CHAPTER III 

 ASSIMILATION 



Steps in the Process. — Living matter has the power to 

 take in substances called foods and out of them to manu- 

 facture new living matter. The process by which food^> 

 are converted into the body substance is called assimila- 

 tion. 



Broadly the word includes all the steps in the process. 

 We must therefore consider (1) The nature of food. (2) 

 The way it is taken into the body. (3) The way it is 

 made fit for the use of the body. (4) Its transportation 

 to all parts of the body. (5) Its conversion into proto- 

 plasm and other unstable substances. (6) The elimina- 

 tion of waste materials. In this broad sense respiration, 

 which provides much of the oxygen that is used in the 

 manufacture of protoplasm a nd_in the oxidation j )f, 

 wastes, and circulation, which carries substances from 



place to place in the body, are phases of assimilation. 

 In this chapter we shall confine our attention to the 

 assimilation of the food that we eat. 



Nature of the Process. — It is clear that young animals 

 must assimilate food, for they could not grow were it not 

 for the addition of new material. But why should an 

 animal continue to form new protoplasm after it has 

 reached its full size ? 



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