500 PATHOGENIC MICROORGANISMS 



bovine bacilli, however, have been reported and proved beyond reason- 

 able doubt, by Smith,' Ravenel,^ Kossel, Weber, and Heuss,' Park and 

 Krumwiede,^ and others. Most of these infections have been in children. 

 It is likely, therefore, that while cattle are to a considerable degree im- 

 mune against the bacillus of the human type, human beings do not 

 enjoy the same safeguard in respect to the bovine bacillus. During adult 

 life, the danger of such infection, however, is far less than it is during 

 infancy and early youth. This question has been discussed on p. 487. 



The Bacillus of Avian Tuberculosis. — A disease resembling in many 

 features the tuberculosis of man is not uncommon among chickens, 

 pigeons, and some other bird species. Koch was the first to discover in 

 the lesions of diseased fowl bacilli much resembling Bacillus tuberculosis. 

 It was soon shown, however, by the studies of Nocard and Roux,^ 

 Mafucci,* and others, that the bacillus of the avian disease represented 

 a definitely differ entiable species. 



Morphologically, and in staining characteristics, the bacillus is 

 almost identical with that of the human disease. In culture, however, 

 growth is more rapid and takes place at a temperature of 41° to 45° CJ 

 (the normal temperature of birds), while the human type is unable to 

 thrive at a temperature above 40°. 



Guinea-pigs, very susceptible to human tuberculosis, are very 

 refractory to infection with the avian type; while, on the other hand, 

 rabbits which are resistant to the human type, succumb rapidly to in- 

 fection with avian tuberculosis.* Prolonged cultivation and passage 

 through the mammalian body is said to cause these bacilli to approach 

 more or less closely to the mammalian type. Conversely, Nocard ' 

 succeeded in rendering mammalian tubercle bacilli pathogenic for fowl 

 by keeping them in the peritoneal cavities of hens in celloidin sacs for 

 six months. 



Recently Koch and Rabinovitsch i" have isolated from the spleen of 



1 Smith, Trans. Assn. Amer. Phys., 1903. 



2 Ravenel, Univ. Penn. Med. Bull., 1902. 

 ^ Kossel, Weber, und Heuss, loo. cit. 



* Park and Krummiede, Jour. Med. Res., 1910. 

 ' Nocard et Roux, Ann. de I'inst. Pasteur, 1887. 

 « Mafmd, Zeit. f . Hyg., xi. 

 ' Mafucd, loc. cit. 



' Straus et Gamaleia, Arch, de mfid. exper., 1891; Courmont et Dor, Arch, de m^d. 

 exp., 1891. 



^ Nocard, Ann. de I'inst. Pasteur, 1898. 

 ^"Koch und Rabinovitsch, Virch. Arch., Beiheft to Bd. 190, 1907. 



