"Then I can play with Henrietta? And father wouldn't mind, do you think? And your head can't be hurting, mother, because you just laughed right out." CHAPTER IV Professor Ladue again sat on the floor of his room before the skeleton of his lizard, absent-mindedly fingering a bone. Now and then he looked out of the window at the great tree; at that particular spot in the great tree upon which his daughter had been seated, one morning, not so very long before. He may have had a half-formed wish that he might again discover her there. But I do not know what half-formed wishes he had, concerning the tree, his daughter, or anything else. At all events, Sally did not appear in the tree. Had not he expressed disapproval of that very performance? He could trust her. Perhaps, with a dim consciousness of that fact, and, perhaps, with a certain disappointment that she was to be trusted so implicitly,--she bore, in that respect, not the most remote resemblance to her father,--the professor sighed. Then, still holding the bone which bothered him, he went to his desk. There was a bone missing--possibly more than one--and he would try to draw the missing bone. He had scarcely got to work when there was a knock at his door. It was a firm knock, but not loud, expressing a quiet determination. Professor Ladue seemed to know that knock. He seemed, almost, as if he had been waiting for it. "Come!" he cried, with an alacrity which would not have been expected of him. He pushed back his drawing-board and Sally came in. "Ah, Miss Ladue!" he cried, with a certain spurious gayety which concealed--something. I don't know what it concealed, and neither did Sally, although she knew well enough that there was something behind it. She feared that it was anxiety behind it, and she feared the cause of that anxiety. "And what," continued the Professor, "can we do for Miss Ladue to-day? Will she have more about this lizard of mine?" Sally's eyes lighted up and she smiled. "I should like that very much, father, thank you. But I can't, this morning, for I'm taking care of Charlie." "And is Charlie concealed somewhere about you? Possibly you have him in your pocket?" Sally giggled. "Charlie's tied to a tree." "Tied to a tree! Does he submit gracefully?" "He's an alligator; down by the wall, you know." "Ah!" exclaimed the professor. "I am illumined. Do you think it is quite for the safety of the passers-by to keep an alligator so close to the road?" Sally giggled again. "Yes," she returned, "if I'm not gone too long. I came on an errand." Professor Ladue lost somewhat of his gayety. "State your errand, Sally. I hope--" But the professor neglected to state what he had hoped. Sally stated her errand with her customary directness. "Mother wants me to go to dancing-school. Can I?"