by Grant Allen
You must not suppose, however, that in doing all this the soldanella is displaying any extraordinary amount of unusual originality. Its speciality consists merely in the somewhat abnormal volume of heat which it generates. A great many plants, indeed, proceed much as the soldanella does in the matter of laying by materials for future growth in the leaves, and using these up in the act of flowering. Take, for example, the famous and often somewhat exaggerated case of the so-called “aloe,” or American agave. It is commonly said that “the flowering of an aloe” takes place but once in a hundred years. This is a poetical fiction. As a matter of fact, the agave flowers on an average after fifteen or twenty years, and then dies down utterly. Every visitor to Italy or the Riviera knows this huge plant well — a gigantic house-leek in form, with its big spiny leaves and its points sharp as a needle, which defend it as by a bristling row of bayonets. Now, the agave lays by its material for future growth in the thickened base or lower portion of its leaves; it thus forms a huge rosette, very much swollen and enlarged at the bottom. For years it goes on with exemplary patience, collecting supplies for its one act of flowering; then at last, feeling its time has come, it suddenly sends up a huge stalk, or trunk, like a vast candelabrum, fifteen, twenty, or even thirty feet high, and supporting at its top a great bunch of big yellow blossoms. This enormous stem, with its colossal cluster of branching blossoms, takes only a few weeks to grow; and as it rises and flowers, or still more as the immense capsules ripen their seeds, the bases of the leaves, once swollen and thick, become by degrees flaccid and empty. The stem and blossoms have drained them dry. At last, as the seeds fall, the whole plant dies away, having used itself up for ever in its one great act of flowering, just as the egg-laying rose-aphis uses itself up in its orgy of motherhood.
Now, this is much the same as the way in which soldanella behaves, except that soldanella continues to flower, spring after spring, for many years together. It does not exhaust itself in a single blossoming. Otherwise, the two plants, though so different in size, behave in much the same general fashion. For agave must necessarily evolve a great deal of heat during its rapid flowering period; but this heat is useless to it, as heat, just as the heat we evolve in running a race is, as such, of no advantage to us. The main difference here is that soldanella has need of the heat and employs it deliberately for its own purposes. In the struggle for existence, every point of advantage any creature possesses must tell in its favour, and the soldanella has thus been enabled to hold its own bravely in the intermediate belt at the margin of the ice-field. But its limits are narrow. In the open ground it is soon lived down by more hardy kinds, which rise higher into the air; its range is almost entirely bounded by a narrow belt just where the ice is melting. Above that point it cannot grow; below it taller enemies soon oust and dispossess it. It utilises its short time between these two impossibilities.
Strange as it sounds, too, the ice itself acts as a sort of protective blanket or coverlet to the trustful soldanella. Only a plant that could pierce the ice could ever have hit upon such a paradoxical mode of warming itself by its own internal combustion. If a herb that flowers in the open were to make experiments in warming itself in the same manner, its attempt would necessarily fail, because as fast as it heated the air the wind would blow the heated portion away, and the plant would therefore derive no benefit from its expenditure of fuel. But we all know how Esquimaux can live in a snow hut, keeping it warm inside by their own breath and the heat of their bodies. It is just the same in principle with the soldanella’s ice-cave. The little dome or cavern gets warmed within by the respiration of the flower-bud; and the heat thus produced is retained within the walls of the cavity. It is almost as though a mouse or other small animal were to try to bore a path for itself through an ice-barrier, not by gnawing the ice, but by breathing upon it slowly till it melted.
See, then, how absolutely the soldanella behaves like a man who is making a conservatory. It lays by fuel for the stove in its leaves to keep its flower-buds warm and to force them in spring, at a time when they could not blossom without the artificial heat thus supplied them. It keeps in this heat within a transparent covering, the doors of which are never opened. As for light, that reaches it through the crystal summit. But it employs the heat also to bore its way out; and, as its ultimate object is to get its young seeds fertilised, it finally pushes its flowers out into the open air, where they may receive the attentions of the fertilising insects — just as the gardener does, without knowing why, when he wishes seed set. The pendent bell-shaped blossoms, again, even after they open, are admirably adapted for keeping in the heat; and they are also exactly fitted to the shape and size of the bees and flies that act as their chartered carriers of pollen. A plant, in short, has to accommodate itself at every point to the needs of its situation; it has to secure for itself a firm foothold in the soil, and a due share of food from the surrounding air (for its diet after all is chiefly gaseous); it has to take care that its pollen shall be duly dispersed, and its seedlets fertilised; and finally, it has to see that its young are satisfactorily settled in the world, and deposited on likely spots where they can germinate to advantage. It must be a good parent as well as a prudent and cautious adventurer.
The struggle for life carried on under these circumstances has sharpened the wits of plants to a far higher degree than most people imagine. Plants have developed almost as many dodges and devices for securing food or avoiding enemies as animals themselves have; and this single instance enables us to see with what forethought and cleverness they often provide against adverse chances. Soldanella, indeed, could not exist at all upon its ice-clad heights if it did not lay up food and fuel in summer against the needs of winter, like the bee and the ant; if it did not burn up its own fat for warmth, like the dormouse; if it did not tunnel the ice as the mole tunnels the earth; if it did not retire beneath the snow-sheet on the approach of winter as the queen wasp retires into the shelter of the moss when frosts begin to kill her worker sisters, or as the squirrel retires into his hole in a tree at the approach of December. Ancestral instinct teaches the one just as much as it teaches the other; and those who have closest watched the habits and manners of plants have the highest respect for their industry and intelligence.
Looked at from this point of view, we may consider indeed that every seed, bulb, or tuber is not merely a reservoir of material for future growth, but also a reservoir of fuel for supplying the heat necessary to the first stages of sprouting or germination. And without elaborating this question further, I may add that if you will examine closely many early spring buds and flowers, especially such as willow and hazel catkins, you will find not only that they are formed over winter and enclosed in warm overcoats to protect them from the cold, but also that they grow in spring before the air is warm enough to stimulate growth directly — or in other words, that they depend in part for heat on the consumption of their own internal fuels.
III. A BEAST OF PREY
THE lion, we all know, is the king of beasts; a Tippoo Sahib of the desert, he treats his subjects with the simple and unaffected cruelty of an Oriental monarch. The tiger is also a somewhat ruthless animal; he prefers to eat his dinner living. But for sheer ferocity and lust of blood, perhaps no creature on earth can equal that uncanny brute, the common garden spider. He is small, but he is savage. Lions and tigers are credited at least with the domestic virtues; if we object to the king of beasts that (as Thersites said of Agamemnon) he devours his people, we may be told in extenuation that, like Charles I., he is a good husband and a model father. No such plea can be urged in mitigation of the misdeeds of that bloodthirsty wretch, the female spider. Not only does this Messalina among small deer poison, and then eat, her prey, but she also often kills and makes a meal upon her own lawful spouse, the father of her children. In selecting a garden spider of my acquaintance, therefore, as a theme for a short biography, I do not desire to hold her up to the young, the gay, the giddy, and the thoughtless as a pattern for imitation
. She does not point a moral with the ant. On the contrary, she must rank with Semiramis and the famous queen who dwelt in the Tour de Nesle as a shining example of abandoned and shameless wickedness.
Spiders are not all alike. They are of many kinds, and of various families. So I shall begin by remarking that Rosalind, the particular lady whose portrait I have here presented to you in words, and whose life-history my colleague, Mr. Enock, has drawn for you from nature, belongs to the most familiar race of her kind, the true garden spider, which constructs the best-known and most perfect examples of regular geometrical webs. We called her Rosalind because she was a maiden of hunting proclivities, who lived under the greenwood in our own particular Forest of Arden. But her ways were not lovable. She killed flies in a fashion that would have brought up fresh tears in the eyes of Jacques; and she devoured her Orlando with all the callous ferocity of a South Sea Islander.
I will begin at the beginning with my eight-legged friend’s biography. Rosalind was hatched in spring from a cosy cocoon or ball of eggs deposited by her affectionate, but otherwise cruel, mamma in the preceding October. She was one of a large family — say, seven or eight hundred. The cocoon was composed of yellowish silk, and attached, as the first illustration shows you (No. 1), to the under side of a piece of trellis-work, against a cottage wall, partly overgrown with ivy. Within this snug abode the tiny eggs, each wrapped in its own internal coverlet, escaped the cold of winter, and hatched out in early spring with the first burst of warm sunshine. It was a bright May morning when they ventured abroad. The tiny spiders, just freed from their shell, with its outer great-coat, let themselves down by short webs to an ivy-leaf below, where they clustered for a while, after the queer fashion of their species, in a sort of close-knit crèche or communal nursery. Gathering together in a compact ball or mass, like bees when they swarm, the wee creatures began by spinning in common a covering of thin silk, in whose midst they lay rolled up in an apparently inextricable tangle of legs and bodies. That is the universal fashion of young spiders of this kind. But if you touch them with a straw, a strange commotion takes place all at once in the crowded home. The mass unrolls itself. The six or eight hundred small beasts within wake all together to a sense of their responsibilities; the ball, which looks at first like a cherry-stone, divides as if by magic into so many eager and frightened animals; and the spiderlings disperse like the nations at Babel. Each goes his or her own way helter-skelter, in search of a suitable place to commence operations as a general fly-catcher; and in two minutes the space around is fairly colonised by spiders, who set their snares at once with exemplary industry. I am glad to be able to give them credit for the one good quality they do really possess; though I am aware that in their case industry is often only another name for consummate greediness.
From the general gathering of the clan in which our Rosalind thus took part she was rudely roused by the touch of such a straw; and, emerging in haste into the open world, the great, cruel world, amidst whose temptations henceforth she was to earn her dishonest livelihood, she cast about her for a favouring breeze to waft her first-spun threads to some lucky position. It was a delicate operation. Balancing herself with her eight legs on the edge of an ivy-leaf beside her native corner (as you see her graphically represented in No. 2), she span, to begin with, a few short ends of silk, which she exposed to a passing current of air by tilting her back up in her most persuasive manner. Where the silk came from, and how she managed to spin it, we will inquire hereafter; for the moment, it must suffice to say that the wind was polite enough to fall in with her wishes, and to waft one of her threads to a secure position. There it gummed itself automatically by its own stickiness. Mr. Enock, who timed her, reports the interval she took in fixing this first thread as thirty-six seconds. The cable itself was drawn out from Rosalind’s spinnerets by the force of the wind, as she stood with her head down and her body protruding; in little more than half a minute she was climbing up a line fifteen inches long, which had caught and glued itself on the edge of a jasmine leaf. For the silk is sticky and viscid, like the glue of a mistletoe, when first produced; it only hardens as it dries, so that it can be readily moored in its first state to whatever it touches. You may compare it in this respect to hot sealing-wax, or to the early pulled stage in toffee-making.
In No. 3, again, we see Rosalind’s first snare, constructed neatly, with the usual architectural and geometrical skill of her race, between the twigs of the jasmine bush. In the centre she sits, as is her wont, head downward. The method of making this snare is so interesting and curious, however, that I shall describe it at some length, with needful explanations.
Rosalind began by letting the wind fix an original base thread, pretty much by accident. As soon as she was satisfied with the lie of this, she formed a few others about it irregularly in a rough pentagon, as you see in the outer part of the web, merely to serve as a scaffolding for her future operations. But as soon as she had formed a careless angular figure all round the sphere of her projected snare, she let down a perpendicular thread from the top of her base, through the centre of her predestined home, and fastened it off at the bottom by gliding down it as she span it. Then, walking up this first ray-line again, she set to work once more a little to the right, spinning again as she walked, and fastened a second ray from the centre of the first to one of her outer cables. Next, time after time, she walked back to the centre, ran along the last ray made, trailing a thread as she went, and fastened each new line taut to one of the outer scaffoldings. So at last she had formed a regular set of rays like the spokes of a wheel, but as yet without any spiral connecting threads or mesh-like cross-pieces. The rays of this first framework were stout and thick, composed of several distinct strands, but very little viscid; they were built up of many threads each, in a manner to be hereafter described; and they hardened quickly on exposure to the air, for they were intended mainly to serve as beams, not as nets or insect-catchers.
Her ground-plan being thus complete, Rosalind next proceeded with great deliberation to add the meshes of the web (which are the practical insect-catchers) by connecting the rays with the spiral network. In doing this, she followed a regular method. Beginning at the centre, she fastened a thinner cord to one of the spokes, and worked slowly outward, fixing the line to each ray as she went by the aid of her hind-legs, which are almost hand-like. Then, reversing the process, she fastened another thread to one of the outer cables, and carried it back through the spokes in a similar spiral to the hub or centre. These two spiral threads are the ones which she specially designed for catching her prey; they are thinner than the spokes, but are closely studded through all their length with tiny drops of sticky stuff like bird-lime, admirably adapted for snaring insects. You can see the drops, if you look close, even with the naked eye; and they are very clearly visible by the aid of a pocket lens.
How is the web itself manufactured and produced? What is its raw material? Well, to answer that question I must give you here some brief description of the personal appearance of Rosalind and her sisters. The garden spider, you know (and as you can see her in No. 6), is a great, soft, eight-legged creature, about half an inch long, though her comparatively insignificant husband is very much smaller and less conspicuous. She consists, in the main, of two parts, the foremost of which, though it rejoices in the scientific title of the cephalothorax (science is always so careful to give things nice easy names while it is about it!), may be more popularly described for most practical purposes as the head; and to this large compound head are attached the eight long-jointed, hairy legs, with the muscles that move them. The other half of the spider consists of the abdomen or stomach, a soft, round bag, quaintly marked like a quail’s head, and very squashy in appearance. With this last part of herself, the garden spider spins her snare or web out of the manufactured material of her own body. She spins it of her own digested contents. And as she has frequently to mend the web after various mishaps, which occur in the natural course of business — as when it
is broken by the wind, brushed against by passers-by, or torn and mangled by a big fly or wasp — you can readily understand that she must eat in proportion; which is, no doubt, the true cause of her almost incredible voracity. In point of fact, a healthy female spider spends all her time in catching prey and eating it.
In No. 4 we have a greatly enlarged back view of the spinnerets from which the threads are produced, and a still more enlarged side-view below of the separate little ducts from which the component strands issue. According to circumstances, she makes her threads simple or compound. The sticky fluid of which they are formed is secreted by powerful glands in the abdomen; it is then squeezed out through numerous minute tubes, of different calibres, and hardens in most cases when exposed to the air, though the spiral threads with the insect-catching drops on them maintain their viscid nature much longer, so as to gum the flies down, rather than entangle them in meshes, as with the common house-spider.
No. 5 shows us further details of some other interesting features in Rosalind’s anatomy. The upper figure represents three distinct varieties of the viscid threads, each with its own peculiar type of beads, adapted for catching larger or smaller insects. Every kind has its own beads spread for it. The flies get entangled in these, according to their size; and then, tearing the web to free themselves, find the coils only double round their legs and bodies.
But the spider does not content herself with merely catching insects; she poisons them as well. We had not watched Rosalind long in her chosen lair before we discovered that she did not live in her geometrical web; that was merely her hunting-net; her private residence consisted of a snug little cell or nest, under shelter of a rose-leaf, at a few inches’ distance from the centre of the snare; and in this quiet home it was her habit to rest unseen, under cover of the shady leaf, until prey came within measurable distance of her sphere of practical politics. But she kept up communications with the seat of war. From the centre of the snare to the nest she had stretched a stout, thick line, along which she could run easily on the slightest indication of a prospective victim looming up in the background. Moreover, this cable or thread seemed to be connected by its different strands with various parts of the snare; at any rate, it acted as a telegraphic communicator between the home, strictly so called, and the place of business. For Rosalind used always to recline at her ease with one hand-like claw placed steadily on the line of communication; thus seated, she would watch with cat-like stealth for any chance of a victim. The moment a fly touched the snare, however lightly, it would set up a slight tremor of movement in the indicating thread; and, quick as lightning, informed by touch of its whereabouts, out Rosalind would dart, ready to go straight to the spot and suck that luckless creature’s life-blood.
