1923] 



JENNISON — POTATO BLACKLEG 51 



the actual amount of sugar (as glucose) left was calculated by ref- 

 erence to Shaffer's ('14) table of copper-glucose values. In order 

 to determine consumption of the non-reducing carbohydrates in use, 

 i.e., sucrose, dextrin, and starch, it was necessary to accomplish inver- 

 sion by heating in the presence of an acid (see "Methods, 7 ' p. 47, et. 

 seq). This having been accomplished, the procedure was exactly as 

 outlined above. 



The control tubes containing the several carbohydrate broths were 

 handled in exactly the same manner as the cultures, except for in- 

 oculation, and were a component of each experiment. 



EXPERIMENTAL DATA 



The data relative to carbohydrate utilization are presented in 

 tables ix-xiii. Where practicable the amounts of the test 

 substance consumed are given in mgms. of the carbohydrate sup- 

 plied. The most complete data are, for obvious reasons, given in 

 terms of mgms. of glucose. The writer believes that the figures 

 are reliable to the extent of showing relative differences in carbo- 

 hydrate utilization as well as the amounts of the test substances 

 consumed by each of the several species and strains of the micro- 

 organisms employed. 



A slight error in the sugar data presented may have developed, 

 due to the fact that it was necessary to make interpolations be- 

 tween figures available in tables ix-xm, in order to determine 

 the sugar equivalent of the copper values obtained from my own 

 permanganate titration data.. The following figures and state- 

 ments are presented to illustrate the methods and the calcula- 

 tions employed in obtaining the sugar values presented in the 

 above-mentioned tables. The specific case of Bacillus coli in the 

 presence of glucose is selected for this illustration. The 10-cc. 

 sample of the culture taken for treatment with Fehling's and 

 subsequent titration represented (as in all other cases) 1.666 cc. 

 of the original 10-cc. sugar broth in which the organism was cul- 

 tivated. It was not necessary to account for possible loss due 

 to evaporation, since the cultures were made up to 60 cc. before 

 sampling. 



Having determined the number of cc. of permanganate for 1 

 cc. of the original culture solution as 4.15, then the number of 

 mgms. of copper is represented by 13.2, determined by multiply- 

 ing 4.15 by the factor 3.18 (it was previously determined that 1 

 cc. of N/20 permanganate is equivalent to 3.18 mgms. copper). 



