The National Hockey League governors, generally considered incapable of agreement on any subject, will begin debate on some perplexing matters today when the league's summer meetings open in Montreal.

First in import is the subject of merger with the reeling World Hockey Association. An NHL committee that has been exploring the subject with WHA owners will present its report on possible accommodation.

If that doesn't create sufficient dissension, there is the proposal for collective bargaining changes that was aired during meetings with the NHL Players Association in Bermuda last week. And, in what seems to be a revolving-door issue, there is the subject of a successor for Clarence Campbell, the league's 72-year-old president.

"I've worked this long (32 years), what the hell difference does it make if I go another year," said Campbell, which might table that item, since agreement on a replacement is lacking John Ziegler, the NHL board chairman, is the front-runner, but the governors met a month ago and declined to endorse him.

The other matters are more crucial. On the merger issue, the weaker clubs financially would like to welcome some WHA members, both to pocket an indemnity and to end the bidding war over players. The prosperous clubs prefer Campbell's position - let the beggars die a slow death.

Any accommodation with the WHA would require terms with the players, since merger would void the current labor agreement, which has three years to run. The price for merger, as set forth on varied occasions by Alan Eagleson, the Players' Association boss, would be either half the indemnity fee or the end to the league's Rozelle Rule - compensation for signing free agents.

Another point discussed with the players in Bermuda was a possible change to a football-type player control arrangement, with strict limits on rosters and all other players up for grabs. A corollary would be a waiver system in which players waived through the league could be dropped without further contractual obligation.

Although Campbell recently said that "when the chips are down, he (Eagleson) acts like one" in reference to a rhetorical comparison of Eagleson and the "Tooth Fairy," it seems unlikely that those long-term, no-cut contracts would be abrogated.

Some WHA owners have been quoted recently as expressing willingness to spend as much as $5.2 million apiece for entrance to the NHL. Such statements seem too absurd economically to be anything more than salve for fans clamoring for NHL competition.

A more potent obstacle to merger, however, is the two-thirds vote required for admission of new teams. Despite the lure of some easy money, such agreement from men accustomed to quibbling over much smaller issues is remote. Besides, it's a day-to-day matter of what constitutes two-thirds, with both the St. Louis and Cleveland situations still unresolved.