FEATHERS OF BIRDS. 



393 



at a, a, b, b, Fig. 226, as they arise from the two sides of 

 the edges of each lamina: they are exceedingly numerous, 

 above a thousand being contained in the space of an inch; 



and they are of two kinds, each kind having a different form 

 and curvature. Those marked a, a, which arise from the 

 side next to the extremity of the feather are branched or 

 tufted, and bend downwards, while those marked b, b, pro- 

 ceeding from the other side of the lamina, or that nearest 

 the root of the feather, are shorter and firmer, and do not 

 divide into branches, but are hooked at the extremities, and 

 Ifire directed upwards. When the two laminae are brought 

 close to one another, the long, curved fibrils of the one be- 

 ing carried over the short and straight fibrils of the other, 

 both sets becom.e entangled together; their crooked ends 

 fastening into one another, just as the latch of a door falls 

 into the cavity of the catch which is fixed in the door-post 

 to receive it. The way in which this takes place will be 

 readily perceived by making a section of the vane of a fea- 

 ther across the lam.ina^, and examining, with a good micro- 

 scope, their cut edges, while they are gently separated from 

 one another. The appearance they then present is exhibited 

 in Fig. 227, which shows distinctly the form, direction, and 

 relative positions of each set of fibrils, and the manner in 

 which they lay hold of one another. This mechanism is re- 

 peated over every part of the feather, and constitutes a close- 

 VoL. I. 50 



