3 I2 



RESPIRATION 



Expired Air. Take a large sample of expired air by breathing through 

 a large tube into a gallon aspirator bottle. This is large enough to hold 

 six or eight expirations. Now fill the gas buret with a sample of this expired 

 air and analyze as before, first for carbon dioxide, then for oxygen; com- 

 pute the percentage of each gas, including nitrogen. The expired air will 

 usually be found to have lost from 4 to 5 per cent, of oxygen and have gained 

 a little more than that quantity of carbon dioxide. 



From the percentages obtained in these experiments, and the volume of air 

 breathed per unit of time, computed in Experiment 4 above, determine the 

 amount of carbon dioxide exhaled per hour per kilogram of weight for your 

 own body. Compute also the amount of oxygen consumed. 



FIG. 2460. Arrangement of Tracheal Cannula and Marey's Tambour for Recording the 

 Chanoes in Intratracheal Pressure during Respiration. (Langendorff.) 



9. The Rate and Character of the Respiratory Movements in the 

 Mammal. a, The rate of respiration can be best determined by direct 

 count per minute, an effort being made to keep the animal under as nearly 

 normal conditions as possible; make the same determinations on a cat, a dog, 

 and a guinea-pig, b, The character of the respiratory movements can be 

 recorded by one of the various forms of stethograph adapted to the size of 

 the animal, or by the arrangement shown in figure 2460. It is necessary to 

 make the determination with the animal under the influence of an anesthetic. 



10. The Determination of Carbon Dioxide Given Off in the Mam- 

 mal. This determination can be made only by placing the animal in a res- 

 piratory calorimeter, and making the following measurements: 



a. The amount of air which passes through the animal chamber, the 

 calorimeter. 



b. The percentage of carbon dioxide in the air which is in the chamber. 



c. The percentage of carbon dioxide in the air which leaves the chamber. 

 If the animal is small enough, for example the guinea-pig or a mouse, 



