PRINCIPLES OF PLANT 

 PHYSIOLOGY 



CHAPTER I 



PLACE OF PLANT PHYSIOLOGY; CLASSIFICATION 

 OF THE BOTANICAL SCIENCES 



The world is so full of a number of things, 

 I'm sure we should all be as happy as kings. 



— Stevenson. 



The Sciences. — Owing to the multiplicity of facts in the world, 

 man has found it convenient to classify and arrange those he 

 knows into certain groups. Thus have arisen the various fields 

 of knowledge such as history, botany, music, etc. In common 

 speech those organized bodies of fact like astronomy and geology 

 which deal with material things in the realm of nature are called 

 sciences, while those such as music, history, and logic which deal 

 with ideas, emotions, and feelings are not ordinarily so called. The 

 ancients, however, called all these organized groups of facts 

 " sciences" and, for our purpose in this chapter, we shall so con- 

 sider them. 



There are then three great associations of sciences, — the physical, 

 the biological, and the psychological. The physical sciences are 

 concerned with nonliving matter and include physics, chemistry, 

 meteorology, etc. The biological sciences include botany and 

 zoology, — the sciences of living things; while the psychological 

 sciences include psychology, and, in a philosophical sense, logic 

 and mathematics. 



The most casual observer, however, will not fail to see that 

 even the best classification cannot be "cut and dried" and can- 

 not separate the fields of knowledge into "water-tight compart- 

 ments." If we place physics at the red end of a knowledge spec- 

 trum, biology in the middle in the green portion, and psychology 

 in the violet end, we shall thus have a series of fields of knowledge 

 which, like the wave lengths we have used to represent them, 



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