34 RALPH E. WAGER. 



Explanation of Plate II. 



Fig. 9 A drawing of a part of a growing egg showing tlie nucleus in the process 

 of shortening from the elongated form. The character of the cells outside of the egg 

 itself is typical. In one of them the regressive changes are well under way, the 

 nuclear membrane having disappeared entirely, and the chromatin filaments set free 

 in the cytoplasm. One of the very large cells, probably resulting from the coalescence 

 of two cells, is likewise shown. Darkly staining lines in chromatin material indicate 

 the probable fate of the nuclear stuff. 



Within the nucleus of the egg are a large number of nucleoli and a single large 

 nucleolus. In the cytoplasm is a tangle of filaments evidently the remnants of a 

 cell whose mass has been added to that of the egg. Several metaplasmic bodies are 

 also visible. X ^5°- 



Fig. io. A portion of a growing egg and a group of cells upon its periphery. 

 The very large cell, probably derived from the fusion of two or more, is about to unite 

 with the egg mass. In its nucleus the regressive changes are well advanced. In 

 the small cell outside of this large one, the chromatin has assembled in the spireme, 

 preparatory to union with the large cell. X ^SO- 



Fig. II. a part of an egg in which occurred one of the very large pseudo-cells. 

 Three thickened and darkly staining portions of its rim are noticeable. Along its 

 edges, in two places at least, one can see the nucleoli from the cells contributing to 

 the mass. X 650. 



Fig. 12. a portion of the ectodermal layer of a fully segmented egg showing the 

 manner of outgrowth of the cells previous to the formation of the chitinous shell. 

 X650. 



Fig. 13. The beginning of the shell formation by the development of the chitinous 

 layer outside of the ectodermal processes. X 650. 



