Fig. 19. Photograph showing the action of manganese sulphate on pea plants 

 in the presence of nutrient salts. (Oct. 2nd Dec. 20th, 1912.) 



Control. 



1/5,000 



1/10,000 



1/25,000 



1/50,000 



1/100,000 



1/250,000 



1/500,000 



1/1,000,000 



manganese sulphate. 



