154 Circulation of the Blood 



of the vein and coming down from the head, a round 

 torrent of blood gushed forth. You may observe the 

 same fact any day in practising phlebotomy : if with 

 a finger you compress the vein a little below the orifice, 

 the flow of blood is immediately arrested ; but the 

 pressure being removed, forthwith the flow returns 

 as before. 



From any long vein of the forearm get rid of the 

 blood as much as possible by holding the hand aloft 

 and pressing the blood towards the trunk, you will 

 perceive the vein collapsed and leaving, as it were, in 

 a furrow of the skin ; but now compress the vein with 

 the point of a finger, and you will immediately perceive 

 all that part of it which is towards the hand, to enlarge 

 and to become distended with the blood that is coming 

 from the hand. How comes it when the breath is held 

 and the lungs thereby compressed, a large quantity of 

 air having been taken in, that the vessels of the chest 

 are at the same time obstructed, the blood driven into 

 the face, and the eyes rendered red and suffused ? 

 Why is it, as Aristotle asks in his problems, that all 

 the actions are more energetically performed when the 

 breath is held than when it is given ? In like manner, 

 when the frontal and lingual veins are incised, the blood 

 is made to flow more freely by compressing the neck 

 and holding the breath. I have several times opened 

 the breast and pericardium of a man within two hours 

 after his execution by hanging, and before the colour 

 had totally left the face, and in presence of many 

 witnesses, have demonstrated the right auricle of the 

 heart and lungs distended with blood ; the auricle 

 in particular of the size of a large man's fist, and so full 

 of blood that it looked as if it would burst. This great 

 distension, however, had disappeared next day, the 

 body having stiffened and become cold, and the blood 

 having made its escape through various channels. 

 These and other similar facts, therefore, make it 

 sufficiently certain that the blood flows through the 



