118 Contents 



PAGE 



II. The toxicity of manganese and the antidotal relations between 

 this and various other cations with respect to green 



plants 171 



Occurrence of manganese in soils 171 



Occurrence of manganese in plants 172 



The role of manganese 172 



Experimental studies 178 



Toxicity of manganese 178 



Influence of light on the injurious action of manganese 



with respect to plants 182 



Antidotal relations of calcimn, potassium, sodium, and 



magnesium toward manganese 185 



Calcium and manganese 185 



Potassium and manganese 193 



Sodium and manganese 196 



Magnesium and manganese 196 



Conclusions 198 



Bibliography 198 



III. Toxicity of various cations 201 



Historical 201 



Experimental 201 



Toxicity of calcium 202 



Toxicity of potassium 203 



Toxicity of sodium 203 



Toxicity of magnesium 205 



Toxicity of ammonium 206 



Toxicity of barium 207 



Toxicity of strontium 207 



Influence of previous conditions of growth on the resistance 



to the toxicity of various ions 208 



Influence of certain salts on germination of Canada field 



pea seed 210 



Conclusions 214 



Bibliography 215 



Acknowledgment 216 



