226 A BIOMETRIC STUDY OF BASAL METABOLISM IN MAN. 



exactly with a generally adopted set of conditions that there is no 

 advantage in carrying out a normal control determination coincident- 

 ally with the measurement of the metabolism of subjects suffering 

 from any disease which may be under investigation. 



The necessity for establishing a standard control series rests upon 

 two fundamental considerations. First, variation in basal metabolism 

 from subject to subject is so great that to be of critical value a control 

 series must comprise a relatively large number of individuals. Sec- 

 ondly, the very limited equipment available in all the scientific insti- 

 tutions of the world for carrying out trustworthy metabolism deter- 

 minations and the great expenditure in time and effort necessary for 

 making these determinations render it practically essential that data 

 which may be regarded as standard for long periods of time be secured 

 once for all, in order (in so far as possible) to set the limited equipment 

 free for investigating the many pressing problems of metabolism under 

 special conditions of exercise, nutrition, and disease. Hitherto control 

 values have been established in two ways. 



First, the average value of metabolism per unit of body-weight or 

 body-surface in a selected group of subjects has been used as a control 

 value, and the observed metabolism of the hospital patient or other 

 subject, expressed in terms of the same units, has been compared 

 directly with this value. This is the method used by the majority of 

 investigators in the past. 



Second, the average of the constants secured from a group of normal 

 individuals as nearly as possible comparable, in physical characters, 

 with the subjects of the special group under consideration is used as a 

 standard of comparison. This is the selected-group method employed 

 at the Nutrition Laboratory in a study of diabetes, of vegetarians and 

 non-vegetarians, of athletes and non-athletes, and of men and women. 



The obvious objection to the population-average method of com- 

 puting control values is that, in obtaining the fundamental constant, 

 individuals of the most diverse physical characters are lumped together 

 indiscriminately. From the physiological standpoint it is quite unrea- 

 sonable to compare a standard value obtained from a large number of 

 normal robust individuals with that derived from an emaciated patient 

 in the clinic ; this is evidenced by the fact that an individual undergoing 

 a prolonged fast may show a decrease of 28 per cent in his metabolism, 

 as measured in relation to body-surface, simultaneously with the 

 assumption of an emaciated condition quite comparable with that 

 observed in some pathological subjects. 



The selected-group method in which pathological or other special 

 groups are compared with normal individuals of like height and weight, 

 i.e., of general anatomical and morphological similarity, is free from 

 this very serious criticism, but is open to two others. (1) There is 

 considerable opportunity for personal equation in the selection of the 



