If there's an object whose id = "svg1" && type = "image/svg+xml" in html, jQuery can be used like this to access its elements:

<object id="svg1" data="123.svg" type="image/svg+xml"></object>
var svg1 = document.getElementById("svg1").contentDocument;
$(svg1).find('#m > ellipse')
  .delay(500)
  .queue(function()
  { 
    $(this).attr('fill', '#ff0000'); 
    $(this).attr('stroke', '#ff0000'); 
    $(this).dequeue();
  })
  .delay(5000)
  .queue(function()
  { 
    $(this).attr('fill', '#0000ff'); 
    $(this).attr('stroke', '#0000ff'); 
    $(this).dequeue();
  })

    First get the DOM of the svg file. '#m > ellipse' means id = m and find its children tag <ellipse>. Delay 0.5s, then change some of its attributes, then delay 5s, then change attributes. Remeber to use .queue and dequeue().