He kept that book under lock and key. There was not an urchin in school but was perishing to have a glimpse of it, but the chance never came. Every boy and girl had a theory about the nature of that book; but no two theories were alike, and there was no way of getting at the facts in the case. Now, as Becky was passing by the desk, which stood near the door, she noticed that the key was in the lock! It was a precious moment. She glanced around; found herself alone, and the next instant she had the book in her hands. The title-page -- Professor Somebody's ANATOMY -- carried no information to her mind; so she began to turn the leaves. She came at once upon a handsomely engraved and colored frontispiece -- a human figure, stark naked. At that moment a shadow fell on the page and Tom Sawyer stepped in at the door and caught a glimpse of the picture. Becky snatched at the book to close it, and had the hard luck to tear the pictured page half down the middle. She thrust the volume into the desk, turned the key, and burst out crying with shame and vexation.