BOOK REVIEW by Bob Goldsack, Wahroonga, NSW, Australia.
Ernie Ives (2009),
A Guide to Wood Microtomy: Making quality microslides of wood
sections, 2nd edition (CD).
Available from Savona Books, 400 Seawall Lane, Haven Sands, North Cotes, Lincolnshire, DN36 5XE, UK.
Before presenting my review of A Guide to Wood Microtomy, I must declare an interest. Firstly, I made a few minor suggestions for the first edition, and, secondly, I own a large number of wood sections prepared by the author.
With the exception of Averellís paper (1926), OíBrien and McCully (1981) remarked that wood anatomists of yesteryear had published precious little detail about the methods they had used for preparing wood for microscopic examination. In 1998, Jansen et al. published a very useful review on this topic. Unfortunately, this appeared in a specialist journal not readily available to hobby microscopists. With the appearance of A Guide to Wood Microtomy, this serious deficiency has now been rectified. To the best of my knowledge, this is the only English language book devoted to this subject. Although you can teach yourself a lot of botany with a supply of interesting plant material, plenty of sharp razor blades and a microscope (Cutler (1978), Cutler et al. (2008)), things get a lot more difficult when it comes to sectioning wood, particularly the hard ones that grow in my garden and the nearby bush.
This edition has been produced as a CD, and although it is not convenient to read in bed, an advantage is that itís possible to print the parts required for bench reference. If you drop stain or your favourite tipple all over it, you will only have ruined a few sheets of paper instead of an entire book.
Although I havenít done a word count, this edition seems a little longer, possibly because the text is arranged full page instead of in two columns. The book is very well illustrated with colour photographs and clear diagrams, some of which are new. Thankfully, all dimensions are metric and the civilized world is spared from having to convert from imperial in to metric units. The book is divided into 8 chapters viz.: Becoming a Wood Microscopist, Microtomes and Microscopes, Sharpening Microtome Knives, Preparation of Wood blocks, Wax Embedding, Cutting Sections, Staining and Clearing, and Mounting.
Chapter 2 covers microtomes and microscopes. Microtomes ranging from the simple hand held ones to the much more refined sledge and sliding models are discussed. I was taken with the Swiss designed portable sliding microtome made by GSL. Freehand sections can be cut from some woods using razor blades and details are given on how to sharpen razor blades using a simple homemade jig. Using a commercially available jig, I can confirm that it is worthwhile sharpening single edged razor blades; the result is a cutting edge that is much sharper than that straight from the packet. It is also makes good economic sense to resharpen blades if their edges are not nicked. In 1957, Shellkorn and Hoshaw showed that it was possible to cut thin sections of wood with a sharp carpenterís plane. However, they did not give much detail on technique. Ernie shows how a good quality, well-tuned block plane can be used as a poor manís sliding microtome. I surprised myself by getting an acceptable transverse section from a piece of very dense (1240 kg per cubic metre) Xanthostemon melanoxylon (Myrtaceae) from the Solomon Islands using my Lie-Nielsen block plane. I simply moistened the surface with a little water, and planed away! Microscopes are not covered in great depth. This is not a draw back because a wealth of information exists in Micscape Magazinesís archives and readily available books such as those published by the Royal Microscopical Society.
Although the sharpening of plane irons and razor blades is explained in chapter 2, some 14 pages in chapter 3 are devoted to sharpening microtome knives. Clear instructions are given for making knife backs so that knives can be ground and honed at the correct angles. This will of great value to people like me whoíve acquired several microtome knives without their backs. Not only does the author tell us what sharpening methods work, he also tells us what did not work for him. This will save the beginner from wasting time and effort and help prevent a lot of frustration. I did find a couple of errors in mathematical notation on page 27 viz.: 0.63 (tan17.5 x 2) should read 0.63 (2tan17.5); and 0.556 (tan15 x 2) should read 0.556 (2tan15).
Chapter 4 covers the preparation of wood blocks prior to sectioning. First of all, the blocks must be cut so that the tangential longitudinal (TLS) and radial longitudinal surfaces (RLS) are at 90 degrees to each other, with the transverse surface (TS) being at 90 degrees to both the TLS and RLS. Ernie clearly describes his technique for doing this. More often than not, I find this job a bit fiddly but it is important to do it properly. If you donít, you will be wasting your time going any further. Although the author uses a gentís saw, I would like to give Japanese saws a plug. These make a fine kerf on the pull stroke and are sharp enough to tackle Australian nail-bending timbers like mulga (Acacia aneura), Cooktown ironwood (Erythrophleum chlorostachys) and lemon-scented gum (Corymbia citriodora). Ernie stresses the value of keeping good records of experimental procedures. I was trained as a chemist where laboratory notebooks are routinely used. These days, Iíve found one is an absolute necessity because my short-term memory is getting bad as I slide in to my dotage. The importance of measuring wood density before trying to cut sections is emphasised. Generally, as wood density increases so does its physical hardness. An indication of hardness is very useful for helping you to select a suitable softening method before sectioning. Moreover, density is a (very useful) quantitative property that can be very useful in wood identification.
I share Ernieís enthusiasm for using a 4 percent (v/v) aqueous solution of 1,2-ethylenediamine (EDA) also called (1,2-diaminoethane) for wood softening. Some workers reuse the softening solution but I discard it because it turns dark-brown to black. This is caused by acidic materials in the wood reacting with the alkaline EDA to form coloured water-soluble salts. If you cannot get hold of EDA, steam can also be used to soften wood. I have to take issue with the steam generator shown in Fig. 4.17. In the interests of safety, there should be a straight glass tube passing through the bung in the flask neck to well below the water surface. This acts as a safety valve; if the steam line becomes blocked for any reason, a pressure build up could occur and burst the flask. The coil shown in Figs 4.17 and 4.18 is definitely not a condenser; its purpose is to dry the steam. I would be happier if a tripod gauze were placed between the flask and flame (Fig. 4.16). The gauze helps to prevent flasks cracking through localised overheating. The use of a spirit burner over a Bunsen burner running off the town gas supply has a lot going for it. It you forget you are boiling while you go off to the pub, the burner runs out of fuel. In regard to using hydrofluoric acid (HF), I wholeheartedly agree with the author in not using it to soften wood. Its use seems to be for dissolving silica in woods such as turpentine (Syncarpia glomulifera). HF is notorious for causing very unpleasant skin burns that are slow to heal and it should be avoided like the plague.
If a mechanical vacuum pump is used to aid infiltration of the softening agent, a trap needs be placed between the pump and the EDA container. This will prevent any froth from getting into the vacuum pump. I know from bitter experience, that it is not much fun pulling a vacuum pump apart to clean it. It is also important to disconnect the pump before turning the power off. If the pump doesnít have an anti-suck back mechanism, pump oil will find its way in to the EDA container. For his EDA infiltration container, Ernie has wisely used a Buchner flask that is designed to work under reduced pressure. If you decide to make your own infiltration container from a jar, make sure it is thick walled and that you wrap it well with electrical insulation tape or some thing similar. If an implosion occurs, this will reduce the chances of glass shards flying around the kitchen.
Some physically soft woods need to be hardened before sectioning and Chapter 5 goes in to the techniques of achieving this, including handling very small samples and making moulds. Those made from paper will appeal to origami enthusiasts.
My wife, who, in a previous life, was a mammalian histologist, has given me the strong impression that section cutting can be something of a black art! As far as I am concerned this is the really hard part of making wood sections. The methods used by the author are thoroughly covered. Any problems and their resolution are well covered and there is a very useful trouble shooting list at the end of the chapter.
Staining and clearing methods are discussed in chapter 7. If you canít afford to buy the special containers for these processes, Ernie describes several of pieces of apparatus that you can make from odds and ends. Although cotton wool and polyester fibre plugs will remove larger particles from stains, it is preferable to invest in some good quality laboratory filter papers, as these will remove those fine particles that only show up when you come to admire your handiwork with the microscope.
The fine art of mounting wood sections is presented in chapter 8. I must endeavour to put the authorís advice into practice, as I always seem to get my sections ending up jaunty angles or with a bubble or two, or both. The important topic of finishing off a preparation so that it looks neat is well covered. After creating your masterpiece, be sure to label it clearly. Ernie suggests making your own labels with a computer so as to get a neat job. Today, very few of us can prepare the labels written in copperplate by the Victorians. Several ways of storing slides are mentioned but as Ernie is a craftsman, he has made his slide storage cabinet.
A useful bibliography and a list of organizations devoted to wood and microscopy are included. Right at the end, the authorís has modestly hidden his biography.
I found a few minor spelling errors in the text and couldnít get the index to print out. The latter was not a problem because I have always been able to find what I wanted simply by flicking over the pages of the relevant chapter.
As mentioned earlier, I have a large number of slides made by the author and I can say that that his techniques produce high quality slides. A surprising amount of information is contained in this book. I was very impressed with the authorís DIY approach to making equipment that is not readily available or expensive. The wealth of information offered will be of immense value to microscopists who like to prepare their own sections, even those not particularly interested in wood. I also believe this book contains a lot information that will be useful to researchers, particularly those on minuscule budgets and who lack the funds for buying latest Ďgizmosí for wood microscopy. Ernie Ives is to be congratulated for making the effort to write down his experiences in preparing wood for microscopic examination.
When I visited London earlier this year, I quickly found that the cost of this CD (GBP 10) would not buy very much! I sincerely believe that this CD represents outstanding value for your money. So, if you like to make your own microscope slides buy a copy. You wonít regret it.
All comments to the author Bob Goldsack are welcomed.
J.L. Averrell (1926), Suggestions to beginners for cutting and mounting wood sections for microscopic examination, Journal of Forestry, 24, 791-781.
D.F. Cutler (1978), Applied Plant Anatomy, Longman, London and New York.
D.F. Cutler, C.E.J. Botha and D.M. Stevenson (2008), Plant Anatomy an Applied Approach, Blackwell Publishing, Oxford.
S. Jansen, P. Kitin, H. De Pauw, M. Idris, H. Beeckman and E. Smets (1998), Preparation of Wood Specimens for Transmitted Light Microscopy and Scanning Electron Microscopy, Belgian Journal of Botany, 131,, 44-49.
T.P. OíBrien and M.E. McCully (1981), Study of Plant Structure: Principles and Selected Methods, Termarcarphi Press Pty Ltd, Melbourne.
S.L. Shellkorn and R.W. Hoshaw (1957), Rapid method for preparing wood sections, Stain Technology, 32, 156-160.
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