206 MICROSCOPIC ANATOMY OF THE TEETH 



the dentinal tube, it appears that this must necessarily be 

 an extension of the cell membrane of the odontoblast. 



Each odontoblast is furnished with this protoplasmic 

 prolongation into the dentinal tube and with a delicate 

 process at its pulp extremity which passes into the connective 

 tissue ; this process is, however, often difficult to detect. 

 A lateral process of the cell has also been described con- 

 necting the cells to one another at the dentine margin. 

 Professor Paul describes these lateral processes as ' collars ' 

 consisting ' of a delicate network of pulp fibrils ', and does 

 not consider them to be any portion of the cell itself (23). 

 He says they are only visible in developing teeth and entirely 



FIG. 122. Human adult premolar showing transverse 

 processes ot odontoblasts. ( x 75.) 



absent in adult pulps. In fig. 122, however, a photograph 

 from a fully formed functional premolar tooth shows 

 lateral processes connecting the odontoblasts very clearly, 

 and these certainly appear to form portions of the cell. 

 This was photographed from a specimen of the author's 

 stained with iron and tannin, and, the 'same appearance is 

 to be seen in. many sections. 



In fig. 123 a curious condition of the dentine is represented. 

 The photograph was from a carious tooth, and the dentinal 

 tubes are seen to be connected to a transverse tube with 

 which they form anastomoses ; the tubes are filled with 

 micro-organisms. This same condition was seen in a healthy 

 developing tooth in several parts of the circumference near 

 the pulp margin. It is very difficult to account for this 

 condition. A comparison of figs. 122 and 123 might suggest 



