18 FOOD INGESTION AND ENERGY TRANSFORMATIONS. 



hunger 660 grams of carbon dioxide per 24 hours, and with the richest 

 food 860 grams. Although the fasting value given by Pettenkofer and 

 Voit agrees approximately with Ranke's values (see table 2), the maxi- 

 mum value of 860 grams is considerably less than the 925.6 grams 

 reported by Ranke. Using 660 grams as a basal value, it is seen that 

 the ordinary diet and the mixed diet of known composition increased 

 the metabolism approximately 130 and 100 grams i. e., about 20 per 

 cent while the rich meat diet increased it nearly 200 grams and the 

 maximum diet approximately 260 grams, or about 33 and 40 per 

 cent respectively. Ranke's experiments are particularly interesting 

 as representing the first 24-hour experiments made with man. They 

 were carried out with the precautions and beautiful technique which 

 characterize all the work done with this large apparatus by Pettenkofer 

 and Voit, and which completely revolutionized knowledge regarding 

 the energy transformations and gaseous metabolism of man. In a later 

 presentation of his earlier work 1 Ranke has expressed his values in the 

 terms of calories per 24 hours, giving approximately 2,000 calories 

 for fasting, 2,300 calories for ordinary diet, and 2,800 calories for a 

 rich meat diet. 



Pettenkofer and Voit, 1866. A series of 15 experiments, each 24 

 hours long, and made with the large respiration chamber in Munich, 

 was reported by Pettenkofer and Voit. 2 Of 12 rest experiments, 3 were 

 fasting, 4 were with an average diet, 2 with a protein-rich diet, 2 with 

 a protein-free diet, and 1 with the same diet given in the morning and 

 again in the evening. The average carbon-dioxide production per 24 

 hours during fast, with the subject used in most of the experiments, was 

 717 grams. With a mixed diet the carbon-dioxide production increased 

 to 928 grams, an increment of 29 per cent. With a protein-rich diet 

 the authors found that the carbon-dioxide excretion increased to 1,020 

 grams, which is approximately 10 per cent greater than that found 

 with the mixed diet, but 42 per cent above the fasting value. Although 

 the authors discuss the increments in the oxygen consumption, the 

 errors in the method of indirect determination used make their results 

 of questionable value. If no allowance is made for the change in the 

 character of the materials burned under the various conditions of nutri- 

 ment, we may summarize their results by stating that the ingestion 

 of a mixed diet produced an increment in metabolism of about 30 per 

 cent, and with a protein-rich diet resulted in an increment of about 40 

 per cent. 



Berg, 1869. Using an entirely different type of apparatus, Berg 3 

 made a large number of experiments on himself. In these experiments 

 he employed a mouthpiece, absorption vessels, gas-meter, M tiller valves, 



'Ranke, Die Ernahrunn des Menschen, lfS76, p. 107. 

 "Pettenkofer and Voit, Zeitschr. f. Biol., 1866, 2, p. 459. 

 3 Berg, Deutsch. Arch. f. klin. Med., 1869, 6, p. 291. 



