Dear Rich, I think this should work. Tree.html is the html file for the applet, whose code is in TreeApplet.java. I hope there is no conflict with your older version of java. If there is, I suspect is might come from line 68, which sets the space bar to work for "Update". You can delete that line, with no major effect to the program. Otherwise, if it won't compile for you, let me know what the offending code is and I'll see what I can do. Thanks for putting it up on the web. I haven't heard anything from McMullen. I told him that you recommended he might like the program, so I am a bit surprised he doesn't say anything. Because I know it is cool. Maybe he doesn't like it if it isn't very mathematical? I haven't sent it to Gromov yet. I will soon. I checked the web about cellular automata. There is quite an industry out there, which I didn't know about. The ideas are neat, but the pictures are not as cool as mine. (At least what I have seen so far). Cheers, Steven