6 INTRODUCTION. 



When we have become acquainted with the internal and 

 external structure of the plant, we see how it rejoices in an 

 untiring power of development, ever calling forth new 

 plants in inexhaustible abundance, careful that no bare 

 spot shall show itself in the rich and variegated carpet with 

 which nature clothes the naked earth. The development 

 of the form and organs of the plant, the calling forth and 

 the production of numerous descendants, requires material. 

 It must come into existence, maintain itself and multiply, 

 and thus we are led to the Nutrition of plants. At this 

 point, more particularly, we are compelled to observe the 

 relations of the plant to its supporter, the earth, and to 

 its destroyer, man. The whole animal world, and, above 

 all, mankind, asserts its claim upon the vegetable world ; 

 this must furnish sustenance to a countless poor, since it 

 subsists and grows subject to the destination that the 

 matter applied to its own development shall, moreover, 

 serve for the food or uses of the other earthly organisms. 

 This nutrition of plants, however, may be looked at in two 

 ways, for, to express it briefly, if we burn a plant, a 

 portion only is destroyed, which combustible part we call 

 the organic matter of the plant, and this claims our especial 

 interest (vi), because it includes the main substance of the 

 nutriment cf the animal world. But a varying proportion 

 of the plant remains behind, as ash, after the burning; 

 and this also, which we call inorganic matter, invites our 

 attention (vn), so much the more, indeed, when we find 

 that this ash, improbable as it may at first appear, likewise 

 plays no unessential part in the nutrition of animals and 

 man. In both ways of looking at the subject, we are 

 reminded that man, where advanced civilization has 

 crowded him more closely upon small areas, is and can be 

 no longer content with what mother-earth freely brings 



