Because they derive their colours from the mucus web on which they are placed, and this differs in various animals.
The composition of scales, observes Dr. Fleming, is similar to that of the cuticle, with the addition of some earthy salts. They appear to be inserted in that layer of the skin, and to resemble it in many of their properties. When rubbed off, they are easily renewed, and frequently experience the same periodical renovations as the cuticle. In reptiles, scales occur on every part of the body, and are placed laterally in some; whilst in others they are imbricated like the slates of a house. In fishes, the scales are usually imbricated, with the epidermis enveloping their base, and the other edge free. They may also be observed on many insects, exhibiting great varieties of form. What are termed feathers on the wings of butterflies, seem to be a variety of scales.
Because they fold their bodies into several undulations, which they unbend all at once, according as they wish to give more or less velocity to their motion.
The body of some serpents is thrown by the muscles into a very rigid state, when irritated; in which condition it breaks into fragments by the slightest stroke.
Because they have very long and bladder-like lungs, and the hinder part of the body and tail is much depressed.
Because, in this attitude, the larger kinds are ready to fall down upon the prey passing beneath, such as deers and antelopes. Such animals are not only retarded by their weight, but incommoded by the foe twisting itself in wreaths round their body, and by contractile efforts crushing it to death.
Because, not only is man their inveterate personal foe, but he receives powerful support from many of the domestic animals which accompany him in his dispersion over the globe. The hog is not afraid to give battle to the most venomous; and, in general, comes off victorious. The goat likewise readily devours the smaller kinds of serpents, and hence the proverb from the Gaelic, " like the goat eating the serpent," - importing a querulous temper in the midst of plenty. - Flemning.
Because they may more readily entice and secure them for food. Such is the opinion of Professor Silli-man, from his observation of two birds who were enticed, and not pursued, by a large black snake in America. " What this fascinating power is," observes the Professor, " whether it be the look or effluvia, or the singing by the vibration of the tail of the snake, or any thing else, I will not attempt to determine - possibly this power may be owing to different causes in different kinds of snakes."
Dr. Hancock, in a recent contribution to Jameson's Journal, however, combats this opinion of the fascination of serpents, by saying, " it is not a faculty of charming or of fascinating, in the usual acceptation of the term, which enables certain serpents to take birds; but, on the contrary, the hideous forms and gestures, which strike the timid animals with impressions of horror, stupefying them with terror, and rendering them unfit for any exertion; especially as those serpents to which has been ascribed the power of fascinating, are among the most terrific of the tribe."