148 THE STRUCTURE AND LIFE OF BIRDS chap- 



are smooth and hairlike, with only an occasional im- 

 perfect hook near the edge of the vane. Those on 

 the further barbules end, many of them, in perfect 

 little hooklets. By means of these the barbules of 

 two neighbouring barbs are locked together. 



Fig. 39 (after Pycraft). 

 To show method of interlocking. 

 A and B, Barhicels running in grooves ; c, Barhule on near side of barb : 

 on further side. 



Barbule 



If you look at a feather under the microscope, using 

 a not very high power, you will see that the barbules 

 on the distant side of the barb are not only hooked 

 but waved, and the smooth hairlike endings of the 

 opposite set that meet them are neatly tucked under- 

 neath into the hollow of the wave. It is not the case, 



