If there were anything in terms of the movie world as certain as death and taxes are in terms of life in general, it's the iron-clad formula for Disney animated features. Tune-heavy musicals ready to be adapted for the Broadway stage, with comic relief broad enough to appeal to wee ones and grown-ups alike and happy endings calibrated for maximum crowdpleasing, The Formula has been sturdy and reliable enough to be worked year after year, like clockwork, to satisfying effect.

Though last year's _Mulan_ put their animation grosses back on the upswing, box office for Disney animated features had been in steadily decline since _The_Lion_King_'s high-water mark in 1994. Factor in the recent raising of the animation ante by DreamWorks's sumptuous epic _The_Prince_of_Egypt_ and to be further elevated, if buzz is to be believed, by the forthcoming _The_Iron_Giant_ from Warner Bros., that Disney formula--as tried-and-true as it is--is looking ripe for reinvention. And that's what the Mouse has done with _Tarzan_, a highly enjoyable adventure that takes risky devations from The Formula--and, for the most part, succeeds.

As can be gleaned from the title, this 37th full-length Disney animated feature is based on Edgar Rice Burroughs's legendary man of the apes (voiced as a child by Alex D. Linz, as an adult by Tony Goldwyn), who was raised by a family of gorillas after his parents were killed when he was an infant. Directors Kevin Lima and Chris Buck memorably cover the backstory--the arrival and settling of Tarzan's parents in the African jungle, their death at the hands (paws?) of a vicious leopard, Tarzan's adoption by gorilla matriarch Kala (Glenn Close)--with an efficient and stunningly animated prologue scored to the rhythmic Phil Collins-penned and -performed tune "Two Worlds." The song effectively conveys the primary theme of the film: that of Tarzan being caught between the world of gorillas and that of humans, a conflict that comes to the forefront when a human expedition team, including the beguiling Jane (Minnie Driver, extremely well-cast), arrives in the jungle.

"Two Worlds" is one of five tunes heard during the course of _Tarzan_, but, unlike nearly all of Disney's animated output, the film is _not_ a musical. It was a daring move, but it was a wise one. Collins's songs function well as an underscore (in terms of music and in terms of the story's themes), and in this story, to have the characters burst into spontaneous song would have simply felt odd--not to mention have been a distraction.

And that's exactly what the film's sole production number, the clumsily integrated "Trashin' the Camp," is--a needless distraction that stands at odds with the rest of the film. The song is a showcase for Tarzan's ape best friend Terk, who is voiced by Broadway's most famous fan, Rosie O'Donnell. As has been widely reported, O'Donnell agreed to do the film only if she were given a song to perform. While her involvement gives _Tarzan_ some negligible marquee name value, it wasn't worth the expense to the film as piece; it not only is out of place, it also stops the film dead in its tracks. Even worse, the number, which (as the song's title implies) has Terk and her pals destroying the humans' camp, is, quite simply, not much fun.

The same can be said for Terk and her elephant pal Tantor (Wayne Knight), the designated comic relief of the film. Plainly said, they just aren't very funny; their phoned-in small guy/big oaf routine is a poor man's imitation of _The_Lion_King_'s classic comic team of Timon and Pumbaa. I cannot think of any good reason for there to be any comic relief in _Tarzan_ other than to make a safe concession to The Formula. Surely Lima, Buck, and screenwriters Tab Murphy, Bob Tzudiker, and Noni White could have seen that there is enough situational comedy built into the story, as clearly evidenced by the hilariously, adorably awkward first meeting between Tarzan and Jane and the refined Jane's clumsiness in the wild forest.

The forest is indeed wild--and wonderfully alive--in the hands of Lima and Buck, for _Tarzan_ signals another advancement for Disney in the visual arts. _Tarzan_ is by far the most inventive Disney effort in terms of animation; the aforementioned opening is a wonder in and out of context, and with none of the restrictions present in the flesh-and-blood world, the exhilarating abandon of Tarzan's vineswinging can truly be captured in its high-flying glory. Because of the interspecies language divide, _Tarzan_ is highly dependent on facial expressions, which the animation crew has refined to an even greater level of precision than previously seen in Disney films.

I wouldn't rank _Tarzan_ among the very best of the recent Disney animation crop, but for all its shortcomings, it is still family entertainment of the highest order, with great appeal to both kids and adults. It also represents a crucial turning point for the Mouse's animation house: a brave step away from The Formula and toward a new, more varied direction for the new millennium.