tion than the adult.

The danger of infection is much lessened in butter or cheese, because
the processes of manufacture tend to diminish the number of organisms
originally present in the milk, and inasmuch as no growth can ordinarily
take place in these products the danger is minimized. Moreover, the fact
that these foods are consumed by the individual in smaller amounts than
is generally the case where milk is used, and also to a greater extent
by adults, lessens still further the danger of infection.

Notwithstanding this, numerous observers[89] especially in Germany have
succeeded in finding the tubercle bacillus in market butter, but this
fact is not so surprising when it is remembered that a very large
fraction of their cattle show the presence of the disease as indicated
by the tuberculin test, a condition that does not obtain in any large
section in this country.

The observations on the presence of the tubercle bacillus in butter have
been questioned somewhat of late[2] by the determination of the fact
that butter may contain an organism that possesses the property of being
stained in the same way as the tubercle organism. Differentiation
between the two forms is rendered more difficult by the fact that this
tubercle-like organism is also capable of producing in animals lesions
that stimulate those of tuberculosis, although a careful examination
reveals definite differences. Petri[90] has recently determined that
both the true tubercle and the acid-resisting butter organism may be
readily found in market butter.

In the various milk products it has been experimentally determined that
the true tubercle bacillus is able to retain its vitality in butter for
a number of months and in cheese for nearly a year.

~Treatment of milk from tuberculosis cows.~ While it has been shown that
it is practically impossible to foretell whether the milk of any
reacting animal actually contains tubercle bacilli or not, still the
interests of public health demand that no milk from such stock be used
for human food until it has been rendered safe by some satisfactory
treatment.

_1. Heating._ By far the best treatment that can be given such milk is
to heat it. The temperature at which this should be done depends upon
the thermal death point of the tubercle bacillus, a question concerning
which there has been considerable difference of opinion until very
recently. According to the work of some of the earlier investigators,
the