274 POISONOUS ACTION OF AMMONIUM SALTS UPON PLANTS. 



From all the observations described it follozvs that ammon- 

 7iiin salts have a noxious action upon phcsnogavious plants if there 

 is not a sufficient quantity of sugar present in the plant. The 

 sugar may convert the noxious ammonia into the indifferent as- 

 paragine, and therefore the noxious action is not noticed in well 

 nourished plants. 



