114 WILLIAM HARVEY 



But if anyone shall here object that a large quantity 

 may pass through and yet no necessity be found for a 

 circulation, that all may come from the meat and drink 

 consumed, and quote as an illustration the abundant supply 

 of milk in the mammae for a cow will give three, four, 

 and even seven gallons and more in a day, and a woman 

 two or three pints whilst nursing a child or twins, which 

 must manifestly be derived from the food consumed; it 

 may be answered that the heart by computation does as 

 much and more in the course of an hour or two. 



And if not yet convinced, he shall still insist that when 

 an artery is divided, a preternatural route is, as it were, 

 opened, and that so the blood escapes in torrents, but that 

 the same thing does not happen in the healthy and un- 

 injured body when no outlet is made; and that in ar- 

 teries filled, or in their natural state, so large a quantity 

 of blood cannot pass in so short a space of time as to 

 make any return necessary to all this it may be answered 

 that, from the calculation already made, and the rea- 

 sons assigned, it appears that by so much as the heart in 

 its dilated state contains, in addition to its contents 

 in the state of constriction, so much in a general way 

 must it emit upon each pulsation, and in such quantity 

 must the blood pass, the body being entire and naturally 

 constituted. 



But in serpents, and several fishes, by tying the veins 

 some way below the heart you will perceive a space be- 

 tween the ligature and the heart speedily to become empty; 

 so that, unless you would deny the evidence of your senses, 

 you must needs admit the return of the blood to the heart. 

 The same thing will also plainly appear when we come 

 to discuss our second position. 



Let us here conclude with a single example, confirming 

 all that has been said, and from which everyone may ob- 

 tain conviction through the testimony of his own eyes. 



If a live snake be laid open, the heart will be seen 

 pulsating quietly, distinctly, for more than an hour, mov- 

 ing like a worm, contracting in its longitudinal dimensions, 

 (for it is of an oblong shape), and propelling its con- 

 tents. It becomes of a paler colour in the systole, of a 



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