THE ENGLISH SPARROW. 1 1 9 



The following notes will serve to guide the student in a study of the 

 internal anatomy: 



a) Just beneath the skin of the neck is an enlargement of the oesopha- 



gus forming the crop. Insert a blow-pipe into the opening of the 

 oesophagus in the mouth and inflate the food tube, noting its dis- 

 tensible quality. 



b) Under the crop is the trachea, or air tube, with its rings of cartilage. 



Inflate this also, by inserting the blow-pipe in the glottis, and 

 observe the swelling of the whole body. Now break the bone of 

 the upper-arm humerus in one of the wings, push back the 

 skin and flesh from the end next the body and slip a piece of 

 rubber tubing over it. Blow into the latter and note results. 

 Can you force air through the glottis? Can you force air from 

 the glottis through the wing bone ? If a sound is produced in 

 either experiment, account for it. 



c) Along the neck on either side of the trachea is a dark-colored 



jugular vein and closely associated with it a white nerve cord 

 with several side branches. This is the pneumogastric nerve. 

 Trace both vein and nerve as far as practicable. Note the 

 thyroid glands in the same region. 



d) It will be observed that the prominence of the breast region is due to 



the very large pectoral muscle which moves the wings in flight. 

 It has a right and a left division, the two separated by the promi- 

 nent central keel of the breastbone or sternum. 



e) Feel for the right and left coracoid bones acting as braces be- 



tween the front angles of the breastbone and the shoulders. Be- 

 tween these, its two forks meeting at a point just ahead of the 

 sternum, is the V-shaped furcula or wish-bone. What is its 

 representative in human anatomy ? Where are the coracoid bones 

 in the human skeleton. 



f) After cutting carefully through the thin abdominal wall where it 



borders the posterior edge of the sternum, inflate the trachea 

 again and note the swelling of the thin-walled air sacs in the ab- 

 dominal region. Do you notice any air sacs also in front of the 

 breastbone ? There are several pairs of these sacs and all play an 



