140 JACQUES LOEB 



' fertilizin, ' • his theory concerning the role which this substance 

 plays in the fertilization and development of the egg will meet 

 with serious difficulties, 



7. It is shown that eggs which have been treated with a mineral 

 acid like HCl and which have permanently lost the power of 

 causing a cluster formation of the spermatozoa can nevertheless 

 all be fertilized with sperm of the same species and that the 

 rapidity with which the sperm fertilizes these eggs is equal to 

 that with which normal eggs are fertilized. When the acid used 

 was a fatty acid and when membrane formation occurred the eggs 

 also lost permanently their power of inducing cluster formation 

 but retained their power of being fertilized by sperm, provided 

 that the membrane was first torn. 



8. The supernatant sea water of the eggs of Strongylocentrotus 

 franciscanus will not induce cluster formation of the sperm of 

 Strongylocentrotus purpuratus; yet the latter sperm fertilizes the 

 eggs of franciscanus. The sperm of Asterias ochracea undergoes 

 no cluster formation in the supernatant sea water of Strongylo- 

 centrotus purpuratus, no matter whether the sea water is normal 

 or hyperalkaline although the starfish sperm readily fertilizes 

 most or all the eggs of Strongylocentrotus purpuratus in hyper- 

 alkaline sea water. 



9. The facts mentioned under paragraphs 7 and 8 prove that 

 the substance which is responsible for the cluster formation is not 

 necessary for the process of fertilization. 



