RESPIRATION. 



127 



ting through with scissors the detached ribs near the breast-bone, 

 d removing them. The breast-bone will thus be left in its place, 

 upported by a rib or two at the top and bottom, and the division 

 f the chest into two halves by the pleura the heart lying in its 

 ag or pericardium as well as the appearance and position of the 

 lungs, will be seen. Great care must be taken in opening into 

 the chest, and in cutting the ribs posteriorly, not to injure the 

 lungs. To show the action of the lungs, the windpipe must now 

 be cut down upon in the neck, cut through, and detached, and a 

 small tube tied into it. When this is gently blown into, the lungs 

 will be seen to be inflated. A much more elegant mode of showing 

 their action, however, is, carefully to take out both windpipe and 

 lungs, and to attach them as represented in the following figure, 



c- 



Rabbit's lungs in a bottle. 



where a is a bottle, six or seven inches high, and about three wide, 

 such as is used by druggists, with the bottom cut off; b is the rab- 

 bit's lungs (with the windpipe left moderately long) tied to a 

 notched tin tube (c), that passes through a cork accurately fitting 

 the neck of the bottle ; d is a wooden piston, three-fourths of an 

 inch thick, covered with soft leather, which is stuffed with hair, 

 and oiled to make it fit accurately. When the handle of the piston 

 is drawn quickly down, the air rushes by the tube and windpipe 

 into the lungs, and inflates them, and this can be repeated by push- 

 ing the piston gently up, and then again drawing it quickly down. 

 The bottle must be of the same width throughout, and the lungs 

 must not be cut or injured in any part. The lungs should be in the 

 bottle, and the windpipe tied on the tube, before the cork is fitted 

 into the bottle. This is a remarkably striking experiment, and 

 should be seen by every one who wishes to form a just conception 

 of respiration. A pig's bladder will answer very well to show the 

 nature of respiration. A beautiful experiment may be performed by 

 procuring of a butcher a sound pair of calf's lungs, or lights, in 



