EFFECTS OF AGING UPON GERM CELLS. 



403 



Retardation is another symptom of the deterioration not of the 

 sperm but of the eggs. 



CORRELATION OF CHANGES. 



I have shown firstly that the freshly liberated eggs of freshly 

 collected females of the same species varied considerably with 

 respect to size, jelly layer, membrane formation and cleavage; 

 secondly the range of variability for each of these types of changes 

 was ascertained ; thirdly, these changes were correlated ; fourthly, 

 by these correlated phenomena one could accurately and conveni- 

 ently ascertain the exact physiologic condition of the eggs of any 

 female, at any time. 



Freshly liberated eggs from freshly collected females could be 

 readily classified into physiologically "good," "poor" and "bad" 

 eggs, on the basis of the correlated phenomena, as follows: 



Perhaps one example chosen at random may make the matter 

 more definite. The freshly liberated eggs of Arbacia (Experiment 

 8-12) were practically normal in size, over 90 per cent, contained 

 the jelly layer, fertilization membranes were formed in 1 3/2 to 2 

 minutes, the cleavage was 95, 97, 96 and 94 per cent, in the eggs 

 of 4 out of 5 females. The eggs of the fifth female were larger 

 than the norm, less than 90 per cent, possessed jelly layers, no 

 membranes were formed upon fertilization and only 18 per cent, 

 cleaved. The eggs of the same females were tested by a second 

 male, and gave the same size and jelly count, as before, and mem- 

 branes appeared in 2, 2, 2^, 2^2 minutes respectively. The 

 cleavage count was 72, 69, 62 and 55 per cent. This retardation 



