Topics: Proper application of the results of scientific research helpful to mankind. Dietary habits should be brought into conformity with the true needs of the body. The peculiar position of proteid foods emphasized. The evil effects of overeating. What the new dietary standards really involve. The actual amounts of foodstuffs required. Relation of nutritive value to cost of foods. The advantages of simplicity in diet A sample dietary for a man of 70 kilograms body-weight. A new method of indicating food values. Moderation in the daily dietary leads toward vegetable foods. The experiments of Dr. Neumann. The value of fruits as food. The merits of animal and vegetable proteids considered in relation to the bacterial processes in the intestine. A notable case of simplicity in diet. Intelligent modification of diet to the temporary needs of the body. Diet in summer and winter contrasted. Value of greater protection to the kidneys. Conclusion.

KNOWLEDGE has value in proportion to the benefit it confers, directly or indirectly, on the human race. Every new scientific fact or principle brought to light promises help in the understanding of Nature's laws, and when rightly interpreted and properly applied is sure to aid in the advancement and prosperity of the individual and of the community. Proper methods of living, economical adjust* ment of the intake to the varying needs of the body, avoidance of excessive waste of foodstuffs and of energy, are all desirable precepts, which rational people presumably are inclined to follow so far as their knowledge and understanding of the subject will permit. Here, as elsewhere, false teaching may be exceedingly mischievous and lead to costly errors; while blind reliance upon customs, instinct, and superstitions is hardly in keeping with twentieth-century progress.

Modern scientific methods should give us help in dietetics, as in other branches of hygiene and practical medicine. A few short years ago, diphtheria was a scourge which brought misery to many a home, for there was at hand no adequate means of combating the disease; but scientific research has given us new light, and placed at our command a weapon of inestimable value. Do we hesitate to use it when the occasion arises, because it happens to be out of keeping with old-time customs and traditions? No, we recognize the possibility of help, and as the need is urgent we turn to it quickly, with hope and thankfulness that scientific progress has opened up a pathway of escape from a threatened calamity.

Not many years ago we drank freely of such water as was at hand, without realization of danger from bacteria or disease germs, looking on epidemics of typhoid fever perhaps as a visitation of Divine Providence, in punishment of our many sins and to be borne meekly and with resignation. But all this has changed through the researches of bacteriologists and chemists; scientific facts of the utmost importance have been clearly established; a classification of water-borne diseases has been adopted, and we realize fully that diseases of this order can be kept from our doors by proper precautions applied to our water supply. To-day, epidemics of typhoid fever are traceable solely to the ignorance or carelessness of the individual or of the commonwealth, and the exemption which we of the present generation have from this class of diseases is directly due to the application of precautionary measures based on the information furnished by scientific investigation. It is proper for us to use caution in the acceptance of new ideas, but not that form of caution which refuses change on the ground that what has been is sufficiently good for the present and the future. The point of view is ever changing with advance of knowledge, and it is not profitable to exclude opportunities for improvement in personal hygiene and general good health, any more than in other matters that affect the prosperity of the individual or the community.

Dietary habits should be brought into conformity with the true needs of the body. Excessive consumption of proteid food, especially, should be avoided on the ground that it is not only unnecessary and wasteful, but is liable to bring penalties of its own, most undesirable and wholly uncalled for. We may, perhaps, accept these statements at their full value, and yet have a shadow of doubt in our minds as to whether, after all, dietary customs do not harmonize sufficiently at least with true nutritive requirements. All the data that we have presented in the preceding chapters, however, have seemingly given a positive answer to such doubts, and indicate quite clearly that the results of scientific study are opposed to the prevailing dietary standards, especially as regards proteid food. As the celebrated physiologist Bunge has expressed it, "The necessity for a daily consumption of 100 grams of proteid is incomprehensible, so long as we do not know of any function of the body in the performance of which the chemical potential energies of the destroyed proteid are used up."

Perfectly trustworthy evidence is at hand showing that the needs of the body for potential energy can be fully met, and indeed are more advantageously met, by the non-nitrogenous foods, carbohydrates and fats. The energy of muscle work, as we have seen, comes preferably from the breaking down of non-nitrogenous material, so that there is no special call for proteid in connection with increased muscular activity. In fact, it would appear that the need for proteid food by man is limited to the requirements of growth and development reinforced by the amount called for in that form of tissue exchange which we have emphasized under the term "endogenous proteid metabolism." or true tissue metabolism. To be sure, there must be a certain reserve of proteid, available in case of emergency, but this is easily established without resorting to excessive feeding.

The peculiar position which proteid foods occupy in man's dietary naturally make them the central figure, around which the other foods are grouped. No other form of food can take the place of proteid; a certain amount is needed each day to make good the loss of tissue material broken down in endogenous katabolism, and consequently our choice and combination of the varied articles of diet made use of should be regulated by the amount of proteid they contain. But while proteid foods occupy this commanding position, it is not necessary or desirable that they should exceed the other foodstuffs in amount, or indeed approach them in quantity. We must be ever mindful of the fact, so many times expressed, that proteid docs not undergo complete oxidation in the body to simple gaseous products like the non-nitrogenous foods, but that there is left behind a residue of non-combustible matter - solid oxidation products - which are not so easily disposed of. In the forceful language of another, " The coni-bustion of proteid within the organism yields a solid ash which must be raked down by the liver and thrown out by the kidneys. Now when this task gets to be over-laborious, the laborers are likely to go on strike. The grate, then, is not properly raked; clinkers form, and slowly the smothered fire glows dull and dies " (Curtis).