Never yet having seen one definitive production (among many) of "Uncle Vanya," I was reasonably satisfied by the version by Toronto's Royal Alexandra Theater Company, which opened last night at the Eisenhower to run through Dec. 23.

Having begun the present tour in the title role, Peter O'Toole has switched to the part of Dr. Astroy, the outsider who observes, but refuses to be drawn into, the complications of Vanya's household. I should think this a very wise move, for O'Toole's natural vitality is quite at variance with the family's general lassitude and inability to take action.

Not that this Dr. Astrov is about to take on young Sonya, who so clearly adores him. O'Toole achieves a world-weariness, even a world-sickness, which makes her passion futile. O'Toole uses the speech about how "The forests of Russia are crashing down before the axe, millions upon millions of trees perish . . . and all because man's so lazy, hasn't the sense to bend down and take his fuel from the ground."

He uses it, under the direction of Roderick Cook and Nat Brenner, as an aria addressed to our present. Looking out to the house and em- ploying that splendid, trained voice, O'Toole takes the speech and gets at the root humanity in Chekhov's compassionate view of this particular family. He is an arresting actor, the rigorous training of his youth standing him in enviable stead at this stage of a career when he must prove to be more than a handsome film face.

This accent is needed for the 78-year-old comedy which Chekhov subtitled "Scenes from Country Life."

He was writing of a complex family situation in which a fatuous, stuffy professor has compelled sacrifices from all those to whom he is related only by marriage.

It is a situation difficult to imagine from modern urban living, and when an embrace is seen by one who should not have seen it, when shots from a handgun miss their target twice, Chekhov means to be funny.

For all his characters are self-absorbed, pathetic in that absorption yet, at the same time, funny. Which is why the writer of one-act farces insisted, even of his four major works, that they were meant to be comedies.

So, from the distance of time and space and from the playwright's own style of gradually evolving layers of action and character, his audiences must work along with the players. I would prefer less stately playing for the first two acts and a great deal more of the acting vitality one finds in O'Toole and co-director Cook, who now plays Vanya.

When it comes to Act III, leading up to the shooting scene, Chekhov has made matters easier for his actor. The coughs lessen out in the house, the inner humors assert themselves, the players gain confidence and the work takes hold.

And the work itself, here in an often fresh translation from Frederick Monnoyer, is what does matter. His mixtures of color, period, people and philosophies place Chekhov planes above so many playwrights wer are forced to endure.

Jackie Burroughs is effective, if overstately, as Yelena and, rising to her moments, so is Maureen McRae as Sonya. There is that mix of accents which so often forces a glaze over Russian Originals, but I did respect Marie Kean's nurse. John Jensen's settings serve the four scenes expeditiously and tenderly.