48 



ROBERT RIKMENSPOEL 



33 



41 



43 



35 37 39 



TEMPERATURE , °C 

 Fig. 15. Temperature variation of v for four ejaculates from one bull. 



the data obtained from four ejaculates of the same bull. In the range 

 33^41 °C the temperature coefficient is approximately constant; an 

 optimum is apparently reached around 43 °C. This was also observed 

 for sperm of other bulls. Statistical analysis (kindly performed by 

 Dr. B. de Groot), showed that the ejaculates from each bull could 

 be "pooled 1 ' in calculating a temperature coefficient for v. These 

 coefficients are shown in Table III. Since the standard deviation of 

 dv/dt is about 0.5 micron /sec/ °C, these values do not clearly indicate 

 individual specific coefficients for each animal's sperm. 



Table III. Average temperature coefficient for four different bulls in the 

 range 33-4 1°C 



Bull 



Number of Ejaculates 



Temperature Coefficient 



/x/sec/°C 



D 23 

 W 1 

 R 2 

 A 10 



4.0 

 3.8 

 3.4 



2.2 



Aging of Sperm Cells. Samples taken at regular intervals from semen 

 stored at 4°C were used for measurements, at 37 °C, of velocity v and 

 concentration c of normally moving cells. Both these properties were 

 found to decrease exponentially with time, as illustrated in Figs. 16 

 and 17. The half-life of c is much smaller, however, than that for v. 



