24 PHYSIOLOGY OF THE NEW-BORN INFANT. 



in these experiments is shown to bring about a decrease in the oxygen 

 intake, and a consequent increase in the respiratory quotient, only 

 when the oxygen percentage in the atmosphere is at the same time 

 very low (i. e., 8 per cent against 20 per cent in my experiments) . This 

 fact is strikingly demonstrated by a comparison of 12 and 2 in table 1 

 (with the same percentage of carbon dioxide and extreme difference 

 between quotients) and a comparison of 13 in table 2 and 5 in table 3 

 (with an extreme difference between the percentage of carbon dioxide 

 and approximately the same quotient). 



As regards the amount of the metabolism in the above experiments it 

 seems impossible for me to conclude anything else from the tables than 

 that the activity of the infant is the chief determining factor, and that 

 the influence of other conditions, such as the condition of nourishment, 

 age, etc., is not demonstrated, at least by my method of experimenta- 

 tion. The influence of activity is overwhelming and is observed 

 regularly in the double experiments in table 2, and 10 and 11 in table 3, 

 in which the child in the second experiment is always either drowsy or 

 asleep. In the single experiments, also, we find a striking parallelism 

 between the amount of the metabolism recorded and the intensity of 

 the activity. It is naturally quite difficult to judge of and to express 

 in words the degree of strength with which the infant has contracted 

 its muscles in the course of 23 minutes. In the experimental pairs 17- 

 18 and 19-20 (table 2) I have repeatedly awakened the infants in the 

 second experiment by rapping loudly on the cover of the respiration 

 chamber. The purpose was to keep the activity and thereby the 

 metabolism artificially at the same level as in the first experiment. 

 Although the infants reacted to every rap with severe general contrac- 

 tion of the muscles, the drowsiness throughout the entire period has 

 been the determining factor; the metabolism in experiments 19 and 20 

 fell 25 per cent. 



Even though it is difficult to determine the work which the different 

 children have done during the experiment and therefore difficult to 

 arrive at a numerical expression for the effect of work on the amount 

 of the metabolism, it is easy to convince one's self of the absolute 

 absence of visible contractions. When such a condition has prevailed 

 throughout the 23 minutes of the experiment we find a very low metabo- 

 lism value from 270 to 300 c.c. carbon dioxide per kilogram and per 

 hour. Such figures are found both for infants overweight (3,950 grams in 

 experiment 8 of table 1, etc.} and for infants underweight (1,825 grams in 

 experiment 5 of table 3, etc.}. After due reflection this is not surprising. 

 The heat regulation of a new-born infant 1 is very poorly developed. 

 Even if it were not poorly developed, the temperature during the 

 experiment is so regulated that the question of the feeble heat regula- 

 tion of the child is eliminated as far as possible. Thus every experi- 

 mental condition which would produce a smaller metabolism per unit 

 of weight in the large infant with a relatively small surface than in 

 the smaller infant with a relatively large surface is eliminated. But 

 there is cause for reflection in the fact that a figure like 270 c.c. for the 



'Babdk, Archiv f. d. ges. Physiol., 1902, 89, p. 154. 



