void Start()
{
endCollider = end.GetComponent <Collider2D> ();
fox = Instantiate <Fox> (foxPrefab, start.offScreenTransform.position, Quaternion.identity);
foxCollider = fox.GetComponent <Collider2D> ();
Dog[] dogArray = FindObjectsOfType <Dog> ();
dogs = new List <Dog> (dogArray);
Invoke("ShowExit", startDelay);
}