TIMOTHY AND OTHER GRASS BACILLI. 319 
TIMOTHY AND OTHER GRASS BACILLI. 
On various grasses, in cow’s manure, in butter, and in 
milk, there have been discovered a number of varieties 
of bacteria which have more or less of the characteristics 
of the tubercle bacillus. Some of them are as difficult to 
stain and as resistant to decolorizing action of mineral 
acids and alcohol as the tubercle bacillus found in man. 
Many of them are of the same general size and shape as 
the tubercle bacillus, and, strangely enough, produce 
in animals small diseased areas, which not only macro- 
scopically but also microscopically resemble miliary 
tubercles due to the tubercle bacillus. They, however, 
are entirely different in their culture characteristics, 
producing in twenty-four to forty-eight hours on ordi- 
nary culture media moist, round colonies of an eighth 
to a quarter of an inch in diameter, and of a more or 
less intense pink color. In animals they produce only 
localized lesions, causing death only when injected in 
large numbers. The injected animals are unaffected 
by tuberculin injections. The chief interest which 
these bacilli have for us is the possibility of confusing 
them with the tubercle bacilli. This danger is always 
present in milk, for the grass bacilli find so many 
means of gaining entrance to it. In the examination 
of dust, healthy throat and nose secretions, etc., the 
simple microscopical examination might lead to error. 
They can be separated from tubercle bacilli by in- 
oculating animals, and then if they show any infection, 
injecting tuberculin, when if infected with tuberculosis 
they will die, but if by grass bacilli they will show 
no reaction. Cultures from the lesions will also show 
on ordinary media pink colonies if grass bacilli are 
present, and no growth if only tubercle bacilli. 
