calling super in initialize

class Person    
    def initialize(name)
        @name = name
    end    
end

class Employee < Person
end

emp = Employee.new # throws error wrong number of arguments

emp = Employee.new("foo") # parent class initialize method is called

class Employee < Person
    def initialize(name, designation)
        super(name)
        @designation = designation
    end
end

emp = Employee.new("foo", "bar")