Hunter gives a very long and detailed description of all the parts constituting the oral cavity and the masticatory apparatus. He sought to establish a scientific nomenclature for the teeth, and in fact the denominations of _cuspidati_ for the canine teeth and of _bicuspids_ or _bicuspidati_ for the small molars originated with him. Hunter says that the enamel of the teeth is a fibrous structure, and that its fibers depart from the body of the tooth like rays. He believes it to be entirely inorganic, as it is absolutely impossible to convert it into animal mucus. The tooth is constituted for the most part by a long mass (it is thus he calls the dentine), which is, however, much harder and denser than any other bone. This part of the tooth is formed of concentric lamellæ, and is vascular, as is proved by the exostosis of the roots and the adhesions that exist at times between the roots and the alveoli. Hunter gives a good description of the pulp cavity and of the pulp itself. He studied odontogeny with great care, as is demonstrated by his special researches on this point. He admits the existence of distinct germs for the enamel and for the dentine. According to him the incisors are formed from three points of ossification, the canines from one, and the molars from three or four. The tooth after its eruption is an extraneous body “with respect to a circulation through its substance, but they have most certainly a living principle by which means they make part of the body, and are capable of uniting with any part of a living body.” The milk teeth, says Hunter, are not shed by a mechanical action of the second teeth, but by an organizing law of Nature. The physiology of the masticatory apparatus is treated by Hunter with great accuracy and most extensively. This author combats, by many arguments, the opinion that the teeth grow continually; he explains the apparent lengthening of those teeth whose antagonists are wanting, by the tendency of the alveoli to fill up, which, however, is not possible in normal conditions, because of the constant pressure exercised upon the teeth by their antagonists.