Mitchington showed a desire to speak, and Bryce paused.

“What about what Ransford said before the Coroner?” asked Mitchington.  “He demanded certain information about the post-mortem, you know, which, he said, ought to have shown that there was nothing poisonous in those pills.”

“Pooh!” exclaimed Bryce contemptuously.  “Mere bluff!  Of such a pill as that I’ve described there’d be no trace but the sugar coating—­and the poison.  I tell you, I haven’t the least doubt that that was how the poison was administered.  It was easy.  And—­who is there that would know how easily it could be administered but—­a medical man?”

Mitchington and Jettison exchanged glances.  Then Jettison leaned nearer to Bryce.

“So your theory is that Ransford got rid of both Braden and Collishaw—­murdered both of them, in fact?” he suggested.  “Do I understand that’s what it really comes to—­in plain words?”

“Not quite,” replied Bryce.  “I don’t say that Ransford meant to kill Braden—­my notion is that they met, had an altercation, probably a struggle, and that Braden lost his life in it.  But as regards Collishaw—­”

“Don’t forget!” interrupted Mitchington.  “Varner swore that he saw Braden flung through that doorway!  Flung out!  He saw a hand.”

“For everything that Varner could prove to the contrary,” answered Bryce, “the hand might have been stretched out to pull Braden back.  No—­I think there may have been accident in that affair.  But, as regards Collishaw—­murder, without doubt—­deliberate!”

He lighted another cigarette, with the air of a man who had spoken his mind, and Mitchington, realizing that he had said all he had to say, got up from his seat.

“Well—­it’s all very interesting and very clever, doctor,” he said, glancing at Jettison.  “And we shall keep it all in mind.  Of course, you’ve talked all this over with Harker?  I should like to know what he has to say.  Now that you’ve told us who he is, I suppose we can talk to him?”

“You’ll have to wait a few days, then,” said Bryce.  “He’s gone to town—­by the last train tonight—­on this business.  I’ve sent him.  I had some information today about Ransford’s whereabouts during the time of disappearance, and I’ve commissioned Harker to examine into it.  When I hear what he’s found out, I’ll let you know.”

“You’re taking some trouble,” remarked Mitchington.

“I’ve told you the reason,” answered Bryce.

Mitchington hesitated a little; then, with a motion of his head towards the door, beckoned Jettison to follow him.

“All right,” he said.  “There’s plenty for us to see into, I’m thinking!”

Bryce laughed and pointed to a shelf of books near the fireplace.

“Do you know what Napoleon Bonaparte once gave as sound advice to police?” he asked.  “No!  Then I’ll tell you.  ’The art of the police,’ he said, ’is not to see that which it is useless for it to see.’  Good counsel, Mitchington!”