Eye Spy Part 9

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 brus.h.!.+ 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 cl.u.s.ter of mignonette-scented blossoms. Thus they follow down towards the tip of the branch, where the cl.u.s.ters suddenly cease, and are replaced by long, slender, curving and branched tendrils, sometimes ten inches long. We might thus reasonably a.s.sume the tendril in this case to be a modified blossom cl.u.s.ter, but there is no need for us ever to a.s.sume 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 cl.u.s.ter 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 pa.s.sion-flower and plants of the melon family, notably the wild star-cuc.u.mber, 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 pa.s.sion-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 a.s.sociates 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 Gra.s.shopper

A few days ago, while returning from a walk, I chanced to observe a dead gra.s.shopper 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 s.p.a.ce 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 compa.s.sionately 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 "mola.s.ses" 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 coc.o.o.n, filled with hopes of a beautiful b.u.t.terfly 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" ent.i.tled "Among Our Footprints." I wished to describe and ill.u.s.trate 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 gra.s.shopper to complete my drawing. Directly in front of my city house a number of vacant gra.s.sy 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, 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 ill.u.s.tration to the article on "Footprints" as "the ungainly victim,"

I little dreaming when I gave him such a t.i.tle 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 gra.s.shopper 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 gra.s.shopper 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 gra.s.shopper's interior, so gla.s.sy 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 astonis.h.i.+ng 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 s.p.a.ce of time from the activity of the gra.s.shopper 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, gla.s.sy sh.e.l.l, now more gla.s.sy 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 cla.s.sification 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 peac.o.c.k'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 a.s.sured 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.

[Ill.u.s.tration: A]

[Ill.u.s.tration: B]

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.

[Ill.u.s.tration: C]

[Ill.u.s.tration: D]

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 astonis.h.i.+ng 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 b.u.t.terflies, 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 cl.u.s.ter 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 cl.u.s.ter 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.

In order to make it clear I have drawn a progressive series of pictures which hardly require description. The flowers are visited by small bees, b.u.t.terflies, and other insects. At the left is an insect just alighting on a clump of the blossoms of the high-anther form indicated below it. The black probe represents the insect's tongue, which, as it seeks the nectar at the bottom of the tube, gets dusted at its thickened top with the pollen from the anthers. We next see the insect flying away, the probe beneath indicating the condition of its tongue. It next alights on clump No. 2, in which the flowers happen to be of the high-stigma form, as shown below. The tongue now being inserted, brings the pollen against the high stigma, and fertilizes the flower, while at the same time its tip comes in contact with the low anthers, and gets pollen from them. We next see the insect flying to clump No. 3, the condition of its tongue being shown below. Clump No. 3 happens to be of the first low-stigma form of flowers, and as the tongue is inserted the pollen at its tip is carried directly to the low stigma, and _this_ flower is fertilized from the pollen from the anthers on the same level in the previous flower. And thus the riddle is solved by the insect. From clump to clump he flies, and through his help each one of the pale blue blooms is sure to get its food, each flower fertilized by the pollen of another.

[Ill.u.s.tration: 1st Clump.--Flower enlarged. Insect's Tongue inserted.

Pollen high on Insect's Tongue after withdrawal from Blossom.

2d Clump.--Flower enlarged. Pollen thrust against high Stigma at top and touching Pollen below.

Pollen at Base of Insect's Tongue after withdrawal from Blossom.

3d Clump.--Flower enlarged. Pollen thrust against low Stigma.]

Another beautiful provision is seen in the difference in size of the pollen-grain of the two flowers, those of the high anthers being much larger than those from the lower anthers. These larger grains are intended for the high stigma, which they are sure of reaching, while those of smaller size, on the top of the tongue, which should happen to be wiped off on the high stigma, are too small to be effective for fertilization.

Luck In Clovers

Under one guise or another the fickle G.o.ddess Fortuna would seem to have established her infallible interpreters or mediators. The lovelorn maiden with the daisy, its petals falling beneath her questioning finger-tips to the alternate refrain, "He loves me. He loves me not," is a sacrificial episode in the life of the daisy wherever it grows.