WASHINGTON - One of the nation's most honored diplomats — Ralph Bunche — once sold newspapers to help his family put food on the table. During World War II, he had key intelligence assignments, and in the state and war departments. He is perhaps best known for negotiating an Arab-Israeli truce in Palestine in 1949, an achievement that earned him the Nobel Peace Prize. Ambassador Bunche helped establish the United Nations and became U.N. Under Secretary-General in 1968. An honor student, Bunche maintained close ties with higher education for his entire life, teaching at Howard and Harvard universities. Now, there are 2.5 million African-Americans in colleges across the nation, roughly twice the figure 25 years ago.