228 CHARLES R. STOCKARD AND GEORGE N. PAPANICOLAOU. 



facilitates the act of copulation. This abundant frothy mucous 

 accumulation is limited to the first stage, particularly to the time 

 when copulation takes place, and it never occurs in the vagina at 

 other times. The second contributory condition is the complete 

 absence of leucocytes in the mucous fluid. The leucocytes begin 

 their migration through the epithelium of the uterus and vagina at 

 the end of the second stage. . They are extremely abundant in 

 the lumen during the third stage, while from this time on they 

 are found in the uterus and vagina in smaller or larger quantities 

 up to the approach of the next first stage. Two days before the 

 first stage begins leucocytes are still plentiful, but from this time 

 first stage epithelial cells gradually become more abundant and 

 the leucocytes decrease in number until finally when the first 

 stage has actually arrived no leucocyte exists in the vaginal fluid. 

 The mucous content of the vagina during the first stage hence 

 lacks the pus-like appearance of the vaginal fluid of the "inter- 

 menstrual" time and is clear and foamy. 



The absence of leucocytes from the vaginal lumen at the time 

 of copulation is important, since, if present, they might by their 

 dissolving powers or phagocytic action exert an injurious effect 

 on the spermatozoa and thus interfere with their normal function. 

 Later a special purpose of the leucocytes seems to be to destroy 

 the excess of spermatozoa remaining in the uterus. This fre- 

 quently occurs by an interesting process of phagocytosis. A 

 leucocyte comes in contact with a spermatozoon which with its 

 tail is longer than the leucocyte. The leucocyte by stretching 

 and contracting finally takes into itself the entire spermatozoon, 

 the tail being wound in circular fashion within the cell body. 

 The leucocytes, however, apparently accomplish most destruc- 

 tion by their dissolving or disintegrating action. 



It seems that the migration of the leucocytes through the 

 walls of the uterus and vagina, though not increased in extent, is 

 accelerated by the act of copulation and the entire oestrous 

 process is shorter than in non-copulated females. About six 

 hours after copulation the third stage is in full development, 

 while under virgin conditions a comparable stage is reached only 

 after at least twelve hours from the time when copulation 

 might have occurred. It may be said that copulation tends to 



