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-continue>
    <allredirects garcontinue="CSV_cytologie|830" />
  </query-continue>
  <query>
    <pages>
      <page pageid="179" ns="0" title="C-reactive protein" />
      <page pageid="209" ns="0" title="HCO3" />
      <page pageid="230" ns="0" title="ß-globines" />
      <page pageid="431" ns="0" title="Bloedafname reptielen" />
      <page pageid="812" ns="0" title="Babesia al" />
      <page pageid="814" ns="0" title="Beta globuline" />
      <page pageid="815" ns="0" title="Bloedname micro-collectie" />
      <page pageid="816" ns="0" title="Brucella canis al" />
      <page pageid="863" ns="0" title="Kaliumbromide" />
      <page pageid="2246" ns="0" title="Babesia (hond)" />
    </pages>
  </query>
</api>