NUTKITIVE INGREDIENTS AND VALUES OF THE FOOD WE EAT. 677 



rather than in the liquid excrement. On leaving the 

 ash-ingredients wholly out of the account, it appeared 

 that the dry organic matter of milk was assimilated 

 almost as well as that of flesh and eggs ; though the 

 percentage waste of nitrogen from milk is noticeably 

 large perhaps because of the large amount of this 

 element which is taken into the digestive- tract when 

 nothing but milk is eaten. There is, of course, a 

 limit to the digestibility of every food, milk included. 

 Speaking in general terms, however, it is simply the 

 ash-ingredients in milk tliat are not needed by adult s 

 which are discarded. In harmony with this fact, it 

 has been noticed that milk is assimilated more com- 

 pletely by children than by adults. 



The completeness of the assimilation of the " car- 

 bohydrates" that is to say, starch, from foods rich in 

 this constituent is specially remarkable. It appears 

 that men are able to digest and absorb very large 

 quantities of starch when it is presented to them in 

 suitable forms, as in rice, white bread, and macaroni ; 

 unless, indeed, a great deal of fat is eaten at the same 

 time with the starch, in which event some of the latter 

 is apt to escape digestion. In the case of potatoes, 

 black bread, beets, and cabbage, on the other hand, 

 the carbohydrates arc utilized much less completely ; 

 doubtless because they are of less digestible kinds in 

 the vegetables, and also because each of the foods last 

 mentioned produces large quantities of bulky, watery 

 excrement which passes rapidly through the intes- 

 tines, and carries with it much carbohydrate and other 

 material, which would doubtless have been assimi- 

 lated but for lack of time. Not only are the intestines 

 overburdened by these coarse foods, but the partially 

 digested material is subject to fermentations which 

 produce butyric and lactic acids, and a quantity of 

 gases, all of which appear to hasten the evacuation of 

 the intestines, and consequently occasion less complete 

 assimilation of the constituents of the food than would 

 otherwise occur. Any solid, non- digestible substance 

 added to food, such as bran, for example, or cellulose 

 prepared from straw, makes the assimilation of the 

 digestible constituents of the food less complete than 

 it would be if the indigestible substance were absent. 

 Of a given amount of starch, that would be completely 

 assimilated if eaten in the shape of rice, white oreaa, 

 or macaroni, no inconsiderable portion goes to waste 

 if it be eaten in the form of black bread. In experi- 

 ments where the diet consisted of beets alone, wliich 

 were eaten, of course, in large quantities, the intestines 

 were so overloaded that excrement began to be dis- 

 charged five or six hours after the first meal was 

 eaten. 



Rice is assimilated pretty well, particularly as re- 

 gards its starch (carbohydrates). Indeed, in so far as 

 dry substance goes, rice is assimilated as completely 

 as flesh ; it is the nitrogenous constituents chiefly 

 which fail to be absorbed. So too with Indian corn ; 

 a good deal of its nitrogen is not assimilated, while its 

 carbohydrates are pretty thoroughly absorbed. With 

 potatoes, also, a very considerable part of the ni- 

 trogenous constituents are not assimilated, and the 

 amount of excrement is large. Particularly large 

 amounts of excrement were produced when the food 

 consisted of beets or of cabbage. As the table shows, 

 very considerable portions of these foods were not as- 

 similated. As a general rule, fat is assimilated well- 

 nigh completely, even when eaten in large quantities, 

 though exceptions to this rule occur ? and arc not al- 

 ways easy to explain. The fat of Indian corn, for ex- 

 ample, and that eaten with cabbage, appear to be less 

 easily assimilated than some others. Butter is assimi- 

 lated better than fat bacon, and the appearance of par- 

 ticles of unchanged bacon in the excrement would 

 seem to show that the cellular envelopes of such fat 



hinder its digestion; but fat from the marrow of 

 bones, in spite of its cellular condition, is assimilated 

 almost as completely as that in butter, though this 

 fact may perhaps depend on the easier fluidity of the 

 marrow fat, and it is possible withal that the cells 

 of the marrow may be less tough than those of tie 

 bacon. 



In Conclusion. Cheap versus Dear Foods. 

 The figures in the last column of the tables 

 include the following nutritive valuations of 

 animal foods : 



It appears, from comparison of the German 

 analyses of meats with those thus far made 

 of the corresponding American products, that 

 what is given above as "medium beef " would 

 be regarded here as rather lean. Since, how- 

 ever, the valuations are only relative, this is of 

 no great moment. 



These figures differ widely from the market 

 values. But we pay for our foods in propor- 

 tion, not simply to their value for nourishing 

 our bodies, but to their abundance and their 

 agreeableness to our palates. 



It makes very little difference to a man with 

 $5,000 a year whether he pays 25 cents or $5 

 a pound for the albuminoids of his food, but it 

 does make a difference to the housewife whose 

 family must live on $500 a year. And a little 

 definite knowledge of this sort will be of ma- 

 terial help to her in furnishing her table eco- 

 nomically. 



The cook-books and newspapers have occa- 

 sionally something to say upon these points, 

 but their statements are apt to be as vague and 

 far from the truth as, in the lack of authori- 

 tative information, they might be expected 

 to be. 



As already stated, the nutritive valuations 

 above given are only approximate, since they 

 are made with very imperfect knowledge of 

 either the digestibility of the foods or the in- 

 fluence of palatability and other factors upon 

 their nutritive value, and also because they are 

 based upon very few analyses. But it is certain 

 that we need to know more about these things, 

 and that proper investigations will help us to- 

 ward that knowledge. 



