Like the chicken's gizzard the gizzard of the earthworm is lined with a thick, tough membrane, and it has muscles--such muscles! There are two sets of these muscles and they cross each other somewhat like the warp and woof of the cloth in your clothes. The muscles that run lengthwise are not so very strong, for all they have to do is to help the earthworm swallow, but the muscles that run around the gizzard are wonderfully strong. They are about ten times as thick as the other muscles. One of Mr. Earthworm's French biographers[10] calls these muscles "veritable armatures"; that is, freely translated, "veritable hoops of steel." [10] When you study French, if you want to read this book--like most French works on science it is very interesting--ask for Perrier's "Organization des Lumbricus Terrestris." I said, in the second paragraph above this, that worms swallow grains of sand and stones to help their digestions, as chickens do. But the earthworm saves time, for he takes the stones with his meals; just as some Englishmen, fat old squires, when they get along in years, or for any other reason are a little weak in their digestive regions--keep pepsin on the table with the pepper and salt. And--believe it or not--the earthworm actually makes his _own_ millstones sometimes! The chalk in the chalky fluid of the glands that help him digest his meals frequently hardens into little grains in grinding the food. It's almost as if the saliva in our mouths, in addition to acting directly on the food, also made a new set of teeth for us! Suppose we had a stomach like the earthworm, wouldn't it be fun? We could digest the biggest dinners at Thanksgiving and Christmas and picnics and birthdays. We could even eat apples without waiting for them to get quite ripe. Haven't you done it to your sorrow? And no stomachache and no mince-pie nightmares! WHY THE EARTHWORM NEVER HAS NIGHTMARES By the way, the earthworm, although he has his troubles like the rest of us, never _has_ nightmares. For one thing he has that stomach[11] and--a still better reason, perhaps--he never sleeps at night. Like the moths and the bats and the burglars and members of Parliament, he makes night his busy day. [11] Just listen to this: "Worms," says Mr. Darwin, in that remarkable book of his, "are indifferent to very sharp objects, even rose thorns and small splinters of glass." And, in other ways, while he is so much like the rest of us worms of the dust, his life differs from that of most people. For instance, he not only works by night while we work by day, and works underground while we work on top, but he takes his vacation in the Winter while we take ours in Summer. In that respect Mr. Earthworm is like the millionaires at Palm Beach; for in Winter he, too, goes in the direction we call south on the map--that is to say _down_. But, as you say, it takes all kinds of people to make a world; including earthworms and millionaires!