210 BOTANICAL GAZETTE [MARCH 
by B. subtilis in peptone solutions. The solutions were prepared 
as shown in table II, and the ammonia determined with results as 
given. 
Comparing the first five solutions with solution 6, we find that we 
have not yet arrived at what might be termed a balanced solution. 
Some salt mixtures of three salts do not give as good results as solu- 
tion 6, while solutions 3 and 4, which appear to be better than the 
former, are not sufficiently near the peptone water cultures (see 
table I) to allow them to stand without further experiments as the 
optimum solutions. None the less, it is plain that solution 3 1s 
approaching the balanced solution. 
SERIES II 
From the results just given it was thought that the addition of — 
another salt to the mixtures of three salts might tend to make them 
TABLE III 
ALL” QUANTITIES GIVEN REFER TO CUBIC CENTIMETERS OF 0.35 ™ SOLUTIONS 
PEPTONE CONTENT 0.91 PER CENT. 
: as NH; formed 
Number Culture solution n cultures, in mg 
19 - 37 
23.39 
wn 
at —_t  , 
~ 9 
ouwo 
4 
isin] ~ 
Q2o9 
n oa aa 
ww ee en™=" 0 00S 
NO 
cl 
~I 
JL 
6 j too NaCl 
ey eras jo MxG, 
approach still closer than did solution 3 of the last series the optimum 
solution. There were prepared, therefore, solutions containing 
