84 METABOLISM AND GROWTH FROM BIRTH TO PUBERTY. 



61.26 for men. 1 These differences are substantiated by the fact that 

 with men three different groups of 28, 116, and 50 men showed average 

 pulse-rates of 62.5, 61.3, and 61.3, respectively. Two groups of women, 

 one of 68 and the other of 22, showed pulse-rates of 69.1 and 67.3, 

 respectively. In other words, it seems thoroughly established that 

 the women as a class have a pulse-rate somewhat higher than men, in 

 spite of the fact that their metabolism is distinctly lower. This sup- 

 plies very clear evidence that while pulse-rate and heat production 

 may be closely correlated in the same individual, in groups of indi- 

 viduals the pulse-rate may vary enormously and "average" pulse-rate 

 may have little, if any, connection with "average" heat production. 



Since the pulse-rates of men and women show a difference, it becomes 

 extremely important, in studying our groups of children, to note at 

 what point, if any, there is a definite change in the pulse-rate, and 

 further comparisons of values for males and females will be of special 

 interest in this connection. Such comparison may be made from the 

 pulse-rate data for boys and girls in table 20, which gives an oppor- 

 tunity of noting the differentiation, if any, due to sex. To this end, 

 wherever values for both boys and girls are recorded at the same age, 

 the higher of the two values has been italicized. Thus, for children 

 1 day old, 29 boys gave an average minimum pulse-rate of 113, while 

 21 girls had a pulse-rate of 110. On the next day the conditions for 

 very nearly the same number of boys as girls were reversed, the girls 

 showing a pulse-rate 4 beats higher than the boys. 



Pursuing this method of analysis for the entire group of data in 

 table 20, and passing over those ages for which records are available 

 for only one of the two sexes, we find that at 11 age-periods the boys 

 have a higher pulse-rate than the girls of the same age, while at 15 

 age-periods the girls have a higher pulse-rate than boys of like age. 

 On this basis, therefore, it would appear that the pulse-rate of the 

 girls was, on the whole, somewhat higher than that of boys. The 

 italicized figures in the table show no great regularity in the appear- 

 ance of these high values with either sex. The most consistent record 

 is that from 1^ months to 10 months, the only ages at which the girls 

 are not higher being that of 4 months, and again of 5 months, when the 

 average pulse-rate for both sexes is the same. After 10 months the 

 italicized figures indicate but little regularity as to sex. 



On the whole, the picture can not be said to speak pronouncedly for 

 a higher pulse-rate with girls than with boys. In making this general 

 conclusion, however, it is important to note that the data under con- 

 sideration are at best somewhat meager, although they may be relied 

 upon as far as they go. But many observations of the minimum 

 resting pulse-rate of boys and girls are necessary before final conclusions 



1 Harris and Benedict, Carnegie Inst. Wash. Pub. No. 279, 1919, p. 66. 



