SPERM FILTRATES AND DIALYZATES. 



which is apparently lost by spermatozoa in staling in sea-water. 

 If this is present in sea-water filtrates and dialyzates, it should 

 combine with the "agglutinin" of "egg-water." This was 

 tested as follows. The agglutinating unit strength of Arbacia 

 egg-water was first determined, Lillie (1914). Dilutions of such 

 egg-water with sperm filtrates and with sea-water were compared 

 as to their power to agglutinate fresh sperm suspensions and no 

 difference could be detected in the capacity of the two sets of 

 dilutions to agglutinate sperm. Either an insufficient amount of 

 the combining substance is present in the sperm filtrates or the 

 substance or substances present do not have the power to 

 combine with the agglutinin of the egg-water. 4 



The agglutinin does not pass through collodion sacs. If the 

 substance in sperm dialyzates is the substance postulated by 

 Lillie, egg-water dialyzed against a sperm suspension should lose 

 its agglutinating power more rapidly than a similar egg-water 

 dialyzed against sea-water. In experiments devised to test this 

 theory no difference in the rate of loss of agglutinin could be 

 detected. 



The "fertilizin" of Lillie in Arbacia egg-water may, according 

 to Woodward (1918), consist of two parts: an agglutinating and 

 an activating substance. The latter only passes through a 

 Mandler filter. This activates sperm of the same species, and 

 has the power of causing parthenogenetic development of ova 

 of Nereis limbata, Sampson (unpublished, quoted by Woodward) 

 and Woodward (1921). If its action is intensified by a fertilizing 

 substance given off by sperm, a combination of filtrates of sperm 

 and of egg-water should be more effective than either alone. 

 No such intensifying effect could be demonstrated in any of the 

 experiments devised to test this possibility. 



VIII. DISCUSSION. 



In Nereis limbata and in sea-urchins the fertilizable period of 

 the gametes is short. Causes for the brevity of this period have 

 been discovered for ova but not for spermatozoa, as indicated by 

 Lillie and Just (1924) in their recent survey of the subject. 



4 It should be recalled that some of the sperm remaining on the surface of the 

 filter mantles and in the dialyzing sacs are agglutinable and retain their fertilizing 

 power at the end of the periods of nitration and of dialysis. 

 23 



