As passers-by stared quizzically, Jonathan Lefkowitz of Goshen, N.Y., sat inside a metal cage on the sidewalk outside Harvard Yard, with a pad of paper resting on his lap and a spark of anger in his eyes. A sign on the cage announced he would remain silent for 100 hours.

He and three other animal rights activists are kicking off a week of protest against Harvard and MIT animal researchers by spending the rest of the week cooped in their cages at a very public intersection in the Square.

The activists are a small part of a much larger group of protestors, organized by Animal Defense League Boston (ADLB), who have pressured both universities for months to change their policy on using primates for medical and experimental psychology testing.

"I am sitting in this cage in protest of the 1,500 primates that are experimented on at Harvard," Lefkowitz wrote to reporters on a pad of paper.

Lefkowitz and the other protestors allege that the primates are restrained unnecessarily, that they are deprived of food and water, infected with diseases and "are left in there own feces."

But Harvard officials and scientists have repeatedly denied these claims, saying the animals are treated ethically.

At 6 p.m. last night, the four caged protestors were joined a chanting crowd of at least 50, kicking off a week of demonstrations.

Those protestors began the evening at MIT, marching down Mass. Ave to Harvard Square.