In the first half of the experiment the men held their own on about 40 per cent. less food, computed by cost, and increased their strength-endurance ability by something more than 100 per cent., with the added felicity of feeling unusually fit all of the time, entirely escaping the slack or sick spells they had been accustomed to, and improving greatly in their general studentability, that is: power of concentration, memory, mental comfort, profundity of sleep, etc. During the second half of the experiment still more improvement was secured owing to the readiness of the body to accommodate itself to the wish by favouring the economies. I have not a copy of the report at hand. It is included in the publications of Yale University about 1905. [Illustration: THE AUTHOR, ON HIS SIXTIETH BIRTHDAY, PERFORMING FEATS OF AGILITY] [Illustration: AND STRENGTH WHICH WOULD BE REMARKABLE EVEN IN A YOUNG ATHLETE.] While all of the abundance of confirmatory evidence which has accumulated since 1898 is valuable and gratifying, the verdict of the unremitting observation since then is that the problem of nutrition is always a personal one. After fifteen years of devotion to the study of the head-end question, with due attention to the tell-tale excreta and the product expressed in terms of energy and general comfort, I am unable to predict what my body is going to want to-morrow in the way of nutrition supply. I can say with some confidence that if I go on doing as I have been accustomed to doing daily, and no shock of grief or surprise intervenes to upset all calculations, I am likely to find nutritive satisfaction as expressed by appetite among the foods that are commonly agreeable to me. If I am compelled or impelled to do a great stunt of walking or other unusual exertion, or receive crushing news, all my present predictions may be useless. The body itself, from the hair on the head to each finger or toe-nail will know what it wants and will have given to the caterer Appetite its requisition covering the need. In the meantime each brain cell and all of the bones have not been neglectful of their sustenance requirements, nor have they been backward in letting Appetite know.