10 
PHYSIOLOGY: BENEDICT, HENDRY, BAKER Proc. N. A. S. 
In conclusion I desire to express my thanks to Professor R. A. Millikan 
for his kind advice and criticism. 
* A more detailed description of these experiments will later appear in the Physical 
Review. 
f National Research Fellow of the National Research Council. 
§ Such mobilities have been obtained below 100 mm pressures in air by all the ex- 
perimenters in this field up to the time of Wellisch. Until Thomson proposed his 
theory they had never been adequately explained. 
** This value depends on the correctness of the assumptions as to the numerical values 
of K' and L for the electron. 
1 Thomson, J. J., London Phil. Mag., Sept., 1915. 
2 Kovarik, A. F., Physic. Rev., Ithaca, 30, 1910 (415). 
3 Franck, J., Verh. deuts. physik. Ges., 12, 1910 (613). 
4 Loeb, L. B., These Proceedings, June, 1920. 
5 Loeb, L. B., Physic. Rev., 8, 1916 (6). 
6 Yen, K. L., Ibid., 9, 1918 (5). 
' Wellisch, E. M., Amer. J. Sci., New Haven, (Ser. 4) 44, 1917 (1); Phil. Mag., 34, 
July, 1917. 
THE BASAL METABOLISM OF GIRLS 12 TO 17 YEARS OF AGE 
By Francis G. Benedict, Mary F. Hendry and Marion L. Baker 
Nutrition Laboratory, Carnegie Institution of Washington, Boston 
Read before the Academy, November 17, 1920 
The Nutrition Laboratory's task of charting the field of basal metabo- 
lism of humans from birth to old age has resulted in a reasonable comple- 
tion of the study of boys and girls from birth to puberty, of both sexes, 
from the college age to 35 years, and of women about 50 years of age. 
The metabolism during the important age-range from 12 to 17 years, 
representing as it does a period of rapid growth as well as the period of 
the establishment of puberty, has recently been studied, so far as girls 
are concerned, in a large respiration chamber permitting the simultaneous 
measurement of the carbon-dioxide production of a dozen or more subjects. 
Groups of twelve Girl Scouts each volunteered as subjects, and a typical 
experiment involved their entering the respiration chamber after a light 
standard supper and sleeping quietly throughout the night. The entire 
carbon-dioxide production during the period of "bed rest," as well as the 
"minimum" carbon-dioxide production found throughout the night, are 
the bases for the computations of the energy needs for "bed rest" and for 
the basal metabolism. The quiet, resting morning pulse rate was obtained 
with all groups and the insensible perspiration was also measured with most 
of the groups. 
Special interest centres around the gaseous metabolism or, more par- 
ticularly, the energy computations therefrom. It was found that 55.0 
calories represented the average hourly heat production per individual, 
with very little difference due to either average age or average weight. 
