Air is carried into the lungs in respiration and by the action of Innate the oxygen is absorbed in the air cells and passes into the blood. It is carried in the blood by the hemoglobin to the tissue cells where it comes in contact with the calorific mental impulses and combustion takes place. Body Heat The normal bodily temperature is 98.6° F. Variation above or below this point indicates abnormality. This heat can not be supplied artificially from without. It must be generated within the body. It therefore becomes obvious that the temperature outside of the body is not regulated for the purpose of supplying the body with heat. The temperature of the atmosphere must, however, be regulated in order that there may not be an abnormal loss of the bodily heat. The bodily heat is being constantly lost to the outside air as follows: 30% by contact with the air, about 43% by radiation and about 27% by exhalation and other losses. We may sit in a room that is warm enough, say 75° F., and yet if we are near a cold wall we will feel chilly. We say we feel the cold coming from the wall, while in reality we feel chilly and cold because the body is losing its heat abnormally to the cold wall by radiation through the air. When the air is comparatively dry the equality of the bodily heat is maintained by a steady but imperceptible evaporation from the skin. In moist air this evaporation does not take place so readily since the air is already laden with moisture, so instead of the moisture being absorbed by the air it forms on the surface of the body as perspiration. This is why one perspires more in a moist air than in an atmosphere having a low humidity. When the air is kept in constant motion there is an increase both in the evaporation from the surface of the body and also in the heat conduction by the constant supply of fresh air to take the place of the moisture-laden and heated air around the body. The normal heat given off from the body raises the temperature of the air surrounding the body and tends to create upward currents. This is Nature’s method in freeing the body from the envelope of vitiated air which surrounds it as a result of the natural processes carried on through it. Therefore, if the temperature of the room is too nearly the same as that of the body it will be necessary to make more provision for the ventilation since the temperature of the body would not be enough greater than that of the surrounding air to create sufficient movement to carry the vitiated air away from the body. That is why a cool room does not require the same amount of ventilation that a hot room does.