Keeping a culture jar

A hay or leaf infusion gives you ciliates for weeks.

A culture jar lets you watch the same community change over days.

Making one

• Boil a handful of dry hay, grass or dead leaves in water for a few minutes and let it cool.
• Put it in a jar and add pond water or a bit of pond sediment.
• Cover loosely and keep at room temperature, away from direct sun.

What happens

Within a few days the water turns cloudy with bacteria and small flagellates appear. Ciliates follow; Paramecium is common in such jars after a week or two. Later come predators and grazers that feed on the first arrivals. A film forms on the surface: take drops from there, from the middle, and from the bottom.

Wash your hands after handling pond water and cultures, and keep jars away from food.