class variables in codeigniter

[eluser]Unknown[/eluser]
Why do class variables get erased after loading a view? Is there anyway to prevent this?

Code:

class Test extends CI_Controller {

var $test;

function hello() {
          $this->test="test";
          $this->load->view('hello_view');
}

function world() {
          print_r($this->test);
        }