Mr. Upton confessed incompetence unashamed.

“I never heard of these cigarettes before; they’re an imported article; you can’t get them everywhere, I’ll swear! Your boy has got to rely on them; he’s out of reach of the doctor who’s forbidden them; he’ll try to get them somewhere! If he’s been trying in London, I’ll find out where before I’m twenty-four hours older!”

“But how can you?” asked Mr. Upton, less impressed with the possibility than by this rapid if obvious piece of reasoning.

“A. V. M.!” replied Eugene Thrush, with cryptic smile.

“Who on earth is he?”

“Nobody; it’s the principle on which I work.”

“A. V. M.?”

“Otherwise the old nursery game of Animal, Vegetable, or Mineral.”

Again Mr. Upton had to prevent himself by main force from declaring it all no laughing matter; but his silence was almost bellicose.

“You divide things into two,” explained Thrush, “and go on so dividing them until you come down to the indivisible unit which is the answer to the riddle. Animal or Vegetable? Vegetable or Mineral? Northern or Southern Hemisphere? Ah! I thought your childhood was not so very much longer ago than mine.”