PREFACE 



TO THE SECOND EDITION. 



The expanding margin of botanical knowledge and 



the trend of botanical thought have made necessary 



much revision and rewriting ; the original intention 



of providing a general introduction to the problems 



of plant metabolism, adequate as a foundation on 



which to base further study, has, however, been 



maintained. 



P. H. 



T. G. H 



January, 1929. 



PREFACE 



TO THE FIRST EDITION. 



In the preparation of the present volume on the 

 Metabolic Processes of Plants two alternatives were 

 presented : the one to give as full an account as 

 possible of the literature, the other to give such an 

 account as would form a basis for further study. 

 The latter, and more difficult task, was chosen ; for, 

 valuable though a digest of the relevant literature 



