is removed the slots are closed by the co acting rubber profiles because the electrophoresis container rests on the dividing walls 16 and 17 an adequate liquid sealing is realized between on one side the electrophoresis container 18 and on the other the other compartments 10 12 the compartments 10 and 11 are mutually connected via a circuit 23 provided with a pump 22 so that the composition of the electrophoresis liquid 14 is substantially the same in both compartments temperature differences are moreover avoided as far as possible the electrodes not shown are connected to a control unit so that the electrophoresis can be performed in both dimensions semi automatically or automatically after the electrophoresis units 6 have been placed in the apparatus 1 activation of pump 22 is carried out by the same control unit fig3 shows an electrophoresis apparatus 2 according to the invention having substantially the same construction as the apparatus 1 of fig1 compartments 10 and 11 and the middle compartment 12 are mutually separated by the dividing walls 16 and 17 and compartment 13 is again formed by an electrophoresis container 18 as shown all compartments are provided with an electrode 24 27 which is connected via an electrical connection 28 to the control unit not shown the circuit 23 also comprises as shown a communicating conduit 29 the electrophoresis unit 30 which is arranged in an apparatus 2 comprises two standing sides which extend into the respective compartments 10 11 the bottom lying side 34 is situated in the compartment 12 and the upper lying side is situated in the container like compartment 13 the electrophoresis unit 30 comprises two electrically insulating elements 35 and 36 which lie between both glass plates 7 and 8 the electrical element 35 interrupts the electrophoretic contact.