PLATE 6 



EXPLANATION OF FIGURES 



31 (1038) Centrifuged 10 minutes; fixed 3 hours later. Normal first polar 

 body has divided. Giant second polar body forming, as indicated by con- 

 striction opposite middle of second maturation spindle; latter connected to ani- 

 mal pole. Sperm nucleus and sphere in cytoplasmic lobe on right; adjoining 

 this the egg nucleus and sphere. 



32 to 34 (1040) Centrifuged 10 minutes; fixed 5 hours later. Figure 32. 

 Normal first polar body has divided; giant second polar body contains spherules 

 and peculiar (telophase) nucleus; first cleavage spindle (metaphase) in egg. 

 Figures 33 and 34. Telophase of first cleavage. First polar body normal; giant 

 second polar body containing cytoplasm and yolk, chromosomes have not formed 

 a resting nucleus; cc scattered chromaten near mid-l)ody of second maturation 

 spindle. 



35 to 41 (1145, 1146) Centrifuged 4 hours (2000 revolutions per minute); 

 fixed 6 hours later. All eggs are in the second cleavage stage and most of them 

 continued to develop normally. Most of the eggs figured (figs. 33, 34, 35, 41) 

 were centrifuged after the extrusion of the first polar body at the animal pole, 

 but before the formation of the second polar body. The latter is a giant polar 

 body and is usually extruded at some distance from the animal pole. In figures 

 36, 37, 38, and possibly figures 39 and 40 also, the eggs were centrifuged during 

 the formation of both polar bodies, and consequently both are displaced from the 

 animal pole. In these eggs the maturation pole was forced away from the ani- 

 mal pole, but the cytoplasm and the nuclei went back to the latter when centrif- 

 uging ceased. 



35 (1145) The smaller (first) polar body evidently marks the animal pole, 

 the second was formed some distance from the pole. 



36 (1146) Polar bodies larger than normal, but they contain no yolk. The 

 maturation spindles together with the cytoplasm were evidently forced away 

 from the animal pole, and the polar bodies formed at this centripetal pole; after- 

 wards the cytoplasm and nuclei moved back to their present position. Spindles 

 present for the second cleavage. 



384 



