274 BACTERIOLOGY. 



scales, and a new generation started. The scales 

 gradually increase in size, and consist entirely of 

 bacilli. In about three to four weeks the cultivation 

 ceases to increase, and it is then necessary to 

 inoculate a fresh tube. The virulence is not 

 weakened by carrying on successive cultivations. 

 A relatively small portion of the cultivation inocu- 

 lated into the subcutaneous tissue, into the peritoneal 

 or pleural cavity, into the anterior chamber of the 

 eye, or directly into the blood stream, produces 

 after three or more weeks artificial tuberculosis in 

 guinea-pigs and rabbits. Dogs and cats can also 

 be infected by experimental inoculation. 



The appearances observed at the autopsy are, 

 swollen lymphatic glands in the neighbourhood of 

 the inoculation, followed by softening and abscess; 

 enlargement of the spleen and liver, with for- 

 mation of caseous tubercles ; tuberculosis of the 

 lungs, bronchial glands, and peritoneum. After 

 inoculation of the eye, grey tubercles appear on 

 the iris, and undergo enlargement and caseation, 

 followed by tuberculosis of the eyeball and organs 

 generally. The bacilli appear to be the direct 

 cause of tuberculosis, and the presence of the 

 bacillus in the sputum of patients is regarded 

 as a distinctive sign of the existence of this 

 disease. The detection of the bacillus has, con- 

 sequently, become a test which is daily applied 

 by physicians in forming clinical diagnoses. 



The bacilli are found in all tubercular growths 



