The holiday season will soon be upon us. Perhaps you have a long weekend planned in another part of the country with some walks to study the local wildlife. The bags are packed ... but have you remembered your microscope? No, not the research stand you can hardly lift, but why not take a portable microscope with a few collecting items that can all be fitted in a small box which you may find room for in the car boot or suitcase?
I never considered packing a microscope myself until my last vacation, despite the fact I did have a portable microscope gathering dust. But as an experiment I packed a few items shown in the picture below with the intention of doing a little microscopy while away.
A portable kit for studying pond samples away from home
1) portable microscope
2) selection of containers
a - 35mm film cassette
b - sealable specimen tubes
c - polyethylene bottles for initial pond sample
3) freshwater plankton fixative
4) selection of items for handling specimens
e.g.. paintbrush, mounted needle, forceps, small Petri dish, teat pipette
5) 10X hand lens
I found that a little collecting and evening microscopy back at the accommodation easily fitted in with the rest of the itinerary of a normal holiday. I intentionally left most identification guides at home so I just enjoyed looking at the micro-organisms alive, without feeling the immediate need to identify them. (Preserved plankton specimens were taken for later ID).
So here are a few thoughts on microscopy away from home, based on the author's experiences.
You don't need to spend a lot on a portable microscope. The optics and mechanics are obviously built to a price on the cheaper models, but I think they open up a new aspect to an enjoyable hobby. The microscope shown above and described in more detail below is often available second-hand in the UK. It is based on the compact McArthur style microscope and was specially designed for the UK Open University course for students studying from home. This model has two objectives (80X and 200X) chosen by a tab (not seen). It can be hand-held but is also threaded with a camera tripod thread, so I use it on a table-top tripod available for cameras.
It does require a certain knack to use because the slide is placed upside down, but it can still be used for fluid mounts.
There are a variety of compact or portable microscopes available, including models for casual use or those designed for more serious use. Swift, for example, manufacture a professional field microscope with a variety of accessories. The true McArthur microscope on which the Open University model is based is also a superb piece of design and engineering and intended for professional use. It is sometimes found on the second-hand market, but I believe no longer manufactured. The Swift and McArthur models are described and illustrated in the article by Don Bruce and Bill Ells, My Favourite Microscope. The Nikon Model H field microscope is now a highly sought after classic, and described in this Micscape article by Bill Amos.
There is also a portable microscope available with a novel design called the Lensman with magnifications of 80X and 200X. Click here for a review of this microscope by Mike Dingley.
An alternative to buying a dedicated compact / field microscope, is to purchase a basic compound microscope sold to schools or students ensuring the eyepiece and objectives are to the recognised standards. Such stands are small and lightweight enough for portability. Chuck Huck in Topical Tips 6 describes some approaches to do this. This allows you to select objectives and eyepieces from your possibly more sophisticated home 'stand' to take with you. If you were interested in studying subjects where a stereo microscope would be more suitable than a compound microscope, there are a variety of lightweight stereo microscopes available.
Detail of Open University (UK) students microscope based on the McArthur design
(The standard 3x1 inch slide shown indicates scale.)
1) fixed eyepiece
2) selector for external or internal battery lighting
3) light port (for daylight viewing)
4) slide holder (slide sits upside down)
objectives are below slide in case
5) slits for filters e.g. polarisers
6) focusing knob
The items you take to collect and sort the samples do of course depend on the microscopic subjects of interest e.g. pond organisms, mosses, insects etc. The author's particular interest is micro- and macro-invertebrates in freshwater especially the Cladocera (water fleas). While out on a walk on holiday I don't carry all the items above, just a few sample bottles and a compact home-made plankton net (shown left with a 35mm film cassette for scale) which easily fits in a small rucksack.
After collecting a plankton sample, I keep half the sample alive for examining back at the accommodation, with a second sample preserved on the spot in a bottle containing a small amount of fixative. Larger invertebrates such as beetles and dragonfly larva collected in the plankton sample are returned to the pond after examining on the spot with a 10X hand lens.
For safety I don't carry the bottle of fixative (formaldehyde based), but just put a few mls of fixative before setting out in the well sealed tubes, which is topped up with the pond water containing the specimen.
Sorting and examining specimens
The items illustrated above are used to isolate those organisms of interest. Only a few simple items like pipette, forceps, small Petri dish are needed for sorting the catch. The plankton of interest is isolated and transferred with a little water to a standard microscope slide which has an aluminium spacer ring glued at the centre. This is covered with a cover slip and examined under the portable microscope. Microscope suppliers often sell these rings in three thickness' to support the cover slip while examining plankton.
Back at the accommodation when on holiday I enjoy examining live pond organisms just for pleasure using these temporary fluid mounts, taking notes where necessary, and the preserved specimens can be more fully identified if desired when returning home.
So, I hope I've encouraged you to carry on your microscopy while away from your permanent set-up. It needn't be expensive and can add a whole new dimension to your holiday and hobby. If you have your own favourite methods and equipment for microscopy away from home, we would be pleased to hear from you.
A final thought: Don't forget that there are regulations for carrying chemicals on public transport, as well as very necessary controls about taking live specimens across national boundaries. Not to mention rules about sampling plant or animals from nature reserves private land etc. Please make yourself aware of local regulations if planning to collect specimens away from home.
Comments to the author Dave Walker welcomed.
Home-made plankton net In case of interest a home-made net can be easily made. The one illustrated above used an aluminium coat hanger for the wire, a small hose clip, a bamboo stick and glass pill-bottle. The netting was cut from a bag from the local chemist sold to filter the fines from home-made beer or wine. The mesh size of the netting was 100-200 microns. This is fine enough to collect invertebrates such as the water fleas of interest to the author. It is not suitable for collecting smaller organisms such as rotifers where mesh as fine as 60 microns may be needed. The silk fabric used for silk screen printing is often this fine, so a local printer may be able to provide off-cuts. Return to article.
Microscopes and supplies A number of UK microscopy dealers catering for the naturalist and hobbyist sell a variety of microscopes suitable for portable use. Some of these dealers are also able to supply plankton/algal fixatives, various collecting equipment and sample handling kit.
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