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Comparative Neurology |
A OUARTERLY PERIODICAL DEVOTED TO THE
Comparative Study of the Nervous System.
EDITED BY
C. lL. Herrick, Socorro, NEw MExIco.
aSSOCIATED WITH
OLIVER S. SyRONG, COLUMBIA UNIVERSITY,
C. JupDsoN HERRICK, DENISON UNIVERSITY.
AND WITH THE COUtLABORATION OF
LEWELLYs F. BARKER, M.B., University of Chicago and Rush Medical College
Dr. FRANK J. COLE, University of Liverpool; HENRY H. DONALDsON, Ph.D.,
University of Chicago; PROFESSOR LUDWIG EDINGER, Frankfurt a-M.;
PROFESSOR A. VAN GEHUCHTEN, Untversitté de Louvain; C F. Hopce, Ph.D.,
Clark University; G CARL HuBER, M.D., University of Michigan ; B. F.
KINGSBURY, Ph.D., Cornell University and the New York State Vetert-
nary College; FREDERIC S. LEE, Ph.D., Columbia University; ADOLF
MEYER, M.D., Pathological Instetute, New York; A. D.
MorrILL, M.S., AHamzlton College; G. H. PARKER, S.D.,
Harvard University.
VOLUME XIII, 1903.
DENISON UNIVERSITY, GRANVILLE, OHIO, U.S. A.
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THE
JournaL oF Comparative NeEuro.oey.
ContTENTS oF VOLUME XIII, 1903.
No. J, APRIL, 1903.
Pages 1—52. i—xx. Plates I—II.
CONTRIBUTED ARTICLES.
The Fore-Brain of Macacus. By Wm. WoLFE LEsEM, M. A. ( Columédzta
Cuivezsity.\ an Wwithprlatesmy andi aes ssa ne eee eee ee
Brain- Weights of Animals with Special Reference to the Weight of the
Brain in the Macaque Monkey. By EDWARD ANTHONY SPITZKA,
M.D. (From the Anatomical Laboratory, Columbia University.)
A Description of Charts Showing the Areas of the Cross-Sections of the
Human Spinal Cord at the Level of Each Spinal Nerve, By
Henry H. DonALpson and DaAvip J. Davis. (rom the Neuro-
logical Laboratory of the University of Chicago.) With Chart I__--
The Brain of the Archzoceti. By G. ELtior SmMirH, M. A., M. D.,
Fellow of St. Johns College, Cambridge; Professor of Anatomy, Egy-
tian School of Medicine, Cairo. With four figures in the text_____
LITERARY NOTICES
Functional Changes in the Dendrites of Cortical Neurones-._.-..
The Morphological Position of the Chorda Tympani in Reptiles__
Mendel and Jacobsohn’s Jahresbericht: Fifth Issue_....--_____-
Nervoustoystenion Myxines- i. oe eb eee oe
Waste and the Fifth Nerve 2—-=222—--<- ee eS SR Co eee
be) Phyloceny of the Palliam, 22/2000 2 ooo ceo ee
Obsessions and Psychasthenia
MeMunrichy sem bryOlo gy) aaa 2 ee Se ere yee ye
MotomNerveslenminiiiniimsectSeas=--s-s2eo ae oeee ere n eae
The Comparative Anatomy of the Brains of Lemurs and Other
Mammals
9
41
No. 2, JUNE, 1903.
Pages 53—156, xxi—xxviii. Plates II—IV.
CONTRIBUTED ARTICLES.
An Enumeration of the Medullated Nerve Fibers in the Dorsal Roots of
the Spinal Nerves of Man. By CHARLES INGBERT. (From the
Neurological Laboratory of the University of Chicago.) With thirty-
GOMNCUTESS 22 ae oe ES SL oe Bo a) Se ee 53
On the Phylogeny and Morphological Position of the Terminal Buds of
Fishes. By C. Jupson Herrick. (Studies from the Neurological
Laboratory of Dentson Universtty, No. XViD) eee aoa 121
On the Nature of the Pericellular Network of Nerve Cells. By SHINKISHI
Hatat. (From the Neurological Laboratory of the University of
Chicago.) With ‘Plate TIl..- -2.2).- 2-2 eee 139
The Neurokeratin in the Medullary Sheaths of the Beveneral Nerves of
Mammals. By SHINKISHI HaTal. (from the Neurological Labor-
atory of the University of Chicago.) With Plate IV_.----. ee 149
LITERARY NOTICES.
Hearing and Allied Senses in) Pishes) 22222562 eae eee XX1
Taste Fibers and their Independence of the Trigeminus_-___ -_-- XXiil
DevKursac’s Psychiatry-2.--.85=. Skee eee ee ee XXIV
hesEvolution of Man and his Mind) 2222) --5-— === =e XXV
The Brain and Nerves of the Anamnia+-2-222222> 5222252 XXV
he Dorsal Spino-cerebellar Dract=-= =) == ee XXxvi
The Optic Chiasma in Symmetrical and Asymmetrical Teleosts-_ xxvi
Brain, Weights of Eminent Men: <2-22222 25. 22s cs eens eee xxvii
dhe Lateral Sensory System’ of whe Belsi222=222 2-2 oa eee XXvili
No, 3, OCTOBER, 1903.
Pages 157—258. Plates V—VII.
CONTRIBUTED ARTICLES.
The Neurofibrillar Structures in the Ganglia of the Leech and Crayfish
with Especial Reference to the Neurone Theory. By C. W. PREN-
Tiss. Parker Fellow in Zoilogy, Harvard University. With Plates
Wrand: Wiles.) cect cos ae et eee ee eee ee 157
On the Increase in the Number of Medullated Maree Fibers in the Ven-
tral Roots of the Spinal Nerves of the Growing White Rat. By
SHINKISHI Hatal. (from the Neurological Laboratory of the Uni-
DERSELIV OP A CHICOL OL) 3 ax Oe ta See ene eee ne en 77
On the Medullated Nerve Fibers Crossing the Site of Lesions in the
Brain of the White Rat. By S. WALTER RANSON. Jnstructor in
Anatomy, Marion-Sims-Beaumont Medical School, St. Louis Univer=
sity. (From the Neurological Laboratory of the University of Chicago.)
NVainhp la tem Vallis sees Soka ieee eee oe ae ee eS 185
On the Density of the Cutaneous Innervation in Man. By CHARLEs E.
INGBERT. (From the Neurological Laboratory of the University of
CHICAS GS a eee nee ae oe Se ee a pe a hs Vat is Sa 209
On a Law Determining the Number of Meguilared Nerve Fibers inner
vating the Thigh, Shank and Foot of the Frog—Rana virescens.
By Henry H. DonALpson. (from the Neurological Laboratory of
CREM RICET SIV OFS ORICA POs) eae nye ee einem eee See 223
No. 4, DECEMBER, 1903.
Pages 259—335, xxix—xliv.
CONTRIBUTED ARTICLES.
The Rate of the Nervous Impulse in the Ventral Nerve-Cord of Certain
Worms. By O, P. JENKINS and A. J. CARLSON. (From the Hopkins’
Seaside Laboratory and the Physiological Laboratory of Leland Stan-
ord a) tC river sii.) With tourteensucunest os] s— ee see so ace ee 259
Notes on the Technique of Weigert’s Method tor Staining Medullated
Nerve Fibers. By OLIVER 5S. STRONG, Columbia University, New
Vor eed ere ee Nae me ene a ae ates ek oes aa Se 291
The Doctrine of Nerve Components and Some of Its Applications.
Byee.7 \UDSONW EER RICK? Sooo 22 oe eee, Oe eee 301
Colnmella Auris and Nervus Facialis in the Urodela. By B. F.
[SID VEIS Eta eM tM ee ENGL ENROL EA NOT Be RENCE NINE ABCD 313
BditonaleAnnouncement sins. 22s. 2 See Sows sos oe eee ee 335
LITERARY NOTICES.
ihe Relations of) Biology and! Psychology =—2—- —2= - 2 Seer XX1X
ANG: TESS ACLNONO TE COVE VeNC LNCS) ON ae Oe Sa Oe oore XxXxXill
he svore-brain ofthe yBird2 0.220) Aes ee See ee ee AXE XIE
The Optic Chiasma and the Post-optic Commissure.__.---------- xlii
Peripheral Nerve Endings in Amphioxus________._------------ xlill
On the Lobus Impar of the Brain of Cyprinoid Fishes.___-____- xliv
VotumMeE XIII. 1903. NUMBER I
THE
JournaL or Comparative Neurovocy.
4
THE FORE-BRAIN OF MACACUS.
By Wm. Wo tre Lesem, M. A.
With Plates I and II.
The present article is the result of investigations upon the
simian brain pursued by the writer during the winter of Ig00
in the anatomical laboratory of Columbia University. A
careful search of the bibliography of the simian brain failed to
show any article dealing with the species in question. Here
and there the writer came across rather poor drawings of the
macaque brain but nowhere did he meet with any description
thereof except in Flatau and Jacobsohn’s Comparative Anat-
omy of the Central Nervous System of Mammals. In the
Anatomical Museum of Columbia University the writer has
had access to a sufficiently large number of macaque brains to
render his observations fairly accurate.
Compared with the dog, Macacus presents many striking
advances. A higher type of gyri and sulci, a well developed
occipital lobe with a posterior cornu, a calcar avis, a prominent
forceps major, and an enormously developed temporo-sphenoti-
dal lobe are some of the points which will be discussed in the
ensuing pages.
Whereas in the dog the ventral aspect of the encephalic
segments lies almost entirely in the same plane, the brain of
Macacus presents that convexity of the pons Varolii so marked
in man. The pons of Macacus differs moreover from that of
the carnivores in being actually larger than the medulla. In
the carnivores the crura cerebri are plainly visible upon the base
of the brain as two large bundles of fibres which extend from
the pons and diverge to enter the cerebral hemispheres opposite
’
2 JoURNAL OF COMPARATIVE NEUROLOGY.
the optic chiasma. The crura of Macacus are not visible on
the base of the brain. They are entirely hidden from view by
the well-developed temporo-sphenoidal and the occipital lobes.
In contradistinction to dog and man Macacus presents but a
single corpus albicans, which occupies a mesial position. We
naturally expect to find a well-developed olfactory apparatus in
dogs; and such is the case, for the olfactory bulb projects be-
yond the hemispheres. The olfactory lobes, the bulbs and the
olfactory tracts of Macacus are greatly atrophied. Compared
with the dog the orbital surface of the frontal lobe has likewise
retrograded.
The Hemispheres.
The growth backward of the body of the lateral ventricle
in Macacus results in the formation of a posterior cornu, and
gives us an additional lobe, the occipital. The occipital lobe is
merely a differentiation of the posterior part of the parietal lobe.
In Macacus it is very extensive, comprising about a third of
the entire hemisphere. In man the occipital lobe comprises
less than a sixth of the secondary fore-brain.
The hemispheres of Macacus are in contact with one
another throughout their entire extent; even the apical portion
of the frontal lobes are contiguous. In the dog the frontal
apices are slightly separated, and the rounded posterior extrem-
ities of the parietal lobes diverge considerably to permit of the
reception of the worm of the cerebellum between them. The
entire hemisphere of Macacus is slightly curved from before
backwards. This is most marked in the frontal lobe, where
the apex curves sharply downwards in a hook-like manner.
This curve is due to the non-development of the orbital sur-
face. Externally the frontal lobes are flattened. The parietal
and the occipital lobes are curved only slightly.
The arrangement of the fissures and the convolutions of
Macacus closely resembles the condition met with in the human
foetus. The numerous annectent gyri of the adult human
brain renders it difficult to homologize the gyri of the adult
brain with those of Macacus. The Sylvian, the Rolandic, the
LresEM, Fore-Brain of Macacus. 3
inferior occipital, the par-occipital, the calloso-marginal, and
the calcarine fissures divide the hemispheres of Macacus into
frontal, parietal, occipital, and limbic lobes. A brief descrip-
tion of these fissures is therefore desirable at this juncture.
The Sylvian fissure is oblique in direction. In man it is
horizontal, in carnivores almost vertical. It starts at the base
of the brain, separating the orbital surface of the frontal from
the temporal lobe. At first it proceeds laterally, then ob-
liquely upwards and backwards, and finally terminates by join-
ing the parallel fissure. In one specimen of Macacus nemes-
trinus under observation, the Sylvian fissure did not join the
temporo-sphenoidal. Owing to the non-development of the
orbital surface of the frontal lobe, the sylvian fissure in Macacus
rhesus has no anterior limb. In Macacus nemestrinus, how-
ever, there exists a small rudimentary fissure occupying the
position of the anterior Sylvian limb, but not continuous with
the Sylvian sulcus.
The fissure of Rolando is very similar in its course to that
of man. It runs from just below the great longitudinal fissure
and curves sharply forwards and downwards. Before its termi-
nation, just above the mesial portion of the Sylvian fissure, the
fissure of Rolando curves slightly backwards.
The par-occipital fissure runs sinuously from the great
longitudinal fissure almost to the inferior margin of the hemis-
phere. Externally it is hidden from view by the growth for-
ward of the occipital lobe. This growth forward of the occi-
pital lobe results in the formation of a fissure, the ‘‘Affen-
spalte.’’ This fissure, called by some the external occipital
sulcus, is peculiar to Quadrumana. Upon drawing aside the
‘“‘Affenspalte” we find lying in its floor two annectent gyri
belonging to the par-occipital fissure. The par-occipital fissure
is joined by the parallel and the intraparietal sulci.
The inferior occipital fissure extends from the posterior
margin of the occipital lobe almost to the parallel fissure. It
is curved forwards and upwards, and passes just below the
‘‘Affenspalte.”’
The calcarine fissure lies upon the mesial aspect of the
4 JOURNAL OF COMPARATIVE NEUROLOGY.
occipital lobe. It separates the temporal lobe from the occi-
pital. At its origin it consists of two parts, an upper limb
which arises from the superior margin of the occipital lobe and
a shorter, lower limb which commences a little below the centre
of the occipital lobe. These two limbs unite midway between
the upper and the lower margins of the cerebrum. The calca-
rine fissure then runs at first downwards and forwards to the
base of the hemisphere. It then passes forwards and slightly
upwards, and terminates in the dentate fissure.
The calloso-marginal sulcus extends from the middle of the
great longitudinal fissure almost to the apex of the frontal lobe.
At first it curves downwards, then courses directly forwards,
and finally curves upwards to terminate in the great longitudinal
fissure. Before curving upwards it gives off a short inferior
limb.
The Frontal Lobe.
The frontal lobe presents three surfaces, external, internal
and orbital. The external surface is bounded inferiorly by the
Sylvian fissure and posteriorly by Rolando. The external
surface presents two fissures, the precentral and the horizontal.
The precentral fissure is vertical in direction, and lies midway
between the apex of the lobe and the fissure of Rolando.
Superiorly it terminates by dividing into an anterior and a
posterior limb.
The horizontal fissure lies a little posterior to the apex of
the frontal lobe. It runs at right angles to the precentral sul-
cus. Posteriorly it curves slightly upwards.
The precentral and the horizontal fissures divide the
frontal lobe into three convolutions. Of these the most pos-
terior one corresponds exactly to the ascending frontal gyrus of
man being bounded anteriorly by the precentral sulcus, inferi-
orly by Sylvius and posteriorly by Rolando. Just what the
remaining two gyri are is difficult to say. BiscHorF declares
that in the gorilla and the orang Broca’s convolution is but ill-
developed ; and according to Panscu the third frontal convolu-
tion is absent in all other apes. If Panscu be correct in his
Lrsem, Fore-Brain of Macacus. 5
theory we may homologize the upper frontal gyrus of Macacus
with the first frontal of man, and the remaining lower gyrus
with the second frontal.
The mesial aspect of the frontal lobe presents the marginal
gyrus enclosed by the calloso-marginal fissure. The gyrus
fornicatus is continuous with that portion of the frontal lobe
which in man is known as the precuneus.
We have already noted the concave non-developed orbital
surface of the frontal lobe.
The Parietal Lobe.
The parietal lobe has two surfaces; an external one
bounded anteriorly by Rolando, inferiorly by Sylvius, and pos-
teriorly by the ‘‘Affenspalte,’’ and a mesial surface which is
continuous with the gyrus fornicatus. The external surface
presents the intra-parietal fissure. This sulcus lies between the
fissure of Rolando and the external occipital sulcus. ~It starts
a little posterior to the fissure of Rolando, and passes upwards
and backwards. Then it curves upon itself, and terminates in
the par-occipital sulcus. The intra-parietal fissure was origi-
nally composed of three distinct fissures, a superior, an inferior,
and a horizontal parietal sulcus. This condition is still evident
in the adult human brain where the three parts of the intra-
parietal sulcus are separated from one another by numerous
annectent gyri.
The external surface of the parietal lobe presents two gyri,
a superior and an inferior parietal gyrus. The superior parietal
gyrus represents the ascending parietal and the superior parietal
convolutions of man. The inferior parietal gyrus may be
divided into supramarginal and angular convolutions. The
supramarginal is bounded anteriorly by the intra-parietal sulcus,
posteriorly by the parallel fissure, and inferiorly by the fissure
of Sylvius. The angular is bounded in front by the temporo-
sphenoidal sulcus, below by the inferior occipital, and behind
by the external occipital.
6 JOURNAL OF COMPARATIVE NEUROLOGY.
Temporo-Sphenotdal Lobe.
This lobe is very highly developed in Macacus. Its ex-
ternal surface presents the parallel fissure which is the most
extensive sulcus of the cerebrum. It starts near the apex of
the temporal lobe, and extends almost to the great longitudinal
fissure; and there it joins the parieto-occipital fissure. Inferi-
orly it curves slightly forward; while superiorly it curves
slightly backwards. The parallel fissure divides the temporal
lobe into an upper and a lower gyrus. The lower gyrus is
continued on to the base of the lobe. The superior convolu-
tion lies below the supramarginal gyrus. It is bounded anteri-
orly and above by the Sylvian fissure, and posteriorly and be-
low by the parallel fissure. The base of the temporo-sphen-
oidal lobe is divided into two convolutions by the collateral
fissure. This sulcus runs almost parallel with the inferior mar-
gin of the temporal lobe. It extends from within a short dis-
tance of the posterior temporal pole almost to the apex of the
lobe. The collateral fissure forms the lower boundary of the
hippocampal gyrus.
The Occtpital Lobe.
As in man, the occipital lobe of Macacus presents an
external, an internal and a basal surface. Externally with the
exception of the superior occipital sulcus the occipital lobe is
entirely smooth. The superior occipital fissure runs at right
angles to the external occipital fissure. Externally the occi-
pital lobe is separated from: the parietal by the par-occipital
fissure. The inferior occipital fissure separates the occipital
from the temporal lobe. The mesial surface of the occipital
lobe presents the cuneus, bounded in front by the parieto- ©
occipital fissure and behind by the calcarine.
The Limbic Lobe.
The limbic lobe is bounded above by the calloso-marginal.
fissure, posteriorly by the rudimentary post-limbic sulcus,
and inferiorly by the collateral fissure. This lobe includes the
hippocampal and the fornicate gyri. The gyrus fornicatus
Lesem, Fore-Brain of Macacus. 7
extends from the genu of the corpus callosum to the lower
border of the splenium. Here it becomes the hippocampal
gyrus. The latter is limited above by the collateral sulcus. In
Macacus as in man the hippocampal gyrus forms a convolution
of the temporal lobe, and is fused with the rest of hemisphere.
In the brain of the sheep this is not the case; the hippocampus
has no connection whatsoever with the exterior of the brain.
In Quain’s ‘‘Anatomy of the Human Brain’ BEEvor is quoted
as saying that the hippocampus major of apes receives no
fibres whatsoever from the lyra of the fornix. To determine
this point I carefully dissected two brains of Macacus and
found in both a distinct band of fibres running from the lyra of
the fornix to the hippocampus major,
The island of Reil in Macacus consists of two convolu-
tions derived from the orbital surface of the frontal lobe. As
in man the insula is overlapped by the operculum, and is thus
invisible on the exterior of the undissected brain. In carni-
vores owing to the non-development of a large temporo-
sphenoidal lobe, no insula exists.
The Lateral Ventricles.
The lateral ventricles of Macacus are especially interesting
owing to the enormous extent to which the posterior cornu is
developed. This development is not uniformly attained by
man. Numerous cases are on record where the posterior
cornu has been of small size or rudimentary. In the past year
I have seen two brains, one that of a child two years old, the
other an adult brain of thirty years, in which the posterior
cornu of the left side measured 1.5 cm. and 2 cm. respectively.
The right posterior cornu was well-developed in both cases.
The posterior horn of Macacus presents a well-developed bulb,
but an ill-developed calcar avis. The anterior and the descend-
ing cornua present no features markedly different from those
of man.
The corpus striatum of Macacus is remarkable in that the
lenticular nucleus seems to exceed the caudate in size. As in
man the lenticular nucleus consists of three parts, an outer
8 JOURNAL OF COMPARATIVE NEUROLOGY.
portion known as the putamen, and two inner divisions called
the globus pallidus. In carnivores no such division exists.
The corpus callosum of Macacus is very short. It pre-
sents, however, a well-developed forceps major and a forceps
minor. The nerves of Lancisi are also plainly discernible.
These cannot be differentiated in the dog. The splenium of
the corpus callosum sends off a thick bundle of fibres which
fuses with the hippocampus of both sides and serves as a com-
missure between them.
The anterior commissure is more extensive than in carni-
vores. It runs into the temporal lobe. Its termination can be
ascertained only by microscopic methods.
The Third Ventricle.
The cavity of the third ventricle is extremely small and
narrow. This is due to the fusion across the median line of
the large optic thalami, which are continuous with one another
throughout their length except inferiorly. This fusion across
the median line represents the middle commissure of man.
From this brief macroscopic study of the fore brain of
Macacus we see that the simian brain closely resembles that of
man; for Macacus seems to present most of the conditions
existing in man, the sole difference in most instances being one
of degree.
DESCRIPTION OF PLATES.
PLATE I.
fig. z. The external surface of the left hemisphere of Macacus rhesus.
fig. 2. Mesial surface of left hemisphere of Macacus rhesus.
PLATE II.
fig. 7. Mesial surface of the left hemisphere of Macacus nemestrinus.
fig. 2. External surface of cerebrum of Macacus nemestrinus. Part of
the occipital lobe has been removed to show the annectent gyri.
JOURNAL OF COMPARATIVE NEUROLOGY. VOL. XIII. PEATE.
Rolando
Horizon-
tal fissure Affen-
spalte
Precentral ee
; nferior
Sudineay Occipital
Parallel
Sylvius fissure
Occipital
Calloso-
marginal
Fornix
Frontal
Pons Lobe
JOURNAL OF COMPARATIVE NEUROLOGY. VoL. XIll.
Precuneus
Occipital
Sulcus
Calcarine
fissure
Ascending
Frontal
Inf. trans-
verse
fissure
Second
Frontal
PLATE Il-
Calloso-
marginal
Annectent
gyri
Occipital
Lobe
Temporal
Lobe
My
7 4
A
BRAIN-WEIGHTS OF ANIMALS WITH SPECIAL REF-
ERENCE TO THE WEIGHT OF THE BRAIN IN
THE MACAQUE MONKEY.
By Epwarp ANTHONY SpitTzKa, M. D.,
Alumni Association Fellow in Anatomy, Columbia University.
(From the Anatomical Laboratory, Columbia.)
The accumulation of considerable material for morphologi-
cal study during a period of over ten years has furnished a
series of brain-weights whose publication as a contribution to
. the subject from a comparative standpoint seems desirable.*
All the animals whose brain-weights are here given were
Mammals (204 in number), the great majority belonging to the
Quadrumana, among them being 80 of the genus Macacus. Of
the total number, 192 brains were weighed in the fresh state,
the remaining 12 after the body had been injected with a zinc
chlorid solution. The latter series is tabulated separately.
The weights are expressed in grammes. In all cases the brain
was severed from the spinal cord at the foramen magnum and
weighed with its pialinvestment. In nearly all cases the body-
weight was also recorded, giving the relative as well as the ab-
solute brain-weight. In this connection it must be noted that
many of the animals, particularly among the Quadrumana, were
quite young, giving ratios of body and brain-weight not gener-
ally applicable to the adult animal. Thus, among the gyren-
1 The writer is indebted to Professor GEORGE S. HUNTINGTON for the
privilege of compiling these data.
10 JOURNAL OF COMPARATIVE NEUROLOGY.
cephalic Mammals, we find such ratios as 1:17 for a young
Chimpanzee, and 1:20 for a young Coati-mundi. Of course,
such cases can not be taken as standards any more than they
can in the human species, where the new-born babe, with a
ratio of 1:8 has relatively five times as heavy a brain as an
adult man. Furthermore it must be remembered that in the
accession of such material as is comprised in this collection,
most animals arrive in a poorly-nourished, half-starved condi-
tion, or they have died as the result of wasting diseases; in.
either case losing considerable body-weight and materially de-
tracting from the value of any computations of any brain- and.
body-weight ratios. It is fortunate that the brain attains to:
nearly its largest size so early in life, and that its weight is so
slightly affected by starvation and disease, and it is for this
reason that the writer ventures to subject the large series of
brain-weights of the Macaque monkeys to a special analysis.
However, since the body-weight alone as a criterion or as a
means of comparison is inadequate, it is our purpose hereafter
to record as well the bodily dimensions, such as the length from:
vertex to heel, or to the root of the tail, and particularly mea-
surements of the head.
The list of brain-weights, with the sex, body-weight, and
ratio (the brain-weight is considered as equivalent to 1),
follows :
Spitzka, Brain-Weights of Animals.
TABLE I.
FRESH BRAIN WEIGHTS.
— | SSeS
1|Troglodytes niger, juv.
2 sé “é “es
Semnopithecus entellus,
1,Cercopithecus callitrichus, 3159 64 49
2 «6 66 2898 37 51
3 66 «6 1679 64 26
& % 845 59 T5
66 66 2 140 54 40
Cercopithecus ne-s=ss=—> 1502 62 24
1/Cercopithecus mona, 3001 67 45
2 se 6
Cercopithecus griseo-viridis,
é
2
ef
3
é
2
2
a
é
3
1|Chlorocebus sabaeus, juv. fe) 1036 50 21
2 6 66 66 Rae 1480 71 21
Chlorocebus cynosurus, ay 3880 68.5 57
1|Cercocebus fuliginosus, eS eee es 97) \Sazanceee
2 oe “ce & 1353 gI 15
6e “cc ce) 1398 105 13
1/Macacus rhesus, ay 5190 93 56
2 “ s S 2620 92.5 28
3 v5 rs ae e535 92 17
4 46 “ a 1250 go 14
5 mi a o 1173 87 13-5
6 66 66 a 2072 86 24
7 us Gu a 1928 86 20
8 se es zB 1551 82 19
9 se oe é 1327 81.5 16
10 5 Sy S| 3079 81 38
1! OG se Ag 1350 80 17
12 OY OC & 1672 78.5 21
13 “6 “ec Be 912 78 9 3
14 i a $| 1400 77 18
15 is n é 744 77 9-5
16 oe Ss ze 1275 76 17
17 a6 “sé é 897 75 12
18 a ; $| 1079 75 14
19 ee ie S| 1106 74 15
20 se UG a 1602 74 21.5
ae cs 3} 1353 73 18
22 “se oe & 895 WB 12
23 66 a6 as I 105 73 15
24 ae “6 & eats BS ct 72 Be rea se
25 os oc g 1248 64 19
26 od Oe Q 2025.5 98 21
27 i ay 2 1325 95 14
28 an ne ce) 1207 89 13.5
29 of “ < 1905 92 21
30 ss 6s 9 1900 86 22
“
4
JouRNAL OF COMPARATIVE NEUROLOGY.
Ratio:
Brain- W't
No QUADRUMANA Sex|Body-W’t|Brain-W’t) =I!
Grams. | Grams.
33|Macacus rhesus, Q 1685 81 21
34 OC ac Q 2045 80 25.5
35 a es Q 2286 79 29
36 ad ae 9 1747 78 22
37 a a Q 1626 77 21
38 ae a °) 1656 77 21
39 Sy e 9 974 76 13
ek Saas - 2 960 75:5 13
4! ae os Q 1187 73 16
42 a Ԥ 9 1106 72 15
43 as “ 2 1760 72 24
44 a S Q} 1942 72 27
45 OC we 2 1388 72 19
46 oy a Q| 1342 71 19
47 ? a 2 877 70 12.5
48 oC $ 2 1344 67 20
49 < K O 2E75 67 18
50 OC (Tail amputated.)| 9? 1880 61 31
5! et : =) § Aga 87 20
52 os ol —|cir 2000 87 23
53 ne 7 iy mega 83 21
54 a as — 2180 82 26
55 os Os —| 1180 82 14
56 4 a —| 2020 73 28 |
57 es J — 1621 72 22
1|Macacus cynomolgus, 2 1567 67 23
2 ee ue a 2070 62 33
3 ae ss 3B 2060 62 33
4 “6 “6 3 918 59 16
5 a oC juv.| ¢ 582 50 12
6 ee ie juv.| g 420 44 9-5
7 “ «s juv.| ¢ 540 44 12
8 ag “ co) 1203 100 12
9 a ae juv.| 9 919 62 15
10 = Q| 1803 54 33
11 a ts ce) 1497 53 28
12 a a fe) 1142 52 22
13 “ ve Q 1126 47 24
14 as fs — 1231 62 20
1;Macacus nemestrinus, ay 8500 128 66
2 oe ae o 8610 122 7t
3 os ne é 5610 119 47
+ > ca g 4590 118 39
5 ae a6 a he 113 pene ry SN
6 as as g 6620 105 63
7 ti ee ce) 2287 103 22
8 a OC ce) 3580 100 36
9 i i 2 3100 95 32
10 “so “c fe} 2S ee 84 we eee
1|/Macacus sinicus, a 1340 75 18
2 fs s By 848 68 12.5
3 * g 793 58 12
4 “ ' as fe) Tie ees 70 ui secooeee
5 “6 46 ae (een Leb. 67 fe
1|Macacus pileatus, a 1190 60 20
SpitzKa, Brain-Weights of Animals.
QUADRUMANA
| ee
2)Macacus pileatus,
3 aa oe
4 6 “6
1|Macacus speciosus,
2 “6 6
Macacus melanotus,
1\Cynopithecus niger,
2 46 *6
juv
3
1|Cynocephalus babouin,
2 oe 6
Cynocephalus hamadryas,
46 ae
“a a6
juv.
juv.
© CONF ANN PW WD Hint Ww
1|Cynocephalus anubis,
2 46 6
Cynocephalus mormon,
Cynocephalus sphinx,
Cynocephalus leucophezus,
Mycetes cavaya,
Mycetes ursinus,
Ateles beelzebub,
Lagothrix humbcldti,
1|Cebus capucinus,
La} é
juv.
“6 “ce
“6 “6
“6 of
Cebus capillatus,
Cebus hypoleucus,
WR eH DH Binet WD
Cebus subcristatus,
Cebus annellatus (Vertex
root of tail 42 cm.)
Cebus albifrons,
Chrysothrixz sciureus,
Nyctipithecus comm.,
Hapale penicillata,
1\Jacchus vulgaris,
“6 a6
Ww wb
Sex
Ratio:
Brain-Wt
Body—W’t|Brain-Wt| =1
Grams Grams
2.1357 72 19
2 1403 64 22
2 1801 62 27
2 1262 57-5 22
gd} 5560 98 57
2 942 81 I1.5
é 1105 80 14
é 6350 lag 58
g 5490 107 51
ES eee 96 |---- ----
o 3340 167 20
rs 3175 148 21
g 1545 109 14
Q| 2235 135 16
2 2414 128 19
o| 10230 199 51-5
2 3332 153 22
2 1678 136 12.5
2 1692 114 15
2 1572 U2 14
Q 1490 108 14
9} 3581 104 34
od eee HO} + jee yeee
—| 1100 96 11.5
2} 5000 152 33
Sees 167): |jsoaseeeee
2 1292 103 12.5
Q 2481 135 18
2 1718 124 14
3 826 45 19
Q}| 1025 19 54
2 1870 © 97-5 20
— 4850 112 43
Gi 2030 79 26
oS 1083 76 14
a 1812 Jo 26
cg 111g 58 19
2 1223 68 18
é 1370 69 20
_— 1660 77 21.5
maf os O75) plese eS
dll 1672 59 11.5
co 504 50 10
g 585 54 I!
ry 902 71 13
to|(without int’s-
g |tin’s) 1490 69 22
dite i675 58 12
& 2410 22 109
eee a AYES eee eee
Q 206 8 26:
Bs 320 8 40
ry 204 7 29
Q| 270 9 30
298 8.5 35
13
14 JourNAL OF COMPARATIVE NEUROLOGY.
Ratio:
Brain-Wt
No QUADRUMANA Sex|Body-W’t} Brain-Wt| =I!
ey Grams. | Grams.
5|Jacchus vulgaris, _ 204 9 23
6 “ “ — 150 Yi 21
7 “ “ nae 207 7 27
8 “ “a = 105 7 15
Midas ursulus (rufimanus) 9 361 24 15
Lemur bruneus, Pa 1505 26 58
Nycticebus tardigradus, By 612 13 51
Carnivora.
1/Ursus americanus, g| 25990 248 105
2 “6 a6 & pete. AO OA 192 eos
1|Nasua rufa, juv.| gf 719 35 20
2 “6 “6 juv. a Ae ea es 30 pa
3 “é ac 2 3200 41 78
Alte a? as ; ce) 2165 32 66
Gi a juv.| 9 1127 29 39
Lutra vulgaris, gt 2215 39 57
Bassaricus astuta, ae 842 19 44
1/Vulpes fulvus, juv. Be 3070 49-5 61
ae “ juv-| Q] 3458 53 65
Felis tigrina, Q 1989 63 31
Zalophus californ. (Gillespie) | —]--------- 335 = «|---------
Rodentia.
Arctomys monax, 2 3051 II 277
1|Dasyprocta agouti, >) Paeenne ee 10) lene
2 . f z 1803 19 95
6 ‘6 ‘2 ae 2935 21 133
1|Cynomys ludovicianus, é 392 7-5 52
2 “a “ fe) 504 7 72
Ungulata
Equus caballus, o) Ee ae 51925, |= seneee
Dicotyles tajacu, 9 7930 74 107
Auchenia glama, 2 (eee 222). ||-=asseeee
Edentata.
\Myrmecophaga jubata, | 2 | 18940 84 225
Tamandua bivittata, 2 930 | 21 | 44
Marsupia lia.
Didelphis virginiana, = ee ee | ; Mb osc
{Petrogale xanthopus, | 25 2441 23 | 106
SpitzKa, Brain-Weights of Animals. 15
The following list contains the fresh weight of the body
but not of the brain, this organ having been removed some
time after a zinc chlorid solution had been injected into the
body :
Zn Cl2
Sex| Body-W’t}Brain-W’t
Macacus rhesus, 1866 97-5
“ as 2069 86
“6 “6 1490 85
‘es 66 1640 80
«6 ‘6 805.5 78
46 66 978 69
Cercocebus albigena, 1991 76
Cercocebus fuliginosus, 2561 94
Gercopithecusreallitrichusys) 130), econ eeee 65
“cc “cc 1629 75
Cebus albifrons, 1640 80
Cebus capucinus, 1409 69
ANALYSIS OF 80 FRESH BRAIN-WEIGHTS OF THE GENUS MACACUS.
Macacus rhesus. Among the 57 specimens there are 25
of males, the same number of females, and 7 of which the sex
is not recorded. The body-weight is wanting in the case of
one of the males. Twenty of the males weighed over 1000
grammes each, and 22 of the the females. Only one of these,
a male weighing 5190 gms., with a brain-weight of 93 gms.,
can be considered a full-grown adult; the ratio is 1:56 and is
doubtless much nearer the true adult ratio than any of the
others in the list. The cases are tabulated according to sex,
and average brain- and body-weight in the following table:
TABU «iL
Macacus Rhesus.
Total Total Averages.
No. of )Range of Body-| Body- Brain- Body- Brain-
Sex. Cases Weight. Weights. |Weights. | Weight. | Weight.
Males 20 (1079-5190 gms)| 34926.0 1615.5 1746.3 80.77
1 4 |( 744- 912 “* )| 3448.0 303-0 861.0 75-75
Females 22 (1106-2286 ‘* )| 35659.5 1725.0 1620.9 78.40
“ 3 ( 877- 974 ‘* )| 2811.0 221.5 937.0 73.80
(?) 7 j(1180-2180 ‘* )| 12485.0 566.0 1783.4 80.90
Male I | Wee a see saan coaloneeen ees Te OM eee oe 72.00
16 JOURNAL OF COMPARATIVE NEUROLOGY.
Ratios of Body-weights and Brain-weights.
(Brain-weight =1.)
Total of 56 cases, I 20816:
20 Males (1079-5190 gms.) I's 21562:
22 Females (1106-2286 ‘‘ ) I? 20:672
Macacus cynomolgus. There are 14 specimens of this
species, 7 of males, 6 of females, and 1 of unknown sex.
None of these, to judge by the body-weight, were full-grown
animals. The highest brain-weight, 100 grammes, is that of a
female weighing only 1203 gms., a case which must for the
present be regarded as exceptional. The average weights
range between 50 and 67 gms. for the larger animals of the
series.
TABLEMIE
Total , Total Averages.
No. of |Range of Body-| Body- Brain- Body- Brain-
Sex. Cases Weight. Weights. | Weights.| Weight. | Weight.
Males . 3 (1567-2070 gms){ 5697.0 191.0 1899.0 63.7
a 4 ( 420- 918 ‘** )| 2460.0 197.0 615.0 49.2
Females 5 (1126-1803 ‘* )} 6771.0 306.0 1354.2 61.2
“6 1 ( 919) 919.0 62.0 919.0 62.0
(?) I (1231) 1231.0 62.0 1231.0 62.0
Ratios of Body-weights and Brain-weights.
(Brain-weight =1.)
Total of 14 cases, I 3/20,8 72
3 Males (1567-2070) I 1 20,82:
5 Females (1126-1803) I 3.220 as
Macacus nemestrinus. In eight of the ten members of this
species the body-weight had been noted (5 males; 3 females.)
Two of the males, weighing respectively 8500 and 8610 gms.
have brains weighing 128 and 122 gms., giving ratios of 1 : 66
and 1: 71.
TABLE IV.
Total Total Averages.
No. of |Range of Body-| Body Brain Body Brain
Sex. Cases Weights. Weights. | Weights.| Weight | Weight.
Males 5 (4590-8610 gms)} 33930.0 592.0 6786.0 118.4
Females 3 (2287-3580 ‘* )' 8967.0 298.0 2989.0 96.0
SpitzKA, Brain-Weights of Animals. 17
Ratios of Body-weights and Brain-weights.
(Brain-weight—1.)
Total of 8 cases, Fo7540. 20;
5 Males (4590-8610) ey Mee
3 Females (2287-3580) erie fe
Other Spectes of Macacus. Five specimens of M. sznicus,
the same number of J. pileatus are all too young to furnish
reliable ratios. The average brain-weight of MW. sénzcus (maxi-
mum 75 gms.) is 67.6 gms. Of M. pileatus (maximum 72
gms.) is 63.1 gms.
An adult specimen of WM. sfeciosus (3) weighing 5560
gms. has a brain-weight of 98 gms., giving a brain ratio of
1:57. The brain of a young specimen (?) weighs 81 gms.
A single specimen of J. melanotus has a brain-weight of 80
gms.
Judging from these records and allowing for disturbing
factors, the following tabulation of the absolute and relative
brain-weights, with their variations, may be here proposed.
The sexual differences are not discussed at present, for the
number of adult specimens is far too small for accurate analysis.
Asa rule, however, the females seem to have a smaller brain-
weight, both absolutely and relatively, although the reverse
would appear to be true were the total of the tabulated cases to
be alone considered.
The list of ‘‘ Probable Averages” in Table V is only
tentatively proposed, for the accession of a larger number of
adult specimens may materially change certain of the figures.
Bie Bei.
PROBABLE AVERAGES OF BRAIN-WEIGHTS IN THE GENUS MACACUS.
Probable Ay-
erage Brain-
Probable Av-
Usual Range of erage Adult
Brain-weight. weight. Ratio.
Macacus rhesus, 70— 90 gms. 80 gms. Tc5s
“«« cynomolgus, 50- 70 *§ Gouss I: 50?
Ks nemestrinus, 95-120 ‘ LILO ee 170
to sinieus; 65-75 <* 70; <é ?
J pileatuss 60- 70 ‘< 65s I: 50?
‘« _speciosus, 80-100 ‘ gone. I: 60
Lee, Say
A DESCRIPTION OF CHARTS SHOWING THE AREAS
OF THE CROSS SECTIONS OF THE HUMAN
SPINAL CORD AT THE LEVEL OF EACH SPINAL
NERVE.
By Henry H. Donatpson anp Davip J. Davis.
(From the Neurological Laboratory of the University of Chicago.)
A. CURVES SHOWING THE AREA OF THE CROSS-SECTION OF EACH
SEGMENT OF THE MATURE SPINAL CORD.
Introduction.
The data which are presented in this paper were gathered
for the purpose of preparing a curve based on the human
spinal cord, with which to compare the areas of white and gray
substance found in the cross sections of the spinal cords of
other mammals. Reference to the literature shows that
with the exception of the curve presented by KrausE and
AGUERRE (1), which was published while this study was in pro-
gress, the series of curves appearing in the text-books and used
to show the areas of the gray and white substance at different
levels of the cord, was first introduced by WoroscuitorF (2),
- while that investigator was making a study of the conduction
paths in the spinal cord of the rabbit. _WoRoSCHILOFF’s curves
were based on measurements published by B. STILLING (3).
The fact that the records which WoroscHILOFF chose as
‘the basis for his curves were froma child of five years, and
therefore from acord not completely developed, has been re-
cently pointed out by several writers. That WoroscHILOFF
‘should: have used these particular records of STILLING, instead of
» taking the records for mature cords, published in the same vol-
20 JouRNAL OF COMPARATIVE NEUROLOGY.
ume, is explained by the fact that only in the case of the five-
year old child are the areas for the separate funiculi given, and
his interest was at that time directed to the funiculus lateralis.
Since the white substance in the cord of the five-year old child
is, both absolutely and proportionately, less than in the adult, the
use of this series of curves to illustrate the gray and white sub-
stance in the mature spinal cord is necessarily misleading, yet
these curves are at present employed in the text-books, without
any accompanying statement to show that they are based on
the measurements from an immature cord.
It is intended in this paper to present a chart which shall
more accurately show the true relations between the gray and
white matter as they appear in the adult, and thus shall replace
the older charts now in use. In order to do this, not only
should the measurements of the areas be those from the adult
spinal cord, but there is another correction which applies to all
the charts thus far published, including that of Krause and
AGUERRE (1), and which consists in representing the segments
of the cord in their true lengths.
I. Representation of the Length of the Segments.
Heretofore, in these charts, the abscissa has always been
divided into 31 egual parts—each part representing the length
of a segment of the spinal cord. Manifestly this will give an
incorrect form to the curve, because the segments of the cord
are really of unequal length.
As any ordinate representing the area of a cross section
applies strictly to the sum of half the distance from it to the or-
dinates next above and next below the point at which it is
erected, it follows that by multiplying the areas represented by
any ordinate by the length of the cord to which it applies, we
get an approximation of the volume of the segment. It is evi-
dent, also, that the volume of a segment thus determined when
the divisions of the abscissa are equal, would be different from
that determined when the divisions of the abscissa represent
the segments in their true length. To make a correct con-
struction, it was therefore necessary to gather data on the
DonaLpson AND Davis, Human Spinal Cord. re
lengths of the segments of the spinal cord. The measurements
of these lengths recorded by STILLING (3, p. 619), are insuffi-
cient, having been made between the uppermost and lowest
fila of each nerve—thus omitting some of the cord, where, as is
conspicuously the case in the thoracic region, the line of roots
is not continuous. A number of fresh observations were there-
fore made. The measurements to determine the lengths of the
segments in the adult human cord were made on one specimen
(W)—preserved in normal size in 10 per cent. formalin;—on the
two careful delineations (X, Y) published by Kany (4), and on
the photolithographic chart (Z) of RipINGER (5). In the three
plates the cord is depicted in natural size. The cords in the
order named, are designated W, X, Y, Z.
In the cord W, the condition of the specimen did not per-
mit the measurement of the first four cervical segments. In
cords X and Y, the first cervical segment could not be mea-
sured on the dorsal aspect nor on the coccygeal segment at all.
In cord Z, measurements on the dorsal aspect alone could be
made, and even these could not be extended below the level of
the 12th thoracic segment.
To determine the length of a segment, the distance be-
tween the uppermost fila of successive nerves was found, begin-
ning with the uppermost filum of the first cervical nerve.' This
was done both on the dorsal and ventral aspects of the cord.
In making the measurements, the distance was marked off with
a pair of spring compasses, and then this distance was measured
on a metal scale to the nearest tenth of a millimeter. Each
measurement has been separately entered in Table I.
1This method of measurement credits to any segment the entire ‘‘inter-
segmental space’’ which lies caudad to it. The method of LUDERITZ (6) was
to credit to any segment one-half the length of the intersegmental spaces lying on
either side of it. The difference in the results would be the amount by which,
in any instance, the intersegmental space caudad to the part of the segment to
which the roots were attached differed in length from the sum of half the inter-
segmental spaces above and below the same parts. This difference in general
would be small.
22 JOURNAL OF COMPARATIVE NEUROLOGY.
TABEE. 1:
Showing in millimeters the lengths of the segments in the adult
human spinal cord.
Segment Cord W Cord X Cord Y Cord Z Average
Aspect Dorsal Ventral|Dorsal Ventral|Dorsal Ventral Dorsal
(1 5-9 8.2 7.6 7-23
| 2 Holly i iPe8) 6.0 13.0 10.4 9-74
"eta 12.2 11.0 | 12.0 13.1 13.8 12.40
: | 4 GHP Seige iy nS 18.1 14.34
& 15 TOSG, Lie 7 ish eMicey dl SyLfoy ste 13.9 12.35
.S) | 6 14-3 140 13-7) 14-0) | ange ia 13.5 13.75
7 T2254. 1226) 0522) OLS eenico 13-7 12.85
L8 12:6) 91'5.7 15-6 3033006) e227, 12.1 13.20
{1 122) a 146) ig s7a ate 9.3 13.4 12.80
2 [2:90 1405 12:95) W523) eksese wake 16.1 14.20
| 3 Hie7 t= Foe) 18.8 18.8 | 15.6 "16.4 16.6 17.30
4 16.7. 20.2 21.0) 1953\7|| 24269200 24.3 20.90
LOR is 19.8 19.9 20:3 20.5 | 23-6) 26.0 22.5 21.85
2} 6 25°83". 26.6) °} 24.1! 22:21 arog eek 21.9 23.55
8 7 287 28.8 1723), 20.7 2o:Aw zee 23.8 24.22
ayiile ce 29:6))28:3 19:8) 1120.05 |)28.0 sezaeo 23.9 25.05
9 22:8) 23.3 19:0, (22-44) 2458) 626.3 25-7 23-50
| 10 22.7) 2564 19,7.) S20 sul O-Oreekee 26.2 22.50
II 280 20.1 19:1") | 20.43) ) 2335 Qee 19.2 21.38
er2 20.2 20.9; |(20.3,. F3.9 |/2h.50 19-5 19.60
eal 21-3 23-0" | 1595) 0427) 10.3 akoe2 18.30
g\2 R54 937 VO) 1955 i] is Omen mnO 12.90
g13 13-2) 114-0 III Onja| MOS) ak25 11.80
3 [3 YO2S0) LEO 10,7 728) || LOIQy Lies 10.64
5 9.1 7.2 10.5 6.2 9.9 6.1 8.16
I Vols 8.4 10.3 Bay 8.6 6.1 7.74
S| 2 6.1 6.6 9:6, > “4 .5n\org.4 8.3 8.40
943 6.6 4.4 8.4 4.8 8.3 9-9 7.07
nN |14 6.1 6.6 5-4 4-7 8.5 8.6 6.65
5 6.6 4.1 3-3 38 | 4.9 5.9 4:77
41 2.5 2.50
Coccygeal
The last column in the Table (I), gives the average of all
the measurements for each segment, and these average lengths
were those used for the divisions of the abscissa in the accom-
panying chart I.
(a) Total Length of the Spinal Cord. The lengths of all
the segments taken together, should, of course, equal the
length of the entire cord. The average length obtained for the
segments will therefore depend on the lengths of the cords. But
before presenting the lengths of the cords which were here ex-
LE EE
DonaLpson AND Davis, Human Spinal Cord. 23
amined, it will be best to state what is already known concern-
ing the length of the human spinal cord.
The correlation in development between the medulla
spinalis and the columna vertebralis indicates that the longer col-
umna vertebralis would contain the longer medulla spinalis.
The observations of RAVENEL (7) on the length of the adult
human spinal cord, show in 11 adult males, a range in length
of 390-480 mm., with an average of 448 mm. In 11 adult fe-
males, the range is from 370-460 mm., with an average of 413
mm. _ These results plainly exhibit the greater average length
of the medulla spinalis in the male. The measurements were
made on fresh material from the level of the upper edge of the
atlas to the lowest filum of the coccygeal nerve on the conus
medullaris.
The cords examined for the length of the segments in the
present investigation give the following lengths:
TABLE II.
Cord Sex Length in mm.
WwW Male 458
Xx ? 403
Y ? 453
Z Male 448
Average, 440.5
It is thus seen that this average length lies between the av-
erage length for the males and that for the females, though
rather nearer the former, as determined by Ravenet (7). It
concerns us here, however, merely to show that the average
length obtained is a medium one—differences according to sex
being disregarded. The average lengths of the segments deter-
mined from the several cords (W, X, Y, Z) are presented in
Table I. | When these average lengths are summed, they give
441.6 mm., for the length of the cord, against 440.5 mm., as
determined by direct measurements. The former number is
the one employed in the construction of the chart.
LUperiTz (6) is the only investigator who has made a de-
tailed study of the length of the segments of the spinal cord.
On comparing the results just given (Table I), with those
24 _ JouRNAL OF COMPARATIVE NEUROLOGY.
obtained by Liperirz (6), it appears that the averages of the
sums of the segments in: his two men—33 and 37 years of age
—show the total to be 450.5 mm., or about 2% more than the
total sum in our case. This is a difterence which is well within
normal limits, since the measurements of RAVENEL (7) show for
the male cord a range in length from 390-480 mm. At the
same time, the lengths of the segments as determined by LU-
DERITZ, agree substantially with our own, when the differences
in the total length of the cord and the great individual varia-
tions in the lengths of the segments are both taken into ac-
count.
This can be shown by the accompanying Table (III), in
which the percentage values of the lengths of the different
regions of the cord as determined from our own Table (I), and
from the observations of LUDERITZ on two male cords, are com-
pared with the range in the lengths in these regions, as found
by RAVENEL in II male cords.
TABLE III.
To show the percentage value of the lengths of the spinal cord within
the regions named in the table, as compared with the range in
these percentages as determined by RAVENEL.
From Table (I) Liideritz Ravenel
Region. 2 males, 2? 2 males, p. 460 II males, p. 348
Cervical 21.7% 24.1% 19.8-25.0%
Thoracic 55:8% 54-9% 53-2-65.4%
Lumbar 13-9% 11.3% 9.1-13.6%
Sacral and Coccygeal 4% 9.6% 1,8-15.2%
For these reasons we are justified in employing our own
data in marking off the abscissa for the curve showing areas,
since, in so doing, we shall give an approximately true picture
of the relations in the human cord of medium size.
For the abscissa, it was decided therefore to take 441.6
mm. and this base line was divided into lengths equal to the
average lengths of the segments as recorded in Table I.
Il, Areas of Cross-Sections.
In the first instance charts were drawn life size, so to speak,
with the abscissa 441.6 mm. long. The ordinates were drawn
DoNnALDSON AND Davis, Human Spinal Cord. 25.
on a scale of one linéar millimeter for each square millimeter in
the area of the transverse section of the cord. The original
charts thus made, were too large to publish, and have therefore
been reduced photographically to exactly one-third their linear
dimensions. As a consequence of this reduction, multiplying
the length of the ordinates in the accompanying chart by three,
will give a line as many millimeters long as the section has
square millimeters of area, and multiplying the length of any
segment in the chart by three will give the length of the seg-
ment as represented in the column of averages in Table 1.
The data for the areas of the cross sections represented by
the ordinates were taken from STILLING (3) and comprise his.
measurements on four adult cords.
TABLE IV.
Giving the pages in STILLING’s ‘‘Neue Untersuchungen iiber den Bau
des Riickenmarks’”—1859, where the records are to be found.
Designation
of Curve. Sex. Age. Pages.
A Male 45 years Page 1098
B Woman 35 years Page 1100
Cc Woman 25 years Page 1099
D Male 25 years Page 1097
The sections from each segment of these cords are also
depicted in Table XXVIII of Sritttne’s Atlas (1859).
This is the place to call attention to the condition of the
cords measured by Stitiinc. All of the measurements of
areas used in this present article—including those on the imma-
ture cords to be mentioned later on—were made on material
hardened in chromic acid and preserved in 97% alcohol.
STILLING makes a statement of his method on pp. 1032 and
1033, but it appears to be erroneous in that it calls for so large
an amount of chromic acid, practically an 8% solution. Pre-
liminary observations made on the spinal cord of the white rat,
hardened in chromic acid 0.6%, followed by 97% alcohol, in-
dicate a slight increase in the volume of the cord after this
treatment. This suggests that these measurements by STILL-
26 JoURNAL OF COMPARATIVE NEUROLOGY.
ING may give a somewhat greater area than would appear in
the fresh cord.
Although the exact effect of STILLING’s treatment has yet
to be determined, it is not to be anticipated that more than a
small correction will need to be made for it, and as the several
cords used were all treated by the same method, they are com-
parable among themselves.
In accordance with the measurements of STILLING, three
curves were constructed for each individual. These curves rep-
resent his determinations for the total areas of each section, as
well as the areas of the white and the gray substance, taken
separately ; all measured at the most caudal level of each segment.
To obtain a general expression for these several measure-
ments, a composite curve—the first on the chart—was made
from the averages of the four individual records.
This composite curve shows the maximal total area of the
cord to occur at the VI cervical segment, the next greatest areas
being at the III lumbar and V Lumbar, a result dependent on the
large area of the white substance in C VI, of both gray and
white in L III; and of the gray in L. V.
B. ON THE VOLUME OF GRAY MATTER IN THE SEVERAL SEGMENTS
OF THE CORD.
A special feature of this chart as now plotted, is that it
enables us to estimate the volume of gray substance belonging
to the several segments. This volume was determined as fol-
lows:
For the first segment we multiply the number of square
millimeters represented by the ordinate, by the number of mil-
limeters representing the length of the segment. In the case
of the first segment of the cord, the result is probably a trifle
too large. Below the first, we can make a more accurate de-
termination of the volumes by using to represent the area one-
half of the sum of the two ordinates limiting each segment; this
area being multiplied by the length of the segment intervening.
Working in this way, the following results have been obtained
for the average volumes of gray substance in the segments of
the cord as exhibited in the composite curve on Chart I.
DonaLpson AND Davis, Human Spinal Cord. 27
TABLE V.
Giving in cubic millimeters the volume of the gray substance in each
segment of the mature human spinal cord. With the exception
of the first cervical segment, the volume is obtained by multiply-
ing one-half the sum of two limiting ordinates by the length of
the intervening segment, based on the data used for the composite
curve in Chart I.
Volume in Volume in
Segment cubic mm. cubic mm.
Cervical I 129
II 157
III 178
IV 220 )
AG 224 | Cervical segments IV-VIII
VI 275 1220
VII 261 [
VIII 240 J
Thoracic I 177
Il 147
Ill 14!
IV 148
Vv 171
VI 198
VII 180
Vill 159
1X 156
Xx 169
XI 178
XII 187
Lumbar I 216 )
II 184 | Lumbar segments I-V.
III 228 $ 1086
1V 256
Vv 202 |
Sacral I 192
II 176
Ill 105
IV 67
Vv 34
‘Coccygeal iT 12
An examination of the foregoing Table V shows some re-
lations worthy of remark. In the first place, the greatest vol-
ume of gray substance is here found in the segment C VI. In
the last five of the cervical segments, the total volume of gray
substance is 1220 cubic millimeters, being thus decidedly
greater than the volume of substance in the five lumbar seg-
ments, which contain but 1086 cubic millimeters.
28 JOURNAL OF COMPARATIVE NEUROLOGY.
Between the two intumescentiae of the cord, the segment
with the smallest volume of gray substance (T III) contains 141
cubic millimeters, which is more than half that in the largest
segment, C VI, which contains 275 cubic millimeters.
This shows first, that there is much less difference in the
total amount of gray substance in the successive segments of
the spinal cord, than would appear by comparison of the areas
of their cross sections alone (see composite curve in Chart 1);
second, that as a matter of fact, it is the cervical enlargement
which contains the greatest volume of gray substance although
the area of the gray reaches its maximum in the lumbo-sacral
region. It may not be out of place to again call attention to
the fact that the division of the base line into equal intervals
for the successive segments of the cord, as in the charts based
on WOROSCHILOFF’S curves, gives a set of relations which are
misleading ; for it necessarily suggests that the volumes of the
segments are proportional to the areas of their cross sections.
Cc. RELATION BETWEEN THE AREA OF THE CROSS SECTION OF
EACH SEGMENT OF THE CORD OR THE VOLUME OF GRAY MAT-
TER IN IT, AND THE AREA OF THE CROSS SECTION OF ALL THE
NERVE ROOTS BELONGING TO THE SEGMENT.
LUpERITz (6), p. 478, has published a chart based on
STILLING’S measurements, which shows the relations between
the combined areas of the cross sections of each of the
four spinal nerve roots, and that of the _ cross
section of the gray substance of the segment to
to which they belong. The two curves representing the two
series of areas run nearly parallel to one another. The data,
however, on which the curves are based, are not exactly com-
parable, for a reference to STILLING (p. 392), shows that the
areas of the cross sections of the nerves were taken from mea-
surements in the case of a woman of 26 years; whereas the
areas for the cross sections of the gray matter of the cord were
from a five-year old child. | We have drawn a second curve in
which the areas of the gray matter for the mature cord as rep-
resented in Table VI, are used. This curve does not fit quite
DonaLpson AND Davis, Human Spinal Cord. 29
so closely that for the areas of the nerves, as does the curve
based on the areas of the gray substance in the five-year old
cord. Especially in the thoracic and lumbar regions, the area
of the gray substance is larger in proportion to the cross sec-
tions of the nerves than in the case of the young cord. In gen-
eral there appears to be in the mature cord, as contrasted with
that of the child, a shift of the larger areas of the gray substance
one or two segments cephalad. As a consequence, therefore,
using data derived entirely from mature individuals, the curves
are less similar than the figure of Liprrirz (Fig. 2, p. 478)
would indicate.
If we now compare the relative development of the volumes
of the successive segments of the cord, with the areas of the
cross sections of the spinal nerves, we find that while there is a
fair correspondence in the cervical and in the sacral regions,
that in the thoracic and upper lumbar regions, where the seg-
ments have grown most in length, a great disparity exists be-
tween the volume of the gray substance and the area of the
cross sections of the nerves, the gray substance being much
more abundant than we should expect. This suggests that in
these localities, the lengthening of the segments, and conse-
quent increase in the volume of the gray substance, is merely
one of adaptation to the elongation of the vertebrae, and not
accompanied by any corresponding increase in the complexity
of its structure.
D. GROWTH CHANGES.
I. On the Areas of the Cross Sections of the Several Segments
of the Spinal Cord at Different Ages.
For this comparison we have used as a standard the rec-
ords which were employed for the composite curve in Chart I.
As previously explained, the data for this composite curve were
obtained by taking the average of the observations on the four
individuals used for the construction of curves A, B, C, D re-
spectively of Chart I. The numerical data are given in the
column headed ‘‘Mature”’ tn Table VI.
To compare with the composite curve we have from
30 JOURNAL OF COMPARATIVE NEUROLOGY.
STILLING a series of measurements of the areas of the gray and
white substance at the level of the several segments of three
immature spinal cords: from a child at one year, from one at
two years, and from one at five years. STILLING’s tables con-
taining these records are found on pages IIOI, 1102, 339 and
343 of his ‘‘Neue Untersuchungen tiber den Bau des Riucken-
markes.”” 1859.
In the following Table (VI) which contains ST1LLiNne’s mea-
surements, it is at once seen that certain segments in the five-
year old child were not measured. In order to make this table
comparable with the others, an interpolation for the missing
records, C I and C II and LI and LII, has been made on the
assumption that in the five year old cord the areas of the un-
measured segments would form the same fraction of the sum of
all the areas that they do in the one and two year old cord.
At the foot of the five year old columns in Table VI, the total
given is the one obtained after the above interpolation. More-
over, it will be noted that in this cord identical measurements
are given for the thoracic segments T.III-VIII and T.IX-XI.
Individual measurements for these several segments would,
of course, have been preferable, but there is no reason to sus-
pect that any serious error has resulted from the method here
employed by STILLING.
DonaLpson AND Davis, Human Spinal Cord. 31
TABLE VI.
Areas of Cross-Sections of the Human Spinal Cord at Different Ages.
The records for the cords at 1, 2 and 5 years are copied from
STILLING. The record for the cord at maturity gives the aver-
ages of his four tables of measurements on adults.
Areas of White Substance. Areas of Gray Substance.
sq. mm. sq. mm.
Age. Age.
Segment. Tyr. 2yrs. 5 yrs. Mature.|I yr. 2 yrs. 5 yrs. Mature.
Cervical.
I B04 0307/5 esa bn O2-O2) 07-07) 7h 4-2 meme UT 7.8
II 28.98| 30.04 5B:p4 68.57| 4.60| 4.60|1_ 12-37 ite
Ill 22.62| 23.33 32°75|) 72-37. 4-60] 4.60 11.25) 14.14
IV 48.08) 41.36 34.65! 74.94] 18 03] 16.26 12.73| 16.52
Vv 45-60] 41.36 42.02| 73.97| 21.21] 16.26 19.67| 19.70
VI 46.31} 37.12 42.02} 79.18} 20.86] 20.85 19.67| 20.32
VII 47-37| 43-83 40.39] 71.84] 18.03] 14.14 18,24] 20.38
VIII 39.24] 46.66 33-99| 65.30) 16.97] 12.37 13.68] 15.99
Thoracic.
30.75] 30,04 28.59] 63.65] 6.01] 6.36 6.97] 11.66
II 26.51} 26.51 24.12} 53-64] 6.72} 7.78 5-32] 9.01
III 20.85} 28.99 24.12} 52.23] 4.95| 6.36 eel) AG /he7l
IV 21.56] 26.16 ZANE 252222) beso eAsO5 5-32} 6.89
V 22.98] 20.50 24.12] 50.10] 5.30) 6.01 5-32} 38.74
VI 21.56| 22.98 24.12} 45.20| 4.60] 6.36 5-32| 8.04
VII 19.44] 24.04 24.12| 47.43) 5.66) 5.30 5-32] 6.80
Vill 20.86) 20.50 24.12] 45.15} 6.01] 5.30 5-32] 5-92
IX 20 15| 20.85 23-83] 40.74] 5.66) 7.78 4-56] 7.33
X 23.68] 16.97 23-83} 43-05] 4.95] 7.07 4.56) 7.71
XI 23.68] 23.33 23.83] 41.40] 6.36) 7.07 4.56) 8.92
XII 22.62} 20 85 21.74] 44.18] 7.42] 7-07 6.44] 10.14
Lumbar.
I 22.98) 28.33); (cp cat 44-00) 7:42]. +6.54 13.51
i 22.62| 23.68 1 ese 49.6:| 10.96} 9.90 yee rae
III 22.98) 19.09 21.15} 48.01] 14.85) 16.61 13.26] 23.59
IV 23.33| 22.62 22.34) 43-3c! 15.20 15.91 21.02] 24.48
Vv 20.15| 19.80 17.07| 43.4C] 17.68] 19.80 24.89] 25.01
Sacral.
I 22.62} 20.86] ° 17.18) 32.34] 15.91] 21.56 23.53| 24.47
II 20.85| 13.79 17.26] 19.44] 18.38] 22.62 23.22| 17.41
III 10.61] 10.61 9.87| 12.25] 15.20] 13.43 17.21] 12.19
IV 10.61} 5.66 5-97, 8.30] 9.19] 8.84 10.81| 7.86
Vv 3.89; 4.59 2.18) 4.77) 4:60) | 3:89 6.01; 6.36
Coccygeal.
I 1.06] 1.77 96, 2.38) 2.83) 2.47 2.70] 3.18
Total 766.00] 741.97} 734-80/1455.07 312.53/318.48] 334.65] 410.93
In order to compare the records in Table VI, we use the
sums of the total areas of the section, obtained by adding the
sums of the areas of the gray and white substance, which are
tabulated separately.
32 JOURNAL OF COMPARATIVE NEUROLOGY.
TABLE VII.
Showing the sums of the total areas in the three immature and one
(composite) adult cord, as tabulated in Table VI.
Age. Sum of 31 Areas.
I year 1078.53 sq. mm.
2 years 1060.45 sq. mm.
5 years 1069.45 sq. mm.
Maturity 1866.00 sq. mm.
These figures show that from one to five years, there is
very little variation in the sum of the total areas. It ranges
from 1078.53 sq.mm. to 1060.45sq.mm. Since this difference
appears as a deficit in the two year cord, it is probably the ex-
pression of an individual variation. The extreme cases, 1 and
3 years, differ by less than 2%, whereas between five years and
maturity, there is an increase in the total area of the sections
of nearly 74%. From this it is inferred that the growtli changes
leading to the larger area at maturity occur at some time subse-
quent to the fifth year of life.
The analysis can be carried a step further by comparing
the relative areas of gray and white substance in the several
cases.
TABLE VIII.
To show the percentage values of the sums of all the areas occupied by
gray and by white substance at different ages.
White Substance Gray Substance
Percentage Percentage
Sums of Areas of sums of Sums of Areas of sums of
Age. in sq.mm. total areas in sq mm. total areas
I year 766.00 71% 312553 29%
2 years 741.97 70% 318.48 30%
5 years 734-80 69% 334-65 31%
Maturity 1455-07 78% 410.93 22%
A glance at this table shows that during the first five
years, the proportional value of the white substance in the sec-
tion is about 70%, whereas at maturity it reaches 78%, the
gray substance of course showing a correlated variation.
It appears then that from the first to the fifth year, there
DonaLpson AND Davis, Human Spinal Cord. 33
is little variation in the relation between the gray and white,
and that the change in this relation must occur at some period
‘after the fifth year.
In this connection, it is of interest to determine whether
the growth changes leading to the greater total area of the
cord segments at maturity are the result of a proportional en-
largement in the different regions of the cord. In order to de-
termine this, it is necessary to compute the percentage values
of the total areas in the different regions. The results of this
computation are shown in the following table:
TABLE IX.
Showing for both the mature and immature cords the percentage value
which is represented by the total areas of the segments that
constitute the cervical, thoracic, lumbar and sacral and coccygeal
regions respectively.
Region. Age.
I year. 2 years. 5 years. Maturity.
Cervical 39-05 36.86 36.60 37.92
Thoracic 31.85 33-86 33-18 36.30
Lumbar 16.52 17.02 17.42 17.69
Sacral and Coccygeal 12.58 12.26 12.80 8.09
100% 100% 100% 100%
From the foregoing Table IX, it appears that after the fifth
year, the proportional growth in area has been slightly more
rapid in the thoracic region, and less rapid in the sacral and
coccygeal, while in the two intumescentiae, the relations at ma-
turity are similar to those found during the first to the fifth
year of life. From the end of the first year then, the relative
areas of the different regions of the cord change but slightly
during subsequent development. The statements which have
been made on the basis of the total area can also be repeated for
both the gray and the white substance separately, though it is not
deemed necessary to publish the computations, as the data for
them are found in Table VI.
It must be remembered, however, that from the first to the
fifth year of year of life, the medulla spinalis is growing rapidly
34 JOURNAL OF COMPARATIVE NEUROLOGY.
in length. From the measurements of RAVENEL (p. 350), we
have calculated that the length of the medulla spinalis at one
year of age would be about 200 mm., whereas he found ina
five-year old boy the length to be 300 mm. “Yet, despite this
increase in length, the measurements just given show that the
transverse diameters remain practically constant. Apparently
we have here another example of the tendency of structures to
grow first in their long axis before enlarging at right angles to
it. It must be remembered, however, that we are without ob-
servations on the changes which occur within the limits of the
first year. Y |
On looking at Table VI, it is to be noted that the area of
the white substance at maturity is nearly 95 % greater than it
was at five years, while the gray substance is only 23 % greater,
thus showing the much more rapid enlargement of the white
substance. This being the case, it is evident that the curves of
WoroscHILoFF, based on a five-year old child exhibiting in
cross section hardly more than half of the white substance in
its cord than is present in the adult, necessarily give a false no-
tion of the relations at maturity.
IT. Comparison of a Curve, Representing the Areas in the Chald’s
Cord, with the Corresponding Curve for the Cord of the Adult.
It has just been shown that from the first to the fifth year,
the areas of the cross sections of the spinal cord remain the
same size. It is therefore only necessary to obtain the mea-
surements of the lengths of the segments at some period within
these ages in order to construct a curve for the child’s cord that
may be compared with that for the adult.
Liperitz (p.471) gives the length of the segments in the
cord of a female child of three and a half years. His measure-
ments are presented in the following Table X.
DonaLpson AND Davis, Human Spinal Cord. 35
TABLE X.
Lengths of Segments of the Cord as Determined by Ltperirz in the
Case of a Girl of Three and a Half Years.
Segment. Length inmm. Segment. Length in mm.
a 4.7) ( I 8.25
cea Bey at Hee 6.25
| III 7-OY, err ae 4.5
Seg LW oP, fas |) NY 4.1
an V 8.6 4 V 2.9
El Vi 6.8
ee veut 6.3 I Bay
| VIII 53h el || 3-4
By ay LULL 3.8
pat g80 a WM 3.5
et 7.25 to) AY 3-0
| III 7.0
IV 8.9 3
aS) V 10.3 a I 3.0
3 | VI Litg. *O
5 1 VII 13.3
|
e | VIII nie 75
ee 6 1.5
anes 9.6
| XI 9.3
| XI 7.75
As will be seen from examining the table, the measure-
ment for the first cervical segment is lacking in the original rec-
ord, but it has been interpolated here on the assumption that
it would have the same proportional value as in the cord at
seven weeks. The measurements for a cord at this latter age
being given by LiUperirz (p. 470), it is possible to make a cal-
culation on this basis, and the result is the number which ap-
pears in the Table X. Upon adding the lengths of all the seg-
' ments together, we find the length of this cord at three and a
half years, to be 212.95 mm. For comparison with this result,
there is available RavENEL’s table (p. 550), giving the follow-
ing individual measurements for the length of the cord in
children.
'The length for the first segment is interpolated, being given the value
of 4.7 mm,
36 JouRNAL OF COMPARATIVE NEUROLOGY.
TABLE XI. (From RAveENEL).
Number. _ Total Length.
3 Boy of 2 years 245 mm.
4 Boy of 5 years 300 mm.
5 Girl of 9 years 280 mm.
From this comparison it appears that the cord here chosen
is short, the child evidently being under size even for a female.
However, the length 212.95 mm., is well within the probable
limits of normal variability as judged from the variations in the
length of the spinal cord in the adult. In using the curve,
however, it must be remembered that in this case, the lengths
of the segments are from a female cord that is probably short
even for this age and sex. This is all that need be said about
the baseline of curve E. Since the measurements for the areas
of the sections of the cord were so similar from the first to the
fifth year, it was thought best to choose those made on the two-
year old child (Table VI). This record of STILLING was taken be-
cause the measurements for all the areas are given, and because
it is the middle one of the series of three, and hence we know
the form and size of the cord before and after this period.
On examining curve E in chart I, it will be noted that the
intervals on the axis of ordinates ave egual to and have the same
value, as in all the other curves in this chart.
Special emphasis is to be placed on this point, and atten-
tention is particularly directed to it, since the designating num-
bers are smaller in size than those used for the other curves, in
which a number is given for each twenty units only. These
peculiarities create the illusion that the intervals on the axis of
ordinates in curve E are smaller than in the case of the other
curves, and for this reason, attention has been called to this
point.
On comparing curve E with the composite curve in chart
I, some interesting differences appear. If the composite curve
be taken as the standard, the following statements may be
made. The base line, or length of cord, in E is a little less
than half aslong. The total area (called entire section in chart)
at no point rises above 60 sq.mm., whereas in the composite
DonaLpson AND Davis, Human Spinal Cord. 37
curve, it runs above 100 sq¢.mm. The intumescentiae are more
abrupt. The enlargements of the areas in the intumescentiae
as compared with the areas in the thoracic region, are greater.
The maximum total areas in both the cervical and lumbar in-
tumescentiae are further caudad, and the absolute area of the
white substance is much less than at maturity. The most
marked deficiency in the areas of both gray and white sub-
stance occurs in the first three cervical segments, and especially
in the third cervical segment. That this last feature is not an
individual peculiarity, is indicated by the fact that the one year
cord in Table VI (the only cord available for comparison)
shows a similar relation. As the curve E is based on a single
individual, no significance can be attached to minor peculiarities
in it, but enough has been shown by the comparison just
made, to indicate that the cord of the child differs from that of
the adult in a number of its characters, and that the curves
showing the areas in childhood cannot be properly used to
show the relations obtaining at maturity.
Conclusions.
The foregoing observations warrant the following conclu-
sions :
The chart given in this article is more correct than that
based on the curves of WorRoSsCHILOFF, since the areas of the
gray and white substance are taken from measurements on the
mature spinal cord, and are plotted on a base line, the divisions
of which are proportional to the lengths of the spinal segments.
These curves show the greatest areas at the level of C.
VI, L. III, and L.V. The curves, however, are generalized, and
apply to a cord of medium size, the differences due to sex be-
ing disregarded.
Moreover, the measurements of the areas are from cords
which had been hardened in chromic acid, and preserved in al-
cohol. This treatment has certainly altered the size of the
cord, but control experiments indicate that the alteration in
size has probably been slight. A study of chart I (see Table
V) shows that the volume of gray substance in the intumescen-
tia cervicalis is greater than that in the intumescentia lumbalis.
38 JOURNAL OF CoMPARATIVE NEUROLOGY.
There is a general correspondence between the area of a
cross section of the gray substance at the level of any segment
and the area of the cross sections of all the spinal nerves be-
longing to the segment. When, however, the volume of the
gray substance, instead of the area, is used for the comparison,
a disproportionately large amount of gray substance is found in
the case of the thoracic and upper lumbar segments. This is
interpreted as indicating a passive enlargement of the gray
substance in these segments of the cords which have been most
elongated.
When the cords of immature individuals are compared
with those from adults, several important relations are brought
to light. In the first place, the sum of the total areas of the
cross-sections of the cords, from one to five years, is practically
the same (see Table VII), although during the period, a con-
siderable growth in length has occurred. During this time,
therefore, growth in the long axis has taken place without any
corresponding growth at right angles to the long axis.
The form of the cord from one to five years is nearly like
that at maturity, the difference being that in the mature cord
the relative enlargement of the areas of the cross-sections has
become greater in the thoracic region, but less in the sacral and
coccygeal (see Table IX). At maturity, the relative enlarge-
ment of the two intumescentiae is practically the same as at the
fifth year. From the fifth year to maturity, both the
length and the weight of the entire cord as _ well
as the area of the cross-sections at the level of the
several segments are increased. The sum of the areas of
the white substance at maturity is 98% greater than at five
years, and that of the gray substance 23% greater (see Table
VIII). This absolute increase must represent either enlarge-
ment of elements already completely developed, or the develop-
ment of elements still immature at the earlier age, or some
combination of both of these processes. Yet the failure of the
intumescentiae to increase in their relative area in the mature
cord (see Table IX), or in their proportional length (RAVENEL,
p. 350), would seem to indicate that during this period there
DoNALDSON AND Davis, Human Spinal Cord. 39
was no increase in their relative complexity; a result, which,
to say the least, was unexpected.
On comparing the curves for the areas of the cord at 3%
years (curve E), with the composite curve for the adult, in or-
der to determine the change in the form of the cord due to
growth, several important differences appear. In the child’s
cord, the total areas of the sections are of course less than in
the adult; the greater deficiency appearing in the substantia
alba. In the child’s cord, the intumescentiae are developed
more abruptly than at maturity, and the maximal areas appear
further caudad; yet, despite this, the sums of the total areas
in the cervical and lumbar portions of the cord have almost the
same relative values (see Table IX). The most marked de-
ficiency in the child’s cord appears in the areas of the first three
segments of the cervical region and especially in that of the
third cervical segment, while the entire thoracic region is less
developed than it will be at maturity. On the other hand, the
sacral region is arrested in its later growth and becomes rela-
tively smaller.
BIBLIOGRAPHY.
(1) Krause, R und AGUERRE, J:
Untersuchungen iiber den Bau des menschlichen Riickenmarkes mit
besonderer Beriicksichtigung der Neuroglia. Amatomischer Anzeiger.
Bd. 18, 1900.
(2) WoROSCHILOFF:
Der Verlauf der motorischen und sensiblen Bahnen durch das Lenden-
mark des Kanninchens. SBerdchte berate Verhandlungen der Koniglich
Sachsischen Gesellsch. der Wissenschaften zu Leipzig. Bd, 26, 1874.
(3) STILLING, B:
Neue Untersuchungen iiber den Bau des Riickenmarkes. Casse/, 1859.
(4) Kapyi, H:
Ueber die Blutgefasse des menschlichen Riickenmarks. Lemberg, 1889.
(5) RUpDINGER, T:
Atlas der peripherischen Nervensystems der menschlichen Kérpers
Stuttgart, 1872.
(6) Litperritz, C:
Ueber das Riickenmarkssegment. Ein Beitrag zur Morphologie und
Histologie des Riickenmarks. Archi f. Anatomie u. Entwickelungs-
geschichte. Anat. Abtheil. Jahrgang, 1881. p. 423-495.
40 JOURNAL OF COMPARATIVE NEUROLOGY.
(7) RAVENEL, M:
Die Maasverhaltnisse der WirbelsAule und des Riickenmarkes beim
Menschen. Zeztschrift f. Anatomie u. Entwickelungsgeschichte. Bd. il.
1877. Pp. 334-356.
EXPLANATION OF CHART I.
This chart represents by curves, the areas of the cross-sections of several
human spinal cords, as well as the areas of the gray and white substance as
they appear in each section. The base line in all the charts is just one-third
the length of the spinal cord for which it stands, and is divided into lengths
proportional to those of the spinal cord segments of which it is composed. For
the adult cord, the lengths of the segments given in Table I were used in
making the original drawings. On the ordinates one linear millimeter corre-
sponds to one square millimeter of area. In all cases the measurement of the
area was made up at the caudal end of the segment. In the order from above
downwards, the curves are as follows:
Composite Curve—Bised on A, B, C, and D, to give the average of the
several areas in the curves named. The curves are generalized and apply toa
cord of medium length—441,6 cm. long. The influence of sex is neglected.
The average age of the four cases would be 33 years.
Curve A. Man of 45 years. Data for areas from STILLING.
Curve B. Woman of 35 years. Data for areas from STILLING.
Curve C. Woman of 25 years. Data for areas from STILLING.
Curve D. Man of 25 years. Data for areas from STILLING.
Curve E. Child—data for areas from STILLING’s observations on the
cord of the two-year old child. Length of segments from
LUDERITZ’s observations on the cord of a three and a half
year old girl. Cord rather short.
Curves showing area of cross section of human spinal cord.
Sse seo White) matter: ssnsconansensssereroneene(S rey matter.
100
look MMV VY VivIvinT Hot Wo vo vio va vit IX X
A. Mati 45 yrs.
20
100 Bb. Woman
x!
» Woman 2oyrs.
D. Man zoy rs.
CERVICAL THORACIC
TUIMWYVUWWIn © VW Vv WW VE KX XxX
XI (Xi
AUTO WY = VESTER “anv = = = = VM EX XX MM eee
CERVICAL THORACIC LUMBAR.SACRAL
Entire section.
Composite curves based on A. B.C and D.
Th WW WV TW VY!
LUMBAR
SACRAL
To face page 40,]
CHART I.
Xi.
NEUROLOGY. Volt.
JOURNAL OF COMPARATIVE
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THE BRAIN OF THE ‘ARCHZOCETI.’
By Gi EcLon Smite; MSA. M.D,
Fellow of St. John’s College, Cambridge; Professor of Anatomy, Egyptian
Government School of Medicine, Catro.
{A paper read before the Royal Society of London, February 12, 1903. ]
So far as I have been able to ascertain, nothing whatever
is known of the form of the brain or, more strictly, of the
cranial cavity in the Archzoceti. Hence no apology is
needed for presenting even this imperfect account of two
cranial casts representative of this sub-order, which have come
into my hands.
Among the Eocene remains found in the Fayim region of
the Egyptian desert by Mr. H. J. L. Beapneri and Dr.
CHARLES W. ANDREwS, in Igol, there was a broken skull of
Zeuglodon,* from which it was possible to obtain a mold, repre-
senting the form of the greater part of the dorsal and lateral
aspects of the brain. A plaster cast was made in the British
Museum at the instance of Dr. ANDREWws, who kindly placed it
at my disposal for description.
In the following winter (1902), Mr. BEADNELL found in
the same locality a natural cranial cast of the same size and
general form as the artificial cast of Zeuglodon. It is obvious
at a glance, if the two specimens be placed side by side, that
the natural mold belongs to some member of the Archzoceti,
1 These notes were originally intended for the Report on the Survey of the
Fayfim, to be issued by the Egyptian Survey Department, and are now pub-
lished separately with the permission of the Under Secretary of State for Public
Works and Captain H. G. Lyons, Director-General of the Survey Department.
2 C. W. ANDREWS, “‘Extinct Vertebrates from Egypt,” Part II. (Extracted
from the ‘Geological Magazine,’ N. S., Decade IV, vol. 8, I901, p. 437,—
Zeuglodon Osiris, Dames’.)
42 JOURNAL OF COMPARATIVE NEUROLOGY.
but whether to the same species or even genus as the other
specimen must at present remain an open question.
Mr. BEADNELL kindly placed this specimen at my disposal.
The size and relative proportions of the different parts are
almost identical in the two casts. Nevertheless, there are a
considerable number of differences, some features being dis-
played in one and not in the other, and wee versa. Many of
these differences are obviously due to the imperfections of the
casts, and especially to the failure of the plaster mold to repre-
sent the true form of the brain. But there are several peculli-
arities of the natural cast—such, for example, as the form of
the caudal part of the cerebellum and the shape of the cerebral
hemispheres—which are difficult to reconcile with the artificial
mold, even if we admit that the inner face of the cranium
(from which the latter was made) is damaged or imperfectly
cleaned. The differences, nevertheless, are sufficiently pro-
nounced to indicate a generic distinction between the two speci-
mens; and in this connection it is interesting to recall a state-
ment made by Dr. AnprReEws in his first reference to Zeuglodon,
as ‘including apparently Damers’ Z. Osiris, and perhaps a
second species.”’’ It would, however, be very unwise, because
it would serve no useful purpose, and possibly lead to error, to
found a new genus or even a new species on the evidence of
this natural cranial cast, when our source of information con-
cerning the known genus (Zeug/odon) is as unsatisfactory as that
obtainable from the artificial one about to be described. More
especially so, when it is remembered that in the case of the
only indisputable facts (z. e., size and general form) the two
casts are agreed. [shall therefore merely describe and attempt
to explain the meaning of the form of the two specimens, and
leave the question of the specific identity open for future re-
search.
The general appearance of the brain is extraordinarily
peculiar (figs. 1 and 2). The shape of the anterior part of the
natural cast (fig. 1, @ and 6) closely resembles the cerebrum of
1 ‘Geological Magazine,’ September, 1901, p. 401.
Exuiot Smitu, Sram of Archeocete. 43
a Lizard greatly magnified. An anterior prismatic stalk (a),
representing the pedunculi olfactorii, suddenly expands into a
plump, broad, smooth mass (4), showing the form of the chief
part of the cerebrum. The maximum breadth of the two hemi-
spheres (fig. 1, 4) is 95 mm.; the greatest length of each (mea-
Fic. 1.—Dorsal aspect of the natural cast described in the text. Two-ninths
natural size. a@, olfactory peduncles; 46, cerebral hemisphere; , @,
cerebellum ; ¢, é, fragments of skull.
sured in front from the point where the ventral surface of the .
olfactory peduncles appear to expand into the chief mass of
the hemisphere) is 47 mm.; and the maximum depth is 54
mm. Each cerebral hemisphere (exclusive of the olfactory
peduncle) is slightly broader than it is long.
The two olfactory peduncles are represented in the natural
cast by a single prismatic process. This extends forward for a
distance of 37 mm. (measured along the dorsal edge) in front
of the point where the expansion to form the hemispheres com-
44 JOURNAL OF COMPARATIVE NEUROLOGY.
mences; and, as the peduncles are broken across there, it is not
possible to estimate their total length or the shape and size of
the olfactory bulbs.
The coronal section formed by its anterior (broken) surface
gives an isosceles triangle with a base measuring 8:5 mm. and
sides of 10 mm. each. It expands as it passes backward, so
that at its junction with the rest of the hemisphere its sides are
each Ig mm. and its base 16 mm. in length.
Fic. 2.—Dorsal aspect of the artificial cranial cast of Zeuglodon. Two-ninths
natural size. a, 4,c,d,as in fig. 1. @, the dorsal rostrum, and 40’, an
irregular boss on the cerebral hemisphere. (These are probably due to
imperfections in the cranium.)
In the artificial cast (fig. 2) all that represents this exten-
sive olfactory stalk is an irregular rostrum with two small boss-
like projections, one above the other (a and a). The cerebral
hemispheres in the natural cast have a broad base, from which
Exuiot SmitH, Brain of Archeocett. 45
the sides extend upward toward the narrow dorsal surface with
a gradual slope. In the artificial cast, however, the lateral
parts of the hemispheres seem to be expanded into full rounded
swellings.
Then, again, the antero-posterior diameter of the hemi-
sphere is much shorter (being about 13 mm. less) than it is in
the natural cast, although the breadth of the two specimens. is
approximately the same. It may be that the anterior parts of
the skull, from which the artificial cast was made, are so dam-
aged that little reliance can be placed upon the mold as an in-
dication of the exact form of the brain. In fact, if this
artificial cast even approximates to the form of the brain, it is
quite certain that it did not belong to the same genus as the
animal from which the natural cast was derived.
In other words, as we know that the artificial cast belonged
to Zeuglodon, the probability is that the natural cast furnishes
the first evidence of some hitherto undescribed genus of
Archzoceti.
Behind the part 8, which I have just described as the
cerebrum, there is (in the natural cast) a large, irregular mass
of avery peculiar shape, not exactly comparable to the condi-
tion occurring in any other brain known to me.
Immediately behind the hemispheres (d) there is a great
transverse bar (c) measuring 125 mm. in the transverse direc-
tion—z.e., extending on each side 15 mm. beyond the lateral
margin of the cerebrum (6).
Each lateral extremity of this mass (c) is expanded to form
a large buttress. In the natural cast these buttress-like masses
are practically vertical, and of uniform thickness ; whereas in
the artificial cast they are obliquely-placed, and expanded ven-
trally. In the natural cast the mesial continuation of these
thick lateral masses (each of which measures 30 mm. antero-
posteriorly) becomes reduced to a bridge measuring only 5 or
6 mm. [the exact figure cannot be stated, because a piece of
bone (fig. 1, ¢) partially covers this region].
In the deep concavity behind the narrow bridge of the area
¢ (in the natural cast) two rounded, irregular, walnut-like bosses
46 JOURNAL OF COMPARATIVE NEUROLOGY.
project, one on each side of the middle line (fig. 1, d@). Each
of these is 26 mm. in diameter, and is placed so obliquely that
its surface looks almost directly backward. Shallow but clearly
defined furrows separate these two bodies from each other and
from the area c. In the artificial cast there is only a very
faintly-marked indication of these bodies (fig. 2, @).
Ata first glance it might seem that they represent the
whole cerebellum, in which case c would be part of the cere-
brum! But careful examination of the natural cast renders
such an interpretation highly improbable, and comparison with
the artificial cast seems to finally establish the belief that the
whole of the region marked c forms part of the cerebellum.
It is extraordinarly difficult to accurately interpret this pe-
culiar form of cerebellum. A comparison with other primitive
types of cerebellum’ points to the probability that the lateral
buttresses of the mass c represent the floccular lobes, and that
the walnut-like mass (@) represents the cerebellar lobule which
I have called ‘‘area C” (of. cet., ‘Catalogue,’ p. 201). 7ifieibe
objected that the lateral buttress-like mass is much too exten-
sive to be entirely ‘‘floccular,’’ attention may be called to the
fact that in the large aquatic Sirenia, which have retained an
exceedingly primitive type of brain, the floccular lobes are
enormous in comparison with those of other mammals (of. c7z.,
‘Catalogue,’ p. 346).
It would perhaps be difficult to find elsewhere in the mam-
malia a greater contrast than that presented by the smooth,
reptilian-like cerebral hemispheres of these casts and the highly
complicated, ultra-mammalian neopallium of the recent whales,
both Odontoceti and Mystacoceti.? And yet, if we inquire
into the nature of the factors which have molded the form and
determined the size of the various parts of the brain in Eocene
times and at the present, the contrast between the brain of
Zeuglodon and the modern Cetacea loses much of its signific-
1 Compare, for example (‘Catalogue of the Royal College of Surgeons,’ 2nd
edition, vol. 2, 1902), Armadillo (p. 211), Tapir (p. 311), Manatee (p. 346).
2 Vide ‘Catalogue of the Royal College of Surgeons,’ of. ctt., pp. 348—359.-
Evuiot SmitH, Brain of Archeocet. 47
ance, and becomes much less peculiar, even though it may not
be wholly explained.
In most Eocene mammals the cerebral hemispheres were
exceedingly diminutive in comparison with those of their mod-
ern descendants and successors. Moreover, the bulk of the
primitive mammalian hemisphere was composed of those parts
(hippocampus and lobus pyriformis), which are pre-eminently
olfactory ; in other words, the neopallium (z.e., that part of the
pallium which is neither hippocampus nor pyriform lobe) is
especially insignificant. It is a well-known fact that the sense
of smell loses much of its importance in mammals of aquatic
habits (e.g., Ornithorhynchus, the Sirenia, the Pinnipedia, and
especially the Cetacea), and in these animals the olfactory parts
of the brain dwindle to very small proportions. In the
Odontoceti the olfactory bulb and its peduncle actually disap-
pear. The Archeoceti, therefore, are subject to two factors,
which will account in some measure for their small cerebrum.
For, in addition to the smallness of the brain to which most
Eocene mammals are subject, there is their aquatic mode of
life. This causes a reduction in size of just those portions of
the pallium which form the greater part of the Eocene hemi-
spheres.
In the modern Cetacea the neopallium attains to the
greatest absolute size which it ever reaches in any mammal.
This fact cannot, however, be considered fatal to the belief in
the close affinity of the Archzoceti and the Cetacea, because
the extraordinary dissimilarity between the brains in the two
sub-orders is such as we know to have been produced by the
operation of well-recognised causes in the long lapse of time
which separates the dawn of the Tertiary period from the pres-
ent day. In all mammals which lead a life ‘‘in the open’’ it
has become a condition of their survival that the neopallium
must increase in size in each successive generation: failing this,
the creature must either adopt a ‘‘retired and safe mode of
life’’ or become extinct. Numerous examples might be
quoted in support of this hypothesis. But the case of the
Sirenia shows us how little we really know of the factors which
48 JoURNAL OF COMPARATIVE NEUROLOGY.
determine the size of the brain. These creatures began the
struggle for existence in Eocene times with relatively large
brains, in spite of their aquatic mode of life; and they have
been succeeded by generations ot descendants whose latest
progeny at the present day have a brain-equipment only
slightly superior to their earlier Tertiary ancestors (vzde Cata-
logue, of. cit. p. 344, ef seg.). Evenif we admit that the modern
Manatees and Dugongs lead an eminently safe and retired life,
which is in marked contrast to the venturesome and ‘‘open’’ life
of the whales and porpoises, much still remains to be satisfac-
torily explained.
Perhaps the most striking feature of the brain of Zeuglodon
is the extreme disproportion between the size of the enormous
cerebellum and the diminutive cerebrum. In this respect the
fossil brain presents a most marked contrast to that of all recent
mammals, and especially to that of the Cetacea. This relatively
great size of the cerebellum is not peculiar to the Archzoceti,
but is common to other extinct mammals of large size. In my
memoir on the brain in the Edentata’ the difficulty presented
itself of adequately explaining a similar phenomenon in Glypto-
don; and it must be born in mind, in even attempting to do
this, (1) that the obtrusive greatness of the cerebellum presents
itself only in large mammals and not in lowlier vertebrates, and
(2) that the size of the cerebellum is not proportionate to that
of the cerebrum. In the case of Glyptodon I four years ago at-
tempted to explain these facts in this manner.
The development of the neopallium in mammals opens up
the possibility of the performance of many more complex mus-
cular acts than are possible in the Amphibia or Reptilia; these
acts require a co-ordinating mechanism, the size of which will
be largely determined by the bulk of the muscular masses, the
actions of which are to be harmonised, and the extent of the
sensory surfaces which send into the cerebellum streams of con-
trolling impulses. A large cerebellum is being demanded by a
1 «The Brain in the Edentata,’’ ‘Linnean Society’s Trans.,’ 2nd series,
Zoology, vol. 7, part 7, 1899, p. 381.
Exxiior Smitu, Lran of Archeocet.. 49
large mammalian body, even if the cerebrum is small. I cannot
offer any more satisfactory explanation of the magnitude of the
cerebellum in Zeuglodon than this,
It is clear from the foregoing that the extraordinarily great
contrast in the appearance of the brain of the Archzoceti and
that of the Cetacea cannot be urged as a reason against their
kinship, when it is remembered that the operation of known
factors is quite sufficient to explain the transformation of the
one type into the other in the time which has separated the
Eocene period from the present.
Having disposed of these negative arguments, we may
consider the positive evidence for Cetacean affinity in the brain
of Zeuglodon.
The shape of the cerebrum, and especially its relatively
great breadth, is peculiar. In fact, this form of hemisphere
rarely or never occurs among mammals, other than the Cetacea.
I have elsewhere’ attempted to explain the shortness of the
Cetacean hemispheres by the fact that the abortion of the basal
(olfactory) parts of the cerebrum limits their longitudinal ex-
tension. This, however, is not the whole explanation, because
in many microsmatic Sirenia (Za/icore), and Pinnipedia (Osaria,
Phoca), the hemispheres are not especially broad. The dispro-
portionate breadth seems, in fact, to be to some extent a char-
acteristic cf the Cetacea; and, in this respect, Zeuglodon agrees
with them.
The peculiar elongation of the olfactory peduncles be-
yond the anterior extremities of the hemispheres is rarely found
in mammals, though it is common enough in Reptiles and the
Ichthyopsida. In fact, the exact parallel to the condition found
in Zeuglodon occurs among recent mammals only in the Cetacea.*
An analogous condition is found in the extinct Lemuroid
Megaladapis [described by ForsytH Major (of. cét.)] and some
Amblyopoda.
1 ‘Catalogue of the College of Surgeons,’ of. czt., p. 350.
* Full references to this are given by ForsyrH Major, ‘‘On the Brains of
Two Sub-Fossil Malagasy Lemuroids,” ‘Roy. Soc. Proc.’ vol. 62, 1897, p. 48,
second footnote.
50 JouURNAL OF COMPARATIVE NEUROLOGY.
It is not without interest to note that the two outstanding
features of the cerebral hemispheres of the Archzoceti, even if
their value as indices of kinship be slight, both find their near-
est parallel in Cetacea. There are no characters of the brain
of the modern Cetacea which can be regarded as certainly dis-
tinctive, if we put aside such features as the extreme dwindling
of the olfactory apparatus, and the enormous development of
the neopallium. Both must be regarded as late acquisitions,
not to be expected in an Eocene mammal. Under these cir-
cumstances these slight points of positive evidence of the rela-
tionship of the Archeoceti and Cetacea must be allowed some
value, as reinforcing the testimony of the skeletal parts.
If we seek to institute closer comparisons between the
brain of Zeuglodon and of the Odontoceti and Mystacoceti with
a view to the determination of its relationships, we are not un-
naturally doomed to disappointment. It might, perhaps, be
supposed by some anatomists that the absence of an olfactory
bulb in the Odontoceti might point to a closer affinity of
Zeuglodon to the Mystacoceti, in which a small olfactory appa-
ratus is retained. But there is every indication that the ol-
factory apparatus of the Odontoceti has become aborted quite
recently.
Fic. 3.—Ventral aspect of brain of an early feetus of Monedon. Naiural size.
a. d., locus perforatus (area desert); 4.0., bulbus olfactorius; /.., lobus
pyriformis.
Thus in a specimen of the embryonic brain of the Narwhal
(Monodon), which was given to me some years ago by Professor
Howes, the remains of the olfactory bulb (fig. 3, 4.0.) are still
Exviot SmituH, Braz of Archeocett. 51
quite visible as a small umbilicate area in part of the ‘‘ desert
of Broca (fig 3, a.d.), wherefore it follows that in the
early embryo the olfactory bulb and peduncle develop as in all
”
region
other mammals. Moreover, in all Odontoceti traces of the py-
riform lobe are found even in the adult; and in the brain of
Kogia greyt the rhinal fissure and the typical (macroscopically
only) pyriform lobe are retained in a form as clearly defined as
that of any macrosmatic mammal (fig. 4). Professor HASWELL,
in describing this brain’ emphasises the fact that ‘‘the most re-
Fic. 4.—Ventral aspect of left hemisphere of Cogza greyt. Reduced approxi-
mately one-half. a.d., corpus striatum (area desert); 4.0., place occupied by
bulbus olfactorius in feetus; /.7.@., fissura rhinalis anterior; /.7.2., fissura
rhinalis posterior; /7.4., lobus pyriformis.
markable feature of the [basal] region, and perhaps of the
whole brain, is in the great depth of the ectorhinal fissure, a
feature marking off the present form very strongly from
Delphinus”’ (p. 438). Since his illustrations do not properly
delineate this interesting conformation, Professor HAswELi
1 W. A. HASWELL, ‘‘On the Brain of Grey’s Whale (ogia greyz),” ‘Lin-
nean Society of New South Wales Proc.,’ vol. 8, 1883 (publ. 1884), pp. 437-439,
pl. XXI.
52 JOURNAL OF COMPARATIVE NEUROLOGY.
kindly permitted me to examine his specimen; and Mr. J. P.
Hirt has made me an excellent photograph (of its ventral sur-
face), roughly reproduced the accompanying drawing (fig. 4).
It shows the complete and quite-typical rhinal fissure and the
characteristic pyriform lobe. In its anterior part the rhinal
fissure is fully a centimeter deep.
The exact reproduction of these characters of the rhinence-
phalon in an adult anosmatic Cetacean, and the presence of the
olfactory bulb in the foetal Narwhal, show that these toothed
Cetaceans were certainly (and probably quite recently) derived
from ancestors presenting the normal mammalian type of olfac-
tory apparatus. The absence of the olfactory bulb and pedun-
cle in the Odontoceti cannot, therefore, be considered a just
reason for adopting the utterly improbable suggestion of a nearer
affinity of the Archzoceti to the Mystacoceti than to the
Odontoceti.
Estimated by the amount of sand which it displaced, the
bulk of the natural cast (including that of a considerable
quantity of matrix attached to the base of the brain and some
small fragments of bone) is 410 c.c. If the necessary correc-
tions and estimations be made from this gross cubic capacity,
the weight of the brain in the Archzoceti must have been con-
siderably less than 400 grammes, and perhaps nearer 300, as
against that of the recent Cetacea, which ranges from 455
grammes in Kogza (HASWELL) to 4,700 grammes in Balwnoptera
(GULDBERG).
LITERARY NOTICES.
Functional Changes in the Dendrites of Cortical Neurones.'
This paper is largely a reprint of a work published in 1897 in the
first volume of the Travaux de l'Institut Solvay, whose results the
author now regards as fully confirmed and established. Some of these
conclusions are as follows:
The pyriform appendages (spines or thorns) of the dendrites of
the cortical neurones constitute the terminal apparatus of the dendrites;
they increase considerably the surfaces of the nerve cells and play an
important rdle in the physiology of the brain, for in the case of severe
disturbance the appendages disappear partially or wholly from the
affected cells.
Varicosities represent in the adult brain pathological modifications
of the nerve cell. They appear abundantly only in course of grave
disorders and are rare in the brain of the healthy animal. In the
normal adult the dendrites of cortical neurones do not show varicosi-
ties, but are thickly set with the pyriform appendages.
In prolonged etherization, or electrical stimulation or fatigue of
the cortex the pyriform appendages disappear, while varicosities are
present, but these two phenomena are really independent of each
other and the appendages may disappear without any trace of vari-
cosities making its appearance. The author concludes from the disap-
pearance of the appendages that these are motile, but is unable to
determine the mechanism of their movement. The cortex is never
uniformly involved in the reactions to fatigue, etherization, etc., but
beside the affected areas are others apparently unaffected. The paper
is followed by a list of 14 titles of papers by the same author on related
subjects. Chyna.
1 STEFANOWSKA, MICHELINE. Les Appendices des Terminaux Dendrites
Cérébraux et leurs différents états physiologiques. Archives des Sciences
Physiques et Naturelles, Quatriéme période, t. XI, May, rgor,
ii JouRNAL OF ComPARATIVE NEUROLOGY.
The Morphological Position of the Chorda Tympani in Reptiles.
It is generally agreed that the Eustachean tube and tympanic
cavity of the higher vertebrates are morphological derivatives of the
spiracular cleft of the lower fishes. If the chorda tympani of human
anatomy runs down cephalad of the tympanic cavity, as commonly
taught, then the precursor of this nerve in the fishes, if such there be,
should be pre-spiracular. ALLis } has lately called in question the pre-
spiracular (pre-tympanic) character of the mammalian chorda and of
course the homologous nerve cannot be sought in the fishes until this point
is determined. Since the mammalian chorda pursues an exceedingly
tortuous course and one difficult of interpretation, it is worth while to
notice the conditions in the reptiles.
VERSLUYS in his recent extensive paper ? describes and figures
these relations in several types of Lacertilia and Rhynchocephalia and
comes to this general conclusion: ‘‘ Die chorda tympani geht vom
Facialis meist an der Stelle ab, wo dieser sich mit dem eben beschrie-
benen sympathischen Nerven verbindet, das ist caudal von der Columella
und an der inneren dorsalen Ecke des Kérpers des Quadratums. Sie
reicht dann langs der dorsalen und vorden Baukenhéhlenwand auf der
medialen Flache des in die Paukenhdhle vorspringenden Quadratkér-
pers bis zum Unterkiefer.” The detailed descriptions and figures
make it very plain that the chorda tympani of reptiles is pre-tympanic
and therefore morphologically pre-spiracular; and in the absence of
very definite proof to the contrary, we must assume the same condi-
tion to prevail among the mammals also. C. Si 0aH.
Mendel and Jacobsohn’s Jahresbericht; Fifth Issue.*
The issue of this Annual for 1901 reaches us early in 1903 and, like
its predecessors, is an indispensable aid to all research workers in all
departments of neurology and psychiatry. The plan of the work is
the same as in previous issues.
1 ALLIs, E. P. The Lateral Sensory Canals, the Eye-muscles and the
peripheral Distribution of certain of the Cranial Nerves of Mustelus laevis.
Quart. Journ. Micro, Sct., XLV. 2, 1901.
2 VerRsSLuys, J. Die mittlere und Aussere Ohrsphare der Lacertilia und
Rhynchocephalia. Zool. Jahr., Abt. f. Amat., XII, 1899.
3 Jahresbericht tiber die Leistungen und Fortschritte auf dem Gebiete der
Neurologie and Psychiatrie. V. Jahrgang. Bericht iiber das Jahr 1gor.
Berlin, S. Karger, 1902.
ee
_e
—e
Literary Notices.
Nervous System of Myxine.'
Dr. Holm used a variety of staining methods upon strictly fresh
material and is therefore in a position to add many details of import-
ance to our knowledge of this critical form. His most serviceable
preparations are those stained by the method of Gote1 and by the
iron-haematoxyglin of HaIpENHAIN. The histology of the entire brain
is considered; but the results, it must be confessed, are disappointing.
While the paper contains much of value and is carefully wrought out
and clearly arranged, yet the author has apparently failed to make
the most of his material. The discussion of the medulla oblongata,
comprising about half of the paper, is especially weak, due largely, it
would seem, to the neglect of important recent literature, especially
that coming from England and America. oA Ab
Taste and the Fifth Nerve.?
The study of five consecutive cases of total removal of the Gas-
serian ganglion by Krause’s operation shows that several weeks after
the operation there is a total loss of taste on both the tip and the back
of the tongue on the operated side. The author concludes that all the
fibers of taste reach the brain by the root of the fifth nerve and that
none of these fibers reach the brain by either the seventh or the ninth
roots. roy Ines
The Phylogeny of the Pallium.’®
This volume, for which we are indebted to the kindness of Pro-
fessor G. Eliot Smith, contains descriptions of the nervous system of
the Invertebrata and of the brain and spinal cord of the Vertebrata of
the collections of the Royal College of Surgeons. The Invertebrata,
spinal cords of Vertebrata and brains of Fishes, Amphibia and Birds are
described by Mr. R. H. Burne; the brains of the Reptilia and Mam-
malia by Professor G. Elliot Smith, assisted in the Primates by Mr.
W. L. H. Duckworth.
1 HoLM, JOHN F. The Finer Anatomy of the Nervous System of Myxine
glutinosa. Gegenbaur’s Morph. Jahrb., XXIX, 3, 1901, pp. 365-401.
2 Gowers, W. R. Taste and the Fifth Nerve. Journ. of Physiol. XXVIII,
4, July, 1902.
8 Descriptive and Illustrated Catalogue of the Physiological Series of
Comparative Anatomy contained in the Museum of the Royal College of Sur-
geons of England. Second Edition. Vol. II. Zondow: Taylor and Francis,
1902, pp. x, 518.
iv JouRNAL oF CoMPARATIVE NEUROLOGY.
The volume, we should say, is very nearly an ideally perfect cata-
logue. With its lucid descriptions and exceptionally clear wood cuts
it is of great value as a work of reference even to those who do not
have access to the specimens which it describes.
At the end of the descriptions of the brains is a summary which
we venture to quote in full.
The human brain is by no means the largest known to us. The
Elephant and the Great Whales possess much larger organs, and even
the extinct Sirenian AAytina was provided with a brain of larger abso-
lute dimensions than that of Man. In the case of these huge animals
the enormous mass of the brain is probably to be explained by the fact
that the increase in size of the surface of the body necessitates a
corresponding growth of the neopallium (to which the great proportions
are chiefly due), which is the ultimate receptive-organ for sensory im-
pressions.
In the case of the human brain, however, the Anthropoid Apes
(which approach near to Man in bodily dimensions) afford us a criterion
as to the amount of neopallium which may be regarded as ‘‘necessary”
(in the Family Simiidz) for the reception of impressions coming from
such an extent of sensory surface as Man possesses. When it is re-
membered that the largest Ape’s brain is approximately half the size of
the smallest normal human brain, and the average Gorilla’s brain only
about one third (approximately) the weight of the average European’s
brain, it will then be understood how great an area of neopallium (to
which the disproportionate size of the human and Anthropoid brains
is chiefly due) Man possesses over and above the needs of the average
member of the Simiidz, to serve as the physical basis (so to speak) of
an associative memory of immeasurably greater potentialities (for stor-
ing and comparing sensory impressions) than that of any other animal.
The feature, therefore, which distinguishes the human from all other
brains is the relatively enormous size of the neopallium in comparison
with the minimum which the forces of natural selection have made a
condition of survival in a member of the Simiidee. *
The neopallium assumes important functions and becomes a condi-
tion of survival for the first time in the Mammalia, and in each succes-
sive epoch it has become incumbent upon every mammal either, on the
one hand, to adopt some eminently safe mode of life or some special
protective apparatus to avoid extinction, or, on the other hand, to
“cultivate” a larger neopallium, which, as the organ of associative
memory, would enable it to acquire the cunning and skill to evade dan-
ger and yet adequately attend to its needs. In many of the Eocene
Mammalia (cf. the cranial cast of Dénoceras) the neopallium is reduced
1 IT use the term ‘‘neopallium’”’ (Journ. Anat. and Phys. vol. xxxv, 1901, p.
431) because the other parts of the pallium, #. ¢. the hippocampus and pyriform
lobe, do not share in thisincrease. [The significance of the term ‘‘neopallium’’
is explained in the article here cited. Cf. also the abstract in this JOURNAL,
vol. XII, p. xii.—c. J. H.]
Literary Notices. Vv
to such diminutive proportions that the brain resembles the reptilian
type; and in each successive generation the neopallium becomes larger
or the creature, in self-defence, is compelled to adopt some safe form
of life. The Aippopotamus and the Sirenia are examples of mammals
which have not kept pace in the fierce race for neopallial supremacy
but survive by adopting habits of life which are eminently safe. The
condition of the human brain represents the other extreme. Here the
neopallium has attained its maximum development, and its possessor
has not had to seek refuge either in a retired mode of life or by any
protective specialisations of structure either for offence or defence, but
has attained the dominant position in the animal kingdom, whilst re-
taining much of the generalised structural features of a primitive mam-
mal.
This expansion of the neopallium is general and not restricted to
any localised areas. Thus we cannot say that the greatness of the hu-
man neopallium is to be wholly attributed to a growth of the frontal or
of the parietal or of the occipital areas, as various writers have main-
tained; because all parts exhibit distinct evidences of extension. But
some regions exhibit the effects of this general expansion more de-
cisively than others, and many writers have assumed (quite erroneously,
I believe) that such effects are to be attributed to localised growth. !
Thus there are very noteworthy evidences of growth in the region
around the insula in the human brain, but this is probably for the most
part an expression of the general extension in a region which lends
itself to a clear demonstration of any increase.
In the early mammals the olfactory areas form by far the greater
part of the cerebral hemisphere, which is not surprising when it is re-
called that the forebrain is in the primitive brain essentially an append-
age, so to speak, of the smell-apparatus. When the cerebral hemi-
sphere comes to occupy such a dominant position in the brain it is per-
haps not unnatural to find that the sense of smell is the most influential
and the chief source of information to the animal; or perhaps it would
be more accurate to say that the olfactory sense, which conveys general
information to the animal such as no other sense can bring concerning
its prey (whether near or far, hidden or exposed), is much the most
serviceable of all the avenues of information to the lowly mammal lead-
ing a terrestial life and therefore becomes predominant; and its par-
ticular domain—the forebrain—becomes the ruling portion of the
nervous system.
This early predominance of the sense of smell persists in most
mammals (unless an aquatic mode of life interferes and deposes it:
compare the Cetacea, Sirenia, and Pinnipedia for example) even though
a large neopallium develops to receive visual, auditory, tactile, and
other impressions pouring into the forebrain. In the Anthropoidea
alone of non-aquatic mammals the olfactory regions undergo an absolute
1 There is no doubt that localised hypertrophies do occur, but the funda-
mental distinction of the human brain is the gemera/ expansion of the whole
neopallium.
vi JouRNAL OF COMPARATIVE NEUROLOGY.
(and not only relative, as in the Carnivora and Ungulata) dwindling,
which is equally shared by the human brain, in common with those of
the other Simiide, the Cercopithecidz, and the Cebide. But all the
parts of the rhinencephalon, which are so distinct in macrosmatic mam-
mals, can also be recognised in the human brain. The small ellipsoidal
olfactory bulb is moored, so to speak, on the cribriform plate of the
ethmoid bone by the olfactory nerves so that, as the place of attach-
ment of the olfactory peduncle to the expanding cerebral hemisphere
becomes removed (as a result of the forward extension of the hemi-
sphere) progressively farther and farther backward, the peduncle be-
comes greatly stretched and elongated. And as this stretching involves
the grey matter without lessening the number of nerve-fibers in the
olfactory tract, the peduncle becomes practically what it is usually
called, z. e. the olfactory ‘‘tract.” The tuberculum olfactorium becomes
greatly reduced and at the same time flattened, so that it is not easy to
draw a line of demarcation between it and the anterior perforated
space. The anterior rhinal fissure, which is present in the early
human foetus vanishes (almost, if not altogether) in the adult. Part of
the posterior rhinal fissure is always present in the ‘‘incisura tempor-
alis,”’ and sometimes (D. 710), especially in some of the non-European
races, the whole of the posterior rhinal fissure is retained in that typi-
cal form which we find in the Anthropoid Apes. When this occurs we
can easily recognise the caudal limits of the pyriform lobe, which other-
wise becomes confused with the neopallium.
The hippocampal fissure is of a peculiarly consistent nature, and is
found in all mammalian brains from Orasthorhynchus to Homo. The
rhinal fissure is equally sus generis and almost as constant as the hippo-
campal. .41 IP p: 297.
ON THE PHYLOGENY AND MORPHOLOGICAL POSI-
DIONIOE THE TERMINAL BUDS OF FISHES:*
By C. Jupson Herrick.
These curious sense organs occurring in the skin of certain
fishes have been a source of perplexity and controversy among
morphologists since their discovery by Leypic in 1851. They
are found freely scattered over the surface of the skin of the
head and trunk in certain teleostean and ganoidean fishes, par-
ticularly in exposed situations, and hence by many observers
have been regarded as tactile organs. Indeed, MERKEL in
1880, having failed altogether to find the proper tactile nerves
in the skin of fishes belonging to what we now designate as the
general cutaneous system, supposed that these organs, together
with the neuromasts or organs of the lateral line system, were
developed in compensation for the absence of the typical free
tactile nerve endings of the other vertebrates. This we now
know to be wide of the mark, for all fishes which possess either or
both of the systems of special sense organs mentioned above
also possess in the same cutaneous areas an abundant general
cutaneous nerve supply for tactile sensation.
We must distinguish at the outset three distinct types of
sensory nerve endings in the skin of fishes and then inquire in-
to their respective morphological rank; viz., (1) the general
cutaneous nerve termini, (2) the neuromasts, or organs of the
acustico-lateralis system of sense organs, (3) the terminal buds,
or end-buds.
(1) The first type comprises the ordinary tactile nerves,
making up the greater part of the spinal dorsal roots, but rep-
resented in certain ones only of the cranial nerves. They are
1 Studies from the Neurological Laboratory of Denison University, No.
XVII.
122 JOURNAL OF COMPARATIVE NEUROLOGY.
free nerve endings in the skin without specialized sense organs
and may be regarded as in all probability the most primitive
type of sensory ending.
(2) Neuromasts. This system of sense organs includes
_the lateral canal organs, pit organs, ampullae and all other
specialized organs associated with the lateral line canals and in-
nervated by lateralis nerves, together with the sense organs of
the internal ear of like phylogenetic origin and innervation.
These organs clearly belong to asingle system and the evidence
thus far accummulated favors the inference that the system asa
whole has been derived phylogenetically from the general cuta-
neous system of nerves. This is not the place to give the de-
tailed proof of this, but the trend of the current argument may
be summarized as follows under two heads:
(a) the sense organs themselves are characterized in their
adult and highly functional condition by the presence of hair
cells differentiated from indifferent supporting cells and extend-
ing only part way through the epithelium of the sense organ.
These hair cells may not occur in the earliest embryological
stages of development of the organs, nor in states of functional
and structural degradation. The former point accounts for
the statements of several authors to the effect that the lateral
line organs pass through a developmental stage which is similar
to the adult structure of the terminal buds, and the latter point
for the confusion which has arisen in the minds of many
authors, giving rise to the belief that there is no clearly marked
structural difference between neuromasts of the lateral line
series and the terminal buds. Nevertheless, the distinction
drawn by ScuuLzE and MerKEL between the neuromasts and
terminal buds, the former possessing the hair cells and the
latter not, stands as an essential criterion in all cases where the
organs are well developed. Now these hair cells resemble
somewhat in structure and probably also in mode of function
the tactile hairs of certain aquatic invertebrates and in fact are
probably phylogetically derived from them. ParKER (’03) has
shown clearly the probable line of differentiation of these
structures from tactile organs for the perception of mass move-
Herrick, Zevminal Buds of Fishes. » 123
ment of the water to organs of equilibration and hearing. We
therefore have structural and physiological evidence that the
sense organs of the acustico-lateralis system have been derived
from tactile organs.
(b) Now turning to the central connections of the acustico-
lateralis nerves within the brain, we have a quite independent
line of evidence. It has long been known that these nerves all
end in the tuberculum acusticum and associated centers, and it
has recently been shown, particularly by JOHNSTON in an im-
portant series of papers, that these centers are all derivatives of
the general cutaneous or tactile centers of the brain. While
my own studies on the teleosts have shown that in these higher
fishes the specialization of the acustico-lateralis centers has
progressed so far as to obscure the primary relations, JoHN-
STON’s observations on the lower fishes leave no room for doubt
that the history is as stated above.
From the concurrent history of both central and peripheral
relations we are therefore justified in assuming that the neuro-
masts and their associated nervous apparatus have been de-
rived from the general cutaneous or tactile system of nerves.
(3) The terminal buds (end-buds, beaker organs, etc.) are
by no means on 30 secure a morphological foundation. It is,
however, now definitely known that they resemble in every es-
sential respect the taste buds within the mouth cavity. The
specific sensory cells are not hair cells, but, like the indifferent
supporting cells, they run through the entire thickness of the
sensory epithelium from external to internal limiting membrane.
They may terminate distally in a short stiff bristle, but never in
the tuft of long hairs characteristic of hair cells. The organs
usually rest on a raised papilla of dermis, and finally in every
case where the innervation is accurately known they are sup-
plied by communis nerves, which have nothing in common
either centrally or peripherally with the general cutaneous or
acustico-lateralis systems of nerves. On the other hand, these
nerves always terminate within the brain in a single center
(bilobed in some fishes), the vagal lobe (plus facial lobe in silur-
124 JOURNAL OF COMPARATIVE NEUROLOGY.
oids and cyprinoids), which also receives the typical gustatory
fibers from the taste buds of the mouth.
If now it can be shown that the terminal buds differ func-
tionally, as well as in this thorough-going structural fashion,
from all other cutaneous sense organs, then it would appear
that their rank as a separate system of sense organs should re-
main unchallenged. And _ such in fact is the attitude of most
of the recent students of this question, even without a rigid de-
monstration of the functional relations. I am, however, at this
time in a position to contribute positive facts regarding the
functions of the terminal buds, and since one recent author of
note has within the year made a very forcible plea for a return
to the older standpoint of Leypie and others that terminal buds
and neuromasts are genetically related, I am moved to review
the whole question again.
But first we must examine more thoroughly the central
nervous connections of the terminal buds, since the morphologi-
cal argument really hinges upon this point. I repeat, that the
terminal buds of the outer skin of fishes are known to be inner-
vated by a-system of nerves which is enterely distinct throughout
from either the tactile or lateralis nerves. There are no accu-
rate observations which contradict this conclusion, while the
positive evidence is quite decisive. The most convincing chap-
ter in the elucidation of this problem is, I think, my own exam-
ination of the innervation of the cutaneous organs in Ameiurus
(Herrick, 01), which was undertaken primarily to test this very
question. The cyprinoids would give an equally decisive an-
swer to the problem, as I know from personal observation (as
yet unpublished), though perhaps here the evidence would not
be quite so easy to read. |
The nerves from these terminal buds, no matter where
they are located on the body, always reach the central nervous
system through cither the X, LX or VII pairs of cranial nerves,
and so far as my personal observation goes, practically all come
in by the VII nerve, though all three of these nerves in all
types receive gustatory fibers from taste buds within the mouth.
Both of these classes of fibers, together with a large number of
Herrick, Zerminal Buds of Fishes. 125
unspecialized visceral sensory fibers must be treated together
within the brain, since they are so intimately intermingled that
analysis has so far proven impossible. Accordingly, they are
termed collectively the ‘‘communis system”’ of cranial nerve
fibers. Peripherally this system is clearly divisible into two
components, (1) the unspecialized visceral sensory which is
doubtless much more ancient phylogenetically, and (2) the
specialized, which for reasons to appear we may now term the
gustatory component. This component may be divided topo-
graphically into two divisions, one for taste buds within the
mouth, and one for terminal buds in the outer skin. It is the
latter division only, of course, with which we are here con-
cerned.
In fishes in which the terminal buds are not exceedingly
numerous, as in the cod, their nerve fibers, though they enter
the brain by the facial nerve, all turn back in the fasciculus
communis to find their terminal nucleus in the vagal lobe, along
with all other communis nerves of the body. But in the two
groups of teleostean fishes in which these organs are most
abundant (viz., the siluroids and cyprinoids) their nerve fibers
find their terminal nucleus at the cephalic end of the fasc. com-
munis in a special center, the lobus facialis. In both of these
groups. all of the terminal buds are innervated from the genicu-
late ganglion of the facialis root. Of this I am confident in the
siluroids (HERRICK, ’o1). As to the cyprinoids, a rather
cursory examination of sections of Carassius convinces me that
the same is true, though my study of this type is not by any
means exhaustive.
The facial lobe of the siluroids was formerly known as the
lobus trigemini, that of the cyprinoids as the lobus impar, in
the former case the structure being paired, in the latter un-
paired by the fusion in the dorso-median line of the lobes of
the two sides. That the facial lobes in these two groups of
fishes are really merely differentiated parts of the vagal lobes is
manifest, not only from the nature of their peripheral connec-
tions as indicated above, but still more evidently from their. in-
ternal structure and secondary fiber connections. I can speak
126 JOURNAL OF COMPARATIVE NEUROLOGY.
with confidence on the latter point, because I have now in an
advanced state of preparation a study of their connections and
internal organization based on an extensive series of sections by
several standard histological methods, including the methods of
WEIGERT and GOLGI.
It will not be necessary for me at this time to report these
histological observations further than to say that they abund-
antly confirm the conclusions to which JonnsTon was led in his
studies of Acipenser (’01) and Petromyzon (’o2), that the
primary and secondary connections of the communis system
within the brain are absolutely distinct throughout from those
of either the general cutaneous or the acustico-lateralis systems.
This I regard as a matter of the highest importance to any es-
timate of the morphological interpretation of the sense organs
innervated from these various centers
We may now turn to the consideration of the function of
the terminal buds. This is a matter to which I have devoted
considerable attention during the past year and with results
which I think may be regarded as decisively answering the
question. A preliminary account of these experiments was
presented to the American Association for the Advancement of
Science at the Pittsburg meeting (Abstract appearing in Sczence,
HERRICK, ’02) and the final report upon the problem is,now in
press in the Bulletin of the U. S. Fish Commission at Wash-
ington. From that report I excerpt the following summary of
results.
The entire cutaneous surface of Ameiurus is known to be
supplied with terminal buds, and particularly the barblets. In
the gadoid fishes terminal buds are known to be present on the
barblet and on the free filiform rays of the pelvic and dorsal
fins. Accordingly I chose as the chief subjects of investigation
Ameiurus nebulosus, the common ‘horned pout,’ Microgadus
tomcod, the ‘tom cod,’ and Urophycis tenuis, the ‘hake,’ to-
gether with a number of fishes such as Prionotus and Opsanus
in which microscopical examination has shown that terminal
buds are absent from the outer skin (MorriLi, ’95 and
CLAPP, ’99).
i Di
Herrick, Zerminal Buds of Fishes. 127
I may say at once that the fishes known to lack terminal
buds and the corresponding cutaneous branches of the commu-
nis system of nerves in all cases failed to give any response to
any kind of gustatory stimulus applied to the outer skin, in
marked contrast to the other types experimented upon.
The methods of experimentation upon the siluroid and
gadoid fishes in all cases were exceedingly simple, the attempt
being to approach as nearly to the normal feeding habits of the
species in question as possible. In particular, care was taken
to select only such gustatory stimuli as the fishes were already
familiar with and for which there were ready formed well de-
fined reflex paths.
The type of reaction to gustatory stimulation of the ter-
minal buds was found to be practically constant whether the
organs stimulated were situated on the dorsal fin (Urophycis),
on the ventral fin (Urophycis and Microgadus), on the barblets
(Microgadus and Ameiurus) or on the general body surface
(Ameiurus). The participation of visual sensations in the reflex
act evoked by the stimulus was excluded in certain of the cases
by the conditions of the experiment; e. g. in Ameiurus the
stimulus could be presented to the terminal buds of the body
or a barblet when the head was concealed under leaves or
debris on the bottom of the tank. I did not think it necessary
to blind any of my fishes because the experiments were suffh-
ciently clear without it, and besides BATESON (’90) has already
tried that experiment on certain European gadoid fishes, show-
ing that the reactions now under consideration are not affected
by that operation. The participation of the sense of smell was
excluded in the case of the tom cod by the destruction of the
olfactory organ, with no noticeable resultant modification in the
reflexes in question.
The problem is then narrowed down to the differentiation
between the senses of taste and touch in my experiments, and
this I think can easily be accomplished. My most common
mode of procedure was to touch the parts of the body where
terminal buds are known to be abundant with sapid substances
such as bits of meat, clam, etc., on the end of along slender _
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128 JOURNAL OF COMPARATIVE NEUROLOGY.
wire, when possible so arranging the experiment that the fish
could not see the point of contact. The fish immediately
turned witha characteristic movementand snapped up the morsel.
But the areas in question, particularly the barblets and free fili-
form fin rays, are known to be very richly supplied with gen-
eral cutaneous nerves in addition to the communis nerves for
the terminal buds; in other words they have a very rich tactile
innervation and doubtless are very sensitive to touch. Was
the reaction then essentially tactile or gustatory or both? To
test this point I replaced on the end of the wire the customary
bit of meat with a wisp of cotton wool or a piece of colorless
and tasteless gelatin which had been previously softened
up in cold water. The fishes sometimes would take it at
the first contact, though they would rarely repeat it and
soon ceased to notice the cotton or gelatin at all. If now the
cotton were soaked in meat juice and the contact repeated, the
fish always instantly reacted exactly as he did to meat in the
first instance and no amount of training would suffice to cause
him to discontinue the reaction to the cotton when dipped in
filtered meat juice.
In brief, the experiments which were hundreds of times
repeated in a great variety of forms, show that the fishes nor-
mally react to both tactile and gustatory stimuli upon the parts
of the body in question ; but by training they can be induced to
discriminate between the two classes of stimuli, ignoring the
simple tactile stimulus, but reacting to this plus the gustatory.
I varied the experiment, among other ways, by the use of a
fine-pointed pipette, directing a jet of water against the fish
and then similarly applying a jet of filtered meat juice. In'the
former case the jet was ignored or avoided; in the latter it was
always eagerly sought, the reaction being similar to that pro-
duced by a contact with meat, though more pronounced.
It may be regarded as established that fishes which possess
terminal buds in the outer skin taste by means of these organs
and habitually find their food by their means, while fishes
which lack these organs in the skin have the sense of taste con-
fined to the mouth. The delicacy of the sense of taste in the
—d
— a
Herrick, Zerminal Buds of Fishes. 129
skin is directly proportional to the number of terminal buds in
the areas in question.
Numerous unrelated types of bony fishes from the siluroids
to the gadoids which possess terminai buds have developed
specially modified organs to carry the buds and increase their
efficiency. These organs may take the form of barblets or of
free filiform fin rays. The free rays of the pelvic and dorsal
fins of gadoid fishes are thus explained, and indeed this is pos-
sibly the motive for the migration into the jugular position of
the pelvic fins of the gadoids. In all cases where terminal
buds are found on barblets or filiform fin rays gustatory nerves
belonging to the communis system are distributed to them.
The fishes in which the cutaneous terminal buds are most
highly developed are in general bottom feeders of rather slug-
gish habit and in some cases they are nocturnal feeders. The
high development of this sense is compensated for in some fishes
by the reduction of others. The visual power of the fishes is
especially apt to suffer degradation. This degradation may be
organic, a positive degeneration of the visual apparatus, as in
Ameiurus, or it may be merely functional. In the latter case,
though the organs of vision are not necessarily modified, these
organs are not actually used in procuring food, the fish being
unable to effect visual reflexes toward food substances or to cor-
relate visual stimuli with the movements necessary to react to-
ward food substances. The fish may be perfectly able to effect
other visual reflexes, such as avoiding enemies, but is appar-
ently unable to understand the significance of food when per-
ceived by the sense of sight only. This particular central re-
flex path has never been developed, or has atrophied from dis-
use. Nature has here effected for the species something simi-
lar to what is accomplished in individual men occasionally by
disease, in the production of certain aphasias.
This study has been directed primarily toward the solution
of a simple physiological problem; but in a purely incidental
way some points of interest to comparative psychology have
come up. We have seen that in the cat fish, hake and tom
cod the reflex of seizing the food is normally set off by a com-
130 JOURNAL OF COMPARATIVE NEUROLOGY.
bined stimulus of tactile and gustatory end-organs. At first
the fish may react similarly to a pure tactile stimulus and the
tactile plus the gustatory. After a brief training, however, he
acquires the ability to discriminate between the former, which is
never followed by satisfaction, and the latter, which is followed
by the pleasure of feeding. Clearly the fish learns by experi-
ence. We find also some differences between the different spe-
cies of fishes in this respect, depending on the relative impor-
tance of the tactile and gustatory elements of the sensation com-
plex in the normal reflex life of the fish.
It would be interesting to inquire the part played by
memory in these reactions. In the case of Ameiurus, where
the tactile and gustatory elements of the reflex of seizing food
can be experimentally isolated by training, it would doubtless
g,
be possible to measure quantitatively the duration of the per-
sistence of this acquired discrimination. I have made no accu-
rate observations on this point, but can say in general that the
memory of these fishes seems to be fairly good. (By the term
memory I do not mean to prejudice the question of the part
played by consciousness here. The original reaction may be
largely or wholly an unconscious or automatic response and the
“memory”? may be an organic memory more closely allied to
habit). At the beginning of the tests’ with cotton the cat fishes
generally seized the cotton just as they did the meat. At the
close of the first day’s experiments they had learned to ignore
the cotton asa rule, and half an hour after the close of this se-
ries of tests they still would pay small attention to the cotton ;
but by the day following, if tested first with meat, they would
take the cotton for-a few times or would react to it slightly
during the first few tests, but would learn to let it alone sooner
than on the first day. But toward the close of the experiments
after several weeks of practice I rarely got any reaction at all
with the cotton under any circumstances, even if the fishes had
not been tested for several days. With the gadoids the num-
ber of experiments was much smaller and they were continued
for a shorter time, but I never got so good evidence of memory
of the discrimination. On successive days the tests were much
‘ie eS —— —
a
7 ——
Herrick, Zerminal Buds of Frshes. Thee
alike. The inability of the tom cod to remember to ignore a
tactile contact which is not followed by satisfaction so long as
the cat fish remembers a similar discrimination I take to be an
indication that the tactile element plays a much larger part in
the reflex complex in the gadoids. | The known distribution of
the terminal buds favors this view also, for while they are very
abundant on the barblets and body of the cat fish they are
rather sparse on the free fins of the gadoids and the general cu-
taneous nerve supply on the fins of these fishes is greatly in ex-
cess of the communis nerve supply.
I noticed also that all of the fishes.that ate freely in
captivity soon accustomed themselves to novel methods of feed-
ing and in the case of the cat fishes and the hake especially, as
soon as I approached their tanks after the experiments had
been in progress some time, the fishes would rise to the top of
the tank and eagerly await the expected food. This restless-
ness became so great with the cat fish that the experiments be-
came increasingly more difficult and there was evidence that
vision and possibly smell assumed greater importance after this
expectation of food had made its appearance.
From the experiments just summarized we may, I believe,
conclude that these fishes taste with the terminal buds essen-
tially as they do with taste buds within the mouth and thus we
have added the last link in the chain of evidence necessary to
fix the position of these sense organs, the morphological and
the physiological evidence giving concurrent testimony to the
essential isolation of this system from either of the other types
of cutaneous nerves. Weare not at present able to assert with
confidence the phylogenetic origin of the gustatory system of
nerves and sense organs, though the structure of the brain cen-
_ ters seems to favor the belief that the system has been differen-
tiated from the general visceral sensory type of nerves. Of this
it cannot be said that we have adequate proof and experience
teaches us that, in the absence of evidence, speculations in this
field are not very profitable.
As intimated above, the trend of most of the recent work
on the nervous system of the fishes accords fairly well with the
132 JOURNAL OF COMPARATIVE NEUROLOGY.
conclusions here expressed, with one notable exception. Mr.
EK. P. Atuis (’o1) has recently published an important paper
on certain features of the sense organs (particularly the am-
pullae of Lorenzinr) and cranial nerves of Mustelus, which
takes its departure from our present problem, as indicated from
the following quotation for the introductory paragraph :
‘I have long had a very decided impression, opposed to that of
most workers on the subject, that these ampullary organs must be ge-
netically related to the terminal buds of ganoids and teleosts rather
than to the pit organs of those fishes; and I thought that I should
easily be able to get some positive evidence of this in the general
course and position of the nerves that innervate them in advanced
selachian embryos. ‘This positive evidence I have wholly failed to get,
for the very simple reason that, in the main nerve trunks, I could not
distinguish in my sections the ampullary fibers from the lateral canal
ones. Disappointed in this at the very beginning of my investigation,
I nevertheless decided to quite carefully trace the lateral canals and
the nerves that innervate them and the ampullae, as far back as my
sections went, that is, nearly to the level of the first gill slit. Careful con-
sideration of these observations has fully convinced me, though indi-
rectly, that the ampullary organs do represent the terminal buds of
ganoids and teleosts, and not the pit organs.”
These conclusions have been criticised at some length by
JOHNSTON (’02) and by myself (this Journal, vol. XII, p. iii)
but ALrIs (’03) now returns to his original proposition fortified
by fresh facts from the study of the lateral line system of Polyo-
don, though the evidence is still all indirect. Fortunately, at this
time we are able to meet speculation with fact, and, as we have
seen above, to put the morphology of the terminal buds ona
secure foundation.
ALLIS’ argument rests ultimately on two main supports,
viz.: (1) the supposed homology of the cerebral center from
which the ampullary organs of selachians are innervated with
that from which the teleostean terminal buds are supplied ; and
(2) the supposed similarity of the ampullae themselves and the
terminal buds.
(1) On the first point Mr. Artis is able to oppose to the
observations of all students of selachian nerves that the am-
pullae are supplied from lateralis branches only the conjecture
that the twigs for the ampullary organs terminate in the brain
——=— =
Herrick, Zerminal Buds of Fishes. 133
in a special center, the so-called lobus trigemini, and that this
center is homologous with the structure of that name in Acipen-
ser and teleosts.
Now it proves that neither of these assumptions is true, or
at best they are only partially true. The ‘‘lobus trigemini”’
of elasmobranchs is homologous with the part so named in
Acipenser, but in both cases the part is a derivative of the
tuberculum acusticum and is related to the peripheral
nerves from lateral line organs. The work of JOHNSTON
leaves no room for doubt on this point, and we may adopt his
designation for this lobe, ‘‘lobus lineae lateralis.”” The so-
called lobus trigemini of certain teleosts (cyprinoids and silur-
oids) is now known to bea totally different structure (K1NGs-
BURY, 97; HERRICK, ’O1), a center for terminal buds, having
nothing to do with any part of the acustico-lateralis system. It
is termed by recent writers the lobus facialis, and, in view of
ALLIS’ perpetuation of the old confusion growing out of a
false nomenclature, we may well adopt the suggestion of
Houser (’o1), ‘‘The term “#zgemznal lobe has been so variously
used that it should be dropped from our nomenclature.”
We are fortunately no longer shut up to speculation re-
garding the exact relations of these nerve roots in selachians.
In the course of a report upon his analysis of the cranial nerves
of Squalus acanthias, STRONG (’03) writes, ‘“The ramus mandi-
bularis externus VII is apparently derived practically entirely
from the more dorsal of the two lateral line roots [of the
facialis], the ramus buccalis receiving the major part of the re-
mainder of this root, while the ramus ophthalmicus superficialis
VII is principally composed of the bulk of the more ventral
lateral line root. This would apparently negative the view that
the ampullary organs are modified end-buds and the dorsal root
-an end-bud root.”’ This destroys completely the foundations of
A.tts’ labored argument from the structure of the r. ophthalmi-
cus superficialis. In brief, we may conclude from the works of
Houser, JOHNSTON, STRONG and others, that the terminal bud
and lateralis centers in the brains of cyclostomes, selachians and
ganoids are as distinct as I find them to be in the teleosts and
134 JOURNAL OF COMPARATIVE NEUROLOGY.
that the ampullae of selachians are related to the lateralis and
not to the terminal bud centers.
(2) The supposed similarity of ampullary organs and ter-
minal buds we have already touched upon. The fact is that
these organs do not resemble each other in their well developed
adult forms in any known case. In embryonic or reduced con-
ditions the neuromasts may resemble terminal buds on account
of the absence or reduction of their hair cells. But even in
these cases the innervation in all instances where it is accurately
known removes the ambiguity perfectly. I repudiate most
emphatically the statement attributed to me by Mr. ALLIs
(’03, p. 662) that in any fishes nerve hillocks (neuromasts)
may be innervated by communis fibers. |The exact opposite I
regard as one of the most important and distinctive of the re-
sults which I have reached in my studies upon the nerve com-
ponents of fishes.
A.tts further argues for the similarity of the two systems
of sense organs on the ground of the resemblance in the mode
of the distribution of ampullary organs in very young elas-
mobranchs to that of terminal buds in adult ganoids (Amia)
and teleosts. This resemblance in distribution pattern un-
doubtedly exists, and AtLtis’ demonstration of the origin of
ampullary organs in the ontogeny of Mustelus diffusely scattered
over the cutaneous surface in the positions of the mouths of their
pores in the adult is a point of no small interest and impor-
tance. His description of pit lines in Mustelus in relations simi-
lar to the pit lines of ganoids and teleosts is also of importance,
showing, as I fully agree, that the ampullary organs cannot be
homologized with these pit lines.
But it by no means follows because the ampullae are not
homologous with the pit lines that they are therefore homolo-
gous with the terminal buds. In fact, my studies of Ameiurus
have shown that in this type, in addition to lateral line canals
and pit lines of strictly typical arrangement, there are two in-
dependent systems of diffusely scattered cutaneous sense organs,
which I have termed the small pit organs and terminal budsand
which are innervated by lateralis and communis nerves re-
Herrick, Zerminal Buds of Fishes. — 135
spectively. If we must seek for equivalents of selachian ampul-
lary organs, they may be found in these small pit organs, for the
two sets of organs agree in all essential points of structure and
innervation, save that in the adult the teleostean organs do not
sink down into deep tubes and become massed at their inner
ends into dense clusters, but retain more nearly the embryonic
condition of the selachian organs. A careful review of all of
the known facts will show that the two types of sense organs
(terminal buds and lateral line organs of various types)
may appear or vanish quite independently of each other.
In Autis’ last paper (02, p. 663) he rebuts JOHNSTON’s
criticisms in the following language. I have numbered the
items in the passage quoted for ease of reference.
*¢ (1) That end-buds are all innervated by fibers that ‘find their
central endings in the lobus vagi;’ (2) that all other forms of cutaneous
sense organs are innervated by fibers that ‘have their central ending in
the nucleus funiculi, tuberculum acusticum, or the cerebellum;’ (3)
that the respective centers for the lateral line and end-bud fibers are so
separate and stable ‘that it is utterly impossible for fibers or centers to
‘undergo modification” of any sort such as I understand ALLIs to
mean ;’ (4) that ‘It is impossible that these organs [end-buds and lat-
eral line or pit organs] should ever resemble one another in any other
than a superficial way ;’ (5) and that end-buds are organs ‘with visceral
function (e.g. taste),’ while all other sense organs are organs ‘with a
somatic function (e.g. touch, &c.)’, are certainly nothing more nor less
than deductions from the theory he seeks to establish in his several
works instead of established facts on which to base that theory.”
Now, nothing could be further from my desire than to en-
ter into this controversy in a spirit of captious criticism, yet I
think it can clearly be shown that there is a solid foundation in
fact for nearly every one of the contentions taken by JOHNSTON
in the passage quoted. And it should be clearly born in
mind that many of the most decisive facts to which I refer have
been brought to light since Mr. AtLtis first formulated his
theory of the genetic relationship between ampullary organs
and terminal buds. :
Now taking up the abuve points in serial order: (1)
We have accurate observations on this point in Acipenser
(JoHNSsToN, ’O1), Petromyzon (JouNsTon, 02), Gadus (HEr-
RICK, 00) and Ameiurus (HerRRICK, OI, the lobus faciali
136 JOURNAL OF COMPARATIVE NEUROLOGY.
ing a derivative of the lobus vagi) and I also have unpublished
observations on Anguilla, Carassius and other fishes in sufficient
numbers to make it plain that it is true generally that in all
teleosts possessing terminal buds these organs are innervated
from the lobus vagi or its derivative, the lobus facialis. And
there are no precise observations on the other side.
(2) The second point I think is abundantly established by
the works of all recent students of nerve components, particu-
larly those of StrRonG, JoHNSTON and HeErRIck.
(3) The third point is stated perhaps rather more strongly
than the facts at command permit; nevertheless, I think it
must be admitted that the metamorphosis of organs of touch,
particularly tactile hairs, into end organs for the perception of
mass movements of water (lateral line organs; cf. PARKER, ’03),
for the maintenance of bodily equilibrium (semi-circular ‘canals)
and for hearing presents far less of difficulty than the transfor-
mation of any of the organs of this series into gustatory organs.
For the organs of the first series are all stimulated by impacts
of a common type, differing only in mode of application,
rythmic character, etc., while the gustatory organ belongs to a
totally different modality.
(4) The fourth point we have touched upon above. What-
ever may be conceived abstractly as ‘‘possible,”’ it is clear that
in point of fact these two types of organs do not resemble each
other either in structure, innervation or central connections.
(5) Finally that the terminal buds are organs of taste is no
longer a matter of conjecture, but a fact of proof.
We may, then, summarize our examination as follows:
The morphological rank and functional significance of the terminal
bud system of sense organs is definitely fixed. They are in no
way related to any organs of the lateral line system (pit
organs, nerve hillocks, ampullary organs, etc.) but on the other
hand they are most intimately related to the taste buds within
the mouth. This relationship is shown by their identity in
structure, innervation, central connections and functions. On
the other hand, the phylogeny of the terminal buds is by no
means on so secure a foundation as that of the sense organs of
HerRIcK, Zermznal Buds of Fishes. 137
the acustico-lateralis system and much remains here for future
research to clear up. Wecan however advance with confi-
dence at least this negative conclusion, that the terminal buds
have not been derived from ampullary organs or any other
members of the acustico-lateralis system.
Denison University,
May 7, 1903.
MIT ERATURE. Cl LED:
ALLIS, EDWARD FHELPS.
or. The Lateral Sensory Canals, the Eye-Muscles, and the Peripheral
Distribution of certain of the Cranial Nerves of Mustelus laevis.
OS Via Soles ND
03. On Certain Features of the Lateral Canals and Cranial Bones of
Polyodon folium. Zool. Jahrb. Abt. f. Anat., XVII, 4.
BATESON, W.
*90. The Sense Organs and Perceptions of Fishes, with Remarks on
the Supply of Bait. Journ. Biol. Assoc., London, Vol. 1.
CLAPP, CORNELIA, M.
’99. The Lateral Line System of Batrachustau. /ourn. Morph., XV, 2.
HERRICK, C. JUDSON.
’99-~=0 The Cranial and First Spinal Nerves of Menidia; A Contribu-
tion upon the Nerve Components of the Bony Fishes. Journ. Comp.
Neurol., 1X, 3-4.
700. A Contribution upon the Cranial Nerves of the Cod Fish.
Journ. Comp. Neurol., X, 3.
’o1r. The Cranial Nerves and Cutaneous Sense Organs of the North
American Siluroid Fishes. Journ. Comp. Neurol., XI, 3.
702. The Sense of Taste in Fishes. Abstract. Sczence, N. S., XVI,
No. 400.
Houser, G. L.
’o1. The Neurones and Supporting Elements of the Brain of a Se-
lachian. Journ. Comp. Neurol, XI, 2.
JounstTon, J. B.
?o1. The Brain of Acipenser. Zool. Jahrb., Abt. f. Anat., XV.
’o2. The Brain of Petromyzon. /ourn. Comp. Neurol., XII, 1.
‘o2 a. An Attempt to Define the Primitive Functional Divisions of
the Central Nervous System. /ourn. Comp. Neurol., XII, I.
702 b. The Homology of the Selachian Ampullae. A Note on Allis’
Recent Paper on Mustelus laevis. Azat. Anz., XXI.
KInGSpury, B. F.
97. The Structure and Morphology of the Oblongata in Fishes.
Journ. Comp. Neurol., V\1. 1.
138 JOURNAL OF CoMPARATIVE NEUROLOGY.
LEYDIG, FR.
51. Ueber die fussere Haut einiger Siisswasserfische. Zetts. f. wiss.
Zool., 11.
’79. Neue Beitraige zur anatomischen Kenntniss der Hautdecke und
Hautsinnesorgane der Fische. Festschr. Naturf. Ges. zu Halle.
’94. Integument und Hautsinnesorgane der Knochenfische. Weitere
Beitrige. Zool. Jahrb. Abt. f. Anat., VIII, 1.
MERKEL, FR.
*So. Ueber die Endigungen der Sensiblen Nerven in der Haut der
Wirbelthiere. Rosvock.
MorriL., A. D.
95. The Pectoral Appendages of Prionotus ant their Innervation.
Journ. Morph., X\.
PARKER, G. H.
’03. The Sense ot Hearing in Fishes. Am. Nat., XXXVII.
’03. Hearing and Allied Senses in Fishes. WU. S. Fish Commyssion
Bulletin for 1902, Washington, 1903.
SCHULZE, F. E.
763. Ueber die becherférmigen Organe der Fische. Zezts. f. wiss.
Zool., X11.
’67. Epithel- und Driisenzellen. Arch. f. mikr. Anat. II. (Argues
that terminal buds on the outer skin of fishes are gustatory and serve to
localize the source of the stimulus.)
’70. Ueber die Sinnesorgane der Seitenlinie bei Fischen und Amphi-
bien. Arch. f. mtkr. Anat., VI.
STRONG, O. S.
‘03. The Cranial Nerves of Squalus acanthias. Abstract. Sczence, N.
So x VILS No 424.
ON TE NAUK (OF. THE PERICELLULAR NET-
WORK OF INERV EE (CELAS:
By SHINKISHI HATAI.
(from the Neurological Laboratory of the University of Chicago.)
With Plate III.
In 1895 HeELp announced that the nerve cells in the cen-
tral system are densely surrounded by the terminals of the
axones which divide into fine branches and form by a local
union a complicated network. He also described the club-
shaped enlargement of the axone terminals which may be seen
in the embryonic nervous system. These terminals, or ‘‘Axen-
cylinderendflache,’’ are characterized by the presence of the
minute granules or neurosomes which stain red by erythrosin.
The terminal network or ‘‘Pericellular network,’”’ or ‘‘Gotuer-
netz of BETHE” is very well shown by BeruHe’s molybdenum
technique, as well as by Gorai’s modified silver technique.
The appearances produced by the. foregoing methods are
somewhat different from those obtained by the method of
Hep. This difference in appearance may be due to the fact
that both Gouer’s and Brrue’s technique cover over the finer
and more complicated structures by the precipitation of silver
chromate or the molybdenum compound respectively, and thus
bring out strongly marked and rather angular meshes of the
network. The nature of these networks obtained by HE Lp,
Gore! and Berue will "be described later on.
I have also noticed and described this pericellular network
which not only surrounds the PuRKINJE cells and the cells in
the corpus trapezoideum, but also the cells in the Ammon’s
horn and those in the ventral cornua of the spinal cord (03).
HeELp’s idea that the finer network which surrounds the
140 JoURNAL OF COMPARATIVE NEUROLOGY.
cell-body and :orms the pericellular network, is composed of
the terminals of the axones, and that the granules which stain
red are seuroplasm, has been criticized by ApATHy. APATHY
thinks the Axencylinderendflache to be nothing more than
the neuroglia fibers which very frequently surround the
cell-body as well as the dendrites, and thus denies the nervous
nature of HeELp’s pericellular network.
He says: ‘‘In Betreff der von HELD beschriebenen peri-
cellularen Ausbreitungen des Axencylinder und in Betreff der
Neurosomen desselben Autors, kann ich indessen versichern,
dass erstere nichts mit dem Axencylinder, letztere nichts spezi-
elleres mit dem Nervosen tberhaupt zu thun haben. Jene
Ausbreitung sind ein Gliagitter (die Neuroglia im urspriing-
lichen weiteren Sinne verstanden), welches von dem Axen-
cylinder, den es wahrend seines Weges im Centralnervensystem,
ausserhalb der Myelin Scheide, umhiult, auf den Zellkorper der
Ganglienzelle tibergeht und sich auf die sonstigen Auslaufer der
Ganglienzelle, auf die Dendriten, fortsetzt. Ein ahnliches, die
Ganglienzellen eng umschliessendes Gliageflecht habe ich auch
bei Hirudineen beschrieben und es als die Gliazone der Gangli-
enzellen bezeichnet, welche auch in das innere der Ganglienzelle
Fortsatze senden kann, aber nicht eigentlich zur Ganglienzellen
gehort und nicht mit dem Neurofibrillengitter zu verwechseln
ist. Durch dieselbe Gliazone der Wirbeltierganglienzelle ist,
wie ich glaube, auch die von Gore! durch Chromsilber darge-
stellte und urlangst beschriebene Gitterhille bedingt.”’
This criticism of ApATHy is, no doubt, one objection to
HE Lp’s hypothesis, since, as has been pointed by ApArny, the
cell-bodies are intimately surrounded by the neuroglia fibers.
Furthermore, HELp’s technique is not suited to distinguish the
neuroglia fibers from that of the pericellular network, although
he claims that these two structures stain differently.
Recently HeEtp published an elaborate article ('03) in which
he not only criticised the results obtained by various investiga-
tors, but also confirms fully his own earlier observations. He
employed several different methods for both staining and fixing,
especially Gotci’s modified silver method and Berue’s tech-
Harta, Nature of the Pericellular Network. 141
nique were used. The paper is accompanied by a large num-
ber of drawings made from his own preparations. In some
cases, he noticed a direct continuation of the pericellular net-
work by way of terminals with the medullated nerve fibers.
Thus he proves conclusively that one set of structures forming
the pericellular network is composed of the terminals of the
axones, and, in other words, this particular network is nervous
in nature. BETHE (00) also showed a direct continuation of
his ‘‘primitive neurofibrils’’ into the Golginetz. BETHE here
used his own molybdenum technique. It is therefore evident
that the weight of opinion is in favor of the nervous nature of
the network and against the view of APATHY.
Another objection to the view of HELp has been raised by
BETHE (00). Although he agrees with HeELp in considering
the pericellular network to be composed of the terminals of the
axones represented by the primitive neurofibrils, yet he does
not accept the delicate meshwork structure formed by the
union of the side branches of the axone terminals as well as
the presence of the neurosomes. HELp’s answer to this criti-
cism is not a satisfactory one and demands further evidence. —
My own results obtained from the studies on the preparations
stained with a new technique, reveal several facts which support
very strongly HeEtp’s idea as well as my own observations pre-
viously published ('03), and are opposed to the views of
ApATuy and BETHE.
The staining reagents used for the present investigation
were prepared by the following way :
Minced sheep’s brains were boiled in 10% formalin for
several days on the water-bath. The solution was filtered
off while hot. A concentrated aqueous solution of ammonium
molybdenum in excess was added together with a few drops of
HCl and the solution boiled again. The solution is at first
yellow and then turns to a blue color. After continued boiling
(at least 24 hours) an intense blue color is produced. The na-
ture of the substance which gives the blue color has not yet
been determined. The preparation is stained with the blue so-
lution thus obtained, in the following way: The materials are
142 JouRNAL OF COMPARATIVE NEUROLOGY.
fixed with 10% formalin and the sections are made by either
paraffin or celloidin technique according to the usual procedure.
The sections are first treated for several minutes with dilute hy-
drochloric acid, and then transferred to the blue solution where
they remain for 24 hours. If the section is over-stained, it
_may be decolorized with 1% potassium permanganate for a
second, and the further oxidation is stopped by transferring the
section into dilute hydrobromic acid. The preparation thus
stained brings out the structures described below.
Unless otherwise mentioned, the following description is
based on the observations of cells from the spinal cord of the
dog. 34° ay” eid at
Ce Ot OB} ot Bee O
s
re
é
1@
\e
Fig.3
LITERARY NOTICES.
Hearing and Allied Senses in Fishes.!
The moot question whether fishes possess the sense of hearing has
been attacked experimentally by PARKER with the result that he gives
a definite affirmative answer for some types of teleosts. This report
will impress the reader as a particularly clean piece of experimental re-
search and the conclusions seem to be free from any reasonable ques-
tion. ‘The experiments were ingeniously planned, carefully controlled
and skilfully performed. The general methods of the research, as well
as the conclusions, can be gathered from the author’s summary of re-
sults, which we quote:
1. Normal Fundulus heteroclitus reacts to the sound waves from a
tuning-fork of 128 vibrations per second by movements of the pectoral
fins and by an increase in the respiratory rate. It probably also re-
sponds to sound waves by caudal fin movements and by general loco-
motor movements.
2. Individuals in which the eighth (auditory) nerves have been
cut do not respond to sound waves from the tuning-fork.
3. The absence of responses to sound waves in individuals with
severed eighth nerves is not due to the shock of the operation or to
other secondary causes, but to the loss of the ear as a sense organ.
4. Fundulus heteroclitus therefore possesses the sense of hearing.
5. ‘The ears in this species are also organs of prime importance
in equilibration.
6. Normal Fundulus heterochtus swims downward from the top of
the water and remains near the bottom when the aquarium in which it
is contained is given a slight noiseless motion.
7. Individuals in which the nerves to the lateral-line organs have
been cut will swim upward or remain at the top while the aquarium is
being gently and noisclessly moved.
8. The lateral-line organs in this species are probably stimulated
1 Parker, G. H. Hearing and Allied Senses in Fishes, U. S. Fish Com-
mission Bulletin for 1902, Washington, 1903, pp. 45-64-
xxii JouRNAL OF ComPaARATIVE NEUROLOGY.
by a slight mass movement of the water against them. They are not
stimulated by sound waves such as stimulate the ears. ‘
g. Individuals in which the nerves to the lateral-line organs have
been cut swim downward and thus escape from regions of surface wave
action. ‘They also orient perfectly in swimming against a current.
Since surface waves and current action stimulate fishes in which the
nerves to the lateral-line organs and to the ears have been cut, these
motions must stimulate the general cutaneous nerves (touch).
10. The vibrations from a bass-viol string when transmitted to
water stimulate the ears and the lateral-line organs of Fundulus. They
also stimulate mackerel and menhaden, but not the smooth dog-fish,
which responds only when in contact with solid portions of an aquarium
subjected to vibrations.
We have another interesting set of observations in Professor
TULLBERG’S paper on the Functions of the Labyrinth in Fishes.’
The author operated on various teleosts by cutting the semi-circu-
lar canals, removing the large otolith and in various other ways and
concludes that the labyrinth is not an organ of equilibrium, or of the
static sense or for the maintenance of muscular tone or of the
spacial sense in the sense of v. Cyon. It is probably to some degree
an auditory organ (though he gives no satisfactory proof of this).
‘Originally and primitively, however, the labyrinth of fishes is a sense
organ for the perception of movements of the surrounding water, since
currents are apparently perceived by the cristae acusticae of the am-
pullae, but wave movements probably by the maculae acusticae of the
utriculus, the sacculus and the lagena. The central organ for this
sense organ is apparently the cerebellum.”
That the labyrinth is primarily an organ for the perception of cur-
rents or streaming movements of the surrounding medium seems on
a priort grounds highly improbable, since the stimulus is one which
may easily act upon the skin, lateral-line organs or other superficial
sense organs, but only with difficulty on the deep-seated labyrinth.
Moreover the experiments cited seem inconclusive. In the first
place, the canals were merely cut and the nerve endings were not de-
stroyed. The same applies to the removal of the otolith. In several
of these experiments there were forced movements and disturbances of
equilibrium which the author has to explain away. In general too the
lesions were symmetrical. More radical operations would seem to be
? TycHo TULLBERG. Das Labyrinth der Fische, Ein Organ zur Empfindung
der Wasserbewegungen. SBithang till K. Svenska Vet.-Akad. Handlingar, Stock-
holm, Bd. 28, Afd. IV, No. 15, 1903.
Literary Notices. XXill
necessary before permitting the conclusion that the labyrinth is not
concerned in equilibration and the static sense. In experiment 12,
designed to show that orientation with reference to water currents is
not done by the lateral-line canals, the n. lateralis vagi was cut behind
the shoulder girdle, with the result that the operated fishes still oriented
themselves with reference to currents like normal fishes. But it should
be noted that in this experiment the canals of the head, of far greater
extent and importance, were uninjured.
Professor TULLBERG’S experiments are criticised at some length by
Dr. PARKER in connection with a brief report upon his own experi-
ments recently published in the American Naturalist. !
A physiological and morphological classification of all of the cuta-
neous sense organs of fishes as conceived by the present writer is now
in press in the current number of the .\merican Naturalist, and the
status of such of these organs as belong to the communis or gustatory
system is treated more at length in another place in this issue of this
Journal. Fe Be
Taste Fibers and Their Independence of the Trigeminus.?
The surgical work and clinical observations upon which this re-
port is based seem to have been more carefully planned and more skil-
fully wrought out for the solution of the problem of the course of the
taste fibers than any of the preceding contributions to this difficult
theme. In most of these cases a preliminary test of gustatory sensi-
bility was made before the operation—a most necessary precaution, as
the event proved. ‘The patients were whenever possible kept under
observation and repeatedly tested tor long intervals after the operation.
The results in all of the cases furnish a strikingly clear proof of the the-
sis stated in the title, without the confusion and ambiguity of most pre-
vious reports.
In general there is a post-operative transient period of total or
partial abolition of taste perception, with a gradual return to the nor-
mal gustatory sensibility, but no return of tactile sensibility. He says,
“T find it difficult to reconcile my fairly uniform results, that is, uni-
form in so far as the ultimate preservation of taste is concerned, with
the contradictory observations which have been made by so many
* PARKER, G.H. The Sense of Hearing in Fishes. Am. Nat., XXXVII,
No. 435, March, 1903.
* CusHING, Harvey. The Taste Fibers and their Independence of the
N, Trigeminus. Deductions from Thirteen Cases of Gasserian Ganglion Extir
pation. Johns Hopkins Hospital Bull., X1V, No. 144, 145, 1903, pp. 71-78.
XXiVv JouxNnaL oF ComPARATIVE NEUROLOGY.
others lhe only explanation which I can offer is that there may be
in a considera -ercentage of the cases a temporary diminution in
its acuity or a complete abolition of taste as has been intimated above,
and that this may have been interpreted under certain circumstances
as an evidence of permanent loss of this sense.”
The conclusions are: 1. That the perception of taste is unaf-
fected on the posterior portion of the tongue and never permanently or
completely lost on its anterior two-thirds after removal of the Gasserian
ganglion.
2. ‘That the temporary abolition or lessening of the acuity of
taste may be found to exist over the anterior and anaesthetic portion of
the tongue for some days after the operation.
3. That this temporary loss of function may possibly be occa-
sioned by some interference with chorda transmission brought about
by a mechanical or toxic disturbance due to degeneration of the N.
lingualis.
4. Thata lesion of the trigeminal nerve may be associated with
disturbance of taste over the chorda territory without the necessary in-
ference that the nerve is a path for gustatory impulses.
5. That the N. trigeminus in all probability does not convey
taste fibers to the brain either from the anterior or posterior portion of
the tongue. .
This last conclusion, it will be noted, has been reached almost
uniformly of late by researchers in three independent lines of work,
the morphologists, the embryologists and the comparative anatomists,
and it is a source of satisfaction to see the confusing clinical evidence
at last brought into harmony with these in so unambiguous a manner.
Cee
De Fursac’s Psychiatry.’
Almost every language has had its little compend based on the re-
markable changes in psychiatric views, produced by rather a daring
but decidedly inspiring reform started by KRAEPELIN. This little book
adopts the classification of KRAEPELIN, which is partly etiological, but
largely a grouping of the mental diseases according to their outcome.
The little book has in some respects an intrinsic value, owing to the
attempts at harmonizing current French views with those of the Heidel-
berg school. The book is dedicated to Professor Jorrroy, and is in a
way a semi-official acknowledgement of KRAEPELIN’S attitude.
A. M.
1 Manuel de Psychiatrie, by Dr. RoGues De Fursac. farts, F. Alcan,
1403.
Literary Nottces. XXV
The Evolution of Man and his Mind.!
This bulky volume, which contains much that is admirable, is de
signed to be a popular exposition of the course of human evolution,
particularly from the point of view of certain sociological defects of
our present status. This makes a striking background for an exposé
and arraignment of certain corrupt tendencies in our political and so-
cial organization. ‘The literary style is colloquial and catchy and the
book should do good in directing popular attention toward these abuses.
As a whole, however, it is so ill-balanced and full of inaccuracies that
it can hardly be commended as a helpful scientific contribution.
CL Me
The Brain and Nerves of the Anamnia.?
Professor JOHNSTON’s summary of recent progress in our knowl-
edge of the central and peripheral nervous system of the Ichthyopsida
is one of the notable papers of the year. The point of view from
which he writes is so distinctively his own that his article is more than a
mere abstract or critical review ; it is a positive contribution toward the
solution of some of the major problems of comparative morphology.
This point of view he has already presented in this Journal (March,
1902), under the title, ‘An Attempt to Define the Primitive Functional
Divisions of the Central Nervous System,” being essentially the corre-
lation of central with peripheral differentiation of the nervous system.
We venture the prediction that the next decade will see this principle
worked out successfully in several fields at present open merely to the
methods of descriptive anatomy. ‘lhe conclusions of students of
nerve components as formulated at the present moment may or may
not stand the test of time, but the esseutial aims and methods of work
which they have introduced into comparative neurology will surely in
the end yield results of permanent value. Professor JOHNSTON's
Referat is therefore very timely. Gi Fi
1 CLEVENGER, S. V. The Evolution of Man and his Mind. A History
and Discussion of the Evolution and Relation of the Mind and Body of Man
and Animals. Chicago, 1903.
2 Jounsron, J. B. Das Gehirn und die Cranialnerven der Anamnia.
Merkel und Bonnet’s Ergebnisse, Bd. XI, for wor. MWresbaden, 1902, pp. 973-
1852.
XXVi JouRNAL OF COMPARATIVE NEUROLOGY.
The Dorval Spino-cerebellar Tract.'
Sections of the sprmal cords of dogs at different thoracic and cervi-
cal levels show that the longest fibers of the’ direct dorso-lateral cere-
bellar tract, i. e., those arising in the lowest levels of the spinal cord,
are most superficial in position and that the shorter fibers are added
successively along the inner side of this zone.
The authors verify previous findings of degeneration in the cells
of CLARKE’s column below the lesion after section of the dorso-lateral
cerebellar tract. In these cases the fibers of the tract between the de-
generated cells and the lesion show no degeneration under the MARcul
procedure, WEIGERT stain, anilin blue-black, picrocarmine, etc. To
test the condition of these fibers further the authors made a right lat-
eral transection of the Xth thoracic segment 260 days subsequent to a
total transection at the IId thoracic level. The animal (dog) was sac-
rificed 20 days after the establishment of the second lesion. The
right cerebellar tract above the second lesion was found fully present-
ing all the signs of WALLERIAN degeneration under the MARCHI re-
action. The left cerebellar tract appeared normal and without any
degeneration. ;
‘It would seem therefore that atrophy, severe and long-lasting,
probably permanent, of CLAaRKE’s cell-column induced by spinal tran-
section in the the lower cervical or upper thoracic region, far from de-
stroying the dorsal cerebellar tract, leads to no obvious or easily de-
monstrable degeneration of at least the main body of the fibers of the
tract. Further, after the severe atrophy of CLARKE’s column has set
in and become established, transection of the tract in the very region
of atrophy of the cell-column still causes full WALLERIAN degeneration
of the fibers head-ward of the transection.” These results obviously
have an important bearing on the theory of the physiology of the neu-
rone and its biological interpretation. CC. 4
The Optic Chiasma in Symmetrical and Asymmetrical Teleosts.*
The author in continuing his observations on the optic chiasma of
fishes develops several results which bear directly onthe morphology
and phylogeny of the flat fishes. He has previously shown’ that in
* SHERRINGTON, C. S.and LAstetr E. E. Remarks on the Dorsal Spino-
cerebellar Tract. Journ. of Physiol., XXIX, 2, March, 1903.
2 Parker, G. H. The Optic Chiasma in Teleosts and its Bearing on the
Asymmetry of the Heterosomata. Aull. Mus.;Comp. Zool., XL, 5, 1903.
’ The Crossing of the Optic Nerve in Teleosts. Biol. Bull., 11, 1901, pp.
335-336.
Literary Notices. XXVii
the symmetrical teleosts the right and left optic nerves are dorsal in an
approximately equal number of cases. He now extends the observa-
tions to the flat-fishes and finds that the two families into which the
sub-order Heterosomata is divided by recent systematists differ con-
spicuously in this character. In the Soleidae the chiasmata are di-
morphic, as in symmetrical teleosts; i. e., the right optic nerve is dor-
sal in abeut half of the observed cases and ventral in about half. In
the Pleuronectidae, on the other hand, the chiasmata are monomorphic
for each species; in dextral species the left nerve is dorsal, in sinistral
species the right nerve is dorsal. All species of this family that turn
in only one direction have their dorsal nerves connected with their
migrating eyes. In all species that have both dextral and sinistral in-
dividuals, the dorsal nerve is connected with that eye which in the
greatest number or in the nearest of kin migrates. The unmetamor-
phosed young of the Pleuronectidae are not symmetrical in the same
sense that symmetrical teleosts are, for they have monomorphic chias-
mata. ‘The Soleidae are not degraded Pleuronectidae, but degenerate
descendants of primitive flat-flshes, from which the Pleuronectidae
have probably been derived. The monomorphic condition of the
optic chiasma of the Pleuronectidae can be explained only on the as-
sumption of natural selection. The flat-fishes afford striking examples
of discontinuous variation. ae Fear”
Brain Weights of Eminent Men.’
Dr. SpirzKa has tabulated 96 cases and made comparisons with
the statistics of 800 brains of ordinary persons as given by BISCHOFF
and MaRCHAND. ‘‘ The average (arithmetical) brain weight of the 96
individuals is 1473 grams, exceeding the various averages given for the
European brain by 75 to 125 grams, and this without allowing for the
advanced age of this series; the average of 92 being 63 years.” ‘‘Itis
further shown that the period of decrease [in brain weight] with age is
deferred for fully a decade among the more intellectual persons, a
point already alluded to by Dona.pson, and significant in connection
with the longevity of healthy persons endowed with high intelligence.”
The paper is accompanied by several instructive curves and tables.
5 ee
* Spitzka, Epwarp ANTHony. A Study of the Brain Weights of Men
Notable in the Professions, Arts and Sciences. Philadelphia Medical Journal,
May 2, 1903. : * ot th
XXVili Jounnat or Comparative NeuRoLocy.
The Lateral Neasory Syvtem of the Eels.'
in this paper of 48 pages and three good"plates we have a detailed
description of the lateral line canals and associated sense organs in the
conger ee] and a more brief account of three related species of Mu-
raenidae, viz., Ophicthys serpehs, Myrus vulgaris and Muraena helena.
The nerves supplying these sense organs have been traced only in their
peripheral portions and we are promised a later research upe the i in-
nervation of these structures in the conger.
In connection with the innervation of the pit organs shete is is one
correction of minor importance on page 42 of the reprint, to which at-
tention might be drawn. Mr. ALLis describes a pit line running paral-
lel with the squamosal lateral canal which is innervated by a nerve
formed from an anastomosis between a branch of the facial, which is re-
garded as a portion of the ramus opercularis facialis, and a branch of
the glossopharyngeus or vagus. In discussing the morphology of these
pit organs the author says, ‘‘If they be pit organs, it is practicully cer-
tain that they cannot be innervated by the facialis, for there is no sin-
gle instance that I know of, of lateral sensory fibers accompanying the
ramus opercularis of that nerve.” As amatter of fact I have described
just such a condition in Menidia (this Journal, vol. 1X, p. 294, seqq.),
BauDELoT’s descriptions strongly suggest the same thing, and I have
no doubt that a careful search of the literature would reveal other such
cases. Confusion arises in this connection (and this is the occasion of
this note) from the fact that there are two opercular rami in teleosts
which are not always distinguished. ‘The ramus opercularis profundus
VII is a purely motor nerve, and this is the only one of these branches
which is mentioned by Srannius. On the other hand, the ramus
opercularis superficialis VII is a mixed nerve, containing in Menidia
both general cutaneous and lateralis fibers and in other cases appa-
rently it may contain communis fibers also or be fused with the motor
fibers belonging to the ramus hyoideus VII. This superficial nerve
frequently anasomoses with the vagus or glossopharyngeus and in
Menidia at any rate it is clear that the vagal ae are all of general
cutaneous nature. C.J. Be
1 Auuis, E, P. The Lateral Sensory System inthe Muraenidae. J#éern.
Monatsschrift f. Anat. u. Phystol., XX, 4-6, 1903.
VotuME XIII. 1903. NUMBER 3.
THE
JournaAL oF Comparative Neurovoey.
THE NEUROFIBRILLAR STUCTURES IN THE GAN-
GEA’ OR THE LEECH (AND: CRAYFISH WITH
ESPECIAL REFERENCE TO THE NEURONE
RHEORY.
By C. W. PRENTIss,
Parker Fellow in Zoéblogy, Harvard University.
With Plates V and VI.
A previous publication treats in detail of the fibrillar net-
works in the neuropil of the leech. In the present paper it is
purposed to give amore general description of the fibrillar struc-
tures found in the nervous system of the leech and crayfish and
to point out the relation of these structures. to the neurone
théory.
The neurone theory, grounded upon the fundamental re-
searches of GuDDEN, GotGI, and His, was first formulated by
WALDEYER (’g!) in the following words: ‘‘Das Nervensystem
besteht aus zahlreichen, unter einander anatomisch wie gene-
tisch nicht zusammenhangenden Nerveneinheiten (Neuronen).”’
As WALDEYER, VERWORN, and Nisst have shown, the all-impor-
tant point embraced in the neurone theory is not the anatomical
independence of the nervous elements, but the assumption that
the nervous system is entirely composed of cell individuals.
Whether the processes of these cells are only in contact, or by
growing together have become continuous, is a secondary mat-
ter. Nevertheless, on the threefold evidence of histogenesis,
neuropathology, and histology, most neurologists maintain that
the nervous system is composed of anatomically independent,
cellular units.
1. Hustogenesis. That the nerve elements develop from
single neuroblasts and not from chains of cells was first asserted
158 JoURNAL oF CoMPARATIVE NEUROLOGY.
by His (’89, ’90). His work has recently been confirmed by
the excellent research of Harrison (:01). The latter was
able to show that in two cases dorsal processes from bipolar
neuroblasts of the sensory ganglion broke through the bound-
ing membrane of the nerve chord, while ventral processes from
the same cells were traced to the periphery. Both His and
Harrison have proved that the axis-cylinders and dendrites of
motor elements originate as processes from a single cell; they
traced the axis-cylinder processes to the very point where the
nerve fibers appear; but in no case did either investigator de-
monstrate direct connection between these processes and the
embryonic nerve fibers. Harrison states moreover that: ‘‘Die
ersten motorischen Fasern sind schon vorhanden, ehe wuber-
haupt lose Zellen in der Gegend der Austrittsstelle zu finden
sind.”
Directly contrary to the observations of His and Harri-
SON, and in agreement with those of BALFour (’76) and DoHRN
(91) are the preliminary statements of BeTHE (: 02) as to the
histogenesis of the nerve elements in the chick: (1) Before the
axis-cylinder processes of the neuroblasts break through the
bounding membrane of the chord, the fundaments of nerve
fibers are formed as chains of cells; (2) coincident with the
breaking through of the processes, many primitive fibers may
be observed in the myotomes; (3) processes of the bipolar
cells which form these nerve fibers in the myotomes may be
traced into the chord with the same distinctness with which the
processes of the neuroblasts (of His) may be traced out of it,
and often the union of processes from neuroblast and primary
nerve cell may be observed; (4) the primitive nerve fibers are
differentiated simultaneously from an entensive chain of cells
extending from the central organ to the periphery; (5) these
cells increase in number only by karyokinesis ; not until the 7th
to goth day of development are the neuro-fibrillae formed.
BETHE concludes from these observations that each nerve ele-
ment represents a group or society of cells, rather than a single
cell individual. His statements are as yet unsupported by pub-
lished figures, but they agree both with the observations of
PRENTISS, Weurofibrillar Structures. 159
other noted neurologists and with his own recent work on the
regeneration of peripheral nerves. It is at least clear that as
far as the evidence of histogenesis goes the neurone theory is
still open to dispute. It is grounded on certain recognized facts,
but these facts relate only to the early stages of development.
Neither His nor Harrison says anything as to the origin of the
neurofibrillae, structures upon which the opponents of the reu-
rone theory put much weight.
2. Neuropathology. GUDDEN (’89) was the first to demon-
strate the fact that the cutting of a motor axis-cylinder caused
the degeneration not only of the peripheral fiber, thus isolated
from its cell, but also of the cell and its dendrites. In new-born
animals the entire nerve element atrophied and was resorbed,
but never in any case were the pathological changes observed
beyond the dendrites of the injured neurone. According to
Niss_, Foret (’86) first coupled these facts with the evidence
of GoLGi’s preparations and formulated the idea of the nerve-
cell individual, to which WALDEYER later gave the name of neu-
rone. The two facts of neuropathology which have been used
as arguments in support of the neurone theory are: (1) that
nerve fibers separated from their ganglion cells degenerate and
(2) that the phenomena of degeneration never have been ob-
served to pass beyond the processes of the injured elements.
The experiments of GupDEN show that it is not merely
their isolation from their cells which causes nerve fibers to degen-
erate, for the cells themselves often atrophy in young animals.
BETHE ('98) by isolating the neuropil of a nerve center in the
brain of the crab found that the nerve elements may remain
actively functional for several days, proving that the nerve ele-
ments are physiologically independent of their cells. His re-
cent experiments in neuropathology, of which he has given
only a preliminary account (: 02), show that peripheral nerves
will degenerate some time after isolation from their nerve cells;
furthermore, that in the young dog such degenerate nerve fibers
will, in the course of 6 to g months, regenerate all the structures
of anormal nerve fiber—primitive fibrillae, perifibrillar substance and
Schwann's sheath. Not only are the regenerated fibers normal
160 JOURNAL OF COMPARATIVE NEUROLOGY.
in structure, but stimulation of the distal stump of the nerve
(Ischiadicus) causes contraction of the muscles which it sup-
plies. Upon dividing the regenerated nerve a second time,
degeneration ensued in the distal portion only. By this evi-
dence of BETHE’s the phenomena of degeneration, in themselves,
are rendered worthless as arguments in support of the neurone
theory, while his observation of the regeneration of peripheral
nerves is incompatible with the assumption that each nerve
fiber develops in its entirety as a process of a single ganglion
cell.
That the phenomena of degeneration have not been ob-
served to pass beyond the dendrites of the injured nerve ele-
ments is most easily accounted for by assuming the non-exist-
ence of continuity between the dendrites of the nervous ele-
ments. But, as Nisst argues, the opponents of the neurone
theory may, with equal right, assume the presence of connecting
fibrillar structures in the central organ, of whose peculiar qual-
ities we as yet know nothing, at least in vertebrates. These
structures (the ‘‘nervose Grau” of Nissx) are differentiated cell
products, and as they are independent of the ganglion cells,
they are immune from the pathological changes which affect the
processes of the latter. What are the histological facts in sup-
port of these assumptions ?
3. Astology. We have seen that the neurone theory
was based by Foret and WaLDEYER mainly upon the discov-
eries of His, and the silver impregnations of GoLai and Ramon
y CajaL. It is now known that the methods of GOLGI are ex-
tremely unreliable, that the impregnations are rarely complete
and often extend to non-nervous structures. When, therefore,
ApATuHy ('97) demonstrated by new methods the finer structure
of the nervous system, many neurologists maintained that
the neurone theory had received its death blow. The
value of ApATHY’s work, however, has been in throwing into
doubt the evidence of GoLG! preparations, and showing the
importance of more certain and refined methods for the study
of the nerve elements. APATHY proved that the supposed
nervous units of GoLGi preparations are themselves composed
PRENTISS, Weurofibrillar Structures. 161
of infinitely smaller conducting elements, the primitive fibrillae,
which form networks in the cells. He also figured cases of
direct communication between the processes of nerve cells in
the intestine of Pontobdella and instances of fibrillar networks
in the neuropil of A/zrudo.
In addition APATHY maintains the existence of large motor,
and small sensory, fibrillae; these two types of fibrillae are
connected with each other by networks in the ganglion cells
and by the diffuse fibrillar network which, according to APATHY,
forms the neuropil proper.
The existence of the neurofibrillae is now generally admit-
ted. BETHE (’98) confirmed ApAtruy’s observations as to the
presence of the fibrillae in both the nerve cells and fibers, but
could not distinguish between motor and sensory fibrils in the
crab, Carcinus. He also asserts that the fibrillar networks in the
neuropil are not diffuse. His series of studies on the neuro-
fibrillae in the nervous elements of vertebrates (’98a, '99, : 00)
leads him to the conclusion that they are invariably present,
but that the networks characteristic of invertebrate nerve cells
are rarely found. He suggests that the neurofibrillae of the
cells may be directly connected with the fibrillar ‘‘Golginetze’’
which surround the cells, and that these in turn may be in com-
munication with the fibrillae of other (sensory) elements.
Neither BETHE nor Nissi was able to demonstrate a clear case
of such fibrillar connection, and the assumption that the
‘‘Golginetze’”’ are composed of neurofibrillae has been severely
criticized by Ramon y Caja and others. NIssL (: 03) assumes
the existence, in the central organ, of ‘‘nervous gray”’ struc-
tures, the differentiated products of nerve cells, corresponding
perhaps to ApATHY’s diffuse fibrillar network. The assumption
that such nervous elements exist, is based entirely on theoreti-
cal grounds. He points out that it has never been proved that
the neurofibrillae of the nervous system are integral parts of
the nerve cells, but that there are facts which indicate that they
are not: (1) the fibrillae are sharply marked off from the rest
of the cell in both structure and staining qualities; (2) the axis-
cylinders are prolonged far beyond the limits of the cell proto-
162 JOURNAL OF COMPARATIVE NEUROLOGY.
plasm; (3) in diseased and degenerate cells certain fibrillar
tracts, which pass in and out through the dendrites, may remain
intact and cannot be distinguished from normal fibrillae. Nuissv’s
figures are schematic and, as in the text, it is difficult to sepa-
rate fact from theory. His book, however, is of great value
in that it discloses the weak spots in the neurone theory and
shows that little or nothing is known of the extra-cellular ele-
ments found in the gray substance of the vertebrate nervous
system. Between the dendrites of the nerve cells and the
point at which the sensory axis cylinders lose their medullary
sheaths, there is practically a total blank in our present knowl-
edge of the nervous elements.
Nissi accepts as an established fact ApATuy’s hypothesis
that the nerve elements of invertebrates are connected by a
diffuse network in the neuropil. Not so the supporters of
the neurone theory, who are, however, divided in opinion. By
far the majority of them admit the existence of the neuro-
fibrillae, but deny that there is continuity between the neurones.
Prominent among this school are von LENHOSSEK (’g9Q), S.
MEYER ('99), and VAN GEHUCHTEN (:00). Other neurologists,
like WaLDEYER, HocuHE (’99) and VERWORN (:00), while ad-
mitting that fibrillar continuity may exist, hold, and we think
rightly, that the question of contact or continuity between the
neurones is a side issue. They doubt the existence of fibrillar
‘‘Gitterwerke,’’ however, and still maintain that the nervous
system is composed entirely of cell units.
Because of this doubt which still exists in the minds of
many neurologists, as to certain of ApATHy’s observations, the
writer has made a special study of the fibrillar structures found
in the neuropil of H/zxudo, the results of which are now in press.
The present paper furnishes further evidence as to the structure
of the neuropil and is supplemented by a more genera! study
of the neurofibrillae in the nerve elements of both A#udo and
Astacus. The research was begun at the Zoological Laboratory
in the University of Freiburg, Baden, and was completed at the
Strassburg Physiological Institute.
PRENTIsS, Neurofibrillar Structures. 163
Material and Methods.
The ventral ganglia of the leech (Hrudo medicinalis) and
the abdominal ganglia of the crayfish (Astacus fluviatilis) formed
the material on which most of my study was based. A part of
the Hzrudo material was treated as described in my former
paper (PRENTISS, : 03), the method being based on that of
BETHE (: 00a). Sections 10u thick, fixed in corrosive sublimate
were impregnated with ammonium molybdate solution (1:4000-
1:6000), differentiated about one minute in warm water (55°—
60° C) and then stained with an aqueous solution of toluidin
blue (1:3000). Inthe ganglion cells a pure fibrillar stain was
obtained by fixing ganglia for one hour in ether fumes, staining
zm toto with toluidin blue (1:3000) and fixing the stain ina 1%
solution of ammonium molybdate. The material was then
dehydrated, embedded in paraffin and sectioned in the usual
manner. This method is simple, but uncertain in its results. It
is a selective method, like methylen blue, and not all of the
fibrillae are demonstrated. Often, however, preparations were
obtained which showed the fibrillae with diagrammatic dis-
tinctness.
The preparations of Asz/acus material were all stained zntra
vitam with methylen blue. The fibrillae were differentiated by
leaving the ganglia 2-4 hours in normal salt solution ; the stain
was then fixed in ammonium picrate, which differentiates the
fibrillae more clearly than molybdate.
The Fibrillae in the Ganglhon Cells.
ApATHY describes two types of cells in the ventral ganglia
of Hirudo, distinguished from each other by their size and the
structure of the neurofibrillae. In the type to which the
smaller cells belong, one large fibril enters the cell and forms a
close meshwork of rather large fibrillae about the nucleus.
This is a motor or cellulifugal fibril according to APATHY; its
network about the nucleus is connected by radial fibrils with a
finer peripheral meshwork formed by smaller cellulipetal or
sensory fibrillae. In this manner he assumes that sensory and
motor elements are put into direct communication within the
164 JOURNAL OF COMPARATIVE NEUROLOGY.
cell itself. The cells of the second type are the largest in the
ganglion. Their fibrillae are of nearly equal size and forma
diffuse network throughout the plasma of the cell.
The difference in the fibrillar structures contained in these
two types of cells was very apparent in my own preparations.
A good example of the smaller type (the motor cells of
ApAtuy) is illustrated in Figure 14 (Plate VI). The inner
network about the nucleus was quite distinct in the preparation;
the fibrillae of which it is composed are somewhat larger and
therefore easier to trace than those in the periphery of the cell,
but preparations in which practically all of the fibrillae within
the cells are stained, show no such sharp distinction in the size
of the fibrillae as ApAtTuHy describes. Certain fibrils might
appear a little larger than others, but my preparations do not
warrant the assertion that the larger fibrillae a/ways form the
inner network, and the smaller the outer one, as APATHY main-
tains. Such large fibrillae as APATHy describes are often found,
however, in preparations in which only a portion of the fibrils
are stained. It may also be observed that the smaller the
number of the fibrillae to be seen in a cell process, the larger
those fibrillae usually are. It is well known that APATHY’s
gold chloride method demonstrates the fibrillae more com-
pletely in the cells than in their processes, and the large
‘‘motor” fibril which ApAtuy figures entering the cell and
forming the inner network, is, in every case, it may be noted,
the only fibril in the cell process. Several large fibrillae are often
formed in the cell processes by the cleaving together of the
primitive fibrils; if the impregnation of these were incomplete
so that only one fibril is visible, conditions would be produced
like those figured by ApATHy. We have such a case evidently
in Figure 3 (Plate V). One large fibril (4) is seen in the cell
process; this, however, divides into four smaller ones on enter-
ing the cell. It is obvious that but few of the fibrillae are
stained, which renders it especially easy to follow those which
are demonstrated. This cell belongs to the smaller type
described by ApAruy, but it may be observed that only one
branch (a) of the large fibril joins the inner network about the
PRENTISS, eurofibrillar Structures. 165
nucleus; the others take a more peripheral course, a fact
which is not in agreement with ApATuHy’s figures. In the same
section another cell of the same type was found (Figure 2,
Plate V). In this case, however, there are many fibrils of
nearly equal size in the cell process, although the networks
within the cell are incompietely stained. Neither in verte-
brates nor in crustacea do the neurofibrillae of the nerve cells
show any marked correlation in size and function.
In the giant cells of the leech there is no inner network
about the nucleus; the fibrillae are very numerous in the cell
process and divide to form a network of small irregular meshes
throughout the greater portion of the cell. A portion of such
a cell is shown in Figure 4 (Plate V) and gives some idea of the
great number of fibrillae which these giant cells contain.
The fibrillar structures in the ganglion cells of Astacus
and other decapod crustacea resemble somewhat those of the
larger type of cells in Azrudo. Such structures have been
described by BEeETHE (’98), and OwsIANNIKOW (: 00). BETHE
describes the fibrillae within the ganglion cells of Carcinus as of
nearly equal size, and forming a network of somewhat large
meshes throughout the plasma of the cell. OwsIANNIKOW
finds primitive fibrillae of two sizes in the nerve cells of
Astacus ; the smaller of these are found about the nucleus in
the form of a network; the larger fibrils occupy the peripheral
portion of the cell, and are the continuations of the fibrillae in
the cell process.
My preparations of Astacus showed no trace of a network
of fine fibrillae about the nucleus. The usual condition ob-
served is seen in Figure 15 (Plate VI). The fibrillae appear
relatively large and form a few large meshes in the peripheral
region of the cell. This figure corresponds to the descriptions
of BerHEe and resembles the only drawing which Owsranni-
KOW gives of the neurofibrillae in the cells; the figures of the
latter do not support the statements he makes in the text.
Fibrillar Structures tn the Cell Processes.
BETHE (’98) was the first to observe that in the crab a
166 JOURNAL OF COMPARATIVE NEUROLOGY.
nerve element may contain a greater number of neurofibrillae
than are found entering its cell, and to show that this was due
to the fact that many neurofibrillae may enter a neurone
through the collaterals, and pass out either through the
peripheral fiber or through other collaterals without entering
the cell proper. He regards such conditions as incompatible
with the neurone theory, because the fibrils which do not enter
the cell can not be integral parts of it, but must be the product
of some other cell or cells. The fibrillar structures in the
nerve elements of both the leech and the crayfish confirm
BETHE’S observations. From methylen blue preparations of
the abdominal ganglion of Aséacus, certain important facts may
be observed without the use of a high magnification. As
ApaATHY noted in the leech, many of the nerve elements are
paired: a large element in the right half of the ganglion has
its fellow, similar in size, form and extent, symmetrically placed
on the other side. More interesting still is the fact that doth of
these paired elements usually take the stain together, indicating the
existence of connection between them. In many of my
preparations of the second abdominal ganglion a pair of large
motor elements was often demonstrated. One of these from
the left side of the ganglion is shown in Figure 10 (Plate VI) ;
its fellow of the right side was its mirrored image even to the
number, position and extent of the collaterals. The collaterals
always branch to the same points in the neuropil, a fact directly
against the assumption that a diffuse fibrillar network exists.
For if this were the case, why should the processes of different
neurones always pass to the same spot in the neuropil, and
why should the nerve elements be arranged in bilateral sym-
metry? Such an arrangement would be useless if there were a
diffuse network of fibrillae in the neuropil, to put the dendrites
of all the nerve elements into general communication with one
another.
Figure 10 also illustrates a second point, which, as we shall
see, bears upon the fibrillar structures in the nerve elements.
The nerve fiber reaches its greatest size in the region desig-
nated by a, and this ts the point at which most of the collaterals
PRENTISS, Weurofibrillar Structures. 167
enter or leave the neurone; both the cell process (b) and the
peripheral fiber (c) ave considerably smaller than the region inter-
vening between them. ‘The greater size of this particular por-
tion of the elements is explained when the fibrillar structures are
studied under a higher magnification (Figure 11, Plate VI). It
may then be observed that the fibrillae are more numerous at this
point than in either the cell process proper, or in the peripheral
fiber. Many fibrillae of the large collaterals (d’) pass directly to
the periphery through the fiber c’; others, like fibril e, evidently
enter the element through one collateral and pass out through
another. The same condition was observed in the nerve
elements of the leech (Figure 2, Plate V). The figure is from
a preparation fixed in ether and stained with toluidin blue.
The plane of section was very favorable, showing the whole of
the cell process and short portions of the peripheral fiber and of
two collaterals in connection with the cell. Here again an
enlargement is found at the point where the large collaterals
branch off. As only fibrillar structures were stained, each
fibril could be traced with perfect distinctness; a large one (a’)
passes directly from a collateral at @ into the peripheral fiber 6
and is, therefore, independent of the ganglion cell.
In the large nerve elements of the leech a fibrillar net-
work is often found in that portion of the cell process from
which the collaterals branch. Two such cases have been
figured (Figures 5 and 7, Plate V). Figure 5 isa type of the
more simple connections which exist between the fibrillae in the
nerve elements. Three large parallel fibrillae (a, a’, a’) unite
at the point 0; atc, a single mesh is formed, from which are
given off several smaller fibrils that continue their parallel
courses in the process. In this, as in all well differentiated
molybdate preparations, the perifibrillar substance is not
stained, and the boundaries of the nerve elements are indicated
by the course of the fibrillae only.
The processes of the giant ganglion cells of the leech
often exhibit extremely complicated fibrillar networks soon
after they enter the neuropil (Figure 7, Plate V). In Figure 7
three large fibrillae from the longitudinal commissure unite
168 JournaL oF CompaRaTiveE NEUROLOGY.
with the process;.one of these fibrillae (d) joms a small fine-
meshed network at ¢; the fibrillae coming from the cell at 2 are
all put into communication with one another soon after they
enter the neuropil by the network at « Such connecting net-
works form direct paths for nervous impulses passing from one
merve element to another, and im entire independence of the
ganglion cells. These networks have been observed only m
the processes of the larger cells. Similar fibrillar structures
have been seen by Berse, whose observations have not as yet
been published The large single fibrillae which unite with the
fibrils of the process at right angles often divide forming
T-shaped branches. Im one case such a fibril was traced into
direct connection with the process of another nerve element
(Prentiss, : 03, Figure I9)-
Figure 1 (Plate V) shows an imteresting case of fibrillar
continuity within the process of a giant ganglion cell. The
process is so sectioned as to show only a portion of its cell, but
may be traced into the neuropil together with the three large
neurofibrillae which it contains. Immediately within the neu-
ropil, it is jommed- by two longitudinal fibrillae (2 and 4), which
branch and unite with two of the fibrillae from the cell; a cross
fibril, c, puts into direct connection with each other a and &,
which are fibrillae from the longitudinal commissures and are
evidently in connection with other ganglia, lying anterior and-
posterior. A nervous impulse, therefore, which was transmitted
from the ganglion next anterior to this one, or even from the
brain, would be conducted through fibril a, stimulate the nerve
element, and pass at once through cand 4 to the nerve elements
in the next posterior ganglion. I have never observed such
commissural fibers branching dichotomously like the dendrites
of motor elements, but they may constantly be seen in connec-
tion with cell processes, as in this case. The fibrillar structures
shown in Figure 1 were stained as opaquely as the fibers in
Gols! preparations, and since they were situated in a perfectly
clear space, the connections between the various fibrils were,
under a magnification of 2000 diameters, as distinct as a dia-
gram. The further continuations of the fibrillae in the cell
ee ee ee
———————E
Prentiss, Weurofiirillar Structures. 169
process were obscured by longitudinal fibrillae; they cross irreg-
ularly, but whetker a network was formed could not be deter-
mined with certainty.
In the crayfish was found one case of apparent connection
between the dendrite of a large motor neurone and a longitud-
inal connective fiber (Figure 12, Plate VI). To economize
space only a portion of the collateral 2 is shown im the figure,
but in the preparation this collateral was traced into connection
with a motor ganglion cell 46, one of the end branches of the
collateral 2, may be observed uniting with the small longitud-
inal fiber dat the pointc. This fiber contains several neuro
fibrillae, while 4, if not a single fibril, is composed of not more
than two. 4 does not branch on uniting with a, but can be
traced a short distance toward ¢, the anterior end of the longi-
tudinal connective. In the preparation, d was seen to extend
in both directions beyond the limits of the ganglion; naturally,
its cell was not demonstrated, but the fact that it is much larger
than 6 is sufficient ground for believing that all of the neuro
fibrillae which it contains do not come from the nerve element
a. The connection between 4 and dat the pomt ¢ seems as
Certain as if they were the branches of a single neurone.
Fibrillar Netwerks mm the Neuropil.
A considerable number of cases of fibrillar networks occur-
ring in the neuropil of Hzude have been described in another
paper (PRENTisS, : 03); two additional examples of the types
which occur most frequently in Hirvude, are figured here. Often
only two or three meshes are formed with which two or three
fibrillae are connected (Figure 6, Plate V). In other cases the
networks are much more complex, as seen in Figure 8. These
examples were found near the center of the neuropil, and there
is little likelihood of their being mistaken for networks m the
cell processes. In every instance they were of lmited extent,
and comparatively few fibrillae were connected with them.
In Astacus more extensive networks may be demonstrated
in the neuropil by means of methylen blue. Figures 9 and 13
are good examples of these fibrillar structures. The meshes
170 JOURNAL OF COMPARATIVE NEUROLOGY.
are larger than in the leech, and beads of perifibrillar substance
are scattered along the course of the fibrillae, often at their
points of union. These networks correspond more nearly to
those which ApATHy demonstrated in the leech with methylen
blue, but they are not so extensive.
My observations thus confirm the statements of APATHY
that fibrillar networks occur in both ganglion cells and neuropil.
The evidence, however, does not support his view that the
networks within the cells are formed by neurofibrillae which
differ from each other in both structure and function. This
conclusion is, moreover, in entire agreement with BETHE’s ex-
periment which proved that the cells are not the centers of ner-
vous activity as APATHY supposed. As to APATHY’S assump-
tion of a diffuse fibrillar network in the neuropil, there is no
evidence to show that such a condition exists. There are rather
numerous small networks, each limited to a definite region in
the neuropil, and putting comparatively few fibrillae into com-
munication with one another.
Fibrillar structures in my preparations of both H/zsudo and
Astacus, confirm BETHE’s statement that many neurofibrillae are
found in the nerve elements which are entirely independent of
the ganglion cells. In A/zvudo all the neurofibrillae of a nerve
fiber may be put into communication with one another by net-
works before they enter the cell.
These facts all point to the existence of fibrillar continuity
between the nerve elements; in both H/zvudo and Astacus appar-
ent cases of continuity between two neurones have been ob-
served. Great weight cannot be laid on only two observations
of such connection, for there is always the possible danger of
optical error in tracing such exceedingly small structures. But
the very existence of independent neurofibrillae in the nerve
elements and the presence of fibrillar networks in the neuropil
are incompatible with the idea that the nervous system is com-
posed of anatomically independent, cellular units. On the con-
trary such conditions can be explained only by assuming that
between the nerve elements fibrillar continuity exists.
The proof of such continuity does not, however, annihi-
PrENTIss, Neurofibrillar Structures. 17E
late the neurone theory ; it simply modifies it. There is as yet
_no direct evidence to prove that these fibrillar networks in the
neuropil may not be formed by the union of fibrils, each of
which was developed in a distinct cell. At present we know
nothing of the origin of the neurofibrillae in the central ner-
vous system, and, therefore, the presence of independent fibril-
lae in the nerve elements does not necessitate the abandonment
of the neurone idea; for such fibrillae, which do not enter the
cell, may be differentiated in the plasma of the cell processes,
and be as much a part of the cell as the processes themselves.
The fundamental experiment of Berne (’98) while of great
value to neurology, does not in itself prove the neurone theory
false ; it merely shows that the nerve elements may function for
some time without their cells; that the cells are not the batteries.
which generate the nervous current, as was formerly supposed.
An unprejudiced thinker can but agree with VERWORN
(: 00) when he says that: ‘‘der Begriff des Neurons und damit
auch die Neuronenlehre erst dann und nur dann erschittert
ware, wenn es gelungen, zu zeigen, dass das, was wir als cellu-
lare Einheit betrachten, in Wirklichkeit aus mehreren Zellen
besteht.’”’ The only important evidence which at present goes
to show that the ‘‘cellulare Einheit’’ of the nervous system
‘‘aus mehreren Zellen besteht,’’ consists of BETHE’s preliminary
statements of his researches in the histogenesis and pathology
of the nerve elements. Before passing judgment on BETHE’s
work we must wait until a full account of it appears. If, as is
probable, the results of his work prove beyond a doubt that the
supposed cell individual is the product of many cells, the neu-
rone theory will be untenable. If not, the neurone theory will
still remain—a ¢heory; for our present methods have thus far
failed to prove ‘‘beyond a doubt,” that the nervous system is
made up of cell units, and nothing but cell units.
172 JOURNAL OF COMPARATIVE NEUROLOGY.
LITERATURE.
APATHY, S.
’97. Das leitende Element des Nervensystems und seine topographis-
chen Beziehungen zu den Zellen. Mitth. d. zooloy. Station z. Neapel.
Bd. 12, p. 495-748, Taf. 23-32.
BALFour, F. M. :
*76. On the Development of the Spinal Nerves in Elasmobranch Fishes.
Phil. Trans. Roy. Soc. London, Vol. 166, p. 175-199, pls. 16-18.
BETHE, A.
’98. Das Nervensystem von Carcinus maenas. Arch. f. mikr. Anat.
Bd. 51, p. 382-452, Taf. 16-17.
BETHE, A.
98a. Ueber die Primitivfibrillen in den Ganglienzellen von Menschen und
andern Wirbelthieren. Morph. Arbetten, Bd. 8, p. 95-116, Taf. 9-10.
BETHE, A.
:00. Ueber die Neurofibrillen in den ganglienzellen von Wirbelthieren
und ihre Beziehungen zu den Golginetzen. Avch. f. mtkr. Anat.
Bd. 55, p- 513-558, Taf. 29-31.
BETHE, A.
:00a. Das Molybdanverfahren zur Darstellung der Neurofibrillen
und Golginetze im Centralnervensystem. Zettschr. f. wiss. Mikrosk.
deity pape 13-35).
BETHE, A.
:02. Ueber die Regeneration peripherischer Nerven. Arch. f. Psychiatr.
Bd. 34, p. 1066-1073.
DoHRN, A.
’o1. Nervenfaser und Ganglienzelle. Histogenetische Untersuchungen.
Mitth. d. zoolog. Station z. Neapel. Bd. 10, p. 225-341, Taf. 16-22.
FoREL, A. ;
86. Einige himnanatomische Betrachtungen und Ergebnisse. Arch. /.
Psychiatr. Bd. 18, 37 pp.
GEHUCHTEN, A. VAN
:00. Anatomie du systéme nerveux de l’homme. Legons professées a
Université de Louvain, 3me édition, Louvain, 2 vols., 1106 pp.,
702 figs.
GUDDEN, B. VON
’*89. Gesammelte und hinterlassene Abhandlungen. Herausgegeben von
H. Grashey. Wiesbaden, 6 + 221 pp., 41 Taf.
HARRISON, R. G.
:o1. Ueber die Histogenese des peripheren Nervensystems bei Salmo
salar. Arch. f. mtkr. Anat. Bd. 57, p. 353-444, 7 Fig., Tafel 18-20.
His, W.
’89. Die Neuroblasten und deren Entstehung im embryonalen Mark.
Arch. f. Anat. u. Physiol. anat. Abtheil. p. 249-300, Taf. 16-19.
His, W.
’90. Histogenese und Zusammenlaug der Nervenelemente. Arch. f-
Anat. u. Physiol. anat. Abthetl., Suppl. Bd., p. 97-117, 30 Fig.
Prentiss, Meurofibrillar Structures. 173
HocuHeE, A.
’99. Der gegenwiartige Stand der Neuronenlehre. eurol. Centraldl.
18 Jahrg., 37 pp-
LENHOSSEK, M. VON.:
99. Kritisches Referat iiber die Arbeit A. BETHE’s: Die anatomischen
Elemente des Nervensystems und ihre physiologische Bedeutung.
Neurol. Centraibl. 18 Jahrg., p. 242-246, 301-308.
MEYER, S.
99. Ueber centrale Neuritenendigungen. Arch. f. mikr. Anat. Bd. 54,
p. 296-311, Taf. 17.
MONCKEBERG, G., und BETHE, A.
?99. Die Degeneration der markhaltigen Nervenfasern der Wirbelthiere
unter hauptsichlicher Berticksichtigung des Verhaltnisses der Primi-
tivfibrillen. Arch. f. mikr. Anat. Bd. 54, p. 135-189, Taf. 8-9.
NIss.L, F.
:03. Die Neuronenlehre und ihre Anhaénger—ein Beitrag zur Lésung
des Problems der Beziehungen zwischen Nervenzelle, Faser und
Grau. Jena. vi- 478 pp., 2 Taf.
OWSIANNIKOw, P.
99. Ueber die Nervenelemente und das Nervensystem des Flusskrebses,
Astacus fluviatilis. Mém. Acad, St. Petersburg. (8) Tome to,
30 pp., I Tafel.
PRENTIss, C. W.
:03. Ueber die Fibrillengitter in dem Neuropil des Hirudo und Astacus
und ihre Beziehung zu den sogenannten Neuronen. Archiv f. mtkr.
Anat. Bd. 62, pp. 592-606, Taf. 26.
VERWORN, M. ‘
:00. Das Neuronin Anatomie und Physiologie. /ena. 54 pp., 22 Fig.
WALDEYER, W.
’91. Ueber einige neue Forschungen im Gebiet der Anatomie des Ner-
vensystems. Deutsche med. Wochenschrift. No. 44-50.
EXPLANATION OF PLATES.
The fibrillar structures which are described in the text are repro -
duced by dark lines, as they appeared in the preparations; the out-
lines of the less important fibrils were drawn much lighter, for the
sake of clearness. The Figures were projected and outlined with a
Leitz camera lucida (ABBE model). With the exception of Figure ro
the drawings were made with the use of a LeIrz 1-16 oil immersion
objective, and a No. 4 ocular. With a tube length of 160 mm. and a
projection distance of 320 mm. this system gives a magnification of
approximately 2000 diameters. Figure 10 is magnified 160 diameters
by means of a LeITz objective No. 3, and ocular No. 4.
174 JOURNAL OF COMPARATIVE NEUROLOGY.
PLATE V.
All the figures are from toluidin blue preparations of Azrudo. Figures 2
and 3 are from material fixed in ether.
Fig. r. An oblique section through a large ganglion cell and a portion of
the neuropil, showing the connection between the fibrillae in the cell process.
The greater part of the cell is cut away. a, 4,two fibrillae from the longi-
tudinal commissures; ¢c,a short fibril connecting @ and 4; d, the bounding
membrane between neuropil and ganglion cells.
Fig 2. A-small ganglion cell with its process, portions of the peripheral
fiber (4), and of two collaterals. Part of the peripheral fibrillar network is seen
in the cell; in that region of the element, from which the collaterals branch
off, a large fibril (a) may be traced from one of the collaterals into 4, the
peripheral fiber, where it is designated by a’.
Fig. 3. A ganglion cell of medium size from the same section as Figure
2. Only the neurofibrillae and the nucleus were visible in the preparation. 4,
the single large fibril in the cell process ; a, one of its branches which unites
with the network about the nucleus.
Fig. g. A section through the peripheral portion of a giant ganglion cell,
showing the close-meshed fibrillar network characteristic of the larger cells of
Hirudo.
Fig. 5. Ashort portion of a cell process showing the connection between
its neurofibrillae ; a, a’, a’’, three fibrillae which in passing from the cell into
the neuropil, unite at 6; atc asingle mesh is formed, from which numerous
small fibrillae continue their course in the process. The perifibrillar substance
is not stained.
Fig. 6. One of the simpler cases of fibrillar networks found in the
neuropil of Azrudo. Only two meshes are formed, which are in connection
with three fibrillae.
Fig. 7. An example of the fibrillar networks in the processes of large
nerve elements. a, proximal end of the cell process; 4, bounding membrane
of the neuropil; ¢, the network by which all of the fibrillae are connected
together ; d, a large neurofibril which unites at e with a smaller network.
Fig. 8. A fibrillar network of four meshes found near the center of the
neuropil. a-/, fibrillae uniting with the network.
PLATE VI.
Figure 14 is a toluidin blue preparation from Airudo. All the other fig-
ures are methylen blue preparations from Ast¢acus material.
Fig. 9. Anetwork of neurofibrillae from the third abdominal ganglion
of Astacus. At the point a the network is apparently connected with the longi-
tudinal nerve fiber 4; c, beads of perifibrillar substance, characteristic of
methylen blue preparations.
Fig. ro.
PLATE Vil.
Ranson, f2bers in Lesions of the Brain. 207
made onasmall scale because the scar was too wide to be included with
the surrounding tissue in a high power tracing. The alveus (a) is normal. The
corpus callosum (¢.c.) is unstained, with the exception of a few fibers. The
arrow indicates the path of the knife and ‘‘f”’ designates a fiber apparently
crossing the scar.
fig. 8. Camera lucida tracing of a small area of scar in another section
from the same brain (Rat No. 4) as that represented In Fig. 4.
fig. 9. Drawing of the aggregation of fibers in the scar in the ventral
part of the cortex (Rat No. 2) shown in Fig. 2. Notice the masses of blood
pigment (4) along the line of the wound indicated by the arrow. Many fibers
run downward along the scar, some of which cross the line of the incision at *f’’.
fig. 10. Drawing from a frontal section of the left cerebral hemisphere
of arat operated on at the age of 4 days and killed 32 days later. The cortex
was fixed in VAN GEHUCHTEN’S solution, imbedded in paraffin, cut in sections
6 thick, and stained in erythrosin and toluidin blue. The path of the knife
is indicated by ‘‘c’’. Notice the absence of connective tissue cells, and the
presence of nerve cells bordering directly on the line of the incision.
ON THE DENSITY OF THE CUTANEOUS INNER-
VATION IN MAN.
By CuHaArRLes E. INGBERT.
(Yrom the Neurological Laboratory of the University of Chicago.)
I. INTRODUCTION.
Il. THeE RELATION OF THE CUTANEOUS AND THE MUSCULAR NERVE
FIBERS OF THE DORSAL ROOTS OF THE SPINAL NERVES OF MAN.
rT. Lstimate Based on Stilling’s Results.
Estimate Based on Votschvillo’s Results.
3. Estimate Based on the Author’s Enumeration.
4. Comparison and Discussion.
ly
III. DETERMINATION OF THE AREA OF THE DERMAL SURFACE OF THE
HUMAN Bopy.
I. Krause’s Determination.
2. Funke’s Determination.
3. Fubini and Roncht’s Determination.
4. Mech’s Determination.
5. Summary of Determinations.
IV. THE INNERVATION OF THE DERMAL SURFACE OF THE HUMAN Bopy.
1. Donaldson's Estimate.
2. Votschvillo’s Estimate.
3. Author's Estimate.
4. Comparison and Discussion.
V. THE BEARING OF THE AUTHOR’S ESTIMATE OF THE INNERVATION OF
THE DERMAL SURFACE ON THE THEORY OF THE SPECIFIC ENERGIES
oF NERVES.
VI. SUMMARY.
VII. BIBLIOGRAPHY,
I. INTRODUCTION.
It was, at first, the author’s intention to publish this dis-
cussion as a part of his more extended paper on the ‘‘ Enumer-
ation of the Medullated Nerve Fibers in the Dorsal Roots of
the Spinal Nerves of Man.” This, however, was found im-
210 JoURNAL OF COMPARATIVE NEUROLOGY.
practicable owing to the accumulating evidence that STILLING’s
estimate of the number of nerve fibers in the ventral roots of
the spinal nerves, which was used in calculating the number of
cutaneous fibers in the dorsal roots, was not sufficiently accu-
rate for our purpose. The data necessary for this calculation
are the enumerations of the nerve fibers in both the dorsal and
the ventral roots. The former the author has published (1903),
as already mentioned. It was therefore necessary to make a
similar enumeration of the fibers in the ventral roots. This
being now completed, the estimation of the density of the
cutaneous innervation in man is possible and is here pre-
sented.
II. THE RELATION OF THE CUTANEOUS AND THE MUSCULAR
NERVE FIBERS OF THE DorsSAL ROOTS OF THE SPINAL
NERVES oF Man.
Having determined the number of nerve fibers in the dor-
sal roots of the left side in man (INGBERT, 1903), our next step
is to inquire how many of these afferent fibers innervate mus-
cles and other deep tissues, and how many the skin.
According to SHERRINGTON’s (1894-95) observations on the
cat, the afferent nerve fibers ina muscular nerve constitute two-
fifths and the efferent three-fifths of its fibers. Or in other
words, in a muscular nerve the afferent nerve fibers are to the
efferent as 2 to 3. If we assume that this relation is typical of
all muscular nerves, and if we assume that the same relation is
true for man, then to the total number of efferent muscular
nerve fibers, i. e., to the total number of nerve fibers in the
ventral roots, there must be added two-thirds as many afferent
fibers in order to make up the muscular nerves. In this calcu-
lation we have neglected the recurrent nerve fibers in the ven-
tral roots because, even if present in man, their number must
be very small. The fibers of the ventral roots passing into the
white ram communicantes have also been neglected, because
their number is not great and because we may assume without
any serious error that the relation between the afferent and
INGBERT, Cutaneous Innervation in Man. 211
efferent fibers in them does not differ sufficiently from that in
other peripheral trunks to modify our result.
I. Estimate Based on Stilling’s Results. According to
STILLING (1859) there are in man, in round numbers, 500,000
nerve fibers in the dorsal roots of the spinal nerves of both
sides, and 300,000 in the ventral. We therefore take from
500,000 fibers a number equal to two-thirds of 300,000, or
200,000 fibers, in order to add these to the efferent fibers in the
muscular nerves. This leaves 300,000 or 60% of the nerve
fibers of the dorsal roots to innervate the dermal surface of the
body. If these data were correct, as unfortunately they are
not, we could conclude that about 60% of the afferent fibers in
the dorsal roots of man are cutaneous, i. e., go to innervate the
dermal surface of the body, and about 40% go to the muscles.
In the 60% credited to the skin there are included the fibers
which pass to the viscera by the vam communicantes and recur-
rent nerves, if any, but so far as we know, the number of these
is small, and, for the present purpose, may be neglected.
2. Estimate Based on Voischvillo’s Results. Another
calculation on the relation of the cutaneous and the muscular
nerve fibers in the dorsal roots of man can be made from the
results of VoIscHvILLo (1883) and those by myself. Vorscu-
VILLO sectioned the peripheral nerves in man at the places
where they divide into cutaneous and muscular branches. The
material used by him was hardened by 1% osmic acid and pre-
served in g5% alcohol. The areas of the cross-sections of the
nerves (of which I can find no record) were obtained by two
methods, (1) by dividing the volume (determined by weighing)
of a piece of nerve by its length, (2) by projections of the
cross-section made by means of a camera lucida.
In estimating the number of fibers in a peripheral nerve
VoIscHVILLO counted all the nerve fibers of the section of the
nerve that could be seen within a certain number of the squares
of the ocular micrometer, and from this result he estimated the
number in the entire cross-section.
VOISCHVILLO’S average for the number of nerve fibers in
the cutaneous nerves derived from the brachial plexus of one
212 JOURNAL OF COMPARATIVE NEUROLOGY.
side is 119,337. Since, according to my count, the dorsal
roots (C. V.—Th. I) which help form the brachial plexus, con-
tain 193,095 fibers, the cutaneous fibers in these roots as
determined by VoIscHvILLO amount to 61.7%. In consider-
ing the dorsal roots C. V.—Th. I as the roots giving rise to
the afferent fibers of the brachial plexus I have made use of P.
EIsLer’s drawings (Rauber 1893). According to these draw-
ings the brachial plexus also receives a branch from the roots of
C. IV and another from the root Th. II (N. intercostobrach-
jalis). These two sources of gain would make Volscu-
VILLO’s results too large were it not for the fact that he omitted
in his estimate the cutaneous fibers given off by root Th. I in
the N. intercostalis primus, as well as the few cutaneous fibers
in the rami dorsales of C. V to Th. I. These two factors no
doubt counterbalance each other to a great extent and thus
justify us in our calculation
Again, by adding VolscHviILLo’s averages for the number
of nerve fibers in the cutaneous nerves derived from the
lumbosacral plexus of one side, I find them to amount to 154,-
459 fibers (his own total, by another method which I cannot
understand, is 82,167). According to my count, the dorsal
roots (L. II—S. III) which help form this plexus contain 228,-
117 nerve fibers. In other words, according to VoISCHVILLO’S
results 67.7% of the nerve fibers in these dorsal roots are
cutaneous.
I have omitted the root L. I in this calculation because
VoISCHVILLO made no estimate of the peripheral nerves de-
rived from this root. The roots S. IV. S. V, and Coc. I, have
also been omitted for the same reason. The gain from the root
of L. I is, no doubt, counterbalanced to some extent by losses
in branches passing into N. pudendus and N. clunium medius
which he omitted.
3. Estimate Based on the Author's Enumeration, Accord-
ing to the author’s enumeration (INGBERT, 1903) the left dorsal
roots of the spinal nerves of a large man contain 653,627
medullated nerve fibers. Since the publication of this report
the author has made an enumeration of the medullated nerve
INGBERT, Cutaneous Innervation in Man. 2h3
fibers in the ventral roots of the spinal nerves of the same cord.
This latter enumeration gives 203,700 medullated nerve fibers
on one, the left, side of the body, or about 407,400 on both
sides. (The report on this investigation will be published in
the near future. )
As already mentioned, according to SHERRINGTON
(1894-95) there are two-thirds as many afferent nerve fibers in
a muscular nerve (a mixed branch to a muscle) as there are
efferent fibers. We must, therefore, take two-thirds of 203,-
700 or 135,800 from 653,627 and add them to the efferent
fibers in order to represent all the muscular nerves. This
leaves 517,827 nerve fibers to innervate the dermal surface of
the body; or, in other words, 79.22% of the fibers in the dor-
sal roots to innervate the dermal surface and 20.78% to supply
muscles and other deep tissues with afferent nerves.
4. Comparison and Discussion. For comparison let us
now repeat these estimates of the number of cutaneous fibers
the in the dorsal roots:
I. Estimate Based on STILLING’s Results 60.00%
2. Estimate Based on VOISCHVILLO’s Results
a. Brachial plexus 61.70%
b. Lumbar plexus 67.70%
3. Estimate Based on Author’s Results 79.22%
The low figure obtained from STILLING’s data is doubtless
due to SriLiine’s failure to include the fibers the diameter of
which is less than 74, as the author has already demonstrated
(INGBERT, 1903, p. 68), together with the fact that these fibers
of asmall diameter are more abundant in the dorsal roots, a
point to be discussed in another paper. We consequently con-
clude that his figure for the number of fibers in the dorsal roots
is more below the true one than his figure for those of the ven-
tral roots. This becomes apparent on a comparison of the
ratio between the fibers in the two roots.
Ventral Roots. Dorsal Roots.
STILLING a 1.66
INGBERT I 3.20
The cause of the low figure obtained from VoIscHVILLo’s
214 JOURNAL OF COMPARATIVE NEUROLOGY.
results is not so easily found; but is probably partly due to the
fact that his results represent an estimate and not an enumera-
tion. It is also highly probable that the osmic acid did not in
the material used by him bring out all the smallest fibers suffi-
ciently well to be included. |
In order to determine the value of the calculations for the
innervation of the skin about to be given, it will be well to
consider in detail the methods by which the data for these
calculations were obtained.
III. DETERMINATION OF THE AREA OF THE DERMAL SuR-
FACE OF THE Human Bopy.
I. Krause’s Determination. Krause (1844) determined
the dermal surface of the body to be 1,584,300 mm*. or about
15 square feet. I can find no record of his method, nor any
description of the subject used. :
2. unke’s Determination. In making his determination
of the area of the dermal surface FUNKE (1858) covered the
half of a cadaver with gummed paper cut into one inch squares,
as well as into smaller pieces, the values of which were deter-
mined beforehand. In so doing care was exercised to cover
every part of the skin, to allow no overlapping of the paper,
and to guard against the folding of either the paper or the skin.
The results obtained he considers accurate within a square inch.
He thus determined the areas separately for each part of the
body, and gives as the entire area 1,651,700 mm”.
3. Fubinit and Ronchi’s Determination. These investiga-
tors (1881) divided the surface of the body into its anatomical
regions and marked these by sharp lines. These regions were
‘then divided into such geometrical figures as could easily be
measured. For the head a craniometer was employed. The
measurements were made on the cadaver of a man 1.62 meters
in height, and 50 kg. in weight. They determined the areas
for the different parts separately and found the entire area to be
1,606,685 mm’.
4. Meeh’s Deiermination. Mee (1879) combined in his
method several valuable features. "On large even surfaces he
INGBERT, Cutaneous Innervation in Man. 215
marked the regions by red lines and traced these on transparent
paper. These areas were then measured from the paper.
Around the fingers he wound strips of paper of a uniform
width. Other uneven surfaces he covered with gummed paper.
Although Meru measured several subjects, the results for a
thirty-six years old man, corpulent, 171 cm. in height, and
body-weight 78.2 kg., only are given.
Area for the right side of the body:
Head 80,380 mm?.
Neck 45,060 ‘
Trunk 294,160 *
Upper arm 785150)
Fore-arm 67,860 ‘
Hand 535050)
Thigh DOW 250) meine
Shank 1265920) 5
Foot 66,930 *
Pelvic region 106,580 ‘*
I.121,740 mm?.
Both sides (his own figure) 2,243,490 mm?.
By pelvic region MrEH means the dermal surface of the
hips, i. e., the area between a line running along the crest of
the pelvis and one transversely around the thigh about on a
level with the ‘uberculum pubicum. ‘This region is innervated
by lumbar and sacral nerves and is included in the area for the
the entire leg.
MeEeEn’s line between the neck region and the trunk region
runs from the top of the acromion process along the clavicle on
the ventral surface of the body and on the dorsal surface to
about the level of the spine of the seventh cervical vertebra.
Since, however, the nn. supraclaviculares innervate a portion of
the skin below the clavicle, it is probable that his area for the
neck region is a trifle too small for the skin innervated by the
cutaneous nerve fibers in the dorsal spinal roots C. I-IV.
216 JOURNAL OF COMPARATIVE NEUROLOGY.
5. Summary of Determinations of the Area of the Entire
Dermal Surface of the Human Body of Adult Men.
Height Body wt. Area of
imC€ms) ain) Ke: Dermal sur-
Age face in mm?. Observer.
17 years, well-built 169 55:5 1,920,550 MEEH (1879)
20 years, 170 59-5 1,869,530 5G GC
26 years, 162 62.3 1,895,960 66 oe
36 years, corpulent 171 78.3 2,243,490 a ee
36 years, emaciated 158 50.0 1,758,740 os ue
45 years, 160 51.8 1,799,350 3 a
66 years, 172 65.5 2,028,150 Ce uC
(Not given) ? ? 1,584,300 KRAUSE (1844)
(Not given) y ? 1,651,700 FUNKE (1858)
(Not given) 162 50.0 1,606,685 FUBINI and BoONCHI (1881)
Having now data for the number of cutaneous nerve
fibers in the dorsal roots of the spinal nerves of man, and for
the area of the dermal surface of the body, we are enabled to
make calculations as to the innervation of the skin, not only
for the body as a whole, but also for some of its principal parts.
IV. THe INNERVATION OF THE DERMAL SURFACE OF THE
Human Bopy.
Z. Donaldson's Estimate. DoNALvson (1901) for the
area of the dermal surface made use of the results obtained by
Meen for a man weighing 136 lbs.—1,g00,000 mm’. For the
number of cutaneous nerve fibers in the dorsal roots he took
60% of STILL1NG’s estimate of 500,000, —300,000. According
to this calculation, every cutaneous nerve fiber in the dorsal
roots innervates, on the average, 6.3 mm” of the dermal
surface.
2. Vortschvillo’s Estimate. This investigator (1883) out-
lined upon a cadaver the skin areas of the peripheral nerves as
given by HENLE (1879).
These outlines were traced on transparent paper, and the
area of these outlines determined by placing this transparent
paper upon a sheet of paper ruled in sq. cm. and sq. mm.
According to his summary there are I19,337 cutaneous nerve
fibers to innervate the 130,084 mm’. of dermal surface of the
upper limb, or on the average one nerve fiber to every
1.1 mm’. of skin; and 82,167 cutaneous nerve fibers (154,459
INGBERT, Cutaneous Innervation in Man. 217
according to my addition of his results) to innervate the
303,566 mm?. of the dermal surface of the lower limb, or on
the average one cutaneous nerve fiber for every 3.7 mm”. of
skin. If my addition of his results be correct this will give
one cutaneous nerve fiber to every I.g mm?. of skin.
3. Author's Estimate. Since the cadaver from which the
spinal roots used in my count of the nerve fibers was that of
a man weighing 180 lbs. or 81.6 kg., I have made use of
MEEn’s data, as already given, for the heaviest man measured
by him, one weighing 78.3 kg.
A. Body as a whole:
Area of one side of body, 1,121,740 mm?.
Deduction for skin of the head innervated by the
cerebral nerves, (24 of 80,360) 53,573 mm?.
Corrected area, 1,068,167 mm?.
Number of cutaneous nerve fibers (79.22% of 653,627) 517,827
1,068,167+517,827= 2.05 mm?,
Hence, every cutaneous nerve fiber in the dorsal roots
innervates on the average 2.05 mm”. of the dermal surface.
Be) Armi:
Area of the arm, 199,860 mm?.
Number of cutaneous nerve fibers in dorsal roots,
C. V.—Th. I (79.22% of 193,095) 152,970
199,860+152,970—= 1.30 mm?,
Hence, every cutaneous nerve fiber in the roots C. V—
Th. I innervates, on the average, 1.30 mm? of the dermal
surface of the arm.
C. Head and Neck:
Areaof one side of neck, 45,060 mm?.
Area of one-third of head on one side, 26,786 Ԥ
Total, 72,446 mm!.
Number of cutaneous nerve fibers in dorsal roots of
C. I.—IV (79.22% of 84,404) 66,865
72,453+66,865= 1.08 mm?,
Hence, every cutaneous nerve fiber in the dorsal roots of
C. I—IV innervates, on the average, 1.08 mm’. of the dermal
surface of the neck, and that part of the head not innervated
by cerebral nerves.
D. Leg:
Area of surface of one leg, 501,680 mm?.
Number of cutaneous nerve fibers in the dorsal roots
L. I—Coc. I (79.22% of 258,502) 204,785
501, 680+ 204,785= 2.45 mm?.
218 JOURNAL OF COMPARATIVE NEUROLOGY.
Hence, every cutaneous nerve fiber in the dorsal roots
L. I—Coc. I innervates, on the average, 2.45 mm”. of the
dermal surface of the leg.
ES) Drunk:
Area of surface, one side, 294,160 mm?.
Number of cutaneous fibers in the dorsal roots of Th.
II-XII (79-22% of 117,626) 93,182
294, 160+-93,183= 3.15 mm?.
Hence, every cutaneous nerve fiber in the dorsal roots
Th. II-XII innervates, on the average, 3.15 mm”. of the
dermal surface of the trunk.
For the purpose of comparison these results may be sum-
marized as follows:
Average area of dermal surface innervated by one afferent fiber.
Body as a whole, 2.05 mm?.
Head and Neck, 1.08 ‘<<
Arm, eROnee:
Leg, Pegs, 0
Trunk, SUG es
4. Comparison and Discussion. As already shown,
DoNALDSON’s estimate of the innervation of the skin is, on
the average, one cutaneous fiber to every 6.3 mm”. of the
surface of the skin. Since this estimate is based on Stit-
LING’s determination of the number of nerve fibers in the
dorsal spinal roots, it is evident that the source of the differ-
ence between this estimate on innervation and my own is
the fact that STILLING’s results are only 40% of mine. To
show that DoNALDsON anticipated that STILLING’s results would
prove less than they should be, I quote his statement concern-
ing them: ‘‘It seems probable that both these estimates (i. e.,
for the fibers in the dorsal and ventral roots) were too low”
(DoNALDSON 1901).
The difference between VoISCHVILLO’s results and my own
is due chiefly to the fact that he used 130,084 mm’. and
303,566 mm’. respectively for the area of the dermal surface
of arm and leg, while I used for the same 199,860 mm’. and
501,680 mm’. In other words, using equal values for the area
INGBERT, Cutaneous Innervation in Man. 219
of the dermal surface, the estimates for the cutaneous innerva-
tion by VOoISCHVILLO will be very nearly the same as that ob-
tained by myself.
A study of the following tables makes this apparent :
Estimate by VOISCHVILLO.
Area of Dermal Surface
Dermal area Number of innervated by one cuta-
Part in sq. mm. Nerve Fibers neous nerve fiber.
Arm 130,084 119,337 I.1 mm?
Leg 303,566 154,459 1.9 mm?
Estimate by Author.
Area of Dermal Surface
Dermal area Number of innervated by one cuta-
Part in sq. mm. Nerve Fibers neous nerve fiber.
Arm 199,860 152,970 1.30 mm?
Leg 501,680 204,785 2.45 mm?
Estimate based on Number of Fibers used by VoiscuviLLo and area
of dermal surface used by Author.
Area of Dermal Surface
Dermal area Number of innervated by one cuta-
Part in sq. mm. Nerve Fibers neous nerve fiber.
Arm 199,860 119,337 1.42 mm?
Leg 501,680 154,459 2.25 mm?
One factor, however, is not considered in this comparison,
viz: VOISCHVILLO’s observations being taken at the periphery of
the body would tend to give him a high number of fibers
owing to their branching. But as his estimate onthe innervation
(using the same dermal areas) is very nearly the same as
that obtained by myself, it is likely that his estimate of the num-
ber of cutaneous fibers is too low. This agrees with the fact that
the calculation of the cutaneous nerve fibers in the dorsal roots
of the spinal nerves based on VoIscHVILLo’s data, gives only
60 to 67% while that based on my own data gives 79.22%.
Concerning my own estimate for the innervation of the
skin, it may be remarked that it is probable that in different
persons the skin areas differ more than the numbers of nerve
fibers in the dorsal roots of the spinal nerves, and since I have
made use of the spinal roots of a large man and the largest
area of the dermal surface on record, it is probable that if a
220 JOURNAL OF COMPARATIVE NEUROLOGY.
smaller subject were used for the determination of both the
number of fibers and area of skin, the area of skin for each
cutaneous nerve would be somewhat smaller.
V. THE BEARING OF THE AUTHOR’S ESTIMATE OF THE INNERVA-
TION OF THE DERMAL SURFACE ON THE THEORY OF THE SPE-
CIFIC ENERGIES OF NERVES.
It might be of interest to consider the bearing this esti-
mate of the innervation of the skin has upon different theories
as to the number of classes of nerve fibers that mediate the
dermal sensations. If we assume with WEBER (1846) that
impulses giving rise to sensations of heat, cold, pressure, and
pain, pass over the same afferent cutaneous nerve fiber, then
the above calculations will hold true, viz., one cutaneous nerve
fiber, on the.average, innervates 2.05 mm’. of the dermal
surface, giving all these forms of sensation to that area. If, on
the other hand, we assume with Foster (1891) that there are
four classes of afferent cutaneous nerve fibers, then this esti-
mate will have to be so changed that one cutaneous nerve fiber
of each class will innervate, on the average, 42.05 mm7?., or
8.2 mm’. of the dermal surface. To specify more in detail,
one cutaneous nerve fiber of each class will have to innervate
4X1.3 mm’*., or 5.2 mm”. of the dermal surface of the arm; and
4X3.15 mm”, or 12.6 mm’. of that of thetrunk. If this theory
be true, then a histological examination of the nerve termina-
tions in the skin ought to show each cutaneous fiber of the dor-
sal roots to innervate, on the average, an area of the skin of
the trunk equal to 12.6 mm*. However, until we know the
amount of branching of these fibers, not only in the skin but
also in the peripheral trunks, we are unable to judge whether
or not it is possible for one nerve fiber to innervate so large an
area of the skin.
VI. Summary.
1. According to the estimate here made, about 79% of
the medullated nerve fibers in the dorsal roots of the spinal
nerves of both sides, or 1,032,730 fibers, go to innervate the
dermal surface and about 21%, or 274,521, are afferent fibers
INGBERT, Cutaneous Innervation in Man. 221
distributed to muscles and deep tissues. The afferent fibers of
spinal ganglion origin passing in the vam communicantcs are not
separately considered in this estimate, but for the moment are
classed with those passing to the skin.
2. According to my estimate (using the skin areas fora
large man), one cutaneous nerve fiber in the dorsal spinal roots
innervates, on the average, 1.08 mm’. of the skin of the head
and neck, 1.30 mm’. of the skin of the arm, 2.05 mm” of
the skin of the entire body, 2.45 mm”. of the skin of the leg,
and 3.15 mm. of the skin of the trunk; and for each addi-
tional class of nerve fibers assumed we must increase the area
proportionately.
3. If we assume, with Fosrer, four classes of cutaneous
nerve fibers, then each fiber will have to innervate, on the
average, 4.32 mm’. of the dermal surface of the head and neck,
and 12.6 mm’. of the dermal surface of the trunk.
4. If there be four classes of afferent nerve fibers in the
dorsal roots of the spinal nerves of man, then a histological
examination of the nerve terminations in the skin ought to
show each cutaneous nerve fiber to innervate, on the average,
areas of skin as large as given above.
VII. BIBLIOGRAPHY.
Donaldson, H. H.
1901. Am. Text-Book of Physiol.. Phzladelphia, and London, Vol. Il,
p. 230,
Foster, M.
1891. Physiology, Pt. 1V, London, ps 281.
Fubini, S. and Ronchi, J.
1881. Untersuch. z. Naturl. d. Mensch, u. d. Thiere. XII, p, 26.
Funke, O. F.
1858. Untersuch. z. Naturl. d. Mensch, u. d. Thiere, IV, p. 36.
Henle, J.
1879. Handb. der Systemat. Anatomie. Braunschweig. Bd. \II, Abthe
I, pp. 554 and 594.
Ingbert, C. E.
1903. Journ, Comp. Neur., Granville, Vol. XIII, p. 53.
222 JOURNAL OF COMPARATIVE NEUROLOGY.
Krause, C. F.
1844. Wagner’s Handw. d. Physiol. Bd. II, p. 131.
Meeh, C.
1879. Ztschr. f. Biol. Bd. XVIII, p. 425.
Rauber, A.
1893. Lehrbuch der Anatomie des Menschen. 4. Aufl.
Sherrington, C. S.
1894-95. /. Physiol., London, XVII, p. 211.
Stilling, B.
1859. Neue Untersuchungen iiber den Bau des Riickenmarks, Cas-
sel, p. 602.
Voischvillo, |. (or Woischwillo).
1883. Relation of Calibre of Nerves to the Skin and Muscles of Man.
(Russian). St. Petersburg.
Weber, E. H.
1846. Wagner’s Handw. Bd. 3, Abth. 2, p. 500.
ON A SAW. DETERMINING THE NUMBER (OF
MEDULLATED NERVE FIBERS INNERVATING
ia iniGh, SHANK AND) POOP OF | THE
FROG—RANA VIRESCENS.
By Henry H. Dona.pson.
(From the Neurological Laboratory of the University of Chicago.)
During the past three years, while following the studies of
Dr. Dunn (1900 and 1902) on the innervation of the frog’s leg,
it has been my endeavor to discover whether there was any law
determining the distribution of the medullated nerve fibers to
the segments of the leg. This law has been found and is
expressed as follows :
The nerve fibers entering the leg of the frog (Rana virescens)
by the sciatic and crural nerves, are distributed to the thigh, shank
and foot in numbers which, for each of these segments are equal
to the sum of the efferent fibers,—taken in proportion to the weight
of the muscles,—and of the afferent fibers,—taken in proportion to
the area of the skin,
The data discussed in the following pages are intended to
furnish the evidence for the law just stated.
To make this investigation it was necessary to know:
(1) The relative number of medullated ventral and dor-
sal root fibers in the nerves supplied to the frog’s leg.
(2) The relative weight of the muscles of the thigh,
shank and foot.
(3) The relative areas of the skin for the thigh, shank
and foot.
(4) The number of medullated nerve fibers entering the
leg and also the number distributed to each segment.
(5) The number of medullated fibérs distributed as mus-
cular and cutaneous nerves to each segment of the leg.
224 JouRNAL OF CoMPARATIVE NEUROLOGY.
With the exception of the data called for under (3), the
facts needed were to be found in papers already published from
this laboratory. We shall take up the points in the order just
given.
(7) The relative number of medullated ventral and dorsal
root fibers in the nerves supplied to the leg.
The nerves sending fibers to the leg are the VII, VIII and
IX spinal nerves as usually numbered, or, according to the
recent numbering of Gaupp (1897), the VIII, IX and X.
According to the enumeration of the medullated nerve
fibers in the dorsal and ventral roots of these nerves by Har-.
DESTY (1899, p. 84), the proportion is.
TABEEGE:
Relative number of fibers in roots,
Ventral. Dorsal.
Frog weighing 48 grams 100 177
ie te 59 grams 100 175
The average of these two observations gives therefore 100
ventral root fibers to 176 dorsal root fibers, and this is the ratio
here employed. Such being the relation found in the spinal
roots, it is assumed to be the same in the sciatic and crural
nerves at the point where they enter the leg. Whatever the
number entering of fibers the leg, they are then to be divided,
as motor and sensory, in the above proportion.
In this calculation no correction for possible efferent fibers
in the dorsal roots is attempted, for we have no data with
which to work. When efferent fibers appear in the dorsal
roots of the frog, there is indirect evidence that the number
must be quite small, and they are here neglected (HortTon-
SMITH 1897, Wana 1898, Date 1901). The ventral root is
assumed, therefore, to contain only motor or efferent fibers
and the dorsal root only afferent or sensory fibers.
Having determined the proportional numbers of the
afferent and efferent fibers, the next step is to present the meas-
urements according to which these fibers are to be distributed,
namely, the relative weights of the muscles and the relative areas
of the skin in the several segments of the leg.
Donatpson, Law of Innervation. 225
(2) The relative weight of the muscles of the thigh, shank
and foot.
In an earlier study, made in collaboration with Mr. ScHoeE-
MAKER (1900) it was determined in Rana virescens that the
relative development of the muscles of the frog’s leg, as indi-
cated by the weight of the muscles of the thigh compared with
those of the remainder of the leg, was nearly constant for all
groups above five grams in body-weight (see DonaLpson and
SCHOEMAKER, 1900, pp. 124-125).
TABLE ILI.
Giving in grams the weights of the muscles in the thigh, shank and
foot of the Frog—R. virescens. (From Table VII, DonaLpson
and SCHOEMAKER, 1900.)
Boay Weight of Muscles
No| Sex | Weight | Leth. | Thigh| Shank} Foot
rigeil| oly 29.40 E85) | 3-LO5| Koray) 2533
3-097 1.201] .538
O| 1.240] .659
19] -F | 30-45 179 | 3-3
era -195| .603
GQ Go
ho
|
_
20| F 33-96 172 3-480] 1.393} .603
3-681) 1.354] .631
22| M | 38.16 200 | 3-637} 1.563) .715
3-536] 1.456} .653
23) ik 42.54 215 4-455| 1.562) .822
4-369) 1.535] .843
_
25} M | 45.37 205 | 4-383) 1.496] .869
4.278] 1.493 816
-797| 1.844] .926
.830| 1.828} .926
4
4
AA Ae 47-58 206 4.
4
713) Deepal. 824
-616) 1.813} .871
23) F 48.33 220 | 5-402; 1.906) 1 006
§-430| 1.949] 1.019
> 2c 52.55 206 | 5-404) 2.450) .835
5 456) 2.400] .850
226 JoURNAL OF COMPARATIVE NEUROLOGY.
From Table VII, in that paper is taken the following series
of records comprising numbers 18-29, inclusive, (excluding
numbers 21 and 24 for which the muscle weights were not
determined). This is the series just as it stands in the original
table, and these same records have also been employed in my
paper ‘‘Ona Formula for Determining the Weight of the Cen-
tral Nervous System of the Frog from the Weight and Length
of its Entire Body,”’ 1902.
For a description of the method by which the weights of
the muscles were determined, the reader is referred to the
original paper (p. 118).
For the first five frogs entered in the table, calculation
gives the following proportional values for the weights of the
muscles of the thigh, shank and foot:
TABLE III.
Segment of Leg
Percentage Value of Weight of Muscles.
Thigh -63-9%
Shank 24.3%
Foot 11.8%
In the case of the second five frogs in this same table, the
proportional values are as follows:
TABLE, LY:
Segment of Leg, Percentage Value of Weight of Muscles.
Thigh 63.9%
Shank 245%
Foot 11.6%
It will be seen that these two series differ only by some
tenths of a percent. in the case of the shank and foot, so that
the relative values may be considered fairly constant.
For use in the present investigation we take the average of
the two series which gives:
TABLE V.
Segment of Leg. Percentage Value of Weight of Muscles.
Thigh 63.9%
Shank 24.4%
Foot 11.7%
Having obtained the data according to which the motor
fibers entering the leg should be distributed, we need next to
Donatpson, Law of [nunervation. 227
obtain the corresponding data for the areas of skin, —in accord-
ance with which the afferent fibers are to be distributed.
(3) On the relative areas of the skin of the thigh, shank,
and foot.
Since the relative weights of the muscles in the several
segments of the frog’s leg remain unaffected by the size of the
frog (DonaLpson, 1898, and DonaLpson and SCHOEMAKER,
1900), and since the conformation of the leg is similar in large
and small frogs, it follows that the relative areas of the skin
covering the different segments of the leg are unaffected by the
absolute size of the frog examined. This removes the neces-
sity of always working with frogs of the same size.
My acknowledgments are due to Dr. Dunn for working
out the area of the skin in the several segments of the frog’s
leg. As the method used was somewhat novel, it will be nec-
essary to describe it in detail.
The frogs examined had the following body measurements:
TABLE VI.
Frogs examined for area of skin.
Length from tip of nose to
Frog No. Body Weight, grams. end of longes !toe.
g y ght, ¢ g
I 34.76 190 mm.
Zz 36.75 195 mm.
B 28.17 187 mm.
The procedure was as follows: The frog was killed with
chloroform and pinned out on a sheet of cork with the ventral
aspect uppermost. One leg was extended and abducted so
that it made an angle of about forty-five degrees with the longi-
tudinal axis of the body. A strip of glass about 3 cm. wide
and a few centimeters longer than the frog’s leg, was then
passed beneath it. The leg thus rested on this strip of glass
and was in turn covered by a similar strip of the same size.
On the upper surface of the latter a layer of tracing paper had
been fastened by a drop of paste at each of the four corners.
Rubber bands were next passed over the two strips of glass
and the leg lightly compressed between them. Before putting
on the covering strip, however, the foot was stretched so as to
228 JOURNAL OF COMPARATIVE NEUROLOGY.
exhibit the full extent of the web. For this purpose, threads
were tied to the first, third and fifth toes, pulled taut and fast-
ened by pins. The web was stretched until the second toe
showed a tendency to curl up, and this reaction was regarded
as indicating the normal extension of the web. When so
extended, the general outline of the foot is that of a quad-
rilateral.
These adjustments having been made, it was determined
by measurements taken between the two strips of glass, that
their faces were approximately parallel. Next an outline,
just outside the contact line of the upper glass with the skin of
the leg, was made with a pencil on the tracing paper, starting
from the uppermost part of the thigh on one side, and follow-
ing around the entire outline of the leg to the uppermost part
of the thigh on the opposite side. The upper limit between
the skin of the body and that of the thigh was marked by the
adjustment of the glass strips, and the levels of the knee and
ankle joints respectively, were fixed by passing needles through
these joints when preparing the leg for this examination. By
drawing, therefore, a line across the tracing paper at these
several levels, the outlines for the thigh, shank and foot were
obtained. It was assumed that the outline on the dorsal aspect
of the leg would be similar to the one found on the ventral
aspect. To obtain the areas for the sides of the leg, the dis-
tance between the two glasses at the hip, knee and ankle was
measured and the length of the curved line (the ‘‘coast line’)
forming the lateral boundary in the case of the thigh and
shank, taken on each side, by means of a waxed thread applied
to the outline. This gave the initial measurements for the cal-
culation of the area of the skin of the thigh and shank. Con-
cerning the foot we shall speak later.
To illustrate the determination of the area for a given
segment, let us take the thigh. In this case we have the area
marked on the tracing paper between the boundary separating
the thigh from the body and that separating it from the shank.
The content of this area was determined in square millimeters
by means of a planimeter and then doubled so as to include the
Donatpson, Law of lnnervation. 229
corresponding area on the opposite side; to this sum was
added the areas obtained by multiplying the length of each
curved side (the ‘‘coast-line’”’), by a number equal to half the
sum of the height of the side at the hip plus its height at the
knee.
The sum of the four areas thus obtained was considered as
the total area of the skin of the thigh. By following the same
steps, the total area of the skin of the shank was found. On
coming to the foot, however, the method of determining the
area required to be modified in order to include the additional
surface represented by the toes. The original outline on the
tracing paper gave the area of one side of the foot projected
on a plane surface, to which, when doubled, should be added
the amount represented by the elevation of the toes and that
due to the thickness of the tarsus.
To illustrate the method used, the following figure is
given: |
230 JoURNAL OF COMPARATIVE NEUROLOGY.
Knee
Ankle
Figure 7. Outline of Frog’s leg, showing the outline of the ventral aspect
of right leg. AHi#p—marks the junction line of the body with the thigh.
Knee—the junction line of the thigh with the shank. Am&/e—the junction
line of the shank with the foot. D’—D.—length of tarsus plus second toe.
M-A—length of fifth toe. A/’—#.—length of fourth toe. M’’—C—length of
third toe. (Second toe measured with tarsus). J/ ’’—#—length of first toe.
Donatpson, Law of /nunervation. 231
The length of the line D/-D was first taken, then the
thickness of the foot at D’ and at D. Half the sum of these
last two measurements multiplied into the length D’—D gave the
lateral areas of the foot, considering these as extending from
the ankle joint to the tip of the longest toe, and twice this
gave the areas for both sides. The length of the lines JA,
M'B, M'' Cand M''' Ewere then taken, and the thickness
githe, footcat Wi, 07’, A7'', M'"! and at ‘each ‘of the” toes
A, B, Cand £ (D being omitted, as it had been already meas-
ured). Half the sum of these two thicknesses was taken in
each case as the average thickness of the toe, and the product
of these numbers into the length of the respective toes, gave
the area of the skin on one side of the toe considered as a
plane surface. The surface is so rounded, however, that about
one-half of the area thus calculated has already appeared in the
surface projection of the foot, and has been counted in the
area incluced within the original outline; therefore, intstead of
taking this area for the side of the toes twice, it was taken
only once.
Thus to get the total area for the foot, there are added
together: the two areas from the tracing—the number of
square millimeters being determined by the planimeter—the
area for the longest toe including that for the sides of the tar-
sus and finally the additional areas for the four remaining toes.
The areas thus obtained for the three frogs measured are
given in the accompanying table, the records for the two legs
being entered separately.
TABLE VII.
Giving the areas in square millimeters of the skin covering the thighs,
shanks and feet of three frogs—R. virescens. The method of
measurement is given in the text.
Areas in Square Millimeters.
—
Frog. Thigh. Shank. Foot.
1 Right 1584.1 1136.8 1695-3
1 Left 1675-5 1059.0 1793 6
2 Right 1519.2 1071.5 1539-1
2 Left 1506.3 1035-0 1538.7
3 Right 3177/0) 1010.9 1396.5
2) Left 1356.2 972.4 1434.1
Totals 9018.3 6285.6 9397-3
232 JOURNAL OF COMPARATIVE NEUROLOGY.
‘When the percentage values of these numbers are found,
they give the following:
TABLE VIII
Average for first Average for second Average for all.
Segment. 3 entries 3 entries 6 entries.
Thigh 36.5% 36.5% 39.5%
Shank 25.0% 25.8%, 25.4%
Foot 38.5% 37-7% 38.1%
On attempting to apply these percentages in the calcula-
tion for the supply to the leg, it was found that the numbers
obtained were somewhat larger than we expected them to be
in the case of the thigh. It appeared that the area for the
thigh had been over-estimated. Dr. Dunn therefore undertook
a reinvestigation of the innervation of the skin of the thigh.
This showed that the area was over-estimated in this sense, that
in addition to the fibers entering the leg by the sciatic and
crural nerves. there was a small independent bundle of nerves
which entered through the anus and was distributed to a small
triangle of skin just behind the anus and on the mesal surface
of the leg. The area of this piece of skin thus innervated,
was found to be 2.5% of the area of the entire thigh. For
the details of this determination the reader is referred to a
forthcoming paper by Dr. Dunn.
To control these results, other measurements were made
by an entirely different method. A plaster mould of the frog’s
leg was taken and the leg then cast in Woops metal. On this
cast the thigh and shank were examined for their respective
areas by winding them carefully with fine copper wire—of a
uniform diameter. The diameter being constant, the areas
covered by the wire would be directly proportional to the
length or weight of the wire used. The relations were tested
by weighing the wire. The weight of the wire needed to
envelop the thigh, was to that needed to envelop the shank
as 1.43: 1.
On comparing this ratio with that from the areas for the
thigh and shank, as shown in Table 7, it appears that this ratio
is also 1.43: I.
Thus the proportional areas for the thigh as determined
Donatpson, Law of Innervation. 233
by these two methods are identical. It would follow from
this that the first method was probably accurate. On account
of its shape the foot cannot be tested by this latter method.
When the area of skin for the thigh is reduced by the
amount which is not innervated by fibers entering the leg in
the sciatic and crural nerves, the following percentages are
obtained as a general average from the three frogs measured :
TABLE IX.
Area of Skin.
Thigh 35.9%
Shank 25.7%
Foot 38.4%
The above percentages are those used in the calculations
which follow.
(4). The number of medullated nerve fibers entering the leg
and also the number distributed to cach segment.
Having thus determined the proportion in which the ven-
tral root fibers and the dorsal root fibers entering the leg should
be distributed to the several segments, it becomes desirable to
estimate by means of the preceding tables, the total number of
fibers going to each segment.
To show how this is done, let us assume that 100 ventral
root fibers and 176 dorsal root fibers enter the leg—these num-
bers are in the proportion which has been determined. Then
63.9% of the 100 ventral root fibers go to the thigh and 35.9%
of the 176 dorsal root fibers also go to the thigh. Now, in
order to determine what percentage of the total 276, the sum
of these two numbers is, we should divide their sum, namely,
63.9 fibers+63.2 fibers = 127 fibers by the total number of
entering fibers, namely, 276. We then find that 46% of all
the entering fibers go to the thigh when they are distributed in
the above manner.
Extending the calculation in the same way to the shank
and foot, we may tabulate the results as follows:
234 JoURNAL OF COMPARATIVE NEUROLOGY.
TABLE X.
Hereafter designated as the ‘‘formula’”’.
46% go to the thigh
25.3% go to the shank | eer shank 46.8%
28.7% go tothelfoot ) {my Jo foot 53.2%
100.0% go to the leg.
If 46% go to the thigh, then 54% go to the remainder of
the leg, i.e., shank and foot combined. Further, if we consider
alone the fibers which go to the shank and foot and express
the number as 100%, then of this 100% going to the shank
and foot, 46.8% go to the shank and 53.2% to the foot.
These calculations of the fibers distributed to the shank and
foot are introduced here as they will be used later on.
The values inthe above Table X are those with which
all the subsequent calculations are made. It remains now to
present the data concerning the number of nerve fibers
observed to enter the leg of the frog and then to see in how far
the estimated numbers for the segments of the leg correspond
with the numbers which have been observed.
These observed numbers have been obtained by Dr.
Dunn. The designation of the frog and the segment or seg-
ments for which the enumerations have been made, together
with the date of publication, are given in the following Table
XI in chronological order:
TABLE Xl.
Frog B Thigh DUNN 1900
Frog C Thigh DUNN 1900
Frog B II Thigh, Shank and Foot DUNN 1902
Frog C II Thigh, Shank and Foot DUNN unpublished
Below are given the details of the data for each frog so far
as they will be required in this study.
The accompanying Figure 2, taken from Dr. Dunn’s
paper (1902), shows the levels at which the nerves for the
frog’s leg were sectioned and where the number of fibers was.
counted.
Donatpson, Law of Innervation. 235
> Ol D. Cre
al
Sat aa dal
)
Figure 2. Diagram of the innervaticn of the Frog’s Leg, showing the
levels at which the number of nerve fibers was counted. C—level of Crural
nerve just above branches to thigh. Sv—level of Sciatic nerve just above
branches to thigh. Sz2—=level of Sciatic nerve just below branches to thigh.
P=level of Peroneal nerve just above branches to shank. Z=level of Tibial
nerve just above branches to shank. Pr, P2=level of Peroneal nerve just
above branches to foot. 77, 72=Ilevel of Tibial nerve just above branches
to foot.
236 JOURNAL OF COMPARATIVE NEUROLOGY.
Thus all the fibers entering the leg were in the sections at
the levels C+S,. All the fibers entering the shank were in the
sections at P+T, and all the fibers entering the foot at P1+P2
and T1+T2.
In the Tables XII-XVI which follow, these designations
are used to indicate the levels at which all the fibers for a given
segment were to be found. Below the entry for the number of
fibers to each of the segments, stands ‘‘To Thigh” and ‘‘To
Shank,’ which means that all the branches to the thigh or to
the shank contained the numbers there entered, under
‘‘observed.”’ The number of fibers immediately below the
branches to the thigh is also given after Su».
In the column headed ‘‘ muscular and cutaneous,”’ are the
observed numbers found in the muscular and cutaneous
branches and their sum is equal to the ‘‘ observed number ’”’ in
each case.
In the column headed ‘‘calculated,’’ we have the number
determined by Dr. Dunn by taking the difference between the
number just above the branches to the thigh (C+S, ), or shank
(P+T), and the number just below at S: or at Pi+P2 and
ash:
In the column marked ‘‘splitting fibers,” we have the
’
difference between the observed—the larger number—and the
calculated—the smaller number—which difference is due to
fibers that have split in their course so that they are repre-
sented either by two divisions having the same distribution
(i. e., both run in the branches supplying the segment), or by
one division running in the branches to the segment, and by
the other in the main trunk of the nerve to some point below
the Jevel of the branches. It is the presence of these splitting
fibers which renders complicated the application of the test
which it is proposed to make, since the formula based on the
law of distribution does not take account of the additional fibers
which appear as the result of splitting.
DonaLpson, Law of Innervation.
237
TABLE XII.
Data taken from Dr. DuNn’s paper, 1900; Tables III, IV, V and VI.
Frog B.
Locality
C+S,
To thigh
Sy
C+5,
To thigh
S,
Right Leg.
Left Leg.
Number of Fibers
Observed Calculated Splitting Fibers
Cutaneous = C
sare) Muscular = M
0
C ( 876
2623 2405 218
M (1747
28680 eases yi Sees e Sy ee
5385 0-H ---- we ne
CO (RS 71
2600 2411 189
M (1729
2074. weneee een wee
TABEE XIII.
Data taken from Dr. DuNnn’s paper, 1900; Tables III, IV, V and VI.
Frog C.
Locality
c+5,
To thigh
S,
C+5S,
To thigh
S,
Right Leg.
Left Leg.
Number of Fibers
Observed Calculated Splitting Fibers
Cutaneous = C
Total Muscular = M
6011
--<-<=<= @-—-<-<=<= =eeen=
238 JOURNAL OF COMPARATIVE NEUROLOGY.
TABLE XIV.
Data taken from Dr. Dunn’s paper, 1902; Tables V to XIV inclusive.
Frog B II.
Locality
C+5S,
To thigh
S,
| ao
To Shank
Pi -+ P2and T1-+ T2
Right Leg.
Number of Fibers
Observed
Cutaneous = C
Total Pee = M
rite iak pee eaee
TABLE XV.
Calculated
Splitting Fibers
Data taken from Dr. DuNnn’s paper, 1902; Tables V to XIV inclusive.
Frog B II. Left Leg.
Locality
c+5S,
To thigh
Sa
PT
To shank
Pr-+ P2and Ti + T2
Number of Fibers
Observed
Cutaneous = C
Total Muscular = M
ie ak oo
Calculated
Splitting Fibers
DonaLpson, Law of lnnervation. 239
TABLE XVI.
Data from specimen of R. virescens. Body-weight 51 grms. Ob-
servations by Dr. DUNN not previously published. The section
at S; of the left leg was unfortunately too imperfect to be counted.
Frog C II. . Right Leg
Number of Fibers
Locality Observed Calculated Splitting Fibers
f Cutaneous = C
oe \ Muscular = M
1301 C
an lees Si
OMIM Aye eos ty 0M) Oe ee te MUNG hy reece
Sy S338 a ———— ee
a eee eee 2a OZ yw eee! Bo ee eee Sh tt Ue ee
Left Leg
- = 1323,€
See { vals S Si (section lost) soa2n— es einem
S, Bg800 ieeecoeaeyne a ienoamoe 1) AM RE one
IPR te Jes ahavel, Wi Aad, ikolsso) (= SER eke eet
To illustrate the use of the data in the foregoing tables,
we will take the right leg of Frog B II (Table XIV), and
determine how far the observed numbers there given agree with
those estimated by the aid of my own formula. Table XIV
shows 7107 fibers entering the leg. When the proportional
numbers are calculated according to the formula (Table X), we
obtain the following:
TABLE XVII.
Entering right leg of Frog B II— 7107 fibers
To thigh— 46.0%= 3269 fibers
To shank— 25-3%= 1796 fibers
To foot— 28.7%= 2042 fibers
The above numbers of fibers are the numbers of single
pathways between cach segment of the leg and the entering nerve.
When the observed numbers of fibers to the several seg-
ments of the leg (see Table XIV) are compared with those
here estimated, we obtain the following:
240 JOURNAL OF CoMPARATIVE NEUROLOGY.
TABLE XVIII.
Number of fibers to the several segments of the right leg of Frog B IT.
Estimated Observed
(DONALDSON) (DuNnN)
To thigh 3269 3508
To shank 1796 2130
To foot 2042 2497
Thus in every case the numbers estimated by the formula
are less than those observed by Dr. Dunn. But as Table XIV
shows, Dr. Dunn’s count includes a large number of fibers
which have split (see ‘‘splitting fibers” in tables), and which,
therefore, are not taken into account by the formula, which
applies to single pathways only.
The next step, therefore, in the comparison is to bring the
two series of numbers to the same standard. There are two
ways of doing this, namely, either by removing the additional
fibers due to splitting from the number observed by Dr. Dunn,
or by adding the additional fibers to the number as determined
by the formula. The latter method was followed; first,
because it was desirable to consider the odserved number as the
fixed standard, not to be altered in any way, and second,
because it seems probable that the most direct utilization of
this formula will be for determining the number of fibers which
a direct count would show to be supplied to a given segment.
Thus in the further work, the observed number is in each
case taken as the standard, and the calculations are directed to
determining the number which must be added to that estimated
by the formula in order to make it comparable with the stand-
ard. To illustrate the stéps taken for this purpose, we shall do
best to examine the innervation of the thigh in the case chosen,
namely, the right leg of Frog B H. My estimation gives for
the thigh 3269 fibers and Dr. Dunn’s observation 3508.
When, however, in this instance the number of fibers observed
above the branches to the thigh at (C+S:) was diminished by
the number observed just de/ow the branches at (S:), the
difference was found by Dr. Dunn to be 343 (see Table XIV).
Thus her observed number exceeded her number calculated in
this manner by 343 fibers. This excess is explained as the
Donatpson, Law of Innervation. 241
result of splitting fibers and means—if dichotomous splitting
be the form assumed—that 343 of the fibers counted at C+S,
have split later into two divisions each. Just where this split-
ting occurs, we are obliged to guess. The numerical results
indicating the number of splitting fibers would be the same,
whether it occurred in the main stem, C+Si, just where the
branches to the thigh are given off, or within the branches after
these had been given off, but before the levels at which they
were individually sectioned. For the further development of
our idea of the innervation of the leg, however, these two pos-
sible arrangements leading to like numerical results, have very
different values. In the latter instance, where the splitting
occurs within the branches, the splitting fiber is in no wise rep-
resented in the main trunk of the nerve below the level of the
branches, whereas in the former instance, where splitting occurs
in the main trunk, one division can appear in the branches and
the other. continue in the trunk, the original fiber being there-
fore still represented in the trunk, below the point at which it
has split.
It was necessary to assume that some of the fibers that
split did so in the trunk, and thus were represented both in the
branches and in the trunk below the branches, while others
split in the branches themselves; both divisions in this case
having a similar distribution.
After several tests, it was found that the most accordant
results were obtained when it was assumed that one-third of the
splitting fibers split in the branches. Fibers splitting in this
way form Class a. Since the total number of splitting fibers
was in this case 343, one-third would be 114.3 fibers. These
are to be added to the number estimated by me (see Table
EGVAI 3200 C114. 3-3 333. 3:
The number of fibers that pass to the shank and foot is
not affected by this process, since each one of these fibers split-
ting in the branches is without representation in the trunk
below the level of the branches.
By this step 114.3 of the splitting fibers have been with-
242 JOURNAL OF COMPARATIVE NEUROLOGY.
drawn from the original 343, leaving 228.7 to be still
considered.
These remaining fibers are assumed to be of the second
class of splitting fibers (Class b), i. e., those, one division of
which passes into the branches, while the other continues in
the trunk below the branches.
Since by the formula we have taken 46% of the total
number of the fibers entering the leg (see Table XVII), we
must assume that we took 46% of the fibers with double rep-
resentation (Class b). It follows, therefore, that in the original
46% or 3269 fibers, there are already included 46% of the
fibers with double representation, or 46% of the 228.7 fibers
which constitute Class b at this level. Therefore, to bring the
estimated up to the observed number in this respect, there are
still to be added to the estimated number 100%—46%=54 %
of 228.7, which equals 123.5 fibers. In general, therefore, to
make the estimated number comparable with that observed by
Dr. Dunn, we should add one number representirg the fibers
splitting in the branches (Class a), and also a second number
representing the splitting fibers with double representation
(Class b), in so far as they have not been included in the
original 46%.
TABLE XIX.
Showing the number of fibers to be added to the original 46% in the
case of Frog B II—Thigh.
Calculated numbers. Observed number
Original 46% == 209
Fibers splitting in branches (Class a) = AGS
Splitting fibers with double repre-
sentation (Class b) eRe s
3506.8
or 3507 3508
Difference = I fiber
As the table shows, the estimate is almost identical with
the observation, being but one fiber less. Without comment-
ing on this result at this place, we shall pass on to the consider-
ation of the nerve supply to the shank of this same leg.
It must be kept clearly in mind that our calculation for the
Donatpson, Law of Lnnervation. 243
percentage distribution of the fibers to the segments of the leg
applies to the number of szxzgle medullated fibers found entering
the leg at C+S; in this case, 7107 fibers. Having removed
46% of this number for the innervation of the thigh, there
remain 54% to be distributed to the shank and foot.
Thus: 7107—3269=3838 fibers.
The law calls for a distribution of this 54% of the initial
number in the proportion of 25.3% to the shank and 28.7%
to the foot. When, however, we attempt to deal with the
splitting fibers belonging to the shank and foot in making the
estimated comparable with the observed results, it is necessary
to distribute these splitting fibers in the same proportions in
the branches to the shank as they were distributed in the
branches to the thigh, and in order to make the distribution in
a like manner, it is necessary to treat the number of fibers
going to the shank and foot, 3838, as 100% of all the fibers
concerned, and then designate those to the shank as 46.8% of
the same number,
Since 46.8% of 3838=25.3% of 7107=1796
53-2% of 3838=28.7% of 7107=2042
According to the formula, therefore, 1796 fibers (single
pathways) are estimated as going to the shank. Dr. DuNnN
observed 2130 fibers to the shank, and further, by the same
methods as were employed in the case of the thigh, she deter-
mined that there were 465 splitting fibers in the branches to
the shank. (See Table XIV.)
In adjusting the estimated number to that observed, these
splitting fibers are treated in the same manner as those found
in the supply to the thigh, i. e., one-third are taken as
dividing in the branches, and of the remainder it is assumed
that 46.8% are included in the original estimate, so that 53.2%
only need to be added to bring the estimate to the same stand-
ard as that of the observed number. Thus, imitating Table
XIX, for the thigh, we have the following:
244 JOURNAL OF COMPARATIVE NEUROLOGY.
TABLE XX.
Showing the number of fibers to be added to the original 25.3% in
the case of Frog B II—Shank.
Calculated numbers. Observed number
Original 25.3% of 7107 or 46.8% of 3838 = Tos
Fibers splitting in branches (Class a) = 155
Splitting fibers with double representa-
tion (Class b) = 165
2116 2130
Difference —= —1Z¢4 fibers or 0.6%
The approximation between the estimated and observed
numbers is not so close here, but is still fair, being within less
than one per cent.
The number of fibers to the foot has still to be considered.
In the case of the foot, the observed numbers are taken from
the enumeration at the levels P1+P2 and T1+T2. Figure 2.
These levels would correspond to those just above the branches
in the case of the thigh and shank. We have to assume,
therefore, that in the number observed by Dr. DuNN at these
levels as going to the foot, there are in addition to the single
pathways represented by fibers that pass unsplit from their
entrance into the leg, two other classes, those namely (a) that
have split within the trunk, both divisions descending to the
foot, and (b) all other split fibers, one division of which goes
to either the thigh or shank, while the other goes to the foot.
Of the class (b), there are in the entire leg at least three
groups: bi, the fibers which split, one division passing to the
thigh and the other to the foot; bs, fibers which have split,
one division going to the thigh and the other to the shank;
bs, splitting fibers which have one division going to the shank
and one to the foot.
These several groups are all marked, Figure 3, as in bi, by,
bs. At the level where the nerves enter the foot, it is neces-
sary to make allowance for groups bi and bs of class (b), as
well as for representatives of class (a).
According to formula, 2042 fibers pass into the foot. Dr.
Dunn observed 2497. To make the estimated number com-
parable with that observed, the allowance for the splitting fibers
Donatpson, Law of Innervation. 245
must be introduced. The principle involved in making the
allowance is that the division of any splitting fiber which has
already been counted asa fiber entering the leg is to be con-
sidered as additional, and hence added to my estimate of the
number to the foot.
For example, the splitting fibers included in the original
46% of those entering the leg and sending one division to the
thigh (bi) are pictured as sending the other division to
the foot.
This group (b,) contributes 106 fibers to the foot. As
the fibers representing these divisions have already been ac-
counted for, they would not appear in my estimate, and hence
must be added to it. In like manner, the long divisions of the
splitting fibers which go to the shank come from fibers already
counted and are therefore additional; thus these also should be
added to my estimate. The latter group (b,) represents
46.8% of the splitting fibers which pass to the shank and these
amount to 145. To the original estimate of 2042, therefore,
106+145=254 is to be added, making a total of 2293 fibers.
This number is still 204 fibers less than the observed 2497.
The difference may justly be credited to the splitting fibers of
class (a), namely those, both divisions of which have a like
distribution. That many such splitting fibers occur is shown
by Dr. Dunn’s observations (1902, p. 314).
The arrangement of the fibers as here imagined is exhib-
ited in Figure 3, which is purely a schema. Here the largest
column represents the fibers going to the thigh, the next
largest those to the foot and the smallest those to the shank.
The size of the columns is proportional.to the number of fibers.
they contain.
246 JOURNAL OF CoMPARATIVE NEUROLOGY.
FIBRES
ENTERING LEG
100%
THIGH FooT SHANK
oa
8.7%
To Foot
Figure 3. The explanation of this schema intended to illustrate the arrange-
ment of the splitting fibers distributed to the leg of the frog, is given on the
following page.
Donatpson, Law of Innervation. 247
All the fibers entering the leg by the crural and sciatic
nerves are enclosed within the circle marked ‘‘Fibers entering
the leg, 100%.’’ Atthe next lower level, the small circles
enclose all the fibers to each of the three segments of the leg
marked respectively :
Thigh 46.0%
Shank 25.3%
Foot 28.7%
Within the last three columns the heavy black lines indi-
cate the splitting fibers, which according to the description in
the text, are distributed to the the thigh, shank and foot. These
splitting fibers are divided into two classes :
Class a—splitting fibers, both divisions of which are dis-
tributed to the same segment :
Class b—splitting fibers, the divisions of which are dis-
tributed to different segments.
This latter class is represented by three groups:
bi, one division of which goes to the thigh and the other
to the foot ;
b,, one division of which goes to the thigh and the other
to the shank;
bs, one division of which goes to the shank and the other
to the foot.
C + Si, indicates the level above the branches to the thigh;
P + T, the level above the branches to the shank, and P1 + P2
and T1 + T2, the level above the branches to the foot.
Within each column is represented the several sorts of
splitting fibers, each one bearing the designation used to indi-
cate it in the text. The designation ‘‘a’”’ always indicates the
splitting fibers, both divisions of which have the same distribu-
tion. Class ‘‘b”’ is represented by the three groups, b,, one
division of which goes to the thigh, while the other goes to
the foot ; bs, one division of which goes to the thigh and the
other to the shank, and finally, b;, one division of which goes
to the shank and the other to the foot. The splitting fibers are
counted only once, and are credited to the column in which
they appear above C+S, in the figure. The other divisions are
in addition to the number of fibers called for by the formula.
248 JOURNAL OF COMPARATIVE NEUROLOGY.
The Jevels C+-Si,’P+T; and Pr+P2 and i112 are alam
cated. If there were no splitting fibers the schema would be
made up of the outlines of the three columns alone.
Turning now to general results of this test, we find that in
the case of the right leg of Frog B II, the estimated numbers
agree very closely with those observed when an allowance,
according to a fixed procedure, is made for the splitting fibers.
The significance of this result depends largely on the
possibility of repeating it. Using exactly the same methods,
the results for the left leg of this frog (data presented in Table
XV) are almost as good as those for the right.
The following table presents the results for both legs
Frog, Bull:
TABLE XxXI.
Estimation
(DONALDSON)
Corrected for splitting Observed Difference Percent-
fibers (DuNN) in fibers age
Thigh R 3507 3508 — I —.03%
Thigh L 3497 3481 +16 +-40%
Shank R 2116 2130 —14 —.65%
Shank L 2110 2108 +2 +.09%
Foot R 2497! 2497 Sere =
Foot L 2486! 2486 set’
1 8¢, of the observed numbers being added to represent the splitting fibers
with a similar distribution of both divisions—see text.
This is the only frog we have in which the enumeration at
different levels has been complete enough to permit of this full
test of the formula. In Frog C II, however, the endeavor
was made to determine whether the proportional distribution of
the fibers at different levels in the leg would correspond with
those found in Frog B II, for it seemed very probable that if
the two frogs corresponded in this respect, they would also
correspond in the number of fibers supplied to each segment
of the leg.
The data for Frog C II give the number of fibers entering
the leg at C4 Si the number at S», and the number entering
the foot, at Pr P2 4:/and Tria. T2; see Table Vi
Donapson, Law of Innervation. 249
On adding these three numbers together and then taking
the proportional value of each of them, we find the following :
TABLE XXII.
Level Right Leg Left Leg
C+5, et
S, 29.4%
LS il es aa) Oa A a ee
This calculation could not be repeated for the left leg, as
the sections for Si were imperfect. The remaining sections were,
however, counted at levels C, S: and P1 + P2+T1+ T2 on the
left leg, and gave numbers so closely similar to those from the
right leg, that it is highly probable that the innervation of the
two legs agreed closely.
The tabulation of these same numbers in Frog B II is
given below:
TABLE XXIII.
Right Leg Left Leg
c+S, 51.6% 51.8%
5, 30.2% 30.1%
Pi -+2Pi+T1-+ T2 18.2%, 18.1%
When we compare these percentages with the correspond-
ing determinations for Frog B II, in which the two legs are
quite similar, we find that CII has .8% more in the thigh,
.8% less in the shank and that they exactly coincide as regards
the foot.
If we may judge from this, then other frogs are similar to
B II in the general arrangement of the nerve supply to their
legs, and hence the formula would be applicable to them as a
class.
In support of this view, we have the results of applying
the formula to Frogs B and C. In these cases to be sure, both
legs were examined, but the supply to the thigh alone was ob-
served and therefore the comparison is limited to that segment
of the limb.
As the data for these calculations is to be found in Tables
XII and XIII, it will be necessary to give only the comparison
of the estimated number of fibers in each case with those
observed.
250 JOURNAL OF COMPARATIVE NEUROLOGY.
TABLE XXIV.
Estimation (DONALDSON)
Corrected for the Observed
Splitting fibers (Dunn) Difference Percent.
Frog B
Thigh r. 2577 2623 — 46 —1.7%
Thigh 1. 2608 2600 + 8 +0.3%
Frog C
Thigh r. 2884 2814 + 70 +2.5
Thigh I. 2887 2777 +110 +4.0
If we take the differences between the estimated and ob-
served number of fibers to the thigh in all three frogs, B, C and
B II, we find that the total is 251 fibers, neglecting signs, or
deducting the — fibers from the + fibers, an excess of + 189
fibers. In the first case the difference amounts to an average
of 1.4%, neglecting signs, or +1.1% when the signs are taken
into account.
This is a very satisfactory approximation of the estimate
to the observed number.
In the case of the shank we have only the two observa-
tions on Frog B II, with which to make the test. Here the
approximation is. closer, being 16 fibers when the signs are neg-
lected, or a difference of — 12 fibers regarding the signs. This
gives the percentage values of .37% and—.28%. In the case
of the foot, owing to the fact that we have not the data for con-
trolling the splitting fibers, the divisions of which have a simi-
lar distribution, but credit the differences between the estimated
and observed numbers to this class, the test of the approxima-
tion cannot be made, as it has been for the thigh and shank.
However it will be well to point out the reasons in detail for
thinking that in the nerves to the foot, this class of fibers will
account for the differences which have been found.
In the first place, Dr. DuNN (1902, p. 315, Table XII) has
shown in Frog B II, between S:, just below the branches to the
thigh and T and P just at the entrance of the trunk into the
shank, an interval from which no branches are given off—, that
at the lowest level on the right side there was a gain of 210
fibers and on the left, 184, or 5.3% on the right and 4.5% on
the left, the percentage in each case being based on the number
Donatpson, Law of [nnervation. 251
at S: This is proof positive of the splitting of the fibers
within the nerve trunks. Moreover, in our calculations which
were made to get the estimated number of fibers going to the
thigh, the average value of the splitting fibers of class ‘‘a”’
in these case was 2.9%. For the two shanks of Frog B II it
was 9.2%, while that demanded for the foot was 9.9%, all
these percentages being based on the calculated number of
unbranched fibers to each segment.
The significance of the foregoing paragraph is the follow-
ing: When we assume the splitting fibers of this class to this
amount, the results of the estimation and observation agree
closely, and that in the shank where good agreement is ob-
tained, we have assumed 9.2% of these splitting fibers, where-
as in the foot, at which level our results cannot be tested in
the same way, but where we should expect a prioria somewhat
greater number of splitting fibers of this class, we are com-
pelled to assume only a slightly greater proportion, namely
9.9 0.
The claim made, therefore, for the splitting fibers at this
level of the foot has ample indirect evidence in its favor.
Just at this point it may be fitting to call attention to the
fact that the law here enunciated is deduced from the results
already presented in four different investigations: HarpEsty
(1899), DonaLpson and SCHOEMAKER (1900), and Dunn (1900
and 1902), that these were all independent and undertaken
without any thought of the present problem, and that the data
taken from them have been here employed without any modifi-
cation whatsoever. The only special investigation taken up
after this problem was formulated was the study of the areas of
skin in the several segments of the leg, and the observation by
Dr. Dunn on the nerves in Frog C II, with a view to testing
whether the results on Frog B II might be considered as gen-
erally applicable.
This examination of the data from which the deduction
has been made goes a long way to protect it from the criticism
of bias, either unconscious or otherwise.
It has then been possible to show that, allowing fo
252 JouRNAL OF COMPARATIVE NEUROLOGY.
splitting fibers, the number going to any segment of the leg,
calculated on the basis of the proportional area of skin and the
proportional weight of the muscles, agrees very closely with
the number observed. .
To generalize these results, it is desirable to know, not
only what percentage of all the fibers which enter the leg goes to
any segment, as given by the formulain Table X, but also the
percentage of that number that should be added to the supply
of a given segment, to make it equal to the observed number.
This can be obtained by tabulating in each case the esti-
mated and observed numbers, finding the number of fibers by
which they differ and the percentage value of this number on
the basis of the number estimated.
The averages of the percentages in each case then show
the proportion of fibers which should be added to the estimate
in order to represent the number which would probably be
observed.
TABLE XXV.
Showing the percentage of the estimated number of fibers to be added
in order to make the estimate agree with the number observed.
Thigh
Estimate Added Required
Frog j 46% in calculation to balance
Ber: 2426 151 = 6.2% 197
13}, Ue 2477 131 = 5.3% 138
Cox: 2765 i 4-3% 49
Ci 2754 133 = 4.8% 23
Beir. 3269 237 = 7.2% 239
BIL 3279 228 = 7.0% 212
Total 16970 999 59% 858 = 5.0%
Difference = .9%
Shank
25-3%
Ballo 1796 320 = 17.8% 334
Balle 1802 308 = 17.1% 306
Total 3598 628 = 17.5% 640 = 18%
Difference = 0.5%
Foot
28.7%
BIl. r 2042 455 = 22.3% 455
Baal 2048 436 = 21.3% 436
Total 4090 891 = 21.8% 891 = 21.8%
Difference = 0%
Donatpson, Law of Lunervation. 253
A glance at Table XXV shows (1) that to make the 46%
of the fibers entering the leg equal the number that will prob-
ably be observed to the thigh, 5% of itself must be added to it.
(2) That to make the 25.3% of the fibers entering the leg
equal the number that will probably be observed to the shank,
18% of itself must be added to it.
(3) That to make the 28.7% of the fibers entering the leg
equal the number that will probably be observed to the foot,
21.897 of itself must be added to it.
By the aid of these results, therefore, if one is given the
number of fibers entering the leg, it is possible to estimate
with a high degree of accuracy, the number which will be
found going to any segment.
(5) The number of medullated fibers distributed as muscular
and cutaneous nerves to cach segment of the leg.
The efferent nerve fibers in a given segment are present in
numbers proportional to the weight of muscle and the afferent
according to the area of skin. The muscular nerves must
contain all the efferent or motor medullated fibers, but it would
certainly be very unexpected to find that the cutaneous nerves
contained all the afferent fibers. .
The number of cutaneous and muscular fibers has been
determined in every instance for both thigh and shank by Dr.
Dounvy, and with this we can compare the distribution, calculated
on the assumption that all the afferent fibers have a cutaneous
distribution.
In the following table, in each instance, the calculated
sensory (afferent supply, Cal. S.), is compared with the ob-
served cutaneous (Obs. Cut.) supply—the calculated number
always being the /arger. The absolute difference in number of
fibers is noted and its percentage value given—the number
forming the observed cutaneous supply, being taken as a stand-
ard in calculating the percentage. In like manner, the
observed muscular (Obs. Mus.) supply is compared with the
calculated motor (Cal. Mot.), the observed muscular supply
always being the /arger—the absolute difference in number of
254 JOURNAL OF COMPARATIVE NEUROLOGY.
fibers as well as their percentage values are also given, the
observed number being taken as the standard.
The shank is tested in the same way. For the foot
observations are lacking. A study of the table will show,
_first, that the afferent or sensory fibers going to the muscles of
the thigh are from 45% to 3.8% of the number of the cutaneous
nerve fibers, while the excess of the muscular nerves of the
thigh over the calculated number of motor fibers, is from
25.1% to 3.1% of the muscular nerve fibers.
In the case of the shank, the calculations for afferent
fibers going to the muscles gives from 52% to 37% and an
excess of fibers in the muscular nerves of from 34.3%
to 38.6%.
TABLE XXVI.
Comparing the calculated number of sensory fibers with the number
observed in the cutaneous supply and the calculated number of
motor fibers compared with the number observed in the muscular
supply and giving in each case the number of fibers by which
they differ as well as the percentage value of this number. ‘The
observed numbers being used as the standards.
Difference
Cutaneous Muscular
Frog Thigh Abs. I Abs. %
Bar: Vales 1281 Obs. Cut. 876 405 = —45.0%
Obs. Mus. 1747 Cal. Mot. 1296 "451 = 425.1%
Beale Calais: 1297. Obs. Cut. 871 426 = —48.94%
Obs. Mus. 1729 Cal. Mot. 1311 418 = + 24.24
Gan: Calis: 1436 Obs. Cut. 1279 217 = —17.84%
Obs. Mus. 1535 Cal. Mot. 1451 107 = + 6.8%,
Gaal CalsS: 1424 Obs. Cut. 1219 145 = —I1.3%
Obs. Mus. 1558 Cal. Mot. 1450 85 =+ 5-5%
Beklon Galles: 1743) VObs. Gnte1675) | (65— 3.8Y,
Obs. Mus. 1830 Cal. Mot. 1763 67 = + 3.6%
$2 1) ae Gales: 1748 Obs. Cut. 1676 72 = — 4.39%
Obs. Mus. 1805 Cal. Mot. 1749 56 = + 3.1%
Shank
bid UG ee Cal: S- 1376 Obs. Cut. 1003 373 = —37.09%
Obs. Mus. 1127. Cal. Mot. 740 "387 = ++34-3%
BeWIGle Cals: 1371 Obs. Cut. go3 468 = —52.07,
Obs. Mus. 1205 Cal. Mot. 739 466 = + 38.6%
DonaLpson, Law of Lunervation. 255
From these data it appears probable that in all these frogs
and in every segment of the leg, some afferent fibers are dis-
tributed, with the muscular nerves. Moreover, the proportion
thus distributed is shown to be very variable in the case of
the thigh.
On comparing the proportion of these afferent fibers going
to the muscles in the case of the shank, we find that the num-
ber is relatively larger than to the thigh. The comparison in
the case of the shank B II, should be made, not with the data
for the thighs of all the frogs, but with the data for the thighs
of frog B II. Thus, in round numbers, there are in this
instance, 4% of these afferent fibers to the thigh and 45% to
the shank.
The better supply of the muscles with afferent fibers as we
pass to the more distal segments of the limb, is what we
should expect a priori, though in this case the difference
appears very large.
Conclusions.
The present study is concerned with the number of med-
ullated nerve fibers going to the different segmengs of the
frog’s leg.
1. The nerve fibers entering the leg being considered as
so many separate lines of connection with the several segments
are found to. be distributed in accordance with the law that the
efferent fibers are present in proportion to the weight of the
muscle, and the afferent in proportion to the area of skin.
2. When this statement is reduced to numerical terms, it
is expressed by the following formula:
Of the fibers entering the leg of the frog,
46.07%, go to the skin and muscles of the Thigh.
25.3% go to the skin and muscles of the Shank.
28.79, go to the skin and muscles of the Foot.
3. Since some of the fibers split after entering the leg,
the numbers found in the nerve branches to the segments are
larger than the number of single pathways assigned to the seg-
ment by the formula. Calculation shows that to determine the
number which will probably be observed in each case, the
256 JouRNAL OF COMPARATIVE NEUROLOGY.
number given by the formula must be increased by a certain
percentage of itself:
For the Thigh by 5.0%
For the Shank by 18.0%
For the Foot by 21.8%
4. When due allowance is made for the splitting fibers,
it is found that the agreement between the estimated and
observed numbers is close:
Difference.
oye NSN NGS average of 6 cases = +1.10%
Rorthershankse2 oe asee= average of 2 cases = — .28¢
ForathesHootees=—— pee average of 2 cases =
*The necessary observations for the foot are lacking, though the agree-
ment would probably be close there also.
5. Some of the afferent fibers are distributed to the
muscles. The proportion in the thigh is highly variable. The
one case available shows a larger proportion of afferent fibers
to the muscles of the shank than to those of the thigh, sug-
vesting that in the foot the proportion would be still greater.
Thus, while the number of afferent fibers in a segment
appears to be in proportion to the area of the skin, yet the
distribution of these fibers is both to the skin and the muscles.
The significance of this arrangement can only be determined
by work on other forms, both higher and lower than the frog,
in the zoGlogical scale.
BIBLIOGRAPHY.
Date, H. H.
19g0t. Observations chiefly by the Degeneration Method, on possible
Efferent Fibers in the Dorsal Nerve Roots of the Toad and Frog.
Journ. of Phystol. (Foster). Vol. XXVII, tgor.
Donaldson, H. H.
1898. Observations on the Weight and Length of the Central Nervous
System and of the Legs, in Bull-frogs of Different Sizes. Journ.
Comp. Neurol. Vol. VIII, No. 4, Dec. 1898.
Donaldson H.H. and Schoemaker, D. M.
1900. Observations on the Weight and Length of the Central Nervous
System and of the Legs in Frogs of Different Sizes (Rana virescens
brachycephala, Cope). Journ. Comp. Neurol. Vol. X, No. 1,
Feb. 1900.
DonaLpson, Law of Lnnervation. 27
Donaldson, H. H.
1902. On the formula for Determining the Weight of the Central Ner-
vous System of the Frog from the Weight and Length of its Entire
Body.—The Decennial Publications of the University of Chicago.
Vol. X, 1902. The Untversity of Chicago Press, Chicago.
Dunn, E. H.
1900. The Number and Size ot the Nerve Fibers Innervating the Skin
and Muscles of the Thigh in the Frog (Rana virescens brachyceph-
ala, Cope). Journ. Comp. Neurol. Vol. X, No. 2, May 1900.
Dunn, E. H.
1902. On the Number and on the Relation between Diameter and Dis-
tribution of the Nerve Fibers Innervating the Leg of the Frog,
Rana virescens brachycephala, Cope. /ourn. Comp. Neurol, Vol.
XII, No. 4, 1902.
Gaupp, Ernst.
1897. A. Ecker’s und Rk. Wiedersheim’s Anatomie des Frosches.
Abtheil. 1, i. 1, pp: 191, 1897,
Hardesty, I.
1899. The Number and Arrangement of the Fibers Forming the Spinal
Nerves of the Frog (Rana virescens). Journ. Comp. Neurol. Vol.
IX, No. 2, 1899.
Horton-Smith, R. J.
1897. On Efferent Fibers in the Posterior Roots of the Frog. /ourn. of
Physiol. (Foster). Vol. XXI, 1897.
Wana, Julius.
1898. Ueber abnormen Verlauf einzelner motorischen Nervenfasern
im Wurzelgebiet. Arch. f. d. ges Physiol. Bd. LXXI, p. 555, 1898.
4
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VoutumeE XIII. 1903. NUMBER 4.
oR ELE
JournaLt or Comparative Neuro.oey.
Pie RARE OF THE NERVOUS IMPULSE IN. THE
VENTRAL NERVE-CORD OF CERTAIN WORMS.
By O. P. JENKINS AND A. J. CARLSON.
(From the Hopkins’ Seastde Laboratory and the Physiological Laboratory of
Leland Stanford, Jr. University.)
With 14 Figures.
The physiological properties of the muscles in different
species of worms have been investigated by BrEDERMAN (1,
1889), Furst (2, 1889), UrxkitLy (3, 1896), Borrazzi (4,
1898), SrrauB (5, 1900), and BuppincTon (6, 1902), and
the physiological effects of sectioning the ventral nerve cord,
extirpation of portions of the same, and extirpation of the
cesophageal yanglia have been studied by Logs (7, 1894),
FRIEDLANDER (8, 1894), and Maxwett (9, 1897); but no
observations on the rate of propagation of the nervous impulse
appear to have been made in this phylum. In this paper we
record some measurements, done by the graphic method, of the
rate of nervous impulse in the following species:
Cerebratulus sp. Sthenelais fusca Johnson
Aulastomum lacustre Eunice sp.
Cirratulus sp.? Nereis virens Sars =N. branti Ehlers
Arenicola sp. Nereis sp.
Bispira polymorpha Johnson Lumbriconereis sp. (a)
Aphrodite sp. Lumbriconereis sp. (b)
Polynoe pulchra Johnson Glycera rugosa Johnson
1 The two nemertians worked on were identified for us by Professor R. W.
Cok of Yale University as belonging to this genus, species probably new.
2 The marine annelids were identified for us by Professor H. P. JOHNSON
of Harvard University. Some of them are new species described by Professor
260 JOURNAL OF COMPARATIVE NEUROLOGY.
The work on the marine forms was done at the Hopkins’
Seaside Laboratory, Pacific Grove.
A simple muscle-nerve preparation suitable to the graphic
method is not obtainable in the worms. The preparation we
employed consisted of the ventral nerve-cord in connection with
an anterior or a posterior part of the worm serving as a reacting
portion. This may be called a muscle-nerve-cord preparation
to distinguish it from the simple muscle-nerve preparation.
The length of the nerve-cord obtainable for this preparation is
considerable in some members of the group, and the muscle
part, especially if prepared from the anterior end of the animal,
is strong enough to raise a light lever. The extreme posterior
end of the worm can be used for a reacting portion in few forms
only, owing to its greater fragility. The length of the reacting
portion can be suited to any case; we found a length that gave
a height of contraction of 10 to 20 mm. as magnified by the
lever most convenient, but in worms with well developed chit-
enoid epidermis a less height of contraction had to suffice. .
The apparatus used in the present work was much the same
as that used by us in the work on the determination of the rate of
impulse in molluscs (17, 1903). Many difficulties were en-
countered in preparing the worms for experimentation, but af-
ter many unsuccessful attempts the following method was found
most serviceable. The animal was securely fixed by dissecting
needles, ventral side down, to the moveable floor of a large
moist chamber supported on a universal stand, the point of fix-
ation being sufficiently posterior or anterior to give the desired
length of the reacting portion. In case it was desired to
prepare the reacting portion from the anterior part of the ani-
mal the extreme posterior end was then secured in the same
manner, care being taken that the anterior and posterior points
of fixation were so close together that maximal longitudinal
contraction of the worm between these two points exerted lit-
JOHNSON (Preliminary Account of the Facific Coast Annelids, Prec. Cal. Acad.
Sci., 3rd ser. Vol. I, No. 5, 1897; the Polychaeta of the Puget Sound Region,
Proc. Bost. Soc. Nat. Hist., Vol. 29, No. 18, 1901); and the species not named
are now in his hands for study.
JENKINS AND CARLSON, WVervous Impulse in Worms. 261
tle or no pull on the needles, for when this is the case the worm
breaks in two. The body of the worm was secured to the
board as before in two places: one about I to 2 cm. anterior to
the last and the other about the same distance posterior to
the first point of fixation, care being taken in all cases not to
injure the nerve cord. Between the two anterior and posterior
fixed points the body of the animal was laid open by a longitud-
inal dorso-median incision through the body wall. The body
wall was pinned out to either side and the exposed viscera were
turned to one side or removed. The nerve cord was dissected
free from the adjacent tissue and the entire musculature com-
pletely severed near the reacting portion, so that this was in con-
nection with the rest of the body by the nerve cord only. The
freed portions of the nerve cord were placed on the distal and
the proximal pair of platinum electrodes respectively, and the
muscle was connected with the lever by means of a hook and
thread passing over a friction wheel at the end of the platform.
This general account applies more especially to forms like the
Glyceride and the Lumbriconereidz, but numerous devices
such as narcotics, decapitation, etc., had to be resorted to to meet
the exigencies in other groups. Variations from the general
method are noted with each group.
The complete freeing of the nerve cord from adjacent tis-
sues without impairing its function is extremely difficult, if not
practically impossible, in most worms, partly because of the
small calibre of the cord, and partly because of its more or less
complete investment by the ventral musculature. In Nereis virens
thenerve cord is largeand therefore comparatively easily freed ; in
Aulastomum, Aphrodite and, to some extent, in Arenicola, the
cord runs free in the body cavity; but with these exceptions
we never succeeded in completely freeing the cord from the
ventral musculature.
The severing of the dorso-lateral musculature (the ventral
musculature is severed by the dissecting out of the nerve cord)
between the two points of fixation nearest the reacting portion
was done to prevent complications by possible myelo-conduction.
At the time, we were not acquainted with FRIEDLANDER’S obser-
262 JouRNAL OF COMPARATIVE NEUROLOGY.
vation (8, 1894) on Lumbricus that the contraction of the worm
on stimulating any part of the body does not extend beyond
the segment where the ventral nerve cord has been severed.
But this severing of the musculature involves considerable in-
jury, especially to worms like the Sabellide and Aphrodite,
and to avoid this we ascertained by severing the nerve cord and
stimulating the worms anterior and posterior to the cut that
the contraction with which we had to do in our experiments
never passes beyond the segment where the cord is cut, either
in the postero-anterior or the antero-posterior direction. This
fact makes the operation unnecessary, and it was therefore dis-
pensed with in the subsequent work.
Owing to the necessity of having the fixation points, that
is, the points of application of the two pairs of electrodes, close
enough together to prevent the preparation from breaking off
when being stimulated, the actual distance between the elec-
trodes could not be taken as a measure of the distance of nerve
cord traversed by the impulse. At the end of the experimen-
tation the segments were counted and the distance measured, or
more properly estimated, the preparation being stretched as
nearly as possible like the normally crawling worm or after it
was killed in fresh water. The last method has this advantage
that it gives uniform results but it may not approximate
the true distance any closer. It goes without saying that
neither method gives accuracy. This is especially true of
forms with only slightly developed chitenoid epidermis like the
Sabellidz and Glyceride and therefore capable of great elonga-
tion and contraction. In the Nereide the distance can be mea-
sured more accurately. In Aphrodite and Aulastomum the
entire length of the cord was dissected out and measured. In
addition to this difficulty of obtaining accurate measurements of
the nerve cord other difficulties and serious sources of error
were encountered in the experimentation, chief among these
the activity or ‘‘spontaneous”’ contractions of the reacting por-
tion and its unequal degree of relaxation at the moment the rec-
ords were obtained, and the fact that the same strength of stim-
ulus usually caused greater contraction when applied by the prox-
JENKINS AND Cartson, Nervous Lmpulse in Worms. 263
imal electrodes to the nerve cord near the reacting musculature
than when applied by the distal electrodes some centimeters
away from the reacting portion. The incessant relaxation and
contraction caused, no doubt, in part by the injury in the
dissection and by the pull of the lever, are almost entirely ab-
sent in forms like Bispira and Cirratulus; they are quite pro-
nounced in Glycera and Lumbriconereis and even more so in
Aulastomum, while in Lumbricus they present difficulties
which we have thus far been unable to surmount. The unequal
relaxation of the musculature at the moment of stimulation
caused variations in the height of contraction, which, together
with the unequal efficiency of the distal and proximal stimuli,
rendered comparison of the tracings very difficult, as little
guidance could be had in the height of contraction. We found,
however, that in many instances the height of contraction varied
50% without any appreciable variation of the latent time. But
the latent time seemed to vary with the strength of the stimu-
lus, and stronger stimuli were always used for the stimulation
by the distal electrodes to secure approximately the same
height of contraction as on proximal stimulation. The elec-
trodes nearest the reacting musculature were always placed one
to four centimeters from it and additional precautions were taken
to insure against direct stimulation of the muscle by escape cur-
rents.
The measurements are tabulated in summaries for each
species, but to give an idea of the make-up of these summaries
the standard deviation and the coefficient of variability of indi-
vidual measurements of one typical experiment are given. The
figures present a representative pair of records from each
species. The relaxation phase of the myograms is much pro-
longed and in many cases very irregular, but as this does not
directly concern the present work only the part of the tracings
showing the latent time and the height of contraction is given.
Most of the experiments on the marine forms were carried
out during the summer of Ig01 and 1902, but some records
were also obtained during the winter seasons. In the winter
the temperature of the aquarium varied from 11°C. to 20°C.,
264 JOURNAL OF COMPARATIVE NEUROLOGY.
in the summer from 12°C. to 14°C. The temperature recorded
in the case of Aulastomum is that of the room.
Cerebratulus sp.
Several species of Nemertians are found in abundance at
Pacific Grove, but most of them are of too delicate a structure
to be experimented with by the method employed by us.
a N
a nn A eee eee
POTTY TRICE et IT ILC UML DUA WALA T LAC ASA SSA asm
WAVY
Fig. 1. Cerebratulus sp. Postero-anterior. Length of nerve cord between dis-
tal and proximal electrodes: 5 cm. Rate: 8cm. persec. Time: 50d.
Vv. per sec.
We succeeded in securing but two specimens of Cerebratu-
lus of sufficient strength. These specimens were about 30 cm.
in length, but showed the same tendency to break into small
fragments on irritation, that was manifested by their smaller
relatives. Decapitation failed to quiet them. However, we
secured an unbroken portion of a few centimeters in length from
the anterior part of each specimen. The Nemertians possess
one dorsal and two lateral longitudinal nerve cords, in which
they resemble the Platodes rather than the Annelids. No at-
tempt was made to isolate the nerve cords. The stimulus
reached the cord by application of the electrodes to the ventral
side of the body. Single induction shocks were not always
sufficient for excitation from the distal point of stimulation.
The required intensity of the stimulus is much greater in this
species than in any of the Annelids included in this work.
The length of the portion of the nerve cord between the
two points of stimulation was determined in the specimen while
crawling in the aquarium.
JENKINS AND Carson, Nervous lmpulse in Worms. 265
EXPERIMENT No. 1, Table I, Dec. 26, 19QI.
Distal Proximal
No. of records 6 6
Mean iatent time 1.76 sec. 0.29 Sec.
Standard deviation 0.174 sec.| 0.06 sec.
Coefficient of variability 10 .20
Length of cord: 8cm. Rate: 5.44 cm. per sec.
TABLE I.
Summary of experiments on Cerebratulus sp. _Postero-anterior rate.
No. of No. of records Length of | Ry
experiment Distal Proximal cord in cm. ateia eu.
: 2 8 5-44
= 5 5 5 | 9.0
Aulastomum lacustre.
(Horse Leech.)
Through the kindness of Mr. J. C. Brown of the Depart-
ment of Animal Biology of the University of Minnesota, we re-
ceived a number of large individuals of this species from Lake
Vermillon, Minn. They thrived well in the aquarium, some
kG
AVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAN
Fig. 2. Aulastomum lacustre, Postero-anterior. Length of nerve cord between
distal and proximal electrodes: 11cm. Rate: 63.8 cm. persec. Time:
50 d.v. per sec.
being kept for over three months. The preparations used may
be therefore regarded as from individuals in good condition.
266 JOURNAL OF COMPARATIVE NEUROLOGY.
The muscle-nerve-cord preparation was made as in the other
members of this series. It was found after experimenting with
one specimen that the dissection of the cord for its whole length
produced too great injury to it, and such extended dissection is.
unnecessary. The cord is fairly free and easily accessible to
the electrodes. No precaution against its breaking itself in
pieces is necessary with the leech. Unfortunately, the dis-
section necessary to make the preparation caused the posterior
portion of the animal to contract so strongly that it would not
react to further stimulus and hence could not be used to make
records of contractions. Consequently we were unable to de-
termine the antero-posterior rate in the cord. The head end,
however, being free from this prolonged contraction allowed
the determination of the postero-anterior rate. This was not
without difficulties, for the almost incessant motion of the an-
terior part of the animal, thus continually displacing the lever
attached to it, makes it necessary to watch very closely to catch
the moment of rest of the animal, coinciding with proper ad-
justment of apparatus. Still, when all was right, the stimulus
gave prompt and decisive reaction. These conditions made it
obviously impossible to take the records at equal intervals.
It was found necessary to make use of the interrupted cur-
rent, for, while single induction shocks were efficient as a stim-
ulus when applied at the point of the cord nearest the muscula-
ture used, they failed to produce a definite contraction when ap-
plied at the distal point. This was true for both directions in
the cord. However, a single induced shock applied to a point
in the posterior end of the cord generally produced the indefi-
nite motion of swimming or crawling.
At the conclusion of each experiment the worm was killed
in 5% alcohol, the cord dissected out, and measured after tak-
ing the precaution to straighten out the loops formed in the in-
terganglionic portions produced by the contraction of the body
of fhe leech
The temperature of the room varied from 16°C, to 21°C.
EXPERIMENT No. 2, Table II, Oct. 5, Igo1.
Distal Proximal
No. of records 23 23
Mean latent time 0.28 sec.| O.II sec.
Standard deviation 0.03 sec.| 0.004 sec.
Coefficient of variability .10 | .036
Length of cord: 10.25 cm. Rate: 59.4 cm. per sec.
JENKINS AND Carson, Nervous Impulse in Worms. 267
TABLE II.
Summary of experiments on Aulastomum lacustre.
Postero-anterior rate.
No. of No. of records Length of } ;
experiment Distal Proximal cord in cm. Rate in em.;
, ae i ah 10.50 42.0
2 23 23 10.25 59.4
3 i + 10.50 39.9
4 28 27 10.50 57-7
5 15 18 10.25 48.2
6 8 9 10.50 45.1
7 29 25 11.00 47.0
8 18 21 10.50 87-1
9 II 15 II.00 572
10 12 6 10.50 80.8
Il 26 16 II.00 91.3
12 16 19 11.00 Bye
13 18 26 10.50 52.5
Mean rate: 56cm. per sec.
Standard deviation: 16.
Coefficient of variability: ,28.
Cirratulus sp.
This species is very common at Pacific Grove where it is
found under the rocks and in their crevices throughout the lit-
toral zone. It reaches a length of fifteen to twenty cm. The
posterior portion of the body is very slender and fragile and too
DIDIPIPPPPPPPLPLIIIIPIPUIPPIPLIISPPLPPIPIPPLSPSPPSSPLPPP PPP IIPLPP PLP PPS IIIS PLP IP LL SL LI
Fig. 3. Cirratulus sp. Postero-anterior. Length of nerve cord between distal
and proximal electrodes: 9 cm. Rate: r00cm. persec. Time: 50 d.v.
per sec.
feeble to raise the lever of the apparatus, consequently the an-
tero-posterior rate was not determined. The head end, how-
268 JOURNAL OF COMPARATIVE NEUROLOGY.
ever, reacts well to stimuli to different points in the cord and
allows the determination of a postero-anterior rate. On first
making the preparation the head end contracts strongly, but in a
few minutes it relaxes, and afterwards the preparation is fairly
quiet, reacting only to the stimulus from the electrodes. A
single induced shock applied to a point in the posterior portion
of the cord usually produced contractions in its immediate vi-
cinity which extended a short distance only, not reaching the
head. However, a weak interrupted current of short duration
produced a contraction which reached the anterior end.
The preparations fatigue quickly, so that only a few com-
parable tracings can be obtained in each case.
The length of the nerve cord was measured in the prepara-
tions after being killed in fresh water.
EXPERIMENT No. 4, Table [II, postero-anterior, Aug. 16, 1901.
Distal Proximal
No. of records 3 3
Mean latent time 0.28 Sec. 0.17 sec
Standard deviation 0.009 sec. 0.01 sec.
Coefficient of variability .03 .05
Length of cord 10 cm. (105 segments). Rate: 90.9 cm. per sec.
TABLE III.
Summary of experiments on Czrratulus sp.
Postero-anterior rate.
No. of No. of records Length of :
. = . Rate in cm.
experiment Distal | Proximal cord in cm.
I 3 | 3 13 85.8
2 6 | 8 15 82.5
3 4 4 18 86.4
4 3 3 10 90:9
5 2 5 9 99.9
6 4 4 9.5 86.4
Mean rate: 90 cm. per sec.
Standard deviation: 1.66.
Coefficient of variability: .o13.
Arenicola sp.
This worm as judged by the number of its egg masses seen
during the breeding season is common in the vicinity of Pacific
Grove. However, the sand in which it lives is so filled with
large rocks that it is difficult to collect it. Only three work-
able specimens were obtained. It is very sluggish in its move-.
Ee
JENKINS AND CarRLson, Nervous Impulse in Worms. 269
ments. In attempting to make the nerve-cord-muscle prepara-
tion the musculature is thrown into strong and prolonged con-
traction. That of the circular musculature was the most marked
especially at the points where the worm was fastened to the
floor of the apparatus. This contraction of the circular muscu-
lature was so vigorous as to prevent the longitudinal muscula-
ture from shortening the body and thus acting on the lever. A
—_—________ NWN
LLLLIILISIGLIPIMISPISIIISSID IIS SDI IIIS SINIIISISILPIS SII
Fig. 4. Arenicola sp. Antero-posterior. Length of nerve cord between distal
and proximal electrodes: 10cm. Rate: 125 cm. persec. Time: 50d.v.
per sec.
dorsal longitudinal slit throughout the preparation did not les-
sen the effect of the circular contraction, but put the prepara-
tion in such a condition that the contraction of the longitudinal
layer on stimulation of the cord bent the preparation to the in-
ner side and in this way gave opportunity to attach the record-
ing lever. The nerve cord is about 0.7 mm. in diameter and
easily separated from the adjoining tissue. The interrupted
current was used, since single induction shocks proved inefh-
cient.
EXPERIMENT NO. 3, Table IV, antero-posterior, temp. 14.5°C, July 9, 1902.
Distal Proximal
No. of records 12 7
Mean latent time 0.20 sec. 0.12 sec.
Standard deviation O.OL sec. 0.007 sec.
Coefficient of variability 205 .06
Length of cord: tocm. Rate: 126 cm. per sec.
270 JOURNAL OF COMPARATIVE NEUROLOGY.
TABLE IV.
Summary of experiments on Avenicola sp.
Antero-posterior rate.
No. of No. of records Length of :
: Rance : Rate in cm.
experiment Distal Proximal cord in cm.
I 26 14 9 128.7
2 41 30 15 106.5
3 12 7 10 126.0
Mean rate: 120.6 cm. per sec.
Standard deviation: 9.
Coefficient of variability: .07.
Bispira polymorpha.
This large tube inhabiting worm is very abundant near the
lower limits of the tides. Their tubes are so well hidden in the
crevices of the rocks and so firmly attached to them, that it is
only with difficulty and great care that they can be removed
without injury to the occupants. When undisturbed the head
Fig. 5. Bispira polymorpha. Postero-anterior. Length of nerve cord be-
tween distal and proximal electrodes: 28 cm. Rate: 700 cm. per sec.
Time: 100 d.v. per sec.
of the worm with the mass of constantly moving tentacles is pro-
truded from the tube. On being disturbed it suddenly retracts
its head and tentacles into the tube. Conformably with its
mode of life, the musculature of the anterior portion of the
body is greatly developed, especially that of the longitudinal
JENKINS AND Car son, (Vervous Impulse in Worms. = 271
layer, while that of the posterior portion is comparatively little
developed and is feeble in its action. On the other hand, the
contraction of the anterior portion was quick and powerful,
readily lifting a weight of 1000 grams. Consequently while
the preparations allowed the determination of the postero-an-
terior rate in the cord, the antero-posterior rate was not ob-
tained.
On account of the difficulties in dissecting out the cord
and the chances of injury to it on approaching it through the
dorsal side, the nerve-cord preparation in this worm could not
be made in the same way as was done in the other worms. It
was treated as follows: The worm was pinned to the board dor-
sal side down; a longitudinal incision was made through the
body wall on each side about one mm. from the median line on
the vental side; this ventral strip was further freed from all con-
nection with the organs in the body cavity. This strip con-
taining the uninjured ventral cord was raised and placed on the
electrodes. While this method, used with care, kept the cord
uninjured, it presented the apparent disadvantage of placing a
comparatively large thickness of tissue between the cords and
the electrodes. This did not, however, prove of any disadvan-
tage, as vigorous responses were obtained from single break in-
duction shocks even on stimulation at the posterior point, when
the secondary coil was 24 cm. fromthe primary. The anterior
12 to 15 segments were used as the reacting portion, leaving
from 17 to 20 cm. of nerve-cord between the points of stimulation.
The lever was weighted with from 20 to 25 grams. Ai single
break induction shock produces a single prolonged contraction.
The preparation is not easily fatigued. Anaesthetics were
found not to be necessary. The length of the nerve used was
measured after the preparation was killed in fresh water. Their
length, thus killed, corresponds to that of the animals undisturbed
in the aquarium but freed from their tubes. In this condition the
worm is from 12 to 15 cm. shorter than than in its tube.
EXPERIMENT No. 10, Table V, postero-anterior, temp. 14°C, Jan. 2, 1902.
Distal Proximal
No. of records II 7]
Mean latent time 0.057 sec. 0.024 sec.
Standard deviation 0.0022 sec. 0.002 sec.
Coefficient of variability -04 .08
Length of cord: 20 cm. (150 segments). Rate: 606 cm. per sec.
272 JOURNAL OF COMPARATIVE NEUROLOGY.
TABLE V.
Summary of experiments on Bispira polymorpha.
Postero-anterior rate.
No of No. of records Length of ;
: SSS - Rate in cm.
experiment Distal Proximal cord in cm.
I 12 12 18 691
= x 2 15 555
3 2 2 18 817
4 15 16 20 | 952
5 16 15 19 729
6 11 II 17 629
7 8 8 20 714
8 4 2 20 | 526
9 6 4 17 680
10 1I 7 20 606
Mean rate: 694 cm. per sec.
Standard deviation: 93.
Coefficient of variability: .13.
Aphrodite sp.
An undetermined species, probably new, of this interesting
Polychete occurs in the vicinity of Pacific Grove. As it lives
in rather deep water and seems not to be common it is only oc-
casionally brought in by the fishermen. We have secured thus
- ne.
eee ee eee
a en mn Nee | ee
WU AAAAAAA
Fig. 6. Aphrodite sp. Antero-posterior. Length of nerve cord between distal
and proximal electrodes: 8cm. Rate: 52.8cm. persec. Time: 50 d.v.
per sec.
far but two uninjured specimens, the largest of which measured
12cm. in length and 5 cm. in breadth. This worm is very
slow in its movements and it was found to possess a rather low
irritability since single induction shocks failed to procure a re-
action when applied to the distal point of stimulation. The
JENKINS AND Car son, Nervous Impulse in Worms. 273
complicated dorsal structures of this worm together with the
powerful contractions on irritation contribute to render the
making of nerve-cord-muscle preparations difficult. The red
pigmented nerve cord is nearly free in the body cavity and
when the body is contracted the cord is thrown into loops,
which necessitated the taking the cord out and straightening it
before measuring the length involved. The musculature of the
posterior end was taken as the reacting portion, and the antero-
posterior rate only was determined. Although single induction
shocks were not efficient at the distal points of stimulation to
produce contractions in the longitudinal muscles of the reacting
portion, they were found to be sufficient to set up a progressive
movement of the setz from the point of stimulation posteriorly,
indicating that their neuro-muscular apparatus is more irritable.
This seemed to be further indicated by the fact that the animal
could be quite roughly handled without producing contractions
of the longitudinal muscles, while the sete reacted to the
treatment.
F.XPERIMENT No. 2, Table VI, antero-posterior, temp. 15°C, Jan. 19, 1902.
‘Distal Proximal
No. of records 25 18
Mean latent time 0.422 sec 0.26 sec.
Standard deviation 0.045 sec. 0.03 sec.
Coefficient of variability _ +10 SDE
Length of cord: 9 cm. (17 segments). . Rate; tees 25 cm. per sec.
ABER Vile
Summary of Experiments on Aphrodite sp.
Antero-posterior rate.
“No of. | po lawee a vecords. ; | Length ae e
experiment | Distal | Promina | cord in cm. ate In cm.
I 34 3 } 52.8
. Sade ee Ce, Nea ee ee
Average r: rate: 54-5 cm, per sec.
Polynoe pulchra.
This worm lives on the surface of the oral tentacles of the
large sea cucumber, folothuria californica, and in the mouth
cavity of the large key-hole limpet, Lacopzna crenulata, both of
which are common at Pacific Grove. This species of Polynoe
reaches a length of from 4 to5 cm. On account of the delicacy
of its structure the nerve-cord is exposed with some difficulty.
The worm also breaks in pieces very readily, neither chloralhy-
274 JOURNAL OF COMPARATIVE NEUROLOGY.
drate nor decapitation serving to quiet it. These obstacles
prevented our obtaining satisfactory records from more than two
specimens, although many specimens were attempted. The
preparation fatigues quickly and single induction shocks, unless
very strong, were not always efficient. Only the postero-an-
terior rate was determined. Another species of this genus,
Polynoe brevis, is common at Pacific Grove, but as it reaches
a length of only 2 or 3 cm. no records could be taken from it.
wal. BAN sc eae aa re
a I oe 2 ee ee
pal SPAS EEN NE PALL) a SRE Oot 2 UE eh ee
GVA LPALDMPSPSPPISSISSS SSIS ISIN III.
Fig. 7. Polynoe pulchra. Postero-anterior. Length of nerve cord between
distal and proximal electrodes: 3.5cm. Rate: 350 cm. per sec. Time:
50 d.v. per sec.
EXPERIMENT No. 1, Table VII, postero-anterior, temp. 13°C, Aug. 16, IgoI.
Distal Proximal
No. of records 2 2
Mean latent time 0.127 sec. 0.110 sec.
Standard deviation 0.004 sec. none
Coefficient of variability .03 none
Length of cord: 4 cm. (33 segments). Rate: 230 cm. per sec.
TABLE VII.
Summary of experiments on Polynoe pulchra.
Postero-anterior rate.
No. of No. of records Length of ’
: : : Rate in cm,
experiment Distal Proximal cord in cm.
I 2 2 4 236
2 2 2 3.5 350
Average rate: 293 cm. per sec.
Sthenelais fusca.
This worm seems to be rare at Pacific Grove. Satisfactory
records for a single specimen only were obtained, and these are
of the rate of the impulse in the postero-anterior direction.
JENKINS AND Carson, Nervous Impulse in Worms. — 275
pea OL Pa Ta) ae Fea Se eS
LIPOPPOMIALASILIIMIIIPIMSPPIPPLIPLIILIPICELIPIII IPL PL LIAL ILL III
Fig. 8. Sthenelats fusca. Postero-anterior. Length of nerve cord between
distal and proximal electrodes: 5 cm. Rate: 250 cm. persec. Time: 100
d.v. per sec.
TABLE VIII.
Detail of experiment on Sthenelats fusca. Dec. 31, 1902.
Postero-anterior.
Total latent time in sec.
Distal Proximal
.065 -025
045 .028
055 .028
-050 .029
O45 -028
.048 .025
Average: .O51 rch .027
Transmission time: 0.024 sec.
Length of cord: 5 cm. (53 segments).
Rate: 205 cm. per sec.
Eunice sp.
This worm, fairly abundant, lives under rocks in tubular
passages formed by cementing particles of gravel together. It
attains a considerable length, specimens 25 cm. long being
taken. It breaks into pieces very readily. For this reason,
and further, because of its violent struggling in being captured,
an unbroken specimen was rarely secured.
When being prepared for experimentation in the usual
manner, Eunice always broke in pieces unless it was previously
276 JOURNAL OF COMPARATIVE NEUROLOGY.
decapitated, but even the decapitated preparation would some-
times twist itself in two. Chlorhydrate had the same quieting
effect as decapitation.
Eunice is very quick in its movements and compares in ir-
ritability with Polynoe and Nereis. Single induced shocks were
efficient stimuli, the reacting portion responding generally with
a single prolonged contraction.
MIOPMPOLIIWIPPIIIMWIPPPPPPPPPIPIIPOPMIOS_PMVIIVPII PLC IIPIPLIOPPLILIPLLI LI IDID LIL III LIL DL
Fig. 9. Eunice sp. Postero-anterior. Length of nerve cord between distal
and proximal electrodes: 9 cm. Rate: 450 cm. persec. Time: 100 d.v.
per sec.
The measurements were made after the preparation had
been killed in fresh water, which gives nearly the same exten-
sion as when the worm is lying quiet in the aquarium.
The antero-posterior rate alone was determined.
EXPERIMENT No. 3, Table IX, postero-anterior, Dec. 26, 1902.
Distal Proximal
No. of records 13 12
Mean latent time 0.050 sec. | 0.038 sec.
Standard deviation 0.003 sec. | O 0023 sec.
Coefficient of variability .060 .061
Length of cord: 5.7 cm. Rate: 474.8 cm. per sec.
JENKINS AND Cartison, Nervous Impulse in Worms. 277.
TABLE IX.
Summary of experiments on Lunice sf.
Postero-anterior rate.
No. of No. of records Length of f
; Se 5 Rate in cm.
experiment Distal | Proximal cord in cm.
I 2 | 2 9 473-4
z 3 3 4.5 409.0
3 14 | 12 5-7 474.8
4 13 12 | 13.0 520.0
Mean rate: 466 cm. per sec.
Standard deviation: 41.
Coefficient of variability: .o9.
Nereis sp.
This species is very common at this point. It is found
under rocks and crevices, attaining a length of 15 cm. The
posterior third of the body is too weak and fragile to raise the
lever, hence the antero-posterior rate was not determined. Un-
less it was first decapitated the conditions of the experiment
invariably threw the worm into violent contractions by which
it broke into pieces. The activity and irritability of this worm
ee em tat
—EEEE—EE—EEEE
soe ee
VWAWIIIIJIAIIJIJIJIJIJIJIJIJIJIIIJVIJIIJIJIIWIPIPTIIIJSIIISP IS SINSNINSNINAISSIIS-
Fig. ro. Nereis sp. Postero-anterior. Length of nerve cord between distal
and proximal electrodes: 12 cm. Rate: 133.2 cm. persec. Time: 50
d.v. per sec.
is much the same as that of Eunice and Glycera. However it
does not respond to single induction shocks as regularly as
does Glycera. A single shock applied to the cord posteriorly
produces a contraction anterior to the point of stimulation, the
distance to which the contraction extends depending on the in-
tensity of the stimulus. Still, the contraction does not always
reach the head even with a high intensity of stimulus. The
interrupted current is more sure of producing this effect.
278 JOURNAL OF COMPARATIVE NEUROLOGY.
The length of nerve-cord between the points of stimulation
was measured after the preparation was killed in fresh water, in
which the condition is very near the normal extension of the
worm.
EXPERIMENT NO. 2, Table X, postero-anterior, Aug. 7, Igor.
Distal Proximal
No. of records 8 9
Mean latent time 0.095 sec.| 0.061 sec.
Standard deviation 0.003 sec. | 0.0046 sec.
Coefficient of variability .031 -075
Length of cord: 55 cm. (45 segments).
Rate: 165 cm. per sec.
TABLE X.
Summary of experiments on WVerezs sp.
Postero-anterior rate.
No. on ie No: of records Length of ’
j : ; : Rate in cm.
experiment Distal Proximal cord in cm.
1 A 4 4 10.0 164
2 8 8 5:5 165
31 9 9 12.0 223-2
4 3 3 5-0 156.0
5 4 4 120 | 123.6
Mean rate: 165 cm. per sec.
Standard deviation: 32.
Coefficient of variability: .19.
Nereis virens Sars (=N. branti Ehlers).
This species seems to be quite rare at Pacific Grove, since
but one specimen was secured during extended collecting in
the summers of 1901 and 1902. The specimen was about 100
cm. in length and from 1 to 1.5 cm. in diameter, but it unfor-
tunately broke into several pieces through its contractions when
being captured and the piece containing the head, which was
the largest, broke up further in attempting to submit it to the
experimental conditions. Decapitation served to quiet its mo-
tions, and, no doubt, a much. longer portion could have been
obtained if this treatment had been used at first. The ventral
cord was from I mm. to I.5 mm. in diameter, which large size
together with its favorable position in the body allowed it to be
easily dissected free. Two pieces were used, one with the
head contained 85 segments and gave an available distance of
cord of 20cm. The other was from near the tail and con-
tained 25 segments with 6.5 cm. of cord available. These dis-
JENKINS AND Carson, WVervous Impulse in Worms. 279
tances were measured while the pieces were crawling in the
aquarium and represent very nearly the length during the nat-
ural extension of the worm.
Single induction shocks applied to the distal point of
stimulation produced a single prolonged contraction. After
three or four reactions, single shocks failed at the distal
point, then the break or make of the direct current was still
efficient. Since the largest preparation was no more than one-
fourth the length of the whole worm, it is impossible to say
whether through the whole length of the cord a single induc-
tion shock would prove efficient.
ame en mn PGS
Dee
ae INN ee
SLPLISLPPPPFSSL PS LPGPPLSP SPP SSISLS SPS SPSS IVS SLI ISI III
Fig. 11. Nere/s virens. Antero-posterior. Length of nerve cord between dis-
tal and proximal electrodes: 6.5 cm. Rate. 81.2 cm. persec. Time: 56
d.v. per sec.
Good reactions were obtained from one portion 24 hours
after its separation from the rest of the body; in other pieces
48 hours later only feeble responses were obtained; however
one piece lived three weeks in the aquarium, when it was de-
stroyed by an accident. In one piece the rate was taken in the
antero-posterior direction, in the other postero-anterior direc-
tion. The rates 89 and 73.4 respectively, differing as they do,
may not be taken, in the absence of other experiments, as con-
clusive evidence that the rates in the two directions differ.
EXPERIMENT No. 1, Table XI, antero-posterior, July 20, 1901.
Distal | Proximal
_— - | = -
No. of records 27 ES
Mean latent time 0.183 sec. 0.096 sec.
Standard deviation 0.016 sec. 0.007 sec.
Coefficient of variability .08 Or
Length of cord: 6.5 cm. (25 segments).
Rate: 73.4 cm. per sec.
280 JoURNAL OF COMPARATIVE NEUROLOGY.
TABLE Xi.
Summary of experiments on Nereis virens.
No. of | No. of records Length of :
s : Rate in cm.
experiment Distal | Proximal cord in cm.
I |
(antero-posterior) | 27 | Ig 6.5 73-4
5 |
(postero-anterior) | 13 | II | 20.0 | 89.0
Lumbriconereis sp. (a).
Small specimens of this species of 20 to 30 cm. and from
2 to 3 mm. in diameter are very abundant in the gravel at the
lower limits of the tide, but only one large specimen was se-
cured. This was 75 cm. in length and from 6 to 7 mm. in di-
ameter, but the specimen was accidentally broken in two pieces
in being captured. The anterior portion proved of great ser-
vice since since 150 good records distributed over a period of
three days were obtained from it. The posterior portion failed
WIVWVYIIJIIIIIVIYJYAPJIPIPIWIIVIIVIJIJIJI(II{IIIIIIIJPIPAIIPADIIIIIN
Fig. 12. Lumbriconerets sp. (a) Postero-anterior. Length of nerve cord be-
tween distal and proximal electrodes: 21cm. Rate: 262.5 cm. per sec.
Time: 50 d.v. per sec.
to give equally good results from the fact that in attempting to
prepare it for experimentation it went into a strongly contracted
state which continued for three days, although left undisturbed
in the aquarium. During this time it failed to react to any
stimuli. This same phenomenon has been observed in some of
the specimens of Glycera which had been injured. The smaller
specimens of Lumbriconereis gave so much trouble in this way
that but few records were obtained from them. These are the
only free swimming polychetes in which this phenomenon was
observed.
JENKINS AND Carson, Nervous lmpulse in Worms. 281
The nerve-cord-muscle preparation can more easily be
made from Lumbriconereis than from Glycera on account of its
squirming less. Like Glycera, it is less easily broken than the
rest of the series worked with. It is less active than Glycera
but equally irritable; single induction shocks applied to the cord
20 cm. from the reacting portion produce good contractions.
The measurements of the cord were taken after killing the prep-
aration in fresh water.
EXPERIMENT No. 1, Table XII, postero-anterior, July 24 to 27, 1goOl.
Length of cord: 21 cm. (114 segments).
July 24 First four pairs of records, rate: 300 cm. per sec.
3-9 p- m, Total No. of records (24 pairs), rate: 65 cm. per sec.
July 25 First four pairs of records, rate: 221 cm. per sec.
8-11 a.m. Total No. of records (16 pairs), rate: 65 cm. per sec.
July 25 First three pairs of records, rate: 210 cm. per sec.
4-6 p. m. Total No. of records (15 pairs), rate: 94 cm. per sec.
July 26 First three pairs of records rate: 233 cm. per sec.
ga.m.-5 p.m. Total No. of records (13 pairs), rate: $0 cm. per sec.
July 27 First pair of records, rate: 42 cm. per sec.
ga. m.
The coefficient of variability of the transmission time of the fourteen pairs
of records that show a rate above 200 cm. per sec, is .37.
TABLE XD.
Summary of experiments on Lumbriconerets sp. (a)
Postero-anterior rate.
No. of | No. of records | Length of ;
- aa = = : Rate in cm.
experiment Distal Erosimal cord in cm.
I | 14 14 | 21 241
2 3 | 3 | 9 45
eee, 4 4 10 45
Lumbriconereis sp. (b)
This worm is very abundant in crevices and under rocks
where it constructs for itself delicate tubular passages by debris
and gravel cemented together. It is commonly 30 to 40 cm.
in length and from 5 to 7 mm. in diameter, but owing to its
great fragility generally only portions of the worm could be se-
cured for the preparation. The worm is rather inactive, so
anesthetics were not necessary. Despite its sluggish habits it
responds to single shocks almost as readily as Glycera, but the
282 JoURNAL OF COMPARATIVE NEUROLOGY.
preparation fatigues much sooner. The measurements of the
cord were made on preparations killed in fresh water, with the
exception of preparation No. 7, Table XIII A., which was ex-
tended during the experimentation to the length given.
ah a
Be EEE OOO OeOOEeeeeeeeeeeeesees@9s@s—_” reo
oT EEE ESSE
Fig. 13. Lumbriconerets sp. (b) Postero-anterior. Length of nerve cord be-
tween distal and proximal electrodes: 30cm. Rate: 681 cm. per sec.
Time: 100 d.v. per sec.
EXPERIMENT No. 4, Table XIII, postero-anterior, Aug. 7, 1902.
Distal Proximal
No. of records 6 6
Mean latent time 0.060 sec. 0.035 sec.
Standard deviation 0.004 sec. 0.004 sec.
Coefficient of variability -O7 at
Length of cord: 15 cm. (125 segments). ‘Rate: 600 cm. per sec.
TABLE XIII A.
Summary of experiments on Lumértconereis sp. (b)
ustero anterior rate.
No. of No. of records _ Length of ,
i . Rate in cm.
experiment Distal Proximal cord in cm.
I 4 2 20 40
Z 5 3 13
3 3 3 16
4 6 6 | 1)
5 4 4+ | 12 52
6 5 5 15 937
7 9 8 30 768
JENKINS AND Carison, Nervous Impulse in Worms. 283.
TABLE XIII B.
Summary of experiments on Lumbriconerets sp. (b)
Antero-posterior rate.
No. of No. of records | Length of )
experiment Dista Proximal cord in cm. Rate in cm.
: a) 4 25 ; 80
2 3 3 8 160
3 2 fe) 42
Glycera rugosa Johnson.
This worm is fairly abundant in the sands of the lower tide
limits at Pacific Grove. The largest specimen that we collected
measured from 35 to 40 cm. in length and about 13 mm. in diam-
eter, when killed in fresh water. It is very ferocious, even in the:
aquaria preying on Eunice and Nereis. It is also very active,
ROR igs FNS a th a ce RRO ae ge A la WS er A Se
NAA
fig. 14. Glycera rugosa. Antero-posterior. Length of nerve cord between
distal and proximal electrodes: 30cm. Rate: 441 cm. per sec. Time: 50
d.v. per sec.
making its way through the wet sand with great speed or glid-
ing through the water by the graceful twistings of its whole
body. This worm was selected for a beginning in this work
because of its large size, high irritability and strength. Glycera
is less fragile than any of other free swimming polychetes
worked excepting Lumbriconereis sp. (a) which equals it in
this respect.
284 JOURNAL OF COMPARATIVE NEUROLOGY.
In most cases an anaesthetic, chlorhydrate, was necessary to
quiet the violent squirming in making the preparation. De-
capitation did not quiet these motions. The preparations re-
sponded with great regularity to single induction shocks of
moderate intensity applied to the cord 20 to 30 cm. from the
contracting portion; when the single shock became inefficient
the interrupted current of short duration was used. The nerve-
cord-preparation of this species is not easily fatigued and conse-
quently allows a great number of records to be taken from each
specimen. The preparation from one specimen, No. 2, Table
XIV A, gave good responses 23 hours after it was made.
It frequently happened that an injury to any part of the
body caused the musculature, both circular and longitudinal, to
go into a strongly contracted state, in the immediate region of
the injury. This condition in some cases continued for 24
hours, or even more, during which time it is practically impos-
sible to send an impulse through the cord of the contracted
portion. In the only case in which an impulse passed through
so small a distance as 100 segments of the worm a strong inter-
rupted current was necessary. Even in this case the respond-
ing contractions were feeble and very much delayed.
EXPERIMENT No. 2, Table XIV A, postero-anterior, July 16, 1901.
Distal | Proximal
No. of records 32 32
Mean latent time 0.18 sec. 0.10 sec.
Standard deviation 0.014 sec. 0.003 sec.
Coefficient of variability .08 .03
Length of cord: 34 cm. (150 segments). Rate: 425 cm. per sec.
TABLE XIV A.
Summary of experiments on Glycera rugosa.
Antero-posterior rate.
No. of | No. of records Length of | ;
. ; | Rate in cm.
experiment \ Distal Proxima! cord in cm. |
I | 21 22 34 680
2 | 33 32 34 | 425
3 II Il 25 357
4 22 22 20 ‘400
5 4 | 4 25 500
6 | 25 25 17 425
7 | II 11 20 400
8 12 Il 30 375
9 9 9 24 | 271
Mean rate: 433 cm, per sec.
Standard deviation: 87.
Coefficient of variability: .20.
JENKINS AND Carson, Nervous Impulse in Worms. 285
TABLE XIV B.
Summary of experiments on Glycera rugosa.
Postero-anterior rate.
No. of No. of records Length of ‘
: : Rate in cm.
experiment Distal | Proximal cord in cm.
ear ve | i | 7 15 | 420
2 2 2 18 | 514
3 | 7 | 7 13 540
ee NTs i aE 18 | 265
Mean rate: 435 cm. per sec.
Standard deviation: 106.
Coefficient of variability: .24.
TABLE XV.
Summary of the rates in the fourteen species worked on.
ki é _. | Coeff
Species Direction Race ks cient of
individuals | in cm. Res
vari’ bility
Cerebratulus sp. Postero-anterior 2 5-4-9.0 ah
Aulastomum lacustre oe oe 13 56.0 .28
Cirratulus sp. ag ne | 6 | go-0) |) :01g
Arenicola sp. Antero-posterior 3 eu 2O208s oy
Bispira polymorpha Postero-anterior IO 6940 | .13
Aphrodite sp. Antero-posterior 2 54-5 .04
Polynoe pulchra Postero-anterior 2 293-0 | .19
Sthenelais fusca ne ye | I 205.0
Eunice sp. ae < | 4 466.0 .09
Nereis sp. se ck 5 165.0 .19
Nereis virens at a I 89.0 |
Ge oe Antero -posterior I 73-4
Lubriconereis sp. (a) |Postero anterior 2 45-241
ef * (Bb) a oe 7 49-937
ae «« (b) |Antero-posterior 3 42-160
Glycera rugosa Ob SS 9 433-0 .20
. ck Postero-anterior 4 435-0 24
page 268), Bispira (table V, page 272), Eunice (table IX, page
277), Nereis sp. (table X, page 278), and Glycera (table XIV,
page 284), the number of individals worked and the relative
constancy of the individual rates seem to allow the conclusion
that the mean of the individual rates is representative for their
respective species. The mean in the groups represented by
by two or three individuals only is of less value, especially in
the two species of Lumbriconereis (tables XII and XIII) where
the individual variations are so great. But in some species
286 JOURNAL OF COMPARATIVE NEUROLOGY.
thus scantily represented the individual rates show only slight
variation, as in Arenicola (table IV, page 270), Aphrodite (table
VI, page 273), Polynoe and Sthenelais (tables VII and VIII,
pages 274 and 275), and Nereis virens (table XI, page 280), and
their representative means may therefore not be far from the
true rate in these species.
The rate of the nervous impulse in this series of worms is
as varied as the structure and the habit of the worms them-
selves, the lowest being in Cerebratulus with a rate of only 5 to
g centimeters per second and the highest in Bispira with a rate
of 7 meters persecond. But there seem also to be differences
in rate between species in which little difference in structure
and habits exists, as in the cases of Eunice and Nereis (tables
IX, X and XI), the former showing a rate of 466 cm. per sec-
ond, the latter a rate of 165 cm. per second.
In the species which permitted of determining the rate of
the impulse in both directions of the cord (Nereis, table XI;
Lumbriconereis, table XIII, and Glycera, table XIV) there
seems to be no constant difference between the antero-posterior
and the postero-anterior rates. :
A question of considerable interest is whether the rate in
the ventral nerve cord as determined in the present work repre-
sents the rate through continuous nerve fibers as in a verte-
brate muscle-nerve preparation or whether the nervous paths.
are more complex. Our knowledge of the structure of the
ventral nerve cord of the worms has been greatly advanced
within the last few years through the researches of RETZIUs.
(10, 1891, 1892, 1894, 1898, 1g00), Ruope (11, 1891), Brep-
ERMANN (12, 1891), LENHOSSEK (13, 1892), FREIDLANDER (14,
1894), ApAruy (15, 1897) and Haver (16, 1899). But while
many of the histological elements have thus been worked out and
found to be markedly uniform throughout the phylum, it seems
that the number of segments with which a motor neuron comes.
in direct relation and the extent and relation of the small sen-
sory fibers in the longitudinal tracts and of the central or ‘‘as-
sociation cells’’ are yet undetermined. Even the applicability
of the neuron conception to the nervous system of the worms
JENKINS AND Carson, Nervous Impulse in Worms. 287
is called in question by ApAtTuy’s work. On histological
grounds we cannot therefore say whether the ventral nerve cord
contains such a direct nervous path extending throughout its
whole length.
Nor does the present work furnish anything conclusive on
this point. It is true that the muscle-nerve-cord preparations
of Bispira, Glycera, Eunice, Nereis and Lumbriconereis re-
spond to a single induced shock of low intensity ; and these re-
sponses on stimulating the cord 20 to 30 cm. from the muscle
in Bispira and Glycera approached the uniformity of the re-
sponses of the frog’s gastrocnemius on stimulation of the sciatic
nerve. And such uniformity in the response to single induced
shocks has not been found to obtain in the vertebrates when
complex nervous mechanisms are involved. On the other
hand, such great variation of the rate in the same preparation as
was observed in Lumbriconereis (page 281) can not be recon-
ciled with the physiology of simple muscle nerve preparations
as it is known in vertebrates and molluscs. In Cerebratulus,
Aulastomum, Cirratulus, Arenicola, and Aphrodite the muscu-
lar response to a single induced shock applied to the nerve cord
subsides few centimeters in either direction from the point of
stimulation. It requires a series of shocks to obtain the mus-
cular response if the length of nerve cord involved comprises
many segments; which fact suggests a complex nervous path.
But while the response of the nerve cord toa single induced
shock points in some species to a complex, in others to a sim-
ple nervous mechanism, the question remains yet undecided
whether in the latter cases the nervous part of the muscle-nerve-
cord preparation is as simple as that of an ordinary muscle-
nerve preparation.
It is of some interest to know that the lowest rate in the
Annelids, that of Aphrodite, or 54 cm. per sec., is higher than
the rate in the pedal nerve of the slug, Ariolimax, which we
found to be 40 cm. per sec., while the rate in Glycera (430 cm.
per sec.), Eunice (460 cm. per sec.) and Bispira (694 cm. per
sec.) is as high and even higher than the rate in the pallial
nerve of the swift moving Loligo (17, 1903).
288
Ue
10.
JOURNAL OF COMPARATIVE NEUROLOGY.
LIST OF PAPERS CITED IN, THE TEXT:
Biedermann, W.
Zur Physiologie der glatten Muskeln. Archiv fiir die gesamte Phystolo-
gie, XLVI. 1889.
First M.
Zur Physiologie der glatten Muskeln. Archiv fiir die gesamte Phystolo-
gie, XLVI. 1889.
von Uexkill, J.
Zur Muskel- und Nerven- physiologie von Sipunculus nudus. Zettschrift
fiir Biologie, XX XIII. 1896.
Bottazzi, Ph.
Contributions to the Physiology of Unstriated Muscular Tissue. /oxurnal
of Physiology, Vol. XXII. 1898.
Straub, W.
Zur Muskelphysiologie des Regenwurms. Archiv fiir die gesamte Ph ys-
zologie, LXXIX. 1900.
Buddington, R.A.
Some Physiological Characteristics of Annelid Muscle. American Jour-
nal of Physiology, Vol. VII. 1902.
Loeb, J.
Beitrage zur Gehirnphysiologie der Anneliden. Archiv fiir die gesamte
Phystologie, XVI. 1894.
Friedlander, B.
Beitrage zur Physiologie des Centralnervensystems und der Bewegungs-
mechanismus der Regenwiirmer. Archiv fiir dte gesamte Physiologie,
LXVIII. 1894.
Maxwell, S.
Beitrage zur Gehirnphysiologie der Anneliden. NERVE-
FIBERS.
By OLIvER S. STRONG,
Columbia University, New York.
The following is not the outcome of a systematic investi-
gation of the technique of the method of WeiGeErtT, but simply
of experiments made at various times to secure the best results
on material hardened as described below. Notes were often
made which have been collated and the conclusions pre-
sented, not so much as invariable improvements on the regular
procedure, but as suggestions for securing better results in cer-
tain cases. Inthe estimation of the success of a WEIGERT
preparation, especial weight has been attached to the number
of fibers revealed in the gray and the brilliancy with which they
are demonstrated.
The material consisted of portions of the central nervous
system, especially the cord, of the human foetus, infant and
adult. This.material was fixed in formalin, in potassium bichro-
mate and formalin, or in copper bichromate. The fixation in
formalin was usually accomplished by injecting into the blood
vessels formalin I vol. + water several volumes. After re-
moval the brain and cord were kept in formalin 1 vol. +
water g vols. until used. Some material which yielded fine
preparations had been thus kept in formalin for three years.
The material fixed in potassium bichromate and formalin was
usually fixed by an injection zz sztu of potassium bichromate
5%, or stronger, several vols. + formalin 1 vol. After removal,
the cord and portions of brain were further hardened in potas-
sium bichromate 5 % g vols. + formalin 1 vol. about a week and
in potassium bichromate 5% alone for ten days to 2 weeks or
so. Finally, some material, the brain and cord of a 7 months
292 JOURNAL OF COMPARATIVE NEUROLOGY.
foetus, was fixed by injection zz sztu of copper bichromate 5 %
1 vol. + formalin 1 vol and further hardened, after removal, in
copper bichromate 3% 9g vols. + formalin 1 vol. for about a
week. A method pursued with some selachian material for the
study of the cranial nerves will be described below.
In order to give an idea of the various combinations of
mordanting and decolorizing tried upon the above material a
condensed list is given below together with the general charac-
ter of the results. The staining fluid used was either WEIGERT’S
alkaline haematoxylin (abbreviated in the list to ‘‘A. h.”’) ora
neutral haematoxylin solution composed of 1 vol. of 10% solu-
tion of haematoxylin in absolute alcohol + g vols. of water
(‘‘N. h.”’). Where the kind of haematoxylin solution used is
uncertain the abbreviation is ‘‘H.’’ The word ‘‘osmic”’ indi-
cates that the section was placed in osmic acid. When this was
done after the removal from the haematoxylin the section was
simply rinsed in water, placed in 4% % + solution of osmic acid
for 4% to I minute and then rinsed again in water, previously to
decolorization.
A. Celloidin sections of material (principally cord of infant and of
eight months foetus) fixed and hardened in potassium bichro-
mate + formalin as above described :
Copper acetate. A.h. Pal. Failure.
2.. Copper acetate. A. bh.; H. and N. h. Osmic. Pale iia.
sults often good, in some cases fine preparations.
3. Copper acetate. Osmic. A. h. Pal. Not very good.
4. Copper acetate. Osmic. A. h. Osmic. Pal. Fine results.
5. Copper acetate. H. Borax-ferricyanide. Not very good
results—distinctly inferior to the Pal.
6. Copper acetate. H. Osmic. Borax-ferricyanide. Some-
what better than 5.
7. Copper bichromate. A.h. and N. h. Borax-ferricyanide.
Not good.
8. Copper bichromate. H. Pal. Good.
Copper bichromate. H. Osmic. Pal. Very good. This
gave the best results of any combination.
to. Copper bichromate. N.h. Ironalum. Failure.
11. Copper bichromate-+ osmic. A. h. Pal. Failure.
Lal
12.
ee
14.
Le
16.
Ea:
18.
19.
20.
20.
22.
2ae
24.
25
2Ge
ay
Blocks of tissue, hardened like A, imbedded in celloidin, mor-
StronG, Technique of Weigert’s Method. 293
\
Copper bichromate. Potassium bichromate + osmic. H.
Pal. Not good.
Iron alum. A.h. Ironalum. Failure.
Iron alum. H. Osmic. Pal. Failure.
Iron alum. H. Borax-ferricyanide. Failure.
Iron alum. Potassium bichromate + osmic. H. Pal.
Failure.
Potassium bichromate. A.h. and N.h. Pal. Not good.
Potassium bichromate. A.h. Borax-ferricyanide. Not good.
Potassium bichromate. Iron alum. H. Borax-ferricyanide.
Fair.
Potassium bichromate. Iron alum. H. Osmic. Pal. Good.
Potassium bichromate. Iron alum. H. Pal. Not good.
Potassium bichromate. fron alum. H. Iron alum. Failure.
Potassium bichromate + chrome alum. H. Pal. Not good.
Potassium bichromate ++ chrome alum. H._ Borax-ferri-
cyanide. Failure.
Potassium bichromate. Copper acetate. N.h. Osmic. Pal.
Fair.
Potassium bichromate. Copper acetate. N. h. Borax-
ferricyanide. Failure.
Potassium bichromate + osmic. N. h. Pal. Not good.
danted z” fofo in copper bichromate several days. The sec-
tions made were then treated as follows:
ive
2.
3-
A. h. (at higher temperature part of time) Osmic. Pal.
Fine.
A. h. (at higher temperature part of time.) Pal. Not very
good, lacking in brilliancy.
A. h. (at higher temperature part of time.) Borax-ferri-
cyanide. Failure.
C. Cord of a seven months foetus hardened in copper _ bichro-
IEA PW N
mate ++ formalin as above described. The celloidin sections
made were treated as follows :
- Calcium bichromate (5%, 13 days). A. h. Osmic. Pal. Fine.
Copper acetate. H. Pal. Net good.
Copper acetate. H.Osmic. Pal. Good.
Copper acetate. H. Borax-ferricyanide. Failure.
Copper bichromate. H. Borax-ferricyanide. Not good.
Copper bichromate. H. Osmic. Pal. Good.
No further mordanting. H. Osmic. Pal. Good. These
204
JouRNAL OF ComPaARATIVE NEUROLOGY.
preparations were in many cases practically as good as
those that were re-mordanted, there being only a slight
diminution in the intensity of the stain.
D. Cerebrum of infant. Hardened in formalin as described above.
Imbedded in celloidin without mordanting. Sections made
were treated as follows:
I
Copper acetate 46 hours. A.h.1% hours. Osmic. Pal.
Not good, fibers very pale.
Copper acetate 46 hours. A.h.1% hours. Borax-ferri-
cyanide. Not good.
Copper bichromate 46 hours. A.h.1% hours. Osmic.
Pal. Not good. Somewhat better than 1.
Copper bichromate 46 hours. A.h. 1% hours. Borax-
ferricyanide. Not good.
Copper bichromate 46 hours. A.h 1% hours. Osmic.
Borax-ferricyanide. Not good.
Copper bichromate 46 hours. A.h. 47 hours. Osmic.
Pal. Better than any of preceding.
Copper bichromate 46 hours. A.h. 23 hours. Osmic.
Pal. Like 6.
Copper bichromate 46 hours A.h. 23 hours. Borax-
ferricyanide. Not good.
Even the best of the above were too pale, perhaps partly,
but hardly principally, attributable to the youth of the
brain.
E. Cord and medulla of infant 1% months old. Hardened in form-
alin as above described. Pieces mordanted i” foto,
immediately after removal from formalin, in copper
bichromate 3% for seven or eight days. Imbedded in
STEPANOW’S Clove oil celloidin.!
Sections were treated as follows:
No further mordant. A.h. 12 hours. Osmic. Pal. Good.
No further mordant. N.h. 16 hours. Osmic. Pal. Very
good. .
Copper bichromate 4 hours. N.h. 15 hours. Osmic. Pal.
Very fine, better than 1 and 2.
Copper bichromate 18 hours. N.h. and A. h. 6 hours.
Osmic. Pal. Slightly inferior to 3.
1 Zeitschrift fiir wiss. Mikroskopie, BA. XVII, H 2, 1900.
StronG, Technique .of Wergert's Method. 295
5. Copper bichromate 18 hours. N.h., kept slightly warmed,
2to4 hours. Osmic. Pal. Very fine, possibly some-
what better than 3.
F. Cord, medulla and basal ganglia of child 3 years and 44% months
old. Hardened in formalin as above described and pre -
served in formalin for about three years before being
used.
(a) Pieces of cord mordanted in copper bichromate 3% seven days.
Imbedded in clove oil celloidin. Sections treated as
follows :
1. No further mordanting. H. Osmic. Pal. Good.
2. Copper bichromate. H. Osmic. Pal. Better than 1.
3. Potassium bichromate-+ osmic. H. Osmic. Pal. Not good.
(2) Pieces of cord mordanted in potassium bichromate + osmic.
Sections made as in (a) and treated as follows:
1. No further mordanting. H. Osmic. Pal. Much better
than (a2) 3 but not nearly as good as (a2)1 or 2. Med-
ullary sheaths of large fibers appear to be better fixed,
however, than in (a).
2. Potassium bichromate +osmic. H. Osmic. Pal. Better
than (6) 1.
3. Copper bichromate. H.Osmic. Pal. Very good, not so
brilliant as (a) 2 but the fibers, especially in the white
matter, look better than in (a).
(c) Pieces of cord mordanted seven days in potassium bichro-
mate 5 + chrome alum 2+ water 100. Sections made
as in (a):
1. No further mordanting. H.12 hours. Osmic. Pal. Fair.
(a2) Pieces of cord mordanted seven days in potassium bichro-
mate 5%. Sections made as in (a).
1. No further mordanting. H.12 hours. Osmic. Pal. Not
as good as (c).
(ec) Pieces of cord mordanted seven days in copper bichromate
3%. Sections made as in (a).
1. No further mordanting. H.12 hours. Osmic. Pal. Fair,
a little better than (c).
(f) Pieces of cord mordanted seven days in potassium bichro-
mate + osmic. Sections made as in (a).
1. No further mordanting. H.12 hours. Osmic. Pal. Fair.
(g) Pieces of cord mordanted seven days in iron alum 4%.
Sections made as in (a).
296 JOURNAL OF COMPARATIVE NEUROLOGY.
1. No further mordanting. H. 12 hours. Osmic. Pal. Not
good.
(A) Pieces of cord mordanted eight days in copper bichromate.
Sections made as in (a).
1. No further mordanting. H.Osmic. Pal. Fair.
2. Copper bichromate several hours (kept slightly warmed).
H. 22 hours (first half hour in paraffine water-bath).
Osmic: Pal. ‘Fine.
3. Potassium bichromate-+ osmic several hours, etc., like 2.
Not good, blurred and indistinct.
{| (c) to (A) inclusive, taken from some incomplete notes made by
my student, C. E. Doran].
(¢) Pieces of medulla and basal ganglia mordanted 7” fofo in
copper bichromate 3% for seven or eight days. Sec-
tions made as in (a).
1. No further mordanting. N. h. 12 hours+Osmic. Pal.
This invariably yielded fine results with a series extend-
ing through the medulla and basal ganglia, practically as
good as when remordanting in section was resorted to
and without the added danger of brittleness.
The following modification of the WeEIGERT method was
devised by the writer in 1897 and has been found to be espec-
ially adapted for his work upon the cranial nerves of Squalus
acanthias. The head of an embryo at birth, cut longitudinally
vertically in two pieces so as to just open one side of the cranial
cavity, was hardened for about two weeks in iron alum 5%
g vols. + formalin 1 vol. This fluid also decalcified. Although
the material was somewhat brittle, a complete series of paraffine
sections was successfully made. After fixing on the slide and
successive removal of the paraffine and xylol, the slides were taken
from the absolute alcohol and a thin solution of celloidin poured
over them and off, thus covering the sections with a thin film
of celloidin and absolutely preventing their removal from the
slide during subsequent manipulations. This device, which had
been used by the writer for some time previously to this, very
much minimizes the danger of loss in staining serial paraffine
sections.
The sections were then stained, without further mordant-
StronG, Technique of Weigert's Method. 297
ing, in the above-mentioned neutral haematoxylin for 4 to 12
hrs., the shorter period being found sufficient. As in all WeEI-
GERT methods, old or used solutions of haematoxylin must be
avoided. The sections are then decolorized in 1% or 2% iron
alum, the decolorization proceeding slowly and evenly. With
any degree of care, over-decolorization is easily avoided. After
decolorization, the sections, now being a faint pinkish hue, are
washed, dehydrated, cleared and mounted.
With this method the peripheral nerves in Squalus were well
fixed and stained deep blue. The color was completely removed
from all other tissues except the denticles and sometimes por-
tions of cartilage. The central nervous system was not as well
fixed nor stained, but presented a fairly good WEIGERT picture.
The decalcifying power, simplicity and certainty of this
method recommend it for such work. The tendency of the
iron alum-formalin to overharden and make the tissue difficult
to section is perhaps the principal defect. With the loose tis-
sues of the young shark this objection was not realized as it
would be with other objects.
This method has been reported by Herrick (State Hos-
pitals Bulletin of N. Y. State, Oct., 1897, p. 27 and Journal of
Comparative Neurology, Vol. VIII, Nos. 1-2, July, 1898.).
Conclusions. Though many of the combinations in the
above lists have not been sufficiently tested, yet from these data
and from other observations of the writer, the following con-
clusions which may in cases be of practical value may be
drawn.
(2) Fixation and hardening in formalin alone appears to be
preferable in some respects to fixation and hardening in potas-
sium bichromate + formalin followed by further hardening in
potassium bichromate. The latter method is capable of yielding
fine preparations, but at times it appears difficult to secure them
by the ordinary procedures. Furthermore. in such material
the medullary sheaths when stained often exhibit a vacuolated
appearance, due apparently toa staining of the neurokeratin
network, which detracts from the brilliancy of the preparations.
.298 JOURNAL OF COMPARATIVE NEUROLOGY.
It is a question whether the plain bichromate fixing and harden-
ing be not superior in some regards.
(0) Formalin fixed and hardened material will apparently
keep indefinitely in formalin and yet be capable of giving fine
WEIGERT preparations when subjected to the appropriate treat-
ment (vida supra, F). Asa corollary to this it would appear
advisable to keep all material to be used for WEIGERT prepara-
tions, however fixed and hardened, in formalin instead of alco-
hol. Material kept long in alcohol will not usually yield brilliant
WEIGERT preparations.
It may be well to call attention here to the fact that sec-
tions already stained for WEIGERT but not decolorized may often
be kept for months in water containing some formalin (to pre-
vent the growth of molds etc.) and yet give good preparations
when decolorized. This proved to be the case with some sec-
tions prepared as indicated above under F (2). There is appar-
ently a very slight gradual loss in brilliancy. Sections stained
asin F (2) and kept thus 1%-yrs. in 10% + formalin still
yielded good preparations when decolorized. Some of these
which had been brought, after rinsing in water, into formalin
and the formalin changed when discolored were practically in-
distinguishable, when decolorized, from those decolorized im-
mediately after staining.
(c) Material fixed and hardened in formalin should in all
cases be mordanted: zz Zofo before bringing it into alcohol pre-
paratory to imbedding. Here lies the explanation, probably,
of the discrepancy between the results obtained with formalin
material by Borron' and those obtained by HErrIck.? BoLTon
mordanted sections made from frozen or gum imbedded material,
while HErrRIcK mordanted paraffine sections. It is also better
to mordant pieces of the material immediately before they
are to be used so that mordanted blocks need not be kept long
before cutting and staining.
It is probable, from this, that some of the apparently bad
fixation of ‘medullated nerve fibers seen at times in formalin
material is really due more to the subsequent treatment, the
1 Journ, Anat. Physiol. Vol. XII, N. S., 1898. 2 Op. cit.
STRONG, Technique of Weigert’'s Method. 299
formalin fixed fibers not being so resistant as fibers impregnated
with a metallic salt in the act of fixation and hardening. This
view would seem to be further confirmed by the observations
above noted (F (4)) where the fibers appeared to be in better
histological condition when the formalin material was first
treated with potassium bichromate + osmic than when treated
in other ways. The superiority of osmic acid in faithfully fix-
ing medullated nerve-fibers is well known.
(2) Preparations from pieces mordanted zx foto can often
be made more brilliant by remordanting the sections before
staining. When the points noted in (c) have been observed,
however, this may often be omitted, the gain being insignifi-
cant and the sections being liable to become brittle.
(e) The best mordant for WEIGERT-PAL preparations of
both formalin hardened and other material is probably bichro-
mate of copper, this apparently excelling WeEIGERT’s chrome
alum-bichromate mixture.
Bichromate of copper is a reagent which has some qualities
to recommend it in neurological work, It was first used by the
- writer in 1898 and had not been previously applied in histolog-
ical work as faras I am aware. It is an energetic fixing and
hardening reagent, more so apparently than any other bichro-
mate. This indicates its use, either with or without formalin,
in fixing and hardening foetal brains and spinal cords and as a
mordant which gives the most brilliant results when the WEI-
GERT-PaL method is to be used. Asa hardening fluid, the re-
sults here are confined practically to the above-mentioned (C)
cord of a 7 months foetus. The material and fibers were per-
haps somewhat overhardened and shrunken but yielded very
fine preparations. One hasty trial of this reagent in the method
of Gore did not produce noteworthy results.
(f/) Copper bichromate and other bichromates do not give
good results as mordants (unless, as in the usual method, there
is remordanting with copper acetate) where the borax-ferricy-
anide decolorizer is to be used.
(g) Copper acetate asa mordant invariably yields poor
300 JOURNAL OF COMPARATIVE NEUROLOGY.
results with the Pat decolorization unless osmic acid is used as
indicated below (£).
(2) Iron alum did not prove to bea valuable mordant—
except where used asa hardening reagent for the peripheral
nerves as above described. It was still worse as a decolorizer.
(¢) Mordanting the celloidin block zx ¢ofo without further
mordanting does not give such brilliant preparations as when
the celloidin sections are mordanted instead.
(7) No constant differences were noted between the WEI-
GERT alkaline haematoxylin and the neutral haematoxylin. Cer-
tainly with the Pat decolorization the neutral is as good or possi-
bly somewhat better.
(£) A slight or considerable increase in the brilliancy of
WEIGERT-PAL preparations can often be obtained by dipping
the sections in osmicacid for a fraction of a minute immediately
after they have been removed from haematoxylin and rinsed in
water. When this is done, sections mordanted in copper acetate
before staining will often give good results with the Pat decolor-
ization, though otherwise, as indicated above (g), they would be
useless for this method.
Osmic, used in this way before the borax-ferricyanide decol-
orization always gave poor results.
(7) The time of mordanting and staining is omitted in A,
B and C for purposes of condensation. When the time devoted
to these processes has been too short, the stain is too pale and
the finer fibers are not be well demonstrated; when too long, de-
colorization is too protracted and the ground will not be suffi-
ciently decolorized or the fibers will be over-decolorized. Nat-
urally, the longer the mordantage the shorter the time required
for staining. Usually, at the temperature of the room, about
12 hrs. for mordanting and about 4 to 6 hrs. for staining were the
most favorable, but no rule can be laid down, owing to the
condition of the material and other factors. Heat will of course
accelerate the process but this is not necessarily to be recom-
mended, it being liable, especially when mordanting with copper
bichromate, to render the sections brittle.
Dept. of Zoology, .
Nov., 1903.
DHE SDOCTRINE OF NERVE COMPONENTS AND
SOME, OF ITS: APPLICATIONS:*
By C. Jupson HERRICK.
The original purpose of the students of nerve components
was the analysis of the peripheral nervous system into units
which should have at the same time a functional and a struc-
tural significance. This obviously is not the case with the
cranial and spinal nervesas commonly enumerated. The struc-
tural peculiarities of each of the twelve pairs of cranial nerves,
for instance, while fairly well defined in the human body, are
very diverse in the vertebrate series as a whole. Thus the facial
nerve from being predominantly sensory in lower vertebrates
(more than half of its fibers in fishes belonging to a sensory
system not represented at all in mammals) becomes in man pre-
dominantly motor with only a vestigeal remnant of the sensory
components, and even the motor component innervates chiefly
muscles new to the. mammalia. We might multiply illustrations
of the structural instability of the cranial nerves. And that
the cranial nerves have any special significance as functional
units cannot be maintained for a moment, no two pairs in the
human body having even approximately the same function.
But the first measurably complete analysis of the cranial
nerves into their components for their entire extent showed at
once the presence of certain structural and functional systems
of components, the laws of whose distribution have apparently
little to do with the serial order of the cranial nerves as com-
monly enumerated.
We have, then, a number of systems of components each
of which is defined structurally by similarity of peripheral and
1 Presidential Address delivered before the Ohio State Academy of Science,
Nov. 27, 1903.
302 JOURNAL OF COMPARATIVE NEUROLOGY.
central terminal relations, and functionally by the trasmission of
nervous impulses of the same type or modality. Among these
systems are tactile, auditory, visual, olfactory, motor, gusta-
tory, etc., each with very characteristic terminal relations.
Now, this structure is absolutely meaningless apart from
its function. Let any one who doubts this spend a few months.
(as I have done) in trying to master and correlate the existing
literature of the cranial nerves of vertebrates. Though these
descriptions were for the most part written by famous masters
of anatomical science, yet in their aggregate they present an
indigestible mass of confused and meaningless detail, crude fact,
well spiced with error, for the most part not worth the prodig-
eous labor of digging it out of the oblivion of classic tomes of
by-gone anatomists.
I do not mean to imply that all the problems of cranial
nerve morphology are now cleared up; but I do claim that
there is no longer any necessity for the further accumulation of
uncritical and meaningless fact in this field of research. We
have already gone far enough to point the way toward certain)
lines of fruitful correlation. We can not only correlate structure
with structure, but we can interpret structure by function and.
thus bring out a fuller meaning. We are at least coming into a
realization of the fact that we cannot fully understand any struc-
ture until we know what it can do.
This point of view of course is not new, but as worked out
practically in the peripheral nervous system it is exerting a
clarifying influence upon our knowledge of the central system
also. The present demand in cerebral anatomy is for conduc-
tion paths, for functional systems of neurones, and precise
knowledge of the pathways between the brain and the periphery
is the first step in such a central analysis.
The primary function of the nervous system is to facilitate
the reaction of the organism to the external forces of the environ-
ment. Later, as the reacting mechanism becomes more com-
plicated, the nervous system assumes the function of coordi-
nating this mechanism, i. e., of reaction to the forces of the
internal environment. These two functions lie at the basis of
HERRICK, (Verve Components. 303
our most fundamental division in the analysis of the nervous
system ; viz.: (1) the somatic systems (sensory and motor) for
bodily responses to external stimuli, and (2) the visceral systems
(sensory and motor) for visceral reactions to internal stimuli.
Each of these great divisions has been analyzed periph.
erally, more or less imperfectly as yet, into systems of compo-
nents, as suggested above. Every such system of nerve fibers
performs a separate function, conducts a single type of nervous
impulse, either afferent, i. e., sensory, or efferent, i. e., excito-
motor, excito-glandular, etc. The following systems are already
distinguishable anatomically :
I. Somatic SYSTEMS.
1. Tactile, or general cutaneous,
2. Acustico-lateral, including nerves for lateral line organs (in the Ich-
thyopsida) and for organs of equilibration and hearing (in verte-
brates generally). These organs and their nerves have probably
been derived phylogenetically from the general cutaneous system
and, like the organs of the latter type, are adapted for the recep-
tion of various kinds of mechanical impact, either rhythmic or
non-rhythmic.
3. Visual (a system of uncertain relationships, provisionally classified
under the somatic sensory).
4. Somatic motor, for the innervation of skeletal or voluntary muscles.
II. VIscERAL SYSTEMS.
5: Vusceral sensory, unspecialized sensory nerves of the viscera, distrib-
uted chiefly through the sympathetic nerves.
6. Gustatory, innervating specialized sense organs (taste buds) of chem-
ical sense probably derived phylogenetically from the preceding
type.
7. Olfactory (provisionally classified here because of the apparent resem-
blance between taste and smell).
8. Visceral motor, distributed chiefly to unstriped and involuntary mus-
cles, generally through the sympathetic system.
9. ELxcito-glandular, provisionally classified here because of genera —
resemblance to the last mentioned type.
There are numerous other systems which can be differen-
tiated physiologically, but which cannot as yet be completely
separated anatomically and classified, such as nerves for the
304 JoURNAL OF COMPARATIVE NEUROLOGY.
thermal sensations, muscle sensations, etc., but enough has
been cone to enable us to lay down the general plan or pattern
of the periphera) nervous system asa whole and to define
the main pathways by which stimuli of different modalities
reach the brain and are reflected back to the responsive organs.
Our anatomical knowledge of these pathways is sufficiently well
controlled by precise physiological experimentation to enable us
to state with confidence that each of the nine systems mentioned
above is a real functional unit.
The fibers composing these systems may reach the central
nervous system through a series of many nerve roots arranged
in a segmental way, like the general cutaneous nerves of the
spinal cord, or they may all be represented in a single large
nerve, like the optic and olfactory. Thus it happens that some
nerves, like those last mentioned, are ‘‘pure’’ nerves, while
others, like the facialis or vagus, are ‘‘mixed,’’ containing in
some cases as many as four anatomically distinguishable com-
ponents.
It is a general rule that in the body the components tend
to be distributed among a large number of nerves in a more or
less segmental way, while in the head they tend to be concen-
trated into a few pathways, or only one, into the brain, an adap-
tation which presents obvious advantages for the simplification
and unification of the secondary reflex paths from these pri-
mary centers.
Now, the central nervous system is, as we have already
seen, primarily a mechanism to facilitate the reaction of the
animal to impressions from without, in other words, to put the
body in correspondence with the environment. Its structure is
directly determined by the avenues of sense through which
these stimuli come in and by the character of the responses to
these stimuli which are necessary for the conservation of the
organism. In view of the fact that we already possess a de-
tailed knowledge of these peripheral nervous pathways, it is
manifest that we have here a most favorable avenue of approach
in an analysis of the inconceivable complexity of cerebral
structure.
HERRICK, Verve Components. 305
We must know in detail the possible reflex pathways in
the brain for all olfactory, visual, gustatory responses, etc., in
the vertebrate type, and then on the basis of such a functional
subdivision of the brain the problem of the mechanisms of
higher cerebral processes may be attacked with a reasonable
hope of success. The investigation of the internal organiza-
tion of the brain may be pursued in several ways:
I. The direct study of the human brain, both normal and
pathological. On account of the enormous practical importance
of neurology to both human psychology and pathology, re-
search naturally turned directly to the human brain; but a more
unfavorable starting point could not be found.
II. It is now generally recognized that the complex hu-
man brain can best be understood by finding first a simpler pat-
tern such as is presented by one of the lowest vertebrates. Ac-
cordingly the phyletic method has dominated all recent neuro-
logical research. The brains of individual species are studied
and monographed, particular attention being paid to the lower
members of the vertebrate series in the hope of finding in them
a schema or paradigm which can be followed upward through
the comparative anatomical series and, after comparison with
the ontogeny of higher brains, lead to a reconstruction of the
phylogenetic history of the brain. While this method has been
of great service, especially to such problems as can be ap-
proached from the study of external morphology, it is im-
mensely difficult when applied to the histological problems, and
as a matter of fact has not as yet taken us very far.
III. A third method, instead of taking an entire brain as
the unit of research, concentrates attention upon a single func-
tional system and seeks to get exhaustive comparative knowl-
edge of it in many types. Starting with a fairly accurate and
detailed knowledge of the functional systems at the periphery,
we have simply to extend the lines of inquiry here blocked out
for us.
This gives a type of problem which is much more ap-
proachable than the others. It is iiot so complex but more
306 JouRNAL OF COMPARATIVE NEUROLOGY.
intensive. Of still more importance are the facts that the ana-
tomical data can be directly correlated by physiological experi-
mentation, and the method is open to experimental control all
along the line. Our degeneration methods open up _possibili-
ties here which are incomparably more valuable than the most
precise anatomical observation.
And nature has performed for us a series of experiments
which are in a sense the converse of our degeneration methods.
The various sensori-motor systems are very unequally developed,
some animals possessing one ina high state of elaboration,
some another. If therefore we begin our studies on the visual
system for instance, with animals such as most birds with very
highly developed eyes, and then compare with animals with
vestigeal eyes, it is evident that we have here a means of isolat-
ing the system for scientific study which has some points of
superiority over artificial experimental methods. Fortunately
within the group of fishes, whose brains are all constructed on
a plan fundamentally similar, we have the most remarkable di-
versity in the degree of development of the several systems, so
that this is a favorable starting point for this method, especially
since the brain is composed almost wholly of the simpler reflex
mechanisms without the complications which we find in mam-
mals due to the enormous development of higher associational
centers in the forebrain. Some fishes have huge eyes, some
are blind; some have elaborate olfactory apparatus, some very
slight ; some show a marvelous hypertrophy of the organs of
taste, or touch, etc. These organs are all open to physiologi-
cal study and so the functions can be accurately determined.
Then, having found the cerebral pathways for each system
where it reaches its maximum development, we can more easily
trace out the system in other types, and thus arrive ultimately
at a full knowledge of its evolutionary history.
All scientific method is both analytic and synthetic. In
the phyletic type of neurological method, these two processes
are apt to be far separated and the observed facts may remain
inert and relatively meaningless, because imperfectly under-
stood, incoordinated. In our third type of method, on the other
Herrick, Verve Components. 307
hand, it is easier to correlate the data as we go along, the syn-
thesis accompanies the analysis, and the possibility of experi-
mental control should keep the student in closer touch with his
guiding facts and discourage general speculation.
As a concrete illustration of the practical method of apply-
ing the doctrine of nerve components in the functional analysis
of the nervous system, we may summarize briefly the progress
which has been made up to date in the study of the gustatory
system.
In man, as is well known, the sense of taste is not very
highly developed. The peripheral organs, or taste buds, are
situated chiefly on the tongue, those near its base innervated
by the glossopharyngeal nerve, and those near the tip probably
by the chorda tympani of the facial nerve. But the gustatory
pathway toward the brain is very imperfectly understood and
many points are still in controversy, while the central path is
almost wholly unknown.
; But in certain fishes, such as the carp and cat fish, this
system of sense organs is enormously exaggerated. Taste buds
are found, not only in the mouth, but all over the outer skin
- and barblets. Direct experiment shows that these fishes actually
do taste with these superficial sense organs—unlike some peo-
ple, their taste is not all in their mouth.
The experiments made on the cat fish (Ameiurus) show
that these fishes seek their food by feeling for it with the barb-
lets and by means of them they discriminate between edible
and non-edible substances, that they habitually use both the
sense of touch and the sense of taste for the purpose and that
they can be taught to discriminate between tactile and gusta-
tory stimuli applied to the skin and will turn and snap up sav-
ory substances and reject objects which feel like them but are
devoid of taste.
The exact distribution of the gustatory sense organs has
been determined and their nerves traced back to the brain. We
get the gustatory reaction from the skin as described above in
fishes which possess these cutaneous sense organs, and the reac-
308 JOURNAL OF COMPARATIVE NEUROLOGY.
tion is not obtained from fishes which do not possess such sense
organs and nerves. |
All of these cutaneous sense organs are innervated from a
single nerve, the sensory root of the facial (corresponding to
the portio intermedia of human anatomy), which is the biggest
nerve in the body. The center in which this nerve terminates
in the medulla oblongata is about as big as the entire forebrain,
instead of being barely discernable by refined histological meth-
ods, as in the human body. And the secondary gustatory
path, which in man is totally unknown, is the largest single
tract in the brain, both in the cat fish and in the carp!
The primary gustatory center in the medulla oblongata is
bilobed, the ‘‘ facial lobe”’ receiving the gustatory fibers from
the skin and the ‘‘ vagal lobe
From these lobes there is both an ascending and a descending
”
receiving those from the mouth.
gustatory path. The latter passes down to the point where the
medulla oblongata merges into the spinal cord and there termi-
nates in a special nucleus which is intimately related to the
funicular nuclei, a center for tactile sensations. Here the tac-
tile and gustatory stimuli are coordinated and a comimon de-
scending bundle (tertiary path) passes back into the spinal cord
for the body movements necessary to turn toward the food ob-
ject. The ascending secondary gustatory path extends upward
to a big nucleus under the cerebellum, from which tertiary path-
ways extend forward and downward into the midbrain (chiefly
in the inferior lobe), then backward by a descending path of
the fourth order into the medulla oblongata to reach the motor
nuclei of the cranial nerves.
We have already gone far enough into our analysis of
these secondary and tertiary gustatory paths to make it per-
fectly safe to predict that all of the habitual gustatory reflexes
which we have observed in these fishes can be followed anatom-
ically through the brain for their entire extent. | And since we
have the strongest reasons for believing that the elementary
reflex paths are essentially similar in mammals and fishes, we
expect to find here an important guide for further research in
human anatomy.
Herrick, Nerve Components. 309
So the other sensori-motor systems may be severally inves-
tigated, beginning the attack in each case with some species
low down in the, vertebrate series in which this particular
mechanism is highly developed, and then extending the re-
search to higher and lower types.
We may ultimately hope for a subdivision of the brain
which shall be both structural and functional, each organ or
pathway being given its function or meaning in the system as a
part of the machinery of keeping the body in vital, helpful
contact with environing forces. The great morphological
‘thead problems,’ such as the primitive metamerism and the
subsequent marvelous kalaidoscopic changes in structure and
function of the component segments, these must all be read
through the medium of such an intensive study of these factors
upon which all differentiation has in last analysis depended.
There is another point of view from which I have been
somewhat interested to develop the implications of the doctrine
of nerve components, that of scientific methology in general.
It is said that scientific explanation consists essentially in
such an organization of facts that they may be generalized or
included under certain laws or uniformities which permit a fore-
casting of future events. Now, without going into an exposi-
tion at this time of the implied philosophy of nature, I think
that a little reflection will show that this statement, while true
in a certain limited sense, is very defective.
What is the nature of this organization of facts from which
so great benefits are expected to flow? Can it in last analysis
be anything other than the correlation of experience? All of
the ‘‘facts’” with which we deal have grown up in experience;
they are in a literal sense the products of our experience. As
men of science we have nothing to do with ‘‘things-in-them-
’ only with phenomena, out of which we have con-
structed by mental process certain objective things which we
regard as real—‘‘constructs,’’ or in common parlance, objects,
facts, data.
selves,’
By these things which grew up in experience (we have in
most cases forgotten how) we measure up and evaluate all new
310 JouRNAL OF COMPARATIVE NEUROLOGY.
experience. If the new sense presentation is a yellow dog with
white feet we assimilate it at once with previous experience and
approve it as a valid fact. If, on the other hand, it is a green
dog with thirteen scarlet heads each with a forked tongue, we
are apt to ask, Am I awake or asleep? or, What was I drink-
ing last night? Such an experience may be vividly real to me,
but if awake and sane I do not accredit it as an object of sense,
as a fact of experience, unless I can correlate it with the body
of fact already approved.
But scientific laws are merely ‘‘facts’’ of wider import,
which rest on a foundation of broader experience such that,
when objectified, they remain not as concrete elementary exper-
iences but as general categories including many such elements.
The scientific generalization or law must therefore be approved
or evaluated in a way strictly analogous with that by which we
test sense impressions; that is, to be acceptable it must fit in
harmoniously with the whole content of experience—‘‘it must
explain all the facts.”’
In the solution of any scientific problem that method is
most likely to lead directly to fruitful results, other things being
equal, which favors the correlation of the data all along the line
so that each correlation may become at once a datum for future
research, instead of reserving the major correlations until near
the end of the investigation. And in biological research, to
return to our text, we must not forget for an instant that the
organism is a functoonmmg mechanism. We cannot hope to un-
derstand any animal or plant or organ until we have an exhaus-
tive knowledge of how it works. The anatomical fact is dead
and inert unless it is vivified not only by the ‘‘salt of morpho-
logical ideas’? as it was so happily phrased years ago, but also
by the fresh warm blood of functional explanations.
Anatomy has given place, within the memory of even the
younger generation of biologists, to morphology, in which the
explanation is indissolubly linked with the fact. Nor can we
stop here. No anatomical fact is complete until its physiolog-
ical significance is added thereto. Like the old-time descriptive
anatomist, the ‘‘pure’’ morphologist (or shall we dubb him
Herrick, Nerve Components. 311
‘‘poor morphologist’’?) has no longer any tenable standing
ground. What I mean is that anatomical structure cannot be
understood as the morphology of today demands that it must
be understood without a full knowledge of the functions of the
parts, and we must ‘know evolution of function before we can
have true knowledge of the evolution of structure. Andasa
matter of fact the biological public is just now coming into a
practical realization of the truth that we must have a compara-
tive physiology parallel with our comparative anatomy. It
seems to us now very strange that we have had to wait a whole
century after the birth of comparative anatomy for even the
beginnings of a realization in practice of this elementary
principle.
That researches in descriptive anatomy and in pure mor-
phology are still necessary and will continue to be called for to
the end of the age there can be no doubt; but it is important
that we remember that no study of structure is complete until
the whole significance of that structure (including the evolution-
ary history of both its form and its function) is exposed and
the whole complex of fact and meaning not only woven to-
gether into a single fabric, but fitted into the great pattern of
reality as a whole in its proper place.
Now, no one of us can do this perfectly and, as time ad-
vances and the totality of the known becomes ever more vast
and intricate, the difficulty grows apace. And yet this we must
do in some measure in so far as we hope to rank as real build-
ers inthe permanent temple of truth. If we find ourselves
unable to see the whole edifice in its proper perspective (as in-
deed who can ?) we can at least build harmoniously with that
nitch in which we find ourselves. Let no man delude himself
with the idea that he is building for himself alone, that he builds
on no other’s foundation or that he can with safety ignore the
labors of his coadjutors. Let no research worker hedge him-
self about and work in isolation ; harmonious cooperation is the
only possible way to get that breadth of view which all lack as
individuals.
a2 JOURNAL OF COMPARATIVE NEUROLOGY.
In our work on the nerve components we have endeavored
to live up to these ideals. In so far only as we succeed in ef-
fecting wide and stable correlations from both the anatomical
and the physiological side can we hope to be able to build a
structure which shall endure as a secure foundation for an ulti-
mately complete functional subdivision of the nervous system.
COLUMELLA AURIS AND NERVUS FACIALIS: IN
THE URODELA.’
By B. F. Krinespury.
The following communication sets forth the results of a
study made upon the relations and development of the parts in
the otic region of the head in Necturus maculatus, and
in comparison with that form, Desmognathus fusca and Spel-
erpes bilineatus.
The need fora careful study of (1) the relations of the
facial nerve to the columella auris in the various Urodela, and
(2) the homology of the suspensorio-opercular connections in
the different forms of Amphibia has been emphasized by
Gaupp.” From a comparison of the statements of WIEDER-
SHEIM,® Hux ey,‘ ParKeEr,°® and Hasse® he was lead to conclude
1 This may be considered as a partial preliminary communication upon the
development of the skull of Necturus maculatus, undertaken at the suggestion
of Professors WIEDERSHEIM and GAUPP, in the Anatomisches Institut at Frei-
burg. I wish to acknowledge my indebtedness to them and to Professor KEIBEL
and others, for suggestions and material. Since the completion of this manu-
script in May 1902, more than a year has elapsed, and in sending it to the press
now, I take the opportunity of noticing papers that have appeared in the mean-
time—those of KINGSLEY and COGHILL.
298, Gaupp, E Ontogenese und Phylogenese des Schalleitenden Appa-
parates bei den Wirbeltieren. Merkel u. Bonnet, Ergebnisse d. Anat. u. Entw.,
1898, Bd. VIII, pp. 989-1149.
3°77, WIEDERSHEIM, R. Das Kopfskelet der Urodelen. Morph. Jahré.,
Bd. I1I, pp. 352-548.
#74, HUXLEY, TH. H. Onthe Structure of the Skull and the Heart of
Menobranchus lateralis. Proc. Zool. Soc., 1874.
5?77, PARKER, W. K. On the Structure and Development of the Skull in
the Urodelous Amphibia. Pt. I. Phzlos. Trans. Roy. Soc., Vol. 167, Pt. 2.
82a, On the Morphology of the Skull in the Amphibia Urodela. 7Z7yvans.
Linn. Soc., Ser. 2, Vol. I1.
82b, On the Structure and Development of the Skull in the Urodeles.
Trans. Zool. Soc., London, Vol. XI, pp. 171-214.
6°73, Hasse, C. Ueber den Bau des GehGérorgans von Siredon pisciformis
und iiber die vergleichende Anatomie des Kiefersuspensorium. Anat. Stud.,
Bd. I, No. XV.
314 JOURNAL OF COMPARATIVE NEUROLOGY.
that there were apparently two methods of connection of the
operculum with the suspensorium (quadratum). Thus, WIEpD-
ERSHEIM gives as the universal condition, that the nervus facialis
passes above the suspensorio-opercular connection ; Hux try de-
scribed a suspensorio-stapedial (opercular) ligament wxder the
facial nerve; Hassr, in Siredon (Amblystoma) described the
nerve as under the columella; while the statements of PARKER
are not always clear, though it is evident that in the different
Urodela both relations of columella or suspensorio-opercular
ligament and nerve were described.
The study of the relations in the three forms above men-
tioned, to which Proteus anguineus, Amphiuma means, and
Amblystoma tigrinum (larva) may. be added, has shown that in
all except Necturus, the nervus facialis passes below (ventrad
to or cephalad of ) the suspensorio-opercular connection. In
Necturus, the ramus jugularis facialis passes above (dorsad to)
the ligament, the remainder of the nerve, i. e. ramus mandibu-
laris externus and internus, and ramus palatinus being below
(ventrad or cephalad to) this structure. Furthermore, in these
three forms, the columella or ligament passes from the opercu-
lum to the bone which lies partly upon the ear capsule and
partly upon the external surface of the quadratum—and which,
as far as I can judge from the evidence at hand, I regard asa
squamosum ;—and not (primarily) to the cartilage of the quad-
ratum as heretofore stated. This isa fact of considerable mor-
phological importance. A more detailed description of the
relations in the forms follows :
Necturus Maculatus.. In this form Hux.ey' described the
‘‘suspensorio-stapedial ligament’ as arising from the ‘‘middle
of the posterior edge of the quadratum—and passing upwards
and backwards to the stapes. The Hyomandibular branch of
the seventh nerve passes passes above this ligament to its dis-
tribution just as it passes above the columella auris in the Frog.”’
WIEDERSHEIM made no different statement of relations. This
structure described by Hux.ey, which was presumably a sheet of
VOps ctit-p. 192.
Kinespury, Columella Auris and N. Facials. 2a
fascia, is not the true suspensorio-opercular connection, which is
correctly described by Cope,’ as passing from the operculum to.
fig. 7. Diagram from a drawing of the left side of a model of the skull of a
Necturus 49.5 mm. long.
a.—Os articulare (angulare ?). 6.—Nervus bucecalis.
c.—Columella (operculum). d.— Os dentare.
f.—Os frontale. A.—Ceratohyale.
7-—Ramus jugularis VII.
L. A.-s.—Ligamentum hyo-suspensoriale.
L. m.-h.—Ligamentum mandibulo-hyoidale.
L. s.-e.—Ligamentum squamoso-columellare.
m.e. VZ/,—Ramus mandibularis externus facialis.
m. V.—Nervus maxillo-mandibularis trigemini.
m. z2.—Ramus mandibularis internus facialis.
o.—Nervus opticus. o. m.—Nervus oculomotorius.
o. p.—Ramus ophthalmicus profundus trigemini.
o. g-—Os quadratum.
o. s.—R. ophthalmicus superficialis facialis. p.—Os parietale.
pp.—Os palatopterygoideum. ps.—Os parasphenoideum.
g.—Quadratum. r. c.—Ramus communicans glossopharyngei.
s.—Os squamosum. t,—Trabeculum.
the squamosum, who does not however, give the relation of the
nervus facialis. DDrtNER has recently described correctly the
relations in both Necturus and Proteus.
1Copr, E. D. The Batrachia of North America. Bull. U. S. Nat’l. Mu-
seum, No. 34, 18.
316 JOURNAL OF COMPARATIVE NEUROLOGY.
The following description of the relations in a Necturus of
49.5 mm. length, based in part on a model of this stage (Fig. 1),
will serve asa basis of comparison. The operculum at this
stage is roughly oval in outline and slighly ridged along its long
axis. At its cephalic end it is fused with the otic capsule, pro-
jecting backward into the fenestra vestibuli. From the cephalic
end a dense ligament passes cephalad and dorsad to the os
squamosum at about its middle point. The bone forms a slight
curve, the convexity looking upwards, and it lies upon the
external semicircular canal of the otic capsule, extending down
over the otic process of the quadrate and becoming closely
connected with a bone lying upon the external surface of the
quadratum, and which it partly covers. This bone’ I shall
describe in another place. The squamoso-opercular ligament
is attached to the under side of the squamosum where the bone
passes from the ear capsule to cover the outer side of the pro-
cessus oticus quadrati. At this stage the ‘‘stapedial’’ process
of the squamosum present in the adult has just begun to de-
velop. The ligament, in its course from the operculum to the
squamosum, passes external (laterad) to the ramus jugularis
facialis and the vena jugularis. The ramus jugularis passes out-
ward and slightly backward, between the ligament and the vein
to the dorsal edge of the former where it receives the ramus
communicans glossopharyngei, which lies close to the ear cap-
sule laterad to the vena jugularis. Beyond the point of the
union with the ramus communicans, the jugular branch of the
seventh passes outward, under the ventral edge of the squamo-
sum to curve around the dorsal side of the otic division of the
M. depressor mandibuli. The ramus mandibularis externus
facialis from its ganglion which lies immediately outside the
foramen for the facial nerve, in a depression just caudad of the
1 This bone arises in Necturus as a separate ossification, whose lower end
subsequeutly is fused with or becomes the ossification of the quadrate. In
Desmognathus and Spelerpes the same bone lies farther back, projecting under
the squamosum, and in the adult forms the process of the quadrate named for
the purposes of this paper the subsquamosa! process.
Kinesspury, Columella Auris and N. Factalts. Br7
processus basilaris quadrati, "passes forward and outward under
the quadratum to the outer surface of the squamosum, passing
in front of (ventrad and cephalad to) the ligament.
The ramus palatinus which passes forward through a fora-
men distinct from that for the rest of the facial nerve, and the
ramus mandibularis internus which passes immediately ventrad
from the cephalic edge of the accessory lateral line ganglion,
do not come into close relation to the columella, but are, of
course, morphologically below and in front of it.
In an older Necturus, 9.4 c.m. long, the relations are as in
the specimen just described, save that the processus ‘‘staped-
ialis’”’ of the squamosum has attained an appreciable length, and
the operculum possesses a short ossified stalk to which the liga-
Fig. 2a. Section of the Necturus embryo 19 mm. in length. c.—anlage of the
squamoso-columellar ligament; 4.—hyoid: v. 7.—vena jugularis ; 2. 7.—
nervus jugularis ; @. #.—M. depressor mandibuli; s.—squamosum.
Fig. 26. Same, three sections farther forward.
ment attaches. Neither ossification appears to be an ossifica-
tion of the ligament, but ossifications of the squamosum and
operculum at each end of the ligament, acomplishing in that
way the increase in length due to growth. In the adult, the
operculum possesses an ossified process of some length joined
318 JOURNAL OF COMPARATIVE NEUROLOGY.
by ligament to the relatively long stapedial process of the
squamosum.
That the relation of ligament to squamosum is a primary
condition in this form and not a secondary modification, is seen
in tracing the development of these structures. In an embryo
Ig mm. in length (Fig. 2), the ossification of the squamosum is
just beginning as a formation ina group of cells located upon
the external semicircular canal of the ear. It extends down
over the otic process of the quadratum covering with its lower
(cephalic) end the upper end of a bone which is developed upon
the external surface of the quadrate. At this stage, the oper-
culum is just beginning to chondrify as a distinct center, and
from it a cord of cells is continued forward, ventral to the vena
jugularis and the ramus jugularis, to the cell surrounding the
developing squamosum, becoming continuous with them a short
distance (50y) back of the processus oticus quadrati. The cells
are of course continuous with those of the squamosum and also
with the cells between that bone and the quadratum, so that the
squamosum, the quadratum, and the ligament-anlage, may be
said to be joined together by a common mass of cells. In the
just hatched larva, likewise, the ligament-anlage, clearly goes
to the under side of the squamosum and inserts itself between
that bone and the processus oticus quadrati, so that it might be
interpreted as going to both structures. As soon as the con-
nective tissue fibers develop, however, the relation is seen to be
with the squamosum and not with the quadratum. It is inter-
esting to note the relatively early development of the ligament
—practically at the same time as the squamosum and the oper-
culum—later, however, than the chondrification of the chon-
drocranium.
Spelerpes bilineatus. In this form, as well as in Desmog-
nathus, the suspensorio-opercular connection possesses the same
relation to the nervus facialis—that is, the nerve lies entirely
cephalad and ventrad to the stilus columellae; in other words,
under it. In relation to the jugular vein, the stilus possesses
the same relation as the ligament described in Necturus—i. e.
it passes ventrad to it.
ee
Kincssury, Columella Auris and N. Facials. 319
In the adult Spelerpes (Figure 3), the stilus is cartilagin-
ous with a perichondral ossification continuous with the ossifi-
cation of the operculum;—the cartilaginous core of the stilus,
however, is distinct from the ring of cartilage within the
operculum.
i ——_——-—
_>—
Fig. 3. Spelerpes bilineatus, adult 67 mm. long. Section through the right
otic capsule. c—Stilus columellae; o0—oral cavity; v. 7.—vena jugu-
laris; @. m.—M. depressor mandibuli; S.—squamosum.
The stilus passes forward, upward and slightly outward to
the lower edge of the squamosum with which its cephalic end
is joined by connective tissue (Fig. 3), and also with a small
cartilage which lies upon the ventral edge of the squamosum.
This cartilage extends forward for about 150 microns and is
cylindrical. It is free at its caudal end, which articulates with
the stilus, and fused with the ventral edge of the squamosum.
The stilus and operculum are at about the same level. The
former lies at first upon the dorsal side of the external semi-
circular canal, gradually moving down to the lateral surface of
the otic capsule, as it is traced forward. As it continues to
320 JOURNAL OF COMPARATIVE NEUROLOGY.
shift its position ventrally to pass to the outer surface of the
quadratum, it becomes farther separated from the ear capsule
leaving a space in which the quadratum appears. The ventral
(lateral) edge of the squamosum is thin where the bone rests
upon the ear capsule, but becomes thicker as the bone leaves
that structure, i. e. where the stilus articulates with it, becom-
ing thinner again as the bone applies itself to the quadratum.
Fig. 4. Larval Spelerpes bilineatus, 43 mm. long; c.—stilus columellae ;
v, j-—vena jugularis; #. 7.—nervus jugularis; d@. m.—M. depressor
mandibuli; s.-~Squamosum.
In the interval between the squamosum and the ear capsule,
two processes of the quadratum extend backward, (1) a bony
process applied immediately to the inner surface of the squa-
mosum, extending back to the level of the cephalic end of the
cartilage upon the ventral edge of the squamosum, and (2) a
short cartilaginous process lying between the bony process and
the ear capsule. The latter seems to be a part of the (morpho-
logically) basilar process of the quadratum and is very short.
Kincssury, Columella Aurts and N. Facials. 321
Neither one comes into relation to the columella as do the cor-
responding processes in Desmognathus.
Larval Spelerpes of 25 mm., 35 mm., 43 mm. (Fig. 4)
and 60 mm. in length, were examined in this connection and
showed that the relation between columella and squamosum in
this form (Fig. 4) is a primary one, as in Necturus. In the 25
mm. larva, the suspensorio-opercular connection is represented
by a cord of cells which passes from the operculum forward
and upward to the ventral edge of the squamosum. This cell
cord lies ventrad to the vena jugularis around which it curves,
closely applied to the vein, compressed between it and the R.
jugularis facialis, the relation of nerve and suspensorio-oper-
cular connection being thus the opposite of that in Necturus.
Compare Figs. 2 and 4. In a 35 mm. larva cartilage has
appeared in the cord of cells, otherwise the relations are essen-
tially the same as in the younger larva, while in the 43 mm.
specimen ossification of the stilus has begun, continuous with
the perichondral ossification of the operculum.
The facial nerve, as has been said, lies entirely cephalad
and ventrad to the suspensorio-opercular connection. The
only branch which comes into contact with the stilus is the
ramus jugularis which in the larva passes close to the ventral
border of that structure. The ramus communicans glos-
sopharyngei likewise, passes below the stilus, curving around it
from its dorsal side in a course forward to join the facial. In
the adult neither nerve is in as close relation to the stilus as in
the larva.
The origin and significance of the small cartilage applied
to the ventral border of the squamosum is obscure because of
the absence of transforming and young adult material. In the
larva it is not present.
With the exception of the R. jugularis and R. communi-
cans, then, the suspensorio-opercular connection in Spelerpes
has the sime morphological relations as the ligament in
Necturus.
Desmognathus fusca. (76 mm.) In this form it would
seem as if, as compared with Spelerpes, the suspensorium were
322 JOURNAL OF COMPARATIVE NEUROLOGY.
displaced backward in relation to the operculum, so that the
stilus is shorter, passes more directly outward and upward, and
is joined more closely with the subsquamosal process of the
quadrate (Fig. 5) than with the squamosum itself. It is,
Fig. 5. Desmognathus fusca, adult, 76 mm. c—stilus columellae; ¢. /.—
canalis lateralis; 4.—hyoid; wv. j.—vena jugularis; 7. c.—ramus com-
municans; @. m.—depressor mandibuli; /. s,—subsquamosal process of
quadratum ; s.— squamosum.
however, joined to both bones by connective tissue, and with
the cartilaginous process of the quadrate. This process is
longer than the corresponding process in Spelerpes and is sepa-
rated from the stilus by an interval of but (ca.) 50 w (Fig. 6).
The squamosum and the subsquamosal process of the quadrate
are essentially the same as in Spelerpes. Stilus and operculum
are as in Spelerpes, though the cartilage in the columella is
small.
Kincssury, Columella Aurts and N. Factalis. 323
Turning to the larval form for an interpretation of the con-
dition in the adult, we find in a specimen 21 mm. in length,
that the suspensorio-opercular connection is at this stage cellu-
lar and extends from the cephalic border of the operculum to
the squamosum as a dense cord of cells. It has the same rela-
Fig. 6.4'Same,’three sections (75 yz) farther forward; g.—cartilaginous (colum-
ellar) process of the quadrate.
tion to the jugular nerve and vein as in Spelerpes, though it
does not come into as close contact with either as in that form.
Its cephalic end is rather difficult to determine (Fig. 7), since
the anlage is continued forward to join the subsquamosal pro-
cess (of the quadrate) which at this stage is a distinct bone, so
that it may be said to be connected with both bones. There
is, however, no direct connection with the (cartilaginous)
quadrate, and from} the conditions in Necturus and Spelerpes,
we are warranted, I think, in emphasizing the connection with
the squamosum rather than that with the subsquamosal process
of the quadrate which, in fact, is not as direct. Ina larva 33
324 JOURNAL OF COMPARATIVE NEUROLOGY.
mm. in length (Fig. 7), apparently approaching the period of
transformation, the relations are as in the younger specimen
save that cartilage has appeared in the suspensorio-opercular
connection as a center distinct from the cartilage of the operc-
Fig. 7a. Larval Desmognathus fusca, 33 mm. ; c.—stilus columellae; v. 7-—
vena jugularis; #. 7.—nervus jugularis (R. communicans) ; @. m.—M.
depressor mandibuli; #. s.—subsquamosal process of the quadrate ;
§.—Squamosum.
Fig. 76. Same; three sections farther forward.
ulum. In a small adult (27 mm.), presumably but recently
transformed, the cartilaginous stilus is connected more directly
with the squamosum, but also by dense connective tissue with
Kinessury, Columella Auris and N. Facialts. 325
the subsquamosal and the short cartilaginous processes of the
quadrate. The shifting of the attachment takes place in the
growth of the adult rather than at the transformation of the
larva.
Ampliuma means (51 mm). Through the courtesy of my
co-worker, Professor H. W. Norris, I am enabled to give here
the following brief statement of the relations occurring in
Amphiuma as found by him and verified by myself in his prep-
arations. This form is interesting because it possesses a con-
tinuous cartilaginous connection between the quadrate and oper-
culum, as described by WrepeERsHeEIM,' Hay,” and WINsLow.’*
This has been spoken of as the columella, and as the stapedial
process of the quadrate. It evidently, however, represents
both the columella (stilus columellae) and the primarily cartilag-
inous process of the quadrate found in Desmognathus. The
articulation in the specimen upon which this statement of rela-
tions is based is much closer than it is in Desmognathus, and in
older specimens undoubtedly, as described, there occurs a
fusion of the two structures to form one continuous rod _be-
tween the operculum and the quadratum. In this specimen,
the stilus is a cartilaginous process of the operculum which is
itself cartilaginous. The stilus columellae goes forward and
slightly upward to become applied to the thickened ventral
border of the squamosum to which it is joined by connective
tissue. It is succeeded by the cartilaginous columellar process
of the quadrate to which it is very closely connected. This
process lies also against the ventral edge of the squaamosum and
slightly on its inner side. The connection of the stilus, there-
fore, is with the squamosum and the cartilaginous process of
the quadrate and not at all with the ossification which (from the
condition in the adult Desmognathus and Spelerpes) I have
spoken of as the subsquamosal process of the os quadratum.
NOp-cit-,, p. 502.
2°90, Hay, O. P. The Skeletal Anatomy of Amphiuma during its earlier
Stages. Journ. Morph., Vol. IV.
5’98, WinsLow, G. M. The Chondrocranium in the Ichthyopsida. 7 fts
College Studies, No. 5, 1898.
326 JOURNAL OF COMPARATIVE NEUROLOGY.
All branches of the facial nerve pass below the stilus
columellae (and stapedial process of the quadrate) as has
already been stated by Hay, instead of over it.’
Other Urodela. In Menopoma (Cryptobranchus) alone is
the relation of columella to the squamosum described by
WIEDERSHEIM,” and also by PARKER.”
In Amblystoma I can only state that there is present in the
larva a cord of cells, passing from the operculum to the ventral
border of the squamosum, which from the position and rela-
tion (dorsal) to the facial nerve is undoubtedly the anlage of
the suspensorio-opercular connection. This relation of the
‘‘columella’’ to the facial nerve, has already been affirmed by
Hasse and PARKER.
Proteus anguineus. Opportunity for studying the relations
in this form was afforded me by the generosity of Professor
WievERSHEIM. As might be expected from the published fig-
ures (WIEDERSHEIM ; op. cit., Fig. 1g), the relations in Nec-
turus and Proteus are the same. There is a strong squamoso-
opercular ligament passing from the stapedial process of the
squamosum to the short stilus columellae, and to this the
branches of the facial nerve have the same relation as in Nec-
turus; R. jugularis passes above the ligament, R. mandibularis
externus below it.
Nervus factalis.*
Since the homology of the chorda tympani is closely con-
nected with that of the relations and connections of the colum-
ella auris, the following brief account of the course of the
branches of the facial nerve is offered. The relations of the
nerve in the larvae only of Desmognathus and Spelerpes have
1 This is also in accord with KINGSLEY’s description. (7«/t's College
Studies, No. 7, p. 3705.)
2\Op; Cit., p: 502.
Ops Gite bt. Lu spewed.
* The following names of the branches of the ‘facial nerve are used: R.
palatinus; R. jugularis (FISCHER); R. mandibularis internus (R. Alveolaris,
FISCHER); R. mandibularis externus (R. mentalis, FISCHER).
Kinesspury, Columella Auris and N. Factalis. 327
been studied, as the changes at transformation introduce com-
plexities unimportant in this connection.
Necturus (9.4 cm.). The ganglion geniculi is intra-cranial,
in the beginning of what might be described as a short facial
canal, adjoining and cephalad of the cephalic division of the
auditory nerve. From this ganglion the ramus palatinus arises
as a small nerve which passes cephalad and ventrad through a
separate foramen, and goes cephalad at the side of the trabe-
cula, finally passing ventrad between the parasphenoid and the
pterygo-palatinum to the roof of the oral cavity. The remain-
der of the nerve passes laterad through its foramen and develops
a second ganglion, which undoubtedly belongs to the R. man-
dibularis externus, a part of the lateral line component. At
this ganglion the nerve divides into two branches, R. mandibu-
laris facialis, and R. jugularis; the former divides, as soon as it
leaves the ganglion into the Rami mandibularis externus and
internus. The R. jugularis passes upon the caudal side of the
ganglion and has but little if any connection with it. Its course
is nearly directly laterad for a short distance, passing dorsad to
the ligament between that structure and the jugular vein ; be-
yond the ligament, under the ventral edge of the squamosum
it turns ventrad and caudad around the dorsal border of the otic
division of the M. depressor mandibuli to pass under the fascia
coveriny the lateral surface of that muscle. At the lateral border
of the M. mylohyoideus posterior, it passes to the ventral side of
that muscle. It innervates the M. depressor mandibuli, ceratohy-
oideus, and mylohyoideus posterior. The Ramus communicans
glossopharyngei passes forward from the ganglion complex of the
IX and X and joins the R. jugularis just beyond the point where
it emerges above the columella. The M. depressor mandibuli
gains some at least of its innervation from fibers of the R. jug-
ularis which pass back along the R. communicans. R. jugu-
laris seems to be purely a motor nerve, though it is possible
that it may have a small lateral line component.
The R. mandibularis externus goes cephalad, laterad and
ventrad under the ventral border of the squamosum below (in
front of) the point of attachment of the ligament curving
328 JOURNAL OF COMPARATIVE NEUROLOGY.
around to the outer surface of the squamosum. After giv-
ing a branch to the skin whose destination was undoubtedly
the lateral line sense organs, it divides into two branches, one!
passing farther caudad and mesad, so as to lie on the mesal side
of the lower jaw, between the M. submaxillaris and the skin;
the other passing to the outer side of the lower jaw. From
these two branches, evidently the lines of sense organs called
by me* gular, and oral (incl. angular) respectively, receive their
innervation. It is possible that the gular division contains com-
munis fibers as well as those destined for the lateral line organs.
The M. submaxillaris I find to be innervated by the trigeminus
(R. mandibularis internus V), in this supporting Miss Pratr*
as against RuGe.' Both divisions are subcutaneous,—i. e. ex-
ternal to all skeletal and muscular structure.
The ramus mandibularis internus, separates from the R.
mandibularis externus as it leaves its ganglion, and passes ven-
trad and cephalad, on the inner (ventral) side of the quadrate
soon passing through the suspensorio-hyoid ligament. This is
the condition ina specimen g.4 centimeters in length. In
younger specimens the nerve seems to lie on the outer side of
the ligament, though very closely applied to it. Beyond the
' This is evidently the branch described by VON PLESSEN and RABINOVICZ
(Die Kopfnerven von Salamandra maculosa im vorgeriickten Embryostadium,
1891) as ‘‘Begleiter des R. hyoideo-mandibularis (h. m’)’’—Hyomandibularis
accessorius. By some these branches have been incorrectly called Rami man-
divularis internus (alveolaris) and externus. The homology of either of these
nerves with the chorda tympani, suggested by HERRICK in his ’94 paper (Am-
blystoma punctatum) and accepted by KINGSLEY ’o2, for Amphiuma, can, of
course, hardly hold now. COGHILL calls these, Rami mentales externus and
internus.
2 "95, KinGspury, B. F. The Lateral Line System of Sense-organs in some
American Salamanders, and Comparison with the Dipnoans. Proc. Americ,
Micr. Soc., Vol. XVII, 1895.
: 98, Pratt, JULIA B. The Development of the Cartilaginous Skull and
of the Branchial and Hypoglossal-Musculature in Necturus. A/orph. Jahrb.,
Bd. XXV, 1898.
*°96, Rucr, G. Ueber das peripherische Gebiet des Nervus facialis bei
Wirbelthieren. Festschrift fiir Carl Cegenbaur, 1896, pp. 195-348.
Kincspury, Columella Auris and N. Facialis. 329
ligament, the nerve is on the inner side of the M. depressor
mandibuli, MECKEL’s cartilage and the os articulare successively.
It is separated by connective tissue from the mucous membrane
of the mouth which it gradually approaches, lying on the
dorsal (mandibular) side of the depression’ between the hyoid
and mandibular arches. At about the level of the caudal bor-
der of the eye, it divides into two branches, one of which con-
tinues forward on the inner side of the jaw, the other moves
farther ventrad and mesad ; both, however, become compressed
between the M. submaxillaris and the oral mucous membrane
of the floor on the mouth between the hyoid (tongue) and the
mandible.
No communication occurs between this nerve and the Ra-
mus mandibularis internus of the fifth.
In the larvae of Spelerpes” and Desmognathus the relations
of the four main branches of the seventh nerve are in general
essentially as in Necturus. The Ramus jugularis, however, in-
stead of curving around the dorsal border of the otic division
of the depressor mandibuli as in Necturus, in Spelerpes passes
through that division of the muscle, while in Desmognathus, it
passes under the entzve muscle. In both Desmognathus and
Spelerpes it contains a cutaneous— undoubtedly lateral line—
component which was not found in Necturus. Asin Necturus the
M. depressor mandibuli receives its innervation from fibers that
accompany the Ramus communicans. The relation of both
the R. jugularis and the R. communicans to the stilus colum-
ellae has been spoken of in connection with that structure.
l“The R. alveolaris VIL, composed wholly of communis fibers, follows
the posterior border of the suspensorium to the angle of the jaw. Along this
part of its course, the R. alveolaris lies mesially of the hyo-suspensorial liga-
ment, and anteriorly of the deep pharyngeal evagination which represents the
embryonic spiracular cleft.’’ ’02, CoGHILL, G. E. The Cranial Nerves of
Amblystoma tigrinum. /Journ. Comp. Neurol., Vol. XII, p. 228.
2 The branches and distribution of the facialis in the larval Spelerpes have
been correctly given by Miss M. A, Bowers: The Peripheral Distribution of
the Cranial Nerves of Spelerpes bilineatus. Proc. Am. Acad. Arts and Sct.,
Vol. XXXVI, 1900.
330 JOURNAL OF COMPARATIVE NEUROLOGY.
The Ramus mandibularis externus passes cephalad and
laterad around the lower edge of the squamosum to its outer
surface, where it divides into branches, as in Necturus, one of
‘which curves ventrally over the outer,surface of the M. depres-
sor mandibuli and its tendon to run forward upon the ventral
surface of the M. submaxillaris. The other division runs ceph-
alad upon the outer side of the lower jaw. Both seem to be
purely lateral line nerves.
The R. mandibularis internus separates from the externus
at the cephalic border of the ganglion and goes laterad cephalad
and ventrad immediately to the mucous membrane of the oral
cavity between the hyoid arch and the quadrate and (farther
cephalad) the mandible. In the first part of its course it lies
in the connective tissue between the oral mucous membrane,
the quadrate and the M. depressor mandibuli, the quadrate
lying dorsally and the muscle laterally. Farther cephalad it
passes on the inner side of the suspensorio-hyoid ligament,
MECKEL’s cartilage and the os articulare on whose mesal side it
divides, one branch passing through a canal in that bone to
join the R. circumflexus V,' which at nearly the same level
passes between the os dentare and MeEckeEL’s cartilage. This
soon divides on emerging from its canal into the R. submax-
illaris and R. mandibularis internus V. The remainder of the
R. mandibularis internus VII runs forward between the mucous.
membrane and the mandible. At the level of the appearance
of the M. submaxillaris, it is compressed between that muscle
and the mucous membrane of the floor of the mouth. The
portion of the R. mandibularis internus VII which joined the
trigeminus I was unable to trace. I was unable to trace the
fibers of the R. mandibularis internus in any of the forms even
into the neighborhood of taste buds. It is clear, that the R.
mandibularis internus (alveolaris) in Urodeles has practically
the same course, the only marked differences being that in
Necturus, and Proteus, it does not pass through a canal in the
1T use the name applied to the comparable nerve in the frog, believing
them homologous. Compare, however, COGHILL, op. cit., pp. 265 and 266.
Kinespury, Columella Auris and N. Factalis. 331
Os articulare (angulare ?), while in Amphiuma,' (’02, KinesLey),
Desmognathus and Spelerpes, Amblystoma, Salamandra and
Triton, (CoGHILL, op. cit., p. 269), it occupies such a canal.
In Necturus, Proteus, and Amphiuma (KINGSLEY) it does not
anastomose with the Vth, while in the other forms it does.
From the above relations it is seen that the only nerve
which can be considered as a homologue of the chorda tympani
is the Ramus mandibularis internus VII which goes to the mu-
cous membrane of the floor of the mouth between the hyoid
and mandibular arches.” This, of course, is the homology
already advanced by Gaurp,* Srrone! and others, Gaupp from
morphological relations, SrronG from the character of the fibers
and their destination. AtLtis,° HERRICK® and GREEN’ have since
seen reason todoubt the homology on the grounds of the pre-
trematic position which the homologue of the chorda tympani
must have, the nerve identified by them as R. mandibularis
internus facialis being a post-spiracular nerve, and a Ramus facialis
pretrematicus being chosen by them as the homologue of the
chorda tympani.
192, KINGS).EY, J. S. The Cranial Nerves of Amphiuma. T7/ts College
Studies, No. 7, pp. 293-321.
2 RUGE (op. cit., p. 294) recognizes this nerve as the chorda tympani though
he does not identify it as the internal mandibular (alveolaris, FISHER) but seems
to find that also present as a cutaneous nerve. COGHILL (op. cit.) regards it
as a homologue of the chorda tympani.
393, Gaupp, E. Beitrage zur Morphologie des Schidels. I. Primordial
Cranium und Kieferbogen von Rana fusca. Morph. Arbetten herausg. VON G.
SCHWALBE, Bad. II.
4°95, STRONG, O. S. The Cranial Nerves of Amphibia. A Contribution
to the Morphology of the Vertebrate Nervous System. Journ. of Morph., Vol. X-
5’97, ALLIs, E. P. The Cranial Muscles and Cranial and first Spinal
Nerves in Amia calva. /ourn. of Morph., Vol. XII, No. 3, 1897.
6 99, HERRICK, C. J. The Cranial and First Spinal Nerves of Menidia ;
a Contribution upon the Nerve Components of the Bony Fishes. /Journ. Comp.
Neurol., Vol. 1X, 3-4.
7‘o0, GREEN, H. A. On the Homologies of the Chorda Tympani in
Selachians. /Journ. Comp. Neurol., Vol. X, 4-
332 JOURNAL OF COMPARATIVE NEUROLOGY.
The question seems to me to involve the correctness of the
interpretation of the chorda tympani as pretrematic, and the
homology of the mandibularis internus VII, in Menidia, Amia
and Selachia, which appears to have a course somewhat different
from that of the branch in Urodeles. For a comparison of the
relations in fishes and Amphibia, the effect of the morpholog-
ical differences in the suspension of the jaw and the value of
the relation of nerves to skeletal structures in determining their
homology, are involved; and for the larger question of the
chorda tympani, the homology of the sound-transmitting appa-
ratus in the different classes, as well; so that it seems to mea
close consideration of homologies is yet premature.
The pre- or post-trematic origin of the R. mandibularis
internus in Urodeles cannot, of course, be determined, since
the first gill cleft does not come to development. From its
point of origin and course, it certainly could be pretrematic, as
Coxe’ has pointed out, and it seems to me the possibility that
this nerve represents a pre-trematic nerve such as GREEN,
(e. g.) described in Selachia,? is worth considering. In this
connection the different relations of the facial nerve and col-
umella auris in Anura and Urodela must also be considered.
There is here presented in allied forms, a difference of relation
1°96, CoLE, F. J. On the Cranial Nerves of Chimaera monstrosa (Linn)
with a Discussion of the Lateral Line System and of the Morphology of the
Chorda Tympani. 7Zyvamns. Roy Soc., Edinburgh, Vol. XX XVIII, Pt. II,
(No, 19).
21 have already referred to the statement by COGHILL (p. 228) that this
nerve could be considered pre-trematic. In the forms studied by me, however,
the conditions, I believe, hardly warrant a definite conclusion. COGHILL,
even, would regard the R. mandibularis internus in Urodela and Anura, as not
homologous (p. 265), and this, too, seems to me rather extreme. The entire
hyomandibular nerve in the frog crosses over and behind the columella auris
and in Urodela under and in front of it. As stated in a previous paper (’95,
The Structure and Morphology of the Oblongata in Fishes; Journ. Comb.
Neurol., Vol. VII, p. 30) where I quote also the opinion of Miss PLATT to that
effect, I feel that the origin and distribution of a nerve are of more importance
than its course, which may vary, and consequently should not be too closely
made the basis of homologies. We also see that the relation of a nerve to a
muscle cannot be relied upon as a test.
Kincssury, Columella Auris and N. Facials. 333
of nerve to skeletal structure of extreme type. As is well
known,' in the frog the hyomandibular nerve crosses above the
columella and passes down behind it to its destination, whereas
in Urodeles it passes in front of or below the same structure.
Other cases of similar differences of relation in this region,
mentioned in this paper, are (a), the relation of the jugular
nerve in Necturus on the one hand and in the other salamanders
investigated on the other hand; in the first case it passes above
the columella (stilus columellae), in the second, below. (b),
Necturus also offers a difference in the relation of the internal
mandibular branch to the quadrato-hyoid ligament. In Des-
mognathus and Spelerpes the nerve passes on the inner side of
the ligament; in Necturus, through the ligament, or on its
outer side in younger individuals. Further (c), the R. jugu-
laris in Necturus passes over the depressor mandibuli; in
Spelerpes larvae, through it; in Desmognathus larvae, under it.
The differences, in the last two cases at least, it seems to
me, might possibly be explained on a more or less mechanical
basis. The nerves (and muscles) are already developed and
their course and positions established before the anlage of the
columella or that of the quadrato-hyoid ligament has appeared,
and the relations the latter structures assume when they do
develop, has been determined for them by the position of the
structures earlier developed. This explanation would not, of
course, be an ultimate one.
The nomenclature employed in the above descriptions is
that suggested by Professor Gaupp. Columella, including
operculum and its process, sti/us columellae, which may be
joined to the suspensorium by an appreciable ligament—/ga-
mentum suspensorto-columellare (operculare). \regard the sus-
pensorio-columellar (opercular) connection in the forms studied
as homologous. The term stilus columellae is used in describ-
193, Gaupp, E. Beitrage zur Morphologie des Schadels. I. Primordial
Cranium und Kieferbogen von Rana fusca. Morph. Arédeten, herausgegeben von
G. Schwalbe, Bd. II.
’99. ECKER’s u. R. WIEDERSHEIM’S Anatomie des Frosches, auf Grund
eigener Untersuchungen durchaus neu bearbeitet. [II Abth. 1899,
334 JOURNAL OF COMPARATIVE NEUROLOGY.
ing the relations in Desmognathus and Spelerpes, in view of
the structure in the adult, despite the fact that the ‘‘stilus”’
probably begins as a chondrification in the cord of cells extend-
ing from the operculum to the squamosum. This point of a
separate chondrification, however, has not been firmly estab-
lished. In that case the ligamentum squamoso-columellare
(operculare) and the stilus columellae of Spelerpes I should
regard as homologous—despite the different relations to the
facial nerve.
In conclusion, I may say that the points which I wish to
emphasize are:
(1) The primary connection of the columella with the
bone which I regard as the squamosum.
(2) The different relations of the facial nerve to the
(‘‘squamoso-opercular’’ connection) stilus columellaris in the
frog, Necturus (and Proteus) and other Urodela.
(3) The secondary nature of the connection of the col-
umella with the quadrate cartilage, where such connection
occurs.
(4) The different relations of the ramus jugularis VII, to
the musculus depressor mandibuli in Necturus, Spelerpes, and
Desmognathus.
(5) The course and relations of the R. mandibularis
internus VII, in view of the possible homology with the™
chorda tympani.
(6) The question of the value of. the relation of a nerve
to skeletal parts and muscles, as a criterion of homology.
Anatomisches Institute, Fretburg 1. B., May 1, 1902.
Cornell University, Sept., 1903.
EDITORIAL ANNOUNCEMENT.
THE JOURNAL OF COMPARATIVE NEUROLOGY, as originally
announced, was open to contributions in the field of compara-
tive neurology, physiology and psychology. The founder, feel-
ing that the time was ripe for a more thorough correlation of
the facts in these different fields, planned to devote the Journal
as much to the functional as to the structural study of the ner-
vous system. During the thirteen years of the existence
of the Journal of Comparative Neurology, the functional
side of neurological work, although not wholly neglected,
has received far less attention than was originally contemplated,
chiefly on account of the continued ill-health of the Editor-in-
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parative psychology.
Now, however, we are able to announce an enlargement of
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sentation of the functional as well as the structural aspects of
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The Journal will hereafter be known as the ‘‘Journal of
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of the editorial staff remains in general as before save that Dr.
Rosert M. YERKEs of the Department of Psychology, Harvard
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The attention of psychologists, physiologists and medical
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336 JOURNAL OF COMPARATIVE NEUROLOGY.
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of value in the materials published, for in addition to the recog-
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stood structurally by a study of its phylogeny, it is now clear
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For morphologists the Journal will continue to be, as in.
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EPRERARY NOTICES:
The Relations of Biology and Psychology.'
The book before us has already been reviewed by a number of
writers and needs no introduction to the readers of this journal. The
purpose here is simply to touch upon certain points (not dwelt upon at
length by any of these reviewers) which are of interest at once to the
psychologist and to the biologist.
(1) Psychophysical Evolution. ‘The papers which are here gath-
ered together may be treated, says the author, ‘‘as each dealing with
a narrower question, yet as having reference to the larger problem
which may be called psychophysical evolution—the evolution of mind
and body together” (p. 2). This conception of psychophysical evolu-
tion is one to which the author returns again and again throughout the
book in a way which is stimulating or exasperating according to where
the reader stops in in the perusal of the book.
One at first feels that the author has struck out the true solution
of a perplexing question, and he turns the pages expectantly until he
shall come to the convincing presentation of this great thought. But
as he proceeds all that he finds is the cheerful assumption that this has
already been made as clear as is necessary—and this is the source of
the feeling of exasperation.
The clearest brief statement of the principle of psychophysical
evolution is that in which the author says that ‘‘the brain not a brain
when consciousness is not there,” and ‘‘consciousness does not, on the
other hand, produce movement without a brain” (p. 130). This most
promising suggestion leads the reader to the natural conclusion that
the author has in the background a point of view which justifies what
appears upon the surface as a rather paradoxical juxtaposition of con-
cepts usually kept quite distinct. ‘What is this point of view?
; We all, doubtless, today, feel that brain and consciousness are
equally genuine and valid phases of the reality of experience; and
1 BALDWIN, J. MARK. Development and Evolution: Including Psycho-°
physical Evolution, Evolution by Orthoplasy, and the Theory of Genetic
Modes. The Macmillan Co., New York, 1902.
xxx JOURNAL OF COMPARATIVE NEUROLOGY.
this has been stated in many metaphors and similes. We are all either
asking the question ‘‘why the mind has a body” or why the body ever
came to have a mind. But what we still lack is an analysis of the
origin and meaning of the distinction—its genesis and its function.
Why do we distinguish between brain and consciousness at all, if ulti-
mately they are so intimately one? Just how is their difference related
to their identity ? How did the distinction originally come to be set up,
and what modifications has it undergone in the history of scientific
thought ?
(2) The Psychological and the Biological. The author's discus-
sion of the terms ‘‘psychic” and ‘‘psychological” (Chap. I, §2) is a
hint of such an analysis. In this section Professor BaLDwIN distin-
guishes between the ‘‘pyschological” and the ‘‘psychic” as follows:
‘By the psychological I mean the mental of any grade, wewed from
the outside ; that is, viewed as a definite set or series of phenomena in
a consciousness, recognized as facts and as ‘worth while’ as any other
facts in nature.” ‘‘This occurrence of a psychological change in an
animal is a fact in the same sense that the animal's process of digestion
is’ (p. 4). ‘‘The discussion of the respective spheres of these two
sciences turns upon a distinction of points of view. On the one hand
the psychologist as such, and for his science, must aim at the recogni-
tion only of the facts which are psychic or mental; that is, of such as
are facts to the consciousness iz which they occur. ‘These alone are
psychic, and these belong to individual psychology” (p. 5). ‘‘Psychol-
ogy, when considered as the science of mind,—that is, looked at from
the objective point of view,—takes cognizance of the ‘psychonomic’ ;
but when considered as a subjective science, as interpreting its own
data, it does not; but, on the contrary, it confines itself to the psy-
chic” (p. 8).
By way of criticism of this, the question at once arises whether
there is any such thing as psychology ‘‘considered as a subjective
science” ? Many other writers have been insisting that there is no
‘individual psychology” in this sense; there is no science of the indi-
vidual. From this point of view, the ‘‘psychologist as such’' is no
scientist at all; the attempt to draw a distinction between two kinds of
psychology in this sense proves suicidal. If the difference ‘‘turns upon
a distinction of points of view,’’ then it does not turn upon a distinc-
tion of contents; if it is a distinction of method only, then it is
not a distinction of subject-matter. When we take up ‘‘the stand-
point of the observer, that of the scientific man who _ essays
to investigate some one else’s consciousness, or that of an animal,
Literary Notices. XXX
the procedure is now subject to different rules and limitations” (p. 5)
it is true, but this is essential to any science of psychology; this is not
another kind of psychology over and above so-called ‘‘individual psy-
chology.” Individual psychology is not scientific psychology apart
from this. There is no sczence of psychology which deals with the
strictly psychic.
Moreover, this view gets the author into difficulties when he
comes to apply it to his doctrine of psychophysical evolution. ‘‘But
now, and this is the essential point to remark in our present connec-
tion, so soon as we ask the psychophysical question of genesis,—that
of the development and evolution of mind and body taken together,—
pursuing the biogenetic method, this limitation no longer rises. to
trouble us. We include all psychophysical facts as such in the defini-
tion of our science. Changes in mind and body go on together, and
together they constitute the phenomena. Both organic and mental
states and functions may be appealed to in our endeavor to trace the
psychophysical series of events of such, since both are objective to the
spectator, the scientific observer’ (p. 8). Accordingly, ‘‘with the gen-
eral understanding now arrived at, we may take a preliminary survey
of the field in the light of certain current hypotheses. Among these
is what is known as ‘psychophysical parallelism’ ” (p.1o). ‘‘The prin-
ciple of parallelism assumed, we claim once for all the right fo neglect
the relation of the two terms, mental’ and physical, in all circumstances
whatsoever” (p. 15).
But how can we interchange the psychical and the physical if,
by definition, the psychic facts are facts only ‘‘to the consciousness in
which they occur?” The law that ‘‘for science all facts are equal’
does not mean that the physical and the psychical can be interchanged
without changing the ‘‘point of view.’’ And if the author here does
not mean the psychical by his term ‘‘mental,” then how does the dis-
cussion become relevant to the doctrine of psychophysical parallelism ?
What Professor BALDWIN seems to mean is that the same process
of psychophysical evolution may be stated either as psychological or
as biological, i. e., it may be interpreted from either of these egually
objective points of view. But this has nothing in common with the doc-
{rine of psychophysical parallelism. The latter, as he says elsewhere,
is a question of ultimate philosophical interpretation, while the former
is a question of division of labor in scientific method. Not that the
' Note that the ambiguous term ‘‘mental,” so important at this juncture, is
not defined. Does the author here mean “‘psychic’’ or ‘‘psychological ?”’
XXX JOURNAL OF CoMPARATIVE NEUROLOGY.
question of methodology does not have an important bearing upon this
question of the distinction between the psychical and the physical, but
this relation can not appear as long as one member of the distinction
is taken as fixed.
(3) The Place of Consciousness in Evolution. The place of con-
sciousness in evolution is the same on either the Lamarckian or Dar-
winian view. ‘This is made possible by the author's theory of organic
selection and social heredity. One of his reviewers, indeed, thinks
that he has not wholly escaped the fallacy of supposing that conscious-
ness produces causal changes in the physical world of muscles. But,
besides the author’s disavowal of such a doctrine in a reply to this re-
view, he distinctly says in the work before us that there is a third view
beside the theory of automatism and the theory that consciousness is a
vera causa (p. 121).
But what is this third view ? Does the author here intend a func-
tional interpretation of the relation of the psychical to the physical ?
If there is one psychophysical system, and if consciousness is simply
the meaning of this system when it is tensional, as contrasted with the
state of the same system when in the relatively stable equilibrium of
habit, then consciousness can be included in the statement of the ante-
cedent phenomena explanatory of a voluntary movement—not indeed,
as a distinct phenomenon, but as the statement of a continuous process
in one of its stages. To say that the same movement could take place
without this state of consciousness is to say that the fact that it was a
conscious movement (i. e., had this meaning as distinct, say, from an
habitual movement) does not make it a different movement from one
which is not conscious. Any mark or character of the movement
makes it a different movement. In truth, no two movements are ever
exactly alike. Of course, you may abstract from all these differences,
but then your judgment is an hypothetical and not a descriptive one,
and here the aim, as the author says, is to secure a scientific in the
sense of a descriptive statement of the facts.
The suggestion that heredity rather than variation is the fact to be
accounted for in evolution, ‘‘that variation is normal, and that heredity
is acquired through the operation of natural selection restricting the
limiting variation” (p. 230), is, then, to be put alongside of this other
contention of the author, that consciousness, in one form, is the
growing-point of evolution from the first. Is not this tantamount to
saying that what we call consciousness is the variable element in devel-
opment and evolution, that consciousness represents the shifting area
of tension in adaptation, or, to put it from the other side, the moving
Literary Notices. XX Xili
equilibrium, or struggle toward equilibrium, between the forces of the
organism and the environment ?
(4) Mind and Body. The problem of the relation of mind and
matter, from this standpoint, becomes chiefly a question of the logic of
scientific method. The present writer has elsewhere (PAzlosophical
Review, May, 1903) suggested, that this is the consistent interpretation
of Professor BALDWIN’s chapter, in the book before us, on ‘‘Mind and
Body.” The psychical ceases to be an entity in any sense of the term,
even in the sense of energy. Instead of the psychical being subor-
dinated to the concept of energy, as Professor OstwaLp contends, or
being regarded as interchangeable because universally parallel, as Pro-
fessor BALDWIN contends, these concepts must, in time, be recon-
structed in terms of each other, and take their place in a scientifically
continuous series, the terminology of which remains to be worked out,
but of which it is the great distinction of Professor BALDWIN to have
given a hint in his otherwise paradoxical doctrine of psychophysical
evolution. Another hint in the same direction is the recent attempt to
define the meaning of the psychical by Professor GEorcE H. Mean,
in the University of Chicago Decennial Publications, Volume III,
where the psychical is defined as the process, as contrasted with the
content, of the experience, or, to use the terms of logic which he
employs, the psychical is identified with the copula of the judgment.
H. HEATH BAWDEN.
The Psychology of Action.'
We have in this book what we have learned always to expect from
the pen of its distinguished author, a lucid, interesting and original
presentation of the principles of psychology. Its originality consists
in the successful employment of terms chosen from the sphere of
practical life, as the leading categories and principles of division. In-
stead of the traditional classification of the subject-matter under the
rubrics of cognitive, affective, and conative states, we have the re-
freshing consciousness of feeling that we follow the meaning of the
author from the beginning without being involved in a system of tech-
nicalities. He discusses mental life under the headings of Sensitive-
ness, Docility, and Initiative. These terms retain the content which
they have in ordinary life while at the same time serving the purposes
1 Outlines of Psychology; An Elementary Treatise with Some Practical
Applications. By JosIAH Royce, Ph. D., LL.D. Mew York, Macmillan Co.,
7903. (In the Teachers’ Professional Library series, edited by President
NICHOLAS MURRAY BUTLER.)
XXXIV JOURNAL OF COMPARATIVE NEUROLOGY.
of an accurate psychological analysis. The main discussion under
these heads is preceded by four chapters entitled respectively: ‘‘In-
troductory Definitions and Explanations,” ‘‘The Physical Signs of the
Presence of Mind,” ‘‘The Nervous Conditions of the Manifestation
of Mind,” ‘‘General Features of Conscious Life.” The author then
proceeds to discuss the three chief forms of Sensttiveness, viz: ‘‘Sen-
sory Experience,” ‘‘Mental Imagery,” ‘‘The Feelings.” The aim
here is to ‘‘make a summary statement of the principal kinds of states
of consciousness that occur within the range of our psychological ex-
perience,” considered especially with relation to the sorts of physical
conditions upon which they depend. ocility is treated in five chap-
ters. This is the study of the ‘‘relations that bind the consciousness
of any moment to previous experience.” ‘The ‘‘General Law of Do-
cility” is the law of habit which is traced through its various exempli-
fications in ‘‘Perception and Action,” ‘‘Assimilation,” ‘‘Differentia-
tion,” and ‘‘Imitation,” which introduces to us ‘‘The Social Aspect of
the Higher Forms of Docility.” /ztiative is discussed in a single
chapter entitled: ‘‘The Conditions of Mental Initiative.” This is
followed by two concluding chapters: ‘‘Certain Varieties of Emotion-
al and Intellectual Life,” ‘‘The Will or the Direction of Conduct.”
In general standpoint this book may be regarded as a contribu-
tion to what is coming to be called the functional point of view in
psychology. This is seen in the insistence upon the integrity of ex-
perience, in the valuable critique of the doctrine of conscious elements
as employed by the structural psychologist, and in the use throughout
of the biological conception of habit, and even of consciousness, as
special developments within the life of the organism for the sake of
enabling it to adjust itself in its changing environment. Probably the
author did not have this last point so explicitly in his aim as might be
inferred from the statement just made, but it is only the more signifi-
cant if such is the case. Hints of it are scattered throughout the
book without any more explicit statement being made than that em-
bodied, for example, in the following sentences: ‘‘The central pro-
cesses which our images accompany form themselves a part of our
reaction to our environment, avd our more organized sertes of mental
images actually form part of our conduct’ (p. 160).' ‘‘Thought is either
action or nothing” (p. 351). Here is the gist of the functional point
of view, that all the various forms of consciousness are special devel-
opments zwéhzn action, and, therefore, special developments of action.
1 Ttalics ours.
Literary Notices. XXXV
As this, to the present reviewer, is the most significent feature of the
entire treatment, it may be instructive to show in what ways action is
here made fundamental.
(1) The author says, ‘‘Fhe single facts of sense, and the single
movements which we make, are always related to, or, as one may say,
are differentiations of our general orientation” (p. 147). This is con-
nected with the ‘‘tropisms of orientation.” ‘‘The reactions of orien-
tation are among the most fundamental phenomena of healthy life.”
‘Our sensory experience at any moment will stand partly for our more
general activities of orientation, and partly for our more special reac-
tions to individual objects” (p. 143). ‘‘The special acts are always
superposed upon the general acts.” ‘‘All our particular sensory ex-
perience will be related, not only to our special acts, but to our gen-
eral acts of orientation, and to those experiences which result from
these acts.” <‘‘All such sensory experiences appear to our con-
sciousness as facts existent within a certain primitive whole, which,
apart from differentiation, is our experience of the general orientation
of the entire organism” (p. 146). The author, in other words. is in-
sisting that our motor or kinaesthetic experiences (sensations and
images) form the very core of consciousness. The kinaesthetic sensa-
tions supply the fundamental imagery of meaning. This is equivalent
to saying that action is the fundamental category of experience and the
various forms of conscious experience are special developments within
this. Here, by the way, was an excellent opportunity to clear away
at a stroke the whole difficulty of the relation of the psychical to the
physical, in so far as psychology is concerned, since consciousness
here appears simply as action passing through a tensional or recon-
structive stage. ‘‘Tension,’’ he says on a previous page, ‘‘the mu-
tual opposition and balancing of numerous tendencies, is absolutely
essential to normal life.” Why should consciousness any more than
habit be hypostasized, if both are equaliy developments of action ?
(2) The statement which the WeBEeR-FECHNER law receives Js a
good illustration of the tendency to interpret experience from the
standpoint of the act, from the standpoint of the organic circuit, as
the functional psychologists would say, rather than from the standpoint
of any one of its contained minor activities. ‘‘The law is that in
order that differences of sensory experience should have, in two differ-
ent cases of comparison, the same value for our reacting consciousness,
or should appear to be equal differences, the stimuli that are compared
in the two different cases must differ from one another, not by the
same absolute physical difference in their magnitude, but by the same
XXXVI JOURNAL OF COMPARATIVE NEUROLOGY.
relative difference’ (267-8). ‘‘The psycho-physic law appears now
to formulate a certain limit to which the Docility of the organism in
responding to finer differences in stimulation is subject” (270). That
is, ‘‘the psycho-physic law is not a law directly relating to our sensa-
tions, but is rather a law of our reactions” (272).
(3) In chapter XII we have a most illuminating statement of the
relations of thought to action in a discussion of the psychological and
social functions of language. Thinking differs from naive action
chiefly in this, that in thinking we reflect on the details of the action,
and bring the method of the action to consciousness. ‘‘One who
thinks makes it part of his ideal to be conscious of how he behaves in
the presence of things. And this he does because the social compari-
son of his acts with the acts of other people not only controls the for-
mation of his acts, but has made his observation of his own acts an
ideal’ (284). ‘‘The consciousness of how one performs the act” is
the very essence of thought. The abstract idea or concept is a re-
duced act. Take the concept or ‘‘horse” or ‘‘man.” ‘‘Whoever
knows what a horse or man in general is, knows of some kind of act
which it is fitting to perform in the presence of any object of the class
in question.” ‘*The name ‘man’ or ‘horse,’ the word-image asso-
ciated with any such subject, is itself a part of a well-known act by
which one may react in the presence of an object in the class in ques-
tion.- For naming objects is one way of responding to their presence”
(286-287). ‘‘Our general ideas . . . stand, therefore, for cer-
tain. . . attitudes.” ‘‘Our mental images of outer objects are
never to be divorced from our reactions.”” A ‘‘general idea is a con-
scious plan of action.”
(4) The treatment of the relation of feeling to action supports the
same general conception. On page 296 we read, ‘‘Like the thinking
process in general, the reasoning process develops out of conditions
which at the outset involve a very rich, and in fact predominant pres-
ence of feelings and of Complex emotions. That is, reasonings have
resulted from what were at first decidedly passionate contrasts of
opinion.” ‘Thinking, reasoning, here would appear at the setting up
of distinctions and the introduction of control within the primitive
predominantly affective type of consciousness. In the chapter on the
Feelings the author refers to the traditional view of the relation of
feeling to thought and to action as embodying an important truth, but
seems hesitant about adopting it. ‘‘Those who “divide mental life, in,
the well known traditional way, into the life of cognition, the life of
feeling, and the life of will, are accustomed to assign to the feelings a
Literary Notices. XXXVil
stage intermediate between the life of cognition and the life of will.
From this point of view our cognitive consciousness first furnishes to
us the facts. In terms of our feelings we estimate the va/ues of these
facts for us. In view of these values our acfs are determined. ‘That
this traditional view has a real significance cannot be questioned. But
in the present exposition of the structure and laws of consciousness
we are not at all closely following the lines of the traditional exposi-
tion” (164). Now the reviewer ventures to suggest that this tradi-
tional view, with one modification, stands more in line with the general
method of treatment pursued in this book than does the exposition
actually given. On another page (226), the author says that in ordi-
nary association ‘‘ the perception is relatively instantaneous.” ‘‘ The
present sense disturbance is at once associated with a consciousness
due to already established motor habits” (225). This suggests the real
significance of the traditional view—which holds that we first perceive
something, then feel interested in it, and then act upon it—only the
traditional view regards this as a conscious act of perception, whereas,
in truth, this initial perceptive act is automatic, instinctive or habitual.
It is a good illustration of one of those “attitudes” to which the
author refers elsewhere. ‘The traditional view is true except that the
cognition which comes first is not conscious or reflective but instinc-
tive or intuitive. And the consciousness, which the author says ac-
companys our acts, or takes place ‘‘ side by side with the tendencies
to action” (164), from this point of view is rather developed within
the action at the point where and because of the fact that this instinc-
tive perceptive habit fails to meet the exigencies of some situation.
Thus is evolved first an emotional consciousness and then within this,
as we have already seen, an intellectual consciousness (in this case,
conscious cognition) which defines and controls this emotion. From
this standpoint feeling is just unanalyzed consciousness; it is total,
vague, impulsive consciousness; hence the significance of the analysis
of emotion into organic, kinaesthetic and dermal sensations.
(5) Initiative, attention, apperception, self-activity, are all traced
back to elemental tendencies, instincts or tropisms, operating ‘‘at times
when the results are not immediately adaptive.” If the adaptation
were perfectly smooth and unimpeded there would be no need for the
evolution of such phenomena as attention and initiative. These are
the product of, and are developed to meet the necessities of disadap-
tation in experience. The orderly control of experience in attention
and direction of experience in so-called self-activity are the result of a
selection from among a great number of still unadaptive movements
XXXViill JoURNAL OF COMPARATIVE NEUROLOGY.
in which the animal persists despite their inefficiency. This is what
Professor BALDWIN has called functional selection from excess move-
ments or over-production of variations in the individual. Important
questions arise at once to some of which an answer is given in chapter
XIII. Why are these tropisms not immediately adaptive, and why do |
animals persist in making these non-adaptive movements ? Why should
such conscious processes as attention develop thus at the points of dis-
adaptation in experience ? What is the psychology of this disadapta-
tion or break inthe experience? And, even more important, the
psychology of the reconstruction or readjustment after the break, by
means of the conscious attention thus evolved. Professor ROoycE an-
swers the first of these questions by saying that ‘‘this factor, this pecu-
liar persistence, belongs to the temperament of the animal” (315). He, I
suppose, would hasten to add that this is no real explanation, since
‘‘temperament” is something itself to be explained rather than the
- explanation of anything. Would it be in line with his own argument
to suggest that the approximate reason is that the ordinary inhibitory
effect of the regular routine of habitual acts is removed. The animal
is, so to speak, reduced to a state of psychoplasm or impulse because
of the ineffectiveness of the customary modes of activity. The rest-
lessness and persistence in unadaptive movements represent simply
the releasing of tendencies which are ordinarily inhibited. Relative
freedom from ordinary restraints results in a relapse into a compara-
tively primitive state of unmediated impulse, until new restraints can
be established, new habits built up. This gives us a hint, at the same
time, as to the true nature of the break or disadaptation and a sugges-
tion as to the law of the readjustment or reconstruction. Apart from
some such interpretation, one is impelled constantly, throughout this
whole discussion of initiative, to ask the old question, whether there
is ever any absolutely novel element in experience, and, if not, how
there can be any real progress.
(6) One’s feeling, after reading this delightful book, is one of satis-
faction in finding the emphasis thrown once again upon the unity and
continuity of experience, after so much analysis and dissection in re
cent psychology, but with this, perhaps out of it, springs a desire that
the author had carried out his organic view of experience a little further
and shown us, not only that action is the natural consummation of feel-
ing and thinking, but also how feeling and thinking first appear because
of the interruption of action. It is just the full appreciation of the
significance of this emergence of consciousness within action, as itself
a phase of action—that consciousness not only leads over into action
Literary Notices. XXXIX
but arises from and within action—that is most needed at the present
time to put psychology into right relations with biology, on the one
side, and with philosophy, on the other. With biology, because
herein we find a category common to both sciences—the category of
action, of adaptation, or adjustment and readjustment. With philos-
ophy, for a similar reason, that in the process of the reconstruction of
experience we see the true functional significance of the psychical.
One of the best features of the book before us is its insistance on the
social character of consciousness, and upon the psychical individual
as the centre for the initiation of new and progressive phases of social
life. ‘‘Certainly a general view of the place which beings with minds
occupy in the physical world strongly suggests that their organisms
may especially have significance as places for the initiation of more or
less novel types of activity” (301). ‘‘Social inventiveness depends
upon individualistic restlessness” (327).
A recent writer has said that ‘‘we ought to turn our views of hu-
man psychology upside down and study what is now casually referred
to in a chapter on habit or on the development of the will, as the gen-
eral psychological law, of which the commonly named processes are
derivatives.” This Professor Royce has done in a way that will prove
instructive to psychologists as well as to teachers.
H. HEATH BAWDEN.
The Fore-Brain of the Bird.'
The bird presents in its brain as in other features of its organiza-
tion more marked specialization than is to be found in any other class
of vertebrates. The bird brain has been the subject of comparatively
few researches and our knowledge of its structure and of the signifi-
cance of its several parts has been meager. In the fore-brain, especi-
ally, great difficulties to a right understanding of its morphology and
physiology have been presented by the unusual size of its basal gan-
glion and the apparent absence of a true pallium over a large part of
the fore-brain. The homology of the several parts of the basal gan-
glion, the extent, structure, and the connections of the pallium and
the functional significance of the several areas or nuclei are perplex-
1 Untersuchungen iiber die vergleichende Anatomie des Gehirnes, von Dr.
Lupwic EDINGER in Frankfurt a. M. 5. Untersuchungen tiber das Vorderhirn
der Végel in Gemeinschaft mit Dr. A. WALLENBERG in Danzig und Dr. G. M.
Ho.tMeEsin London. Mit sieben Tafeln und elf Textabbildungen. Sonderabd.
aus d. Adhdlgn. d. Senckenb. naturf. Gesellschaft, BA. XX, Heft IV.
sol JOURNAL OF COMPARATIVE NEUROLOGY.
ing questions to the solution of which Dr. EpinGer has applied him-
self during several years. The very satisfactory results published in this
paper EDINGER attributes in large part to the codperation of WALLEN-
BERG and Hotmgs, which made it possible to study a very wide range
of material, representing all the chief types of birds, and to study the
course of fiber tracts by the degeneration method... The attempt
to describe the centers and fiber tracts in so complete a manner that
they may be recognized in any group of birds, may be regarded as
fairly successful.
The key to the interpretation of the bird fore-brain is found in its
development. ‘The fore-brain in the early embryo presents the typical
arrangement: a thick ventral wall formed by the basal ganglion and an
extensive pallium forming the roof of the wide ventricle. The basal
ganglion, however, grows much more rapidly than the pallium and
eventually obliterates a large part of the ventricle and fuses with the
pallium over the greater part of the lateral and dorsal regions. The
ventricle becomes reduced to a narrow medio-dorsal cleft connecting
occipital and frontal horns, the latter extending into the olfactory lobe.
The parts of the pallium thus fused with the basal ganglion have been
overlooked or wrongly interpreted by previous authors. It is usually
marked off from the basal ganglion by a layer of cells or by a layer of
medullated fibers—the Stabkranz—and even where it is not so marked
its structure and connections, as weil as its developmental history, show
that it is a true pallium.
In the basal ganglion the author has identified the epistriatum and
the nucleus thaeniae and their fiber tracts, the relations being essentially
the same as in the brain of reptiles. The remainder of the basal gan-
glion, which is very greatly enlarged as compared with that of any
other vertebrate, consists of a ventro-median mesostriatum, a dorsal
hyperstriatum, and a lateral ectostriatum. ‘The ventro-anterior end of
the mesostriatum is divided into two nuclei, a median lobus_parolfac-
torius and a lateral nucleus basalis. Although there are great differ-
ences in the size and functional importance of these two nuclei and of
other parts of the basal ganglion, the brains of all birds agree in the
main features. ‘The fibers from the pallium and the hyperstriatum
form a medullated fiber layer, the lamina medullaris dorsalis, over the
dorsal surface of the mesostriatum which corresponds to the capsula
interna of mammals. The fibers then pass downward through the
mesostriatum to form the brachia cerebri on its ventro-caudal surface.
A true capsula interna is occasionally present (parrot). | It is as yet
Literary Notices. xli
impossible to compare the parts of the basal ganglion of birds with the
nuclei in the corpus striatum of mammals.
Only a few of the more important facts in the arrangement of the
fiber tracts can be mentioned here. The olfactory apparatus is very
poorly developed. Only a single tract of fibers connects the lobus
olfactorius with the rest of the fore-brain and the destination of these
fibers is not described. ‘The nucleus thaeniae sends a bundle to the
ganglion habenulae. This is joined by a bundle from the occipital
cortex (tractus cortico-habenularis) and by one from the more anterior
portion of the basal ganglion. This bundle, which is not commented
upon by the author, suggests the anterior portion of the tractus olfacto-
habenularis, as it has been described in fishes. No tract which can
certainly be considered as fornix has been found. The greater number
of fibers, both ascending and descending, connecting the fore-brain
with the thalamus are related to the striatum and not to the pallium.
Especially interesting is a tract from the sensory nucleus of the V nerve
to the nucleus basalis of the mesostriatum and a corresponding descend-
ing tract of the oblongata and possibly to the cervical cord.
The most of the fiber bundles connecting the pallium with other
divisions of the brain are mingled with those of the striatum and are
ascending fibers from the thalamus and mid-brain. Almost the only
large descending tract from the pallium is the tractus septo-mesenceph-
alicus, from the medio-dorsal portion of the pallium to the dorsal part
of the thalamus and the tectum opticum. Its function is unknown.
A commissura pallii connects the medio-dorsal cortex of the two sides.
A tract connects the occipital cortex with the mid-brain beneath the
tectum opticum. ‘This bundle corresponds to the cortical optic tract
in mammals. The various portions of pallium are interconnected by
shorter and longer associational fibers. These are least developed in
the medio-dorsal cortex. Other important fiber tracts connect the
nuclei of the fore-brain with one another. The anterior commissure
appears to be purely a commissure between the two epistriata.
The experimental works of SCHRADER, GOLTz, and KALIscHER on
the functions of the bird fore-brain are reviewed, and the results ex-
tended by means of the new anatomical facts. The fore-brain is not
essential to either sensory or motor activities but exercises a directive
influence on both which raises them above the plain of simple automa-
tism. Removal of the pallium alone does not cause the bird to starve, |
unless the striatum also is injured. A certain degree of localization of
function is present in the fore-brain of various birds. The mesostria-
tum has an important relation to the act of eating, probably mediate
xhii JouRNAL OF COMPARATIVE NEUROLOGY.
by the tracts connecting it with the nuclei of the V nerve in the ob-
longata. The occipital cortex is important for sight. The median
portion of the dorsal cortex seems to be especially concerned in the
innervation of the limbs.
The text of 84 quarto pages is accompanied by eleven text-figures
and seven plates, five occupied by elegant colored figures representing
WEIGERT sections and two presenting the results of degeneration ex-
periments. The paper is one of the most important recent contribu-
tions to the morphology of the vertebrate brain.
J. B. JOHNSTON.
The Optic Chiasma and the Post-optic Commissure.
This subject has been treated in two papers by Dr. Burron D.
Myers. In the first’ the chiasma alone was studied by the degener-
ation method in the toad, cat, dog, rabbit, monkey, owl and snake, the
toad receiving the most thorough treatment. In the toad certainly and
probably in the owl and snake the decussation in the chiasma is total.
In the dog, cat and monkey the decussation is unquestionably partial.
In the second paper’ the same author makes a more thorough
study of the relations in the rabbit, using the method of v. GUDDEN.
The optic nerves and tracts do not begin to become medullated until
twelve hours after birth; accordingly enucleations of the eye made
during the first day will result in total failure of medullation of the cor-
responding optic nerve fibers and very clear pictures can be secured by
the WEIGERT method, the animals having been killed at various inter-
vals after the operation.
The experiments show conclusively that the chiasma of the rabbit
is partial, though the uncrossed fibers are few in numher. The rela-
tion of the optic fibers to the post-optic or inferior commissure can be
determined by reason of the fact that the optic nerves become medul-
lated earlier than the commissure. Comparisons of series of different
ages made after enucleation of both eyes with similar series made after
the enucleation of one eye permits an accurate study of the relations of
the optic tracts to the commissure. In brief, three such commissures
are recognized : ;
1 The Chiasma of the Toad (Bufo lentiginosus) and Some Other Vertebrates.
Zeits. f. Morph. u. Anthropologie, LLY ..225/ 1901.
2 Beitrag zur Kenntniss des Chiasmas und der Commissuren am _ Boden
des dritten Ventrikels. Archiv f. Anat. u. Physiol. Anat. Abt., 1902.
Literary Notices. xliii
1. The commissura inferior of GUDDEN, or Commissura arcuata
posterior of HANNOVER.. GUDDEN termed this the com. inferior in
transverse sections, but the com. superior MEYNERTI in horizontal sec-
tions. Its fibers are closest to the chiasma at their crossing and go out
laterally closely associated with the optic tracts.
2. The rostral part of the decussatio subthalamica anterior of
GANSER. This is GUDDEN’s commissure of MEYNERT, and it may
properly retain the name, MEYNERT’S commissure. Its crossing lies dor-
sally of the com. inferior, and its fibers also go out with the optic tracts
laterally.
3. The caudal part of the decussatio subthalamica of GANSER.
This may retain the name GANSER’s commissure. Its fibers after the
crossing run back on each side of the body nearer the median line than
either of the others and they envelop the fornix tracts laterally of the
third ventricle.
The contradictory accounts of earlier authors are carefully re-
viewed in the light of the author’s experimental results and it is to be
hoped that the conclusions reached may set at rest the synonomy of
this confusing region. It is needless to add that a real understanding
of these commissures (or decussations, as they probably are) cannot be
hoped for until we know the exact terminal relations of all the types of
neurones involved.
There is described a curious mesial slip of the optic tract which
runs up along the inner side of the inferior commissural tract. ‘There
is, the reviewer may add, an exactly similar detached portion of the
optic tract in the bony fishes, which terminates in the nucleus geni-
culatus externus. Cae he
Peripheral Nerve Endings in Amphioxus.'’
The description of the course and distribution of the sensory and
motor nerves confirms in general the results of HEyYMANS and VAN DER
STtRIcHT. The most important part of the paper deals with the periph-
eral endings of the sensory nerves. ‘Two sets of fibers are distin-
guished. The first pass through the homogeneous Hautschicht by
means of special canals and reach a position immediately beneath the
epithelial cells. Here they branch and form a subepithelial plexus
from which ‘‘eine Menge feinster varicéser _Fadchen” pass up and end
between the epithelial cells, The second set of fibers have their cells
' Das periphere Nervensystem des Amphioxus (Branchiostoma lanceola-
tum). Von A. S. DocteL, St. Petersburg. Axat. Heften, Eletitele xevalenn pie
147-213, Pl. XII-XXIX. 1902.
xliv JOURNAL OF COMPARATIVE NEUROLOGY.
of origin in the epithelium. ‘These resemble the sense cells of inverte-
brates. Their outer ends reach to the surface but are not provided with
sense hairs. Their inner ends are continued centrally as fibers which
enter the sensory nerves. ‘These sense cells are found generally in the
epithelium and especially in the oral tentacles where they are grouped
to form the special sense organs which have heretofore been compared
with the taste buds and end buds of typical vertebrates. Nothing is
stated with regard to the central relations of these two sets of fibers.
The author describes certain structures which he regards as spinal
ganglia but their finer structure is not sufficiently well made out to
warrant any conclusion as to their character. J. Bivde
On the Lobus Impar of the Brain of Cyprinoid Fishes.'
In his work entitled, ‘‘Vom Bau des Wirbeltiergehirns,” B. Hat-
LER describes extensive anastomoses between nerve cells in the lobus
impar of the medulla oblongata of the cyprinoid fishes and states
that this structure is an especially favorable object for the demonstra-
tion of such anastomoses. GROTH examined haemalum, carmine and
GoLG! preparations of several carp-like fishes in order to check up the
observations of HALLER, but without finding any evidence of such
anastomoses. ‘There is an extensive but uncritical review of the litera-
ture of these brains and some description from his own preparations of
the anatomical structure of this part of the brain, in the course of
which, however, nothing of morphological importance is brought out.
Ce Je Ve
'GrotH, A. Ueber den Lobus impar der Medulla oblongata bei Cypri-
noiden. Dissertation. Miinchen, 1900.
Volume XIll. APRIL, 1903. Number |.
THE JOURNAL
OF
Comparative Neurology
EDITED BY
C. L. Herrick, ALBUQUERQUE, NEW MEXICco.
ASBOCIATED WITH
OLIVER S. StRoNG, Co_umBia UNIVERSITY,
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GEHUCHTEN, Université de Louvain; C. F. Hopcs, Ph.D., Clark Unsverstty ;
| G. Cari Huser, M.D., University of Michigan; B. ¥. Kincsspury, Ph.D., Cor-
nell University and the New York State Veterinary College; FREDERIC S. LRE,
Ph.D., Columbia University; ADOLF MEYER, M.D., Pathologtcal In-
stitute, New York; A, D. MorriLt, M.S., Hamilton College; G. A.
540.5
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THE JOURNAL OF
Comparative Neurology
A Quarterly Periodical Devoted to the
Comparative Study of the Nervous System in all of its Aspects.
EDITED BY
C. L. Herrick, Magdalena, New Mexico.
ACS SiO'E A TAR De Wolk Ee
OLIVER S. STRONG, Tutor in Comparative Neurology, Columbia University
C. Jupson Herrick, Professor of Zoology, Denison University.
AND WITH THE COLLABORATION OF
LEWELLYs F. BARKER, M.B., Professor of Anatomy, University of Chicago and
Rush Medical College.
FRANK J. CoLe, Demonstrator of Zoology, University College, Liverpool.
Henry H. DonaLpson, Ph.D., Professor of Neurology, University of Chicago.
Prorgssor LUDWIG EDINGER, Frankfurt, a-M.
PROFESSOR A. VAN GEHUCHTEN, Professor of Anatomy, University of Louvain,
Belgium.
C. F. Hopes, Ph.D., Professor of Physiology and Neurology, Clark Untversity.
G. CARL Huser, M.D., /untor Professor of Anatomy and Director of the
Histological Laboratory, University of Michtgan.
B. F. Kincspury, Ph.D., Department of Physiology, Cornell University.
FREDERIC S. LEE, Ph.D., Adjunct Professor of Physiology, Columbia Universtty.
ApDoLF MEYER, M.D., Dérector of the Pathological Institute, New York State
Hospitals.
A. D. MorriLi, M.S., Professor of Biology, Hamilton College.
G. H. ParKeEr, S.D., Assistant Professor of Zoology, Harvard University,
THE JOURNAL OF COMPARATIVE NEUROLOGY issues one volume each year.
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times, should read this Journal.
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instruction, pointing out the practical solution of one of the most difficult problems of
modern times.
Established in 1876, it was the first, and is the only Journal published, presenting
exclusively the scientific side of this subject.
This Journal occupies a field entirely new, and conflicts with no other publication,
and hence has a circle of readers not confined_to any one class.
Subscription Price, only $2.00 per Year.
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oF INEBRIETY, and is taken in all the Asylums and Hospitals in this country, and many
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and philanthropists, from Matne to California, and in the Proyinces of Canada, and all
the European nations.
Address, aie By: Ca eCyl HERS. M. Be
(EDITOR.)
HARTFORD, CONN,
ae
2
DEF ~~
CONTENTS.
CONTRIBUTED ARTICLES.
The Fore-Brain of Macacus. By Wm. Wore Lesem, M. A.
(Columbia University.) With Plates I and II.
Brain-Weights of Animals with Special Reference to the
Weight of the Brain in the Macaque Monkey. By
Epwarp Antuony Sritzka, M.D. (From the Anatomt-
cal Laboratory, Columbia University.)
A Description of Charts Showing the Areas of the Cross-Sec-
tions of the Human Spinal Cord at the Level of Each
Spinal Nerve. By Henry H. Donatpson and Davip
J. Davis. (From the Neurological Laboratory. of the
University of Chicago.) With Chart I.
The Brain of the Archzoceti. By G. Exrtior Suita, M. A.,
M. D., Fellow of St. Johns College, Cambridge ; Profes-
sor of Anatomy, Egyptian Government School of Medt-
cine, Catro. With four figures in the text.
LITERARY NOTICES.
Functional Changes in the Dendrites of Cortical Neurones, i—The
Morphological Position of the Chorda Tympani in Reptiles,
ii—Mendel and Jacobsohn’s Jahresbericht; Fifth Issue,
ii—Nervous System of Myxine, iii—Taste and the Fifth
Nerve, tii—The Phylogeny of the Pallium, iii—Obsessions
and Psychasthenia, xiv—McMurrich’s Embryology, xv—Mo-
tor Nerve Termini in Insects, xvii—The Comparative
Anatomy of the Brains of Lemurs and Other Mammals, xix—
Development of Lepidosiren, xx.
PAGE
41
fin Enumeration of the Medul- a
lated Nerve Fibers in the Dorsal an
Roots of the Spinal Nerves of Ss
Man. | vas
By CHARLES INGBERT,
With Thirty:Two Figures.
(From the Neurological Laboratory of the University of
Chicago.)
[Reprinted from THE JOURNAL OF COMPARATIVE
NEUROLOGY, Vol. XIII, No. 2, 1903.]
THE JOURNAL OF
Comparative Neurology
A Quarterly Periodical Devoted to the
Comparative Study of the Nervous System in all of its Aspects.
EDITED BY
C. L. Herrick, Magdalena, New Mexico.
ASS OC LATED: Wl?
OLIVER S. STRONG, Tutor in Comparative Neurology, Columbia University
C. JupsoN HERRICK, Professor of Zoology, Denison University.
AND WITH THE COLLABORATION OF
LEWELLYS F, BARKER, M.B., Professor of Anatomy, University of Chicago ana
Rush Medical College.
FRANK J. CoLE, Demonstrator of Zoology, University College, Liverpool.
Henry H. Donapson, Ph.D., Professor of Neurology, University of Chicago.
PROFESSOR LUDWIG EDINGER, Frankfurt, a-M.
PROFESSOR A. VAN GEHUCHTEN, Professor of Anatomy, University of Louvarn,
Beletun.
C. F. Hopce, Ph.D., Professor of Phystology and Neurology, Clark University.
G. CARL Huser, M.D., Junior Professor of Anatomy and Director of the
Histological Laboratory, University of Michigan.
R. F. Kinespury, Ph.D., Department of Physiology, Cornell University.
FREDERIC S, LEE, Ph.D., Adjunct Professor of Phystology, Columbia University.
ADOLF MEYER, M.D., Dérector of the Pathological Institute, New York State
Hospitals.
A.D. Morri1tt, M.S., Professor of Biology, Hamilton College.
G. H. PARKER, S.D., Assistant Professor of Zoology, Harvard University.
THE JOURNAL OF COMPARATIVE NEUROLOGY issues one volume each year.
Four numbers usually make a volume, though fascicles may appear at any time.
Back numbers may be obtained at the regular rate of $3.50 per volume. Single
numbers are also sold, the price varying with the contents of the number.
Subscription Price $3,50 per Annum
POST-FREE TO ALL COUNTRIES IN THE POSTAL UNION.
Address business communications to
(*, JUDSON HERRICK, Manager, Denison University, Granville, Ohio, U.S. A.
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Printed at the University Press.
7 -
erie
Sor
ON THE PHYLOGENY AND MORPHOLOGICAL
POsnON;, OF THE TERMINAL : BUDS. OF
PISHES.
By C, JUDSON HERRICK,
(Studies from the Neurological Laboratory of Denison University, No. XVII.)
[Reprinted from THE JOURNAL OF COMPARATIVE NEuROLOGY, Vol. XIII,
No. 2, 1903.]
i
On the Nature of the Pericellular
Network of Nerve Cells.
By SHINKISHI HATAI,
With One Plate.
, (From the Neurological Laboratory of the University of
Chicago.)
{Reprinted from THE JOURNAL OF COMPARATIV
NEvuROLOGY, Vol, XIII, No. 2, 1903.]
ad
Ee a WOOO NUACE ©: .O-F
Comparative Neurology
A Quarterly Periodical Devoted to the
Comparative Study of the Nervous System in all of its Aspects.
EDITED. BY
C. L. Herrick, Magdalena, New Mexico.
AS3 OG DAT ED Wel TH
OLIVER S. STRONG, Tutor in Comparative Neurology, Columbia University
C. Jupson HERRICK, Professor of Zoology, Denison University.
AND WITH THE COLLABORATION OF
LEWELLYS F. BARKER, M.B., Professor of Anatomy, University of Chicago and
Rush Medical College.
FRANK J. CoLe, Demonstrator of Zoology, University College, Liverpool.
Henry H. DonaLpson, Ph.D., Professor of Neurology, University of Chicago.
PROFESSOR LUDWIG EDINGER, Frankfurt, a-M,
PROFESSOR A. VAN GEHUCHTEN, Professor of Anatomy, University of Louvain,
Belgtum.
C. F. Hopce, Ph.D., Professor of Physiology and Neurology, Clark University.
G. CARL Huser, M.D., Junior Professor of Anatemy and Directer of the
Histologwal Laboratory, University of Michigan.
B. F. Kincspury, Ph.D., Department of Physiology, Cornell University.
FREDERIC S. LEE, Ph.D.. Adjunct Professor of Physiology, Columbia University.
ADOLF MEYER, M.D., Director of the Pathological Institute, New York State
Hospitals.
A.D. MorriLu, M.S., Professor of Biology, Hamilton College.
G. H. PARKER, S.D., Assistant Professor of Zoology, Harvard University.
THE JOURNAL OF COMPARATIVE NEUROLOGY issues one volume each year.
Four numbers usually make a volume, though fascicles may appear at any time.
Back numbers may be obtained at the regular rate of $3.50 per volume. Single
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POST-FREE TO ALL COUNTRIES IN THE POSTAL UNION.
Address business communications to
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The Neurokeratin in the Medul-
lary Sheaths of the Peripheral
Nerves of Mammals,
By SHINKISHI HATAI,
With One Plate.
(From the Neurological Laboratory of the University of
Chicago.)
{Reprinted from THE JOURNAL OF COMPARATIVE
NEvUROLOGY, Vol. XIII, No. 2, 1903.]
WH Ber RIN AL. OF
Comparative Neurology -
A Quarterly Periodical Devoted to the
Comparative Study of the Nervous System in all of its Aspects.
EDITED BY
C. L. Herrick, Magdalena, New Mexico.
ALS. 9) OC GAVE EDS WLer Ee
OLIVER S. STRONG, Tutor in Comparative Neurology, Columbia University
C. Jupson HeErRrRIcK, Professor of Zoology, Dentson University.
AND WITH THE COLLABORATION OF
LEWELLYs F, BARKER, M.B., Professor of Anatomy, University of Chicago and
Rush Medical College.
FRANK J. CoLE, Demonstrator of Zoology, University College, Liverpool.
Henry H. DoNALDSON, Ph.D., Professor of Neurology, University of Chicago.
PROFESSOR LUDWIG EDINGER, Frankfurt, a-M,
PROFESSOR A. VAN GEHUCHTEN, Professor of Anatomy, University of Louvain,
Belgium.
C. F. Hones, Ph.D., Professor of Physiology and Neurology, Clark University.
G. CarL Huser, M.D., /untor Professor of Anatomy and Director of the
Fiistological Laboratory, University of Michzgan.
B. F. Kinespury, Ph.D., Department of Physiology, Cornell University.
FREDERIC S. LEE, Ph.D., Adjunct Professor of Physiology, Columbia University.
ADOLF MEYER, M.D., Director of the Pathological Institute, New York State
~ Hospitals.
A.D. Morriti, M.S., Professor of Biology, Hamilton College.
G. H. PARKER, S.D., Assistant Professor of Zoology, Harvard University.
THE JOURNAL OF COMPARATIVE NEUROLOGY issues one volume each year.
Four numbers usually make a volume, though fascicles may appear at any time.
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Volume XiIll. OCTOBER, 1903. Number 3.
PE JOURNAL
OF
Comparative Neurology
EDITED BY
C. L. Herrick, MacpALena, New Mexico.
ASSOCIATED WITH
OLIVER S. StRonG, COLUMBIA UNIVERSITY,
C. Jupson Herrick, DENISON UNIVERSITY.
AND WITH THE COLLABORATION OF
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. J. Cote, Ontversity College, Liverpool; HENRY H, DoNALDSON, Ph.D., University
of Chicago; PRoFEssor Lupwic EDINGER, /rankfurt. a-M.; PROFESSOR A. VAN
GEHUCHTEN, Université de Louvain; C. F. Hopcr, Ph.D., Clark University ;
G, Cart Huser, M.D., University of Michigan; B, F. Kincspury, Ph.D., Cor-
nell University and the New York State Veterinary College; FREDERIC S. LEE,
Ph.D., Columbia University; ADOLF MEYER, M.D., Pathological In-
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instruction. pointing out the practical solution of one of the most difficult problems of
modern times.
' ¥stablished in 1876, it was the first, and is the only Journal published, presenting
exclusively the scientific side of this subject. ‘
This Journal occupies a field entirely new, and conflicts with no other publication,
and hence has a circle of readers not confined to any one class.
Subscription Price, only $2.00 per Year.
This Journal is the organ of the AMERICAN ASSOCIATION FOR THE STUDY AND CURE
oF INEBRIETY, and is taken in all the Asylums and Hospitals in this country, and many
in Eurvpe. It is accepted as authority, and circulated among physicians, lawyers, judges,
and philanthropists, from Mazne to California, and in the Provinces of Canada, and all
the European nations,
Maas toy GROTHERS) My, D,,
(EDITOR.)
HARTFORD, CONN.
CONTENTS,
CONTRIBUTED ARTICLES.
The Neurofibrillar Structures in the Ganglia of the Leech
and Crayfish with Especial Reference to the Neurone
Theory. By C. W. Prentiss. Parker Fellow in
Zoilogy, Harvard University. With Plates V and VI
On the Increase in the Number of Medullated Nerve Fibers
in the Ventral Roots of the Spinal Nerves of the
Growing White Rat. By SuinxisHi Hata. (from
the Neurological Laboratory of the Untversity of Chicago)
On the Medullated Nerve Fibers Crossing the Site of Le-
sions in the Brain of the White Rat. By S. WALTER
Ranson, Jnstructor in Anatomy, Marion-Sims-Beau-
mont Medical School, St. Louis University. (From the
Neurological Laboratory of the University of Chicago.
With Plate VII : k
On the Density of the Cutaneous Innervation in Man. By
CHARLES E, IncBert. (From the Neurological Labor-
atory of the University of Chicago.)
Ona Law Determining the Number of Medullated Nerve
Fibers Innervating the Thigh, Shank and Foot of the
Frog—Rana virescens. By Henry H. DoNALpson.
(From the Neurological Laboratory of the University of
Chicago.) ‘ ‘ é d ‘ : ;
157
177
185,
209
223
Volume XI. - DECEMBER, 1903. Number 4.
Poe JOURNAL
OF
Comparative Neurology
P EDITED BY
C. L. Herrick, Socorro, New Mexico.
, ASSOCIATED WITH
OLIVER S. Srronc, COLUMBIA UNIVERSITY,
C. Jupson Herrick, Denison UNIVERSITY.
AND WITH THE COLLABORATION OF
LEWELLys F. BARKER, M.B., University of Chicago and Rush Medical College; FRANK
J. Core, University of Liverpool; WENRY H. Donarpson, Ph. D., University
of Chicago; PRoFessor Lupwic EDINGER, Frankfurt. a-M,.; PROFESSOR A. VAN
GEHUCHTEN, Université de Louvain; C. F. Hopce, Ph.D., Clark Universtty ;
G. Cart Huser, M.D., University of Michigan; B. ¥. Kincspury, Ph.D., Cor-
nell University and the New York State Veterinary College; FREDERIC S. LEE,
Ph.D., Columbia University; ApotF Mryer, M.D., Pathological In-
stitute, New York; A. D. Morritt, M.S., Hamilton College; G. A.
PARKER, S.D., Harvard University.
Published by the Editors, Denison University, Granville, Ohio.
Issued January, 1904.
JOURNAL OF COMPARATIVE NEUROLOGY AND PSYCHOLOGY.
The enlargement of scope and editorial facilities of Zhe Journal of
Comparative Neurology announced on the Editorial page of this issue
has led to a change in the name of the publication, as indicated in the caption
of this notice, the change to take effect with the first issue for 1904. The
Board of Editors remains as before, save that Dr. RoBERT M. YERKES, of
the Harvard Psychological Laboratory, becomes the responsible editor for the
Department of Animal Rehavior and the staff of Collaborating Editors is con-
siderably enlarged. .
Collaborators
PRroFessor J. Mark Batpwin, Johns Hopkins University.
Prorrssor Lewe.tys F. Barker, The University of Chicago.
Proressor H. HeatH Bawpen, Vassar College.
Dr. A. BETHE, Strassburg.
Proressor G. E. Cocuitt, Pacific University, Oregon.
Dr. F. J. Cote, University of Liverpool.
Proressor H. E. Crampron, Columbia University.
PROFESSOR CHARLES B. DavENPORT, The University of Chicago.
Mr. Wm. Harper Davis, Columbia University.
ProFessoR Henry H. Donatpson, The University of Chicago.
PROFESSOR Lupwic EpINGER, Frankfurt a-M.
Dr. S. I. Franz, Dartmouth College.
PRoFEssOR A. vAN GEHUCHTEN, University of Louvain.
PROFESSOR Ross GRANVILLE Harrison, Johns Hopkins University.
Proressor C. F. Hopce, Clark University.
Dr. S. I. Hotmes, The University of Michigan.
Dr. Ep. B. Horr, Harvard University.
Proressor G. Cart Huser, The University of Michigan.
ProrrssoR Herpert S. JENNINGS, The University of Pennsylvania.
PRoFEssOR J. B. JoHNston, West Virginia University.
Proressor B. F. Kincsspury, Cornell University.
PROFESSOR FREDERIC S. LEE, Columbia University.
PROFEssor JacguEs Loes, The University of California.
Dr. Apotr Meyer, Pathological Institute of the New York State Hospitals.
PRoressoR WesLry Mitts, McGill University.
PrincipaL C. Lroyp Morcan, University College, Bristol.
Prorrssor T. H. Morcan, Bryn Mawr College.
ProressoR A. D. Morritt, Hamilton College.
PROFESSOR Huco MinsTerBerG, Harvard University.
Proressor W. A. NaGet, Berlin.
Proressor G. H. Parker, Harvard University.
Dr. Stewart Paton, Johns Hopkins University.
Dr. Raymond PEARL, The University of Michigan.
Dr. C. W. Prentiss, Western Reserve University.
Proressor C. S. SHERINGTON, University of Liverpool.
PRoressor Epwarp L. THORNDIKE, Columbia University.
Dr. Joun B. Warson, The University of Chicago.
PRoFrEssOR Wm. Morton WHEELER, American Museum of Natural History.
Proressor C. O. WHITMAN, University of Chicago.
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CONTENTS OF THE LAST NUMBER. )
I. Adaptations to Aquatic, Arboreal, Fossorial and Cursorial Habits
in Mammals. II. Arboreal Adaptations. . Louis I. Dublin 5
II. Mutation in Plants 5 : . : Dr. D. T. MacDougal
III. Distribution of the Fresh-Water Fishes of Mexico. : :
: ! j . : “ - : : Dr. S. E. Meek
IV. Examination of Organic Remains in Postglacial Deposits
: ; : : j ‘ ; ; Dr. P. Olsson-Seffer
V. Notes and Literature: Exploration, Hatcher’s Narrative of the
Princeton Patagonia Expedition—Zoology, A Summary of the
Coccide, Another Text-book of Entomology, Two Papers on
Insect Wings—Boftany, A New Flora of the Southeastern United
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CONTENTS.
PS
CONTRIBUTED ARTICLES.
PAGE
The Rate of the Nervous Impulse in the Ventral Nerve-Cord of
Certain Worms. By O. P. Jenkins and A. J. CARLSON.
(From the Hopkins’ Seaside Laboratory and the Phystological
Laboratory of Leland Stanford, Jr., University.) ~With
fourteen figures. oh Wr Ong 1 4 UE ae ae
Notes on the Technique of Weigert's Method for Staining
Medullated Nerve Fibers. By O. S. Strone, Coluwnbia
Oniversity, New York’... 0. 3-23 3s
The Doctrine of Nerve Components and Some of Its Applica- —
fions,. By C. Jupson. Herrick. : >.) ).ee3 ae
Columella Auris and Nervus Facialis in the Urodela. By B. |
Py KRINGSBURY.*
Editorial Announcement. . : : : : : ‘ : S55
LITERARY NOTICES.
The Relations of Biology and Psychology, xxix—The Psychology of
Action, xxxiii—The Fore-Brain of the Bird, xxxix—The Optic
Chiasma and the Post-Optic Commissure, xlii—Peripheral
Nerve Endings in Amphioxus, xliii—On the Lobus Impar of
the Brain of Cyprinoid Fishes, xliy.
——
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