A system for crystallization of a protein sample comprising a first mixing cell, a reagent cocktail that is adapted to be added to the first mixing cell, a second mixing cell with the protein sample adapted to be added to the second mixing cell, and a transfer device between the first mixing cell and the second mixing cell. The transfer device comprises structure that allows the reagent cocktail in the first mixing cell to flow into the second mixing cell and mix with the protein sample and allows the protein sample in the second mixing cell to flow into the first mixing cell and mix with the reagent cocktail. The mixture of the reagent cocktail and the protein sample are allowed to incubate to produce protein crystals.
 The United States Government has rights in this invention pursuant to Contract No. W-7405-ENG-48 between the United States Department of Energy and the University of California for the operation of Lawrence Livermore National Laboratory.