MATTER AND ENERGY 67 



oxygen will be used up. But there is no 

 parallelism in the so-called oxidation in living 

 stuff. Oxygen may disappear in the process, 

 and the amount of combustion products cannot 

 always be accounted for by the amount of 

 oxygen used. Oxidation in living matter is 

 a complicated process. 



(2) Reduction is due to the abstraction of 

 oxygen. It plays an important part in the 

 chemistry of plant life, but it is not so common 

 in the animal body. Fats may be formed 

 from carbo-hydrates, as in the feeding of 

 pigs with starchy matter ; much more fat is 

 formed than can be accounted for by the fat 

 in the food. But fats presumably are formed 

 from carbo-hydrates (starches, sugars, etc.), 

 by the abstraction of oxygen. Not a few 

 substances passed through the body suffer 

 reduction. Thus the iodides and bromides 

 of the alkalies are formed from iodates and 

 bromates, and malic acid (as in fruits), becomes 

 succinic acid. 



(3) Decompositions frequently occur, when 

 complex substances are split into simpler 

 ones. Thus taurocholic acid, the acid of one 



