254 Chas. W. and G. T. Hargitt. 



EXPLANATION OF FIGURES. 



Drawings of figures 1-37 have been made with the aid of the Abb6 camera 

 lucida. The magnification indicated in each case is the original magnification; 

 the figures have been reduced to f the original size. 



Figs. 1-10. Cyanea arctica, drawings of entire eggs. X 360. 



Fig. 1. Two-cell stage, showing polar bodies. Cells slightly unequal in size. 



Fig. 2. Two-cell stage, cells unequal. 



Fig. 3. Two-cell stage, cells equal. 



Fig. 4. Two-cell stage, with polar bodies; the nuclei have divided the second 

 time and the ensuing division would have been equatorial. 



Fig. 5. Three-cell stage. 



Fig. 6. Four-cell stage, polar view. 



Fig. 7. Eight-cell stage, showing cleavage cavity. 



Fig. 8. Sixteen-cell stage, all cells outlined. 



Fig. 9. Twenty-four-cell stage. 



Fig. 10. Blastula near the end of cleavage, at least 200 cells present. 



Figs. 11-19. Cyanea arctica, from sections. X 715. 



Fig. 11. Two-cell stage, showing polar bodies; the spindle shows that the sec- 

 ond division would have been meridional. 



Fig. 12. Two-cell stage with 'resting' nucleus multi-vesicular. The beginning 

 of the cleavage cavity is shown. 



Fig. 13. Four-cell stage. Three of the cells only are shown and multi-vesicular 

 'resting' nuclei. Polar bodies present, the second division has been equatorial. 



Fig. 14. Eight-cell stage, with cleavage cavity and multi-vesicular nuclei. 



Fig. 15. A blastula of 24 cells. 



Fig. 16. An older blastula of about 300-400 cells. 



Figs. 17-18. Longitudinal sections of young gastrulse. 



