"I knew that all along," he said, with irritating politeness.

"What is it you want with me? Will you detain me long?"

"Not very long; it will depend upon yourself. I come on behalf of Dr. Peterssen."

My anger instantly subsided; I became as cool as my visitor.

"Enter," I said, "and let us get it over. Who is Dr. Peterssen, and what has he got to do with me, or I with him?"

These last words were spoken when my visitor and I were standing face to face in my sitting-room.

"Oh, I am not here to answer questions," said my visitor. "I have a commission to execute, and a question or two myself to ask on behalf of Dr. Peterssen."

"Which I shall answer or not, as I please."

"Of course it is entirely within your discretion; I cannot force you; I am merely an instrument."

"I must know with whom I am conversing," I said, "before we proceed further."