sth confused me

[eluser]vantao[/eluser]
I am a newbie to codeigniter!however, something about CI_URI confused me,let's describe it:

Code:

class CI_URI {

    var    $keyval    = array();
    var $uri_string;
    var $segments        = array();
    var $rsegments        = array();

    /**
     * Constructor
     *
     * Simply globalizes the $RTR object.  The front
     * loads the Router class early on so it's not available
     * normally as other classes are.
     *
     * @access    public
     */
    function CI_URI()
    {
        $this->config =& load_class('Config');
        log_message('debug', "URI Class Initialized");
    }
        }

it's a summary of CI_URI,only include constructor method.
what screwed me is this statement:

$this->config =& load_class('Config');

as above there has no member $config in class CI_URI,why this statement use it??????