412 ADVANCED PHYSIOLOGY 



Page 193. Arrange a bell jar of the type shown in Figure 102; or 

 let the long stem of a Y-tube pass through the cork and represent the 

 trachea, the two short branches representing the bronchi. Attach to 

 each " bronchus " a small rubber bulb, such as is on the mouth-piece affair 

 used by small boys as a " squawker." Close the lower end of the bell 

 jar with a sheet of rubber (obtainable from any dentist). By pushing the 

 rubber " diaphragm " upward, its position when the breath is expelled 

 is imitated, and the "lungs " collapse; when drawn down, air fills the 

 " lungs." The leakages around the cork can be stopped by use of melted 

 paraffin. 



Page 197. The capacity of the lungs, amounts of tidal air, comple- 

 mental air, etc., can be effectually shown by use of thin wooden or paste- 

 board boxes of sizes to represent the different volumes referred to. 



Page 201. Show changes in air enumerated here as follows : 

 a. With air pump, syringe bulb, or bicycle pump, force the ordinary air 

 of the room through a large test tube of limewater, by conducting the air 

 through a tube to bottom of water so that the bubbles rise through it. 



6. With a glass tube in the mouth blow through limewater. The cal- 

 cium carbonate formed can be dissolved with a little hydrochloric acid. 



c. Breathe on the thermometer bulb. 



d. Moisture is left on clean, cold glass when it is breathed upon. 



e. Exhale through a glass tube into strong sulfuric acid for some time ; 

 the acid turns black on account of organic matter in the breath. Extreme 

 care should be taken not to draw the acid into the mouth. 



Page 205. That CO 2 is heavy and will not support combustion can 

 be shown by leading that gas from a generator into the bottom of a pint 

 fruit jar, for instance ; it will drive out the air by collecting under it, thus 

 showing its weight. A lighted splinter thrust into it will go out. If a 

 piece of candle be placed in the bottom of a beaker and lighted, CO2 can 

 be poured into the beaker and the flame extinguished. See Appendix 

 list of formulae and methods. 



Page 206. To prove the fact of adjustment of breathing to different 

 circumstances, have students count rate of breathing when quietly sitting, 

 just after running up stairs and back, and before getting up in the morning. 

 Averages struck from a large number of such reports will be interesting. 



Page 210. If possible, the larynx of a sheep, calf, or dog should be 

 shown and dissected; This organ in a smaller animal is not large enough to 

 be of any value. Models of this organ can be bought (see list of dealers in 

 models) or one may be made from modeling wax, or carved from a 



