24-HOUR ENERGY REQUIREMENTS. 207 



the kymograph, to which we have arbitrarily assigned values of I to VI, 

 the statistics of these periods of activity can have little quantitative 

 value to other observers, and accordingly they are not published here. 

 All of the results for these periods have been gathered together, how- 

 ever, and certain deductions seem justified by an inspection of the 

 data. In the first place, the very great increases noted with new-born 

 children may occasionally be obtained with children up to the age of 

 9 months, but the average of 65 per cent found with new-born babies 

 does not continue after the first few weeks of life. Subsequently, 

 until the age of 6 months, the average increase due to activity may be as 

 high as 40 per cent. As the age of the child increases and voluntary 

 muscular control becomes more possible, the increments noted by us 

 decrease in value, until after 7 years of age an increase due to activity 

 of over 30 per cent of the basal value is rarely found. This obtains 

 for girls as well as for boys. 



Two important points stand out as a result of this inspection of data : 

 First, that the younger the infant the greater is the percentage increase 

 in metabolism during lying on account of crying and active movement 

 of the body, arms, and legs; and second, that with the older children 

 voluntary control has so increased as greatly to reduce the maximum 

 activity. 



These values have special significance in that they throw light upon 

 the practical use of the basal value in the computation of the total 

 24-hour requirement of the child. From the fact that in our experi- 

 ments children after 7 years of age rarely had a heat production more 

 than 30 per cent above the basal in periods of restlessness or activity, 

 we feel justified in concluding that the basal value is almost synony- 

 mous with the heat production of children over 7 years of age while 

 in bed, save for the stimulating effect of food. Since children are for 

 the most part anywhere from 8 to 12 hours of the day in bed, this 

 forms an important quota of the total 24-hour requirement. 



Further than this with the older children we may not go. The great 

 differences in muscular activity of the boy or girl at play, differences 

 which are fully attested by recent studies of the food consumption in 

 boys' schools, 1 shows that the actual caloric output during the waking 

 period and when the children are actively at play is very much greater 

 than the basal output, i. e., that obtained when the child is in bed 

 resting quietly. 



With babies, whose time for the most part is spent in bed, some- 

 what more definite information is at hand, as two 24-hour experiments 

 have been made which have already been reported. 2 With one 

 infant, E. L., 2 months and 3 weeks old, and having a body- weight 

 at the time of observation of 5.03 kg., the basal heat-output per 24 



1 Gephart, Boston Med. and Surg. Journ., 1917, 176, p. 17. 

 * Talbot, Am. Journ. Diseases of Children, 1917, 14, p. 25. 



