Vlll INTRODUCTION. 



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, 

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

 The third tissue, which, 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 his " Odontogra- 

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

 tive for an unquestionably distinct tissue under all its modifica- 

 tions in the 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- 

 nal' pulp, 'dentinaT 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." 



Note. The particular paragraph to which the above note re- 

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

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

 sequent to the " Odontoorraphy," and therefore reflecting the 

 Professor's riper thoughts, the extracts made from it were sub- 

 stituted for very similar matter in the " Odontography." 



