120 EXPERIMENTAL PHYSIOLOGY. 



In conducting the observation, the spirometer is first set at zero 

 on the scale at the side. The subject then breathes for some time 

 through the valves and a side tube with the stopcock turned off. 

 When the breathing is comfortable, the stopcock is turned so that 

 the air enters the spirometer, and the side tube is closed by placing 

 a clamp on the rubber tubing on its free end, the exact moment 

 being noted. The air is allowed to collect for a definite period of 

 time (4 to 5 minutes for a subject at rest), at the end of which the 

 stopcock is again turned and the side tube opened so as to connect 

 with the outside. The temperature in the spirometer and the 

 barometric pressure are then carefully noted, as well as the volume 

 of air in the spirometer. The number of respirations during the 

 observation is also counted. 



The sample of air for analysis is collected in an all-glass syringe, 

 the nozzle of which fits into the rubber tubing of the stopcock on 

 the top of the cylinder. To allow for the dead space of the tubing, 

 the syringe,. after filling, is removed from the tubing (after turning 

 off the tap again), emptied and reconnected. The piston is then 

 moved out and in several times, and the syringe, filled with air, is 

 removed to the gas analysis burette and the analysis made according 

 to the directions in Exp. 49. 



It is particularly important to make certain that all the oxygen 

 is absorbed by the pyrogallate and that the air entrapped in the 

 tubing leading to the CCVabsorption pipette is included in the 

 analysis. 



THE CALCULATIONS. The following have to be determined: 



1. Per cent CO 2 and O 2 . 



2. Respiratory Quotient. 



3. Total vol. CO 2 and O 2 respired per kgm. body weight and per square 

 metre of body surface. 



4. Calorie expenditure (indirect calorimetry). 



The following report form should be filled in as indicated, the necessary calcu- 

 lations being made by use of the tables in the appendix. 



METABOLISM SHEET. 



Name Age Wt. Ht. 



Surface area calculated = (Du Bois method). 



Corrected Volume of Respired Air. 



(1) Total volume of air respired in 15 min. = 100 Litres. 



(2) Actual Temp. = 20 C. 



