_Dressing the Hair._—Dragging or twisting the hair from its natural direction, pulling it into constrained or artificial positions, and even twisting the hair very tightly is injurious to it. The curling iron acts by abstracting more moisture on one side of the hair than on the other. The stronger the hair, the more easily it will curl, and the longer it will stay curled. The daily use of a hot iron, notwithstanding the greatest care, will in a short time prove injurious; the hair is apt to become thin and fall out. Its growth is interfered with. The use of kid curlers is much less injurious, but even here the tight twisting of the hair around the kids is said to be harmful. Shell hair-pins are the best for the hair. If steel ones are used, the points must be smooth and the pins kept in good condition. When the hair is dressed for the night, after the scalp has been brushed and massaged, it should be loosely braided and left hanging down. Cutting the hair 1 inch, every two or three months, is said to promote the growth of the hair and prevent its splitting. It does not increase the number of hairs. There is no truth in the assertion that the hair is a hollow tube, which allows the escape of oil, and that if the ends are sealed by singeing much good will result. =Gray Hair.=—Grayness of the hair may be either premature or physiologic. When the grayness is due to some temporary cause, as anxiety or some diseased state, the process may cease completely on the removal of the cause. Usually the whitening is permanent. The grayness of the hair is caused by obscure changes in the nutrition of the hair-papilla, which interfere with the production of the pigment. As a rule, the hair whitens first on the temples, then on the top of the head. The hair first turns gray at its root. The grayness is due to the loss of pigment. Prolonged residence in either a very cold or a very hot climate will cause the hair to turn gray. A yellowish tinge of the hair is sometimes seen in patients with jaundice, or gray hair may owe its dull yellow color to the tint of dry albumin of which it is composed. The glitter of steel-gray or silver-white hair is due to the high refractive power of the minute air-bubbles that lie in the substance of the hair. _Treatment._—The color cannot be restored to gray hair. The roots of the hair are embedded in the hair follicles, and cannot be reached by any fluids applied to the scalp. Not only is the use of hair-dyes to be deprecated as an exhibition of poor taste, which happily is going out of fashion, but the use of hair-dyes is extremely dangerous. Cases are being constantly reported by physicians, where the use of these supposedly simple vegetable hair-dyes has been followed by very serious and extensive dermatitis of the face, neck, and shoulders.