The little bundles emerge from stage right, usually (but not always) in the arms of an obstetrician. Four are wrapped in blue blankets, one in pink. One is tossed in from offstage. All five land on the ground with an amplified thud. All but one is a corpse.

Christopher Durang had broached the subject of dead babies before his 1985 pitch-black comedy “The Marriage of Bette and Boo,” now receiving a potent if occasionally wobbly revival at the Roundabout. The title character of his “Sister Mary Ignatius Explains It All for You” confirmed the purgatorial status of billions of unbaptized children without batting an eye. But the stillbirths that he milked for laughs in “Bette and Boo” are different in one crucial fact: They are — or would have been — his younger brothers and sisters.

Mr. Durang has called this play his most unabashedly autobiographical work, from the alcoholic father (Christopher Evan Welch) to the heartrendingly ill-equipped mother (Kate Jennings Grant) to the blood incompatibility that doomed all but one of their children. The author even played the surviving son in its premiere. (In a strangely touching act of dramatic license, he afflicted his onstage mother with an additional stillbirth beyond the three that she actually had.) But while director Walter Bobbie offers a tightly paced glimpse into the punishing childhood of the author’s surrogate, here named Matt (the agreeable Charles Socarides), he relies too heavily on the dazzling light of the play’s goony construction, flitting around some of its more superficial conceits without forcing his way into the darker corners that Mr. Durang explored only reluctantly.

Mr. Durang pioneered a distinctly American gloss on the Joe Orton template, replacing Orton’s cultural antecedents — tried-and-true populist stage genres like whodunits and sex farces — with his own boisterous mixture of pop-culture detritus, highbrow name-dropping, agonized self-examination, and wry distillations of familial turmoil. (“You know, you’re the only one of my children that lived,” Bette says to a college-age Matt at the beginning of a visit. “How long can you stay?”) This blend has proved remarkably potent: TV’s “Six Feet Under” mined it profitably for five seasons, and younger playwrights like Noah Haidle (a former pupil of Mr. Durang’s at Juilliard) and especially Nicky Silver have gone on to carry the torch.

In fact, these subsequent efforts have built upon Mr. Durang’s occasionally glib example. From a priest imitating bacon in the middle of a pre-Cana tutorial to the continued presence of Bette’s father after his death (albeit shrouded with a bedsheet), “Bette and Boo” parcels out its lunacy alongside but not always in harmony with its more somber moments. The scars and the smiles alternate instead of overlapping.

Mr. Bobbie adds to this sense of bifurcation by having most of the actors toggle gamely between wacky absurdism and plaintive drama. A typical friction can be found among the two strong actresses who play Bette’s sisters, as Zoe Lister-Jones aims for the funny bone as the brittle Joanie while Heather Burns locates the fragility of the perpetually apologetic Emily. Mr. Welch and Ms. Grant balance the two poles more comfortably, although each errs on the side of pathos; as Boo’s toxically dysfunctional parents, by contrast, John Glover and Julie Hagerty are both very funny (with some assistance from Susan Hilferty’s costumes) but neglect the few resonant moments that Mr. Durang gave them.

There are two notable exceptions to this either/or quality. Terry Beaver sparkles with a malevolent gleam both as the baby-dropping doctor and as the ineffectual priest, settling into a raspy baritone that manages to sound both sage and in on the joke. And the increasingly indispensable Victoria Clark, not content to remain merely the most emotionally honest and technically impeccable performer in today’s musical theater, displays note-perfect wit as Bette’s mother, a chipper monster who wears her malice and neediness on her well-appointed sleeve:

“Sometimes I’m afraid if I had to choose between having my children succeed in the world and live away from home, or having them fail and live at home, that I’d choose the latter. But luckily, I haven’t had to choose!”

With the one obvious exception, Bette and Boo were not given such a choice. One of Mr. Bobbie’s subtler directorial touches comes as the expectant family members shuffle off after each stillbirth crumples to the ground. In each case, Boo lags behind and then tenderly picks up the inert bundle before trudging off. In each case, that is, except the fourth and final one: Not even the weak, self-destructive Boo can bear to hold another dead baby. Has Boo reached the limits of his own compassion? Or is Mr. Bobbie undoing Mr. Durang’s “extra” stillbirth in an attempt to restore order to a world that cannot — indeed, that should not — accommodate it?

Until September 7 (111 W. 46th St., between Sixth and Seventh avenues, 212-719-1300).