为什么会出现删除线?

我下载一个Xml文件，大约有六万条数据，我用php读取，echo出来，在第16710条时出现文本删除线，这是为什么?

$xml = simplexml_load_file('JACS.xml'); 
$num=0;
foreach($xml->PubmedArticle as $ArticleInfo) 
{ 
   $num++;
   echo $num;
   echo &#39;<br><br>&#39;;
   $PubTime=$ArticleInfo->MedlineCitation->Article->Journal->JournalIssue->PubDate; 
   echo &#39;PublicationDate:&#39;.$PubTime->Year.&#39; &#39;.$PubTime->Month.&#39; &#39;.$PubTime->Day.&#39;<br><br>&#39;;
   $JournalName=$ArticleInfo->MedlineCitation->Article->Journal->Title;
   echo &#39;JournalName:&#39;.$JournalName.&#39;<br><br>&#39;;
   $PubTitle=$ArticleInfo->MedlineCitation->Article->ArticleTitle;
   echo &#39;Title:&#39;.$PubTitle.&#39;<br><br>&#39;;
   $PubAbstract=$ArticleInfo->MedlineCitation->Article->Abstract->AbstractText;
   echo &#39;Abstract:&#39;.$PubAbstract.&#39;<br><br>&#39;;
   echo &#39;Author:&#39;;
   $Authorlist=$ArticleInfo->MedlineCitation->Article->AuthorList;
   foreach($Authorlist->Author as $publisher)
   {
       echo $publisher->ForeName.&#39; &#39;.$publisher->LastName.&#39;|&#39;;
   }
   echo &#39;<br><br>&#39;;
   $Affiliation=$ArticleInfo->MedlineCitation->Article->AuthorList->Author[0]->AffiliationInfo->Affiliation;
   echo &#39;Affiliation:&#39;.$Affiliation;
   echo &#39;<br><br><br><br>&#39;;
}