MOLLER PROBE-PLATTE: A Test Slide with 23 Diatoms(22 different).

SIGNED:Diatomaceen, Probe-Platte, Monobrom, Napthalin on the left side and I.D.Möller on the right side.

This slide is labeled as a Probe-Platte which translates to sample plate, contains 23 diatoms with the first and last being the same species. Unusually, the diatoms are mostly arranged end to end on this slide. It came to me in a Watson & Sons slide case. Monobromonapthalein is a relatively high refractive index mountant. With a reported refractive index of about 1.66 it has a higher refractive index than Canada balsam, Styrax and Permount, but not as high as Nephrax or Hyrax. This means that in theory, the diatoms will be more easily resolved than with a lower RI mountant. Unfortunately, this slide has some very fine cracks in the coverglass, which although not interfering much with visualizing the individual diatoms with dry objectives, precludes the use of immersion oil with this slide. I have imaged the entire group using dark ground illumination; the rest of the images were taken using DIC illumination with an Olympus 40X S-Plan objective. The red-bordered closeups are enlargments from the same image at the same magnification.