382 



A. J. GOLDFARB. 



"wide differences when the eggs of different females ivere fertilized 

 by the one male. There was afar greater variation among the eggs of 

 different females than among the sperm of different males, or, putting 

 the matter in a slightly different way, the extent of variation in 

 development is conditioned much more by the eggs than by the sperm. 

 With these facts in mind, we may proceed with the examination 

 of the effect of age upon the membrane formation in physiologi- 

 cally "good," "moderately poor" and "poor" eggs. The data 

 are brought together in Tables 1 1. a and 1 1. b. 



TABLE 1 1. b. 



SHOWS CHANGE IN RATE OF MEMBRANE FORMATION OF AGEING EGGS AND SPERM. 



Arbacia. 



.TV = no membranes in the first 10 minutes. 



In the first group, containing physiologically good eggs, the rate 

 of membrane formation was accelerated with age. For example in 

 experiment 2, the eggs of the 3 females were fertilized by one 

 male when the germ cells were 20, 80 140, 210, 280, 370, 440 and 

 550 minutes old. The eggs of female number i, for instance, 

 formed their membranes at the above ages in 3^, 2%, i%, 

 1 34 and % minutes, and none after 370 minutes. The eggs of 

 female number 3 formed their membranes in 1^4, if, i, 



