The present invention provides a novel apparatus for culturing animal, insect, microbial, or plant cells whereby an inflated plastic bag provides a sterile, disposable cultivation chamber. The inflated bag is partially filled with liquid cultivation media and cells, and placed on rocking mechanism that moves the bag to and fro thereby inducing a wave-like motion to the liquid contained therein. This motion ensures cell suspension, bulk mixing, and oxygen transfer from the liquid surface to the respiring cells without damaging shear forces or foam generation. Air is passed through the bag to provide oxygen, and sweep out evolved carbon dioxide.