The two great mediums through which energy is delivered to the human body, pure air and sunshine, are in large part denied immediate contact with its surface. Clothing prevents full elimination of perspiration and its products, which remain to be partially absorbed or to clog the pores of the skin. This defect can be remedied to a degree by daily exposing the naked body to the outer air for as long a time as can be spared from other duties. The air bath is a valuable adjunct to natural treatment for the prevention and cure of disease, and of equal worth is the action of the direct rays of the sun upon the skin. The human plant absorbs the tonic properties of air and sunlight with the eagerness of its garden counterpart, and these baths add their quota of benefits to the other hygienic means described. In the fast these two baths should form a daily habit.
The skin is the natural clothing of the body. Its protection to the parts beneath is aided by deposits of fat, a non-conductor of heat, distributed more or less uniformly over the body. When overheated, evaporation of perspiration cools ; when chilled, closed pores retain the body warmth. Like the lungs, the skin admits of blood oxygenation through
