Fig. 7. Photograph showing the action of anhydrous zinc sulphate on pea plants in 

 the presence of nutrient salts. (Sept. 30th Dec. 20th, 1912.) 



1. Control. 



2. 1/5,000 



3. 1/10,000 



4. 1/50,000 



5. 1/100,000 



6. 1/250,000 



7. 1/500,000 



8. 1/1,000,000 



9. 1/2,500,000 



zinc sulphate. 



