with the dull of eye and ear, the keen of scent with the
blunt of scent--which we call natural competition; but the slow, the
stupid, the dull-eyed, dull-eared, and dull-scented find their place and
thrive for all that. They are dull and slow because they do not need to
be otherwise; the conditions of their lives do not require speed and
sharpness. The porcupine has its barbed quills, the skunk its pungent
secretion. All parts of nature dovetail together. The deer and the
antelope kind have speed and sharp senses because their enemies have
speed and sharp senses. The small birds are keen-eyed and watchful
because the hawks are so, too. The red squirrel dominates the gray
squirrel, which is above him in size and strength, and the chipmunk
below him, but he does not exterminate either. The chipmunk burrows in
the ground where the red cannot follow him, and he lays up a store of
nuts and seeds which the red does not. The weasel easily dominates the
rat, but the rat prospers in spite of cats and traps and weasels.

The sifting of species is done largely by environment, the wet, the
cold, the heat--the fittest, or those best adapted to their environment,
survive. For some obscure reason they have a fuller measure of life than
those who fall by the way.

III. HEADS AND TAILS

I have heard a story of a young artist who, after painting a picture of
a horse facing a storm, was not satisfied with it, and, feeling that
something was wrong, asked Landseer to look at it. Instantly the great
artist said to him, "Turn the horse around."

The cow turns her head to the storm, the horse turns his tail. Why this
difference? Because each adopts the plan best suited to its needs and
its anatomy. How much better suited is the broad, square head of the
cow, with its heavy coating of hair and its ridge of bone that supports
its horns, to face the storm than is the smooth, more nervous and
sensitive head of the horse! What a contrast between their noses and
their mode of grazing! The cow has no upper front teeth; she reaps the
grass with the scythe of her tongue, while the horse bites it off and
loves to bite the turf with it. The lip of the horse is mobile and
sensitive. Then the bovine animals fight with their heads, and the
equine with their heels. The horse is a hard and high kicker, the cow a
feeble one in comparison. The horse will kick with both hind feet, the
cow with only one. In fact, there is not much "kick" in her kind. The
t