186 LEONARD NELSON 



concerned with the transport of substances across cell membranes, 

 appears to be localized in the "spiral" sheath confining the flagellum 

 (Nelson, 1958a). The axial core is stabilized by cytochemical re- 

 agents used in the demonstration of cholinesterase, and is a logical 

 contender for the actin-like moiety of the contractile complex. Pro- 

 jections from the peripheral fibers extend inward toward the axial 

 fibers in a manner reminiscent of the Huxley-Hanson sliding fila- 

 ment pattern. However, while only 3-5% localized shortening may 

 be required for the propagation of the sinusoidal wave, we may still 

 have to invoke molecular folding of the "actinoido-spermosin" com- 

 plex. Even though all the loci could not have been anticipated in de- 

 tail, the results thus far permit the construction of an effective, yet 

 sufficiently flexible framework for deferred incorporation of unas- 

 signed components and for verification of tentative speculations. 



REFERENCES 



Afzelius, B. 1959. Electron microscopy of the sperm tail. Results obtained 

 with a new fixative. /. Biophys. Biochem. CytoL, 5, 269-278. 



Bishop, D. W. 1958a. Relaxing factors in ATP-induced motility of sperm 

 models. Anat. Record, 132, 414-415. 



Bishop, D. W. 1958b. Mammalian sperm cell models reactivated by ATP. 

 Federation Proc., 17, 15. 



Bradfield, J. R. G. 1955. Fibre patterns in animal flagella and cilia. Sym- 

 posia Soc. Exptl. Biol., 9, 306-334. 



Burnasheva, S. A. 1958. Properties of spermosin, a contractile protein, in 

 sperm cells. Biokhimiya, 23, 558-563. 



Cleland, K. W., and Lord Rothschild. 1959. The bandicoot spermato- 

 zoon: An electron microscope study of the tail. Proc. Roy. Soc. (Lon- 

 don), B150, 24-42. 



Engelhardt, V. A. 1946. Adenosinetriphosphatase properties of myosin. 

 Advances in EnzymoL, 6, 147-191. 



Gibbons, I. R., and A. V. Grimstone. I960. On flagellar structure in cer- 

 tain flagellates. ./. Biophys. Biochem. CytoL, 7, 697-716. 



Gray, J. 1928. Ciliary Movement. Cambridge University Press, Cambridge, 

 England. 



Hartree, E. F., and T. Mann. 1959. Plasmalogen in ram semen, and its 

 iole in sperm metabolism. Biochem. [., 71, 423-434. 



Hayashi, T., R. Rosenbluth, P. Satir, and M. Vozick. 1958. Actin partici- 

 pation in actomyosin contraction. Biocliim. et Biophys. Acta, 28, 1-8. 



Lardy, H. A., R. G. Hansen, and P. H. Phillips. 1945. The metabolism of 

 bovine epididymal spermatozoa. Arch. Biochem., 6, 41-51. 



