expected to behave.

"A curious business," I continued. "I am a doctor, and therefore very
much interested in it."

His manner changed. He assumed the attitude of the average man towards a
doctor at once, and I was gratified to observe it.

"I was just thinking I'd like to hear what a doctor thinks about it," he
said, laying down his paper. "I thought of calling in on Dr. Sykes on my
way home to-night; he attends my wife. Do you know Dr. Sykes?"

"Which one?" I asked cautiously, not willing to disappoint him.

"Dr. Sykes of Harlesden," he said, with a look of surprise.

"Oh, yes, I know Dr. Sykes. Why did you think of going to see him?"

He smiled apologetically and pointed to the paper.

"It sounds so queer ... the disease. They say, up in Birmingham, that
it's stopping all diseases in the hospitals ... everywhere. People
getting well all of a sudden. Now I don't believe that."

"Have you seen a case yet?"

"Yes. A woman. In the street this afternoon as I was coming from lunch.
The police took her. She was mad, I can tell you. There was a big crowd.
She screamed. I think she was drunk." He paused, and glanced at me.
"What do you think of it?"

I took a deep breath.

"I don't _think_, I _know_," I said, in as quiet a manner as possible.
He stared a moment, and a nervous smile appeared and swiftly vanished.
He seemed uncertain what to do.

"You've found out something?" he asked at length, playing with his
teaspoon and keeping his eyes on the table. I regarded him carefully. I
was not quite certain if he still thought I was a doctor.

"I'm not a lunatic," I said. "I'm merely stating a rather extraordinary
fact. I know all about the germ of the Blue Disease."

He raised his eyes for an instant, and then lowered them. His hand had
stopped trifling with the teaspoon.

"Yes," he said, "the doctors think it's due to a germ of some sort." He
made a sort of effort and continued. "It is funny, some of these germs
being invisible through microscopes. Measles and chickenpox and common
things like that. They've never seen the germs that cause them, that's
what the papers say. It seems odd--having something you can't see." He
turned his head, and looked for his hat that hung on a peg behind him.

"One moment," I said. I took out my card-case. "I want you to read this
card. Don't think I'm mad. I want to talk to you for a particular reason
which I'll explain in a moment." He took the card hesitatingly and read
it.