y 



Species and Varieties 



Their Origin by 

 Mutation 



Lectures delivered at the University of California 



by 



Hugo DeVries 



Professor of Botany in tfie University of Amsterdam 



Edited by 

 Daniel Trembly MacDougal 



Assistant Director of the New York Botanical Garden 



CHICAGO 

 The Ooen Court Publishing Company 



LONDON 

 Kegan Paul, Trench, Triibner & Co., Ltd. 



1905 



