Almost 500 sweating, singing, backslapping '27 grads, streaks of silver in their hair, spring in their step, and wives and families in their train will officially begin their 25th reunion weeklong spree at the University today.

Elbowing and hand-shaking their way into town from 20 countries and 39 states, these members of a roaring college class will begin their riotous week soberly with memorial services for the class's 74 deceased members in Memorial Church at 4:30 this afternoon.

Then, at 6 p.m., a caravan of busses for the classmates and their wives will leave the Union for an evening of Pops, musical and alcoholic, at Symphony Hall. Their sons and daughters can also go to the party and dinner at Symphony Hall in special busses, if they have signed up for these events. For the younger children, there will be a magic show in the Union at 7:30.

Record Almost Complete

According to the Class's 25th Anniversary Report, the Class roster at graduation totaled 883 men. Of these, the fat volume has complete records on 743, and a summary note on 76. 629 photographs of classmates appear in the tome. Six of the men are "lost" according to the report.

"We are a large class," writes George O. Russell, Jr., in charge of the report's compilation, in an introduction. "Consequently, the report includes the lives of more individuals than any previous Harvard 25th report."

The seniors this evening will be making their own whoopee. Their spread, described in the schedule as "the brightest evening of the week" will begin in the Lowell courtyard at 10 p.m. to the music of Blue Barron and his orchestra. It includes a formal dance and a midnight supper, and will move lustily along until 3 a.m.