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 



cA- 



Second Edition, 

 Corrected and Revised 



CHICAGO 

 The Open Court Publishing Company 



LONDON 

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



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