From the opposite bank two trails branched off up the mountainside. The one that was most difficult to follow, Dr. Rander chose.
“From here our going will be more arduous,” he told the young men. “The mountains are steeper, and more obstacles will stand in our way.”
Bob had followed the pack train to a height where he could command a good view of the surrounding country when suddenly he cried out in pain.
“My foot!” he groaned, when the others rushed to his side. “Something bit it.”
“What was it? A snake?” Joe demanded anxiously.
“Let me have a look at it,” the old man said, tying the foremost mule to a gnarled tree.
When Bob removed his legging and sock, he found a large red scratch, and the flesh about it was already badly swollen. It pained severely and throbbed so violently that the boy could hardly hold his foot still.
“Not a snake,” Dr. Rander told him. “Rather a poisonous insect—they are common in the Andes.”
The old explorer bathed the foot in water from a canteen and treated it with antiseptics, wrapping it up firmly.