Fig. 48.—View of the lower surface of the head and body of a large Burmese spider, known as Liphistius, to show the spinnerets (3 and 4), which are really reduced or rudimentary legs, and are in this spider retained in their original position, instead of being pushed down to the end of the body, as they are in all other spiders (see [Fig. 49], spn), I. to VI., the basal joints of the legs and palps of the head-region; 1, the first abdominal segment; 2, the second; 3 and 4, the legs of the third and fourth abdominal segments, which are the spinnerets; 11, the eleventh abdominal segment—in front of it rudiments of the segments 5 to 10 are seen; an, anus; a, b, inner and outer lobes of the first pair of spinnerets.
There are 500 different kinds of spider carefully described as occurring in the British Islands, and about 2000 others from remoter regions. Precisely which of them forms the “gossamer” of our meadows it is difficult to say, as all have the habit of secreting a viscid fluid from one or two pairs of projecting spinning knobs or stalks, which are seen at the hinder end of the body (Figs. [48], [49], and [50]). The viscid fluid is poured out by a great number of minute tubes, and hardens at once into a thread, which is wonderfully fine, yet strong. Different kinds of spiders make use of these threads for different purposes, hence their name “spinners.” Some make burrows in the ground and line them with a felt of these threads, others enclose their eggs in a case formed by winding them round the eggs, others form “snares” of the most marvellous mechanical ingenuity with them, by which insects are entangled and are then paralysed by the poisonous stab of the spider’s claws, and have their juices sucked out of them at the spider’s leisure. The snares of spiders are in some species merely irregular webs fastened and suspended by threads, in other cases they are gracefully-modelled funnels or cups, whilst a third kind, the disc-like webs made up of radiating and circularly-disposed threads fixed in a geometrical pattern, excel—in the mechanical precision of their workmanship and the masterly treatment of engineering difficulties—the constructions of any other kind of animal. It is amongst this kind of spiders that the formation by the spinning knobs of threads or lines and their use in various ways is most general and frequent. The smaller spiders expel the viscid thread, drawing it out from their bodies by their own movement away from the object to which it at first adhered. When it breaks loose from that support it is carried upwards by air-currents and drawn out from the spinners body to many yards’ length ([Fig. 47]). It then becomes a “flying-line,” and the spider may sail away on it or run up it and disappear. The celebrated story of the Indian juggler’s performance—traditional and even solemnly attested by witnesses, but failing to pass the test of photography—must have been suggested by this common, yet wonderful, proceeding of small spiders. The juggler, standing in an open place, surrounded by a ring of spectators, uncoils a rope, 50 feet long, from his waist, and holding one end, throws the other up into the air. The rope, without any support, remains stretched and upright. A small boy now enters the ring and climbs up the rope, draws it up after him, and disappears with it in the upper air! That is an illusion, but it is precisely what thousands of small spiders are continually doing. A big spider—the well-grown female of the common garden spider, for instance, cannot do this—her thread is not strong enough, and her weight is too great. But the male of the same species, who is much smaller, fortunately for him, can safely run on a hanging line—and thus can rapidly escape from the side of his mistress, who, after receiving his caresses, has an unpleasant habit of seizing, killing, and sucking the blood of the adventurous male, should he linger longer in her company, and fail in the agility and rapidity of his exit.
Fig. 49.—Section through the body of a spider to show the spinning organs. h, heart connected by four big veins with b, the lung-bosks or air-gills; f, genital lid; ov, ovary; a, the anus; spn, the three pairs of spinnerets or spinning warts; c, e, and d, the three kinds of glands producing liquid silk, viz., cylindrical, tree-form, and pyriform. These are one thousand in number in the common garden spider, and each has its separate spout or spigot standing up on one of the spinnerets (see next figure).
Fig. 50.—One of the two middle spinnerets of the common garden spider (Epeira diadema), to show the three kinds of spouts or spigots (one thousand in all) corresponding to the three kinds of silk-glands. Each kind of “spigot” pours out a different kind and size of thread. sp.c, one of the big spigots of the cylindrical glands; sp.t, middle-sized spigots belonging to the tree-form glands; ss and s.ss, the small-sized spigots of the very numerous pyriform glands.