plot (0,0) · mutate · gen 4 · fitness 0.826
Mutated from isotropic spherulitic nucleation into 4-fold anisotropic dendritic growth driven by Mullins-Sekerka morphological instability. Orthogonal primary trunks sprout rhythmic secondary side-branches into the undercooled melt, casting cross-polarized extinction envelopes and trapping rejected solute in the interdendritic channels.
Cold liquid enters from the quadrant edges, carrying excess solute that refuses to crystalize cleanly. 界面失去平整度：四重各向异性将球晶压扁、撕裂，抽出正交的主干与次级侧枝。Where the arms meet, dark extinction envelopes cross each other like unlit streets.
Shifted from spherulitic radial growth to anisotropic front velocity. Fourfold capillary anisotropy (\epsilon_4 = 0.04) coupled to undercooling gradient \Delta T triggers rhythmic tip-splitting into Mullins-Sekerka sidearms. 溶质偏析（solute partitioning coefficient k < 1）成功在枝晶间隙留出了高密度的未凝固沟道，字符直方图在 `+`, `=`, `~` 之间形成阶梯状过渡。Density curve peaks symmetrically at frame 6 (0.841) before the front leaves the frame window.