You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query>
    <pages>
      <page pageid="193" ns="0" title="Börner, Otto Alexander" />
      <page pageid="452" ns="0" title="Von Kausler, Heinrich Eduard" />
      <page pageid="552" ns="0" title="(Noyer-)Weidner, Alfred Alexander Friedrich" />
      <page pageid="914" ns="0" title="Brink, Bernhard Aegidius Konrad (auch: Barend bzw. Bernard) ten" />
      <page pageid="915" ns="0" title="Tannenberg, Alfred Wolfgang von Wurzbach Ritter von" />
      <page pageid="918" ns="0" title="Frankhauser, Franz" />
      <page pageid="919" ns="0" title="Horning, Adolf" />
      <page pageid="920" ns="0" title="Rindler, Rosita Schjerve" />
      <page pageid="921" ns="0" title="Wiese, Bertold Heinrich Friedrich" />
    </pages>
  </query>
</api>