ON DENTAL EXOSTOSIS. 41 



Having thus given a brief sketch of the structure 

 fully formed in exostosis of the fang, I will now 

 proceed to describe the manner of its formation, as 

 far as ray investigations have hitherto advanced. 



The periosteum being the seat of the disease, it 

 may be as well just to call to mind the tissues 

 entering into its composition, since we shall then be 

 the better able to judge of any departure from its 

 natural healthy condition. The principal element 

 is the common white fibrous tissue, well known 

 by its beautiful .wavy tresses shown under the 

 microscope, and in this clusters of fat globules are 

 to be found, whilst traversing it are seen minute 

 bloodvessels and nervous filaments. The space thus 

 occupied, intervening between the fang and surface 

 of the alveoli is extremely narrow, and, were exos- 

 tosis to be confined to the natural periosteum, its 

 extent would be always extremely limited. How 

 then does it attain so large a size as in the speci- 

 mens which are before you? 



Since stumps, as I have stated, are so commonly 

 the seat of exostosis, and, from the facility with 

 which such specimens can be procured, I have made 

 my observations principally upon them and upon 

 the exostosis of teeth afiected with caries. Teeth 

 affected with exostosis, but otherwise apparently 

 sound, being of rare occurrence, I have not been 

 able to verify my results upon them ; but since the 

 deposit of cementum presents exactly the same cha- 

 racter, both to the naked eye and microscopically, 



