THE ACTION OF CERTAIN NUTRIENT AND NON-NUTRIENT 

 BASES ON PLANT GROWTH — III 



TOXICITY OF VARIOUS CATIONS* 



M. M. McCooL 

 (Received for publication July 1, 1912) 



HISTORICAL 



As a result of numerous investigations that have been made on antag- 

 onistic action and toxic action, there are available for green plants many 

 data with respect to the relative toxicity of certain nutrient and non- 

 nutrient substances. In the first part of this paper extensive data have 

 been reviewed and presented regarding the modification of toxic action 

 in mixed solutions, especially the effects of the cations, one on another, 

 of the substances constituting the nutrient solution. Furthermore, the 

 experiments of Guthrie and Helms (1903-1905), Kanda (1904), Cameron 

 and Breazeale (1904), Dandeno (1904), Harter (1905), True and Oglevee 

 (1905), Jensen (1907), jMagowan (1908), Duggar (1911), and others have 

 shown that, as a rule, substances are far less toxic in the presence of inert 

 solid particles, sand, or soil, than when present in pure solutions. 



The reduction of toxicity by quartz sand, soil, and other solid particles 

 has been attributed to the following factors: chemical reactions between 

 the solute and the solid particles, resulting in the formation of less toxic 

 substances; adsorption of the molecules or ions of the toxic agent; and 

 obstruction to the free movement of the molecules or ions in solution. 



The reduction of the toxicity of deleterious agents when present in 

 nutrient solutions maj' be attributed in part to chemical reactions that 

 result in the formation of less toxic substance, to a decrease in penetra- 

 bility of the protoplasmic membrane, and perhaps to other important 

 factors. 



EXPERIMENTAL 



The writer has made comparative studies of the poisonous action of 

 the chlorids of calcium, potassium, sodium, magnesium, ammonium, 

 barium, strontium, and manganese, in distilled water, in full nutrient 



* Laboratorj' of Plant Physiolog:/, Cornell University, Contribution No. 11. 



201 



