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There are certain South American species which go at least one step farther. They have their own fields--spaces three or four feet in diameter--which are entirely occupied by one single grass, the so-called Ant-rice (_Aristida stricta_). Dr. Lincecum states that the ants "work" these plantations very carefully, removing every weed or other plant that comes up, and sowing every year the new seed at the proper season.[129]