either from a
man or a woman. At the same instant there was a heavy thud, which shook
the old house, and then all was silence. The maid stood petrified for a
moment, and then, recovering her courage, she ran downstairs. The study
door was shut, and she opened it. Inside young Mr. Willoughby Smith was
stretched upon the floor. At first she could see no injury, but as she
tried to raise him she saw that blood was pouring from the underside of
his neck. It was pierced by a very small but very deep wound, which had
divided the carotid artery. The instrument with which the injury had
been inflicted lay upon the carpet beside him. It was one of those small
sealing-wax knives to be found on old-fashioned writing-tables, with
an ivory handle and a stiff blade. It was part of the fittings of the
Professor's own desk.

"At first the maid thought that young Smith was already dead, but on
pouring some water from the carafe over his forehead he opened his eyes
for an instant. 'The Professor,' he murmured--'it was she.' The maid is
prepared to swear that those were the exact words. He tried desperately
to say something else, and he held his right hand up in the air. Then he
fell back dead.

"In the meantime the housekeeper had also arrived upon the scene, but
she was just too late to catch the young man's dying words. Leaving
Susan with the body, she hurried to the Professor's room. He was sitting
up in bed horribly agitated, for he had heard enough to convince him
that something terrible had occurred. Mrs. Marker is prepared to swear
that the Professor was still in his night-clothes, and, indeed, it was
impossible for him to dress without the help of Mortimer, whose orders
were to come at twelve o'clock. The Professor declares that he heard the
distant cry, but that he knows nothing more. He can give no explanation
of the young man's last words, 'The Professor--it was she,' but imagines
that they were the outcome of delirium. He believes that Willoughby
Smith had not an enemy in the world, and can give no reason for the
crime. His first action was to send Mortimer the gardener for the local
police. A little later the chief constable sent for me. Nothing was
moved before I got there, and strict orders were given that no one
should walk upon the paths leading to the house. It was a splendid
chance of putting your theories into practice, Mr. Sherlock Holmes.
There was really nothing wanting."

"Except Mr. Sherlock Holmes," said my c