The architect who drew a sketch of the pocket park in front of Holyoke Center populated it with clean-cut collegiates strolling briskly to some important engagement. He clearly did not foresee that the park would be taken over by sedentary hippies mulling over the virtues of tuning in, turning on, and dropping out.

The Harvard University police are concerned about the hippies. "The park was meant to be a thing of beauty, to be appreciated, and they are not a very pleasant sight, " says one officer. We are doing the best we can to eliminate them. We hope to put up a NO TRESPASSING 9 p.m. to 6 a.m. sign."

Nevertheless, the park has become a preserve for high school kids who can't afford to sit in the Blue Parrot all day, and for marijuana brokers who use the spot as a pot Rialto. The rich ones sport Truc-loads of mod clothes and jewelery, the poor ones flaunt their general dishevellment. In the course of a day, 200 or 300 come and go. The Cambridge cops chase everyone away at midnight.

Most of the Holyoke Center hippies are products of the Commonwealth. A few are from San Francisco, vagabonding around. These tend to be proseletyzers, and the Greater Boston hippies will see them off with some relief. "Love, Love, Love -- what a drag!" commented one Watertown hippie.

Come fall, the teeny-boppers will go back to high school, the San Franciscans will return to Haight-Ashbury, the Diggers will entrench themselves in utopian flats, and the hippie boulevardiers who remain will adjourn to the Bick.