A multiple tube holder is suspended at the upper end on a frame so that the lower end can pivot through a small arc about a horizontal axis adjacent the upper end of the holder. A motor is connected to the lower end of the holder for pivoting the lower end of the holder through said small arc at a rate of approximately 1800 cycles per minute. A tray means is positioned below the holder for supporting a cooling liquid at a controlled temperature so that the lower end of the tubes on the holder will be immersed in the liquid to prevent destruction of proteins and enzymes released during cell breakage.