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• 
PSYCHIATRY
A CLINICAL TREATISE ON
Diseases of the  Fore-Brain
BASED UPON
A STUDY OF ITS  STRUCTURE,  FUNCTIONS, AND NUTRITION
        THEODOR meynert, M.D.
PROFESSOR OF NERVOUS DISEASES AND CHIEF OF THE PSYCHIATRIC CLINIC IN VIENNA
      TRANSLATED (UNDER AUTHORITY OF THE AUTHOR) BY


                B. SACHS. M.D.
INSTRUCTOR IN DISEASES OF THE MIND AND NERVOUS SYSTEM IN THE NEW YORK POLYCLINIC
                   PART I.

The Anatomy, Physiology, and Chemistry of the Brain
    NEW YORK AND LONDON
G. P.  PUTNAM'S  SONS
     (T|jc Jlmciurbocher |lrrss
           1885 
fc
IAgijs
r
    COPYRIGHT BY
G. P. PUTNAM'S SONS
       1885
    Press of
G. P. Putnam's Sons
   New York 
TRANSLATOR'S  PREFACE.
   I HAVE  no apologies to offer for presenting this  American
edition  of  Professor  Meynert's  " Psychiatry"  to the  English
medical public.   It is a scientific treatise on diseases of the mind
by the one best fitted to write such a treatise.  To  most medical
men Meynert is known as the great brain-anatomist.  This book
may serve  incidentally  as a text-book on the anatomy of the
brain ;  but it is not merely that.   I would direct particular atten-
tion  to  the subsequent chapters of this treatise, from which the
students of psychiatry,  of physiology, and  of  psychology  may
gather much information and much food for reflection.
   For  the shortcomings of my translation, I  crave the indul-
gence of the reader.  I am quite certain  that those best acquainted
with the  original will  not underrate the difficulties of the  task,
and  will be most lenient  in  passing judgment  upon my errors.
That there are  such, I do not doubt.   It has been my aim to
furnish  a  readable translation of this treatise, and to accomplish
this, the attempt at a literal translation had to be abandoned.   I
trust, however,  that  I have in  no instance departed from the
sense of the original.
   In regard to the encephalic nomenclature employed in the first
section  of this volume, I would  say that I have coined but very
few  new terms;  and  that I have either used  such terms as are
familiar to all English  students  of  cerebral anatomy,  or  have
retained the Latin terms used by the  author.   The latter was
done with the view of  avoiding a conflict between the text and
the  author's plates.
   In order to make this  volume complete in  itself, I have pre-
pared a special index to the subject-matter therein discussed.  A
similar index will be added to Part II.
   My special thanks are gladly given to my  friend, Dr. M. Allen
Starr, of this city, for  his  kind assistance in  revising proof;  and
                              iii 
IV
Psychiatry.
to the publishers, Messrs. G. P. Putnam's Sons, for their generous
efforts to make this translation worthy of the original.
   If the work now given to the public will advance the cause of
psychiatry in this country and in England, I shall feel that I have
in some small measure acknowledged the debt of gratitude I owe
to my former master, the author.
                                           B. Sachs, M.D.

   28 East Sixty-second Street,
      New York, October 12, 1885. 
AUTHOR'S  PREFACE.
   The  reader will find  no other definition of " Psychiatry " in
this book but the one given on  the title-page: " Clinical Treatise
on Diseases of the Fore-Brain."   The historical term psychiatry,
i. e. " treatment of the soul," implies more than we  can accom-
plish, and transcends the  bounds of accurate scientific  investiga-
tion.
   Were  I  to  give a functional  designation to  the  morbid
affections of the fore-brain, I would  choose the term " Diseases
of the Mind."  And on this term I would insist in order to avoid
the common fallacy that  it is permissible to  regard the contents
of cortical   memories as  paled  sensory  images,  although we
acknowledge the origin of these memories from external sensory
stimuli.   We shall  show in  this  book that the fore-brain  can
neither give rise to hallucinatory phenomena, nor  that its func-
tional manifestations, the so-called " memories," are possessed of
the slightest sensory qualities.   It would be better, therefore, to
speak of memory-symbols.  In our memory of  the most glaring
sunlight, of the most intense roll of thunder, there is not as much
as the billionth part of the light of a glow-worm, or of  the sound
produced by the falling of a hair upon water.  But  is  there  any
other word in  our language with which to designate phenomena
devoid of all sensory qualities, but the word " psychical "?
   This most conspicuous fact regarding the .functional activity
of the fore-brain accentuates the difference between the abstract
and  material character of our  concepts.  The latter  is lacking
altogether,  and is  purely a matter of external perception.   But
the centres for such perception  are in the basal portions of the
brain, and not in the/^r^-brain.   The entire fore-brain I designate
generally as cortex, for the conducting elements of  the fore-brain
__the axial  fibres—are  prolongations of the cortical  cells,  and,
therefore, part of the cortex proper.   Those divisions of the brain
which effect  sensory perceptions, without  the aid of the  fore-
brain, and which are concerned particularly with the execution of 
VI
Psychiatry.
reflex movements (in the broadest sense of that term), are  desig-
nated, by way of antithesis, as subcortical centres.   This antithesis
will be evident also in the different degrees of excitation (of these
different centres), and will furnish us with  the most  important
clue to the understanding of the activity of the cerebral mechan-
ism under morbid conditions of the mind.
   I have not, and never had, the slightest inclination for making
books.  To this effort I was impelled by the conviction that there
was need of a scientific treatise on  mental diseases in spite of the
present large literature on the subject.   The  least doubt as to the
correctness of any views expounded in this book induced me to
stop, and  to interrupt work until  I had satisfied  myself of the
correctness  of those views by scientific  investigation and reflec-
tion.  This will explain why so many years have elapsed from the
time the book was begun (in  1877) to the date of its publication.
   The title-page refers to the fundamental studies indispensable to
an understanding of the clinical manifestations of mental diseases.
My intention of elucidating diseases of the fore-brain in this way
is based upon the conviction that our knowledge of them  should
be obtained, as all  sound clinical  knowledge is acquired, by a
study of the structure, the function, and the nutrition of  each
organ.   Hitherto the science  of psychiatry  has been too largely
subjective.  Many of its  teachings, which are not  based upon
the studies just referred to, had  better be forgotten.  Naturally
enough a knowledge of clinical phenomena  precedes in time the
knowledge of the fundamental facts underlying these phenomena.
Morbid  symptoms  are not  recognized  by  their  scientific sub-
stratum, but in  studying this  substratum we are actuated  by the
desire to fathom the phenomena of disease.   It follows, therefore,
that the first half' of the present work is suggested by the second,
clinical, half;  and the  subjects discussed in these fundamental
chapters are chosen with a view to the  thorough  understanding
of the clinical  facts.  These chapters constitute  an integral part
of this clinical  treatise, and are not an adjunct  to it.  This, we
take it, is a novel and legitimate feature of the book.
   The  number of  clinical cases upon which my views rest is not
only sufficient to base original conclusions upon, but  by reason of
their large numbers, these cases seem to me to be absolutely con-
vincing.   In 1875 I was fortunate enough to be able to change my
clinic at the Vienna Provincial Insane Asylum, where there was but
1 Part I. of the translation. 
Author s Preface.
vn
a slight change in the  number and character of the inmates, for
the Psychiatric Clinic of the Vienna General Hospital.  My present
"clinic" is the only State Insane Asylum of Austria, though its
quarters are not  in keeping with its importance.  Fourteen to
sixteen  hundred  patients are received  annually into this clinic,
and of  these, only those who are inhabitants of Lower Austria
are  soon dismissed and assigned to other institutions.  It was
the study of such a vast number of cases  which convinced me
that many cases  could not be properly classified according to the
old rules and within the artificial  types of mental diseases.   The
many variations  from these types appeared not only to favor, but
actually  to  compel, the establishment  of  a  natural system  of
classification.
    During the interval that elapsed between the  inception and
completion  of my book, I have  seen reason  to  depart  in  some
respects from the account here given of the  anatomy of the brain.
 I have not  adopted any new method, but  have elaborated with
 greater care  the old cleavage (Abfaserung)  method of my prede-
 cessors,—a laborious  method, which has been unduly  crowded
 out by the study of brain-sections.  The former method supplies
 us not only with a key to the complexities of brain-sections, but
 enables us also to extend our knowledge of the minute  anatomy
 of the brain beyond  the information we can  obtain from micro-
 scopical sections.  From the notes to be  appended to the end of
 this work,1 the reader will gather wherein  my views have been
 necessarily modified  or supplemented  by  the investigations  of
 other  authors and my  latest researches.   The  most important
 results  which I  have  recently arrived  at  are in  regard to the
 cortical and ganglionic fibres of origin of th.e pes pedunculi (crusta),
 and the connection of these fibres with the pyramids.  My dissent
 from the adoption of a common system of  cranial measurements,
 to which I agreed, at  Ranke's suggestion, is explained by the fact
 that the chapter 2 on  pathological craniology  was written as early
 as 1880.
     In view of the necessity  of starting from anatomical facts, I
 have endeavored, in every case, not only to  give due weight  to
 the structure of the brain as the fundamental basis for the various
 forms of disease, but  have endeavored,  with  the same end in
 view, to insist upon  and to explain every visible symptom ex-
 hibited by the patient.   This refers  to the consideration of move-
1 In Part II. of this edition. 
viii                      Psychiatry.
ments of expression as well, which have not been properly utilized
hitherto as aids to diagnosis.  Thus in spite of the frequent smiles
to be observed in stuporous  patients during  maniacal  moods,
stuporous insanity has been classified under melancholia.
   Dissatisfied with the statistical method, which laid inordinate
stress upon hereditary predisposition to disease,  I have considered
predisposition as a form of disease and not as a  condition  antece-
dent to it.   I have above  all referred to the anatomical  peculiari-
ties constituting predisposition. I was not content, as others have
been, to accept the mystical conception of heredity, but have  in-
sisted on the anatomical peculiarities in patients which constitute
predisposition.   And  these peculiarities  were inferred  not  only
from external appearances, but also from  a due  consideration of
all abnormal proportions of the body.   In an  article, published as
early as 1878, I showed that the nutrition and the excitability of
the brain must be regarded as depending  upon the  reciprocal  re-
lation existing between the weights of the brain and of the heart.
The important investigations of Benecke  and Thoma on the size
and weight of the  different organs of  the  body  appear to me to
supply a firm anatomical foundation for the doctrine of  predispo-
sition to disease.
    As regards the theory of  predisposition, and more particu-
larly the doctrine of heredity,  which has been carried to the ex-
treme of assuming the existence  of innate  ideas, and  which, in
clinical medicine, has led to the erroneous theory of  moral insan-
ity, I  have deemed it necessary to criticise, in its proper connec-
tions, Darwin's theory of  the inheritance  of acquired faculties, as
has been done before  me by other German authors, among  them
DuBois Reymond  and Weissman.   It is taking altogether too
simple a view of things, to regard morality as one of  man's talents,
and as a  definite  psychical property  which  is present in  some
persons and  lacking  in others.  Indeed,  there  is great truth in
Weissman's observation :  " Talents do not depend upon the pos-
session of any special portion of the brain ; there is nothing simple
about  them, but  they are combinations  of many and  widely
different psychical faculties."
   Just as the much-abused doctrine of hereditary predisposition
to disease casts too great  a  suspicion upon the- limits of  mental
health, so there is  possibly  the danger that this same  suspicion
might be increased by the consideration of those errors of  organi-
zation which contitute the basis of predisposition.   But thinking 
Author s Preface.
IX
physicians will  avoid  this  danger, for they will  distinguish be-
tween those who are possibly "called" to  disease, and that for-
tunately smaller number of persons who are, in the saddest sense
of the term, " chosen " for disease.   Thus  the limits of relative
health,  as they are generally conceived,  will not be narrowed
down by abstract theorizing to an intangible  line.   I  trust that
the dialectic efforts in this direction will bear fruit in the domain
of forensic medicine, and it would be gratifying to me to know
that I had contributed somewhat to this end.
Vienna, Easter, 1884.
Theodor  Meynert. 
 
CONTENTS.
                                                    PAGE
Structure and Architecture of the Brain  .    .    .    i
The Minute  Anatomy of the Brain  .....   56
Anatomical  Corollaries and  Physiology  of  Cerebral
     Architecture     ........   138
The Nutrition of the Brain    ......   213
Appendix—Machanism of Expression  .   .    .    .    .271
Index............279 
 
STRUCTURE  AND  ARCHITECTURE  OF  THE
                           BRAIN.
                   SURFACES OF THE BRAIN.

    UNTIL recently,  it was commonly believed that  no vestiges
of the  vertebrate  brain  were  to be  found in ampJiioxns  lancco-
latus.   Its  spinal  cord,  instead  of  dilating  above  into  a rudi-
mentary encephalon, was thought to terminate in conical fashion.
Rohony, however, has demonstrated  the  existence of a primary
cerebral vesicle in the amphioxus as well.   The possession  of
a brain  and  spinal  cord may, therefore, be  said  to be  charac-
teristic of all  vertebrates.  The  prosencephalon (the fore-brain),
the largest division  of the human brain,  diminishes  so rapidly in
volume as we  descend in the animal  series that even among the
simpler  mammalian forms it   does  not  in  every  case  exceed
in mass the other parts  of the brain.  In the evolution  of the
brain from the medullary tubes, the prosenceph-
alon is represented by secondary subordinate ap-
pendices of the primary cerebral  vesicle.   These
vesicles of  the hemispheres (so-called) are sym-
metrically disposed,  and lie one at each side of
the median axis of the primitive brain structure.
    The arrow in Fig.  I  points to the aperture
leading from the anterior cerebral vesicle  to the
laterally situated vesicle of the hemisphere—the
fore-brain.  The names  given by Carl V. Baer
to the  various parts of  the brain are most ap-
propriate.  We distinguish (Fig.  i) the transition
from  the spinal cord into the after-brain' (me-
dulla oblongata) ;  next the hind-brain (H. cere-
bellum), which the roof of  the  fourth ventricle
joins to the posterior wall of the ventricle  of the
after-brain.   The  mid-brain (Jl. corpora  quad-
  V
Ion
      Prosencepha-
     (fore-brain ;
Vorderhirn). Z.
Thai am encephalon
('Tween-brain; Zwis-
chenhirn).  Y. Fora-
men between  median
and r. lateral ventri-
cle. M. Mesenceph-
alon (M id-b rain;
Mitlelhim).  H. Ep-
encephalon.  (Hind-
brain ; Hinterhirn.)
N.  Metencephalon.
(After-brain; Nachh-
irn.)  (Reichert.)
   1 The terms After-, Hind-, Mid-, Inter-, and Fore-brain are respectively synony-
mous with Met-, Ep-, Mes-, Thalam-, and Pros-encephalon.—S. 
2
Psychiatry.
  Fig.
Frontal As-
of  the inter-brain)
rigcmina) forms the summit of this structure.  A part of the pro-
sencephalic  vesicle lies  between the  mid-brain and the vesicle
of the hemisphere.  This part is termed the inter-brain, and corre-
sponds to the region of the optic thalamus (Z.).   The vesicles of
the hemispheres develop into the fore-brain (V.).
                Fig. 2  is intended to show what an insignificant
             part of the original brain mass the prosencephalon
             is.   (We descend  from the mid- and  inter-brain -to
             the fore-brain as by a series of steps.) In consequence
             of a sharp bend of the cerebral axis on an ideal trans-
             verse diameter,  the after-brain appears below  as  a
pect of a Fcetal posterior branch of this  curved arc.   A horizontal
RXeic\e\t.a^ter section of the brain (Fig. 3.)'  shows  the  originally
 V. Prosenceph- lens-shaped convex outer surface of  the  fore-brain
bamencepha- (Fig- 3. v0> at a later stage of development.   This
Ion.  M. Mesen- originally convex surface of the fore-brain (which at
cephalon.   N.   °    :
Metencephalon. this stage  overlaps about  halt
shows, midway between its anterior and pos-
terior end, a trough-shaped depression.  This
depression is the first indication  of the fossa
Sylvii (S.).
    It is to be  noticed that the  walls  of the
vesicles of the hemispheres have increased in
thickness toward  the median line at  the ex-
pense of the lateral ventricles  {a. p.); as  a
result of  this growth we find the ganglionic
region, which, later  on,  divides  into the
caudate   and   lenticular  nuclei  protruding
between  the anterior and posterior horns.
    Corresponding to  this  thickening of sub-
stance  toward the  median  line, the outer
surface remains relatively undeveloped.   On
the   other hand,  the  anterior and  posterior
portions of the rudimentary hemispheres do
not   form any ganglionic  masses on  their
inner surface,  but develop mainly into cor-
tical and  medullary  substance,  deposited
upon their outer surfaces.  The intervening
portion  (S.) sinks  in, and thus  forms the
Sylvian  fossa.  The surface which presents
in this fossa is the  island  of Reil.
  Horizontal Section of
Fcetal Brain ; After His.
  VV. Fore-brain.  a.
Anterior horn.  p. Pos-
terior horn of the lateral
ventricle.   S.  Fossa
Sylvii, the outer surface
of the ganglionic region
of the fore-brain.  Z.
Inter-brain.
  m.  3d Ventricle.  Be-
hind  this, a part of the
mid-brain, surrounding
the  Aq.  Sylvii.'   The
posterior   boundary  of
the  mid - brain is ex-
plained by reference to
the  pari eta  flexure
(Fig. 4.)
1 This figure must be inverted when compared with Fig. 5, p. 4. 
Convex Surface of the Brain.                 3
    At this level the student may note how in the fore-brain the anterior (a.) and pos-
terior (p.) horns of the lateral ventricles open widely into the hollow of the primary
cerebral vesicle.  At this point  the median wall  of the prosencephalon  encircles this
opening.  The outer wall of the prosencephalon has given rise mid-way to the fossa
Sylvii.  The inner wall closes in upon the cerebral ventricle.  The fornix ascending
from  the cornu ammonis between S. and  Z., regions corresponding to  the corpus
striatum and the  thalamus opticus, constitutes the posterior portion of the median
wall.   The superior convex arch of the fornix is flattened down,  but  the descend-
ing portion of the fornix is enclosed within the front wall  of the anterior cerebral
vesicle.
    The fornix bounds the hollow separating the fore- and inter-brain, which cavity is
rendered cleft-shaped by the inward growth of the thalamus, and forever after remains
broadest at its anterior end (foramen Monroi).
    The upper wall of the thalamencephalon consists simply of
the membranous roof of the third ventricle, which passes to the
edge of an arch-shaped constriction arising from the upper and
anterior wall of the thalamencephalon. This constriction repre-
sents the fimbria of the  fornix.  The middle choroid plexus
of the upper wall is continued through the foramen Monroi into
the plexus of  the lateral ventricles.   The fornix in reality
limits  the extent  of the  fore-brain.  As soon as the  septum
and the corpus callosum are developed, the gyrus fornicatus ap-   View of the Convex
pears to be a limiting formation, or at least a secondary free Surface  of  a  fcetal
margin of the cerebral cortex. An examination of Fig. 3 shows Brain.
that the outer cerebral wall growing from the fossa Sylvii tow- p      S   1     7*
aid the median line gives rise  to the ganglia of the prosen- Thalamenceph.   M.
cephalon and encroaches upon the annularopening in the median Mesenceph.  H.
wall  and thus fills in the once copious hollow of  the ventricle. Epenceph.   N.  Met-
    '            .  ,                   ,.      , •  ,•     enceph. Beneath the
     The prosencephalon continues to extend in a postenordirec- ixo^[^ portion of the
tion at later stages of development ; we find, therefore, on  hori- prosencephalon   lies
zontal sections, that the corpus striatum and thalamus  opticus the olfactory lobe.
are juxtaposed from the  outside inwardly instead of lying one   (Lettering as in
            ,                                            Fig. I.J
behind the other.

     The  succession  of the three cerebral vesicles is marked  by
several flexions on the axis of the original medullary tube  (Fig. 4).
 The cervical flexure (convex posteriorly) marks the transition from
 the spinal cord to the metencephalon ; the frontal flexure (convex
 anteriorly), the transition from the metencephalon to the epenceph-
alon  ;  and   beneath  the  mesencephalon the  parietal flexure is
 formed.  The chorda dorsalis  terminates in the sinus formed by
the  last-named flexure.


        A.—THE PROSENCEPHALON (FORE-BRAIN).

                            convex  surface.

     The prosencephalon describes a curve about the Sylvian fossa
which was formed by the insufficient increase  in thickness  of  the 
4
Psychiatry.
outer  surface.   The upper portion  of this curve  is  the frontal
end of the prosencephalon, the lower portion is its temporal endf
while its summit represents the occipital region.  On account of the
insertion of the parietal region between the frontal and occipital
portions of the brain, the upper arm  of the arc is the longer one.
   The island of Reil Fig. 4, S., is connected with a protuberance
                                      (the  olfactory  lobe)   situ-
                                      ated on the lower aspect of
                                      the  frontal portion  of  the
                                      fore-brain.   Behind  the ol-
                                      factory  lobe,  the thalamen-
                                      cephalon  is  visible  in  the
                                      shape  of a basal protuber-
                                      ance which forms the region
                                      of the infundibulum on the
                                      anterior border of the parie-
                                      tal flexure.
                                         Let  us  now proceed to
                                      examine with  the  aid  of
                                      sections of the adult brain,
                                      the island of Reil—the floor
                                      of  the  Sylvian  fossa.    A
                                      horizontal  longitudinal sec-
                                      tion (Fig. 5), as well as a ver-
                                      tical   frontal  cross-section
                                      (Fig. 6)  of the brain  will
                                      serve  our purpose.   A nar-
                                      row passage,  the  Sylvian
                                      fissure (FS.), screens  from
                                      view the sac-like dilatation
                                      of  the  fossa Sylvii in  the
                                      furthest recess of which lies
                                      the island of Reil (J.).   The
                                      outer  walls of the  Sylvian
Horizontal Longitudinal Section from the Brain
        of Cercocebus Griseoviridis.
  F. Frontal end. O. Occipital end, of fore-brain.
A. Cornu ammonis.  R. Cortex.  M. Medullary  r^„„„  , u:„i,
substance.  L Island of Reil.   FS. Fissura Svl-  f°SSa> whlch  are wanting ill
Fi<
4, are  formed  by  the
       thickening   of
                on  the
vii.  V. Anterior horn.  Vp. Posterior horn of
the lateral ventricle (prosencephalic cavity).  T.    "~\.  "  ,
Corp. callosum.  S. Septum.  Nc. Na. Nucleus  Continued
caudatus  and L.1, L.a Nucleus lenticularis (the  cerebral  Substance
ganglia of the fore-brain). Cp.e. Capsula externa.
i.e., The medullary substance immediatelyadjoin-  Convex surface  of the pros
ing the lenticular nucleus.   To the outside of
the capsule lies the claustrum, and  next to this
the thin medullary substance of the island.- Ca.
encephalic  arch,  until  the
edges of this arch approach 
Convex Surface of the Brain.
5
Commissura  anterior.  Th.  Thalamus opticus
(thalamencephalon).  Th'. Pulvinar of  the opt.
thalamus. Cm. Commissura media.  Qu. Mesen-
cephalon—(Corp.  quadrigemina).  Bs. Brach-
ium superius (of the upper corp. bigemina). Aq.
Aquceduct  Sylvii.  Gi. Corp.  genie, internum.
so nearly to each other as
to leave nothing but a nar-
row fissure (FS.),  between
them.  The prosencephalic
Ge. Corp. genie, ext.  T'. Tegmentum, lying in arch surrounding  the  fossa
front of the gray substance  surrounding the aq.  _ _  __       .   °.
Sylvii  developed  its  sub-
stance  mainly in a  lateral
direction toward  the  cranial
walls, whereas the region of
Sylvii. Cp.i. Anterior portion of the inner capsule
lying between the  caudate and lenticular nu-
clei.  P. Posterior portion of the inner capsule
between optic thalamus and lenticular nucleus,—
the origin of the fibres of the cruscerbri.   Om.
Projection system from occipital lobe to pulvinar
corp. genie, int. and ext., the inf. corp. bigemina f_he fossa S. itself increased in
(Bi).  and to the pedunculus.                 ., . ,    ■ ,   ,    1    •   „  „
v ;          v                          thickness by developing gan-
glia in a median direction toward the cerebral ventricle(Figs.5 and6).
    The fissure of  Sylvius is not a
simple  passage.   It  is  bounded
not only by two protruding lips,
the  operculum   above   and  the
upper temporal  convolution  be-
low (Fig. 6 external  to J.),  which
cover  in  Burdach's upper  and
lower fissures, but also by a front
and rear wall lying on either  side
of  the  island  and  lapping over
the front  and rear fissures of Bur-
dach,  which  are thus   vertical
branches  of  the upper fissure.
These clefts  are  reached  by  the
ascending anterior and  posterior
branches  of  the  Sylvian  fissure,
ramus adscendens anterior et pos-
terior fissurce Sylvii.  The anteri-
or  ascending limb lies behind  the
orbital surface of the frontal lobe,
the posterior in front of  the base
of the first temporal  convolution.
The two  ascending divisions of
the Sylvian  fissure bound  the
operculum.   In man the island of
Reil generally possesses six con-
              Fig. 6.
Frontal Cross-Section from  the Brain of
       Cercocebus  Griseoviridis.
  J. Island of Reil, covered/by the oper-
culum and the first temporal convolution.
Gf. Gyrus fornicatus.  Tb.  Corp. Callo-
sum.  Nc. Nucl. caud. Ve. Lateral ventri-
cle. VIII. Median ventricle.  Th. Thalam.
opt.  Fd.  Descending,  Fa.  Ascending
fornix.  St.i. Lower pedicle of the thala-
mus from the ansa peduncularis. II. Chi-
asma.  II.' A parallel bundle of fibres.
            Ca. Radiating fibres from
                               .  .   A. Amygdala.  ^^. »xoU.a.u.s ..„._., *.~..
volutions diverging superiorly in  temporal  region  to anterior commissure
the shaoe of a fan.   These COnvo-  L-!« L-3' L-3 Nucl- lenticularis. ans. ansa
        "          "             .     of lenticular nucleus. Ce. Capsula external
lutions are continuous above with  CI. Claustrum.  Tp. Temporal lobe. 
6
Psychiatry.
the  convolutions of the operculum, behind  and  below with  the
superior surface  of the first temporal  convolution  (Huschke).
Naturally enough these convolutions cannot be made out unless
the  entire brain-axis,  together with the  island of  Reil,  be  dis-
sected out from the surrounding mantle;  the eye then rests upon
the  median  surfaces of  the hemispheres, and upon  the  inner
surface of the convex hemispherical arch.
   The ascending divisions of the Sylvian fissure are not  as well
marked  on the convex surface of  the human brain, and still  less
on that of the monkey, as they are in the brains of  the carnivora
(Fig. 7).  Among the  last  named this peculiarity  of configura-
tion is most distinct  (Fig. 7).    In the  brain of the bear  we
External Aspect of a Bear's Brain.
  Fr. Occ. Tm. Frontal, occipital, and temporal end.  Olf. Olfactory lobe.  Unc.
Uncus.  Cbl. Cerebellum.  Obi.  Medulla oblongata.  <#.§., |la. $lp. Sylvian fissure,
anterior and posterior ascending limbs.  C. Central fissure.  SI.1 Parallel fissure.  §l.a
Interparietal fissure.  A. Region of the anterior, P. Region of the posterior, central
convolution.  Arc. I., Arc.  II. Lower  and upper parietal arches.  L.1, L.a Inferior
parietal convolutions.  L.3  Superior parietal lobe.  L.1, L.2, L.3 Temporal convolu-
tions.  Fus. Gyrus fusiformis.
can  easily distinguish :  a blunt lower end of the  operculum (near
if. 15.), a highly developed a?itcrior ascending (|la.), and a  long pos-
terior ascending, division  (iljj.)  of the Sylvian fissure.  Similarly
both the  ascending branches are exquisitely distinct on the basal
surface of the  brain  of Mustela (Fig. 10, right).   The Sylvian
fissure, which, in this instance screens from  view an exceedingly
rudimentary island, lies immediately adjoining to the lobus olfacto-
rius (Ge.) throughout the entire length of the operculum, as was
the case with the human brain represented in Fig. 4.  In the rudi-
mentary olfactory lobe of adult man, this external olfactory con- 
Convex Surface of the Brain.
7
volution  (Fig. 15 Ge., Fig. 18) is replaced by the external white
medullary strand of the trigonum olfactorium.
    In addition to the fossa Sylvii which is present in all mamma-
lian brains, and is often the only fossa present, we must now con-
sider the typical fissures of more highly developed brains ;  these
sulci mark out the  various regions, or, at least, the convolutions
of  the convex surface  of the fore-brain,  and serve as our guides
over this area.   Apart from  its morphological value, a thorough
knowledge of these fissures and convolutions  is absolutely  indis-
pensable to a proper appreciation of the physiological experiments
performed on the animal brain.
    If the " type " has been made out clearly enough to  enable us
to  determine the identical regions  of the  mammalian and the
human  brain, then  the important conclusions from physiologi-
cal  experiment and from pathological anatomy  may  safely be
compared one with  the other.
    We  find  typical fissures in  the human fcetal brain, from the
sixth month of its development  on.
    I have not had  the opportunity of making any detailed  inde-
pendent  study  of  the
human   fcetal  brain.
My description is based
upon  a  study of the
monkey's  brain.    In
some  slight  degree  I
am  justified  in  taking
such a  course by the
saying of  v. Bischoff,
that the monkey brain
is  not   a  miniature
model of  the  human
brain, but that the for-
rn-rrenrpcenrq arrested   Fr.  rrontai ena.
mer represents arrested 0ccipital end. gu inferior frontal
stages in the fcetal de-
         Tm.
             Fig 8.
       Brain of Hamadryas.
Frontal end.
                                           Tm.  Temporal end.  Occ,
                                                          gl.a Rudi-
                        mentary superior frontal fissure.  p(£. Anterior radial
  .°         f  1    1  ,  fissure (sulc. praecentralis).   rC Ecker's interparietal
VClopment Ot tne  lat- fissure (postenor radial fissure).   |.S. Fissura Sylvii.
ter.   In  the brain  of $P-  Ramus ascendens posterior.  SI.1 First  temporal
   '      1     .     . ^   fiss.  (sulcus parallel.) §. occ. i. External occipital fissure
the monkey tliere  IS a (primate ape fissure), arc. occ. Occipital lobe. (The
verv  distinct  median  vertical fissure might answer to the interoccipital fissure
   \               .  ' of man, and the horizontal fissure  might mark Ecker's
radiating  furrow (£.), gyrus  occipitalis,  arc.   II.  Superior parietal arch.
cnlm* rentralis  or  fis- arc-  L Inf' pariet. arch.   L.1, L.2, L.3 First, second,
SU1CUS cen iraub, ui  us  and  third temporal convoiutions.  gp. 0. Sulcus praeoc-
SUre of  Rolando. The cipitalis.   Cbl. Cerebellum.  Obi. Med. oblongata. 
8
Psychiatry.
radiating,  primary fissures diverge toward the upper border of the
hemispherical arch,  and  converge toward  its  lower border, i.  e.,
toward  the operculum.   In  front  of the  sulcus Rolando,  mark-
ing  the  posterior  boundary of  the  frontal lobe,  lies the ante-
rior median  furrow,  the  sulcus prcecentralis,  " transverse  frontal
fissure,"  (Fig. 8, pd).   This sulcus  praecentralis combines  with
the  straight  inferior frontal  fissure (SI.1)  to  form a cross-bow.
Convexity of the Human Brain.
    J. Island of Reil. <df.S. Sylvian fissure. The letters are placed on the temporal lip
of the fissure ; above the island lies the operculum, bounded by the anterior ascending
limb, which passes upward toward the letters  SI.1 and the posterior ascending limb
approaching the lettering arc I.  €. central fissure.  pC. prsecentral fissure (anterior
radial fissure).   t.€. (S.op.) post-radial fissure  (sulcus occipito-parietalis).   S.ncc. Oc-
cipital fissure. SI.1 SI.2 Longitudinal fissures in frontal and temporal lobes. SI.1 desig-
nates, below, parallel 'fissure. S.po. Prae-occipital fissure. Fus. Gyrus fusiformis. Ca.
Anterior central convolutions.  Cp. Posterior central convolutions.   Ps. (Qu.) Superior
parietal lobe (lobus quadratus.).  Arc. I., arc II.  Inferior and superior parietal con-
volutions. S. etc. t. External occipital fissure (ape fissure). Cu. Occ, Occ. i.  The three
occipital convolutions of Ecker, Cu. indicating the convex surface of the cuneus, and
Occ i. designating the convex surface of the gyrus lingualis.  Gl. cm. Callosomarginal
convolution.  Arc. occ. Occipital  arch.  L.1,  L.2, L.3, above <f.S.  Frontal  con-
volutions.1
The sulcus  praecentralis represents  the bow, the  fissure §1.' the

arrow.   Behind the sulcus centralis lies the posterior radial fissure

(r(L) which  diagonally divides  the  almost quadrilateral  parietal

lobe (lobus parietalis) into an inferior and  superior parietal lobule.

For this reason Ecker has proposed the name Interparietal fissure.

The lobus  parietalis  of the monkey is bounded in front by the

     1 The frontal convolutions are  numbered from below upward.  Meynert's first
F. convolution is the same as Broca's Third F. conv.—S. 
Convex Surface of the Brain.                9
sulcus centralis, above  by  the border of the hemispherical arch,
below by the fissura Sylvii, posteriorly by  the  external occipital
fissure which is most highly developed in the  lower apes.  This
" ape  fissure "(Fig.  8 gs. occ. z.) lies behind the radial furrows.
    This fissure, which is less marked even in the higher forms of apes, is at times
distinctly developed, at times scarcely recognizable, in the brain of man. But the most
rudimentary form of it must be classed among the " typical"  fissures. This  fissure lies
immediately adjoining to the posterior border of the second parietal arch.  The anterior
edge of the fissure protrudes,  sword-like, beyond the posterior margin of the parietal
lobe, only, however, in the lower orders of apes.  This boundary line is also termed
the operculum lobi occipitalis.   In the higher  apes these relations are more like those
in man.
    According to Reichert's opinion, which  we accept, the parallel
fissure (Fig. 8, §1.'), lying between the first and
the second  temporal   convolutions, must  be
added to the  list of primary radial  furrows.
With Reichert, we  may term this the inferior
radialfissure.  On separating the lips of this fis-
sure, we notice that it winds around the fissura
Sylvii toward the edge of the operculum, so that
all four  primary radial  fissures converge toward
the superior border of the Sylvian fissure.
    Having  given  this  (true)  diagrammatic
account of the surface of the monkey's brain,
we will proceed to describe the various  divis-
ions of  the fore-brain in man, the monkey, and
in carnivora.
    1. The Frontal Lobe  reaches  a high stage  endTrT,X'°TnePas!
of development in  man.   After dissecting  out  cending branches of the
 ,,         ,.       1  .1    • 1   j  -i.      i-i.  i.   Sylvian fissure, the mid-
the  ganglion and the island,  it  constitutes  dfe part of which  lies
41-42$ of the remaining hemispherical sub-  next  to  the  olfactory
          , ..   .   .       .      . ,     .       _.  convolution (Ge.).  Ge.
stance,  while in the monkey and bear but 35^  lod. 0lf.  La. Region of
and   30 %  respectively  can be  put  to  the  the  an'erlor. ethmoid
       °   '      r        111     tii      plate. II.  Chiasma opti-
account of the  frontal lobe.   In  the  lower  Cum. J. M.  Infundibu-
 primates (Fig. 8), possessing a sulcus centralis,  [um  anpVTedu3us'
 but no well-defined central convolution, the  sul-  cerebri. V. Pons Varo-
cus praecentralis may be taken as an indication
of said convolution. On the other hand, the  sul-
    Fig. 10.
 Brain of Mustela.
Fr., Tm„ Occ. Fron-
                                                Corp.rhomboideum.Cbl.
                                                Cerebellum.  Gf. Gyrus
cus praecentralis (p. C.) clearly defines the boun- dak"*!^ L.2' Inferior
daries of the anterior central convolution (Fig. convolution  passing
                                         111   from the parietal lobe to
9, Ca.) of man.   lhat part of the frontal lobe the temporal lobe around
lying  in  front  of the radial fissures is exces- Jhe  posterior ascending
 J  o                                    .      branch  of the Sylvian
sively developed.  In  front of  the radial or fissure. 
IO
Psychiatry.
perpendicular fissures there  are two more  typical longitudinal
fissures.  The inferior longitudinal fissure  (iL1) bounds  an arch-
shaped convolution  (gyrus transitorius) which surrounds the  as-
cending anterior division of the Sylvian fissure.  The gyrus trans-
itorius, emanating  from the  convex convolution  in front of the
operculum, passes on  to  the orbital surface of the frontal  lobe
(Fig. 9, forward of I.).  The inferior border of this convolution is
contiguous with that portion of  the  orbital  surface lying to the
outside of  the olfactory  lobe,  and to  which (in  lower  forms of
mammals) Leuret applied the name gyrus orbitalis.  Thus we find
in the brain of a bear the anterior margin of  the operculum bend-
ing over and passing into a convolution which, circumventing the
ramus adsc.  anter.  fissurae Sylvii, extends  also to the orbital sur-
face, and there lies to the outside  of the lobus olfactorius (near |h.).
The frontal lobe of the bear is thus characterized by a gyrus tran-
sitorius homologous to the frontal lobe of man.  The large frontal
lobe of the human  brain bears  a second  longitudinal sulcus ($I.2),
which, surrounding the inferior longitudinal fissure concentrically,
gives rise to two superior longitudinal frontal convolutions (Fig. 9,
L.2, L.3).  Like the gyrus transitorius, these  convolutions pass from
the convexity to the orbital surface of the  brain.
    On the  basal surface of the brain of Mustcla, it is also evident
that the cortical substance of the operculum (between Ala. and Ge.,
Fig. 10), winding around the anterior ascending branch (2la.), finally
attains to the orbital  surface, at the  outside of the lobus olfac-
torius.
    According to the  above account,  the  frontal lobe  of the
human brain possesses four principal fissures: two perpendicular,
i. e., the central and prae-central fissures ; two longitudinal fissures
(an inferior and  superior arch-shaped fissure); furthermore, four
typical primary  convolutions.  These  are :  (1) The anterior cen-
tral ; (2)  lower; (3) middle ;  (4) upper longitudinal, convolutions.

    That the  convolutions of the frontal lobe are not at all times and everywhere as
distinctly defined on the surface of the brain as they are by the prominent  lines on the
accompanying cut (Fig. 9) is due, first, to the formation of anastomoses which connect
parts originally separate, by bridging over primary (" typical") fissures ; secondly, to the
so-called secondary and  tertiary  fissures,  which interrupt the primarily contiguous
convolutions, and which,  when surrounded by cortical substance, give rise to " insular "
formations.  The anastomoses, as well as the secondary fissures,  are in the human
brain  an indication of the greater development of cortical substance.  Thirdly, we
find   the  primary  convolution type obscured by serpentine intricacy  of form,
by the formation of ansae.  Finally, all three extremes of cortical development 
                 Convex Surface of the Brain.               11

may exert their influences over proximate portions of the brain. Distinctness of type is
by no means identical with paucity of convolutions.  Wealth of convolutions is more
characteristic of the human brain, as  com-
pared with the brain of  monkeys and of
carnivora, than when compared with the
brains of herbivora and cetaceans.  Conse-
quently the superiority of the  human  cere-
bral  surface must not be  attributed exclu-
sively to the wealth of convolutions.

    The orbital surface of the fron-
tal  lobe  of man's brain bears in
its typical form close resemblance
to that of the primates (Figs. 13
and 11).   To  be sure, we find in
man the  sulcus  rectus,  in which
the olfactory bulb  is  imbedded
(Figs.  11 and  18, Olf.), and which
is wanting in the monkey's brain.
But for the very reason that  it is
wanting  in the  monkey, in spite
of a more highly developed olfac-
tory lobe,  the sulcus rectus  can
not be claimed to be destined to
serve   as a lodging-place  for  the
lobus olfactorius.
    The sulcus rectus brings about
the division  of  the third frontal
convolution into two parallel con-
volutions.  This tendency toward
a division of the terminal convolu-
tion is often,  though less clearly,
indicated in  the formation of secondary fissures on the convex
surface of  the  hemispheres (Fig. 9, L.3).   Externally from the
straight fissure lies the sulcus  cruciatus which  might be more ap-
propriately termed the H-shaped fissure.  This typical formation is
well represented in the basal  aspect of the primate brain (Fig. 11,
3. ex.) and  on the shaded surface  of Fig. 13.   The  transverse fis-
sure of the H causes an inflection of  the middle frontal convolu-
tion.   This transverse fissure  may be absent in the primate  brain.
In that case four frontal convolutions lie next to one another.
    The H-shaped fissure with its many variations presents the most instructive ex-
ample of a great dissimilarity  of forms, whose origin from the original type is yet
     Fig.  II.
Brain of Hamadryas.
  Fr., Tin., Occ. Frontal, temporal, oc-
cipital end. Olf. Olfactory lobe.  S. tr.
Sulcus cruciatus.  Jf.S.  Fissura Sylvii.
SI.1, SI.2 First and second temporal fis-
sures.  L.1, L.a,  L.3 Temporal convol-
utions. Gf. Gyrus fornicatus. A. Amyg-
dala.   S-  po. Praeocciptal fissure.  II.
Optic chiasm.  J.  Infundibulum.  M.
Corpora mamillaria. L. Lamina perfor.
post.    Pd.  Pedunculus cerebri.   V.
pons.   P.  Pyramid.   Rh.   Corpus
rhomboideum. O. Inferior olivary body.
R. Restiform body. Cbl.  Cerebellum.
M. Spinal cord. 
12
Psychiatry.
 quite distinct.  The transverse fissure of the H  causes, as it were, an inflection of
 the middle longitudinal convolution.  At times an anastomosis of the median third
 with the  lateral first longitudinal convolution of the orbital surface crosses the trans-
 verse fissure in a median-exterior direction, thus uniting primarily (typically) separ-
 ate convolutions.  And then again the transverse fissure may be bridged over by an
 anastomosis uniting the portions of the middle convolution situated anteriorly and
 posteriorly, respectively, of  the transverse  fissure.   In the  last instance the  H is
 resolved into three straight convolutions, which lie to the outside of the sulcus rectus
 parallel to the now created innermost  fourth straight orbital convolution.  Anasto-
 moses have, therefore,  in the above-mentioned instances, given rise to different divi-
 sions of the orbital surface.  These two kinds of changes come entirely within the
 scope of  the typical cortical complications mentioned  above.  Such  changes result
 from the  union of parts (originally) typically separate.  Complications in the develop-
 ment of convolutions may turn the H-shaped into a star-shaped formation. Secondary
 fissures of the orbital surface are rarely wanting in man.
    The third  surface  of the  frontal  lobe—the  median—will be
 described together with  the entire median surface (Fig.  13, p. 19).
    2. The  Parietal Lobe.   The  study of  the parietal  lobe of the
 primate brain  (Fig. 8)  is indispensable  to  a proper understanding
 of the convex surface of the parietal lobe in man.   The anterior
 boundary  of the  parietal lobe  is  formed  by the sulcus centralis ;
 consequently  the  posterior  central convolution is the frontmost
 convolution of this lobe.  In  man, also,  there lies behind the sulcus
 centralis (Fig. 9)  a posterior radial fissure—the sulcus interparie-
 talis—which, extending  quite  up to the superior border of  the
 hemisphere, diagonally divides the parietal region [|lc. (JS.op.) |lc.].
 The posterior radial fissure differs from  the sulcus interparietalis of
 the  monkey in  this: that  instead of  terminating at  the sulcus
 occipitalis  it passes  beyond it, in order,  further on,  to  form  the
 interoccipital fissure (Fig. 9, S.op.).  Because of  its transition into
 the  occipital convolutions,  the  posterior  limit of the superior
 parietal lobule is  often  indistinctly defined.  The  entire fissure
 (interparieto-occipitalis)  bounds the arch-shaped parietal and oc-
 cipital formations  of  the  cortex.
    The second " typical"  line  of demarcation of  the  parietal
 lobe is the posterior  ascending limb of  the Sylvian fissure ;  the
 third is  the parietal portion of the parallel fissure.
    The superior parietal lobe of man is frequently connected with the  inferior lobe
by means of a vertical anastomosis.   There results a long vertical fissure behind the
post central convolution (cp.) which, if care be not taken to discriminate between them,
may be mistaken for the fissure of Rolando.
   The  superior  parietal  convolutions  form a triangular lobe
whose  base  is situated  superiorly.   The superior parietal lobe
[lobus parietalis superior.  (Huschke)] is the external surface of the 
                Convex Surface of the Brain.             13

lobus  quadratus, the  praecuneus  of  the median surface—from
which it takes  its name.  Fig. 9, Ps., Qu.
   The  inferior parietal lobe  (lobus parietalis inferior., lobulus
tuberis, Huschke) starts often from the posterior central convolu-
tion as a simple gyrus; often, too, this mode of origin becomes com-
plex.  Below the interparietal fissure and  in  front of the posterior
branch of the Sylvian fissure (Figs. 8 and 9), the inferior  parietal
convolution divides, as in primates, into  two arch-shaped  convo-
lutions (v.  Bischoff).  The  anterior (properly  speaking) inferior
parietal arch (Figs. 8 and 9, arc. I.) surrounds the posterior ascend-
ing limb of the Sylvian fissure and is contiguous with the superior
temporal convolution.  In addition to this, the inferior parietal
lobe  develops  a second (posterior) superior parietal arch (arc. II.)
surrounding the parallel fissure, which arch is continued  into the
second temporal convolution, back of that fissure.
    The posterior boundary  of the second parietal arch is  formed
by a Assure which is at times distinctly developed, and at other
times  interrupted (shortened)  by anastomoses connecting the
second parietal arch  with the  occipital  lobe.  This  fissure is the
 external occipital fissure of man—the rudimentary ape fissure (Fig.
 9, §. 0CC. t.).
    Comparison with the brain of a primate  impresses more firmly
 upon one's mind the " typical " lines of the parietal  lobe in man.
 In both we find an anterior boundary defined by the sulcus cen-
 tralis, a superior margin by the convex border of the hemispherical
 arch, extending from the sulcus centralis to the incision  of the
 internal occipital fissure ;  an inferior border formed by the pos-
 terior  half and the  posterior ascending branch of the  Sylvian
 fisssure and lastly, a  posterior boundary, marked by the external
 occipital fissure, i. c., by the fissure surrounding the second  parietal
 arch (Fig.  8, £. occ. t.).
    The double arch-shaped formations—the parietal  arches—of
 the  monkey's brain, connecting the lower parietal convolution
 with the two  superior temporal convolutions, furnish the key-
 note to the understanding of  the identical parts  of the human
 brain.   There is a certain diagrammatic  simplicity about the man-
 ner in  which the arcus I.  of the monkey passes around  the pos-
 terior ascending limb of the fiss. S. into the first temporal convo-
 lution ; and in equally diagrammatic fashion the arcus II. passes
 around the vertex of the parallel fissure at  the  superior border of
 the  second parietal convolution, in order to descend in  the 
H
Psychiatry.
direction of  the parallel fissure as  the second  temporal convo-
ution.
    Not invariably, yet often enough, the first parietal convolution of man is bounded
by a fissure (Fig. 9, over arc I.).  This fissure, though generally shallow, is certainly
" typical," as is evident on the parietal convolutions of carnivora. There are undoubted
exceptions to  Pansch's rule, that the typical fissures of the brains are the deepest.
Furthermore,  as seen in Fig. 9, the superior border of  the first parietal convolution
not infrequently anastomoses with the inferior (concave) border of the second parietal
convolution (vertical convolution between arc. I. and arc. II.).  This is a typical con-
volution not of the monkey, but of the cat.
    The cat  possesses several  vertical  anastomosing convolutions.  They seem to
indicate the restriction of development of the convolutions in a longitudinal direction,
due to the brachycephalic skull of the cat.  The mechanical laws underlying the
development of convolutions have been stated as perfectly as the present state of our
knowledge would permit by Wundt, Henle, L. Meyer, and the author.
    The convex surfaces  of the parietal  lobes of  the monkey and
of man  exhibit four convolutions :  1.  The posterior central  con-
volution.   2. The lobus  parietalis superior  (lobus  quadratus,
praecuneus)—complicated in man, frequently connecting with the
post, centr. convolution.  3.  The inferior  parietal  arch.   4.  The
superior parietal arch, generally emanating from a single root of
the inferior parietal convolution.  The posterior central convolu-
tion  and the anterior segment of the inferior parietal arch  take
part  in the formation of the operculum.
    3. The Occipital Lobe.   The occipital lobe in the lower forms
of primates may  present  an  entirely  smooth  surface.   Fig.  9
shows two fissures at right angles to one  another.  The vertical
fissures may possibly be a rudimentary homologon of the  sulcus
interoccipitalis  in  man,  and the  horizontal fissure may  represent
those straight fissures which bound Ecker's occipital convolutions,
of which mention will be made later on.
    The sulcus  interoccipitalis (^.op.),  the continuation  of the
fissura interparietalis, divides  the occipital lobe  of man into  an
inferior (anterior)  and a superior (posterior) cortical area.   The
anterior portion of the  occipital lobe is  arch-shaped  in typical
brains.   The arcus occipitalis (Fig. 9, arc. occ),  the third  arch
(according  to Bischoff), back of  the  central  fissure,  possesses
a depression which I am disposed to regard as the occipital origin
of the second temporal fissure (Fig. 9, §1.'), reaching as high up as
the origin  of the first temporal fissure—the fissura parallelis.
    This fissure,  the lumen  of  the arcus occipitalis,  wends  its
way toward  the  second  longitudinal  fissure  of  the  temporal
lobe, which is  generally most distinct anteriorly between the 
Convex Surface of the Brain.             15
■second and  third  temporal  convolutions (L.a  L.3),  just as the
parallel fissure can be best made out between the first and second
temporal convolutions (L.1  L.2).  Just as the  posterior branch
of  the first  and second  parietal arches  passes  into  and con-
nects with the  first  and  second temporal convolutions, so the
posterior portion of the  arcus  occipitalis  passes  into  the  third
temporal convolution.  But the continuity of this fissure, behind
which the third temporal convolution arises from the  occipital
arch, is  interrupted by anastomoses, which pass from  the  third
temporal convolution, from the  vertex  of  the  occipital  lobe,
and finally from the gyrus fusifor mis, to the second temporal con-
volution. As in the monkey, so in man, we may often be able to
trace among the anastomoses of the second temporal convolution a
deep fissure  (sulcus praeoccipitalis—Fig. 9, ^.po.), the continuation
of the inferior margin of the occipital vertex.  These vertical anas-
tomoses divide both the second temporal (§l.a) and the third tem-
poral  convolutions into a superior and an  inferior portion.  It is
only in  the  anterior region of  the temporal lobe that the two
fissures and  the three convolutions are distinctly developed.
    Above the  occipital arch the  external marginal convolution
continues the superior parietal lobule from the sulcus occipitalis
internus  downward.    Ecker describes three occipital  convolu-
tions lying  one above the other.  The two lower convolutions
pass in a horizontal direction from the occipital lobe  to the front
(Occ. and Occ. i.).  The superior occipital convolution is the ex-
ternal surface of the cuneus, separated from the  superior  parietal
convolution  by the occipital fissure (superior occipital  lobule of
Huschke).   The second and third occipital  convolutions consti-
tute the convex surface of the  gyrus  glossiformis, which, on the
median aspect,  is situated  below the sulcus calcarinus.  The third
straight occipital convolution, in passing to the front, touches
with its inferior margin upon the prasoccipital fissure (Fig. 8, S». po.),
of which v. Bischoff and Wernicke make mention.
    The human  occipital lobe is triangular  in shape; anteriorly it
is imperfect, bounded generally by the fissura occipitalis interna,
the irregular opening of a convolution of the convexity.   In Fig.
9, &. occ, the  lower portion of such a loop is screened by the sulcus
interoccipitalis.  This ansa may descend a long distance, and yet will
prevent the  fusion of the external and internal  occipital fissures.
An  ape-fissure,  extending  to  the margin of  the  hemisphere,
(W. Sander) will, therefore, be less frequent than appearances would 
i6
Psychiatry.
 lead one to believe.   The margin of the hemisphere  forms the
 superior boundary of  the  occipital  lobe;  there  is no natural
 inferior boundary, however, between the  occipital  and temporal
 lobes.   An artificial boundary between the convex surfaces  of the
 temporal lobe on the  one  side, and the parietal  and  occipital
 lobes on the other, might be denoted by a line passing from the
 lowest  point, of the posterior ascending limb of the Sylvian fissure,
 to the  lowest portion  of the sulcus prceoccipitalis.
    The surface of the occipital  lobe  is marked by  the  following
 fissures:  I,  the  sulcus interoccipitalis;  2, the beginning of the
 second  temporal fissure;   3,  the fissure  between  the first and
 second convolutions of  Ecker;  4, the fissure between the second
 and  third  convolutions of  Ecker.  The  occipital  lobe  of man
 presents on its   convexity  four  convolutions:   1,  the  arcus
 occipitalis; 2, 3, and 4, the three convolutions of Ecker.
    4. The Temporal Lobe.   Its superior  surface borders upon the
 island  of Reil; its superior margin  touches the operculum.   The
 inferior margin is continued, by means of  a free, arched, anterior
 margin, into the  superior.   Posteriorly the temporal lobe is con-
 tiguous with the  parietal and  occipital lobes  along the  artificial
 boundary line  mentioned  above.  The temporal lobe  exhibits
 three typical furrows:   I,  the  superior  longitudinal sulcus—
 sulcus parallelis;  2, the inferior longitudinal sulcus ; 3, the sulcus
 praeoccipitalis.   The first of these sulci is  rarely interrupted ; the
 second, invariably so.  The convolutions of the temporal lobe are:
 1, the superior ; 2, the middle;  3, the inferior longitudinal convo-
 lutions (L.1  L.a L.3), 4 variable vertical convolutions anastomosing
 with the second longitudinal convolution.

    For the understanding of the facts gleaned from experimental physiology we must
 needs rely upon our knowledge of comparative anatomy. We are prompted,  therefore,
 to give in the following paragraphs  an account of the homologous parts in the brains of
 man, the  monkey, and the carnivora.
    In the brain of the bear (Fig. 7) the fissure  C. is,  beyond a doubt, the boundary
 line between the frontal and parietal lobes.  Characteristic of the frontal lobe are con-
 volutions  (in lower forms of  carnivora this portion of the cortical surface is smooth)
 which, arising from the anterior margin of the operculum, make a curve about  the an-
 terior ascending branch of the Sylvian fissure (Transitional convolution of Huschke's).
 The human frontal lobe possesses two additional longitudinal convolutions concentri-
 cally  surrounding the transitional convolution.  The type of the frontal lobe  in car-
 nivora and man is fixed and modified by the simple or intricate development of those
convolutions which form arches around the anterior  limb of the Sylvian fissure  and
pass on to  the orbital surface. The frontal lobe of  the bear contains still another
deep  sulcus, which separates  two longitudinal convolutions, and lies close and parallel 
Convex Surface of the Brain.                  ij
to the superior free margin.  In the figure this  sulcus is denoted by a faint line, for
the dark lines are to show at a glance the so-called primary fissures.
     The sulcus centralis of the bear passes obliquely upwards and backwards as in man
and the primates.  In the majority of carnivora,  however, the sulcus centralis assumes
a different shape, extending backward  quite to  the occipital margin.   In the  latter
cases the central  fissure gives  rise to the most external of the arched fissures  which
surround the post, ascend, limb of the Sylvian fissure.  This arch-shaped central  fissure
is lodged within the  superior  parieto-occipital  convolution.   No animal possesses a
regio centralis as  much akin to the central region of man as is that of the bear, and thi?
animal undoubtedly ranks highest in cerebral development.  In Fig. 7 (L.3) the tendency
to  the formation of arched extensions  of  the sulcus centralis is expressed merely by
insular, unconnected fissures.   In the same figure the arrangement of parts is obscured
by the insertion  of a convolution (behind C), which originates  on the median aspect,
but is not common to all bears. In front of the sulcus centralis (near A.) the bear shows
a prsecentral fissure much more marked than the  thin line of the figure would lead one
to  suppose.
     The arched  fissures  and arched convolutions,  which lend  a strange, non-human
appearance to the brains of carnivora, pass around the posterior ascending branch of the
Jissura Sylvii. The first  arched fissure  (Fig. 7, SI.1) which
surrounds the arc.  I. marks out a  parieto-occipital  convo-
lution, whose opening the Sylvian  fissure  is ;  this same
arched fissure divides the first and second convolutions as
the sulcus parallelis does  in man.   The former differs from
the human  parallel fissure in  sending  a long anterior
branch into the lobus parietalis.  The second arched fissure
(Fig. 7, SI.2) lies over the arc.  II. of the bear's brain. This   Fcetal Brain of a  Dog
          ,      i.i       • ■         • j •       -u  .-i.         (after Wilder).
corresponds exactly to the position occupied in man by the        J
posterior radial  fissure,  the  sulcus  interparietalis,  which   c-m-   Calloso-marginal
 j.  . ,    ,.    ,        . 1  1  1 n         ■      •  ,. 1  1  u 1   convolution.  ©If.  Olfac-
divides (in the parietal  lobe) a superior parietal  lobule  tQry ]obe    A Amygdaia,
from the two inferior parietal arches, which in turn connect  s;.  Sylvian fossa.  |Ea. Its
with the two temporal convolutions (L.1 L.2).              anterior ascending  limb.
     The fissure  in  question lying behind the fissura cen- P«- Parallel  fissure   «.
                1  .        • . 1    u      j  u. ji         Central fissure.  rC. Inter-
tralis, and over the two parietal arches, undoubtedly repre-   arietal fissure.
sents  the posterior central fissure.   In contradistinction to
man and the  primates this  fissure passes immediately into the second temporal  fissure
 This simple type is modified in man and the monkey by the  complicated structure of
the occipital lobe.
     The difference in the external aspect of the brains of man and the carnivora  is due,
 first, to the slight development in the latter of the frontal and occipital brain (the oc-
cipital brain not  overlapping the cerebellum) ;  and,  secondly to the enormous develop-
 ment of the parietal brain.  An unusual development of the frontal, of the occipital,
and of the parietal portions is characteristic respectively of the brain of  man, the
 primates,  and the  carnivora.   The most striking  feature  of the carnivora brain, as
compared with  the human  brain, is  undoubtedly the greater  development  of the
parietal portions of the arched fissures  and arched  convolutions.   The arched  convo-
lutions are very  distinct  owing to  an equal development of  both branches; in man,
methodical examination  alone reveals  them.  The  arched  posterior extension  of the
middle radial fissure (central)  adds to the  number of arches in  the carnivora.   The
primary position of the radial fissures of carnivora is well represented in the  adjoining
cut (Fig.  12), after Wilder, of a foetal dog.  In spite of its elongated shape, we can
readily discern a frontal,  a temporal, and an occipital region.  The anterior ascending 
i8
Psychiatry.
limb of the open Sylvian fissure is beautifully developed, showing distinctly the course
of the frontal end around this arch into the orbital surface of the frontal lobe, to the
outer side of the olfactory lobe.  This portion of the brain is bounded posteriorly by a
central fissure which, as was  the case in the bear, is surrounded on all sides by cortical
substance, is insulated from the rest of the cortex.  In the parietal region we discover a
very delicate longitudinal fissure, which, in the adult dog, combines with the fissura cen-
tralis to form a superior arched  fissure. Behind this sulcus centralis (an anterior radial
fissure is not visible) lies  a very marked fissure with two flat arches beneath it.
These wind about the Sylvian fissure and have not  yet extended to  the temporal
lobe.   These must  necessarily  be  taken to  be the  two parietal  arches.  The
fissure  separating both  arches  would, if continued backwards and  downwards,
bound a first temporal  arch.  This  corresponds, therefore, to the sulcus parallelis,
while  the deeper fissure  (before  mentioned)  which lies above both parietal arches
answers  to the  posterior central  fissure.  Continued  backwards, this fissure will, in
later stages  of  development, form the boundary of the arc. temp. II.  It separates,
furthermore, the region of  the superior parietal convolution from the inferior, which
gives rise to the two parietal arches.   We notice also in carnivora the rudiments of a.
posterior and an anterior arched fissure which  represent in the same succession the:
radial  fissures of man and the primates,
    No  reference need be  made to the fissure r.m.  I simply wish to remark that
of the  motor centres, of which we shall treat later on, Hitzig's  centre for the innerva-
tions of the muscles of the neck is located  in front of this sulcus.   For this reason the
motor centres are not limited morphologically to the sulcus centralis, about the posi-
tion of which Hitzig is in error.  The convolution of the dog's brain which he con-
siders  homologous with the anterior central convolution of the monkey, is  not the
anterior but  the posterior central convolution.

     THE  MEDIAN SURFACE  OF THE FORE-BRAIN,  AND  THE LOBUS
                             OLFACTORIUS.

    The cortical  duplications of  the  median surface of the hemi-
spheres are far simpler than those of the  convexity of  the brain  ;
but special formations, such as the  lobus olfactorius and the cornu
ammonis,  whose genetic bearings we must now study, complicate
this otherwise simple  surface.
    In  Fig.  I  we are supposed to look  within the  thin-walled
cerebral  vesicle, and   from  the  cavity  of the thalamencephalon
into  the small opening forming  the communication between the
prosencephalic  vesicle and the  third ventricle.   This opening,
whose anterior  inferior  portion  is transformed  later on  into the
foramen Monroi, must necessarily have annular boundaries.   This
ring, proportionately  enlarged, is discernible in the adult brain in
the shape  of the fimbria, and the descending  pillar of  the fornix
(Fig. 13, Fi.  d.)  The lateral wall  of the thalamencephalon prolifer-
ates  and forms the  thalamus opticus within this constriction-ring,
which  it  reduces to the arched cleft between the optic thalamus
and the fornix.   The separation of the vesicle of  the hemisphere 
Median Surface of the Brain.               19
starts from the upper  wall of  the anterior vesicle,  or, in other
words, from the superior and anterior walls of the thalamencepha-
lon.   This superior wall does not develop into nerve tissue, but
into  a membrane from which the plexus chorioidei are developed.
The  thinning  out  of this constriction-ring at the fimbria  gives
lasting evidence of  the transition of this  ring into  the  superior
membranous wall of  the thalamencephalon.
Median Aspect of the Human Brain.
   Fr., Occ,  Tm. Frontal, occipital, and temporal  end of the hemisphere.   Olf..
Olfactory lobe.  S.rr. Sulcus cruciatus. S.rat. Calloso-marginal sulcus.  S.occ. Internal
occipital fissure.  Sr. Calcarine fissure. S. @. ff. #. Superior occipitotemporal fissure.
S- ©. ®- i. Inferior occipito-temporal fissure.  SI.2 Second temporal longitudinal con-
volution. L.3 Median surface of the third frontal longitudinal convolution.  Gf. Gyrus
fornicatus.   Qu.  Lobus quadratus (praecuneus, superior parietal lobe).  Cuti. Cuneus,
superior occipital lobe.   Gl. Gyrus  glossiformis convolution of  Burdach's  internal
primary fasciculus.  Fus.  Gyrus fusiformis, convolution of Burdach's inferior longi-
tudinal fasciculus.   L.3 L.3 Temporal longitudinal convolutions.  Sub. Subiculum
cornu  ammonis.   Unc.  Uncus.  A.   Amygdala.  Fd.  Facia dentata  Tarini.  Al.
Alveus.  D.  Digitations of  the cornu ammonis.   Th.  Section  of optic thalamus.
M.  Section of cerebral medullary substance,  d., a. Descending and ascending fornix.
Trb  Corpus callosum (trabs cerebri).  M. Medullary substance.   J. Infundibulum.
Ca.  Anterior commissure.  Sp. Septum pellucidum.  p. Its peduncle.  II.  Optic
nerve.   H.  Hypophysis cerebri.

    The cerebral fissure surrounding the optic thalamus is broadest

behind the lowest portions of the descending  crus of  the  fornix

(Fig.  13,  in  front  of  a.),  to permit the passage  of the lateral

choroidal plexus, and is here termed the foramen Monroi.   The

ascending crus of the  fornix is also dissected  out  and  rendered 
20
Psychiatry.
visible in Fig. 13.   The inferior wall of the inter-brain is continued
into the inf undibulum (J), and communicates on the median surface
with the middle cerebral cavity.  The fornix from the fimbria to
the corpus candicans is the  genetic and permanent constriction-
margin of the fore-brain.   It was remarked at the outset that the
median surface of the fore-brain  surrounds the entrance into the
lateral ventricles in front of  the ganglionic proliferation, and that
the  ring  forms  a  hollow diverticulum at its anterior end, lying
below the rest of the hemispherical vesicle.  This diverticulum
develops  into the lobus olfactorius (Fig. 13, olf. and Fig. 4, below
the frontal end of the arched fore-brain and adjoining the island
of Reil). The olfactory lobe,  at the same time, forms the boundary
line of the median surface toward the external surface of the  fore-
brain, toward the Sylvian fossa and the island of Reil (Fig. 1 5, Ge.
and  Fig. 4).  The lobus olfactorius has, as Ave  shall  see, an ex-
ternal and an internal convolution  which  diverge  posteriorly in
the trigonum olfactorium (Fig.  18, olf.).
   The lumen of this genetic annular formation, which pertains to
the median surface of the prosencephalic cortex, may apparently be
traced on every section of  the brain to  the free margin of the
gyrus fornicatus.  The cortex  presents  its  free margin anteriorly
and posteriorly on straight horizontal (Fig. 5) as well as on sagittal
sections;  on frontal sections (Fig. 6) this margin is seen above and
below.
   The median  aspect (Fig.  13) shows the corpus callosum to  be
surrounded, in front, above,  and below,  by  the free margin of the
cortex (Gf. Trb.); below the corpus callosum, it presents the fimbria
of the fornix (Fi:).  Sections of the brain  prove that  the cortex
—the starting-point of all nerve fibres, encircles  the brain  like a
pleated cap.   Gratiolct described the cortex as a sac whose  rim,
the gyrus fornicatus, is drawn tightly together around the corpus
callosum.   This striking simile  is not entirely correct, for a smaller
sac, the olfactory lobe (Olf.)  protrudes anteriorly from the mouth
of the larger.
   But  in order to understand  clearly  the genesis of the  fixed
relation of these parts, it is well (when studying Fig. 13) to neglect
altogether the  corp.  callosum and the   anterior  commissure,
and  to imagine a  human  brain  minus  the  corp.  callosum.
Viewed  in  this way  the  gyrus  fornicatus will  be  found  con-
tinuous with the septum pcUucidum.   The primary margin of the
median cortical surface skirts the  fornix, as far  as  the vertex of 
Median Surface of tlie Brain.             21
the uncus, in the  disguise of the septum and the fascia dentata
 Tarini.
   The fornix,  however, taken  together  with the fimbria, does
not form a ring, but an arch.   The ascending crus of the fornix,
coming from the corpus mammillare, does not enter into account
at present.   Similarly the free margin of the median cortical sur-
face forms merely a ring-like arch about the fornix, which arch is
interrupted between the uncus and the orbital surface.    Beneath
the orbital surface lies the olfactory  lobe.   The external and
internal  margin  of the trigonum, the olfactory convolutions, iso-
late those convolutions  of the  cortical substance, which go to
form  the primary  median surface and the margin of the cortex.
The  external olfactory  convolution connects with the  uncus,
 skirting the island  of Reil and the orbital convolutions, while the
 internal  olf.  convolution is continued beyond the end of the in-
 ternal orbital convolution, on to the frontal terminus of the me-
 dian  cortical arch.   Lying  in the sulcus rectus,  and on the infe-
rior aspect of those convolutions which are continued from the
 convexity of the brain, the olfactory  lobe  and its trigonum are
bent  at right angles in spite of their anatomical connections.  To
 the basal position of the caudate nucleus this rectangular displace-
 ment  must be  attributed.   And yet, the trigonum and its crura
 form but the basal margin of the prosencephalic cortex.   Behind
the cortical  margin of the olfactory  convolutions a ganglion of
the  fore-brain,  the nucleus caudatus, presents its basal surface
 in the form  of the lamina perforata anterior (Fig. 18, olf. La.).
 The lamina perforata verges upon the basal prolongation of the in-
 ter-brain—the tractus opticus.  This marks the posterior boundary
 of the fore-brain.
    The  connection of the  gyrus fornicatus with the olfactory
convolution  is evident from a  peculiarity of structure common to
 both  : The microscopically minute nerve fibres  of  the  convolu-
 tions  of the  convexity are naked-eye appearances in these (olf.)
convolutions.  This  part of the cortex presents medullary spots,
both   in  the  substantia  reticularis of  the  uncinate convolution,
and in the white  streaks scattered  through the trigonum olfac-
torium.   The external medullary strand is  intimately  connected
with  the substantia  reticularis,  and so is the internal band, by
 means of  the ncrvus lancisii, which makes  a  detour  about the
anterior end  of the corp. callosum.
    The  passage of  the  corpus  callosum  from one hemisphere 
22                       Psychiatry.
to the  other causes that  part  of  the cortical substance which
immediately adjoins the fornix to separate from the gyrus forni-
catus as septum pcUucidum, the peduncle of which (p.) connects
with the lamina perforata anterior—i. e., with the basal mass of the
caudate  nucleus.  This peduncle  passes from cortical into gan-
glionic  substance.   It  represents  the projection-system  of the
septum's cortex.  Between the pedunculus septi (p.) and the for-
nix, the anterior commissure (ca.) breaks through in a transverse
direction.  The breaking through  of the corp. callos. shortens the
cleft for the falciform process of the dura mater by the height of the
septum, whose chambers correspond to the lower part of the lon-
gitudinal fissure between both hemispheres.   In animals  the
camera are abolished because  of the median adhesion  of  the
septa.
   The " peri-trabecular " substance of Huschke has a concentric
shape, and is made up of the gyrus fornicatus of Arnold and the
median surface of the marginal convolutions of the convexity.
These two concentric formations are separated from one  another
by the sulcus calloso-marginalis.  A fissure, which passes between
the corpus callosum and the marginal convolution of the  fore-
brain,  extends (genetically) as  far  as the  occipital  (ape) fis-
sure (Schmidt).  Behind  the  posterior central convolution  an
ascending branch leaves the sulcus calloso-marginalis, forming the
anterior border of the lobus quadratus—the praecuneus.   Its pro-
longation to the occipital  fissure  may  be either  very shallow,
or wanting altogether as in the brains of primates  (Fig.  14, cm.).
The  lobus  quadratus is the  mesial  representative  of the  region
of the superior parietal lobule.  The demarcation of the gyrus for-
nicatus  is continued for some little distance in the temporal lobe
by the  extension of the sulcus calcarinus anteriorly.  For the
sake of completeness I propose at the close of this description
to refer to a special complication  of the gyrus fornicatus—to the
uncinate convolution.
   Caudad of the lobus quadratus we find the lobus triqueter
(the cuneus), the median surface of the superior occipital  convo-
lution.  The lobe is bounded  by  two >-shaped,  deep fissures,
which converge toward the gyrus fornicatus, of which the superior
is called sulcus occipitalis internus  ; the inferior, sulcus calcarinus
or sulcus hippocampi.  The latter is  one  of the  most constant
fissures of the primate " type "; it can be discovered in the smooth-
est primate brains which have not yet developed either the exter- 
Median Surface of the Brain.             23
nal occipital fissure or the sulcus centralis.  It receives its name
from  the  calcar  avis (pes  hippocampi  minor);   for, in  conse-
quence of the thinness of the mesial wall of the  posterior horn,
the calcar avis is formed by the convex protrusion of  the  reverse
(Kehrseite) of this fissure upon the inner  wall of the posterior
cornu,  just as the next following eminentia collateralis Meckelii
is the converse of the  next external fissure (S.O.T.F.).  The sulcus
calcarinus  is  in reality (--shaped  (Fig. 14,  £c).  In  the  human
brain the  longitudinal  fissure  of  the h-  is frequently  bent at an
angle open posteriorly.
    In addition to  the occipital fissure of  the  sulcus  calcarinus,
the  median surface presents
two  other fissures—Ecker's
occipitotemporal   fissures.
But these  fissures do  not be-
long to that  vertical  portion
of the median surface consid-
ered hitherto, which lies next
to  the falx cerebri;  for we
must remember that  the me-
dian surface lies in two planes
meeting at an  obtuse angle.
The longer vertical division,
extending  from the  frontal
end to the extremity of the oc-
ciput, rests upon the falx cer-
ebri ; the  oblique  horizontal
division,   extending  merely
from the  vertex  of the occi-
put to the temporal end, rests
upon the tentorium cerebelli.
The  superior occipito-temporal fissures, together with the sulcus
calcarinus, bound a  convolution  which,  tapering  anteriorly and
uniting with the uncinate convolution, bears a strong resemblance
to  the tongue of  a dog;  whence  the name,  gyrus glossiformis.
The superior and inferior occipito-temporal fissures enclose a con-
volution broadest  at  its middle part, the gyrus fusiformis.   The
latter is succeeded by the marginal convolution  of the temporal
lobe, which belongs to the convex surface as well  (L.3).
    At  the anterior margin of the temporal lobe the three convo-
lutions of  the  convex  surface  unite  to form a transverse-arched
              Fig. 14.
   Median Surface of the Primate Brain.
  Fr.,   Tm.   Front., temp.  end.   L.occ
Occipital lobe.  an. Calloso-marginal con-
volution.  S.occ.  Internal occipital fissure.
St. Sulcus calcarinus. L.s Third frontal con-
volution. Gf.  Gyrus fornicatus.  Qu. Lobus
quadratus. Cun. Cuneus. Gl. Gyrus glossi-
formis.  Fus.  Gyr.  fusiform.  L.3, L.2, L.J
Temporal convolutions.  A. Amygdala,  unc
Uncus.  Trb.  Corp. callosum (trabs).   Sp.
Septum  pellucidum.  Th.  Optic thalamus.
Ca. Anterior commissure. 
24
Psychiatry.
anastomosis,  the  cortical portion  of  which  connects with  the
uncus (Fig. 14, Tra.).
   A few words must here be added  in reference to  the cornu
ammonis, a formation complicating the temporal end  of the gyrus
fornicatus.  The cortical substance of the gyrus fornicatus, which
terminates with a free margin over the  corpus callosum, presents
on cross-section, as does every convolution, an [\ surrounding the
medullary substance.   Burdach applied the  term  cingulum  to
that portion of the gyrus fornicatus extending as far as beneath
the splenium corp. callosi. At the temporal end of the gyrus forni-
catus, in the gyrus uncinatus, the cortical substance does not ter-
minate with a free margin until the middle portion of the convo-
lution has undergone an c/vshaped involution (lamina convolutd),
and the anterior portion has been divided up wave-like ; the wave-
tops facing the inferior cornu are the so-called digitations.  The
C/>shaped involution allows the margin  to  become quite free, to
rise above the medullary substance, and to appear from out of the
involution-folds as the fascia dentata, the notched surface of which
is due to constricting vessels.
   The cornu ammonis possesses four adjacent longitudinal emi-
nences:  1. The gyrus uncinatus, the core  of the cornu ammonis
subiculum.  2. The Fascia Dentata Tarini (Fig. 13).   The Fasciola
Cinerea (Arnold) is a continuation of  the  fascia dentata  on  the
lower surface of the great commissure, commissural fibres having
perforated part  of the median  cortical  substance some distance
behind the septum.   The cornu ammonis, unusually large in car-
nivora, rodents, etc., lies adjacent to a considerable portion of the
inferior surface of the corpus callosum, and extends far to the front.
3. The Fimbria (Sus.), the projection bundle of the cornu ammonis.
Additions from other parts of the gyrus fornicatus transform this
into the descending crus of the fornix (Fd.).  4. The Alveus (Fi.),
whose white substance, spread over its  own gray cortex, over the
stratum convolutum, is continued into the cord-shaped fimbria. The
alveus represents  the ventricular surface of the cornu ammonis,
which surface protrudes as though it were embossed from the inner
wall of the inferior horn.   The name, alveus, is quite appropriate,
for  the  stratum convolutum  is surrounded  trough-like by  this
medullary layer, which is curved, with its convex surface  toward
the ventricle. The  surface of the subiculum, together with the
fascia dentata, forms a continuous cortical layer, which is folded
CO-shaped from right to left.  The surface  of the cortex is hid in 
Basal Surface of the Brain.              25
the depths of this scroll.  The alveus corresponds to the white
substance of the convolutions,  and consequently faces the  ven-
tricles.  The uncus also is a complex formation.  Its apex or pos-
terior portion alone contains the forward part of the free median
cortical margin, which projects in a transverse direction above the
subiculum cornu ammonis, and yet is a part of it.  The appear-
ance of a  longitudinal anterior flexion of the uncus, distinct from
the cornu  ammonis, corresponds to the convexity of the amygdala;
this irregular gray  mass  lies  in  front of the cornu  ammonis, and
covers over the  fissure which otherwise would  have been evident
on the brain  surface at its point of flexion.

B.—GANGLIA  OF THE PROSENCEPHALON, THALAM-
    (DI-) ENCEPHALON,  MESENCEPHALON, AND MET-
    ENCEPHALON.

    The cerebral cortex and its white substance  betray, as it were,
their morphological independence by the constriction round about
the ganglia (Fig. 4, g. Fig. 15),  and by the ease with which both
the island of Reil and its medullary  substance can be dissected
out from  the external surface of the large ganglia.  This anatom-
ical independence  is in  accord with  the physiological indepen-
dence of the fore-brain from  the rest of the  brain-substance.
    In order to demonstrate the entire natural  surfaces of  the
cerebral ganglia  and the brain-axis, it is necessary to  remove, by
a curved  incision (passing around the island,  on the floor of  the
Sylvian fossa), the hemispheric arch, which corresponds to  the
cerebral mantle  of  Burdach,  in contradistinction to the nucleus of
the brain  (which includes the island, ganglia, and brain-axis).
    The basilar aspect of the nucleus,  or rather of  the brain-axis
(Fig.  15),  presents a free  surface in front of the tractus opticus, in
the form of the lamina anterior perforata ; the last-named structure
is separated  on each side from the island by the external olfactory
convolution, before it joins the gyrus uncinatus.   The convolu-
tions  of  the island converge  toward this external  medullary
strip  of the  trigonum olfactorium, and form  generally a single
convolution,—the  peduncle  of the island,—while  they  diverge
above toward the operculum, dividing into  five or seven convolu-
tions.   To the inside of  the island, and the  outside of the caudate
nucleus, extends the plane of the incision which  separated  the
trunk from the  cerebral  mantle, as though  the former were  the 
26
Psychiatry.
nucleus of the latter.  Just-as the hemisphere describes an arc with
a frontal, a temporal, and an occipital end, so we  shall find  that
the collected fibres of the corona  radiata describe a similar curve
at their entrance into the cerebral trunk.  A section like that repre-
                                 Fig. 15.
             Basilar Surface of the Brain-Axis and the Cerebellum.
   Fr., Tm., Occ. Section through the medullary substance, radiating from the frontal,
temporal, and occipital portions of the cerebral mantle into the brain-nucleus.  Js.
Island of R.  Ge. Med. substance upon the external olfactory convolution, pa. Lam-
ina perforata anterior.  II. Optic nerve ;  the optic tract is divided posteriorly into an
internal and external division.  J. Infundibulum.   M. Corp. mammillare.  L. Lamina
perforata posterior. Pd. Pedunculus (crus) cerebri.  T. Tractus transversus pedunculi.
V. Pons  Varolii.   P. Pyramis.  O. Olive.  R. Restiform body.   M. Medulla spinalis.
III.  Oculomotor nerve.   IV. N. trochlearis.  V.  Trigeminal nerve.  VI. N.  abdu-
cens.  VII. Facial nerve.  VIII.  Auditory nerve.   IX. N. glossopharyngeus.  X. N.
vagus.   XL N. recurrens Willissii (accessory  nerve).  XII. Hypoglossal nerve.  Qu.
Inferior  surface of the lobus quadratus, superior lobe, of the cerebellar hemisphere.
p.p.  Lobus posterior inferior (semilunaris inferior), i.i.i.  Lobus  inferior (lobusgracilis
et biventer).  A. Amygdala.   Fl. Floculus.  Vr. Inferior vermiform process.

sented  in Fig. 15 will present,  therefore,  a frontal and  temporal

end (F., Tm.), and  between  the two a  parietal and  occipital  sur-

face (Figs.  16, 17, P. Occ).  The marked convexity of the trunk, 
Basal Surface of the Brain.              2 7
causing it to protrude to the outside from under the  insular con-
volutions at this section of the corona radiata, is due  to the large
size  of the nucleus lenticularis,  and  furthermore, the temporal
portion of this nucleus projects below the cerebral trunk, a fact not
easily appreciated on the hardened specimen, owing to the  slight
contrast of colors.  The  caudate nucleus passes from the fore-
brain to the basal surface,  and there  appears as the  lamina per-
forata anterior.   The inter- and  mid-brain are  continued to the
base of the cerebrum through the tractus opticus, which, together
with the optic chasm, constitutes the  posterior boundary of the
fore-brain.
    The infundibulum represents  a basal continuation of the cere-
bral gray  substance surrounding the  cavity  of  the  thalamen-
cephalon, and the corpus candicans must be regarded  as medul-
lary substance  of the thalamencephalon,  extending from the
anterior tubercle of  the  thalamus to the basilar surface of the
brain (Fig. 13, m. a.).
    The pedunculus (Pd.) cerebri, which is bound  from the fere-
brain  to the spinal  cord, covers  superficially and  laterally the
anterior circumference of the mesencephalon. The median lamina
perforata  posterior forms the median suture (raphe) of  the two
halves of the tegmentum, which  connects the mes- and thalamen-
cephalon with the spinal cord.  The  pedunculus cerebri is crossed
in the median line by the third pair of nerves (III. oculomotorius).
The left half of the pedunculus cerebri is crossed  by  a tract (the
tractus transversus pedunculi—Gudden) which  does not always lie
as superficially as here indicated, and connects the anterior end of
the peduncle  with  the  superior  corp.  bigemina.  The  pons
Varolii  constitutes the  basilar  surface (Kehrseite) of the epen-
cephalon.   From the pons there emerge  laterally the trigeminal
nerves, and  inferiorly the abducens, facial,  and acoustic nerves.
Below the pons Varolii  and between the pyramids we come
upon  the  anterior furrow of the cerebral axis,  which  is well
developed even between  the crura.  The  floor  of  the  anterior
cleft is analogous to  the lamina perforata posterior lying between
the paired peduncles, for its floor reveals the median surface of the
raphe of  the posterior  division of the oblongata.  And  in the
oblongata also the raphe divides the prolongations of the tegmen-
tum.  The oblongata can be divided into a superior  and an infe-
rior portion.  The superior division extends to the inferior mar-
gin of  the olivary bodies, the inferior half to the last decussating 
28
Psychiatry.
bundle  of  the  pyramids.   A  longitudinal  fissure  divides  each
olivary body toward the median line from the pyramids, and toward
the  outer side  from  the  region of  the  funiculus lateralis.    On
closer examination  the olivary bodies do  not  appear smooth, but
striated, owing to  the passage  over them of  oblique, slightly de-
scending bundles (stratum zonale)  which originate in the  corpus
restiforme.   As a rule the  stratum zonale covers  all the longitu-
dinal fibres coursing back of the pyramids.   If there be  a super-
ficial  longitudinal  bundle  of  fibres  to the  inner  side  of   the
olivary body,! this is termed fasciculus internus;  if to the outside,
fasciculus  externus.   These fasciculi may be nothing more  than
pyramid-fibres which the stratum zonale has  separated  from  the
main body  of the pyramids.   Behind  the funiculus lateralis of the
oblongata lies its most posterior longitudinal  elevation, the corpus
restiforme of the cerebellum  (Fig.  15, R.).
    The basal surface of the human  isthmus presents many striking points of con-
trast with the brains of lower mammals, and even with the brains of primates.   Entire
structures seem to appear,  or to disappear in man.  On  the whole, the pedunculus
cerebri in animals is thin and possessed of so few nerve-tracts that the convexity of the
tegmentum lying behind it causes it to bulge out.  The pons appears low ;  next to the
pyramids  rectangular formations are visible, which are made up of transverse fibres
(corpus trapezoides).  The olivary body, common to man, is wanting.  I  have  shown
that all these differences of structure depend  upon a single  factor, upon the greater or
lesser development of the fore-brain.  The smallness of the prosencephalon in mammals
causes a diminution  in the  thickness of the  peduncles, in  the height of the pons, and
in the size of the pyramids.  Similarly the appearance of the trapezoid body and the
disappearance  of the olivary structures are due to the smallness of the fore-brain.  If a
mammal, whose basilar brain surface is as unlike that of man as is the brain of mustela
(Fig. 10,p. 9), could develop mightier hemispheres, then its pes pedunculi would increase
in size and in the number of its nerve-bundles, for the simple reason that the pes pedunculi
to a great extent is the continuation of the medullary substance of the hemisphere.
Furthermore, inasmuch as  the pyramid,  the prolongation  of the pesped. gets  but a
part of  the latter's fibres, while a large part of peduncular fibres reach the cerebellum
by way of the  brachium-pontis, we shall find that the number of bundles in the pons
is dependent  in the first instance upon the number in  the pes pedunculi, and in
the second instance upon the greater development of the medullary substance  of the
hemispheres, and upon the cerebral cortex whence the white fibres emanate.   The
more highly developed these cerebral masses, the greater the extent of surface from
which the pons-fibres can  originate.  In man the  pons is so  excessively developed
longitudinally that the deeper transverse bundles are completely covered. In mammals
the pons is so short that the course of  the pyramid is  usually prolonged anteriorly and
remains uncovered.   For this rea.son transverse bundles (corp. trapez.) come into view
next to the pyramids ; in man these bundles are screened from view by the lower bun-
dles of the  pons.  The  corpus trapezoides is, therefore,  not wanting in  the human
brain ;  it  is simply  invisible on the basilar  surface.  Nor is the olivary body really
missing in animals.  It lies behind the pyramids ; from  this position it  has been dis-
lodged by the thickness of the pyramids in man, pushed to the side, and made visible 
Basal Surface of the Brain.               29
on the basilar surface.  We infer from such facts as these, and from a study of the
ganglia, that the cerebral structure is governed by a law which establishes a harmonic
dependence between the formation of the brain-axis and the development of  the
functionally highest organ— the fore-brain.   (Details to be  found in the " Mittheilun-
gen der anthropologischen Gesellschaft," Vienna, 1870.)
   The peculiarities of the human brain might not inappropriately be said to be
"mentalized " (durchgeistigt).  The lower forms of primates  possess brains whose
trunk shows evident transitional stages between the lower and  higher forms ; for in-
stance, the visible co-existence of olivary and trapezoid bodies (Fig. 11, p. n, Rh. O.).
In the highest carnivora (bear) the brain presents the higher transitory stages of brain-
structure.  So early an observer  as Stannius knew of the olivary bodies of water-
mammals.  The metencephalon, the oblongata, is apparently longer in animals owing
to the shortness of the pons, and, with the exception of  the pyramids, more highly
developed than in man.
    At  the level of the  entrance of the brachium pontis,1 in front
of the  seventh and eighth  pairs of nerves, the cerebellum presents
the  sulcus magnus horizontalis.  From the  basilar surface  the
lobus quadratus (Qu, Fig. 15) can be seen projecting  above  this
furrow.  This furrow divides deeply the convolutions of the pos-
terior (subtentorial) surface of the cerebellum from  those of the
basilar  surface.   For our purpose  it will be sufficient to give
 Henle's  simplified account  of  the  basilar  lobes.   From before
backward we have the following hemispheric lobes:   1. The floc-
 culus.   2.  The amygdala.   3. The inferior lobes (i. i. i.).  4- The
 posterior inferior lobe (pp.).  The median lobules:  1. The nod-
 ulus.   2. The uvula.   3. The pyramid.  4.  The posterior vermis.
 These are not basilar  formations, but  are covered by the  oblon-
 gata.
    The pros- and thalam-encephalon  possess surfaces which look
 from below into the cerebral ventricles, and consequently can be
 viewed from above (Fig. 16).
    A  bundle of  fibres belonging to the corpus striatum  corre-
 sponds to the stria cornea (stria terminalis), which appears to be
 the line of  demarcation between  the fore- and  inter-brain.   The
 fibres  of this bundle from the temporal lobe  pass into the nucleus
 caudatus along the entire length of the latter.  The surface of the
 stria cornea is formed by  a fold of  the ependyma, underneath
 which a large vein collects the  lateral branches from the surface
 of the nucleus caudatus,  and conducts them  to the vena  magna
 Galeni, which is lodged in the membranous covering of the corp.
 quadrig.  The cavity of  the thalamencephalon (ventriculus  III.)
 forms a circle around  the  commissura media.    If  the mem-
1 Processus cerebelli ad pontem. 
30                          Psychiatry.

branous roof  of the 3d ventricle were left intact, and the aquae-
ductus Sylvii properly closed, a cast of the third  ventricle could
be taken.   This cast of  the third ventricle would  resemble a ring
whose  opening  would  correspond to  the median  commissure.
Interiorly the  ring would present a  projection—the cast of the
                                Fig.  16.
       Superior and Posterior Aspect of Brain-Axis, and of the Cerebellum.
    J. Island.  F., P., Occ. Frontal, parietal, and occipital portions of the projection-
system (radiating fibres from the  cerebral mantle).  Nc.  Caudate nucleus.  Str. Stria
cornea.  L. Linea aspera.  Ca.  Anterior commissure.  Fx. Descending crus of the
fornix.  V. III. Ventricle.  Cm. Median commissure.   Th. Optic thalamus.  Tb. a.
Its anterior tubercle.  Tb. m. Its median tubercle (elevation).  Pulv.  Pulvinar.  con.
Conarium, from the sides of which the plastic longitudinal prominences of the habenu-
lae originate.  Bs.  Superior  bigeminal  body.  Bi.  Inferior bigeminal  body.  brs.
Superior arm.  bri.  Inferior arm of the corpus quadrigeminum.  CI. Central lobule
of the  superior vermiform process.  M. Its  mons.  Fc Folium cacuminis (the top
layer of the superior vermiform process).  Al. Aire of the central lobule.  Qu. Lobus
quadratus (Burdach),  superior  lobe (Henle). Sl.s. Superior  posterior lobe (lobus
semilunaris superior).  Sl.i. Lobus semilunaris inferior—(posterior lobe—Henle).

infundibulum.   Behind the  caudate  nucleus and the  stria,  the

anterior  commissure  and the  descending  crus of the  fornix, we

come upon the  thalamus  opticus.  Its  surface  is  on  the whole

wedge-shaped, with a  blunt anterior  edge, and  a  convex, broad-

faceted ending at the pulvinar.   Its median surface is composed of 
                Dorsal Surface of the Brain.            31

gray substance (central cavity gray), for the united cavities of the
primary medullary tube, from the primary anterior cerebral vesicle
to the end of the spinal cord, are lined with gray substance.  This
narrow gray, cleft-shaped covering of the diencephalon passes in
the mid-brain into the aquaeductus Sylvii.
   The surface of  the optic  thalamus presents several promi-
nences.  The best defined is the  habcnula—the pineal peduncle
(between  brs.  and  F. Fig. 17).   The surface of the habenula,
which is connected on  both sides with the pineal region, receives
white substance, as does the entire surface of the optic thalamus,
from  the stratum zonale.  The stratum zonale of the habenula has
the appearance of being torn off anteriorly after the removal of
the adherent membranous covering of the  ventricle  from  the
ependyma.   From this the  false inference was made that  there
was  a connection between the  fornix and  the  habenula.   The
other three  prominences  are:   2. The anterior  nucleus (Genu
anterius Gratiolet) which tapers  tail-like backwards and outwards
tuberculum anterius  (Burdach), (Fig. 16, Tb. a.).  3. The  median
protuberance (tuberculum medium) which arises simply from the
demarcation  of the tuberculum anterius and the flattening of  the
thalamus  behind the habenula.   4.  The  pulvinar, which in  the
human subject presents the shape of a posterior free eminence.
   In man the ganglia  of the mesencephalon, the corpora quadri-
gemina, encroach considerably upon the thalamencephalon.   The
corpora quadrigemina comprise the superior and inferior corpora
bigemina.  If the pineal body (Fig. 17, con. cp.) be lifted from  the
back, we come upon a  flat triangular space with its base above,
situated in the middle of the superior corp. bigem., which receives
the posterior surface of the pineal bod}-, and bends over into  the
posterior commissure.   We notice also a groove, open posteriorly,
between the upper surface of the corp. quadrigemina and the lower
surface of the  conarium  which  latter rests  upon the  former.
This is the reverse of the convexity of the posterior commissure
(convex anteriorly).  This commissure, with its convexity looking
anteriorly, is, therefore, a transverse curved medullary lamina, and
not a funicular formation, as it would  seem to be from an inspec-
tion  of the anterior surface.   The superior corpus bigeminum is
connected with an apparently columnar medullary border, which,
concave posteriorly throughout its entire length, courses between
the pulvinar and the corp. genie, internum.  This is the brachium
corporis bigemini superius (Fig. 17, brs.).   The superior terminus 
32                          Psychiatry.
of the corpus geniculatum internum also tapers toward  the  corp.
bigeminum superius, combining with the latter under the brachium
corp. big. sup. mentioned above.  The  arm of  the  superior  corp.
quadrigem. forms the  boundary between the mes- and  thalam-
encephalon.  The superior half of the corp. bigeminum inferius is
connected with a flat, white  medullary structure appearing from
under  the  internal genu  (brachium  corporis  bigemini  inferius,
Superior and Posterior Surfaces of the Prosencephalon of the Lobus Candicis (Stamm-
            lappen), of the Thalam-, Mes-, and Met-encephalon.

    J. Island.  P., Occ. Parietal and occipital divisions of the projection systems from
the cortex.  Nc. Caudatus nucleus.  St. Stria cornea.  Th. Opticus thalamus. Pulv.
Pulvinar.  Ge. External geniculate body.  Tr. Optic tract,  Gi. Internal geniculate
body.  V.  Third ventricle. Hb. Habenula conarii. con.  Conarium.  cp.  Posterior
surface of the posterior commissure.  Fr.  Frenulum,  ve. Superior medullary velum.
Bs., Bi. Corpus bigeminum superius et inferius.  brs., bri. Brachium superius et  in-
ferius  corporis quadrigemini.   Ls., Li. Lemniscus superior et  inferior (upper and
lower  fillet).  5.  Locus cceruleus.  £- Auditory nucleus.  7. 6. Common nucleus of
the  6th and 7th nerves.   8. Ascending root of the  8th nerve  (Engel) ; auditory rod
(Bergmann).  Br. Brachium pontis.   R.  Restiform body.  Pr. Processus  cerebelli
ad cerebrum.   VIII. Striae medullares nervi acustici transversae (auditory striae).   12.
Region of  the hypoglossal nucleus.  10. Ala cinerea, Arnold (nucleus of the vagus.—
Stilling),  ob. Obex : cun. Fasciculus, cuneatus Gr. Fasciculus  gracilis.  RL. Tuber-
culum cinercum, Rolando.  L. Lateral column.
    Note.—This drawing reproduces the exact position of the  cerebral trunk within
the cranial  cavity, taking into account the parietal flexure.

Fig.  17 bri.).  This brachium passes into the white surface  of the

inferior corp.  bigem.  The  superior corp. bigem.  presents a gray

surface, more especially, however, in animals.  Below the brachium

corp. bigem. superius lie  the spindle-shaped  corpus  geniculatum

internum (Fig.  17,  gi.), and the club-shaped  corp.  geniculatum

externum,   growing  smaller  as  it  nears  the   tractus  opticus 
Dorsal Surface of the Brain.              3 3
(Figs. 15 and  17, ge.).  The  transition of the external corpus
geniculatum into the optic tract is the  only part that is visible.
A distinct  demarcating  furrow  lies at the  boundary  between
the corp. genie, int.  (gi.) and the  inner  ribbon-shaped stria of the
tractus (Fig. 15).  This band appears (at least below the surface) to
pass  into the  thalamus in front  of  the corp. geniculatum inter-
num.  If the size of  any brain-formation increases with an increase
in the  size of correlated  parts, we may maintain  that  the  cor-
pora geniculata will increase  with a large growth  of the corp.
quadrigemina ; and,  on  the  other  hand, that  in these very
animals disappearance of the pulvinar causes a diminution in the
size  of the optic  thalamus.   I was the  first to observe, on longi-
tudinal  sections through  the  brain  of  a new-born  cat, that  the
largely  developed  corp.  genie,  externum ascends beyond the
optic thalamus.   Forel has given a more detailed description of
this.  Accordingly,  the development of the  corpora  geniculata
is dependent upon the mesencephalon.
    Between the posterior corp. bigemina a paired-conical column
is formed, which, broadening below, passes as frenulum into the
velum medullare superius (Fig. 17, ve.), and is continued through
this  into the medullary substance of the vermis superior.   The
velum  m.  superius is covered  by the  lingula,  the foremost
convolutions of the  vermis  superior.   Stilling discovered  the
delicate bands of the lingula which lie immediately upon  the
processus cerebelli  ad  cerebrum  (Fig. 17, to  the right of Ling).
The  posterior surface of the after-brain would come into view
below the mid-brain as a freed portion  of  the brain-axis, were it
not  covered by the  cerebellum (hind-brain), (Fig. 16), which must
be severed  at its connecting arms,  if  a view of said posterior
surface is to be obtained.
    On  the  posterior subtentorial surface of  the cerebellum  the
mons (Fig. 16,  M.), the third and largest division of  the  superior
vermiform process,  covers the central lobe, and this in  turn the
lingula  of the medullary velum.   In  a similar  fashion the lateral
divisions of  the lingula (frenula lingulae) are  covered by the  lat-
eral portions of the central lobe—by the alae, and these  in turn are
concealed on each side beneath the hemispheres of the mons, the
lobis quadratus (lobulus superior of  Henle), which projects ante-
riorly beyond  the alae (Fig. 15, 16, Qu.).  The great  horizontal
fissure divides the posterior lobes  of the upper and lower surfaces
of the cerebellum, the inferior post, lobe projecting in an occipital 
34
Psychiatry.
 direction beyond the former (Fig.  16).  In spite of the manifold
 numerical relations and the still more manifold modes of connec-
 tion between the median and lateral cerebellar covolutions (which
 Malacarne counted and Stilling studied most thoroughly), an in-
 crease of lateral convolutions seems to correspond  to  an increase
 of median convolutions; and yet there is one exception to this
 superficial  agreement.  At the bottom of the  great horizontal
 fissure all the convolutions of the upper semilunar lobe (superior
 posterior lobe)  are united into a single layer of vermiform  con-
 volutions, in the folium cacuminis (Fig. 16, Sl.s.  Fc).
   After dissecting away the cerebellum, we can  examine the pos-
 terior surface of the brain-axis. The middle of the region between
 corp. quadrigemina and the entrance of the processus cerebelli into
 the cerebellum  is taken up by the velum medullare (Fig. 17, to the
 right), developed from the frenulum.   The velum  medullare and
 the frenulum constitute the genuine processus cerebelli ad corpus
 quadrigeminum.  At the superior margin of  the valvula cerebri,
 the IV. nerve is seen to emerge (Fig. 17, IV.).  The  lateral  mar-
 gins of the velum verge upon two powerful flat bands, the Binde-
 arme; these were  falsely  termed processus  ccrebelli ad corpus
quadrigeminum, and correctly described by Stilling as the processus
cerebelli ad cerebrum) The processus ad cerebrum begin not quite
 at the corp. quadrig. and terminate at the frenulum lingulae (Fig.
 17, right), in the direction of the cerebellum.   Superficial bundles
 of fibres emerging from the velum medullare  and twining around
 these processus ad cerebrum, separate  them from the  corp. quad-
 rig. ; these bundles pass outward and' over the processus cerebelli
 and  disappear  in  the pons.  Leveille" was the  first  to  make  a
 drawing  of these bundles.   I have designated these  bundles as
 lemniscus  inferior (Fig. 17,  Li.), or  the cerebellar   bundles of
 the fillet.  The superior fillet, the lemniscus  Reilii (laqueus,  Fig.
 17, Ls.), covers the  proces.  ad cerebrum like  a  three-cornered
 cloth, lying external  to  the inferior fillet.  The superior fillet ex-
 tends from the  corp. quadrigemina to the superior margin of the
 pons.
   Toward the base  of the brain, on the posterior surface of the
 trunk, the  posterior aspects of the  pes pedunculi   and of the
 pons  are visible.  But  the  fillets, the processus  ccrebelli ad cere-
 brum, and  the  velum  medullare  inferius,  constitute  a series of
 structures which reach the  surface  behind  the pes pedunculi
1 Superior peduncles of the cerebellum.—S. 
The Brain-Axis.
35
as integral parts of the tegmentum.   In the cerebellum the con-
tinuation  of the velum medullare and of the processus ad cerebrum
passes with a free medullary surface behind the  rhomboid  fossa
and there forms its roof—the tectum fossce rtiomboidalis.
   The central gray substance (Hohlengrau) of the mid-brain, sur-
rounding  the aquceductus Sylvii, dilates beneath the velum medul-
lare into a semicircular canal with furrowed floor.  The divergence
(cordward) of the processus cerebelli ad cerebrum allows the central
gray substance to expand most in breadth between the points of
emergence of the two auditory nerves.  At this level the corpora
restiformia, which appear to be in  direct connection  with the
funiculi  graciles approach the  central  gray  to  form its lateral
boundaries.  These structures, converging symmetrically at the
lower end of the central gray substance, cause the  latter to deepen
at the same time that it tapers  to  a point.   Inferiorly the fossa
is continued in funnel-shaped fashion into the central canal of the
after-brain.   This portion of the central gray substance has been
termed fossa  rhomboidea, from its  being enclosed  between the
angles formed by the meeting of the processus ad cerebrum above,
and  the  pedunculi cerebelli beloAV.  The fossa rhomboidea has
important relations to the origin of cerebral nerves.
    The same median furrow which was noticed on the ventral
wall of the  aquaeductus Sylvii divides the fossa rhomboidea into
symmetrical halves.  The cmincntice teretes, descending from the
aquaed. Sylvii  on each  side of  the  median furrow, enlarge into
an oval area just above the exit  of the eighth nerve (Fig.  17, 6,7).
To this area, which is intersected by the central fibres of the sixth
and seventh pairs of nerves, various names have been given, viz.:
abducens-facialis  nucleus—Stilling  and  Clarke  ;  abducens  nu-
cleus—Deiter;  facial nucleus—Schroder.
    To the outer side of the superior half of this prominence we find
a long bluish groove, the fossa cosrulca.  The  bluish color is due,
according to the laws of refraction through cloudy media, to the
black cells  lying immediately below the transparent ependyma.
I have shown  that  in  this groove  one of the roots of the fifth
nerve takes its origin (Fig. 17, 5).
    Below  (caudad)  the  fossa   cosrulca, the  eminentia  teres is
bounded laterally by a rhomboid  elevation  (region of the viii.
nucleus), extending  at  its broadest  part quite  to  the  median
line.   Striae medullares transversae—the  superficial posterior roots
of the viii. nerve—may divide this rhomboid  into a superior 
36
Psychiatry.
and an inferior triangle (Fig. 17, viii., 8, 8).   The  acoustic nuclei
and the joint nucleus of the sixth and seventh nerves are frequently
separated from  one another by several obliquely ascending striae
medullares  (Engel,  Bergmann,  " Klangstab ") ;  occasionally  the
eighth  nucleus is covered by these strice (Fig. 17, 8).  The inner
margin of this elevation bears on the lower part of the rhomboid
fossa to the outer  side.  But this does not increase the breadth
of the eminentia teres,  for its outer margin converges below tow-
ard the median furrow, to  bound  a median triangular  elevation,
which represents the region of the hypoglossal nerve (Fig. 17,  12).
There are two reasons for this narrowing (below) of the eminentia
teres : First, the converging fasciculi graciles crowd in upon  the
fossa rhomboidea at its point of junction with the canalis centralis ;
and, secondly, the triangular nucleus of thetenth nerve, enlarging
from above downward, edges its way in between the origin of the
eighth nerve  and the eminentia teres (12).  This is the posterior
nucleus of the vagus, which a grayish color (ala cinerea—Arnold)
distinguishes from the whiter triangular area of the twelfth nerve,
which area  is covered by transverse fibres of the vagus.
    A sling-shaped  commissure, pointed below,  often  causes a
columnar elevation of the  ala cinerea.  At the lower angle of
the rhomboid fossa, the obex (Fig. 17, Ob.) effects a connection
with the membranous roof  of the metencephalon and the choroid
plexus, similar to the passage of the fimbria into the membranous
roof of the  diencephalon.
    This obex, a vestige of the fcetal posterior roof of the rhomboid
fossa, remains attached to the latter when  it is separated (by  dis-
section) from its surrounding parts.
    Let us pass now to the consideration of the nerve-tracts to be
found on the posterior aspect of the after-brain.  The corpus res-
tiforme1 emerges from  the cerebellum at about the level at which
the  posterior surface of the processus cerebelli ad cerebrum  dis-
appears within that organ (Fig.  17, R).  Above the decussation of
the  pyramids, which begins a short distance below the formation
of the central canal, the corpus restiforme appears to divide into
the funiculus cuneatus and f. gracilis (Fig. I7,cun., Gr.).  And yet
the latter are separated from the corpus restiforme  by a shallow
transverse  furrow,  which  proves  that  they cannot arise  from
a division of the corp. restiforme of the same side.  The origin of
the  funiculi graciles et  cuneati is marked by gray substance within
these plastic, conical protuberances.
1 Pedunculus cerebelli ad medullam oblongatam. 
Architecture of the Brain.
37
   Both these tracts of the oblongata are continued into the pos-
terior columns of the spinal cord.   In the cervical spinal cord the
triangular column of Goll must  be regarded as the prolongation
of the funiculus gracilis.
   These posterior columns of the oblongata do not abut, as is the
case in  the spinal cord, upon the lateral columns (Fig. 17,  L.).
The superior beginnings of a caput cornu posterioris, of  the gela-
tinous substance of the gray spinal-cord nucleus, forces its way
to the  surface between the lateral  and posterior fasciculi of the
after-brain.  This spindle-shaped mass—the tuberculum  cinereum
Rolando (Fig. 17, RL.)—is the nucleus of origin of the ascending
root of the fifth nerve, which is equivalent to a posterior root of
the spinal cord.  The posterior roots of the spinal cord also pos-
sess ascending fibres.  The root of the fifth nerve covers the sub-
stantia  gelatinosa with a  thin film  of  fibres, which  do  not alto-
gether hide the gray nucleus (tuberculum cinereum) below.
    On  the anterior basilar surface of  the trunk  the  inferior
margin  of the olivary body marks the  boundary  between  the
upper and lower  halves  of the oblongata, which are  more unlike
each other in structure than are the  superior half of the oblongata
and the inferior half of the pons.   On the posterior surface of
the isthmus, the  boundary of the lower half of the  after-brain is
marked best by the superior margin of the tuberculum  cinereum
Rolando.  The  plastic  prominences of the  lower  half of the
oblongata are in  due succession from the anterior  to the posterior
median furrow of the trunk, as follows : 1.  The pyramids bounded
by the  roots of the hypoglossal nerve (Fig. 15, P.); 2.  Funiculus
anterior;  3. Funiculus  lateralis  (lateral  column),—these  are
separated by the anterior roots of the  uppermost cervical nerves
(Fig. 15,  1, 2,); 4. Tuberculum cinereum Rolando (Fig. 17,  RL.);
5. Fasciculus cuneatus (Fig, 17, cun.);  6. Funiculus gracilis (Gr.).
    The final transition of the medulla oblongata into the spinal
cord is effected  at  the level of the origin  of the third cervical
nerve.
REMARKS ON THE ARCHITECTURE OF  THE  BRAIN.

    The structure of the  cerebral cortex, like  that  of a crystal,
can  be studied best from its cleavage-surface.  The cortical sub-
stance contains two distinct sets of fibres.   First, we  observe that
the cleavage-surface of each convolution  presents radiating fibres
which are quite  distinct  from radiating blood-vessels ;  that  this' 
3 8                      Psychiatry.
system  of cortical fibres passes into the  medullary substance of
the convolutions, and from there into that mass of internal white
substance (in each hemisphere) which is known as  the  centrum
semiovale of  Vieussens.   These  radiating  fibres  extend  ap-
parently quite to the surface of the hemisphere ; such at least we
should judge to be the casejrom an inspection of the many torn
sections of convolutions in figures 18, 20, 21.  The cortex exhibits
on the convexity of each convolution the shape of an inverted [\,
which  is changed in  the next adjoining  fissure to an  upright
U (top and  bottom  of the  cortical wave').   Cleavage of  the
cortex  from  the top  of the  inverted [\ opens  up  the  sub-
stance of the  hemisphere in a direction parallel  to the radial
fibres.   Secondly, in separating the cortical substance of any con-
volution from its adjoining white substance, we discover another
set of medullary fibres taking a very different direction from those
previously mentioned ; these  are  the  arciform fibres,  or  fibrae
propriae of the  cortex.   If  we attempt to dissect away the  gray
substance alone from the bottom of a fissure, and to remove the U-
shaped mass, we obtain a smooth surface which it would be  quite
impossible to get at the summit of a convolution, where the cor-
tical substance  is continuous with  the  radiating  fibres.  This
might  lead one to suppose that no radial  fibres start inward from
the bottom  of  a fissure ; but in reality this appearance is due
simply to the preponderance here of arciform fibres.
   The depressed surface of a cortical wave can be easily dissected
out as from a smooth medullary groove, which on closer inspection
is seen  to consist of  U-shaped medullary fibres.   These valleys
and fissures of the outermost medullary substance of the cortex,
which when  devoid of the  cortical gray are left wider than  the
fissures between the convolutions, resemble the half of a gun-bar-
rel constructed of wire rings. The smooth enucleation of the cor-
tex is possible in the longest fissures  and  in the shortest insular
formation ;  and can be equally well effected at every depth, and
whether the  fissures be  between primary, secondary, or tertiary
convolutions.   (Figs.  18-21 give a faithful representation of the
convolution  valleys and their vertical U-shaped cleavage sections.
Some of them are marked As—association fibres.)  These valleys
and  their U-shaped fibres are enclosed on both sides by radiating
bundles, but this mode of  dissection does not afford an insight
The original reads :
" Wellenberg und Wellenthal der Rinde."__S. 
Association Fibres of the Brain.
39
 into  the fine  network  of  fibres by means of which radiating
 fibres pass also into  the  narrow  cortex  at  the  bottom of  a
 fissure  (which Henle incorrectly denies).   On-the other hand,
 there is every evidence here of the part the U-shaped fibres take
 in the formation of the summit of a convolution.  The U-shaped
 bundles of the cortex do not necessarily extend simply from one
 convolution to the one next adjoining, but they may skip one, two,
 three, or an entire series of convolutions, and may thus join con-
 volutions which are united  among themselves to a convolution ly-
 ing  at  some distance from  these.   The shortest fibrce proprice lie
 nearest to the cortex ;  the longest  at the greatest depth, and are
 separated  from the cortex by other intervening fibrae propriae, the
 length  of which increases gradatim  from the  surface inward.
 The fibrce proprice or arciform fibres, must therefore be divided into
 short and long ones ; this  division answering  to a difference in
 shape,  for the shortest fibres alone present the U-shape, which
 results  from their close adaptation to the walls of a convolution
 depression.  While the long bundles take entirely different direc-
 tions, determined by the curvature of the surface of the fore-
 brain, and by  the longer or  shorter distance these fasciculi have to
 travel.
   The  fact of  greatest importance concerning the fibrae pro-
 priae  is  that  they begin and end  in  the "cortex.   The  direct
 opposite of these are those bundles of radiating fibres which take
 their origin in  the  cortex but  end  in some peripheral  gray
 substance, nearer to the nuclei of  the cerebral nerves, say, in
 one of the ganglionic masses at the  base of the brain.  These are
 not fibrce propria of the cortex ;  in their course they project the
 cortical surface upon every  imaginary or artificial plane situated
 below the fore-brain ; the higher the plane the more complete will
 this projection be.
   I  propose,  therefore, to call these bundles of fibres which origi-
 nate (but do not end) in the cortex, projection-fibres.  This name
 is justifiable even if we were to consider the course of these fibres
 in a  reverse direction.   Let us disregard for the moment all but
 the complete nervous organization of man.  The impressions of
the body are  conveyed to  the brain by the ramifications of all
the nerves and their terminal organs;  mutatis mutandis we may
argue that the cerebral cortex is the  surface upon which the entire
body is  projected by means of these nerves.
   It is a difficult matter  to  make an appropriate  subdivision 
40                        Psychiatry.
of these intra-cortical  fasciculi.   The masses  of fibrae  propriae,
which take an arched course, are distinctly limited on their concave
surface, but  their convex  surfaces are  connected  indirectly by
means of  graded  tangential fibres from the convexity of shorter
arches  with  the  investitures  of  the   convolution  depressions.
Keeping these restrictions in mind, we may distinguish  and shall.
describe the following  special formations :  a. The medullary sub-
                               Fig. 18.

Dissection of the Cortex and the M edullary Substance of the Median Surface of the Brain.
    Fr., Tp., Occ.  Frontal, temp., and occip. region.    Tr. Corp. callosum (trabs
cerebri),  c.  c. Cingulum.  As. Fibrae propriae (association fibres).   R. Cortex,   bi.
Fasciculus basalis internus (Burdach).   Li. Fasciculus longitudinalis inferior.  Olf.
Olfactory lobe.   La. Lamina perforata anterior,  ca. Anterior commissure,  unc
Uncus.  Sp.  Septum pellucidum.  Th. Optic thalamus, fd.  Descending fornix.
m. Corpus mammillare.  fa. Ascending  fornix.   Q. Corp.  quadrigemina.   A.
Aquaeductus Sylvii.   Pv. Pulvinar thalami.  Gi. Internal geniculate body.  T. Teg-
mentum.  Pd. Pes pedunculi cerebri.  St.i.  Stilus intern, thalami optici.   Lp.
Posterior longitudinal fasciculus.   Above pco.,  descent  of post, commissure,   co.
Conarium.

stance  of the cingulum (Burdach);  b. Fasciculus arcuatus  (Bur-

dach, Arnold);  and c.  Fasciculus uncinatus.

    The cingulum  (Fig.  18, c.)  surrounds the corpus callosum.

Above it lies a broad groove, due to the removal of  the calloso-

marginal  fissure.   The medullary  investment  of this  fissure is

contiguous with the cingulum throughout its course, as an inspec-

tion of the frontal  end clearly shows.  The same is the case with 
Association Fibres.                   41
the  fasciculi  proprii of  the  gyrus fornicatus which  cover the
cingulum, and is true also of the superior frontal and parietal con-
volutions surrounding this gyrus.
    Arnold  recognizes a fusion  of  the gyrus  uncinatus with the
convolution of  the cingulum ;  if we grant  this we must also
allow a similar continuity of tissue to exist with  the superficial
medullary bundles  of the marginal  convolution.   The  lowest
fasciculus of the cingulum adjoining the corp.  callos., the nerve of
Lancisi, whose  relation to the medullary substance of the cortex
was alluded to  on  p. 21  connects the cornu ammonis with the
olfactory lobe by a circuitous route.
    The cingulum accompanies, as it were, the calloso-marginal de-
pression ; it is the means of uniting  successively all the indirect
(short) and direct (long) cortical connections ;  and after effecting
this its fibres pass underneath the splenium of the  corp. callos. and
join (superiorly) the fasciculi proprii., on which the deep depression
of the occipital fissure of the sulcus calcarinus with its medullary
arches had  rested.   These medullary arches connect the cingulum
with the gyrus glossiformis.
    The posterior half  of  the  upper  occipito-temporal  fissure
exhibits after removal of the cortex a  depression formed by
arches which pass from the gyrus glossiformis  into the gyrus fusi-
formis.  In the anterior half of the same depression we find fibrce
proprice connecting  the uncinate with the fusiform convolution.
In  this  instance the upper branch of the U-shaped bundles, de-
scending from above, attains to a considerable length, for their
fibres originate in the  medullary substance of the cingulum.  The
fasciculus basalis internus of Burdach, which  a process of  lateral
exfoliation  has reduced to a narrow  medullary layer, lies  in the
axis of the gyrus glossiformis (Fig. 18, bi.), tends toward the gyrus
uncinatus, and  seems to consist of naught but arched  bundles.
The medullary band of the gyrus  fusiformis, the lower longitudi-
nal  fasciculus, so-called because it can be separated into long-
extended arched bundles, contains fasciculi which take either a
longitudinal or transverse direction, and which, with the various-
sized fellow-bundles of the third temporal convolution, form the
floor of the depression in which  the inferior occipito-temporal
convolution  is bedded.  Later  on we shall  see, too, that the
<ryrus  fusiformis receives distinct  portions  of the  projection-
system.   Furthermore,  Arnold knew  long   since   that   fibres
from the cortex of  the gyrus fornicatus pass into the  fornix after 
42                       Psychiatry.
traversing the corpus callosum.  These fibres also join the septum
pellucidum.   We may therefore conclude  that not  only  the
gyrus uncinatus but other convolutions despatch  their projection-
bundles through the fornix of the median surface.
   Tearing asunder the convolutions of  the  convexity of  the
brain, we discover, beneath the ordinary fissures, depressions lined
with arched bundles.  Anteriorly the temporal and frontal ends of
the hemisphere approach each other so closely, that the medullary
fibres connecting these lobes describe as  short  an  arc  as those
fibres do which combine any two ordinary convolutions.   Because
of this  sharp curve,  this bundle of  fibres has been called fas-
ciculus uncinatus.   It is evident, however, that only the frontmost
fibrae propriae bordering upon  the fossa Sylvii  describe such a
sharp curve.   The further apart the regions are which are united
by way of  the fossa Sylvii, the flatter the  connecting arches will
be.   Further back there are straight, long-stretched bundles  con-
necting the frontal and temporal lobes, and some even describing
an arc  the opposite  of that  described  by the gyrus  uncinatus.
These bundles, belonging  to  the  medullary  substance of  the
island (which contains to all appearances  fibrae  propriae only) and
crossing the claustrum, form a complete covering for the external
capsule, which in turn is  superimposed upon the smooth surface
of the lenticular  nucleus (Fig.  19, f.unc,  n. 1.).  While the  fas-
ciculus uncinatus  and the adjoining fibrae propriae of the  Sylvian
fossa are contained within the  region of the lenticular nucleus,
the  nucleus  lent., together  with the radiations of  the corona
radiata, are surrounded by the fasciculus arcuatus.  This mass of
fibres can be made to attain to any size, varying with the depth to
which  the  parts  have been separated.   About the Sylvian fossa
the fasciculus arcuatus is certainly well defined.
   In the parietal region, underneath the operculum, the fascicu-
lus  arcuatus is most strongly developed.   Anteriorly its super-
ficial  strata  are  continued  into the convolutions of the  oper-
culum.  In bending  downward  toward  the  temporal  lobe, its
superficial  bundles  can be seen entering the superior temporal
convolution, the parallel fissure,  and the  second temporal convo-
lution.  The deeper bundles of the fasciculus arcuatus spread to
the more distant convolutions of the entire convexity.  From the
general presence  and the  increase  in  length  (as  we  proceed
inward) of  these arched fibres, we gain the conviction that all the
convolutions of the median and convex surfaces of the fore-brain 
Association Fibres.                   43
form the closest  and yet most varied connections  one with the
other.
   The arciform bundles of  each hemisphere constitute an  ana-
tomical connection between various convolutions, which are sepa-
rated by  fissures.  These bundles are deservedly termed " associ-
ation-bundles."   They represent the union of the various divisions
of the fore-brain, to which alone  these  fibres belong, just as the
projection-fibres, which are to be found everywhere in the cortex,
represent the various organs and  surfaces of the body to which
these fibres extend through  their prolongations,—the peripheral
nerve-tracts.
   Dissection of Cortex and Medullary Substance of the Convexity of the Brain.
   n. 1. Lenticular nucleus,  f.unc Fasciculus uncinatus.  f.arc.  Fasciculus arcu-
atus.  cr. Corona radiata, projection-system.
    The corpus  callosum,  and, in man, the  greater part of the
 anterior commissure, form a system of fibrae propriae connecting
 both halves of the fore-brain.   This transverse system of fibres is
 distinguished from the association-bundles by the fact that it unites
 identical parts of the two hemispheres, and not different parts  of
 the same hemisphere.   The fibres of this system interlace on their
 way  to the cerebral convolutions with the projection-fibres, and
 through these with the intra-cortical fibres.   The corpus callosum
.forms the anterior and superior wall of the fore-brain (Figs. 5 and
 6), and its bundles  there  enter the medullary substance of the 
44                       Psychiatry.
frontal and parietal lobes.   But the splenium corporis callosi is a
double laminated structure, inasmuch as the posterior portion of its
longitudinal axis turns  downward  to become the lower surface
of the hindermost portion of the corpus callosum.  The occipital
bundles which leave this curved structure are not lost at once in
the projection-system,  but continue on  their  own course, quite
separate and  separable, toward the apex of the occiput.  These
occipital fibres of the corpus callosum take the same  U-shaped
course pursued by all  commissural  fibres from  one hemisphere
to the  other.   This  |D has been  likened to a forceps, forceps
corporis callosi.  The  two  lamince which make up the splenium
diverge on their way to the temporal lobe ;  they are separated by
the ependyma, and while the one passes to the cavity of the pos-
fibres.  T.2, T.3 Second and third temporal convolutions.
terior horn, the other extends to that of the inferior horn.  They
form  at the same time  the innermost medullary  stratum  of
these horns, the  inferior lamina of the splenium becoming  the
median wall, and the superior, the external wall of these horns. The
external lamina of the corp. callosum, the tapctum Reilii, lies partly
behind and partly around the thalamus, on the projection-bundles
(Fig.  21).  At the  posterior cornu we meet the following parts 
Association Fibres.
45
in due succession  from  below  outward: i. The cortex  and the
medullary substance between  the cingulum  and the  gyrus fusi-
formis.  2. The  fibres  of the  inferior lamina of  the splenium.
3. Ependyma.  4.  Ventricle.   5. Ependyma.  6.  Tapetum.   7.
Projection-bundles.
    The lateral portions of the  anterior commissure  are  lodged
in a  groove  on the  basilar surface of the lenticular nucleus, and
are in no way connected with the external capsule.  This nucleus
is surrounded by the fibres of the projection-systems, and is cov-
ered  on the outside by the capsula externa which emanates from
                               Fig. 21.
Dissection of  the Cortex  and Medullary Substance Starting from the  Median
                           Cerebral Surface.
    Fr., Tp. As before.  Occ.  Occipital region, in front of it the fasciculi occipito-
thalami'c'i.  ne. Remains of the  nucleus caudatus which has been partly enucleated.
Th. Thalamus opticus. P. Projection-bundle, fc. Fasciculi fronto-caudato-thalamici.
Z  Stratum zonale thalami.   c.  Anterior commissure.  ap. Ansa peduncularis.   L.
corp quadrigem. S. Aqused. Sylvii. Q. Fasciculus longitudinal, post.  Tg. Tegmentum.
f. Fasciculi temporo-thalamici.  P. Pes pedunculi.  r. Fibrae rectse mediales pedun-
culi. A. Amygdala,  o. Fasciculi frontales subependymiales.
the corona  radiata, and whose  medullary fibres converge toward
the base of the brain. The fibres are continued into the ansa pedun-
cularis, but this course cannot easily  be made out until  after the
removal of the anterior commissure.  Behind  and below in the di-
rection of  the cortex  the radiating fibres of  the  external capsule 
46                        Psychiatry.
are covered by the ramifications of the anterior commissure.  The
ramifications of the anterior commissure  extend  chiefly in the
direction toward the occipital and toward the temporal lobe, and
indeed along the entire breadth of  the latter (Fig. 20, Ca.).  The
parietal  and frontal  lobes  have no direct  connections with  the
anterior commissure.  But its  connections  with  the olfactory-
lobe shall  be referred  to later on  (p. 72).   The middle portion
of the anterior commissure, together with its relations to the ex-
ternal capsule, upon the outer surface of which  it abuts, are dis-
tinctly shown on Fig. 22 (ca. caps. ext.).  The sledge-shaped  me-
dian portion was excavated from out of  the  mass  of  the corpus
striatum above the lamina  perforata anterior.
    Continuing this demonstration of cerebral structure, by starting
from the median surface and dissecting away as  much as  possible
of  the  mass of the  corp.  callosum until the projection-systems
are distinctly visible, we can observe the projection-fibres radiat-
ing from all the lobes of  the  hemisphere  toward  the lenticular
nucleus  as toward a  common  focus.   Preparing a specimen in
this way, by starting from the median surface of  the hemispheres,
we must also  remove  the  gyrus fornicatus before removing the
corpus callosum.   After removing  the  gyrus uncinatus we leave
the amygdala intact about two centimetres  behind the  apex of
the temporal lobe.  In spite of the part the amygdala  takes in
the apparent flexion of the gyrus uncinatus, it is in no wise con-
nected  with the cornu ammonis,  but presents  toward it, as  its
posterior surface, a free anterior wall of the inferior horn  covered
with an ependymal layer (Fig. 21, A).
    The  task of tracing the projection-bundles to their termini is
rendered difficult  chiefly by the remnants of fibrae propriae  near
the cortex, but also  by fissures, grooves, holes,  and torn  parts of
bundles which result from the interlacing of the corpus callosum
with  the projection-system. The  radiations  of the  projection-
fibres from the cortex into  the thalamus are quite manifold.   To
perceive this distinctly, we  must remove the caudate nucleus and
the stria cornea.
   The tail of the  caudate nucleus extends as far as the  amygdala.  The bundles
of  the stria cornea arise from the summit of the temporal lobe and traverse  the
amygdala before entering the  nucleus caudatus, which is developed along  the  entire
inner-margin of the amygdala.
   Bundles of fibres from the cortex to the optic thalamus are mixed with lines of gray
substance even after the enucleation  of the nucleus caudatus,  for coalescent fibres of the
nucleus caudatus and the lenticular nucleus pass through the  capsula interna which 
Fibrillary Structure of the Brain.          47
separates  the two ganglia just mentioned (Comp. Fig. 6 with Fig. 27).  These anas-
tomoses of gray substance between both ganglia give a comb-shaped appearance to the
corona radiata (Reil).

   Over the denuded surface of the corpus  striatum projection-
bundles pass into the stratum zonale (Fig. 21, Z.) of the optic thala-
mus.  The frontmost radiations from the frontal lobe to the thala-
mus are covered  at their point of entrance into the latter by that
portion of the stratum zonale which emerges from the ansa peduncu-
laris, passes in a  transverse direction across the basilar surface of
the  crus  cerebri, and  is  recruited chiefly  from  the  temporal
lobe, joining finally the anterior end of the thalamus,(Fig.  21,
ap.).  The bundles from the frontal lobe, and more particularly the
superficial groups, evidently do not take the shortest route to the
stratum zonale of   the  thalamus, but  take a more longitudinal
course,  and travel  either  through  the  corpus striatum (Fig. 21,
ne.)  or along its outer margin (Fig.  21, o.).   The corpus striatum,
being the lower wall of  the anterior horn does not, as is the case
in the  primate brain (Fig. 6), abut upon the lower surface of  the
corpus callosum,  which constitutes the upper wall of the anterior
horn.   To the outer side of the corpus striatum or its denuded
surface  (Fig. 21),  we observe the .stunted vertical outer wall of the
anterior horn.  After removing its ependyma this wall  is seen to
consist  of longitudinal  bundles' which  arise from the  vertical
surface  of the frontal lobe, and passing to the outer side of  the
corp. striatum are merged in part behind the middle of  the optic
thalamus with its  stratum  zonale.   We  infer  from   this  that
projection-bundles  connect  the  frontal  lobe  with posterior por-
tions of the brain;  the  thalamus, for instance.   Behind this  for-
mation  radiating bundles of fibres connect with deep layers of the
thalamus, and form a true corona radiata.
   Vieussens  applied to all  these bundles surrounding  the  thala-
mus, the name " large radiating sun " (grandsoldi rayonnant) • but,
as we have seen, the course of these fibres is, by no means, en-
tirely radial.   From  the  anterior  portion of the  temporal lobe
radiating fibres start, which curve around  the outer side of  the
amvgdala to form a stratum zonale about the posterior  surface of
the optic  thalamus (straight temporal bundles T.). Other bundles
pass  from the occipital  lobe toward the optic  thalamus ;  these
bundles are finally lost in its deeper strata after taking a straight,
upward course beneath  the posterior stratum zonale just referred
to.   Below  the parietal radial projections, and to the outside of 
48
Psychiatry.
the corpus callosum these bundles form a medullary wall extend-
ing far below the thalamus, and presenting a basilar  area parallel
to the  entire  occipito-temporal surface.   The breadth  of  these
bundles seems to correspond to the region of the gyrus fusiformis.
Those bundles which originate in this or in  the third  temporal
convolution do not radiate  toward the thalamus, but run parallel
to the  basilar cortical  surface, whence they curve  toward  the
vertex of  the  temporal  lobe.  Behind  the amygdala,  however,
which the lowest bundles of this  group almost touch, the entire
group of fibres curves  upward,  forming parabolic  arcades,  di-
rected forward, and finally joining the thalamus below the stratum
zonale.
   I  have proved by careful  investigations that these arcades cannot  possibly be
due to the interlacing of the tapetum with  projection-bundles.  Judging by appear-
ances, we should say that at the summit of each arch-shaped projection-bundle, just
before its entrance into the thalamus, temporal and occipital fasciculi merge into one
another, the occipital fasciculi turning back in the direction of the temporal fasciculi.
   Gratiolet has given  a more summary account  of this com-
plicated  medullary wall in  the  baboon, and  has termed  these
bundles  optic radiations.
   He proceeded on the supposition that they emanated directly from the tractus
opticus, but the latter's stock of fibres would be manifestly insufficient. Gratiolet
also describes them as extending largely into the cortex of the parietal lobe.
   From the  anatomical point of view,  this  medullary stratum
deserves the designation optic radiations, for  radiating fibres pass
from it  into  all  the termini of  the  optic tract (corpora quadri-
gemina, corp. geniculatum—Fig. 5, Om.).  The stratum zonale of
the pulvinar, which is connected with the optic  tract,  takes its
origin from  the  posterior superficial strata of the  thalamus, in
which strata the fasciculi temporo-thalamici (T.) disappear. Arnold
was the first to entertain this view.
   It suffices  for our  purposes to have demonstrated, by means
of this one example, the manifold formations of the projection-
system within the white  substance of the hemispheres.  We meet
with  the projection-system again  in a dissection inward  from the
convex surface of the fore-brain  ; apparently the outermost  dis-
tinct  layer of the projection-system is made up of radiating fibres
passing into the lenticular nucleus and its external capsule (Figs.
19 and 20).
   Pushing this same method of  dissection still further, we  gain
important  information  regarding the brain  isthmus (Fig.  22). 
Architecture of the Brain.              49
Taking the  methodically prepared (enucleated) brain-axis,  the
outer portion of which includes the formations of the fore-brain
covered by the cortex of the  island of Reil (lobus caudicis—
Burdach),  we  intend  to enumerate those  strata which are de-
veloped from the basilar surface of the brain.
   The right half  of  the adjoining drawing (Fig. 22) represents
the superficial strata on the basilar surface  of the  lobus  caudicis
(Stammlappen), beginning with the external  capsule of  the len-
ticular nucleus, while  the  thalam- and mes-encephalon have been
ived, or at least such portions of  them as are included in the
Inar.'corpus geniculatum, and tractus opticus, which covered the 
5o
Psychiatry.
basilar (Fig. 15) and posterior (Fig. 17) surfaces of the crus cerebri.
This figure enables us to continue  with the enumeration of the
occipital and temporal strata as given on p. 45.
   The external capsule covers the lenticular nucleus  with radi-
ating fibres, whose focal point  is screened  by the anterior com-
missure.  These  fibres pass  to the  ansa peduncular is.x  Of this
complicated structure (vide Figs. 6 and 21) we shall simply remark
that its strata cross the  pedunculus  cerebri  transversely.  Its
lowest stratum (Fig. 23, ans.2) forms  a part of the pes pedunculi.
The outermost bundles of the pes pedunculi, and particularly the
posterior bundles, are developed from a fan-shaped group of bun-
dles (Tm.) arising  from the  temporal  and occipital lobes.  The
parietal  flexure changes these posterior  into  superior bundles
(Fig. 17, Pd.).   The optic radiating fibres, which have been  re-
moved  together  with the pulvinar and corp. geniculata, lay im-
mediately adjoining this fan-shaped  group of fibres.  The former
constituted the seventh stratum  of the temporo-occipital lobe.
The above-named  peduncular radiations  from the eighth and the
neighboring occipito-temporal radiations of the anterior commis-
sure (Figs. 20 and 22, ca.)  form  the  ninth  of  the enumerated
strata.  [As for the temporal lobe, a tenth  stratum would join it
from the temporal lobe.]
   Removal of the superficial groups  of transverse fibres of the
pons reveals the anterior longitudinal bundles of the pons  as the
direct connections  between the  pedunculus cerebri and the pyra-
mids of the oblongata.

   Fig. 22 (between Pd. and O.) shows a common variation from the  regular typi-
cal course which these  fibres take  in different  brains.  An anterior bundle  of
fibres of the pes pedunculi seems with its narrowed lower end to join the  olivary body ;
this isolated anterior bundle probably rejoins the remaining pyramidal fibres.

   The pyramidal  tract can be subdivided into three distinct seg-
ments :  (1) fibres of the crus ;  (2) the anterior longitudinal bundles
of the  pons, and (3) the  pyramids of the  medulla  oblongata^
The fibres of the pyramidal tract then decussate and cross to the
opposite side of the spinal cord, or rather into the lateral column
of the opposite side.
   The pyramidal tract, which is strong by reason  of  a prepon-
derance of deep-seated bundles, forfeits more than two-thirds of
its sectional area while passing through the pons.   The  fibres thus
Hirnschenkelschlinge.
* Linsenkernschlinge. 
Architecture of the Brain.               51
lost  help to build up the pons by changing their direction and
congregating  into  transverse  bundles.  This anatomical nicety
cannot be demonstrated on gross anatomical preparations.   The
oval median section  of  the  deep  transverse fibres of  the  pons
seems chiefly to be a commissure of those medullary layers which
start from the  cerebellar cortex, and unite in the brachium pontis
(process, cerebelli ad pontem,  Fig. 22,  f.p.).
   The fasciculi of the brachium pontis lie in the cerebellum in a strict order of  suc-
cession, where we  can observe distinctly their origin from the ramified ribs  of the
leaves of the arbor vita and also the sections of the delicately foliated fibrae propriae
of the cerebellar medullary substance (Stilling's wreaths).
    Before removing  the  pes  pedunculi we must detach the ansa
lenticularis (Fig. 23, ans.), which takes its origin in the  lenticular
nucleus and joins the innermost bundles of the  crus.
    By detaching  upward the remaining peduncular fibres of  the
crus, we loosen the lenticular nucleus and a considerable  portion
of  the  internal capsule,  which in part descend from the cerebral
cortex through the pes pedunculi.  Behind  this surface  we  dis-
cover  still  another cortical stratum of the  internal capsule, con-
sisting  of radiating  fibres intersected by fibres from other strata ;
the former do not extend over the  entire  breadth  of the corona
radiata (Fig. 22, caps. int. to Tg.  These fibres  do not  extend as
far to the outside as they are here  represented).
    At  the point at  which the  bundles of the internal  capsule
course at the same level with the pes pedunculi of the opposite
side, these bundles mix with the substantia nigra of Soemmering,
and with this  black substance are fused into a very compact layer
of the crus behind the superficial strata (Fig. 22, Tg.).   This stra-
tum intermedium pedunculi, as I have named it, which covers  the
tegmentum of the crus, shows in that area a convex bulging due
to  the red nucleus lying behind it.   Further on  this stratum inter-
medium pedunculi presents a concave surface  resting  upon  the
deep transverse  fibres  of  the  pons, and in the  oblongata this
stratum appears  to  develop  into  the  foremost fibres of the an-
terior column lying behind the pyramids and to the inside of  the
olivary  body.   In a  median direction from the  fifth nerve,  a
narrow bundle of fibres, broadening above, joins the peduncular
stratum intermedium; this bundle  lies to the outside and separate
from it, wending its  way as the fillet from  the posterior surface of
the brain-axis across the superior  peduncles of the cerebellum to
the anterior surface  (Fig. 22,  L., Pr.)  The lemniscus originates in 
5 2                            Psychiatry.
the corp.  quadrig.  (Fig.  17);  it  undoubtedly gives off  bundles
which coalesce intimately with the olivary body (Burdach, Arnold).
If  the cerebellum (Fig. 22, left R.) be denuded  of all pons fibres,
we discover a cerebellar strand which tapers toward the  oblongata
and enters into the  restiform body.
  Deeper Dissection of Brain Isthmus and Cerebellum Viewed from Basilar Surface.

    Nc. Caudate nucleus.   II. Optic chiasm.   I. Infundibulum.  m.  Corpus mam-
millare.   P.  Posterior perforated lamina,  ans. Ansa peduncularis, between  the ex-
ternal capsule of the lenticular nucleus and the pes ped.   (Pd.) caps.  i. Occipital
bundles of the pes ped.   St. Medullary stratum, together with Soemmering's substance,
covered  by cross-section of the pes.   N.R.  Red nucleus of the tegmentum,  x.
Decussation of the superior cerebellar peduncles, horse-shoe shaped  commissure of
Wernekinck, extending on the right  to the exposed  internal  capsule.   L. Medullary
layers. J. Tegmentum. Fr. Torn fibrae rectaeof the pons, lying between deeper layers
of tegmental bundles or  their prolongation in the pons.  Gi. Internal geniculate body.
e. External geniculate body.  Th. Pulvinar of thalamus.  Pr. Superior cerebellar pe-
duncles.  Nd. Dentate nucleus of cerebellum.   R. Corpus restiforme.  Cbl. Cerebel-
lum.  Fl.  Flocculus.  V.  Trigeminal.  VIII. Eighth nerve.  O. Olive, connected
on the right side with a  deep fasciculus coming from the posterior division of the pons
(tegmentum),  fa.  Anterior column {funiculus anterior),  fl.  Lateral column {funi-
culus lateralis).

    Note.—Figs.  22 and 23 present in their several halves four different levels and
four different strata : 1. Fig. 22 (right side) throughout  its  entire length shows the
most basilar strata ;  2.  Fig. 23 exhibits on the left as far as St. the next more superfi-
cial strata of the fore-brain ; 3. Fig. 22, left side, exhibits, with exception of the pul-
vinar, a deeper stratum  than the right side of Fig. 22, and a  more superficial  stratum
than the remainder of Fig. 23, left side, and Fig. 23, right side. 
Structure of the Brain-Axis.
53
   The brachia pontis' are regularly stratified masses ;  the corpus
restiforme, on the other hand, is a distinctly foliated medullary
structure  covering a convex  body  the outlines of which can be
readily  discerned.   This convex body is the dentate  nucleus of
the cerebellum (Figs. 22 and 23, left side, R, right side, Nd.).
   The red nucleus is exposed to view by a transverse division of
the fibres of the pes ped. and of all longitudinal fibres of the stratum
intermedium, and of Scemmering's substance, just above the corp.
quadrigemina (Fig.  23, Pd., St.), sections of the latter  resembling
two concentric crescents.  The nucleus ruber  is the ganglion
of the superior cerebellar peduncles (Fig. 23, N.R.).  These deep-
seated structures in both halves of the tegmentum seem to be con-
nected  by  a  transverse  horse-shoe  commissure  (according to
Wernekinck).   Stilling proved this commissure to be the decus-
sation of the processus cerebelli ad cerebrum? which  arise from the
red nuclei.  In consequence of the  density of its foliated mass the
surface  of the nucleus ruber appears smooth (Fig. 23, left). Above
and to the outer side, the red nucleus becomes considerably attenu-
ated, and connects with that portion  of  the corona radiata which
courses immediately beneath the  optic  thalamus (Fig. 23,  right,
caps. int.).    Viewed as a ganglion, the nucleus ruber represents
a  shell-shaped plate, thickened  on  its  lower inner  surfaces.
A group of bundles takes a spiral course over the basilar sur-
face of  the red nucleus and adheres closely to it.   It  is possible
that these fibres upon the lower surface of the nucleus ruber rep-
resent an uncrossed transition from the internal capsule to the pos-
terior surface of the superior cerebellar peduncles (Fig 23, right side).
    Before reaching those fibres which radiate from the internal
capsule and pass into the nucleus ruber, as represented in the fig-
ure, we come upon  layers of  the internal capsule which pass into
a  bulging ganglionic  mass  immediately  above  the  substantia
Soemmeringi. Forel has given the most accurate  description of
this discus  lentiformis.  The foliated structure of this ganglion
is intersected by transverse medullary fibres in a direction vertical
to  the  bundles  of the capsule.   This  formation provides the
nucleus ruber on its upper and outer side with a  plastic promi-
nence which is well seen after removing the substantia nigra. Stil-
ling discovered the connection of  this ganglion with the  optic
tract.   This lentiform body  is exhibited on longitudinal sections

    1 Processus cerebelli ad pontem ; medipedunculi (Wilder).—S.
    2 Praepedunculi (Wilder).—S. 
54
Psychiatry.
in Figs. 33  and 36,  and on  cross-sections in Fig. 34—all  being
taken from the human brain.
   Besides separating the  lemniscus from the processus ad cere-
brum and detaching the pons-fibres which cover the basilar surface
of the latter, we must  also remove the corpus restiforme in the
cerebellum and the ependyma of the anterior cerebellar surface, if
we wish to get a full view of  this superior cerebellar peduncle.
Arising from the opposite nucleus ruber (Fig. 23, N.R., left) it
passes through the decussation-elevation (Fig. 23,  x.), and on  the
other side dorsad of the trigeminal root (Fig. 23, right, V.) into the
cerebellum, where it disappears in the nucleus dentatus cerebelli
(Fig. 23, Nd.).  Inasmuch as this dentate nucleus is connected by
medullary fibres with the cerebellar cortex, we may regard  the
decussated fibres of the processus cerebelli ad cerebrum as extend-
ing from the cerebral cortex of one hemisphere to the cerebellar cor-
tex of the opposite side.
   The brain-axis reveals the following formations  connecting the
crus with the spinal cord : (1)  The ansa nuclei lenticularis. (2) The
pyramidal tract discussed above. (3) The stratum intermedium with
Soemmering's substance.  The fibres of the intermediate stratum
abut dorsad upon the pes ped. as far as  the  pons.   Its anterior
portion consists of bundles which  simply pass over Soemmering's
substance but (and this is quite remarkable) are in no wise connected
with the origin of the tegmentum.  The stratum  intermedium is
developed from the fore-brain ;  all the bundles of the tegmentum,
however, come from the inter- and mid-brain.   The layer of bun-
dles belonging to the substantia  nigra joins the posterior tract of the
isthmus within the pons, and takes no part in the decussation of the
pyramids.  Without recognizing its relation to Soemmering's sub-
stances, Stilling has  spoken of  a  posterior layer of the pes pass-
ing into the posterior division of the pons.  According to Burdach
and Clarke an undecussated portion of the pyramidal tract joins
the anterior  columns of the medulla oblongata.   This can  not
refer  to  any others but the bundles of Soemmering's substance,
which  lie immediately upon the pyramids, and  hold  the same
relation they held higher up to the pes ped.  The anterior columns
lie behind the pyramids, and both contain non-decussating fibres;
a dissection of  the posterior pyramidal fibres  will, therefore, lead
into the anterior columns.  The name given above to this  nerve-
tract applied only to that part of it in front of the mid-brain in the
cerebral peduncle, and not to the entire tract ; to that part of the 
Stratum Intermedium.
55
pyramidal tract which does not properly belong either to the an-
terior or posterior tracts of the brain-axis I would give the name
stratum intermedium caudicis.   It  requires no  further proof that
if  the median furrow is bounded by the anterior  tract of the
isthmus—by the pyramids,—the stratum intermedium, as Clarke
describes it, must be situated  behind  the pyramids.   Below the
pyramids the anterior column apparently forms the median fissure.
The anterior columns develop median surfaces simply by pushing
their formerly anterior surfaces (strata intermedia) inward toward
the median line, approaching it more closely as the  decussating
pyramids pass outward and leave a free space between them ; the
anterior columns first approach each other at an angle which is open
anteriorly, but finally they  oppose their  median surfaces to each
other along  the anterior median  fissure.  For purely anatomical
reasons, therefore,  we  find  that  the stratum  intermedium is
continued to and on  the inner surface  of the anterior columns
of the  spinal  cord.   Tiirck and  Flechsig  have  reached the
same  conclusion  from  pathological and genetic investigations.
(4) After dissecting away the stratum intermedium, the tegmen-
tum comes into view.   Its most anterior layer of fibres belongs to
the lemniscus, which, together with some fibres of the optic thal-
amus, covers the processus cerebelli ad cerebrum, behind which the
deeper longitudinal bundles  of the tegmentum descend on their
way through the pons to the antero-lateral column of the oblongata
and spinal cord.   One of the  bundles of the tegmentum (Fig. 23,
right) would seem to be  a tme funiculus olivaris.  The dissection
of these bundles gives no artificial, but  an incomplete, notion of
the complicated structure of the posterior division of the cerebral
axis. 
   THE  MINUTE  ANATOMY  OF THE  BRAIN.

                        THE CORTEX.

   The  cortical  tissue of the  hemispheres varies in different
regions as regards the shape, size, and distribution of its nervous
elements, while the basis substance remains the same throughout.
We are justified in applying to the non-nervous basis substance the
very fit remark of Reichert, in regard to the body tissue in general,
and in arguing that the brain consists of a mass of connective tissue,
in which the parts characteristic of the brain, the nerve ganglia and
their processes, as well as the  nerve  fibres, are  imbedded.  That
the  existence  of basement substance in the  cortex  is entirely
independent of nervous  elements is proved  by  the fact  that
the mere presence of nerve cells with numerous processes does
not give the appearance of gray substance.   We find dense rows
of ganglionic cells in various parts of the brain, in the medullary
substance which  borders upon the  cortex, in  the medullary sub-
stance of the island of Reil, in the external capsule of the len-
ticular nucleus, in the nucleus dentatus cerebelli (Stilling), and,
according to Boll, throughout the white substance of the brain;
and yet the characteristic features of the medullary substance are
in no way effaced by these cells.  In contrast to these formations,
others which contain but few nerve cells, the superficial strata of
the cortex (Rokitansky's ependymal formation, Virchow's neurog-
lia), for instance, present the appearance of gray substance.  The
volume of gray substance, furthermore, is not at all commensurate
with the  number of nerve cells and fibres in the brain ; it is more
abundant in the brains of animals than in that of man, and indeed
the  proportion of gray substance   increases  the more  remote
the brain type is from the human, and the greater the simplicity
of the cerebral surface.
   This argument is  best sustained by measurements which have
been  taken  of  the superficial strata of the cortex, containing but
very few  nervous elements, as compared with other regions which
have  an  abundance  of these elements.  These superficial strata
                             56 

V

                                    Fig. 24.
Section through the Third Longitudinal Convolution of the Frontal Lobe Adjoining
            a Fissure.   (The Five-Layer Type of the Cerebral Cortex.)
    I. Superficial layer of neuroglia.   2.  Layer of small pyramids.   3.  Layer^ of
large pyramids ('' formation of the cornu ammonis ").  4. The granular layer.   5
layer  of spindle-shaped cells ("claustral formation").  ™  M*>Hnllnrv snr
the convolution.
                                       57
                  The
Medullary substance of 
58
Psychiatry.
constitute in man but -fa-\ ; in smaller apes, \-\\  in the dog, \;
in the  cat, \\  in the bat, \;  in  the calf and  deer, \ of  the en-
tire breadth of cortex.   Their absolute  breadth  of 0.25  mm. in
man is exceeded by 0.4 in  the calf, and 0.5 mm. of this substance
in the  deer.
    This  gray  substance  between the nervous elements appears
under  the microscope  to  be made  up  of densely crowded dark
spots surrounded by tissue of a brighter color.   It contains  dis-
tinct connective-tissue elements, with a network of fibrils from the
processes of these elements, and a second network of fibres derived
from the  processes of the nerve-cells.  I learned as much as early
as  1870  from preparations hardened  in bichromate  of  potash,
stained with carmine, dehydrated, and rendered transparent by oil
of cloves  (Strieker's " Handbook of Histology ").   Further details
were recorded by Jastrowitz1 and Boll2 as a result of their methodi-
cal researches, and  it  was  shown to be  a far more complicated
structure.
    The following minute description of cortical gray substance applies to all gray sub-
stance, wherever found,  The cortical surface borders upon the pia mater.  There
is no epicortical lymphatic space,  as was proved by careful injections 3 of the lymphatics
of the pia mater.  The gray substance has a sort of  limiting membrane, consisting of
connective-tissue cells with numerous processes, which are quite the same as the con-
nective-tissue cells in the  gray substance.   Various  influences conspire to affect the
direction of these elements among the different tissue-structures, in  consequence  of
which we find the  processes from the outer cell-terminus spread flatly over the cortical
surface, while the pointed processes starting from the other end of the cells, take a
radiating course through the cortex.  These processes, according to Lowe, are 0.125
mm. long and ramified, and are not unlike the cone-fibres of the retina. The outermost
stratum of the cortex is, therefore, an epithelial arrangement of connective-tissue  cells,
whose individual form is best represented to the mind by the leaf of a palm-fan the
stalk of which is at right angles  to the leaf surface.   Fleischl described as the outer-
most cortical layer a fenestrated cuticula, which is  rendered visible  by staining the
cortical surface with silver; this  cuticula Boll considered to be an albuminous mem-
brane in the valleys between the very delicate  prominences  on  the cortex  caused  by
the flat connective-tissue cells.  Boll's "fusiform"4 cells are found, in lesser numbers
and without the palm-fan shape, everywhere in the gray substance.   These glia cells
(neuro-glia),  vary  in shape (according to Jastrowitz),  from spindle-shaped  cells—
resembling those of the tendons—to such as are surrounded by numerous fine (according
to Boll) non-ramified processes.  The size of the cells varies between 4-17 ^ (Jastrowitz).
The body of the cell is at times considerably developed, and then again it disappears

    1 Arch,  fur Psychiatrie und Nervenkrankheiten, vol. II., p. 389 ; vol. III.,  p.
162, 1870-71.
    '* The same, vol.  IV.,  p. 1,  1874.
    3 Experiments of Boll and Golgi.
    4 " Pinselzellen," " pencil-cells " would be more literal.—S.
    s fl = -j-gVff  millimetre—S. 
The  Cortex.
59
between the processes.  From specimens  obtained by teasing the preparations Boll
described the  protoplasm around the nucleus of the glia cells as a granular substance
without well-defined boundaries, lying between the extremely delicate pencil-shaped
fibres.  The second form of non-nervous elements of the gray substance are the glia-
nuclei, which  are connected with the granular basement substance.  They are more
numerous in the newly-born and densest in the cortical layers.  Their protoplasm can-
not be separated from the granular basement substance.  In the embryonic chick Boll
could not observe that early stage in which distinct embryonic cells hold the ground
occupied later on by the continuous basement substance, but he could notice that the
granulated  substance, consisting  of a protoplasmic  formation,  uniformly studded
with spherical dots, soon changes  its  appearance.  This change is effected  by a
twig-like grouping of adherent granules, which is particularly distinct in the vicinity of
the double-contoured nuclei, and converges slightly toward them.  This resembles a
formative activity of the cells.  "On the strength of these investigations it would,
perhaps, be fair to assume that in spite of the confluence of the cell-protoplasm, and
the fusion of the  cells proper, there exist virtually and physiologically separate cell
units."  The  nuclei once densely  crowded  move far  apart  in  consequence of  the
proliferation of the ground substance (increase of the granula—Boll). The granulated
substance is absolutely independent  of the nerve fiWrils,  or of connective-tissue fibrils,
but simply remains attached to these fibrils after teasing them (Jastrowitz,  Boll).  The
granulated basement substance is highly albuminous. Boll explains this'by saying that
the basement substance  is developed out of primary embryonic connective-tissue
cells, and that its quantity of albumen is similar to the granular albuminous material
which is formed everywhere with the development of the connective tissue in and next
to the nerve fibrils.  This albuminous material is stored sparsely in some and liberally
in other connective-tissue formations during the  entire period of life.   Jastrowitz
ascribes to the granulated substance  in the cortex the function of isolating nerve fibres,
for in the cerebral medullary substance the  axis-cylinders are separated from one
another by the same white substance before the latter is transformed into the medullary
sheath of the axis-cylinder.  The views of Besser,  Arndt, Rindfleisch, and Henle have
been disproved by the investigations of Jastrowitz and Boll.
    As I  stated in  1867, the nervous  elements  of  the gray  sub-
stance, form regular concentric layers,  the arrangement  of these
elements being modified  according to the locality in which  they
occur.
    The  commonest type of cortical stratification  is  found in all
the convolutions of the convexity.   A transverse section of the cor
tex presents on the whole  a uniformly gray appearance.  In the
middle of some of  the broader convolutions we find a less grayish
zone, due to  loss of pigment.   On transparent sections  of these
convolutions (magnified 100 diameters), we can distinguish  five
layers, the first being immediately  beneath the pia mater.
    The first layer  is made  up  chiefly  of the basis substance and
its connective-tissue elements.   The latter are most numerous near
the surface of  the  cortex.   A few irregular, angular cells are  seen
scattered throughout this  layer.  This is the neuroglia layer.  The
second layer is  sharply  defined on its outer margin,  and consists of 
60                      Psychiatry.
densely crowded pyramidal-shaped bodies, which turn their apices
toward  the  surface, and  measure about 10 ju. in  height.  The
internal boundary is also  well marked, owing not so much to a
change in the size of these nervous elements, as to the lesser den-
sity of distribution.  This is the layer of small pyramids.  In the
succeeding third layer,  a  distinct columnar  arrangement of the
nerve-cells, which are quite separate from one another  in a trans-
verse direction, may be  noted.   This is due largely to  the aggre-
gation of  nerve fibres  from the basilar  aspect of  the small
pyramids.  These nerve fibres  increase inwardly, and push their
way  in  between  groups of pyramids.   The  pyramids,  while  in-
creasing in  calibre, attain to a  height  of 40 jj. or even 60 //.
according to the width  of the  convolutions.  In addition to the
ramified apex-process, and from four to seven ramifying lateral
base-processes, there is  one median base-process (Fig.  24, lowest
row of layer 3), which runs in a diametrically opposite direction,
yet parallel to the apex-process, toward the medullary substance.
The  nuclei of the pyramids are miniature pyramids themselves,
their  angles often extending into the processes of the pyramids.
This  is the layer of large pyramids, or  at least the layer which
contains these.
   A sudden jump as regards calibre is made from these layers to
the fourth, composed of multiform elements, chiefly of a rounded-
angular nature.   This  is  called the "granule-like" or granular
formation.
   Between this layer and  the medullary substance of the convolu-
tion, we find a fifth layer  not definitely bounded, and consisting near
its outer margin of rather large but short pyramids. The further we
proceed  toward  the white substance, the  more spindle-shaped
nerve cells of about 30 7«w. we find ; these spindle-shaped cells,
sending processes toward the granule-layer, present the appearance
of vertically compressed  pyramids.   But they never  show any
thing in the least akin to a median base-process.
   The medullary substance constitutes the sixth layer of these con-
volutions.  This layer  contains a fair  number of spindle-shaped
nerve cells, taking the  same  direction which those of  the fifth
layer do.  The axis-cylinder, as well as the medullary  sheath,
varies very much in size, from the exceedingly delicate to the
dimensions of spinal-cord  fibres. The central fibres lack the mem-
brane of Schwann and Ranvier's internodia (Boll), which are char-
acteristic  features of the medullary substance in peripheral nerves. 
The Cortex.
61
   The white substance is studded with granules (cubic cells, Boll),
which  in  their arrangement (though  normally interrupted in the
adult brain) imitate the course which  nerve fibres take.
   In  the entire  cortex  there  are  but three  forms of  nerve
corpuscles: (i) the pyramidal form, (2) the granule (mixed) form
of small  nerve  cells,  and (3) the  spindle-shaped form.   In the
drawing (Fig. 24) the  first formation is  found in the second  and
third layers; the granules, in the fourth ; the spindle-shaped cells,
in the  fifth layer.   In Fig. 25 we  find the pyramids in the second
layer;  the granular elements in the second,  fifth,  and  seventh
layers  ; the spindle-shaped bodies in the eighth layer.  The pyrami-
dal and spindle-shaped  bodies differ from  each other chiefly in
regard to position.  The longitudinal axis of the pyramidal bodies
(parallel to each  other) stands vertical to the cortical surface, while
the longitudinal axis  of  the spindle-shaped  cells lies parallel to
the surface df the cortex.  Throughout the central nervous organ
a morphological law  evidently operates, by  reason  of which the
formative activity exercises an influence over the direction of the
nerve  cells, making the direction of  their longitudinal axes parallel
to that system of fibres which originates from them.
    Let us recall the various directions which the different systems
of cortical fibres take, and which were demonstrated by the prepa-
rations represented in Figs.  18 and 19.
    Obviously enough the direction of the pyramids (vertical to
the cortical surface) is parallel to the projection-system fibres,  and,
on the other hand, the fibrae propriae (of the association-system),
which do not conduct from or to the cortex, but  from cortex to
cortex, run parallel to the surface of  the convolutions, just as in
the above figures (24  and 25) the spindle-shaped cells lie parallel
to that surface.
    Although the spindle-shaped cells are  by no means bi-polar cells, and have un-
doubted lateral processes as  well, yet the latter run parallel to the surface, and, as they
are turned away from the medullary substance of the convolution, can form no im-
mediate connection with the projection-systems.
    We can  obtain double proof of  the parallelism existing be-
tween the axes of  spindle-shaped elements and the  fibrae propriae
by comparing a section of the cortex taken from the summit of a
convolution  with one (represented  in Figs. 24 and 25) taken from
the margin of a fissure.   The fibrae propriae  intersect'at the  mar-
gin  of a sulcus  with the projection-fibres (page 38), but  at the
apex  of  the convolution both systems of  fibres run parallel to 
62
Psychiatry.
 one another;  just so the spindle-shaped bodies of the fifth cortical
 layer, bordering upon a fissure, intersect with the pyramids of the
 second and third layer, but at the summit of a convolution the
 former lie vertical (radial) to the surface of the cortex and parallel
 to the axes of the pyramids.
    Henle is wrong in stating that the pyramids are absent in the cortical substance
 bordering upon a  fissure.
    The cortical nervous elements  can be distinctly made out in
 the  chick from the third day of development on, and very shortly
 after this the direction of their axes is apparent (Boll).  In  the
 human embryo both  these nerve-cells and their processes  show
 not  later than  the  fourth  month.  At this  period  there is very
 little basis substance  separating  them ;  as they are very dense
 at this  early stage it is probable that they do not go on increasing
 in number.  Their own  growth and  that of  the basis substance
 seem to be part and parcel of the growth of the cortex.
    Besser, Arndt, and Henle have expressed different views on this subject.
   All  cortical nerve corpuscles are composed of a sheathless pro-
 toplasmic  substance,  finely, but not always  equally, granulated.1
 According to  Reinisch and Max  Schulze, the protoplasm of the
 nerve cells has a striated appearance, which Boll has proved, in
 specimens stained  with  hyperosmic acid, to  be common also to
 the  pyramids of  the cortex.  The striations of the ganglionic
 processes have  been familiar to  us for some time.  These  pro-
 cesses are equivalent to the axis-cylinders of nerve fibres.   Because
 of these minute fibrils, the  ganglionic  process and  the  axis-
 cylinder are  supposed  to be not  morphological elements, but
 aggregations  (fasciculi)  of minute  fibrils;  these   fibrils  alone
 are  present in  the invertebrata, and for that  reason  are con-
 sidered the elementary nerve fibres.  These processes  and  axis-
 cylinders emanate  from the ganglion cells, in the protoplasm of
 which they appear to be scattered like the hairs of a brush ;  they
 pass from one process to the other, or tend toward the  nucleus,
 which seems to  be surrounded by such fibrils.   These fibrils  cross
each  other, interlace  closely with  one  another, and thus  lose
 their individuality.   Max  Schulze  was, perhaps, the  first to
suggest that a  ganglionic cell might possibly, from the  arrange-
ment of its fibrils, represent a plexus, and that the protoplasm
was simply traversed by afferent and efferent fibrils.
   1 This granulation causes a pigmentation of the protoplasm,
and distribution. 
The Cortex.
63
   Other authors have endeavored to prove that the nerve fibrils
do in reality  terminate in the granular basis substance, where,
according to Rindfleisch,1 the  " fibrillary "  and the " granular "
structures are fused.  Very soon afterward, Gerlach,2 after politely
saying that he would confirm this view, contradicts it, by showing (on
potassium and gold chloride preparations) that the ganglionic pro-
cesses, after ramifying minutely, send terminal fibrils into a general
network.   Prior to this, Jastrowitz stoutly maintained that when-
ever he detected fibrils covered by granular substance, the fibrillary
elements extended beyond the granular.  Boll declared that Rind-
fleisch's hyperosmic-acid method was the very one best adapted to
prove the independence of the finest fibrils  within the granular
substance.
   Those who attempt to divest the nerve cells of their importance
as centres, and who trace the anatomical origin of nerves to a dif-
fuse substance, such as the granular portion of the gray substance,
render it impossible to establish a relation between the anatomical
structure and  physiological function of  these  parts.  Strangely
enough, the ganglion cell with its ramified processes would be in
direct contrast to the spider in its web.   The active agent would
be, not in the spinning body but in  the meshes of the web.  Such
a  view of  the  anatomical  structure of  the nerve cell could un-
doubtedly be entertained, but it would then be impossible to con-
ceive of any physiological agent discriminating between two such
masses as the ganglion cell and the intercellular substance.   Even if
we were for the moment to lay aside  all justifiable  doubts as to
the striated appearance of the ganglionic bodies, the striae being de-
ceptive, due perhaps  to a mere folding, or to  the changed tension
of a body separated from its surroundings, to which its ramifications
had attached it;  discarding such doubts, I say, we can still find
good anatomical reasons which force us to regard  the nerve
corpuscles of the cortex, the pyramids for example, as independent
elements within the network of ganglion processes.
   1. From the time of the existence of formative cells in the an-
terior cerebral vesicle, the nerve cells are independent of the forma-
tion of the basis substance, and, as we learn from comparative
anatomy, the former is independent, throughout life, of the develop-
ment of the  latter; while, according to Boll, the fused  pro-
toplasm of  the basis  substance with its nuclei represents the
remnants of other cells.
   1 Centralblatt fur die medicinischen Wissenschaften, 1S72, page 77.
   ' Idem, 1S72, page 273. 
64                       Psychiatry.
   2. The processes start in the ganglionic cell, and are originally
nothing but a prolongation of the  cell protoplasm, granular and
non-striated, but undergoing later on numerous ramifications (Boll,
/. c, " Entwicklung des Huhnchens " ).   The cell processes perma-
nently retain their protoplasmic character, not only in continuity
with the protoplasm of  the ganglion, but also after the interrup-
tion of the granules at considerable distances from the ganglion, in
the midst of the fibrillary striation (Max Schulze).  From  the
very start the ganglion cell is an independent centre; the processes
and their ramifications are portions of the ganglionic body.   All
their parts  together form  the  protoplasmic individual.   The
striation would lie entirely within the latter, between  one process
and another.
   3. The axis-cylinder develops out of special spindle-shaped cells
in the medullary region  (Boll), the protoplasm of which is con-
tinued into  the gray substance of the cortex,  and there  splits up
into  very delicate fibrils;  on  the hypothesis of Gerlach  and Boll
these most minute fibrils connect with the finest ramifications of the
ganglionic  processes.  There would then be a secondary connec-
tion  merely between  the processes of the latter and the largest
aggregate of axis-cylinder fibrils.  Ganglionic  cells and axis-cylin-
ders in their connections would be parts of two, not of one proto-
plasmic body.  This independence  of  the ganglionic cell  as  an
anatomical centre does not admit of a doubt  as to its importance
as a  functional  centre.
   The composition of the axis-cylinder from the fibrillary elements
of Schulze would not prove the isolation of these fibrils, for the
axis-cylinder is not properly isolated until surrounded by a medul-
lary  sheath.  Originally  gray substance similar to the granulated
basis substance of  the  cortex separates the axis-cylinders in
the medullary layer  from one another  (Jastrowitz, Boll, Flechsig).
From this  Jastrowitz draws the correct inference that in default
of a connection between this basis substance  and the fibrillary
elements (cf above) we must look upon the granular  substance as
the true isolating mass between the fibrils.  Isolation is therefore
carried  further in the cortical than in the medullary substance,
and  yet the isolating mass retains its embryonic character, for the
granulated basis substance does not become medullated.
   The anatomical structure of a functional  centre demands that
there should be no isolation in the  centre itself.  The striation of
the ganglionic processes  does  no more prove the isolation of its 
The Cortex.                       65
fibrils than it did in the case of the axis-cylinder.  And then again
the connection of the striated ganglionic processes with the proto-
plasm of the cortical pyramids effects the realization of the transi-
tion from the " fibrillar " to the " granular " where isolation ceases.
Beyond this point the doctrine of cortical centres does not venture
This is certainly not a novel  point of view, but fortunately one
that suffices for physiological purposes.  We  have no reason  to
grow sceptical on this point until  we shall  have  succeeded in
isolating  Schulze's finest ganglionic fibrils from the surround-
ing protoplasm, as has been done  in the granulated basis sub-
stance.
    The development of the axis-cylinder from the cortical nerve-
elements, and the relation * of the former to the pyramids are as
follows :
    The  pyramids  send median  base processes (Meynert),  which
need not ramify (Koschewnikow), directly from their base into the
medullary substance.  Moreover, the pointed apex process extend-
ing from the third layer to the most external layers of cortical ele-
ments divides into a  multitude  of terminal ramifications,  the
finest  spurs of.which return loop-shaped  toward the white sub-
stance  (Boll)  (?).   These delicate  filaments collect and form
stouter filaments ;  these in turn  give rise to  the myeline,  which
is, therefore, in the first instance, a product of the pointed  proces-
ses.  Now  this myeline is deposited next to those  axis-cylinders
which are formed by the median-base processes (Gerlach).  The
lateral processes could, in the same way, participate in the  origin
of  the  white substance.   The   gray  substance,  however,  is
traversed simply by nerve fibrils which enter into no combination
with it.
    In regard to the grouping of ganglion cells, it is very evident
that the dimensions of the pyramidal cells are directly proportion-
ate'to the distance they are separated from the  external cortical
layers; that they  are  small  externally,  and  steadily increase in
size as far  as the granular layer.   The apex process  splits  up
not only into a number of  terminal ramifications,  but gives  off
lateral  branches  nearer to the protoplasm,  which (fibrils) take
part in the  formation of the so-called fibrillary network.
    Even Gerlach's preparations, which I have been  permitted to
examine, do not enable one to detect any other internodia but the
ganglionic cells, so that the minute fibrils seem to form a compact
'According to Gerlach's staining method :  potass, and gold chloride I; 10,000 water. 
66
Psychiatry.
mass rather than a net.  The greater the  cortical distance along
which the  apex  process contributes branches to this network of
fibres, the  more  fibrils this process will contain, and  the stronger
this process will  necessarily be.   Inasmuch as  these ramified
branches are continued in  some way or other into the protoplasm
of the pyramid, it naturally follows that stronger processes, or an
increasing number of branches, will  engender larger pyramids.  I
need scarcely add that the smaller pyramidal or other nerve cells,
at a distance  from the cortical surface ramify in the region  im-
mediately surrounding them—i. e., at a greater distance from the
cortical  surface.   Stout and short,  or long and  thin,  pointed
processes do  not  occur.   The external layer of pyramids, whose
pointed  processes  soon enter  the  fibrillary net, is composed
naturally enough of smaller elements.  These  pyramids  are  not
wide apart either, for  their lateral  processes have but a narrow
area  over which to distribute  their ramifications.   This refutes
the  opinions  of those who hold that the small pyramids are sen-
sory, and the large pyramids motor in function ; it also disproves
the theory  of Wundt, that the large  pyramids are the old, and the
small pyramids the young  cells.
   The  pyramidal and spindle-shaped  cells contain  either oval,
pyramidal,  or spindle-shaped nuclei.   The  latter forms are found
to be quite as  numerous in brains that have never been hardened;
for this reason Boll's view, that they are artificial products, seems
untenable.   These peculiar configurations of  the  nucleus seem
to me to support the opinion of Beale, that the cell nucleus is sur-
rounded  by  an  optically  denser protoplasm, which is  differen-
tiated from the  external  layers  of  protoplasm.  The  greater
density of the nuclear portion of the protoplasm screens the oval
nucleus, but it is penetrated by the glittering of the nucleolus.
Owing to this  dense protoplasmic layer the outlines of angular or
pointed nerve corpuscles, together with their prolongations, seem
crowded into  the processes.
   No morbid change and no physiological experiment give us any reason to hope
that we shall be able to explain the difference in form of cortical elements in closely
neighboring layers.  Morphological interpretation is the only method  which can come
to our rescue.  The nerve corpuscles of the gray anterior horns of the spinal cord,
of the central nuclei of the hypoglossal, facial, and abducens nerves, and as far up-
wards as the oculomotomerve, all show long, slender cell-forms with numerous processes.
These processes seem to arise with a broad base from the body of the cell.   The same
peculiarities of configuration which we observe in those nerve cells  which are con-
nected with centrifugal nerve tracts, are found in the cortical pyramids, and there can
be explained only by the similarity in the distribution of these bodies.  Gerlach  has 
The Cortex.
67
compared the median base process with those spinal cell processes which  enter the
anterior roots.   The granules of the fourth cortical layer, which are distinguished from
the free nuclei by their size and protoplasm, from spider- and spindle-shaped cells by the
distinct boundary of the protoplasm, and by a lesser number of stout processes, may
be likened to those branched  ganglionic cells which occur in centres connected with
centripetally conducting tracts, as in the substantia gelatinosa of the fifth nerve and in
the posterior horns of the spinal cord ; these granules maybe likened, also, to the inter-
nal granular layer of the retina, and to the smaller elements of the granular layers of
the olfactory lobe.

    The axis-cylinders of  the fibres of the convolutions  and of the
entire fore-brain are  developed  at a very early embryonic stage.
In  the  chick  they  develop from  spindle-shaped  cells  on the
fourth to  sixth day after  impregnation (Boll).  Simultaneously
with  these elongated formative  cells, chains  of  round elements
appear which  change  into  spider-cells,  granules,  and ganglion
cells, which Boll supposes (perhaps  correctly) to be diffused over
the entire  medullary substance of the  hemispheres.   Jastrowitz
thought them erratic.  These chains of connective-tissue elements,
separating  as growth continues, lie between  bundles  of  fifty to
sixty fibrils.  The axis-cylinders  are separated by a gray, granu-
lar, albuminous  basis  substance, like  that of the cortex.  The
fibres in the fore-brain do  not develop medullary sheaths  until
later on, and for that reason are separated by gray substance only
until long afterbirth  (Jastrowitz),and in some parts up  to  the age
of nine months (Flechsig).   This gray substance may even appear
darker than the  cortex (Jastrowitz), though  later on it becomes
differentiated as  the white substance.   The transition   of fun-
damental gray substance into medullary sheaths  is preceded  by
a  fatty  infiltration  of  the  latter, and  by  the  appearance  of
granular  cells  possessed  of amoeboid  movements  (Boll);  but
later  on their  fat-granules  disappear, and these  cells are  lodged
between the medullary fibres as connective-tissue cells.   Granular
cells  are present  generally in  the  medullary substance  from
the  fifth   month of  intra-uterine  life  to   the fifth   month
post partum.  A remnant of intrafibrillary gray substance is per-
petuated.    The   star-shaped  connective-tissue cells  (Meynert),
called also spider-cells (Jastrowitz) and  fusiform-cells (Boll), form,
after  the complete  development  of  white medullary  substance,
an  interstitial  fibrillary  network of  nerve  fibres  and  bundles
of the fore-brain,  varying from fibres of minutest dimensions to
fibres of respectable  size.    These cells seem  to be fixed every-
where to the medullary substance, while the free nuclei,  present 
68                      Psychiatry.

in varying  numbers, might be classed  as  remnants of the  gray
medullary substance.
   The cortex of the outermost part of the occipital extremity, and
of the calcarine fissure (to which the vertical line gives a H shape,
and the occipital extremity a distinct wall), can be divided macro-
scopically into  three  well-defined layers:  (i) an  external  gray
layer ;  (2) a median, distinctly-limited white layer; and (3) an in-
ner gray layer.   Microscopically we can discern eight layers.  The
eight-layer cortex is distinguished from the four-layer cortex :  I.
By the reduction of the layer of pyramids  to a narrow concentric
layer (Fig. 25,  2), within which the size of the pyramids varies
less than  in the  five-layer type.    According to  explanations
given above, this  is  due  to the lesser distance  of  the inner-
most pyramidal strata  from the neuroglia layer.  2. By three
granular layers, which  constitute  the  third, fifth, and  seventh
layers.   The granules are curiously  intermingled with small py-
ramidal and small  spindle-shaped cells.  Owing to the  narrow-
ness of the  medullary substance and  the  consequent  greater
parallelism of the stratum propriwn of this portion of the cortex,
its eighth  layer, answering to the fifth layer of the first type,
gives us valuable information regarding the  spindle-cells, which
are larger  than th6se spindle-cells to  be  found interspersed  in
other layers.   3. By the less densely packed  elements  of the
third, fourth, and sixth layers, comprising chiefly small pyramids
and transverse spindle-cells.   Both  these layers are fitly called
intergranular layers.   These  intergranular  layers contain  at
considerable distances apart either single pyramids of astounding
size, or groups  of two and  three such  pyramids.  These are the
largest ganglion cells to be met with  in  any part of the  cere-
brum.  The pyramidal cells appear upon the inside of the granu-
lar layer;  their long pointed processes traverse the more  external
layers, and pass through the pyramids of the  second intergranu-
lar layer—through two granular strata—through an intergranular
layer and a portion of the pyramidal layer. The gigantic dimen-
sions of these solitary pyramids can be explained on the principles
before  alluded  to in regard to the progressive increase in the size
of these pyramids.  The  presence  of large numbers of small
pyramids, especially in  the second and third granular layers, as
well as in the layer of spindle-cells, would  lead us to believe that
these  pointed processes and their ramifications terminate in that
part of the gray  network of fibres  which does not belong  to 
The Sulcus Calcarinus.
69
the most external layers of the
cortex.  The three granular and
the  intergranular  layers  con-
sist really of mixed elementary
forms, among which the gran-
ular ganglionic  cells  prepond-
erate.  The connection  of the
pyramids with  the previously
developed delicate radial  med-
ullary bundles of  the  cortex is
easily recognized.   The small
fusiform (spindle) cells of these
layers are contiguous  beyond a
doubt with transverse  nerve
fibres, which are  by no means
numerous enough, however, to
constitute,  as  Kolliker would
have it, the white substance of
the  intermediate strand in the
cortex of the sulcus calcarinus.
    To explain satisfactorily this
white, intermediate strand, we
must, because of its well-defined
boundary, have  recourse to the
lack  of pigment in the barren
intergranular layers,   for  the
nerve corpuscles evidently carry
the  pigment which is  respon-
sible for  the deep tint of the
gray substance.  Besides, the
effect of lack  of pigment  is
intensified by radiating medul-
lary bundles which are  not prom-
inent  in  other  internal  layers
—in the seventh and eighth for
instance,—where the impression
gained from numerous pigment
cells overshadows all else.
 
7o
Psychiatry.
    Similar circumstances conspire to bring about a diffuse, paler tint of the middle
portion of a section  of the cortex taken from the central convolutions.  Betz has
stated that  the anterior central convolution  contained groups of particularly large
pyramids, which he thought were the circumscript motor centres which Hitzig, on the
strength ©f his physiological experiments, relegated exclusively to the anterior central
convolution of the brain in dogs and monkeys.  Apart from the mistake Ilitzig made,
and which we corrected above, in establishing  the homologon in carnivora of Ihe an-
terior central convolution, it has been proved that the size of the pyramids depends
upon their distance from the cortical surface.  The largest pyramids will, therefore, be
found in the broadest cortical region ; but the  broadest cortex is that of both central
convolutions.  The third layer,  the equivalent of the third layer in Fig. 24, is very
broad, and contains larger pyramids, which are naturally farther apart than their  fel-
lows in the dense groups of small pyramids.  For this reason we observe an increasing
lack of pigment near the surface of the  cortex, due to a gradual diminution in  the
size of the  pyramids.  And on the other hand, these pyramids  do not move asunder
by reason of their size alone, but their regular distribution is interfered with by the
steady increase  inward in the circumferences of radiating bundles of fibres, which at
the same time intensify the paler tint of the third layer.  The largest pyramids appear,
therefore, to be  arranged in small groups at some distance from one another. It would
be wrong to argue from this that these large pyramids have a different signification
from the smaller ones.  Luys is in a great measure responsible for this mistake.  Betz
appears to me not  to have made a discovery, but to have failed to appreciate the gen-
eral relations which obtain in the primary disposition of the cortical elements.

    The gyrus uncinatus and the cornu ammonis, which represents
a continuous involution of the former's cortex, are  peculiarly con-
structed, and  show  but  a meagre variety of cortical nerve-forms.
The  cornu  ammonis  contains principally cortical elements of the
pyramid  type.   Essentially the  same is true of the lobi  olfactorii,
joined to the  gyrus fornicatus by  frontal  and  temporal connec-
tions  (olfactory convolutions).   The cap  of  the  olfactory  lobe,
the bulbus olfactorius (Fig. 10, Olf.)  exhibits a special kind of cor-
tical  stratification.  Nearest to the surface lies the origin of the
olfactory  nerve, which passes through the lamina  cribrosa to the
Schneiderian  membrane.    These  nerves  take  their  origin  in
glomeruli which  contain  capillary loops  (Schlingen) and small
nerve cells (Meynert).
    The glomeruli olfactorii are transformed in  mammals (Clarke),
and in the  lower vertebrates (Leydig), with the aid of gray sub-
stance, into round masses (stratum glomerulosum), between which
granular  nerve cells are  collected and  heaped up.   1.  This dis-
tention of  the glomeruli in  animals is a  single instance of the
proliferation, independent of the number of nerve fibres and cells,
of amorphous connective-tissue substance in animals, in  contra-
distinction to  its reduction  in the  gray substance of man (page
56).   2.  Toward the inner side  of the stratum glomerulosum the 
The Claustrum and Amygdala.              71
olfactory lobe contains the gelatinous (connective-tissue) layer of
Clarke, which, like the cerebral  cortex, possesses on the outside
small nerve cells, which are changed into larger, angular, elongated
nerve  cells as we  proceed inward.   3. Closely packed  granular
layers  succeed  the innermost largest nerve cells as they do in
the cerebral cortex; these granules are  divided into strata by the
medullated substance  parallel to the surface of the olfactory lobe.
   Animals whose  olfactory lobe is hollowed out by a diverticulum from the lateral
ventricle exhibit an ependymal layer with columnar, ciliated endothelium.
   4.  Through complications a fourth type  of cortical substance
is created, represented in  the cortex surrounding the fossa Sylvii,
where a  gray lamina, the claustrum, runs  parallel  to the cortex
of the island of Reil (Fig. 6, CI.), of the operculum (Fig. 5, between
J  and  L),  of the  first temporal  lobe,  and,  continuing  beyond
the anterior fissure, parallel  to the  cortex of the orbital surface
(Fig. 26,  CL.).   The claustrum is developed out of the formation
     Sagittal Section through the Brain of Hamadryas, near the Island of Reil.
    Fr. Tm. Occ. Frontal, temporal ends and occipital region of the fore-brain.  I.
Island (should have been placed over the entrance to the Sylvian fossa), op. Opercu-
lum,  j. Upper margin of the island.  CL. Claustrum. A. Amygdala. Cd. Anterior
commissure.  Am. Cornu ammonis.  Ci. Inferior horn of the lateral ventricle.  Cp.
Posterior horn of the lateral ventricle. NL. Lenticular nucleus.  NC. Temporal end
of the caudate nucleus,  nc. Hindermost portion of this nucleus. Between the two the
stria cornea.  Ce. Medullary capsule of the external geniculate body.

of  spindle-shaped cells  of  the fifth cortical layer;  the  elements
of  this layer  and of the  claustrum  resemble  each  other,  not
only in  size  and  shape,  but  also   in being  parallel  to the
surface  of the cortex.   The claustrum, which lines the inner
surface of the  island, adapts itself to  the fan-shaped  form of the
latter, the handle of the  fan pointing downward  (basis insulae). 
72                       Psychiatry.
The margin  of  this trilateral  fan  is bent outward on  all three
sides.  The claustrum is continued forward beyond the  anterior
fissure into the  posterior margin  of  the orbital surface  of  the
frontal lobe, upward  into  the operculum, and below,  but to a
lesser extent, into the first temporal convolution.   This  fan-
shaped formation is furrowed  or  rather folded to correspond to
the rise and fall  of the island-convolutions.  The pedicle (handle)
of this fan-shaped formation, a ball-shaped body—the amygdala,
—represents at the same  time the most anterior portion of the
uncus lying to the inner side of, and behind, the base of the island.
The amygdala (Figs. 6, 26, 30, 32,  A.) is composed of the same
elements as the  claustrum.  Between  these two bodies (claustrum
and amygdala) there are small transitional heaps or strips of gray
substance,  which cannot be definitely classed as belonging  either
to the claustrum or to the amygdala, but together with these two
formations  constitute  a  continuous  system  of gray substance
(Fig. 26,  CL., A.).
   Amygdala and claustrum are separated from each other by the
anterior commissure in those frontal (transverse vertical) sections
of the brain, on  which the lateral portion of the anterior commis-
sure, descending to the temporal  lobe, is seen to pass between
them (Fig. 6, Ca., CL, A.).   The claustrum is a formation of gray
substance.   The nerve cells of  this formation are present also in
the white substance of the island, as well  as in the external capsule
between  nucleus lenticularis and  claustrum,  and  in all  these
structures these  cells have their axes turned in the same direction.
I wish to call attention again to the connection  existing between
the claustral investment of the Sylvian fissure, and the association-
bundles of that region.  (Compare  Fig. 19 with Fig. 26.)
   The claustrum is not  to be ranked among the ganglia, as it
communicates with the fibrae propriae of the  cortex.  The  cere-
bral ganglia are connected  with the cortical projection-bundles
only.
   Before  passing to the study of sections of the cerebral ganglia
and the projection-system I must stop to refer again to the med-
ullary formation of the  anterior commissure.   Like  the corpus
callosum this commissure represents a system of fibrae proprise con-
necting both hemispheres,and uniting with those commissural fibres
which join both olfactory lobes, themselves parts of the hemispheres.
According to the very general account given  of it in Fig. 20, the
anterior commissure consists apparently  of a round (on section, 
Commissura Anterior.
73
oblong)  bundle of  fibres, spreading  out principally in  the tem-
poral  and  occipital lobes.   But a more thorough  examination
of the anterior commissure (on sections) shows that a not incon-
siderable number of its bundles originate in the olfactory  lobe,
and pass upward from the posterior margin of the trigonum olfac-
                              Fig. 27.
   Transparent Frontal Section through the Cerebral Ganglia of Man.  Anterior
                            Commissure.
   J  Island of Reil and its medullary substance. CI. Claustrum.  Ce.  External
capsule.  L.1, L.2  First and second divisions of the lenticular nucleus.  Nc, Nc.
Ventricular and basilar portions of the caudate nucleus.  Ca.  Anterior commissure.
Olf. Olfactory bundles passing  to anterior commissure.  Orb. Orbital surface.
torium through the substance of the  lamina perforata anterior.
And yet these bundles are not sufficient to account for the size of
the anterior commissure (Fig. 27, Ca., Olf.). We must, therefore, in-
fer that the anterior commissure contains bundles also which con-
nect the occipital and temporal lobes, but stand in no sort of relation
to the olfactory lobe.   In man and animals this contribution to the 
74                         Psychiatry.

anterior commissure from the olfactory lobe comprises most of the
medullary substance of these lobes.   The relative position of the
bundles entering the  commissura anterior from the hemispheres
and from the' olfactory lobes  is such, that the  bundles coming
from the latter  join the commissure  below, and those from the
hemispheres form  an  acute  angle in  the frontal plane with the
                               Fig. 28.

  Frontal Transverse Section through the Brain of a Dog.  Anterior Commissure.

    R. Cerebral cortex.   F. Gyrus fornicatus.   M. Medullary substance of the
fore-brain.   Sp. Septum  lucidum.   Ye. Cerebral ventricle.   Nc.  Nucleus cau-
datus.  L.1 Cortex of the  island of Reil.  Mi. Medullary substance of the island of
Reil.  Ce. External capsule.  L. Lenticular  nucleus.  CI. Claustrum.  Ca. Fibres
from the hemispheres to the anterior commissure.  Olf. Olfactory division of the
anterior commissure.

upper portion of  the commissure.    Examined from this point  of

view, we observe that in the brain of a  dog the superior—the

hemispherical—portion  of  the  anterior  commissure  (Fig. 28)

    'The outer lower L on the figure should be J.  (Engraver's mistake.)—S. 
Ganglia of the Brain.
75
is smaller  than  the inferior portion  coming  from  the  olfac-
tory lobe.  Consequently, the hemispherical bundles  of  the an-
terior  commissure,  in  animals   having  large  olfactory  lobes,
would  by  no  means  cover in  amount   the  wealth  of  com-
missural  fibres.    For  that  reason  the bundles  of the  anterior
commissure must serve to unite both  olfactory lobes.  Further-
more,  it is apparent  to  the  naked eye  that fasciculi  of the
anterior commissure cross  each other after the fashion of a twisted
rope, and that these bundles are asymmetrically distributed in
both halves of the anterior commissure.  The latter undoubtedly
possesses decussating bundles which connect  each olfactory lobe
with the temporal and  occipital lobe of the opposite side.   It  is
equally  certain, however, and this we learn from longitudinal
sections, that  the entire medullary substance of the olfactory lobe
does not pass into  the anterior commissure, but that a part of
this medullary substance forms into  bundles which lie beneath the
commissure and enter the basilar portion of the nucleus caudatus,
i. e., the mass between  the  lamina perforata  anterior  and the
commissura anterior.   The  course  of  these olfactory  bundles
within and  outside of the anterior commissure establishes  a forma-
tion similar to the optic chiasma as interpreted by Joh. Miiller.
    As early as 1S61 Clarke described the cerebral cortex, and more perticularly the
eight-layer type of the occipital lobe.  Clarke differed from us in enumerating but six
layers;  for he does not separate the pyramidal, granular, and spindle-shaped cells at
their proper boundaries.  Clarke found that the cortical structure varied very much as
regards the width of the several layers, and described varieties of type which may
be found in one  and the same convolution.   Careful study of the structure of all
convolutions will not permit me to establish any other types but those I have described
above.
       GANGLIA OF THE  FORE- AND  INTER-BRAIN.
    The ganglionic masses of the brain, which are traversed by a
large  proportion  of  the  projection-system, must be regarded as
brain-forms (Organbilder), the contours of which are determined in
the brain by the course of the projection-fibres.  This is exhibited
very clearly on gold-preparations in which the gray matter is not
stained.
     THE GANGLIA .OF  THE FORE-BRAIN (PROSENCEPHALON).
the caudate and lenticular  nuclei, really form but one mass, the
continuity of  which is interrupted  here and there  by the projec-
tion-system.   The projection-fibres surround the lenticular nucleus
in the form of the internal and external capsule. 
76
Psychiatry.
   In  regard to the confluence of these masses we must note:
   I. That in the frontal lobe the large ganglionic masses of the
fore-brain are divided into layers by the medullary lamellae  from
the internal  capsule ;  the more anteriorly they are situated, the
broader will  be the bridges of gray substance  in  this fore-brain
ganglion between  the  successive layers  of white fibres.  Thus
Gratiolet distinguishes  between the corpus striatum intraventricu-
lare  (nucl. caudatus) and corpus striatum  extraventriculare (nucl.
lenticularis).   Forward of the inter-brain {diencephalon) the inter-
nal capsule  lies  solely between  these  two ganglia (Fig. 5, Cpi.;
Fig.  27, Ci.).
   The sections of the projection-bundles belonging to these mas-
ses contain not only fibres passing to the fore-brain ganglion, but
also  radiating fibres which travel from the frontal  cortex to the
anterior pedicle of the thalamus.  (Compare Fig. 5  Cpi. with Fig.
21 f. Th.).  In the diencephalon the corona radiata sends forth,
in addition to the inner and external capsule, an oblique group
of bundles lying  one  behind the other and collectively passing
under  the caudate nucleus to the stratum zonale of the optic
thalamus.  In the  region of the inter-brain the caudate nucleus
lies no longer to the inside of the internal  capsule  and next the
lenticular nucleus, but on the former and above the latter (Figs.
6, 29—Nc., Th„ Ci.).
   2. On longitudinal  sections  [Fig. 30, Pi. (n. c.)] the internal
capsule exhibits  a number of spindle-shaped masses of gray sub-
stance, which connect the caudate nucleus with the more exteri-
orly located portions of the lenticular  nucleus.
   3. On the upper wall of the inferior horn in the temporal lobe
there is  a complete fusion of  the  temporal extensions of  both
these ganglia (Fig. 26).   In the  direction of the occipital lobe the
caudate and lenticular nuclei are separated by medullated bundles
which pass from  the white substance of the hemispheres to the
capsule of the external geniculate body (Fig 26, NL., NC, Ce.).
   The nucleus caudatus constitutes, in reality, the internal margin
of the lenticular nucleus, or, better still, of its lateral gray division.
The  lenticular nucleus  is a wedge-shaped body ;  its lateral di-
vision, but imperfectly separated from the nucleus caudatus by
medullary substance, forms the base of this wedge,  looking for-
ward and outward (Figs. 5, 6, 19, 23, 26, 30, 32, 34, 36—NL).  The
nucleus caudatus bears a certain definite quantitative  relation to
the lenticular nucleus :  anteriorly, where the surface of the lentic- 
Nucleus  Caudatus.
77
ular  wedge is broadest,  the  nucleus caudatus  develops its club-
shaped head, while it diminishes  posteriorly, and finally dwindles
down into the cauda, just  as the lateral  division of the nucleus
lenticularis is continued by means of a narrow, defective (notched)
band to its equally meagre temporal continuation.
   As the arch-shaped  portion  of  the fore-brain ganglion, the
caudate nucleus surrounds with its head the lenticular nucleus as
far as the basilar surface, and does by no means originate in the
cerebral  ventricle.   By curving  spirally  about that part of the
internal capsule which contains the anterior pedicle of the optic
thalamus, the nucleus caudatus makes its way from the base of
lenticularis (Fig. 28, Nc. L.).
   We have said that as far as minute structure  and conn 
78                       Psychiatry.
 are concerned, these ganglionic masses must be regarded as one ;
 and yet quantitatively these two ganglia, caudate and  lenticular
 nuclei, are entirely independent  of  one another.  Man  possesses
 the  largest lenticular nucleus, but  his corpus  striatum  (caudate
 nucleus) is not proportionately larger than  that of mammals.   A
 similar difference is to be noted between the brains of the monkey
 and the dog.
    Frontal sections  exhibit the greater development of  the len-
 ticular nucleus in man and the monkey, whereas  the ganglion in the
 dog is inferior (quantitatively) to the caudate nucleus with its head
 extending around the internal capsule (compare  Figs. 6 and 27 with
 Fig. 28).  The arciform shape of the nucleus caudatus is the inevi-
 table result of the similar shape of the hemispherical arch around
 the fossa Sylvii.   This arch sends out as its corona radiata an arch-
 shaped group of projection fibres, which, as they enter the fore-
 brain ganglion, separate the upper portion—the  caudate nucleus—
 from the rest of the hemispheric ganglion (Fig.  21).   The lenticu-
 lar nucleus is clearly a wedge, the  longest  axis of which forms
 an acute angle, open anteriorly, with the longitudinal axis of the
 hemispheres.  The base  of this wedge-shaped  body lies to  the
 outside (and to the  front), its sharp edge  (Schneide) toward  the
 median surface;  for more  bundles  enter it from the  cerebrum
 than  leave  its  median portion  to  pass into  the crus cerebri.
 The fasciculi of  the  corona radiata  diminish in number  as they
 pass through  the  lenticular nucleus, on  their  way to the crus.
 The wedge occupies an  oblique position,  and for  that reason
 presents the same appearance on longitudinal  as on transverse
 sections.  The sharp edge is turned  chiefly  to  the  back, the
 base to the front.  This wedge-shape, which has been accounted
 for above, is complicated by the creation of three  or four concentric
 divisions.
   In the inner divisions, the medullary bundles passing through
 this ganglion are more closely packed ; first, because there is less
 gray substance, and secondly,  because not only their own bundles,
 but bundles also  from  the outer divisions, pass through these
 segments.  These internal  members  of  the lenticular  nucleus
seem, therefore, paler and  more medullated (globipallidi) than
 the external division in which the gray substance preponderates.
 The  vertical medullary partitions between  the division of this
 ganglion are termed  the lamince medullares nuclei  lenticularis.
The  greater development  anteriorly of  the gray substance  in 
Nucleus Lenticularis.
79
the nucleus lenticularis and its satellite, the nucleus caudatus, pro-
vides a greater number of ganglionic cells to effect the connection
with  the superior member of  the projection-system.   For  this
reason the  fibres of the corona radiata entering the posterior mem-
bers must be far less in number; and the paucity of fibres will be
more noticeable among those coming from the occipital than among
those from the temporal lobes.  The smooth anterior and exter-
nal surface of the  lenticular nucleus does  not receive any fibres
from the cortex, for but few bundles of  the external capsule touch
                      Fig. 30.

Sagittal Longitudinal Section through the Brain of Hamadryas.
    Fr. Tm.  Occ. As in previous sections.   CI. Claustrum.  A. Amygdala.  Am.
Cornu ammonis.  S. calc. Calcarine fissure.   D1F. Fossa Sylvii.  cp. Posterior horn
of the ventricle ; above it the caudate nucleus, behind it the greater  commissure,  ci.
Inferior horn.  ca.  Anterior commissure,  (n.c.) Caudate nucleus,  as islands of gray
substance in the corona radiata.  nl. Lenticular nucleus.  Pulv. Optic thalamus,  gi.
Internal geniculate  body.  ge. External  geniculate body.   II. Optic tract.   Pi.
PJ. Projection-bundles from the cortex.  Pd. Pes  pedunculi.   Tg. Region of teg-
mentum (index line passes behind and above it),  brs. Brachium of the  superior
bigeminal  body.  (In the wood-cut the semicircular bundles of the latter are not dis-
tinctly defined, nor is the index line properly placed.)

the  lenticular nucleus   superficially and cross  it  in a  direction

parallel to its outer surface. The finely ramifying radiatingbundles

of  the first division, which  collect into larger bundles, are dis-

tinguished from fibres of the corona radiata  by the  fact that the

latter are invariably  largest  nearest  to the  cortex, and do not

increase in the opposite  direction toward the crus  cerebri.   It can

be demonstrated from sections in any direction  that  the lenticular

nucleus  receives its cortical  fibres—the upper division of the pro-

jection-system—on its upper surface facing  the internal capsule.

The  cortical  radiations  of  the  capsula interna take  in  part  a 
8o
Psychiatry.
radial  (?)  course,  and  in part they pass through  the laminae
medullares, which are richly endowed with ganglionic cells.
   That the radial fibres are fibres of the corona radiata can be
stated positively only of the upper layers of the lenticular nucleus.
The nearer we get to the  basilar surface, the  more probable  it is
that these  radiating fibres issue from the ganglion  itself.   It is
quite easy to see that the radiating fibres of the globus pallidus
are connected with the  cortex through  the laminae medullares,
which pass vertically through the lenticular nucleus to  the base,
and  that the radiations originate  in the  ganglionic cells  of  the
cortex. The origin of the radial, branching bundles of the external
layer of the lenticular nucleus  is much more  mysterious.   I be-
lieve that these fibres also originate in the first (outermost) lamina
medullaris, and run in an  opposite  direction toward the external
capsule ; that, moreover, after they have joined the gray substance
of the lenticular nucleus near the  external capsule, they  turn
about and are thus continued, together with other radiating white
fibres of the globus pallidus, into the  crus (Figs. 30, 32, 34, 36).

   In regard to the nucletis caudatus we must take notice, apart from its connection
with the temporal lobe through the stria cornea, of the return of cortical fibres of the
internal capsule, after an interruption through the cells  of the ganglion, into bundles of
the crus.   There are no radial cortical fasciculi of the nucleus caudatus, but  we find
branching medullary fibres near the surface of the nucleus caudatus similar  to those
that pass through the internal capsule into the outer gray member of the nucleus
lenticularis.

   The  fibres of the second  section  of  the  projection-system,
which originate centrally in  the lenticular nucleus,  and  pass
peripherally  below the  fore-brain  into  the crus  cerebri,  and
indirectly into the anterior nerve-roots, and the equivalent cerebral
nerve-roots, have a double origin in  this ganglion.  These fibres
take (a) a vertical and (b)  a transverse course.
   (a) From the middle  divisions of the lenticular nucleus,  the
uppermost  layer, probably (?) the continuation of those radial fibres
of the external capsule which pass through the lenticular nucleus
without the intervention of the lamince medullares, enters the pes
pedunculi  in  front of those  fibres of the crus cerebri which de-
scend directly from the cortex (Fig. 33, 4). In the pes pedunculi,
however, said fibres do not  retain their anterior, superficial posi-
tion,  but  cross  those  cortical bundles  of  the pes  pedunculi
which take a vertical course  into the pons, in such a manner as to
extend from the base backward into the stratum intermedium of 
Nucleus Lenticularis.
81
the crus cerebri.   The  stratum intermedium of the crus includes
the substance of  Soemmering.   [Fig. 36  exhibits the continua-
tion of the bundles of  the  lenticular nucleus,  marked 4, Fig. 33.
These bundles are those extending to JS below the chiasma (II.)
and crossing the general run of fibres in the crus cerebri.]
    (b) The transverse bundles of the crus cerebri issuing from the
lenticular nucleus run, in part, parallel to  the  smooth basilar sur-
face  of  that  ganglion,  and constitute the ansa nuclei lenticularis
(Fig. 23, left side).  The departure
of  this  ansa  from the  medullated
ganglionic meshes of the lamina'
medullares is well shown  on  allci
frontal  sections  of  the  nucleus
lenticularis;  winding around the
base of  the  internal capsule, the
formation pushes its  way from the
inferior  surface  of  the lenticular
nucleus  upward, forming  on its
course  the innermost  bundles of
 the crus.  The  base of the internal
 capsule (its anterior  layers) passes
into  the  base—the  pes—of the
crus  cerebri.   The fact that the
bundles of the ansa  nuclei lenticu-
laris run upward, or more properly
speaking backward,  can be   best
and  easily demonstrated  by the  through  the red nucleus (NR)." fl.p
          J       .           .  T   Posterior longitudinal  bundles.   SS
Cleavage method (Abfaserung). In  stratum  intermedium  with  Soemmer
this  way we  Can discern laterally  ing's substance ans. 1. Ansa lenticularis.
       a_y                        j  jT Qptlc tract  g 0  b Basilar optic
the exit of the ansa lent, from the  ganglion. Z.  Stratum  zonale of optic
        u *.     f^Q1Qnt^„1nmn   thalamus (cut  across obliquely at lower
gray substance  of the lenticular nu-  z ^ st>. ^tilus imemus "Jin Jrnal pedi.
cleus;  in a median  direction the  cle) of optic  thalamus. Ca.  Anterior
 11          /•  .1           *„4-„  commissure.
development  of  the   ansa   into
the innermost fasciculi of the crus, which surround the bundles of
the pes, and  pass behind the pes into  the stratum  intermedium
(Figs. 6, 23, 31—ans. lent.,  SS.).    In addition to the superficial
stratum of transverse peduncular fibres of the lenticular nucleus,
we find  also a deeper system of  peduncular fibres which, coming
in successive  layers from the laminae medullares, interlace as trans-
verse laminae with  the vertical  laminae of the internal capsule
(Fig.  36,  above  II.).   The immediate  cortical laminae (Rinden-
        f 1- p.    g.o.b.
           Fig. 31-
 Sagittal Section through the Human
            Brain.
  Q.  Superior bigeminal body.   Cp.
Posterior commissure, f. rfx. Fasciculus
retroflexus. rfx.  The  same, passing
                          1. p.
                           SS. 
82
Psychiatry.
blatter) of the pes pedunculi  yield this area of interlacing fibres.
The necessity of having these  fibres interlaced is explained by the
fact  that  the lenticular  nucleus  lies (in longitudinal sections) in
front of, and the stratum intermedium of the cerebral  peduncle
behind, the  cortical bundles of the internal capsule (Fig. 36).
   The tractus opticus constitutes the ideal boundary between the
internal capsule and  the crus.  The pes pedunculi is made up of
vertical laminae, which  interlace at the nucleus lenticularis and
continue throughout its length (Fig. 34). The medullary substance
of the  lenticular nucleus  separates (probably not completely) from
the crus  cerebri above  its entrance into the pons, dividing into
laminae and  crossing the  crus posteriorly in the direction of Soem-
mering's substance.   In  the stratum intermedium the medullary
substance of the lenticular nucleus takes a downward course into
the posterior division  of  the  pons.   The  fasciculi  of the pedun-
cular stratum intermedium consequently increase on their down-
ward course. In the  upper half of the crus cerebri they are mere
scattered bundles; in the lower half, however, they form compact
transverse masses (Figs. 40 and 41).
   The stratum intermedium of  the crus cerebri with which  the
prosencephalic ganglion is connected, extends below the thalamus,
which  is separated from this stratum  by the lower half  of  the
discus  lent if or mis (Figs.  36 and 55).   A marked increase in  the
thickness  of the stratum intermedium does not take place until
the mid-brain is reached.  Consequently we may argue that  the
majority of  the crus fibres from  the lenticular nucleus enter the
stratum intermedium below  the  discus lentiformis (Fig. 55, ss.).
On this head consult  pp. 51 and 53.

                      CAPSULA INTERNA.
   Before giving  a description of the diencephalic ganglion we
must stop  to glance at the capsula interna  of  the lenticular
nucleus—-that complicated collection of fibres from the different
divisions of  the projection-system which separate the ganglion of
the  fore-brain from the  thalamus opticus—the  ganglion  of  the
inter-brain.   Cephalad the internal capsule connects with a large
portion of the corona radiata, caudad it is continuous with the crus
cerebri.  The extent  of  the internal capsule cephalad  is that of
the ganglia, caudad it is  bounded by the optic tract.  The minute
structure  of the internal capsule can be studied  best from  sec-
tions of a child's brain, which have been immersed in a solution of 
Capsula Interna.
83
palladium chloride 1  :1,000, before they are stained with potassium
and gold chloride I :  10,000. Such preparations should present com-
plete longitudinal sections of all the ganglia, and in  addition they
should be either sagittal or oblique toward the  fore and outer part.
The  internal  capsule  is a  conglomeration  of  medullated  fibres
from the hemisphere and the crura cerebri, and also of fibres from
the  cerebellum.   We  can discern  five different  orders of  fibres
in the internal capsule.
    1.  A portion of the internal capsule passes from  the cortex to
Sagittal Longitudinal Section through Brain of Hamadryas Passing through a Plane
                   between that of Fig. 26 and of Fig. 30.

    Fr. Tm. Occ. As in previous sections.   A. Amygdala, above it the claustrum.  ri.
Inferior horn of the ventricle.  Cp. Posterior horn of the ventricle.  NL. Lenticu-
lar nucleus ;  under its temporal prolongation, the  caudate nucleus ; below this,  the
optic tract.   (The line from II  is incorrectly drawn.)  Ge. External geniculate body.
Am. Cornu ammonis.  (The index line is too short.)  Pulv. Pulvinar.  brs. Ought to
point to the foremost semicircle of  bundles in the optic  thalamus (the brachium
corp. bigem. superius). S. cal. Should point to the calcarine fissure.  Pd. Bundles of the
crus from the internal capsule.  Pj. Projection bundles,  co. Anterior commissure.

the lenticular nucleus (Fig. 5, 6, 30, 32). These fasciculi course along

the superior  surface of this  nucleus, and on entering it, split up  its

superior margin.  They  do  not enter the external segment of this

nucleus in a  body, but insinuate themselves in part (?) as lamiiuc

medullares between the  various  divisions of the nucleus lenticu-

laris (Fig.  34, 1).
    2.  Another  set of   fasciculi   from  the  frontal  cortex  pass

through the  white  substance  of  the  hemisphere  and  finally 
84
Psychiatry.
enter the optic thalamus, constituting  a seriatim  defoliated mass
of  white substance along  the inferior surface of the  thalamus.
The medullated lines seen  on longitudinal sections are  the edges
of  the medullary  laminae  succeeding one another  from  above
downward, and alternating layer by  layer with  gray  substance.
This formation is the anterior pedicle of the thalamus, stilus ante-
rior thalami optici (Figs. 5,  29, 33, 36, 55).  From  this group some
fasciculi are contributed also to the stratum zonale.
    3.  Other fasciculi appear to connect the nucleus  caudatus with
the crus cerebri (Fig. 29).   These bundles intersect with those of
                              Fig- 33-
      Sagittal Longitudinal Section through the Brain of a New-Born Infant.
          (Preparation Stained with Potassium and Gold Chloride.)
    Th.  Optic  thalamus.   C.  gen. i. Internal  geniculate body.  n. 1.  Caudate
nucleus,  n. L.  Lenticular  nucleus.  A. Fasciculus Arnoldi.  P. P. Pes pedunculi.
2. Bundles from the stilus anterior of the thalamus.  4. Cortical fasciculi and direct
lenticular fasciculi.  5. Fasciculi from the internal capsule to the nucleus ruber.  L. ltf.
Should point to  the black lenticular plate in the angle between 4  and 5.

the stilus  anterior thai,  opt., lying to the outside  of  the  main
mass of the latter formation, and covering  the inner portion of
the lenticular nucleus.
    4. The pes pedunculi contains descending  medullated fibres
coming  from  two masses  of gray substance.  The anterior of
these laminated medullary  masses issues from the nucleus lenticu-
laris; the  posterior and  stronger  mass, from the medullary sub-
stance  of the  hemispheres—i. e.,  from the  cortex.  The latter
might fitly be termed the " anterior cortical  laminae " of the crus
(laminae corticales  antcriorcs pedunculi).  If we choose to speak of 
Capsula Interna.
85
a single bundle of fibres in this connection, it should receive  the
name fasciculus of Arnold (Fig. 33, 4).

    The posterior cortical lamina? of the crus, the bundles  of Tiirck, have been exhib-
ited in Fig. 22 (Tm.), and Fig. 5 (Om., P.).

    5.  The fifth  and  most  posterior  medullary division (of  the
internal capsule),  the  basilar portion of which  is  covered by the
laminae of the fasciculus of Arnold and  by the discus lentiformis,
does not merge into  the pes  pedunculi, but  passes  over this on
its  way to the red nucleus of the  tegmentum.   This bundle of
fibres, as seen  in longitudinal  sections (Figs.  33 and  36, 5), repre-
Transparent Vertical Cross-Section through the Human Brain, Including the Optic
                               Thalamus.

    Gk. Stratum zonale adjoining  the habenula conarii.  P. g. h.  Fasciculus retro-
flexus, or peduncle of the habenula. 2. Bundles from the corona radiata to the thalamus.
Between 2 and P.g.h., the semicircular boundary of the thalamic cone,  lamina viedul-
laris.  N.c.  Caudate nucleus.  Cr.  Corona radiata.  Ci. Internal capsule.  1. Radi-
ating bundles entering the lenticular nucleus (N.l.)  To the right of the lenticular
nucleus bundles from the corona radiata pass into the external capsule.  N.R. Red
nucleus with lateral radiating fibres from internal capsule.  C. lent.  Lenticular body.
S.S.  Median portion of the substantia nigra.  Pp. Pes pedunculi.  In it ascending
bundles are visible, which bend downward into the stratum intermedium.


sents the margin of a widely spread fan-shaped formation (Fig. 23).

On cross-sections these fan-shaped bundles are also distinctly con-

nected with the  nucleus  ruber (Fig. 34,  to  the outside of  NR.).

After  leaving the cortex these fasciculi  become entangled in the

complexities of the corona radiata.

    The discus lentiformis is connected with  a radiating arch of

cortical fasciculi, which  are in turn  interwoven with  the rest of

the  internal capsule.   These  fasciculi assert their individuality 
86
Psychiatry.
near their point of insertion, where they issue singly from this
confusion of bundles.  An innermost bundle of the internal cap-
sule (Forel) is part of this radiating formation.   Cordward, exter-
nal fasciculi leave the  discus lentiformis, and  pass through the
tegmentum into  the  brachium  corporis bigemini  inferius.   In
accordance  with previous statements of mine, the pes pedunculi
is  traversed on the inner three  quarters of its area  by bundles
destined only for the  substantia nigra of Soemmering (Fig. 34).
Its external quarter alone, into which the fasciculi of Tiirck are
continued, contains bundles of fibres which pass from the upper
surface of the discus lentiformis into the tractus opticus (fasciculi
nervi optici of Stilling).
   The discus lentiformis is an isolated ganglion which communi-
cates neither with the red nucleus of the tegmentum, nor with the
substantia nigra of Soemmering.
   All the  projection-bundles from the occipital lobe are part of
the corona radiata, and not of the internal capsule.   Among these
bundles there are (1) those which lie to the outer side on the crus
cerebri, and which I was the first to describe as bundles of Tiirck;
(2) those  which adjoin the former toward  the inside, and pass
through the brachium of the inferior bigeminal body into that
body itself ; (3) those which enter the  internal geniculate body ;
(4) those  which  enter  the  external geniculate body ;  (5) those
destined for the superior bigeminal body;  (6, and lastly) those
which  enter the pulvinar of the  thalamus (Fig. 5, Om. p., br. s.y
ge. i., ge. a., br. i., pulv.).

                      OPTIC  THALAMUS.
    The shape of  the  optic thalamus, and the medullary mark-
ings within it,  are  influenced (1) by the medullary substance of
the hemispheres ; (2)  by fasciculi of the optic tract  ; (3) by the
origin of the  tegmentum of the crus cerebri in the substance of
the optic  thalamus.
    Medullary layers make  a well-defined ganglion of the optic
thalamus.   Its most distinct connection is  with the tegmentum
by means of direct medullary fibres, which thus  make the optic
thalamus one of the ganglia from  which the spinal cord recruits
its fibres.   Its surface, facing the  lateral ventricle, is covered by
the stratum zonale, which extends from the stria cornea to the
inner margin  of the habenula—to the middle ventricle.   Beneath
the nucleus caudatus bundles  enter the stratum zonale (1) from 
Thalamus Opticus.
87
the frontal lobe as superficial layers of the anterior pedicle (Figs.
5, 21, 29, 54, 55) ; (2) from the parietal lobe (Figs. 6, 34);  (3) from
the temporal  and occipital lobes (Fig. 21); (4) from the retina,
passing to the inside of the posterior temporal  fasciculi  through
the tractus opticus; (5)  from the  ansa  peduncularis  along the
anterior and inner edge of  the stratum zonale (Figs. 21, 31) ;  (6)
from  the ascending pillar of  the fornix.
    These fasciculi of varied origin, covering the thalamus  super-
ficially before entering its depths, intersect at various points. They
contain ganglion cells (Boll) before they are merged with the sub-
stance of  the  ganglion proper.  The outlying temporal fasciculi
pass  over  the occipital and  parietal  fasciculi from behind, and
cover them as far as the outer margin of  the thalamus.   Further-
more, those bundles which come from the ansa peduncularis inter-
sect with bundles from the frontal lobes to the stratum zonale (Fig.
36).  Bundles of fibres from the ascending pillar of the fornix pass
obliquely from the  base of the brain through the interior of the
thalamus in order to reach the stratum zonale (Figs. 6, 31, 55).
    The surface of the thalamus descends vertically from the inner
margin of the stratum zonale to the third ventricle, and seems  to
consist of gray substance.
    But this gray substance is not part of the thalamus ; for it ex-
tends below the  optic thalamus into the infundibulum.  It is part
of that gray investment of the primitive medullary tube which be-
longs to the primary anterior vesicle, which later on develops into
the thalamencephalon ; the upper wall of the thalamencephalon
retains a  membranous  covering.   This  central gray substance,
which surrounds inferiorly the basal ganglion of the tractus opti-
cus (Fig. 31), touches externally upon the inner wall of the stratum
zonale of the thalamus.   The stilus internus, derived from the ansa
peduncularis, forms the median surface  proper of the thalamus,
and  the (median) most superficial fasciculi of the stilus internus
take an arciform course backward before entering the posterior
commissure.  The thalamic stilus anterior of the ansa peduncularis
takes its origin in the temporal lobe (Fig.  6), and in all probability
also  in the external capsule.
    The optic thalamus has an outer boundary of medullary sub-
 stance ; for the internal capsule of the lenticular nucleus may at the
 same time be considered the external capsule of the thalamus (Figs.
 5, 6) : and as soon as traces of the lenticular nucleus in the parietal
 region are lost, a continuation of medullary substance behind the 
88
Psychiatry.
internal capsule surrounds the thalamus on its outer side (Fig. 37).
The stilus anterior encircles the thalamus on its lower side (Fig. 35).
Like  the  stratum zonale, the  stilus anterior is a layer of  white
substance superimposed directly upon the thalamus ;  in entering
the thalamus it divides into laminae, and may therefore be con-
sidered an integral part of that ganglion.   In that  part  of the
thalamus which belongs to the parietal  region, a narrow layer of
substance  forms  what might,  roughly speaking, be  termed  a
claustrum.  (This is  the " lattice-like layer " of Arnold.)   This
formation  has  a  twofold  origin: (1) This outer narrow vertical
layer  of the ganglion (Figs. 30, 32) is bounded by fasciculi from
the temporal lobe which ascend with the gray substance of the
thalamus to the inner side of the transverse laminae of the parietal
region, and in  a  direction parallel to the external  surface of the
ganglion ;  (2) radiating fibres uniting the hemispheres with  the
corpus geniculatum externum, and, taking a vertical course, intersect
in the external gray  substance of  the  thalamus with transverse
medullary  laminae from the parietal region, which, on cross-section,
present the appearance of transverse fibres.
   Being  surrounded by a superior and inferior and by an exter-
nal and internal  medullary  wall, the  thalamus appears wedge-
shaped, both on  frontal and on sagittal sections.  On anterior
frontal sections (Fig.  6) the wedge  turns its back upward and its
edge  downward ; in sagittal planes, it is low anteriorly and high
posteriorly (Figs. 29,  36);  and on transverse  horizontal sections
(Fig.  5), it is  narrow  anteriorly and  broad  posteriorly.   The
longitudinal axis  of the thalamus is bent at its posterior end to the
outer side, a consequence of the median intrusion of the  mid-
brain (Figs. 16 and 17); from among the structures of the mid-brain,
the corpora quadrigemina press but little, while their appendages,
the corpora geniculata, pressing from the inner and  lower side,
crowd in upon  the optic thalamus (Figs. 5, 38, 30, 32).
   The formations surrounding the optic thalamus have shed con-
siderable light upon the superior division of its projection-system
between  cortex  and  ganglion.  We must now study: I.  The
course of the hemispheric fasciculi in the interior of the thalamus.
II. The origin of the tegmentum in the thalamus.  III. The basilar
structures  which   support  the  thalamus and which,  together
with the bundles of the tegmentum, present a special sectional
area.
   I.  The  hemispheric  (white) substance in  the interior  of the 
Thalamus  Opticus.
89
optic thalamus, the upper member of its projection-system, enters
it from the surrounding white  layer, and determines the arrange-
ment of the gray substance by dividing up into laminae, which can
be distinguished on gross macroscopical preparations. The medul-
lary systems referred to above furnish distinct boundaries for two
gray nuclei of the  thalamus.
   a. The crus adsccndens fornicis divides above, and, before it is
lost in gray substance, forms the boundary of the anterior nucleus,
tuberculum  anterius,   nucleus  caudatus thalami.    The  stratum
zonale, dividing as it were into an upper and lower lamina, partici-
pates in this boundary, through the mediation of a transverse layer
of fibres from the medullary substance of the  frontal lobe (Fig.
38, left a.).
   b. That portion of the stratum zonale which is derived from the
ansa peduncularis  bounds, and  passes through the ganglion of the
habenula conarii.  The small nerve-cells of this ganglion resemble
in form and density of arrangement those of the conarium.   Both
are united to bundles of the posterior commissure.
   c. Viewed on a cross-section  the  stilus internus (int. pedicle)
of the optic thalamus (derived from the ansa peduncularis) is seen to
spread, brush-like, at the outer side of the gray substance of the
III.  ventricle, over the  entire width  of the anterior half of the
thalamus to the inside and outside of the crus fornicis (Fig 6, st. i.
from Th. to Tp.).  In the anterior third of the optic thalamus, and
on frontal sections, we can discern  a group  of delicate bundles
coursing upwards from  the  internal capsule  over  the lenticular
nucleus into the deeper layers of the thalamus (Schnopfhagen).
In the thalamus these bundles run parallel to  those bundles of the
ansa peduncularis  which pass under the nucleus lenticularis.  The
former layer intersects from below with the radiating fibres arising
from the stilus anterior of the thalamus,
   d. The stilus anterior (anterior pedicle) of  the thalamus enters
this  ganglion, in which it is successively denuded  of the various
laminae of anterior medullary capsule (Figs. 5—Cp. i., 33, 36—2,38
—a,  5 5).   These laminae inflate themselves so as to present a surface
parallel to the convexity of the thalamus, and close like onion leaves
in upon the medullary capsule.   Layer by layer the medullary sub-
stance alternates with the gray substance, the spindle-shaped nerve-
cells of which invariably have their axes directed parallel to their
medullary laminae. The medullary substance  of the stilus anterior
crosses in the anterior  third of the thalamus the radiations belong- 
9o
Psychiatry.
 ing to the internal pedicle ;  further back it lies more to the outer
 side.   An inner (median) portion of the thalamus enters the pos-
 terior commissure ; the greater portion assumes a funnel shape, and
 passes directly into the tegmentum.  The laminae of the anterior
 pedicle have their  convexities  concentrically  arranged, conse-
 quently they, and the  intervening gray substance, appear trun-
 cated on longitudinal and sagittal sections, and present the appear-
 ance  of arches  convex anteriorly, and pushed one within  the
 other (Fig. 55), as seen in cross-sections.
   e. The radiating fibres from the parietal lobe  give rise in  the
 posterior  half of the optic  thalamus to transverse  laminae alter-
 nating layer by layer with gray substances (Fig. 34).
   f. The relations of  the  occipital  and temporal  lobes to  the
 thalamus  were demonstrated in a previous section  by means of
 preparations  obtained by the cleavage  method.  (Fig. 21, p. 47.)
 Its relations to the optic radiations were commented upon above,
 (see p. 86; also pp. 93,  94.)
   II. Other  medullary fibres in  the  thalamus opticus  indicate
 the origin of the  tegmentum of  the crus cerebri.    1. On cross-
 sections,  passing immediately in front of the  corpora quadri-
 gemina through the  widest part of the  wedge-shaped formation
 of the ganglion habenulae (Figs. 16 and  17), we see a considerable
 group of  fibres derived from various parts of  the stratum zonale,
 and  possibly also  from the posterior commissure.   These fibres
 pass through the swelling of the fifth-order-fasciculi of the internal
 capsule, through the nucleus ruber of  the tegmentun.   Longi-
 tudinal sections through this group clearly exhibit the passage of
 these  fibres  into  the  tegmentum.   As the  anterior  innermost
 bundle of tegmental  fibres, they either  curve around the outer
 side of the third nerve, or are inter-woven with the latter and are
 then continued into the fasciculus longitudinalis of the posterior
 division of the pons.   Through  the  intervention  of ganglion
 cells, these fibres are in all likelihood continued into the oblongata,
 ultimately into the  spinal cord.  To  this group of  fibres the
 name pedunculus ganglii habenulce, or fasciculus retroficxus, has
 been  given.  Forel suggested " fasciculus of Meynert."  (Figs.
 31, 34, and 35.)
   2. Above  the  nucleus  ruber  another nucleus  is  exhibited,
which  seems  to  unite toward the  median  line with the thal-
amus opticus, but is distinctly limited to the outer and  lower
side.   Appearances   would lead  one to suppose that arciform 
Origin of Tegmentum.
91
medullated fibres lying in the frontal plane had joined the cross-
sections of those fasciculi which surround the nucleus ruber (Fig.
34).   This medullated  arch is surrounded  on the outside by a
few  striated, irregular, concentric  medullary lines, striae med-
ullares  thalami optici.  But  these medullary fasciculi do  by  no
means  course within the frontal planes  alone.  Schnopfhagen
discovered on gold  preparations that these striae  consist of short
fragments of fibres and  of  cross-sections of fibres.   On lon-
gitudinal  sections of gold preparations  (Fig.  36) these striae are
seen to be made up of segments
of fibres from various directions,
some  of  which turn about to
enter the tegmentum of the crus.
On superficial examination  the
innermost  lamina   medullaris
forms a medullary vesicle, which
encloses  a semicircular area of
thalamic  gray substance isolated
from the remainder of the thal-
amus on  all but the inner side.
This enclosed  gray  substance
does attain  to  the  dignity of a
centre  in the  optic  thalamus,
for it is  not traversed  by the
same   longitudinal    fasciculi
which  contain  radiating  fibres
of the  anterior pedicle, and in-
vades much  larger areas of the
thalamic   substance  than  the
small semicircular area bounded
by the laminae  medullares after
their interruption by ganglion cells of the thalamus.
   These stria medullares  with ganglion-cells  interspersed  in
between  are simply slender  continuations of the anterior pedicle.
Cross-sections passed through the brain  trunk at  various levels
present the  same deceptive appearance of the innermost lamina
medullaris taking a transverse arciform course to the tegmentum.
This deception must be ascribed toe. number of concentric arches
diminishing  in size  in  a  downward  direction, of  which  one
would fit within the other.   At the level of the posterior commis-
sure, this arciform  formation has disappeared and  a cross-section
           P.cm.
            Fig. 35-
 Sagittal Longitudinal Section through
        the Brain of Lemur.
   C.Qu.  Corp.   quadrigemina.   Cp.
Posterior commissure passing into the
tegmentum.  P.gl.h. Fasciculus retro-
flexus of the tegmentum.  III. Oculo-
motorius nerve in  front of the pons and
behind the  corpus mamillare—Cm.  P.
cm.  I^S tegmental fasciculi.  Th. Optic
thalamus.   st. inf. Stilus  internus of
thalamus,  fd. Descending pillar of the
fornix  and  anterior commissure.   II.
Optic chiasm. 
92
Psychiatry.
of bundles has usurped its place on the outer side of the nucleus
ruber.   From this we may infer that longitudinal fibres contribute
to this origin of  the tegmentum by uniting downward  in  funnel-
shaped fashion.
   The laminae medullares of  the optic thalamus are, therefore,
composed not of  transverse fasciculi, but of  longitudinal bundles,
which are juxtaposed in such a way as to give rise to an arciform
formation on cross-sections.   The laminae medullares  seem to form
a dense medullary mass, and to be the  extension of long-drawn
fasciculi:  but this is a  deceptive appearance, due probably to the
                                          C.ext.

                                Fig, 36.

Sagittal Oblique section through an Infant Brain.  (Stained with Potassium and Gold
                               Chloride.)
    This section through the thalamus and lenticular nucleus of the right side runs
obliquely in an internal and posterior direction, and  would cross the median line if
continued below the corp. quadrigemina.
    Qu. Corp. quadrigemina   A.  Aqueductus Sylvii.  Th. Bundles of  tegmentum
from the  thalamus.   R.K. Lateral layers of the red nucleus.  Lm.  Laminse medul-
lares in optic  thalamus.  2. Interlacing of bundles destined  for the stratum zonale
and for the  thalamus in the internal capsule.  Nl.  Lenticular nucleus.  C.ext. Its
external capsule.  Plbl. Superior  peduncle of  the cerebellum above the point  of
decussation. P.P. Pes pedunculi.  J.S. Stratum intermedium.  L.ltf. Lentiform disc.
II.  Optic tract.   Ans.n.l.  Ansa  lenticularis, which  on its way to  the estratum
intermedium is  interwoven with the fasciculus of Arnold belonging to the internal
capsule,  y. Island.   The layers as far as the internal capsule are incorrectly repre-
sented in the wood-cut.
    N. B.—The apparent anterior end of the discus lentiformis represents the radiation
of the posterior longitudinal fasciculus.  The same is true of the dark crescent of the
optic tract.


introduction of transverse radiating fibres  from the parietal lobe.

These  radiating  fibres are  interwoven  with  the juxtaposed, teg-

mental fasciculi from the corona  radiata and pass in the direction

toward the third ventricle.  By filling up the gaps left by the  other 
Lamince Medullares.
93
order of fibres, these two distinct groups (the lam. med. and the
fasciculi from the parietal lobe) form a compact mass of medullary
substance.  Longitudinal oblique sections through the thalamus
exhibit, in addition, concentric arched formations, which are con-
vex  anteriorly  and open posteriorly, thus  contrasting  strongly
with  the appearance of  the  striae  medullares  on longitudinal
sections.  But the former do not form compact medullary masses ;
they  are the result  of the  defoliation  of the  stilus  anterior
in the optic thalamus, the resulting  laminae having a concentric
arrangement, and  presenting their  convex  surfaces toward the
Frontal Transverse Section through the Human Thalamus.
    Nc. Caudate nucleus.  Mh.  Medullary substance of the hemispheres.  Pd. Pes
pedunculi.  Z.  Stratum  Zonale of thalamus.  Cm.  Median commissure.  Fa. As-
cending pillar of fornix.  Fd. Descending pillar of fornix.  Lp. Cross-section and
radiation of the posterior longitudinal fasciculus.  Fc. Tuber cinereum.

third ventricle.  These laminae belong  to  an  anterior region of
the thalamus, in which they and the connecting fasciculi change
off with layers of gray substance, in  which they end and  originate
anew (Fig. 33).
   This entire system of nerve bundles, which enters the  thalamus
as its stilus  anterior,  and  emerges  from it as an outer division
of the  tegmental fasciculi, forms two stratified cones  with  ad-
joining   bases, situated about  midway between the ends  of  the
thalamus.  The  anterior cone is by far the  larger  one  of  the
two ;  the posterior  cone is hollow, and exhibits a  cleft-like  open-
ing toward the median line.  The innermost median area of  the 
94                        Psychiatry.
thalamus is occupied  by  the  system of  fibres composing the
internal  pedicle, which  connects with the posterior commissure
and  runs back  of  the fasciculus rctrofiexus.  This accounts  for
the formation of the median cleft of the tegmental cone in the
thalamus.
   At the same time the external concentric laminae which surround }he lamina medul-
lares, are too low to  rise in concentric fashion above the upper  segment of the latter.
There are several reasons for the lowness of these parts :  First,  the height of the brain-
trunk diminishes in the direction from the thalamus to the tegmentum; and, secondly,
we find that the fasciculi of the tegmentum, originating in an antero-posterior direction,
take, in keeping with the  parietal flexure a course from above downward toward the
pons.
   To the  tegmentum  of  the crus cerebri still other fibres  are
added, which  emanate from the posterior commissure, lie below the
fasciculus retroflexus, and  in passing to the front run parallel to
the " fasciculus of Meynert," 1 but later on curve  downward toward
the medulla (Fig. 35, Cp.).   The commissura media, between the
optic thalami, resembles the posterior commissure in structure ;  for
by the cleavage  method we can prove that bundles pass through this
commissure also, which unite the stilus interior  of  one side with
the optic thalamus of the opposite side (Fritsch, Hollander).  In
the thalamus these bundles seem to ascend a short distance in an
oblique longitudinal direction.
   A stout anterior  bundle of fibres from the tractus opticus con-
nects the retina with the thalamus.  This bundle ascends between
the corpus  geniculatum externum and the pes pedunculi, in front
of the pulvinar, and has its radiating fibres enter the thalamus on
its inner aspect.  These radiating fibres are situated at  some dis-
tance  from the fibres  connecting  the tractus  opticus   and  the
discus lentiformis,  and ought not, therefore, to be confounded
with the latter  group of fibres.
    III.  The  ganglia of the  fore- and inter-brain are surrounded
by medullary formations, which start from the  base of the brain
and take a course  about parallel to  that of the tractus opticus.
These constitute the substantia innominata of  Reil.  This med-
ullary layer  lies in front  of the  tractus opticus, and in  the
depths of   the  brain structure  it separates the optic tract from
the  pes pedunculi.  After  removing the optic tract (Fig. 23),
we  observe  that this  basal zone  undermines the lamina per-
forata anterior, and passes  through  the  nucleus caudatus as it
1 Forel suggested this designation. 
Girdle Formations.
95
did  through  the anterior commissure,  only in a more basilar
direction.
   There are morphological reasons for the formation of this girdle.
Its bundles pass from the outermost region of the brain-axis (princi-
pally from the corona radiata of the  temporal lobe, and from the
external capsule), over  the crus cerebri to the median points of
decussation (median and posterior commissures.   Schnopfhagen's
decussation). v  As regards the origin  of this medullary substance
of the ansa peduncularis (Gratiolet), from the temporal lobe, the
interweaving of  bundles of the ansa peduncularis with the  fibres
radiating into the pulvinar, and with the outermost bundles of the
pes pedunculi  (Fig. 23, Tm.), presents the appearance as though
the  outer fibres of  the  crus travelled in girdle-like fashion below
the posterior margin of the lamina perforata anterior to the inner
surface of the crus (Fig. 23,  in front of Pd.).   This is easily ex-
plained,  for the  radiating  fibres from the temporal lobe into the
brain-trunk either turn  backward to enter the  thalamus and crus
cerebri, or forward to enter the ansa peduncularis; but fibres run-
ning in both directions, from identical points of the sectional area
of  the temporal corona  radiata,  interweave  with one another.
This network of fibres,  and the course of these bundles in  oppo-
site  directions, can  be  well  exhibited  on cleavage  preparations
(Fritsch,  Hollander).
   The  following formations go to make up the basilar girdles of
the brain-trunk :
    1.  The tractus opticus, which not only sends decussating  fibres
through the chiasma into the optic nerve of the opposite side,
but also transmits non-decussated  posterior fibres into the  optic
nerve of the same  side.   Part of the tractus opticus  adjoins  the
tuber cinereum, and here its upper surface is connected with  Wag-
ner's ganglion opticum basale (Fig. 31, g.o.b.).  The chiasma is sus-
pended  as  it were  on  this ganglion, for  the latter  stands  out
entirely  free in a basilar direction.  The  ganglion transmits non-
decussated fibres to the optic nerve.
   2. In front of the chiasma we find the pedunculus scptipellucidi
(as the superficial layer of the Iqminaperforata anterior)  passing
beneath  the nucleus caudatus and to the outer side.

   Between this superficial layer of fibres and parallel deeper layers in the  caudate
nucleus, which, as was noticed above, arise from the ansa peduncularis, we discern a
special stratum of dense, transversely directed ganglion cells,  which are parallel to said
fibres, and can be traced as far as the external capsule.   They constitute a flat,  sharply 
96
Psychiatry.
defined, special ganglionic formation, which equals in area the lamina perforata anterior.
This ganglion ansalpeduncularis has its cells run parallel to the ansa peduncularis and
is intersected by bundles coming from the latter.
    3. Immediately  above  the  optic  tract  lies the  commissura
inferior (Fig. 6, II.), the median portion of which is lodged in the
convexity  of  the tuber cinereum,  while  its  recurrent lateral
portions lying to the outer side of, and immediately adjoining, the
crus cerebri, about  which  they form a belt,  run deeper in as-
cending.
    4. The ansa peduncularis.   We  can gain no insight  into the
general structure  of the brain-trunk  without keeping  in mind
preparations obtained by  the  cleavage  method.  From  such
preparations we  can  understand at a glance  the stratification
of the ansa peduncularis ; and transparent transverse sections will
corroborate in  excellent  manner the facts brought out by these
preparations.   The posterior surface of  the  ansa peduncularis
projects  gutter-like  over  the  commissura optica (Fig. 22 to the
right and next to the cut end of   the  optic tract).  The ansa
peduncularis is composed of three layers:  the internal pedicle of
the optic thalamus, the posterior medullary lamina  of the tegmen-
tum (so-called  fasciculus longitudinalis posterior),  and  the ansa
lenticularis; all three  layers taking  entirely different courses.
    a. The stilus internus forms the  most ventrad layer of  this
formation (ansa ped.).  It was fully described  on  pp. 88 and 89.
There is this,  however,  to be added, that  part of its  bundles
cross the median line through the  median commissure (Fritsch,
Hollander).
    b. The posterior longitudinal bundle (fasciculus longitudinalis
posterior) lies,  as viewed  from the base, above the stilus internus,
and under the  ansa lenticularis.  To the outer  side the three
layers of the ansa  ped. are super-imposed upon  and  cover  one
another.  In the median  direction  they are  distinctly separable,
for the  stilus  interior extends least, and the ansa lenticularis
extends  farthest, backward.   Within the ansa the posterior longi-
tudinal bundle is distinguished by a more  grayish tint.   This
applies to gross preparations,  from which we  may learn  also  that
this bundle  is softer than the other two layers.  On  their course
backward, parallel to  the third  ventricle, the stilus internus  and
the fasciculus longitudinalis posterior diverge to a  distance equal
to the height of the aquceductus, for the stilus internus passes be-
hind the aquaeduct  into the posterior commissure,  and the poste- 
           Radiations of Post. Long. Fasciculus.        97

rior longitudinal fasciculus enters the gray substance in front of
the aquaeduct.  These bundles, emanating from the ansa pedun-
cularis, are joined by others from the tuber cinereum, which lie
close to the inner surface of  the  third ventricle, or the infundibu-
lum, respectively, while, on the other hand, the commissura infe-
rior lies closer to the  outer surface  of the tuber cinereum.  The
bundles in question were demonstrated also by Schnopfhagen on
frontal sections of preparations which had  been stained with gold.
Turning back, at least a portion  of  these  bundles  enter Schnop-
fhagen's commissure, which lies  in the posterior wall of  the third
ventricle above the red nucleus and  behind the corp. mammillaria.
Below this commissure they course over the nucleus ruber (Fig.
31), and through the mid-brain (Figs. 40 and 41), probably as the
innermost bundles of  the cross-section.  This portion of the  pos-
terior long, fasciculus, derived from the  central gray substance,
seems solely to cover the ascending crus of the fornix ; in order to
enable  the latter to enter the thalamic  ganglion, the  posterior
longitudinal bundle divides into two laminae for a certain distance
of its course.
   The expression fasciculus longitudinalis posterior applies only
to the lower portion of this medullary formation, with which every
one has been  made familiar through Stilling's investigations, and
which has been described as lying in front of the aquaeductus Sylvii
in the mid-brain, and  in  front of the gray substance of the pons
(Figs. 40, 41,  42, 43—L.).  That portion  of this system, which  I
described more than twelve years ago as a connecting link between
the  ansa  peduncularis and the posterior longitudinal  fasciculus
(Figs. 31 from rfx to the basal fl.p.), is merely the inner  margin of
the powerful  radiation of the posterior fasciculus, which covers
the  entire posterior  surface  of the peduncular  system.   The
familiar leaf-shaped tapering (to the outside) form of the  fasciculus
longitudinalis posterior is nothing more than the lower, probably
imperfect, extension of this  medullary radiation.
   The  radiation of the posterior fasciculus represents a projec-
tion-system passing  from the medullary  substance  of the hemi-
spheres (from the cerebral cortex) into the central  gray substance,
which forms,  as it were, at one and the same time,  the floor of the
ganglia and the roof of the crus cerebri.
   All  the radiating  fibres  converge from the  central surface
toward the inner, thicker  margin of this radiating system, along
which they take a  sagittal course downward.  Fibres taking such 
98
Psychiatry.
a direction can be  seen  below the thalamus, on frontal sections
also  (Fig. 37, Lp;  cut made in the year 1866).   This fact was
recognized later on by Forel.
   The radiations  of the  posterior longitudinal fasciculus, from
the frontal lobe of the cerebrum, pass through the  internal cap-
sule  into the medullary substance above  and in front of the dis-
cus lentiformis, which is part of the radiation of the posterior fas-
ciculus (Fig.  33, the short,  interwoven bundles  of the fasciculus of
Arnold).
   The radiations from the temporal lobe bend  from below upward
with those of the external capsule in the ansa peduncularis, and
take the same course as the other fibres under the thalamus opticus
(Fig. 31).  In the ansa peduncularis these radiating  fibres do not
form a mere strand, but  a  broad,  stout  lamina,  the outermost
bundles of which lie so far distant from the median bundles that they
ascend to the outside far above  the tractus opticus (comp. Fig. 31,
fl.p. and Fig. 29, where the  ascent to the inner capsule is not marked
above II.).   That portion  arising above the  optic tract surrounds
the inner capsule with its concave surface turned outward, so that
the internal capsule is  seen  to  interrupt on sagittal sections the
course of the anterior segment  of radiating fibres into that seg-
ment which passes  over the crus.
   No  part of the  tegmentum of  the  crus extends as high
up in the  brain-trunk  as  does the  fasciculus posterior.   At
the  highest point the radiations lie in front  of the pes pedunculi
(Fig. 31 fl.p.), then in front of the stratum intermedium, the
bundles of which connect  at the outer side with the nucleus len-
ticularis ; after that this system of fibres rises above the  discus
lentiformis,1  and lower down the posterior fasciculus is pushed far
off from  the pes pedunculi by the nucleus ruber of the tegmen-
tum.  In order to cross the processus cerebelli ad cerebrum, the
fasciculus longitudinalis ascends from the median side of the prae-
peduncular (Wilder) radiations  to that process itself.  Over the
discus lentiformis, on the contrary, the radiating fibres of the pos-
terior bundles were covered by  the radiations  of the processus ad
cerebrum (Forel),  the latter lying close  under the thalamus as
the  fifth  layer of the internal capsule (Fig.  33, 5).   In this figure
the  discus lentiformis unites with the radiations of the fasciculus
longitudinalis posterior.   Figures 54 and 55 exhibit the radiations
of the longitudinal  bundles as dark cross-sections of medullary sub-

      1 In Fig. 31 it should fill out the space NR., fl.p. and of the bundles SS. 
Mesencephalon.
99
stance in front and above the discus lentiformis Lb. and L.lf. The
nerve-bundles passing over these belong to the radiation  of the
processus cerebelli ad cerebrum.
    (c) The ansa lenticularis has been described above, p. 81.


        C—THE  MID-BRAIN (MESENCEPHALON).

    Four symmetrically situated ganglia belong to each half of the
mid-brain region, viz.:  I. One half of  the upper, 2. one half of
the lower, corpus bigeminum ;  3. the external, and 4. the internal,
                               Fig. 38.
Horizontal Transverse Section through the Brain of a Dog—the Right Half nearer the
                           Base than the  Left.

    Fr  Frontal lobe.  P. Parietal lobe.  occ. Occipital lobe. Fr. Corpus callosum.
S  Septum pellucidum.  F. Descending pillar of the fornix,  a. Stilus anterior of the
thalamus  Nc. Caudate nucleus.  Th.  Optic thalamus on its median surface ; next to
the eray substance  of the third ventricle are bundles in the habenula  and to the out-
side of it which enter the decussation of the posterior commissure in  front of a  frag-
ment of the pineal gland, and are connected with the inner margin of the stratum
zonale ; the  median choroid plexus has been torn off from the latter,  ge. External
geniculate body.   II. Optic tract.   Bs., Bi. Superior and in enor bigeminal  body
Br  Brachium of the superior bigeminal pair.  c. Transverse bundles in the roof of
the aqueduct, adjoining  the posterior commissure.  Aq. Sylvian aqueduct.

corpus geniculatum.   In mammals we must speak of upper  and

lower corpora  geniculata  (Forel).   Both  parts of  the corpora

quadrigemina unite at the one end  with the hemispheres, and at

the other end  with the retina, which must be considered homolo-

gous to the bulbus  olfactorius.   There is this difference, however, 
IOO
Psychiatry.
the  bulbus  olfactorius connects directly with  the cortex; while
the  retina is united  first  to  the corpus bigeminum.   From the
retina fibres  of  the optic tract enter internodal masses, which are
joined to the cerebral  cortex by portions of the so-called brachia of
the corpora  quadrigemina.
    i.  Connections with the tractus opticus : The connection of the
                                    tractusopticus with the corpus
                                    geniculatum externum (Figs.
                                    26, 30, 32, 38) is very evident.
                                    This ganglion is not a homo-
                                    geneous mass, but consists  of
                                    gray laminae alternating with
                                    white   substance.    Properly
                                    speaking, the corpus  genicu-
                                    latum  externum is  a folded
                                    gray membrane  which  does
                                    not, like the gray  substance
                                    of the retina, unroll its entire
                                    surface, but remains enclosed
                                    in a medullary capsule.   All
                                    the fibres of this capsule are
                                    not  connected with cells  of
                                    the corpora geniculata.  The
                                    superior corpus bigeminum is
                                    joined to the corp. genie, ex-
                                    tern, by bundles  of  fibres
                                    which in man constitute the
                                    posterior portion of  the supe-
                                    rior  brachium,  or  its  well-
                                    developed  posterior  margin,
                                    and  are covered by the pul-
                                    vinar.   In  mammals whose
                                    pulvinar is scantily developed,
                                    these very  same fasciculi lie
                                    exposed on the surface ; here,
                                    moreover, the corpus genicu-
                                    latum  externum lies upon the
                        The radiating fibres from the corp. genie.
                 r9
              Fig. 39-
Oblique Section through the Brain of a Lion
 (Stained with Potassium and Gold Chloride).
    Qu. s. Superior pair of bigeminal bodies.
R. Gray substance of its surface.  Qu.i. Ob-
lique section of the inferior bigeminal body.
Rd. Radiating bundles from the corp. quadri-
gemina to the gray substance surrounding the
Sylvian  aqueduct.   L. Formation of the lem-
niscus (the line of the upper L should point to
the decussation).  A. Sylvian aqueduct. Rph.
Raphe.  P. Pes pedunculi.  Tg.  Tegmentum
of the crus.—The presence of external (dark)
lemniscal fibres, derived from higher levels of
the superior bigeminal body, is due to the ob-
liquity of the section.
optic thalamus (Forel).
extern, into the corp. bigem. super, pass into the superficial layer of
neuroglia; this layer of gray substance is more developed  in the
mammalian brain, on account of its greater (typical) wealth of con- 
Tractus Opticus.
101
nective tissue (Fig. 39, R., cortical layer, Forel).  The fasciculi bi-
gemino-genicular cs of the upper bigeminal body surround on both
sides its oblique oval ganglia, which are flattened anteriorly by lying
upon the stratum lemnisci. For this reason these ganglia present on
cross-section the appearance of plano-convex lenses.  The axes of
the superior bigeminal body intersect close behind this ganglion
and  diverge anteriorly, leaving the posterior commissure exposed
between them (Fig. 17.)  In comparison with the distinctly trans-
verse direction of the lemniscal layer, the fasciculi bigem.-geniculares,
which enter along the entire upper margin of the superior corpus
bigeminum, might be considered to be longitudinal fasciculi of the
latter (Fig. 39).  This is particularly true of those  bundles  which
are situated on the inner border of this ganglion.
   The corpora quadrigemina are connected also with the  corpus
geniculatum internum, which is united distinctly (1) to the corpus
bigeminum  superius  and (2) to the  corpus bigeminum  inferius,
through  bundles which reach  it  from  the brachium  corporis
quadrigemini inferius.
    Radiations from the tractus opticus  into the corp. geniculat. in-
ternum travel by way of the discus lentiformis, with  which the
tractus is connected (Stilling).  The discus is united toward the
rear, by a medullated pedicle, to the brachium corporis quadrigemini
inferius,  situated  on sagittal sections in  front,  and  on frontal
sections to the inner side, of the thalamus.   At the same time it
is unquestionably true that the internal geniculate body effects a
connection between the inferior brachium of the  quadrigeminal
body  and the  superior bigeminal  body;  but its  connections
with the  corpus bigeminum inferius are equally distinct, so that
the  optic tract may well appear to be connected by means  of the
discus lentiformis with the  inferior  bigeminal body.  The trans-
verse  position of the  bundles  which  surround the ganglion  of the
lower corpus bigeminum does not enable us to distinguish between
the  indirect radiations from the retina and the cortical fasciculi of
the  inferior brachium, as we  can do with  the  longitudinal optic
 radiations in the upper bigeminal  body.
    A superficial inspection of these parts would lead us to suppose that the tractus
opticus is connected directly with the corpus geniculatum internum ; but this is not
borne out by a more careful examination.
    It will  be well to divide the radiations from  the nervus and
 tractus opticus into four component parts : /. The anterior radia-
 tion into the ganglion basale. Ascending fasciculi unite this ganglion 
102
Psychiatry.
 with other regions of the  central gray substance.  2. The upper
 radiation, entering the discus lentiformis  which  lies above  the
 corpora geniculata.  This discus lentiformis enters apparently into
 connection with the radiation of the posterior longitudinal fascicu-
 lus (?). j. The outer radiation, or radiation into the corpus genicula-
 tum externum.  4. The internal radiation into the thalamus, which
 contributes, on the inner side and to the front of the corpus genicula-
 tum externum, to the formation of the latter's capsule ; and which,
 after the fashion of  the  corona radiata, enters the thalamus from
 the outer side in front of the pulvinar.  That these bundles, after
 having been interrupted in  the thalamus, are continued toward the
 corpus quadrigeminum, has not been proved.
    2.  There is a twofold, powerful connection between the corpora
 quadrigemina and  the cerebral cortex.
    a.  The  corpora quadrigemina receive  radiating fibres direct
 from the cortex (upper member  of their projection-systems).  In
 the superior bigeminal body, cortical radiations are found in the
 course of the arm  of this upper  corpus  bigeminum, constituting
 its deeper anterior layers,  which are covered  by  the  connection
 between this said brachium and the corpus geniculatum externum
 (Fig. 38, left, between T. and P.).
    The brachium of the superior  bigeminal body covers the corpora geniculata, and
 a wedge-shaped mass of thalamic substance between them ; on frontal sections this
 cuneus thalami optici intergenicularis appears triangular,
    The bundles of  its brachium connect the cerebral cortex with
 the inferior bigeminal body.
    b. The superior and inferior corpora bigemina also receive in-
 direct fibres from the cortex, inasmuch as their annexed ganglia,
 the corpora geniculata, are favored with special cortical radiations.
 The cortical fibres entering the corpus geniculatum internum may
 possibly also enter  the corpus bigem. superius,  for (as  was  stated
 above) there is a distinct  medullary connection between  these
 ganglia.   The  connections  of the external corpus  geniculatum
 with the cerebral cortex radiate from above as a stout medullary
 mass into this ganglion.  While coursing along the outer surface
 of the thalamus, this radiation contributes to the formation of the
 lattice stratum of the thalamus (vide  p. 88 and Fig. 32, above Ge).
    The frenulum, or, as it should be termed, the processus cerebelli
ad corpus quadrigeminum,  unites  both bigeminal bodies  to  the
cerebellum.
    The peripheral connections of  the corpora quadrigemina lead 
                Mid-Brain—Cortex Cerebri.            103

(1) directly into the central gray substance surrounding the aquae-
ductus  Sylvii ; from the fascicular substance of the upper corpus
bigeminum, or from its gray substance, numerous fine, radiating
bundles are developed, which, on gold preparations, seem to be the
main constituents of  that area of  the corpora quadrigemina lying
to the outer side of the lemniscal layer; these penetrate the strat.
lemnisci, and can  be traced still further into the gray wall of
the  aqueduct than is exhibited  on  Fig. 39 Rd.  The terminal
masses of the optic tract are connected in this  way with the cen-
tral  gray substance, in which fine medullary fibres, belonging to
the  origin of the  third nerve, circumscribe a nucleus confluent
with the nucleus of the fourth nerve (Fig. 39, Rd. ; Fig. 40, III.).
   3. The corpora quadrigemina are connected  indirectly with
the central  gray substance, for by giving rise to the lemniscus they
constitute the central origin of a portion of the spinal cord.  The
bundles of the lemniscus enter the ganglia from deeper layers of
the  brachium  corporis bigemini  superius,  and of the brachium
inferius.  The former portions, after broadening  on their  way
downward into the median  base  of a triangle, attain the median
line, which  they cross, and then enter into a  deeper stratum of
the  lemniscus  of the opposite side.  The latter division of  the
lemniscus  forms  a triangular group  of  bundles with an upper
median base, which lie immediately  below the  brachium anterius,
which in turn is spread most in a median direction.   The bundles
of the  lemniscus arrange  themselves in such a  way  on their
downward course that  those which lie uppermost at  the decussa-
tion are pushed furthest toward the raphe.
   The superior bigeminal body exhibits (if light is allowed  to
fall  through) a  concentric stratification  corresponding (1) to  its
layer of neuroglia; (2) to a layer of vertical fasciculi from the corp.
geniculatum externum ; (3)  to a radial  layer interwoven with
these fasciculi ; (4) to the transverse layer of the lemniscus (Fig.
39)-
   The anterior surface of the lemniscus  receives a number of
fasciculi, the origin of which is a matter of conjecture ; their par-
ticipation in the decussation of the lemniscus behind the aqueduct
is very improbable also, for they would have to cross back again
in  front of the aqueduct.   These bundles surround the aquaeduc-
tus Sylvii, and lie next and to the one side of the lemniscus, of
which Forel thinks they form a part, and which he terms fasciculi
decussations  anticce.  They form  a  convex swelling along the 
104
PsycJiiatry.
anterior margin of the aqueduct (Fig. 40, Krz B.), due to their inter-
weaving with longitudinal bundles in which  I recognize the cross-
section of the posterior commissure.
   These bundles appear to me  to spring  from  that cluster of
cells which Jacubowitsch and Virchow  likened  to  the cells of the
sympathetic, and which, at the  same  time, furnish the  central
origin of the  descending root of the fifth  nerve (Fig. 41, 5).   I
have  termed  these capsular  bundles of  the  aqueduct  quintus-
                              Fig. 40.
Transverse  Section through  the Region of the Superior Pair  of Quadrigeminal
        Bodies in a Plane Vertical to the Longitudinal Axis of the Brain.
    Big. s.  Superior bigeminal body.  A. Sylvian aqueduct.  Lms. Lemniscus (fillet)
arising from the decussation  behind the aqueduct.   Bri.  Inner protuberance and
fasciculi of  its brachium.  Krz. B.  Anterior cross-bundles of the corpus quadrigemi-
num.  x. Points to the region of decussation. Th. Bundles from the thalamus to the
Tegmentum. L. Posterior longitudinal fasciculus.  T. gris. Central cavity-gray. R.
Ill, III.  Nucleus and central roots of the oculo-motorius.  3 L.P. Root of the third
nerve and lamina perforata posterior.  R. Raphe.  P.P. Pes pedunculi.  S.S. Stra-
tum intermedium and  Soemmering's substance.  R.K. Red nucleus of the tegmentum.

columns;  perhaps  the term fasciculi  marginales aquoeducti would

be better (unbefangener).   On the cross-sections they are seen to

rise from  a  narrow margin parallel to the  aqueduct,  to spread

in rays in  order to interweave with the bundles of the posterior

commissure  mentioned above, then to attain their point of decus-

sation in  the median line by forming a narrow band between  the

posterior  longitudinal bundle and the nucleus ruber (Fig. 40, L.

and R.K.).  From  the point  of  decussation they  encircle  the 
Mid-Brain.
!Oo
nucleus ruber on the inner side, and are then lost to the front and
to the outer side of this nucleus.
    The corpus  bigeminum inferius is simpler in  structure  than
the superior bigeminal body.  The fasciculi of the brachium corp.
quadrigem. inferius, which run under and past the  corpus genicu
latum internum, give the former a white surface, traverse the gan-
glion, and bound it below  giving it the shape of a biconvex lens.
After decussating in the roof of the aquaeductus, the bundles of the
                              Fig. 41.
       Cross-Section through the Inferior Pair of Bigeminal Bodies in Man.
    Big. i.  Inferior bigeminal body.  x. Crossed transition of the inferior brachium
of the corp. bigem. into the lemniscus.  A.  Aqueduct (the outlines of which have
been unnecessarily indented and prolonged anteriorly).  L. Posterior longitudinal
fasciculus.   IV. Nucleus of fourth nerve (the line should point further outward to  the
oval space containing small cells).  4. Root of fourth nerve.  5. Descending trigeminal
root.  P. Cbl. Dcs. Decussation of the superior peduncles of the cerebellum.   Th.
Thalamic fasciculi of the tegmentum.  Lms. Lemniscus.  Lp. Posterior perforated
lamina.  S.S.  Stratum  intermedium,  and  Soemmering's  substance.  P.P. Pes
pedunculi.

above brachium enter the lower division of the quadrigeminal por-

tion of the lemniscus (Fig. 41,  Fig.  56, L.  II.).  The cross-section

of the posterior decussation of the lemniscus extends on sagittal

sections  through  the  middle  of the inferior  corpus  bigeminum

only as far as  the middle of its entire length, and  stops short at

the beginning of the frenulum.
    The mid-brain (mesencephalon), like the posterior half  of the 
io6
Psychiatry.
inter-brain (thalamencephalon), shows  four distinct layers:  I.
Posteriorly, the ganglion, Big. s., Big. i; 2. The cross-section of
the tegmentum (Figs. 40 and 41, Th., Lms., L., R.K., P. Cbl.);  3.
The stratum intermedium (S.S. ; in Fig. 41 the arrow is too short).
4. The pes pedunculi (P.P.).
    Above its point of decussation the superior peduncle  (Binde-
arm) traverses  the tegmentum in front of (ventrad)  the upper
bigeminal  body ;  during  decussation  this  cerebellar  peduncle
crosses  the tegmentum  in  front of  the lower  bigeminal body.
Ventrad  of the  lower  bigeminal  bodies  the  fasciculi  of  the
tegmentum are crowded from the  inner; side outward, owing to
the  considerable space occupied by the decussation.  The  sec-
tions of  the medullary portion of the  stratum  intermedium do
not extend as  far  to the outside, but further toward the  median
line, than the sections of the  medullary fibres  of  the  lemniscal
layer (Fig. 41).
    The composition of the tegmentum  remains quite unchanged
in the upper cross-sections of the  pons,  ventrad  of the entire
corpus quadrigeminum ;  with this  exception, however, that the
fasciculi of the  processus cerebelli ad cerebrum emerge again from
the  decussation,  proceed  to the  outer  side,  and  form  that
posterior portion of the  system of  the  superior peduncle, which
comes from the region of decussation and enters the cerebellum
(Figs. 22, 42).
   The superior peduncle,  as  it reaches  the  external surface,
appears club-shaped on cross-section (Figs. 42-45).   In the cross-
sections of the pons, at levels below the corp. quadrigeminum, this
peduncle  is powerfully developed.  On its outer surface lies the
lemniscus, which  consists  of bundles  that  on  their downward
course appear dark, like cross-sections, and  of other bundles, the
course of  which, both to the inner and  outer side of the former
group, happens to coincide with the  plane of the section.   The
outermost of these flowing bundles might Droperly  be considered
as part  of the origin of the lemniscus from  the lower corpus
bigeminum ; the inner group of bundles is undoubtedly part of
the inferior lemniscus, which ascends from the vermis superior of
the cerebellum, through  the valvula cerebri,  to a position above
the processus  ad  cerebrum,  and  is transformed  in the medulla
spinalis  into a  fasciculus of  the  lateral column, immediately in
front of   the posterior cornu (Figs. 23  and 54, LS).  The cross-
sections of  the thalamic bundles seem  to  be surrounded by the 
Oculomotor Nucleus.
107
sup. peduncles, and deserve to be termed the thalamic area of the
posterior division of the pons.
    Before  giving  an  account of our present knowledge of the
course the  fibres take from the brain-trunk to the spinal cord, we
will take note of the relations of the gray substance to the nerve-
nuclei, down to the point at which the eighth nerve emerges from
the brain substance.   On gold preparations from the infantile
brain (Figs. 43-46) the gray substance seems to be  a barren base-
ment substance.
    On sections through the brain-trunk at the level of the upper
corpus bigeminum, the aquaeductus  Sylvii was seen  to be sur-
rounded by a gray substance;  and the gray substance of its
anterior wall could well be  compared with the anterior horn of
the spinal  cord, into  which this gray substance is ultimately pro-
longed.
    The nuclei of  the third nerve (Fig. 40, III.) are bounded by
fibres which reach the central gray substance after passing from the
crus cerebri of the opposite side through the  raphe, and which in
describing  delicate, posteriorly convex arches, surround and pene-
trate an oblique-oval group of nerve-cells.
    From this nucleus, which remains confluent with the rest of
the gray substance in  spite of its well-defined  boundary lines, stout
root-bundles of the third nerve emerge (Fig.  40, 3), which turn to
the front and are slightly concave toward  the raphe;  these roots
either surround the red nucleus of the tegmentum, or lie on its
inner side.   The innermost of those bundles which pass into the
raphe approach close to the aquaeductus, between the nuclei of the
third nerves, and there divide into a  number of  diverging fibres.
It is as difficult to trace these to their final termination, as it is to
follow up those radiating bundles which seem to approach  them
from the corpus quadrigeminum.  Cross-sections  of descending
root-fibres  of  the  fifth nerve lie immediately next to those  mar-
ginal bundles (p. 104) which enter the decussation in the tegmen-
tum, in front of the aquaeductus Sylvii.   These descending roots
-pring from clusters of vesicular cells.  The  shape  of these cells,
which possess distinct sheaths, we said above could be compared
to  the shape  of  the sympathetic  ganglion cells.   They take
no part in  the gray reticulum of  fibres surrounding the aquaeduc-
tus, into which optic fibres, and the prolongations of third nerve-
cells enter.
    On cross-sections, through  the plane  of  the  lower  bigeminal 
108                        Psychiatry.
body (Fig. 41, L., IV.), the area  occupied  by the  nucleus of the
third nerve seems imbedded in a posterior groove of the posterior
longitudinal  bundle  (nucleus  of the fourth nerve).  From this
nucleus bundles pass to the outside, and along the margin of the
aquaeductus  Sylvii, which take  an obliquely descending course
from the anterior periphery of this nucleus to its posterior periph-
ery.  In  a  part of this course  they necessarily on cross-section
present the appearance of circular formations at the lateral margins
                                        S.cin.
                              Fig. 42.
   Cross-Section through the Pons, at the Level of the Exit of the Fourth Nerve.
   x. Decussation of the fourth-nerve roots, in the velum medullare.  4, 4. Fourth-
nerve roots.  5. Descending trigeminal nucleus bordering anteriorly on the posterior
longitudinal  fasciculus,  Th.  P.Clb.  Superior peduncle of cerebellum.   S.fecz.
Its fasciculi lying one above the other.  Dcs. Decussation of the peduncles.  Lms.
Lemniscus.  St. Lms. Lemniscal layer, including the stratum intermedium.   F.trv.
p.  Transverse bundles of pons.   Ped.  Peduncular fasciculi.   S.cin.  Gray floor of
fourth ventricle (substantiacinerea).
of this central gray substance.    These ring-like fasciculi are situ-
ated to the inside also of the trigeminal root in the gray substance
surrounding the aqueduct.   Finally they decussate and enter the
valvula cerebri, immediately below the corp. quadrig., from which
they emerge free  (Fig. 42, 4,  4).   New  additional bundles  from
the  round cells in the region of the lower bigeminal body render
the crescent of the fifth nerve more distinct, which at the level  of
the  emergence of  the fourth  nerve  forms  the outermost  part
of the anterior boundary of the aqueduct.  The posterior longitu- 
Substantia Fcrruginosa.
109
dinal bundles  abut  upon the  median  portion  of the  aqueduct.
The velum medullare forms its posterior boundary.   At this level
a new formation of cells is discovered within the gray substance—
i.  e., the  substantia fcrruginosa  (Fig.  43, S. foa.).   This  is con-
nected with bundles  which run as far as the  raphe  in  a trans-
verse direction parallel  to the  gray substance.  Near the raphe
large nerve  cells  are  liberally  interspersed between,  and inter-
Sbsl.cir
                                    fppl.
                               Fig. 43-
     Potassium and Gold-Chloride Preparation from Brain of the New-Born.
Cross-Section through the Pons at the Level of the Emergence of the Small Trigemi-
       nal Root (the Right Half of the Section Representing a Higher Level
                             than the Left).
    Cbl Cerebellum.  v.  IV.  Fourth ventricle.   sbst.  cir. Gray floor of  fourth
ventricle  nucl. m. Nucleus of the small (inner) fifth-nerve root. S. gl. Gelatinous sub
stance with (sm ) bundles of the large fifth-nerve root. Lms. Lemniscal layer and stra-
mmTnermedSm.  Br. p. Bundles from the brachium pontis  fp  la. Anterior longitu-
dinal bundles of pons.   fppl.  Interwoven transverse bundles of pons.   fppr.  Deep
dinal bundles £pfnf «ons  \  Laree fifth-nerve root. Th. Thalamic area of posterior
£So^                         /d- Descending fifth-nerve root  (The
d^rclublhaped section of the superior cerebellar penduncles are not lettered.)
woven with, the fibres of  the posterior longitudinal bundle.  A
transverse commissure  or decussation apparently  establishes a
connection between  these cells.  It is certain that the dark cells
under the locus cceruleus on the floor of the fourth ventricle (Fig.
Atf connect in this way with fibres of the raphe, which are derived
from  the anterior  division of  the pons  and  lend a medullary 
I IO
Psychiatry.
 appearance to its posterior division.   These fibres may be looked
 upon as originating in the pyramidal tract.
    The substantia ferruginea is a powerful mass extending from
 the lower corpus bigeminum  nearly  as  far as the lower half of
 the pons  (Stilling).  At its periphery  it is connected with  the
 innermost bundles  of  the large root of the  fifth  nerve.   The
 nucleus of origin  of the small fifth-nerve  root is situated pos-
 teriorly from, and to the inner  side of, the large fifth-nerve root
 (Fig. 43, nucl. mi).   From this smaller root arise the inner bundles
 of the entire fifth-nerve  root (Fig. 43, sm.).  The central nuclei of
 that massive portion of the large trigeminal root, which originates
 and emerges at the same level, presents a clustered arrangement of
 minute  heaps of small-celled  gray  gelatinous substances  (Fig.
 43, S. gl.).
    At the level at which the entire trigeminal nerve emerges (Figs.
 43  and 44—5) we distinguish from within outwards: (1) an inner
 large-celled trigeminal nucleus, with the small root;  (2) bundles
 passing  from within outward, and between the cross-section  of
 posterior longitudinal bundles, which bundles are derived from the
 subst. ferruginea of the  opposite side, and belong to the descend-
 ing roots; (3) the upper descending  trigeminal root (the familiar
 small  crescent—Figs. 43—rd,  44,  r.dest.);  (4)  the  bundles  of
 the ascending trigeminal root, which evidently originate from a
 nucleus  situated below  the emergence of the fifth  nerve—this
 nucleus extending to the lower end of the tuberculum cinereum
 Rolando in the oblongata.  The trigeminal root encircles its gray
 nucleus with medullary  substance, which  becomes attenuated  as
 it proceeds downwards, and is finally lost in the spinal caput  cornu
posterioris (Stilling).  This  root is of very considerable size; (5)
 Cerebellar fasciculi also join the large trigeminal root.   These fas-
 ciculi lie either immediately upon the outer edge of the processus
 cerebelli ad cerebrum, or actually invade the latter; (6) the large
 trigeminal root is joined beyond a question by cerebellar bundles,
 which are closely moulded to the outside of the superior peduncle
 (Stilling), and possibly invade the latter.
    Below  and indeed within  the planes at which the fifth nerve
 emerges, begins the central  origin of the sixth and seventh nerves.
 At  the highest level we notice decussating bundles  leaving the
 raphe  to  enter the  root of the facial nerve (Fig. 45, right  side).
 Dorsad of the bundles from  the raphe lies a circular spindle-shaped
 section, the genu facialis,  the  bundles  of which arise from the 
Facial and Abducejis lYerves.              111
anterior facial nucleus, which is situated in an  anterior inferior
portion of the pons (Fig. 45 ncl. 7).   The knee of the facial nerve
is  made  up  of root  bundles, which curve around the common
nucleus  of the sixth  and seventh nerves, and,  in so doing,  pre-
sent  a convex surface  facing dorsad.  For this  reason, the knee
seems separated  from  the  emerging root  (Fig. 45,  left,  g) on
sections which are laid below this connecting arch, between the
                (From the same series as Fig. 43.)

Cross-Section through the Pons at the Level of the Exit of large V. roots.
    P. Chi., nucl.  Superior peduncles of cerebullum.  V. 4.  Fourth ventricle,  r.
dest.  Descending root of V. nerve.  Sf. 5.   Trigeminal root from sutstantia ferru-
ginosa.  Sg.  Substantia gelatinosa.  5, Large V. root.  Ol. s.  Superior olive.  Br.
p.   Brachium pontis.  Tr. prf.  Deep transverse bundles of brachium pontis. F. p.
l.a.  Anterior  longitudinal  fasciculus.   P.tr.spf.  Superficial  transverse  bundles.
Fibr. ecfl.  Circumflex fibres of pons.   Lms. Lemniscal  layer and stratum inter-
medium. 6 VI. roots.  Th.  Thalamic area of posterior pons segment.  L. Posterior
longitudinal fasciculus.  7. Facial roots.

knee and the emerging portions of the root.   The genu, descend-

in"- vertically, appears cut on cross-sections.  The common nucleus

of the sixth and  seventh  nerves lies between the  two portions  of

the root.   The large and radiating cells of this nucleus are similar

to those in the nuclei of the third,  fourth, and in the outer nucleus

of the fifth nerve.  The roots of  the sixth nerve bend outward,

and undoubtedly connect with the cells of this common nucleus 
112                        Psychiatry.


(Deiters).   It is equally certain that the root of the seventh nerve
also connects with a lesser portion of this nucleus, the lateral por-
tions being taken up entirely with the emerging fibres of the facial,
which on their course from the nucleus forward constitute a much
narrower bundle.   Like all  nerve-nuclei, this nucleus is in reality
nothing more  than  the  more compact portion of a formation of
cells  scattered all around it (Deiters).   From  this  nucleus fibrae
arcuatae pass into the  raphe, thus connecting this nucleus with
Stained with Potassium and Gold Chloride.
Cross-Section at  the Level of  Emergence  of Seventh  Nerve.  (The  Right Side
                 Represents a Higher Level than the Left.)

    Cbl. cerebellum,  nc.  Dentate  nucleus of  cerebellum,  ncl.  6 + 7.  Joint
nucleus of sixth and seventh nerves,  g. Central knee of facial nerve.  L. Region of
posterior longitudinal fasciculus.  Th. Thalamic area of posterior pons segment.  8.
Fibres of auditory nerves.  7. Root of facial nerve.  6. Root of sixth nerve.  Py.
Bundles of the  pyramid.  R. Raphe,  fa. Anterior column.  Ols. Superior olive.
ncl. 7.  Anterior facial nucleus.  Lms. Lemniscal layer and  stratum  intermedium.
B. p.  Brachium pontis.  5. Ascending trigeminal root.  S. gl. Gelatinous substance
in the ascending trigeminal root.  V. IV.  Fourth ventricle.

topographically  higher centres.   There  appear to  be  commis-

sures  also  uniting  both  nuclei.   The anterior  facial nucleus  is

distinct in higher facial  planes,  increases in size as we proceed

downward, and is  traversed by the root-fibres coming  from the

genu (Fig. 45. ncl. 7;  Fig. 46, ncl. 7, and  on the right to the inner

side of  7).  This nucleus lies close to  the trunk of  the facial,

which passes between it and the ascending trigeminal root.   The 
Nervus Facialis.                    113
knee gathers from the anterior nucleus a number of fine parallel
bundles, and at its upper level of origin does not yet present a
compact mass  to the  front of  the tubular gray (Fig. 46 ;  compare
right and left).  The nerve  fibres from the lower nucleus do not
narrow down  at once  towards the genu, but the external fibres
form a loose  capsule around  the ventral surface of the posterior
nucleus.   It is possible also that root-fibres pass directly and ob-
liquely outward and  forward  from  the  lower  nucleus  to  the
emerging portion of the facial root.
    Analogous to the descending, vertical, and ascending  roots of
the trigeminal nerve, we find that those facial bundles which issue
                              Fig. 46.
                 Stained with Potassium and Gold Chloride.
Cross-Section through the Highest Level at which the Auditory Nerve Emerges-
     The Right Half of Specimen Represents a Higher Level than the Left.
    ncl f. Nucleus tecti (Stilling).  V  IV. Fourth ventricle,  g  Knee of  facial
nerve  'pdi. Internal division of the cerebellar peduncle,  ncl. 7. Lower nucleus of
seventh nerve, which receives the bundles from the knee of the facial, ol. 1. Inferior
olive  P  Pons.  Py. Pyramid.  01. s. Superior olive.  7. Iacial root.   5. Ascend-
ing root "of trigeminus.  8.  Auditory root not designated on left side.  Br. p.
Brachium pontis.  (Medipedunculus.— Wilder).
from the raphe, are in reality descending fasciculi, arising possibly
from the internal capsule, but certainly from the nucleus lenticu-
laris.  The  planes of origin  and emergence are identical in the
case of these  roots which  enter the posterior nucleus ; but  the
root derived from the inferior nucleus of the  facial, the genu n.
facialis,  is an ascending, root (as is evident from fig. 46).  The
bundles emerging  from the  lower nucleus  pass toward the gray 
ii4
Psychiatry.
substance, anteriorly from this, and move  upward as the ge7iu n.
facialis;  the  knee  is  continued into the emerging  root.   The
genu has the  shape of a horse-shoe; its lower  branch  travels
from the inferior nucleus to the gray substance, its upper  branch
from the middle of the gray substance forward.  The knee of the
facial nerve  constitutes the middle piece and  connecting link be-
tween these two branches of the horse-shoe  formation, lying one
over the  other.  This formation  is placed diagonally in  each half
of the posterior  division  of the pons.  The connecting  arches
converge in a median and  posterior direction.   The facial does
not  run parallel to  the anterior roots of  the spinal cord, as do
the  third, the  sixth, and the twelfth nerves, which form the ex-
      Preparalion Stained with Potass. Gold Chloride.  From the Newborn.
Cross-Section through the Lower Level of the Exit of the Auditory Nerve—The Right
               Half Represents a Higher Level than the Left.
    NC.  Dentate nucleus of  cerebellum.   Bp. Brachium pontis.   R. Rst. Corpus
restiforme.  e. Fibrae arcuatas from the corpus restiforme.  5. Ascending trigeminal
root. oli. Inferior olivary body.  R. Raphe beginning between the pyramids.  Z.
Stratum zonale.  nclSa.  Anterior acoustic  nucleus, v. IV.  Fourth ventricle.  8'.
External  auditory nucleus. 8. Inner acoustic nucleus.  T. Eminentia teres.   flf8.
Bundles of the flocculus and the external acoustic root which are not separated from
each other.
ternal  boundary of  the region of the  anterior  columns;  it  lies
to the outside of the lateral columns, next to the formation analo-
gous to the posterior horn—i. e., the substantia gelatinosa of the
asc. trigeminal  root.
    On  sections through  the level of  the  origin  of the facial
nerve  the  gray  substance exhibits   two  prominences.   The
inner prominence,  the  eminentia teres, is  due  to  the  common 
Cerebellum.
"5
 nucleus of the sixth and seventh nerves ;  the external prominence
 is to be placed to the  account of the auditory  nucleus (Fig. 45).
 The origin (?) of the eighth  nerve, however, can only be studied
 in connection with the region surrounding it, including the cere-
 bellum,
            THE CEREBELLUM AND  THE N. ACUSTICUS.
    It is not  my intention to give an exhaustive account of the
 minute anatomy of the cerebellum ; for many gaps in our present
 knowledge of the subject will  undoubtedly be filled  up  by the
 great monograph which Stilling is now preparing.1   It would be
 a  gratuitous and unnecessary task to attempt to anticipate the
 work of such a great master.
    We have already described cerebellar bundles in the internal
 capsule in the  form  of  radiations from the cerebrum into the
 nucleus ruber of the tegmentum.  We have observed the processus
 cerebelli ad cerebrum  emerging from the  red nucleus of  the
 opposite  side ;  we noticed, furthermore, the  unfolding  of the
frenulum  into the vermis superior, after passing  through the ante-
 rior velum medullare, and in the vellum medullare we  found the
 cerebellar portion of the lemniscus.
    The bundles of the brachium  pontis (processus cerebelli  ad
 pontem) consist (1) of a superficial layer, (2) of the interwoven
 layer which gives rise  to secondary bundles  in the pes  pedunculi,
 and (3) of deep, transverse  fasciculi.  These bundles  lie  to the
 front of the stratum intermedium, which is joined by the inner
 bundles of the  crus  arising from  the ansa lenticularis.   Gray
 substance with its ganglion cells, which invade the entire anterior
 division of the  pons, reduce the  volume  of  the crus proper.
 Through the mediation of these cells, and a gradual reduction of
 its volume, the bundles of the crus are transformed into a  cross-
 section of the  pyramidal tracts, and then enter the brachium
 pontis.  For this reason alone the bundles of the brachium pontis
 are not commissural  fibres,  but the  continuations of recurrent
 fibres of the crus.
   Their commissural  nature is disproved furthermore by the fact
that a large number of bundles of the brachium pontis pass on the
outside around groups  of peduncular fasciculi (Figs. 43, 44).  Both
ends of this circular formation turn toward the opposite brachium
pontis, and belong to different levels of the pons, passing, as they
do, either from the superficial  layer to the interwoven layer, or
1 This work was completed in 1S78.—S. 
n6
Psychiatry.
from  this layer into the layer of  deep, transverse fibres.   Each
arch of the fibrce circumflexoe pontis exhibits  two branches, one
of which  enters  the crus after taking a superficial course from
the brachium pontis of the  opposite side ;  while the other leaves
the pedunculus  again, mingling with gray substance and emerging
through the opposite brachium pontis.
    Its processus  ad pontem forms  a considerable mass  on the
outer side of the  meditullium of the cerebellum.  The cerebellum,
like the cerebrum, is surrounded by a mantle  of convoluted gray
substance, the cerebellar cortex, which serves as the point of
origin of its  medullary substance.  It is developed from the pos-
terior wall of the posterior (fcetal) cerebral vesicle.
    Between the ends of the large horizontal fissure lies the hylus,
which permits the entrance of the four medullary processes  into
the gray mantle of the cerebellar cortex.  Owing to the medullary
substance of the  velum medullare (Marksegel) and of the processus
cerebelli ad  cerebrum entering  through  the  hylus,  the  vermis
superior presents a white anterior surface (Fig. 55).
    Up to the date of  Stilling's great investigations of the cere-
bellum, the only gray cerebellar masses known were the cortex
and the nucleus dentatus. We are indebted to him for our knowl-
edge of the  ganglia  tecti, which  unite  in the median line, and of
other nuclei, to which he refers in  a preliminary notice  published
in the Centralblatt fur die Medicinischen Wissenschaften.
    The cortex of the cerebellum consists of three  layers : an ex-
ternal gray layer  proper and an inner grayish-red layer,  which are
distinguishable by the naked eye. On microscopical examination of
the cortex, we discover between these two layers another layer con-
taining cells of Purkinje.  The basis substance of the cerebral cor-
tex, of the ganglia, and of the cerebellar cortex remains the same
throughout.   According to Obersteiner the cerebellar  cortex in
the child is covered  by a layer of formative cells, which  are trans-
formed  into spindle-shaped  fibrils, thus constituting an innermost
stratum of the pia  mater.  The gray layer proper exhibits small
nerve-cells,  the destructible protoplasm of which often makes it
difficult to distinguish between these and non-ganglionic elements.
In addition  to these generally triangular granules, there are,  near
the grayish-red granular layer, transverse, spindle-shaped  bodies,
which run parallel to the convolutions around  the fissure between
two convolutions, but, unlike  the cerebral, spindle-shaped cells, lie
to the outside instead of to  the inside of the granular layer.   I 
Cortex Ccrebelli.
117
H>
agree with Stilling in regarding the cells of the granular layer as
multipolar ganglion-cells ;  but, instead of looking upon the widely
separated groups of cells as the  breeding-place of regenerating
cells, I would prefer to assume a connection between them and the
ramifications of the inner processes of  the cells of Purkinje.  In
doing this, I  must  demur, however, to the  view of Koschewni-
koff, who believes that one solitary, non-ramifying process issues
from the inner side of  Purkinje's cells.  The large cells of Pur-
kinje, which occur at  con-
siderable distances apart,
and form but a single row,
are connected  with the in-
ternal and external layers l a
of  the cerebellar   cortex.
The external powerful pro-
cesses of  these  cells  are
formed by a gradual atten-
uation of the latter's pro-
toplasm.   They   branch
dichotomously  at  first
around the sulcus between
two  convolutions,  at  an
angle  of nearly  180  de-
grees.   From  these main
branches many others are
sent off at right angles;
 these undergo secondary
ramifications like the an-
tlers of a deer, and are con-
tinued into, and give the
appearance of parallel stria-
     ,  ,1     ,1        r   I a and I b.  Gray layer proper; (i b with spindle-
tion tO tne OUter layers OI cellsand transverse fibres.) 2. Cells of Purkinje, 3.
 the cortex.  They seem to Granular layer, m. Medullary substance.
ramify in those planes of  the cortex which belong to one of the
delicate, separable laminae of the  medullary  substance.  Accord-
ing to Hadlich these processes take a recurrent course when near
 the  cortical  surface.    The  appearance  of  recurrrent  processes
 may be due to the terminal ramifications turning back in order  to
unite with the triangular  cells  of  the  external layer.   The  inner
halves of the cells  of  Purkinje are vesicular in  shape.   Purkinje
compared these large cells to field-flasks—ampullae,—from the neck

              Fig. 48.
Transparent Section of the Cerebellar Cortex
              of Man. 
n8
Psychiatry.
of which  the  strong process just described would issue.  Those
processes which issue from the bottom of the flask are much more
delicate, and though they may give rise to more than one process
(contrary to Purkinje's opinion) they ramify but little.  They split
up soon into  a  network  of fibres connected with  the granular
layer.  The medullary fibres of the cerebellum have, in  all likeli-
hood, a twofold origin in  the cerebellar cortex: (i) from recur-
rent, ramified branches of the external process  of the cells of
Purkinje; and (2) from the network  of the  granular layer into
which the inner processes of these cells of Purkinje enter.
   The nucleus  dentatus of the  cerebellum is traversed by radiat-
ing fibres, which probably connect the bundles of the processus ad
cerebrum  with the cells of this body.  At  the level of the facial
and at the upper levels of  the auditory nerve, the nucleus denta-
tus is  separated as yet from the  processus ad  cerebrum, and
lies very  close to the lateral wall  of  the oblongata, after it has
become distinct  from the trunk  formations in the oblongata.  At
the level of the central origin of the auditory nerve, the processus
ad cerebrum is crowded away from the lateral wall of the floor of
the iv. ventricle: (1) by bundles which decussate in passing through
the ganglia tecti; and (2) by another group of  bundles which
covers the nucleus dentatus (Fig. 46, left, to the outside of pdi.); (3}
by still  another, which at higher levels was situated between the
nucleus dentatus and  the processus ad  cerebrum (Fig. 45, Cbl.).
These  groups, constituting the  corpus restiforme lie to the outer
side of the cross-sections of the ascending trigeminal root.  At the
level of the ganglion tecti (Fig. 46), the first group of bundles passes
either, without crossing, to the outer  side of this ganglion, or, after
decussating through the ganglion tecti on the inner side, downward
to the oblongata.  These bundles appear truncated on  the outer
side of the auditory nucleus in the gray substance.   They intersect
with bundles  of the  auditory root which, entering In  a reverse
direction from the anterior surface of the trunk, turn inward on the
outer side  of the ascending trigeminal root, and after mingling
with the former are cut across also.   At  the junction of these con-
verging bundles from  the cerebellum and  from the auditory root,
an  angle  is formed  opening outward.   This angle is completely
filled by the corpus restiforme, which descends from the region of
the nucleus dentatus cerebelli, and edges its way into this angle.
These bundles,  which have been first  described  as entering  the
gray auditory nucleus to the inner side of the corpus restiforme,
occupy the area of Clarke's external auditory nucleus. 
Corpus Restiforme.                 11 q
   In his publications on the lingula and the lobulus centralis, Stil-
ling has shown that the neighboring cerebellar convolutions are
united to one another by wreath-shaped bundles, and that on sagit-
tal sections of the vermis we perceive arciform fibres connecting
various  regions of the cortex;  these arciform  fibres varying in
length  and running  in  different  directions.   These  arciform
bundles lie  nearer to  the  cortical surface  than a certain system
of fibres which Stilling has described as transverse and decus-
sating fibres.   The cortex of the cerebellum possesses single and
general  systems of  association bundles, similar to those of the
cerebral cortex.
   The corpus restiforme must  be divided  into two parts :  one
part  belonging to the pons, and the  other to the oblongata.
That portion of the posterior division of the pons which is not
crowded out  by arciform  bundles  emanating  from the nerve-
nuclei, and  taking the place of the gray substance in the raphe,
is occupied  by transverse fibrce arcuatce  starting from the corpus
restiforme.  Above the auditory root they emerge distinctly from
that portion of the corpus restiforme which is  situated between
the processus ad cerebrum and the nucleus dentatus, which passes
through the trigeminal region at the level of the superior olivary
body, and  sends forth that superficial stratum  of bundles which
answers to the corpus trapezoides in animals (Fig. 45, Ols., Lms.,
5).   These  bundles appear  at  first  to course to the front of the
superior olivary body, and after crossing each  other at an acute
angle, to enter the latter body.   It is not as evident in man as it is
in animals  that pedunculated bundles  issue from  the superior
olivary  body on the inner side of  the ascending trigeminal  root;
and that these bundles course backward  between the nucleus and
root of  the eighth nerve.  This relation bears a striking resem-
blance to that existing between the corpus, restiforme and the
lower olivary  body.   Longitudinal bundles  from the region of the
funiculus lateralis are also connected with the superior olivary
body; as is exhibited on longitudinal sections of the brain-trunk,
these longitudinal bundles lie behind the layer of the lemniscus in
which the lower  olivary body  is lodged.  The lower  portion of
the  corpus restiforme—that part belonging to  the oblongata—is
separated in the cerebellum, by the nucleus dentatus, from the other
portion belonging to the pons.  This lower restiform body, which
is a prominent feature on the surface of the medulla, together with
its  stratum zonale, we  described  above as it edges its  way be- 
120
PsycJiiatry.
 tween the cerebellar and the auditory bundles into the section of
 the external auditory nucleus.   The innermost cerebellar bundles,
 which pass down to the oblongata, descend far down in the com-
 pany of  the anterior  roots of the  auditory nerve,  through the
 area of the external auditory  nucleus.  They are situated to the
 inner side of the corpus restiforme (Fig. 49, Rsl., 8',  R.).   These
 bundles are evidently related to the auditory root.
    Examination reveals that these cerebellar bundles in the audi-
• tory  nucleus are part  also  of the auditory nerve-tract.   On  its
 course between its cerebellar origin and its central root, the audi-
 tory tract receives an addition  in  the form of the  fibrae arcuatae.
 The  fibrae arcuatae  cross the median line,  and undergo  decus-
 sation between a large portion of auditory  roots and  the cere-
 bellum.   Auditory bundles may indeed be divided into such which
 decussate in the  oblongata  and such which do not  decussate in
 that organ.
    Crossed auditory bundles.
    a.  External auditory bundles, striae  medullares.   They pass
 either directly to the point of  decussation—the raphe,—in order
 to enter Clarke's nucleus (Fig. 49, 8') through the intervention of
 fibrae arcuatae,  or  they pass from the outer side  into the cross-sec-
 tion of Clarke's nucleus (Figs. 50, 52, left), which, connecting with
 fibrae propriae,  conduct the  former to Clarke's nucleus of the
 opposite  side  (Fig.  52, right).  The external  auditory bundles
 surround   the  inner limiting  bundles  of  Clarke's nucleus, and
 then  divide  up into  posterior bundles, travelling through  a part
 or the  whole  of  the inner  auditory nucleus, and as far as the
 raphe, and into anterior fibrae arcuatae which pass far front in the
 raphe (Fig. 49,  right and left).
    In the upper levels of the oblongata almost all fibrae arcuatae
 constitute part of the auditory tract.  These lend a medullary ap-
 pearance  to the whole of the raphe, through which they pass, and
 the stratum zonale even seems to be derived from bundles coming
 from Clarke's nucleus (Fig. 49, se.).
    b. The inner crossed auditory bundles  form in   conjunction
 with  cerebellar bundles cross-sections in the area of  Clarke's
 nucleus.  They descend to within half the height of the hypo-
 glossal  triangle.  Throughout this  area these  bundles are con-
 nected  with fibrae arcuatae,  y.  The acoustic  bundles, as well
 as  the  cerebellar  bundles,  after  they have descended  so far,
 may form either simple commissures with the ends  of the  fibrae 
Nervus Acusticus.
121
arcuatae, or they may in passing through the  raphe connect  the
cerebellar bundles  of one side with the acoustic  bundles of  the
opposite side.  Of these two possibilities, the latter is the  more
plausible.   The existence of commissural fibres in the raphe  has
not been proved at all.   In  descending, the inner crossed  acoustic
tract extends from the region of origin of the facial, through that
of the tenth,  to the central  origin of  the twelfth  nerve.  The
raphe, as well  as the area of the acoustic arched fibres  y, contains
                                Fig. 49.
                  Stained with Potassium and Gold Chloride.

Section through the  Level of Emergence of Auditory Nerve.  Brain of a New-born
       Infant.  (The Right Half  Represents a Higher Level than the Left.)
    Bp. Brachium pontis.   NC.  Dentate nucleus of cerebellum  surrounding the
superior peduncles of the cerebellum.  To the inner side of the radiation of the su-
perior cerebellar peduncles into this gray lamina there lies a dentate ganglion, which I
have termed the accessory nucleus  ol the nucleus dentatus.  v. IV. Fourth ventricle.
8.  Inner auditory nucleus  8 ' .Externalauditory nucleus (Clarke's),  fl + 8.  Medullary
substance of the  flocculus and an external auditory root.  On the left side the
pedunculus flocculi  is  distinctly separated  from the external auditory root.  Rsl.
Left corpus restiforme, with the inner  acoustic root resting upon the median mar-
gin.  5. Ascending  trigeminal  root.  nclSa.  Anterior  auditory nucleus (Stilling).
oli.  Inferior olivary  body.   12. Hypoglossal root.   R.  Raphe.   £.  Most anterior
fibrae arcuatas.  T. Eminentia; teres.

ganglion  cells which  are connected with  the  network of fibres

issuing from the above-mentioned motor-nuclei, and which Deiters

supposes to be scattered ganglion cells belonging  to the nuclei of

the nerve-roots.
    The uncrossed acoustic bundles are the following:

    The inner acoustic bundles ' are connected with the cerebellum

    1 I prefer to speak of acoustic bundles rather than  of acoustic nerve-roots, for
their value as nerve-roots is, as Kolliker has shown, as questionable as in the case of
the optic nerve and the so-called olfactory nerves. 
122
Psychiatry.
directly by  means  of fibres  which ascend  toward the ganglion
tecti, invading and  covering the processus ad  cerebrum (Fig. 46,
right).   There is a partial interruption of  fibres through  nerve
cells on the external  barren portion of Clarke's nucleus (Fig. 49
between 8'  and  Rs.l., left).   Acoustic bundles  bend  over also
directly into  the corpus restiforme, and particularly so, near the
lower edge  of this body.
    Finally there is the anterior acoustic nucleus  of Stilling lying
between the inner acoustic bundles, the corpus restiforme and the
Stained with Potassium  Gold Chloride.
Section through Oblongata of New-born.  (Left Side Represents  a Higher Level.)

    A. Internal auditory nucleus. 8'8. External auditory nucleus ; external and internal
auditory root  on  left side.  R, C. R. Corpus restiforme.  v. Ascending trigeminal
root, to the outer side of  the gelatinous substance.   The trigeminal section is
traversed by glosso-pharyngeal roots, oi., oi. Olive and accessory olivary body. Hypo-
glossal roots emanating from nuclei in the eminentia teres disappear in the olivary
body.  a. Fibras  arcuatae from the nuclei of the tenth nerves.  (These nuclei consti-
tute the prominence between the eminentia  teres (hypoglossal nucleus) and  the inner
auditory nucleus, and this prominence is very slight on the left.)  (5. Fibne arcuatse from
the ascending vago-glosso-pharyngeal root,  y. Fibrse arcuata? from  the external audi-
tory nuclei. 6\ Fibrae arcuatoe from the post, column.   Hst. Posterior column.

flocculus (or  the  medullary substance  of  the  cerebellum, Fig.

49, ncl8a).   This nucleus receives those parts  of  these bundles

which take an outward course, and then again it is unquestiona-

bly connected with the medullary substance of the  cerebellum.

      EXIT OF THE 9, IO, II, AND 12  PAIRS OF CEREBRAL NERVES.

    With the disappearance of  the fasciculi of the pons the pyra-

midal tracts lie immediately to the front of the  anterior columns,

from which they are  not distinctly separable.   The gray substance

of this region  exhibits three  prominences:  (1) the eminentia teres; 
Nerve Roots of Oblongata.                12 3
(2) the posterior column of origin of the ninth, tenth, and eleventh
cerebral nerves—the ala cinerea—pneumogastric  nucleus ;  (3) the
internal acoustic nucleus (Figs. 50 and 51).
    The eminentia teres contains heaps of nuclei from which circu-
lar bundles emanate, which  encircle their own cells of origin, and
ultimately give  rise to roots of the  hypoglossal nerve (Figs. 50
and 51); but the superficial margin of the eminentia teres also con-
tains smaller cells, through which definite portions of the root of
Stained with Potass, and Gold Chloride.  New-born.
 Transparent Section from the Oblongata.  (Left Half Represents a Higher Level.)

    XII. Hypoglossal nuclei.  12. Hypoglossal roots.   The lateral 12 exhibits fibres
from the nucleus XII., which are scattered in among the gray substance of the funicu-
lus lateralis (\,}).  8'8'. External auditory nuclei.  Pst., list. Posterior columns.  A.
(ought to be further to the outside) Ala cinerea (nucleus of vagus). 8. (ought to be far-
ther to the outside) Internal auditory nucleus.  CR.,  CR. Corpora restiformia.  g.
Substantia gelatinosa surrounded by the ascending trigeminal root.   On the left to the
inner and outer side of g, the vagus roots.   O., oi., oe. Olive, internal and external
accessory olives,  a.  Fibrae arcuatae from the nucleus of  vagus.  /?. Fibrae arcuatae
from the ascending vago-glosso-pharyngeal roots,  y. From the external auditory nu-
cleus.   8.  From the posterior column,  e. From the corp. restiforme.  Z. Stratum
zonale.

the tenth nerve pass on their way to the raphe.  These fibres pass

around  the  hypoglossal  cells  in  a circle presenting  a posterior

convexity.   The  joint nucleus of the ninth and  tenth  nerves,

which disappears toward  the  inner side of the auditory nucleus

in the plane of  the  rhomboid fossa,  does  not approach  at all

near  the  surface on  sections at   levels immediately  below the

striae transversae.   On such sections it is merely a mass of gray sub-

stance, which takes a  brighter carmine staining than the neighbor-

ing gray substance (" eminentia teres and auditory nucleus "), and

gives rise, first of all, to roots of the glosso-pharyngeal nerve.   At 
124
Psychiatry.
lower levels (Fig. 50,  left) a small  nucleus of  the tenth nerve  is
perceptible.  A very large  part of  this nerve at its  origin seems
on  carmine preparations  to form  a  groove about  a number of
small cells (Fig. 50, glosso-pharyngeal  nucleus on the left).   This
section of medullary fibres represents not only an ascending root
of the glosso-pharyngeal  nerve, but also of the tenth nerve, from
which delicate  fibrils  are unrolled  throughout  its entire  length ;
these delicate fibrils, as they are unrolled, mingling with small cells.
This ascending root lies on  the gray floor close to the trigeminal
root (Fig.  50, right;  Figs.  51,  52).  The ascending trigeminal
root has been justly compared to  a posterior  root  of  the spinal
cord, and the hypoglossal  nerve to an anterior spinal-cord root.
The region of the vagus is accordingly situated between these two
nerves,  which  are analogous to roots of the spinal cord.   In-
asmuch  as  it sends its fibres through the funiculus lateralis,  it
deserves  to be  termed  the lateral system.   In the  funiculus
lateralis we  find a small cluster of cells, which, as it  is  analogous
in position,  should be considered the  prolongation  of  the lower
facial nucleus, and of the motor trigeminal nucleus ; it contains
also large multipolar cells.    This is  the  motor nucleus of the
tenth nerve, or, as it has been termed, the anterior column of ori-
gin of the lateral  mixed  system.  The expression "  lateral mixed
system " was suggested by  Deiters, and might be appropriately
applied to the  central  nuclei  of  the 9th,  10th, and  nth nerves.
In reality the anterior central  nucleus  of the vagus is a nucleus of
the accessory nerve, which passes downward into the gray reticu-
lar  lateral process of the anterior horn,  from which the lowest
roots of the accessory nerve emanate.   Those  bundles of this sys-
tem which are analogous to  the posterior roots of the spinal cord
traverse the gelatinous substance of the trigeminal nerve, and are
derived from the posterior column  of  origin of this  system,  from
the ala cinerea (Fig. 51, 8).   The ascending root  arises on deeper
levels, from  fibrae arcuatae issuing from the raphe (Figs. 52, left fS).

    Roots of the vagus from the raphe course behind the hypoglossal nucleus as bun-
dles  of the  eminentia teres, while bundles from the ala cinerea  pass in front of the
hypoglossal nuclei, past the posterior columns of origin, and directly into the root of
the tenth nerve (a).  Bundles from the anterior column of origin curve knee-shaped
into  the vagus,  and from this nucleus roots appear to arise, which pass directly to the
front (radial fibres, Lenhossek).  (Fig.  51, left, in front of the fifth nerve).
    The region in which the motor  nucleus of the tenth nerve and
the hypoglossal  nucleus  are situated, though  it  appears to be a 
Cross-section of Oblongata.                125
centre  of aggregated cells, has no distinct boundaries; and  re-
sembles  the  region  of  the  facial  nucleus  (higher up) in having
uniformly shaped cells scattered all around it.   These cells, which
contribute  to the  formation  of a  network  of  gray  fibres, are
traversed by arciform fibres, which can be traced into the bundles
of the external auditory nucleus (Figs. 50, 51, 52—y).
                                Fig. 52.
                  Stained with Potassium and Gold Chloride.

     Transparent Section through the Medulla Oblongata of New-born Infant.
    12  Hypoglossal nuclei.   IO. Vagus nuclei.  A., A. External auditory nuclei with
auditory roots  CR., CR. Restiform body. fp. Posterior column v. Trigeminal root
g.  Gelatinous substance.   fl.  Lateral columns.   L.  External bundles of lateral
columns, on the  inner side of which  deep  arciform fibres of the restiform body are
situated.   oe. External accessory olive.   o. Olive.   oi.  Internal accessory o ive
XII  Twelfth nerve.  P. Pyramid,  fa.  Funiculus anterior.  CH.  (left).  Roots ot
vagus,   n.a. Region of the anterior nucleus of  the vagus.   Xr.  Recurrent roots of
vaaus.  X. Roots of tenth nerve : a fibrae arcuatae from the vagus nuclei ; 0 from
the  joint ascending root ;  y   from the acoustic nuclei ;  8  from the  posterior
column ; and e from the restiform body.

CROSS-SECTION OF THE OBLONGATA  AND  ITS TRANSITION INTO THE

                             SPINAL  CORD.

    On the outer side of the  median-anterior columns  and  the

pyramidal area of  the oblongata, the  lateral  columns extend as

far as  the cross-section  of the  trigeminal  nerve.  They are  dis-

tinguished from the very dense and coarse fasciculi of the anterior 
126                      Psychiatry.
columns by the lesser density and the lesser thickness of their fibres.
The lateral column fills out  the segment of the cross-section of
the oblongata between the roots of the hypoglossal and trigeminal
nerves.   The  funiculus lateralis encloses the lower olive, and is
joined to  it by horizontal  bundles (Fig. 57, o).   Immediately be-
hind the lateral column lies the trigeminal root, and behind  this,
to the outside, lies the scythe-shaped section of the corp. restiforme
(Figs. 45 and 50, R., Cr.), and in a median direction from the resti-
form body lies the external auditory nucleus.   This nucleus, under
the name of  Clarke's nucleus, forms the lateral boundary of the
gray substance.  The groove-shaped  section  of  the  trigeminal
root surrounds a gray column, the substantia gelatinosa, which, as
in tne spinal cord, forms an indentation or wave visible  on distinct
preparations.  This formation is traversed by tranverse  arciform
fibres, which issue in part from the nerve-nuclei and in part from
the corpus restiforme.
    1. The most posterior (dorsal) of the fibrae arcuatae connect the
nuclei of the vagus with the raphe (Figs. 50, 51, 52—a), and, in so
doing, separate the hypoglossal root  from its nucleus.
   2. Then there follow fibres which have been unravelled from
the ascending root of the ninth and tenth nerves  (/?).
    3. Fibrae arcuatae arise from bundles of the eighth nerve, which
extend far down  into the oblongata, and do not disappear until
just above the closure of the central  canal (y).
   The region of the arciform  bundles issuing from the nerve
origins is distinctly  separate from the more anteriorly situated
systems of fibrae  arcuatae ;  nor do the  former  traverse either the
olives or inner olivary bodies.
   The corpus restiforme soon forfeits a number of its bundles,
which  go  to  the surface  of the oblongata, there forming  the
stratum zonale, covering and invading  the olivary body.   Inspec-
tion of  the surface  of  the oblongata  reveals the fact  that  the
stratum zonale does not lie  altogether in transverse  planes, but
that it descends  obliquely.  These  bundles  are situated  on the
outer side upon  the trigeminal root.   Deeper layers from the
corpus restiforme send  coarse bundles through the section of the
fifth nerve, but invariably to the outside of  the substantia  gela-
tinosa.  Superficial bundles of the restiform body, which lie upon
the fifth  nerve, often continue the stratum  zonale'iar enough to
cover the pyramids.   If such bundles unite on the cross-section of
the pyramids  with islands of gray substance, then we consider 
Origin of Spinal Cord.
127
them bundles of  the pons which cross the corpus restiforme.   In
the  lowest  strata of the  pons,  we find bundles  taking such a
course, into the corpus restiforme and not into the brachium pontis,
the two types of bundles separating distinctly in the cerebellum.
On the  other hand, the stratum zonale allows an external layer of
the funiculus lateralis to touch the surface, surrounding the latter
on  its inner aspect  (Fig. 52,  left L.).  Such bundles  protruding
behind the olivary bodies give rise to an external limiting fasiculus
and in the same way longitudinal bundles on the inner side of the
olivary  bodies may be exposed and form the inner limiting fasicu-
lus; (Fig. 15), owing to a deeper course of the stratum zonale.  As
a rule the pyramids remain  free.   The  superficial layer of  the
corpus restiforme, the stratum  zonale, not only covers, but actually
crosses  the olivary body of the same side.   The deep layers of the
restiform body take the same course through the olives and inner
accessory olives (Figs. 50, 51,  52—s).
    The bundles of the restiform body cross in a transverse direc-
tion through the raphe from one side to the other, emerging from
the hilus of one olive and passing into the hilus  of the other.
These fibres cannot represent  a true commissure of the olives, for
the fibres have dissimilar (ungleichnamige)  endings.  From  the
opposite  olivary body  restiform bundles  pass  into a dense, co-
lumnar1 mass of  fibrae arcuatae, which are found to the inner side
of the gelatinous substance, and instead of  entering the corpus
restiforme pass into the posterior column.
    On sections, which  pass between the point of emergence of
the ninth nerve and the region of the nucleus of the tenth nerve,
a new formation is seen to edge in between the  corpus restiforme
and the region of the auditory root.   This formation is the funicu-
lus posterior of the  oblongata, which passes into the posterior
columns of  the spinal column, through the funiculi graciles and
cuneati  (Figs. 50, 51, 52—Hst.,  Pst.,  fp.).  The funiculus  pos-
terior has a net-like  structure, the fibres of that net enclosing
clusters of middle-sized ganglion cells.  This formation stands in
striking contrast to the external auditory nucleus, where  distinct
sections  of bundles  are imbedded  in  a floor of gray substance.
In the one instance we find bundles imbedded in gray substance ;
in the other,  gray  substance  in  a network  of bundles.   These
posterior  columns gather fibres from  that set  of  fibrae arcuatae
(Figs. 50, 51, 52—6) which are situated between those derived from
This refers to the appearance on cross-sections. 
128
Psychiatry.
Clarke's auditory nucleus and  those from  the restiform  body.
The fibrae arcuatae in question also pass through the olivary body,
and, as is worth mentioning, through the external secondary olive
also.
    In the arciform course of those bundles which connect the pos-
terior columns and the corpus restiforme, no cells are seen scattered
in between these  fibres, from which the posterior columns might be
derived.  It would be difficult, were it  not for a single circum-
stance, to decipher the origin of the bundles which go to make up
the posterior column  ; this fact is, that in proportion as the corpus
restiforme diminishes  in volume by yielding up fibrae arcuatae (Figs.
50, 51, 52—zone  e), so the  posterior columns develop by the ad-
dition of the posterior fibrce arcuata? (Figs. 50, 51,  52—zone S).
There can be but little  doubt,  therefore, that the corpora resti-
formia,  after passing  the olivary bodies,  pass into the  posterior
columns of the opposite side.   In the olivary bodies the restiform
bodies end,  and the posterior columns begin.   It is known of  the
olive (Deiters), that very coarse fibres of the corpus restiforme pass
through it, and that  very delicate bundles are distributed within
it.   The coarse  restiform bundles simply pass through the  oli-
vary body  of the same  side, but terminate in the  olive  of  the
opposite side.  Proof of  this may be found in the fact that if  one
half of the cerebellum and the restiform body atrophy, the olivary
body of the opposite  side will also degenerate.
    The posterior columns once formed, the transition  from  the
cross-section of the oblongata to  that of  the  medulla spinalis is
easily effected ; for the floor of the IV. ventricle changes into the
gray substance surrounding the  central canal.   At such levels at
which the corpus restiforme lies next to  the  beginnings of  the
posterior column, it  is situated to  the outer  side of the latter.
The posterior column forms  on its  inner side (Figs. 50-52),  the
substance of the restiform body diminishing on  the outer side, and
the posterior columns increasing on the inner side.  In conse-
quence of this mode of growth the region of the corpus restiforme
and the funiculus posterior is pushed toward the median line, in
the direction  in which new growth takes place.   The  result of
this  is that in the adjoining halves  of the gray floor  upon which
the posterior column  encroaches after the disappearance  of  the
acoustic nucleus,  the  nuclei of the tenth  nerve occupy a more
median  position.   The hypoglossal nucleus, the representative of
the anterior spinal-cord nucleus, does not change its  position, for
the posterior  column turns inward  back  of this  nucleus.   Cer- 
Origin of Spvial  Cord.
129
tain roots of the  tenth nerve  intersect the gelatinous substance
in the  trigeminal  nucleus, just as  its continuation  in the spinal
cord is intersected by posterior roots.  The nucleus and roots  of
the vagus are prototypes of the posterior horn of the spinal cord.
The substantia gelatinosa represents  the caput of  the  posterior
horn;  the vagus roots are its cervix, and the vagus nucleus, which
is connected with  the anterior horn (the hypoglossal nucleus) and
turns toward the cervix the apex of a triangle, corresponds to the
trigonum ccrvicale  of Goll, the triangular section of the union of the
     Stained with Potassium and Gold Chloride.
Cross-Section through the Oblongata of the New-born.
   c. Central canal.   P. Pyramids.  X. Decussating bundles,  o, oi. Region  of
olives,  g. Gelatinous substance,  v. Trigeminal bundles,  c. p. Caput of  posterior
horn.  f.  b. Fibrae arcuatae.  c. a. Anterior horn.  n. Nucleus of fasciculus cuneatus.
fr. Fasciculus cuneatus.   f. gr. Fasciculus gracilis.
   N. B.— The commissure back of c. does not exist in reality.
posterior horn with the entire gray nucleus.  This posterior horn
of the  oblongata  lies, as it is, between the lateral and posterior
columns, and there  is a  difference only in its  being covered by
trigeminal roots, and in  the angle formed by the two posterior
horns.  The roots of  the  vagus, if prolonged, would  intersect
behind  the oblongata,  while the posterior roots of the spinal cord
would  intersect anteriorly.  The former diverge  anteriorly, and
the latter posteriorly.  The nucleus of the tenth nerve turns
inward, approaches  the  median  line,  unites with its  fellow of 
130
Psychiatry.
the opposite side,  and  thus closes the canalis centralis.   The
fossa rhomboidea has disappeared.  The posterior columns crowd
toward  the median line, behind the  united nuclei of the tenth
nerve, leaving naught but the posterior fissure between them.   But
the entire posterior  horn has  followed the  inward twisting of
the vagus nuclei, so that  the  posterior  horns, from which the I.
and 2. cervical  nerve-roots below the vagus  arise,  are  no longer
convergent posteriorly, but are juxtaposed at an angle of i8o° ; as
                                   soon as the  fibrae  arcuatae
                                   disappear, the posterior horns
                                   with the  nerve-nuclei in the
                                   funiculi graciles  and cuneati
                                   are  separated  less  and  less
                                   until they approach  one an-
                                   other  and  converge  anteri-
                                   orly.  In consequence of the
                                   disappearance  of the  fibrae
                                   arcuatae  and  of the  inner
                                   olive,  the anterior columns
                                   become  more  compact; and
                                   this  is  true also of the lateral
                                   columns,  which,  instead  of
                                   presenting a  convexity, ex-
                                   hibit, as soon  as the olivary
                                   bodies disappear, a flattened
                                   surface behind the pyramidal
                                   tracts (Fig. 53).  Behind the
                                   lateral column, the trigeminal
                                   fibres  which  are no  longer
                                   covered by fibrae arcuatae are
                                   replaced by the convex region
                                   of the substantia Rolandi (Fig.
                                   54,  V.,  SR.).   Back of this
the gray  substance scattered  in among the posterior columns,
gives rise to two well-defined convex formations—the funiculus
cuneatus, and funiculus gracilis (Fig. 53,  fr., f. gr.), the latter lying
immediately adjoining the posterior fissure.  Before the total disap-
pearance of the inner accessory olive, the lower boundary of which
Stilling thought coincided with the lower limit of the hypoglos-
sal roots,  the posterior column receives additions from a decussa-
tion of fibres  between the anterior columns ;  these fibres  are
             Fig. 54.
        Carmine Preparation.
 Decussation of the Pyramids in the Adult.
   Hst.  Funiculus posterior. C. Central
Canal.  V, V, SR. Caput cornu posterioris,
substantia  Rolandi, on the  left side with
vestiges of the  ascending  trigeminal root.
LS. Lateral column. VS. Anterior column.
P. P. Pyramids. 
Cross-Section of Spinal Cord.             131
stouter than  those  of  the fibrae arcuatae which decussate higher
up.  Clarke and I thought they were  derived from the external
bundles of  the pyramidal tracts.  There is every reason to doubt
the correctness of this view, for the inner accessory olive adjoins
those bundles which take a  transverse direction from the outside
into the decussation.  If they pass through this ganglion it would
be  natural  to suppose that  they were  derived from  the corpus
restiforme.   This view would not be  contradicted by an inspec-
tion of gold preparations (53, oi., X., f. gr.).   Assuming this to be
the case, they would be  distinguished from the rest of the forma-
tion of the posterior column in this, that the decussation would not
consist of restiform bundles decussating at the hither side of the
enclosed olive, but that it would consist of  fibres which enter the
funiculus gracilis, decussating at the further side of the enclosed,
inner secondary olive.
    The entire pyramidal tracts  are lost from the anterior fissure on
through the great decussation of the pyramids ; they crowd the an-
terior columns far from the raphe which they fill out and expand ;
they separate the anterior horns from the gray substance, but how-
ever much they may push the posterior horns  backward, these
pyramidal  tracts still pass entirely and continuously into an area
of  the lateral column which lies next to the posterior horn, but
does not extend to the external  surface of the most posterior
part  of the lateral column.  The  position which  the  pyramidal
bundles occupy  after decussation  as longitudinal fibres of the
lateral columns,  passing gradually  into  the anterior roots, they
retain throughout  the entire length of the spinal cord (Fig. 54,
P.  P.).
                CROSS-SECTION OF THE  SPINAL CORD.1
    We remarked above that the cross-section  of the brain-trunk,
at the lowest division of the mesencephalon exhibits three distinct
masses of fibres, bearing downwards, and superimposed one upon
the other.   These were the tegmentum, the stratum intermedium,
and  the  pes pedunculi.   The  cross-section  thus  constituted  re-
    1 Prof. Meynert's interpretation of the cerebral origin of the spinal-cord tracts dif-
fers widely from that given by other authors.   The reader who is especially interested
.in this part of the subject is referred to the following publications :  Flechsig : Leit-
ungsbahnen ini Gehini u. Ruckenmarke ; Leipsic, 1876. p. 263, etc.  Flechsig: Plan
des Mensdilichen Gehirnes; Leipsic, 1S83.  Alby :  Schema des Faserverlaufes im
Menschlichen  Gehirn und Ruckenmark ; Bern, 18S3. Roller: Die Schleife. Arch, f
mikroskopische Anatomie ; Bd.  xix , p. 240, 138 r. Wernicke:  Lehrbuch der Grhim-
krankheilen; Kassel, 1881. Starr: Sensory Tract, JournalofNervous and Mental Dis-
ease, July, 1SS4,  Spiszka: On the Lemniscus, etc., New York Med. Record, 1884. Edin-
ger: Zekn Vorlesungen uber den Bau der nervbsen Lentratorgane ; Leipsic, 1885.—S. 
132
Psychiatry.
ceived an  increase in the oblongata, in the  form of an addition
from  the cerebellum, which was joined to the other behind the
continuation of  the tegmentum.  At  this  point  there were four
layers:   corpus  restiforme, or  funiculus posterior;  tegmentum,
stratum  intermedium, and pyramidal  tracts.
    The  formation of the spinal cord is the result of  the union
of bundles coming from the different centres of the cerebrum and
cerebellum.   Whether their wealth of fibres.increases or not, there
Transparent Sagittal Section through the Brain of the Monkey.  (More Lateral than
                            Figs. 56 and 57.)
    Fr. Frontal end. Occ. Occipital extremity, c.d. Corpus callosum. n.l. Lenticular
nucleus.   nc. Caudate nucleus.  Lp.f.  (o) Lamina  perforata anterior,  ged.dept.
pelt. Region of the pedunculus septi pellucidi.  II. Optic tract., above it the optic
commissure,  ci. Internal capsule.   Th.  Optic thalamus.  L.lf.  Discus lentiformis.
The dark (shaded) bundles, forming an < around its anterior end, constitute the radia-
tion of the posterior longitudinal fasciculus.  Between this formation and the thala-
mus is the  radiation of the  nucleus  ruber.  Cp. Posterior  commissure.   Q.  Corpus
quadrigeminum  in which the brachium corp. big. superius (bearing downward and back-
ward), and the fillets (Lms 2, Lms 3, bearing downward and forward) are seen.  The
lowest white bundle is the cerebellar  lemniscus (Lms  3)  from the valvula cerebri.
Behind Lms 3, the trigeminal root. ss. Soemmering's substance with its medullary sub-
stance.   P.  Pes pedunculi.  v.  Pons Varolii.  C.tr.  Oblongata (corp. trapez.).  R.
Corp. restiforme.  Cbl. Cerebellum,  nd. Dentate nucleus of cerebellum.

is no reason  to suppose that these bundles would occupy any other

position  relatively  to each other  than  they hold in  the crus

cerebri and  in the  oblongata.   Inasmuch  as  continuity of  the

bundles  can  be studied best on sagittal sections, Figs. 55-57  are

added  as supplementary to the previous descriptions of the  brain. 
                Cross-Section of Spinal Cord.            133

   The tegmentum is composed of four distinct sets of fasciculi
of origin (Ursprungsbiindeln).
   1. The fasciculus longitudinalis posterior does not seem to end
altogether at the lower margin  of the pons and in the oblongata.
It might be traced  to those  posterior bundles of the anterior
columns (on the spinal-cord section) which are situated in part
immediately in front of the gray  spinal  commissure—the pro-
longation of the gray floor  of the brain,—and in part are crossed
by the white bundles of the anterior commissure (Fig.  58).  The
radiation of the posterior longitudinal bundle from the cerebral
cortex contributes a  small number of fibres to the cross-section of
the crus cerebri, and there is no doubt that in the brain-trunk its
bundles are interrupted by masses of gray substance, each cerebral
nerve-nucleus constituting an internodium.  And yet the fasciculus
longitudinalis posterior forms the most direct connection between
the  gray substance of the spinal cord and  the cerebral  cortex,
for the gray internodia high up in the brain, such as the ganglion
optician basalc, are equivalent to the central gray substance of the
spinal cord (Figs. 18, 21, 31, 37, 40-44, 55>and S6-  Cf. p. 96, etc.).
    2. The bundles of the anterior pedicle of the thalamus, which,
as laminae medullares, emerge like the rays of a fan from the thala-
 mus,and can be traced in the tegmentum to bundles situated to
the  outer side of the red  nucleus  (Figs. 29, 34-36, 38, 55.  Cf.
 pp.  89, 91, etc.).
    3. The fasciculus retrofiexus might be considered the continu-
 ation of that  portion of the stratum zonale which participates in
 the  formation of the ansa peduncularis ;  it  passes through the
 peduncle of the pineal gland into the posterior commissure.
    An ependymal connection with the posterior surface of the fornix might lead one
 to believe that there is a connection of the pineal peduncle with the posterior surface
 of the fornix.
    These bundles twist about in such a way that in the tegmentum
 they constitute the innermost  anterior bundles, and  in  contrast
 to the  posterior long, bundles participate in the formation of the
 anterior column  of  the tegmentum  (Figs. 34, 35,  38, and a frag-
 ment in Fig. 56.  Cf. p. 90).
    4.  The bundles  from  the  posterior commissure, which enter
 the thalamus  along its inner  margin, after  passing through the
 ansa peduncularis,  and  constitute  its stilus anterior.   These
 bundles and  the fasciculus retrofiexus represent the  crossed
 thalamic origin of the spinal cord (Figs. 17, 18, 31, and 57).  The 
134
Psychiatry.
former bundles are well exhibited on Fig. 57, where they are seen
entering the tegmentum ; according to Fig. 34 they lie behind the
origin of the  fasciculus retrofiexus, and by comparison with the
brains of carnivora seem to me to constitute an opaquely bounded
column  lying in front of the gray substance and  to the outside
of  the  posterior longitudinal bundle  (in  the  mesencephalon).
This column is intersected by the fasciculi marginalcs aquaeducti
Sylvii.   On  the supposition that it descends directly to the spinal
cord we should  have to look for this formation in the  funiculus
lateralis, next to the external margin of the anterior horn (Fig.
                               Fig. 56.
        Transparent Longitudinal Section through the Brain of a Monkey.
    Fr. Frontal end.  OCC. Occipital end.  Rd. Cortex cerebri.   M. Medullary
substance of the fore-brain.  Nc. Caudate nucleus.  L. Lenticular nucleus. C. Anterior
commissura.  N.  Globus pallidus.  A. Amygdala.  II.  Optic tract.  CL  Internal
capsule.  Th. Thalamus.  Br.  Brachium corporis quadrigemini.  Lb. Discus lenti-
formis (by  mistake of the engraver united  to the stratum intermedium.  1 he dark-
pointed triangular mass in  front  of it is the radiation of the posterior longitudinal
fasciculus.  Underneath Br. The radiation of the nucleus ruber). L, L, , LT]T.  Lemnis-
cus of the superior and inferior corpus bigeminum, and of the valvula cerebelli.  P.P.
Pes pedunculi. P. Pons Varolii.  Rh. Corpus rhomboideum. O. Inferior olive.  Cbl.
Cerebellum.  Pr.  Processus cerebelli ad  cerebrum.  R. Corpus restiforme.  Fp.
Funiculus posterior.

    5. The  quadrigeminal  origin  of the  spinal cord  is embodied

in the lemniscus, which  can be pursued quite to  the medulla

spinalis on Figs. 55 and 56;  particularly in the former.   The divi-

sions of the lemniscus constitute  the  most  anterior  layer of the

funiculus lateralis, are  crossed in  or  below the  pons  (according

to the  structure  of the animal's brain) by the  transverse bundles 
Origin of Spinal Cord                 135
of the corpus rhomboideum, and in the oblongata enclose the lower
olive, in  the cells  of which possibly some of their bundles termi-
nate, unless they should  alter  their  position  and pass to the
back of the olivary  bodies.  In the spinal cord the layer of the
lemniscus would correspond to the external stratum of the lateral
column (Fig.  58), and possibly to the most anterior layer of the
anterior columns.  The analogue of the quadrigeminal layer of the
lemniscus would, in  the spinal cord, not extend as far as the caput
of the posterior horn (Figs. 17, 22, 40-45, 55, and 56.  Cf. pp. 34,
102, 103 .
                               Fig. 57-
Sagittal Section through the Brain of a Monkey.   The Most Median Section of
                           Figs.  55, 56, or 57.
    Ca. Anterior commissure.  II.  Optic tract.   Th. Thalamus.   st. i. Internal
pedicle of thalamus covering the ascending  crus  fornicis (white).   cp. Posterior
commissure.   III.  Third nerve.  Between cp. and III. the tegmentum,  on the back
of which lie the roots of the fourth nerve.  Pr. Decussation of the superior cerebellar
peduncles.  Between pons and third nerve innermost bundles of the crus, which run
from the pes pedunculi into the posterior division of the pons, and are cut off on their
course toward the  median  line.  L. Stratum lemnisci.  Rh. Fossa  rhomboidea,  in
front of it the roots of the sixth nerve.  12.  Hypoglossal roots, v. Pons Varolii; be-
hind the  transverse basilar bundles, the pyramidal tract,   al.  Behind the pyramidal
tract we find the lemniscus passing through the olivary body, for lower down the sec-
tion inclines strongly to the outside ; this lemniscal layer was traversed  above by the
roots of the sixth nerve and the transverse fibres of the corpus rhomboideum.   Cbl.
Cerebellum with the valvula ad. corp. quadrigemina.   Fg.  Funiculus gracilis.

    The gap left in the spinal cord by the quadrigeminal lemniscal

layer is filled  in  by  the cerebellar or lower lemniscus, which is

derived from the vermis superior of the cerebellum, passes through 
136
Psychiatry.
the valvula cerebri, and joins the quadrigeminal lemniscus.  From
the manner in which the lemniscal layer advances, we can under-
stand why this last addition should  represent the most posterior
(or, in the pons, the most external) bundles of the lemniscus;  for
in the cross-section of the lemniscus the quadrigeminal fibres are
so arranged,  that those  originating  highest are  pushed farthest
toward the median line, and the lower bundles join the lemniscus
externally in the order of their descent.   The lowest addition to
the lemniscus would, therefore, form its most external  bundle.
But in the spinal cord the lemniscus cannot spread as readily
in a transverse direction as it could in the crus cerebri and in  the
pons.  Its bundles will necessarily lie behind one  another, and
the outermost bundle will become the hindermost (Fig. 58).
    Genetically, this portion of the external layer of the  lateral
column would have a distinct anterior  boundary, for the spinal-
cord mantle  develops around the anterior and posterior horn in
the form of  an antero-lateral and a postero-.lateral column.  The
latter adjoins the posterior horn.  The hindermost lemniscal layer
undoubtedly forms in the spinal cord that portion of the postero-
lateral column  which constitutes the anterior boundary  of  the
caput cornu posterioris (Figs. 17,  55, and 56.   Cf. p. 34).
    6. The stratum intermedium is the representative of the  nu-
cleus lenticularis in  the spinal cord, though some  of the crural
bundles  of  the  latter may have  entered  the pyramidal tracts.
On sections through the crus cerebri the strata intermedia lay to
the outside  of the outermost bundles of the pes pedunculi, and
were confluent in the median line.  The stratum intermedium is
composed of the ansa lenticularis, the innermost bundles of the pes
pedunculi, and of other fibres of origin of the lenticular nucleus,
which, after  interweaving with the pes pedunculi, or the capsula
interna, respectively, enter the lateral portions of  Soemmering's
substance.  In the oblongata, this stratum lies in the same trans-
verse position immediately behind the pyramids.   Upon  diminu-
tion  in  the size  of  the  stratum  intermedium,  followed  a
diminution of the angle between the two continued  halves of this
stratum  (originally amounting  to  180°), for these two  halves,
forming  the  posterior boundary of diminished pyramidal tracts,
had to  approach each other more closely.  As  the decussation
increases, the angle grows  more acute,  and as soon as the  last
traces of the pyramidal tracts have disappeared, the  two halves of
the stratum  intermedium lie immediately adjoining the anterior 
 
 
Cross-Section of Spinal Cord.            137
fissure of the spinal cord, there forming the innermost bundles of
the anterior columns (Figs. 22, 23, 31, 34, 36, 37, and  58.   Cf.
pp. 45, 51,  54, 55, 80, 106, 107).
    7. The  pes pedunculi has a  twofold origin: as the fasciculus
of Arnold of  the internal capsule from the cortex bf the fronto-
parietal lobe, and as the fasciculus of Gratiolet,  from the  occipital
and temporal lobes. Its cross-section area  in the mesencephalon is
so constituted  that its innermost bundles belong to  the stratum
intermedium (ansa lenticularis), that  its  outermost  bundles  are
those  described by Gratiolet  and myself, and that  the largest
mass between  the parts  referred to contains the remaining
pyramidal  bundles, and the medipeduncular1 bundles of the crus
cerebri.  In point  of  calibre, the lenticular portion is the small-
est, the bundles of Gratiolet  of far greater dimensions, while
the last-named of  the  three divisions is the most powerful of  all.
In the spinal cord,  the pyramida1 bundles are lodged  to the front
of  the posterior horn, but  do not extend either to the outer sur-
face of the lateral columns corresponding to the fillet, or to  the
anterior portions of the posterior horn (Stilling, Flechsig).
    That portion of the spinal-cord  section  which  immediately
surrounds  the  gray  substance  from  the anterior horn to  the
caput of the posterior horn, contains all the thalamic  fibres of  the
spinal cord ; though the origin  of some of these bundles  may still
be hypothetical. (Figs. 15,  17,22,23, 30, 31, 33, 34, 36, 37, 40,41 ;
regarding bundles of Gratiolet,  Fig. 33.  Cf. pp. 27, 50, 81, 84, 85.)
    8. The outermost  area  of  the brain-trunk,  the  corpus resti-
forme, is added to the  oblongata from  the  cerebellum; it is
derived from the laminated medullary substance immediately sur-
rounding the nucleus  dentatus, and passes through the stratum
zonale, and through the mediation of the two most anterior sets of
fibrce arcuatce  into the posterior column. The  term "funiculus
cuneatus of Goll"  may easily lead  to confusion in  spinal-cord
terminology.  This strand, which takes on a bright red color when
stained with carmine,  and  in  the  foetal spinal cord  is distinctly
separate from  the  lateral portions of the funiculi cuneati  in  the
oblongata, is the spinal continuation of the funiculus gracilis and
not of the  funiculus cuneatus.
    That the bundles   of Gratiolet in  the pyramidal tracts may
participate in the formation of the posterior columns, or their inner
portion at  least, is  not at all improbable (Figs. 15, 17, 22, 23,  45-
47, 52, and 53, Cf.  pp.  28, 36, 119, 126).
In Wilder's sense. 
ANATOMICAL   COROLLARIES  AND   PHYSI-
   OLOGY  OF  CEREBRAL ARCHITECTURE.

   In  the preceding  section  of  this work we  discussed  the
structure of the brain.  We have  now to  consider a number of
anatomical corollaries which  will explain certain functions of
this mechanism upon which physiological experiments have shed
no light hitherto.   Our understanding of those functions will be
advanced, too, by close attention to the pathological anatomy of
the organ under consideration.
   A mechanism may operate  before  us without our recognizing
the exact relation between its function and its architecture.  But,
on the other hand,  if  we are acquainted with  the principles upon
which  this mechanism operates, we may infer its  function  from
its structure, regarding the former as the natural outcome of the
latter.
   This method of reasoning would be applicable to the brain, even
though the principles  involved in  its  activity were  entirely un-
known.  Moreover, matters are simplified very much in the case of
the brain, for, without committing serious error, we may regard it as
made up of a large  number of entirely  similar structural elements.
   In order to establish anatomical corollaries, wre need postulate
but a single principle, abundantly proven by physiological experi-
ments.  This  is Bell's law of  the conduction  of nerve-force in a
centripetal  direction through the posterior, and  in a centrifugal
direction through the anterior,  spinal roots.    We need not, how-
ever, accept Joh. Miiller's opinion, that, at the very outset, differ-
ent parts of  the brain display different functional energies.  A
single functional energy only, though as inexplicable as all physi-
ological forces, is inherent in the brain-cell, and that is Sensitive-
ness.  Actual  sensation is  developed by the evolution of equally
unknown  external  forces, which  we  must suppose  differ very
materially  from  one another.
   These differences imply a difference in anatomical structures,
not of  the  brain, but of the terminal organs of peripheral nerves.
                              T38 
            Relation of Cortex to  Outer  World.         139

This is well illustrated in the case of the anterior roots, which are
motor in function, simply because the terminal organs of nerves
derived from the anterior roots are connected with muscles.  The
latter alone are motor elements.   Nerves and nerve-cells possess
no  motor power.   Indeed, there  is nothing more certain about
the functions of the cerebral  organism than that the centripetal
sensory nerves  are  the keys which wind  up the mechanism con-
nected with the muscles, and excite the latter to action.
    A varying  functional energy  of  brain-cells, according to the
special organ of sense with which they may be connected, is quite
indemonstrable, since we are acquainted with  the physiological
conditions favorable  to  the  action  of external forces, and  can
prove easily enough that it devolves upon the terminal organs of
the nerves to meet these conditions.   Even if the auditory nerves
possessed a specific visual energy, the media between the auditory
nerve and  the waves  of  light would  be totally unfit to transmit
visual rays.
    Specific energies therefore depend altogether upon the peculi-
arities of  the  end-organs,  and  sensitiveness is  the  only  specific
property of brain-cells.
    Within the fore-brain sensitiveness is converted into actual
sensation.
    The relation of the fore-brain to the other parts of the cerebral
mechanism is easily understood.   To this end we  may recall the
structure of the retina, which constitutes a hollow  into which the
visual rays  from  the external world are, as it were, entrapped.
And, in the same way, we may look upon each half of the cortex of
the fore-brain as a concave organ, duplicated in parts, enveloping
all  the nerve tracts, which conduct to it the  impressions from the
outer world. In this organ these impressions are converted into the
phenomena of  sensation.   In assimilating totally unknown physi-
cal impulses, the  cerebral  cortex,  a complicated  protoplasmic
structure,  resembles  the protoplasm  of the  primitive amoeba,
which can  transform itself  into a  hollow  mass,  and  can  thus
encircle  any hody which it  wishes to  assimilate.  Just as the
mollusca possess tentacles which  they protrude toward the outer
world, and claws by means of which they take possession of their
booty, so  this  complicated protoplasmic organism, the prosen-
cephalic cortex, possesses  centripetally-conducting processes,—
the sensory fibres of the nervous system—which we may con-
sider  its tentacles, and motor fibres, which are its  claws.  The 
140
Psychiatry.
remainder of the body, with its sensitive surfaces, its muscles, and
the skeleton to which  these  muscles are attached, serves to sus-
tain these tentacles and claws, which enable the fore-brain to re-
ceive  the images of the external world, and to react upon the
latter.   Comparing the disposition  of the  gray substance in the
spinal cord with its arrangement in the cortex, we observe that the
gray substance  in  the spinal cord is very much crowded  by the
aggregation  of  medullary  strands on its periphery.   Nerve-ele-
ments  corresponding  to  tentacles  and  claws  are thus  closely
united, and  the functional  result of  this union is exhibited in the
reflexes which the spinai  cord necessarily develops, as soon as
those higher cerebral  structures which  have an inhibiting influ-
ence upon its vital activities have  been removed.   In the fore-
brain, on the other hand, the gray substance is not lodged  in the
white, but the white substance in the gray, and  the former pushes
the cortex asunder.  Knowing the difficulties of nerve-conduction
through the gray network of fibres, we may infer that this en-
larged  surface  will be able to  perform a number of totally inde-
pendent functions;  that a sensory perception, for instance, need not
give rise immediately to a  motor act.  Every spinal-cord segment
embraces the  whole  of  the gray  substance,  whereas sections
through the cortex contain but  a  small portion of the cortical
gray.   This  distribution  of  gray  substance will  naturally  pre-
vent the entire cortex from acting to one  single end, while  it
favors the isolated action of various cortical regions.   Irradiation
of functions is facilitated in the gray substance of the spinal cord,
and rendered difficult in that of the  cortex.   We learned, further-
more, that  the  cortical structure was not the same throughout;
that the arrangement of  the  cortical elements varied  in different
divisions of the cortex.  Purely morphological data arid a single
pathological anatomical fact will enable us to determine which re-
gions of the cortex, in the probable division  of labor, take upon
themselves centrifugal functions in the sense implied in Bell's law.
The pathological fact referred to is the hemiplegia resulting from
destruction  of the  prosencephalic ganglia,  and particularly from
destruction of. the nucleus  lenticularis.   These ganglionic  masses
divide  into  a club-shaped  body (nucleus caudatus), and a  wedge-
shaped body (nucleus lenticularis), both presenting their broadest
surfaces anteriorly (cephalad).  Upon the number of cortical cells,
depends the number of radiating fibres which the ganglia receive ;
accordingly the  anterior  portions  of the  prosencephalic ganglion 
Proof of Cortical Localization.            141
must  contain by far the largest number of cells for the reception
of these radiating fibres.  We may therefore establish this morpho-
logical corollary, that the cells of these ganglia will be able to re-
ceive  more fibres from the anterior cortical  regions than from the
posterior ventral regions of the hemispheres, for  these ganglionic
masses, tapering as they do toward this latter region, will naturally
have a lesser number of cells to put at the disposal of fibres coming
from that direction.  Besides, Gratiolet and I observed that the oc-
cipital and temporal cortex received fibres from those ganglia with
which the optic tract is connected.  And into these latter regions of
the cortex those bundles of the internal capsule enter, which, when
implicated in a lesion, give rise to hemianaesthesia (Tiirck).  It
was well known also that the anterior commissure, which was sup-
posed to be an  olfactory chiasm, was not connected with the
cortex of the frontal lobe, but according  to Arnold with those of
the temporal lobe ; Burdach and myself insisting on a further con-
nection with the cortex of the occipital lobe.  This separation of
sensory and motor areas in the cortex was later on substantiated
by the results of physiological experiments.
    Before discussing these physiological experiments, I wish to
call attention to three anatomical  facts which render a functional
differentiation  of  the various cortical regions highly probable.
The first of these facts  is taken from comparative anatomy, and
refers to the enormous difference in development of the olfactory
lobe in different animals.  Animals that  are accustomed  to run
their  noses close to the  ground, and to  obtain  their food  by
following the scents they perceive, are characterized by a highly
developed olfactory lobe, as is shown in Figs. 7 and 10.   In  man,
whose erect posture has lessened  such sense-impressions, as well
as in  the monkey and in all climbing animals, the olfactory lobe
has deteriorated  very much.   Among water mammals, the sea-
lion, which spends part  of its life on land, has an olfactory lobe
about equal  in dimensions to that  of man, while cetaceans have
no olfactory lobe at all.
    The second fact refers to the difference in the relation between
the median and the convex surfaces of the cortex, in animals with
strongly developed olfactory lobe, and in  man.  In the latter, the
convolutions of the convex surface everywhere overtop the gyrus
fornicatus ; whereas, in the former category of animals, this  same
gyrus, which is connected with the olfactory lobe,  is  enormously
developed, forming, together with the external olfactory convolu- 
142                      Psychiatry.
tion, the gyrus uncinatus of the convexity which continues the
formation of  the cornu ammonis to the  middle of the  corpus
callosum ; while in man this formation but barely grazes the pos-
terior surface of the corp. callosum.
   Thirdly.  Among the convoluted regions of the convexity of
the human brain, the  walls of the Sylvian fissure are most  highly
developed.  This includes its floor, the island  of Reil,  as well as
the operculum covering the island from above, and the first tem-
poral convolution covering it from below, and also the transitional
convolution, together with the posterior  margin of the  orbital
surface closing, in upon the anterior border of the island.  In
keeping with  these peculiarities of structure, the human brain
exhibits  the most  extensive claustrum.   But I have shown that
the disturbances of psychical  speech,  which  are classed  under
aphasia and its allied  conditions, depend upon lesions in the claus-
trum—in general  terms, upon  lesions in the walls of the Sylvian
fossa.  Man as far excels in the development of these psychical
regions of speech, and in the number of convolutions  belonging
to these  regions, as animals with highly developed olfactory lobes
excel in  regard to the size  of  these lobes.   From this we may
unquestionably infer that evolution of certain psychical functions
will go hand in hand with a proportionate development of certain
regions of the cortex.
   We may as well add at once that there are  quantitative dif-
ferences in the brain-trunk, both in man and in animals, dependent
upon quantitative variations in the different parts of the fore-
brain.  An  inspection  of  the basilar surface of the cerebrum
confirms this  view.   The ideas suggested  by such considerations
as these were referred to on page 82, where it was shown  that, in
keeping  with the  quantitative development of the  fore-brain,
those structures, which are  connected with its centrifugal tracts,
such as the  crus cerebri (excluding the tegmentum), the pons, and
the pyramidal tracts  of  the medulla  oblongata,' are  the  most
powerful formations in the human brain ;  there seems, therefore,
to be a harmonious dependence between the form of  the brain-
trunk-structures and  the  quantitative development of the fore-
brain.
   These well-ascertained,  though general and incomplete ana-
tomical facts,  would justify us,  from a purely morphological point
of view, in affirming the localization of  cerebral functions.
   Having obtained this firm and safe anatomical foothold, it will 
Critical Review of JMotor  "Areas."           143
be especially interesting to examine those  from among the many
contradictory physiological  experiments which  confirm  the  view
of  a localization  of functions in the  cortex of  the  brain.   This
question has been studied in all its details by different physiologists
and  in  different  ways.   The  older  brain-physiologists  asserted
that  direct  irritation of  the cortex produced  no  effect;  but
Hitzig,1  by means of  electrical irritation, and  Nothnagel,2  by the
use of mechanical irritants (principally pricking with needles), suc-
ceeded in proving that irritation of certain regions of the convexity
produced movements in  the opposite side  of the body.   Ferrier,3
too, has  furnished many details.

     It would be a difficult task to give a critical review of all these experiments, which
agree with each other in principle only, and not in the dimensions of the psycho-mo-
tor,  functional areas governing  special groups of muscles.  Nothnagel operated on
the rabbit, and could not make out as large a number of centres as Plitzig determined,
though Nothnagel's centre for the anterior extremity occupies the same position as the
centre to which Hitzig has ascribed similar functions.  On the other hand, Nothnagel
has described another possibly motor (leap) centre, which Hitzig  cannot corroborate ;
and the difficulties of a critical review are increased still more by the fact that Hitzig,
experimenting on monkeys, wishes to  limit all  centres to  the gyrus /nrcentralis, in
flat contradiction of his description of the motor areas  in dogs, in which the facial
centres, as well as those for the straight ocular muscles, are situated posteriorly to the
fissura centralis.
     No one will be disposed to  agree with Hitzig's complicated interpretation of the
gyrus praecentralis in the dog, and yet,  in spite of the artificial expansion of the gyrus
praecentralis over several other gyri, we may locate the centre for the muscles of the
neck and trunk in front of the  gyrus praecentralis, as Hitzig defines this convolution,
and as was explained on page 18 of the previous section.  No mention is made of this
particular motor area in the brain of the monkey.
     Ferrier's " centres " cover the largest area, extending from the middle frontal con-
volution over and beyond both central convolutions as far as the occipital fissure, and
including the first temporal convolution.   By way of anticipation, I will remark that
Munk also looks upon a line drawn from the posterior end of the Sylvian fissure to the
margin of the hemisphere as the posterior boundary of the motor area of the cortex.
The radiating fibres which we observe  entering  the nucleus lenticularis and capsula
interna, on longitudinal sections of the brain (Fig. 30), would seem to be radiations from
that portion of the  cortex which lies anterior to and including the region of the pos-
terior central convolution, into  these centrifugal conducting tracts.   Hitzig's centres
are located principally in the frontal lobe, although he has made an entirely gratuitous
change, as was shown in the previous chapter, in making the gyrus pracentralis  part
of the parietal region.

     1 Fritsch u. Hitzig: " Ueber  die elektrische  Erregbarkeit  des  Grosshirns,
DuBois-Reymond's  Archiv, 1870.  Hitzig :  Untersuchungen zur  Physiologie  des
Gehirns, ibid., 1873.  " Untersuchungen des Gehirns," Berlin, 1874.
     3 Virchow''s Archiv, vols. 57 and 58.
     9 " Experimental Researches in Cerebral Physiology," 1873 ; cf. also "Functions
of the Brain," Am. Ed., 1876. 
144
Psychiatry.
   Hitzig has mapped out the  centres in the praecentral convo-
lution in the following order of succession from above downward :
(i) Centre  for  the posterior extremity ; (2)  for the anterior ex-
tremity;  (3) for the facial  nerve;  (4)  for  the  movements of
mastication.  The disagreement among authors in  regard to the
topographical distribution of psycho-motor centres in the cortex
makes it incumbent upon us to examine into the nature of those
motor disturbances upon which all are. agreed.   In parenthesis
be it said, that  Ferrier's " centres " have met with opposition from
all other authors.
   Hitzig  believes  that the motor  disturbance in the  anterior
extremities, consequent upon an excision of  cortical substance, is
to be explained onthe ground that the animal has lost the muscu-
lar sense which informed it  of the position  of its  extremities.
An animal, thus operated, will allow its foot to be placed in the
most  uncomfortable  position, with the  dorsal surface  to the
ground, and so on, and yet is able to use the anterior extremity
well enough in  response to volitional impulses.
   Nothnagel is inclined to the opinion that ataxic movements
result from the lesion of the so-called psycho-motor areas of the
cortex,  agreeing with Leyden, who attributes ataxia (i. e., the
condition consequent upon the disease of the posterior gray col-
umns of the spinal cord, which effects irregularities in  lifting, and
in the forward  and lateral movements of the foot) to an inter-
ruption in  the nerve-tracts issuing from the brain.
   The  present author believes he was  the first one  (in the
pamphlet entitled " On the Twofold Cerebral Origin of the Spinal
Cord," 1869) to insist that the processes of innervation from the
hemispheres, which constitute what we term  volitional acts, are
nothing  more than the perception  or memory of  the sensations
of innervation; for  such a sense  of innervation accompanies
each  reflex act, and is  registered  in  the  cortex ;  there  this
same  sense of   innervation serves  as  a   fundamental basis for
similar secondary movements produced by excitation of the fore-
brain.
   By association, these memories {Erinnerungsbilder) acquire suffi-
cient intensity  to excite  secondary movements starting from the
fore-brain and passing along centrifugal nerve-tracts.  I shall refer
to this subject again later on.
   Munk '  has given a very  lucid  account, based upon  experi-
1 Ueber die Functionen der Grosshirnrinde.  Berlin, 1SS1. 
Sensory Character of 'Motor Centres.        145
ments, of the relation of the cortex to the movements of the body.
Munk subscribes to my views, believing that  in order to explain
conscious movements—volition, in  psychological phraseology,—it
is sufficient to postulate sensations  of innervation.   Munk dis-
tributes sensory areas over quite the whole of the cortical surface,
and therefore terms  the region from the occipital lobe  to very
near the frontal margin (in the monkey) the "sensory sphere " of
the brain.  The  character of these sensations he  described as
tactile sensations, sensation of pressure (the knowledge of  which
is not enhanced by experiment), and as sensations of innervation.
The tactile and pressure sensations are thought to be a means of
regulating the excitation of sensations of innervation. Spiess and
Lotze entertained the same opinion  long ago, but were too one-
sided in supposing that the " muscular sense " depended simply
upon the perceptions  of touch and pressure by any part of the
skin and the joints.
   Thus  we see that an experimental  investigator reaches the
conclusion, that sensitiveness is the only specific energy common
to ganglion cells ;  and we are led to infer a localization  of  sense-
impressions only,  which, in keeping with the above  views,  would
be synonymous with the localization  of so-called motor areas of
the cortex.
   In corroboration  of the conclusions  of Hitzig, who observed
that  blindness ensued upon the removal of a part of  the  occipi-
tal cortex,  Munk finds that  removing  a  piece  (15 mm.  broad
and 2 mm. thick) of  the same region gives rise to  what he calls
"psychical blindness."  Removing  another  piece of about the
same dimensions, from the temporal cortex, caused symptoms to
which Munk gives the name of " pyschical deafness."
   The dog which has undergone the former of the two  opera-
tions, will show the  following peculiarities, provided the healthy
eye 011 the side of the lesion be properly  bandaged.  The dog, so
conditioned, " no longer scents for his food  as  he  used to  do in
the accustomed corners of the room, and if both the mess-pot and
the pail of water  be placed in his way  he will go  round  about
them again and again without taking notice of them.  He  takes
no notice of  his food until he smells it ; neither  a  finger nor
a flame brought close to his eye moves him ;  and the sight  of the
whip, which used to drive him into the corner, does not intimidate
him in the least.  He had  been  trained when the hand was
passed by his eye  to give his paw; now he does not respond to 
146
Psychiatry.
that movement of the hand until he hears "paw" ;  and other like
observations are to be made.  But such a dog can  again learn to
see as in his earlier days, and to regulate his action according to
his visual  images; he is, therefore, mentally blind—not organi-
cally blind; he has lost  the visual images registered in his  cortex
previous to the operation.  This phenomenon, the  revival  of pre-
viously registered images, Munk explains by the fact  that the visual
area is larger than the part extirpated, and that up  to the time of
excision the entire visual  area was not filled with visual images,
but that after the  removal of the  part  formerly entrusted with
the care of the visual images, another part, connected also with
the retina,  assumes the duty of harboring new visual images.   If
the entire  occipital cortex be  removed, cortical  blindness will
ensue ; the animal  becomes totally blind, although the subcorti-
cal visual centres are  intact.   We are, therefore  concerned with
the loss of cortical functions only.
   More recently  Munk's " visual sphere" has been extended
considerably, so as to include in the monkey  the  whole  of  the
well-marked occipital  lobe, including  its  median  surface.   Munk
states, that after psychical blindness has disappeared, in the course
of four to six weeks, the dog does not pounce directly upon meat
which is placed before him, that he cannot snatch it until it  has
become distinctly visible by appropriate  movements of the  head.
He draws the  inference  that after the extirpation of the cortical
centre, a new  blind spot  is created on the retina,  for  a definite
portion  of the retinal  elements is no longer connected with  the
cortical  cells upon which retinal impressions were registered ; and
he contends,  furthermore, that  the  arrangement of the cortical
elements repeats the  exact distribution  of the retinal elements
around the spot of clearest vision.
   The  psychical deafness resulting from the removal of  a por-
tion  of  the temporal lobe, brings  about the following changes
in the behavior of the  dog :
   " The dog  has retained the  power of hearing,  every unusual
noise exciting an  equal pricking of both ears, but he cannot in-
terpret  what he  hears.  The meaning  of ' pet,'  ' come,' ' up,'
'there now,' ' paw,' and  all calls to which he was accustomed  to
respond, he does  not understand ; so  that  he no longer per-
forms movements  which  at one time had the  value of reflex
acts."   Gradually the dog learns to hear again, and after four or
five weeks  behaves about as he did before the operation.  In this 
       Distribution of Different Areas over Cortex.    147

instance also Munk assumes the existence of a peripheral auditory
area around the part extirpated ; this peripheral area now receiv-
ing and storing up the newly acquired impressions.  Removing
this peripheral area and leaving the concentric inner sphere of the
auditory  area,  produces no  effect whatever; for  no auditory
images had as yet been stored  in  the  former (peripheral) area,
as was the case also with regard to the visual centre. This theory
would explain  not only the re-acquisition of facts which had once
been familiar, but also every increase of knowledge effected by
the mediation  of cerebral cells which up to that time had not
been functionally employed.
    To this literal quotation of Munk's views, I wish to add that
they give  a plausible  explanation of  mental (psychical) deafness
only.  The introduction of projections of the macula lutea  into
an inner area of the " visual sphere "  must necessarily lead to in-
calculable  confusion.   This re-acquisition of facts  is simply the
result of newly-registered images which are lodged in the environs
of the parts removed.  According to Munk's theory we should have
to believe that these later impressions were indistinct, because
they did not happen to be registered within the cortical  (projec-
tion) area of  the macula lutea.   Munk  thinks perception  and
memory are identical.   We, hope to prove later on that a cortical
image has no  material background  (sinnliche Klarheit).  Even
darkness leaves its image upon the cortex.   The term " psychical
blindness " would suffice, and from this, cortical blindness would
differ simply in being an incurable state.
    There  is  no reason compelling  us  to assume that  tactile
and pressure-sensations, because of their  relation  to the muscu-
lar sense, are registered in the same parts of the,cortex as are the
sensations of  innervation: first, because the  external fasciculi
(of Tiirck) of  the crus  cerebri, which carry tactile  impresssions,
are not  united to one another throughout  their entire course;
and  secondly, because association-fibres  effect  the co-operation
of widely separated cortical districts.
    Referring once more to that portion of the sensory sphere,
(Fiihlsphare) which was called the psycho-motor centre until Munk
called it the centre of sensations of innervation, Ave  find that this
author ascribed limits to this sphere in the brain of a dog, which, if
followed in the brain of a bear (Fig. 7), would,leave a functionally
useless region  occupying the convex surface between the two
parietal convolutions, and a portion of the marginal convolution 
148                      Psychiatry
above.    The sensory  sphere  would  be  situated   cephalad,
the  auditory  and  visual  areas  caudad,  of  this  functionless
area.  Between this boundary and the olfactory lobe there lie,
one  above the other, the centres for the hind limb, for the fore
limb, and for the head.   In a later publication (December, 1878),
Munk has added to the number of sensory areas in which the sen-
sations of innervation are registered.  These newly added areas are
an eye-region on the summit of the second parietal arch of the dog,
governing the protecting and motor apparatus of the eye ; and an
ear-region on the summit of the  first parietal  arch, removal of
which disturbs or annuls the movements and sensibility of the
concha auris.   The head-region, which he subdivides into centres
for  the  tongue, facial  nerve, etc.,  Munk distributes  over the
whole operculum as far as the  anterior branch of  the parietal
arch.   The  centres for the fore-  and hind-limbs lie in front of
the  sulcus centralis, and together  do not occupy an area larger
than the " head-region."  The centre for the hind-limb lies nearer
to the margin of the hemisphere.    The extremities  being repre-
sented  in the frontal  lobe, Munk locates the  neck-region still
farther to the front, as Hitzig did also, in that part of the frontal
lobe  lying in front  of  Leuret's  transverse  fissure;  while  he
relegates  the trunk-centre  to the  most anterior portion of the
frontal lobe,  resting upon the lobus olfactorius.   With  the excep-
tion of the gyrus fornicatus and the olfactory lobe, a correspond-
ing  portion  of the  median  surface, which  begins  in man in
front of the occipital  fissure, is  appropriated to the domain of
the sensory sphere, including the various muscular areas.  (" Ver-
handlungen der physiologischen Gesellschaft," Berlin, 1878.)
   In the monkey (Fig. 8) the occipital lobe constitutes the visual
sphere ; the temporal lobe presides over auditory functions, as has
'been repeated often enough.  Within the sensory sphere we have
the eye-centre on the posterior (superior) parietal  arch, and the ear-
centre on the anterior (inferior) parietal arch.   The head-region ex-
tends from the margin of the operculum upward as far as beyond
the lower portion of the sulcus centralis, and anteriorly it extends
as far as the sulcus praecentralis, in the concavity of which the neck-
region is lodged.  Above it and partly behind  it lies  the centre
for the hind-limb, along the posterior margin as far as the sulcus
occ.  ext.  The sensory sphere of the trunk is situated in the frontal
lobe, in front of the sulcus praecentralis and in the posterior por-
tion of the orbital surface. 
           The Fore-Brain the Seat of Intelligence.       149

    In keeping with  his  visual and auditory areas Munk estab-
 lishes consistently enough a psychical  paralysis after the removal
 of the so-called motor centres.  This psychical paralysis, which is
 curable, is the result of the destruction of a small amount of cqr-
 tical motor substance ;  but if the peripheral as well as central area
 of a motor centre be entirely  destroyed, then permanent cortical'
 paralysis will be established.
    Munk's sensory centres do  not respect definite, prescribed boun-
 daries, such  as the convolutions would present; but there is this in
 favor of his views, that he rriakes the entire frontal lobe do serviec
 as a sensory sphere.  Other authors, and among them Hitzig, who
 has misinterpreted the results of his  own  experiments, have pro-
 nounced the frontal region to  be the exclusive seat of intelligence.
    On this head Munk justly observes:  " Intelligence is located
 everywhere in the cerebral  cortex and nowhere in particular."   I
 wish to add  in  corroboration  of this view, that no  author of the
 present day  would be likely to insist on one special seat of memory,
 for memory  is the common property of all cortical cells and fibres
 which are able to receive and conduct external stimuli of all sorts.
    Consciousness and intelligence also, which is evolved in the fore-
 brain, depend upon a mechanism,  the minute  details of which
 enable  us to understand  the  restriction of  intelligence  to the
 fore-brain.  This discussion, which we now take up, shall be guided
 by the fundamental experiments of physiologists, and  by certain
 morphological views which I published  years ago (Leidesdorf,
 " Lehrbuch der Psychiatrie," p. 45, et seq.—1865).
    There may  be a difference  of  opinion among physiologists
 regarding the localization of definite impressions and functions in
 the cortex of the fore-brain, and their distribution among the med-
 ullary fibres of the brain ;  but there can be no question about this,
 that the intelligence of an animal is seriously impaired (obliterated)
 by the extirpation of  its  fore-brain.  Those who removed the
 fore-brain with the knife, who destroyed it by freezing, or who, like
 Goltz, trephined the skull and washed  out the fore-brain with a
 stream of water, all are agreed on this one point.  Goltz (Ueber
die Verrichtungen des  Grosshirns,  in Pflugers Archiv, vol.  xiii.
and  xiv.) presents the largest number of striking and  critical
observations,  although  he  removed less of the  fore-brain than

   'The German text has Rindenldhmung.   I have translated it cortical paralysis.
The term is misleading, however: for the " psychical " paralysis is also based upon
changes in the cortex.   It would be better to speak in the one instance of " psychical "
paralysis, and in the other of " absolute " or " complete " paralysis.—S. 
150                      Psychiatry.
 others, for he could wash out' only about as much of the cortical
 substance as is visible after removing the roof of the skull.  But
 on this very account Goltz has supplied facts which support the
 view of  the localization of sensory areas on the cerebral surface.
 He observed a diminution of cutaneous sensibility, of the sensa-
 tions of innervation due to ataxia and impairment of  sight; but
 having left intact the base, and the median surface containing the
 olfactory area, and the  basilar portions of the temporal lobe con-
 taining Munk's and Ferrier's auditory areas, the senses of smell and
 hearing were in no way  affected.  The mere loss of a few grammes
 of cerebral  substance suffices, according  to Goltz, an extraordi-
 narily keen observer, to produce a degree of  idiocy  which he
 recognizes from  the  appearance  and gaze  of the  mutilated
 dog.   Idiocy develops in these dogs to such an extent, that they
 stumble into their meat-pots, bite their own legs, and, not remem-
 bering this experience, repeat  the very same thing from day to
 day.  Not knowing their whereabouts in space, they wander about
 the whole room in answer to their master's call; nor are they able to'
 find with their snouts any portion of their skin which has been teased
 by serres fines, but simply run about restlessly and helplessly in con-
 sequence of the pain ; they are not  bright enough to discover or to
 lift up their whining pups, though they be very near them.
   Apart from the difference  in the arrangement of its nervous
 cortical elements (vid. p.  56, et seq.), the white substance of the hemi-
 spheres has everywhere the same structure ;  and we have shown
 that each hemisphere consists : (1) of projection-systems, which,
 with the aid of gray internodia interspersed among the medullary
 fibres, connect the cortex with sensitive surfaces and  motor or-
 gans ;  (2) it (the white substance) consists of association-systems—
 i. e., of arciform nerve-bundles.  The wealth of such fibres, and
 their variation in length, connecting as they do  near and remote
 parts of the cortex, will suffice, without formulating an anatomi-
 cal hypothesis, to unite any one part of the cortex to any other.
 The phenomenon of mental blindness is exhibited in the case of
 the animal that no longer associates the sight  of the whip  with
 the idea of punishment, or in that other animal (of Goltz),  from
which the right hemisphere had been removed, and which, when
 its right, healthy eye was  covered, took no notice  of a servant
wearing a mask and decorated with red rags; but as soon as its

   1 Goltz has long since abandoned this method of removing cortical substance. (For
his present method see Pflilgers Archiv, Sept. 17, 1881.)  S. 
              Memory—A Cortical Function.           151

healthy eye (connected with the left hemisphere) was uncovered,
pounced upon this fantastic figure, as every normal dog would do.
If an animal has  become psychically blind, it  will recognize the
sound of the whip but not the visual image.
   We may note, therefore, that there is a localization of certain
intellectual  activities dependent upon,  and coinciding with the
localization  of definite sensory areas.   Longet was among the
first  to contend that a  dog which had forfeited its  hemispheres
could be made to swallow  colocynth, show displeasure, and per-
form all  the retching movements which a  disagreeable or  bitter
taste naturally excites ; we must therefore  assume the existence
of sensory perception entirely independent of the fore-brain.
   Schiff, who has given further  details regarding these experi-
ments- of painting the tongue  with colocynth, calls  attention to
the fact that he can again and  again  open the mouth of the ani-
mal, show it the instrument of torture (the brush), without  elicit-
ing  the slightest repulsive  movement;  whereas  young kittens
give indubitable  facial  expression of the disagreeable gustatory
impression they  have received.   Sensory  impressions  are  there-
fore  not wanting;  but the recollection of  previous  pain, the
recognition  of movements  preparatory  to  the infliction of pain,
so-called volitional impulses which would  induce the animal to
escape, all these are wanting.
   In order not to be dealing with intelligence in the abstract, let
us determine  by the  simplest  scientific  analysis the contents of
or, at least, a demonstrable factor of intelligence; and with this  let
us compare  the brain-mechanism.  We shall thus  be able to con-
clude whether the  cerebral mechanism  can, or can not, account
for the manifestations of intelligence which existed prior to the
impairment  of the mechanism.
   First of all, animals  deprived of certain cortical areas (Munk)
or of the entire fore-brain, show no recognition of former impres-
sions; the dog does not recognize the call of his master, nor the
cat the  preparations which are being made to insult her  gusta-
tory nerves.  This non-recognition constitutes loss  cf  memory,
and loss of that special  memory which is based upon the   juxta-
position  of  successively received impressions.  This is memory
of the fore-brain, and must be regarded  as a cortical  function.
   It is  not part of our present purpose  to  dilate upon  other
phases of memory, such, for instance,  as  affect the  entire  or-
ganism, and are independent of the  functions of the fore-brain, 
15 2                      Psychiatry.
though related to other parts of the nervous  system.   Among
these would be classed those phases of memory which are  mani-
fested  by  the  spinal  cord in repulsive movements, the  exact
nature of which is varied, knowingly as it were, according to the
character of a painful, exciting stimulus.
   Lotze  regards this phenomenon  as an  after-effect  of  oft-
repeated innervations of  motor spinal nerves,  responding to
definite stimuli reaching the hemispheres.   Later on  we  shall
refer in detail to this view, to whick Brticke also subcribes.   The
spinal cord of the new-born infant would not exhibit such phe-
nomena.  As long ago as 1867 I  endeavored, in an essay entitled
" Ueber den Bau der  Rinde  und  seiner ortlichen  Verschieden-
heiten," to demonstrate the fitness of the cerebral cortex to be the
seat of memory, by showing that it contained more than a milliard
nerve-cells  which could serve as the functional posts of succes-
sively received  impressions; while in  the retina, in which  after-
images  occur as  the  result of protracted normal  stimuli,  these
images  are not permanently lodged ; for every succeeding  series
of images occupies the retina in its totality, and  finally annuls
the after-effects of  former  images.  Munk's experiments   have
verified this assumption in regard to the nature of cortical  mem-
ory.   They have demonstrated  that animals possess a function-
ally unoccupied region in the vicinity of the visual  and  auditory
spheres, the removal of which (region) produces no effect in regard
to psychical blindness, and psychical deafness;  but  if the central
functional portions of these spheres be destroyed, these peripheral
areas will be  the recipients of new visual  and auditory impressions.
   From this it follows that in the normal (physiological) course
of events, more and more of the cortex is called into  requisition
to receive  new impressions, and  that  upon the increase in the
number of  registered images will, depend the enlargement of the
child's mental  sphere.  It is  very probable  that the  number of
cortical cells fixes the limits of  memory—the  foundation  of all
intellectual activity.
   The recollection  of former experiences, of which the animal
that  has forfeited its fore-brain is  incapable, implies the association
of one phenomenon with some other.  The dog, for instance, would
associate the sound of the whip with the bodily pains it inflicted.
In examining the structure of the hemispheres,  and remembering
that  different, distinctly  limited  and functionally separated  por-
tions of the cortex receive  impressions from the various senses,' 
          The Induction-AIechanism in the Brain.       153

we may naturally infer that the  association-bundles, the fibrae
proprice of the cortex, which form anatomical connections between
the different cortical regions, effect the physiological associations
of the images which are stored in these various parts;  these
images implying excitation of the cells of these parts.   Since these
medullary bundles are beyond  a doubt conducting  nerve-tracts,
this interpretation is not a mere hypothesis.
    But recollection constitutes a process of induction (Schluss-
process).
    Wundt was justified in calling an induction the fundamental
logical function (vide his  lectures " Ueber Menschen  und  Thier-
seele ").   I was the first one to demonstrate the association and in-
duction mechanism of the fore-brain, in my pamphlet on the " An-
atomie der  Hirnrinde  alsTragerdes Vorstellungslebensund deren
Verbindungsbahnen,  1865,"  which  was reprinted verbatim in
Leidesdorf's " Manual."  Both ends of the  association-fibres are
connected centrally with cortical cells ;  the  projection-bundles
(vide pp. 42, 43),  consisting chiefly of fibres of the corona radiata,
spreading into the medullary substance of the fore-brain,  conduct
to the cortex the excitations from the external world, and distrib-
ute them over its different sensory spheres.   All objects which, as
soon as perceived, engage two different sensory spheres, may well
serve to prove the existence of  an induction mechanism, present
everywhere in the brain, and anatomically  dependent upon the
association-, and  projection-systems.  John Stuart Mill, who  cer-
tainly possessed  no anatomical  knowledge of this sort, furnishes
a  simple instance of  this process  of induction.  A person who
would happen to find a  watch on  an  uninhabited island would
infer not only that  this island possessed a fauna and  a flora, but
that  man must have  been on this island ; for the idea of a clock
or watch is inseparable from the  idea of a human being.  To this
I will add  the example I employed in Leidesdorf's  " Manual."
Let us imagine the cortex to be a tabula rasa, and let us present
to it a phenomenon which, perceived  by two  different  sensory
surfaces,  would,  through the mediation of  the  corona  radiata,
stimulate two distinct areas of  the cerebral  cortex.  Let  the
phenomenon in  question be a  lamb, and  let us suppose that it
emits a  bleating  sound.   The sight of the lamb will stimulate
cells of the  visual area, and the bleating sound will arouse cells in
the auditory sphere.   The lamb disappears and  the two kinds of
images which it caused to be registered will grow fainter. 
154                      Psychiatry.
    If, in  the course  of  time,  one of these registered images be
 revived,  through the bleating,  say,  of  the lamb hidden  in  a
 stable, then  not  only the auditory, but the visual image also of
 the lamb will be reproduced.   In the cortex an inference is made
 from the  sound to the body that gave forth the sound.  We can
 readily understand  this  process of  induction, if we will  but
 assume  that  the  original  excitation  of  both  sensory areas
 included  the excitation of those  arciform bundles which united
 the  cells  of  the  visual and auditory areas of the cortex, which
 areas had in  turn received stimulating impulses through  the pro-
 jection-bundles.  In  this way both registered images are associ-
 ated, and whenever  the one of them is re-excited, the  excitation
 will extend along the association-fibres to the other cells, which
 on a previous occasion had been taken out of a condition of repose
 simultaneously with the  cells harboring the former image.  The
 association-bundles may  be compared to a connecting thread,'
 which enables one image  to  lift  the  other, as it were, over the
 threshold of  consciousness.
    Inferring one attribute of a phenomenon from the presenta-
 tion  of  another attribute,   constitutes   an  induction;  it  is  a
 recognition in the direction  of causality, for the bleating sound is
 taken to be the result of the presence of the lamb.  And here it
 will  be well  to add  that, though the seats of these  registered
 images are connected with  many other cortical regions,  there is
 no need  of supposing that  all these association-bundles will be
 simultaneously excited.  In the first hypothetical case we supposed
 that the perception, the recognition of these images, or  the induc-
 tion regarding them, were effected by a brain in which no other
 images had  as yet  been registered  in  any  part  of  its cortex.
 In that event, of course,  but one association could  be estab-
 lished.
   A second, not nearly  so hypothetical a case, will show us that
 not all the existing association-bundles connecting certain groups
 of cells with other cortical regions need  be called into  activity
when any one member of the associated groups receives an exter-
 nal stimulus.   In spite of the existence of numerous functionally
perfect  connections   between such cortical groups and others,
recollection  is due  to the excitation of accessory impressions
(simultaneous sensations), which were registered simultaneously .
with the  impression just reproduced, and which were established
with especial reference to the revivified image.   In the example 
       Spontaneous Movements : Subcortical Centres.     15 5

cited above, the visual  image of the lamb was inferred from the
sound ; this can be explained by assuming that the visual image was
an accessory impression, a sensation, received simultaneously with
the perception of the bleat.   Hence we argue that in real cases of
numerous and complicated associations in various cortical regions,
recognition depends upon the re-presentation of accessory sensa-
tions which had entered into a union with certain registered im-
ages. Among its numerous associations each  registered image may
be considered to be a special group of simultaneously perceived sensa-
tions.   We shall  see that  this is analogous to the recognition of
single retinal areas through accessory sensations, through local signs,
the contents of which comprise sensations of innervation, by means
of which the perception of space is effected in the cortex.
   A  person who  met with some stirring experience on a large,
monotonous meadow,  will  recall, in passing over this meadow,
the  very  spot at  which this occurred ; but all other parts of the
meadow he  will not be able to identify  in this way,  With this
one spot impressions and secondary presentations have  been asso-
ciated, which will serve as local signs for recognition of this one
spot in the midst  of this uneventful barren meadow.   It is safe to
suppose in regard to all inductive processes, that certain obstacles
which impede the excitation of cells in full repose are very much
lessened after a single, and particularly after repeated, identical
excitations of association-bundles uniting the cells of two distinct
areas of the  cortex ;  while the transmission of such  stimuli  to
association-tracts, which have been called upon to  unite other,
previously established, groups of associations, becomes wellnigh
impossible.   We may add that Wundt,1 in his great psychological
work, has adopted the term, " association-bundles."
   Another characteristic of animals which have been deprived of
the cortex is the lack of so-called spontaneous movements ; move-
ments not of a reflex nature, but resulting from cortical impulses
which seem  to bear the stamp of volition (freedom), and are not
caused by undoubted momentary impulses.  They are  the result
of innumerable registered  images,  the residual-effects  of  past
motor stimuli.
   We are told also, on the authority of Goltz, that animals which
have had the medullary substance of their hemispheres removed (by
a stream of water) were able to walk; in these cases subcortical
motor apparatuses must  have  remained  functionally  intact.

           x " Grundziige der physiologischen Psychologie," 1873. 
156
Psychiatry.
Longet, Schiff, and Goltz report that animals without hemispheres
were able to fly  and swim, and Goltz  found that the frog could
move forward well enough, as long as the mesencephalon and
cerebellum were  undisturbed.  Plainly then co-ordinated move-
ments  may be initiated by subcortical centres ; and these move-
ments responding to momentary  stimuli, among  which we must
class the retinal image, will come under the heading of the primary
mode of movement.
   It was stated above that  all  excitations  of  the  fore-brain
are secondary.  By reason of the anatomical connections, at what-
ever level, between the cortex and subcortical  centres,  memories
of innervation are deposited in the former, which record the active
processes of the  latter.   Every registered image,  in fact, depends
upon impressions received primarily in the subcortical centres.
   Let us illustrate this by analyzing the act of conscious closure
of the eyelids.  Let a  sharp  instrument touch the  conjunctiva
of the eye (O., Fig. 59);  the impression of this will be conveyed by
the tract Va. 5 to  the trigeminal centre in the pons.  A subcortical
centre of the seventh nerve (7) is connected with the former, which
will transmit this stimulus to a facial branch in the tract Vila.,
in fact to  the  facial branch ending in the sphincter palpebrarum
(Sph.).  Three impressions will also be  recorded in the  cortex.
   1. The image of the sharp instrument conveyed by the tract
II. aa EII.
   2. The sensation conveyed by the  trigeminal branch of the
conjunctiva and carried  by the route a5 EV.
   3. Sensations of  innervation,  transmitted  by the closure  of
the lids to the cortex through the tract 7 a  J7.
   All of these  simultaneously excited cortical centres will  at
once be united by association-bundles, and in the following order :
The visual centre which received the  image of the sharp needle
will be joined  to the trigeminal centre of the stimulated conjunc-
tival branch ;  then, again, the visual  image of the needle will  be
joined to the innervation-centre of the facial branch supplying the
sphincter palpebrarum ; and, lastly, the above-mentioned trigeminal
centre will be  united to the said centre  of facial innervation (J7).
   In this illustration we have proceeded on the  supposition that
this  is the first impression of conjunctival irritation which the
child received, and that those images, which  were  conveyed  by
the tracts described above,  were aroused and associated with one
another in the cortex. 
            Explanation of Conscious Movements.         157

    If hereafter  a needle  should  happen to be brought close to,
without injuring, the conjunctiva of the child, the image of the
needle will revive the  sensation of pain in the conjunctiva, and
with the image of the needle there will be associated also the sen-
sation of innervation of the facial branch ;  thus the mere sight of
the needle will suffice to excite the act of innervation within the
fore-brain.   The association-bundle  EII. ]y. conveys the optic
stimuli to  the centre of  innervation, and this may be re-inforced
by stimuli conveyed along  the tract connecting the trigeminal
centre with J7.   The recognition of the needle, and an  inference
                              fig- 59-
     Diagram Explaining the Mechanism of Conscious Closure of the Eyelids.
    0. Eye.  Sph. Sphincter palpebrarum.  L. Levator palpebrse superioris.  nuc.
Laud.  Nucleus caudatus.  nuc. b. Nucleus lenticularis.   Th. Thalamus. Q. Corpus
quadrigeminum.   Lbl. Cerebellum.  MC. Medulla spinalis.  3, 5, 7. Central nuclei
of the III., V., and VII. nerves.  II. Optic nerve.  III. Third  nerve (n. oculomo-
torius).  V. Trigeminal.  VII.  Facial.  Jdv. Individuality.  J3,  [7. Cortical centre
of innervation for III. and VII.  nerves.  EV. Cortical centre of  Trigeminus.  EII.
Cortical centre of the optic nerve.   Lines marked a denote centripetally conducting
projection-fibres; b., c. centrifugally conducting proj.-fibres.  Red lines denote as-
sociation-fibres (systems).

as to the pain it inflicts, will, without any further injury, produce
a closure of the  eyelids  through the centrifugal tract, ]j. by., by
means of a volitional impulse starting from the cortex.
    The  cortex and subcortical centres may, therefore, be said to
possess  a  mechanism  which, intelligently unites two motor acts
occurring  at  different times.   Without  such a mechanism con-
scious movement would  remain inexplicable.   The cells of  the
cortex are endowed  merely  with the  power of  perceiving  the
origin of  sensations  of innervation  ; but the  cortex  could  not 
                                     Fig.  60.

     Diagram Explaining the Mechanism of a Conscious Movement of the Arm.


    F. Frontal cortex.  ccO. Occipital cortex.   CN. Nucl. caud.   LN. Nucl. lenticu-
laris.   hT. Thalamus opticus.    D. Mesencephalon.  L.   Pons Varolii.  O.   Med.
oblongata, characterized by the olivary body.  M. Medulla spinalis, terminating with a
cross-section of the cervical spinal cord.  cd. Cerebellum.   Blue lines indicate centrip-
etal ;  red lines, centrifugal tracts ; the  red  and  blue circles in the spinal cord and
fore-brain denote the central gray nuclei ; black lines mark the association-fibres. 1 ai.
Sensory tract of the arm.  B. Part of the  cortical  centre  for cutaneous sensation.
2.  Tract for effecting the movement  of the arm.  3A. Conducting tract of the optic
nerve.   A. Part of the visual  centre.   4C.  Tract conducting sensation of  innerva-
tion, interrupted in the thalamus.  C.  A centre in the cortex for sensations of inner-
vation.   5.  Centrifugally-conducting tract,  originating in the cortical area C.
158 
               Secondary Form of Movements.           159

originate  movements,  if  the  innervation-sensation  of  definite
forms of movement were not conveyed to it from subcortical centres
by the primary form of movements.  In consequence of its connec-
tions with subcortical centres, and as a result of the sensations of
innervation deposited in its substance, the cortex becomes a spec-
tator of the reflex acts evolved in the subcortical centres.  And thus
we find,that, in the normal brain, no reflex actions can be performed
without exciting to action the second portion of this mechanism—
namely, secondary volitional movement which  no longer requires
the stimulating influences of a reflex action.
   The influence of innervation-sensations on centrifugal nerve-
tracts is explained by  assuming the former to be images regis-
tered in the cortex ; and that the assumption is a  correct one is
rendered probable  by the fact that  intense volitional efforts may
be directed to paralyzed muscles, without producing the slightest
contractions in these muscles, thus proving that the innervation-
sensations in question do not arise from a perception of muscular
contractions, but  from  sensations  which the reflex centres,  in
their  capacity  as subcortical sensory centres for motor-sensations,
transmit to the cortex of the brain.
   The sensation of  innervation  which reaches the cortex, and
from  the cortex  innervates centrifugal  nerve-routes,  does not
present the fundamental motor-images;  for the  registered  im-
ages, and the  sense-perceptions are  altogether incommensurable.
Furthermore,  if  for the term  " registered images " we should
substitute the expression " presentation," we would find that in
these instances of  secondary stimulation of  the fore-brain, the
presentation of sensory impressions, be they ever so intense, does
not in the least reproduce the image of the original  (primary)
sense-perception.  This is true also  of the  sensory images of the
innervation-sensations, which are distributed over various cortical
regions as motor presentations (Bewegungs vorstcllungen).
   We must look for the indirect causation of even the remotest
effects of  cortical movements in  the  centripetally-conducting
sensory nerves.  Using a former simile, and comparing the gan-
glionic cells of the central nervous system to living organisms, we
may say that stimuli acting upon their tentacles invariably produce
excitation of the claws, and movements of their muscular apparatus.
The light of the sun produces contracture of a muscle of the iris,
the constrictor pupillae ; and if it be excessive, it will bring about
closure of the eyelids.  Sensory fibres of the optic nerve convey 
i6o
Psychiatry.
this stimulus through nerve cells and motor fibres connected with
these muscles,  the optic stimulus thus extending beyond optic-
nerve  cells.  The optic  nerves  supplied the primary motor im-
pulses, and gave rise in the first instance to the cortical sensations
of innervation.   Conscious closure of the eyelids is, therefore, an
after-effect of the  intense sunlight  which  stimulated the  optic
nerve.  Whence it follows that the motor effects of our conscious-
ness reacting upon the outer world  are  not the result of forces
innate in the  brain.  The  brain,  like  a   fixed star, does not
radiate its own  heat; it obtains the energy  underlying all cerebral
phenomena from the world beyond it.
    The secondary order  of movements, hitherto described, com-
prised mere repetitions of movements which were primarily part of
reflex actions.  The reflexes had been transplanted to the fore-
brain, and naught but the means of exciting such movements from
the fore-brain had been changed.  The initiatory impulse was con-
veyed by the  association-bundles.  But  in the fore-brain  any
order of movements can form an indefinite number of associations,
and so the associations engendered by reflex movements become
part of the whole mechanism of association.  The result is, that
movements which  were originally reflex in character can be set in
action by any one  of a larger number of associated impulses.
    In order properly to understand the relation between primary
and secondary movements, it will be  wise to give another illustra-
tion ;  for  in  the  former  illustration we failed  to  explain the
anatomical substratum of  the  functional activity of subcortical
centres with regard to the sensations  of innervation and the motor
impulses.
    Let  us  suppose a flame to have  injured the hand of a child,
and that the latter withdrew the hand from  the  flame.   This
movement (the withdrawal of the hand) will be effected, without
the intervention of conscious impulses, by  an impulse conveyed
from  the injured part by  the  centripetal  tract I (Fig. 60), and
transmitted through a spinal-cord centre along the path 2, which
withdraws the hand from  the flame.  This movement and the
altered position of the arm are indicated by dotted  lines.   The
following records of this act will be transmitted to the cortex
through the agency of the projection-systems :   First, the visual
image of the flame from the eye along the tract 3A.; secondly,
a painful sensation from the injured part along the tract 4B.   This
nerve-tract passes  uninterruptedly through the cerebral ganglia 
        Optic Thalamus and the Upper Extremity.     161

and the capsula interna to the occipital lobe, as is evident from a
study of the course of the outermost and posterior bundles of the
internal capsule  (p. 4, Fig. 5, POM.; p. 85 ; Fig.  22, Tm.).
   Thirdly, the  sensation of innervation resulting from the reflex
movement.   The interruption of this tract in  the thalamus is in
accord with  the physiological  fact, that  the  movements of the
upper extremities are influenced by this ganglion, but that destruc-
tion of the thalamus is not (necessarily) followed by an interruption
of the tract conveying cortical impulses to the  muscles of the arm.
   The innervation-sensation C. acts through the centrifugally-
conducting tract 5 upon the central origin of those anterior roots
which, through  reflex excitation, protected, the arm against the
flame.  This central origin of the anterior roots is controlled  first
by primary motor impulses carried  to it by the  posterior  spi-
nal roots, and secondly by  secondary motor impulses  emanating
from  the cerebral cortex.  Since the  centre C. is connected with
the association-bundles CB., CA., and the latter with one another
by the bundle BA., the child need not actually  burn its  hand again
before guarding against the  flame ; but the memory of the flame
and of its effect (through association  with the centre in which the
painful sensation has been stored), will suffice, through the one or
the other of these associations, to initiate a movement which will
put the arm beyond the reach of the flame.
   We have taken our illustration from  the  movements of the
upper extremity, because in so doing we can  refer to  a ganglion
which we know  positively to be connected with this  extremity,
and to be intercalated in the path of its sensations of innervation.
This ganglion is the thalamus opticus.
   The optic thalamus is not a ganglion of the fore-brain.  All pa-
thologico-anatomical lesions prove that the lenticular nucleus is
the ganglion of the fore-brain, which conducts cortical impulses
from  the one hemisphere to the anterior roots  of the opposite
side of  the body.   Nothnagel has given the most accurate proof
of this by observing  the condition  of rabbits after he had de-
stroyed their lenticular nuclei by means of chromic-acid injections.
He reports that the animals acted as though their hemispheres
had been rernoved.  They  exhibited  not  a sign of spontaneous
movements, and yet irritation of the skin caused them to leap for-
ward.  Nothnagel proved also that complete destruction of the
thalamus did not  in the least impair the  movements  of the ani-
mal, and  that consequently centrifugal nerve-tracts between the 
l62
Psychiatry.
cortex and the anterior roots did not pass through the  thalamus.
In a case of right hemiplegia I found symmetrically situated cysts
(of the size of a hazel-nut) in each thalamus.   These symmetrical
lesions of  the thalami could not account for the hemiplegia, but
Basal Surface of a Brain-Axis with Tubercular Tumor of Right Side.
    I. Island.  T. The cut temporal end of the corona radiata.  F. The cut frontal
end of same.  II. Optic nerve and tract.  P.  Pedunculus cerebri, broader on right
side, and passing without a definite boundary line into the region of the lamina per-
forata posterior ; crowding at the same time the right half  of the pons backward.  V.
Pons Varolii.  O.  Oblongata.  Cb. and Cbt. Cerebellum.  The left half of the cerebel-
lum is larger in volume in consequence of a tumor enclosed within.

I found in addition to these a unilateral lesion in the left nucleus

lenticularis.  This observation shows of what  little  moment the

thalamic  lesions  were,  and what  great importance was  to be 
                       Lesion of Thalamus.                   163

attached to the unilateral  destruction of  the nucleus lenticularis.
Yet, on the other hand, Nothnagel was  able to infer from his ex-
periments  that extirpation of  the thalami, like the  removal of
the innervation-centres of the cortex, seemed to produce a condi-
tion in which  the animals  remained ignorant of  the position of
their extremities,  from which  it  follows  that the optic thalami
                                Fig. 62.

               Dorsal Aspect of Same Brain-Axis (vid. Fig. 61).
    I. Island.   Nc. Nucleus  caudat.  Th. thalmus.   III.  Third ventricle.   Q.
Corp. quadrig.   V. Valvula cerebri.  P.  Region of lemniscus and processus cerebelli
ad cerebrum.  The right corp. quadrig. is flattened ; the left is crowded away from the
median line ; furthermore  the broadened  thalamus was pushed to the left.   The
third ventricle is not mesial.  Two incisions, one into the corp. quadrig., the other
into the optic mass, enabled us to inspect the convex surface of the tumor, which had
attained to the dimensions of a pigeon's egg. 
164
Psychiatry.
are a signal-station (Wundt) for sensations of innervation, akin to
those contained in certain cortical centres.
   According to the experiments of Longet, Schiff, and Nothnagel,
incomplete and unilateral lesions of the thalamus  influence the
position of the head and the upper extremities.  The muscles of
the spinal column turn  these  in such a manner that the  head
looks toward  the  healthy thalamus; while on  the side of the
healthy thalamus the flexors of the upper  extremity, and on the
side of the lesion the extensors of  the upper extremity, appear
contracted.
   From the description given in the previous section of the thala-
mic origin of the tegmentum (p. 90, et scq. and p. 132), we learned
that decussating and non-decussating fibres passed from the thala-
mus to the spinal cord ; the decussating fibres through the poste-
rior commissure, the non-decussating  through the laminae medul-
lares, which originate, in radiating fashion,  from  the thalamus.
   As this twofold thalamic origin of the spinal cord holds  good
for its relation to the upper extremities, we  can readily understand
that both upper extremities should be represented in one and the
same thalamus.  The deviation of  the upper extremities and the
turning of the head toward  one  side  account  for the  manege-
movements  of operated animals.  This circular movement is lost
in a very few days, and after that  the animals which have  been
thus operated upon show no sort of paralysis.
   In the year  1872, I  had occasion to  observe a five-year-old
boy, who was affected with a large tuberculous tumor (figs. 61 and
62)—of the mesencephalon and the thalamus.    The diagnosis
was  easily made, for the boy showed marked  paralysis  of the
right third  nerve, and  slight  paralysis of the  left facial nerve,
and  of  the left  extremities.   The architecture of  the mesen-
cephalon  (fig. 41), and  particularly the  origin of the third pair
of nerves, lead us to infer the  dependence of such a grouping of
crossed paralyses upon lesions affecting the right crus cerebri and
the  third nerve.   In addition to  the above symptoms, it was
noticed that the head of this boy was turned toward the left  side;
and  that, while at  rest, there was  flexion of the left upper ex-
tremity,  and  extension of the right upper extremity;  a rel-
atively great  resistance  was required  to counteract  this  flexion
or extension.  From this circumstance it was fair to suppose that
the tumor involved the right  thalamus opticus.   Figs. 61 and 62
represent the post-mortem appearances. 
Symptoms from  Thalamus Lesion.         165
    Whenever this  boy was otherwise occupied, this compulsory
position of the head and upper extremities disappeared; and, in
spite of the paresis of the left facial nerve and of the extremities,
he played quite naturally with the objects which engaged his at-
tention for the time being.
    A lesion of the  thalamus does not produce paralysis, and for
this reason we cannot agree with Schiff, who supposes  that  rota-
tion of the  head to the right results from paralysis of the left
rotatory muscles of the spinal column, and that the flexion of the
right arm was due  to a paralysis of  the  extensor  muscles of the
same arm ; and extension  of the left extremity, to a paralysis of
the left flexor muscles.   But this typical pathological  position
following upon a thalamic  lesion will admit of a different explana-
tion.  We may suppose that the boy,  lacking the  innervation-
sensations of the left rotatory muscles of the spinal column, was
induced to  excite  the missing  sensation  of  innervation  by  a
volitional rotation, to produce the lacking sensation of innervation
of the  left-arm flexors, by forcing a flexion of this arm, and under
similar circumstances to compensate for the disturbed sensation
of innervation of the right  extensor muscles by exciting a forcible
extension of the right arm.
    The lack of innervation-sensations created  delusions with re-
gard to the position of  his extremities, which in turn gave rise to
volitional movements,  in consequence of  which he assumed the
typical pathological position, the so-called forced position.   If
he  had been  a  quadruped  this position would  have  been fol-
lowed  by circus  movements.  Making use of  our knowledge of
the twofold, asymetrical origin of the spinal-cord bundles in the
thalamus, we conclude that the rotatory muscles of the  spinal col-
umn and  the flexors of the  upper extremity are  represented by
bundles which decussate below the thalamus, whereas the extensor-
muscles of the upper extremity are represented by direct bundles
from the spinal cord to the thalamus.  In my pamphlet  published
in 1869, " On the Twofold Origin of the Spinal Cord in the Brain,"
I showed  that the origins of the tegmentum and the ganglia of the
di- and mes-encephalon were not connected with the centrifugal
nerve-tracts of the fore-brain, but that they served to initiate the
primary forms of  movements, as we conceived of  them above;
that on the other  hand the nucleus  lenticularis was connected
with no centripetal tracts which could possibly convey reflex
stimuli to it, but  that in accordance with all pathological data as 
166                      Psychiatry.
well, it carried the motor impulses from the cortex ;  and increas-
ing with the dimensions of the hemispheres, attained the greatest
magnitude  in  man.  As a  corroboration  of  this view,  I  have
found the area of  the tegmentum which  contains the spinal-cord
origins  from  the  di- and mes-encephalon,  relatively  and  abso-
lutely more developed  in animals than  in  man.  The secondary
movements which receive their  innervation from the fore-brain
are effected, therefore,  by  nerve-tracts, which  pass  through the
nucleus lenticularis (Vide  Wiener med. Jahrbiichcr, 1872).
   Soltmann ' has discovered a physiological fact which postulates
the necessity of finding  the origin of conscious  movements.   He
has found that those regions of the cortex which if stimulated in
the adult brain produce  muscular movements, are  in  the  new-
born animals unexcitable and " not yet motor " in function. But as
the reflex  movements are perfect in these very young animals
from the time of  birth,  we are doubly justified  in believing that
the reflex movements constitute the primary form of movements,
and that centres for the innervation of  the secondary forms are
established later, and are derived from the sensations of innervation
connected  with the former class of movements.  That centripe-
tal tracts connecting the cortex with the subcortical centres for
sensations of innervation, such as the thalamus, constitute the ana-
tomical link in the chain producing secondary movements, is my
own well-established conclusion, and  one  that is supported by
Soltmann's discovery.
   In its relation to  the upper extremity  the thalamus was shown
to be a motor mechanism, through the agency of which decussat-
ing and non-decussating representatives of certain muscles effected
certain definite forms of motion.   This was demonstrated by the
nerve-tracts of the case  pictured in Fig. 60.  The nucleus lenticu-
laris, which, with  its second division of the  projection-system
(p. 27), winds  around the inner  side of the pes pedunculi as the
ansa peduncularis (constituting the innermost and most posterior
of its bundles), and  in  part  traverses this same pedunculus, in
order to reach the stratum intermedium and the substantia Soem-
meringi behind the  pes pedunculi ; this  nucleus lenticularis, so
connected, effects  movements only on  the  opposite side of the
body.  The point at which this  impulse  crosses to the opposite
side is  not  to  be  looked for in the decussation of the pyramids,

   : Jahrbuch f.  Kinderkrankheiten,  N.  F., IX.   Experimentelle Studien fiber die
Functionen des Grosshirnes des Neugebornen. 
Sensation of Innervation.               167
but since I proved anatomically (p. 136), in unison with Tiirck's
processes  of  degeneration  after  destruction  of  the lenticular
nucleus, that the stratum intermedium is transformed in the spinal
cord into the  innermost bundles of the anterior columns, it must
be looked for  in the anterior commissure lying next to these.
   There is still a third grade or order of innervation from move-
ments of the body which must engage our attention.  The move-
ments of this order, like those of the second  order, are initiated
through  the mediation  of  the  association-mechanism  from  the
cortical  centres of  innervation.   They  are  distinguished from
movements of the second order  by the fact that the form of move-
ment is not a mere repetition of reflex movements, and that amid
circumstances, and  after stimuli, which would produce a definite
form of reflex movements, or which would excite secondary cortical
movements, copying  the  form  of. movement prescribed  by the
reflex,—under such circumstances  entirely  different  forms of
movement  would  be  initiated  in the cortex.  Thus a cool  and
collected person, who  submits to an operation on his eye, will, in-
stead of allowing  the  sphincter  palpebrarum to act as soon as the
knife approaches the eye, be able to keep  the eye wide open by in-
nervating the levator palpebral superioris.  Mucius Scaevola, of legen-
dary fame, was able to retain his arm in the sacred flame, instead
of withdrawing  it  in obedience to the ordinary reflex excitation.
    The  first of these two instances is explained in  Fig. 59.  From
the cortical centre for the  innervation of the (musculus)  levator
palpebroe superioris  (J3),  the roots of the third nerve may be
innervated  through the tract J3 C3  in  response to irritation of
the conjunctiva;  whereas irritation of the conjunctiva ordinarily
produces a reflex movement of the sphincter palpebrarum ;  this
primary form of movement is followed by conscious closure of the
eyelids—the secondary form. Consequently we may say that the
innervation centre of  the third nerve is controlled also by stimu-
lating tracts, giving rise to  movements which have  no prototype
in the reflex  mechanism.   The innervation centre for the third
nerve is  anatomically connected with a number of mutually asso-
ciated centres arbitrarily drawn in Fig. 59 which should be repre-
sented as distributed over the entire cortical area.  These centres,
connected with  one another by  every variety and length of asso-
ciation-bundles, are nothing special, their " memories " are defined
by the  peculiarities  of  localization referred to  above.   The
sum  of these  " centres"  constitutes the  " individuality,"  the 
168
Psychiatry.
" ego "  of abstract-psychologists.  I attach some importance to
the word " individuality,"  because it  is founded upon  the ana-
tomical structure  of the cortex, and  the  simple physiological
process which enters into our present  discussion.  Individuality
implies the  sum of firmest associations, which  under  ordinary
circumstances are wellnigh inseparable ; the aggregate of " memo-
ries " forming a solid phalanx, the relation of which to conscious
movements can be defined apparently with mathematical precision.
This unequal activity of the fore-brain,  constituting individuality,
varies  as regards contents  and  degree with each  person ;  it is
designated also  as  the  character of the individual.  It has been
justly observed, if  the character (individuality) of a person were
entirely known  we would  be able to  predict  the thoughts  and
deeds of such an individual, however complicated they might  be.
   The observation of Munk quoted above, and the conclusions of
experimental physiology, strengthen the opinion that intelligence
is not limited to definite cortical areas,  but that, being based upon
perceptions including the sensations of  innervation, it results from
the activity of the  entire fore-brain.  Anatomically speaking, the
exercise of intellectual activity by every  part  of the  cortex
depends upon the uniform structure of all parts of the fore-brain,
which  makes  of each part  a  centre for inductive processes,  and
supplies to each part nerve-elements capable of perceiving and re-
taining "images."   This is  true also of individuality, the motives
of which are  to be sought in  the  most frequently repeated im-
pressions of every sort.   These impressions hold a causal relation
to one another, and by  means of nerve-arches establish a connec-
tion of causality between residual images'  as  motives for move-
ments,  and  certain definite motor-acts.  In  order to  be clearly
understood, I will begin by  explaning the simplest relations.
   Kussmaul has  shrewdly  remarked that certian perceptions
and  movements are common to the  foetus in utero ;  that the
foetus  feeds  itself,  as it were, by swallowing amniotic fluid,  and
that there may be  special motives,  such  as  the more-stimulating
taste of the fluid  after the occasional depletion into it of  the
allantois, which  induce swallowing.  Here, then, there are two al-
ternatives, the foetus swallows or does not swallow.  We are already
presupposing fcetal consciousness, which would exist, however, un-
der circumstances which give but little opportunity for perception.

   1 The reader will by this time have noticed that I have given several translations
for the German "Frinnerungsbild"; no one English term appears to me to be entirely
satisfactory.—S. 
Primary Individuality : Instinct.          169
   The new-born  infant  at  once  discovers signs by  which  it
distinguishes between one set of perceptions and another.   One
set  of perceptions helps it  to define the  circumference  of  its
own body, another set belongs to the world  beyond it.
   However obtuse this perception may be,  and though the child
may at first  not even be able to discriminate between the various
impressions  of space, it is certain that the perception of its own
body-circumference is established  very early  in childhood. Among
other signs  by which  it learns to distinguish between  impressions
received  from its body and from the outer world are these: Con-
tact of a strange finger with its own skin  excites but one tactile
sensation ; contact between two parts of its own body excites two
tactile sensations—one from the touching, and the  other from the
touched part (Wundt).   Furthermore, a number of strange audi-
tory sensations strikes the ears of  a child, but only the  sound of
its own voice is accompanied by muscular sensations ; and  so the
attendant muscular sensations help the child to discriminate be-
tween movements of its own body and any other forrn of  move-
ment which it may have occasion to see.   The number of such
examples could be increased  with  ease.   And, besides, it  is im-
portant to remember, that the continued presence  of  impressions
which its body yields—as,  for  example, the sight  of its own
hand, and the ever-increasing number of muscular sensations, due
to  movements of the hand, will  soon become fixed in its con-
sciousness, and that, by repetition, the intensity of such percep-
tions will soon  outweigh the interrupted occasional  impressions
received  from the  outer world.
    In the work of  registering images in the cortex, the memories
conveyed by those nerve fibres, which  enter into definitely asso-
ciated groups, and  constitute tracts along which a motor impulse is
most easily conducted, lend a helping hand ;  it is fair, therefore, to
expect that  frequent and simultaneous sensations, which emanate
from the body itself, will enter into  firm connections, which they
will  never again be able to dissolve, and which will thus form the
first primary conception  of the ego, based  upon the  perceptions
of the body's circumference.
   And here it will be proper to remark, that there is no order of
movements  which, under the cover of instinct, can be pushed in
between  conscious and reflex movements.  The first instinct of a
child would  be its  instinct for food ; but the origin  of that  has
been alluded to.   There is absolutely nothing in the sensation of 
170                     Psychiatry.
hunger which would acquaint the child with the means of remedy-
ing this pain, of initiating movements suited to this end.   It ob-
tains naught but the concept of pain.  In the general restlessness
it  displays,  and  in  the convulsions  ultimately  resulting from
anaemia, there is nothing which could be likened to an instinct for
food.   If the child is not left to depend upon its own resources,
but has a nipple put  into  its mouth,  then the sensation thus
excited starts  the reflex mechanism of sucking.
   The child has thus acquired the concept that the sensation of
satiation is  connected with  the act  of  sucking, and  these two
sensory memories are associated with the sensations of innerva-
tion aroused by the sucking-act, probably, also, with the scent of
its mother's breast.
   That the child should  suck at every finger, we may attribute
to a reflex mechanism ;  but  that  the  child  should suck in its
dreams, proves that the  act  of sucking has produced  images
which have been registered in the cortex. If a child looks for the
nipple by turning its head on its mother's breast, it  is not moved
by a reflex mechanism, and there is no  logical reason to suppose
that this is not a conscious movement, which is  based  upon  the
association  of painful  sensations and sensations of innervation,
both implanted upon  the fore-brain  by the  reflex mechanism,
which gave relief to the pain.  This would  be analogous to  the
conscious  closure of the  lids and  the  movements of  the arms,
instanced above.. There is no gap between conscious  and reflex
movements to be filled in by instinct.
   The factors of this primary, abstract ego are not definitely
defined.   No  child  is likely to lack the  sensation of  hunger;
but memories  collected from certain sensory spheres  may be
wanting in consequence of deafness, blindness,  or some other
defective perception ; and, in proportion to the lack of  perceptive
powers, there will be a corresponding defect in the sensory fac-
ulties of the ego; and yet  through  the more  intense applica-
tion (education) of the other senses (as has been  shown in the
case of deaf mutes who were blind also), an  extraordinary wealth
of images may be amassed, which can lead to an excellent knowl-
edge of the external  world.   Munk's views may help us to under-
stand the refinement and amazing development of  any one sense
which may do service, possibly,  for other defective senses.  Just
as single sensory spheres do not occupy the  entire  cortical area
connected with their special sensory nerves, but have a peripheral 
        The Cortex and Special Sense-Development.     i 71

zone which is left open for later occupation, so we can imagine, as
long as the cortical surface is practically one, through the  media-
tion of the gray network of fibres, that a greater area is left at the
disposal and for the development of any one sense ;  for a larger
area, generally  occupied by other sense-perceptions, is left func-
tionally vacant by the  occlusion of  its sources of  perception,
and through association-fibres this area  may be joined  to  the
only sensory spheres in active operation.
    Thus we  are  told by the  blind, that  from slight changes of
atmospheric pressure, the reflexes excited from the skin of the head
and extremities by currents of air give rise  to  innumerable  im-
pressions and inferences sufficient for them to perceive from these
sensations the presence of a large quiescent body in their vicinity,
and still better the presence  of moving objects.  The first  case
only is to the point; no doubt moving objects produce auditory
sensations as well.
    A  similarly exalted degree  of sensory  perceptions,  which
play a subordinate role in  the life of normal  man, is revealed by
the bat.  In Auteuriet/is Archives experiments are recorded which
have been performed on bats; their eyes were  destroyed, their
nostrils stopped   up  with  molten  sealing-wax, and their  ears
were also  effectually occluded.   But  though blind, deaf,   and
minus the sense  of smell, these  bats contrived  to  fly through a
regularly-constructed thread  network  without touching  any of
the threads. In accordance with the opinions then prevalent, it was
thought necessary in order to explain this phenomenon to  call up
a sixth sense, akin to that sense which  formed the basis of som-
nambulistic (?) perception.  If we  remember,  however,  that  the
bat possesses large wings, and very delicate, sensitive webs, which
present an enormous cutaneous surface, we need not be surprised
to  find that, as in the  blind, this  large sensitive surface enables
the bat to perceive changes in atmospheric pressure and  atmos-
pheric waves, created by bodies moving  about in  a direction
opposed to the current of  air.  From such changes the bat infers
the extent and direction of its movements.
    The nature of the  ego does  not depend  upon any definite
order of memories; it is determined simply by  the most firmly
fixed memories.   As soon as we apply the  test of  more com-
plicated relations to  the formation of the ego, we  must bear in
mind that the ego can be influenced only by images  of permanent
intensity, which are associated at the same time with other  and 
172
Psychiatry.
as firmly fixed images.  The idea of individuality is an artificial one,
though valuable from a practical point of view, for the degree of
intensity by which these images and their connections adhere to
this conception will not admit of accurate measurement;  and it is
plainly impossible to say that at a certain intensity a presentation
becomes a factor of the ego, and not yet at another.  There is but
one safe stand to take  on this question, and that is to attribute to
the ill-defined conception of individuality only those presentations
which, as soon as the " character" of  an  individual is known, will
enable us to predict his deeds; whence it follows that the deeds of
the individual obey certain laws.   On the other hand, these same
conscious deeds, as they are not mere copies of acts suggested by re-
flex movements, remain incomprehensible as long as the character
of the individual is unknown.  This very mystery attending the
deeds of others is another and highest expression for the  freedom
of the will.
   There can be little  doubt but that the primary order of move-
ments is  effected by  the diencephalon, the mesencephalon, and
other centres lying still  farther from the hemispheres; the first-
named ganglion contributing largely to the formation of the spinal-
cord columns, through the continuation of their bundles  through
the tegmentum of the crus.  But now the question arises,  whether
there are distinctly separated cortical centres, or nerve-tracts, which
mediate in  the  execution  of  secondary  movements—copies of
reflex movements—and  of  tertiary  movements, which bear the
stamp of individuality  ; both kinds of movements being distinctly
cortical in origin. Charcot contended that paralyses, resulting from
(lesser) lesions of the lenticular nucleus, were distinguished by their
shorter duration from those resulting from lesions of the crus, or of
such parts that spring  directly from the hemispheres through the
internal  capsule;  and that (complete)  destruction of  the crus
entails  permanent  paralysis.   But from the  study of  the ana-
tomical structure of these parts,  we  learned that a considerable
portion of the internal capsule and of the  pes  pedunculi  is inter-
woven with -peduncular  portions  of  the  lenticular  nucleus, with
the stratum intermedium.  It is evident, therefore, that destruction
of the pes pedunculi will also destroy tracts from the lenticular
nucleus.  It was absolutely necessary for the  lenticular fasciculi,
lying in front  of the  crus, to interweave  with  the  peduncular
fibres, in order to reach the substance of Soemmering, lying behind
the crus cerebri. 
             Conduction to and from Cerebellum.         i y\>

    Charcot's statement becomes intelligible only  by supposing
 that  the  gray substance of the spinal cord conducts  motor im-
 pulses after the interruption of the connection between the white
 anterior columns, inasmuch as all white bundles pass into the gray
 substance, and establish conducting tracts in the gray network of
 fibres, though the speed at which impulses are  conducted is very
 much reduced.   This  might  possibly hold  good for a moderate-
 sized lesion affecting the gray substance of the lenticular nucleus,
 and amends  might thus be made  for imperfect conduction ;  but
 lack  of gray substance precludes  the  possibility of such patch-
 work in that part of the crus  in which lenticular and cortical bun-
 dles of the crus are interwoven.  Lesion of the crus is, therefore,
 necessarily followed  by  impairment (annihilation) of lenticular
 conduction.   There is  one difference,  to  be  sure, between  the
 course  of the  stratum intermedium and the  pyramidal tracts,
 and that is that the cortical bundles of the latter develop into the
 anterior longitudinal fasciculi of the pons, and as  such, connect
 with the cerebellum.   The  possibility of a similar  connection
 between the  cerebellum and the stratum intermedium  cannot be
 absolutely denied, for the latter, instead of being crossed by the
 brachium  pontis,  might  possibly  interlace with  the superior
 division of the corpus restiforme.  And yet the  intimate union
 between peduncular and cerebellar fibres is the only one that  can
 be regarded  as  established beyond  controversy.  The  difference
 in regard to  the  function of the  pedunculus and  the  bundles of
 the stratum intermedium might become intelligible by assuming
 that the peduncular fibres co-operate with the  brachia pontis in
 effecting  complicated (more co-ordinated) movements, while  the
 lenticular nucleus constitutes a co-ordinating centre per se.  Ac-
 cordingly the  co-ordinations  of  movements conducted  by  the
 stratum intermedium would be effected in  the gray masses of  the
 fore-brain. But I am not willing as yet to  draw any positive con-
 clusions as to the importance  of one or the other of these tracts
 engaged in the transmission of motor-messages from the cortex.
   The occurrence of sling-shaped bundles in the  pons can be
 utilized to illustrate  the manner  in which the brachium  pontis
 endows the  cerebellum with a co-ordinating influence  over con-
scious motor-innervations (p. 115, et scq.; Figs. 43 and 44).
   These circular (sling-shaped) bundles, which  unite in the pons
with fibres from  the  crus, enter and terminate in the  brachium
pontis of the same side.  I can conceive that the one arc of this sling 
174                     Psychiatry.
constitutes a tract along which cortical motor impulses, passing
through the pes pedunculi, reach the cerebellum, and by  which
the cerebellum is  notified of the cortical sensations of innervation,
the work of association ; that,  on the other hand, the  other arc,
taking a recurrent course through the gray substance of the pons,
conducts to  the  pedunculus  cerebri  the  influence  of the cere-
bellum.  On page 28 it was demonstrated that the  dimension of
the pes pedunculi, the nerve-tract along which cortical  motor im-
pulses travel, varied  with the dimensions  of  the  fore-brain in
general,  and that  for this reason all  structures directly connected
with the pes pedunculi, such as the  pons and the pyramids, were
particularly well  developed in man.  We showed  also that the
alternating visibleness of the  olivary and  trapezoid  bodies in
man and animals  was determined by the  fundamental factor in
brain-trunk architecture—the  relative development  of the fore-
brain.  Were any animal able to increase the size of its fore-brain,
the basilar aspect of its trunk-structures would approach more
closely to the human " type."
   The stratum intermedium forms an integral part of the section
of the  anterior tract of the brain-trunk,  which  far exceeds, in
dimensions, the cross-section of the tegmentum. But the stratum
intermedium is derived from the lenticular nucleus, which  attains
its greatest development in man, and from the pes pedunculi, with
which it interlaces.   Consequently the development of this stra-
tum will keep step with the development of  the fore-brain, at least
as far as conducting nerve-tracts are concerned.    If appearances
deceive,  it is due to the presence in animals of larger quantities of
scattered gray connective tissue possessing no functional value.
   The  exact function  of the radiation  of the  posterior longi-
tudinal fasciculus  is still a matter of conjecture: its connections
with the nuclei of cerebral nerves, exhibited above with regard to
the third nucleus,  give undoubted evidence that it is  partly motor
in function ;  but, on the other hand, it  is connected also with
sensory tracts, those of the fifth and eighth nerve ; and possibly also
with the retina  through  the mediation  of the  basal ganglion of
the optic tract.
   Lesion of the lenticular nucleus produces hemiplegia ; and yet there is no connec-
tion between the fibres  of the anterior columns (descended from this  ganglion) and the
coordinating centre in the cerebellum save low down in the central gray substance, where
the bundles just mentioned unite with the pyramidal tracts.  There is no conscious
stimulus starting single complicated acts of cerebellar  coordination.  And then, too,
mere ataxia resulting from loss of cerebellar influence does not affect  the conscious in- 
The "Ego " and the Individuality.           i 75
nervation of uncomplicated movements ;  while clinical observation goes to show that
there need be but slight consciousness and hampered memory attending the distinctly
coordinated movements in the hypnotic state and in cases of chorea magna.   We may
argue, therefore, that during normal cerebral activity coordinated and conscious move-
ments are  tolerably distinct phenomena.   Since coordinated movements are no
criterion for the activity of  the lenticular nucleus, and since the initiation, direction,
and inhibition of a movement, which constitute its conscious features, remain intact as
long as the lenticular nucleus is preserved, and in spite of the presence of ataxia result-
ing from injury to the cerebellum, we must infer the only condition necessarily preceding
a consciously excited movement to be this, that t!:c lenticular nucleus be stimulate sim.-
ultaneously with the cerebral cortex. Moreover this very ganglion, forming together with
ihe nucleus caudatus, part of the gray substance of the fore-brain, stands in closer genetic
relation to the cortical substance than do the other (strictly speaking) sub-cortical ganglia.

    I return now to the  discussion  of the phenomena of  the ego
evolved by the cortex  cerebri  and  its medullary  mass; but  I
do not  intend  to  treat this  exhaustively  at present,  for we
shall have occasion to study  this  subject  more  fully in  the
clinical portion  of this work.  Let us suppose, in order  to give
a  concrete meaning  to the  term, that  there  be a primary ego,
a nucleus of the individuality, defined by the limits of the infant's
body.   And, as  a  rule,  the  image of  the  primary  ego will
coincide  with the  mental concept  of the  body;  there will be,
as  it were, a nucleus of  the individuality.  But the most fre-
quently repeated perceptions of the outer world, as well as the
most frequently revived memories, and particularly those joined
to  the  emotions, will enter into firm  associations, and will consti-
tute the nuclei of a secondary individuality.  Such memories will
be more readily reproduced, and will exert a greater psycho-motor
influence than transient impressions and less intense perceptions
will do.  And  yet the substance of  this secondary individuality lies
beyond the circumference of the body itself.  The entire  indi-
viduality becomes  decentralized and is made to  include  much of
the external world.
    The  primary ego expands  through  permanent  and  intense
secondary perceptions joined to  it by association; so  that in-
timately  related persons, property,  skill obtained by constant
practice in any  art, science, a fondly cherished aim in life, convic-
tions, patriotism, and  honor become part of  the ego.   That
from among these component  factors of the ego, the primary ego
should  be  consciously  endangered  by  surrendering  one's  own
body, can be explained by assuming that  component  factors  of
the secondary ego  have attained  such  a psycho-motor  intensity
in the play of association,  as to become  more effectual  motives 
176                      Psychiatry.
 than the original  powerful motive of self-preservation.  In fact,
 the very person who sacrifices his life believes, in so doing, that
 he preserves his own individuality, which  now  includes so much
 that lies beyond his physical self.  Whatever explanation one may
 choose to give of this phenomenon, the simplest will be this : In all
 the actions of  man, be they ever so complicated, problematic,
 or incomprehensible, the avoidance of greater pain is the  deter-
 mining motive.
    The  satiation  of hunger is  a powerful presentation  in  the
 infant's mind.   But if we  should attempt to put any thing which
 had been steeped  in acetic acid into the mouth of a starving child,
 the perception of  a momentary still greater pain would be joined
 to the sensation of hunger, and a reflex mechanism would be set
 in action which would prevent the swallowing  or retention of this
 noxious substance.   Whenever,  later on, a  substance that merely
 smells of acetic  acid  is brought  near it, the infant's mind, having
 already learned to utilize its registered  images and their associa-
 tions, as well as to start simple processes of thought which deter-
 mine the initiation of this or the other movement, the child will
 spit out, retch, cry, kick; it will consciously repeat repulsive move-
 ments which were originally reflex in character. These movements
 of repulsion are the direct opposite of those aggressive movements
 exemplified in the act of sucking, and in clinging to the mother's
 breast.   The child may associate the pleasure.of  satiation with
 the  swallowing of food, and yet  this so-called pleasurable sensa-
 tion will not be the determining motive for the child's  action;
 but as  long  as  it is exposed to two painful  sensations, that of
 hunger and of the pain produced  by a caustic substance—the
 choice of the lesser pain will be the determining motive.
    This discussion of the individuality has led us far astray from
 the consideration  of such  facts in regard to the architecture  of
 the fore-brain as are supplied by  a study of  its  anatomy, and such
 as are supplied by physiological experiments.
    A  more  definite observation of experimental  physiologists,
 though clad in vague language, is this :  They  maintain that loss
 of fore-brain entails loss of intelligence in  animals.  In order  to
 give tangible shape to this term " intelligence," I would say that
 under  the guidance of this  symbolic faculty,  only those associa-
 tions prevail  (from  among   the anatomically  possible associa-
 tions of registered images and  concepts)  which  represent the
ordinary regular connections of  things.   All parts of this organ 
             Methods of Thought, Associations.         177

of  intelligence are joined to each other by an evident anatomical
and functionally perfect association-tract.  The anatomy of  the
cerebral structure, and the proof of the presence everywhere in
the brain  of an  induction apparatus, render it  highly  probable
that all perceptions received simultaneously or in continuous suc-
cession become correlated with one another.  Such connections
explain the relations of successively and  separately received  im-
pressions to one another.  Our methods of thought and of speech
have designated this relation as one  of  causality; but this is a
purely  cerebral function, for there need be no bond in the outer
world corresponding to these  cerebral relations of causality;  nor
does this relation  constitute intelligence.  The  so-called  logical
sequence in the evolution of association, which yields the factors of
intelligence is effected in various ways and to a varying degree of
perfection in different brains.
    First the intensity of established associations, dependent upon
their conscious and  frequent  re-excitation, is of  greatest import-
ance.  An accidental succession of impressions is seldom repeated,
and relations thus established vanish quickly in  the brain. But,
as soon as the subjective bond of causality represents an actual
union of things, the re-occurrence of external stimuli will estab-
lish a permanent association within the brain.  Thus by the renewal
of  perception, such associations are turned  into the elements of
inductive logical thought.  Deduction  we  need not consider now
for it is the simple outcome of Induction.
    Secondly, a number of approved associations are transmitted
through the  medium of language,  through  conversation  and
instruction  from one individual  to  another.  According  to  the
degree  of  culture,  the intentions in transmission, and the logic of
those who communicate them, the mass of such transmissible asso-
ciations will be more or less remote from intelligence.  The imprint-
ing of prevalent associations by mere repetition upon the brain is
demonstrated also in  the negative phase of cerebral activity, in
the dissolution 1 of conscious associations.  It is  characteristic of
senile loss of memory, that  the  earliest  memories  are preserved
best, for these had been revived innumerable times in the processes
of thought during  more than half  a century, while the recent
associations, acquired shortly  before the  death of  the aged, can
have been recalled  but seldom to memory.   The loss of foreign
languages, following upon pathological  processes in the brain, does
1 Used in Jackson's sense.—S. 
i 78
Psychiatry.
not entail  ignorance of the  sounds common to the foreign and
the mother tongue, but includes only recently acquired knowledge
of languages.   The conclusion  is forced upon  us, that the indi-
viduality  also,  apart  from  its  relation to emotions—which in-
clude the  most frequently repeated associations,—is influenced
largely as regards the union of its component factors, and the diffi-
culty of disassociation by the more powerful bonds established
between the earliest factors of the individuality.
   If intelligence and individuality be  not  evolved  from per-
sonal associations of ideas, and  if the motives for the direction
of thought, and actions connected therewith, be simple copies of
psychical associations started in another's mind,  then the growth
of intelligence, as well as the expansion and  composition of  the
individuality, will be seriously impeded.
   As correlated sensations  of  sensory perceptions,  motor  im-
ages play a very important  role even  in the simplest processes
of the  fore-brain;  in  ordinary perceptions, such as  those of
space,  for  instance.   The perception  of space  is  by  no means
dependent  upon the  visual sense  alone, for  a  blind  person
has as full a knowledge  of the  surface  of  his  body as  one
with  normal  vision ' has.   Such  knowledge  is  enhanced  by
sensations  accompanying tactile  impressions received from  dif-
ferent parts of  the skin.  Thus  Lotze  has  shown how markedly
the  tactile sensation,  dispatched  from  the skin over the ster-
num, differs  from that  forwarded from the  skin  of  the thigh;
and  going  still  further into details, he  mentions the  different
tactile impressions received from  the  finger joints, and from the
more elastic and poorly supported skin between  the fingers ; from
the movability of the skin over the tendons, and its compressibility
between  the  tendons on the dorsum of the hand.  Lotze insists,
furthermore, on the great difference between the sensations accom-
panying compression of the volar surface of a finger against  the
nail—a perception influenced by the form of resistance presented
at both ends of the nail margin—and the touch of the nail itself.  He
refers also  to Spiess' remark, that the  local  signs  of  correlated
sensations  undergo further change through motion of the parts,
through  the varying  pressure  acting upon  joint  surfaces,  the
tension and relaxation of skin during flexion and extension,  and
through the contact between different skin areas.
   Correlated  sensations  play a very  important role,  in  the
endeavor to establish, through  the sense of touch alone, a skilful 
           Space-Image the Result of Induction.         i 79

and rapid recognition of all surface impressions from the body
itself.  To this  category of  sensations belong  the  sensations of
innervation in varying intensity, produced by contact of near and
distant parts of  the body's surface, and the sensations dependent
upon  the difference of the muscles  thus set in  action.   A  cor-
related  sensation  of  this  sort has  evidently  the value of  a
secondary (allied) presentation, for if any  part  of  the body be
touched  by a foreign body, we can, without putting  our own hand
to the part touched, be sure  of the location of this  point, simply
from  the local  signs which we  know from former  experience to
be associated with  certain sensations of innervation.   Projection
and association  are the two fore-brain principles at the bottom of
such  concerted  action, which  constitutes  an induction.  Funke
("Physiology,"  ii., p.  177)  has given a lucid exposition  of  our
judgments regarding the origin of sounds and noises in space.
Animals form a conclusion as to the origin  of a  sound by utilizing
the sensations  due to the reflex movements of the concha, and
other sensations produced by the  reflection of  sound-waves from
the convex or concave surface of the concha.
   Helmholtz and his pupil, Wundt, have given an explanation of
the retinal space-image, by showing the genetic  development of
space-perceptions, instead of adhering to the nativistic standpoint
of other authors; with the latter we are not concerned just now,
The manner in  which the retina  evolves  a space-image, which
is apperceived  by the  cortex, seems, at  first, easy enough to
explain ;  as  a  matter of fact, this  process  is quite  incomprehen-
sible.  It requires but  little  reflection to discover that a uniform
surface, which we are looking at, very soon evolves itself into a
mosaic  of smaller areas, or, at  all events,  appears  divisible  into
smaller  spaces;  and if, on the other hand, the most variegated
areas of  any surface be presented  to our eyes, we  should never-
theless  conclude  that they  were parts of  a continuous  surface.
Granted that every retinal fibre be  endowed with  a  special  per-
ceptive power for definite colors, and even for  definite shades of
such  colors,  this would not  suffice to produce a  space-image,
for one would be compelled  to suppose that these distinct local
peculiarities of  perception are  so distributed that the disposition
of variegated or uncolored portions of any surface would corre-
spond to the exact juxtaposition  of nerve-fibres of varying and
special sensibility—a view which no one will consider plausible.
   Supposing  the various points of a visible surface  to  be  pro- 
i8o
PsycJiiatry.
jccted upon different retinal cells, it would be possible to account
for the division of this surface into smaller areas, but it would be
difficult to form a concept of  these  smaller areas as a continuous
surface.  If, on  the  other hand, we assume the various parts of
the retina  to  be connected with  one  another, and that their re-
spective cells join in common  action, we can understand then how
conception of a  continuous  surface is engendered, but will  be
puzzled to explain the correlated concept of its divisibility into
smaller areas.  We  may, however, conclude that each single spot
of the retina receives its local  signs in  a different way, and we are
justified  in assuming  that the development  of a  retinal  space-
perception depends upon the association of innervation-sensations
of the ocular muscles and retinal impressions, just as in the develop-
ment of space-perception through the sense of touch sensations of
muscular innervation acted in unison with tactile sensations.  I
wish here to dwell upon Lotze's conception of the nature of local
signs, and I do this not with the intention of combating the views
of others, but because  by reason of their very simplicity, Lotze's .
views commend themselves to our purpose.
   It goes without  saying that the remarks previously made re-
garding the inadequateness of the retina to develop a space-percep-
tion, apply equally to the inadequateness of the cerebral cortex,
if the latter, in taking  cognizance of  space-perceptions,  is to
confine itself solely to  the adoption of projected retinal  images.
   The retina is composed of  two zones:  a smaller zone of distinct
vision—the macula lutea; and a larger one of indistinct division
—the horopter circle.   Distinct vision is accompanied  by move-
ments of the  bulbus, by  means of which definite points on the
horizon  are conveyed  to the region  of distinct  vision.   Thus
the visual act is attended by sensations of innervation, which are
projected upon the cortex, and result  from the  play of the ocular
muscles.  The projection-areas of the retina, and of the sensations
of innervation,  are  united  in the cortex cerebri by  association-
systems.   In the annexed drawing, the  projection of the retina
extends  from the bidbus through the optic nerve to a segment of
cortical surface,  corresponding to the region marked  I, 2, 3, on
the outside of the skull (Fig. 63).
   Three bright points,  I, 2, 3,  lying in front  of the bulbus,
fall upon different spots  of the retina, lying one above the other
(1, 2, 3.  The points are erroneously numbered, but this need not
interfere with our understanding of the diagram).   If these spots 
Space-Ids ion.
181
should lie above the macula lutea, it would be necessary, in order
to produce distinct  vision, to move  the macula lutea  so  far
upward that the  ray of light from  each  bright  point would,
in due rotation, fall upon the macula..  As an effect of the varying
intensity of its contractions, the inferior rectus muscle (J) will be
able to bring the macula  lutea into the  line of incidence of each
one of these bright  points.  A slight contraction of the inferior
rectus will cause the macula lutea to  change position with that
                             Fig.  63.
                           Space-Vision.
part which has been  irritated  by the  bright  point 3;  after a
stronger contraction, the retinal point 2 and the macula will have
exchanged places, and a still more powerful contraction will  ad-
vance  the  macula lutea  to  the portion  of  the  retinal  area,
upon which  the  point I had  been projected.   Through certain
fibres of the  tractus opticus, the points I, 2,  3  are represented
somewhere in the cortex, and in ancrther cortical region there is a
representation of that  branch of the third nerve which innervates
the inferior rectus muscle.   In the diagram one fibre is connected 
18 2                      Psych ia try.
with three cells, Jx J2 J3, and these three cells are joined to one
another  in the  net of gray fibres.   The^ contents of the  sense-
perceptions stored  in 3, 2, 1, in the cortex, are visual impressions;
of those lodged in J1 J3 J3, are sensations of muscular innervation.
There are certain resistances opposed to the conduction of nerve-
force in  this gray  network  of fibres, which in the  case of  the
nerve-tract leading to the  celta ] 1 J2 J3, as long as the intensity
of innervation is very slight, will excite but the one cell J T ;  if the
intensity be increased, there will be sufficient irradiation to involve
the cell J2 ;  and if the intensity of  innervation be increased still
more, the irradiation will  extend to all three cells—from which we
may infer that the signs J x J 3 J 3 correspond to different intensities
of innervation.   The least intensity  of variation results from the
effort to advance the macula lutea  to the  position  occupied by
the retinal spot  3 ;  a greater, from its attainment of the point 2 ;
and  the  greatest intensity will result when  the macula lutea has
usurped the position occupied by 1.   In  a succeeding portion of
this book we shall  have occasion to refer to the fact, that the in-
tensity of innervation attending emotions (Affectc), for instance,
is revived with the memory of this state.  The varying distances
between retinal  areas  and the macula lutea on every meridian or
parallel circle of the retinal hemisphere, are designated by  these
local signs of graded sensations of innervation, which are derived
from different muscles, according to the change in the position of
the macula lutea.   The sensation of innervation, which is joined to
the light-impression falling upon any spot  on  the retina, varies
according to the muscles employed and the innumerable gradations
of intensity.
   The perceptions of these sensations of  innervation and of  the
optic areas become associated in the cerebral cortex ; and by an in-
ference as to the retinal  spot, from  the nature  of the correlated
sensation inseparably  connected with it, every  retinal area  has
its proper  place  in the perception  of space.   In  this way,  the
topographical relation of retinal areas is registered in  the cor-
responding cortical region ; and  from this  relation we complete
the image of space. If I suppose the three bright points of  the
preceding figure to be stars, it may  be said that the retina per-
ceives space between the  three stars.   But we cannot suppose the
dark ether to be a retinal irritant; as far as perception is concerned,
it is  nil.   That  this nil between  the stars is  filled in by space,
proves that there is no direct perception  of space, but that  the 
Aggressive and Repulsive Movements.        183
latter constitutes a  subjective inference.  It is  not the vacant
ether which is actually measured, but the inference  made, aid-
ing in generating the idea of space, is based upon a measurement
of the distances between the three spots (stars) on the retina.  To
the extent that the visual concept of space is utilized by the sense
of touch, we shall find sensations of innervation derived from the
ocular muscles  associated  with similar sensations of  varying  in-
tensity  from the upper extremity.  The movement  of stretching
out the hand to seize objects lying at the side of us is accompanied
by sensations of innervation from the  sixth nerve, which directs
the eye outward.  If paresis of  this nerve  provokes a  stronger
sensation  of  innervation,  then   by  association more  forcible
movements of the hand will result, so  that the hand is extended
beyond the object it had intended to seize upon.
    This subjective power of the brain to evolve the idea of space
 from nothing, expands under pathological conditions to the power
of filling out space  with images which  are the creations  of  the
 brain—the outcome of cerebral irritation.
    To  this account of the widespread activity of the fore-brain,
 not only as the recipient, but  also as the creator, of sensations, I
 wish to add  that  it is  the boldest hypothesis,  shared  alike by
 the ordinary mind and by scientific realism, to  assume  that  the
 world  is such as it appears to the brain to be ; that the latter  can
 be likened to  a mirror which simply reflects the forms  of  the
 outer world ; that the world as it appears to the brain exists inde-
 pendently of the presence or absence of mind. Indeed, it seems to
 me to be a crucial test of an individual's  power of thought, to
 determine whether  he  can conceive  or not  of the  unreality of
 the world clad in forms which our minds have bestowed upon it.
 It should be reiterated that the idealistic conception of the world
 is supported by physiological facts, and still more positively by the
 facts of cerebral architecture before alluded to.
     Residual images would not  furnish adequate motives  for our
 movements and deeds if the phenomena of feeling were not inher-
 ent in them.   To the reflex of sucking we applied the term reflex
 of aggression ; to  that of vomiting,, reflex of rejection, of repul-
 sion.^ The conscious movements based on these reflexes  were
 termed  respectively movements of  aggression  and  repulsion.
 These resulted from association with  the ideas of satiation  and
  injury.  Such concepts were not mere passive reproductions of
  former images ; but their reproduction was attended by a degree of 
184
Psychiatry.
intensity which  we term  emotion.  In both cases the  emotion
varied, producing pleasure in the one case and pain in  the other.
A pleasurable emotion gives rise  to movements of aggression, a
painful  emotion to movements of repulsion.  Possibly we may
be better able to fathom the different degrees of emotion or feel-
ings by following a more complicated though physiological train
of thought  and  omitting psychological definitions  altogether.
Our understanding may be furthered by a series of  facts including
more than mere bodily pain and the reflex of repulsion ; for we
have to consider a movement accompanying the latter and affect-
ing the arteries of the central organ, and the connections of this
correlated movement with the change in chemical relations—phe-
nomena which are at the foundation of all nerve-phenomena.  It
will answer our present purpose to designate these chemical rela-
tions by the short expression : respiration of  nerve-cells.
   The solution of this problem would be reached by continuing
the line of  thought to which I have  hitherto  adhered,  and  by
proving that the  conjoined processes  above referred  to are  al-
ready associated in the cortex as secondary processes with others
involved in the mechanism of reviving associated images (or con.
cepts).
    Even though a decapitated frog respond to pinching of  his
skin with a kicking, repulsive movement, there is no need of sup-
posing  that a sensation of pain preceded this  act.  Nor are we
compelled to regard the conduction of the cutaneous irritant to the
muscles as the only process here set up, to which, if the brain had
not been removed, sensation would have been added.   We must
remember rather  that every sensory act produces a number of
secondary effects  acting upon the central  nervous organ ;  and
that such secondary effects, in default of fore-brain consciousness,
are nothing more than the  consequence of an irritation which
would be adequate to the excitation of pain.
   First.—The experiments of Schiff and others have taught us
that in animals in  which the conduction through  gray  substance
has been impaired, by experiment or otherwise, cutaneous irrita-
tion produces simply tactile or thermal sensations ; in spite of the
adequate  nature  of the  irritation  (burning) and the presence of
the fore-brain, there is no sensation of pain.  To this changed
condition  of  irritability we apply  the term  Analgesia.   We
know, furthermore, that nerve-conduction through  the network of
gray substance  meets with  a certain  resistance  which  can  be. 
Irradiation. —Inhibition.
185
gauged by the time which elapses in the transmission of a peripheral
impulse.  With an  increase in the number of  muscular groups
excited to action by a reflex irritant, an increase in the resistance
to nerve-conduction goes hand in hand.  The irradiation of any
irritation so as to  involve a large number of muscular groups, say
those of the side  opposite the cutaneous  irritation, will depend
upon the duration and intensity  of  the latter, and will  have an
influence upon the character of the pain-sensation resulting from
said irritation.   The sensation of pain, therefore, is attended both
by a reflex movement and by an inhibition of  nerve-conduction
in the gray substance of  the spinal cord.   The strength of the
resistance to  be overcome, in the case of motor irradiation, in-
creases, even in the ca-se of the unconscious, decapitated  frog,
with  the  duration and  intensity of the irritating  cause.   It is
evident, then, that inhibition, resulting from resistances introduced
in nerve-tracts, accompanies  the  simplest reflex processes,  while
consciousness in the main recognizes this inhibition as pain.  In
regard to inhibition, I wish to call attention to the  retardation in
the conduction of reflex nervous impulses.  A nervous impulse
takes, according to Helmholtz, about twelve times as long to
travel through the gray substance  as it does to be  transmitted
through the peripheral  nerves.   Transverse conduction largely
increases the time required for the reflex act, as when a  stimulus
applied to the one side  is to excite  the muscles of the other side
(Rosenthal, of Berlin).   According to Exner,  the  stronger the
stimuli, the less the amount  of time required to effect a  reflex
action.
    Secondly.—Irritation of  a sensory nerve excites in  decapi-
tated  animals not only a repulsive movement  of  the  skeleton
muscles, but exerts an  influence also over the  circular muscular
apparatus  of  blood-vessels, the centres for which are located  in
the spinal gray matter.   The ex-and in-tensity of this  influence
vary  directly  with the amount  of irradiation of  the  original
stimulant impulse.  The dilatation of the blood-vessels in the web
of a frog's foot continues steadily to increase as layer after  layer
of the spinal cord  is removed (Lister).  Goltz has  demonstrated
the functional activity of the spinal vaso-motor centres in mammals,
and W. Schlesinger (Strieker, Med. Jahrbiicher, 1879) has proved
their presence by experiments with strychnia.   We are  justified
in inferring that repulsive movement is attended by a reflex con-
traction of the spinal-cord arteries, similar to the one  which  takes 
186                     Psychiatry.
place in normal animals, and which is observed to result from an
increase of blood-pressure in the carotid after the application of
strong sensory stimuli.   The rise of blood-pressure in the carotid
following sensory stimulation was measured by Owsjannikow and
Ditmar with the use of the  manometer.   This increase of pres-
sure depends upon reflex contraction of the  arteries (vid. p.---).
In this way physical pain produces swooning, and explains why in
former centuries when a confession was extorted in court by tort-
ure, the person incriminated would fall asleep while  undergoing
the pangs of  the rack.   Ditmar believes that  there is no  better
proof of  the presence  of  sensory processes in animals  than the
rise of the blood column in  the manometer, following upon ex-
ternal stimulation, and that this increase of manometrical pressure
is caused by the reflex vaso-motor contraction set up  by the exci-
tation of sensory nerves.
    Thirdly.—The constriction of the arteries, by impeding the
respiration of  the nervous elements, must  necessarily engender a
dyspncetic phase  of  nutrition;  it  will  modify  the  chemical
changes going on in these elements, and as a further result of this
we  shall  find  the sensory stimulus  associated with the  irritation
resulting from a certain degree of dyspnoetic intoxication.  Dysp-
noea of tissues is alone  sufficient to excite repulsive movements.
Inspiration  is the most ordinary form of repulsive  movement
evoked by a dyspncetic stimulus, which in  extreme cases may, by
irradiation,  involve a  number of muscles.  But this dyspncetic
stimulus  results not only from defective breathing, but also from
increased arterial pressure, as in convulsions, or from arterial con-
traction,  as in anaemia.  The convulsions  occurring  in persons
bleeding  to death are an instance of the latter kind.  The respira-
tory centres extend,  according to  Procop  Rokitansky, into the
cervical portion of the spinal cord.
    From what has just been  said we may assert that  even in the
spinal cord of decapitated animals  movements  of repulsion are
connected with sensory excitation, inhibition of nerve-conduction,
increased arterial pressure, and  with dyspncetic  stimulation of
nerve-cells.
    Movements of aggression, also, can be demonstrated in animals
that have  forfeited the pros- and  di-encephalon,  and indeed in
animals which have retained  the spinal cord only.
    In his "Contributions to  the Study of the Functions  of the
Nerve-Centres of the Frog," Goltz remarks : " If on a fine summer's 
          Goltz s Croak-Experiment. —Aggression:      187

evening, we hear the croaking of the frogs, we conclude correctly
enough that these  inhabitants of the marshes are thoroughly
happy in the enjoyment of the tepid waters."  We  infer the
same cheerful  spirit, when  we observe  the playful  aggressive
movements of a cat engaged in pushing a ball or a mouse  before
it, and always endeavoring to recapture it; when we see animals
frolicking and tumbling about incessantly on the grass and in the
open air, or birds that give expression to their mirthful restlessness
by their song, and direct their aggressive movements upon crumbs,
seeds,  or worms.   All these convey the same impression to our
minds.   As soon as a stone is thrown into the pool the frogs cease
their croaking, in view of the danger to which they are exposed ; an
enemy suddenly appearing before animals that have been tumbling
about  in the full enjoyment of their liberty will cause them to
hide themselves,  or to  start movements  of repulsion by  taking
to flight.  The unhampered, purposeless movements of a lively
animal, the song of a bird, the merry bark of a dog,  are in  reality
movements of aggression.   Goltz has excited similar movements
of aggression in  decapitated animals, such movements indicat-
ing  a  certain self-consciousness, attended  by  undoubted  pleas-
urable sensations.    He  was  able to  elicit   the  croaking of
frogs and the aggressive movement of  clenching the female as in
the  sexual act.  The stimuli which  Goltz had to  apply in this
instance differed  materially in  character  from  those which elicit
repulsive movements.  The effective  stimuli were  of a  gentle
sensory and non-painful  character.   Gentle friction  between the
shoulder blades sufficed to provoke a  croak in  frogs deprived of
their fore-brains; and (slight) pressure brought to bear on, or fric-
tion of,  the  breast and flexor surfaces of the arms was followed
by an embrace of  any  thing  which  had  been  placed   within
reach of the arms.  The transmission of such gentle stimuli through
reflex  gray substance could not take place in the face  of any
great resistance, and, being permitted, it compels  us  to assume
the  existence of a  distinct  centre which is reached at once by
external stimuli.   The " centre," excited in the croak-experiment,
lies in  the mesencephalon, while the reflex centre  for the  sexual
embrace in male  frogs must be located in the cervical portion of
the  spinal cord.   The term "embracing spasm" (Umarmungs-
krampf)  will do justice to the powerful muscular action, resulting
probably from a hyperaesthesia of the frog's spinal cord, produced
during  heat by the nerves of the testicles,  but  existing  for 
i88
Psychiatry.
some  time after  the removal  of  the  testicles.   The  exciting
cutaneous stimulus need  be  merely  of  the slight  (unpainful)
intensity  mentioned above.
    Hence we may infer that even  in  the case of frogs that are
brainless  as  far  as consciousness is  concerned,  the correlated
effects (in the central  organ) of aggressive movements and  the
accompanying circumstances differ from those attending repulsive
movements, with which consciousness associates the  sensation of
pain.  These  two  orders of correlated  (secondary) effects are on
the whole diametrically opposed to one another.
    I.—The stimuli are  gentle and not painful; they must be con-
veyed to  certain  centres direct without irradiating and without
overcoming any resistance or inhibition.   In the  sexual spasm of
the  frog,  the conduction  of nerve-force was assisted,  and  not
inhibited, by a periodic increase in  the excitability of the centre.
Just as the consciousness of a  painful impression is  based upon,
or  is attended by,  inhibition of  nervous  impulses,  so the  con-
sciousness of  a  pleasurable  impression is  attended  by the free
transmission of nerve-force.
    II.—In the one case, the irradiation of a stimulus  adapted to
the excitation of pain, sets up activity in the centre for  the vaso-
constrictors followed by increased arterial pressure (active arterial
anaemia),  as  concomitants  of  repulsive movements;  and  in  the
other case, there is no  irradiation  produced by  external stimuli,
no inhibition,  and no increase in arterial pressure accompanying
aggressive movements.   Later on  I  shall  be  able to show  that
the movements of aggression are associated with a diminution of
blood-pressure, a dilatation of the arteries entailing the so-called
functional hyperaemia.  Ditmar's reflection, that increased arterial
pressure keeps step with the process of sensation, does  evidently
not apply to the generation of aggressive movements.
    III.—The  functional arterial dilatation necessarily  produces
an apncetic phase, in consequence of the increased  tissue-breathino-
of the nervous elements, and will bring about a chemical  change
also, differing  from the  one effected by a painful stimulus,  which
called forth a  dyspncetic phase of nutrition in these elements.
   These  antitheses are not artificial and far-fetched ; they are sug-
gested by the  fact that  in the reflex centres aggressive and repul-
sive movements  inhibit one another, because of the different pro-
cesses set  up by  the one order of movements or the other.  Goltz
has shown that the ordinary croak cannot be elicited,  if painful 
Inhibition of Repulsive Movements.          189
 stimuli be simultaneously applied; and that the sexual spasm will
 be inhibited if any part of the frog's body be at the same time
 touched with  acetic acid.  And, on the other hand, the  great ex-
 citability of the sexual spinal-cord centre  under  the influence of
 the testicle-nerves may, during  the period of heat,  inhibit the
 repulsive movements which would follow painful  stimuli,  were
 they not inflicted  during the sexual act.
    But have  we any  facts which will enable us to say whether
 the same accompaniment of vaso-motor innervation, of differences
 in the chemical  changes of  nutrition,  attends the  secondary
 mechanism  of conscious movements, incited  and set into action
 by subcortical reflex acts, which (movements) are based upon the
 revival of cortical  images, and are effected through the mediation
 of association-tracts; and  who will  say whether among the im-
 pulses of the Ego, and within the bounds of free will, we shall be
 able to discover and to discriminate between a series of  repulsive
 movements which had to  overcome a resistance  to nerve-conduc-
 tion, and aggressive movements which have had free pass through
 the nerve-tracts  engaged in their excitation or transmission ?
    Although  it has been shown (p. 141) that the  great expanse of
 cortical surface favors the restriction of certain functions to certain
»localities, it is certain that apart from the association through the
 arciform bundles,  and on  the supposition that its gray substance
 represents a network of  gray fibres, the condition of its structure
 permits the irradiation of  stronger stimuli, as is the case in the
 spinal  cord and  the remainder of the central  gray substance.
 Association and  Irradiation  are two  very  different  processes.
 We shall show that the process of irradiation  in the cortex inter-
 feres seriously with that of association.  As in the spinal cord so
 in the  cortex,  vaso-constrictor nerves  will be excited by an irradi-
 ating sensory  stimulus.   Among German authors, Eulenburg and
 Landois,1 as well as Hitzig, have shown that upon stimulation of
 the cortex the  extremities of the opposite side grow cooler (through
 arterial constriction), and upon removal  of the  cortex  the  tem-
 perature  of these parts increases (Hitzig) so markedly (through
 arterial dilatation) that  it can  be discerned  by  the hand placed
 upon the extremity of a dog so operated  upon, and without the
 corroborative evidence of a thermometer.2

    1 Centralblatt f. d. med. Wiss., 1S76.
    8 For full literature  vid. Exner : " Grosshirnrinde " ; Hermann : " Handbuch der
 Physiologie," Bd. II., p. 318. 
190                      Psychiatry.
   Let us take up the example discussed above (p. 184), in which
we supposed a brainless frog to  be exposed to an intense sensory
impression (pinching with forceps) and to display an inhibition
sufficient  to  overcome the stimulus.  We then discussed the in-
fluence of the stimulus upon the  vaso-motor  nerves, and the
repulsive  movements executed by motor nerves ; but let us vary
the example  by supposing an animal to be in full  possession of
its brain.
   A person who has been teazed with forceps, or who has under-
gone the  pangs of  an operation, will  recognize this intense irri-
tation as an impossible (unbearable) act of perception.  Evidently
irradiation meets with severe and widespread resistances in the
gray substance of the cortex as well  as in the central gray sub-
stance.  In this respect the pain answers to a sensation of inhibi-
tion.    The  inhibition, obstructing the path of this irradiating
stimulus, calls for an exhausting amount of excitation, and this
effects inhibition of other cortical functions, and sets a limit to the
activity of the  cortex ;  it inhibits  attention, thought, and the
association of ideas as well.   Secondary conscious movements of
repulsion  are incited (p. 184 et seq.) to ward  off the hands or in-
struments that have inflicted the  torture.  As concomitant con-
ditions, we get paleness, nausea, loss  of consciousness, together
with  slowness of pulse, with or without convulsions,  or uncon-
sciousness together with rapid pulse and universal convulsions.
   Loss of consciousness,  attended by nausea and slowness of
pulse, may be ascribed to  irradiation affecting the  vagus—the
cerebral nerve of the heart,—and to anaemia of the brain, due to
the suppression of the systole.  Though restricting myself to the
above-mentioned facts of experimental physiology as evidence of
the vaso-constrictor influence of  the stimulated cortex, and reserv-
ing other striking proofs of the fact (Kussmaul, Nothnagel) for the
clinical chapters of  this book, I have  said enough to infer  from
the importance of the cortex as  a vaso-motor centre, and from
the above-mentioned relation between  strong sensory impressions
and   an increase  of  blood-pressure,  that the  conduction  of
strong  sensory  stimuli  into consciousness  (into the  cortical
" gray ") increases the arterial pressure  and arterial constriction,
thus setting up active anaemia.  Whether this leads to actual un-
consciousness or not,  we may say that the sensation of pain is
associated with  increased  narrowing  of the  arteries.  But con-
traction of the arteries implies a chemical change, the dyspncetic 
     Actual Irritation not Necessary to Produce Pain.  191

phase of prosencephalic nutrition, and, united to the latter, the
disagreeable sensation of pain.  This  is the  less  hypothetical,
inasmuch as external chemical changes, such as accompany diffi-
culty of respiration in impure air, are attended by a sensation of
discomfort and restlessness, leading to repulsive movements, loss of
consciousness, even to swooning with  convulsions.   It has  been
shown,  therefore, that strong  sensory stimuli excite in  a reflex
way conscious movements of repulsion, and in originating sensa-
tions  of   pain  introduce  inhibition,  arterial  contraction, and
dyspnoea  of the elements of the fore-brain.
    It  is  not alone the perception  of actual pain  which incites
movements  of repulsion,  but the mere sight or touch  of, or a
sound from, objects which  are  associated  in the fore-brain with
the idea of pain, danger, or death,  excite, as the pain itself, move-
ments of  repulsion, and create in the cerebral cortex all  the con-
ditions of subjective torture  which we have learned to regard as
concomitants of real pain.  If the  mere sight of the sharp end of
a knife, of loaded fire-arms,  of  a wild  animal let loose, of a fire, a
corpse, an operation on others, or  the  sight of  blood, suffices to
produce loss of consciousness or swooning attended by the sensa-
tion  of  inhibition of thought, or impels the witness to take to
flight, we must suppose that our ideas  of pain are intimately con-
nected  with the revival  of  reminiscences   of these objects, and
that this  subjective pain is of sufficient intensity to  arouse all the
correlated physiological sensations accompanying genuine object-
ive pain:  namely, inhibition, increased  arterial pressure, dyspncetic
phase of nutrition, and repulsion.   Referring again  to the former
example  of the consequences of an  intense sensory  irritation
upon the spinal  cord,  we  observe  that the entire complicated
primary form of the reflex mechanism is transmitted secondarily to
the fore-brain.  The instances cited immediately above  referred
to  associations started by the actual perception of  objects calcu-
lated to produce pain ;  but  the momentary painful stimulus was
lacking.  Physiologically  speaking, the stimulus  bears  a special
characteristic sign, resulting from the excitation of peripheral sen-
sory nerves, and, more particularly from excitation of their terminal
apparatus ; among such  signs may be  classed cutaneous irritants,
dazzling  light,  unusually strong waves of  sound,  etc.  Pain  is
classified with  the  Feelings;  but it is  distinguished from sensory
perceptions by its  widespread  irradiation  which interferes with
localization. 
192
Psychiatry.
    Feelings without physical pain are termed emotions (Ergriffen-
heit).  We are here concerned with painful emotion, psychical pain.
That painful emotions depend solely upon associations, upon in-
ferences pointing to the perception of pain, can be proven by a sim-
ple analysis of the objects which excite pain.  The retinal images
of a tame and  of  a wild animal, of an indifferent person or of one
whom we fear, are projected upon the same retinal area, possess
the same color and  the  same  intensity of light.  An  indifferent
red fluid  and blood  leave the same  impression upon the  retina.
Mere  perception  itself cannot  excite emotion,  but the associa-
tions united to the former can.  It  is, therefore, the mechanism
of the hemispheres only—the process of thought—which excites
psychical pain  and movements of repulsion, as well as the arterial
contraction which may terminate in swooning, and in engendering
fear and a feeling of incapacity for action (Unmoglichkeitsgefuhl).
    But sensory impressions are  not needed to arouse the associa-
ions connected with emotions  ; recollection  of painful  impres-
sions may revive such associations.

    Boerhave relates a story in point : He says that he passed a spot where years ago
the smell from the cadaver of a horse made him vomit, and that the  mere recollection
of this occurrence produced nausea anew.  Without wishing to dilate upon such corrob-
orative evidence, we may add that reflexes attending painful emotions, such as crying,
may be excited by reminiscences, as is the case too with the centre for the contraction
of the blood-vessels. Further details about the connection between reflexes and emo-
tion may be called from Domrich : " Die psychischen Ziistande " Jena, 1849. Explana-
tions will be given later on.

    Equivalent  in value to  cortial  images  are  the symbols  of
language  associated  with  these.   The news of the  death of  a
person whose image would frequently be revived in our brain by
the most manifold associations,  and which when  presented to the
brain would arouse all sorts of  secondary presentations and pleas-
urable  emotions,  who was  bound up with  a good portion  of our
thoughts—such news, I repeat, would cause inhibition of all these
associations, and the place of  easily excited associations (through
repetition) will be  usurped  by others that are not  yet  easily
transmitted. Marked inhibition  of nervous impulses from the fore-
brain excites,likethe inhibited conduction of painful sensory stimuli,
or  the suggestion of torture, a concept of  the impossibility  of
counteracting this inhibition which may ultimately lead to suicide.
A physiological process occupying much time, and consisting in the
dissolution of now purposeless  associations and the formation of 
Processes of 7 bought and Their Relation to our Moods.  193

new ones, precedes the introduction of this death-news into the web
of associations.  Inhibition is attended by emotion and psychical
pain.  With inhibition and psychical pain there  is connected in-
crease of arterial pressure,  which during an emotion  may, by
mere presentation to the mind, produce swooning.  Inhibition or
resistances on the lines of nerve-conduction through the gray sub-
stance, as well as increased arterial pressure in  consequence of
strong sensory impressions, are physiological facts.
    Lastly, that the  impoverishment of the brain substance in
oxygen  (Hermann) has  the  effect of  a chemical irritant  which
excites dyspncetic respiration in the  oblongata, and produces epi-
leptic changes in the so-called convulsion-centre, is a well-established
physiological fact.  Since increased arterial  pressure even  in  the
cortex produces an impoverishment in oxygen, a dyspncetic phase
of nutrition  will be set up in the cortex as soon as the conditions
of painful sensations exist.   Sensation itself is the subjective
form of  perception of  all these physiological processes ; it is, as
it were, the  expression  of a  special sense concerned with  the
nutritive phases of the cortex.
    The stimuli and their effects, which interest us in this connec-
tion, may be  of every conceivable degree of strength.  The higher
intensities of Feeling may be termed  Passion, Emotion ; the lower
intensities, Moods, Temperament.
    By calling  the latter  hampered and  unhampered  moods, we
establish an evident analogy with the conditions which lead ulti-
mately either to repulsive or aggressive movements.
    If we are actuated by appropriate motives, the pursuance of a
complicated  process of  thought produces in us a  rapid change of
mood, according as this thought is hampered or furthered.   If a
beginner wishes to determine  the  rank of a plant in the natural
system, he must perceive  and associate in mind all  those character-
istics which have been united in such a way in his brain as residual
images, as to enable him to properly classify this  object in the
botanical system.  If he discovers a single characteristic which is
poorly developed, this cirumstance will inhibit the association ; if
he has forgotten the  proper term  for another characteristic, the
flow of association will be checked  also ; if still another quality of
this plant does not harmonize  with the others which  he thought
would suffice to determine its rank, further work in this direction
is hampered; and if he cannot  recall all the peculiarities of the
family to which he supposes the plant to belong, then the very 
194                     Psychiatry.
last step in the long process of association is rendered impossible
—no conclusion can be reached.  Confusion results, but confusion
indicates an inhibited association of ideas.  Displeasure is united
with this inhibition of thought;  the conception  of a  repulsive
movement to give up the plant or to throw it away will probably
follow very soon after.  The hampered mood will grow more in-
tense if the original motive was intense, say an examination in
botany on the morrow.  If  the associations had not been checked,
they would have formed a  complete circle, beginning with the in-
spection of the plant, taking in all possible associations on the way,
and ending by identifying the real plant with the one constructed
in the brain.  During the development of this process of thought;
the student would  have experienced a pleasurable sensation, and
a certain degree of happiness would have accompanied the attain-
ment of the conclusion reached through this chain of associations.
Every  scientific investigator who  endeavors to  work  out the
answer to certain problems, whether it be his aim to determine
the  correspondence  of  two cerebral   acts, say between  the
perception of a natural phenomenon and the conclusion reached
by a long line of association, in the course of which he endeavors
to evolve  the conditions  of this phenomenon in  such  a way
that they appear  as  the conclusion reached by his own  mental
activity ; or any one who  has successfully reached  his  Q. E. D.
experiences  a  psychical   happiness  even while  his  thoughts
are in  full blast.   This  sensation  (of  happiness) is no  doubt
to be ascribed to a determination of arterial blood to the busied
fore-brain, to  a functional  hyperaemia.   Functional hyperaemia
is the  physical concomitant of thought, and  in the succeeding
chapter we shall  endeavor  to  examine in  detail  the relation
between these two processes.  And the manner in which thought
in general produces  functional hyperaemia,  I  will  endeavor to
explain upon a physiological basis, and not merely by drawing an
analogy between the fore-brain and other brain-organs when in a
state of activity.
   Goltz explains the inhibition of the  croak-reflex  in the frog
through  painful constriction of one leg, by supposing the reflex
centres to form a single complicated apparatus ;   and having made
the assumption, he contends that  every  mechanism  will operate
the more easily, the  less  the tasks  it has simultaneously  to
perform.  The  croak-reflex  is inhibited by the  irradiation  of
another stimulus into the  confluent gray reflex centres. 
     Relation of Brain Nutrition to Mental Processes.   195

    The cerebral cortex has two distinct tasks to perform:   I.
 The innervation of processes of thought and of movements con-
 nected with these ;  2, the innervation of arterial vaso-constrictor
 muscles.  The more inactive  the brain is in the former respect,
 the more intense will be  the  constriction of the arteries.  This
 latter process will be inhibited  as soon as the first order of cortical
 activity is called into play;  which means that arterial constriction
 diminishes during the innervation of mental processes.   Hence a
 condition  of functional hyperaemia is set up.
    Although  different  sensory  stimuli   reach special  cortical
 areas, it was shown above that a revived memory, constituting the
 act of recognition, must be regarded as a complex phenomenon
 associated with secondary concepts, derived  from different areas
 of the cortex.  The majority of mental processes are based upon
 reminiscences or memories which have engaged the  functional
 activity of widely separated regions of the  cortex.   Whence it
 follows  that  the  functional  hyperaemia  will  invariably  affect
 circumscribed areas at  some  distance from one another; and
 this  is  equivalent  to  saying  that a  condition  approaching  a
 universal hyperaemia of  the fore-brain will be  established.
    A psychical condition, which engenders innumerable aggressive
 concepts, and puts no  obstacle in the way of the expansion  of
 associations, is attended  by  a feeling of happiness.   Winning the
 first prize in a lottery will make the ordinary mortal happy; this
 feeling of happiness is the result of an unrestricted flow of asso-
 ciations.  The wealth he has suddenly acquired puts a number of
 desirable objects within his reach ; with a number of objects his
 personality can now form associations which  could  formerly not
 be established from the  lack of wealth ; a multitude of possible
 aggressive acts present themselves  before his  mind ;  his  brain
 enters into a condition  of  great  though easy  and untiring ac-
 tivity, attended by an apncetic  phase of nutrition, thus standing
 in great  contrast  to the  check  put upon the  flow of associations
 through the loss of persons or possessions.
    We have seen that the concept of motion, the revival of sen-
 sations of innervation linked to a long chain  of associations, can
 arise in the mind unaccompanied  by movements or acts  of any
 sort.  We are, therefore, impelled to the conclusion that the execu-
 tion of  movements  demands  more  powerful  stimulation  and
 stronger nutritive stimuli.  The intensity of such motives for action
vary with the feelings.  It would be difficult  to conceive of the 
196
Psychiatry.
 existence of an  animal not actuated by feeling, and, indeed, to
 conceive of one that is not influenced by the two sorts of feeling,
 of which the one provides motives for movements of repulsion, and
 the other for movements of aggression.  An animal endowed only
 with  processes of aggression, and  lacking the conception  of re-
 pulsion,  or the power of performing  acts of  repulsion, would
 succumb to the  inimical influences of sensitive  and insensitive
 beings; while an animal that possessed no conception of aggres-
 sion,  nor the power to perform aggressive acts,  could not avail
 itself of the conditions of subsistence offered by nature.
   The phenomenon of (personal) freedom depending upon the
 variety of  possible deeds, is  best  exemplified by the  impulses
 which intensity of feeling imparts to our secondary individuality.
 Within the  realm  of  the primary ego,  the destruction of  one's
 own body—death—constitutes the  extreme concept of repulsion ;.
 yet through the  intensity of feelings,  joined  to the secondary
 ego, infliction  of  death may simply be an act  of repulsion by
which it  is  intended to ward off destruction from other portions
 of our individuality, as in sacrificing our own lives to save the life
 of a person  so dear to us that he has formed part  of our  own in-
dividuality.   Duty and  Honor have become integral parts of  the
individuality, exceeding in the intensity of repulsive and aggressive
acts  which  they arouse, the  factors of the primary  ego.   Com-
plications of the  individuality may reach such an extreme  that
the reflection of the individuality in the brain  of  others becomes
the leading  motive ; and the primary ego is sacrificed in order to
preserve an  image in  accord with our secondary individuality in
the brains  of the  survivors.   This constitutes  the desire for so-
called immortality.
   Let us   turn  now to the consideration of  the  anatomical
corollaries  and the results  of  the experimental investigation
regarding the subcortical ganglia,  which terminate cephalad in
the diencephalon.  The prosencephalic ganglion  may be looked
upon  as a nodal  mass among the centrifugal  nerve-tracts of  the
cortex ; its  conditions of excitation keep step with those of  the
cortex.  The relation  between the trunk ganglia, beginning with
the thalamus, and  the fore-brain is such that, although excitation of
the former produces sensory apperception in the cortex, the greater
the cortical excitation  following upon the independent revival
of cortical  memories and of  associations, and upon the exercise
of thought, the  more  the  influence of the subcortical  centres 
         Cortical Inhibition of Subcortical Ganglia.     197

 will be diminished.   This is cortical inhibition.   I wish  at this
 juncture to  call particular attention to the incommensurability
 of  cortical  reminiscences  with  sensory perceptions—a  fact  of
 great  importance in regard to all  future  discussions.  Sensory
 perceptions  are invariably  referred to the  external world, even
 in  those cases in which, through blindness or amputation, the
 peripheral sensory surfaces  have been  removed.  This is due to
 reasoning  by analogy.   By  experience we  have learned  that
, excitation of subcortical  nerve-tracts and  ganglia,  which trans-
 mit  sensory perceptions  to the   cortex,  is due,  in the  first
 instance,  to  a peripheral stimulus ;  and, therefore,  excitation of
 these  subcortical  tracts  and  ganglia is invariably referred, by
 the laws  of  causality, to  the external world.  It never occurs
 to  us, however, to suppose that the cortex is stimulated directly
 from the  external world ; whence it follows that cortical  images,
 which are due  chiefly to  excitation of the  cortex, can never be
 invested with the qualities of true sensory impressions.
    That the peculiar formation of the prosencephalic ganglion de-
 pended upon its important connections  with the anterior portions
 of the cortex was insisted upon on pp. 141 and  142 ; but although
 the nucleus caudatus and the  nucleus lenticularis  form  one
 mass,  their respective proportions are in striking contrast to one
 another.   It is safe to say that the intraventricular expansion  of
 the nucleus  caudatus does not vary much  in  its relation to the
 brain-trunk throughout the  mammalian  series.  In man its basi-
 lar  portion,  lying  above  the lamina cribrosa  anterior,  is  flat,
 while  in  animals with  highly developed  olfactory  lobes  it  is
 convex, and exceeds in size this  formation in the human brain.
 Excess of development in  this one particular is  evidently de-
 pendent upon the presence in  the basilar portion of the caudate
 nucleus of nerve-tracts coming from the olfactory lobes.   Magen-
 die was the  first  to  recognize the  corpus striatum  as an organ
 connected with locomotion, and Nothnagel  discovered in the cor-
 pus striatum of the rabbit a nodus cursorius, which, when excited,
 compelled the animal  to run  forward.   The  movements of ani-
 mals possessed of highly developed olfactory lobes are influenced
 chiefly by  olfactory impressions, for which reason we  can readily
 understand the connection between  these two physiological fac-
 tors and their relation to the structure of the nucleus caudatus.
    The lenticular nucleus is sparingly developed  in mammals,  in
 great  contrast to the development of this ganglion  in man and 
198
Psychiatry.
monkeys.  It is well developed also in the brains of the mole and
bat—whose anterior extremities subserve special forms of motion.
In  cases  of  hemiplegia, due to destruction of  the  lenticular
nucleus,  paralysis of  the upper extremity  exceeds in  intensity
that of the lower.  Climbing animals, including the monkey and
man, have from the very first  adapted their anterior extremities
to the performance of complicated movements, and  in  man  the
upper extremity  has  learned to do the bidding of psychical  im-
pulses ;  but man  and  monkey  are  the two forms which  are char-
acterized  by the  possession  of the most  highly developed nuclei
lenticular cs.  Quite recently three cases of  encephalitis  affecting
the right island of Reil have been reported, which were followed by
monoplegia affecting the  left upper extremity (Brodeur, Ray-
mond).   Severe paralysis cannot, as a rule, be attributed to lesions
of the cortex, and according to Munk the cortical area governing
the movements of  the  upper  extremity is  situated at a distance
from the island;  this monoplegia must  undoubtedly, therefore,
be  referred to  the lenticular nucleus which  stands in close con-
tiguity  with  the island  of P.eil.  Whence we conclude that in
addition to its well-known relations to the hypoglossal and facial
nerves, the lenticular  nucleus  has  special  relations to the move-
ments of  the upper extremity.
    The remaining masses of gray substance do not form  part of
the prosencephalon, but  lie within the walls  of the primary medul-
lary tube, which extends originally  only as far as the anterior
cerebral vesicle.
    The  relations  of the powerful   di-encephalic ganglia,  the
thalami optici,  have already been discussed (p. 162),  also their
prominent connections  with the optic tract.   Due attention was
bestowed upon the relations proved by physiological experiment
to exist between  the thalamus and the upper extremities, and thus
the influence of one thalamus—whose mechanism is set into activ-
ity by retinal impressions—upon different  muscular groups in both
arms was explained anatomically by the origin in the thalamus of
decussating and  non-decussating spinal-cord  tracts.  I wish to
add that the greater caudal  expansion of  the human thalamus,
exceeding as  it  does in this  respect the thalamus  of  all other
mammalian forms, may  possibly bear a  definite  relation  to the
greater use of  the upper extremities.
    The  anterior  ganglion of  the thalamus is not more  highly
developed in man than  in other mammals, and naturally enough, 
Relation of Thalamus to Visual and Muscular Senses.  199

-too ;  for there is an evident connection between this part and the
gyrus fornicatus, the cortical portion of which  Munk  connects
with  the sense of smell.   This conclusion is  borne out by its
connection  with the olfactory lobes,  and the  relatively  great
development of its substance.   From an anatomical point of view,
this anterior protuberance may also be considered a nucleus cauda-
tus.   The size of the human thalamus depends largely upon the
development of the pulvinar, which  arches over and beyond the
corpus  geniculatum externum, while in all mammals, with the
exception of the monkeys, the corpus geniculatum externum tends
upward toward the thalamus.   But on the other hand the corpora
quadrigemina are  less developed in man.   No  ganglion  has  as
broad connections on all sides with the cortex as the thalamus op-
ticus ; on superficial examination it appears to be connected with
the entire corona radiata.  And since this broad expanse of cortex
joined to the  thalamus is  connected with  almost  every cortical
function, we must infer that the thalamus has an important bear-
ing  upon functions of widely different character.
    The functional activity of an animal which has  not  been de-
prived of its thalamus, is in no wise  impaired, save that it lacks
 the  customary centrifugal  impulses  dependent upon cortical
 reminiscences.  There is good reason, therefore, to believe that
 all forms of sensibility are represented in the thalamus and cor-
pora quadrigemina.   In  corroboration of this belief we might cite
 the  very great influence sensory impressions exert upon  move-
 ments as long  as  the thalamus remains intact.   First  and fore-
 most we must  recognize the  projection of the  retina upon the
 optic  thalamus;   and  from  Nothnagel's pathological experi-
 ments we learn that  visual disorders  result  from  lesion  of the
posterior segment  of  the  thalamus—a  conclusion  which  is
in  perfect  accord  with  anatomical  facts.   As   long as the
 thalamus is  uninjured,  and  only  then, animals  are  able  to
 avoid  obstacles  thrust  in  their  way,  and  birds  that are
 thrown  up  in  the air show by their behavior that  they can
 measure  with  their  eyes  the  distance  to, and  the  direction
of, the ground upon which they are bound to land.  The posses-
sion of a thalamus enables an animal to creep  through  a narrow
opening between objects placed before it—a fact known even  in
 Magendie's day ; or, as Goltz observed in frogs, enables an  animal
to jump past  an  object placed  in its way, provided  there  be a
sufficient stimulus for escape.  Facial reflex movements seem also 
200
Psychiatry.
 to be  dependent upon the thalamus.   On  the one hand patho-
 logical cases are on record in which, in spite of an existing facial
 paralysis, the reflex movements involved in laughing, crying, in
 giving expression to  pain, and in the  protective closure of  the
 eyelids,  were well executed (Nothnagel, " Topische Diagn.  der
 Gehirnkrankheiten ") ; but in all such cases it has been remarked
 that the lesion did not affect either the thalamus or its medullary
 radiations.   And on the other hand Longet and Schiff have called
 attention to the grimaces of cats (which  have been deprived of
 their hemispheres) following the application of Tincture of colo-
 cynth to the tongue.  I do not mean to defend the term " psychi-
 cal reflex," nor to  insinuate that the projection which receives
 its innervation from the hemispheres (from consciousness) suffers
 an interruption in the thalamus ;  for of all negative physiological
 truths relating to the thalamus, there is none more certain than
 that  so-called  volitional  paralyses  are entirely independent of
 thalamic lesions ; and yet, if we do not wish  to give too simple an
 interpretation  to  facts of great  subtlety, we must keep  in  mind
 that the thalamus possesses a reflex mechanism  of such a high
 order, of such marked psychical characteristics, that Goltz, who is
 not satisfied with the term " reflex," would designate the complex
 functions of these higher physiological mechanisms of the  brain
 as " the  power of adaptation."   And then, too, the views I have
 expressed regarding the genesis of volitional  paralyses, which were
 implied  in the assertion that volitional movements are based upon
 the primary motor  images derived from reflex movements, must
 not be accepted as a negation of the fact that the co-ordinating
 power of  the  fore-brain  may  enable  it  to  exert an educational
 influence upon reflex actions.
    Lotze was no doubt justified in giving the  following  explana-
 tion  of  Pfliiger's so-called psychical  spinal-cord-functions:   He
 contends  that, in the young animal, movements of expediency,
■ like those of cortical motor acts, are not yet to be ascribed to
 the spinal cord, but that definite cerebral  co-ordinations, which
 are accustomed to utilize certain spinal nerve-tracts, leave an im-
 pression of  fore-brain activity  of such a nature that, after the
 removal of the brain, reflex innervation is directed  to the groups
 of nerve-tracts most  frequently engaged in the transmission of
 cerebral impulses.  Anatomically, this can be proved more readily
 for the spinal  cord  than  for the thalamus, for the  former is  con-
 nected with centrifugal cortical nerve-tracts, while the thalamus is 
Injluc7icc of Conscious-Movements upon Reflex Actions.  201

not so connected.  The thalamus itself is the centre for and origin
of the centrifugal tracts in the tegmentum of the crus ;  their in-
nervation is dependent  upon  stimulation  of the thalamus.  On
the strength of the discussion at the beginning of this chapter con-
cerning compulsory positions of the anterior extremities following
lesions of the thalamus, we conclude that the fibres radiating from
the cortex into the thalamus constitute  centripetal nerve-tracts
which conduct to the cortex the sensations of innervation created
by motor processes started in the thalamus.  We must necessarily,
however,  premise the  existence  of  centrifugal,  cortical  tracts
in  the  prosencephalic  ganglion and in  the  internal  capsule,
initiating the same forms of movement, and  emanating from the
same areas of the cortex, to which the thalamic radiations conveyed
the innervation-sensations  of such  movements.  Though the co-
ordinating fibres belonging to the cortex proper may refine  upon
and vary these  forms of movements, they  could not exert any in-
fluence  over the mechanism of the thalamus unless we assumed
the twofold conducting power of  cerebral nerve-fibres—a  power
which Dubois-Reymond proved that  the excised nerve possessed.
The association-tracts of  the  fore-brain possess beyond  a  doubt
such a twofold  power of conduction ;  for of two associated  corti-
cal reminiscences,  either one, when revived, will recall  the other.
I can find no grounds for denying a twofold nerve-conduction in
the thalamic projection-systems conveying sensations of innerva-
tion to the cortex ; and through these systems, movements which
have been modified  by cortical co-ordinations may react.   But
more  of this later on.   It was  in  regard to physiognomical ex-
pression, which is  not confined solely  to the facial  nerve, but is a
result of the activity of the muscular mechanism  of our entire body,
that Darwin asserted the apparently paradox principle that the
form of volitional movements in the ascendant are changed to reflex
movements  in  the descendant.  The inheritance of physiognomi-
cal expression I do not  consider proved.   At all  events Darwin
could have made  his views plausible only by showing that con-
scious movements originated  in reflex actions.   In that  event  a
reciprocal effect might be conceived ;  reflexes  might be proved
to be the primary  roots of  the simpler manifestations of the con-
scious motor mechanism ;  and later on the cortical co-ordination
might  generate more complicated forms of movement which,
from the presence of a twofold nerve-conduction, would  react
upon the motor functions of subcortical centres. 
202                     Psychiatry.
   The multiplicity of relations of the  thalamus as a centre of
automatic movements, and as such, its relations to the sensations
of innervation, its  bearing upon the sense of smell (restricted to
its anterior protuberance), and its relations to sight are in keep-
ing with the anatomy of this  ganglion as described  in the first
section  of  this book  (pp. 31, et seq., 48,  92,  101, 141,  and  142).
The  dependence of physiognomical expression upon cutaneous
sensibility leads  us to look for the anatomical  substrata of  such
expression  in the nerve-tracts of the thalamus.  At this juncture
it  is incumbent upon me  to fill in a gap in the anatomical de-
scription given above.   I wish to add that the fibres  of the  lem-
niscus, the  fillet, derived from the trunk ganglia, do  not issue
merely  from the  corpora  quadrigemina,  but that  some  of  its
bundles, situated to the front (cephalad) of the corpus bigeminum
superius (Figs. 55,  56, behind ss), and inseparable from  the inner-
most  bundles of  the  brachium  corp.  bigem.  inferius, originate
undoubtedly from  the thalamus.  In searching for the anatomical
substratum of the  possibly sensory functions of  the lemniscus, we
must  necessarily keep in mind the quadrigeminal origin  of the
fillet from  the brachium corp. bigem. sup.  Bundles of the lem-
niscus constitute the anterior portion of  the  brach. sup. (p.  102),
while the posterior margin  of the latter contains fibres connecting
the corpus geniculatum externum with the corpus quadrigeminum.
These bundles of the lemniscus stand in close contiguity with the
latter, centripetally conducting fasciculi  of a sensory organ, and
issue from  the same regions of the cortex in which are contained
optic  radiations, as well as the sensory bundles of  Tiirck which
pass through the internal capsule and the pes pedunculi.  There
is  no strict anatomical proof for the assumption that the occipital
lobe is the  chief central organ of sight ; but other radiating fibres
connected with this division of the cortex furnish ample proof, as
was stated at the  beginning  of this section (p. 142),  for the belief
that  it is connected with the special organ of touch (the skin).
Following the track of the  lemniscus into the spinal  cord, we find
that the fillet is  continued into the outer  portion of  the funiculus
lateralis (p. 134), which Mischer has  conclusively shown to con-
tain sensory tracts.
   The lemniscus, therefore,  connects the thalamus with the corp.
quadrigemina through tracts conveying reflex influences of tactile
stimuli.  The anatomical connection of the lemniscus with  the oli-
vary bodies-—from which the  posterior columns emanate (p. 134)— 
 Thalamus and  Corp. Quadrig. are Subcort.  Centres.   203

is also worthy of remark.  According to Renzi, detonation pro-
vokes movements of the eyes in frogs possessing normal thalami;
we must, therefore, suppose connections to exist with the sense of
hearing.   Remembering the entrance of  central auditory  tracts
from  the  cerebellum into the superior peduncles,  and on  the
other hand the connection proved by Wernicke to exist between
the thalamus  and the nucleus ruber of the sup. peduncle,—re-
membering these facts, we may say, although I wish to  speak
reservedly  regarding  the importance of  these  peduncles  as an
auditory chiasm, that  a connection of the thalamus with the laby-
rinth  is not beyond  the bounds of anatomical possibilities.  In
the oblongata the voice- and auditory-centres crowd upon each
other.   Possibly the motor function which Bechterew ascribes to
the thalamus in locating a centre for screaming in that ganglion,
and the " croak centre " which Goltz  locates in the region of the
mid-brain,  may  argue in favor of the  existence of  anatomical
connections between the VIII.  nerves and the  mechanism  of
articulation.   Since voice manifestations in animals represent the
acoustic factor in their physiognomy, we  might consider a phy-
siological  connection  established  between this function  of  the
thalamus and the above-mentioned function  of reflex mimical ex-
pression.  Possibly, also, the difference of opinion between Goltz
and Bechterew regarding  the voice-centre might be explained by
supposing that functionally at least the thalamus and mid-brain
are not strictly separable.
   Caudad of  the mesencephalon (mid-brain) begins the region of
the oblongata, which cannot be  separated easily from the pons,
and which, properly speaking,  does not  contain centres for loco-
motion, but for restricted movements only.   Goltz mentioned as
characteristic  of animals deprived of the mid-brain  and cerebel-
lum, in  contradistinction  to. those possessing a spinal  cord only,
that  the former could change  from the dorsal  to the abdominal
position.   Undoubtedly,  however, the pronounced  influence of
sensations upon bodily movements, such  as leads us to presup-
pose  a  centre (for the  maintenance) of equilibrium, is  to be
ascribed to the region of the'thalamus and mesencephalon.  The
possession of this centre enables a frog,  deprived of its fore-brain,
which had been  made  to squat  on the palm  of the hand,  to
change  its position step by step when the  hand is tilted  down-
ward, until it  is landed on the  dorsal surface.   To the di- and
mes-encephalon we  must, therefore, look for the subcortical sen- 
204                      Psychiatry.
sory centres, which help to perfect all possible movements of  the
highest order,  with the aid of impressions they receive, say, from
the retinal image  and the surface of the skin.  In the modifica-
tions here imposed upon the forms  of movement by retinal  im-
pressions, we  may recognize the  first  beginnings of the visual
impressions of space ;  though our fore-brain consciousness does
not take  cognizance of them until they have been  handled by the
mechanism of  association.
   The architecture of the corp. quadrig. (Figs. 38 and 39) showed
that tracts leading to it from the main external  terminal mass of
the  tractus opticus—the  corp.  genie, externum—through  the
posterior margin of the brach. corp.  quadr. superius, take a longi-
tudinal course in the mid-brain, thus avoiding a union with  the
formation of the lemniscus.  But these longitudinal  bundles are
united to the gray substance of  the  aquaeductus Sylvii in conse-
quence of a radiating course which they enter upon,  after taking
up quadrigeminal cells, and then traversing the layer of the lemnis-
cus.   In  this gray  substance the  nuclei governing the  movements
of ocular muscles are imbedded.  This allows us to conclude that
ocular movements  are stimulated by  retinal  impressions,  and that
this mechanism constitutes a simple  automatic apparatus.   Since
both the  gray substance  of the  corpora quadrigemina and  the
nerves supplying the ocular muscles are projected upon  the cere-
bral  cortex, a  union there  takes place  between the sensations of
innervation derived from the ocular muscles and the  impressions
of different retinal  areas, as was explained by Fig. 63, p. 181.   The
sensations of innervation of the ocular muscles, together with  the
projection of individual retinal areas, established  in the cortex the
local signs which help us to determine  our whereabouts in space.
Anatomical facts would go to prove  the truth of the  old view of
Wundt, now,  however, abandoned by him, that the  mechanism
producing the  psychical  conception  of space is started  into
activity by  reflex  processes.  The union of retinal  impressions
with muscular innervations in the corp. quadrigemina constitute,
in my opinion, the primary reflex process  assisting in  establishing
the conception of space.   The nature of this reflex process would
be similar to the one involved in the closure  of the  eyelids  fol-
lowing upon conjunctival irritation (p. 156,  and  Fig.  59).  When
analyzed into  its primary factors, this conception of space will be
seen to consist of sensory perception  and sensations of innervation
which have been secondarily transmitted  to the cortex.   To the 
Centres for Inter7ial and External Ocular Muscles.    205

entire  di- and mes-encephalon Eckhardt's remark is applicable :
that, " experience renders it highly probable that visual percep-
tions attain a certain degree of perfection in the thalamus."
   But we have further evidence to show that in addition, to  its
relation to the  centre of equilibrium governing locomotion—a
centre which  may possibly be  connected  with the  functional
mechanism of the corp. quadrigemina,—the thalamus exercises an
important  influence over the movements of the upper extremities,
as was demonstrated by the pathological case exhibited  in Figs. 61
and 62 ; and this will be corroborated by the observation of Noth-
nagel, that after destruction of the thalamus, the fore-limbs, which
had been extended, cannot be retracted.  This  is due to the loss
of the focus for the sensations of innervation engendered by the
movements of these limbs.
   The gray substance at the posterior margin of  the third ventricle
and around the aquaeductus Sylvii was investigated by Adamiick
and again by Hensen and Volckers. The latter contend that the cen-
tres for the intra- and  extra-ocular muscles succeed each other in
the following order : In the posterior portion of the gray substance
of the third ventricle  lies the centre of accommodation,  to the
front  (ventrad)  of  the centre for  the sphincter pupillae, both
centres being  connected with the most anterior  III. root.   At the
boundary between the  III. ventricle and the aquaeduct. we come
upon  the  centre  for the rectus  internus, and to the  outer side
from  this the  VI. centre.   At  the cephalic end of the floor of IV.
ventricle immediately below the corpora quadrigemina, the centre
for the vaso-motor fibres  of  the  iris is located,  which, in the
opinion of some, are solely responsible for the dilatation of the
pupil  by influencing the volume of the  pupillary tissue, while
others feel called upon to assume  the presence of a special dila-
tator pupillae.   However  this  may be, this region (containing the
above centre) lies  immediately adjacent  to  the general vaso-
motor centre  of  Owsjannikow, and, assuming irradiation to take
place, we may be able to explain the simultaneous occurrence  of
dilatation  of the iris and  of constriction of the arteries.
    Immediately below the gray floor we are confronted by the
descending arm of the formatio fasciculi long, posterioris. Wernicke
had  ample reason to trace   one   origin  of this latter system
to the lenticular nucleus;  the  projection-system  of  this  nu-
cleus would thus take a shorter route to the central  motor roots
and nuclei of the cranial  nerves scattered throughout the central 
2 06                      Psych ia try.
gray  substance.  The variable thickness  of  the posterior longi-
tudinal fasciculus, its connections with the  trigeminal and acoustic
tracts, preclude the thought that it is principally  the projection-
system for the motor nuclei  of the brain ;  its purpose  seems
rather to  be functionally to unite  different levels of the central
gray substance and to effect a co-ordination  of  movements.   It
may contain nerve-tracts uniting  the  abducens with the  topo-
graphically higher centres of co-ordination superintending the play
of the ocular muscles.  But the nerve-nuclei  of the  mesenceph-
alon, of the pons and of the oblongata are joined  by decussating
fibrae rectce to the  cortical bundles of the pes  pedunculi.  As was
exhibited in Fig. 43, et seq., these fibrae rectae, after traversing the
deep transverse fibres of the pons, extend to the anterior longitudi-
nal bundles and in the oblongata to the pyramids.
    The oblongata, which but for its cerebellar relations, need not
be  considered  apart  from  the pons, impresses  us with its  great
importance as a vaso-motor centre.  Owsjannikow has studied the
oblongata most carefully from this point  of  view.  This author
has demonstrated  that removing  layer upon layer of the brain-
trunk causes a fall of manometrical pressure, as  measured in the
carotid, even before the pons  has been reached, which  signifies
that that portion  of brain  substance has  been  destroyed which,
when normal, maintains the blood-vessels in  a  state of definite
contraction.   Blood-pressure  does  not  depend  altogether,  as
Bezold would have us believe, upon the  heart and  an increase of
cardiac innervation, but in an opposite direction, chiefly upon the
resistance which the contraction of the  fine capillary vessels op-
pose  to  the forward movement  of  the  blood.  Strieker  very
properly remarks that we are here  concerned not only with the
contractility  of the finer arteries, but also, as  has  lately  been
shown, with the smaller capillaries endowed with nerves, and even
with the more  delicate veins.  The blood-pressure ceases to fall
as soon as the sections have been laid within 3-4 mm. above the
apex of the calamus scriptorius. If the destruction by layers has not
transcended the level of the origin  of the facial nerve, the dimin-
ished blood-pressure can be restored  by irritating the sciatic, the
trigeminal, or the   auricularis magnus.   But from  this point on,
the possibility of restoring  the  blood-pressure by stimulation of
sensory nerves  sinks  until we reach  the before-mentioned lower
limit of the centre for the  vaso-constrictors.   Owsjannikow con-
sequently distinguished  between  two vaso-motor centres:  an 
          The Question of Vaso-Dilator  Centres.      207

automatic centre extending  farther cephalad, and a reflex centre
extending  farther caudad,  but for the most part  both centres
occupy the same level.
   He regarded the relations of these two kinds of centres to the
innervation of blood-vessels very much as I did that  existing be-
tween primary and secondary  movements  of skeletal muscles.
He insists that the automatic centre is subject to psychical influ-
ences, as is shown by the influence of the emotions on the dilata-
tion of blood-vessels ; and that the other is a  reflex centre for the
vaso-constrictors.  From an anatomical  point of view we  may
make the following distinction: the  one  centre innervated  from
the cortex belongs to the  anterior  division  of  the  brain-trunk
(pes pedunculi and stratum intermedium),  say, possibly to the re-
gion of the crus cerebri, and at all events  to the anterior division
of the pons ;  while the reflex centre is included in  the various
groups of cells which are interwoven  with  the posterior (tegmen-
tal)  segment  of  the pons and  oblongata.  Ditmar  thought the
reflex centre might possibly be located in the superior olivary body
of the oblongata.  The extension farther forward of the centre
governing psychical influences  can be  accounted for by the  fact
that the tegmentum begins to develop lower down  than do the
structures of  the pes  pedunculi  ; and the  termination of  this
cortico-vascular centre at a higher level would be sufficiently ex-
plained by the fact that the pyramidal tracts get rid of their gray
substance before reaching this level.
    Upon the  mooted  question  of vaso-dilator centres I will not
now  enter.  It  would  appear  as  though  they simply regulated
the antagonistic influences of the  circular  muscles, and exerted a
secondary influence upon the width  of the vessels ;  furthermore,
that a genuine dilatation resulted only from a lessened stimulation
of the vaso-constrictors.   It is, to say the least,  very significant
that  if they (the vaso-dilators) are  to be forced into action by
stimulation of the sciatic, the latter must have been cut across
several days previously, which compels us to assume that an  ante-
cedent condition of exhaustion  of the vaso-constrictors paves the
way for the subsequent preponderance of a vaso-dilator influence.
The known phenomena of dilation proper have reference to the
periphery—to cutaneous irritants.  Inasmuch as these phenomena
depend, according to  Vulpian, upon peripheral  ganglia, we  can
make no application of them to the  central  processes now under
discussion.  We take  no notice for the present of an active pro- 
208                     Psychiatry.

cess of vaso-dilation which has  been most  carefully investigated
by Goltz and  Strieker.
   The acoustic region occupies about  the middle  portion of
the oblongata (Fig. 17, p. 32).   Here our  morphological attain-
ments will stand us in  good  stead ;  for,  as Burdach puts it, the
structure and  significance of cerebral organs are united by a secret
bond.   The auditory nuclei are spread along the entire  line of
those central  motor masses from which the nerve-roots emanate,
and which are engaged  in the production  of sound, including the
facial, hypoglossal, and vago-accessory (laryngeal) nerves ; also the
respiratory and particularly the  expiration-centres, which play an
important role in this mechanism.   Thus we find the conditions
exceedingly favorable to the reflex origin of auditory  communi-
cations  ; we have given a focus which functionally contains  all
the elements of  speech, since  speech is based upon the repetition
of heard  sounds.  But this is not intended  to  be a teleological
conception of our organization.   Since sensory  stimuli irradiate
in the gray substance we must expect  stimulation even of the
lowest lumbar and  sacral  nerves  to irradiate  into other areas,
including the sound-producing  centre.   This is shown  in the re-
flex cry following in earliest childhood even, upon the traditional
educational handling of the skin over the  glutei.
   According to Pfltiger's laws,  particularly  favorable conditions
exist  for the translation of sensory stimuli into reflex movements
of a special character, if the  gray substance  in which  a sensory
nerve terminates, and  that from  which certain motor  nerves
originate, lie in adjacent levels of the cerebro-spinal axis.  Stimu-
lation of the  auditory nerve will, according to  Pfliiger's laws of
reflexes, excite most readily movements  of the  sound-producing
mechanism.   The primary fundamental  reflexes of speech are
based   upon  a   type  of structure as simple   as  that of  the
ordinary spinal-cord section ; upon centripetally and centrifugally
conducting roots of  gray  substance.   A sound  constitutes  an
auditory stimulus, and a sound results from the  excitation of this
sound-producing mechanism.    It is the  function of the motor
nerve-tracts engaged in  this process to effect a form of movement
which will  reproduce the contents of the  original stimulus which
was a sound.   This is  a purely imitative process.  Just as the
reflex-centre,  mediating between a conjunctival nerve and the
sphincter palpebrarum, transmitted  to the  cortex through the
cortical  projection-fibres a sensory stimulus and  sensations of  in- 
               Imitative Mechanism of Sound.           209

nervation, so, in the same way, the stimulating sound, the sensa-
tions of innervation derived from the muscles of this sound-pro-
ducing mechanism, and the  produced sound, are  associated with
one another in the  cortex.  Through  association, an  auditory
stimulus must consequently lead to the imitative mechanism in-
volved in the reproduction of sound.  For the secondary motor
mechanism  of  speech which goes on developing by  an endless
number of co-ordinating acts in the fore-brain, and for the methodi-
cal imitation of heard  syllables which is at the very root  of the
acquisition of language, there is a good  anatomical basis.   This
consists  in the presence of  a simple  reflex-centre which  effects
and permits a joint action  of the adjacent nuclei of VII., VIII.,
X., and XII. cerebral nerves with the  nerves of expiration.
   In the preceding section (p.  120 et seq.) I dwelt upon the con-
nection existing between the auditory fasciculi and the cerebellum.
Two  physiological facts  argue  in favor of such a connection :
the importance of the cerebellum as  an organ of motor co-ordi-
nation is a firmly established fact; and equally well founded is the
influence which auditory impressions exert upon the  rhythmical
evolution of co-ordinated movements in  walking, dancing, as well
as in the formation of notes in the rhythm of a song.   But there
is still another fact to be mentioned as corroborative of the above
anatomical connection.  According to all experiments, the nervus
vestibuli is  not auditory  in  function ;  but,  as Goltz,  Mach, and
Breuer, who repeated Flourens' sections  of the membranous semi-
circular canals of the labyrinth,  have been able to determine, it  is
responsible for the cerebellar maintenance of equilibrium.  De-
struction of these membranous canals  entails the forced move-
ments attending static vertigo.   Together with  Briicke, I regard
these movements as actions resulting from delusions  which pro-
duce abnormal sensations of  innervation, as I explained on p. 164
to be  the  case with regard to  the forced movements resulting
from lesions of the tegmentum and the optic thalamus.  Flourens
holds  that  similar forced  movements are produced whether the
semicircular canals  of  the labyrinth  or  certain  portions  of the
cerebellum be cut across.   He says :   " If the horizontal semicir-
cular canal be cut, the animal  will turn on  its  own axis ; if the
anterior, the  animal will perform a number of  somersaults for-
ward ; and  if  the posterior canal be cut,  the  somersaults will
be made backward.  Similar to  these movements are the rolling
movements observed after section of the pons, and the running 
210                      Psychiatry.
backward and forward following upon section, in the same direc-
tions as above, of the anterior and posterior pedunculi ccrebelli."
The direction of the movement  would invariably  be parallel to
the course of the fibres;  thus the rolling  movements subsequent
to lesion of the pons take place from one  side to  the other.
    Huschke, quoting Hamilton, communicates a fact which  has
an  important bearing upon cerebellar co-ordination.  It is this :
The cerebellum is far more developed in  animals which are able
to help themselves  immediately after birth (such as the chick,
pheasant, partridge, goat, colt)  than  in animals  which are born
blind, are helpless, and find  great difficulty in learning to walk.
In man the cerebellum is surprisingly undeveloped.  If the brain-
trunk be dissected out from the rest of the brain, as  in the manner
indicated in  Figs. 15-17, and if the cerebellum be removed also,
as shown in  Fig. 17, then we shall be able to determine the pro-
portional weights of three portions of the brain : (1) the brain-
mantle, (2) the  brain-nucleus from the  island to  the  beginning
of the spinal cord,  and (3)  the  cerebellum.   In  the adult these
parts  hold about the following relation,  79 : 10.5 :  10.5 ;  whereas
in the  brain  of  the new-born  the  proportions are,  83:11:5.
Magendie and Demoulins found long ago that injury to the cere-
bellum produces backward movements.   No  one at the present
day objects to the view that the cerebellum is  a way-station for
the muscular sense ; ataxic phenomena may, but actual paralyses
never do, result from  pathological  disturbance of this organ.
The muscular sense is based upon sensations which, when modi-
fied by disease of the cerebellum, give rise to numerous delusions,
such  as  falling  into a pit,  and so on.   We  must represent the
matter  to our minds somewhat as follows :  Those movements
which assume definite forms under the guiding  influence of the
cerebellum have their single acts associated with one another in
the fore-brain from childhood up; and the sensations of  innerva-
tions  grouped together in the cerebral cortex are  transmitted to
the cerebellum through centrifugal tracts—say, the pontine fibres
of  the  crus  cerebri.  The posterior  columns originating in the
cerebellum are  enabled  to  convey to that organ sensations regu-
lating the co-ordination of movements, making the intervention
of the cerebral cortex in the execution of movements quite super-
fluous.   Here the muscular sense comes into play in the manner
described by Spiess.  The varying sensations perceived  through
the posterior roots, changing with each phase of  a motor act, with 
                Co-ordination and Sensation.            2 11

the tension and relaxation of the skin on the extensor and flexor
surfaces  of the extremities,  with the  change in pressure due to
contact of different portions of the skin, are transmitted to the
cerebellum through the mediation of  the posterior columns; and
in the cerebellum, through the action of its association-system, are
utilized as sensations regulating the form of movements.  Taken in
this sense, the  gymnastic brain-organ  is also an organ of feeling.
Considering that the movements of the  eyes and the extremities
are accurately  co-ordinated,  as in taking aim  with a gun, we can
readily understand why cerebellar lesions should be followed by
deviations of the  ocular muscles, which would come under the
head  of forced  movements in the sense  in which the latter have
been  before referred to.   Even the simplest forms of movement
(such as changing from the dorsal to  the abdominal position, dis-
entangling the interlocked legs in the frog—Goltz) are performed
fairly well after removal of the mid-brain, as long as  the medulla
remains; but they are executed with greater  accuracy when the
cerebellum is uninjured, in which case sensation plays an impor-
tant role.  Some authors have proceeded still  further in  making
the cerebellum an organ of sensation.   Eckhardt mentions, in a
critical review  which he gives of the subject, that Foville observed
a general diminution of  sensibility following upon disease of the
cerebellum, that Renzi  found  that destruction of the cerebellum
entailed  impairment of  the visual  and auditory  senses, while
Lusanna noted visual destruction only  following a similar lesion.
    Among the remaining centres of  the oblongata the so-called
diabetes-centre is probably identical with the vasa-motor centre
for the  arteries of  the  liver, and  the  chemical results of the
diabetic puncture are dependent altogether upon the paralysis of
their  circular muscles.  In corroboration of this view, we may cite
the fact  that  if after paralysis of  the splanchnic  nerve,  which
exercises an all-powerful  influence over the blood-pressure in the
abdominal cavity, a general  hyperaemia  is  set up, there is not a
sufficient hyperaemia of  the liver to produce mellituria in  spite
of Bernard's diabetic  puncture.   Moreover, the oblongata is the
centre for a number of forms of movement, partly or wholly inde-
pendent of the will, which come within the domain of the nerve-
roots originating in the oblongata.  Closure of the lids, lachrymal
secretion, deglutition, constrictions of the pharynx, of the larynx,
and of the oesophagus, all  are dependent upon the oblongata.
Inasmuch as   the lower portion  of  the calamus  scriptorius  in- 
212
Psychiatry.
eludes the centres for in- and  ex-piration, it contains also the
centres for all  the modified forms of respiration, under the
influence of nerves starting from the oblongata such as'laughing,
crying, sighing, gaping, and sneezing.
   Of greater importance  is the  existence in the medulla of a
centre for the contractions  of the uterus and the vagina, which is
repeated,  however, in the lumbar   enlargement  of the  spinal
cord.   Goltz found that mammals whose spinal cord  had been cut
above the lumbar enlargement could still bear young.
   The influence  of  the  oblongata on the  salivary  secretion,
through the n. lingualis and the chorda tympani, as well as upon
the lachrymal secretion, depends  upon its significance as a vaso-
motor centre.  According  to the demands of an existing dysp-
noea  an  irradiation takes  place,  from  the mere  innervation of
the diaphragm such  as  is practised in ordinary breathing, to
an innervation of all respiratory muscles ; to the  extremities for
the purpose of fixing the thorax, to  the muscles  of mastication
for the purpose of " snatching " air.1  If  there be a  lack of oxygen
the oblongata becomes  a  general convulsive  centre;   and this
centre is situated, according to Nothnagel, between the lower por-
tion  of the pons  and upper portion of the  oblongata in man.
The  solitary bundle situated externally from  the  X. nuclei was
termed respiratory bundle by Kraus.
   Beyond a doubt the oblongata also contains in the tract of the
vagus a centre regulating the cardiac nerves.  Finally, we are told
that  a lesion of the oblongata along the auditory protuberance
produces derangement of hearing, and Renzi speaks  of a spatium
opticum extending  from  the corpora quadrigemina to above the
auditory protuberance, injury to  which causes  amblyopia.  In
regard to movements, most authors are  agreed not to attribute to
the oblongata the power of co-ordinating locomotion.
1 " Luftschnappen." 
      THE   NUTRITION  OF  THE  BRAIN.

   In the preceding section (pp. 138, 145) we contended  that in
order to understand  the functional  activity of  the  brain, it is
necessary to attribute  but  a single  transcendental quality, i. c,
sensitiveness, to the ganglion-cell and  its protoplasmic annexes.
From this faculty of sensitiveness actual sensation and its con-
comitant  or resultant  states, representing the functional activity
of the hemispheres, can be evolved, provided two  conditions be
met: there must be adequate nutrition of the ganglion-cell, and
peripheral stimuli.  As regards the latter, the external causes of
perception—the  stimuli—are  influenced by  the  peripheral end-
organs of  the  nerves.  The central  nerve-tracts,  which effect the
transformation of external stimulation  into sensation, were deter-
mined by anatomical and physiological methods in  the preceding
chapters of this book.
   On morphological grounds we reached the conclusion that the
brain was composed of two  grand divisions : the cortex with its
medullary substance—the brain-mantle ; and the brain-nucleus, en-
veloped by the brain-mantle, and consisting of subcortical centres
and  their  nerve-tracts.   We  remarked also that  association was
favored by the broad expansion  of the  cortex, while the possibili-
ties of irradiation were  increased by  the accumulation of the sub-
cortical form of gray substance in the ventricular cavities, and in
the walls of the medullary tube.  As regards the nutrition of the
brain,  the  ramification  of  the  arteries meets the requirements
of " association " and  "irradiation."  In my monograph on the
structure of the cerebral cortex (published in 1868),  I observed
that the broad expansion of pia, answering to the extensive sur-
face of the cortex, provided the latter with  the  largest possible
number of arterioles, all of about equal diameter, entering adja-
cent portions of brain-tissue, and of which each  one, represented
to a certain degree, an independent  circulatory area, and that  in
a mass of tissues supplied by a smaller number of  larger arterial
branches,  it would be  quite impossible for differences  of arterial
blood-supply to exist simultaneously in adjacent  portions of that
                               2'3 
214
Psychiatry.
tissue.  Whence it is to be inferred that the broad  expansion of
cortical surface, and  the large number  of arteries descending ver-
tically from the pia into the cortex, are well calculated to  permit
partial, functional  hyperaemia  of  separate  cortical areas.   This
peculiarity  in the distribution of nutritive  supply would allow
us  to suppose  that the so-called cortical  "centres" could  be
in a state  of functional  hyperaemia,  at a  time when  the  other
cortical regions  were enjoying a  functional  rest.   But we must
beware against ingenious exaggerations of  this theory of local-
ization.   I have  shown, when treating  of the  nature  of  re-
sidual  images  (p.  154),  that  in a  single  process of thought
widely  separated  areas  of  the cortex are  thrown into a state
of functional hyperaemia.  A detailed  analysis of the complexity
of  residual images (special  memories)  with  their manifold
cind widely distributed areas of functional hyperaemia, will lead
us  to accept an  opinion of Fechner, which  I  referred  to in
my monograph on the cortex.   The  excitation and nutrition of
the brain are subject to  a change between  two phases: one of
sleep, and the other  of waking.   Sleep implies a universal diminu-
tion  of activity,  but waking  by no means  implies increased
activity of  every part of the cortex.   Fechner looks upon  the
partially increased functional activity  of the hemispheres  in  the
condition  of wakefulness—that is upon the phenomenon  of  re-
stricted attention—  as a limited wakefulness, and accordingly  he
supposes  that  during the  state  of  cerebral activity  extensive
areas  of the cortex remain in a state comparable to  that of func-
tional repose.  Association as effected by  the hemispheres does
not therefore depend upon  the possibilities of a single  limited
area of functional hyperaemia, but upon the hyperaemia of numer-
ous cortical areas, united for combined simultaneous  action  by
the aid of association-fibres.   This end is furthered  by the pecu-
liar distribution of  arteries  derived  from the  pia.  The  multi-
plexity of  cerebral functions cannot be explained by comparing
the brain with any other organ whose physiological function is di-
vided equally among all its parts, and  of which  every portion  re-
ceives an equal supply of blood.  We can explain why every portion
of the spleen, of the liver, and of the lungs should receive an equal
amount of blood, but we can understand also, why, in regard to
the brain, all parts of which are never simultaneously active, the case
should be different.   The blood-supply in the brain is determined
by the functional hyperaemia  of  the areas  called  into activity; 
Local Hyper a mias in the Brain—Brain Movements.   215

while  in  the  case  of  other organs,  blood-pressure  and blood-
supply are  limited  only by  the  resistance of their  membranae
propriae, or their trabeculae of connective tissue.  In  the  physio-
logical  condition  the skull appears to  constitute a rigid  wall
limiting the quantity of blood in cerebral vessels, and controlling
any general  change that  may take place in this respect; by
reason of which it becomes an important factor in  the nutrition
of the brain.  A closer examination into the details of this  sub-
ject will convince us that the skull regulates the  pressure of the
fluid within its  cavity.  If the brain  were surrounded  merely
by rigid  cranial walls,  a  partial  change in the  distribution of
arterial blood would be conceivable.  Functional hyperaemia re-
sulting from arterial dilatation, set  up and regulated by the brain
itself, might be effected by a mechanism such as I have described
on p.  195, and would be  explained  by the fact  that the cortex
itself is a vaso-motor centre.   But within  the cranium with its
rigid walls a functional increase would be possible only upon one
of two conditions : there would have to be either collateral  arterial
diminution  (olygaemia), for which it would be difficult to suggest
an appropriate mechanism, or a transfer of venous blood in the
direction  of the sinuses, thus leaving more  room  for the play of
the  arteries.   But  this sort  of venous transfer  would be alto-
gether too slow; besides there could be no  continuous action, for
the repulsion of the venous current dependent upon the respiratory
movements, would  give rise  to a frequently interrupted  flow of
venous blood in the brain.   A different  explanation must be
attempted  for the  manifold  rapid  changes of functional hyper-
aemias, upon which depend cerebral excitation and  the effective-
ness of the mechanism of association.  We shall see, however,
that  the  brain  does  not  completely fill the  cranial  cavity,
but that the latter contains a number of  spaces, filled with so-
called  lymphatic  fluid.  The  skull is therfore  not per se the
cavity in  which the brain  rests, for on its basal side it contains a
number of lymph-cisterns (Key, Retzius, Schwalbe).  This explains
why the forms of the convolutions should be imprinted  upon the
concave walls of the roof, and not upon the basilary (sphenoid)
bone.  The base of  the brain would by its own weight rest upon
this bone, and would leave impressions of  its  form but for the
intervention of these water-cushions.   Nor  is the brain quiescent
within  the  cranial  cavity;  it  passes  through  three different
phases of  motion, as Burkhardt  was able to demonstrate  (in his 
2l6
Psychiatry.
monograph on the movements of the brain) on four patients with
defective skulls.   The movements of the brain in these four cases
were registered upon  a rotating cylinder, and  gave tracings:  (i)
of the systole and diastole  of  the  pulse, varying  between sixty
and eighty in the minute ;  (2)  of the expiratory rise  and the
inspiratory fall, numbering  from  fifteen to twenty in the  minute
(described before him by  Ecker);   (3) of the so-called  vascular
wave.  This  last is a peristaltic arterial movement, regulated  by
the vaso-motor centre, and occuring from two to six times per
minute.  These  forces, affecting the intercranial pressure and the
movements of the brain, are  equally active in a  normal closed
cranial cavity, but do not produce any compression of the cerebral
mass, for the lymphatic fluid,  the more movable contents of the
brain, recedes from or flows into  cranial spaces as the compress-
ing forces may demand.
   It will be necessary, first of all, to consider the anatomical and
physiological conditions  affecting the quantity of, and changes in,
cerebral blood-supply, and after that to discuss certain independent
cerebral influences, resulting from the activity of  the  brain itself,
in their relation to  the  distribution of blood ;  these influences
unite with the former conditions in spite of variations of  pressure
due to peripheral causes,' to perfect the nutrition and  function of
the brain.
   We shall find that these cisterns, which are of variable volumes
modify the cavity in which the brain is lodged, and that  there is
another mechanism by which  an  increase or decrease in  the  vol-
ume of the brain itself can be compensated.   This consists of the
venous spaces, described by Cruveilhier, adjoining the sinus longi-
tudinalis, which, like  the sinuses themselves, do not possess a wall
proper, but merely a simple limiting endothelium.   These venous
spaces represent, according to Langer, cavernous spaces  situated
between the  separated trabeculae of the tissue of the dura. Vari-
cosities of these venous spaces, by wearing away the vitrea, produce,
as Langer and Trollard have shown,  the foveae glandulares, in the
aged, in drunkards, and in subjects of cardiac disease.  These foveae
glandulares, be it said, are  not direct impressions  of the  Pacchio-
nian dilatations  of subarachnoidal spaces, to which we shall have
occasion to refer later on.  These cavernous spaces of  Langer,
Ludwig Meyer regards as a compensatory mechanism designed to
secure at all times the repletion of  the cranial cavity ; they dilate
as soon as  anaemia of the brain sets  in, and collapse with  the 
      The Subdural Lymph-Space and its Connections.  '217

return of a full  current of blood.  According to Schwalbe, the
arterial system of the skull and  brain  divides into two distinct
halves, according as the arteries are branches of the meningeal or
cerebral arteries.    The  ramifications lying  in the sulci arteriosi1
of the flat basilar bones are chiefly concerned with the nutrition
of the bone and the dura mater, or at least with that part of the
latter which  acts as  the periosteum of  the cranial bones, and
carries the blood-supply for  the  cranial  walls.   Besides investi-
gating the cavernous tissues adjoining the  sinuses,  Langer has
made a careful study of  the dural arteries, and divides these into
an outer  and  inner network.  The  outer network empties into
the capillary  net of  the dura,  and, which  is quite  remarkable,
empties at once into very large veins, which grow narrower as they
approach the finest arteries, while the inner network lying nearer
to the surface of the cranial cavity, and forming a derivative net
in contrast to the external nutritive one, does not divide up into
small capillaries, but  has  its arteries empty directly into veins,
thus  warding off to  a certain  extent the effects of hyperaemia
from  the nutritive vessels of the dura.   This observation of  Lan-
ger is of a kind with  the views of Schroder van  der Kolk, who,
as will be explicity stated later on, maintained that  there was a
direct communication between the larger  arteries and veins of the
pia on the surface of  the brain, having the effect, as he  puts it, of
allowing a strong current of arterial blood to pass over the  cere-
bral cortex directly into the veins, and permitting this vascular
storm, as it were, to  spend  its force  on the surface.   Heubner's
investigations have lent additional interest  to this view. It will
be shown that the increase and diminution of the volume of the
brain in  its  cavity, as Burckhardt demonstrated in his four  cases,
bear significantly upon the nutrition  of the brain, by transferring
the waste products to the lymph-vessels, for which reason it will
be  necessary  to  consider the relations between  the network of
blood-vessels  and the lymph-spaces of the brain.  The exfernal
(subdural) lymph-space has very different dimensions in  the spinal
and cranial cavities, for the spinal dura is widely separated  from
the arachnoid membrane, while in the case of the brain a  capil-
lary space is all that remains between the dura and arachnoid ; and
this capillary space is lined by endothelium, communicates  with
the  lymphatic glands of  the neck, furthermore  with  subdural
spaces which do  not immediately  surround the nerve-roots, but do

   1 Erroneously so-called (Langer), for each artery is accompanied by two veins. 
2l8
Psychiatry.
 so  in common with the arachnoid and are connected with  the
                                     i
 lymphatic spaces of peripheral nerves.   The  most important of
 these lymph-spaces, are those surrounding the auditory and optic
 nerves.  As regards the former,  it is  found that the peri-lym-
.phatic  fluid of the  labyrinth communicates with the subdural
 space.  It is equally plain that the venous spaces of the sinuses
 and their  surroundings communicate by a process  of transuda-
 tion  with  the  subdural spaces in the Pacchionian granulations.
 The  subdural space  is connected  also with the lymph-spaces in
 the tissue  of the  dura.  The arachnoid membrane, both surfaces
 of which are covered with an endothelium, shuts  off the subdural
 space.  This membrane envelops the brain, without forming any
 duplicatures upon it, but is  intimately connected  by means of a
 network of threads  and trabeculae of connective tissue, and on
 its basilar aspect by means of perforated membranes, with  the
 pia  which  covers every fold of  the cerebral  surface.   Henle
 speaks of this  network as physiological, hydropic connective  tis-
 sue, which permits a complete interchange between all subarach-
 noidal spaces.   These spaces are traversed at the  summit  of  the
 convolutions by tense threads, and are  narrower than over  the
 sulci.  On the  basilar surface in  particular, the  subarachnoidal
 spaces  are  dilated, and in  part  devoid  of  trabeculae.  This  ex-
 plains the  formation of cisterns (Key, Retzius Schwalbe).
    The following cisterns belong to  the surface  of  the  cortex :
 The  space of  the fossa Sylvii, which is merely  spanned by  the
 arachnoid, and a space which separates it from the dorsal surface
 of  the  corpus  callosum, which space  extends on  the basilar sur-
 face as far as the tinea terminalis (of  the central gray substance)
 situated beneath the corpus callosum.  More caudad on the basi-
 lar surface we come upon the cysterna chiasmatis and  the cystcrna
 intercruralis, the  latter dividing again into a superficial and deep
 reservoir.  From the cysterna intercruralis and to the outer side
 wide subarachnoidal  spaces extend  across the  crus cerebri  to
 the corpora quadrigemina, i. e., from the basilar surface  to  the
 dorsal  surface  of the trunk—the cysterna ambiens.   Short  tra-
 beculae unite  the subarachoidal  space  just over  the  corpora
 quadrigemina to  the surface of  the latter.  The  most extensive
 subarachnoidal  space on the dorsal  side is the cysterna magna
 cerebello-medularis, extending from the dorsal surface of the oblon-
 gata to the cerebellum, on the superior surface of which exactly the
 same relations obtain as over the convolutions of the cerebrum. 
Subarachnoidal Spaces—Pacchionian  Granulations.    219

   The pia  mater forms  the inner wall  of  the  subarachnoidal
spaces, of which the tche chorioideae, in the superior cerebral ven-
tricles, and in the fovea  rhomboidea, constitute a part.   This
connection, and the penetration of the pia into the ventricles, are
easily understood if we keep the fcetal brain (Fig.  1) in mind, and
remember that the pia covers every part of the brain-surface. At
the time when the hemispherical vesicle was situated to the front
of the anterior cerebral vesicle, the pia  mater  passed from the
former over  the latter to the mesencephalic vesicle.   But at a
later period, when  the hemispherical vesicles, enlarging caudad,
had enveloped the anterior cerebral vesicle, the pia mater of the
posterior surface of the vesicles  of the hemispheres was, by mere
flexion, made  to  lie upon the  pia which covers  the thalamic
region (derived from the anterior  cerebral vesicle).   Just as the
trabeculae  of  subarachnoidal spaces pass between  the dupli-
catures of the pia in the sulci  between two convolutions,  so the
two laminre of the pia •which accompany the  invagination of the
velum  chorioideum, are fastened  to one another by subarachnoidal
trabeculae.   Behind the corpora quadrigemina, the arachnoid of
the cysterna ambiens ascends  to  the upper wall  of the cysterna
corporis callosi.  The flexion  of the cerebellum over the oblongata
produces,  furthermore,  a  fold in  the pia on its way from the
cerebellum to the oblongata, the two laminae  of  this fold giving
rise  to the  tela chorioidca  of the IV. ventricle.  The foramen
Magendie leads through the pia from this ventricle into the sub-
arachnoidal space of the spinal canal.  In regard to the III. ven-
tricle, it  is to be remarked  that its membranous tela does not
correspond to the  superior wall  of the  primary cerebral vesicle,
but that the  only vestiges of this which remain are the epithelial
cells of the plexus  choroideus, at  the lateral margin and on the
inferior surface of the velum.
   The larger branches of the arteries on the  surface of the brain
do not lie within the  pia, but in the  subarachnoidal spaces; the
smaller branches only, enter  the pia.  Before  describing these, we
must  stop a  moment  to  note  those prolongations of the sub-
arachnoidal spaces, which are formed by the Pacchionian granula-
tions.  The latter occur in the course  of all sinuses, particularly,
however, alongside of the sinus longitudinalis.  The sinuses  and
the veins  adjacent to them  are situated in the substance of the
dura, and, according to Langer, are distributed in such a way that
the veins  of  the anterior portions of  the hemispheres meet with 
2 2 o                      Psych iatry \
the veins of the posterior lobes in the wall of  the sinus longitudi-
nalis, as  though the  former (veins) stood in the relation of vasa
vasorum  to the latter. a  The posterior cerebral veins take a similar
longitudinal  course  forward, between the layers of the dura, so
that the  cerebral veins empty into the sinus for a distance of only
2 cm., and about below the middle of  the  parietal vertex.  The
Pacchionian  formations push forward into  the cerebral veins as
diverticula of  the  subarachnoidal spaces.   The veins lie intra-
dural, and  the subarachnoidal  spaces are  shut  off  from  the
subdural space.  A definite brain-pressure,  which we  shall con-
sider hereafter, forces  the  subarachnoidal  serous fluid into the
subdural space, whence, by a process of filtration, it empties into
the veins and the sinuses.  The subarachnoidal spaces communi-
cate, moreover, with the lymph-channels  of  peripheral nerves,
which encircle the roots, as does the dura also.   From  these sub-
arachnoidal   spaces  we  can  throw  injecting   fluid   into  the
lymph-space  surrounding the optic nerve, into the perilymphatic
space of  the  labyrinth, and  the lymphatic  vessels of  the nasal
mucous membranes.  The pia cerebralis receives nerves from the
plexus  around the  circle of  Willis;  these  divide into  small
branches, which accompany arteries  of only I mm. in diameter
into  the  brain-substance.  Bochaldek  contends  that  branches
from the III., V., IX.,  and XI. cerebral nerves join these vaso-
motor nerves.   According  to Kolliker, the  plexuses do  not
possess nerves.  The sensitiveness of the dura in all experiments
proves that   it has sensory nerves ; they were demonstrated  by
Luschka and  Riidinger.  On the other hand, Nothnagel's experi-
ments, confirmed by Krauspe, show the relation existing between
the nerves of  the pia and arterial contraction, which is generally
reflex in  character.
   The arteries of the fore-brain are derived  from the carotid and
vertebral arteries.    The former supplies the art. cerebri ant. seu
corporis callosi (the anterior cerebral), and the art. cerebri media
seu fossa Sylvii (the middle cerebral).
   I. The anterior cerebral artery ramifies  on the orbital surface
over the  convolutions which surround the sulcus rectus and  the
olfactory lobe;  on  the external  surface,  over  a  wedge-shaped
region, which includes the second and  third longitudinal convo-
lutions (Fig.  9, L2,  L3,  cm., S.occ.) together  with the uppermost
portion of the central region as far as  the occipital lobe ; while on
the  median  surface,  the corpus callosum and the entire region 
Arterial Blood-supply : Heubner s and Duref s Views.  221

from the  frontal apex to the sulcus occipitalis receive their blood
from the  anterior, median, and posterior  internal arteries, all of
which are branches of the art. corp. callosi.
    II. The arteria fossae Sylvii embraces, with its ramifications, the
operculum and the superior temporal convolution ; and extends to
the  convexity of the  cortex, after sending off  several secondary
branches  for the  island of  Reil.  Charcot has  designated  the
principal  branch-arteries  as  follows:  1,  the  external  frontal
artery supplying the inferior  frontal  convolution; 2, the ascend-
ing frontal artery for the region of the anterior  central  convolu-
tion ; 3, the  ascending parietal artery for the posterior central
convolution  and the superior parietal lobule ; 4, a parietal artery
for the  region of the parietal convolutions; and, lastly, temporal
arteries  ramifying  over  the first and  second  temporal  con-
volutions.
    III. The terminal branch  (end-artery) of the vertebral artery
—the arteria profunda—supplies  the  cuneus, the gyrus lingualis,
the  gyrus fusiformis,  and the third  temporal  convolution, to-
gether  with  the uncus and the gyrus uncinatus.
    Both  Heubner  and  Duret deserve  great  credit  for  their
methods   of  studying  (by  injections)  the  details  pf  cere-
bral arterial  distribution ;  but there is  a great difference  of
opinion  between  these  two  authors regarding the significance
of the derivative arterial network of  the cerebral surface, which
unites with  veins  of   an equal calibre,'  as opposed to  the  nu-
trient network  of arteries,  which  connects with capillaries, and
from which  the end-arteries  of the  cortex  and  medullary  sub-
stance  of  the   fore-brain  are  derived.    Duret's  views  are
corroborated by Charcot.
    Heubner  does  not  consider  the circle  of  Willis  the final
channel for  effecting  a collateral  compensation of the  cortical
blood-current.  After passing  the  subarachnoidal spaces into  the
pia,  the cortical vessels issuing from the  circle  of Willis go on
ramifying until  the  minute branches  possess a diameter of but 1
mm.  These branches then break up into a net of arteries, commu-
nicating one with the other,  extending over the entire pia, each
part of which can be supplied  by one  of the chief arteries.   The
resistance among these derivative arteries is said to be so slight,
that it would be easier to inject the entire pia of one half of  the
fore-brain through one of the  six large  arteries, than to make a
1 As was known to Schroder van der Kolk. 
222
Psychiatry.
successful  capillary  injection of a  circumscribed region of the
brain.   From this common  reservoir issue the  more  delicate
arterial nets of the pia, and, at  right angles, the cortical arteries.
Even arteries of  the white substance, larger than the latter end-
arteries, which traverse the cortex without dividing, but are at a
greater distance from the injection-tube, can be injected more easily
than the vessels of the cortical network.  According to  Heubner,
therefore, the existence of this anastomosing net forbids our saying
that an artery supplies  this or that region or convolution, except
inasmuch as more distant arterial nets in the pia and cortex can-
not be as  easily  injected  from  one vessel as from  one another.
But these are differences which  it would be difficult accurately to
define.  In opposition to this  view, Duret held  that the super-
ficial anastomosing vessels have a diameter greater than I mm.,
and  that  the nutrient cortical  vessels are in reality capillaries,
as was maintained by Robin also.   In proof of this  Charcot and
Duret  refer to the  destruction of small cortical areas,  due to
embolism.   Whence it follows  that the arteries supply definite
nutritive areas, and  that  influences of the derivative network of
arteries is not as  powerful  as Heubner would have it.   Heubner,
however, quotes  in support of his views, cases in which embolism
of the pia-arteries  is  not followed  by softening of  any sort.
Charcot grants that there are such  cases, but he thinks them very
rare.   The  long  course  relatively  stout  arterial branches take
before dipping even into the wall of the longitudinal sinus, as
Langer has  observed, would  argue in favor of Heubner's  views.
Though the latter's opinion  regarding localized nutritive  areas
may be more unfavorable  to  the cortex than that of Duret and
Charcot, yet it is chiefly a question of difference in  the number
of cases of cortical softening due to embolism, which the various
authors have had occasion to  observe.
   On another point, however,  both authors are completely at
one—namely, as  regards  the  difference in the mode of arterial
blood-supply for  the cortex, and the subcortical masses which  for
the nonce include the prosencephalic ganglion.  None of the cere-
bral  arteries which unite with others to  form the circle  of  Willis
gives rise to larger arteries carrying blood to the subcortical organs,
and diminishing in size after undergoing  dichotomous  division ;
but these  subcortical masses are supplied with blood by a large
number of  arteries,  which issue from  the dorsal surface of the
circle of Willis, differ but slightly in calibre from one another, and 
The  Terminal Arteries of Subcortical  Ganglia.  223
resemble, in their  arrangement and number, the so-called lamina
cribrosoe  on  the   basilar  surface of   the  brain.    This sudden
diminution in calibre  of the art.  corp. call., of the art.  communic,
of  the art. foss. Sylv.,  of the art. prof., to a series of  vessels but
\-\\ mm. in diameter, departing  from  the main arteries at  right
angles,  and  penetrating at once  into  the base  of the cerebrum,
affects  about  2  cm.  of  the length  of  the  three  large cerebral
arteries  outside of the circle of Willis and the whole length of
the rami communicant cs.
    There are no anastomoses existing between the larger branches
of  this system of trunk-arteries ; and so these branches represent
what Cohnheim   termed  end-arteries,  none  of which  furnishes
anastomosing  branches before  dividing  up into capillary ramifi-
cations.   Inasmuch as there is no derivative  network beyond the
circle of  Willis, and as these arteries,  because of their shortness,
are under the more  immediate influence of  cardiac action, they
are more liable to hemorrhagic  rupture than  the cortical arteries
—a fact of great  importance in cerebral pathology.

     Following up the details of the distribution of arterial  blood-vessels to the brain-
trunk, we learn, according to Heubner, that the head of the  corpus striatum (the
nucleus caudatus),  together  with the  anterior wall of  the  infundibulum  and the
anterior portion of  the chiasma, is supplied ] by arteries coming directly from the art.
corp. callosi.; that the other portions of the caudate nucleus, together with the entire
 nucleus lenticularis and the anterior portion of  the  internal  capsule, receive  arteries
 from the trunk of the  art. foss. Sylv., which have passed through the foramina of the
 lamina perforata anterior ; while the ramus communicans post, is destined for the anterior
 tubercle  of  the optic thalamus, for the  posterior portions of the caudate nucleus, the
 posterior wall of the infundibulum, the posterior portion of the chiasma, the medullary
 bodies, the ant. tubercle, and the gray substance of  the third ventricle with its com-
 missure.    The area supplied by the arter. chorioidea would  include the environs of
 the cornu infer., whereas its choroid plexus would be distributed to the posterior
 division  of the internal capsule  and the outer half of the  anterior portion of the
 thalamus.  The art. profunda (2 cm. in length) supplies the posterior half of the thala-
 mus, the pes and tegmentum of  the crus cerebri, the corpora quadrigemina,  and the
 choroid plexus of the posterior horn and of the third ventricle.   The pons  and the
 medulla  receive small branches from the adjacent basilar, vertebral and anterior spinal
 arteries.   Heubner established these details of arterial distribution by showing that the
 (blue) injection-fluid thrown into the organ from definite portions of the basilar arteries
 would invariably extend to and through the same well-defined areas of the brain.
     The veins of  the brain run parallel to the brain arteries on the surface of the
 brain, and empty into the sinus falciformis.  The veins  coming from the vermis su-
 perior, and the vena magna Galeni empty into the sinus rectus.   Each one of the
 latter receives blood from an inferior vein  of the corp. callos.; from veins of  the cau-
 date nucleus, of the choroid plexus, of the optic thalamus,  and of a basilar  and pos-
1 Not regularly. 
224                     Psychiatry.
terior cerebral vein.   Rudinger found the sinus  transversi and the jugular veins wide
on the right and narrow on the left side in 71 cases ; in 27 out of 100 cases the reverse
"was true, and in only 2 cases were they equally wide on either side.  The broad sinus
transversus receives its blood only from the cerebral surface through the longitudinal
sinus ; through the sinus rectus the blood from the surfaces of the ventricles is carried
into the  narrow sinus transversus.
   No author has been as happy as Burckhardt in explaining the
general relations between  the membranes and blood-vessels of the
brain,  and their bearing upon  the  nutritive mechanism and the
vital  activity of' that organ.   Burckhardt's  conclusions, based
upon observation  of patients with defective skulls, were published
in' his  " Experimental Investigations  of Brain  Movements."
The pulse-wave, the respiratory and vascular waves were familiar
enough, as  they are common to blood-vessels  everywhere  in the
body.    The  respiratory waves,  indicating a  process  of venous
aspiration, point to one of the chief factors which determine the
flow of  venous blood  to the  heart.  The  movements of  the
arteries dependent upon the vaso-motor centre, and  indicated by
the so-called  vascular  wave of Mosso and Burckhardt, had  been
previously demonstrated on the ear by Schiff, on  the web  of the
frog's  foot,  on the curarized tongue of the frog, and on the saphe-
nous artery in the skin by Riegel, who gave a detailed account of
these movements  in a monograph on  the  influence of the nervous
system upon the circulation of the  blood.
   Riegel  insists  upon the  intensity of these peristaltic move-
ments of the  arteries  under  the  influence  of  the vaso-motor
centre causing  not  only capillaries, but  quite  broad arteries, to
contract to such  an extent as  only  to  permit the passage of a
single  column of  blood-corpuscles,  or indeed  temporarily  to oc-
clude  the arteries altogether.  The dependence  of this form of
movement  upon  a  vaso-motor centre  is proved for peripheral
arteries by  the  effect upon them of section of  the cervical spinal
cord.  Plering and others think it very probable that this form of
peristaltic movement is the result  of the respiration of the vaso-
motor centre itself,  but that the stimuli causing such contractions
have not accumulated  sufficiently to exert an influence with every
respiratory act; and that special influences from other sources,
acting upon the vaso-motor centre  through stimulation of sensory
nerves, disturb the rhythmic peristaltic movements of the arteries.
But  in the case of  the brain, the  fact that it is surrounded  by-
rigid cranial  walls,  by the subarachnoidal spaces, and that it  is
placed under considerable pressure,  modifies the effects of this 
            Trier otic and  Tricuspid Pulse-wave.        225

general vascular movement.  Since the membranes  surrounding
the  brain  enclose  spaces filled  with lymph and cerebro-spinal
fluid, these vascular  movements constitute an important factor
in the nutrition of the brain and in the exchange of metabolic
products.
   The  brain  is subjected  to considerable pressure.   This is
proved by the fact that from other organs tracings of  the pulse-
waves can be obtained only by placing the sphygmograph upon
the artery itself;  but, owing to the pressure it is under, the whole
mass of  the brain  is moved with such precision by the pulse-
waves, that accurate and distinct tracings  of a  tricrotic or tri-
cuspid pulse-wave are readily obtained by placing the pulsometer
upon the  mass of  the brain which happens to protrude from an
opening  in the skull.   The truthfulness of these graphic  tracings
is brought home to us by noting  that  tracings from the carotid
are exactly like  those representing  brain  movements;  though
the resemblance between the latter and the tracings  from more
distant arteries (say  the radial) is not quite as  striking.  The
details of  the pulse-wave  can be exhibited more clearly  with
Marey's  apparatus than with the rotating drum.
   As regards the radial pulse, Landois and  Wolff considered the
tricrotic  "s^^^/VA^JvN/ the normal form ; in this the  descending line
of the wave-like  tracing; due  to systolic contraction,  exhibits a
top-wave and two others traced nearer  to the period of diastolic
diminution.  Mosso,  on  the other hand, contended that the tri-
cuspid VVVYVYx  was the  normal form, showing in  its systolic
(ascending) lines a point in  front of the apex which corresponds
to the one on the diastolic side of the pulse-wave.   That the pulse-
waves are not represented by well-rounded  elevations and depres-
sions, must be  attributed to the sudden  influence  of arterial con-
traction  at the beginning of the diastole, causing  an acute angle
to be  formed between the ascending and descending lines; and
the two  elevations  following the  apex of the wave are explained
by the closure of  the semilunar  valves, and by the bounding
back of  the blood-column against the valves  (Mendel).   Both
act antagonistically to the depression which is due to the tonus
of the vaso-motor  centre, and which causes the rapid  fall of the
pulse-wave.
    If we increase the contraction of a radial artery by immersing
the  elbow in  cold  water, we observe  a distinct  tricrotic pulse;
if the other elbow be immersed in warm water, the arterial  walls 
226                      Psychiatry.
will relax, and the radial artery of this side  will give a distinct
tricuspid pulse.   In this case, the  arterial contraction is  so  weak
that the  first  leap  of the pulse-wave  does not prove to be the
highest of  the three, but the closure  of the valves  and the re-
bounding of the blood-current caiise the second elevation to rise
higher than the first, and the succeeding lower, pointed wave on
the diastolic side  of the pulse-wave dilates the artery to such an
extent that  the line reaches  the  level  from which  it was inade-
quately depressed through the influence of the vaso-motor centre.
Burckhardt  divides the cerebral vessels into subtentorial vessels in
the posterior cranial fossa, and  into basal  and  cortical vessels
which  are situated above the tentorium.   The former resemble,
as regards distribution,  the blood-vessels of other vascular  areas
of the body, and supply cerebellum, pons, and medulla oblongata.
The region  provided by the basilar and cortical vessels  includes
the ventricles.
   In order to understand the influence of the systole upon the
pulsatory movements of the brain, Burckhardt shows that the ar-
teries ascend for a long distance from the circle of Willis, and that
the venous  and  arterial currents take  the same  direction.  The
systolic enlargement of  the brain, in consequence of the engorge-
ment  of  the arterial network of vessels extending as far as the
capillaries and veins, begins at the  base of the brain  and  in-
creases in the direction toward the vertex.  This enlargement of
the brain increases gradatim in the direction of  the vascular  rami-
fications, so that at any one time all vessels at  an equal  distance
from  the circle of Willis are in  the same  phase  of pulsation.
The roof of  the skull  and   the  dural processes  offer a  direct
resistance to  the  swelling convolutions with their shallow sub-
arachnoidal  spaces; for which reason the brain  can  only en-
large  concentrically toward  the  ventricles.   In consequence of
the fact  that  the basal arterial  trunks and  the  long arterial
branches do not simultaneously fill with blood, the tumefaction of
the basal walls of  the ventricles diminishes at  a  time when the
swelling, brought about by the engorgement of the vascular net-
work  which is supplied by the higher arterial channels,  is begin-
ning, under the opposing pressure of the cranial roof,  to constrict
the ventricles, the force being exerted in  the direction from the
vertex.
   Since the basal and the dorsal  portions of  the  ventricles are
not simultaneously constricted, the pressure  is partially neutral- 
      Pulsatory  and Respiratory  Brain J lavements.   227

ized through  the  displacement of the cerebral fluid within the
cerebral  cavities.  The concentric swelling  of  the brain is very
nearly universal, since both the cortical and basal vascular ramifi-
cations tend toward the surface of the ventricles.   But since the
intraventricular dislodgment of cerebral fluid does not altogether
neutralize the arterial pressure, fluid  from  the ventricles passes
outward  through  the  foramen Magendie, while  the  concentric
pressure  continues to exert its influence upon the contents of the
ventricle, and, favored by the thinness of the  gray substance of
its  floor, spends its force on the  subjacent cystern. chiasm, and
intcrped., and, since  the cisterns are confluent, upon  all  the cis-
terns in general.   Through the pressure of the liquor cerebri the
pulsation is transmitted  to the  membrana obturatoria atlantis.
Still another portion of the systolic pressure which is responsible
for the increase in the volume of the brain is neutralized, through
the  circumstance  that the engorged parenchymatous  arteries
effect the exudation of lymphatic fluid from  those perivascular
spaces which lie  between  the  blood-vessels and the  adventitia,
the latter being prolongations  of the pia mater which accompany
these  vessels on  their course through  the  cortex  and white
substance.
    The respiratory  act produces  a fall of the pulse curve during
inspiration, and a  rise of  this curve during expiration (depression
and elevation of the pulse-wave).   This curve  depends  upon
the fluctuation of venous pressure.   The expiratory curve-eleva-
tion is due to the blood-stasis in the jugular vein, owing to the
insufficient aspiration of  blood from the  thorax, and  is increased
by the arterial blood-current, since  the pressure in  the  aorta
increases with the expiratory  pressure prevailing  in the thorax.
The influence of  the expiratory  wave is  noticeable in the cere-
bral curve,  even during quiet  respiration ; but  it is most marked
during violent expiratory acts, such as coughing and  screaming.
The  retrogressive stasis  acts directly upon the  rigid  walls of
the  sinuses, and  dislodges  at  once  the  venous  blood column.
The sinus  rectus is the shortest sinus.  Relatively to  the length
of  the  sinus, the  veins of the  choroid plexus  which empty
into  the  vena  magna,  are  the  longest.   The  stasis, which
starts  from the  torcular,  and is felt  first in the  sinus  longi-
tudinalis, and the sinus  rectus, with  the  exception of the  veins
of the subtentorial cerebral parts, will tell sooner upon the veins
of the cortex than upon the long, flexible veins of the ventricular 
228
Psychiatry.
plexus.   The  stasis will  also  aid in producing the concentric
swelling  of the  hemispheres, for  its  influence is felt last  of all
within the ventricle, and  is similar  to  the effects of the  pulsa-
tory wave, with  this difference, that  it  is felt from four  to six
times less frequently, and during  quiet respiration is less in
degree, than the influence of the pulsatory wave.  This concentric
tumefaction of the brain  again causes compression of  the liquor
ventriculi against the basal cisterns,  and its escape through the
foramen of Magendie, whence it follows that the respiratory curve
also will be noticeable at the membrana atlantis. The retrogressive
stasis in the  veins must  necessarily interfere with  the forward
movement of the lymphatic fluid, and thus prevent its transfer by
endosmosis into the blood-vessels.  The brain, which has become
enlarged by reason of this  stasis, presses against the cranial walls,
and exerts a  similar influence  upon the pressure in the direction
of the ventricles, as in the  case of the pulsatory wave ;  but there
is this distinction :  The  above  pressure acts from the  vertex
downward, instead of from the base upward.
    The vascular wave is  the  most  powerful, but the  least  fre-
quent ;  it gives from 2-6 tracings  per minute.  In height it may
exceed  the  pulse-wave, ranging from several  millimetres  to  1.5
cm.  The vascular wave causes a hemispherical protrusion  of the
cerebral mass, followed by a bowl-shaped retraction.  Height and
length of this wave are not equal. The  wave flattens  in  a cool
bath, and is raised in a warm bath.  Its lowest point (wave-depres-
sion) corresponds to the  contraction, and  its elevation  (wave-
summit) corresponds to the relaxation of the arteries.  It is most
distinct and regular during sleep;  during the hours of waking its
regularity is interfered with.  Moderately warm baths of 77-91° F.
lessen the number of waves, but make each wave longer ; warm
baths increase the number and shorten the  single  waves.  Es-
march's bandage diminishes, galvanization increases, their number.
According to Mosso the vascular wave is independent of the pulse
and respiratory waves.   But the vascular wave exerts  a decided
influence on  the  respiratory and pulse waves.
    During vascular contraction (wave-depression) the  pulsatory
waves are lower, for the artery is already contracted, but  during
relaxation they  are higher, more rounded, tricuspid  in  shape.
During the stage of vascular depression  the respiratory wave, too,
seems weak.
    All stimuli acting upon the sensorium  create vascular  move- 
      The Vascular Wave—Arterial Systole of Base.   229

 ments and  disturb the periodic  changes in the condition of the
 vessels.  Elevation is brought about chiefly by psychical influences,
 and less by purely intellectual processes than by emotions.  Burck-
 hardt had opportunity to observe in his patients the influence of
 pain due to panaritium ; the variations were marked, depression
 was persistent,  the  wave-length  occupied one  minute.   Sudden
 fright, produced by  an unexpected noise, caused a rapid rise in
 the curve, which was followed as quickly by a fall.   While one of
 his patients was busy playing at chess, low but long extended
 waves with  a few larger protuberances were noted.   One of them
 was quietly reading (to himself) a humorous tale ;  while thus
 engaged the  curve  showed  many  irregular  variations.   The
 pronounced vascular movement  in the ear of  the  rabbit is not
 noticeable  unless the animal be  frightened.  WJiile doing arith-
 metical  work—a purely intellectual function—elevations  were
 noted at the beginning and at the  end, in between depressions
 were more frequent.
    The vascular wave, an  arterial systole and diastole,  advances
 in peristaltic fashion.  Burckhardt appreciated the importance of
 this wave, constituting, as it does with  the aid of the rigid cranial
 walls, a motor-mechanism designed  to carry off waste  products
 through the lymphatic fluids by  establishing currents within the
 brain fluid.   To prove his views  he  refers  to Quinke's  cinnabar
 injections into  the  spinal  subarachnoidal  space.   The greater
 portion of the cinnabar penetrated as far as the  glandulae Pacchi-
 onicae, and also  into  the dura ; a  smaller portion passed  into the
 sheaths of the cerebral nerves and into  the cervical lymph-glands,
 but the injected substance did  not  reach  the  ventricles or the
 perivascular spaces.
   The arterial  systole, as was  the case with the pulse-wave, be-
 gins at the circle of Willis, constricts the base of the brain, pushes
 it  away from the floor of the cranium, and impels the blood for-
 ward  toward  the cranial  concavity, into  the  superior  arterial
 branches, which dilate because they have not yet experienced sys-
 tolic contraction.  The basilar constriction of the brain crowds the
 brain all the more against the cranial roof, and shuts off superiorly
 the advancing basilar liquor cerebri.   The systolic contraction of
 the base compels a portion of  the ventricular fluid to  escape
 through the foramen of Magendie.  The basal systole and  the
simultaneous collateral arterial  diastole in  the  upper portions of
the hemispheres, oppose the injection of cinnabar from  the ven- 
230                     Psychiatry.
tricles, for the roof of the ventricles is  compressed  by the con-
centric  swelling  of the upper hemispheres, which  are pressed
tightly against the  skull.   The pressure under which the ventricu-
lar fluid stands in  this first phase of the vascular systole, which
starts from the base of the brain, causes another portion of it (not
that which  escapes by the for. Magendie), through a current of
absorption,  to flow  into the veins of the choroid plexus.
    Thereupon follows the  second systolic phase—namely, the
systole of the superior cerebral arteries  which course along the
concavity of the skull.  The escaped ventricular fluid does not
now return from the subarachnoidal space into the ventricle,  for
the  basal collateral arterial diastole has set  in  simultaneously.
In consequence of  the swelling of the basal portion  the diastole
pushes the liquor past the  upper cerebral parts (which  have been
removed to a distance from the skull by the arterial systole) into
the Pacchionian bodies and the sinuses, and then  into the basilar
nerve-sheaths and  into the cervical glands.  The  foramen of Ma,
gendie lies  within the region of the basal vascular diastole, where
the swelling then present prevents  the entrance of the liquor cere-
bri spinalis, so that  a current moving in the direction of the spinal
canal keeps the injected cinnabar out of  the  ventricles.  During
the period  of  vascular systole  in  the hemisphere  the ventricle
itself is wide, for in the collapsed  state the hemispheres do not
crowd against the  concavity of the skull, and  do not present a
concentric swelling toward the ventricle.  The  choroid arteries
are in a  state of diastole  simultaneously with  the basal arterial
zone, and their dilatation produces secretion of ventricular  fluid,
the flow  of which resists the return of the fluid that was expelled
during the preceding  stage of vascular systole.
    It was stated above that Quinke's cinnabar injections did not
pass into the perivascular spaces between  the pia and media of the
arteries.   Burckhardt gives the following explanation for this phe-
nomenon :  If an artery, lying in the midst of a perivascular space
which communicates with  the subarachnoidal spaces, contract,
lymphatic  fluid will  pass  from the  parenchyma into the  peri-
vascular space (in a direction opposed to the course of the injec-
tion from the cerebral surface into the perivascular space), for the
passage to the subarachnoidal spaces on the convexity of the brain
is now unobstructed ; but  if this artery in the perivascular space
be dilated, it obstructs this passage  by filling out the above space,
and no,cinnabar will be allowed to enter the subarachnoidal spaces. 
         I'ascular  U\zve in Sleeping and Waking.      231

During this stage the lymph-current is impelled toward the veins,
as by  the pulse-wave, which,  with less  success during  cardiac
systole, enables parenchymatous lymph fluid to  be absorbed by
the veins, and during cardiac diastole opens up the passage  into
the subarachnoidal spaces.
   The lymph-current is opposed only during the stage of venous
stasis in  the  respiratory wave, which stage is accompanied by a
condition of cerebral  tumefaction.  This stage implies a constric-
tion of the perivascular lymph-spaces in the parenchyma, and the
advance of venous blood pressing in the opposite direction.   The
influence of this retrogressive stasis, however, is not to be rated
too high, for, according to Burckhardt, the influence of the  vas-
cular wave far exceeds that of the respiratory wave, and produces
greater variations in the quantity of blood.
   Knowing that the vascular movements of the brain are respon-
sible for the  circulation of lymphatic fluid in the  brain, we  may
infer from the regularity of  these  movements during sleep,  that
the refreshing influence of the latter is due not only to diminished
consumption,  but to a greater extent  to  the removal of waste
products.  On the other hand, the irregularities of vascular move-
ments  during waking indicate, as  Burckhardt puts it, that the
process described above can or must  possess a certain independence
in definite provinces of the brain, as is the  case with regard to the
(localized) reflex arterial constrictions on the surface of the body.
   Later on I will dwell upon the corollaries to be drawn from the
mode of vascular nutrition, both as regards the emotions, and  in
particular as regards the independence of functional hyperaemias,
as far  as  the  general vascular movements of the  fore-brain are
concerned.
   The  study of the  modes  of  cerebral nutrition  should be
followed by an examination into the chemical nature of the  sub-
stances and products of nutrition.  But on  this head  our knowl-
edge is far more fragmentary than it is in regard to the mechanism
of functional  tracts and the channels of nutrition.
   The reactions showing the chemical composition of the brain
can  be carried on  to a limited extent even  in microscopical in-
vestigation, thus enabling us to discriminate between chemical
substances belonging to the elements of the gray  and the white
substance respectively.  Other facts,  however, can be obtained
only by an examination of the entire masses of the brain ; and it is
difficult,  therefore, to make an absolute distinction between the
gray and the  white substance. 
232
Psychiatry.
    In  the  human brain the white substance constitutes the main
mass of the fore-brain,  while the gray  substance  is  the chief
ingredient of the brain-trunk.  In order to judge of the distribution
of the chemical bodies among the gray and the white substance, the
simplest procedure would be to determine the largest number of
elements in each, and to ascribe  the form which preponderates
in each case to  the gray or the white substance.  But such studies
have never been carried on with the aid of  my method of  dissecting
out  the  brain-trunk  and cerebellum  from the  hemispheres—a
method peculiarly adapted to such investigations (cf. Figs. 1.6  and
17).  Danilewski  is the only one who attempted  to  estimate  the
elements of the gray and  the white substance, basing the estimate
upon a comparison of the differences in specific gravity.  He found
that the sp. gr. of the gray substance  varied  between  1.029  and
1.038, and that  of the white substance between 1.039 anc^ x-°43-
He investigated also the  relative proportions of both substances in
the brain of man, and found that it possessed 37.7 to 39 per cent.
of gray substance, and 61 to 62.3  per cent, of white substance -
while in the dog the  gray and the  white substances are present in
the proportion of 50: 50.
   It was shown above that the preponderance of gray  substance
in animals as compared with the gray substance in man,  depended
by no  means upon  the  greater  number of nerve-elements,  but
upon the excess of amorphous connective tissue  in animals.   As
regards the latter, we know that it is not, like other connective
tissue, to be placed in the category of glutin-substances, but that
this non-nervous substance is also albuminous in character.  Boll,
nevertheless, considers it allied  to  connective  tissue, for, as
he claims,  all connective tissue contains  remnants of albumin,
derived from formative cells,  and this non-nervous gray  substance
is  simply distinguished   from other  connective  tissue by  the
possession of a greater quantity of albumin.  A very small quan-
tity  of amorphous connective tissue is, by the way, to  be found,
too,  in  the medullary substance of the fore-brain.
   And as for  the nerve-cells, of which the axis-cylinders of  the
entire nervous system are a uniform part, Kuhne has already shown
that both the nerve cells and the axis-cylinders give the reaction
for albumin.  This is based upon the reaction of the  axis-cylinder
with acetic and very  dilute nitric acid, concentrated and  diluted
alkalies, in which  the axis-cylinder swells and partly dissolves ■  and
upon the contraction and yellowish discoloration of the axis-cylin- 
              Nerve-Cells and Axis-Cylinders.           233

der in hot nitric acid ; and, furthermore, according to Rumpf,
upon  the characteristic reaction of the axis-cylinders of peripheral
nerves,  which  are  stained  red by  Millon's fluid.  Among the
various  kinds of albumin, it was formerly supposed  to  consist
of myosin,  and  then again to be identical with  the contents
in muscular  fibres ; but that  is disproved  by its insolubility  in
a ten-per-cent.  solution of sodium chloride.  From the  investi-
gations  of Kundt, and the  digestion experiments of Kuhne, and
Ewald, who used trypsin—the  pancreas ferment,—we now know
that the axis-cylinder is surrounded by a  sheath, containing indi-
gestible  keratoid substances.   These  keratoid substances are
contained in  a lime-yielding substance of the axis-cylinder sheath,
similar  to  Schwann's sheath,   which  surrounds  the  peripheral
nerves.  Accordingly, the medullary sheaths of peripheral nerves,
as well as the sheaths of the axis-cylinders in nerves and in central
medullary fibres, which lack Schwann's sheath, are horny forma-
tions, and those parts only which remain after the whole has been
subjected  to  the digestion process deserve  to be called keratoid
sheaths.   Rumpf demonstrated the axis-cylinder sheath by ex-
tracting the medullary substance of  the nerves  with alcohol and
ether, and removing it with chloroform ; or else by adding distilled
water, which expels  the  medullary  substance, causes  it to foam
and  to  divide up into globules of  myelin.  The expulsion  of
nerve-marrow by water can be explained on  mechanical principles
by the synchronous swelling of the axis-cylinder, which dissolves
slowly in water, and pushes its  horny sheath against the external
sheath of Schwann, thus  crowding out the white substance be-
tween the two.
   The chemical nature  of the nuclei of the ganglion-cells was
revealed through Jaksch, who  proved  the  presence of Mischer's
nuclein  in  the gray  substance  of the  brain ; while  Geoghegan
showed that  it was  present in the proportion of  1.4 to every
1,000 parts of the entire cerebral mass.  Although Jaksch did not
thoroughly isolate the gray  substance, he was able to prove the
excess of nuclein in the gray substance  relatively to the white.
   The presence of albumin and nuclein in the gray substance im-
plies the presence of phosphorus in the ganglion  cells and the axis-
cylinders.   Meyer and Cornwinder  proved that  in  plants, the
quantity of  phosphorus  increased  in  direct proportion to the
quantity of nitrogen, and Bischoff calculated that  the urine of starv-
ing animals contained phosphoric acid in definite proportion to the 
234
Psychiatry.
quantity of nitrogen—say,  I : 6.4 ; while if an animal be  properly
fed, the quantity of phosphorus and nitrogen taken in with the
food is greater than that in the excretions.  From these facts Voigt
infers that the albuminates and phosphates unite, so that we must
classify the fundamental connective tissue, as well  as  the  nerve-
cells in the  gray substance of the  brain, with  those  substances
which  contain phosphorus.    Direct  chemical  proof has  been
proffered of the high  percentage of phosphorus in nuclein; and
the quantity of nuclein varies in all  the organs of the  body with
the number  of  cells and  nuclei  which  they  contain.  Kossel
showed that the liver  and spleen yield  more nuclein than muscle,
which contains a lesser number of nuclei; that leucaemic blood
with its wealth of cell-nuclei contains more nuclein than the blood
corpuscles, .which  are devoid  of nuclei.   But, in the  second in-
stance,  the quantity of  nuclein depends  upon  the reproductive
power of cells in which  the  division of the nuclei plays so im-
portant a role ; so it happens that the  percentage of phosphorus
is higher in fcetal muscles and other foetal organs than in the fully
developed muscles ; and  the same  obtains  in plants 'with regard
to the momentary foci of growth.   The phosphorus of nuclein is
attached to an albuminoid body which can be readily isolated by
chemical means, because of its power of resisting digestive agents.
   The preceding remarks apply to the phosphorous elements of
the gray substance, which constitute an important  factor in the
chemical composition of the  entire brain.   Relying  upon  ash-
analyses and the investigations which Schlossberger, Bibra, Pollak,
and Jarisch have made on the various tissues of  the body, a fresh
brain  contains 0.49 per  cent.,  phosphoric acid  in  its gray  sub-
stance, and 0.89 per cent, in its white substance, while the  calf's
muscles  contain  0.48 per  cent., woman's  milk 0.38  per  cent.,
human blood 0.10 per cent.  The egg-yolk alone exceeds all, con-
taining  1.15 per cent, phosphoric acid.  In  the  brain of the dog,
which, by the way, contains less white  substance than the human
brain, Forster found 0.83 per cent, phosphoric acid; in the muscles,
on the other hand, only 0.48 per cent., in the blood 0.13 per cent.,
which is in thorough accord with the results of the different inves-
tigators mentioned above.
   We are not warranted, however, in  concluding that the  nerv-
ous system contains an absolutely larger quantity of phosphorus.
The quantity  of  phosphorus in the nervous  system  cannot be
gauged by the amount  of phosphorus in the excretions, for, as 
      Aqueous Extract—Lactic Acid- —Hypoxanthin.  235

Voit has determined, the entire nervous system of man contains
but 12 gr. of phosphoric  acid as compared  with 130 gr. in the
muscles, and 1,800 gr. in the bones; and, besides, we know, ever
since  Chossat's starvation experiments were published, that during
starvation  the nervous system  shows  no  appreciable  loss  of
weight.
   Petrowski has determined the percentage  of water  in  the
brain, and has found  it  to amount to 81.6 per  cent, of  the gray
substance, and 68.35  Per cent, of the  white substance.
   Quantitative  examination  alone  is  able to furnish  positive
evidence of the nature of cerebral  elements, for, as  Drechsel has
shown in Hermann's  " Handbook of Physiology," substances vary-
ing in quality  cannot be obtained in a pure state from one and
the same brain ;  and the terms  lecithin,  cholesterin,  and cerebrin
designate mixtures only:  of which  lecithin applies to the sub-
stance composed of phosphorus which has been dissolved by ether
and alcohol ; cholesterin is the term given to the ethereal extract
which remains after  removing the lecithin ; and cerebrin  desig-
nates the substances which  form crystals in hot alcohol, but are
insoluble in cold  alcohol.
   The aqueous  extract of the brain  was examined by W. Mtiller,
and  was found to yield large quantities of inosite,  8 per  mille ;
lactic acid, 5 per  mille ; kreatin, 4 per mille ; in  lesser quantities,
uric acid, xanthin, hypoxanthiu, urea, and leucin.
   It is worthy of notice that the  acid reaction of the  brain,
which becomes more acid as the brain dies away,  is attributed  by
Gscheidlein to a  fermenting  lactic  acid,  which can be obtained in
the form of a lactate of lime (Hoppe).   The reaction of the white
substance, however, is not acid, but neutral,  turning  alkaline with
the onset of death.   Consequently,  the brain does not,  as Funke
supposed, give a purely acid reaction.   Kossel  derives the hy-
poxanthin from nuclein, which is obtained by weak reagents from
the latter without setting up a general decomposition.   He con-
siders it a temporary product in the development of urea from
the  decomposition  of  more highly organized nitrogenous sub-
stances.  Hoppe-Seyler found  that  caustic potash  acting upon
nuclein at a temperature of 2000 Celsius, liberatedprussic acid and
ammonia ; and Kossel remarks that the conditions for the develop-
ment of the cyanides, which are intermediate products of the meta-
bolic processes, are to be found in substances obtained  from cell-
nuclei.  This chemical fact  is interesting enough physiologically 
236                      Psych iatry.
as proof of the  correctness of  Pfliiger's views, who held  that
certain phenomena due to irritation, such as epileptic convulsions,
which  are  believed by  Kussmaul and  others  to  be  caused by
the withdrawal of arterial blood, could be explained by the reten-
tion of metabolic products exerting an influence similar to that of
the cyanides.
   Cholesterin is one of the chief products to be extracted by ether
from the brain-substance.   Of this body Hoppe-Seyler says that
it is common to all living vegetable and animal  cells, but that it
plays no important part in the development of the cells;  that it is
in all probability  merely suspended, and not dissolved, in  proto-
plasm ;  that it is a product of decomposition resulting from  the
organic changes during cell-life.
   One of  the chief constituents of the  brain is protagon, which
was first obtained  by Liebreich.   It  contains  phosphorus, and
that too in  far greater quantities than nuclein, which was described
above.  Protagon and nuclein are the main depositories of brain-
phosphorus.   For  this reason,  if  for  no  other,   we  might
incline to  the view, that other chemical products of the brain-
substance,  such as lecithin, first  prepared from   the brain  by
Diakonow,  and Mtiller's cerebrin,  are  ingredients of  Liebreich's
protagon.   The  method of obtaining cerebrin  was refined upon
by Parcus, who divided cerebrin still further into  homocerebrin and
encephalin.   This view was  expounded first by Kuhne, and later
on  Blankenhorn  and Gamgee  investigated the  subject  again,
with the result of modifying  the  chemical formula of protagon.
Very  recently  Drechsel expressed  the conviction  that this view
was most probably  the correct one, but that the atomic weights
of lecithin  and cerebrin did not suffice  to  make  up  a  mixture
or union of the  nature  of  protagon, and that  still a third sub-
stance, containing more nitrogen and less carbon, would have to be
shown to exist, if Diakonow's and Hoppe-Seyler's views1 are to be
credited.
   It  has been urged  that the percentage of  phosphorus in pro-
tagon is exceedingly  variable in  quantity, and Diakonow  con-
tended  that  it  contained   no  phosphorus at  all, and  in  this
respect resembled cerebrin.   But Diakonow himself was unable
to prove this, and the former objection is answered  by the investi-
gations of  Blankendorf and  Gamgee, who found that  though
protagon had been re-crystallized four or five times, the percent-
1 That protagon is merely a mixture. 
Protagon.
237
age of phosphorus remained the same;  and this view is upheld by
Drechsel.  The formula of  protagon, as determined by Blanken-
horn and Gamgee isC160 H308 N5 P035.  That it is present in the
very earliest stages of brain development maybe inferred from its
importance as one of the main constituents of the brain, and from
the fact that it is easily precipitated by weak chemical  reagents
as a crystalline precipitate.   After extracting the cholesterin with
ether, it is separated out by alcohol (85 per cent.) at a tempera-
ture of 450 C, after the  dehydration of the residual  brain-sub-
stance, amounting to 31.65 per cent, of the entire brain-substance;
by gradual cooling it forms into needle-shaped or star-like groups.
To the arrangement of these crystals in nerve-marrow, in a direc-
tion radial to its axis, Kuhne attributed the double refraction  of
this substance.  Ebner, in his studies on the anisotropia of organic
substances, takes issue  with Kuhne, for he finds that treatment
with cold ether destroys the double refraction, whereas protagon
is entirely insoluble  in  ether.   Lecithin  and  cerebrin  are pre-
pared by much more complicated chemical methods.   To obtain
pure  crystals of  cerebrin some thirty odd re-crystallizations must
be performed, while lecithin (according to  Diakonow) does not
crystallize at all, or  is precipitated with great difficulty  only by
ether at a temperature  of O0 C.
    The presence of  a body like protagon in the brain is  rendered
plausible by  the physical  properties  of  the  latter,  which,  as
Kuhne puts it, do well in  participating in  the composition  of  so
peculiar a substance as the medullary sheath.  Among these peculiar
qualities is the power the medullary substance of the brain possesses,
of reducing osmic acid, and turning a black color ; but these pecu-
liar qualities are common also to the  myelin forms of protagon
resulting from  prolonged  contact of protagon with water.   Like
nerves themselves, protagon develops forms of myelin in the initial
stages  of  decomposition.   Before protagon is thoroughly  dehy-
drated by  drying over sulphuric acid, it gains  a  waxy appear-
ance ; it  swells in water,  changing  to a transparent, starch-like
mass ;  when dissolved it  invariably becomes opalescent.   Here-
after we shall see that pathological conditions of nerves give rise
to similar appearances.
    Though lecithin  and cerebrin (the latter a  substance without
phosphorus) exhibit the starch-like properties  of  solutions and
;nyelin-like forms, there is not  sufficient  ground  to  doubt  the
o;-i'/i:i of these substances from the protagon  of the brain,  but 
20u
Psychiatry.
their marked hygroscopical properties stand in broad contrast to
the lack of such qualities in protagon.  This was first mentioned
by Diakonow and Miiller, and has been insisted on since by Blank-
enhorn and Gamgee.  If protagon were a mere mixture of cerebrin
and lecithin, it would be difficult to conceive how a non-hygroscop-
ical body  could result  from  the union of  two hygroscopical
bodies.   It would be  more  natural to  suppose that the hygro-
scopical properties were the result of the  more elaborate methods
by which cerebrin and  lecithin are recognized as  secondary brain
constituents,  while protagon, a primary brain-substance, is obtained
in advance of these.
   The chemical composition of cerebrin is indicated by the for-
mula CG9.08 H11-47  N2.13 (Parcus), and of lecithin by the formula
C44 FI90 NP09 (Diakonow).  The formulae do not contradict the
premise of Liebreich and others, that  protagon divides  primarily
into cerebrin and lecithin.
   Hoppe-Seyler  holds  that lecithin, which  is  a phosphorous
body, can be found in  all cells capable of development, in rapidly
proliferating  pathological  tumors,  in  sperm, and in the yolk of
eggs, from which it has derived  its  name.   Both lecithin and pro-
tagon split up at a temperature  of less than ioo° C. into glycerin,
phosphoric acids, fatty acids, and the base,  neurin, which lacks
phosphorus, and is precipitated in the form of needle-shaped crys-
tals. Protagon yields stearic acid, while the various forms of leci-
thin divide up into palmitin and oleic acids. Considering the small
amount of nuclein,  the phosphoric acid  of the brain is certainly
not confined  solely to  the two  phosphorous  bodies, for Geoghe-
gan found, after removing the substances classed under lecithin,
that the brain-ash still contained 23 per cent, of phosphoric acid.
   Petrowski has made quantitative analyses of the gray and the
white substance.  Drechsel's critical observations, regarding the
inaccurate preparations of lecithin and cerebrin must be taken into
account.
                    PETROWSKl's  ANALYSIS :

    Water     ....
    Solid residue contained  therein
    Albumin  and  glutin  .
    Lecithin   ....
    Cholesterin and fats .
    Cerebrin   ....
    Substances insoluble in  dehydr;
    Salts.....
Gray.	White.
81.60	68-35
18.40	31-65
55-37	24-73
17.24	9.90
18.68	5I-91
°-53	9-55
tted ether, 6.71	3-34
1.45	°-57
 
Neurokeratin.
239
   According to Bernhardt, the percentage of water varies very
much in the different portions of the brain.  The cortex contains
86 per cent. ; the medullary substance of the hemispheres, 70 per
cent. ;  the oblongata, 74 per cent. ; while the cervical spinal cord
contains  73 per cent, of water, the lumbar cord y6 per cent., and
the sympathetic 64 per cent.
   Ktihne's and Ewald's neurokeratin is soluble only in  a hot •
concentrated solution of  caustic potash  and sulphuric acid, and
amounts to but  15 or 20 per cent, of the dried residue of the alco-
holic  or ethereal extract  of  the brain.  Petrowski insists that
lecithin and cholesterin  found  in  the  gray  substance do not
originate  from  the white  substance mixed  with  it,  but  from
the cells  of the  former.    That the  phosphorous  substance  in
the medullary  substance  of  the brain  is not  lecithin,  but  a
body  peculiar  to  the  brain  substance—say,  protagon,—would
seem  to  be proved  by  the  fact  that the  biological  impor-
tance which Hoppe-Seyler attributes  to lecithin would presup-
pose an increase  in  the  number of  tissue elements.  But for
some  time  previous to birth  there  is no  such  increase  of the
elements  of  the normal  brain-tissue.  There  is  one occurrence,
however,  which could be held  responsible for an increase of the
tissue-elements, and that is  the formation of fatty granular cells,
preceding the  development  of medullary sheaths, and  taking
place  about the time  in which the original gray cerebral substance
is transformed into white  substance, and before the  medullary
substance has been developed.  But the process is not  re-enacted
during normal  life;  whence  Hoppe-Seyler,   following  Kuhne,
infers that the white substance of the brain is intended for isolated
conduction, and on the other hand points to the fact  that rapid
perception and movement are effected by medullated fibres, while
the unstriated muscles (non-volitional) are supplied by non-medul-
lated  nerve-fibres.
    Nowhere in the system, though  widely scattered,  is lecithin
called upon to  effect such conduction as falls within  the province
of the cerebral medullary substance.   There is better reason, there-
fore, to presuppose the existence in the above tissue of a uniform
but more  complicated chemical substance.  Pathological increase
of nuclei, and  possibly also of nerve-cells, certainly does  occur;
and as it is always preceded by division of the nuclei, we may look
for a second phosphorous body well adapted to  effect such changes
of form, which  could be naturally associated in our minds with an
increase of such elements. 
240
Psychiatry.
   As regards the relation of protagon to the rapidity of conduc-
tion, we have two reasons for supposing the medullary substance
of the nerve-fibres  to  be  functionally  connected rather with
the nutrition  of  the fibres  than with conduction.  Rapidity  of
conduction might be held to depend upon favorable conditions of
nutrition,  furthered  by the composition of the medullary  sub-
stance.   Conduction is effected by non-medullated  fibres also.
It is initiated at the periphery, where the terminal branches of the
nerves, and probably of the axis-cylinders also, are non-medullated,
and at the other end conduction is originated in the gray  centres
in which the axis-cylinder passes into the  non-medullated  pro-
cesses of the ganglion-cell.
   From the laws of Ritter we know that motor nerves, after sec-
tion, begin to die at  their central end, whence they have received
their  stimuli, and that  cut  sensory nerves begin  to atrophy  at
their peripheral ends, for it is at the periphery that sensory stimu-
lation is started.   On the one hand, nutrition depends upon the
non-medullated tissue of the axis-cylinder, which receives central
and peripheral stimuli; and furthermore the stimulus itself supplies
the incentive for nutrition.  This would signify, according to Vir-
chow, that the axis-cylinder exercised a powerful attraction upon
the nutritive plasma, which is rendered most effective through the
mediation of stimulation.  We must look upon the medullated sub-
stance as a tissue favoring rapidity of conduction, and aiding the
nutrition  of the  axis-cylinder.   If  the venous  character  of the
blood which leaves the brain necessitates our considering a process
of oxydation in connection with nutrition, then we may assume this
medullated substance to be  concerned in this, for  this substance
is able to  reduce  osmic acid by  withdrawing oxygen,  a chemical
process in which  its large percentage of phosphorus plays  an im-
portant role.  Kuhne calls attention, from the chemical stand-
point, to  the  slowness of nerve-conduction,   first  proved   by
Helmholtz.  This slowness does not argue in favor of the  conduc-
tion of a  physical force such as electricity, but suggests rather
the progress of chemical changes  from section to section  of a
nerve, while it is  acting as a conductor.  The axis-cylinder alone,
because of its continuity, can  be engaged in nerve-conduction.
The medullary sheath is not continuous; it is interrupted (only) in
the region of Ranvier's constrictions; here the  medullary sub-
stance appears  interrupted, but  not so  the  primitive  sheath.
Rumpf has shown, that if the medullary substance is forced out 
Keratoid Sheaths Regulate  Nutrition.       241
by allowing the  axis-cylinder  to  swell  in  water, that the white
substance is checked momentarily in its course at the constriction-
rings, but the current pushes  on  within  the primitive  sheaths
through and beyond the constriction rings.   Secondly, the septa of
Lanterman divide the white substance into a number of segments,
which seem as though they had slipped into one another like  the
two divisions of a box.  The digestion  experiments of Kuhne and
Ewald,  and the  investigations of  Rumpf, have shown that  the
septa contain horny substance, which  intervenes between  the
sheath of  Schwann and  the keratoid sheath of the  axis-cylin-
der,  and furthermore  that  a  framework  of  horny  substance
traverses  the white  substance between  the segments.  Those
complicated structures, which Stilling was the first to describe as a
system  of tubes and trabeculae are probably synonymous with
this keratoid network.
   If the expression keratoid substance could be applied properly
to the sheaths of the white substance and of the axis-cylinder, then
the axis-cylinder could be considered isolated from the white sub-
stance by a body far less permeable than either the white substance
or the axis-cylinder.  The correct expression, horn-bearing sheaths,
points to the fact that the keratoid substance  is interrupted by
substances favorable to a nutritive endosmosis.   Since the axis-
cylinder  is better adapted  during stimulation to attract chemical
substances  from the white substance, and  in keeping  with  the
greater rapidity of conduction in medullated fibres to increase the
chemical processes involved in conduction, its  sheath, consisting
of horny and glutinous substances, may be held to represent a
sieve which allows the nutritive  plasma,  as much at least as is
attracted from the white substance, to fall upon the axis-cylinder,
not with the intensity of a full current, but with the more delicate
force of a rain ;  and we must regard the partial endosmotic per-
meability of the neurokeratin sheath as an  apparatus  regulating
the physiological needs of the axis-cylinder.   But the white sub-
stance of peripheral nerves also is surrounded by a similar horny
sheath, and interrupted in its interior.   The  aforesaid  regulation
of the nutritive plasma applies to the sheath of Schwann as well.
In this way the  nutrition of the white  substance is made indepen-
dent of the plasma exuded by the blood-vessels, and a uniformity
in regard to  its chemical changes is  established.  This is sug-
gested also by the peculiar conditions of nutrition,  since  the
broad  meshes of  the  vascular network  of this  comparatively 
242                      Psychiatry.
anaemic white  substance are to be  found only on the surface of
complicated bundles, whereas the single nerve-fibres have no sort
of contact with the blood-vessels from which the plasma that is
exuded permeates the sheath of Schwann, and  mingles  with the
white substance drop by drop, instead of pouring in upon the latter
with its entire mass at once.   The numerous interruptions through
horny substance in the white substance would impede any simple
mode of nerve-conduction, but would favor an endosmotic pro-
cess, advancing slowly from segment to segment.
   The electrical nerve-current is probably to be regarded merely
as a secondary phenomenon accompanying chemical  changes.
This  secondary phenomenon has been specially  studied, how-
ever,  by nerve-physicists.  Dubois'  (Reymond) nerve-current of
rest, as  is well known, is not connected with any process of stimu-
lation.  It suffers disturbance  through negative variation.  The
chemical nature of nutritive processes could be studied by  careful
examinations  of  daily secretions;  and many chemists  have
sought to determine the quantity of  phosphorus contained in the
excretions  of the  body, starting out on the supposition  that  the
nutrition of the nervous system is to be held to account for a consid-
erable portion of the phosphorus in the urine and faeces.  On this
head, Mendel's observations on the percentage of phosphorus in
urine are  specially worthy  of notice, as well as some other obser-
vations  to  which  Mendel  refers in  this same treatise.  Mendel
inquired into the variations in the quantity of phosphorus present
in the urine during waking and sleeping.  He found the nocturnal
urine richer in phosphoric acid than the urine passed during  the
day; whence we infer that the waste products of the brain are
increased  during  sleep.   This  fact  is  in  perfect  accord with
Burckhardt's observations regarding the movements of the brain.
Burckhardt established a direct mechanical relation between  the
vascular wave and the removal  of the  lymph-current; and main-
tained, moreover, that while  the  brain was awake and  active—
e. g., while the  brain was  in a state  of excitation—the  effects
of the vascular  wave were interrupted  and irregular ; but  that
regular  peristaltic vascular movements were peculiar to sleep, and
that  the complete chemical restitution of the brain during sleep
must be ascribed to  the increased deportation  of its  waste pro-
ducts.   Mendel  refers in his article  to the observation of Wood,
that mental activity slightly increased the alkaline phosphates of
the urine,  but  that it caused a greater  and  decided diminution 
          Nerve-Current  and Negative Variation.     243

of the earthy phosphates.   He  concludes, therefore, that nerve-
tissue  increases,   like  muscular  tissues,  during  mental  work,
thereby  entailing a diminution in quantity of the phosphates
excreted.  The  chemical phase of excitation  seems  to him to
involve a synthetical chemical  process and a decrease of  waste
products.  This  view becomes attractive, if we remember that
the phenomenon of memory is a positive action which has out-
lived  the process of excitation, and it is much more conceivable
that a synthetical chemical  process should leave lasting functional
consequences, than  that functional acts  should arise  from the
decomposition of waste products  soon to be  discharged.   The
nerve-current of  rest, together  with  the increased products of
chemical decomposition and the mechanical  methods for the
removal of waste products,  exists also during sleep.  If the func-
tional excitation of  the axis-cylinder, whether central  or periph-
eral, results in the withdrawal of a phosphorous substance from the
white substance  through the horny sheath, and in utilizing this
phosphorous substance in a synthetical chemical process, then the
chemical process going on  in the white substance and connected
with  the nerve-current  of  rest  will be disturbed ; and, further-
more, the electro-negative variation would correspond to a synthet-
ical chemical process in the axis-cylinder and the nerve-cells as
the very opposite of a metabolic process of division (Spaltungsvor-
gang).
    Rumpf's  investigations  have shown that the nutrition  of the
axis-cylinder depends, apart from  the  possibility of isolated and
rapid conduction through the medullary substance, upon stimuli,
and consequently upon its connections with a sensory apparatus at
the periphery, and  with a  central organ.  Rumpf's observations
were made on nerves which remained within  the living  body, but
which  were  severed both  at their peripheral and central  ends.
 Under these circumstances the  axial band  disappeared and was
dissolved, within twenty-four to seventy-five hours, even  if the
 nerve had been  kept  in a  proper menstruum.  The influence
 of the medullated substance and the blood-vessels does not suffice
 for the nutrition of the  axial fibre.
    This experiment proved at  the same  time  that the fibrillary
structure of  the axis-cylinder, which Max Schultze inferred from
 the striated  appearance of the axis-cylinder and  of the cell-pro-
cesses, after treatment with silver, did not  in reality exist, but that
 this  striation was due  simply  to a precipitate of silver in the 
244
Psychiatry.
folds of the keratoid  sheath.   Rumpf was  able to demonstrate
this same silver-striation in sheaths which we but just learned did
not enclose axis-cylinders.
    The keratoid sheath of the axis-cylinder  and white substance
might possibly, by reason of the pressure it exerts, be of some mo-
ment as regards the more delicate conditions of normal nutrition.
This applies to the horny sheath of the axis-cylinders of the brain,
but all brain fibres as well as all fibres of the optic nerve and of the
spinal cord lack the sheath of Schwann.  But in lieu of the pressure
which the sheath of Schwann presumably exerts on the white sub-
stance, another  force comes  into play in the  cranial  and spinal
cavities, which, as far as the medulla is concerned, is indicated by
the tension  of the membr. atlantis.  From the  chemical standpoint,
the greater wealth of water of  the brain and spinal cord must be
borne in mind ;  this might be thought  to correspond  to  the
greater  quantities of plasma exuded  in consequence of  the  ab-
sence of the sheath of Schwann.
   This indirectness and independence  in the matter of the nutri-
tion of the axis-cylinder would seem to  be a safeguard  to prevent
the disturbance of its  function by cerebral hyperaemias.  Under
normal  conditions of  stimulation  and  attraction of  the  axis-
cylinder, as  well as of  the  ganglion-cells,  and with an  abundant
ramification of  wide arteries, the  brain  appears by its  normal
structure to be protected against the possibilities of anaemia ; for in
a body wasting from starvation  the central nervous system, it is
claimed, suffers less in weight than  other organs of the body, and
it is well known, furthermore, that cerebral activity is possible in
spite of general anaemia of the body.
   In consequence of  its larger percentage  of water, the gray
substance would influence nutrition in a very different  way from
the axis-cylinder,  which, throughout its  course in the  central
white substance, and in the peripheral nerves, has the function of
a conducting organ.  The variable nutritive conditions are depen-
dent upon the gray substance to the extent  that  they are in-
fluenced by the  blood-supply.    Since  albuminoid substances
aggregate to more than one half of the chemical constituents of
the gray substance, we may  infer a  direct relation  to exist  be-
tween the albuminoid bodies and the percentage of phosphorus,
and the latter would be greater than in  the case of other  cellular
tissues,  for  even  the  connective tissue  of the  gray   substance
contains more albumin than the connective tissue elsewhere does. 
Nutrition  of Axis-Cylinder.           245
This  then, is another factor accounting for the greater accumula-
tion of brain-phosphorus.
    Because of its greater wealth of  cells, the gray substance  con-
tains  a larger quantity of  nuclein ; but  nuclein stands next to
protagon in the series of  cerebral bodies containing phosphorus.
LTnder normal conditions, and  in the  fully developed brain, nu-
clein  does not seem to play an important role, as regards the
increase of tissue, as  it does in pus, in yeast, and wherever else it
is found.  After excluding this particular function, and in addi-
tion to its adding merely to the  percentage of brain-phosphorus,
we  may insist on the fact that the nucleus exercises a nutritive in-
fluence over the albuminoid protoplasm.   This nutritive function
for  the maintenance of the protoplasm is annulled in  pathologi-
cal  processes of the brain as soon as the division  of the  ganglionic
nuclei enables the nuclein to develop its faculties for regenerating
tissue, while the protoplasm  of the cell-body is diminished  and
finally destroyed.
    The nutrition of the axis-cylinder,  which is  a part  of  nerve-
cells and  of  their  prolongations, some  of  which become axis-
cylinders, is effected  in a similar manner.   Jastrowitz  considers
the  gray substance  (pp. 58, 59) the medium of  isolated conduc-
tion, to the extent that such conduction is imposed upon the gray
substance.   If the striation of the axis-cylinder,  and the striation
which Remak observed on the ganglionic processes, and Schultze
(p. 62) within the  cell-protoplasm,  indicate  an identical process,
(while, according to Rumpf, it is simply an expression of the folds
in the keratoid  sheaths,) then we should have  to suppose such
striation  to  exist also in  the  case of the  nerve-cells and their
protoplasm.  It is quite conceivable also that a sheath surrounding
ramified nerve-cells, which has as many points of attachment in the
connective tissue as it has branches, should, if isolated and separated
from these points of attachment, lose  its normal tension, and be
thrown into folds occupying all possible directions.  The lines of
Schultze, which Boll demonstrated,  with  the aid  of osmic acid, in
cortical cells also, both in  those forms which extend  from  one
process to the other and in  the dark lines running concentrically
around the nucleus, might be ascribed  to simple folds without a
minute fibrillary structure.
    The larger quantity of plasma in the cortex depends  upon its
denser network of blood-vessels.  The nutrition of the nerve-cells is
regulated  specially by the sieve-like perforations of the  keratoid 
246                      Psychiatry.
sheaths, while the short distance which the naked nerve-fibre
has to travel from its origin in the gray substance before it is sur-
rounded by a medullary sheath, does not  influence the rapidity of
conduction.   And on the  other hand, the network of  gray
fibres does not become medullated either.  But the very obstacles
to irradiation, causing slowness of conduction in the gray sub-
stance (p. 185), might be explained  by the  dropping off  of the
medullated  substance from the  anastomosing processes  of nerve-
cells, since the medullated substance  is justly considered to favor
rapidity of conduction.
   In order to comprehend the mode of nutrition during cerebral
activity, we must, if we wish  to avoid confusion, omit the  consid-
eration  of irradiation in the gray substance, although there is no
reason to suppose that any active cerebral process excites but  a
few  nerve-cells only.   For this reason we must  presuppose an
irradiation of moderate extent to  take place whenever a number
of cells  unite for common action.  The development of a single
thought is  effected by the   functional  activity  of association-
bundles, which  unite in a   very complicated  way  the com-
ponent   elements  of  a  so-called   residual  image  of   the
cortex.    These   groups  of   associated cells   which   harbor
residual  images,  are  the starting-point  for the  excitation  of
more comprehensive  associations, constituting simple processes
of induction (Schlussprocesse) (p.  153).   It  has  been  explained
above that the entrance of numerous and  comparatively indepen-
dent arteries of the pia into the broad expanse of  cortical  surface
favors  the  excitation of separate and  well-defined groups  of
ganglion cells, and we must remember that  every cortical image
and every inference depend upon  the union  of special groups of
cells.  The  projection-system  alone  stands  under the  influence
of centres pf excitation, for as soon  as the fore-brain comes into
play the activity of the association-fibres precludes the possibility
of localizing the cerebral excitation.    We must admit, therefore,
that  the localization  is but  an aid  to the  grouping of  stimuli
differing from one  another  in  their relations  to  time  and
space ; they are united for a common action by the process of
association—a process  which  cannot  be confined to  any one
portion of the cortex, as  is amply demonstrated  by the varying
lengths of the association-bundles which unite the remotest parts
of the cerebral lobes.
   It is worthy of remark, that every process of thought ema- 
Nutritive Attraction.
247
nates from  a residual image of the cortex, and that this image
is connected with a  large number  of  distinct cerebral foci.   The
individual  mental  act  is   so  constituted,  however,  that  the
initiatory residual image enters into a lesser number of  connec-
tions than the actual anatomical connections would warrant.  In
every mental act but a portion of the possible available  associa-
tion-tracts are employed.   If the functional activity of the cortex
implies a synthetical chemical process, then  the active brain-
cells and brain-tracts will require an increased quantity of  plasma.
We  can understand  the  possibility  of  isolated  conduction by
attributing to the nerve elements a nutritive attraction along the
course of the arciform bundles.  If we accept Fechner's theory,
that the cortical images and their connections may be stimulated
to one of  two variable  degrees of  intensity, and  that  in  any
particular mental act those images which are actively  utilized
stand above  the  threshold of consciousness while others remain
below the level of consciousness, then accepting this theory, we may
interpret it to mean that elements  bearing processes standing
above  this level exhibit a greater  nutritive attraction than those
elements which are  not then called into play.   This is a distinc-
tion of degree, not  of kind, for certain stimuli can  be  perceived
without being clearly recognized by  consciousness,  and,  further-
more, synchronous or successive stimuli can become associated.
These associations may be formed unconsciously, i.  c., below the
threshold of  consciousness, and  yet they may  rise above  this
level, and into consciousness as complete inductions (inferences),
if any groups of elements  in these regions will by association stim-
ulate nutritive attraction to such a degree of intensity, that these
groups can pass from the  condition  of  partial sleep to  that of
partial wakefulness.
   From a consideration of the cerebral mechanism we learn  that
in addition to the influence of attraction, there exists a nutritive
process which, apart from  the  influence of the heart, relies upon
the effectiveness of the vaso-motor centre; whence it follows that
functional hyperaemia cannot be put solely to the account of attrac-
tion.   Analyzing the independent manner in which the vaso-motor
centre influences the brain, as is exhibited by the vascular wave,
we find that we get  the vaso-constrictor influence with the arterial
systole, and  the vaso-dilator influence with the arterial diastole.
But  the mental processes are not interrupted by each  arterial
systole, for which reason they must, to a certain degree, be  inde- 
248
Psychiatry.
pendent of functional hyperaemia.  This independence of mental
acts may possibly be due to the fact that the cortex itself acts as a
vaso-motor centre  in its  relations  to  subcortical centres.  This
cortical function  is the very  opposite of functional hyperaemia.
If functional hyperaemia  is caused by stimulation of the cortex,
starting the mechanism of association, then  the constriction of
the blood-vessels is the result of cortical stimulation, and this dila-
tion (p. 189) must be considered the result of inhibition of cortical
function.  We must look to another fact if we wish to understand
the nature of the functional  hyperaemia which helps and, for a
certain length of  time, enables the  plasma to exhibit its phenom-
ena of attraction.
   Fechner denies the  spontaneity of motor  acts, which, if they
were spontaneous, would not obey the universal law of the conser-
vation of  energy.  According  to  this  law,  energy cannot  be
generated,  except  at a loss  of  other energy.   He  proves  the
applicability  of this law to cerebral activity by  referring  to  the
common experience of  all that muscular and mental energy can-
not be generated simultaneously by the brain.   A person who is
engaged in physical labor will, as soon as a mental process is set
up, allow an  arm that was raised to fall; and, conversely, severe
physical exercise  disturbs any process of thought.  The inference
is, that functions  of the fore-brain  inhibit one another, according
as one  or  the other  happens to predominate in the fore-brain.
Goltz demonstrated the inhibition  of the croak-reflex in the frog
through  other stimuli   acting  simultaneously  upon  the gray
substance.
   But from  the investigations of Burkhardt we  learned that the
influence of the vaso-motor centre upon the peristaltic vascular
movements is modified by the activity  of the hemispheres, and
that when this activity is lowest, as it  is in sleep, arterial systole
and diastole succeed one another with the utmost regularity.   It
is evident from the influence of cerebral activity over the vaso-
motor centre, that  the  vaso-motor nerves of the cortex do  not
reach the blood-vessels at  once, but  that  they are interrupted
in the subcortical vaso-motor centre ; and that  for the vascular
innervation of the cortex, the  subcortical centres  must constantly
be called into requisition.
   I  remarked   above   (p. 207) that  the  vaso-motor  centres
governing  cortical  influence must  be referred to the oray sub_
stance of  the anterior  division of the brain-trunk, in which  are 
       Influence of Cortex upon  Vaso-Motor Centre.    249

situated also the  other motor tracts subject to centrifugally trans-
mitted  cortical innervation.   If  the  cortex be  excited  in its
capacity as  a  vaso-motor  centre,  the  influence  of  the arterial
systole  upon the  vaso-motor  centre  will be augmented,  thus
causing active anaemia of the brain, which, as a rule, remains
entirely  independent of  the anaemia of  the rest of  the body.
But since a functionally active cortex cannot impede the devel-
opment  of  functional hyperaemia, we  must assume that the
physiological excitation of the cortex increases in a  centrifugal
direction the arterial diastole which forms part of a peristaltic move-
ment.   This would be quite comprehensible,  not only if an active
cortical process,  such as  a thought, would, as Fechner contends,
interfere with the evolution of intense conscious movements, or
vice versa, but also  if  the process of association would inhibit
the second motor function of the cortex—viz., the constriction of
the arteries.
    I made mention of  this division of cortical energy in favor of
functional hyperaemia, in speaking of the relation of this hyperaemia
to  an  aggressive emotion  (p. 195).  On  the other  hand, again,
deficient or diminished cortical activity, as expressed in conscious
movements, or in thinking, would be attended by an  augmented
excitation of  the  vaso-motor  nerves  connected  with this  very
portion of the cortex, and would  deprive the attraction of the
nervous elements through exosmosis of adequate material, just as
reflex  impulses  from the  periphery  cause a constriction of tne
cerebral arteries through the mediation of  a subcortical vaso-motor
centre, and thus  influence the blood-supply as well as the chemical
changes in the brain.
    Figures 64 and 65 are intended  to illustrate in a diagrammatic
way the manner in which excitation of the cortex and excitation
of  the  vaso-motor centre inhibit one another.  Each one of the
three  different  cortical  regions performs two different kinds of
work :  Through  the  U-shaped bundles JA., JA., processes of asso-
ciation receive their innervation,—thought  is rendered  possible;
while the projection bundles JV. and JN.  transmit cortical stimuli
to  the vaso-motor centre CMU.  and CVM.1
    Figure  65 exhibits the  association-bundles with the  arith-
 metical sign >  (larger) appended, and the  vaso-motor bundles
 with the arithmetical  sign < (smaller) ;  in  addition  to this  we

    1 The wood-engraver  is  responsible for this difference on the two diagrams in
 the lettering of parts  that are identical. 
250                         Psychiatry.

note that the  blood-vessels  of the brain-substance are indicated,
and are larger on Fig. 65 than on  Fig. 64.  This difference of in-
nervation exists at all times, and the diagram is intended  to show
that  increased functional  activity of  the cortex is followed by a
diminution in cortical  vaso-motor influences ; whence it  follows
                                 Fig. 64.
       Diagram of Vascular Innervation during Increased Vascular Pressure.
    C,  C, C. Three regions of the cerebral cortex, connected with association-bundles
A, and  with vascular nerves V.  A. Association bundles.  > J A. Inhibited associa-
tion.   < JV. and  < JN.  Increased vascular innervation, consequently the blood-
vessels  are drawn narrow,  nucl. lent.  Lenticular nucleus.   Th. Thalamus.  CMU.
Vaso-motor centre.
Diagram of Vascular Innervation during Functional Hyperaemia.
    C, C, C. Three regions of the brain which are cpnnected with association-tracts
A, and vaso-motor nerves.    < JA. Increased associations.  JV. < Vascular inner-
vation checked, consequently diagrammatic blood-vessels are dilated.  Lent. N.   Nu-
cleus lenticularis.   Th. Thalamus.  CVM. Vaso-motor centre. 
             Functional Hyperemia—Blushing.         251

that a cortical process of association by inhibiting vascular inner-
vation will  result in immediate functional  hyperaemia.  In the
diagram, Fig. 64, the association bundles have received the mi-
nority sign <, and the tracts for vascular innervation the plurality
sign >.  The three diagrammatic arteries are here represented
narrower than in Fig. 65.  The diagram signifies, furthermore, that
if a slight functional activity of the association-tracts does not
produce  functional hyperaemia,  the  influence of the vaso-motor
centre will not be checked.   At the same time it is shown in both
diagrams by means of arrows that the cortex imparts a centrifugal
impulse to  the vaso-motor  centre, and that in some way or other
this impulse is transmitted in a centripetal direction from the sub-
cortical centre reacting upon the vascular system.  A graphical
statement of these facts would read thus :
       Process of association > = vascular innervation  <
                              and
      Process of association < = vascular innervation > || }
    Innervation  of  the  arteries  is invariably the result  of the
functional  activity of a subcortical centre ; from  which we  infer
that the whole condition of functional  hyperaemia is based  upon
the  cortical  inhibition  (p.  197) of  a  subcortical  centre.   The
existence of  general cerebral fluxion  during and after mental
work forbids  the inference  that functional  hyperaemia depends
altogether  upon the attraction of  stimulated  nerve-elements.
That this  fluxion extends  beyond the  brain would seem  to be
proved by  the physiognomical phenomenon of blushing.
    Blushing is often the concomitant condition of a multitude of
associations.  The wealth  of simultaneously excited  nerve-ele-
ments interferes  with the  orderly development of thought; for
in this instance, too, the simpler the character of mental work the
more unrestrained will be the flow of association.
    A girl who recites a poem  from memory  will, by dint of cere-
bral association, be able to  repeat words and  verses in the proper
order of succession.  The  child will not blush if she happen
to recite the poem before children only ;  but the presence of the
kin^  would make it blush  and  stammer forth its  lines in  mere
confusion.    The sight of the monarch is connected with a larger
number  of  associations which  have reference  to his unusual
personality;  his presence will start a number of indistinct associa-

    1 The author uses these signs  rather  oddly. The signs > and < denote "in-
creasing " and " decreasing."—S. 
252                      Psych iatry.
tions.   The sum  of  the  cortical  elements thus excited will be
followed by paralysis of the vaso-motor  centre, and  will cause
much more widespread functional hyperaemia of the brain than
the task of reciting the poem did.  This degree of general hyper-
aemia will, in consequence of the numerous  and  simultaneous
inhibitory influences acting upon the vaso-motor centre from all
sides, cause a paralysis extending beyond the domain of  cerebral
vessels, and will thus produce blushing ; secondly, we may argue
that the many different  ideas  started in the child's  brain  will
inhibit one another and confuse the acts of the child.
    Every one  experiences a sensation of confusion at the be-
ginning of a difficult  mental task, for from  the  residual cortical
images  which  are  at  the bottom of any special  train of ideas,
more association-tracts will be  excited into action than  can be
utilized in  the orderly  evolution of  these  ideas.   Excessive
functional hyperaemia will be engendered, upon which will follow
a state of  mental confusion.   Walking  up  and  down, bodily
exercise of any sort, the sight of green fields,  will suffice to dis-
tribute  a  general  hyperaemia to  other parts  of  the cortex,  by
means of which the initiatory conception, with all the associations
connected  therewith, will be more sharply defined, and simplicity
as well  as precision of thought will be secured.   It  is only when
the disturbing influence  of superfluous hyperaemia has been re-
moved, that the process of attraction will insure the development
of thought to a purpose.
    By injecting the vessels of the brain it can readily be demon-
strated that  the blood-vessels run a radial course parallel to the
projection-systems, and an arch-shaped course along the associa-
tion-bundles.   The  course  the various  systems  of  fibres take
could be inferred from the distribution of the arteries as seen on
corrosion-preparations.   We can thus understand why functional
hyperaemia should favor well-ordered attraction along the lines of
association-tracts ;  but we perceive, too, that  a  large  number of
associations connected with the image just then above the threshold
of  consciousness will be equally favored ;  in which case many re-
sidual  images  will be called into  activity—i. c, will  pass into  a
state of superior  nutrition,  but to no purpose  whatever.  Such
secondary images  can, however, be  consciously utilized.  There
are easily aroused, though  generally neglected,  associations ex-
isting between  each word and its  assonances.  If thoughts are to
be expressed in rhymes, these assonances  rise into consciousness 
Assonances—Evolution of Thoughts.        253
and are interwoven with the ordinary train of ideas to the extent
that other associations  will  allow.   Every  oratorical  effort  is
likely to be marked  by secondary associations which were sug-
gested by the thought in words alone.   If we speak of certain
ideas as bright, we are easily led to think of things that are bright,
and we may compare such ideas to the light of the sun, and so on.
   The physiological isolation of certain association-tracts, to the
exclusion of the functional activity of secondary associations, may
be  explained  somewhat as follows :  A train of  thought starts
from a  residual image in the cortex.  All the associations con-
nected with this image are, as it were, ready for action.    But no
sooner has the cortical image been revived than a second  image
is  presented  before  our consciousness, which also exercises a
definite attraction.  The result is that the associations connecting
these two images are under double  attraction, and will  conse-
quently be more intensely excited than  any others.  The orderly
evolution of any one thought implies a starting-point and a goal
between which it  runs its course.   The  two images are at either
end of this course; and through a strict observance of this  course
a firm  union is established between them.   Just as a marksman,
in spite of numberless objects around him, establishes a direct re-
lation between his finger on the trigger  and the  bull's-eye  which
he is to hit, so a similar relation is established between  the two
terminal  images,  which  controls the  direction of  the  play  of
association.  And at the same time other images  from a parallel
direction are perceived in the horopter, which, after the shot has
been fired, may alter the circle of vision.
   The  so-called  unity of consciousness may be  likened to the
activity of the macula lutea, and the secondary association to that
of the horopter.  Below  the threshold  of  consciousness parallel
presentations  may arise, due to  attraction exercised along associa-
tion-tracts not connecting the starting-point with the goal  of the
thought then  before the mind.  Such parallel presentations may,
but  do  not  necessarily,  arise  from  previously well-established
associations.  They may have terminal images of their own  before
risinc  to the  level of consciousness.  The forces of  attraction
which  push them  above  this level  find  these images and associa-
tions well organized and ready for use.
    I shall have more to say of these parallel  images and associa-
tions in a later chapter of this book in  which I propose  to treat
of the mechanism of Expression. 
254                      Psych ia try.
   Both diagrams representing the inhibition of  the vaso-motcr
centre through  cortical  function, and the  inhibition of cortical.
function through the vaso-motor centre,  apply, as was stated
above (p. 195), to different stages of  emotion.  Burckhardt tells
us, moreover,  that the influence of emotion upon the vascular
wave is far more intense  than the influence  of thought.
   This greater  intensity is easily explained if we remember that
an emotion involves  our whole  individuality, and the functional
excitation of the widest  possible range of associations.   Whether
the arterial systole will be checked or increased will depend in the
one case upon the proportionate number of functionally liberated
nerve-elements,  and in the other upon  the number of nerve-ele-
ments already functionally engaged.  This is true, above all things,
of bodily pain.  A finger dipped in water  having a temperature
of 500 Celsius will give rise to a sensation of warmth ; if the arm
or the  entire body  be  immersed into water of  the same  tem-
perature, the sensation  of pain will be  engendered, for in the
latter instance a larger  number of  nerve-tracts  will have been
excited. So,  too, moderate illumination of the retina  effects
simple vision ; but the disc of the sun striking the eye  produces
actual pain, through  the larger  number of elements excited by
irradiation  from every optic-nerve fibre.  The retinal images of  a
stranger, and of a person whom we love or fear, are  entirely the
same, yet the sight of the latter two may produce an emotion in us.
For, in  this  instance, innumerable associations will  be  aroused
which are  connected with the images of these persons.  These
are  associations  of time and place when and where we met them ;
there will be a play of vascular innervation dependent upon the
excitation  of  fettered or unfettered moods;  many association-
fibres above  and below  the  level of consciousness will be called
into activity,— all of  which, and a complicated  process  it is, will
be due to the sight of these two persons.   The  sight of the one
beloved will  excite an unfettered mood  which is based upon  a
functional  hyperaemia, and  which will inhibit  the vaso-motor
centre at the beginning of the systole of its vascular wave.  The
sight of one we fear  will excite a  fettered mood, giving  rise to
associations, with  sensations of  vascular innervation, which in-
crease the arterial systole of the vascular wave. ■
   The nutrition of the  brain will be impaired by rapulsive emo-
tions, for it is undoubtedly the  arterial diastole  which removes
waste-products from  the brain.  We have  learned to  recognize 
Weight of Brain.
255
that the brain, by dint of the variable volume of the cranial cavity,
with the aid of the muscular  apparatus of  its blood-vessels, con-
tains within itself its metabolic mechanism ;  it is a pressure- and
suction-pump, forcing out  ventricular fluid, absorbing lymphatic
fluid from the various tissues into the perivascular spaces, and
pumping it from  these into subarachnoidal spaces.
   The state  of  the nutrition  of the  brain has an important
bearing upon  its weight  which we must now consider without
regard to its  specific  weight.  Neglecting, for the  present, the
statements of  older German authors, such  as Huschke  and
Rudolf Wagner,  we find, according to the valuable  statistics  of
Bischoff, that  the weight  of  the brain varies  in man between
1,018 and 1,925  grammes; in woman, between  820 and  1,565
grammes.  The  average  would be: For  the male  brain,  1,362
grammes ; and for the female, 1,219.   Pfleger's investigations have
shown that this statement  must be modified if the calculation is
based  upon adult brains alone, between the  ages of 19 and 58,
by  which means we get rid  of  a possible error due to senile
atrophy.   Weichselbaum  calculated the  average  brain-weight
of 390 Austrian soldiers, between the  ages of 20 and 48 years,
to be  1,373  grammes;  while Pfleger,  who  took the  brain  of
men up to  the  59th year, proved this weight to be  but  1,321
grammes.  This  discrepancy  I would not ascribe altogether  to
the ten  years  of more advanced age,  but rather to  the  more
powerful organization of  soldiers, whose exalted nutrition would
tell in the case of the brain also.
    As regards sex, there  is an undoubted difference of ten per
cent, (according to Pfleger of  thirteen per cent.), in  favor of the
male.   Nor is this difference proportionate to the difference  of
stature.  The average  statures of man and woman  are to  each
other as 100 :  93.2, while the male and female brain hold the rela-
tion of 100 : 90.93.
    Furthermore, various  authors, and among them  Le  Bon and
Bischoff, are agreed  to this, that there is a certain proportionate
difference between the length of the body and the weight of the
brain, but that the difference between the brain-weights of various
individuals is far greater than could be accounted for by the rela-
tive lengths of the body alone ; and  that this difference must
undoubtedly depend upon other conditions.   It is worthy of note
that short persons have a relatively larger brain than large persons.
The largest  brain  relatively speaking, is that of the new-born 
256
Psychiatry.
infant.  Its increase is so marked during the first period of extra-
uterine life, that Tuczek, basing his statements upon the investi-
gations  of  Huschke and Bischoff, contends that during the first
year of extra-uterine life the daily increase in the size of the brain
amounts to more than one  cubic centimetre,—i. c., about the size
of a bean.  There  is a direct connection between  the growth of
the brain,  the size, and the  quantity of blood  of the new-born
infant.   According to Hermann,  the  blood of  the new-born
amounts to -^, of the adult to T\ only, of the entire weight of the
body.  There is a direct connection also with the greater width of
the arterial system  in the  child, as was  shown by  Benecke ; and
there is no  doubt that the greater number of pulse contractions has
an  important influence upon  metabolic changes  in the body.
Benecke attributes  these to the smallness of  the infantile heart,
for the cardiac  contractions are  effected by shorter muscular
fibres in a shorter space of  time.  In the female, the lesser size of
the heart and the narrowness  of the vascular system are important
factors in determining the  growth of  her brain, and to these fac-
tors must be  added the higher percentage of water in her blood.
Briicke quoting Valentin's  tables on the sexual difference in  the
composition of blood, states  that the percentages of water in  the
blood of man and woman  are as 77.19: 79.11 ; of  the solid resi-
due as  22.1 : 20.89;  ^he number of blood  corpuscles  as  14.1 :
12.79.
    No positive conclusions can be drawn from the  weight of  the
brain ; the statistical average might be utilized, but the individual
case certainly not.   To take  a single  instance : The large size of
the skull in taller persons depends more especially  upon  the gen-
eral osseous system and the length of body (Pfleger).  The brain
filling this  cavity need not  necessarily contain a larger number of
nerve-elements, but it is more likely that it will contain  fibres of
greater  length,  for their  development will  be hampered  less,
the greater the width of the skull.   But that the  greater length
of nerve-fibres implies greater functional activity, as a larger num-
ber of elements would do,  has not been proven.
    I have  given preference  to  the  statistical results of Weich-
selbaum and  Pfleger over those of other authors, simply because
the former have enabled us to draw some  conclusions as to  the
proportionate weight of   the  different divisions  of  the brain.
They have made use of my method of dividing the brain :  Follow-
ing my  example, they do not join the cerebellum to the pons and 
Method  of  Weighiiig Brain—Statistics.       25
other parts of the brain ;  and, furthermore, they regard the brain-
trunk, including the  prosencephalic ganglion, as  the third impor-
tant  factor in calculating the  weight  of the brain.  This method
of separating the brain-trunk from its mantle, by cutting through
the  corona  radiata, is  illustrated in Figs. 16 and  17.   The brain,
together with its membranes, is weighed first, and its total weight
is calculated from the  sum of  the weights of each division of the
brain.   The  brain-trunk also  is divided up in the  manner I have
indicated, into  the lobus  candicis, including the fore-brain  gan-
glion and the island of  Reil;  into the  optic thalamus, the region
of the  corp. quadrig. and crura cerebri;  and  into the pons and
oblongata.

    In the following table I propose to give (for the sake of comparison, and to bring
out prominent and instructive differences in weight between the various divisions of
the brain in man and animals) some statistics regarding the proportional weight of the
different parts of the brain in various animals and  in man.  The animal brains here
referred to were  selected by chance rather than by intent, from a far larger (compara-
tive) anatomical collection :
Ba
O C O 1-.	0	si 'o 0	'5-■5 3 u 3 O	Cfl 3 m-E 3	c _o ■3 J3 a u a V	c 0 Ph
420	230	350	58	19	6-5	12
394	256	349				
350	180	470	40	30	10	IO
			40	16.9	15.3 IO.7	
300	255	444				
328	379	290	34-5	20.4	16.9	10.7
			25	12.5	19	15
Man (adult)
  ''  (new-born)
Monkey
Elephant *
Horse a
  "  b .   .  .
.Seal
Bear  ....
Dog   ...
Pig   .  .   .  .
Roe   ...
Cat   ....
New-born rabbit
780
830
708
630
604
698
^73
644
728
615
622
614
611
105
057
085
239
190
105
148
146
090
120
122
105
112
20S
125
204
196
177
209
1S1
265
255
140, 245
063 324
 4-5

  10

16.9



17-3


  19
    In the preceding table, the proportional weights of the fore-brain constitute a pro-
gressive series, beginning with the new-born infant, ascending thence to adult man, and
in due succession to the dog, the monkey, the horse, the seal, the elephant, and the bear ;
whereas one horse (a) follows after the pig, roe, cat, and the new-born rabbit.  To make
this series thoroughly instructive, we must note that the greater percentage of hemispheres
in the new-born infant is due to the slight weight of its cerebellum ; the same is true of
the  new-born  rabbit.  We must  note, furthermore,  that the other division of the fore-
    1 The total weight of the elephant's brain was 4,576 grammes ; the  brain-mantle
•weighed 2,906, the cerebellum 1,097, and the brain-trunk 575 grammes. 
258
PsycJiiatry.
brain, the lobus-caudicis stands highest in the series, amounting to 58 per cent., or more
than half of the entire brain-trunk.
    From the point of view of comparative anatomy, we shall find that the larger the
animal, the greater the weight of its cerebellum.   The elephant excels  in weight of
cerebellum, both relatively and absolutely,  doubling the weight of the human cere-
bellum, and  having a disproportionate  advantage  as  regards cerebellar percentage
over other animals : On the other hand, among more closely allied mammalian forms.
we find that there is a difference of twenty per mille (as regards cerebellar weight) be-
tween man and a young monkey, in favor of the former.   The new-born infant and the
new-born rabbit stand greatly in arrears, as compared to adult man, the infant showing
a difference of nearly fifty per mille (057).   The preponderance of the elephant as regards
cerebellar weights  sets his hemispheres  far back  in the series ; the seal, and even the
bear, going ahead of him.   The recognition of such broad differences as these seems to
me to be of far greater value than the consideration of refined minutiEe.
     In the above  table the frontal lobe is regarded as extending as far as the fissura
Rolando ; the parietal lobe thence as far as the occipital fissure ;  and the remainder is
put down as occipito-temporal lobe.  Comparing the development of these several divi-
sions in man, the monkey, bear, and dog, we find  that the frontal lobe is more highly
developed  in man than in the monkey ; that of the monkey stands higher in the series
than the frontal lobe  of the carnivora (dog and bear).   The parietal lobe is also less
developed in  monkey than  in man.   His larger occipito-temporal lobe is  due  to the
excessive development of the occipital portion.   The bear,  like all carnivora,  dis-
tinguishes himself  from man by the superior development  of the parietal  region.  In.
the new-born infant, this region is proportionately larger  than in the adult, a fact
which  can be explained by reference to the observation of Zuckerkandl, to  be  stated
in full hereafter.   Zuckerkandl states  that the growth (lengthwise) of  the median
portion of  the  hemispheres is furthered by the two cranial sutures (the coronal and
lambdoidal),  which are responsible for  the  longitudinal growth of  the skull  itself  ;.
but  that there  are no such transverse sutures favoring the unchecked development of
the occipital and frontal lobes.
     As regards the subcortical ganglionic masses from the thalamus on, we note that
man is inferior to  other animals as far  as the thalamus, and the mesencephalon in
particular,  are  concerned ; in the monkey the thalamic region stands higher than the
mesencephalon. The  greatest  proportionate difference is  found in  the  case  of the
medulla oblongata.  Its relative size in the cat is four times that in man.  This is due
in part to the larger quantity of connective tissue in animals, and to the excessive de-
velopment  of the posterior division of the brain-trunk as compared with the pyramidal
tract.
     Taking into account  the  difference quoted  above between  the brains of  two
horses, and remembering that  in another series  of  similar  investigations I found the
hemispheres—the brain mantle—in dogs and horses to amount to 67 per cent, of the
entire  brain  surface, we  may draw the inference that the difference, as regards brain-
weight between animals of the same genus,  is no less  than between various human
subjects.   Satisfactory results must, therefore, be based upon a very large statistical
collection.   The greater  difference will probably be  found between species  differenti-
ated by a process of selection.
     From Pflegers and Weichselbaum's statistics,  based  upon the
weight of  adult  brains,  we  take  the  following table  giving  the
absolute and proportional weights of the three grand  and primary
divisions of the brain : 
Weights of Brain-Divisions.             259
Weight (in grammes).				Per mille.	of the entire brain.		
u a	a 5	E _3	ai	1 o	S _3	c.a	
W-5	5 e	J3 4> 0	•5 = - 3	"IS pa a	1) 0	Brai trun	
1.373	1,092	148	133	795	108	97	From 390 soldiers of different nationalities, between the ages of 20 and 48 years. Average length of body = 171 ctm. = 5 ft. 6 in.
1,321	1,044	142	135	790	107.5	102	From 107 healthy (sane) men between the ages of 20 and 59 years. Average length of body, 166.5 ctm. = 5 ft. 4^ in.
1,189	936	131	122	787	110	103	From 148 healthy wo-men between the ages of 20 and 59 years. Average length of body, 156 ctm. = 5 ft. 1 in.
1,154	908	128	118	787	III	102	From 377 healthy (sane) women varying between 20 years and old age. Average length of body, i« crm. = 5 ft. 1 in.
   Pfleger insists  on the relatively greater  development of the
hemispheres in man as compared with those of woman;  the exact
relation being  as  795  to 787, on the scale  of  1,000.  Engel has
shown that this assigns the  larger cerebellum to woman during
the prime of  life.
   No inferences can be drawn  from the tables furnished above
as regards the composition of the hemispheres;  neither does the
literature  of the subject give us any clue either  to the  propor-
tional weight of the several lobes of the hemispheres, or to the
relative weights of the various subdivisions of the  brain-trunk.  I
propose, therefore, to supply this deficiency, and  to amplify the
physiological law  of brain-weights  by an analysis  of a large num-
ber of brains, which, though the brains of  insane patients, were
not characterized by any marked degree of atrophy.  The sub-
jects from whom these brains were  taken were all classified in the
official list of the Vienna Insane Asylum under the head of what
Griesinger termed " Conditions of  maniacal  excitement."   As
Pathologist to that institution  from the years  1866-71, I  had
occasion to weigh  733 brains, and from among these I  have the
notes of the brain-weights  of forty-six  male and  seventy female
subjects, who had  been classed under the heading  mentioned im- 
260
Psychiatry.
mediately above.  This  group of cases comprises the  heaviest
brains, both male and female.   For the sake of comparison, the
absolute and relative weights of these " heaviest " brains are tabu-
lated below.
   Adopting Bischoff's method, I have  also divided the cerebral
hemispheres into frontal, parietal, occipital, and  temporal lobes,
and have  ascertained the average weights of  400 frontal lobes,
235 parietal lobes,  135  occipital  and  210 temporal lobes.   A
more  rational division  could,  however,  be made between the
occipital and temporal lobes.

                       Weight in Grammes.
	4) • u S "5 '3 C i_	w s	i |	2 ? 23 ~	"3 .	'SI	Occipito-temporal lobe.	in 2	0 H	■ e s 0 a, ,-. it -C 1=5 d O	to C O Ph	ci ■ — SO. •c J S'o
Male Female .	1,383 1,221	1,085 954	148 135	148 132	450 400	251 2l6	383 338	81.36 74.84	26.40 23-74	9-03 7.6l	I6.58 14 23	6.2s 5-50
	Per Mille.										
	1 V	£ i 4) ^ X2	•5 g	"e3	5 a; <J 3,°	Occipito-' temporal lobe.	Lobus caudicis. Thai. opt.		e § T- oi 0	G 0	s tor -a 0 2 0
Male Female	785 781	107 IIO	107 108	415 419	231 226	352 354	583 595	188 188	064 060	118 112	044 043
   Wealth of cerebral convolutions is supposed to be an index of
the superior nutritive development of the human brain.   Facts
of comparative anatomy are not in accord with this view ;  for the
brains of the monkey, the dog, and the bear exhibit but few con-
volutions as compared with the brains of cloven-footed animals.
But we must remember too that from the ordinary psychological
point of view it is difficult for us to gauge the intelligence of an
animal; for those that flock together  and lead a social life, as it
were, must needs adapt  themselves to very different  conditions
from those that lead a solitary  life  in pursuit of  prey.  And, on
the other hand again, no  examination  has  been made  of  the
nerve-elements of the abundantly convoluted brains of bi-ungu-
lates, though I have shown that the vacant neuroglia-layer receives 
Convolutions Vary According to Formation cf Skulls.  261

a proportionately greater development  in  the  cortex  of  the  roe
than in that of the monkey and dog.  Furthermore, wc shall soon
have occasion to prove that the development of cerebral convolu-
tions  is governed by laws cf mechanics.  The convolutions are
crowded together in certain directions within the cranial cavity,
in consequence of which a check  is  imposed upon their free
development, whence it follows that no direct inference  can  be
made  from the wealth of convolutions to  the intelligence of  an
animal.  And yet we  must not fail to mention that within one
and the  same species a certain relation  does exist between the
number  of convolutions and  the  grade of intelligence.   Rudolf
Wagner  has insisted on the greater complexity of convolutions in
the brains of men of unusual  mental culture.   Great  difficulty u
encountered in the attempt  to give  a detailed account of the
cerebral  convolutions  of the  human brain.   Satisfactory results
have  been  reached by those  only  who  were  guided by simple
scientific principles.   Rudinger, who  has won especial  fame as
the most prominent technical anatomist of the peripheral nervous
system, was the first also to insist on such differences  as  exist in
fcetal  life between dolichocephalic  and  brachycephalic brains.
This difference in form is claimed to be distinctly recognizable on
both  the skull and the brain of a foetus four months old, just as
Fehling has recognized sexual differences  in the structure of the
pelvis at  this early age.  Rudinger lays special stress,  even at
this early period of brain development,  upon the  influence of
mechanical relations, and directs  attention not only to the skull,
but also to a characteristic tension of  the  dura, due to a  constric-
tion at the coronal suture in dolichocephalic skulls.  According to
Lucae this constriction extends  in the direction of the Sylvian
fissure as far as the parietal vertex, and results, in the adult skull,
in an excessive  (5 mm) thickening of the dura laterad of the
small  wing of the  sphenoid  bone.  This one circumstance im-
pedes the transverse  growth of the brain, and necessitates the
greater development of the brain  in the longitudinal direction.
    As regards sexual  differences Rudinger was able to conclude
from an examination of the brains of thirty males and  females,
that there is a difference in weight even in the foetus and  the new-
born child, in  favor of the male.  He adds, however, that Hecker's
statistics, which  are based  upon a larger  number of  cases, show
this difference to be far less marked.   Differences in the  develop-
ment  of the convolutions become apparent after the seventh or 
262
Psychiatry.
eighth month of embryonic life.  The same author holds that the
parietal convolutions are developed earlier than those of the oc-
cipital and frontal lobes ; that at birth the convolutions of the
frontal lobe in the female are particularly backward ; and that the
brain of the new-born female infant approximates more nearly the
fcetal type.  Furthermore, this lesser (retarded) development of
convolutions characterizes the female throughout life ; so that the
average wealth of convolutions is never as great in the female as
in the male.   Rudinger increases  the force of this statement by
saying that sex is a more powerful factor than mere individuality
in the development of the brain-surface. And yet,  as a matter-of-
course,  among female  brains  which  are  far above the average
there will be  many that exceed  in weight less highly developed
brains of the opposite sex.
    In one respect  the lesser wealth of convolutions in the female
is not at all a matter  of  sexual distinction ; but is due rather to
the  frequent dolichocephalic  formation  of  the  female  skull
(Welcker).  We shall see shortly that in dolichocephalic skulls the
course of  the longitudinal convolutions is in no  wise impeded.
The anastomoses,  which give rise to  an increased number of con-
volutions,  can be explained on mechanical principles ;  for in short
(brachycephalic) skulls the longitudinal convolutions  cannot be
extended to their  full length.   It was shown (page 14) that, with
the exception of the primary (typical) radiating convolutions, the
convolutions of  the cerebral surface were not to be explained  by
any laws of brain-evolution ; but that their development was gov-
erned by certain mechanical  laws, operating  even in early fcetal
life, and influencing the formation of the brain within its inflexible
bony capsule, the  skull.   These  mechanical laws have been dis-
cussed by  Henle, in more detailed fashion  by Ludwig Meyer, and,
as was stated above, by  Rudinger.  The  last-named  author has
clearly demonstrated the influence of dolichocephalic and brachy-
cephalic skulls upon the growth of  the brain during  foetal life.
The direction of the earliest convolutions is, therefore,  subject to
these mechanical laws.   According to Henle's simple hypothesis,
the fissures of the surface of the brain will  be developed in a plane
vertical to  those  shorter axes of the  skull which compress the
substance of the brain.  Thus in a narrow skull (and as such we
must regard  the dolichocephalus, since it  is not  distinguished by
absolute length from non-dolichocephalic skulls)  there will be but
little opportunity  for the development  of  transverse gyri,  which 
                Development of Convolutions.             263

would help to broaden the brain.  In brachycephalic skulls, on the
other  hand,  there  is a limit to the free development of longi-
tudinal convolutions, and the cortical surface will have to have its
duplicatures  develop  either in a transverse or in a vertical direc-
tion.   Inasmuch as the pia mater follows the fissures between the
convolutions, its expansion, and the nutrition of the brain will be
modified, as  Reichert stated, according  as the  cortex grows by
simple extension and formation of convolutions, or by the forma-
tion of duplicatures.   There can be no doubt about the influence
of these nutritive  and mechanical factors upon the development
of  the convolutions.   They cannot be  said,  however, to exert
any influence upon the functions of the cortex ;  for we have no
reason to suppose that the function of nerve-cells varies according
as they happen to  lie either on the top of a convolution or in the
depths of a fissure.
    I have endeavored to gather proofs for this mechanical theory
from a comparison, of the  forms of the  brain among  different
animals.   In doing  this  I was compelled to  invent  lines  of
measurement which  differ from  those  which  have  come  into
general use through Welcker's investigations on the human skull.
Owing to the differences  between  the  skull of man and other
mammals, I  have  selected "lines"  connecting  other but more
practical  fixed points than those of Welcker did.   The brains  of
carnivora, of the fox, the  dog, the cat, and  the lion, can well be
compared with one another.  The skull of the fox is the only one
which does not come within the order of brachycephalic  skulls,
for it  has  an index of yy  <?0, which  expresses the  relation of its
transverse to its longitudinal diameter.   The dog, on the other
hand,  has an index  of  85, and thus falls within the limits  of
human brachycephali.1  The cat and the lion exceed the latter,
their skulls  having transverse indices  of 97.2  and  98.7.   This
peculiarity of structure is evident in the four-cornered  appearance
of  the cat's skull.  In  keeping with  these variations in skull-
structure, we find, as we ascend in the series of carnivora, a greater
and oreater  development  of  transverse convolutions.  The fox
possessing the (relatively)  narrowest  skull, exhibits  a  brain  in
which the longitudinal fissures  are  most abundantly  developed.
The  dog, again,  possesses  transverse  convolution-loops (Win-
    1 Those people who possess crania with a cephalic index of 80 and above are called
brachycephali ; those with a lower inde* are dolichocephali.  For a succinct statement
of these relations,  see Huxley,  "Anatomy  of Vertebrated Animals," Am. ed.,
p. 420.—S. 
264
Psychiatry.
dungsschlingen) and transverse anastomoses.   But Leuret was the
first  to demonstrate that in the brains of the cat family all the
longitudinal fissures  are interrupted  by  typical  anastomoses
vertical  to these  fissures.   The  anastomosis  connecting  the
superior margin of the first longitudinal arch with the second is,
in fact, known as the " cat-fissure " (Fig. 9, between arc I. and arc
II. ;  also p. 14).  These anastomoses, transverse, as they are, are
crowded, as it were, from the depths of the cortical fissures to the
surface by a sort of longitudinal stenosis.   The brains of the seal
and  the elephant are  hyper-brachyccphali;  for  their  transverse
diameters are greater than  their longitudinal diameters.   In the
seal, the former (the transverse) bears to the latter the proportion
of 118.8 to 100.  In a young elephant the relation is 128.3 to 100,
and in an old elephant, 123.3 to 100.   In the  seal the  transverse
axis  of the brain is  not great enough to compensate  for  the
extreme shortness of  the longitudinal axis.   This compensation
is  effected, however, in the anterior portion  of the brain-mantle,
by the unusual height of the brain.  This method of compensation
is  not feasible in  the  occipital  region, where the  cerebellum
presses from  below upwards against  the  occipital lobe.  In con-
sequence of the  shortness  of the  longitudinal  diameter of  the
seal's skull, its  olfactory lobe  cannot occupy a longitudinal  posi-
tion, but is forced to lie in a vertical direction against the anterior
surface of the brain.
   For the same  reason the Sylvian fissure in the brain of a seal
takes a vertical course, and not its customary oblique-longitudinal
direction.  As a result of  the brachycephalic  nature of'their
skulls, the operculum in animals curves downward (Fig. 7) instead
of taking a straight longitudinal course ; in the seal it has not even
an inferior longitudinal margin, and like a wedge with its point
downward, pushes its way in between  the ascending limbs of the
Sylvian fissure, thus  making a  heart-shaped formation of this
fissure.
   The skull of the seal, if not  more convincing than the other
facts of comparative anatomy alluded to  above, offers the best
illustration in favor of the mechanical theory of the development of
brain-convolutions, as against any theory which would  ascribe
their special formation to purely embryological laws.   In the case
of the elephant, the necessary result of his brachycephalic skull,
i. e.,  convolutions vertical to the longitudinal axis of the cranium,
was recognized by Leuret, who declared that the elephant's brain 
Zuckerkandl's Investigations.            265
had three transverse central gyri instead  of  two as in man, and
two  transverse  central  fissures  instead  of  one.  A  transverse
anastomosis between the  superior and inferior parietal lobules
back of the fissure of Rolando, might lend a similar  appearance
to the brain of man.1  In this connection the recent publications
of Zuckerkandl will be  of  great interest  to  us.  This  author  at-
tempts to explain why it is that the  gyri at the frontal and the
occipital ends of the human  brain  are  the most tortuous, the
narrowest, and most freely supplied with anastomoses, while those
occupying the middle portion  of  the cranial cavity are broader,
and develop more freely in a longitudinal direction even though
they are cut across behind the  coronal suture by the  sulcus cen-
tralis—one of the typical fissures which is entirely independent of
all mechanical influences.  As we had occasion to  remark above,
there is  no impediment to the full  longitudinal growth  of the
median portion of the  skull.  The synostoses  of  the transverse
coronal  and  lambdoidal sutures  contribute greatly  to this end.
In this region the skull  is broadest also, and  the convolutions can
therefore develop freely in both the transverse and  the  longi-
tudinal diameters.   In the frontal  and  temporal region of the
hemispheres,  however,  the convolutions  are necessarily crowded
more closely together.   A more liberal longitudinal development
is characteristic  also of the anterior temporal convolutions,  for
these convolutions lie within the middle  cranial fossa,  where the
growth of the brain  is in no wise impeded.  Zuckerkandl has dem-
onstrated, moreover, on  pathological akroccptiali, that the  in-
fluence of the stenoses  of the skull, due to the synostosis between
the lateral portions of the coronal suture  and the suture between
the small wing of the sphenoid bone and the  orbital  portion of
the frontal bone, was manifest in the greater tortuosity of, and
the larger number of transverse anastomoses between, the corre-
       o
sponding convolutions.  He demonstrated,  furthermore, that, in
consequence of the early synostosis of the sagittal  sutures in doli-
chocephalic skulls, so prominent a transverse fissure as the sulcus
occipitalis internus has its margins torn asunder  lengthwise by the
development  of longitudinal convolutions, which seem by trans-
verse pressure to be crowded out  of the depths  of this sulcus.
    Even L. Meyer fully recognized the importance of mechanical
relations.  As a result of the sagittal stenosis in the occipital
reo-ion of a skull, which he examined, he  had occasion to observe
1 Anzeiger der Gesellschaft der Aerz'.c, Wien, 1876, Nr. 29. 
266
Psychiatry.
that the convolutions  underneath covered one  another after the
fashion  of  lids.  To this lid-arrangement  he applied  the term
operculum, but it is needless to say, in view of the  excellence of this
author,  that he did not think this an instance of an approach to
the ape-type.
    On pp. 240-243 we dilated upon the intimate relation between
nerve-nutrition and the peripheral end-organs, v. Gudden, in a long
series of experiments, has proved this relation to exist in the case
of the central nerve-fibres.  This investigator found that if means
are taken to deprive a new-born animal of various  sensory  im-
pressions, by uniting the opposing surfaces of  the  nostrils, by
producing  artificial symblepharon, etc., there  would be a  marked
arrest in the development of certain portions  of the brain.   In
regard  to the sense of smell, he found that the olfactory nerves,
the bulbus olfactorius, and the medullary substance of the olfac-
tory convolutions arising from this bulbus (pp. 21,41, yo) remained
relatively undeveloped. A compensatory thickening was noted (on
a  frontal section of the skull) over the atrophied portions of the
brain ; it was observed also that neighboring parts of the brain  had
pushed forward to  fill this  void.   This arrest  of development
became still more marked,  if  instead  of  excluding  peripheral
stimuli  only, the nerves themselves had been destroyed by scrap-
ing out the mucous-membrane, and  extirpating the labyrinth, of
the  nose.  But the bulbus was not affected either by the above
experiment or by the unilateral extirpation of the olfactory lobe.
This latter statement  I am  inclined to doubt, from a knowledge
of the  laws of nutrition ; for the medullary substance from  the
bulbus undergoes atrophy, and this substance lies upon the basilar
surface  of  the olfactory lobe.  But the atrophy need not be very
apparent, for  the  medullary fibres  from the bulbus olfactorius
constitute but a small  portion of those fibres which enter into the
depths  of the lobus olfactorius.
    Furthermore, we have it on the authority of Gudden that  the
anterior commissure does not diminish in volume after the extir-
pation  of the  bulbus  olfactorius, for  its nutrition is dependent
upon the cortical substance of the olfactory lobe.   The latter
statement may serve to demonstrate the dependence  of nutrition
upon the central gray  substance.
    The anterior commissure does not begin to atrophy until the
lobus olfactorius is removed.  This Gudden accomplished at the
same time  that he  removed the entire hemisphere.   As a result 
v.  Gudden s  Experiments.              267
of this extirpation there was atrophy also of the corpus callosum,
for the nutrition  of the  latter is  dependent  altogether  upon
central nutritive influences—that is,  upon the cortex.  The truth
of this is demonstrated, moreover, by partial extirpation  of the
cortex,—by the removal  of an anterior lobe, in consequence  of
which there is atrophy of so  much  of the  corpus callosum  as
corresponds in length to the resected portion of the cortex.
   Sewing up the eyelids of a new-born animal  (thus excluding
peripheral stimuli) was followed  by  moderate  atrophy. of the
optic nerve, optic tract, and of the anterior corpus bigeminum  of
the opposite  side.   The  corpus geniculatum internum remains
unaffected; while the external geniculate body, lying in animals,
upon, and being confluent with, the  thalamus (pp. 32 and 33) was
not  a subject of  observation.   Extirpation  of the retina was
more effective ; it resulted in gray degeneration (possibly also  in
arrest of  development  of the medullary  sheaths)  of the  optic
nerve, and the opposite optic tract; also in a  more  marked
atrophy of the corpora  quadrigemina.  In rabbits which had been
thus  mutilated, the internal  corpus geniculatum and the  hemi-
spheres were not affected.  There was atrophy,  however, of the
tractus  transversus pedunculi (Fig. 15, T.).  Extirpation of both
eyes even was not followed by a diminution of  the hemispheres,
thus proving again the  central nutritive influence of the cortex.
It was  only in doves that Gudden observed diminution  of the
hemispheres in addition  to  atrophy of the optic lobes, following
upon extirpation  of both eyes.  This is particularly instructive,
for the atrophy must be attributed to fasciculi of the optic tract
in birds, which pass by way of the pes pedunculi into the  hemi-
spheres without connecting with the optic lobes.1  We may infer
from this, and from the atrophy of the superior corpora bigemina,
or of the  optic lobes respectively, that the exclusion of peripheral
nutritive  stimuli does not tell upon  the nutrition of more distant
gray  substance, which  happens to lie beyond the  (to  it) nearer
gray  nodal masses in which the fasciculi terminate.
    In addition to showing the effect of the removal of the cortex
upon fibres of the corpus  callosum, Gudden has demonstrated the
central nutritive influence by reversing the plan of operation and
extirpating the superior corpora bigemina.  He found that just
as  in peripheral extirpations,  so here, though in  an  opposite

    3 The optic lobes, though situated more latero-ventrad, are the substitutes in birds
of the corpora quadrigemina. 
268                      Psychiatry.
direction, the  operation was followed by a distinct, though less
marked, arrest in the development of the optic-nerve tracts.
   In an important monograph, Flechsig has discussed the influ-
ences of peripheral portions of the  projection-system upon the
development of more  centrally situated members of this system.
Flechsig has based his studies upon  certain phenomena, to the
scientific value of which  I was the  first, as he acknowledges, to
call attention.  In the brain of  the new-born infant we find, as was
well known even to previous investigators, that certain medullary
areas are gray instead  of white, which is due simply to  the lack
of development of medullary sheaths.  Inasmuch  as I was able
to perceive the gray appearance of the pes pedunculi in the  new-
born, and the distinct white color of the fasciculi in the tegmentum,
I inferred that these phenomena were related to  the  secondary
development of cortical functions, which must necessarily be pre-
ceded in time by the functional development of subcortical masses.
But  the pes pedunculi  (pp. 28 and 29) is intimately related to con-
scious actions (Bewusstseinsleben), whereas the tegmentum  is  re-
lated to those subcortical  functions which go on undisturbed after
the removal of the fore-brain.  The maturing of these tissues seemed
to me,  therefore, to keep pace with the occasion of their first
functional  manifestations.  Flechsig, in his thorough-going  re-
searches on the  development  of the medullary substance, has
worked out this idea in all its details, and, as we must acknowl-
edge, has left  little for others to do in this matter.   Flechsig
discovered that the progressive development of medullary sheaths
sustained a definite relation to the length  of the  foetus.   He
proved, furthermore, that  the  medullary sheaths developed  from
below upward, and that  in the spinal cord  and  oblongata the
white substance became apparent in foetuses only twenty-five cen-
timetres in  length, appearing earliest in the columns of Goll and
Burdach.  This again is  instructive as regards  the functions of
these parts ; for  the centripetal nerve-tracts  are the keys which
start the mechanism of the entire central-nervous system, and  we
thus see that the peripheral nutritive influence is indicated by the
special order in which nerve-tracts acquire their white substance.
    Next in the order of development come the anterior  columns
of the spinal  cord, which turn white when the foetus has reached
the  length of from thirty  to thirty-two centimetres.   At this time,
the pyramids are still gray.  These two facts taken together simply
mean that reflex movements are the  immediate outcome of the 
Flechsig s Investigations.              269
development of  sensory tracts, but that the tracts along  which
secondary  cortical  impulses are to be transmitted are not yet
matured.   The peripheral  nerves  acquire  thc'r white substance
equally early.   The optic nerve, which  resembles in structure the
central  white  substance, its fibres having no sheath of Schwann,
undergoes changes " within two or three days of extra-uterine life "
(the length of  the body being but twenty-six centimetres),  which
far exceed those changes which would  take place during a much
longer period of intra-uterine life.  This shows most distinctly that
the nutrition of central nervous tissues  is greatly aided by sensory
stimuli. Such stimuli are conveyed to a certain extent by the pos-
terior roots of  the spinal cord and the higher functionally similar
fibres during intra-uterine life,  but the influence of light  is not
felt until after birth.  According to Flechsig, other nerve-tracts
in addition to those in the spinal cord turn  white during the intra-
uterine  period.   The  following order is  observed :  The oblongata,
with the exception of the pyramids ; the cerebellum, and first the
medullary substance of the vermis ; the tegmentum cruris; and next,
those bundles  of fibres which lie between the large ganglia, and
which, judging from Flechsig's plates, correspond to the radiations
from the thalamus and mid-brain.  These  are chiefly centripetal
nerve-tracts (pp.  197-204).  The white substance appears  finally
also in the parietal and occipital lobes.
   After birth, when the body has attained to the length of sev-
enty-six centimetres, white  nerve-bundles  appear in  the pes
pedunculi and the pons.   " Soon, too, radiating white fibres, which
pass from the brain-axis to the occipital and temporal lobes, lend
a white appearance  to various  marginal  areas of  these lobes."
These  radiating  fibres  were  determined by  the  anatomical
researches  of Gratiolet and myself (p. 48), and by the experiments
of Hitzig and  Munk (pp. 146-149), to be centripetal nerve-tracts.
" Not until several months after birth  does the white substance
appear  in the frontal lobes,  and not until  the end of the  fourth
month  do  these parts  become  as white as they remain  through
life."
    The  secondary  development of cortical  motor  functions is
entirely in  keeping with the late development of those medullary
tracts which are engaged in the  performance of these functions.
Flechsig was also able to observe that the central cortical area
was the first  to  turn white, and that  in proportion as the radia-
tions from the  brain-axis  took  possession  of  the cortex, the 
2 70                      Psychiatry.
medullary substance  began  to  spread along the lines of the
association-fibres lying within the cortex.  This order of develop-
ment marks the functional growth  of  the  cortex; for the func-
tions of  the association-fibres are necessarily secondary to the
stimuli  from the outer world, conveyed to the cortex by the radi-
ating nerve-tracts from  the brain-axis.   Upon the basis of the
simultaneous or successive appearance of white substance, Flech-
sig has formulated the  following  axioms regarding the relations
of the super-imposed divisions of distinct medullary systems:
    I. Systems of  fibres situated  one  above  the other, which
develop at very different periods (several months), are not directly
connected, one with the other.
    2. Mere juxtaposition of  bundles which  do not acquire their
'white  substance simultaneously is not  sufficient proof  of  any
anatomical connection between such  bundles.
    3. Those fibres which are connected with higher cerebral cen-
tres develop  latest.
    In the clinical chapters of  this work we shall have occasion to
discuss  the diagnostic value of Flechsig's methods of  investiga-
tion. 
APPENDIX.
                        THE MECHANISM  OF EXPRESSION.

    Through  such movements  as are involved  in  expression  we  obtain a  clue
to  the  inner  mental  life  of others.   Up  to  the  present  time  we  have  con-
sidered  movements in their simplest relations, just as we discussed in the simplest
manner possible, in the second section of this volume, the formation of the  processes
of association and  induction, which are at the foundation of the whole cortical mechan-
ism.  We proceeded in  that chapter on the supposition that the cortex initiated voli-
tional, causal, conscious movements only ; we distinguished, according to their purpose,
between repulsive and aggressive movements, and concluded that the motives for such
actions were supplied by  emotions which were in turn intimately connected with move-
ments of  the  muscular apparatus of blood-vessels.   We established also biological
relations between movements and the preservation  of animal  existence.
    The laws  governing  our every movement are  obscured  only by the phenomenon
of free will (page 172). If we attempt to study our movements in all their complexity,
we shall discover that there are many which in other persons seem to be purposeless, and
in ourselves, unintentional, or unconscious.  We are concerned with  an order of move-
ments which are not to be explained on the score of expediency ;  and yet, since these
superfluous movements are entirely similar in many people, we may  hope to formulate
the laws governing their  performance.
    This  surplus of movements comes  under the  head  of physiognomical  phe-
nomena, which we may  consider  secondary  to that large class of (conscious) actions
and movements that have a distinct  purpose.   The  old  prejudice about  the possi-
bilities of inferring the peculiar and special activity of the brain from the configuration
of the face  or other parts of the body, (and that not by reason of  knowledge which
every one can acquire but, as Lavater presumed to say,  by dint of a special talent),
does not deserve serious consideration.  The  special formation of  the face is the result
of a mechanism which is entirely independent of the brain,  and which, as far as the
bony structure beneath is concerned,  may  be modified by morbid  conditions which
exert an influence upon the  nutrition of the whole body.
    I shall  have  occasion  in a later  portion of this  work to refer to such morbid
types of  features as  admit readily  of a  simple  explanation.   But as  for  the
movements constituting  the mechanism of  expression, they are comprehensible to all,
since they are  the same in others as in  ourselves,  and are the regular accompaniment
of our thoughts and emotions.   It will be my object, therefore, not only to study the
change of physiognomical  expression of the individual, but  also  to regard each such
individual as himself a physiognomist.  We  shall have to deal with  a  large number
of intelligible, though partly unconscious, and frequently delusional inferences, which
are based  chiefly upon secondary associations.
    It is characteristic of movements  of expression that they not only  have no definite
aim, but that  they are  performed unconsciously.   But unconscious  performance of
                                       271 
272                            Psychiatry.
 such movements does not necessarily imply that they are effected only by a subcortical
 motor mechanism, for the original stimulus for such movements is included within the
 mechanism of association, and this mechanism may operate, as was  stated on  p.  247,
 below the threshold of consciousness,  and may transmit motor impulses to  the pe-
 riphery though the cortex be not in the state of partial  wakefulness.  And then again
 all cortical movements, and, in fact, all cortical functions are secondary ; the question,
 therefore, arises, whether movements of expression also have a subcortical origin.
     Later on the reader will be told that,  in accordance with Flechsig's investigations,
 the subcortical centres cannot be made subject  to cortical inhibition, until the  pre-
 viously gray fibres of  the cortex have attained functional maturity, *.  e.,  until they are
 enveloped by medullary sheaths.  Subcortical  movements are effected along tracts
 which have  acquired  their white  substance earlier or during the intra-uterine  period.
 The primary reflex movement underlying closure of the eyelids we know  to be an
 experience of  the very earliest period of  infantile life (p. 156).  Possibly we  can, at
 this same early stage, discover the phenomena underlying the mechanism  of expression.
     In the first instance, then, we may argue that since, in the adult, the movements
 of expression vary with the emotions, these movements must be  either of an aggres-
 sive  or repulsive character;   but in order  to substantiate this statement  we must
 determine which are aggressive and which repulsive.  We will find, with regard to the
 child in particular, that all physiognomic phenomona come under these two heads.
     Life  begins with an inspiration,  which is the  first instance of the appropriation of
 external resources through muscular action.   This inspiratory act dilates the  cavity of
 the thorax.  The respiratory movements have a great physiognomical value.   Charles
 Bell, who up  to  the  time of  Darwin was the only scientific physiognomist,  seems to
 have appreciated this fact, for he speaks  of the facial—the nerve of mimical expression
 —as the respiratory nerve of the  head.  The second  act, that of sucking, is also  one
 through which the child draws upon the  resources of the outer  world.   This sucking
 movement is effected by inspirations, and  by the dilation of another body-cavity ;  it is
 a movement  of aggression.  It is  not based upon a reflex mechanism started by tactile
 stimuli.   But it is more probable that the sense of smell, and possibly  also the sense of
 taste, act  as reflex stimuli.  The participation of  the latter sense is probable from the
 fact that  while a child will not begin to suck at a breast which secretes watery milk,
 it  will do  so as soon as the milk is of normal concentration.  Some maintain, also, that
 a solution of sugar put upon the nipples will make a child suck more vigorously.
     Sucking dilates the stomach just as  inspiration  expands the thorax.  In inspi-
 ration,  one   of  the  body-entrances—the  nasal cavity—is  dilated.   In  sucking,
 the  cavity of  the mouth opens   and dilates.  The acts of sucking and  breathing
 together  produce an  apnoetic phase of  nerve-respiration, in  consequence  of  the
 formation of blood and of  oxydation.   At the beginning the child,  like an animal,
 is  guided  by  its  sense of smell   only,  and  at that,   imperfectly,   for  it lacks  the
 power of  locomotion.  Its tactile sensations are blunt, as Soltmann  has insisted  ; it
cannot see,  for during the first  three  weeks  at least  its eye oscillates hither  and
 thither, and it certainly has no perception  of space.
     Reflex movements can be well  demonstrated on the upper  extremity.   Stroking
 the palm of a child's hand produces closing of  the hand ; stroking the dorsal surface
produces  extension of  the fingers.   But there are no reflexes of the  upper extremity
which  respond regularly to stronger stimuli.   This is due, in all probability,  to  the
marked irradiation of all impressions received into  the subcortical  gray substance.
The chief reflex movement is screaming  (Schreien), an irradiation upon the expiratory
nerves, during which  act the  expiratory movements may become irregular, and  may
even be inhibited.  Screaming, a repulsive reflex movement, followed by a narrowin"
of  the thoracic cavity, is not attended by  crying.   But through irradiation screaming is 
Appendix.                             273
connected  with  another movement of repulsion,  with closure of the  lids, which
narrows  another body-cavity.  Bell  connected closure of the lids with respiratory
movements.   He thought  that the former compressed the eyeball, and thus prevented
the hyperaemia which might  result from the pressure of expiration.  But a condition
of hyperaemia would  be  produced  by laughing also, which  is  an aggressive reflex
action ;  and yet there is no active closure of the lids accompanying that act.   For this
reason it will  be  better to suppose that closure  of the lids is  part  and parcel of the
repulsive  reflex  per se, and is calculated to  screen  the  external world from the
individual, instead of putting him, as it were,  into  possession of that  world.  Spas-
modic closure of the lids, however, exert  a pressure  upon the lachrymal glands, and
starts the secretion of tears.   Later in life tears are started by emotions of a repulsive
character, without  mechanical pressure being exerted.   But this is a phenomenon of
association.   Since the painful  impulses leading to  repulsive reflex  actions  have
become associated with stimulation of the nerves governing lachrymal secretion, the
motive of such a reflex act  of  repulsion  will  (through  the mediation  of its cortical
image, which has  become part  of the mechanism of association) suffice  to  start
secondarily the secretion of these glands.
     In  consequence of irradiation,  and  the  lack of cortical  inhibition  upon the
subcortical gtay  substance, we find in the child imperfect mimical expression ; and
in its stead we have pronounced spasmodic contractions, which, according to the spirit
of the observer,  are interpreted either as  laughing or  ciying.   The same  is true of
those afflicted with dementia paralytica.   There is undoubtedly nothing  akin  to
laughter in a  child under three  months of age, although certain contortions of the
muscles of expression  have been so interpreted.  Indeed the question arises  whether
the  union of  laughter and  pleasurable  emotions be  not the  result  of  imitation.
Laughter is  far  more  conventional than crying, and in the  adult does by no means
point to an aggressive emotion.   Not infrequently it is the concomitant of psychical
pain.
     In  determining  the character  of the mechanism of  expression, we have next to
consider whether movements of aggression are not associated with the  dilation of the
portals and cavities of the  body, and those of repulsion with the narrowing of the same.
Pleasurable emotion is attended by exalted respiration,  and, in the spasm of laughter,
may lead to a considerable increase in the number of respiratory movements.  Painful
(hampered) mood diminishes the number  of  inspirations, and Charles Bell observed
very correctly that sighing is a deep inspiratory movement, which is performed by way
of compensation  for  the  preceding  diminished respiration, and in response to the
dyspnoetic stimuli  acting upon  the  respiratory centre.   The respiratory spasm in
crying and sobbing also increases, it is true, the number of respirations,  and to this we
may ascribe  the  relief  we get  by crying during  painful  emotions.   Two  popular
symbols may well be contrasted :  the  crescent shape of the mouth, with its convexity
looking  downward, serves as  the expression  of happiness ;  the crescent, with  its
convexity looking  upward, denotes sadness.   The crescent, with its. convexity down-
wards, may be taken to be the result of the contraction of the levator ala nasi, which
helps to  dilate  the nostril.   And, on  the other hand, the muscles that depress the
corners of the mouth, also depress the nostrils.   The firm closure .of the lips is due to
the action of the  orbicularis oris, the musculi incisivi, and the  levator menti.
     During a painful emotion the eyeball seems sunken within the orbital cavity ; in an
ao-gressive mood  it seems to push outward as if  to seize upon the world beyond.  With
the increasing pleasurable emotions of laughter, the cavities of the face widen still more.
The nostrils bulge  out, the lips separate, the teeth show, and possibly the entire cavity
of the mouth  may be widely dilated. 
2 74
Psychiatry.
    I wish to remark at this point that the expressions of  emotion are too manifold to
allow us to suppose that each has distinct muscular groups of the face at its disposal.
The unprejudiced observer may be in doubt as to the meaning of extreme (exceptional)
expressions of emotion.  Showing of the teeth, and raising of the nostril may accompany
the emotion of fury,1 which is any thing but a pleasurable emotion.  These are not the
result of reflex action, but of cortical stimuli acting as secondary presentations.
    Space-vision on the part of the child excites movements of aggression which aim at
the possession of the things it sees ; but as it lacks the power of locomotion, it has no
conception of distances.  These aggressive reflexes of the upper extremities are no more
coordinated in space than the movements of the eyes are before the child has learned to
see.  The  aggressive emotion is attended by great frequency and irregularity of respira-
tory movements, and through  irradiation these movements become  general, leading
to a  tossing of the whole  body,  to kicking with  all  fours,  and to  cutting  of
grimaces.   But  these movements, though extravagant, are  not spasmodic ;  we must
look upon them  as the result of cortical impulses which have been interfered with by the
process of irradiation.
    As soon as movements of aggression have taught the child to take hold of things,
it is evidently under the impression that it is living in a world of sweets ; it takes every
thing to the mouth, and licks it.
    A later aggressive movement—kissing,—like the first sucking movements, is prob-
ably based upon the act of bringing an  attractive object to the mouth.   This latter
movement is clearly dependent upon a powerful secondary presentation aroused by its
impressions, just as the sucking movements during sleep in early life denote secondary
presentations excited in the course of dreams.   At this period, the acoustic nerve  also
takes part in reflex impulses ;  the child that hears  others speak, or perceives other
sounds and noises, has the desire to bring forth the same sounds  and noises  (p.  208).
As its cortical functions improve, it develops the secondary idea that the sounds which
it brings forth are similar to those of ordinary speech.  In all aggressive movements it
overestimates the possibilities of its powers ;  it tries to force things that are too large
into its mouth, to take hold of things that are beyond its reach, and places its  incobrdi-
nated sounds on a par with the speech of adults.  Experience, and an  improvement in
the power of imitation correct  these  false conclusions.  As  soon as the child  has
reached that age at  which all cortical fibres have acquired  their white  substance
(Flechsig), the purely reflex movements and those due to irradiation diminish in num-
ber.   The Darwinian doctrine that ideas are inherited and are not the result of  per-
ception and association, that  movements,  even mimical ones, are the result of innate
motives, and have nothing to do with  imitation and early reflexes, can hardly be ap-
plied to man.  Not even his upright gait, which is surely a universal form of move-
ment, is innate in man ; it is acquired with difficulty only through imitation and cortical
coordination.
    I shall have to  refer again and again in the discussion on the pathological forms of
physiognomical impulses to the many excellent observations of Darwin, whose views are
based upon a larger number of facts than has been at the disposal of other  physiogno-
mists.   But I must speak first of a few fundamental  principles.
    In the child the expressions of emotion may vary very much.  Under the influence
of the apnoetic effect of the functional hyperaemia attendant upon pleasurable emotions,
there will  be movements  of aggression, bespeaking the force of the child's own  per-
sonality, or there will be spasmodic movements of repulsion (due to irradiation),  such
as screaming and crying.   All these movements of expression, whether due to irradia-
tion or not, despatch sensations of innervation to the cortex, which (sensations) are there

             1 Its mechanism will be referred to in the second part of this work. 
Appendix.
275
turned  into special  "memories" and  serve  later on as impulses starting  the  entire
groups of movements which are involved in expression.   Consequently  these  move-
ments of expression result primarily from stimulation  of  subcortical centres, just as
simpler forms of reflex movements served as the foundation upon which the structure of
more complex conscious movements is raised.  As soon, however, as these irradiatory im-
pulses,  which excite the mechanism of  expression, are put under the rule  of an  organ
of motor coordination (the cortex), they acquire secondarily a higher value as psychical
factors  of expression.  In the child pleasurable emotions result in general movements
of the entire body ;  and even in the adult, who dances for joy or performs other extrava-
gant  movements, we  have a repetition of these primitive mimical movements  of the
child.   That a state  of excessive pleasurable  emotion may pass into a  condition of
maniacal  excitement,  as the result of a dilatation of the arterial network of the  brain,
or that  a state of pleasurable  confusion  may end  in  a transitory swoon (the probable
result of  subcortical vaso-motor stimulation), has been demonstrated by Darwin.
     Wundt says correctly of animals that their speech consists of so-called sensory sounds,
and this is true of children before they have acquired the faculty of imitating syllables.
In the adult also there is  something akin  to  this particular expression of emotion in
the meaningless sounds and notes which  are uttered in exultant shouting.   A number
of special forms of movement, which are  associated in the child with pleasing or painful
emotions, and are the expressions of aggression or repulsion, may be recognized  in the
features of the adult,  and  may be easily traced  back to the innervation  sensations of
infantile movements.  A pouting of the lips (russelartige Mundstellung), as in sucking,
is associated  with the expression of contentment, of approval, and  may  be observed
also during the communication by another  person of a pleasing thought or  argument.
On the other hand,  an expression resembling faintly that of weeping may be  noticed on
the receipt of a disagreeable communication or of one from which the listener dissents.
It is not probable, however, as Piderit would have us believe, that these peculiarities
of  expression  are connected  with secondary association of a sweet or  bitter  taste.
Our  " types " of expression are not  precise enough to allow of such an exact interpre-
tation.
     As regards  the movements of  the  arms,  a pleasurable aggressive  emotion may
give  these movements the character of an embrace, of an intention to seize upon the
desired object, although the object exciting such emotion may be far beyond the reach
of  the arms.  A repulsive emotion is attended by a repulsive movement  of  the  upper
extremity, even though there be no object near by to be repelled.  Darwin  states that
the overflow  of  psychical excitation, even such as may originate in our thoughts, and
which gives rise to a change in our features, is  equivalent to an excess of nerve-force,
which is exhibited in certain typical forms of expression.  This excess of nerve-force  we
can define  quite  accurately.  It is either the result of present impulses, or of cortical
images associated with these  impulses,  and is  dependent either upon irradiation or
upon association.  Through irradiation this excess of nerve-force may spread beyond
the limits of consciousness, and may involve  movements in nowise associated with the
engaging thoughts  of the moment, as is well illustrated in the  irregular movements
of an orator who has lost the thread of his argument.  On the other hand,  again, the
impulses may represent  nutritive  processes in allied  association-tracts, the  functional
activity of which is exceeded in intensity,  and is inhibited, by the prevailing impressions,
or by the conscious  and strong, because  purposeful, train of thoughts.  Of this func-
tional activity of secondary association-tracts consciousness takes no  cognizance ; it is
relegated to the domain of what Fechner calls  partial sleep, and yet may be marked
enough to be expressed by associated, though unconscious, movements of the features.
     On this point Darwin gives a number of apt illustrations from his own  experience 
276
Psychiatry.
and that of other authors.   In regard to the emotions, it is evident that  fear is associ-
ated with movements which would accompany the actual experience of the evil feared.
A person fearing an accident will wring  his hands  as he  would have done if the acci-
dent had actually  occurred.  Rage is accompanied by movements  which would be
useful  in destroying the obnoxious object ; by biting movements, by showing of the
teeth, by a pounding with the fist, and by movements such as those of treading upon a
disagreeable object  and trampling it under foot.  These movements are the expression
of allied (secondary) associations,  and  are  frequently not  recognized  as conscious
movements.
    An  equal  interest  attaches to  other physiognomical movements which are the
expression of allied associations, of parallel presentations attending  any quiet  train
of thought.  A vulgar man, or one lost in fruitless thoughts, who scratches his  head,
acts  as  though he  were experiencing  a  familiar uncomfortable sensation.  Gratiolet
remarks, that a man who rejects  a proposition will shut his eyes or turn away his face ;
he acts as though he did not or would not see the thing ; but if he accepts the propo-
sition, he will, by nodding, bring his head nearer to the speaker, and will open his eyes
widely,  as if he clearly saw the thing.  Duchenne remarks, that  a person in trying to>
remember something often raises his eyebrows, as if to see it.1   Engel calls attention
to the fact that a person who suddenly  finds his thoughts checked  will walk slowly or
come to a complete halt; he will move on again, as soon as his thoughts  move.
    From the above we see that physiognomical expression is chiefly a matter of sec-
ondary presentations, which are  evolved, like dream presentations, from  the condition
of partial sleep ; and that expression is  dependent altogether upon the  simultaneous
excitation of such  secondary presentations as are associated  with our emotions or our
thoughts.
    I have a few words yet to add in regard to the  emotions, of which I have spoken
repeatedly.   I discussed their mechanism in the preceding chapter, but for the sake of
simplicity did not go into details.
    We  had contrasted only the emotion of  passive grief with  that  of  joy and con-
tentment.  The emotion of  passive grief is accompanied by ideas of repulsion in regard
to the outer world,  but  not by active impulses of aggression.  This  emotion is
expressed by a narrowing of the cavities  of the face and by a  dearth of movements—a
failure to assert one's own  personality among the objects of nature.  The corrugators
draw the skin under the brows inward, as if to form a roof to shut out the light ; the
lips are pressed together, the nostrils are depressed, for respiration is weaker, and the
features are immovable, in consequence of a monotony of  the thoughts.   The expres-
sion may become complicated through the united action of the inner  fasciculi of the
frontalis and the corrugator bringing into prominence the  so-called wrinkles of  grief.
The inner end of the eyebrow will be raised, and we then get an expression which, if
dependent upon allied associations, may be interpreted to mean that the afflicted  one
is looking up at his  fate or for help.
    Passive grief is marked by inattention ;  the emotion of fear, by greater excitement
and attention.  In grief there is  nothing like the defensive cry brought on by fear.   In
fear the eyes are kept open, and flight is the active expression of such  fear.   Move-
ments of flight maybe started by allied associations, even in the absence of real danger,
and in spite of the  will of a person.   Fear is probably the neurosis  of  a subcortical
centre  (of  the  oblongata),  excitation  of which defies cortical  inhibition.   Darwin
relates the following experience : " I put my face close to  the thick glass-plate in front

     1 In this paragraph Meynert quotes almost verbatim from Darwin's " Expressions of the
Emotions in  Man and Animals."  Vid. Am. cd., pp. 33  and 33.  The translator  has, therefore,
rendered this passage  largely in the words of Darwin.—S. 
Appendix.                             277
of a puff-adder in the Zoological Gardens.  Every idea of danger was  entirely  sec-
ondary ;  but as soon as the animal struck at me, my resolution went for nothing, and I
jumped a yard or two backward with astonishing rapidity." '
    Fury is a painful emotion, which throws, the entire cortex, including its sensa-
tions  of  innervation,  into a condition of hyperaesthesra ;  and this  hyperaesthesia is
characterized by great tension of all the muscles, which are in readiness, as it were, to
perform  aggressive, destructive movements.
    The phenomena  of expression, which  we considered hitherto, depended upon
irradiation or secondary associations  (concepts).   But the thoughts and  impressions
of  the  physiognomist himself  bear the stamp  of secondary (parallel)  associations.
Recognition of an oft-repeated impression is effected with astonishing  ease, and as
surprising is the mass of physiognomical material stored up  in our memories.   My
own eyesight is  very good, and  I can  recognize at a distance  a  person  whom I
never  thoroughly looked at.  I  recognize  him, even  if he be turning  a corner at
the very  moment I spy him, by  the peculiarity of  his gait,  by a movement of  the
shoulders, by the way he carries his head, all of which  peculiarities have uncon-
sciously  been  imprinted upon my  mind.  Physiognomical  associations are based,
therefore, upon innumerable details, which have been registered in  the  brain.   The
special features of a person aid us none  in judging of his conscious actions,  and
yet we cannot help inferring similarity of volitional actions in two persons from simi-
larity  in their cast  of features.  Such  conclusions—secondary  associations—are  the
result  of impressions which we can scarcely define in words,  of innumerable images
deposited in the fore-brain.  The features of the face, the development of permanent
wrinkles, will depend much more upon nutritive changes, upon tension or relaxation of
the skin, upon the loss of its elasticity in old age, than upon fixed  innervations repre-
senting actual forms of expression.  Secondary associations (allied concepts) lead us to
put an entirely erroneous interpretation upon movements of expression, which  are
indeed  so variable that we are frequently unable to distinguish between the beginning*
of crying or laughter.
     Hanns Virchow has succeeded admirably in  suggesting a very fine physiognomical
secondary association in regard to the interest  attaching to the pupil of the eye.   The
pupil, he says, is  the portal through which we look  into the  "innermost recess" of
another  person.   A psychical secondary association is connected with the term " inner-
most  recess."   We are reminded of the sensation of an " unfathomable depth, "which a
child experiences on  looking through the door of a cellar or down into a well.  There
can be no doubt, therefore,  that our interpretation  of expressions is simply a matter of
secondary associations.  Physiognomists—and  all persons  are  such—are apt  to be
deceived as to what they really see.  A  person's voice and  external appearance may
remind us so vividly of another's that, at first sight, we recognize that she must be the
sister of the second person.   Placed side by side, these two sisters may present entirely
different features ; the resemblance will lie altogether in certain movements of expres-
sion,  including those of speech, which one has copied from the other.   But the physi-
ognomist referred the resemblance to a similarity of features.   I  have referred to  the
condition of the observer—the physiognomist—in order  to prove  that his judgment is
as largely dependent upon the secondary associations of  partial psychical sleep as are
the phenomena of expression which he has been  observing.  And to such a conclusion
we can surely not ascribe the value of an unerring judgment.
     There  is another order of secondary concepts,  exerting their influence  in every
phase of consciousness, and dependent upon those sensations of  muscular innervation
which represent one's own features and carnage, as copied by one  individual  from.
1 Darwin, toe. cit., p. 38. 
278
Psychiatry.
another.   This image of the personality is subject in most people to certain uncon-
scious aesthetic concepts, which help the individual  to govern the innervation of his
own features and  movements.   If movements of expression  indicate,  to the extent
mentioned above,  all  possible  relations  to the outer world,  or the lack  of such
relations,  then the features and  carriage of a person may be  said to define his own
personality independently of all external considerations.   These  aesthetic considera-
tions modify personal  appearance according to  the  power of the fore-brain over all
innervation, in proportion to the influence of imitation, of taste or  lack of taste, which
are important factors in the matter  of personal  appearance, and  according to the
culture and mental calibre of the individual.
    The control which a person possesses over the most movable body-opening—the
mouth—may be taken as a measure of his mental strength.  Uneducated persons lack
this control  altogether.  The finest  shades of expression, which  cannot be aptly
described in words, are indicated by changes in that depressed region of the face  sur-
rounding  the lips, bounded  above by the  naso-labial and below  by the .genio-labial
fold, which region, according to  Langer, is never disfigured by the accumulation of
adipose tissue.
    By far more universal are  those physiognomical symbols which  the eyes offer
and  which  vary  with slight changes in  pressure, with a change in  the lustre, the
position, and the shadow of the eyes.
    Every one will be  able to distinguish whether certain forms of expression,  as indi-
cated by the features or the carriage of an individual, result from unconscious innerva-
tion with the aid of secondary concepts, or from conscious innervation in a condition
of partial wakefulness.  Volitional mimical movements lack  the character of spon-
taneity, and  become ridiculous  as expressions of  foppishness or  excite  contempt as
expressions of falsehood.  Intentional movements of expression lack that very charm
which is inherent in the unconscious mechanism of expression.
    We shall gain a clearer insight into this subject from the study of the pathological
changes of expression ; and such changes we  shall have  reason to  consider  pathog-
nomonic of certain morbid states of the mind. 
INDEX
                    A
 Acoustic nerve.   (See nerve, auditory.)
 Adamiick;  investigations  on centres
   ocular muscles, 205
 After-brain.  (See medulla oblongata.)
 Aggression.  (See movements.)
 Ala cinerea, 36
 Alveus, 24
 Amphioxus, 1
 Amygdala, 46
 Animals, speech of, 275
 Ansa lenticularis, 50, 81
 Ansa peduncularis, 45, 47, 50
 Ape-fissure, 9
 Apex-process, 65
 Aquaeduct of Sylvius, 30
 Arched fissures of carnivora, 17
 Arndt, 59,  62
 Arnold, 24, 36 ;  fasciculus  of,  85, 137 ;
   lattice-like layer of, 88
 Arteries of brain, 220
 Association-fibres,   39 ;   functional  im-
   portance of, 153
 Association, logical aspect of, 177 ; rela-
   tion to induction, 179
 Associations, secondary,  physiognomical
   importance of, 271, 275
 Auditory bundles,  120,  121  ; communica-
   tions, reflex origin of, 203
 Axis-cylinder, composition  of  sheath,
   233 ;  development  of, 64 ;  fibrillary
   structure of,  243 ;  nutrition  of,  243,
   245
                   B
Baer, Carl v., 1
Base-process, 60
Bat, sensations of, 171
Bechterew,  on voice-centre, 203
Bell, law of conduction,  138 ; on closure
  of the lids, 273
TO  PART  I.
    Bergmann, 36
    Besser, 54, 62
    Betz, 70
    Bindearme.   (See process, cerebell.  ad.
      cerebrum.)
    v.   Bischoff,  13-15 ;  on weight of brain,
      255
    Blankenhorn and Gamgee, on protagon,
      235
    Blushing, 251
    Bochaldek, on vaso-motor nerves, 220
    Boll, 56-67
    Brachia of the corp. quadrigemina, 101
    Brachium-pontis, 28, 115
    Brain,  aqueous extract of, 235 ;  cisterns
      of (see  lymph-cisterns) ;  convex  sur-
      face, 3 ; median  surface,  18 ; minute
      anatomy  of,  56 ;  movements of, 215,
      227 ; nutrition of, 213 ; of  bear, 6 ; of
      hamadryas, 7 ; of monkey, 23 ; of mus-
      tela,  9;  weight of, 255  ; sexual differ-
      ences, 261
    Brain-axis,  dissection of, 25 ; develop-
      ment of, in man, 28
    Brain-trunk, dependent upon fore-brain,
      142.  (See also above.)
    Breuer, on static vertigo, 209
    Briicke, on forced movements, 209
    Burckhardt, on movements of brain, 215,
      217, 229

                      C

   Calcarine fissures,  23
   Canals,  semicircular,  as organs of equilib-
     rium,  263
   Capsula interna, general  anatomy of, 82  ;
     relation to cerebral peduncle, 81
   Cell-process, 58
   Cells, cubic, 61
   Central  gray substance, 35
 |  Centres, subcortical, 156
279 
28o
Psychiatry.
Cerebellar co-ordination, 210
Cerebellum, conduction to and from, 173 ;
  connection with auditory fasciculi, 209 ;
  cortex of,  116; description  of,  115;
  development of, 1-33 ; nucleus dentatus
  of, 118 ; as organ of sensation, 211
Cerebrin, 237
Cervical flexure, 3
Charcot,  arterial  terminology  of,  221 ;
  views on paralysis,  173
Cholesterin, 236
Chorda dorsalis, 3
Choroid plexus, 19
Cingulum, 24, 40
Clarke, 35, 54 ; auditory nucleus of, 118,
  126 ; structure  of  cortex, according to,
  75
Claustrum, formation of, 71
Commissura anterior, 45 ; atrophy of, fol-
  lowing extirpation  of olfactory lobes,
  266 ; medullary formation of, 72 ; rela-
  tion to olfactory lobes, 75
Commissura inferior,  95 ;  media, 94
Commissura,  posterior, bundles to thala-
  mus, 133
Commissure of Wernekinck, 53
Conarium, 31
Convolutions, homology of,  16 ; index of
  intelligence, 260 ; laws of development
  of, 14  ; mechanical  laws governing de-
  velopment of, 262
Convulsion-centre, 212
Cornu ammonis, 3, 24 ; cortical structure
  of, 70
Corona radiata, bundles to optic thalamus,
  76 ;  relations to lenticular nucleus  and
  crus, 78
Corpora  quadrigemina, 31 ;   connections
  with corp. genie, ext. et int., 100, 101  ;
  connections with cortex,  102 ;  periph-
  eral connections of, 103
Corpus, callosum,  3,  20; candicans,  27  ;
  genie,  externum, connections with optic
  tract,  100; restiforme,  28, 36,  126;
  origin  of,   118 ;   relation  to  olivary
  bodies, 128 ; striatum, development of,
  3 (see also nucleus caudatus  and  nucleus
  lenticularis) ; trapezoides, 28
Cortex, cerebellar, 116
Cortex, cerebral, anatomy of,  37,  56, 59 ;
  arterial supply  of,  214 ;  functions  of,
   195 ; of occipital lobe, 68 ;  relation to
   outer world, 139 ; separation of sensory
   and  motor areas,  141 ; as  vaso-motor
   centre, 249
Cortical  inhibition, 197
Cortical localization, proof of, 141
Crus cerebri.  (See pedunculus cerebri.)
Crusta.  (See pes pedunculi.)
Cruveilhier, on venous spaces,  216
Crying, in children, 272
Cuneus,  15 ; thalami optici  intergenicu-
  laris, 102

                   D
Danilewski,  on proportion of  gray and
  white substance in brain, 232
Darwin,  on inheritance of ideas and criti-
  cism of his views, 274
Deiter, 35 ;  lateral mixed system of, 124
Demoulins, on injury to cerebellum, 210
Diakonow, on protagon,  236
Di-encephalon.  (See inter-brain.)
Discus lentiformis,  53, 85
Ditmar,  on  rise  of blood-pressure after
  sensory stimulation,  1S6
Drechsel, views of, on protagon, 236
Duchenne, on movements  of expression,
  276
Dura mater, blood-supply of, 217
Duret, on arterial blood-supply of brain,
  221
Dyspnoea of tissues in relation to move-
  ments  of repulsion, 186
Ecker, convolutions of, 16
Ego, primary and secondary, 175 ; primary
  conception of, 169
Eminentia collateralis  Meckelii, 23
Eminentia teres, 35, 123
Emotion,  influence upon vascular wave,
  253 ; in relation to  aggression and re-
  pulsion, 184 ;  the result of association,
  192
Engel, 36 ; on relation  between thoughts
  and movements, 276
Ep-encephalon.   (See  cerebellum.)
Ependymal formation, 56
Eulenburg and Landois,  experiments of,
  on relation of cortex to changes in tem-
  perature, 189 
Index to  Part I.
281
Expression,   mechanism  of,  271-278  ;
  movements of, in a child, 272
Eye, in expression,  277, 278
Eyelids, mechanism of closure of, 156

                    F

Fascia dentata Tarini,  21, 24
Fasciculi bigemino-geniculares, 101
Fasciculi marginales aquaeducti, 104
Fasciculus, arcuatus, 42 ; basalis internus
   (Burdach),  41
Fasciculus  longitudinalis  posterior, 96,
   133 ;  function  of,  174 ; formation  of,
   205 ;  radiations of,  98
Fasciculus retrofiexus, go, 133
Fasciculus uncinatus, 42
Fear, expression of, 276
Fechner, views on activity of brain, 214 ;
   views on spontaneity of motor actions,
   248
Feeling, divisions of,  193
Ferrier, motor areas of, 143
Fibrae   arcuatae,  different  divisions  of,
   126 ;  relation to auditory tract, 120
Fibrae propriae, 39
Fimbria, 18
Fissura calcarina.  (See sulcus calc.)
Fissura, interparietalis, 8 ;  parallelis, 9 ;
   prae-occipitalis, 15
 Fissure of Rolando. (See sulcus centralis.)
 Fissure of Sylvius,  4
Flechsig, 55, 64 ; investigations of, on de-
   velopment of medullary substance, 268-
   270
 Fleischl, 58
Flocculus, 29
 Flourens on  forced movements, 209
 Foramen of Monro, 3
 Fore-brain,  anatomy of, 3 ; development
   of,  1 ; ganglia of,  25, 75 ;  physiology
   of,  139,  etc.;  as seat  of intelligence,
   149
 Forel,  53
 Fornix, 3, 18, 21, 8g
 Fossa,  ccerulea,  35
 Fossa of Sylvius, 2
 Foveae glandulares, 216
 Foville on cerebellar lesions, 211
 Freedom, phenomena of, 196
 Frenulum, 102
 Frontal flexure,  3
Frontal fissures, etc., 9
Frontal lobe, 9, 10
Funiculus, cuneatus,  36,  127;  gracilis,
  36, 127 ;  lateralis,  28,  125 ; posterior
  of medulla,  127
Fury, 277

                   G
Geniculate bodies, 32
Geoghegan, on nuclein, 233
Gerlach, 63, 65
Girdle-formations of ganglia, 95
Globus pallidus,  80
Glomerulus olfactorius, 70
Goll, column of,  37
Goltz,  croak  experiment of,  188 ;  on
  localization of functions, 149 ; on spinal
  vaso-motor  centres, 185 ; on static ver-
  tigo,  209 ; on voice centres, 203
Granules, 60
Gratiolet, divisions of corp. striatum ac-
  cording to,  76 ; fasciculus  of, 137 ; on
  movements  of expression, 276
Gray substance,  of  cortex, 56, 58 ;  spe-
  cific gravity of, 232
Grief, emotion of, 276
v. Gudden, 27 ; experiments of, 266
Gyrus  fornicatus, 3, 20; in  relation  to
  sense of smell,   141 ;  fusiformis, 15;
  longitudinalis, 10 ; orbitalis, 10 ; transi-
  torius,  10;  uncinatus,  22 ;  cortical
  structure of, last, 70

                    H
 Habenula, 31
 Helmholtz, on space-image, 179
 Henle, 14, 39, 59, 62 ; mechanics of brain
  development, 262
 Hensen and  VSlckers,  investigations  on
  centres for ocular muscles,  205
 Hering, on peristaltic movements of arte-
   ries,  224
 Heubner, on  blood-supply of brain, 217,
   221
 Hind-brain.  (See cerebellum.)
 Hitzig, 18 ; motor centres of, 70, 143
 Hollander, 94
 Hoppe-Seyler, on chemical composition of
   brain, 235, etc.
 Huschke,  12, 22 ;  on cerebellar co-ordi-
   nation, 210 
2S2
Psychiatry.
Hyperaemia, functional, of brain ; changes
  of,  215 ;  how  guarded against,  247 ;
  relation to  emotion, 274 ;  relation to
  thought, 194, 214
Individuality, discussion on,  168
Induction, mechanism of, in brain,  153
Infundibulum, 20, 27
Inhibition, 185
Inspiration, physiognomic value of, 272
Instinct, 169
Intelligence, seat of, 149 ;  mechanism of,
  151
Inter-brain (see also optic thalamus) ; de-
  velopment of, 2, 3 ;  ganglia of, 25
Irradiation, 185 ;  in movements of ex-
  pression, 275
Island of Reil, 2,4; development of, in
  man, and relation  to speech, 142
Isolation, 64

                   J
Jaksch, on nuclein, 233
Jastrowitz, 58, 59, 63,  64, 67

                   K
Keratoid substance,  241
Key, on lymph-cisterns, 215
Kissing, physiognomical aspect of, 274
Koschewinkow, 65
Kossel, on chemical composition of brain,
  235, etc.
Kussmaul, on perceptions in utero, 168
Kuhne and Ewald, digestion, experiments
  on the axis-cylinder, 233

                   L
Lamina  perforata  anterior, relation to
  corp. striat., 77
Laminae medullares, 80 ; connections with
  internal capsule, 83
Landois  and  Wolff,  on pulse-waves of
  brain, 225
Langer, on venous spaces, 216
Language, symbols of, equivalent to cor-
  tical images, 192
Lateral column.  (See funiculus lateralis.)
Lateral mixed system (Deiter's),  124
Laughter,  273
Lecithin, 237
Lemniscus, 34,  52 ; origin of, 103 , con-
  nections of, 134, 135 ;  relation to opt.
  thai, and spinal cord, 202
Lenhossek, 124
Leyden, views on ataxia,  144
Leveille,  34
Lids, closure of  (see also  eyelids);  physi-
  ognomic aspect of, 273
Liebreich, on protagon, 236
Lingula,  33
Lobus candicis, 32 ; occipitalis, 14 ;  parie-
  talis superior, 12 ;  inferior, 13 ;  quad-
  ratus, 13
Localization.  (See cortical localization.)
Loewe, 58
Longet, experiments of, on dogs, 151
Lotze, on psychical spinal cord functions,.
  200; views on local signs,  180 ;  views
  on  muscular  sense,  145 ; on repulsive
  movements, 152 ;  on tactile sensation,
  178
Lusanna,  on cerebellar lesion,  211
Luys, 70
Lymph-cisterns within the skull, 214
Lymph-spaces, subdural, 217

                   M
Mach, on static vertigo, 201
Magendie, on injury to cerebellum, 210
Malacarne, 34
Medipedunculus (Wilder).   (See hrach-
  ium-pontis.)
Medulla  oblongata, development  of,  1  ;
  centres  in, 211 ;  transition  into  spinal
  cord, 128 ; as  vaso-motor centre,  206
Medullary sheaths, 64, 269
Membrane of Schwann, 60
Memory, seat of, 149
Mendel, phosphorus in urine,  242
Mes-encephalon.  (See mid-brain.)
Met-encephalon.  (See after-brain.)
Meyer, Ludwig, on cavernous  spaces, 216^
  on mechanism of brain development,262
Meyer  &  Cornwinder,  phosphorus  in
  plants,  233
Meynert,  base-processes of, 65 ; fasciculus
  of, 90
Mid-brain,  development  of,  1 ; ganglia
  of, 25,  29
Middle cerebellar peduncle.   (See bracfu
  ium-pontis.) 
Index to  Part I.
283
Mischer,  on  spinal-cord connections  of
  lemniscus, 202
Monoplegias, depending upon lesions  of
  lenticular nucleus,  198
Mons, 33
Moods in relation to  movements,  193
Motor areas, criticism of, 143 (see also
  cortical localization);  distribution over
  cortex, 147 ; sensory character of, 145
Movements, aggressive, 176, 185 ; forced,
  209 ; influence of,  upon reflex  actions,
  201 ; inhibition of, 188 (see also  under
  expression) ;  primary  and  secondary,
  156,  159 ;  repulsive,  176, 185 ;  spon-
  taneous, 155
Munk's views on localization, 145

                   N
Nerve, as a conductor, 240
Nerve or nerves:
  I.  (See olfactory bulb.)
  II. (See optic tract, etc.)
  III. (oculo-motor), nucleus of,  107
  IV. (trochlearis), origin of, 108
  V. (trigeminal) descending root of, 107 ;
     description of all roots,  110
  VI. and VII., common  nucleus of, 111
  VII. (facial), anterior nucleus  of, 112 ;
     knee of, no
  VIII. (auditory),  anterior nucleus  of
     Stilling, 122 ;  external nucleus  of,
     120;  relatio* to cerebellum,  115;
     relation to reflex impulses, 274
   IX., X., XL, XII., nuclei of,  125, etc.
Nerve-cells, chemical composition of, 232;
   respiration of, 184
Nerve-current, electrical, 242
Nerve of Lancisi, 21
Nerves of pia, etc., 220
Nothnagel,  chromic-acid  injections into
   lenticular  nucleus,   161  ;  convulsion
   centre of, 212 ;  nodus cursorius of, 197 ;
   on motor areas,  143
Nuclein, 233, 245
Neuroglia,  56
Neurokeratin, 239
Nucleus caudatus, 2, 26, 76 ;  proportion-
   ate development  of,  in man and ani-
   mals,  78
Nucleus, caudatus thalami,  89
Nucleus dentatus (of cerebellum), 53
Nucleus lenticularis, 2 ; description of, 79
Nucleus (tegmenti) ruber, 53 ; relations to
   internal capsule, 85
Nutrition, phases of, in cortex,  193
Nutritive attraction, principle of, applied,
   247

                   0
Obersteiner, views of, on cerebellar cor-
   tex, 116
Obex, 36
Occipital lobe, convolutions of, 16; fissures
   of, 16
Ocular, movements, reflex mechanism of,
   204;  muscles, centres of,  205.  (See
   also under Eye.)
Olfactory bulb, 16
Olfactory lobe, 6, 18
Olivary bodies, 28, 127 ;  relation to corp.
   restiforme,  128
Operculum, 5
Optic radiations, 48
Optic thalamus, description of, 86 ;  con-
   nection (?) with auditory tract, 203 ; re-
   lation to  upper extremity, 161 ; relation
   to various senses, 199 ; symptoms  from
   lesion of, 165  ; parts of, 31, 47,  133
Optic tract, 95 ; connections with corp.
   genie,  ext., 100 ; radiations from,  101
Orbital surface, convolutions of, 12
Owsjannikow, on oblongata, 206 ;  on rise
   of blood-pressure after sensory stimula-
   tion, 186

                    P
r
 Pacchionian granulations, in relation to
   subarachnoidal spaces, 219
 Pain, in  relation  to movements of repul-
   sion, 191
 Pansch,  14
 Parietal arches, 13
 Parietal flexure,  3
 Parietal lobe, 12  ; fissures of, 12
 Pedicles, of thalamus, 84, 89
 Pedunculus (crus) cerebri, 27,  etc.
 Pedunculus ganglii habenulae, 90
 Pes pedunculi (crusta), 28 ;  double origin
   of, 84, 137
 Petrowski,  analysis by, of gray and white
   substance 238 ; on percentage of water
   in brain, 235 
284
Psychiatry.
Pfleger, on brain-weights, 255, 259
Phosphoric acid, amount of, in body, 235
Phosphorus, in brain tissue, 234 ; in fcetal
  muscles, 234 ; in urine, 242
Praepedunculus  (Wilder).  (See  processus
  cerebell. ad cerebrum.)
Proc. cerebell. ad  cerebrum, 34, 53, 106
Proc.  cerebell. ad  corp. quadrig.,  34.
  (See frenulum.)
Processus cerebell. ad med. oblong.  (See
  corpus restiforme.)
Process,  cerebell.  ad   pontem.   (See
  brachium-pontis.)
Projection, relation to induction, 179
Projection-fibres, 39,  46 ;  from occipital
  lobe, 86
Projection-system, divisions of,  79 ; func-
  tional importance of, 153
Prosencephalon.   (See fore-brain.)
Protagon, 236, 237
Psychical blindness, 145. (See also Munk's
  views.)
Psychical deafness, 145
Purkinje, cells of, 117
Pulse-waves of brain,  225
Pulvinar, 31
Pyramidal tract, 50
Pyramids, 28 ; decussation of,  131

                   Q
Quinke's cinnabar injections, 229

                   R

Rage, expression of,  276
Ranvier's internodia, 60
Red nucleus.  (See nucleus ruber.)
Reinisch, 62
Renzi, on cerebellar lesions, 211
Repulsion.  (See under movements.)
Restiform body.  (See corpus restiforme.)
Retina, images of, how utilized, 180
Retzius, on lymph-cisterns, 215
Riegel, on  peristaltic movements of ar-
   teries,  224
Rindfleisch, 59, 63
 Ritter's laws of nerve nutrition, 240
 Rohony, on amphioxus lanceolatus, 1
 Rokitansky,  56
 Rokitansky,  Procop,  on  respiratory cen-
   tres, 186
Rudinger,  on  development  of convolu-
  tions, 261
Rumpf,  experiments  on  axis - cylinder
  sheath, 233

                   S

Sander, 15
Schiff, experiments with colocynth, 151 ;
  on cutaneous irritation, 184
Schlesinger, on vaso-motor centres, 185
Schmidt, 22
Schnopfhagen's decussation, 95
Schroder,  35
Schultze, Max, 62, 64 ;  on axis-cylinder,
  243
Schwalbe on lymph cisterns, 215
Schwann,  sheath of,  60
Screaming in children, 272
Sensations, correlated,  178 ; of innerva-
  tion, 144, 159, 182 ; in the blind, 171
Sense  or senses, muscular in  relation to
  cerebellum, 210 ;  special,  development
  of, 171 ; tactile, in relation to space, 178
Sensitiveness, of brain cells, 138
Sensory stimuli, in  relation  to  arterial
  changes, 190 ;  nutrition  of  nervous
  tissues,  269
Septum pellucidum, 20
Sighing, 273
Skull, measurements of, 263 ;  relation to
  convolutions, 262
Soemmering,  substance of, 51
Soltmann, on motor functions in children,
   166
Sound, reproduction of, 208
Space-image, retinal, 179, 182
Space, perception of, 178
Space-vision, 181 ; in children, 274
Spiess, views on muscular sense,  145 ; on
   local signs of correlated sensations, 178
Spinal cord, cross-section of, 131
Stannius,  27
Stilling, 33, 35 ;  anterior acoustic nucleus,
   of,  122
 Stilling's wreaths, 51
Stilus of thalamus, 88, 93
 Stratum intermedium caudicis, 55
 Stratum intermed. pedunculi, 51, 54, 82,
   136, 174
 Stratum  zonale,  of  medulla,  126,  127 ;
   of thalamus, 86 
Index to Part I.
285
Stria cornea, 29
Striae medullares, of thalamus, 91
Substantia,  ferruginosa, 109 ; connection
  with root of fifth nerve, no ; innom-
  inata, Reil, 94 ;  nigra, 51 ; of Rolando,
  130
Sucking, physiognomic aspect of,  272
Sulcus calcarinus,  23 ;  structure of, 69
Sulcus, centralis (Rolando), 7 ; of bear, 17
Sulcus cruciatus, 11 ; magnus horizontalis,
  29 ;  praecentralis, 8 ;  rectus,  n
Sylvian fossa, development of,  2
Tapetum Reilii, 44
Tegmentum, 55 ; origin of, 90 ; continua-
  tion of, in spinal cord, 133
Temporal lobe, fissures and convolutions
  of,  16
Thalam-encephalon.   (See inter-brain.)
Thalamus.  (See optic thalamus.)
Thought, methods of, 177 ; orderly evolu-
  tion of, 253
Tractus transversus pedunculi, 27
Trapezoid   bodies.   (See  corpus trape-
  zoides.)
Trigonum, cervicale (Goll), \i%
Trigonum olfactorium, 20, 21
Trollard, 216
Tuberculum cinereum, (Rolando) 37
Tuczek,  on increase of brain-weight, 256
Tiirck, 55 ; bundles of, 85
'Tween-brain.   (See inter-brain.)
U
Uvula, 29
Vagus (X) see nerves.
Vascular waves, of brain-movements, 228 ;
  during sleep and waking, 231
Vaso-dilators, 207
Vaso-motor centres,  in  cortex, 249 ;  in
  medulla oblongata, 206 ;  in spinal cord,
  185
Veins of brain, 220
Velum medullare superius,  33
Vesicles of  hemispheres,'  of  fore-brain,
  etc.,  1, 2
Vieussens,  47
Virchow,  56
Virchow,  Hanns, on  expression  of  the
   eye, 277
Visual sphere, of Munck, 146
Volckers.  (See Hensen.)

                   W

Wagner, Rudolf, on  complexity of con-
  volutions as  an index to intelligence,
  261
Water, percentage of, in brain, 235,  239
Weichselbaum, on brain-weights, 255
Weight, proportional, of brain, 257, etc.
Welcker,  on influence of  female skull
  upon convolutions,  262
Wernekinck, 53
Wernicke,  15
White substance, specific gravity of, 232
Wilder, 17, 53
World, conception of, 183
Wundt, 14 ; views  on induction, 153 ;
  on space-image,  179 ;   on  speech  in
  animals, 275
Zuckerkandl, investigations on  develop-
  ment of convolutions, 265 
 
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