734 Tuberculosis 



them upon food containing tubercle bacilli, and keeping them in 

 cages in which dust containing tubercle bacilli was placed. The 

 infection was aided by lowering the temperature of the birds with 

 antipyrin and lessening their vitality by starvation. 



Morphologic Peculiarities. — Morphologically, the organism found 

 in avian tuberculosis is similar to that found in the mammalian 

 disease, but is a little longer and more slender, with more marked 

 tendency to club and branched forms. Fragmented and beaded 

 forms occur as in the human tubercle bacilli. 



Staining. — The avian bacillus stains in about the same manner 

 as the human and bovine bacilli and has an equal resistance to 

 the decolorant effect of acids. 



Cultivation. — Marked rapidity and luxuriance of growth are 

 characteristic of the avian bacillus, which grows upon ordinary 

 agar-agar and bouillon prepared without glycerin. 



The growth also lacks the dry quality characteristic of cultures 

 of the human and bovine bacilli. Old cultures of the bacillus of 

 fowl tuberculosis turn sHghtly yellow. 



Thermic Sensitivity. — ^The bacillus also differs in its thermic 

 sensitivity and will grow at 42° to 45°C. quite as well as at 37°C., 

 while the growth of the human and mammalian bacilli ceases at 

 42°C. Moreover, growth at 43°C. does not attenuate its virulence. 

 The thermal deathpoint is 7o°C. Upon cultiure-media it is said to 

 retain its virulence as long as two years. 



Pathogenesis. — Birds are the most susceptible animals for ex- 

 perimental inoculation, the embryos and young being more sus- 

 ceptible than the adults. Artificial inoculation can be made in the 

 subcutaneous tissue, in the trachea, and in the veins; never through 

 the intestine. After inoculation the birds die in from one to seven 

 months. The chief seat of the disease is the liver, where cellular 

 (lymphocytic) nodes, lacking the central coagulation and the giant- 

 ceU formation of mammalian tuberculosis, and enormously rich in 

 bacilli, are found. The disease never begins in the lungs, and the 

 fowls that are diseased never show bacilli in the sputum or in the 

 dung. 



Guinea-pigs are quite immune, or after inoculation develop cheesy 

 nodes, but do not die. 



Rabbits are easily infected, an abscess forming at the seat of 

 inoculation, nodules forming later in the lungs, so that the dis- 

 tribution is quite different from that seen in birds. It is possible 

 that the avian bacillus occasionally infects man. 



The possibihty that this bacillus is derived from the same stock 

 as the tubercle bacillus is strengthened by the experiments of 

 Fermi and Salsano,* who succeeded in increasing its virulence until 

 it became fatal to guinea-pigs, by adding glucose and lactic acid to 

 the cultures inoculated. 



* "Centralbl. f. Bakt.," etc., xii, 750. 



