Zuntz And Magnus-Levy, 1891

In studying the digestibility and nutritive value of bread, Zuntz and Magnus-Levy,1 employing a Zuntz-Geppert respiration apparatus, made a number of experiments on themselves, not only in the post-absorptive condition but likewise after 250 to 300 grams of bread and 60 grams of butter. Although recognizing the fact that their data need amplification, they tentatively conclude that bread causes a fairly considerable increase in the oxygen consumption, the increase in the first hour amounting to about 25 per cent of the fasting value. Subsequently the oxygen consumption decreases and at the end of 3 to 5 hours reaches practically the basal value. They further conclude that, in general, the increase above the fasting value is, with bread, about 15 per cent during the first 6 hours, but that on the 24-hour basis the increase due to digestion would be not less than 10 per cent of the total oxygen consumed during rest. Frequently, in reporting an increase due to metabolism, writers confuse an increase obtained for a short time, i. e., a "peak" increase, with that obtained in a 24-hour period. Apparently Zuntz and Magnus-Levy were the first to make a sharp distinction between these increases. This practice could well be followed by modern writers.

Hanriot, 1892

The interesting series of observations on the effect of taking glucose, reported by Hanriot in 1892,2 are of greater significance as regards the influence upon the respiratory quotient than as to the effect upon the total metabolism. Hanriot's paper emphasizes the fact that the respiratory quotient may attain a value as high as 1.30. Under these conditions there is a transformation of carbohydrate into fat, and the values do not lend themselves easily to a computation of the increased metabolism due to the digestion of the glucose, for apparently the oxygen values determined by Hanriot are given with some reserve.

In Hanriot's article published in 1893,3 which is a continuation of his first paper published in 1892, emphasis is laid primarily on the respiratory quotient and on the transformation of carbohydrates into fat. Of special interest in view of our own contrary findings is Hanriot's statement that with 50 grams of glucose dissolved in 500 c.c. of water the quotient always rises to about 1.25. The paper concludes with an extensive discussion of the theoretical points involved in the transformation of carbohydrate into fat.

1Zuntz and Magnus-Levy, Arch. f. d. ges. Physiol., 1891, 49, p. 438. 2Hanriot, Compt. rend., 1892, 114, p. 371. 3Hanriot, Arch, de Physiol., 1893, 25, p. 248.

Likhatscheff, 1893

Likhatscheff,1 describing the Pashutin respiration calorimeter for man, cites the results of three food experiments and one fasting experiment, the latter being made for the specific purpose of providing a basal value for the study of the influence upon metabolism of taking food. Since this represents the first experiments on man in which direct calorimetry was applied, and direct measurements of carbon-dioxide production and indirect measurements of oxygen consumption were made simultaneously, the results are given in table 4.

Table 4. - Metabolism In Food And Fasting Experiments (Likhatscheff)

Here it is seen that on at least 2 of the 3 days with food the oxygen consumption was materially higher than that on the fasting day. The author finds that the curves for heat production and gaseous exchange reach their highest point during the day and their lowest point at night. Since both of these factors are complicated by the small incidental muscular movements during the day, the diurnal variations can not be ascribed to digestive processes alone.

D'Arsonval, 1894

In reporting the tests of his anemo-calorimeter, d'Arsonval2 gives the results of an experiment on himself (weight 74 kilograms, age 42 years), in which the heat output per hour, when he was standing dressed and fasting, was 79.2 calories. One hour after breakfast (the kind and amount of food not given) the metabolism under the same conditions of standing with clothing rose to 91.2 calories, an increment of approximately 18 per cent.