STUDIES OF FERTILIZATION. 



agglutinating power of the egg-water in question. This experi- 

 ment was tried twice with the general result that the action on 

 both kinds of sperm was gradually destroyed by franciscanus 

 sperm, but the heteroactive substance disappeared more rapidly. 

 Thus no clear cut result was obtained. 



The determined facts might conceivably find an explanation on 

 the assumption that the action of purpuratus fertilizin on fran- 

 ciscanus sperm varies with a state of aggregation of the pur- 

 puratus fertilizin. I do not, however, find such an explanation 

 satisfactory because under experimental conditions, apparently 

 identical, certain samples of purpuratus fertilizin show this effect 

 and another does not, and there is no comparable variation for 

 the iso-agglutination. 



The eggs used in the cross-agglutination experiment cited 

 previously (Table V.) were fertilized uniformly with francis- 

 canus sperm (10 units) with the following results: 



TABLE VI. 



COMPARISON OF CROSS-AGGLUTINATION AND FERTILIZATION. 



A second experiment in which the same eggs of six purpuratus 

 were used for cross-agglutination and cross-fertilization gave the 

 following results (Table VII.). 



TABLE VII. 



A SECOND EXPERIMENT ON CROSS-AGGLUTINATION AND FERTILIZATION. 



Cross Agglutination. Fertilized with/rana'scanus Sperm. 



1 strong 0.3 % segmented. 



2 " 7-4% 



3 " o 



4 " 0.2% 



5 " 14-9% 



6 . absent . o 



it 

 it 



