310 



VETERINARY BACTERIOLOGY 



In the United States it is rarely encountered on the western ranges, 

 but is relatively common in dairy and beef herds in other parts 

 of the country. Whenever swine are allowed to follow tuberculous 

 cattle, they commonly become infected. The same is also true 

 when they are fed upon unpasteurized milk from tuberculous 

 animals. Tuberculosis occurs rarely in the horse. Sheep have 

 been reported as tuberculous, but the disease is certainly rare; it 

 is probably frequently confused with pseudotuberculosis or caseous 

 lymphadenitis in this animal. Tuberculosis in domestic fowls is 

 known to occur in many European localities, and in the United 

 States has been reported from Oregon, California, and New York. 



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Fig. 125. Bacillus tuberculosis in 

 human sputum. Note the slender 

 beaded character of the rods (X 

 1000) (Giintherj. 





Fig. 126. Bacillus tuberculosis, 

 human, mount from glycerin agar 

 (Frankel and Pfeiffer). 



Morphology and Staining. B. tuberculosis is a slender rod, 

 frequently somewhat bent, with rounded ends. It varies from 

 0.2 to 0.5 by 1.5 to 3.5 ^, and sometimes longer. Frequently the 

 protoplasm takes the stain irregularly and gives a beaded appear- 

 ance to the cell. No spores or capsules are produced. The organ- 

 ism is non-motile. Branched and elongated forms resembling 

 somewhat the actinomyces are sometimes observed. It is probable 

 that these are involution forms, although some authors chiim I linn 

 to be developmental forms instead. The organism stains with 

 difficulty, but when once stained, is acid-fast. It is possible that 



