138 CIRCULATION OF THE BLOOD. 



and stimulation ; so that the warmer any part is, the greater 

 is its supply of blood, or otherwise; where the blood is in 

 largest quantity, there also is the heat highest. For this reason 

 is the heart, remarkable through its cavities, to be viewed as the 

 elaboratory, fountain, and perennial focus of heat, and as compa- 

 rable 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 pro- 

 pose it by way of thesis. Whatever may be objected to it by 

 good and learned men, without abusive or contemptuous lan- 

 guage, 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 indica- 

 tions 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 integuments below the fillet 

 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 re- 

 turning 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 attenu- 

 ated blood, or with blood raised by spirits or vapours, for the 



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



