Relations of Manganese and Other Cations 



187 



lings modifies the protective action of calcium toward manganese, seedlings 

 were permitted to grow for ten days in pure distilled water and were 

 then transferred to single and 

 mixed solutions of calcium and 

 manganese. Final notes were 

 taken twenty clays later. It 

 was thought that changes which 

 would alter the relations of 

 the calcium and manganese 

 might occur in the protoplasm 

 of the cells of the older seed- 

 lings. The results obtained 

 show clearly that, although the 

 lethal concentrations of man- 

 ganese are much higher for 

 older seedlings, calcium counter- 

 acts the toxicity of this element 

 in the same manner as before. Slight elongation of the tops takes place 

 when the plants are placed in N/200 MnCl2. A solution of N/100 causes 

 death within three days. The addition of N/10 CaCl2 to the above 

 solutions of manganese results in complete reduction of the toxicity. 



Fig. 11. — Antidotal relations between cileiutn and 

 manganese. Seedlings in distilled water for ten 

 days, then transferred to 



1 



N/10 CaCl2+N/100 MnCb 

 N/10 CaCl2 



Distilled water 

 N/100 MnCU 



TABLE 7. Experiment Continued for Twenty Days. Data for Ten Plants 



Previous condition of 

 growth 



Composition of 

 solution 



Total green 

 weight 

 (grams) 



Average 

 length 

 of tops 

 (centi- 

 meters) 



Average 

 length 

 of roots 

 (centi- 

 meters) 



Ten days in distilled water 



N/10 CaCl2 



N/10 CaC]2+N/100 



MnCl2 



N/10 CaCl2+N/200 



MnCl2 



N/100 MnCl2 



N/200 MnCl2 



Distilled water 



9.45 



8.65 



8.82 

 Dead after three 



days 

 Weight not taken 



2.50 



15 

 13 

 14 



SHght in- 

 crease 



No increase 

 6 



