HISTORY OF THE FERTILIZATION PROBLEM 27 



upon the presence of a specific substance which is pro- 

 duced at the time of rupture of the germinal vesicle and 

 which disappears completely after fertilization. If this 

 substance be present in the egg in adequate amount the 

 egg can be fertilized, otherwise not. It may be obtained 

 in solution in the sea-water and recognized by its capacity 

 for agglutinating sperm suspensions of the same species, 

 in some cases at least. If it is thus possible to associate 

 the fertilizable condition of the ovum with a definite 

 substance, we have a base from which an analysis of 

 fertilization can be made. 



If the existence of such a substance be admitted, 

 it must operate either by activating some substance in 

 the spermatozoon, which is to be regarded as the effective 

 agent in subsequent changes, or we must regard it as the 

 effective agent which is transformed from an inactive to 

 an active state by some substance in the spermatozoon. 

 If we take the first alternative, we have no explanation of 

 parthenogenesis, whereas if we regard the egg substance 

 as the active agent, the explanation of parthenogenesis 

 proceeds along the same lines as that of fertilization. 

 Moreover, I have been able to show by an analysis of the 

 phenomenon of blood inhibition of fertilization that the 

 first point of view is untenable. 



This substance may therefore be called the fertilizing 

 substance, or fertilizin. By its reaction it is shown to 

 be a colloidal substance, not giving the usual protein 

 tests, and exhibiting some of the properties of a ferment, 

 as shown by Richards and Woodward. Fertilization 

 would thus be a three-body reaction between the sperm 

 receptors, fertilizin, and egg receptors linked in line; 

 and it is possible to show that inhibiting agencies may 



