PREFACE. 



A TRANSLATION of OePs " Pflanzenphysiologische Versuche," 

 by the author of this volume, was published in 1894, and the 

 entire edition was exhausted within a few months after its 

 appearance. A similar elementary text, " Experimental Plant 

 Physiology," was prepared at once and published in 1895, the 

 last copy of which was sold in October, 1901. Meanwhile the 

 " Practical Text-book of Plant Physiology," presenting a brief 

 outline of the entire subject, with details of experimental 

 methods suitable for the exact analyses requisite in research 

 work, has been brought, out. 



The present little volume has been arranged to replace the 

 "Experimental Plant Physiology" (1895) and to meet the 

 constantly increasing demand for a course in elementary demon- 

 strations which may be followed by beginners in the subject of 

 botany. Experimentation is purposely confined to the prin- 

 ciples capable of demonstration by the simplest methods, and 

 without the costly and complex apparatus of a fully equipped 

 laboratory. Furthermore, an arrangement of the book into a 

 number of courses has been made to meet the exigencies of in- 

 struction in schools of various types. 



I am indebted to Dr. C. C. Curtis, of Columbia University, 

 and to Dr. H. M. Richards, of Barnard College, for many valuable 

 suggestions and for their kindness in reading proofs. 



D. T. MAcD. 



New York Botanical Garden, 

 January, 1902. 



