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>
    <images gimcontinue="1|Chemical_structure.jpg" />
  </query-continue>
  <query>
    <pages>
      <page pageid="33442" ns="6" title="File:Actual brain.jpg" contentmodel="wikitext" pagelanguage="en" touched="2011-12-24T17:29:40Z" lastrevid="46355" counter="2659" length="0" new="" />
      <page pageid="33570" ns="6" title="File:Analogies example.jpg" contentmodel="wikitext" pagelanguage="en" touched="2011-12-24T17:29:40Z" lastrevid="46544" counter="2845" length="0" new="" />
      <page pageid="33446" ns="6" title="File:Arguments sun faces.jpg" contentmodel="wikitext" pagelanguage="en" touched="2011-12-24T17:29:40Z" lastrevid="46359" counter="2623" length="0" new="" />
      <page pageid="12782" ns="6" title="File:Awarepath multiextension 1.jpg" contentmodel="wikitext" pagelanguage="en" touched="2012-02-16T06:18:52Z" lastrevid="23179" counter="2641" length="0" new="" />
      <page pageid="33437" ns="6" title="File:Blue butterfly.jpg" contentmodel="wikitext" pagelanguage="en" touched="2011-12-24T17:29:40Z" lastrevid="46345" counter="2664" length="0" new="" />
      <page pageid="33577" ns="6" title="File:Book worm.jpg" contentmodel="wikitext" pagelanguage="en" touched="2011-12-24T17:29:40Z" lastrevid="46551" counter="2296" length="0" new="" />
      <page pageid="12703" ns="6" title="File:BrainImage.jpg" contentmodel="wikitext" pagelanguage="en" touched="2011-12-24T17:29:40Z" lastrevid="22639" counter="2504" length="0" new="" />
      <page pageid="33458" ns="6" title="File:Brain circuits.jpg" contentmodel="wikitext" pagelanguage="en" touched="2011-12-24T17:29:40Z" lastrevid="46379" counter="2854" length="0" new="" />
      <page pageid="33443" ns="6" title="File:Brain magnifying glass.jpg" contentmodel="wikitext" pagelanguage="en" touched="2011-12-24T17:29:40Z" lastrevid="46356" counter="2918" length="0" new="" />
      <page pageid="33427" ns="6" title="File:Chem-lab saal uni-leipzig brockhaus.jpg" contentmodel="wikitext" pagelanguage="en" touched="2011-12-24T17:29:40Z" lastrevid="46302" counter="2689" length="0" new="" />
    </pages>
  </query>
</api>