212 EDWIN J. COHX. 



substances that have been studied, and can best be understood 

 by analyzing the effect of egg water upon the physiological con- 

 dition of spermatozoa. That spermatozoa are activated to an 

 exceptional degree by a secretion from the egg has clearly been 

 demonstrated by the work of all of the investigators who have 

 been quoted. It may be that the fertilizing power of spermatozoa 

 that are added to eggs in sea water during this period of activa- 

 tion is increased in much the same way that the fertilizing power 

 of spermatozoa is increased for a short period of time by decreas- 

 ing the hydrogen ion concentration (increasing the alkalinity) of 

 sea water. If the sperm are added to eggs after they have be- 

 come inactive, the percentage of eggs that are fertilized depends 

 upon the degree of inactivity and the degree of reactivation 

 (such as is brought about by a transfer to sea water without a 

 high carbon dioxide tension) which the experimental conditions 

 afford. The sooner the sperm become inactive and the more 

 completely inactive they become the longer their life. Thus, 

 excepting for the initial period of activation, the effect of "egg 

 water" upon the length of life of the spermatozoon is essentially 

 that of a solution of optimal hydrogen ion concentration. The 

 hydrogen ion concentration of the "egg waters" that is most 

 effective in preserving the life of the sperm is precisely that of 

 the acidified sea water that best subserves the same function. 

 In the "egg water" this hydrogen ion concentration is reached 

 as a result either of the carbon dioxide produced by eggs and 

 eliminated into the "egg water" or that produced by sperma- 

 tozoa during the period of their greatest activity. 



XII. SUMMARY. 



1. The total available energy of spermatozoa, as measured by- 

 total carbon dioxide production, is a constant. 



2. The rate at which the total available energy is expended is a 

 function of the activity and an inverse function of the length of 

 life of spermatozoa. 



3. The activity and the length of life of spermatozoa is a func- 

 tion of the temperature, and of the hydrogen ion concentration 

 of the suspension. Up to a certain point decreasing the tempera- 

 ture or increasing the hydrogen ion concentration decreases the 



