THE TEETH. 629 



minated the canalicules. But an attentive examination shows that, although 

 the granulations are continuous with the terminal extremities of the canal- 

 icules, we cannot compare them to osseous corpuscles, but that they should 

 rather be regarded as minute pits sunk in the thickness of the ivory, at its 

 exterior limit, to aid the communications between the tubules which permeate 

 this tissue. . . . During life the dentinal canalicules inclose a transparent, 

 colorless fluid, containing, according to Hannover, calcareous matter in solu- 

 tion. . . . For a long time there has been attributed to the ivory a sensi- 

 bility of its own an opinion still held by many, even in the admitted 

 absence of nerve-branches, and supported by the fact that the teeth vividly 

 perceive the impressions of temperature, of acids, etc., and distinguish the 

 physical qualities of bodies submitted to their contact, such as grains of sand 

 and hairs. This tactile sensibility, in fact, does not belong to the ivory, and 

 must be attributed to the extreme facility with which this substance receives 

 the least vibrations, the slightest disturbances which are given to it by 

 external influences, and transmits them to the pulp, whose tissue, extremely 

 rich in nerves, fills exactly its solid shell, and thus perceives the smallest 

 impressions communicated to it." Of the enamel he asserts: " The layer of 

 enamel surrounding the crown is composed of an infinite number of rods, 

 prismatic by reciprocal pressure, whose length is just equal to the thickness 

 of the tissue at the corresponding point, and intimately united without the 

 interposition of any other substance." 



DENTINE AND ENAMEL OF DECIDUOUS TEETH. BY FRANK ABBOTT, M. D.* 



While engaged in the study of the process of dissolution of temporary 

 teeth, I availed myself of the method of examination of enamel as first 

 described by Bodecker. Specimens of deciduous teeth, if prepared in this 

 manner, exhibit, as the most striking feature, a considerably smaller amount 

 of basis-substance than adult teeth. As a consequence, the dentinal canal- 

 iculi are much wider, and the dentinal fibers larger ; thus, the possibility of 

 seeing the minutest relations between dentinal fibers and basis-substance is 

 greatly facilitated. 



I can add nothing to what Bodecker has described in minutest details in 

 reference to the structure of dentine. I could easily see the dentinal fibers 

 (which, upon being stained with carmine, assume a dark red color) running 

 through the canaliculi up to their bifurcations, close to the enamel. I could 

 trace the lateral conical offshoots of the dentinal fibers to the point where 

 they enter the basis-substance of the dentine. That the basis-substance holds 

 a delicate reticulum of living matter I am perfectly satisfied, and I base my 

 opinion upon my researches on caries of the teeth. 



As to enamel, I have never seen the minute relations marked so plainly in 

 permanent as I find them in the temporary teeth. Here the enamel-rods are 

 narrower, and the interstices between them wider, than in permanent or adult 

 teeth. A power of 500 diameters of the microscope is sufficient to show 

 plainly relations visible in permanent teeth with very much higher powers 

 only. As a striking feature in deciduous teeth, I often found a direct connec- 

 tion of the fibers of the dentine with those of the enamel. Thus, the width of 

 an enamel-rod is in full correspondence with the width of the fields of basis- 



* Abstract from the author's paper, " The Minute Anatomy of Dentine and Enamel." The 

 Dental Cosmos, Philadelphia, 1880. 



