C. B. METZ 31 



of filaments (Dan, 1954b). On the other hand, a high incidence 

 of filament formation is associated with a strong agglutinating 

 action of egg water in Asterias and Nereis (Metz and Morrill, 

 1955 ) . In fact in Asterias the two effects are related to the extent 

 that egg water fails to have either action in the absence of a metal 

 binding agent. 



Egg water treatment also results in a "loosening" and displace- 

 ment of the echinoderm sperm midpiece (Dan, 1954a; Popa, 

 1927; Rothschild and Tyler, 1955; Tyler, 1952). It is suggested 

 (Tyler, 1952) that this effect may be related to the normal sep- 

 aration of these parts that occurs during fertilization. 



Fertilizin Agglutination of Sperm 



The sperm agglutinating action of egg water was reported by 

 several early investigators (see Morgan, 1927, for review) but 

 it was not until Lillie's ( 1913a,b, 1919 ) classical studies on 

 Arbacia and Nereis that a possible relation between this effect 

 and the fertilization of the egg was fully appreciated. Lillie 

 termed the agglutinating agent of egg water jeHilizin. Subse- 

 quently others have employed a variety of terms for the same 

 agent.* 



Lillie (1913b) showed that fertilizin agglutination of sperm 

 was characterized by a high order of specificity, and this has 

 been confinned on a wide scale (e.g., Metz, 1945; Tyler, 1949; 

 Vasseur, 1951). Lillie (1913b) also found that the agglutinin 

 was used up or absorbed in the agglutination reaction (see also 

 Tyler, 1941; Metz, 1945; Monroy et al., 1954), and he first em- 

 ployed an analogy with antigen-antibody reactions to explain the 

 agglutination of sperm. More recently this analogy has been de- 

 veloped further, particularly by Tyler and his students ( see espe- 

 cially Tyler, 1941, 1948a, 1955; Spikes, 1949b; Metz, 1945). 



Mechanism of Agglutination. In keeping with modern im- 

 munological theory agglutination is considered to result from a 

 chemical reaction between two substances, antifertilizin on the 

 sperm surface and the fertilizin dissolved in egg water. The reac- 



* Fertilizin (Lillie, 1913a,b; Tyler, 1948a) - Gynogamone II (Hartmann 

 et al., 1940) = jelly coat substance (Runnstrom, 1949a). 



