SCIENCE SIFTINGS.

Auckland Star, Volume XL, Issue 193, 14 August 1909, Page 16

SCIENCE SIFTINGS.

A ROSE THAT CHANGES COLOUR.

The Chinese, Japanese, and Siamese are said to be peculiarly skilful at botanical feats, the most wonderful achievement of which is known as the "changeable rose." The bloom of this unique effort, says the "Globe," is white in the shade and red in the sunlight. After nightfall or in a dark room this curiosity of the rose family is a pure waxy-white blossom. When transferred to the open air, the transformation imtakes place, the time of the, entire change of the flower from white to red depending on the degree of sunlight and warmth. First the petals take on a kind of faded blue colour, and rapidly change to a faint blush of pink. The pink gradually deepens in hue until one finds that his lily-white of an hour before is as red as the reddest peony that over bloomed. BACTERIA LIGHT. Much of the light commonly known as "phosphorescent" is due to living organisms, generally to microscopic plants or animals. Such is the phoiphorescenee of the sea and of decayed wood. Among the micro-organisms cap able of giving out light as an incident of their life-processes are certain bacteria. On one species a number of interesting experiments have recently been performed by Professor Molisch," of Prague. According to iTiis authority, the light is due to a substance secreted by the organisms, which becomes luminous in the presence of oxygen and water. By cultivating innumerable colonies of "these bacteria side by side, Professor Molisch has made what he calls a "perpetual lamp," with whose light he has been able to take photographs. A BLACKBIRD'S FRIENDLY ACT. Recently, while driving with two friends in Kinross-shire, on the road from Cuthilmuir to the farm of Blairhead (writes a Scotch correspondent on Nature topics), I observed a weasel in close pursuit of a young rabbit. So close were we to the animals that the whip was brought into requisition to separate them, and succeeded so far for a few seconds; but the weasel again got on to the scent of the rabbit, and had almost mode a capture, when a blackbird suddenly swooped down upon the weasel and scared it away. The poor rabbit was seen to be in a sad plight with fear and over-exertion, and it lay down; and as it was considered that it would easily fall a prey to the weasel if the latter again got on its trail, I left the machine, lifted the poor animal, and took it out of the reach of its enemy. AX ANCIENT MINE. At Falun, Sweden, are the headquarters of a mining company with a history so remote that the date of its origin cannot' be definitely fixed. An original purchase deed, dated in the year 1288, has to do uith a sale of stock of the present company, and charters given by King Magnus of Sweden and Norway are dated February 24, 1347. At that time the rights granted by King Magnus' predecessors were referred to as very old. The original business was the manufacture of copper, and the mine at Falun, "Stora Kopparberget" (the great copper mountain), has been continuously worked for nearly 700 years. In this time it has yielded about 500,000 tons of copper, 15.5 tons of silver, and 1.2 tons of gold, the whole representing a value of 1.000,000,000 kroner, or about £55,400----000. BIRDS CAUGHT BY SPIDERS. A curious spider lives in the Ceylon Mountains. It spins a web of bright-yel-low silk, the centre net measures five feet in diameter, and the lines that support it—called guys —measure ten feet or twelve feet. This spider rarely bites or stings, but will do so very severely if any one makes him angry, and, although not poisonous, his jaws are ns strong as a bird's beak. His body is very pretty, bright gold and scarlet underneath, the upper part being of a delicate slate-coloured fur. The webs are so well made that birds the size of larks are often caught, and even lizards have been known to fall victims. This is surprising, for they are so strong that one would think' they could escape from the spider. These poor creatures are caught in n very clever way: The spider first winds the threads firmly round the head of its victim until the prisoner is first blinded and finally choked. In many daik crevices skeletons of birds can be found that have unfortunately fallen into these cruel snares. SIZE OF THE UNIVERSE. If one could start away from the earth and travel steadily in a straight line, what would be find ? Three answers have been made to this question. According to the first", the traveller might go on for ever and would always find stars, although he might cross great void spaces between systems. According to the second, he might keep on for ever, but he would finally pass the outer limit of the material universe, and then he would never meet any more stars. According to the third, if he travelled on for ever, no matter in how perfect a straight line, he would keep coming to the point of starting. The first answer supposes an infinite universe in infinite space; the second supposes a limited universe, but infinite space; and the third means that space itself is limited. This la.st answer, which is given by persons who cannot admit the possibility of infinity, has no evidence for or against it. It is the result of pure speculation.

it is possible, however, to argue about the other two. Those who believe in a limited universe, as probably most astronomers do, say that otherwise the sky would be one uniform blaze of light, for an infinite number of stars would send us an infinite number of light waves, no matter how distant they might be. This assumes that there is no general absorbing medium in space.

A recent contributor to an astronomical magazine. IV. H. S. Monck, believes it is more logical to suppose that much light would be absorbed. In the first place, lie =ays. the stars would ultimately be in one another-; way. Then we know that there .ire many dark celestial bodies. like our own moon, for instance, which wouid -\\st shadows; nnd, 'a'tly. the ether itself may absorb radiiit.oti. He pronounces, therefore, in fa\our of the infinite universe, which man.v sttiJ'.-nts of the suoiec; seem so anxiou* to (.void.