I found the paper: "Enumerating phytoplankton with an upright compound microscope using a modified settling chamber" by P.B. Hamilton and I'm currently trying to replicate the new chamber myself, but wondered if anyone else has tried this? Thanks for any info you can give!
http://link.springer.com/article/10.1023%2FA%3A1017523301767#page-1
NB: had written a first reply which unfortunately was deleted due to not
Hi Jeanette, there really is no good way around an inverted microscope.
The Hamilton method with an upright microscope would work just about with a routine 40x objective. The suggestion that this Hamilton slide could be used with a high power oil immersion is ridiculous (unless you put it upside down on an inverted microscope, so that all organisms sink on the surface of the coverslip). Besides, it still is a matter of sample concentration: if it is not dense enough, you will have to search the whole slide for only a couple of cells.
Good luck, René
Thank you both for your help and information Wolfgang and Rene!
I have given up trying to make my own chamber (was not working properly), and have gone back to the Utermohl settling chambers with an inverted microscope. I was initially hoping to use increased magnification for some better species ID, but did not think about some of the lower density samples and the time it would take to search for cells!
Cheers,
Jeanette
just a short note on resolution for identification
- you are probably aware that composed chambers, where the settling cylinder is removed after sedimentation, allow a better resolution than chambers with permanently mounted cylinders? (in addition, avoid using any resin or vaseline for tighten the chamber, as this also impairs your resolution)
- you can easily collect material for inspection on an upright microscope by settling a sample settle in a centrifuge tube, then collect the material by a pipette from bottom and transfer on a slide.
- often the iodine will impair your vision of cellular structures. You can remove it by adding thiosulfate to the sample. Works also on sedimented samples (but do it after sedimentation, as the iodine helps in the process of sedimentation)
Robert
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