Venetian Turpentine as an Aid in Squashing and Concomitant Production of Durable Chromosome Mounts

Abstract

Root tips are hydrolyzed in 1 N HCl at 60 C for 10–12 min, Feulgen stained, and macerated in a minimal amount of propiono-carmine. A drop of Venetian turpentine mounting medium (Harleco brand was used) is mixed with the carmine stain, the cover slip applied, the tissue pressed gently while observed under a dissecting microscope to spread the chromosomes, and finally firmly squashed. High quality slides of over 1 yr durability are obtained which are well suited to morphological studies, photographing under oil, or routine screening in polyploidy studies. The carmine stain in conjunction with the Feulgen aids to give contrast to chromosomes which are difficult to stain (e.g. hops) but it may be omitted for other species.