|
|
 |
|
The micro-world Looking at the night sky through a really good telescope for the first time was a memorable experience for me: it was amazing to see the rings on Saturn for real, but even more exciting was looking into what, through binoculars, was a clear space between stars and finding it glittering with thousands upon thousands of tiny pinpoints of light. The immense size of the universe strikes home, making us feel very insignificant here on our tiny planet suspended in such vast and star-strewn space. I had a similarly mind-expanding experience last week, looking not up but down, in fact, peering through a microscope. The Wharfedale Naturalists Society holds monthly meetings for members interested in microscopy, when we can enjoy exploring anything from minerals to fungi, butterfly wings, to owl pellets. This time I was examining a drop from a flask of liquid which our leader had squelched out of a sphagnum peat bog. It looked like a dribble of slightly dingy water, but the powerful microscope revealed a whole world - with its own dramas and cast of characters, a world which challenged my preconceptions of the distinctions between plants and animals and between animate and inanimate. First, a green object, rather like a neat courgette, made its way steadily across my slide. It was obviously swimming, so clearly an animal. Not a bit of it. My cucumber friend was a diatom, a kind of algae called Pinnularia, and its movement was effected by rhythmically circulating part of the contents of its one cell in and out of its body - in one end, out the other, back along two grooves on its sides and in again. It had evolved this strategy so that it could adjust its position and remain in the optimum layer of water in order to obtain light for photosynthesis, the process by which plants use sunlight to make more complex molecules from carbon dioxide and water. It was a plant, and not swimming at all. The water was full of other diatoms - the commonest neatly rectangular. In fact many of the shapes I observed were geometric. Among the rectangular shapes were a number of orange hemispheres. Imagine half a ripe melon, cut-side uppermost. These were not moving as far as I could tell - but they were, in fact, a kind of amoeba, a uni-cellular animal. In one, the remains of a rectangular diatom could be discerned, its recent meal. Matters got a bit more predictable when a baked-bean-like object whizzed into view. This looked like, and indeed was, animal - a seed shrimp - no doubt looking for its own next meal. The scene was totally absorbing. Finally, my search revealed a semi-transparent, segmented structure which seemed to be convulsed - extending and contracting wildly. This turned out to be the last few segments of a sparse-bristled worm and whether it was in its death-throes or busy creating a new front end must remain a mystery as, by now, it was someone else's turn at the microscope. Even a relatively simple microscope can reveal so much about the structure and design of natural forms - the scales on a moth's wing, the tightly packed spores on the underside of a fern or the delicate tracery of the gills of a fungus. A really powerful instrument, showing a whole world in one water drop, really stretches the mind. [Back] |