All that was said of the mystery of fox life applies equally to ermine. Why is the ermine of Wisconsin and Minnesota and Dakota a dirty little weasel noted for killing forty chickens in a night, wearing a mahogany-coloured coat with a sulphur strip down his throat, while the ermine of the Arctics is as white as snow, noted for his courage, wearing a spotless coat which kings envy, yes, and take from him? For a long time the learned men who study animal life from museums held that the ermine's coat turned white from the same cause as human hair, from senility and debility and the depleting effect of an intensely trying climate. But the trappers told a different story. They told of baby ermine born in Arctic burrows, in March, April, May, June, while the mother was still in white coat, babies born in an ashy coat something like a mouse-skin that turned to fleecy white within ten days. They told of ermine shedding his brown coat in autumn to display a fresh layer of iron-gray fur that turned sulphur white within a few days. They told of the youngest and smallest and strongest ermine with the softest and whitest coats. That disposed of the senility theory. All the trapper knows is that the whitest ermine is taken when the cold is most intense and most continuous, that just as the cold slackens the ermine coat assumes the sulphur tinges, deepening to russet and brown, and that the whitest ermine instead of showing senility, always displays the most active and courageous sort of deviltry.