species and Varieties 



Their Origin by 

 Mutation 



Lectures Delivered at the University of 



California 



by 



Hugo DeVries 



Professor of Botany in the University of Amsterdam 



Edited by 



Daniel Trembly MacDougal 



Director Department of Botanical Research, Carnegie Institution 



of Washington 



Second Edition, 

 Corrected and Revised 



CHICAGO 

 The Open Court Publishing Company 



LONDON 

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



1906 



