BACILLUS OF TUBERCULOSIS. 299 
authorities in adopting the necessary hygienic measures 
to stamp out tuberculosis entirely; but, judging from 
the results which have already been obtained in reducing 
the mortality from this dread disease, we have reason to 
believe that in time it can be completely controlled. 
The Tubercle Bacillus of Cattle and its Relation to 
Human Tuberculosis. Among the domestic animals 
tuberculosis is most common in cattle. On account 
of the milk which they provide for our use, and which 
is liable to contain bacilli, the relation of these to human 
tuberculosis is a matter of extreme importance. 
The chief seat of the lesions is apt to be the lungs 
and with them the pleura; less often the abdominal 
organs and the udder are affected. In pigs and horses 
the abdominal organs are most often involved, then the 
lungs and lymphatic glands. In sheep and goats tuber- 
culosis is rare. The bovine bacillus, as the most im- 
portant of the group, will be alone considered here. 
The bacilli derived from cattle are on the average a 
little shorter and straighter than the average human 
bacillus; but there are many derived from cattle exactly 
similar to those derived from man in size, shape, and 
staining. In guinea-pigs, and especially in rabbits, the 
bovine bacilli are more virulent than those from human 
sources. Animals infected with the bacilli from cattle, 
as well as those from the other domestic animals, react 
to the tuberculin test. All these bacilli are, therefore, 
undoubtedly from the same original stock, and at 
first glance we might consider it unnecessary to prove 
that those derived from cattle were capable of causing 
human tuberculosis. There are facts, however, which 
tend to make us doubtful of the extent to which this 
infection takes place. As we investigate we find that 
