184 



M. M. McCooL 



TABLE 5. Experiment with Peas, Continued for Fifteen Days. Data for Ten 



Plants 



Culture* 



Composition of 



solution 



(nutrient 



solution as 



the solvent) 



Green 

 weight 



of 



roots 



(grams) 



Total 

 green 

 weight 



(grams) 



Average 

 length 



of 

 tops 

 (centi- 

 meters) 



Remarks 



1 



N/25MnCl. 



N/25MnCl2 



N/50MnCl2 



N/50MnC1.2 



N/100 MnCl2 



N/100 MnCh 



Nutrient solution . . 

 Nutrient solution . . 



2.0 



2.0 

 2.2 



2.5 



2.4 



2.6 



2.6 

 2.5 



2.6 



4.3 

 3.7 



6.6 



4.9 



8.2 



' 9.7 

 9.7 



2 



10 

 5 



18 



7 



22 



15 



27 



Leaves chlorotic from 



2 



3 



first. Dead at close of 



experiment 

 Leaves little injured, dark- 

 ened in places 

 Leaves yellow from first. 



Few alive at close of 



experiment 

 Leaves uninjured, stems 



slightly darkened in 



places 

 Leaves chlorotic after 



4 



5 



6 



three days. About one 

 half of the leaves dead 

 Leaves and stems un- 



7 



injured 

 Ijcaves dark green 



8 



Leaves uninjured 







* The odd numbers represent plants grown in light, the even numbers those grown in darkness. 



.-m 



07 



Fig. 10. — Influence of light on toxicity of manganese 



N/2.5 MnCl2+ nutrient solution in light 

 N/25 MnCk+nutrient solution in darkness 

 N/50 IMnCli+nutrient solution in light 

 N/50 MnCh+nutrient solution in darkness 



5. N/100 MnCl2 +nutrient solution in light 



0. N/100 :\InCl2-|-nutrient solution in darkness 



7. Nutrient solution in light 



8. Nutrient solution in darkness 



