OXIDATION 



35 



twice as much heat as the same amount of albumin, and 

 is thus a good food for cold weather. It leaves no ashes 

 behind, for it contains no mineral matter. 



41. Oxidation of sugar. An ounce of sugar is com- 

 pletely oxidized by one and one fifth ounces of oxygen. 

 So it produces only about half as much heat as fat. It 

 is much more easily oxidized than fat or albumin. When 

 the three substances are mixed together as they are in the 

 body, the oxygen will go to the sugar in preference to 

 the fat or albumin, and the latter two substances being 

 unburned will accumulate in the body. Thus sugar is 

 said to be fattening. The water and the minerals of the 

 body cannot be oxidized, but enter 



and leave the body unchanged. 



42. Reconstruction of living mate- 

 rial by plants. In every animal the 

 living cells are continually uniting 

 with the oxygen of the air and giving 

 out carbonic acid gas, water, and min- 

 eral matters. From these waste mat- 

 ters plants reconstruct the substances 

 which were oxidized in the body. 

 The first substance produced seems 

 to be starch, and from it as a basis all 

 other parts of the plant and of ani- 

 mals are built up. 



The plant cells which contain 

 green coloring matter called chloro- ^ 



phyll, are set apart for the special a Chlorophyll arranged in 

 work of reconstructing starch from a spiral. 

 oxidized material. To them the sap * The ^ arb ^yoftheceU. 

 brings water from the soil, and carbonic acid gas from 

 the air. In the chlorophyll these substances are recon- 



