452 THE STOCK OWXEll S ADVISER. 



comes hard and gritty from the deposition of lime salt. If the 

 udder is affected yellow spots or tubercles are discernible on the 

 cut surface; the entire quarter is enlarged and hard, and the 

 lymphatic glands of the udder are usually tu'berculous. In the 

 intestines the morbid process is most marked at the lower end 

 of the ilium and in the caecum. The appendix is sometimes af- 

 fected; also the duodenum and rectum. The germs reach these 

 parts through infected milk or meat. The urino-genital tract 

 may also be a seat of tubercular infiltration. In the brain, the 

 masses vary in size from a hazelnut to a pigeon's egg, and com- 

 monly occur in the cerebral substance, especially at the base of 

 the brain. They are of a pale yellow color, and usually form 

 quite round globular tumors. Their surface is often seen to be 

 covered with minute gray nodules, which extend into the sur- 

 rounding tissue. 



If a tubercular mass be examined microscopically, it will be 

 found that those tubercles near the circumference of the diseased 

 area contain the largest number of active bacilli, and that these 

 germs are thus favorably situated to invade the surrounding- 

 tissues, or to be carried by the lymph or blood vessels to distant 

 parts of the body, and there set up the tubercular process. The 

 disease has prevailed throughout the old and new world. It is 

 much more prevalent in some races of cattle than others, and is 

 much more common in the milk than the beef breeds. The coun- 

 try in the vicinity of large cities contains a larger percentage of 

 tuberculous animals than more remote localities. It is not, how- 

 ever, the proximity of the cities which leads to the prevalence of 

 the disease, but the system of housing and caring for the animals 

 practiced in such districts. 



Tuberculosis is no't developed in every animal which inhales or 

 injects the germ, because all animals are not equally predisposed. 

 Close stalling, poor ventilation, feeding on innutritious food, and 

 all the influences of domestication predispose the animal to the 

 disease. Where these depressing causes exist, it is much easier 

 for tuberculosis to start and spread. But no matter how weak a 



