” 
212 BOTANICAL GAZETTE [MARCH 
_ were arranged and compared with solution 5 of the last series con- 
taining three salts and with a solution of peptone in distilled water 
and one in tap water. 
The large proportion of the potassium salt interfered with the 
beneficial action of the calcium in solutions 1 and 2, as can be seen by 
comparing them with solution 3, which differed from the others only 
in having less potassium and in consequence seems to approach quite 
closely the peptone solution in tap water, and also is far better than 
solution 4, which until now showed up as the most favorable solution 
of all the artificial salt mixtures employed. Solution 5 as before 
shows the optimum conditions, since there is neither high osmotic 
pressure nor any toxicity in it, to interfere by the ammonification 
by B. subtilis. 
SERIES V 
Since in the foregoing series we have been gradually approaching 
a balanced solution in some of the salt mixtures, it is appropriate to 
compare them now with sea water, both in its original and diluted 
forms, as well as with RINGER’s solution (which consists of 100 parts 
NaCl, plus two parts KCl, plus two parts CaCl,), and with a solution 
TABLE V 
ALL QUANTITIES GIVEN REFER TO CUBIC CENTIMETERS OF 9:35 m SOLUTIONS, 
EXCEPT AS EXPLAINED ABOVE 
‘ T ae 7 
Number Culture solution 28 pad lec 
too NaCl 
GON to MgCl, 25.88 
5 CaCl, J 
100 NaCl 
o KCl 
pee ns io MgCl, 28.42 
CaCl 
Ba: RINGER’S — 19.74 
Ce Re reed amb water 10.72 
ee ae Dilute ye basis 31-35 
Oe. Aviciats sea water (VANT’ 
Horr’s solution) 31.4! 
bi 
made up so as to constitute an artificial sea water (VAN’T Horr s 
solution). The natural sea water was obtained from Pacific Groves 
California, and by titration for chlorids was found to have a com 
