CAUSATION OF DISEASE 27 



He showed the cause to be a protozoan which had been seen 

 previously by Cornaha and described by Nageli under the 

 name Nosema bombycis and devised preventive measures. 

 This was the first infectious disease shown to be due to a proto- 

 zoan. In 1866 Rindfleisch observed small pin-point-like 

 bodies in the heart muscle of persons who had died of wound 

 infection. Klebs, in 1870-71, published descriptions and 

 names of organisms he had found in the material from simi- 

 lar wounds, though he did not establish their causal rela- 

 tion. Bollinger, in 1872, discovered the spores of anthrax 

 and explained the persistence of the disease in certain dis- 

 tricts as due to the resistant spores. In 1873 Obermeier 

 observed in the blood of patients suffering from recurrent 

 fever long, flexible spiral organisms which have been named 

 Spirochoeta obermeieri. Losch ascribed tropical dysentery 

 to an ameba, named by him Amcsba coli, in 1875. Finally, 

 Koch, in 1876, isolated the anthrax bacillus by means of gelatin 

 plates (first used by Emil Chr. Hansen in his studies on yeast), 

 worked out the life history of the organism and reproduced 

 the disease by the injection of pure cultures and recovered 

 the organism from the inoculated animals, thus establish- 

 ing beyond reasonable doubt its causal relationship to the 

 diseasi. This was the first instance of a bacterium proved 

 to be the cause of a disease in animals. Pasteur, working on 

 the disease at the same time, confirmed all of Koch's find- 

 ings, though his results were published the next year, 1877. 

 Bollinger determined that the Actinomyces bovis {Strepto- 

 thrix boms) is the cause of actinomycosis in cattle in 1877. 

 Woronin in the same year discovered a protozoan (Plasmo- 

 diophora brassicce) to be the cause of a disease in cabbage 

 plants, the first proved instance of a unicellular animal caus- 

 ing a disease in a plant. In 1878 Koch published his 

 researches on wound infection in which he showed beyond 

 question that microorganisms are the cause of this condi- 

 tion, though Pasteur, in 1837, had suggested the same thing 

 and Lister had act^d on the theory in preventing infection. 

 These discoveries, especially those of Koch, immediately 

 attracted world-wide attention and stimulated a host of 

 workers, so that within the next ten years most of the bac- 



