REFERENCES 49 



potassium, magnesium, iron, and calcium, serve largely as 

 aids in the manufacture and transport of food material. 

 Thev are no less necessary than the others but act more in 

 the nature of catalytic agents, not appearing in the final 

 product. They form a proper medium for enzyme action. 

 As a rule, in seed crops like the grains, phosphorus and 

 nitrogen appear more largely in the seeds than in the stems 

 and leaves where calcium and potassium predominate. 

 Sulphur, iron, and magnesium are more evenly distributed. 



REFERENCES 

 See References at end of Chapter I. 



