CHEMISTRY OF VEGETATION.

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CHEMISTRY OF VEGETATION.

GENERAL VIEW

OF

THE CHEMICAL PHENOMENA

VEGETATION.

STRUCTURE OF PLANTS.

'Sf EGETABLES are organized bodies, which are nourished bycertain substances, received by and prepared within their ves-sels. They are all produced from seeds. They grow on theearth; at the bottom and on the surface of the ocean, and otherwaters; and parasitical upon other vegetables.

The structure of vegetables is nearly the same in all of them.They are composed of three principal parts, namely, the bark,the wood, and the pith. The lark is the outermost part: itcovers the whole body of the plant or tree. On examining itminutely, it will be found to be also composed of three distinctsubstances, called the epidermis, the parenchyma, and the corti-cal layers. The epidermis is a very thin transparent membranewhich covers the whole outer part of the bark. The parenchy-ma is placed below it: it is a succulent green membrane of a re-tiform texture. The cortical layers are the undermost: theyconsist of several thin membranes, composed of a multitude of Ion-