632 



THE TEETH. 



lower ends of the pear-shaped spaces wavy canaliculi originate, which freely 

 anastomose with each other, and traverse the whole mass of the central por- 

 tion of the crown in a prevailing radiate arrangement. Their number is more 

 scanty than in the regular dentine, so much so that relatively large territories 

 of the basis-substance are altogether devoid of canaliculi. The latter hold 

 delicate beaded fibers of living matter, as well as the canaliculi of normal 

 dentine, with the exception that on the average the fibers of normal dentine 

 are finer than those of the secondary formation. Some of these fibers are pro- 

 vided with lateral conical offshoots, directed toward the basis-substance, 

 which itself shows a delicate reticular structure, 

 of essentially the same character as I have seen 

 in regular dentine. (See Fig. 273.) 



The middle portion of the pulp-cavity is 

 bounded by a narrow zone of dentine, which is 

 possessed of canaliculi in a smaller number than 

 the main mass of dentine. This zone, besides, 

 is characterized by a deep carmine stain, while 

 the regular dentine remained almost unstained. 

 The stained portion is inserted upon the regular 

 dentine by means of numerous shallow excava- 

 tions, and its surface is irregularly jagged toward 

 the pulp-cavity. In the apex of the root the irregu- 

 lar formation of dentine again is much thicker 

 than in the middle portion, and provided with 

 numerous roundish spaces, all of which contain 

 plastids, and communicate with the irregular, 

 wavy canaliculi of the boundary layer of the 

 pulp-cavity. 



In the tooth just described we have a forma- 

 tion which is known by the term " secondary 

 dentine." The literature of this subject is con- 

 cisely presented by Carl Wedl,* from whom I 

 quote the following note : 



" J. Hunter t says : 'In teeth which are worn 

 away by attrition, that portion of the pulp-cavity 

 adjacent to the abraded surface becomes filled 

 with a new substance, which occupies the center 

 of the abraded surface, and generally is softer 



than the rest of the tissue of the tooth.' ProchaskaJ treated of the same 

 subject in his ' Observat. Anatom. de Decrement Dentium Corp. Humani.' 

 Oudet gives a good description of these new formations, which he divides 

 into two classes the adherent and unattached. He paid no attention to 

 their histological structure. . . . R. Owen || illustrates numerous new 

 formations of osteo-dentine, but does not go very deeply into the subject. 

 Salter If treats of osteo-dentinal formations in addition to simple calcifica- 



FIG. 272. ROOT OF AN 

 ANOMALOUS CANINE 

 TOOTH. 



D, dentine ; C, cementum ; P, 

 pericementum. Magnified 1000 

 diameters. 



"The Pathology of the Teeth," Philadelphia, 1872. 

 t " Natural History of the Teeth," 1778. 

 % Adnotat. Academ. Prag, 1780. 

 " Dictionnaire de Mtidecine," article "Dent," 1835. 

 || " Odontography," 1840-45. 

 IT Guy's " Hospital Reports," ix. 



