These experiments indicate that atrophy of bone does not result from denervation of an extremity, or from immobilization of a denervated extremity. When atrophy of bone was observed, in rare instances, it occurred as the result of ulceration, overlying the bone and joint. When ulceration occurred in extremities which had been immobilized and denervated, it was more severe than in cases in which the extremity had not been immobilized, and a greater number of cases of bone atrophy occurred.