viii PREFACE TO THE FIFTH RUSSIAN EDITION 



Another feature distinguishing the course in agrophysiology 

 is the detailed discussion of questions of ecology, or the interrela- 

 tions between the plant and its surrounding medium. Without 

 a study of these interrelations, it is impossible to understand 

 thoroughly the life of agricultural plants or to conceive physio- 

 logically the different methods employed in cultivating plants. 

 For most of these cultural methods are not directed upon the 

 plant itself but affect it indirectly through altering environmental 

 conditions, mainly the soil. 



In the analysis of vital phenomena, plant physiology is based 

 principally on physics and chemistry. That is why courses in 

 these branches of science and especially in organic, physical, and 

 colloidal chemistry must be studied before a course in plant 

 physiology is undertaken. Sufficient information concerning the 

 anatomy and morphology of plants is likewise essential. With- 

 out knowledge of the structure of the plant, it is impossible to 

 comprehend the physiological processes taking place within it. 



Plant physiology is an independent science based on the 

 advance of other sciences, chiefly of physics and chemistry. It 

 likewise serves in its turn as a basis for agricultural sciences. 

 Success in agriculture depends on progress in physiology just 

 as success in physiology depends on progress in physics and 

 chemivStry. I have endeavored to hold in view this significance 

 of physiology for agriculture and have discussed with greater 

 detail all questions that are of special importance in their prac- 

 tical application. At the same time, I did not find it suitable 

 to emphasize questions that are discussed in courses in general 

 agriculture, agricultural chemistry, agricultural microbiology, 

 etc. For this reason, the subjects of assimilation of nitrogen by 

 microorganism.s, nitrification, fermentation, application of fertil- 

 izers, and the like are discussed very briefly in this volume, to 

 avoid unnecessary and harmful repetition. 



For the present fifth edition, I have thoroughly rewritten my 

 original textbook. In the preceding editions, I followed the 

 usual plan adopted in books on plant physiology of analyzing the 

 life of the plant according to its separate functions: assimila- 

 tion of carbon, nitrogen, and mineral elements; water relations; 

 metabolism; respiration and fermentation; growth and repro- 

 duction. Such an arrangement of the contents, which almost 

 excludes the possibility of considering the plant as a unit organ- 



