It must therefore be evident that the new discovery is of immense importance to practical men and women with work to do in the world. Everybody would like to be up to his or her best all the time. Most of us experience only brief spurts of our maximum efficiency. If it be true that one of the leading causes, if not the leading cause, of the sense of inefficiency that hangs over us like a pall, is due to the fact that we are consuming an excess of food - then the new diet plan supplies us with at least one effective means of tapping those "new levels" of energy that Professor James speaks of in his famous essay, "The Powers of Men."4

For the benefit of those who may be inclined to reject the new plan - for all its advantages - on the grounds that it will interfere with the pleasures of the table, it may be stated that the universal testimony of those who have adopted it is that they never realized what true enjoyment of food was before they tried it. On this point Profes-sor Chittenden says:

"Simplicity of diet does not diminish but rather increases the pleasure of eating, especially when daily restriction in diet - indulged in until a new habit is formed - has created a greater keenness of appetite, since under such conditions the palate takes on a new sensitiveness, and manifests a fuller appreciation of the variations of even a simple dietary. There is therefore no hardship, nor curtailment of the pleasure of eating in the restriction of the diet to the real needs of the body. Neither is there implied any cessation of that kindly hospitality that delights in the ' breaking of bread' with one's friends. With enlightened methods of living, on the other hand, will come a truer appreciation of the dignity of the body, and a lessened desire to manifest one's feelings of hospitality by a lavish intemperance that is as unphysiological as it is wasteful."5

4 Professor William James: "The Powers of Men," American Magazine, November, 1907.

To those who are timid about adopting it because their "doctors told them it was dangerous to cut down the food that makes muscle," it may be pointed out that no one - doctor or not - who has not made an exhaustive study of the subject with the same thoroughness or the same facilities as its originators is qualified to give an authoritative opinion regarding it. The theory is, an advance over old ways of thinking and cannot, therefore, be tested by any but the most advanced ideas.

Everyone will concede that there is a limit to the quantity of food that can be consumed with advantage. For example, everyone will concede that ten pounds a day is too much - or nine pounds, or eight pounds, and so on down; but in the descending scale there comes a point where a doubt as to the sufficiency of the amount will be justified. That this point, below which it is dangerous to reduce the consumption of food, can be determined by science, will hardly be disputed. Every investigation of the subject has endeavored to fix it. In the generally accepted "diet standards," the minimum quantities of food commonly consumed by man have been accepted as the minimum quantities required.

5 " Physiological Economy in Nutrition," p. 472.

"Within certain rather wide limits," says Professor Chittenden, "there is an apparent tendency for people of different nations, having a free choice of food and not restricted by expense, to consume daily approximately the same amounts of nutriments; to use what may be called liberal rather than small amounts of food; and lastly, to consume food somewhat in proportion to the amount of work done. It is perhaps, therefore, not strange that students of nutrition should have taken these results, obtained by the statistical method, as indicating the actual needs of the body for food, and that so-called 'standard diets' and 'normal diets' should have been constructed, based upon these and corresponding data. . . . These standards covering the quantities of food per day 'are intended to show the actual food requirements of persons under different conditions of life and work.' Here, however, lies an assumption which seems to meet with wide acceptance, but for which it is difficult to conceive any logical reason.

The thousands of dietary studies made on peoples all over the world, affording more or less accurate information regarding the average amounts of proteid, fat, and carbohydrate consumed under varying conditions, are indeed most interesting and important, as affording information regarding dietetic customs and habits; but the writer fails to see any reason why such data need be assumed to throw any light on the actual food requirements of the body. In the words of another, 'Food should be ingested in just the proper amount to repair the waste of the body; to furnish it with the energy it needs for work and warmth; to maintain it in vigor; and, in the case of immature animals, to provide the proper excess for normal growth, in order to be of the most advantage to the body.' (Benedict.) Any habitual excess of food, over and above what is really needed to meet the actual wants of the body, is not only uneconomical, but may be distinctly disadvantageous. . . With these thoughts in mind, may we not reasonably ask why it should be assumed that there is any tangible connection between the dietetic habits of a people and their true physiological needs? Arguments predicated on custom, habit, and usage have no physiological basis that appeals strongly to the impartial observer.

Man is a creature of habits; he is quick to acquire new ones when his environment affords the opportunity, and he is prone to cling to old ones when they minister to his sense of taste. The argument that because the people of a country, constituting a given class, eat a certain amount of proteid food daily, the quantity 50 consumed must be an indication of the amount needed to meet the requirements of the body, is as faulty as the argument that because people of a given community are in the habit of consuming a certain amount of wine each day at dinner their bodies must necessarily be in need of the stimulant, and that consequently alcohol is a true physiological requirement." 6

Accordingly, Professor Chittenden, actuated by his belief that what a man eats is no guide to what he should eat, has shown by a series of elaborate experiments, extending over long periods of time, that persons of widely varying habits of life temperament, and constitution, can maintain, and even heighten their mental and physical vigor, on far smaller quantities of food than these "minimum requirements" of the diet stand-ards. Since the point to be determined is the quantities of food men can live on, not what they do live on, it appears safe to assume that Professor Chittenden has come nearer than anyone else to determining the minimum food requirements of man.

6 Chittenden: "Nutrition of Man," pp. 157-159.

Secondly, everyone must concede that it is possible for science to ascertain the minimum requirement of man for proteid food, and also to ascertain whether the quantities of proteid in excess of this amount are of advantage or of disadvantage to the body. So far no one has been able to refute Professor Chittenden's conclusion, drawn from his elaborate experiments, that the quantities of proteid consumed by the average man are far in excess of the quantities assimilated, and that the excess of proteid not assimilated is of unqualified disadvantage to the body.

Thirdly, everyone will concede that it is possible for science to determine whether or not the complete mastication advocated by Horace Fletcher is of any specific value to the nutritive processes. So far all the scientists who have investigated the matter have been convinced that it is. The remarks of Elie Metchnikoff in his book, "The Prolongation of Life," which have been taken by some persons as a scientific refutation of the claims of Mr. Fletcher's theory, are of an extremely casual nature, and are based, not upon extensive investigations such as will be described in this book, but upon the statements of a single physician, who, in a small pamphlet, has published an account of his observations upon two persons suffering from an intestinal disease which he attributed to the fact that they gave an unusual amount of care to the mastication of their food. The remarks in question are as follows:

"The habit of eating quickly favors the multiplication of microbes around about the lumps of food which have been swallowed without sufficient mastication. It is quite harmful, however, to chew the food too long, and to swallow it only after it has been kept in the mouth for a considerable time. Too complete a use of the food material causes want of tone in the intestinal wall, from which as much harm may come as from imperfect mastication. In America, where Fletcher's theory took its origin, there has already been described, under the name of 'Bradyfagy,' a disease arising from the habit of eating too slowly. Einhorn, a well-known specialist in the diseases of the digestive system, has found that several cases of this disease were rapidly cured when the patients made up their minds to eat more quickly again. Comparative physiology supplies us with arguments against too prolonged mastication. Ruminants, which carry out to the fullest extent Mr. Fletcher's plan, are notable for extreme intestinal putrefaction and for the short duration of their lives. On the other hand, birds and reptiles, which have a very poor mechanism for breaking up food, enjoy much longer lives."7 Mr. Fletcher himself has pointed out that there is danger in carrying the practice of mastication to extremes.

Once the swallowing impulse has asserted itself, he says, there is no advantage in and there may be direct injury from attempting to hold the food in the mouth, even if it has not been reduced quite to the point of complete liquefaction and tastelessness.

7 Metchnikoff: "The Prolongation of Life." G. P. Putnam's Sons, New York.

Metchnikoff's statement that the ruminants are notable for intestinal putrefaction and shortness of life is at least open to question. The experiments of Dr. C. A. Herter with animals of all classes indicate that, while the bacteria in the intestines of the fast-eating animals (such as cats, dogs, lions, tigers and wolves) are of a deadly character, the bacteria in the intestines of the slow eaters (such as buffaloes, goats, horses and elephants) are practically harmless.8 And while it may be true that the lives of birds and reptiles are longer than those of ruminating animals, it has yet to be proved that the lives of fast-eating animals are longer than those of the ruminants.

The practical experience of everyone who has adopted the new plan supplies ample evidence that it is productive of only the best possible results. We have now to see that the reason it produces these good results is because it rests on a firm basis of scientific truth.

8 C. A. Herter, M. D.: "Character of the Bacterial Flora of Carnivorous and Herbivorous Animals," Science, p. 859, December 28. 1906.