infection. The
contamination of solid food from flies and other sources is, of
course, a possibility, but tuberculous meat from cattle and swine is
much more likely to occur, although it must be said that the
processes of preparing such food for use (roasting, frying, and
boiling) are sufficient to destroy the vitality of the causal
organism. The fact that most food products of this character are now
inspected renders this possibility less likely to occur.

Unquestionably, the likelihood of ingesting tubercle organisms is
much greater with milk than with any other food supply, as milk is
consumed usually in an uncooked state, and as microscopic and
physiologic tests indicate that not infrequently milk from
tuberculous animals contains these organisms.

=Distribution of the disease in animals.= As practically any organ of
the body may be affected with tuberculosis, it naturally follows
that the lesions of this disease are widely distributed. The disease
germ is introduced, in the main, through the lymph and not the blood
system; consequently, in the initial stages the evidence of
tuberculosis is often comparatively slight, and the lesion is
restricted in its development. Where such a condition obtains, it is
known as "closed," in contradistinction to "open" tuberculosis,
where the diseased tissue is more or less broken down and is
discharging into the circulation, or elsewhere. Manifestly, the
danger of spreading not only in the affected animal itself, but to
the outside, is much greater in the case of the open lesion.
Especially is this true where the disease is present in the lungs or
organs that have an exterior opening so that the material containing
the organisms is discharged from the body in the sputum, manure,
urine or milk. The intestines themselves are rarely affected, but
the lymph glands associated with the intestinal tract are not
infrequently involved.

=Infection of milk with tubercle bacilli.= In a small percentage of
cases, the udder itself becomes involved. Where this condition
obtains, one or more hard lumps are formed, which slowly increase in
size, usually being restricted to one quarter of the udder.
Sometimes the affected quarter may develop to an enormous size,
producing a hard, painless tumor. Not often does the affected tissue
break down into pus; consequently, no abnormal appearance is to be
noted in the milk secretion until the disease has made very extended
progress, in which case the pe