By a small addition of vegetable to the protein diet, the lives of the animals were prolonged at will. With this modification of the experiment, the findings in the vessel walls were noticeably altered. The changes affected chiefly the intima, to less degree the media, and histologically were very much like human intimal disease. I have been unable to produce the slightest arterial lesions in rabbits by intravenous injections of lead. Frothingham had no success feeding animals with lead. In a study of autopsy material from persons up to 40 years, who died of infectious disease, he found changes in the arteries of those who had succumbed to infection with the pus cocci or to very severe infectious disease. These changes were, however, localized, and were not like those of the general diffuse arteriosclerosis. Adler has recently reported experiments on dogs, to which he fed or injected intravenously various substances supposed to induce arteriosclerotic changes. He was unable to find any arterial lesions comparable to human arteriosclerosis. The difficulty experienced by experimenters is not surprising when the character of the changes is considered. Arteriosclerosis is not an acute process. In its very nature, it is of months' or years' standing, the specific changes are of slow growth, and more in the nature of degeneration. It would seem that a very careful study of the histories of those with arteriosclerosis and a final examination upon the actual tissue might eventually give us data for the etiology. The most frequent site of disease in these experimental lesions is the thoracic aorta, and it is there also that the most severe changes are seen. While the toxic action is felt in the vessels all over the body, the lesions are, as a rule, scattered and small. The thoracic aorta stands the brunt of the high pressure, and this combined with the poisonous action of the drug or drugs, results in the formation of a fusiform aneurysmal dilatation which stops at the diaphragmatic opening. The aortic opening in the diaphragm seems to act as a flood gate, allowing only a certain amount of blood to flow through, and thus the abdominal aorta is protected to a great extent from the deleterious effects of increased pressure. Focal degenerative lesions are, however, found in the abdominal aorta. Changes somewhat analogous to those found in the human aorta as the result of intimal proliferations, are produced in animals by the toxins of the typhoid bacillus and the Streptococcus pyogenes. Clinically, Thayer and Brush have found that the arteries of those who have recovered from an attack of typhoid fever are more palpable than the arteries of average individuals of equal age who have never had the disease.