INTERNAL SECRETION OF OVARY 257 



that the spontaneous movements of the uterus, which, as he 

 showed experimentally, depend on the sexual hormones, appear 

 in the guinea pig at an age of one month, and attain their 

 maximal height at an age of about two months. Now the first 

 ovulation takes place long afterwards. Athias suggests that 

 the chromatolytic processes going on in the granulosa of the 

 follicle during atresia (Salazar, 1919), and resembling secretory 

 processes very closely, are a source of sexual hormones. Pro- 

 duction of hormones is evidently possible only when a certain 

 degree of development is attained by the follicle and the inter- 

 stitial cells ; this is shown by the following observation of Athias. 

 The ovary of the guinea pig, according to Athias, already con- 

 tains interstitial cells and normal follicles in the first month; 

 since uterine movements are absent, it seems clear that at this 

 stage follicles and interstitial cells are not capable of furnishing 

 the hormones acting on the uterus. 



Interesting experiments on the question of functional 

 relationship between the corpus luteum and the interstitial 

 tissue have been performed lately by Haberlandt (1921, 1922). 

 It has long been known that ovulation is inhibited by the 

 corpus luteum. L. Loeb (1910, 1918) showed that in the guinea 

 pig extirpation of the corpora lutea in the first week after 

 ovulation hastens the next ovulation. By extirpation of the 

 corpora lutea an ovulation can be experimentally produced 

 even in pregnancy, whereas there is normally, in the guinea pig, 

 an atresia of all but the smallest follicles. These experiments 

 show that the persistence of corpora lutea, not pregnancy itself, 

 is what prevents ovulation. Ovulation can be experimentally 

 inhibited by injection of an extract of corpus luteum, as 

 shown by the experiments of Pearl and Surface (1914) on 

 fowls, and Herrmann and Stein (1916) on rabbits and rats. 

 Now Haberlandt engrafted subcutaneously into rabbits which 

 previously had given birth to young the ovaries from pregnant 

 animals ; the normal ovaries remained untouched. One to four 

 weeks after the operation the animals were put with males. 

 Whereas normally fertilization takes place after two or three 

 coitions, the experimental animals remained sterile for one 

 and a half to three months, or after 14 to 21 coitions. Similar 

 results were obtained with guinea pigs. The histological 

 examination of the grafts revealed that no corpora lutea were 

 present, but there was a small number of atretic follicles and 



