a mistake. Two other passengers did the same, a young fellow and a
man of about fifty, with a rough gray beard. Tignol did not see the young
fellow again, but when he got off at the Champs de Mars, the gray-bearded
man got off also and followed across the bridge to the opposite platform,
where both took the train back to Auteuil.

This was suspicious, so at Auteuil Tignol left the station quickly, only to
return a few minutes later and buy another ticket for the Avenue Henri
Martin. There once more he crossed the platform and took a train for the
Champs de Mars, and this time he congratulated himself that no one had
followed him; but when he got off, as before, at the Champs de Mars and
crossed the bridge, he saw the same gray-bearded man crossing behind him.
There was no doubt of it, he was being shadowed.

And now Tignol waited until the train back to Auteuil was about starting,
then he deliberately got into a compartment where the gray-bearded man was
seated alone. And, taking out pencil and paper, he proceeded to write a
note for Coquenil. Their meeting was now impossible, so he must fasten this
explanation, along with his full report, under Caesar's collar and let the
dog be messenger, as had been arranged.

"I am sending this by Caesar," he wrote, "because I am watched. The man
following me is a bad-looking brute with dirty gray beard and no mustache.
He has a nervous trick of half shutting his eyes and jerking up the corners
of his mouth, which shows the worst set of ugly yellow teeth I ever saw.
I'd like to have one of them for a curiosity."

"Would you?" said the man suddenly, as if answering a question.

Tignol stared at him.

"Excuse me," explained the other, "but I read handwriting upside down."

"Oh!"

"You say you would like one of my teeth?"

"Don't trouble," smiled Tignol.

"It's no trouble," declared the stranger. "On the contrary!" and seizing
one of his yellow fangs between thumb and first finger he gave a quick
wrench. "There!" he said with a hideous grin, and he handed Tignol the
tooth.

They were just coming into the Auteuil station as this extraordinary
maneuver was accomplished.

"I'll be damned!" exclaimed Tignol.

[Illustration: "'There!' he said with a hideous grin, and he handed Tignol
the tooth."]

"Is it really as good as that?" asked the stranger, in a tone that made the
old man jump.

Tignol leaned closer, and then in a burst of admiration he cried: "_Nom de
dieu! It's