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Show Keen Sense of Hearing Warns Bats of Danger A great naturalist, the Abbe Spalan- zani, decided to make experiments upon bats with a view to discovering the source of their uncanny powers of steering. He built a large aviary across which he suspended wires, strings, and all kinds of obstacles. In this he turned loose a number of bats, which flew hither and thither just as they would do in the open air with never a single collision. Deciding to go farther, he obtained a number of bats which were completely blind. When these were Introduced Into the cage they flew just like the others, and were equally skillful In avoiding obstacles. ob-stacles. The explanation given by some scientists sci-entists is that the bat's wings, which are provided with a strange network of delicate nerves, act as sounding-boards, sounding-boards, and that by the increased air pressure on them as he approaches an obstacle, he receives an automatic warning and turns away. But there is another explanation. Whilst bats are flying they are never silent. All the time they utter a sharp cry. Why should the bat squeak continuously as he flies in pursuit pur-suit of his prey? It is not to attract at-tract others of the species, for, though bats live in flocks, each hunts individually. indi-vidually. The bat squeaks In order that his ears may give him warning of the presence of an obstacle In his line of flight. His hearing Is extraordinarily acute. If he approaches a wire or some other source of danger the sound of his own squeaks is thrown back to him by It like an echo. His ears hear tfe change of sound and detect de-tect the direction from which the ocho comes. |