Lenz made many interesting experiments. In his work he gives us the result of these, and also what some other German ophiologists had seen and done. He observed how entirely the snake trusted to its tongue in any unusual circumstances; the all-important member was then in ceaseless activity. Confined in a glass jar containing wine or any liquid that the snake did not like, the tongue was ever agitated. Crawling up the side, the tongue was in constant request to feel the glass (as may be often seen at the Zoological Gardens); and on arriving at the top, the head was turned this way and that, and then bent over the edge, as if to make certain that no further obstacle existed; the tongue not for one instant quiet, but exserted sometimes as far forward as the whole length of the head, telling to its owner all that the other senses could not discover. Permitting it to touch his hand, he felt it like the sweep of a thread, so light and delicate. Too fine and flexible to injure any surface, the slightest touch of one or both the tips suffices for intelligence. Nay, sometimes without even touching—that is, without positive contact, but by some subtle sense, it seems to act as guide. When the snake is excited by fear or alarm, or when in a strange place, the activity of the tongue is so great, the vibrations are so rapid, that the eye cannot follow them. It is like the play of electricity. So far from participating in deglutition, the snake withdraws the slender instrument into its sheath, which, while feeding, is safely closed. For this highly-endowed organ is so guarded against injury, that the reptile has not only a place of safety provided, but power to close the mouth of its scabbard, lest dust or other irritating particles should enter. We have only to reflect upon and to observe the habits of snakes to perceive the importance of their tongue to them. For the most part nocturnal, winding their way under tangled masses of vegetation, often in dark caves, holes, crevices, and obscure retreats, with their eyes so placed that they can see neither before nor under them, and with other senses only feebly developed, the tongue with its sensitive papillæ feels its way, and conveys impressions to its owner. Cats have their whiskers to help them in the dark; moles and mice have their quick sense of smell to guide them; all nocturnal animals are gifted in some manner or another, but snakes have only their tongue.