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...