702 



PHYSIOLOGY 



On account of the greater relative metabolism of smaller animals, 

 their resistance to starvation is less than that of larger animals. A 

 rat or a mouse will only stand total abstinence from food for two or 

 three days. The difference is determined by the fact that a smaller 

 animal has a relatively larger surface per unit body weight than is 

 the case with a larger animal. The greater part of the energy set 

 free during starvation is required for the maintenance of the body 

 temperature. A larger amount of energy per kilo is required in 

 those animals with a relatively larger body surface through which 

 heat loss may occur. That the difference in relative surface is the 

 determining factor for the differences in total metabolism per kilo 

 body weight is shown by the fact that, if we reckon out the amount 

 of surface presented by each of the animals in the above list, we find 

 that the output of energy per square metre of body surface is approxi- 

 mately identical in all cases. This is shown in the following Table, 

 in which the calorie output per square metre of surface has been 

 reckoned for a number of animals of different weight : 



Speaking roughly, we may say that a warm-blooded animal 

 during starvation requires the daily expenditure of 1000 calories per 

 square metre body surface in order to maintain its temperature and 

 carry out such motor processes as are essential to life. 



THE METABOLISM OF CARBOHYDRATE, FAT, AND 



PROTEIN DURING STARVATION 



Since during starvation no energy is supplied to the body from 

 without in the shape of food-stuffs, we can regard the whole expendi- 

 ture of the animal during its period of starvation as occurring at 

 the expense of its capital. The amount of carbohydrate which can 

 be stored up as glycogen or other forms is strictly limited. In many 

 experiments the glycogen metabolism has therefore been entirely 

 disregarded, and it has been estimated that the chemical capital 

 of the body consisted entirely of proteins and fats. The glycogen 

 metabolism, however, during the first day of a period of starvation 



