As on the day before, he saw, through the ivy, two policemen walking between one lamp-post and the next.  They did not see him.  Moreover, anything that might happen inside the house appeared to be to them a matter of total indifference.

“That’s my great mistake,” said Perenna to himself.  “It doesn’t do to entrust a job to people who do not suspect its importance.”

His investigations led to the discovery of some traces of footsteps on the gravel, traces not sufficiently plain to enable him to distinguish the shape of the shoes that had left them, yet distinct enough to confirm his supposition.  The scoundrels had been that way.

Suddenly he gave a movement of delight.  Against the border of the path, among the leaves of a little clump of rhododendrons, he saw something red, the shape of which at once struck him.  He stooped.  It was an apple, the fourth apple, the one whose absence from the fruit dish he had noticed.

“Excellent!” he said.  “Hippolyte Fauville did not eat it.  One of them must have carried it away—­a fit of appetite, a sudden hunger—­and it must have rolled from his hand without his having time to look for it and pick it up.”

He took up the fruit and examined it.

“What!” he exclaimed, with a start.  “Can it be possible?”

He stood dumfounded, a prey to real excitement, refusing to admit the inadmissible thing which nevertheless presented itself to his eyes with the direct evidence of actuality.  Some one had bitten into the apple; into the apple which was too sour to eat.  And the teeth had left their mark!

“Is it possible?” repeated Don Luis.  “Is it possible that one of them can have been guilty of such an imprudence!  The apple must have fallen without his knowing ... or he must have been unable to find it in the dark.”

He could not get over his surprise.  He cast about for plausible explanations.  But the fact was there before him.  Two rows of teeth, cutting through the thin red peel, had left their regular, semicircular bite clearly in the pulp of the fruit.  They were clearly marked on the top, while the lower row had melted into a single curved line.

“The teeth of the tiger!” murmured Perenna, who could not remove his eyes from that double imprint.  “The teeth of the tiger!  The teeth that had already left their mark on Inspector Verot’s piece of chocolate!  What a coincidence!  It can hardly be fortuitous.  Must we not take it as certain that the same person bit into this apple and into that cake of chocolate which Inspector Verot brought to the police office as an incontestable piece of evidence?”

He hesitated a second.  Should he keep this evidence for himself, for the personal inquiry which he meant to conduct?  Or should he surrender it to the investigations of the police?  But the touch of the object filled him with such repugnance, with such a sense of physical discomfort, that he flung away the apple and sent it rolling under the leaves of the shrubs.