About 200 M.I.T. students, chanting "Cuba 81, Castro No" and a slightly incongruous "We Want Latin," Invaded the Yard at about 11:30 p.m. last night.

After a march around the Yard falled to enlist substantial support from Harvard freshmen, the Engineers prostrated themselves before the status of John Harvard and then left by the PBH gate. The demonstrators were greeted at the MTA entrance by a squad of riot-trained Cambridge policemen, who herded them into the subway and waved happily as they departed.