Part 14

It is soon perfectly plain that the stem is a modified root. For instance, plants have been taken up from the sod and replaced in the ground upsidedown, the roots subsequently becoming stems, and bearing leaves, and the buried leafy stems assuming the functions of roots. Leaves are mere modified branches, and the flowers modified leaves. Pistils and stamens in flowers are modified petals, or rather petals are modified stamens, the "doubling" of flowers representing the being thus accomplished, while the petals again are mere changed leaves. A neighbor of mine has a bush bearing green roses--all leaves. In the water-lily you will find it difficult to determine just where the stamen ends and the petals begin, so gradual is the blending. In the peony the same is true, and carried still further in the merging of petals and calyx into the approximate leaves.

And so it is with tendrils. In certain plants the point of the leaf, through ages of "natural selection," has gradually been prolonged into a slender arm, which clasps the branches of trees, and enables the plant thus endowed to climb higher to sun and sky, and thus to thrive more vigorously than its less fortunate brothers. The plant so advantageously equipped transmits its tendency to its offspring, and has therefore survived in place of its ancient fellows, and is the type perpetuated or "selected" by nature. Such a tendril, then, is a modified leaf. How is it in the pea? Here we find four leaflets in two opposite pairs, but no odd leaflet at the end of the main stalk, such as we see in almost all other plants of its family. But in place of this leaflet we find a branching tendril reaching out on all sides for conquest. How quietly by the aid of these eager arms the sweet-pea climbs to the top of its brush! In the common catbrier or smilax we see two slender thread-like tendrils growing from the base of each leaf. Here we have another modification, a development of the "stipule," that tiny pointed growth common to many leaves, and particularly notable at the base of a rose leaf. Still another plan has been evolved in the grape-vine. If we examine our grape arbor in June we find a number of drooping, swaying branches. The leaves are scattered singly at intervals of a few inches along the branch, each of the upper ones being attended on its opposite side by a drooping cluster of mignonette-scented blossoms. Thus they follow down towards the tip of the branch, where the clusters suddenly cease, and are replaced by long, slender, curving and branched tendrils, sometimes ten inches long. We might thus reasonably assume the tendril in this case to be a modified blossom cluster, but there is no need for us ever to assume such a thing. If we will only search with sufficient care we shall at last discover the absolute proof of the fact in a tendril which is partly in blossom, the nearest leaf-joint above it having a full cluster of blossoms, and the tendril below it, nearer the tip, not a few scattered flower-buds at its tips. This grape-vine instance may be taken as a demonstration that in no case is the tendril a special or primal organ, but merely an old one adapted to a new purpose. In one instance from a leaf, in another from a flower-stalk, just which can generally be determined by a sufficient search for the telltale intermediate form somewhere to be found on the plant.

Among the most beautiful of all tendrils are those of the passion-flower and plants of the melon family, notably the wild star-cucumber, whose portrait is here presented. It is a more or less common weed, to be found about gardens and barn-yards, where it covers the fences with its profuse, clambering growth, its stalks everywhere entangled or drawn close to support by their long, green, spiral springs, and its free, branching, young tendril tips reaching out in all directions for fresh foothold, and in its absence content at length with a friendly intertwining among themselves, and a consequent tangle of green convolutions. It is hard to believe that these long, outreaching arms at the summit of this vine are identical with the closely twisted spirals below, but such is the case; let any one of them once feel the contact of even the frailest support of twig or stalk, and it is soon close in the embrace of its eager tip, and the contraction of the spring commences, but the method of this contraction is worth our study.

In order for this tendril to coil it must twist, and it is perfectly plain on general principles that with both ends held fast twisting is impossible. But this little paradox is evidently dismissed by the tendril. If we tie a short string between two given points, and attempt to twist it with our finger and thumb, we succeed in turning the string, 'tis true, but the twist on the right side neutralizes that on the left, being in the opposite direction. In this way only can the cord be twisted. If we twist with sufficient patience we may imitate the coil of the tendril, which is performed precisely in this way. Herein lies the secret of that little loop or kink in the centre of all tendrils--a given point, which cannot be determined on the extended tendril, but whose mission is to reverse the twist in opposite directions as soon as the tip has secured its contact, and thus permit the coiling process to proceed. In tendrils of exceeding length several of these reverse loops may be found at regular intervals, sometimes as many as six in a single tendril, but the coiling process usually awaits this contact. Unsatisfied tendrils of the grape, for instance, will remain unchanged through the entire season, or until their sensitive touch has been lost. Others, like those of the passion-flower, will occasionally become discouraged and curl up all by themselves, in which case, the other tip being free, the curl is perfect and continuous and without the reverse loop, which is now unnecessary. But the function of the tendril is to clasp and hold. Its growth is not complete until thus quickened by the new responsibility. Tendrils on duty become tough and sinewy in comparison to their idling neighbors. How firm and rigid are these swollen coils upon the grape-vine!

We do not gather "figs from thistles," but some equally incongruous botanical associates are sometimes brought about through the insinuating and clambering methods of the tendril. Have we not all seen apple-trees bearing pumpkins or squashes or gourds, all originally carried thither in the form of great yellow blossoms or tender shoots! The grape-vine occasionally plays a singular botanical prank in the orchard. Here is a drooping tendril which has been swinging about for weeks from its vine canopy on the old apple-tree. It had become almost discouraged, when a chance-favoring breeze wafted its tip in contact with an apple close by. It was its last chance; with its hooked extremity it clasped the stem of the fruit, and soon made itself fast with three or four firm coils. Doubtless the little reversing loop somewhere along the tendril was also awakened from its chronic lethargy, and did its best to start the coil. Presumably it succeeded, for the pull was sufficient to dislodge the apple, which, falling to the entire length of the tendril, was still held fast in the grip, whose new responsibility had given it new strength.

And there our apple hung for weeks, swinging like a pendulum from the slender grape-vine, the coils on duty still keeping their firm grip on the stem, even though all above were straightened by the weight of the burden.

A Strange Story of a Grasshopper

A few days ago, while returning from a walk, I chanced to observe a dead grasshopper upon the dirt at the side of the road. Now this incident would not have been of special importance had I not discovered, upon careful post-mortem examination, the very remarkable manner of the insect's death, which recalled a similar surprising episode of several years ago which I had almost forgotten. Upon referring to my note-book of that period, however, I found considerable space devoted to the incident, which greatly astonished me at the time. Inasmuch as it presents in a startling light the wonderful and strange resources by which nature holds in check the too rapid increase of species and maintains the great law of equilibrium among the insect forces, it is well worth recalling in these pages, in the firm belief that my young entomological readers will henceforth look more compassionately and tenderly upon the poor "high-elbowed grig" who is the unfortunate hero of my story. He is familiar to us all, that hovering "rattler" above the hot, dusty road of August, flying up from nowhere beneath our feet in the path, fluttering like a yellow moth, and always disappearing before our eyes when he alights. He is also known as the "Quaker," from his drab suit and bonnet, and his generosity with his "molasses" is proverbial from the days of the Pilgrim settlers. Who would have believed that such a fate as the following lay in store for him.

In previous papers I have indicated some of the remarkable pranks which the various ichneumon-flies play with unsuspecting caterpillars. The polyphemus, for instance, whose cocoon, filled with hopes of a beautiful butterfly existence, yields only a swarm of wasps. The caterpillars are helpless, and would seem an easy prey to the wily fly who lays her eggs upon them; but even the agile-winged "Quaker," and doubtless many of his kind--yes, and still more agile insects--are not quick enough to escape a like fate.

At the time of my discovery I had in preparation an article for "Harper's Magazine" entitled "Among Our Footprints." I wished to describe and illustrate a singular battle which I had shortly before observed between a large red mutilla ant and a "Quaker." The mutilla I had captured at the time, and had preserved as a specimen. I needed only the grasshopper to complete my drawing. Directly in front of my city house a number of vacant grassy lots offered a favorite haunt for the insects--I used to call it the Quaker camp-meeting ground--and I started out to procure one. Having no net, I was soon convinced that I was greatly at a disadvantage. The thermometer was about 90 deg., and, of course, the "Quakers," being in their element, had much the best, not to say the easiest, time of it. I at length gave up the chase, and was about leaving the field, when fortune favored me by the discovery of a clumsy specimen, which seemed unable to fly for any great length, and he was soon captured. Upon examination his wings seemed partially paralyzed, but otherwise he appeared to be in good health and spirits, his hind legs being especially lively and snappy. I immediately took the insect to my studio, and pinned him through the thorax. He was strong enough to pull out the pin from the board and jump around the room with it in my temporary absence.

I lost no time in taking his portrait, which figured in the illustration to the article on "Footprints" as "the ungainly victim," I little dreaming when I gave him such a title what a remarkable sort of victim he even then was. The drawing took me about ten minutes. I then left the studio, and was absent precisely fifteen minutes. Upon returning I found the grasshopper dead.

My curiosity was aroused, not only by such a rapid demise (for the impaling through the thorax is not usually an immediately fatal injury to an insect), but especially by some very strange and unnatural automatic movements of the victim--head protruding and turning from side to side; queer expansion of body, as though breathing; unusual lifting and other motions of legs, particularly of hind legs; the whole demonstration a mockery on life. The grasshopper was pinned to my drawing-board, and against a piece of newspaper. As I watched his strange antics, I suddenly discovered that he had become a veritable phantom of his former self; that I could actually read the newspaper text through his body. Examination now revealed the mystery. I could easily see every nook and cranny of the grasshopper's interior, so glassy were the walls of the body, and I could now count about a dozen small, white larvae, which were now full grown, and were crawling about within through head, thorax, body, and hind legs, cleaning its walls of every particle of remaining tissue, and causing the singular motions described. Such a strange house-cleaning I never saw before.

When the "Quaker" locust was captured it showed not the slightest sign of any such goings-on within its being. The final voracity of the larvae was swift and terrible. And what an astonishing instinct is that which should teach these parasites to avoid the vitals of their insect host until the last moments of their own final, complete growth! The entire space of time from the activity of the grasshopper to the empty, transparent phantom was less than thirty minutes. I placed the unfortunate victim in a small, close box. Next morning he presented nothing but a clean, glassy shell, now more glassy than before, empty of every vestige of organic matter, while scattered about on the bottom of the box lay fifteen dark red, egg-shaped chrysalides of the escaped larvae. Two weeks later, upon opening the box, a swarm of flies flew out. I was enabled to keep two of them. They were almost exactly like the common house-fly to the ordinary observer, but belonged to a distinct genus. At this writing, in the absence of my specimen, I cannot give the name by which they are known in learned circles, but I think I am safe in saying that they probably belong to the group called Tachina, a family of parasitic flies which spend their early lives in a similar questionable manner, to the probable discomfort of potato-bugs, caterpillars, and other accommodating insect hosts.

I had seen similar flies emerging from my caterpillar boxes in my early entomological days without suspecting their significance, and any large collection of caterpillars in confinement is likely to include a victim.

Riddles in Flowers

Indeed, are they not all riddles? Where is the flower which even to the most devoted of us has yet confided all its mysteries? In comparison with the insight of the earlier botanists, we have surely come much closer to the flowers, and they have imparted many of their secrets to us. Through the inspired vision of Sprengel, Darwin, and their followers we have learned something of their meaning, in addition to the knowledge of their structure, which comprised the end and aim of the study of those early scholars, Linnaeus, Lindley, Jussieu, and De Candolle. To these and other eminent worthies in botany we owe much of our knowledge of how the flowers are made, and of the classification based upon this structure, but if these great savants had been asked, "You have shown us that it is so, but why is it thus?" they could only have replied, "We know not; we only know that an all-wise Providence has so ordained and created it."

Take this little collection, which I have here presented, of stamens and petals selected at random from common blossoms. What inexplicable riddles to the botanist of a hundred years ago, even of sixty years ago! For not until that time was their significance fully understood; and yet each of these presents but one of several equally puzzling features in the same flowers from which they were taken.

In that first anther, for example, why those pores at the tip of the cells, instead of the usual slits at the sides, and why that pair of horns at the back? And the next one, with longer tubes, and the same two horns besides! Then there is that queer specimen with flapping ears--one of six from the barberry blossom; and the pointed, arrow-headed individual with a long plume from its apex; and the curved C-shaped specimen--one of a pair of twins which hide beneath the hood of the sage blossom. The lily anther, which comes last, is poised in the centre. Why? What puzzles to the mere botanist! for it is because these eminent scholars were mere botanists--students and chroniclers of the structural facts of flowers--that this revelation of the truth about these blossom features was withheld from them. It was not until they had become philosophers and true seers, not until they sought the divine significance, the reason, which lay behind or beneath these facts, that the flowers disclosed their mysteries to them.

Look at that random row of petals, too!--one with a peacock's eye, two others with dark spots, and next the queer-fingered petal of the mignonette, followed by one of that queer couple of the monk's-hood blossom which no one ever sees unless he tears the flower hood to pieces. We all know the nasturtium, but have we thought to ask it why these petals have such a deep crimson or orange colored spot, and why each one is so beautifully fringed at the edge of its stalk?

These are but a dozen of the millions of similar challenges, riddles, puzzles, which the commonest flowers of field and garden present to us; and yet we claim to "know" our nasturtium, our pink, our monk's-hood larkspur, our daisy, and violet!

No; we must be more than "botanists" before we can hope to understand the flowers, with their endless, infinite variety of form, color, and fragrance.

It was not until the flowers were studied in connection with the insects which visit them that the true secret of these puzzling features became suspected.

We all know, or should know, that the anther in flowers secretes and releases the pollen. For years even the utility of this pollen was a mystery. Not until the year 1682 was its purpose guessed, when Nehemias Grew, an English botanist, discovered that unless its grains reached the stigma in the flower no seed would be produced (Diagram A). But the people refused to believe this, and it was not until fifty years later that Grew's statement was fully accepted, and then only because the great Linnaeus assured the world that it was true. But about fifty years later another botanist in Germany, Sprengel, made the discovery that the flower could not be fertilized as these botanists had claimed, that in many blossoms the pollen could not fall on the stigma.

Sprengel knew that this pollen must reach the stigma, but showed that in most flowers it could not do so by itself. He saw that insects were always working in the flowers, and that their hairy bodies were generally covered with pollen, and in this way pollen grains were continually carried to the stigma, as they could easily be in these two blossoms shown at Diagram B. Sprengel then announced to the world his theory--the dawn of discovery, the beginning of the solution of all these floral riddles. The insect explained it all. The bright colors and fragrance were intended to attract him, and the nectar to reward him, and while thus sipping he conveyed the pollen to the stigma and fertilized the flower.

But now Sprengel himself was met with most discouraging opposition to his theory, showing that he had guessed but half the secret after all. Flowers by the hundreds were brought to his notice, like that shown in Diagram C, in which the insect could not transfer the pollen from anther to stigma, as the stigma is closed when the pollen is ripe, and like that in Diagram D, which does not open until the pollen is shed. For seventy years this astonishing fact puzzled the world, and was at last solved by the great Darwin, who showed that nearly all flowers shun their own pollen, and are so constructed, by thousands of singular devices, that the insect shall bring to each the pollen of another flower of the same species, and thus effect what is known as cross-fertilization.

We must then look at all flowers as expressions of welcome to some insect--day-flowering blossoms mostly to bees and butterflies, and night-bloomers to moths. And not only expressions of welcome, but each with some perfect little plan of its own to make this insect guest the bearer of its pollen to the stigma of another flower of the same species. And how endless are the plans and devices to insure this beautiful scheme! Some flowers make it certain by keeping the stigma closed tight until all its pollen is shed; others place the anther so far away from the stigma as to make pollen contact impossible; others actually imprison these pollen-bringing insects until they can send them away with fresh pollen all over their bodies.

Take almost any flower we chance to meet, and it will show us a mystery of form which the insect alone can explain.

Here is one, growing just outside my door--a blossom "known" even to every child, and certainly to every reader of the "Round Table"--the pretty bluets, or Houstonia, whose galaxy of white or blue stars tints whole spring meadows like a light snowfall. We have "known" it all our lives. Perhaps we may have chanced to observe that the flowers are not all constructed alike, but the chances are that we have seen them all our lives without discovering this fact. If we pluck a few from this dense cluster beside the path, we observe that the throat of each is swollen larger than the tube beneath, and is almost closed by four tiny yellow anthers (Fig. 1). The next and the next clump may show us similar flowers; but after a little search we are sure of finding a cluster in which a new form appears, as shown in Fig. 2, in which the anthers at the opening are missing, and their place supplied with a little forked stigma! The tube below is larger than the first flower for about two-thirds its length, when it suddenly contracts, and if we cut it open we find the four anthers secreted near the wide base of the tube. What does it mean, this riddle of the bluets? For hundreds of years it puzzled the early botanists, only finally to be solved by Darwin. This is simply the little plan which the Houstonia has perfected to insure its cross-fertilization by an insect, to compel an insect to carry its pollen from one flower and deposit it upon the stigma of another. Once realizing this as the secret, we can readily see how perfectly the intention is fulfilled.