484 BACILLI IN CHRONIC INFECTIOUS DISEASES. 
health and one only died of general tuberculosis. These experi- 
ments show a decided difference in the pathogenic properties of 
tubercle bacilli from the two sources, for the guinea-pig is especially 
susceptible to tuberculosis as a result of similar inoculations with 
bacilli from human tuberculosis. We must therefore conclude that 
the bacillus found in spontaneous tuberculosis in fowls is a distinct 
variety of Bacillus tuberculosis. Whether this variety would cause 
tuberculosis in man, if introduced into susceptible subjects, has not 
been determined ; and, as pointed out by Koch, this question can 
only be answered in the affirmative if it should be obtained in pure 
cultures from cases of human tuberculosis. 
Since the above was written Maffucci has published (1892) an 
elaborate memoir upon tuberculosis of fowls. His conclusions are 
stated as follows : 
‘The bacillus cf tuberculosis in fowls is distinguished from that of tuber- 
culosis in mammals by the following points of difference: 
‘‘1. It does not induce tuberculosis in guinea-pigs, and seldom causes 
general tuberculosis in rabbits. 
‘©2. The cultures in various media havea different appearance from those 
of the Bacillus tuberculosis of mammals, 
' 3, The temperature at which it develops varies between 35° and 45° C., 
and the thermal death-point is 70° C. 
“4, At 45° to 50° C. the cultures show long, thick, and branched forms. 
‘“5. The bacillus retains its vegetative and pathogenic power at the end 
of two years. 
‘6, This bacillus produces a substance which is toxic for guinea-pigs and 
is but slightly toxic for grown fowls. 
‘“7, The tuberculosis produced in fowls by this bacillus is without giant 
cells.” 
Additional Notes upon the Tubercle Bacillus (1895).—Several 
authors (Metschnikoff, Czaplewski, Fischel) have described branch- 
ing forms of the tubercle bacillus, and Lubinsky (1895) reports that 
in certain media it grows out into long threads, which, however, he 
has never observed to be branched. The media used by him are said 
to give a more abundant growth than occurs upon glycerin-agar; 
the most favorable being made of flesh-peptone agar, or flesh-peptone 
bouillon, containing four per cent of glycerin and mashed _ potato, 
one kilo of finely chopped and washed potato to fifteen hundred cubic 
centimetres of water; this is cooked for three or four hours and filtered 
—to the filtrate is added four per cent of glycerin; one and a half 
per cent of agar is now added and the mixture is again cooked and 
filtered. 
Jones (1895) has observed the branching forms previously de- 
scribed by several authors, and states that they are only found upon 
the surface of culture media where there is free access of oxygen. 
He concludes that the tubercle bacillus does not form endogenous 
