4. Gelatinous or particulated precipitate.
The drop contains gelatinous protein precipitate, sometimes hard to see because it can be transparent.
Check the drop with dark-field illumination: the structural elements appear bright on a dark background.
This is a good starting point (when no crystals are found). Optimize the condition by varying the pH, add a substrate or inhibitor or additive.
With high PEG concentrations (viscose) the protein precipitated when mixing the drop. The drop will contain regions of heavy precipitate and regions that are clear.
Lower the precipitant concentration.