Minute structure of the central nervous system of certain reptiles and batrachians of America

i^,;.*^

-f-w.i>

M

;v*s

iie-

J!!^

t^*is«j

;.«&:

l^Sl

'' \?*N» :

■l^^v^t^

^-^

PRESENTED BY

DR. JOHN J. MASON, NEWPORT, R. I.
PLEASE ACKNOWLEDGE.

o

MINUTE STRUCTURE

OF THE

CENTRAL NERVOUS SYSTEM

OF CERTAIN

REPTILES AN DBATRACHIANS

OF

AMERICA.

ILLUSTRATED BY PERMANENT PHOTO-MICROGRAPHS.

-' BY

JOHN J. MASON. M. D.

SERIES A.

J?

.vuthor's edition, one hundred.

Newport: 1879-1882.

UIUVERBTnf.

'I'O

PROF. SPENCER F. BAIRD,

IN GRATEFUL ACKNOWLEDGMENT OF HIS FRIENDLY AID AND COUNSEL,

THIS WORK IS RESPECTFULLY INSCRIBED.

LIST OF ANIMALS STUDIED.

REPTILIA.

SAURIA.

ALLIGATOR MISSISSIPIENSIS,
HELODERMA SUSPECTUM,
ANOLIUS CAROLINENSIS,
PHRYNOSOMA CORNUTUM,
SCINCUS ERYTHROCEPHALUS,

OPHIDIA.

SPILOTES EREBENNUS,
NERODIA FASCIATA,
SCOTOPHIS QUADRIVITTATUS,
TOXICOPHIS PISCIVORUS,
CROTALUS ADAMANTEUS,

CHELONIA.

TESTUDO POLYPHEMUS,
EMYS FLORIDANA,
CISTUDA CAROLINA,
CHELYDRA SERPENTINA,

ALLIGATOR.

GILA MONSTER.

CHAMELEON.

HORNED TOAD.

RED-HEADED LIZARD.

GOPHER SNAKE.

WATER SNAKE.

CHICKEN SNAKE.

MOCCASIN.

RATTLE SNAKE.

GOPHER TURTLE.

RIVER TERRAPIN.

BOX TURTLE.

SNAPPING TURTLE.

RANA PIPIENS,
RANA HALECINA,

BATRACHIA.
ANURA.

URODELA.

MENOPOMA ALLEGHENIENSE,
DIEMYCTYLUS TOROSUS,

BULL FROG.
SPOTTED FROG.

HELLBENDER.
SALAMANDER.

TRACHYSTOMATA.

SIREN LACERTINA,

SIREN.

CONTENTS.

PAGE

Title page, dedication, and list of animals studied.

INTRODUCTION. METHODS EMPLOYED 1-5

SPINAL CORD 6

MEDULLA OBLONGATA 13

CEREBELLUM 16

OPTIC LOBES 18

CEREBRAL AND OLFACTORY LOBES 20-21

APPENDIX. NUCLEI IN NERVE CELLS 22

LITERATURE OF THE SUBJECT. List of publications.

LIST OF PLATES WITH MAGNIFYING POWERS, &c.

PLATES I. CXIII. With numbers of negatives and objecti\'es used.

INTRODUCTION.

This work was begun about three years ago, under the conviction that
much remained to be accompUshed in illustrating, by photography, the
structure of the central nervous system. After experimenting with va-
rious methods, I found that satisfactory prints could be made, in ink,
directly upon plate paper, and that these impressions were as perfect in
tine detail as any of those obtained by the silver process of printing.

The plates, which form the larger part of the book, are as durable
as steel engravings, and have all been printed by the artotype process,
from my own negatives of sections selected from over rive thousand
preparations made by my own hands. This will in part account for the
time spent, the difficulty of making and mounting sections, suitable for
good photography, being well known.

Last ^ear, I distributed several incomplete sets of mounted and
varnished prints from some of the same negatives ; and the writers of the
very flattering acknowledgments, which I have received, are in no small
ineasure responsible for the present publication.

My thanks are especially due to Dr. J. J. Woodward, for indispen-
sable assistance at the \ery commencement of my work, in practically
explaining his method and theorj' of illumination of the object, and for
advice and encouragement on several occasions.

Without the valuable help of Prof. S. F. Baird, and the Smith-
sonian Institution, many of the most important illustrations could not
have appeared for several years.

2 INTRODUCTION.

I am also much indebted to the Messrs. WilHams and Dubois, for
their skilful and patient labor in the artot}'pe printing, at Newport.
There has been no i^etouching of the negatives, although, in sonre cases,
a tinted disk has been printed over the plate, by a second impression,
as in I. & II.

Attempts to print in carmine ink, so as to retain the actual color of
the stained sections, have not thus far proved successful.

While a photograph can not often show all that can be discovered
by more direct microscopic observation, with a judicious working of the
fine adjustment; high authorit}- has stated, and perhaps correctly, that
a good photograph, with a low power — say from 3 to 1-2 inch, — is a
better means of illustrating the anatomical structure of the nenous tis-
sues, than hand drawing.

Some of the plates, — LXXXI. & XCIV. — with high powers, leave
much to be desired both in distinctness and tone ; and in general it may
be affirmed that the same defect, as regards distinctness, always exists,
and for obvious reasons, in photographs of sections with powers much
above 1-2 inch. In fact, it now appears to be established that iinmer-
sion objectives can never be employed, for photographing section prep-
arations, with the success that has attended their use for blood-corpus-
cles, diatoms and similar specimens.

To give to the student enlarged and exact representations of hard-
ened preparations, showing comparative form and dimensions, with as
much of the structure as possible, has been the chief aim constantly in
view ; and the author will be more than repaid for his labor, if any one
of the illustrations, here presented to science, shall prove a help in under-
standing the structure of the nen-ous system, or be regarded as an ad-
vance in the art of photo-micrography.

The minute structure of the central nervous system, of many reptiles

INTRODUCTION. 3

and batrachians, has been already extensively studied. In the list of pub-
lications given farther on, it will be noticed that many of the writers have
taken for study one animal at a time, and it will be found also that
the works of most of them treat of their subjects very exhaustively.

In the present work, no one animal is made a special object of re-
search ; but anatomical facts, taken from the different types, are brought
together in order to facilitate comparison. The presentation of some of
the most striking points of difference and resemblance, with a brief no-
tice of a few appearances and structures, which it has been my good
fortune to discover, form the greater part of the text.

Others may here find for themselves useful data which have es-
caped my notice ; for it will be evident that the illustrations, being ana-
tomically correct, can, unlike many hand drawings, be studied as if they
were microscopic specimens.

Following the example of nearlj- all other writers on the nenous
system of these animals, the relations and positions of parts are indica-
ted b}' terms which refer to the usual posture of a reptile with its abdom-
inal surface towards the earth. The "posterior roots," for instance,
of human anatomy, are here named : superior or upper roots, etc.

Without wishing to discuss toponomy, I will here state that the
choice of nomenclature has been with me determined entirely by person-
al preference, and implies no want of appreciation of the merits of the
excellent system* recently proposed by Prof. B. G. Wilder.

METHODS EMPLOYED.

With the exception of the sections represented by Plates I. — IV.,

* "Science," II, Nos. 38, 122-126, Nos. 39, 133, 13S. Also "The Brain of the
Cat." Am. Philosoph. See, 1881.

4 METHODS EMPLOYED.

XXXIII. , XXXVI., XLV., XLVL, XLVIII., LIII. & LVIIL,

which were taken from specimens hardened first in chromic acid, the
preparations used for the illustrations have all been obtained by the same
process.

Both the brain and spinal cord were entirely separated from the
body, and, with their membranes, placed in iodine tinted alcohol until
they had acquired a slight degree of consistency — from six to twelve
hours. They were then transferred to a — 3-100 — solution of bichrom-
ate of potash, with a small piece of camphor, in a tightly corked, wide-
mouthed bottle, and allowed to remain until ready for cutting, renewing
the solution every two weeks.

The time required for the hardening process varies considerably in
different animals, and this variation is more dependent upon the class of
the animal than upon the relative dimensions of the specimens.

For example : on the same day, I placed the brain of a large rattle-
snake with that of a small salamander in the same bottle, and at the
end of six weeks, the former was ready for section, while the latter was
not sufficiently hard until a month afterwards. By thus employing the
same reagents in all cases, I have been able to note constant differen-
ces in the action of both the hardening and the coloring agent, carmine.

Perhaps the most striking illustration of this is furnished by the
nervous centres of tailed batrachians, which, while they stain verj- read-
ily, invariably require about a third more time to harden than spec-
imens from the other orders. Specimens from ophidians stain less sat-
isfactorily than those from any other of the classes which I have studied,
while with the spinal cords of alligators, turtles and frogs, failure to obtain
good results, in this particular, is ver}^ rare.

In all cases the sections have been stained after cutting, injur)' from
excessive handling being wholly avoided by the use of siphon tubes to

METHODS EMPLOYED. ^

remove the alcohol and washings. For producing transparenc}-, oil of
cloves has been used, and the mounting has been done under thin, clear
covers, in a solution of Canada balsam in chloroform.

All the negatives have been made on glass thoroughly cleaned and
lightly coated with a solution of wax and benzole, so that the collodion
film, previously made adherent to thin sheets of gelatine, could be safe-
ly removed from the plate. The flexible negatives, thus obtained, are
well adapted to the artotype process, and, as they can be indefinitely
preserved between the leaves of an ordinary scrap-book, are very desir-
able for a series of illustrations. In making the orisinal negatives on
glass, the "wet collodion process," with the sulphate of iron developer,
has been exclusively employed.

The prints correspond exactly with the negatives both in outline
and detail. No distortion occurs as in silver printing, in which process
the paper is subjected to prolonged washing.

In many of the photographs the gray substance appears lighter in
shade than the white substance. This appearance is due to a greater
degree of transparency of the gray substance, in these sections, resulting
from the action of the oil of cloves, followed b}- an increased action of
the transmitted light on the sensitive collodion film of the negative, and
hence b}- a tliinner deposit of ink over corresponding parts of the positive
plates from which the artotypes are printed.

THE SPINAL CORD.

When examined in transverse sections, the spinal cord of a reptile or
batrachian, like that of the higher vertebrates, is found to be composed
of two substances, the v^^hite and the gray, and, in most cases, the natu-
ral division into six columns is to be obsen-ed in the white substance.

The superior (posterior) median fissure does not exist as such, its
position being marked, much as in man, by a membrane which extends
vertically downwards from the pia mater, dividing into halves the por-
tion of the white substance included between the superior roots of the
spinal nerves.

Gerlach states that in man : "Both portions of the pia mater extend
to the bottom of the anterior fissure, that is to say, as far inward as the
anterior white commissure, while only the adherent layer of the pia ma-
ter sinks directly down into the posterior fissure to the gray commissure.
This posterior septum unites the posterior columns so closely that a
posterior fissure can not well be said to exist in the strict meaning of the
word."

Figures 240 & 241, in his contribution to Strieker's manual of his-
tology", show, after removal of the pia, a well marked posterior fissure.
As this never appears in reptiles, it is fair to conclude that the union of
these columns is closer than in man. Plates I. II. & III. illustrate the
six divisions into columns above referred to.

In saurians, between the inferior white and gra}- commissures, two
longitudinal bundles of white nene fibres extend from the posterior lum-
bar region well into the medulla oblongata, where they form on each

y CENTRAL NERVOUS SYSTEM.

side what Stieda names, in turtles, the "central longitudinal bundle of
the medulla oblongata.'"* The comparative importance of this bundle
in different regions of the cord, is shown in Plates XI. XII. & XIII.
It forms a conspicuous part of sections from the alligator, iguana, helo-
derma, skink and anolis.

Plates I. — IV. & XXIV. are referred to as suggesting that in rep-
tiles with bodies shielded b}- bony plates or thick scales, the fibres of the
superior columns, compared with those of the inferior columns, are rel-
atively smaller than in naked reptiles ; and also as illustrating the fact,
noted by Gerlach for the human spinal cord, that the fibres, which form
the infero-lateral columns, are, as a whole, larger in the cenical than
in the lumbar region.

The depressions in the outline of the lateral columns seen in Plates
I. & V. for example, correspond with the position of the lateral ligament,
recently described by me, the structure of which in ophidians, is shown
in Plates XIV. & XV. See Journal of Nenous and Mental Disease,
Vol., VIII, No. 3, July, 1881.

The mode of exit and the course of the inferior root-filaments are
well shown in Plates III. & IV. and their relation to the large ner\-e
cells in the inferior horns of gray matter, is made veiy apparent in Plates
XVIII. XXXI. & XXXIII.

Plate XIV. II shows the characteristic mode of exit of the superior
roots in ophidians, and Plates XXVI. & XXXVI. show the arrange-
ment of the same parts in the brachialf region of the frog.

The gray substance of the spinal cord is composed of fibres, ner\-e
cells, connective tissue and blood vessels. Its position is central to the

* Ueber den Bau des Centralen Nenensystems der Schildkiote. p. 53.
t The terms, 'brachial' and 'crural' were used by Wyman to designate the en-
largements of the frog's spinal cord.

SPINAL CORD. 8

white substance, and, as in man, its contour resembles that of the capi-
tal letter H. In ophidians and tailed batrachians, this resemblance is
less close on account of the fusion of the superior horns in the former,
and the interposition of the substantia reticularis, between the two halves
of gray matter, in the latter.

It is remarkable that Reissner, who first described the substantia
reticularis in the brachial region, failed to find it in other parts of the
spinal cord. Stieda* speaks of it as existing in the brachial, dorsal and
crural regions, and as being broadest in the crural enlargement. Plates
XXXIV. & XXXV. show that, while in the latter region of the cord it
surrounds the central canal, its area is no larger than in the brachial re-
gion. Possibly this is a point of difference between the European and
American species.

The central canal, in cross sections, appears in the form of a dis-
tinctly limited opening, surrounded by conical, ciliated epithelium. The
form of these epithelial cells is best seen on the linings of the cavities of
the brain, including that of the fourth ventricle. See Plates LXXX.
LXXXI.XCIII. &XCIV. In the frog's spinal cord, (Plate XXXII.)
these cells send out processes, which are seen to be continuous with the
net-work of the substantia reticularis.

The structure of this net-work, as well as its outline and position in
regard to the central canal, at different planes, can be studied in Plates
XXVI. — XXXV. It is an arrangement of fibres peculiar to the spinal
cord of batrachians, and affords probably the best example of what is
almost universally regarded as connective tissue.

In regard to the comparative amounts of white and gra}' matter in
various regions of the spinal cord, it may be safely affirmed that no ex-
planation has yet been given, which accounts for all the variations to be

* "Studien iiber das Centiale Nervensystems der Wirbelthiere," 1870, p. 6.

9 CENTRAL NERVOUS SYSTEM.

observed in different animals. The following considerations may con-
tribute something towards a clearer understanding of the true relation
which here exists between mass and function.

A careful examination of Plates XXVI. & XXVII. will convince all
that, in the frog, the disparity between the thickness of the brachial and
that of the crural enlargements, is due, almost entirely, to a greater
amount of white substance in the former region.

From the plates of Gerlach, made with photographic accuracy, it
appears that in man, a non-caudate vertebrate, the principal quantitative
variation relates to the gray matter, which, in cross sections, is much
more abundant in the lumbar than in the cer\'ical enlargement ; while
the white matter seems to be somewhat greater in amount in the latter
enlargement, although relatively less than in the frog.

In the frog, the length of the lumbar stands to that of the cenncal
enlargement, in the ratio of lo — 6. In man, they are more nearh'
equal in length. The gray matter of the frog's lumbar enlargement,
therefore, is more abundant than that of its cer\'ical enlargement, and
corresponds, in this respect, with the spinal cord of man ; making up in
length for lack of thickness.

In saurians with long and powerful tails, as the alligator and iguana,
the amounts of gray and white substances are nearly the same for both
enlargements ; while in those with short and feeble tails, as the horned
toad, heloderma and skink, the cervical enlargement, which is of near-
ly the same length as the lumbar enlargement, predominates in thick
ness, and in the actual amount of both white and gray substances.

In chelonians, the variations are still more striking and instnjctive.
Plates XVI. — XXV. give, from five different species, abundant illustra-
tration of the well known fact, that the gray substance of the dorsal re-
gion is much more reduced in quantity, than it is in any other verte-

SPINAL CORD. lO

brates. It contains no large cells in its inferior horns. An apparent
exception is to be noticed in Plate XX. iii, — box turtle — large cells be-
ing shown in a section which was made just in front of the lumbar en-
largement. Sections of the middle dorsal region, from the same speci-
men, were found to be free from large cells.

Tliickness of the Spinal Cord, in its AnterioT-
and Posterior Regions, Compared.

Alligator. Tail powerful. Posterior equals Anterior.

Iguana. " '•'• "• exceeds* "

Phrj'nosoma. " rudimentary. Anterior " Posterior.

Anolius. Tail long but weak and fragile. " " "

Skink. " large " " " " " " "

Heloderma. " " " " " " "

Turtle. Tail rudimentar}-. " much exceeds "

Chelydra.f " well developed. " exceeds "

Tailed Batrachians. " " " " equals "

Tailless " " much exceeds "

Plate XVIII. — gopher turtle — represents the inferior horn of one
side from a cross section through the middle of the cervical enlargement.
The group of large cells, multipolar and bipolar, in which the nuclei

* This apparent anomaly loses its force, as such, when one considers that the
difference in thickness, between the enlargements, is small, and depends upon an
increase of gray substance, corresponding with a difference in development between
the two pairs of extremities greater than in the alligator.

t In the snapping turtle, the tail, although it is powerful, occupies in respect to
its development, a position intermediate between that of the common land turtle and
the alligator, thus corresponding with the lumbar enlargement which is. relatively
thicker than in the ordinary turtle. Compare Plates XXII. & XXIII. with XIX. i, in.

II CENTRAL NERVOUS SYSTEM.

and nucleoli are plainly visible, may be taken as a type of what is al-
ways found in the enlargements of the spinal cord of reptiles and ba-
trachians.

It is uncertain whether the striation of the cell-body, Plate CIX.,
denotes true fibrillar structure, or is due to the action of reagents.

Besides the group of large cells, there are many small ones scattered
through the gray substance. These are more abundant in batrachians
than in reptiles proper, and their nuclei are often difficult to distinguish
from those of the connective tissue. The latter are verj' prominent ob-
jects in sections from tailed batrachians, appearing conspicuously in both
the white and gray substances.

In Plate V. i-iii — alligator 3 mos. old — these nuclei are shown as
small, dark objects especially abundant in the white substance. See al-
so Plate XCIX. in which the difference between the small ner\-e cells
and the elements of connective tissue is quite apparent.

Ner\-e cells of middle size, with nuclei of corresponding dimensions,
are also found in various parts of the gray substance, but never as a dis-
tinctly limited group, with the exception of the dorsal region of the frog,
where thej- appear as represented in Plates XXIX. & XXX. just above
the level of the central canal, one group on each side of the substantia
reticularis. These cells were described by me in the New York Medi-
cal Journal for December, 1879, with a hint as to their possible homol-
ogy to the columns of Clarke.

The fibres in the gray substance, exclusive of those which belong
to the connective tissue, are very abundant, and especially so in the al-
ligator and turtle. Plates I. & II. from chromic acid preparations give
an idea of the structure, in this respect, of the inferior horns ; the bun-
dles running in many directions, and being as large as the fibres of the
inferior roots. Plates XVI. & XVIII. from preparations hardened in

-A-

SPINAL CORD. 12

the bichromate, make it veiy evident that some of these fibres are close-
1\- related to the prolongations of the nerve cells, and Plate XXXIII.
from a chromic acid preparation, demonstrates the fact, that many of the
axis-cylinders of the inferior roots, in the frog, can be followed well into
the gra}' substance and are lost among the large cells.

Contraiy to the opinions of both Reissner and Stieda, I know of no
other animal in which so many of these axis-cylinders can thus be traced,
in sections of chromic acid preparations.

Areas of Gray Matter in Cross Sections, from the

Tivo Enlargements, Compared.

Saurians Cenical equals Lumbar.

Testudo Polyphemus. Ant. more developed

than Post. Extremities. " exceeds "

Testudo Viridis. Ant. much more developed

than Post. Extremities. " much exceeds "

Emys Floridana. \ _,

Post, more developed
" Terrapm. ;- . . " equals

^ . \ than Ant. extremities.
Cistud. Carolina. )

Chelydra S. Extremities about equal. Lumbar slightly exceeds Cervical.

Rana. . . . Post, more developed

than Ant. extremities. Cei^ical " " Lumbar.

In all chelonians, the cervical is much longer than the lumbar en-
largement. As before stated, in the frog, the lumbar enlargement is
the longer; while in saurians, the}- are more nearly equal in length.

The author does not intend, by the facts here tabulated, to be un-
derstood as advocating an-\- theory, and the same ma}- be said of the ta-
ble on page lo.

13 CENTRAL NERVOUS SYSTEM.

THE MEDULLA OBLONGATA.

The transition from the spinal cord to the medulla oblongata is veiy
gradual. Plate XLV. represents the first change which is noticed in the
arrangement of the central parts. The central canal — in saurians — be-
gins to occupy a lower plane in cross sections, and seeins to have earned
with it the inferior cominissure ; and a centimeter behind the fourth ven-
tricle— alligator 3 feet long — the canal remains at about the same level,
but soon is found in a higher position, and opens into the ventricle as
shown in Plate LIL

Here, in the alligator, the raphe first appears, and continues in the
series as far foi-ward as the part which, coiTesponds with the pars com-
missuralis of the frog, — Reissner and Stieda — and with the pons Varolii
of man. Imbedded in the meshes of the raphe, nene cells begin to ap-
pear near the lower border of the medulla. These cells extend forward
increasing gradually in size, until a plane is reached just behind the au-
ditor}- ners'es, where both the cells and their nuclei have dimensions
greater than those of any other cells of the nenous system.

The larger cells are situated in a horizontal plane higher than that
occupied by the smaller cells, and were first described b}' me, a few
years ago, as being, so far as their large size and position in the raphe
are concerned, characteristic of the alligator. See Plates XLVIIL &
Cin. In the alligator, these cells are never found in planes anterior to
the auditor}' nerxes. Stieda* found a similar group of cells, in the land
turtle of Europe, and named it : "nucleus basilaris." The cells are not
* "Ueber den Bau des Centralen NeiTcnsystems." Schildkrote. Loc. cit. p. 51.

MEDULLA OBLONGATA. I 4

described as lying within the raphe, which is httle developed in turtles,
and forms apart of what he calls: "the inferior median extension of
gray substance."

Plate LVII. shows, roughly, the shape of the medulla oblongata of
the gopher turtle. The inferior portion of the septum corresponds with
the median extension of "gra}'" substance. It is easy to find here the
"nucleus basilaris" and follow it as far foi-ward as the fifth pair of nerves
where the cells are the largest.

Cells somewhat similar to those in the raphe of the alligator, I have
found in that of skinks, anolis, heloderma and the iguana, in all saurians,
the raphe being well developed. The situation and form of a group in
serpents, closely answering to the "nucleus basilaris" are shown in
Plates LIV. & LV.

In fact, Plate LIV. is a representation of three groups on either
side of the raphe in a species of black snake, which are probably the ho-
mologues of those observed by Stieda in turtles and which he called :
"nucleus basilaris," "nucleus centralis" and "nucleus lateralis."

The inferior group of the nucleus centralis, in the turtle, is well
shown in Plate LVI. in, and is seen to differ from the superior group, in
the constant lateral direction of its cell processes. I have found both of
these divisions of the nucleus centralis — a name first given b}- Reissner
to a similarly situated group in the frog — in the alligator, heloderma
and iguana. Under Plate LI., I have ventured to suggest the possible
relation of this centre to the vagus. It is perhaps more probable, that
the cell column, which extends from the anterior bundles of the spinal
accessor}', as far as the anterior bundles of the vagus, contains all the
cells of origin of both the vagus and hypoglossal nerves ; the cells of the
spinal accessoi-y lying behind. See Plate XLVII.

I have been unable to trace the hypoglossal roots to an}- distinct

15 CENTRAL NERVOUS SYSTEM.

group of cells, either in reptiles or batrachians. Plate LI. seems to in-
dicate the larger cells as the vagus centre, although some of the fibres
of the hypoglossus can be followed as far as the same group.

The cells of origin of the abducens nerve, have been demonstra-
ted, in all the reptiles referred to in this work. Plate LVII. shows
their position with reference to the floor of the ventricle and to the fibres
of the nerve.

An upper and a lower group of cells, both of which appear in sec-
tions, to be related to the acoustic nerve, can be clearly distinguished in
most cases ; the upper group consisting of small, and the lower group
of large cells. I have verj^ seldom found both divisions in chelonia,
while the group of large cells is readily shown, in all the classes, except
that of batrachians. The large-cell group is especially conspicuous in
ophidians ; in the skinks and iguanidae among saurians, and in all turtles.
In the alligator, this group is not numerous and the cells are relatively
smaller.

The small-cell group is well represented, as seen in cross section,
by Plates XLIX. & CIV. and in longitudinal section, by Plate LIII.
These elements of the "eminentia acustica" or "tuber ner\-i acustici,"*
b)' their position and great number, are peculiar to the alligator.

Deitersf in support of, and perhaps biased by his theory- about
nene cells, states : "So far as the large nene cells at the origin of the acus-
ticus are concerned, they have nothing to do with this nerve, but belong
to the crura cerebelli ad medullam oblongatam, which is partly surround-
ed and partly traversed by the acusticus." In view of this positive as-

* Names given to a prominence developed on the lateral borders of the fpurth
ventricle, at the exit of the acoustic neives. Rabl-Rilckhard, loc. cit. p. 349.

t Untersuchungen uber Gehirn u. Riickenmarks des Menschen u. Saugethiere.
1S65 p. 85.

MEDULLA OBLONGATA CEREBELLUM. I 6

sertion, and in the absence of direct proof to the contraiy, it would be
unwise to claim that the division, above given, of the centre for the acous-
tic ncr\e, is correct, in spite of equalty positive assertion, and appearan-
ces, some of which, especially in reptiles, are favorable to the more mod-
ern view and opposed to that of Deiters.

In the frog, cross sections of the pars commissuralis, including the
cerebellum, contain a group of cells, (shown in Plate LVIII.) which
are seen to be in close relation to some of the lower fibres of the trigem-
inus. This bundle of fibres may justly be regarded as the motor portion
of the trigeminus, from its evident relation to cells having about the
same position as the motor-trigeminal cells of reptiles. In saurians,
chelonians and ophidians, this centre of origin is more easy of demon-
stration than in the frog.

Plate L. gives a good representation of the position of this ganglion
in the alligator, and its relation to the fibres of the motor-trigeminal root ;
the latter extending obliquely downwards from the cells towards the
border of the white substance. In Plate CI I. the same group is enlarged
300 diameters. Plate LVI. iv shows the same parts in the turtle.

THE CEREBELLUM.

Plates LXIII. — LXIX. all from longitudinal vertical sections, facili-
tate a comparison of the different shapes of the cerebellum and its posi-
tions in relation to the optic lobes, in reptiles and batrachians.

Beginning with the alligator, Plate LXIII. the vertical por-
tion on the right of the photograph, is next the optic lobes the

organ is seen to be folded backwards upon itself, increasing its volume

1 7 CENTRAL NERVOUS SYSTEM.

without altering its essential structure, which is the same as in other rep-
tiles. By thus cun-ing posteriorly it resembles the cerebellum of turtles
and serpents. Plates LXVII. & LXVI. In the green turtle, and other
marine species, also in river species, the organ forms a coinplete cover-
ing for the fourth ventricle, extending backwards over the ventricle twice
as far as in the alligator.

In the frog, as shown by Plate LXVIII. its position is nearly verti-
cal, and so far as its form is concerned, independent of the optic lobes ;
while in tailed batrachians, — Plate LXIX. — the optic lobes seem to en-
croach upon its substance.

Plates LXIV. & LXV. represent the direction in the cunature of
the cerebellum in all the saurians, which I have studied, with the excep-
tion of the alligator. See the admirable drawings of Rabl-Riickhard.
In heloderma, the organ curves forwards ; but it is not as closely applied
to the optic lobes as in other lizards. Whatever may be its shape, the
gray layer always lies towards the fourth ventricle, and the white layer
towards the optic lobes.

Besides the nen'e cells referred to on page i6 as belonging to the
motor root of the trigeminus, and the small and middle-sized cells which
are scattered though the pars commissuralis, — underlying extension of
the medulla oblongata, — there are other cells, of middle size, always to
be observed in sections of the cerebellum itself. These characteristic cells
are quite plainly shown, in some of the photographs, with most of the
layers given b}' Stieda,* viz. i, Epithelium. 2, Nen'e Fibres. 3, Gran-
ular substance with small nuclei. 4, Ner\e Cells. 5, Superficial white
layer and pia mater.

Plate LVIII. shows the cerebellum of the frog united to the pars
commissuralis of Reissner.

* Schildkrote, loc. cit., p. 58.

CEREBELLUM OPTIC LOBES. 1 8

Just in front of the cerebellum is the valvula cerebelli, containing
the decussating fibres of the fourth pair of cranial nerves. These nei"ves
have their origin in a group of cells beautifully illustrated by Stieda, as
they are found in the turtle.

THE OPTIC LOBES.

In Plates LXX. — LXXXV. I have represented not onlj- the outline of
these important parts of the encephalon, but have also by the use of high-
er powers, endeavored to give a more satisfactory idea of their minute
sti^ucture. The arrangement of the cells of the cortex or roof "decke"
into separate zones, which is always to be obsei'ved, in saurians, che-
lonians, and batrachians, does not appear in sections from ophidians.
Plates LXXIIL— LXXVI.

Although these plates were made from three different species, and
b}- the inethod generall}' employed throughout, it is possible that this
absence of linear arrangement of the cells is due to faults in preparation.
It is more probable however, that it signifies a peculiar structure, and
chiefly from the fact that sections of the cerebral lobes from the same in-
dividuals, and by the same method, show the usual arrangement of nu-
clei. Compare Plates LXXIII. & LXXIV. with LXXXIX.

In the cerebellum of the saine class of reptiles, the ner\'e cells are
seen, both in transverse and longitudinal vertical sections, to be more
widely scattered through the white la)-er than the}' are in the other class-
es, where they are limited to the zone between the white and gray layers.

The "roof" over the ventricular cavity of the optic lobes, in the

19 CENTRAL NERVOUS SYSTEM.

turtle, is remarkable for the development of a beautiful group of cells,
situated in the median line, and first described by Stieda.*

Plate LXXVIII. shows the same group in the Florida emys. It
is also present, but as a less striking feature, in saurians and ophidians.

On either side of this central group, extending laterally and down-
wards around the margin of the ventricle, and in some cases parallel to
its epithelial lining, are successive layers of small ner\'e cells and nuclei.

These cell strata are regarded as the origins of the fibres of the optic
nerves. In chelonians, some saurians and tailed batrachians, scattered
at unequal intervals among the cells, which form the strata, larger cells,
isolated or in scant)' groups, are frequentl}' found, as in Plate LXXXIV.
In the region beneath the optic lobes, called by Reissner the pars pe-
duncularis, are found the cells of origin and fibres of the oculomotorius.
Plates LXXVII. CX. & CXIII. The origin of the oculomotorius is
not demonstrable in tailed batrachians.

Stieda compares the mid-brain of the axolotl with a tvibe, the open-
ing of which is spindle-shaped in cross sections, and expresses the opin-
ion that there is in realit}- but one lobus opticus, the common division
into pairs being based upon external appearances alone. f

This view may be nearer the truth than the prevailing one, but can
hardly be reconciled with such appearances as those furnished by Plates
LXXI. & LXXII. In the siren and axolotl, it may be well to speak
of the lobus opticus ; but the plates referred to show, in the horned toad
and anolis, two distinct lobes, and what is more conclusive, in the plate
from the horned toad, commissural fibres are shown uniting these lobes.
This section, although cut in a vertical plane, is seen to include the optic
chiasm, and the cause is seen in Plate LXV.

* Loc. cit., p. 63.

t Axolotl, loc. cit., pp. 21-22.

OPTIC THALAMI CEREBRAL LOBES. 20

In front of the optic lobes, in batrachians and those reptiles in which
the cerebral lobes extend but little posteriori}', transverse sections show-
simply two sj-mmetrical masses, joined below and diverging above, one
on each side of the V shaped third ventricle. These are the optic thai-
ami. Underneath are the tuber cinereum with its ventricle, and the hy-
poph3'sis cerebri.

THE CEREBRAL LOBES.

Plate XCIL shows a section made through the anterior portion of the
third ventricle so as to include the lateral ventricles of the cerebrum, with
the choroid plexus in the median fissure. This fissure, in another plane,
communicates with the lateral ventricles, forming the ventriculus com-
munis of Stieda.

Plate XCL is from a section made through the middle of both cere-
bral lobes, and represents the protuberances on their inner walls, the
lower pair being the corpora striata. The caudate cells of one of the
upper protuberances are demonstrated in Plates XCIIL & XCIV.*

Plates LXXXVL— XCVIIL furnish evidence of the similarity in
the general aiTangement of paits in the cerebral lobes of these animals.
In those from saurians and ophidians, the development of the corpus stri-
atum is seen to exceed greatly that of the same organ in batrachians.

Plate LXXXVL from heloderma, shows much the same configura-
tion that is found in the alligator, although the corpus striatum is rel-

* These protuberances are erroneously named : coi-pora striata, under Plates XCII.
XCIII. & XCIV.

21 CENTRAL NERVOUS SYSTEM.

atively of greater volume, and the upper and middle ventricular walls
thinner, in the latter animal.

In the box turtle, — Plate XC. — the corpus striatum is seen to be a-
bout as large, proportionally, as in saurians. This plate also shows the
manner in which the lateral ventricles communicate with the third ven-
tricle. The upper and middle walls are thin, and their zone of cells
lies nearer the surface of the ventricles than in saurians and ophidians,
in this respect resembling batrachians.

Plate LXXXIX. from a transverse section — gopher snake — made
through the posterior part of the optic chiasm, shows the third ventricle
and optic tracts with the cerebral lobe of one side, and its large ventric-
ular protuberance ; downward extension of the same, and tendency of
the upper wall towards symmetry of curvature.

The essential structure of the choroid plexus, and its relation to the
walls of the ventricles are seen in Plate XCVIII.

THE OLFACTORY LOBES.

The olfactory lobes of the frog, as seen in cross section, may be taken
as a fair type of these organs in all the species. The olfactorj' neives
are underneath the lobes, in this batrachian, — Plate XCV. — while in
the tailed varieties, they are on each side.

A LATER series will include several species not mentioned in the present
work, and an effort will be made to illustrate the minute anatomy of
certain parts of the central nervous system, such as the optic thalami
and hj-pophysis cerebri, which, from want of preparations suitable for
photography, are now omitted.

APPENDIX.

COMPARISON OF THE AVERAGE SIZE OF THE NUCLEI IN THE
NERVE CELLS WHICH ARE RELATED TO MOTOR NERVES.

In an article which appeared in the Journal of Nervous and Mental
Disease, Jan., 1880,* I published the fact that the nuclei, in the large
nerve cells of the frog's crural enlargement, were larger than those in
the similarly placed cells of its brachial enlargement, giving, at the same
time, the measurements of these elements in micrometer divisions.

The difference in average size was considerable ; and believing, then
as now, that exact measurements of nuclei are more satisfactory than un-
certain and widely varying dimensions of the irregularly shaped masses
of surrounding protoplasm, I was encouraged to extend my researches
to the nerv^e centres of many other animals, and to the nuclei in the sup-
posed cells of origin of the cranial motor nerves.

Prior to this time no similar observation had been made. Both
Reissner and Stieda — the former, treating of the central nervous system
of the frog, and the latter, of the spinal cord of the turtle — publish, in
millimeters, diameters of nuclei in the nerve cells, but without compar-
insr the average size either of the cells or of their nuclei in the two en-
largements of the cord, or in the ganglia of the encephalon.

No attempt has been made b}' either one of these writers to con-
nect the dimensions of these elements with differences in motor energy
developed in the related muscles.

* See the same journal for July, iSSo, Jan., iSSi & Jan., 1SS3.

23 NUCLEI IN THE NERVE CELLS.

Between January- and July, 1880, comparative measurements of
nuclei in other species were made, and it was found that, in the gopher
turtle, — land species — the nuclei in the large nerve cells of the spinal
cord were larger, in the cei'vical, than in the lumbar region. The pow-
er of the muscles of the anterior limbs, in this species, considerably ex-
ceeds that of the posterior limbs.

Measurements of the nuclei in the cells related to the cranial motor
nerves, in frogs, alligators, lizards and turtles, gave still stronger evi-
dence of the existence of a law, the wording of which, as first formu-
lated, was then changed so as to make it more comprehensive, and to
read : Tlie nuclei of the so-called motor cells of the central nervous system,
have, in the same individual, average diameters which are proportional to
the power developed ijt the related muscles.

No valid objection to this proposition has yet appeared from any
quarter, while verifications have steadily accumulated.

In stating, at first, what seemed to be true in regard to the spinal
cord of the frog and gopher turtle, the word extremities was used in-
stead of the word muscles. The latter is of wider application and has
since been thought to agree with the facts obsen'ed, in another interest-
ing particular. For example : In the green turtle, the anterior extrem-
ities are much more complex in their functions, and are supplied with
more muscles than the posterior extremities ; while the separate muscles
appear no larger than the corresponding ones of the posterior extremities.
The same thing is true of the bat ; and in both of these animals, there
is little or no difference between the dimensions of the cervical and lum-
bar nuclei, although in the cervical region of both animals, the large
cells are several times more abundant.

The most striking confirmations of the above rule are to be found
in the cells of origin of the cranial motor nerves, in all the species so far

NUCLEI IN THE NERVE CELLS. 24

examined, and in the spinal cord of the frog and gopher turtle, in which
animals the number of muscles is practically the same for both pairs of
extremities.

It is possible that a correspondence also exists between the number
of nuclei (or cells) and complexity of function, or number of muscles.

Plates XCIX. — CXIII. simply illustrate a few of the most promi-
nent facts in regard to the comparative dimensions of nuclei, no claim
being made that these photographs from single sections demonstrate the
average which has been obtained by the study of a large number. The
nuclei in the cells of origin of the oculomotorius are remarkabi}' well
shown in Plate CX. and may be satisfactorily compared with those in
Plate CXI. — origin of the motor root of the trigeminus — snapping turtle.

I have photographs which show these nuclei from the iguana indi-
cating a difference of the same kind, but less in degree.

The numbers in parentheses, at the close of the list of plates, will
enable the reader to find those photographs which have been taken from
the same individual and with the same magnifying power.

No sympath}- with any theory which claims to distinguish between
motor and sensory cells is here implied, nor does the writer insist upon
any special anatomical importance for the nuclei, as compared with the
cell bodies, beyond their more distinct and regular outline which makes
them very conspicuous and hence well adapted to accurate micrometric
observation. That the nuclei are the true functional centres of the
nerve cells is at best an unproved hypothesis ; but comparative meas-
urements of these bodies are facts which seem very essential to the fu-
ture understanding of their function.

LITERATURE.

Hannover. Recherches microscopiques sur le System Nei-veux. Kopenhague,

1S44.

Blattmann. Mikroskopisch-anatomische Darstellung der Centralorgane des

Nei-vensystems bei den Batrachiern. Zurich, 1850.

Wyman. The Nenous System of Rana Pipiens. Smithsonian Conti-ibutions.

Washington, 1S53.

Bidder & Untersuchungen iiber die Textur des Riickenmarks. Leipzig,

Kupffer. 1S57.

KolHker. Vorlaufige Mittheihmg uber den Bau des Riickenmarks bei nie-

dern Wirbelthieren. Zeitsch. f. wissens. Zool. IX Bd. 1S5S.

Ecker. Icones Physiologicae. Leipzig, 1851 — 1859.

Mauthner. Ueber die sogenannten Bindegewebskorperchen des Centralen

Nervensystems. Sitzungsbericht d. k. Acad. d. Wissens. zu Wien,
1 86 1, XLIIIBd.

Traugott. Ein Beitrag zur feineren Anatomic des Riickenm. von Rana Tem-

poraria. Dorpat. 1S61.

Grim. Ein Beitrag zur Kenntniss von Bau des Riickenm. von Vipera Be-

rus Lin. Arch, fiir Anat. u. Phys. 1864.

Reissner. Der Bau des Centralen Nervensystems der ungeschwanzten Ba-

trachier. Dorpat, 1864.

LITERATURE.

Stieda. Studien iiber das Centrale Nei-vensystem d. Wirbelthiere. 1870.

Ueber den Ban des Centralen Nei-vensystems der Amphibien uiid

Reptilien. 1S75. Leipzig.

Miiller. Ueber Entwickelung und Ban der Hypopliysis und des Processus

Infuiidibuli Cerebri. Jenaische Zeitsch. f. Medicin. VI. Band
Leipzig, 1871.

Karabanowitsch. On tlie Stnicture of the Spinal Cord of the Frog. St. Petersburg,
1872. Private Translation from the Russian.

Rabl-Riickhard. Das Centralncrvensystem des Alligators. Zeitschrift fiir wissen-
schaftliche Zoologie, III Bd., s. 336. 1S7S.

Ueber das Vorkommen eines Fornixrudiments bei Reptilien. Zo-

ologisher Anzeiger, 30tn., Mai, 1881.

Spitzka. The Brain of the Menobranchus. Journal of Nervous and Mental

Disease, July, 1878, p. 478.

The Architecture and Mechanism of the Brain. Chap. II. pp.

407-437. Same Journal, July, 1880.

The Brain of the Iguana. "Science," August, 14th., 18S0.

Further Notes on the Brain of the Iguana and other Sauropsidae.

"Science," February, 19th., 1881.

Schmidt. On the Stmcture and Function of the Ganglionic Bodies of the

Cerebro-spinal Axis. Journal of Nei-vous and Mental Disease,

January, 1879.

Mason.

A New Group of Nerve Cells in the Spinal Cord of the Frog.
New York Medical Journal, Dec, 1879.

Microscopic Studies on the Central Nei-vous System of Reptiles
& Batrachians. Journal of Nervous and Mental Disease, 4 Articles,
Jan. & July, 1880, Jan. 1881, Jan. 1882. Also Note, July, 1S81.

LIST OF PLATES WITH THEIR AMPLIFICATIONS

IN DIAMETERS.

SPINAL CORD.

ANIMAL.

SUBJECT.

AMPLIFICATION.

NO. OF PL.

Alligator.

Cer\ical Enlargement.

Magnified 30 Diameters.

I,

Li.

Lumbar "

i. i.

30

a

II,

(<

Inferior Roots, (Cen-ical)

L >.

150

a

III,

((

" (Lumbar)

((

150

u

IV,

U

(6 mos. old.) 4 Sections.

h b

40

((

V

Heloderma,

4 "

41

32

u

VI

Anolius.

Cervical Enlargement.

U

112

1.1.

VII

u

Lumbar "

t(

112

a

VIII

Phrj-nosoma. Cenical "

a

100

i.1.

IX

ii.

Lumbar "

a

100

a

X

Scincus.

Cervical "

ii

no

a

XI

ii.

Lumbar "

ti

no

ti

XII

11

4 Sections.

<.(.

40

it.

XIII

Serpents.

4 " i-ii, 6i

5, III-

rv, 12

a

XIV,

Spilotes.

Lateral Ligament. Longit

. Sect

. 130

a

XV.

Testudo.

Cenical Enlargement.

Ma,

gnified 75

a

XVI

a

Lumbar "

u

75

li

XVII

1. (.

Cei-\ical "

(C

"5

a

XVIII

Emj-s.

4 Sections.

.

u

28

a

XIX

Cistuda.

4 " ....

.

u

40

u

XX

Emj-s.

Dorsal Region.

u

100

li

XXI

Chelydra.

Cenical Enlargement.

1.1.

45

a

XXII.

ti b

Lumbar ' '

u

45

a

XXIII

u

Dorsal Region.

(

> It

65

it,

XXIV

i.L

Caudal " ...

'•<

65

li

XXV

LIST OF PLATES.

ANIMAL. SUBJECT.

AMPLIFICATION.

NO. OF PL

Rana. Brachial Enlargement.

Magn

tied 44 Diameters. XXVI

' ' Crural

1.1.

((

44

((

XXVII

" Filum Terminale.

ii.

I OS

a

XXVIII

" Ant. Dorsal Region.

fc fc

64

a

XXIX

" Group of Middle-Sized C

ells. "

^33

i b

XXX

" Crural En

argement.

t, b

133

((

XXXI

" Brachial

t. i.

t i

218

it

XXXII

(( ((

u

ii,

172

i i

XXXIII

(( ((

I.L

I b

75

(b

XXXIV

" Crural

i(.

a

75

li

XXXV

" Brachial

U

i.i

55

li

XXXVI

' ' Crural*

ii.

<.i.

120

ii

XXXVII

Menopoma. Cenical R

egion.

u

150

li

XXXVIII

" Lumbar

!.(.

1.1.

150

li

XXXIX

Caudal

(.i

bi

150

I k

XL

" Cenical*

ii

u

40

b I

XLI

Siren.

1(

(.i

150

li

XLII

" Dorsal

ii

11.

150

I i

XLIII

Caudal

u

li

150

U

XLIV

MEDULLA OBLONGATA.
Alligator. Ant. Cervical Region. Magnified 35 Diameters.

Med. Obi. Post. '^
Spinal Accessory.
Raphe Cells.
Eminentiae Acousticae.
Trigeminus. Motor R.

1 (

25
100

200
26

II

XLV.

XLVI.

XLVII.

XLVIII.

XLIX.

L.

"Longitudinal Section.

LIST OF PLATES.

ANIMAL.

SUBJECT.

AMPLIFICATION.

NO. OF PL

Alligator.

Vagus Magi

lifted 100

Diameters.

LI

U

Post. Region Med. Obi. '

30

LII

((

Eminentia Acoustica. '

40

LIII

Spilotes.

Hypoglossus. '

40

LIV

Nerodia.

It I

40

LV

Testudo.

Med. Obi. & Sp. cord. '

40

LVI

4i

Abducens '

50

LVII

Rana.

Trigeminus. Motor R. '

' 46

LVI 1 1

Menopoma

Near the Acoustic Nerves. '

150

LIX

i(

Trigeminus. Motor R. '

150

LX

((

Just behind the 4th Vent. '

60

LXI

Siren.

Vaofus '

ICO

LXII

CEREBELLUM.

Alligator.

Anolius.

Phrynosoma.

Scotophis.

Cistuda.

Rana.

Menopoma.

Vert. Longit. Section. Magnified id Diameters. LXIII.

ii.

h b

5°

LXIV

b 4

30

LXV

( fc

30

LXVI

£b

ii

LXVII

i^

45

LXVI 1 1

ii,

40

i> b

LXIX

OPTIC LOBES.

Heloderma. Vert. Trans. Section. Magnified 39 Diameters. LXX.

Phrynosoma, " " " " 30 '' LXXI.

Anolius. " " " " 41 " LXXII.

Nerodia. " " " " 30 '' LXXIII.

30

LXXIV.

LIST OF PLATES.

ANIMAL.

SUBJECT

AMPLIFICATION.

NO. OF PL

Crotalus. Vert.

Trans.

Section.

Magnified 32 Diameters.

LXXV

Spilotes.

u

a

25

a

LXXVI

Chelydra. "

u

((

26

a

LXXVII

Emys. "

u

u

150

a

LXXVI 1 1

Rana. "

a

((

27

a

LXXIX

a i(.

ii

ii

105

11

LXXX

li (4

a

(I

700

a

LXXXI

Diemyctylus."

a

li

60

u

LXXXII

Menopoma. "

a

a

45

b(

LXXXIII

(.(. ii.

a

a

150

a

LXXXIV

Siren.

a

a

50

i i

LXXXV

CEREBRAL LOBES.

Heloderma.

Vert. Trans

Sect.

Magni

tied 26 D

ameters

. LXXXVI

Scincus.

; b hi

4 4

44

47

4 4

LXXXVII

Anolius.

4 h 44

4 4

4 4

42

44

LXXXVIII

Nerodia.

44 44

44

44

30

44

LXXXIX

Cistuda.

44 44

44

4 4

26

4 4

XC

Rana.

44 44

44

(4

30

44

XCI

a

44 44

44

44

40

44

XCII

u

u 44

44

44

90

44

XCIII

(C

ii. 44

44

44

700

44

XCIV

((

Olf actor}- Lobes.

44

58

44

XCV

Menopoma.

Vert. Trans.

Section

44

38

44

XCVI

Siren.

44 44

4 4

4 4

48

4 4

XCVII

Diemyct^'lus

44 44

4 4

4 4

104

4 4

XCVI 1 1

LIST OF PLATES.
NUCLEI IN NERVE- CELLS.

ANIMAL. SUBJECT. AMPLIFICATION. NO. OF PL.

Alligator. Spinal Cord. . . . Magnified loo Diameters. XCIX.

" Trigeminus. Motor R. " loo " C.

" Oculomotorius. ... " 300 " CI.

" Trigeminus. Motor R. " 300 " CI I.

Raphe Cells " 300 " CIII.

" Eminentia Acoustica. " 300 " CIV.

Testudo. Optic Lobes '' 400 " CV.

" Abducens " 400 " CVI.

" Trigeminus. Motor R. " 400 " CVII.

Sp. Cord. (Cervical.) " 400 " CVIII.

" " " (Lumbar.) " 400 " CIX.

Chel3'dra. Oculomotorius. ..." 100 " CX.

" Trigeminus. Motor R. " 100 " CXI.

Rana. 4 Sections '' 220 " CXII.

Phrynosoma. Oculomotorius. . . " 100 " CXIII.

NUMBERS OF PLATES GROUPED. EACH GROUP REPRE-
SENTING SECTIONS MADE FROM THE SAME INDIVIDUAL AND
PHOTOGRAPHED WITH THE SAME MAGNIFYING POWER.

(I.-II.) (III.-IV.) (V. i-iv) (VI. i-iv) (VII.-VIII.)

(IX.-X. «& CXIII.) (XI.-XII.) (XIII. ■-IV) (XVI.-XVII.)
(XIX. I-IV) (XX. I-IV) (XXII.-XXIII.) (XXIV.-XXV.)
(XXVI. -XXVI I.) (XXXIV.-XXXV.) (XXXVIII.-XL., XLIL-
XLIV., LIX.-LX.) (XLIX.-L.) (LVI. i-iv) (XCIX.-C.)
(CI.-CIV.) (CV.-CIX) (CX.-CXI.) (CXII. I-IV)

ERRATA.

Under Plates XCII, XCIII & XCIV for 'Coipus Striatum'
and 'Corpora Striata' read 'Cerebral Protubei'ance' and Protu-
berances'.

Under Plate C for 'i Inch' read '1-3 Inch'.

.#

/'V-vj/

-vrii

I.

ALLIGATOR MISSISSIPIENSIS. SPINAL CORD.

TRANSVERSE SECTION FROM THE MIDDLE OF THE
CERVICAL ENLARGEMENT.
Gelatine Negative No. g. Griinow 2 Imh.

>Mi.

m

I

Wf.^

J

- ■% .. ■. . -y\, ■ I

II.

ALLIGATOR MISSISSIPIENSIS. SPINAL CORD.
TRANSVERSE SECTION FROM THE MIDDLE OF THE
LUMBAR ENLARGEMENT.
Gelatine Negative No. lo. Grtinow 2 Inch.

III.

ALLIGATOR MISSISSIPIENSIS. SPINAL CORD.

TRANSVERSE SECTION FROM THE MIDDLE OF THE

CERVICAL ENLARGEMENT.

INFERIOR ROOT-FILAMENTS AND COLUMN.

Gelatine Negative No. 65. Grunoiv 4-10 Inch.

.i-r^tfinr 1

vV

\ s

■■■ f

/. ;'

ail

:/

IV.

ALLIGATOR MISSISSIPIENSIS. SPINAL CORD.

TRANSVERSE SECTION FROM THE MIDDLE OF THE
LUMBAR ENLARGEMENT.
INFERIOR ROOT-FILAMENTS AND COLUMN.
Gelatine Negative No. ii. Gnimno 4-10 Ineh.

.<<sS^^^^^?5?s„„„..

'•'"SCxri,

u-/

"^.li:

II

^j.^jr^^.*rf>^^,^ft|?JWfi^^^

..«^'

"-<*■•,

"teSS

/

III

IV

V.

ALLIGATOR MISSISSIPIENSIS. SPINAL CORD.

I LUMBAR ENLARGEMENT, II DORSAL REGION,

III CERVICAL ENLARGEMENT, IV THROUGH THE

ROOTS OF THE SPINAL ACCESSORY NERVE.

Gclatiiu Negatives Nos. 130-133. Miller Bros, i Inch.

sr»

.1

"*^«i^^«r ^*^r"--;

II

III

i\r

VI.

HELODERMA SUSPECTUM. SPINAL CORD.

TRANSVERSE SECTIONS.
I CERVICAL REGION, II DORSAL, III CAUDAL, IV LUMBAR.
Gelatine Negatives Nos. IJ4-1J'/. Miller Bros. 1—1-2 Inch.

VII,

ANOLIUS CAROLINENSIS. SPINAL CORD.

TRANSVERSE SECTION FROM THE MIDDLE
OF THE CERVICAL ENLARGEMENT.

Gelatine A^egative No. 44. Miller Bros. 1-2 Inch.

VIII,

ANOLIUS CAROLINENSIS. SPINAL CORD.

TRANSVERSE SECTION FROM THE MIDDLE

OF THE LUMBAR ENLARGEMENT.

Gelatine Negative No. 45. Miller Bros. 1-2 Inch.

j>r

y '•* .'

^^v-v

\

wmmB

«a

".^

' '^

)' .

' ^"""^ \

1^

"* i:

f *='*

.^

IS •

1 > -^&.

^''-^

''-^■^•^

V 'Jt^^

r V"

• 'J

-1\

IX.

PHRYNOSOMA CORNUTUM. SPINAL CORD.

TRANSVERSE SECTION FROM THE MIDDLE
OF THE CERVICAL ENLARGEMENT.

Gelatine Nemtive No. 6o. Miller Bros. i-2 Inch.

c^scr?*"

^

'#^

> > ^

■■^5^

X.

PHRYNOSOMA CORNUTUM. SPINAL CORD.

TRANSVERSE SECTION FROM THE MIDDLE

OF THE LUMBAR ENLARGEMENT.
Gelatine Negative No. 6i. Miller Bros. 1-2 Inch.

, 4

~*«ib^::;,^ : ''\"'S- ' sn: ;^;nv>5^■

*•■-*aJii,i,,.

■M&'^"

XI,

SCINCUS ERYTHROCEPHALUS. SPINAL CORD.

TRANSVERSE SECTION FROM THE MIDDLE OF THE

CERVICAL ENLARGEMENT.

Gelatine Negative No. ii6. Miller Bros. 1-2 Inch.

-'. y.: - v' ■;'■'■ '\> ■

.„,, ■■.'■:• ■ ■■■■■'/

.y?

»*

XII,

SCINCUS ERYTHROCEPHALUS. SPINAL CORD.

TRANSVERSE SECTION FROM THE MIDDLE OF THE
LUMBAR ENLARGEMENT.

Gelatine Negative No. iij. Miller Bros. 1-2 Inch.

^.;

(.

/ :.

X;

.,/

/

II

-Ja?*-*-?!'

.\

■\

^\

V'

I

'**'^'''~"«:jrfaaSE.-»'^i-

'.^

III

XIII

TV

SCINCUS ERYTHROCEPHALUS. SPINAL CORD.

I ANT. CERVICAL REGION. II CERVICAL ENLARGEMENT.

Ill DORSAL REGION. IV LUMBAR ENLARGEMENT.

Gelatine Negatives Nos. 167-170. Miller Bros, i Inch.

'gxHy,

.S«V;fS^-;''

''#^¥M«ii

^;S^^©K??!S::'

^i«f

11

=i^p!WP«»ft.^.^

■ G

%A

'"'^s.iiiaS^giiEifo:

m^

III

IV

XIV.

SERPENTS. SPINAL CORD.

TRANSVERSE SECTIONS.

I Toxicopliis Pisck'oi-iis, Cervical Region. Miller Bros. 1-2 in.

II Crotalns Adamanteus,

III Nerodia Fascmta, " " '^ " / ///.

11 1.1.

IV

Dorsal Region.

Gelatine Negatives Nos. i^S-141.

^^^^^3^^^^^

^ffiK^^W

XV.

SPILOTES EREBENNUS. SPINAL CORD.

LONGITUDINAL SECTION SHOWING THE STRUCTURE OF THE
LATERAL LIGAMENT.

Gelatine Negative No. 8j. Miller Bros. i-2 Inch.

'*

.mr:

"4:

'■i'

/ /

•JifwKS' iiivP ' ' ?&w " ^ <-^

"^'trS^'-

/»

»>'

XV I,

TESTUDO POLYPHEMUS. SPINAL CORD.

TRANSVERSE SECTION FROM THE MIDDLE

OF THE CERVICAL ENLARGEMENT.

Gelatine Negative No. 64. Miller Bros, i Inch.

■.■.f:liSff^Xi^l^%^s0:fr,- .

■ ~ ^'^='- - "

-'■■ ■■■■■ ^- ■ , . ;V, ' . ,;' ^ - • ..'^^g

:da

■a ■-•■' -'~?..

n-:..

m.

^ ,^'

sr.'^-

.■i^ •'.'-V^'"' -i/'-^V-'"-- ■

^. ^,\

?l&

^■

'fe;';

> -r

■' ■. '' ""''f

'rV;-

',ii&^.
•s;:;

'''■^^'/'. ^?->vS-'V -v^'

.■^Sl^^'^";'-

;'P

XVII,

TESTUDO POLYPHEMUS. SPINAL CORD.

TRANSVERSE SECTION FROM THE MIDDLE
OF THE LUMBAR ENLARGEMENT.

Gelatine Nemtive No. 6 ;

Miller Bros, i Inch.

. iM^

i?-

. ";'.'*';i»;-*"-7*.'.'>»<'..

XVIII.

TESTUDO POLYPHEMUS. SPINAL CORD.

TRANSVERSE SECTION FROM THE MIDDLE

OF THE CERVICAL ENLARGEMENT.

Gelatine Negative No. 6j. Miller Bros. 1-2 Inch.

■-AiJ''?^;>a-v*':.-. i-Ti'Sii^.

II

III

IF

XIX.

EMYS TERRAPIN. SPINAL CORD.

TRANSVERSE SECTIONS.

I. CERVICAL REGION: II. DORSAL: III. LUMBAR: IV. CAUDAL.

Gelatine Negatives Nos. 92-^^- Miller Bros, i Inch.

^eS-

II

"'■S^'^^'V*-"

III

IV

XX.

CISTUDA CAROLINA. SPINAL CORD.

I CERVICAL ENLARGEMENT. II SHOWS FLATTENING OF
THE MYELON JUST BEHIND THE CERVICAL ENLARGEMENT.
Ill POST. DORSAL REGION. IV LUMBAR ENLARGEMENT.

Gelatine Negatives Nos. 163-166. Miller Bros, i hich.

'S0m^^m:'

XXI.

EMYS FLORIDANA. SPINAL CORD.

STRUCTURE OF THE GRAY SUBSTANCE IN THE
DORSAL REGION.

Gelatine Negative No. 5/. Miller Bros. 1-2 Inch.

\

'^.

V

XXII

CHELYDRA SERPENTINA. SPINAL CORD.

TRANSVERSE SECTION FROM THE MIDDLE OF THE

CERVICAL ENLARGEMENT.

Gelatitie Negative Ao. 12^. Grunow 2 Inch.

Sti>.

XXIII.

CHELYDRA SERPENTINA. SPINAL CORD.

TRANSVERSE SECTION FROM THE MIDDLE OF THE

LUMBAR ENLARGEMENT.

Gelatine Nemtive No. 126. Griaicnv 2 Inch.

,isss0m-;SM&!W^mM&A^.^

/"i''

%i^

^:,o.

:'0'

""^mmMm^

)i^

%

.%'<•■ ■

XXIV.

CHELYDRA SERPENTINA. SPINAL CORD,

TRANSVERSE SECTION FROM THE

DORSAL REGION.

Gelatine Negative No. 127. Gninuxv 2 Inch.

<j^Mif'-

■k

XXV.

CHELYDRA SERPENTINA. SPINAL CORD.

TRANSVERSE SECTION FROM THE
CAUDAL REGION.
Gelatine Negative No. 128. Gniiww 2 Inch.

f

"^""^"SMmnmsMSi

XXVI,

RANA PIPIENS. SPINAL CORD.

TRANSVERSE SECTION FROM THE MIDDLE OF THE
BRACHIAL ENLARGEMENT.

Gelatine Negative No. 41. Miller Bros, i Inch.

XXV I L

RANA PIPIENS. SPINAL CORD.

TRANSVERSE SECTION FROM THE MIDDLE OF THE

CRURAL ENLARGEMENT.

Gelatine Negative No. 40. Miller Bros, i Inch.

''■•%<■ ; ''- '■ ^r"'- ■' ':'^''-^':;"' "*^ V

S#

XXVI I L

RANA PIPIENS. FILUM TERMINALE.

TRANSVERSE SECTION.

Gelatine Negative No. 32. Miller Bros. 1-2 huh.

->>.

'-•^.

/-?•/■ a;

•• : .V-

i'

XXIX.

RANA PIPIENS. SPINAL CORD.

TRANSVERSE SECTION OF THE ANTERIOR DORSAL REGION,

SHOWING, ON EITHER SIDE. THE GROUP OF

MIDDLE-SIZED CELLS.

Gelatine Negative No. j6. Miller Bros, i Inch.

0¥$

.if:. ^ *y\^-' (J?

r 'I

v;j

='>*V.^ '*'

•^ '*

'■,.f

' \

»»'

V

«b

<*&

'

u *■

.^

' * .

(•^v.y,.')''

''' >.: I

" I. • 111'/''' i, l'''"-!.'.'\M

XXX.

RANA PIPIENS. SPINAL CORD.

SAME CELL-GPvOUP AS THAT SHOWN IN PLATE XXIX.

FR0^4 ANOTHER SPECIMEN.

Gelatine Negative No. 122. Miller Bros. 1-2 Inch.

'a

J^.\-

<**!

-^

^'f'

^^^

11

>l

\ J*.

„-..^

>

0 1

,;,^c>,t;^^:;^^^^^'

r «, /;

^^

■jgjf"

XXXI.

RANA PIPIENS. SPINAL CORD.

TRANSVERSE SECTION FROM THE CRURAL ENLARGEMENT.

INFERIOR HORN, GANGLION CELLS, NUCLEI OF

CONNECTIVE TISSUE AND CENTRAL CANAL.

Gelati7ie Negative No. no. Miller Bros. i-2 Inch.

v

'-'^.

-i*-

^sS.^'^.f.

'•'ffe?*j«*>5S«^'-- ■ '/ ■■•• '^^J f/> =W .-^ '-'^

XXXII.

RANA PIPIENS. SPINAL CORD.

TRANSVERSE SECTION FROM THE BRACHIAL ENLARGEMENT.
CENTRAL CANAL AND SUBSTANTIA RETICULARIS.

Gelatine Negative No. 77. Miller Bros. 1-2 Inch.

..,«*.. j<ia!\/.- -'■ J -.*v--i. . .

J'-''':"^; V

•V t

„*•.:/ ''If*

'k ' '■"

#^. :-V -■-

-V ■>^.'

■ K"

>>

N

XXXIII.

RANA HALECINA. SPINAL CORD.

TRANSVERSE SECTION FROM THE BRACHIAL ENLARGEMENT.
INFERIOR ROOT-FIBRES AND GANGLION-CELLS.

Gelatine Negative No. ii^. Miller Bros. i-2 Inch.

'./

5.^*;

1 ' 3^

■Vv'^^. >- -'

<#

•- ,^'»-;

■■■ -v ■

Pif^;

^,:%->

-.#

?'■'<■"'>■'' -V^'V, '•%v,''''l'-

'iH.

,^#

■ ^^'Sdx^S^0^'^

XXXIV.

RANA PIPIENS. SPINAL CORD.

TRANSVERSE SECTION FROM THE MIDDLE OF THE
BRACHIAL ENLARGEMENT.

Gelatine Negative No. I2j. Aliller Bros. I Inch.

i'rt

Xiu

'«

SI

3

^^

^»

^

K f

s&^^Ut^^"*'

■%J

'-^r'-v

IT

XXXV.

RANA PIPIENS. SPINAL CORD.

TRANSVERSE SECTION FROM THE MIDDLE OF THE

CRURAL ENLARGEMENT.

Gelatine Negative No. i2j. Miller Bros, i Inch.

^^ -T^^Stef,.

'^

\ r

^t'^>"

\ /

fc ■

/ -I

'4^.

-ii>''^*^'

w

XXXVI.

RANA HALECINA. SPINAL CORD.

TRANSVERSE SECTION THROUGH THE MIDDLE OF THE
BRACHIAL ENLARGEMENT.

Gelatine Negative No. iji. Miller Bros, i hich.

'•*\^>;^i-. .:■■.

..'t

^^v"

v~ , /

. A ^

Mi.

■5 >;' ■??;"

>>:.'

■iS,

:V?fc^:

^^a^^^fc'

iS^^&^^:^'^^^^^

XXXVII

RANA PIPIENS. SPINAL CORD.

LONGITUDINAL OBLIQUE SECTION THROUGH THE

CRURAL ENLARGEMENT.

GANGLION-CELLS AND THEIR NUCLEI.

Gelatme Negative No. 8i.

Miller Bros. 1-2 Inch.

XXXVIII.

MENOPOMA ALLEGHENIENSE. SPINAL CORD.

TRANSVERSE SECTION NEAR THE NERVES SUPPLYING THE

ANTERIOR EXTREMITIES.

Gelatine Negative No. 1^4. Miller Bros. I -2 Inch.

XXXIX.

MENOPOMA ALLEGHENIENSE. SPINAL CORD.

TRANSVERSE SECTION NEAR THE NERVES SUPPLYING THE

POSTERIOR EXTREMITIES.

Gelatine A'cgative No. ijj. AliUer Bros. i-2 Inch.

r

XL.

MENOPOMA ALLEGHENIENSE. SPINAL CORD.

TRANSVERSE SECTION NEAR THE MIDDLE OF THE
CAUDAL REGION.

Gelatine Negative Ne>. IJJ. Miller Bros. 1-2 Inch.

."^ '' -,' " '■'■"■'-■■""■J-rf^-:?^"''^'-'' -'' '- l~'1^^

'^^•■^~~'V*f-si

XLI.

MENOPOMA ALLEGHENIENSE. SPINAL CORD.

VERTICAL LONGITUDINAL SECTION.

Ge/c7/i,ie Negative No. 194. MUkr Bros, i Inch.

j?iil V'-- r'.'i'^ -V; -T? -Iir'^-- *

''i^''^^<

XLII.

SIREN LACERTINA. SPINAL CORD.

TRANSVERSE SECTION THOUGH THE CERVICAL REGION.
Gelat'me Negative No. 1S7. Miller Bros. 1-2 Inch.

■ ;■■'■■ •,■4'-:-

A

<?• *

S^ •.■•'<^^^Vtt* •,. -1 /•'•.- .:■--' t-/.-' • '. .- *v.™; r'' .■•--■ '*-;.■.■ # # - ^ ■'- -*~~^

XLIII

SIREN LACERTINA. SPINAL CORD.
TRANSVERSE SECTION THOUGH THE DORSAL REGION.

Gelatine Negative No. ijg. Miller Bros. 1-2 Inch.

_ ^ tk* M mm

i'^rrrj.;^.- it.-^~'.ui ,",'•'.» ^ -i.r-.. ■ ^vV-'^^-'-^w ;.V -.-■.- . T '•;, -v. •.•:•.•■>." .•.,,-. •-..■ .-.,. «..••. - . ••

XLIV.

SIREN LACERTINA. SPINAL CORD.

TRANSVERSE SECTION OF THE CAUDAL REGION.
Gelatine Nemtive No. 1 88. Miller Broi. 1-2 Inch.

A

XLV.

ALLIGATOR MISSISSIPIENSIS.

TRANSVERSE SECTION OF THE SPINAL CORD NEAR THE

MEDULLA OBLONGATA.

Gelatine Negative No. I2(). Miller Bros. I Imh.

^

-^''

a%:

■^-5^J's.:?r^-

XLVI.

-.fe.

,:»^

ALLIGATOR MISSISSIPIENSIS.

TRANSVERSE SECTION MADE ABOUT ONE CENTIMETER

BEHIND THE FOURTH VENTRICLE.

Gelatine Negative No. ijo. Miller Bros. 21-2 Inch.

a.

XLVII

ALLIGATOR MISSISSIPIENSIS. MEDULLA OBLONGATA.

TRANSVERSE SECTION. CELLS OF ORIGIN AND FIBRES OF THE
SPINAL ACCESSORY NERVE.

Gelatine Nemtive No. iii. Miller Bros. 1-2 Inch.

%v

^Mi

M/>^'

t

XLVIII

ALLIGATOR MISSISSIPIENSIS. MEDULLA OBLONGATA.

LARGE CELLS IN THE RAPHE.
TRANSVERSE SECTION MADE JUST BEHIND THE
AUDITORY NERVE.

Gelati7ie Negative No. i. Miller Bros. 4-10 Inch.

'■*■ /I'-

-<^

■"*;

■x^^j^

XLIX.

ALLIGATOR MISSISSIPIENSIS. MEDULLA OBLONGATA.

TRANSVERSE SECTION. CELLS OF THE EMINENTI^ ACOUSTIC/E

AND OF THE RAPHE.

Gelatine Negative No. 54. Miller Bros. 2--- 1-2 Inch.

^^i:"^

~m

ff

,uii^

L.

ALLIGATOR MISSISSIPIENSIS. MEDULLA OBLONGATA.

TRANSVERSE SECTION. CELLS OF ORIGIN AND FIBRES OF THE
MOTOR ROOT OF THE TRIGEMINUS.

Gelatine Negative No. J2. Miller Bros. 2—1-2 Inch.

>*•?■•' ^ ■' SS> ■ •■;;;■■ ■*''^^--' . ,^,,'' ■■ • ': *«»■.::::'; ,\J; ,■;'v^)^^fe•T>^-•^,K•C

t-v;;--^, ■ :i

ft^'i;*--

-^:^^::'

" /; «i«.-

*r.:,.\^(r

■t) ;-i*;':

^ ...

,.'*'.'f ■ /■■■,.- ••■•.... < l.-l V..*v

LI

ALLIGATOR MISSISSIPIENSIS. MEDULLA OBLONGATA.

TRANSVERSE SECTION. SHOWING THE PROBABLE ORIGIN
OF A NERVE BUNDLE FROM THE VAGUS.

Gelatine Negative No. 1 14. Miller Bros. 1-2 Inch.

:SSS^;0&.S^^^^^^^^^ .

£

■■^,

LI I.

ALLIGATOR MISSISSIPIENSIS.

TRANSVERSE SECTION OF THE MEDULLA OBLONGATA

MADE THROUGH ITS POSTERIOR PART.

Gelatine Negative No. ij6. Miller Bros. 2 1-2 Iiieh.

•■■;v.>.^m.

:•■■ A , •' ' '

'■.; M.;* V i-

>., I '/.'/ii?.'.!

' m V

■ ^

' . 7

■:lf^:;-

/;■ ■<■^^r•C^'r•.•^"-

nWv./V/

>&■*■''

'iEJifJSt'J*"*^

Llll.

ALLIGATOR MISSISSIPIENSIS.

VERTICAL LONGITUDINAL SECTION OF THE

MEDULLA OBLONGATA. EMINENTIA ACOUSTICA.

Gelatine iVega/ive N'o. 184. Miller Bros. 21-2 Inch.

■ '■ ''■■Vi\%'S!^

„^'J.,- %■

A-rf:

,

/»-'

''0,

'./

/

I '

%„

- ,.

'''■,'<■

K'^t

; 3 ' . ■'-

r-^' '■/ '

'•;■'■*- ■■-

|i

il

';

'-_

j>-'y''

,1

■i?'

■-^■' ■; **^'-^ ■

■\*b''4'i'''

*)feft>'?^

■ ' .-•■r^''*^--

•1«i "vi

.',' v'^' ^,

"* '■ ■''.'

,' ■>

V "■' ■'' '' '■ ■' '*■'"'

*■,■/'' '.^(b

' ' ■ A'

!■

■, t- \''\^vi

'; iV*''^/

f-

-V^

:'^

Vvl^^i^

■■■'•

s- ' r

'■ ' '■ ;•, ' ;. ■

N ' ,';:'

ii^-^^

".- "■^-\' ' \-''-'' ■■

"V

X;V'-

■(.yc'""

^ -"^ , ■.!'■-'/■ :■'

'.-■..-■l' .

',V"

' / " '

"V'

■^"-^' -.,■■'' ,

\

^: :

- , : ' " "■ ■-

-? - '^^Q-

1,.

>;:?;-, -.:■

' '' *^->i-

■ <.

LIV.

y-

SPILOTES EREBENNUS.

TRANSVERSE SECTION OF THE MEDULLA OBLONGATA

NEAR THE HYPOGLOSSAL NERVES.

Gelatine Negative No. g8. Miller Bros, i Inch.

LV.

NERODIA FASCIATA.

TRANSVERSE SECTION OF THE MEDULLA OBLONGATA

NEAR THE HYPOGLOSSAL NERVES.

Gelatine Netrative No. i8o. Miller Bros, i Inch.

^f^^^' ^^^^ht^

II

~:::S' ■■'.:•-

^

^.

r

ifp^'

m

■^Hi^-.

Ill

LVL

IV

TESTUDO POLYPHEMUS. TRANSVERSE SECTIONS.

I LUMBAR, II CERVICAL ENLARGEMENT. SPINAL CORD.

Ill THROUGH THE SPINAL ACCESSORY NERVES.

IV MOTOR ROOT OF THE TRIGEMINUS.

Gelatine Negatives Nos. i^g-162. Miller Bros, i Inch.

c
c

k--

m:

r

■:9WV'

■j^S&S^Sl^^^^v

LVII

TESTUDO POLYPHEMUS. MEDULLA OBLONGATA.
MODE OF ORIGIN OF THE ABDUCENS.

Gelatine Negative No. igj. Miller Bras, i Inch.

• "^*^-:

• :■..''{■•.■

W^J:

^^^^j'^&~

.'.-7>.;CVk:-.-;

' V-S

1^

•l^*'*'"-

■^«

l-i-r-SftsSS-i.

"'r !:'{■

i'?'t<i,l..i'^

•>';

LVIII.

RANA PIPIENS.

CELLS OF ORIGIN AND FIBRES OF THE MOTOR ROOT
OF THE TRIGEMINUS. CEREBELLUM ABOVE.

Gelatine Negative No. ^g. Miller Bros, i Inch.

:3

'r'f

•^ii

■*

■m ' .■-, ■ :■■■ .■■:'•■..■.■

.;*■■'•

■ ,■■•:■■ ■'■':'

''^m

:'■"-';■■' .■■■ ■ '.»■"■

■ ■ -*.

'v'.v- V,

>!, ..' \

s;^;-'^,"

^feis

''*^'''^;<ii'*'4'v

^l

.V* '

:*•■■■> '

LIX.

MENOPOMA ALLEGHENIENSE.

MEDULLA OBLONGATA. SECTION MADE NEAR THE

ACOUSTIC NERVES.

Gelatine Ncmtive No. iSi. Miller Bros. 1-2 Inch.

-^^;>,

%';^^-:vV

•^•

|^^K8i#fi.;"^.-'

■■^;:;';Sl«:viS:

--.-■v. ■>:

■■;-:>.

:i?^r

■■ ■: -.•■■■.■."v-'^'i-^fe' ■ ■■.' ■ ' ■

;.1ii-->

■ <v

**

-■^V; •■.:

^-i^-"'

LX.

MENOPOMA ALLEGHENIENSE.

MEDULLA OBLONGATA. CELLS OF ORIGIN OF THE

MOTOR ROOT OF THE TRIGEMINUS.

Gelaime Negative No. 182. Miller Bros. 1-2 Inch.

f^'.t/*4lfe

\

1 '' CD

i.^j^'^ .,,c«'/*''^''».*J^'"'-%"^'«*~'V '■€'>

■t^s

^^n-'^

t

1 >jk <

LXI,

MENOPOMA ALLEGHENIENSE.
MEDULLA OBLONGATA. TRANSVERSE SECTION
MADE JUST BEHIND THE FOURTH VENTRICLE.

Gelatine Negative No. iSj. Miller Bros, i Iitch.

♦ . ■■;(♦

^^^

^^

apl

■»«; : .^;

f

■■■.^'

■M::':

'■\:

VC

■i*/''

LXII.

SIREN LACERTINA. MEDULLA OBLONGATA.

TRANSVERSE SECTION NEAR THE VAGUS.
Gelatine Negalive No. /(pj. Miller Bros. 1-2 huh.

^St5BSf»i'S5NS»v!^'^if'^&;\'

■^-"

.\

LXIIL

ALLIGATOR MISSISSIPIENSIS. CEREBELLUM.

LONGITUDINAL VERTICAL SECTION.
Gelatine Negative No. 142. Miller Bros. 2 1-2 Inch.

.'■=^

j^\r

:-M:

\t\/

''%SilS>ti^.

LXIV.

ANOLIUS CAROLINENSIS.

LONGITUDINAL VERTICAL SECTION THROUGH THE
CEREBELLUM AND OPTIC LOBES,

Gelaime Negative No. §8. Miller Bros, i 1-2 Inch.

«f^.

- -X

,{

.^y^-*;;

LXV.

PHRYNOSOMA CORNUTUM.

LONGITUDINAL VERTICAL SECTION THROUGH THE
CEREBELLUM, OPTIC LOBE AND CEREBRUM.

Gelatine Negative No. 57. Miller Bros. 21-2 Inch.

LXVI.

SCOTOPHIS QUADRIVITTATUS.

LONGITUDINAL VERTICAL SECTION THROUGH THE
CEREBELLUM AND OPTIC LOBE.

Gelatine Negative No. 105. Miller Bros. 2 1-2 Inch.

LXVII.

CISTUDA CAROLINA.

LONGITUDINAL VERTICAL SECTION THROUGH THE
CEREBELLUM AND OPTIC LOBE.

Gelatine Negative No. 143. Miller Bros. 2 1-2 Inch.

:-.5?:Spi*Sg%v«^-i;;.v;.,

m>^r

^•■A
%'

:■■;•••%

^C'^

t'\^H?

■i;

. -'A

\.

'«" ,

■-^f;-/

'^^^^^

a-;- -

■ i'-'"'.-''

LXVIII.

RANA PIPIENS.

LONGITUDINAL VERTICAL SECTION THROUGH THE
CEREBELLUM AND OPTIC LOBE.

Gelatine Negative No. j8. Miller Bros, i Inch.

.-.■Si

'^^"^."^ik ,

"*,

>*

^f4'^^

Vi

^.

LXIX.

MENOPOMA ALLEGHENIENSE.

VERTICAL LONGITUDINAL SECTION THROUGH THE

CEREBELLUM AND OPTIC LOBE.

Gelattne Negaih'c No. iSj. Aliller Bros. I Inch.

■'%"

X

•fc'-

\

m.

■■•%^

''f^\

1

^

B

LXX.

HELODERMA SUSPECTUM.

TRANSVERSE VERTICAL SECTION THROUGH THE

OPTIC LOBES INCLUDING FIBRES AND CELLS OF ORIGIN

OF THE THIRD PAIR OF CRANIAL NERVES.

Gelatine Nemtive No. 1 08. Miller Bros. 21-2 Inch.

r-ir

''L..<

%

%?

^"

N..

LXXI.

PHRYNOSOMA CORNUTUM.

TRANSVERSE VERTICAL SECTION THROUGH THE

OPTIC LOBES. OPTIC NERVES BELOW.

Gelatine Negative No. jj. Miller Bros. 21-2 Inch.

•■i^S^^^-

\'

"mi

'm' ^

i?l'

,v:.<.'-^:S?^;;i^'

..c-^-
V'..^*-

Y-

LXXII.

ANOLIUS CAROLINENSIS.

TRANSVERSE VERTICAL SECTION THROUGH THE
OPTIC LOBES.

Gelatine Negative No. 145. Grunow 2 Inch.

<^

\.. y- .Z'

■:^

'^^^. -■■.■*''**^->

LXXIII,

NERODIA FASCIATA.

TRANSVERSE VERTICAL SECTION THROUGH THE

OPTIC LOBES INCLUDING THE THIRD PAIR OF

CRANIAL NERVES.

Gelatine Negative No. p/. Miller Bros. 21-2 Inch.

'f ;■' -^

: :^

LXXIV.

NERODIA FASCIATA.

TRANSVERSE VERTICAL SECTION THROUGH THE

OPTIC LOBES A LITTLE IN FRONT OF LXXIII.

Gelatine Negative No. loi. Miller Bros, 2 1-2 huh.

rtiia(a«;^'WW8«?ias«t«v >

■lis.-

LXXV.

CROTALUS ADAMANTEUS.

TRANSVERSE VERTICAL SECTION THROUGH THE

OPTIC LOBES INCLUDING FIBRES OF THE THIRD PAIR OF

CRANIAL NERVES.
Gelatine Negative No. 146. Miller Bros. 21-2 huh.

\y

t*^Ki

«'►•;. ^ '-M^M-

'.t

¥

•WV.-'*^'^

,- <f

f/

LXXVI.

SPILOTES EREBENNUS.

TRANSVERSE VERTICAL SECTION THROUGH THE

OPTIC LOBES INCLUDING FIBRES OF THE THIRD PAIR OF

CRANIAL NERVES.
Gelatine Negative No. p6. Miller Bros. 21-2 Inch.

>, -"Xi

v4^

■X

i-

■k-'

^^1

^-^.-;^a/ - -

^^>'i^^^p^^

LXXVII

CHELYDRA SERPENTINA.

TRANSVERSE VERTICAL SECTION THROUGH THE

OPTIC LOBES INCLUDING FIBRES AND CELLS OF ORIGIN

OF THE THIRD PAIR OF CRANIAL NERVES.

Gelatine Negative No. 144. Miller Bros. 2 1-2 Inch.

s';^^>

'*■'■.

^'^.

^.

TW-

0r'

•SI-x

•»rf

"'^U^^f'

LXXVIII.

EMYS FLORIDANA.

GANGLION IN THE "ROOF" OF THE OPTIC LOBES.

TRANSVERSE VERTICAL SECTION.

Gelatine Negative No. 56. Gnmmv 4- 10 Inch.

-iL-^S^'S*^^;

^ ■y/'-'r^y-.^y^i^y:

^41

LXXIX.

./■"

RANA PIPIENS.

TRANSVERSE VERTICAL SECTION THROUGH THE

OPTIC LOBES JUST BEHIND THE THIRD PAIR OF

CRANIAL NERVES.

Gelatine Negative No. 66. Miller Bros. 21-2 Inch.

1*

'% A J* ' r: Y

•\%

- - ^ ■•-»-vr,:<-:'». -■ -■■.—

.-1 ' -■ ■•'

?!l

■•'':4-*.-,.. .;f-=s.

:^i

LXXX.

RANA PIPIENS.

STRUCTURE OF THE OPTIC LOBES

FROM A SECTION LIKE THAT SHOWN IN PL. LXXIX.

Gelatine Negative No. 147. Miller Bros. 1-2 Inch.

•^

I'lPi

f

>\i\^

♦'«■

*. '*

•►^ *• »

. -^ ' •*»"* «^^

-4

.«P^

-»■.:

LXXXI

RANA PIPIENS.

STRUCTURE OF THE OPTIC LOBES

FROM THE SAME SECTION AS THAT SHOWN IN PL. LXXX.

Gelatine Negative No. toj. Nachct 7 Immersion.

.^-drfi>^. -^

''■»■ ■ ^ >'■■.-

LXXXII.

DIEMYCTYLUS TOROSUS.

TRANSVERSE SECTION OF THE OPTIC LOBES.

DISTOR TED IN HARDENING.

Gelatine Negative No. 155. Miller Bros, i Inch.

> : < .

^ *>

■ar:

OV^

'*6 W*

- V.

A

' ♦,

V ■■ I?* 9 '4-'. ■^3'..* ' :?-

lt4s^^*

-.iiisaS^''

LXXXIII.

MENOPOMA ALLEGHENIENSE.

TRANSVERSE VERTICAL SECTION OF THE OPTIC LOBES.
Gelatine Negative No. i8g. Miller Bros, i Inch.

^

I

:«#i

I

i^

LXXXIV.

MENOPOMA ALLEGHENIENSE. OPTIC LOBE.
FROM A SECTION LIKE THAT SHOWN IN PLATE LXXXII
Gelatine Negative No. igo. Miller Bros. 1-2 Inch.

»•

J*

'A

c»» *%

'<K-.

yj.^Vn

*I1!-

j',i#

LXXXV.

SIREN LACERTINA. OPTIC LOBES.

VERTICAL TRANSVERSE SECTION.
C'latine Negative No. jg2. Miller Bros, i Inch.

'■"^,

\

X-

•3r

A

f

I !J

:#'/ Jr

%

s.

LXXXVL

HELODERMA SUSPECTUM.

TRANSVERSE VERTICAL SECTION THROUGH THE

MIDDLE OF THE CEREBRUM.

Gelatine Negative No. log. Miller Bros. 21-2 huh.

■•= ^"JM^

■*-■.: •&'

■■■-., Y s&.

\%\

"^, ' ''i

■« 3;;|i^;

!^:r

- '0-'-A

,:V' ^^'. ^^r- '

''■:■ .V-',> V.' ' "^^7-

^ 'A

Ivi'

..... r,'J' \: .%-

t:^

"•

- . >.?.'

';

., -a?" ■

.' .

, 7 ■ ' ^i

^:

W:

• < vif^.i-;--

. *..•» -j^u":.

->.*

v,\~

■i-^-^

-^-- K«>

LXXXVII.

SCINCUS ERYTHROCEPHALUS.

TRANSVERSE VERTICAL SECTION THROUGH TH-E

MIDDLE OF THE CEREBRUM.

Gelatine Negative No. 148. Miller Bros. 21-2 huh.

LXXXVIII

ANOLIUS CAROLINENSIS.

TRANSVERSE VERTICAL SECTION THROUGH THE
MIDDLE OF THE CEREBRUM.

Gelatine Negative No. I4g. Grunow 2 Inch.

LXXXIX.

NERODIA FASCIATA.

TRANSVERSE VERTICAL SECTION THROUGH THE

MIDDLE OF THE CEREBRUM.

Gelatine Negative No. 8g. Miller Bros. 21-2 Iruh.

%^

.■RS-Wrtltey,,^

'i^!^!^'-

XC.

CISTUDA CAROLINA.

TRANSVERSE VERTICAL SECTION THROUGH THE

MIDDLE OF THE CEREBRUM.

Gelatine Negative No. ijo. Miller Bros. 2 1-2 Ineh.

■i

\^

\

\i

%,■

'■'■p^M^-:

©

XCI.

RANA PIPIENS.

TRANSVERSE VERTICAL SECTION THROUGH THE
MIDDLE OF THE CEREBRUM.

Gelatine Negative No. 151. Miller Bros. 2 1-2 Inch.

/■

/
y' ^ff

"' >i^

^

i €:, '

"■"'-^■' ,b.^ilsttig^''

XCII.

RANA PIPIENS.

TRANSVERSE VERTICAL SECTION THROUGH THE

POSTERIOR PART OF THE CEREBRUM.

FIBRES CONNECTING THE CORPORA STRIATA.

THIRD VENTRICLE BELOW.

Gelatine Negative No. 152. Grunow 2 Inch.

■■■M

'■■■'■■ ■■■'-■iy.'.'W >'i;>.*(y

I - I * „.-<r

9

XCIII.

RANA PIPIENS.

STRUCTURE OF THE CORPUS STRIATUM.

FROM A TRANSVERSE VERTICAL SECTION

THROUGH THE POSTERIOR PART OF THE CEREBRUM.

Gelalinc Negative No. /jj. Miller Bros. i-2 Inch.

.#n!^

«-'^

f ■

^ a^'

♦ *•

* ' ■■*' • > «i

^ .. '* .-^

./■

#

XCIV.

RANA PIPIENS.

STRUCTURE OF THE CORPUS STRIATUM.
FROM THE SAME SECTION AS THAT SHOWN IN PL. XCIII.
Gelatine Negative No. 154. Nachet 7 Immersion.

'3 'r:;?>*W-^f^V.' ...-'"■

,^^---:«

^a&i: >'-.

V:

'■'■Mm

fi-MiM^f^'--- - .■'■■Mm

'■^^^r,

xcv.

RANA PIPIENS.

TRANSVERSE VERTICAL SECTION THROUGH THE

OLFACTORY LOBES. OLFACTORY ENLARGEMENTS BELOW.

Gelatine Negative No. loj. Miller Bros, i 1-2 Inch.

XCVI.

MENOPOMA ALLEGHENIENSE.

TRANSVERSE VERTICAL SECTION THROUGH THE

MIDDLE OF THE CEREBRUM.

Gelatine Negative No. i86. Miller Bros. 21-2 huh.

XCVII.

SIREN LACERTINA. CEREBRAL LOBE.

VERTICAL TRANSVERSE SECTION.

Gelatine Negative No. 17S. Grunow 2 Inch.

L

in

■f-

0)

//i^S'

i

3 '--il

^•^ "»5,.i?'''--:i^'>-- "W, ,;-.o-;. -r ■ b•--''r-"'::C^'^.^f1^-..-

XCVIII.

DIEMYCTYLUS TOROSUS. CEREBRUM.

FRAGMENT FROM A TRANSVERSE VERTICAL SECTION.
Gelatine Negative No. ij6. Miller Bros. i-2 Inch.

^®^

v

*H^Z-.^

<3 » >

t\»* •^.^'

XCIX.

ALLIGATOR MISSISSIPIENSIS. SPINAL CORD.

TRANSVERSE SECTION THROUGH THE MIDDLE OF THE
LUMBAR ENLARGEMENT. NUCLEI IN THE NERVE
• CELLS OF THE INFERIOR (ANTERIOR) HORN.
Gelaiuie Negative No. ij2. Aliller Bros. 1-2 Inch.

...«.MJW"^"*?"!^>

£m

s=f :-

-'*>

\:'^J'.'

^>^

J5^'' •> >^.' , '>^ ■ . <iH,,si' " '■■'^ •■■ ■•:w^ V.'--

•xV.'

SA- ->:

' "'-iL- .

^•^'V^^

®^2;-

•■ % '

' ' ... ^ ■ ■ *

' . ' V '^■

- ' - ;:..'*"

■ ■-%'

■"^ ■ . . ' ..

•' - ■ '" * t

■■ p',.. ■■'.^■'

•■|, ' . ■ '.r ,■"'

■'' "■■..'".■■ "^

,1 - •.*

■■' :^'^^-I

i- ''. " ' -.

.. . ■ . . ^-'y '■,' ■

mm-

... ■ '■ V v."

' :. .? ^'

,.>....,' 'r.^^sPS^-.'"'^-"

c.

ALLIGATOR MISSISSIPIENSIS.

TRANSVERSE SECTION THROUGH THE CELLS OF ORIGIN

OF A MOTOR ROOT OF THE TRIGEMINUS.

Gelaii7ie Negative No. IJ3. Miller Bros, i Inch.

CI,

ALLIGATOR MISSISSIPIENSIS.

NUCLEI IN THE NERVE CELLS OF ORIGIN OF THE

OCULOMOTORIUS.

Gelatine Negative No. 74. Gruiww 4-10 Inch.

V

CII,

ALLIGATOR MISSISSIPIENSIS.

NUCLEI IN THE NERVE CELLS OF ORIGIN OF THE
MOTOR ROOT OF THE TRIGEMINUS.

Gelatine Negative No. 4g. Grwno 4-10 Inch.

^ift^#t

*.'

V ■

'.',-^><«t:'>>Vl,

•^:-^?S

•.■:■■(' ::iMii^i!^;

cm.

ALLIGATOR MISSISSIPIENSIS.

NUCLEI IN THE NERVE CELLS OF THE RAPHE.
Gelatine Negative No. jo. Gruiiow 4-10 Inch.

vf**

/^ Jt

fl i' /<?

''' .# ^v ^

\

CIV.

ALLIGATOR MISSISSIPIENSIS.

NUCLEI IN THE CELLS OF AN EMINENTIA ACOUSTICA.
Gelatine Negative No. jp. Grwunv 4-10 huh.

•--)

».<iK^''*-

4P

: .- -i^ -f^' - "^ «^]'

»r. ,

rV'

;■//■.-.

.^ ^1

<•->

<f,t^mm^^¥^^f^^'l^mf

y,r\

v-isSV

CV.

TESTUDO POLYPHEMUS.

NUCLEI IN THE "ROOF" OF THE OPTIC LOBES.
Gelatine Negative No. 1J7. Grutiow 1-5 Inch.

CVI

TESTUDO POLYPHEMUS.

NUCLEI IN THE CELLS OF ORIGIN OF THE
ABDUCENS.

Gelaline Negative No. J I. Grimmv 1-5 Inch.

evil.

TESTUDO POLYPHEMUS.

NUCLEI IN THE CELLS OF ORIGIN OF THE

MOTOR ROOT OF THE TRIGEMINUS.

Gelatine Negative No. yo. Grimow 1-5 Inch.

■■J*.

■ .TT^J"!"

t-

- ■■>•::

.*'.-

CVIII.

TESTUDO POLYPHEMUS.

NUCLEI IN THE CELLS OF ORIGIN OF THE
SPINAL NERVES. CERVICAL ENLARGEMENT.

Gelatine Negative No. 68. Grunow /-j Inch.

CIX.

TESTUDO POLYPHEMUS.

NUCLEI IN THE CELLS OF ORIGIN OF THE

SPINAL NERVES. LUMBAR ENLARGEMENT.

Gelatine Negative No. <5p. Gruncnu /-j Inch.

£*f

V

-i*^

'"■•*

'■"i^.

'

-^* ^

f -^

•v^

•^ t

ij.

r r

V

^^ SS>

^ i

**■»

it. 1 ^

ex.

CHELYDRA SERPENTINA.
NUCLEI IN THE CELLS OF ORIGIN OF THE

OCULOMOTORIUS.
Gelatine Negative No. 158. Miller Bros. 1-2 Inch.

.^

i^

K^fe'Ai'^.i^.'il

r '^

CXI,

CHELYDxRA SERPENTINA.

NUCLEI IN THE CELLS OF ORIGIN OF THE

MOTOR ROOT OF THE TRIGEMINUS.

Gelatine Negative No. 121. ■ Miller Bros. 1-2 Inch.

.^•. ■:.'■■ t

*®^;.-^>

:rm^^'

' ^^^_

II

■ JO ■ .. 2-.' i^ iO"^:-^:^.-'.^" '-;.■■ • • V-' . -. •: ' - ■ ^r --^ - v-\^raBt

CXI

RANA PIPIEN3.
NUCLEI IN THE NERVE CELLS FROM VARIOUS GANGLIA.

I SPINAL CORD. BRACHIAL ENLARGEMENT.

II " " CRURAL

HI MOTOR ROOT OF THE TRIGEMINUS.
IV OCULOMOTORIUS.

Gelatine Negatives. Nos. Sj-S6. Grunmu i-j Inch.

•^,/

CXIII.

PHRYNOSOMA CORNUTUM.

NUCLEI IN THE CELLS OF ORIGIN OF THE

OCULOMOTORIUS.
Gelatine Negative No. itp6. Miller Bros. 1-2 Inch.