urce of a culture of the tubercle bacillus
by its effect when it is inoculated upon cattle. One of the bovine cultures
failed to produce generalized tuberculosis in cattle, and some of the human
cultures did produce it in such animals. Moreover, while some of the human
cultures caused no disease at all, others led to the development of minute
foci in the prescapular glands, and still others to somewhat more marked
disease of the glands. There were, consequently, four degrees of virulence
noted in these 39 cultures of bacilli from human sources and three degrees
of virulence in the 7 cultures from animal.

Now, if we accept the views of Koch as to the specific difference between
human and bovine tubercle bacilli, and that the human bacilli produce only
localized lesions in cattle, while bovine bacilli produce generalized
lesions in them, must we not conclude that the one non-virulent bovine
culture was in reality of human origin, and that the animal from which it
was obtained had been infected from man? This is a logical deduction, but
reverses the dictum laid down at London that human tuberculosis is not
transmissible to cattle. Again, how are we to explain the human cultures of
medium virulence? Are they human bacilli which, for some unknown reason,
are increasing in virulence and approaching the activity of the bovine
bacillus, or are they really bovine bacilli which have multiplied in the
human body until their virulence has become attenuated? In whatever manner
these questions are decided it would seem that the findings of the German
commission, instead of supporting Koch's views that we can decide with
certainty by the inoculation of cattle as to the source of any given
bacillus, really show that this method of diagnosis is extremely uncertain
in the present condition of our knowledge.

It is definitely admitted that 4 of the human cultures caused generalized
tuberculosis in cattle; Kossel suggest, however, that it may be possible
that the bacilli in cases of human tuberculosis under certain circumstances
can likewise attain a very high pathogenic activity for cattle without
being for that reason bovine bacilli. Undoubtedly the German commission is
confronting the two horns of a dilemma, either one of which is fatal to the
views of Koch as stated with such positiveness at London. If we accept this
suggestion thrown out by Kossel, we must conclude that Koch was wrong in
his claim that human tuberculosis can not be tr