TORONTO, JUNE 23 -- Prime Minister Brian Mulroney urged Canadians today to "mend the divisions and heal the wounds" in the wake of a divisive defeat of constitutional amendments that were intended to unite the country and keep the predominantly French-speaking province of Quebec from seeking independence.

In a somber, nationally broadcast address that appeared to be directed as much to foreign money markets as to his own constituency, Mulroney said he was "dismayed that Quebec will not be able, at this time, to join the constitutional family with honor and dignity."

When Canada's constitution was drawn up in 1982, Quebec, then governed by the separatist Parti Quebecois, refused to sign. The constitutional amendments, which would have transferred some powers from the central government to the provinces and would have given Quebec special status as a "distinct society," were aimed in part at getting Quebec to sign the constitution.

The amendments, known as the Meech Lake accord, were approved by leaders of the 10 provinces at a conference at Quebec's Meech Lake in 1987. But they were nullified today after Newfoundland and Manitoba failed to ratify them before the three-year deadline expired.

Although Mulroney vowed to continue to work toward bringing Quebec under the constitution, Quebec Premier Robert Bourassa told a news conference in Quebec City that he would no longer participate in constitutional negotiations.

Bourassa, in measured and restrained remarks, made it clear that he is still, for now, a committed federalist, but is keeping his options open. He said he would negotiate with the central government on such issues as Quebec gaining more control over immigration policy so that the province can preserve its French character.

When asked about the possibility of the province seeking sovereignty, Bourassa avoided making precipitous threats, cautiously responding, "Quebec has a freedom of choice and is going to make its choice in realism and calm."

During the news conference, he repeatedly mentioned that Quebec has "assets" and its own economic base, saying at one point, "In important decisions on the future, the economic dimension is very important."

Bourassa said his governing Liberal Party will examine all options available to the province, adding, "It is something that involves the very future of Quebec. I can't prejudge the discussions."

Mulroney said that the failure of the provincial legislatures of Newfoundland and Manitoba to ratify the constitutional reforms by today's deadline holds "potentially significant implications" for Canada. But he urged the outside world to view political events here in perspective and remember that "Canada always overcomes challenges to its unity."

Mulroney appeared to be anticipating investor reaction to the constitutional crisis when markets reopen Monday. Economists have said that perceptions of political instability in Canada and fears that Quebec may separate from the 123-year-old confederation could trigger a free fall in the Canadian dollar and prompt a flight of foreign capital in the bond market.

To many French Canadians, the Meech Lake accord represented nothing less than an acceptance of Quebec and its Frenchness by English Canada. Most Quebecers said they wanted to be part of Canada, but they also wanted to be recognized as a distinct part.

To many English-speaking Canadians, however, the amendments represented nothing more than an attempt by Quebec to grab powers that would be held by no other province and to diminish the power of the English-dominated central government.

In his broadcast address, Mulroney said the Meech Lake accord failed because it had become a "lightning rod for discontent" about a range of issues, including budgets and taxes, and had stimulated regional rivalries and tensions between English- and French-speaking Canadians.

He said he was deeply disappointed that after three years of frequently acrimonious debate, two provinces, representing 6 percent of Canada's 26 million population, had thwarted constitutional reform.

"Despite all of this effort, we have missed an opportunity to turn a page and open a new chapter in our constitutional history," the prime minister said. He suggested that the country needs at least a brief moratorium in its debate over its national identity, adding, "There is much to reflect upon before we try to amend the constitution" again.

Mulroney, who was twice elected on his promises to unite Canada in spite of its powerful centrifugal forces of regionalism and cultural and linguistic differences, came under scathing criticism by opposition leaders because of his handling of the Meech Lake reforms.

In an equal-time broadcast, Herb Gray, parliamentary leader of the opposition Liberal Party, accused Mulroney of deliberately delaying compromise negotiations leading up to the ratification process in order to create a crisis atmosphere in which Newfoundland and Manitoba would have to approve the accord or be blamed for the breakup of Canada.

Recalling that Mulroney said in an interview with Toronto's Globe and Mail newspaper that he had timed the negotiations in order to force the provincial premiers to "roll the dice," Gray said, "I believe most Canadians now seriously question the prime minister's moral authority to govern."

The Meech Lake accord's defeat represented a bitter political failure for Mulroney, whose public approval rating in recent polls had already dropped to 16 percent.