WHAT FEEDING STUFFS CONTAIN 



necessary, because not only more life substance is 

 required as the plant grows larger, but because in 

 one kind of work that the plant does some of the 

 life substance is used up. Not all of the starch, 

 therefore, remains as originally formed; some of it 

 is assimilated along with other foods taken up by 

 the roots, and living material is made. 



Protein. The 

 formation of the 

 protein constit- 

 uents is more com- 

 plexthan the 

 formation of 

 starch. In a gen- 

 eral way it may be 

 said that starch or 

 some starch deriva- 

 tive is united in the 

 cells with nitrates 

 and sulphur that 



have been brought STARCH CELLS 



into the plant from 

 the soil. The liv- 

 ing matter, or protoplasm, then breaks up the 

 nitrates in the active cells, uniting them in some 

 way with starch, with the result that a protein com- 

 pound is formed. 



Fat or Oil. Oil is made out of the same chemical 

 elements that enter into the building of starch 

 grains. Both are formed of carbon, hydrogen and 

 oxygen. In the oil compounds there is a larger 



This is the way the starch cells from potato 

 tubers look when seen under the microscope. 



