TUBERCULOSIS. 263 
they are normally subjected, and we must therefore conclude that 
its multiplication is confined to the bodies of animals. While it can 
flourish in the artificial media of the laboratory, when kept at 
special temperatures, it does not flourish in nature, outside the 
bodies of animals upon which it lives as a parasite. 
Animals Subject to the Disease. Besides living in man the 
organism can flourish in the bodies of cattle, hogs, dogs, cats, monkeys, 
rabbits, guinea-pigs, and some other animals. In all these it pro- 
duces very similar symptoms, differing slightly, of course, in the 
different animals. The characteristic feature of the disease is the 
production of tubercles swollen masses of tissue which eventually 
break down into a cheesy mass. These tubercles may appear at 
almost any part of the body. Of all the animals the guinea-pig is 
the most delicately susceptible to the bacillus. An extremely small 
infection will produce the disease in the guinea-pig, and for this 
reason these animals are used in experiments to test the presence of 
the bacillus. A little suspected milk inoculated under the skin of 
the guinea-pig will produce the disease inevitably, if only the smallest 
number of virulent germs are present. Besides these mammals a 
number of birds show a similar disease, with a similar bacillus 
present in the infected organs. The bacillus in birds is, however, 
in some respects, slightly different from that in men and cattle, and 
is frequently regarded as a different type of the organism. 
Most parasitic bacteria are able to grow only on certain parts of 
the body, diphtheria commonly in the throat, cholera in the intestine, 
etc. But the tubercle bacillus can live in almost any part. It is 
found in the intestinal organs, in the lymphatic glands, in the lungs, in 
the bones, in the joints, in the kidneys, in the skin, and, in short, 
almost anywhere. When occurring in the different organs in man 
it receives different names; consumption, scrofula, lupus, hip disease, 
nephritis are some of its common names. 
Resistance Against Tuberculosis. Although this organism 
can attack almost any part of the body, it is also certain that the 
body has a strong resisting power against it. It by no means follows 
that a person will take the disease because some of the bacilli find 
entrance into his body. On the contrary, as a general rule, they 
