50 



ROBERT RIKMENSPOEL 



Table IV. Half-life for the decrease in number of normally moving cells 

 during storage at 4°C 



Bull 



Number of Ejaculates Measured 



ti/2 (hours) 



W 1 

 D 23 

 A 10 

 R 2 



49 ± 9 



51 ± 14 



27 ± 3.5 



14 ± 1 



The half-life for the decrease in the number of moving cells shows a 

 definite individual specificity for each bull (Table IV). 



Dependency on pH. Although different ejaculates show a rather 

 large variation in dependence of mean velocity of normal sperm on 

 pH (van Duijn and Rikmenspoel, 1960), a sufficiently general pic- 

 ture can be obtained by averaging the pH over several ejaculates. 

 This is shown in Fig. 18. The average increase over the pH range 

 5.7-7.6 was dy/dpH = 10 ± 1 microns /sec/pH unit. 



100 



O 

 u 

 if) 



l> 



Fig. 18. Dependence of v on pH, averaged for several ejaculates. (Cour- 

 tesy of C. van Duijn, Jr.) 



