36 EGG AND SPERM SUBSTANCES 



Table II. Effect of pH on Fertilizin Agglutination of Patiria Sperm" 



" Of three samples from a Patiria miniata sperm suspension A served as a 

 control (pH 7.8), B was raised to pH 8.8 with O.lA'' NaOH, and C was raised 

 to pH 8.8 and then lowered to pH 7.3. Ten and 40 minutes after final pH 

 adjustments the suspensions were tested for agglutination with homologous 

 and heterologous fertilizins. Sample A failed to agglutinate. Sample B aggluti- 

 nated specifically at 10 minutes, but gave nonspecific reactions at 40 minutes. 

 Sample C agglutinated weakly, but specifically at 10 minutes, very weakly, if 

 at all, at 40 minutes. 



verted to the nonagglutinating, univalent form by ultraviolet 

 radiation (Metz, 1945). 



The experiments cited, then, show that the metal ions affect the 

 ability of starfish sperm to agglutinate with multivalent fertilizin. 

 The metals probably combine with and block the reactive sites 

 of most of the sperm surface antifertilizin. Such action implies 

 that strong anionic groups, SH groups, amino acid, or other 

 groups with a strong affinity for metal ions are essential constit- 

 uents of the "active sites" of starfish antifertilizin, and that these 

 groups must be free to combine with appropriate groups of fer- 

 tilizin. Evidence for such blocking action was obtained in a series 

 of absorption experiments. These showed that untreated starfish 

 sperm can bind fertilizin to a limited extent but that this fertilizin 



