24 FOOD INGBSTION AND ENERGY TRANSFORMATIONS. 



Experiments were made with the subject fasting, with 500 grams of 

 roast beef twice per day, with a large amount of potatoes, with glucose, 

 and with fat (lard) and egg yolks. They conclude from this series of 

 experiments that protein and fat modify the respiratory exchange but 

 very little; starchy foods increase the lung ventilation and the absorp- 

 tion of oxygen, and especially the production of carbon dioxide. Their 

 results show that with man during fasting there is a production per 

 kilogram per hour of 0.5 gram of carbon dioxide and an absorption of 

 0.45 gram of oxygen, and that during digestion the production of carbon 

 dioxide increases to 0.6 gram and the oxygen absorption to 0.50 gram, 

 an increment of approximately 10 per cent. 



Loewy, 1S88. In a series of experiments made by Loewy 1 in Zuntz's 

 laboratory and primarily designed to study the influence of unoxi- 

 dizable material (Glauber salts) in the intestinal tract, two experiments 

 were made with water. In one it was found that 11 minutes after the 

 subject had taken 100 grams of water the oxygen consumption in- 

 creased from 218.5 c.c. to 221.8 c.c. per minute, an immaterial increase. 

 Later (33 minutes after drinking the water) the oxygen consumption 

 had increased to 232.2 c.c. i. e., an increment of 14 c.c. of oxygen, 

 or approximately 6 per cent. In another experiment, 10 minutes 

 after taking 100 grams of water, the oxygen consumption increased 

 from a basal value of 221 c.c. per minute to 226 c.c. per minute, an 

 increment of only 5 c.c. of oxygen. Approximately half an hour later 

 the oxygen consumption had increased to 242 c.c. per minute. Since 

 no graphic record of the activity accompanied these experiments- 

 an omission which has been criticized 2 it is difficult to state with 

 certainty whether or not the ingestion of water actually produced a 

 measurable increase in the metabolism. 



Marcel, 1889. Marcet 3 reported the results of a series of experiments 

 with two subjects, which were designed primarily for a study of the 

 influence of food. The general conclusions confirm the results of 

 previous observations on the influence of food upon the carbon-dioxide 

 production, namely, that the maximum amount occurs between 2 and 

 3 hours after the meal and the minimum amount just before breakfast. 



Marcet, 1891. Later, Marcet 4 published the results of a series of 

 experiments on himself and his assistant, Russell, in which 6 experi- 

 ments were made on each subject, about 2 hours after food, and 6 

 experiments during "fast," i. e., 4 hours after breakfast. Each experi- 

 ment lasted 7 to 8 minutes. The subject, reclining in a steamer chair, 

 inhaled through the nose and exhaled through the mouth, sometimes 

 closing the nostrils with the fingers when necessary. The expired air 



'Loewy, Arch. f. d. ges. Physiol., 1888, 43, p. 515. 



^Benedict and Emmes, Am. Journ. Physiol., 1912, 30, p. 197. 



:( Marcet, Proc. Roy. Soc., 1889, 46, p. 340; also, Phil. Trans., 1890, 181, ser. B, p. 1. 



*]}>;<!., 1S91 92, 50, p. 58. 



