INTERNAL SECRETION OF OVARY 253 



In the rabbit there is generally no spontaneous periodical 

 ovulation such as is observed in various other mammals 

 (according to Bouin and Ancel in the dog, horse, pig and 

 cow, in monkeys, and in man). But ovulation takes place 

 in the rabbit after coition or sexual excitement. Now, Bouin 

 and Ancel caused an artificial rupture of Graafian follicles 

 in virgin rabbits by puncturing the ripe follicles. They 

 also arranged for coition with males in which several months 

 previously the vasa deferentia had been ligatured; in these 

 experiments ovulation took place without pregnancy following. 

 Ancel and Bouin stated that in these animals a growth of the 

 uterus and the mammary glands occurred such as is normally 

 observable at the beginning of pregnancy {Fig. 113). The mam- 

 mary gland remained in this state of hypertrophy for about two 

 weeks; the climax of the uterine development was attained in 

 about ten days. Afterwards both organs began to decrease, 

 and in about 25 days passed back to their original state. There 

 is for a certain time a state of pseudo-pregnancy , to use an 

 expression of Hammond and Marshall. The examination of 

 the ovaries showed that after the artificial rupture of two or 

 three ripe follicles, these cease to develop, but other ripe follicles 

 of the same or the second ovary transform themselves into 

 corpora lutea. If all ripe follicles are punctured or destroyed 

 by cauterization, there is no formation of corpora lutea. In the 

 latter case no changes occur in the uterus or in the mammary 

 gland. There is a formation of corpora lutea also after sterile 

 coition with a ligatured male. If the corpora lutea formed are 

 destroyed, the characteristic changes undergo rapid reversal. 

 Niskoubina, a pupil of Bouin, showed that these experimentally 

 produced corpora lutea resemble, in their appearance and in 

 their duration, normal corpora lutea as present in the first half 

 of pregnancy. As Bouin and Ancel point out, there is also a 

 striking time relation between the development of the experi- 

 mentally produced corpus luteum and the changes which the 

 uterus and the mammary gland undergo ; the regression of the 

 corpus luteum begins about two weeks after puncture or sterile 

 coition, i.e., at the same time as regression of the uterus and the 

 mammary gland sets in. From all these experiments Bouin 

 and Ancel concluded that the characteristic changes which 

 take place in the uterus and in the mammary gland in the 

 beginning of pregnancy are caused by the corpus luteum. The 



