Abstract: A device for simultaneously performing multiple biochemical or immunological reactions. A manifold plate rests atop a waste fluid collection chamber or receptacle suitable for attachment to a vacuum pump. The manifold contains a series of wells that serve as reaction vessels. The sides of each well are fluid-impermeable, and its lower end provides a planar, annular base. A hydrophobic membrane is sealed to the lower surface of the base of each well. The membrane is formed of a material through which fluid can be drawn upon application of vacuum while retaining the fluid within the well in the absence of vacuum. By placement of a solid-phase support for binding biological coreactants atop the membrane prior to initiation of the reaction, solid-phase reaction products can be collected when vacuum is applied and can then be freely withdrawn from its well.