THE SIGNIFICANCE OF THE FOOD-STUFFS 647 



by the lungs and urine. This oxidation of alcohol is a result of true utilisa- 

 tion, since the addition of a certain amount of alcohol to the food does not 

 result in an increase of the output of carbon dioxide. In small quantities 

 therefore alcohol can act as a food. This function, however, is quite un- 

 important, and is overshadowed by the poisonous action of this substance. 

 A man unaccustomed to its action cannot take more than 16 to 25 grm. 

 without experiencing its poisonous effects. This amount of alcohol only 

 represents a total heat- value of 112 to 175 calories, i.e. only about 5 per cent, 

 of the total energy requirements of the body. Only very rarely therefore 

 can we be justified in administering alcohol as a food. Its value in a diet 

 is entirely that of an accessory or adjuvant in exciting appetite by its taste 

 and smell, an advantage which is largely counterbalanced by the danger 

 of introducing a poison into the body which on long continuance tends to set 

 up various degenerative changes in the tissues, and if taken in any quantity 

 at one time causes a temporary abolition of those processes of inhibition and 

 control which have been the determining factors in the survival of the race 

 throughout the struggle for existence. 



THE INORGANIC FOOD-STUFFS 



If an animal be fed with the proper quantities of fats, proteins, and 

 carbohydrates, from which all the salts have been removed as completely 

 as possible, it rapidly shows a distaste for the food, becomes ill, and dies in 

 a shorter time than if it were receiving no food at all. Part of the symptoms 

 which occur in these cases are due to the production of acid substances, e.g. 

 sulphuric acid, in the course of metabolism of the proteins. It is possible 

 to obviate this acid intoxication by administering sodium carbonate with the 

 food. This admixture, however, only suffices to prolong the life of the 

 animal for a short time. It is evident therefore that the inorganic constitu- 

 ents of the food, although yielding no energy to the body, are as essential for 

 the maintenance of life as the energy- yielding food-stuffs, namely, proteins, 

 carbohydrates, and fats. In the course of this work we shall have occasion to 

 study the intimate dependence of the functions of various tissues, such as 

 skeletal and heart muscle, on the presence of salts in normal proportions in 

 the fluids with which they are bathed. Animals in a state of salt hunger show 

 by the disorders of digestion which occur that the presence of salts is equally 

 requisite for the due performance of the processes of secretion and absorption. 

 Towards the end of the experiment the animal vomits its food, which shows 

 no signs of digestion even when it has lain some hours in the stomach. 

 Forster has shown that in salt-hunger the body is continually giving off 

 inorganic constituents in the urine. The amount of these is smallest when 

 it is supplied richly with organic food-stuffs. It seems that the salts of the 

 body exist in a state of unstable combination with the- tissue constituents, 

 especially the proteins. If the amount of food supplied is insufficient, the 

 animal lives on its own tissues, thus setting free salts which appear in the 

 urine. The loss of salts to the body will therefore be in direct proportion to 

 the degree in which the animal is living at the expense of its own tissues. 



