Critics of the rapid trend toward concentration of press ownership, such as Rep. Morris Udall (D-Ariz.), complain that America has entered a new era of "chain store news."

But some newspaper company executives say the biggest single problem facing their industry today is an inability to expand.Acquisitions are becoming more difficult to find and continued growth of revenues and profits may be threatened.

Particularly concerned about the future for growth are the relatively small number of publicly owned firms - companies who sell some of their stock to the general public.

The newspaper industry always has been secretive about its economics and privately held newspapers or chains still dominate the business. In the past decade, however, a number of companies have "gone public" and a few more firms are likely to take such action before the 1970s are over.

Today, there are 13 major public newspaper companies and the newspapers they publish account for about 23 per cent of all daily U.S. circulation plus 26 per cent of Sunday circulation. There are a handful of smaller public companies and some papers are owned by other public corporations - E. I. duPont deNemours and the Seaboard Coast Line railroad, for example.

A petroleum giant, Mobil Corp., has expressed an interest in acquiring newspapers and most industry analysts forecast a gradual increase in the number of newspapers under control of public stock corporations.

By far the largest public company now in the business of publishing several newspapers is Times Mirror Co., of Los Angeles, ranked No. 232 on Fortune Magazine's list of the top 500 industrial firms in America.

Times Mirror annual revenues last year totaled $975.6 million, on which profits totaled $69.5 million. The company's 17,650 employees work in diversified lines of business - from forest products to book publishing and cable communications.

Otis Chandler, vice chairman of Times Mirror and publisher of the company's flagship. The Los Angeles Times, said he considers the overall firm to be "an information company, or a communications company."

Only about 40 per cent of annual revenues come from newspapers now owned - The Times (daily circulation of 1 million; Sundays, 1.28 million), Newsday on Long Island, N.Y. (daily, 467,000; Sundays, 439,000); Dallas Times Herald (daily, 221,000; Sundays, 325,000); and Orange Coast Daily Pilot, with six editions serving such communities as Newport Beach and Irvine (Daily, 46,000; Sundays, 46,000).

Although newspaper revenues have grown steadily during each year of the 1970s for the country's most profitable public publishing firm, revenues from newsprint and forest products operations last year soared to $263 million from $179 million in 1975.

Times Mirror produces plywood and hardboard and now owns 320,000 acres of Western timberland; two newsprint mills sell most of their product to The Times itself.

The company also owns professional and general book publishers, including the paperback New American Library; information services for the aeronautical and automotive industries; a variety of magazines including Popular Science, Golf and Sporting News, and television stations in Dallas-Ft. Worth and Austin.

With a management widely recognized as among the best in publishing and early adoption of new technologies (The Times plant is not unionized, which facilitated introduction of new equipment), Times Mirror started its drive for acquisitions and expansion in 1948, taking a lead among major publishers.

Today, however, Chandler is less than optimistic when he studies future acquisitions.

"We have not been able to make the acquisitions that we have tried to, over the past several years . . . we came close twice this year . . . but some of the other companies have bid prices up to such an extraordinary level that even though people may prefer to be associated with Times Mirror as, for example, Newsday was and Dallas was, they say in the end. 'We're sorry, fellows, but we've got to take a higher price because we have these shareholders' . . ." Chandler explained.

He was referring to two of the biggest newspaper acquisitions of this or any year - the takeover of Booth Newspapers (8 dailies in Michigan and Parade magazine; by the privately owned Newhouse Newspapers for $300 million in January, and the sale of the Kansas City Star and Times to the publicly owned Capital Cities Communications, for $125 million, in February.

In both instances, Times Mirror was interested - it was a spirited bidder for the Booth properties and "took a very hard pass" at Kansas City. Newhouse had picked up 25 per cent of Booth early in 1976 and when three Booth directors announced last October that they had pledged to sell their stock to Times Mirror for $40 a share, Newhouse counterattacked.

He offered $47 a share and Booth president James Sauter, who had led opposition to a Newhouse takeover, said: "It is clearly in the interest of Booth and stockholders to accept this offer." Thus was consumated the largest newspaper sale for cash in U.S. history.

"That's the major area of discouragement to our company, to the future of our company . . . where are we going to find acquisitions that are reasonable and are they all (all newspapers) going to be taken in the meantime by some of these other companies," Chandler continued.

What Chandler really is saying is that for remaining independent or family-owned newspapers today, it's a seller's market. The big companies want other papers to add to growth and the bidding obviously is ferocious for profitable newspapers in medium and small sized cities; purchasers must pay a lot more to buy the revenues and profits produced by the monopoly newspapers in most cities (in the case of Booth, Newhouse paid three times book value).

Given the substantial costs of converting remaining big newspapers to the new technology, estate-tax laws that encourage owners of privately held papers to sell out and the desire of public publishing firms to expand, however, it is unlikely that companies such as Times Mirror will not continue to add to their list of properties.

A few weak dailies, at the same time, will either be sold for relatively low prices or folded.

Of one thing, Chandler said he is certain: Newspapers are healthy and here to stay, in general, and are not products of a dying industry. Times Mirror executives have forecast another record year in 1977, aided by higher advertising and circulation revenues at the newspapers.

But Chandler said the economics of publishing dictate an orientation to advertising revenues, rather than a drive for mass circulation, such as espoused by New York Post publisher Rupert Murdoch in a recent speech to the American Newspaper Publishers Association.

Chandler called Murdoch's talk "a lecture to American publishers" and the Los Angeles Times executives took great exception to Murdoch's message - that the press was too dull and in danger of losing its position unless new readers are attracted. "Too often the tedium is the message," Murdoch said.

If major dailies were to embrace the kind of "populist journalism" sought by Murdoch, Chandler said, "we might get a few more readers because they might be curious to see what the paper looks like." But the papers also would be attracting people with less purchasing power and "we wouldn't be able to sell any advertising because the advertisers would not be interested in that kind of circulation."

If newspapers lost their advertising base, "we wouldn't be able to pay fellows like you, and we would find ourselves going down the drain. The economics of the American newspaper publishing is based on advertising . . . not a circulation base . . . and that's what Mr. Murdoch fails to realize," Chandler asserted. "I think he's going to find that out in New York City."

Chandler pointed out that since The Times publishes more advertising than any paper in the world (120 million lines in 1976), with an average of more than 100 pages a day, "we have an enormous news hole."

Probably the most extensive report on newspaper coverage recently published in the daily press appeared in Chandler's Los Angeles Times last month. Written by Times reporter David Shaw, the article began on Page 1 and was continued on more than half a dozen inside pages, the length of a major magazine piece.

Shaw studied the front pages of the Los Angeles Times, New York Times and Washington Post for every day during the first five months of this year. He also studied other newspapers and concluded there was "no monolith" in the American press, that papers seldom agreed on what constitutes front-page news.

Only 28 times during a 155-study period did the three big papers agree on the "lead" story - the most important of the day. And local stories were found to dominate the front pages of most U.S. newspapers.

He found that the Los Angeles paper published more outright feature stories on Page 1 and fewer investigative pieces, or exposes, that the Washington and New York dailies. The L.A. Times also published more front-page disaster stories, despite Chandler's felling that such stories may be given too much exposure.