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The Growth of Organs in the
Albino Rat as Affected by
Gonadectoniy

SHINKISHI HAT A I

From the Wistar Institute of Anatomy and Biology

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Reprinted from The Journal of Experimental
Zoology, Vol. 18, No. 1, January, 1915

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Reprinted from The Journal of Experimental Zoology, Vol. 18, No. 1
January, 1915

THE GROWTH OF ORGANS IN THE ALBINO RAT AS
AFFECTED BY GO^ADECTOMY

SHINKISHI HATAI

The Wistar Institute of Anatomy and Biology

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The object of the present paper is twofold. (1) To test the
several findings given in my previous work on the effect of gon-
adectomy (Hatai C3) and (2) to extend similar observations to
several other ductless glands besides the hypophysis and ovaries.
Furthermore, the present paper includes observations on the
effect of semi-castration, ligation of the spermatic cords, and
isolation of the ovaries from the uterus. In some series the weight
and length of various bones, as well as the weights of parts of
the encephalon, have been investigated also.

For this discussion I have found it convenient to introduce
the word ‘gonadectomy;* a word proposed to cover both castration
and spaying. As the literature shows, the word ‘castration*
is often used for operations on both males and females, while
in some instances castration is applied only to operations on the
males; and for those on the female the word ‘ovariotomy* or
‘spaying* is used. This double use of the word ‘castration,*
signifying either the removal of the testes alone, or the sex
glands of both sexes, makes for confusion.

The term ‘gonadectomy* is useful therefore not only because
it reduces to one word the expression “removal of the sex glands
in either sex’* but also because it leaves ‘castration* to apply
to the operation on the male, while that on the female is desig-
nated by ‘spaying.* In this paper, therefore, the word gonadec-
tomy is used throughout, whenever reference is made to the
removal of the sex glands in both sexes, or without distinction
of sex.

m

1

THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 18, NO. 1
JANUARY, 1915

2

SHINKISHI HATAI

MATERIAL

The albino rats which have been used were obtained from the
colony at The Wistar Institute during 1912 to 1913. The
individuals belonging to the same litter were divided into two
lots; one lot for control and the other for operation. The com-
parison is thus made always within the litter. This method of
comparison is the best, since as shown by Jackson (T3) the
variability of the body weight in the litter is only about one
half that in the total population. It is further the impression
of the present writer that peculiarities, when present, are usually
found in most of the members of the same litter.

In the majority of instances the rats were subjected to oper-
ation at the age of 20 to 30 days, but in some series the operation
was done at three different age periods with a view to determin-
ing the effect of age on the results. All the operations were
performed by Dr. Stotsenburg at The Wistar Institute and I
wish to acknowledge with thanks his courtesy in this matter.
The method of the operation has been published by Dr. Stotsen-
burg (’09). The method for removal of the various organs after
death is given in my papers published recently (Hatai T3, T4)
and any other methods which have not already been given there
will be described later.

Usually the operated rats were placed in the same cage with
the controls. Thus one cage (1x1x5 feet) was occupied by
all the individuals belonging to a given litter. If, however, the
litter comprised more than six individuals, it was divided between
two cages. The operated and control animals were thus treated
similarly during the period of observation, and furthermore,
the normal rats in the litter were allowed to breed. The object
of doing this was to keep the rats under as natural conditions
as possible.

Since we already have sufficient data on the growth of the body
in weight following gonadectomy, the rats used for the present
investigation were not weighed while under observation. The
operated and control rats were examined on the same day unless
the appearance of disease necessitated an early killing of one
or the other.

GROWTH AS AFFECTED BY GONADECTOMY

3

FORMULAS

In order to determine the amount of deviation of any character
(e.g., the weight of the organ, external measurements, etc.)
in the operated animals from the same character in the controls,
there are two methods which are commonly used:

1. The weights of the organs (for example) belonging to both
the controls and operated are directly compared, irrespective
of the difference in the body weights or ages of the animals
employed. So long as the weight of the organ varies with the
weight of the body or with the age of the animal, this method is
obviously misleading, nevertheless, it has been used by a sur-
prisingly large number of investigators.

2. The second method, which is more commonly employed,
is to determine the ratio between the weight of the organ and
that of the body and then to compare the magnitude of the
ratios for both the controls and the operated. This method
is, however, not always satisfactory and indeed in some cases
may even lead to an entirely wrong conclusion when the relation
between the body weight and the organ weight during growth
deviates widely or irregularly from linearity. It is evident,
therefore, that the safer method is to make a preliminary study
of the phases of the normal growth of thfe organ or organs of the
species in unoperated individuals in order to obtain data by
which to estimate the relative deviations more correctly, or
at least to avoid any misinterpretations arising from the peculiar-
ities in the growth of the organs with respect to either body
weight, body length or age.

Fortunately, in this laboratory we have at hand for the albino
rat very adequate data on all the organs and characters under
consideration, and furthermore from these data the mathematical
formulas have been worked out in order to facilitate interpola-
tion, as well as to study the forms of the growth curves for these
characters.

I shall now indicate the method I have employed of computing
for any animal examined, the magnitude of the deviations by
the use of the formulas. All the formulas which are used in the

4

SHINKISHI HATAI

present investigation have been given in my papers recently
published (Hatai, ’13, ’14) and therefore they will not be re-
peated here.

In determining the deviation of the organs, I have chosen
the body length as the basis for the computation since this is
the character of the body least subject to incidental modification.
As a first step, the weights of the various organs corresponding
to the observed body length of the rats under examination are
computed by means of formulas. This computation is made
for both the controls and the operated animals. The computed
values thus obtained usually differ from the observed values,
though this difference is not always significant. The differences
between the observed and computed values of both operated
and controls are now transformed into percentages by taking
the computed values as 100 per cent. Thus we obtain two
sets of percentage values, one expressing the difference between
the computed and observed values in the control rats, and the
other expressing the differences between computed and observed
values in the operated rats. If the operation has not altered the
organs of the animals at all, then these two sets of percentages
should be alike within the limits of the normal fluctuations. If,
on the other hand, the operation has altered the organs, these
two sets of percentages should differ more or less according to
the nature of the response to gonadectomy. If we now take
the differences of these percentage values as given by the con-
trols and by the operated rats, these differences represent the
values by which the operated animals depart from the controls:
the body length being used always as the standard for the com-
putations. I have given in table 1 an illustration of the process
of computation as here explained.

It must be stated, however, that in the case of the thymus
gland, age is taken as the basis for the computation, since the
weight of the thymus is much more highly correlated with the
age of the rat than with either the weight or the length of the
body (see Hatai T4). Again, in the case of the percentage of
water in the central nervous system, I have taken the differences
directly from the observed percentage values, since the per-

GROWTH AS AFFECTED BY GONADECTOMY

5

centage of water is a function of the age of the animal (subject
to a slight correction for the absolute weight of the central
nervous system — Donaldson) and hence so long as the ages of
the control and operated rats are identical, this direct method
is sufficiently accurate.

CASTRATION OF ALBINO RAT
CASTRATION AT 16 TO 22 DAYS OF AGE

This experiment is based on 16 litters comprising 27 controls
and 26 operated rats. These 16 litters have been distributed
in 6 groups, each containing two or more litters. In all cases
the grouping was so made as to bring together those in which
the average body lengths of the controls were most similar. The
animals were examined 138 days after operation and the results
of the observations are given in table 2.

Body length. If we compare the observed body lengths of the
control and the castrated rats, it is noted that the castrated
have a body length slightly less than that of the controls. This
occurs in all six groups and gives an average difference of 4 per
cent in favor of the controls. In the two previous studies (Don-
aldson and Hatai Tl, and Hatai T3) we also noticed a similar
reaction, that is the body lengths were absolutely shorter in the
castrates than in the corresponding controls. We conclude
therefore that the castration of young rats hinders the growth
of the body in length.

Tail length. It has been noted in my previous study (Hatai
’13) that, with respect to the body length, the tail lengths of the
castrated rats are slightly greater than those of the controls.
The average difference was 5.2 per cent in favor of the castrates.
We notice in the present experiment the same degree of deviation;
that is, the tails of the castrates are on the average 4.7 per cent
longer than those of the controls.

We did not determine the tail length for the rats of the 1909
series. As the tail of the female rat is normally slightly longer
than that of the male, this modification of the tail length brings
the castrated male rats nearer to the female in this respect.

6

SHINKISHI HATAI

Since the anal opening is taken as the point dividing the body
from the tail, the question arises whether the longer tails in
the operated rats might have been due to the shifting of the anus
following removal of the testes, the length of the caudal verte-
brae not being altered. As will be seen later, the tail length
of the rats whose spermatic cords had been ligated are also
longer than those of the controls, to the same extent as in the
castrates, despite the fact that these rats have the scrotum of
normal size (though filled mostly with fat and connective tissue)
and in the normal position. This seems to indicate that in the
castrates the elongation of the tail with respect to the body
length should not be attributed to a mere shift of the anus.
Whatever be the real cause of this phenomenon, we note with
interest the definite alteration of this external measurement as a
result of castration.

Body weight. The absolute body weights of the castrated
rats are slightly below those of the controls. This is to be ex-
pected since the body length, which is correlated with the body
weight, is less in the castrates than in the controls. When,
however, the body weights in the two series are compared with
respect to the body length, the castrates show a relatively heavier
body weight, though the average difference is only 6 per cent
above that of the controls. This difference is certainly small
when the normal amount of the fluctuation is considered, never-
theless it occurs in five out of the six groups, and therefore it
should not be neglected. In my previous study (Hatai T3)
the corresponding difference in favor of the castrates was found
to be 3.6 per cent. It seems therefore probable that there is
some tendency to a slight overgrowth in body weight with respect
to the body length as the result of castration. Although precise
tests have not been made, this increase does not seem to be due
to an excess of fat, as in the case of the spayed rats, since the
post mortem examination shows no evident difference in the fat
deposition in the two groups.

GROWTH AS AFFECTED BY GONADECTOMY

7

Ductless glands

Thyroid gland. Table 2 shows that the thyroid of the cas-
trates weighs less than that of the controls. The average defi-
ciency is 21.5 per cent. This deficiency occurs in five groups out
of the six. It should be noted, however, that the difference
ranges from —0.8 per cent to —90.3 per cent and this wide range
of variation must undoubtedly be taken into consideration as
the normal variability of the thyroid gland is very high. For
this reason an interpretation of the results will be postponed
until the relations of the thyroid in the remaining series have
been presented.

Suprarenal glands. We notice that these glands show .a regular
increase in the castrates as compared with the controls. On the
average this amount is 17.6 per cent. The amount of the devia-
tion is quite regular, being from 12.8 per cent to 21.4 percent.
Furthermore, the increase is shown in all six groups, thus indi-
cating the significance of the results despite the rather moderate
magnitude of the alteration.

Thymus gland. The thymus gland and hypophysis are the
two organs which exhibit the most striking reactions after cas-
tration. As is shown in table 2, the thymus of the castrates is
on the average 61.2 per cent greater than that of the controls.
The range of variation is quite uniform with the exception of
one undoubtedly abnormal instance (group X) and extends
from 63.5 per cent to 87.4 per cent. If we neglect the unusual
instance of 3.2 per cent in Group X, we obtain an average in-
crease of 72.7 per cent instead of 61.2 per cent, as given in table 2.

Hypophysis. The hypophysis also shows a striking alteration
as the result of castration. This amounts on the average to
56.7 per cent. The increase is present in all the groups and its
value ranges from 45.0 per cent to 67.0 per cent. The present
experiment confirms fully the results obtained from the castrated
rats during 1912 (Hatai T3) where the increase in the hypophysis
was found to be 75.6 per cent.

The somewhat smaller response in the present series may
probably be correlated with a slight overgrowth of the body in

8

SHINKISHI HATAI

weight as contrasted with that found in the previous study.
As will be seen later, there is a close reciprocal correlation between
increase in the weight of the body including the fat and the
increase in the weight of the hypophysis.

Central nervous system

Brain weight. As will be seen from table 2, the brains of the
castrates show a slight but constant overgrowth when compared
with these of the controls. The excess is 2.6 per cent on the
average. We have noted in two previous studies a slight de-
crease instead of an increase, though the amount of decrease
was by no means large. Thus we found in the castrates, —3
per cent in the 1911 series (Donaldson and Hatai Tl) and —0.3
per cent in the 1913 series (Hatai T3). This lack of correspond-
ence in the results suggests that the differences noted here may
be fluctuations merely.

Spinal cord weight. Like the brain, the weight of the spinal
cord shows fluctuations which are however slightly greater
than those in the brain. On the average we find in this study
an increase of 3.3 per cent in the cord weight in favor of the
castrates. Further, this increase is shown in five out of six
groups. In the 1910 series (Donaldson and Hatai ’ll) there
was found a deficiency of 5.3 per cent; on the other hand, in the
1912 series (Hatai T3) an increase of 3.0 per cent, and finally
in the present series an increase of 3.3 per cent. In addition
to these results just mentioned, the values obtained from other
experiments which will be described, suggest that the results
are probably mere cases of fluctuation, and not to be causally
related with gonadectomy. This subject will be discussed
later.

Water content in the brain and in the spinal cord. The water
content of the central nervous system is practically unaltered
by castration. We note from table 2 the difference of 0.01 per
cent in the case of the brain and 0.20 per cent in the case of the
spinal cord, both in favor of the castrates. This result agrees
with those of the two previous series, and thus it seems safe to

GROWTH AS AFFECTED BY GONADECTOMY

9

conclude that the percentage value of the water content of the
central nervous system is not altered by the removal of the testes.

In order to determine the effect of age on the results of castra-
tion, a small number of rats were operated upon at two other
periods: one lot at 79 to 93 days and the second lot at 208 to
232 days. The results are shown in table 3 and table 4.

CASTRATION AT 79 TO 93 DAYS

This experiment comprised four litters represented by 6 con-
trol and 5 operated rats. These were examined 111 days after
operation. We note from table 3 that the results obtained from
the present series are not essentially different from those obtained
where the rats were castrated between 16 and 22 days of age.
In this series we shall comment only on the values obtained for
the thyroid and for the central nervous system.

In the case of the thyroid, the increase is 3.8 per cent against
— 21.5 per cent after early castration, and in the case of the brain
and spinal cord, the increases are 0.5 per cent and 0.3 per cent
respectively as against 2.6 per cent and 3.3 per cent always in
favor of the castrates. These results suggest strongly that the
variations recorded in the previous series are probably mere
fluctuations.

CASTRATION AT 208 TO 232 DAYS

This study comprises three litters represented by 7 controls
and 8 castrates. The animals were examined at 273 days of age
or 55 days after operation. The reactions shown by this oldest
series are again similar to those of the two previous series. The
highest fluctuations are shown by the thyroid and the central
nervous system. The remaining characters show somewhat
less difference between the controls and castrated than is found
in the two previous series. This slight response may be due
either to the shorter interval between operation and examination,
or to the advanced age at operation which finds the animals
less responsive.

10

SHINKISHI HATAI

We note with particular interest the average increase of the
thymus gland (53.9 per cent) even at this advanced age. In
the normal rat the thymus gland reaches its maximum weight
at about 85 days and then begins to diminish in absolute weight
very steadily. Indeed at 200 days its loss in weight from the
maximum value is nearly 44 per cent (Hatai 7 14) yet even after
this atrophy it appears that the thymus is capable of responding
to castration to nearly the same degree as when the operation is
performed on younger rats.

Parts of the encephalon

We have noted that the weight of the brain is not noticeably
modified by castration, nevertheless it was thought possible
that the relative weights of the different parts of the brain might
have been modified. To test this the brain was divided into
four parts: cerebrum, stem, cerebellum and olfactory bulbs,
in the following way:

1. Olfactory bulbs. The brain is placed with the dorsal side
up and with a very sharp scalpel the olfactory bulbs are cut
from the rest of the encephalon by section of the olfactory
tracts just caudad to the bulbs. The portions thus separated
are designated as the olfactory bulbs.

2. Cerebellum. The cerebellum is next removed by severing
with sharp scissors the several peduncles.

3. Cerebrum. The cerebrum is separated from the stem by
cutting with a scalpel carried in the plane passing just in front
of the dorsal edge of the anterior colliculi and just caudad to the
corpus mammillare.

4. The remaining portion, caudad to this plane of section, is
the stem.

The results of this investigation are given in table 5. The
rats used for it belonged to the series castrated at 16 to 22 days.
They were arranged according to age instead of body length,
since the relative weights of the parts of the encephalon are more
closely correlated with age.

GROWTH AS AFFECTED BY GONADECTOMY

11

The total number of the animals used was 22 control and 22
castrated, and these were examined in 6 age groups. In each
group the controls and castrated belong to the same litters.
As will be seen from table 5, there is practically no difference
in the proportional weights of the parts of the brain in the two
series. There is however some slight tendency to a relatively
smaller weight of the olfactory bulbs in the castrates. The
observations are too few and the difference too slight, however,
to justify us in putting emphasis on the deviation now. I there-
fore conclude that so far as the observations go, there is no
important difference between controls and castrates in the relative
weights of the parts of the brain.

Weights and lengths of certain hones

In order to determine whether or not castration produces
modifications in the skeletal system of rats, some bones, the
humerus, radius and ulna, femur and tibia «and fibula, were
examined. The preparation of the bones was as follows:

The fresh bones were roughly cleaned by dissection and then
put into a hot solution of 2 per cent “gold dust cleaning powder”
(a commercial preparation) for nearly two 'hours. The period
of course varies slightly according to the size and age of the
specimens. As soon as the remaining soft parts were mace-
rated, the bones were cleaned with a strong tooth brush, with
an occasional use of the bone scraper. These bones thus cleaned
were gently wiped with blotting paper and weighed. This
weight is designated here as the ‘fresh weight.' The bones were
then placed in small vials without corks. After about eight
months these bones were again weighed and the amount of mois-
ture was determined — this gave the ‘dried weight.'1 It may be
stated that we have had a large experience with the method of
preparation in connection with other investigations in this

1 This is not to be confused with the weight of ‘dry substance/ to be obtained
by subjecting the bones to a temperature of 95° C., until they reach a cqnstant
weight.

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SHINKISHI HATAI

laboratory, and the above method has been found to be perfectly
trustworthy for purposes like the present.

The method just given has been applied to all the other
series (after spaying and semi-spaying) in which the bones have
been studied. The results of this examination are given in table
6. The final averages from table 6 show the following relations :

BODY LENGTH TO AV.

BODY WFIGHT TO

WATER CONTENT IN

BONE LENGTH

BONE WEIGHT

PER CENT

Controls 1:0.141

1:0.0124

25.14

Castrated 1:0.142

1:0.0129

27.29

We note from these relations that the difference between
the controls and the castrates is very slight, except in the water
content in which a difference is clearly indicated. It must be
noted, however, that when examined by litters there is a tendency,
though slight, for the castrated rats to give constantly a small
relative excess in * both length and weight of the bones. The
small excess is shown in all four groups. At the same time it
must be admitted that the difference is certainly much smaller
than might have been anticipated from the reports of previous
investigators who have discussed the modification of the skeleton
after castration.

SPAYING OF THE ALBINO RAT
SPAYING AT 19 TO 30 DAYS OF AGE

The present observations are based on 15 litters comprising
30 controls and 28 spayed. These 15 litters were arranged in
6 groups according to the method adopted for the previous
series. The animals were examined from 101 to 190 days after
the operation. The results are shown in table 7.

Body length. If we compare the absolute values of the body
lengths of the control and spayed, we note a slightly longer body
in the spayed. Though the difference is only 2.5 per cent in
favor of the spayed, nevertheless it occurs in five out of six groups,

GROWTH AS AFFECTED BY GONADECTOMY

13

>

while the remaining group shows equality. The significance
of this difference is enhanced, despite its small value, by the fact
that it has been observed in a previous study (Hatai T3) that
the spayed show an increase of 2.7 per cent in body length over
that of the controls. From these two studies, which present
the same degree of increase, we may safely conclude that spaying
stimulates the growth of the body in length. It is interesting
to note in this connection that castration as already pointed out
(see page 5) has the reverse effect.

Tail length. With respect to the body length, the tails of the
spayed are slightly longer than those of the controls. The
average increase is 1.9 per cent in favor of the spayed. This
increase, however, may not be at all significant, unlike the re-
action in the case of the castrates, as it is highly irregular. More-
over, the two other spayed series, which will be presented later,
show a decrease in one case and an increase in the other in the
length of the tail. These results can best be taken as indicating
a statistical variation rather than a significant modification
produced by the removal of the ovaries.

Body weight. The body weight with respect to the body length
is greater in the spayed than in the controls. The average
value gives an increase of 7.3 per cent in favor of the spayed.
The range of this increase is high, being from 2.2 per cent to 13.2
per cent, nevertheless it is always in the same direction; that is
the spayed have a relatively heavier body. The same response
was noted in my previous study on spaying (Hatai T3) though
the difference there found was only 3.1 per cent. This low
value obtained from the 1912 series was due to the somewhat
emaciated condition of some of the rats at the time of killing.
We conclude, therefore, that the spayed rats are longer and
heavier, while the tail length is not altered by spaying. It
should be added here that the spayed rats belonging to the pre-
sent series did not show as much obesity as those belonging to
some previous series (see Stotsenburg ’13, and Hatai ’13). This
fact is important since the variations in the degree of obesity
are intimately related with the variations in the weight of the
hypophysis.

>

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14

SHINKISHI HATAI

Ductless glands

Thyroid gland . As in the case of the castrates, the thyroid
gland of the spayed shows considerable fluctuation in weight.
Although on the average spayed have a slightly heavier thyroid
(3.3 per cent) nevertheless we find an increase in three groups
and a decrease in the remaining three, and in addition to this
inconstancy the range of variation is also very great. We shall
therefore postpone the discussion of this to a later occasion.

> Suprarenal glands. The suprarenal glands of the spayed are
smaller than those of the controls. The difference on the aver-
age is 18.5 per cent against the spayed. This diminution in
the spayed occurs in all six groups, while the range of variation
is not so great if we omit one instance, giving an exceptionally
small value (group 9, in which the difference is —5.7 per cent).
Furthermore, the two remaining spayed series also show a
corresponding diminution and thus we may safely conclude
that spaying hinders the normal rate of growth of the suprarenal
glands in respect to the body weight.

It is interesting to recall that castration tends to increase the
weight of the suprarenal glands — just the opposite effect to that
produced by spaying. Since normally the female rat has larger
suprarenals than the male, and since castration increases, while
spaying diminishes the weight of these glands, we see that as
the result of gonadectomy the two sexes tend to approach one
another in this character.

Thymus gland. The thymus gland of the spayed shows a
most striking alteration. In some cases its increase runs as high
as in the castrates, and indeed on the average it shows an increase
of 58.3 per cent in favor of the spayed. This increase in the
spayed occurs in all six groups, and thus the causal connection
between the greater size of the thymus and removal of ovaries
is clearly shown. The range of increase, 34.2 per cent to 75.8
per cent, was higher than might be anticipated on account of
the two groups in which the increase was rather small.

Hypophysis. The hypophysis shows a distinct increase of
8.9 per cent in the spayed rats. This increase ranges in the

GROWTH AS AFFECTED BY GONADECTOMY

15

several groups from 0.3 per cent to 21.6 per cent. However,
it occurs in all the groups and furthermore it has been noted in
my previous study (Hatai '13). It is interesting to observe
that in. general the increase of the hypophysis is negatively
correlated with gain in body weight.

Central nervous system

Brain weight. The relative brain weight of the spayed rats
is slightly heavier than that of the controls. On the average
the difference is 1.3 per cent, and it occurs in five out of six
groups. The other two studies on spayed rats, to be presented
later, give in one study similar values, and a decrease in the
other. These irregularities suggest that the increase recorded
in the present series should be regarded as a fluctuation.

In my previous study (Hatai T3) the spayed rats showed a
decrease of 0.4 per cent in the weight of the brain. This dis-
agreement between the results of two successive years supports
the view that we are here dealing with a fluctuation only.

Spinal cord weight. The spinal cord of the spayed rats shows
a still greater relative increase than does the brain. On the
average, the spayed shows 2.5 per cent increase, and furthermore
this occurs in five out of the six groups. A slight increase in
the spinal cord weight has also been observed in a previous
study (Hatai H3) and in view of the fact that the increase occurs
in all operated animals (see all the experiments reported in this
paper) we are hardly justified in regarding it as a mere fluctuation,
though at the same time there does not seem to be any reason
to expect this increase. I shall therefore leave this point without
attempting any interpretation at the present time.

Percentage content of water in the central nervous system. The
amount of water present in both the brain and spinal cord is
not altered by the removal of the ovaries. We note from table
7 only an insignificant difference between the control and spayed
rats. This result agrees fully with that of the two previous
studies and we may conclude therefore that the water content
of the nervous system remains unmodified. In addition I have

16

SHINKISHI HATAI

studied two other series represented by the albino rats spayed
at more advanced ages: (1) Spayed at 97 to 119 days and (2)
spayed at 172 to 195 days of age.

AFTER SPAYING AT 97 TO 119 DAYS OF AGE

This series comprises five litters containing 9 controls and
8 spayed. These rats were examined 100 days after spaying.
The results of the operation are shown in table 8. We find in
this series a general agreement with the previous results.

Body length. The absolute value of the body length of the
spayed is slightly greater than that of the controls. This agrees
with the previous observation.

Tail length. The relative tail length of the spayed is slightly
shorter (1.5 per cent) as against the slight increase in the pre-
vious series. This disagreement suggests that the variations in
tail length are merely fluctuations.

Body weight. The body weight of the spayed rats shows a
slight relative increase and thus agrees with the previous obser-
vations.

Thyroid gland. The thyroid of the spayed shows 50.6 per
cent decrease as against 3.3 per cent increase in the previous
series. This disagreement indicates that the variations shown
by this organ are probably fluctuations or dependent on con-
ditions not yet recognized.

Thymus gland. We not§ 39.6 per cent increase in the spayed.
This result agrees with the previous observations.

Hypophysis. The hypophysis of the spayed shows 7.8 per
cent increase. The results agree with the previous observations.

Brain weight. As before, there is no difference in the weight
of the brain between the controls and the spayed.

Spinal cord weight. There is a very slight increase of 1.5
per cent in the weight of the spinal cord of the spayed. This agrees
with the previous observations.

The percentage of water in the central nervous system shows no
significant variations.

GROWTH AS AFFECTED BY GONADECTOMY

17

AFTER SPAYING AT 172 TO 195 DAYS OF AGE

This series comprises three litters containing 9 controls and
7 spayed rats. The rats were examined 27 to 60 days after
operation. The results are shown in table 9. This series shows
alterations essentially similar to those found in the two pre-
ceding series, and therefore a detailed description may be omitted.

We note with special interest the reaction shown by the thy-
mus gland after spaying. It has been stated already that the
thymus gland at 200 days is nearly 44 per cent less than at the
maximum stage (at 85 days). Thus even in this advanced
stage of involution the thymus gland responds to spaying and
shows an average increase of 27.5 per cent. In one case, group
14, the increase is as high as 60.8 per cent, or almost as great as
in the rats operated at 19 to 30 days. All the other characters
show the alterations we should expect from the two preceding
series.

Parts of the encephalon

The parts of the encephalon of the spayed rats have been ex-
amined to see whether or not any differences in the relative
weights between the spayed and controls can be detected. The
methods of dissecting the brain, as well as of grouping the rats,
were the same as used in the case of castration. The results
of the investigation are given in table 10. As will be seen from
the table, there is no significant difference in the relative weight
of the parts of the brain in the spayed and in the controls. If
we examine the different groups we note some tendency to
relatively small olfactory bulbs in the spayed. The difference,
however, is too slight to be regarded as of value. We conclude
therefore that removal of the ovaries has no marked effect on the
relative weights of the parts of the encephalon.

Weights and lengths of certain hones

The weights and length of the bones of the spayed, together
whith those from the controls, were investigated. The technique
used and bones examined were the same as in the case of the
castrated rats. The results of the investigation are given in

THE JOURNAL OP EXPERIMENTAL ZOOLOGY, VOL. 18, NO. 1

18

SHINKISHI HATAI

table 11. From the final average given in the table we find the
following relations:

BOpy LENGTH TO AV.

BODY WEIGHT TO

WATER CONTENT IN

BONE LENGTH

BONE WEIGHT

PER CENT

Controls

1:0.146

1:0.0134

23.44

Spayed

1:0.148

1:0.0128

25.35

From the above it appears that the differences in the relative
values between the controls and the spayed are very slight.
Nevertheless, we note as in the case of the castrates, that the
spayed give a slightly higher value in the case of the bone length.
In the case of the bone weight, the spayed rats give a less value.
In this instance the weight relation is due to the abnormal fat
deposition which follows spaying. According to the formula,
a body length of 188 mm. (that of the spayed) should give a
body weight of 170 grams, while the observed body weight of
the spayed is 186.1 grams, thus showing a difference of more
than 9 per cent. If therefore we take a corrected body weight
of 170 instead of 186.1 grams, the ratio between the body and
bone weight becomes 1:0.140, or the spayed have a slightly
heavier relative bone weight than that of the controls.

The water content is distinctly greater in the spayed, thus
agreeing with what was found for the castrates. We conclude
then that gonadectomy in the rat tends to give rise to very
slightly longer and heavier bones, which in turn have a higher
water content than those of the controls.

SEMI-CASTRATION OF THE ALBINO RAT
AFTER SEMI-CASTRATION AT 17 TO 27 DAYS OF AGE

This series comprises 15 litters containing 22 controls and 24
semi-castrated rats. These 15 litters were placed in five groups
according to the method previously employed. The results
are given in table 12.

Body length. The semi-castrated rats did not grow in length
as much as the controls. In this respect the semi-castrated are

GROWTH AS AFFECTED BY GONADECTOMY

19

similar to the castrates. On the average we find that the semi-
castrated give a body length of 209 mm. against 217 mm. for
the controls; a differentce of 3.7 per cent in favor of the controls.
This relation is true not only on the average, but appears also
in four out of the five groups. In view of these uniform results,
we draw the tentative conclusion that semi-castration hinders
slightly the normal growth of the body in length.

Tail length. In four out of five groups the tail length of the
semi-castrated is greater than that of the controls. On the aver-
age, the difference is 1.9 per cent in favor of the semi-castrated.
It is evident that the amount of increase is hardly one third of
that given by the castrates, and further the fluctuation is much
greater than that of the castrates. Moreover, since we find a
decrease in the relative length of the tail in the semi-castrates
given in the next series, we conclude that the differences repre-
sent mere fluctuation, and that the length of the tail is not modi-
fied by semi-castration.

Body weight. The relative body weight is slightly greater in
the semi-castrated than in the controls. We find on the average
a difference of 1.9 per cent in favor of the semi-castrated. The
increase is shown in five out of six groups, and further the range
of variation is not large. This seems to be an instance of a
slight tendency to an increase of the body weight as the result
of the operation.

Testes. The surviving testis of the semi-castrate shows a
distinct and uniform increase in weight over that of the normal
control testes. The increase is on the average 14.2 per cent.
This is also shown in all the groups and ranges from 6.1 per
cent to 23.8 per cent. It is important to decide whether this
increase is represented by the germinal tissue or by the inter-
stitial tissue, or by both. It is generally held that the structure
which is responsible for the internal secretion of the testis is the
interstitial and not the germinal tissue. If this be true, and if
we assume that the increase in this instance is represented by the
interstitial tissue alone, then the percentage increase of the
latter structure will be considerably larger than that indicated

20

SHINKISHI HATAI

by the values given here. We shall take up this subject later on.
utilizing Hofmeister’s observations (’72) on the interstitial tissue
of the human testes.

Ductless glands

Thyroid gland. The thyroid gland of the semi-castrated shows
an average increase of 16.4 per cent above the controls. Here
again, as in the previous observations on the thyroid, the range
of variation is very great, being from — 37.3 per cent to 41.0 per
cent, and furthermore in the rats semi-castrated at 81 days, and
which will be described later, the thyroid shows 29.6 per cent
decrease instead of an increase. It is not therefore possible
at the moment to correlate the changes in the thyroid with this
operation

Suprarenal glands. The relative weight of the suprarenal
glands shows a slight alteration in the semi-castrated, giving an
average increase of 2.7 per cent in their favor. This low value
is due to an exceptionally small response given by group 5 ( — 0.9
per cent). If we neglect this exceptional case, the average rises
to 3.5 per cent. The increase in the semi-castrated is shown in
four out of five groups, and further the range of variation is not
so large, particularly if we neglect the very small value given by
group 5. Nevertheless, the increase is too slight to warrant us
in putting much weight upon it. However, some tendency to
an increase as the result of semi-castration can not be denied.

Thymus gland. Curiously enough, the thymus gland of the
semi-castrated rats shows an average decrease of 16.1 per cent.
The decrease occurs not only in the final average, but also in
four out of the five groups. The range of variation is not large
in comparison with the variations of the thymus glands belong-
ing in other series. It ranges from — 12.8 per cent to — 30.0 per
cent against the semi-castrated. On the other hand, we find in
the rats semi-castrated at 81 days 9.8 per cent increase of the
thymus — the exact opposite — and thus the interpretation is
at present impossible. This is the only instance in all the experi-
ments recorded in the present paper in which a decrease of the
thymus gland as the result of the operation has been found.

GROWTH AS AFFECTED BY GONADECTOMY

21

Hypophysis. The hypophysis shows an average increase of
10.1 per cent as the result of semi-castration. The range of
variation is great and lies between 0.5 per cent to 29.8 per cent.
Semi-castration at 81 days shows 0.25 per cent decrease, equiva-
lent to no change (see table 13). In view of this high variability
of, reaction all we can note is a tendency to overgrowth of the
hypophysis as one result of this operation.

Central nervous system

Brain weight. We find that the weights of the brain in the
controls and semi-castrated do not show any significant difference.
The average value gives — 0.5 per cent against the operated rats.
There is perhaps a very slight tendency to reduction in the brain
weight of the semi-castrated, as it occurs in four out of the five
groups. However, the difference is in many cases less than one
per cent and we thus conclude that semi-castration produces no
important alteration in the weight of the brain.

Spinal cord weight. The spinal cord of the semi-castrated
rats with respect to the body length is slightly but constantly
larger than that of the control rats. Its increase is shown in
all five groups and the final average shows 2.2 per cent in favor
of the semi-castrated. This agrees with the results of all the
experiments so far presented.

Percentage of water in the central nervous system. In this char-
acter the difference between the operated and control rats is
very small. We therefore conclude that the proportion of water
which is present in the central nervous system is not altered
by semi-castration.

AFTER SEMI-CASTRATION AT 81 DAYS OF AGE

The number of rats comprised in this series is rather small
(6 controls and 5 semi-castrated) but the results show a close
agreement with those rats from which one testis was removed
at 17 to 27 days. The data are presented in table 13. It is
only necessary to point out in this series also that the surviving
testis shows a typical increase in size. The increase is 15.1

22

SHINKISHI HATAI

per cent contrasted with 14.2 per cent for the previous series.
The alterations shown by the other characters are similar to
those found in the series operated at an earlier age, and therefore
we conclude that the effects of semi-castration at 81 days are
nearly the same as those found when the operation is made at
17 to 27 days, with the exception of the hypophysis, in which
the rats operated at the earlier period show a slight excess.

Parts of the encephalon

The parts of the encephalon of the semi-castrated rats have
been investigated. The technique and method of grouping are
the same as before (see page 10.) The rats employed for this
study were those semi-castrated at 17 to 27 days with their
controls. The results are given in table 14. As will be seen
from the table, there is no significant difference in the relative
weights of the parts of the encephalon in the control and the
semi-castrated. We therefore conclude that the relative weights
of the different parts of the encephalon are not modified by this
operation.

THE LIGATION OF THE SPERMATIC CORD

Since the removal of the testes produces striking modifications
in the external characters, as well as in some organs, and since
the removal of one testis alone does not produce any noticeable
alterations, presumably owing to the compensatory growth of
the interstitial tissues of the surviving testis, it was thought
interesting to determine the effect of ligation of the spermatic
cord, an operation which interrupts not only the vas deferens
but also the accompanying vessels and nerves. Although
this operation leaves the testes in place, not only may
their growth be stopped, but they may undergo various atro-
phies or degenerative changes as a consequence of it. The
operation was made on a small number of rats; 6 operated and
6 controls. The results are shown in table 15. The operated
animals were allowed to live a little more than three months.
Examination of results reveals the fact that we must treat the

GROWTH AS AFFECTED BY GONADECTOMY

23

data in two groups : Group 1 comprises those operated rats
whose testes, though typical in form, are yet small, pale in color,
semi-transparent and filled with an abundance of liquid. Thus
group 1 shows an abnormal condition of the testes, though
their form was normal. Group 2 comprises those operated rats
whose testes have been nearly completely absorbed.

Group 1. In this group the testes of the operated rats show a
decrease of 31.6 per cent, nevertheless the typical form was still
maintained. Although no histological examinations have as yet
been made, it appeared to me that the germinal tissues were
probably completely absorbed, or at least altered beyond recog-
nition. As will be seen from table 15, the characters usually
affected by castration were not noticeably modified. This
negative result suggests that the interstitial cells of the testes
were very likely intact or might even have proliferated.

Group 2. On the other hand, in those operated rats whose
testes have been nearly completely absorbed ( — 93.2 per cent)
alterations characteristic of the castrated rats are plainly to be
observed. A slightly longer tail, larger suprarenal glands,
thymus and hypophysis, definitely supports this conclusion.
We conclude, therefore, that ligation of the spermatic cord is
similar to castration in the reactions which it causes, if the testes
are absorbed, but its reaction is negative if the testes persist,
even though they may be materially reduced in size. Under
these conditions it is inferred that the germinal tissue has been
destroyed, while the interstitial tissue remains either in its
normal quantity or possibly is hypertrophied.

SEMI-SPAYING OF THE ALBINO RAT
AFTER SEMI-SPAYING AT 38 TO 51 DAYS OF AGE

This experiment comprises a rather small number of rats, and
the discussion of the effects of the operation will be limited to
those characters only which showed undoubted alterations. The
agreement in the results betweeen the present series and that
previously studied (Hatai T3) is clear. The results are shown
in table 16.

24

SHINKISHI HATAI

In general, we may say that the semi-spayed show no signifi-
cant response except in the increased weight of the surviving
ovary. The large difference shown by the thyroid gland must
for the present be credited to its high variability. The slight
increase of the other ductless glands may be considered a general
reaction common to all operated rats. On the other hand, the
weight of the surviving ovary is most striking, showing an
average increase of 131.8 per cent. Thus the one ovary of the
semi-spayed weighs more than twice the normal ovary. In my
previous experiment the increase of the surviving ovary was
found to be 73.1 per cent; the present experiment thus gives
the greater increase. No explanation for the amount of increase
in the surviving ovary can be given at the moment, and we must
be content to call attention merely to the striking character
of the reaction.

The lengths arid weights of the long bones , together with their water
content , after semi-paying

The weights and lengths of these bones, together with their
content of water have been investigated. The technique used
is the same as that employed in the preceding cases. The
results are given in table 17. From the final averages in the
table we obtain the following relations:

BODY LENGTH TO AV.

BODY WEIGHT TO

WATER CONTENT IN

BONE LENGTH

BONE WEIGHT

PER CENT

Controls

1:0.140

1:0.0141

26.985

Semi-spayed

1:0.140

1:0.0128

26.977

From the above we find that the relation of the body length to
the bone length is identical in the operated and controls. The
ratio of the body weight to the bone weight is distinctly lower
in the semi-spayed rats. This is undoubtedly due to the emacia-
tion of the body weight of the control rats, as can be seen from
the relation given by the length and weight of the body. Thus
if we take the ratio between body length and bone weight, we

GROWTH AS AFFECTED BY GONADECTOMY

25

obtain 1:0.0126 in the case of the control and 1:0.0125 in the
case of the semi-spayed. It is therefore safe to conclude that as
compared with the controls, semi-spaying does not modify
the bones either in weight or in length with respect to the weight
and length of the body. We note also the practical identity in
the water content of the bones in semi-spayed and controls.

THE ISOLATION OF THE OVARIES

Since the complete removal of the ovaries alters seriously
several bodily characters and organs*, and since semi-spaying
does not produce any noticeable alterations, owing probably to
the compensatory growth of the surviving ovary, it was thought
interesting to determine the effect of the removal of the one ovary,
combined with a severance of the other ovary from the uterus.
This experiment has been made with a small number of rats and
the results are shown in table 18.

As will be seen from this table, the result of the operation is
not materially different from the case of the semi-spaying. No
significant alterations are produced in any characters except
the weight of the ovaries. We find here an average increase of
51.3 per cent in the surviving ovary. The amount of increase
is not so large as in the case of the semi-spayed just described.
The smaller alteration is to be expected, as of course the ovary
is in the first instance severed from its normal connections, — ■
blood supply, etc., and thus subjected to unfavorable conditions.
In some instances the ovary was enclosed in a capsule contain-
ing fluid, and these cases showed unmistakable signs of absorp-
tion, the color was pale and the lobulation wanting.

DOUBLE ISOLATION OF THE OVARIES

From the results just described, we should anticipate that the
isolation of both ovaries from the uterus would not be followed
by any marked alterations. It was thought best, however, to
test this assumption and therefore the following short experi-
ment has been made. The results are given in table 19.

26

SHINKISHI HATAI

As had been anticipated, no notable alterations were shown
as the result of the isolation of both ovaries. The responses
exhibited by the various characters are very small, and parti-
cularly when we consider the small number of rats in the series,
these modifications can all be neglected. We however note
with some interest a slight increase of the ovaries (14.0 per cent)
in the operated rats, but whether this increase is a consequence
of the operation or a mere fluctuation, cannot be decided without
more evidence.

GENERAL DISCUSSION OF THE RESULTS OF GONADECTOMY

So far I have merely presented my results without either
interpretation or comment, save in the case of the external
characters. I wish now to discuss these results and if possible
to interpret the alterations following gonadectomy.

For convenience I give in table 20 the percentage deviations
of the various characters in the operated rats from those in the
controls. The external characters, such as absolute body length
and body weight, and also body weight and tail length relative
to body length have been briefly considered in the case of each
series, and appear to be particularly related to changes in the
hypophysis. It is especially with the members of the endocrene
system, so far as we have examined them, that we are at present
concerned.

Thyroid gland. On the average the amount of deviation in
the weight of the thyroid gland of the operated from that of the
controls ranges from 34 per cent to —51 per cent (see table 20).
On account this high variability, as well as the absence of uni-
formity of response to the same operation, no definite conclusions
can be drawn from our results touching the effect of gonadectomy
on it. Turning to the literature, we find that Tandler and
Grosz (T3) observed constantly a small thyroid gland in eunuchs.
Biedl (’13) mentions finding a small thyroid in one castrated dog.
Soli (’09) found a considerable variation in the weight of the
thyroid in capons. Out of the nine pairs which he examined,
four showed an increase and five a decrease in the castrated

GROWTH AS AFFECTED BY GONADECTOMY

27

compared with the controls. Soli however found a constant
increase in the weight of the thyroid, in the castrated rabbits
(numbers are not given) when examined three months after
castration, but this in turn was followed by a decrease, so that
at the end of the experiment the castrated rabbits had smaller
thyroids than the controls. Engelhorn (’12), on the other hand,
found an hypertrophy of the thyroid after spaying in women and
in rabbits. Thus, so far as the previous investigations are
concerned, the effect of gonadectomy on the size of the thyroid
is not determined.

In view of the great variability of the thyroid in weight in
both men and animals, and in view of the small number of ani-
mals used by most investigators and the almost complete ab-
sence of data for the normal animal, as well as the inconstancy
of our own results on the albino rat, we conclude that no general
statement as to the effect of gonadectomy on the thyroid is justi-
fied at present.

The thyroid gland of the albino rat presents, however, several
interesting features worthy of remark. I have determined
(Hatai T3a) that the hypophysis and the suprarenals of the
albino rat show distinct sexual differences in their weights. The
thyroid gland, however, does not show any sex difference in weight.
Moreover, for any given body weight, the weight of the thyroid
is practically identical in the (domesticated) albinos and (the
wild) norway rats, while the other ductless glands show distinct
weight differences in these two forms. Thus in the albino the
thyroid glands shows no response to the changes in the surround-
ings (domestication) nor variations according to the sex similar
to some other ductless glands.

Whether the thyroid of the rat is physiologically less important
than some of the other ductless glands cannot be decided from
such simple observations, nevertheless it is of interest to note
that the ill effects of thyroidectomy in the rat are remarkably
slight (see Vincent ’12). One might suspect that the high
variability of the thyroid gland was due in part to pregnancy
in the females. I have examined my data with this idea in mind,
but have failed to find any correlation between pregnancy and

28

SHINKISHI HATAI

thyroid weight. As a matter of fact, the variability of the gland
is as large in the males as in the females.

Suprarenal glands. The effects of gonadectomy on the size
of the suprarenal glands have been studied by several investi-
gators. Feodossiew (’06) found an enlargement of the suprare-
nals in spayed dogs. Von Schenk (TO) found histological evi-
dence of hyperfunction of the gland in spayed rabbits. He
further noted an enlargement of the gland as indicated by the
fact that the areas of the sections in the operated are greater
than those of the controls. Von Schenk, however, did not record
any weights. .Marrassini and Luciani (Tl) noted in spayed
guinea-pigs and rabbits an enlargement of the suprarenals.

As the result of castration, Soli (T9) found a diminution of
the suprarenals in the chicks, and in guinea-pigs and rabbits.
In the latter however the suprarenals soon after operation showed
a very slight increase which was followed by a distinct diminution
in a latter stage. Marassini and Luciani (Tl) on the other hand
found a considerable increase in castrated rabbits and in guinea-
pigs when compared with their respective controls. Stilling
(’98) found an enlargement of adrenals in male rabbits during
the breeding season. Kolmer (TO) who studied the histology
of the suprarenal glands of guinea-pigs, shows clearly an inti-
mate relation between the sex glands and the suprarenals. He
states that there exist definite cyclical changes of the suprarenals
following corresponding changes of the sex glands in functional
activity.

It is evident from this that the suprarenal glands are intimately
related to the sex glands, both in males and in females. My own
investigations also show clearly such relations between the two
sets of glands in the rats; i.e., the suprarenal glands exhibit
characteristic alterations after gonadectomy. It has been found
that the suprarenal glands of the castrated rats exhibit an in-
crease of 8.5 per cent to 17.6 per cent on the average, while those
of the spayed rats show a decrease of 5.3 per cent to 25.0 per
cent compared with their respective controls. These variations
in the reaction in the two sexes are very regular and occur in
all series and in most groups in each series. Why* the suprarenals

GROWTH AS AFFECTED BY GONADECTOMY

29

respond differently in the two sexes as the result of gonadectomy
cannot be explained at present, and we therefore merely note
this singular phenomenon. There are no other corresponding
observations on rats in the literature, so that our results must be
compared with those obtained from other animals.

It is interesting to note, as previously stated, that Soli (’09)
records a reduction of the suprarenals as the result of castration,
while Marrassini and Luciani (Tl) using the same species of
animals, noted an increase. These diametrically opposed results
may mean that the individual variation of the suprarenals is
greater than that produced by castration, or that the suprarenals
may not respond similarly at different seasons, or in the presence
of different diets. As will be seen later, these investigators
obtained after castration opposite results for the size of the
hypophysis also. We must therefore await the results of further
experiments with a much larger number of animals belonging
to the species studied, maintained under very definite nutritive
conditions, before endeavoring to reach a conclusion.

In this connection it is important to point out once more
that the size of the suprarenal glands in rats differs strikingly
according to sex (Hatai T3). The female rats have considerably
larger glands than the males. This sexual difference is evident
prior to sexual maturity. Gonadectomy in the male increases
the weight of the suprarenals at the same time that gonadectomy
in the female reduces the weight, thus bringing the two sexes
nearer together in this character. Moreover, we notice in several
other instances after gonadectomy, the similar phenomenon of
the approach of characters which are differently modified in the
normal rat according to sex. The weights of the suprarenals
are not altered to any noticeable extent by partial gonadectomy,
either in the males or the females.

Thymus. The effect of gonadectomy on the size of the thymus
has been studied by numerous investigators. Calzolari (’98)
found the thymus in the castrated rabbits strikingly enlarged.
He considers that the normal atrophy of the thymus is delayed
by the removal of the testes. Henderson (’04) obtained similar
results in rabbits, guinea-pigs and cattle. Goodall (’04) noted

30

SHINKISHI HATAI

also an enlarged thymus in castrated guinea-pigs. Hammer
(’05) and Tandler and Grosz (’07) found the thymus enlarged
in eunuchs. Further, Soli found the same (’09) in chicks and
rabbits; Marrassini (’10) in chickens, and Gellin (’10) in both
sexes of rabbits obtained similar results. Still other investi-
gators have noted the hypertrophy of the thymus after gonadec-
tomy and their papers are cited in the works of Biedl (’13) and
of Vincent (’12), to which the reader is referred.

It is clear, therefore, that all the investigators agree that gon-
adectomy increases the size of the thymus in both sexes. As
can be seen from table (20), my own investigations on albino
rats are in full accord with this result. The weight of the thymus
after gonadectomy is almost twice that in the control rats, and
furthermore the enlargement occurs in all the series with the
exception of the semi-castration series at 17-27 days in which
series the reaction is anomalous. We further note that gonadec-
tomy in young animals not only enlarges the thymus and delays
its normal involutionary process, but that the gland responds
even after it has atrophied to a considerable extent. The experi-
ments upon the rats whose ages were about 200 days show this
clearly (pp. 9 and 17). Although we have not examined histo-
logically the normal thymus at 200 days, nevertheless its gross
appearance shows that much of the mass is represented by
connective tissue. Yet even in such a highly atrophic stage,
the thymus can respond nearly as well as when gonadectomy
has been performed at a much earlier age.

Hypophysis. The alterations in the size of the hypophysis
following gonadectomy have been much studied and we are there-
fore in a position to discuss these alterations somewhat fully.

Fichera (’05) has shown that the removal of the testes in fowl
and cattle enlarges the hypophysis. He also has shown that
spaying produces similar enlargement of the hypophysis in rabbits
and guinea-pigs. Fichera considers this hypertrophy of the
hypophysis as a physiological compensation, supplementing
the loss of the sex glands. Fichera’s observations were confirmed
by numerous investigators using not only the same species, but
also several other kinds of animals. We shall cite only a few of

GROWTH AS AFFECTED BY GONADECTOMY

31

the investigators whose work seems most closely related to our
own, and for the full bibliography refer the reader to the works
of Biedl (’13) and Vincent (’12). Enlargement of the hypophysis
has been reported by Parhon and Goldstein (’05) in spayed rabbits
and dogs; by Cimoroni (’08) in castrated rabbits and dogs;
by Kon (’09) and by Tandler and Grosz (’10) in both men and
women; by Hatai (’12) in castrated rats; by Zacherl (cited by
Biedl ’13) in both male and female rats; and by Soli (’09) in
castrated fowls and rabbits. Livingston (’14) finds an enlarged
hypophysis in spayed rabbits, but not in castrated. Lastly,
this present experiment gives again an instance of enlarged
hypophysis in the male albino rat after castration (table 2, 3 and
4) while spaying also is followed by an increase, which, however,
is only slight.

At the same time, there is an almost equally numerous group
of investigators who have not found an enlargement of the
hypophysis after gonadectomy. For instance, Pirsche (’02)
did not obtain any enlargement of the hypophysis from castrated
guinea-pigs, but at the same time he found a noticeable increase
in the body weight. At autopsy he did not notice any unusual
deposition of fat. Barnabo (’08) failed to find an enlargement
of the hypophysis in castrated albino rats, though he found an
enlargement in a rat, one testis of which had been removed and
the vas deferens of the other testis ligated. Marrassini and
Luciani (’ll) using fowls, cattle, guinea-pigs and rabbits (the
kinds of animals used by Fichera) failed to notice an hypertrophy
of hypophysis, though they noted the enlarged suprarenal glands.
Hatai (’13) noticed in the spayed albino rats an increase of the
hypophysis which was small as compared with that following cas-
tration. Livingston (’14) in a large number of rabbits failed to
find an enlargement of the hypophysis in the castrated males, but
noted an overgrowth of the body in weight. In the spayed female
rabbits, however, Livingston found a noticeable degree of hyper-
trophy of the hypophysis, but failed to obtain an overgrowth
in body weight. Lastly, my own present experiment fully con-
firms the findings of the previous experiment: that is, in the cas-
trated rats the hypophysis enlarges very strikingly, while the

32

SHINKISHI HATAI

growth of the body is nearly normal. On the other hand, in the
spayed rats the hypophysis shows only an insignificant increase,
but this is accompanied by greater growth, both in body weight
and in body length.

I have mentioned already the experiments of Barnabo and of
Zacherl, both of whom used albino rats. Since my own obser-
vations are based entirely on gonadectomized albino rats, and
since the foregoing is the only work with which our own can be
directly compared, it will be worth while to review in some detail
the results obtained by these two investigators.

Barnabo’s (’08) experiments were as follows:

Series 1. Bilateral section of vas deferens. This series com-
prises three rats.

Series 2. Section of vas deferens on one side and castration
on other. This series comprises two rats.

Series 3. Bilateral castration. This series comprises three
rats.

Barnabo’s operations were performed on sexually mature
rats (112 grams in average body weight) and the period between
operation and death was on the average 76 days. As long as
we have made no experiments corresponding to Barnabo’s
Series 1 and 2, we shall pass them by and consider only the results
obtained from his Series 3. There we find the average weight
of the hypophysis as reported by him was 0.015 grams in rats
with a final body weight of 151 grams. Barnabo concludes that
the weight of the hypophysis is not altered as the result of
castration. No data are given regarding the control rats, and it is
merely stated “Per altro controllo mi sono poi servito di animali
normali.” However, according to our formula (Hatai T3)
the weight of the hypophysis given by Barnabo is almost 150
per cent heavier than it ought to be for the body weight given.
For this peculiar result no satisfactory explanation can be given,
but I venture to suggest that it is just possible that Barnabo
did not realize the existence of the striking sex difference in the
weight of the hypophysis, and by an oversight compared the
weight of the hypophysis in the castrated rats with that in normal
females, in which case but slight difference might appear, as at

GROWTH AS AFFECTED BY GONADECTOMY

33

this period the weight of the hypophysis in the female is more
than twice that in the male (Hatai T3). In any case, the number
of rats used by Barnabo is certainly too small to furnish the basis
for any definite conclusion.

Concerning ZacherFs work, we have too little information for
criticism. The following is BiedFs (T3) statement concerning
ZacherFs work: “Bei Ratten tritt nach der Kastration, wie aus
den Versuchen, welche Dr. Zacherl in unserem Institute ausge-
ftihrt hat, hervorgeht, konstant eine Volumzunahme der Hypo-
physe ein, u. zw. sowohl bei mannlichen, wie bei weiblichen
Tieren.” Nothing is given regarding the number of rats used
for either control or operation and no numerical data concerning
the weight of the hypophysis are given, so that the extent of
the alteration cannot be determined.

So far as I am aware, these are all the statements we have re-
garding the effect of gonadectomy in the albino rat on the weight
of the hypophysis, and for reasons already given, we must await
further work before explaining the differences between the results
of Barnabo on the one hand and those of Zacherl and ourselves
on the other.

The brief review of the literature given above reveals the
fact that the findings as to the effect of gonadectomy on the
size of the hypophysis are diametrically opposed to each other.
Probably the contradictory results obtained may be traced to
one or more of three causes:

(1) Insufficiency in the number of animals used.

(2) Variations in the weight of the hypophysis arising from

confusion of the sexes or from the use of different litters, or still
more from the use of different strains of the same race. i

(3) True variations in the response of the hypophysis associated
with differences in the reponse of the body to gonadectomy.

The first two suggestions have been discussed in my previous
paper (Hatai T3) and I will therefore limit my comments here
to the third cause named.

It is highly probable that the hypophysis may not respond
always in the same manner, but vary in its response according
to the condition of some other parts of the body. For instance,

THE JOURNAL OP EXPERIMENTAL ZOOLOGY, VOL. 18, NO. 1

34

SHINKISHI HATAI

I have often noted that some spayed rats presented a considerable
increase in the weight of the hypophysis when these animals
failed to show any overgrowth and obesity. The reaction of
the hypophysis in this instance is similar to that in the castrated
rats. Similarly, the castrated rats give a very slight or practically
no increase in the weight of the hypophysis, when these show,
as they sometimes do, a marked obesity. In this case the re-
action of the hypophysis is much the same as that of the typical
spayed rats. Such instances are not at all infrequent. In
fact, in the series here described all the female rats whose ovaries
were removed gave much greater increase in the weight of the
hypophysis than those belonging to the previous series (Hatai
T3). The difference in the response in the two series is explained
by the fact that the spayed rats belonging to the earlier experi-
ment (1912 series) showed considerable obesity, while those
belonging to the present series did not, although the body had
gained both in weight and in length. It seems therefore probable
that the size of the hypophysis and body changes, especially fat
deposition, are inversely related.

The evidence just given suggests that the contradictory
findings by various observers may be due in part to these differ-
ences in response shown by the body as a whole, or by some
of the other ductless glands. It is probable therefore that if
the three conditions mentioned above were carefully regarded
we might in the future obtain more harmonious results. Since
this survey indicates that the weight of the hypophysis and of
the body are reciprocally related, I wish to show how far this
suggestion may be used to explain some discrepancies already
found in the literature.

We have noted that Pirsche (’02) found an overgrowth of the
body in weight in the castrated guinea pigs, but did not find the
enlargement of the hypophysis. Pirsche’s observation is certainly
contrary to the observation of Fichera (’05) who found an en-
larged hypophysis, but possibly the discrepancy may be traced
to the different reactions of the body in weight. Unfortunately
Fichera does not give us any information regarding the growth
of the body and thus we are unable to test the point in this case.

GROWTH AS AFFECTED BY GONADECTOMY

35

However, Livingston’s (’14) experiments on rabbits demon-
strate the reciprocal relation in the weight of the hypophysis
and of the body, and thus it appears probable that different
results obtained by others who also used rabbits, may be traced
to the differences in the response of the body. There seems to
be analogous variations in the case of the other ductless glands.
Paton (T3) gives the following instance of a typical response
of the testes after thymectomy in guinea-pigs:

When studying the action of testes and thymus on growth, I found
that one guinea pig in my series, after removal of the thymus, hardly
grew at all, although remaining quite well and active. When it died
at over four months old, it was like an animal about a fortnight old,
and the testes were in size and structure those of an animal of the same
age. They had undergone no compensatory hypertrophy, as they
usually do, and the result had apparently been arrest of growth which
occurs when thymus and testes are removed together.

I have shown elsewhere (Hatai ’13) that in albino rats the
hypophysis of the female is more than twice as heavy as that of
the male. This sexual difference is evident prior to sexual
maturity. Our present observations show this sexual difference
to exist in the norway rats, although it is slight in amount.
Whether or no a sexual difference exists in other mammals has
still to be determined. Whatever may be the true function of
the hypophysis and its relation to the body, we have interesting
quantitative relations between the size of the hypophysis and
size of the body. The clinical as well as the experimental evi-
dence (Cushing ’09, and Vincent ’12) shows with a high degree
of probability that ‘hyposecretion’ of the hypophysis produces
an abnormal deposit of fat and a tendency to gigantism. Thus
if a compensatory growth of the hypophysis does not follow,
as is the case after spaying, the product of the unaltered gland
must be employed for two purposes, one to replace the ovarian
hormone, and two, for the normal uses, whatever these may be.
Spaying thus appears to overtax the unmodified gland, and
consequently to produce phenomena similar to those following
hyposecretion. On the other hand, compensatory hypertrophy
of the hypophysis in the male albino rats after castration appears

36

SHINKISHI HATAI

to prevent the phenomena of hyposecretion, and consequently
the body changes are absent. The typical cases mentioned
above may be interpreted on the same principle. The results
of semi-spaying and of semi-castration in the albino rat gives
still further evidence in support of the view just presented.
Partial gonadectomy produces neither an enlargement of the
hypophysis, nor abnormal fat deposition in the body. This is
explained by the fact that the remaining sex gland undergoes a
compensatory hypertrophy, and thus the normal secretory
function is performed adequately.

Ovaries. A compensatory hypertrophy of the surviving ovary
after semi-spaying has been noted by several investigators.
Bond (’06), Carmichael and Marshall (’08) and Fichera (’10)
all reported this in semi-spayed rabbits. In my previous paper
(Hatai T3) I have also shown the compensatory hypertrophy of
the remaining ovary in the semi-spayed albino rat. The present
investigation confirms the previous results, and indeed the semi-
spayed rats of the present series give a surviving ovary of more
than twice the normal size. This compensatory growth of the
ovary evidently prevents all body changes after semi-spaying, as
I have not been able to find any noticeable alterations in the
other characters examined. I have not made any histological
examination to determine exactly what tissue is responsible for
this enlargement of the ovary. However it is probable that
this increase is caused by the overgrowth of the interstitial cells
rather than of the germinal or follicular cells. This statement
is based on the results of transplanting ovaries into spayed
animals. It has been noted by numerous investigators that
when the ovaries are thus transplanted all the structures except
the interstitial cells undergo degenerative changes, yet even when
so modified, the transplanted ovary is capable of preventing the
typical reactions of ovariotomy. Steinach (’12) demonstrated
that the interstitial tissue alone is sufficient to produce feminine
traits in the castrated albino rats to which the ovaries were
transplanted.

Testes. So far as I am aware, an enlargement of the surviv-
ing testis following semi-castration has not yet been reported.

GROWTH AS AFFECTED BY GONADECTOMY

37

Failure to observe this response is probably due to the lack of good
reference data such as we possess in our laboratory records, and
which are necessary to reveal such a change. It has been stated
that the testis of the semi-castrated rat shows an increase of
14 to 15 per cent. This increase though small, is highly uniform
and occurs in all the series.

I have shown that in the case of the semi-spayed rats the com-
pensatory hypertrophy of the surviving ovary is nearly perfect,
and that probably it is the interstitial tissue which increases.
Let us see whether the same reaction is possibly occurring in
the case of the testes.

Bouin and Ancel (’03 and ’04) have brought evidence to show
that it is the interstitial cells which are essential for inhibiting
the characteristic alterations after castration. They removed
one testis in the rabbit and ligated the vas deferens of the other.
After ten to twelve months they found a marked hypertrophy
of the interstitial cells. They found also that some rabbits,
after ligature of the vas deferens, developed characters which
follow castration, and they believed that this occurred when nerve
as well as the duct was ligated. Vincent and Coleman (cited by
Paton T3) found that ligature of the whole spermatic cord, with
blood vessels, acts in the same way as castration. On ligating
the spermatic cord in rats, I have found the phenomena similar
to those reported by Vincent and Coleman. When after this
operation the entire testes, including the interstitial cells, de-
generate, then the animal manifests the castration reaction.
However, if the testes manage to survive partially, though all
the germinal cells are degenerated, the rats do not exhibit the
castration reaction. From this it seems reasonable to infer
that the increase of the remaining testis after the removal of the
other must be due to hyperplasia of the interstitial cells. If
this inference is correct, the increase of the interstitial tissue
though absolutely slight in comparison with the entire testes
(for it is only a small fraction of the normal testes), should be
relatively large when referred to itself as a standard. Un-
fortunately we have no data for the rat bearing directly on the
normal amount of interstitial tissue in the testes. There are,

38

SHINKISHI HATAI

however, some observations on man. Hofmeister (’72) estimates
in the human testes at the fourth month the amount of the inter-
stitial tissue to be two-thirds of the whole testes. At eight
years of age it constitutes only one-tenth of the organ, but at
puberty it again increases somewhat. Taking Hofmeister’s esti-
mate of one-tenth of the whole testis for the interstitial tissue as
applicable to the adult albino rat, we find the following interest-
ing relations: From table 12 it appears that the average weight,
of both testes is 2.329 grams for body length of 217 mm. in the
control rat, and the weight of the single testis of the semi-castrated
is 1.239 grams for a body length of 209 mm. Since the weight
of the testes increases with increasing body length, the weight
of the testes of the control and of the experimented cannot be
directly compared until the difference for the body lengths in the
two forms is adjusted. When this correction is made according
to the formula (Hatai ’13) we find that the one testis of the con-
trol is 14 per cent less in weight than the single testis of the
semi-castrated. We have assumed that the amount of the inter-
stitial tissue is one tenth of the whole testis, accordingly we find
the interstitial tissue to be 0.117 grams for the control and 0.124
grams for the semi-castrated. To this latter value 14 per cent
of the weight of the single testis of the control ( = .163) must be
added to give the assumed value of the interstitial tissue of the
semi-castrated. We thus obtain 0.287 grams of interstitial
tissue for the single testis of the semi-castrated against 0.117
grams for one testis or 0.233 for both testes of the controls.
Thus if we apply the increase of 14 per cent in the entire test is
to the interstitial tissue alone, the increase of this latter amounts
to over 100 per cent above that of the control. This result
depends of course entirely on the correctness of assumption that
one-tenth of the whole testes in the albino rats consists of inter-
stitial tissue. Although direct proof of this is lacking, the
assumption seems to have some evidence in its favor and none
against it. Thus the increase of 14 per cent in the testis as a
whole after semi-castration is misleading, for in all probability
it really means a doubling in the amount of the interstitial tissue;

GROWTH AS AFFECTED BY GONADECTOMY

39

a response almost as complete as that shown by the ovary after
semi-spaying.

Skeletal system. Alterations of the bones in weight and in
length after gonadectomy have been reported by a number of
investigators. Poncet (’97) reported upon rabbits in which he
found that castration produces stronger and especially longer
bones. Pirsche (’02) found also stronger and longer bones in
castrated guinea-pigs. Sellheim (’99) found similar phenomena
in the castrated dog. With eunuchs Tandler and Grosz (’13)
found constantly longer bones. Without giving any further
evidence, it is safe to say that gonadectomy according to these
investigators causes an abnormal elongation, and occasionally
a thickening of the bones.

In my experiments on albino rats, I have found that the ratio
between body weight and bone weight and the ratio between
body length and bone length tend to be slightly higher in the
gonadectomized rats than in the controls. The alteration, though
constant, is certainly very slight, and indeed the difference
between the control and experimented becomes evident only
after careful computation. On the other hand, one gets the
impression that the skeletal changes reported by other investi-
gators were so large that they could be detected at a glance.

Corresponding data on rats obtained by other investigators
are not available for comparison, and thus I am unable to say
whether the slight alteration of the bones in weight and length
are to be regarded as typical for the albino rat after gonadectomy.
However, the water content of the bones was distinctly higher
in the gonadectomized rats. At the present moment the inter-
pretation of this phenomenon is not clear. In the semi-castrated
rats, there was no alteration either in length, weight or in the
amount of water in the bones.

In this connection it may be interesting to note that the tail
length of the castrated is noticeably longer than that of the con-
trol rat. The difference amounts to 3.2 per cent to 4.7 per
cent in the rats which have been operated on at 19 days and 86
days respectively. The rats castrated at 220 days gave a dif-

40

SHINKISHI HATAI

ference of 1.8 per cent. On the other hand, the spayed rats do not
give this response. To interpret this response will require
further experiment, but in the mean time the fact of this occur-
rence is worthy of note.

Central nervous system

Gonadectomy is apparently without influence on the central
nervous system. The proportional weights of the different
parts of the brain and the percentage of water in the several
divisions of the system are unmodified, while the slight alter-
ations in the absolute weights of the brain and spinal cord are,
by reason of their lack of uniformity, most readily explained as
fluctuation. This result is one of prime importance from the
standpoint of our general laboratory problem — the growth of
the mammalian nervous system — for it shows that after 15 days
of age, gonadectomy, complete or partial, is without influence
on the gross structure or fundamental chemical make-up (water
and solids) of the nervous system. Further, as the behavior
of the female can be induced in the male by the implantation
of ovarian tissue (Steinach T2) and the characteristic male
behavior ceases after castration, we obtain good evidence for
the view already put forward by Steinach that the respective
gonads are activators of the nervous system according to sex,
and in addition we now have evidence that this is accomplished
without recognizable changes in either the structure or the
fundamental make-up of the system.

Secondary sexual characters

Recently Steinach (TO, T2) has made a careful study of these
in the albino rat and noted modifications in size of the secondary
sex glands, nipples and bones, the changes in hair and in behavior.
To the list of modifiable characters which Steinach has given, I
am able to make the following additions: The hypophysis of
the normal male rat is considerably smaller than that of the female.
Castration increases the weight of the hypophysis thus making
ti approach that of the female. The suprarenals of the male

GROWTH AS AFFECTED BY GONADECTOMY

41

are normally smaller than those of the females. Again castration
increases the male suprarenals. At the same time, spaying
reduces the suprarenals of the female, thus causing the two sexes
to approach each other in this character. Further, we have
found that the tail of the normal male is definitely shorter than
that of the normal female. Castration increases the tail length
of the male — thus approximating the relation in the female.
Again, the body of the adult female is much smaller both in length
and weight than that of the adult male. Spaying induces an
overgrowth of the female body both in length and in weight,
while castration tends to make the male body somewhat less
than normal, thus bringing the two sexes nearer together. Speak-
ing very generally, we might say that gonadectomy tends to
produce the secondary characters found in the opposite sex.

SUMMARY

All the experiments were made on albino rats. There were
five series, representing five different operations:

1. Total gonadectomy: castration and spaying.

2. Partial gonadectomy: semi-castration and semi-spaying.

3. Ligation of spermatic cord.

4. Removal of one ovary, followed by an isolation of the other
ovary from the uterus.

5. The isolation of both ovaries from the uterus.

The following body characters and organs (or some of them)
were measured in each series: Body length, body weight, tail
length, sex glands, thyroid, suprarenals, thymus, hypophysis,
various long bones and the central nervous system. The main
results are given under the characters studied.

( 1 ) Body length. Comparing the operated animals with the
controls, the absolute body lengths were found to be slightly
less in all the operated rats except the spayed females in which
the body lengths were distinctly greater.

(2) Tail length. The tail with respect to the body length
tends to be slightly longer in the castrated males, but no signi-
ficant alterations occur in the other series.

42

SHINKISHI HATAI

(3) Body weight. The body weight in respect to body length
is greater in nearly all operated rats, but especially is this the
case in the spayed rats.

(4) Weight and length of the bones. These characters are not
modified in the semi-spayed rat, but in the castrated as well as
in spayed rats, the bones (femur, tibia and fibula; humerus,
radius and ulna) tend to be very slightly longer and heavier
than in the corresponding controls. The bones were not ex-
amined in the other series. The percentage of water in the bones
is also slightly higher in the operated than in the controls. No
alteration was noted in the semi-spayed in this respect.

(5) Central nervous system. No characteristic response can
be reported for the central nervous system. The differences
in total weight after gonadectomy appear to be fluctuations
merely. The different parts of the brain were not modified in
their relative weights, and the water content of the brain and
of the spinal cord were the same in both the operated and in the
controls.

(6) Sex glands. In the semi-spayed series the compensatory
growth of the remaining ovary is almost perfect as it attains
nearly twice its normal size. In the case of the semi-castrated
series the remaining testis shows an increase of 14 per cent as a
whole. If however we assume that the increase is due solely to
hyperplasia of the interstitial tissue, and further, if we take
Hofmeister’s estimate of the interstitial tissue as one tenth of
the entire testes in the human testes and apply it to the rat, we
obtain compensatory growth in the interstitial tissue in the semi-
castrated rat which is almost as great as in the case of the re-
maining ovary of the semi-spayed rat. The isolated ovaries
survived and grew as if these had been connected with the
uterus. In the case of isolation of the ovary followed by semi-
spaying, the remaining isolated ovary hypertrophies in the same
manner as that of the semi-spayed rat. The ligation of the
spermatic cord in certain cases causes a complete atrophy of
the testes, thus producing the alterations of the body characters
similar to those which appear in the castrated rats.

GROWTH AS AFFECTED BY GONADECTOMY

43

(7) Thyroid gland. On account of its great variability in
weight, no definite conclusions can be drawn from the variations
observed in the weight of the thyroid gland.

(8) Suprarenal glands . The suprarenal glands show opposite
reactions in the two sexes as the result of gonadectomy. In
the castrates, the suprarenals show an increase, and in the spayed
rats, a decrease. No adequate explanation can be given for
this singular phenomenon. The suprarenal glands fail to give
any response in all the other experiments, except those where
the spermatic cords were ligated. In these last the suprarenals
show reactions similar to those which follow castration in group
II where the testes has been absorbed.

(9) Thymus. The thymus gland shows a very striking re-
sponse to gonadectomy, though no noticeable alterations were
found to follow partial gonadectomy. After the former opera-
tion the thymus increases to almost twice tlje size which it has
in the control rats. The thymus seems not only to delay its
normal involutionary process but actually to increase in weight
as the result of gonadectomy. Gonadectomy enables the thymus
of the old rat to respond, and thus a highly atrophied thymus
may become enlarged almost as much as if the operation were
performed on young animals.

(10) Hypophysis. Following the removal of the testes, the
weight of the hypophysis is increased on the average as much as
50 per cent. On the other hand, spaying produced only a slight
increase (about 8 per cent on the average). This difference in
reaction according to sex has been noted in my previous experi-
ments (1912 series). All the other series show an almost insigni-
ficant variation, except the ligation of the spermatic cord which,
when followed by absorption of the testis, gives a response similar
to castration.

(11) Relations of the hypophysis to the growth of gonadectomized
rats. After removal of the sex glands, it appears that when
compensatory growth of the hypophysis occurs, there is no over-
growth of the body or obesity. On the other hand, both these
latter responses appear when the enlargement does not occur — as

44

SHINKISHI HATAI

in the spayed rats, for example. In the semi-spayed, as well as
in the semi-castrated, neither enlargement of the hypophysis nor
overgrowth and obesity occur, because the enlargement of the
remaining ovary or testis enables the surviving sex gland to
furnish the normal amount of gonadine.

(12) Secondary sexual characters. The total removal of the
sex glands tends to increase the resemblance between the two
sexes, or, in other words, to reduce the differences in those second-
ary characters which, in the normal animal, are marks of sex.
Put in another way, we may say with equal truth that gonadec-
tomy in a given sex tends to produce’ the secondary characters
found in the opposite sex.

LITERATURE CITED

Barnabo, V. 1908 Sui rapporti tra la glandola interstiziale del testicolo e le
glandole a secrezione interna. 11 Policlinico, tom. 15.

Bond, C. J. 1906 Some points in uterine and ovarian physiology and pathology
in rabbits. British Med. Jour., vol. 2.

1906 The by-effects of hysterectomy and oophorectomy. British
Med. Jour., vol. 2.

Biedl, A. 1913 Innere Sekretion. 2nd edition. Urban and Schwarzenberg.
Berlin.

Bouin, P., and Ancel, P. 1903 Recherches sur les cellules interstitielles du
testicule des mammiferes. Arch, de Zool. Exper., tom. 1, 4th series.
1904 Recherches sur la signification phys. de la glande interstitielle
du testicule des mammiferes. Journ. de phys. et de path, gen., vol 6.
Calzolari, A. 1898 Recherches experim. sur un rapport probable entre la
fonction du thymus et celle de testicule. Arch, it/al. de biol., tom. 30.
Carmichael, E. S., and Marshall, F. H. A. 1908 On the occurrence of com-
pensatory hypertrophy in the ovary. Jour, of Physiol., vol. 36.
Cimoroni, A. 1907 Sull’ipertrophia dell’ipofisi cerebrale negli animali stiroi-
dati. Lo Sperimentale, tom. 61, and Arch. Ital. de Biol., tom. 48.
Cushing, H. 1909 The hypophysis cerebri. Clinical aspect of hyperpituitarism
and of hypopituitarism. Jour. Amer. Med. Assoc., vol. 53.
Donaldson, H. IP., and Hatai, S. 1911 Note on the influence of castration on
the weight of the brain and spinal cord in the albino rat and on the
percentage of water in them. Jour. Comp. Neur., vol. 21.
Engelhorn, E. 1912 Schilddruse und weibliche Geschlechtsorgane. Sitz.

der phys.-med. Sozietat in Erlangen, Bd. 43.

Feodossiew, N. E. 1906 Hypertrophie der Nebennieren nach Entfernung
der Eierstocke. Russkij Wratch, vol. 5.

I

GROWTH AS AFFECTED BY GONADECTOMY

45

Fichera, G. 1905 Sur l’hypertrophie de la glande pituitaire consecutive a la
castration. Arch. Ital. de Biol., tom. 43.

1910 Recherches experimentales sur les processus de reparation et
de compensation a la suite d’une intervention sur l’ovarie. Arch. Ital.
de Biol., tom. 53.

Gellin, O. 1910 Die Thymus nach Extirpation, bzw. Rontgenbestrahlung
der Geschlechtsdriisen. Zeitschr. f. exper. Path. u. Ther., Bd. 8, no. 1.

Goodall, A. 1904 The postnatal changes in the thymus of guinea pigs and the
effect of castration on thymus structure. Jour. Physiol., vol. 32.

Hammar, J. A. 1905 fiber Thymusgewicht und Thymuspersistenz beim Mensch-
en. Verhandlungen der Anat. Gesellschaft.

Hatai, S. 1913 On the weights of the abdominal and thoracic viscera, the
sex glands and the eyeballs of the albino rat (Mus norvegicus albinus)
according to body weight. Am. Jour. Anat., vol. 15.

1913 a The effect of castration, spaying or semi-spaying on the weight
of the central nervous system and of the hypophysis of the albino rat ;
also on the remaining ovary. Jour. Exp. Zool., vol. 15.

1914 On the weight of the thymus gland of the albino rat (Mus nor-
vegicus albinus) according to age. Am. Jour. Anat., vol. 16.

Henderson, J. 1904 On the relationship of the thymus to the sexual organs.
Jour, of Physiol., vol. 31.

Hofmeister, F. 1872 Untersuchungen liber die Zwischensubstanz im Hoden
der Saugetiere. Sitz. der math.-naturwiss. Klasse der K. K. Akad.
der Wissenschaften, Wien. Bd. 65, abt. 3.

Jackson, C. M. 1913 Postnatal growth and variability of the body and of the
various organs of the albino rat. Am. Jour. Anat., vol. 15.

Klose, H., and Vogt, H. 1910 Klinik und Biologie der Thymusdriise mit
besonderer Beriicksichtung ihrer Beziehungen zu Knochen und Nerv-
ensystem. Beitr. klin. Chir., Bd. 69.

Kolmee, W. 1912 Beziehungen von Nebennieren und Geschlechtsfunktion.
Archiv fur die ges. Physiol., Bd. 144.

Kon, J. 1909 Hypophysenstudien. 2. Uber das Verhalten der Hypophyse
nach Kastration. Ziegler’s Beitrage .zur path. Anat. und zur allg.
Path., Bd. 64.

Livingston, A. E. 1914 Effect of castration on the weight of the pituitary in
rabbits. Proc. Soc. Exper. Biol, and Med., vol. 11, no. 2.

Marrassini, A. 1910 Sur les modifications que la castration peut determiner
dans les organes glandulaires de quelques animaux, et specialement
sur celles que l’on recontre dans l’hypophyse. Arch. Ital. de Biol.,
tom. 53.

Marrassini, A., and Luciani, L. 1911 Effets de la castration sur l’hypophyse
et sur d’autres glandulaires. Arch. Ital. Biol., tom. 56.

Marshall, F. H. A. 1910 The physiology of reproduction. Longmans & Co.,
London.

Parhon, C., and Goldstein, M. 1905 Sur l’existence d’un antagonisme entre les
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tom. 82.

46

SHINKISHI HATAI

Paton, D. N. 1904 The relationship of the thymus to the sexual organs.
Jour. Physiol., vol. 32.

1913 The nervous and chemical regulators of metabolism. McMillan
& Co., London.

Pirsche, E. 1902 De l’influence de la castration sur le developement du sque-
lette. These de Lyon.

Poncet, 1878 Influence de la castration sur le developpement du squelette.

Assoc. Franc, pour Pavanc. d. Sc. C. r. Paris.

Schenk, F. 1910 tiber die Veranderungen der Nebennieren nach Kastration.
Beitr. z. klin. Chir., Bd. 67.

Sellheim, H. 1898 Zur Lehre von den sekundaren Geschlechtscharakteren.
Beitr. z. Geb. u. Gynak., Bd. 1.

1899 Kastration und Knochenwachstum. Ibid., Bd. 2.

1901 Kastration und sekundare Geschlechtscharaktere. Ibid., Bd. 5.
Shattock, C. G., and Seligmann, C. G. 1904 Observation upon the acquire-
ment of secondary sexual characters indicating the formation of an
internal secretion by the testicle. Proc. Roy. Soc., vol. 73, London,
Soli, U. 1907 Comment se comportent les testicules chez les animaux prives
de thymus. Arch. Ital. de Biol., tom. 47.

1909 Contribution a la connaissance de la fonction du thymus chez
le poulet et chez quelques mammiferes. Arch. Ital. de Biol., tom. 52.
1909 a Modifications du developpement des os chez les animaux
prives de thymus. Arch. Ital. de Biol., tom. 52.

Steinach, E. 1910 Geschlechtstrieb und echte sekundare Geschlechtsmerkmale
als Folge der innere sekretorischen Funktion der Keimdriisen. Zen-
tralbl. f. Physiol., Bd. 24.

1912 Willkurliche Umwandlung von Saugetiermannchen in Tiere mit
ausgepragt weiblichen Geschlechtscharakteren und weiblicher Psyche.
Archiv fur die ges. Physiol., Bd. 25.

Stilling, H. 1898 Fur Anatomie der Nebenniere. Arch. f. Mikrosk. Anat.,
Bd. 52.

Stotsenburg, J. M. 1913 The effect of spaying and semi-spaying young albino
rats (Mus norvegicus albinus) on the growth in body weight and body
length. Anat. Rec., vol. 7, no. 6.

Tandler, J. 1910 tiber den Einfluss der innersekretorischen Anteile der Ge-
schlechtdriisen auf die assuere Erscheinung des Menschen. Wiener klin.
Wochenschr. Jahrg. 23.

Tandler, J., and Grosz, S. 1907 Einfluss der Kastration auf den Organismus.
Wien. klin. Wochenschr. Jahrg 20.

1913 Die biologischen Grundlagen der sekundaren Geschlechtscharak-
tere. Julius Springer, Berlin.

Vincent, S. 1912 Internal secretion and ductless glands. Edward Arnold,
London.

Giving the method of computing the percentage deviation by the use of the formulas

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i-H

id

10

lO

CD

CD

CD

CD

i>

CD

05

88

1-

cq

t-

CD

H

CO

CD CO

CO

05

CO

05

CO

*D

CO

*D

CO

00

CO

*D

CO

CD

rH

co

co

Cl

CO

CD

CO

•D

g

b

06 b

00

b

00

b

00

b

05

b

b

b

b

b

b

b

b

b

b

b

rH

b

85

b

b

b

b

1—1

cq

Cl

1— 1

a

p

BJ

cq

*

05

cq

8

CO

00

0

00

0

co

Cl

g

co

g

CD

00

a

Cl

CO cq

05

Cl

05

cc

CD

rH

«D

05

00

CD

00

cq

CO

1—1

i-H

00

a

i— <

CO 1-H

CO

ci

CO

,-H*

ci

b

b

rH

rH

rH

ci

i-H

ci

y—4

b

Cl

b

ci

b

ci

a

0

CD

CD

CD

CD

CD

CD

CD

<£>

CD

CD

CD

CD

CD

CD

85

0

ID

8

00

t'-

05

CD

Cl

i>-

1^

ID

CD

5?

05

<D

88

05

00

00

CO

05

3

05

0 00

0

05

O

05

0

O

05

O

00

0

00

0

05

O

00

O

O

00

O

00

O

00

O

P?

«

rH

0 b
0

8

b

O

O

b

8

b

b

0

b

8

rH

8

b

8

i—l

8

rH

b

0

rH

8

b

b

0

i—t

8

b

b

0

1—1

1—1

H

rH

rH

rH

r_l

rH

rH

rH

w

H

O

fc

CD

CO

co

CO

00

O

cq

l>-

CD

a

rH

0

i-H

co

8

a

P

Cl

(M

Cl

Cl

cq

Cl

Cl

cq

Cl

cq

Cl

cq

cq

0

0

m

fl © ® q

o qT CLCL o CL

o

b -e :

CL T3 h

HU

-p

p

05

V

b b :
3 S 2

-P

p

05

C5

b

05

o3

-M • ^3

0 • D

05 DC 0)
« 2 «

'i P

05

"o3 °

0

p

b

C3

05

C5

b

^ g
«

t t Eh f . H— *

05 ® 05 p

Pi

<35

« ® g

Pi

05

P

05

05 1 05

05 &

-p>

fl

U

05

05

A . Qh A, O

0 0

PH

Oh Q, O
0^0

Ph

CL

O

PH © Ph

a n.

0 ^

0

0

Ph

Ph £L

O ^

u

p S « S3

On, 0< n,

o ^

5

51

i

TABLE 6

The weights (grams) and lengths (mm.) of the bones together with the percentage of water in them in the castrated albino rats.

CM

rfi

lo

CD

CM

CD

05

o

05

CO

00

lO

05

lo

Cl

CM

05

05

cc

o

CD

D

CO

Tt<

LO

oo

oo

05

CM

00

o

05

CM

o

LO

oo

X)

J

3

CO

b

b

CO

b

rH

83

b

b

b

CO

b

b

S

b

b

o

CO

b

1—1

T— (

§8

CO

05

LO

i—i

LO

[s.

TfH

TP

05

CM

a

£

<3

T*

LO

o

Tt<

s

CD

rfi

CO

CO

CO

t>.

T}H

LO

CO

05

CO

8

fc «<

jg

b

b

b

b

b

b

b

b

o

b

b

o

on

CD

t'-

o

LO

■r

CO

CO

CD

o

2

bfi

CO

»o

§8

8

CD

CO

5

CO

CO

LO

CO

05

CO

o

CO

M

o

b

b

b

b

b

b

o

b

b

b

b

rH

on

LO

o

CD

00

oo

CM

CM

CO

LO

LO

o

05

Cl

00

00

CM

T*

u-<

CD

TJH

00

LO

CO

LO

LO

CO

LO

CO

CO

LO

Tt<

CO

3

b

b

b

b

b

b

o

b

b

o

b

CO

b

b

CO

o

o

«

C3

CO

CO

CO

CO

CO

CO

s

w

\

LO

oo

TP

05

LO

Tt<

CD

o

CM

6*

-p

s

CD

o

-f

LO

Cl

oc

00

CO

oo

LO

CO

LO

LO

1

LO

CO

CO

LO

TtH

t>

CO

o

S

b

b

b

o

b

b

o

b

b

o

b

CO

b

b

CO

b

b

CO

CO

CO

CO

CO

CO

CM

05

o

CM

00

CO

CO

CM

r-

05

-P

05

CD

LO

CD

T}H

0

Hr

o

r— 1

1— 1

rH

i— i

i—i

i—i

’—I

1

i—i

rH

l—l

^H

< <

Hi

b

b

b

b

b

b

b

b

b

b

o

d

co fc;

P P

CM

LO

S

o

CD

LO

CO

CO

$

CO

rr

S &

5

05

CD

LO

CD

LO

CO

M

r— 1

1— 1

1

i—i

rH

L-J

1—1

T— i

rH

rH

K

s

b

o

b

d

b

b

b

b

b

b

b

o

05

CM

S

o

$

CD

CO

LO

05

OO

CD

05

LO

00

CD

05

CD

£

CM

CM

CD

CM

rH

o

CM

LO

CM

o

CM

i-H

1—1

«

o

b

&

b

b

LO

CM

b

o

b

CM

o

o

b

CM

o

o

b

CM

b

b

LO

CM

i

05

o

a

CM

CM

55

CD

CD

05

o

w

+3

’m

a

cm

CD

CD

i—l

©

05

rH

LO

3

oo

O

05

rH

CO

CM

o

s

b

o'

S

o

o

LO

CM

b

o

CO

CM

b

b

b

CM

o

b

b

CM

o

o

LO

CM

!

H 1

Si

3

W

iH

O

rH

CM

•CfH

CO

gi

£

$

05

rH

CO

b

LO

b

CM

00

2 I

£

o

CM

o

CM

05

05

n 1

J

cm

cm

CM

CM

CM

CM

CM

CM

CM

1-1

A -EL

bfi bfi

rJ=3 H
bfi bfi

q >3

©

£ _
rr! ■+*

1 “

Sh Q5

Q H

•+55

■+5>

^ :

H 1

bfi •

bfi tW) .

*© •

*qj *© :

^ ^ b

bfi

£

©

i-3

©

a,

O

O

52

TABLE 6 — Continued

00

o

3

CO

tP

CO

b-

07

83

»o

©

03

$

to

CO

00

C3

o

03

03

07

o

CO

03

o

CO

07

CO

CO

07

00

07

CO

07

CO

07

1—1

8

o

o

07

00

03

00

00

00

o

CO

07

o

o

CO

Tf1

Tp

CO

to

CO

Ph

CO

©

o

d

d

d

d

d

d

07

r— |

00

o

CO

tO

>o

o

03

07

00

o

CO

TP

-p

07

tO

CO

^p

CO

d

d

o

o

o

d

o

d

tP

07

tp

o

to

"P

o

03

CO

CO

to

00

tO

1—1

to

CO

CO

CO

tP

o

to

CO

CO

d

o

o

d

07

d

d

to

o

d

07

CO

CO

CO

CO

CO

00

07

CO

00

oo

CO

CO

tp

tO

tP

co

to

to

1

to

CO

CO

CO

tP

03

to

CO

CO

d

d

o

d

07

o

o

tP

o

d

07

CO

CO

CO

CO

03

to

r-H

tP

o

"P

o

t>

to

CO

00

CO

tO

CO

07

i-i 1

]

1

1

1

o

d

d

d

d

o

d

d

t<-

, — i

i-H

03

CO

o

CO

CO

o

00

lO

07

00

CO

to

CO

07

1

1— 1

d

d

d

o

d

d

d

d

o

00

^p

CO

CO

0

CO

tO

CO

8

03

TP

07

t-

1-H

8

07

t-H

CO

o

d

35

o

o

to

07

d

d

07

o

d

to

07

tO

03

50

o

to

00

07

TP

to

-p

03

8

CO

07

oo

07

1—1

07

07

T“H

CO

d

d

00

07

d

d

d

d

!>■

07

o

d

to

07

tp

to

00

07

CO

CO

07

07

to

o

CO

tP

CO

07

o

07

8

CO

07

07

07

8

O

07

-£h -3
_bfi tbC
"S 33
* *

cq 03

S £
Q

-1-3

-M -t-=

-E -5

rC rH

bD bC

bJD bfl

*o ‘S

*03 ’S

fe '

*5> *03

> te-

T3

.2

iP yj

Q

r- fl

' 03

P* Q

^3 T3

cq 03

2 *C

P

ci

i-,

03

a,

O

03

s?

JH

03

>

<

03

Qt

O

53

TABLE 7

Giving the weight (grams) and length (mm.) data for the spayed albino rats compared with those for the controls. After spaying at

19-30 days.

savo aov

CO

CM

CO

CM

CO

CO

3 3

CO

CD

<M

CO

<M

CO

8

oo

to

g

rH

rH

r-H

rH

t-H

CM

CM

1— 1

•H3dO aaxav
SAVa 'ON

©

107

125

to

CO

g

I

133;

oo

CO

<N

CO

g

co

03

CO

b-

o

oo

CO

1— H

1-H

CO

o

n

CO

CM

CO

o

f-H

co

t>

-f

§

to

1 -

o

00

r>-

00

CO

h

CQ

CO

CO

I""*

o

’

03

CM

CO

<M

o

o

CO

CO

co

co

fc M
w a

a

m

d

<M

d

,_i

1

d

d

W

1

o

d

o

1

d

d

o

1

I-

1

t-

1

t-

t-

1

t-

t>

1

« $
w p

fc

s

l>

oo

co

Tp

o

to

§

03

Tt<

CO

O

03

CO

2

o

o

00

l'-

§

CO

CO

CM

CO

o

2

o

o

CO

o

’

CO

03

CO

t-

'T1

1>

o

PQ

d

03

o

oo

00

o

1

03

03

o

1

OO

00

u

1

00

00

w

1

oo

00

d

00

00

o

tH.

1

l>-

1

1

1

CO

to

00

TtH

o

00

CO

CO

to

C3

3

o

»o

03

i-

o

00

<M

<M

-t4

CO

03

to

TjC

o

cc

Tt<

to

r-

to

CO

to

to

<M

to

to

to

to

to

to

to

0 03
« 5° S

ft

m

O

o

d

d

o

o

d

d

d

d

d

d

CO

d

d

7

o

o

d

CM

00

03

03

co

03

3

CO

03

to

CO

O

§

03

tJH

i>

co

to

CO

CO

00

to

CM

CO

co

CJ pH

CO

00

CO

t-

-ci’

CO

i-

i'

00

00

(M

oo

d

H

«

1-1

1-1

rH

1-1

d

r“l

rH

rH

CO

1-1

d

7-1

i— t

I

*“ 1

03

to

CO

rH

o

o

oo

'g

§

g

o

CM

oo

g

o

oo

o

o

8

to

to

§

8

SISAHdOdAH

o

©

CO

o

©

o

©

00

o

CO

o

o

O

3

CO

o

o

03

6

o

d

o

d

r-H

o

o

rH

d

o

1-H

d

o

d

o

d

o

o

00

rH

<M

oo

<M

o

g

o

03

<M

03

CM

co

CM

CM

s

<o

03

o

TfH

co

co

00

rt<

O)

CO

SaiVtAHi

CO

CO

8

CO

CM

00

03

CO

CM

<M

CO

o

CO

to

§

to

i— l

co

l-H

CO

CM

CO

d

d

§

o

o

03

d

d

to

o

o

o

d

d

o

00

o

o

00

CO

i>-

CO

CO

to

o

03

to

r-H

to

<M

03

03

d

CO

03

CO

CO

00

03

CO

03

cc

savNaavadfls

o

3

to

©

o

CM

to

o

-+1

o

rtn

3

O

3

o

<M

to

o

rf

O

03

3 3

to

o

o

3

1

o

d

d

7

d

o

d

CM

1

d

d

to

1

d

o

1

d

d

d

CM

1

o

o

00

7

03

<M

£•

t-

CO

r-

Ol

t-

o

to

o

8

to

CO

CO

03

8

00

CO

00

to

-r

3 3

CO

CO

CO

<M

3

>o

i

CO

HJ

-t

aiOHAHI

00

©

o

i—i

o

o

o

o

o

o

o

CO

o

o

o

CO

o

O

o

7

o

d

d

o

d

1

d

o

O

o

o

oo

<M

1

o

o

d

o

c^

po

OO

CM

r“H

“CO

“to"

“co"

“co

“o

i—i

“CO

“oo“

to

CM

03

00

rH

co

to

CO

AHOiaAV

Aaoa

to

d

CO

CO

d

d

03

d

CO

d

d

d

to

to

d

to

to

OO

CM

03

to

CO

03

00

1— t

1—1

<M

d

<M

<M

CM

o

co

CM

co

_

l

CO

<M

CO

03

00

oo

00

CO

C3

co

!>.

CO

b-

CO

t-

00

CO

ULLtjjvia. i iiTOi

d

1—1

CM

d

1

to

H

o

1—1

CO

r— 1

o

CM

o

03

OO

CO

CO

1— H

t-H

TT

03

HxoNaa

Aaoa

00

o

03

03

O

03

03

o

03

03

o

o

o

o

_8

o

03

03

o

r— 1

i—l

1—1

rH

i— 1

_l-H

<M

d

CM

“O

OO

sasvo 'on

to

TF

co

to

to

to

to

CO

(M

. 'P

3 d

Ph c3
Hf Ph

P ©
P.

P

0

O

1

ti

<13

a

O

. "d

— < 03

O

OOPhOOPhOOPmOOPmOO^

e 3 * *

HH>

0

o

T3

o

■+3

o

—H . .

H-H o

3

T3

©

HJ

o

— H

o3

o

pH

C3 S

o3

o

H-3

—

o

H-3

pH O

H-3

Ph

(h

0

c

pH

a

« Ph

©

o

o

Oh

o

o

&i qj

o

Pi

X

54

Giving the weight {grams) and length {mm.) data for the spayed albino rats compared with those for the controls. After spaying at

97-119 days.

SAVQ 3DV

oo oo i> u- oo oo

| 05 05 1— 1 1—1 O O

r-l i-i CM CN <M O'*

•H3dO HaijTV
SAVa ‘ON

H OO O

O 05 o

PER CENT
WATER

Sp. Cd.

71.170

71.803

0.63

71.681

71.807

0.13

71.426

71.805

0.38

Brain

78.472

78.433

-0.04

78.635

78.525

-0.11

78.554

78.479

-0.08

CENTRAL
NERVOUS SYS-
TEM

Sp. Cd.

0.509

0.520

2.0

0.542

0.551

0.90

0.526

0.536

1.5

Brain

1.699

1.728

1.6

1.820

1.792

-1.6

1.760

1.760

0

SlSAHdOdAH

0.0107

0.0108

0.88

0.0132

0.0156

14.6

0.0120

0.0132

7.8

SX1WAHI

0.1385

0.1728

20.7

0.1365

0.2235

58.4

0.1375

0.1982

39.6

STVN3HVa<mS

0.0523

0.0394

-28.2

0.0519

0.0407

-21.9

0.0521

0.0401

-25.0

dlOHAHI

0.0467

0.0267

-66.9

0.0649

0.0536

-34.4

0.0558

0.0402

-50.6

XHDiaAV Aaoa

163.9

181.1

10.1

192.1

201.0

2.7

178.0

191.1
6.4

HiONaa aivx

O to

h ffl M T)( lo O 00 (O H

JO JO | N N ® O |,

HXONaa Aaoa

00 00 03 O -rfi

00 00 © 03 O © C5 C3 O

1 1 r-H CCJ l— 1 1— 1

sasvo "on

Tji 00 to no 03 00

Control

Operated

Percent: Oper. — Cont

Control

Operated

Per cent: Oper. — Cont

Control

Operated

Percent: Oper. — Cont

[

an oho

XII

XIII

XII-

XIII

55

Giving the weight (gms .) and length (mm.) data for the spayed albino rats compared with those for the controls. After spaying at

172-195 days

9Ava aov |

i-Hl-H i-l C<J<N rH r-<

' H H C<J<N COCO N (M

<M<N (M(N (M(M

•aaao aaxav |
Siva ao ’on

CO O 1-H

O* CO CO ^

PER CENT

WATER

Sp. Cd.

71.660

71.074

-0.59

69.536

70.314

0.78

69.575

69.750

0.18

70.257

70.379

0.13

Brain

78.509

78.075

-0.43

77.593

77.862

0.27

77.614

77.811

0.18

77.905

77.913

0.01

CENTRAL
NERVOUS SYS-
TEM

I Sp. Cd.

0.510

0.498

1-2.3

0.533

0.516

1.8

0.570

0.599

0.92

0.538

0.538

0.16

Brain

1.765

1.708

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1.789

1.752

-0.32

1.920

1.933

-0.81

1.825

1.798

-1.5

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0.0082

0.0075

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0.0074

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31.2

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0.0123

6.7

0.0129

0.0149

10.4

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0.1206

0.1481

17.9

0.1078

0.1136

4.0

0.1289

0.2120

60.8

0.1191

0.1579

27.5

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0.0383

0.0341

-9.8

0.0398

0.0359

0.52

0.0391

0.0390

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0.0391

0.0363

-5.3

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0.0275

0.0263

-4.5

0.0348

0.0284

-11.5

0.0414

0.0651

57.6

0.0346

0.0399

13.9

iHDiaAV iaoa

155.1

150.5
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158.9

148.6
4.8

171.4

207.3

8.6

161.8

168.8

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Control

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Percent.: Oper.-cont

Control

Operated

Per cent: Oper.-cont

Control

Operated

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anoao

XIV

XV

XVI

XIV-

XVI

56

Percentage weight of the parts of the encephalon in albino rats after spaying at 19-80 days

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TABLE 11

The weights '(g ms.) and lengths {mm.) of the bones together with the percentage of water in them in the spayed albino rats

AGE

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TABLE 12

Giving the weight ( gms .) and length (mm.) data for the semi-castrated albino rats compared with those for the controls. After semi-cas-
tration at 17-27 days

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59

1 Weight of surviving testis.

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PER CENT

WATER

Sp.Cd.

71.077

71.254

0.18

Brain

78.241

78.342

0.10

CENTRAL

NERVOUS SYS-

TEM

Sp.Cd.

0.571

0.601

2.4

Brain

1.757

1.821

2.5

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0.0082

0.0086

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0.0997

0.1159

9.8

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0.0345

0.0364

0.87

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HXON3T xaoa

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sasvo *on

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Control

Operated

Percent: Oper.-cont. . .

anoao

VI

• S3

£

60

Percentage weight of the parts of the encephalon in albino rats after semi-castration at 17-27 days.

t

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Percent 62.8 19.8 14.7

TABLE 15

Giving the weight ( gms .) and length {mm.) data for the operated rats compared with those for the controls. After ligation of spermatic

SAVd aov

§ g s s

•aaao aaxav

SAVd *ON

98

94

PER CENT

WATER

Sp. Cd.

Brain

CENTRAL

NERVOUS SYS-

TEM

Sp. Cd.

0.541

0.538

2.6

0.537

0.531

0.38

Brain

1.839

1.842

1.3

1.858

1.848

-0.05

SISAHdOdAH

0.0073

0.0073

6.2

0.0070

0.0089

32.5

SQPIAHX

0.2508

0.1970

-20.2

0.1509

0.2649

41.8

savNaavaaas

0.0378

0.0336

-6.2

0.0314

0.0401

30.6

aioaAHi

0.0464

0.0364

-21.9

0.0196

0.0240

17.4

saxsax

2.438

1.314

-31.6

2.145

0.289

-93.2

XHDI3AV AdOH

224.4
207.2

0.59

197.0

188.4
10.5

HXONaa aivx

176

170

-0.57

163

166

3.1

HiONaa Aaoa

© O O 05 05 o

CsJ (M 1-H 1— (

sasvo -on

CO CO CO CO

Control

Operated

Per cent: Oper.-cont. . .

Control

Operated

Per cent: Oper.-cont.. .

aaoao

hH h- 1

h-H

62

O 5si

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li

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1-H i-i CM CM T-H T-H

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Siva 'ok

8 3 • $

r— 1 pH i-H

PER CENT

WATER

Sp. Cd.

71.263

71.997

0.73

70.909

71.489

0.58

71.086

71.743

0.66

Brain

78.380

78.557

0.18

78.271

78.528

0.26

78.326

78.543

0.22

CENTRAL
NERVOTJ8 SYS-
TEM

Sp. Cd.

0.536

0.539

-1.4

0.553

0.566

2.2

0.545

0.553

0.40

Brain

1.745

1.716

-2.3

1.796

1.827

1.7

1.771

1.772

-0.29

SISAHdOdAH

0.0094

0.0098

-0.19

0.0142

0.0150

5.6

0.0118

0.0124

2.7

SaKAHX

0.1510

0.1207

-17.0

0.1664

0.2070

24.9

0.1587

0.1639

4.0

STVNaHVHdllS

0.0437

0.0478

3.9

0.0479

0.0543

11.8

0.0458

0.0511

7.8

aiOHAHX

0.0278

0.0289

-0.18

0.0526

0.0748

67.3

0.0402

0.0519

33.6

saravAO

• _ ^ ^

eo co cm os oo to

CO H H U3 CM GO

SSeo 8 8 oo

odf 6 6 § ods

xHDiaAL iaoa

177.2

177.4
-4.6

179.8

207.3
13.4

178.5

192.4
4.4

HXONaa aivx

N O 05 H N CO tP 05 CO

CO 00 00 N ■ 00

H 1—1 CM H H CM i-Hi-H

1 0

HXONaa AdOH

1C 00 05 05 l>. 05

05050 05050 05050

sasvo 'on

^ TP CM CO CO N

Control

Operated

Per cent: Oper.-cont.. .

Control

Operated

Per cent: Oper.-cont. . .

Control

Operated

Per cent: Oper.-cont.. .

xa oao

V

VI

7VI

63

4

TABLE 17

The weights (.gins.) and lengths (mm.) of the hones together with the percentage of water in them in the semi-spayed albino rats.

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TABLE 18

Giving the weight ( gms .) and length (mm.) data for the operated albino rats compared with those for the controls. After isolation of

ovary and removal of the other at 27 days.

PER CENT
WATER

Sp. Cd.

Brain

CENTRAL
NERVOUS SYS-
TEM

Sp. Cd.

Brain

| <M CM

Siva aov © ©

1 (M <M

© ©
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CM <M

CO ©
© ©
<M <M

■aado aaxav
giva -on

SISAHdOdAH

STVNaavHdns

XHOiaAL xaoa

HioNaa aivx

HxoNaa Aaoa

© © CO
© ©

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© © d

no ©
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T-| ©

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CO b-

r-H ©

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l—l 1— I ©
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CO b-

© ©

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© © t-
© © ©

CO ©
00 00

© 00

(M 00
© b-

8%

CM ©
TH fH
© TJH
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© © CO

A

d

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a

0

0

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0

1

0

1

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(h

03

03

03

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SAVO ‘ON

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gg

Sp. Cd.

71.447

71.338

-O.ll!

1

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&

Brain

CO ©

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^ © ©

00 00 ©

N N

CENTRAL

NERVOUS SYS-

TEM

Sp. Cd.

0.508

0.541

3.7

Brain

1.661

1.707

-1.9

SISAHdOdAH

0.0122

0.0123

-3.9

SniVAHi

0.1627

0.1755

7.7

STYNaavadns

0.0447

0.0443

-5.1

J

dlOHAHi

0.0569

0.0526

-21.5

saiavAo

0.0483

0.0555

14.0

XHDiaAi. Aaoa

165.2

175.4

0.66

HiONaa aivi

166

168

-0.58

HxoNaa Aaoa

rH Tji
© © ©

sasvo *on

oo ©

Control

Operated

Per cent: Oper.-cont

dnoao

HH

65

THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 18, NO. 1

TABLE 20

Giving the percentage deviations of the various characters in the operated 'albino rats from the values found in the controls.

f

8Ava aov

i> r^ co oc

io os r^

1— 1 i-H CM 1—

i <

l

o 3

CM CM

H3dO H3X3Y

SAya *ok

oo rH to co o

CO i— • to CO o ^

f-H rH H r-H

PER CENT
WATER

Sp. Cd.

0.20

0.29

0.19

-0.30

0.38

0.13

Brain

00 0

oro-

IV o-

100

TO 0

800-

&.

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H

W

2

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►

T3

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3.3

0.32

0.08

2.5

1.5

0.16

Brain

I

2.6

0.51

-0.74

1.3

0

-1.5

SISAHdOdAH

56.7

42.6

39.1

8.9

7.8

10.4

snnAHi

61.2

74.9

53.9

58.3

39.6

27.5

83VNaavndas

17.6

6.8

8.5

-18.5

— 25.0_

-5.3

aiOHAHi

-21.5

3.8

-6.7

3.3

-50.6

13.9

saNVTO xas

XHOI3.M. Aaos

6.0

3.0

5.4

7.3

6.4

3.5

HI0N33 3IVX

4.7

3.2

1.8

1.9

-1.5

1.2

HioNai Aaoa

o o o o

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sasvo ’ON

27 C.

26 0.

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50.

7 C.

80.

30 C.

280.

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TABLE 20 — Continued

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67

*

*

>v

3 0112 072667469

THE JOURNAL OF EXPERIMENTAL ZOOLOGY,

VOLUME 18, NUMBER 1, JANUARY, 1915

CONTENTS

Shinkishi Hatai. The growth of organs in the albino rat as affected by gonadectomy 1
John C. Phillips. Experimental studies of hybridization among ducks and pheasants.

Nine plates 69

A. Franklin Shull. Inheritance in Hydatina senta. II. Characters of the females
and their parthenogenetic eggs 145

THE WAVERLY PRESS

BALTIMORE, U. S. A.