运行这段javascript为什么显示link1没有定义？

<html><head>
<title>test</title>
<script type="text/javascript">
function link1Over(){
link1.style.color = "red";
link1.style.fontSize = 36;
}
function link1Out(){
link1.style.color = "black";
link1.style.fontSize = 16;
}
</script>
</head><body>
<a href="#" name="link1" onMouseOver = "link1Over()" onMouseOut = "link1Out()">这是一个链接</a>
</body></html>