116 BOTANICAL GAZETTE [AUGUST 
It is a significant fact that here again the maximum point on the 
curve nearly coincides with that of a similar curve obtained by 
OsTERHOUT (19) in his experiments with the same salts on root 
development in wheat, and exactly coincides in the case of a fungus 
(Botrytis cinerea); and though OsteERHOUT employed such widely 
varying concentrations as 0.12 m in the case of the wheat and 1.5 m 
in Botrytis, the maximum development was reached in a mixture of 
10° of the MgCl, solution (or 7.5°° for wheat) and 100°° of the 
NaCl solution, just as was the case in ammonification by B. subtilis. 
In his experiments on the eggs of Fundulus and the sea-urchin 
(Arbacia), Lors (10) found that in a mixture of 98°° 5n/8 NaCl 
and 2°¢ rov/8 MgCl, all the eggs of Fundulus form embryos, whereas 
in pure NaCl or MgCl, solutions alone no embryos would form, and 
even in a mixture of equal parts of the above-mentioned solutions 
75 per cent. of the eggs formed embryos. On the other hand, Ost- 
WALD (21) found in his work on the freshwater Gammarus that, so 
far from exercising an antagonistic effect on each other, the com- 
bination of Mg and Na chlorids proved more poisonous than either 
alone. 
SERIES VII. MAGNESIUM CHLORID vs. CALCIUM CHLORID 
The arrangement of the experiment and the ammonia determina- 
tions were. carried out in a manner similar to that employed in the 
two preceding series, two bivalent salts being tested this time. The 
results were as shown in table VII, p. 117. 
By an examination of the curve drawn on the basis of table vil 
(fig. 4) we are confronted by the very striking instance of lack of 
antagonism between the two salts. On the contrary, there is 2 Co” 
stant increase of the toxic properties of each when the other is added 
‘to it in increasing amounts. In this exceptional behavior, so far a5 
the writer can ascertain, B. subtilis (and probably all the ammonifiers) 
stand alone, when their physiological efficiency in such salt mixtures 
is compared with that of the higher plants and animals. No instance 
of such behavior on the part of any member of the latter two groups 
of organisms has come to my notice in reviewing the results of similar 
researches. 
An antagonism between CaCl, and MgCl,, though slight, Miler 
oP a ee 
