is more sanitary to drain the dishes than to wipe
them.

286. Contamination from Unclean Dishcloths.--When the dishcloth is
foul, the fat absorbed by the fibers becomes rancid, the proteids
undergo putrefaction changes with formation of ill-smelling gases
containing nitrogen, the carbohydrates ferment and are particularly
attractive to flies, and all the various disease germs collected on the
surface of the dishcloth are, along with the rancid fat and other
putrifying materials, distributed over the surface of the dishes with
which the cloth comes in contact.

[Illustration: FIG. 69.--CONTAMINATION OF WELL WATER FROM SURFACE DRAINAGE.

(After Farmers' Bulletin, U. S. Dept. Agr.)]

287. Refrigeration.--At a low temperature the insoluble or unorganized
ferments become inactive, but the chemical ferments or enzymes are still
capable of carrying on fermentation. Thus it is that a food, when placed
in a refrigerator or in cold storage, continues to undergo chemical
change. An example of such enzymic action is the curing of beef and
cheese in cold storage. A small amount of ventilation is required when
foods are refrigerated, just sufficient to keep up a slight circulation
of air. It seems not to be generally understood that all fermentation
changes do not cease when food is placed in refrigerators, and this
often leads to neglect in their care. Cleanliness is equally as
essential, or more so, in the refrigeration of food as in its handling
in other ways. Too often the refrigerator is neglected, milk and other
food is spilt, filling the cracks, and slow decomposition sets in. A
well-cared-for refrigerator is an important factor in the preservation
of food, but when it is neglected, it becomes a source of contamination.
Unclean vegetables and food receptacles, impure ice and foul air, are
the most common forms of contamination. The chemical changes which
foods undergo during refrigeration are such as result in softening of
the tissues.

288. Soil.--The soil about dwellings and places where foods are stored
frequently becomes polluted with decaying animal and vegetable matter,
and in such soils disease-producing organisms readily find lodgment.
Poorly drained soils containing an excess of vegetable matter furnish a
medium in which the tapeworm and the germs of typhoid fever, lockjaw,
and various diseases affecting the digestive tract, may propagate. The
wind carries the dust particles from these contaminated places into