GONADS AND THE PITUITARY BODY 



phy, following the administration of anterior-pituitary ex- 

 tracts, could be most readily demonstrated in drakes 5-8 

 months old. Ducks 1-4 months old were the least sensitive, 

 whereas adult ducks (at times other than the breeding sea- 

 son) were of intermediate sensitivity. 



The gonadotropic ejects of implants or extracts of the an- 

 terior pituitary in mammals. — The comparative physiology of 

 the gonadotropic hormone(s) in mammals is a treacherous 

 field in which many observations have been made. Too often 

 these observations are of doubtful value even from a qualita- 

 tive standpoint, especially when they are thought to suggest 

 the existence of different gonadotropic hormones. In the 

 cases of some mammals it is necessary to consider (i) the 

 gonadotropic effects of pituitary extracts in the animal itself 

 as well as (2) the gonadotropic effects of the animal's pitui- 

 tary in other mammals. 



Until there is agreement as to the real number of gonado- 

 tropic hormones, little can be said regarding the adequacy of 

 the various tests for a gonadotropic effect now in use. If one 

 chooses to disregard the qualitative aspects of the question, 

 one finds that the most sensitive test-object is probably the 

 ovary of the immature mouse. The production of ovulation 

 in the rabbit in oestrus is a very sensitive test for the presence 

 of a gonadotropic hormone. The testis of the immature 

 pigeon is said to respond more readily than the immature 

 rat's ovary provided that one is using material obtained 

 from the pars glandularis. Of the four test-objects mentioned, 

 the ovary of the immature rat appears to be least sensitive. 



So far as the qualitative peculiarities of the gonadotropic 

 effects are concerned, probably the most that can be said is 

 that the pars glandularis of the guinea pig, of the horse (espe- 

 cially if castrated), and possibly of the adult female rat pro- 

 duces chiefly a growth of follicles when tested in immature 

 mice and rats. 



So far as the concentration (disregarding qualitative ef- 



[T27] 



