1 38 MUNSON. [Vol. XV. 



system of netted fibers, but yet more abundant around the 

 periphery of the nucleus. Here some of the chromatin granules 

 become aggregated into a homogeneous mass, which is often 

 closely applied to the periphery of the nucleus, and flattened 

 on that side, but otherwise spherical. This being, no doubt, 

 the first appearance of the nucleolus, the nucleus has, at this 

 early stage, the main features of the germinal vesicle of later 

 stages. The cytoplasm is still rather limited in amount, but 

 a distinct cytoreticulum can be made out. This possesses 

 prominent cytomicrosomes that stain as readily in chromatin 

 stains, especially at the nodes, as the chromatin within the 

 nucleus. 



In the cytoplasm, close to the nucleus, the archoplasm with 

 a distinct centrosome can be seen (PL XIV, Figs. 42, 43). 



8. Relation of the egg to the ovary. — On the first appear- 

 ance of the growing oocyte, in animals from five to six inches, 

 the ovarian tubes are still round in section (PI. XIV, Figs. 

 34> 37' 38). and no diverticula have appeared. As the oocyte 

 increases in size, however, it sinks more and more below the 

 neighboring epithelial cells, as stated by Kingsley (PI. XIV, 

 Figs. 34, 38, 39). These, as has been observed, are the sister 

 cells of the same group, and for some time partly enclose the 

 growing oocyte as temporary follicle cells. 



The basement membrane becomes gradually pushed out as 

 the egg grows, until it forms an investing membrane of the 

 egg, which, remaining organically connected with the follicle 

 cells only by a narrow isthmus, appears to lie wholly outside of 

 the tube, between the germinal epithelium and the peritoneal 

 coat (PI. XIV, Fig. 40). Being still invested with the tunica 

 propria, however, it is still within the ovarian tube, and in fact 

 never leaves it (PI. XIV, Fig. 19, t.p). As the oocyte moves 

 outward the sister cells belonging to the group assume more 

 and more the appearance of epithelial cells (PI. XIV, Fig. 34). 

 New oocytes within the tube begin a similar career of growth. 

 It thus happens that in an animal seven inches long where some 

 of the tubes have acquired a considerable lumen, two or three 

 stages of these young oocytes may be observed (PI. XIV, Fig. 

 40). Only one diverticulum, in cross section, has yet been 



