Science Siftings

New Zealand Tablet, 20 August 1908, Page 35

Science Siftings

BY 'VOLT

• ' - Sensitive Plants.'. - r " r There are plants so sensitive that 'if, when standing* by them* you should .-suddenly .put up your umbrella or sunshade, it would be quite sufficient to cause them instantly to close together their leaflets and, .turn _.down their leaf-stalks, just as ifthey were" startledTand alarmed "by the movement. Indeed,, on a -sunny ' day, when the- temperature is _sufficiently high, you need not make, even "so decided a movement ; merely your shadow coming in contact with their leaves will often cause them to fall slightly. • _ v ' „."._"-' -, - : - A Useful Tree. , The carnahuba palm of -Brazil is the— world's most useful tree. A^ department store__tree»_#.ou might well -call -it,.'" for it gives everything from medicine to cattle -feed. . Its , roots make a very, valuable drug, a blood purifier that is prescribed a good deal in the spring. Its timber -takes a high polish, and is i.i demand" among cabinetmakers for fine work. The sap becomes wine* or vinegar, according to the way if is prepared; and" starch and -sugar are also, obtained "from this sap. " The fruit; of. the tree is a cattle food ; the nut is a good coffee substitute ; -the pith makes corks. There, can you beat it — medicine, sugar, coffee, starch, wine, corks, cattle food, lumber and vinegar, all from "this -one tree, the carnahuba. palm ? -' , One of Nature's -Laws. - . .. - Let us observe a law common to all trees". - -First, -neither the stems nor boughs of the maple, elm, or oak taper except at the point where they fork. Whenever a stem sends forth a - branch and a branch sends off a smaller bough, bud or- stem,",, they remain the same in diameter, ' and the original stenT will • increase rather than -diminish until its next branch starts. No bough, branch, or stem ever nairows near ils "extremity except where it parts with a .portion of its substance, by sending 01T another branch or stem. All trees are alike in this respect, and. if all , the bough-;, branches, stems, buds, and blossoms wera combined.- and .united without loss of space they would form a~ round log the same in ' size and diameter as -, the trunk; from which- they spring. This is one of nature's" imperative laws, and never fails to prove true. Arabic Figures". - - - Our figures are called Arabic not because they originated in Arabia— they came to Arabia from Hindustan— but because they were introduced into Spain by the Moors, Arabs, or their conquerors, -and thence found their way into the rest of Europe. Nothing absolutely certain is known as to their origin, and theci has been a good deal of controversy resulting over- it, one of , the two- following theories probably being the correct one :— As - excellent geometricians, they^composed the written "number, out of geometrical figures. One has only one angle, two has. twn, ■three, etc. ; o, a circle, has none. Again, it is argued that the figures were composed of right angles and squares, .Jhe~number of lines used indicating the number to be noted. There is one line in i, and there are three in 3, seven in 7, etc- The Greeks and Romans had systems totally different from. ours,, and -which" made long calculations almost impossible'; therefore,. it seems likely that the mathematicians of old had knowledge of what are now. called Arabic figuras. The Voraciousness of Plants'. 1 . - -The voraciousness of plants was a subject touched" on by Mr. G..M. Thomson -during a lecture/at Dunedin the other day. He spoke of a species which in many places grows- in profusion about the Bluff, and which displays long, tempting-looking leaves or branches as a resting : place for flies. . Immediately a fly rests •there, -however, he becomes, a fixture, by -reason of a glutinous substance which the plant has upon its leaves and branches Finally the fly is engulfed in the leaf, for the strange thing, immediately it has him firmly, rolls itself around him, discharges upon him a secretion not unlike animal saliva, and in, a very short time assimilates him. When the plant unrolls again to await another' victim, all that remains of theunfortunate.insect is his wings. The remainder" of him constitutes 'part of- the plant Mr. Thomson said that he fed. this queers-plant" on pieced of beef and mutton, which* it accepted eagerly^ it Would not take a stone, however, or anything yielding no , sustenance.- It took" a piece of cheese, 'but,' said the lecturer, 'it suffered from an | acute fit of indigestion.' Another plant he-described .as common^ to -New Zealand has small holes around its base, into which insects creep for shelter. By these means the hungry 'vegetable - catches its victim,, asphyxiates and slowly, digests him