PHYSICAL AND LITERARY. 247^ 



the two which were fituated in the hams 

 of John Parker, which both extended 

 backwards, and by the hiftories related 

 of true aneurifms, proceeding from an in- 

 ternal caufe. Aneurifms of the aorta, at 

 its beginning and curvature, however, 

 are exceptions to this rule j for here we 

 find, that they have generally protruded 

 either forward towards the fternum, or 

 upwards towards the neck, as the ftream 

 of blood coming from the heart ftrikes 

 ftronger againft the forepart, and the up- 

 per fide of the curvature of the aorta, 

 than any where elfe . 



In the true aneurifm, the pulfation I 

 believe, for the moil part continues ftrong 

 till the coats of the artery burft, and the 

 aneurifm becomes a mixture of the true 

 andof thefalfe kind; after which, indeed, 

 the tumour often increafes confiderably, 

 large polypous concretions are formed, 

 and the pulfation ceafes. Many authors 

 tell us, that the pulfation frequently 

 ceafes before the aneurifm burfts ; this 

 gften happens in fajfe aneurifms ; but, 



from 



