tle, was passed through a series of five cats. It was then
found to be completely changed in its morphological characters, the rods
being elongated, slender, more or less beaded, and entirely of the human
type. Far from decreasing in virulence, however, as might be expected from
its morphological appearance, this bacillus had so increased in its
pathogenic activity that it produced generalized tuberculosis in a cow.
This cow was inoculated subcutaneously in front of each shoulder with 2
cubic centimeters of a salt-solution emulsion of the tuberculous omentum of
the last cat of the series. The cow rapidly lost flesh, had a temperature
of 104 deg. F., with the point of inoculation and adjacent glands greatly
swollen. The autopsy revealed generalized tuberculosis, involving the
lungs, mediastinal glands, spleen, liver, and kidneys. Tubercle bacilli of
the bovine type obtained from the mesenteric glands of a sheep, hog, and
cow were similarly transformed in their morphological appearance after
being passed through a series of cats and recovered on dog serum. These
bacilli also increased in virulence, as the last cat in the series
invariably succumbed in a shorter time than the first of the series.

These experiments and observations indicate that the types of tubercle
bacilli are very inconstant, and that under suitable conditions they
readily change both in morphology and in virulence. A similar conclusion
was reached by other investigators in working with the avian and porcine
types of tubercle bacilli several years ago, and was reasonably to have
been expected with the human and bovine types.

Later investigations made by Park and Krumweide, of the Research Laboratory
of New York City, Novick, Richard M. Smith, Ravenel, Rosenau, Chung Yik
Wang, and others tend to show the incidence of bovine infection in the
human family. Chung Yik Wang stated in 1917 that studies of 281 cases of
various clinical forms of tuberculosis in Edinburgh, Scotland, resulted in
the isolation of the bovine tubercle bacilli in 78.4 per cent of cases
under the age of 5 years, in 70.3 per cent between the ages of 5 and 16,
and in 7.8 per cent over the age of 16. This investigator states that from
the prophylactic point of view any measure resorted to in combating the
disease should be directed not only against the human spread of infection,
but also, more particularly in children's cases, against the bovine source
of infection.

Ravenel, in summari