The interface motion during the growth process of Pb5Ge3O11 from the melt is visualized in an in situ observation system. The formation of the striation aggregation is observed, and the rates of the interface motion Rim are measured. It turns out that there are sharp changes in the growth rate during the formation of the striation aggregation. It has been found that the typical fluctuation in the rates can be associated with the kinetics and transport mixed control during the crystal growth. The non-uniform composition normal to the interface gives rise to the striation aggregation. Of particular importance in the investigation are the typical interfacial melt flows from the corners to the center of the interface observed in the experiments. The relation between the rates of this interfacial melt flow R-if and the time t is also provided showing that the change of supersaturation adjacent to the interface gives rise to the interfacial melt flow. (c) 2005 Elsevier B.V. All rights reserved.