If you get just a little bit of gunky pooling (liquified brown rice flour) in the bottom of your jars during the sterilization process as I do, and get a tad impatient with the subsequent slow growth of the mycelia when they finally get to work in that area, here's how to counteract it. Turn the jar upside down and tap it to make the cake slide down about 1/8 inch. Leave it in this upside down position the last few days until its "birthday." The resulting "headroom" or airspace at the top works wonders in allowing the mycelia to vigorously cover the last of the substrate. Also, I guess, it takes the pressure of fighting the glass (on the bottom of the jar) off of the poor little filamentous fungi (or should I say rhizomorphic mycelia?).