EFFECTS OF AGING UPON GERM CELLS. 



3 8I 



fertilized by the one male, when the germ cells were 20 minutes 

 old. Fertilization membranes first appeared in the three groups 

 of eggs as follows, 3^, 1% and i% minutes respectively. When 

 the germ cells were 80 minutes old, they appeared in 2%, i%, 

 if minutes; when 140 minutes old, i%, i^ and I minute; 

 when 280 minutes, %, i% and I minute. 



In the other experiments similar results were obtained, i. e., 

 uniform or nearly uniform rate of membane formation, when the 

 eggs of one female were fertilized by different sperm, and frequently, 



TABLE 1 1. a. 



SHOWS CHANGE IN RATE OF MEMBRANE FORMATION WITH AGE, OF EGGS OF 

 DIFFERENT FEMALES. Toxopneustes. 



N = no membrane in 10 minutes. 



