168 



ANIMAL SKETCHES. 



CHAP. XII. 



form the broad vane of the feather. You will find that 

 the barbs adhere together so that they cannot be separ- 

 ated without the application of some gentle force, upon 

 which they suddenl}- tear asunder. When the continuity 

 of the vane has thus been broken, simple pressing of the 

 separated barbs together will not mend it ; but if the 

 lower part of the broken vane be raised and hitched over 

 the part nearer the feather-tip the barbs will adhere 



-IWiroad barbuU) 



ad.l> 



DETAILS OF BIRD'S WING. 



together, and the broken vane will be mended. Why is 

 this ? If you look at a piece of a feather under a micro- 

 scope you will see why. Each barb is fringed on either 

 side with smaller barbs or barbules, and those nearer the 

 feather-tip have minute hooks which cling to the little 

 barbules of the adjoining barb. When we mend a broken 

 vane in the way I have described, we hitch these invisible 

 hooks over a series of invisible bars. In the feathers of 

 the ostrich, however, the barbules are long and loose, and 



