This invention provides an improved system for monitoring and recording cell cultures. An improved lid (10) for the system includes pin sockets (28) interposed between traces (24) on a printed circuit board (22) and elongated, electrically conductive pins (38). A method for measuring a delay period for an alternating current voltage applied across a pair of pins (38) improves the stability of measurements made with the improved system. A method for applying a voltage across a pair of pins (38) which avoids exceeding a pre-established voltage avoids the possibility of damaging and/or destroying cells while monitoring their culture. Subtracting electrical conductivity measured for a reference well (16) that holds only cell growth media without cells from the electrical conductivity measured for other wells (16) during analysis of recorded data improves the presentation of test results obtained by monitoring and recording cell cultures.