INTRODUCTION 



Plant physiology is the science that deals with the vital 

 phenomena of plants. Its purpose is to acquaint us with the 

 life of the plant and the processes occurring within it so as to 

 enable us to alter the course of these processes according to our 

 wishes and thus to control and govern the life of the plant and to 

 obtain from it the greatest possible amount of products necessary 

 for mankind. The utihzation of plants for human needs 

 being the chief problem of plant industry, a knowledge of the 

 physiology of plants naturally represents one of its essential 

 foundations. 



For a sufficiently exact and complete understanding of the 

 life of the plant, we must first of all reveal its inherent Hmita- 

 tions, study in detail the separate constituent processes, and 

 ascertain the importance of each of them in the development of 

 the plant as a living organism. Furthermore, it is essential to 

 analyze these processes fundamentally and to study the physical 

 and chemical phenomena on which they are based. Physiology, 

 however, cannot be restricted to this purely analytical problem. 

 Analysis must be followed by the solution of a problem of 

 synthetic character, viz., the reconstruction of the life of a plant 

 as a whole. This synthetic work should not be confined to a 

 study of the natural laws regulating plants in general and outside 

 of the influences of the natural environmental conditions. 

 Physiology must solve the more concrete problem of reproducing 

 the life picture of definite plants in environmental conditions 

 where they can successfully perform their vital functions. This 

 synthetic viewpoint leads, therefore, to the creation of a special 

 physiology, which from a practical point of view forms a very 

 important supplement to general plant physiology. 



Though a part of the botanical sciences, plant physiology is 

 also closely hnked with animal physiology. Life phenomena in 

 their fundamental aspects are similar in all living things. Many 

 of the essential organic functions, such as respiration, nutrition, 

 and irritability, are exhibited both by plants and by animals. 



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