BIOMOLECULAR ASPECTS OF SPERMATOZOA N MOTILITY 195 



dividual cells. However, there is considerable variation in the activity 

 of different spermatozoa. In some cases, the swimming stage is replaced 

 by a longer period of oscillation — up to about 15 min. Inactive milt, 

 from unripe fish or as a result of contamination, usually contracted 

 when diluted with water, but this "inactive" material could usually 

 be extended or dispersed by the addition of NaCl, CaCL at pH 9.0, 

 or Mg + + at neutrality. Although the sperm in these experiments 

 tended to disperse as if they were viable, they did not, with few ex- 

 ceptions, swim or oscillate. After storage of viable milt, on the other 

 hand, sperm activity diminished or ceased but could be restored, partly 

 or completely, by the addition of electrolytes, particularly Ca+ + , 

 Mg++, Na+, and CI at an optimum pH of 8.5. K+ conferred only 

 feeble activity, and NH 4 + none at all. Some characteristic effects of 

 ions on the restoration of activity of these enfeebled sperm are shown 

 in the graphs in Fig. l)a-d. Among the substances conferring highest 

 activity, the most surprising was bone dust, which apparently has no 

 definable solubility product (Hodge, 1955). 



In all these experiments on sperm from about 1000 fish of the spe- 

 cies described, ATP (as a 0.003M solution at pH 7.0 with added 

 0.005yA/ MgCL,) did not have any effect on cell motility. On the other 

 hand, spermatozoa that had actively swum and had ceased to move 

 could be partially restored to motion by the addition of ATP. In some 

 cases, isolated cells were seen still oscillating several hours later. 



These results illustrate the dependence of this type of flagellum on 

 the surrounding medium. Increased mobility at pH above 7.0 has been 

 observed in many cells, although the maxima differ (Lardy and Phil- 

 lips, 1943). The effects of NaCl on sperm movement are well known, 

 but the relative effects of combinations of ions at different pH values 

 seem to have received less attention. Unlike mammalian sperm, fish 

 sperm have a short life in an environment that cannot be controlled 

 by the fish, so that the cell, and perhaps the flagellum alone, must be 

 "primed" for activity. Viable sperm can swim in water free of electro- 

 lytes, but once enfeebled or disturbed in any way, the cell cannot 

 make good the deficiency, and the necessary stimulus and support 

 must come from outside. Of all flagellated organisms and gametes, per- 

 haps the fish spermatozoon is least fitted for controlled and sustained 

 movement and may represent a much simpler arrangement than is 

 found elsewhere. 



