PLATE 4 



EXPLANATION OP FIGURES 



19 to 21 (1037) Centrifuged 10 minutes in the prophase of the second mat- 

 uration division; fixed at once. The spindle was not firmly attached to the sur- 

 face layer and was carried with the cytoplasm to the centripetal pole. 



22 (1088) Centrifuged 100 tvu-ns of hand machine in about 1 minute; fixed 

 1 hour later. The second maturation spindle in the anaphase remains anchored 

 to the cell membrane at the animal pole, but is stretched in length by the centri- 

 fuging. The sperm nucleus lines near the animal pole. 



23 to 27 (1038) Centrifuged 10 minutes; fixed 3 hours later. The cytoplasm has 

 been displaced from the animal pole; the second maturation spindle remains at- 

 tached to the surface at that pole, but is greatly stretched in length. In figures 23 

 to 25 the cell constriction shows a giant polar body in the process of forming; 

 only the cell containing the d^ N will develop, in figure 23 the portion nearest the 

 animal pole, in figure 24 that nearest the vegetal pole; in figures 26 and 27 a giant 

 second polar body has been cut off. All nuclei and centrospheres within the 

 yolk are much smaller than those within the cytoplasm. 



380 



