DU BOIS: BASAL ENERGY REQUIREMENT OF MAN 349 



is lost, for the law of the conservation of energy applies to the 

 animal organism. 



Meanwhile Zuntz and his pupils were making very important 

 contributions to the science, using an apparatus which collected 

 the expired air during periods ten to twenty minutes long. They 

 were the first to grasp the importance of the modern standard 

 conditions used in determining the basal metabolism. Their 

 subjects were studied in the morning before breakfast, lying re- 

 laxed on a couch. Magnus-Levy examined a large number of pa- 

 tients in this manner and made great advances in our knowledge 

 of the metabolism in disease. Zuntz, Loewy, and Durig used a 

 portable apparatus in the study of the physiology of walking 

 and other forms of muscular exercise. 



America's greatest contribution to the science of nutrition was 

 the Atwater-Rosa calorimeter, devised in Middletown, Con- 

 necticut. This was a small chamber about the size of a ship's 

 state-room, equipped with a folding bed, a chair, a table, and a 

 stationary bicycle. In it a man could live for a week or two, 

 comfortably, but perhaps monotonously. His heat production 

 was measured in two different ways. First, by the method of 

 direct calorimetry, which determined by physical methods the 

 heat of vaporization and of radiation and conduction; second, 

 by analysis of the oxygen consumption and carbon dioxid pro- 

 duction the grams of protein, fat, and carbohydrate oxidized each 

 hour, this being the method of indirect calorimetry. Results 

 obtained by these entirely different methods agreed perfectly. 

 Atwater and his associates, Rosa and Benedict, established the 

 fact that the law of the conservaton of energy applied to man. 

 They also made important contributions to our knowledge of the 

 utilization of foods, and of the dietary requirements under vari- 

 ous circumstances. After the retirement of Atwater two groups 

 of his assistants carried on his work. Langworthy and Milner 

 moved with the famous calorimeter to the Department of Agri- 

 culture in Washington. Benedict and Carpenter built several 

 new calorimeters and established in Boston the Nutrition Lab- 

 oratory of the Carnegie Institution of Washington. Here they 

 have not only made great advances in technique but have also 



