EFFECTS OF AGING UPON GERM CELLS. 21 



My own observations, still unpublished, extend and corroborate 

 Wasteneys's results. 



But to what extent was the change in permeability of the 

 cortical layer, with its train of events, responsible for the deterio- 

 ration of the eggs. If it was an important factor, it should be 

 possible experimentally to retard these cortical changes, and 

 hence correspondingly to increase the longevity and to retard the 

 deterioration of the eggs. Such experiments were made re- 

 peatedly and successfully, an account of which will appear later. 

 I mention these experiments merely to emphasize the fact that 

 there appears at present two methods by which physiologic 

 deterioration and "aging" may be controlled, namely, by retard- 

 ing or preventing either the metabolism, or the change in per- 

 meability of the eggs. 



By reducing the metabolism of the eggs, Lyon, Loeb and 

 Wasteneys retarded the deterioration of the eggs. By retarding 

 the cortical changes I have retarded the deterioration of eggs as 

 well. By a summation of both methods far greater control of 

 aging or deterioration was obtained. 



Both methods are closely related. A change in the cortical 

 layer induced a corresponding change in the metabolism of the 

 egg, and it is probable that the reverse obtains, namely a change 

 in metabolism is associated with a change in the cortical layer. 



This leads directly to the possibility urged by Loeb, Child and, 

 particularly in view of the unpublished work of E. J. Cohen, 1 

 that ageing and hence longevity of the germ cells is a function of 

 the rate of metabolic activity of the protoplasm of the egg or 

 sperm, the greater the rate of metabolic activity, the shorter the 

 life of the germ cell, and vice versa, the lower the rate of metabo- 

 lism the longer lived the germ cell. 



Hence eggs in sea water are longer lived than dilute concen- 

 trations of sperm, both of the same chronologic and physiologic 

 age. For the same reason eggs in sea water are shorter lived 

 than concentrated or dry sperm. For in this condition the 

 sperm are inactive, and hence lower metabolic rate. How far 

 the result is due to the greater metabolism on the one hand as 



1 The first study has since appeared in the BIOLOGICAL BULLETIN, Vol. 34, 3, 

 1918. 



