7 Ps

SEcr.1l:2, ABSORPBENF VESSELS. II

Beñdesthefe abforbents in the roots of plants there are others, which open their mouths on the external furfaces of the bark and leaves to abforb the moifture of the atmofphere, refembling the cutaneous lymphatics of animal bodies; the exiftence of thefe is fhewn, becaufe a leaf plucked off and laid with its under fide on water will not wither fo foon as if left in the dry air. The fame if the bark alone of à branch, which is feparated from a tree, be kept moift with water.

A third branch of abforbent veflels opens its mouths on the internal furfaces of the cells and cavities of the vegetable fyftem to abforb the {ecreted fluids, after they have performed their adapted offices, fimilar to the cellular lymphatics. of animal bodies, as may be fhewn by moiftening the alburnum or fap-wood, and the internal furface of the bark of a branch detached from a tree, which will not then fo foon wither as if left in the dry air unmoiftened,

Another means of demonftrating the abforbent powers of the parts of vegetables is by inferting them into glafs tubes, or into tall narrow veflels filled with water, and obferving how much more rapidly the {urface of the water fubfides than in fimilar veflels by evaporation alone.

2. By the following experiment thefe vegetable abforbent veflels were made agreeably vifible by a common magnifying glafs. I placed in the fummer of 1781 fome twigs of a fig-tree with leaves on them about an inch deep in a decoétion of madder(Rubia tiné), and others in a.-decoction of logwood(hæmatoxylum campechenfe), along with fome fpriss cut off from a plant of picris. Thefe plants were chofen becaufe their blood is white. After fome hours, and on the next day, on taking out either of thefe, and cutting off from its bottom about an eighth of an inch of the ftalk, an internal circle of red points appeared, which I believed to be the ends of abforbent veflels coloured red with the decoction, and which probably exifted in the newly formed alburnum, or fap-wood, while an external ring of arteries was

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