claims to have found in
Emmenthaler cheese a digesting species, one of the Tyrothrix type, which
is capable of peptonizing the casein and at the same time producing the
characteristic flavor of this class of cheese. This organism, called by
him _Bacillus nobilis_, the Edelpilz of Emmenthaler cheese, has been
subjected to comparative experiments, and in the cheese made with pure
cultures of this germ better results are claimed to have been secured.
Sufficient experiments have not as yet been reported by other
investigators to warrant the acceptance of the claims made relative to
the effect of this organism.

~Lactic-acid bacterial theory.~ It has already been shown that the
lactic-acid bacteria seems to find in the green cheese the optimum
conditions of development; that they increase enormously in numbers for
a short period, and then finally decline. This marked development,
coincident with the breaking down of the casein, has led to the view
which has been so ably expounded by Freudenreich[199] that this type of
bacterial action is concerned in the ripening of cheese. This group of
bacteria is, under ordinary conditions, unable to liquefy gelatin, or
digest milk, or, in fact, to exert, under ordinary conditions, any
proteolytic or peptonizing properties. This has been the stumbling-block
to the acceptance of this hypothesis, as an explanation of the breaking
down of the casein. Freudenreich has recently carried on experiments
which he believes solve the problem. By growing cultures of these
organisms in milk, to which sterile, freshly precipitated chalk had been
added, he was able to prolong the development of bacteria for a
considerable period of time, and as a result finds that an appreciable
part of the casein is digested; but this action is so slow compared with
what normally occurs in a cheese, that exception may well be taken to
this type of experiment alone. Weigmann[200] inclines to the view that
the lactic-acid bacteria are not the true cause of the peptonizing
process, but that their development prepares the soil, as it were, for
those forms that are more directly concerned in the peptonizing process.
This they do by developing an acid substratum that renders possible the
more luxuriant growth of the aroma-producing species. According to
Gorini,[201] certain of the Tyrothrix forms function at high
temperatures as lactic acid producing bacteria, while at lower
temperatures they act as peptonizers. On this bas