SPERM-EGG INTERACTING SUBSTANCES, I 



31 



surfaces and sulphate groups in fertilizin. Attractive as this idea 

 may be, it is probably an over-simplification, if only because steric 

 factors play a dominating role in the specificity of antigen-antibody 

 reactions and, by analogy, might be expected to be important in 

 sperm agglutination. 



There are, of course, aquatic organisms whose unfertilized eggs 

 are not surrounded by an obvious shell of jelly. The best known 

 example is that of Nereis siiccinea, though there is no doubt that a 

 substance with similar properties to sea-urchin egg jelly diffuses 



TABLE 4 



Effect of homologous spermatozoa ofifucose content, in [xgltnl., 



of egg water (A. lixula), Monroy et al. {1954) 



out of unfertilized Nereis eggs. These eggs extrude jelly, which 

 has fertilizin-like properties, after fertilization. 



One obvious function of egg jelly in fertilization is to prolong 

 the life of the spermatozoon. This effect is not very specific and 

 can be reproduced by adding albumin to the sea water in which 

 the spermatozoa are suspended (Wicklund, 1954). As chelating 

 agents such as versene have the same effect (Tyler, 1953; Roths- 

 child & Tyler, 1954), it may be that, in this context, egg water 

 protects the spermatozoa from the adverse effects of small quan- 

 tities of heavy metals in sea water. Two lines of attack on the 

 problem of the reactions between spermatozoa and fertilizin might 

 repay further investigation: first, a careful investigation with the 

 electron micrograph into the morphology of spermatozoa before 

 and after treatment with multivalent and univalent fertilizin. 

 Care must be taken in such experiments to resist the temptation 

 to select and generalise from photographs which show interesting 

 structural changes, when others from the same suspension do not. 

 The spermatozoa of Nereis succinea would be particularly suitable 

 for such a study as Lillie (19 19) noted that the heads of agglu- 

 tinated Nereis spermatozoa are swollen and spherical. Secondly, 



