INTERNAL SECRETION OF OVARY 267 



unacceptable. The dynamics of the corpus luteum and of the 

 uterine mucosa must be taken into account, if one is to under- 

 stand the manifold clinical cases of amenorrhoea. These 

 dynamics will also explain why under certain conditions a 

 premature disappearance or destruction of the corpus luteum 

 can accelerate menstrual bleeding. It is clear that a premature 

 menstrual bleeding may occur if the corpus luteum disappears 

 at a time when the premenstrual changes have already attained 

 a certain degree. And there will be no bleeding at all when 

 the destruction of a fresh corpus luteum is brought about very 

 early, when the developmental uterine changes have not yet 

 taken place, as in the clinical cases of Fraenkel. (See p. 251.) 



7. The Phases of Puberty in the Female. 



Usually a marked distinction is drawn between the changes 

 which take place in the genital organs and the mammary glands 

 at the time of sexual maturation, and those which take place 

 in these organs in pregnancy. There is evidently a tacit as- 

 sumption that the attachment of the ovum and the placenta 

 and foetus produce the changes characteristic of pregnancy 

 which are indeed in many wa^^s different from those occurring 

 during sexual maturation. There can be no doubt that the 

 placenta and the foetus are responsible to a certain degree for 

 the changes of pregnancy. But, as already remarked, we have 

 as yet no certain knowledge concerning the mechanism of 

 this interaction. On the other hand it has been demonstrated 

 that changes characteristic of pregnancy can be caused experi- 

 mentally in virgin females by provoking certain changes in 

 the ovary (X-rays, transplantation). So it seems impossible 

 to separate rigorously the changes of pregnancy from those of 

 sexual maturation, and we agree with Steinach that it depends 

 upon the endocrine apparatus of the ovary whether the 

 genital organs and the mammary glands shall attain the stage 

 characteristic of the normal sexually mature virgin female, or 

 whether these organs shall attain, after fertihzation, the stage 

 of development characteristic of pregnancy. It can scarcely 

 be denied that other parts of the organism also and other 

 ductless glands besides the ovary contribute to the changes 

 of pregnancy. But nevertheless it seems more than probable 

 that this interaction of the other internally secreting glands 



