22 



JEXTERNAL PARTS 



CHAPTER IV 



WINGS 



Use. — The general purpose of a wing is to be an organ of 

 flight, and in most birds this is its principal use.. In a few- 

 birds the body is too large and the wings are too small for 

 this office. This is true in the ostrich and a few swimming 

 birds. These use their wings to lighten their weight on the 

 ground and possibly to aid them in running. In a few species, 

 as in the penguins, the wings are not covered with feathers 

 and quills, but with scale-like parts. In these, the wings act 

 almost like the fins of fishes, and just like the paddles of 

 whales and of porpoises, and enable the bird to move through 

 the water almost if not quite as rapidly as any of the fishes. 



Some birds, as the divers, 

 the dippers, etc., use their 

 wings both for flight and 

 for swimming. Many birds 

 can use their wings as pow- 

 erful weapons in fighting, 

 and some have them fitted 

 with strong and sharp spurs 

 to render them the more 

 useful for this office. Most 

 birds make use of their 

 wings to protect their 

 young from enemies and 

 from storms. 



Parts. — The bones and the flesh of the wings consist of 

 four readily seen parts, — the up2xr arm, the forearm, the 

 pinion, and the tliumh. 



Feathers. — The quills or remiges are the stiffest, strongest, 

 and most pennaceous (pen-like) of feathers, and form the spread 



