The present invention provides a Petri dish, especially for culturing micro-organisms, comprising a circular lower dish and a cover loosely laid thereon. Projections are formed provided on the periphery of the inner surface of the cover and, matching depressions are formed on the rim of the lower dish. This permits adjusting a gap between the cover and dish for control of gas exchange between the interior of the Petri dish and the atmosphere.
展开▼
