290 MANUAL OF BACTERIOLOGY. 



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 sunlight. It is destroyed in a few minutes by 

 boiling.. 



It is not known to grow outside of the animal body. It 

 is the cause of tuberculosis in man. It produces tubercu- 

 losis 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 in- 

 oculated 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 swelling of the 

 neighboring 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 ((lerman, J'crJsuc/if} is characterized by large. 

 nodular lesions, \\itb a marked tendency to become fibrous, caseous 

 and calcified. Tbe tubercle bacilli of cattle differ somewhat from those 

 of human tuberculosis, as was noted by T. Smith. 1 \Yhether or not 

 men could be infected with bovine tubercle bacilli, 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. 2 It seems possible that the danger of infection from cattle has 

 been somewhat overrated. 



The lesion produced by the tubercle bacilli 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 



^Journal Experimental Medicine, Vol. TIL, p. 451. 



2 T. Smith, Medical Xe-^'s. February 22, 1902 ; Salmon, Bureau of 

 Animal Industry. Bui. \>. .^ : Adami, Philadelphia Medical Journal, 

 February _>2, iuo_>: Ravenel, Unirersity of Pennsylvania Medical 

 bulletin. May, 1902; Larti.uau. Journal Medical Research. Vol. VI., 1901. 



