Sometimes the Indians of the interior take skins, etc., to the Paraguayan towns across the river. Not knowing the use of money, their little trading is done by barter. Their knowledge of value is so crude that on one occasion they refused a two-dollar axe for an article, but gladly accepted a ten-cent knife. The Chaco Indian, however, is seldom seen in civilization. His home is in the interior of an unknown country, which he wanders over in wild freedom. While the Caingwas are homekeeping, these savages are nomadic, and could not settle down. The land is either burnt up or inundated, so they do not plant, but live only by the chase. So bold and daring are they that a man, armed only with a lance, will attack a savage jaguar; or, diving under an alligator, he will stab it with a sharpened bone. The same man will run in abject terror if he thinks he hears _spirits_. Though not religious, the savages are exceedingly superstitious, afraid of ghosts and evil spirits, and the fear of these spectral visitants pursues them through life. During a storm they vigorously shake their blankets and mutter incantations to keep away supernatural visitors. All diseases are caused by evil spirits, or the moon; and a comet brings the measles. The help of the witch doctor has to be sought on all occasions, for his special work is to drive away the evil spirit that has taken possession of a sick one. This he does by rattling a hollow calabash containing stones. That important person will perform his mystic _hocus pocus_ over the sick or dying, and charm away the spirits from a neighborhood. I have known an Indian, when in great pain through having eaten too much, send for the old fakir, who, after examination of the patient and great show of learning, declared that the suffering one _had two tigers in his stomach_. A very common remedy is the somewhat scientific operation of bleeding a patient, but the manner is certainly uncommon--the witch doctor sucks out the blood. One I was acquainted with, among the Lengua tribe, professed to suck three cats out of a man's stomach. His professional name was thereafter "Father of Kittens." The doctor's position is not one to be envied, however, for if three consecutive patients die, he must follow them _down the dark trail!_ These medicine-men are experts in poisons, and their enemies have a way of dying suddenly. It cannot be denied that the Indians have a very real knowledge of the healing virtues of many plants. The writer has marvelled at the cures he has seen, and was not slow to add some of their methods to his medical knowledge. Not a few who have been healed, since the writer's return to civilization, owe their new life to the knowledge there learned.