1 -\ FKCT I \'1C GR A N U L{ )M ATA . 



545 



culosis is not common in the L'nited States, ur at least only a 

 few cases have been reported. Tuberculosis is usually found in 

 those horses and mules that have been fed on tubercular cows' 

 milk. 



Tuliercnlosis of sheep is ver\' rare and the disease is still 

 less common in goats. 



Di'g" and cat tu])erculosis is not uncommon and is usually 

 obser\e(l in jiets of tul^ercular humans, although barn cats, es])e- 

 ciall\- those fed milk from tubercular cows, frequently become 

 tubercular. (A dairv was recenth- inspected in which (js^f of 

 the Cows were tubercular and on autopsv three barn cats also 

 were found to be afTected in a like manner.) 



Tuberculosis of fowls is more prevalent in the United States 



193 —Bacterium Tuberculosis Bovine. Pus showing 



shreds. 



and lissu>- 



than is urdinarilv suspected, although the percentage u{ aflected 

 birds is difficult of determination because there is at present no 

 official inspection of fowls. 



Etiology — Tul)erculosis is caused by the liacterium tuberculo- 

 sis. Tliis bacterium has rounded ends and is fre(|uently slightly 

 t^ent. It varies from 2 to 5 microns in length and from .3 to ..^ 

 in width. (These bacteria may appear as long, delicate, mycelial 

 threads, branching forms, or even as a ray like fungoid growth, 

 the form depending upon the environment. The pleomorphism 

 of this micro-organism has caused some doubt as to its classifica- 

 tion as a bactenum.) The Bacterium tuberculosis may occur 

 singlv or in pairs, and it is not uncommon to find several lying 



