42 



SPECIAL HISTOLOGY. 



dry sections appear milk-white, and if not very thin, are quite 

 unfit for microscopic investigation, unless the air has been pre- 

 viously expelled from the canals by any clear and not viscid 

 fluid. 



Fig. 185. 



Fig. 186. 



The dentinal canals present 

 certain constant peculiarities in 

 their course which may be best 

 gathered from figs. 185 and 187; 

 it is not straight but wavy, and in 

 addition, they present numerous 

 ramifications and anastomoses. 

 Each canal describes, in general, 

 two or three large curvatures, and 

 a very great number (as many as 

 200 in Y" , according to Retzius) 

 of small curvatures, which are 

 sometimes more or less strongly 

 marked and occasionally have 

 even the appearance of actual 



Fig. 185. Dentinal tubules from the root, 

 x 350: a, internal surface of the dentine, 

 with scattered canals ; b, their divisions ; c, 

 terminations with loops ; d, granular layer, 

 consisting of small dentinal globules at the 

 boundary of the dentine; e, bone lacuna, 

 one anastomosing* with dentinal canals. 

 From Man. 



Fig. 186. Transverse section through the 

 dentinal canals of the root, a, in order to 

 exhibit their excessively numerous anasto- 

 moses, x 350. From Man. 



