Venetian glass.

[Illustration: THE SAND FROM THE MURDERED WOMAN'S PILLOW, MAGNIFIED 25
DIAMETERS.]

"These are Foraminifera!" I exclaimed.

"Yes."

"Then it is not silver sand, after all?"

"Certainly not."

"But what is it, then?"

Thorndyke smiled. "It is a message to us from the deep sea, Jervis;
from the floor of the Eastern Mediterranean."

"And can you read the message?"

"I think I can," he replied, "but I shall know soon, I hope."

I looked down the microscope again, and wondered what message these tiny
shells had conveyed to my friend. Deep-sea sand on a dead woman's
pillow! What could be more incongruous? What possible connection could
there be between this sordid crime in the east of London and the deep
bed of the "tideless sea"?

Meanwhile Thorndyke squeezed out more cement on to the three little
pieces of moulding-wax (which I suspected to be the objects that I had
seen him wrapping up with such care in the hall of the Goldsteins'
house); then, laying one of them down on a glass slide, with its
cemented side uppermost, he stood the other two upright on either side
of it. Finally he squeezed out a fresh load of the thick cement,
apparently to bind the three objects together, and carried the slide
very carefully to a cupboard, where he deposited it, together with the
envelope containing the sand and the slide from the stage of the
microscope.

He was just locking the cupboard when a sharp rat-tat on our knocker
sent him hurriedly to the door. A messenger-boy, standing on the
threshold, held out a dirty envelope.

"Mr. Goldstein kept me a awful long time, sir," said he; "I haven't been
a-loitering."

Thorndyke took the envelope over to the gas-light, and, opening it, drew
forth a sheet of paper, which he scanned quickly and almost eagerly;
and, though his face remained as inscrutable as a mask of stone, I felt
a conviction that the paper had told him something that he wished to
know.

The boy having been sent on his way rejoicing, Thorndyke turned to the
bookshelves, along which he ran his eye thoughtfully until it alighted
on a shabbily-bound volume near one end. This he reached down, and as he
laid it open on the table, I glanced at it, and was surprised to observe
that it was a bi-lingual work, the opposite pages being apparently in
Russian and Hebrew.

"The Old Testament in Russian and Yiddish," he remarked, noting my
surprise. "I am going to get Polton to photograph a couple of sp