Bacillus tuberculosis

Germ whose diameter is about 이어 of an inch and whose length varies up to ab. o of an inch. It breeds in the ti ues of warm-blooded animals, and there produces tubercles that gradually break up and pa their germ contents into the blood, so that the disease often becomes. transported to other organs. When the tubercle breaks into an air pa age in the lungs, the germs are coughed up, and when dried are taken up by the air as dust, and so may infect other animals or man. The diagnosis of this germ by microscopic examination is usually difficult, especially when present in milk, unle so abundant as to average one germ per drop. To prove its presence it is needful to subject the sample (of sputum from a consumptive, e.g., first dried on a gla slide and heated), to a prolonged action of a powerful aniline dye, like fuchsin or gentian violet, at ordinary temperatures, and at 212° F. a few minutes may suffice. Then the slide must be washed in 30 per cent nitric acid until apparently decolorized. This takes the color out of ordinary bacteria, but not out of the tubercle germ. Washing in water follows, and usually a staining with a complementary color of the other objects on the slide is practiced, to help in seeing the germs. A magnifying power of over 600 diameters is needed to see them satisfactorily.