MENDELISM AND SELECTION 



if such little units exist, they are indeed very 

 little as well as numerous, and by adding to the 

 effect of the larger ones they produce what 

 amounts to modification of them. 



BIBLIOGEAPHY 



CASTLE, W. E. 



1906. "The Origin of a Polydactylous Race of Guinea- 

 pigs." Carnegie Institution of Washington, Publication 

 No. 49, pp. 17-29. 

 JENNINGS, H. S. 



1909. " Heredity and Variation in the Simplest Organ- 

 isms." The American Naturalist, 43, pp. 321-337. 



JOHANNSEN, W. 



1909. "Elemente der exakten Erblichkeitslehre." G. 



Fisher, Jena, 516 pp. 

 DE VRIES, H. 



(See Bibliography to Chapter VI.) 



WOLTERECK, R. 



1909. " Weitere experimentelle Untersuchungen iiber Art- 

 veranderungen, speciell iiber das Wesen quantitativer 

 Artunterschiede bei Daphniden." Verh. Deutsch. Zool. 

 Gesellsch., pp. 110-172. 



