30G DEVELOPMENT. 



In the formation of a single fang, the activity of the reproductive 

 process becomes enfeebled at the circumference, and is progressively 

 contracted within narrower limits in relation to a single centre, 

 until it ceases at the completion of the apex of the fang ; which, 

 though for a long time perforated for the admission of the vessels 

 and nerves to the interior of the tooth, is, in many cases, finally 

 closed by the ossification of the remaining part of the capsule. 



When a tooth is destined to be implanted by two or more 

 fangs, the reproduction of the pulp is restricted to two or more parts 

 of the base of the coronal portion, around the centre of which 

 parts the sphere of its reproductive activity is progressively con- 

 tracted. The intervening parts of the base of the coronal pulp 

 adhere to the capsule, which is simultaneously calcified with them, 

 covering those parts of the base of the crown of the tooth with 

 a layer of cement. The ossification of the surrounding jaw being 

 governed by the changes in the soft, but highly organized dental 

 matrix, fills up the spaces unoccupied by the contracted and divided 

 pulp, and affords, by its periosteum, a surface for the adhesion of 

 the cement or ossified capsule covering the completed part of the 

 tooth(l). 



huge extinct animal called Basilosaurus by Dr. Harlan, and have advocated the claims of 

 the diminutive Amphitherium and Phascolotherium of the oolite slate of Stonesfield, to be 

 admitted into the same high class, against the objections raised by Dr. de Blainville. See 

 Comptes Rendus de I'Acad. des Sciences, Oct. 22, 1838. The bifid base of the teeth of certain 

 Sharks not being implanted in a socket, forms no true exception to the rule enunciated in the 

 text. Geological Transactions, 2nd Series, vol. vi. p. 66. 



(1) Cuvier ascribes the formation of the fangs of teeth partly to phenomena which are 

 real, but merely concomitant, partly to conditions of the pulp which have no existence. 

 He observes : " La production des racines est due a ce que le noyau pulpeux n'adhere pas 

 au fojid de la capsule, par la totalite de sa base, mais seulement par certains endroits, 

 qui peuvent etre des lors conside'res corame des pedicules tres courts. Les lames osseuses 

 arrivees au has du noyau, se glissent entre ces pedicules, et les entourent eux-memes d'une 

 enceinte tubuleuse qui, s'alongeant toujours, force aussi les pedicules pulpeux a s'alonger, 

 et produit ainsi les racines." Legons d'Anat. Comp. ed. 1836, tom. iv. p. 215. 



If the molar of an Ox be examined at the period when the outer crust of the crown 

 is completed, and the fangs have begun to be formed, the capsule will be found adhering 

 to the base of the pulp at their interspaces as well as to their circumference. A vertical 

 slice of such a molar, when it is fully developed, exaimned with a magnifying power of 

 300 linear dimensions, displays a layer of cement covering the concave interspaces of the 

 base of the fangs; this layer is as distinct in character from the dentine as that which 



