APPENDIX. 259 



becomes bright-red oxyhaBmoglobin. The red corpuscles 

 of the blood are so many little boxes in which oxygen is 

 packed away in the lungs for conveyance to distant parts 

 of the body. 

 What is the function of the red blood-corpuscles? 



APPENDIX TO CHAPTER XVIL 



1. To show that air is warmed by breathing, breathe for a few 

 seconds on the bulb of a thermometer. The mercury will be seen to 

 rise rapidly in its stem. 



2. To demonstrate that air gains water in the lungs, breathe on a 

 mirror, or on a knife-blade or other polished metallic surface. 



3. The presence of carbon dioxide in expired air may be readily 

 demonstrated by expiring through a tube immersed in lime-water. 

 This may be obtained at any drug-store; with carbon dioxide it gives 

 a white precipitate, which dissolves readily in a little vinegar. 



4. To show that much less carbon dioxide exists in inspired air, 

 take a small bottle with a wide neck. Fit tightly into the neck of the 

 bottle a cork perforated by two holes. Through one hole pass a glass 

 tube reaching to near the bottom of the bottle, and through the other 

 one which ends just below the cork; on the outer end of this tube fit 

 a foot or so of rubber tubing. Remove the cork; half fill the bottle 

 with lime-water and then replace the cork. Suck air through the 

 rubber tubing. It will bubble through the lime-water, but (unless 

 the room is very badly ventilated) a great deal must be drawn through 

 the lime-water before as abundant a precipitate is produced as that 

 which results from blowing a small quantity of breathed air (3) 

 through the lime-water. 



5. The influence of oxygen upon the color of the blood may be 

 illustrated as follows: 



a. Take to a slaughter-house a glass jar or beaker (an ordinary 

 tumbler answers quite well), two bottles, an earthenware quart pitcher, 

 and a bundle of wire. 



b. When an animal is killed and bled, collect some blood in the 

 jar and let it clot. 



c. Collect some more blood in the pitcher, and defibrinate by 



