PLATE 9 



EXPLANATION OF FIGURES 



47 Normal first polar body at animal pole; giant second polar body a little 

 to one side of the animal pole; it contains cytoplasm and oil and was therefore 

 formed at the centripetal pole. 



48 Original animal pole probably indicated by the small first polar bod}-; 

 the large second polar body was formed some distance from this. During the 

 first, second and third cleavages the original polarity was not completely re- 

 stored but the positions of the micromeres and of their nuclei and centrospheres 

 indicate that there has been an attempt to restore the original polarity; in the 

 upper, yolk-laden micromeres, cytoplasm, nuclei and centrospheres are turned 

 away from the animal pole and toward those of the lower micromeres. There- 

 fore the micromere pole is somewhat removed from the original animal pole. 



49 to 54 The giant first and second polar bodies do not lie at the middle of the 

 plate of micromeres (ectodermal pole), though the normal first polar body m 

 figure 54 does; the ectodermal pole therefore coincides with the original animal 

 pole. All the micromeres are quite normal in number, size and position. 



390 



