108 EXPERIMENT STATION RECORD. 



ment of tuberculosis in man, and emphasizing that the chief danger 

 to man is from the human type, Avhich does not affect cattle. His 

 conclusion that the transmission of the bovine disease to man takes 

 place rarely or not at all through the milk or flesh of diseased animals 

 met with much opposition, and has not been generally accepted; but 

 he held to it and at the International Congress on Tuberculosis in 

 1908, which met in this country, he reiterated this view. 



In 1800. Koch announced his discovery of tuberculin (old tuber- 

 culin), and expressed the belief that in it a specific cure for tuber- 

 culosis had been found. This aroused the greatest interest through- 

 out the world, and speedily became the subject of widespread investi- 

 gation into its curative and diagnostic properties. His " new tuber- 

 culin " was brought forward in 1897. 



After his masterly work on tuberculosis, Koch Avas naturally looked 

 upon as the man most likely to solve the complicated problem con- 

 nected with cholera epidemics. In 1883 he was sent to Eg}pt on this 

 quest, the disease then threatening to invade Europe; and from there 

 he proceeded to India to continue his studies. The result was the 

 discovery of the comma bacillus as the cause of cholera, a classic 

 investigation recognized as one of the greatest triumphs of his life 

 work. On returning to Germany in 1884, he was rewarded for his 

 labors by a gift of 100,000 marks from the government, and the fol- 

 lowing year was appointed a professor at the University of Berlin 

 and director of the new Hygienic Institute. This position he occu- 

 pied until 1891, when he was appointed director of the newly founded 

 Institution for Infectious Diseases in Berlin. 



Koch's investigations on rinderpest in Africa in 1896 resulted in 

 the discovery that cattle can be immunized against the disease for a 

 period of several months, through the injection of bile taken from 

 animals which have been sick with the disease for six or eight days. 

 Other investigations followed on bubonic plague, surra, African coast 

 fever, and malaria. His work upon the latter led to his recommenda- 

 tion of the preventive administration of quinin to people as a means 

 of destroying the plasmodia in infected individuals, or preventing 

 their development, in malarial districts, and thus ridding a com- 

 munity of malaria. Koch also studied various protozoan diseases in 

 German East Africa in 1901, and in 190G he visited the interior of 

 Africa to study sleeping sickness and means for its prevention, meet- 

 ing, however, with only partial success. 



Through the development of exact methods of investigation which 

 resulted in placing bacteriology on the basis of an independent bio- 

 logic science Koch made possible the present advanced state of our 

 knowledge of infectious diseases. That he himself contributed much 

 to this knowledge will be evident from the record of his remarkable 

 activity, which was crowned with such large measure of success. In 

 the discoverv of the tubercle bacillus and the fact that tuberculosis is 



