ELEMENTARY EXPERIMENTAL PHYSIOLOGY 73 



is experienced ; then allow respirations to recur and be recorded. 

 Measure the length of the absence of breathing. Stop the drum. 



Now breathe deeply and forcibly for about 2 minutes, so as to 

 clear the CO 2 out of the blood, starting the drum and thus recording 

 the last two or three respirations. Then hold the breath as above, 

 and measure the length of the absence of breathing, and compare 

 it with the last. Another student should observe any change in 

 the appearance of the face, and must count the pulse for half a 

 minute before and again after the forced breathing. 



(2) Count the pulse and record its rate. Run several times up 

 and down stairs to increase the CO 2 in the blood, and again record 

 the respirations from the nostril and count the pulse, recording the 

 rate. Compare the tracing and the pulse rate with those taken at 

 rest, and draw your conclusions as to the influence of muscular 

 exercise on the breathing and on the rate of the heart. 



(Read Text Book on the Regulation of Breathing.) 



(IV. of Lesson XIII. is best done at this time.) 



Lesson XVI. To be provided for each pair of Students. 



1. Measuring tape. 2. Cyrtometer. 3. Piece of glass. 4. Vessel of lime 

 water. 5. Vessel with very dilute potassium permanganate. 6. Bell-jar 

 with candle and tube attached for breathing through. 7. Stethoscope. 

 8. Lungs of rabbit and cat with tube tied in trachea. 9. Marey's recording 

 tambour on stand with tube and small balloon fitted to glass tube : a T tube 

 with clamp is useful. 10. Recording drum. 11. A vessel of lysol solution. 

 12. Water manometer. 



For Class. 



Microscope with section of lung stained with orcein to show the elastic 

 tissue. 



