Page 212 - My FlipBook

184 THE MICRO-ORQANISMS OF THE HUMAN MOUTH.
highest ferment activity (in other words, aeid-forming power)
and the highest peptonizing power [i.e., dissolving power for
albuminous substances) and is able to flourish with a limited
supply of air will, cmteris jyaribus, cause a more rapid destruction
of the tooth-substance than another having these qualities in a
minor degree. A mouth-bacterium which in respect to these
properties excels all others in such a degree as would be neces-
sary to explain the difference between caries acuta and caries
chronica will most probably never be discovered. The rapid
advance of acute caries is to be explained rather by the resist-
lessness of the tooth's structure and the flivorable conditions for
fermentation obtaining in the mouth.
Successfully stained cuts of decayed dentine furnish prepara-
tions which to the eye of the bacteriologist and pathologist are
not only of exceeding great beauty, but also demonstrate with
such clearness the intense action of micro-organisms upon den-
tine that no doubting Thomas can look at them and then have
the hardihood to deny their significance. In Fig. 85 I have en-
deavored to reproduce the microscopic appearance of a specimen
in my possession (and of which I presented duplicates to Dr.
Cunningham, of Cambridge, England, and to Dr. Allan, of N'ew
York). If the reader can imagine the basis-substance in this
preparation stained yellowish-brown and the micro-organisms
red, and further take into account that by slightly lowering or
raising the tube of the microscope or by moving the prepara-
tion one constantly brings new and ditferent pictures into focus,
and, lastly, that the most skilled draughtsman and xylographer
come very short of nature, he may then form some idea of the
beauty of this specimen. The dentine is completely riddled by
the masses of bacilli and threads.
A section cutting the tubules at right angles shows under a
power of three hundred diameters that the tubules filled with
micro-organisms are distended from one to four times their nor-
mal diameter, and that often two or more of the enlarged tubules
are converted into one by the liquefaction of the membranes and
the intervening substance (Fig. 86). This melting together of
the tubules increases as we near the outer border of the speci-
men (corresponding to the surface of the cavity) until is no
it