INTRODUCTION. XXXUI 



invicem appositse continuos canaliculos effingunt, qui ad substantise 

 dentalis peripheriam exorsi multis parvis anfractibus ad pulpam 

 dentalem cavumque ipsius tendunt, ibique aperti finiuntur, novis ibi, 

 quamdiu substantise dentalis formatio durat, fibris dentalibus aggre- 

 gandis inservientes." — Raschkow, 1. c. p. 6. 



" I must confess," Dr. Schwann proceeds to say, " that there 

 is much obscurity in this description. If I rightly understand it, the 

 dentine consists of fibres, formed layer- wise out of material afforded 

 by the pulp, which become confluent with each other but leave inter- 

 spaces which are the dentinal tubes. But these tubes cannot be 

 mere interspaces between fibres, since Miiller has proved them to pos- 

 sess distinct parietes. . .If a young tooth be removed from its capsule 

 and steeped for one day in not too much diluted muriatic acid, the 

 animal basis of the dentine, which, at the first removal of the earth, 

 was of cartilaginous hardness, becomes quite soft, so that one can 

 only detach small pieces from it by the forceps. If this pultaceous 

 mass be examined, it will be seen to consist of fibres, which can be 

 separated from one another. These fibres are too thick to be merely 

 the walls of the canals ; they constitute the whole substance. Neither 

 can they be a mere artificial product, since the acid penetrating the 

 canals first dissolves the immediately contiguous substance, and then 

 the intertubular substance remains as a fibre ; besides, they are too 

 regular and smooth. It appears, moreover, that the dentine is com- 

 posed of these reciprocally united fibres, since they are identical with 

 the fibres which, according to Purkinje and Raschkow, form by their 

 confluence the dentinal cartilage ; and this confluence of the fibres 

 is not so complete but that they can be again artificially separated. 

 The fibres in the human teeth run in the same direction as the canals. 

 I could not discern the canals in their interspaces. The peripheral 



