96 LEO LOEB. 



apparently the corpora lutea from reaching full size. It is 

 furthermore probable that toward the end of the experiment 

 the ingrowth of connective tissue into the cavity of the atretic 

 follicles was somewhat delayed. Still the difference in the be- 

 havior of granulosa cells and connective tissue is striking. While 

 the former becomes dissolved as a result of the underfeeding, the 

 latter is still active and organizes the cavity of the follicle. The 

 uterus in all cases was thin, and its mucosa did not show any 

 sign of growth. The ova represent a further element still 

 active under these conditions. In the small-medium follicles 

 in process of atresia mitotic and amitotic divisions of the nuclei 

 take place, as well as a division of the superficial part of the egg 

 into cell-like fragments in which however usually nuclei are not 

 visible. 



III. SERIES. (See Table II.) 



Fifteen guinea pigs w T ere used in this series, five, weighing 

 between 534 and 380 grams at the beginning of the experiment, 

 had been bred in Missouri; ten younger ones, varying in weight 

 between 378 and 259 grams, were obtained from Iowa. Three 

 of these animals were well fed during the period of the experi- 

 ment and served as controls. In addition two other control 

 guinea pigs were examined at the beginning of the experiment. 

 We shall first describe ovaries and uterus of the control animals. 



i. Control Animals. 



Guinea Pig No. j. Weight Oct. 18, 474 grams. Nov. n, 

 tw T enty-four days after beginning of experiment, weight 613 

 grams. The animal was found pregnant. The ovaries were 

 normal ; they contained good follicles of all sizes, large follicles in 

 granulosa degeneration, good mature follicle as well as mature 

 follicles with ganulosa degeneration. Follicles in various stages 

 of connective tissue atresia. Good corpora lutea as well as 

 degenerated corpora lutea (yellow-fibrous bodies). The mam- 

 mary gland was typically proliferating. 



Guinea Pig No. 9. Weight Oct. 18, 286 grams; weight Nov. 

 2, 375 grams; examined Nov. 4. Ovaries: Good corpora lutea, 

 the cavity of which was filled with connective tissue, retrogressing 

 corpora lutea; good small and medium follicles, various stages 



