The National Zoo's giant panda cub got his fourth physical exam yesterday and promptly demonstrated what legions of pandacam viewers already know: He is healthy and continuing to develop at a rapid pace.

Robust and squirmy, the 7-week-old cub weighed 6.2 pounds, an increase of two pounds since his exam Aug. 18 and a jump of more than four pounds since zoo staff first weighed him Aug. 2.

Lisa Stevens, an assistant curator, said the cub was fidgety during the 12-minute exam. This was a distinct departure from more docile behavior earlier this month, when he slept while zoo staff weighed and measured him and took his vital signs.

"He was crawling on the table today, and we had to keep a hold on him," she said. "When I was putting the tape measure over his little head, he kept bobbing his head and kind of protesting."

The head movements, Stevens said, made it hard to get a full body measurement. So she, Suzan Murray, the zoo's head veterinarian, and keeper Nicole Meese had to settle for knowing the length from the base of the head to the tip of the tail -- about 10 inches, which is three-quarters of an inch longer than the last exam.

The cub also measured 13 inches around his chest. That's about an inch bigger than the previous exam.

"His little eyes are open, and he can see what's going on," Stevens said. As the cub becomes more mobile and gains more control over his movements, the zoo staff will have to adjust its examination techniques, she said.

"We've already purchased bigger containers for weighing him," she said.

The cub squealed once during the exam. The noise caused his mother, Mei Xiang, who was separated from the cub, to become a bit anxious. She tried to squeeze through a small opening in the door, but was lured away when keeper Brenda Morgan called to her and offered fruit.

"This was really positive for us," Stevens said. "She's interested enough in us and food that we can distract her."

Stevens also noted that Mei Xiang left the cub for more than three hours Monday night and slept on the rock work in the indoor exhibit -- the longest period she has rested away from the cub.

The cub, conceived through artificial insemination and born July 9, is the first of this endangered species to be born and survive at the zoo in its decades-long quest to help breed giant pandas. He is the first offspring of Mei Xiang and father Tian Tian, who arrived at the Panda House from China in late 2000 on a 10-year loan from China.

The zoo is paying China $10 million in privately raised funds for the panda pair and $600,000 for the cub. The money is earmarked for conservation projects to save the animals in the wild.

Under the agreement with China, the cub is the property of that country and will be sent there after his second birthday.

Following Chinese custom, the cub won't be named until he is 100 days old. The Friends of the National Zoo, the zoo's support organization, is holding a contest on its Web site in which the public can vote for a favorite name among five approved by the China Wildlife Conservation Association. More than 66,000 votes have been cast.

The cub won't go on public exhibit until the fall at the earliest.

The zoo's live webcams from the Panda House have been flooded with fans trying to watch Mei Xiang and her cub. Access was limited to about 600 people at a time, or the surge of panda lovers would overwhelm the bandwidth available to the Smithsonian Institution.

Matt Olear, a spokesman for FONZ, said the Smithsonian is conducting a test to see whether pandacam traffic -- more than 2.4 million visits since the cub was born -- can be accommodated by an off-site contractor to increase Internet access. In the meantime, the Animal Planet Web site also has a link to the zoo's pandacam.

For links to webcams of the panda and more information, go to www.washingtonpost.com/metro.

Suzan Murray, the National Zoo's chief veterinarian, examines the 7-week-old panda's ears while Assistant Curator Lisa Stevens holds the feisty cub still. "His little eyes are open, and he can see what's going on," Stevens said. Behind them is keeper Nicole Meese.The cub "was crawling on the table today, and we had to keep a hold on him," a curator said.