FOODS WHITMAN IsTTTTBITION. 165 



subject, others with dogs. The experiments were planned to show the coefiB- 

 cient of utilization (Abnut zungsquote) of nitrogen metabolism, the demands 

 of the body for nitrogen during muscular work, and the prevention of the forma- 

 tion of excessive protein in the circulation when meat was gradually added to 

 a nitrogen-free diet. The physiological nitrogen minimum was determined with 

 a carl)ohydrate diet, a fat diet, and a nitrogen-free diet to which nitrogen was 

 gradually added. 



The author concludes that the physiological nitrogen minimum under given 

 conditions is determined by 3 factors, the biological value of the protein in the 

 food (i. e., its power of replacing cell substance), the storage of protein (i. e.. 

 In the cells and circulation), and the extent of the energy exchange in the body. 

 The physiological nitrogen minimum equals the coefficient of ultilization when 

 the nitrogen of the food and that of the body are quantitatively the same, when 

 the storage of protein is prevented by the gradual addition of ingested protein, 

 and wheu the conditions of comparative experiments, with nitrogen starvation 

 and with the ingested nitrogen just sufficient to maintain the nitrogen balance, 

 are such that the energy requirement of the body remains unchanged. 



[The gaseous exchang'e and metabolism in a diet poor in nitrogen], N. 

 ZuNTZ and P. Schirokich (Separate from Med. Klinilc, 1912, No. 32, pp. 5). — At 

 a meeting of the Physiological Society of Berlin, June, 1912, the senior author 

 reported metabolism experiments carried on in his laboratory with a subject 

 who had for 3 months been living on a diet of potatoes and butter, and who 

 advocates prolonged chewing and insalivation as a means of increasing the 

 percentage of food material digested and decreasing the energy required for the 

 processes of digestion. 



There were 2 experiments, the first of 5 and the second of 9 days' duration. 

 All ingested and excreted materials were measured and the gaseous exchange 

 and body heat were determined. In the first experiment, the daily ration con- 

 sisted of 1,500 gm. of potatoes and 150 gm. of margarin, yielding 5.35 gm. of 

 nitrogen and 2,750 calories of energy. In the second experiment, the amount of 

 potatoes consumed averaged 1,101 gm., with 150 gm. of butter, but toward its 

 close isodynamic amounts of bacon fat and tomato puree were substituted for 

 part of the butter, the total daily ration yielding on the average 4.415 gm. of 

 nitrogen and 2,116 calories of energy. 



During the first experiment, 77.2 per cent of the nitrogen was digested, 95.2 

 per cent of the energy was available, and there was a daily average loss of 0.50 

 gm. of nitrogen from the body. During the second experiment, the coefficient of 

 digestibility for nitrogen was 76.4 per cent, the availability of energy 94.6 per 

 cent, and the average nitrogen loss 0.9G2 gm. per day. As Rubner's figures for 

 the digestibility of nitrogen and availability of energy in potatoes are 80.5 per 

 cent and 95.4 per cent, respectively, the investigators do not find that the 

 peculiar method of insalivation produces the effect claimed by the subject, or 

 that the diet was sufficient to maintain the nitrogen balance. 



The energy expended in 24 hours per kilogram of body weight was 19.19 

 calories in the first experiment and 19.33 calories in the second, figures very 

 similar to those obtained by Atwater and Benedict with fasting subjects during 

 rest experiments in the respiration calorimeter, namely, 20.9 and 20.0 calories. 

 During part of the first experiment there was slight fever and considerable 

 restles.sness, and the figures obtained for gaseous exchange and the calorimetric 

 measurements are, therefore, unsatisfactory. 



The body without food gave off 1,471 calories In 24 hours. The amount of 

 food taken in 24 hours supplied 2,002 calories. The difference between these 

 two, 531 calories, is the amount available for digestive work and muscular 

 activity. In the first experiment the quantity was even larger. The food sup- 



