Tropical midges of sorts live less than a day—sequoias have felt their sap quicken at the warmth of fifteen hundred springs. Somewhere between these extremes, we open our eyes, look about us for a time and close them again. Modern political geography and shifts of government give us Methusalistic feelings—but a glance at rocks or stars sends us shuddering among the other motes which glisten for a moment in the sunlight and then vanish.
We who strive for a little insight into evolution and the meaning of things as they are, forever long for a glimpse of things as they were. Here at my laboratory I wonder what the land was like before the dense mat of vegetation came to cover every rock and grain of sand, or how the rivers looked when first their waters trickled to the sea.
All our stories are of the middles of things,—without beginning or end; we scientists are plunged suddenly upon a cosmos in the full uproar of eons of precedent, unable to look ahead, while to look backward we must look down.
Exactly a year ago I spent two hours in a clearing in the jungle back of Kartabo laboratory, and let my eyes and ears have full swing.[2] Now in August of the succeeding year I came again to this clearing, and found it no more a clearing. Indeed so changed was it, that for weeks I had passed close by without a thought of the jungle meadow of the previous year, and now, what finally turned me aside from my usual trail, was a sound. Twelve months ago I wrote, "From the monotone of under-world sounds a strange little rasping detached itself, a reiterated, subdued scraping or picking. It carried my mind instantly to the throbbing theme of the Niebelungs, onomatopoetic of the little hammers forever busy in their underground work. I circled a small bush at my side, and found that the sound came from one of the branches near the top; so with my glasses I began a systematic search." This was as far as I ever got, for a flock of parrakeets exploded close at hand and blew the lesser sound out of mind. If I had stopped to guess I would probably have considered the author a longicorn beetle or some fiddling orthopter.
Now, a year later, I suddenly stopped twenty yards away, for at the end of the silvery cadence of a woodhewer, I heard the low, measured, toneless rhythm which instantly revived to mind every detail of the clearing. I was headed toward a distant palm frond beneath whose tip was a nest of Rufous Hermits, for I wished to see the two atoms of hummingbirds at the moment when they rolled from their petit pois egg-shells. I gave this up for the day and turned up the hill, where fifty feet away was the stump and bush near which I had sat and watched. Three times I went past the place before I could be certain, and even at the last I identified it only by the relative position of the giant tauroneero tree, in which I had shot many cotingas. The stump was there, a bit lower and more worn at the crevices, leaking sawdust like an overloved doll—but the low shrub had become a tall sapling, the weeds—vervain, boneset, velvet-leaf—all had been topped and killed off by dense-foliaged bushes and shrubs, which a year before had not raised a leaf above the meadow level. The old vistas were gone, the landscape had closed in, the wilderness was shutting down. Nature herself was "letting in the jungle." I felt like Rip Van Winkle, or even more alien, as if the passing of time had been accelerated and my longed-for leap had been accomplished, beyond the usual ken of mankind's earthly lease of senses.
All these astounding changes had come to pass through the heat and moisture of a tropical year, and under deliberate scientific calculation there was nothing unusual in the alteration. I remembered the remarkable growth of one of the laboratory bamboo shoots during the rainy season—twelve and a half feet in sixteen days, but that was a single stem like a blade of grass, whereas here the whole landscape was altered—new birds, new insects, branches, foliage, flowers, where twelve short months past, was open sky above low weeds.
In the hollow root on the beach, my band of crane-flies had danced for a thousand hours, but here was a sound which had apparently never ceased for more than a year—perhaps five thousand hours of daylight. It was a low, penetrating, abruptly reiterated beat, occurring about once every second and a half, and distinctly audible a hundred feet away. The "low bush" from which it proceeded last year, was now a respectable sapling, and the source far out of reach overhead. I discovered a roundish mass among the leaves, and the first stroke of the ax sent the rhythm up to once a second, but did not alter the timbre. A few blows and the small trunk gave way and I fled for my life. But there was no angry buzzing and I came close. After a cessation of ten or fifteen seconds the sound began again, weaker but steady. The foliage was alive with small Azteca ants, but these were tenants of several small nests near by, and at the catastrophe overran everything.
The largest structure was the smooth carton nest of a wasp, a beautiful species, pale yellowish-red with wine-colored wings. Only once did an individual make an attempt to sting and even when my head was within six inches, the wasps rested quietly on the broken combs. By careful watching, I observed that many of the insects jerked the abdomen sharply downward, butting the comb or shell of smooth paper a forceful blow, and producing a very distinct noise. I could not at first see the mass of wasps which were giving forth the major rhythm, as they were hidden deep in the nest, but the fifty-odd wasps in sight kept perfect time, or occasionally an individual skipped one or two beats, coming in regularly on every alternate or every third beat. Where they were two or three deep, the uppermost wasps struck the insects below them with their abdomens in perfect rhythm with the nest beat. For half an hour the sound continued, then died down and was not heard again. The wasps dispersed during the night and the nest was deserted.
It reminded me of the telegraphing ants which I have often heard in Borneo, a remarkable sweeping roll, caused by the host of insects striking the leaves with their heads, and produced only when they are disturbed. It appeared to be of the nature of a warning signal, giving me opportunity to back away from the stinging legions which filled the thicket against which I pushed.