Abstract: The apparatus of the invention is in the form of a kit comprising two distinct elements designed to be assembled together and to co-operate during immunological analysis. The first element is an incubation element that includes at least one receptacle suitable for receiving a mixture comprising a substance to be analyzed and a test substance. The second element is a reaction element and includes at least one well which is closed by a sealing membrane and which has a bottom on which a reactionally sensitive layer is fixed. The apparatus includes means for assembling said elements together and perforation and injection means, e.g. a tapering tube, projecting from the bottom of the receptacle of the incubation element and extending outwards, said means being suitable firstly for perforating the membrane and then for injecting the contents of the receptacle into the well through said perforated membrane, once the two elements have been assembled together.