The tubercle bacillus was implicated in 1882 by Koch as the etiologic agent responsible for tuberculosis. The postulates, probably his best remembered contribution to the concept of infection and disease, were not published until two years later. Koch developed bacteriologic techniques when none existed and thereby exposed the mysteries of infection. The logical conclusions that evolved from his contributions typify the brilliance of his scientific reasoning. The bud of bacteriology was just beginning to burst, and the attention of many scientists was focused upon this productive new area in medicine. To be sure, tuberculosis had been studied intensively for a long time, but the chain of evidence between identification of the suspected organism and reproduction of disease in animals had not been completed.
When a void in scientific knowledge became apparent, Koch endeavored to fill it. He developed a new type of culture medium based upon the solidification of gelatin;
THE POSTULATES OF ROBERT KOCH. JAMA. 1961;175(11):1003-1005. doi:10.1001/jama.1961.03040110067019