function changePhotoLarge(index)
{
   // photo.
   var src = document.getElementById('photoThumb' + index);
   var dest = document.getElementById('placeholder');
   dest.src = src.value;

   // caption.
   src = document.getElementById('photoThumbCaption' + index);
   dest = document.getElementById('photoLgCaption');
   Utils.removeChildren(dest);
   dest.appendChild(document.createTextNode(src.value));
} // changePhotoLarge