TUBERCULOSIS IN CATTLE, yt 25° 
out of the mouth. The bacilli that thus pass through the 
stomach may eventually serve for a secondary infection in the 
alimentary canal of the animal, or they may pass away in the 
excrement. The boots of the attendant will now distribute 
the excrement from stall to stall, and even infect with the bacilli 
the hay which the cows are to eat. Anyone familiar with the 
habits of the attendants of cattle will easily see how the disease 
may be thus distributed by the excrement of infected animals. 
A second source of elimination of the bacilli from the lungs 
has recently been discovered and must not be neglected. It 
has been shown by recent experimental work that one of the 
common methods of the distribution of germs is in the small 
particles of vapor which pass into the air from the mouth or 
lungs of an‘individual when coughing. Ordinary breathing 
has for a long time been known to have no power to distribute 
bacilli, since they cling to the moistened surface of the mouth 
and throat; but the most recent experiments have shown that 
in the case of coughing, minute particles of water are dis- 
charged from the mucous membranes of the mouth and throat 
and are blown into the air, where they float around for a time: 
in the form of an imperceptible mist. They may now be dis- 
tributed for long distances by the currents of air, even in a 
closed place, like a cow stall. Ifthe air thus becomes charged 
with the bacillus-laden drops of moisture, it is perfectly clear 
that healthy animals, even if some distance away, in the same 
apartment may breathe these particles of moisture into the 
lungs and thus obtain infection. The bacilli from all these 
sources will adhere to the rough surfaces of the cow-stall, and 
may necessitate frequent disinfection. 
Another method by which the animal may convey the 
bacilli is by actual contact with other animals, especially if the 
animals bring their noses together or if they cough in each 
others faces. If they are eating out of the same mass of hay, 
one may infect the food with the bacilli from its mouth and 
the other individual swallowing the hay may thus become 
infected. 
That the milk of a tuberculous animal may under certain 
conditions contain the bacilli is demonstrated beyond ques- 
tion. It is clear that the calves sucking milk from a tuber- 
culous mother may from this source obtain the bacilli, which 
start an infection in their own bodies. If such milk is carried 
to a creamery and run through a separator, the skim-milk 
will contain many of the bacilli. Now, by the ordinary cus- 
