Guess What's In This Jar |
At times all of us get a bit lazy or careless or are in a hurry or simply procrastinate. Actually, now we can even say "I'll do that next millennium" and really mean it. So, what am I fussing about this time? Slides, bottles, jars, vials, small plastic boxes, large plastic boxes, round tins, square tins, paper envelopes, plastic bags , and glassine envelopes—containing what? "Aye, there's the rub!" That's the question. There aren't any labels or there are a few numbers and letters constituting some cryptic codes with no list in sight to help you decipher.
Recently I acquired a number of samples of micro-fossils. Many of these samples date back to 1972, some to 1935 and a few to 1907. Some are well labelled and the labels contain a significant amount of information. The other extreme is, of course, no label at all. And then, there are those labels that read: VX-20 73-24, 2 of 4. I'm sure that at one time that meant something to someone, but it certainly isn't any help to me now; it might as well not have a label. This problem is frustrating enough when dealing with material that someone else has collected, but it's downright embarrassing when the material is part of your own collection and you find yourself asking yourself: "I wonder what this is?"
I like enigmas and puzzles and mysteries, but there have to be a few clues. A jar of greenish glop labelled "1979, Planet Earth," simply isn't enough to go on. Under the microscope, you might discover that this green muck actually consists of a mass of Spirogyra which you preserved. And then you ask yourself—why did I want a pint of preserved Spirogyra? Perhaps when you were collecting, you had had too many pints of something else that day. After racking your brain and not coming up with a satisfactory answer, you decide that it must have been something other than the Spirogyra itself, something associated with the Spirogyra. Let's face it, Spirogyra doesn't preserve very well. It's best to bring it into the lab, process it and make some slides. So you decide to look for whatever else it is that's supposed to be in the jar and you take bottom samples with a pipet and examine them carefully under the microscope and you look along the filaments of the Spirogyra. Finally, after an hour, you admit that you don't have the slightest idea of what's supposed to be in the jar other than pickled Spirogyra and so you toss the whole mess into the garbage.
More frequently I will find a jar or vial that does have a label telling me what's in it; for example:
Burgundy Cyclops
July 18, 1987
Hourglass Lake
North Shore
Snowy Range Mountains
Above Centennial, Wyoming
The organisms in question are quite wonderful. They are about 3/4 of an inch in length and are indeed possessed of a rich burgundy color when alive. However, on examining the 14 year old remains of these once elegant creatures, I wonder why on earth I tried to preserve them—they are shrivelled, distorted, and bleached of color; in short, a pathetic simulacrum of what they once were.
If one wishes to preserve hard structures, such as, the shells of ostracods or small mollusks or the spines, spicules, plates and pedicellariae of echinoderms, then that's quite sensible provided one takes proper precautions. For example, with ostracods, it's essential to observe them alive first and to make careful, detailed notes regarding patterns and coloration on the shells. In most preservatives, the color tends to bleach out after a period of time and there is a great deal of color variation in ostracods which can, in some instances, be helpful in classifying them. Your specimen vial and your notes should both have the same code number, so that you can find the relevant information when needed.
The other thing that is crucial is to maintain the preserving fluid at a neutral pH. If it becomes acidic, it will gradually erode and dissolve the very structures you are trying to preserve and study. This is especially a problem with formalin solutions. One can get special buffering solutions to achieve a neutral or very slightly alkaline pH, but the simplest method is to get some marble chips. In each container with formalin, and especially with your stock solutions, a small chip of marble lying at the bottom will maintain the proper pH and also help avoid the formation of paraformaldehyde, an insoluble white precipitate which can ruin specimens. Where do I get marble chips, you ask querulously. Support your local sculptor! If you don't happen to know artists who work in marble (Carrara is, of course, the best), then check with the Art department of a school or college or with a biological or geological supply house.
The evaporation of preserving fluids is also an important issue. At one university, I volunteered to help try to restore their reference collection of invertebrates. In numerous instances, the jars had not been properly sealed and much or all of the preservative had evaporated. Many of the specimens were salvageable but unfortunately some were not. With specimens preserved in formalin, be sure to add that marble chip, otherwise, if the jar has a metal lid, the formalin will gradually "eat" the metal producing a mess in the specimen jar. With small specimens in vials, a layer of glycerine can help protect the specimens in case the preservative evaporates.
When one first starts collecting, there is often the temptation to preserve almost everything. Specimens to be preserved should be selected carefully and always with a purpose in mind. For example, you may wish to make an intensive survey of the flora and fauna of a particular location at a local pond and keep preserved specimens of as many types as possible. It is precisely at this point that one may be tempted to sweep one's net through the water a number of times, collect a rich concentration of specimens and then add some aquatic vegetation and some preservative, while promising yourself that you will examine and sort the material promptly, well—soon, well—maybe next millennium.
It is by far the best to set yourself a schedule for processing, sorting, properly preserving, and labelling material which you wish to keep. At least once a year, go through your collection and check to make sure that all is as it should be and, if it isn't, correct whatever is necessary. If you have material that has deteriorated and is no longer useable, discard it. If you find material that is in good condition, but you have an excess of it or are no longer going to make use of it, then give it or trade it to another amateur. Over the years, I have found microscopists and other amateur naturalists to be fascinating and generous people who are almost always pleased to share their particular enthusiasms. This in itself is a good reason for labelling everything carefully, because you can hardly go up to a fellow enthusiast and say: "Hey, would you like to trade something for this jar of green glop labelled "1979, Planet Earth."
A Word of Caution About Preservatives
Formaldehyde is a dangerous chemical—it is a cancer-causing agent, highly poisonous, and very irritating to the skin and membranes. It should always be used in the weakest solution possible to achieve the desired result. For a wide variety of specimens, alcohol is to be preferred. Ethyl alcohol requires a permit and methyl (wood) alcohol is very poisonous. The best compromise is isopropyl alcohol which is relatively inexpensive and can be purchased at a local pharmacy—70% is usually adequate for most specimens. Avoid excessive inhalation of the vapors and avoid skin contact. Remember also that alcohols are flammable and even a spark can ignite vapors. Whenever you use chemicals take extra care. It is always better to be overly cautious when working with potentially dangerous substances.
Comments to the author Richard
Howey welcomed.
Editor's notes:
The author's other articles on-line can be found by typing in
'Howey' in the search engine of the Article Library, link below.
Published in the September 1999 edition of Micscape Magazine.
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