     // Returns an entity in this scene that matches the given ID
     func getEntityByID(id: Int) -> GPEntity?
     {
-        for entity in entities
+        for entity in _entities
         {
             if(entity.id == id)
             {

    {
        system.willRemoveFromScene();
    
        self.systems -= system;
    
        // Remove the system as a notifier
        self.notifiers -= system;
    
        system.didRemoveFromScene();
    }
    // Returns a system in this game scene that derives from a specific class
    func getSystemWithType(systemClass: AnyClass) -> GPSystem?
    {
        for system in systems
        {
            if(system.isKindOfClass(systemClass))
            {

    // Removes an entity from this scene
    func removeEntity(entity: GPEntity)
    {
        self._entities.remove(entity);
    
        entity.node.removeFromParent();
    
