var image_index = 0;
image_list = new Array();
image_list[image_index++] = new imageItem("/n/naturalis/graphics/blad.gif");
image_list[image_index++] = new imageItem("/n/naturalis/graphics/kikker.gif");
image_list[image_index++] = new imageItem("/n/naturalis/graphics/paddestoel.gif");
image_list[image_index++] = new imageItem("/n/naturalis/graphics/papegaai.gif");
image_list[image_index++] = new imageItem("/n/naturalis/graphics/schelp.gif");
image_list[image_index++] = new imageItem("/n/naturalis/graphics/steen.gif");
image_list[image_index++] = new imageItem("/n/naturalis/graphics/vlinder.gif");
image_list[image_index++] = new imageItem("/n/naturalis/graphics/zebra.gif");
var number_of_image = image_list.length;

function imageItem(image_location) {
  this.image_item = new Image();
  this.image_item.src = image_location;
}

function get_ImageItemLocation(imageObj) {
  return(imageObj.image_item.src)
}

function getNextImage() {
  var time = new Date();
  var randomnumber = time & (number_of_image - 1);
  //var randomnumber = Math.floor(Math.random() * (number_of_image - 1));
  var new_image = get_ImageItemLocation(image_list[randomnumber]);
  return(new_image);
}

function randomImage(place) {
  var new_image = getNextImage();
  document[place].src = new_image;
}