ot produce disease in the human subject, but said:

It seems to me that, accepting the clinical evidence on hand, bovine
tuberculosis may be transmitted to children when the body is overpowered by
large numbers of bacilli, as in udder tuberculosis, or when certain unknown
favorable conditions exist.

Koch, however, in his address at the British Congress on Tuberculosis, went
far beyond this and maintained that "human tuberculosis differs from bovine
and can not be transmitted to cattle." As to the susceptibility of man to
bovine tuberculosis, he said it was not yet absolutely decided, but one was
"nevertheless already at liberty to say that, if such a susceptibility
really exists, the infection of human beings is but a very rare
occurrence." He emphasizes this view in the following language:

I should estimate the extent of infection by the milk and flesh of
tubercular cattle and the butter made of their milk as hardly greater than
that of hereditary transmission, and I therefore do not deem it advisable
to take any measures against it.

This conclusion was so radically different from the views of most
experimenters and so out of harmony with facts which had apparently been
demonstrated by others that it at once aroused opposition in the congress,
followed by the adoption of dissenting resolutions, and led to numerous
investigations in various countries. Koch's conclusions were based upon his
failure to produce tuberculosis in cattle and other animals by inoculating
them with tuberculous material of human origin and his success in causing
progressive and fatal tuberculosis in the same kinds of animals when
inoculated with tuberculous material of bovine origin. With such
positiveness did he hold to the constant and specific difference between
the human and bovine bacillus that he promulgated an experimental method of
discriminating between them. Speaking of the etiology of intestinal
tuberculosis in man, he said:

Hitherto nobody could decide with certainty in such a case whether the
tuberculosis of the intestine was of human or of animal origin. Now we can
diagnose them. All that is necessary is to cultivate in pure culture the
tubercle bacilli found in the tubercular material, and to ascertain whether
they belong to bovine tuberculosis by inoculating cattle with them. For
this purpose I recommend subcutaneous injection, which yields quite
specially characteristic and convincing results.

These important an