THE URINOGENITAL SYSTEM 393 
indifferent gonad, viz., the stroma cells and the sexual cords 
(segmental or genital cords). The stroma is formed from mesen- 
chyme situated internal to the germinal epithelium. It is a 
very narrow layer at first, and is formed, in part at least, by pro- 
liferation of the germinal epithelium itself, in the same manner 
as mesenchyme is formed elsewhere by proliferation from the 
mesoderm. The stroma of the gonad is separated from the tubules 
Fig. 226. — Cross-section through the genital primordium of Limosa xgo- 
cephala. (After Hoffmann, from Felix and Bihler.) 
The stage is similar to that of a chick embryo of 44 days. 
Germ., Germinal epithelium. Mst., Mesentery. 8. C., Sexual cords. 
V., Posterior cardinal vein. W..D., Wolffian duct. 
of the Wolffian body by the numerous blood-vessels on the me- 
dian aspect of the latter. Up to the middle of the period of 
incubation, and a little later, it is extremely sparse; it increases 
subsequently as a result of ingrowth of the blood-vessels and 
accompanying connective tissue. 
