PLATE 5 



EXPLANATION OF FIGURES 



Drawings from sections of Arbacia eggs treated with narcotic, made with the 

 aid of a camera lucida. Magnification approximately X 2100. 



28 Egg showing nuclear spindle with absence of asters. 



29 Egg in which the pronuclei did not fuse before the nucleus was dissolved. 



30 Egg showing the division of the chromosome. 



31 Egg showing the formation of chromosome vesicles. 



32 and 33 Eggs showing cytoplasmic cleavage in narcotized eggs. 



496 



