Besides this struggle with the environment there is the struggle of individuals and of species with one another--of oak with oak, of beech with beech, of plant with its kind, for the moisture and nutriment in the soil; of robin with robin for insects and fruit, of fox with fox for mice and rabbits, and of lion with lion for antelope and zebra. I say “struggle,” but it is rarely struggle in the sense of strife or battle, but in the sense of natural competition--the victory is to the most lucky and the most vigorous--the sharpest eye, the quickest ear, the most nimble foot; and those most favored by fortune win. Under the law of variation some individuals have a fuller endowment of vital energy than others; under a severe strain and trial of whatever kind the favored ones will survive, while the others perish. Some men, some animals, can endure more hardships than others; under the same conditions all will not starve or freeze or fall exhausted by the wayside at the same time. In the vegetable world the same inequality in the gift of life exists, though not in the same degree. Some seeds will lie dormant in the soil longer than others of the same kind, and some kinds longer than others. Some seeds will not sprout after the second year, but a few may sprout after the third or even the fourth year. The stream of life is not of uniform depth and fullness; it is shallow in some places, and deep in others, as regards both species and individuals. In the natural competition which goes on all around us, the strongest, the fittest, win in the game, not necessarily by violence, but because, apart from the rôle played by chance, they carry more pounds of vital pressure. Not all acorns become oaks, probably not one in thousands; not all bird’s eggs become birds; occasionally one egg in the nest does not hatch, probably because of some defect in fertilization. Some nests are torn out of the trees by storms, or are robbed by crows or jays or squirrels; they were not well hidden. A large percentage of nests on the ground is destroyed by night prowlers or by day prowlers; chance again plays a great part here. Only a small fraction of the spawn of fishes hatches, and a still smaller percentage of the hatched ever reaches maturity. Fortune, good or bad, plays a great part with all forms of life. The acorn that becomes an oak owes much to chance--chance of position and soil, and chance of the vicissitudes of the woods and fields. Falling trees or branches, or the foot of a passing animal, may crush or deform it, or a squirrel or a raccoon devour it. Barring these accidents, it owes, or may owe, not a little to its inherent vitality--to its real oakhood.