Abstract: An apparatus includes a conveyor system for conveying tubes, having respective self-sealing closure members, sequentially to a station whereupon the conveyor system is temporarily halted. At the station, a clamping device having a clamp lowers to prevent movement of the tube. An arm moves in the direction of the tube to enable a hollow needle to penetrate the closure member of the tube. A metering pump enables a predetermined volume of a fluid, preferably liquid agar, to be introduced into the tube. Following release of the needle from the closure member, the conveyor systems moves to enable another tube to arrive at the station.