An arrangement of three Navicula lyra. One looks to have moved from its original location (I presume these where originally in a row next to each other). Prepared by Watson and Sons Ltd. Mounted in Hyrax and dated 17th May 1933. The mount has a lot of debris / crystallization in it as can be seen in the image before I cleaned it up. Interestingly Watson mention in their catalogues from around this time that Hyrax slides could be made to order, but that their permanency could not be guaranteed. I am presuming this was early days for the use of Hyrax so its behavior over time was less well understood.
Olympus BHB microscope using 450nm LED light. 40x Leitz Pl Apo NA 1.00 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, brightfield lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 20 images stacked in Zerene (Pmax).