PREVIOUS INVESTIGATIONS. 25 



was collected in a bell-jar suspended over salt water. The carbon 

 dioxide was determined by titrating according to the method of Petten- 

 kofer; the oxygen was determined by explosion with hydrogen. With 

 himself, Marcet found that the oxygen consumed during digestion 

 was 21.37 grams per hour as compared with 20.26 grams during fasting. 

 The carbon-dioxide excretion also showed the influence of food. With 

 his assistant, even a greater increment in the oxygen consumption per 

 hour and per kilogram per hour was noted after food than with Marcet. 

 Marcet, 1892. Another set of experiments was made by Marcet 1 

 with a slightly modified apparatus which permitted the direct deter- 

 mination of the amount of the inspired air. One of the subjects was 

 Marcet himself, 64 years of age, and the other Smith, aged 23 years. 

 With Smith 6 fasting experiments 5 hours after breakfast and 14 food 

 experiments were made with environmental temperatures ranging 

 from 12.9 to 22.2 C. The average values obtained for a period of 8 

 to 9 minutes were as follows : With food the oxygen consumed was 280 

 c.c. and the carbon dioxide produced 229 c.c. ; during the fast the oxygen 

 consumed was 250 c.c. and the carbon dioxide produced 216 c.c. 

 Comparing the values obtained on himself and Russell in 1891 with these 

 values obtained on himself and Smith, Marcet draws the following 

 conclusions : 



"The influence of food on the interchange of respiratory gases, although 

 being attended with a rise in the oxygen consumed and carbonic acid expired, 

 apparently varies with reference to the oxygen absorbed. Young and strong 

 persons, requiring a full allowance of food, appear to absorb more oxygen 

 while under the influence of a meal than while fasting, but late in life the 

 oxygen absorbed appears to show little or no tendency to increase after a 

 meal." 2 



In 1895 Marcet maintained in a Croonian lecture that the "period 

 of the maximum consumption of oxygen is, undoubtedly, within the 

 first hour after a midday meal." 3 He concludes that with young men 

 there is distinctly more oxygen absorbed 2 hours after a full meal 

 than during a fast. In this discussion he used the results obtained 

 in his experiments in 1891 and 1892. 



Hanriot and Richet, 1891. In an extended series of observations on 

 a single subject, Hanriot and Richet, 4 employing essentially the same 

 apparatus as in their earlier researches, studied the influence of food and 

 fasting upon a subject 48 years old who weighed about 50 kilograms. 

 Two and three determinations per day were made for about 3^ months. 

 The average value for the carbon-dioxide excretion per kilogram and 

 per hour in 36 fasting experiments was 0.492 gram; in 86 experiments 



'Marcet, Proc. Roy. Soc., 1892-93, 52, p. 213. 



VbiW., p. 224. 



'Marcet, A contribution to the history of the respiration of man. Croonian Lectures delivered 



before the Royal College of Physicians in 1895, p. 28, 1897. 

 4 Hanriot and Richet, Ann. de Chim. et de Phys., 1891, ser. 6, 22, p. 495. 



