The brown rat has persistently accompanied man all over the world. Millions have been spent in fighting him and the bubonic-plague flea that he cheerfully carries in his offensive fur. For him no place _that contains food_ is too hot or too cold, too wet or too dry. Many old sailors claim to believe that rats will desert at the dock an outward-bound ship that is fated to be lost at sea; but that certificate of superhuman foreknowledge needs a backing of evidence before it can be accepted. Of all wild animals, rats do the greatest number of "impossible" things. We have matched our wits against rat cunning until a madhouse yawned before us. Twice in my life all my traps and poisons have utterly failed, and left me faintly asking: _Are_ rats possessed of occult powers? Once the answer to that was furnished by an old he-one who left his tail in my steel trap, but a little later _caught himself_ in a trap-like space in the back of the family aeolian, and ignominiously died there,--a victim of his own error in judging distances without a tape line. Tomes might be written about the minds and manners of the brown rat, setting forth in detail its wonderful intelligence in quickly getting wise to new food, new shelter, new traps and new poisons. Six dead rats are, as a rule, sufficient to put any _new_ trap out of business; but poisons and infections go farther before being found out. [Footnote: For home use, my best rat weapon is rough-on-rats, generously mixed with butter and spread liberally on very thin slices of bread. It has served me well in effecting clearances.] The championship for keen strategy in self-preservation belongs to the musk-oxen for their wolf-proof circle of heads and horns. Every musk-ox herd is a mutual benefit life insurance company. When a gaunt and hungry wolf-pack appears, the adult bull and cow musk-oxen at once form a close circle, with the calves and young stock in the centre. That deadly ring of lowered heads and sharp horns, all hung precisely right to puncture and deflate hostile wolves, is impregnable to fang and claw. The arctic wolves know this well. Mr. Stefansson says it is the settled habit of wolf packs of Banks Land to pass musk-ox herds without even provoking them to "fall in" for defense. Judging by the facts that Charles L. Smith and the Norboe brothers related to Mr. Phillips and me around our camp-fires in the Canadian Rockies, the wolverine is one of the most cunning wild animals of all North America. This is a large order; for the gray wolf and grizzly bear are strong candidates for honors in that contest.