Save in the case of the roof supplied by a large stone, we see that the site selected hardly satisfies proper hygienic needs. The Epeira seems to realize this fact. By way of an additional protection, even under a stone, she never fails to make a thatched roof for her eggs. She builds them a covering with bits of fine, dry grass, joined together with a little silk. The abode of the eggs becomes a straw wigwam.
Good luck procures me two Cross Spiders’ nests, on the edge of one of the paths in the enclosure, among some tufts of ground-cypress, or lavender-cotton. This is just what I wanted for my plans. The find is all the more valuable as the period of the exodus is near at hand.
I prepare two lengths of bamboo, standing about fifteen feet high and clustered with little twigs from top to bottom. I plant one of them straight up in the tuft, beside the first nest. I clear the surrounding ground, because the bushy vegetation might easily, thanks to threads carried by the wind, divert the emigrants from the road which I have laid out for them. The other bamboo I set up in the middle of the yard, all by itself, some few steps from any outstanding object. The second nest is removed as it is, shrub and all, and placed at the bottom of the tall, ragged distaff.
The events expected are not long in coming. In the first fortnight in May, a little earlier in one case, a little later in the other, the two families, each presented with a bamboo climbing-pole, leave their respective wallets. There is nothing remarkable about the mode of egress. The precincts to be crossed consist of a very slack net-work, through which the outcomers wriggle: weak little orange-yellow beasties, with a triangular black patch upon their sterns. One morning is long enough for the whole family to make its appearance.
By degrees, the emancipated youngsters climb the nearest twigs, clamber to the top, and spread a few threads. Soon, they gather in a compact, ball-shaped cluster, the size of a walnut. They remain motionless. With their heads plunged into the heap and their sterns projecting, they doze gently, mellowing under the kisses of the sun. Rich in the possession of a thread in their belly as their sole inheritance, they prepare to disperse over the wide world.
Let us create a disturbance among the globular group by stirring it with a straw. All wake up at once. The cluster softly dilates and spreads, as though set in motion by some centrifugal force; it becomes a transparent orb wherein thousands and thousands of tiny legs quiver and shake, while threads are extended along the way to be followed. The whole work resolves itself into a delicate veil which swallows up the scattered family. We then see an exquisite nebula against whose opalescent tapestry the tiny animals gleam like twinkling orange stars.
This straggling state, though it last for hours, is but temporary. If the air grow cooler, if rain threaten, the spherical group reforms at once. This is a protective measure. On the morning after a shower, I find the families on either bamboo in as good condition as on the day before. The silk veil and the pill formation have sheltered them well enough from the downpour. Even so do Sheep, when caught in a storm in the pastures, gather close, huddle together and make a common rampart of their backs.
The assembly into a ball-shaped mass is also the rule in calm, bright weather, after the morning’s exertions. In the afternoon, the climbers collect at a higher point, where they weave a wide, conical tent, with the end of a shoot for its top, and, gathered into a compact group, spend the night there. Next day, when the heat returns, the ascent is resumed in long files, following the shrouds which a few pioneers have rigged and which those who come after elaborate with their own work.
Collected nightly into a globular troop and sheltered under a fresh tent, for three or four days, each morning, before the sun grows too hot, my little emigrants thus raise themselves, stage by stage, on both bamboos, until they reach the sun-unit, at fifteen feet above the ground. The climb comes to an end for lack of foothold.
Under normal conditions, the ascent would be shorter. The young Spiders have at their disposal the bushes, the brushwood, providing supports on every side for the threads wafted hither and thither by the eddying air-currents. With these rope-bridges flung across space, the dispersal presents no difficulties. Each emigrant leaves at his own good time and travels as suits him best.