MILK FROM TUBERCULOUS COWS. 
127 
Other methods of distribution are of importance, however, 
and until within a few years have not received attention from 
the medical profession at all commensurate with their value. 
These methods of infection are those arising from the inges¬ 
tion of food materials coming from the domestic animals, 
especially the flesh and milk of cattle. 
In Koch’s Etiology of Tuberculosis he uses the following 
expressions: 
“ Since by far the greatest number of cases of tuberculosis 
begin in the lungs, it is to be supposed that the infection in all 
these cases has taken place in the manner just suggested—by 
the inhalation of phthisic sputum dried and made into dust. 
The second principal source for the tubercle-bacilli, viz., 
tuberculosis of the domestic animals, appears not to have any¬ 
thing like the importance of the phthisic sputum. The 
animals, as is well known, produce no sputum, so that during 
their life no tubercle-bacilli get from them into the outer 
world by means of the respiratory passages. Also in the ex¬ 
crement of tuberculous animals the bacilli appear to be only 
exceptionally present. On the contrary, it is a fact that the 
milk of tuberculous animals can cause infection. 
‘‘With the exception of this one way, therefore (i. e ., 
through milk) the tuberculous virus can only have effect after 
the death of the animal, and can only cause infection by the 
eating of the meat. The same conditions hold for the milk of 
cows suffering from ‘perlsucht.’ Before all things, if infec¬ 
tion is to take place, it is necessary that the milk contain 
tubercle-bacilli; but this appears to be the case only when the 
milk-glands themselves are affected with the disease. This 
explains at once the contradictions in the statements of various 
authors, who have made feeding experiments with the milk 
of cows suffering from ‘ perlsucht.’ If infection from tubercu¬ 
lous animals does not appear to be frequent, it must by no 
means be underrated.” 
This caution is one which was necessary at the time it was 
written, and its repetition is as necessary now as ever. What 
conclusions may be reached in regard to its extreme import¬ 
ance, are well shown by the statistics collected and presented 
