BACTERIA AS PLANTS. 15 



gested their causal connection with fermentation 

 and disease, but it was because he for the first time 

 placed the subject upon a firm foundation by prov- 

 ing with rigid experiment some of the suggestions 

 made by others, and in this way turned the atten- 

 tion of science to the study of micro-organisms. 



After the importance of the subject had been 

 demonstrated by Pasteur, others turned their at- 

 tention in the same direction, either for the pur- 

 pose of verification or refutation of Pasteur's 

 views. The advance was not very rapid, however, 

 since bacteriological experimentation proved to be 

 a subject of extraordinary difficulty. Bacteria 

 were not even yet recognised as a group of organ- 

 isms distinct enough to be grouped by themselves, 

 but were even by Pasteur at first confounded with 

 yeasts. As a distinct group of organisms they 

 were first distinguished by Hoffman in 1869, since 

 which date the term bacteria, as applying to this 

 special group of organisms, has been coming 

 more and more into use. So difficult were the 

 investigations, that for years there were hardly 

 any investigators besides Pasteur who could suc- 

 cessfully handle the subject and reach conclu- 

 sions which could stand the test of time. For the 

 next thirty, years, although investigators and in- 

 vestigations continued to increase, we can find 

 little besides dispute and confusion along this 

 line. The difficulty of obtaining for experiment 

 any one kind of bacteria by itself, unmixed with 

 others (pure cultures), rendered advance almost 

 impossible. So conflicting were the results that 

 the whole subject soon came into almost hopeless 

 confusion, and very few steps were taken upon 

 any sure basis. So difficult were the methods, so 

 contradictory and confusing the results, because 



