OF LIVING ELEPHANTS. J 97 



substance called osseous, by the inner membrane of the capsule, in 

 the form of small fibres or rather of small crystals, all perpendicular 

 to this surface, and forming there, at first, a sort of fine velvet. ^Vhen 

 •sve open a capsule of a germ of a tooth, we find the small molecules of 

 the future enamel, still very slightly adhering to the internal surface 

 of this capsule, and very easily detached from it. A part floats evert 

 in a liquor interposed between the capsule and the germ. I have 

 not seen the small vesicles adhering to the capsule, from which Heris- 

 sant states the substance to proceed, which must on drying become 

 the enamel; The opinion of Hunter that the enamel is but the sedi- 

 ment of the liquid interposed between the tooth and its capsule, is in- 

 accurate, inasmuch as he leaves too much out of view the capsular 

 membrane, from whence the molecules of the enamel really proceed; 

 but it is very true, that these molecules are at first between this mem? 

 brane and the tooth before it becomes attached to the latter. With, 

 respect to the other opinion, which makes the enamel to issue, as it 

 were, by efflorescence, from the pores of the osseous substance, though 

 it has been received by many anatomists, it has tiot the slightest 

 foundation in observation. 



But let us return to the teeth. 



A thick layer of enamel investing, then, the crown on every side, fills 

 a part of the intervals, which the transverse lamellae and their dentuli 

 (dentelures) had at first left between them. 



The rest of these intervals is entirely filled by a third substance, 

 called by M. Tenon the bony cortex (cortical osseux), because it enve- 

 lopes all the others, and it resembles an ordinaiy bone in its chemical 

 nature and its hardness^ stUl more than the two other parts of the tooth. 

 M.. Home also calls it bone, whilst he gives the name of ivory to the 

 substance ordinarily called osseous. M. Blake gives this cortical part 

 the name of crusta petrosa. 



Its production has something in it verj' remarkable. M. Tenon 

 considered that it came from the ossification of the inner lamella of the 

 capsule, when this capsule had produced the enamel. M. Blake thinks 

 that this lamella, after having given the enamel by one of its surfaces, 

 yields the cortex by its opposite surface. M. Home has not expressed 

 himself at all clearly on this subject. 



For my part, I have satisfied myself that the cortical part is produced 

 by the same lamella and the same surface, which produced the enamel ; 

 the proof is, that this lamella remains outside the cortical part, as it 

 was at first outside the enamel, and that it remains there soft and free 

 as long as this cortical part allows it room. It only changes as to its 

 tissue ; as long as it yielded only enamel, it was soft and transparent; in 

 order to yield the cortical part, it becomes thick, spongy, opaque and 

 reddish. The cortical part which is formed is not in close threads, 

 but as it were in small drops, which might have been thrown out by 

 mere chance. 



The membranous productions of the capsule of the tooth tend to- 

 wards the summit and sides, according as the cortical part which they 

 deposit on the enamel fills all the empty space which remained between 

 the different lamellse of the tooth. The summits of these lamellae are 

 covered with the cortical part, as well as the remainder, so long ae 



