A multilevel, disposable cartridge may have a plurality of fluid wells or reservoirs holding a plurality of reagents, and a sample viewing area to view a biological sample. The reagents may be applied sequentially to the sample by opening a specific valve formed in an elastomeric, flexible layer under the fluid well. The fluid channels may be formed in a first rigid plastic layer to conduct the reagent to the sample. Pneumatic channels for applying suction or pressure to the valves may be formed in a second rigid, plastic layer.