WASHINGTON (AP) _ Publish or perish has always been the merciless law of the academic jungle. A young professor must produce one _ or sometimes two _ books within seven years to get tenure, with its lifetime guarantee of employment. Without tenure, it is time to find another job.

But the rules are changing, with the double-edged consequences of the guillotine. University libraries, under tight budgets, have been buying fewer academic books from the nation's university presses.

With fewer orders from their main customers, the university-run publishing houses have started rejecting scholarly books out of marketplace considerations _ not whether they will advance the state of human knowledge, but whether they will sell.

Young scholars, however, have nowhere other than the nation's approximately 100 university presses to publish their works, which frequently are reworked doctoral dissertations.

James Shapiro, a professor of English and comparative literature at Columbia University, said young professors already are feeling the guillotine's edge. He told of one untenured teacher whose book on literary theory was rejected by a university press on the ground it was ``too theoretically sophisticated.'' That, he suspects, was ``the polite way of saying that, given current market conditions, the monograph will never sell.''

Only a university press would publish a book on ``Early Chinese Medical Literature'' or ``Towards a Postmodern Theory of Narrative'' _ two titles in the latest Columbia University Press catalog.

The problem has reached such proportions that the academics did what they do in crisis: They convened a conference here last week to explore ``The Specialized Scholarly Monograph in Crisis.'' About 150 university librarians, press executives and professors attended.

``The situation does not bode well for the long-term health of education and scholarship in the humanities and the social sciences,'' said Mary M. Case, director of the Office of Scholarly Communication of the Association of Research Libraries, one of three sponsoring organizations.

``If scholars in low-sales fields cannot get published and tenured, there may come a time when there are no faculty to teach in these fields,'' she said.

``Their lives are on the line if they are in fields where they can't publish,'' added Sanford Thatcher, who runs the Pennsylvania State University Press. ``And the lifeblood of scholarship is nourished by these books.''

Stephen Humphreys, a professor of history at the University of California, Santa Barbara, delivered a speech on ``Why Do We Write Stuff That Even Our Colleagues Don't Want to Read?''

His answer: A book, more visible than a mere journal article, is reviewed by scholarly journals and is more likely to become the focus of serious debate. ``It is an opportunity to spread one's wings and try to do something `major.'''

The conference explored whether monographs _ books of specialized academic research on narrow topics intended to be read by other specialists _ could be published on the Internet, and who would foot the bill.

Columbia, Johns Hopkins, Massachusetts Institute of Technology, Stanford, Yale and the Universities of California and Michigan are among schools experimenting with or considering computer sites for ``electronic monographs.'' Columbia hopes enough institutions will agree to pay fees ranging from $595 to $1,195 a year to cover costs.

Big sales are rarely within reach of university presses. While some commercial publishing houses have decided not to bring out books expected to sell fewer than 10,000 copies, university presses often sell fewer than 500.

But now, a book that would sell 500 copies to university libraries a decade ago now may be lucky to be ordered by 200.

Penn State's Thatcher said much of the problem lies in the escalating costs of scholarly journals, especially scientific journals. Robert Wedgeworth, librarian at the University of Illinois, said a journal can cost $2,000 for a year's subscription and still attract no more than one or two readers.

That eats away libraries' book budgets. ``But basically the political power on campus resides with the scientists, not the humanists,'' Thatcher said.

Columbia's Shapiro insisted that universities with endowments in the millions or even billions of dollars should be willing to subsidize both university presses and libraries.

But he is pessimistic that anything like that is likely because society does not value scholarship as it once did. ``What you get is a very gradual dumbing down of a culture,'' he said. ``And people are not really uncomfortable with that.''