THE NATURALIST.

Otago Witness, Issue 1895, 16 March 1888, Page 36

THE NATURALIST.

The Bird of Lofty Plight.

Darwin, while watching long the lofty flight of the Lammergsier's American cousin, the condor, in its great circling swsep_ at enormous altitudes above the Chilian plains, wondered ac the bird's power of thus sailing, hour after hour, in those great _ sweeping circles, without any apparent motion of the outspread wings. He arrived at the probably correct solution of the puzzle— a puzzle which has bothered a good many other observers in watching the spiral flight of the eagle and the red-failed hawk. The extended wings gave not a single flap, but seemed to form the fulcrum on which the movements of the rest of the great bird— bis neck, body and tail— acted. "If the bird wished to descend, the wings were for a moment collapsed ; and when again expanded, with an altered inclination, the momentum gained by the descent seemed to urge the bird upward, with the even and steady movement of a paper kite." There is something attractive in such a spectacle. The condor is known to soar far above the loftiest peaks of the Andes, which lift their snowy tops to elevations four miles above the sea ; indeed, it is known to rise six miles in vertical height— far above all ordinary clouds— and there, in that rarified region, in which human life could not exist, his eagle eye surveys the world below in search of his prey, and finds in those silent spaces of the sky his native air. That a company of three or four condors can, and actually have, more than once run down and killed one of the wild cattle of the Pampas, first blinding the animal by destroying his sight, before killing him and dininp: off his carcass, is a fact which is said to have been witnessed by those who have related the story.— Hartford Times.

Hunting Water With a baboon.— if when upon a long hunt or journey the Kaffir be unable for a long time to find water, he sometimes avails himself of the instinct of one of those animals which he frequently keeps in a domesticated state— the baboon, or the chacma. The baboon takes the lead of the party, being attached to a long rope, and allowed to run about as it likes. When it comes to a root of babiana, it is held back until the precious vegetable can be taken entire out of the ground, but in order to stimulate the animal to further exertions it is allowed to eat a root now and then. The search for water is conducted in a, similar manner. The wretched baboon is intentionally kept without drink until it is half mad with thirst and is then led by a cord as before mentioned. By what signs that animal is guided no one can even conjecture, but if water is in the neighbourhood the baboon is sure to find it, A Curious Discovery.— A Kussian physician, Dr S. Th. Stein, reports some remarkable experiments, in which he has induced cataract in the eyes of young porpoises by subjecting them to the continuous vibrations of a tuning fork for 12 to 24 hours, or for a much less time, when the animals were deprived of the power of hearing. The cataract goon disappeared on removing the exciting cause, and could be renewed. The phenomenon has not been satisfactorily explained. The Migration of British Birds.— Twice every year a great number of birds come to and go from the British Isles. This is what is called their " migration. ' Many leave on the approach of winter and return next spring or summer with the warm weather. There are, however, several kinds that come to England for the winter from still colder countries where the food supply is scarce, Some interesting facts have been noticed about these immense flights. When north and east winds blow the birds fly high, and low when the wind is in the south and west. During fog rain, and snow they fly very low, and often lose their way. Ihey frequently strike themselves against the lanterns of lighthouses, and then they will fly round and round the lights till daylight sends them on their journey again. J?he time during which the migration lasts varies with the different kinds of birds. In some kinds it is completed in four or five weeks while others take months and even half a'year to do their flitting. The rate at which they travel, too, varies. It is estimated that the woodcock, for example, does 52 miles an hour, and can keep up this rate for 10 or 12 hours. Nature's Provision.— Mr Poulton has published a further account of his experiments on the very remarkable power that certain larvce possess of adjusting their colour to imitate that of their surroundings. There can be no doubt now of the fact. Hitherto some :iaturalists have been inclined to think that a difference of food would account for the strange differences of colour, but Mr Poulton shows that certain larvse when fed on exactly the same food develop totally different colours according to the colour o£ their habitat. The property of the nervous system which enables such an tidiustment to be effected is one whose further study ought to throw considerable light on the way in which nerves respond to external stimuli. SOARING Birds.— An interesting contribution to the question of the soaring of birds was made recently by Professor W. P. Trow, bridge to the American Academy of Sciences. It appears that his son has discovered that birds of prey and some others have the power of locking together those parts of the wing holding the extended feathers, so that the action of the air extends the elbow, and the wings can be kept in the position for an indefinite period without any expenditure of muscular exertion on the part of the bird. Professor Trowbridge expressed the opinion that it is possible for a bird to sleep on the wing, and Professor J. S. Newberry said that he once shot a bird which came slowly to the ground with its wings extended, but quite dead. He believed the discovery of Mr Trowbridge explained what he had never previously been able to account for.— English Mechanic.