086 PHILOSOPHICAL TRANSACTIONS. [anNO 1702. 



that bring part of the refluent blood from the lower parts of the body ; when 

 tliey consider the necessity of placing the human heart, as well as that of most 

 quadrupeds, so far from the centre of the body towards its upper part ? for that 

 end it is necessary that the large trunks of the veins and arteries should not 

 associate with each other; for if all the blood sent into the lower parts, by the 

 descending trunk of the aorta, should return again to the heart by one single 

 trunk, as it is sent out from thence, the weight of so much blood in the 

 ascending trunk of the vena cava would oppose the force the heart could give 

 it from the arteries, and hinder its ascent ; for this reason the vena azygos or 

 sine pari, is contrived to convey the blood sent to the muscles of the back and 

 thorax into the descending trunk of the vena cava above the heart ; hence it is 

 evident that more blood comes into the heart by the descending or upper trunk 

 of the vena cava, than passes out by the ascending trunks of the aorta. Nor 

 does this quantity of blood, conveyed to the heart by the superior trunk of the 

 cava, seem without some other design in nature, besides transporting it thither 

 to free the inferior trunk from its weight ; but perhaps it was necessary so much 

 blood should be ready there to join with the chyle, for its better mixture, before 

 it reaches the right auricle of the heart. 



The Explanation of the Figures. — PI. 17, fig. J, represents the trunks and 

 large branches of the arteries, dissected from an adult human body, when dis- 

 played and dried. Where, 1 is the trunk of the aorta cut from the basis of 

 the heart; 2 that part of it whence the coronary artery of the heart arises; 3 

 that part of the arteria magna, where the canalis arteriosus of the foetus termi- 

 nates, which in an adult becomes a ligament ; 44 that part of the^ixillary arteries, 

 by some called the subclavian arteries ; 5 the left carotid artery, which in this 

 subject seems to arise from a common trunk with the right carotid and axillary 

 arteries, as in some quadrupeds ; 6 the left cervical artery, in this subject arising 

 from the trunk of the arteria magna, as expressed in a figure given by Bergerus 

 in the Acta Eruditorum, An. 1698, p. 295 : but in all the human bodies in 

 which I have hitherto -examined these arteries, I have constantly found them as 

 expressed 6, 6, fig. 2 ; 7 the arteries that carry blood to the lower parts of the 

 face, tongue, adjacent muscles and glands ; 8 the trunk of the temporal artery, 

 springing from the carotid, and parting with branches to the parotid gland 9, 

 and temples 10, and parts adjacent; 11 the occipital arteries; 12 the arteries 

 that convey blood to the fauces, gargareon, and adjacent muscles ; 13 the trunk 

 of the carotid artery cut off, before it is contorted in passing the skull ; 14 the 

 trunk of the artery of the arm, parting with branches to the adjacent muscles 

 and parts : * that part of this artery which is sometimes pricked in letting blood, 

 and causes an aneurism ; in which case this trunk of the arterv must be bared 



