On February 9, the diet was changed by returning to 70 grams (2 1/3 oz.) of meat, 158 grams (5 1/3 oz.) of cracker dust, and 60 grams of lard, with a daily intake of 0.28 gram of nitrogen per kilo of body-weight.

"In this manner, the experiment was continued with frequent changes in the character of the diet, but always maintaining essentially the same value in nitrogen and calories as shown in the table, until June 27; having extended through just eleven months, with the animal at the close of the experiment still gaining in body-weight, with a steady plus balance of nitrogen, and with every indication of good health and strength. For ten months the animal lived with perfect comfort and in good condition on an average daily intake of 0.26 gram of nitrogen per kilogram of body-weight, and with an average fuel value of 70.3 calories per kilo. Further, it is to be observed that at no time during the ten months did the daily intake of nitrogen rise above 0.28 gram per kilo, while during one month it fell 0.23 gram per kilo.

Similarly, the fuel value of the daily food never exceeded 73 calories per kilo, while at times it dropped as low as 67 and 65 calories per kilo. That this diet was more than sufficient, both in nitrogen and fuel value, is indicated by the steady increase in body-weight and by the plus nitrogen balance observed in most of the periods throughout the experiment. Indeed, with the comparatively low degree of muscular activity which this animal was accustomed to, it would have been unwise to have kept the subject much longer on a diet so rich as the above, since there would have been danger of detriment to its health and good condition."11

Professor Chittenden's conclusion from these experiments is as follows: "These experiments on the influence of a low pro-teid diet on dogs, as a type of high proteid consumers, taken in their entirety, afford convincing proof that such animals can live and thrive on amounts of proteid and non-nitrogenous food far below the standards set by Munk and Rosenheim. The deleterious results reported by these investigators were not due to the effects of low proteid or to diminished consumption of non-nitrogenous foods, but are to be ascribed mainly to non-hygienic conditions, or to a lack of care and physiological good sense in the prescription of a narrow dietary not suited to the habits and needs of this class of animals. Further, it is obvious that the more or less broad deductions so frequently drawn from the experiments of Munk and Rosenheim, especially in their application to mankind, are entirely unwarranted and without foundation in fact. Our experiments offer satisfying proof that not only can dogs live on quantities of proteid food per day smaller than these investigators deemed necessary, and with a fuel value far below the standard adopted by them; but, in addtion, that these animals are quite able on such a diet to gain in body-weight and to lay by nitrogen, thereby indicating that even smaller quan-titles of food might suffice to meet their true physiological requirements." 12

"Nutrition of Man," pp. 244-248.

Further experimental evidence in the investigation of both Mr. Fletcher's claims for mastication and Professor Chittenden's claims for a deliberately restricted proteid diet, has been contributed by Professor Irving Fisher, professor of political economy at Yale, who, as a political economist, has been interested in testing the alleged effect of the new system of diet upon a man's output of work.

Professor Fisher's first experiment was upon nine Yale students, in vigorous health and of ordinary student occupations, and lasted twenty weeks. The men were instructed to follow their own tastes in choosing the character and amount of the food taken, but were asked not to eat until they were equally hungry and then to masticate both solid and liquid food until it was involuntarily sucked down into the throat.

12 Chittenden: "Nutrition of Man," pp. 263-261.

The experiment is thus described by Professor Fisher:

"Two years later," (than the experiments upon Mr. Fletcher), "in 1906, nine Yale students under my direction experimented with Mr. Fletcher's method of instinctive eating. Careful records were taken of the amounts of food consumed and the proportions of proteid, fat and carbohydrate (starch and sugar) used. In order to avoid the annoyance of weighing the food at the table it was all weighed in the kitchen and served in definite portions of known food value. From these records the proportions of proteid, fat and carbohydrate were worked out by means of a Mechanical Diet Indicator, which I have described in The American Journal of Physiology and The Journal of the American Medical Association. Records were made for each man and each day during the five months of the experiment. It was found that the proteid element was gradually and unconsciously reduced. During the second half of the experiment this reduction was somewhat accelerated by suggesting to the men that when appetite was in doubt they should give the benefit of that doubt to low proteid non-flesh foods: but the men were never encouraged to choose any food when their instinct definitely preferred another.

"The main lesson from the experiment, however, was that the men improved in health and physical endurance. By actual gymnasium tests it was found that the physical endurance of the men was approximately doubled in five months. . . . Only one of the men failed to improve in endurance, and this exception proved the rule, for he was the only one of the nine who was not thorough in his practice of mastication, nor did he, in consequence, reduce his flesh foods as much as did the other experimenters. The majority of the men who took part in the experiment have become enthusiastic, have continued to 'Fletcherize,' and have taken up physical culture in all of its branches." 13

13 Fisher: The Independent, New York, August, 1907.