1. Method of trimming a specimen for sectioning by a microtome comprising the steps of cutting a thin, partly transparent section from said specimen, removing said partly transparent section from said specimen, treating said partly transparent section to provide a contrasting image of a small specimen area of interest, illuminating said partly transparent section and the surface of the specimen from which said section has been cut, providing an optical path, one portion of which extends through said partly transparent section, for simultaneously viewing optically superimposed images of said illuminated partly transparent section and the surface of the specimen from which said section has been cut in a beam combining microscope to identify the location of the small specimen area of interest on the surface of said specimen by reference to the corresponding visible location on said partly transparent section, and further trimming said specimen by reference to said superimposed images.