460 



CHARLES H. SWIFT 



An interesting fact, and one to which attention has not been 

 previously called, is the presence of more primordial germ-cells 

 in the germinal epithelimn of the left female gonad than in the 

 epithelium of the male gonad (fig. 5). Since, as has been pre- 

 viously stated, the germ-cells play a passive role only, this can 

 be accounted for only by the fact that the germinal epithelium 

 of the left female gonad is increasing in thickness during the 

 genesis of the cords of the first proliferation and so in this way 



coelorn 



I J no. 



aermep. 





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Fig. 6 Portion of a transverse section through embryonic ovary of a T-day 

 chick. This drawing shows the thick germinal epithelium, containing many 

 germ-cells, which is characteristic of the female gonad before appearance of the 

 cords of second proliferation. 



many of the primordial germ-cells are taken away from the sites 

 of local hyperplasia which give rise to the sexual cords. 



All these factors are of relative value only, and it is only by 

 invoking them all, that any certainty as to the sex of the in- 

 dividual may be reached. 



In the 7-day female gonad or embryonic ovary the germinal 

 epithelium is composed of several layers of cells (fig. 6). The 

 layers are not very definite and cannot be traced for any dis- 



