In infants, gentle pressure of the fingers upon the chin is sufficient to cause wide opening of the mouth. An older child will frequently open the mouth when requested, but if he refuses, the finger, or, far better, the handle of a spoon, or some other smooth, flat instrument, may be inserted in the mouth, and downward pressure made upon the tongue, when the jaws will be widely separated. In some cases, when the child is old enough to do as he is bid, the fauces can be seen by directing the mouth to be opened wide and the tongue to be alternately protruded and retracted, or a prolonged sound of "Ah" to be made. With the refractory, and always with infants, the tongue has to be held down by a spoon-handle or tongue-depressor. If there be resistance, the patient must be taken on the lap of the nurse, who holds his back against her breast, directs his face toward a bright light, and controls the movements of his hands and feet.

The healthy oral mucous membrane has a deep pink color, and is smooth, moist and warm to the touch. The color is deeper on the lips and cheeks, lighter on the gums. The latter, up to the sixth month, as a rule, have a moderately sharp edge. Subsequently, the edge begins to broaden and soften, and the color of the investing mucous membrane deepens to a vivid red, and becomes hot, as the teeth begin to force their way through.

The tongue should be freely movable. It is pink in color, and the dorsum or upper surface, marked in the centre by a slight longitudinal depression, has a velvety appearance, and is soft, moist and warm to the finger. The velvety nap is due to the numberless hair-like processes of the filiform papillae. There are also scattered over the surface, but most closely at the tip, a number of eminences, the size of a small pin's head, circular in outline, and deeper pink than the general surface - the fungiform papillae. While far back, defining the papillary layer, are the circumvallate papillae, numbering about twelve, and arranged in a V-shaped row. These have the form of an inverted cone, surrounded by an annular elevation.

The hard palate, or roof of the mouth, is roughened anteriorly by transverse ridges. The soft palate - its continuation - is smooth, and its mucous membrane is paler than that of the rest of the mouth. The fauces, or walls of the throat, on the contrary, are redder. In the triangular recess between the half arches of the palate the tonsils can always be seen. They should be about the size and shape of almond kernels, and they present a number of circular openings, the orifices 6i pouches, into which the follicles open. The uvula - or, in popular language, the palate - is short and tongue-shaped. The posterior wall of the throat should be red, smooth and moist.

Examples of Variations in Disease. - Fever makes the mouth hot and dry, and causes the tongue to be frosted or coated. Affections of the stomach and bowels are usually attended by coating of the tongue. Inflammation of the mouth itself reddens the lining membrane, makes it hot and tender to the touch, increases its moisture, alters the surface of the tongue and leads to the formation of aphthae and to ulceration.