358 The Bird 
The great Order of perching birds (Passeres) shows to 
what varied uses the typical foot can be put. All birds 
of this Order have three toes in front and one behind, 
and there is scarcely a place on the globe to which these 
birds have not adapted themselves; and recently too, 
as would seem probable from the similarity of the foot- 
type running through all. 
This very foot holds much of interest too, if we con- 
sider it from another point of view. Many apes and 
monkeys, and we ourselves, still have the five fingers and 
toes which we suppose was the number originally devel- 
oped upon the limbs of the vertebrate prototype; while 
horses and deer—animals much lower in the scale of 
life—have had the five original digits reduced to one 
or two. So among birds the ostriches and some other 
low forms have become extremely specialized in the same 
respect, possessing but two or three toes, while those 
birds which in mental and physical attributes excel all 
others of their Class are still more reptilian, and thus 
more primitive—more Archzopteryx-like—in possessing a 
larger number of digits—four. Thus when we speak 
of an animal as high or low in the scale of life, we must 
carefully distinguish between mere specialization and 
actual upward progress, mentally or physically, toward 
some ideal goal. The branch of a tree, which stretches 
horizontally farthest from the parent trunk, is not likely 
to be the one which reaches upward high enough to catch 
the first rays of the morning sun. 
The majority of the Passeres are arboreal and the 
strength of the tiny tendons which run down the leg and 
