344 HOMER W. SMITH AND G. H. A. CLOWES. 



condition in the mechanism of fertilization at this H-ion concen- 

 tration. In Asterias polyspermy occurs more or less uniformly 

 over a wide range extending from pH 7.2 to 9.8. 



We are indebted to Mabel T. Studebaker for the statistical 

 work in the experiments recorded in this paper. 



BIBLIOGRAPHY. 



1. Clowes, G. H. A., and Smith, Homer W. 



'23 Amer. J. Physiol., XLIV., 144. 



2. Loeb, Jacques. 



'15 Amer. Nat., XLIX., 257. 



3. Smith, Homer W., and Clowes, G. H. A. 

 '24 BIOL. BULL., XLVIL, 304. 



4. Smith, Homer W., and Clowes, G. H. A. 

 '24 BIOL. BULL., XLVIL, 323. 



5. Lillie, Frank R. 



'17 Problems of Fertilization. Chicago. 



