pic1on = new Image( );
       pic1on.src = "images/home_roll.gif";
       pic1off = new Image( );
       pic1off.src = "images/home.gif";
       pic2on = new Image( );
       pic2on.src = "images/intro_roll.gif";
       pic2off = new Image( );
       pic2off.src = "images/intro.gif";
       pic3on = new Image( );
       pic3on.src = "images/react_roll.gif";
       pic3off = new Image( );
       pic3off.src = "images/react.gif";
       pic4on = new Image( );
       pic4on.src = "images/contribute_roll.gif";
       pic4off = new Image( );
       pic4off.src = "images/contribute.gif";
       pic5on = new Image( );
       pic5on.src = "images/about_roll.gif";
       pic5off = new Image( );
       pic5off.src = "images/about.gif";
       
  function img_act (imgName)   {
      imgOn = eval (imgName + "on.src");
      document [imgName].src = imgOn;
      }

  function img_inact (imgName)   {
      imgOff = eval (imgName + "off.src");
      document [imgName].src = imgOff;
      }