CHAPTER XI 



TISSUES FOR SYNTHESIS, ASSIMILATION AND 

 STORAGE 



The plant possesses the power of building up the 

 very simple chemical compounds absorbed through 

 the root hairs and stomata into nutrients of complex 

 composition. In other words, the plant must con- 

 struct its nutrients before assimilating them. This 

 procedure is quite different from the nutrition process 

 in animals, as the food materials of the latter consist 

 of complex nutrients which undergo analytic changes 

 in the organism. 



SYNTHESIS OF NUTRIENTS 



Synthetic processes occur in many organs of the 

 plant; but the most important are those occurring 

 in the leaves and green stems. Starch is the most 

 important plant nutrient; and, as chloroplasts are 

 responsible for its formation, the synthesis of this 

 substance occurs only in the green parts of the plant. 

 As the chemical changes occurring in the formation 

 of starch are initiated by, or are dependent upon, the 

 action of light rays, the process is termed a photo- 

 synthesis. The crude materials entering into the 

 formation of starch are water and carbon dioxide. 

 These simple substances are built up into the complex 

 starch molecule by the chloroplasts. There is much 



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