A row with uncomfortable echoes of the past is gripping the world of Germany's student duelling societies after a club admitted a non-European member.
Duellers in Munich objected to the fact a Mannheim club had allowed a member with an Asian background to join, despite his service in the German army.
Mannheim members stood by their decision, and called for a more liberal direction for the clubs.
The clubs' national association insisted they were not racist.
Stefan Dobner, its spokesman, said it was wrong to say the row was over an "Aryan" condition of membership for duelling societies.
The fraternities condemned racism, he said.
Under Hitler, Germany enacted race laws which stressed the superiority of the "Aryan race", as northern Europeans were defined by the Nazis.
About 1,300 Germans are active members of the 100 or so student duelling societies, or Burschenschaften, which also count some 10,000 past members.
Swords and scars
The current argument is over whether people with immigrant backgrounds can be true Germans, and part of what some see as a quintessentially German institution, the BBC's Stephen Evans reports from Berlin.
The row has thrown into disarray an arcane and secretive world of fraternities forged through duelling, he says.
Such societies are usually male and involve dressing up in traditional 19th Century outfits, as well as drinking and fighting with swords.
Real swords are used and the men who join often sport a scar on their cheeks to show they have fought a real duel.
The Mannheim issue was to be debated at the annual meeting of the societies to be held in the town of Eisenach this weekend.
There was a feeling from the more conservative elements in Bavaria that, according to internal documents, members with "non-European facial and bodily characteristics" did not qualify as Germans and so could not join what the objectors see as a bastion of true German identity, our correspondent says.
"Especially in times of rising immigration, it is not acceptable that people who are not from the German family tree should be admitted to the Burschenschaften," as one document puts it.
The threatened club responded with a statement on its website signed by its spokesman, Kai-Ming Au.
It said that the club would fight strongly against the attempt to expel it from the national association and would push for reform at national level.
A spokesman for the umbrella organisation of the fraternities in Germany said there had been long discussions and it had been decided not to expel the Mannheim club, though there would be further discussions.
The difficulty for the associations is that Germany has changed, our correspondent adds.
Citizenship used to be based on "blood lines" - in other words, immigrants were excluded - and the duelling clubs mirrored that idea.