Cronheim, 1905

Employing the Zuntz-Geppert technique, Cron-heim2 reports the study of the influence of a highly nitrogenous (81.2 per cent protein) preparation, somatose, upon the metabolism. He concludes that the increased metabolism after somatose, designated by him in accordance with the usage of the Zuntz school as Verdauungsarbeit, is less than that after meat containing a corresponding amount of nitrogen. A number of meat experiments are reported in which he finds that after 130 grams of meat the increase in the oxygen consumption in 7 hours equals 5,790 c.c, corresponding to a total energy output of 27.73 calories, or 20.9 per cent of the energy value of the meat. With an amount of somatose containing as much nitrogen as the 130 grams of meat, he finds that the increase was but 9.29 per cent of the energy of the ingested material. With meat the main increase in metabolism occurred in the second to the fourth hour, but with somatose it did not occur until later. These time relations were likewise observed in the rate of excretion of nitrogen in the urine.

Johansson, 1908

In 1908 Johansson3 made another important contribution to the study of the influence of carbohydrates upon metabolism. Using the Sonden-Tigerstedt respiration chamber in Stockholm with a large number of subjects, he made experiments with various sugars and accurately determined the increment in the carbon-dioxide production. It is greatly to be regretted that Johansson's most valuable discussion could not have been based upon measurements of the oxygen consumption made simultaneously with the carbon-dioxide measurements. In this way a suggestion could have been obtained as to the probable relationship between the three factors which may enter into such a carbon-dioxide increment, i. e., first, the substitution of a katab-olism consisting mainly if not exclusively of carbohydrate; second, an excess of carbon dioxide produced in the transformation of the excess carbohydrate into fat; and third, the actual increment in the carbon-dioxide production due to an increased total metabolism. Although Johansson did not take into account all of these three factors, certain of his conclusions are important.

1Johansson, Billstrom. and Heijl, Skand. Arch. f. Physiol., 1904, 16, p. 263. 2Cronheim, Arch. f. d. ges. Physiol., 1905, 106, p. 17. 3Johansson, Skand. Arch. f. Physiol., 1908-09, 21, p. 1.

An increment in the carbon-dioxide production was found with all sugars, this being greatest with levulose and sucrose and least with dextrose. For each sugar the maximum increase was obtained with about 150 grams; the length of the increase never exceeded 6 hours, which corresponds to the time required for the passing of food through the small intestine. Levulose gave twice as great an increase in the carbon-dioxide excretion as did the same amount of dextrose. Johansson contends that the increase in carbon dioxide after the ingestion of sugar can not be satisfactorily explained on the assumption of a Verdauungsarbeit. The maximum capacity of the intestine for absorbing sugar averages about 80 grams per hour. The maximum carbon-dioxide output following the feeding of cane sugar and levulose was about 35 grams per hour, with a basal value of 22 grams. With dextrose and milk sugar the increment was only about one-half that with the other sugars. A series of experiments in which sugars were given with varying amounts of water led Johansson to the conclusion that the ingestion of water played no role in the metabolism, since the increase in carbon dioxide was entirely independent of the amount of water consumed.

Staehelin, 1908

In a series of observations on an obese individual, Staehelin,1 using the Zuntz method for determining the oxygen consumption and carbon-dioxide production, found that the increment after eating meat was very much less than that found with normal individuals. He reports 3 experiments nuchtern, 2 experiments with a meat diet, 2 with a diet of cabbage, potatoes, and apples, and 2 with bacon, bread, and butter. Staehelin concludes that the vegetable diet, because of the increased work of digestion, results in an increase in the oxygen consumption, while a cellulose-poor diet (fat diet) has no noticeable effect. He concludes that the Verdauungsarbeit may be likewise recognized with obese individuals.

The oxygen consumption after food was determined by Staehelin2 with the chamber method in 5 experiments on himself and 2 on tubercular patients. These experiments, made with the Jaquet respiration chamber in the Basel clinic, are of particular interest, since Staehelin attempted to minimize muscular activity and to secure uniformity in conditions by carrying out experiments in the night, when the subject slept for a greater part of the time. The importance of securing observations with the subject asleep and in complete muscular repose has recently been especially emphasized by many workers in metabolism. The experiments were somewhat complicated by the facts that the basal values were obtained but 6 or 7 hours after taking food rather than the customary 12 hours, and that in all the food experiments the metabolism had not reached the basal value 12 hours after the food was taken. Nevertheless, the results are of great significance in indicating the usual enormous increase in metabolism due to protein ingestion which, in one instance, corresponded to an increase of practically two-thirds of the caloric value of the protein ingested. In both the fat and carbohydrate experiments the increases were much larger than would commonly be expected, even though the caloric value of the material ingested was in both cases much greater than that of protein. In the observations on the tubercular patients Staehelin found similar increases. With one patient there was a very much greater increase after protein than with normal individuals, thus suggesting to Staehelin that the protein ingestion has a specific influence upon tubercular patients.

1Staehelin, Zeitschr. f. klin. Med., 1908, 65, p. 425.

2Ibid., 66, p. 201.