XmlDocument - load from string?

protected void Page_Load(object sender, EventArgs e)
{
XmlDocument doc = new XmlDocument();
try
{
string path = Server.MapPath(".");
doc.Load(path+"whatever.xml");
}
catch (Exception ex)
{
lblError.Text = ex.ToString();
return;
}


// Convert XML to a JSON string
string JSON = XmlToJSON(doc);


// Replace \ with \\ because string is being decoded twice
JSON = JSON.Replace(@"\", @"\\");


// Insert code to process JSON at end of page
ClientScriptManager cs = Page.ClientScript;
cs.RegisterStartupScript(GetType(), "SpaceJSON", "space_processJSON('" + JSON + "');", true);
}

Instead if of loading the xml from a file, how do I load it from a string?