May 15,1925 Possibility of Sex Control by Artificial Insemination 
899 
tozoa. Also it is impossible to be cer¬ 
tain that all the spermatozoa ejacu¬ 
lated by the buck have been removed 
and therefore the female from which 
the seminal fluid has been recovered 
can not be used for an artificial in¬ 
semination with a centrifuged portion 
of that fluid. In fact, the records show 
that in this experiment the females 
from which as much fluid as possible 
was recovered were more likely to 
become pregnant than were those 
which were inseminated artificially. 
This furnished an excellent control 
for the insemination experiments, but 
it made necessary the use of a much 
larger number of females. An attempt 
was made to avoid this difficulty by 
using for recovering the semen 
females upon which the operation 
of salpingectomy had been performed. 
Since they could not become pregnant, 
they could be used very frequently 
and a small number of them would 
suffice for recovering enough seminal 
fluid to inseminate artificially a very 
large number of normal females. 
However, in practice this did not work 
out so well because these females did 
not come in heat any oftener than nor¬ 
mal females, that is at intervals of 
12 to 15 days, and a large number of 
them would have been necessary if one 
were to have been available every time 
a normal female was to be inseminated. 
Moreover, after several months the 
females upon which salpingectomy had 
been performed became very fat and 
almost entirely ceased to come in 
heat, and, since a number of the nor¬ 
mal females would accept service even 
when they were pregnant, the use of 
operated females was discontinued. 
Only three such females were used in 
this experiment, and the conclusions 
derived from their behavior are of little 
value by themselves, since individual¬ 
ity is such a large factor in determining 
behavior, but the conclusions reached 
agree very well with those reached by 
Lloyd-Jones and Hays {27) from more 
extensive observations. 
Ordinarily all the females which had 
not been bred within the preceding 10 
days were tested each morning or 
every alternate morning to find out 
whether they were in heat. When two 
or more were found in heat the same 
morning, a buck was allowed to serve 
one of them naturally as many times 
as he would in about 15 minutes, 
which was usually twice, but some¬ 
times three times or more, and more 
rarely only once. Then the female 
was removed and all the fluid that 
could be recovered from her vagina 
and uterus by two or three successive 
insertions of the catheter was obtained. 
If the amount of fluid was large enough 
to be handled easily, the female was 
returned to her hutch and was not 
tested again for 10 days, but if the 
amount was too small the catheter 
was filled with warm Ringer’s solution 
which was injected into the uterus and 
allowed to remain 2 or 3 minutes. 
Then the catheter was again thrust in 
and all the liquid possible was with¬ 
drawn. In this way more semen was 
recovered, diluted to a somewhat un¬ 
certain extent, so that it could be 
handled and centrifuged very con¬ 
veniently. 
The catheters 5 used were made 
from pieces of glass tubing with an 
outside diameter of 5 to 6 mm., with a 
slight bend near one end and a bulbar 
expansion near the other. The total 
length was 18 cm., and the part which 
could be thrust into the vagina and 
uterus of the female was about 12 to 
12.5 cm. long. The uterus of the 
rabbit does not have a very definite 
cervix or os, and the body of the uterus 
is short and small while the horns are 
relatively long. Because of this, the 
catheter was thrust not only into the 
vagina but also into the uterus and 
usually even a considerable distance 
into one of the horns of the uterus 
when withdrawing liquid. 
CHARACTER AND TREATMENT OP THE 
FLUID 
The fluid recovered consisted of a 
combination of semen and vesicular 
and prostatic secretions from the male 
and the vaginal and uterine secretions 
from the female. It was usually 
opaque and of a pale milky color; 
sometimes it was of a dense yellowish 
or milky white color, and sometimes it 
was almost transparent. If recovered 
from a female within two or three days 
after parturition it usually had a red¬ 
dish or brownish tinge and evidently 
contained some blood. Sometimes 
urine would be contained in the liquid. 
This would usually give it a rather 
transparent yellow color and the 
spermatozoa would be found to be 
nearly or quite motionless. Often 
there were very many round motionless 
cells about the structure of which very 
little could be made out. These were 
often associated with cases of known 
pus infection in the uterus of the female 
from which the fluid was drawn, but 
whether this relation was significant 
« This catheter or pipette, first devised in this form by Bachhuber, has been used and figured by 
Guyer in his “ Studies on Cytolysins” (IS, p. 208). 
