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MYRA MELISSA SAMPSON. 



controls remained normal in appearance. This is well illustrated 

 in the percentages indicated in graphs I., II., and III. 3 



GRAPH II. The percentage of ova divided and cytolyzed by sperm nitrates of 

 the same species Arbacia. A == the average of ten experiments with nitrates 

 made from 5 per cent, suspensions. B = the average of ten sea-water controls. 

 = percentages in nitrates in individual experiments. 



It is evident that some ova, probably because of a slight 

 difference in physiological condition, are more rapidly affected 

 by the filtrates and dialyzates than others, thus indicating a 

 varying degree of susceptibility of the eggs to the action of the 

 preparations. 



In view of the failure of other investigators of this problem it is 

 important to emphasize the fact that I obtained consistent 

 results. At the same season of the year the eggs of different 



3 The graphs indicate the number divided and cytolyzed rather than simply the 

 ones in a state of division. Since the ova do not divide simultaneously, some have 

 divided and cytolyzed at a time when others are undergoing nuclear changes or are 

 dividiiiR. 



