BIOMOLECULAR ASPECTS OF SPERMATOZOAN MOTILITY 



223 



Fig. 13. Reversible contraction of flagellar protein. 



ing reagents and the necessary molecular architecture is intact, both 

 flagellar gels and extracted sperm models will work automatically. 

 Since one of the problems of flagellar motion is the transport of sub- 

 stances through the attenuated 9 plus 2 arrangement, it may be that 

 even here there is little need for a semipermeable membrane; the 

 permeability of the flagellar surface may be a function of the "con- 

 tractility" of the proteins. Providing that the enzymes (or the sub- 

 strate-splitting moieties) are retained strategically and the contractile 

 arrangement is related and continuous, the flagellum will continue 

 to beat, and the reacting substances will be transported hydraulically, 

 just so long as the substrate is available and the requisite ions are in 

 the vicinity. Overall control of the motion of the flagellum might be 

 exercised by "pinching oft" the supply of salts or substrate in a stra- 

 tegic way. 



