1 68 Circulation of the Blood 



parable to a hot kettle, not because of its proper 

 substance, but because of its contained blood ; for the 

 same reason, because they have numerous veins or 

 vessels containing blood, are the liver, spleen, lungs, 

 c., reputed hot parts. And in this way do I view the 

 native or innate heat as the common instrument of 

 every function, the prime cause of the pulse among the 

 rest. This, however, I do not mean to state absolutely, 

 but only propose it by way of thesis. Whatever may 

 be objected to it by good and learned men, without 

 abusive or contemptuous language, I shall be ready to 

 listen to I shall even be most grateful to any one who 

 will take up and discuss the subject. 



These, then, are, as it were, the very elements and 

 indications of the passage and circulation of the blood, 

 viz. from the right auricle into the right ventricle ; from 

 the right ventricle by the way of the lungs into the left 

 auricle ; thence into the left ventricle and aorta ; whence 

 by the arteries at large through the pores or interstices 

 of the tissues into the veins, and by the veins back 

 again with great rapidity to the base of the heart. 



There is an experiment on the veins by which any 

 one that chooses may convince himself of this truth : 

 Let the arm be bound with a moderately tight bandage, 

 and then, by opening and shutting the hand, make all 

 the veins to swell as much as possible, and the integu- 

 ments below the fillets to become red ; and now let the 

 arm and hand be plunged into very cold water, or snow, 

 until the blood pent up in the veins shall have become 

 cooled down ; then let the fillet be undone suddenly, 

 and you will perceive, by the cold blood returning to 

 the heart, with what celerity the current flows, and what 

 an effect it produces when it has reached the heart ; so 

 that you will no longer be surprised that some should 

 faint when the fillet is undone after venesection. 1 This 

 experiment shows that the veins swell below the 

 ligature not with attenuated blood, or with blood raised 



1 Vide Chapter XI, of the Motion of the Heart, &c. 



