PLATE I. 



Fig. 1. — Section of egg of 5 hours, 2-oell stage, only a portion of cyto- 

 plasmic meshwork shown. X 142. 



Fig. 2. — Segment of section of egg, 5i/i hours, early 4-cell stage, meshwork 

 of cytoplasm not shown. X 142. 



Fig. 3. — Composite drawing from sections of egg of 7Mj hours, S-cell 

 stage, yolk not shown. X 142. 



Fig. 4. — Segment of one section of the preceding egg. X 142. 



Fig. 5. — Composite drawing from section of egg of ca. 10% hours, 16-cell 

 stage, yolk not shown, peripheral layer only of cytoplasm reproduced. 

 X 142. 



Fjg. 0. — Segment of one section of preceding egg. X 142. 



Fig. 7. — Composite drawing from section of egg of 11 hours, about 32-cell 

 stage, yolk not shown, peripheral layeft- only of cytoplasm reproduced. 

 X 142. 



Fig. 8. — Surface view of one hemisphere of an egg of 12 hours, stage of 

 (JO-70 cells ; few of the cells have reached the superficial layer of cytoplasm. 

 X 142. 



Fig. 9. — Segment of a section of an egg of the stage of Fig. 10. X 142. 



Fig. 10. — Surface view of one hemisphere of an egg of 11% hours, stage 

 of ca. 130-140 cells in superficial position, x 142. 



Fig. 11. — Similar view of an egg of 14 hours, stage of ca. 300 cells. X 142. 



