had heard somewhere that there is a phosphorescence appearing
during decay of organic substances which once gave rise to the
ancient superstition of "corpse lights" and the will-o'-the-wisp.
It was really due, I knew, to living bacteria. But there surely
had been no time for such micro-organisms to develop, even in the
almost tropic heat of the Novella. Could she have been poisoned by
these phosphorescent bacilli? What was it--a strange new mouth-
malady that had attacked this notorious adventuress and woman of
luxury?

Leslie had flashed up the light again before Craig spoke. We were
all watching him keenly.

"Phosphorus, phosphoric acid, or phosphoric salve," Craig said
slowly, looking eagerly about the room as if in search of
something that would explain it. He caught sight of the envelope
still lying on the dresser. He picked it up, toyed with it, looked
at the top where O'Connor had slit it, then deliberately tore the
flap off the back where it had been glued in sealing the letter.

"Put the light out again," he asked.

Where the thin line of gum was on the back of the flap, in the
darkness there glowed the same sort of brightness that we had seen
in a speck here and there on Blanche Blaisdell's lips and in her
mouth. The truth flashed over me. Some one had placed the stuff,
whatever it was, on the flap of the envelope, knowing that she
must touch her lips to it to seal it She had done so, and the
deadly poison had entered her mouth.