temperature. The temperature of the blood is due to the amount of combustion taking place in the tissues, and the amount of combustion taking place in the tissues is due to the amount and energy of their blood supply, which last depends upon the force of the heart’s action and the size of the blood-vessels which have the power of contracting and dilating, and which are subordinated to the regulating influence of the nerve-centres. If that part of the nerve-centres (the upper part of the spinal cord) which controls the size of the vessels be injured or destroyed, the combustion processes going on in the body seem to get beyond control and the temperature may be dangerously increased or decreased, the exact reason of one or the other phenomenon not being known. The limits of body temperature which are compatible with life are not very wide; for if the temperature rise to 109° or sink to 76° death will inevitably result, and a rise or fall of 7° from the natural temperature is decidedly dangerous. Seeing how narrow are the limits of temperature within which life is possible, we cannot but be amazed at the marvellous arrangements for maintaining the normal level of animal heat. The body is cooled by the evaporation going on from the lungs; by the more important evaporation going on from the skin (every one who has covered a portion of the skin with spirit and has encouraged its evaporation by blowing upon it knows practically the cooling effect of evaporation), and by the radiation of heat from the surface of the body, and the conduction of heat from the body by things in contact with it.