586 FRANK R. LILLIE 



lyzer by the sperm because polyspermy does not increase the rate 

 of development over the normal. But he has neglected to note 

 that the same argument apphes to his lysin theory; if this theory 

 were correct we should expect that polyspermy would increase 

 the cortical cytolysis above the normal, and result in an unusually 

 distended fertilization membrane; but this is not the case; mem- 

 brane formation is not excessive, so far as observed, in polyspermic 

 eggs. Yet the lysin theory requires that this should be the case. 



It is also inconceivable that a lysin could act effectively in such 

 high dilutions as the respective bulks of spermatozoon and ovum 

 render necessary. Wilson estimates the bulk of the spermatozoon 

 at about 1/400,000 that of the egg in the sea-urchin. The sperm 

 head is not visibly diminished after entrance so it would be un- 

 reasonable to suppose that more than 10 per cent of its substance 

 has been used in membrane formation. The lysin theory supposes 

 that a spermatozoon cytolyzes a bulk of 4,000,000 times its lysin 

 content! Not only so, but inasmuch as it is introduced at one 

 point the lysin must diffuse with a speed and evenness that renders 

 it effective simultaneously, and very quickly, at all points on the 

 surface of the egg. This conception seems to me to be inconceiv- 

 able, for the theory of lysin action presupposes a union molecule 

 for molecule over the affected surface. We should also have a 

 large spermatozoon for large eggs and a small spermatozoon for 

 small eggs on the basis of a lysin theory, which is not the case. 



These considerations are arguments not only against the lysin 

 theory but also against any theory that presupposes that the 

 spermatozoon is the bearer of a substance acting directly in caus- 

 ing formation of the cortical changes of fertihzation.^ 



I may be allowed finally to point out that, even if some form of 

 sperm extract should be shown to be effective in the production 

 of the cortical change, such a result would be as consistent with 

 the theory of indirect action or activation of an ovogenous sub- 

 stance as with the theory of direct action and would be no argu- 

 ment against the preceding considerations. 



^ Although Professor Loeb has committed himself very definitely to the lysin 

 theory, he has not failed to note the theoretical possibility of the activation hypo- 

 thesis (son Loeb 1913, p. 235; earlier reference given here). 



