OP THE VEINS. 293 



times inflammation terminates in the gangrene of the tumour, 

 and either of the effects here above mentioned may be the 

 result of the separation of the eschar. Finally, at other times, 

 the circulation imperceptibly diminishes in the artery affected 

 with aneurism, and becomes at the same time more and more 

 active in the collateral passages or vessels, from which finally 

 result the obliteration of the affected artery as far as the neigh- 

 bouring branches of the tumour, and the gradual absorption 

 of the latter. 



436. Arteries, inflamed or affected with an accidental 

 production in their parietes, or without any apparent cause, 

 instead of dilating and tearing, are sometimes narrowed, and 

 even are obliterated spontaneously. Thus the aorta has been 

 observed narrowed and even altogether obliterated; the total 

 obliteration of the right pulmonary artery has also been re- 

 marked. I have seen once that of the carotid artery, several 

 times the narrowing of the caliber of the brachial trunk, and 

 often the narrowing and obliteration of the crural trunk and 

 of its branches. This is the ordinary cause of senile gangrene 

 of the toes, feet and legs; this change occurring in a part and 

 at a time in which the arterial branches, they themselves 

 being affected with hardening, are no longer susceptible of 

 rapid growth, necessary to the re-establishment of the colla- 

 teral circulation. 



SECTION III. 



OP THE VEINS. 



437. The veins* are the vessels which bring back to the 

 heart the blood from every part of the body. 



438. We have already seen that the ancients have at first 

 made no distinction between the veins and arteries. Galen, 



* Diatribe anatomico-physiobgica de strudura atque vita venarum, Au- 

 tore H. Marx, in 8vo. Carlsruhze, 1819. 



