CHAP, v.] NUTRITION. 877 



what was said in 526 that these, though affording of themselves 

 little or no energy, are as essential a part of a diet as the energy- 

 giving food-stuffs, in as much as they in some way or other direct 

 metabolism and the distribution of energy. And this is true not 

 only of the inorganic salines such as chlorides and phosphates but 

 also of the so-called extractives. As we have seen, the presence 

 of these bodies, both the simpler inorganic and the more complex 

 organic salts, in the blood or in the extravascular juices or lymph 

 of the tissues is essential to or directs or modifies the metabolic 

 activity of the several tissues. The beneficial effects, as components 

 of special diets, of such things as beef-tea and meat-extract, which 

 consist chiefly of salts and extractives with a very small quantity 

 of albumose or other forms of proteid, and the effects either 

 beneficial or deleterious of drugs both turn in common upon their 

 taking a part of some kind or other in, it may be upon their 

 interference with metabolic processes. The salts and extractives 

 of a diet may be looked upon as necessary daily medicines, and a 

 medicine as a more or less extraordinary variation in these elements 

 of a diet. 



Alcohol, to the use of which as a component of an ordinary 

 diet special interest for various reasons attaches, comes in this 

 class. For though observations shew that the greater part of a 

 moderate dose of alcohol is oxidized within the body and so serves 

 as a source of energy, man has recourse to alcohol not for the 

 minute quantity of energy which is supplied by itself, but for 

 its powerful influence on the distribution of the energy furnished 

 by other things. That influence is a very complex one and cannot 

 be fully discussed here. It is stated that moderate or small doses 

 of alcohol diminish the consumption of oxygen and production of 

 carbonic acid, that is to say diminish the total result of the meta- 

 bolism of the body, while larger but still not intoxicating doses 

 have a contrary effect and increase the total metabolism. But 

 such a statement affords no sound basis for any conclusion as to 

 the general physiological effect of alcohol, or as to its usefulness 

 as part of an ordinary diet; it does not justify such a conclusion 

 for example as that alcoholic drinks, taken in moderation, by 

 diminishing metabolism economize the resources of the body. 

 The prominent physiological problem of dietetics is not either to 

 increase or diminish the metabolism of the body but to direct 

 that metabolism into proper channels; and whether in each 

 particular case a given dose of alcohol gives a right or a wrong 

 turn to the physiological processes of the body, depends on the 

 particular circumstances of the case. For the action of all these 

 bodies of which we are now speaking, in contrast with the actions 

 of the food-stuffs proper, is not only complex but variable; so 

 complex and variable that simple experience is at present a more 

 trustworthy guide* than speculative physiology. We may add that 

 the physiological action of alcoholic drinks is still further com- 



