Koch’s epochal work on the etiology of traumatic infectious disease established his reputation. He inoculated animals with material from various sources and produced six types of infection, each due to microorganisms. He carried these infections through several generations of animals. These experiments determined the role of bacteria in the etiology of wound infections and demonstrated for the first time the specificity of infection. This work also contains the first explicit statement of the criteria implicit in Henle (See No. 2533) on contagion, which later became known as Koch’s postulates. See also Nos. 2331 and 5167. English translation, New Sydenham Society, 1880.