Lastly, there is variety among not only the different species of plants, animals, insects, etc., but also the individuals of the same species. We ourselves know the differences there are between one man and another, and as far as that goes between ourselves on one day and ourselves on the next. Each plant—and still more each animal—has its own unique individuality. Every cavalry officer, every shepherd, every dog-owner, every pigeon-fancier knows that each horse, sheep, dog, pigeon has its own individuality and is distinctly different from all others of its kind. And so does every gardener know that each rose, each tulip, each pansy is different from all other roses, tulips, and pansies. It is the same in the forest. Hardly two trees or plants of the same species develop their young leaves, open their flowers, ripen their seeds, and drop their leaves at the same time. Apart from the size of the flower and leaf there are differences in colour, shape, and marking. Each in appearance and in habit has an individuality of its own.
Such is the variety in the abundant life of the forest that no two individuals, no two blades of grass, or no two leaves are in every detail precisely alike. And this is the second outstanding impression we receive.
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The abundance and variety of life are evident enough. Not so evident but equally noteworthy is the intensity. In the still forest one of the giant trees looks utterly impassive and immobile. It stands there calm and unmoved. Not a leaf stirs. Yet the whole and every minutest part of it is instinct with intensest life. It is made up of countless microscopic cells in unceasing activity. Highly sensitive and mobile cells form the root-tips and insinuate their way into every crevice in search of food for the tree, rejecting what is unpalatable and forwarding what is useful for building up and sustaining the monarch. Other cells take in necessary food from the air. Others build up the trunk and its protective bark. Others, and most important of all, go to make up the flowers of the tree and the organs of reproduction which enable the tree to propagate its kind.
All this activity of the separate cells and combinations of cells is taking place. And in addition there is that activity of them all in their togetherness, that activity which keeps the cells together, and which if relaxed for a moment would mean that the cells would all collapse as the grains of dust in an eddying dust-devil at a street corner collapse once the gust of wind which stirred them and keeps them together drops away. What must be the intensity of life required to develop the tree from the seed and to rear that giant straight up from the level soil 200 feet into the air and maintain it there two hundred years, we can only imagine; for to outward appearance the tree is quite impassive. It does not move a muscle of its face to reveal the intensity of life within.
The tree is characteristic of every living thing. Every plant and every animal, however seemingly sluggish, is working to fulfil its life, to nourish itself, to reproduce its kind.
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Now, the amount of air and sunshine for plants may be practically unlimited, but air and sunshine are not all that plants require. They want soil and moisture as well. And the standing-room for plants is strictly limited. The forest stretches away up to the snows; but there it stops. Necessarily, therefore, there must be the keenest and most incessant struggle among the plants for standing-room. Only a comparatively few can be accommodated. The rest cannot survive. And as the number of plants which can survive is thus limited, the number of animals is limited also, for animals are dependent on plants. Plants, therefore, in spite of their eminently pacific appearance are engaged in a fierce struggle with one another for standing-room. And animals are likewise engaged in a struggle among themselves for the plants.
There is competition among the roots of the different individual plants for the food and water of the soil. And there is competition among the leaves for the sunlight. Each plant is pushing its roots downwards and spreading outward for more food and to root itself more firmly. Each is straining upward to receive more sunlight. Each is struggling with its fellows for room and means to develop its life. Competitors in hundreds and thousands are forced to withdraw and succumb. And even when a forest giant has defeated all competitors and reached its full maturity it has still to maintain the struggle and hold its own continually against other individuals whose roots are reaching out below and whose branches are spreading out above; against climbers who would smother it; and against parasites who would suck its very life-blood. The battle, moreover, is often not so much between one species and another species as between individuals of the same species. And it is a war which continues through life.
The struggle for existence among the plants and trees is keen beyond imagination. And the struggle among the insects, birds and beasts, and man for the plants and products of the trees is no less severe. So now our impression is that of an abundant, varied and intense life in which the individuals are perpetually struggling with one another for bare existence.