AVIAN TUBERCULOSIS. SUMMARY AND OONCLUSIONS. 555 



no appreciable lesion ; five showed a caseous abscess at the point of 

 inoculation ; seven a few discrete visceral granulations ; and three 

 generalised miliary tuberculosis. 



In passing through the organism of mammals, the avian virus be- 

 comes modified and loses its pathogenic properties for the fowl. 



In a second series of experiments we injected fowls with tuber- 

 culous material derived from man and from different mammals (ox, 

 dog, cat, and horse). Forty fowls were inoculated, either in the veins 

 or in the peritoneal cavity, or simultaneously in both. None died. In 

 five we found recent very small transparent tubercles ; they were due 

 to the human bacillus, for in one case they could be reinoculated into 

 the guinea-pig, but could not be transmitted to another fowl ; the virus 

 had therefore preserved its original properties. In another case the 

 bacilli became more markedly modified, and the lesions could be re- 

 inoculated from one fowl to another. 



The cases we have described, and the experiments published by 

 other observers, indisputably prove that profound differences exist be- 

 tween mammalian and avian tuberculosis. On the basis of the results 

 obtained, the following comparison may be established between the 

 two viruses. 



The avian bacilli are longer and more granular ; they develop more 

 readily on artificial culture media, and grow at once on glycerine agar. 

 The human bacilli only grow on this medium after having several times 

 been sown on serum. 



As MM. Straus and Gammeleia have well shown, cultures of the 

 avian bacilli are moist, fatty in appearance, wrinkled, and soft ; those 

 of the human bacilli are dry, scaly or warty, dull and hard. 



The avian bacillus grows at 43° C, and can resist a temperature 

 of 65° C. ; the human bacillus ceases to grow at 41° C, and dies at 

 65° C. 



An avian culture six months old is still living, and can still be re- 

 planted. A human culture loses its power of reproduction in six 

 months (Maffucci). 



Avian tuberculosis can be transmitted to fowls. It seldom or never 

 produces generalised tuberculosis in the guinea-pig, and cannot be 

 inoculated in the dog. Human tuberculosis can only exceptionally be 

 transmitted to fowls ; it always produces generalised tuberculosis in the 

 guinea-pig, and can readily be conveyed to the dog. 



Such are the differences between the two viruses, and it must be 

 confessed they are considerable. But are they sufficient to constitute 

 a radical distinction ? and must we regard the two bacilli as belonging 

 to different species ? 



