STUDIES IN THE PHYSIOLOGY OF SPERMATOZOA. 185 



carbon dioxide in these suspensions is afforded by the following 

 experiments, which are of two kinds, (i) The length of life of a 

 sperm suspension was either increased by decreasing the rate at 

 which the carbon dioxide produced by the sperm could diffuse 

 from the suspension; or (2) the length of life of the sperm sus- 

 pension was decreased by decreasing the rate at which the carbon 

 dioxide and hydrogen ion concentration of the suspension in- 

 creased. This again was attained in two w T ays. The procedures 

 and the protocols of these experiments will now be reported 



V. THE RELATION BETWEEN THE LENGTH OF LIFE OF A CON- 

 CENTRATED SPERM SUSPENSION AND THE RATE AT 

 WHICH THE CARBON DIOXIDE PRODUCED BY 

 SPERMATOZOA is ELIMINATED. 



i. Decreasing the Rate of Diffusion of Carbon Dioxide (Experi- 

 ments 31, 32, and jj). 



In these experiments a sperm suspension was divided between 

 vessels of different diameter. The area of the suspensions that 

 was in contact with the air, and consequently the rate at which 

 the carbon dioxide produced by the sperm escaped into the air 

 constituted the only variable. It was found that the sperm sus- 

 pensions from which the carbon dioxide could least rapidly diffuse 

 lived for the longest time as judged by the percentage of eggs 

 fertilized when spermatozoa from these vessels were added to 

 eggs in sea water as a function of time (Table V.). 



Two methods were employed of decreasing the rate at which 

 the carbon dioxide produced by spermatozoa increases the carbon 

 dioxide and hydrogen ion concentration of the suspension. The 

 procedure in the one (a) was essentially the reciprocal of that 

 employed in decreasing the rate of diffusion of carbon dioxide. 

 In the other method (&) the "buffer" (Henderson, L. J., 1908) 

 action of sea water and therefore the rate of neutralization of the 

 carbon dioxide was artificially increased. 



(20} Increasing the Rate of Diffusion of Carbon Dioxide. 

 In experiment 214 the sperm suspension was divided between 

 two shallow vessels. The one remained in contact with the air 

 of the room, while over the surface of the other a stream of carbon 



