1920] 
CHAMBERS—BACTERIAL INHIBITION BY METABOLIC PRODUCTS 255 
some new ideas on sugar relations and fermentation. They 
worked with Bacillus coli in bouillon containing varying amounts 
of dextrose. With less than .4 per cent dextrose the sugar 
was all removed in 24 hours and the cultures were viable after 
10 days, while with .4 per cent or over the cultures were sterile 
in 6 days. They reported that fermentation with gas com- 
menced at the time multiplication of the organisms ceased, that 
acid production started at the same time, and that more than 
one-half the total acid is produced in 1 hour. 
From the literature reviewed it would appear that a corre- 
lation of growth curves and Py curves, with frequent observa- 
tions during growth, rather than a study of final hydrogen ion 
concentration, would add to our knowledge of metabolic changes 
in hydrogen ion concentration and of inhibition during growth. 
'TECHNIQUE 
The experimental work was planned on the basis of a corre- 
lation of the growth of the bacteria with the changes in the 
hydrogen ion concentration of the media produced during growth. 
The technique was uniform throughout to make all results com- 
parable. Cultures were grown in Florence flasks of 500, 1000, 
and 2000 ec. capacity, filled to one-half their capacities for the 
initial volume of media to insure a uniform and maximum sur- 
face. The basic bouillon for all the cultures, designated plain 
bouillon through the text, consisted of 2.5 per cent bacto-beef 
and 1 per cent bacto-peptone made up with distilled water 
according to the Digestive Ferments Company circular of De- 
cember, 1916. This plain bouillon forms the basis for the 
different dextrose media, with a few exceptions which are noted 
in the data. 
A eulture of Bacillus coli, culture FG, kindly furnished from 
the Dairy Division, United States Department of Agriculture, 
was used throughout the experimental work with one excep- 
tion, in which Bacillus aerogenes, culture VE from the same 
laboratory, was substituted. 
To avoid the lag phase, transfers from stock agar were grown 
through two successive cultures of plain bovillon, and the inocu- 
lation was made from the second culture between 6 and 10 hours, 
during its period of logarithmic increase. A uniform tempera- 
