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March 13, 1856. 

 Sir BENJAMIN C. BRODIE, Bart., V.P., in the Chair. 



The following communications were read : 



I. " On the presence of fibrils of soft tissue in the Dentinal 

 Tubes." By JOHN TOMES, Esq., F.R.S. Received Fe- 

 bruary 21, 1856. 



(Abstract.) 



Referring to the structural characters of dentine, and to the pre- 

 vailing belief that the dentinal tubes in the normal condition contain 

 fluid, the author goes on to show that the recognized histological 

 characters fail to account for the high degree of sensibility exhibited 

 by the dentine when diseased, or when suddenly exposed by the 

 removal of the enamel. 



It is found, moreover, that the dentine is not uniformly sensitive 

 throughout, but possesses a much higher degree of sensibility at the 

 peripheral distribution of the dentinal tubes than deeper in the sub- 

 stance of the tooth ; and it is urged that these facts cannot be 

 accounted for by the presence of a fluid in the dentinal tubes, nor 

 by supposing that the hard unyielding dentine is intrinsically en- 

 dowed with sensation. This view of the matter is borne out by the 

 fact, that all sensibility is at once lost if the pulp of the tooth be 

 destroyed. 



Finding that the dentine owed its sensibility to the presence of 

 the dentinal pulp, and knowing that the tubes have open extremities 

 in contact with the pulp, the author was induced to examine care- 

 fully the contents of the tubes. The investigation resulted in disco- 

 vering that the dentinal tubes, instead of containing fluid only, give 

 passage to fibrils of soft tissue, which pass from the pulp into the 

 tubes where these open upon the surface of the pulp-cavity, and from 

 thence may be traced into the branches. The fibrils may be demon- 

 strated by fracturing a perfectly fresh tooth, and then with a sharp 

 knife taking very thin sections from the dentine near the edge of 



