An arrangement of four Nitzschia rabenhorstii from Amherst, Burma (now Kyaikkhami, Myanmar). Prepared by WA Firth. Published in: Grunow, A. (1880). On some new species of Nitzschia. Journal of the Royal Microscopical Society, ser. 3 3: 394-397, pls 12, 13. This name is currently regarded as a synonym of Tryblionella rabenhorstii (Grunow) D.G.Mann. Olympus BHB microscope using 450nm LED light. Main image shows a crop of the two central diatoms, rotated 90 degrees. 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. 34 images stacked in Zerene (Pmax).
The slide gives a couple of measurements. Trans striae 45,000 per inch (564nm spacing) and Long ? (I am assuming puncta spacing for this) 64,000 per inch (397nm). I did two measurements of each of these in ImageJ, one per diatom, to get an idea for these. Striae spacing was measured as 539nm and 547nm, so a little shorter than Firth (about 3% difference). Puncta spacing was measured as 396nm and 410nm, so very close to Firth’s measures. Given the obvious variability seen by looking at the images, with other replicates I may get closer to Firth’s numbers.