PLATE 4 



EXPLANATION OF FIGURES 



G Uterine ovum, No. 52 (7), with pronuclei near the center. The pronuclei 

 are not in the same section in the series, but are here represented together, the 

 drawing having been made by superimposing the two sections containing the 

 pronuclei (X 790). 



7 Fertilized uterine ovum. No. 54 (4), with chromosomes of first cleavage 

 spindle. An luiusual preponderance of yolk vacuoles is to bo noticed in the 

 lower hemisphere of the egg (X 790). 



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