152 Proceedings of the Ohio State Academy of Science 



inonary circulation. He arrives at this conclusion from his 

 estimate of the amount of blood in the body, and that arteries 

 would become congested if there w-as no way for it to get (jut 

 of the arteries; the body could not use up the blood as fast as 

 it was made or absorbed from the viscera, therefore the blood 

 must travel in a circle from the left side of the heart through 

 die arteries of the tissues from the tissues to the vein? 

 through them to the right side of tlie heart, through the pul- 

 monary artery to the lungs, through the pulmonary vein tc 

 the left side of the heart. In other words the blood must 

 travel in a circle, lie says: "I frequently and seriously be- 

 thought me, and long revolved in my mind, what might be 

 the quantity of blood which was transmitted, in how short a 

 time its passage miglit be affected, and the like; and not lind- 

 ing" it possible that this could be supplied by the juices of the 

 ingested aliment with.out the veins on the one hand becoming 

 drained, and the arteries on the other hand becoming ru])- 

 tured through the excessive charge of Idood, unless the l^lood 

 should somehow find its way from the arteries into the veins, 

 and so retium to the right side of the heart; I began to think 

 whether there might be a motion, as it were, in a circle. Now 

 this I afterwards found to be true; and I finally saw^ that the 

 blood, forced by the action of the left ventricle into the ar- 

 teries, was distributed to the body at large, and its several 

 ])arts, in the same manner as it is sent through the lungs, 

 impelled by the right ventricle into the pulmonary artery and 

 that it then passed through the veins and along the vena cava 

 and so round to the left ventricle in the manner already in- 

 dicated, which motion we may be allowed to call circular." 



The heart is emptied when the vena cava is tied, the vena 

 cava becomes distended v/hen the aorta is tied, the limb be- 

 comes swollen wdien a tight ligature is supplied to shut off' 

 the veins, the same limb becomes pale when a tight ligature 

 is applied to shut off the arteries, nearly all of the blood in 

 the body can be drained away from a single opening in a 

 vein. All of this can be easily understood in the light of 



