[Vol. 10 

 62 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



196. Bacillus coli and B. vulgatus were the only organisms 

 vestigated that attacked and used dextrin and starch. The 1 

 ter, however, appears to have been able to break down both 



these substances more rapidly than it utilized the derived sug 

 (table xm). 



In respect to the amounts of carbohydrates actually utilized, 

 it will be noted upon reference to table xiv that with the several 

 microorganisms under observation (excepting the yeast) the 



small as compared with 



mjrms 



of 



gatus on fructose is the only one where the actual amount con- 

 sumed approaches 50 per cent of the total amount of the sugar 

 provided. The different strains of Bacillus atrosepticus con- 

 sumed only about 10 to 20 per cent of the available supply of 

 carbohydrates. Bacillus coli utilized about 30 per cent, and B. 

 vulgatus about 40 per cent of the supply. In the light of these 

 findings it would appear that the usual recommendation relative 

 to the amount of carbohydrate that should be supplied in a nu- 

 trient medium was a most liberal one. Bacillus coli and B. vul- 

 gatus are usually thought of as being particularly active in fer- 

 menting certain saccharides, especially when compared to most 

 plant pathogens. As it is possible that there are numerous bac- 

 terial species for which the optimum sugar concentration is 1 

 per cent or even more, it is doubtful if a less liberal recommen- 

 dation should be made until the whole matter has been more 

 extensively investigated. However, in the light of these findings, 



as well as those of Besson, Ranque and Senez (19), Chambers 

 ('20), Wolf and Foster ('21), and others, it appears that B. coli, 

 also some plant pathogenic bacteria, require a less amount of 

 sugar than 1 per cent for optimum development. Besides, there 

 is abundant evidence which indicates that most plant pathogenic 

 bacteria require a very much lower sugar concentration than 1 

 per cent (cf. also sugar consumption by B. atrosepticus, table 

 xiv). 



Further evidence of the similarity of the several strains of the 

 blackleg bacillus employed throughout these investigations is 

 brought out in tables x-xni. 



