Vlll PREFACE. 



lation was published in 1887 by the Clarendon Press 

 under the title Lectures on the Physiology of Plants.] 



Gesammelte Abhandlungen uber Pflanzen-Physiologie 

 von Julius Sachs. Leipzig, Engelmann. Band i. 1892, 

 Band IT. 1893. [This is referred to in the text as Sachs' 

 Collected Papers] 



I gladly take this opportunity of expressing my thanks 

 to Mr F. F. Blackman, Lecturer in Botany in the Uni- 

 versity, for much valuable help in the arrangement of the 

 experiments in Part I. Also to the Cambridge Scientific 

 Instrument Company for the use of the cliches for Figs. 25 

 and 26. 



FRANCIS DARWIN. 



BOTANICAL LABORATORY, CAMBRIDGE. 

 February, 1901. 



