THE NATURALIST.

Otago Witness, Issue 2056, 20 July 1893, Page 48

THE NATURALIST.

Natural Selection at Fault.

J. W. Slater writes to Science as follows :— We are ' genera^y told by crfcbodox Darwinians that both the structure and the actions of animals are to a great extent dependent Upon natural selection. Any organ, cr any habit which is not advantageous to its speciep, will be, it is said, promptly Buppressed as a possible danger, or at least an unremunerative demand. Yet there-are a few cases of habits which seem to have been acquired or maintained in flat contradiction to this doctrine. Every one knows ttaa*; the Felidce, from the Bengal tiger down to oir domestic mouser, when they have ee'zed a prey do not at once kill and, devour it, but either torment it or at leasb sit and watch it for some time before administering the fatal bite or blow. The consequence is that the victim sometimes escapes, as we all have witnessed when pussy is plajin'g with a mouse. One instance is at least on record where a man, struok down by a tiger, quietly drew a dagger and Btabbed the assailant to the heart. This could not have been done with a beast of ' prey of the canine or ursine family, as they do not allow time for devising and executing Buch a manoeuvre. Hence we see that the peculiar conduct of the cats is disadvantageous to themselves, and we aßk why it haa not been abandoned. Certainly any cat which should at once devour any mouse or bird which it had caught wonld, in times of scarcity, have a decided advantage over its fellow cats. „..,. Similarly injudicious is the conduct of the domestic hen. As soon as she has lain an egg she at once announces the fact to all whom it may concern by her well-known oaokling.

What benefit is this outcry to herself or to her species ? On the contrary, the outcry is heard by animals which are given to stealing eggs, and is understood by monkeys, if we may accept the evidence of La Vaillant. There again, therefore, we have a line of conduct quite contraiy to what natural selection would determine.

la man there is no*", indeed, a habit, but an organ whioh has lost its uses, yet is still developed in • eveiy child brought into the world. The onter ear was formerly provided with muscles by which it could be turned toward any sound for its better recognition. Tue3e muscles have become obsolete by hereditary disuse, so>hat in all normal subjects the ear is motionless. That it could formerly be directed so as the better to receive a sound will the less be denied as it survive 1 * in certain exceptional individuals ; bnt as it is absent in the great bulk of our species, the question arises, Why does the external ear not gradually cease to be developed ? No one can now contend that it is useful.

A Leech's Jaws.— A leech has three jaws, which form a triangle. The Last op the Lammergeyebs. — It is believed that the lammergeyer, or alpine vulture*, has become completely extinct in Switzerland, a solitary female spacimen, which had dwelt on the Biotchhorn during the last 25 years, having at last fallen a victim to poison. The Spidbb. — It is probable that nine people out of ten would clasß the spider as an insect'; this, however, is not the case. With scorpions and mites spidere form a a class in the animal kingdom known as Arachnidse. The name is derived from a mythical personage called Arachne, the daughter of a purple dyer of Lydia, who was fabled to have challenged Minerva to a

trial of skill in spinning. So indignant was the goddess at this act of boldnees that she forthwith transformed the hapless challenger into a spider, presumably in order that she might have the best possible opportunity of practising the art on which she prided herself so mucb. Spiders differ from insects in five main particulars : Their eyes are simple instead of compound; they have eight legs in place of six ; they do not pass through the metamorphoses which are characteristic of insects; they have no antennas, and their breathing is accomplishd by means of organs which combine the functions of lungs and gills, instead of by tubes pervading their bodies. These points of distinction are sufficient to determine the fact that it is impossible to class spiders as insects. — Science Sittings.