C. B. METZ 51 



Apparently, in dilute solution, egg antifertilizin can aid fertiliza- 

 tion to the extent that the "fertilization rate" of both normal and 

 jellyless eggs is increased (Hagstrom and Hagstrom, 1955). This 

 action was most pronounced when fertilization was performed in 

 the solution. This and the fact that the action was duplicated by 

 albumen suggests that the effect may have been upon the sperm. 

 It is probably due to a metal binding action of the egg extract. 

 Antifertilizin evidently facilitates the parthenogenetic action of 

 hypertonic sea water (Runnstrom, Wicklund, and Low, 1954). 



In several recent reports (Motomura, 1950b; Monroy and 

 Runnstrom, 1950, 1952; Wicklund, 1954b; Runnstrom, Wicklund, 

 and Low, 1954) agents from eggs which thicken, toughen, or 

 facilitate elevation of the fertilization membrane have been de- 

 scribed, and a possible relation of the active agent or agents to 

 egg antifertilizin has been suggested. Evidently the membrane 

 elevating factor differs from antifertilizin since the two effects 

 are associated with separate fractions in the ultracentrifuge and 

 have different heat labilities (Runnstrom, Wicklund, and Low, 

 1954). With regard to this effect it should be noted that metal 

 binding agents act on sperm to facilitate membrane elevation 

 (Tyler, 1953). 



The membrane toughening action appears to be associated 

 with pigment granules of the egg ( Monroy and Runnstrom, 1952; 

 Wicklund, 1954a). An agent with similar action is extractable 

 from fertilized eggs with weak (pH 4.5) acid (Motomura, 

 1950b). The membrane toughening and egg jelly precipitating 

 effects have not been separated. These may be different manifes- 

 tations of antifertilizin action. 



Upon treatment of eggs with iodosobenzoic acid ( Monroy and 

 Runnstrom, 1952 ) or anisotonic sea water ( Runnstrom and Mon- 

 roy, 1950; Wicklund, 1954a) varying degrees of cytolysis of 

 fertilized eggs are induced. Such cytolysis is associated with a 

 release of pigment from the egg, a thickening of the fertilization 

 membrane and sometimes a partial precipitation of the egg 

 jelly outside the fertilization membrane. These observations in- 

 dicate a release of the agent(s) responsible for membrane tough- 

 ening and jelly precipitation. They also suggest (Motomura, 



