Page:Popular Science Monthly Volume 44.djvu/778

760 the idea among insects; and developments in anthropology teach that savages depend solely for directions upon a skillful use of the external signs of Nature.

All this may be true. It still remains an utter impossibility that a homing pigeon can return from a distance of over a thousand miles if unaided by some special "sense of direction." Such a view is rarely held by a practical pigeon fancier. He knows too well how many birds he loses, even with most careful short-distance training. He has observed that his birds, until they have learned the country, generally consume time enough to enable them to hunt over mile by mile a vast area, and that they can do nothing in a fog or snowstorm, or if blindfolded or hooded. Twenty years ago Leonard wrote as follows: "Some writers, chiefly poets and romancers, would have us believe that the carrier pigeon finds his way home from remote places by a kind of instinct; but this is not the case. Its flight is guided by sight alone. When let loose from confinement, it rises to a great height in the air by a series of constantly enlarging circles until it catches sight of some familiar landmark by which to direct its course."

Had "poets and romancers" continued sole occupants of the field, the following notes would have served no other than the private purpose for which they were taken. As it is, a number of attempts have recently been made by men of high scientific attainments to prove theories of "direction-sense" by feats of the homing pigeon. In general, such attempts are made in line with one or the other of two assumptions. According to the one, "direction-sense" is ascribed to some mysterious, direct, and immediate perception or sensation of location or direction in space. More often it is supposed to be a sort of "dead reckoning" which the organism has become able to keep—that is, the animal has come to have a feeling, definite or vague, as to how long, how fast, and which way it has traveled or has been carried. Two papers may be cited as giving possibly the best expositions of these two views. The one by Prof. Exner adduces evidence to prove the "dead-reckoning" theory; the other, by Prof. Caustier, attempts to establish that of immediate perception. Both agree as to the organ—viz., the membranous labyrinth, especially the semicircular canals.

There is nothing impossible about Exner's explanation. All