Xvi PREFACE TO THE THIRD AMERICAN EDITION 



mentioned, and those pages that bear citations of this name are indicated 

 by full-face type. 



A note on the form of citation employed in this volume, and a selected list 

 of books bearing on plant physiology, are added after this preface. It is 

 hoped that these additions, as well as the citations of the book itself, may prove 

 serviceable to those who wish to acquire familiarity with the far-flung literature 

 of a subject that embraces the principles of many separately named sciences, 

 that brings into a single narrative such topics as ionization, adsorption, photo- 

 synthesis, fermentation, the forcing of azalias and the keeping-qualities of 

 apples. 



Editor. 

 Laboratory of Plant Physiology 

 of the Johns Hopkins University. 

 Baltimore, November, 1926. 



