PREFACE TO THE ENGLISH EDITION 



ON account of the importance of Professor Pfeffer's new ' Pflanzen- 

 physiologie ' it has been considered advisable to produce an immediate 

 translation without waiting for the appearance of the second volume, 

 especially since no translation of the first edition has ever been published. 

 It is, moreover, hoped that a still shorter interval may elapse between 

 the appearance of the second volume and of its translation. The 

 difficulty of the original German has necessitated the exercise of a 

 certain freedom in the process of translation, but an exact interpretation 

 of the original has been given throughout, and all additions, as well as 

 references to the more recent literature, have been inserted in brackets. In 

 those sections, however, of which I had direct personal knowledge, a few 

 slight alterations have been made without any special indication of these 

 being considered necessary. The question of terminology becomes of 

 great importance in the translation of a work which definitely introduces 

 several new principles to botanical physiology, but this has been accom- 

 plished practically without the introduction of any new terms. A short 

 foot-note has been added, whenever necessary, explaining the reasons why 

 of two pre-existent terms one has been selected in preference to another. 



The whole of the proofs have been submitted to Professor Pfeffer's 

 approval, and in addition they have been subjected to thorough and 

 systematic revision by Professor Reynolds Green. I am under a deep 

 obligation to Professor Green for the valuable aid which he has rendered 

 throughout, and which has materially enhanced whatever merit this book 

 may possess. I must also record my indebtedness to Professor Muirhead 

 and Dr. Church for numerous valuable suggestions and criticisms. 



ALFRED J. EWART. 



BOTANICAL DEPARTMENT, 

 OXFORD, October, 1899. 



