THE BUILDING OF A BIRD 27 



acting like a rudder to steer with. Perhaps the small 

 ones too, all over the body, are of some help in flight, 

 because they make a bird smooth, so that it can cut 

 through the air more easily — you know they all lie 

 one w^ay, pointing backward from their roots to their 

 tips. Then when Kap said feathers keep a bird 

 warjn, he guessed right. Birds wear plumage as you 

 do clothes, and for the same purpose — to look nice 

 and keep warm." 



" But what is ' plumage,' Uncle Roy ? " asked Dodo ; 

 "I thought you were talking about feathers." 



'' So I was, missy. Feathers are the plumage, when 

 you take them all together. But see here," added the 

 Doctor, as he spread the Sparrow's wings out, and held 

 them Avhere the children could look closely ; " are the 

 Avings all plumage, or is there something else ? " 



" Of course there's something else to wings," said 

 Dodo ; '' meat and bones, because I've eaten chickens' 

 wings." 



'' Why didn't you say. Dodo, because there has to 

 be something for tlie feathers to stick into ? " said Nat 

 decidedly. 



" You both have very good reasons," said the Doctor. 

 " The plumage of the wrings grows out from the skin, 

 just as feathers grow from any other part of the body, 

 only the large ones are fastened to the bones, so that 

 they stay tight in their proper places. If the}^ were 

 loose, they would fly up when the bird beats the air 

 with its wings, and get out of order. See how 

 smoothly they lie one over another ! When tlie bird 

 closes its wings, they come together snugly along its 

 sides. But when the wing is spread, they slide apart 



