So also our overeating is largely an unscientific effort to compensate for overconcentration of diet,—that is, an effort to get bulk. Again, too much protein is in large measure due to the need of compensating for rapid eating, for as has been remarked, protein is the one kind of food which can be eaten fast with impunity.

Again, a large part of our moral derelictions is due to an unbalanced life from which amusements are largely omitted. The “bad” boy in the city streets is usually following his instinct for amusement, of which the lack of playgrounds has deprived him. Dissipations of many kinds are explained in a similar way. It is largely because workmen are so often drudges and lack normal recreations that they seek amusement in the concentrated form they find in saloons, gambling places, dives and dance halls.

Finally those economic and social conditions of civilization which have resulted in deferring marriage beyond the best physiological age, lie behind prostitution and its terrible train of consequences including the venereal diseases.

The combined effects of all the unhygienic modes of living are undoubtedly greatly to shorten human life. Most other mammals live about five times the growing period. In man, this would mean that the normal life-span should be about a century and a quarter, an age which is now reached only in one case out of millions.

The object of this book is primarily to instruct the individual as to what he can do to maintain his own individual health. But individual hygiene is only one particular branch of hygiene, and it is well for the individual, partly out of public spirit, partly in self-defense, to have some idea of the other important branches, namely, public hygiene, the hygiene practised by the health officer, semipublic hygiene, the hygiene of schools, institutions, and industrial establishments, and race hygiene or eugenics, the most important of all.

Public hygiene has made much progress during recent years. In consequence, the number of deaths from the acute or infectious diseases has been greatly diminished. Health officers are beginning to demonstrate the truth of Pasteur’s words, “It is within the power of man to rid himself of every parasitic disease.”

It is therefore incumbent on the individual to contribute his share to the hygienic work of society as a whole, in particular to take an active interest in health legislation and administration. A man can not live to the best advantage in a life isolated from all social obligations, any more than could Robinson Crusoe, who was unable to launch his canoe in the ocean, after he had been at great pains to construct it, because he had no one to help him. Each man should take part in the great social hygienic struggle, if he is to reap the highest rewards in his own personal hygienic struggle. And he can do a great deal if he will be patient and persistent. If, for instance, he would always insist on suitable air conditions in public buildings, electric cars, theaters, and churches, and encourage others to do so, it would not take long to make air reform general.

We need to concern ourselves particularly with the character of our public water supply, air supply and food supply, the number of bacteria in milk, the fitness for human consumption of the meat, fowl, fish, and shell-fish sold in the public markets, and the use of adulterants and preservatives in canned and bottled goods.

Vaccination is now a known preventive against smallpox, typhoid fever, and other germ maladies. Its use should be advocated and the ignorant prejudice against it should be overcome.

Last but not least, the individual should cooperate in the great movement against the social evil.

As soon as an individual becomes interested in caring for his own health and for the health of his family, his interest will not cease at individual hygiene; he will wish to improve the efficiency of the public health service by increased appropriations, improved equipment and personnel; and to cooperate with the health officer.

First, we can carry through life uninjured the essential germ plasm which has been entrusted to our care. We should never forget that this germ plasm, which we receive and transmit, really belongs, not to us, but to the race; and that we have no right, through alcoholic or other unhygienic practises, to damage it; but that, on the contrary, we are under the most solemn obligation to keep it up to the highest level within our power. We are the trustees of the racial germ plasm that we carry.

For society as a whole, a thoroughgoing eugenic program must include:

(1) The prevention of reproduction by the markedly unfit, such as the feeble-minded, by sterilization of the most unfit and by segregating the remainder in public institutions.

(2) The enactment of wise marriage laws.

(3) The development of an enlightened sentiment against improper marriages and the putting at the disposal of individuals contemplating marriage the data accumulated and principles worked out by eugenic students.

The Eugenics Record Office of Cold Spring Harbor, Long Island, N. Y., is now engaged in collecting such material.

It will help to balance the ration and to avoid an excess of protein and also to avoid a deficiency of either fat or carbohydrate, if we take a bird’s-eye view of the various common foods in respect to the protein, fat and carbohydrate they contain. For this purpose the following table has been constructed.

COMMON FOODS CLASSIFIED

The compartment farthest to the right contains a list of those foods “very rich in fat.” The two compartments next to the left contain those “rich in fat,” and the three compartments to the extreme left contain those “poor in fat.”

With reference to carbohydrates (starch or sugar), we can say that the foods in the lower left compartment are very rich in carbohydrate. Those in the two neighboring compartments (the one beginning “shell-fish” and the one beginning “peanuts”) are moderate, and those in the remaining compartments are those poorest in carbohydrate.

An ideal proportion of the three food elements is to be had only in the middle compartment of the lowest row. But it is by no means necessary or advisable to confine one’s diet to the few foods which happen to fall in that compartment, provided foods chosen from other compartments balance each other. Thus, fruit and nuts balance each other, the one being at the left and the other at the right of the ideal compartment. In the same way, potatoes and cream balance each other, as do bread and butter. Instinctively these combinations have been chosen, especially bread and butter. This combination is, however, slightly too low in protein, and a better balance is obtained by adding a little from the compartment vertically above the ideal. In this way we obtain the familiar meat-, egg-, or cheese-sandwich, constituting of itself a fairly well-balanced meal.

The following more detailed and specific table of food values will prove helpful to those who desire intelligently to balance their diet or to provide balanced menus for their families. A very little attention to this subject will enable one to acquire sufficient knowledge of dietetic needs to successfully govern the diet in a general way without weighing or measuring the food. In the following table the number of calories available in ordinary food portions is stated. Such a table should not, of course, be memorized, but an occasional reference to it will enable one soon to acquire a working knowledge of the food values of the main articles in the dietary.