62 Motion of the 



performing amputations, the blood escaped in equal, 

 if not perchance in larger quantity by the veins than by 

 the arteries. The contrary of this statement, indeed, 

 is certainly the truth ; the veins, in fact, collapsing, 

 and being without any propelling power, and further, 

 because of the impediment of the valves, as I shall 

 show immediately, pour out but very little blood ; whilst 

 the arteries spout it forth with force abundantly, 

 impetuously, and as if it were propelled by a syringe. 

 And then the experiment is easily tried of leaving the 

 vein untouched, and only dividing the artery in the 

 neck of a sheep or dog, when it will be seen with what 

 force, in what abundance, and how quickly, the whole 

 blood in the body, of the veins as well as of the 

 -arteries, is emptied. But the arteries receive blood 

 from the veins in no other way than by transmission 

 through the heart, as we have already seen ; so that if 

 the aorta be tied at the base of the heart, and the 

 carotid or any other artery be opened, no one will now 

 be surprised to find it empty, and the veins only replete 

 -with blood. 



And now the cause is manifest, wherefore in our 

 dissections we usually find so large a quantity of blood 

 in the veins, so little in the arteries ; wherefore there is 

 anuch in the right ventricle, little in the left ; circum- 

 stances which probably led the ancients to believe 

 that the arteries (as their name implies) contained 

 nothing but spirits during the life of an animal. The 

 true cause of the difference is this perhaps : that as 

 there is no passage to the arteries, save through the 

 lungs and heart, when an animal has ceased to breathe 

 and the lungs to move, the blood in the pulmonary 

 artery is prevented from passing into the pulmonary 

 veins, and from thence into the left ventricle of the 

 heart ; just as we have already seen the same transit 

 prevented in the embryo, by the want of movement in 

 the lungs and the alternate opening and shutting of 

 their minute orifices and invisible pores. But the 



