192 SCIENCE PROGRESS 



The attitude of suspicion and neglect towards disease in 

 plants attributed to bacteria was very general up to about 

 the year 1896 and is the more surprising when we consider the 

 enormous interest and enthusiasm created by the researches 

 and discoveries of Pasteur, Koch and other workers in the 

 domain of animal pathology. No doubt the human interest 

 involved in the latter case accounted for much and the great 

 names associated with such investigations overshadowed to 

 some extent the important labours of the earlier botanists. But 

 it is necessary to remember that valuable work was done in the 

 study of bacteria by Cohn as early as 1850, and that it was the 

 persevering and brilliant researches into the life-histories of 

 parasitic fungi, by botanists such as the Tulasnes, Cohn, Brefeld 

 and de Bary which laid the foundation of our knowledge of both 

 animal and vegetable pathology. 



Cohn was one of the earliest workers in bacteriology and we 

 must certainly acclaim him the real founder of this branch of 

 mycology and acknowledge that he has never been accorded his 

 true place in the history of the development of pathological 

 research. It was Cohn who first advanced the theory of the 

 plant nature of bacteria which formerly were known as Vibriones 

 and from the year 1868 onwards he continued vigorously to 

 prosecute his researches upon these micro-organisms. His 

 work was of supreme importance and influenced in great measure 

 the methods of scientific study of medicine, which at that time 

 began to look for the causes of disease through a microscopic 

 investigation of bacteria. He was for long the source of inspira- 

 tion to many of the younger men who were eagerly treading the 

 new path in biological research then opening before them. 

 Koch owed much to his association with Cohn ; all his training 

 was gained under him in the botanical laboratory at Breslau 

 and, as I have been reminded by Sir William Thistleton-D3'er, 

 they are Cohn's drawings which illustrate the publication by 

 Koch of the first proof of any disease of the higher animals due 

 to a specific bacterium. This account of his researches on the 

 life-history of the Bacillus autJiracis appeared in the Beitrdge 

 zur Biologic dcr Pflanzen in the year 1876. 



In the published work of Mitscherlich in 1850 which 

 announced to the Academy of Berlin his discovery of the 

 fermentation of cellulose, we find one of the earliest stages in 

 our knowledge of the part played by bacteria pathogenic to 



