During the past few years lesions affecting the blood vessels of the extremities have been well differentiated and the clinical syndromes associated with them have become well recognized. It may be said, however, without much fear of contradiction, that most things concerning the etiology of the changes in the vessels leading to spontaneous gangrene and many things concerning the results of these are still in a state of distressing uncertainty. Clinically, spontaneous gangrene occurs in the old and in the relatively young, thus justifying the clinical classification of senile and presenile gangrene. These are dependent on entirely different processes, one degenerative in character, and the other inflammatory—an arteritis or, because of the almost constantly associated involvement of veins, a thrombo-angiitis. According to Marchand, the term arteriosclerosis includes all those changes occurring in an artery which lead to a thickening, especially of the intima; to degenerative changes (fatty degeneration); to sclerosis