AXIAL SUSCEPTIBILITY GRADIENTS. 



397 



The unfertilized eggs in KCN m/ioo show death changes of 

 the character indicated in Figs. 1-3. First, one or more clear 

 droplets or masses which contain some colloids and much water 

 appear on the surface of the egg and grow larger, while the 

 granular portion decreases in size. This process may go on, the 

 clear masses often uniting, until the clear and granular portions 

 are almost equal in size, but finally the granules spread and the 



4 



5 



distinction between clear and granular areas disappears. The 

 only indication of a susceptibility gradient is the appearance 

 of the clear droplets only or earlier on one hemisphere or at one 

 pole. Within certain limits of concentration this has been 

 observed in some 7080 per cent, of the eggs, but in some eggs 

 the clear droplets appear at opposite poles or over various parts 

 of the surface at the same time. The fertilized eggs before 

 cleavage (Figs. 4-6) behave in KCN essentially like the un- 

 fertilized. 



The blastomeres of the earlier cleavages show a similar separa- 

 tion into clear and granular areas and here again the clear areas 

 or droplets usually appear first or only on one hemisphere or at 

 one pole of the egg. In eggs placed in KCN after the appearance 

 of the micromeres I believe that the apical hemisphere is in 

 general more susceptible than the basal. 



An interesting gradient in the first cleavage appears in certain 

 concentrations of cyanide. In such cases the first cleavage plane 

 at its first appearance extends as a furrow only half way or less 

 around the egg and cuts through the egg in one direction without 

 the appearance of any furrow on the opposite side (Figs. 7-10). 

 In some cases a larger or smaller portion of the cytoplasm is 

 separated from the two blastomeres at the end of this cleavage 



