CHAPTER XVI 



PLANT PHYSIOLOGY 



156. Introductory. — Plants may be studied from several 

 points of view, each of which has resulted in a distinct 

 division of Botany. The study of the forms of plants and 

 their structure is Morphology, and it is this phase of Bot- 

 any which has been chiefly considered in the previous chap- 

 ters. The study of plants at w^ork is Physiology, and as 

 structure is simply preparation for work, the preceding 

 chapters have contained some Physiology, chiefly in refer- 

 ence to nutrition and reproduction. The study of the clas- 

 sification of plants is Taxonomy, and in the preceding 

 pages the larger groups have been outlined. The study of 

 plants as to their external relations is Ecology, a subject 

 which will be presented in the following chapter, and which 

 is the chief subject of Plant Relations. The study of the 

 diseases of plants and their remedies is Pathology ; their 

 study in relation to the interests of man is Economic 

 Botany. 



Besides these general subjects, which apply to all plants, 

 the ditt'erent groups form the subjects of special study. The 

 study of the Morphology, Physiology, or Taxonomy of the 

 Bacteria is Bacteriology ; of the Alg^e, Algology ; of the 

 Fungi, Mycology ; of the Bryophytes, Bryology ; of the 

 fossil plants, Palwohotany or Palwophytology, etc. 



In the present chapter it is the purpose to give a very 

 brief outline of tlie great subject of Plant Physiology, not 

 with the expectation of presenting its facts adequately, but 

 with the hope that the important field thus presented may 



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