276 BACTERIOLOGY. 



local lesions whatever. It would seem to be possible, 

 therefore, that tubercular infection may be caused, under 

 certain conditions, by absorption through serous or 

 mucous membranes without the evidence of any local 

 lesion. 



The experimental production of tuberculosis by in- 

 halation of bacilli has been demonstrated by Koch in 

 guinea-pigs, rabbits, rats, and mice, and his results have 

 since been confirmed by many others; but in these ex- 

 periments the bacilli were usually inhaled in the form 

 of a very thin spray in which they were suspended. 

 The experimental inhalation of dry tubercular dust has 

 seldom proved successful. 



Various other tubercular affections which are natural 

 in man have been produced experimentally in animals, 

 as, for instance, tuberculosis of the joints (Pawlowsky), 

 tubercular abscess (Courmont), etc. 



It need hardly be said that the discovery of the 

 tubercle bacillus has elucidated the etiology of many 

 diseases the origin of which was formerly doubtful. 

 Among these may be mentioned the various forms 

 of tuberculosis of the lungs and other organs, lupus, 

 scrofula, fungoid inflammations of the bones and joints, 

 tuberculosis in cattle, monkeys, horses, swine, sheep, 

 goats, and the so-called spontaneous tuberculosis in 

 guinea-pigs and rabbits in cages in which healthy and 

 artificially infected animals have been kept together. 



Of domestic animals cattle are by far the most fre- 

 quently attacked by this disease. It is also not uncom- 

 mon in young swine. Monkeys, when they are kept in 

 confinement, die almost invariably from tuberculosis. 

 Among other domestic and wild animals it is a com- 

 paratively rare disease. Birds, with the exception of 



