Science: Magnified Pond Scum

Under the microscope a drop of pond scum can give hours of delightful study. What feels between the fingers like slime is, microscopically, an open lake crowded with queer vegetable and animal life.

The Dutchman, Anthony Van Leeuwenhoek (1632-1723), who invented the microscope, spent the last 50 years of his life studying and describing biological scum. Others have extended his work, until now scientists have a very wide knowledge of what lives on earth.

Those not scientists, however, have only a skimpy idea. So, since natural history museums should educate as well as collect, the American Museum of Natural History in Manhattan had Curator Roy Waldo Miner reproduce in wax and glass a cubic half inch of pond life. The exhibit was opened to the public last week.

All things in the water are magnified 100 times, or cubically a million times. What is silky green scum in ponds of spirogyra, is reproduced as great, slender stems with tubular strands. Water thyme has slender pointed leaves and graceful translucent green stems. Bladderwort carries little traps at the ends of stems. Really they are the size of pin heads. Enlarged they are three to four inches in diameter. When an animalcule touches the bladder (utricle) a flap snaps upwards; the beastie slips into the pouch; the trap springs shut.

Of pond animal life reproduced at the Museum there are water fleas, protozoa (single-celled animals), insect larvae, and rotifers. The rotifers, most interesting, give their name to the entire exhibit. The commonest kinds are shaped like tops. The rotifer head is round and surrounded at the flat shoulder with fine cilia which vibrate (in life) so rapidly one after another around the circle of shoulder that the whole body seems to rotate. They are voracious and pugnacious, crouching on a microscopic plant and then swiftly springing at a stray water flea, a protozoa, a bit of leaf.