CHAPTER XXIV. 



BOTANY GENERAL AND STRUCTURAL. 



THE science of Botany includes everything relating to the 

 vegetable kingdom. It considers the external forms of plants, 

 their anatomical structure, however minute, their classification, 

 geographic distribution, and economic value. It treats of the 

 varied relations of plants among themselves, and of their rela- 

 tions to minerals on the one side, and to animals on the other. 

 It attempts to examine plants in their earliest form, as single 

 cells, and to follow them through all their stages of development 

 until they reach maturity; in short, endeavors to learn the life 

 history of plants. 



Many plants are minute in size, and much of the structure of 

 all plants is microscopic, so that there is considerable botanical 

 work which can be done only in well equipped laboratories, with 

 microscopes, re-agents, and mechanical appliances beyond the 

 reach of most individuals; but wide and interesting fields, the 

 greater part of botany, lie easily within the range of the unaided 

 vision. A good pocket magnifying glass will, however, be found 

 useful in the study of plants, animals or minerals. 



Plants are composed of carbon, hydrogen, oxygen, nitrogen, 

 sulphur, iron and potassium as essential elements, necessary to 

 their life and growth, and sometimes they contain phosphorus, 

 calcium, sodium, silicon, magnesium or chlorine, as elements of 

 secondary importance in the vegetable structure. While the plant 

 is made up of the elements mentioned, it cannot feed on them as 

 elements, they must be united into compounds as water, carbon 

 dioxide, ammonium nitrate, calcium phosphate, etc., before the 

 plant can utilize them for food. Oxygen seems to be the only 

 exception to this rule, being an elemental plant food. 



The living portion of the plant, that which moves, appropri- 

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