630 GRIFFIN. 



EXPLANATION OF PLATE XXXIL 

 ( Thalassema ynellita.) 



Fig. 19. First polar telophase, showing inner centrosomes already diverged, 

 in preparation for formation of second polar amphiaster. Sperm-head and aster 

 at $. 



Fig. 20. Second polar spindle radially situated. Prophase of mitosis of first 

 polar body. 



Fig. 21. Same, mitosis of first polar body further advanced. 



Figs. 22-24. Stages in mitosis of first polar body. 



Fig. 25. Beginning of second polar anaphase; spindle in polar body situated 

 vertically. 



Fig. 26- Second polar telophase ; extruding polar body, " cell-plate," double 

 inner centrosome. Sperm-nucleus and amphiaster at $. 



Fig. 27. Sperm-head with amphiaster. 



Fig. 28. Anaphase of mitosis of first polar body. Egg-chromosomes formed 

 into vesicles. 



Fig. 29. Polar bodies ; abortive attempt at division of the first has resulted in 

 formation of two masses of chromatin, one at each pole. 



Figs. 30 and 31. Telophase of mitosis of first polar body. 



Fig. 32. Germ-nuclei approaching ; persistence of sperm-centrosomes and 

 asters, disappearance of the egg-center. 



Fig. 33. Copulation of germ-nuclei, persistence of centrosomes. 



