PART I. 



INTRODUCTION. 



Observations on the metabolism of infants have for the most part 

 been confined to records of food intake, changes in body-weight, and 

 analyses of urine and feces. Studies of the gross metabolism of the 

 body, necessitating either direct calorimetric observations or meas- 

 urements of the gaseous exchange, demand elaborate apparatus and 

 unusual technique and hence they have been precluded in most clinics 

 and laboratories. Before entering into a discussion of our researches 

 in this field, it is desirable to cite briefly the evidence on the gaseous 

 exchange of infants thus far published. 



The earliest record that we have been able to find of the measurement 

 of the gaseous metabolism of an infant is that reported by J. Forster, of 

 Munich, in 1877. 1 In an effort to explain the well-known fact that 

 children consume a larger amount of food in proportion to their body- 

 weight than do adults, this investigator made determinations of the 

 carbon-dioxide excretion in 14 experiments on children varying in age 

 from 14 days to 9 years. His results all showed that 10 or 12 grams 

 of carbon dioxide were given off per hour for every 10 kilograms of 

 body-weight. With adults on the same basis, the carbon dioxide given 

 off under conditions of rest and approximate hunger was 4 to 5 grams 

 per hour; with an average diet, 5 to 6 grams; and with food and work, 

 7 grams. The author points out that the youthful organism, even in 

 the condition of hunger, produces per unit of weight at least twice the 

 amount of carbon dioxide which is produced by the adult body. The 

 fact is also recognized that the infant can develop a considerable amount 

 of work, as will be seen by the following quotation: 



"Bedenkt man noch die relativ grossen Arbeitsleistungen, welche die meist 

 lebhaften kindlichen Korper ausfuhren, so ergibt sich, dass erne relative Mehr- 

 zufuhr von Speisen fur den kindlichen Organismus eine durch innere Verhalt- 

 nisse bedingte Nothwendigkeit ist." 



The experiments were made with the large Pettenkofer-Voit respi- 

 ration chamber in Munich, but the protocols were never published, and 

 aside from the statement that the children were at rest, no further 

 details are given as to the muscular activity or the pulse-rate. 



In 1885 Richet, 2 in describing his calorimeter, states that he has two 

 chambers, one of which, having a capacity of about 1,500 liters of air, 

 is used for experiments with infants. He cites an experiment with an 

 infant of 9 kilograms, who was in the chamber for 1 hour and 10 minutes, 



iForster, Amtl. Ber. d. 50. Versammlung deutsch. Naturforscher u. Aerzte in Munchen, 

 Munich, 1877, p. 355. 



2 Richet, Archives de Physiol, norm, et path., 1885, 15, 3d ser., p. 237. 



