CIRCULATION OF THE BLOOD 111 



with each stroke two drachms are expelled, the quantity 

 would, of course, amount to twenty pounds and ten ounces; 

 if half an ounce, the quantity would come to forty-one 

 pounds and eight ounces; and were there one ounce, it 

 would be as much as eighty-three pounds and four ounces; 

 the whole of which, in the course of one-half hour, would 

 have been transfused from the veins to the arteries. The 

 actual quantity of blood expelled at each stroke of the 

 heart, and the circumstances under which it is either greater 

 or less than ordinary, I leave for particular determination 

 afterwards, from numerous observations which I have made 

 on the subject. 



Meantime this much I know, and would here proclaim 

 to all, that the blood is transfused at one time in larger, 

 at another in smaller, quantity; and that the circuit of 

 the blood is accomplished now more rapidly, now more 

 slowly, according to the temperament, age, etc., of the 

 individual, to external and internal circumstances, to natu- 

 rals and non-naturals sleep, rest, food, exercise, affec- 

 tions of the mind, and the like. But, supposing even the 

 smallest quantity of blood to be passed through the heart 

 and the lungs with each pulsation, a vastly greater amount 

 would still be thrown into the arteries and whole body 

 than could by any possibility be supplied by the food 

 consumed. It could be furnished in no other way than by 

 making a circuit and returning. 



This truth, indeed, presents itself obviously before us 

 when we consider what happens in the dissection of living 

 animals; the great artery need not be divided, but a very 

 small branch only (as Galen even proves in regard to 

 man), to have the whole of the blood in the body, as 

 well that of the veins as of the arteries, drained away 

 in the course of no long time some half-hour or less. 

 Butchers are well aware of the fact and can bear witness 

 to it; for, cutting the throat of an ox and so dividing 

 the vessels of the neck, in less than a quarter of an hour 

 they have all the vessels bloodless the whole mass of 

 blood has escaped. The same thing also occasionally oc- 

 curs with great rapidity in performing amputations and re- 

 moving tumors in the human subject. 



