254 CHARLES R. STOCKARD AND G. N. PAPANICOLAOU 



uterus and the vagina and the existence of a separate causal 

 factor of menstruation independent of the ovary. 



Fraenkel's theory that the corpus luteum is an active factor 

 producing menstruation does not correspond with our observa- 

 tions. Neither, on the other hand, does the assertions of 

 Marshall and Runciman that ''the corpora lutea evidently exert 

 no influence on the occurrence of heat" seem to us justified. 

 Marshall and Runciman ('14), have advocated the importance 

 of the interstitial cells in considering the ovarian factor con- 

 cerned in the recurrence of the oestrous cycle as opposed to any 

 active effect of the corpora lutea. They point out the evident 

 incorrectness of the old views that the ovaries and uterus are 

 related by a nervous connection. Transplantation experiments 

 have shown the fallacy of such a notion and have demonstrated 

 the presence of an internal secretion from the transplanted 

 ovarian mass. Marshall then in arguing against the importance 

 of the corpus luteum uses Heape's ('97), observations which 

 showed that in monkeys menstruation might take place in the 

 absence of either ripe follicles or newly formed corpora lutea. 

 This observation, it seems to us, does not in any way point 

 towards the interstitial cells as being important. Nor does it 

 argue against our view that the absence of the corpora lutea 

 permits menstruation and that their presence exerts a protective 

 influence over the uterine mucosa. Heape's observation is per- 

 fectly in accord with this and it is to be expected that corpora 

 lutea should be either degenerate or absent when menstruation 

 occurs. 



Marshall and Runciman performed operation experiments on 

 lour bitches. At these operations they attempted to destroy the 

 large Graafian follicles by pricking with a knife or needle. In 

 the first fox terrier at least nine follicles were injured in this 

 manner. But one who has operated on the dog's ovaries knows 

 how difficult it would be to discover all of the ripe follicles and 

 almost impossible to get those on the dorsal surface of the ovary 

 which is often closely bound down and almost covered. Yet 

 it is not necessary in this discussion to question the destruction 

 of every ripening follicle since the photomicrographs, which the 



