Indeed the differences of this sort between nearly related animals are literally inexplicable. Much of the difference in temperament between such closely allied species as the American and European bears and wolves is doubtless due to their surroundings and to the instincts they have inherited through many generations; but for much of the variation it is not possible to offer any explanation. In the same way there are certain physical differences for which it is very hard to account, as the same conditions seem to operate in directly reverse ways with different animals. No one can explain the process of natural selection which has resulted in the otter of America being larger than the otter of Europe, while the badger is smaller; in the mink being with us a much stouter animal than its Scandinavian and Russian kinsman, while the reverse is true of our sable or pine marten. No one can say why the European red deer should be a pigmy compared to its giant brother, the American wapiti; why the Old World elk should average smaller in size than the almost indistinguishable New World moose; and yet the bison of Lithuania and the Caucasus be on the whole larger and more formidable than its American cousin. In the same way no one can tell why under like conditions some game, such as the white goat and the spruce grouse, should be tamer than other closely allied species, like the mountain sheep and ruffled grouse. No one can say why on the whole the wolf of Scandinavia and northern Russia should be larger and more dangerous than the average wolf of the Rocky Mountains, while between the bears of the same regions the comparison must be exactly reversed. The difference even among the wolves of different sections of our own country is very notable. It may be true that the species as a whole is rather weaker and less ferocious than the European wolf; but it is certainly not true of the wolves of certain localities. The great timber wolf of the central and northern chains of the Rockies and coast ranges is in every way a more formidable creature than the buffalo wolf of the plains, although they intergrade. The skins and skulls of the wolves of north-western Montana and Washington which I have seen were quite as large and showed quite as stout claws and teeth as the skins and skulls of Russian and Scandinavian wolves, and I believe that these great timber wolves are in every way as formidable as their Old World kinsfolk. However, they live where they come in contact with a population of rifle-bearing frontier hunters, who are very different from European peasants or Asiatic tribesmen; and they have, even when most hungry, a wholesome dread of human beings. Yet I doubt if an unarmed man would be entirely safe should he, while alone in the forest in mid-winter encounter a fair-sized pack of ravenously hungry timber wolves.