102 IVORY OF THE TEETH. 



What relation then does the ivory bear to the cells ? I 

 must at once avow that I cannot give a positive reply to 

 this question, and that T only communicate the following im- 

 perfect investigation for the sake of presenting a connected 

 view of my subject. The formation of the dental substance 

 is described by Purkinje and Raschkow as follows : " Primordio 

 substantia dentalis e fibris multifariam curvatis convexis late- 

 ribus sese contingentibus ibique inter se concrescentibus com- 



posita apparet In ipso apice istas fibras pequaliter quam- 



cunqne regionem versus se diffundunt, attamen parietes laterales 

 versus directio Ion gitudinalis prasvalet, dum fibras sinuosis flexibus 

 a^qualique modo se invicem contingentes ibique ubi concavas 

 apparent lacunas inter se relinquentes, ab apice coronali radicem 

 versus ubicunque procedunt. Non nisi extremi earum fines 

 tunc molles sunt ceteras autem partes brevissimo tempore in- 



durescunt Substantias dentalis formationis secundum 



crassitudinem processus pari modo ac primo ejus ortu cogi- 



tandus est. Postquam fibrarum dentalium stratum 



depositum est, idem processus continuo ab externa regione 

 internam versus progreditur, germinis dentalis parenchymate 

 materiam suppeditante. .... Convexas fibrarum dentalium 

 flexuras, quae juxta latitudinis dimensionem crescunt, dum ab 

 externa regione internam versus procedunt, sibi invicem appo- 

 sitas continuos canaliculos effingunt, qui ad substantias dentalis 

 peripheriam exorsi multis parvis anfractibus ad pulpam dentalem 

 cavumque ipsius tendunt, ibique aperti finiuntur, novis ibi, 

 quamdiu substantias dentalis formatio durat, fibris dentalibus 

 aggregandis inservientes." (Raschkow, Meletemata circa Mam- 

 malium dentium evohdionem. Vratislav. 1835, p. 6.) 



I must admit that I do not clearly understand some of this 

 description, but if I rightly comprehend it, the dental substance 

 originates from fibres which are formed in strata around the 

 pulp (the latter supplying the material for the purpose) ; 

 that these fibres then coalesce, leaving, however, spaces be- 

 tween them which are the dental tubes. Since, according 

 to Muller, the tubes are furnished with special walls, we can 

 no longer regard them as mere spaces between the fibres. 

 His observation, however, does not affect the explanation of 

 the formation of the firm substance. 



