BACILLI IN CHRONIC INFECTIOUS DISEASES. 393 



pathogenic characters. Only in the tuberculosis of chickens I was not able 

 to apply this rule, as at that time it was not possible for me to obtain fresh 

 material from which to make pure cultures. As, however, all other forms 

 of tuberculosis had given identical bacilli, and the bacilli of chicken tuber- 

 culosis in their appearance and behavior towards the aniline colors entirely 

 corresponded with these, I believed myself justified in assuming their iden- 

 tity, notwithstanding the incompleteness of the research. Later I received 

 pure cultures from various sources, which apparently originated from tuber- 

 cle bacilli, but in several regards differed from these ; especially in the fact 

 that inoculation experiments, made by experienced and reliable investigators, 

 led to dissimilar results, which it was necessary to regard as unexplained con- 

 tradictions. At first I believed that these differences depended upon changes 

 such as are frequently observed in pathogenic bacteria, when these are culti- 

 vated in pure cultures outside of the body for a long time under more or less 

 unfavorable conditions. In order to solve the riddle I attempted by various 

 influences to change the common tubercle bacilli into the presumed variety 

 referred to. They were cultivated for several months at so high a tempera- 

 ture that only a scanty growth was obtained; in other experiments still 

 higher temperatures were allowed to act repeatedly for so long a time that 

 the cultures were brought as nearly as possible to the point of killing the 

 bacilli. In a similar way I subjected the cultures to the action of chemical 

 agents, of light, or absence of moisture ; they were cultivated for many gen- 

 erations in association with other bacteria ; inoculated successively in ani- 

 mals having but a slight susceptibility. But, in spite of all these attempts, 

 only slight variations were obtained in their characters far less than other 

 pathogenic bacteria undergo under similar circumstances. Itappears, there- 

 fore, that the tubercle bacilli retain their characters with special obstinacy ; 

 this is in accord with the fact that pure cultures which have now been cul- 

 tivated by me in test tubes for more than nine years, without in the mean- 

 time having been in a living body, are still entirely unchanged with the ex- 

 ception of a slight diminution of virulence. ... It happened about a year 

 ago that I received a living chicken which, wassuffering from tuberculosis, 

 and I used this opportunity to make cultures directly from the diseased or- 

 gans of this animal, which previously I had not been able to do. When the 

 cultures grew I saw to my surprise that they had precisely the appearance 

 and all of the characters possessed by the enigmatical cultures resembling 

 those of the genuine tubercle bacillus. Later I learned that these also ori- 

 ginated from tuberculosis in fowls, but, upon the assumption that all forms 

 of tuberculosis are identical, had been considered genuine tubercle bacilli. 

 A verification of my observations I find in the recently published researches 

 of Prof. Maffucci with reference to tuberculosis of fowls." 



According to Maffucci, adult chickens are refractory against the 

 action of the Bacillus tuberculosis from man, and there are slight 

 morphological and biological differences in the bacilli from the two 

 sources. 



Recently Cadiot, Gilbert, and Roger have made a series of ex- 

 periments with the bacillus of tuberculosis in fowls. They found 

 the bacilli to be very numerous in the livers of chickens suffering 

 from spontaneous tuberculosis, and inoculated with material from 

 this source six chickens, five rabbits, and twelve guinea-pigs. The 

 chickens, when inoculated in the cavity of the abdomen or by injec- 

 tion into a vein, died in from forty-one to ninety-three days from 

 general tuberculosis. Four of the rabbits died of general tuberculosis, 

 presenting the same appearance as that following inoculation with 

 31 



