if (document.images) { 

var img10on = new Image();
img10on.src = "../images/cat_nature02.gif"; 
var img10off = new Image();
img10off.src = "../images/cat_nature01.gif";

var img11on = new Image();
img11on.src = "../images/cat_geography02.gif"; 
var img11off = new Image();
img11off.src = "../images/cat_geography01.gif";

var img12on = new Image();
img12on.src = "../images/cat_plant02.gif";
var img12off = new Image();
img12off.src = "../images/cat_plant01.gif";

var img13on = new Image();
img13on.src = "../images/cat_animal02.gif";
var img13off = new Image();
img13off.src = "../images/cat_animal01.gif";

var img14on = new Image();
img14on.src = "../images/cat_insect02.gif";
var img14off = new Image();
img14off.src = "../images/cat_insect01.gif";

var img15on = new Image();
img15on.src = "../images/cat_fish02.gif";
var img15off = new Image();
img15off.src = "../images/cat_fish01.gif";

var img16on = new Image();
img16on.src = "../images/cat_bird02.gif";
var img16off = new Image();
img16off.src = "../images/cat_bird01.gif";

var img17on = new Image();
img17on.src = "../images/cat_human02.gif";
var img17off = new Image();
img17off.src = "../images/cat_human01.gif";

var img18on = new Image();
img18on.src = "../images/cat_fiction02.gif";
var img18off = new Image();
img18off.src = "../images/cat_fiction01.gif";

var img19on = new Image();
img19on.src = "../images/cat_tool02.gif";
var img19off = new Image();
img19off.src = "../images/cat_tool01.gif";

var img20on = new Image();
img20on.src = "../images/cat_vehicle02.gif"; 
var img20off = new Image();
img20off.src = "../images/cat_vehicle01.gif";

var img21on = new Image();
img21on.src = "../images/cat_letter02.gif"; 
var img21off = new Image();
img21off.src = "../images/cat_letter01.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'); 
} 

}