MASTICATION, or CHEWING, the thorough subdivision of food in the mouth so that it can be readily acted upon by the gastric juice and other digestive secretions. The tongue, cheeks and lips push the food material between the teeth, and by the lateral and up and-down motions of the lower jaw it is cut and torn by the incisor, canine and bicuspid teeth and bruised by the molar or grinding teeth. During ,these actions the food is sof tened by the saliva (insalivation), which exudes abundantly from the salivary glands by the act of mastication. Typical mastication is seen only in the higher vertebra. "The am phibian bolts its fly, the bird its grain, and the fish its brother without the ceremony of chew ing,' but in man and the higher animals masti cation is necessary for complete and comfort able digestion. Thorough comminution of food by mastication is analogous to the pulverizing process employed by the chemist, but associated with mastication is insalivation, as it is almost impossible to swallow substances which are very dry. Imperfect mastication of food, either by reason of rapid swallowing (bolting), or because of the absence of sound and service able teeth, is very frequently the cause of the numerous ailments classified under the term indigestion. Exaggerated mastication which has been so highly recommended by certain per sons as almost to constitute a panacea or com plete prophylaxis is known to lessen the secre tion of gastric juices which is started by sen sations of taste, to protract beyond desirable limits the time required for proper gastric di gestion, to develop the salivary deposit in a proportion relatively too great when compared with the secretion of the pancreas. It is more
over known that the teeth are likely to wear out too soon, if mastication is carried beyond a reasonable time.
Exaggerated mastication and the fancied ad vantages accruing from it are an illustration of an indulgence in a form of securing the grati fication of an unconscious desire. In infancy a great pleasure is derived merely from mouth ing different objects, a pleasure originating in the mode of absorbing the early meals at the mother's breast. It has been discovered by studying the unconscious wishes of mankind that the sexual desire in the adult is a syn thesis of different partial desires which in the infant are satisfied in different parts of the body, now here, now there, but which in the adult are assembled in the genital organs or are at least unified under the supremacy of the genitals. But it has been definitely proven that in some individuals this synthesis has never been successfully accomplished. Either the mouth pleasure zones or the anal or the skin or some other zone which gave in infancy a quite sense of gratification has failed of appropriate subordination, and has persisted into adult life, with some individuals, as a source of extraordinary pleasure. To this class of partially undeveloped minds belong not only the advocates of exaggerated mastication but all other persons who develop any other form of activity as a fad such that they are noticeably peculiar in that respect.