Fig. 4. Photograph showing the action of copper sulphate on pea phints iu the 

 presence of nutrient salts. (Oct. 3ril — Dec. 'iOtli, 1912.) 



Control. 

 1/50,000 



i/ino,onn 



1/2.50,000 



]/.100,000 



1/1,000,000 



1/2,500,000 



1/5,000,000 



1/10,000,001) 



1/20,(100,000 



coppel' sulphate. 



