INTERNAL SECRETION OF OVARY 255 



placenta and the foetus are evidently not necessary for the 

 occurrence of these changes. The conclusions of Bouin and 

 Ancel are in accordance with those of Fraenkel. Hammond and 

 Marshall (19 14) confirmed Ancel and Bouin's description of the 

 uterine changes occurring under luteal influence in the rabbit. 



It is not intended here to give a full account of all the con- 

 troversies concerning the question as to the endocrine function 

 of the corpus luteum. This organ is, indeed, not the only 

 factor involved in the uterine changes in pregnancy, as is 

 shown by the above-mentioned experiments of L. Loeb, in 

 which deciduomata were experimentally produced at the time 

 of "heat" by mechanical stimulation of the uterine mucosa. 

 On the other hand, Loeb showed it to be probable that the 

 longer persistence of the corpus luteum is due to the presence 

 of the maternal placenta. He stated that after degeneration 

 of the experimentally produced deciduomata ovulation again 

 occurred, i.e., the corpus luteum which hitherto inhibited 

 ovulation now ceased to do this. Possibly the embryo con- 

 tributes towards the preservation of the decidua, and the 

 decidua to the persistence of the corpus luteum, which in its 

 turn inhibits a new ovulation and assists in the further develop- 

 ment of the decidua. The observations of Biedl, Peters and 

 Hofstdtter (1921), who, like Heape, implanted fertilized ova 

 into the uteri of non-pregnant rabbits, give some experimental 

 evidence for such an assumption. These observers stated that 

 the implanted ova can undergo further development for some 

 time in the foster-mother. They state further that they some- 

 times observed changes in older corpora lutea in the ovary of 

 the uterine foster-mother, and these ma}^ be considered as of the 

 nature of a process of reactivation. The question needs more 

 detailed investigation before a complete solution can be 

 reached. 



In a preceding section of this chapter we have seen that an 

 intensified follicular atresia, as caused by X-rays or by trans- 

 plantation into the male, and as augmenting the quantity of the 

 epithelioid interstitial cells in the ovary, is followed by changes 

 in the uterus and the mammary gland such as are characteristic 

 of pregnancy; in these latter experiments the changes were 

 even more pronounced than in those of Bouin and Ancel. An 

 hypertrophy of the mammary gland and milk secretion can 

 evidently take place without real corpora lutea having been 



