146 FOODS 



would continue to live very well on a diet thus describable. By force of 

 poverty or other adverse conditions millions even of men and women 

 subsist their lives through on a very few of the staple articles of food, such 

 as rice and other starchy nutrients. We are trying to become familiar, 

 however, with an ideal diet physiologically adapted to such men, women, 

 and children as most of us are concerned with in civilized (perhaps 

 overcivilized) modern lands. To men who are more than the victims of 

 an unkind nativity and more than animals, variety in their food is 

 important, indeed practically essential. We might even go farther and 

 maintain that the basal requirements of composition being always 

 satisfied, the greater the variety in the food the better is the organism 

 served by it. In obtaining an understanding of the facts and principles 

 of digestion, in the next chaper we shall see that the conditions under 

 which the softening and hydrolyzing secretions of the alimentary canal 

 are augmented or, on the other hand, inhibited are very intricate. This 

 might be expected in an organism as uniquely complex as that of man, com- 

 bining in its functions mind as well as body. Even if the tissue-cells 

 are supplied with what they demand of food quantitatively as well as 

 qualitatively, the mechanism which immediately furnishes to them this 

 nutriment is discriminative. Because, perhaps, of its close connection 

 with the sensitive brain it soon demands a change in the quality of its 

 supplies when forced to work on a small series of foods. We tire of 

 almost all sorts of food eaten to excess, and the more quickly the greater 

 the sameness and the stronger the flavors. The organism's require- 

 ments are in this respect, out of many, self -regulating, and on the one side 

 demand that the foods shall be not too much alike in taste (and to a less 

 extent in odor), and, on the other hand, that they shall be not too strongly 

 flavored. So, as a practical outcome of this natural tendency, we see that 

 wheat-bread and the staple sorts of meat, eggs, milk, plain soups, and 

 vegetables, feebly flavored, constitute the great bulk of our usual diet. 

 Sugar is an important nutrient which is almost an exception to this rule, 

 for exceedingly few or no individuals of the animal kingdom, from insects 

 to man, young or old, seem ever to weary of its sweetness. Indeed, this is 

 a word in all languages adopted metaphorically for delight and pleasant- 

 ness. It is of small account if any new article of food has an unpleasant 

 flavor, for when familiar, such a flavor becomes pleasant. As no two 

 articles of food taste quite alike, the natural way to obtain this variety 

 of flavor with its consequent and more important variety of composition, 

 is to use as nutrients many sorts of substances, mineral, vegetable, and 

 animal, from many various places, earth and air and sea. The organism 

 naturally is after a wide variety of elementary and compound materials 

 which in their union in the gut shall always form an average pabulum 

 ample and nearly invariable in its absorbable products. By this wide- 

 gathering of many substances whose limits of strangeness are guarded 

 by taste and smell and the sense of nausea, the organism best secures its 

 ends in this respect. We have seen already the chemical basis of this 

 unity-in-variety, and it needs no further elaboration. 



