Reading the rags

The magazine cartoon is not yet an endangered species, but perhaps we should start keeping watch. In their heyday in the '30s and '40s, cartoons peppered our magazines. The Saturday Evening Post ran 30,000 between 1930 and 1960. Today, few magazines give cartoons prominent display.

''Gag'' cartoons - to be distinguished from their politicking sisters - came of age with our illustrated magazines, which began to house them in the '20s and found them useful guests. Cartoons drew readers. They sold magazines. They even helped sell ads: Strewn throughout the back section, they kept readers thumbing pages, through the advertising messages bunched in the back of the book.

Readers turned to cartoons as they turned to favorite columnists. Ted Key's Hazel - the Baxters' pushy, warmhearted maid - was a star of The Saturday Evening Post. No one doubted who was head of the Baxter household. ''You're not talking to your wife now, chum!'' said Hazel, wagging her finger vigorously at Mr. Baxter's chest. Readers loved Hazel's affectionately sarcastic approach to domestic life (similar to Erma Bombeck's today), and she ran in the Post for 26 years, even spawning a television series.

Cartoons economically gave magazines an essay in a box. Readers came to know an artist's world view, elaborated in succeeding panels. They might look forward to meeting once again Helen Hokinson's never-changing New York dowagers, for instance - those vague, overweight, benevolent ladies whom she lovingly mocked in their haunts at women's clubs, beauty parlors, and Schrafft's. ''I hope, dear , you won't come back from Vassar with a lot of ideas,'' says one plump, shawled mother as her daughter packs for college. ''I like what you've been saying about Lindbergh,'' says another sweetly, to the delivery man bringing the New York Post.

Hokinson appeared in The New Yorker, the magazine credited with revolutionizing the gag cartoon in America. Since its founding in 1925, it has been the American magazine for cartoonists, comparable to England's Punch - a showcase for our best, including Steig, Steinberg, Thurber, and Price.

Of course, Hokinson belonged in The New Yorker - by subject and by style. There is an interplay between magazine and cartoon. Today's cartoons, like our magazines, have grown more specialized: Forbes runs a business cartoon; Field and Stream, cartoons on fishing. But effective cartoons have usually played off the specific character of the magazines in which they appeared. The early Esquire's cartoons were suitably sexy; Saturday Review's suitably literate; The New Yorker's suitably sophisticated. (''Oh, but you must come!'' says a chicly casual New Yorker woman talking on the telephone. ''We're only having people who hate New Year's Eve parties!'')

Humor editors know that the right context can enhance a cartoon's humor, as the wrong context can destroy it. Hazel, a Middle America cartoon, would simply not be funny in The New Yorker, not even to the reader who loves it in the Post. The editor must perceive not only what is funny but what will work in and for his magazine.

Cartoons have served magazines well. But lately, they seem to have worn their welcome thin. The New Yorker - and a few others - still give them ample room. David Levine's caricatures still illuminate the pages of The New York Review of Books (and often provide some of its most incisive commentary). But since the folding of the grand magazines (Look, Collier's, the original Post), the cartoon market has shrunk. Today's mass magazines run few cartoons. Some magazines, such as the renovated Esquire, no longer run them at all.

And yet our popular magazines certainly haven't grown more serious in the past two decades. They have, however, grown more ''service'' oriented. Editorial matter is pointedly useful: recipes, articles on fashion and home decoration. Not coincidentally, perhaps, these features are accompanied by advertising for food, clothing, home furnishings.

The cartoon does not tell us how to do anything. It does not lead us to buy anything. Indeed, one wonders whether the poor cartoon, devoted merely to the artful exercise of wit, has not been squeezed off the page by a vision of the ''useful'' about as broad as a dollar bill.