Span wrap

HTML

<p>"May you live all the days of your life." — Jonathan Swift</p>
<p>"Two May you live all the days of your life." — Jonathan Ford</p>
<p>"Three May you live all the days of your life." — Jonathan Xcel</p>

CSS

span {
  background-color: #000
}

JavaScript

$(document).ready(function() {
  $('p').each(function() {
    var orgText = $(this).html();
    var spanText = orgText.substring(0, (orgText.indexOf('"') - 1)) + '<span>' + orgText.substring(orgText.indexOf('"'), orgText.length) + '</span>';

    $(this).html(spanText);
  });
});