148 UNIVERSITY OF WISCONSIN STUDIES 
nitrites. The nitrates were unaffected. This, except for the 
decrease in the nitrites, follows very closely what was found 
under similar conditions for B. mesentericus var. ruber in 
pure cultures. The cultures, however, showed a considerable 
overgrowth of B. subtilis. 
B. subtilis and B. pyocyaneus.—In both sets of flasks the 
bacteria grew practically equally well. 
In the aerobic flasks the free ammonia aud the organic 
nitrogen were decreased, while the nitrites and nitrates were 
both increased. 
In the anaerobic flasks the free ammonia was increased 
with a deercase in the organic nitrogen and nitrites. The ni- 
trates were unaffected. 
B. cloacae and B, mesentericus var. ruber.—B. mesenteri- 
cus var. ruber overerew B. cloacae in both sets of flasks. 
In the acrobic flasks the chemical action was more irreg- 
ular than was found for B. mesentericus var. ruber in pure 
culture, but in general coincided very closely to it. The most 
marked effect was on the nitrites and nitrates. The nitrates 
were decreased with an inerease in the nitrites. 
Tn the anaerobie flasks the action was much more typical 
of B. mesentericus var. ruber, the free ammonia being in- 
creased with a decrease in the organic nitrogen. The nitrates 
were decreased and the nitrites were inereased. 
B. cloacae and B. proteus.—The action of these bacteria 
was very irregular and typical of neither. This was true for 
both the anaerobic and aerobic flasks. 
The nitrites were generally inereased. Jn one experiment 
all of the nitrogen was reduced in amount. 
B. proteus and B. mesentericus var. ruber.—In the 
anacrobie flasks the tendeney was to decrease both the free 
ammonia and the organie nitrogen, while the nitrites and 
nitrates were increased, These results follow those obtained 
from B. proteus more closely than B. mesentericus var, ruber. 
The cultures showed a slight overgrowth of B. proteus in 
the anaerobic flasks. 
B. pyocyaneus, B. proteus, B. pyocyaneus and B. mesen- 
tericus var. ruber.—Neither of these gave results in either 
set of flasks. 
