An important part of the food supply of these people is furnished by date and olive trees which they grow in the gulches of their limestone plateau. They built a dry rock dam behind which earth-wash lodges. In this the trees are planted and every rain sends more earth and soaks that which has collected. The plan can certainly not be called an experiment for the people have lived there for centuries. They have olive trees that are several centuries old and I have never seen such fine olive trees, not in California, or the plains of Spain, Portugal, France, Italy, or in Algeria or Tunis, and I have seen a good many olive trees in those countries. The olive tree is usually open, light and feathery. These in the Matmatas gulches are thick and black and rank. For automatic cultivation and fertilization the plan of these primitive agriculturists is hard to beat. You put up your stone dam, and every time the gulley runs with water your crop is irrigated and fertilized. Can you beat it? Three Americans of my acquaintance have independently experimented and discovered along similar lines. The late Freeman Thorpe of Hubert, Minnesota, did it with much enthusiasm. So did the late Dr. Meyer, a friend of J. F. Jones, near Lancaster. He discovered it accidentally. He put a brush dam across a gully. Water stood behind it for days after every rain. The apple tree near it grew much more than the others. That started the Doctor. He began to dig small field reservoirs and collect water near trees and he found that it paid even with the very expensive process of hoe and shovel. The idea has been modernized and brought to the machine stage which characterizes our present-day agriculture, by Mr. Lawrence Lee, a civil engineer-farmer of Leesburg, Va. Mr. Lee runs a level line across the face of the clay hills, and then with a Martin ditcher scoops out a terrace on this horizontal line. It makes the terrace so that the water will hold and will not run away. Mr. Lee is sure that nine-tenths of the heavy thunder shower runs off of the hills, in normal conditions of non-plowing, and that if he plows, most of the water and much of the soil go off together. He is also sure that the water pockets hold both water and soil. Rows of apple trees planted below these waterholding terraces thrive without cultivation as well as do other trees across the row with cultivation, but with this difference, ordinary cultivation impoverishes the soil and this enriches it by keeping all mineral and organic matter in the field.