“He never ‘smiles’ for any but the chevalier and his son, I believe you said,” he remarked.  “I wonder if the chevalier himself would be as safe if he were to make a feint of doing that?” For the chevalier, like most of the other performers, had not changed his dress after the matinee, since the evening performance was soon to begin; and if, as Cleek had an idea, that the matter of costume and make-up had anything to do with the mystery of the thing, here, surely, was a chance to learn.

“Make a feint of it?  Certainly I will, doctor,” the chevalier replied.  “But why a feint?  Why not the actual thing?”

“No, please—­at least, not until I have seen how the beast is likely to take it.  Just put your head down close to his muzzle, chevalier.  Go slow, please, and keep your head at a safe distance.”

The chevalier obeyed.  Bringing his head down until it was on a level with the animal’s own, he opened the ponderous jaws.  The beast was as passive as before; and, finding no trace of the coming of the mysterious and dreaded “smile,” he laid his face between the double row of gleaming teeth, held it there a moment, and then withdrew it uninjured.  Cleek took his chin between his thumb and forefinger and pinched it hard.  What he had just witnessed would seem to refute the idea of either costume or make-up having any bearing upon the case.

“Did you do that to-day at the matinee performance, chevalier?” he hazarded, after a moment’s thoughtfulness.

“Oh, yes,” he replied.  “It was not my plan to do so, however.  I alter my performance constantly to give variety.  To-day I had arranged for my little son to do the trick; but somehow—­Ah!  I am a foolish man, monsieur; I have odd fancies, odd whims, sometimes odd fears, since—­since that awful night.  Something came over me at the last moment, just as my boy came into the cage to perform the trick I changed my mind.  I would not let him do it.  I thrust him aside and did the trick myself.”

“Oho!” said Cleek.  “Will the boy do it to-night, then, chevalier?”

“Perhaps,” he made reply.  “He is still dressed for it.  Look, here he comes now, monsieur, and my wife, and some of our good friends with him.  Ah, they are so interested, they are anxious to hear what report you make upon Nero’s condition.”

Cleek glanced round.  Several members of the company were advancing towards them from the “living-tent.”  In the lead was the boy, a little fellow of about twelve years of age, fancifully dressed in tights and tunic.  By his side was his stepmother, looking pale and anxious.  But although both Signor Martinelli and the Brazilian coffee planter came to the edge of the tent and looked out, it was observable that they immediately withdrew, and allowed the rest of the party to proceed without them.

“Dearest, I have just heard from Tom that you and the doctor are experimenting with Nero,” said the chevalier’s wife, as she came up with the others and joined him.  “Oh, do be careful, do!  Much as I like the animal, doctor, I shall never feel safe until my husband parts with it or gives up that ghastly ‘trick.’”