NATURALIST.

Dunstan Times, Issue 2336, 18 June 1906, Page 3

NATURALIST.

THE MYSTERY OP COMMON THlitflS Sir John Lubbock, in his address to the Internationa' * Congress of Zoologists at Cambridge, recently demonstrated in ways that the most simple can understand how much more there is still to know. Take, for instance, the common eel. Until quite recently its life history was absolutely unknown, Aristotle pointed out that eels were neither male nor female, and that eggs were unknown. This remained true until a few years ago. No ono bad ever seen the egg of an eel or a young eel lees than five centimetres (2tnj in length. Wo now know, thanks mainly to the researches of Qrassl, that the parent eels go down to the eea and breed in the depths of the ooean, in water not less than 3,000 feet below the surface. There they adopt a marriage dress of silver and their eyes considerably enlarge, so as to make the most of the dim light in the ocean depths. Take ono other instance—the fly of the King Charles oakapple so familiar to every schoolboy. In this case the females are very common, and the eggs were known, but no one had ever seen a male. Hartig in 1843 knew 28 Speotos of oynips, but in 28 years collecting had never seen a male in any of them. Now it la known that the gall flies from the King Charles oakapplo (which are all females) creep down and produce galls on the root of the oak, from which quite a dissimilar insect is produced, of which both sexes occur, and the female of which again produces the oakapple. Many animals possess organs apparently of sense aud richly supplied witn nerves which yet appear to have no relation to any sense known to us. They perceive sounds which are inaudible to ns, they see sights which are not visible to us, they, perhaps, possess sensations of which we have no conception. The familiar world which surrounds us must be J a totally different place to other animals. To them it may be full of musio which we cannot hear, of colour which we canuot see, of sensations which wo lannot realise.

More students (Sir John observed) would doubtless devote themselves to science if it were not so systematically repressed in our schools ; if hoys and girls were not given the impression that the field of discovery is wellnigh exhausted. But that is far from being tho ca e. ‘Wo are, in fact, ouly on the threshold of tho temple of science.’

LITTLE SPINNERS AND WEAVERS

The spiders of tropical countries are fi3rco, poisonous creatures, only a little less to bo dreaded than venomous serpents; but, in spite of prejudice aud old wives’ tales, mo-t of our northern species arc comparatively harmless, and only ask to bo unmolested while they make war upon the insect worll. Dame Aracbne appears to taka very good care of tho round, silky cocoon containing her eggs, and, in case of danger, may frequently be seen carrying it upon Lor back to tome place of safety. When tho eggs are hatched, tho young ladies remain iu tho cocoon until of considerable size, and when finally released by tho mother, keep close to her side, cr cling to her body until such time as she appears to think them old enough to wtau, when she deliberately shakos them off, and leaves them to their fate.

n spito of maternal affection, when provisions are scarce, the weaklings are frequently killed to serve for the dinner or supper of the rest of tho fami'y, often numbering a hundred. Tho lather is much smaller than the mother, and, it is said, that Madame Arachne has an unfortunate propensity to snap off a leg now and then, should ho chance to offend her, or, upon occasion, she may even dine upon him. In feeding her brood the mother holds the doomed insect in her claws, and tho young spiders, as many as can, gather round it and suck the juices from ffs body ; when they havo eaten enough, others take their places. llie young spiders attain their full growth in alout two months, and during that period charge their jiokofs, or moult, six times. When ono of them fiods his skin getting too tight for him, he spins a thread from some twig or leaf, and then, hanging from it, Lead downwards, he proceeds to shake or kick off his jacket, which very conveniently splits open at both front and back. The now skin, which he finds underneath, is thin and quite soft at first, but soon hardens. The body of a spider cousiats of a head and tnorax with a soft, generally globose abdimeu. The head and thorax aro in one piece, and are covered with a tough horny skia. Attached to tho thorax are four pairs of jointed logs, each one of which has sharp claws or falcea, incorrectly termed mandibles. Three falocs consist of two parts, a base, covered with short hairs, and a curved book fer seizing and killing the prey. From openings at the tip of each hook, tiny pipes or canals lead tho poieoa (for benumbing and killing prey) stored at tho base of the lower joints.

Near tho top ot tho head are the eyes, eometimestwo, four or six, but usually eight, airasiged iu two rows, four in each row. I hey arc not movable like ours, but are fixed in tho head, and in order to look above, below and on all sides, in search of food and to guard against danger, there is need of all. For breathing, each spider has from two to four lung-sacs, with tubes or openings called spiracles. Near tho end of tho abdomen, upon the under side, are two or more pairs of spinnerets, Dame Spider’s apparatus for spinning webs, snares, nests aud cocoons. These look not unlike tiny knobs, and, seen tfcrcugh a glass, show a great number of minute openings. From these tho fine silken filaments—hundreds of them—pass out, and, at a little distance, unite and make one thread, fine as gossamer, yet wonderfully strong. In making her web, the garden 'spider first spine tho Jong rays or spokes, gaming each thread with her feet and securely fastening it to some stem or twig. Then, beginning at the centre, she spins across from ray to ray, round and round, gluing each thread in place until the beautiful geomeiric web is completed.

Other spiders Lava various plans and pattorus. Wo have all soon tho lovely dawgemmed webs, that spangla the gras on summer morning's. If wo examine these closely we shall see than each one has a silken tunnel leading out into the grass, a sort of back door where the spider may escape from her enemies, or sit at her ease watching for some unwary fly. Some spiders like to make their nests in the ground. They dig n round tunnel from a few Inches to a foot or two in depth, and lino it with tho finest and softest silk. To keep out intruders, they spin a lilllo door that will just fit into tho opening; this they cover with fine earth or oiay, amt so on until, •andwioh-like, the tiny door may be very thick. It is then joined to the silken lining by a woven hiuge, upon which it swings easily, and, whoa an inquisitive, unwelcome caller come?, the occupant promptly shuts tho door in his face and holds it in place with her claws, saying plainly in spider vernacular, * Not at home to you, sir.’ The droadod tarantula of warm climates is one of the largest of these * trap door spiders.’