if (document.images) {

themis_logo_on = new Image();
themis_logo_on.src = "http://themis.asu.edu/images/subpage/themis_logo_on.jpg";
themis_logo_off = new Image();
themis_logo_off.src = "http://themis.asu.edu/images/subpage/themis_logo.jpg";


home_on = new Image();
home_on.src = "http://themis.asu.edu/images/subpage/home_on.jpg";
home_off = new Image();
home_off.src = "http://themis.asu.edu/images/subpage/home.jpg";


about_on = new Image();
about_on.src = "http://themis.asu.edu/images/subpage/about_on.jpg";
about_off = new Image();
about_off.src = "http://themis.asu.edu/images/subpage/about.jpg";


map_on = new Image();
map_on.src = "http://themis.asu.edu/images/subpage/map_on.jpg";
map_off = new Image();
map_off.src = "http://themis.asu.edu/images/subpage/map.jpg";


globalmap_on = new Image();
globalmap_on.src = "http://themis.asu.edu/images/subpage/globalmap_on";
globalmap_off = new Image();
globalmap_off.src = "http://themis.asu.edu/images/subpage/globalmap";


gallery_on = new Image();
gallery_on.src = "http://themis.asu.edu/images/subpage/gallery_on.jpg";
gallery_off = new Image();
gallery_off.src = "http://themis.asu.edu/images/subpage/gallery.jpg";


discoveries_on = new Image();
discoveries_on.src = "http://themis.asu.edu/images/subpage/discoveries_on.jpg";
discoveries_off = new Image();
discoveries_off.src = "http://themis.asu.edu/images/subpage/discoveries.jpg";

software_on = new Image();
software_on.src = "http://themis.asu.edu/images/subpage/software_on.jpg";
software_off = new Image();
software_off.src = "http://themis.asu.edu/images/subpage/software.jpg";

// Old button GIF
missions_on = new Image();
missions_on.src = "http://themis.asu.edu/images/subpage/missions_on.jpg";
missions_off = new Image();
missions_off.src = "http://themis.asu.edu/images/subpage/missions.jpg";

// New button GIF
project_on = new Image();
project_on.src = "http://themis.asu.edu/images/subpage/project_on.jpg";
project_off = new Image();
project_off.src = "http://themis.asu.edu/images/subpage/project.jpg";

asu_on = new Image();
asu_on.src = "http://themis.asu.edu/images/subpage/asu_on.jpg";
asu_off = new Image();
asu_off.src = "http://themis.asu.edu/images/subpage/asu.jpg";

}

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

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