PREFACE TO THE FIFTH RUSSIAN EDITION ix 



ism, undoubtedly represents one of the relics of mechanistic 

 traditions in science. With every new edition, it dissatisfied 

 me more and more until finally I decided to reorganize funda- 

 mentally the whole plan of the textbook. 



In the present fifth edition, the discussion is arranged in such 

 a manner as first of all to acquaint students with the general 

 physicochemical foundations of the plant, with its chemical 

 composition, and with its mechanisms of digestion and metab- 

 oHsm. After these introductory chapters, we pass to a discussion 

 of some of the more important vital functions, such as respiration 

 and growth, which are most clearly manifested already from the 

 first growth stages — the germination of the seeds. 



This is followed by an examination of the primary synthesis 

 of organic substances, which forms the most characteristic 

 pecuharity of the. green plants, the process of absorption of 

 mineral elements necessary for growth, and the questions closely 

 related to these processes, viz., the water relations and trans- 

 location of substances through the plant. This part acquaints 

 the students with the most important physiological functions, 

 which form the basis of the vegetative phase of plant life and 

 of the period of increase in size and of the accumulation of organic 

 substance. 



In the following chapters, the plant is discussed as a unit 

 organism in v/hich all the parts and all the processes taking 

 place in them are closely interrelated. These chapters are 

 devoted to an examination of the resistance of plants to unfavor- 

 able external agents, to problems of interrelations of different 

 parts of the plant, to questions of physiology of development and 

 reproduction and to seasonal phenomena in the life of plants. 

 The material contained in this final part of the course (Chaps. X 

 to XIV) has found as yet comparatively little room in text- 

 books, and, indeed, available data in this direction are very 

 meager as compared with those contained in the first nine chap- 

 ters of this volume, which comprise the usual contents of text- 

 books on plant physiology. However, the great importance of 

 these problems for agricultural production has led me to devote 

 no less attention to these questions than to those of the nutrition 

 and growth of plants. 



In disposing the different parts of the course in such a sequence 

 as to begin with the processes most pronounced during the 



