49 THE STORY OF THE BIRDS. 
certain feathers (on certain birds), whereby they grow 
to immense length. 
As hinted, Nature has rather recently given some 
birds a paradoxical method of acquiring a new suit by 
wearing out its old one. What a convenient thing 
that would be for some of the rest of us! 
Much of the colors of a bird’s feathers—or the 
briliancy rather—is on the tips only. Beneath, fre- 
quently a contrasting color may prevail. Some of 
these tips fray easily or are actually shed—often in 
certain places only. This wear allows the color be- 
neath to show. The male English sparrow gets his 
black throat patch largely in this way, and the male 
bobolink puts on his wedding garment by taking off 
his traveling suit, though he has a spring molt also. 
Likewise some birds with faint external tints lose 
them in this manner, and some young birds get a new 
shape to the extremities of the flight quills thus. 
There are some other evidences that Nature has 
changed her first method of giving the bird a new 
suit. Now, usually the old feather closes at the lower 
end of the barrel, and, shutting itself off from nutri- 
ment, it really ceases to grow and falls out; but, as 
we have seen, the nestling downs, which probably 
type a very primitive state, are not so closed, but are 
pushed out on the tips of the forming adult feathers 
or adult downs. This is the case in all the subsequent 
molts of the cassowaries, which go about for a while 
with their old suit raggedly hanging to their new one. 
Molt therefore may, primarily, have begun as a 
renewal process rather than a destructive one, de- 
