Oceanic currents depend on the winds, like the trades in the tropics, and an obstructing bank or shoal adds surf action to the streaming. If corallines and _Tridacna_ clams and crabs add organic cements, a horseshoe hill is built on the sea bottom. Big eddies will do the same kind of work as little eddies. This phenomenon extends all the way from the galaxies of stars with their beautiful spirals, to the spiral eddies in molten lava rushing down a pit crater, or to the streaming of protoplasm in a plant. De Candolle, the great botanist, studied rippledrift in order to try to solve the most abstruse problem in all biology, the unsolved mystery of cell division. At some critical point a budding cell decides to form a partition and divide in two. Why or how? De Candolle thought that the protoplasm granules circulating around the cell walls might start regular lumps on those walls, and so build rippledrifts and make eddies. Thus a current and an eddy and mathematics might start many of the doubles, triples, hexagons, and stars of the world of shells and living tissues. And the cells could pile up in symmetry in the submicroscopic world. The erosion of the earth’s surface reveals symmetries. River maps look like trees with branches and with rivulets as twigs. Other symmetry is in the horizontal plane of the ocean, where headland furnishes pebbles and the sand sweeps into pure curves of beach and bar and cusp. So a delta builds into a lake of leaf shape and annual layers are added as the flood seasons come. Some of the fingerlike drainage of erosion cuts into plowed lands during a rainy spell. This suggests what might be done with a spray, a mud bank, and a tank, to see how the finger valleys form. This erosion of the runoff of water was imitated in the Harvard laboratory. A beautiful river pattern on a slope, like the trickle of raindrops on a windshield, was made by tipping up a rectangular glass plate covered with very liquid clay. A portion clung to the glass, and exquisite fernlike streams formed on the upper half of the plate, with a bank of distributaries of V-shape on the lower slope. This glass plate was used for a surface of stamp mill slimes, of thicker beds, and was eroded with an atomizer and water by means of a barbershop air compressor. The slimes are very fine pounded sands with angular fragments. To get a stream pattern, this is necessary, so as to have fine grit to cut down the rivulets between the coarse grit remnants. This resembles the requirements for ripples.