A MANUAL OF ZOOLOGY 77 



the microscope. Are there any true hairs on the bird? 

 Pluck a part of the body bare. Are all parts equally cov- 

 ered with feathers? Is there any regular arrangement of 

 feathers to be deduced from the appearance of the plucked 

 •portion? Remove the upper tail coverts and note the large 

 oil gland. What is its use? Slit open the skin from the 

 chin to the eloa,cal opening, and carefully remove it. Down 

 the front of the neck note the trachea. To the right of 

 this find the oesophagus. Open the mouth and inflate the 

 crop, a bag like expansion of the oesophagus by blowing 

 into the oesophagus with a blow pipe. What is the use 

 of the crop? Find the jugular veins and the vagus nerve 

 in the neck. In the median line of the chest find the keel 

 of the sternum. The sides of this serve as attachments 

 for the pectoralis major and minor muscles. Are they 

 much developed? Where are they inserted and what is 

 theif use? Sever them from their attachment at the keel 

 and dissect them away. Scrape the flesh carefully from 

 the large sternum and connected bones. Note a V-shaped 

 bone, the furculum or wish bone, with the apex attached 

 to the most ventral and interior part of the keel. This 

 bone is composed of the two clavicles grown together at 

 their sternal ends. The pair of bones attached to the an- 

 tero-lateral angles of the body of the sternum at their 

 proximal, and to the shoulder at their distal ends are the 

 coracolds. Note the ribs attached to the sides of the ster- 

 num. Remove the sternum very carefully by disarticu- 

 lating it from the furculum and the coracoids and by cut- 

 ting the ribs on each side. Inflate the lungs and the air 

 sacks in the body cavity by blowing into the trachea. How 

 does the bird breath? Is there any residual air left in the 

 lung between breaths? The temperature of the blood is 

 higher in birds and the pulse more rapid than in other ani- 

 mal forms. From the structure of the breathing apparatus, 

 would you expect this? Why? Trace the trachea to its 

 division into bronchi. Near the division on the trachea 

 note a swelling. This is the syrinx, or voice organ of 

 birds. Notice the heart and the pericardium. Slit the 

 latter open. Cut off the posterior end of the heart. Are 

 the two ventricles separated? Which is the stronger? 

 What is the shape of each? How many auricles are there? 



