An arrangement of Asteromphalus hookeri (plus another diatom). Quite low contrast, so probably Canada Balsam. Initials say W.G. I have a few slides by this maker (such as here), and it could be W Gardner, although I will leave it with a question mark for now. Olympus BHB microscope using 450nm LED light. As well as the wider field I imaged two using the 63x Leitz Pl Apo 1.4 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, oblique lighting. 2.5x Nikon CF PL photoeyepiece. 11mm removed from the tube to the camera to increase the field of view. Monochrome converted Nikon d850 camera. 65 images stacked in Zerene (Pmax).
Asteromphalus hookeri Ehrenberg, 1844. Published in: Ehrenberg, C.G. (1844). Einige vorläufige Resultate seiner Untersuchungen der ihm von der Südpolreise des Captain Ross, so wie von den Herren Schayer und Darwin zugekommenen Materialien über das Verhalten des kleinsten Lebens in den Oceanen und den grössten bisher zugänglichen Tiefen des Weltmeeres. Bericht über die zur Bekanntmachung Geeigneten Verhandlungen Der Königl. Preuss. Akademie Der Wissenschaften zu Berlin 1844: 182-207. Page 200.
Also see: Hallegraeff, G.M., Leblanc, K. New observations on the Antarctic Asteromphalus darwinii/hookeri diatom species-complex (Asterolampraceae). Polar Biol 46, 759–772 (2023). https://doi.org/10.1007/s00300-023-03160-6