26o INTERNAL SECRETIONS 



raised to some details, it must be acknowledged that the 

 classification of Bouin and Ancel marked an extremely import- 

 ant step in the development of the theory of the hormonic action 

 of the ovary, as this classification implies that there is no 

 essential functional difference between the foUicles undergoing 

 atresia or the interstitial tissue on the one hand, and the 

 periodic corpus luteum on the other. Both furnish endocrine 

 cells, and they can functionally replace one another. 



The objections which may be made against the assumption 

 of Bouin and Ancel that the corpus luteum graviditatis is 

 functionally wholly different from the interstitial tissue or 

 from the periodic corpus luteum, are of more importance. We 

 have already discussed the functional relationship between the 

 interstitial tissue and the corpus luteum graviditatis; the 

 experiments of Steinach and Holzknecht provide definite proof 

 of this. But the physiological relationship between the corpus 

 luteum menstruationis and the corpus luteum graviditatis can 

 also be proved. Hitschmann and Adler (1913) have shown that 

 about ten days before menstruation the uterus undergoes 

 changes characteristic of the beginning of pregnancy. The 

 mucosa may resemble a decidua of early pregnancy to such a 

 degree that there is no microscopical difference between the 

 two; the cells are polygonal, the glands are long and curved, 

 the blood vessels are enlarged. Evidently the essential part 

 of the process is not the menstrual bleeding, but the early 

 transformation of the mucosa into a decidua. The menstrual 

 bleeding is only a sign of the beginning of involution, which 

 takes place if there is no fertilization. Now we know from the 

 observations of Fraenkel on the ovaries of women in abdominal 

 operations undertaken for other reasons, that the new corpus 

 luteum is already present about ten days before menstrual 

 bleeding occurs, just at the time when, according toHitschman 

 and Adler, the premenstrual changes set in. There is also a 

 swelling of the breasts, occasionally followed by secretion. 

 Similar observations concerning the corpus luteum and the 

 premenstrual uterine changes have been made also by other 

 workers such as Robert Meyer (1913) and Carl Ruge II (1913). 

 These time relations between the corpus luteum menstruationis 

 and the cyclic changes in the uterus and in the breasts, which 

 are characteristic of the beginning of pregnancy, are a sufficient 

 proof that a functional relationship exists between the corpus 



