ed-up
windows! Hang it all, Petrie! one cannot sleep in a room hermetically
sealed, in weather like this! It's positively Burmese; and although I
can stand tropical heat, curiously enough the heat of London gets me
down almost immediately."

"The humidity; that's easily understood. But you'll have to put up with
it in the future. After nightfall our windows must be closed entirely,
Smith."

Nayland Smith knocked out his pipe upon the side of the fireplace. The
bowl sizzled furiously, but without delay he stuffed broad-cut mixture
into the hot pipe, dropping a liberal quantity upon the carpet during
the process. He raised his eyes to me, and his face was very grim.

"Petrie," he said, striking a match on the heel of his slipper, "the
resources of Dr. Fu-Manchu are by no means exhausted. Before we quit
this room it is up to us to come to a decision upon a certain point." He
got his pipe well alight. "What kind of thing, what unnatural, distorted
creature, laid hands upon my throat to-night? I owe my life, primarily,
to you, old man, but, secondarily, to the fact that I was awakened, just
before the attack--by the creature's coughing--by its vile, high-pitched
coughing..."

I glanced around at the books upon my shelves. Often enough, following
some outrage by the brilliant Chinese doctor whose genius was directed
to the discovery of new and unique death agents, we had obtained a clue
in those works of a scientific nature which bulk largely in the
library of a medical man. There are creatures, there are drugs, which,
ordinarily innocuous, may be so employed as to become inimical to human
life; and in the distorting of nature, in the disturbing of balances and
the diverting of beneficent forces into strange and dangerous channels,
Dr. Fu-Manchu excelled. I had known him to enlarge, by artificial
culture, a minute species of fungus so as to render it a powerful agent
capable of attacking man; his knowledge of venomous insects has probably
never been paralleled in the history of the world; whilst, in the sphere
of pure toxicology, he had, and has, no rival; the Borgias were children
by comparison. But, look where I would, think how I might, no adequate
explanation of this latest outrage seemed possible along normal lines.

"There's the clue," said Nayland Smith, pointing to a little ash-tray
upon the table near by. "Follow it if you can."

But I could not.

"As I have explained," continued my friend, "I was awakened by