Page:Popular Science Monthly Volume 3.djvu/538

522 animals whereby they are infallibly guided on their return homeward from distant places. Mr. Wallace thinks that this faculty is, in dogs at least, simply a very acute sense of smell. According to him, the dog "takes notes by the way" of the various odors he passes through, and finds his way back by taking the links of this chain in reversed order. But this explanation is open to very serious difficulties, and Mr. Darwin's simpler theory will appear far preferable.

Indeed, Mr. Wallace's theory seems hardly broad enough to account for more than a very inconsiderable fraction of the phenomena which it is proposed to explain. For dogs, cats, horses, and the like, it may be good enough, until a better theory is found. But what possible application could it have to such a case as the following, which is given by Mr. Edward W. Cox, on the high authority of Mr. Robert Fox, of Falmouth? "The fishermen of Falmouth," writes Mr. Cox, "catch their crabs off the Lizard Rocks, and they are brought into the harbor at Falmouth alive, and impounded in a box for sale, the shells being branded with marks by which every man knows his own fish. The place where the box is sunk is four miles from the entrance to the harbor, and that is above seven miles from the place where they are caught. One of these boxes was broken; the branded crabs escaped, and two or three days afterward they were caught again by the fishermen at the Lizard Rocks. They had been carried to Falmouth in a boat. To regain their home they had first to find their way to the mouth of the harbor, and, when there, how did they know whether to steer to the right or to the left, and to travel seven miles to their native rocks?"

It is unphilosophical to set up many different hypotheses, where one would answer. For this reason we are inclined to accept Mr Darwin's explanation of the phenomenon in question, rather than Mr. Wallace's. Mr. Darwin, it will be seen, aims at bringing all the phenomena under one general law, that of a Faculty of Direction, as it may be called. In confirmation of this hypothesis, the veteran naturalist quotes from Von Wrangell's account of his expedition to North Siberia, as to the "wonderful manner in which the natives kept a true course toward a particular spot, while passing for a considerable distance through hummocky ice, with incessant changes of direction, and with no guide in the heavens, or on the frozen sea." Even with the aid of a compass, an experienced surveyor in Von Wrangell's party failed to do what these savages easily effected. Mr. Darwin says the Siberians keep a sort of "dead reckoning" of their course, correcting their deviations partly by eyesight, partly also, perhaps, by a sense of muscular movement, as some men can, even with bandaged eyes, proceed for a short distance in a straight line, turn at right angles, or even back again. Some persons are "turned around," as we say, far more easily than others. Such persons would very easily lose their way, were they to attempt traversing an extensive forest, for instance. Mr. Darwin is inclined to think that some part of the brain is "specialized for the function of direction." If that is the case, it is very natural to suppose that this specialization may be more marked in beasts and savages than in civilized man, as the former have more constant need to exercise the faculty of direction than the latter. Mr. Darwin closes his communication on this subject by citing a case from Audubon, where the faculty of direction was egregiously at fault. The great ornithologist kept a pinioned wild-goose in confinement, and, when the time for migrating came, the bird escaped. Instead of proceeding due southward, as it should have done, the poor creature began its long journey on foot, travelling due northward, exactly the wrong direction.

Habits of the Porpoise.—The behavior of the porpoise in the Brighton (England) Aquarium has been studied with warm interest, by Mr. Henry Lee, F. L. S., who communicates to Land and Water an interesting account of his observations. Mr. Lee had previously enjoyed frequent opportunities of watching the porpoise at sea, whether from the bow of a steamer, or over the gunwale of a boat, but an uninterrupted, broadside view of all its movements was, for him, "a new, delightful, heart-stirring sight, and one often longed for." He observed that the tail, with its flat blade spread out