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 serum of the blood also destroys the germs by the antitoxins in it. Inflammatory troubles are: colds, rheumatism, diarrhœa, and all diseases with name ending "itis." An inflamed part is red, swollen, hot, and painful.

Prevention and Care of Colds.—A cold is an inflammation of a mucous membrane. Colds are prevented by so living as to encourage a free, vigorous circulation, and especially by not coddling the body so tenderly that the circulation becomes deranged by the least exposure. The circulation may be deranged by overheating as well as by chilling the body; usually it would be more appropriate to say that the person caught "a hot" than "a cold." At the first sign of a cold vigorous exercise, a cold bath, or going outdoors into cold air may aid in sending fresh blood to remove the stagnation and stop the inflammation. A warm foot bath and hot drinks may relieve by drawing blood from the congested mucous membrane. After the cold has become fixed such measures will not help, but the cure is aided by helping the skin to keep its full share of blood. The cold must run its course. The cells will be given every chance to repair the injury and destroy the germs (if any) by avoiding hard work, eating moderately of digestible food, avoiding drugs, especially infallible drugs advertised in newspapers, even if recommended by otherwise intelligent people. Repeated colds tend to become a disgusting disease called chronic catarrh. Constricting the blood vessels of the skin causes congestion of the (internal) mucous membranes. A skin tenderly protected constricts more readily than one accustomed to cold. Cold is the best preventive of cold. Cold baths, pure air, light clothing, free breathing, moderate eating, ward off colds. Fussing with sprays, gargles, and drugs will not; for the main factor in bringing on a cold is not germs, nor temperature, but the state of the system itself. Persons who have suffered much with colds have found that after substituting cotton underwear for woolen, colds became very rare. Linen will have a similar effect, but it is not as durable, soft, or heat-retaining as cotton (see p. 16).

—1. Through what kind of skin do the blue veins in the wrist show most plainly? 2. Which is more compressible, a vein or an artery? 3. Why are those who take little exercise likely to have cold feet? (p. 57.) 4. Where does the so-called venous blood flow through an artery? 5. What vein begins and ends in capillaries? (The portal vein, colored Fig. 5.) 6. To what purifying organ, after leaving the lungs, does the heart send part of the blood for further purification. (Colored Fig. 5.) 7. What keeps the blood moving between the beats of the heart?