“Not pleasant, but effective,” came the quiet reply; “the exhalations of freshly spilled blood.”

“Not human blood!” cried Colonel Wragge, starting up from his chair with a voice like an explosion. I thought his eyes would start from their sockets.

The face of Dr. Silence relaxed in spite of himself, and his spontaneous little laugh brought a welcome though momentary relief.

“The days of human sacrifice, I hope, will never come again,” he explained. “Animal blood will answer the purpose, and we can make the experiment as pleasant as possible. Only, the blood must be freshly spilled and strong with the vital emanations that attract this peculiar class of elemental creature. Perhaps⁠—perhaps if some pig on the estate is ready for the market⁠—”