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 



