AVIAN TUBERCULOSIS. ETIOLOGY. 525 



is one of considerable importance, namely, that the dog reacts in an 

 entirely different way to the two viruses. It readily contracts human, 

 but resists avian tuberculosis. The authors were thus led to conclude 

 that the two bacilli are entirely different, and represent two distinct 

 species. 



On our side we continued the comparative study of the tubercu- 

 losis of birds and mammals. Our research, though prosecuted for the 

 past two 3'ears, is far from ended, but we have noted certain facts 

 deserving of publication. On the basis of our own researches, and of 

 others of earlier and later dates, we shall endeavour to set forth the 

 history of avian tuberculosis. 



II.— ETIOLOGY. 



Tuberculosis affects the fowl as well as man with remarkable 

 frequency. Of 600 fowls examined after death b}' Ziirn, 62 were 

 affected with tuberculosis. If this result truly reflects the facts tuber- 

 culosis would account for more than 10 per cent, of the mortality in 

 these birds. 



Pheasants, guinea-fowls, turkeys, peacocks, and pigeons are also, 

 though less frequently, victims of tuberculosis. In order to discover 

 the means by which the disease is introduced into aviaries and poultry 

 farms, we undertook several inquiries and addressed a list of questions 

 to nineteen owners or breeders who had sent us tuberculous birds. 

 Some gave no reply; others useless information. We were only able 

 to collect eight almost complete records of tuberculosis among fowls. 



In three of these epizootics tuberculosis had clearly been introduced 

 by newly purchased birds. The first outbreak attacked poultry with- 

 out affecting pigeons ; the second was confined to pheasants ; the 

 third to pheasants and poultry without affecting the peacocks. 



In the five other epizootics the origin of the disease remained 

 obscure. In three, fowls alone were affected ; in one, fowls and 

 turkeys ; in the last, pheasants. Of the three epizooties in which 

 fowls were affected one occurred in a new fowl run, which had only 

 been inhabited for eight months ; another in a fowl run occupied for two 

 years ; the last in a run where no new birds had been introduced 

 during the previous five years. The epizootics which attacked 

 pheasants had not been preceded by any importation of birds for a 

 very long series of years. 



In one of these cases we were able to discover that the person who 

 looked after the fowls coughed and expectorated a greal deal, but 

 examination of his sputum failed to reveal the presence of tubercle 



