59.51.21 : 14.8.

CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY Or I 'IE

MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD

COLLEGE. E. L. MARK, DIRECTOR.

TH1: NERVOUS SYSTEM OF TUT; OKSTODE
MONE/UA EXPANSA.

UC-NRLF

B 3 3bO TSfi

5v WILLIAM L TOWKU.

TTTH S PLATKS.

REPRINTED FROM ZOOU>GISCHK JAHp.ui:CHK' . AP.TH. F. ANAT. u. ONTOG.
BAND XIII. J'FKI 3.

CAMBRIDGE, MA«S., U.S.A.

GIFT OF

William L Tov/er

*7 A o T

BIOLOGY

RA
6

/

Nachdruck verboten.
Uebersetzungsrecht vorbehalten.

The Nervous System in the Cestode Moniezia expansa.

Wm. L. Tower.

With Plates 21—26.

Contents.

Introduction.

I. Material and Methods.

A. Material.

B. Methods.

1. Media for Collecting and

2. Keeping Cestodes alive in the Laboratory.

3. Methods of Fixing and Staining the Nervous tissues.
II. Description of the Nervous System.

1. In the Scolex.

2. In the Neck Region.

3. In the Mature Proglottides.
Papers cited.

Explanation of Plates.

Introduction.

The work of which this is an account was done during the winter
of 1895—96. A preliminary paper was published in the Zoologischer
Anzeiger, July 20, 1896. It was my intention at that time to follow
the preliminary paper with a final one as soon as it could be pre-
pared, but ill- heath and other circumstances over which I have had
no control have delayed its preparation much longer than I expected.

When this work was begun the knowledge of the nervous system
in Cestodes was in a very unsatisfactory condition. The anatomy,
and, to some extent, the histology of these forms, exclusive of the
nervous system, were fairly well known. Considering the valuable

Zool. Jahrb. X11L Abth. f. Morph. 24

36Q './ : :/: • • WM. L. TOWER,

i^jjlte Jobfajfeecl 3by many authors in using the chrome-osmium-silver
method blf UOLGI and the methylen-blue method in neurological studies
on other animals, and the interesting character of these worms, it is
rather surprising that the condition of the nervous system should
have been incompletely determined. Some explanation of this may
be found, however, in the seemingly indifferent action of the chrome-
osmium-silver method upon Invertebrates in general; in the transient
character of methylen-blue impregnations; in the loose arrangement,
the non-medullated character, and the small size of the nerve fibres
of Cestodes, which render ordinary stains useless; and in the con-
sequently almost total failure of the best nerve methods when applied
to these parasites. All these conditions combine to make the study
of the nervous system in Cestodes very difficult.

From the time of NIEMIEC'S (1885) paper until that of BLOCH-
MANN (1895) little or nothing had been discovered on this subject.
Previous to the appearance of BLOCHMANN'S paper the nervous system
of the Taenias had been known to consist of a system of ganglia,
commissures, and connectives in the scolex, more or less complex,
according to the species, as described by NIEMIEC (1885); one large
and one or two accessory lateral nerve trunks, lying external to the
longitudinal excretory tube; and two dorsal and two ventral nerves
that could not be traced beyond the neck region. Occasional branch-
ings of these nerves in the proglottides had been recorded by various
authors, but the course of these branches, and the existence of ganglionic
cells had not been clearly demonstrated in any form until within the
past two years. The papers of BLOCHMANN, ZERNECKE, LUHE and
COHN, a note by KOHLER and one by myself all confirm the existence
of a constant, definite and extensive system of ganglia, commissures,
and connectives, a wealth of ganglionic cells, and the existence of
nerve terminations in the periphery of the animal that would seem to
indicate for them a sensory function.

These results have been obtained by the use of three methods:
that of GOLGI, the methylen-blue intra-vitam stain , and the proper
use of VOM RATH'S fluid. In my work I have been only slightly
successful with methylen-blue, and wholly unsuccessful with GOLGI'S
method; but by the careful manipulation of the material in VOM
RATH'S fluid, followed by crude pyroligneous acid, very desirable results
have been obtained. Many other methods have been tried, but without
success.

Another and rather difficult problem constantly confronted me

The nervous system in the Cestode Moniezia expansa. 361

during the progress of my study - that of keeping the- wonns vaftve
and constantly at hand for use in the laboratory. $lth0ugh material
was abundant at the abattoir, it required considerable time 'and trouble
to obtain it, and when working with methylen-blue it was absolutely
necessary to have a constant supply of living material. As the
methods given by LONNBERG for this purpose were a failure, as far
as this species was concerned, considerable time was spent in ex-
perimenting with different mixtures and methods for keeping the
worms alive.

I. Material and Methods.

A. Material.

Abundant material from the small intestine of Ovis aries was
obtained as needed from the abattoirs of Boston. The cestodes
Moniezia expansa were taken from the intestines shortly after the
animals were slaughtered and before the viscera became cooled. It
was found best to visit the abattoir early in the morning soon after
work had commenced, as one was then sure of being able to examine
the viscera before they became cool, or had suffered from lying in
heaps in the "gut room", or from the rough handling which often
destroys the larger and more desirable specimens.

In removing the worms it was found undesirable to slit open the
intestine, but much better to sever it near the beginning of the coecum,
then, beginning at the pylorus, slowly to "strip" the intestine between
the thumb and forefinger, causing the contents to flow from the cut
end. In parasitized animals the greater number of worms were found
in the ilium, or caudal portion of the intestine, a few in the jejunum,
and only occasionally one in the duodenal region. Although this
method of removing the worms was not all pleasant, it was rapid and
practical. Moreover, by this method, the worms could be removed
not only in a more satisfactory and less broken condition, but more
easily and rapidly, and without exposing them to the air as long as
in the process of opening the intestine longitudinally. In almost every
case where the worms were removed in this manner the scolex came
away with the proglottides. Moreover, the scolex was not injured in
any way by this treatment, as the worms evidently relax their hold
upon the intestinal wall; whereas, if the intestine was slit open and
the worms taken out, they invariably held tightly to the wall, and
could be removed only by being pulled or cut away. This resulted

24*

362 WM. L. TOWER,

in 'distorting^ 'and often tearing the scolex to such an extent as to
: /• Oeetidaij Jit • unfit 'v*for use. Each parasitized animal usually contained
' from fw6"*tb 'fifteen worms, each from 50 cm to 200 cm in length,
and I have occasionally taken more than fifty (once 58) good-sized
worms from one host.

B. Methods.

1. Media for Collection and Transportation.

The worms were quickly separated from the contents of the in-
testines by the fingers, not with forceps, and placed in one of several
media for transportation to the laboratory. For this purpose physio-
logical salt solution (0,75 %) was first used. This was tried at various
temperatures, from 10° C to 30° C, but was found to be uniformly
harmful, as it produced stupefaction and rapid death, accompanied by
a more or less marked plasmolysis. Distilled water, faucet water,
and distilled water with sodium chloride in varying percents (1 % to
6,5%) were in tne lower grades accompanied by strong plasmolysis,
while the higher percents acted as an irritating stimulant, producing
distortions and death. If the material was afterwards to be treated
with VOM RATH'S mixture, the physiological salt solution gave fair
results, provided the worms were placed in his mixture as soon as
the laboratory was reached. It was positively harmful, however, to
allow the worms to remain in this solution more than one hour; for,
even after only an hours exposure, VOM RATH'S method was rather
ineffective, as far as the demonstration of the nerves was concerned.
It would have been more desirable to have placed the worms in the
killing fluid at the abattoir; but, as all foreign substances had to be
removed before killing, and this could not be done at the abattoir, it
was necessary to defer the killing until they had been taken to the
laboratory.

A mixture produced by adding one percent of pepsin to normal
salt solution gave better results, as the reaction upon the worms was
not as pronounced as that shown by the physiological salt solution.
With material collected in this mixture, as also with that in the
simple salt solution, I was unable to obtain a satisfactory intra-vitam
stain by the methylen-blue method or a satisfactory GOLGI impregnation,
although methylen-blue was found to stain to some extent. If the
amount of sodium chloride was decreased and that of pepsin increased
to the following proportions,

The nervous system in the Cestode Moniezia ezpansa. 363

hydrant water .... 100,0 ccm

sodium chloride . . . 0,5 g

pepsin . ..;..•„ > 1,5 g

the results were still more satisfactory; but even with material col-
lected in this mixture neither GOLGI impregnations nor methylen-blue
stains were obtained. When killed in VOM RATH'S mixture material
collected in this fluid gave very good results ; but the best fluid found
for the transportation of the worms contained no sodium chloride.
It was composed of

hydrant water .... 100 ccm

pepsin 2 g

egg albumen (fresh) 10 to 15 g

Worms placed in this mixture appeared to suffer no harm even if left for
several hours provided the temperature did not go delow 10° C nor
above 30° C. With worms collected in this fluid a fair methylen-
blue intra-vitam stain was obtained, but, as my work was nearly at
an end before this solution was tried, I have not been able to test
it fully.

For all ordinary purposes, preparatory to killing in the more
common reagents, I believe the worms could be collected in the
physiological salt solution without any appreciable change either in
cell arrangement or cell contents; but for the study of nerves the
material should not be placed in physiological salt solution, nor in
any solution containing sodium chloride.

2. Keeping Cestodes Alive in the Laboratory.

When the laboratory was reached the material was first washed
or rinsed in the fluid in which it was collected, or in a fresh supply
of the same, until it was free from all dirt and chyme. It was then
placed in a fresh, clean portion of the fluid, and finally in from
20 to 30 minutes after being taken from the animal, the worms were
ready for the killing reagents.

In many cases it was found desirable to keep the worms alive
for a greater or less length of time, especially when the methylen-
blue process was employed. Attempts to keep the worms in any
mixture containing salt were fruitless, as they could not thus be made
to live more than a few hours at most. Distilled water and hydrant
water were both equally worthless, but after considerable experimenting
and many failures the following mixture was compounded, in which,

364 WM. L. TOWER,

with proper care, it was possible to keep the worms alive for 2,
3 or 4, and sometimes even for 5 days:

hydrant water .... 100 ccm

egg albumen (fresh) . . 10 g

pepsin 2 g

cane sugar 2 g

.prepared beef (Bo vox) . . 5 g

The worms, only one or two in a dish, were placed in this mixture
freshly made, of which 100 ccm was allowed to each worm. They
were kept in the laboratory in the dark, no attention being paid to
temperature, for it was found that the temperature between certain
limits (10° C to 30° C) was not a very important factor, although
about 17 ° C seemed to be the most favorable. Every morning the
worms were placed in a freshly made mixture, care being taken to
clean thoroughly the dishes before the fresh culture-solution was put
into them. I was unable to use successfully the methods given by
L.ONNBERG (1892) for keeping Cestodes alive in the laboratory.

3. Methods of Fixing and Staining the Nervous Tissues.

The chrome-osmium-silver methods of GOLGI, both the slow and
the rapid, with various modifications proposed by recent writers were
the ones chiefly tried, but always without success. I was unable to
determine the cause of failure. In nearly all cases there was, however,
a good impregnatiou of the dorso-ventral, longitudinal, and transverse
muscle fibres. The plan proposed by STRONG (1895) of using formic
aldehyde in place of osmic acid was also unsuccessful, although this
combination gave good results for other Invertebrates (e. g. Echino-
rhynchus), used in check experiments.

Various modifications of the gold-chloride methods were not more
successful than the GOLGI methods.

With the axis-cylinder stains the results were likewise unsatis-
factory, although better than with the GOLGI and gold-chloride methods.
The method of NISSL (1886) gave a good stain of the lateral nerve,
and by its use many of the other nerves could be traced after one
had learned where to look for them ; but this stain did not differentiate
nervous tissue from muscular and connective tissue. The method of
ALT (1892) was useless for my purpose. REHM'S (1892) method
was also unsatisfactory in that it did not separate nervous from
muscular and connective tissue. WOLTER'S method was the most
satisfactory for staining the axis cylinder, but it did not dif-

The nervous system in the Cestode Moniezia expansa. 365

ferentiate nerve tissues from the other tissues as well as VOM RATH'S
method.

Throughout the most of my work material was used that had
been subjected to sodium chloride solutions, but finally the solution
described on page 363 was tried and gave good results. Unfortunately
the opportunity was wanting for continuing the work with this more
favorable material. The method which at the last was found best
adapted to Moniezia was as follows: The material collected at the
abattoir was placed in the solution the formula for which is given on
page 363, and was thus carried to the laboratory. It was there
washed and the worms not required at once were placed in the culture
solution described above (page 364). Those which were to be treated
immediately were cut into pieces consisting of two or three pro-
glottides each, dried for a moment on filter paper, and placed in a
clean watch glass. The pieces were then covered with a freshly made
mixture composed of 60 and 40 volumes respectively of the following
solutions, A and B:

A. methylen-blue (dry) v; 1 g
hydrant water . . . 1000 ccm

B. egg albumen (fresh) . 60 g
hydrant water ... 40 ccm

Only enough of this mixture was used to cover the specimens, a little
being added from time to time to replace that lost by evaporation.
It seemed best to keep the specimens exposed to the air and at a
rather low temperature (3 ° C to 8 ° C). After being stained from half
an hour to two hours, according to conditions, the material was placed
for 20 or 30 minutes in the following freshly made mixture:
ammonium molybdate . . 10 ccm
hydrogen peroxide . »;<v.r 2 ccm
hydrochloric acid (strong) . 6 drops

The object in the use of this mixture was to fix the stain in the
nervous tissues and to wash it out of all others ; but its action in the
present case shows that this result does not always follow. The
tissues were removed from the mixture as soon as they became
greenish, the washing out having by that time gone far enough. This
took on an average about half an hour, but the time varied with dif-
ferent specimens. It was best to keep the mixture containing the
objects at a low temperature, near 0° C. This solution was then
gradually replaced by adding slowly a 1 °/0 solution of osmic acid until
the ammonium molybdate solution was replaced by a 1 % solution of

366 WM. L. TOWER,

osmic acid. The tissue was allowed to remain in 1 % osmic acid
until it became brownish; it was then removed, washed in 50% al-
cohol, and put into 70% alcohol for twelve hours. After being
dehydrated it was imbedded in paraffine, xylol instead of chloroform
being used as a solvent. Better preparations were obtained, however,
if the thoroughly hardened material were cut free-hand in liver or
pith, cleared in xylol, and mounted in balsam.

None of the preparations made by this method, whether imbedded
in paraffin or cut free-hand, kept well. Those that were good in
June 1896 were of no value a year later, although they had been
kept most of the time in the dark, and had never been long exposed
to strong light.

Trials with the methylen-blue method did not turn out very suc-
cessfully until near the end of my work. I was able, however, to get
some impregnations, which, though in themselves of little use, were
of considerable value when taken in connection with the results ob-
tained by the use of VOM RATH'S method.

It was with VOM RATH'S method that the most satisfactory
results were obtained. Although this method does not allow of the
isolation of the individual nerve elements, or neurons, it is admirable
for tracing nerves, even when they are small and contain but a few
fibres. Preparations made by this method are clear and well-defined,
although not diagrammatically so, like GOLGI and methylen-blue pre-
parations. They also show the histological structure of ganglionic
cells better than either of the former.

By this method fair results were obtained even when special
care had not been taken in collecting the material, but the best
results were those from material collected in the solution described
on page 363. A fair staining of Moniezia material was also secured
with VOM RATH'S mixture when the worms had been collected in a
2% solution of formaldehyde. Material left in this solution 35
days before being placed in VOM RATH'S fluid gave very fair results.
In this case the stain was darker than when fresh material was used,
but not too dark to be of considerable value. It is probable that
care in regulating the exposure of such material to the action of
VOM RATH'S mixture would give a lighter and more desirable stain.

In using VOM RATH'S method fresh material was put into the
following VOM RATH'S mixture:

sat. aq. sol. picric acid, filtered . . 500 ccm
glacial acetic acid _,.ftj , 3 ccm

The nervous system in the Cestode Moniezia expansa.

platinic chloride (in 5 ccm dist. H2O) . 5 g

osmic acid crystals 2 g

After having remained in this mixture for ten hours the worms were
removed and cut into pieces from 1 to 3 cm in length. These
were put first into crude pyroligneous acid for from 6 to 10 hours,
and then into 70 % alcohol for 24 hours. After being dehydrated and
inbedded in paraffine they were cut into sections 62/3 ^ thick. This
method gave preparations in which the nerves were colored grayish
blue, the more highly refractive muscles brown, and the connective
tissue pale gray or steel blue.

n. Description of the Nervous System.

A fresh adult specimen of Moniezia expansa is commonly about
1 m in length, and from 10 to 15 mm broad at the posterior end.
In such an animal there are between 500 and 1000 proglottides. The
scolex is on an average 1 mm in diameter and 2 mm in length,
measured from the anterior end to a point just posterior to the
cephalic ganglion; but the dimensions of the scolex vary considerably
in different animals. There are neither rostrum nor hooks in this form.
There are two sets of sexual organs in each proglottis, opening one
on either margin of the proglottis in a gonopore. The musculature is
well developed and is similar to that found in other Taenias.

The anterior part of the excretory system in the scolex of Mo-
niezia expansa consists of a horseshoe-shaped tube the curved end of
which is situated at about the level of the anterior nerve ring. It
lies in the frontal plane and is divided symmetrically by the sagittal
plane. Each of the arms of this tube fork, giving rise to branches
that pass respectively dorsal and ventral of the cephalic ganglia
(PL 21, Fig. 1). These branches have been designated as the dextro-
dorsal, va. dx-d; the dextro- ventral, va.dx-v\ the sinistro-dorsal, va.s-d,
and the sinistro- ventral longitudinal excretory tubes (PI. 21, Figs. 1,
5 and 6). These four tubes bend slightly outward (PL 21, Fig. 1),
passing close to the surface of the cephalic ganglia, opposite which
they turn sharply outward and forward; but, after continuing for a
short distance in this direction, they turn backward through an angle
of more than 90 °, and run parallel to one another and to the lateral
nerve. These four excretory tubes pass backward through the neck
region into the younger proglottides, the dorsal pair becoming larger
and occupying the position of the longitudinal excretory tubes of the

368 WM. L. TOWER,

mature proglottides , while the ventral pair becomes smaller and is
lost in the older proglottides.

The nervous system of Monieeia is imbedded in the connective
tissue of the body without any definite bounding membrane or
continuous protective structure. Many of the larger and more im-
portant trunks, however, have along their courses cells (cl.viri) of a
peculiar character. They are elliptical, about twice as long and half
as thick as they are broad, and from each cell there are given off a
number of branching processes that run over the surface of the nerve.
I believe that these processes serve to bind the nerve elements into
a firmer structure, though they are not very close together, and do
not form a continuous covering. These ("binding cells") are shown in
PL 24, Figs. 15 and 16; PL 25, Figs. 29 and 30, and are somewhat
different from the Hiillzellen described by ZERNECKE (1895, p. 137) from
Ligula. They occur upon the nerves of the scolex and upon the large
lateral nerve trunks. I have not yet found them upon the other nerves.

1. In the Scolex.

The nervous apparatus of the scolex consists of 1) the anterior
nerve ring with its four ganglia ; 2) the pair of large cephalic ganglia ;
3) the connecting bundles of nerves between 1 and 2 and 4) the dorsal
and ventral commissures connecting the outer ends of the cephalic
ganglia.

At about one-fifth of the length of the scolex from its anterior
end is found that part of the central nervous system which I have
called the anterior nerve ring (n.a, PL 21, Fig. 1). The ring contains
four ganglia, one in each of the four quadrants formed by the
intersection of the sagittal and lateral planes of the scolex, and a
little in front of and deeper than the corresponding acetabulum.
These ganglia are here designated according to their positions as the
anterior dextro-dorsal (gn.a.dx~d, PL 21, Fig. 1), sinistro-dorsal
(gn.a.s-d), dextro-ventral and sinistro- ventral ganglia. The bundles
of nerve fibres connecting the ganglia with one another constitute the
anterior nerve ring. The ganglia contain a moderate number of
ganglionic cells, which differ from those of the rest of the nervous
system in size. They are small and, I believe, mostly unipolar,
although there are a few bipolar and multipolar ones. These cells
(PL 24, Figs. 21—24, 26) have a clear and relatively large nucleus, with
a deeply staining nucleolus; but no trace of a chromatin network or
granular structure was observable in the nucleoplasm. The nuclear

The nervous system in the Cestode Moniezia expansa. 369

membrane is very thin, often almost indistinguishable from the
granular cytoplasm that surrounds the nucleus, but it is not of uniform
thickness, small thickenings appearing without regular arrangement
upon its inner surface. The cytoplasmic contents are gathered about
the nucleus into a dense granular mass, from which threads and films
of spongioplasm radiate through the hyaloplasm to the cell wall, thus
producing more or less of a stellate appearance (PI. 24, Figs. 2 1—24,26).
From these anterior ganglia are given off nerve fibres that are distri-
buted to the anterior end of the scolex, to the acetabula, and to the
musculature of that region. I was not able to discover any regularity
in the number or distribution of these branches, such as NIEMIEC (1885)
has shown; there was instead a very loose, poorly defined, set of
nerves that crossed and recrossed one another in a very confusing
manner.

NIEMIEC (1885) has described in Taenia coenurus a nerve ring
lying anterior to the acetabula, but having eight ganglia -- instead
of four, as in Moniezia - - placed in pairs, one pair in each quadrant
of the scolex. In Taenia serrata he also found an anterior nerve
ring, but without any pronounced ganglionic enlargements.

In Moniezia expansa, as in Taenia coenurus, there are eight
distinct longitudinal nerve trunks that pass backward from the anterior
nerve ring, two arising in each quadrant of the ring, but unlike Taenia
coenurus these large pairs of nerve trunks have their origin in the
posterior surface of each of the four anterior ganglia, one on the ex-
ternal edge of the ganglion, the other on its internal edge. The one
arising on the inner edge which is the larger, passes to the cephalic
ganglion of its own side, and in passing backward approaches
toward the chief axis of the worm ; while the one that arises from
the outer edge runs posteriorly parallel to the surface, becoming
either one of the two dorsal or two ventral longitudinal nerves. (The
further description of these outer nerves will be taken up after an
account of the inner nerves and of the position of the nervous apparatus
immediately connected with them.)

The two inner nerves arising from the ganglia of the right side
of the animal converge until they meet at a point not far behind the
division of the excretory tube into its dorsal and ventral branches,
where they at the same time unite with the right anterior horn of
the cephalic ganglion (PL 21, Figs. 1 and 2). The nerves of the left
side have similar relations. These nerves may be called the cephalic
connectives, being simply compact bundles of nerve fibres without

370 WM. L. TOWER,

ganglionic cells or any of the protecting or "binding" cells charac-
teristic of other portions of the nervous system. They do not give
off branches in any part of their entire length, but are simply con-
nectives between the anterior ganglia and the main portion of the
central nervous system - - the pair of large cephalic ganglia.

The large cephalic ganglia are situated in the posterior part of
the scolex, a little behind the acetabula, one on each side of the
sagittal plane. Each of these cephalic ganglia consists of a large
rounded mass or body (compare PI. 21, Figs. 1 and 5, and PL 22,
Fig. 8) with a fairly smooth even surface and two projections or
horns. The anterior median side of each is prolonged anteriorally
into a conical process, the anterior horn (PI. 22, Fig. 8 conu. a), which
receives the fibres of the cephalic connectives of its own side. The
lateral portion of each ganglion is also prolonged into a cone-shaped
structure, the external horn (conu. ex), which contains the fibres of
the lateral nerve. The two ganglia are connected with each other
by a relatively small commissure (PL 22, Fig. 8 corns), the fissure
between the ganglia in the median plane being deep, especially in
front and behind.

The body of the cephalic ganglion is made up of a core of
ganglionic cells traversed by nerve fibres and a cortical portion com-
posed almost entirely of fibres, the whole being enveloped in the
richly branched "binding" cells. The ganglionic cells are not as large
as those in the ganglia of the proglottides , but they are like them
in every other respect. Many of them are multipolar, and are often
richly supplied with branching processes (PL 24, Fig. 18). The nuclei
are relatively large, spherical, hyaline, with a deeply staining nucleolus
but no chromatic network ; the nuclear membrane is thin, has irregular,
thickened places, and in some instances a shrunken appearance, very
much like that found by HODGE (1892) in the spinal ganglia of Verte-
brates after a day's exercise, or after artificial stimulation. In the
cell shown in PL 24, Fig. 18 the dendritic or protoplasmic processes
are very numerous, but in VOM RATH preparations they are not easily
followed. Some of the nerve processes of such ganglionic cells have
deeply staining thickenings occurring at about equal intervals, as
may be seen in some of the processes of Fig. 18. Bipolar cells are
much more common than those of the unipolar type, and occasionally
there is found a peculiar form (PL 24, Fig. 19), which might readily
be taken for a unipolar cell, but which is in reality bipolar. The
cytoplasmic contents of these cells have the same stellate arrangement

The nervous system in the Cestode Moniezia expansa. 37 ^

as in the other ganglionic cells of this animal. Where the nerve fibre
joins the cell there is an accumulation of granules similar to that
about the nucleus (PL 24, Fig. 18). The anterior and external horns
of the cephalic ganglia have but few ganglionic cells, being for the
most part composed of nerve fibres.

Although I am not yet prepared to give a detailed account of
the path taken by the nerve fibres through the cephalic ganglion, I
have to some extent followed their courses and give what I believe
to be the paths of the principal groups of them. There is a large
bundle of fibres (PI. 22, Fig. 8 B\ which seems to arise from the
central ganglionic mass of either side, and to pass through the posterior
part of the transverse commissure into the ganglion of the opposite
side. The bundle here traverses the posterior part of the ganglion,
curving around behind the ganglionic core, and emerges through the
external horn to enter the lateral nerve of the side opposite that in
which it arose. This bundle is joined just before it passes through
the transverse commissure, by a smaller bundle (PL 22, Fig. 8 D),
which enters the cephalic ganglion through its anterior horn, probably
arising from the two "anterior ganglia" of the same side of the scolex.
A third bundle of fibres arising from the anterior ganglia of each
side enters the cephalic ganglion of the same side through its anterior
horn, passes along the anterior border of this ganglion near its sur-
face and finally emerges through its external horn to enter the lateral
nerve of the same side of the scolex in which it originated. There
are also several other smaller distinct bundles of nerve fibres in the
body of the cephalic ganglia, the most conspicuous one being a bundle
that traverses the anterior part of the transverse commissure con-
necting the central ganglionic cells of one cephalic ganglion with
those of the other.

The external horn of the cephalic ganglion is enlarged where it
joins the lateral nerve, and from this enlargement arise several small
nerves that are distributed to the acetabula and to the muscles that
operate them. From this enlargement there also arise two broad
bands of nervous tissue, one from its dorsal, the other from its
ventral surface. The former passes dorsad of the dorsal excretory
tubes, the latter ventrad of the ventral excretory tubes, to enter the
corresponding regions of the cephalic ganglion of the opposite side
of the body. These are respectively the dorsal and ventral cephalic
commissures (PL 21, Figs. 1 and 5 corns, d', corns, v'). These com-
missures are thin bands of loosely arranged nerve fibres, which in

372 WM. L. TOWER,

their course meet the two dorsal and two ventral longitudinal nerves.
Not only do fibres of these bands decussate with those of the longi-
tudinal nerves, but fibres also pass from commissure to longitudinal
nerve and vice versa. Along the course of these commissures there are
found a few ganglionic cells which are mostly of the unipolar type (PL 22,
Fig. 11). The position and appearance of these commissures reminds
one of the two hexagonal commissures found by NIEMIEG (1885) in
Taenia coenurus and T. serrala, with one of which they are pro-
bably homologous, although apparently they are less well defined
nerves than those in the species studied by NIEMIEC.

Returning to the four outer nerves arising from the anterior
ganglia, it is found that in running backward they approach one
another slightly and that each passes through the dorsal or ventral
cephalic commissure, from which a few nerve fibres are received.
Behind the cephalic commissure they run nearly parallel with one
another, becoming the dextro-dorsal, sin istro- dorsal, dextro-ventral
and sinistro-ventral longitudinal nerves (PI. 21, Figs. 1, 2, 4 and 5).
In the scolex these are simple, rather compact bundles of nerves,
without ganglionic or ubinding" cells; but in passing backward
ganglionic cells begin to appear in the neck region. At first these
are few, but as older proglottides are reached the number increases.
These nerves correspond exactly in origin, position and the course
taken with those described by NIEMIEC (1885) in Taenia coenurus
and T. serrata. NIEMIEC was unable to trace them beyond the neck
region, but I have found them in proglottides taken from all parts
of the worm, and always occupying the same relative position in the
proglottis. Although I have not traced them continuously from pro-
glottis to proglottis through an entire strobila, I think that their occur-
rence in the same relative position in proglottides taken at random
in the same animal is evidence enough that they are continuous
throughout the entire length of the worm.

2. In the Neck Region.

In the neck region of Monieza the most prominent nerves are
the six longitudinal ones. The two large lateral nerves arising from
the external horns of the cephalic ganglia lie in the usual position
external to the longitudinal excretory tube. They are single nerve
trunks nearly circular in cross-section, and not sharply defined in
outline. I have not succeeded in finding in Moniesia the two ac-
cessory lateral nerves which are described for other forms by NIEMIEC,

The nervous system in the Cestode Moniezia expansa. 373

and COHN, as accompanying each of the lateral nerve trunks.
For the first 5 mm behind the scolex the lateral nerves are of uni-
form diameter, they possess only a few ganglionic cells and no trace
of ganglionic enlargements. The "binding" cells enveloping them are
few, long tracts existing without any such elements. The branches
arising from the lateral nerves are mostly limited to the formation of
the dorsal and ventral commissures (PI. 21, Fig. 1).

The dorsal and ventral nerves are likewise without ganglionic
enlargements in the neck region, and the ganglionic cells are few. In
the posterior part of the neck region where the proglottides begin to
be distinguishable, the nerves begin to assume the condition which
they present in the mature segments. In this portion of the neck
region each lateral nerve begins to exhibit an enlargement at a point
near the posterior margin of the proglottis. This enlargement is due
to the increased number of ganglionic cells occurring in the nerve at
that point ; these increase in number continuously until the proglottis
is mature. The enlargement of the lateral nerve caused by this in-
crease in the number and size of the ganglionic cells is the first in-
dication of the posterior lateral ganglion (PL 21, Fig. 1 gn.l.p). The
position of these ganglia is indicated in the preceding portion of the
neck region by the presence of the small branches from the lateral
nerve which correspond in position to the posterior part of each young
proglottis. These branches are undoubtedly the beginnings of the
dorsal and ventral commissures of the mature segments which are
recognizable, then, before the ganglionic enlargements of the lateral
nerve with which they are connected.

At a distance of 30 mm from the scolex the posterior lateral
ganglia are well marked. In favorable sections from this region made
in a frontal plane it is possible to trace the individual neurons of
the lateral nerves (PL 26, Fig. 32). The ganglionic cells are usually
nearly triangular and of the unipolar type ; there are a great number
of dendritic, or protoplasmic, processes which interlace with those of
neighboring ganglionic cells. In the section shown in PL 26, Fig. 32,
there are three unipolar and two bipolar ganglionic cells, which, for
some reason, are more deeply stained than the others. At least two
kinds of neurons are distinguishable ; in one the ganglionic cell sends
a nerve fibre posteriorly from its ganglion to the next following one ;
in the other anteriorly to the preceding ganglion. A complete iso-
lated neuron is shown in PL 24, Fig. 25.

In each of the ganglionic enlargements there lie between the

374 WM. L. TOWER,

ganglionic cells others which do not appear to have any nerve fibre
connected with them. These cells are richly branched, the branches
interlacing with the dentritic processes of the ganglionic cells. It is
impossible to say whether they act as a means of connection between
different neurons, whether they are developing ganglionic cells, or have
some other function. One of these cells is shown very faintly in
PI. 26, Fig. 32. In this region the dorsal and ventral commissures
have become in so far complete that they can be traced from the
posterior lateral ganglion of one side to that of the other. The
ganglia of the dorsal and ventral nerves have also begun to be
distinguishable, but there is as yet no trace of the anterior lateral
ganglion, nor of the genital or marginal nerves. At least it has not
been possible by any method which I have used to demonstrate their
presence until after the dorsal and ventral commissures, as well as
the dorsal and ventral ganglia, have made their appearance.

3. In the Mature Proglottis.

In each lateral half of every proglottis there is, besides the
dorsal and the ventral commissures and the large lateral nerve, a
dorsal and a ventral longitudinal nerve, an internal and an external
genital nerve, and a marginal nerve. The lateral nerve trunk is im-
bedded in the parenchyma of the body, from which it is not sharply
defined; it is elliptical in cross-section, the larger axis of the ellipse
having a dorso-ventral direction. The course of these nerves is nearly
parallel to that of the longitudinal excretory tube (PL 22, Fig. 6 n. I).
The nerve is a compact bundle of naked axis cylinders separated
from one another by a structureless hyaline matrix, the whole being
bound together by peculiar binding or protecting cells like those found
in the scolex. These cells appear elliptical in outline, and send out
a considerable number of branching processes that run over the sur-
face of the nerve, and serve, I believe, to bind the nerve fibres into
a compact bundle and to separate them in a measure from the tissues
in which the nerve is imbedded (PL 25, Fig. 30-c?.vm). These
branches are not, however, so numerous nor so dendritic in character
as in the cells of similar function figured by ZERNECKE (1896, tab. 13,
figs. 55, 56) for Ligula. In longitudinal sections of the nerve they appear
lenticular, the edges being prolonged for a considerable distance over
the surface of the nerve trunk. In some regions they lie singly, separated
from each other by a considerable distance; in others they lie close
together, as seen in Figs. 9 (PL 22) and 15 (PL 24). There seems to be no

The nervous system in the Cestode Moniezia expansa. 375

regularity as to their arrangement. In VOM RATH preparations the
nuclei of some of these cells are deeply stained and each contains a
very dense nucleolus (vin.d, PL 25, Fig. 29 and PL 24, Fig. 15);
whereas, in other binding cells of the same preparation the nucleus
is unstained, while the nucleolus is deeply stained. Granular cyto-
plasm is usually collected around the nucleus and passes thence in
radiating and sometimes branching strands to the periphery of the
cell, giving the whole a stellate appearance. These are probably
modified mesodermal cells.

Along the course of the lateral nerve between the anterior and
posterior lateral ganglia there are ganglionic cells, some of them in
the nerve itself others outside the nerve. These ganglionic cells are
mostly bipolar or multipolar, but in one case (PL 25, Fig. 30 cl.gn),
two unipolar ganglionic cells were found lying outside the nerve and
sending each an axis cylinder into the nerve. In one case the fibre
shortly left the nerve, and, passing outward, terminated in a cup-
shaped structure, which enveloped one end of an ellipsoidal, hyaline,
structureless body, the other end of which was enveloped by a similar
cup-shaped structure formed by the end of another nerve. I have
observed this structure in several methylen-blue preparations, however
I am inclined to believe that it is due to some post-mortem change
caused by the reagents used. The ganglionic cells which lie in the
nerve substance (PL 24, Fig. 15 cl.gri) are usually small and of the
multipolar type, and are frequently seen to give rise to nerve fibres
which emerge from the nerve.

The lateral nerve is single throughout its entire length, and no
trace of additional lateral nerves, such as have been described in other
Cestodes, has been found.

In the posterior part of each proglottis the lateral nerve becomes
enlarged by the aggregation of ganglionic cells, forming what I have
called the posterior lateral ganglion (PL 22, Fig. 6 gn.lp). It lies
close to the longitudinal excretory tube (PL 25, Fig. 28 and PL 26,
Fig. 31), and nearly opposite the point whence the transverse ex-
cretory tube is given off. The ganglion is ellipsoidal, its antero-
posterior diameter being greater than its dorso-ventral diameter,
which, in turn, is greater than its dextro-sinistral diameter. It varies
considerably in size, being largest in those proglottides which contain very
young embryos while in the older proglottides it undergoes degeneration.

From this ganglion there arise besides several smaller nerves,
two large ones, one from its dorsal, the other from its ventral surface ;

Zool. Jahrb. XIII. Abth. f. Morph. 25

376 , WM. L. TOWEfc,

these pass mediad, one above, the other below the excretory tube,
crossing the proglottis to the corresponding regions of the ganglion
of the opposite side. These two nerves are the dorsal and the ventral
commissures (PL 22, Figs. 6 and 7 corns, d and corns, v). They are
loose, band-like nerves flattened dorso-ventrally, and plentifully sup-
plied with ganglionic cells, either singly or in groups, at points where
nerves are given off. The ganglionic cells are almost always of the
bipolar type (PI. 24, Fig. 20), but otherwise have the same character-
istics as the ganglionic cells from the other parts of the nervous
system. I have not found any binding cells along the dorsal com-
missure, and from its loose texture it is doubtful if any exist.
This nerve in its passage across the proglottis lies slightly behind
the transverse excretory tube and among the transverse muscles,
some of which frequently run through the substance of the nerve.
Because of this peculiarity the nerve is often so broken up and con-
cealed by the bundles of muscles that it is difficult to trace its course.
In places it appears as a moderately compact nerve, but it nuiy
shortly become a mere tangle of nerve and muscle fibres, from which
it may emerge as a broad sheet of nervous tissue. This nerve is
inconstant in form, like all the nerve structures excepting those of
the scolex and the lateral nerves. Its inconstancy of form is due, I
believe, to the fact that the nerve elements lie embedded in the tissues
of the body without any protective structure to bind them into a
compact nerve.

From the outer edge of the posterior lateral ganglion there
arises a cluster of nerve fibres, the largest and most important of which
is the marginal nerve (n. marg). This arises from the anterior portion
of the outer edge of the ganglion, passes outward and then anteriad
through the greater part of the margin of the proglottis (PL 22,
Fig. 6, PL 23, Fig. 12). A short thick nerve arises from the posterior outer
edge of the ganglion, and passes posteriad into the proglottis, which
lies immediately behind that in which the ganglion is located. A
cluster of still shorter branching nerves arises from the lateral margin
of the ganglion between the marginal and the posterior nerves and
is distributed to the outer posterior angle of the proglottis.

The posterior lateral ganglion is made up of a mass of ganglionic
cells and a great number of nerve fibres intermingled in a most
confusing manner. Transverse sections of the proglottis in the
plane of the dorsal and ventral commissures (PL 25, Fig. 28 and
PL 26, Fig. 31) are the most instructive, although frontal sections

the nervous system in the Cestode Moniezia expansa. 377

(PL 21, Fig. 3), are nearly as good. The nerve fibres, on passing
into and out of the ganglion, pursue almost every possible direction,
making a tangle that I have not been able to unravel; yet there
appear to be certain paths within the ganglion that are recognizable,
owing to the number of nerve fibres which take the same direction.
The ganglionic cells associated with the nerve fibres appear in Fig. 28
(PL 25) and Fig. 31 (PL 26) to be of a rounded form, but they are in
reality multipolar, since they each possess numerous protoplasmic pro-
cesses. Isolated cells from this ganglion are shown in Figs. 16 and
17 (PL 24) more highly magnified. Two kinds of these nerve cells
may perhaps be recognized, differing in size and in the richness of
their branching; those which lie in the center of the ganglion are
larger and more richly branched, while those at the periphery are
smaller, usually bipolar, and less richly branched. Otherwise the cells
are alike. The nucleus is rather small, compared with the nucleus of
a ganglionic cell of the scolex, and hyaline, and it contains a deeply
staining nucleolus. In some cases under a very high magnification a
faint chromatic reticulum may be seen in the nucleus. The nuclear
membrane is very thin, with no observed thickenings, and shows no
such wrinkles as are often seen in the scolex. The coarsely granular
cytoplasm is gathered into a mass about the nucleus, from which films
and threads of similar appearance radiate through the more finely
granular cytoplasm that occupies the periphery of the cell. Therefore
these cells invariably have a stellate appearance.

There are also ganglionic cells that lie just outside the ganglion
and send their nerve fibres for the most part into the ganglion. These
cells are usually multipolar, possessing a few dendritic processes.
The nucleus is small, with a large, deeply-staining nucleolus (PL 24,
Fig. 16), and very frequently a well developed chromatic reticulum.
The cytoplasmic contents present the usual stellate appearance. I
have not yet found in the posterior lateral ganglion of the mature
proglottides any of the richly branched binding cells found in the
younger proglottides. Either they are not present (which I can hardly
believe), or, more likely, VOM RATH'S method will not differentiate
them sufficiently in the mature specimens.

Upon the lateral nerve, at about the point where it crosses the
sexual ducts in their passage to the gonopore, there is another ganglionic
enlargement -- the anterior lateral ganglion (gn.l.a, PL 22, Fig. 6,
PL 23, Fig. 12). This is a dorsal enlargement of the lateral nerve
due to the accumulation of ganglionic cells at that point (PL 26,

25*

378 WM. L. TOWER,

Fig. 33), as in the case of the larger posterior lateral ganglion. In
structure it is like the posterior lateral ganglion , being composed of
a number of ganglionic cells embedded in a matrix of nerve fibres,
and the ganglionic cells are in every respect like those of the posterior
lateral ganglion. From the dorsal surface of the anterior ganglion
there arise, sometimes as a single trunk, two nerves which pass
medianward and dorsad and soon divide. One nerve passes laterad,
becoming the external genital nerve (n. gen. ex), and is distributed to
the region of the gonopore; the other passes inward, becomes the
internal genital nerve (n.gen.i, PL 22, Fig. 6; PL 23, Fig. 12;
PL 26, Fig. 33; PL 24, Fig. 27), and is distributed to the ovaries,
uterus, and other sexual organs of the region. There are a few
ganglionic cells along the course of these nerves, but no binding cells.
As far as I was able to discover the anterior lateral ganglion does
not become apparent until the proglottis is nearly mature, although
the two nerves are found in younger proglottides. This is due pro-
bably to the increased activity of those parts upon reaching sexual
maturity.

There is a ventral commissure (PL 22, Figs. 6 and 7 corns, v),
connecting the ventral surfaces of the posterior lateral ganglia of
each proglottis, and corresponding in size, shape and relations to the
dorsal commissure. These two commissures, together with the posterior
lateral ganglia, form a complete nerve ring, embracing the two longi-
tudinal excretory tubes, and uniting the lateral nerve of one side
with its fellow of the opposite side. These two commissural nerves
are united to each other by means of two dorso-ventral connectives.
These connectives have the form of a loose band of nerve fibres that
passes dorso-ventrally from one commissure to the other close to
the median surface of the longitudinal excretory tube, and just behind
the union of the longitudinal and transverse excretory tubes (corft. d-v,
PL 22, Figs. 6, 7; PL 25, Fig. 28; PL 26, Fig. 31). One of these con-
nectives with a small part of each of two commissures and the cor-
responding posterior lateral ganglion forms a complete ring of nerve
tissue that encircles the longitudinal excretory tube immediately behind
the transverse excretory tube. This dorso-ventral connective is like
the commissures in structure, being a band of loosely united nerve
fibres associated with a greater or less number of ganglionic cells.
A few nerve fibres are seen to pass off from these connectives, but I
have not been able to trace them to their terminations.

The marginal nerve (PL 22, Fig. 6 n.marg), arises from the an-

The nervous system in the Cestode Moniezia expansa. 379

terior outer edge of the posterior lateral ganglion, passes outward
for a short distance, and then turning passes forward through about
three-fourths of the length of the proglottis; but in no examples
that I have seen is it continuous through the whole of the proglottis,
as stated by COHN (1897) for Taenia. In my preparations the
branches of the marginal nerve are distributed to the margin of the
posterior three-fourths of the proglottis (PL 23, Fig. 12), only a few
fibres indeed reaching as far forward as the anterior fourth. The fibres
from the short, posteriorly directed marginal nerve ennervate the
greater part of the margin of the anterior fourth of the next following
proglottis, but I was not able to find any branches that extended far
enough backward to meet the fibres of the long marginal nerve. It
is of course possible, in view of the great variability of the peripheral
nerves of the parasites, that there may be cases where the marginal
nerve is continuous and well-marked throughout the entire length of
the proglottis, but I have not yet seen such a case. The structure
of the marginal nerve is shown in PL 22, Fig. 10. Nerve fibres are
given off on all its sides and at frequent intervals, and there are
numerous, spindle-shaped ganglionic cells along its course.

The two dorsal and two ventral nerves discovered by NIEMIEC in
the scolex and neck region of Taenia, are easily demonstrated in the
younger proglottides (PL 21, Fig. 1), and in some cases, at least,
exist in the mature proglottides as well-defined nerves with the
elements closely gathered together. These, which I have described and
figured in an earlier paper, are also represented in the diagrammatic
Figs. 1 (PL 21), 6, 7 (PL 22), 12 and 13 (PL 23). It must not be sup-
posed, however, that these nerves always appear with the same diagram-
matic clearness, for it is only in exceptional cases that they are so well
defined. In the greater number of specimens examined these nerves
had become a loose, ill-defined band of tissue lying in the layer of the
longitudinal muscles, with which the nerve is closely associated. In
my earlier paper I have called these nerves dorsal and ventral con-
nectives, but I am now satisfied that they are continuous throughout
the entire length of the animal, and are therefore equivalent to the
four nerves of NIEMIEC. These nerves pass through, or are closely
associated with, the dorsal and ventral commissures of each proglottis.
At the place of crossing the two form a loose mass of nerve fibres
with an increased number of ganglionic cells. These crossings I have
previously designated as ganglia, and have named them according to
their position in the proglottis. I have continued that nomenclature in the

380 WM. L. TOWER,

present paper, though it may be an open question whether the slight
accumulation of ganglionic cells in these regions warrants giving them
the dignity of ganglia. However, in those cases where the nerve
elements are compacted, these ganglia present a structure not unlike
that of the other ganglia of the nervous system.

The dorsal and ventral longitudinal nerves give off lateral branches
along their entire length, which lie in the layer of the longitudinal
muscles. Fig. 14 (PI. 23) shows one of these nerves (the right dorsal)
which is more compact than usual. In the region of the two branches
there are ganglionic cells.

It gives me pleasure to acknowledge my indebtedness to the
director of the Zoological Laboratory, Dr. E. L. MARK, for his kindly
critericism and many helpful suggestions given me during the progress
of my work.

Cambridge, Mass., Sept. 1, 1897.

Postscript. Since this paper was written COHN (in : Zool. Jahrl>.,
V. 12, Anat, 1899, p. 425—76), has published his studies on the
nervous system of several Cestodes. He believes that all of the
longitudinal nerves, together with their transverse connections in
both scolex and proglottides, constitute the central nervous system.
The branches from these to the various organs and to the surface of
the animal he regards as the peripheral system.

From the conditions that I have found in Moniezia I believe
this division to be justifiable, and that there is a true central nervous
system in Cestodes. I do not, however, agree with CORN'S view that
the "main commissure" is a mere connective. I find in Moniesia that
there is a well developed pair of central ganglia in the scolex. These
ganglia possess ganglionic cells which send nerve fibres to other parts
of the nervous system of the scolex, and posteriorly to the proglottides.

Since this paper was written I have studied further the nervous
system of Cestodes, using with some success methylen-blue and GOLGI
impregnations. I find a distinct central system in the scolex, which
I think may function as a central coordinating center — a brain. The
rest of the central nervous system is comparable to a longitudinal
nerve chain. The conclusions reached in this paper as to the paths
taken by the fibres in the cephalic ganglion were substantiated by
my more recent methylen-blue and GOLGI preparations.

The nervous system in the Cestode Moniezia expansa. 381

Unfortunately all my drawings and preparations were lost in a
fire which occurred in March 1898, and I have not since been able
to return to the subject.

Cambridge, Mass., U.S.A., Dec. 14, 1899.

Literature.

ALT, K., 1892, Ueber Congofarbung (Miinchen. med. Wochenschr. 1892,

No. 4), in: Z. wiss. Mikrosk., V. 9, p. 81.
BLOCHMANN, F., 1895, Ueber freie Nervenendigungen und Sinneszellen

bei Bandwiirmern, in: Biol. Ctrbl., V. 15, p. 14—25.
COHN, L., 1897, Zur Kenntniss der Nerven in den Proglottiden einiger

Tanien, in: Zool. Anz., V. 20, No. 521, p. 4—6.
HODGE, C. F., 1892, A microscopical study of changes due to functional

activity in nerve cells, in: J. MorphoL, V. 7, No. 2, p. 95 — 168,

tab. 7, 8.
KOHLER, E., 1894, Der Klappenapparat in den Excretionsgefassen der

Tanien, in: Z. wiss. Zool., V. 57, p. 385—401, tab. 17—18.
LANG, A., 1881, Untersuchungen zur vergleichenden Anatomie und

Histologie des Nervensystems der Plathelminthen. III. Das Nerven-

system der Cestoden im Allgemeinen und dasjenige der Tetra-

rhynchen im Besondern, in: Mitth. zool. Stat. Neapel, V, 2,

p. 372—400, tab. 15—16.
LONNBERG, E., 1892, Einige Experimente, Cestoden kunstlich lebend zu

erhalten, in: Ctrbl. Bakt., V. 11, p. 89-^-92.
LUHE, M., 1896, Das Nervensystem von Ligula in seinen Beziehungen

zur Anordnung der Musculatur, in: Zool. Anz., V. 19, p. 383 — 384.
NIEMIEC, J., 1885, Recherches sur le systeme nerveux des Tenias, in:

Rec. Zool. Suisse, V. 2, p. 589—648, tab. 18—21.
NISSL, F., 1886, Vorlaufige Mittheilung iiber das Congoroth, in : Miinchen.

med. Wochenschr., 1886, No. 30, p. 528.
REHM, 1892, Einige neue Farbungsmethoden zur Untersuchung des cen-

tralen Nervensystems, in: Miinchen. med. Wochenschr., 1892, No. 13.
STRONG, 0. S., 1895, Notes on neurological methods and exhibition

of photomicrographs, in: Anat. Anz., V. 10, p. 494.
TOWER, W.< L., 1896, On the nervous system of Cestodes, in: Zool.

Anz., V. 19, p. 323—327.
VOM RATH, 0., 1894, Beitrage zur Kenntniss der Spermatogenese von

Salamandra maculosa, in: Z. wiss. Zool., V. 57, p. 97 — 140, tab. 7.

- 1895, Zur Conservirungstechnik, in: Anat. Anz., V. 11, p. 280—288.

ZERNECKE, E. , 1895, Untersuchungen iiber den feinern Bau der

Cestoden, in: Zool. Jahrb., V. 9, Anat. p. 92—161, tab. 8—15.

382

WM. L. TOWER,

Explanation of Plates.

Plate 21—26.

Abbreviations.

a anterior

act acetabulum

cl.gn ganglionic cell

cl. vin binding cell

CO body of cephalic ganglion

corns commissure of cephalic

ganglion

corns, d dorsal commissure of pro-
glottis

corns d' dorsal cephalic commissure
corns, v ventral commissure of pro-
glottis

corns, v' ventral cephalic commissure
con't. cep. dx right connective be-
tween the cephalic and the an-
terior ganglia

con't. d-v dorso-ventral connective
conu. a anterior horn of cephalic

ganglion
conu. ex external horn of cephalic

ganglion
eta cuticula
d dorsal
gn. a. dx-d anterior dextro-dorsal

ganglion
gn. a. s-v anterior sinistro-ventral

ganglion

gn.dx right cephalic ganglion
gn.dx-d dextro-dorsal ganglion
gn.dx-v dextro-ventral ganglion
gn. I. a anterior lateral ganglion
gn. l.p posterior lateral ganglion

gn. s left cephalic ganglion

gn.s-d sinistro-dorsal ganglion

gn. s-v sinistro-ventral ganglion

n. a anterior nerve ring

n. gen. ex external genital nerve

n.gen.i internal genital nerve

n.l lateral nerve

n. Ig. dx-d dextro-dorsal longitudinal

nerve

n. Ig. dx-v dextro - ventral longi-
tudinal nerve
n. Ig. s-d sinistro-dorsal longitudinal

nerve
n. Ig.s-v sinistro-ventral longitudinal

nerve

n.marg marginal nerve
p posterior
ut uterus
v ventral
va.dx right arm of the anterior

loop of excretory tube in scolex
va. dx-d dextro-dorsal longitudinal

excretory tube
va. dx-v dextro-ventral longitudinal

excretory tube

va. Ig longitudinal excretory tube
va.s-d sinistro-dorsal longitudinal

excretory tube
va.s-v sinistro-ventral longitudinal

excretory tube.
va. t transverse excretory tube

The nervous system in the Cestode Moniezia expansa. 383

Plate 21.
Figs. 1, 2, 4 and 5 are diagrammatic.

Fig. 1. Reconstruction of the nervous system in the scolex ot
Moniezia expansa.

Fig. 2. Transverse section of the scolex at the region /?/?' (Fig. 1),
showing the position of the nerve structures.

Fig. 3. Frontal section through the posterior lateral ganglion.
From a VOM RATH preparation. X ^00.

Fig. 4. Transverse section of the scolex at the region aa1 (Fig. 1),
showing the position of the nerve structures etc. (n.l.dx-d should be
n. Ig. dx-d).

Fig. 5. Transverse section of the scolex at the region yy' (Fig. 1),
showing the position of the nerve structures, etc. at that level.

Plate 22.

Fig. 6. Diagrammatic reconstruction of the nervous system in
four proglottides.

Fig. 7. Transverse section of a proglottis through the posterior
lateral ganglion (diagrammatic).

Fig. 8. Diagrammatic representation of the paths taken by the
nerve fibres that enter and leave the cephalic ganglia (see p. 371).

Fig. 9. Parasagittal section through the longitudinal nerve in a
region between the posterior and anterior lateral ganglia, showing
''binding" cells and ganglionic cells lying along the nerve. From a
VOM RATH preparation. X 500. (vt by mistake for ut.)

Fig. 10. Parasagittal section of the marginal nerve, showing nerve
fibres passing off from it. VOM RATH preparation. X 1100.

Fig. 11. Section (transverse to the chief axis of the scolex),
through the dorsal cephalic commissure, showing bipolar ganglionic cells.

Plate 23.

Fig. 12. Portion of a diagrammatic transverse section of a pro-
glottis through the anterior lateral ganglion and the genital nerves,
showing the distribution of the nerve fibres from the marginal nerve,
and from the sinistro-dorsal and the sinistro-ventral longitudinal nerves.

Fig. 13. Parasagittal section (diagrammatic), of a proglottis through
the sinistro-dorsal and the sinistro-ventral longitudinal nerves, showing
distribution of the nerve fibres.

Fig. 14. Portion of a frontal section of a proglottis through a branch
of the dextro-dorsal longitudinal nerve. VOM RATH'S preparation. X 1000-

Plate 24.

Fig. 15. A frontal section of the lateral nerve showing ganglionic
and binding cells. VOM RATH. X 70°-

Fig. 16. Portion of a transverse section of a posterior lateral
ganglion, showing protecting ("binding") cells upon the surface of the

384 WM- L- TOWER, The nervous system in the Cestode Moniezia expansa.

ganglion and two ganglionic cells that send nerve fibres (in another
plane) into the ganglion. VOM BATH preparation. X 1500.

Fig. 17. A bipolar ganglionic cell from the posterior lateral
ganglion. VOM RATH. X 1450.

Fig. 18. A multipolar ganglionic cell from the cephalic ganglion.
VOM RATH. X 1500.

Fig. 19. A bipolar ganglionic cell from the cephalic ganglion.
VOM RATH. X 1450.

Fig. 20. A bipolar ganglionic cell from the posterior lateral
ganglion. VOM RATH. X 1450.

Figs. 21 and 22. Unipolar ganglionic cells from the anterior
ganglia. VOM RATH. X 1450.

Figs. 23 and 24. Bipolar ganglionic cells from the anterior ganglia.
VOM RATH. X 145°-

Fig. 25. A neuron from the lateral nerve in the neck region.
VOM RATH. X 1500.

Fig. 26. A unipolar ganglionic cell from the anterior dorso-dextral
ganglion. VOM RATH. X 1450.

Fig. 27. Frontal section of the anterior lateral ganglion and
genital nerves. VOM RATH. X

Plate 25.

Fig. 28. Transverse section through the posterior lateral ganglion.
VOM RATH. X 80°.

Fig. 29. Protecting cell as seen on lateral nerve. VOM RATH.
X 800.

Fig. 30. Dorso-ventral longitudinal section through lateral nerve
showing protecting and ganglionic cells. VOM RATH. X 1000.

Plate 26.

Fig. 31. Transverse section of the posterior lateral ganglion. VOM
RATH. X 80°.

Fig. 32. Frontal section of the posterior lateral ganglion in the
"neck" region. VOM RATH. X 90°-

Fig. 33. Frontal section through the anterior lateral ganglion.
VOM RATH. X 80°-

Zoolog. JahrbucherBd. IJ.Abth.f.Morph.

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CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OP
THE MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD
COLLEGE.

E. L. MARK, Director.

*** Abbreviations used : —

B. M. C. Z for Bull. Mus. Comp. Zob'l.

P. A. A for Proceed. Auier. Acad. Arts and Sci.

P. B. S. N. II for Proceed. Bost. Soc. Nat. Hist.

1. BARNES, W. — On the Development of the Posterior Fissure of the Spinal Cord, and

the Reduction of the Central Canal, in the Pig. P. A. A. 19 : 97-110. 3 pis. 1884.

2. TUTTLB, A. H. — The Relation of the External Meatus, Tympanum, and Eustachian

Tube to the First Visceral Cleft. P. A. A. 19 : 111-132. 2 pis. 1884.

3. ATEBS, H. — On the Development of Oecanthus niveus and its Parasite, Teleas.

Mem. Bost. Soc. Nat. Hist. S : 225-281. 8 pis. Jan., 1884.

4. WHITMAN, C. O. — The External Morphology of the Leech. P. A. A. 2O : 76-87.

1 pi. Sept., 1884.

5. PATTEN, W. — The Development of Phryganids, with a Preliminary Note on the

Development of Blatta Germanica. Quart. Journ. Micr. Sci. 24 : 549-602. 3 pis.
1884.

6. RKIGHARD, J. — On the Anatomy and Histology of Aulophorus vagus. P. A. A.

20 : 88-106. 3 pis. Oct., 1884.

7. FAXON, W. — Descriptions of New Species of Cambarus; to which is added a

Synonymical List of the Known Species of Cambarus and Astacus. P. A. A.
2O. 107-158. Dec., 1884.

8. LOCY, W. — Observations on the Development of Agelena naevia. B. M. C. Z.

12:63-103. 12 pis. Jan., 1886.

9. FEWKES, J. W. — Report on the Medusae collected by the U. S. Fish Commission

Steamer Albatross in the Region of the Gulf Stream in 1883-'84. Ann. Rep. Comnr.
Fish and Fisheries for 1884, 927-980, 10 pis., 1886.

10. AYERS, H. — On the Carapax and Sternum of Decapod Crustacea. Bull. Essex Inst.

IT : 49-59. 2 pis. 1886.

11. MARK, E. L. — Simple Eyes in Arthropods. B. M. C. Z. 13 : 49-105. 5 pis. Feb.,

1887.

12. PARKER, G. II. — The Eyes in Scorpions. B. M. C. Z. 13 : 173-208. 4 pis. Dec.,

1887.

13. MAYO, FLORENCE. — The Superior Incisors and Canine Teeth of Sheep. B. M. C. Z.

13 : 247-258. 2 pis. Jun., 1888.

14. PLATT, JULIA B. — Studies on the Primitive Axial Segmentation of the Chick.

B. M. C. Z. 17 : 171-190. 2 pis. Jul., 1889.

15. MARK, E. L. — Studies on Lepidosteus. Parti. B. M. C. Z. 19: 1-127. 9 pis.

Feb., 1890.

16. EIGENM ANN, C. II. — On the Egg Membranes and Micropyle of some Osseous

Fishes. B. M. C. Z. 19: 129-154. 3 pis. Mar., 1890.

17. PARKER, G. II. — The Histology and Development of the Eye in the Lobster.

B. M. C. Z. 2O : 1-60. 4 pis. May, 1890.

18. AYERS, H. — The Morphology of the Carotids, based on a Study of the Blood-vessels

of Chlamydoselachus anguineus, Garman. B. M. C. Z. IT : 191-223. 1 pi. Oct.,

1889.

19. DAVENPORT, C. B. — Cristatella : The Origin and Development of the Individual in

the Colony. B. M'. C. Z. 2O : 101-151. 11 pis. Nov., 1890.

20. PARKER, G. II. — The Eyes in Blind Crayfishes. B. M. C. Z. 2O: 153-162. 1 pi.

Nov., 1890.

21. HENCHMAN, ANNIE P. — The Origin and Development of the Central Nervous Sys-

tem in Limax inaximus. B. M. C. Z. 30 : 169-208. 10 pis. Dec., 1890.

22. HITTER, W. E. —The Parietal Eye in some Lizards from the Western United States.

B. M. C. Z. 80 : 209-228. 4 pis. Jan., 1891.

23. DAVENPORT, C. B. — Preliminary Notice on Budding in Bryozoa. P. A. A. 35:

278-282. Mar., 1891.

24. WOODWORTH, W. M. — Contributions to the Morphology of theTurhellaria. — I. On

the Structure of Phagocata gracilis, Leidy. B. M. C. Z. 81 : 1-44. 4 pis. Apr.,
1891.

25. PARKER, G. II. — The Compound Eyes in Crustaceans. B. M. C. Z. ai : 45-142.

10 pis. May, 1891.

26. WARD, II. B. — On some Points in the Anatomy and Histology of Sipunculus

nudus, L. B. M. C. Z. ai : 143-184. May, 1891.

27. FIELD, II. II. — The Development of the Prouephros and Segmental Duct in Am-

phibia. B. M. C. Z. ai : 201-342. 8 pis. Jun., 1891.

28. DAVENPORT, C. B. — Observations on Budding in Paludicella and some other Bryo-

zoa. B.M.C.Z.aa: 1-114. 12 pis. Dec., 1891.

29. SMITH, F. — The Gastrulation of Aurclia flavidula, Pe>. and Les. B. M. C. Z. a? r

115-126. 2 pis. Dec., 1891.

30. JOHNSON, II. P. — Amitosis in the Embryonal Envelopes of the Scorpion. B. M. C. Z.

aa : 127-162. 3 pis. Jan., 1892.

31. BOYER, E. R. — The Mesoderm in Teleosts : especially its Share in the Formation of

the Pectoral Fin. B. M. C. Z. 83 : 91-134. 8 pis. Apr., 1892.

82. WARD, II. B. — On Nectonema agile. B. M. C. Z. 83 : 135-188. 8 pis. Jun., 1892.

33. DAVENPORT, C. B.— On Urnatella gracilis. B. M. C. Z. 84: 1-44. 6 pis. Jan.,

1893.

34. DAVENPORT, C. B. — Note on the Carotids and the Ductus Botalli of the Alligator.

B. M. C. Z. 84 : 45-50. 1 pi. Jan., 1893.

35. KITTKH, W. E. — On the Eyes, the Integumentary Sense Papillae, and the Integu-

ment of the San Diego Blind Fish (Typhlogobius californiensis, Steindachner).
B. M. C. Z. 84 : 51-102. 4 pis. Apr., 1893.

36. NK K KK-.ON. W. S. — The Development of the Scales in Lepidosteus. B. M. C. Z.

84 : 115-140. 4 pis. Jul., 1893.

37. DAVENPORT, C. B. — Studies in Morphogenesis. —I. On the Development of the

Cerata in ^Eolis. B. M. C. Z. 84 : 141-148. 2 pis. Jul., 1893.

38. WOODWORTH, W. McM. — A Method of Orienting •mall Objects for the Microtome.

B. M. C. Z. 85 : 45^7. Dec., 1893.

39. KOPOID, C. A. — On some Laws of Clearftfe in Limax. P. A. A. 8O: 180-203.

2 pis. 1894.

40. DAVENPORT, C. B. — Studies, etc. — II. Regeneration in Obelia and its Bearing on

Differentiation in the Germ-Plasma. Anat. Anz. » : 283-294. 6 figs. Feb. 15,
1894.

41. HOLBROOK, A. T. — The Origin of the Endocardium in Bony Fishes. B. M. C. Z.

85:75-97. 5 pis. Aug., 1894.

42. CASTLE, W. E. — On the Cell Lineage of the Ascidian Egg. A Preliminary Notice.

P. A. A. 3O : 200-216. 2 pis. Oct., 1894.

43. WEYSSE, A. W. — On the Blastodermic Vesicle of Sus scrofa domesticus. P. A. A.

30:283-323. 4 pis. Dec., 1894.

44. WILCOX, E. V. — Spermatogenesis of Caloptenus fernur-rubrum. Preliminary

Notice. Anat. Anz. 1C : 303, 304. Dec. 19, 1894.

45. MILLER, GERRIT S., JR. — On the Introitus Vaginse of certain Muridse. P. B. S. N. H.

86 : 459-468. 1 pi. Feb., 1895.

46. DAVBNPORT, C. B., AND CASTLE, W. E. — Studies, etc. — III. On the Acclimatiza-

tion of Organisms to High Temperatures. Arch. f. Entwickelungsmechauik 8 :
227-249. Jul. 23, 1895.

47. WILCOX, E. V. — Spermatogenesis of Caloptenus femur-rubrum and Cicada tibicen.

B. M. C. Z. 87 : 1-32. 5 pis. -May, 1895.

48. KOPOID, C. A. — On the Early Development of Limax. B. M. C. Z. 87 : 33-118.

8 pis. Aug., 1895.

49. NICKERSON, W. S. — On Stichocotyle nepliropis Cunningham, aParasite of the Ameri-

can Lobster. Zool. Jahrb., Abtli. f. Anat. 8 : 447-480. 3 pis. 1895.

50. DAVENPORT, C. B. — Studies, etc. — IV. A preliminary Catalogue of the Processes

concerned in Ontogeny. B. M. C. Z. 27 : 171-199. 31 figs, in text. Nov., 1895.

51. PARKER, G. II., AND FLOYD, R. — The Preservation of Mammalian Brains by Means

of Forinol and Alcohol. Anat. Anz. 11 : 156-158. Sept. 28, 1895.

52. CASTLE, W. E. — The Early Embryology of Ciona intestinalis, Flemming (L.).

B. M. C. Z. 27 : 201-280. " 13 pis. Jan., 1896.

53. DAVENPORT, C. B., AND NEAL, H. V. — Studies, etc. — V. On the Acclimatization

of Organisms to Poisonous Chemical Substances. Arch. f. Entwickelungsme-
chanik 2 : 564-583. 3 figs. Jan. 28, 1896.

54. PARKER, G. H., AND FLOYD, R. — Formaldehyde, Formaline, Formol, and Forma-

lose. Anat. Anz. 11 : 567, 568. Feb. 14, 1896.

55. PARKER, G. H. — The Reactions of Metridium to Food and other Substances.

B. M. C. Z. 29 : 105-119. Mar., 1896.

56. GEROULD, J. H. — The Anatomy and Histology of Caudina arenata Gould.

P. B. S. N. H. 27: 7-74. 8 pis. and B. M. C. Z. 29: 121-190. 8 pis. Apr.,
1896.

57. PARKER, G. H. — Variations in the Vertebral Column- of Necturus. Anat. Anz. 11 :

711-717. 2 figs. Mar. 29, 1896.

58. WILCOX, E. V. — Further Studies on the Sperinatogenesis of Caloptenus femur-

rnbrum. B. M. C. Z. 29 : 191-206. 3 pis. Jun., 1896.

59. MAYER, A. G. — The Development of the Wing Scales and their Pigment in Butter-

flies and Moths. B. M. C. Z. 29 : 207-236. 7 pis. Jun., 1896.

60. FOLSOM, J. W. — Neelus murinus, representing a new Thysanuran Family. Psyche,

7 : 391, 392. 1 pi. Jun., 1896

61. GOTO, S. — Vorlaufige Mittheilung Uber die Entwicklung des Seesternes Asterias

pallida. Zool. Anz. 19 : 271-273. Jun. 15, 1896.

62. PARKER, G. H. —Pigment Migration in the Eyes of Palaemonetes. A Preliminary

Notice. Zool. Anz. 19 : 281-284. 2 figs. Jun. 29, 1896.

63. WOODWORTH, W. McM. — Preliminary Report on Collections of Turbellaria from

Lake St. Clair and Charlevoix, Michigan. Bull. Michigan Fish Commission,
No. « : 94, 95. 1896.

64. GOTO, S. —Preliminary Notes on the Embryology of the Starfish (Asterias pallida) .

P. A. A. 31 : 333-335. Jul., 1896.

65. WOODWORTH, W. McM. — Report on the Turbellaria collected by the Michigan

State Fish Commission during the Summers of 1893 and 1894. B. M. C. Z. 29 :
237-244. 1 pi. Jun., 1896.

66. TOWER, W. L. — On the Nervous System of Cestodes. Zool. Anz. 19: 323-327.

2 figs. Jul. 20, 1896.

67. DAVENPORT, GERTRUDE C. — The Primitive Streak and Notochordal Canal in Che-

Ionia. Radcliffe Coll. Monographs, No. 8, 54 pp. 11 pis. [Sept.], 1896.

68. LEWIS, MARGARET. — Centrosome and Sphere in Certain of the Nerve Cells of an

Invertebrate. Anat. Anz. 12 : 291-299. 11 figs. Sept. 2, 1896.

69. JUDD, S. D. — Description of three Species of Sand Fleas (Amphipods) collected at

Newport, Rhode Island. Proc. U. S. Nat. Mus. 18 : 593-603. 11 figs. Aug., 1896.

70. JENNINGS, H. S. — The Early Development of Asplanchna Herrickii de Guerne.

A Contribution to Developmental Mechanics. B. M. C. Z. 3O : 1-118. 10 pis.
Oct., 1896.

71. NEAL, H. V. — A Summary of Studies on the Segmentation of the Nervous System

in Squalus acanthias. A Preliminary Notice. Anat. Anz. 12 : 377-391. 6 figs.
Oct. 20, 1896.

72. DAVENPORT, C. B., AND CANNON, W. B. — On the Determination of the Direction

and Rate of Movement of Organisms by Light. Jour, of Physiol. 21 : 22-32.
1 fig. Feb. 5, 1897.

73. DAVENPORT, C. B., AND BULLARD, C. — Studies, etc. — VI. A Contribution to the

Quantitative Study of Correlated Variation and the Comparative Variability of the
Sexes. P. A. A. 32 : 87-97. Dec., 1896.

74. MAYER, A. G. — On the Color and Color-Patterns of Moths and Butterflies.

B. M. C. Z. 30 : 167-258. 10 pis. Feb. [Mar.], 1897 and P. B. 8. N. II. 27 :
243-330. 10 pis. Mar., 1897.

75. PARKER, G. H. — The Mesenteries and Siphonoglvph* in Mctridium margiuutuiu

Milne-Edwards. B. M. C. Z. 3O: 257-272. 1 pi! Mar., 1897.

76. PARKER, G. II. — Photomechanical changes in the Retinal Pigment Cells of Palae-

monetes, and their Relation to the Central Nervous System. B. M. < . /. :io :
273-300. Ipl. Apr., 1897.

77. BUNKER, F. S. — On the Structure of the Sensory Organs of the Lateral I.iin- <>f

Ameiurus nebulosus Le Sueur. Anat. Anz. 13 : 256-260. Mar. 3, 1897.

78. WOODWORTU, W. McM. —On a Method of Graphic Ki-.-,,u-triii-tH>n from s.-i -

tions. Zeit. f. wiss. Mikr. 14 : 15-18. Jul., 1897.

79. BREWSTER, E. T. — A Measure of Variability, and the Relation of Individual Varia.

tions to Specific Differences. P. A. A. 39 : 269-280. May, 1897.

80. DAVENPORT, C. B. — The Rdle of Water in Growth. P. B. S. N. II. 98:73-84.

Jun., 1897.

81. LEWIS, MARGARET. — Clymene prodin-ta sp. nov. P. B. S.N. II. 98 : 111-1K., •_' pN.

Aug., 1897.

82. PORTER, J. F. — Two new Grcgarinida. Jour. Morph. 14 : 1-20. 3 pis. Jun., 1897.

83. Woo DWORTH, W. McM. — Contributions, etc. — II. On some Turbellarm from

Illinois. B. M. C. Z. 31 : 1-16. 1 pi. Oct., 1897.

84. PORTER, J. F. — Trichonympha, and other Parasite* of Tonnes flavipes. B. M . C. Z.

31: : 45-68. 6 pis. Oct., 1897.

85. WAITE, F. C. — Variations in the Brachial and Lumbo-Sacral Plexi of Nerturus

manilosus Rafinesque. B. M. C. Z. 31 : 69-92. 2 pl«. Nov., 1897.

86. DAVENPORT, C. B., AND PERKINS, HELEN. — A Contribution to the Study of Geo-

taxis iu the Higher Animals. Jour, of Physiol. 99 : 99-110. Sept. 1, 1897.

87. PARKER, G. II., AND TOZIER.C. H. — The Thoracic Derivatives of the Postcardinal

Veins in Swine. B. M. C. Z. 31 : 131-144. 5 figs. Mar., 1898.

88. GOTO, S. — The Metamorphosis of Asterias pallida, with Special Reference to the

Fate of the Body Cavities. Jour. Coll. S<-i., Tokyo, 1O : 239-278. 6 pis. 1898.

89. NEAL, H. V. — The Segmentation of the Nemni* System in Squalus a.

A Contribution to the Morphology of the Vertebrate Head. B. M. C. /. :tl :
145-294. 9 pis. May, 1898.

90. LEWIS, MARGARET. — Studies on the Central and Peripheral Nervous s\-t.ni-of

two Polychaete Annelids. P. A. A. 33 : 22:;-2«8. 8 pis. Apr., 1898.

91. HAMAKER, J. I. — The Nervous System of Nereis virens Sars. A Study in < ..m-

parative Neurology. B. M. C. Z. 39 : 87-124. 5 pis. Jun., 1898.

92. FIELD, \V. L. W. — A Contribution to the Study of Individual Variation in the

Wings of Lepidoptera. P. A. A. 33 : 389-396. 5 figs. Jun., 1898.

93. MARK, E. L. — Preliminary Report on Branchiocerianthus urceolus, A nru TM>' «»:'

Actinian. B. M. C. Z. 39 : 145-154. 3 pis. Aug., 1898.

94. SARGENT, P. E. — The Giant Ganglion Cells in the Spinal Cord of Ctenolabrus

coerueus. Anat. Anz. 15; 212-225. 10 figs. Dec. 20, 1898.

95. RAND, H. W. — Regeneration and Regulation in Hydra viridis. Arch. Entwickel-

ungsmechanik, 8 : 1-34. 4 pis. Feb. 21, 1899.

96. FOLSOM, J. W. — The Anatomy and Physiology of the Mouth-Parts of the Collem-

bolan, Orchesella cincta L. B. M. C. Z. 35 : 5-39. Jul., 1899.

97. MARK, E. L. — " Branchiocerianthus," a Con-ection. Zool. Anz. 99: ^74, J7 ..

Jun. 26, 1899.

98. BANCROFT, F. W. — Ovogenesis in Distaplia occidentalis Ritti-r (MS.) , with Remarks

on Other Species. B. M. C. Z. 35 : 57-112. 6 pis. Oct., 1899.

99. GALLOWAY, T. W. — Observations on Non-sexual Reproduction in Dero vaga.

B. M. C. Z. 35 : 113-140. 5 pis. Oct., 1899.

100. PARKER, G. H. — The Photomechanical Changes in the Retinal Pigment of Gain-

marus. B. M. C. Z. 35 : 141-148. 1 pi. Oct., 1899.

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