At the beginning of the present century, Bichat, a distinguished French physician who revolutionised medical practice, said that health and the favourable or unfavourable termination of disease depends on the condition of three sets of organs--the brain, the heart, and the lungs. This was what he called the vital tripod. It was not until nearly thirty years after Bichat's death that Bright, an English {137} physician, taught the medical profession to recognise kidney disease. Since his time we have learned that even more important than Bichat's vital tripod, as regards health and the termination of disease, is the condition of the kidneys. We shall consider affections of these four organs, and their influence on the human system and intercurrent disease, in the order of their importance. When kidney disease exists the individual's resistive vitality is much lowered. The kidneys are the organs which serve to excrete poisons that find their way into the circulation. When the kidneys fail to act, these poisons are retained. As a result other important organs, notably the nervous system and the heart, suffer severely because of the irritating effect of the retained poison. A patient with kidney disease runs a very serious risk in any infectious fever, no matter how mild, and such patients should always be completely prepared for a fatal termination when they acquire any of these diseases. Nephritic patients bear operations very badly. The shock to the nervous system incident upon operation always throws a certain amount more than usual of excrementitious material into the circulation. Diseased kidneys do not fulfil their function of removing this at once, and the result is an irritated and fatigued nervous system. Anaesthetics, that is, chloroform and ether, are not well tolerated when nephritis exists, and this adds to the danger of operation in such patients. No matter how simple or short the operation that is to be performed on a person suffering from kidney disease, if an anaesthetic is to be administered it would be well to prepare the patient for an untoward event that may occur.