"Could yeh sell me half a bottle to try it, sir?" she asked.
The vender shook his head. "Impossible, my dear madam. Contrary to my fixed professional rule. But, I'll tell you what I will do. If, in three days you're not better, you can have your money back."
She began painfully to count out her coins. Reaching impatiently for his price, the Professor found himself looking straight into the eyes of the well-dressed stranger.
"Are you going to take that woman's money?"
The question was low-toned but quite clear. An uneasy twitching beset the corners of the professional brow. For just the fraction of a second, the outstretched hand was stayed. Then:—
"That's what I am. And all the others I can get. Can I sell you a bottle?"
Behind the suavity there was the impudence of the man who is a little alarmed, and a little angry because of the alarm.
"Why, yes," said the other coolly. "Some day I might like to know what's in the stuff."
"Hand up your cash then. And here you are—Doctor. It is 'Doctor,' ain't it?"
"You've guessed it," returned the stranger.