“The creature we call the spiral snail—isn’t it a slug that finds an empty shell and lives in it?” asked Emile.
“No, my friend; a slug remains always a slug without becoming a snail; that is to say, it never has a shell. The snail, on the contrary, is born with a tiny shell that grows little by little as the snail grows. The empty shells you find in the country have had their inhabitants, which are now dead and turned to dust, only their houses remaining.”
“A slug and a snail without its shell are very much alike.”
“Both are mollusks. There are mollusks that do not make shells, the slug for example; others that do make them, such as the snails, the Paludinidæ, and the cassididæ.”
“And of what does the snail make its house?”
“Of its own substance, my little friend; it sweats the materials for its house.”
“I don’t understand.”
“Don’t you make your teeth, so white, shiny, and all in a row? From time to time a new one pushes through, without your giving it any thought. It does it by itself. These beautiful teeth are of very hard stone. Where does that stone come from? From your own substance, it is clear. Our gums sweat stone which fashions itself into teeth. So the snail’s house is built. The little creature sweats the stone that shapes itself into a graceful shell.”
“But to arrange stones one on another and make houses of them you need masons. The snail’s house is made without masons.”
“When I say it is done by itself, I do not mean that the stone has the faculty of making itself into a shell. You never see rubble piling itself unaided into a wall. God, the Father of all things, willed that the stone should arrange itself in a mother-of-pearl palace to serve as a dwelling for the poor animal, brother to the slug, and it is accomplished according to His will. In like manner He told the stone to grow up into beautiful teeth from the depths of the rosy gums of little boys and girls, and it is done as He willed.”