Feathers 



37 



quill — round where the body or body-feat hoi's fonceal 

 it, square where it supports the vane, — and nianv otlicr 

 niceties which we can each detect for oui'seKcs, sliow 

 how exquisitely exact is the adaptation of a feather to 

 its uses. 



Fig. "24. — Powtler-dowii patch on the Ineast of a li\e fireat White Heron. 



J 'A natural .^ize. 



Growinoj from the under side of the quill, at the be- 

 ginning of the vane, is a tiny feather known as the after- 

 shaft. In an ordinary down-feather of a young bird this 

 is of considerable size, but it is either small or entirely 

 absent iu an ordinary feather. It reaches its greatest 

 development in the emeu and the cassowar}% where it is 



