A VI AN TUBERCULOSIS. 225 



points of distinction existed between the tubercle bacilli 

 from mammals and those from birds, though he did not 

 conclude therefrom that they were quite distinct species. 

 Maffucci and Rivolta had already drawn attention to, and 

 studied, these differences. 



On glycerine-agar and on serum, the growth of tubercle 

 bacilli from birds is more luxuriant, has a moister appearance 

 (Fig. 58, C), and, moreover, takes place at a higher tempera- 

 ture, 43.5 C, than is the case with ordinary tubercle bacilli. 

 Experimental inoculation brings out even more distinct 

 differences. Tubercle bacilli derived from the human 

 subject, for example, when injected into birds, usually fail to 

 produce tuberculosis, whilst those of avian origin very readily 

 do so. Birds are also very susceptible to the disease when 

 fed with portions of the organs of birds containing tubercle 

 bacilli, but they can consume enormous quantities of 

 phthisical sputum without becoming tubercular (Straus, 

 Wurtz, Nocard). No doubt, on the other hand, there are 

 cases on record in which the source of infection of a poultry 

 yard has apparently been the sputum of phthisical patients. 

 Again, tubercle bacilli cultivated from birds have not the 

 same effect, on inoculation of mammals, as ordinary tubercle 

 bacilli. When guinea-pigs are inoculated subcutaneously 

 sometimes death follows ; generally, however, it does not. 

 In the former case, usually no tubercles visible to the 

 naked eye are found, but numerous bacilli may be present in 

 internal organs, especially in the spleen, which is much 

 swollen. Intravenous injection in guinea-pigs and rabbits 

 produces a fatal result, in the case of the latter in two or 

 three weeks, but here again there is no eruption of ordinary 

 tubercles, though there may be marked enlargement of the 

 spleen and the number of bacilli in it and other organs may 

 be very great. Further, intravenous injection even of large 

 quantities of avian tubercle bacilli, in the case of dogs, leads 

 to no effect, whereas ordinary tubercle bacilli produce acute 

 tuberculosis. 



There is, therefore, abundant evidence that the bacilli 

 derived from the two classes of animals show important 



