Once the boat ran hard aground on a sand-bar, and for some time it was feared that the whole cargo would need to be removed to lighten the craft sufficiently to get her off. But by pulling hard upon ropes fastened to anchors placed in the rear of the boat, and a vigorous backing of the engines at the same time, they managed to get afloat. One morning, while crawling along through a fog, they crashed into the bank, but happily with no great force; some of the lighter work of the boat was broken, but the hull remained uninjured. When near the Amazon the boat struck hard against something that was supposed to be a log. The engines were stopped, and an examination showed that instead of a log it was a huge turtle, that had evidently been taking a nap on the surface, and was unconscious of the steamer's approach. One afternoon, as they were turning a point under the overhanging branches of an immense tree, the upper works of the boat brushed against a wasps' nest; the disturbed insects came on board without invitation, and for some minutes they made things very lively. Frank was stung on the nose, and that ornament of his face began to swell almost immediately; it was assuming gigantic proportions when the Doctor made an application of ammonia that soon neutralized the effect of the poison, though not until the youth had suffered considerable pain. [Illustration: WASP-NEST, SHOWING INTERIOR CONSTRUCTION.] Manuel explained that the particular kind of wasp which had caused the trouble was known as the "Yessi Marabunta," a large black wasp with a powerful sting. His nest in the limbs of a tree resembles a Dutch cheese, and it is generally inhabited by a large family. There are several varieties of wasp on the Amazon; all of them are troublesome, and some are actually dangerous to life. Away from the rivers they are numerous in the neighborhood of springs, and cause great annoyance to cattle going to drink; in the towns and villages they take possession of the upper part of the houses, building their nests under the eaves and beneath the roof. Woe betide the individual who disturbs them in their occupations, unless he is protected by coverings their lances cannot penetrate. While they were passing under another tree a snake dropped on board, close to where the captain was standing on the upper deck, engaged in giving directions to the man at the wheel. It was a member of the boa family, about six feet in length; though he was classed as "harmless," there was a manifest desire of the captain to get out of the reptile's way, and both Frank and Fred, who were in the vicinity, showed similar inclinations. The intruder was equally frightened, and wriggled towards the edge of the deck, whence a push with a pole sent him spinning overboard.