if (document.images) { 

var img1on = new Image();
img1on.src = "http://www.cmwalker.co.jp/img/menu01-on.gif"; 
var img1off = new Image();
img1off.src = "http://www.cmwalker.co.jp/img/menu01-off.gif"; 
var img2on = new Image();
img2on.src = "http://www.cmwalker.co.jp/img/menu02-on.gif";
var img2off = new Image();
img2off.src = "http://www.cmwalker.co.jp/img/menu02-off.gif";
var img3on = new Image();
img3on.src = "http://www.cmwalker.co.jp/img/menu03-on.gif"; 
var img3off = new Image();
img3off.src = "http://www.cmwalker.co.jp/img/menu03-off.gif"; 
var img4on = new Image();
img4on.src = "http://www.cmwalker.co.jp/img/menu04-on.gif";
var img4off = new Image();
img4off.src = "http://www.cmwalker.co.jp/img/menu04-off.gif";
} 

function On(name) { 
if (document.images) { 
document.images[name].src = eval(name + 'on.src'); 
} 
} 

function Off(name) { 
if (document.images) { 
document.images[name].src = eval(name + 'off.src'); 
} 

}