PATHOGENIC BACTERIA. 289 



It is killed by 5 per cent, solution of carbolic acid in a few 

 minutes. In sputum it is destroyed in twenty-four hours by a 

 three per cent, solution of carbolic acid. It resists desiccation 

 for months, but is killed in some hours by direct sunhght. It 

 is destroyed in a few minutes by boiling. 



It is not known to grow, except in artificial cultures, outside 

 of the animal body. ■ It is the cause of tuberculosis in man. It 

 produces tuberculosis in apes, cows, sheep, horses, rabbits, 

 guinea-pigs, cats, field-mice and occasionally in other animals. 

 Guinea-pigs and rabbits are extremely susceptible. A guinea- 

 pig inoculated with tuberculous sputum (provided it does not 

 die of septicemia, due to the pyogenic micrococci which are fre- 

 quently present in sputum) will present a swelKng of the neigh- 

 boring lymph-nodes in the course of two to four weeks, and 

 will die as a rule in from four to eight weeks, although the time 

 may be longer. 



Tuberculosis in cattle (German, PerUuchl) is characterized by large, nodular 

 lesions, witb a marked tendency to become fibrous, caseous and calcified. The 

 tubercle bacilli of cattle differ somewhat from those of human tuberculosis, as 

 was noted by Theobald Smith.* Whether or not men could be infected with 

 bovine tubercle baciUi has been a question that has been warmly debated in 

 recent years. It seems to have been shown that such infection is possible; 

 also that it is possible that cattle may be infected with human tubercle bacilli. 

 Bovine tubercle bacilli are more virulent for some animals, as rabbits, than 

 human tubercle bacilli.t It seems possible that the danger of infection from 

 cattle has been somewhat overrated. 



The lesion produced by the tubercle baciUi in the tissues 

 of men and the lower animals is called a tubercle, which in 

 the beginning is a grayish-white area about the size of a 

 millet-seed. In secretions of the tissue young tubercles are 

 found to present several different structures. Near the 



* Journal Experimental Medicine. Vol. III., p. 451. 



t Theobald Smith. Medical News. February 22, 1902. Salmon. Bureau 

 of Animal Industry. Bulletin. No. 33. Adami. Philadelphia Medical Journal. 

 February 22, 1902. Ravenel. University oj Pennsylvania Medical Bulletin. 

 May, igo2. Lartigau. Journal Medical Research. Vol. VI. igoi. 



2S 



