TOXICITY OF VARIOUS NITRATES TO MONILIA SITOPHILA 637 
and ferric nitrate, on the other hand, are far less toxic in peptone 
than in the other substances used. Urea nitrate is more toxic in 
starch media than in peptone media, while the toxicity of ammo- 
nium tartrate is the same in the two media. 
DISCUSSION 
My observations show beyond question that the concentration 
at which various inorganic salts are toxic to Monilia sitophila 
depends on the kind of organic substances contained in the media 
to which those salts are added. The same substance at a given 
concentration may be highly toxic in one medium but quite 
harmless in another. The concentration of ferric nitrate that 
inhibits the growth of Monilia in starch media has little or no 
effect upon its growth in peptone media. Lipman (3), using a 
peptone medium, found that calcium chloride is more toxic to 
Bacillus subtilis than is potassium chloride, sodium chloride, or 
magnesium chloride. My experiments suggest that he might 
have obtained a different result by adding these chlorides to a 
medium containing starch or sugar instead of peptone. Ssadikow 
(5) has tested the toxicity of strychnin salts to Bacillus subtilis, 
using as his media, bouillon, nutrient agar, and nutrient gelatin. 
He found this organism able to withstand a surprisingly high 
concentration of these salts. A very different result might have 
been obtained if the strychnin salts had been added to media 
lacking in peptone. 
We have in such experiments, it seems to me, a means of 
attacking the whole question as to the nature of toxicity and toxic 
effects from an important and rather neglected standpoint and I 
hope to extend this work to a study of still other combinations of 
toxic and non-toxic substances as regards their effects on various 
living organisms. It is also obvious that such data are necessary 
toa proper understanding of the effects of various food substances, 
drugs, etc., both from the standpoint of the significance of the 
medium with which the chemical is combined when offered as a 
food and from the standpoint of its relation to the organic reserve 
and other substances which it meets in the cell. 
