332 HUMAN BIOLOGY 



After 1865 there was an era of enthusiasm for the study, 

 with both human and animal subjects, of the protein 

 requirements and energy requirements of the individual 

 as influenced by age and condition of Hfe. Such studies were 

 carried on by Prof. Carl Voit of Munich, and his students 

 extended his studies in many countries. W. A. Atwater was 

 the great exponent of nutrition work of this kind in the United 

 States prior to 1 900. He thought that nutrition would be placed 

 upon a strictly scientific basis when all the ordinary foodstuffs 

 had been analyzed chemically, their energy values and 

 digestibility determined, and the cost of production of each of 

 our important farm crops had been studied. Atwater spent the 

 active period of his life in the collection of data along these 

 lines. 



The results of the chemical analysis of foods showed 

 striking differences in their composition. Meats, eggs, and 

 the flesh of poultry and fish consist in great measure of 

 water, protein, fat and inorganic salts. Milk in a dry state 

 contains in addition to a large amount of protein much 

 carbohydrate (milk sugar) and a relative abundunce of fat 

 as well as the various inorganic elements found on the 

 ashing of an animal body. Among the vegetable foods, peas 

 and beans contain extraordinary amounts of proteins, very 

 little fat, but a moderate amount of carbohydrate, and an 

 ash of characteristic composition. Cereal grains contain 

 much less protein and relatively much more carbohydrate 

 and starch, and but a little fat. The nuts, with the 

 exception of the chestnut which contains starch, 

 contain almost no carbohydrate, large amounts of protein, 

 and are exceedingly rich in fats. Fruits and some of the 

 tuber and root vegetables are exceedingly rich in water, 

 so that in the form in which they are ordinarily purchased 

 their energy and protein values appear quite low in contrast 

 with many other foods. It is not surprising that in the era 

 of enthusiasm over the analysis of foods, the striking differ- 

 ences in composition should have raised great expectations in 

 the minds of investigators concerning their ultimate value in 

 the planning of diets. Atwater cherished the hope that 

 when his elaborate plan of study was complete it would 

 be possible to advise the housewife concerning the most 



