Recurring now to the experiments made with dogs, there is certainly suggested an element of danger in a low proteid diet, which, if the experiments are taken at their face value and the conclusions derived therefrom applied to man, needs careful consideration. Jägerroos plainly was not inclined toward the belief that a low nitrogen intake was the cause of the unfortunate results that attended his experiments. Still, his animals did die from some cause, and thereby his position was weakened. Munk and Rosenheim, on the other hand, from their experiments were apparently convinced that a low proteid intake was inimical to dogs, and it will be remembered Rosenheim concluded that “a daily ration containing even 0.32 gram of nitrogen per kilogram of body-weight, and with a fuel value of 110 calories per kilo, is not sufficient to maintain the animal in a condition of health.” If this is really true, there is some ground for the arguments advanced by critical writers regarding the general subject of nitrogen requirements of man. The evidence and the arguments, however, have always seemed to the present writer frail and faulty; but recognizing the hold they have taken on physiologists and the way they are usually applied to man, I have attempted to test the matter experimentally under conditions which would yield trustworthy and conclusive results. The question how far results obtained with dogs can be applied safely to man may be open to discussion, but we must first be sure of our facts before arguments or conclusions of any kind are warranted. It is to be remembered that dogs are as sensitive in many ways as man, and no physiological experiment covering a long period of time can be carried out with any hope of success unless there is due regard for proper hygienic conditions, some degree of variety in diet, and reasonable opportunities for fresh air and occasional exercise. I fancy that even the most vigorous and hardy man, if confined for six consecutive months in a room just large enough to furnish requisite air-space and to permit of extending his body at full length, would find himself at the end of such a period in a condition far from healthful, even though there were perfect freedom of choice in diet. If, however, there were added to the above conditions monotony in diet extending through many months, there would be no occasion for surprise if the individual lost appetite and strength, and showed signs of disturbance of the gastro-intestinal tract.