THE ATTACHMENT OF TEETH. 207 



Attachment by Anchylosis. In both the socketed and 

 the membranous manners of attachment an organised, more 

 or less vascular membrane, intervenes between the tooth and 

 the jaw-bone ; in the method now under consideration there 

 is no such intervening membrane, but the calcined tooth 

 substance and the bone are in actual continuity, so that it 

 is often difficult to discern with the naked eye the line of 

 junction. 



The teeth may be only slightly held, so that they break 

 off under the application of only a moderate degree of force, 

 or they may be so intimately bound to the bone that a 

 portion of the latter will usually be torn away with the 

 tooth. 



A very perfect example of attachment by anchylosis is 

 afforded by the fixed teeth of the Pike, of which the central 

 cone is composed of osteodentine. The method by which the 

 entire fusion of this tissue with the bone beneath it takes 

 place has already been alluded to, the similarity of its 

 method of calcification with that of bone rendering the 

 fusion easy and complete. 



And in certain extinct fish, whose nearest ally is the now 

 anomalous Australian shark, the Cestracion philippi, the 

 lower part of the tooth is composed of osteodentine, which 

 so closely resembles bone itself that it is impossible to say 

 at which point the bone may be said to commence and the 

 tooth to end ; but even where this intimate resemblance in 

 histological character does not exist, there is often to be 

 found more or less blending of the basal dentine with the 

 bone beneath it, so that there is even here a sort of transi- 

 tional region. 



From the accounts which pass current in most text books 

 it would be supposed that the process of attachment by 

 anchylosis is a very simple matter, the base of the dentine 

 papilla, or the dental capsule, by its calcification cementing 

 the tooth on to a surface of the jaw-bone already formed. 



