240 CHARLES R. STOCK,ARD AND GEORGE N. PAPANICOLAOU. 



effects on the lengths of the ovulation periods of the removal of 

 corpora lutea or the application of its extracts could be investi- 

 gated to great advantage on guinea-pigs in which the cestrous 

 cycles are definitely known and followed through a number of 

 consecutive periods. This could readily be done by the method 

 before described. This method is also of value in locating the 

 early stage of developing eggs and in making exact matings for 

 studies on fertilization, etc. 



Attention may be called to further slight objections that might 

 be raised in considering Loeb's last paper. He studies the 

 conditions in the structure of the uterine wall removed from 

 females that had copulated shortly before, as well as, uteri from 

 uncopulated females, and states, page three: 'The sperm fluid 

 present in the lumen of the uterus exerts a pressure on the surface 

 epithelium and may thus contribute to the harmful influence of 

 the leucocytes." This idea is incorrect since it may be clearly 

 shown that the action of the leucocytes is equally as harmful in 

 the destruction of the uterine epithelium during the cestrous 

 period of virgin females. 



In a similar connection Loeb also finds, page n, that the 

 number of leucocytes in the uterine mucosa is much smaller 

 in animals that have not copulated. Again, page 16, "A few 

 leucocytes can also be seen in the uterus of animals in which 

 copulation had been prevented. ... In such cases (non-copu- 

 lated animals) also some degenerative changes occur in the 

 uterine epithelium, but they are less marked than in animals 

 which had copulated." These statements are not entirely in 

 accord with our findings since there is no such marked dis- 

 crepancy between virgin females and those that have copulated. 

 Such conclusions are probably due to the fact that the uteri ex- 

 amined were not removed from the non-copulated females at the 

 maximum moment of leucocyte migration and degeneration of the 

 uterine wall (our "third stage"). Loeb had no exact means of 

 knowing the comparable stages in copulated and non-copulated 

 females. 



The uterine mucosa of our virgin females may show leucocytes 

 to be equally as abundant at comparable stages as the uteri from 

 specimens after copulation. It must be recognized in this con- 



