XXXii INTRODUCTION. 



subject are as follows : after observing that the blood-vessels of 

 true bone are confined to the medullary canals, and that the 

 presence or absence of blood-vessels in a tissue occasions no es- 

 sential difference in its mode of growth ; he proceeds to classify teeth 

 with bones in an order of tissues, characterized by the parietes of their 

 primordial cells becoming confluent either with each other, or with the 

 intercellular substance ( 1 ) . 



Dr. Schwann identifies the pulp-granules of Purkinje with his 

 nucleated cells, and asks, " In what relation does the dentine stand 

 to the cells?" He then proceeds to say, " I must confess, at the 

 outset, that I am unable to answer this question with certainty, and 

 that my observations are not mature. Purkinje and Raschkow describe 

 the formation of the dentine as follows : — " Primordio substantia den- 

 talis e fibris multifariam curvatis convexis lateribus sese contingentibus 

 ibique inter se concrescentibus composita apparet. — In ipso apice istse 

 fibrse sequaliter quamcunque regionem versus se diffundunt, attamen 

 parietes laterales versus directio longitudinalis preevalet, dum fibrse 

 sinuosis flexibus sequalique modo se invicem contingentes ibique ubi 

 concavse apparent lacunas inter se relinquentes, ab apice coronali 

 radicem versus ubicunque procedunt. Nonnisi extremi earum fines 

 tunc molles sunt cseterse autem partes brevissimo tempore indurescunt 

 . .Postquam. . , .fibrarum dentalium stratum depositum est, idem 

 processus continuo ab externa regione internam versus progreditur, 

 germinis dentalis parenchymate materiam suppeditante .... Convexse 

 fibrarum dentalium flexurse, quae juxta latitudinis dimensionem cres- 

 cunt, dum ab externa regione internam versus procedunt, sibi 



(1) Microskopische Untersuchungen iiber die Uebereinstimmung in der Struktur imd dem 

 Wachsthum der Thiere und Pflanzen. 8vo. 1839, p. 117. 



