SPECIFICITY IN FERTILIZATION 195 



ence of the jelly many eggs form membranes but fail 

 to segment owing to failure of the spermatozoon to 

 penetrate. Loeb suggests that the latter phenomenon 

 may therefore be due to agglutination of the starfish 

 sperm to the jelly. 



We gain here a hint that will be further developed 

 in the section on the mechanism of fertilization, viz., 

 that the specific factor in fertilization may concern an 

 agglutination reaction between egg and sperm, as the 

 writer earlier maintained. 



In 1906 Godlewski attempted to fertilize sea urchin 

 eggs with sperm of starfish, holothurians, and brittle 

 stars by Loeb's method without success. However, he 

 succeeded in fertilizing eggs of the same genera of sea 

 urchins with the sperm of Antedon rosacea (crinoid) by 

 the same method. The fertilizations succeeded best in 

 the alkaline sea-water with a high concentration of 

 sperm; but some eggs were fertilized when first exposed 

 and then washed in normal sea-water, a fact that shows 

 the main effect of the alkali to be on the egg. A few 

 eggs might develop to normal plutei, thus exhibiting a 

 purely maternal inheritance, in spite of the fact that 

 the sperm nucleus fused with the egg nucleus and no 

 elimination of chromatin could be demonstrated in 

 later stages. 



Tennent (1910) also succeeded in fertilizing sea 

 urchin eggs with sperm of different echinoderm classes. 

 Thus the eggs of Hipponoe were fertilized with the 

 sperm of Ophiocoma (brittle star) and of Pentaceros 

 (starfish), and the eggs of Toxopneustes with the sperm 

 of Holothuria. The method employed was to allow the 

 eggs to stand two to three hours before adding the 



