To hear this tale, enter a world of the dead: Past laboratories hung with tiger skins . . . up twisting stone stairways . . . past boxes of bones, and metal cabinets dabbed with arsenic to keep bugs from half a million animal pelts . . . to "the Attic," a vast chamber dimly lighted at one end, its ribbed roof supports receding into darkness, where, row upon row, lie the skulls of the great elephants: Loxodonta africana. "Th. Roosevelt. British East Africa. Sept. 1, 1909," says the tag on one. Just beyond that are the cracked, yellowing tusks of what was once the greatest elephant of all: "Angola: 48 km NNW of Macusso. 17 19'S, 21 4'E. 13 Nov. 1955. J.J. Fenykovi."

After Fenykovi, a Madrid businessman, gave the Smithsonian the pelt of the largest land animal then on record, the elephant was reconstructed by a team of specialists in one of the most ambitious projects in the history of taxidermy. It took 16 months.

The original tusks--each about seven feet long and weighing 90 pounds--were removed and placed in storage for study. For the mounted display, duplicate tusks were cast from rugged celluloid plastic and secured to the wood-and-steel frame inside the hollow, mounted animal.

On March 6, 1959, the Fenykovi elephant, which alive had weighed 8 tons and stood 13 feet 2 inches at the withers, was unveiled in all its savage glory in the rotunda of the Smithsonian's Museum of Natural History. There, ears flared, trunk raised, Loxodonta africana is frozen forever in a brisk trot.

The tusks were so realistic that no one seemed to care that they were fake.

Now, however, the fake tusks are cracking, rotting from the inside out. "They're just falling apart--they're exploding," said Frank Greenwell, the last professional taxidermist left at the Smithsonian.

So Greenwell, a mild-mannered fellow in a white scientist's lab coat, is planning to change the tusks. A new set has been made and is ready for installation. Greenwell plans to set up a scaffold around the elephant's head and, armed with drills, chisels, saws and a special drill that foresters use to drill plugs of wood out of trees, begin the task around the first week of March.

It should be one of the best shows in town.

"We've tried many times to repair them," said Greenwell, "but they're falling apart from the inside. What we're going to do, we're going to cut them off four or five inches from where they insert into the animal. Then we'll chisel out the tusk, working up into the cavity so we'll have it hollow enough to insert the new tusks. The trick is to remove the tusks without damaging the skin around them."

This done, however, Greenwell will face a major problem: how to attach the new tusks securely. "The problem we have is being able to attach them up into the skull in a solid enough way in case a tourist swings on 'em, is what it amounts to. We've actually had people do it. It's that strong."

In the original construction, the tusks were attached firmly to the interior framework before forms cast in the shape of the elephant's head were put in place. The taxidermists had plenty of room to work.

After attaching the tusks, they crawled up inside the body--made of forms cast in the shape of the elephant's body over which the hide was to be stretched--through a trap door in the belly, pulled the two halves of the head into place, and secured them from the inside.

"You could walk around inside the elephant just like the Trojan Horse," Greenwell said. Now, however, he is reluctant to cut a new trap door in the belly because of the damage it would do the elephant's skin. And once inside, he still might not have enough room to do the job right. The halves of the head cannot be disassembled without doing serious, perhaps irreparable damage.

So what to do? Greenwell says he doesn't know. He's going to get up there on the scaffold and, like any good renovation expert, play it by ear.

He doesn't relish the idea of working in full public view. Two years ago, when he undertook a similar project to repair some cracked skin on the elephant, "I was probably photographed more than Cary Grant. I had people flooding around me by the thousands watching me do this restoration. It's like putting yourself on exhibit."

The realistic appearance of the fake tusks is due to painstaking effort. A cast was made of the real tusks, and inside its halves the celluloid plastic was painted in, built up layer after layer.

"Skin, or anything in nature, has a translucent look," Greenwell said. "Have you ever noticed how you look into things? They're three-dimensional." The tusks thus have a texture and depth that could not be achieved by a layer of paint on the outside. The new ones will be reinforced with fiber glass to last longer than the ones being replaced.

Greenwell and the Fenykovi elephant go back a long way. As a young man fresh out of St. John's College in Annapolis, Greenwell helped in the original mounting of the animal nearly three decades ago. At the Smithsonian, he learned taxidermy--which he describes as an art, a trade and a science--under the greats in the field, William L. Brown, Norman Deaton and Watson Perrygo.

These men, during the 1950s and early 1960s, had helped revolutionize the public's concept of what a museum could be. They took the natural history museum's animals out of row upon row of glass cases, adding larger animals such as the elephant, and displaying all of them in natural positions and settings.

Greenwell loved it all: "I was the crazy kid on the block who went around with the larvae of insects and studied spiders."

When the museum's new look was unveiled in the mid-'60s, the old taxidermological pros retired, leaving Greenwell to maintain the exhibits. In addition, he now helps prepare and maintain the museum's hundreds of thousands of "study specimens"--the skins, skeletons and guts of birds and other animals that are filed in 3,000 metal cabinets and innumerable jars of alcohol for study by scientists who come from all over the world.

The nation has plenty of taxidermists, said Greenwell, but most of them are of the "strip 'em and stuff 'em" variety--the folks you go to with the deer you shot to have the head mounted. These days, he said, "museum-quality taxidermists are few and far between."