th at blood temperature, it appeared
necessary to procure cultures of lactic bacteria able to grow at
temperatures of 100 deg. F. to 112 deg. F. Such an organism was found in
Bulgarian soured milk (yoghourt), and was considered pre-eminently
adapted to this purpose. As has been shown in the preceding paragraphs,
this organism is merely one of a large group of bacteria found
distributed in the intestinal canal of many domestic animals, in manure,
and in ordinary market milk. It is then not surprising that the
introduction into the intestinal tract of bacteria of the type
_Bulgaricus_ in the form of tabloids has not met with any decided
success. Although it was considered to be merely necessary to introduce
the desired type of organism into the body, and the amount of lactic
acid taken into the system by the administration of soured milks was
looked upon as of secondary importance, yet, it would seem, in the light
of recent investigations, that benefits derived from a soured milk
regimen are attributable in part to a chemical as well as a purely
bacterial action. This receives support from the fact that soured milk
beverages prepared by the use of ordinary lactic bacteria, distinct from
those of the _Bulgaricus_ type, often exert a beneficial influence upon
human beings even although the organisms responsible for the
fermentation are incapable of growth at blood temperature.

It may be mentioned in conclusion that cultures prepared by the use of
organisms of the type _Streptococcus lacticus_ combined with _Bac.
bulgaricus_ possess a more agreeable flavour and aroma than those
prepared from a pure culture of _Bulgaricus_ alone.

[Illustration: FIG. 35--_Bacillus bulgaricus_, showing the
cultures in English cow's milk. (Magnified 450 diams.)]

[Illustration: FIG. 36--Photo-micrograph of pure culture
of _Bacillus bulgaricus_. The administration of cultures
of this organism is indicated in all cases of intestinal
ailments, caused by the excessive growth of proteolytic
bacteria, and consequent putrefaction of foods in the
alimentary tract. By the formation of large quantities of
lactic acid, a state of asepsis is ensured, which is
particularly valuable in cases of operations on the
abdomen and intestines.]

[Illustration: FIG. 37.--Photo-micrograph of smear of
combined culture of _Bacillus bulgaricus_ and _Bacteria
paralacticus_. This double culture possesses an advantage
over single culture