THE INFLUENCE OF CALCIUM, MAGNESIUM AND 



POTASSIUM NITRATES UPON THE TOXICITY 



OF CERTAIN HEAVY METALS TOWARD 



FUNGUS SPORES. 1 



LON A. HAWKINS. 



ABSTRACT. 2 



This study has to do with the influence of one salt in altering the toxic 

 effect of another upon fungus spores. It is shown that the toxic effect 

 of copper nitrate on the germination of Gloeosporium spores can be in- 

 hibited or modified by the addition to the medium of calcium nitrate and 

 that the molecular ratio of the quantity of the calcium salt thus required 

 to the amount of copper nitrate present increases with the concentration 

 of the latter. This effect is apparently the result of a simultaneous action 

 of the two salts upon the organism and cannot, in the cases here con- 

 sidered, be related either to formation of an undissociated double salt or 

 to depression of the ionization of the toxic salt because of the ion common 

 to the two salts. Potassium nitrate is also effective in inhibiting or 

 modifying the toxicity of copper nitrate. The influence of calcium upon 

 the toxicity of copper is of interest in connection with the problem of 

 fungicides and fungicidal action. 



The toxicity of lead nitrate is similarly influenced by the presence of 

 calcium nitrate, and the molecular proportions in which these two salts 

 may be combined so as just to counteract the toxicity of the former were 

 found to be the same for the three different concentrations of lead 

 nitrate that were employed. The toxicity of this lead salt is likewise influ- 

 enced by proper concentrations of magnesium nitrate. Both calcium nitrate 

 and magnesium nitrate markedly decrease the toxicity of zinc nitrate, but 

 neither exhibits any effect on the toxicity of aluminum nitrate in the con- 

 centrations used in these experiments. 



The effects produced by the various single salts upon the germinating 

 spores are of interest. Four types of response to the salt solution are 

 clearly discernible, (i) The effect of the solution may be the same as 

 that of distilled water, the spores germinating normally, with long, narrow 

 tubes. (2) A somewhat higher concentration of the toxic substance may 



'Botanical contribution from the Johns Hopkins University No. 31. 



2 The manuscript of this paper was received April i, 1913. This abstract was preprinted, without 

 change, from these types and was issued as Physiological Researches Preliminary Abstracts vol. i, no. 

 2, August, 1913. 



57 



PHYSIOLOGIC/ L RESEARCHES VOL. I, NO. 2^ SERIAL NO. 2, 

 AUGUST, 



"814805 



