Catalogue of Works on Gardening, <$c. 375 



" In the ripening of fruits a different series of changes presents itself. 

 The fruit is first tasteless, then becomes sour, and at last sweet. In this 

 case the acid of the unripe is changed into the sugar of the ripened fruit. 



" The substance of plants, — their solid parts that is — consist chiefly of 

 woody fibre, the name given to the fibrous substance, of which wood evidently 

 consists. It is interesting to enquire how this substance can be formed from 

 the compounds, carbonic acid and water, of which the food of plants in great 

 measure consists. Nor is it difficult to find an answer. 



" It will be recollected that the leaf drinks in carbonic acid from the air, 

 and delivers back its oxygen, retaining only its carbon. It is also known 

 that water abounds in the sap. Hence carbon and water are thus abundantly 

 present in the pores or vessels of the green leaf. Now, woody fibre consists 

 only of carbon and water chemically combined together; 100 1b. of dry 

 woody fibre consisting of 50 lb. of carbon and 50 lb. of water. It is easy, 

 therefore, to see how, when the carbon and water meet in the leaf, woody 

 fibre may be produced by their mutual combination. 



" If, again, we enquire how this important principle of plants may be formed 

 from the other substances, which enter by their roots, from the ulmic acid, 

 for example, the answer is equally ready. This acid also consists of carbon 

 and water only, 50 lb. of carbon with 37| lb. of water forming ulmic acid ; so 

 that when it is introduced into the sap of the plant, all the materials are 

 present from which the woody fibre may be produced. 



" Nor is it more difficult to see how starch may be converted into sugar, 

 and this again into woody fibre; or how, again, sugar may be converted into 

 starch in the ear of corn, or woody fibre into sugar during the ripening of the 

 winter pear after its removal from the tree. Any one of these substances may 

 be represented by carbon and water only. Thus : — 



50 lb. of carbon with 50 of water, make 100 of woody fibre. 

 501b. - - 37i - - 87a of ulmic acid. 



501b - - 721 . . 122^ -f of cane sugar, of starch, 



2 2 L or °f gum- 



SO lb. 56 - - 106 of vinegar. 



In the interior of the plant, therefore, it is obvious that, whichever of these 

 substances be present in the sap, the elements are at hand out of which any 

 of the others may be produced. In what way they really are produced, the 

 one from the other, and by what circumstances these transformations are 

 favoured, it would lead into too great detail to attempt here to explain. (For 

 fuller and more precise explanations on these interesting topics, see the 

 Author's Lectures on Agricultural Chemistry and Geology, Part I.) 



" We cannot help admiring to what varied purposes in nature the same 

 elements are applied, and from how few and simple materials substances the 

 most varied in their properties are, in the living vegetable, daily produced." 



The ash of plants consists of a mixture of several earthy substances, some- 

 times as many as the eleven following : — Potash, soda, lime, magnesia, silica, 

 alumina, oxide of iron, oxide of manganese, sulphur, phosphorus, and chlorine. 

 The quantity and quality of the ash of plants is, as might be expected, very 

 different. In the grain of wheat and oats, all the eleven substances are found, 

 except the oxide of manganese ; but in the straw of wheat the oxide of 

 iron also is wanting ; and in oat straw there is no soda, alumina, oxide of 

 iron, of manganese, nor chlorine. The kind of organic matter varies with the 

 part of the plant, and one inorganic ingredient may be abundant in the seed, 

 and scarcely to be found in the leaves and stems. Thus, the grain of wheat 

 contains 20| per cent of soda, while the straw contains only £ per cent. 

 Hence the leaves and stalks of a plant, without its seeds, will not constitute 

 a sufficient manure for that plant, because it does not supply all the inorganic 

 ingredients that have been carried off by it. 



But we have said enough to give an idea of this very excellent work, which 

 we most strongly recommend to the young cultivator who is desirous of 

 acquiring one of the most important parts of the science of his art. 



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