CHAPTER XXIX. 
PROFIT AND LOSS IN THE BIRDS. 
We have seen that birds in growing to be birds 
have lost much; in growing to be better birds they 
have lost more. With them, as elsewhere, loss often 
has its compensations, and has been the means of 
gain. 
They have mounted higher, in some instances, on 
part of “their dead selves” at least. Let us look 
back a little: 
They flew first by the loss of a pair of legs, or the 
use of their fore limbs as such, and they flew better 
by losing some fingers, perhaps, and at least the sep- 
arate use of all; better still, by the loss of tail, or its 
great length at least. 
After they became runners and used their wings 
less, such of them as depended on escape afoot lost 
most of the fibula, or the smaller of the leg bones, 
that they might run better. Likewise, later they lost 
some muscles that were necessary in running, swim- 
ming, or moving the tail even; and they had various 
adhesions of the tendons in keeping with their wants. 
They took on certain organs as they had need, 
and lost these new ones as readily when they became 
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