100.)]

[Illustration: FIG. 20.--Agar Milk Sugar Culture.
Deep-lying colony of granule bacillus from calf's stomach.
The form of the colony is often determined by the relative
presence or absence of air. (Two days at 37 deg. C. Enlarged
about 1:50.)]

[Illustration: FIG. 21.--Agar Milk Sugar. Colony of
_Bacterium W._ from Yoghourt (non-granular variety of the
granule bacteria, as far as possible identical with
Luersen and Kuehn's _Bacillus bulgaricus_), of a cubical
branching-out form.

According to Kuntze, the granule formation of this and
related organisms is variable, while White and Avery
regard it as a constant characteristic. (Incubated two
days at 37 deg. C. Magnified x 50.)]

[Illustration: FIG. 22.--Two colonies of _Bacillus
acidophilus_ from calf's manure. Agar Milk Sugar Culture.
With this organism, also, we have conformation to one type
of colony, while, in other respects, temperature
requirements and production, etc., we have close agreement
with the granule bacillus (_Bacillus bulgaricus_). (Two
days at 37 deg. C. Enlarged about 1:50.)]

[Illustration: FIG. 23.--Beer-wort Gelatine.
Fourteen-days-old colony of Yoghourt yeast. (Enlarged
about 1:50.)]

[Illustration: FIG. 24.--Shredded preparation of the
Bulgarian original Yoghourt. Stain: aqueous methylene
blue. Granule bacillus, diplostreptococci, and yeast. (See
also other photo-micrographs of Yoghourt. Enlarged
1:70.)]

[Illustration: FIG. 25.--Granule Bacillus from Yoghourt.
Cultivated in skim milk in twenty-four hours at 37 deg. C.
Stain: aqueous methylene blue. (Enlarged 1:50.)

By means of this staining treatment the presence of
granules (not spores) can be easily detected. Treatment
with fuchsine fails to bring out these formations.]

[Illustration: FIG. 26.--_Bacteria W._, Agar Milk Sugar
Culture. Cultivated twenty-four hours (knobs, clubs).
Stain: Gram's method coloured with aqueous fuchsine
afterwards. (Enlarged 1:600.)]

[Illustration: FIG. 27.--_Bacteria acidophilus_ from
calves' manure, isolated by means of bouillon as acid as
vinegar. Shredded out of the usual Agar culture.
Twenty-four hours at 37 deg. C. Stain: aqueous methylene blue.
(Enlarged 1:700.)]

[Illustration: FIG. 28.--Mucus from calf's stomach
inoculated into milk after eight transferrings. Shredded
preparation cultivated in milk for twenty-four hours at
37 deg. C.