BACILLI IN CHRONIC INFECTIOUS DISEASES. 483 
of tuberculosis had given identical bacilli, and the bacilli of chicken tuber- 
culosis in their cand 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 
suchas are frequently observed in pathogenic bacteria, when these are culti- 
vated in pure cultures outside of the body fora 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 asimilar 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 todo. "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. 
Cadiot, Gilbert, and Roger (1891) have made a series of experi- 
ments 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 
bacilli from human tuberculosis. Of the guinea-pigs, which were 
inoculated in the cavity of the abdomen, eleven remained in good 
