AVIAN TUBERCULOSIS. — EXPERIMENTAL STUDY. 537 



In two cases the lesions were again very different from those usually 

 observed ; the abdominal organs were normal, the lungs alone con- 

 taining two or three pearly tubercles, the size of millet-seeds, projecting 

 beneath the pleura. 



Microscopic examination of these lesions revealed bacilli remarkable 

 for their size, which was somewhat greater than that of the human 

 bacillus, and for their more granular appearance. 



The pulmonary new growths were formed of a mass of epithelioid 

 cells ; giant-cells were absent, and the periphery of the lesions exhibited 

 very few embryonic cells. 



The hepatic tubercles had a special appearance. In one case the 

 granules were formed of a caseous centre surrounded by a fibrous zone ; 

 in another, a tubercle had been entirely transformed into a fibrous 

 mass ; this was unquestionably a tubercle in course of healing. 



Histological study, therefore, showed that the lesions produced in 

 guinea-pigs by inoculation with avian tuberculosis tend to become 

 localised and to heal. This tendency towards spontaneous recovery 

 had already been suggested by the course taken by the local tubercle 

 resulting from inoculation and by the glandular inflammation. 



To sum up, avian tuberculosis behaves quite differently in the rabbit 

 and in the guinea-pig. This fact, which escaped Rivolta and Maffucci, 

 and which we were the first to note, has been confirmed by the 

 researches of different authors, and by the results of further experi- 

 ments which we have carried out. Thus we are led to conclude that 

 avian, unlike human tuberculosis, is more active in the rabbit than in 

 the guinea-pig. In the latter animal it either causes no lesions, or 

 gives rise to a caseous abscess, or finally produces a few rare visceral 

 tubercles, which scarcely interfere with the animal's general health, and 

 tend to undergo fibrous transformation, that is, to heal. 



But although the results just noted are generally constant, they 

 are subject to certain exceptions. 



A guinea-pig which had been inoculated with a fragment of liver 

 from a fowl, which again had been inoculated from the liver of a 

 pheasant, died at the end of 103 days. At the autopsy it was found 

 suffering from generalised miliary tuberculosis ; the peritoneum con- 

 tained a certain quantity of serous liquid ; the liver, which weighed 

 if ounces, and the spleen, which weighed 2j drachms, were crammed 

 with tubercles ; the lungs also showed granulations. The lesions 

 were, in fact, similar to those seen after inoculation with human tuber- 

 culosis. 



From this guinea-pig a second was inoculated. The latter remained 



