OP THE ARTERIES. 275 



much probability, to have a very great influence upon the per- 

 fecting of the lymph and chyle, and on the formation of the 

 blood. 





SECTION II. 



OP THE ARTERIES. 



405. The arteries,* qrteriae, are the vessels which convey 

 the blood from the heart to all the parts of the body. 



406. Hippocrates and his contemporaries gave the name 

 of veins to all the vessels and canals, with the exception of 

 the trachea, which they called artery. Aristotle is the first 

 who speaks of the aorta, which he names the small vein. 

 Praxagoras gives the name of artery to the aorta and its 

 branches, which he believed to contain a vapour. The school 

 of Alexandria distinguishes the arteries from the veins by the 

 thickness of the walls, and admits that the blood may, under 

 certain circumstances, pass into the arteries. Galen, the 

 greatest anatomist of antiquity, tries to prove that the arteries 

 are full of blood in their natural state. He considers the ve- 

 nous system and the arterial system each a tree, whose roots, 

 implanted in the lungs, and whose branches, distributed 

 throughout the body, meet at the heart. It was not until Ve- 

 salius, that the first rudiments of the art of injecting the blood 

 vessels were known, and it was not until his day that some 

 notions respecting the texture of the blood vessels are to be 

 found. Their functions and alterations have only been known 

 in later times. 



407. There are two arterial trunks; the aorta and the pul- 

 monary artery, both have an arborescent disposition, and pre- 



* BassueJ, nouvel aspect de Pinterieur des arteres, et de leur structure par 

 rapport au cours du sang; mm. pretcnt. de math, et de phys. torn. I. ann. 

 1750. D. Belmas, structure des arteres, leurs proprittts, kurs functions et 

 kurs alterations organiques. in 4to. Strasbourg, 1822. Ch. H. Ehrmann, 

 the same title, place and date. 



