"Earthquake?" The elder Englishman spoke as though afraid of disturbing
some one.

The French doctor shook his head.

"No," he answered in the same tone. "Look."

The rats, in all their weaving confusion, displayed one common impulse.
They sprang upward continually, with short, agonized leaps, like
drowning creatures struggling to keep afloat above some invisible flood.
The action, repeated multitudinously into the obscure background,
exaggerated in the foreground by magnified shadows tossing and falling
on the white walls, suggested the influence of some evil stratum, some
vapor subtle and diabolic, crawling poisonously along the ground.

Heywood stamped angrily, without effect. Wutzler stood abject, a
magician impotent against his swarm of familiars. Gradually the rats,
silent and leaping, passed away into the darkness, as though they heard
the summons of a Pied Piper.

"It doesn't attack Europeans." Heywood still used that curious
inflection.

"Then my brother Julien is still alive," retorted Doctor Chantel,
bitterly.

"What do you think, Gilly?" persisted Heywood.

His compatriot nodded in a meaningless way.