"The next night there came a further development. About two thirty a.m.,
I heard my mother's door open, just as on the previous night, and
immediately afterward she rapped sharply, on the banister, as it seemed
to me. I stopped my work and called up that I would not be long. As she
made no reply, and I did not hear her go back to bed, I had a quick sense
of wonder whether she might not be doing it in her sleep, after all, just
as I had said.

"With the thought, I stood up, and taking the lamp from the table, began
to go toward the door, which was open into the passage. It was then I got
a sudden nasty sort of thrill; for it came to me, all at once, that my
mother never knocked, when I sat up too late; she always called. You will
understand I was not really frightened in any way; only vaguely uneasy,
and pretty sure she must really be doing the thing in her sleep.

"I went quickly up the stairs, and when I came to the top, my mother was
not there; but her door was open. I had a bewildered sense though
believing she must have gone quietly back to bed, without my hearing
her. I entered her room and found her sleeping quietly and naturally; for
the vague sense of trouble in me was sufficiently strong to make me go
over to look at her.

"When I was sure that she was perfectly right in every way, I was still
a little bothered; but much more inclined to think my suspicion correct
and that she had gone quietly back to bed in her sleep, without knowing
what she had been doing. This was the most reasonable thing to think, as
you must see.

"And then it came to me, suddenly, that vague, queer, mildewy smell in