4 



68 



AORTAL ARTERIES 



Sect..V. &, 



-e 



and forms a large trunk, which pafles up the alburnuffi of the tree ta 

 the upper caudex of the bud at the foot-flalk of the leaf,, and may 

 be compared to the receptaculum chyh of animals extended to fo 

 great a length ; and that it there joins the great returning vein, which 

 alfo is compofed of the branching veins of the roots uniting at the 

 lower caudex of the bud, and afeending terminates at the upper 

 caudex of it, where it becomes again branched, and forms the pul- 

 mionary artery. 



The aorta or great artery defcends, I fuppofe, along with the great 

 vein, or vena cava above mentioned ; and branching in the roots be- 



and on all other parts of the individual leaf-bud, performs the 



low, ar 



offices of fecretion and 



The pulmonary arteries and 



belong to the leaf; the former expofes the blood to th 



beneath a thin moift pell 



atmofph 

 hence it becomes oxygenated, and pro 



A 



bably acquires fome warmth, and phofphoric acid, and the fpirit of 

 vegetable life. The latter eolleds the aerated blood by its branches, 

 and conveys it to the upper caudex of the bud, at the foot-llalk of the 

 leaf, where it becomes the aorta or great artery above mentioned. 



Th 



fides of the long abforbent trunk 



ptacles of chyl 



i 



which rife from the lower caudex and terminate in the upper caudex 

 of each bud, as well as the long trunks of the umbilical veffels de- 

 fcribed in Se^:. HI. evidently confift of a fpiral line, as well as thofe 

 trunks of abforbents, which imbibe aqueous fluids from the air, and 

 a part of their perfpirable matter on the furfaces of the leaves. But 

 whether the pulmonary and aortal arteries*or great Veins confift of a 

 fimilar ftrudure is not yet afcertained. 



I (hall here relate the following experiments, which were made a 



i^^ days 

 Some 



firm or confute the ideas above delivered 



ftems of large fp 



phorbia, were fet upright in a d 



co£lion of oak-galls, and others in a folution of 



c> 



Gnth 



as 



day thefe were reciprocally removed from the one to the other, 



this management I fuppofed that the black molecules would 



r 



be 



ft . 



