INFLUENCE OF SEX ON METABOLISM. 185 



gives the total calories referred to age, that within the age limits of 

 approximately 10 to 12 years three points are specially designated to 

 show puberty, one very considerably above the general line and two 

 below. With two of these girls, puberty was well established, one at 

 10| years and the other at 12 years and 1 month, while with the third 

 child, at 12 years and 2 months, puberty was beginning. It was 

 possible to make observations with one of these girls (No. 239) at 

 11 years, before puberty began. At the earlier age (specially desig- 

 nated by inclosing the point in a diamond) the metabolism was 984 

 calories, while 1 year and 1 month later, after puberty was established, 

 it was 1,500 calories. Only in this one case is there apparent evidence 

 of a striking effect of puberty itself upon metabolism. An examination 

 of the rest of the curve shows no indication of a pronounced increase 

 in metabolism during the prepubescent age. 



The evidence with this one girl in figure 23 is, however, very decep- 

 tive, since on reference to figure 27, in which the total calories are 

 referred to weight, it is seen that in the year and one month inter- 

 vening between the two observations, this subject had gained in 

 \veight practically 12 kg. As a matter of fact, she had also increased 

 14 cm. in height. Accordingly, comparison may not be made directly 

 on the basis of total calories referred to age without taking into con- 

 sideration some of the physical factors. With the striking increase 

 in weight, the first obvious correction would be to consider the calories 

 per kilogram of body-weight with this subject at the two ages. This 

 has been done in figure 31, and here we note that the striking differ- 

 ences have practically disappeared, namely: at the age of 11 years, 

 the heat is 36 calories per kilogram of body-weight; at 12 years and 

 1 month, 38 calories. Precisely the same relationship holds true when 

 we compare calories per kilogram of body-weight at different weights, 

 as shown in figure 36. Consequently, a portion at least of the striking 

 difference in total metabolism noted with this child before and after 

 the establishment of puberty must be ascribed to the pronounced 

 alteration in body-weight. 



Having in mind the older conception of the significance of the body- 

 surface area, we should also consider the caloric output per square 

 meter of body-surface with this child. On reference to figure 47, 

 where the values are compared on this basis, we find that after the 

 age of 10 years there is a wide scatter of individual points. The one 

 girl at the age of lOf years with puberty established shows a value 

 considerably below the general line. Another at 12 years and 2 

 months, with puberty just beginning, is likewise slightly below the 

 line. The child with values before and after establishment of puberty 

 (No. 239) is represented at the later age, 12 years 1 month, when 

 puberty was fully established, by the highest point on the chart. The 

 heat production per square meter per 24 hours for this girl at 11 years 



