56 DISSECTION OF LUNG. 



remain distended. In holding up the lungs, take hold of the 

 windpipe above where it is tied, and not of the faucet. Note 

 (a) the conical shape of the whole ; compare this with the 

 chest cavity, as shown in a skeleton ; (&) how the lungs nearly 

 surround the heart ; (c) the concave posterior surface of the 

 lungs where they fitted the convex anterior surface of the dia- 

 phragm ; (d) the groove between the dorsal surfaces of the 

 lungs in which the spinal column fitted ; (e) the smooth, un- 

 divided dorsal surface of the lungs, and their division ven- 

 trally into Lobes ; (/) the relative lengths of the dorsal and 

 ventral surfaces of the lungs. The anterior end of the lung is 

 the Apex; the posterior end is the Base. Open the valve of 

 the faucet. What makes the air go out ? Again inflate. Does 

 it require effort to do so ? Why ? Cut off the end of one 

 lobe and again inflate. Does the air escape ? Throw a piece 

 of lung on water. Pinch a piece of lung, holding it near the 

 ear. The smooth, moist, glistening membrane covering the 

 lung is the Pleura. 



5. Observe a large whitish or yellowish tube running in 

 the groove between the dorsal surfaces of the two lungs. It 

 is usually covered with fat, and if it has been cut off short 

 its open end is easily seen near the windpipe. This is the 

 main artery, the Aorta. Take hold of its free end, and sepa- 

 rate it from its attachment to the other tissues, cutting close 

 to it with the scissors, so far as where it arches over the root 

 of the left lung. Now turn the free end forward. 



6. Find where the gullet is cut off posteriorly ; slit it open 

 for an inch or two, and note its whitish lining, the Mucous 

 Coat. The thick red coat is the Muscular Coat ; try to dis- 

 tinguish an inner layer of circularly arranged muscle fibers 

 and an outer longitudinal layer. Beginning posteriorly, sep- 

 arate the gullet from the windpipe, cut off the windpipe about 

 the middle, and entirely remove the gullet and larynx. 



