78 METABOLISM AND GROWTH FROM BIRTH TO PUBERTY. 

 INFLUENCE OF AGE UPON THE PULSE-RATE. 



The pulse-rate at the end of fetal life is said to average between 135 

 and 140 per minute, but it is only with extra-uterine pulse-rate that 

 our observations deal. In the study of new-born infants we were 

 able in no case to make observations of the pulse-rate of the same 

 child throughout the entire first week. The average pulse-rates for 

 the first seven or eight days of life given in the report of that study 

 must consequently be looked upon as showing only the general trend 

 of the average pulse-rates of new-born children. 



In our first report we tabulated all of the available data for the 

 pulse-rate for each of the first 8 days after birth, regardless of whether 

 the measurement of the metabolism during these periods gave strictly 

 minimum results or not. 1 Our conclusions were based upon these 

 pulse data, but it was definitely stated that the values for the pulse- 

 rate were those of infants during periods of approximately minimum 

 heat production and that the metabolism during these periods could 

 be considered as absolutely minimum in only a relatively few cases. 

 In this publication it seems best to present the data for the pulse-rate 

 of new-born infants for comparison purposes, using as a basis of 

 selection, however, the periods in which the minimum heat production 

 was obtained. The pulse-rates for these periods of minimum heat 

 production are given in table 16. A comparison of the figures for 



TABLE 16. Pulse-rate during first 8 days after birth. 



pulse-rate given in the earlier report 2 with those in table 16 shows that 

 this later method of selection lowered the daily averages on all but 

 the first and fourth days, there being no change on these days; that 

 is, when the effort is made to tabulate only pulse-rates with minimum 

 heat production, in most cases this approximation to the minimum heat 

 production is accompanied by a distinct reduction in the average pulse- 

 rate. Since all of the subsequent material on pulse-rate in this report 

 is based upon the values found during minimum muscular activity, 

 for the final summation of pulse-rate values for children the averages 

 given in table 16 will be used rather than those in the earlier report. 



1 Benedict and Talbot, Carnegie Inst. Wash. Pub. No. 233, 1915, table 19, p. 115. 

 'Benedict and Talbot, Carnegie Inst. Wash. Pub. No. 233, 1915. p. 116. 



