"Because they keep _dogs_!" said Bankey, twittering with glee; "two nice dogs. One big and buff and bushy, with a much finer tail than the proudest fox you ever saw; and the other small and white with some dark spots, and as quick as a squirrel. This one has a short tail that sticks up like a Wren's and a nose like a weasel; one ear stands up and the other hangs down; and he has a _terrible_ wink in one eye. Even a poor little Bank Swallow knows that where one of _these_ dogs lives the Bird People need not fear either cats or rats!" "I love dogs," said the black-and-white Downy Woodpecker, running up a telegraph pole in search of grubs; "dogs have bones to eat and I like to pick bones, especially in winter." "Me too," chimed in the Nuthatch, who walks chiefly head down and wears a fashionable white vest and black necktie with a gray coat; "and sometimes they leave bits of fat about. Yes, dogs are very friendly things indeed." Then a joyful murmur ran all along the wires, and Farmer Griggs, who was driving past, said to himself, "Powerful lot of 'lectricity on to-day; should think them Swallers would get shock't and kil't." But it was only the birds whispering together; agreeing to return to their old haunts at Orchard Farm and give the House Children a chance to learn that there are no such things as "common" birds. CHAPTER II THE DOCTOR'S WONDER ROOM Nathaniel and Theodora, who were called Nat and Dodo for short, were standing in the hallway outside Dr. Hunter's door, engaged in a very lively argument. "I say birds are animals," blustered Nat, pounding his fists together after a fashion of his own. "And I'm as sure as anything that they _can't_ be," persisted Dodo, "because they have feathers, and nothing else has." "That doesn't prove anything. Everything that lives and grows is either an animal or a vegetable. Do you think that birds grow like potatoes and are dug out of the ground, or come off trees like apples?" And Nat gave himself an air of great wisdom, such as brothers are apt to wear when they are in the fifth reader, and their sisters are only in the third. "But isn't there anything besides animals and vegetables that they might be? Perhaps they are minerals," said Dodo, brightening up as she thought of the word. "Oh! oh! what a stupid you are, Dodo! Minerals! Why those are rocks and such things, that can't move and don't live." Nat laughed rather rudely, and, putting his hands in his pockets, began to whistle. "I think you might tell me _what_ kind of an animal a bird is, and why it has feathers and can fly, instead of laughing," said Dodo in a shaky voice; for her feelings were very tender and she remembered too late what minerals are. "Yes, tell her, Nat," said Olive, who came through the hall just then. "Are you holding your knowledge tight in your pockets, or whistling to keep from telling it?"