INTERNAL SECRETION OF OVARY 243 



development, the hypertrophy of an ovarian fragment being 

 nothing else than the follicular development of a relatively 

 greater but absolutely normal number of ova (Lipschutz, 

 1922 a, b, c). My observation gives strong support to the 

 assumption that the cells derived from the follicle at different 

 stages of development form part of the endocrine apparatus 

 of the ovary whereas the oocytes themselves are not involved 

 in the endocrine function. 



Recently Haberlandt (1921, 1922) has performed experiments 

 which give further evidence of the intensified endocrine function 

 of the transplanted ovary. We shall discuss these in another 

 section of this chapter. 



We still have to deal with the fact that the endocrine function 

 of the ovary is regulated by quantitative laws very different 

 from those valid for the testicle. Whereas it seemed possible 

 to us to accept in accordance with Pezard the validity of the 

 law of "All or Nothing" for the testicle, we see that, for the 

 ovary, increase of endocrine cells causes increase of endocrine 

 function. The cUmax of the latter is attained when the corpus 

 luteum graviditatis is formed. 



5. The Condition of the Ovary in Partial Castration. 

 We saw that testicular fragments never hypertrophy in 

 the mammal, but nevertheless are sufficient for performing a 

 normal endocrine function, even when they are extremely 

 small. On the other hand, ovarian fragments hypertrophy 

 to a very considerable extent, as was demonstrated by Bond 

 and Horsley, and Carmichael and Marshall (1908), and 

 confirmed by ourselves (1922). Very small ovarian fragments 

 can attain the volume of a normal ovary. In this respect 

 there is no difference between ovarian fragments in partial 

 castration and the whole ovary after unilateral castration; 

 various authors, and lately Arai and myself, have demon- 

 strated that the remaining ovary doubles its weight. Arai 

 (1920 a, b) has shown that the number of ripening follicles 

 in the remaining ovary is twice as large as in the normal one. 

 This means that the number of ripening follicles present in 

 the body of a given species is constant at a given age. Arai 

 has counted also the total number of ova in the normal and 

 the remaining ovary, and has come to the conclusion that the 

 total number of ova in the latter is the same as in the former. 

 Evidently the hypertrophy of the ovary is to be explained 



