Microslides

Abstract

2.9.1 Microslides Microslides are relatively easy to store and may be kept at room temperature under normal conditions. Slides should be handled gently, kept in the dark and at cool temperatures, and stored on stable shelving, especially in the case of large and heavy slide collections (Carter and Walker 1999). Permanent mounts are best prepared with resin-based products, such as Canada balsam and Euparal for botanical and mycological specimens, (Carter and Walker 1999) and epoxy resins for fossils. As slide mounts will always remain fluid to some extent, they should be stored flat with the mount on the upper side. Slotted slide boxes, for instance, should be stored upright like books on a shelf and marked in a way that indicates how to open the box correctly, to prevent slides from falling out and breaking. Microslides may be stored together with the main collection or separately with other microslides. Fossil microslides In fossils, the size of the microslide should correspond to the nature of the fossil, whether it be a longitudinal or tangential cut or a cross section, a small or large fossil, or a cross-drilling sample from a large fossil (e.g. Chinsamy and Raath 1992, Stein and Sander 2009). Commonly used microscope slides for fossils, also referred to as palaeohistological slides, come in different sizes: common formats are 2.5 × 5 cm, 5 × 5 cm, 7.5 x 5 cm. Unusual formats may include anything up to self-cut window panes measuring tens of centimetres in length and width. Palaeohistological slides are usually thicker than standard microscopy slides used in biology labs. They can be up to several millimetres thick, partly to withstand strains on the slide that might occur during the preparation of the fossilised samples. Due to the wide range of sizes and thicknesses, palaeohistological slides are stored in a variety of different slide boxes. Labels for microslides Care must be taken with slide labels. Some commercially available slide labels are unsuitable for permanent preparations because of the poor quality of the paper or glue. If a self-adhesive label is used, ensure that it is of archival quality (with acid-free adhesives) (Carter and Walker 1999). Recommendations à standardise storage types if possible à use resin-based mounting for long-term storage, i.e. Canada balsam and Euparal in botanical and mycological preparations, and epoxy resins infossil preparations Examples to see one of the largest collections of palaeohistological slides in Switzerland, visit the PIM in Zürich to see preserved microscopic algae (diatoms) on microslides and stored in histologic preparation boxes, see the MHNG in Geneva for taxonomic studies, the type specimens represented in the cryptogamic collection of the CJBG in Geneva have been removed from the general collection and stored in separate fire-proof metal cabinets (Clerc et al. 2017) Supplier storage boxes can be bought from a broad range of histology lab suppliers like Carl Roth Laborbedarf (Arlesheim CH, www.carlroth.com/ch) Further reading for an extensive overview of storing, managing, and digitizing slide collections see Neuhaus et al. (2017)