Abstract: In a method for drawing at least one fraction of solid substance by suction from a heterogeneous stock of several solid substances, which are segregated according to granular size and/or specific weight by supplying a segregation fluid, for example water, into a segregation zone at a distance from a suction nozzle of a suction pipe held in the stock, a selected fraction of segregated solid substances together with the fluid being conducted away in the form of a suspension through the suction nozzle water is vigorously injected into a ground layer for washing out the soil so that a fraction of fine grains is picked up in a whirl and can thus be directly sucked off through the suction pipe. With this method it cannot be avoided that both fine and coarse grains are sucked up together by one and the same suction nozzle.