Ehsan Jami sees himself as the legendary Dutch boy who used his finger to plug a leaking dike. Jami, a Dutch politician, is trying to prevent a flood of what he views as intolerant Muslim immigrants threatening to overrun the Netherlands and all of Europe. He’s not alone. In France, Germany and across Western Europe, a vigorous public debate is under way over preservation of national identities, the assimilation of minorities and tolerance of different cultures. Shelley Emling reports.