 Since Dpp is present in a gradient, it is conceivable that the slope of the gradient could be the measurement by which a tissue determines how large it is.If the amount of Dpp at the source is fixed and the amount at the edge of the tissue is zero, then the steepness of the gradient will decrease as the size of the tissue and the distance between the source and the edge increase.Experiments where an artificially steep gradient of Dpp is induced in wing tissue resulted in significantly increased amounts of cell proliferation, lending support to the steepness hypothesis.