window.addEvent( 'domready', function(){
    $$( '.mehr' ).each(function(item){
        var thisSlider = new Fx.Slide( item.getElement( '.collapse' ), { duration: 500 } );
        thisSlider.hide();
        item.getElement( '.divUmschalter' ).addEvent( 'click', function(){ thisSlider.toggle(); } );  
    } );
} );