DIAGNOSIS OF TUBERCULOSIS 459 



CULTURAL CHARACTERS. 



Glycerin bouillon, after two to four Glycerin bouillon, delicate membrane 



weeks' growth, dense wrinkled membrane. exhibiting occasional wrinkling of the 



surface. 



Reaction remains permanently acid. Reaction gradually becomes alkaline. 



Tuberculin has acid reaction. Tuberculin has alkaline reaction. 



Growth on blood serum relatively Growth on blood serum relatively 



luxuriant and develops with comparative meagre develops slowly, 

 rapidity. 



ANIMAL PATHOGENESIS. 



Guinea-pigs very susceptible. Young Guinea-pigs, young cattle, rabbits and 



cattle, rabbits and swine resistant to swine very susceptible to infection, 

 infection. 



Bovine infections in man are much more common in children than 

 in adults 1 Milk is a frequent vehicle for the transmission of the virus 

 to man; the origin of the bacilli in milk has been summarized by 

 Moore 2 as follows: 



"1. Cows with tuberculous udders eliminate tubercle bacilli with 

 the milk. In such cases these organisms are usually present in large 

 numbers. 



2. Cows with glandular or pulmonary tuberculosis, in which the 

 lesions are discharging into the bronchi, eliminate tubercle bacilli 

 with the feces and with the droolings. In cases of intestinal tuberculous 

 ulcers the organisms are excreted with the feces. 



3. Milk is usually infected with tubercle bacilli when it is taken 

 from cows with tuberculous udders. It may, through contamination 

 with feces or uterine discharges, be infected when drawn from cows 

 with open lesions in the respiratory and digestive tracts or organs of 

 reproduction. 



4. Tubercle bacilli are not, as a rule, present in milk of cows that 

 react to tuberculin and which, on careful physical examination, exhibit 

 no evidence of disease." 



The identification of tubercle bacilli in milk presents no insurmount- 

 able difficulties, but certain precautions must be observed. Prudden 

 and Hodenpyl, 3 Straus and Gamaleia 4 and others have shown that the 

 injection of killed tubercle bacilli into guinea-pigs by the intraperi- 

 toneal route will induce tubercle formation even if the organisms have 

 been heated in the autoclave. These tubercles, however, if crushed 

 and injected into fresh animals, do not reproduce tubercles. It is 

 obvious that the injection of pasteurized milk containing dead tubercle 



1 Statistics by Park and Krumwiede, p. 438. 



2 Jour. Med. Research, 1911, xxiv, 517. 



3 New York Med. Jour., 1891, liii, 637, 697. 

 * Arch. med. exper., 1891, iii, 705. 



