[Vor. 7 
258 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
EXPERIMENTAL DATA 
As a starting point for the experimental work and as a basis 
for comparison of inhibitory action, one culture in plain bouillon 
and one culture in this bouillon with 1 per cent dextrose added 
were inoculated with equal numbers of Bacillus coli from the 
same culture. The resulting growth (expressed in numbers of 
bacteria per cc.), and the hydrogen ion concentration of the 
media (expressed in P4) are recorded in table 1. The compari- 
son is more strikingly shown in fig. 1, in which the growth curves 
are plotted from the logarithms of numbers of bacteria per cc. 
as given in table r. A comparison of the hydrogen ion curves 
shows a rapid production of acid from dextrose, attaining Py 4.8 
in 36 hours, but a slower production of alkali in the plain bouillon 
with the exception of the short acid break at the beginning 
of the curve. Growth in the dextrose bouillon is more rapid in 
12 hours than in the plain bouillon but the maximum is reached 
in 20 hours, 281,000,000 bacteria per cc. when the P, is 5.1, 
and the decline is then very abrupt, terminating in sterility of 
the culture in 144 hours. In the plain bouillon, the maximum 
is reached in 48 hours, 609,000,000 bacteria per ce., with a Py 
of 7.6. However, after 75 days, although a P, of 8.7 is attained, 
there are still 7,500,000 viable bacteria per cc. in the culture. 
Apparently, then, the more intense inhibition is found in the 
dextrose rather than in the plain bouillon. 
If a bacterial *autotoxin," or any inhibitory action such 
as Chesney found with pneumococcus in plain broth, is produced 
by Bacillus coli, it would seem, from the results given in table 1, 
to be associated with the dextrose bouillon and not with the 
plain bouillon. A series of cultures in a 1 per cent dextrose 
medium were observed for the purpose of determining any 
variation in inhibitory action during growth and death. The 
results are given in table 11 and illustrated in fig. 2. Flask 1, 
the parent culture, contained the same 1 per cent dextrose 
bouillon as Culture 2 of table 1. Subcultures of 200 cc. each 
were removed from the parent cultures at the times indicated, 
commencing before the point of maximum growth was reached 
and covering a range well into the period of rapid death. The 
reaction of the subcultures was readjusted to approximately 
neutral with sterile N/1 NaOH to eliminate the acidity factor, 
