THE TEETH. 47 



canals, and have precisely the same aspect as the dentine, 

 of which they are obviously nothing but portions ; whilst in 

 the latter, such dentinal globules, as I will term thern, are not 

 always distinct. This is especially true of the smallest spaces, 

 which, on account of their notched form, and their communica- 

 tions with dentinal canals, might be taken for osseous lacuna, 

 and indeed have been so regarded ; yet, at least in the crown, 

 it is almost always easy to recognise their identity with the 

 larger spaces. Greater difficulty is met with upon the fang, 

 where small interglobular spaces and globules form a zone, 

 (the granular layer of Tomes) which often appears like a 

 layer of small osseous lacunse or of simple granules. I have 

 but rarely observed actual lacunae in normal dentine; they were, 

 when present, invariably situated at the boundary of the cement 

 (fig. 185) ; on the other hand, interglobular spaces and 

 dentinal globules are to be met with in the interior of the 

 dentine of the root, and with especial distinctness on the walls 

 of the pulp cavity, in which latter locality the globules often 

 give rise to irregularities visible to the naked eye, or even to 

 a botryoidal appearance. The interglobular spaces whose 

 presence is normal in developing teeth, contain during life, not 

 fluid, as might at first sight be expected, but a soft substance 

 resembling tooth cartilage and possessing a canaliculated 

 structure, like the dentine itself. It is remarkable that this 

 substance offers a greater resistance to long maceration in 

 hydrochloric acid than the matrix of the actually ossified tooth 

 and therefore, like the dentinal canals, it may be completely 

 isolated. In sections, this interglobular substance usually dries 

 up in such a manner that a cavity is produced, into which air 

 penetrates ; it is properly only in reference to these, that inter- 

 globular spaces can be spoken of. Many teeth, indeed, exhibit 

 no interglobular substance, but they occasionally present the out- 

 lines of dentinal globules, in the form of delicate arched lines. 



Dentine containing Haversian canals, the so called ' vaso- 

 dentine' of Owen, which exists in many animals, is rarely found 

 in man, and I am only acquainted with one case, observed by 

 Tomes, (1. c, p. 225), in which the vascular canals were 

 numerous ; on the other hand, in the dentine, with irregular 

 tubuli which is formed in obliteration of the pulp cavity, we 

 occasionally meet with scattered Haversian canals and rounded 





