animals always change; that in those from intermediate latitudes the change is incomplete, while those from farther south do not change at all.” The advantage of the change to the animal is manifest; its colour becomes that of the snow over which it travels in pursuit of game, so that it is less easily seen and avoided. Unfortunately for it, however, a similar “protective colouring” is adopted by some of its victims. [Illustration: WEASEL (1) AND ERMINE (2) IN THEIR WINTER CLOTHING.] The habits of the Stoat resemble those of the Weasel; it is dangerous both to the sheep-fold and to the poultry-yard, but partly atones for its poaching by the immense number of Rats and Mice it is capable of destroying. Audubon relates that he “once placed a half-domesticated Ermine in an outhouse infested with Rats, shutting up the holes on the outside to prevent their escape. The little animal soon commenced its work of destruction. The squeaking of the Rats was heard throughout the day. In the evening it came out, licking its mouth, and seemed like a hound after a long chase, much fatigued. A board of the floor was raised to enable us to ascertain the result of our experiment, and an immense number of Rats were observed, which, although they had been killed in different parts of the building, had been dragged together, forming a compact heap.” Both Weasel and Ermine are found over the greater part of Northern Europe, Asia, and America. THE POLECAT.[172] In form this animal does not differ very markedly from the Marten, except for the fact that its head is broader, its snout blunter, and its tail very much shorter: the latter being about five and a half inches, while the head and body together are nearly a foot and a half long. The neck is considerably shorter, and the body stouter than in the Weasel and Stoat. The fur is made up of hairs of two kinds, the shorter woolly and of a yellowish colour, the longer black or brownish-black and shining. One of its most marked characters is its horrible stench. This is produced, like the scent of the Civets, in a pair of glands near the root of the tail, which secrete a yellowish creamy substance of the most fetid character. [Illustration: SKULL OF POLECAT. (_After Coues._)] The Polecat is also known as the Fitchet (Fitchew of Shakspere), Foumart, or Foulimart: the latter names are said to be a contraction of “Foul Marten,” thus distinguishing it from the Common or Sweet Marten, which is a comparatively inodorous animal. The name Polecat is probably a contraction of Polish Cat.