The National Zoo has concluded that Ling-Ling, the giant female panda, is not pregnant. As a result, the popular Panda House, closed to visitors last month so that Ling-Ling would not be disturbed, will reopen Nov. 1, a zoo spokesman said yesterday.

Ling-Ling was artificially inseminated last spring after she and her male companion, Hsing-Hsing, failed to mate naturally. Zoo officials said they are prepared to try artificial insemination again next spring.

"We felt like we had a pretty good chance," said Mike Morgan, the zoo spokesman. "We caught her at the right [ovulation] time, and we had good, viable sperm, but it just didn't happen."

Morgan said that Chinese zoos are the only ones that have successfully bred pandas through artificial insemination, adding that "they have tried more times than we have and they also have more pandas to work with."

Ling-Ling, he said, is only 10 years old and capable of reproducing for several years.

"Don't count Hsing-Hsing out. We may put them back together next spring and they could hit it off," Morgan said.

The giant panda is an endangered species. Only about 1,000 are left with most of those concentrated in China's Sichuan Province.