One of the facts discovered by a student of nature is that every part of an animal's body is fitted to perform its special task, and to help the animal live in the surroundings where it finds its home. Notice three ways in which the mole's bodily equipment is fitted to the life he leads.

"Dig" is expressed in every line of the mole's body. Digging is his life-work, and to this Nature has adapted his every organ. His eyes are of no use in this underground life, and so they have dwindled away until externally there is little sign of them. Objects he probably never sees with any distinctness, though he still can tell light from darkness. But he seems to recognize light only to avoid it. In the darkness of his tunnels not only would his eyes be useless, but dirt would be apt to get into them while he is digging; so they are gradually leaving him.

The ears, too, or that part of them that projects from the head, would be in the way. So they have been discarded. The inner and most important part of the ear, however, still remains, and the mole hears quite well.

His most remarkable difference from ordinary animals is in the arms. These are very short, and the hands are broad, hard, and horny, and have very firm claws. When I catch a good, vigorous mole, I find I scarcely have force enough in my thumb and forefinger to hold his front feet together. He can often separate them in spite of all my straining. His other muscles are comparatively weak. The hands have been altered into great shovels, and when he tries to walk over smooth, level ground or on a floor he moves with odd, quick steps, resting on the sides and not on the palms of his hands. He reminds one of a wound-up toy that is held in the air and allowed to run down. But when he gets under the sod, the heaving line that forms over him as he digs shows that there he is in his proper element. Most animals would get dirty leading such a life, but you never see a cleaner animal than the mole. He comes out of the loose earth and squirms about a little, and he is clean. His smooth gray fur, shading to a silvery hue when it is ruffled, is very short and close and exceedingly dry. Indeed I know no animal with a more velvety coat. He would be a delightful pet to handle were it not for his ceaseless wriggling. Then too he carries a strong musky odor. This latter, indeed, is his only defence and I fear it is a poor one. Certainly it does not usually deter a dog from snapping him up. But perhaps it is meant for his friends rather than his foes. Friendly moles may scent each other from afar.

The mole is a reversible machine. He can run forward or backward at will. Probably as a result of this habit, it is wonderful how alike are the two ends of his body, his nose and his tail. Each is slender and each is bare; each is very sensitive, and the tail is just about as long as the nose. I think he uses whichever happens to precede, as a feeler, when he is making his way through his tunnel. For once having made a good big runway, he is very apt to keep on using it through the season. I doubt not he is often forced to travel backwards through his burrow. Then his tail must serve him as an effective guide.

Questions

1. Explain what the author means by saying, "The mole is a reversible machine."

2. How long did it take you to read this selection?