Ranke, 1861

The large respiration chamber constructed by Pet-tenkofer and Voit in Munich was apparently used for the first time with man in June 1861, for a series of experiments carried out by Ranke upon himself and published by him.3 In these experiments the subject either fasted or was given an ordinary diet of undetermined nature, a mixed diet of known composition, or an excessive meat diet; the observations were all made in periods of 24 hours. The values are recorded in table 2.

Table 2. - Carbon-Dioxide Production In Fasting And Food Experiments (Ranke)

Ranke's experiments are referred to in a subsequent publication by Pettenkofer and Voit,4 the statement being made that Ranke found in 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 maximum 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 work1 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.

1Smith, Phil. Trans.. 1S59, 149, p. 717.

2Ibid., p. 712.

3Ranke, Arch. f. Anat. Physiol., 1862, p. 311.

4Pettenkofer and Voit, Ann. der Chem. u. Pharm., 1862-63, Suppbd., 2, p. 53.

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 nutriment, 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, Berg3 made a large number of experiments on himself. In these experiments he employed a mouthpiece, absorption vessels, gas-meter, Muller valves, and the Pettenkofer method for determining the carbon dioxide. Special emphasis was laid upon voluntary alteration of the type of respiration which, as we know to-day, affects most the values for the carbon-dioxide production. Nevertheless, taking into consideration only his carbon-dioxide measurements, he finds interesting values before and after food which should be noted here. Thus the carbon-dioxide production per 15 minutes, when the respiration rate averaged 15 per minute, was during fasting 8.819 grams; after a rich meal it increased to 9.960 grams, an increment of 1.141 grams, or approximately 12 per cent. An increase was also noted in the pulse rate from 65 beats per minute during fasting to 71 beats per minute after a rich meal. In the average of the experiments with normal uncontrolled respiration rate the value during hunger for the carbon-dioxide production per 15 minutes was 4.866 grams and after a rich meal 6.613 grams, an increment of 1.747 grams or about 36 per cent. The pulse rate increased from 52.4 to 61.3 per minute.

1Ranke, Die Ernahrung des Menschen, 1876, p. 167. 2Pettenkofer and Voit, Zeitschr. f. Biol., 1866, 2, p. 459. 3Berg, Deutsch. Arch. f. klin. Med., 1869, 6, p. 291.

In one interesting series of experiments, the effect of water-drinking was studied. When the respiration rate was adjusted at 15 per minute Berg found practically no increase in the carbon dioxide produced with water as compared with the values found during thirst. A decrease of 3 beats per minute in the pulse rate was observed. With normal uncontrolled respiration the carbon-dioxide production increased from 5.115 to 6.519 grams per 15 minutes after water, an increment of 1.404 grams or approximately 27 per cent; the pulse rate decreased 5.8 pulse beats per minute. The author concludes that when experiments are made hourly from 7 a. m. to midnight the energy of all the respiratory functions increases after meal times. The maximum is observed 2 hours after the morning meal and 3 hours after the afternoon and evening meals. These values pertain to the experiments in which the respiration rate was controlled. With uncontrolled respiration the maximum values were noted immediately after each meal. It is clear that the artificial regulation of respiration greatly affected the values found by Berg. The results of his experiments are of interest only in substantiating practically all previous work to the effect that the increment due to the ingestion of food may be from 20 to 35 per cent.