146 METABOLISM AND NUTRITION 



teid. Finally, it is possible that in certain diseased conditions, meat would be 

 harmful, and that some persons have a positive aversion to it. 



If, therefore, the individual get a sufficient supply of proteid and fat in 

 other articles of diet, like cheese and butter, so that great bulkiness can be 

 avoided, meats are not absolutely necessary. But from the standpoint of the 

 physiology of nutrition, there is no reason for avoiding them. 



Against the claim that the vegetable foods constitute the natural i. e., the 

 original diet of man this additional objection can be raised: the most im- 

 portant of the vegetable foods, namely the cereals, are subject to the action 

 of the digestive fluids only after thorough preparation; whereas man had 

 lived a long time on the earth before he had progressed so far as to under- 

 stand how to cultivate the soil, cook his food, grind his grain and bake bread. 

 Meat, however, requires no further preparation for eating than to be divided 

 into small pieces. We have reason, therefore, for claiming rather that man 

 was originally carnivorous. 



There are those who would have us believe that the really natural diet of 

 man consists of fruits. But it is not a very easy matter at best to get proteid 

 and fat enough from fruits, and besides, in many inhabited lands it is quite 

 impossible to raise any fruits or any kind of vegetable foods in large enough 

 quantities to provision the population, 



Our conclusion is that the diet most generally suitable for man is a mixed 

 diet, composed of both animal and vegetable foods. It is only by reason 

 of his ability to utilize all sorts of foods that it has been possible for man 

 to people the entire earth from the equator to the poles. 



REFERENCES. Armsby, "Principles of Animal Nutrition," New York, 1903. 

 Atwater and others, U. S. Dept. of Agr., Office of Experiment Station, Bul- 

 letins Nos. 44, 63, 69, 109, 136. Atwater and Benedict, "A Respiration Calo- 

 rimeter, with Appliances for the Direct Determination of Oxygen," Publications 

 of the Carnegie Institution of Washington, No. 42, 1905. R. H. Chittenden, 

 "Physiological Economy in Nutrition," New York, 1905. Otto Folin, "A 

 Theory of Protein Metabolism," in American Journal of Physiology, XIII, 1905. 

 Robert Hutchinson, "Food and Dietetics," 2d edition, New York and London, 

 1906. Ludolf Krehl, " Pathologische Physiologic," Leipzic, 1904. Graham Luslc, 

 "Elements of the Science of Nutrition," Philadelphia, 1906. 7. MunJc and 

 C. A. Ewald, " Die Ernahrung des gesunden und kranken Menschen," 3d edi- 

 tion, Wien and Leipzic, 1896Pfluger, " Glycogen," 2d edition, Bonn, 1905. 

 Rubner, " Energieverbrauch," Leipzic and Wien, 1902. C. Voit, " Physiologic 

 des allgemeinen Stoffwechsels und der Ernahrung " (Hermann's Handbuch d. 

 Physiologic, VI, 1), Leipzic, 1881. 



