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Hi, I'm all new to microscopy and the forum so I'm looking for bits of knowledge. I'm a high school grad and got a compound microscope as a gift (model Celestron 44320 digital kit or sumthing like that). I used to use microscope in high school's biology so I made a slide of pond water. The microscope has no dispenser and I don't like using stains because it's hard. Is there anyway I can view bacteria using darkfield illumination?
Thank you so much! any advice is appreciated :]

Congrats with the microscope. I think the world would be a great place if all gifts were restricted solely to microscopes and telescopes!

Dark field is great for bringing out the colours in larger objects, but comes at the price of decreased contrast. Since bacteria are really quite small, and at the limit of the resolving power of most light microscopes, you probably stand a better chance of seeing them using transmitted light (i.e. light shining "through" the specimen from below.)

However, bacteria is only part of the wildlife you should be able to find in that drop of pond water. There may be much larger animals and algae present that can be studied in far greater detail. Critters like rotifers, copepods, ostracods, amoeba, flagellated algae and water bears are all things you can look forward to discovering. Have you seen any of these yet?

Here is a link to one of many useful sites to help you identify your finds.

Micrographia: A Light Microscopy Resource: Home Page and Site Directory.


Mintaka

I haven't been able to see of those microscopic creatures yet. I used transmitted light (bottom illuminator) but somehow I cannot quite discover any of those creatures you mentioned. should I use a low power or high power objective? (40-80, 150-300, or 300-600)? thanks for the reply!

Hi Robwadeson,

I tried looking up your microscope on Celestron's web site if the instrument I found is the same as yours then I don’t think you will see much of bacteria but should see larger organisms as Mintak has said.
I'm not sure what you mean when you say your microscope has no dispenser, do you mean substage condenser? With out a condenser you can not really have darkfield illumination and adding a condenser to your microscope is probably going to be harder than staining bacteria.
As for staining bacteria this may be as simple as adding a touch of food colouring to the drop of pond water on the slide before placing on the cover slip. Experiment and see.

Peter.

Thanks, yes I meant the substage condenser, but somehow I cannot manage to use the microscope to see these larger organisms.

It may be useful experimenting a bit with your microscope's different settings on stationary objects. Microfauna are about the same order of magnitude as fine table salt. Put a few grains on a slide and make adjustmets to your luminescence and magnificatioon and note where you get the best resolution.

Also bear in mind that most organisms in freshwater ponds will not be free swimming but rather adhere to the bottom and water plants. You must sample in these regions.

Hi robwadeson,
Mintaka is right, if you collect clear pond water that is probably all you have (water ). When gathering samples look for algae on submerged rocks or a layer of bubbles on a muddy bottom; lift moss growing over swampy ground and squeeze water into your specimen jar (this is a good source of testacida ). Your water specimens should normally have some sediment from the bottom or scraped from stones living or dead vegetation etc. When you get home you will probably examine your samples immediately, which is all good, however viewing usually improves over the next days to weeks as various populations of flora and fauna expand and feed off each other.
Other things to view from home include the thin membrane between the fleshy layers of an onion (try staining this with food colouring ), pollen (this can be made to "germinate" if mounted in a dilute solution of honey), moth wing scales (if you see a moth at rest, carefully touch its back with a slide as it escapes there will be a dusting of scales left on the slide.
You should always start viewing with the lowest power objective first, scan the slide systematically and change to a higher power to examine objects of interest.

Keep looking and experimenting. Keep asking questions. Good luck.

Peter.

thank you very much i've found many exciting things in this rusty water sample i collected.

Robwadeson

Hi robwadeson,

Can you identify them and tell us what they are?

Peter.