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MICROSCOPICAL PHENOMENA OF DECAY. 193

on the part of the liviug pulp to retard the progress of the dis-
ease. But we can easily prove that such is not the case, since the
process occurs in living as well as in dead
FiQ. 90.
teeth. In accordance with the above
view, Tomes, Magitot, and others took Iff
"»
these granules for lime-granules: AVedl,
Black, and others regard them as fat.
By crushing the above-mentioned casts t
(page 191), grains are also produced in
the tubules which bear considerable re-
semblance to those which occur naturally)
Fig. 96).
I regard it therefore as not improbable
\
that the granular bodies have the same
Rod-Shapkd Formations in
origin as the rod-shaped (pipe-stems). Decayed Dextise
breaking up into granules.
1100 : 1.
4. Decay of Cement.
Decay of cement is confined chiefly to a very thin layer at the
Fig. 97.
(

f^mwM^'
Appearance of Decay in Crment with Prunouxced Development of the Cement-
Canai.s. «, surface of cement covered with various bacterium-forms; h, border of the den-
tine ; c, enlargement of the cement-canals and formation of liquefaction -foci ; d, spreading of
the decay into the dentine. 1100 : 1.
neck of the tooth. The decalcification and dissolution of the
cement proceeds either from the surface inward, in the form of
13