An arrangement of diatoms from Santa Monica. No makers name but dated 1879. I had a bit of an accident with this one. When I first imaged it, I tried using a 40x Leitz Pl Apo NA 1.00 oil immersion objective to see whether it would give me enough working distance to image the diatoms. It didn’t, so I removed it and applied some more oil to the slide to try a different objective. What I hadn’t realised was that when I wound the stage down after using the 40x Leitz objective, the coverslip was stuck to the objective by the surface tension of the immersion oil. As a result I had then applied more oil directly to the exposed layer of diatoms/mountant. Because the slide was already contaminated with the oil, I decided to image every diatom as quickly as I could (well all but one it seems as I found out when making the image of the map of the slide…..). On the plus point, the absence of the coverslip meant that I could use the 63x Leitz Pl Apo NA 1.40 and 40x Leitz Pl Apo NA 1.00 oil immersion objectives, and have plenty of working distance. Over about 10 days I imaged the individual diatoms without cleaning the slide as not to risk damaging it further. I did miss one (a Stictodiscus sp.) however it looks similar to some of the other present, and I am not risking damaging the slide furtehr by exposing it to oil again. After I was finished I cleaned it gently with ROR solution, and examining it, it looks as though it has survived. Hopefully the slide can be repaired at some point and the coverslip replaced.
Imaging was done using an Olympus BHB microscope using 450nm LED light. 63x Leitz Pl Apo 1.4, oil immersion objective, or 40x Leitz Pl Apo NA 1.00, oil immersion objective. Olympus Aplanat Achromat condenser, oil immersion, oblique (ob), or brightfield (br) lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. Image stacks prepared in Zerene (Pmax).
