Faculty of Articulate Language in a Re-
stricted Portion of the Anterior Cerebral Lobes. — Physiolo-
gists are often slow to accept important facts bearing directly
upon the functions of parts, drawn exclusively from pathol-
ogy, especially when these facts are not capable of demon-
stration by experiments upon the lower animals ; and per-
haps this is due to a certain distrust of the accuracy of
pathological researches as compared with the exact results
of well-executed experimental observations. As regards the
faculty of speech, however, our study must be Confined to
man, the only animal capable of articulate language, and our
data are drawn exclusively from pathology. Some physio-
logical writers are still disposed to regard the location of
the faculty of speech as not definitively settled ; but, from a
careful study of the pathology of aphasia, we are convinced
that there is no point in the physiology of the brain more
exactly determined than that the faculty of speech is located
in a well-defined and restricted portion of the anterior lobes.
This is the more interesting and important, as it is the only
sharply-defined faculty that has been accurately located in a
distinct portion of the brain.
"We do not propose to enter fully into the history of
aphasia, as this belongs to pathology. In the companion-
THE FACULTY OF ARTICULATE LANGUAGE. 351
treatise to this volume, Hammond on the " Diseases of the
Nervous System," the chapter on aphasia not only contains
a full historical account of the disease, but is enriched by
numerous original observations of the most striking char-
acter. The profound acquirements of Dr. Hammond as a
physiologist, and his skill as an original investigator in this
department, lend additional weight to his deductions. In
our references to the bibliography of the subject, we shall
make use of the labors of Dr. Hammond, by whom the lit-
erature has been exhaustively studied.1
Dr. Hammond states that " by aphasia is understood a
condition produced by an affection of the brain by which the
idea of language, or of its expression, is impaired." Certain
cases of this disease present loss of speech because the sub-
ject is incapable of coordinating the muscles used in articu-
lation. The patient has a clear idea of language and of the
meaning of words, and is able to write perfectly well. In
other cases, the patient can neither speak nor express ideas
in writing. In these, the idea of language is lost. In both
of these varieties of the disease, the difficulty is either in the
organ presiding over the faculty of speech or in the connec-
tions of this organ with the muscles concerned in articula-
tion. Thus regarded, aphasia does not include aphonia from
laryngeal disease, or loss of speech such as is observed fre-
quently in hysteria, in the insane, who sometimes refuse to
speak from pure obstinacy, or in cases of paralysis of the
parts immediately concerned in articulation. The whole
history of the disease points to a particular part of the brain
which presides over the faculty of speech.
While we do not propose to treat of the history of apha-
sia, we cannot refrain from quoting a case, detailed in 1T66,
by Pourfour du Petit, which possesses great historical inter-
est, as one of the first, if not the very first, in which the
symptoms now recognized as aphasic were connected with
disease of the left anterior cerebral lobe. "We quote this
1 HAMMOND, Diseases of the Nervous System, Xew York, 1871, p. 166, et *eq.
123
352 NER7OU3 SYSTEM.
case in full, because it seems to have escaped tlie attention
of writers on aphasia :
" Some time after I had made the experiments which I
have just reported, a cavalryman of the garrison, aged thirty-
five years, was brought into our hospital. He had been
seized the day before with paralysis of the entire right side,
which had occurred after a slight pleurisy, from which he
had recovered ; he could move neither the arm, nor the right
leg, nor could he maintain himself in his seat. The lower
jaw was not distorted; he opened and closed the mouth
with facility. He could move the tongue only with a great
deal of difficulty, and could not protrude it from the mouth,
nor pronounce any word.
" The right eye seemed dimmed, and its sight was en-
tirely lost, which I recognized, because, in presenting the
finger, or a stick, very near this eye, he made no movement
of the lid. But as soon as I touched the eye, he closed the
lid. When I presented the finger or a stick to the left eye,
he immediately closed it, though it was not touched.
" He retained sensation on the paralyzed side as well as
on the sound side.
" A month after he had entered the hospital, he moved
the tongue pretty easily, and even protruded it a little from
the mouth, but he could pronounce nothing but non.
"He was attacked with scurvy fifteen days after, and
with abdominal flux, from which he died two months after
his entrance into the hospital, not being relieved by any
remedies.
"His judgment was always perfectly normal during his
disease, and he had no convulsive movements.
" After death I removed the brain and spinal cord. I be-
gan by dissecting the spinal cord, in which I found nothing
abnormal, nor in the right side of the brain. But I found
on the left side, the entire anterior protuberance which con-
tains the internal and superior corpora striata (corps canneles\
the middle ,and the external or inferior, dissolved and con-
THE FACULTY OF ARTICULATE LANGUAGE. 353
verted into a substance resembling the lees of wine. It did
not appear that this part had been swollen, and that it had
become larger than natural.
"Xeither the optic thalami nor the optic nerves were
injured." 1
The great interest of this case will appear when we come
to note the connection between aphasia and the left anterior
lobe of the cerebrum.
As a preliminary to the location of the nerve-centre pre-
siding exclusively over speech, it is necessary to establish the
existence of the power of articulate language as a distinct
faculty; and this is done by cases of disease in which this
faculty seems to be lost, the general mental condition being
unaffected. Passing over the passages in the writings of the
ancients, in which it is stated that the power of speech is
sometimes lost, and even some writers in the beginning of
the present century, who connected this difficulty with lesions
of the anterior lobes of the brain, we come to the observa-
tions of Dr. Marc Dax, who, in 1836, read a paper before
the medical congress at Montpellier, in which he showed im-
pairment or loss of speech in one hundred and forty cases of
right hemiplegia. Dax concluded, from these observations,
that the faculty of articulate language occupies the left ante-
rior lobe. This memoir, however, attracted but little atten-
tion, until 1861, when the discussion was renewed by Broca ;
and since then, Broca, Aubertin, Charcot, Falret, Perroud,
and Trousseau, have reported numerous cases of aphasia
with lesion of the left anterior lobe. In 1863, M. Gr. Dax,
a son of Marc Dax, limited the lesion to the anterior and
middle part of the left anterior lobe. It was further stated,
by Broca and Hughlings Jackson, to be that portion of the
orain nourished by the left middle cerebral artery. This
subject has been more lately investigated by Sanders, Moxon,
Ogle, Bateman, Bastian, Yon Benedict, Braunwart, and
1 POCRFOUR DU PETIT, Fouveau si/steme du cervcau. — Rccueil cT observation*
d" anatomic et de chirurgie, Paris, 1766, p. 74.
354: NERVOUS SYSTEM.
by A. Flint, H. B. Wilbur, E. C. Seguin, and others, in
this country. According to recent observers, the most fre-
quent lesion in aphasia is in the parts supplied by the left
middle cerebral artery, particularly the lobe of the insula,
or the island of Reil ; and it is a curious fact that this part is
found only in man and monkeys, being in the latter very
slightly developed. While we must agree with Dr. Ham-
mond in the statement that the organ of language cannot
be absolutely restricted to these parts, it is none the less
certain that they are most frequently the seat of lesion in
aphasia.
As illustrating the loss of the faculty of speech without
any marked impairment of the intellectual faculties, we can
cite numerous cases recorded by Dr. Hammond. A woman
is described as presenting a countenance remarkably bright
and cheerful, her whole expression being exceedingly intelli-
gent. " She comprehends every word that is said to her,
and attends to all her household duties. Yet she is unable
to utter any words but ' no,' ' yes,' and ( dado.' " l Other
cases are given, in which the intellect seemed to be clear, but
in some, the faculty of speech was lost, and in others, both
the faculty of speech and of writing. One case reported by
Dr. Hammond is so striking that we give it in full :
" The patient was a retired officer of the army, and con-
sulted me in the autumn of 1869 for paralysis, vertigo, and
slight difficulty of speaking, from which he had suffered for
some months. Several years previously he had been under
the care of my friend Dr. Metcalfe, for acute rheumatism,
with cardiac complications. The history of the case pointed
strongly to embolism, and, as the paralysis affected the right
side, I diagnosticated a previous attack of embolism of the
left middle cerebral artery.
" The difficulty of speech was slight ; there were both
amnesic and ataxic aphasia.
" Under the treatment employed he improved very much
1 Op. tit., p. 210.
THE FACULTY OF ARTICULATE LANGUAGE. 355
in the ability to walk, to use his arm, and to speak, so much
so, that he and his friends considered him better than he
had been for several years. But, about six weeks after he
came under my charge, he had another attack. This time
the left side was paralyzed, and there wa's no difficulty of
speech. Galvanism was employed, as before, and he recov-
ered sufficiently to go to Washington City. "While there,
he had a third attack, characterized by right hemiplegia and
aphasia. He soon recovered his power of speech, and soon
afterward had a further attack, involving the left side, and
unattended by aphasia. He recovered under the care of
Dr. Basil Norris, of the army, and soon afterward came
again to New York. A short time after his arrival I re-
quested my friend Prof. Flint . to see him in consultation,
with the special view of having him examine his heart.
This was done with thoroughness, but no abnormal sounds
were detected. While in New York he had two other at-
tacks, during both of which he was delirious ; both were
characterized by hemiplegia. That of the left side was un-
accompanied by aberrations of language ; that of the right
side was attended with ataxic and amnesic aphasia. He for-
got the names of the most' ordinary things, and there were
many words that he could not articulate at all. Thus, when
he wanted a fan, lie called it ca large, flat thing, to make
wind with.' He forgot my name, and could not pronounce
the words beetle, general, physician, and many others. I
sent him to Newport greatly improved, but he had other
attacks there, and finally died in the autumn of the present
year, of, I presume, cerebral softening.
" The interesting features of this case are the concurrence
of hemiplegia and ataxic and annesic aphasia, and the strik-
ing fact that there was no aphasia when the paralysis in-
volved the left side. Thus, according to my views of the
case, the patient had repeated attacks of cerebral embolism.
"When the embolus lodged in the left middle cerebral artery,
there was aphasia accompanied by right hemiplegia ; when
356 NERVOUS SYSTEM.
the embolus obstructed the right middle cerebral artery,
there was left hemiplegia, but no aphasia." 1
An analysis of a large number of cases of aphasia re-
corded by different observers shows that the great majority
occur in connection with right hemiplegia. Dr. Hammond
quotes 243 cases with, right, against 17 cases with left hemi-
plegia. In cases verified by post-mortem examination, 514
occurred when the lesion involved the left, and 31, when it
involved the right anterior lobe. Dr. Hammond cites addi-
tional cases, in 80 of \vhieh the lesion involved the left lobe,
and in 2, the right lobe.
While the above facts show that the cerebral lesion in
aphasia involves the left anterior lobe in the great majority of
cases, there are several instances in which the right lobe alone
was affected ; and this has led physiologists and pathologists
to deny the absolute location of the organ of language on the
left side. Even if we reject a certain number of cases of
aphasia with the brain-lesion limited to the right side, in
wrhich we may suppose that the post-mortem examinations
were incomplete, or the impairment of speech was due, per-
haps, to simple paralysis of muscles, we must admit that, in
a few instances, aphasia has followed injury or disease of the
brain on the right side. Aside from the anatomical arrange-
ment of the arteries, which seem to furnish the greater
amount of blood to the left hemisphere, it is evident that,
as far as voluntary movements are concerned, the right
hand, foot, eye, etc., are used in preference to th/3 left ; and
that the motor functions of the left hemisphere are superior
in activity to those of the right. It would be interesting,
then, to note the physical peculiarities of persons affected
with left hemiplegia and aphasia. Dr. Bateman quotes two
cases of aphasia dependent upon lesion of the right side of
the brain and consequent left hemiplegia, in which the per-
sons were left-handed ; a and these, few as they are, are in-
teresting, as showing that a person may use the right side
1 HAMMOND, op. cit., p. 215. "2 BATEMAN, On Aphasia, London, 1870, p. 164.
THE FACULTY OF ARTICULATE LANGUAGE. 357
of the brain in speech, as in the other motor functions. In
this connection, it may not be uninteresting to note that,
although most anatomists have failed to find any marked
difference in the weight of the two cerebral hemispheres,
Dr. Boyd has shown by an " examination of nearly two hun-
dred cases at St. Marylebone, in which the hemispheres were
weighed separately, that almost invariably the weight of the
left exceeded that of the right by at least the eighth of an
ounce." 1 To conclude our citations of pathological facts bear-
ing upon the location in the brain of the organ of speech,
we may refer to an account, by Dr. Broadbent, of the brain
of a deaf and dumb woman. In this case, the brain was
found to be of about the usual weight, but the left third
frontal convolution was of " comparatively small size and
simple character." a
Taking into consideration all of the pathological facts
bearing upon the subject, it seems certain that, in the great
majority of persons, the organ or part presiding over the
faculty of articulate language is situated at or near the third
frontal convolution and the island of Eeil in the left anterior
lobe of the cerebrum, and mainly in the parts nourished by
the middle cerebral artery. In some few instances, the or-
gan seems to be located in the corresponding part on the
right side. It is possible that, originally, both sides preside
over speech, and the superiority of the left lobe of the brain
over the right and its more constant use by preference in
right-handed persons may lead to a gradual abolition of the
functions of the right side of the brain, in connection with
speech, simply from disuse. This view, however, is hypo-
thetical, but is rendered probable by certain considerations,
among the most important of which is the statement by
1 BOTD, Table of the Weights of the Human Body and Internal Organs. —
Philosophical Transactions, London, 1861, vol. cli., part i., p. 261.
2 BROADBEXT, On the Cerebral Convolutions of a Deaf and Dumb Woman. —
Journal of Anatomy and Physiology, Cambridge and London, 1870, vol. iv., p.
225.
358 NEKVOUS SYSTEM.
Longet, that " one cerebral liemispliere in a healthy con-
dition may suffice for the exercise of intelligence and the ex-
ternal senses." In support of this statement, Longet cites
several cases of serious injury of one hemisphere without
impairment of the intellect.1
Another very important point, which we believe had
never before been noted, is brought forward very strongly
by Dr. Hammond. In what is called the ataxic form of
aphasia, the idea and memory of words are intact, and there
is simply loss of speech from inability to coordinate the mus-
cles concerned in articulate language. Patients affected in
this way cannot speak, but can write with ease and correct-
ness. In the amnesic form of the disease, the idea and
memory of language are lost ; patients cannot speak, and are
affected with agraphia, or inability to write. In cases in
which hemiplegia is marked, the aphasia is of the ataxic
form ; while in cases in which there is no hemiplegia, the
aphasia is amnesic.
" The gray matter of the lobes presides over the idea of
language, and hence over the memory of words. When it
only is involved, there is no hemiplegia, and there is no dif-
ficulty of articulation. The trouble is altogether as regards
the memory of words.
66 The corpus striatum contains the fibres which come from
the anterior column of the spinal cord, and is besides con-
nected wuth the hemisphere. A lesion, therefore, of this
ganglion, or other part of the motor tract, causes paralysis
of motion on the opposite side of the body. The cases I
have detailed show, without exception, that the power of
coordinating the muscles of speech is directly associated
with this hemiplegia. A lesion, therefore, followed by hemi-
plegia and ataxic aphasia, indicates the motor tract as the
seat. If amnesic aphasia is also present, the hemisphere is
ikewise involved." a
1 LONGET, Anatomic et physiologic du systeme nerveux, Paris, 1842, tome i., p.
666, et seq. 2 HAMMOND, op. cit., p. 217.
CHAPTER XIII.
THE CEREBELLUM.
Some points in the physiological anatomy of the cerebellum — Course of the
fibres in the cerebellum — General properties of the cerebellum — Functions
of the cerebellum — Extirpation of the cerebellum in animals — Incomplete
extirpation of the cerebellum — Pathological facts bearing upon the func-
tions of the cerebellum — Andrei's cases — Other cases of disease of the
cerebellum — Connection of the cerebellum with the generative function —
Development of the cerebellum in the lower animals — Paralysis from disease
or injury of the cerebellum.
IT is not necessary, in order to comprehend the functions
of the cerebellum, as far as these are known, to enter into a
full description of its anatomical characters. The points, in
this connection, that are most interesting to us as physiolo-
gists are, the division of the substance of the cerebellum into
gray and white matter ; the connection between the cells
and fibres ; the connection of the fibres with the cerebrum,
and with the prolongations of the columns of the spinal
cord ; and the passage of fibres between the two lateral
lobes. These points, therefore, will be the only ones that
will engage our attention.
o o
Some Points in the Physiological Anatomy of the Cere-
bellum.
As we have seen, in treating of the general arrangement
of the encephalon, the cerebellum, situated beneath the pos-
terior lobes of the cerebrum, weighs about 5*20 ounces av.
in the male, and 4- TO ounces in the female. The propor-
360 NEKVOUS SYSTEM.
tionate weight to that of the cerebrum is as 1 to 8-f- in the
male, and as 1 to 8J in the female. It is separated from the
cerebrum by a strong process of the dura mater, called the
tentorium. Like the cerebrum, the cerebellum presents an
external layer of gray matter, the interior being formed of
white, or fibrous nerve-tissue. The amount of the gray sub-
stance is very much increased by numerous fine convolu-
tions, and is farther extended by the penetration, from the
surface, of arborescent processes of gray matter. Near the
centre of each lateral lobe, embedded in the white substance,
is an irregularly dentated mass of cellular matter, called the
corpus dentatum. The cerebellar convolutions are more
numerous, and the gray substance is deeper, than in the
cerebrum ; and these convolutions are present in many of
the inferior animals in which the surface of the cerebrum is
smooth.
The cerebellum consists of two lateral hemispheres, more
largely developed in man than in the inferior animals, and a
median lobe. The hemispheres are subdivided into smaller
lobes, which it is unnecessary to describe. Beneath the
cerebellum, bounded in front and below by the medulla
oblongata and pons, laterally by the superior peduncles, and
superiorly by the cerebellum itself, is a lozenge-shaped
cavity, called the fourth ventricle. The crura, or peduncles
will be described in connection with the direction of the
fibres.
The structure of the gray substance of the convolutions
presents certain peculiarities. This portion is divided quite
distinctly into an internal and an external layer. The inter-
nal layer presents an exceedingly delicate net-work of fine
nerve-fibres, which pass to the cells of the external layer.
In the plexus of anastomosing fibres, are found numer-
ous bodies like free nuclei, called by Robin, myelocytes.
The external layer is somewhat like the external layer of gray
substance on the posterior lobes of the cerebrum } and is
more or less sharply divided into two or more secondary
COURSE OF THE FIBRES IX THE CEREEELLOI. 361
layers. The most external portion of tins layer contains a
few small nerve-cells and fine filaments of connective tissue ;
and the rest of the layer contains a great number of large
cells, rounded or ovoid, with two or three, and sometimes,
though rarely, four prolongations.1 The mode of connection
between the nerve-cells and the fibres has already been de-
scribed under the head of the general structure of the nervous
system.2
Course of the Fibres in the Cerebellum. — Most anatomical
writers give a very simple description of the course of the
nerve-fibres in the cerebellum. From the gray substance
of the convolutions and their prolongations, the fibres con-
verge to form finally the three crura, or peduncles on each
side. The superior peduncles pass forward and upward to
the crura cerebri and the optic thalami. These connect the
cerebellum with the cerebrum. Beneath the tubercular quad-
rigemina, some of these fibres decussate with the corre-
sponding fibres upon the opposite side ; so that certain of
the fibres of the superior peduncles pass to the corresponding
side of the cerebrum, and others pass to the cerebral hemi-
sphere of the opposite side.
The middle peduncles arise from the lateral hemispheres
of the cerebellum, pass to the pons Yarolii, where they de-
cussate, connecting together the two sides of the cerebellum.
The inferior peduncles pass to the medulla oblongata,
and are continuous with the restiform bodies, which, in turn,
are continuations chiefly of the posterior columns of the
spinal cord.
According to Luys, the fibres from the cortical substance
of the cerebellum all pass to the corpora dentata and there
terminate, being connected with the cells. From the cor-
pora dentata, new fibres arise, which go to form the cerebel-
lar peduncles. Luys does not admit the existence of com-
1 KOLLIKEI^ Elements tfhistologie humaine, Paris, 1868, p. 387, et seq.
9 See page 50.
362 NERVOUS SYSTEM.
missural fibres connecting the two lateral halves of the
cerebellum, and assumes that the decussation between the
two sides takes place through a special system of decussating
prolongations from the cells of the cortical substance, which
he calls " intercortical commissural fibres." 1 This view,
however, is not adopted by the best anatomists ; but nearly
all agree that new fibres arise from the cells of the corpora
dentata and contribute to the formation of the peduncles.
From the above sketch, the physiological significance of
the direction of the fibres, as appears from the most reliable
and generally-accepted anatomical investigations, is suffi-
ciently evident. By the superior peduncles, the cerebellum
is connected, as are all of the encephalic ganglia, with the
cerebrum ; by the middle peduncles, the two lateral halves
of the cerebellum are intimately connected with each other ;
and by the inferior peduncles, the cerebellum is connected
with the posterior columns of the spinal cord. "We shall
see, when we come to study the functions of the cerebellum,
that its connection with the posterior white columns of the
cord is a point of great interest and importance.
General Properties of the Cerebellum. — There is now
no difference of opinion among physiologists, with regard to
the general properties of the cerebellum. We may safely
discard the observations of Zinn and Haller upon this point,
for these experimenters, who conceived that irritation of the
cerebellum produced convulsive movements,2 undoubtedly
stimulated portions of the medulla oblongata ; at least, this
must be assumed, if we accept the results of the more recent
experiments of Flourens, Longet, and many others. Flou-
rens, who made the first elaborate and entirely satisfactory
observations upon the cerebellum in living animals, noted,
1 LUYS, Recherchcs sur le systeme nerveux cerebro-spinal, Paris, 1865, p. 126,
*t *eq.
2 HALLER, Memoires sur la nature sensible et irritable des parties du corps
animal, Lausanne, 1756, p. 208.
FUNCTIONS ,OF THE CEREBELLUM. 363
ji all of his experiments, that lesion or irritation of the cere-
bellum alone produced neither pain nor convulsions ; * and
the same results have followed the observations of Longet 3
and of all modern physiologists who have investigated this
question practically. We have ourselves frequently exposed
and mutilated the cerebellum in pigeons, and have never
observed any evidence of excitability or sensibility. From
these facts, we must conclude that the cerebellum is inex-
citable and insensible to direct stimulation, at least as far as
has been shown by direct observations. It is not impossi-
ble, however, that future experiments may reverse this gen-
erally-received opinion ; particularly in view of the recent ob-
servations of Fritsch and Hitzig, already cited,3 which show
that certain parts of the cerebrum are excitable, and that the
excitability of the encephalic centres rapidly disappears in
living animals, as the result of pain and haemorrhage. We
should note, also, the experiments of Budge, who observed
movements in the testicles and vasa deferentia, in males, and
in the cornua of the uterus and the Fallopian tubes, in
females, following irritation of the cerebellum.4 Hammond
noted movements of this kind in cats just killed, and also
movements of the intestines and of the muscles of the ab-
domen, thigh, and back.5
Functions of the Cerebellum.
There are still the widest differences of opinion among
physiologists, writh regard to the functions of the cerebellum,
mainly for the reason that the experiments upon the lower
1 FLOURENS, Recherches experimentales sur les proprietes et les functions du sys-
teme nerveux, Paris, 1842, p. 18.
li LONGET, Anatomic et physiologie.du systeme nerveux, Paris, 1842, tome i., pp.
783, 734.
3 See page 323.
4 BUDGE, Lehrbuch der specietten Physiologic des Menschen^. Leipzig, 1862, S.
788.
5 HAMMOND, Physiology and Patludogy of the Cerebellum. — Quarterly Journal
of Psychological Medicine^ New York, 1869, vol. iii., p. 223.
364: NESVOUS SYSTEM.
animals, made by Floumis and his followers, though in
themselves sufficiently definite, are apparently contradicted
by pathological observations upon the human subject. There
should be no such discrepancy between well-conducted ex-
periments and carefully-observed cases of disease or injury ;
for it is certain that the functions of the cerebellum present no
essential differences in different animals, at least in man, the
mammalia, and birds. It is necessary, therefore, for the phy-
siologist, by carefully analyzing and correcting the results
obtained by direct experimentation, and by applying to the
study of palological observations the facts elicited by these
experiments, to endeavor to harmonize the real or apparent
contradictions 5 for, as we have often had occasion to remark,
there are no exceptions to the laws to which the functions
of similar classes of animals are subordinated ; and observa-
tions and experiments, apparently discordant, will always be
found, as our positive knowledge advances, to present differ-
ences in the conditions under which the phenomena have
been observed. To apply this to the functions of the cere-
bellum, it may be safely assumed that it is impossible for
this organ to preside directly and exclusively over the mus-
cular coordination in birds and the inferior mammals, and
in man, to possess different functions. "With regard to the
cerebrum, man possesses, not only a higher degree of de-
velopment of certain intellectual faculties than the inferior
animals, but is endowed with others, such as the power of
articulate language. But in man and in the higher orders
of animals, the general properties and functions of the mus-
cular system are essentially the same. To take one of the
most generally-accepted views of the functions of the cere-
bellum, if this be the centre for muscular coordination in
birds and mammals, it has the same office in man, though
it may possess additional functions not found lower in the
scale of animal life. Keeping in view, then, the desirability
of bringing into accord the results of experiments and of
pathological observations, we will first study carefully the
FUNCTIONS -OF THE CEREBELLUM. 365
phenomena which follow injury or extirpation ,of the cere-
bellum in animals.
Extirpation of the Cerebellum in Animals. — In birds,
and in certain mammals in which the operation has been
successful, the more or less complete extirpation of the cere-
bellum is followed by well-marked phenomena, presenting
always the same character, but somewhat differently inter-
preted by various experimenters. Experiments of this kind
were first made by Flourens ; and the accuracy of his obser-
vations has never been successfully controverted, whatever
may have been said of his physiological deductions. In-
deed, there are few if any important points in the phenom-
ena following partial or complete removal of the cerebellum
that escaped the attention of this most accurate observer.
Laying aside, for the present, the deductions to be made
from experiments on animals, the phenomena noted by Flou-
rens and by all who have repeated his observations on the
cerebellum are as follows :
" I extirpated the cerebellum by successive layers in a
pigeon. During the removal of the first layers, there only
appeared slight feebleness and want of harmony in ^the
movements.
" At the middle layers, there was manifested an almost
universal agitation, although there was not added any sign
of convulsion ; the animal executed sudden and disordered
movements ; it heard and saw.
" On the removal of the last layers, the animal, the facul-
ty of jumping, flying, walking, and maintaining the erect
position being more and more disturbed by the preceding
mutilations, lost this faculty entirely.
" Placed on the back, it was not able to recover itself.
Far from resting calm and steady, as occurs in pigeons de-
prived of the cerebral lobes, it became vainly and continually
agitated, but it never moved in a firm and definite manner.
" For example, it saw a blow with which it was threatened,
366 NERVOUS SYSTEM.
wished to avoid it, made a thousand efforts to avoid it, but
did not succeed. If it were placed on its back, it would not
rest, exhausted itself in vain efforts to get up, and finished
by remaining in that position in spite of itself.
" Finally, volition, sensation, perception, persisted ; the
possibility of making general movements persisted also ; but
the coordination of the movements in regular and definite
acts of locomotion was lost." ]
These are the phenomena observed after total extirpation
of the cerebellum. Voluntary movement, sensation, general
sensibility, and the special senses, seem to be intact ; but
there is always a loss of the power of equilibrium, and the
movements executed are never regular, efficient and coor-
dinate. Flourens farther states that animals operated upon
in this way retain the intellectual and perceptive faculties.11
It is exceedingly important now to note the effects of
partial removal of the cerebellum, as these bear directly upon
cases of disease or injury of this organ in the human subject,
in which its disorganization is very rarely complete. We
may illustrate this also by citing two of Flourens's typical
experiments :
" I. I removed by successive layers, all of the upper half
of the cerebellum in a young cock.
" The animal immediately lost all stability, all regularity
in its movements; and its tottering and ~bizarre mode of
progression reminded one entirely of the gait in alcoholic
intoxication.
" Four days after, the equilibrium was less disturbed, and
the progression was more firm and assured.
" Fifteen days after, the equilibrium was completely re-
stored.
"II. I removed, in a pigeon, about the half of the cere-
bellum ; and I removed this organ completely in a fowl.
1 FLOURENS, Reckerches cxperimentales sur les proprietes et les fonctions du sys-
time nerveux, Paris, 1842, p. 37.
8 Op. ci'., p. 134.
FUNCTIONS OF THE CEREBELLUM. 367
" At the end of a certain time, the pigeon had regained
its equilibrium ; the fowl did not regain it at all : the latter
lived nevertheless for more than four months after the opera-
tion." '
These important observations we have repeatedly con-
firmed, and have in our possession the encephalon of a pigeon
which recovered completely after removal of about two-thirds
of the cerebellum, the animal first presenting marked defi-
ciency in coordinating power.
Such are the phenomena observed in experiments upon
the cerebellum in birds, and they have been extended by
Flourens a and others 3 to certain mammals, as young cats,
dogs, moles, 'mice, etc. Our own experiments, which have
been very numerous during the last twelve years, are simply
repetitions of those of Flourens, and the results have been
the same without exception.
The only difficulties in operating upon the cerebellum
arise from haemorrhage and the danger of injuring the
medulla oblongata. The skull is exposed by slitting up the
scalp, and the calvarium is removed in its posterior portion,
penetrating just above the upper insertion of the cervical
muscles. It is well to leave a strip of bone in the median
line, thereby avoiding haemorrhage from the great venous
sinus, though this is not essential. The cerebellum is thus
exposed, and may be removed in part or entirely, by a deli-
cate scalpel or forceps, when the characteristic phenomena
just described are observed. Animals operated upon in this
way feel the sense of hunger and attempt to eat, but when
the movements are very irregular, they are unable to take
food. We have frequently compared the phenomena pre-
sented after removal of the cerebellum with the movements
of a pigeon intoxicated by forcing down the oesophagus a
1 FLOUREXS, op. cit., p. 102.
8 Op. cit., p. 138, et seq.
8 YULPIAX, Lemons sur la physiologic generate et compared du systeme ner-
veux, Paris, 1866, p. 606.
124
368 NERVOUS SYSTEM.
little bread impregnated with alcohol, and they present a
striking similarity.
In view of the remarkable uniformity in the actual results
obtained by different experimenters, it is hardly necessary to
cite all of the observations made upon the lower animals.
The phenomena observed by Flourens have been in the main
confirmed by Fodera,1 Bouillaud,2 Magendie,3 Wagner,4 Lus-
sana,5 Hammond,6 Dalton,7 Yulpian,8 Mitchell,9 Onimus,10
and many others. Certain of these authors differ from Flou-
rens in their ideas concerning the functions of the cerebel-
lum, while they admit the accuracy of his observations.
We will eliminate from the present discussion the experi-
ments made upon animals low in the scale, such as frogs and
fishes, though in some of these, the results are in accord with
the observations just cited upon birds and mammals,11 and
confine ourselves to an interpretation of the phenomena ob-
served after extirpation of the cerebellum in animals in which
the muscular and nervous arrangement is like that of the
I FODERA, Rechcrches experimentales sur le systeme nerveux. — Journal de
physiologic, Paris, 1823, tome iii., p. 193.
* BOUILLAUD, Recherches experimentales tendant d prouver qne le cerveht preside
aux actes de la station et de la progression. — Archives generales de medecine, Paris,
1827, tome xv., p. 68, et seq.
3 MAGENDIE, Precis eleinentaire de physiologie, Paris, 1836, tome i., p.
409.
4 WAGNER, Recherches critiques et experimentales svr les fonctions du cerveau.
— Journal de la physiologie, Paris, 1861, tome iv., p. 258.
5 LUSSANA, Leconn sur les fonctions du cervelet. — Journal de la physiologic,
Paris, 1862, tome v., p. 418.
6 HAMMOND, The Physiology and Pathology of the Cerebellum. — Quarterly
Journal of Psychological Medicine, New York, 1869, vol. iii., p. 230.
7 DALTON, Human Physiology, Philadelphia, 1871, p. 445.
8 VULPIAN, Systeme nerveux, Paris, 1866, p. 618.
9 S. WEIR MITCHELL, Researches on the Physiology of the Cerebellum. — Ameri-
can Journal of the Medical Sciences, Philadelphia, 1869, New Series, No. cxiv., p.
331.
10 ONIMCS, Recherches experimentales, etc. — Journal de I'anafomie, Paris, 1870-
1871, tome vii., p. 652, et seq. Onimus believes that the cerebellum presides
over equilibration rather than general muscular coordination.
II VULPIAN, op. cit., p. 689.
FUNCTIONS OF THE CEREBELLUM. 369
human subject. The results of this mutilation are as defi-
nite, distinct, and invariable", as in any experiments on living
animals, and, taken by themselves, lead inevitably to but
one conclusion.
AVhen the greatest part or the whole of the cerebellum is
removed from a bird or mammal, the animal being, before
the operation, in a perfectly normal condition, and no other
parts being injured, there are no phenomena constantly and
invariably observed except certain modifications of the volun-
tary movements. The intelligence, general and special sen-
sibility, the involuntary movements, and the simple faculty
of voluntary motion, remain. The movements are always
exceedingly irregular and incoordinate ; the animal cannot
maintain its equilibrium ; and, on account of the impossibil-
ity of making regular movements, it cannot feed. This want
of equilibrium and of the power of coordinating the muscles
of the general voluntary system causes the animal to assume
the most absurd and remarkable postures, which, to one ac-
customed to these experiments, are entirely characteristic.
Call this want of equilibration, of coordination, of " muscular
sense," an indication of vertigo, or what we will, the fact
remains, that regular and coordinate muscular action in
standing, walking, or flying, is impossible, although volun-
tary power remain. It is well known that many muscular
acts are more or less automatic, as in standing, and, to a cer-
tain extent, in walking. These acts, as well as nearly all
voluntary movements, require a certain coordination of the
muscles, and this, and this alone, is abolished by extirpation
of the cerebellum. It is true that destruction of the spiral
canals of the internal ear produces analogous disorders of
movement,1 but this is the only mutilation, except division
1 FLOUREXS, Recherches experimentales sur les proprietes et les functions du
tysteme nerveux, Paris, 1842, p. 446.
GOLTZ, Ueber die physiologische Bedeutung der Bogengdnge des Ohrlabyrinths.
— Archivfiir die gesamtnte Physiologic, Bonn, 1870, Bd. Hi., S. 172, et seq.
Taking the results of his experiments as a basis, Goltz proposes the theory
that the semicircular canals are the organs presiding over the sense of equilib-
370 NEKVOUS SYSTEM.
of the anterior white columns of the cord, which produces
any thing like the results of cerebellar injury. Certain im-
portant coordinate muscular movements are well known to
be dependent upon distinct nerve-centres. The acts of res-
piration are presided over exclusively by the medulla oblon-
gata. Deglutition probably has its distinct nerve-centre, as
well as the movements of the eyes. The centre regulating
the coordinate movements in speech is situated in the an-
terior cerebral lobes. None of these peculiar movements
are affected by extirpation of the cerebellum.
If there be a distinct nerve-centre which presides over
the coordination of the general voluntary movements, ex-
periments upon the higher classes of animals show that this
centre is located in the cerebellum. It may be either in the
entire cerebellum or in a certain portion of this organ, but
if it be confined to a restricted part, this has not yet been
determined. If the cerebellum preside over coordination,
as a physiological necessity, the centre must be connected
by nerves with the general muscular system. If this con-
nection exist, a complete interruption of the avenue of com-
munication between the cerebellum and the muscles, we
would naturally expect, would be followed by loss of coor-
dinating power. From the anatomical connections of the
cerebellum, it appears that the only communication be-
tween this 'Organ and the general system is through the
posterior white columns of the spinal cord. TVe have seen
that these columns are not for the transmission of the gen-
eral sensory impressions, and there is no satisfactory evi-
dence that they convey to the encephalon the so-called mus-
cular sense. As regards general sensibility and voluntary
motion, we cannot ascribe any function to the posterior
rium of the head, and thereby of the whole body ; that the pressure of the liquid
in these canals varies with the movements of the head, and that the brain re-
ceives from these, information with regard to the position of the head, and is
able to regulate the general movements accordingly ; and that this information
is inaccurate when the pressure of liquid in the canals is abnormal, the result
being disturbance of the general equilibrium.
FUNCTIONS OF THE CEREBELLUM. 371
white columns, except that when they are divided at several
points, we invariably have want of coordination in the gen-
eral muscular system.1 Whpn the posterior white columns
are disorganized in the human subject, we have loss or im-
pairment of coordinating power, even though the general
sensibility be not affected, as in the disease called locomotor
ataxia.
Confining ourselves still to the interpretation of experi-
ments upon living animals, and leaving for subsequent con-
sideration the phenomena observed in cases of disease or
injury of the cerebellum in the human subject, we are led
to the following conclusions :
There is a necessity for coordination of the movements
of the general voluntary system of muscles, by means of a
nerve-centre or centres.
Whatever other functions the cerebellum may have, it
acts as the centre presiding over equilibration and general
muscular coordination.
The cerebellum has its nervous connection with the gen-
eral muscular system through the posterior white columns
of the spinal cord, a fact which is capable both of anatomical
and physiological demonstration.
If the cerebellum be extirpated, there is loss of coordi-
nating power ; and if the posterior white columns of the
cord be completely divided, destroying the communication
between the cerebellum and the general system, there is
also loss of coordinating power.
When a small portion only of the cerebellum is removed,
there is slight disturbance of coordination, and the disor-
dered movements are marked in proportion to the extent of
injury to the cerebellum.
After extirpation of even one-half or two-thirds of the
cerebellum, the disturbances in coordination immediately
1 The reader is advised to study, in this connection, that portion of the
chapter on the spinal cord as a conductor, which treats of the probable func-
tions of the posterior white columns (see page 289).
372 NERVOUS SYSTEM.
following the operation may disappear, and the animal may
entirely recover, without any regeneration of the extirpated
nerve-substance. This important fact enables us to under-
stand how, in certain cases of disease of the cerebellum in
the human subject, when the disorganization of the nerve-
tissue is slow and gradual, there may never be any disorder
in the movements.
We present the above conclusions, as in our own mind
positive and definite. It is proper to state, however, that
the definition of the function of the cerebellum is one of the
points stated by most physiological authors as doubtful and
unsettled ; and this is so, mainly because many writers have
been unable to harmonize, the experimental facts above de-
tailed, with cases 6f disease or injury of the cerebellum in
the human subject. We conceive that this has frequently
been due to an imperfect study of the pathological facts,
which we now propose to investigate as thoroughly as pos-
sible.
Pathological Facts bearing upon the Functions of the
Cerebellum. — Nearly all writers on the physiology of the
nervous system, while they agree that extirpation of the
cerebellum in the lower animals produces irregularity of
movements, are arrested, as it were, in their deductions, by
the following quotation from Andral, in his report of ninety-
three cases of disease of the cerebellum :
." A more remarkable alteration of movement is noted
in the observation of M. Lallemand. The patient staggered
on his legs, and often came near falling forward. In this
case, the only one which tends to confirm the opinion of
physiologists who regard the cerebellum as the organ of
the coordination of movements, the cerebellum was entirely
transformed into a sac filled with pus." 1
1 ANDRAL, Clinique medicale, Bruxelles, 1834, tome v., p. 501.
The case alluded to is quoted from Lallemand, which we have consulted in
the original, and will refer to again.
FUNCTIONS OF THE CEKEBELLTJM. 373
The bare statement, such as is generally made, that An-
dral collected ninety-three cases of disease of the cerebellum,
only one of which tends to show that this is the organ of
muscular coordination, is sufficient to arrest any physiologist
in the conclusions that would naturally be drawn from ex-
perimental facts ; and nearly all writers have expressed them-
selves as uncertain upon the question of the function of the
cerebellum. Before we go any farther, we wish to settle,
once for all, the physiological bearing of these cases ; and,
with this end in view, have carefully studied, analyzed, and
tabulated them. Out of the ninety-three cases, fifteen were
observed by Andral, and seventy-eight are quoted from
various authors. An analysis of these cases, with reference
to conditions likely to complicate the effects of the cerebellar
disease, etc., is given in the following table :
Analysis of AndrdUs ninety-three Cases of Disease of the
Cerebellum.
(Six Cases, observed ~by Andral.)
Hemiplegia; death in fifty hours . . . . . .1 case.
Hemiplegia ; sudden death 1 "
Hemiplegia ; death hi two days 1 "
Hemiplegia ; associated with cerebral haemorrhage . . . 3 — 6 l cases.
(Seventy -eight Cases, quoted from various Authors.)
Haemorrhage into the cerebellum ; quoted from Serres . . 6 * cases.
quoted from Dance . -If case-
" " " quoted from Bayle . . 1 j u
" " " quoted from Guiot . . 1 § " '
" " " (Serres) hemiplegia . . 2 cases.
" " " (Cazes) coma ... 1 case.
« « " (Morgagni) ; found dead . 1 "
" " " (Sedillot) ; died in fifteen min-
utes . . . . 1 "
(Cafford); died suddenly . 1 "
Haemorrhage (Michelet) ; apoplexy two years before death ; found
an old clot in the right lobe of the cerebellum . . . 1 "
— 16 cases.
1 In these six cases, there was haemorrhage into the cerebellum.
374:
NERVOUS SYSTEM.
Brought forward 16 cases
Haemorrhage (quoted from various authors) ; haemorrhage into
the cerebrum as well as the cerebellum . . . . 9 "
Atrophy of the left cerebral and the right cerebellar hemisphere 2 "
Cases of disease, with paralysis ; quoted from various authors . 9 "
Cases of abscess, with paralysis ; quoted from various authors . 3 "
Cyst (Recamier) ; convulsions 1 case.
Abscess (Laugier) ; convulsions 1 "
Abscess, involving the entire cerebellum (Lallemand) ; want of
coordination1 . . . . 1 "
Cases, quoted from various authors, in which no disturbance was
noted in the movements ; the disease was confined to one
lateral lobe of the cerebellum 5 cases.
Cases of tumor, quoted from various authors, in which there
was paralysis 15 "
Cases of tumor, associated with disease of the cerebrum . . 7 **
Cases of tumor, associated with convulsions ; the descriptions
are very indefinite 9 — 78 cases
(Nine Cases, observed ~by Andral.)
Softening ; herniptegia and convulsions 1 case.
Softening ; hemiplegia and subsequent haemorrhage . . . 1 "
Softening ; hemiplegia and haemorrhage 1 "
Softening ; agitation, like convulsions, of the members . . 1 "
Cyst ; paralysis and convulsions 1 "
Tubercle; hemiplegia ( 1 "
Five small tubercles in one hemisphere of the cerebellum ; move-
ments normal 1 "
Tuberculous mass, the size of a hazel-nut, on one side of the
cerebellum ; movements normal 1 "
Cyst, the size of a hazel-nut, on one side of the cerebellum;
movements normal 1 — 9 cases.
Add cases of haemorrhage, previously cited, observed by Andral, 6 "
Add cases quoted from various authors 73 "
Total cases collected by Andral 2 . . 93 cases.
In six cases, quoted from Serres, marked *, " there were
observed all the signs of violent apoplexy ; nothing in par-
ticular is said with regard to disorders of movement " (An-
dral, op. cit., p. 475). In the case quoted from Dance,
1 This is the single case, noted by Andral, out of the ninety-three, showing
want of coordination.
2 ANDRAL, Clinique medicale, Bruxelles, 1834, tome v., p. 468, et seq.
FUNCTIONS -OF THE CEREBELLUM. 375
marked f? the patient was struck with apoplexy (Andral,
op. tit., p. 475). In the case quoted -from Bayle, marked J,
the patient suddenly lost consciousness, had convulsive move-
ments on the third day, and died in coma, on the fifth day
(Andral, op. cit., p. 476). In the case quoted from Guiot,
marked §, there was " no lesion except effusion of blood in
the median lobe of the cerebellum. The individual who was
the subject of this observation had had an attack of apo-
plexy. Before his attack, he had for some tune a tottering
gait (demarche chancelante), and, after the attack, remained
hemiplegic on the right side " (Andral, op. tit., p. 476).
Let us now carefully review these ninety-three cases of
Andral, which have been hold in terror em over those who
have ventured to argue, from experiments on animals, that
the cerebellum is the coordinator of the muscular movements,
and see how many may properly be thrown out of the ques-
tion !
"We can discard the first six cases, observed by Andral, in
which there was hemiplegia, speedy death, and in three of
which, there was cerebral haemorrhage ; for we could hardly
observe want of coordination in hemiplegics or in cases
complicated with cerebral disease. "We can discard the six
cases, quoted from Serres, in which there was violent apo-
plexy, as well as the case quoted from Dance, with apoplexy
and the case quoted from Bayle, with coma and convulsions.
It is evident that these cases are useless in noting the pres-
ence or absence of coordinating power. "We can discard two
cases (Serres) with hemiplegia ; one (Cazes) with coma ; one,
(Morgagni) found dead ; one (Sedillot) died in fifteen min-
utes ; one (Cafford) died suddenly ; one (Michelet) apoplexy
two years before death, and an old clot in the right lobe
of the cerebellum. This last case is in accord with experi-
ments on animals ; for we have seen that the coordinating
power may be restored after loss of one-half of the cerebel-
lum. "We can discard nine cases quoted from various authors,
in which there was cerebral as well as cerebellar haemor-
376 NERVOUS SYSTEM.
rhage ; two cases of paralysis, with atrophy of one hemi
sphere of the cerebrum and one hemisphere of the cerebel-
lum ; nine indefinitely described cases, with paralysis ; three
cases of abscess, with paralysis ; one case of cyst and one of
abscess, with paralysis ; fifteen cases of tumor, with paraly-
sis ; seven cases, associated with disease of the cerebrum and
paralysis ; nine very indefinitely described cases, associated
with convulsions. Of the remaining cases observed by An-
dral, we can discard one, with hemiplegia and convulsions ;
one, with hemiplegia and subsequent haemorrhage ; one,
with hemiplegia ; one case of cyst, with paralysis and con-
vulsions ; one, of tubercle, with hemiplegia. We can also
discard one case of five small tubercles in one hemisphere
of the cerebellum ; one, of a tuberculous mass, the size of a
hazel-nut, on one side ; one, of a cyst, the size of a hazel-
nut, on one side. These last cases do not present sufficient
destruction of the cerebellar substance to lead us to expect
any disorder in the movements.
• Thus far we have discarded eighty-five cases, leaving
eight to be analyzed. Of these eight cases, in five, it is
simply stated that the movements were unaffected, and that
" one of the lateral lobes of the cerebellum was the seat of
abscess " (Andral, op. cit., p. 500). In view of this bare state-
ment, and the fact that, in animals, recovery of coordinating
power takes place when half of the cerebellum has been
removed, we may throw out these cases as incomplete. It
must be remembered that the abscesses were probably of
slow development ; and if they did not destroy a sufficiently
large portion of the cerebellum to influence the coordinating
power permanently, it is not probable that the functions of
this organ would be at all affected, as there would be no
shock, as in the sudden removal of substance by an operation.
We are thus reduced to three cases ; and in all of these,
the movements were more or less affected. These cases we
will now study as closely as is possible from the details given.
CASE I. — The first case is quoted from Guiot. There was
FUNCTIONS, OF THE CEKEBELLUM. 377
no lesion, except an effusion of blood in the median lobe of
the cerebellum, and there was probably no pressure upon
the peduncles. " The individual who was the subject of this
observation had had an attack of apoplexy. Before the at-
tack, he had for some time a staggering gait (une demarche
chancelante), and, after the attack, he had remained liemi-
plegic on the left side" (Andral, op. tit., p. 476). From
these meagre details, it seems probable that there was a cer-
tain amount of difficulty of coordination, though the descrip-
tion is not as definite as could be desired.
CASE II. — The second case was observed by Andral. A
groom, not quite forty years of age, was brought into the
Maison royale de sante, having suffered from severe head-
ache, vertigo, etc., for fifteen days, which finally became
fixed at the occiput. During the first three days in the hos-
pital, " he was in a continual state of agitation ; the move-
ments of the members, on the right as well as the left
side, were sometimes so 'brusques and disordered that they
resembled convulsive movements." Soon the respiration
became disturbed, and he died in asphyxia. " Upon post-
mortem examination, there was found general injection
of the meninges ; nothing particular in the cerebral hemi-
spheres; a moderate quantity of serum in the ventricles;
reddish softening of the left hemisphere of the cerebellum in
its posterior and inferior half; no other lesion" (Andral,
op. tit., p. 490).
The only marked symptom relating to the movements in
this case was a certain amount of irregularity and convulsive
action of the muscles, while the patient was in bed. The
case is not strong in its bearings, either for or against the
coordination-theory ; for there must have been a great
amount of irritation of the encephalic centres, and it would
certainly be difficult to note disturbance of equilibration or
of coordination in a patient confined to the bed.
The third case is quoted by Andral from Lallemand, and
is taken by Lallemand from Delamare.
3T8 NERVOUS SYSTEM.
CASE III. — " M. Guerin, vicar at Gezeville, forty-six years
of age, of a good temperament, strong, and corpulent, with
a good appetite, complained of a dull pain, which finally be-
came acute, under the frontal bone. For a year he experi-
enced attacks of vertigo and vomiting, without fever. He
staggered on his legs, and was often near falling forward.
The treatment employed was antiphlogistic and derivative."
On post-mortem examination, the cerebrum was found
entirely healthy, but the envelop of the cerebellum was col-
lapsed, folded, and only contained about the half of an egg-
shell full of a brown and fetid, lymphatic*o-purulent liquid.1
This case, as far as the description goes, shows marked
difficulty in equilibration or coordination.
If the reader have carefully studied the foregoing analysis
of Andral's cases, he will see that eighty-five may be thrown
out altogether, leaving but eight ; and of these eight cases,
five are so imperfectly described, and the disorganization of
the cerebellum is so restricted, that they may also be disre-
garded. The ninety-three cases are thus reduced to three.
Of these three cases, in two, it is uncertain whether or not
there were deficiency of coordinating power ; and in one, the
difficulty in equilibration or coordination was distinctly noted.
This, we conceive, disposes of the much-quoted ninety-three
cases of Andral ; and they are certainly not opposed to the
view that the cerebellum is the organ of equilibration or
muscular coordination.
In addition to the cases collected by Andral, there are
numerous other instances on record of disease confined to
the cerebellum.
CASE IV. — An interesting case of disease of the cere-
bellum was reported by Gall, in 1823.3 This patient " com-
plained for several months of a very disagreeable sense of
pressure at the nucha, and a tendency to fall forward as if
1 LALLEMAND, Recherche* analomico-pathologiques sur rencephale, Paris, 1823,
tome ii., p. 39.
2 GALL, Sur Icsfonctions du cerveau, Paris, 1823, tome Hi., p. 341.
FUNCTIONS OF THE CEREBELLUM. 379
he saw a precipice at his feet. Several physicians attributed
these symptoms to haemorrhoids ; for myself, I concluded
that there was an organic disease in the brain. Several
months after, the patient died, and we found on the ten to-
riuni a fleshy mass two inches in diameter, which had com-
pressed the cerebellum."
CASE Y. — In 1826, Fetiet reported a case of disease, in
which the cerebellum was entirely destroyed, its tissue being
broken down into a sort of whitish ~bouillie* The cerebrum
was healthy. ' The observation was made in 1796. The pa-
tient, before death, was observed to present a remarkable
tendency to walk backward. He rose from his seat with
difficulty, and, once erect, the first movements of the feet
were lateral, and he finally walked by moving the feet from
before backward. His locomotion consisted simply in pass-
ing from his own to an adjoining bed in the ward, a distance
of about six feet.
CASE VI. — One of the most remarkable cases, and the one
most frequently quoted by physiological writers, was report-
ed by Combette, in 1831. a This patient, Alexandrine La-
brosse, in her seventh year, was seen by M. Miquel. Since
the age of five years only had she been able to sustain her-
self on her feet. M. Miquel was struck with her slight de-
velopment and the feebleness of the extremities. At the
age of nine and a half years, she was admitted into the Or-
phelins. ""\Vhen spoken to, she answered with difficulty
and hesitation. Her legs, although very feeble, enabled her
still to walk, but she often fell." She was first seen by M.
Combette, in January, 1831. She had then kept the bed for
three months; was constantly lying on the back, nd could
scarcely move the legs ; she used her hands with ease. She
died of some intestinal disorder, March 25, 1831. On post-
1 PETIET, Journal de physiologic, Paris, 1826, tome yi., p. 162, et seq.
2 COMBETTE, Observation d"une jeune Jille, morte dans sa onzieme annee, chcz
laquelk il y avail absence complete du cervelet, dcs pedoncules posterieures et de la
protuberance annulaire. — Journal de physiologic, Paris,. 1831, tome xi., p. 27, etseq.
380 NERVOUS SYSTEM.
mortem examination, " in place of the cerebellum there was
a cellular membrane, gelatiniform, semicircular, from eigh-
teen to twenty lines in its transverse diameter." There was
no trace of the pons Yarolii. Combette states that Alex-
andrine Labrosse was able to walk for several years, always,
it is true, in an uncertain manner ; later, her legs became
more and more feeble, and finally she ceased to be able to
sustain her weight. She had the habit of masturbation. Com-
bette further states that this observation is not in accord
"with the experiments of Flourens, which tend to show
that the cerebellum is the regulator of movements." The
encephalon was also examined by Guillot, who noted ab-
sence of the cerebellum and of the pons.
This case is somewhat imperfect, as it was not seen by
Combette until the patient had kept the bed for three
months. By some writers, it is quoted in favor of, and by
some, in opposition to the view that the cerebellum coordi-
nates the muscular movements. It was not a case of simple
disease of the cerebellum, as the pons and the posterior pe-
duncles were also absent. It was noted, before the case was
seen by Combette, that the patient walked in an uncertain
manner and often fell.
Several cases of injury of the cerebellum are reported by
Larrey.1
CASE YII. — One case is described, in which the patient
was struck by a ball from a blunderbuss, which grazed the
occipital protuberances. There was no disturbance of move-
ment. The patient died on the thirty-ninth day, in opisthot-
onos. On post-mortem examination, "the occipital bone
had sustained a considerable loss of substance ; the slit into
the dura mater, to which we have alluded, corresponded to
the centre of the right lobe of the cerebellum, which was
sunk downward and was of a yellowish color, but free from
suppuration or effusion. The medulla oblongata and spinal
1 LARREY, Injuries of the Cerebellum. — Observations on Wounds, etc., Phila-
delphia, 1832, p. 199, et seq.
FUNCTIONS X>F THE CEEEBELLUM. 381
marrow bore a dull,- white aspect, were of greater consist-
ence than is natural, and had lost about a quarter of their
size ; the nerves arising from them appeared to us also
to be in a state of atrophy near their origin" (Larrey,
op. cit., p. 207).
CASE VIII. — Another patient was struck by a piece of
wood on* the right side of the head. He was found dead a
little over three months after the injury. " The right hemi-
sphere of the cerebellum was entirely disorganized by an
abscess which pervaded its whole substance " (Larrey, op.
cit., p. 210). No disturbances of movement were noted.
CASE IX. — Another patient had erysipelas following a
fall on the side of the head, and abscess. He lived for three
or four months. Five or six weeks after the injury, he had
severe pains in the occiput, and, " when standing he could
with difficulty only preserve his equilibrium." On post-
mortem examination, the deep-seated vessels of the cere-
brum were found injected. "We found, in the left lobe
of the cerebellum, about three tablespoonfuls of pus of a
whitish and gelatinous aspect, which had encroached upon,
or rather displaced entirely, the hemisphere of the cerebel-
lum ; this purulent substance was enveloped within the pia
mater, which had acquired a somewhat firmer consistence,
and, as in the subject of the preceding case, assumed a pearly
color. The other half of the cerebellum was shrivelled, and
the medullary substance forming the arbor vitse was of a
grayish color and very dense " (Larrey, op. cit., p. 211).
The first of these cases was found by Larrey to be asso-
ciated with extinction of sexual appetite, and atrophy of the
organs of generation. In the first two cases, judging from
the results of experiments on animals, there was not enough
injury of the cerebellum to necessarily influence the power
of coordination. In the last case, there was difficulty in
equilibration, but also some paralysis.
A number of cases, which it is unnecessary to detail
fulry, are cited by Wagner, in the Journal de la physiologic,
382 NEKVOTJS SYSTEM.
in which tottering gait and want of equilibration or of mus-
cular coordination were noted, in connection with greater or
less disorganization of the cerebellum.1 In the same jour-
nal, is a brief note of a case, reported by Laborde, in which
there was a large cyst in the cerebellum, with incomplete
paraplegia and " want of coordination of the movements of
progression." 2
CASE X. — A most remarkable and carefully-observed case
of atrophy of the cerebellum was reported by Dr. Fiedler,
in 18G1.3 The subject of this observation, a man, aged about
fifty years, had remarkable peculiarities in his movements
for thirty years. After the age of twenty years, it is stated
that " he could no longer walk with as much certainty as
before; the gait was staggering (taumelnd). . . . Not only
in the house, but also in the street, the patient often fell, so
that he was very frequently taken for a drunkard, and was
either carried home or taken to the police-station. It is said
that he never had drunk spirituous liquors.
" Sometimes the patient walked backward, but only a few
steps. He never had any turning movements ; the gait was
always tottering (wacklig) and slow " (Fiedler, op. tit., p.
251). He never fell forward, but always on the back. On
post-mortem examination, the cerebrum was found healthy,
" but the cerebellum was atrophied, especially at its posterior
and inferior portion, and was reduced in size at least one-
half" (Fiedler, op. cit., p. 258). This case presented the
phenomena of defective coordination to a marked degree.
Nothing is said of vertigo.
CASE XI. — In an elaborate article by Lussana, on the
cerebellum, a case is quoted from Pourfour du Petit, in
which a soldier, who received a gunshot-wound traversing
1 WAGNER, Recherches critiques et experimentales sur les fonctions du ccrveau.
— Journal de la physiologic, Paris, 1861, torr.e iv., p. 386.
8 Ibid., p. 637.
8 FIEDLER, Ein Fall von Verkummerung des Cerebellum. — Zcitschrift far ra*
tionelle Medicin, Leipzig und Heidelberg, 1861, Bd. xi., S. 250, et seq.
FUNCTIONS OF THE CEKEBELLUM. 383
the left lobe of the cerebellum, immediately presented " a
great disorder in his movements."
Among the most striking of the cases of disease of the
cerebellum, are two observed by Vulpian.
CASE XII. — The first was a woman, forty-nine years of
age, in the hospital of la Salpetriere. " All of the move-
ments were preserved, but locomotion was most irregular
and difficult ; she could only walk in the most lizarre man-
ner, resting on a chair which she placed before her at every
step, and, in spite of her efforts at equilibration, she often
fell." This patient, however, retained great muscular power.
On post-mortem examination, " the cortical gray substance
of the cerebellum was found entirely atrophied : all the
nerve-cells of this layer had disappeared." There was con-
siderable reduction in the size of the cerebellum. The cor-
pora dentata were perfectly preserved, " showing that these
parts, at all events, have but a slight office in coordination." 8
CASE XIII. — The second case presented an old softening,
about the size of a hazel-nut, destroying a corresponding
amount of the cerebellar substance of one of the hemispheres.
The corpus dentatum was completely destroyed. This wom-
an " walked well, but it appears nevertheless that she vacil-
lated very slightly in her gait, without, however, a tendency
to fall." 3
"We have thus cited quite a number of cases of disease
confined to the cerebellum, in which there was marked dis-
turbance in the muscular movements ; but there are others,
in which the movements were unaffected. As an example
of the latter, we may refer to a case cited from Bouvier, by
Prof. Hammond.
CASE XIY. — In this case, the movements of the limbs
were all preserved. On post-mortem examination, there
was found an abscess involving the two outer thirds of the
1 LUSSAXA, Lemons sur les fonctions du cervellet. — Journal de la physiologic,
Paris, 1862, tome v., p. 429.
3 VULPIAN, Systeme ncrveiix, Paris, 1866, p. 629. 3 Op. tit., p. 632.
125
384 NERVOUS SYSTEM.
left hemisphere of the cerebellum ; the walls of this cavity,
which contained several tablespoonfuls of pus, were soft-
ened.
" As M. Bouvier remarks, a circumstance of great inter-
est connected with this case is the entire absence during life
of any symptoms indicating an augmented sensibility, loss
of equilibrium, or excitation of the genital organs." x
With regard to this case, it is evident that the disease of
the cerebellum was of slow development and did not involve
enough of its substance to necessarily interfere with its func-
tions, as has been clearly shown in other pathological cases
and in experiments upon animals.
Prof. Hammond also reports two interesting cases which
came under his own observation.2
CASE XY. — " In 1851, a Mexican shepherd was attacked
near Cebolleta, in !N"ew Mexico, by Navajo Indians. He
managed to escape, but in fleeing from his enemies received
an arrow-wound in the posterior part of the head. He was
on horseback, and, though stunned by the blow, maintained
his seat in the saddle. So firmly was the arrow implanted
that the shaft became detached by his efforts to remove it,
leaving the head of the weapon in the skull. I saw him
about two hours subsequently. He was then in full posses-
sion of his senses and was suffering no pain. There were,
however, constant vertigo and nausea, together with a sen-
sation, as he described it, as if his head were balanced on a
very delicate point, and the least inclination to one side
or the other would cause it to fall off. On examining the
wound, I found the arrow still sticking in the bone, and I
had to use considerable force before I could remove it. It
had entered to the extent of an inch and a half — a little be-
low and to the left of the occipital protuberance — wounding
the left lobe of the cerebellum. The vertigo continued all
1 HAMMOND, The Physiology and Pathology of the Cerebellum. — Quarterly
Journal of Psychological Medicine, New York, 1869, vol. iii., p. 237.
8 Loc. crit.
FUNCTIONS OF THE CEREBELLUM. 385
that night, but the nausea and vomiting stopped in the
course of a few hours.
" The next day he attempted to walk, but was obliged to
desist on account of the vertigo. ' He felt,' he said, ( as if
he were drunk,' and he staggered just like a drunken man.
This feeling of vertigo continued for several weeks, lasting
all through the period of suppuration. Gradually it disap-
peared, though even after the lapse of a year he felt giddy
on making any unusual exertion. At no time was there any
difficulty in coordinating the muscles of the upper or lower
extremities. The latter were simply affected through the ver-
tigious sensation. The sensibility was unaffected through-
out the whole progress of the case.
CASE XVI. — " The other case was that of a man who, for
several months, had suffered with vertigo, occasional con-
vulsions, attacks of nausea and vomiting, and a constant and
violent pain affecting the back of the head. These symp-
toms had come on subsequently to a severe blow which he
had received on the back of the head, in consequence of
raising himself too soon while the horse he was riding was
passing under a low archway.
" When this man attempted to walk he reeled and stag-
gered as if he were drunk, but his movements were very
different from those which we now recognize as character-
izing locomotor ataxia. The upper extremities, and the or-
gans of speech, were not affected ; he had the entire control
of his legs when lying down, and there was no diminution
of sensibility anywhere. At last he became paraplegic, and
died in a convulsion. The post-mortem examination showed
the existence of an abscess, which had obliterated nearly the
whole of the left lobe of the cerebellum."
The interpretation of these two cases depends, apparently,
upon the ideas concerning the functions of the cerebellum,
with which they are regarded. We should consider them
as very strong evidence that the cerebellum regulates equi-
libration and muscular coordination. Prof. Hammond re-
386 NERVOUS SYSTEM.
gards them as in accordance with his idea, that injury of
the cerebellum does not affect coordination, but simply pro-
duces vertigo. It remains for the reader to judge whether
or not the phonomena observed indicate want of coordinating
power.
We now come to the main question, whether or not, in
view of the results of experiments on animals and the phe-
nomena observed in cases of disease or injury of the cere-
bellum, this nerve-centre presides over coordination of ac-
tion of the muscles, which is certainly necessary to equili-
bration, except the muscles of the face and those concerned
in speech. This question seems to us to be capable of a
definite answer.
Every carefully-observed case that we have been able to
find, in which there was uncomplicated disease or injury of
the cerebellum, provided the disease or injury involved more
than half of the organ, presented great disorder in the gen-
eral movements, particularly those of progression. AVe have
collected the more or less complete reports of sixteen cases.
In Case II., there was softening of one-half of one hemisphere,
and remarkable convulsive movements. In Case VI., the
one so often quoted from Combette, the gait was uncertain,
with frequent falling ; there was incomplete paralysis ; but,
in addition to the absence of the cerebellum, there was no
pons Yarolii. In Case VII., there was no disturbance of
movement, and there was partial degeneration of one lateral
lobe. In Case VIII., there was no disturbance of move-
ment, and disorganization of one lateral lobe of the cerebel-
lum. In Case XIII., there was slight loss of substance in
one lateral lobe of the cerebellum, and slight " vacillation "
in the movements. In Case XIV., there was an abscess in-
volving two-thirds of one lateral lobe, and the movements
of the limbs were preserved. In Cases I., III., IV., V., IX.,
X., XI., XII., XV., XVI., ten out of sixteen, there was
difficulty in muscular coordination, which was invariably in
FUNCTIONS OF THE CEREBELLOI. 3S7
direct ratio to the amount of cerebellar substance involved
in the disease or injury. We do not make the reservation,
that more than half of the cerebellum must be destroyed in
order necessarily to produce difficulty in muscular coordina-
tion, on purely theoretical grounds, but regard this point as
positively demonstrated by experiments on animals. These
experiments show that one-half of the organ is capable of
performing the function of the whole. AVe have an analogy
to this in the action of the kidneys, one of which is sufficient
for the elimination of the effete constituents of the urine,
after the other has been removed.
Notwithstanding the contrary views of many physiologi-
cal writers, we are firmly convinced, from experiments and
a careful study of pathological facts, that there is no one
point in the physiology of the nerve-centres more definitely
settled than that the cerebellum presides over equilibration
and the coordination of the muscular movements, particu-
larly those of progression. In this statement, we make ex-
ceptions in favor of the movements of respiration, degluti-
tion, of the face, and of those concerned in speech, as well as
the involuntary movements generally. As another example
of a nerve-centre presiding over muscular coordination, we
have the instance of the portion of the left anterior lobe of
the cerebrum, which coordinates the action of the muscles
concerned in speech.
The theory that the disordered movements which follow
injury of the cerebellum are due simply to vertigo is not
tenable. In only three of the cases cited, is vertigo men-
tioned; and in two, the word vertigo seems to be used
rather as an explanation of the phenomena observed, than
in their simple description. There is a disease involving the
semicircular canals and other parts of the internal ear,
called Meniere's disease, in which there is marked want of
equilibration and muscular coordination, attended with, and
probably dependent upon vertigo. The vertigo is always
very distinct, and is mentioned in all of these cases ; and
388 NERVOUS SYSTEM.
though, it is less in the recumbent posture, it is never en-
tirely absent. A very elaborate article on certain affections
of the inner ear, including Meniere's disease, with numer-
ous illustrative cases, was published by Dr. Knapp, in the
Archives of Ophthalmology and Otology, New York, 18T1,
vol. ii., No. i. A careful study of these cases, comparing
them with the cases of deficient coordination from disease of
the cerebellum, cannot fail to show a great difference be-
tween the phenomena following cerebellar disease and the
muscular phenomena due to well-marked and persistent
vertigo.1
Connection of the Cerebellum with the Generative Func-
tion.— The fact that the cerebellum is the centre for equili-
bration and the coordination of certain muscular movements
does not necessarily imply that it has no other functions.
The idea of Gall, that " the cerebellum is the organ of the
instinct of generation," 2 is sufficiently familiar ; and there
are numerous facts in pathology that show a certain relation
between this nerve-centre and the organs of generation,
though the idea that it presides over the generative function
is not sustained by the results of experiments on animals,
or by facts in comparative anatomy.
In experiments on animals in which the cerebellum has
been removed, there is nothing pointing directly to this part
as the organ of the generative instinct. Flourens removed a
great part of the cerebellum in a cock. The animal survived
for eight months. It was put several times with hens, and
always attempted to mount them, but without success, from
want of equilibrium. In this animal, the testicles were
enormous.3 This observation has been repeatedly confirmed,
and there are no instances in which the cerebellum has been
1 KNAPP, A Clinical Analysis of the Inflanvnatory Affections of the Inner Ear,
New York, 1871.
2 GALL, Sur les fonctions du cerveau, Paris, 1825, tome Hi., p. 245.
3 FLOURENS, Systeme nerveux, Paris, 1842, p. 163
FUNCTIONS OF THE CEREBELLUM. 389
removed with apparent destruction of sexual instinct. In a
comparison of the relative weights of the cerebellum in stal-
lions, mares, and geldings, Leuret found that, far from being
atrophied, the cerebellum of geldings was even larger than
in either stallions or mares.1
In the numerous cases of disease or injury of the cere-
bellum, to which we have already referred, there are some,
in which irritation of this part has been followed by persistent
erection and manifest exaggeration of the sexual appetite,
and others, in which its extensive degeneration or destruction
has apparently produced atrophy of the generative organs
and total loss of sexual desire. There are also certain cases
of this kind which we have not yet cited. Serres gives the
history of several cases, in which irritation of the cerebellum
was followed by satyriasis or nymphomania, but in other
cases, there were no symptoms referable to the generative
organs.3 In the case reported by Combette, the patient had
the habit of masturbation.3 Dr. Fisher, of Boston, gives an
account of two cases of diseased or atrophied cerebellum, with
absence of sexual desire, and one case of irritation, with
satyriasis.4 Similar instances are given by other writers,
which it is unnecessary to detail. We have already cited
the observations of Budge and of Hammond, in which me-
chanical irritation of the cerebellum was followed by move-
ments of the uterus, testicles, etc.6 For other citations bear-
ing upon the connection between the cerebellum and the
generative function, the reader is referred to the elaborate
memoir by Prof. Hammond.6
1 LEURET, Ana'omie comparee da sysleme nerveux, Paris, 1839-1857, tome i.,
p. 429.
2 SERRES, Sur les maladies organiques du cervelet. — Journal de physiologic,
Paris, 1822, tome ii., p. 172, et seq., and p. 249, et seq.
3 Journal de physiologic, Paris, 1831, tome xi., p. 30.
4 FISHER, Contributions Illustrative of the Functions of the Cerebellum. — Amer-
ican. Journal of tjie Medical Sciences, Philadelphia, 1838, No. xlv., p. 352, et seq.
5 See page 363.
6 Quarterly Journal of Psychological Medicine, New York, 1869, vol. Hi., p.
219, et seq.
390 NERVOUS SYSTEM.
Although there are many facts in pathology which are
opposed to the view that the cerebellum presides over the
generative function, there are numerous cases which go to
show a certain connection between this portion of the central
nervous system and the organs of generation in the human
subject. But this is all that we can say upon this im-
portant point ; certain it is that the facts are not sufficiently
numerous, definite, and invariable, to sustain the doctrine
that the cerebellum is the seat of the sexual instinct.
Development of the Cerebellum in the Lower Animals. —
The study of the comparative anatomy of the cerebellum has
little physiological interest, except in so far as it bears upon
our knowledge of its physiology. From this point of view,
there is little to be said concerning its development in the
animal scale. We can hardly establish a definite relation
between this particular part of the encephalon and the corn-
plicated character of the muscular movements ; for, as we
pass from the lower to the higher orders of animals, we have
other parts of the brain, as well as the cerebellum, devel-
oped in proportion to the increased complexity of the mus-
cular system. !Nor can we connect the comparative anatomy
of the cerebellum with the ideas of the functions of this organ
in connection with generation. The amphioxus lanciolatus
has no cerebellum, and this organ, therefore, is not indis-
pensable to generation. In some animals remarkable for
salacity, the cerebellum is not unusually large ; and facts of
this kind might be multiplied ad infinitum.
Paralysis from Disease or Injury of the Cerebellum. — It
is not unusual to observe disorganization of a considerable
amount of cerebellar substance without paralysis ; and,
indeed, we are inclined, upon this point, to adopt the view
advanced by Yulpian, that, of itself, disease of the cerebellum
is not attended with hemiplegia, this condition obtaining
only when the peduncles, the pons; or the motor tracts of
PARALYSIS FROM DISEASE OF THE CEREBELLUM. 391
the cord are directly or indirectly involved.1 As far as the
physiology of the cerebellum bears upon this point, there is
no reason why simple disease of its substance should produce
hemiplegia. As in cerebral affections disease of the hemi-
spheres is followed by hemiplegia, as the rule, only when the
corpora striata, the optic thalami, or the pons, is involved,
either by compression or disorganization, so in disease of the
cerebellum, there must be some disturbance of the motor
tracts.
It is a curious fact, also, that in certain cases of disease
of the cerebellum, without any affection of the cerebrum, in
which hemiplegia exists, the paralysis occurs on the opposite
side of the body, while in others, it is on the same side as the
cerebellar lesion. According to Yulpian, the hemiplegia is
direct or crossed, the situation of the paralysis depending
upon the parts of the motor tracts that are compressed. In
simple softening of the substance of the cerebellum, as we
have just remarked, there is, of necessity, no paralysis, but
haemorrhage or tumors may impinge upon one or another
of the motor tracts of the encephalon or the cord.8
In certain of the cases collected by Andral, there was a
lesion of one lateral lobe of the cerebellum, associated with a
lesion of the cerebral hemisphere of the opposite side. In
these cases, the paralysis did not affect both sides of the body,
but was always situated on the side opposite to the lesion of
the cerebrum, the same side as the cerebellar disease.8
AVe have thus only discussed those views with regard to
the functions of the cerebellum which are supported by ex-
perimental or pathological facts, and have not touched upon
the vague and unsupported ideas advanced by various writers
before the publication of the remarkable observations of
Flourens. There is 110 proof that the cerebellum is the organ
1 YCLPIAN, Systeme nerveux, Paris, 1866, p. 608.
2 TULPIAX, loc. cit.
3 ANDRAL, Clinique mtdicale, Bruxelles, 1834, tome v., p. 481.
392 NERVOUS SYSTEM.
presiding over memory, the involuntary movements, general
sensibility, or the general voluntary movements. The only
view that has any positive experimental or pathological
basis is that it presides over equilibration and the coordina-
tion of certain muscular movements, and is in some way
connected with the generative function.
CHAPTEE XIY.
GANGLIA AT THE BASE OF THE ENCEPHALON.
Corpora striata — Optic thalami — Tubercula quadrigemina, or optic lobes — Gan-
glion of the tuber annulare — Medulla oblongata — Physiological anatomy of
the medulla oblongata — Functions of the medulla oblongata — Connection
of the medulla oblongata with respiration — Vital point — Connection of the
medulla oblongata with various reflex acts — Rolling and turning movements
following injury of certain parts of the encephalon— General properties of
the peduncles.
AT the base of the encephalon, are found several collec-
tions of gray matter, or ganglia, some of which have func-
tions distinct from those already described in connection
with the cerebrum and the cerebellum ; but most of them
are so difficult of access in living animals, that we possess
very little definite information, even with regard to their
general properties. We have, however, a tolerably complete
knowledge of the functions of the medulla oblongata and
the tubercula quadrigemina, and have some idea of the physi-
ology of the tuber annulare ; but the functions of the corpora
striata, optic thalami, ventricles, pineal gland, peduncles,
etc., are not at all understood, and the speculations of the
older writers, with the indefinite experiments of modern
physiologists, upon these parts, will be passed over very
briefly.
Corpora Striata.
These bodies are somewhat pear-shaped, and are situated
at the base of the brain, partly without the cerebral hemi-
spheres and partly embedded in their white substance.
394 NEKVUPS SYSTEM.
Their rounded base is directed forward, and the narrower
end, backward and outward. Their external surface is gray,
and they present, on section, alternate striae of white and
gray matter, wrhich appearance has given them the name of
corpora striata. Between the narrow extremities of these
bodies, are situated the optic thalami.
There is very little to be said with regard to the func-
tions of the corpora striata. Longet has found them com-
pletely inexcitable and insensible to mechanical irritation.1
The idea of M agendie, that a tendency to backward move-
ments resided in these bodies, while the cerebellum exerted
an antagonistic action, is not sustained by experiments.8
When they are removed, disturbing the hemispheres as little
as possible, there appears to be no paralysis, either of motion
or sensation.3
"We have obtained a little more information regarding
the functions of the corpora striata, from cases of cerebral
haemorrhage in the human subject, than from experimental
investigations. In apoplexy, when the corpus striatum on
one side is alone involved, there is paralysis of motion of the
opposite lateral half of the body, the general sensibility usual-
ly being unaffected. Facts of this kind show that the action
of the corpora striata is crossed ; and they further illustrate
their connection with the motor tract from the hemispheres.
There is no reason to suppose that the corpora striata are
the centres of olfaction, as was at one time thought, for they
are sometimes absent in animals possessing very large olfac-
tory nerves, and are very largely developed in the cetacea,
in which the olfactory apparatus is rudimentary.4
Optic Thalami.
From their name, we should infer that the optic thalami
have some important function in connection with vision ;
1 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 419.
2 MAGENDIE, Precis elementaire de physiologic, Paris, 1836, tome i., p. 404.
8 LONGET, loc. cit. 4 LONGET, loc. cit.
OPTIC THALAm. 395
but they serve merely as beds for the optic commissures, and
give to the nerves but very few fibres. They are oblong
bodies, situated between the posterior extremities of the
corpora striata, and resting upon the crura cerebri on the
two sides. They are white externally, and, in their interior,
present a mixfure of white and gray matter. Longet has
destroyed them upon the two sides, carefully avoiding injury
of the optic tracts, and noted* no interference with vision or
the movements of the iris.
The optic thalarni seem, from experiments upon animals,
to have a peculiar crossed action upon the muscular system.
While their mechanical irritation produces neither pain nor
convulsive movements, showing that they arc insensible and
in excitable, the extirpation of one optic thalamus produces
enfeeblemeiit of the muscles of the opposite lateral half of
the body, without actual paralysis.1 "When both have been
removed, there is general debility of the muscular system.
It is unnecessary to refer to other experiments upon these
parts, which have been very indefinite in their results, or to
allude to the "circular" movements produced by lesion
upon one side, involving also the crus cerebri ; for, beyond
the statement just made, the function of the optic thalami
is unknown.
"We derive but little information concerning the optic
thalami from cases of cerebral haemorrhage in the human
subject ; for it is not common to have disease involving
these parts and not affecting other centres. In some cases
of lesion limited to the optic thalamus on one side, there is
paralysis of sensation of the opposite lateral half of the body,
without actual paralysis of motion, though the movements
are generally feeble. "When the brain-lesion involves both
the corpus striatum and the optic thalamus on one side,
which is more common, there is paralysis of motion, with
loss or disorder of sensibility, on the opposite side of the
body. These facts illustrate, to a certain extent, the ana-
1 LGXGET, Traite de jthysioloffie, Paris, 1869, tome iii., pp. 412, 413.
NERVOUS SYSTEM.
tomical connection of the optic thalami with the sensory
tracts, though, in experiments on animals, destruction of
these parts does not necessarily affect the general sensibility.
Tubereula Quadrigemina.
These little bodies, sometimes called the optic lobes, are
rounded eminences, two upon, either side, situated just be-
hind the third ventricle. The anterior, called the nates,
are the larger. These are oblong and of a grayish color ex-
ternally. The posterior, called the testes, are situated just
behind the anterior. They are rounded, and rather lighter
in color than the anterior. Both contain gray nervous mat-
ter in their interior. They are the main points of origin
of the optic nerves, and are connected by commissural fibres
with the optic thalami. In birds, the tubercles are two in
number, instead of four, and are called the tubercula bi-
gemina.
It is probable that the tubercula quadrigemina are in ex-
citable and insensible. "When pain and convulsive move-
ments have apparently followed their mechanical irritation
in living animals, these phenomena have probably been due
to excitation or stimulation of the motor or sensory commis-
sural fibres which pass beneath them. At least, this seems
to be the proper conclusion to draw from the experiments
of Longet.1
As regards the function of the optic lobes, aside from
their action as reflex nervous centres for the movements of
the iris, there is little to be said, except that they preside over
the sense of sight. They are easily reached and operated
upon in birds, where they are very large, and, as Flourens
demonstrated many years ago, their extirpation is followed
by total loss of sight, as well as abolition of the reflex move-
ments of the iris.8 In birds and in those mammals in which
1 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 407.
8 FLOURENS, Sysieme nerveux, Paris, 1842, p. 145.
TUBERCULA QUADEIGEMIXA. 397
they Lave been operated upon, the action in vision is crossed ;
i. e., when the lobe is removed upon one side, the sight is
lost in the opposite eye, vision in the eye upon the same
side being unimpaired. We have long been in the habit, in
class-demonstrations, of removing the optic lobe on one side
from a pigeon, with the result just mentioned. The opera-
tion is quite simple : A part of the skull is removed by the
side of one hemisphere, and the optic lobe is seen, 'in the
form of a large, white tubercle, between the posterior por-
tion of the cerebrum and the cerebellum. A little slit is
then made in its capsule, and the interior is broken up care-
fully with a delicate forceps. The animal generally recovers
from the operation, blinded in the eye upon the opposite
side. In removing the portion of the skull, it is well not to
go too for back, when there is danger of wounding the great
venous sinus and complicating the operation by haemorrhage.
In treating of the special sense of sight, in the next and last
volume, we shall see that the decussation of the optic nerves
is more complex in man than in birds, in which the nerve
from one optic lobe passes totally and exclusively to the eye
upon the opposite side. In man, most of the fibres of the
optic nerve from one side pass to the eye upon the opposite
side ; but a few fibres pass to the eye upon the same side, a
few connect the tubercles upon the two sides, and a few con-
nect the two eyes. It is not known whether or not, in man,
the action of the tubercles in vision is exclusively crossed, as
it appears to be in most of the inferior animals.
The optic lobes undoubtedly serve as the sole centres
presiding over the sense of sight, and not merely as avenues
of communication of this sense to the cerebral hemispheres.
A positive proof of this proposition lies in the fact that the
sense of sight is preserved after complete removal of the
cerebrum, provided that injury of the tubercles have been
carefully avoided.
AVe shall say nothing, in this connection, with regard to
the movements of the iris, except that the reflex action by
398 NEKVOUS SYSTEM.
which the size of the pupil is modified is effected through
the optic lobes as nerve-centres. The mechanism of the
movements of the iris and their regulation through nervous
action are questions of great interest, and are somewhat com-
plex. We have already treated of them to some extent, in
connection with the physiology of the third pair of nerves,
and they will be considered still more fully in the section
on the special sense of sight.
Ganglion of the Tuber Annulare.
The tuber annulare, called the pons Yarolii, or the
mesocephalon, is situated at the base of the brain, just above
the medulla oblongata. It is white externally, and contains
in its interior a large admixture of gray matter. It presents
both transverse and longitudinal white fibres. Its transverse
fibres connect the two halves of the cerebellum. Its longi-
tudinal fibres are connected below, with the anterior pyrami-
dal bodies and the olivary bodies of the medulla oblongata,
the lateral columns of the cord, and a certain portion of the
posterior columns. Above, the fibres are connected with
the crura cerebri, and pass to the brain. The superficial
transverse fibres are wanting in animals in which the cere-
bellum has no lateral lobes.
The general properties of the tuber annulare have been
Demonstrated in the most satisfactory manner by Longet.
In his experiments, direct excitation of the superficial trans-
verse fibres did not produce well-marked convulsive move-
ments, and there were no convulsions when the posterior
fibres were stimulated. When galvanization was applied to
the deeper anterior fibres, convulsive movements were dis-
tinct at each excitation. Stimulation of the posterior portion
always produced pain. This was not constantly observed to
follow irritation of the anterior portion, and, when pain oc-
curred, it was thought to be due to irritation of the root of
the fifth nerve.1
1 LONGET, Traiti de physiologic, Paris, 1869, tome iii., p. 394.
GANGLION OF <THE TUBEE ANNCLAEE. 399
The above experiments, it is true, are not as free iroin
uncertainty as those made upon the more accessible parts of
the eneephalon, but, as far as they go, they tend to show
that the tuber annulare is both insensible and inexcitable in
its superficial anterior portion, which is composed chiefly of
commissural fibres from the cerebellum ; that it is excitable
and probably insensible in its deeper anterior portion, which
seems to be composed chiefly of descending motor conduct-
ors ; and finally, that it is sensible and probably inexcitable
in its posterior portion.
The tuber annulare undoubtedly acts as a conductor of
sensory impressions and motor stimulus to and from the
cerebrum, as we would naturally expect from the direction
of its fibres, and as has been repeatedly shown by cases of
disease, particularly as regards motion. In addition, how-
ever, judging from the fact that it contains numerous nod-
ules of gray matter between fasciculi of white fibres, and
that this gray matter contains cellular elements similar to
those found in other nerve-centres, and from which new
nerve-fibres undoubtedly originate, it would be inferred
that these nodules have a distinct function, and give to the
tuber annulare the properties of a nerve-centre. It will be
interesting, therefore, to follow out the experiments upon
this part, by which its action as a centre has been illustrated.
These experiments are of two kinds : First, the removal of
other encephalic ganglia, leaving only the tuber annulare,
the medulla oblongata, and the cerebellum, and noting the
properties or faculties retained by animals under these con-
ditions. Experiments of this kind are tolerably definite, as
we already know the general functions of most of the other
encephalic ganglia. Second, to note the effects of extirpa-
tioTi of the tuber annulare alone.
If the cerebral hemispheres, the olfactory ganglia, the
optic lobes, the corpora striata, and the optic thalami, be
removed, the animal loses the special senses of smell and
sight and the intellectual faculties, there is a certain amount
128
4:00 NERVOUS SYSTEM.
of enfeeblement of the muscular system, but voluntary mo-
tion and general sensibility are retained. There can be no
doubt upon these points. As far as voluntary motion is
concerned, an animal operated upon in this way is in nearly
the same condition as one simply deprived of the cerebral
hemispheres. There are no voluntary movements which
show any degree of intelligence, but the animal can stand,
and various consecutive movements are executed, which are
entirely different from the simple reflex acts depending
exclusively upon the spinal cord. The coordination of move-
ments is perfect, unless the cerebellum be removed. As re-
gards general sensibility, an animal deprived of all the en-
cephalic ganglia except the tuber annulare and the medulla
oblongata undoubtedly feels pain. This has been demon-
strated in the most conclusive manner by Longet,1 and has
been shown even more satisfactorily by Yulpian.8 In rabbits,
rats, etc., after removal of the cerebrum, corpora striata, and
optic thalami, pinching of the ear or foot is immediately
followed by prolonged and plaintive cries. Both of the
experimenters referred to insist upon the character of these
cries as indicating the actual perception of painful impres-
sions, and as very different from cries that are purely reflex,
according to the ordinary acceptation of this term. Longet
alludes to the voluntary movements and the cries observed
in persons subjected to painful surgical operations, when
incompletely under the influence of an anaesthetic, concern-
ing the character of which there can be no doubt. He re-
gards the movements as voluntary, and the cries as evidence
of the acute perception of pain ; but it is well known that
such patients have no recollection of any painful impression,
though they have apparently experienced great suffering.
As far as we can judge from what we positively know of the
function^ of the encephalic centres, the pain under these
circumstances is perceived by some nerve-centre, probably
1 LONGET, Trai/e de physiologic, Paris, 1869, tome iii., p. 396.
2 VULPIAN, Systeme nerveux, Paris, 1866, p. 542, et seq.
GANGLION OF THE TUBER ANNULARE. 401
the tuber annulare, but the impression is not conveyed to
the cerebrum, and is not recorded by the memory.
Taking all the experimental facts into consideration, the
following seems to be the most reasonable view with regard
to the function of the tuber annulare as a nerve-centre.
It is an organ capable of originating a stimulus giving
rise to voluntary movements, when the cerebrum, corpora
striata, and the optic thalami, have been removed, and prob-
ably regulates the automatic voluntary movements of station
and progression. Many voluntary movements, the result of
intellectual effort, are made in obedience to a stimulus trans-
mitted from the cerebrum, through conducting fibres in the
tuber annulare, to the motor conductors of the cord and the
general motor nerves.
The tuber annulare is also capable of perceiving painful
impressions, which, when all of the encephalic ganglia are
preserved, are also conducted to and are perceived by the
cerebrum, and are remembered ; but there are distinct evi-
dences of the perception of pain, even when the cerebrum
has been removed.
Cases of disease or injury of the tuber annulare on one
side in the human subject show that its action is crossed.
It is a curious fact that lesions of the encephalon involving
the pons may be located during life by the existence of what
is known as alternate paralysis ; i. e., there is hemiplegia on
the side opposite to the brain-lesion, attended with paralysis
of the facial on the same side as the lesion, so that the fa-
cial palsy and the hemiplegia are on opposite sides of the
body. We have already cited, in connection with the physi-
ology of the facial nerve, the cases collected by Gubler, of
this alternate paralysis, in illustration of the decussation of
the deep fibres of origin of the facial ; for when the lesion
involves parts of the encephalon anterior to or above the
pons, the facial paralysis is on the same side as the hemi-
plegia.1 Additional cases of alternate paralysis have been
1 See page 147.
4:02 NERVOUS SYSTEM.
reported by Brown-Sequard, in' an elaborate memoir on the
physiology and pathology of the protuberance.1
Medulla Oblongata.
The chief points of interest in the physiological anatomy
of the medulla oblongata relate to the direction of its fibres,
their connection with the gray matter embedded in its sub-
stance, and the course of the filaments of origin of certain of
the cranial nerves. Concerning the deep origin of the large
root of the fifth, the motor-oculi externus, facial, pneumogas-
tric, spinal accessory, and the sublingual, we shall have noth-
ing to say in this connection, as we have already treated of the
physiological anatomy of these nerves with sufficient minute-
ness ; and we have now to study the functions of the medulla
oblongata, and particularly its action as a nerve-centre.
Physiological Anatomy of the Medulla Oblongata. — The
medulla oblongata is the oblong, enlargement which connects
the spinal cord with the various encephalic ganglia. It is
about an inch and a quarter in length, and nearly an inch
broad, at its widest portion. It rests in the basilar groove
of the occipital bone, extending from the atlas to the lower
border of the tuber annulare, with its broad extremity
above. Like the cord, it has an anterior and a posterior
median fissure.
Apparently continuous with the anterior columns of the
cord, are the two anterior pyramids, one on either side.
Yiewed superficially, the innermost fibres of these pyramids
are seen to decussate in the median line ; but if these
fibres be traced from the cord, it is found that they come
from the white substance of its lateral columns, and that none
of them are derived from the anterior columns. The fibres
of the external portion of the anterior pyramids come from
1 BROWN-SEQUARD, Recherclies sur la physiologic et la pathologic de la protu-
berance annulaire. — Journal de la physiologic, Paris, 1858, tome i., p. 755, etseq. ;
and, Ibid., 1859, tome ii., p. 130, et seq.
MEDULLA OBLONGATA. 403
tlic anterior columns of the cord. At the site of the decus-
sation, the pyramids are composed entirely of white mat-
ter ; but as the fibres spread out to pass to the encephalon
above, they present nodules of gray matter between the
fasciculi.
External to the anterior pyramids, are the corpora oliva-
ria. These are oval, and are surrounded by a distinct
groove. They are white externally, and contain a gray
nucleus, called the corpus dentatum.
External to the corpora olivaria, are the restiform bodies,
formed exclusively of white matter, and constituting the pos-
tero-lateral portion of the medulla. They are continuous
with the posterior columns of the cord. The restiform bod-
ies spread out as they ascend, and pass to the cerebellum,
forming a great portion of the inferior peduncles.
Beneath the olivary bodies, and between the anterior
pyramids and the restiform bodies, are the lateral tracts of
the medulla, called by the French, the intermediary fasciculi.
These are composed of an intimate mixture of white and
gray matter, and have a yellowish-gray color. They receive
all that portion of the antero-lateral columns of the cord
which does not enter into the composition of the anterior
pyramids. These are frequently considered as parts' of. the
restiform bodies, but they are peculiarly interesting, from the
fact that they contain the gray centre presiding over respira-
tion, and for that reason we have described them as distinct
fasciculi.
The posterior pyramids (fasciculi graciles) are the small-
est of all. They pass upward to the cerebrum, without decus-
sating, and are composed exclusively of white matter. As
they pass upward, they diverge, leaving a space at the fourth
ventricle.
The fourth ventricle is in the medulla, and is bounded
above, by the valve of Yieussens and the under surface of the
cerebellum. In the lower part of the floor of the fourth ven-
tricle, are several transverse fasciculi of white matter; but the
4:04 NERVOUS SYSTEM.
greatest part of this portion is composed of a layer of gray
substance.
The two lateral halves of the posterior portion of the me-
dulla are connected together by fibres arising from the gray
matter of the lateral tracts, or intermediary fasciculi, passing
obliquely, in a curved direction from behind forward, to the
raphe in the median line. There are also fibres passing from
before backward, to form a posterior commissure, and fibres
arising from the cells of the olivary bodies, which connect
the gray substance of the lateral halves. Commissural fibres
also connect the gray matter of the lateral tracts with the
corpora dentata of the olivary bodies, and the olivary bodies
with the cerebellum, their fibres forming part of the inferior
peduncle of the cerebellum. In addition, it is probable that
.fibres, taking their origin from all of the gray nodules of
the medulla, pass to the parts of the encephalon situated
above.
As far as the fibres of origin of the nerves are concerned,
it may be stated in general terms that a number of the motor
roots arise from the gray matter of the floor of the fourth
ventricle, the roots of the sensory nerves arising from gray
matter in the posterior portions.
Aside from purely anatomical demonstrations, the con-
nection of the anterior pyramids of the medulla with the cor-
pora striata has been shown by pathological observations.
It is well known that, when the connection between the
nerve-centres and the fibres is destroyed, these fibres after a
time become degenerated. In old lesions of the corpora
striata, Cruveilhier, Tiirk, and, more lately, Yulpian, have
shown that, when the white substance is injured upon one
side, there follow degeneration and atrophy of the fibres of
the corresponding cerebral peduncle and anterior pyramid
of the medulla, and of the lateral portion of the spinal cord
upon the opposite side.1 This important fact illustrates the
connection between the lateral columns of the cord and the
1 VULPIAN, Systeme nervevix, Paris, 1866, p. 470.
MEDULLA OBLONGATA. 405
anterior pyramids of the medulla oblongata, the decussation
of the anterior pyramids, and the passage of fibres from the
anterior pyramids to the corpora striata, in the substance of
the cerebral peduncles.
Functions of the Medulla Oblongata.
It is. hardly necessary to discuss the functions of the me-
dulla oblongata as a conductor of sensory impressions and of
motor stimulus to and from the brain. We know that there
is conduction of this kind from the spinal cord to the ganglia
of the encephalon, and this must take place through the me-
dulla ; a fact which is inevitable, from its anatomical relations,
and which is demonstrated by its section in living animals.
Xor is it necessary to dwell upon its general properties, in
which it resembles the spinal cord, at least as far as has been
demonstrated by experiments upon living animals or upon
animals just killed. It is difficult to expose this part in the
higher classes of animals, but the experiments of Longet *
and of Yulpian 2 show that it is sensitive on its posterior sur-
face and insensible in front. The difficulty of observing the
phenomena which follow its irritation in living animals has
rendered it impossible to determine the limits of its excita-
bility and sensibility as exactly as has been done for the dif-
ferent portions of the cord.
It is also somewhat difficult to determine whether the ac-
tion of the medulla itself, in its relations to motion and sen-
sation, be crossed or direct. As regards conduction from the
brain, the direction is sufficiently well shown by cases of ce-
rebral disease, in which the paralysis, in simple lesions, is
always on the opposite side of the body. Philipeaux and
Yulpian have shown that, in the medulla, this crossed action
is not distinct. After section of one lateral half of the me-
dulla in dogs and Guinea-pigs, there was not complete pa-
1 LOXGET, Traite de physiologic, Paris, 1869, tome ill, p. 377.
2 YrLriAX, System* nerveux, Paris, 1866, p. 484.
4:06 NEJRVOUS SYSTEM.
ralysis of motion, either on one side or the other, though the
animals operated upon were not able to stand.1
The action of the medulla as a reflex nerve-centre depends
upon its gray matter. "When this gray substance is de-
stroyed, certain of the important reflex functions are in-
stantly abolished. From its connections with various of the
cranial nerves, we should expect it to play an important part
in the movements of the face, in deglutition, in the action of
the heart and of various glands, etc., important points which
will be fully considered in their appropriate place. Its
most striking function, however, is in connection with respi-
ration.
Connection of the Medulla Oblongata with Respiration.
• — It did not escape the observation of Galen, that when a
section was made at the summit of the spinal cord, the ani-
mal was suddenly destroyed.2 This fact has been considered
as well established, since the time of Galen, but in 1809, Le-
gallois made a number of experiments upon rabbits, cats,
etc., in which he showed that respiration depends exclu-
sively upon the medulla oblongata and not upon the brain,
and he further located the part which presides over this
function at the site of origin of the pncumogastric nerves : 3
" For, if we open the cranium of a young rabbit, and ex-
tract the brain, by successive portions, from before back-
ward, cutting it by slices, we can remove in this way all of
the brain proper, and then the entire cerebellum and a part
of the medulla oblongata. But it (respiration) ceases sud-
denly when we include in a section the origin of the eighth
pair of nerves (pneumogastrics)." The experiments of Le-
gallois were repeated and confirmed before a commission
from the French Institute, composed of Yon Humboldt,
1 VULPIAN, Systeme ncrveux, Paris, 1866, p. 495
2 GALENUS, De Anatomicis Admtnistrationibus, Liber viii., Cap. ix. — Opera,
Lipsiae, 1821, tomus ii., pp. 696, 697.
3 LEGALLOIS, Experiences sur h prindpe de la vie. — (Euvres, Paris, 1824, tome
i., p. 64. The date of these experiments is given by Legullois on page 74.
MEDULLA OBLONG ATA. 407
Halle, and Percy.1 Flourens, in his elaborate experiments
upon the nerve-centres, extended the observations of Legal-
lois, and limited the respiratory centre in the rabbit, between
the upper border of the roots of the pneumogastrics and a
plane situated about a quarter of an inch below the lowest
point of origin of these nerves ; these limits, of course, vary-
ing with the size of the animal.3 Following these experi-
ments, Longet has shown that the respiratory nervous centre
does not occupy the whole of the medulla included between
the two planes indicated by Flourens, but that it is confined
to the gray matter of the lateral tracts, or the intermediary
fasciculi. This was demonstrated by the fact that respiration
persists in animals after division of the anterior pyramids
and the restiform bodies. Subsequently, Flourens still far-
ther restricted the limits of the respiratory centre, and fully
confirmed the observations of Longet.3
The portion of the medulla oblongata above indicated
presides over the movements of respiration, and is the true
respiratory nerve-centre. Kearly all who have repeated the
experiments of Flourens have found that the spinal cord
may be divided below the medulla oblongata, and that all
of the encephalic ganglia above may be removed, respiratory
movements still persisting. It is a very common thing in
vivisections to kill an animal by breaking up the medulla.
In a dog, for example, we grasp the head firmly with the
left hand, flex it forcibly on the neck, and penetrate with a
stylet a little behind the occipital protuberance, entering be-
tween the atlas and the skull. By a rapid lateral motion of
the instrument, the medulla is broken up, and the animal in-
stantly ceases to breathe. There are no struggles, no mani-
festations of the distress of asphyxia ; the respiratory mus-
1 LEGALLOIS, op. cit., tome i., p. 248.
2 FLOUREXS, Systeme nerveux, Paris, 1842, p. 204.
Flourens was in error when he stated (page 197) that Lorry was the first to
show that animals were instantly killed by destruction of the summit of the
ppinal cord, for this was distinctly indicated by Galen, in the second century.
3 LONGET, Traite de physiologic, Paris, 1869, tome iii., pp. 387, 388.
408 NEKVOUS SYSTEM.
cles simply cease their action, and the animal loses instantly
the sense of want of air. A striking contrast to this is pre-
sented when the trachea is tied or when all of the respiratory
muscles are paralyzed without touching the medulla. The
same phenomena follow injury to the medulla in the human
subject ; and in anaesthesia from the administration of chlo-
roform, a patient wrill sometimes suddenly stop breathing,
apparently because the medulla oblongata becomes affected.
In another volume, we have insisted upon the mechan-
ism of the reflex phenomena of respiration. AYe have con-
clusively shown by experiments, that an impression is re-
ceived by the sensory nerves of the general system, due to
want of oxygen, and not to the irritation produced by carbon-
ic acid ; and that this impression is conveyed to the medulla
oblongata, and gives rise to the reflex movements of respira-
tion. If this impression be abolished, there are no respira-
tory movements ; and if the medulla, the sole centre capable
of receiving this impression and of generating the stimulus
sent to the respiratory muscles, be destroyed, respiration in-
stantly ceases, without any sensation of asphyxia.1
It does not seem that there can be any doubt with regard
to the action of the medulla oblongata as the respiratory
nervous centre ; still, it has been stated by Brown-Sequard,
that the commonly-accepted view is not correct ; that the
sudden arrest of respiratory movements following destruc-
tion of the medulla is due to irritation and not to its re-
moval ; and that, in certain cases, the movements may become
reestablished after the irritation has subsided.2 Schiff noted,
in 1852, that dogs lived for a certain time after injury of
1 See vol. i., Respiration, p. 479, et seq.
Our original experiments on the respiratory sense were made in 1860-'61,
and published in October, 1861. See Experimental Researches on Points con-
nected with the Action of the Heart and with Respiration. — American Journal of
the Medical Sciences, Philadelphia, October, 1861.
2 BROWX-SEQUARD, Recherches snr les causes de mort apres V ablation de la
partie de la moelle allongee qui a ete nommee point vital. — Journal de la physiolo-
gie^ Paris, 1858, tome i., p. 217, et seq. ; and, Recherches experimentales sur la
physiologie de la moelle allongee. — Ibid., 1860, tome iii., p. 151, et seq.
MEDULLA OBLOXGATA. 409
the so-called vital point.1 As regards the experiments upon
which the opinion of Brown-Sequard is based, we have only
to say that, while a return of respiratory movements is per-
haps possible in certain cold-blooded animals (which will live
for weeks after extirpation of the medulla, respiring by the
skin alone) the experiments on rabbits are so extraordinary,
and the results obtained are so diametrically opposed to
those of all other observers, that they cannot be accepted
without full confirmation. As is remarked by Yulpian, if
the cause of arrest of respiration in the higher animals were
due, not to removal of the respiratory centre, but to simple
irritation, these movements should return after the circula-
tion had been kept up for a time by artificial respiration.
This never occurs. " The possibility of reflex movements
remains during all the time of pulmonary insufflation ; but
the respiratory movements are definitively abolished." 3 We
must then adhere to the view that the medulla oblongata is
the centre which presides over the respiratory movements.
To conclude our history of the influence of the medulla
on respiration, we have only to refer to an interesting series
of experiments recently made by Schiff, in which one lateral
half of the cord just below the medulla, or the lowest part
of the medulla, was divided. In these experiments, it was
found that section of the lateral columns at the point of ori-
gin of the first pair of cervical nerves abolished respiratory
movements upon the corresponding side of the body. In
one experiment, the section was made in a dog, and all the
movements, except those of respiration, remained. The ab-
domen was opened, and one-half of the diaphragm was seen
to be entirely passive. In another experiment, exposure of
the diaphragm did not affect the volume of air inspired, but
after section of the lateral column on one side, the volume
of air inspired was diminished by about one-third.3
1 SCHIFF, Lehrbuch der Physiologic, Lahr, 1858-'59, S. 323.
2 VULPIAN, Systeme ncrveux, Paris, 1866, p. 507.
8 SCHIFF, Einfluss des verlangerten Marks auf die Athmung. — Archiv fur die
ytsammte Physiologic, Bonn, 1870, Bd. iiL, S. 624.
ilO NERVOUS SYSTEM.
Vital Point. — Since it has been definitely ascertained
that destruction of a restricted portion of the gray substance
of the medulla produces instantaneous and permanent arrest
of the respiratory movements, Flourens and others have
spoken of this centre as the vital knot, the destruction of
which is immediately followed by death. "With our present
knowledge of the properties and functions of the different
tissues and organs of which the body is composed, it is almost
unnecessary to present any arguments to show the unphilo-
sophic character of such a sweeping proposition. We can
hardly imagine such a thing as instantaneous death of the
entire organism ; still less can it be assumed that any restrict-
ed portion of the nervous system is the one essential, vital
point. Probably a very powerful electric discharge passed
through the entire cerebro-spinal axis produces the nearest
approach to instantaneous death of any thing of which we
have any knowledge ; but, even here, it is by no means cer-
tain that some parts do but for a time retain their so-called
vital properties. In apparent death, the nerves and the
heart may be shown to retain their characteristic proper-
ties ; the muscles will contract under stimulus, and will ap-
propriate oxygen and give off carbonic acid, or respire ; the
glands may be made to secrete, etc. ; and no one can assume
that, under these conditions, the entire organism is dead.
We really know of no such thing as death, except as the vari-
ous tissues and organs which go to make up the entire body
become so altered as to lose their physiological properties be-
yond the possibility of restoration ; and this never occurs for
all parts of the organism in an instant. A person drowned
may be to all appearances dead, and would certainly die with-
out measures for restoration ; yet, in such instances, restora-
tion may be accomplished, the period of apparent death being
simply a blank, as far as the recollection of the individual is
concerned. It is as utterly impossible to determine the ex-
act instant when the vital principle, or whatever it may bo
called, leaves the body in death, as to indicate the time
MEDULLA OBLONGATA. 411
when the organism becomes a living being. Death is noth-
ing more than a permanent destruction of so-called vital
physiological properties ; and this occurs successively, and
at different periods, for different tissues and organs.
When we see that frogs will live for weeks, and some-
times for months, after destruction of the medulla oblongata,
and that, in mammals, by keeping up artificial respiration,
we can prolong many of the most important functions, as
the action of the heart, for hours after decapitation, we can
understand the physiological absurdity of the proposition
that there is any such thing as a vital point, in the medulla,
or in any part of the nervous system.
Connection of the Medulla Oblongata with Various Re-
flex Acts. — There are numerous reflex phenomena that are
completely under the control of the medulla oblongata as a
nerve-centre. Among these are the various acts connected
with respiration, as yawning, coughing, crying, sneezing, etc.
It also presides over the coordination of the muscles con-
cerned in expression, and the act of vomiting. We have seen,
in treating of the pneumogastric nerves, that their galvani-
zation arrests the action of the heart in diastole, the same
result follows galvanization of the medulla at the point of
origin of these nerves.1 In another volume, we have fully
discussed the influence of the medulla upon sugar formation
in the liver, as illustrated by the beautiful experiments of
Bernard, in which he produced diabetes in animals by irri-
tating the floor of the fourth ventricle, and the influence of
this centre upon the quantity and the composition of the
There is very little to be said concerning certain ganglia
and other parts of the brain that we have not yet considered.
The olfactory bulbs, or ganglia, preside over olfaction, and
will be treated of fully in connection with the special senses.
1 See page 225. * See vol. iii., Excretion, pp. 172, 323.
4:12 NERVOUS SYSTEM.
The pineal gland and the pituitary body, in their structure,
present a certain resemblance to the ductless glands, and their
anatomy has been considered in another volume.1 Passing
over the purely theoretical views of Galen, "Willis, Descartes,
and other of the older writers, who had very indefinite ideas
of the functions of any of the encephalic ganglia, we have
only to say that the uses of the pineal gland and pituitary
body in the economy are entirely unknown. The same re-
mark applies to the corpus callosum, the septum lucidum,
the ventricles, hippocampi, and various other minor parts
that are necessarily described in anatomical works. It is
useless to discuss the early or even the recent speculations
with regard to the functions of these parts, which are entirely
unsupported by experimental or pathological facts, and which
have not advanced our positive knowledge. Most of the
parts just enumerated have no physiological history.
Rolling and Turning Movements following Injury of Cer-
tain Parts of the Encephalon.
The remarkable movements of rolling and turning, pro-
duced by section or injury of certain of the commissural
fibres of the encephalon, are not very important in their
bearing upon the functions of the brain, and are rather to be
classed among the curiosities of experimental physiology.
These movements follow unilateral lesions, and are depend-
ent, to a certain extent, upon a consequent inequality in
the power of the muscles on one side, without actual paraly-
sis. Yulpian enumerates the following parts, injury of
which, upon one side, in living animals, may determine
movements of rotation :
" 1. Cerebral hemispheres ;
" 2. Corpora striata ;
" 3. Optic thalami (Flourens, Longet, Schiff) ;
" 4. Cerebral peduncles (Longet) ;
" 5. Pons Yarolii ;
1 See vol. in., Ductless Glands, p. 364.
BOLLING AND .TURNING MOVEMENTS. 413
" 6. Tubercula quadrigemina or bigemina (Flourens) ;
"7. Peduncles of the cerebellum, especially the middle,
and the lateral portions of the cerebellum (Magendie) ;
"8. Olivary bodies, restiform bodies (Magendie) ;
" 9. External part of the anterior pyramids (Magendie) ;
" 10. Portion of the medulla from which the facial nerve
arises (Brown-Sequard) ;
" 11. Optic nerves ;
" 12. Semicircular canals (Flourens) ; auditory nerve
(Br o wn-S equard). ' '
To the parts above enumerated, Vulpian adds the upper
part of the cervical portion of the spinal cord.1
The movements which follow unilateral injury of the
parts mentioned above are of two kinds ; viz., rolling of the
entire body on its longitudinal axis, and turning, always in
one direction, in a small circle, called by the French the
movement of manege. They were first observed in dogs by
Pourfour du Petit, who noted that animals rolled like a ball,
after section of one lateral half of the cerebellum with the
root of one of the peduncles ; 2 but later, Magendie 3 and
Flourens4 noted the same phenomena. In 1823, a curious
case of the same kind of movements in the human subject
was reported by Serres.5 It is not necessary to cite in detail
the numerous experiments of this kind, made by Longet,
Schiff, Brown-Sequard, Yulpian, and others, except as they
have presented explanations, more or less satisfactory, of the
phenomena observed.
A capital point to determine in the phenomena of rolling
or turning is, whether these movements be due to paralysis
1 VULPIAX, Systeme nerveux, Paris, 1866, p. 584.
2 POURFOUR DU PETIT, Nouveau systeme du cerueau. — Recueil d' observations
d'analomie et de chirurgie, Paris, 1766, p. 121.
3 MAGEXDIE, Jfemoire sur les fondions de quelques parties du sysleme nerveux.
— Journal de physiologic, Paris, 1824, tome iv., p. 399, el seq.
4 FLOUREXS, Systeme nerveux, Paris, 1842, p. 489.
5 SERRES, Suite des recherches sur les maladies organiques du cervelet. — Journal
de physiologic, Paris, 1823, tome iii., p. 136.
414: NEKVOUS SYSTEM.
or enfeeblement of certain muscles upon one side of the
body, to a direct or reflex irritation of the parts of the
nervous system involved, or to all of these causes combined.
The experiments of Brown-Sequard and others conclusively
show that the movements may be due to irritation alone, for
they occur when parts of the encephalon and the upper por-
tions of the cord are simply pricked, without section of fibres.1
When there is extensive division of fibres, it is probable that
the effects of the enfeeblement of certain muscles are added to
the phenomena produced by simple irritation. The most
satisfactory explanation of these movements is the one pro-
posed by Brown-Sequard, who attributes them to a more or
less convulsive action of muscles on one side of the body,
produced by irritation of the nerve-centres. He regards the
rolling as simply an exaggeration of the turning movements,
and places both in the same category.3 It is proper to state,
however, that this explanation is not accepted by Longet 3 or
by Vulpian,4 both of whom have made numerous experiments
with regard to the movements of rotation. In addition to
the phenomena just described, Magendie has noted remark-
able movements of the eyes following section of one of
the peduncles of the cerebellum. " The eye of the side op-
erated upon is directed downward and forward : that of the
opposite side is fixed in a direction upward and backward,
which gives to the face a curious expression."5 Longet
noted the same phenomena in dogs and rabbits after division
of one of the restiform bodies.6
1 BROWN-SEQUARD, On Turning and Rolling produced by Injuries of the
Nervous System. — Experimental Researches applied to Physiology and Pathology,
New York, 1853, p. 21.
2 BROWN-SEQUARD, Note sur les mouvements rotatoires. — Journal de la physi-
ologie, Paris, 1860, tome Hi., p. 720.
3 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 397, ft seq.
4 VULPIAN, Systeme nerveux, Paris, 1866, p. 594.
5 MAGENDIE, Lecons sur les fonctions et les maladies du systeme nerveux, Paris,
1841, tome i., p. 261.
6 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 392.
ROLLING AND TURNING MOVEMENTS. - 415
We do not propose to enter into an elaborate discussion of
the above experiments, for the reason that they do not seem
to have advanced our positive knowledge of the functions of
the nerve-centres. In some of them, the movements have
been observed toward the side operated upon, and in others,
toward the sound side. These differences probably depend
upon the fact, that in certain experiments, the fibres are
involved before their decussation, and in others, after they
have crossed in the median line. In some instances, the
movements may be due to a reflex action, from stimulation
of afferent fibres, and in others, the action of the irritation
may be direct. Judging from the fact that most of the en-
cephalic commissural fibres are apparently insensible and
inexcitable under direct stimulation, it is probable that the
action is generally reflex.
Though we have avoided a full discussion of the question
under consideration, it is one that may be, to some, of con-
siderable interest, from the remarkable character of the phe-
nomena observed, and the reader is referred for further in-
formation to the elaborate chapter on this subject by Yulpian 1
and a recent article by Onimus.2 In the latter article, there
are many curious experiments upon frogs and aquatic birds.
In concluding the physiological history of the encephalon,
we have only to refer to the general properties of certain of
the peduncles. Longet found that direct irritation of the
superior and the inferior peduncles of the cerebellum, in
rabbits, produced pain, but the disturbance consequent upon
exposure of the parts did not allow of any accurate observa-
tions upon the movements. He says nothing of the general
properties of the middle peduncles or of the peduncles of the
cerebrum.3
1 VULPIAN, Systeme nerveux, Paris, 1866, p. 583, et seq.
9 ONIMUS, Recherches experimentales sur les phenomenes consecutifs d I 'ablation
du cerveau et sur les mouvements de rotation. — Journal de fanatomie et de la phy-
siologic, Paris, 1870-'7l, tome vii., p. 662.
8 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 398.
127
CHAPTER XY.
SYMPATHETIC NERVOUS SYSTEM.
General arrangement of the sympathetic system — Peculiarities in the intimate
structure of the sympathetic ganglia and nerves — General properties of the
sympathetic ganglia and nerves — Functions of the sympathetic system —
Va so-motor nerves — Reflex phenomena operating through the sympathetic
system — Trophic centres and nerves, so called.
WHILE there are certain points in the physiology of the
sympathetic nervous system that are perfectly well estab-
lished, it must be admitted that its functions are, in many
respects, obscure, and that our positive knowledge of its
general properties and its relations to the functions of nutri-
tion, secretion, movements, etc., amounts to comparatively
little. The very name, sympathetic, is some indication of
our indefinite ideas with regard to its functions ; but we have
adopted this name, for the reason that it is the one most
generally in use, though it has no very exact relation to the
peculiar functions of the system. It is sometimes called the
ganglionic nervous system ; but this name is inappropriate,
as it implies that it alone possesses ganglia. The name of
the system of organic, or vegetative life is more in accord-
ance with its general functions ; but this is not so commonly
used as that of sympathetic system. The older anatomists
and physiologists called the great cord of this system the
nervus intercostalis.
As far as we know, there is no account of the sympathetic
system, even in the most recent works on physiology or in
special treatises, a careful study of which does not convey
SYMPATHETIC NERVOUS SYSTEM. 417
the idea that there is little else in the literature of the sub-
ject than controversial questions of priority, etc., in minor
details, and a few observations, some of them quite unsatis-
factory, with regard to the effects of the division or galvani-
zation of sympathetic filaments upon the functions of circu-
lation, secretion, and animal heat. "We can hardly venture
to hope that this chapter will be exceptional in this regard,
unless we pass over very briefly the bibliographical discus-
sions so elaborately presented by many authors. It is un-
fortunate that well-ascertained facts, which might be stated
in a very few pages, should be so largely overshadowed by a
mass of purely historical details of no great interest. Still,
we must take the physiological data as we find them, and
endeavor not to limit the knowledge to be looked for in
the future, by adopting theories upon insufficient positive
evidence.
There are certain important anatomico-physiological ques-
tions, more or less definitely determined, that have a direct
bearing upon the functions of the sympathetic system. These
are the following : Is the sympathetic anatomically and physi-
ologically dependent upon its connections with the cerebro-
spinal nerves ? What are the general properties of the sym-
pathetic nerves as regards motion and sensation ? Do the
sympathetic ganglia act as independent reflex nerve-centres ?
To what extent and in what way do the sympathetic gan-
glia and nerves influence the functions of the various organs
and tissues to which their filaments are distributed ? A so-
lution of these questions involves a careful and critical study
of the results of experiments on living animals and of patho-
logical facts ; and it is evident that very little information
is to be derived from observations made anterior to the dis-
covery of the properties and functions of the most important
parts of the cerebro-spinal system. We will begin the study
of these points with an account of the general arrangement
and the peculiarities of structure of the sympathetic ganglia
and nerves.
4:18 NERVOUS SYSTEM.
General Arrangement of the Sympathetic System.
Like the cerebro-spinal system, the sympathetic is com-
posed of centres and nerves, at least as far as we can judge
from its anatomy. The centres contain nerve-cells, most of
which differ but little from the cells of the encephalon and
spinal cord. The nerves are composed of fibres, the greater
part of which are identical in structure with the ordinary
motor and sensory fibres. The fibres are connected with
the nerve-cells in the ganglia, and the ganglia are connected
with each other by commissural fibres. These ganglia con-
stitute a continuous double chain, on either side of the body,
beginning above, by the ophthalmic ganglia, and termina-
ting below, in the ganglion impar. It is important to note,
however, that, the chain of sympathetic ganglia is not inde-
pendent, but that each ganglion receives motor and sensory
filaments from the cerebro-spinal nerves, and that some fila-
ments pass from the sympathetic to the cerebro-spinal cen-
tres. The general distribution of the sympathetic filaments
is to mucous membranes, and possibly to integument, to
non-striated muscular fibres, and particularly to the muscu-
lar coat of the arteries. As far as we have been able to
learn from anatomical investigations, there are no fibres de-
rived exclusively from the sympathetic which are distributed
to striated muscles, except those which pass to the muscular
tissue of the heart. Near the terminal filaments of the sym-
pathetic, in most of the parts to which these fibres are dis-
tributed, there exist numerous ganglionic cells.
The general arrangement of the sympathetic ganglia and
the 'distribution of the nerves may be stated, sufficiently for
our purposes, very briefly ; still, a knowledge of certain ana-
tomical points 'is indispensable as an introduction to an in-
telligent study of the physiology of this system.
In the cranium, are four ganglia; the ophthalmic, the
spheno-palatine, the otic, and the submaxillary. In the neck,
are the three cervical ganglia ; the superior, middle, and in-
SYMPATHETIC NERVOUS SYSTEM. 419
ferior. ±n the chest, are the twelve thoracic ganglia, corre-
sponding to the twelve ribs. ' The great semilunar ganglia,
the largest of all, sometimes called the abdominal brain, are
in the abdomen, by the side of the coeliac axis. In the lum-
bar region, in front of the spinal column, are the four, and
sometimes five, lumbar ganglia. In front of the sacrum, are
the four or five sacral, or pelvic ganglia ; and in front of the
coccyx, is a small, single ganglion, the last of the -chain,
called the ganglion impar. Thus, the sympathetic cord, as
it is sometimes called, consists of from twenty-eight to thirty
ganglia on either side, terminating below in a single ganglion.
Cranial Ganglia. — The ophthalmic, lenticular, or ciliary
ganglion is situated deeply in the orbit, is of a reddish color,
and about the size of a pin's-head. It receives a motor
branch from the third pair, and sensory filaments from the
nasal branch of the ophthalmic division of the fifth. It is
also connected with the cavernous plexus and with Meckel's
ganglion. Its so-called motor and sensory roots from the
third and the fifth pair have already been described in con-
nection with these nerves. Its filaments of distribution are
the ten or twelve short ciliary nerves, which pass to the
ciliary muscle and the iris. A very delicate filament from
this ganglion passes to the eye with the central artery of the
retina, in the canal in the centre of the optic nerve.
The functions of the ophthalmic ganglion are connected
exclusively with the action of the ciliary muscle and iris ;
and we will here do nothing more than indicate its anatomi-
cal relations, leaving its physiology to be taken up under the
head of vision.
The spheno-palatine ganglion was first described by
Meckel, and is known as Meckel's ganglion.1 This is the
largest of the cranial ganglia. It is of a triangular shape,
1 MECKEL, De Ganglia secundi Rami quinti Paris Nervorum Cerebri nuper
detecto, Herolini, 1749 ; in LUDWIG, Scriptores Nevrofogici min&res selecti, Lipsiae,
1795, tomus iv., p. 7.
4:20 . NERVOUS SYSTEM.
reddish in color, and is situated in the spheno-maxillary fossa,
near the spheno-palatine foramen. It receives a motor root
from the facial, by the Yidian nerve. Its sensory roots are
the two spheno-palatine branches from the superior maxillary
division of the fifth. Its branches of distribution are quite
numerous. Two or three delicate filaments enter the orbit
and go to its periosteum. Its other branches, which it is
unnecessary to describe fully in detail, are distributed to the
gums, the membrane covering the hard palate, the soft pal-
ate, the uvula, the roof of the mouth, the tonsils, the mucous
membrane of the nose, the middle auditory meatus, a por-
tion of the pharyngeal mucous membrane, and the levator
palati and azygos uvulae muscles. It is probable that the
filaments sent to these two striated muscles are derived from
the facial nerve and do not properly belong to the sympa-
thetic system.1 They were first accurately described, with
their connections, by Longet.2 The ganglion also sends a
short branch, of a reddish-gray color, to the carotid plexus.
The otic ganglion, sometimes called Arnold's ganglion,
is a small, oval, reddish-gray mass, situated just below the
foramen ovale. It receives a motor filament from the facial,
and sensory filaments from branches of the fifth and the
glosso-pharyngeal. Its filaments of distribution go to the mu-
cous membrane of the tympanic cavity and Eustachian tube,
and to the tensor tympani and tensor palati muscles. Reason-
ing from the general mode of distribution of the sympathetic
filaments, those going to the striated muscles are derived
from the facial.3 It also sends branches to the carotid plexus.
The submaxillary ganglion was discovered by Meckel.4
1 In treating of the facial (see page 161), we have shown that the movements
of the levator palati and azygos uvulae are animated by filaments derived from
this nerve, which simply pass through Meckel's ganglion.
2 LONGET, Anatomic et physiologic du systeme nerveux, Paris, 1842, tome ii.,
p. 128.
3 See page 154.
4 MECKEL, De quinto Pare Nervorum Cerebri ; in LUDWIG, Scriptores Nevro-
logici minorcs selecti, Lipsiae, 1791, tomus L, p. 214.
SYMPATHETIC NEKVOTTS SYSTEM. 4:21
It is situated on the submaxillary gland, is small, rounded,
and of a reddish-gray color. It receives motor filaments from
the chorda tympani, and sensory filaments from the lingual
branch of the fifth. Its filaments of distribution go to "Whar-
ton's duct, to the mucous membrane of the mouth, and to
the submaxillary gland.
Cervical Ganglia. — The three cervical ganglia are situ-
ated opposite the third, fifth, and the seventh cervical ver-
tebrae respectively. The middle ganglion is sometimes
wanting, and the inferior is occasionally fused with the first
thoracic ganglion. These ganglia are connected together
by the so-called sympathetic cord. They have numerous
filaments of communication above, with the cranial and the
cervical nerves of the cerebro-spinal system. Branches from
the superior ganglion go to the internal carotid, to form the
carotid and the cavernous plexus, following the vessels as
they branch to their distribution. Branches from this gan-
glion pass to the cranial ganglia. There are also branches
which unite with filaments from the pneumogastric and
the glosso-pharyngeal to form the pharyngeal plexus, and
branches which form a plexus on the external carotid, the
vertebral, and the thyroid artery, following the ramifications
of these vessels.
From the cervical portion of the sympathetic, the three
cardiac nerves arise and pass to the heart, entering into the
formation of the cardiac plexus. The superior cardiac nerve
arises from the superior ganglion ; the middle nerve, the
largest of the three, arises from the middle ganglion, or from
the sympathetic cord, when this ganglion is wanting ; and
the inferior nerve arises from the inferior ganglion or the first
thoracic. These nerves present numerous communications
with various of the adjacent cerebro-spinal nerves, penetrate
the thorax, and form the deep and the superficial cardiac
plexus, and the posterior and the anterior coronary plexus.
In these various plexuses, are found numerous ganglioform
422 NEKVOTJS SYSTEM.
enlargements ; and upon the surface and in the substance
of the heart, are numerous collections of nerve-cells con-
nected with the fibres, which were first accurately described
and figured by Dr. Robert Lee.1
Thoracic Ganglia. — The thoracic ganglia are situated in
the chest, under the pleura, and rest on the heads of the
ribs. They are usually twelve in number, but occasionally
two are fused into one. They are connected together by
the sympathetic cord. They each communicate by two fila-
ments with the cerebro-spinal nerves ; one of these being
white, like the spinal nerves, and probably passing to the
sympathetic, and the other, of a grayish color, is thought to
contain the true sympathetic filaments. From the upper six
ganglia, filaments pass to the aorta and its branches. The
branches which form the posterior pulmonary plexus arise
from the third and fourth ganglia. The great splanchnic
nerve arises mainly from the seventh, eighth, and ninth
ganglia, receiving a few filaments from the upper six gan-
glia. This is a large, white, rounded cord, which penetrates
the diaphragm and passes to the semilunar ganglion, send-
ing a few filaments to the renal plexus and the suprarenal
capsules. The lesser splanchnic nerve arises from the tenth
and eleventh ganglia, passes into the abdomen, and joins the
coeliac plexus. The renal splanchnic nerve arises from the
last thoracic ganglion, and passes to the renal plexus. The
three splanchnic nerves present numerous anastomoses with
each other.
Ganglia in the Abdominal and the Pelvic Cavity. —
The semilunar ganglia on the two sides send off radiating
branches to form the solar plexus. They are situated by
the side of the coeliac axis and near the suprarenal cap-
sules. These are the largest of the sympathetic ganglia.
From these arise numerous plexuses distributed to various
1 LEE, On the Ganglia and Nerves of the Heart. — Philosophical Transactions,
1849, Part i., London, 1849.
SYMPATHETIC NERVOUS SYSTEM. 423
parts in the abdomen, as follows : The phrenic plexus follows
the phrenic artery and its branches, to the diaphragm. The
coeliac plexus subdivides into the gastric, hepatic, and splenic
plexuses, which are distributed to organs as their names in-
dicate. From the solar plexus, different plexuses are given
off, which pass to the kidneys, the suprarenal capsules, the
testes, in the male, and the ovaries, in the female, the intes-
tines, by the superior and the inferior mesenteric plexuses,
the upper part of the rectum, the abdominal aorta, and the
vena cava. The filaments follow the distribution of the
blood-vessels in the solid viscera.
The lumbar ganglia, four in number, are situated in the
lumbar region, upon the bodies of the vertebrae. They are
connected with the ganglia above and below and with each
other by the sympathetic cord, receiving, like the other gan-
glia, filaments from the spinal nerves. Their branches of
distribution form the aortic lumbar plexus and the hypogas-
tric plexus, and follow the course of the blood-vessels.
The four or five sacral ganglia and the ganglion impar
are situated by the inner side of the sacral foramina and in
front of the coccyx. These are connected with the ganglia
above and with each other, and receive filaments from the
sacral nerves, there being generally two branches of com-
munication for each ganglion. The filaments of distribution
go to all of the pelvic viscera and the blood-vessels. The
inferior hypogastric, or pelvic plexus is a continuation of the
hypogastric plexus above, and receives a few filaments from
the sacral ganglia. The most interesting branches from this
plexus are the uterine nerves, which go to the uterus -and
the Fallopian tubes. In the substance of the uterus, the
nerves are connected with small collections of ganglionic
cells, which were described in 1839, by Dr. Robert Lee.1
The sympathetic filaments are undoubtedly prolonged into
the upper and lower extremities, following the course of the
blood-vessels, and are distributed to their muscular coat.
LEE, Memoir on the Ganglia and Nerves of the Uterus, London, 1849.
424: NEKVOTJS SYSTEM.
According to the latest researches, the filaments of the
sympathetic, at or near their termination, are connected with
ganglionic cells, not only in the heart and the uterus, but in
the blood-vessels, lymphatics, anal canals, the submucous and
the muscular layer of the entire alimentary canal, the sali-
vary glands, liver, pancreas, larynx, trachea, pulmonary tis-
sue, bladder, ureters, the entire generative apparatus, supra-
renal capsules, thymus, lachrymal canals, ciliary muscle, and
the iris.1 In these situations, nerve-cells have been demon-
strated by various observers, and it is probable that they
exist everywhere in connection with the terminal filaments
of this system of nerves.
Peculiarities in the Intimate Structure of tJie Sympa-
thetic Ganglia and Nerves. — The peculiarities in the struct-
ure of the cells and fibres of the sympathetic system are
not numerous, nor do they possess very great physiological
importance. The free communications between the sympa-
thetic ganglia and the cerebro-spinal nerves, and the differ-
ences in the general appearance of certain of these anasto-
mosing branches, lead to the important question of their
origin. As a rule, the sympathetic nerves are softer and
more grayish in color than the spinal nerves. When there
are two branches of communication between a ganglion and
a spinal nerve, one of them is white and the other is gray-
ish, and we might infer from this that one, the white, is
derived from the spinal system, and the other, from the sym-
pathetic ; but this is a point not yet settled by microscopical
investigations. It has been conclusively shown, however,
by Courvoisier, that the communicating fibres pass in both
directions. Taking advantage of the degeneration of nerve-
fibres after separation from their proper centres, this ob-
server has demonstrated that, after division of the branches
between the spinal nerves and the sympathetic ganglia, cer-
1 MATER, in STRICKER, Handbuch der Lelire von den Geweben, Leipzig, 1871,
S. 820.
SYMPATHETIC NERVOUG SYSTEM. 425
tain fibres in the end attached to the spinal . nerve become
degenerated, while others retain their anatomical integrity.
This shows that, in all probability, the cells to which the
degenerated fibres belong are in the sympathetic ganglia,
and that the perfect fibres belong to the cerebro-spinal sys-
tem. On the other hand, in the end attached to the sympa-
thetic ganglia, there are degenerated fibres which belong
to the spinal system, and perfect fibres attached to the sym-
pathetic cells. According to these observations, in frogs,
the fibres belonging to the spinal nerves constitute about
two-thirds of the communicating branches, one-third being
derived from the sympathetic system. In rabbits, the pre-
ponderance of the cerebro-spinal fibres is not so great.1
While the branches of the sympathetic contain a large
number of the ordinary medullated fibres, such as are found
in the cerebro-spinal nerves, they also present numerous
fibres of Remalc, and fine fibres, from 10^00 to 6^QO of an
inch in diameter, which are regarded by Kolliker as true
efferent fibres from the sympathetic ganglia.2 "With regard
to the fibres of Reinak, we have nothing to add to what we
have already stated under the head of the general structure
of the nervous system.3 These points, with the fact that
most of the terminal filaments of the sympathetic are con-
nected with nerve-cells in the substance of the different tis-
sues, constitute the most important anatomical peculiarities
of the sympathetic nerve-fibres.
With regard to the cells, which constitute the character-
istic anatomical element of the sympathetic ganglia, we shall
have little to say, as their peculiarities at present seem to be
of purely anatomical interest. They are generally rounded,
ovoid, or pear-shaped, with a nucleus, generally clear, and a
1 COURVOISIER, Beobacldungen tiber den sympathvsclien Qrranzstrang. — Archiv
fur microscopische Anatomic, Bonn, 1866, Bd. ii., S. 30, et seq. The method
adopted in these investigations is the one already referred to, employed by "Wal-
ler. (See page 80.)
8 KOLLIKER, Elements d'histologie humaine, Paris, 1868, p. 426.
3 See page 24.
426 NERVOUS SYSTEM.
distinct nucleolus. They present a nucleated capsule, prob-
ably composed of connective tissue, which is sometimes lined
on its inner surface with a single layer of flattened, polygo-
nal epithelium. Some of the cells are unipolar, some are
bipolar, and some are multipolar. In frogs, Beale and Ar-
nold have described a peculiar appearance in certain cells,
there being a single, straight prolongation, surrounded by a
fine, spiral fibre. These have not been demonstrated in the
human subject, and it is not necessary to enter into a discus-
sion of the probable origin and nature of the spiral fibre.1
The connection between the cells and fibres of the sympa-
thetic is probably the same as in the cerebro-spinal centres,
and is represented in the accompanying diagram, taken from
Leydig.
FIG. 11.
Sympathetic ganglion with multipolar cells ; highly magnified. (LEYDIG, Traite ffhistologie,
Paris, 1866, p. 193.)
General Properties of the Sympathetic Ganglia and Nerves.
The older writers had no definite ideas with regard to the
functions of the sympathetic system, and were divided, even,
on the simple question of its sensibility, some assuming that
1 For a full account of the spiral fibres and the peculiarities of structure of
the sympathetic system, the reader is referred to the elaborate article by Mayer.
(STRICKER, Handbuch der Lehre von den Geweben, Leipzig, 1871, S. 815.)
SYMPATHETIC NERVOUS SYSTEM. 427
the ganglia were absolutely insensible, while others noted
distinct evidences of pain following their irritation in living
animals. Passing to the researches of the more recent ob-
servers, we find that Flourens noted evidences of pain on
pinching the semilunar ganglia, in rabbits.1 Brachet ex-
posed the abdominal and the thoracic ganglia in calves, dogs,
etc., and found them at first insensible, but pricking these
pails produced pain after they had been exposed for a few
minutes. The sensibility thus noted was thought by Brachet
to be due to inflammation following exposure of the gan-
glia.2 Miiller found that mechanical or chemical irritation
of the semilunar ganglia in rabbits produced pain.3 With-
out discussing the observations of Bichat * and others, who
regarded the sympathetic ganglia and nerves as entirely in-
sensible, we will pass to the direct experiments of Longet,
the results of which seem to be entirely trustworthy and
satisfactory, both as regards sensibility and the property of
exciting movements. In all experiments of this kind, it is
of course essential to avoid direct irritation or traction of
the communicating branches from the cerebro-spinal nerves.
In dogs, Longet noted distinct evidences of sensibility fol-
lowing irritation of the semilunar ganglia, and pain after
prolonged stimulation of the ganglia in the cervical and in
the lumbar region, taking all precautions to avoid irritating
the cerebro-spinal filaments. The sensibility of these parts,
however, is dull as compared with that of the ordinary sen-
sory nerves.6 We have also noted a dull but well-marked
sensibility of the cervical ganglia in rabbits. In view of the
decided and uniform results of the most careful recent ex-
periments on this point, there can be no doubt of the exist-
1 FLOUREXS, Recherches experimentales sur lex proprietes d les f emotions du
systeme nerveux, Paris, 1842, p. 230.
2 BRACKET, Recherches experimentales sur les fonctions du systeme ncrveux
yanglionaire, Bruxelles, 1834, p. 305, ei seq.
3 MULLER, Elements of Physiology, London, 1840, vol. L, p. 712.
4 BICHAT, Anatomic generale, Paris, 1801, tome L, p. 227.
5 LOXGET, Traite de phi-siologie, Paris, 1869, tome iii., p, 593.
4:28 NERVOUS SYSTEM.
ence of a certain degree of sensibility in the ganglia of the
sympathetic system.
As regards excitability, recent experiments are quite
satisfactory. Miiller exposed the intestines and the semi-
lunar ganglia in rabbits ; and, having waited until the intes-
tines, which generally present movements on first opening
the abdomen, had ceased their contractions, the peristaltic
movements " were immediately renewed with extraordinary
activity " by touching the ganglia with caustic potash.1 The
experiments of Longet show that a feeble continued galvanic
current applied to the great splanchnic nerves produces con-
tractions of the muscular coat of the intestines, when they
contain alimentary matters, but that no contractions occur
when they are empty.a On the other hand, Pniiger has ob-
served that galvanization of the splanchnic nerves produces
a passive condition of the small intestine ; that is, arrest of
its movements without persistent contractions of its muscu-
lar coat ; but these results were not confirmed in analogous
experiments performed by Biffi.8 More recently, in a series
of very elaborate experiments, by Legros and Onimus, it has
been shown that the induced galvanic current applied to the
splanchnic nerves does not produce peristaltic movements, but
that these movements are excited by the constant current.4
Taking into consideration the most reliable direct obser-
vations upon the sympathetic ganglia and nerves, the fact
that their stimulation induces movements in the non-striated
muscles to which they are distributed can hardly be doubted.
This action is particularly well marked in the muscular coat
of the blood-vessels ; but here, the function of the nerves is
so important, that it merits special consideration, and will
1 MiJLLER, Elements of Physiology, London, 1840, vol. i., p. 713.
2 LONGET, Traite de phyisologie, Paris, 1869, tome iii., p. 595 ; and, Anatomie
ct physiologic du systeme nerveux, Paris, 1842, tome ii., p. 568.
3 PFLUGER ET BIFFI, Sur une systeme qui suspend les mouvemcnts de Pintestin
grele. — Journal de la physiologic, Paris, 1858, tome i., p. 421.
4 LEGROS ET ONIMUS, Recherches experimentales sur les mouvements de Vintestin.
— Journal de I'anatomie, Paris, 1869, tome vi., p. 196.
SYMPATHETIC NERVOUS SYSTEM. 429
be treated of fully under the head of the vaso-motor nerves.
The mechanism of these movements, however, is peculiar.
The action does not immediately follow the stimulation, as
it does in the case of the cerebro-spinal nerves and the striated
muscles, but is induced gradually, beginning a few seconds
after the irritation, endures for a time, and is more or less
tetanic.1 This mode of action is peculiar to the sympathetic
nerves and the non-striated muscular fibres.
"When we remember the invariable connection of the
sympathetic ganglia with the cerebro-spinal nerves, we see
at once the importance of the question of the derivation of
the motor and sensory properties of the ganglionic system.
Are the sympathetic ganglia independent nerve-centres, or do
they derive their properties from the cerebro-spinal system ?
This question may be satisfactorily answered by two kinds
of experimental facts : In the first place, section or irritation
of the spinal cord and certain of the encephalic centres is
capable of influencing the vaso-motor system, a fact which
will be dwelt upon more fully in another connection. In
the second place, the experiments of Bernard upon the sub-
maxillary ganglion and its influence on the secretion of the
submaxillary gland have demonstrated, in the most conclu-
sive manner, that this ganglion is the centre presiding imme-
diately over the reflex phenomena of secretion by the gland ;
but it has also been shown that, when all of the connections
of the submaxillary ganglion with the cerebro-spinal system
are divided, after a few days, this ganglion loses its power as
a reflex nervous centre.8 In the volume on secretion, we
have given numerous examples of reflex action through the
sympathetic system.3 The experiments just cited from Ber-
nard show that individual ganglia belonging to this system
may act independently for a time ; but that this action can-
1 LEGROS ET OXIMUS, De la contraction des muscles de la vie vegetative. —
Journal de V anatomic, Paris, 1869, tome vi., p. 433.
8 BERNARD, RecJierches experimentales sur les nerfs vasculaires et cahrifiques.
—Journal de la physiologic, Paris, 1862, tome v., pp. 407, 410.
8 See vol. iii., Secretion, p. 28, et seq.
430 NERVOUS SYSTEM.
not remain indefinitely, after the cerebro-spinal branches
have been divided. It remains, however, to apply these ex-
periments to other sympathetic ganglia ; but, in the case of
the snbmaxillary, they are very satisfactory, from the facility
with which the parts may be operated upon, and the certainty
with which the ganglion may be separated from its connec-
tions with the cerebro-spinal system. As regards the ex-
planation of the final loss of power over the functions of the
snbmaxillary gland, the experiments of Waller seem to have
escaped the attention of the eminent physiologist whom we
have quoted. There is no experimental fact more conclu-
sively demonstrated than that of the anatomical degeneration
and consequent loss of physiological function of nerve-fibres
in a few days after they have been separated from their cen-
tres of origin. After division of a cerebro-spinal nerve-trunk,
the tubes soon lose their anatomical characters, and will no
longer respond to a galvanic stimulus. In the case of the
fibres operating upon the submaxillary gland, the question
of their degeneration after division of the cerebro-spinal
roots was not submitted to microscopical investigation. If
these fibres had undergone the degeneration which has so
frequently been observed in experiments upon other nerves,
their galvanization would not have produced any effect ;
which was precisely the result obtained by Bernard. In the
absence of direct observations upon this point, it is the most
reasonable view to adopt, that the fibres from the cerebro-
spinal nerves had lost their function, as a natural consequence
of separation from their centres, and that this was the cause
of the absence of effect upon the gland following their gal-
vanization. The observation of Bernard shows, however,
that filaments may pass to special organs from the cerebro-
spinal centres through the sympathetic ganglia.
Functions of the Sympathetic System.
In the earfy part of the last century (1712 and 1725),
Pourfour du Petit demonstrated that the influence of the
FUNCTIONS OF THE SYMPATHETIC SYSTEM. 431
sympathetic nerve in the neck (the great sympathetic was
frequently called the nervus intercostalis) was propagated
from below upward toward the head, and not from the brain
downward. This may be taken as the starting-point of our
definite knowledge of the functions of the sympathetic sys-
tem, though the experiments of Petit only showed the influ-
ence of the cervical portion upon the eye.1 In 1816, Dupuy
removed the superior cervical ganglia in horses, with the
effect of producing injection of the conjunctiva, increase of
temperature in the ear, and an abundant secretion of sweat
upon one side of the head and neck.3 These experiments
showed that the sympathetic has an important influence on
nutrition, calorification, and secretion. In 1851, Bernard
repeated the experiments of Pourfour du Petit, dividing the
sympathetic in the neck on one side in rabbits, and noted,
on the corresponding side of the head and the ear, increased
vascularity, and an elevation in temperature, amounting to
from 7° to 11° Fahr. This condition of increased heat and
vascularity continues for several months after division of the
nerve.3 In 1S52, Brown-Sequard repeated these experiments,
1 PETIT, Memoire dans lequel il est demonlre que les nerfs intercostaux four-
nissent des rameaux qui portent dts esprits dans les yeux. — Memoires de Vacademie
royale des sciences, Annee 1727, Paris, 1729, p. 5, et seq.
2 DUPCY, Versuche iiber die Wegnahme des ersten Halsknolens des Ganglionner-
ven bd Pferden (Aus Leroux's Journ. de Medec., t. xxxvii., 1816, pp 340-350). —
Deutschcs Archiv fur die Physiologic, Halle und Berlin, 1818, Bd. iv., S. 105, et
seq.
We have been unable to consult the article by Dupuy in the original, but the
reference in Meckel's Archiv gives a full account of the experiments and conclu-
sions. In one experiment, it is stated that, after removal of the ganglia on both
sides, in a horse, already feeble and emaciated, the face and ears became hot
and moist. Dupuy does not seem to have attached much importance to the ele-
vation in temperature. In his conclusions, he states that " the consequences
of destruction of the ganglia are, constriction of the pupils, redness of the con-
junctiva, general emaciation, as well as oedema of the extremities and a general
cutaneous eruption. The ganglionic nerve appears to have a great influence
upon nutrition."
3 BERNARD, Influence du grand sympathique sur la sensibilite et sur la calorifi-
cation.— Complex nndus de la societe de biologie, Paris, 1851, tome iii., p. 163.
128
432 NERVOUS SYSTEM.
and attributed the elevation of temperature directly to an
increase in the supply of blood to the parts affected. He
made a most important advance in the history of the sympa-
thetic, by demonstrating that its section paralyzed the mus-
cular walls of the arteries, and, farther, that galvanization
of the nerve in the neck caused the vessels to contract. This
was the discovery of the vaso-motor nerves, concerning which
so much has been written within the past few years, and
it belongs without question to Brown-Sequard, who published
his observations in August, 1852.1 A few months later, in
the same year, Bernard made analogous experiments, and
presented the same explanation of the phenomena observed.3
The above embraces all that is important with regard to
the history of experimental observations upon the sympa-
thetic. It is evident that we could know nothing of the
functions of this system before the time of Pourfour du
Petit, when the prevailing opinion was that the nerve origi-
nated from the encephalon, and that its influence was propa-
gated downward; and the writings of Bichat, Brachet, Tie-
demann, and others, published anterior to the experiments
of Bernard and of Brown-Sequard, present interesting sug-
gestions and theories, but contain little that bears upon our
positive knowledge.
The important points developed by the first experiments
of Bernard and of Brown-Sequard were, that the sympathetic
influences the general process of nutrition, and that many
of its filaments are distributed to the muscular coat of the
blood-vessels. Before these experiments, it had been shown
that filaments from this system influenced the contractions
1 BROWN-SEQUARD, Experimental Researches applied to Physiology and Pathol-
ogy.— The Medical Examiner, Philadelphia, August, 1852, New Series, vol. viii.,
p. 489. In 1839, Valentin referred to filaments of the sympathetic distributed
to the blood-vessels and influencing their calibre {VALENTIN, De Functionibus
Nervorum Cerebralium et Nervi Sympathetici, Bernae, 1839, p. 153, et seq.).
2 BERNARD, Sur les cffets de la section de la portion cephalique du grand sinn-
pathique. — Compte rendu des seances de la societe de biologic pendant le mois de
novembre, Paris, 1852, tome iv., p. 169.
FUNCTIONS OF THE SYMPATHETIC SYSTEM. 433
of the muscular coats of the alimentary canal. Leaving, for
the present, the action of the vaso-motor nerves, we will
briefly recapitulate some of the facts with regard to the in-
fluence of the sympathetic upon animal heat and secretion.
AVhen the sympathetic is divided in the neck, the local
increase in temperature is always attended with a very great
increase in the supply of blood to the side of the head corre-
sponding to the section. The increased temperature is due
to a local exaggeration of the nutritive processes, apparently
dependent directly upon the hypersemia ; and it is not prob-
able that there are any nerves to which the n^me of calorific,
as distinguished from yaso-motor, can justly be applied.
There are numerous instances in pathology of local increase
in temperature attending increased supply of blood to re-
stricted parts.
The experiment of dividing the sympathetic in the neck,
especially in rabbits, is so easily performed, that the phenom-
ena observed by Bernard and Brown- Sequard have been re-
peatedly verified. We have often done this in class-demon-
strations. A very striking experiment is the following, sug-
gested by Bernard : 1 After dividing the sympathetic arid ex-
hibiting the increase in the temperature and the vascularity
of the ear on one side in the rabbit, if both ears be cut off
just above the head with a sharp knife, the artery on the
side on which the sympathetic has been divided will fre-
quently send up a jet of blood to the height of several feet,
while, on the sound side, the jet is always much less forcible,
and may not be observed at all. This experiment succeeds
best in large rabbits.
It is very easy to observe the effects of dividing the
sympathetic in the neck, but analogous phenomena have been
npted in other parts. Among the most striking of these
experiments are those reported by Samuel, who noted an
intense hyperaemia of the mucous membrane of the stomach
1 BERNARD, Rechcrches experimentales sur les nerfs vascidaires et calorifiqucs
du grand sympathique. — Journal de la physiologic, Paris, 1862, tome v., p. 397.
4:34 NERVOUS SYSTEM.
and intestines following extirpation of the coeliac plexus. By
comparative experiments, it was shown that this did not re-
sult from the peritonitis produced by the operation.1
As regards secretion, the influence of the sympathetic is
very marked. When the sympathetic filaments distributed
to a gland are divided, the supply of blood is very much in-
creased, and an abundant flow of the secretion follows. This
point we have already discussed in another volume, and have
referred particularly to the experiments of Bernard upon the
salivary glands.3 In some recent experiments by Peyrani,
it has been shown that the sympathetic has a remarkable in-
fluence over the secretion of urine. "When the nerves are
galvanized in the neck, the amount of urine and urea is in-
creased, and this increase is greater with the induced than
with the constant current. "When the sympathetic is divided,
the quantity of urine and urea sinks to the minimum.3
Since the publication of our volume on secretion, Dr.
Moreau has published a series of observations on the influ-
ence of the sympathetic nerves upon the secretion of liquid
by the intestinal canal, which are peculiarly interesting in
their bearing upon the sudden occurrence of watery diar-
rhoea. In these experiments, the abdomen was opened in a
fasting animal, and three loops of intestine, each from four to
eight inches long, were isolated by two ligatures. All of
the nerves passing to the middle loop were divided, taking
care to avoid the blood-vessels. The intestine was then
replaced, and the wound in the abdomen was closed with
sutures. The next day the animal was killed. The two
loops with the nerves intact were found empty, as is normal
in fasting animals, and the mucous membrane was dry ; but
the loop with the nerves divided was found filled with a
1 SAMUEL, Principes fondamentaux de Vhistoire du systeme ncrveux nutritif.—
Journal de la physiologic, Paris, 1860, tome iii., p. 580.
2 See vol. iii., Secretion, p. 28, et seq.
3 PEYRAXI, Le sympafhique par rapport d la secretion des urines. — Complex
rendus, Paris, 1870, tome Ixf., p. 1300.
FUNCTIONS OF THE SYMPATHETIC SYSTEM. 435
clear, alkaline liquid, colorless or slightly opaline, which pre-
cipitated a few flocculi of organic matter on boiling.1
Vaso-Motor Nerves.
The experiments which we have already cited demonstrate}
beyond a doubt the existence of nerves distributed to the
muscular coats of the blood-vessels, and capable of regulating
their calibre and the quantity of blood sent to different parts.
These are the vaso-motor nerves, discovered by Brown-Se-
quard, in 1S52.2 The importance of nerves capable of regu-
lating what we may call the local circulations is sufficiently
apparent. The glands, for example, require at certain times
an immense increase in their supply of blood, and the same
is probably true of the muscles, brain, and other parts. It
has been shown, by direct experiments upon living animals,
that local variations in the circulation, independent of the
action of the heart, actually take place, and that they are of
great importance in special functions ; and there are nu-
merous instances of such action, which can only take place
through the nervous system. The phenomena of blushing
and pallor, from mental emotions, are familiar examples.
There can be no doubt of the fact that the sympathetic
branches contain filaments capable of modifying the calibre
of the blood-vessels, and that the cerebro-spinal nerves also
contain elements possessing analogous properties ; but when
we reflect upon the extensive anastomoses, in both directions,
between the sympathetic and the ordinary motor and sensory
nerves, we can appreciate the importance of determining the
exact origin and course of these vaso-motor fibres. The first
important question is, whether the vaso-motor filaments be
derived from the sympathetic ganglia or from the cerebro-
spinal centres.
All experiments upon the question just proposed tend to
1 MOREAU, Experiences physioloyiques sur Vintestin. — Bulletin de Tacademie
imp-.riale de medecine, Paris, 1860, tome xxxv., p. 388.
8 See page 432.
4:36 NERVOUS SYSTEM.
show that the vaso-motor nerves are derived exclusively from
the cerebro-spinal system, and do not originate in the sym-
pathetic ganglia. "Without citing the numerous confirmatory
observations of different physiologists, it is sufficient to state
that Schiff has experimentally demonstrated, in the most
conclusive manner, that the vaso-motor nerves are derived
from the cerebro-spinal centres and not from the sympathetic
ganglia.1 There is now no difference of opinion among physi-
ologists upon this point, the only question being the exact
location of the vaso-motor centres. Ludwig and Thiry found
that section of the cord in the upper cervical region produced
dilatation of most of the blood-vessels of the organism, but
notably of the mesenteric vessels, and that galvanization of
the cord at its lower cut extremity caused the vessels to con-
tract.2 These observations have been repeatedly confirmed.
As a summary of our present knowledge of the origin
of the vaso-motor nerves in the cerebro-spinal axis, we may
cite the following remarks, from a review of the experiments
of Schiff, by Brown-Sequard : " 1. That if there are vaso-
motor elements which decussate in the spinal cord, their
number is excessively small. 2. That the facts observed
by M. Schiff, on this subject, admit of a more simple ex-
planation. 3. That a number of the vaso-motor elements
stop in the spinal cord. 4. That a tolerably large number
of vaso-motor elements, coming from different points in the
body, ascend as far as the tuber annulare, and some as far as
the cerebellum and to other parts of the encephalon. 5.
That consequently, the medulla oblongata is not the sole
source of the vaso-motor elements."5 These statements
express pretty much all that we know of the origin of the
vaso-motor elements and their decussation, as far as their
1 SCHIFF, JTntersuchungen zur Physiologic des Nerveiisystems, Frankfurt am
Main, 1855, S. 167, et seq.
2 LUDWIG UNO THIRY, Uber den Einfiuss dcs Halsmarkes a>if den Blntstrom. —
Sitzungs-berichte der mathematischnaturwissemchaftliclien Classe dcr kaiserlichen
tlkademie der Wissenschaften, Wien, Bd. xlix., ii Abtheilung, S. 421, et scq.
3 Journal de la physiologie , Paris, 1858, tome i., p. 214.
FUNCTIONS OF THE SYMPATHETIC SYSTEM. 437
direct action is concerned ; but some important points have
been developed by observations on reflex vaso-motor phenom-
ena, involving a transmission of impressions to the centres
through the nerves of general sensibility.
Reflex Phenomena operating through the Sympathetic
System. — We shall not discuss, in this connection, the reflex
phenomena of secretion, as these have already been consid-
ered with sufficient minuteness in another volume,1 nor
again treat of reflex action, through the sympathetic, upon
the general circulatory system, which has been taken up
fully under the head of the depressor-nerve of the circu-
lation, described by the brothers Cyon,2 but shall here de-
scribe certain reflex acts, involving vaso-motor phenomena,
which we thus far haA^e touched upon very briefly.
In treating of animal heat, the phenomena of which are
intimately connected with the supply of blood to the parts,
we have mentioned the observations of Brown-Sequard and
Lombard, who found that pinching of the skin on one side
was attended with a diminution in the temperature in the
corresponding member of the opposite side, and that some-
times, when the irritation was applied to the upper extremi-
ties, changes were produced in the temperature of the lower
limbs. Tholozan and Brown-Sequard found, also, that low-
ering the temperature of one hand produced a considerable
depression in the heat of the other hand, without any nota-
ble diminution in the general heat of the body. Brown-
Sequard showed that by immersing one foot in water at 41°
Fahr., the temperature of the other foot was diminished
about 7° Fahr. in the course of eight minutes.3 These facts
show that certain impressions made upon the sensory nerves
afiect the animal heat by reflex action. As section of the
sympathetic filaments increases the heat in particular parts,
with an increase in the supply of blood, and their galvaniza-
1 See vol. iii., Secretion, p. 32. 2 See page 229.
3 See vol. iii., Nutrition, p. 416.
438 NERVOUS SYSTEM.
tion reduces the quantity of blood and diminishes the tem-
perature, it is reasonable to infer that the reflex action takes
place through the vaso-motor nerves. If we assume that
the impression is conveyed to the centres by the nerves of
general sensibility, and that the vessels- are modified in
their calibre and the heat is affected through the sympathetic
fibres, we have only to determine the situation of the cen-
tres which receive the impression and generate the stimulus.
These centres, as we have already seen, are not located in
the sympathetic ganglia, but in the cerebro-spinal axis. .
In this connection, we may quote a curious observation
by Schiff, which he brings forward to illustrate the influence
of the brain in certain acts, probably operating through the
sympathetic system : " It is undisputed that psychical acts
are determined by the brain. If we bring a dog and a cat
together, their psychical irritation is manifested more espe
cially therein that the hair of the dog on his back, of the
cat on her tail, stands up. Now, if we destroy, in the cat,
the lumbar portion of the spinal cord, and bring her together
with, a strange dog, the hair of the tail will still rise. If we
leave the spinal nerves intact, the hair of the cat's tail will
remain smooth, even though she be attacked by a dog." l
From all of these observations, and others of the same
kind which we have not thought it necessary to quote, the
existence of vaso-motor nerves and their connection with
centres in the cerebro-spinal axis are sufficiently well estab-
lished. It is certain, also, that centres presiding over par-
ticular functions may be located, as the genito-spinal centre,
in the spinal cord opposite the fourth lumbar vertebra, and
the cilio-spinal centre, in the cervical region of the cord,
both described by Budge.2 A stimulus generated in these
1 SCHIFF, The Independence of the Sympathetic. — Journal of Psychological
Ifcdicine, Xew York, 1871, vol. v., p. 687.
2 BuDfJE, Lehrbuch der specidhn Physiologic dcs Mcnschcn, Leipzig, 1862,
S. 510, 767.
In a recent review of the theory proposed by Cyon ; viz., that the true ^aso-
motor centres are located in the encephalon, above the medulla oblongata and
FUNCTIONS OF THE SYMPATHETIC SYSTEM. 439
centres, sometimes as the result of impressions received
through the nerves of general sensibility, produces contrac-
tion of the non-striated muscular fibres of the iris,1 vasa
deferentia, etc., including the muscular walls of the blood-
vessels. The contraction of the muscular walls of the ves-
sels is tonic ; and when their nerves are divided, relaxation
takes place, and the vessels are dilated by the pressure of
blood. By this action, the local circulations are regulated
in accordance with impressions made on sensory nerves,
the physiological requirements of certain parts, mental emo-
tions, etc. Secretion, the peristaltic movements of the ali-
mentary canal, the movements of the iris, etc., are influenced
in this way. This action is also illustrated in cases of reflex
paralysis, in inflammations as the result of " taking cold,"
and in many pathological conditions, of which it is not our
province to treat. The facts already noted with regard to the
excito-motor action of the spinal cord in the functions of ani-
mal life have their analogy in the vaso-motor reflex system.
When the centres are destroyed, when the sensory nerves
are paralyzed by anaesthetics, or when the true vaso-motor
nerves are divided, reflex vaso-motor action is abolished.
The vaso-motor filaments are not confined to the branches
of the sympathetic, but they exist as well in the ordinary
cerebro-spinal nerves. Bernard has demonstrated this fact
in the most conclusive manner. He divided the fourth,
fifth, sixth, seventh, and eighth pairs of lumbar nj/ves on
one side in a dog, at the spinal column, and paralyzed mo-
the cerebellum, and that no effects upon the blood-vessels following irritation
of the sensory nerves are observed when the encephalon is extirpated, leaving
the medulla and cerebellum, or when the sensory nerves are paralyzed by anaes-
thetics, Heidenhain presents positive results in opposition to the negative obser-
vations of Cycn, at least as far as the experiments after removal of the superior
parts of the encephalon are concerned. (HEIDENHAIN, Ueber Cyorfs n°.ue Theorle
• raleti Innervation der Gefiissntrven. — Archiv fur die gesammte Physiologic,
Bonn, 1871, Bd. iv., S. 551, et seq.)
1 We assume that dilatation of the iris is produced by the contraction of
radiating fibres. Their existence, however, is denied by some anatomists. We
will discuss this question fully under the head of vision.
440 NERVOUS SYSTEM.
tion and sensation in the leg of that side, but the tempera-
ture of the two sides remained the same. He afterward ex-
posed and divided the sciatic nerve on that side, and then
noted a decided increase of temperature.1 This experiment,
which is only one of a large number, shows conclusively that
the ordinary mixed nerves contain vaso-motor fibres, which
are entirely independent of the nerves of motion and sensa-
tion, a fact which is admitted by all physiologists, and has
frequently been illustrated in cases of disease in the human
subject.
It only remains to show that the phenomena following
section of the sympathetic in animals are illustrated in cer-
tain cases of disease or injury in the human subject. It is
excessively rare to observe traumatic injury confined to the
sympathetic in the neck. A single case, however, apparently
of this kind, has lately been reported by Mitchell. A man
received a gunshot-wound in the neck. Among the phe-
nomena observed a few weeks after, were, contraction of
the pupil on the side of the injury, and, after exercise, flush-
ing of the face upon that side. There was no difference in
the temperature upon the two sides, during repose, but no
thermometric observations were made when half of the face
was flushed by exercise.2 Dr. Bartholow has reported sev-
eral cases of unilateral sweating of the head, two observed
by himself, in several of which there was probably compres-
sion of the sympathetic from aneurism. In those cases in
which the condition of the' eye was observed, the pupil was
found contracted in some and dilated in others. In none
of these cases, were there any accurate thermometric obser-
vations.3 In a series of observations by "Wagner, upon the
head of a woman, eighteen minutes after decapitation, pow-
1 BERNARD, RecJierches experimentales sur les nerfs vasculaires et calorifiques
iu Tjrand sympathtque. — Journal de la physiologic, Paris, 1862, tome v., p. 389.
8 MITCHELL, Injuries of Nerves, Philadelphia, 1872, p. 318.
3 BARTHOLOW, Unilateral Sweating of the Head. — Quarterly Journal of Psycho-
logical Medicine, New York, 1869, vol. Hi., p. 134, et seq.
TROPHIC CENTRES AND XEKVES, SO CALLED. 441
erful galvanization of the sympathetic produced great en-
largement of the pupil.1 In such a case as this, it would not
be possible to make any observations on the influence of the
sympathetic upon the temperature.
Trophic Centres and Nerves, so called.
We have deferred the consideration of the so-called tro-
phic nerves until we had treated of the functions of the
sympathetic system, because the vaso-motor nerves, by their
influence upon the circulation, are evidently connected with
the phenomena of nutrition. It is not necessary to dwell
very minutely upon this point ; but cases of disease, as well
as experiments upon the inferior animals, show that when a
muscle is paralyzed, as a result of the abolition of nervous
influence and consequent disease, it becomes atrophied, its
fibres lose their characteristic structure, and finally become
incapable of contracting under any stimulus. As we have
seen that the cerebro-spinal nerves, in addition to their mo-
tor and sensory fibres, contain vaso-motor elements, it be-
comes a question whether the muscles be supplied with
special nerves, aside from those of motion and sensation
and the vaso-motor nerves, which preside over their nutri-
tion. Such could properly be called trophic nerves. Many
pathologists, relying upon the presence of certain lesions
of cells in the cord, in connection with cases of progressive
muscular atrophy, admit the existence of trophic cells and
nerves. It must be admitted, however, that these views
rest upon pathological facts alone, and have not been de-
monstrated by physiological experiments or observations.
After what we have said, it is evident that proper nutri-
tion of the muscular system depends upon its exercise and
the integrity of its motor nerves. In the second place, the
history of monsters shows that the muscular system may be
1 WAGNER, Note sur qicelques experiences sur la partie cervicale du nerfsympa-
ihique chez une femme decapitee. — Journal de la physiologic, Paris, 1860, tome Ui.,
p. 175.
442 NERVOUS SYSTEM.
developed independently of the cerebro-spinal centres. In
the admirable work of Brachet, on the ganglionic system,
numerous cases of anencephalic * monsters are detailed, taken
from Morgagni, Wepfer, Ruisch, Littre, Lallemand, Boux,
Fauvel, Mery, Saviard, Bouhaud, Schellhase, Heyshan,
Bayle, Lordat, Sain t-Hila ire, and others, in which the mus-
cular system was found more or less perfectly developed.
In some of these, the foetus was delivered at term and lived
for several hours. In the case reported by Bayle, the child
was born with two teeth and lived for seven days. Heyshan
reported a case that lived for six days. When we consider
the great number of cases of this kind on record, a few of
which only are cited by Brachet, it is evident that the cere-
bro-spinal centres are not absolutely necessary to develop-
ment in utero. Some of the cases reported presented spas-
modic movements of certain muscles.2
While it is certain that a foetus may become developed
in iitero, when there is reason to suppose that the cerebro-
spinal influence is wanting and the chief nervous operations
are effected through the ganglionic system, direct experi-
ments upon the sympathetic in animals do not positively
show any influence upon nutrition, except as this system
of nerves affects the supply of blood to the parts. When we
divide a sympathetic nerve, there is an apparent exaggera-
tion of the nutritive processes in. particular parts, and there
may be inflammatory phenomena, but atrophy of muscles is
not observed. Indeed, we only have atrophy of muscles
following division of cerebro-spinal nerves, or, as recently-
1 The term anencephalic is here used in the sense in which it was employed
by Saint-Hilaire, as signifying absence of the encephalon and spinal cord, or
the entire cerebro-spinal axis. It is sometimes applied to cases of absence of
the encephalon, which are more commonly called acephalous.
2 BRACKET, Recherches experimentales sur lesfoncliom du system e nerveux yan-
glionaire, Bruxelles, 1834, p. 103, et seq.
At the time the work of Brachet was written, it presented an admirable
account of the physiology of the sympathetic system ; but it antedates the posi-
tive facts ascertained by Bernard, Brown-Sequard, and other writers, to whom
we have made frequent reference.
TROPHIC CENTRES AND NERVES, SO CALLED. 443
observed cases of disease have shown, after disorganization
of cells belonging to what we recognize as motor centres.
As regards the latter condition, there can be no doubt of
the fact that progressive muscular atrophy is attended with
disorganization of certain of the motor cells of the spinal
cord.
Without fully discussing this subject, which belongs to
pathology, the facts may be briefly stated as follows : We
may have progressive atrophy of certain muscles, which may
be uncomplicated with paralysis, except in so far as there is
weakness of these muscles, due to partial and progressive de-
struction of their contractile elements. The only pathologi-
cal condition in these cases, aside from the changes in the
muscular tissue, is destruction of certain cells in the antero-
latcral portions of the cord, with more or less atrophy of
the corresponding anterior roots. £To one has pretended to
have demonstrated cells in the cord, presenting anatomical
peculiarities by which they may be distinguished from the
ordinary motor or sensory elements, but the fact of the de-
generation of certain cells, others remaining normal, and
this fact alone, has led to the distinction, by certain writers,
of trophic cells ; and, of course, these must be connected
with the muscles by trophic nerves.1
"We shall now study the phenomena of progressive mus-
cular atrophy from a physiological point of view, and see if
they afford any positive evidence of the existence of special
1 Cases of progressive muscular atrophy have recently been studied with
great minuteness, and connected with lesions of certain cells in the cord, by
various authors ; among whom may be mentioned, Hayem (Xote sur vn cas
(tairopliie musculaire progressive avec lesions de la modle. — Archives de physiologic,
Paris, 1869, tome ii., pp. 263, 391); Charcot and Joffroy (Deux can d'atrophie
muzcidaire progressive avec lesions de la substance prise et dcs faiweaux anfero-
lateral de la moefle epinere. — Ibid., pp. 354, 629, 744) ; and Duchenne and Jof-
froy (De Vatrophie aigue et chronique des cellules nerveuses de la moelle et du bulbe
rachidien. — Ibid., 1870, tome iii., p. 499).
For a full account of the disease in question, with its relations to the degen-
eration of nerve-cells, the reader is referred to HAMMOND, Diseases of the Nerrov*
System, New York, 1871 p. 663, et *eq.
4:44 NERVOUS SYSTEM.
cells and nerves presiding over the nutrition of the muscular
system, or whether the phenomena observed cannot be ex-
plained by the partial degeneration of the ordinary motor
cells and nerves.
There can be no doubt of the fact that the cells of the
antero-lateral columns of the spinal cord preside over mo-
tion, and that the stimulus' generated in these cells is con-
veyed to the muscles by the anterior roots of the spinal
nerves. It is a fact, no less definite, that when a muscle or
a part of a muscle is deprived of the motor stimulus by
which it is brought into action, its fibres atrophy, become
altered in structure, and lose their contractility. Starting
with these two well-defined physiological propositions, and
assuming that a few of the ordinary motor cells of the cord
are destroyed — we will not call them trophic cells — what
are the phenomena to be expected as a consequence of such
a lesion ? Reasoning from what we know of the physiology
of the nervous system, we should expect to find the follow-
ing conditions :
The destruction of certain motor nerve-cells would cer-
tainly produce degeneration of the fibres to which they give
origin. This has been observed ; for, in this condition, the
anterior roots arising from the diseased portions of the cord
are atrophied. This occurs when any motor nerves are
separated from their cells of origin, and there is no necessity
of assuming the existence of special trophic cells or nerves.
If a few of the motor cells be affected with disease, and
the degeneration be gradual and progressive, we should
expect progressive and partial paralysis of the muscles to
which their nerves are distributed. This paralysis, confined
to a limited number of fibres of particular muscles or sets
of muscles, would give the idea of progressive weakening
of the muscles, and the phenomena would not be those
observed in complete paralysis, produced by section of the
motor nerves. These are precisely the phenomena observed
in progressive muscular atrophy, preceding the paralysis,
TEOPHIC CENTRES AND NERVES, SO CALLED. 445
which is the final result of the disease, and these do not
involve the action of any special centres or nerves.
As regards the muscular atrophy itself, if the nervous
stimulus be progressively destroyed, the muscular tissue will
necessarily undergo degeneration and atrophy.
AVith the above considerations, we leave the trophic cells
and nerves to the pathologist, and can only admit the exist-
ence of centres and nerves specially and directly influencing
the nutrition of the muscular system, when it has been de-
monstrated that there are lesions of particular structures in
the nervous system, which produce phenomena that cannot
be explained by our knowledge of the action of ordinary
motor and sensory nerves and of the vaso-motor system.1
AVe have thus endeavored to represent what is actually
known concerning the sympathetic system, but it is evident
that we have much to learn with regard to its physiology.
The great sympathetic ganglia may have functions of which
we have no definite idea; and we are better prepared to
advance our knowledge in this direction, by admitting our
ignorance, than by attempting to supply the deficiencies hi
our positive information by theories unsupported by facts.
1 \Ve have discussed the question of the existence of trophic nerves from a
physiological point of view only. In a late review of the subject, by Dr. Hand-
field Jones, the same opinion is expressed, based upon pathological arguments,
as will be seen by the following quotation :
" In conclusion, I may state that my review of the subject leads me to dis-
credit very much the doctrine that there exists a special class of trophic nerves ;
inasmuch as all the phenomena, to explain which their existence might be in-
voked, seem to be fairly explicable by alterations in the condition of those
which have been long familiar to us." (HASDFIELD JONES, Are there Special
Trophi-: Xen-es? — St. George's Hospital. Reports, London, 1868, vol. iii., p. 109.)
CHAPTER XYI.
SLEEP.
General considerations — Condition of the organism during sleep — Dreams — Re-
flex mental phenomena during sleep — Condition of the brain and nervous
system during sleep — Theories of sleep — Anaesthesia and sleep produced
by pressure upon the carotid arteries — Differences between natural sleep,
and stupor and coma — Regeneration of the brain-substance during sleep —
Theory that sleep is due to a want of oxygen — Condition of the various func-
tions of the organism during sleep.
we remember that about one-third of our existence
is passed in sleep, and thai, at this time, voluntary motion,
sensation, the special senses, and various of the functions of
the organism, are greatly modified, the importance of a physi-
ological study of this condition is sufficiently apparent. The
subject of sleep is most appropriately considered in connec-
tion with the nervous system, for the reason that the most
important modifications in function are observed in the
cerebro-spinal axis and nerves. Hepose is as necessary to
the nutrition of the muscular system as proper exercise ; but
repose of the muscles relieves the fatigue due to exercise,
without sleep. It is true that after violent and prolonged
exertion, there is frequently a desire for sleep, but simple
repose will often restore the muscular power. After the
most violent effort, a renewal of muscular vigor is most easily
and completely effecte'd by rest without sleep, a fact familiar
to all who are accustomed to athletic exercises. The glands
engaged in the production of the true secretions need certain
Intervals of repose ; but this does not necessarily involve
SLEEP. 447
fileep. After prolonged and severe mental exertion, how-
ever, or after long-continued muscular effort which involves
an excessive expenditure of the so-called nerve-force, sleep
becomes an imperative necessity. If the nervous system be
not abnormally excited by effort, sleep follows moderate
exertion as a natural consequence, and is the only physi-
ological means of complete restoration ; but the two most
important muscular acts ; viz., those concerned in circulation
and respiration, are never completely arrested, sleeping or
waking, though they undergo certain modifications.
In infancy and youth, when the organism is in process
of development, sleep is more necessary than in adult life or
old age. The infant does little but sleep, eat, and digest.
In adult life, under perfectly physiological conditions, we
require about eight hours of sleep ; some persons need less,
but very few require more. In old age, unless after extraor-
dinary exertion, less sleep is required than in adult life.
Each individual learns by experience how much sleep is
necessary for perfect health, and there is nothing which more
completely incapacitates one for mental or muscular effort,
especially the former, than loss of rest.
Sleeplessness is one of the most important of the predis-
posing causes of certain forms of brain-disease, a fact which
is well recognized by practical physicians. One of the most
refined and exquisite methods of torture is long-continued
deprivation of sleep ; and persons have been known to sleep
when subjected to acutely painful impressions. Severe mus-
cular effort, even, may be continued during sleep. In forced
marches, regiments have been known to sleep while walking ;
men have slept soundly in the saddle ; persons will some-
times sleep during the din of battle ; and other instances
illustrating the imperative demand for sleep after prolonged
vigilance might be cited.1 It is remarkable, also, how noises
1 For a number of curious and interesting examples of sleep under the most
unfavorable circumstances, the reader is referred to the admirable work of Dr
Hammond (Sleep and its Derangements, Philadelphia, 1869, p. 14, et seq.).
129
448 NERVOUS SYSTEM.
to which we have become accustomed will fail to disturb our
natural rest. Those who have been long habituated to the
endless noise of a crowded city frequently find difficulty in
sleeping in the oppressive stillness of the country. "We must
have sleep ; and this demand is so imperious, that we soon
accommodate ourselves to the most unfavorable surrounding
conditions. It is remarkable, also, that prolonged exposure
to intense cold induces excessive somnolence, and if this be
not resisted, the sleep passes into stupor, the power of resist-
ance to cold becomes rapidly diminished, and death is the
inevitable result. Intense heat often produces drowsiness,
but, as is wTell known, is not favorable to natural sleep. We
generally sleep less in summer than in winter, though in
summer, perhaps, we are less capable of protracted mental
and physical exertion.
Sleep is preceded by an indescribable feeling of drowsi-
ness, an indisposition to mental or^physical exertion, and a
general relaxation of the muscular system. It then requires
a decided eifort to keep awake ; and if we yield to the sopo-
rific tendency, the voluntary muscles cease to act, the lids
are closed, we cease to appreciate the ordinary impressions
of sound, and we sometimes pass into a dreamless condition,
in which we lose all knowledge of existence. We say some-
times, because the mind is not generally inactive during
what we may regard as normal sleep. We may have dreams
which are not due, as far as can be ascertained, to impres-
sions from the external world received during sleep. Ideas
in the form of dreams may be generated in the brain from
impressions previously received while awake, or trains of
thought may be gradually extended from the moments im-
mediately preceding sleep into the insensible condition.
During the nine years that we have been almost unremit-
tingly engaged in the preparation of this work, we have
frequently labored during sleep for an entire night — to no
purpose, it is true — upon difficult questions to which we had
devoted a great deal of thought.
DREAMS. 449
There may be, during sleep, mental operations of which
we have no consciousness or recollection, unconscious cere-
bration, as it is called by Carpenter.1 It is well known that
we vividly remember dreams immediately on awakening,
but that the recollection of them rapidly fades away, unless
they be brought to mind by an effort to remember and re-
late them. Whatever be the condition of the mind in sleep,
it* the sleep be normal, there is a condition of repose of the
cerebro-spinal system and an absence of voluntary effort,
which restore the capacity for mental and physical exertion.
The impressionability and the activity of the human mind
are so great, most of the animal functions are so subordinate
to its influence, and we are so subject to unusual mental con-
ditions, that it is difficult to determine with exactness the
phenomena of sleep that are absolutely physiological, and to
separate those that are slightly abnormal. We cannot assert,
for example, that a dreamless sleep, in which our existence
is, as it were, a blank, is the only normal condition of repose
of the system ; nor can we determine what dreams are due
to previous trains of thought, to impressions from the exter-
nal world received during sleep, and are purely physiologi-
cal, and what are due to abnormal nervous influence, disor-
dered digestion, etc. We may assume that an entirely re-
freshing sleep is normal, and that is all.
That reflex ideas originate during sleep, as the result of
external impressions, there can be no doubt ; and we have
already alluded to this point under the head of reflex action.2
The most remarkable experiments upon the production of
dreams of a definite character, by subjecting a person during
sleep to peculiar influences, are those of Maury. The hallu-
cinations produced in this way are called hypnagogic,3 and
1 CARPENTER, Principles of Human Physiology, Philadelphia, 1853, p. 784.
2 See page 300
3 From its derivation, this term is .properly applied only to phenomena ob-
served at the instant when we fall asleep, or when we are imperfectly awakened,
and not to the period of most perfect repose.
450 NERVOUS SYSTEM.
they occur when the subject is not in a condition favorable
to sound sleep. The experiments made by Maury upon him-
self are so curious and interesting, that we quote the most
striking of them in full : 1
FIRST OBSERVATION. — " I was tickled with a feather succes-
sively on the lips and inside of the nostrils. I dreamed that
I was subjected to a horrible punishment, that a mask of
pitch was applied to my face, and then roughly torn off,
• tearing the skin of the lips, the nose, and the face.
SECOND .OBSERVATION. — "A pair of pincers is held at a
little distance from my ear, and rubbed with a steel scissors.
I dreamed that I heard the ringing of bells ; this soon be-
came the tocsin, and I imagined myself in the days of June,
1848.
THIRD OBSERVATION. — " I was caused to inhale Cologne-
water. I dream that I am in a perfumer's shop, and the
idea of perfumes doubtless awakens the idea of the East : 'I
am in Cairo, in the shop of Jean Marie Farina. Many ex-
travagant adventures follow, the connection of which es-
capes me.
FOURTH OBSERVATION. — " I am caused to smell a burning
match. I dream that I am at sea (remark that the wind
was then blowing in through the windows), and that the
Saint-Barbe blew up.
FIFTH OBSERVATION. — " I am slightly pinched on the
nape of the neck. I dream that a blister is applied, which
recalls the recollection of a physician who had treated me
in my infancy.
SIXTH OBSERVATION. — "A piece of hot iron is held to
my face, keeping it far enough removed, so that the sensa-
tion of heat should be slight. I dream of chauffeurs, who
enter houses and force the inmates, by putting their feet
to the fire, to reveal where their money was. The idea of
the chauffeurs immediately suggests that of the Duchess
d'Abrantes, who, I suppose in my dream, has taken me as
1 MAURY, Le sommeil el les reves, Paris, 1865, p. 132, ef seq.
' DEEAMS. 4:51
secretary. I had, indeed, long ago read in the memoirs
of this intelligent woman certain details concerning the
chauffeurs.
SEVENTH OBSERVATION. — "The word parafagaramus is
pronounced in my ear. I hear nothing, and awake, hav-
ing had rather a vague dream. The experiment is repeat-
ed when I am asleep in my bed, and the word maman is
pronounced many times in succession. I dream of different
things, but in this dream I heard the humming of bees.
The same experiment, repeated several days after, when I
was scarcely asleep, was more conclusive. The words Azor,
Castor ', Leonore, were pronounced in my ear ; on awaking,
I recollected that I had heard the last two words, which I
attributed to one of the persons who had conversed with
me in my dream.
" Another experiment of the same kind likewise showed
that the sound of the word, and not the idea attached to it,
had been perceived. The words chandeUe, haridelle, were
pronounced in my ear, many times in succession. I awoke
suddenly of my own accord, saying, (?est die. It was im-
possible for me to recall what idea I attached to this answer.
EIGHTH OBSERVATION. — " A drop of water is allowed to
fall on my forehead, I dream that I am in Italy, that I am
very warm, and that I am drinking the wine of Orviette.
XIXTH OBSERVATION. — " A light, surrounded with a red
paper, is many times in succession passed before my eyes.
I dream of a tempest of lightning, and all the remembrance
of a violent storm which I had encountered in the English
Channel, in going from Morlaix to Havre, is present in my
mind."
As regards dreams due to external impressions, it is a
curious fact, which has been noted by many observers, and
one which accords with the personal experience of all who
have reflected upon the subject, that trains of thought and
imaginary events, which seerA to pass over a long period of
time in our dreams, actually occur in the brain within a
452 NERVOUS SYSTEM.
few seconds. A peison is awakened by a certain impres-
sion, which undoubtedly gives rise to a dream that seems
to occupy hours or days, and yet the period of time between
the impression and the awakening is hardly more than a few
seconds ; and persons will drop asleep for a very few min-
utes, and yet have dreams, with the most elaborate details,
and apparently of great length. It is unnecessary to cite
the numerous accounts of literary compositions of merit, the
working out of difficult mathematical problems in dreams,
etc., some of which are undoubtedly accurate. If it be true,
that the mind is capable of forming consecutive ideas during
sleep, which can hardly be doubted, there is no good reason
why these phenomena should not occur, and the thoughts
should not be remembered and noted, immediately on awak-
ening. In most dreams, however, the mind is hardly in a
normal condition, and the brain generally loses the power
of concentration and of accurate reasoning. We sometimes
commit atrocious crimes in our dreams, without appreciating
their enormity, and are often placed in the most absurd
and impossible conditions, without any idea, at the time, of
their extraordinary and unnatural character. This is a fact
sufficiently familiar to every one, and is one which does not
admit of satisfactory explanation.
We have made no attempt to offer an explanation of the
curious psychological phenomena presented during sleep,
and, indeed, we know little enough of the action of the
mind at any time ; but we have merely given the above as
examples of what we may call reflex mental phenomena.
Somnambulism, general ansesthesia, sleep from hypnotics,
the so-called magnetic sleep, ecstasy, catalepsy, trance, etc.,
are abnormal conditions, which we will only consider in so
far as they resemble natural sleep.
Condition of the Brain and Nervous System during Sleep.
As we have already seen, during sleep, the brain may be
in a condition of absolute repose, at least, as far as we have
THEORIES OF SLEEP. 453
any subjective knowledge of mental operations, or we may
have more or less connected trains of thought. There is,
also, as a rule, absence of voluntary effort, though move-
ments may be made, to relieve discomfort from position or
external irritation, without awakening. The sensory nerves
retain their properties, though the general sensibility is some-
what blunted ; and the same may be said of the special senses
of hearing, smell, and probably of taste. The peculiar dreams,
induced in the case of Maury by red lights, show that the
sense of sight is not entirely lost. There is every reason to be-
lieve, however, that the functions of the sympathetic system
are not disturbed or affected by sleep, if we except the action
of the vaso-motor nerves upon the circulation in the brain.
Two opposite theories have long been in vogue with re-
gard to the immediate cause of sleep. In one, this condition
is attributed to venous congestion and increased pressure of
blood in the brain, and this view probably had its origin in
the fact that cerebral congestion induces stupor or coma.
Stupor and coma, however, are entirely distinct from natu-
ral sleep ; for here, the functions of the brain are suspend-
ed, there is no consciousness, no dreaming, and the con-
dition is manifestly abnormal. In animals rendered coma-
tose by opium, the brain may be exposed and is found
deeply congested with venous blood. The same condition
often obtains in profound anaesthesia from chloroform, but a
state of the brain very nearly resembling normal sleep is
observed in anaesthesia from ether. These facts have been
positively demonstrated by experiments upon living ani-
mals, and have been observed in the human subject, in
cases of injury of the head. When opium is administered
in large doses, the brain is congested during the condition
of stupor or coma, but this congestion is relieved when the
animal passes, as sometimes happens, from the effects of the
agent into a natural sleep.1 In view of these facts, and
others which will be stated hereafter, it is unnecessary to
1 HAMMOND, Sleep and its Derangements,, Philadelphia, 1869, pp. 26, 32.
4:54 NERVOUS SYSTEM.
discuss the theory that sleep is attended with, or is produced
by, congestion of the cerebral vessels.
The idea that the circulation in the brain is diminished
during sleep has long been entertained by cartain physiolo-
gists ; but until within a few years, it has rested chiefly upon
theoretical considerations. We find this view enunciated by
Blumenbach, in the following words : " These remote causes
may induce the proximate cause, which, upon mature con-
sideration, I think probably consists in a diminished or im-
peded flow of oxygenated (arterial) blood to the brain, for
that fluid is of the highest importance, during the waking
state, to the reaction of the sensorium upon the senses and
voluntary motions." This opinion was not entirely theo-
retical, as is seen by the following statement: "Besides
other phenomena which accord with this explanation, one is
very remarkable which I witnessed in a living person, and
has been already noticed — that of the brain sinking when-
ever he was asleep, and swelling again with blood the mo-
ment he awoke." 1
Passing over arguments by the older writers, for and
against this theory of sleep, we come to the researches of
Durham, in 1860, in which it wras clearly demonstrated that
the supply of blood to the brain is always greatly diminished
during sleep. These experiments w^ere made upon dogs.
A piece of the skull, about the size of a shilling, was removed
with a trephine, and a wratch-glass was accurately fitted to
the opening and cemented at the edges with Canada balsam.
"When the animals operated upon in this way were awake,
the vessels of the pia mater were seen moderately distended,
and the circulation was active ; but during perfectly natural
sleep, the brain retracted and became pale. " The contrast
between the appearances of the brain during its period of
functional activity, and during its state of repose or sleep was
most remarkable."2 These observations were confirmed in
1 BLUMENBACH, The Institutions of Physiology, Philadelphia, 1817, pp. 178, 179.
2 DURHAM, The Physiology of Sleep. — Guy's Hospital Report^ Third Series,
London, 1860, voL vi., p. 153, et seq.
THEORIES OF SLEEP. 455
the most satisfactory manner by Prof. Hammond, who, in
1854, noted the changes in the circulation during sleep in a
man who had a large opening in The skull from a railroad-
accident. These observations were made independently of
those of Durham, but were not published until some time
after.1 Prof. Hammond cites numerous observations illus-
trating the diminished circulation in the brain during sleep,
in the human subject, which it is unnecessary to refer to in
detail, and this fact may now be considered as definitively
settled.3 He also devised an instrument for measuring the
extent of the cerebral pressure. This instrument consists of
a brass tube, which is screwed into an opening made in the
skull, and is connected with a small glass tube filled with
colored water. The lower end of the brass tube is covered
with a thin sheet of rubber, which rests on the brain, the
cerebral pressure being marked by the height of the liquid
in the glass tube. In experiments made with this apparatus,
Prof. Hammond fully confirmed the results of his previous
observations.8
The influence of diminished supply of blood to the brain
has been illustrated by compression of both carotid arteries.
In an experiment performed on his own person, Dr. Fleming
produced immediate and profound sleep in this way, and
this result invariably .followed in subsequent trials upon
himself and others.4 We have already alluded to the obser-
vations of "Waller, who produced anaesthesia in patients by
pressure upon both pneumogastric nerves ; but, as we then
remarked, the nerves are so near the carotid arteries that
they could hardly be compressed, in the human subject,
1 HAMMOND, Sleep audits Derangements, Philadelphia, 1869, p. 37, et seq.
'2 An interesting case of exposure of the brain in the human subject i& re-
ported by Dr. Brown (American Journal of the Medical Sciences, New Series,
Philadelphia, 1860, vol. si., p. 400).
3 HAMMOND, op. cit., Appendix.
4 FLEMING, Note on the Induction of Sleep and Anaesthesia by Compression of
the Carotids. — British and Foreign Medico-Chirurgical Review, London, 1855, voL
XV., p. 529.
4:56 NEKVOUS SYSTEM.
without interfering with the current of blood, and such
experiments do not positively show whether the loss of sen-
sibility be due to pressure upon the nerves or upon the ves-
sels.1 An important observation bearing upon this point is
the following, cited by Prof. Hammond : In a lady affected
with cirsoid aneurism of the scalp, both carotids were tied
at different times, one by the late Dr. J. Kearney Rogers,
and the other by Prof. "W. II. Yan Buren. " No peculiar
symptoms were observed in consequence of these operations,
except the supervention of persistent drowsiness, which was
especially well marked after the last operation, and which,
even now, is at times quite troublesome." The last opera-
tion was performed seven years ago.a The bearing of these
facts is sufficiently evident. They all go to show that the
supply of blood to the brain is very much diminished during
natural sleep, and that sleep may be induced by retarding
the cerebral circulation by compressing the vessels of supply.
When the circulation is interfered with by compressing the
veins, congestion is the result, and we have stupor or coma.
If diminished now of blood through the cerebral vessels
be the cause of natural sleep, it becomes important to inquire
how this condition of physiological anaemia is brought about.
It must be, that when the system requires sleep, the vessels
of the brain contract in obedience to a stimulus received
through the sympathetic system of nerves, diminishing the
1 See page 256.
2 HAMMOND, op. cit., p. 42.
Ligation of both carotids, when the patient recovers from the operation, does
not always induce drowsiness, which is probably due to free collateral circulation,
by which, in some cases, the full supply of blood to the brain" is maintained.
In a remarkable case published by Mussey, both carotids were tied for aneu-
rism, one being operated upon about six weeks after the other. In this case, it
is remarked that " at no period subsequently to the operation of tying the
second carotid, with the exception of the faintness and debility which occurred
from the actual loss of blood on the removal of the tumor, has there been a
single symptom of deficiency of blood in the brain." (MUSSET, Case of Aneu-
nsm by Anastomosis, in which both the Primitive Carotid Arteries were tied. —
American Journal of the Medical Sciences, Philadelphia, 1829, vol. v., p. 316.)
THEO&IES OF SLEEP. 457
supply of blood, here, as in other parts, under varied physio-
logical conditions. The vessels of the brain are provided
with vaso-motor nerves, and it is sufficient to have noted
that the arteries are contracted during sleep, the mechanism
of this action being well established by observations upon
other parts of the circulatory system. Contraction of the
vessels of the pia mater has been observed by Kathnagel
and others, though there is some discussion with regard to
its exciting cause.1
It must be acknowledged that we know but little of the
intimate nature of the processes of nutrition of the brain
during its functional activity and in repose ; but there can
be no doubt of the fact that there is more or less cerebral
action at all times when we are awake. Though the mental
processes are much less active during sleep, even at this time,
the operations of the brain are not always suspended. It is
equally well established, that exercise of the brain is attended
with physiological waste of nervous substance, and, like other
parts of the organism, its tissue requires periodic repose to
allow of the regeneration of the substance consumed. Analo-
gies to this are to be found in parts that are more easily
subjected to direct observation. The muscles require repose
after exertion, and the glands, when not actively engaged in
discharging their secretions, present intervals of rest.3 As
regards the glands, during the intervals of repose, the supply
of blood to their tissue is very much diminished. It is prob-
able, also, that the muscles in action receive more blood than
during rest ; but it is mainly when these parts are not active,
and when the supply of blood is smallest, that the processes
of regeneration of tissue seem to be most efficient. As a
rule, the functional activity of parts, while it is attended
1 A. reference to these experiments is to be found in the Journal of Anatomy
and Physiology, Cambridge and London, 1871, vol. v., p. 401.
2 Luys has compared the condition of repose of the brain, with its diminished
supply of blood, to the period of inactivity of the glands (Recherches sur k
systhae nerveux, Paris, 1865, p. 450).
458 NERVOUS SYSTEM.
with an increased supply of blood, is a condition more or
less opposed to the process of repair, the hypersemia being,
apparently, a necessity for the marked and powerful mani-
festations of their peculiar functions. When the parts are
in active function, the blood seems to be required to keep at
the proper standard the so-called irritability of the tissues,
and to increase their power of action under proper stimulus.
Exercise increases the power of regeneration and favors full
development, in the repose which 'follows ; but during
rest, the tissues have time to appropriate new matter, and
this does not seem to involve a large supply of blood. A
muscle is exhausted by prolonged exertion ; and the large
quantity of blood passing through it carries away carbonic
^acid, urea, and other products of disassimilation, which are
all increased in amount, until it gradually iises up its capa-
city for work. Then follows repose ; the supply of blood is
reduced, but, under normal conditions, the tissue repairs the
waste which has been excited by action ; the blood furnishing
nutritive matter and carrying away a comparatively small
amount of effete products.
We may safely assume that processes analogous to those
just described take place in the brain. By absence of vol-
untary effort, we allow the muscles time for rest and for the
repair of physiological waste, and their active function is for
the time suspended. As the activity of the brain involves
consciousness, volition, the generation of thought, and, in
short, the mental condition observed while awake, complete
repose of the brain is characterized by the opposite condi-
tions. It is true that we rest the brain without sleep, by
abstaining from mental effort, by the gratification of certain
of the senses, and by mental distraction of various kinds,
and that the mind may work to some degree during sleep ;
but during the period of complete repose, that condition
which is so necessary to perfect health and full mental vigor,
we lose consciousness, volition, there is no thought, and the
brain, which does not receive blood enough to stimulate it
THEORIES OF SLEEP. 4:59
to action, is simply occupied in the insensible repair of its
substance and is preparing itself for future work. The ex-
haustion of the muscles producas a sense of fatigue of the
muscular system, indisposition to muscular exertion, and a
desire for rest, not necessarily involving drowsiness ; fatigue
of the brain is manifested by indisposition to mental exer-
tion, dulncss of the special senses, and a desire for sleep.
Simple repose will relieve physiological fatigue of muscles ;
and, when a particular set of muscles has been used, the
fatigue disappears when these muscles alone are at rest,
though others be brought into action. Sleep, and sleep
alone, relieves fatigue of the brain. "Wlien the sleep has
continued long enough for the rest of the brain and the re-
pair of its tissue, we awake, prepared for new effort.
AVe have now only to refer to a new theory of sleep,
proposed by Sommer. Taking as a basis the researches of
Pettenkofer and Yoit on respiration, Sommer advances the
idea that, when the brain is active, or while we are awake,
the system appropriates but a small quantity of oxygen in
respiration, and eliminates a relatively large proportion of
carbonic acid ; after a time, the oxygen thus appropriated is
consumed, and the system demands a new supply ; during
sleep, the organism appropriates oxygen largely, and elimi-
nates a relatively small amount of carbonic acid. When
the elimination of carbonic acid at the expense of the oxy-
gen stored up reaches a certain point, the necessity for a
farther supply of oxygen induces sleep ; and when, during
sleep, oxygen has been appropriated in sufficient quantity,
the system awakes, prepared for a new period of activity of
the animal functions.1
By reference to the researches of Pettenkofer and Yoit,
we find that these observers, in experiments on a man con-
fined in a chamber in which the interchanges of gases in
respiration could be estimated, noted, in twenty-four hours,
1 SOMMER, Xeue Theorie des Schlafes.—Zeitschrift fur rationeHe Median,
Dritte Reiho, Leipzig uiid Heidelberg, 1868, Bd. xxxiii., S. 214, et seq.
460 NERVOUS SYSTEM.
that the subject of the observation, awake, but in a condition
of complete repose, appropriated sixty-seven per cent, of
the entire amount of oxygen of the twenty-four hours dur-
ing the night, and thirty-three per cent, during the day,
while he eliminated fifty-eight per cent, of the entire amount
of carbonic acid excreted, during the day, and forty-two per
cent, during the night. When the subject of the experi-
ment worked during the day, by turning a heavy wheel,
the appropriation of oxygen was thirty-one per cent, for the
day, and sixty-nine per cent, for the night ; the elimination
of carbonic acid was sixty-nine per cent, for the day, and
thirty-one per cent, for the night. According to these ob-
servations, the system stores up oxygen at night for use
during the day, at this time eliminating a relatively small
quantity of carbonic acid ; and, during the day, excretes
more carbonic acid than during sleep, appropriating then a
relatively small amount of oxygen.1
This theory of sleep seems to rest upon observations too
restricted to be adopted without reserve. It is stated, in-
deed, that the first experiments of Pettenkofer and Yoit
were not confirmed in other observations made upon the
same person.a It is hardly possible, with our present infor-
1 PETTENKOFER UNO VOIT, Ueber Kohlensdureausscheidung und Sauerstoff-
aufnahme wahrend des Wachens und Schlafens beim Menschen. — Annalen der
Chemie und Pharmacie, Leipzig und Heidelberg, 186*7, Bd. cxli., S. 300, 303.
2 Journal of Anatomy and Physiology, Cambridge and London, 1868, vol. ii.,
p. 181.
The statement alluded to above is to be found in the report on physiology,
by Drs. Rutherford, Gamgee, and Frazer (loc. cit.\ but there is no indication
where the new observations of Pettenkofer and Voit were published. We find
no allusion to any experiments later than those published in 1867 in the Anna-
len dcr Chemie und Pharmacie, in Schmidts Jahrbiicher, from that date to the
present time. In an article by these authors on the excretions, etc., observed
in a patient affected with leucocythemia, it appears that the smallest difference
in the appropriation of oxygen during the day and at night, in a heakhy person,
was fifty-one per cent, for the day, and forty-nine per cent, at night, which is
so slight a variation, that it may practically be disregarded. (PETTENKOFER UND
VOIT, Ueber den Stojfverbrauch bei einem leukdmischsn Manne. — Zeitschrift fur
Biologic, Munchen, 1869, Bd. v., S. 327.)
THEORIES OF SLEEP. 461
mation, to assume that sleep is due simply to want of oxy-
gen, and it is more in accordance with well-established
physiological facts to attribute it to a necessity for the gen-
eral regeneration of the nervous tissue, though into this,
the necessity for oxygen may enter as one element in the
physiological repair.
During sleep, nearly all of the functions, except those
directly under the control of the sympathetic nervous sys-
tem, are diminished in activity. The circulation is slower,
and the pulsations of the heart are less frequent, as well as
the respiratory movements. These points have already been
considered under the heads of circulation and respiration.
AVe have but little positive information with regard to the
relative activity of the processes of digestion, absorption,
and secretion, during sleep. The drowsiness which many
persons experience after a full meal is probably due to a de-
termination of blood to the alimentary canal, and a conse-
quent diminution in the supply to the brain.
INDEX.
Abercrombie, brain of, 348
Agraphia, 358
Alternate paralysis, 147, 401
Amputated members, sensation in, 89
Amylacea, corpora, 59
Andral's ninety-three cases of dis-
ease of the cerebellum, analysis
of, 373
Anelectrotonus, 119
Anencephalic and acephalic foe-
tuses, 442
Aphasia, 350
first case of, on record, 352
cases of, 354
Arachnoid, 259
Arnold's ganglion, 420
Associated movements, 86
Atrophy, progressive muscular, . . 443
Auricular branches of the pneumo-
gastrics (see pneumogastric), . . 216
Axis-cylinder (see nerve-fibre), ... 21
Bcsoin de respirer, 236, 408
Brain (see cerebrum and encepha-
lon), 313
Carotids, tendency to sleep, pro-
duced by compression or ligature
of, 455,456
Catelectrotonus, 119
Cauda equina, 265
Cephalo-rachidian fluid, 261
effects of sudden discharge
or increase of, 263
properties, composition, and
functions of, 264
Cerebellum, physiological anatomy
of, 359
course of the fibres in, 361
130
Cerebellum, general properties of, 362
functions of, 363
extirpation of, in animals, ... 365
pathological facts bearing up-
on the functions of, 372
analysis of Andral's ninety-
three cases of disease of, 373
additional cases of disease of,
in the human subject, 378-386
conclusions with regard to the
functions of, in muscular coor-
dination, 386
connection of, with the gen-
erative functions, 388
movements of the testicles,
vasa deferentia, uterus, Fallo-
pian tubes, etc., produced by
irritation of, 363, 389
comparative size of, in stal-
lions, mares, and geldings, 389
development of, hi the lower
animals, 390
paralysis from disease or in-
jury of, 390
properties of the peduncles
of, , 415
Cerebrate of soda, 59
Cerebration, unconscious, 449
Cerebric acid, 59
Cerebrine, 59
Cerebro-spinal axis, general ar-
rangement of, 257
membranes of, 258
Cerebro-spiual fluid (see cephalo-
rachidian fluid), 261
Cerebrum, supposed regeneration
of, after extirpation, 63, 336
— reflex action of, in dreams,
800,449
464:
INDEX.
Cerebrum, physiological anatomy
of (see encephalon), 321
general properties of, 322
excitability of certain por-
tions of, 323
functions of, 324
extirpation of, in animals,. . . 327
pathological facts bearing up-
on the functions of, 337
effects of haemorrhage in,. . . 337
development of, in idiots, . . . 338
comparative development of,
in the lower animals, 340
development of, in different
races of men, and in different in-
dividuals, 341
comparison of the quality of,
with the quality of muscle, 342
table of weights of the brain
in the Caucasian, negro, etc.,. . . 345
table of weights of the brain
in individuals, 345
location of the faculty of ar-
ticulate language in the anterior
lobes of,. . 350
contraction of vessels of, dur-
ing sleep, 457
physiological repair of, dur-
ing sleep, 458 j
Cervical ganglia of the sympa-
thetic, 421
Cholesterine, 50
Chorda tympani, functions of,. . . 155
influence of, upon the sub-
maxillary secretion, 158
Choroid plexus, 260
Ciliary ganglion, 419
Ciliary nerves, influence of, upon
the iris, 133,419
Cilio-spinal centre, 438
Circulation, influence of the pneu-
' mogastrics upon, 223
influence of the sympathetic
system upon 4§2, 433
Coordination of muscular actions,
probable function of the poste-
rior white columns of the spinal
cord in, 289
effects upon, of injury or re-
moval of the cerebellum, 365
connection of the cerebellum
with...... 386
Cornea, termination of nerves in, 45
Corpora amylacea, 59
Corpora striata, functions of, 393
Corpus callosum, 412
Corpus striatum, effects of lesion
of, 337
Cuvier, brain of, 347
Cyou, depressor-nerve of,... 208, 229
Death, definition of, *. 410
Deglutition, influence of the facial
nerves upon, 'f 162
— - influence of the spinal acces-
sory nerves upon, 175
influence of the sublingual
nerves upon, 182
influence of the superior
laryngeal nerves upon, 218
influence of the oesophageal
branches of the pneumogastrics
upon, 241
Depressor-nerve of the circula-
tion, 208, 229
Diarrhoni, ^influence of the sympa-
thetic system in the production
of,.. 434
Digestion, influence of the pneumo-
gastrics upon, 248
Dreams, reflex action of the cere-
brum in, 300, 449
Dupuytren, brain of, 349
Dura muter, 258
Ear, effects of paralysis of the fa-
cial nerve upon, 155
influence of injury or disease
of the semicircular canals upon
the muscular movements (Me-
niere's disease),. . . . 369 (note), 387
Electricity, excitation of nerves
by, 93, 105
action of, upon the nerves, . . 105
action of direct, or descend-
ing, and of inverse, or ascending
currents, upon the nerves, 106
derived currents, 112
induced muscular contrac-
tion, 112
current of, from the exterior
to the cut surface of a nerve,. . 113
effects of a constant current ,
upon the nervous irritability, . . 114
Electrotonus, 115
Encephalon, general arrangement
of, 313
different ganglia of, 314
weight of, 815
physiological anatomy of, ... 31"
INDEX.
465
Encephalon, ganglia at the base of, 393
Excito-motor action (see reflex ac-
tion), 300
Expression, nerve of (see facial
nerve), 145
influence of the facial nerve
' upon, 165
Eye, effects of division of the fifth
nerve upon, 198
Facial nerve, 145
physiological anatomy of,. . . 145
effects upon the eye, of sec-
tion of fibres of, in the median
line, in the floor of the fourth
ventricle, 147
branches of, 148
• summary of anastomoses and
distribution of, 151
properties and functions of, 154
effects of paralysis of, upon
the ear, 155
functions of the chorda tym-
pani, 155
influence of, upon gustation, 156
typical case of division of, in
the human subject, 157
influence of, upon the sub-
maxillary secretion, 158
influence of, upon the move-
ments of the palate and uvula, . . 159
— — functions of the external
branches of, 162
Facial angle 344 (note)
Fallopian tubes, movements of,
from irritation of cerebellum, . . 363
Falx cerebri and falx cerebelli, . . . 259
Fifth nerve, small root of (nerve
of mastication), 139, 140
physiological anatomy of, ... 140
properties and functions of, . 143
large root of (see trifacial), . 184
Filum terminate of the spinal cord, 265
Fisk, James, Jr., brain of, 348
Fourth ventricle, 360, 403
Galvanism, excitation of nerves by
(see electricity) 93, 105
action of, upon the nerves
(see electricity), 105
Ganglia at the base of the enceph-
alon, 393
Ganglion, ophthalmic, lenticular,
or ciliary, 419
spheno-palatine, or Meckel's, 419
Ganglion, otic, or Arnold's, 420
submaxulary, 420
cervical sympathetic, 421
thoracic sympathetic, 422
semilunar, 422
lumbar and sacral sympa-
thetic, 423
Ganglionic nervous system (see
sympathetic), 416
Gasser, ganglion of, '. . .. 185
Generative functions, connection
of the cerebellum with, 388
Genito-spinal centre, 438
Glands, termination of nerves in,. . 35
Glosso-labial paralysis, 182
Gustation, influence of the facial
nerve upon, 156
Heart, influence of the spinal acces-
sory nerves upon, 176
direct influence of the pneu-
mogastrics upon, 225, 411
influence of galvanization of
the medulla oblongata upon,. . . 411
nerves in the substance of, . . 422
Heat, animal, influence of the sym-
pathetic system upon, 431, 437
Hippocampi, 412
Hypnogogic hallucinations, 449
Hypoglossal nerve (see sublingual
nerve), 178
Idiots, development of the brain in, 338
Intestinal secretions, influence of
the sympathetic system upon, . . 434
Intestines, influence of the pneu-
mogastrics upon, 249
Iris, influence of the motor oculi
communis upon, through the cil-
iary nerves, 131, 133
reflex action of the optic
lobes upon, .".' 398
Irritability, nervous (see nerves),. 91
Krause, terminal bulbs of, 42
Language, location of the nerve-
centre presiding over, 350
Laryngeal nerve, superior (see
pneumogastric), 217
, inferior, or recurrent (see
pneumogastric), 220
Larynx, influence of the recurrent
laryngeal nerves upon, 221
Lecithine, 59
466
IKDEX.
Lenticular ganglion, 419
Ligamentum denticulatum, . ...... 260
Liver, influence of the pneumogas-
trics upon, 242
Mastication, nerve of (see fifth
nerve, small root), 139
Meckel's ganglion, 419
Medulla oblongata, decussation of
the motor conductors in, 283
physiological anatomy of, ... 402
origin of nerves in, 404
functions of, 405
connection of, with respira-
tion, 406
influence of division of one
lateral half of, upon respiration, 409
vital point in, 410
connection of, with various
reflex acts, 411
Meissner, corpuscles of, 39
Meniere's disease (see ear), 387
Mesocephalon (see tuber annulare), 398
Motor oculi communis, 126
physiological anatomy of, ... 127
properties and functions of,. 128
muscles of the eye affected
by paralysis of, 129
influence of, upon the iris, 131, 138
typical case 'of paralysis of,
in the human subject, 134
Motor oculi externus, 136
physiological anatomy of, ... 136
properties and functions of,. 137
Muscular atrophy, progressive, . . . 443
tissue, comparison of the
quality of, with the quality of
brain-substance, 342
termination of the nerves in, 29
involuntary, termination of
the nerves in, 34
Myeline, 21
Myelocytes, 55, 360
Negative variation, 120
Nerve-cells, varieties of, 46
striation of the substance of,
by the action of nitrate of silver, 48
fibrillation of the prolonga-
tions of, 48
connection of, with nerve-
fibres and with each other, 50
Nerve-centres, structure of, 45
accessory anatomical ele-
ments of, , 53
Nerve-centres, connective tissue of, 55
blood-vessels of, 56
perivascular canals of, 56
trophic (see trophic), 441
Nerve force, 97
non-identity of, with elec-
tricity, 98
Nerves, structure of, 18
medullated fibres, 19
axis-cylinder, 21
striation of the axis-cylinder
by the action of nitrate of silver, 22
fibrillation of the axis-cylin-
der, 23
simple, or non-medullated
fibres, 23
gelatinous fibres, or fibres of
Remak, 24, 425
accessory anatomical ele-
ments of, 26
perinevre of, 26
fibrous tissue of, 27
branching and course of, .... 28
termination of, in voluntary
muscles/. 29
terminal plates of, in the
muscles, 32
termination of, in involuntary
muscles, 34
termination of, in the uterus, 35
termination of, in glands, ... 35
sensory, corpuscles of Paciiii,
orofVater, 37
sensory, tactile corpuscles, . . 39
sensory, general mode of ter-
mination of, 44
reunion of fibres of different
properties, 61
motor and sensory, 66
anterior and posterior roots
of the spinal, 67
observations of Walker,
Mayo, Bell, and Magendie, on
the spinal roots of, 68-73
properties of the posterior
spinal roots of, 79
influence of the ganglia of the
posterior spinal roots on the nu-
trition of, 80
properties of the anterior
spinal roots of, 80
recurrent sensibility of the
anterior spinal roots of, 81
mode of action of the motor
filaments of, ; 84
INDEX.
467
Nerves, independent action of the
fibres of, 85
— — mode of action of the sensory
filaments of, 88
— — sensation in members after
amputation, 89
irritability of, 91
excitation of, by galvan-
ism, 93, 105
action of woorara upon,. ... 94
mode of disappearance of the
irritability of the motor filaments
of, 96
mode cf disappearance of the
sensibility of, 96
elevation of temperature in,
during their functional activity, 104
action of electricity upon
(see electricity), 105
galvanic current from the ex-
terior to the cut surface of,. ... 113
spinal, general description of, 122
cranial, anatomical classifica-
tion of> 124
cranial, physiological classifi-
cation of (see different cranial
nerves under their special
names), 125
ciliary, 133, 419
Yidian, 420
cardiac sympathetic, 421
splanchnic, 422
solar plexus, 422
in the substance of the heart, 422
spiral fibres of the sympa-
thetic, 420
vaso-motor (see vaso-motor), 435
trophic (see trophic), 441
Nervous conduction, rapidity of,.. 99
system, general considera-
tions of, 13
divisions of, 15
sympathetic, ganglionic, or
organic (see sympathetic), 416
tissue, anatomical divisions
of, 18
composition of, 56
fatty principles in, 58
regeneration of, 60
Nervus intercostalis, 416 j
Xeurilemma of the spinal cord,. . . 260
Neurine, 57
"Neutral point, 120
Nutrition, effects of division of the
fifth nerve upon, 197
(Esophagus, influence of the pneu-
mogastrics upon, 241
Oleo-phosphoric acid and its com-
pounds, 59
Olivary bodies (see medulla oblon-
gata), 403
Ophthalmic ganglion, 419
Optic lobe?, functions of, 396
extirpation of, , 397
action of, upon the iris, 398
Optic thalami, effects of lesion
of, 337
functions of, 394
Organic system of nerves (see
sympathetic), 41C
Pacini, corpuscles of, 37
Palate, influence of the facial nerve
upon the movements of, 159
Paralysis from disease or injury of
the cerebellum, '. . . 390
alternate, 147, 401
Par vagum nerve (see pneumogas-
tric), 203
Patheticus nerve, 1 34
physiological anatomy of,. . . 135
properties and functions of, . 135
Peduncles of the cerebellum, prop-
erties of, 415
Perinevre, 26
Perivascular canal-system of the
nerve-centres, 261
Pharyngeal branches of the pneu-
mogastrics (see pneumogastric), 217
Phonation, influence of the spinal
accessory nerve upon, 171
influence of the recurrent
laryngeal branches of the pneu-
mogastrics upon, 221
Pia mater, 260
Pineal gland, 412
Pituitary body, 412
Pneumogastric nerve, 203
physiological anatomy of, .... 204
anastomoses of, 205
distribution of, 206
depressor-nerve of the circu-
lation, 208, 231
properties and functions of, . 211
properties of the roots of, . . 212
properties and functions of
the auricular branches of, 216
properties and functions of
the pharyngeal branches of, ... 21 7
properties and functions of
468
INDEX.
the superior laryngeal branches
of, 217
Pneumogastric nerve, influence of
the superior laryngeal branches
of, upon deglutition, 218
properties and functions of
the inferior, or recurrent laryn-
geal branches of, r 220
influence of the ' recurrent
laryngeal branches of, upon pho-
nation, 221
influence of the recurrent
laryngeal branches of, upon the
respiratory movements of the
larynx, 222
cardiac branches of, 223
influence of section of, upon
the circulation, 223
influence of galvanization of,
upon the circulation, 225
direct influence of, upon the
heart, 225
reflex influence of, upon the
circulation, 228
properties and functions of
the pulmonary branches of, .... 233
effects of division of, upon
respiration, 234
effects of galvanization of,
upon respiration, 238
properties and functions of
the cesophageal branches of, ... 241
• properties and functions of
the abdominal branches of, .... 242
influence of, upon the liver, . 242
influence of, upon the stom-
ach, 245
influence of, upon digestion, 248
influence of, upon the intes-
tines, 249
summary of the properties
and functions of, 251
anaesthesia produced by com-
pression of, 256 (note)
Pons Varolii (see tuber annulare), 398
Protagon, 57
Recurrent laryngeal branches of
the pneumogastrics (see pneu-
mogastric), . . •. 220
Recurrent sensibility of the ante-
rior roots of the spinal nerves, 81
Reflex action, definition of, 299
of the brain, in dreams, 300, 449
of the spinal cord, 300
Reflex action, in an: vials poisoned
with strychnine or opium, 310
in decapitated animals, 311
of the sympathetic system,
429,437
Remak, fibres of, 24, 425
Respiration, influence of the pneu-
mogastrics upon, 223
sense of want of air, . . 236, 408
effects of galvanization of the
pneumogastrics upon, 238
connection of the medulla ob-
longata with, 406
influence of dividing one lat-
eral half of the medulla oblon-
gata upon, 409
Rolling and turning movements
following injury of certain parts
of the encephalon, 412
Ruloff, brain of, 348
Secretion, influence of the sympa-
thetic system upon, 434
Semicircular canals (see ear), .... 387
Semilunar ganglia, 422
Sleep, . . '. 446
at different periods of life, . . 447
influence of heat and cold
upon, 448
action of the mind during
(see dreams), 449, 452
condition of general sensibil-
ity and of the special senses in, 453
theories of, 453
due to diminished cerebral
circulation, 454
production of, by compres-
sion of the carotids, 455
tendency to, produced by li-
gature of both carotids, 456
physiological repair of the
brain during, 458
theory that it is due to want
of oxygen, 459
influence of, upon various of
the functions of the organism, 461
Spheno-palatine ganglion, 419
Spinal accessory nerve, 166
physiological anatomy of, . . . 167
properties and functions of, 169
functions of the internal
branch of, .' 170
influence of, upon phonation, 171
extirpation of, in animals, . . 172
influence of, upon deglutition, 175
INDEX.
469
Spinal accessory nerve, influence
of, upon the heart, 176
functions of the external
branch of, 177
Spinal cord, regeneration of, after
partial exsection, 65
physiological anatomy of, ... 264
filum terrainale of, 265
columns of, 266
proportion of white to gray
substance in, 266
central canal of, 266
cornua of the gray substance
of, ...".. 267
direction of the fibres of, ... 268
general properties of, 273
effects of galvanization of the
antero-lateral columns of, . 274, 276
effects of galvanization of
the posterior columns of, . . 275, 276
inexcitability and insensibil-
ity of the gray substance of, 277, 278
excitability and insensibility
of the antero-lateral columns of, 278
limits of the sensibility of the
posterior columns of, 278
action of, as a conductor, . . . 279
. transmission of motor stimu-
lus by, 280
. situation of the motor con-
ductors in different regions of, 281
functions of the lateral col-
umns of, 282
decussation of the motor
conductors of, in the medulla
oblongata, 283
decussation of the motor con-
ductors of, in the cervical region, 283
transmission of sensory im-
pressions in, 285
probable functions of the pos-
terior white columns of, in mus-
cular coordination, 289
decussation of the sensory
conductors of, 290
summary of the action of, as
a conductor, 295
action of, as a nerve-centre, 298
reflex action of (see reflex
action), 300
Stomach, Influence of the pneumo-
gastrics upon, 245
Sublingual nerve, 178
physiological anatomy of, ... 178
ganglion upon the root of,. . 179
Sublingual nerve, properties and
functions of, 180
effects of section of, 182
influence of, upon deglutition, 182
Submaxillary ganglion, 420
influence of, upon the sub-
maxillary gland, 429
Substantia gelatinosa of the spinal
cord, 267
Sympathetic nervous system,-. . . . 416
general arrangement of,. ... 418
cranial ganglia of, 419
cervical ganglia of, 421
cardiac nerves of, 421
thoracic ganglia of, 422
pulmonary plexus of, 422
splanchnic nerves, 422
solar plexus, 422
semilunar ganglia, 422
lumbar and pelvic ganglia of, 423
uterine nerves of, 423
peculiarities in the intimate
structure of, 424
connections of, with cerebro-
spinal nerves, 424
spiral fibres of, 426
sensibility and excitability of, 426
influence of stimulation of
parts of, upon the intestines,. . . 428
influence of, upon the sub-
maxillary gland, 429
reflex action in, 429, 437
functions of, 430.
division of the sympathetic
cord in the neck, 431
influence of, upon animal
heat, secretion of sweat, etc., 431, 437
influence of, upon the circu-
lation, 432,433
influence of, upon secretion, 434
— — influence of, upon the urine, 434
influence of, upon the intes-
tinal secretions, 434
influence of, upon certain
psychical acts, 438
cases of disease or injury of,
in the human subject, 440
experiments upon, in a de-
capitated criminal, 440
Tactile corpuscles, 39
Taste (see gustation), 156
Tentorium, 259
Terminal bulbs of the sensory
nerves, . . ... 42
470
INDEX.
Testicles, movements of, produced
by irritation of the cerebel-
lum, 363, 389
Trifacial nerve, 184
physiological anatomy of, ... 184
Gasserian ganglion of, 1 85
properties and functions of, 189
division of, in the cranial
cavity, 190
immediate effects of division
of, 192
exquisite sensibility of, 193
remote effects of division of, 196
effects of division of, upon
nutrition, 198
paralysis of, in the human
subject, 201
Trochlearis nerve (see patheticus), 134
Trophic centres and nerves, so
called, 441
progressive muscular atro-
phy, 443
Tuber annulare, properties and
functions of, 398
alternate paralysis in lesions
of, 147,401
Tubercula quadrigemina, functions
of, 396
extirpation of, 397
action of, upon the iris, .... 398
Urine, influence of the sympa-
thetic system upon, 434
Uterus, movements of, produced by
irritation of the cerebellum, 363, 389
Uterus, nerves of, 423
Uvula, influence of the facial nerve
upon the movements of 162
Vagus nerve (see pneumogastric), 203
Vasa deferentia, movements of,
produced by irritation of the
cerebellum, 363
Vaso-motor nerves, 435
derivation of, from the cere-
bro-spinal centres, 436, 440
Vater, corpuscles of, 37
Velum interpositum, 260
Ventricle, fourth, 360, 403
Ventricles of the brain, 412
Vertigo, in cases of disease of the
cerebellum and of disease of the
semicircular canals, 387
Vidian nerve, 420
Vital #oint in the medulla oblon-
gata, 410
Voice, influence of the spinal ac-
cessory nerve upon (see phona-
tion),.. 171
influence of the recurrent
laryngeal nerves upon (see pho-
nation), 221
Wagner, corpuscles of, 39
Webster, brain of, 348
Woorara, action of, upon the
nerves, 94
Wrisberg, nerve of. 145, 156
ganglion upon th,e root of,. . 148
CATALOGUE
OP
MEDICAL WORKS
ANSTIE.
Neuralgia, and Diseases which resemble it.
By FRANCIS E. AXSTIE, M. D., F. R. C. P.,
Senior Assistant Physician to Westminster Hospital : Lecturer on Materia Medica in West'
minster Hospital School : and Physician to the Belgrave Hospital for Children : Editor
of "The Practitioner" (London), etc.
1 vol., 12mo. Cloth, $2.50.
"It is a valuable contribution to scientific medicine."— The Lancet (London).
"His work upon Neuralgia is one of the most interesting, instructive, and practical,
we have seen for a long time. We have given it careful reading and thoughtful study,
and, for a treatise of its size, we are free to sav that we have never met one that gives
more practical information and is fuller of useful suggestions." — Medical Record.
BARKER.
On Sea-sickness.
By FORDYCE BARKER, M. D.,
Clinical Professor of Midwifery and the Diseases of Women in the Bellevue Hospital
Medical College, etc.
1 vol., 16mo. 36 pp. Flexible Cloth, 75 cents.
Reprinted from the NEW YORK MEDICAL, JOTTRNAL. By reason of the great demand
for the number of that journal containing the paper, it is now presented in book form,
with such prescriptions added as the author has found useful in relieving the suffering
from sea-sickness.
BARNES.
Obstetric Operations, including the Treatment
of Haemorrhage.
By ROBERT BARNES, M. D., F. R. C. P., LOXDOX,
Obstetric Physician to and Lecturer on Midwifery and the Diseases of Women and Chil-
dren at St. Thomas's Hospital; Examiner on Midwifery to the Royal College of Phy-
sicians and to the Royal College of Surgeons; formerly Obstetric Physician to the
London Hospital, and late Physician to the Eastern Division of the Royal Maternity
Charity.
WITH ADDITIONS, by BENJAMIN F. DAWSON, M. D.,
Late Lecturer on Uterine Pathology in the Medical Department of the University of New
York : Assistant to the Clinical Professor of Diseases of Children in the College of
Physicians and Surgeon?, New York : Physician for the Diseases of Children to the
New York Dispensary : Member of the >>ew York Obstetrical Society, of the Medical
Society of the County of New York, etc., etc.
Second American Edition. 1 vol., 8vo. 503 pp. Cloth, $4.50.
To the student and practitioner this work will prove of the greatest value, being, as it
is, a most perfect text-book on " Obstetric Operations," by one who has fairly earned the
right to assume the position of a teacher.
"Snch a work as Dr. Barnes's was greatly needed. It is calculated to elevate the
practice of the obstetric art in this country, and to be of great service to the practitioner."
— Lancet.
D. Appleton & Co?s Medical Publications.
Bellevue and Charity Hospital Reports.
The volume of Bellovue and Charity Hospital Reports
for 1870, containing valuable contributions from
ISAAC E. TAYLOR, M. D., WILLIAM A. HAMMOND, M. D.,
AUSTIN FLINT, M. D., T. GAILLARD THOMAS, M. D.,
LEWIS A. SAYRE, M. D., FRANK H. HAMILTON, M. D.,
and others.
1 vol., 8vo. Cloth, $4.00.
" These institutions are the most important, as regards accommodations for
patients and variety of cases treated, of any on this continent, and are surpassed
by but few in the world. The gentlemen connected with them are acknowledged
to be among the first in their profession, and the volume is an important addition
to the professional literature of this country." — Psychological Journal.
BENNET
Winter and Spring on the Shores of
the Mediterranean j or, the Rimer a, Mentone, Italy,
Corsica, Sicily, Algeria, Spain, and Biarritz, as Win-
ter Climates.
By J. HENRY BENNET, M. D.,
Member of the Royal College of Physicians, London; late Physician-Accoucher to the
Royal Free Hospital; Doctor of Medicine of the University of Paris; formerly Resi-
dent Physician to the Paris Hospitals (ex-Interne des Hopitaux de Paris), etc.
This work embodies the experience of ten winters and springs passed by Dr. Bennet
on the shores of the Mediterranean, and contains much valuable information for physi-
cians in relation to the health- restoring climate of the regions described.
1 vol., 12mo. 621 pp, Cloth, $3.50.
11 Exceedingly readable, apart from its special purposes, and well illustrated.1'— Even-
ing Commercial.
"It has a more substantial value for the physician, perhaps, than for any other class or
profession. . . . We commend this book to our readers as a volume presenting two
capital qualifications— it is at once entertaining and instructive.' — N. Y. Medical Journal.
On the Treatment of Pulmonary Con-
sumption, by Hygiene, Climate,' and Medicine, in its
Connection with Modern Doctrines.
By JAMES HENRY BENNET, M. D.,
Member of the Royal College of Physicians, London; Doctor of Medicine of the University
of Paris, etc., etc.
1 vol., thin 8vo. Cloth, $1.50.
An interesting and instructive work, written in the strong, clear, and lucid manner
which appears in all the contributions of Dr. Bennet to medical or general literature.
"We cordially commend this book to the attention of all, for its practical common-
sense views of the nature and treatment of the scourge of all temperate climates, pulmo-
nary consumption."— Detroit Review of Medicine.
D. Appleton & CoSs Medical Publications.
BILLROTH.
General Surgical Pathology and The-
rapeuticS) in Fifty Lectures. A Text-book for Students
and Physicians.
By Dr. THEODOR BILLROTH,
Professor of Surgery in Vienna.
Translated from the Fourth German Edition, with the special permission
of the Author, by
CHARLES E. HACKLEY, A. M., M. D.,
Surgeon to the New York Eye and Ear Infirmary ; Physician to the New York Hospital ; Fellow
of the New York Academy of Medicine, etc.
1 vol., 8vo. 676 pp., and 152 Woodcuts. Cloth, $5.00.
Professor Theodor Billroth, one of the most noted authorities on
Surgical Pathology, gives in this volume a complete resume of the exist-
ing state of knowledge in this branch of medical science. The fact of
this publication going through four editions in Germany^ and having
been translated into French, Italian, Russian, and Hungarian, should be
some guarantee for its standing.
SPECniEI OF rLLTJBTBATIONS.
Mammary Cancer, acinons form, magnified 60 diameters.
" The want of a book in the English language, presenting in a concise form the
views of the German pathologists, has long been felt ; and we venture to say no
book could more perfectly supply that want than the present volume
We would strongly recommend it to all who take any interest in the progress of
thought and observation in surgical pathology and surgery." — The Lancet.
"A great addition to our literature." — N. Y. Mecical Journal,
"We can assure our readers that they will consider neither money wasted in
ite purchase, nor time hi its perusal." — The Medical Investigator.
D. Appleton & (70. 's Medical Publications.
COMBE.
The Management of Infancy, Physiologi-
cal and Moral. Intended chiefly for the Use of
Parents.
By ANDREW COMBE, M. D.
REVISED AND EDITED
By SIR JAMES CLARK, K. 0. B., M. D., F. R. S.,
Physician-in-ordinary to the Queen.
First American from the Tenth London Edition. 1 vol., 12mo. 302 pp.
Cloth, $1.50.
" In the following pages I have addressed myself chiefly to parents
and to the yonnger members of the medical profession ; but it is not to
them alone that the subject ought to prove attractive. The study of in-
fancy, considered even as an element in the history and philosophy of
man, abounds in interest, and is fertile in truths of the highest practical
value and importance." — Extract from Author's Preface.
" This excellent little book should be in the hand of every mother of a family ;
and if some of our lady friends would master its contents, and either bring up
their children by the light of its teachings, or communicate the truths it contains
to the poor by whom they are surrounded, we are convinced that they would ef-
fect infinitely more good than by the distribution of any number of tracts what-
ever .... We consider this work to be one of the few popular medical treatises
that any practitioner may recommend to his patients ; and, though, if its precepts
are followed, he will probably lose a few guineas, he will not begrudge them if
he sees his friends' children grow up healthy, active, strong, and both mentally
and physically capable." — The Lancet.
DAVIS.
Conservative Surgery, as exhibited in remedying
some of the Mechanical Causes that operate injuri-
ously loth in Health and Disease. With Illustrations.
By HE^RY G. DAVIS, M. D.,
Member of the American Medical Association, etc., etc.
1 vol., 8vo. 315 pp. Cloth, $3.00.
The Author has enjoyed rare facilities for the study and treatment
of certain classes of disease, and the records here presented to the pro-
fession are the gradual accumulation of over thirty years' investigation.
" Dr. Davis, bringing, as he does to his specialty, a great aptitude for the
solution of mechanical problems, takes a high rank as an orthopedic surgeon,
and his very practical contribution to the literature of the subject is both valu-
able and opportune. We deem it worthy of a place in every physician's library.
The style is unpretending, but trenchant, graphic, and, best of all, quite intelli-
gible."— Medical Record.
D. Appleton & Co?s Medical Publications.
FLINT.
The Physiology of Man. Designed to rep-
resent the Existing State of Physiological Science as
applied to the Functions of the Human Body,
By AUSTIN FLINT, JE., M. D.,
Professor of Physiology and Microscopy in the Bellevue Hospital Medical College, and in the
Long Island" College Hospital; Fellow of the New York Academy of Medicine ; Microscopist
to Bellevue Hospital
In Five Volumes. 8vo. Tinted Paper.
Yolume I. — The Blood ; Circulation; Respiration.
8vo. 502 pp. Cloth, $4.50.
SPECIMEN OF ILLtTSTBATIONS.
Ducts and Acini of the Mammary Organs.
" If the remaining portions of this work are compiled with the same care and
accuracy, the whole may vie with any of those that have of late years been pro-
duced in our own or in foreign languages." — British and foreign Medico-Chirurgi-
cal Review.
" As a book of general information it will be found useful to the practitioner,
and, as a book of reference, invaluable in the hands of the anatomist and physi-
ologist."— Dublin Quarterly Journal of Medical Science.
" The complete work will prove a valuable addition to our systematic treatises
on human physiology." — The Lancet.
" To those who desire to get in one volume a concise and clear, and at the
same time sufficiently full resume of ' the existing state of physiological science,'
we can heartily recommend Dr. Flint's work. Moreover, as a work of typographi-
cal art it deserves a prominent place upon our library-shelves. Messrs. Appleton
& Co. deserve the thanks of the profession for the very handsome style in which
they issue medical works. They give us hope of a time when it will be very
generally believed by publishers that physicians' eyes are worth saving." — Medi-
cal Gazette.
D. Appleton & CoSs Medical Publications.
Flint's Physiology. Volume II.— Alimenta-
tion; Digestion; Absorption; Lymph and Chyle.
8vo. 556 pp. Cloth, $4.50.
" The second instalment of this work fulfils all the expectations raised by the
perusal of the first. . . . The author's explanations and deductions bear
evidence of much careful reflection and study. . . . The entire work is one
of rare interest. The author's style is as clear and concise as his method is
studious, careful, and elaborate." — Philadelphia Inquirer.
" We regard the two treatises already issued as the very best on human physi-
ology which the English or any other language affords, and we recommend them
with thorough confidence to students, practitioners, and laymen, as models of
literary and scientific ability." — N. Y. Medical Journal.
" We have found the style easy, lucid, and at the same time terse. The prac-
tical and positive results of physiological investigation are succinctly stated,
without, it would seem, extended discussion of disputed points." — Boston Medical
and Surgical Journal.
" It is a volume which will be welcome to the advanced student, and as a
work of reference." — The Lancet.
" The leading subjects treated of are presented in distinct parts, each of which
is designed to be an exhaustive essay on that to which it refers." — Western Jour-
nal of Medicine.
Volume III. — Secretion ; Excretion ; Ductless Glands ; Nu-
trition ; Animal Heat ; Movements ; Voice and Speech.
8vo. 526 pp. Cloth, $4.50.
" Dr. Flint's reputation is sufficient to give a character to the book among the
profession, where it will chiefly circulate, and many of the facts given have been
verified by the author in his laboratory and in public demonstrations." — Chicago
Courier.
" The author bestows judicious care and labor. Facts are selected with dis-
crimination, theories critically examined, and conclusions enunciated with com-
mendable clearness and precision." — American Journal of the Medical Sciences.
" The work is calculated to attract other than professional readers, and is
written with sufficient clearness and freedom from technical pedantry to be per-
fectly intelligible to any well-informed man." — London Saturday Review.
" From the extent of the author's investigations into the best theory and prac-
tice of the present day, the world over, and the candor and good judgment which
he brings to bear upon the discussion of each subject, we are justified in regarding
his treatises as standard and authoritative, so far as in this disputed subject
authority is admissible. — New York Times.
Volume IV. — The Nervous System.
This volume is now ready. It is a work of great interest, and, in
conjunction with the " Treatise on Diseases of the Nervous System," by
Dr. Wm. A. Hammond, constitutes a complete work on " The Physiology
and Pathology of the Nervous System."
Volume V. — Generation. (In press.)
1J. Appleton & CoSs Medical Publications.
FLINT.
Manual of Chemical Examination of
the Urine in Disease. With Brief Directions for tJie
Examination of the most Common Varieties of Uri-
nary Calculi.
By AUSTIN FLINT, JR., M. D.,
Professor of Physiology and Microscopy in the Bellevue Hospital Medical College ; Fellow of the
New York Academy of Medicine; Member of the Medical Society of the County of New
York ; Resident Member of the Lyceum of Natural History in the City of New York, etc.
Third Edition, revised and corrected. 1 vol., 12mo. 77 pp. Cloth, $1.00.
The chief aim of this little work is to enable the busy practitioner to
make for himself, rapidly and easily, all ordinary examinations of Urine;
to give him the benefit of the author's experience in eliminating little
difficulties in the manipulations, and in reducing processes of analysis
to the utmost simplicity that is consistent with accuracy.
" We do not know of any work in English so complete and handy as the
Manual now offered to the profession by Dr. Flint, and the high scientific reputa-
tion of the author is a sufficient guarantee of the accuracy of all the directions
given." — Journal-of Applied Cliemistry.
" We can unhesitatingly recommend this Manual." — Psychological Journal.
"Eminently practical." — Detroit Review of Medicine.
On the Physiological Effects of Severe
and Protracted Muscular Exercise. With Special Ref-
erence to its Influence upon the Excretion of Nitrogen.
By AUSTIN FLINT, JR., M.D.,
Professor of Physiology in the Bellevue Hospital Medical College, New York, etc., etc.
1 vol., 8vo. 91 pp. Cloth, $2.00.
This monograph on the relations of Urea to Exercise is the result of
a thorough and careful investigation made in the case of Mr. Edward
Payson Weston, the celebrated pedestrian. The chemical analyses were
made under the direction of R. O. Doremus, M. D., Professor of Chem-
istry and Toxicology in the Bellevue Hospital Medical College, by
Mr. Oscar Loew, his assistant. The observations were made with the
cooperation of J. C. Dalton, M. D., Professor of Physiology in the Col-
lege of Physicians and Surgeons ; Alexander B. Mott, M. D., Professor
of Surgical Anatomy; W. H. Van Buren, M. D., Professor of Principles
of Surgery ; Austin Flint, M. D., Professor of the Principles and Prac-
tice of Medicine; W. A. Hammond, M. D., Professor of Diseases of the
Mind and Nervous System — all of the Bellevue Hospital Medical College.
" This work will be found interesting to every physician. A number of im-
portant results were obtained valuable to the physiologist." — Gin. Med. Repertory.
D. Appleton & CoSs Medical Publications.
HAMMOND.
A Treatise on Diseases of the Nervous
System.
By WILLIAM A. HAMMOND, M. D.,
Professor of Diseases of the Mind and Nervous System, and of Clinical Medicine, in the Bellevue
Hospital Medical College ; Physician-in-Chief to the New York State Hospital for Diseases
of the Nervous System, etc., etc.
SECOND EDITION, REVISED AND CORRECTED.
With Forty-five Illustrations. 1 vol., 8vo. 750 pp. Cloth, $5.00.
The treatise embraces an introductory chapter, which relates to the
instruments and apparatus employed in the diagnosis and treatment of
diseases of the nervous system, and five sections. Of these, the first
treats of diseases of the brain ; the second, diseases of the spinal cord ;
the third, cerebro-spinal diseases ; the fourth, diseases of nerve-cells ;
and the fifth, diseases of the peripheral nerves. One feature which may
be claimed for the work is, that it rests, to a great extent, upon the per-
sonal observation and experience of the author, and is therefore no mere
compilation.
" The author's clear and terse style of diction renders the book exceedingly
readable, and the cases reported and cited add much to the interest of the text.
. . . There is so much that is entertaining in the mental and other manifesta-
tions of nervous disorder, especially when presented as they are here, that a work
of this kind will find many readers outside the profession ; and, it may be hoped,
will serve not only to interest and amuse, but to induce a closer observance of
those hygienic laws upon whose violation many of the ailments here treated of
depend." — New York Medical Journal.
" The work is replete with useful knowledge, and every physician who expects
to be called on, as an expert, to testify in cases of supposed insanity, after the
commission of crimes, should give the book a thorough perusal." — Leavenworth
Medical Herald.
" That a treatise by Prof. Hammond would be one of a high order was what
we anticipated, and it affords us pleasure to state that our anticipations have
been realized." — Cincinnati Medical Repertory.
" It affords a vast amount of information, is captivating, and worth reading."
— Cincinnati Lancet and Observer.
" This is unquestionably the most complete treatise on the diseases to which
it is devoted that has yet appeared in the English language ; and its value is
much increased by the fact that Dr. Hammond has mainly based it on his own
experience and practice, which, we need hardly remind our readers, have been
very extensive." — London Medical Times and Gazette.
" Free from useless verbiage and obscurity, it is evidently the work of a
man who knows what he is writing about, and knows how to write about it." —
Chicago Medical Journal.
D. Applet on & Co?s Medical Publications.
HOLLAND.
Recollections of Past Life,
By SIR HENRY HOLLAXD, Bart., M. D., F. R. SM K. C. B., etc.,
President of the Royal Institution of Great Britain, Physician-in-Ordinary to the Queen,
etc., etc.
1 vol., 12mo, 351 pp. Price, Cloth, $2.00.
A very entertaining and instructive narrative, partaking somewhat of the nature of
autobiography and yet distinct from it, in this, that its chief object, as alleged by the
writer, is not so much to recount the events of his own life, as to perform the office of
chronicler for others with whom he came in contact and was long associated.
The "Life of Sir Henry Holland " is one to be recollected, and he has not erred in giv-
ing an outline ot it to the public."— The Lancet.
" His memory was — is, we may say, for he is still alive and in possession of all his
faculties— stored with recollections o'f the most eminent men and women of this cen-
tury. ... A life extending over a period of eighty-four years, and passed in the most
active manner, in the midst of the best society, which the world has to offer, must neces-
sarily be full of singular interest: and Sir Henry Holland has fortunately not waited until
his memory lost its freshness before recalling some of the incidents in it."— The Sew
York Times.
HOWE.
Emergencies, and How to Treat Them.
The Etiology, Pathology, and Treatment of Accidents,
Diseases, and Cases of, Poisoning, which demand
Prompt Attention. Designed for Students and Prac-
titioners of Medicine.
By JOSEPH W. HOWE, M. D.,
Visiting Surgeon to Charity Hospital ; Lecturer on Surgery in the Medical Department of
the University of New York, etc.
1 vol., 8vo. 265 pp. Cloth, $3.00.
This volume is designed as a guide in the treatment of cases of emergency occurring in
medical, surgical, or obstetrical practice. It combines all the important subjects, giving
special prominence to points of practical interest in preference to theoretical considera-
tions, and uniting, with the results of personal observation, the latest views of European
and American authorities.
"The style is concise, perspicuous, and definite. Each article is written as though that
particular emergency were present; there is no waste of words, nor temporizin^ with
remedies of doubtful efficacy. The articles on oedema slottidis. asphvxia, and strangulated
herma, are particularly clear and practical, and furnish all the information required in the
managemant of those urgent cases.
"It will be found invaluable to students and young practitioners, in supplvin"- them
with an epitome of useful knowledge obtainable from no other single work: while'to the
older members of the profession it will serve as a reliable and l ready remembrancer ' "-
77ie Medtcal Etcord.
D. Appleton & Go's Medical Publications.
HUXLEY AND YOUMANS.
The Elements of Physiology and
Hygiene. With Numerous Illustrations.
By THOMAS H. HUXLEY, LL. D., F. E. S., and
WILLIAM JAY YOUMANS, M.D.
1 vol., 12mo. 420 pp, $1,75.
A text-book for educational institutions, and a valuable elementary
work for students of medicine. The greater portion is from the pen of
Professor Huxley, adapted by Dr. Youmans to the circumstances and
requirements of American education.
" A valuable contribution to anatomical and physiological science." — Religious
Telescope.
"A clear and well-arranged work, embracing the latest discoveries and ac-
cepted theories." — Buffalo Commercial.
" Teeming with information concerning the human physical economy." —
Evening Journal.
HUXLEY.
The Anatomy of Vertebrated Animals,
By THOMAS HENRY HlfXLEY, LL. D., F. R. S.,
Author of "Man's Place in Nature," "On the Origin of Species," " Lay Sermons and
Addresses," etc.
1 vol., 12mo. Cloth, $2-00.
The former works of Prof. Huxley leave no room for doubt as to the impor-
tance and value of his new volume. It is one which will be very acceptable to all
who are interested in the subject of which it treats.
SPECIMEN OF ILLUSTRATIONS.
The Alligator Terrapene (Chelydra Serpentina).
"This long-expected work will "be cordially welcomed "by all students and teachers of
Comparative Anatomy as a compendious, reliable, and, notwithstanding its email dimen-
sions, most comprehensive guide on the subject of w^iich it treats. To praise or to criti-
cise the work of so accomplished a master of his favorite science would 90 equally out of
place. It is enough to say that it realizes, in a remarkable degree, the anticipations which
have been formed of it; and that it presents an extraordinary combination of wide, gen-
eral views, with the clear, accurate, and succinct statement of a prodigious number of
individual facts."— Nature.
D. Appleton & Co?s Medical Publications.
JOHNSOK
The Chemistry of Common Life.
Illustrated with numerous Wood Engravings.
By JAMES F. JOHNSON, M. A., F. R. S., F. G. S., ETC., ETC.,
Author of "Lectures on Agricultural Chemistry and Geology," "A Catechism of Agricultural
Chemistry and Geology,'1 etc,
2 vols., 12mo. Cloth, $3.00.
It has been the object of the author in this work to exhibit the
present condition of chemical knowledge, and of matured scientific
opinion, upon the subjects to which it is devoted. The reader will not
be surprised, therefore, should he find in it some things which differ
from what is to be found in other popular works already in his hands or
on the shelves of his library.
LETTERMAN.
Medical Recollections of the Army of
the Potomac.
By JONATHAN LETTERMAN, M. D.,
Late Surgeon U. S. A^, and Medical Director of the Army of the Potomac.
1 vol., 8vo. 194 pp. Cloth, $1.00.
" This account of the medical department of the Army of the Poto-
mac has been prepared, amid pressing engagements, in the hope that
the labors of the medical officers of that army may be known to an in-
telligent people, with whom to know is to appreciate ; and as an affec
tionate tribute to many, long my zealous and efficient colleagues, who,
in days of trial and danger, which have passed, let us hope never to re-
turn, evinced their devotion to their country and to the cause of hu-
manity, without hope of promotion or expectation of reward." — Preface.
" We venture to assert that but few who open this volume of medical annals,
pregnant as they are with instruction, will care to do otherwise than finish them
at a sitting." — Medical Record.
" A graceful and affectionate tribute." — N". T. Medical Journal
LEWES.
The Physiology of Common Life.
By GEORGE HENRY LEWES,
Author of "Seaside Studies," "Life of Goethe," etc.
2 vols., 12mo. Cloth, $3.00.
The object of this work differs from that of all others on popular
science in its attempt to meet the wants of the student, while meeting
those of the general reader, who is supposed to be wholly unacquainted
with anatomy and physiology.
D. Appleton <& CoSs Medical Publications.
MAUDSLEY.
The Physiology and Pathology of the
Mind.
By HENRY MAUDSLEY, M. D., LOITDON,
Physician to the "West London Hospital; Honorary Member of the Medico-Psychological Society
of Paris ; formerly Resident Physician of the Manchester Eoyal Lunatic Hospital, etc.
1 vol., 8vo. 442 pp. Cloth, $3,50.
This work aims, in the first place, to treat of mental phenomena from
a physiological rather than from a metaphysical point of view ; and,
secondly, to bring the manifold instructive instances presented by the
unsound mind to bear upon the interpretation of the obscure problems
of mental science.
" Dr. Maudsley has had the courage to undertake, and the skill to execute,
what is, at least in English, an original enterprise." — London Saturday Review.
" It is so full of sensible reflections and sound truths that their wide dissemi-
nation could not but be of benefit to all thinking persons." — PsychologicalJournal.
"Unquestionably one of the ablest and most important works on the subject
of which it treats that has ever appeared, and does credit to his philosophical
acumen and accurate observation." — Medical Record.
" We lay down the book with admiration, and we commend it most earnestly
to our readers as a work of extraordinary merit and originality — one of those
productions that are evolved only occasionally in the lapse of years, and that
serve to mark actual and very decided advances in knowledge and science." —
N. Y. Medical Journal.
Body and Mind : An Inquiry into their Con-
nection and Mutual Influence, specially in reference
to Mental Disorders ; ~being the Gulstonian Lectures
for 1870, delivered "before the Royal College of
Physicians. With Appendix.
By HENRY MAUDSLEY, M. D., LONDON,
Fellow of the Eoyal College of Physicians ; Professor of Medical Jurisprudence in University Col-
lege. London ; President-elect 'of the Medico-Psychological Association ; Honorary Member of
the Medico-Psychological Society of Paris, of the Imperial Society of Physicians of Vienna,
and of the Society for the Promotion of Psychiatry and Forensic Psychology of Vienna ;
formerly Besident Physician of the Manchester Eoyal Lunatic Asylum, etc., etc.
1 vol., 12mo. 155 pp. Cloth, $1.00.
The general plan of this work may be described as being to bring
man, both in his physical and mental relations, as much as possible with-
in the scope of scientific inquiry.
" A representative work, which every one must study who desires to know
what is doing in the way of real progress, and not mere chatter, about mental
physiology and pathology." — The Lancet.
" It distinctly marks a step in the progress of scientific psychology." — The
Practitioner.
D. Appleton & CoSs Medical Publications.
MAKKOE.
A Treatise on Diseases of the Bones.
By THOMAS M. MARKOE, M. 0.,
Professor of Surgery in the College of Physicians and Surgeons, New York, etc.
WITH NUMEROUS ILLUSTRATIONS.
1 vol. 8vo. Cloth, $4.50.
SPECIMEN OF ILLUSTRATIONS.
This valuable work is a treatise on Diseases of the Bones, embracing their
structural changas as affected by disease, their clinical history and treatment, in-
cluding also an account of the various tumors which grow in or upon them.
Xone of the injuries of bone are included in its scope, and no joint diseases, ex-
cepting where the condition of the bone is a prime factor in the problem of
disease. As the work of an eminent surgeon of large and varied experience, it
imy be regarded as the best on the subject, and a valuable contribution to medi-
cal literature.
" The book which I now offer to my professional brethren contains the substance of
the lectures which I have delivered during the past twelve years at the college. ... I
have followed the leadings of my own studies and observations, dwelling more on those
branches where I had seen and studied most, and perhaps too much neglecting others
where my own experience was more barren, and therefore to me less interesting. I have
endeavored, however, to make up the deficiencies of my own knowledge by the free use of
the materials scattered so richly through our periodical literature, which scattered
leaves it is the right and the duty of the systematic writer to collect and to embody in
any account he may offer of the state of a science at any given period."— Extract from
Author's Preface.
D. Appleton & CoSs Medical Publications.
MEYER
Electricity in its Relations to Practical
Medicine.
By DE. MORITZ MEYER,
Eoyal Counsellor of Health, etc.
Translated from the Third German Edition, with Notes and Additions,
A New and Revised Edition,
By WILLIAM A. HAMMOND, M. D.,
Professor of Diseases of the Mind and Nervous System, and of Clinical Medicine, in the Bellevue
Hospital Medical College; Vice-President of the Academy of Mental Sciences, National
Institute of Letters, Arts, and Sciences ; late Surgeon-General U. S. A., etc.
1 vol., 8vo. 497 pp. Cloth, $4.50.
" It is the duty of every physician to study the action of electricity,
to become acquainted with its value in therapeutics, and to follow the
improvements that are being made in the apparatus for its application in
medicine, that he may be able to choose the one best adapted to the
treatment of individual cases, and to test a remedy fairly and without
prejudice, which already, especially in nervous diseases, has been used
with the best results, and which promises to yield an abundant harvest
in a still broader domain." — From Author's Preface.
SPECIMEN OF ILH78TBATION8.
Saxton-Ettinghausen Apparatus.
" Those who do not read German are under great obligations to William A.
Hammond, who has given them not only an excellent translation of a most ex-
cellent work, but has given us much valuable information and many suggestions
from his own personal experience." — Medical Record.
" Dr. Moritz Meyer, of Berlin, has been for more than twenty years a laborious
and conscientious student of the application of electricity to practical ^ medicine,
and the results of his labors are given in this volume. Dr. Hammond, in making
a translation of the third German edition, has done a real service to the profession
of this country and of Great Britain. Plainly and concisely written, and simply
and clearly arranged, it contains just what the physician wants to know on the
subject." — N. T. Medical Journal
" It is destined to fill a want long felt by physicians in this country." — Journal
of Obstetrics.
D. Appleton & (70. 's Medical Publications.
NIEMEYER
A Text-Book of Practical Medicine.
With Particular Reference to Physiology and Patho-
logical Anatomy.
By the late Dr. FELIX YON NIEMEYER,
Professor of Pathology and Therapeutics; Director of the Medical Clinic of the University of
Tubingen.
Translated from tlie Eighth German Edition, by special permission of
the Author,
By GEORGE H. HUMPHREYS, M. D.,
Late one of the Physicians to the Bureau of Medical and Surgical Relief at Bellevue Hospital for
the Out-door Poor ; Fellow of the New York Academy of Medicine, etc.,
and
CHARLES E. HACKLEY, M. D.,
One of the Physicians to the New York Hospital; one of the Surgeons to the New York Eye
and Ear Infirmary ; Fellow of the New York Academy of Medicine, etc.
Bevised Edition. 2 vols., 8vo, 1,528 pp. Cloth, $9.00 ; Sheep, $11.00.
The author undertakes, first, to give a picture of disease which shall
be as lifelike and faithful to nature as possible, instead of being a mere
theoretical scheme; secondly, so to utilize the more recent advances
of pathological anatomy, physiology, and physiological chemistry, as to
furnish a clearer insight into the various processes of disease.
The work has met with the most flattering reception and deserved
success ; has been adopted as a text-book in many of the medical colleges
both in this country and in Europe; and has received the very highest
encomiums from the medical and secular press.
"It is comprehensive and concise, and is characterized by clearness and
originality." — Dublin Quarterly Journal of Medicine.
" Its author is learned in medical literature ; he has arranged his materials
with care and judgment, and has thought over them." — The Lancet.
"As a full, systematic, and thoroughly practical guide for the student and
physician, it is not excelled by any similar treatise in any language." — Appletons1
Journal.
" The author is an accomplished pathologist and practical physician ; he is not
only capable of appreciating the new discoveries, which during the last ten years
have been unusually numerous and important hi scientific and practical medicine,
but, by his clinical experience, he can put these new views to a practical test, and
give judgment regarding them." — Edinburgh Medical Journal.
" From its general excellence, we are disposed to think that it will soon take
its place among the recognized text-books." — American Quarterly Journal of
Medical Sciences.
" The first inquiry in this country regarding a German book generally is, ' la
it a work of practical value ? " Without stopping to consider the justness of the
American idea of the ' practical,' we can unhesitatingly answer, ' It is ! ' " — New
York Medical Journal.
" The author has the power of sifting the tares from the wheat — a matter of
the greatest importance hi a text-book for students." — British Medical Journal.
" Whatever exalted opinion our countrymen may have of the author's talents
of observation and his practical good sense, his text-book will not disappoint
them, while those who are so unfortunate as to know him only by name, have hi
store a rich treat." — New York Medical Record,
D. Appleton & CoSs Medical Publications.
NEUMANN.
Hand-Book of Skin Diseases.
By DR. ISIDOR NEUMANN,
Lecturer on Skin Diseases in the Royal University of Vienna.
Translated from advanced sheets of the second edition, furnished by the
Author; with Notas,
By LUCIUS D. BULKLEY, A. M., M. D.,
Surgeon to the New York Dispensary, Department of Venereal and Skin Diseases ; Assist-
ant to the Skin Clinic of the College of Physicians and Surgeons, New York; Mem-
ber of the New York Dermatological Society, etc., etc.
1 vol., 8vo. AbDut 45D pages and 66 Woodcuts. Cloth, $4.00.
SPECIMEN OF ILLUSTRATIONS.
Section of skin from a bald head.
Prof. Neumann ranks second only to Hebra, whose assistant he was for many years,
and his work may be considered as a fair exponent of the German practice of Dermatolo-
gy. The book is abundantly illustrated with plates of the histology and pathology of the
skin. The translator has endeavored, by means of notes from French, English, and Ameri-
can sources, to make the work valuable to the student as well as to the practitioner.
"It is a work which I shall heartily recommend to my class of students at the Univer-
sity of Pennsylvania, and one which I feel sure will do much toward enlightening the pro-
fession on this subject." — Louis A. Duhring.
" I know it to be a good book, and I am sure that it is well translated ; and it is inter-
esting to find it illustrated by references to the views of co-laborers in the same field."—
Erasmus Wilson.
" So complete as to render it a mo?t useful book of reference."— T. McCatt Anderson.
" There certainly is no work extant which deals so thoroughly with the Pathological
Anatomy of the Skin as does this hand-book." — N. Y. Medical Record.
" The original notes by Dr. Bulkley are very practical, and are an important adjunct to
the text. ... I anticipate for it a wide circulation."—^^ DurJcee. Boston.
" I have already twice expressed my favorable opinion of the book in print, and am
glad that it is given to the public at last."— James C. White, Boston.
" More than two years ago we noticed Dr. Neumann's admirable work in its original
shape ; and we are therefore absolved from the necessity of saying more than to repeat
our strong recommendation of it to English readers."— Practitioner.
D. Appleton & (70. 's Medical Publications.
HOLLAND.
Recollections of Past Life,
By SIR HENRY HOLLAND, Bart, M. D., F. R. S., K. C. B., etc.,
President of the Royal Institution of Great Britain, Physician-in-Ordinary to the Queen,
etc., etc.
1 vol., 12mo, 351 pp. Price, Cloth, $2.00.
A very entertaining and instructive narrative, partaking somewhat of the nature of
autobiography and yet distinct from it, in this, that its chief object, as alleged by the
writer, is not so much to recount the events of his own life, as to perform the office of
chronicler for others with whom he came in contact and was long associated.
The "Life of Sir Henry Holland " is one to be recollected, and he has not erred in giv-
ing an outline ot it to the public." — The Lancet.
" His memory was — is, we may say, for be is still alive and in possession of all his
faculties — stored with recollections of the most eminent men and women of this cen-
tury. ... A life extending over a period of eighty-four years, and passed in the most
active manner, in the midst of the best society, which the world has to offer, must neces-
sarily be fall of singular interest ; and Sir Henry Holland has fortunately not waited until
his memory lost its freshness before recalling some of the incidents in it." — The New
York Times.
HOWE.
Emergencies, and How to Treat Them.
The Etiology, Pathology, and Treatment of Accidents,
Diseases, and Cases of Poisoning, which demand
Prompt Attention. Designed for Students and Prac-
titioners of Medicine.
By JOSEPH W. HOWE, M. D.,
Visiting Surgeon to Charity Hospital ; Lecturer on Surgery in the Medical Department of
the University of New York, etc.
1 vol., 8vo. 265 pp. Cloth, $3.00,
This volume is designed as a guide in the treatment of cases of emergency occurring in
medical, surgical, or obstetrical practice. It combines all the important subjects, giving
special prominence to points of practical interest in preference to theoretical considera-
tions, and uniting, with the results of personal observation, the latest views of Enropean
and American authorities.
"The style is concise, perspicuous, and definite. Each article is written as though that
particular emergency were present; there is no waste of words, nor temporizing with
remedies of doubtful efficacy. The articles on oedema glottidis. asphvxia, and strangulated
hernia, are particularly clear and practical, and furnish all the information required7 in the
management of those urgent cases
_ "It will be found invaluable to students and young practitioners, in supplying them
with an epitome of useful knowled<re obtainable from no other single work: while" to the
older members of the profession it will serve as a reliable and ' ready remembrancer ' "-
The Medical Record.
D. Appleton & Go's Medical Publications.
MAUDSLEY.
The Physiology and Pathology of the
Mind.
By HENRY MAUDSLEY, M. D., LOITDON,
Physician to the West London Hospital; Honorary Member of the Medico-Psychological Society
of Paris ; formerly Eesident Physician of the Manchester Koyal Lunatic Hospital, etc.
1 vol., 8vo. 442 pp. Cloth, $3.50.
This work aims, in the first place, to treat of mental phenomena from
a- physiological rather than from a metaphysical point of view ; and,
secondly, to bring the manifold instructive instances presented by the
unsound mind to bear upon the interpretation of the obscure problems
of mental science.
" Dr. Maudsley has had the courage to undertake, and the skill to execute,
what is, at least in English, an original enterprise." — London Saturday Review.
" It is so full of sensible reflections and sound truths that their wide dissemi-
nation could not but be of benefit to all thinking persons." — PsychologicalJournal.
" Unquestionably one of the ablest and most important works on the subject
of which it treats that has ever appeared, and does credit to his philosophical
acumen and accurate observation." — Medical Record,
" We lay down the book with admiration, and we commend it most earnestly
to our readers as a work of extraordinary merit and originality — one of those
productions that are evolved only occasionally in the lapse of years, and that
serve to mark actual and very decided advances in knowledge and science." —
N~. Y. Medical Journal.
Body
and Mind I An Inquiry into their Con-
nection and Mutual Influence, specially in reference
• to Mental Disorders ; being the Gulstonian Lectures
for 1870, delivered before the Royal College of
Physicians. With Appendix.
By HENRY MAUDSLEY, M. D., LONDON,
Fellow of the Eoyal College of Physicians ; Professor of Medical Jurisprudence in University Col-
lege, London ; President-elect of the Medico-Psychological Association ; Honorary Member of
the Medico-Psychological Society of Paris, of the Imperial Society of Physicians of Vienna,
and of the Society for the Promotion of Psychiatry and Forensic Psychology of Vienna ;
formerly Kesident Physician of the Manchester Royal Lunatic Asylum, etc., etc.
1 vol., 12mo. 155 pp. Cloth, $1.00.
The general plan of this work may be described as being to bring
man, both in his physical and mental relations, as much as possible with-
in the scope of scientific inquiry.
" A representative work, which every one must study who desires to know
what is doing in the way of real progress, and not mere chatter, about mental
physiology and pathology." — The Lancet.
"It distinctly marks a step in the progress of scientific psychology." — The
Practitioner.
D. Appleton & Co?s Medical Publications.
MAKKOE.
A Treatise on Diseases of the Bones.
By THOMAS M. MARKOE, M. D.,
Professor of Surgery in the College of Physicians and Surgeons, New York, etc.
WITH NUMEROUS ILLUSTRATIONS.'
1 vol. 8vo. Cloth, $4.50.
SPECIMEN OF ILLUSTRATIONS.
This valuable work is a treatise on Diseases of the Bones, embracing their
structural changes as affected by disease, their clinical history and treatment, in-
cluding also an account of the various tumors which grow in or upon them.
None of the injuries of bone are included in its scope, and no joint diseases, ex-
cepting where the condition of the bone is a prime factor in the problem of
disease. As the work of an eminent surgeon of large and varied experience, it
may be regarded as the best on the subject, and a valuable contribution to medi-
cal literature.
"The book which I now offer to my professional brethren contains the substance of
the lectures which I have deliverer] duringr the past twelve years at the college. ... I
have followed the leadinss of my own studies and observations, dwelling more on those
branches where I had seen and studied most, and perhaps too much neglecting others
where my own experience was more barren, and therefore to me less interesting. I have
endeavored, however, to make up the deficiencies of my own knowledge by the free use of
the materials scattered so richly through our periodical literature, which scattered
leaves it is the right and the duty of the systematic writer to collect and to embody in
any account he may offer of the state of a science at any given period."— Extract from
Author'1 s Preface.
D. Appleton & CoSs Medical Publications.
MEYER
Electricity in its Relations to Practical
Medicine.
By DE. MOKITZ MEYER,
Eoyal Counsellor of Health, etc.
Translated from, the Third German Edition, with Notes and Additions,
A New and Revised Edition,
By WILLIAM A. HAMMOND, M. D.,
Professor of Diseases of the Mind and Nervous System, and of Clinical Medicine, in the Bellevue
Hospital Medical College; Vice-President of the Academy of Mental Sciences, National
Institute of Letters, Arts, and Sciences ; late Surgeon-General U. S. A., etc.
1 vol., 8vo. 497 pp. Cloth, $4.50.
"It is the duty of every physician to study the action of electricity,
to become acquainted with its value in therapeutics, and to follow the
improvements that are being made in the apparatus for its application in
medicine, that he may be able to choose the one best adapted to the
treatment of individual cases, and to test a remedy fairly and without
prejudice, which already, especially in nervous diseases, has been used
with the best results, and which promises to yield an abundant harvest
in a still broader domain." — From Author's Preface.
SPECIMEN OP ILLUSTRATIONS.
Saxton-Ettinghausen Apparatus.
" Those who do not read German are under great obligations to William A.
Hammond, who has given them not only an excellent translation of a most ex-
cellent work, but has given us much valuable information and many suggestion?
from his own personal experience. "-^Medical Record.
" Dr. Moritz Meyer, of Berlin, has been for more than twenty years a laborious
and conscientious student of the application of electricity to practical medicine,
and the results of his labors are given in this volume. Dr. Hammond, in making
a translation of the third German edition, has done a real service to the profession
of this country and of Great Britain. Plainly and concisely written, and simply
and clearly arranged, it contains just what the physician wants to know on the
subject." — N. T. Medical Journal.
" It is destined to fill a want long felt by physicians in this country." — Journal
of Obstetric*.
D. Appleton & CoSs Medical Publications.
NIEMEYER.
A Text-Book of Practical Medicine.
With Particular Reference to Physiology and Patho-
logical Anatomy.
By the late Dr. FELIX VON NIEMEYEK,
Professor of Pathology and Therapeutics; Director of the Medical Clinic of the University of
Tubingen.
Translated from the Eighth German Edition, by special permission of
the Author,
By GEORGE H. HUMPHREYS, M. D.,
Late one of the Physicians to the Bureau of Medical and Surgical Relief at BeUevue Hospital for
the Out-door Poor ; Fellow of the New York Academy of Medicine, efcx,
and
CHARLES E. HACKLEY, M. D.,
One of the Physicians to the New York Hospital; one of the Surgeons to the New York Eye
and Ear Infirmary ; Fellow of the New York Academy of Medicine, etc.
Revised Edition. 2 vols., 8vo. 1,528 pp. Cloth, $9.00 ; Sheep, $11.00.
The author undertakes, first, to give a picture of disease which shall
be as lifelike and faithful to nature as possible, instead of being a mere
theoretical scheme ; secondly, so to utilize the more recent advances
of pathological anatomy, physiology, and physiological chemistry, as to
furnish a clearer insight into the various processes of disease.
The work has met with the most flattering reception and deserved
success ; has been adopted as a text-book in many of the medical colleges
both in this country and in Europe; and has received the very highest
encomiums from the medical and secular press»
" It is comprehensive and concise, and is characterized by clearness and
originality." — Dublin Quarterly Journal of Medicine.
u Its author is learned in medical literature ; he has arranged his materials
with care and judgment, and has thought over them/'-^^TAc Lancet.
" As a full, systematic, and thoroughly practical guide for the student and
physician, it is not excelled by any similar treatise hi any language." — Appldons*
Journal.
" The author is an accomplished pathologist and practical physician ; he is not
only capable of appreciating the new discoveries, which during the last ten years
have been unusually numerous and important in scientific and practical medicine^
but, by his clinical experience, he can put these new views to a practical test, and
give judgment regarding them." — Edinburgh Medical Journal.
" From its general excellence, we are disposed to think that it will soon take
its place among the recognized text-books. "—American Quarterly Journal of
Medical Sciences.
" The first inquiry in this country regarding a German book generally is, ' Is
it a work of practical value ? " Without stopping to consider the justness of the
American idea of the ' practical,' we can unhesitatingly answer, ' It is ! ' " — New
York Medical Journal.
" The author has the power of sifting the tares from the wheat — a matter of
the greatest importance in a text-book for students." — British Medical Journal.
" Whatever exalted opinion our countrymen may have of the author's talents
of observation and his practical good sense, his text-book will not disappoint
them, while those who are so unfortunate as to know him only by name, have in
store a rich treat." — New York Medical Record
D. Applet on & (70. 's Medical Publications.
NEUMANN.
Hand-Book of Skin Diseases.
By DR. ISIDOR NEUMANN,
Lecturer on Skin Diseases in the Koyal University of Vienna.
Translated from advanced sheets of the second edition, furnished by the
Author ; with Notes,
By LUCIUS D. BULKLEY, A. M., M. D.,
Surgeon to the New York Dispensary, Department of Venereal and Skin Diseases ; Assist-
ant to the Skin Clinic of the College of Physicians and Surgeons, New York; Mem-
ber of the New York Dermatological Society, etc., etc.
1 vol., 8vo. About 450 pages and 66 Woodcuts. Cloth, $4.00.
SPECIMEN OP ILLUSTRATIONS.
Section of skin from a bald head.
Prof. Neumann ranks second only to Hebra, whose assistant he was for many years,
and his work may be considered as a fair exponent of the German practice of Dermatolo-
gy. The book is abundantly illustrated with plates of the histology and pathology of the
skin. The translator has endeavored, by means of notes from French, English, and Ameri-
can sources, to make the work valuable to the student as well as to the practitioner.
" It is a work which I shall heartily recommend to my class of students at the Univer-
sity of Pennsylvania, and one which I feel sure will do much toward enlightening the pro-
fession on this subject."— Louis A. Duhring.
" I know it to be a good book, and I am sure that it is well translated ; and it is inter-
esting to find it illustrated by references to th,e views of co-laborers in the same field/' —
Erasmus Wilson.
" So complete as to render it a most useful book of reference."— T. McCatt Anderson.
"There certainly is no work extant which deals so thoroughly with the Pathological
Anatomy of the Skin as does this hand-book."—^. T. Medical Record.
"The original notes by Dr. Bulkley are very practical, and are an important adjunct to
the text. ... I anticipate for it a wide circulation."— Silas Durkee, Boston.
"I have already twice expressed my favorable opinion of the book in print, and am
glad that it is given to the public at last." — James C. White, Boston.
"More than two years ago we noticed Dr. Neumann's admirable work in its original
shape ; and we are therefore absolved from the necessity of saying more than to repeat
our strong recommendation of it to English readers."— Practitioner.
UNIVERSITY OF CALIFORNIA
MEDICAL SCHOOL LIBRARY
THIS BOOK IS DUE ON THE LAST DATE
STAMPED BELOW
Books not returned on time are subject to a fine of 50c
per volume after the third day overdue, increasing to
$1.00 per volume after the sixth day. Books not in de-
mand may be renewed if application is made before expi-
ration of loan period.
3m-2,'37
. LIBRARY
Live Music Archive
Librivox Free Audio
Metropolitan Museum
Cleveland Museum of Art
Internet Arcade
Console Living Room
Books to Borrow
Open Library
TV News
Understanding 9/11