In jest

The Farrelly Brothers are back—after a dismaying run of excruciatingly pathetic attempts to re-attain the gross-out heights of Kingpin and There’s Something About Mary—with this altogether odd hybrid of live-action and animation.

The live-action sequences that introduce us to slovenly zookeeper Frank (an astoundingly unselfconscious turn, even for him, from Bill Murray) aren’t entirely successful. But when Frank chows down on a tainted hard-boiled egg, the paint hits the fan as the animation kicks in and Osmosis explodes into rambunctious life, switching gears to become a surreal “This Is Frank’s Plumbing” for the kiddie set (although, like most “family” films of late, most of the jokes will go about 10 feet over the young’uns heads).

Chris Rock smacks wise as the voice of the titular character, a white blood cell teamed with a Buzz Lightyear-esque cold tablet (David Hyde Pierce) to defend Frank’s immune system from a deadly virus (Laurence Fishburne in a smooth and demonically perfect turn as the evil Thrax). As the mismatched partners pursue the villain through the teeming organic metropolis, from the cerebellum city hall through the sewers of the bowels (and so on), Osmosis actually works as a rudimentary primer for the kids as to how the human body works … and what happens if you don’t eat your vegetables, hint, hint.