APPENDIX TO CHAPTER XV. 



APPENDIX TO CHAPTER XV. 



1. A sheep's lungs with the windpipe attached may be readily ob- 

 tained from a butcher. It is best to secure them and the heart all 

 together, as unless the heart be carefully removed holes are apt to 

 be cut in the lungs. 



2. Examine the windpipe, and trace it down to its division into the 

 brondii. In the wall of the windpipe note the horseshoe-shaped 

 cartilages which keep it open, and which are so arranged that the 

 dorsal aspect of the tube (which lies against the gullet) has no hard 

 parts in it. 



3. Trace the main right bronchus to its lung, and then, cutting 

 away the lung-tissues, follow the branching bronchial tubes through 

 the organ. Note the cartilages in their walls. In the sheep there is 

 a small extra bronchus on the right side, which goes to the upper 

 part of the right lung. It is not present in man. 



4. Carefully divide the left bronchus where it joins the windpipe, 

 and lay it and its lung aside. Then slit open the trachea, the bronchus 

 still attached to it, and the bronchial tubes. Observe the soft pale-red 

 mucous membrane lining them. 



5. In the left bronchus, which has still an uninjured lung attached 

 to it, tie air-tight a few inches of glass tubing of convenient size. 

 On the end of the glass tube then slip a few inches of rubber tubing. 

 On blowing through the rubber tube the lung will be distended, and 

 as soon as the opening is left free it will collapse; in this way its 

 great extensibility and elasticity will be seen. 



6. Blow up the lung moderately, and while it is distended tie a 

 string very tightly around the bit of rubber tubing. This will keep 

 the air from escaping; the distended lung can now be examined at 

 leisure, and its form, lobes, and the smooth moist pleura covering it 

 be better seen than when it is collapsed. 



7. The diaphragm may be readily seen in the body of any small 

 animal (rat, kitten, puppy), on removing the abdominal viscera. The 

 liver and stomach must be cut away with especial care. 



a. When the above viscera are removed, the vaulted diaphragm will 

 be seen, and through it the pink lungs. 



b. Pull the diaphragm down, imitating its contraction and flattening 

 in inspiration. The lungs will be seen to follow it closely, expanding 

 to fill the space left by it in its descent. 



c. Make a free opening into one side of the thorax. The corre- 

 sponding lung will collapse, and be no longer influenced by move- 

 ments of the diaphragm. 



d. Now open the other side of the chest: its lung also shrinks up; 

 the structure of the diaphragm (its tendinous centre and muscular 

 sides) can now be better seen, as also the attachment of the pericar- 

 dium to its thoracic side. 



