Abstract: Methods for treating biological samples on microscope slides are set forth. One aspect of the invention is the use of predried reagents in wells on trays onto which the slides are placed, especially the use of predried reagents which dissolve sequentially. Yet another aspect of the invention is the use of external controls placed directly on a microscope slide in conjunction with a biological sample to be assayed. The external controls can be conveniently placed on a membrane which can be affixed to the slide. A further aspect of the invention is a specially designed tray to allow whole chromosome painting of all chromosomes of a cell sample on a single slide. The invention is also drawn to a coverslip with concave wells which act as reaction chambers when placed against a slide and filled with buffer. Preferably a reagent is predried in the well.

Abstract: Microscope slides which are useful for manually or automatically processing biological samples are described. External controls may be placed directly on the microscope slide in conjunction with a biological sample to be assayed. The external controls can also be conveniently placed on a membrane which can be affixed to the slide.