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 I 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 iste fibre equaliter quam- 
cunque regionem versus se diffundunt, attamen parietes laterales 
versus directiolongitudinalis preevalet, dum fibree sinuosis flexibus 
eequalique modo se invicem contingentes ibique ubi concave 
apparent lacunas inter se relinquentes, ab apice coronali radicem 
versus ubicunque procedunt. Non nisi extremi earum fines 
tune molles sunt ceterze autem partes brevissimo tempore in- 
durescunt. . . . . ‘Substantize 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. .. .. Convexee fibrarum dentalium 
flexuree, que juxta latitudinis dimensionem crescunt, dum ab 
externa regione internam versus procedunt, sibi Invicem appo- 
site continuos canaliculos effingunt, qui ad substantiz dentalis 
peripheriam exorsi multis parvis anfractibus ad pulpam dentalem 
cavumque ipsius tendunt, ibique aperti finiuntur, novis ibi, 
quamdiu substantiz dentalis formatio durat, fibris dentalibus 
aggregandis inservientes.” (Raschkow, Meletemata circa Mam- 
malium dentium evolutionem. 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 supplymg the material for the purpose) ; 
that these fibres then coalesce, leaving, however, spaces be- 
tween them which are the dental tubes. Since, according 
to Miller, 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. 
