. Biology; the story of living things. 286 THE MAINTENANCE OF THE INDIVIDUAL with their fangs and the toothless jawed turtles that make up for the lack of teeth by sharp cutting horny beaks suggestive of the bird's beak. The greatest development and specialization of teeth occurs among the mammals. According to their shape and function they are divided into incisors, or cutting chisels, canines, or graspers and tearers, premolars, or grinders, and molars, or crushers. Here we find a real relationship between the type of teeth and the diet of the organism. In the carnivores, for exam- ple, the
. Biology; the story of living things. 286 THE MAINTENANCE OF THE INDIVIDUAL with their fangs and the toothless jawed turtles that make up for the lack of teeth by sharp cutting horny beaks suggestive of the bird's beak. The greatest development and specialization of teeth occurs among the mammals. According to their shape and function they are divided into incisors, or cutting chisels, canines, or graspers and tearers, premolars, or grinders, and molars, or crushers. Here we find a real relationship between the type of teeth and the diet of the organism. In the carnivores, for exam- ple, the anterior grinders are so constructed that they slide like shears while the canines are specialized for grasp- ing animal food, the back molars tending towards degeneracy. In herbivorous animals except the rodents the front teeth, especially the canines, are reduced while the molars become greatly developed. The teeth of man play a definite role in the mechanical preparation of food for digestion. Instead of. Skull of a squirrel, a rodent (left), and a cat, carnivore (right). Compare carefully for differ- ences in dentition. holding the prey, they crush, grind, and tear the food so that a greater surface may be exposed to the action of digestive juices. Man like some other organisms develops more than one set of teeth. The first, or milk teeth, are only twenty in number while there are thirty-two secondary, or permanent teeth. Each tooth is divisible into an upper gum-protruding crown, a lower embedded root, and an in- termediate neck. The outer part of the crown is protected by the hardest substance of the body, enamel, that surrounds the bony dentine. This in turn protects JCTW. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Hunter, George W. (George William), 1873-1948; Walter, Herbert Eugene, b.
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