198 



EDWIN J. COHN. 



initiating the development of the egg. This implies that what is 

 true in parthogenesis is also true in normal fertilization. R. S. 

 Lillie (Lillie, R. S., 1916) has quite beautifully shown that the 

 product of the concentration of the parthenogenetic agent and 

 the length of time during which it is necessary to subject eggs to 

 the agent in order to initiate development is a constant. The 

 evidence that has been presented strongly suggests a similar 

 quantitative relation in fertilization. 



TABLE X. 



THE RELATION BETWEEN THE CONCENTRATION OF THE SPERM AND THE PERCENTAGE 



OF EGGS THAT ARE FERTILIZED. 



VIII. THE EFFECT OF THE CARBON DIOXIDE CONCENTRATION 

 UPON THE ACTIVITY AND UPON THE LONGEVITY 



OF SPERMATOZOA, 



The effect of increasing the carbon dioxide concentration of 

 the suspension is to increase the length of life of the spermatozoa. 



