CHAPTER XV 



PLANTS 



305. Plants and the Soil. The close connection be- 

 tween plants and the soil has already been spoken of 

 (cf. 298). Plants take out of the soil and the air about 13 

 elements; out of these elements the higher plants build 

 up complicated and beautiful structures, known as roots, 

 stems, leaves, flowers, and seeds. We call these struc- 

 tures the organs of the plant (cf. 3). How is it that 

 plants are able to bring about this wonderful change of 

 the materials of soil and air into living plant material, or 

 plant "tissue?" For the answer, in so far as men know it, 

 we shall need to go to textbooks of Botany. It is enough 

 to say that plants are living organisms, and that if we 

 put the embryo plant, that is, the plant which is enclosed 

 in the seed, into fertile soil, and leave it exposed to the 

 sunshine, the air, and the rain, it will sprout and grow. 

 Sooner or later it will become a full-grown plant, like its 

 parent, and will be able to carry on all the processes of 

 which its parent was capable. 



306. Functions of Plants. When we enumerate the 

 organs of the higher plants, as we did in the preceding 

 section, we at once think of some special function, or duty, 

 which each performs for the plant. We can classify all 

 these special functions as parts of two general functions, 

 which all plants must carry out; for life depends upon 



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