re

ee mr 6 ù De z Dep SE ge AE TT mi» k

16 ABSORBENT VESSELS.ll».

branch of a tree, torn from its trunk, and having one of its forks with the leaves on it inverted in a veflel of water, will continue for feveral days unwithered, nearly as well as if the whole had been placed upright in the water. A willow rod on the fame account will grow almoft equally well, whether the apex or bafe of it be fet in the ground; and Dr. Bradley, I think, mentions a young goofeberry-tree having been taken up, and replanted with its branches in the earth, and its roots in the air; and that the branches put forth root-fibres, and the roots put forth leaf-buds. There is likewife a curious expe- riment by Dr. Hales, who attached the eaftern branch of a young tree to its neighbour by inarching, and its weftern branch to another of its neighbours in the fame manner; and after they were united, he cut the ftem of the middle tree from its root, and thus left it hang- ing in the air by its two inarched arms, where it fourifhed with con- fiderable vigour.

This power of carrying their fluid contents in a retrograde direc- tion is alfo pofleffed in fome degree by the abforbents of animals, particularly in their difeafed ftate, and even in the operation of an emetic, as fhewn in Zoonomia, Vol. I, Se&. 29; and is vifible in the œfophagus or throat of cows, who convey their food firft down- wards, and afterward upwards by a direét and retrograde motion of the annular cartilages, which compefe the gullet, for the purpofe of rumination.;

7. The ftruture of thefe large vegetable abforbents, erroneoufly

<alled air-veflels, probably confifts of a fpiral line, and not of a veffel

interrupted with valves, and differs in this conftruétion from animal lymphatics; for firft, on breaking almoft any tender vegetable, as a Rft year’s fprig of a rofe-tree, or the middle rib of a vine-leaf, and gradually extending fome of the fibres, which adhere the longeft, this fpiral ftruéture becomes viñble even to the naked eye, and dif-

tm@ly fo by the ufe of à common lens, as is delineated in Duhamel’s

Phifique des arbres, T, 1. Tab, IL Fig. 17, 18, 19, and in Plate LI.

and