Great gaps would be made in the ranks of the furry creatures--the mammals. Opossums and raccoons would find themselves in an embarrassing position, and as for the sloths, which never descend to earth, depending for protection on their resemblance to leaves and mossy bark, they would be wiped out with one fell swoop. The arboreal squirrels might learn to burrow, as so many of their near relations have done, but their muscles would become cramped from inactivity and their eyes would often strain upward for a glimpse of the beloved branches. The bats might take to caves and the vampires to outhouses and dark crevices in the rocks, but most of the monkeys and apes would soon become extinct, while a chimpanzee or orang-utan would become a cripple, swinging ever painfully along between the knuckles of crutch-like forearms, searching, searching forever for the trees which gave him his form and structure, and without which his life and that of his race must abruptly end.
Leaving the relations which trees hold to the animals about them and the part which they have played in the evolution of life on the earth in past epochs, let us consider some of the more humble trees about us. Not, however, from the standpoint of the technical botanist or the scientific forester, but from the sympathetic point of view of a living fellow form, sharing the same planet, both owing their lives to the same great source of all light and heat, and subject to the same extremes of heat and cold, storm and drought. How wonderful, when we come to think of it, is a tree, to be able to withstand its enemies, elemental and animate, year after year, decade after decade, although fast-rooted to one patch of earth. An animal flees to shelter at the approach of gale or cyclone, or travels far in search of abundant food. Like the giant algæ, ever waving upward from the bed of the sea, which depend on the nourishment of the surrounding waters, so the tree blindly trusts to Nature to minister to its needs, filling its leaves with the light-given greenness, and feeling for nutritious salts with the sensitive tips of its innumerable rootlets.
Darwin has taught us, and truly, that a relentless struggle for existence is ever going on around us, and although this is most evident to our eyes in a terrible death battle between two great beasts of prey, yet it is no less real and intense in the case of the bird pouring forth a beautiful song, or the delicate violet shedding abroad its perfume. To realise the host of enemies ever shadowing the feathered songster and its kind, we have only to remember that though four young birds may be hatched in each of fifty nests, yet of the two hundred nestlings an average often of but one lives to grow to maturity,--to migrate and to return to the region of its birth.