if (document.images)
   {
     image_photo1_off= new Image(73,31);
     image_photo1_off.src="/media/thumbs/chimps/photo_1.gif";  
     
     image_photo1= new Image(73,31);
     image_photo1.src="/media/thumbs/chimps/photo_1_on.gif";
     
     image_photo2_off= new Image(73,31);
     image_photo2_off.src="/media/thumbs/chimps/photo_2.gif";  
     
     image_photo2= new Image(73,31);
     image_photo2.src="/media/thumbs/chimps/photo_2_on.gif";
     
     image_photo3_off= new Image(73,31);
     image_photo3_off.src="/media/thumbs/chimps/photo_3.gif";  
     
     image_photo3= new Image(73,31);
     image_photo3.src="/media/thumbs/chimps/photo_3_on.gif";
     
     image_photo4_off= new Image(73,31);
     image_photo4_off.src="/media/thumbs/chimps/photo_4.gif";  
     
     image_photo4= new Image(73,31);
     image_photo4.src="/media/thumbs/chimps/photo_4_on.gif";
     
     image_photo5_off= new Image(73,31);
     image_photo5_off.src="/media/thumbs/chimps/photo_5.gif";  
     
     image_photo5= new Image(73,31);
     image_photo5.src="/media/thumbs/chimps/photo_5_on.gif";
     
     image_video_off= new Image(57,31);
     image_video_off.src="/media/thumbs/chimps/video.gif";  
     
     image_video= new Image(57,31);
     image_video.src="/media/thumbs/chimps/video_on.gif";
     
     image_bio_off= new Image(96,31);
     image_bio_off.src="/media/thumbs/chimps/biography.gif";  
     
     image_bio= new Image(96,31);
     image_bio.src="/media/thumbs/chimps/biography_on.gif"; 
     
     image_family_off= new Image(96,31);
     image_family_off.src="/media/thumbs/chimps/family_tree.gif";  
     
     image_family= new Image(96,31);
     image_family.src="/media/thumbs/chimps/family_tree_on.gif"; 
     
     image_other_off= new Image(167,31);
     image_other_off.src="/media/thumbs/chimps/other_chimpanzees.gif";  
     
     image_other= new Image(167,31);
     image_other.src="/media/thumbs/chimps/other_chimpanzees_on.gif"; 
     
   }

function change1(picName,imgName)
 {
   if (document.images)
    {
      imgOn=eval(imgName + ".src");
      document[picName].src= imgOn;
    }
 }