60 BIOLOGICAL PROBLEMS 



bowel, and passes into the blood, to be carried all 

 over the body. It does not have to undergo digestion, 

 like most foods, and this has been supposed to give it 

 special value as a rapid method of giving food. As 

 a matter of fact, it does not seem to be assimilated any 

 more rapidly than the simple sugars. 



When alcohol reaches the blood and tissues, these 

 very soon begin to oxidize it or burn it, and it dis- 

 appears practically completely. No more escapes 

 from the body unchanged than of a corresponding 

 amount of sugar, and the decomposition products are 

 the same whether alcohol or sugar is burned. Now 

 we know that alcohol in the form of a spirit-lamp can 

 be used as a source of heat outside the body, and 

 the same is true in the tissues; alcohol, therefore, 

 serves as a sort of internal spirit-lamp to keep up the 

 body temperature. But a spirit-lamp is also capable 

 of doing work, as is shown in many toys in which an 

 engine is driven by a sponge soaked in alcohol; and 

 it must have been a grief to some to see alcohol used 

 even to drive motor-cars in late years. The com- 

 bustion of alcohol outside the body can therefore be 

 utilized for work as well as for heat. Can the body 

 utilize alcohol to do work in the same way? The 

 answer is beyond question. The most careful exami- 

 nation by measurement of the amount of work done 

 has shown that the human muscles can utilize alcohol 

 as a source of power just as they can utilize sugar 

 and just as the engine can draw its power from burn- 

 ing alcohol. And the change is the same in each 

 case: the alcohol is burned in the body just as in the 

 engine, and with the same completeness. The only 

 difference is that the alcohol is destroyed in the body 

 at a much lower temperature, owing to the activity of 

 certain special conditions and powers which we call 

 enzymes. Alcohol is thus a source of energy to the 



