IZ 



ABSORBENT VESSELS. 



Sect. II. 3 



feen to bleed out haftily a milky juice, and at once evinced both the 

 abforbent and arterial fyftem. 



Many (imilar experiments were made by M, Bonnet, by placing 

 parts of the ftem or roots of various vegetables, as of kidney-beans, 

 peach-tree, and elder, in dilute ink ; in all thefe the vefTels of the bark 

 were uncoloured, and thofe of the pith ; but thofe beneath the bark, 

 which he terms woody, were coloured black, which I fuppofe to have 

 been the circle of abforbent veffels above mentioned. Ufage de Feu- 

 illes, Plate XXIX. 



3. Thefe abforbent veffels have been called bronchia by Malpighi 

 and Grew, and fome other philofophers, and erroneoufly thought to 

 be air- veffels ; in the fame manner as the arteries of the human body 



were fuppofed to convey air by the antients, till th 



Harvey 



by more exa£t experiments and jufter reafoning evinced, that they 

 were blood-veffels. This opinion has been fo far credited becaufe 



feen to iffue from wood, whether it be green or d 



T 



f 



be 



\ 



covered with water, and placed in the exhaufted receiver of an air- 

 pump ; and thefe veffels have therefore been fuppofed to conftitute 

 a vegetable refpiratory organ ; but it will be fliewn hereafter, that the 

 leaves of plants are their genuine lungs, and that the abforbent veffels 

 and arteries become accidentally filled with air in the dead parts of 

 vegetables. 



For as the veffels of vegetables are very minute, and have rigid 



their fides do not collapfe when they 



cut or brok 



as 



their juices flow out or exhale ; they mufl therefore receive air into 



them 



This may be readijy feen by infpedling with a common 



the end of a vinc-ftalk two or three years old 



h 



cut off h 



lly. At firft the veffels, which are feen between tjie partitions 



r 



radiated from the 



appear full of juice ; but in a minute or 



fs this juice either paffes on, or exhales; and the veffels appear empty, 



air. This experiment I have twenty times repeated 



filled with 



f 



with 



\ 



* 

 1 



r 



