Effect of Boron Compounds 77 



Conclusion. 



Boric acid is less harmful to the growth of higher plants than are 

 the compounds of copper, zinc, and arsenic. Evidence exists that below 

 a certain limit of concentration boron exercises a favourable influence 

 upon plant growth, encouraging the formation of stronger roots and 

 shoots. This stimulation is more strongly marked with some species 

 than with others, peas responding more readily than barley to the action 

 of boric acid. Fungi are very indifferent to boron, whether it is present 

 in large or small quantities, and there is evidence to show that certain 

 of the green algae can also withstand large quantities of it. 



