text: FAQ: I need an old version of the ij.jar file. Where can I get it?
  Given that ImageJ is constantly evolving, sometimes an old plugin may only run with a previous version of ImageJ and not the newest. Where can one get those older ij.jar files?
  The previous versions of ImageJ (i.e. the jar files) are available at:
  Just copy the i.jar file in the ImageJ folder and restart the program.
  For the latest version see this FAQ.