vm IXTRODUCTIOIS'. 



of a cellular and tubular basis of animal matter, con- 

 taining earthy particles, a fluid, and a vascular pulp. 



'^In general, the earth is present in such quantity 

 as to render the tooth harder than bone, in which case 

 the animal basis is gelatinous, as in other hard parts 

 where a great proportion of earth is combined with 

 animal matter. In a very few instances, among the 

 vertebrate animals, the hardening material exists in a 

 much smaller proportion, and the animal basis is albu- 

 minous ; the teeth here agree, in both chemical and 

 physical qualities, with bone. 



"I propose to call the substance which forms the 

 main part of all teeth dentine.* The second tissue, 

 whicli is the most exterior in situation, is the cement. 

 The third tissue, wliich, when present, is situated be- 

 tween the dentine and cement, is the enamel. 



"Dentine consists of an organized animal basis and 

 of earthy particles. The basis is disposed in the form 



*In a reference note in the Introduction to liis "Odontogra- 

 phy," Prof. Owen says: "Besides the advantag-e of a substan- 

 tive for an unquestionably distinct tissue under all its modifica- 

 tions in tlie animal kingdom, the term dentine may be inflected 

 adjectively, and the properties of this tissue described without 

 the necessity of periphrasis. Thus we may.speak of the ' denti- 

 Dal' pulp, 'dentinal' tubes or cells, as distinct from the corre- 

 sponding properties of the other constituents of a tooth. The 

 term 'dental' will retain its ordinary sense, as relating to the 

 entire tooth or system of teeth." 



Wote.— The particular paraprraph to which the aVove note re- 

 fers is from Prof. Owen's " Odontography." " The Anatomy of 

 Vertebrates " having been written about twenty-five years sub- 

 sequent to the "Odontography," and therefore reflecting the 

 Professor's riper thon2:hts, the extracts made from, it were sub- 

 Btituted for very similar matter in the " Odontography." 



