PLATE XV. 



Fig. 28. — Yolk is beginning to form at the periphery of the egg. a, yolk glob- 

 ules; b, the yolk-nuclei of Foot; at c we meet with a peculiar condition of 

 the vitelline body. The structure no longer retains its spherical form, but 

 shows one side broken away and the contents scattered. The body has every 

 appearance of disintegrating. 



Fig. 29. — The vitelline body much vacuolated. There is merely a remnant of 

 the concentric layers left, and the entire structure seems to be dissolving and 

 mingling with the cytoplasm. 



Fig. 30. — Another vitelline body which shows no central vesicle. The structure 

 has a spongy appearance and no concentrically arranged border, a and 6, 

 yolk globules. 



Fig. 31. — Oocyte completely filled with yolk. The nucleus and vitelline body 

 are once more close together, connected by the scanty cytoplasm which re- 

 mains in the cell, a, yolk globules; 6, nucleus; e, vitelline body. 



Fig. 32. — Egg about ready to leave the follicle. The neck is rapidly diminishing 

 and the egg membrance is forming at c. The entire egg is at this time filled 

 with yolk, a, and the nucleus is close against the cell-wall, this being the 

 position of nuclei just before maturation in centrolecithal eggs. 



Fig. 33. — Portion of another egg preparing for maturation. There is no trace of 

 the vitelline body applied to the nucleus, as was found a little earlier in figure 

 31. The assumption is that it has been left behind, though at this stage so 

 much yolk obscures it. 



Fig. 3J:.— The assumption concerning the vitelline body of figure 33 is proven 

 true by this figure. Here is a segmenting egg. The nucleus at the 

 periphery has divided, forming the cells, a. At the center, among the yolk 

 globules, we find the vitelline body, b, unchanged. 



Fig. 35. — A follicular egg of Epeira, which represents those eggs without the 

 vitelline body formation. Numerous patches of food material cloud the 

 cytoplasm. 



Fig. 36. — Highly magnified vitelline body, showing the central vesicle, a, and 

 the rod-like structures within. 



