“You knew it was here,” said Scanlon.
“Yes. I came upon it after a little search one day while prowling about in the guise of a man with a disobedient liver.” He regarded the drumhead in silence for a while, and then went on:
“The Aztecs’ places of worship were shaped like pyramids, and were composed of terraces, one above the other. Here their terrible war god, Huitzilopochtli, was propitiated by human sacrifice. A great drum was beaten, notifying all in the city that an offering was to be made. The pinioned victim was thrown face upward across the sacrificial stone, which was green in colour and with a humped up place which fitted into the small of his back; with a blow of a great keen blade his body was laid open.”
The breath caught in the big man’s throat.
“No!” said he, his wide open eyes upon the other’s face. “No!”
He continued to stare, and, slowly, what he had just heard began to form in his mind.
“The stone,” said he, “green, and with a hump on it! The roaring of a great drum! A cut down the front!” His hand closed upon Ashton-Kirk’s arm. “I’ve seen and heard things like these, and I know a man with a flattened skull. But what’s the answer?”
“The greater part of the Mexican population is mixed with Indian blood,” said the crime specialist. “And one of the most curious studies I know of is the atavistic tendency—that is, the tendency to recur to an ancestral type or deformity. A thing may lie dormant in ten generations of men or animals, and then suddenly assert itself in all its fullness.”
“You think, then——” began Scanlon.
“That the man in the rolling chair, Alva, is a ‘throwback’; that his deformed head is an assertation of the old Aztec strain; that if this deformity had anything to do with the fiendish character of the Aztecs, it might naturally be supposed that it has had some effect upon him.”