Several hundred people flocked to Center City on Saturday afternoon to join voices around the world in protesting genetically modified food and Monsanto, the agricultural corporation that is a leading producer of engineered seeds.

"March Against Monsanto" took place in more than 250 cities around the country, as well as in more around the world, organizers said.

Monsanto Co., based in St. Louis, said Saturday that it respects people's rights to express their opinions, but maintains that its seeds improve agriculture by helping farmers produce more from their land while conserving resources such as water and energy.

Holding signs bearing messages like "I am not a science experiment" and "Food from a lab? No thanks," the protesters began at the Constitution Center and marched along Market Street to City Hall. They ended at LOVE Park.

Melanie Douty-Snipes, part of the family that owns Snipes Farm in Bucks County, came to march with Brad Berry, a member of the farm's board.

"Food is a basic human right, and it should be assumed that it's safe to eat," Berry said. "And genetically modified food isn't safe. But you don't know that when you see an apple in a store."

Douty-Snipes said that only a nationwide boycott of products that use Monsanto products will lead to change.