AVIAN TUBERCULOSIS. — EXPERIMENTAL STUDY. 543 



that is to say, at the end of 200 days, this animal, which had 

 continued in excellent health, was killed. On post-mortem examina- 

 tion two encysted caseous abscesses were found in the epiploon ; one 

 the size of a pea, the other of a small nut. The pus from these 

 abscesses, which contained very large numbers of bacilli, was 

 used for the intra-peritoneal injection of three guinea-pigs and a 

 fowl. 



The latter remained in good health, and was destroyed on the 

 gth April, i8gi, that is at the end of 172 days. At the site of each 

 injection was a yellowish flattened mass, as large as an almond, 

 formed of fibrous tissue, in the centre of which were seen round and 

 fusiform cells and hyaline masses. Although we were unable to dis- 

 cover bacilli on section, we regarded this growth as tuberculous, and 

 similar in character to the rice-like grains of certain cysts. But even 

 rejecting this interpretation, the fact none the less shows that during 

 their six months' sojourn in the organism of a guinea-pig the bacilli 

 had become incapable of producing an outbreak of tubercle in the 

 fowl. We cannot help comparing the above result with that obtained 

 by passing the tuberculosis of the pheasant through three mammals. 

 The reader will remember that in this case the virus was greatly 

 modified, and that it became incapable of killing members of the 

 Gallinaceae. 



Of the three guinea-pigs inoculated simultaneously with the fowl, 

 two died rapidly in sixteen and twenty days, as sometimes occurs after 

 inoculation with avian cultures. Autopsy only revealed a small local 

 lesion at the point of injection. The third bird appeared in good 

 health on the 12th March, 1891, five months after inoculation ; some 

 drops of an emulsion prepared with the liver of a guinea-pig, which 

 had died from inoculated human tuberculosis, were then injected into 

 the abdominal cavity. The animal died on the 3rd July, 1891. At the 

 autopsy caseous infiltration of both lungs was noted. The spleen, 

 which measured three inches in length and one and a half inches in 

 breadth, appeared red, and dotted over with white points; the hver 

 was large, and had a "nutmeg" appearance. Histological examina- 

 tion showed extremely extensive tuberculous infiltration. 



Here, then, was a guinea-pig which had perfectly resisted inoculation 

 wath avian tuberculosis, but had in no sense become immune against 

 human tuberculosis. It died as rapidly as the two control guinea-pigs 

 inoculated simultaneously. 



With this we may compare another precisely similar experiment. 



On the 2ist January, 1891, we inoculated two guinea-pigs with a 

 culture of avian tuberculosis ; they remained in good health. One was 



