Growing before your eyes

28th October 1994 at 00:00
Roger Frost discovers the wonders of video microscopy for science. Students are adept at seeing the wrong things down a microscope. They spot air bubbles and black bits. They see their eye lashes before they see the amoeba. If there were laws of biology, like those in physics, the first law would say they'll see everything but the thing they're meant to. It's not their fault, of course, but there is some delightful technology, called a videomicroscope, to help.

This is a small video camera, without the lens, attached to a microscope. The camera plugs into a monitor or television so everyone can see what is happening.

While it is not new and certainly not cheap, the fact that you can show everyone exactly what you want them to look for a red cell or a white cell, a plant cell or a nucleus makes a micro-world of difference. Phil Punyer from City and Islington College will tell you it simply is the business and it has even allowed him to use a video recorder to good effect. "Not only can we show the image on the screen, we can record daphnia, amoeba and budding hydra on video tape. We can count heart beats or show the effect of drugs such as aspirin and then replay the tape or freeze-frame it. We use it for quantitative work too, such as measuring the growth of a yeast population. We use a haemocytometer (a slide with a grid to help you count the number of cells present) and start off with a dilute yeast suspension and count the yeast over an hour. The students then plot the growth rate on a graph."

It's not all for biology either. Microscopically challenged chemists can show crystals of sulphur in all their glory or show the effects of polarised light on crystals.

Or the physicists might use a magnetic domains apparatus to show normally "invisible" magnetic regions forming in a crystal of garnet. With a big screen there's no need for anyone to form a queue round this one.

But the buyer, however moneyed, needs to beware. You need to make sure the monitor can deliver the quality that the camera is capable of, though Phil Punyer is fairly content with his large Sony Trinitron television. But he insists on the best microscopes and uses one of the Swift M3200 series with JVC camera: "Do get a quality microscope with an adjustable light source and a mechanical stage." The stage lets you move deftly around a root tip as you look for dividing cells. Otherwise, at high magnifications, you just can't move the slide slowly enough, especially when you're pointing at the screen at the same time." The basic advice is to get the system demonstrated for you.

Phil Tunstall, from Langdon School, Newham found a significantly cheaper solution, called the Tamron Microvix. This is a one-piece microscope and camera unit which is as plug-and-play as you'd ever dream of. You plug the Microvix into a television set and set a specimen in place.

At Langdon School, there are no clumsy television trolleys either, as the TV set is fixed to the wall with a swivel-bracket. And it all takes pride of place in the science department's very own, state-of-the-art computer room. While the Microvix does suffer from a coarse focusing control, so you often overshoot your mark, it is still good enough for the less-detailed work Phil Tunstall had in mind. "We started using it to show the moving cilia of a paramecium, and we plan to use it to show crystals growing," he says. With so many computers to hand, he has connected the microscope to an Archimedes computer, using a fairly inexpensive video digitiser box. "This allows us to capture images to use on 'computer worksheets'," he explains.

"The children use the computers to label, colour in, and write about the images. And unlike most video recorders, the computer can be set up to 'take a picture' every minute or so and make a film showing, say, the growth of the pollen tube. We could just show them the final video, but when the children do it themselves, they get a better idea of the timescale."

When it's cheque book time, it's time to find a solid seat. You'll need around Pounds 900 for a camera, up to Pounds 950 for a monitor and something with three noughts for a decent microscope. Until prices get real, it's something for a windfall.

The Tamron Microvix costs Pounds 660. As this was going to press, Philip Harris informed us that their suppliers have ceased importing it.

For further details about video microscopes, contact: Philip Harris, Lynn Lane, Shenstone, Lichfield, Staffordshire WS14 0EE. Tel: 0543 480077, fax: 0543 480068 Griffin and George, Bishop Meadow Road, Loughborough, Leicestershire LE11 0RG. Tel: 0509 233344

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