It has been a few days since I acquired a tray of 20 odd clones, of which only 4 had roots emerging from the rockwool cubes. Having bunged them in a propagator on 31/08/07 (3 days ago) a 9th clone has displayed roots emerging from its' cube. I busted open a 10th cube to see what's happening and took a pic to let it explain itself.

The first few pics are of the clones that have had roots showing for longer than 2 days, while the last pic is of a clone that I expect to be showing within the next 2 days.