290 KUNKEL: FACTORS INFLUENCING TOXICITY OF 
flavus, Sterigmatocystis nigra, Oedocephalum albidum, Penicillium 
glaucum and Botrytis vulgaris, Clark (4) used a sugar beet infusion. 
Klebs (14) determined the poisonous influence of various sub- 
stances on Saprolegnia mixta growing ina peainfusion. Bessey (2) 
tested the resistance of fungi to copper sulphate, mercuric chloride 
and other poisons without taking into account the possible influ- 
ence of organic materials in the synthetic media which he used. 
Pulst (25) measured the toxicity of copper sulphate, zinc 
sulphate and nickel sulphate. He tested the action of these salts 
on Mucor Mucedo, Aspergillus niger, Botrytis cinerea and Pent- 
cillium glaucum in a medium containing sugar and peptone, with- 
out regard to the effect of sugar or peptone on the toxicity of the 
salts. 
Loew (20) has studied the poisonous action of sodium fluoride 
on Bacillus mycoides, B. pyocyaneus, B. subtilis and B. prodigiosus. 
Using a bouillon medium, he found that these bacteria could endure 
approximately one per cent. of sodium fluoride. He, therefore, 
disagrees with Arthus and Huber (1) who held that a one per cent. 
solution of this salt is deadly to all cells. He also compares the 
toxic action of sodium fluoride on Spirogyra communis in an 
aqueous solution with its effect on bacteria in a bouillon medium 
and notes that the bacteria have a much higher resistance than 
the alga. 
Ssadikow (29) studied the resistance of Bacillus subtilis to 
strychnin salts in bouillon, nutrient agar and nutrient gelatin. 
My observations suggest that the high concentrations which this 
organism was able to endure might have been fatal to it in a 
medium containing no peptone. Renard (27) has tested the anti- 
toxic action of different concentrations of each of twelve nutrient 
salts on the poisonous effects of eleven different toxic substances, 
mostly chlorides and nitrates of the heavy metals. He finds that 
in general, the antitoxic action increases with the concentration of 
the inhibiting salt. Except in a few cases where the antagonistic 
substance is a salt of an organic acid, he has made his tests in 
glucose media. The antitoxic coefficients by which he attempts 
to express the relations between the several poisons and their 
antidotes would undoubtedly have been found to be different for 
each medium tested if he had tried other common organic sub- 
