330 



MYRA MELISSA SAMPSON. 



were affected by a similar duration of exposure to some of the 

 same filtrate. 



TABLE VIII. 



A COMPARISON OF THE ACTION OF FILTRATES ON THE FERTILIZING CAPACITY OF 

 SPERM AND OF OVA OF Slrongylocentrotus purpiiratus. 



It is also possible that filtrates may interfere with the develop- 

 ment of fertilized ova. This proved to be true. The ova of 

 Arbacia punctulata and of Strongylocentrotus purpiiratus trans- 

 ferred ten minutes after insemination in sea-water to sperm 

 filtrates failed to develop normally, and within eighteen hours 

 the majority had cytolyzed. 



Summary of the Action of Filtrates as Factors in Fertilization- 

 Sperm filtrates produce changes in the eggs of the same species 

 which interfere with a normal fertilization reaction if the eggs 

 are inseminated in the filtrate. The changes produced by a 

 brief exposure are reversible; by a longer exposure irreversible. 

 Such filtrates prevent normal development of eggs previously 

 inseminated in sea-water. The changes are of such a nature 

 that the entrance of sperm is facilitated and polyspermy results. 



VII. TEST OF FILTRATES FOR A "SPERM-FERTILIZING AND 

 AGGLUTINABLE SUBSTANCE." 



Lillie (1919) has suggested that the spermatozoa bear a 

 fertilizing substance identical with the agglutinable substance 



