function nextImg() {
    new Effect.Morph('imgContainer',
    {
    style:"width:450px; height:338px",
    duration:1,
    beforeStart: function(o) {
        $('myImg').src = "bg.png";
    },
    afterFinish: function(o) {
        $('myImg').src = "IMG_3.jpg";
    }
    });
}