EGG SECRETIONS OF ARBACIA AND ASTERIAS 



481 



TABLE 8 

 Inhibition of cleavage by fat extracted from eggs 



table 8, 5 cc. of Arbacia eggs and sea-water were allowed to stand 

 with 1 cc. of this solution ten minutes before the addition of the 

 sperm. In 4, the sperm stood in the solution ten minutes before 

 eggs were added. In both cases, fertilization was inhibited. 

 Tests with iodine show that this extract contains an unsaturated 

 fatty acid, probably similar to that which forms about 30 per cent 

 of the phosphatide in Asterias eggs (Mathews, '13). 



Lillie found ('14) that Arbacia blood likewise blocks sperm 

 fertilization in the same species. My confirmatory experiments 

 are given in table 9. The ' serum' used was obtained by filtering 

 the perivisceral fluid, after it had stood long enough to clot. 

 It will be noted that boiling the serum sometimes removes the 

 inhibitor. 



Since Arbacia serum does not affect the agglutinating power of 

 fertilizin and since its ability to inhibit development of the egg 

 can be overcome by excess of fertilizin, Lillie concluded that block 

 in this case was produced by occupancy of the ovophile group. 

 The following experiment shows clearly that the sperm is not 

 affected in this block. Arbacia eggs were left standing in blood 

 of the same species for fifteen minutes. Then they were washed 



TABLE 9 



Inhibition of cleavage by Arbacia serum 



