Experiment 114. To illustrate the arrangement of the lungs and the two pleurae. Place a large sponge which will represent the lungs in a thin paper bag which just fits it; this will represent the pulmonary layer of the pleura.  Place the sponge and paper bag inside a second paper bag, which will represent the parietal layer of the pleura.  Join the mouths of the two bags.  The two surfaces of the bags which are now in contact will represent the two moistened surfaces of the pleurae, which rub together in breathing.

Experiment 115. To show how the lungs may be filled with air. Take one of the lungs saved from Experiment 110.  Tie a glass tube six inches long into the larynx.  Attach a piece of rubber to one end of the glass tube.  Now inflate the lung several times, and let it collapse.  When distended, examine every part of it.

Experiment 116. To take your own bodily temperature or that of a friend. If you cannot obtain the use of a physician’s clinical thermometer, unfasten one of the little thermometers found on so many calendars and advertising sheets.  Hold it for five minutes under the tongue with the lips closed.  Read it while in position or the instant it is removed.  The natural temperature of the mouth is about 98-1/2 degrees F.

Experiment 117. To show the vocal cords. Get a pig’s windpipe in perfect order, from the butcher, to show the vocal cords.  Once secured, it can be kept for an indefinite time in glycerine and water or dilute alcohol.

  Experiment 118. To show that the air we expire is warm. Breathe
  on a thermometer for a few minutes.  The mercury will rise rapidly.

  Experiment 119. To show that expired air is moist.  Breathe on a
  mirror, or a knife blade, or any polished metallic surface, and note the
  deposit of moisture.

Experiment 120. To show that the expired air contains carbon dioxid.  Put a glass tube into a bottle of lime water and breathe through the tube.  The A liquid will soon become cloudy, because the carbon dioxid of the expired air throws down the lime held in solution.

Experiment 121.  “A substitute for a clinical thermometer may be readily contrived by taking an ordinary house thermometer from its tin case, and cutting off the lower part of the scale so that the bulb may project freely.  With this instrument the pupils may take their own and each other’s temperatures, and it will be found that whatever the season of the year or the temperature of the room, the thermometer in the mouth will record about 99 degrees F. Care must, of course, be taken to keep the thermometer in the mouth till it ceases to rise, and to read while it is still in position.”—­Professor H. P. Bowditch.

Experiment 122. To illustrate the manner in which the movements of inspiration cause the