SECTION II 

 THE METABOLISM DURING STARVATION 



IT will tend to simplify our task if we deal first with the results 

 of the experiments which have been made on the metabolic ex- 

 changes of animals during starvation, i.e. during a period when the 

 whole energy involved in the maintenance of the movements of 

 respiration and circulation, and in the maintenance of the body 

 temperature, &c., is derived from the animal's own tissues. It must 

 be remembered that the tissues of an animal comprise two distinct 

 classes. In the first class must be placed the living machinery of the 

 body, generally composed of proteins or their near allies. In the 

 second class are the fatty tissues of the body, which form no part 

 of the ordinary machinery, but function simply as a storehouse 

 of material which can be utilised for the production of energy. In 

 addition to the store of fat there is, in a well-fed animal, a certain 

 reserve of carbohydrate in the form of glycogen, deposited in the 

 liver and muscles of the body. This store of glycogen is drawn upon 

 to a large extent at the beginning of a period of starvation. The 

 total amount of glycogen present at any time is so small in com- 

 parison with the possible amount of fat that it cannot provide the 

 energy necessary for the prolonged period during which the main- 

 tenance of life is possible in a complete state of inanition, although 

 it plays an important part during the first one or two days of a period 

 of starvation. 



Contrary to general belief, the condition of an animal which 

 is completely deprived of food is not a painful one. For this 

 statement we have not only such evidence as can be derived from 

 inspection of animals placed in this condition, but also evidence 

 derived from men who have voluntarily or involuntarily been 

 deprived of food for considerable periods. Especially instructive in 

 this connection are the cases of the so-called professional ' fasting- 

 men,' two of whom, Succi and Cetti, have been subjected to com- 

 plete metabolic investigation during the period of their starvation. 

 During the first day or two there is a craving for food at meal-times. 

 This, however, passes off, and during the later portions of the experi- 

 ment even the desire for food may be entirely absent. As might 

 be expected, the restriction of food is followed by a diminution in 



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