DEVELOPMENT OF THE TEETH. 109 



connexions with the rest of the economy, the teeth were prior to 

 the microscopical researches above detailed considered analogous 

 to the hair, nails, and feathers of mammiferae and birds, and to 

 the shells of molluscae. It cannot be said that the teeih are 

 absolutely inorganized, that they are mere concretions of an 

 effused fluid, since there is no part appertaining to living beings, 

 entirely destitute of life ; but in the hard structure of the teeth, 

 no anatomist has yet demonstrated either vessels or nerves, though 

 there are practical dentists, who assert that they have seen blood 

 issu from the bony part of the teeth, in some of their operations.* 



* Hunter denies positively the existence of any vessels passing between the. 

 pulp and bone of the teeth, as he was not able to render them manifest by injec- 

 tion, as the coloring matter does not pass into them when animals are fed upon 

 madder, except in the forming state, and as they do not share in the general soft- 

 ening of the bones, in rickets and malacosteum. Blake believed that these 

 vessels did exist, but were difficult to demonstrate, like those that we know to 

 pass in the eye from the capsule of the crystalline lens, to the lens itself; Beclard, 

 that there were no vessels in the bone of the teeth, continuous with those of the 

 pulp, but that the former received continually from the latter a nourishing liquid 

 which penetrated it by imbibition, and that it was situated in regard to the pulp, 

 as the hair and nails to the vascular part of the skin. But the morbid altera- 

 tions which take place in the body of the teeth, the softening and exostosis seen 

 frequently at their roots, and the fusion of the latter occasionally to the bottom 

 of the alveoli, render their vascularity highly probable. 



The fang of a perfectly developed tooth, is covered closely by a membrane, 

 called its periosteum, which is continuous with the periosteum of the socket, and 

 is on all hands admitted to be vascular ; the internal cavity is also lined by a 

 highly nervous and vascular membrane. Both of these are intimately con- 

 nected with the bony structure of the tooth, and require a little force to separate 

 them. This connection Mr. T. Bell believes to be made by vessels and probably 

 nerves, which pass between them and the bone. Though no artificial injection? 

 has been made of the teeth, this writer has seen them tinged with a bright yel- 

 low in a young woman who died of jaundice ; and where death has taken place 

 from hanging or drowning, when there is usually a congestion of the capillary 

 system, " he has found the osseous part colored with a dull deep red which could 

 not possibly take place if they were devoid of a vascular system ; in both 

 instances the enamel remained wholly free from discoloration." I have observed 

 the same thing in the teeth of subjects who have died of cholera. The existence 

 of nerves in the bony part of the teeth Bell considers manifested by the facts 

 common'y observed by dentists ; in filing the teeth no pain whatever is produced 

 till the. enamel is removed ; but the instant the file begins to act upon the bone, 

 the sensation is exceedingly acute : and when the gums, alveoli and periosteal 

 lining membrane, have receded from the teeth so as to leave the bony part bare, 

 it is exquisitely sensitive when touched with any hard instrument. 



He admits likewise the existence of absorbents in the bony part of the teeth, 

 for in a tooth in which inflammation had existed for a considerable time, he 

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