Groucho Marx was once asked, in an interview about comedy, to articulate the difference between an amateur and a professional. An amateur, he said, thinks it’s funny to dress a man up as an old lady, put him in a wheelchair, and give the chair a push that sends it rolling down a hill toward a brick wall.

Fair enough. We’ve all laughed at some incarnation of that joke. And

a professional?

For a pro, said Groucho, it has to be a real old lady.

By that estimation, Nicky Silver is a pro. In his raucous comedy Pterodactyls, which a spiffily renovated Source Theatre premiered last weekend in a beautifully cast production, Silver packs orphans, alcoholics, delusional parents, AIDS sufferers, neurotic brides, and victims of bad face-lifts, false hopes, and sexual abuse into his wheelchair, and pretty much shoves it off a cliff.

The result is every bit as cataclysmic as you might expect, and much, much funnier. Silver’s setting is the aggressively dysfunctional home of the well-to-do Duncan family, from which Emma Duncan (Katie Barrett) is determined to escape, and to which her brother, Todd (Christopher Borg), is returning after a long absence. Emma’s a borderline hysteric—pathologically forgetful (“Facts run through me like Chinese food”) and convinced, despite persuasive evidence to the contrary, that she’s an only child.

She has selected Tommy (Jerry Richardson), a waiter at a strip-mall Salad City, as her ticket out of the family and brought him home to meet the folks. Tommy has issues of his own—mostly having to do with quality time spent with priests at the orphanage where he grew up—but being anxious to please, he’s an ardent, if unorthodox, suitor. “You smell like wet feathers” is his idea of a compliment.

Emma’s alcoholic mom, Grace (Kerry Waters), who is having trouble with her latest face-lift (“One eye is tighter than the other, so everyone thinks I’m winking at them”), isn’t convinced that Tommy’s a good match for her daughter. On the other hand, she’s sure he has the makings of a fine maid if he can squeeze into the short-skirted uniform left by the one who just departed. (He can.) Emma’s dad (Conrad Feininger) finds Tommy’s presence unsettling but has other things on his mind, among them trouble at the bank, where his presidency is in peril, and delusional relationships with his children, whose childhoods keep blending with his own in his memories. He’s also not fond of the dinosaur skeleton Todd is constructing on the family hearth, from bones he’s found in the backyard.

Todd’s three-word announcement—”I have AIDS”—is the catalyst for the crumbling of this household, though at first it seems to have little effect. Mom just proceeds with plans for Emma’s wedding (“a bacchanalian carnival of rapacious consumption”), Tommy keeps dusting, and Dad redoubles his efforts to bond with his daughter (who panics at his touch) and his son (whom he calls “Buzz,” for reasons no one can recall).

Still, disintegration is in the air, and by the middle of Act 2, death or madness has overtaken nearly everyone, with no appreciable loss in hilarity. Silver has always been deft at bringing out the humor in familial horrors, and Pterodactyls finds him in peak form, whether he’s contemplating filial ties that blind or coming up with a situation in which “This won’t involve harnesses or holy water?” qualifies as a punch line.

In Michael Russotto’s antic, sharply acted production, the decline and fall of the Duncans resembles a shotgun marriage between The Glass Menagerie and The Skin of Our Teeth as it might be envisioned by the producers of Mad TV. The performances are outsized but recognizably real, with an edge of poignance that makes the final moments of the play deeply affecting. I kept writing the word “vulnerable” in my notes, to describe everything from the catch in Waters’ voice when her character is caught pouring scotch over her cornflakes to Richardson’s sweet anxiety over the appearance of his maid’s uniform. Barrett brings a winning touch of Carol Burnett to Emma’s hysteria, and Feininger’s addled patriarch is at once disengaged and ferociously needy. The production’s linchpin, not to mention its conscience, is Borg, who is doing the best work of his D.C. career as Todd, getting laughs all evening while walking a fine line between stoicism and abject terror.

Jos. B. Musumeci has placed his serviceable living-room setting at a slight angle, partly to indicate that the Duncan household itself is askew and partly to show off Source’s nifty new black-box auditorium. Several hundred thousand dollars and many months of labor have been spent in turning the 14th Street corridor’s first theater into its newest theater. The result is an inviting, low-ceilinged space in which the absence of columns frees up Source’s sightlines without compromising the intimacy that has always been a hallmark of the company’s work. The theater could hardly wish for a better opening attraction than Pterodactyls, which should pack audiences in for the foreseeable future.

The Groucho anecdote with which I began this article comes from a Walter Kerr tome titled Tragedy and Comedy, which argues that the distinctions between those two dramatic forms have never been quite as precise as we generally assume. Tragedy, notes Kerr, is the form that holds out the promise of a happy ending, though it finally reneges on that promise by imposing a brutal, preordained order on events. Comedy, which we think of as upbeat, nearly always concerns chaos, violence (either social or personal), and disorder. Comic endings tend to make a mockery of the events that go before them. When there’s a wedding at the curtain call, we know it’s just an authorial convenience. The couple that’s been bickering for three hours will go on bickering after the honeymoon. You can’t change human nature.

It’s rare that you find a true tragedy or comedy, anyway; both forms prove mutable over time. Look at what’s happened to Shakespeare’s cruelly comic Merchant of Venice, which directors and actors have reinterpreted in the past two centuries as the tragedy of Shylock, a socially despised Jewish moneylender who demands his pound of flesh when a debt goes unpaid and is thereafter stripped by Venice’s Christian majority of everything that gives his life meaning.

Elizabethan audiences, for whom Jews were a commonly assailed other, could be expected to regard this plot line as providing just deserts for an irredeemable monster, albeit one for whom Shakespeare provided a self-justifying speech (“Hath not a Jew eyes”) or two. They would, in other words, have seen Shylock’s downfall as a happy ending for Venetian society. Modern audiences, though, can’t help seeing Venetian society as viciously anti-Semitic, and Shylock as a hapless (if not altogether blameless) victim—which rather changes the stakes. The play thus becomes a tragedy at center.

The problem with this interpretation has always been that Shakespeare dispenses with Shylock at the evening’s three-quarters mark and spends the balance of the play making jokes about cross-dressing women and mistaken identities, after which he packs everyone off to a banquet. Played as denouement to a tragedy, these scenes have a decidedly acrid taste.

Michael Kahn’s solution, in his smartly designed and executed production for the Shakespeare Theatre, is to keep reminding audiences that anti-Semitism was hardly the only viciousness of which the Venetians are capable. Frankly racist, they treat their African servants shabbily, cuffing them as they might cuff dogs. They sneer at women when they’re not wooing them. And they’re blithely savage regarding all matters involving money. Everything about the nastily capitalist city-state depicted on the Lansburgh Theatre’s stage is hard-edged, with the possible exception of Howell Binkley’s dappled lighting.

In this society, Antonio—the merchant of the title, and the unfortunate borrower whose pound of flesh Shylock means to claim—stands not exactly apart, but alone. Kahn conceives him as a typical man of his time—a derider of Jews, a slaveholder—but also as a closeted homosexual in a society where every codpiece is all-too-obviously stuffed to bursting. Surrounded by young studs whose viciousness toward outsiders makes him guard his own reputation, Antonio (Keith Baxter) is hopelessly in love with Bassanio (Hank Stratton), the handsome Ken doll for whom he places himself in debt. Financing this glad-handing poseur’s courtship of Portia (Enid Graham) proves the merchant’s devotion, but also demonstrates the extent to which he is an alien in his own circle.

In fact, when Hal Holbrook’s upright, slyly inveigling Shylock offers his hand on their devil’s bargain, you sense something you don’t usually find in a Merchant of Venice: a strange kinship between these two antagonists. Whatever their differences, both of them have had to negotiate survival in a world that doesn’t accept them.

Kahn sees to it that levels upon levels of discrimination are on display: When the African servants are disparaged by the Venetians, they take it out on the Jews. And lower still on the social roster are the Jews who convert, as does Shylock’s daughter. Eve Holbrook plays her as a confident woman who realizes on the very instant of handing over her jewels to her Christian lover (a cackling, sharp-featured Mark H. Dold) that she’s made a terrible mistake. The director has clearly thought as long and as hard about the prejudices he’s put on stage as he has about the inventive bits of business—including a nifty musical cue—with which he enlivens the courtship scenes.

But mostly, he’s placed his faith in the actors. Holbrook is a ramrod-straight, thoroughly implacable Shylock, never more so than when he’s banging his usury scale on the court’s table after being defeated. Baxter is a wrenchingly affecting Antonio. Graham’s Portia is cagey, which means the unabashed way in which the character displays her own prejudices says worlds about the society in which she lives. Fine, too, are Teagle F. Bougere’s calculating Gobbo and Andrew Long’s repugnant Gratiano.

And should anyone harbor doubts about whether flat-out comedy can still have a place in a Merchant as dark as this one, Emery Battis’ hilariously doddering Prince of Arragon will quickly lay those doubts to rest. He gets chuckles on an entrance that finds him accompanied by a half-sized clone of himself. The chuckles turn to laughs as he puzzles out the riddle Portia’s father has posed for her suitors, and then to guffaws when he guesses wrong and lisps out a disappointed “Ith thith my pwythe?” I’ve seen the play a dozen times and never heard that line get a laugh. This time, it’s as funny as if it had been penned by Nicky Silver. Go figure. CP