PHYSIOLOGY OF THE SPERMATOZOON 123 



from either iso-agglutination. The adhesion of the 

 spermatozoa is permanent, not reversible, and if the 

 egg water be strong the spermatozoa are killed. More- 

 over, the blood of Arbacia produces the same effect on 

 Nereis sperm, as its egg water, whereas it is an indif- 

 ferent medium for the specific sperm. The conclusion 

 is therefore suggested that the "hetero-agglutinin" and 

 the "iso-agglutinin" of Arbacia egg water are different 

 substances. 



This can in fact be demonstrated in more than one 

 way. Thus an Arbacia egg water that originally acted 

 both on Arbacia and Nereis sperms was found to have 

 lost all effect on Nereis sperm after seventeen days, 

 whereas it retained undiminished its agglutinating 

 effect on its own sperm (Lillie, 1913). The non-specific 

 substance was destroyed by the chemical changes in 

 the egg water, but the specific substance remained. 

 It is also possible to precipitate out all of the Nereis- 

 active substance with Nereis sperm and leave the full 

 complement of iso-agglutinating substance. Thus a 

 sample of Arbacia egg water was found to have 800- 

 unit iso-agglutinating power; it had also a powerful 

 effect on Nereis sperm but was negative at one- 

 sixteenth dilution. The addition of two drops of a i 

 per cent sperm suspension of Nereis to i c.c. of the 

 egg water completely neutralized the Nereis active sub- 

 stance but left the original 8oo-unit strength of the iso- 

 agglutinating substance. The sperm of a teleost was 

 also found capable of neutralizing the hetero-active 

 substance, leaving the iso-agglutinating substance in- 

 tact. The hetero-active substance would thus appear 

 to be rather generally toxic to foreign sperm. It 



