PLATE XII. 



(From Life and Evolution.) 



The barbs, barbules and barbicels of a flight-feather. A and 

 C x 90 diameters ; B x 250. A : A barb. C : A pair of barbs 

 showing interlocking. B : A pair of barbules, showing the barbi- 

 cels on the one nearer to the tip of the feather. 



To face p 86. 



