A slide labelled as Cymbella helvetica from un-named reservoir (1939). Material from H Gleave, collected in 1939. Mounted in Aroclor and dated April 1975. Prepared by Bernard Hartley. Olympus BHB microscope using 450nm LED light. I chose an example Cymbella helvetica for high magnification imaging. 63x Leitz Pl Apo 1.4 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 9 images stacked in Zerene (Pmax).
Cymbella helvetica. Cymbella helvetica Kützing 1844. Published in: Kützing, F.T. (1844). Die Kieselschaligen Bacillarien oder Diatomeen. pp. [i-vii], [1]-152, pls 1-30. Nordhausen: zu finden bei W. Köhne. Page 79, Plate 6, Figure 13.
Slide 654 from Bernard Hartley’s Sample and Strew Slide Collection PDF (accessed from here).