If sections of ground bone are first coated with a plastic solution before applying the usual mounting medium and a cover glass, excellent optical differentiation results. The solution consists of 28 g of Parlodion dissolved in 250 ml of either butyl or amyl acetate. Bone sections are prepared by grinding to the desired thinness, dehydrated with alcohol, air dried, dipped in the solution, freed of surface bubbles by agitation, and placed on a slide. After allowing the preparation to dry thoroughly, the customary mounting medium and cover glass are applied. The plastic seal prevents the escape of air from the lacuni and canaliculi, preserves the natural differentiation of bone tissue, and also permits it to be viewed with a polarizing microscope.