if (document.images) {

   biography_off = new Image();
   biography_off.src = "images/biography_off.gif";
   biography_on = new Image();
   biography_on.src = "images/biography_on.gif";  
   
   contact_off = new Image();
   contact_off.src = "images/contact_off.gif";
   contact_on = new Image();
   contact_on.src = "images/contact_on.gif";

   events_off = new Image();
   events_off.src = "images/events_off.gif";
   events_on = new Image();
   events_on.src = "images/events_on.gif";
   
   illustration_off = new Image();
   illustration_off.src = "images/illustration_off.gif";
   illustration_on = new Image();
   illustration_on.src = "images/illustration_on.gif";

   galleries_off = new Image();
   galleries_off.src = "images/galleries_off.gif";
   galleries_on = new Image();
   galleries_on.src = "images/galleries_on.gif";

   home_off = new Image();
   home_off.src = "images/home_off.gif";
   home_on = new Image();
   home_on.src = "images/home_on.gif";
      
      
}

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

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