Page:The Book of Cats.djvu/90

70 proving that when the external light is wholly excluded, none can be seen in the Cat's eye. For the same reason, the animal, by a change of posture or other means, intercepting the rays, immediately deprives the observer of all light otherwise existing in, or permeating, the room. In this action, when the iris of the eye is completely open, the degree of brilliancy is the greatest; but when the iris is partly contracted, which it always is when the external light, or the light in the room, is increased, then the illumination is more obscure. The internal motions of the animals have also great influence over this luminous appearance, by the contraction and relaxation of the iris dependent upon them. When the animal is alarmed, or first disturbed, it naturally dilates the pupil, and the eye glares; when it is appeased or composed, the pupil contracts, and the light in the eye is no longer seen.

A German savant says, that at the end of each hair of a Cat's whiskers is a sort of bulb of nervous substance, which converts it into a most sensitive feeler. The whiskers are of the greatest use to her when hunting in the dark. The nervous bulbs at the ends of a lion's whiskers are as large as a small pea.