Hsing-Hsing was playing it cool and macho yesterday morning. Sitting in the panda enclosure at the National Zoo, he reached out a mighty paw, grabbed a leafy bamboo shaft three or four times his own length, bit into the middle with a resounding crunch and began gobbling the stalk like a kid with an ice cream cone.

Next door, his sometime-playmate, Ling-Ling, was nibbling a carrot with a dreamy expression on her face. She looked a little bit pregnant, but then she has looked a little bit pregnant for years.

Both seemed to have recovered from the dramatic events of the weekend.

Not so the zoo's director, Dr. Theodore H. Reed, who was giving a press conference while the panda couple frisked and gamboled outdoors.

The scene was something like a White House press conference in a moment of crisis; a nation's eyes turned toward the administration building of the National Zoological Park, and there were questions to be answered.

The key question was: Is Ling-Ling pregnant or isn't she? Reed doesn't know, and he's not sure which possibility worries him more.

Nobody will know for about 4 1/2 months whether the two attempts at artificial insemination last weekend were successful or not. The first sign (a swelling of the nipples) will not be evident until about two weeks before Ling-Ling gives birth (if she gives birth) to a cub about the size of a kitten -- four to five ounces.

"We can say that a breeding has taken place," Reed told a battery of reporters. "We're not sure about a conception.

"We're going to act as though she's pregnant, but we don't know."

"How many times was Hsing-Hsing jabbed with that hypodermic?" an investigative zoo reporter asked Reed.

"I'm not sure," the director answered. "There were so many things going on . . ."

"Will you tell us the exact dosage of the drugs you gave him?" Reed refused flatly: "The exact dosages will be published in specialized journals."

Does the nation want to know how Hsing-Hsing was put to sleep? Reed assumed that the nation wanted to know more about the complex process by which Hsing-Hsing's sperm was obtained for the artifical insemination that was attempted twice last weekend. The process is called "electroejaculation," and it was shown yesterday in perhaps excessive detail on a videotape prepared for the media.

Also detailed was the insemination process which started some 860 million panda spermatazoa on what Reed called "a steeplechase" through Ling-Ling last Saturday and Sunday. No details at all were available on whether any of those myriad marathoners encountered an ovum at the finish line.

"I feel a little embarrassed about this whole thing," Reed said into a battery of television cameras, tape recorders and notebooks. "This is a private and intimate thing between the two pandas."

If Ling-Ling does give birth to a baby panda in five months, he said, it will be done in total privacy -- except for a closed-circuit television hook up.

The artificial insemination was done in private, but the panda couple's earlier natural efforts were performed outdoors with the public welcome to observe. Reed, impressed by the pandas' ability to ignore the public, said he doesn't think the audience mattered to the honeymooners.

Like many media stars, the pandas seem to have trouble in private relationships. And like many good-looking males, Hsing-Hsing has rotten technique.

The embarrassing facts were there on the videotape for all to observe. He would stroke her, put an arm around her and try to nibble her ear, and she would slap his face.

"They have just not been able to get it together," said Reed, "so we decided to help them."

Hsing-Hsing was given four opportunities to prove himself before science took over where nature had failed.

After taking a new sperm sample through electroejaculation, the experts decided to use a more potent specimen that had been taken last year and kept frozen in liquid nitrogen.

Brandishing the harpoon-like insturment with which Hsing-Hsing was drugged into cooperation, Reed showed some of the strain of a tense press conference.

"Will one of you please volunteer," he said to the row of television cameramen, "and I'll show you how it weorks."