INTERNAL SECRETION OF OVARY 275 



Pearl there cannot be the sHghtest doubt as to this. The 

 interstitial cells of the ovary are identical, as to their structure, 

 with the interstitial cells of the testis. Since the interstitial 

 cells, according to Boring and Pearl, are not a constant element 

 in the anatomy of the testis of the domestic fowl, the authors 

 hnd it very difficult to suppose that these cells have any causal 

 influence upon the sex characters. Thej^ consider the lutear cells 

 only to be the seat of hormone-production in the ovary. This 

 assumption is based mainly on a thorough study of several cases 

 of hermaphrodite birds which revealed certain male characters. 

 They examined the question as to how far the intermingling of 

 male and female sex characters in any individual case could be 

 explained by an abnorrfiahty in the structure of the respective 

 gonads. From this detailed examination. Boring and Pearl 

 concluded that the "amount of lutear cells or pigment is in 

 precise correlation with the degree of external somatic female- 

 ness exhibited by the individual." We shall return to this 

 paper of Boring and Pearl in the chapter on" Intersexuality." 



It may be insisted here that the conception of Boring and 

 Pearl does not agree with the statements of Goodale (19 19), and 

 especially with those of Nonidez (1920, 1922). They consider 

 the granule-containing interstitial cells of the ovary, like those 

 of the testis, to be modified lymphoid elements. But besides 

 these cells there is, according to Nonidez, in the ovary and in 

 the testis of the fowl still another type of interstitial cells 

 originating from degenerating sexual cords. These are the 

 lutear cells of Boring and Pearl. 



In * Part A' of this chapter we learned the very interesting 

 fact that ovarian fragments in the mammal undergo hyper- 

 trophy, this being caused by a relatively greater number of ova 

 entering upon follicular development, and the absolute number 

 of developed follicles after partial castration approaching 

 the total number present in two normal ovaries. Similar 

 statements were made by Pearl and Schoppe (1921), on exact 

 quantitative lines, on the fowl long before the experiments of 

 Arai and those of myself on the mammal. These authors 

 found that in the ovary which regenerated from an ovarian 

 fragment, originally of about ^ to | of a normal ovary, almost 

 the normal quantity of visible oocytes was present. As 

 there is in the fowl no new formation of oocytes, the "regene- 

 ration" of an ovarian fragment can here be explained 



