Hippie Happenings : Fashion: Marc Jacobs deconstructs the ‘60s and ‘70s for the Perry Ellis spring collection as New York designers plunge into the latest wave of nostalgia.

There is definitely something happening in the New York fashion world this season.

But it’s not what most observers would predict.

Marc Jacobs, the man behind the Perry Ellis collection, is pulling ahead of a pack that includes cutting-edge designers Isaac Mizrahi, Todd Oldham and Christian Francis Roth.

Jacobs, 29, started at Ellis four years ago. Since then it’s been a checkerboard trip toward the top. One early collection had Timberland life vests and hiking boots. Then came garden-print dresses and gingham check suits.

Last season, his Carnaby Street-inspired show--with high silk hats, Beatle coats and python pants--struck a nerve. It was part rave / part hippie retro, and his timing was perfect.

This time, Jacobs dug deeper, and came out with a completely American version of a controversial dress style that is being shown by young experimenters in every major fashion city worldwide. The look includes unfinished seams worn on the outside, shredded “ribbon” skirts that resemble carwash curtains and sleeves that dangle unbuttoned below jackets.

This is deconstructivist dressing. The architectural term gets tossed around freely in fashion circles these days and has everything to do with tearing down tradition.

Jacobs showed black body-hugging dresses with cutouts at the midriff or just below the waist in back that had a raw, unfinished edge. Other dresses had exposed shoulder seams.

But Jacobs did more than turn dresses inside out; he deconstructed dress codes. Garments didn’t quite go together the way you might expect.

There are fruit-print jackets, bra tops and pants, taken from American folk art, in this line. But Jacobs mixed them like a fruit salad. He showed pear-print pants, a cherry-strewn bra top and a jacket to match. For starters. Then he pushed the deconstructivist concept even further with homeboy flannel shirts--actually, his were silk--worn unbuttoned over the bra tops under the jackets.

Striped watchmen’s knit caps--a staple of grunge fashion--were matched with flimsy floral print dresses and aggressively tacky Naugahyde car coats from the worst of early ‘70s dressing.

Girls with dirty, stringy hair decorated with rhinestone barrettes conveyed an out-of-it, irresponsible air that seemed to be the heart of this late hippie fashion revival sweeping the world for spring.

Of course, ‘60s hippies dressed cheaply, in thrift-shop costumes, to show off their childlike hopeful vision for the future. This time, the clothes represent escapism--a vote of no-confidence in the future. It is a make-the-world-go-away fashion movement.

Jacobs didn’t invent it, nor was he the first to capture it. But he did make the movement his own, in a way both exciting and unsettling to see.

During this week of spring previews by New York fashion designers, which continues through Friday, his take on the fashion scene will be hard to match.

Elsewhere, originality appears to be at a premium.

The day Carolina Herrera shows a fashion collection of elephant-leg pants and bra tops, you know everybody’s doing it. She never was--nor wanted to be--a trendsetter.

Several seasons ago, Herrera’s idea of a Harley-Davidson fashion revival was a satin motorcycle jacket sprinkled with rhinestones. Grunge by Herrera’s definition is a gold-beaded top over gray flannel pants.

She stands for blue-chip conservatism with a capital C . So her fashion show on Monday sealed a deal about dressing like no other show could: Put your money on hippie rehab.

Even the most guarded of the old guard American designers are getting caught up in the wave of early ‘70s nostalgia that has rolled in from Milan through Paris and is spreading across the New York fashion scene.

The worst of the revival has to be those hip-hugging, bell-bottom pants that cling to the knees, then flare to the floor like umbrellas in the wind. Herrera showed them in white with navy blue piping.

The best of the look are some mid-thigh link tunics, usually worn over cropped, narrow pants. Herrera showed them with cut-in shoulders and discreet slits on the side.

You didn’t see Ivana Trump parading around in bell-bottoms. After Herrera’s show (she and Jackie Onassis are customers), Ivana stopped long enough to show off her navy blue pantsuit with a waist-nipping jacket. She’s still has the hair--blond bangs, teased top and French twist, if not The Donald.

Hair was the most striking thing about the Bill Blass show. Models wore flat, ironed bangs with sideburns.

Blass did his trademark mix of day and evening fabrics--wide-leg glen plaid pants and a matching vest with a sheer lace back, for example. A mock crocodile tunic went with sheer, leopard-print pants. Pants worked better in Blass’ collection than skirts. He went for the mid-calf wraparound look in skirts, slit in back with a stiff artificial look.

Hippie hostess outfits made sense as a way for his Republican clients to get in on this season’s costumery. The outfits included a sheer abstract-print coat with string ties at the bodice, worn over slim, silk pants.

At least Nicole Miller did hippie her way--cheaper. Her prices are less than half those of the high-end collections. She beaded some fringed sarongs and bra tops, vests and skinny, long dresses for showstopper effect.

Miller’s tuxedo with stovepipe pant legs (straight to the floor and medium-wide) looked new, worn with a cropped tie-front blouse. And her tile print vests and sheer pants, beaded and fringed like lampshade, resembled Shirley MacLaine’s wardrobe from the film “Madame Sousatzka.”