"Ada Nansen or Ruth Gladys Royal might do it to plague Libbie," said Betty slowly. "They don't like any of our crowd, and Libbie is so good at French she turns Ada green with envy. The more I think of it, the surer I am it is Ada. Ruth doesn't dislike any one actively enough to exert herself."
"Ada Nansen?" repeated Bob. "Isn't she that girl we saw on the train and who plumped herself down in my seat? I thought so—I remember you told me. Well, from the sidelight I have on her character, I believe she is the one at the bottom of this. That will explain, too, why you never catch any one digging up the bottle—she knows exactly when you are busy and when you are not."
"Bottle!" said Betty explosively, to Bob's amazement. "Oh, Bob! this morning Miss Jessup was talking to us about association of ideas, and she asked Ada what bee meant to her. We thought she'd say 'honey,' of course, but she said 'bottle.' Doesn't that show——"
"I should say it did!" Bob's voice was eager. "She took it for the letter 'B' and bottle was in her mind. You may depend upon it, that girl is at the back of all this fuss! Gee, when I've nothing else to do, I'm going to study up on this association of ideas stuff."
"You don't need it—you can get at things with-
