The manager of a well directed brewery, which was built according to
the latest improvements and provided with ice-cooling arrangements,
found that the alcoholic fermentation of lager beer did not advance
with proper regularity. The beer did not clarify well, it remained
turbid and had a tendency to assume a disagreeable odor and taste.
Microscopic examination of the yeast, however, showed the same to be
bottom yeast. After some time its action apparently diminished, or
rather, the fermentation, which began well, ceased, and at the same
time a white foam formed in the center of the vat. The manager
observing this, again submitted it to microscopic examination. The
instrument revealed a number of much smaller forms of fungi, similar
to those of young yeast, and some which were excessively large, a
variety never found in bottom yeast. Fully appreciating the
microscopic examination, and aware of the danger which the spread of
the fungi could cause, the manager resorted to all known means to
retard its pernicious influence. Fresh yeast was employed, and the
fermenting vats throughly cleaned, both inside and out, but the
phenomena reappeared, showing that the transmission took place through
the air. A microscopic examination of a gelatinous coating on the wall
of the fermenting room further explained the matter. Beginning at the
door of the ice cellar, the walls were covered with a gelatinous mass,
which, even when placed beneath the microscope, showed no definite
organic structure; however it contained numerous threads of fungi.
Notwithstanding the precautions which were taken for cleanliness,
these germs traveled from the ceiling through the air into the
fermenting liquid and there produced a change, which would ultimately
have caused the destruction of all the beer.
For a third time and by altogether different means, it was
demonstrated that the air was the bearer of these germs. The whole
atmosphere was infected, and a simple change of air was by no manner
of means sufficient, as has already been shown. In addition, these
observations throw considerable light on the means by which contagious
diseases are spread, for often a room, a house, or the entire
neighborhood appears to be infected. It must also be remembered how,
in times of plague, large fires were resorted as to a method of
purifying the air.
With the infinite distribution of germs, and as they are always
present in all places where any organic portions of vegetable or
animal matter are undergoing decomposition, it becomes, under certain
circumstances, exceedingly difficult, and at times even impossible, to
trace the direct effect of these minute germs. The organism is exposed
to the destructive action of the most minute creation; several changes
in this case give to them the direct effect of the acting germs. The
investigation of the chemist does not extend beyond the chemical
changes; nevertheless these phenomena are directly explained by the
microscope, without which, in the present case, the discovery of the
cause would have remained unknown.--_Arch. der Pharm._, 214, 158.
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