Dr. F. Hueppe, who has paid great attention to this subject, describes
five distinct organisms which he finds to be invariable accompaniments of
lactic fermentation. One of these he isolated on nutrient gelatine in the
form of white, shining, flat, minute beads. This organism has the power
of transforming milk sugar and other saccharoses into lactic acid, with
evolution of carbonic acid gas. It is rarely found in the saliva or
mucilage of the teeth. In these are two micrococci, both of which cause
the production of lactic acid, but which manifest differences in their
development under cultivation. There are also two pigment forming
bacteria, _Micrococcus prodigiosus,_ which produces intensely red spots,
and the yellow micrococcus of osteomyelitis. These five bacteria are so
different and so constant in their properties that they must, in Dr.
Hueppe's opinion, be regarded as distinct species. In addition to them
there is in milk an organism resembling _Mycoderma aceti_, which
transforms milk sugar into gluconic acid.
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