if (document.images) {
  var first_off = new Image();
  first_off.src = "img/Slice-02.jpg";
  var first_on = new Image();
  first_on.src = "img/Slice-02-over.jpg";

  var second_off = new Image();
  second_off.src = "img/Slice-03.jpg";
  var second_on = new Image();
  second_on.src = "img/Slice-03-over.jpg";

  var third_off = new Image();
  third_off.src = "img/Slice-04.jpg";
  var third_on = new Image();
  third_on.src = "img/Slice-04-over.jpg";

   var fourth_off = new Image();
  fourth_off.src = "img/Slice-05.jpg";
  var fourth_on = new Image();
  fourth_on.src = "img/Slice-05-over.jpg";

  var fifth_off = new Image();
  fifth_off.src = "img/Slice-06.jpg";
  var fifth_on = new Image();
  fifth_on.src = "img/Slice-06-over.jpg";


}

function activate(imgName) {
  if (document.images) {
    if ( eval(imgName + "_on.complete") ) {
      document.images[imgName].src = eval(imgName + "_on.src");
    }
  }
}

function deactivate(imgName) {
  if (document.images) {
    if ( eval(imgName + "_off.complete") ) {
      document.images[imgName].src = eval(imgName + "_off.src");
    }
  }
}