26 THE STORY OF THE BIRDS. 
certain it is that there are many degenerate feathers— 
especially noticeable in such flightless birds as the 
apterye and others, where the plumage has lost its 
hooks and become slightly hairlike. Some of these 
degenerations are a source of great beauty, as seen in 
the plumage of peacocks, lyre birds and others, where 
the loss of some part of the feather produces the flossy 
effect. Similarly in the so-called bristles about the 
beak the feather has lost everything but barrel and 
shaft. There are many of these among the dense 
plumage also. 
So in its degenerate condition, if such it be, a 
bird’s underwear may be made extremely ornamental 
at places where it can show, as ours does in cuffs, col- 
lars and frills, sometimes. This is especially notice- 
able in the condor’s ruche of down about the neck 
and on the cottony tufts about the flanks of some 
smaller birds, which seem to have antedated the 
modern charmer in exhibiting just the daintiest bits 
of tantalizing white in a very effective manner. 
Nay, it may be that the birds have outdone us in 
another respect here. In the herons and their kin, in 
the goatsucker group and others (usually nocturnal) 
are found, rather symmetrically placed, certain tracts 
of downs that are constantly undergoing slow oxida- 
tion or breaking down into powders which usually 
show externally. Some of these are front only, some 
are rear and some birds have them at both places. 
Their purpose has not been determined yet, but it 
has been asserted that in herons at least these spots 
are phosphorescent at night, and that fish are thereby 
