Dear David,
there is no umlaut in Buchner. I verified it with a German biochemistry
textbook. Note the difference to the German poet Georg Bu"chner with umlaut.
In the textbook, no reference to any brothers is made. I'll ask around and
let you know. As far as I know, Buchner worked in Berlin which would make it
easy for me to find it out.
Greetings
Stefan Schuster
