enough of this moisture to be noticed it is called sensible perspiration. The purpose of perspiration is to cool the body whenever it is in danger of getting overheated. For the sake of grasping the situation more clearly bear the following facts in mind:

I. When a man is heated from exercise, capillaries in the exercised part of the body are stretched out with the blood which is forced into them.

2. If a heated man, covered with perspiration, sits in a draft, his blood is cooled, the capillaries of the skin contract, and the mass of the blood goes to some other place.

3. When this occurs, the linings of nose, throat, lungs, and intestines are apt to be overcrowded by the blood which has been forced into them from the skin, and the most sensitive lining suffers most. Usually the first symptom of a cold is that a man feels stuffy in nose, throat, or lungs. The explanation of the feeling is the distended capillaries, with another fact added. Although red corpuscles continue to deal with oxygen as they have always done, still the white corpuscles are now behaving strangely. They get together, many of them stick to the inside walls all along the length of the capillaries, and the more inactive they are, the less do they seize and destroy intruding microbes. These microbes, therefore, remain in the blood and continue such mischief as their nature makes possible.

When a man has a cold the trouble often is that influenza microbes have escaped the white corpuscles and have firmly established themselves in the part of the body which is congested with blood.

In view of these facts it is not hard to understand why a man who has a cold is so much more liable to take other diseases to which he is exposed. He is in a weakened condition, and already microbes instead of white corpuscles have the upper hand.

But suppose a cold is coming on, what does our knowledge of the laws of the skin direct us to do about it?

Draw blood away from the region of the cold as promptly as possible. Do it in several ways: take vigorous exercise until every sweat gland is active; take a hot bath; soak the feet in hot water; drink hot lemonade; go to bed; sleep warm; perspire freely. By keeping warm in bed the blood goes to the surface of the body, and delicate internal membranes are relieved of superfluous blood. White corpuscles are also stirred up, and restoration begins. Stay in bed until the feeling of cold is over. One night may suffice. When you leave the bed be specially careful to avoid every chance draft, for a draft just now will undo the good results of the heat treatment. Take a warm bath at once, then a quick wash with cool water. This will stimulate the nerves of your skin without chilling the blood itself, and keep you from taking cold afterwards.

If going to bed is out of the question, dress more warmly than usual, keep out of drafts, observe every law of general health, and determine to be strictly careful not to expose yourself to colds in the future.

Sitting in drafts or with damp feet, or with clothes damp from perspiration or from rain, is dangerous because in these ways the body may be chilled. A quick, cold, two-minute bath with a hard rub afterwards acts as a tonic and not as a chill to the body.

Let a man live in central Africa or let him travel to the coldest land; let him stay in the burning heat of his city home or wander in the cool shadows of the country; let him be in bed or in the harvest field, in the countinghouse or in the mine; wherever he is, he will find that if he is well the thermometer under his tongue always indicates about ninety-eight degrees of temperature.

In each place also, even if he is not well, the heat of his body will change but little. We say that a man has a slight fever if his temperature is 100° F. If it reaches 102° we grow somewhat troubled; if it rises to 103° and then to 104°, we are truly anxious; for no man is expected to live after his temperature has reached a higher point than 107°.

It is well for us that the body has this power to keep the blood warm independent of outside conditions; for if it were otherwise, if we were as cold-blooded as is the frog, we should be as useless in cold weather and in cold places as he is. We should have to hibernate in winter as he does.

Birds, as well as all animals that begin life by taking milk from their parents—mammals they are called—are warm-blooded. Each has for itself this wonderful power of meeting the changes of the weather with a constant temperature of its own. As a result, such animals are generally warmer than the surrounding air, and are called warm-blooded for this reason.

Cold-blooded creatures usually feel cold to the hand when we, who are warm-blooded, touch them. Their bodies have no power to stay warm when the air is cold about them.

Although this power is part of our possession, it is nevertheless true that even the heat of our warm bodies can fail. Men do freeze to death. They cannot endure a freeze and then come out of it again, as does the coldblooded frog. People may live in the coldest countries and be active and healthy there, but the one condition is that they help the body do its work by preventing the escape of more heat than the same body can promptly replace.

Never confuse these two facts:

1. The inside heat of the body changes little from year's end to year's end. If it changes many degrees up or down, we die.

2. The skin feels warm or cold as the air about it changes. Skin and nose and toes may freeze, but the inside temperature remains practically unchanged.