82 VITALITY AND EFFICIENCY WITH RESTRICTED DIET. 



uniformity. It is of interest to note that subsequently the coopera- 

 tion of the subjects was so perfect, the technical skill of the operators 

 so satisfactory, that duphcate analyses were rarely called for. Thus, 

 the daily gas analyses (aside from the daily outdoor air control) could 

 usually be completed after 4 analyses with 2 subjects and 6 analyses 

 with 3 subjects. 



The special care given to these measurements of the gaseous metab- 

 oUsm was fully justified by the unusual significance of the results. 

 This procedure supplied us with the most exact picture of the transition 

 in basal metabolism of the individual subjects from day to day as the 

 reduced diet continued. It is the clearest picture of variations in the 

 individual basal metabolism and likewise of the absolute values for the 

 metabolism that we have throughout the whole study. 



PORTABLE RESPIRATION APPARATUS. 



The complexity, nicety of manipulation, and care required for metabo- 

 lism measurements by means of a mask, valves, spirometer, and gas 

 analysis, precluded the use of this method for more than two or at best 

 three of the 12 subjects each day. On the other hand, it was agreed that 

 changes of considerable importance might take place inside of a week 

 which should be noted, if possible. Hence we employed a new type of 

 respiration apparatus, which had been primarily developed for clinical 

 work, but not extensively used in the Laboratory prior to this research.^ 

 By means of seven of these apparatus, specially constructed for the 

 purpose, the measurements were extended each morning so that two 

 observations were made with the respiratory- valve type of apparatus 

 and seven with the new portable type. We thus obtained basal 

 measurements for 9 of the 12 men daily. 



GENERAL PRINCIPLE OF APPARATUS. 



In the portable respiration apparatus, the subject breathes into and 

 out of a confined volume of air that circulates through a series of 

 purifiers which remove the carbon dioxide as fast as formed. As the 

 air passes through the lungs of the subject, oxygen is absorbed from 

 the air, with a consequent gradual decrease in the oxygen content. 

 The decrease in the total volume of the air represents the volume of 

 oxygen consumed. 



The portable respiration apparatus consists of a mechanical blower 

 to circulate the air, three bottles which contain purifying material to 

 remove the carbon dioxide and water-vapor, and a spirometer with 

 suitable piping and connections. The spirometer serves the triple 

 purpose of providing (1) a suitable housing for the mechanical blower; 

 (2) a fluctuating factor in the air-circuit to allow for inspiration and 

 expiration, i. e., an expansion chamber; and (3) a measure of the 



1 Benedict, Boston Med. and Surg. Jonrn., 1918, 178, p. 667. The description, together with 

 figiires, is in large part reprinted from this article. 



