538 



JOHN R. MURLIN 



minute; but Krogh has shown that experiments of even much shorter 

 duration are sufficient to give perfectly reliable results. 



The method of Zuntz and Geppert of measuring the expired air as it is 

 exhaled and collecting at the same time a continuous aliquot sample for 

 analysis is an important one and has been very widely used in Europe. 

 The subject breathes through a mouth-piece attached to a tee-tube connect- 



Fig. 17. Respiration apparatus of Douglas. The mouth-piece is of the Denay- 

 rouse type. The bag or bellows is provided with straps for carrying the apparatus 

 on the back. 



ing two valves (made of rubber and glass as used in the Zuntz laboratory, 

 Magnus-Levy (&)) which separates inspired from expired air. The latter 

 passes at once through a moist gas-meter. The continuous sample is taken 

 over water by an automatic apparatus and is then immediately analyzed in 

 a special analyzer in which the CO 2 is absorbed by potash and the oxygen 

 by phosphorus. In the figure (Fig. 18) the meter is shown at the left and 

 the special air analyzer is shown at the right. The expired air enters the 

 apparatus at P. The sample is drawn through the narrow tube, L, by the 

 lowering of the water-tube, H, which descends at a rate proportional to the 

 ventilation as measured by the meter. As the tube, H, descends water 



