XX INTRODUCTION 



Hence, numerous attempts have been made to create a science 

 of general physiology that should include the study of vital 

 activities manifested by all organisms. Such an approach to 

 the investigation of living beings, however, would leave out of 

 consideration the specific nature of plants. A deeper study of 

 the pecuharities of the life of plants requires, therefore, an 

 independent analysis of the problems that refer particularly 

 to their physiology. 



Though closely related to biological sciences of a descriptive 

 character, plant physiology differs, however, in that it is based 

 on physicochemical sciences. Thus in its analysis of vital 

 phenomena, in separating the reactions of complex processes, 

 plant physiology constantly resorts to physics and chemistry, and 

 its progress is closely connected with the growth of the physico- 

 chemical sciences. 



As has been stated previously, plant physiology forms one 

 of the most important foundations of the agricultural sciences. 

 Every important advance in plant physiology should lead, 

 therefore, to new success in the field of plant industry. Con- 

 versely, problems of agricultural character stimulate the study 

 of closely connected physiological problems, agriculturists fre- 

 quently participating in this investigation. Plant physiology 

 is certainly indebted in its advance to the work of agriculturists, 

 especially in problems of nutrition. The names of such agri- 

 cultural scientists as Boussingault, Hellriegel, and Prianishnikov 

 rank among the most famous in the history of plant physiology. 



Of all agricultural courses of study, agricultural chemistry is 

 the one that stands closest to plant physiology, so close that it is 

 impossible to draw a definite boundary between the two. The 

 problem of plant nutrition is closely connected with the problem 

 of fertilization; and it is quite natural therefore that technical 

 agriculturists are often obhged to solve problems of the physi- 

 ology of nutrition, while physiologists participate in the elabora- 

 tion of the problems of the application of fertilizers. 



Knowledge of plant physiology is also most essential in solving 

 problems of agronomy. Most of the agrotechnical methods 

 represent no more than an endeavor to create around the plant 

 favorable conditions that will ensure the highest possible jdeld. 

 Such are the various methods of tillage for the purpose of creating 

 a desirable soil structure or the different methods for the accumu- 



