Abstract: Disclosed is a Petri dish support device comprising two opposed portions, and a space defined between said opposed portions capable of receiving a sheet of material having marked thereon a matrix, the support being adapted to secure a Petri dish above the marked matrix, the matrix being visible through the base of the Petri dish.

Abstract: A liquid dispenser has a cylinder in which a piston may move in an intake stroke and a discharge stroke. A pulse generator responds to any movement of the piston in the discharge direction, whereby a counting and readout device provides a dispensing measurement readout even for inadvertent discharge movements of the piston. Movement of the piston in the discharge direction rotates a wheel in the pulse generator. A ratchet system may be provided to prevent rotation of the wheel in reverse during intake movements of the piston. Alternatively the wheel rotates in both directions, and a discriminator is provided to discriminate between the two directions of movement.

Abstract: A liquid dispenser has a cylinder in which a piston may move in an intake stroke and a discharge stroke. A pulse generator responds to any movement of the piston in the discharge direction, whereby a counting and readout device provides a dispensing measurement readout even for inadvertent discharge movements of the piston. Movement of the piston in the discharge direction rotates a wheel in the pulse generator. A ratchet system may be provided to prevent rotation of the wheel in reverse during intake movements of the piston. Alternatively the wheel rotates in both directions, and a discriminator is provided to discriminate between the two directions of movement.