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BOOK III. 



PHYSIOLOGY OE ORGANOLOGY. 



Having now described plants in reference to their structure, 

 classification, properties, and uses, we have, in the last place, 

 briefly to consider them in a state of life or action, — that is, to 

 explain, as far as science enables us, the laws which regulate 

 their life, growth, and reproduction. The department of botany 

 which investigates these phenomena is termed Physiology or 

 Organology ; and the various processes which the plant per- 

 forms, and which are the necessary accompaniments of its life, 

 are called its functions. The different functions thus concerned 

 in the life of the plant, are naturally divided into two classes, 

 called, respectively, the functions of the organs of vegetation, 

 and the functions of the organs of reproduction ; the former 

 being those concerned in preserving the life of any particular 

 plant, and the latter in continuing the species. Physiology in- 

 cludes the study of the life of the whole plant, when it is termed 

 general ; and that of the particular organs, in which case it is 

 called special. 



In the present unsatisfactory state of our knowledge of many 

 points connected with the physiology of plants, we have much 

 difficulty in arranging a good plan for its study. In treating, 

 therefore, of the functions of the diflferent organs, I shall follow, 

 as far as possible, the order of arrangement adopted in treating 

 of their structure and morphology, and conclude with a few 

 observations on some special phenomena in the life of the plant. 



