THE CIRCULATORY SYSTEM. 



455 



ton corresponding with the primary form of Thoma j- 2d, a senile form, in 

 which there are often great distortion of the vessels, calcification, and fre- 

 quent thinning of the walls. Atrophic changes in the viscera are apt to 

 be associated with this form of senile arteritis ; 3d, a diffuse form of 

 marked obliterating endarteritis with fibrous involvement of the muscu- 

 lar layer. This is apt to be associated with hypertrophy and often with 

 dilatation of the heart, and with chronic diffuse nephritis often with atro- 

 phy. The arterial changes may be marked in the liver as well as in the 

 kidneys. 



Tuberculous Arteritis. Tuberculosis of the arteries is usually second- 

 ary, the process extending to their walls from an already established 



FIG. 354. TUBERCULOUS ARTERITIS IN THE LUNG. 



Showing the encroachment of an area of tuberculous inflammation upon the wall of the artery and the 

 formation of a mass partly occluding the lumen of the vessel. This section shows how the generalization of 

 the tuberculous inflammation through the body may occur by the sweeping away of the tubercle bacilli by 

 the blood and the establishment of new foci in various parts of the body. 



focus (Fig. 254). Tubercle tissue with necrosis may involve the external 

 layers, while an obliterating inflammation often closes the lumen. . Thus 

 it is that in tuberculous cavities of the lungs large arterial trunks may 

 be laid bare (see Plate X. ) without a distribution of the bacilli through 

 the body and without haemorrhage. Tuberculosis of the aorta is of occa- 

 sional occurrence. ' 



Syphilitic Arteritis. In the more characteristic forms of this lesion 



l Stroebe, Centralbl. f. Pathologic, Bd. viii., p. 998, 1897, bibliography. Consult 

 Bl timer, American Jour, of the Med. Sciences, vol. cxvii., p. 19, 1899, bibliography. 



