Relations of Manganese and Other Cations 



189 



water. Nevertheless, the manganese ion is poisonous in cultures that 

 contain all the essential nutrients. A number of cultures were made up 

 in order to determine whether further antidotal relations exist between 

 calcium and manganese when a full nutrient solution is employed as the 

 solvent. 



In general, the experiments demonstrate that calcium decreases the 



Fig. 12. 



Antidotal relations between calcium and manganese. Plants grown in full nutrient 

 solution for ten days, then transferred to 



1. N/10 CaCl2+N/50 A-InCU 



2. N/lOCaClo+N/lOO MnCl2 



3. N/10 CaCl2+N/200 MnCb 



4. N/100 MnCl2 



5. N/10 CaCl2 



6. Distilled water 



deleterious action of manganese in the nutrient solution indicated, as 

 might be anticipated from the concentration of the bases. N/50 MnCl2 

 prevents growth of tops almost entirely. In this culture the lateral roots 

 are shorter and less numerous, but the main roots are longer, than those 

 on the control plants. 



The addition of sufficient CaCl2 to make the solution N/10, N/50, 

 N/100, or N/500 of the solvent, results in no reduction of the toxicity of 

 the above solution of manganese. 



