SPERM MOVEMENT PROBLEMS AND OBSERVATIONS 15 



the frequency of rotation, and A' is a constant. It would be interest- 

 ing to compare the spatio-temporal geometry of the contraction- 

 relaxation sequences in the fibrils of the sperm tail necessary to ef- 

 fect displacements of both types, that is, make a working model. The 

 difference between the arrangement of fibrils in the mammalian and 

 invertebrate sperm tail may be connected with the alleged inability 

 of some of the latter to propagate helical waves. In mammalian 

 sperm tails there are two concentric rings of nine fibrils. In inverte- 

 brate sperm tails there is only one ring, each member of which ap- 

 pears to be double because each fibril is divided into two halves by 

 a septum. 



Bishop's observations (1958) on squid spermatozoa are analogous 

 to those of Gray, in that in both cases rotation about the long axis 

 is said to occur. But if I have understood him correctly, Bishop said 

 that squid spermatozoa can rotate about their long axis without 

 passing bending waves along their tails — he refers to "straight, other- 

 wise motionless" spermatozoa (1958, p. 1638). How do they manage 

 to rotate without passing spiral waves along their tails or planar 

 waves which periodically vary the angle between the plane of vibra- 

 tion and fixed reference axes? I can understand why the spermatozoa 

 might not move forward and in this sense be motionless, but not 

 how they can rotate with a straight tail. Perhaps Dr. Bishop will ex- 

 plain this point. In the same paper Bishop (1958) reports a most 

 interesting observation, that tired squid spermatozoa can be re- 

 juvenated by the addition of adenosine triphosphate (ATP) to the 

 sea water round them. At the time, this was and, probably, still is 

 the only proven case of ATP exerting its classical intracellular func- 

 tion when applied outside the cell membrane. ATP has, for example, 

 no effect in restoring the cyanide-poisoned sodium pump in the squid 

 giant axon when added to the surrounding sea water. But when in- 

 jected into the axon, the poisoned pump starts up again (Caldwell 

 et al., 1960). I suppose spermatozoa have a normal cell membrane? 

 Apart from the usual black line or two seen at the sperm surface in 

 electron micrographs, is there any evidence that they have? The fact 

 that bull spermatozoa do not seem to shrink or swell in anisotonic 

 media (Pursley and Herman, 1950; Rothschild, 1959) may indicate 

 that they have an atypical cell membrane. Could someone measure 

 the electric capacitance of the membrane to see if it is 1 fit/cm 2 } 



