The Pack Mentality : Once upon a time, book bags transported . . . books. Now, they’ve replaced lockers and desks, becoming a kid’s life-support system from daybreak to dusk.

Like monstrous tortoises, they amble down sidewalks in the early morning and late afternoon. Traveling alone, in pairs or in herds, these two-legged creatures with posterior humps infest the country, congregating in schoolyards.

Those telltale lumps?

Backpacks--the universal sign of the student.

Tiny 5-year-olds piloted to kindergarten by a parent carry them. So do swaggering high school seniors. Age may figure in the choice of a backpack, but rarely does it affect a pack’s basic contents.

For an adult, a backpack is a fashionable accessory; for a child, a daily necessity. It holds a life-support system that sustains millions of kids from daybreak till dark. They stuff their packs with sustenance, entertainment, books, paper, pens, pencils, computer discs, great literature, minor artworks, toiletries, clothes, keys, money, identification.

And, in more than a few well-publicized cases, weapons.

Children once transported their belongings to school in bicycle baskets and stashed them in a desk or locker that served as base camp. Now, bikes are often left in the safety of the family garage, school lockers are rarely used, and desks are considered community property.

The idea of schlepping things around via a pack is older than recorded history. But the species common to the United States, with double shoulder straps and a zippered case, has been around only since the late ‘60s, when Murray Pletz won a $4,000 prize from Alcoa for putting aluminum to new use in his design for a backpack frame.

Using that cash as seed money, Pletz and friend Skip Yowell set up shop in a vacant corner of a transmission shop owned by Yowell’s uncle in Everett, Wash. They arm-twisted another friend, Jan Lewis, into doing the sewing, promising to name the business after her. Jansport it became.

In 1971, the company produced its first small, frameless pack, with a dual market in mind: day hikers and college students in need of waterproof book bags. A few thousand packs were made that first year.

Jansport expects to sell 3.5 million day packs this year, mostly to older students willing to forgo fashion statements for durability. Priced from $20 to $45 in sporting-goods stores, Target and JC Penney, Jansports are the hardy, four-wheel-drive kind of packs. They’re made of leather and Cordura, a fiber manufactured by DuPont and originally intended for tires.

In days gone by, the larger the book bag the nerdier the kid, but times have changed and so have the proportions of cool.

The largest Jansport day pack is one of the bestsellers this year because students “like the technical look of a large pack,” Lewis says.

Esprit made small packs for its youngest customers, only to find that “as soon as they hit kindergarten, they want the full-size packs,” says Sarah Santa Maria, sports-accessory designer for the San Francisco company.

Backpacks have become such a staple that some of their design details are being incorporated into other bags. The more a bag functions like a backpack, the better it sells, Santa Maria says. “We’ve been making little handbags that convert to packs and drawstring bags that have shoulder straps.”

Other recent design innovations, however, speak to societal changes.

Last week, a Houston-area high school dictated that students carry see-through backpacks and purses.

“It’s a whole lot harder to conceal your AK-47 if your backpack is made of mesh,” said Gayle Fallon, president of the Houston Federation of Teachers.

Similar rules exist elsewhere, says Norman Jacobs, executive vice president of Eastpak, a Massachusetts company that has been making mesh backpacks for more than a year.

“The intent was to discourage guns and knives. A lot of school districts have imposed regulations as to the kinds of bags students can carry. In Louisiana, literally every (district) requires see-through bags,” Jacob says. “But honestly, I think it’s ridiculous. If kids are going to carry something inappropriate to school, they’ll find a way to do it.”

The Los Angeles Unified School District uses metal detectors to curb weapons on campuses but has no policies governing the transparency of backpacks.

Should that change, kids can go to Target, which sells a $9 clear vinyl pack in its children’s accessory department.

First packs, often bought years before the first day of kindergarten, lean toward movie themes. There are frequent sightings of heroes (Ariel and Aladdin), reptiles (Barney), cute couples (Mickey and Minnie, Beauty and the Beast) and literary figures (Thomas the Tank Engine).

Disney also offers, in its stores and catalogue, backpacks as entertainment: Its $14 Aladdin pack has front panels that open to form a small puppet theater, with Jasmine and Aladdin puppets-on-a-stick included.

At Coldwater Canyon Elementary School in North Hollywood, kindergarten teacher Anita Cherniack offers a guided tour through 5-year-old Claudio Torres’ pack (a bright red, blue and yellow color-blocked one):

* happy-face papers from way back (“This is schoolwork that has earned him a happy-face sticker. The kids carry them around for a long time,” Cherniack says.) * a “significant” painting * a paper-bag gorilla puppet * a paper airplane (“That skill he did not learn in my class.”) * construction paper * a good drawing of a boy * a Teenage Mutant Ninja Turtles book * scissors * an apple (“That must be for me.”) * a box of crayons * a marble * a paper on what he is thankful for (“This was for Thanksgiving.”) And . . . * an eyeball (“That must have fallen off a toy,” Cherniack says as she scrutinizes the plastic goggle eye at the bottom of Claudio’s pack.)

Because her students eat in the school cafeteria, a lunch box is not in Claudio’s pack. The others have similar items--papers of honor, art supplies, prized drawings and snacks--but none rivals Claudio’s for quantity of goods.

Stickers that Cherniack awards for excellence often customize the packs’ exterior. “They wear them like badges,” she says. “They are very proud of learning.”

By junior high, students have shunned the Hollywood themes for bags that make a personal statement. Kente- and serape-inspired fabrics and hand embroidery are popular. The autographs of friends and cryptic scribblings are also prevalent. At this age, many students are moving into the bland but utilitarian packs that can withstand a heavy book load.

At Madison Middle School in North Hollywood, an orientation day is held every spring for students from the surrounding elementary schools. A backpack fashion show is part of the junior high indoctrination.

“We show them about 10 different styles of bags, from sport sacks to one-shoulder models. We borrow them from the student government, the student store and bring some in from K mart. We show them the backpacks and explain why it is necessary they have one,” says Joanna Kunes, the school’s principal.

One look inside the multiple packs of Joseph Tran tells the story. He arrives at school on a recent Monday morning only seconds before the bell with two bulging backpacks containing:

* six textbooks * several notebooks * report folders * gym clothes * computer discs * a library book

The contents easily tip the scale at 30 pounds. But because Madison students may not use the lockers that line the corridors, Tran carries a full load.

Although the school generally provides a textbook for each student to keep at home for assignments and another for classroom use, it comes up short in copies for advanced classes.

“The packs are quite heavy,” Kunes acknowledges. “Some of our fast-track students have to carry as many as five textbooks every day.

“We quit using the lockers three years ago, for budgetary and safety considerations,” she says, adding that the move also eliminated the locker area as a noisy, disruptive gathering place.

“It provided a better campus climate,” Kunes says. “And using metal detectors, it is easier to search a school full of backpacks.”

Seeing the load some kids carry is disconcerting--such small bodies, such big packs. But the weight doesn’t seem to cause physical harm, says Dr. Stephen Schopler, a pediatric orthopedic specialist at the Southern California Orthopedic Institute in Van Nuys.

“It’s pretty shocking how heavy their bags are. I see a lot of kids after school, and I’ve felt the heft of their bags. But I have seen no injuries or heard any complaints due to backpacks,” he says.

“If anything, backpacks may alleviate the poor posture and round shoulders you find in many junior high school students. Backaches are not uncommon in this age group, but (they are) usually caused by a combination of rapid growth and bad posture.”

Backpacks have become permanent extensions of students by the time they reach high school. They can’t imagine not carrying one.

“A purse you can put down anywhere and lose, but you won’t forget your backpack,” says Gaudy Gonzales, a North Hollywood High School junior. “No way,” she says, shaking her head adamantly. In her plain black nylon pack are books and notebooks, a hairbrush, makeup, hair scrunchies and hair spray.

Even though North Hollywood High students may use lockers, many still fill their packs to bursting.

Eleventh-grader Jamilia Adams stuffs her nondescript dark red pack with one textbook, one notebook and a traveling library: “Atlas Shrugged,” “Uncle Tom’s Cabin,” “Red Badge of Courage,” “The Witching Hour” and poems by Maya Angelou.

Sophomore Mary Gevorkian carries the ubiquitous Jansport pack. In it is makeup, a jacket, notebook, two textbooks, socks, gym clothes and a library book.

Some people have found packs to be habit forming. Rene Maza, a history teacher at Madison, began carrying a pack in college. Twelve years later, he drags his lunch, books, umbrella, pens, pencils and calendar around in a purple and black print backpack.

“I’m not the briefcase type,” he explains. Wearing a backpack and going to school have become inseparable. But he can go without his pack if he has to. “I’m OK (without it) off campus,” he insists.