... CAUSE.—The direct cause of tuberculosis is Koch's Bacillus tuberculosis. This is a slender, rod-shaped microorganisms (Fig. 88) occurring in the diseased tissues, feces and milk of a tubercular animal. It belongs to that small group known as acid-fast bacteria. The tubercle bacillus is not really destroyed by external influences, and ... — Common Diseases of Farm Animals • R. A. Craig, D. V. M.