\ 



5 



8 



AORTAL ARTERIES 



Sect. V. r. 



foot-ftalks of the leaves, anci expofe it on the upper furface of them 

 to the influence of the air through a thin moifl pellicle, where it 

 changes its colour, and returns by correfpondent veins like the blood 



of animals. 



The aortal arteries of the more perfeft animals receive the blood 

 from the left cavity of the heart, after it has been expofed to the 

 influence of the air in the lungs, and difperfe it by numerous rami- 

 fications over the v^hole body for the purpofes of fecretion and nu- 

 trition. In lefs perfect animals the aorta itfelf has a pulfation, and 

 carries forward the blood without the affiftance of a heart, as may be 

 feen in the back of a full-grown filk-worm by the naked eye, and 

 very diftinflly by the ufe of a common lens. After the blood has 

 paffed the various glands and capillaries, it is received by another {yr- 

 tem of veflels, the veins, which conflitute a kind of refervoir for the 



1 



quantity of blood', that remains unexpended by the fecretions, ex- 

 cretions, nutrition, and growth of the animal ; by thefe it is again 

 carried to the right cavity of the heart, and again expofed in the 

 lungs to the influence of the air. 



In a fimilar manner the branchino; veins, which bring: the bjood 



& 



from the leaves of plants, after it has been expofed to the influence 

 of the air, unite at the foot-ftalk of each leaf into more or fewer 

 trunks, as may be feen in tearing off the foot-flalk of a leaf of a 

 chefnut-tree from the ftem ; and there without the interpofition of a 



h 



ke the circulation in the aorta of fifh 



d that in th 



of red-blooded animals, thefe venous trunks take the office of arte- 



ries, and difperfe the blood downwards along the bark to the roots, 

 and to every other part of the vegetable fyflem, performing the va- 

 rious purpofes of fecretion, excretion, and nutrition, as was (hewn 



in 



th 



e experiment 



of placing a fig-leaf in 



a deco(5tion of madder 



defcribed in Se6l. IV. i . 3. of this work. 



But as vegetables drink up their adapted nourifliment perpetually 

 (rora the moifl earth, and in confequence muft be fuppofed to take 



