254 TUBERCULOSIS. 



bird, as in some cases inoctilation with tubercle ba'cilli of avian 

 origin has produced ordinary tubercle nodules in guinea-pigs 

 (Courmont and Dor). We may add that tuberculin prepared 

 from avian tubercle bacilli has the same action as the ordinary 

 tuberculin. 



3. Tuberculosis in the Fish. Bataillon, Dubard, and Terre 

 cultivated from a tubercle-like disease in a carp, a bacillus which, 

 in staining reaction and microscopic characters, closely agrees 

 with the- tubercle bacillus. The lesion with which it was asso- 

 ciated was an abundant growth of granulation tissue in which 

 numerous giant-cells were present. It forms, however, luxuriant 

 growth at the room temperature, the growth being thick and 

 moist like that of avian tubercle bacilli (Fig. 94, c). Growth 

 does not occur at the body temperature, though by gradual 

 acclimatisation a small amount of growth has been obtained up 

 to 36 C. Furthermore, the organism appears to undergo no 

 multiplication when injected into the tissues of mammals, and 

 attempts to modify this characteristic have so far been unsuc- 

 cessful. An interesting fact, however, in connection with this 

 subject is that it has been found possible to alter the conditions 

 of growth of the tubercle bacillus from the human subject so 

 that it flourishes at lower temperature than normal. This has 

 been effected by allowing it to remain for some time in the 

 tissues of the frog, its optimum temperatures of growth after a. 

 time being 28-3O C. and Moeller, by a similar proceeding in 

 the case of the blindworm, produced marked modification, so 

 that the organism no longer grew above 28 C., whereas it flour- 

 ished at the room temperature. Dubard also states that he has 

 succeeded in making the tubercle bacillus from a human source 

 assume the characters of the bacillus of fish tuberculosis. 



All the above facts taken together indicate that tubercle 

 bacilli may become modified in relative virulence and in condi- 

 tions of growth by sojourn in the tissues of various animals. 

 This modification appears slight, though of definite character in 

 the case of bovine tuberculosis, more distinct in the case of 

 avian tuberculosis, and much more marked, if not permanent, 

 in the case of fish tuberculosis, that is, of course, in their rela- 

 tions to the bacilli from the human subject. 



Other Acid-fast Bacilli. Within recent years a number of 

 bacilli presenting the same staining reaction as the tubercle 



