2 A BIOMETRIC STUDY OF BASAL METABOLISM IN MAN. 



uals which is apt to be overlooked by those whose experimentation has 

 been carried out on chickens, guinea pigs, or other animals or plants 

 on the one hand or in the clinic on the other. In the study of normal 

 metabolism the prejudices or suspicions of the subject must be over- 

 come and his convenience considered. This imposes a limitation upon 

 the number of measurements which can be fully realized by those only 

 who have had to meet these difficulties. Finally, the progress of the 

 work has shown the necessity for continuous refinement of method. 

 Thus it is quite impossible to use for present purposes the observations 

 of a few years ago. In the earlier work the necessity for complete 

 muscular repose on the part of the subject under investigation was not 

 fully enough realized. Individuals in the respiration chamber were 

 allowed to move about, telephone, write, or otherwise occupy them- 

 selves. More recent work has indicated that such apparently trivial 

 matters as the difference between the sitting and the reclining position 

 or such slight exertion as that required to raise the hand from the side 

 to the mouth may have a measurable influence on heat-production. 

 Furthermore, it has long been known that the presence of food in the 

 alimentary tract affects heat-production. The stimulatory action of 

 food has, therefore, to be taken into account. 



Thus the conditions under which the more truly basal metabolism 

 of the individual may be measured have been continually narrowed. 

 Of recent years students of human metabolism have reached a general 

 understanding concerning the conditions under which the heat- 

 production of an individual should be measured in order to obtain 

 values of the metabolism constant which shall be comparable from 

 individual to individual, and hence suitable as a standard basis of 

 departure for all studies of the influence of special conditions, whether 

 of sex, age, food, exercise or disease, upon the gaseous exchange. Deter- 

 minations made on the individual during complete muscular repose 

 and at a period 12 hours after the last meal, i.e., in the post-absorptive 

 condition, give what is commonly known as the basal metabolism. 

 Until very recently the number of measurements which fulfil the modern 

 high requirements was necessarily so small that it had not seemed worth 

 while to apply the modern methods of analysis to them. 



The development of series of measurements sufficiently large to 

 justify the use of the more refined statistical formulas in their analysis 

 has been in part due to a wider realization of the great practical as well 

 as the purely theoretical importance of a detailed and precise knowledge 

 of basal metabolism. The general public, as well as the handful of 

 nutritional specialists, is being forced these days by conditions of unpre- 

 cedented stress to a realization of the fact that an exact knowledge 

 of human nutrition is not merely fundamental in the clinic and useful 

 in home economics, but that it may even lie at the basis of national 

 survival. 



