A flexible container containing pre-deposited reagents, comprising a plurality of temporarily sealed, breakable compartments dispersed in the container, each compartment containing a reagent useful for immuno-assaying, and each compartment comprising opposed confining walls at least one of which is sufficiently flexible as to allow the compartment to be compressed in the presence of an adequate external force, external outlets in the container for the contents of said compartments, passageways extending from each of the compartments to the outlets, each of the outlets terminating in a platform that supports a drop of at least 10 .mu.L as a pendant drop, the platforms of at least two of the outlets being adjacent so as to form between them an exterior angle with respect to each other sufficient to cause drops pendant therefrom to substantially uniformly intermix.