33 2 MYRA MELISSA SAMPSON. 



The fact that loss of fertilizing power of the sperm occurs rapidly 

 and precedes loss of motility has suggested the idea that the 

 spermatozoon carries a fertilizing substance which may be lost 

 in sea-water; and this has led to various attempts, of which 

 this is the most recent, to isolate such a substance and to produce 

 development of ova of the same species with it. In this investi- 

 gation filtrates and dialyzates of sperm suspensions in sea-water 

 have been obtained which initiate development of specific ova, 

 although the development is incomplete. 



It is not surprising to find that concentrated sperm suspensions 

 exposed to egg-secretions of a foreign species, that extracts of cells, 

 egg-secretions, and blood cause cytolysis of alien ova, "since it 

 is recognized that something present in mammalian blood serum 

 cytolyzes cells of unrelated animals," Loeb (1913). Sperm killed 

 by heat, extracts of cells, and blood serum have no activating 

 effect on ova of the same species. Specific egg-secretion ("egg- 

 water") has no effect on ova of Nereis, but according to Glaser 

 (1915) and Woodward (1918) does produce incomplete activation 

 of ova of Asterias and Arbacia. Prolonged exposure of ova is 

 necessary, and Lillie and Just (1924) have suggested that there 

 are extraneous parthenogenetic factors present in the egg-water 

 employed. 



Careful tests of all the sperm filtrates and dialyzates used in 

 this investigation indicate that the preparations do not contain 

 living sperm or fragments of them. The ova employed are not 

 normally parthenogenetic. Controls give evidence that no 

 substance derived from filters or dialyzers is accountable for 

 the results obtained; and factors which might produce partheno- 

 genesis: abnormal specific gravity, abnormal hydrogen ion 

 concentration, and excess of carbon dioxide, are lacking. The 

 preparations contain carbon but insufficient nitrogen to be 

 detected even by microchemical methods. No lipolytic enzyme 

 could be detected. The preparations are not colloidal; and all 

 attempts to obtain precipitates from them by means of alcohol 

 or the reagents used by Robertson (loc. cit.} and Woodward 

 (he. cit.) failed. Sperm filtrates and dialyzates activate ova 

 rapidly and this property is not destroyed by boiling. The 

 effect produced is evidently due to a special physiological 

 activator derived from sperm of the same species. 



