198 ZOOLOGY 



by the selection and isolation of the minor varieties 

 could these be established as permanently differing 

 strains. 



References 



JENNINGS, H. S. "Heredity, Variation, and the Results of Selection in the 



Uniparental Reproduction of Difflugia Corona." Genetics, September, 



1916. 

 JENNINGS, H. S. " Modifying Factors and Multiple Allelomorphs in Relation 



to the Results of Selection." American Naturalist, May, 1917. 

 SPILLMAN, W. J. "Application of Some of the Principles of Heredity to 



Plant Breeding." Bulletin 165, Bureau of Plant Industry, United States 



Department of Agriculture. 



