54 EGG AND SPERM SUBSTANCES 



1942), it is evident that the egg agglutinating action is not due 

 to basic protein. Hultin ( 1949 ) also ascribed the egg agglutinating 

 action of antifertilizin preparations to the nucleoprotein some- 

 times present in such solutions. However, the main activity of 

 antifertilizin solutions cannot be attributed to nucleoprotein 

 ( Metz and Tyler, independent unpublished studies ) because the 

 nucleic acid content is not related to the biological activity of 

 antifertilizin preparations. Thus one extract prepared by freeze- 

 thawing Arhacia sperm (egg agglutinin titer 16) gave positive 

 reactions with Schiff's reagent, both before and after hydrolysis, 

 no color with diphenylamine (Dische test), and no absorption 

 maximum at 260 m/n when diluted to 1/10. Two other prepara- 

 tions gave absorption peaks at 260 m/x when diluted beyond the 

 range of biological activity. Clearly, then, the egg agglutinating 

 action of antifertilizin is not dependent upon nucleoprotein. 



In other studies Motomura ( 1954, 1955 ) has prepared acid 

 extracts of acetone-precipitated echinoid sperm. The extracts 

 agglutinated eggs and sperm and precipitated with hen's egg 

 white. It seems most probable that Motomura's agent is also basic 

 protein. The writer has repeated Motomura's procedure and ob- 

 tained an agent which appears to be identical with the basic 

 protein extracted from sperm by less elaborate methods. 



Evidently, two agglutinins may be obtained from sperm. One 

 of these is a basic protein(s) of histone type (Hamer, 1955). It 

 agglutinates both eggs and sperm. The other is an acidic protein 

 containing very little if any nucleic acid. It agglutinates only 

 eggs. 



Although the egg agglutinating agent is not a nucleoprotein or 

 basic protein, the question may be raised whether it actually is 

 the spenii receptor substance, antifertilizin. Information on this 

 point might be obtained by consideration of the agent's source 

 and specificity. Extraction of the egg agglutinin with weak acid 

 (pH 3) results in swelling and partial dissolution of the sperm 

 head surface between the acrosome and midpiece (Tyler, 1949). 

 This indicates that the agent may have been removed from this 

 region of the sperm surface. The specificity has been examined 



