1. A method for identifying neural stem cells or neural progenitor cells comprising: (a) suspending neural cells in a semi-solid medium which supports the growth of neural cells; (b) plating the cells in the semi-solid medium at a cell density that allows for the production of colonies; (c) culturing the plated cells until size differences can be discerned between the colonies; and (d) estimating colony size wherein the larger colonies are likely produced by neural stem cells and wherein the smaller colonies are likely produced by neural progenitor cells.