46 CRAN1ATA. 



In the first mode the protoplasm of all the cells forming a 

 nest unites into a single mass containing the nuclei of the previously 

 independent ova (Hg. 19, nn). The nuclei in the nest increase 

 in number, probably by division, and at the same time the nest 

 itself increases in size. The nuclei while increasing in number 



o 



FIG. 19. SECTION THROUGH PART OF THE GERMINAL EPITHELIUM OF THE ov ART OF SCYLLIUM 



AT THE TIME WHEN THE PRIMITIVE GERMINAL CELLS ARE BECOMING CONVERTED 

 INTO OVA. 



nn. Nests formed of agglomerated germinal cells. The nuclei of these cells are 

 imbedded in undivided protoplasm, d.o. developing ova. o. ovum with follicle. 

 p.o. primitive germinal cell. d.v. blood-vessels. 



also undergo important changes. A segregation of their contents 

 takes place, and the granular part (nuclear substance) forms a 

 mass close to one side of the membrane of the nucleus, while the 

 remainder of the nucleus is filled with a clear fluid. The whole 

 nucleus at the same time increases somewhat in size. The granular 

 mass gradually assumes a stellate form, and finally becomes a beauti- 

 ful reticulum, of the character so well known in nuclei, (Fig. 19, do). 

 Two or three special nucleoli are present, and form the nodal points 

 of the reticulum, while its meshes are filled up with the clear 

 fluid constituents of the nucleus. Not all the nuclei undergo the 

 above changes ; but some of them stop short in their development, 

 undergo atrophy, and appear finally to be absorbed as pabulum 

 by the protoplasm of the nest. Such nuclei in a state of degenera- 

 tion are shewn in fig. 19. Thus only a few nuclei out of a 

 nest undergo a complete development. At first the protoplasm 

 of the nest is clear and transparent, but as the nuclei undergo 

 their changes the protoplasm becomes more granular, and a specially 

 large quantity of granular protoplasm is generally present around 

 the most developed nuclei, and these with their protoplasm gradually 

 become constricted off from the nest, and constitute the permanent 

 ova. (Fig. 19, do.} The relative number of ova which may develope 

 from a single nest is subject to great variation. The object of the 

 whole occurrence of the fusion of primitive ova and the subsequent 



