14 DR. BEALE, ON THE TISSUES, 



tooth pulp, in other words, an intercellular substance."* 

 Now, Mr. Tomes has shown that the dentinal tubes are occu- 

 pied with a soft^ solid structure which may be seen projecting 

 in the form of solid processes from the broken ends of the 

 dentinal tubes. The truth of these observations has, however, 

 been doubted by several observers. Dr. Beale has been able 

 to verify jMr. Tomes' statements as to the dentinal tubes 

 being occupied with this soft structure, and sent round a pre- 

 paration in Avhich this material had been coloured red with 

 carmine, and was most clearly demonstrated. The dentinal 

 '' tubes " of a living tooth, Dr. Beale says, are never empty ; 

 indeed they are not tubes, nor are they canals for the trans- 

 mission of nutrient substances dissolved in fluid_, but they 

 contain a soft solid substance, the central portion of which is 

 in a state of active vitality. 



If for a moment one of the soft nuclear fibres of tendon 

 was supposed to be surrounded with a matrix impregnated 

 with calcareous matter a good idea would be formed of the 

 structure of the " dentinal tube " and its contents. 



The wall of the tube with the matter between the tubes 

 correspond to the " wall " of an ordinary cell, or to this and 

 the intercellular substance [formed material), and the con- 

 tents of the tube to the granular cell contents with the nuclei 

 [germinal matter) . If the tissue of the pulp just beneath the 

 surface of the dentine be examined, a number of oval masses 

 of germinal matter coloured intensely red by carmine are 

 observed. These are nearly equidistant and separated from 

 each other by a certain quantity of material which is only 

 very faintly coloured, and in cases when the solution was not 

 very strong it remained colourless. This colourless matrix is 

 continuous Mith the intertubular dentinal tissue, while the 

 intensely red germinal matter, or rather a prolongation from it 

 extends into the dentinal tubes. The germinal matter with 

 a thin layer of soft and imperfect formed material is easil}^ 

 detached from the formed material by which it is surrounded, 

 and its continuity with the dentinal tubes may often be torn 

 away. The whole then appears as an oval mass (cell) with a 

 prolongation as it were into the dentinal tube. 



The general description given of the manner in which these 

 dentinal tubes ojjen upon the walls of the pulp cavity is cer- 

 tainly true, but it is true only of the dry tooth. In the living 

 tooth a prolongation from one of the '^ cells " on the surface 

 of the pulp is prolonged into each tube. The tubes cannot, 

 therefore, serve as mere conduits for nutrient fluids which 



* KoUiker's ' Manual of Microscopic Auatomy,' page 307. 



