THE TEETH. 651 



can furnish no direct proof, I consider the prolongation of the nerve-fibers 

 into the dentinal canaliculi as certain, the direction of the ends of the nerves 

 being parallel with the canaliculi. In the dentine near the pulp, we have, 

 therefore, to assume two varieties of canaliculi : those containing the proc- 

 esses of the peripheral cells of the pulp, and others, which receive the minute 

 nerve-fibers emanating between these cells." 



J. Bruck, Jr.,* says that the structure of dentinal new formations is iden- 

 tical with normal dentine, with the difference that in the former the canaliculi 

 assume a radiating arrangement and a wavy course. Such new formations 

 are found not only in carious, but frequently in healthy, temporary and per- 

 manent teeth. He states that all formations which previously have been 

 described as depositions of lime-salts within the pulp are nothing else but 

 new formations of dentine. Dentinal tissue may develop not only from the 

 odontoblasts, but from any cell of the pulp-tissue. 



John Tomes t asserts that the odontoblasts are in actual contact with one 

 another, and there is no room between them for an intercellular substance. 

 The most external portions of the odontoblasts undergo a metamorphosis into 

 a gelatigenous matrix, which is the seat of calcification, while their most cen- 

 tral portions remain soft and unaltered, as the fibrils. According to this view, 

 the fibril, the sheath, and the matrix are but three stages in the development 

 of the same tissue. 



Carl Wedl t says that the outer surface of the pulp is covered with conical 

 cells, the odontoblasts, from the broad faces of which, directed outward, 

 comparatively thick processes extend ; these enter the dentinal canals. The 

 basis-tissue of the pulp consists of a loose connective tissue. The greater 

 portion of the very common osteo-dentinal formations is composed of dentine ; 

 the bony substance occurs in a very small amount, and may consist merely of 

 a group of a few bone-corpuscles. With regard to the development of these 

 isolated, encysted new formations, Heider and I have maintained the view of 

 the occurrence of an inversion of the layer of dentinal cells. The calcareous 

 grains are true concrements, and occur in connection with hard new for- 

 mations, but never enter into organic union with the original dentine. They 

 are located within the parenchyma of the pulp, and are calcifications in the 

 connective tissue. 



According to Waldeyer on the odontoblasts, which are arranged so as to 

 form a kind of columnar epithelium, three kinds of processes may be distin- 

 guished : the dentinal process, the pulp process, and the lateral processes. 

 The first constitutes the dentinal fiber. The odontoblasts are intimately con- 

 nected with each other by means of fine, short teeth, which the lateral processes 

 of all dentinal cells form. 



S. J. A. Salter|| says: "A very pale, ill-defined, areolar tissue, pervaded 

 by numerous round and oval cells or nuclei, occupies the spaces between the 

 vessels and nerves. The cellular bodies toward the surface are enlarged and 

 assume the form of columnar epithelium. From their extremities project 

 minute tubular prolongations, which constitute the animal basis of the dentinal 

 tube-wall." 



* ' Beitriige zur Histol. uncl Pathol. d. Zalmpulpe," Breslau, 1871. 



t ' System of Deutal Surgery," 1873. 



t ' The Pathology of the Teeth," Philadelphia, 1872. 



'Manual of Histology," by S. Strieker, New- York, 1872. 



|| ' Dental Pathology ami Surgery," New- York, 1875. 



