298 PUBLIC HEALTH BACTERIOLOGY 



and the third in six days, showed bacilli in the sub- 

 maxillary and mesenteric glands and spleen, the lung 

 condition, owing to the premature death of the guinea- 

 pigs used for the test, not being determined. 



Excretion of tubercle bacilli in milk was tested by 

 injection of cultures into healthy cows and goats. 



Subcutaneous injection of ioo mgr. of bovine culture into 

 a healthy milch cow caused its death thirty days later of 

 general tuberculosis. The udder was normal both to the 

 naked eye and on microscopical examination, yet guinea- 

 pigs fed with the animal's milk, by the end of the first week 

 after injection and subsequently, developed tuberculosis. 



Two other cows were injected with human tubercle 

 bacilli. One received ioo mgr. subcutaneously ; tubercle 

 bacilli were recovered from her milk in twenty-four 

 hours, and the milk in small doses caused tuberculosis in 

 guinea-pigs at every time of testing right up to 155 days 

 later, when the cow was killed and the udder was found 

 normal. The other received 10 mgr. intravenously, and the 

 milk contained the bacilli in twenty-four hours and up to 

 fourteen days later, but not subsequently. The animal 

 was killed in 182 days, and showed no tuberculous lesions. 



Six milch goats were similarly tested with bovine and 

 human bacilli, with confirmatory results. 



In 12 experiments on heifers, subcutaneous injection of 

 human virus (2), lupus virus (8), and bovine virus (2), in 

 50 to 100 mgr. doses, the heifers were killed in 62 to 127 

 days afterwards, and in eight cases tubercle bacilli were 

 found in the sinuses of the undeveloped udder of the 

 animals ; in four, in such numbers as to suggest multipli- 

 cation in these sinuses. 



Modification of Bacilli. Tests by cultural processes 

 and by long-continued passage through animals have 

 failed to effect any change of type from bovine to human, 

 bovine to avian, human to avian, and vice versa. Certain 

 difficulties were encountered with bacilli in lupus and in 

 the horse, but while the Reporters think that further 

 investigations may possibly disclose additional variations 

 in the types of bacilli, they do not as a result of their 

 investigations feel disposed to add a plurality of new 

 types to the three already described by them. They are 



