Mule, the hybrid offspring of the male ass and the mare, much used and valued in many parts of the world as a beast of burden. The head, ears, croup, and tail show very distinctly the 'pre-potency' of the ass; but in bulk and stature the mule is nearer the horse, and seems to excel both its parents in sagacity, muscular endurance, sure-footedness, and length of life. Though never much used in Britain (save in some places for tram-cars), it has been common from ancient times in many parts of the East, and is a very important animal in most of the countries round the Mediterranean, and in the mountainous parts of South America. The best European breeds are found in France, Spain, and Italy; those of Kentucky, Missouri, Minnesota, and Mexico are also renowned. The carrier-mules of South America and elsewhere are driven in troops, each led by a bell-bearing old mare. Her they follow with such docility and affection that when the troops mingle in their halting-places they are readily separated by securing the leader. In ancient times mules were often reserved as the peculiar steeds of princes, and they are still used to draw the carriages of Italian cardinals and other ecclesiastical dignitaries. Mules are very surefooted, strong of limb and firm of hoof, clever at passing steep places and sharp turns, easy to please with food. They may be ridden, driven, or used for pack purposes. Their flesh is edible.
The fact that mules are generally sterile has given rise to the common mistake of supposing that sterility is a necessary consequence of hybridisation. Even as regards mules, the females may be successfully crossed by horse or ass, though the more numerous males seem to be constantly sterile. The hinny or companion hybrid of the mule, the offspring of a female ass and a stallion, is not common, and is decidedly inferior in size, strength, and beauty. See ASS, HORSE, HYBRID, CANARY; and for the Spinning-mule, see SPINNING.