Mr. Mappin sat up stiffly in his chair. "Do you remember my showing you all at Glencader a needle which had on its point enough poison to kill a man?"

"And leave no trace—yes."

"Do you remember that you all looked at it with interest, and that Mr. Fellowes examined it more attentively than any one else?"

"I remember."

"Well, I was going to kill a collie with it next day."

"A favourite collie grown old, rheumatic—yes, I remember."

"Well, the experiment failed."

"The collie wasn't killed by the poison?"

"No, not by the poison, Mr. Stafford."

"So your theory didn't work except on paper."