n6 Practical Zoology. 



1. Insert a large tube into the mouth and inflate the crop, com- 

 pressing the neck to prevent the escape of the air. Note the 

 shape of the crop. 



2. Beginning at the posterior end of the breastbone, cut through 

 the skin along the line of the ridge, or keel, of this bone, and 

 loosen the skin on each side, continuing forward over the crop, 

 being careful not to tear the crop ; again inflate the crop, and 

 examine it more fully. Observe the fine lines running crosswise 

 and lengthwise in the walls of the crop ; these are the muscle 

 fibers, transverse and longitudinal. 



3. Loosen the crop from the front of the breast and from the 

 neck. Find the windpipe, or trachea, with its white rings of 

 cartilage. 



4. On each side of the neck is the jugular vein. If it does 

 not show distinctly, let the bird's head and neck hang over the 

 edge of the table, and the vein will soon fill with blood. 



5. Close to the jugular vein is a white cord, the vagus nerve. 



6. Insert the tube into the glottis, and inflate ; observe the 

 swelling of the whole body, and the inflation of the thin-walled 

 air sacs in the hollow in front of the breastbone. 



7. Break the bone of the upper arm, the humerus ; cut through 

 the skin and muscles, and push out through this opening the end 

 of the bone next to the body ; note that it is hollow ; slip one end 

 of a rubber tube over the. end of the bone, and inflate ; what is 

 the result of this experiment? Keeping another tube connected 

 with the windpipe, determine whether air can be sent in through 

 the windpipe and out of the humerus, and vice versa. 



8. Slit the skin back over the abdomen to the anus, loosen 

 it well back on each side, and cut through the abdominal wall 

 just behind the breastbone ; inflate once more, and observe the 

 abdominal air sacs. 



9. Cut down into the muscle of the breast, close alongside 

 the ridge (keel) of the breastbone, and around the outer border 

 of the breastbone ; thus loosen and raise a great flap of muscle, 

 the pectoralis major. Note the nerve and blood tubes entering 





