Page:An introduction to physiological and systematical botany (1st edition).djvu/99

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OF THE SECRETED FLUIDS OF PLANTS GRAFTING. HEAT OF THE VEGETABLE BODY.

sap in its passage through the leaves and bark becomes quite a new fluid, possessing the peculiar flavour and qualities of the plant, and not only yielding woody matter for the increase of the vegetable body, but furnishing various secreted substances, more or less numerous and different among themselves. These accordingly are chiefly found in the bark; and the vessels containing them often prove upon dissection very large and conspicuous, as the turpentine-cells of the Fir tribe. In herbaceous plants, whose stems are only of annual duration, the perennial roots frequently contain these fluids in the most perfect state, nor are they, in such,