SPERM MOVEMENT PROBLEMS AND OBSERVATIONS 27 



at doing the same ourselves, using dark-ground illumination? It, tor 

 example, someone were prepared to subsidize it, I would like to 

 commission a tremendously powerful electronic flash lamp for use 

 with the light microscope. Even with a small mercury arc lamp, I 

 recently saw some "bacterial flagella," about 0.1 micron in diameter, 

 on the surfaces of tick spermatozoa which, as some of you know, were, 

 until recently, described as moving exclusively backwards, without 

 any means of propulsion. Actually, their "bacterial flagella" do not 

 propel them. As an alternative to the electronic flash program, which 

 would also require electrical stimulation of fibrils or the use of 

 sperm models, is it ridiculous to consider the possibility of freezing 

 sperm bending waves and examining tails and their fibrils both with 

 the light and the electron microscope, to see if there is any geometri- 

 cal difference between a contracted and a relaxed segment? 



These ideas may seem fanciful and are no doubt wide of the mark. 

 But would there not have been similar scepticism ten years ago at the 

 idea of "seeing" ATPase on peripheral fibrils with the electron 

 microscope, as Nelson (1958) has done? 



CONCLUSION 



Why are we interested in sperm movement? Impressive answers to 

 this question could and doubtless will be given by our distinguished 

 speakers. A suspension of spermatozoa is one of the nicest assemblages 

 of cells with which one could work. They respire — at least I think 

 they do — though John MacLeod may have different views about 

 human spermatozoa; they glycolyze, though they usually fructolyze; 

 they have all the gadgetry which in other types of cells is usually 

 examined in slices of organs or with the aid of that instrument so 

 dear to the biochemist, the homogenizer; they contain interesting 

 compounds and enzymes to help them in doing their duty toward 

 the egg; parts of them are like, or are, muscle fibers so that sperm 

 tails may help us to learn how muscles contract; parts of them are 

 antigenic, which may help us to find out whether their tails contain 

 actomyosin, something-myosin or a new "muscle" protein; they are 

 easy but sometimes frustrating game for the electron microscopist; 

 they move in an obvious way, unlike most other cells, and therefore 

 tell us, visually, if they are alive (always assuming that if they don't 

 move, they are dead); they are concerned with some of the most im- 



