And again, “when a Dog is on the point of springing on his antagonist, he utters a savage growl; the ears are pressed closely backwards, and the upper lip is retracted out of the way of his teeth, especially of his canines.... If a Dog only snarls at another, the lip is generally retracted on one side alone, namely, towards his enemy.” “The feeling of affection of a Dog towards his master is combined with a strong sense of submission, which is akin to fear. Hence Dogs not only lower their bodies and crouch a little as they approach their masters, but sometimes throw themselves on the ground, with their bellies upwards. This is a movement as completely opposite as is possible to any show of resistance.... A pleasurable and excited state of mind, associated with affection, is exhibited by some Dogs in a very peculiar manner, namely, by grinning.”[102] It is extremely interesting to consider the means by which these various expressive movements are produced. If the skin be removed from the head of a Dog, there will be seen, lying beneath it, a quantity of red flesh, intermixed with a good deal of fat and fibrous substance. If this latter be carefully dissected away, the red flesh will be seen to resolve itself into a number of _muscles_, very definitely arranged, and each one designed for some special movement. There are, first of all, muscles which move the eye. One set of fibres closely encircle the aperture of the eyelids, and, when they act, close the eye, either entirely, as in actual sleep, or partially, as in that half sleepy state a Dog loves to be in on a hot afternoon, or before a blazing fire. Another set of eye muscles have an entirely different action to these. They radiate from the eyelids to the surrounding parts of the head, and when they act, “draw back the eyelids from the eyeball, and give a sparkling fierceness to the eye.” From this reason Sir Charles Bell, who first described them, called them _scintillantes_, or sparkling muscles. The ears have a number of muscular bands attached to them, some drawing them forwards, some backwards, others sideways. These are, therefore, highly important muscles, for a Dog hardly passes a moment without moving his ears. We ourselves possess representatives of these muscles, but in an entirely useless state in most persons, very few having the power of moving their ears. Other very important muscles pass from one of the face bones in front of the eye, and are attached to the lip just above the canine teeth. When these act, they draw the lips back from those teeth, thus baring the Dog’s chief weapon, and producing a snarl; they are, therefore, called the _ringentes_, or snarling muscles; and one has only to irritate a Dog to see their effect in altering the animal’s expression. Lastly, there are muscles which draw back the corners of the mouth and produce a sort of grin, an action which seems to be almost normal in the Wolf, but which is also frequently seen in Dogs.