CHAPTER VI 



CHEMICAL REACTIONS IN LIVING 

 MATTER 



NE of the chief characteristics of living matter 

 is found in the continuous range of chemical 

 reactions which take place between living cells 

 and their inorganic surroundings. Without cease 

 certain substances are taken up and disappear in 

 the endless round of chemical reactions in the 

 cell. Other substances which have been pro- 

 duced by the chemical reactions in living matter 

 pass out of the cell and reappear in inorganic 

 nature as waste products of the life process. 

 The whole complex of these chemical transforma- 

 tions is generally called Metabolism. Inorganic 

 matter contrasts strikingly with living substance. 

 However long a crystal or a piece of metal is kept 

 in observation, there is no change of the substance, 

 and the molecules remain the same and in the 

 same number. For living matter the continuous 

 change of substances is an indispensable condition 

 of existence. To stop the supply of food material 

 for a certain time is sufficient to cause a serious 

 lesion of the life process or even the death of the 

 cell. But the same happens when we hinder the 

 passing out of the products of chemical transforma- 

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