At Yale University, Professor Russell H. Chittenden, Director of the Sheffield Scientific School, Lafayette B. Mendel, Professor of Physiological Chemistry, and Irving Fisher, Professor of Political Economy, have carried on a long series of experiments, begun six years ago as a test of the claims made by Fletcher. The net results of these experiments up to date (for they are still in progress) may be put into a nutshell. The following statement was drawn up by one of the writers of this book and submitted to Professors Chittenden and Fisher, who have accepted it as a summary of their present views: “The commonly accepted standards which claim to tell the quantity of food needed each day by the average man are based upon many careful observations of what men actually do eat. “We challenge these standards, however, as the exact science of to-day cannot accept as authority common customs and habits in any attempt to ascertain the right principles of man’s nutrition, since experiments have demonstrated how readily one set of habits may be substituted for another and how easily wrong habits become hardened into laws. The evidence presented by observers of common customs, while they must be duly considered, cannot, therefore, be taken as proof that these habits and customs are in accord with the true physiological needs of the body. “We believe that the following propositions have been demonstrated as truths by the experiments we have made at Yale. “People in general eat and drink too much. “Especially do they eat too much meat, fish and eggs. “This is so because meat, fish and eggs are the principal proteid-containing foodstuffs. [Illustration: PROF. RUSSELL H. CHITTENDEN, PH.D., LL.D., SC.D., Director Sheffield Scientific School, Yale University. He has conducted many dietary experiments from the physiologist’s point of view.] “Proteid is an essential food element, absolutely necessary for the upbuilding of tissue, for the maintenance of life. It is one of three main elements into which all foodstuffs may be divided—the others being Carbohydrates (the sugars and starches) and Fat. While it is indispensable, it is also the element which the body machinery finds most difficult to dispose of. Proteid is ‘nitrogenous.’ Nitrogen is never wholly consumed in the body furnace as fats, sugars and starches are. There is always solid matter left unconsumed, like clinkers in a furnace; which clinkers the kidneys and liver have to labor to dispose of. If the clinkers are produced in excess of the ability of these organs to handle them without undue wear and tear, damage of a serious, and sometimes permanent, nature follows. The ideal amount of proteid is the amount which will give the body all of that substance which it needs without entailing excessive work upon the body machinery.