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82 THE MICRO-ORGANISMS OF THE HUMAN MOUTH.

base and point; they sometimes appear straight, sometimes
irregularly curved, sometimes twisted in regular spirals either
throughout or only at the point or base. Now and then a spirulina
may be observed. I liave not been able to determine whether
this fungus has any causal relation to the disease.
The question arises whether this organism may not also occur
on the teeth of other carnivora, or even of phytophagous mam-
mals. In order to determine this point, I examined the teeth of
various animals and found very frequently leptothrix-like fungi
in the mouths of sheep, cattle, pigs, horses, and so forth.
It can be determined by pure culture alone whether these
species of Leptothrix, occurring in different animals, are identical
or not. Some of them, at least, show morphologically great simi-
larity; in general, however, those of the cat and rabbit seem to
be more delicate and thin than those of the dog.
Mouth-Bacteria which give a Blue or Violet Reaction with
Iodine.
Besides the Bacillus buccalis maximus and Jodococcus vagi-
natus, the following mouth-bacteria may be mentioned which
give the iodine reaction described above :
a. A micro-organism which I shall for the present term JotJo-
coccus magnus ; large cocci or diplococci of differ-
ent sizes (Fig. 31). I first succeeded in obtaining
FiG. 31.
a pure culture of this micro-organism on a medium
g o
composed of equal parts of agar-agar gelatine and
^ o '®a ®.,
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©. & Q
y^ a solution of dentine glue sufficiently thick to
become stiif at room temperature. In addition to
these ino-redients, the medium contained 1.5 per
°,y?-?^^c^^
800:1. cent, of sugar and 1.5 per cent, of starch. If a
small quantity of the soft deposit upon the necks
of teeth be brought upon this medium after the manner employed
in making line-cultures, a copious growth of difl'erent micro-
organisms will be observed in twenty -four to forty-eight hours,
if kept at the temperature of the human body. AVe now pour
a slightly acidulated solution of iodine in iodide of potassium
uponjthe plate. The culture-medium itself becomes bluish, most
of the colonies yellowish; some individual points, however, often

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