LESSON l.J BOTANY, WHAT IT RELATES TO. 3 



earth and air, upon which animals cannot subsist at all, and to con- 

 vert these into something upon which animals can subsist, that is, 

 into food. All food is produced by plants. How this is done, it is 

 the province of Vegetable Physiology to explain. 



8. Botany is the name of the science of the vegetable kingdom in 

 general. 



9. Physiology is the study of the way a living being lives, and 

 grows, and performs its various operations. The study of plants in 

 this view is the province of Vegetable Physiology. The study of the 

 form and structure of the organs or parts of the vegetable, by which 

 its operations are performed, is the province of Structural Botany. 

 The two together constitute Physiological Botany. With this de- 

 partment the study of Botany should begin ; both because it lies 

 at the foundation of all the rest, and because it gives that kind of 

 knowledge of plants which it is desirable every one should possess ; 

 that is, some knowledge of the way in which plants live, grow, and 

 fulfil the purposes of their cKistence. To this subject, accordingly, 

 a large portion of the following Lessons is devoted. 



10. The study of plants as to their kinds is the province oi Sys- 

 tematic Botany. An enumeration of the kinds of vegetables, as far 

 as known, classified according to their various degrees of resemblance 

 ■or diflFerence, constitutes a general System of plants. A similar ac- 

 count of the vegetables of any particular country or district is called 

 a Flora of that country or district. 



11. Other departments of Botany come to view when — instead 

 of regarding plants as to what they are in themselves, or as to their 

 relationship with each other — we consider them in their relations 

 to other things. Their relation to the earth, for instance, as respects 

 their distribution over its surface, gives rise to Geographical Botany, 

 or Botanical Geography. The study of the vegetation of former 

 times, in their fossil remains entombed in the crust of the earth, 

 gives rise to Fossil Botany. The study of plants in respect to their 

 uses to man is the province of Agricultural Botany, Medical Botany, 

 and the like. 



