by Grant Allen
Now, it may sound odd at first hearing when I tell you that what the animals thus do, the plants do also. “What?” you will say. “A plant move bodily from the surface of the water and bury itself in the mud! It seems almost incredible.” But the accompanying illustrations of one such plant, the curled pond-weed, will show you that the aquatic weeds take just as good care of themselves against winter cold as the aquatic animals.
In No. 3 you see a shoot of curled pond-weed preparing to receive cold attacks at the approach of autumn. You may perhaps have noticed for yourself that almost all plants of stagnant waters tend to be freshest and most vigorous at the growing end — the upper portion; while the lower and older part is usually more or less eaten away by browsing water beasties, or incrusted by parasites, or draggled and torn, or water-logged and mud-smeared
The really vital part of the plant at each moment is, as a rule, the top or growing shoot. Now, if the curled pond-weed were to let itself get overtaken bodily by winter, and its top branches or vigorous shoots frozen in the crust of ice which must soon coat the pond, it would be all up with it. To guard against this calamity, therefore, the plant has hit upon a dodge as clever in its way as that of our old friend the soldanella, which laid by fuel to melt the glacier ice in the Alpine springtide. Prevention, says the curled pond-weed, is better than cure. So, in No. 3, you catch it in the very act of getting ready certain specialised detachable shoots, which are its liveliest parts, and in which all the most active protoplasm and chlorophyll (or living greenstuff of the plant) are collected and laid by, much as food is laid by in the bulb of a hyacinth or in the tuber of a dahlia. These shoots are, as it were, leafy bulbs, meant to carry the life of the plant across the gulf of winter.
In No. 4 we come upon the next act in this curious and interesting vegetable drama. Most people regard plants as mere rooted things, with no will of their own, and no power of movement. In reality, plants, though usually more or less attached to the soil, have almost as many tricks and manners of their own as the vast mass of animals; they provide in the most ingenious and varied ways for the most diverse emergencies. The winter shoots of the curled pond-weed, for example, carrying with them the hopes of the race for a future season, are deliberately arranged beforehand with a line of least resistance, a point of severance on the stem, at which in the fulness of time they peaceably detach themselves. You can note in the illustration how they have glided off gently from the parent stalk, and are now sinking by their own gravity to the warmer water of the bottom, which practically never freezes in winter. And the reason why they sink is that, being full of rich living greenstuff, they are heavier than the water, and heavier than the stem which previously floated them. This stem has many air cavities to keep it fairly erect and waving in the water: but the winter shoots have none, so that as soon as they detach themselves they sink of their own mere weight to the bottom. You may notice that the leaves of deciduous trees in autumn have similar lines, ordained beforehand, along which they break off clean, so as not to tear or injure the permanent tissues; this is particularly noticeable in the foliage of the horse-chestnut, and also (in spring) in the common aralia, so often grown as a drawing-room decoration.
No. 5 continues the same series, and shows us how the winter shoots, now sunk to the bottom, bore a hole and root themselves in the soft mud by their sharp, awl-like ends; after which they prepare to undergo their sleepy hibernation. They are now essentially detached buds or cuttings, analogous to those which the gardener artificially lops off and “strikes” in our gardens. Only, the gardener’s cuttings have been rudely sliced off with a knife, after the crude human fashion, while those of the pond-weed have been neatly released without injury to the tissues, the separation being performed by an act of growth, with all the beautiful perfection that marks nature’s handicraft.
In the soft slimy mud, the shoots of the curled pond-weed lie by during the frozen period, hearing the noise of the gliding skates above them, and suffering slightly at times from the chill of the water, but actually protected by the great-coat of ice from the severest effects of the hard weather. By-and-by, when spring comes again, however, the shoots begin to bud out, as you see in No. 6, and once more to produce the original type of pond-weed. The weed then continues to form leaves and stems, and finally to flower, which it does with a head or spike of queer little green blossoms, raised unobtrusively above the surface of the water. They are not pretty, because they do not depend upon animals for the transference of their pollen. I could tell you some curious things about these flowers, too, which find themselves far from insects, and destitute of attractive petals; so they have taken in despair to a quaint method of fertilisation by bombardment, so to speak — the stamens opening in calm weather, and dropping their pollen out on the saucer-like petals, whence the first high wind carries it off with a burst to the stigma or sensitive surface of the sister flowers. But that, though enticing, is another story, alien to the philosophy of the pond in winter. I will only add here that the pond-weed does not set its seeds very well, and that chances of dispersal are somewhat infrequent, so that irregular multiplication by these winter shoots has largely taken the place with it of normal multiplication by means of seedlings. At the same time, we must remember that no prudent plant can venture to depend for ever upon such apparent propagation by mere subdivision, which is not really (in any true sense) propagation at all, but is merely increased area of growth for the original parent, split up into many divergent personalities; so that the curled pond-weed takes infinite pains all the same to flower when it can, and to discharge its pollen and disperse its seed as often as practicable. Only by seedlings, indeed (that is to say by fresh blood — truly new individuals), can the vigour of any stock be permanently secured.
Sometimes, again, the entire plant retires to the depths in winter, like the pond-snail. This is the case with that pretty floating aquatic lily, the water-soldier, whose lovely flowers make it a frequent favourite on ornamental waters. In summer it floats; but when winter comes it sinks to the bottom, and there rests on the mud till spring returns again.
In No. 7 you see how another familiar and fascinating denizen of the pond, the little whirligig beetle, provides his winter quarters. The whirligig is one of the daintiest and most amusing of the inhabitants of our ponds. He is a small round beetle, in shape like a grain of corn; but as he is intended to sport and circle on the surface of the water in the broad sunshine, he is clad in glistening mail of iridescent tints, gorgeous with bronze and gold, to charm the eyes of his fastidious partner. You seldom see whirligigs alone; they generally dart about in companies on the surface of some calm little haven in the pond, a dozen at a time, pirouetting in and out with most marvellous gyrations, yet never colliding or interfering with one another. I have often watched them for many minutes together, wondering whether they would not at last get in one another’s way: but no; at each apparent meeting, they glide off in graceful curves, and never touch or graze. They go on through figures more complicated than the Lancers or Sir Roger de Coverley, now advancing, now retreating, always in lines of sinuous beauty, without angularity or strain, and apparently without premeditation; yet never for a second do they interfere with a neighbour’s mazy dance, often as they cross and recross each other’s merry orbits. Dear little playful things they seem, as if they enjoyed existence like young lambs or children. Sociable, alert, for ever gambolling, they treat life as a saraband, but with a wonderfully keen eye for approaching danger. They look at times as if you could catch them without trouble; yet put down your hand, and off they dart at once to the bottom, or elude you by a quick and vigilant side movement, always on the curve, like a good skater or a bicyclist.
This rapid skimming in curves or circles on the surface of the water is produced in a most interesting way by the co-operation of the various pairs of legs, which I can best explain by the analogy of the bicycle. The two shorter and active hind-legs produce the quick forward dart, just as the main motion of the cycle is
given it by the back wheel; the longer front legs act like the front wheel of the cycle in altering the direction; one of them is jerked out to right or left, rudderwise, and gives the desired amount of curve to the resulting motion according to the will and necessities of the insect. The steering of a Canadian canoe comes very near it. Anybody who has sculled or rowed, indeed, knows well the extraordinary ease with which a boat can be shored off instantaneously from another, or the marvellous way in which gliding curves can be produced on the almost unresisting surface of the water. The whirligig beetle has a perfect steering apparatus in his long and extensible fore-legs, and by their means he performs unceasingly his play of merry and intricate evolutions.
When whirligigs are alarmed, however, they dive below the surface as one of a pair is doing in No. 7, and carry down with them a large bubble of air, for breathing purposes, entangled in the joints of their complicated legs and the under parts of their bodies. On this quaint sublacustrine balloon they subsist for breathing till the danger is past and they can come to the top again.
Early in April, when the weather is fine, you begin to see the whirligig beetles dancing in and out in companies, like so many water-fairies, on the still top of the pond. They prefer calm water; when the wind drives little ripples to the eastern end of the pool, you will find them practising their aquatic gymnastics under lee of the shore on the western side; when an east wind ruffles the western border, you will find them gyrating and interlacing, coquetting and pirouetting, by the calmer eastern shallows. As they move in their whirls, they form little transient circles on the water’s top, which spread concentrically; and the mutual interference of these widening waves is almost as interesting at times as the astonishing velocity and certainty of movement in the beetles themselves. So, all summer long, they continue their wild career, seeming to earn their livelihood easily by amusing themselves. But as soon as winter approaches, a change comes o’er the spirit of their dream. They retire to the depths, as you may observe in No. 8, and bury themselves in the mud while the pond is frozen over. During this period they indulge in a good long nap of some five or six months, and, awaking refreshed in April, come to the surface once more, where they begin their gyratory antics all over again, da capo. It is a merry life; and though the whirligig can fly, which he does occasionally, ’tis no wonder he prefers his skimming existence on the still glassy sheet of his native waters.
The two larger British water-beetles, which are such favourite objects in the aquariums of young naturalists, do not lead quite so exclusively aquatic a life; they pass their youth as larvæ in the pond, and they return to it in their full-winged or beetle stage, being most expert divers; but they both retire to dry land to undergo their metamorphosis into a chrysalis, and they spend their time in the pupa-case in a hollow in the ground. Something similar occurs with many other aquatic animals, which are thus conjectured to be the descendants of terrestrial ancestors, whom the struggle for life has forced to embrace the easier opening afforded by the waters.
In this respect, that rather rare and beautiful little water-plant, the frogbit, shown in No. 9, has a life-history not unlike the career of the water-beetles. It is a quaint and pretty herb, which never roots itself in the mud, like the curled pond-weed, but floats freely about on the surface, allowing its long roots to hang down like streamers into the water beneath it. The short stem or stock is submerged; the leaves expand themselves freely and loll on the surface. Like most other floating water-leaves which thus support themselves on the top of the water, they are almost circular in form — a type familiar to all of us in the white and yellow water-lily, and also in the beautiful little fringed limnanthemum. The reason why floating leaves assume this circular shape is easy to perceive; they need no stout stalk to support them; like aërial foliage, the water serving to float them on its surface; and as they find the whole surrounding space free from competition, with no other plants to interfere with them, as in the crowded meadows and hedgerows of the land, they spread freely in the sunshine on every side, drinking in from the air the carbonic acid which is the chief food of plants. In short, the round shape is that which foliage naturally assumes when there is no competition, no architectural or engineering difficulty, plenty of food and plenty of sunshine.
The frogbit as a whole, then, is not submerged like the curled pond-weed; it floats, not rooted, but free. Yet when it comes to flowering, it has to quit the water, just like the great water-beetles, and emerge upon the open air above, so as to expose its flowers to the fertilising insects. These flowers are extremely delicate and beautiful, with three papery white petals, and a yellow centre; they make the plant a real ornament to all the ponds where it fixes its residence. The males and females grow on separate plants, and aquatic flies act as their ambassadors. Such is the summer life of the frogbit, while fair weather lasts; but, like all other pond denizens, it has to reckon in the end with the frozen season.
It does so in a way slightly different from, though analogous to, that of the curled pond-weed. No. 10 shows you the frogbit after the flowering season is over, when it begins to anticipate the approach of winter. It then sends out slender runners, like those of the strawberry vine, on the end of each of which is formed a winter bud, which answers to the winter shoots of the curled pond-weed. By-and-by the pond will freeze, and the floating leaves of the frogbit will be frozen and killed with it. But the prudent plant provides for its own survival in the person of its offshoots, which are not its young, but integral parts of its own individuality. It fills them with starch and other rich foodstuff for growth next season. About the time when the pond grows cool, the buds detach themselves, like the winter shoots of the pond-weed, and slowly descend by their own weight to the bottom. But they do not root themselves there, as the pond-weed shoots did; they merely lie by, like the whirligig beetles, as you can see one of them preparing to do in the left-hand corner of No. 10. All the living material is drained from the leaves into these winter bulbs. The pond freezes over, and the remnant of the floating leaves decay; but the bulbs lurk quietly in the warm mud of the bottom, protected by a covering of close-fitting scale-leaves.
In No. 11 we learn the end of this quaint little domestic drama. Spring has come, and the pond has thawed again. The winter buds of the frogbit now undergo certain spongy internal changes, due to warmth and growth, which make them lighter — lessen their specific gravity. Air-cells are developed in them. So they begin to rise again like bubbles to the surface. You can see in the illustration one bud still entangled in the slime on the bottom; another just starting to emerge; a third rising; and a fourth and fifth on the surface of the pool. Two more have already risen; one of these is just putting forth its first few kidney-shaped leaves; another has now grown pretty strong, and is sending out a runner; from which a third little plant is even beginning to develop. In time, hundreds of such runners are sent forth in every direction, till the surface of the pond, in suitable places, is covered with a network of tangled and interlacing frogbits. They always seem to me in this way the plant-counterparts of the whirligig beetles; and it is because of this queer analogy in their mode of life that I have figured the two here in such close connection.
Indeed, I hope I have now begun to make it clear to you that the difference of habit between plants and animals is not nearly so vast as most people imagine. It is usual to think of plants as merely passively existing. I have tried, here and elsewhere, to lay stress rather upon the moments in life when plants are doing something, and thus to suggest to my readers the close resemblance which really exists between their activities and those of animals. The more you watch plants, the more will you find how much this is true. And in a case like that of a pond frozen in winter, where both groups have to meet and face the self-same difficulty, it is odd to note how exactly similar are the various devices by which either group has succeeded in surmounting it.
When you skate carelessly over the frozen pond in winter, you never perhaps reflect upon all the wealth of varied life
that lies asleep beneath your feet. But it is there in abundance. The smaller newt, to be sure, has gone ashore to hibernate: but his great crested brother lurks somnolent in the mud, like a torpid bear or a sleeping dormouse. Frogs huddle buried in close packed groups at the centre, massed together in the soft ooze for warmth and company. Many kinds of aquatic snails slumber peaceably hard by, with various beetles beside the whirligigs. As for eggs and spawn and larvæ or pupæ, as well as petty crustaceans, you could count them by the dozen. Seeds are there, too, and buried plants of water-crowfoot, and winter shoots and winter buds, and a whole world of skulkers. The pond seems dead, if you look only at its hard and frozen top; but in its depths it encloses for kind after kind the manifold hope of a glorious resurrection. Let May but come back with a few genial suns, and forthwith, the water-crowfoot spreads its white sheet of tender bloom; the whirligig dances anew; the newts acquire their red and orange spots and their decorative crests; strange long-legged creatures stalk on stilts over the glass of the calm bays, and tadpoles swarm black and fat in the basking shallows. The pond, it seems, was not dead but sleeping. Spring sounds its clarion note, and all nature is alive again.
X. BRITISH BLOODSUCKERS
I WRITE this title with peculiar pleasure, because it is so nice to be able for once to apply it literally. With its figurative use I am already too familiar. In some tropical countries the free-born Britons who are sent out in the Government employment to protect the natives or the coolies or the negroes, as the case may be, from their aggressive brethren, are commonly known to their planter neighbours as “British bloodsuckers” — apparently because, like most other members of Civil Services elsewhere (except the Turkish), they get paid for their services. This use of the phrase is so well known to me, even as applied to myself, that I rejoice in being able to employ it here, without political prejudice of any sort, with reference to the habits of the mosquito and the horse-fly. Nobody, I suppose, is interested to deny that mosquitoes and horse-flies do suck blood; nobody feels the faintest sympathy for the misdeeds of those sanguinary and unpleasant creatures. Now, it is always delightful to find a lawful outlet for our evil passions: all the world turns out to hunt a mad dog. I love to flick the heads off tall thistles with my stick as I pass, and salve my scruples with the thought that they are the deadly enemies of the agricultural interest. If there were no thistles, there would be nothing in the shape of a large and conspicuous flower whose head one could knock off with a clear conscience.
