168 BOTANICAL GAZETTE [MARCH 
which, if present in too great a proportion in the cell, confer upon 
the protoplasm properties which are incompatible with the mainte- 
nance of normal functioning. The toxicity of calcium salts is like- 
wise attributed to an undue predominance of calcium proteinate 
in the cell. An admixture of several types of protein salts is 
required to give the protoplasm of the cell the exact qualities 
essential to the maximal furtherance of its vital activities. Two 
factors, therefore, may enter in the toxicity of a salt: (1) the 
permeability of the salt for the living protoplasm, and (2) the 
chemical, physical, or electrical influence of the salt upon the pro- 
toplasm after entering the cell. 
Those cases in which the osmotic influence is the predominating 
factor should show a marked decrease in toxicity when the solution 
is diluted (11); whereas in those cases in which the physiological 
effect predominates, the addition of another salt which would in- 
crease osmotic pressure may show a decrease in toxicity, due to a 
physiological balancing of the solution. 
Numerous experiments have shown that the relative toxicity 
of sodium chloride, sodium carbonate, potassium carbonate, and 
calcium carbonate, as measured in terms of ammonification, 
decreases as the water added to a soil increases. All the other 
salts become relatively more toxic, thus indicating that some 
factor in addition to osmotic pressure is entering. In this regard 
the nitrifying organisms act quite differently, and toxicity is 
neutralized with potassium chloride, potassium sulphate, magne- 
sium nitrate, and magnesium chloride, but not with the remaining 
salts when water is added. Were osmotic pressure alone the 
disturbing factor, it would be impossible to neutralize the toxic 
action of one salt by the addition of another, thus increasing 
osmotic pressure and at the same time decreasing toxicity. 
This conception of- antagonism and balanced solutions was 
first applied to a study of bacteria by Lipman in 1909. In his 
experiments (20) on the rate of ammonification of Bacillus subtilis, 
he showed that there is some antagonism between sodium an 
magnesium. On the other hand, he (21) found no antagonism, 
but increasing toxicity, when magnesium and calcium were com- 
