2 METABOLISM AND GROWTH FROM BIRTH TO PUBERTY. 



many a few minutes after their birth, and all during the first week of 

 life. 1 An earlier report of a study of infants has also been published, 

 with the primary object of indicating methods of study and certain 

 physiological correlations, particularly pulse-rate and metabolism. 2 

 At the time of this earlier report, the number of normal individuals 

 obtainable was relatively few and a somewhat large number of atrophic 

 infants, with a few pathological cases, were included to show what 

 might be expected for variation in metabolism in the hospital ward. 

 With the completion of the study of new-born infants, the next step 

 was the study of the basal metabolism of children at various ages from 

 one week to puberty. The results of this latest investigation we pur- 

 pose presenting in this report. 



BASAL METABOLISM. 



Basal metabolism may be considered as the sum total of all the 

 vital activities of the quiet organism in the post-absorptive condition, 

 i. e., the minimum or maintenance metabolism unaffected by extrane- 

 ous factors. This may be expressed in terms of heat produced or of 

 gaseous exchange incidental to heat production (carbon-dioxide pro- 

 duction and oxygen consumption). Using this basal metabolism as a 

 standard, we may then measure definitely the effect of superimposed 

 factors. 



In these studies of the basal metabolism from birth to puberty, it 

 has been our aim to determine the metabolism at the different ages 

 under identical conditions as far as possible, so that the results may 

 be entirely comparable. To obtain comparable results with indi- 

 viduals of varying ages, certain experimental conditions should exist. 

 In the first place, in view of the pronounced influence of muscular 

 activity upon basal metabolism, it is desirable that all subjects should 

 have the same degree of muscular repose. An ideal condition would 

 be complete muscular repose. The difficulty of securing such repose 

 with young children is obvious, for infants of one or two years of age 

 differ widely in muscular movements and temperament from an 

 adolescent boy or girl. With adults and older children the muscular 

 activity may be voluntarily so controlled that the increase in meta- 

 bolism due to activity, even in restless periods, will be but 15 to 20 per 

 cent. With crying children, with whom the activity is involuntary, 

 the increment was found in our earlier studies to be at times over 200 

 per cent and on an average 65 per cent. 3 



Second, it may be stated that, theoretically at least, the ingestion 

 of any energy-producing food-material increases the metabolism by 



1 Benedict and Talbot, Carnegie Inst. Wash. Pub. No. 233, 1915. 



2 Benedict and Talbot, Carnegie Inst. Wash. Pub. No. 201, 1914. For a briefer report, see 



Benedict and Talbot, Am. Journ. Diseases of Children, 1914, 8, p. 1. 



3 Benedict and Talbot, Carnegie Inst. Wash. Pub. No. 233, 1915, p. 112, table 17. 



