46 



SPECIAL HISTOLOGY. 



Fig. 188. 



lamellse (Owen), indications of which may be found also in 

 fresh human teeth and in the dental cartilage. 



Upon the crown, the dentinal canals not unfrequently pass 

 for some distance into the enamel, and expand here and there, 

 into larger cavities (fig. 191), which should perhaps rather be 

 regarded as pathological. Similar not quite normal formations 

 are the interglobular spaces in the dentine itself (fig. 188). 



Czermak has con- 

 ferred this name 

 upon certain very 

 irregular cavities, 

 bounded by globular 

 processes of the den- 

 y tine, which are, it may 

 be said, never entirely 

 absent in the teeth. 

 In the crown they 

 are found most fre- 

 quently in the neigh- 

 bourhood of the enamel, and often form a thin curved layer, ex- 

 tending along its whole inner surface, which, upon close exami- 

 nation, is seen to be composed of a multitude of thin layers, re- 

 ceiving the ends of the contour lines (fig. 187). They also occur, 

 however, more internally, but always in longitudinal sections, in 

 lines which correspond with the contour lines. The spaces are 

 sometimes very wide, intersecting or interrupting in their 

 course many dentinal canals; sometimes they are very small, 

 so that only a few canals are touched by them. In the former 

 case, their limits are formed by distinct globular projections 

 of 0002 — 0012"' and more, which are pierced by dentinal 



Fig. 188. A morsel of dentine with dentinal globules and interglobular spaces 

 filled with air between them, x 350. 



long before drawn attention to these peculiar striae. In his admirable memoir, pub- 

 lished in Midler's Archiv, for 1837, he says, p. 507, "In the incisor teeth of the 

 horse, also, many less transparent striae running parallel with the cavitas pulpee may 

 be seen, like the annual rings in the trunk of a tree. They proceeded in this case, 

 however, not merely from certain parallel flexures of the tubes, but especially from 

 similar calcareous cells, which had accumulated in one zone for the greatest part of 

 the length of the tooth. Tab. xxii, fig. 3." See also his explanation of the zones 

 in the Elephant's tooth, at pp. 510-11. — Eds.] 



