INFLUENCE OF DISEASE UPON MILK 81 
due to bovine infection. They had nine cases in a found- 
ling asylum in children under 6 years who were nourished 
exclusively on cow’s milk and found bovine infection in 
five, or over 50 per cent. Of the fatal cases in the Babies’ 
Hospital in New York City 614 per cent. were due to 
bovine infection. 
These observations cannot be ignored in considering 
the results of Weber and Ungermann’s investigation, 
especially since they all indicate that bovine tuberculosis 
is a considerable source of infection for children and are 
also in accord with the results of other studies of the 
disease. 
3. Conditions under which Milk is Infected with Tubercle 
Bacilli by Tuberculous Cows.—The milk of individual cows 
affected with tuberculosis in various forms has been 
tested for the presence of tubercle bacilli by injecting 
it into guinea pigs and by feeding it to these animals. 
Numerous experiments of this kind have been conducted, 
and upon the basis of these experiments tuberculous cows 
may be divided into three classes as regards the infectious- 
ness in their milk, viz: (a) Cows affected with tubercu- 
losis of the udder; (b) cows with apparently normal 
udders but showing clinical symptoms in other organs or 
parts, and (c) cows which do not show any clinical symp- 
toms but which have reacted to the tuberculin test. 
(a) Cows Affected with Tuberculosis of the Udder. 
—When the udder is tuberculous, tubercle bacilli are 
eliminated in the milk. In advanced or extensive cases 
of this form of the disease, the milk is very infectious; it 
contains from 50,000 to 100,000 and even 1,000,000 
tubercle bacilli per c.c. (Ostermann), and remains viru- 
lent when injected into guinea pigs after it has been 
6 
