care."

"Yes," said Jones as the professor paused.

"He has disappeared."

"When?"

"Permanently, since ten days ago."

"Permanently?"

"Up to that time he had absented himself without reporting to me for
only three or four days at a time."

"He lived with you?"

"No. He had been aiding me in certain investigations at my
laboratory."

"In what line?"

"Metallurgy."

"When did he stop?"

"About four weeks ago."

"Did he give any reason?"