Rickett.—Fertilization of Sphaerocarpos. 
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PLATE IV. 
Fig. 14. Male and female nuclei in the fifth phase. Sixty-two and a half hours after flooding. 
Fig. 15. Male nucleus which has its chromatin in the form of a spireme. Seventy-one and a half 
hours after flooding. 
Fig. 16. Early example of the sixth phase. Each nucleus a group of chromosomes surrounded 
by a membrane. Cytoplasm definitely organized for the first division. Sixty hours after flooding. 
Fig. 17. Remainder of female nucleus of preceding figure. 
Fig. 18. Sixth phase. Nuclear membranes have disappeared. Sixty hours after flooding. 
Fig. 19. Sixth phase. Equatorial plate of first division. Seventy-three and three-quarter hours 
after flooding. 
Fig. 20. Seventh phase. Two-celled embryo. Sixty-eight hours after flooding. 
Fig. 2i. Chromosomes in the second division of the zygote. Polar view of equatorial plate. 
Sixty-eight hours after flooding. 
Fig. 22. Same as Fig. 21. Side view showing spindle. Sixty-four hours after flooding. 
Fig. 23. Gametophytic chromosomes in a dividing cell of the venter. Side view of equatorial 
plate. ‘ ' 
Fig. 24. Same as Fig. 23. Anaphase. 
Fig. 25. Polyspermy. Male nuclei as in fourth phase, egg beginning to degenerate. Several 
more male nuclei appear in adjacent sections. Sixty-seven and a half hours after flooding. 
