VI PREFACE 



critical presentation of all of the aspects of any part of the sub- 

 ject. The chief purpose of the author is to present practical di- 

 rections for the demonstration of the principal phenomena of the 

 physiology of the plant, and also details of experimental methods 

 suitable for the exact analyses requisite in research work. Cita- 

 tions of literature have been made by no single fixed rule. In 

 some instances reference is made to the most important, or recent 

 papers, or those which treat some phase of the subject not touched 

 upon in the present volume, or to those which give more detailed 

 methods of experimentation, or to those which suggest questions 

 needing further investigation. The appearance and translation of 

 the splendid treatise of Pfeffer renders the use of more space for 

 either discussion, or citation unnecessary. But little attention has 

 been given to the definition of terms, except when demanded by 

 conflicting usage, and by the introduction of a few new expressions. 



It is impossible to make any general survey of the subject 

 without being impressed with the constantly increasing amount 

 of attention which the physiology of plants is receiving in botanical 

 instruction, and the additions being made to the facilities for re- 

 search in this department of science. The increase in both direc- 

 tions has been most marked in America. 



The labor of preparation of the present volume has been 

 materially lessened by the cordial cooperation of a number of 

 botanists, and physiologists, which cannot be adequately acknowl- 

 edged here. Dr. C. C. Curtis, of Columbia University, has 

 revised a number of chapters of the manuscript, verified some of 

 the newer methods outlined, and made numerous valuable sug- 

 gestions from the results of his own researches, and extensive 

 laboratory practice ; Mr. J. E. Kirkwood, of Syracuse University, 

 and Dr. W. J. Gies, of the College of Physicians and Surgeons, 

 Columbia University, prepared the experimental directions for the 

 chemical analysis of the body of the plant as given in Chapter 

 IX., and read proof of the same and other sections of the book ; 

 Professor Geo. E. Stone, of Massachusetts Agricultural College, 

 outlined some of the experimental work upon the relations of 



