Speck, 1873

The possibility for change in the character of the metabolism after the ingestion of food of varying chemical composition, with consequent changes in the carbon-dioxide excretion not at all commensurate with the true changes in energy transformation, led Speck to make an extensive series of observations upon the respiratory exchange in man, in which we find the first basic determinations of oxygen consumption. By analyzing the expired air, which was collected in a spirometer, Speck was able to determine the carbon-dioxide increment and the oxygen deficit in the air passing through the lungs. From these values he computed the carbon-dioxide production and the oxygen consumption per minute. These varied considerably with different conditions of body activity and after the ingestion of food. Speck's several papers appeared between 1865 and 1892, but were brought together and summarized by him in one publication.1 In his earliest communication on the influence of food ingestion2 he observed that the respiratory exchange was increased about 12 per cent by an ordinary mixed diet. In another series, published by him in 1874,3 he reports numerous experiments with food and concludes that the respiratory exchange is increased after the noon meal 25 per cent. This marked increase in heat production, which takes place, he finds, within 30 minutes after a meal, led him to the belief that the work of digestion must cause this increased gaseous metabolism, since it is not to be expected that much food would be absorbed into the blood within the short space of 30 minutes. From the protein experiments4 he concludes that 2 hours after the meal the height of digestion is passed and that at the end of 4 hours digestion is completed. In the sugar experiments he finds that 1 hour after the ingestion of sugar the digestion ceases. In two experiments with coffee he records a small but visible rise in the metabolism. Two experiments were made likewise on the effect of water-drinking and of flooding the body with water for some time before the experiment. According to his results, when the water is taken the evening before and to within an hour of the experiment in the morning there is no influence upon the metabolism; when the water is taken a short time before the experiment, that is, 1,250 c.c. in an hour, and the experiment is made about 30 minutes after the completion of the water-drinking, he notes a marked rise in the gaseous metabolism.

Fredericq, 1882

By using a most ingenious apparatus, called by him an "oxygenographe," Fredericq,5 in the laboratory at Liege, was able to determine the oxygen consumption directly on man both before and after taking food. This apparatus is a modification of an earlier form devised for animals. It is of special interest in that the oxygen is supplied to the apparatus by means of a movable bell floating in a bath of chloride of calcium solution, a principle which underlies the present universal respiration apparatus so extensively used in this and other laboratories. The carbon dioxide is absorbed by a mixture of lime and caustic soda, but the oxygen consumption is the only factor measured. Fredericq concludes that digestion is accompanied by a marked increase in the consumption of oxygen and illustrates this by several interesting curves of oxygen consumption throughout the day which show the relationship of this factor to the time in which food was taken. In a typical experiment he finds the oxygen consumption can increase from 4.5 liters in 15 minutes (fasting) to a maximum of 6.12 liters after a meal. He lays special emphasis upon glandular activity in the work of digestion, which he thinks accounts for this increase in oxygen consumption. His results agree for the most part with those of current observations, except for showing an extraordinarily rapid return to the basal level following food. Fredericq's conclusions regarding digestion represent a very great advance and deserve to be widely quoted at the present time. His article gives one of the best considerations of digestive activity ever written.

1Speck, Physiologie des menschlichen Athmens, 1892.

2Speck, Tagebl. d. 46 Vers. d. Naturf. u. Aerzte in Wiesbaden, 1873, p. 136.

3Speck, Arch. f. exp. Path. u. Pharm., 1874, 2, p. 405.

4Speck, Physiologie des menschlichen Athmens. 1892.

5Fredericq, Arch, de Biol., 1882, 3, p. 687; Elements de Physiologie Humaine, 2d ed., 1888.

Henrijean, 1883

Henrijean,1 publishing from Fredericq's laboratory, and using his apparatus, made a study of the influence of alcohol in nutrition. The experiments were made each morning at the same hour and continued 15 minutes; 5 were fasting experiments, 4 after alcohol, and 3 after food. In the food experiments bread varying in amount from 120 to 190 grams was given. The results are expressed as oxygen consumed in 15 minutes, reduced to standard conditions of temperature and pressure. Thus during fast the oxygen consumption was 3.5 liters, with alcohol 4.17 liters, and with bread 4.35 liters. From these data Henrijean concludes that the amount of oxygen consumed after alcohol or food in general is always greater than that when fasting; the increment after bread is approximately 25 per cent; after alcohol it is a little less.

Jolyet, Bergonie, And Sigalas, 1887

Using a new respiration apparatus on a closed-circuit plan, in which the subject breathes through a hermetically sealed mask, Jolyet, Bergonie, and Sigalas2 report two series of experiments which have a slight bearing upon the question of the influence of food. Thus, as an average of 7 experiments with the subject fasting and at rest, they found the oxygen consumption per kilogram per hour was 259 c.c. In 7 experiments with food (neither the kinds nor the amounts of food are stated) the oxygen consumption was 275 c.c. per kilogram per hour. Apparently no further experiments were made on this problem with the apparatus.