208 BOTANICAL GAZETTE [MARCH 
From the interesting results just cited, it was deemed important 
to ascertain if, contrary to the opinion of Loew and Aso,3 physio- 
logically balanced solutions are necessary for bacteria as they have 
been found to be for plants and animals, and if the behavior of 
_ bacteria toward completely balanced solutions is in full accord with 
that of the other classes of organisms. Accordingly, seven series of 
experiments were carried out, in which were employed upward of 
thirty solutions of different composition. In order to have the 
results strictly comparable, the average of several determinations in 
each case is inserted in the tables. It may be said that the duplicates 
showed very close agreement for ammonification cultures. The 
technique employed in these experiments was in general the same as 
that described in my former experiments above cited. The cultures 
were incubated in Erlenmeyer flasks of 250°° capacity for 2.5 days, 
at the end of which time the ammonia was determined. The solu- 
tions in each flask consisted of the constituents described under each 
in the tables, and, in order to provide uniform surfaces of aeration, 
were reduced to a bulk of 1o0°° in each flask after the salts were 
combined in the proportions given. 
SERIES I 
The object here was to compare pure solutions of NaCl and KCl 
and combinations of them with MgCl, and CaCl, respectively 
(which combinations have been shown to be beneficial in the experi- 
ments with binary solutions) with a blank solution of peptone in 
distilled water and one of peptone in tap water. The results are 
given in table I. 
In this series, as well as in former experiments, the salt mixtures 
which contained NaCl as the predominant salt always seemed to give 
better results, and it was decided therefore in the following series to 
make extensive use of the NaCl as a basis for all artificial solutions. 
We see from the table that the best results obtained with the salt 
solutions was in solution 3, as was the case in the experiments with 
binary solutions, but it will also be noticed that the blank peptone — 
solutions in both tap and distilled wator gave very much higher 
results than even solution 3. The depressing effect seen in the tap 
5 Bull. Coll. Agric. Imp. Univ, Tokyo 7: 35 5- 1907. 
