SEXUAL ACTIVITY OF MALE RABBITS 467 
This operation may generally be accomplished, but often folds 
of the vaginal wall are encountered and much patience is neces- 
sary; in very few cases was failure to introduce the atheter deep 
into the vagina complete. In very rare cases the catheter 
penetrates the bladder, rather than passing over the papilla, in 
which event the female in hand is spoiled for recovery of semen 
that day, because even a small amount of urine remaining in the 
vagina is highly inimical to the sperm. With the inner end 
of the catheter placed near the: os, a glass pipette is inserted 
into the outer end and the semen withdrawn by suction. The 
amount of material recovered is small; generally about one to three 
tenths ec., and consists of the secretions of the testes, epididymis, 
seminal vesicle, prostate and Cowper’s glands from the male. 
These may also be mixed with uterine cervical and vaginal se- 
eretions, also lymph, epithelial cells, and leucocytes from the 
female. 
During the earlier stages of the work, a female was simply 
bred once to a male for the recovery of semen without previously 
attempting to remove any uterine or vaginal secretions which 
might be present. As the work progressed, it was considered 
advisable to remove as much as possible of these secretions from 
the female, in the manner described above, before breeding her, 
and this step was worked into the routine of our practice. In 
the great majority of cases the amount of these secretions thus 
recovered before the breeding was negligible, but sometimes as 
much as 0.8 ec. was withdrawn. This material differs much in 
physical properties from semen. It is generally thicker, more 
viscous, yellowish in color, and does not mix freely with a saline 
fluid (Ringer’s), but gives a mixture with two phases. It is 
heavily loaded with leucocytes and other cells. Specimens of 
semen which are mixed in appreciable amounts with this ma- 
terial are easily recognized, and were discarded for study of 
numbers of sperm per cubic millimeter. 
