Indians, although they lived on the product of the ground, were obliged to continue the chase because of the materials and implements which they got from the animals. They used the jaw of a fish, with the teeth in it, as a knife; the arm and leg bones of apes as arrow points; the tail spike of a skate for the same; the two front claws of the armadillo to dig the ground (a process which the animal taught them by the same use of his claws); the shell of a river mussel as a scraper to finish wooden tools. "These people were hunters without dogs, fishers without hooks, and tillers without plow or spade. They show how much development life was capable of in the time before metals."[170] The palometa is a fish which weighs two or three pounds. It has fourteen teeth in each jaw so sharp that the Abipones shear sheep with the jaw.[171] Such cases might be pursued into great detail. They show acute observation, great ingenuity, clever adaptation, and teachableness. The lasso, bola, boomerang, and throw knife, as well as the throw stick, are products of persistent and open-minded experience. The selection and adaptation of things in nature to a special operation in the arts often show ingenuity as great as that manifested in any of our devices.[172] This ingenuity is of the same kind as that shown by many animals. Intelligent experiment, however, is not wanting. It is reported of Eskimo that they invent imaginary hard cases, such as might occur to them, and, by way of sport, discuss the proper way to deal with the case.[173] Operations similar to this in play show a mode in which ingenuity must have been developed and inventions produced. In the higher grades of the hunting stage, such as are presented by the North American Indians, buffalo hunting, for instance, calls for the highest organization and skill, and establishes inflexible discipline.[174]