516 NUTRITION. 



absorbed as cane sugar or at most only inverted. Moreover, if our labora- 

 tory experiments truly represent the digestion taking place in the living 

 body, only part of the starch ( 194) is changed into maltose, while part 

 becomes some variety of dextrine or of starch. Our knowledge of sugars 

 and of their fate in the economy is too imperfect for us to be able to state 

 the effects on the body of digested starch as compared with those of cane 

 sugar or milk sugar ; but that these are or may be different is shown by the 

 experience of medical practice. In many cases the total effect on the body 

 of a diet from which cane sugar is as much as possible eliminated, though 

 starch be allowed, is very different from that of one of which cane sugar 

 forms an appreciable part. 



Concerning cellulose, which in herbivora appears certainly to serve as 

 a source of energy and to be a real food-stuff, our knowledge will not allow 

 us to decide whether it has any special uses of its own, or whether the body 

 is simply led to utilize and make the best of what is a necessary accompani- 

 ment of the starch of vegetable food. 



Concerning the salts present in a diet, we need only repeat what was said 

 in 440, that these, though affording of themselves little or no energy, are 

 as essential a part of a diet as the energy-giving food-stuffs, inasmuch 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 extra-vascular juices or lymph of the 

 tissues is essential to or directs or modifies the metabolic activity of the sev- 

 eral tissues. The beneficial effects, as components of special diets, of such 

 things as beef-tea and meat extract, which consist chiefly of salts and ex- 

 tractives, 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 show that the greater part of a moderate dose of alcohol is 

 oxidized within the body, and so serves as a source of energy, man ha& 

 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 can- 

 not 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 metabolism of the body, 

 while larger but still not intoxicating doses have a contrary effect and in- 

 crease 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 conclu- 

 sion, for example, as that alcoholic drinks, taken in moderation, by diminish- 

 ing metabolism economize the resources of the body. The prominent physio- 

 logical problem of dietetics is not either to increase or diminish the metab- 

 olism 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 partic- 

 ular 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,, 



