and maintained an equable secretion of the dentine 

 throughout the lifetime of the auimal. This idea of 

 the pulp's function has predominated in the minds of 

 most subsequent writers on the development of the 

 tectii. * ^ '' * 



" Three formative organs are developed for the three 

 principal or normal dental tissues, the ' dentinal-pulp/ 

 or pulp proper, for the dentine, the 'capsule' for the 

 cement, and the ^enamel-pulp' for the enamel. The 

 essential fundamental structure of each formative 

 organ is cellular, but the cells differ m each organ, 

 and derive their specific characters from the properties 

 and metamorphoses of their nucleus, upon which the 

 specific microscopical characters of the resulting calci- 

 fied substances depend. 



"In the cells of the dentinal-pulp the nucleus fills 

 the parent cell with a progeny of nucleoli before the 

 w^ork of calcification begins. In the enamel-pulp the 

 nucleus of the cell disappears, like the cytoblast of the 

 embryo plant m the formation of most vegetable tis- 

 sues. In the cells of the capsule the nucleus neither 

 perishes nor propagates, but retains its individuahty, 

 and o-ives oricrin to the mos^ characteristic feature of 

 the cement, viz., the radiated cells. 



"The primordial material of each constituent of the 

 tooth-matrix is derived from the blood, and special 

 a,rraugements of the blood-vessels preexist to the devel- 

 opment and growth of the constituent substances. A 

 pencil of capillaries is directed to a particular spot in 

 the primitive dentiparous groove, and terminates there 

 by a looped network, from which spot a group of nu- 

 cleated cells begins to arise in the form of a papilla. 



-ft-' 



"The primary dentinal papilla and its capsule rap- 



