106 BOTANICAL GAZETTE [aucust 
quent experiments of OsTERHOUT on the higher plants. It was indeed — 
the insight of the latter investigator which led him to conclude some ~ 
time ago that a proper understanding of physiologically balanced 
solutions in relation to plants and to soil bacteria would render the 4 
control and successful cultivation of alkali lands a much simpler — 
matter than it has been, and this will undoubtedly prove true in the ~ 
near future. 
In the selection of an ammonifier which could be used uniformly 
throughout all the experiments, the writer was guided by the work of 7 
MARCHAL (15), to whom indeed we owe what little knowledge we ~ 
have of the physiology of ammonifiers. Among the best ammonifiers 4 
found by that investigator were B. mycoides, which changed 46 pet — 
cent. of nitrogen into ammonia in a given time, Proteus vulgaris (36 — 
per cent.), Sarcina lutea (27 per cent.), and B. subtilis (19 per cent). 
Since the last form is easily isolated and cultivated and is a strong 
ammonifier, it was decided to use it in the following experiments. It 
is more than probable that the same relative results will be obtained 
with any ammonifier; this, however, will be tested in other expéer- 
ments now contemplated by the writer. The pure culture of B. 
subtilis employed for inoculation through all the series of experiments 
was obtained from soil from Auburn in the foothill fruit region © 
California. 
The salts tested were the chlorids of sodium, potassium, calcium, 
and magnesium. Only chemically pure salts were used, after sub- 
mitting them toa flame test. Molecular or bimolecular stock solutions 
in distilled water were made, from which the requisite amounts were 
taken for the various concentrations. Witte’s peptone was the nitro- 
genous substance used for the ammonification, of which 1 per cent. 
solutions were employed in the tests for the single salts and 0.75 Pe 
cent. in the binary solutions. The method of inoculation employed W4S 
as follows: Inoculation is made from peptone agar slope of B. sub- — 
tilis into a sterile 100° portion of 1 per cent. peptone in a 25% — 
Erlenmeyer flask. This is incubated for forty-eight hours at 28° Cs 
at the end of which time the membrane that forms on the surface of 
the culture is precipitated by slight shaking, and then by tilting the 
flask to one side and carefully setting it down again, the liquid cove™ 
ing part of the bottom of the flask remains free from membranous 
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