ANEURISM OF THE AORTA. 417 



ranted that the affection is also present in the aorta, in a still more 

 advanced stage of development. As the vessels have become dilated, 

 and their walls more rigid, the pulse generally feels hard and full ; the 

 course of the elongated arteries is remarkably sinuous, their curvature 

 increasing with the beat of the pulse, which becomes visible. The 

 artery, even when undistended by the current of the blood, can usually 

 be felt as a hard, irregular cord. 



As long as there is no aneurismal dilatation of the aorta, percussion 

 and auscultation do not aid the diagnosis. In rare cases, false mur- 

 murs arise, in consequence of roughness of the inner coat of the aorta, 

 and where there is no deformity at the ostia. 



According to Bamberger, the first sound of the aorta is often dull, 

 muffled, or even inaudible ; the second, particularly if the walls of the 

 great vessels be studded with bony plates, and as long as the valves 

 retain then* efficiency, has a remarkably loud and metallic ring. 



CHAPTER II. 



ANEURISM OF THE AORTA. 



ANEURISMS, produced by wounds, belong to the province of surgery. 

 Spontaneous aneurism, that is to say, partial dilatation of a vessel 

 caused by degeneration of its walls, is the only form of the disease 

 which occurs in the aorta. 



Uniform dilatations of the entire tube, such as arise in hypertrophy, 

 and which take place above stricture of the vessel, are not regarded 

 as aneurisms. 



ETIOLOGY. The degeneration of the aortic wall, which most fre- 

 quently gives rise to aneurism, is the result of the chronic endarteriitis 

 described in the previous chapter, and known as atheroma. 



Next in frequence, as a cause of aneurism, is simple fatty degenera- 

 tion of the inner and middle arterial tunics, a disease which we have 

 purposely avoided mentioning hitherto, as it has nothing in common 

 with the inflammatory affection previously described. In simple fatty 

 metamorphosis there is no preliminary thickening, and cell-growth in 

 the tunica intima ; but, from the very outset, we find opaque, whitish 

 or yellowish-white spots, grouped in a peculiar manner, and but slight 

 *y prominent above the surface, which consist of deposits of fat mole 

 cules in the tissue of the arterial coats. 



Thirdly, simple atrophy, and thinning of the aortic wall, which 

 seems to be by no means uncommon among elderly people, may be a 

 cause of aneurism. 



Whether palsy of the vaso-motor nerves be also a cause of this 



