INTERNAL SECRETION OF OVARY 259 



is performed by the interstitial tissue in the restricted sense 

 of the term. The authors pointed out that the interstitial 

 tissue and the periodic corpus luteum are both derived from 

 follicles, and both consist of similar cells, and that in species 

 with spontaneous ovulation the first periodic corpus luteum 

 appears at the time of puberty, at which time in species without 

 spontaneous ovulation the interstitial tissue just attains full 

 development. Bouin and Ancel hold the opinion that the 

 interstitial tissue and the periodic corpus luteum are responsible 

 for the development of the female sexual characters in the same 

 kind of way as is effected in the male by the interstitial cells of 

 the testicle ; but they think that the corpus luteum graviditatis 

 is functionally different from the interstitial tissue or the 

 periodic corpora lutea. 



Objections may be made to some of the details in the 

 classification of Bouin and Ancel. A spontaneous ovulation 

 may occur in the rabbit and in the guinea pig. This was 

 already known to Bouin and Ancel. I have convinced myself 

 that real corpora lutea may occur also in virgin rabbits even 

 at an age of about seven months;^ but in other cases, indeed, 

 I could not detect real corpora lutea in the ovaries of virgin 

 rabbits even 12 to 20 months old. Corpora lutea in virgin 

 guinea pigs are described by Aschner (1914 b, p. 459). Corpora 

 lutea have been found several times by various observers also in 

 engrafted ovaries of guinea pigs and rats. There is also no 

 sharp distinction between the real corpus luteum and the 

 atretic follicle. It must be borne in mind further that in those 

 species where a compact interstitial tissue is absent, atretic 

 folhcles are present in the ovary, and that there is no essential 

 difference between these two formations (see also p. 227). This 

 is why I proposed in the first edition of this book to alter the 

 classification of Bouin and Ancel in the following manner: first, 

 species in which periodic corpora lutea are not always formed 

 and there is a well developed interstitial tissue, and, secondly, 

 those with periodic corpora lutea and less developed interstitial 

 tissue. In species where the periodic corpora lutea play a 

 smaller role, the compact interstitial tissue acts as a compensa- 

 tory organ. Notwithstanding the objections which have been 



1 Dr. Hammond has drawn my attention to the possibility of this being 

 caused by the sexual intercourse between females as often observed. Then 

 the corpus luteum of the virgin rabbit is to be explained on similar Hues to 

 those in the experiments of Bouin and Ancel. 



