BOTANY. 



CHAPTER I. 



INTRODUCTION. 



ALL matter is composed of certain constituents (about sev- 

 enty are at present known), which, so far as the chemist is 

 concerned, are indivisible, and are known as elements. 



Of the innumerable combinations of these elements, two 

 general classes may be recognized, organic and inorganic bodies. 

 While it is impossible, owing to the dependence of all organ- 

 ized matter upon inorganic matter, to give an absolute defini- 

 tion, we at once recognize the peculiarities of organic or living 

 bodies as distinguished from inorganic or non-living ones. All 

 living bodies feed, grow, and reproduce, these acts being the 

 result of the action of forces resident within the organism. 

 Inorganic bodies, on the other hand, remain, as a rule, un- 

 changed so long as they are not acted upon by external forces. 



All living organisms are dependent for existence upon inor- 

 ganic matter, and sooner or later return these elements to the 

 sources whence they came. Thus, a plant extracts from the 

 earth and air certain inorganic compounds which are converted 

 by the activity of the plant into a part of its own substance, 

 becoming thus incorporated into a living organism. After the 

 plant dies, however, it undergoes decomposition, and the ele- 

 ments are returned again to the earth and atmosphere from 

 which they were taken. 



Investigation has shown that living bodies contain compara- 

 tively few elements, but these are combined into extraordina- 



1 



