390 



A. J. GOLDFARB. 



TABLE IV. 



SHOWS CHANGE IN CLEAVAGE WHEN PROGRESSIVELY AGING EGGS ARE 

 FERTILIZED BY SPERM OF VARYING AGES. Toxopneusles. 



by the one male, gave a decreasing per cent, of cleavage with age, 

 until the germ cells were 64 minutes old, when only o, i, o and I 

 per cent, of the eggs of each of the females cleaved. The eggs 

 were allowed to age further until they were 209 minutes old, 

 when they were fertilized by freshly liberated sperm, and cleavage 

 rose to 8, 85, 70 and 10 per cent, respectively. This was 423/2 

 per cent, greater than the previous observation. It was clear 

 that the failure to cleave when 64 minutes old was due to the 

 almost complete deterioration of the sperm. It is not clear 

 from this experiment how much the eggs have deteriorated. For 



