STUDIES OF FERTILIZATION 581 



condition of the already fertilized eggs or those with membranes 

 Formed by other methods (p. 556). These cases have been suffi- 

 ciently discussed already. 



But there are two methods of blocking the mechanism according 

 to the hypothesis, which we have not found, viz.: 2 (supra) the 

 occupancy of the sperm receptors in such a way that these side- 

 chains are no longer free to unite with the spermophile group of 

 the fertilizin, which would result in loss of fertilizing power of 

 the spermatozoon ffig. 1, sector 4); and 3 (supra), viz.: occupancy 

 of the egg receptors, or molecules of the protoplasm with which 

 the fertilizin reacts (fig. 1, sector 5). The discovery of these 

 missing links in the theory would serve as strong confirmatory 

 evidence of its essential correctness. 



The latter of these two missing links remains purely hypotheti- 

 cal, but I think it is possible that the former may be represented 

 by the phenomenon of the antagonism of sperm suspensions of 

 different animal phyla as described first by Godlewski ('10 and 

 '11) and subsequently by Herlant ('12, a and h). 



These two authors give quite different interpretations of the 

 results. "While Godlewski, relying on the analogy of the an- 

 tagonistic action of heterogenous hemolytic sera, regards the 

 phenomenon as proof of Loeb's 'lysin theory' of fertilization, 

 Herlant is more conservative, and believes that the explanation 

 cannot be sought in any fundamental alteration of either sexual 

 element; but is rather to be found in a pm-ely 'humoral mechanism,' 

 (i.e., in the effect of substance accompanying the spermatozoa) 

 which he supposes to modify the physical state of the surface 

 of the eggs in such way that the spermatozoa cannot penetrate. 

 Herlant apparently overlooks the fact .that penetration of the 

 spermatozoon is not necessary for the cortical changes, as has 

 been shown both by Loeb ('09 and '13) amd myself ('12). There 

 is nothing in the results of either author inconsistent with the 

 idea, that the mechanism of inhibition in this case may be due to 

 what I have called, "occupancy of the sperm-receptors" as indi- 

 ated in sector 4 of the diagi'am. This may be taken to mean 

 merely such mutual action of the spermatozoa (or extractives 

 thereof) on each other as to inhibit the union with the fertilizin. 



