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The blood vessels have, as yet, been but little 

 examined as to their chemical properties; and, 

 with the exception of Bi CHAT'S experiment of 

 macerating their various membranes, we have 

 no investigation on the subject. The fibrous 

 membrane of the arteries, which, unquestionably, 

 is the most remarkable of all, has long been 

 considered as composed of annular muscles. 

 This was the opinion of HALLE R, and on this 

 supposition he has founded his theory of tliefmlse, 

 which to this day is adopted in all our elementary 

 books. JOHN HUNTER disapproved HAULER'S 

 idea of the muscular action of the arteries, as 

 being the cause of their pulsation. BICHAT tried 

 to irritate the arteries of living animals, with 

 such chemical and mechanical stimuli as affect 

 the muscular fibre, but without being able to ex- 

 cite the least perceptible change in their motion ; 

 and he declared, in consequence of these experi- 

 ments, that the pulsation originated only in that 

 of the heart; that it did not consist in dilatation, 

 but was only a motion from its former place, or, 

 as he himself called it, a locomotion. The che- 

 mical examination of the fibrous membrane of 

 the arteries, now became of peculiar consequence, 

 as the only possible means to decide how far the 

 fibre of the artery was of the same nature as that 



