34 ILLINOIS ACADEMY OF SCIENCE 



i. e., which renders the combination of the sperm with the 

 agglutinating substance impossible. The presence of this sub- 

 stance may be demonstrated by methods that plasmolyze the 

 egg or extract its internal substances. If for instance, eggs 

 are deprived of the jelly in which they are normally embedded, 

 and which is heavily charged with agglutinating substance, in 

 order to get rid of excess of the agglutinating substance, and 

 are then divided into two equal lots, one of which is placed in 

 a certain quantity of sea-water, and the other in an equal bulk 

 of distilled water, it is found that plasmolysis takes place in 

 the distilled water, and internal substances are extracted from 

 the egg. The supernatant fluid from the distilled water is at 

 first more highly agglutinative than the sea-water, which con- 

 tains only the normal secretion of the eggs. But there is pres- 

 ent in the distilled water extract, a substance which tends to 

 inhibit agglutination, and in a short period of time distilled 

 water extract becomes entirely neutral. This is not merely an 

 effect of distilled water on the agglutinating substance, be- 

 cause the latter may be kept for a long period of time in dis- 

 tilled water without deteriorating, but it is due to the presence 

 of a body which actually destroys the agglutinating substance, 

 or combines with it, in such a way as to prevent its effect. 



These results suggest that in normal fertilization the com- 

 bination between the agglutinating substance and the sperm- 

 atozoon is essential, and that polyspermy is prevented by a 

 neutralization reaction between the two substances produced 

 by the eggs. I have therefore proposed the term fertilizin for 

 the sperm agglutinating substance, and anti-fertiliain for the 

 other. 



It would follow that eggs in which the fertilizin is removed 

 by any method should be incapable of fertilization. While it 

 has proved extremely difficult to completely dispose of the 

 fertilizin content of eggs, and to test this conclusion, it has 

 nevertheless been possible by repeated washings greatly to re- 

 duce the fertilization content of eggs and secure the demonstra- 

 tion that the capacity for fertilization is correspondingly re- 

 duced. 



Eggs w r hen once fertilized are incapable of fertilization, 

 that is to say the protoplasm of such eggs will no longer react 

 with the spermatozoa. Such eggs should therefore ex-hy- 

 pothese, be devoid of fertilizin content and this is the case. 



To sum up: It is shown that ripe unfertilized eggs of 

 Arbacia secrete a substance which produces a more or less 

 specific agglutination reaction with sperm of the same species. 

 Before acquiring this substance, i. e., before ripening, the eggs 



