92 Effect of Manganese Compounds 



Conclusion. 



Manganese exerts a toxic influence upon the higher plants, if it is 

 presented in high concentration, but, in the absence of great excess of 

 the manganese compounds, the poisoning effect is overshadowed by a 

 definite stimulation. As is the case with boron, manganese stimulates 

 some species more than others, the action on barley being more evident 

 than that on peas. It seems probable that manganese may prove to be 

 an element essential to the economy of plant life, even though the 

 quantity usually found ia plants is very small. 



