INTRODUCTION 11 



there is no end to the making of words. The 

 simplest proteins consist wholly of amino acids. 

 These combine with inorganic salts, lime, phos- 

 phorus, iron, etc., and with carbohydrates to 

 form the compound proteins. 



All living things not only contain protein, 

 but this is their essential constituent. The 

 living protein molecule is in a labile or active 

 state, capable of trading in energy, absorbing 

 and eliminating ; never in a condition of equilib- 

 rium. Dead protein is in a state of rest; it is 

 a stabile molecule and remains in equilibrium. 



