he shelf behind the door. On it were two flat china
candlesticks, in one of which I had happened to notice, as we came in, a
short end of candle lying in the tray, and I now looked to see if that
was what Thorndyke had annexed; but it was still there.

I followed my colleague out into the street, and for some time we walked
on without speaking. "You guessed what the sergeant had in that paper,
of course," said Thorndyke at length.

"Yes. It was the hair from the dead woman's hand; and I thought that he
had much better have left it there."

"Undoubtedly. But that is the way in which well-meaning policemen
destroy valuable evidence. Not that it matters much in this particular
instance; but it might have been a fatal mistake."

"Do you intend to take any active part in this case?" I asked.

"That depends on circumstances. I have collected some evidence, but what
it is worth I don't yet know. Neither do I know whether the police have
observed the same set of facts; but I need not say that I shall do
anything that seems necessary to assist the authorities. That is a
matter of common citizenship."

The inroads made upon our time by the morning's adventures made it
necessary that we should go each about his respective business without
delay; so, after a perfunctory lunch at a tea-shop, we separated, and I
did not see my colleague again until the day's work was finished, and I
turned into our chambers just before dinner-time.

Here I found Thorndyke seated at the table, and evidently full of
business. A microscope stood close by, with a condenser throwing a spot
of light on to a pinch of powder that had been sprinkled on to the
slide; his collecting-box lay open before him, and he was engaged,
rather mysteriously, in squeezing a thick white cement from a tube on to
three little pieces of moulding-wax.

"Useful stuff, this Fortafix," he remarked; "it makes excellent casts,
and saves the trouble and mess of mixing plaster, which is a
consideration for small work like this. By the way, if you want to know
what was on that poor girl's pillow, just take a peep through the
microscope. It is rather a pretty specimen."

I stepped across, and applied my eye to the instrument. The specimen
was, indeed, pretty in more than a technical sense. Mingled with
crystalline grains of quartz, glassy spicules, and water-worn fragments
of coral, were a number of lovely little shells, some of the texture of
fine porcelain, others like blown