Methods for the detection and/or quantification of a biological material in a sample. The method includes the steps of liquefying the sample (if necessary) and pouring the liquefied sample into the incubation vessel. The incubation vessel has a generally flat horizontal surface and the surface is divided into at least one incubation site. Each incubation site is adapted to hold an aliquot of liquid and is sized and shaped, and formed of a suitable material, to hold the aliquot within the well by surface tension. Any excess liquid from the liquefied sample is poured from the surface of the incubation vessel. The method then involves incubating that incubation vessel until the presence or absence of the biological material is determined. The presence of air bubbles can be dramatically reduced by the presence of a surface acting agent in the liquid sample deposited on the device surface. Such an agent can be added to the sterile diluent used to prepare the test reagent, can be separately added to the test reagent after it is prepared, or can be added to the test sample directly while it is being prepared for testing.