72 A MANUAL OF DENTAL ANATOMY. 



fibrils may be propagated to the pulp, and irritation of the 

 pulp set up without any real exposure of the latter. 



With reference to the probabilities of actual nerve fibres 

 entering the dentinal tubes, it must be remembered that, in 

 those tissues which are naturally so thin as to present 

 great facilities for examination, nerves of a degree of fine- 

 ness unknown elsewhere have been demonstrated ; in other 

 words, the easier the tissue is to investigate, the finer the 

 nerves which have been seen in it, while dentine is among 1 

 the most difficult substances conceivable for the demonstra- 

 tion of fine nerve fibrils, if such exist in it. 



Inter globular Spaces. In the layer of dentine which 

 underlies the cement an immense number of these spaces, 

 exist, giving to the tissue as seen under a low power an 

 appearance of granularity. On this account my father gave 



to this the name of the " granular layer " of dentine ; on 

 account of the far greater abundance of the spaces in that 

 situation it is far more marked beneath the cement than 

 beneath the enamel, and many of the dentinal tubes end in 

 these spaces. 



Although the name " interglobular spaces " is strictly ap- 

 plicable to the structures constituting the granular layer 

 of dentine, it was not to these that it was first applied. 

 When a dried section of dentine is examined, dark irregular 



( J ) Dentinal tubes terminating in the spaces of the granular layer. 



