Elements of animal physiology, chiefly human . to overcome the force of cohesion, andthus promote the solution or liquefaction of the food. Itis effected by an up-and-down or vertical, an antero-posterior or front to back, and a lateral or side-to-side (the two latter together producing an ohlique) motionof the jaws. 248. Teeth.—Man is provided during life with two setsof teeth—the first of which appear during infancy—termedthe temporary, deciduous or milk teeth; the second set,which begins to appear during childhood, but which isnot, completed until the loisdom-teet^i have appeared,about the
Elements of animal physiology, chiefly human . to overcome the force of cohesion, andthus promote the solution or liquefaction of the food. Itis effected by an up-and-down or vertical, an antero-posterior or front to back, and a lateral or side-to-side (the two latter together producing an ohlique) motionof the jaws. 248. Teeth.—Man is provided during life with two setsof teeth—the first of which appear during infancy—termedthe temporary, deciduous or milk teeth; the second set,which begins to appear during childhood, but which isnot, completed until the loisdom-teet^i have appeared,about the commencement of adult life, are termed thepermanent teeth. 249. The Permanent Teeth, when complete, are 32in number: they are arranged in the form of arches in thesockets or alveoli of the upper and lower jaws. Each dental arch (gum) contains 16 teeth. These 120 ANJMIL fHYSIOLOG?. sixteen teeth contain four types, shapes, or varieties, asshown in the diagram (fig. 54)—viz., four incisor, twocanine, four bicuspid, and six molar Tang or,.Boot. Molars. Bicuspid, Canine. Incisors. —Showing Differently Shaped Teeth. 250. Insalivation is the process by which the foodduring mastication is mixed with air and saliva. Thesaliva facilitates swallowing by lubricating the food,—itmakes the starch in the food soluble, by ultimately con-verting it into sugar. It also makes the food morepermeable to the juices of the stomach. It promotestaste by dissolving the sapid substances in the food. 251. The Salivary Glands are the three pairs of con-glomerate glands which secrete the saliva. The largestare the parotid glands, situated immediately below and infront of the ear: they weigh from ^ oz. to 1 oz. ducts, about 2J inches long, open upon the innersurface of the cheek by orifices opposite the upper secondmolar teeth. The sub-maxillary glands are situated near the neck,in the lower jaw, under the floor of the mouth; theirducts, about 2 inches long, open under
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