376 AGEICULTUBAL AND INDTISTEISLL BAOTBEIOLOGY 



general the bovine bacillus is the most pathogenic, the 

 human next and the avian least except for birds. Inocula- 

 tion in guinea pigs with bovine bacillus usually leads to 

 death in less than 30 days, while those inoculated with 

 human bacillus will live for several months. Injection of 

 the rabbit with bovine bacillus usually kills the animal 

 within three weeks, while similar injection of the human 

 bacillus usually does not prove fatal for several months 

 and in some cases the animals may recover. Calves inocu- 

 lated with bovine bacilli succumb rather rapidly to the 

 disease, while similar inoculation with human bacilli pro- 

 duces only local lesions which eventually heal. 



In man tuberculosis is most common as a disease of the 

 lungs (so-called consumption). Next in frequency come 

 tuberculosis of the lymph glands of the neck (scrofula), of 

 the bones and joints (bone and articular tuberculosis), of 

 the covering of the brain (tubercular meningitis), abdom- 

 inal tuberculosis and occasionally tuberculosis of the skin 

 (lupus). In cattle the disease generally attacks the mesen- 

 tery causing the development of the so-called pearly disease 

 characterized by the nodules on the membrane lining the 

 peritoneal cavity. Tuberculosis of the lungs is also com- 

 mon. Frequently in the cattle the lymph nodes become 

 enlarged. Tuberculosis of the udder is sometimes noted in 

 tubercular cows. Swine generally show infections of the 

 lymph glands in the neck, frequently also abdominal and 

 pulmonary lesions. In the domestic fowl the tuberculosis is 

 in general abdominal, the lesions and nodules showing par- 

 ticularly in the liver and spleen and somewhat more rarely 

 in the lungs. 



Immunity. — Practicable methods of immunizing against 

 tuberculosis have not been developed although many at- 

 tempts have been made and there has been an immense 

 amount of systematic work done in this field. It is possible 

 to immunize cattle against bovine tuberculosis by injection 



