The skin is a heat regulator, and in this, its most important work, it is aided by the two million or more sweat-glands which are distributed over almost the entire surface of the body. The skin and the sweat-glands work together to keep the blood at an even temperature, either by giving off heat or in preventing this process in case the outside air is too cool. The body temperature, as a rule, is higher than that of the outside air, so that heat is generally being given off by the skin. We are perspiring constantly, but usually to such a slight extent that the fact is hardly noticeable. The amount of heat which is thrown off at any time is proportional to the amount of the tissue burned up by muscular action. CHAPTER V Health, strength, and efficiency! Surely every man in this great Republic of ours wants to be healthy, strong, and efficient, but how is he to obtain and maintain this threefold blessing? It has been stated that scientific physical exercise, preferably taken in group association, will accomplish it. Now to consider some of the practical details involved. THE ORGANIZATION The organization may be composed of any number from sixteen to one hundred men, and about the smallest unit that should be undertaken is that of sixteen men. On the other hand, when the number gets above one hundred (or preferably ninety-six, in order that it may be divided into four companies of twenty-four each) it is better to start a second group under a separate leader. The first thing to do in the organization is to enroll at least one physician, who becomes the surgeon of the company. His name, together with that of the secretary of the unit, should be filed with the Senior Service Corps, of New Haven, Connecticut, or with the National Security League, of New York City, in order that any additional information or directions may be forwarded promptly. The division of labor in the work should be from ten to fifteen minutes of the setting-up exercises, and from forty-five to fifty minutes of the outdoor work. It has been found upon scientific test that this is the best division, and the outdoor work should follow the setting-up exercises immediately, since the men are then in condition to benefit from the fact that they have opened up their chest cavity and are taking in more fresh air and oxygen. The best way to start a unit is to get ten or a dozen leaders together at dinner or luncheon and organize; then pick out other men who are of importance in the community and add them to the charter number. The editors of the local papers are usually very glad to lend their powerful assistance toward the project. It is not necessary to have the outdoor work partake of the nature of military drill, but a certain amount of this, added after the second or third week, lends interest and also produces excellent results in muscular control.