x Preface 



main is not to be laid to her, since I have sometimes leaned back 

 on superior official authority and had my own way. 



In the first announcement of the book it was said that keys, 

 similar in principle to those used in works on classification, would 

 be appended as aids to the reader in finding the explanations of 

 phenomena. These keys, however, have assumed such propor- 

 tions that it seems best to transfer them to a separate work. They 

 are now in process of elaboration in detail by another of my 

 associates, Miss Julia Paton, Fellow in Botany in Smith College, 

 and will presently appear as a synoptical handbook. 



Finally, I recall that in advising the reader to try as many 

 experiments as possible for himself, I said that practical guides 

 to experimentation would be suggested in the Preface. Un- 

 fortunately the one of these I consider the best, I am forbidden 

 by modesty to name, excepting that I may mention, as our friend 

 Mr. Dooley would put it in similar case, that it is entitled A 

 Laboratory Course in Plant Physiology, is published by Messrs. 

 Henry Holt and Company, and is written by myself. 



THE AUTHOR. 

 Smith College, 



March 15, 1913. 



