THE successful application of radiotherapy is due in large measure to the broad foundation laid in the exhaustive study of the immediate metabolic reaction and the tissue changes produced in man and the experimental animal. The literature on the immediate response of the body as regards metabolism, normal tissue and tumors is abundant, but that relating to chronic or terminal changes is far from being comprehensive. In recently reported experimental work on dogs it was demonstrated that a fatal nephritis could be readily produced by the application of hard X-rays through the body wall. This was accomplished both with single massive doses and with repeated smaller doses. In the first experiments large perforating ulcers were produced in the abdominal wall and the animals were lost from extensive destruction of the intestine, but the technic has been developed to the point where little or no hair is lost and only an occasional scar or ulcer of the intestine is found. However, when an area 10 cm. square over...