Studies on Physiology of Some Plant Pathogenic Bacteria 
39 
When the data in Table 10 are contrasted with those in Table 6, it will be 
seen that they differ mainly in the fact that the greater concentrations of pep¬ 
tone tend to decrease the rate of change in reaction. This modifying influence 
exerted by buffer materials is entirely in accord with previously recorded ob¬ 
servation on Streptococcus liemolyticus, B. coli, and other members of the 
colon-typlioid-dysentery group. 
Experiment VII—The Relation of Initial Hydrogen Ion Concentration to 
The Final Level of Acidity Produced by Bacillus Carotovorus, 
Bacterium Glycineum and B. Sojae in 2 Per Cent Sac¬ 
charose Bouillon 
The saccharose bouillon used in this experiment was adjusted to the four 
pH values, 5.5, 6.2, 7.2, and 8.0 before inoculation with the several organisms. 
The cultures were incubated at 28°C. and the reaction was determined at 
24-liour intervals with the results expressed in Table 11. 
Table 11.—Relation of Initial to Final pH Concentration in 2 Per Cent 
Saccharose Bouillon 
Organism 
Initial 
pH 
Age in Days and pH Concentration 
» 
Days 
1 
2 
3 
4 
5 
6 
7 
pH 
pH 
pH 
pH 
pH 
pH 
pH 
Bacterium glycineum - -- 
5.5 
5.5 
5.4 
5.2 
5.1 
5.1 
5.1 
5.1 
6.2 
6.2 
5.5 
5.3 
5.2 
5.2 
5.2 
5.2 
7.2 
7.2 
6.4 
5.6 
5.4 
5.4 
5.4 
5.4 
8.0 
8.0 
7.4 
6.8 
6.6 
6.2 
6.0 
6.0 
Bacterium sojae__ - - - 
5.5 
5.5 
5.5 
5.3 
5.3 
5.2 . 
5.2 
5.2 
6.2 
6.2 
6.2 
5.8 
5.5 
5.4 
5.4 
5.4 
7.2 
7.2 
7.2 
6.8 
6.2 
6.0 
5.8 
5.8 
8.0 
8.0 
7.8 
7.4 
7.3 
7.2 
7.0 
6.8 
Bacillus carotovorus .. 
5.5 
5.2 
5.2 
5.2 
5.1 
5.1 
5.1 
5.1 
6.2 
5.4 
5.2 
5.2 
5.2 
5.2 
5.2 
5.2 
7.2 
5.4 
5.2 
5.2 
5.2 
5.2 
5.2 
5.2 
8.0 
5.4 
5.4 
5.4 
5.4 
5.4 
5.4 
5.4 
A maximum period of lag following transplantation occurred in all cultures 
with an initial of pH 5.5. By the end of four days, B. carotovorus had reached 
its final reaction which differed by 0.3 pH between the initial extremes. B. 
glycineum and B. sojae had not completed their activity within seven days, but 
it is clearly evident that a curve of their reaction resultants would not be a 
line parallel to the abscissa. Just as in the case of B. Welchii and B. sporo- 
genes as shown by Wolf and Harris (21) and B. coli as shown by Wyeth (25), 
there is a definite relationship between the initial and the final pH. The 
highest final levels are attained by cultures with the highest initials and the 
lowest finals by those with lowest initials. It appears probable also that the 
reaction resultants reached from any point between the two initial extremes, 
pH 5.5 and pH 8.0, would fall in a straight line passing between the two ex¬ 
tremes of final reaction, i. e., pH 5.1 and pH 5.4 in the case of B. carotovorus. 
