AVIAN TUBERCULOSIS. 243 



the same nature. Dogs are much more highly resistant, but 

 tuberculosis can be produced in them by intraperitoneal 

 injection of pure cultures (Koch), or by intravenous injection 

 (Maffucci). In the latter case there results an extensive 

 eruption of minute miliary tubercles. 



Tuberculosis can also be easily produced in susceptible 

 animals by making them inhale the bacilli. Koch, for this 

 purpose, used pure cultures which were mixed with dis- 

 tilled water, and then distributed in the air by means of a 

 spray. Rabbits, guinea-pigs, and mice were exposed by 

 this means to inhalations for half an hour on three successive 

 days, and were afterwards kept in healthy conditions. 

 Some of the rabbits and guinea-pigs died within four weeks, 

 the others were killed at the end of that time, and all 

 showed pulmonary lesions which, in the case of the 

 rabbits and the guinea-pigs, were in the form of patches of 

 caseating catarrhal pneumonia. 



To obtain pure cultures of the tubercle bacillus, the acute 

 lesions in the organs of an animal recently killed should be 

 selected, e.g., the spleen of a guinea-pig with early acute tuber- 

 culosis. If the lesions are subacute or chronic with much 

 caseation, attempts at cultivation often fail. It would 

 appear as if a considerable number of bacilli required to be 

 present to start the growth, or it may be that many of the 

 bacilli found microscopically are actually dead. The 

 portions of tissue must, of course, be taken with aseptic 

 precautions, the knives, scissors, etc., to be used being 

 carefully sterilised, and the inoculations should be made on 

 solidified blood serum. 



Avian Tuberculosis. There can be no doubt that the 

 bacilli present in tuberculosis of the various mammals 

 mentioned are of the same variety, though differences in 

 virulence may be occasionally noticed. There has, how- 

 ever, of late years been considerable discussion as regards 

 the identity of the bacilli in avian and mammalian tuber- 

 culosis. In the tubercular lesions in birds there are found 

 bacilli which correspond in their staining reactions and in 

 their morphological characters with those in mammals, but 



