jQuery Draggable Error: Object doesn't support this property or method

<html>
<head>

    <script src="jquery.js"></script>

    <script>
        $(document).ready(function() {
            jQuery(".dragthis").draggable();
            jQuery(".drophere").droppable();

        });
    </script>

    <style>
        .dragthis
        {
        }
        .drophere
        {
        }
    </style>
</head>
<body>
    <div class="dragthis">
        dragthis</div>
    <div class="drophere">
        drophere</div>
</body>
</html>