XXX 



INTRODUCTION 



Song-birds; while in others it is altogether wanting, 

 as in young Sparrows, and those of the Crow tribe. 



Only in the nestling-down of the Game-birds, 

 Ducks, and the Ostrich tribe is there found a forma- 

 tion of feathers known as the "after-shaft." This, by 

 the way, is a conspicuous feature in the adult feathers 

 of the Emu and Cassowary, where it forms a sort of 

 duplicate of the main-shaft, equalling it in size ; while 

 among the higher birds it is never very large, except 

 in the Game-birds (Fig. 6) , but even here it is downy 

 in texture, and is always shorter than the main- 

 shaft. 



As touching the growth of feathers, but little can 

 be profitably said here. The earliest traces of feathers 

 must be sought for in the embryo, where the first rudi- 

 ments of the coming nestling-doAvn appear in the form 

 of tiny bead-like bodies, which soon sink down into a 

 pit. Next an outer pro- ^f/ve 

 tecting sheath is devel- 

 oped around this feather 

 rudiment, and within 

 this the mass of pulp 

 which it contains pro- 

 ceeds to form first the 

 main axis, and next the 

 barbs and barbules. 

 What will prove the tip 

 of the feather is the first 

 to be formed, and as this 

 forces its way up, the 

 lower parts are added, 



Mlif^ S/tfifT 



J^ojY/vy'Bi^ifSs 



Afir£ii^»/ifiT.. 



Qu/LL. -•'■ 



Fig. 6. 



till at hatching-time the 



whole of the down feather is completed. 



