MEXICO CITY -- The morning sun streaked across 12-year-old Eloy's emaciated face as he and his girlfriend, Margarita, greeted the new day from a discarded red velour armchair they had shared the previous night outside a Mexico City subway station.

Both yawned, squinted, then simultaneously pressed toxic, solvent-soaked tissues to their mouths, inhaling deeply.

The momentary boost from the fumes was enough for Margarita, 14, to pull herself to her feet. Then, complaining of a fever and wanting more sleep, she stumbled a few meters over to a manhole, stepping around a dead rat and descending into her "bedroom"--an old underground pipe that yeas ago had run thick with raw sewage.

The story of Eloy and Margarita reflects that of thousands of other homeless Mexican children who, experts say, are becoming more numerous and more destitute as Mexico's five-month-old economic crisis. prompted by a devaluation of the peso, deepens.

"Before the economic crisis, we used to come across two or three new street kids every week," said José Manuel Capellin, director of the Casa Alianza shelter for homeless children. "Now we see two or three new ones every day."

A senior government official acknowledged that Mexico's suffering economy has increased the signs of abject poverty.

"It is logical," he said. "The crisis brings greater unemployment, and unemployment leads to greater poverty. Poverty expels children onto the streets."

The section of rusted iron sewer pipe where Margarita crawled off to sleep is also home for 45 of Mexico City's poorest poor. They range in age from 7 to 19, spending their days begging, washing car windows at intersections and foraging for food.

At night, they escape the pain and loneliness of street life by gathering in their underground culvert. Someone collects the day's earnings and rushes off to a nearby hardware store to purchase whatever "drug" is available--chemical solvents, shoe cobbler's glue or plumber's pipe dope.

For reasons no one cares to explain,. Eloy is the group's keeper of the tissues, stuffing wads of solvent-soaked toilet paper into a plastic bottle and dispensing them to all takers.

"It makes me fly," said Guillermo, 19, as he accepted a tissue from Eloy. "I can forget everything and take a trip."

Although he described himself as a longtime veteran of street life, having left his parents seven years ago, Guillermo said the economic crisis was pushing new children to his sewer-pipe doorstep every week.

"We have to be mean to them and tell them to go away," he said.

At a nearby bus station, Manual Veloz Vite, a Casa Alianza volunteer, said new children were flocking in daily, mainly from the southern states of Veracruz, Oaxaca, Michoacan and Chiapas, which have been hardest hit by rising unemployment and poverty.

"The street children are not the problem but rather a symptom of the real problem," Mr. Capellin said. "The kids are evidence of how the system punishes its weakest members."

A 1992 United Nations survey estimated that there were 11,000 "street children" in the Mexican capital, either homeless or put on the streets by their parents to beg or work.

Now, "we think there are 30,000 to 40,000," said Mr. Capellin, whose organization operates eight shelters for children across Mexico City. He added that no nationwide estimates exist.

The children are in evidence at busy intersections everywhere in the capital. Taller youngsters jump on car hoods when traffic is at a standstill, spraying windshields with detergent and quickly wiping them clean in hopes of earning a one-peso donation, the equivalent of 17 cents. Smaller children meekly wipe side mirrors or tap the drivers' windows to ask for a handout.

At one busy intersection, Maria Camacho, a 38-year-old mother of eight, said she sends her children onto the street because "it is the only way we can survive."

Before the crisis, she explained, her older teenage boys could earn up to $15 per day washing windshields. She made roughly the same amount selling guns while keeping an eye on her two infants.

"People won't give the kids anything anymore," she said. "We make half as much as we used to."

For those like Eloy and Margarita without parents to watch over them, the tough times are leading to increasing acts of desperation. A few months ago, Mr. Veloz said, Margarita tried to commit suicide by slamming her head repeatedly into a concrete wall. She has also slashed her wrists at least twice.

While entertaining two reporters inside his manhole home, Eloy extended his own wrist and asked an aid worker to put a bandage on cuts he had made the day before.

"I did it with some broken glass," he explained.