266 KUNKEL: FACTORS INFLUENCING TOXICITY OF 
are formed. Of still greater significance, however, is the bearing 
of such studies on the actual det ination of the relative toxicity 
of different substances and the fundamental questions as to the 
nature of toxic effects in general. 
In a former paper (15) I have already shown that the toxic 
action of various nitrates on Monilia sitophila (Mont.) Sacc. is 
greatly influenced by the medium in which the fungus is grown at 
the time it is being poisoned. For example, ferric nitrate and 
aluminum nitrate were found to be much less toxic in peptone 
media than in glucose, fructose, galactose or starch media. 
Barium nitrate, on the other hand, was more toxic in peptone 
media than in glucose, fructose or starch. Through further 
experiments which it is the purpose of this paper to report, I have 
studied the influence of carbohydrates and peptone on the toxicity 
of eleven different chlorides. Observations on the germination 
and growth of Monilia in slightly toxic media has led to the 
suggestion that an important effect of a toxic substance may be 
to diminish the rate of water absorption by the fungus. In the 
hope that this suggestion might throw light on the conditions 
that obtain in poisoned cultures, I have also studied the influence 
of the water supply on the rate and amount of growth which 
Monilia makes when growing in various media. 
As already noted the discovery of the mutual antagonism which 
exists between inorganic salts as regards their toxicity to plants 
has led to the conception of balanced solutions. Boehm (3) was 
perhaps the first to observe this relation. He found that the 
poisonous action of magnesium salts on bean plants could be 
counteracted by calcium carbonate. He also noted that calcium 
nitrate and calcium sulphate had an ameliorating influence on 
the toxicity of sodium and potassium salts. Von Raumer (26) 
also observed the great toxicity of magnesium salts in the absence 
of calcium. The literature on this subject has recently been 
summarized by McCool (21) That such mutual antagonism 
exists between a rather large number of salts is one of the best 
established facts of plant physiology. 
In 1902 Loeb (18) attacked the further problem as to whether 
or not the presence of non-electrolytes would effect the toxicity of 
inorganic salts. Using the eggs of Fundulus, he measured the 
