2l8 BACTERIA 



pathogenic bacteria (streptococci and pneumococci) rapid soften- 

 ing occurs, with cavity formation, etc. Tubercles may develop 

 in any organ or tissue of the body. The lungs, intestines, 

 peritoneum, glands, larynx, spleen, and bones become infected. 

 The liver and pancreas seem to resist invasion more than other 

 organs. Bacilli are rarely found in the blood in tuberculous 

 diseases. They may, however, be found in the urine, in kidney 

 or bladder tuberculosis. Milk from tuberculous cows, with, 

 infected udders, often contains bacilli, and is certainly a means 

 of transmitting the disease. Cerebro-spinal fluid, in tuberculous 

 meningitis contains the bacilli. Bacilli may penetrate mucous 

 membranes, and not causes any local lesions, but infect distant 

 organs. Tuberculosis may be spread in the body in four ways. 

 Sputum may be swallowed and infect the intestines, by continuity, 

 by the lymph-stream, or by the blood; this may cause intestinal 

 ulceration and invasion of the peritoneum. If the bacilli reach 

 the blood-stream, the disease produced is generally acute miliary 

 in type. This is manifested by the formation of fine gray 

 tubercles. In tuberculosis of the lungs it is more than probable 

 followed skin inoculation, either by accidental or intentional 

 trauma that the bacilli are inhaled. Local tuberculosis has often 

 Tuberculous mothers may have tuberculosis of the genital tract, 

 and fathers, having tuberculous testes, discharge bacilli in the 

 semen. Placental transmission of the bacilli from mother to child 

 occurs rarely. 



Types of Tubercle Bacilli. It has been considered probable by 

 many observers that there are two types of bacilli, a human and a 

 bovine type. Theobald Smith was the first to advance this 

 theory. Koch has announced that the two types were totally 

 different, and that the human was incapable of infecting cattle, 

 and the bovine was not pathogenic for man. In view of the fact 

 that cattle are frequently tuberculous, and the bacilli are often' 

 found in the milk, it is important to know if the bovine type can 

 develop in man. Ravenel has shown that it is undoubtedly 



