private List<Texture> LoadTextures (String prefix, int numTextures)
    {
        List<Texture> textures = new List<Texture> ();
        for (var i = 0; i < numTextures; i++ )
        {
            var www = new WWW(prefix + i);
            yield www;
            textures.Add(www.texture);
        }
        return textures;
    }