Read the details from "The Workers of Ellis Island" and think about the central idea they support.Because he was only allowed to admit persons who were "clearly and beyond a doubt entitled to enter the United States," he had to be absolutely certain the person he was examining was not a member of one of the classes of persons barred from entering the country . . . .Ellis Island doctors were particularly watching for signs of contagious diseases. Incurable diseases included trachoma and tuberculosis and guaranteed a return trip to where the immigrant came from.