PHYSIOLOGICAL PROPERTIES OF GONADS 167 



it possible for the completion of the process of ovulation, though 

 this seems scarcely probable. Abnormal pressure may have an 

 effect in abolishing ovulation, for obviously in its strange environ- 

 ment the graft, very often surrounded by muscle tissue, would 

 be subjected to a greater pressure than it would in its normal 

 peritoneal surroundings. It seems more probable, however, 

 that the proper physiological correlation of unknown factors 

 leading up to and initiating ovulation in the normal female 

 is not present in the male animal in which the graft is located. 

 We meet, likewise, a similar condition in young females preceding 

 the onset of sexual maturity. 



In a female rat thirty-six days after birth the ovary contains 

 many large follicles that, in the adult female, we would class as 

 mature follicles, but the rat does not become sexually mature 

 until seventy to ninety days after birth. Previous to this time, 

 the follicles do not undergo ovulation, judging from the tre- 

 mendous number of atretic follicles (fig. 12), but the follicles 

 degenerate as do those described in the grafts. In one case as 

 in the other we can assume an absence of physiological corre- 

 lation necessary for the phenomenon of ovulation, but whether 

 the seat of such influences may be within the ovary itself or in 

 some other endocrine organ is problematical. Long and Quisno 

 ('16) maintain that female rats isolated from males will ovulate 

 about every ten days, but in the grafts ovulation has evidently 

 been almost, if not entirely, suppressed; the ovum, instead, is 

 thrown out into the follicular cavity upon dissolution of the discus 

 proligerus, and there undergoes fragmentation and disappears 

 while the stratum granulosum is converted into a mass of large 

 cells containing lipoid material, that are present between the 

 developing follicles. 



One point however is perfectly apparent, the presence of a 

 normal testicle does not prevent the persistence or growth or devel- 

 opment of an ovary grafted into a male rat if this graft is made 

 early in the life of the animal. This fact established, how are we 

 to harmonize it with the facts made known by Lillie in the case 

 of the free-martin? If the blood of a male and female pair of 

 cattle twins intermix during intra-uterine development, the 



