28 EGG AND SPERM SUBSTANCES 



In view of its stimulatory action on sperm motility it might be 

 expected that egg water would also increase sperm respiration. 

 This is indeed the case in the sea urchins Echinus escidentiis 

 (Gray, 1928; Carter, 1930, 1931; Vasseur, 1949b), Strongtjlocen- 

 trotus droehachiensis ( Vasseur, 1949b ) , and the gastropod Mega- 

 thura (Tyler, 1948a; Krauss, 1950a). However, in some other 

 forms, notably Arbacia punctulata (Hayashi, 1946), S. purptira- 

 ttis (Tyler, 1948a; Spikes, 1949a), Echinus (Psanimechinus) 

 7niliaris (Gray, 1928; Carter, 1930, 1931), Lytechinus variegatus 

 (Greenberg, unpublished), and L. pictus (Spikes, 1949a), egg 

 water fails to increase sperm respiration. Indeed egg water treat- 

 ment may actually reduce the rate of oxygen uptake of the sperm 

 of some sea urchins (e.g., Lytechinus, Spikes, 1949a; Arbacia, 

 Hayashi, 1946). Or the egg water may simply delay the usual 

 rapid fall in respiratory rate characteristic of sea water suspen- 

 sions of sperni (e.g., P. miliaris. Gray, 1928; Carter, 1931). Finally 

 starfish egg water has no effect upon either sperm motility or 

 respiration (Metz, 1945; Metz and Birky, unpublished). 



The agent in egg water which affects the respiration of sperm 

 is usually assumed to be fertilizin. This view is supported by ex- 

 periments (Spikes, 1949a) showing that the agglutinating action 

 and respiratory effects ( in this case a lowering of oxygen uptake ) 

 of sea urchin egg water are destroyed simultaneously by ultravi- 

 olet irradiation. On the other hand, heating at 126° C. destroys 

 the sperm agglutinating action but actually enhances the respira- 

 tion increasing action of E. esculentus egg water. Egg water 

 autoclaved in acid (pH 0.5) failed to increase the oxygen uptake 

 of the sperm (Vasseur, 1949b; see also Biehg and Dohrn, 1950). 



The discovery (Tyler and Rothschild, 1951; Tyler, 1953; Roths- 

 child and Tyler, 1954) that metal binding or chelating agents 

 increase the motility of sperm may explain the motility increasing 

 action of egg water. As suggested by Tyler and Metz ( 1955), sea 

 urchin fertilizins may possess metal binding action. Low molecular 

 weight substances in egg water and split products of fertilizin 

 may also be found to have this effect. Finally, appreciation of the 

 possibility of this mode of action should materially aid in a further 

 identification of the active agent or agents in egg water. 



