78 Specificity in Fertilization 



jelly which surrounds the egg of piirpuratus.'' It is 

 thus not impossible that the specificity which favours 

 the entrance of a spermatozoon into an egg of its own 

 species may consist in an agglutination between sper- 

 matozoon and egg protoplasm (or its fertilization cone) ; 

 and that this agglutination is favoured if the Coh or 

 Cca or both are increased within certain limits. 



Godlewski discovered a very interesting form of block 

 to the entrance of the spermatozoon into the egg which 

 takes place if two different types of sperm are mixed. 

 He had found that the sperm of the annelid ChcEtopteriis 

 is able to enter the egg of the sea urchin and that in 

 so doing it causes membrane formation. The egg, 

 however, does not develop but dies rapidly, as is the 

 case when we induce artificial membrane formation, as 

 we shall see in the next chapter. 



Godlewski found that if the sperm of Chcetopterus and 

 the sperm of sea urchins are mixed the mixture is not 

 able to induce development or membrane formation, 

 since now neither spermatozoon can enter ; blood has the 

 same inhibiting effect as the foreign sperm. The mix- 

 ture does not interfere with the development of the 

 eggs if they are previously fertilized.^ 



The phenomenon was further investigated by Her- 

 lant^ who found that if the sperm of a sea urchin is 



^ Loeb, Arch. f. Entwcklngsmech., 1914, xl., 310. 

 ^Godlewski, E., Arch. f. Entwcklngsmech., 1911, xxxiii., 196. 

 3 Herlant, M., Anat. Anzeiger, 1912, xlii., 563. 



