Call and storing a plugin from a variable or string

Call and storing a plugin from a variable or string

I need to store a plugin as a variable or a string to be called later.  I feel like I am missing something really simple.

here is a sample test I was trying.
  1. $.fn.echo = function (s) {
                $(this).each(function () {
                    $(this).html(s);
                });
                return this;
     };

     $.fn.callMethod = function (m, v) {
                $(this).each(function () {
                    $(this).m(v);
                });
                return this;
     };

    $(document).ready(function () {
                $('body').append($('<div/>').echo('hello'));
                $('body').append($('<div/>').callMethod(echo,'calling echo'));
     });
I receive the error "echo is not defined".  Any Ideas?  Is there a built in way to do this?