OOP Koncept with PHP 0.1alpha

<?php
abstract class Tier
{
    protected $Name;
    protected $Laut;
    public function gibNameAus()
    {
        echo $this->Name;
    }
    public function fibLaut()
    {
        echo $this->Laut;
    }
}

class Hund extends Tier {
    public function __construct()
    {
        $this->Laut = "Wuff";
        $this->Name = "Bello/HUND";
        $this->gibNameAus();
        echo "\n";
        $this->fibLaut();
    }
}
$obj = new Hund;
?>