网页滚动图片中间无间隔简单代码

要求图片滚动一圈之后中间无间隔，首尾相接，代码简单！！！！急~~~

向左滚动：
<div id=demo pic/1.jpg" width="156" height="200" /><img src="pic/2.jpg" width="160" height="198" /><img src="pic/3.jpg" width="155" height="200" /><img src="pic/4.jpg" width="157" height="200" /></td><td id=demo2 valign=top></td></tr></table></div>
<script>
var speed=30
demo2.innerHTML=demo1.innerHTML
function Marquee(){
if(demo2.offsetWidth-demo.scrollLeft<=0)
demo.scrollLeft-=demo1.offsetWidth
else{
demo.scrollLeft++
}
}
var MyMar=setInterval(Marquee,speed)
demo.onmouseover=function() {clearInterval(MyMar)}
demo.onmouseout=function() {MyMar=setInterval(Marquee,speed)}
</script>