THE NATURALIST.

Otago Witness, Issue 2924, 30 March 1910, Page 77

THE NATURALIST.

Tlie Earthworm. "Worms," wrote Gilbert White in 1777, "seem to be great promoters of vegetation; which would proceed but slowly without them, by boring, perforating, and loosenin.; the soil, and rendering it pervious to rains and the fibres of plants, by drawing ' straws and stalks of all kinds into it, and, most of all, by throwing up such infinite numbers of lumps of earth. . . . The earth without worms would soon become cold, hard-bound, and void of fermentation; and/' consequently . sterile." These observations have since been confirmed and augmented largely by later naturalists, of whom none perhaps has thrown more light upon the habits of these underground toilers than Darwin, whose treatjse ■ on "Vegetable Moulds and Earthworms" is full of interesting facts gathered extensively from experimental observations. The earthworm, though possessing a welldeveloped circulatory system, has no special respiratory organs, breathing, apparently, through its skin. It possesses no organs of sight, but is affected by light through its anterior extremity, where its cerebral ganglia are situated, according to the degree of its intensity and duration, and probably is thus able-t<' distinguish between day and n'ght, and to escape danger from the many diurnal animals which prey upon it. It is very to vibrations, and , also to contact, using its extended anterior extremity, apparently, as an organ of touch. Its sense of smell seems to be confined to the perception of -certain odours; and the fact that it shows, a partiality towards certain varieties of cabbage leaves and also towards those of the carrot and wild cherry indicates a sense of taste. As regards food, the earthworm is omnivorous. It swallows an enormous quantity of earth, from which it extracts any digestible matter it may contain. It consumes all kinds of half-decayed leaves and flowers, which are dragged" into the mouths , of 'burrows to a depth of from one' to three , inches, and are prepared by moistening with a- fluid secretion, which ' quickly 'decomposes fresh leaves. " : ■'.-•'*..■■■'■' Worms often lie close beneath the mouths of their burrows, especially in the morning, presumably for warmth; a habit accounting for their wholesale destruction by the thrushes and blackbirds, which, during certain seasons, may be seen busy

throughout the country «n our lawns. When the ground is dry, owing to winter cold or summer heat, earthworms burrow to a considerable depth, and cease to work. The depth to which the worm burrows varies in accordance with dryness or cold, and the thickness of the upper soil. It has been known to reach a "depth of over six feet. Ordinarily, however, they inhabit only the superficial mould, which is usually from four or five to ten or twelves inches thick. The amount of earth brought to the surface of poor pasturage by worms has been calculated at ai much as 18 tons an acre per annum; a better idea of which may be gathered from the fact that 16.1 tons, estimated by Darwin as thrown up on an acre of Leith Hill Common during • a year, means a layer .1429 inches in thickness. Calculating 26,886 worms to exist in an acre of pasture land, which is only j half as many as the like space of garden J mould contain, to obtain 15 tons to the '■. acre in a year, would work out, evenly j divided among them, at 20oz for every ! worm. From whatever depths worms penetrate to they bring up earth, and the soil is actually, though but slightly, increased through their agency. But the most important work the earthworm performs is sifting the finer- from the coarser particles, and mingling the whole mould with vegetable debris.

) Arctic Pops.

| The dogs used in most British and Euro- ' pean Polar expeditions are of the breed known as Samoyedes, native of north-east Russia and Western Siberia, and not, as is generally suppesed, Esquimaux dogs. Mr Cecil Meares, as was intimated recently, has left for Siberia to procure dogs for Captain Robert Scott's South Polar enterprise, and the pack will be made up entirely of Samoyedes. Like all the dogs of the extreme northern latitudes, the Samoyede possesses the pointed nose, prick ears, curl tail, harsh outer coat, and woolly undercoat that are the* characteristics of the dogs of those regions, and it is one of the oldest of the old world breeds. Of almost unique intelligence, the Samoyede becomes particularly devoted to its master, and rejoices in the work of sledge-drawing, though it is made use of for hunting and kindred pursuits as well. Mr C. E. Borchgjei vink, who explored the Antarctic in 1899, ! left some Samoyede dogs on Stewart Island, I New Zealand, and descendants of those were used by Sir Ernest Shackleton in his late South Pole expedition. The few Esquimaux dogs "that have been used on expeditions have been invariably failures, and the difference between Samoyede and ' Esquimaux dogs is perhaps best explained • by a quotation from a letter of Mr Trevor- \ Battye; the only traveller who has actually 'lived among the Samoyede and Esquimaux peoples for any length of time. Mr Trevor-Battye says:—"The fact the Samoyede's dog is his friend, but the Esquimaux's only •> his servant, sufficiently explains the difference in character." The Esquimaux, is the true "husky" dog which, if let out of human control even for a moment, becomes an animated piece of savage ferocity, though by nature it is cowardly and treacherous. The Samoyede dog is easilv acclimatised in Britain, and breeds freely, but a comparatively insignificant number of Esquimaux dogs have thriven in this country, and' few, if any, puppies have been reared to maturity. The Samoyede dogs that I have had in my possession have been reliable and.affectionate comrades and devoted and protective companions, but I have always found the Esquimaux very l untrustworthy, with all the vices of the wild' wolf, which it so much resembles, and none of the virtues of the pet w olf- 'When at all hungry the Esquimau* dog does not hestitate to make a meal of any human baby it can lay hold of, and no Esquimaux mother would leave her children alone with the. dogs. The Samoyede, on the other hand, is an excellent nurse, and one of the dogs from the Jackson-Harmsworth expedition has been the nursery playmate of a friend's children for many years.

The Woscnuero.

I It is perhaps difficult to account for the | fact that certain very harmless fellow-crea-j tures of ours are almost invariably looked upon with repulsion, if not with absolute horror. The number of individuals who care to have snakes as pets is comparatively few," and those who are interested' in soiders must form even a smaller class. Sentiment is occasionally powerful enough, indeed, to overcome antipathy to what is loathsome. There are parts of Britain in which even a member of the so-called weaker sex will view with equanimity a red spider running over her sleeves, whereas she would tread remorselessly under foot the common or garden variety. For the red spider is a preeusor of the possession of wealth. The utility of the spider, the fact that it has a part to play in the economy of Nature, is very slowly being recognised in this country, but there lire regions of the world where sentiment has , given place to the conviction that certain classes, at any rate, of the insect play a role that is both useful and beneficial to j man. M. L. Diguet, . who has been on I a mission in a district of Mexico, which | he calls Miehoacan, has brought back tidings of a spider's nest Which is used by j the natives for self-nrotection during the. I rainv season, and which forms a notable ; addition to the adornment of the rooms in | which they live. In the Bulletin de la Societo Nationale d'Acclimatation . he describes the Mosquero, as it is called, which has been used as a remedy for the flyplague from time immemorial. At the beginning of the rainy season the exodus from the villages begins. The inhabitants stream up the wooded hillsides; and the picture he draws of the long procession of branches, each of which contains one or ■ more coveted Mosquero, reminds one of the wood of Dunsinane. The nests are large enough to cover a space of a couple of square yards, and are like a huge sponge. This is strung to the branches by thick threads which act as cables. Then .come the thinner and sticky ropes which are to act as catchers of the harmful,! unnecessary fly. The inside'of the nest' is , simply a mesh of interwoven lines, pierced with passages and galleries-^—all kept' in a state of perfect sweetness by a tiny parasite, one of the coleootera, swarms of which live and move, have their being, and find their nurture within its recesses. The season goes on; the nest increases concentrically in size. As each cloture is made it is secured by freshly made webs, and the remains, after host and parasite

have satisfied their appetites, become an integral part of the surface of the nest.