function writeCaption(index){

	var msg ;

	switch(index){
	case 1:
			msg = "Greetings from the ferns"; break;
	case 2:
	default:
			msg = "Greetings not from the ferns"; break;
			return;
	}
	document.write(msg);
}

var _index = 1;
MAX_IMAGE = 13;

function increment(next){
	if( next ){
		if( _index >= MAX_IMAGE )
			_index = 1;
		else
			_index++;
	}else{
		if( _index <= 1 )
			_index = MAX_IMAGE;
		else
			_index--;
	}
}

function photoBack(){
	increment(false) ;
	document.images.photo.src = "images/photos_" + _index + ".jpg";
}
function photoNext(){
	increment(true) ;
 //	alert("index = " + _index );
	document.images.photo.src = "images/photos_" + _index + ".jpg";
}

function photoSet(index){
	if(( index > MAX_IMAGE )||( index <= 0 ))
		return;
	_index = index ;
	document.images.photo.src = "images/photos_" + _index + ".jpg";
}