456 



CHARLES H. SWIFT 



As regards the embryos of ages 4^ and 5 days, respectively, 

 the changes are not sufficient to warrant an extended description. 

 The gonads, in these stages, have increased only slightly in length, 

 but their volume, as shown by the cross-section, is considerably 

 greater. This increase of the area of the transverse section is due 

 solely to hyperplasia of the elements of the stroma, which are 



coeiom 





Fig. 4 Portion of a transverse section through indifferent gonad of a 5-day 

 embryo. In this embryo the germ-cells retained a quantity of vitellus. 



of mesenchymal origin. Proof of this is found in the numerous 

 mitotic figures. The germinal epithelium still is composed of 

 two or three layers of cells and the limiting basement membrane 

 is as distinct as of old (fig. 4). 



The primordial germ-cells have about the same distribution, 

 and are still quiescent, since only one or two in each embryo are 

 found in a state of division (fig. 4). 



