My own experiments in castrating cocks were as follows: On August 20,
1910, I operated on a White Leghorn cock about five months old. One testis
was removed, with a small part of the end broken off, but the other, after
it was detached, was lost among the intestines. On the same day I operated
on another about thirteen weeks old, a speckled mongrel. In this case both
testes were extracted but one was slightly broken at one end, although I
was not sure that any of it was left in the body. An entire White Leghorn
of the same age as the first was kept as a control. On August 27 the two
castrated birds had recovered and were active. Their combs had diminished
in size and lost colour considerably, that of the White Leghorn was
scarcely more than half as large as that of the control. Such a rapid
diminution can scarcely he due to absorption of tissue, but shows that the
size of the normal cock's comb is largely due to distension with blood,
which ceases when the sexual organs are removed. In the following January,
the second cock, supposed to be completely castrated, was seen to make a
sexual gesture like a cock, though not a complete action like an entire
animal: this showed that the sexual instinct was not completely
suppressed. In February this same bird was seen to attempt to tread a hen,
while the white one, supposed to be less perfectly emasculated, had never
shown such male instinct.

The White Leghorn cock was killed and dissected on May 13, 1911, nine
months after castration. I found an oval body of dark, dull brown colour
loose among the intestines: this was evidently the left testis which was
separated from its natural attachment and lost in the abdomen at the time
of the operation. I examined the natural sites of the testes: on the right
side there was a small testis of considerable size, about half an inch in
diameter. When a portion of this was teased up and examined under the
microscope moving spermatozoa were seen, but they were not in swarms as in