MASS PHYSIOLOGY OF SPERMATOZOA 



267 



Among reviewers of the fertilization problem there is general 

 agreement as to the importance of the analysis made by Cohn in 

 1 9 18. After demonstrating that fertilizing power of sea-urchin sperm 

 suspensions falls off more rapidly in dilute than in concentrated sus- 

 pensions, Cohn undertook the measurement of the carbon-dioxide 

 production in sperm suspensions of different concentrations by fol- 

 lowing the hydrogen-ion potential, with the results shown in Figure 

 26. The ordinates give the hydrogen-ion potential of the suspension 



PATl 

 P/il.2 



PAIA 



■Phl.^ 

 Phl.b 



Phi. 9 



P/tS.O 



/Af HOURS 



Fig. 26. — Diagram from Cohn (1918) showing the hydrogen-ion concentration of 

 sperm suspensions of different concentrations after different time intervals. 



in terms of pH; the abscissas, the time in hours. The concentration 

 of each suspension is given in the accompanying legend. The in- 

 crease in H-ion concentration is due to the carbon dioxide produced; 

 and in turn, the rate of production of CO2 is a function of the H-ion 

 concentration of the suspension; and, as would be expected from 

 these conditions, the rate of carbon-dioxide production of sperm 

 suspensions decreases with lapse of time. The length of functional 

 life as measured by the percentage of eggs fertilized by identical 

 concentrations of sperm under identical experimental conditions is 

 summarized in Figure 27. 



