TECHNIQUE FOR METABOLISM DURING REST. 



83 



oxygen consumed by means of a direct reading of the level of the 

 spirometer bell at the beginning and end of an experiment. 



After leaving the air-purifying bottles, the air passes through a tube 

 to the mouth of the subject. The expired air, containing carbon diox- 

 ide, is drawn through a large-caliber tube to the spirometer, from which 



(■ ■~«^52^ 



-Connections with subject, portable 

 respiration apparatus. 



E, second water absorber; W, pipe carrying air 

 to subject; G, pipe conducting expired air 

 from subject to spirometer; V, 3-way valve 

 between air-circuit and mouthpiece; A, hand 

 wheel controlling adjustment of 3-way valve 

 and mouthpiece on extension arm, L; B, 

 hand^ wheel permitting the raising or lowering 

 of L on standard, S. The portable nature of 

 the apparatus is indicated by the mounting 

 of base on castors. 



it is whirled by the blower through the purifying bottles, and thence 

 returned to the subject for rebreathing. The connections with the 

 subject are shown in figure 2 and the general installation and details of 

 the air-circuit in figure 3. 



ROTARY AIR-IMPELLER. 



The portable respiration apparatus is a recent development of the 

 universal respiration apparatus,^ but has many striking similarities to 

 the early ''oxygenographe" of Fredericq^ and the later device of 

 Krogh.^ In at least one main particular, however, this apparatus 

 differs from the earlier forms in that the air is circulated not by the 

 lungs of the subject, but by an electrically-driven fan. There are no 

 valves to be actuated by the lungs, and the fan does all the work of 



1 Benedict, Deutsch. Arch. f. klin. Med., 1912, 107, p. 156; see also Am. Journ. Physiol., 1909, 



24, p. 345. 

 * Fredericq, Arch, de Biol., 1882, 3, p. 687; also Elements de Physiologie Humaine, Ghent and 



Paris, 1888, 2d ed., p. 141. 

 « Krogh, Skand. Arch. f. Physiol., 1913, 30, p. 379. 



