It was the celebrated _ermine_, celebrated for its soft and beautiful fur, so long prized as an ornament for the robes of the rich. It was white all over, with the exception of its tail; and that, for about an inch or so at the tip, was covered with black silky hair. On some parts of the body, too, the white was tinged with a primrose yellow; but this tinge is not found in all animals of this species, as some individuals are pure white. Of course it was now in its winter "robes"; but in the summer it changes to a colour that does not differ much from that of the common weasel.
When Lucien first saw it, it was running along the top of the wreath, and coming from the same direction from which the mouse had come. Now and then it paused awhile, and then ran on again. Lucien observed that it kept its nose to the ground, and as it drew nearer he saw that it was following on the same path which the other had taken. To his astonishment he perceived that it was _trailing the mouse_! Whatever the latter had doubled or made a _détour_, the ermine followed the track; and where the mouse had given one of its long leaps, there the ermine would stop, and, after beating about until it struck the trail again, would resume its onward course at a gallop. Its manoeuvres were exactly like those of a hound upon the fresh trail of a fox!
Lucien now looked abroad to discover the mouse. It was still in sight far off upon the snow, and, as Lucien could see, busily gnawing at the arbutus, quite unconscious that its _greatest_ enemy was so near. I say greatest enemy, for the _Mus leucopus_ is the _natural_ prey of the _Mustela erminea_.
The mouse was soon made aware of the dangerous proximity, but not until the ermine had got within a few feet of it. When it perceived the latter it shrunk, at first, among the leaves of the arbutus; but seeing there would be no protection there--as the other was still springing forward to seize it--it leaped up, and endeavoured to escape by flight. Its flight appeared to be in alternate jumps and runs, but the chase was not a long one. The ermine was as active as a cat, and, after a few skips, its claws were struck into the mouse. There was a short, slender squeak, and then a "crunch," like the cracking of a hazel-nut. This last sound was produced by the teeth of the ermine breaking through the skull of its victim.