Circulation of the Blood 137 



But that the question under discussion, viz. that the 

 pulsific 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 experiment of Galen, when it is tied 

 upon a hollow tube ; where it was converted into bone 

 it could neither dilate nor contract 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 particular 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 

 expanded in the manner of bellows through the action 

 of their tunics. It is obvious, that whether an artery 

 be tied over a hollow tube, or its tunics be converted 

 into a bony and unyielding canal, the interruption to 

 the pulsific power in the inferior part of the vessel must 

 be the same. 



I have known another instance in which a portion of 

 the aorta near the heart was found converted into bone, 

 in the body of a nobleman, a man of great muscular 

 strength. The experiment of Galen, therefore, or, at all 

 events, a state analogous to it, not effected on purpose 

 but encountered by accident, makes it sufficiently 

 to appear, ihat compression or ligature of the coats of 

 an artery does not interfere with the pulsative proper- 



