Four of the nation's top companies got new presidents last week. All worked their way up from the bottom. The new top men:
MONSANTO CHEMICAL: Charles Allen Thomas, 51, is a chemist turned manager. A Kentuckian, he went from M.I.T.
to General Motors' research department in 1923, helped develop ethyl gasoline.
He was running his own research laboratory when Monsanto bought it in 1936, took him along as research boss. During World War II he bossed the purification of plutonium, from 1945 to 1948 ran the Oak Ridge project, is now a Government adviser on top-secret scientific matters. For Monsanto, seventh biggest U.S.