260 



MICROBIOLOGY 



protect itself by suppressing multipli- 

 cation rather than by attempting to 

 neutralize such poisons." 



Bacterium of avian tuberculosis. 



This organism is more readily obtained 

 in pure cultures directly from tissues 

 than either the human or the bovine 

 species. Moore 33 obtained it in about 

 20% of the serum tubes inoculated di- 

 rectly from the organs. A measure- 

 ment of over two hundred individual 

 organisms in cover-glass preparations 

 made directly from organs of fowls gave 

 the following: In the liver the lengtk 

 varied from 1.2 to 3.5 /z, in the spleen 

 and in the skin they varied from 1 to 

 4 /JL in length. A general average gave 

 a length of 2.7 p. They often appear in 

 these preparations in dense masses. 

 Chains made up of a number of short 

 elements are rarely present. Granules 

 are occasionally observed. In the 

 preparations from the skin a consider- 

 able number of them contain polar 

 granules and not infrequently three 

 such bodies were noticed in a single in- 

 dividual. Perhaps the most striking 

 feature concerning these organisms in 

 the tissues is. their enormous numbers-. 

 Sibley * has called attention to the sim- 

 ilarity of avian tubercle bacteria to 

 those of leprosy in that they multiply 

 to such enormous numbers without a 

 pronounced breaking down of the tis- 

 sues. 



Morphology. The morphology of 

 83 Moore, loc. cit. 



* Sibley (Jour, of Comp. Med. and Vet. Archives, 1890) pointed 

 out the resemblance of avian tuberculosis to leprosy. 



Fig. 58. A glycer- 

 in agar culture of 

 avian tubercle bac- 

 teria, showing colon- 

 ies. Four weeks old. 



