function getEl(elID) {
 if (document.getElementById) {
  return document.getElementById(elID);
 }
}

function show(id) {
 area = getEl(id);
 area.className = "show";
}

function openexcerpt() {
 for (i=1; i<14; i++) {
  excerpt = getEl('excerpt'+i);
  select = getEl('chapter');
  selected = select.options[select.selectedIndex].value;
  if (('excerpt'+i)==selected) {
   excerpt.className = "show excerpt";
  } else {
   excerpt.className = "hidden excerpt";
  }
 }
}