TRANSLATOR'S PREFACE 



In presenting this book to the English pubHc my 

 sincere thanks are due to my friend Miss E. I. M. 

 Boyd, M.A., who kindly undertook the revision 

 of the MS., and has shown the closest interest in 

 the translation and its publication. 



I should like also to acknowledge a debt of 

 gratitude to Professor Seward of Cambridge, and 

 Professor Vinogradoff of Oxford for their kind 

 help in regard to the publication of the book. 



My best thanks are due to Mr. D. Thoday, 

 of Trinity College, Cambridge, Lecturer in Plant 

 Physiology in the University of Manchester, for 

 his valuable assistance in the matter of scientific 

 revision and the correction of proofs. 



A. Cheremeteff. 



St. Petersburg, 

 November igil. 



