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 6% 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 



