Let us first enquire the direction and strength of the current. Dandelion-plumes, made lighter by the removal of their seeds, serve as my guides. Released above the chafing-dish, on the level of the table, they float slowly upwards and, for the most part, reach the ceiling. The emigrants’ lines should rise in the same way and even better.
The thing is done: with the aid of nothing that is visible to the three of us looking on, a Spider makes her ascent. She ambles with her eight legs through the air; she mounts, gently swaying. The others, in ever-increasing numbers, follow, sometimes by different roads, sometimes by the same road. Any one who did not possess the secret would stand amazed at this magic ascent without a ladder. In a few minutes, most of them are up, clinging to the ceiling.
Not all of them reach it. I see some who, on attaining a certain height, cease to go up and even lose ground, although moving their legs forward with all the nimbleness of which they are capable. The more they struggle upwards, the faster they come down. This drifting, which neutralizes the distance covered and even converts it into a retrogression, is easily explained.
The thread has not reached the platform; it floats, it is fixed only at the lower end. As long as it is of a fair length, it is able, although moving, to bear the minute animal’s weight. But, as the Spider climbs, the float becomes shorter in proportion; and the time comes when a balance is struck between the ascensional force of the thread and the weight carried. Then the beastie remains stationary, although continuing to climb.
Presently, the weight becomes too much for the shorter and shorter float; and the Spider slips down, in spite of her persistent, forward striving. She is at last brought back to the branch by the falling threads. Here, the ascent is soon renewed, either on a fresh thread, if the supply of silk be not yet exhausted, or on a strange thread, the work, of those who have gone before.
As a rule, the ceiling is reached. It is twelve feet high. The little Spider is able, therefore, as the first product of her spinning-mill, before taking any refreshment, to obtain a line fully twelve feet in length. And all this, the rope-maker and her rope, was contained in the egg, a particle of no size at all. To what a degree of fineness can the silky matter be wrought wherewith the young Spider is provided! Our manufacturers are able to turn out platinum-wire that can only be seen when it is made red-hot. With much simpler means, the Spiderling draws from her wire-mill threads so delicate that, even the brilliant light of the sun does not always enable us to discern them.
We must not let all the climbers be stranded on the ceiling, an inhospitable region where most of them will doubtless perish, being unable to produce a second thread before they have had a meal. I open the window. A current of lukewarm air, coming from the chafing-dish, escapes through the top. Dandelion-plumes, taking that direction, tell me so. The wafting threads cannot fail to be carried by this flow of air and to lengthen out in the open, where a light breeze is blowing.
I take a pair of sharp scissors and, without shaking the threads, cut a few that are just visible at the base, where they are thickened with an added strand. The result of this operation is marvellous. Hanging to the flying-rope, which is borne on the wind outside, the Spider passes through the window, suddenly flies off and disappears. An easy way of travelling, if the conveyance possessed a rudder that allowed the passenger to land where he pleases! But the little things are at the mercy of the winds: where will they alight? Hundreds, thousands of yards away, perhaps. Let us wish them a prosperous journey.
The problem of dissemination is now solved. What would happen if matters, instead of being brought about by my wiles, took place in the open fields? The answer is obvious. The young Spiders, born acrobats and rope-walkers, climb to the top of a branch so as to find sufficient space below them to unfurl their apparatus. Here, each draws from her rope-factory a thread which she abandons to the eddies of the air. Gently raised by the currents that ascend from the ground warmed by the sun, this thread wafts upwards, floats, undulates, makes for its point of contact. At last, it breaks and vanishes in the distance, carrying the spinstress hanging to it.
The Epeira with the three white crosses, the Spider who has supplied us with these first data concerning the process of dissemination, is endowed with a moderate maternal industry. As a receptacle for the eggs, she weaves a mere pill of silk. Her work is modest indeed beside the Banded Epeira’s balloons. I looked to these to supply me with fuller documents. I had laid up a store by rearing some mothers during the autumn. So that nothing of importance might escape me, I divided my stock of balloons, most of which were woven before my eyes, into two sections. One half remained in my study, under a wire-gauze cover, with, small bunches of brushwood as supports; the other half were experiencing the vicissitudes of open-air life on the rosemaries in the enclosure.