36 RALPH E. WAGER. 



Explanation of Plate III. 



Fig. 14. Dislal portion of an egg at about the time of its breaking through the 

 ectoderm, and previous to the process of maturation. The nucleus at this time 

 becomes less darkly staining, and irregular in outline. The pseudo-cells are typical 

 in that there are shown the variety of forms and sizes. X ^SO- 



Fig. 15. A nest of nucleolar bodies which have evidently been derived from a 

 single nucleus by the dissolution of the nuclear membrane. These stain with different 

 degrees of intensity, and in double staining, in different colors, indicating their differ- 

 ence in composition. X ^5°- 



Fig. i5. a, section through a pseudo-cell showing the thin rim of darkly staining 

 material and the nucleoli arranged within it. b, another section in which the periph- 

 eral disposition of the nucleolar masses is conspicuous, c, a pseudo-cell in which 

 the nucleoli are shown in the pole opposite the darkly staining one. In this case they 

 take a distinct plasma stain when double stained. X ^5°- 



Fig. 17. Cross-section of a pseudo-cell probably derived from a nucleus. The 

 peripheral disposition of the chromatin is apparent in this as in the other cases. X ^S^- 



Fig. 18. a pseudo-cell which shows its triple origin. Three nuclear masses are 

 apparent as also three separate areas which stain darkly. X ^S^- 



Fig. 19. A very large body found just outside of a growing egg, and in which 

 were shown four well defined nuclei and traces of a fifth. Such conditions were found 

 but once and may have been an artifact. However, the very large size of some of 

 the pseudo-cells indicates that such large masses of coalesced cells frequently occur. 



X 850. 



Fig. 20. A number of nuclei as found in some ot the cells outside of the egg. 

 There were in some a number of nucleolar bodies which were not of true chromatic 

 origin but apparently food masses within the nucleus. They were of a yellowish 

 color. These were not found in all cases, but those sections on which they were 

 found were apparently well fixed and stained. Possibly their presence depended 

 upon certain metabolic processes. X 850. 



Fig. 21. Three stages in the metamorphosis of a whole cell into a pseudo-cell. 

 In a, the outline of the nucleus is still evident and traces of the chromatin filaments 

 are also visible. The nucleoli are peripherally arranged within the nucleus. In b, 

 the nucleolar bodies have become massed together and the hemisphere of the cell in 

 which they lie is slightly more darkly staining than in the previous figure. 1 n c, the 

 transformation is complete. The nucleolar mass is visible, but its containing hemi- 

 sphere is now very darkly staining, the boundary of the stained being sometimes 

 sharply defined from the unstained portion. X 650. 



Fig. 22. One of the flattened short spiculated eggs ; drawn from a section. 



Fig. 23. A series of drawings of a segmenting egg. a, b and c, the beginning, 

 middle and ending, of the first cleavage, d, the four-celled stage. Up to this time 

 cleavage is regular, total and equal. .?, drawing showing the irregularity of the later 

 cleavages. In this case the cleavage lines were not entirely visible f, g and h, later 

 stages, showing more pronounced irregularities. 



