Page 805 - My FlipBook

FERMENTATION IN THE HUMAN MOUTH. 815
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presents soft, milky ridges or knots raised sometimes a millimeter above
the surface of the gelatin and obtaining a width at the base of 3 to 6
mm. The y-fungus differs from all other fungi that I have yet found
in decaying dentine in tliat it completely liquefies the gelatin. The cul-
ture tubes present, therefore, a funnel-shaped area of liquefied gelatin,
while the fungi themselves fall to the bottom of the funnel. (See Fig.
423.)
This fungus forms furrows in the plates ; and if the plate is turned
on its edge, the w^hole mass of fungus flows from one end of the furrow
toward the other or slides quite off the plate.
The o-fungus (Fig. 421) forms completely opaque masses wdiich may
have a slight yellowish tinge, provided the gelatin itself is yellowish.
It has a small surface-growth and liquefies the gelatin only to a slight
extent. In cultures on plates which are two or three days old, the row
of fungus appears to lie in a trough or depression in the gelatin. It
does not move, however, when the plate is turned on edge. (See Fig.
424.)
For the funo-us of Fio;. 425 I have not yet been able to establish
definite peculiarities of growth. As far as my observations have at
present extended, it differs from that of Fig.
421 in that it is almost entirely wanting in ^^^- "^^S.
surface-growth and forms colorless masses iJ^C* ^'*'-v \>
even in colored media. It does not liquefy ^1^ vV?** "^^1'''*'^"'
the gelatin. Viewed by transmitted light, it lOi^"* | ^^-,4
appears to have a bluish tinge and a slight >^ ^ ^ \\
*'
opalescence. It grows, however, very slowly, '^*
V
and I have consequently as yet been unable to ,,1'
establish certain and definite characteristics for
it. The fungus described on page 802 grows still more slowly at gel-
atin temperature, and I cannot at present give any microscopical feat-
ures by which cultures on gelatin may be distinguished.
The most important feature connected with all these fungi, especially
the coccus-forms, is that they possess a ferment activity—in other words,
they are capable of producing acid out of sugar, or, in the human mouth,
out of starch, by the aid of the diastatic action of the saliva. They may
consequently all be looked upon as factors in the decay of the teeth. I
Avould not venture to say that the «-fungus is more concerned in the
process of caries than all the rest together ; nevertheless, such is the
constancy with which I have found it that if any one else should make
the assertion I would have no reason for contradicting him. Cultivated
in liquid substrata, none of them form films or skins upon the surface
of the liquid, but powdery or fleecy precipitates upon the bottom and
sides of the vessel. NoneJ so far as I have observed, produce an evolu-
tion of carbonic acid in solutions containing sugar, nor do they appear
to suffer when the access of oxygen is restricted.
A question of great importance not only for dentists, but for general
physicians—and, in fact, for everybody—is that relating to the ])ossible
pathogenic nature of these fungi. We find in the works of Leyden and
Jaffe, Haussman, Bollinger, James Israel, etc., sufficient ground for the
statement that " these fungi, in all parts of the human body which they