"Who made that trail?" inquired Will, much interested.
"It was cut by the Spanish conquerors of Peru nearly four hundred years ago," returned the scientist. "They used to send expeditions down into the Amazon region after slaves to work their mines. Since then," he went on, "it has been kept open by the Indians themselves, and, as far as I know, has not been traversed by a white man for centuries. I learned the secret of it many years ago, while I was living with one of the wilder tribes," he finished.
The professor's plan was adopted unanimously, Jud not voting.
Then followed nearly a week of wonderful hunting and collecting. Even Jud, who regarded everything with a severe and jaundiced eye, could not conceal his interest in the multitude of wonderful new sights, sounds, and scents which they experienced every day. As for Will, he lived in the delightful excitement which only a bird-student knows who finds himself surrounded by a host of unknown and beautiful birds. Some of them, unlike good children, were heard but not seen. Once, as they pushed their way in single file along a little path which wound through the jungle, there suddenly sounded, from the dark depths beyond, a shriek of agony and despair. In a moment it was taken up by another voice and another and another, until there were at least twenty screamers performing in chorus.
"It's only the ypicaha rail," remarked the professor, indifferently.
Hen Pine, who was in the rear with Will, shook his head doubtfully.
"Dis ol' jungle," he whispered, "is full o' squallers. De professor he call 'em birds, but dey sound more like ha'nts to me."
Beyond the rail colony they heard at intervals a hollow, mysterious cry.
"That," explained Pinto, "is the Witch of the Woods. No one ever sees her unless she is answered. Then she comes and drives mad the one who called her."
"Nice cheery place, this!" broke in Jud.