few individuals have preceded the main body, and that during the first autumn the numbers are never large, but, after a winter spent beneath the snow, they begin to breed with the first days of summer, and thus develop the extraordinary multitude which is, as it well may be, the astonishment and terror of the country. It appears, then, that excessive reproduction is rather the result than the cause of migration. It has also been suggested that the course taken by the lemmings follows the natural declivities of the country, but a reference to the maps will show that in that case nearly all the Norwegian migrations should take a southerly route, which is by no means the case. On the contrary, westward at Heimdalen means across a rapid river, over a wide lake, and up a steep, rocky, and snowy mountain, and this is the course which is followed. Now, this ends eventually in the ocean, and thus we are again landed at the question from which we set out. After all, it is not the power of direction which is so remarkable; this is a faculty possessed by many animals, and by man himself in a savage state. A young dog which I took from England, and then from my home in Vaage by a path to Heimdalen, a distance of forty-six miles, ran back the next morning by a direct route of his own, crossing three rapid rivers and much snow, and accomplishing the distance in six hours, without the vestige of a path. This same dog afterward repeated the feat, but followed the path, and took two days in reaching his destination, hindered and not aided, as I believe, by his experience. Herr Palmén, indeed, says, "Experience guides migration, and the older migrants guide the younger," like one of Mr. Cook's personally-conducted tours. This obviously cannot be the case with the lemmings.
It is now generally admitted that instinct is merely inherited experience, and is, therefore, primarily calculated to benefit the species, unless, indeed, circumstances have changed meanwhile more rapidly than the structures to which the phenomena of instinct are due. Now, the lemmings during their wanderings pass through a land of milk and honey, where, if their instincts could be appeased, they might well take up a permanent abode; and yet they pass on, while their congener, the field-vole, remains in quiet possession of the quarters from which he was temporarily ousted. It is, indeed, almost as strange a sight to see the holes, the deeply-grooved runs, and the heaps of refuse, of these restless creatures, which have passed away but yesterday, as it is to see the fields suddenly become alive with a new and boisterous tenant, who, like another Ishmael, has the hand of all men against him.
Now, if we compare the migration of the lemmings with that of our more familiar swallows, we find that the latter obviously seek a more genial climate and more abundant food, returning to us as surely as summer itself; nor do they ever, so far as I know, breed on their passage. The swifts, which stay but a short time with us, remain in
