often the cause of unexpected death after operations. The kidney affection in the patient is so slight as to have been unsuspected, or to have been considered of not sufficient importance to render the operation especially dangerous. After kidney disease the most important factor in the production of unexpected death is heart disease. In about 60 per centum of the patients who die suddenly, in the midst of seemingly good-health, death is due to heart disease. All forms of heart disease may be considered under two heads--the congenital and the acquired. The congenital form of heart disease usually causes death in early years. If such patients survive the fourth or fifth year, they are usually carried off by some slight intercurrent disease shortly after puberty. A few cases of congenital heart disease, however, live on to a good old age and seem not to be seriously inconvenienced by their heart trouble. Most of the acquired heart disease, that is, at least 65 per centum of it, is due to rheumatism. All of the infectious fevers, however, may cause heart disease, and scarlet fever especially is prone to do so; heart complications occurring in about one out of every ten cases. The probabilities of sudden death in a case of heart disease depend on what valve is affected and what the condition of the heart muscle is. Most of the cases of sudden death occur in disease of the aortic valves, that is, of the valves that prevent the blood from flowing back from the heart after it has been pumped out. Diseases of the other side of the heart, the mitral valve, cause lingering illness until the heart muscle becomes diseased, when sudden death usually closes the scene. Diseases of the aortic valves of the heart cause visible pulsations of the arteries, especially of those in the neck. This readily attracts attention if one is on the lookout for it. Deaths in heart disease, whether sudden or in the midst of apparent health, or as the terminal stage after confinement to bed because of weak heart, are apt to occur particularly during continued cold or hot spells. Each of the blizzards that we have had in recent years has been the occasion for a {141} markedly increased mortality in all forms of heart disease. The cold itself is exhaustive, and the heavy fall of snow, by delaying cars and modes of conveyance generally, is very apt to give occasion for considerably more exertion than usual. Besides, cold closes up the peripheral capillaries and makes the pumping work of the heart much harder than before. At times of continued cold, in our large cities particularly, the ordinary arrangements for heating the house fail to keep it at a constant temperature, and this proves a source of exhaustion to cardiac patients.