In the study and pursuit of menticulture the author has found that working for the common good is as necessary to happiness as working for self, and that the retroactivity and reciprocity of the idea multiplies the profits indefinitely. The sequence of profitable, altruistic interrelation is stated in the “Explanation” of the chain of the A. B. C. Life Series, of which this book is one of the links. * * * * * Aside from those actively engaged in the several investigations to whom reference is often made, the author wishes to express special gratitude to Sir Michael Foster and to Professor Henry Pickering Bowditch of the Board of Scientific Assessors. Unselfish and unremitting in their assistance and encouragement, the author’s work has been made easy since their interest was enlisted. Sir Michael, as Member of Parliament in England, and as a physiological savant, knows that economic nutrition is the key to England’s welfare, as well as the basic necessity of temperance, morality, health, and efficiency, as is expressed in the two documents from him reproduced in the “Report of a Plan for an International Investigation into the Subject of Human Nutrition” and in his “Note” on the Cambridge examination of the author and Dr. Van Someren at Cambridge University laboratories, given herein. Professor Bowditch, as a distinguished physiologist, publicist, and especially as the President of the Children’s Aid Society, of Boston, Massachusetts, often mentioned as the model institution of its kind in the world, realises that the effort of the author to secure basic knowledge relative to right nutrition, adaptable to kindergarten teaching and home training during the impressionable period of youth, is of the greatest importance in social reform. A trial suggestion relative to ways and means of _beginning right_ with _all the children_ and thus insuring a regeneration of the classes most in need of reform, in not longer than two decades, is outlined in the author’s appeal for the waifs of society, entitled “That Last Waif; or Social Quarantine.” Whenever there is any disposition to slack up in patience or enthusiasm to accomplish the ultimate end aimed at, the picture of the waif in that story is flashed back by memory, and there can be neither forgetfulness, indifference, nor repose until “that last waif” has been given _at least a chance of choosing_ between the right and the wrong, the good and the bad. POSTINTRODUCTORY [Just before “going to press” the author has received a letter from his esteemed colleague, Dr. Hubert Higgins, giving the gist of interviews with an eminent European physiologist and with a famous American chemist and dietitian, which so well describes the attitude of the scientific mind towards the problem of human nutrition that the scientific mentor of the writer advises its addition to the book.