Such vigilance over the ever-dying is very comforting—and marvelous too. Let any indifferent apple-tree begin to have holes, and the tree-toads, the bluebirds, and the red squirrels move in, to fill the empty trunk with new life and the sapless limbs with fresh fruit. Let any tall, stray oak along the river start to die at the top, and straightway a pair of fish-hawks will load new life upon it. And these other, engrafted lives, like the graft of a greening upon wild wood, yield crops more valuable often, and always more interesting, than come from the native stock.

Perhaps there is no more useless fruit or timber grown than that of the swamp-gums (Nyssa uniflora) of the Jersey bottoms. But if we value trees according to their capacity for cavities,—the naturalist has a right to such a scale of valuation,—then these gums rank first. The deliberate purpose of a swamp-gum, through its hundred years of life, is to grow as big as possible, that it may hollow out accordingly. They are the natural home-makers of the swamps that border the rivers and creeks in southern New Jersey. What would the coons, the turkey-buzzards, and the owls do without them? The wild bees believe the gums are especially built for them. No white-painted hive, with its disappearing squares, offers half as much safety to these free-booters of the summer seas as the gums, open-hearted, thick-walled, and impregnable.

When these trees alone make up the swamp, there is a roomy, empty, echo-y effect among the great gray boles, with their high, horizontal limbs spanned like rafters above, produced by no other trees I know. It is worth a trip across the continent to listen, under a clear autumn moon, to the cry of a coon-dog far away in the empty halls of such a swamp. To get the true effect of a barred owl's hooting, one wants to find the home of a pair in an ancient gum-swamp. I know such a home, along Cohansey Creek, where, the neighboring farmer tells me, he has heard the owls hoot in spring and autumn since he remembers hearing anything.

I cannot reach around the butt of the tree that holds the nest. Tapering just a trifle and a little on the lean, it runs up smooth and round for twenty feet, where a big bulge occurs, just above which is the capacious opening to the owls' cave. There was design in the bulge, or foresight in the owls' choice; for that excrescence is the hardest thing to get beyond I ever climbed up to. But it must be mounted, or the queerest pair of little dragons ever hatched will go unseen.

The owls themselves first guided me to the spot. I was picking my way through this piece of woods, one April day, when a shadowy something swung from one high limb to another overhead, following me. It was the female owl. Every time she lighted she turned and fixed her big black eyes hard on me, silent, somber, and watchful. As I pushed deeper among the gums, she began to snap her beak and drop closer. Her excitement grew every moment. I looked about for the likely tree. The instant I spied the hole above the bulge, the owl caught the direction of my eyes, and made a swoop at me that I thought meant total blindness.

I began to climb. With this the bird lapsed into the quiet of despair, perched almost in reach of me, and began to hoot mournfully: Woo-hoo, woo-hoo, woo-hoo, oo-oo-a! And faint and far away came back a timid Woo-hoo, woo-a! from her mate, safely hid across the creek.

"She turned and fixed her big black eyes hard on me."

The weird, uncanny cry rolled round under the roof of limbs, and seemed to wake a ghost-owl in every hollow bole, echoing and reëchoing as it called from tree to tree, to die away down the dim, deep vistas of the swamp. The silent wings, the snapping beaks, the eery hoots in the soft gloom of the great trees, needed the help of but little imagination to carry one back to the threshold of an unhacked world, and embolden its nymphs and satyrs, that these centuries of science have hunted into hiding.