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CARIES OF ANIMAL TEETH. 201

(Fig. 102). Here also, as tar as my observations reach, micro-
cocci are the chief destructive agents. In twenty wikl dogs,
forty foxes, and forty jackals I discovered no decay. Among
forty-four apes I found one having a molar tooth with a large
cavity extending to the pulp, and two molar teeth with small
cavities on the grinding-surface. Of a small number of porcu-
pines' skulls examined, one had
Fig 102
a molar completely broken down
by decay, nothing being left but
the thin walls.
In horses, decayed teeth are
frequently found. In the patho-
logical collection of the Berlin
veterinary school there are two
skulls in which nearly all the
molars show pronounced decay
on the grinding-surface. Other
skulls also had decayed teeth.
Out of about forty normal skulls '.%''
in the collection of the agricul-
tural school I found but one tooth
;./
which I could with certainty
pronounce as decayed. But it
is exceedingly difficult to recog-
nize decay in old, dry teeth of
horses unless it be already far
advanced. Dr. Galbreath men-
tions three badly decayed teeth
Group of Tcbcles from Dkxtine of
which he saw in the collection
THE Decayed Tooth of a Dog. 400 : 1.
of Prof. Dr. Glinther, of Han- In the side figure, piece of a tubule in the
beginning of the infection. IKX) : 1.
over.
The microscopical examination of decayed dentine from the
horse also showed the phenomena characteristic of human caries,
—invasions of bacteria, enlargement of the tubules, etc. (Fig.
103).
I have found the searching for decay in dry teeth of sheep
skulls no easy matter. The many folds, islands, and spaces
which are filled with remnants of food, and always intensely dis-