Tobacco stands in dozens of U.S. cities last week sported cigarette brands that few U.S. smokers had ever seen. To the amazement of many a dealer, packages of the new brands were snapped up by intense young men with briefcases and suspiciously bulging pockets. Who were the young men? They were agents for U.S. cigarette companies, anxiously collecting their competitors' new smokes to rush them back to the laboratory for analysis. Undeterred by the cancer reports—cigarette sales are running 5% ahead of 1958—U.S. cigarette companies have taken off on a scramble to grab a bigger share of the $4¼...