148 THE STRUCTURE AND LIFE OF BIRDS cHapP: 
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. 
Fic. 39 (after Pycraft). 
To show method of interlocking. 
a and B, Barbicels running in grooves ; c, Barbule on near side of barb; p, Barbule 
on further side. 
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, 
