230 PROBLEMS OF FERTILIZATION 



exert no fertilizing effect. I may refer here also to the 

 data with regard to other animals already presented 

 concerning the fertilizable condition of the ovum 

 (pp. 139 L), which show that the loss of fertilizing power 

 may be exceedingly rapid and certainly not connected 

 with a loss of vitality on the part of the eggs. These 

 data are most readily understood on the assumption 

 of loss of agglutinating substance on the part of the 

 egg. 



Just (1919^) has found also in the case of Echina- 

 rachnius that the production of the sperm-agglutinating 

 substance is an index of the fertilization capacity of the 

 eggs; immature eggs incapable of fertilization produce 

 none of it; ripe eggs washed in sea- water until they 

 no longer give the agglutination reaction are incapable 

 of being fertilized, and during the washing process loss 

 of capacity for fertilization runs parallel to loss of agglu- 

 tinating substance; f ertilized eggs have lost their ag- 

 glutinating substance, as have those with membranes 

 fully formed artificially. Those eggs that are highest in 

 agglutination capacity fertilize most readily and produce 

 the most vigorous larvae. 



The conception that agglutination of the sperma- 

 tozoon to the egg is a necessary factor in fertilization 

 may be understood in one of two senses: either that 

 such intimate association is needed for the further 

 action of the spermatozoon, whatever that may be, or 

 in the more special sense that the agglutinating sub- 

 stance is also the substance that activates the egg, and 

 that it is set in operation by the spermatozoon. In 

 favor of the latter more special interpretation is the 

 fact that spermatozoa may enter eggs devoid of agglu- 



