In contrast to the many uncertainties relating to angina pectoris is the circumstance that in a large proportion of cases the attack is only an incident in the history of arteriosclerosis. Since Edward Jenner demonstrated postmortem disease of the coronary arteries, the association of a lesion of these vessels with the disease has been accepted as one of the best attested facts in cardiac pathology. Not that it has helped much to explain the mysterious nature of the pain of the attack, or all of the phenomena of the paroxysm. Pain in arteriosclerosis, as we see it in other parts, deserves a more careful study than it has yet received. In the head there is the association of migraine with arterial disease, the severe and characteristic headaches of arteriosclerosis and high pressure, and the agonizing pain in some cases of embolism of the cerebral arteries, more rarely in thrombosis. Abdominal pain is not often due to vascular disease, though there are cases in which, from the situation and intensity of the paroxysm it might rather be called angina abdominis than pectoris. There may be severe pain in lesions of the mesenteric arteries and in thrombosis of the iliac vessels in typhoid fever. It is in sclerosis of the arteries of the extremities that we meet with the most remarkable disturbances of sensation. The pain in embolism or thrombosis of the femoral or popliteal arteries is very intense, particularly at the site of the lesion. In the ordinary sclerosis, particularly of elderly persons, there may be, first, simple paresthesiæ, the numbness and tingling so commonly complained of; secondly, attacks of painful cramps, usually slight and nocturnal, or recurring paroxysms of extraordinary intensity and deserving the name of angina cruris more than intermittent claudication, which Walton has applied to it; thirdly, the pain, not always present, in intermittent claudication; fourthly, the paroxysms of pain with erythema, etc., the arteriosclerotic type of erythromelalgia.