not shown the merely schematically shown electrode holder 40 serves the purpose of a permanently fixed positioning of the measurement electrodes 41 42 relative to the perfusion device 10 the electrode holder 40 comprises for example a frame known as such possibly with a 3d precision setting device as an alternative the measurement electrodes 41 42 are attached to manipulators which are standing on holders which are mechanically joined to the chamber body 20 the measurement electrodes 41 42 are pushed through the input openings 22 23 into the sample chamber the perfusion device 10 is provided with at least one of the following reference electrodes a first reference electrode 43 is arranged in the discharge 24 it can be advantageous for ion current measurements if two reference electrodes are used for this purpose a second reference electrode 44 ought to be in the immediate vicinity of the cell at which the measurements are carried out in this way influences of interference resistances e g series resistances on the measurement are minimized in an advantageous embodiment one of the reference electrodes 44 is integrated in the holding device 30 the electrode protruding from the holder in the immediate vicinity of the cell in this way the reference potential can be formed immediately beside the cell as an integral component of the holding device the electrode 44 can be detached by.