42 



ROBERT RIKMENSPOEL 



I SEC. 

 Fig. 9. Record of a nonrotating cell passing over the aperture; head 

 and middle piece plus tail can be roughly distinguished. 



relation (2), v = 1.2- b~, and approximating the tail wave to be 

 sinusoidal, the expected value for / can be calculated (Rikmenspoel, 

 1957b). The relation is shown in Fig. 10. A model experiment was 

 performed to check this approximation; films were projected on a 

 screen on which the aperture was represented, and / was measured 

 of the sperm "passing" over it. These data are represented in Fig. 10. 

 In view of the approximate nature of the calculated line, the slight 

 discrepancy is not disturbing. An error of 10 to 12% (Rikmenspoel, 

 1957b) is to be expected as a result of several factors in measuring 

 the velocity of a cell passage: (1) uncertainty in reading the beginning 

 and end of passage, (2) blurring of the cell image by the limited 



Fig. 



40 80 120 160 



VELOCITY ((im/SEC.) 

 10. Distance / covered by a rotating sperm during passage over 



the aperture, as a function of the velocity v of the cell. The dotted line 

 represents the value of / from an approximate calculation. 



