16 EVOLUTION OF BIRDS. 
ers, Woodhewers, and Swifts, even some Finches and 
the Bobolink, that use their tail to support them when 
perched on swaying reeds, have the feathers more or 
less pointed and stiffened. Furthermore, this is just the 
result we should expect from a habit of this kind. But 
Fie. 3.—Tip of tail of (2) Downy Woodpecker and of (6) Brown Creeper, to 
show the poinved shape in tails of creeping birds of different families. 
(Natural size.) 
I do not understand how the Woodpecker’s spear-tipped 
tongue could have resulted from the habit of impaling 
grubs, and in this case I should be inclined to regard 
structure as due to a natural selection which has pre- 
served favorable variations in the form of this organ. 
I have not space to discuss this subject more fully, 
but trust that enough has been said to so convince you 
of the significance of habit, that when you see a bird in 
the bush it will not seem a mere automaton, but in each 
movement will give you evidence of a nice adjustment 
to its surroundings. Remember, too, that evolution is a 
thing of the present as well as of the past. We may not 
be able to read the earlier pages in the history of a species, 
but the record of to-day is open to us if we can learn to 
interpret it. 
This may be made clearer, and the importance of a 
study of habit be emphasized, if I briefly outline ‘the rela- 
tion between the wings, tail, feet, and bill of birds and 
the manner in which they are used. We are in the field, 
not in the dissecting room; our instrument is a field glass, 
‘ not a scalpel, and in learning the functions of these four 
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