In the end, Eliza laid a large number of eggs in a silken cocoon, in shape a balloon, and secreted, like the web, by her invaluable spinnerets. Indeed, the real reason—I won't say excuse—for the rapacity and Gargantuan appetite of the spider lies, no doubt, in the immense amount of material she has to supply for her daily-renewed webs, her home, and her cocoon, all which have actually to be spun out of the assimilated food-stuffs in her own body; to say nothing of the additional necessity imposed upon her by nature for laying a trifle of six or seven hundred eggs in a single summer. And, to tell the truth, Lucy and Eliza seemed to us to be always eating. No matter at what hour one looked in upon them, they were pretty constantly engaged in devouring some inoffensive fly, or weaving hateful labyrinths of hasty cord round some fiercely-struggling wasp or some unhappy beetle.
We weren't fortunate enough, I regret to say, to see Eliza's eggs hatch out from the cocoon; but in other instances, especially in Southern Europe, I have noticed the little heap of well-covered ova, glued together into a mass, and attached to a branch or twig by stout silken cables. If you open the cocoon when the young spiders are just hatched, they begin to run about in the most lively fashion, and look like a living and moving congeries of little balls or seedlets. The common garden spider lays some seven hundred or more such eggs at a sitting, and out of those seven hundred only two on an average reach maturity and once more propagate their kind. For if only four lived and throve, then clearly, in the next generation, there would be twice as many spiders as in this; and in the generation after that again, four times as many; and then eight times; and so on ad infinitum, until the whole world was just one living and seething mass of common garden spiders.
What keeps them down, then, in the end to their average number? What prevents the development of the whole seven hundred? The simple answer is, continuous starvation. As usual, nature works with cruel lavishness. There are just as many spiders at any given minute as there are insects enough in the world or in their area to feed upon. Every spider lays hundreds of eggs, so as to make up for the average infant mortality by starvation, or by the attacks of ichneumon flies, or by being eaten themselves in the young stage, or by other casualties. And so with all other species. Each produces as many young on the average as will allow for the ordinary infant mortality of their kind, and leave enough over just to replace the parents in the next generation. And that's one of the reasons why it's no use punishing Lucy and Eliza for their misdeeds in this world. Kill them off if you will, and before next week a dozen more like them will dispute with one another the vacant place you have thus created in the balanced economy of that microcosm the garden.
Our observations upon Lucy and Eliza, however, had the effect of making us take an increased interest thenceforth in spiders in general, which till that time we had treated with scant courtesy, and set us about learning something as to the extraordinary variety of life and habit to be found within the range of this single group of arthropods, at first sight so extremely alike in their shapes, their appearance, their morals, and their manners. It's perfectly astonishing, though, when one comes to look into it in detail, how exceedingly diverse spiders are in their mode of life, their structure, and the variety of uses to which they put their one extremely distinctive structural organ, the spinnerets. I will only say here that some spiders use these peculiar glands to form light webs by whose aid, though wingless, they float balloon-wise through the air; that others employ them to line the sides of their underground tunnels, and to make the basis of their marvellously ingenious earthen trap-doors; that yet others have learnt how to adapt these same organs to a subaquatic existence, and to fill cocoons with air, like miniature diving bells; while others, again, have taught themselves to construct webs thick enough to catch and hold even creatures so superior to themselves in the scale of being as humming-birds and sunbirds. This extraordinary variety in the utilization of a single organ teaches once more the same lesson which is impressed upon us elsewhere by so many other forms of organic evolution: whatever enables an animal or plant to gain an advantage over others in the struggle for life, no matter in what way, is sure to survive, and to be turned in time to every conceivable use of which its structure is capable, in the infinite whirligig of ever-varying nature.
MUD.
Even a prejudiced observer will readily admit that the most valuable mineral on earth is mud. Diamonds and rubies are just nowhere by comparison. I don't mean weight for weight, of course—mud is 'cheap as dirt,' to buy in small quantities—but aggregate for aggregate. Quite literally, and without hocus-pocus of any sort, the money valuation of the mud in the world must outnumber many thousand times the money valuation of all the other minerals put together. Only we reckon it usually not by the ton, but by the acre, though the acre is worth most where the mud lies deepest. Nay, more, the world's wealth is wholly based on mud. Corn, not gold, is the true standard of value. Without mud there would be no human life, no productions of any kind: for food stuffs of every description are raised on mud; and where no mud exists, or can be made to exist, there, we say, there is desert or sand-waste. Land, without mud, has no economic value. To put it briefly, the only parts of the world that count much for human habitation are the mud deposits of the great rivers, and notably of the Nile, the Euphrates, the Ganges, the Indus, the Irrawaddy, the Hoang Ho, the Yang-tse-Kiang; of the Po, the Rhone, the Danube, the Rhine, the Volga, the Dnieper; of the St. Lawrence, the Mississippi, the Missouri, the Orinoco, the Amazons, the La Plata. A corn-field is just a big mass of mud; and the deeper and purer and freer from stones or other impurities it is the better.
But England, you say, is not a great river-mud field; yet it supports the densest population in the world. True; but England is an exceptional product of modern civilization. She can't feed herself: she is fed from Odessa, Alexandria, Bombay, New York, Montreal, Buenos Ayres—in other words, from the mud fields of the Russian, the Egyptian, the Indian, the American, the Canadian, the Argentine rivers. Orontes, said Juvenal, has flowed into Tiber; Nile, we may say nowadays, with equal truth, has flowed into Thames.
There is nothing to make one realize the importance of mud, indeed, like a journey up Nile when the inundation is just over. You lounge on the deck of your dahabieh, and drink in geography almost without knowing it. The voyage forms a perfect introduction to the study of mudology, and suggests to the observant mind (meaning you and me) the real nature of mud as nothing else on earth that I know of can suggest it. For in Egypt you get your phenomenon isolated, as it were, from all disturbing elements. You have no rainfall to bother you, no local streams, no complex denudation: the Nile does all, and the Nile does everything. On either hand stretches away the bare desert, rising up in grey rocky hills. Down the midst runs the one long line of alluvial soil—in other words, Nile mud—which alone allows cultivation and life in that rainless district. The country bases itself absolutely on mud. The crops are raised on it; the houses and villages are built of it; the land is manured with it; the very air is full of it. The crude brick buildings that dissolve in dust are Nile mud solidified; the red pottery of Assiout is Nile mud baked hard; the village mosques and minarets are Nile mud whitewashed. I have even seen a ship's bulwarks neatly repaired with mud. It pervades the whole land, when wet, as mud undisguised; when dry, as dust-storm.
Egypt, says Herodotus, is a gift of the Nile. A truer or more pregnant word was never spoken. Of course it is just equally true, in a way, that Bengal is a gift of the Ganges, and that Louisiana and Arkansas are gifts of the Mississippi; but with this difference, that in the case of the Nile the dependence is far more obvious, far freer from disturbing or distracting details. For that reason, and also because the Nile is so much more familiar to most English-speaking folk than the American rivers, I choose Egypt first as my type of a regular mud-land. But in order to understand it fully you mustn't stop all your time in Cairo and the Delta; you mustn't view it only from the terrace of Shepheard's Hotel or the rocky platform of the Great Pyramid at Ghizeh: you must push up country early, under Mr. Cook's care, to Luxor and the First Cataract. It is up country that Egypt unrolls itself visibly before your eyes in the very process of making: it is there that the full importance of good, rich black mud first forces itself upon you by undeniable evidence.