He had difficulty in keeping still.

From the lines of chairs along the walls and from doors and alcoves rushed the gay-colored throng to leap, to close, to step, to rock and sway, until the floor was full of a moving mass of life.
The first half-dozen couples Lane studied all danced more or less as Helen and Swann had, that day in Helen's studio.

Then, by way of a remarkable contrast, there passed two young people who danced decently.

Lane descried his sister Lorna in the throng, and when she and her partner came round in the giddy circle, Lane saw that she wiggled and toddled like the others.

Lane, as she passed him, caught a glance of her eyes, flashing, reproachful, furious, directed at some one across her partner's shoulder.