112 CIRCULATION OF THE BLOOD. 



feel the blood coming down in the artery at each pulsation, and 

 visibly dilating the vessel. You may also at will suffer the 

 blood to escape, by relaxing the pressure, and leaving a small 

 outlet ; and you will see that it jets out with each stroke, with 

 each contraction of the heart, and with each dilatation of the 

 artery, as I have said in speaking of arteriotomy, and the ex- 

 periment of perforating the heart. And if you suffer the efflux 

 to go on uninterruptedly, either from the simple divided artery 

 or from a tube inserted into it, you will be able to perceive 

 by the sight, and if you apply your hand, by the touch likewise, 

 every character of the stroke of the heart in the jet ; the rhythm, 

 order, intermission, force, &c., of its pulsations, all becoming 

 sensible there, no otherwise than would the jets from a syringe, 

 pushed in succession and with different degrees of force, received 

 upon the palm of the hand, be obvious to sight and touch. I 

 have occasionally observed the jet from a divided carotid artery 

 to be so forcible, that, when received on the hand, the blood 

 rebounded to the distance of four or five feet. 



But that the question under discussion, viz. that the pul- 

 sific power does not proceed from the heart by the coats of the 

 vessels, may be set in yet a clearer light^ I beg here to refer to 

 a portion of the descending aorta, about a span in length, with 

 its division into the two crural trunks, which I removed from 

 the body of a nobleman, and which is converted into a bony 

 tube ; by this hollow tube, nevertheless, did the arterial blood 

 reach the lower extremities of this nobleman during his life, 

 and cause the arteries in these to beat ', and yet the main trunk 

 was precisely in the same condition as is the artery in the ex- 

 periment of Galen, when it is tied upon a hollow tube ; where 

 it was converted into bone it could neither dilate nor con- 

 tract like bellows, nor transmit the pulsific power from the heart 

 to the inferior vessels ; it could not convey a force which it was 

 incapable of receiving through the solid matter of the bone. In 

 spite of all, however, I well remember to have frequently noted 

 the pulse in the legs and feet of this patient whilst he lived, for 

 I was myself his most attentive physician, and he my very par- 

 ticular friend. The arteries in the inferior extremities of this 

 nobleman must therefore and of necessity have been dilated by 

 the impulse of the blood like flaccid sacs, and not have ex- 

 panded in the manner of bellows through the action of their 



