Within five minutes the daily downpour of tropical rain would drench the jungle. At this moment the air was tense with electricity, absolutely motionless, and saturated with odorous moisture. The voices of all the wild creatures were hushed. The sense of mystery which is always so dominant in a tropical jungle seemed nearer, more vital, but more than ever a mystery. Its insistency made one oblivious of the great heat. The beating of one's heart became a perceptible sound, absurdly loud. All the swamp and jungle seemed listening to it.

Suddenly a voice came out of the heart of this mystery, and fittingly enough, the voice seemed something a little more or less than human, and also fittingly it uttered but a single word, and that word a question. And the listener realized that the answer to the question was the only thing which made life and work worth while. The throb of the blood in his veins was forgotten, and all his senses reached out to the sights and sounds and scents about him. And again the great black frog called from its slimy seat hidden in the still blacker water of the jungle swamp. Its voice was deep, guttural, and a little inhuman, but it asked as plainly as any honest man could ask, Wh—y? And after a minute, Wh—y?

I squatted in the center of a trail. Within walking distance behind me flowed the yellow waters of the Amazon, and the igarapÉ from which the frog had called was even now feeling the tidal heave of the ocean. Ahead, the jungle stretched without a break for three thousand miles or more. And here for a week I had suffered bodily torture, twisting into unhappy positions for hours at a time, watching the birds which crowded the berry-laden foliage of a single jungle tree. In the cool of early morning, throughout the terrible breathless heat of mid-day and the drenching downpour of afternoon, the frog and I put our questions. There was hope in our interrogation. And my five senses all gave aid, and my hand wrote down facts, and my mind pondered them.

In the very suburbs of ParÁ, at the mouth of the great Amazon and within a hundred miles of the equator, I found a Mecca of bird-life. It was a gastronomic Mecca to be sure, a tall, slender, wild cinnamon tree,—canella do matto the natives called it. For a full week I invited torture by attempting to study the bird-life of this single tree. This thing had not been done before; it might not be worth the doing. But testing such possibilities are as important to a naturalist's work as following along the more conventional and consequently more certain lines of investigation. I had no time for exploration of the surrounding country; so I had determined to risk all my precious hours upon intensive observation in one spot.

The century before, a plantling had pushed up through the jungle mold and had won success in the terrible competition of the tropics—the helpless, motionless, silent strife of the vegetable folk. Year by year the lichen-sculptured trunk had pushed its way upward toward light and air, miraculously saved from the deadly embraces of the lianas which crawled forever through the jungle. Today it had gained an accepted place. Although no forest giant, with no great buttresses or masses of parasitic growths, it held up its branches and twigs in full sunlight a hundred feet or more above the ground. And its twiggy fingers were laden with a wonderful harvest of fruit, uncounted berries which attracted the birds from distant roosts and drinking places.

Here, then, a thousand combinations of fate had led me, and here I suffered day by day. Bound to the earth like other normal men, my eyes should have been directed forward. Now I forced them upward for hours at a time, and all the muscles of neck and shoulders revolted. Then eyestrain and headache and a touch of fever followed, and I cast about for means to ameliorate my bodily ills. I dragged a canvas steamer chair to my place of vigil and all my body was grateful.

In memory, there now remain only the highlights of new discoveries, the colorful moments of unalloyed realization of success. Nevertheless this new method of tropical work brought its own new delights and trials. One joy lay in the very difficulties to be overcome. Every sense came into play. Sight, first and foremost, had been put to the most severe of tests in attempting to record the happenings against the glare of the sky high up among the foliage of this bit of jungle. I strained through my high-power glasses, until, when I looked without them, the world seemed withdrawn, dwarfed, as in the horrid imaginings of fever. The glasses gained in weight as I held them pointing vertically until they fairly dropped from my aching arms. My ears strove to catch every song, every note which might prove a character of worth. The jungle scents played upon my emotions and sometimes dominated my work; the faint aroma from some invisible orchid overhead, the telltale musk from a passing mammal, the healthful scent of clean jungle mold. As for taste, I had tested the aromatic berries and fruit of my canella tree, and for science' sake had proved two warningly colored insects. My sense of feeling had operated involuntarily and wholly aside from my scientific desires. Whether stimulated by dozens of mosquitoes, scores of ants, or hundreds of bÊtes rouges or "mucuims," the insistency of discomfort never discouraged a primary desire to delve as deeply as possible into the secrets of this small area of tropical jungle.

As I walked slowly about beneath the tree or lay back resting in the chair, I seemed to be watching creatures of another world. Whether I ogled them with glasses or now and then brought one down with a charge of small shot, I was a thing of no account to the berry-eating flocks high overhead. A vulture soaring lower than usual passed over the tree, and the shadow of his partial eclipse of the sun froze every bird to instant silence and complete immobility. But my terrestrial activities wrought no excitement. The shot whistled through the foliage, one of their number dropped from sight, and life for the rest went on without a tremor. To ancestral generations, danger had come always from above, not below.

The very difficulty of observation rendered this mode of research full of excitement, and at the same time made my method of work very simple. Against the sky, green, blue, or black feathers all appear black, and the first two days my glasses helped but little. For several minutes I would watch some tiny bird which might have been a yellow warbler had I been three thousand miles farther north. After memorizing personal characters, scrutinizing its flight and method of feeding, striving to fix its individuality, I would secure the bird, and find in all probability that it was a calliste, or tanager of brilliant plumage. Tomorrow, if I were lucky, I might be able to tell off the numbers of this species, to watch them and to know that I was watching them. But recognition would not be by way of the cerulean or topaz or amethystine hues of plumage, but by the slight idiosyncrasies of flirting tail or wing or of general carriage.

Day by day, as I came to know better the jungle about me, I began to perceive a phase which did not change. Even when the sun shone most brightly, when the coolness of early morning had not yet passed, the mood of the Amazon jungle remained. It was consistent, this low swampy jungle, in its uniform, somber mystery. In spite of wholesale exaggeration it was the dangers which came to mind. Of all places in the world this was probably fullest of life, both in numbers and diversity. Yet it was death—or the danger of death—which seemed in waiting, always just concealed from view.

Beneath my tree I squatted silently. Just overhead the foliage might have been almost northern. The finely cut leaves were like willow, and at one side an oak, unusual but still an oak, reached out a thousand thousand motionless leaves, breaking the glare into innumerable patches. But ahead, the terrible interlacing of vines and thorny ropes, the strangle-hold of serpentine lianas on every available trunk—all this could be only tropic.

The ground glistened here and there with a film of black water which revealed the swamp. Everywhere the mold and leaves of a hundred years lay scattered, the last fallen still green. Many feet above, great fans dangled, rayed fronds dry and crackling, fallen from high overhead, and suspended, waiting for the interfering twigs and foliage to die in turn and permit them to seek dissolution in the mold.

The jungle was bright with flowers, but it was a sinister brightness—a poisonous, threatening flash of pigment, set off by the blackness of the shadows. Heliconia spikes gleamed like fixed scarlet lightning, zigzagging through the pungent air. Now and then a bunch of pleasing, warm-hued berries reminded one of innocuous currants, but a second glance showed them ripening into swollen, liver-hued globes which offered no temptation to taste. One tree dangled hideous purple cups filled with vermilion fruits, and not far away the color sequence was reversed. A low-growing, pleasant-leaved plant lifted bursting masses of purple-black, all dripping like wounds upon the foliage below. Many flowers were unrecognizable save by their fragrance and naked stamens, advertised neither by color nor form of blossom. I despaired of flowers worthy of the name, until close by my foot I saw a tiny plant with a comely, sweet-scented blossom, grateful to the eye and beautiful as our northern blooms are beautiful. The leaf was like scores lying about, and I realized that this was a sproutling of the giant tree. Nothing but the death of this monster could give the light and air which the little plant needed. It was doomed, but it had performed its destiny. It had hinted that much of the beauty of the jungle lay far above the mold and stagnant water. And then I remembered the orchids high overhead. And the realization came that the low-growing blooms needed their glaring colors to outshine the dim, shadowy under-jungle, and their nauseous fumes to outscent the musky vapors of decay.

The plants of the jungle won success either by elbowing their neighbors and fighting their path up to sunlight, or else by adapting their needs to the starvation meed of air and light allotted to the lowly growths. The big-leaved churacas had found another means of existence. They lived like permanent rockets, bursting in mid-air. A long, curved stem shot up and reached far out into space. It was so slender as to be almost invisible in the dim light. At its tip radiated a great burst of foliage, leaves springing out in all directions, and absorbing nutrition which a sapling growing amid the undergrowth could not possibly do.

From daybreak to dark the canella tree was seldom deserted. Usually a score or more birds fluttered and fed among its branches, and true to tropic laws, there were comparatively few individuals but a multitude of species. In the few hours I was able to devote to its study, I identified seventy-six different kinds, and together with those which I saw but could not name, I judge that more than a hundred species must have come to the berries during that week in early May. The first day I secured sixteen specimens, all different; and the following day yielded fourteen more, only one of which was a duplicate of the first day's results.

The bird visitors to the tree arrived in one of two characteristic ways. Many came direct and swiftly, singly or in pairs, flying straight and with decision. These came from a distance, with full knowledge of the berries. They fed quietly, and when satiated flew off. The second method of arrival was wholly casual,—loose flocks drifting slowly from the neighboring jungle, sifting into the tree, and feeding for a time before passing on. When these left it was rather hastily, and in answer to the chirps and calls of the members of their flock who had not been beguiled by the berries and hence had forged steadily ahead.

These more or less well-defined flocks are very characteristic of all tropical jungles. Little assemblages of flycatchers, callistes, tanagers, antbirds, manakins, woodhewers, and woodpeckers are drawn together by some intangible but very social instinct. Day after day they unite in these fragile fraternities which drift along, gleaning from leaves, flowers, branches, trunks, or ground, each bird according to its structure and way of life. They are so held together by an intangible gregarious instinct that day after day the same heterogeneous flock may be observed, identifiable by peculiarities of one or several of its members. The only recognizable bond is vocal—a constant low calling; half unconscious, absent-minded little signals which keep the members in touch with one another, spurring on the laggards, retarding the overswift.

While I watched, there came to my tree a single species of pigeon, two hawks, and two parrots, four hummingbirds, and an equal number of toucans and woodpeckers. The remaining fifty-nine were all passerine birds, of which there were eight each of the families of flycatchers, manakins, and cotingas. Eleven were tanagers.

The greedy, noisy parrakeets were always the center of commotion, wasting more berries than they ate. The toucans, those bizarre birds of whose lives we know so little, yelped and called and bathed in the water caught in the stubs of branches, and fed to repletion. All the flycatchers forgot their usual diet and took to berrying as ardently as the tanagers themselves. Not all the birds came to feed on the berries. A wren hunted insects among the branches, and a hawk found a giant snail crawling up the trunk and devoured it. The insect-eaters of the trunk numbered nine and showed no interest in the berries. Two were woodpeckers and seven woodhewers.

These latter are a strange tropical family four hundred strong, and all the very essence of protective coloring. Their habits of life make of them wandering bits of bark, easy to detect when they are in motion, but vanishing utterly when they are quiet. Their similarity in dress is remarkable. They may be large or small, short or long-tailed, with beaks blunt, sharp, straight, curved, thick, or needle-pointed. In these characters they differ; by these points they must know one another. But their colors are almost identical. Their olives or browns invariably warm into rich foxy rufous on wings and tail, while over head and shoulders a shower of light streaks has fallen, bits of sunlight fixed in down.

Further details belong to the literature of ornithology. But the colors of the berry-hunters—these baffle description, yet we cannot pass them by in silence. The blood and orange splashed on black of the toucans, the scarlet and yellow of woodpeckers, the soft greens and buffs of flycatchers, all these paled when a flock of manakins or tanagers or honey-creepers came to the tree. Every precious stone found its counterpart in the metallic hues of these exquisite feathered folk.

The glory of all was the opal-crowned manakin, a midget in green coat and sulphur waistcoat, with a cap of scaly, iridescent, silvery mother-of-pearl plates, in no way akin to feathers. Until now the life of this Hop o' my Thumb, like those of all his ancestors, had gone smoothly on, with never a human to admire, to wonder, and vainly to echo the question of the great black frog, Wh—y?

On the last day of my stay I walked slowly up the trail toward the canella do matto. For the last time I strained upward at the well-known branches, and with the very movement there came the voice of the swamp. Its tone was insistent, with a tinge of accusation, a note of censure. Wh—y? and after a little time, Wh—y?

I looked about me despairingly. What had I learned after all? Was there any clearing up of the mystery of the jungle? Had my week of scrutiny brought me any closer to the real intimacies of evolution? Or—evading these questions for the time—was there nothing I could do in the few precious moments left?

In five minutes I should turn my back on all this wildness, this jungle seething with profound truths, and great solutions within arm's reach. I should pass to the ocean where monotony compels introspection, and finally to the great center of civilization where the veneer covers up all truths.

Even if my studies had taught only the lesson of the tremendous insurgence of life, could I not emphasize this, make it a more compelling factor to be considered in future efforts toward the frog's question and mine?

My eyes left the foliage overhead and sought the ground. Acting on impulse, I brought from my camping stores an empty war-bag, and scraped together an armful of leaves, sticks, moss, earth, mold of all sorts. Four square feet of jungle dÉbris went into my bag, and I shouldered it.

Then I said adieu to my trail and my tree—a sorrowful leave-taking, as is always my misfortune. For the bonds which bind me to a place or a person are not easily broken. And, as usual when the trail passed from view, the ideal alone remained. The thoughts of mosquitoes, of drenchings, of hours of breathless disappointed waiting, all sank in the memory of the daily discoveries, the mental delights of new research.

A week later, when the sky-line was unbroken by land, when a long ground-swell waved but did not disturb the deep blue of the open sea, I unlaced my bag of jungle mold. Armed with forceps, lens, and vials I began my search. For days I had gazed upward; now my scrutiny was directed downward. With binoculars I had scanned without ceasing the myriad leaves of a great tree; now with lens or naked eye I sought for life or motion on single fallen leaves and dead twigs. When I studied the life of the great tree I was in the land of Brobdingnag; now I was verily a Gulliver in Lilliput. The cosmos in my war-bag teemed with mystery as deep and as inviting as any in the jungle itself.

When I began work I knew little of what I should find. My vague thoughts visualized ants and worms, and especially I anticipated unearthing myriads of the unpleasant "mucuims" or bÊtes rouges, whose hosts had done all in their power to make life in the jungle unhappy.

Day by day my vials increased. Scores of creatures evaded my search; many others, of whose kind I had captured a generous number, I allowed to escape.

My lilliputian census was far from the mere aggregation of ants and worms which I had anticipated, and a review of the whole showed that hardly any great group of living creatures was unrepresented.

As hinting of the presence of wild animals, a bunch of rufous hairs had in some way been tweaked from a passing agouti. Man himself was represented in the shape of two wads which had dropped from my gun-shots some time during the week. One had already begun to disintegrate and sheltered half a dozen diminutive creatures. Five feathers were the indications of birds, two of which were brilliant green plumes from a calliste. Of reptiles there was a broken skull of some lizard, long since dead, and the eggshell of a lizardling which had hatched and gone forth upon his mission into the jungle. A third reptilian trace may have been his nemesis—a bit of shed snake-skin. The group of amphibians was present even in this square of four feet—a very tiny, dried, black, and wholly unrecognizable little frog. Fishes were absent, though from my knees as I scraped up the dÉbris, I could almost have seen a little igarapÉ in which dwelt scores of minnows.

As I delved deeper and examined the mold more carefully for the diminutive inhabitants, I found that this thin film from the floor of the jungle appeared to have several layers, each with its particular fauna. The upper layer was composed of recently fallen leaves, nuts, seeds, and twigs, dry and quite fresh. Here were colonies of small ants and huge, solitary ones; here lived in hiding small moths and beetles and bugs, awaiting dusk to fly forth through the jungle. The middle layer was by far the most important, and in it lived four fifths of all the small folk. The lowest layer was one of matted roots and clayey soil and its animal life was meager.

Between the upper and the middle strata were sprouting nuts and seeds, with their blanched roots threaded downward into the rich dark mold, and the greening cotyledons curling upward toward light and warmth. Thus had the great bird-filled canella begun its life. In my war-bag were a score of potential forest giants doomed to death in the salt ocean. But for my efforts toward the Wh—y, their fate might have been very different.

Some of the half-decayed leaves were very beautiful. Vistas of pale, bleached fungus lace trailed over the rich mahogany-colored tissues, studded here and there with bits of glistening, transparent quartz. Here I had many hints of a world of life beyond the power of the unaided eye. And here too the grosser fauna scrambled, hopped, or wriggled. Everywhere were tiny chrysalides and cocoons, many empty. Now and then a plaque of eggs, almost microscopic, showed veriest pin-pricks where still more minute parasites had made their escape. When one contracted the field of vision to this world where leaves were fields and fungi loomed as forests, competition, the tragedies, the mystery lessened not at all. Minute seeds mimicked small beetles in shape and in exquisite tracery of patterns. Bits of bark simulated insects, a patch of fungus seemed a worm, while the mites themselves were invisible until they moved. Here and there I discovered a lifeless boulder of emerald or turquoise—the metallic cuirass of some long-dead beetle.

Some of the scenes which appeared as I picked over the mold, suddenly unfolding after an upheaval of dÉbris, were like Aladdin's cave. Close to the eye appeared great logs and branches protruding in confusion from a heaped up bank of diamonds. Brown, yellow, orange, and white colors played over the scene; and now over a steep hill came a horrid, ungainly creature, with enormous proboscis, eight legs, and a shining, liver-colored body, spotted with a sickly hue of yellow. It was studded with short, stiff, horny hairs—a mite by name, but under the lens a terrible monster. I put some of these on my arm, to see if they were the notorious "mucuims" which tortured us daily. Under the lens I saw the hideous creature stop in its awkward progress, and as it prepared to sink its proboscis I involuntarily flinched, so fearful a thing seemed about to happen.

The lesser organisms defy description. They are nameless except in the lists of specialists, and indeed most are of new, quite unnamed forms. The only social insects were small twigfuls of ant and termite colonies, with from five to fifteen members. All others were isolated, scattered. Life here, so far beneath the sunlight, is an individual thing. Flocks and herds are unknown; the mob has no place here. Each tiny organism must live its life and meet its fate single-handed.

Little pseudo-scorpions were very abundant, and I could have vialed hundreds. They rushed out excitedly and, unlike all the other little beings, did not seek to hide. Instead, when they were disturbed, they sought open spaces, walking slowly and brandishing and feeling ahead with their great pincer-tipped arms, as long as their entire body. When irritated or frightened, they scurried backwards, holding up their chelÆ in readiness.

Mites were the most abundant creatures, equaling the ants in number, always crawling slowly along, tumbling over every obstacle in their path and feeling their way awkwardly. Their kinds were numerous, all villainous in appearance. Ticks were less common but equally repellent. Small spiders and beetles were occasionally found, and hundred-legged wrigglers fled to shelter at every turn of a leaf. The smallest snails in the world crawled slowly about, some flat-shelled, others turreted. Tiny earthworms, bright red and very active, crept slowly through fungus jungles until disturbed, when they became an amazingly active tangle of twisting curves, dancing all about. Simple insects, which we shall have to call collembolas, were difficult to capture. They leaped with agility many times their own length, and when quiescent looked like bits of fungus. As for the rest, only Adam and a few specialists hidden in museums could call them by name. They were a numerous company, some ornamented with weird horns and fringes and patterns, others long of legs or legless, swift of foot or curling up into minute balls of animate matter.

One thing was evident early in my exploration: I was in a world of little people. No large insects were in any of the dÉbris. The largest would be very small in comparison with a May beetle. And another thing was the durability of chitin. The remains of beetles, considering the rareness of living ones, were remarkable. The hard wing-cases, the thorax armor, the segments of wasps, eyeless head masks, still remained perfect in shape and vivid in color. Even in the deepest layers where all else had disintegrated and returned to the elements, these shards of death were as new.

And the smell of the mold, keen and strong as it came to my nostrils an inch away—it was pungent, rich, woody. It hinted of the age-old dissolution, century after century, which had been going on. Leaves had fallen, not in a sudden autumnal downpour, but in a never-ending drift, day after day, month after month. With a daily rain for moisture, with a temperature of three figures, for the quicker increase of bacteria, and an excess of humidity to foster quick decay, the jungle floor was indeed a laboratory of vital work—where only analytic chemistry was allowed full sway, and the mystery of synthetic life was ever handicapped, and ever a mystery.

Before the vessel docked I had completed my task and had secured over five hundred creatures of this lesser cosmos. At least twice as many remained, but when I made my calculations I estimated that the mold had sheltered only a thousand organisms plainly visible to the eye.

And when I had corked my last vial and the steward had removed the last pile of shredded dÉbris, I leaned back and thought of the thousand creatures in my scant four square feet of mold. Then there came to mind a square mile of jungle floor with its thin layer of fallen leaves sheltering more than six billion creatures. Then I recalled the three thousand straight miles of jungle which had lain west of me, and the hundreds of miles of wonderful unbroken forest north and south, and my mind became a blank. And then from the mist of unnamable numerals, from this uncharted arithmetical census, there came to memory a voice, deep and guttural,—and this time the slow enunciation was jeering, hopeless of answer, Wh—y? And soon afterwards, Wh—y? And I packed up my last box of vials and went on deck to watch the sunset.