WEST BERLIN, JULY 20 -- For the first time on their remarkably smooth path to unification, the two Germanys have come to a wall they cannot breach -- abortion.

After months of negotiations over their opposing abortion laws, East and West Germany have agreed to disagree. When the two countries become one, as they are scheduled to do in December, abortions will remain legal in the eastern part of the country and largely illegal in the western part.

But only women who live in what is now East Germany will be allowed to have abortions there. Women who now live, for example, in West Berlin can and do travel to East Berlin to have a legal abortion. But after December, West German women who seek abortions at East German hospitals will be prosecuted to prevent "abortion tourism from West to East," according to Juergen Schmid, a Bonn Justice Ministry spokesman.

As the two societies merge, West Germany's laws and customs have taken precedence over East German ways in almost every case, leading many East Germans to feel that their country has been swallowed whole.

Abortion is the most powerful issue still separating the two countries. But there are others, ranging from smoking rules to shopping hours.

East Germans are accustomed to separate facilities in restaurants and public transportation for smokers and non-smokers. Many such restrictions are illegal in West Germany, where courts have ruled that non-smoking sections in restaurants discriminate against the rights of smokers.

West Germany requires all stores to close weekday evenings, Saturday afternoons and all day Sunday. East Germany allows stores to open when they choose.

West Germany has no speed limit on its highways; in response to West Germans' demands, East Germany has already pushed its limit up from 60 mph to 80 mph.

Safety and environmental groups in the West are pushing to use unification as an opportunity to limit West Germans' cherished freedom to fly down the autobahns at 160 mph or more. But driving associations and transportation officials agree that the drivers' lobby is almost impossible to defeat. No speed limit is likely.

"Not everything in this society was stupid and useless," said Alfonse Wonneberg, an East Berlin educator. "For example, you can make a right turn on a red light here, but not in the West. It makes sense for traffic and the environment, but now we will lose it simply because it's not how they do things in the West. I call it a national chutzpah."

The abortion solution reached in the ongoing unification talks between the two Germanys is only temporary. The Justice Ministry said that the all-German parliament to be elected in December will move "as quickly as possible" to devise one rule for the entire country.

In East Germany, abortions are legal and free on demand through the 12th week of pregnancy. In West Germany, abortion is illegal unless a panel of physicians agrees that it is necessary because of the pregnant woman's physical or emotional health.

The agreement was immediately denounced by advocacy groups in both countries, which promised to continue their efforts to extend each Germany's law to the rest of the unified state.

Theo Weigel, chairman of the conservative Christian Social Union, a member of West Germany's ruling coalition, said his party will "use every bit of political influence" it can muster to extend the West's abortion restrictions to all of Germany.

But the opposition West German Social Democratic Party said it would seek to stop prosecution of West German women who want to travel east for an abortion.