Feathers 



37 



quill — round where the body or body-feathers conceal 

 it, square where it supports the vane, — and many other 

 niceties which we can each detect for ourselves, show 

 how exquisitely exact is the adaptation of a feather to 

 its uses. 



Fig. 24. — Powder-down patch on the liieast of a hve Great White Heron. 



2/3 natural size. 



Growing 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 co^siderable size, but it is either small or entirely 

 absent in an ordinary feather. It reaches its greatest 

 development in the emeu and the cassowary, where it is 



