only purpose that flying serves. Later on it enables the animal to
pass from one food locality to another. In a few creatures it plays an
effective part during the mating season. These last are probably both
derived powers, and the original function was that of escape from the
enemy. The grasshopper has grown its long legs to serve him for
safety, and through them it is helped along, moving about chiefly by
leaps when it wishes to go any material distance. It is only toward
the very end of its life that the grasshopper has wings, and then they
serve probably to aid in the search for a mate. Among the birds flight
began simply in sailing out of the trees, into which the creature,
still half lizard, had crept to escape its enemy. The earliest bird
known to us had comparatively insignificant wings. There was really
more support in its tail than in its wings, and this would distinctly
indicate that it glided more than it flew. It had claws also upon its
wings, and it was probably the case that this creature crept into the
trees, at least in its earliest forms, and sailed down in a manner not
unlike that employed to-day by the flying squirrel. From such simple
beginnings came the wonderful power of flight in the birds.

Among mammals the attempt to escape from the enemy has led to an
interesting development, which will be more fully explained in a later
section when we speak of the history of the horse. The early mammals
walked flat-footed, as we do on our feet and as the raccoon and the
bear do on theirs. Gradually, however, as their enemies became more
fierce and better able to injure the larger mammals, the latter gained
in power of flight, and this gain consisted first in rising from the
toes, lifting the heels completely off the ground. At the same time
the leg and foot were gradually lengthened. Doubtless in this way the
fleet animals, like the deer, the horse and the giraffe, first came by
their long legs. Constant elimination of the short-legged ones, by the
pursuing enemy, resulted in the selection of the long-limbed ones for
breeding purposes, and hence to the ultimate elongation of the legs of
the species.

The method of escape from the enemy involves cowardice. "He who fights
and runs away may live to fight another day," and so it may be the
part of wisdom in the weak creature to escape from his enemy by
flight. It is a far more estimable process, from our standpoint at
least, to stand against the onslaught of