Deep in the rainforest, the adventurer snipped leaves off a curious looking plant and carefully placed them in a container before moving on to the next strange and wondrous living thing.

He pulled up roots, gathered berries, picked mushrooms and scraped mold off of leaves.

The samples all were sealed inside jars and transported back to the United States.

For decades, pioneering scientists traveled the world, gathering samples for researchers at Merck & Co. to reproduce and analyze in their search for new medications to treat the ills of mankind.

“This collection was built by scientists going around the world, finding the interesting plants, finding the specific bacteria and bringing them back,” said Dr. Roger Pomerantz, of Merck. “It was built over decades and is a seemingly limitless resource.”

And now, that vast library of the world’s plants and microbes will find a new home just outside of Doylestown.

Merck & Co. is donating its library of natural products to the Institute for Hepatitis and Virus Research. Headquartered at the Pennsylvania Biotechnology Center of Bucks County on Old Easton Rd., the institute is the research arm of the Hepatitis B Foundation.

On Monday, scientists and administrators from the center joined Merck representatives to celebrate what amounts to a windfall for the institute.

The donation also helps solidify the growing field of biotechnology research in Bucks County, said State Sen. Chuck McIlhinney. The biotech center near Doylestown is a boon to all of Bucks County, he said, by offering high-tech, well-paying jobs and drawing bright scientists to live here.

Merck’s natural products library is considered one of the most diverse and professional of its kind in the world, said Dr. Timothy Block, president of the Institute for Hepatitis and Virus Research.

It represents 60 percent of all known plant genera in the world, and includes 100,000 samples all prepared and ready for use in research.

The library is expected to be delivered in all its test tube glory within about three months, Block said. A new entity, the Natural Products Discovery Institute, will be formed to administer the collection, he said.

Pomerantz, who has lived in New Britain Township near Peace Valley Park for 22 years, said Merck started looking for a repository to donate the library to about a year and a half ago.

By then, Merck had decided to focus almost exclusively on developing medications from man-made molecules, rather than natural ones, he said.

“You have to focus on one thing to do it really well, rather than doing a lot of things,” said Pomerantz, who is a senior vice president at the pharmaceutical company. “We decided to focus on synthetic molecules.”

Donating the collection to a small biotech group was in keeping with the best practices of scientific research, Pomerantz said.

“Biotech and large pharma need to work together,” he said, as executives milled around the Biotech Center Monday morning. “They both do certain things well. This will combine that small company passion with large company power. We think it’s a good model for the future.”

Once at the institute, the samples will be made available for other researchers to apply to use, said Block, who sported a tie emblazoned with an image of the Hepatitis B virus identified in 1967 by Dr. Barry Blumberg.