THE NATURALIST.

Otago Witness, Issue 1970, 22 August 1889, Page 37

THE NATURALIST.

The Theory of Natural Selection. The theory of natural selection rests on two main classes of faots which apply to all organised beings without exception-, and which thus take tank as fundamental principles or laws. The first is the power 'of rapid multiplication in a geometrical progression; the second, that the offspring always Vary slightly from the parentsj though generally very closely resembling them. From the first fact or law there fplllows, necessarily, a constant struggle for existence ; because, while the offspring always exceed the parents in number— generally to an enormous extent — yet the total number of living organisms in the world does not, and cannot, increase year by year. Opnse* quently, every year, on the average, as many die as are born — plants as Well as animals j and the majority' die premature deaths. They kill each other in a thousand different ways ; they starve each other by some consuming the food that others want ; they are destroyed largely by the powers of Nature — by cold and heat, by rain and storm, by flood and fire, There is thus a perpetual struggle among them which Bhall live and which shall die ; and the struggle is tremendously severe* because so few can possibly remain alive— one in five, one in ten, of tSn only one in a hundred, or even in a thousand. Then comes thequestio'n, Why do some live rather than others i If all the individuals of each species were exactly alike in every "respect, we could only say ib is a' matter of chance. But they are not alike. We find that they vary in many different ways. Some are stronger, some swifter, some hardier in ponstitution, some more cunning. An obscure colour may render concealment more easy for some, keener sight may enable others to disoover prey or escape from an enemy better than their fellows. Among, plants the smallest differences may be useful or the reverse; The earliest and ; strongest shoots may escape, the slug ; their greater vigour may enable them to flower and seed earlier in a wet auttirnn ; plants best armed with spines or hairs may escape being devoured ; those whose flowers are most conspicuous may be sooner fertilised by insects; We c'annbb doubt that, on the whole; any beneficial variation will give the possessors of it a greater probability of living through thetremendous ordeal they have to undergo. There may be something left to chance ; but, on the whole, the fittest will survive.— rA. R. Wallace. The greenfinch ie the first bird about in the mornings beginning to stir at 1.30 a.m. I suppose that the old fable, to the effect that the ostrich' lays her eggs on the sand and leaves them there to be hatched by the sun j -will never dje. A recent .writer in the Globe has phce more exposed the error, but he has:not told,his readers how the eggs are hatched. The fact is that they are hatched by the male, inj the drdinary way, the period of iricubatiohbejhg from S(J to 60 days. A Tiger Frightened /By a Mouse.— A traveller gives the folio wing, anecdote of a tiger kept atj the British Residency at Calcutta :—": — " But ,;wbat annoyed him far more than our poking him with a stick, or tantalising him with shing of: beef or legs of mutton, was introducing a- mouse into his cage. No fine' lady ever exhibited more terror at the sight of a spider than .this- magnifijent royal tiger betrayed on 'seeing a mouse. Our mischievous plan Was to tie the little animal by a string to the end Of a long pole and thrust it elbse to the tiger's hose. The moment he saw it he leaped to the opposite side | and when the mouse was made to run near him he jambed himself into a corner and stood roaring and trembling in such an ecstasy of fear that we were always obliged to desist, in pity to the poor brute. Sometimes we insisted on his passing over the spot where the unconscious little mouse ran backwards and forwards. For a long time, however, we could npt get him to move ; till at length, by the help of a stick, we obliged him to start ; but instead of pacing leisurely across in his den, or of mating a detour to avoid the object of his alarm, he generally took a kind of flying leap, so high as to nearly bring . his back in contact with the roof of his cage."