James Bryant Conant, a former president of Harvard University and an educator whose ideas had a profound influence on high school and college programs throughout the United States, died Saturday in a nursing home in Hanover, N.H. He was 84.

In addition to his career in education, he was a noted chemist and a scientific administrator who helped develop the atomic bomb during the World War II. He later served as U.S. High Commissioner to Germany and as the first U.S. ambassador to the Federal Republic of Germany.

Dr. Conant graduated from Harvard College in 1913 and earned a doctorate in chemistry from the university three years later. He served on the Harvard faculty as a professor of chemistry from 1919 to 1933, when he became president of the university, a post he held until 1953. He took leave for government service in 1940 and was one of the guiding forces in the massive scientific programs undertaken during the war. In addition to helping develop the atomic bomb, he played a role in the development of radar, synthetic rubber and new explosives.

After resigning the presidency of Harvard, he became High Commissioner and then Ambassador to Germany. He returned to the United States in 1957 and then began a series of studies on secondary education in the United States that have been credited with creating the American high school as it exists today.

These studies took up where a committee of Harvard faculty members appointed by Dr. Conant during the war years had left off. The Harvard report, published in 1945, was called "General Education in a Free Society." It argued that American colleges and universities must provide students with a broad general knowledge of the arts and sciences as well as specialized training in the fields of their choice.

This study became the blueprint for college curricula throughout the country and required "general education" courses became their hallmark. They remained a part of the required curricula until the period of student protest that accompanied the Vietnam war.

Although "General Education in a Free Society" was addressed specifically to the question of what colleges ought to be teaching, more than half of it was a study of American high schools - the source of the country's college students.

At that time, the nation's high school tended to reflect the recommendations made by the National Education Association in 1917. The NEA report noted that the industrialization of the American economy was proceeding apace, that many students were the sons and daughters of immigrants or were themselves new arrivals in the country, and that America had only recently emerged as a world power. Thus, high schools should prepare students by providing job skills and a knowledge of the American political system, among other goals.

The Harvard report of 1945 found that the education being offered in high schools no longer corresponded with the needs of American society. It raised the question of how high school could train the very bright student who might become a professional and at the same time teach youngsters how to work with each other in keping with the tsnets of the American democratic system.

This is the problem that Dr. Conant sought to solve in the work he did under grant from the Carnegie Foundation following his service as ambassador to Germany.His answer was the "comprehensive" high school, which would provide both academic and vocational programs.

To bring academic and vocational students together, he advocated the establishment of "home rooms," which would serve as micrcosms of the diversity to be found in the nation as a whole: students would learn to work together even though their high school programs had put them on different "tracks." This sense of working together would be enhanced, Dr. Conant argued, by students of all kinds studying the workings of the American government together. It would also be enhanced by participation in student government and extracurricular activities.

On the academic side, Dr. Conant recommended increased emphasis on the teaching of languages, sciences and mathematicss. These recommendations were embodied in the National Defense Education Act of 1959, the first legislation that provided substantial U.S. funds for local school systems.

Dr. Conant's proposals were first published in "The American High School Today," which appeared in 1959. This was a period in which many Americans were concerned that the United States might be lagging behind the Soviet Union in scientific development - notably, the space race - and that the country's educational system was at fault.

Dr. Conant himself noted this in his autobiography, "My Several Lives, Memoirs of a Social Inventor."

The timing was perfect," he wrote. "A wave of public criticism of the high schools, which had started after Sputnik (the first Soviet satellite), had reached its crest. School board members all over the country were anxious for specific answers."

The result was the closing of many existing high schools and the establishment in their place of "comprehensive" schools along the lines Dr. Conant had recommended.

According to Dr. Martin Kaplan, the executive assistant to the U.S. Commissioner of Education and a historian of education, the results are to be found in school systems all over the country.

"It is fair to say that Conant had dramatically revised the principles of 1917 and reinvented them for Cold War,Sputnik America," Kaplan said." The problem, of course, is that America has changed again dramatically since the Conant high school was invented. What we need to do is ask the same questions: who we are, who we want in society, where we're going in the future. But Conant never would have said that we should stick with his design foreever."

Dr. Conant was born in the Dorchester section of Boston. He graduated from the Roxbury Latin School in a Boston suburb before entering Harvard. It was at Roxbury Latin, according to Dr. Francis Keppel, a former harvard dean and U.S. commissioner of education, that the first developed an interest in science and history.

"He took the rational man's view of historical readings," Keppel said. "He was very much influenced by Jefferson, the Constitution and the Declaration of Independence. He felt strongly about the mixing of social classes. I'd call him an old-fashioned radical."

Thus, while believing deeply in egalitarianism, Dr. Conant advocated the establishment of junior colleges with federal funds at the same time that he was arguing that American scientists must learn foreign languages the better to compete with Communism. But the problem of reconciling the interests of the high school or community college graduate - not to mention those of the high school dropout - with those of the more highly trained professional remains.

It was in an effort to reserve this that Dr. Conant established the Harvard national scholarships during his tenure as president of the university. They were designed to make the school available to students on the basis of merit and financial need. Another innovation he made at Harvard was the establishment of the Niemann Fellowships, which allow journalists to spend a year at the university.

Dr. Conant and his wife, the former Grace Thayer Richards, who survives him, had maintained homes in New York City and Hanover, N.H., in recent years. Other survivors include two sons.